An Analytical Model for Buffer Hit Rate Prediction
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陕西省人民政府关于表彰第十届自然科学优秀学术论文的通报文章属性•【制定机关】陕西省人民政府•【公布日期】2008.09.12•【字号】陕政发[2008]42号•【施行日期】2008.09.12•【效力等级】地方规范性文件•【时效性】现行有效•【主题分类】科学技术综合规定正文陕西省人民政府关于表彰第十届自然科学优秀学术论文的通报(陕政发〔2008〕42号)各设区市人民政府,省人民政府各工作部门、各直属机构:根据《陕西省自然科学优秀学术论文评选办法》,经省自然科学优秀学术论文评选委员会评审,省政府决定对全省第十届自然科学优秀学术论文予以表彰,其中方钦志、王铁军、李慧敏的《PC/ABS合金的大变性拉伸性能(Large Tensile Deformation Behavior of PC/ABS Alloy)》等23篇论文为一等奖,孙浩、Theo riessen 的《集合对策的拟边缘贡献解(Semi-marginalistic Values for Set Games)》等65篇论文为二等奖,舒世昌、刘三羊的《Sn中具Moebius平坦法丛的子流形》等141篇论文为三等奖。
希望受表彰的同志再接再厉,在各自工作领域作出更大的成绩。
希望全省科技工作者向受表彰的同志学习,紧紧围绕我国经济社会发展中的重大现实课题,勇于创新、锐意进取、深入研究,全面推动我省的科技创新和科技进步。
附件:陕西省第十届自然科学优秀学术论文获奖名单陕西省人民政府二○○八年九月十二日附件陕西省第十届自然科学优秀学术论文获奖名单一等奖23项论文题目Large Tensile Deformation Behavior of PC/ABS Alloy(PC/ABS合金的大变性拉伸性能)arameters and structural disorder analysis for Cr3+ion in YGG crystals(YGG晶体中Cr3+离子自旋变研究)optimization of an analytical method for the determination of Sudan dyes in hot chilli p d chromatography with on-line electrogenerated BrO--luminol chemiluminescence detection(高效液相luminol化学发光法检测辣椒中的苏丹红)Numerical Analysis of Isothermal Gaseous Flows in Microchannel(圆形微通道内气体等温流动)混合物整体电导率的研究fferences of the Early Cambrian Chengjiang and Recent lingulids and their implications(早寒舌形贝形态解剖差异及其进化意义)陕西省椒样薄荷适种区域及其生态因素影响研究土壤水分对杜仲剥皮再生的影响温度对兰州鲇消化酶活性的影响基于MFA方法的陕西省物质减量化分析ffect of insulin in the ischemic/reperfused canine heart Role of Akt-stimulated NO producti灌注犬冠状动脉的保护作用:Akt-NO的关键作用)The Repression of Human Differentiation Related Gene NDRG2 Expression by Myc via Miz-Interaction with the NDRG2 Core Promoter(Myc抑制分化相关基因NDRG2的表达依赖于Miz-1与NDRG2核心启rion protein promotes invasion and metastasis of gastric cancer(朊蛋白促进胃癌侵袭和转移的分子乳腺癌术后1-3个腋淋巴结阳性且未行辅助放疗患者腋窝引流液中定量分子检测的意义Two frameshift mutations of the double-stranded RNA-deaminase gene in Chinese pedigrees with dyschromatosis symmetrica hereditaria(中国DSH家系DS变)osaponins from the starfish Culcita novaeguineae and their bioactivity(面包海星中三个新的海星皂淮南煤田次生生物成因与热成因混合型煤层气成藏动力学系统演化ation on Spun-dyed Polyester Filaments during Processing(纺液着色涤纶长丝在加工过程中的颜色变化规高强冷弯薄壁型钢卷边槽形截面轴压柱畸变屈曲试验研究atorial Explosion Problem When Calculating the Multiple Hit Vulnerability of Aircraft(解决组中易损性计算方法)Prediction of protein homo-pseudo amino acid composition:Approached with an improved feature extraction and Naive Ba (基于伪氨基酸组成成分:加权自相关函数特征提取法和朴素贝叶斯特征融合预测蛋白质同源寡聚体)一种面向个性化协同学习的任务生成方法新型振动搅拌装置的试验研究陕西省第十届自然科学优秀学术论文获奖名单二等奖65项论文题目Semi-marginalistic Values for Set Games(集合对策的拟边缘贡献解)Integral Trees with Diameters 5 and 6(直径为5和6的整谱树)forms for microstructured polymer optical fibre fabrication(微结构聚合物光纤的浇铸预制棒制备技术反式十氢萘类液晶的合成Evolved in the Gas Phase from Pyrolysis of Six Chinese Coals(六种中国煤在热解过程中硫向气相青藏高原东北侧一次MCC的环境流场及动力分析层间氧化带砂岩型铀矿床微生物地球化学特征及与铀成矿的关系研究-以吐哈盆地十红滩铀矿床为例扬子板块北缘碧口地区阳坝花岗闪长岩体成因研究及其地质意义从瞬变电磁场到波场的优化算法resolution radon transform and wavefield separation(一种高分辨率Radon变换实现波场分离)of two Y chromosomemicrosatellites in Chinese cattle(两个Y染色体微卫星在中国黄牛中的多态性分布ocess of aloin production and accumulation in Aloe arborescens (Asphodelaceae)leaves(木立过程的超微结构研究)pecies of the Genus Bryodemella (Orthoptera:Oedipodidae)Based on a Cladistic Analysis(支序分析(直翅目:斑翅蝗科))天然林保护工程实施中存在问题及对策研究-以陕西省为例坡面汇流汇沙与侵蚀-搬运-沉积过程科学推进黄土高原水土保持生态建设估算流域非点源污染负荷的降雨量差值法地下水嘧磺隆污染分析研究高压注浆渗流数学模型与工程应用西龙池抽水蓄能电站大坡度超长斜井开挖施工技术县级地质灾害防治管理评价指标体系探讨纸坊沟流域生态经济系统演变规律研究--兼论“退耕还林(草)”下生态经济系统演变规律信息哲学的基本理论及其对哲学的全新突破让科技与人文在工程中融合中国文理综合性大学学报考网络资源能否作为参考文献?重视选题优化选题办出精品期刊缺氧后处理抑制缺氧/复氧心肌细胞凋亡:过氧亚硝基阴离子的作用receives GABAergic projection from reticular thalamic nuclues in rat(丘脑中央下核接受丘脑网状estin by all-trans retinoic acid through STAT1 in cancer cell differentiation process(在肿瘤通过STAT1上调restin基因的转录)组胺是心脏交感神经系统递质的证据乙型肝炎表面抗原阳性孕妇妊娠早期绒毛细胞乙型病毒感染状况的研究陕西省O157大肠杆菌分布研究al properties of single myocardial cells from Koch triangle of rabbit heart(家兔心脏Koch三和电生理特征)efractory anemia with a combination regimen of all-trans retinoic acid,calcitriol,and a 维生素D3 联合雄激素对原发性难治性贫血的有效治疗)髓鞘碱性蛋白反应性淋巴细胞对神经细胞的作用creatic cancer based on injection of pcDNA3.1/CCK plasmid with xenogeneic homologous cholecy粒的构建及其在仓鼠体内表达)embrane anchored staphylococcal enterotoxin A generate effective antitumor immunity(B7.1和跨膜苗的抗肿瘤免疫效应)with tumor cells or transfected with tumor total RNA as potential cancer vaccines against (DC融合瘤苗与DC-RNA瘤苗抗原发性肝癌免疫学效应的实验研究)驻相与阻抗-精神分析学心理治疗与禅宗参悟的异曲同工MN9202在Beagle犬肝微粒体酶中的代谢动力学盐酸塔斯品碱促进大鼠皮肤创伤愈合及其作用机制研究太白楤木对成纤维细胞增殖及形态学的影响绞股蓝人参皂甙的组织化学定位及其含量的变化利用CHAMP卫星几何法轨道恢复地球重力场模型双目序列影象3维运动物体定位跟踪d on microstructure and property of friction welded joint between copper and stainless ste头组织与性能的影响)Fe掺杂对纳米复合Ag-SnO2电接触合金电弧演化行为的影响论保水采煤问题Coating for Nano super Dirt-repellency of Cashmere Fabric(纳米超双疏羊绒织物整理)统一强度理论在湿陷性黄土-桩-上部结构共同作用分析中的应用双频合成振动压实试验研究既有桥梁技术状况评价及检算系数Z1的确定斜入射弹丸着靶位置立靶测量原理沉积角度对MgO介质保护膜性能的影响A Robust Adaptive Capon Beamforming(一种稳健的自适应波束形成技术)f Radar Imaging Using Frequency-Stepped Chirp Signals(线性调频步进信号体制雷达成像中的几个问题)集成电路互连线寿命的工艺缺陷影响分析及早期可靠性估计模型研究(系列论文)一种满足马尔可夫性质的不完全信息下的Web服务组合方法视觉测量中亚像元图像特征定位算法特高压直流输电换流阀运行试验合成回路研究城市局部电网的稳定控制研究循环流化床锅炉技术领域几个前沿课题的研究165MN自由锻造油压机的液压控制系统基于S7-200PLC切纸机电气系统设计三等奖141项论文题目S●中具Moebius平坦法丛的子流形for Transport Aircraft High-lift Configurations Using Cartesian Grid Methods(采用直角网格方法置数值模拟)que Applied to Unsteady Viscous Flow Simulation by a Fully Implicit Solver(用于非定常粘性流拟的变形网格技术)lysis of fuzzy stochastic truss structures under fuzzy stochastic excitation(模糊随机激励下模的动力响应分析)upper atmospheric wind and temperature based on the Voigt line shape profile(基于佛克脱光气风场和温度的探测原理)le-transformation of Electromagnetic Theory and Its Applications(电磁场理论的尺度变换及其应用)全尺寸目标激光脉冲后向散射回波功率的测定和建模有偏压光折变晶体中的小振幅行波孤子流动注射电化学发光分析法测定注射液中的硫酸庆大霉素球形α-Fe2O3纳米粉体的超声水解法合成与表征quanickel(II)]-μ-5-hydroxyisophthalato](一个新颖的5-羟基间苯二甲酸镍超分子配位聚合物的水热合成与结丁二酸改性二氧化硅胶体球的制备及其胶体晶体的组装of Separating Cr(Ⅵ)using a Mixed Carrier Emulsion Membrane(混合载体乳状液膜法分离Cr(Ⅵ)LB复合膜选择性检测水中痕量镉离子的方法研究陕西省作物气候生产力的地理分布与变化特征热惯量法在干旱遥感监测中的应用研究渭河陕西段河道地貌演变机制及其影响研究青藏高原多年冻土区两类低角度滑坡灾害形成机理探讨基于OFDM的高速遥传电缆调制解调器设计VXWORKS操作系统下COMPACTPCI总线的驱动与控制技术层状介质井中电测数值计算及其应用研究ptibility Anomalies Directly Indicating Oil and Gas Reservoirs(油气区地表黄土磁化率异常直接指示CSN1S2、CSN3和β-1g基因对西农萨能奶山羊产奶性能的影响光系统Ⅱ核心复合物的稳态荧光光谱河北大学博物馆馆藏食蚜蝇亚科分类研究马蹄香繁殖生物学研究(系列研究论文)A new genus and a new species of arcypteridae (orthoptera,acridoidea)from xinjiang uigur antonomous region of china(新疆网翅蝗科一新属一新种)陕西延安市区蝶类多样性初探氮磷钾肥料对魔芋产量的影响效应研究影响关中东部冬季日光温室生产的气候变化特点高酸苹果的组织培养快繁技术研究都市农业发展的SWOT分析农用地征用的综合价格评估农田害鼠夏峰期发生量模糊预测延安地区荞麦钩翅蛾的发生规律及防治措施榆林市农业机械化发展对策及措施浅谈我省森林公园总体规划编制中应该注意的几个问题GGR6在南方红豆杉扦插育苗中的作用研究基于UNDP项目的天保工程执行效果初步研究-以马头滩林业局为例淤地坝干容重的监理控制试验黄河中游粗泥沙集中来源区大型拦泥库工程建设资源分析模型黄土高原建设与研究的若干问题探讨界壳的泛系观控模型及其在水资源中的应用黄河壶口-三门峡段渔业水域重金属污染及模糊数学评价陕西渔业生态环境可持续发展探讨陕西水产品质量安全面临的问题与对策娘娘滩水库枢纽布置方案选择固化土集流面无侧限抗压强度影响因素研究渠道衬砌纤维固化土工程特性的试验研究失地农民贫困现状缘于中国农民权利贫困--换个角度谈征地补偿制度知识经济时代的高校科研管理改进的兼顾“功能性”与“均衡性”综合评价方法核在管理者绩效考中的应用尖端技术的军民共用趋势及其应对思路基于历史费用的鱼雷经济寿命预测墨家科学理性的形成及其中绝近代科学的精神气质及其文化背景和希腊来源后现代主义的数学观及其认识海德格尔的技术之思与李约瑟问题科技论文发表费收取的合理性及其规范网络环境下地方科技文献资源共享的实践-陕西省科技文献资源共享服务系统分析重组人B淋巴细胞刺激因子包涵体的表达与纯化gic modulation of antinociception induced by morphine microinjected into the ventrolateral o (GABA能调制参与介导腹外侧眶皮层内微量注射吗啡诱发的抗伤害效应)chromosomal STR haplotypes in Chinese Uigur ethnic group(维吾尔族Y-STR单倍型遗传多态性)xy9902对MC3T3-E1细胞的增殖和分化作用ameliorates hyperthyroidism of rats and mice attributed to its adsorptive effect(蒙脱石的抗甲陕西省鼠疫疫区媒介蚤季节消长研究西安市麻疹流行病原毒株和疫苗免疫因素研究西安市麻疹野病毒核蛋白基因序列分析西安市部分男男性接触者AIDS高危行为分析en against hypoxic-ischemic brain damage in neonatal and possible mechanisms(雄激素对新生大鼠的保护作用及机制研究)tion and bioinformatics analysis of immunogenic antigens in multiple myeloma(多发性骨髓瘤抗原筛选及生物信息学分析)hTERT基因核心启动子调控的TRAIL表达载体的构建及对卵巢癌细胞凋亡的影响二十二碳-6烯酸对注意缺陷多动障碍患儿神经生化及行为影响的研究人热休克蛋白90β-cDNA基因克隆及其真核表达载体的构建cific antibodies for early diagnosis and management of syphilis(特异性抗体对梅毒的早期诊断和管经颅多普勒在颅脑损伤后的变化及其临床意义肾脏细胞凋亡在梗阻性黄疸大鼠肾脏损害中的作用及丹参的影响HBsAg基因转染CD34+造血干细胞来源的树突状细胞诱导抗原特异性细胞毒性T淋巴细胞反应同源异型盒BP1基因在肺癌中的表达及意义TIL细胞治疗恶性胸(腹)腔积液的临床研究几丁糖与二甲亚砜对大鼠多柔比星外渗性损伤防护的实验研究96例晚期癌症病人需求评估研究APACHEⅡ评分在ICU护理中的应用与研究心脏移植病人围术期护理语词推理测验的词性、词类和词频对项目难度和反应时间的效应文拉法辛联合利培酮治疗精神分裂症阴性症状的疗效观察甲芬那酸分散片在健康人体内的药动学。
Determination of Pesticide Minimum Residue Limits in Essential OilsReport No 3A report for the Rural Industries Research andDevelopment CorporationBy Professor R. C. Menary & Ms S. M. GarlandJune 2004RIRDC Publication No 04/023RIRDC Project No UT-23A© 2004 Rural Industries Research and Development Corporation.All rights reserved.ISBN 0642 58733 7ISSN 1440-6845‘Determination of pesticide minimum residue limits in essential oils’, Report No 3Publication No 04/023Project no.UT-23AThe views expressed and the conclusions reached in this publication are those of the author and not necessarily those of persons consulted. RIRDC shall not be responsible in any way whatsoever to any person who relies in whole or in part on the contents of this report.This publication is copyright. However, RIRDC encourages wide dissemination of its research, providing the Corporation is clearly acknowledged. For any other enquiries concerning reproduction, contact the Publications Manager on phone 02 6272 3186.Researcher Contact DetailsProfessor R. C. Menary & Ms S. M. GarlandSchool of Agricultural ScienceUniversity of TasmaniaGPO Box 252-54HobartTasmania 7001AustraliaPhone: (03) 6226 2723Fax: (03) 6226 7609Email: r.menary@.auIn submitting this report, the researcher has agreed to RIRDC publishing this material in its edited form.RIRDC Contact DetailsRural Industries Research and Development CorporationLevel 1, AMA House42 Macquarie StreetBARTON ACT 2600PO Box 4776KINGSTON ACT 2604Phone: 02 6272 4819Fax: 02 6272 5877Email: rirdc@.auWebsite: .auPublished in June 2004Printed on environmentally friendly paper by Canprint.FOREWORDInternational regulatory authorities are standardising the levels of pesticide residues present in products on the world market which are considered acceptable. The analytical methods to be used to confirm residue levels are also being standardised. To constructively participate in these processes, Australia must have a research base capable of constructively contributing to the establishment of methodologies and must be in a position to assess the levels of contamination within our own products.Methods for the analysis for pesticide residues rarely deal with their detection in the matrix of essential oils. This project is designed to develop and validate analytical methods and apply that methodology to monitor pesticide levels in oils produced from commercial harvests. This will provide an overview of the levels of pesticide residues we can expect in our produce when normal pesticide management programs are adhered to.The proposal to produce a manual which deals with the specific problems associated with detection of pesticide residues in essential oils is intended to benefit the essential oil industry throughout Australia and may prove useful to other horticultural products.This report is the third in a series of four project reports presented to RIRDC on this subject. It is accompanied by a technical manual detailing methodologies appropriate to the analysis for pesticide residues in essential oils.This project was part funded from RIRDC Core Funds which are provided by the Australian Government. Funding was also provided by Essential Oils of Tasmania and Natural Plant Extracts Cooperative Society Ltd.This report, an addition to RIRDC’s diverse range of over 1000 research publications, forms part of our Essential Oils and Plant Extracts R&D program, which aims for an Australian essential oils and plant extracts industry that has established international leadership in production, value adding and marketing.Most of our publications are available for viewing, downloading or purchasing online through our website:•downloads at .au/fullreports/index.html•purchases at .au/eshopSimon HearnManaging DirectorRural Industries Research and Development CorporationAcknowledgementsOur gratitude and recognition is extended to Dr. Noel Davies (Central Science Laboratories, University of Tasmania) who provided considerable expertise in establishing procedures for chromatography mass spectrometry.The contribution to extraction methodologies and experimental work-up of Mr Garth Oliver, Research Assistant, cannot be underestimated and we gratefully acknowledge his enthusiasm and novel approaches.Financial and ‘in kind’ support was provided by Essential Oils Industry of Tasmania, (EOT).AbbreviationsADI Average Daily IntakeAGAL Australian Government Analytical Laboratoriesingredientai activeAPCI Atmospheric Pressure Chemical IonisationBAP Best Agricultural PracticesenergyCE collisionDETA DiethylenetriamineECD Electron Capture DetectorionisationESI ElectrosprayFPD Flame Photometric DetectionChromatographyGC GasResolutionHR HighChromatographyLC LiquidLC MSMS Liquid Chromatography with detection monitoring the fragments of Mass Selected ionsMRL Maximum Residue LimitSpectrometryMS MassNRA National Registration AuthorityR.S.D. Relative Standard DeviationSFE Supercritical Fluid ExtractionSIM Single Ion MonitoringSPE Solid Phase ExtractionTIC Total Ion ChromatogramContents FOREWORD (III)ACKNOWLEDGEMENTS (IV)ABBREVIATIONS (V)CONTENTS (VI)EXECUTIVE SUMMARY (VII)1. INTRODUCTION (1)1.1B ACKGROUND TO THE P ROJECT (1)1.2O BJECTIVES (2)1.3M ETHODOLOGY (2)2. EXPERIMENTAL PROTOCOLS & DETAILED RESULTS (3)2.1M ETHOD D EVELOPMENT (3)2.2M ONITORING OF H ARVESTS (42)2.3P RODUCTION OF M ANUAL (46)3. CONCLUSIONS (47)IMPLICATIONS & RECOMMENDATIONS (50)BIBLIOGRAPHY (50)Executive SummaryThe main objective