Lattice dynamics study in PbWO4 under high pressure

㊀第40卷㊀第11期2021年11月中国材料进展MATERIALS CHINAVol.40㊀No.11Nov.2021收稿日期:2020-02-23㊀㊀修回日期:2020-05-04基金项目:国家自然科学基金项目(81722015,81870805,81870787);陕西高校青年创新团队项目第一作者:王婉蓉,女,1992年生,医师秦㊀雯,女,1998年生,在读本科生(八年制)通讯作者:牛丽娜,女,1983年生,教授,博士生导师,Email:niulina831013@ 焦㊀凯,男,1982年生,副教授,博士生导师,Email:kjiao1@DOI :10.7502/j.issn.1674-3962.202002009细菌介导生物矿化的研究进展王婉蓉1,秦㊀雯1,顾俊婷1,郑秀丽1,唐笑怡2,焦㊀凯1,牛丽娜1(1.军事口腔医学国家重点实验室口腔疾病国家临床医学研究中心陕西省口腔医学重点实验室第四军医大学口腔医院修复科,陕西西安710032)(2.中国人民解放军联勤保障部队第九二ʻ医院(昆明医科大学教学医院),云南昆明650032)摘㊀要:生物矿物因其高度有序的结构和良好的机械性能成为诸多学科研究的热点㊂对细菌㊁真菌㊁病毒等微生物介导生物矿化的深入研究,不仅能使学者更加系统地认识生命演化过程,而且能为新材料的研发提供思路㊂其中,细菌诱导的矿化因其潜在的应用价值而深受研究者的青睐㊂首先介绍了细菌介导的钙化㊁硅化㊁铁矿化3种不同的生物矿化类型,其次讨论了细菌介导生物矿物形成的可能机制,最后阐述了生物矿物在环境㊁工业及医疗领域的应用,为进一步的生物矿化研究奠定基础㊂关键词:生物矿化;生物矿物;细菌;环境;工业;医药中图分类号:R783.1㊀㊀文献标志码:A㊀㊀文章编号:1674-3962(2021)11-0930-08Progress of Bacteria-Mediated BiomineralizationWANG Wanrong 1,QIN Wen 1,GU Junting 1,ZHENG Xiuli 1,TANG Xiaoyi 2,JIAO Kai 1,NIU Lina 1(1.State Key Laboratory of Military Stomatology &National Clinical Research Center for Oral Diseases &Shaanxi Key Laboratory of Stomatology &Department of Prosthodontics,School of Stomatology,The Fourth Military Medical University,Xi a n 710032,China)(2.Kunming Medical University,920th Hospital of Joint Logistics Support Force,Kunming 650032,China)Abstract :Biominerals have become hotspots in many disciplines due to their highly ordered structure and good mechanicalproperties.The research on microbe-mediated biomineralization can help us to understand the evolution process of life more systematically,and provide new ideas for the development of new materials.Among them,bacteria-mediated biomineraliza-tion is favored by researchers for its potential value.Firstly,this article introduces the processes of calcification,silicifica-tion and iron mineralization induced by bacterial.Then,we discuss the possible mechanisms for bacterial-mediated biologi-cal mineral formation.Finally,we describe the application of biominerals in the environmental,industrial,and medical fields.It is expected that this study may help the further development of biomineralization.Key words :biomineralization;biominerals;bacterial;environment;industry;medicine1㊀前㊀言生物矿化是指生物体通过蛋白质等生物大分子调控无机矿物形成的过程㊂在此过程中形成的具有纳米级结构的生物矿物,不仅具备极佳的强度和断裂韧性,也呈现出良好的生物相容性㊂迄今为止,已从生物中鉴定出60多种不同的矿物质㊂这些矿物对于自然界的物质循环起着重要作用[1]㊂细菌作为自然界最活跃的微生物之一,在生物矿物的形成中发挥着重要的作用㊂目前已经发现了大量由细菌介导生成的矿物,例如有研究发现嗜盐菌及枝芽孢菌可以促进白云石的形成;球形芽孢杆菌有助博看网 . All Rights Reserved.㊀第11期王婉蓉等:细菌介导生物矿化的研究进展于碳酸钙晶体的形成[2]㊂细菌介导的矿化与生命演变息息相关㊂在原始环境下最早出现的是原核生物矿化,这表明细菌-矿物相互作用是生命史早期的一个重要现象㊂这种相互作用对于古老地球环境的研究以及寻找其他行星表面生命都有着重大意义[3]㊂当外界环境转变至有利于矿化发生时,细菌通常有着多种不同的应答方式,例如通过形成生物膜避免被矿化或在保存细菌活性的前提下嵌入矿物中,甚至可在矿物形成过程中控制其形态㊂此种现象说明细菌的进化与周围环境的改变息息相关[4]㊂相比于化学合成的方式,细菌合成矿物不仅绿色经济环保,且操作较为方便,因此细菌介导的生物矿化在环境净化㊁工业生产和医药研究等领域的潜在应用已成为目前研究的热点㊂例如一些由微生物矿化引起的疾病有可能通过对细菌的干预进而治愈[5];由于生物矿物具有良好的生物相容性,因此可作为药物载体应用在肿瘤疾病的靶向治疗中[6];除此之外,可通过化学交联和基因编辑等方式修饰细菌蛋白,使生物矿物的形态和大小根据工业需要进行合成[7]㊂本文综述了细菌介导生物矿化的类型㊁作用机理及应用,为进一步的生物矿化研究提供参考㊂2㊀细菌介导生物矿化的类型2.1㊀钙化细菌介导的钙化存在于天然矿物和生物体内㊂研究发现好氧菌如Salinivibrio和Virgibacillus有助于MgCa-(CO3)2的形成,而MgCa(CO3)2被认为是天然矿物白云石的前体[8]㊂甲壳类动物㊁海洋生物㊁植物甚至人体组织均可见由细菌介导的钙化发生㊂甲壳类动物是指虾㊁蟹等有坚硬外壳保护的动物,其外壳由甲壳质㊁结合蛋白和碳酸钙构成,具有排泄㊁感知和保护的作用[9]㊂研究发现甲壳类动物Titanethes albus的钙体内存在大量细菌,且钙体的中心存在结晶晶核[10]㊂海绵是一种海洋无脊椎动物,体内存在多种钙化细菌,这些细菌可产生钙化小球覆盖在海绵表面,模拟外周骨骼结构,保护海绵免受外界的伤害,从而提高海绵存活率[9,11]㊂细菌介导的钙化也存在于人体组织中㊂有研究证实尿路结石的发生可能与假单胞菌㊁乳酸菌及肠杆科菌有关㊂细菌导致尿路结石产生的可能机制有以下3种:细菌选择性地聚集在草酸钙晶体上使钙盐增长变快;细菌释放柠檬酸裂解酶,降低尿液中柠檬酸水平的同时提高草酸盐浓度,从而导致尿液过饱和,致使结晶形成;细菌-晶体聚集体可与肾小管上皮结合,导致肾小管上皮或炎性细胞中结石基质蛋白的表达,从而形成结石[5]㊂细菌诱导的钙化也可发生在极端环境下㊂Planococcus halocryophilus Or1在-15ħ时可使调控碳酸钙矿化的碳酸酐酶表达升高,导致更多的碳酸钙沉积在细菌细胞膜中[12]㊂2.2㊀硅化除钙化之外,细菌亦参与了自然界的硅化过程㊂据报道,在ImawarìYeuta洞穴中发现的无定形二氧化硅是由丝状细菌蓝藻介导产生的㊂蓝藻的代谢产物使洞穴环境pH值升高,致岩石溶解㊂溶解产生的二氧化硅可在细菌细胞膜上以无定形的形式重新沉淀[13],形成管状及丝状的岩石结构㊂另外,蓝藻的硅化作用有助于化石在形成过程中保存完好的细胞结构,使考古学家可以获得更多有关古生物的生命信息[14]㊂2.3㊀铁矿化多种细菌都可介导产生四氧化三铁(Fe3O4)和硫化铁(Fe3S4㊁Fe1-x S㊁Fe9S8),其中趋磁细菌(magnetotactic bacteria,MTB)是目前研究的热点㊂MTB是一种能够沿着地球磁场运动或排列的原核生物[15]㊂目前已知的多数MTB属于α-蛋白菌㊁δ-蛋白菌㊁γ-蛋白菌和硝化螺菌类[16],均为革兰氏阴性细菌,有球形㊁弧形㊁杆形及螺旋形等多种形态㊂MTB中负责趋磁运动的细胞器是由细菌生物矿化合成的磁小体㊂磁小体由脂质双分子膜包裹的纳米级磁铁矿晶体构成[17],是淡水沉积物中的重要天然磁性元素㊂这些磁性纳米晶体具有粒度均一㊁纯度高㊁磁性强和生物相容性良好等特点㊂磁性纳米颗粒在自然界中发挥着重要作用㊂由于产生胶黄铁矿的MTB需要硫才能合成磁小体,因此胶黄铁矿被认为是地质历史上停滞缺氧状态(一种无氧状态,由于游离H2S水平升高而呈硫化物状态)的指标[18]㊂此外,在微生物的进化过程中,环境中氧气的出现给微生物带来了源于活性氧的毒性,而嗜热性嗜酸菌Sulfolobus solfa-taricus能够通过氧化作用将Fe2+氧化成Fe3+形成铁矿物,这可以认为是原始生命对于氧气环境的适应[19]㊂另外人体组织中的磁性纳米颗粒与众多疾病的发生发展有关㊂有研究在多种人体器官中均发现了磁性纳米颗粒的存在,其中小脑和脑干分布较多[20]㊂由于这些磁性颗粒与MTB 产生的晶体较为相似,因此被认为其来源为MTB㊂研究发现磁性氧化铁纳米颗粒在中枢神经系统细胞(尤其是星形胶质细胞)的过度积累可能导致正常的铁代谢紊乱,这是神经退行性疾病产生的一个标志性特征,但具体的机制有待于更进一步的研究[21]㊂3㊀细菌介导生物矿化的发生机制自然界的生物矿化可分为生物诱导矿化和生物控制矿化㊂生物诱导矿化是由生物的生理代谢活动引起环境139博看网 . All Rights Reserved.中国材料进展第40卷条件变化而发生的矿化,其中,生物不能直接控制沉淀物的产生位置或产生方式(图1a)㊂生物控制矿化是由生物的生理活动引起的,可产生高度有序的沉淀物,且沉淀物大小㊁质地和方向受生物体控制(图1b)[22]㊂图1㊀生物诱导矿化(a)和生物控制矿化(b)的示意图[22]Fig.1㊀Schematic representation of biologically induced mineralization (a)and biologically controlled mineralization (b)[22]㊀㊀根据发生位置的不同,细菌介导的矿化可分为细胞外矿化和细胞内矿化㊂细胞外矿化是指发生在细胞周围基质中的矿化㊂细胞可通过细胞膜上的蛋白质将阳离子泵出,或通过分泌含有阳离子的囊泡,介导周围基质的矿化㊂细胞内矿化则是指由细胞的代谢活动介导的胞内囊泡矿化㊂细胞内矿化的产物可以存在于细胞内(如MTB),也可以通过胞吐作用释放到胞外(如硅藻)㊂矿化的基本化学反应过程为羧基㊁磷酸基团㊁胺基和羟基等带负电荷的基团与金属阳离子结合,形成矿物㊂以钙化物羟基磷灰石(hydroxyapatite,HAP)为例,其基本的化学反应过程如下:10Ca(OH)2+6H 3PO 4ңCa 10(PO 4)6(OH)2+18H 2O3.1㊀细胞外矿化3.1.1㊀初始矿化细胞外矿化发生的首要条件是细菌周围有足够的可溶性离子㊂研究发现,细菌可通过多种不同机制增加可溶性离子的浓度,例如大肠杆菌在碱性磷酸酶的作用下可以释放磷酸根离子[23],浮生细菌可以通过分泌酸(羧酸㊁盐酸等)降低环境中的pH 值,从而溶解无机磷酸盐㊁增加可溶性离子[24]㊂初始矿化阶段可由经典结晶理论和非经典结晶理论来解释(图2)[25]㊂经典结晶理论认为,成核是相变的开始,这个过程是不可逆的㊂在细菌矿化过程中,成核位点位于胞外聚合物(extracellular polymeric substances,EPS)或细菌表面蛋白质上㊂EPS 由细菌分泌的大分子构成,包含了多糖㊁蛋白质㊁DNA㊁脂类等物质㊂由于EPS 中的大分子物质含有羧基㊁磷酸基团㊁胺基和羟基等带负电荷的基团,EPS 降解后,可与局部过饱和的阳离子相互结合引起矿物沉淀[26]㊂当成核位点位于细菌表面蛋白质上时,金属阳离子如铁离子可直接与细菌表面蛋白质中的羧基和羟基反应,通过金属氧化反应形成金属-蛋白质复合物[27]㊂图2㊀经典结晶理论及非经典结晶理论示意图[25]Fig.2㊀Schematic diagram of classical nucleation theory and non-classical nucleation theory [25]239博看网 . All Rights Reserved.