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Effectofnormalvibrationonfrictionintheatomicforcemicroscopy

experiment

SangminJeonDepartmentofChemicalEngineering,PohangUniversityofScienceandTechnology,Pohang790-784,Korea

ThomasThundatCenterforEngineeringScienceAdvancedResearch,LifeSciencesDivision,OakRidgeNationalLaboratory,OakRidge,Tennessee37831

YehudaBraimana͒

CenterforEngineeringScienceAdvancedResearch,ComputerScienceandMathematicsDivision,OakRidgeNationalLaboratory,OakRidge,Tennessee37831

͑Received18July2005;accepted19April2006;publishedonline23May2006͒

Westudiedtheeffectofperiodicnormal͑out-of-plane͒surfacevibrationsonfrictioninanatomic

forcemicroscopeexperiment.Vibrationfrequencywasvariedintherangeof1–100kHz,and

vibrationamplitudewasvariedintherangeofafewnanometers.Weobservedareductionofafew

ordersofmagnitudeinfrictioncoefficientduetotheperiodicvibrations.Frictionreductionisover

awiderangeofvibrationfrequenciesandamplitudes.Verylowvalues͑oftheorderof0.01͒of

frictioncoefficientweremeasured.Ournumericalsimulationbasedonaminimalistmodeling

qualitativelyagreeswiththeexperimentalresults.Basedonnumericalsimulations,amechanismof

frictionreductionand/orincreasewithnormalvibrationsisproposed.©2006AmericanInstituteof

Physics.͓DOI:10.1063/1.2203741͔

Howtoexperimentallymanipulateandcontrolfriction

betweenslidingsurfacesremainsaformidablechallenge.

yet.Frictioncanbeaffectedbytheapplicationofsmallper-

turbationstotheslidingsystem.1–9Implementationofade-

sirablelevelofcontrol,though,requiresaprioriknowledge

ofthestrengthandtimingoftheperturbations.Employing

surfacevibrations͑bothnormalandlateral͒tomanipulate

friction1,2,4,6,8,9isapromisingidea,however,ourabilityto

predicthowvibrationsaffectfrictionisstilllimited.Inthis

letter,westudytheeffectofsurfacevibrationsonfrictional

propertiesofsurfacesusinganatomicforcemicroscope͑AFM͒.Ourexperimentalandnumericalmodelingresults

showedasignificant͑fewordersofmagnitude͒reductionin

thefrictionforceasaresultofsurfacevibrations.Asinthe

surfaceforceapparatusexperiment,1weobservedverysmall

valuesofthefrictioncoefficientoftheorderof0.01.Both

periodicaswellasrandomvibrationsresultinasignificant

decreaseinfrictioncoefficient.