of this project was to continue method development for the detection of pesticide residues in essential oils, to apply those methodologies to screen oils produced by major growers in the industry and to produce a manual to consolidate and coordinate the results of the research. Method development focussed on the effectiveness of clean-up techniques, validation of existing techniques, the assessment of the application of gas chromatography (GC) with detection using electron capture detectors (ECD), flame photometric detectors (FPD) and high pressure liquid chromatography (HPLC) with ion trap mass selective (MS) detection.The capacity of disposable C18 cartridges to separate components of boronia oil was found to be limited with the majority of boronia components being eluted on the solvent front, with little to no separation achieved. The cartridges were useful, however, in establishing the likely interaction of reverse phases (RP) C18 columns with components of essential oils, using polar mobile phases . The loading of large amounts of oil onto RP HPLC columns presents the risk of permanently contaminating the bonded phases. The lack of retention of components on disposable SPE C18 cartridges, despite the highly polar mobile phase, presented a good indication that essential oils would not accumulate on HPLC RP columns.The removal of non-polar essential oil components by solvent partitioning of distilled oils was minimal, with the recovery of pesticides equivalent to that recorded for the essential oil components. However application of this technique was of advantage in the analysis of solvent extracted essential oils such as those produced from boronia and blackcurrant.ECD was found to be successful in the detection of terbacil, bromacil, haloxyfop ester, propiconazole, tebuconazole and difenaconzole. However, analysis of pesticide residues in essential oils by application of GC ECD is not sufficiently sensitive to allow for a definitive identification of any contaminant. As a screen, ECD will only be effective in establishing that, in the absence of a peak eluting with the correct retention time, no gross contamination of pesticide residues in an essential oil has occurred . In the situation where a peak is recorded with the correct elution characteristics, and which is enhanced when the sample is fortified with the target analyte, a second means of contaminant identification would be required. ECD, then, can only be used to rule out significant contamination and could not in itself be adequate for a positive identification of pesticide contamination.Benchtop GC daughter, daughter mass spectrometry (MSMS) was assessed and was not considered practical for the detection of pesticide residues within the matrix of essential oils without comprehensive clean-up methodologies. The elution of all components into the mass spectrometer would quickly lead to detector contamination.Method validation for the detection of 6 common pesticides in boronia oil using GC high resolution mass spectrometry was completed. An analytical technique for the detection of monocrotophos in essential oils was developed using LC with detection by MSMS. The methodology included an aqueous extraction step which removed many essential oil components from the sample.Further method development of LC MSMS included the assessment of electrospray ionisation (ESI) and atmospheric pressure chemical ionisation (APCI. For the chemicals trialed, ESI has limited application. No response was recorded for some of the most commonly used pesticides in the essential oil industry, such as linuron, oxyflurofen, and bromacil. Overall, there was very little difference between the sensitivity for ESI and APCI. However, APCI was slightly more sensitive for the commonly used pesticides, tebuconazole and propiconazole, and showed a response, though poor, to linuron and oxyflurofen. In addition, APCI was the preferred ionisation method for the following reasons,♦APCI uses less nitrogen gas compared to ESI, making overnight runs less costly;♦APCI does not have the high back pressure associated with ionisation by ESI such that APCI can be run in conjunction with UV-VIS without risk of fracturing the cell, which is pressure sensitive. Analytes that ionised in the negative APCI mode were incorporated into a separate screen which included bromacil, terbacil, and the esters of the fluazifop and haloxyfop acids. Further work using APCI in the positive mode formed the basis for the inclusion of monocrotophos, pirimicarb, propazine and difenaconazole into the standard screen already established. Acephate, carbaryl, dimethoate, ethofumesate and pendimethalin all required further work for enhanced ionisation and / or improved elution profiles. Negative ionisation mode for APCI gave improved characteristics for dicamba, procymidone, MCPA and mecoprop.The thirteen pesticides included in this general screen were monocrotophos, simazine, cyanazine, pirimicarb, propazine, sethoxydim, prometryb, tebuconazole, propiconazole, , difenoconazole and the esters of fluroxypyr, fluazifop and haloxyfop.. Bromacil and terbacil were not included as both require negative ionisation and elute within the same time window as simazine, which requires positive ionisation. Cycling the MS between the two modes was not practical.The method validation was tested against three oils, peppermint, parsley and fennel.Detection limits ranged from 0.1 to 0.5 mgkg-1 within the matrix of the essential oils, with a linear relationship established between pesticide concentration and peak height (r2 greater than 0.997) and repeatabilities, as described by the relative standard deviation (r.s.d), ranging from 3 to 19%. The type of oil analysed had minimal effect on the response function as expressed by slope of the standard curve.The pesticides which have an carboxylic acid moiety such as fluazifop, haloxyfop and fluroxypyr, present several complications in any analytical method development. The commercial preparations usually have the carboxylic acid in the ester form, which is hydrolysed to the active acidic form on contact with soil and vegetation. In addition, the esters may be present in several forms, such as the ethoxy ethyl or butyl esters. Detection using ESI was tested. Preliminary results indicate that ESI is unsuitable for haloxyfop and fluroxypyr ester. Fluazifop possessed good ionisation characteristics using ESI, with responses approximately thirty times that recorded for haxloyfop. Poor chromatography and response necessitated improved mobile phase and the effect of pH on elution characteristics was considered the most critical parameter. The inclusion of acetic acid improved peak resolution.The LC MSMS method for the detection of dicamba, fluroxypyr, MCPA, mecoprop and haloxyfop in peppermint and fennel distilled oils underwent the validation process. Detection limits ranged from 0.01 to 0.1 mgkg-1Extraction protocols and LC MSMS methods for the detection of paraquat and diquat were developed. ESI produced excellent responses for both paraquat and diquat, after some modifications of the mobile phase. Extraction methodology using aqueous phases were developed. Extraction with carbonate buffer proved to be the most effective in terms of recovery and robustness. A total ion chromatogram of the LC run of an aqueous extract of essential oil was recorded and detection using a photodiode array detector confirmed that very little essential oil matrix was co-extracted. The low background noise indicated that samples could be introduced directly into the MS. This presented a most efficient and rapid way for analysis of paraquat and diquat, avoiding the need for specialised columns or modifiers to be included in the mobile phase to instigate ion exchange.The adsorbtion of paraquat and diquat onto glass and other surfaces was reduced by the inclusion of diethylenetriamine (DETA). DETA preferentially accumulates on the surfaces of sample containers, competitively binding to the adsorption sites. All glassware used in the paraquat diquat analysis were washed in a 5% solution of 0.1M DETA, DETA was included in all standard curve preparations, oils were extracted with aqueous DETA and the mobile phase was changed to 50:50 DETA / methanol. The stainless steel tubing on the switching valve was replaced with teflon, further improvingreproducibility. Method validation was undertaken of the analysis of paraquat and diquat using the protocols established. The relationship between analyte concentration and peak area was not linear at low concentrations, with adsorption more pronounced for paraquat, such that the response for this analyte was half that seen for diquat and the 0.1 mgkg-1 level.The development of a method for the detection of the dithiocarbamate, mancozeb was commenced. Disodium N, N'-ethylenebis(dithiocarbamate) was synthesised as a standard for the derivatised final analytical product. An LC method, with detection using MSMS, was successfully completed. The inclusion of a phase transfer reagent, tetrabutylammonium hyrdrogen sulfate, required in the derivatisation step, contaminated the LC MSMS system, such that any signal from the target analyte was masked. Alternatives to the phase transfer reagent are now being investigated.Monitoring of harvests were undertaken for the years spanning 1998 to 2001. Screens were conducted covering a range of solvent extracted and distilled oils. Residues tested for included tebuconazole, simazine, terbacil, bromacil, sethoxydim, prometryn, oxyflurofen, pirimicarb, difenaconazole, the herbicides with acidic moieties and paraquat and diquat. Problems continued for residues of propiconazole in boronia in the 1998 / 1999 year with levels to 1 mgkg-1 still being detected. Prometryn residues were detected in a large number of samples of parsley oil.Finally the information gleaned over years of research was collated into a manual designed to allow intending analysts to determine methodologies and equipment most suited to the type of the pesticide of interest and the applicability of analytical equipment generally available.1. Introduction1.1 Background to the ProjectResearch undertaken by the Horticultural Research Group at the University of Tasmania, into pesticide residues in essential oils has been ongoing for several years and has dealt with the problems specific to the analysis of residues within the matrix of essential oils. Analytical methods for pesticides have been developed exploiting the high degree of specificity and selectivity afforded by high resolution gas chromatography mass spectrometry. Standard curves, reproducibility and detection limits were established for each. Chemicals, otherwise not amenable to gas chromatography, were derivatised and incorporated into a separate screen to cover pesticides with acidic moieties.Research has been conducted into low resolution GC mass selective detectors (MSD and GC ECD. Low resolution GC MSD achieved detection to levels of 1 mgkg-1 in boronia oil, whilst analysis using GC ECD require a clean-up step to effectively detect halogenated chemicals below 1mgkg-1.Dithane (mancozeb) residues were digested using acidified stannous chloride and the carbon disulphide generated from this reaction analysed by GC coupled to FPD in the sulphur mode.Field trials in peppermint crops were established in accordance with the guidelines published by the National Registration Authority (NRA), monitoring the dissipation of Tilt and Folicur residues in peppermint leaves and the co-distillation of these residues with hydro-distilled peppermint oils were assessed.Development of extraction protocols, analytical methods, harvest monitoring and field trials were continued and were detailed in a subsequent report. Solvent-based extractions and supercritical fluid extraction (SFE) was found to have limited application in the clean-up of essential oilsIn conjunction with Essential Oils of Tasmania (EOT), the contamination risk, associated with the introduction of a range of herbicides, was assessed through a series of field trials. This required analytical method development to detect residues in boronia flowers, leaf and oil. The methodology for a further nine pesticides was successful applied. Detection limits for these chemicals ranged from 0.002 mgkg-1 to 0.1 mgkg-1. In addition, methods were developed to analyse for herbicides with active ingredients (ai) whose structure contained acidic functional groups. Two methods of pesticide application were trialed. Directed sprays refer to those directed on the stems and leaves of weeds at the base of boronia trees throughout the trial plot. Cover sprays were applied over the entire canopy. For all herbicides for which significant residues were detected, it was evident that cover sprays resulted in contamination levels ten times those occurring as a result of directed spraying in some instances. Chloropropham, terbacil and simazine presented potentially serious residue problems, with translocation of the chemical from vegetative material to the flower clearly evident.Directed spray applications of diuron and dimethenamid presented only low residue levels in extracted flowers with adequate control of weeds. Oxyflurofen and the mixture of bromacil and diuron (Krovar) presented only low levels of residues when