㊀第11期王婉蓉等:细菌介导生物矿化的研究进展㊀㊀而非经典结晶理论认为晶体的形成是以粒子为媒介,由动力学控制的㊁与相分离无关的结晶过程㊂在溶液中首先形成具有弥散边界的无定形离子簇,称之为预成核簇(pre-nucleation clusters,PNC)㊂PNC是热力学稳定的聚集体,可存在于各种不饱和或超饱和溶液中[28]㊂接着,PNC聚集形成无定形矿物前体,在碳酸钙形成过程中的无定形矿化前体为无定形碳酸钙(amorphous calcium carbonate,ACC)[29],在磷酸钙形成过程中的无定形矿化前体为无定形磷酸钙(amorphous calcium phosphate, ACP)[30],继而无定形矿化前体失去结合水,经过固态转化结晶[31]㊂更进一步的研究认为,这种生物矿化过程发生在由特定蛋白质形成的水凝胶环境中,其特有的内部孔隙充当 有限体积的反应容器 ,可以促进无定形矿化前体的形成[32]㊂3.1.2㊀晶体生长晶体生长过程决定了最终晶体的大小和形态㊂和初始矿化相似,晶体生长也可以通过经典结晶理论和非经典结晶理论来解释㊂经典结晶理论认为,在高过饱和溶液中以成核为主,而在低过饱和溶液中晶体生长占主导地位[33]㊂在这一过程中依据的是奥斯瓦尔德现象,即在溶液过饱和的情况下,热力学能量驱动单个原子或分子沉积在成核部位,使材料有序排列生长成稳定的晶体结构㊂溶液中不同的添加剂和物理参数会导致每个单晶面的生长速率不同,从而形成形态各异㊁大小不一的晶体[34]㊂非经典结晶理论认为,矿化前体无定形碳酸钙或无定形磷酸钙通过定向附着形成介晶结构,继而在蛋白质的引导下组装聚集成为晶体结构㊂在此过程中,蛋白质发挥着重要作用㊂例如海胆脊椎基质蛋白SPSM50不仅可增强无定形矿化前体的稳定性,而且以介晶结构的形式诱导了晶体的定向生长[35]㊂3.2㊀细胞内矿化细胞内矿化是指用于细胞内矿化的离子在转运蛋白的作用下被富集至囊泡中,继而发生矿化[36]㊂细胞内矿化与细胞外矿化最大的不同在于有囊泡的参与㊂在此过程中,囊泡膜上的蛋白质以及囊泡内的蛋白质不仅为矿化提供成核位点,也形成了一个 有限体积 以实现蛋白质等分子的集中,称为分子拥挤(molecular crowding)㊂在结晶发生前,一些分子(如聚乙二醇)会抑制矿物前体的形成和自我聚集;在结晶发生时另一些大分子(如牛血清白蛋白)则会促进矿化前体的聚集[37]㊂这一过程也是仿生矿化中的研究热点㊂MTB诱导的铁矿化是细胞内矿化的典型代表㊂其在磁小体内产生纳米级别铁磁性颗粒的可能机制如下(图3)[38]:首先细胞质膜(图3a)内陷形成囊泡(图3b),其次转铁蛋白将铁离子(经细胞)转运到囊泡中㊂包裹Fe2+图3㊀磁小体的形成过程[38]Fig.3㊀The formation process of magnetosomes[38]339博看网 . All Rights Reserved.中国材料进展第40卷的囊泡与细胞骨架接触时,Fe2+氧化成为Fe3+,膜上的蛋白质启动成核,并且调控囊泡内矿化形成磁铁矿晶体(图3c),称之为磁小体㊂磁小体膜上的蛋白质可与肌动蛋白相互作用,使磁小体成链状排列(图3d)㊂随后,在细胞分裂过程中细胞壁通过弯曲磁小体链减少磁力,促进磁小体均匀地分离到子细胞中(图3e和3f)㊂研究表明,MTB基因组上有一段特殊的区域,称为磁小体岛(图3g),该基因岛与磁小体的形成密切相关㊂相关基因如mms及mam家族可调控铁磁性颗粒的形状和大小[39]㊂另有研究发现,磁小体内铁磁性颗粒的形态可能与MTB 的来源有一定的关联㊂例如来自α-蛋白菌和γ-蛋白菌菌属的MTB常产生各向同性生长的八面体棱柱形的铁磁矿,而硝化螺菌菌属的MTB常产生各向异性生长的子弹型铁磁矿[40]㊂4㊀细菌介导生物矿化的应用4.1㊀环境应用随着工业化的快速发展,大量的有毒金属及放射性核素被排放至环境中,对人类健康造成了极大的威胁㊂如何快速有效地回收环境中的污染物是学者们亟需解决的问题㊂随着细菌介导矿化研究的进一步深入,有学者提出可通过耐重金属细菌诱导有毒金属矿化来回收环境中的锶㊁镍㊁铬㊁铅㊁铀㊁镉等有毒金属,改善环境质量[41]㊂虽然高浓度的金属离子可导致多数细菌核酸紊乱及渗透压失衡,但对于这些损伤,细菌已进化出了精妙的抗重金属机制,如金属离子的跨膜运输㊁形成胞内外沉淀㊁与胞内金属硫蛋白的螯合作用等均可将有毒金属离子转化为无毒或毒性较小的物质(图4)[42]㊂由于细菌的大部分抗重金属基因位于质粒上,因此可通过基因操作得到基因编辑细菌,从而用于生物修复[43]㊂例如,研究发现趋磁细菌UPB-MAG05菌株对重金属镉具有高度耐受性,可介导污染水源中镉的矿化沉积,继而在外界磁场的作用下通过磁分离去除,从而净化水质[44]㊂磷酸盐增溶芽孢杆菌可分解含磷酸盐的有机化合物,在其细胞表面产生磷酸盐基团,并与铅离子沉淀为稳定的Pb3(PO4)2,从而达到清除铅离子的目的[45]㊂相较于传统的物理化学修复方法,通过细菌矿化重金属修复污染环境的方法具有成本低廉㊁后期处理简单等优点,但细菌矿化重金属的长期有效性尚未得到证明,已经结合的重金属在环境变化的条件下可能重新活化,回到环境中㊂图4㊀细菌抗多种有毒金属的机制[42]Fig.4㊀The mechanism of bacterial resistance to toxic metals[42]4.2㊀工业应用细菌介导的矿化也可以用于电化学领域的能源存储㊂研究发现铁氧化细菌Acidovorax可介导γ-FeOOH发生矿化,形成保留细菌大小和形状的α-Fe2O3纳米晶体㊂α-Fe2O3纳米晶体组装形成中空多孔的壳,导电性强,在与锂反应时有更强的电化学可逆性㊂此种生成纳米晶体的方法不仅具有生态友好性,也可实现工业上的规模化生产[46]㊂由电化学活性细菌Shewanella oneidensis介导合成的高度分散的钯金合金纳米粒子可用作液体燃料电池的电催化剂[47]㊂研究发现,通过基因技术使大肠杆菌表面表达硅藻silaffin蛋白的重复片段,其调控合成的纳米二氧化钛锐钛矿具有出色的锂储存性能,可用作锂离子电池的阳极[48]㊂混凝土是目前广泛使用的建筑材料,但随着时间的流逝,混凝土内部产生的裂缝会降低建筑结构的机械性能,缩短建筑物使用年限㊂有研究提出可在混凝土中加入能够介导碳酸盐沉淀的细菌,其产生的碳酸钙可增强混凝土对氯离子和渗透水的抵抗力,提高混凝土耐久性439博看网 . All Rights Reserved.㊀第11期王婉蓉等:细菌介导生物矿化的研究进展和强度;同时碳酸钙可填补裂缝,形成自修复混凝土,增加建筑的使用寿命(图5)[49]㊂研究证实,当初始裂缝宽度不大于0.5mm 时,使用自修复混凝土时大部分裂缝可完全愈合[47]㊂但由于混凝土由硅酸盐水泥制成,水化后可产生氢氧化钙,使混凝土呈强碱性,且混凝土基质中的孔隙尺寸小于1μm,而细菌的大小为1~4μm,这些条件都不利于细菌存活[50]㊂因此如何提高细菌在混凝土基质中的生存能力是目前的研究热点㊂有学者提出可使用微胶囊技术来保护细菌,使细菌在合适的环境下介导碳酸盐沉淀[51]㊂图5㊀通过细菌诱导碳酸钙沉淀修复混凝土开裂的示意图[49]Fig.5㊀Schematic of bacteria induced calcium carbonate precipitation to repair concrete cracking [49]4.3㊀生物医学应用4.3.1㊀医疗成像设备和诊断磁共振成像(magnetic resonance imaging,MRI)技术由于具有良好的空间分辨率和软组织对比度,是临床上常用的影像检查手段之一㊂研究发现MTB 产生的磁性纳米颗粒具有较强磁性,可作为造影剂增强组织中质子共振吸收,使局部组织图像得到增强,从而提高检查的灵敏度和特异性[52]㊂除增强成像对比度之外,功能化的磁性纳米颗粒芯片还可用于食源性病原物的检测,如大肠杆菌㊁霍乱弧菌㊁空肠弯曲菌㊁金黄色葡萄球菌等[53]㊂如图6所示,趋磁细菌MO-1功能化之后可与金黄色葡萄球菌表面的A 蛋白结合,从而实现靶向功能[54]㊂目前可以通过化学修饰和基因工程的方法生产功能化磁小体㊂化学修饰作用于磁小体中的Mam㊁Mms 等蛋白上,有以下结合方式:①通过磁小体膜上的氨基或羧基进行功能化修饰,例如经肽P75修饰的磁小体可与人表皮生长因子受体和上皮生长因子受体2结合[55];②使用葡萄球菌蛋白A 用作融合标签,葡萄球菌蛋白A 作为一种免疫球蛋白G 结合蛋白,可与MamC㊁MamF 以及免疫球蛋白Fc 区结合,从而介导磁小体-葡萄球菌蛋白A 复合物与抗体结合[56];③利用磁小体膜上的 NH 2基团与抗体的 NH 2或 SH 基团之间的反应进行化学修饰;④用生物素/链霉亲和素进行修饰;⑤利用正负电荷之间的相互作用进行修饰,磁小体膜上的磷脂带有负电荷,可与带正电荷的抗癌重组质粒热激蛋白㊁70-polo 样激酶1短发夹RNA 以及阿霉素结合[57]㊂另外还可通过基因工程改造对磁小体进行功能化修图6㊀趋磁细菌靶向金黄色葡萄球菌的微机器人系统的构建[54]Fig.6㊀Construction of a microrobot system using magnetotactic bacteria for targeting Staphylococcus aureus [54]539博看网 . All Rights Reserved.中国材料进展第40卷饰㊂将表达功能蛋白的基因与mms16,mam13等膜蛋白基因融合,再将融合基因转移到MTB中,从而可实现目标蛋白的表达㊂例如,将磁小体和翡翠绿色荧光蛋白(EmGFP)或生物素修饰的烟草花叶病毒(tobacco mosaic virus,TMV)共同培养,可生成表达这些蛋白的磁性纳米链[58]㊂由于化学修饰可能引入有毒物质,且在MTB中引入外来活性蛋白质的基因的操作比较复杂,因此最近的研究中提出了一种新的修饰方法㊂首先通过基因技术在大肠肝菌中表达与磁小体MamC蛋白融合的抗人表皮生长因子受体2(human epidermal growth factor receptor-2, HER2),然后去除磁小体膜中的磷脂双层中的膜蛋白,以利于从大肠肝菌中提取的基因工程产物抗HER2与磁小体上的MamC蛋白结合,从而实现HER2阳性乳腺癌在磁共振成像中的检测[59]㊂这种技术有望成为无创检测肿瘤的手段,具有较大的临床应用价值㊂4.3.2㊀抗肿瘤方法高温疗法可通过多种机制作用于癌细胞上使其变性坏死,但目前该疗法缺乏特异性,难以区分健康细胞与癌细胞㊂遂有研究提出 生物靶向磁性热疗 的概念,意为在外源交变磁场的作用下加热磁性颗粒,由于磁滞损耗或松弛损耗产生不同程度的升温现象,可在磁性颗粒聚集的地方选择性地抑制癌细胞增殖[60]㊂由MTB产生的磁小体由于磁性较强,可在交变磁场中产生较大的热量;同时由于磁小体呈链状排列,不易聚集,可使肿瘤细胞均匀升温,有效抑制其增殖[61],因此磁小体在磁热疗领域有较大的应用前景㊂研究表明,聚赖氨酸包裹的磁小体具有更好的生物相容性,在胶质母细胞瘤小鼠模型的实验性磁热疗中,可显著抑制肿瘤细胞的生长[6]㊂但是到目前为止,多数关于磁小体抗肿瘤治疗的研究都是使用肿瘤细胞株进行实验的,未进行动物实验研究或人类临床试验,因此磁小体的临床抗肿瘤能力还需进一步验证㊂4.3.3㊀药物输送系统靶向给药是指将药物选择性地传输定位于病变位置,从而发挥药理作用的给药方式㊂在肿瘤微环境中,由于细胞的大量增殖消耗氧气,肿瘤组织周围氧气缺乏㊂目前使用的纳米药物载体,如脂质体㊁胶束㊁聚合物纳米颗粒难以到达缺氧区域,靶向率低㊂而MTB适合厌氧生长,故目前有研究通过MTB和磁小体构建纳米机器人,在外磁场的作用下,纳米机器人可聚集于病变部位,提高病变部位的药物浓度,改善治疗效果[62]㊂例如,将载有药物的纳米脂质体交联至海洋趋磁细菌MC-1表面,并将其注射到实验小鼠的肿瘤组织周围,在外磁场的作用下,有高达55%的MC-1细胞渗透到肿瘤缺氧区[63]㊂5㊀结㊀语综上所述,相比于物理和化学合成方法,细菌介导生成的矿物在环境㊁工业及生物医学领域均发挥着重要的作用㊂虽然目前对细菌介导的生物矿化的研究已经取得部分进展,但仍有许多关键的科学问题亟待解决㊂由于多数细菌介导矿物生成的实验室培养条件并不适宜工业化生产,所以如何将实验室阶段的科学成果转化为可规模化生产的具体技术是限制其应用的关键瓶颈㊂其次,虽然纳米机器人在肿瘤治疗领域有较大的应用前景,但人体免疫系统对其会有如何反应目前尚不完全清楚[64]㊂为了实现细菌介导生物矿化的大规模应用,还需进一步地研究以解决上述问题㊂参考文献㊀References[1]㊀ALSENZ H,ILLNER P,ASHCKENAZI-POLIVODA S,et al.Geo-chemical Transactions[J],2015,16(1):2.[2]㊀DHAMI N K,REDDY M S,MUKHERJEE A.Frontiers in Microbiolo-gy[J],2014,5:304.[3]㊀PERRY R S,MCLOUGHLIN N,LYNNE B Y,et al.Sedimentary Ge-ology[J],2007,201(1/2):157-179.[4]㊀PETERS S E,GAINES R R.Nature[J],2012,484(7394):363-366.[5]㊀SCHWADERER A L,WOLFE A J.Annals of Translational Medicine[J],2017,5(2):32-37.[6]㊀LE FÈVRE R,DURAND-DUBIEF M,CHEBBI I,et al.Theranostics[J],2017,7(18):4618-4631.[7]㊀LOHßE A,KOLINKO I,RASCHDORF O,et al.Applied and Envi-ronmental Microbiology[J],2016,82(10):3032-3041. [8]㊀AL DISI Z A,JAOUA S,BONTOGNALI T R,et al.Frontiers in En-vironmental Science[J],2017,5:1.[9]㊀BENTOV S,ABEHSERA S,SAGI A.The Mineralized Exoskeletons ofCrustaceans[M]//COHEN E,MOUSSIAN B.Extracellular Composite Matrices in Arthropods.Cham:Springer International Publishing, 2016:137-163.[10]VITTORI M,ŽNIDARŠI N,ŽAGAR K,et al.Journal of Structural Biology[J],2012,180(1):216-225.[11]URIZ M J,AGELL G,BLANQUER A,et al.Evolution[J],2012,66(10):2993-2999.[12]MYKYTCZUK N,LAWRENCE J R,OMELON C R,et al.Polar Biol-ogy[J],2016,39(4):701-712.[13]SAURO F,CAPPELLETTI M,GHEZZI D,et al.Scientific Reports[J],2018,8(1):17569.[14]KREMER B,KAZMIERCZAK J,LUKOMSKA-KOWALCZYK M,etal.Astrobiology[J],2012,12(6):535-548.[15]CHEN Y R,ZHANG W Y,ZHOU K,et al.Environmental Microbiol-ogy Reports[J],2016,8(2):218-226.639博看网 . All Rights Reserved.。

a r X i v :h e p -l a t /0409150v 1 27 S e p 20043-d lattice SU(3)free energy to four loops∗MIT-CTP-3541;UPRF-2004-18F.Di Renzo a ,A.Mantovi a ,V.Miccio a ,Y.Schroder b ,C.Torrero a aDipartimento di Fisica,Universit`a degli Studi di Parma,and INFN,Gruppo Collegato di Parma,ItaliabCenter for Theoretical Physics,MIT,Cambridge,MA,USAWe report on the perturbative computation of the 3d lattice Yang-Mills free energy to four loops by means of Numerical Stochastic Perturbation Theory.The known first and second orders have been correctly reproduced;the third and fourth order coefficients are new results and the known logarithmic IR divergence in the fourth order has been correctly identified.Progress is being made in switching to the gluon mass IR regularization and the related inclusion of the Faddeev-Popov determinant.1.IntroductionThe main goal of finite temperature QCD is to characterize the deconfinement transition bet-ween the low temperature regime,ruled by con-finement,and the high temperature regime ruled by asymptotic freedom.In this respect the free energy density,i.e.the pressure ,is a sort of ‘theoretical laboratory’in which to study such a transition,and,eventually,a potential candidate observable in heavy ion collisions.Evidently,the large T limit of the pressure is that of an ideal gas of non-interacting particles,p ∝T 4;unfortu-nately,lattice simulations across the whole tem-perature range are not feasible and our efforts and understanding are confined to the opposite ends of the temperature range:namely,the low temperature regime (up to some 4÷5times the transition temperature T c ∼200MeV)which is accessible to actual computational resources,and the high temperature regime at which the pres-sure exhibits a purely perturbative behaviour.Dimensional reduction [1]has been applied [2]to fill the gap:4d QCD is matched to 3d SU (3)Yang-Mills (YM)coupled to a Higgs field in the adjoint representation;such a theory can then be matched to 3d SU (3)YM,which captures the ultrasoft degrees of freedom;both these reduc-tions have been successfully performed in the∗Presentedby Andrea Mantovischeme.Finally,3d YM has to be treated non-perturbatively,the only effective means being the lattice.Indeed lattice computations can be con-sistently incorporated into the dimensional reduc-tion strategy:the theory is superrenormalizable and all divergences can be computed perturba-tively;this allows a clean matching of the schemes in the continuum.It is well known that comput-ing at high orders in LPT is quite hard a task;in this respect the approach of Numerical Stochastic Perturbation Theory (NSPT)[3]is a very efficient one.Let f ≡−V ln Z be the free energy associated with the Wilson action S W =β0 P (1−ΠP ),β0=2N c /(a 4−d g 20)being the dimensionless bare lattice inverse coupling in d dimensions.To com-pute the free energy one can revert to the com-putation of the plaquette,being1−ΠP =2a d∂β01β0+c 2(N c ,d )β30+c 4(N c ,d )616g 2(3)12−a−1c3648g60+O(a).so that thefirst four coefficients uniquely deter-mine the matching to the continuum;c1and c2 being long known,c3and c4were the aims of the computation.The presence has already been established[4]of a logarithmic IR divergence at fourth loop order;it was our aim to recover the scheme independent coefficient of such a loga-rithm:the tilde on c4reminds us that the IR divergence has to be isolated and subtracted by means of a definite IR regulator,which we choose to be the finite lattice size L inherent to any lat-tice simulation.putational setupWe have inserted the expansion Uµ(n)=1+ 8i=1β−i3subtracted c4.4.PerspectivesA definite IR regulator enables one to isolate afinite part out of the4loops contribution to the plaquette;we have been employing the finite volume inherent to any computer simulation.A mass is a commonly used regulator in continuum computations;the coupling itself(dimensionful in 3d YM)is quite a natural IR regulator for non-perturbative lattice simulations.Despite the fact that the coefficient of the logarithmic divergence is universal it is clear that definite coefficients re-late different regularizations.We are interested in the perturbative matching between the lattice and a continuum perturbative scheme:in both approaches the same gluon mass IR regulator can be employed so that the same mismatch shows up with respect to data coming from nonpertur-bative computer simulations with the coupling as IR regulator.Employing massive gluons is the na-tural extension of our computational programme. Inserting a mass into the gluon propagator amounts to switching to the Lie algebra for the definition of the new lattice action and this we perform at a definite step of the computation.It is well known that the Lie algebra YM action is made out of a gaugefixing term and the ghost action resulting from the FP determinant.Our NSPT strategy entails the construction of the Eu-ler scheme solution U′=exp(−ǫF)U to Eq.(4); the quantity F belongs to the Lie algebra and our algorithm entails going back and forth from the group to the algebra:at that stage we include the new contribution to the action.The strategy for a determinant is well established[6,7]and is employed by the Parma group in the unquenched NSPT approach to lattice QCD[8];the determi-nant is simulated without introducing fermion or ghostfields and the inversions of the nonlocal ma-trix is performed perturbatively via an efficient FFT by a back and forth procedure from Fourier space:the zeroth order of any propagator is di-agonal in momentum space and the construction of successive orders does not require any matrix inversion.The implementation of such a strategy is in progress;signals of the stabilization of gauge dependent quantities as well as of the invariance of gauge invariant quantities make us confident about the reliability of the whole procedure. REFERENCES1. E.Braaten and A.Nieto,Phys.Rev.D53,3421(1996);2.K.Kajantie,ine,K.Rummukainen andY.Schroder,Phys.Rev.Lett.86,10(2001);3. F.Di Renzo,E.Onofri,G.Marchesini andP.Marenzoni,Four loop result in SU(3)lat-tice gauge theory by a stochastic method:lat-tice correction to the condensate,Nucl.Phys.B426(1994)675,[hep-lat9405019].4.K.Kajantie,ine,K.Rummukainen andY.Schroder,Phys.Rev.sss D67,105008 (2003);5. F.Di Renzo, A.Mantovi,V.Miccio andY.Schroder,J.High Energy Phys.05(2004) 006;6.G.G.Batrouni,G.R.Katz,A.S.Kronfeld,G.P.Lepage,B.Svetitski and K.G.Wilson,Phys.Rev.D32(1985)2736.7.G.Burgio,F.Di Renzo,G.Marchesini,E.Onofri,M.Pepe,L.Scorzato,Nucl.Phys.B (Proc.Suppl.)73(1999)853.8. F.Di Renzo,L.Scorzato,Nucl.Phys.B(Proc.Suppl.)94(2001)567.。

南京林业大学艺术设计学院 汤箬梅 李俊杰*引言自闭症是一种发育障碍性疾病，研究表明，儿童自闭症发病率占我国各类精神疾病首位，并且已成为当今最普遍的发展性障碍疾病之一，我国自闭症儿童超200万，而且这种趋势仍在上升。

患儿常会出现行为异常，心理障碍，缺少社会交往能力等症状。

随着自闭症康复医疗水平的进步，科学、舒适的康复空间设计能够对患儿的感官系统、心理生理健康、情感发展、社会交流的治疗起着积极作用，提升患儿的康复效果。

但目前我国多数儿童康复空间的设计仍停留在鲜艳的色彩和图案上，功能简单、造型单一，并未充分考虑自闭症儿童的实际需求。

感官统合理论是通过大脑感知环境，进而刺激感官系统的过程，这一过程对患儿的康复会起到积极作用。

本研究依据感官统合理论及自闭症儿童的心理生理特征，探索自闭症儿童康复空间新的设计模式，提升空间的整体康复效果。

一、感官统合理论基本原理感觉统合理论是由美国心理学博士爱尔丝于1969年系统提出的。

其原理是大脑和身体相互协调运作的学习过程，感觉统合是人体将不同的感觉通路（听觉、味觉、嗅觉、触觉、视觉、前庭觉和本体觉等）从环境中获取的感觉信息组合起来输入大脑，大脑对获取信息进行加工处理，处理过程包括筛选、解释、比较、抑制、联系、统一等，进而做出适应性反应的能力，简称“感统”。

感官统合的发展会影响儿童的身体健康、日常行为表现、儿童情绪智力等，儿童的各项发展都是以感官统合为基础的，若儿童的感官统合能力存在障碍，会导致儿童无法融入集体，给儿童生理和心理健康造成影响。

研究表明，基于感官统合理论下的环境设计会对儿童的感官系统产生积极的影响，能够促使大脑产生或抑制神经化学物质的分泌，可以帮助患者感官统合能力的发展，从而促进患者康复，如图1[1]。

摘要：旨在运用感官统合理论介入自闭症儿童康复空间设计，根据儿童的感官体验，营造出易于自闭症儿童康复的空间环境。

文章从自闭症儿童的内在特征出发，通过介入感官统合理论，构建情节丰富的游戏场所，营造亲近自然的景观环境，创造寓教于乐的教育空间，搭建安全舒心的康复场地等设计策略刺激儿童的感官系统，提出有利于自闭症儿童康复的空间模式。