used as a directed spray and were effective as both post and pre-emergent herbicides. Only very low levels of residues of both sethoxydim and norflurazon were detected in boronia oil produced in crops treated with directed spray applications. Sethoxydim was effective as a cover spray for grasses whilst norflurazon showed potential as herbicide to be used in combination with other chemicals such as diuron, paraquat and diquat. Little contamination of boronia oils by herbicides with acidic moieties was found. This advantage, however, appears to be offset by the relatively poor weed control. Both pendimethalin and haloxyfop showed good weed control. Both, however, present problems with chemical residues in boronia oil and should only be used as a directed sprayThe stability of tebuconazole, monocrotophos and propiconazole in boronia under standard storage conditions was investigated. Field trials of tebuconazole and propiconazole were established in commercial boronia crops and the dissipation of both were monitored over time. The amount of pesticide detected in the oils was related to that originally present in the flowers from which the oils were produced.Experiments were conducted to determine whether the accumulation of terbacil residues in peppermint was retarding plant vigour. The level recorded in the peppermint leaves were comparatively low. Itis unlikely that terbacil carry over is the cause for the lack of vigour in young peppermint plants.Boronia oils produced in 1996, 1997 and 1998 were screened for pesticides using the analytical methods developed. High levels of residues of propiconazole were shown to persist in crops harvested up until 1998. Field trials have shown that propiconazole residues should not present problems if the fungicide is used as recommended by the manufacturers.1.2 Objectives♦Provide the industry, including the Standards Association of Australia Committee CH21, with a concise practical reference, immediately relevant to the Australian essential oil industry♦Facilitate the transfer of technology from a research base to practical application in routine monitoring programs♦Continue the development of analytical methods for the detection of metabolites of the active ingredients of pesticide in essential oils.♦Validate the methods developed.♦Provide industry with data supporting assurances of quality for all exported products.♦Provide a benchmark from which Australia may negotiate the setting of a realistic maximum residue limit (MRL)♦Determine whether the rate of uptake is relative to the concentration of active ingredient on the leaf surface may establish the minimum application rates for effective pest control.1.3 MethodologyThree approaches were used to achieve the objectives set out above.♦Continue the development and validation of analytical methods for the detection of pesticide residues in essential oils. Analytical methods were developed using gas chromatography high resolution mass spectrometry (GC HR MS), GC ECD, GC FPD and high pressure liquid chromatography with detection using MSMS.♦Provide industry with data supporting assurances of quality for all exported products.♦Coordinate research results into a comprehensive manual outlining practical approaches to the development of analytical proceduresOne aspect of the commissioning of this project was to provide a cost effective analytical resource to assess the degree of the pesticide contamination already occurring in the essential oils industry using standard pesticide regimens. Oil samples from annual harvests were analysed for the presence of pesticide residues. Data from preceding years were collated to determine the progress or otherwise, in the application of best agricultural practice (BAP).2. Experimental Protocols & Detailed ResultsThe experimental conditions and results are presented under the following headings:♦Method Development♦Monitoring of Commercial Harvests♦Production of a Manual2.1 Method DevelopmentMethod development focussed on the effectiveness of clean-up techniques, validation of existing techniques, the assessment of the application of GC ECD and FPD and high pressure liquid chromatography with ion trap MS, MS detection.2.1.1 Clean-up Methodologies2.1.1.i. Application of Disposable SPE cartridges in the clean-up of pesticide residues in essentialoilsLiterature reviews provided limited information with regards to the separation of contaminants within essential oils. The retention characteristics of disposable C18 cartridges were trialed.Experiment 1;Aim : To assess the capacity of disposable C18 cartridges to the separation of boronia oil components. Experimental : Boronia concrete (49.8 mg) was dissolved in 0.5 mL of acetone and 0.4 mL of chloroform was added. 1mg of octadecane was added as an internal standard. A C18 Sep-Pak Classic cartridge (short body) was pre- conditioned with 1.25 mL of methanol, which was passed through the column at 7.5 mLmin-1, followed by 1.25 mL of acetone, at the same flow rate. The boronia samplewas then applied to the column at 2 mLmin-1 flow and eluted with 1.25 mL of acetone / chloroform (5/ 4) and then eluted with a further 2.5 mL of chloroform. 5 fractions of 25 drops each were collected. The fractions were analysed by GC FID using the following parametersAnalytical parameters6890PackardHewlettGCcolumn: Hewlett Packard 5MS 30m, i.d 0.32µmcarrier gas instrument grade nitrogeninjection volume: 1µL (split)injector temp: 250°Cdetector temp: 280°Cinital temp: 50°C (3 min), 10°Cmin-1 to 270°C (7 mins)head pressure : 10psi.Results : Table 1 record the percentage volatiles detected in the fractions collectedFraction 1 2 3 4 5 % components eluting 18 67 13 2636%monoterpenes 15%sesquiquiterpenes 33 65 2%high M.W components 1 43 47 9Table 1. Percentage volatiles eluting from SPE C18 cartridgesDiscussion : The majority of boronia components eluted on the solvent front, effecting minimal separation. This area of SPE clean-up of essential oils requires a wide ranging investigation, varying parameters such as cartridge type and polarity of mobile phase.Experiment 2.Aim : For the development of methods using LC MSMS without clean-up steps, the potential for oil components to accumulate on the reverse phase (RP) column must be assessed. The retention of essential oil components on SPE C18 cartridges, using the same mobile phase as that to be used in theLC system, would provide a good indication as to the risk of contamination of the LC columns withoil components.Experimental: Parsley oil (20-30 mg) was weighed into a GC vial. 200 µL of a 10 µgmL-1 solution (equivalent to 100mgkg-1 in oil) of each of sethoxydim, simazine, terbacil, prometryn, tebuconazoleand propiconazole were used to spike the oil, which was then dissolved in 1.0 mL of acetonitrile. The solution was then slowly introduced to the C18 cartridge (Waters Sep Pac 'classic' C18 #51910) using a disposable luer lock, 10 mL syringe, under constant manual pressure, and eluted with 9 mLs of acetonitrile. Ten, 1 mL fractions were collected and transferred to GC vials. 1mg of octadecane was added to each vial and the samples were analysed by GC FID under the conditions described in experiment 1.The experiment was repeated using C18 cartridges which had been pre-conditioned with distilled waterfor 15 mins. Again, parsley oil, spiked with pesticides was eluted with acetonitrile and 5 x 1 mL fractions collected.Results: The majority of oil components and pesticides were eluted from the C18 cartridge in the firsttwo fractions. Little to no separation of the target pesticides from the oil matrix was achieved. Table2 lists the distribution of essential oil components in the fractions collected.Fraction 1 2 3 4 5 % components eluting 18 67 13 2663%monoterpenes 15%sesquiquiterpenes 33 65 2%high M.W components 1 43 47 9water conditioned% components eluting 35 56 8 12%monoterpenes 3068%sesquiquiterpenes 60 39 1 0%high M.W components 0 50 42 7Table 2. Percentage volatiles eluting for SPE C18 cartridgesFigure 1 shows a histogram of the percentage distribution of components from the oil in each of the four fractions.Figure 1. Histogram of the percentage of volatiles of distilled oils in each of four fraction elutedon SPE C18 cartridges (non-preconditioned)Figure 2. Histogram of the percentage of volatiles of distilled oils in each of four fraction elutedon SPE C18 cartridges (preconditioned)Discussion : The chemical properties of many of the target pesticides, including polarity, solubility in organic solvents and chromatographic behaviour, are similar to the majority of essential oil components. This precludes the effective separation of analytes from such matrices through the use of standard techniques, where the major focus is pre-concentration of pesticide residues from water or water based vegetative material. However, this experiment served to provide a good indication that under HPLC conditions, where a reverse phase C18 column is used in conjunction with acetonitrile / water based mobile phases, essential oil components do not remain on the column.。
28卷 第2期2011年2月微电子学与计算机MICROELECTRONICS &COMPUTERVol.28 No.2February 2011收稿日期:2010-04-12;修回日期:2010-06-03基金项目:自然科学基金资助项目(60473032)基于性能相似度的Buffer库压缩算法苏晓东,王静秋,马 鸿(中国科学院自动化研究所国家专用集成电路设计技术工程研究中心,北京100190)摘 要:以原库与压缩库的性能相似度为出发点,提出了一种buffer库压缩算法,并建立了虚单元、实单元和概率加权距离的概念.用环境参数对原库进行筛选,其结果构成虚单元库;对虚单元进行聚类,将中心点映射到实单元得到压缩库.将单元对环境的适应性量化,作为先验知识,为聚类中心的选择提供优先级.采用3种方案实现该算法思想,经实验证明,所得压缩库与原库的性能相似度高,误差平方和(SSE)仅为已有算法的9.6%、10.4%和6%.关键词:buffer库压缩;性能相似度;虚单元;聚类;加权距离中图分类号:TP391.72 文献标识码:A 文章编号:1000-7180(2011)02-0037-06Buffer Library Compression Based on Performance SimilaritySU Xiao-dong,WANG Jing-qiu,MA Hong(National ASIC Design Engineering Center,Institute of Automation,Chinese Academy of Science,Beijing 100190,China)Abstract:Taking performance similarity as a point of departure,this paper proposes an algorithm for buffer librarycompression.Concepts of virtual cell,real cell and probability weighted distance are established.Buffers with bestperformance under certain environment points are identified as cells of virtual library.Virtual cells are clustered inthe second step.Center of each cluster is finally mapped to compressed library.Environmental adaptability of eachbuffer is quantized to give priority to cluster center identification.Above idea is achieved by using three programs.Result shows that three implementations achieve 9.6%,10.4%and 6%of SSE respectively compared with existedalgorithm,which represents better performance similarities between compressed library and the unpruned one.Key words:buffer library compression;performance similarity;virtual cell;cluster;weighted distance1 引言随着IC芯片集成度的提高,全局互连线的电容值和延时不断增加,互连线的优化变得日益重要.导线的延时与线长的平方成正比,若将长导线分割成若干段较短的导线,则能够有效地降低导线的总延时.在各种技术中,插入buffer常被认为是减少长导线传播延时最有效的方法[1-2].它将互连线缩短使传播延时以平方关系减小,这在导线足够长时足以弥补插入buffer带来的额外延时[3].因此,许多EDA工具都将buffer插入作为重要功能之一.文献[4]提出了buffer插入的动态规划算法,以降低树形RC网络的Elmore延时,文献[5]提出导线的分段算法,能够在一根导线上插入多个buff-er.文献[6]将可选buffer的种类扩展到buffer库,文献[7]用聚类的方法对Buffer库进行压缩.研究该算法,我们发现压缩结果严重向大单元倾斜,在对长导线进行解耦时(此时,小尺寸buffer更常用),相对于原库,压缩库具有较大的性能损失.分析发现,原算法还存在一些其他问题。
离子液体作为添加剂的反向微乳毛细管电动色谱分析化妆品中的糖皮质激素陈新;田志壮;刘瑛;黄尧;曹玉华【摘要】A reversed microemulsion electrokinetic chromatographic (MEEKC) method was developed for the separation of three corticosteroids, including hydrocortisone, prednisone and hydrocortisone acetate by using 1-butyl-3-methylimizolium tetrafluoborate (BMIM - BF4 ) ionic liquid (IL) as addi tive. The effects of experimental conditions such as BMIM - BF4 concentration and pH value on sepa ration efficiency were investigated. The optimized conditions were as follows: 2. 4% sodium dodecylsulfate(SDS), 6. 6% 1-butanol, 0. 5% n-octane, 35 mmol/L BMIM - BF4, pH 2. 2 20 mmol/L NaH2PO4, an applied voltage of -20 kV and a detection wavelength of 250 nm. Under the optimized conditions, the calibration curves were linear in the range of 5 - 400, 5 - 400, 5 - 800 mg ·L - 1 for hydrocortisone, prednisone and hydrocortisone acetate with detection limits ( S/N= 3 ) of 0. 9, 0. 9, 1.2 mg/L, respectively. The RSDs(n =3) were less than 4. 3%. The average spiked recoveries were 102% , 97% and 94% , respectively. The results showed that the resolution of the IL - MEEKC method for the separation of hydrocortisone, prednisone and hydrocortisone acetate was higher than that of the conventional MEEKC method. The proposed method was simple, rapid and effective, and could be used for the quality control of cosmetics.%建立了以离子液体为添加剂的反向微乳毛细管电泳(IL-MEEKC)法分离测定化妆品中氢化可的松、泼尼松和醋酸氢化可的松3种糖皮质激素的方法.微乳毛细管电泳的最佳缓冲体系组成为:2.4% SDS+6.6%正丁醇+0.5%正辛烷+35 mmol/L BMIM-BF4+20 mmol/L磷酸二氢钠缓冲液(pH 2.2);运行电压-20 kV,检测波长250 nm.在优化实验条件下,氢化可的松、泼尼松和醋酸氢化可的松分别在5 ~400、5 ~400、5 ~800 mg·L-1范围内线性良好,检出限(S/N=3)分别为0.9、0.9、1.2 mg/L,相对标准偏差不大于4.3%,平均加标回收率分别为102%、97%和94%.结果表明,利用离子液体作为添加剂的反向微乳毛细管电泳方法分离3种糖皮质激素比常规的MEEKC具有更高的分离度.该方法快速、灵敏、有效,已成功用于实际样品中糖皮质激素的检测.【期刊名称】《分析测试学报》【年(卷),期】2011(030)002【总页数】5页(P203-206,212)【关键词】微乳毛细管电泳;糖皮质激素;离子液体;化妆品【作者】陈新;田志壮;刘瑛;黄尧;曹玉华【作者单位】江南大学,化学与材料工程学院,江苏,无锡,214122;郑州轻工业学院,材料与化学工程学院,河南,郑州,450002;江南大学,化学与材料工程学院,江苏,无锡,214122;江南大学,化学与材料工程学院,江苏,无锡,214122;江南大学,化学与材料工程学院,江苏,无锡,214122【正文语种】中文【中图分类】O657.7;Q57Abstract:A reversed microemulsion electrokineticchromatographic(MEEKC)method was developed for the separation ofthree corticosteroids,including hydrocortisone,prednisone and hydrocortisone acetate by using 1-butyl-3-methyli mizolium tetrafluoborate(BM I M-BF4)ionic liquid(I L)as additive.The effects of experimental conditions such asBM I M-BF4concentration and pH value on separation efficiency were investigated. The opti mized conditionswere as follows:2.4%sodium dodecyl sulfate(SDS),6.6%1-butanol,0.5%n-octane,35 mmol/L BM I M-BF4,pH 2.2 20 mmol/L NaH2PO4,an applied voltage of-20 kV and a detection wavelength of 250 nm.Under the optimized conditions,the calibration curves were linear in the range of 5-400,5-400,5-800 mg·L-1for hydrocortisone,prednisone and hydrocortisone acetate with detection limits(S/N=3)of 0.9,0.9,1.2 mg/L,respectively.The RSDs(n=3)were less than 4.3%. The average spiked recoverieswere 102%,97%and94%,respectively. The results showed that the resolution of theIL-MEEKC method for the separation of hydrocortisone,prednisone and hydrocortisone acetate was higher than that of the conventionalMEEKC method. The proposed method was simple,rapid and effective,and could be used for the quality control of cosmetics.Key words:microemulsion electrokineticchromatography;corticosteroids;ionic liquid;cos metics糖皮质激素(Corticosteroids)是由肾上腺皮质分泌的一类甾体激素,具有调节糖、脂肪和蛋白质的生物合成和代谢的作用,有重要的生理活性,如抗炎及抗过敏,降低毛细血管壁和细胞膜的通透性,减少炎性渗出等。