Fa-Yueh Wu—Curriculum vitaeFa-Yueh Wu was born January1932in China.He moved to Taiwan in1949where he received a B.S.degree in Electrical Engineering from the Chinese Naval College of Technology in1954and,after serving the Navy for three years from1954to1957, a M.S.degree in physics from the National Tsing Hua University in1959.The same year,he entered Washington University in St.Louis as a physics graduate student, where he studied under the late Eugene Feenberg,working on many-body theory, a topic to which he has continued to make important contributions throughout the years. After obtaining his Ph.D.in physics in1963,he continued at Washington University as a postdoc for9months and was appointed an Assistant Professor at the Virginia Polytechnic Institute in the same year.In1967he moved to Northeastern University in Boston where he has remained until the present.Promoted to Professor in1976,he was named a University Distinguished Professor in1989and the Matthews University Distinguished Professor of Physics in1992.Professor Wu’s works in many-body theory,particularly those related to the the-ory of liquid He4and He3and the formulation of the correlated-basis wave function approach,have been in uential for years.In the late1960s,he began working in sta-tistical mechanics with a special interest in exact solutions of lattice models of phase transitions and critical phenomena.He has over200papers published in refereed scien-tiÿc journals and has authored a number of important review articles and monographs. Professor Wu’s1982review on the Potts model is a classic which has over the years drawn over1000citations.Another classic among his works is his1968joint paper with E.H.Lieb on the exact solution of the ground state of the one-dimensional Hub-bard model,a fundamental paper on strongly correlated electron systems which has drawn over1400citations.A full account of the Lieb–Wu solution is now published for theÿrst time in this Proceedings,possibly establishing a record34years time span between the publication of a Letter and the full report of a seminal research. Professor Wu has solved numerous lattice models of phase transitions.These in-clude lattice models in three dimensions and dimer models having di erent geometry and topology.He has also contributed signiÿcantly to the study of the role played by integrable models in the mathematical theory of knots and knot invariants and has written a comprehensive review on the subject.Likewise,he has made deÿnitive con-tributions in graph theory and combinatorics which clarify and elucidate the interplay of combinatorics in statistical physics.A Fellow of the American Physical Society since1972,Professor Wu served as the Program Director for the Condensed Matter Theory Program at the National Science Foundation from1983to1984.In this capacity he helped maintain the quality and viability of the Program at a time of declining funding growth.Within the scientiÿc community he has served as the editor of several physics journals,given many invited talks and organized a number of international conferences.doi:10.1016/S0378-4371(02)01801-0xvi Curriculum vitaeProfessor Wu has visited numerous universities and institutions worldwide.He was a1973Fulbright–Hays Senior Research Scholar.He has been a Visiting Professor at the Australian National University(1973,1990,1995),the University of Amsterdam (1994),the Institute-Lorentz(1980),the University of Delft(1980),the Institute of Nuclear Energy(KFA)at J u lich(1981),the University of Paris VI(1991,1996),the National Taiwan University(1984),the National Tsing Hua University(1974,1988, 1999),the Brazilian Center of Theoretical Physics(1985),the Institute of Physics of Academia Sinica,Beijing(1979),the Institute of Physics of Academia Sinica,Taipei (1990),the University of Washington(1987),and theÃEcole Polytechnique FÃe derale of Lausanne(1975,1978,1985,1988,1991).He has also been the Invited Distinguished Chair Professor of the National Science Council,Taipei(1991).He is a Guest Professor at Nankai University in Tianjin,and an Honorary Professor at the Southwest University in Chongqing and at Beijing Normal University.He is named the Outstanding Alumnus of the National Tsing Hua University in2003.Selected Publications of Fa Yueh Wu—Papers with9or more citations based on database of Science Citation Index Expanded(ISI Web of Science)in early November 2002.[1]E.Lieb,F.Y.Wu,Absence of Mott transition in an exact solution of the short-rangeone-band model in one dimension,Phys.Rev.Lett.20(1968)1445–1448,1422 citations.[2]F.Y.Wu,The Potts model,Rev.Mod.Phys.54(1982)235–268,1096citations.[3]C.Fan,F.Y.Wu,General lattice model of phase transitions,Phys.Rev.B2(1970)723–733,222citations.[4]R.J.Baxter,F.Y.Wu,Exact solution of an Ising model with three-spin interactionson a triangular lattice,Phys.Rev.Lett.31(1973)1294–1297,161citations. [5]F.Y.Wu,Ising model with four-spin interactions,Phys.Rev.B4(1971)2312–2314,135citations.[6]R.J.Baxter,S.B.Kelland,F.Y.Wu,Equivalence of the Potts model or Whit-ney polynomial with the ice-type model:a new derivation,J.Phys.A9(1976) 397–406,123citations.[7]C.Fan,F.Y.Wu,Ising model with next-neighbor interactions:some exact resultsand an approximate solution,Phys.Rev.179(1969)560–570,112citations. [8]F.Y.Wu,E.Feenberg,Theory of Fermi liquids,Phys.Rev.128(1962)943–955,106citations.[9]R.J.Baxter,F.Y.Wu,Ising model on a triangular lattice with three-spin in-teractions:I.The eigenvalue equations,Aust.J.Phys.27(1974)357–367,92 citations.[10]F.Y.Wu,Y.K.Wang,Duality transformation in a many component spin model,J.Math.Phys.17(1976)439–440,88citations.[11]F.Y.Wu,Percolation and the Potts model,J.Stat.Phys.18(1978)115–123,63citations.[12]A.Hinterman,H.Kunz,F.Y.Wu,Exact results for the Potts model in two di-mensions,J.Stat.Phys.19(1978)623–632,63citations.Curriculum vitae xvii [13]F.Y.Wu,K.Y.Lin,Two phase transitions in the Ashkin–Teller model,J.Phys.C7(1974)L181–L184,60citations.[14]F.Y.Wu,E.Feenberg,Ground state of liquid helium(Mass4),Phys.Rev.122(1961)739–742,57citations.[15]F.Y.Wu,Remarks on the modiÿed KDP model,Phys.Rev.168(1968)539–543,52citations.[16]D.H.Lee,R.G.Ca ish,J.D.Joannopoulos,F.Y.Wu,Antiferromagnetic classicalXY-model:a mean-ÿeld analysis,Phys.Rev.B29(1984)2680–2684, 44citations.[17]F.Y.Wu,Exactly soluble model of ferroelectric phase transition in two dimen-sions,Phys.Rev.Lett.18(1967)605–607,43citations.[18]F.Y.Wu,Potts model of ferromagnetism,J.Appl.Phys.55(1984)2421–2425,39citations.[19]F.Y.Wu,Knot theory and statistical mechanics,Rev.Mod.Phys.64(1992)1099–1131,39citations.[20]C.N.Chen,C.K.Hu,F.Y.Wu,Partition function zeroes of the square lattice Pottsmodel,Phys.Rev.Lett.76(1996)169–172,37citations.[21]G.Keiser,F.Y.Wu,Electron gas at metallic densities,Phys.Rev.A6(1972)2369–1377,33citations.[22]F.Y.Wu,On the Horiguchi’s solution of the Blume–Emery–Gri ths model,Phys.Lett.A116(1986)245–247,33citations.[23]F.Y.Wu,Eight-vertex model on the honeycomb lattice,J.Math.Phys.6(1974)687–691,32citations.[24]Y.K.Wang,F.Y.Wu,Multi-component spin model on the Cayley tree,J.Phys.A9(1976)593–604,31citations.[25]F.Y.Wu,M.K.Chien,Convolution approximation for the n-particle distributionfunction,J.Math.Phys.11(1970)1912–1916,30citations.[26]I.G.Enting,F.Y.Wu,Triangular lattice Potts model,J.Stat.Phys.28(1982)351–378,30citations.[27]K.Y.Lin,F.Y.Wu,Phase diagram of the antiferromagnetic triangular Ising modelwith anisotropic interactions,Z.Phys.B33(1979)181–185,29citations. [28]F.Y.Wu,Critical point of planar Potts models,J.Phys.C12(1979)645–649,28citations.[29]F.Y.Wu,Exact solution of a model of an antiferroelectric transition,Phys.Rev.183(1969)604–607,27citations.[30]C.S.Hsue,K.Y.Lin,F.Y.Wu,Staggered eight-vertex model,Phys.Rev.B12(1975)429–437,27citations.[31]F.Y.Wu,K.Y.Lin,Staggered ice-rule model—the Pfa an solution,Phys.Rev.B12(1975)419–428,25citations.[32]H.Kunz,F.Y.Wu,Site percolation as a Potts model,J.Phys.C11(1978)L1–L4,25citations.[33]F.Y.Wu,Cluster development in an N-body problem,J.Math.Phys.4(1963)1438–1443,24citations.[34]J.E.Sacco,F.Y.Wu,Thirty-two vertex model on a triangular lattice,J.Phys.A8(1975)1780–1787,24citations.[35]X.N.Wu,F.Y.Wu,The Blume–Emery–Gri ths model on the honeycomb lattice,J.Stat.Phys.50(1988)41–55,24citations.xviii Curriculum vitae[36]F.Y.Wu,G.Rollet,H.Y.Huang,J.-M.Maillard,C.K.Hu,C.N.Chen,Directedcompact lattice animals,restricted partitions of numbers,and the inÿnite-state Potts model,Phys.Rev.Lett.76(1996)173–176,24citations.[37]J.H.H.Perk,F.Y.Wu,Non-intersecting string model and graphical approach:equivalence with a Potts model,J.Stat.Phys.42(1986)727–742,22 citations.[38]F.Y.Wu,X.N.Wu,H.W.J.Bl o te,Critical frontier of the antiferromagnetic Isingmodel in a nonzero magneticÿeld:the honeycomb lattice,Phys.Rev.Lett.62 (1989)2273–2276,22citations.[39]F.Y.Wu,Exact results for a dilute Potts model,J.Stat.Phys.23(1980)773–782,21citations.[40]H.K.Sim,R.Tao,F.Y.Wu,Ground-state energy of charged quantum liquids intwo dimensions,Phys.Rev.B34(1986)7123–7128,21citations.[41]W.Kinzel,W.Selke,F.Y.Wu,A Potts model with inÿnitely degenerate groundstate,J.Phys.A14(1981)L399–L404,19citations.[42]G.O.Zimmerman,A.K.Ibrahim,F.Y.Wu,A planar classical dipolar system ona honeycomb lattice,Phys.Rev.B37(1988)2059–2065,19citations.[43]Y.Chow,F.Y.Wu,Residual entropy and validity of the third law of thermody-namics in discrete spin systems,Phys.Rev.B36(1987)285–288,18citations.[44]F.Y.Wu,Multiple density correlations in a many particle system,J.Math.Phys.12(1971)1923–1929,17citations.[45]F.Y.Wu,Ashkin–Teller model as a vertex problem,J.Math.Phys.18(1977)611–613,17citations.[46]R.K.P.Zia,F.Y.Wu,Critical point of the triangular Potts model with two-andthree-site interactions,J.Phys.A14(1981)721–727,17citations.[47]F.Y.Wu,Dilute Potts model,duality and site-bond percolation,J.Phys.A14(1981)L39–L44,17citations.[48]X.N.Wu,F.Y.Wu,Exact results for lattice models with pair and triplet interac-tions,J.Phys.A22(1989)L1031–L1035,17citations.[49]F.Y.Wu,Exact results on a general lattice statistical model,Solid State Commun.10(1972)115–117,16citations.[50]F.Y.Wu,H.E.Stanley,Domany–Kinzel model of directed percolation:formula-tion as a random-walk problem and some exact results,Phys.Rev.Lett.48(1982) 775–777,16citations.[51]J.H.H.Perk,F.Y.Wu,Graphical approach to the non-intersecting string model:star-triangle equation,inversion relation and exact solution,Physica A138(1986) 100–124,16citations.[52]F.Y.Wu,K.Y.Lin,Ising model on the Union Jack lattice as a free-Fermionmodel,J.Phys.A20(1987)5737–5740,16citations.[53]X.N.Wu,F.Y.Wu,Duality properties of a general vertex model,J.Phys.A22(1989)L55–L60,16citations.[54]F.Y.Wu,Critical behavior of two-dimensional hydrogen-bonded antiferroelectrics,Phys.Rev.Lett.22(1967)1174–1176,14citations.[55]F.Y.Wu,Number of spanning trees on a lattice,J.Phys.A10(1977)L113–L115,14citations.[56]J.R.Banavar,F.Y.Wu,Antiferromagnetic Potts model with competing interac-tions,Phys.Rev.B29(1984)1511–1513,13citations.Curriculum vitae xix [57]F.Y.Wu,Exact solution of a triangular Ising model in a nonzero magneticÿeld,J.Stat.Phys.40(1985)613–620,12citations.[58]F.Y.Wu,Spontaneous magnetization of the three-spin Ising model on the UnionJack lattice,J.Phys.C8(1975)2262–2266,11citations.[59]F.Y.Wu,Solution of an Ising model with two-and four-spin interactions,Phys.Lett.A38(1972)77–78,11citations.[60]F.Y.Wu,Two-dimensional Ising model with crossing and four-spin interactionsand a magneticÿeld i kT=2,J.Stat.Phys.44(1986)455–463,11citations. [61]F.Y.Wu,H.T.Tan,E.Feenberg,Necessary conditions on radial distributionsfunctions,J.Math.Phys.8(1967)864–869,10citations.[62]F.Y.Wu,Critical behavior of hydrogen-bonded ferroelectrics,Phys.Rev.Lett.24(1970)1476–1478,10citations.[63]K.G.Chen,H.H.Chen,C.S.Hsue,F.Y.Wu,Planar classical Heisenberg modelwith biquadratic interactions,Physica A87(1977)629–632,10citations. [64]F.Y.Wu,Phase diagram of a spin-one Ising system,Chin.J.Phys.16(1978)153–156,10citations.[65]S.Sarbach,F.Y.Wu,Exact results on the random Potts model,Z.Phys.B44(1981)309–316,10citations.[66]F.Y.Wu,Eight-vertex model and Ising model in a nonzero magneticÿeld on thehoneycomb lattice,J.Phys.A23(1990)375–378,10citations.[67]C.K.Hu,C.N.Chen,F.Y.Wu,Histogram Monte-Carlo renormalization group:applications to the site percolation,J.Stat.Phys.82(1996)1199–1206, 10citations.[68]W.T.Lu,F.Y.Wu,Dimer statistics on a M o bius strip and the Klein bottle,Phys.Lett.A259(1999)108–114,10citations.[69]H.J.Brascamp,H.Kunz,F.Y.Wu,Some rigorous results for the vertex model instatistical mechanics,J.Math.Phys.14(1973)1927–1932,9citations. [70]X.N.Wu,F.Y.Wu,Critical line of the square-lattice Ising model,Phys.Lett.A144(1990)123–126,9citations.[71]L.H.Gwa,F.Y.Wu,Critical surface of the Blume–Emery–Gri ths model on thehoneycomb lattice,Phys.Rev.B43(1991)13755–13777,9citations.[72]F.Y.Wu,H.Y.Huang,Exact solution of a vertex model in d dimensions,Lett.Math.Phys.29(1993)205–213,9citations.[73]H.Y.Huang,F.Y.Wu,H.Kunz,D.Kim,Interacting dimers on the honeycomblattice:an exact solution of theÿve-vertex model,Physica A228(1996)1–32, 9citations.[74]F.Y.Wu,Duality relations for Potts correlation functions,Phys.Lett.A228(1997)43–47,9citations.[75]R.Shrock,F.Y.Wu,Spanning trees on graphs and lattices in d dimensions,J.Phys.A33(2000)3881–3902,9citations.[76]W.J.Tzeng,F.Y.Wu,Spanning trees on hypercubic lattices and non-orientablesurfaces,Appl.Math.Lett.13(2000)19–25,9citations.。

当前LatticeQCD的国内外研究现状Z 4430 Belle 在道发现一个共振结构如果实验上确认其存在，则最小的夸克组分应该是其质量与和的阈十分接近量子数还没有确定。

一些理论家把它解释为可能的 S-wave分子态或者四夸克态候选者。

对此，我们进行了两方面的研究：计算的散射；用四夸克场算符计算可能的质量谱，用单粒子态和两粒子态有限个点上对体积的依赖关系来判断所得到的态是散射态还是束缚态。

这两方面的都得到了一些初步结果。

散射根据Luscher公式，在有限的格点上，两粒子散射系统的能量、两粒子自由能量以及低能散射的散射长度之间有如下关系散射能量两粒子自由能量散射长度约化质量空间体积 a 0.204fm 400confs. a0.144fm 400confs. Beta 2.5的结果 Beta 2.8的结果表示 A1 A2 B1 B2 E 2.5 0.370 33 0.494 60 0.397 64 0.432 63 0.267 33 2.8 0.624 56 0.507 76 0.523 77 0.517 78 0.667 60 手征外推后散射长度（单位：fm 的结果：初步结论：在所有的情况下，的S-wave散射的散射长度为正，说明之间的相互作用是吸引性的。

至于这种吸引性的相互作用的强弱、以及能否构成束缚态，还需要进一步的理论分析。

小结：井冈山长征抗战战略防御战略相持战略进攻解放战争建国萌芽生存成长成功 2.我们的方针制胜三大法宝：群众路线：CLQCD努力工作，合作攻关。

理论联系实际：密切结合BES试验，关注国际实验新结果。

统一战线：希望大家多多支持，多多建议。

1.我们所处的阶段谢谢！基态是单粒子态还是两粒子态？可能的判据：Weight的体积效应。

单粒子态：两粒子态：当前Lattice QCD的国内外研究现状陈莹中国科学院高能物理研究所报告内容一、Lattice QCD简介二、国际研究现状三、国内研究现状四、关于X 3872 和Z 4430 五、小结一、Lattice QCD 简介 Wick 转动Euclidean 空间QCD作用量路径积分时空离散化连续时空四维超立方格点体系无限自由度有限自由度路径积分量子化生成泛函: 物理观测量: 算符的真空平均值淬火近似 quenched approximation : 物理含义: 不考虑夸克真空极化图,即忽略海夸克效应 Monte Carlo 模拟重点抽样：根据Boltzmann 分布产生由有限数量的位形构成的统计系综，计算可观测量的系综平均值，样本越大，统计误差越小。

2022-2023学年四川省成都市蓉城高中联盟高二下学期期中考试英语试题1. Mardi Gras 2021 was a very quiet, socially distanced event. And festivities were still a bits ubdued in 2022, at least by pre-pandemic standards. City officials and experienced tourists have some Mardi Gras guidance:*Don’t ignore parking rules during Mardi Gras weekend. Click here to find out some transportation options. Follow the parking rules or risked being towed and paying fines of “Biblical proportions, ” according to MardiGras New Orleans. com.*Don’t move other people’s stuff on the parade rou te. It’s bad form to move unoccupied chairs. Just scout around for an empty spot.*Don’t reach down to pick up beads and other throws. In the excitement, you could end up with your hand stamped or worse. Instead, put your foot on the item and hold it ther e until it’s safe to bend over and get it.*Don’t relieve yourself on the street. The good folks of New Orleans even have this handy bathroom guide. Make it your “Number I” priority.If you’re thinking about planning a future trip around the festivities,get an early start. Don’t wait until January to plan your visit. Things book up fast, starting as early as August: you’re leaving it more to luck the longer you wait. So if you’ve missed the boat for this year, remember that for 2024, when Mardi Gras falls on February 13.1. According to the guidance, what should people do during Mardi Gras?A．Move unoccupied chairs freely.B．Pay little attention to transportation options.C．Put the handy bathroom guide in the first place.D．Pick up the item from the road as soon as possible.2. When do the things start to be booked?A．In January. B．In February.C．In August. D．In December.3. Where does the passage most likely come from?A．A website. B．A textbook.C．A magazine. D．A newspaper.2. “My journey start ed on a boat. I spent a year in a refugee camp. And somehow, I ended up here on Hollywood’s biggest stage.” Ke Huy Quan said after winning an Academy Award for best actor in a supporting role for his portrayal(演绎) of the unfortunate yet heroic Waymond Wang.“They say stories like this only happen in the movies. I cannot believe it’s happening to me. This is the American dream.” But Quan has acknowledged the difficulties in his journey, too, and how he almost gave up his dreams when opportunities dried up.Quan was born in Saigon and came to Los Angeles in 1979 after fleeing Vietnam and living in Hong Kong as a refugee after the war ended. He began his Hollywood career as a beloved child actor in “Indiana Jones and the Temple of Doom” and “The Goonies.” He kept on auditioning(试镜) after that, but his phone stopped ringing.Quan reimagined his career path, going on to study film at the University of Southern California and to work behind the scenes as a stunt coordinator(武术指导) and assistant director. He wouldn’t have another film role for nearly 20 years.Seeing the Asian ca st of the 2018 movie “Crazy Rich Asians” made him realize how much he missed acting. And as soon as he came across the “Everything Everywhere” script, he knew he was the right person to play Waymond.His big-screen comeback has earned him good reviews and numerous accolades, including Golden Globe, Critics Choice and SAG awards for best supporting actor. And Quan, 51, says these days he’s feeling more optimistic about the Hollywood prospects for him and other Asian actors.1. What can be inferred from Quan’s words in Paragraph 2?A．He gave up his American dreams.B．He loved watching movies very much.C．It’s difficult for him to read stories in America.D．It’s hard for him to win an Academy Award for best actor.2. What does the underlined word “accolades” probably mean in last paragraph?A．Decisions. B．Prizes.C．Comments. D．Opinions.3. What can we learn about Quan from this passage?A．Quan’s career path was flat.B．Quan had a happy childhood.C．Quan hesitated to play Waymond after reading script.D．Quan has a positive attitude to the Hollywood prospects recently.4. According to this passage, which of the following word can best describe Quan?A．Confident. B．Determined.C．Hospitable. D．Selfless.3. As many as 300 million full-time jobs around the world could be automated in some way by the newest wave of artificial intelligence that has made platforms like ChatGPT, according to Goldman Sachs economists.They predicted in a report Sunday that 18% of work globally could be computerized, with the effects caused more deeply in advanced economies than emerging markets. That’s partly because white-collar workers are seen to be more at risk than manual laborers. Administrative workers and lawyers are exp ected to be most affected, the economists said, compared to the “little effect” seen on physically demanding or outdoor occupations, such as construction and repair work.In the United States and Europe, about two-thirds of current jobs “are exposed to so me degree of AI automation,” and up to a quarter of all work could be done by AI completely, the bank estimates.Further use of such Al will likely lead to job losses, the Goldman Sachs economists wrote. But they noted that technological innovation that initially displaces workers has historically also created employment growth in the long run.While workplaces may shift, widespread adoption of Al could ultimately increase labor productivity —and boost global GDP by 7% annually over a 10-year period, according to Goldman Sachs economists.“Although the impact of AI on the labor market is likely to be significant, most jobs and industries are only partially exposed to automation and are thus more likely to be complemented rather than replaced by AI,” the economists added. “Most workers are employed in occupations that are partially exposed to AI automation and, following AI adoption, will likely apply at least some of their freed-up capacity toward productive activities that increase output.”Some US workers expected to be affected, for instance, 25% to 50% of their workload “can be replaced,” the researchers added. “The combination of significant labor cost savings, new job creation, and a productivity boost for non-displaced workers raises the possibility of a labor productivity boom like those that followed the emergence of earlier general-purpose technologies like the electric motor and personal computer.”1. Who are less likely to be affected by AI automation according to Paragraph 2?A．Lawyers. B．Repairmen.C．White-collar workers. D．Administrative workers.2. What can we learn about AI according to Goldman Sachs economists?A．AI has caused huge job losses.B．AI may increase labor productivity.C．AI has replaced most jobs and industries.D．AI may cause little impact on the labor market.3. Why did the researchers mention some US workers in the last paragraph?A．To show the benefits of AI.B．To show using AI wasted a lot of money.C．To show AI had a bad effect on US workers.D．To show some US workers didn’t want to work.4. What’s the best title for the text?A．The Impacts of AI B．The Concept of AIC．The Development of AI D．The Achievements of AI4. When you can’t fit your entire workout into a busy day, do you think there’s no point in doing anything at all? You should rethink that mindset. Just 11 minutes of moderate-to-vigorous intensity aerobic activity per day could lower your risk of cancer, cardiovascular disease(心血管疾病) or premature death, a large new study has found.Aerobic activities include walking, dancing, running, jogging, cycling and swimming. You can estimate the inten sity level of an activity by your heart rate and how hard you’re breathing as you move. Higher levels of physical activity have been associated with lower rates of premature deathand chronic disease, according to past research. But how the risk levels for these outcomes are affected by the amount of exercise someone gets has been more difficult to determine. To explorethis impact, scientists largely from the University of Cambridge in the United Kingdom looked at data from 196 studies, amounting to more than 30 million adult participants who were followed for10 years on average.The study mainly focused on participants who had done the minimum recommended amount of 150 minutes of exercise per week, or 22 minutes per day. Compared with inactive participants, adultswho had done 150 minutes of moderate-to-vigorous aerobic physical activity per week had a 31% lower risk of dying from any cause, a 29% lower risk of dying from cardiovascular disease and a 15% lower risk of dying from cancer. The same amount of exercise was linked with a 27% lower risk of developing cardiovascular disease and 12% lower risk when it came to cancer.“This is a convincing systematic review of existing research,” said CNN Medical Analyst Dr. Leana Wen, an emergency physician and public health professor at George Washington University, who wasn’t involved in the research. “We already knew that there was a strong correlation between increased physical activity and reduced risk for cardiovascular disease, cancer and premature death. This research confirms it, and furthermore states that a smaller amount than the 150 minutes of recommended exercise a week can help.”1. Why did the scientists from the University of Cambridge do this research?A．To confirm the past research.B．To encourage people to do more exercise.C．To find out how the amount of exercise impact the risk levels.D．To explore the relationship between daily exercise and risk levels.2. How did the scientists reach their conclusion?A．By conducting genetic research.B．By analyzing data from past research.C．By comparing different groups of participants.D．By collecting a mass of data from science website.3. What can we learn from this study?A．Inactive participants had higher risk of dying from cancer.B．People should take exercise for about 22 minutes every day.C．The scientists suggested people exercise at most 150 minutes per week.D．Moderate-to-vigorous aerobic physical activity was the best exercise for adults.4. What is the Dr. Leana Wen’s attitude towards this research?A．Critical. B．Indifferent.C．Sceptical. D．Positive.5. How do you like your eggs in the morning? Fried, baked or boiled? 1 . Here’s our top pick of breakfast ideas to wake up your taste buds.Add some avocado.The popularity of the humble avocado has increased in recent years. Not only does it pair perfectly with bacon, but research suggests avocado can actually help to speed up your metabolism(新陈代谢). 2 .Try inventive combinations.3 . Take a clue out of Virginia Guzman’s book and try adding olives to ham and cheese to give your sandwich a salty kick. And who says you can’t eat cake for breakfast? Food bloggers May Lee made this healthy breakfast cake by mixing yogurt with apple and oat flour.See your fridge resourcefully.Breakfast can be a meal, or it can be a vehicle for reinventing leftovers into new taste combinations.4 ? Fry it with onion, chili and turmeric for a quick version of uggani, a light but filling rice breakfast popular in the Rayalaseema region of southern India.5 .We’d all love to hop on a plane for breakfast, but in today’s cities chances are that you probably won’t need to adventure too far to taste international flavors. At the same time, bring global classics to your own kitchen is a great choice.6. Nelly Cheboi, the founder of Kenyan recycling company, TechLit Africa, has been named CNN’s Hero of the Year for her great work across Africa. Growing up in ______ in rural Kenya. she watched her mother work tirelessly so that she and her three sisters could ______ school. From an early age, Cheboi realized her family, along with others in their village, was ______ in a circle that left them little hope.______ , in 2012. Nelly Cheboi received a scholarship to Augustana College that changed her life. But she began her studies with ______ computer experience. She handwrote papers and ______ to transeribe (眷写)them on a computer. She said she d idn’t feel ______ using a computer until she______ a computer course for her maths major.Gradually, Cheboi was interested in ______ science and began a career in the field. ______ good computer skills, she could find jobs and make money by doing what she loved. She knew she wanted to make contributions to her hometown, and that is how TechLit Africa was ______ .“It was just unfair that a young generation in my hometown was ______ . I built a school, trying to see if I could include computer science as a part of kids’ education.” Cheboi said, “The program was going really ______ , but then I realized that building schools was really hard because it was so difficult to ______ money.”Cheboi and her partners also realized that they could reach more students by ______ computer training into local schools. They shipped more than 40 ______ computers that had been ______ to them by tech companies to Kenya. Now, since the non-profit organization has grown, it continues to work with various companies to clean up the ______ in the computers and then send them to Africa.Through Cheboi’s ______ , the students in Africa love learning about computers, and in turn they are e ______ skills that help them get out of poverty.1.A．happiness B．comfort C．wealth D．poverty2.A．change B．quit C．attend D．leave3.A．stuck B．injured C．cheated D．forced4.A．Easily B．Fortunately C．Sadly D．Suddenly 5.A．much B．little C．rich D．unusual6.A．struggled B．decided C．pretended D．promised 7.A．embarrassed B．surprised C．disappointed D．comfortable 8.A．took B．failed C．led D．missed9.A．mathematics B．physics C．chemistry D．computer 10.A．Instead of B．Regardless of C．Thanks to D．In addition to 11.A．studied B．founded C．abandoned D．shared12.A．left behind B．looked after C．let out D．dealt with 13.A．well B．badly C．unexpectedly D．terribly 14.A．make B．collect C．count D．borrow15.A．proving B．discussing C．introducing D．receiving 16.A．damaged B．new C．recycled D．modern 17.A．sold B．lent C．returned D．donated 18.A．hardware B．data C．screen D．pictures19.A．encouragement B．experiments C．exercises D．efforts20.A．believing B．needing C．gaining D．teaching7. 阅读下面短文，在空白处填入1个适当的单词或括号内单词的正确形式。