以一个给力的队友写一篇英语作文全文共3篇示例,供读者参考篇1An Awesome TeammateThey say that when you're part of a team, having the right people around you can make all the difference. I couldn't agree more after the incredible experience I've had this year with my teammate Emma. She has been an amazing partner to work with on our group projects, and I'm so grateful to have had her by my side through all the ups and downs.From the very start, Emma impressed me with her incredible work ethic and dedication. While the rest of us were still trying to figure out what the assignment was about, she had already mapped out a thorough plan and timeline to ensure we'd get everything done on time. Emma is one of those naturally organized people who always seems to be on top of everything without even trying. Her folders were impeccably labeled, her notes were crystal clear, and she never missed a deadline. It's like she was born with a superhuman ability to stay on task!But Emma's talents go far beyond just being an administrative whiz. What makes her such a sensational teammate is her passion for learning and her curiosity about the world around her. Emma has this contagious enthusiasm that brings out the best in everyone she works with. Whenever we'd hit a roadblock or get stuck on a tricky concept, she had an inexhaustible drive to dig deeper until we found the understanding we needed. Emma would pore over resources and spend hours researching until she mastered the material inside and out. Then she would turn around and explain it to the rest of us in a way that finally made it all click.I've worked with plenty of people who just wanted to skate by with the minimum effort required, but Emma is the total opposite. She took pride in her work and genuinely cared about producing something we could all be proud of. Emma pushed us all to go beyond simply regurgitating information and really think critically about the topics we were exploring. Discussions with her were never dull because she always found a way to look at things from a new angle and poke holes in our assumptions. Emma constantly challenged us to reevaluate our perspectives and back up our ideas. Working with her sharpened my analytical abilities in a way I couldn't have imagined.What I admire most about Emma, though, is her kindness and emotional intelligence. Group projects can get really stressful at times, but Emma always knew how to ease the tension with a well-timed joke or words of encouragement. Whenever I felt overwhelmed or started doubting myself, Emma was right there to boost my confidence and remind me how capable I was. She made me feel valued and like my contributions really mattered to the team's success. Emma created an environment where it was okay to take risks, make mistakes, and ask as many questions as we needed.At the same time, Emma didn't coddle us or shy away from constructive criticism. If someone's work wasn't quite up to par, she found a compassionate yet direct way to provide feedback so we could course correct. Emma was firm but fair, and she held everyone to high standards while giving us the support to meet those standards. She struck the perfect balance of being a patient mentor and a demanding coach. Emma's leadership skills were so impressive that I couldn't help but pick up on them and become a better teammate myself.Looking back on the year, I'm amazed by how much I've grown and how many new skills I've developed thanks to Emma's guidance. I've become a stronger writer, a more meticulousresearcher, and a more creative thinker. Group work always used to fill me with dread because of all the potential for conflicts and unequal efforts, but Emma showed me that when you have the right partner, it can be a hugely enriching experience. I feel incredibly fortunate that I got to be teammates with someone as brilliant, hard-working, and all-around wonderful as Emma.Of course, it hasn't been all sunshine and rainbows. We've had our fair share of late nights, moments of sheer panic, and inevitable disagreements along the way. That's all just part of the process when you're tackling big, ambitious projects together. The difference is that with Emma, even the tough times were made more bearable. She was a constant source of laughter during times of stress and frustration. Her positivity and determination were contagious in the face of every obstacle. When the going got tough, Emma was right there by my side, keeping me motivated and centered. We propped each other up and brought out the best in one another. That's what real teammates do.No matter what challenges came our way, I never once doubted that we'd be able to pull through because I had complete faith in Emma's abilities and our combined efforts. She made me approach every assignment with enthusiasm instead ofdread. I never felt judged or worried about looking stupid in front of Emma because I knew she had my back and only ever wanted to see me succeed. Having a teammate like that is more valuable than I can describe.So while I've learned tons of concrete skills this year that will serve me well academically and professionally, the biggest lesson Emma has taught me is the power of partnership and collaboration. Before this experience, I always saw myself as more of a solitary worker. Group projects filled me with anxiety about having to rely on others or deal with unequal workloads and clashing personalities. Emma shattered those preconceived notions and showed me that when you find the right match, teamwork can be an indescribably rewarding and productive experience.I feel so lucky that I got to be partners with someone as exceptional as Emma. She's helped me grow immensely as a student, but more importantly, as a person篇2A Teammate Like No OtherIt was the first day of basketball tryouts for the school team my freshman year of high school. I was pretty nervous, havingnever played organized basketball before. As I walked into the gym, the unmistakable sound of squeaking sneakers and bouncing balls filled the air. Kids were already shooting around, dribbling behind their backs and between their legs like it was nothing. I suddenly felt very small and very uncertain of my abilities.That's when I first noticed him – Jake. He was absolutely dominating one of the side baskets, effortlessly drainingthree-pointers from all around the arc. His form was flawless, his confidence striking. A senior on the varsity team, he looked like he was born to play basketball.I found an open ball and started my own shooting routine, trying my best to block out the talent surrounding me. After bricking my first few shots, I started to find a rhythm. That's when Jake first approached me."Nice stroke, freshman. Keep working and you'll be knocking those down in no time," he said with an encouraging smile before rejoining the varsity players.In that moment, a senior star player could have easily ignored me. He could have looked down on the scrawny new kid who couldn't make a shot to save his life. But instead, he offereda compliment and some words of advice. That was my first taste of who Jake was as a teammate.The next few days of tryouts were grueling, filled with endless drills, scrimmages, and wind sprints. Coach worked us to the bone, clearly trying to separate the players who just thought they could play from those who really wanted it.Through it all, Jake was our beacon of positivity. No matter how exhausted we were, he was always there with a loud "Let's go guys!" or "Keep pushing!" He demanded our best but in a way that was motivating, not demoralizing. The younger guys like me admired his work ethic and looked up to him as a role model of how to approach the game.When the roster was finally posted, my name was mercifully included. I had made the team, exceeding even my own expectations for my freshman year. As I studied the list, I noticed that Jake had been named a team captain. No surprise there – he was the unquestioned leader on and off the court.At our first few team practices, the cohesion and chemistry were still coming together. Playing time篇3An Awesome TeammateYou know that feeling when you're part of a team and everyone is working hard and contributing their best? It's an amazing feeling of camaraderie, shared purpose, and synergy. And then there's that one teammate who just takes it to another level – the teammate who is always going above and beyond, inspiring everyone around them to dig deeper and give more. That's the kind of teammate I want to write about.Mike was definitely that guy on our basketball team. From the moment he stepped onto the court for our first practice, you could just tell he was different. His intensity and work ethic were off the charts. He was the first one to arrive and the last one to leave every single day, putting in extra time to work on his skills before and after practice.But Mike wasn't just a gym rat – he had incredible natural talent too. The way he could handle the ball, shoot from anywhere on the court, and seem to defy gravity with his verticality was mind-blowing. Game after game, he would pull off these crazy plays that would have the crowd going wild. I'll never forget this one time he drove baseline, did a 360 turn in the air, and somehow managed to bank in a reverse layup while getting fouled. Insane!As amazing as Mike's skills were though, what really set him apart was his leadership and unselfishness. Some superstars let their egos get in the way and start putting themselves before the team. Not Mike. He was always the hardest worker, the biggest cheerleader for his teammates, and the first to give credit to others when we succeeded. He demanded everyone's best but also made sure to lift others up through his words and actions.I remember one game early in the season when I was really struggling and couldn't buy a basket. Mike could see I was getting down on myself, so he came over during a timeout and put his arm around me. He told me something I'll never forget: "Don't worry about the last play – it's gone. Just focus on making the next one count. I believe in you." Coming from Mike, those words meant everything. He had this ability to inspire you to dig deeper than you ever thought possible.Mike's positivity and team-first mindset were incredibly contagious. Whenever we were in a tough game and it felt like the momentum was slipping away, Mike would rally us together with an amazing speech about belief, perseverance, and leaving it all on the court for each other. We fed off his energy and often found ways to claw our way back into games as a result.Of course, being amazing on the court was only part of what made Mike such an awesome teammate. He was incredibly supportive and caring off the court too. I'll always remember when my grandfather passed away halfway through the season. I was absolutely devastated and seriously considered taking some time away from the team. But Mike showed up at my house with the rest of the guys, gave me the biggest hug, and let me know they had my back no matter what. Having that kind of support system during such a difficult time was invaluable.Mike didn't just look out for me – he treated the entire team like a family. He organized team dinners, movie nights, voluntary study halls (because he was just as dedicated in the classroom), you name it. Anytime anyone needed anything at all, Mike was the first one there to lend a hand or an ear to listen. He had this incredible way of bringing us all together and fostering an amazing sense of brotherhood.I could go on and on about what a stud Mike was, but I think you get the picture. He was the ultimate teammate –extraordinarily talented yet humble, selfless, hardworking, inspiring, and caring. Mike raised the level of everyone around him and created an environment where we all locked arms and gave everything we had for each other.Thanks to his leadership, our team achieved amazing things that season that no one could have predicted. And while we'll always remember the wins and crazy highlights, what I'll cherish most are the life lessons I learned from Mike about what it takes to be an awesome teammate. Wherever life takes me, I know the values and mindset he embodied will stick with me.I feel incredibly fortunate to have had Mike as a teammate and friend. He showed me what greatness truly looks like both on and off the court/field/etc. If I can be even half the teammate that Mike was, I'll consider myself successful. Guys like him don't come around very often – once-in-a-lifetime type of leaders who make everyone around them better through their actions and character. I'll be forever grateful for the impact he had on me.。