四川成都外国语学校2025届高三第二次调研英语试卷注意事项：1．答卷前，考生务必将自己的姓名、准考证号填写在答题卡上。

2．回答选择题时，选出每小题答案后，用铅笔把答题卡上对应题目的答案标号涂黑，如需改动，用橡皮擦干净后，再选涂其它答案标号。

回答非选择题时，将答案写在答题卡上，写在本试卷上无效。

3．考试结束后，将本试卷和答题卡一并交回。

第一部分（共20小题，每小题1.5分，满分30分）1．The new local law in Nanjing says parents not physically harm young children or expose them tolong-term hunger as a punishment.A．can B．shallC．will D．need2．—Mum, do you mind if I invite some friends to my birthday party?—______. It will be more interesting.A．By no means B．Yes, of courseC．Don’t worry D．No doubt.3．Given the huge gap _______ economic development and cultural consciousness, young people find big cities are safer than small towns.A．in view of B．in case of C．in consequence of D．in respect of4．Acceptance is not about liking a situation. It is about acknowledging all that has been lost and ________ to live with that loss.A．learning B．learnedC．to learn D．having learned5．It is unwise to disturb one who is devoted to his work. Just _____.A．face the music B．fly off the handleC．eat your words D．bite your tongue6．______much pressure the U.S. government put on the Chinese government, China would stickto its own policy of exchange rate.A．However B．Wherever C．Whatever D．Whoever7．---How was your trip to Xi'an last month？--_____________. It was raining cats and dogs during my stay there.A．Wonderful B．ExcitingC．Not bad D．It couldn't be worse8．The matches of the FIFA Women’s World Cup will be played in 2019 all around France, whose men’s team _____ the 2018 World Cup.A．wins B．wonC．has won D．had won9．Mike was usually so careful, this time he made a small mistake.A．yet B．still C．even D．thus10．The news came as no surprise to me. I ______ for some time that the factory was going to shut down.A．had known B．knewC．have known D．know11．The steamboat was fully furnished with life preservers. The passengers might be saved __________ accidents. A．in spite of B．instead ofC．in case of D．in place of12．NASA has made a ________ that our earth has no threat associated with the film 2012 which is based on pure myths. A．clarification B．classification C．identification D．presentation13．Daniel’s family ________ their holiday in Huangshan this time next week.A．are enjoying B．are to enjoy C．will enjoy D．will be enjoying14．----I feel cold. ____ I close the window?----Sure. Go ahead!A．Shall B．Need C．Would D．Should15．People tend to love agricultural products ________ without the use of fertilizers, pesticides or chemical additives. A．growing B．grownC．being grown D．having been grown16．Jane’s pale face suggested that she ______ ill and her parents suggested that she ______ a medical exam.A．be; should have B．was; haveC．should be; had D．was; had17．--- Have you heard that they are working around the clock to compete for the prize?--- Don’t worry. We are ready to the challenge.A．build up B．take upC．stick to D．lead to18．Like all parents in the world，we want you to grow up in a world __________ is full of love and kindness. A．where B．thatC．when D．what19．—You look sleepy today.—__________ not to miss the flight, I didn't dare to close my eyes the whole night.A．Reminded B．Being remindedC．Reminding D．Having reminded20．The problem lies in______ we’re now giving him a fish, not teaching him how to fish.A．what B．thatC．which D．if第二部分阅读理解（满分40分）阅读下列短文，从每题所给的A、B、C、D四个选项中，选出最佳选项。

2022-2023学年陕西省西安市铁一中学高二下学期5月月考英语试题1. Activities for National Manufacturing DayThe STEM (Science, Technology, Engineering and Mathematics) Careers Coalition (职业联盟) offers students and families new STEM resources to explore the world of modern manufacturing. With over 4 million manufacturing roles predicted to be available in the next ten years, the new resources from the coalition connect today’s students to the manufacturing careers o f tomorrow. National Manufacturing Day occurs on annually the first Friday of October to motivate today’s students to become the next generation of innovators leading the manufacturing industry. In order to support this celebration, the coalition offers three different collections to all students, educators, and families on modern manufacturing that support learning wherever it takes place. The following resources ate available to all at no cost：Manufacturing-focused Career ProfilesExplore the profiles of manufacturing professionals using the skills they learned at school to become the kind of problem solvers that make a difference. Make the connection from the classroom to careers and find out how all students can make it in manufacturing.Hands-on Student ActivitiesFrom innovating food packaging to discovering the principles of accurate design to exploring water sustainability, at-home, hands-on learning activities help students take STEM skills from theory to practice.Classroom ActivitiesAccess the no-cost, standard classroom activities to support future career success for all students. Each, activity features important STEM skills and a step-by-step guide for promoting activities into classroom.Virtual Interactive Field TripsEach virtual experience features accompanying educator resources and student activities that make it easy for teachers to put these manufacturing events into the learning experiences they design and deliver daily.All resources are available at no cost at stemcareerscoalition. org.1. What is the purpose of the STEM Careers Coalition?A．To count the vacant jobs in manufacturing. B．To guide students to work on manufacturing.C．To report the current state of manufacturing. D．To offer students pre-job training in manufacturing.2. Which activity will introduce manufacturing masters to students?A．Classroom Activities. B．Hands-on Student ActivitiesC．Virtual Interactive Field Trips. D．Manufacturing-focused Career Profiles. 3. What do the activities have in common?A．The activities are free of charge. B．All of the activities are virtual.C．Only students practice in the activities. D．The activities are only experienced online.2. For some people, October is Octobear. On October 5, Katmai National Park and Preserve in southern Alaska kicked off Fat Bear Week, when fans compare before and after photos of bears to vote for the one they think has gained the most weight before they bed down for the long freezing winter. Bear 747, also known as “Bear Force One”, took the first-place spot with 68, 105 votes. It weighed around 1, 400 pounds.Fat Bear Week started in 2014. At first, it was just Fat Bear Tuesday. Mike Fitz, a former park keeper at Katmai, noticed that live webcams showing the bears generated a lot of online comments, so he let people vote for their favorite fat bear on the Internet. The one-day event attracted 1, 700 votes. In 2015, it was extended to a week. Last year, nearly 800, 000 people got involved, turning it into a global campaign.The contest serves two main purpose s. First, some of America’s national parks are in remote and undeveloped areas, which are difficult or costly to reach. Fat Bear Week brings Alaska’s wilderness to fans’ computer screens. “It’s not limited to the fortunate few who can go to the river anymore.” Fitz said.Second, Fat Bear Week brings attention to the bears and the ecosystems they live in. The 2, 200 bears of Katmai are strong for feeding on some of the healthiest salmon (三文鱼) in the world, said Sara Wolman, a former park keeper. Salmon in the Pacific Northwest are suffering from overfishing, dam construction and warming rivers due to climate change. Luckily, Brooks River, which Katmai’s bears like to fish in, has been free from these threats so far.Fat Bear Week has spread like viruses. Fa ns and creators say it’s because it shows a conservation success story. For one week, people don’t have to focus on climate change or habitat loss. “Maybe things aren’t super great all the time in the world,” said Felicia Jimenez, who is a current Katmaik eeper. “But there are some really fat bears in Alaska.”1. Why was Bear 747 the winner?A．It was the heaviest.B．It was the most famous.C．It gained the most pounds.D．It presented the best photos.2. What is the purpose of paragraph 2?A．To praise Mike Fitz for his work.B．To review the history of the event.C．To show the popularity of fat bears.D．To explain the role of live webcams.3. What can we learn about Katmai’s bears?A．They bring tourists to the park.B．They have a stable food source.C．They remain difficult to be seen.D．They face a population decline.4. Which can be the best title for the text?A．Fat Bear Week: Conservation Is JoyfulB．Brown Bears: Winter Survival Is CrucialC．Bear 747: A Fat Yet Healthy ChampionD．Katmai’s Bears: A Special Beauty Contest3. Years earlier, I’d been a trainee in a lab, which stuck to a traditional format. The lab head would spend much time asking the presenter a series of pointed questions. Presenters would need to know extremely small details about articles they were citing and present their research using picture-perfect analyses and graphs. So the presentation was an untoward thing to almost anyone.When I started my own lab, I decided to change the routine by being friendly and welcoming while asking my trainees challenging questions about their science. But for 6 years, I felt I hadn’t created the lab environment I wanted.The turning point came during the pandemic. It hit home to me that one’s life isn’t endless and that I need to make the most of the time I have. I decided that I wanted to become a better professor—to make a mark by training the next generation of scientists.In my personal life, I had benefited from listening to talks by motivational speakers. So I decided to start there. At the next lab meeting, I showed my students a video about happiness, hoping it would help them in their personal life and give us something light to discuss. I wasn’t sure how they’d respond, hut I was pleased to discover that they were interested in discussing the advice in the video afterward. In the end, I asked them whether they’d like to do similar activities in future meetings, and they said yes.From then on, I began every lab meeting with a 20-minute team building session. My lab members and I do many activities—including analyzing and appreciating poetry. These sessions have eased tensions and opened minds, helping foster more participation later in the meeting.So far, I have been hopeful about the lab environment we’re creating. My greates t wish is to see my trainees become their best selves, understand who they are and what they want as well as reach their career goals. I am proud of the change and the difference I’ve made.1. What does the underlined word “untoward” in paragraph 1 probabl y mean?A．Harmonious. B．Embarrassing. C．Stressful. D．Appealing.2. How did the pandemic affect the author?A．He no longer wasted his time. B．He decided to become a professor.C．He realized the benefit of inspiring talks. D．He wanted to make more contributions.3. What is paragraph 4 mainly about?A．The change the author made. B．A video the students liked.C．The benefit the author got from others. D．A proposal the students put forward.4. What message does the author mainly want to deliver?A．Team building sessions can bring unexpected benefits.B．One should have the courage to make a change.C．Professors are responsible for teamwork.D．Motivational talks are the origin of inspiration.4. A remarkable new study on how whales behaved when attacked by humans in the 19th century has implications for the way they react to changes caused by humans in the 2Ist century.The paper is authored by Whitehead and Rendellt at Dalhousie University and their research addresses an age- -old question: if whales are so smart, why did they hang around to be killed? The answer? They didn't. Using newly digitised (数字化的) logbooks detailing the hunting of whales in the north Pacific, the authors discovered that within just a few years, the strike rate of the whal ers’ harpoons(捕鲸者的鱼叉) fell by 58%. This simple fact leads to an astonishing conclusion: that information about what was happening to them was being collectively shared among the whales, who made vital changes to their behaviour. They learned quickly from their mistakes.“Sperm whales have a traditional way of reacting to attacks from orca (杀人鲸),” notes Whitehead. Before humans, orca were their only predators (捕食者), against whom sperm whales form defensive circles, their powerful taills held outwards to keep predators at bay, “But such techniques just made it easier for the whalers to kill them,” says Whitehead.Sperm whales are highly socialised animals, able to communicate over great distances. Information about the new dangers may have been passed on in the same way they share knowledge about feeding grounds. They also possess the largest brain on the planet. It is not hard to imagine that they understood what was happening to them.The hunters themselves realised the whales’efforts to escape. They saw that the animals appeared to communicate the threat within their attacked groups. Abandoning their usual defensive formations, the whales swam upwind to escape the hunters, ships, themselves wind-powered.Now, just as whales are beginning to recover from the industrial destruction by 20th-century whaling fleets, whose steamships and grenade harpoons no whale could escape from, they face new threats created by our technology. “They’re having to learn not to get hit by ships, cope with thedepredations (劫掠) of long line fishing, the changing source of their food due to climate change,”Whitehead says. “The same sort of urgent social learning the animals experienced in the whale wars of two centuries ago is reflected in the way they negotiate today's uncertain world.”1. What is the new study mainly about?A．Whales’ social lives.B．Whales’emotional intelligence.C．Whales’ reaction to climate changes.D．Whales’ behavior under human attack.2. What caused whales to make changes to escape the hunters’ ship?A．The wind in their favor. B．Their powerful physical strength.C．The shared ship attack information. D．Their usual defensive formations.3. What does the author intend to do in Paragraph 5?A．State possible reasons. B．Add background information.C．Summarize the previous paragraphs. D．Introduce a new topic for discussion.4. What's Whitehead’s attitude towards whales’ future survival?A．Pessimistic. B．Unclear. C．Cautious. D．Optimistic.5. Vegan AgricultureVegan farming (全素农业) has become more and more popular. It is one of the most environmentally-friendly forms of agriculture. Vegan farming is a good way to grow plants such as vegetables without using animal-derived materials such as their waste. 1 Such an approach to farming also helps preserve the environment and regain soil richness and improve its biodiversity.2 Organic farming uses natural products to grow plants — that can include even animal waste as fertilizers. On the other hand, vegan agriculture rejects animal-derived products and usually sticks with plant-based organic compounds, which means that, in general, vegan agriculture has stricter rules than organic farming.Additionally, vegan farming usually chooses more natural ways to protect the plants, like breaking cycles of plants’ diseases with mixed cropping (混作), using mechanical barriers such as nets, or even attracting opposing organisms to fight the harmful ones. 3 However, they might be less effective against certain plant diseases or pests.One of the reasons to invest in vegan agriculture is that the vegan way of farming replaces synthetic (合成的) pesticides and uses organic pesticides or other non-chemical methods to protect the crops. By contrast, in conventional agriculture, synthetic pesticides are on a very high level. 4In the future, it is of great significance not to rely on animals’ waste for feeding plants. Doing so is not only beneficial to vegans. 5 Even if today’s methods of vegan agriculture might not be perfect, scientists worldwide, together with vegan farmers, are working towards developing plant-based solutions as alternatives to animal-derived fertilizers.6. A group of teenagers in Chicago’s Austin neighborhood were looking for a way to uplift their marginalized (被边缘化的) West Side community. With a little help from their friends, these young entrepreneurs (创业者) ______ an old store into Austin Harvest, a food market ______ healthy food for their undeserved neighborhood.For areas like Austin, classified as “food deserts”, fresh produce and healthy food are difficult to______ even at the best of times. The situation ______ when several area grocery stores were forced to ______ temporarily after being destroyed. Thus, one of the ______ that concerned the teens most was the ______ of healthy food in the area, which was the ______ of years of racism. In their community, Austin Harvest has since sprung to life, where there were only two food markets. “Food is a(n) ______ need,” Azariah Baker, one of the teens said, “but it’s also something ______ to us.”Their project got ______ from a lot of professional athletes. “People care. It’s a time for people to show up. I think our world has ______ .” Baker said, “So for us, to be able to come together and say we’re going to lead that change is ______ .” Together, they raised $500,000.The vision for Austin Harvest was shaped and implemented (实施) by the teens. “We’ve been behind the project ______ ,” Baker said. “We’ve ______ how we want to show our market — where w e want our market to be, what we sell, and what we look like. It is we that ______ it.”Taking a “teach someone to fish rather than give someone a fish” approach, The Hatchery Chicago, a food business incubator (孵化器), also helped to ______ lessons in real-world business skills including licensing and customer service, as well as cooking classes ______ helping interested teens work toward careers in the ______ industry.This is a real entrepreneurship opportunity for the teens and also an opportunity for them to bring food ______ to their marginalized neighborhood.1.A．turned B．placed C．divided D．forced2.A．make B．grow C．provide D．check3.A．get round B．come by C．take over D．make up 4.A．started B．differed C．improved D．worsened 5.A．close B．separate C．move D．return6.A．doubts B．issues C．mistakes D．accidents 7.A．type B．taste C．sale D．shortage 8.A．result B．test C．excuse D．solution 9.A．immediate B．emotional C．basic D．personal 10.A．unrecognizable B．inaccessible C．indescribable D．unimportant 11.A．permission B．protection C．backing D．warning 12.A．opened B．fallen C．changed D．formed 13.A．easy B．meaningful C．obvious D．demanding 14.A．completely B．calmly C．secretly D．cautiously 15.A．said B．spoke C．remarked D．discussed 16.A．rebuild B．advise C．join D．run17.A．find B．discuss C．attend D．offer18.A．aimed at B．attached to C．concerned about D．equipped with19.A．hotel B．health C．food D．service20.A．chain B．justice C．inspection D．planning7. The________(major) of people prefer peace to war. (所给词的适当形式填空)8. Before the volcano erupted, it had been a________(boom) city. (所给词的适当形式填空)9. The little boy has a strong________(object) to getting up so early. (所给词的适当形式填空)10. The guard ________(forbid) us to look out of the window when the train was moving. (所给词的适当形式填空)11. Not only are we at the forefront of electronics, but we’ve receivedworldwide________(recognize) for our advances in chemicals and engineering as well. (所给词的适当形式填空)12. Even though he was guilty, the________(mercy)judge did not send him to prison. (所给词的适当形式填空)13. There is no doubt that watching this screen________(adapt)of ”Gone with The Wind will certainly be a wonderful experience. (所给词的适当形式填空)14. The management decided to settle the strike by________(compromise)with the trade union over the workers’ pay demand. (所给词的适当形式填空)15. Her years of archery has allowed her to fire multiple arrows with keen________(accurate). (所给词的适当形式填空)16. The ambassador said the move was part of a deal to swap prisoners in Russia for the accused spies________(arrest) in the U.S. (所给词的适当形式填空)17. When he was________(选举) president, a reporter went back to his hometown to interview his mother. (根据汉语提示单词拼写)18. It________(发生，出现) to me that I had left the door unlocked. (根据汉语提示单词拼写)19. Learning is defined as a conscious process of________(积累) knowledge of a second language usually obtained in school settings. (根据汉语提示单词拼写)20. Up to now, new school students of________(义务的，强制) education in 90 percent of the provinces in the country has begun to use the new curriculum. (根据汉语提示单词拼写)21. ________(一般地) speaking, generation gaps result from not being able to understand each other.(根据汉语提示单词拼写)22. The audience warmly ______(鼓掌) when the performance came to an end. (根据汉语提示单词拼写)23. Europe is the home to symphonic music and also home to opera. It has been a cradle ofmany________(杰出的，才华横溢的) music composers. (根据汉语提示单词拼写)24. The hotel features a lovely dining-room________(俯视) the lake. (根据汉语提示单词拼写)25. Teacher Li insisted on working________(不管，不顾) of the illness. It may be impossible to ask her to go to bed to have a rest. (根据汉语提示单词拼写)26. Coffee has a history________(追溯到) back to at least the 9th century and has been a catalystfor social interaction across cultures and eras. (根据汉语提示单词拼写)27. 阅读下面材料, 在空白处填入适当的内容(1个单词)或括号内单词的正确形式。

Becoming a Scientist:The Roleof Undergraduate Research in Students’Cognitive,Personal, and Professional DevelopmentANNE-BARRIE HUNTER,SANDRA URSEN,ELAINE SEYMOUR Ethnography&Evaluation Research,Center to Advance Research and Teaching in the Social Sciences,University of Colorado,Campus Box580,Boulder,CO80309,USAReceived9November2005;revised2May2006;accepted2June2006DOI10.1002/sce.20173Published online12October2006in Wiley InterScience().ABSTRACT:In this ethnographic study of summer undergraduate research(UR)expe-riences at four liberal arts colleges,where faculty and students work collaboratively on aproject of mutual interest in an apprenticeship of authentic science research work,analysisof the accounts of faculty and student participants yields comparative insights into thestructural elements of this form of UR program and its benefits for parison ofthe perspectives of faculty and their students revealed considerable agreement on the nature,range,and extent of students’UR gains.Specific student gains relating to the process of “becoming a scientist”were described and illustrated by both groups.Faculty framed these gains as part of professional socialization into the sciences.In contrast,students emphasizedtheir personal and intellectual development,with little awareness of their socialization intoprofessional practice.Viewing studyfindings through the lens of social constructivist learn-ing theories demonstrates that the characteristics of these UR programs,how faculty practiceUR in these colleges,and students’outcomes—including cognitive and personal growth and the development of a professional identity—strongly exemplify many facets of these theo-ries,particularly,student-centered and situated learning as part of cognitive apprenticeshipin a community of practice.C 2006Wiley Periodicals,Inc.Sci Ed91:36–74,2007Correspondence to:Anne-Barrie Hunter;e-mail:abhunter@Contract grant sponsor:NSF-ROLE grant(#NSF PR REC-0087611):“Pilot Study to Establish the Nature and Impact of Effective Undergraduate Research Experiences on Learning,Attitudes and Career Choice.”Contract grant sponsor:Howard Hughes Medical Institute special projects grant,“Establishing the Processes and Mediating Factors that Contribute to Significant Outcomes in Undergraduate Research Experiences for both Students and Faculty:A Second Stage Study.”This paper was edited by former Editor Nancy W.Brickhouse.C 2006Wiley Periodicals,Inc.BECOMING A SCIENTIST37INTRODUCTIONIn1998,the Boyer Commission Report challenged United States’research universities to make research-based learning the standard of students’college education.Funding agencies and organizations promoting college science education have also strongly recommended that institutions of higher education provide greater opportunities for authentic,interdis-ciplinary,and student-centered learning(National Research Council,1999,2000,2003a, 2003b;National Science Foundation[NSF],2000,2003a).In line with these recommen-dations,tremendous resources are expended to provide undergraduates with opportunities to participate in faculty-mentored,hands-on research(e.g.,the NSF-sponsored Research Experience for Undergraduates[REU]program,Howard Hughes Medical Institute Science Education Initiatives).Notwithstanding widespread belief in the value of undergraduate research(UR)for stu-dents’education and career development,it is only recently that research and evaluation studies have produced results that begin to throw light on the benefits to students,faculty,or institutions that are generated by UR opportunities(Bauer&Bennett,2003;Lopatto,2004a; Russell,2005;Seymour,Hunter,Laursen,&DeAntoni,2004;Ward,Bennett,&Bauer, 2002;Zydney,Bennett,Shahid,&Bauer,2002a,2002b).Other reports focus on the effects of UR experiences on retention,persistence,and promotion of science career pathways for underrepresented groups(Adhikari&Nolan,2002;Barlow&Villarejo,2004;Hathaway, Nagda,&Gregerman,2002;Nagda et al.,1998).It is encouraging tofind strong convergence as to the types of gains reported by these studies(Hunter,Laursen,&Seymour,2006).How-ever,we note limited or no discussion of some of the stronger gains that we document,such as students’personal and professional growth(Hunter et al.,2006;Seymour et al.,2004) and significant variation in how particular gains(especially intellectual gains)are defined. Ongoing and current debates in the academic literature concerning how learning occurs, how students develop intellectually and personally during their college years,and how communities of practice encourage these types of growth posit effective practices and the processes of students’cognitive,epistemological,and interpersonal and intrapersonal de-velopment.Although a variety of theoretical papers and research studies exploring these topics are widely published,with the exception of a short article for Project Kaleidoscope (Lopatto,2004b),none has yet focused on intensive,summer apprentice-style UR experi-ences as a model to investigate the validity of these debates.1Findings from this research study to establish the nature and range of benefits from UR experiences in the sciences,and in particular,results from a comparative analysis of faculty and students’perceptions of gains from UR experiences,inform these theoretical discussions and bolsterfindings from empirical studies in different but related areas(i.e.,careers research,workplace learning, graduate training)on student learning,cognitive and personal growth,the development of professional identity,and how communities of practice contribute to these processes. This article will presentfindings from our faculty andfirst-round student data sets that manifest the concepts and theories underpinning constructivist learning,development of professional identity,and how apprentice-style UR experience operates as an effective community of practice.As these bodies of theory are central tenets of current science education reform efforts,empirical evidence that provides clearer understanding of the actual practices and outcomes of these approaches inform national science education pol-icy concerns for institutions of higher learning to increase diversity in science,numbers of students majoring in science,technology,engineering,or mathematics(STEM)disci-plines,student retention in undergraduate and graduate STEM programs and their entry 1David Lopatto was co-P.I.on this study and conducted quantitative survey research on the basis of our qualitativefindings at the same four liberal arts colleges.Science Education DOI10.1002/sce38HUNTER ET AL.into science careers,and,ultimately,the production of greater numbers of professional scientists.To frame discussion offindings from this research,we present a brief review of theory on student learning,communities of practice,and the development of personal and professional identity germane to our data.CONSTRUCTIVIST LEARNING,COMMUNITIES OF PRACTICE,AND IDENTITY DEVELOPMENTApprentice-style URfits a theoretical model of learning advanced by constructivism, in which learning is a process of integrating new knowledge with prior knowledge such that knowledge is continually constructed and reconstructed by the individual.Vygotsky’s social constructivist approach presented the notion of“the zone of proximal development,”referencing the potential of students’ability to learn and problem solve beyond their current knowledge level through careful guidance from and collaboration with an adult or group of more able peers(Vygotsky,1978).According to Green(2005),Vygotsky’s learning model moved beyond theories of“staged development”(i.e.,Piaget)and“led the way for educators to consider ways of working with others beyond the traditional didactic model”(p.294).In social constructivism,learning is student centered and“situated.”Situated learning,the hallmark of cultural and critical studies education theorists(Freire,1990; Giroux,1988;Shor,1987),takes into account students’own ways of making meaning and frames meaning-making as a negotiated,social,and contextual process.Crucial to student-centered learning is the role of educator as a“facilitator”of learning.In constructivist pedagogy,the teacher is engaged with the student in a two-way,dialog-ical sharing of meaning construction based upon an activity of mutual ve and Wenger(1991)and Wenger(1998)extended tenets of social constructivism into a model of learning built upon“communities of practice.”In a community of practice“newcomers”are socialized into the practice of the community(in this case,science research)through mutual engagement with,and direction and support from an“old-timer.”Lave and Wenger’s development of the concept and practice of this model centers on students’“legitimate pe-ripheral participation.”This construct describes the process whereby a novice is slowly,but increasingly,inducted into the knowledge and skills(both overt and tacit)of a particular practice under the guidance and expertise of the master.Legitimate peripheral participation requires that students actively participate in the authentic practice of the community,as this is the process by which the novice moves from the periphery toward full membership in the community(Lave&Wenger,1991).Similar to Lave and Wenger’s communities of practice, Brown,Collins,and Duguid(1989)and Farmer,Buckmaster,and LeGrand(1992)describe “cognitive apprenticeships.”A cognitive apprenticeship“starts with deliberate instruction by someone who acts as a model;it then proceeds to model-guided trials by practition-ers who progressively assume more responsibility for their learning”(Farmer et al.,1992, p.42).However,these latter authors especially emphasize the importance of students’ongoing opportunities for self-expression and reflective thinking facilitated by an“expert other”as necessary to effective legitimate peripheral participation.Beyond gains in understanding and exercising the practical and cultural knowledge of a community of practice,Brown et al.(1989)discuss the benefits of cognitive ap-prenticeship in helping learners to deal capably with ambiguity and uncertainty—a trait particularly relevant to conducting science research.In their view,cognitive apprenticeship “teaches individuals how to think and act satisfactorily in practice.It transmits useful, reliable knowledge based on the consensual agreement of the practitioners,about how to deal with situations,particularly those that are ill-defined,complex and risky.It teachesScience Education DOI10.1002/sceBECOMING A SCIENTIST39‘knowledge-in-action’that is‘situated”’(quoted in Farmer et al.,1992,p.42).Green(2005) points out that Bowden and Marton(1998,2004)also characterize effective communities of practice as teaching skills that prepare apprentices to negotiate undefined“spaces of learning”:“the‘expert other’...does not necessarily‘know’the answers in a traditional sense,but rather is willing to support collaborative learning focused on the‘unknown fu-ture.’In other words,the‘influential other’takes learning...to spaces where the journey itself is unknown to everyone”(p.295).Such conceptions of communities of practice are strikingly apposite to the processes of learning and growth that we have found among UR students,particularly in their understanding of the nature of scientific knowledge and in their capacity to confront the inherent difficulties of science research.These same issues are central to Baxter Magolda’s research on young adult development. The“epistemological reflection”(ER)model developed from her research posits four categories of intellectual development from simplistic to complex thinking:from“absolute knowing”(where students understand knowledge to be certain and view it as residing in an outside authority)to“transitional knowing”(where students believe that some knowledge is less than absolute and focus onfinding ways to search for truth),then to“independent knowing”(where students believe that most knowledge is less than absolute and individuals can think for themselves),and lastly to“contextual knowing”(where knowledge is shaped by the context in which it is situated and its veracity is debated according to its context) (Baxter Magolda,2004).In this model,epistemological development is closely tied to development of identity. The ER model of“ways of knowing”gradually shifts from an externally directed view of knowing to one that is internally directed.It is this epistemological shift that frames a student’s cognitive and personal development—where knowing and sense of self shift from external sources to reliance upon one’s own internal assessment of knowing and identity. This process of identity development is referred to as“self-authorship”and is supported by a constructivist-developmental pedagogy based on“validating students as knowers, situating learning in students’experience,and defining learning as mutually constructed meaning”(Baxter Magolda,1999,p.26).Baxter Magolda’s research provides examples of pedagogical practice that support the development of self-authorship,including learning through scientific inquiry.As in other social constructivist learning models,the teacher as facilitator is crucial to students’cognitive and personal development:Helping students make personal sense of the construction of knowledge claims and engagingstudents in knowledge construction from their own perspectives involves validating thestudents as knowers and situating learning in the students’own perspectives.Becoming socialized into the ways of knowing of the scientific community and participating in thediscipline’s collective knowledge creation effort involves mutually constructing meaning.