广东药科大学学报Journal of Guangdong Pharmaceutical University Mar.2024,40(2)分子印迹聚合物对血液中野百合碱-血红蛋白加合物的分析葛燕辉1,2,郑远茹1,郭景灿1,江芷惠1[1.广东药科大学药学院,广东广州510006;2.广东药科大学附属第一医院(临床医学院),广东广州510080]摘要:目的基于分子印迹技术,建立快速检测体内野百合碱和血红蛋白加合物的方法。
方法以制备的野百合碱-血红蛋白加合物为模板分子,经表面印迹聚合法制备野百合碱-血红蛋白分子印迹聚合物,用作固相萃取介质识别造模大鼠血液中的血红蛋白加合物。
结果理化性质表征结果显示聚合层成功接枝在碳纳米管表面,且聚合物具备良好的热稳定性;将聚合物作为固相萃取介质,对造模大鼠血液进行分析,结果显示聚合物血红蛋白加合物具有较强的吸附能力(吸附量达90.86mg/mg),该结果与肝脏病理检测结果呈正相关性。
结论所制备的聚合物可以快速分析体内血红蛋白加合物的含量,与肝脏病理结果相结合,为肝小静脉闭塞症的无创伤诊断提供新的研究思路。
关键词:野百合碱;血红蛋白加合物;分子印迹聚合物;肝小静脉闭塞症;无创诊断中图分类号:R917文献标识码:A文章编号:2096-3653(2024)02-0076-07DOI:10.16809/ki.2096-3653.2024011802Analysis of Monocrotaline-hemoglobin adducts in blood using molecularly imprinted polymersGE Yanhui1,2*,ZHENG Yuanru1,GUO Jingcan1,JIANG Zhihui1(1.School of Pharmacy,Guangdong Pharmaceutical University,Guangzhou510006,China;2.The First Affiliated Hospital, Guangdong Pharmaceutical University,Guangzhou510080,China)*Corresponding author Email:*****************.cnAbstract:Objective To establish a rapid analytical method for in vivo binding of monocrotaline and hemoglobin based on molecular imprinting technology.Methods The prepared monocrotaline hemoglobin adduct (Mct@BHb)was used as a template molecule to prepare molecularly imprinted polymers(Mct@BHb@MIPs)by using surface imprinting polymerization method,and then the Mct@BHb@MIPs were used as an extraction medium to adsorp toxic markers in rat blood.Results The results showed that the polymer layer was successfully grafted onto the surface of MWCNs,and the polymer exhibited good thermal stability after characterization.The Mct@BHb@MIPs were used as a solid-phase extraction medium to analyze the blood of model rats,and the results showed that the polymer hemoglobin adducts had good adsorption capacity(adsorption amount reached90.86mg/mg).The analysis results were consistent with liver pathological detection.Conclusio n The polymerprepared by this research can quickly analyze the content of hemoglobin conjugates in vivo,which provides new research ideas for non-invasive diagnosis of hepatic small vein occlusion,combined with pathological results.Key words:monocrotaline;hemoglobin adduct;molecularly imprinted polymers;hepatic veno-occlusive disease;non-invasive diagnosis含有吡咯双烷类生物碱(pyrrolizidine alkaloids,PAs)的中药在治疗疾病过程中易引发肝小静脉闭塞病(hepatic veno-occlusive disease,HVOD)[1],而目前我国有100多种含PAs的中药在临床上使用(约占《中药大辞典》收载量的1%),使得中药潜在的肝毒性问题不得不引起重视[2-3]。
Received 2005-12-16 Accepted 2006-01-04Note: This article is based on the Presidential Lecture given at IUPS 2005 in San Diego, California, USA. *Corresponding author. Tel: +1-414-4568277; Fax: +1-414-4566546; E-mail: cowley@Physiology and genomics: toward systems biologyAllen W. Cowley, Jr., Mingyu LiangDepartment of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USAAbstract: The last ten years have seen an unprecedented merge of physiology and genomics. While the field of physiological genomics is still very young, the introduction of the concept of systems biology promises to propel physiological genomics to a whole new level.In this brief article, we outlined some of the great opportunities and challenges for physiologists at this exciting time of physiological sciences, and used our own experience from the last ten years as an example to discuss how we could expand and go beyond the combination of physiology and genomics to achieve a systems understanding of biology.Key words: physiology; genomics; systems biology生理学与基因组学:走向系统生物学Allen W. Cowley, Jr., 梁明瑜威斯康星医学院生理学系,密尔沃基,威斯康星州 53226,美国摘 要:近十年来,生理学与基因组学达到了空前的融合。
What is Acceptance Criteria in GMP standard?Acceptance Criteria: The acceptable limits of a GMP Critical Parameter to ensure product SISPQ (Strength, Identity, Safety, Purity, or Quality). The criteria a product must meet to successfully complete a test phase or to achieve delivery requirements. This is usually associated with aperformance qualification. It may require an exact result (such as the ability of a bar code system to identify correct or incorrect codes) or it may state an acceptable range (such as an incubator demonstrating the ability to maintain a temperature set point plus or minus a given tolerance). What is Acceptance Criteria in GMP standard?Acceptance Criteria: The acceptance criteria are pre-defined and agreed standards, limits or ranges between different parties such as Quality Assurance and Quality Control or Manufacturing and Quality Assurance or suppliers.What is Active Pharmaceutical Ingredient (API) in GMP standard?Active Pharmaceutical Ingredient (API): An API also called Drug Substance (DS) is any physiologically active substance that is intended for use in a Drug Product. An API is alsoasubstance when used in the manufacturing, processing, or packaging of a drug, becomes an active ingredient or a finished Dosage Form of the Drug.What is Active ingredient in GMP standard?Active ingredient:Any component that is intended to furnish pharmacological activity or other direct effect in the diagnosis, cure, mitigation, treatment, or prevention of disease, or to effect the structure or any function of the body of man or other animals. The term includes those components that may undergo chemical change in the manufacture of the drug product and be present in the drug product in a modified form intended to furnish the specified activity or effect.What is Action Level in GMP standard?Action Level: The action level is a pre-defined and between different parties agreed written level. Once these levels are exceeded, actions must be undertaken. A complete investigation must be carried out and documented accordingly.What is Actual Yield in GMP standard?Actual Yield: The quantity that is actually produced at any appropriate phase of manufacture, processing, or packing of a particular API or intermediate.What is Adulterated Product in GMP standard?Adulterated Product: Adulterated Product is a Product or Medical Devices when it contains any filthy, putrid or decomposed Substance. This also applies for a Product or Medical Devices when it was prepared under unsanitary conditions or was not made in accordance with the GMPs. This could be also a Product or Medical Devices which contains an unsafe colour additive, or does not meet the requirements of an official compendium or Productregistration.What is API Starting Material in GMP standard?API Starting Material: A raw material, intermediate, or an API that is used in the production of an API and that is incorporated as a significant structural fragment into thestructure of the API. An API Starting Material can be an article of commerce, a material purchased from one or more suppliers under contract or commercial agreement, or produced in-house. API Starting Materials are normally of defined chemical properties and structure.What is Airlock in GMP standard?Airlock: A room or space designed to act as a means of segregating areas of different air classification or quality. It may contain a method to remove particulate contamination from clean room garments as personnel pass through, and usually includes HEPA filtered air supply and interlocking doors. Airlocks pressure will “float” between those of the spaces being protected. With all doors closed, the airlock pressure will be somewhere between that of the highest adjoining room and that of the lowest adjoining room as air flows through it from room to room. “Ventilated airlocks” are in neutral ducted air balance (supply CFM = return CFM).What is Alert Level in GMP standard?Alert Level: The alert level is a pre-defined and between different parties agreed written level. This level should be used to predict an action level. Once these levels are exceeded an investigation may not be necessary, but closer attention to the indicator is required.What is Analytical methods validation in GMP standard? Analytical methods validation: The process by which it is established, by laboratory studies, that the performance characteristics of the method meet the requirements for the intended analytical applications.What is Aseptic Technique in GMP standard?Aseptic Technique:Specific practices and procedures performed under carefully controlled conditions with the goal of minimizing contamination by microorganisms.What is Atypical Result in GMP standard?Atypical Result: An atypical result is a result which could be but must not be outside the pre-defined limit, however the result does not fit to the expectation or the normaldistribution of results. These results should be evaluated to predict any trends and to evaluate the significance.What is Authorized Person in GMP standard?Authorized Person: The authorized person in some European countries also called as qualified persons (QP) is the person(s) among key Manufacturing and Quality personnel responsible for GMP compliance and the release of every Batch of final Products.What is Batch (or Lot) in GMP standard?Batch (or Lot): A specific quantity of material produced in a process or series of processes so that it is expected to be homogeneous within specified limits. In the case of continuousproduction, a batch maycorrespond to a defined fraction of the production. The batch size can be defined either by a fixed quantity or by the amount produced in a fixed time interval.What is Batch Number (or Lot Number) in GMP standard? Batch Number (or Lot Number): A unique combination of numbers, letters, and/orsymbols that identifies a batch (or lot) and from which the production and distribution history can be determined.What is Bioburden in GMP standard?Bioburden: The level and type . objectionable or not) of micro-organisms that can be present in raw materials, API starting materials, intermediates or APIs. Bioburden should not be considered contamination unless the levels have been exceeded or defined objectionable organisms have been detected.What is Calibration in GMP standard?Calibration: The documentation that a particular instrument or device produces results within specified limits by comparison with those produced by a reference or traceable standard over an appropriate range of measurement.What is Challenge Condition in GMP standard?Challenge Condition: An extreme in the anticipated process parameters intentionally generated to demonstrate the ability of the process to meet the predetermined specifications throughout the operating range.What is Computerized System in GMP standard?Computerized System: A process or operation integrated with a computer system.What is Computer System in GMP standard?Computer System: A group of hardware components and associated software, designed and assembled to perform a specific function or group of functions.What is Contract Manufacturer in GMP standard?Contract Manufacturer: A manufacturer performing some aspect of manufacturing on behalf of the original manufacturer.What is Controlled Area in GMP standard?Controlled Area: An area constructed and operated in such a manner that some attempt is made to control the introduction of potential contamination, and the consequences of accidental release of living organisms. The level of control exercised should reflect the nature of the organism employed in the process. At a minimum, the area should be maintained at a pressure positive to the immediate external environment and allow for the efficient removal of small quantities of airborne contaminants.What is Cross-Contamination in GMP standard?Cross-Contamination: Contamination of a material or product with another material or product.What is Critical Process Parameters (CPPs) in GMP standard? Critical Process Parameters (CPPs): A measured variable that has a known effect upon a product quality attribute. A process parameter that must be controlled within a specified range to assure product quality.What is Critical Instruments in GMP standard?Critical Instruments: Equipment used to measure, monitor, and record a parameter that may have a direct impact on product quality.What is cGMP (Current GMP) in GMP standard?cGMP (Current GMP) :Current accepted standards of design, operation, practice, and sanitization. The FDA is empowered to inspect drug-manufacturing plants in which drugs are processed, manufactured, packaged, and stored for compliance with these standards. ( see also GMP)What is CIP (Clean In Place) in GMP standard?CIP (Clean In Place):Internally cleaning a piece of equipment without relocation or disassembly. The equipment is cleaned but not necessarily sterilized. The cleaning is normally done by acid, caustic, or a combination of both, with WFI rinse. The design of a CIP system should considered the operating volume design for the water consumption, chemical and biowaste effluent, and energy required to clean a given circuit or piece of equipment.What is Change Control in GMP standard?Change Control: A formal system by which qualified individuals of appropriate disciplinesreview and document proposed changes to assure that a validated state is maintained.What is Design Qualification in GMP standard?Design Qualification: Documented verification that the proposed design of equipment/systems is suitable for the intended purpose.What is Equipment Train in GMP standard?Equipment Train: The summation of all major pieces of equipment within a specific process.What is Exception in GMP standard?Exception: A departure for the Process Model or Study Plan as approved in the Protocol,Amendment or Addendum.What is Equipment Qualification in GMP standard?Equipment Qualification: Documented evidence by which a piece of equipment is certified to perform as per manufacturer specifications under controlled predetermined conditions.What is Installation Qualification (IQ) in GMP standard? Installation Qualification (IQ): Documented evidence by which equipment/systems are installed as per design specifications and manufacturer recommendations.What is Key Component in GMP standard?Key Component: A component that may impact the critical functionality of the equipment. What is Non-Process Related Error in GMP standard?Non-Process Related Error: One that is independent of the manufacturing process and where the cause is known.What is GMP?1. GMP definition ofGood Manufacturing Practices (GMP) for food additives are described in Section of the Preamble of the Codex General Standard for Food Additives as follows:“All food additives subject to the provisions of this Standard shall be used under conditions of good manufacturing practice, which include the following:a. The quantity of the additive added to food shall be limited to the lowest possible level necessary to accomplish its desired effect;b. The quantity of the additive that becomes a component of food as a result of its use in the manufacturing, processing or packaging of a food and which is not intended to accomplish any physical, or other technical effect in the food itself, is reduced to the extent reasonably possible; and,c. The additive is prepared an d handled in the same way as a food ingredient.”2. GMP definition ofGood Manufacturing Practice or GMP comprises guidelines for assuring the quality of production processes and the production environment during the production of, for example, pharmaceuticals and foods. A GMP-driven quality management system upholds product quality and satisfies the health authorities’ requirements which are obligatory for marketing.3. GMP definition ofGood Manufacturing Practice or GMP (also referred to as ‘cGMP’ or ‘current Good Manufacturing Practice’) is a term that is recognized worldwide for the control and management of manufacturing and quality control testing of foods, pharmaceutical products, and medical devices.What is GMP Facility in GMP standard?GMP Facility: A production facility or clinical trial materials pilot plant for the manufacture of pharmaceutical products. It includes the manufacturing space, the storage warehousefor raw and finished product, and support lab areas. A GMP facility operates under the guidelines established by the CFR (Code of Federal Regulations) Title 21, Parts 225 (Current Good Manufacturing for Medicated Feeds – Subpart B), and Part 226 (Current Good Manufacturing Practice for Type A Medicated Articles –Subpart B).What is Non-Critical Parameter in GMP standard?Non-Critical Parameter: Operating parameter that has been shown not to have an impact on the product and can be adjusted within an acceptable range while product is being manufactured.What is GMP Critical Parameter in GMP standard?GMP Critical Parameter: A parameter that has a direct effect on product quality.What is Good Engineering Practices (GEP) in GMP standard? Good Engineering Practices (GEP):“Established engineering methods and standards that are applied throughout the project lifecycle”. A combination of standards, specifications, codes, regulatory and industrial guidelines as well as accepted engineering and design methods intended to design, construct,operate, and maintain pharmaceutical facilities taking into account not only regulatory compliance but also safety, environmental protection and operability.What is Operating Range in GMP standard?Operating Range: A set of conditions encompassing upper and lower values actually permitted in the operation.What is Operational Qualification (OQ) in GMP standard? Operational Qualification (OQ): Documented evidence by which equipment/systems are functioning and operating at the intended operational parameters at which it will be used in production and/or manufacturer recommendations.What is Parenteral Drug (LVP, SVP) in GMP standard?Parenteral Drug (LVP, SVP): A parenteral drug is defined as one intended for injection through the skin or other external boundary tissue, rather than through the alimentary canal, so thatactive substances they contain are administered, using gravity or force, directly into a blood vessel, organ, tissue, or lesion. They are infused when administeredintravenously (IV), or injectedwhen administered intramuscularly (IM), or subcutaneously into the human body. A large volume parenteral (LVP) is a unit dose container of greater than 100ml that is terminally sterilized by heat. Small volume parenteral (SVP) is a “catch-all” for all non-LVP parenterals products except biologicals.What is Packaging Material in GMP standard?Packaging Material: Any material intended to protect an intermediate or API during storage and transport.What is Prospective Validation in GMP standard?Prospective Validation: Study where the adequacy of the process is determined by specific testing performed on critical steps in that manufacturing process prior to commercial manufacture of the product. Validation carried out before routine production of products intended for sale.What is Process system in GMP standard?Process system: The combination of equipment, support systems and procedures used to execute a process.What is Process Flow Diagram (PFD) in GMP standard?Process Flow Diagram (PFD): A diagram that shows key process steps and equipment.What is Process Assessment in GMP standard?Process Assessment: Assessment of a newly introduced process subsequent to technology transfer and prior to process validation for the purpose of demonstrating successful operation in the production environment with all normal production factors in place.What is Purified Water, in GMP standard?Purified Water, rendered suitable for pharmaceutical purposes by processes such as distillation,ion-exchange treatment (deionization or demineralization), or reverse osmosis. It meets rigid specifications for chemical purity, the requirements of the Federal Environmental Protection Agency (EPA) with respect to drinking water, and it contains no added substances. Cannot be used as raw material for parenterals. Common uses are: a rinse for equipment, vials, and ampoules, and as make upfor cosmetics, bulk chemicals, and oral products.What is Risk analysis in GMP standard?Risk analysis: Method to assess and characterise the critical parameters in the functionality of an equipment or process.What is Re-Validation in GMP standard?Re-Validation: A repeat of the process validation to provide an assurance that changes in the process equipment introduced in accordance with change control procedures do not ad-ersely affect process characteristics and product quality.What is Retrospective Validation in GMP standard?Retrospective Validation: Validation of a process for a product which has been marketed based upon accumulated manufacturing, testing and control batch data.What is SIP (Steam In Place) in GMP standard?SIP (Steam In Place):The introduction of steam to sanitize or sterilize a piece ofequipmentwithout relocating the equipment.What is Should in GMP standard?Should: Auxiliary verb indicating a lesser obligation to comply with the main verb that follows. Used when there is recognition that although bound by duty, there may be circumstances that warrant not proceeding as stated.What is System Life Cycle in GMP standard?System Life Cycle: The methodology that defines the phases through which a system passes from its conception to the termination of its use; ., the phases and activities.What is Specification in GMP standard?Specification: A list of tests, references to analytical procedures, and appropriate acceptance criteria that are numerical limits, ranges, or other criteria for the test described. It establishes the set of criteria to which a material should conform to be considered acceptable for its intended use. “Conformance to specifi cation” means that the material, when tested according to the listed analytical procedures, will meet the listed acceptance criteria.What is Technical Specification (TSP) in GMP standard? Technical Specification (TSP): The technical specifications defines all the engineeringrequirements needed to integrate the information contained in the P&ID’s, in order to clearly define the functional, mechanicals, and operational issues of the systems’ components.What is Unit Operation or Unit Process in GMP standard?Unit Operation or Unit Process: A single, discrete step that is typically a subdivision of the entire process and evaluated on its own merit.What is User Requirement Specifications (URS) in GMP standard?User Requirement Specifications (URS): The URS document defines “what” are the business and system requirements. General User Requirements are prepared in advance of the purchase of the equipment, and they define the requirements as needed by all of the user departments, which typically include Safety, Engineering, Production, Quality Control, and Validation. They are a description of what the equipment or system is supposed to do, and as such is normally written by the user.What is Worst Case in GMP standard?Worst Case: A condition or a set of conditions encompassing upper and lower processing or operating limits and circumstances, that should not necessarily result in product or process failure. The highest or lowest value of a given control parameter actually evaluated in a validation exercise.What is WFI (Water For injection) in GMP standard?WFI (Water For injection): WFI is water purified by distillation or by reverse osmosis, it contains no added substance. WFI meets the purity requirements under Purified Water. Although not intended to be sterile, it meets a test for a limit of bacterial endotoxin. It must be produced, stored, and distributed under Sterile Water for Injection.What is Variance in GMP standard?Variance: A failure to meetan acceptance criteria) or an Exception (departures form the Process Model or Study Plan included in the approved Protocol, Amendment or Addendum).What is Validation Protocol in GMP standard?Validation Protocol: A written plan stating how validation will be conducted and defining acceptance criteria. For example, the protocol for a manufacturing process identifies processing equipment, critical process parameters/operating ranges, product characteristics, sampling, test data to be collected, number of validation runs, and acceptable test results.What is Validation in GMP standard?Validation: A documented project that provides a high degree of assurance that a specific process, method, or system will consistently produce a result meeting pre-determined acceptance criteria. Establishing documented evidence, which provides a high degree of assurance that a specific process will consistently produce a product meeting its predetermined specifications and quality attributes.。
山 东 化 工收稿日期:2010-01-21作者简介:于大平(1956 ),男,高级工程师,主要从事炼油催化剂及分子筛生产经营工作。
分析与测试铝溶胶中铝含量电位滴定分析方法的建立于大平(中国石油化工股份有限公司催化剂齐鲁分公司,山东淄博 255300)摘要:以电位滴定分析方法原理为基础,通过考察滴定剂、滴定参数及缓冲剂等测定条件,建立了铝溶胶中铝含量的电位滴定分析方法,实现了滴定分析自动化,节约分析时间,提高分析准确度。
关键词:铝溶胶;铝组分;电位滴定分析中图分类号:O655.25;O614.31 文献标识码:A 文章编号:1008-021X(2010)04-0036-03The Establis h m ent of E lectro m etric T itration Analysis M ethod for Alu m inu m Content in A lu m inu m SolYU D a -p ing(SI N OPEC Cata lyst Co m pany Q il u D iv isi o n,Z i b o 255300,Ch i n a)Abst ract :Tak i n g electr i c potential titri m etr y m ethod pri n c i p le as basis ,built the poten ti o m tric titration analysis m ethod for t h e alu m inum co m tents i n a l u m inum so ,l realized the titri m etry auto m ation ,savedanalytical ti m e ,andi m proved ana l y tica l accurate degree through t h e fact tha t para m eter and buffer i n specti n g titrant,t h e titrati o n etc .deter m i n es conditi o n .K ey w ords :al u m inium so;l a l u m ini u m co mponen;t electro m etric titration ana lysis 1 前言铝溶胶是催化裂化催化剂目前常用的一种粘结剂产品,铝含量是表征产品质量的一项重要指标。