(Baxter Magolda,1999,p.105)Here Baxter Magolda’s constructivist-developmental pedagogy converges with Lave and Wenger’s communities of practice,but more clearly emphasizes students’development of identity as part of the professional socialization process.Use of constructivist learning theory and pedagogies,including communities of practice, are plainly evident in the UR model as it is structured and practiced at the four institutions participating in this study,as we describe next.As such,the gains identified by student and faculty research advisors actively engaged in apprentice-style learning and teaching provide a means to test these theories and models and offer the opportunity to examine the processes,whereby these benefits are generated,including students’development of a professional identity.Science Education DOI10.1002/sce40HUNTER ET AL.THE APPRENTICESHIP MODEL FOR UNDERGRADUATE RESEARCH Effective UR is defined as,“an inquiry or investigation conducted by an undergraduate that makes an original intellectual or creative contribution to the discipline”(NSF,2003b, p.9).In the“best practice”of UR,the student draws on the“mentor’s expertise and resources...and the student is encouraged to take primary responsibility for the project and to provide substantial input into its direction”(American Chemical Society’s Committee on Professional Training,quoted in Wenzel,2003,p.1).Undergraduate research,as practiced in the four liberal arts colleges in this study,is based upon this apprenticeship model of learning:student researchers work collaboratively with faculty in conducting authentic, original research.In these colleges,students typically underwent a competitive application process(even when a faculty member directly invited a student to participate).After sorting applications, and ranking students’research preferences,faculty interviewed students to assure a good match between the student’s interests and the faculty member’s research and also between the faculty member and the student.Generally,once all application materials were reviewed (i.e.,students’statements of interest,course transcripts,grade point averages[GPA]), faculty negotiated as a group to distribute successful applicants among the available summer research advisors.Students were paid a stipend for their full-time work with faculty for 10weeks over summer.Depending on the amount of funding available and individual research needs,faculty research advisors supervised one or more students.Typically,a faculty research advisor worked with two students for the summer,but many worked with three or four,or even larger groups.In most cases,student researchers were assigned to work on predetermined facets of faculty research projects:each student project was open ended,but defined,so that a student had a reasonable chance of completing it in the short time frame and of producing useful results.Faculty research advisors described the importance of choosing a project appropriate to the student’s“level,”taking into account their students’interests,knowledge, and abilities and aiming to stretch their capacities,but not beyond students’reach.Research advisors were often willing to integrate students’specific interests into the design of their research projects.Faculty research advisors described the intensive nature of getting their student re-searchers“up and running”in the beginning weeks of the program.Orienting students to the laboratory and to the project,providing students with relevant background information and literature,and teaching them the various skills and instrumentation necessary to work effectively required adaptability to meet students at an array of preparation levels,advance planning,and a good deal of their time.Faculty engaged in directing UR discussed their role as facilitators of students’learning.In the beginning weeks of the project,faculty advisors often worked one-on-one with their students.They provided instruction,gave “mini-lectures,”explained step by step why and how processes were done in particular ways—all the time modeling how science research is done.When necessary,they closely guided students,but wherever possible,provided latitude for and encouraged students’own initiative and experimentation.As the summer progressed,faculty noted that,based on growing hands-on experience,students gained confidence(to a greater or lesser degree)in their abilities,and gradually and increasingly became self-directed and able,or even eager, to work independently.Although most faculty research advisors described regular contact with their student researchers,most did not work side by side with their students everyday.Many research advisors held a weekly meeting to review progress,discuss problems,and make sure students(and the projects)were on the right track.At points in the research work,facultyScience Education DOI10.1002/sceBECOMING A SCIENTIST41 could focus on other tasks while students worked more independently,and the former were available as necessary.When students encountered problems with the research,faculty would serve as a sounding board while students described their efforts to resolve difficulties. Faculty gave suggestions for methods that students could try themselves,and when problems seemed insurmountable to students,faculty would troubleshoot with them tofind a way to move the project forward.Faculty research advisors working with two or more student researchers often used the research peer group to further their students’development.Some faculty relied on more-senior student researchers to help guide new ones.Having multiple students working in the laboratory(whether or not on the same project)also gave student researchers an extra resource to draw upon when questions arose or they needed help.In some cases,several faculty members(from the same or different departments)scheduled weekly meetings for group discussion of their research monly,faculty assigned articles for students to summarize and present to the rest of the group.Toward the end of summer, weekly meetings were often devoted to students’practice of their presentations so that the research advisor and other students could provide constructive criticism.At the end of summer,with few exceptions,student researchers attended a campus-wide UR conference, where they presented posters and shared their research with peers,faculty,and institution administrators.Undergraduate research programs in these liberal arts colleges also offered a series of seminars andfield trips that explored various science careers,discussed the process of choosing and applying to graduate schools,and other topics that focused on students’professional development.We thus found that,at these four liberal arts colleges,the practice of UR embodies the principles of the apprenticeship model of learning where students engage in active,hands-on experience of doing science research in collaboration with and under the auspices of a faculty research advisor.RESEARCH DESIGNThis qualitative study was designed to address fundamental questions about the benefits (and costs)of undergraduate engagement in faculty-mentored,authentic research under-taken outside of class work,about which the existing literature offers fewfindings and many untested hypotheses.2Longitudinal and comparative,this study explores:•what students identify as the benefits of UR—both following the experience,and inthe longer term(particularly career outcomes);•what gains faculty advisors observe in their student researchers and how their view of gains converges with or diverges from those of their students;•the benefits and costs to faculty of their engagement in UR;•what,if anything,is lost by students who do not participate in UR;and•the processes by which gains to students are generated.This study was undertaken at four liberal arts colleges with a strong history of UR.All four offer UR in three core sciences—physics,chemistry,and biology—with additional programs in other STEMfields,including(at different campuses)computer science,engi-neering,biochemistry,mathematics,and psychology.In the apprenticeship model of UR practiced at these colleges,faculty alone directed students in research;however,in the few2An extensive review and discussion of the literature on UR is presented in Seymour et al.(2004). Science Education DOI10.1002/sce42HUNTER ET AL.instances where faculty conducted research at a nearby institution,some students did have contact with post docs,graduate students,or senior laboratory technicians who assisted in the research as well.We interviewed a cohort of(largely)“rising seniors”who were engaged in UR in summer2000on the four campuses(N=76).They were interviewed for a second time shortly before their graduation in spring2001(N=69),and a third time as graduates in 2003–2004(N=55).The faculty advisors(N=55)working with this cohort of students were also interviewed in summer2000,as were nine administrators with long experience of UR programs at their schools.We also interviewed a comparison group of students(N=62)who had not done UR. They were interviewed as graduating seniors in spring2001,and again as graduates in 2003–2004(N=25).A comparison group(N=16)of faculty who did not conduct UR in summer2000was also interviewed.Interview protocols focused upon the nature,value,and career consequences of UR experiences,and the methods by which these were achieved.3After classifying the range of benefits claimed in the literature,we constructed a“gains”checklist to discuss with all participants“what faculty think students may gain from undergraduate research.”Dur-ing the interview,UR students were asked to describe the gains from their research experience(or by other means).If,toward the end of the interview,a student had not mentioned a gain identified on our“checklist,”the student was queried as to whether he or she could claim to have gained the benefit and was invited to add further com-ment.Students also mentioned gains they had made that were not included in the list. With slight alterations in the protocol,we invited comments on the same list of possi-ble gains from students who had not experienced UR,and solicited information about gains from other types of experience.All students were asked to expand on their an-swers,to highlight gains most significant to them,and to describe the sources of any benefits.In the second set of interviews,the same students(nearing graduation)were asked to reflect back on their research experiences as undergraduates,and to comment on the rel-ative importance of their research-derived gains,both for the careers they planned and for other aspects of their lives.In thefinal set of interviews,they were asked to of-fer a retrospective summary of the origins of their career plans and the role that UR and other factors had played in them,and to comment on the longer term effects of their UR experiences—especially the consequences for their career choices and progress, including their current educational or professional engagement.Again,the sources of gains cited were explored;especially gains that were identified by some students as arising from UR experiences but may also arise from other aspects of their college education.The total of367interviews represents more than13,000pages of text data.We are currently analyzing other aspects of the data and will reportfindings on additional topics, including the benefits and costs to faculty of their participation in UR and longitudinal and comparative outcomes of students’career choices.This article discussesfindings from a comparative analysis of all faculty and administrator interviews(N=80),withfindings from thefirst-round UR student interviews(N=76),and provides empirical evidence of the role of UR experiences in encouraging the intellectual,personal,and professional development of student researchers,and how the apprenticeship modelfits theoretical discussions on these topics.3The protocol is available by request to the authors via abhunter@.Science Education DOI10.1002/sceBECOMING A SCIENTIST43METHODS OF DATA TRANSCRIPTION,CODING,AND ANAL YSISOur methods of data collection and analysis are ethnographic,rooted in theoretical work and methodological traditions from sociology,anthropology,and social psychol-ogy(Berger&Luckman,1967;Blumer,1969;Garfinkel,1967;Mead,1934;Schutz& Luckman,1974).Classically,qualitative studies such as ethnographies precede survey or experimental work,particularly where existing knowledge is limited,because these meth-ods of research can uncover and explore issues that shape informants’thinking and actions. Good qualitative software computer programs are now available that allow for the multiple, overlapping,and nested coding of a large volume of text data to a high degree of complexity, thus enabling ethnographers to disentangle patterns in large data sets and to reportfindings using descriptive statistics.Although conditions for statistical significance are rarely met, the results from analysis of text data gathered by careful sampling and consistency in data coding can be very powerful.Interviews took between60and90minutes.Taped interviews and focus groups were transcribed verbatim into a word-processing program and submitted to“The Ethnograph,”a qualitative computer software program(Seidel,1998).Each transcript was searched for information bearing upon the research questions.In this type of analysis,text segments referencing issues of different type are tagged by code names.Codes are not preconceived,but empirical:each new code references a discrete idea not previously raised.Interviewees also offer information in spontaneous narratives and examples,and may make several points in the same passage,each of which is separately coded.As transcripts are coded,both the codes and their associated passages are entered into“The Ethnograph,”creating a data set for each interview group(eight,in this study). Code words and their definitions are concurrently collected in a codebook.Groups of codes that cluster around particular themes are assigned and grouped by“parent”codes.Because an idea that is encapsulated by a code may relate to more than one theme,code words are often assigned multiple parent codes.Thus,a branching and interconnected structure of codes and parents emerges from the text data,which,at any point in time,represents the state of the analysis.As information is commonly embedded in speakers’accounts of their experience rather than offered in abstract statements,transcripts can be checked for internal consistency;that is,between the opinions or explanations offered by informants,their descriptions of events, and the reflections and feelings these evoke.Ongoing discussions between members of our research group continually reviewed the types of observations arising from the data sets to assess and refine category definitions and assure content validity.The clustered codes and parents and their relationships define themes of the qualita-tive analysis.In addition,frequency of use can be counted for codes across a data set, and for important subsets(e.g.,gender),using conservative counting conventions that are designed to avoid overestimation of the weight of particular opinions.Together,these frequencies describe the relative weighting of issues in participants’collective report. As they are drawn from targeted,intentional samples,rather than from random samples, these frequencies are not subjected to tests for statistical significance.They hypothesize the strength of particular variables and their relationships that may later be tested by random sample surveys or by other means.However,thefindings in this study are un-usually strong because of near-complete participation by members of each group under study.Before presentingfindings from this study,we provide an overview of the results of our comparative analysis and describe the evolution of our analysis of the student interview data as a result of emergentfindings from analysis of the faculty interview data.Science Education DOI10.1002/sce。