An Analytical Model for Buffer Hit Rate Prediction*Yongli (Lily) Xi, Patrick Martin and Wendy PowleyDept. of Computing and Information ScienceQueen’s UniversityKingston, OntarioK7L 3N6AbstractOf the many tuning parameters available in a database management system (DBMS), one of the most crucial to performance is the buffer pool size. Choosing an appropriate size, however, can be a difficult task. In this paper we present an analytical modeling approach to predicting the buffer pool hit rate that can be used to simplify the process of buffer pool sizing. Since the buffer replacement algorithm determines the buffer hit rate, we model the replacement algorithm which, in the case of DB2/UDB, is a variation of the GCLOCK algorithm. A Markov Chain model of GCLOCK is used to estimate the hit rate for a buffer pool. We evaluate the accuracy of the model’s estimates with experiments carried out on DB2/UDB with the TPC-C benchmark. The model is validated for both single and multiple buffer pool cases.1IntroductionToday’s database management systems (DBMSs) require database administrators (DBAs) to configure and tune the database to achieve optimal performance. However, since the tasks of configuring and tuning DBMSs are complex and time-consuming, there has been an increasing interest in self-tuning DBMSs, which shift some of the responsibility from the DBA onto the DBMS itself [1][6].The performance of a DBMS is greatly influenced by the effective use of main memory. A particularly important use of memory is the buffer area, which is a cache for data pages between database applications and the physical database files. It consists of* This research is supported by IBM Canada Ltd., Communications and Information Technology Ontario (CITO) and the National Science and Engineering Research Council.one or more buffer pools, and needs a buffer manager to transfer data between buffer pools and physical disk. Efficient use of the buffer area can reduce the number of disk accesses, which improves the system’s performance.Tuning the size of the buffer pool is therefore crucial to achieving good performance for a DBMS. Several heuristics exist to assist DBAs in this task but often fine tuning becomes a trial and error process. In this case, once the system is configured, the buffer pool hit rate(s) are monitored while the workload is running. If the hit rates are unacceptable, the system is reconfigured and monitored again. This process can be time consuming for a DBA. Our goal is to build an analytical model that can effectively predict buffer pool hit rates.The buffer hit rate depends on the buffer replacement scheme used by the DBMS. Least Recently Used (LRU) is a popular buffer replacement policy that gives good performance over a wide range of workloads, CLOCK and GCLOCK are also popular policies because of their simplicity and their ability to approximate the performance of LRU [4]. A variation of GCLOCK is used in IBM’s DB2 Universal Database (DB2/UDB) [5].In this paper, we present a model of the GCLOCK algorithm that is used to predict buffer pool hit rates for DB2/UDB. We extend an approach by Nicola, Dan and Dias [8], which develops an approximate analysis, using a Markov Chain model, for the GCLOCK policy under the Independent Reference Model (IRM). IRM applies to many database transaction processing workloads and assumes that each buffer page access is independent of all previous references. The Markov Chain model of GCLOCK is basedon a partitioning of the database by access frequency. We partition the database using information provided by the DB2/UDB trace facility [5].The remainder of the paper is organized as follows. Section 2 discusses the GCLOCK algorithm, the development of the Markov Chain Model and its solution. Our method of analyzing DB2/UDB trace data and predicting the buffer pool hit rate is described in Section 3. Section 4 compares our model’s predictions, for both single and multiple buffer pool configurations, with the hit rates achieved by DB2/UDB for the same workload. Section 5 draws conclusions and summarizes the paper.2Analytical ModelIn this section, the main algorithm and relative key issues are discussed. We start by looking at the GCLOCK buffer replacement scheme. Based on this algorithm, we introduce our Markov Chain model, the way we solve it, and the resulting equations used to predict buffer pool hit rates.2.1 GCLOCK AlgorithmConsider a database consisting of P partitions, such that the access to database pagesp P, and r p be the within a partition is uniform. Let s p be the size of partition p, 1≤≤probability of each access to a page of partition p. We assume that access to database pages follows the IRM model, that is, each page request is independent of all previous requests.All pages in the buffer pool are organized in a circular queue and each page has an associated counter. When a page from partition p is first loaded into the buffer its counter is assigned an initial weight, I p. When the system receives a request to access a page it first scans the buffer to find the requested page. If the page is already in thebuffer, that is, there is a buffer page hit, the counter associated with that page is set to the hit weight, H p . If the desired page is not in the buffer and the buffer is full then a buffer page must be selected for replacement. A clock pointer sweeps through the buffer pages,looking to replace the first page with zero count. On a page miss, the clock pointer points to the buffer page immediately following the page that was brought in for the previous miss. If the value of the counter associated with the page is zero then the page is selected for replacement, otherwise the counter is decremented and the next buffer page in sequence is examined. The process goes on until a page with zero count is found and selected for replacement. If the selected page is dirty then it is written out to disk before it is replaced. The new page is read into the buffer location and its counter is set to the initial weight, I p . The clock pointer advances to the buffer page immediately following the page that was replaced. Note that the clock pointer does not move on a buffer pool hit.We denote the maximum weight of partition p by L p , where L I H p p p =max(,).For simplicity, we assume that hit weight is equal to initial weight, that is, on a hit the counter of the buffer page is reset to the initial weight. In a research report done by Nicola, Dan and Dias, an extensive analysis is done for the case where the initial and the hit weights may not be the same [7].Suppose the size of the buffer pool is B pages. A buffer page, b i , B i ≤≤1, can be from any database partition p , P p ≤≤1, and will have a counter value in the range from 0 to L p , where L p is the maximum weight for that partition. Since each page in the buffer is a different distance from the clock counter, each page will be in a different state.Thus, if we build an exact Markov model for the GCLOCK policy, it will requireB L p p P+=∑11 states, which is a very large number. For example, for a buffer size of 1000pages, 4 partitions, and each partition with a maximum weight of 3, an exact model has 1048 states. Therefore, we need to resort to an approximate model. If we do not differentiate between buffer pages, that is, if we ignore the distance difference between buffer pages from the clock pointer, then we can build a simplified Markov model having the number of states equal to ()L p p P+=∑11[8].2.2 Markov Chain ModelThe objective of the model is to first determine the buffer hit probability h p for each partition, and then to evaluate the overall buffer hit rate. The buffer hit rate for partition p is the probability that pages from partition p that are brought into the buffer at steady state. Let N p be the steady-state average number of pages of partition p in the buffer, and let s p be the size of this partition, in pages. Then the buffer hit probability for this partition isp pp s N h =. (1)If we define r p as the probability of accessing the p th partition, the hit probability for the overall database is thenh r h p p p P==∑1.(2)2.2.1 Defining the ModelA list of the symbols used in the model is given in Table 1. As stated earlier, our approximate model has ()L p p P+=∑11 states. The Markov chain for this model represents the states of an arbitrary buffer page at the instant of a random page request. We use (p,i), where P p ≤≤1, 0≤≤i L p , to represent a state that corresponds to a buffer page of partition p , with a count i . In other words, the steady state probability of being in state (p,i) is the probability that an arbitrary buffer page is of partition p and has a count i . A portion of this Markov chain model, which corresponds to partition p , is shown in Figure1. The complete Markov chain includes all partitions and, since the partitions are similar,we can extend the analysis for partition p to the Markov chain corresponding to the whole database. The transitions among the parts of the Markov chain (corresponding to different partitions) occur only through the two end states, (p, 0) and (p, L p ), 1≤≤p P ,as shown.System parametersP Number of data partitionss p Size of partition p (in pages)r p Probability of accessing the p th partitionI p Initial weight assigned to partition pH p Hit weight assigned to partition pL p max(I p , H p )B Buffer size for this partition (in pages)Model variablesh p Hit probability of partition pm p Miss probability of partition ph Overall buffer hit probability for this partitionm Overall buffer miss probability for this partitionn p,i Average number of buffer pages that come from partition pwith count in 0Average number of buffer pages with count 0N p Average number of buffer pages that come from partition pTable 1: List of symbols and their meaningsp /s pFigure 1: Markov Chain Model for Partition pLet n p,i be the steady-state average number of buffer pages that come from partition p with count i , 0≤≤i L p . Summing the number of buffer pages of partition p with all possible count values we get N p , which is the average number of buffer pages that all come from partition p . That is∑==p L i i p p n N 0,, where Pp ≤≤1(3)We denote n 0 to be the average number of buffer pages with count zero from all partitions at steady state. In a similar manner as with N p , we can derive n 0 by summing all buffer pages from any database partition having zero count. Thus we have<2>∑==P p p n n 10,0(4)We define a clock cycle as a complete rotation of the clock pointer through all pages in the buffer. From our previous discussion of the GCLOCK model, we can see that at each buffer pool miss, the clock traverses buffer pages until it finds a buffer with count zero. As outlined earlier, when such a buffer miss occurs, the clock points to the buffer page immediately following the last page read from disk. So in a complete clock cycle, the number of buffer misses equals the number of buffer pages with a zero count encountered during that cycle.2.2.2 Transition Relationships DerivationWe are now ready to discuss the transition relationships between all model states and we justify the probability of transition from one state to another as shown beside the edges in Figure 1. For clarity, we divide the transition relationships into 4 groups, labeled <1>,<2>, <3> and <4> in Figure 1, and discuss them individually.In the model, the basic approximation assumes that the average number of misses in a complete cycle of the clock is equal to the average number of buffer pages with zero count at steady state, n 0. This is an approximation because pages with zero count may have been hit and converted to pages with a non-zero count, during the time the clock pointer makes one pass of the buffer. Nicola, Dan and Dias [8] claim that this type of page request is typically a small portion of the total requests. Our experiments also verified that the impact of this assumption is not significant.Given that the number of misses in a cycle of the buffer is n 0, then the probability that a particular page’s counter is decremented on a miss is 10n . Therefore, for anarbitrary page request, the transition probability from state (p, i) to state (p, i-1) is m n 0,0≤≤i L p , where m is the overall buffer miss probability. Note that the probability of a transition out of state (p, 0) due to a miss is also m n 0, which corresponds to the probability of replacing an arbitrary buffer page having a zero count. This justifies the group <1>transition.We defined the probability of accessing a partition p to be r p , and the size of partition p to be s p . In other words, there are s p pages in this partition, and they altogether have access probability r p . Thus an arbitrary page of partition p is requested with probability p ps r . As stated earlier, whenever a page is hit, the desired page has alreadybeen brought into the buffer and its counter is reset to L p . The transition probability fromany state (p, i), 01≤≤−i L p (), to state (p, L p ) is therefore pp s r . This justifies the group <2> transition.We now derive the group <3> relationship. For a given buffer page request, the probability that a page will be brought into the buffer is equal to the probability that a page request causes a buffer page miss, that is, m p . Since the probability of accessing the p th partition on a certain request is r p , the probability that a page of partition p is brought into the buffer is r p m p . Also, given that the probability a miss will happen for the wholedatabase is 10n , and that once a page is brought in, its count is reset to the maximum weight, the transition probability from each of the states (p, 0), 1≤≤p P , to state (p, L p )is thus r m n p p0. Note that a buffer page from any partition with zero count may be replaced by a particular partition page. r m n p p0 is thus the transition relationship from all other partsof the Markov chain to the particular partition we are discussing. This justifies group<3> of transition relationships in the figure, namely the transitions from states (1, 0)through (P, 0) to state (p, L p ).Likewise, a page from partition p may also be replaced by a page from any other partition. Using the same justification as in group <3> we can easily derive transition probabilities in group <4>, that is, for the set of arrows pointing from state (p, 0) to state (1, L 1) through state (P, L P ), which are 0n m r i i respectively. (i, L i ) denotes the state of a page which is from partition i with maximum weight L i . This is the probability of a transition out of state (p, 0) to the states related to buffer pages of any partition (includingitself of course) due to a miss. We observe that r m n r m n r m n m n p p 11022000+++=, which conforms to our earlier justification in group <1> that the transition probability out of state (p, 0) on a buffer page miss ism n 0.2.2.3Solving the ModelGiven that the buffer size is B , and number of buffer pages from partition p with count i is denoted by n p,i , we define π(p, i), the steady-state probability of a page being in state (p,i) as π(,),p i p in B=We now write the Kolmogorov’s Forward Equations of the Markov chain,balanced at state (p, i). Referring to the Markov chain model shown in Figure 1, we see that there are two outgoing paths for any inner state (p, i), of the model, 0<i<L p . One edge goes to state (p,i-1), and the other goes to state (p, L p ). The rates associated with the outgoing edges arem n 0 and pp s rrespectively. There is also one entering path, with rate mn 0from state (p, i+1). For some steady state (p, i), the number of buffer pages leaving the state should equal to the number of buffer pages entering the state. The steady state probability of a page being in state (p, i), π(p, i), can be also viewed as the portion of the page’s lifetime that it is in state (p, i). The rate of buffer pages leaving the state can therefore be expressed as ()(,)m n r s ppp i 0+π. Likewise the rate of buffer pages entering state (p, i) can be expressed asm n p i 01π(,)+. Thus we have:()(,)(,)m n r s mn p p p i p i 001+=+ππUsing the same idea, we can derive the balance equation for the “end-state” (p,L p ). As shown in Figure 1, the outgoing transition from this state has a raten m. There are two sets of incoming transitions into the state. One set has a rate ofn m r pp , and the other set has a rate ofpps r . We therefore get the following equation∑∑−==+=10),()0,(10),(0p L i i p ppi P i p p Lp p sr n m r n mπππ, where Pp ≤≤1Thus,p pp p p L p p pN s r m r n s r n m p +=+,0)(We can then derive the general relationship,0,)1(p ipp i p n s r m n n +=(6)and,ms r m n n r n p L pp p p 1000,)1(++=(7)N p can thus be derived:))1(11(10++−=p L pp p p s r m n s N , where Pp ≤≤1(8)Since all pages in buffer must sum to the buffer size B, we haveB NPp p=∑=1(9)We finally get a nonlinear equation,))1(11(110=−+−∑=+B s r m n s Pp L pp p p (10)which is the key equation in our approach to estimating buffer hit rate.We note that the quantities m and n 0 always appear together as the ratiomn 0, and so can be looked on as one variable. Equation (10) can be solved iteratively for the ratio mn 0using the bisection method [2], which according to our experiments, converges very quickly. Once the ratiomn 0is determined, we can evaluate N p , P p ≤≤1, from equation (8), and h p , the buffer hit probability for each partition from equation (1). Finally we can compute the overall hit probability for the whole database, using equation (2).3 Method to Predict Hit RatesFrom the derivation of the Markov model, we can see that, given a certain buffer size, we need the following input values to estimate the hit rate for a specified buffer area:P Number of data partitions s p Size of partition p (in pages)r p Probability of accessing the p th partition L p maximum weight, which is max(I p , H p ) I p Initial weight assigned to partition p H pHit weight assigned to partition pAccording to our assumptions, L p = I p = H p , so the last three inputs can be looked on as one parameter.3.1Partitioning Criteria and ApproachWe first need to partition the database such that the access frequency to database pages within a partition is uniform. There are various ways to define "uniform". For example,it can mean the same access frequencies or the same access patterns. Dan [3]distinguishes three types of access patterns, namely, 1) locality within a transaction, 2) random accesses by transactions and 3) sequential accesses by long queries.Our experimental workload is generated by the TPC-C OLTP benchmark. OLTP workloads in general, and TPC-C specifically, have few sequential accesses. This means that partitioning based purely on access pattern is not suitable. It is also the case that, for multiple buffers, one criteria often used to configure database objects to buffer pools is the access pattern for those objects. A buffer pool may therefore only reflect one type of access pattern. OLTP workloads typically have skewed (non-uniform) data access, that is, we can identify a set of "hot" pages that receive a greater portion of the accesses. This property of OLTP workloads can be adequately modeled by partitions based on access frequency [3].3.2Disk/Memory Reference TraceIn order to collect detailed information on page access frequencies, we trace each page access by a transaction for a sample run of the workload. OLTP workloads are almost always cyclic in nature [3], so a large enough sample will adequately reflect the complete set of pages accessed by that workload. Since the buffer area sits in the middle of the memory hierarchy, all table accesses have to go through buffer pool. Tracing the buffer pool references thus provides the required information on database references.We need to trace every read and write access to the buffer pools and to record the physical page number and database object accessed. The DB2/UDB trace facility provides this information. For each buffer pool reference, whether it is a read or a write, we can trace two activities. The system issues a FIX to fix a page before an access, and an UNFIX after the access is completed. From the trace we obtain the object pagenumber for each page accessed which is the address of the page relative to the start of the object.3.3Database PartitioningIn our experiments, we observed that the accesses were concentrated on a small number of database pages, and a relatively large part of the database pages get only a few access requests. In a typical experimental run, 3% of the distinct pages account for 80% of the total database accesses. On the other hand, over half of the database pages only get around 3% of the accesses. It is thus straightforward to group database pages based on access frequencies.We divided the database into four partitions based on access frequency. We call these partitions "hot"-- most frequently accessed pages, "cold" -- rarely accessed pages, "warm" -- pages whose access frequency falls in between and “freezing” – unused database pages. Since the pages in the freezing partition have a 0% probability of being accessed, we ignore these pages in our analysis and only consider the other three partitions.Three types of counters are maintained. For the single buffer pool case, we count the distinct pages the system has accessed during the testing period, that is, the number of distinct pages (S) that have appeared in the trace file. We also count the number of accesses associated with each distinct page (a i), and the number of overall accesses (A). After partitioning, we can add up the number of distinct pages in each partition to getsp the size of each partition. We can also get the number of overall accesses in one partition by using∑==ps i ip a a 1We can then calculate the overall access probabilities for each part asAa r p p =Note that ∑==Pp p S s 1, remembering P is the number of the partitions, and S is the overalldatabase size. The maximum weight for each database partition L p , is assigned the value 2 since DB2/UDB uses weight values of 0, 1, or 2 to indicate the locality of a page.For the multiple buffer pool case we treat each buffer pool and its associateddatabase objects as an individual small database. In this way, we split the multiple buffer pool case into several single buffer pool problems. We collect the necessary model inputs for, and apply our analytical model to, each of them. Experiments for both the single and multiple buffer pool cases are presented in Section 4.4 ExperimentsAll the experiments were run with DB2/UDB Version 7.1 under Windows NT on an IBM Netfinity 5000. The machine was configured with one 400 MHz processor, 1 GB of RAM and 5 disks. The workload used in the experiments is the TPC-C benchmark,which typifies an OLTP workload [9]. The database schema from the TPC-C benchmark is composed of nine relations. TPC-C simulates the activities of a wholesale supplier and includes 5 order-entry type transactions. The database we use has 10 data warehouses,each of which is approximately 100MB bytes in size. Thus the database has about 250,000 4K pages. In our experiments, 40 clients, or simulated “terminal operators”issue the transactions against the database. The relative frequencies of each transaction are as specified in the benchmark.4.1System Performance MonitoringIn order to validate and evaluate our buffer hit rate estimates, we collect real buffer hit rates under different buffer configurations to compare with our model estimation. For each configuration, we let the TPC-C driver run for 5 minutes to allow the system to stabilize. Each time we run the TPC-C driver for a specified configuration, we collect "snapshot" data five times. The buffer hit rate for each snapshot is calculated, and the average of the snapshots is used to get the average hit rate for a run. Each snapshot period is 8 minutes long. We use the mean from each configuration as the final system figure in our model comparison studies. A statistical analysis of the results reveals that the system performance is quite stable. A confidence level of 95% is used in the analysis.Each of our trace files contains about 12,000 trace records. Since we need a trace file as long as possible to ensure reliable and complete data, we collect a long series of trace files, and then concatenate them into a single file of over 600 minutes worth transactions and a size of 136 MB.Our experiments showed that the number of distinct pages accessed from the 136-MB trace file is not significantly more than that from a 60-MB trace file. Although the first file is almost twice the size of the second, it contains less than 50 more distinct pages than the smaller file, compared to the 3438 pages in total. This means that the access to the database is very concentrated on a part of the pages in TPC-C activities and that the workload is cyclic as assumed.Our analysis of the trace file showed that there are 3438 distinct pages accessed, and the total number of accesses is 183770. When studying the distribution of access frequencies, we see that 80% of the total page accesses are concentrated on roughly 2% of the distinct pages accessed. Over half of all distinct pages are accessed less than 4 times. We can easily distinguish the "hot" and "cold" partitions, and the pages in between can be treated as the "warm" partition.We tried various partitioning schemes on the accessed pages, which are shown in Tables 2 through 4, to evaluate the impact of the partitioning criteria on the performance of our approach.Partition Size(pages)Percentage ofdatabaseNumber ofTotal accessesAccessprobabilityHot (>250 requests)820.023*********.8050 Warm(5~250 requests)14880.43282300880.16377 Cold (<5 requests)18680.5433357390.03123Table 2: Partitioning Plan 1Partition Size(pages)Percentage ofdatabaseNumber oftotal accessesAccessprobabilityHot (>250 requests)820.023*********.8050 Warm(4~250 requests)25120.73066341840.18606 Cold (<4 requests)8440.2454916430.00894Table 3: Partitioning Plan 2Partition Size(pages)Percentage ofdatabaseNumber oftotal accessesAccessprobabilityHot (>150 requests)1000.029*********.82474 Warm(4~150 requests)24940.72542305650.16632 Cold (<4 requests)8440.2454916430.00894Table 4: Partitioning Plan 3When partitioning the database, we attempted to find the smallest partition that was most frequently accessed. In this way, the hottest partition, which is relatively small in size, is almost guaranteed to remain buffered in the memory given that the buffer is large enough. We found experimentally that the estimates produced from the first partitioning plan were closest to the system performance. Therefore we use partitioning plan 1 as the initial input to our analytical model.4.2 Single Buffer Pool ExperimentFigure 2: Single Buffer Pool Hit RateHit rate values collected from the real system and estimated from the model for a single buffer pool of 400 to 2400 4K pages are shown in Figure 2. We can see that the two curves almost coincide with each other, except for small differences when the buffer size is very large compared to the total amount of the database that is accessed. However, our comparison result shows that the difference between our model result and the real system performance is not significant. On average, the estimated error is around 2%. Thus we。