MercaptopropionicacidwaspurchasedfromAldrichand

usedwithoutanyfurtherpurification.Itwasselectedasa

boundarylubricantbecauseofitssimplestructureandhydro-

philicity.Anatomicallysmoothmicasurfacewascleaved,

anda2.5nmthicknessofchromiumanda30nmthickness

ofgoldlayersweresequentiallydepositedonit.Aself-

assembledmonolayerofmercaptopropionicacidwasformed

onafreshgoldsurfacebydippingthegold-coatedmicainto

a1mg/mlconcentrationofethanolsolutionovernight.After

beingthoroughlyrinsedwithethanolandcompletelydried

withcleannitrogen,thesubstratewasimmediatelymounted

onapiezoelectricactuator.Theamplitudeandfrequencyof

verticalvibrationbytheactuatorwerecontrolledwithadigi-

talfunctiongenerator.Forfrictionmeasurements,anAFM͑Multimode,Digital

Instrument,SantaBarbara,CA͒withaquadrantposition-

sensitivedetectorwasused.Adiodelaserisfocusedonthe

endofthecantileverandalignedtoreflectthelaserbeamto

thecenterofthedetector.Proportionalandintegralgainsofa

feedbackloopweresettolowvaluesbecausehighvalues

canexertalargeinfluenceonthelateralforcemeasurement.Scanspeedandscansizewerefixedat1.97Hzand100nm,respectively,throughoutthemeasurements.Figure1͑a͒summarizesthefrictioncoefficientsatvari-ousfrequenciesandamplitudes.Frictioncoefficient␮iscal-culatedfrom␮=␣F/L,whereFandLareafrictionforceandanormalloadinvoltage,respectively.FiscalculatedfromthedifferencebetweentraceandretracecurvesandLisfixedat2Vthroughouttheexperiment.Sincethespringconstantsofflexureandtorsionaredifferent,theratioofthespringconstants␣shouldbeconsidered.Here,␣isassignedtobe30basedonthepreviousexperimentusingthesamestructureofthesiliconcantilever.10Atalowfrequencyof1Hz,thefrictionisnotmuchaffectedbythevibration,re-gardlessoftheamplitude,becausetheverticalvibrationisslowerthanthescanningspeedofthecantilever.Thefrictionstartstodecreasesignificantlyabove100Hz,andthemini-mumfrictioncoefficientappearsat10kHz.However,thefrictioncoefficientincreasesagainabove10kHz.Thisten-dencyismoreapparentinFig.1͑b͒,wherethefrictioncoef-ficientisplottedagainstthelogarithmofthefrequencyatfixedamplitudeof4V.TheinsetofFig.1͑b͒isthesameplotasFig.1͑b͒butisplottedagainstthelinearfrequency.Sincethemechanicalresonanceoftheinstrumentplaysanimportantroleinthemeasurement,theresonancere-sponseoftheapparatuswasmeasuredtoconfirmwhethertheminimumfrictioncoefficientisrelatedtothemechanicalresonance.Alock-inamplifier͑StanfordResearchSystems,Sunnyvale,CA͒wasusedtodrivethepiezoelectricactuatora͒Electronicmail:braimany@ornl.govAPPLIEDPHYSICSLETTERS88,214102͑2006͒

0003-6951/2006/88͑21͒/214102/3/$23.00©2006AmericanInstituteofPhysics88,214102-1Downloaded 24 Feb 2011 to 162.105.25.137. Redistribution subject to AIP license or copyright; see http://apl.aip.org/about/rights_and_permissions

合集下载

异丁醇

异丁醇

异丁醇资料

异丁醇，易溶于水、乙醇和乙醚。禁配物：强酸、强氧化剂、酸酐、

异丁醇

酰基氯。可用于生产石油添加剂、抗氧剂、油漆溶剂、增塑剂、合成橡胶、合成药物，也可用来提纯分析化学试剂和高级溶剂，做增塑剂时，应用范围有限，绝不能用来制作农用塑料，因为异丁醇能引起农作物的死亡。本品的蒸汽与空气形成爆炸性混合物，爆炸极限为2.4%（体积）。无色透明具特征气味的液体，沸点108.1°C，主要用于制造醋酸异丁酯、增塑剂,或作为溶剂及有机合成原料。工业上，异丁醇是正丁醇生产的联产物，丙烯羰基合成可同时得到正丁醇及异丁醇。近年来，也用来与尿素反应制成缓释肥料。

基本信息

化学品中文名称： 异丁醇

化学品英文名称： isobutyl alcohol

中文名称2： 2-甲基丙醇

英文名称2： 2-methyl propanol

CAS No.： 78-83-1

分子式： C4H10O

分子量： 74.12

组成信息

有害物成分 含量 CAS No.

异丁醇 78-83-1 理化特性

主要成分： 纯品

外观与性状： 无色透明液体，微有戊醇味。

异丁醇

pH：

熔点(℃)： -108

沸点(℃)： 107.9

相对密度(水=1)： 0.81

相对蒸气密度(空气=1)： 2.55

饱和蒸气压(kPa)： 1.33(21.7℃)

燃烧热(kJ/mol)： 2667.7

临界温度(℃)： 265

临界压力(MPa)： 4.86

辛醇/水分配系数的对数值： 0.65/0.83

闪点(℃)： 27

引燃温度(℃)： 415

爆炸上限%(V/V)： 10.6

爆炸下限%(V/V)： 1.7

溶解性： 溶于水，易溶于醇、醚。

主要用途： 主要用作溶剂及有机合成。

其它理化性质：

Appl.Phys.Lett.89,041902(2006)

Appl.Phys.Lett.89,041902(2006)

Fabricationoftwo-dimensionalcoupledphotoniccrystalresonatorarrays

byholographiclithography

G.Q.Liang,W.D.Mao,Y.Y.Pu,H.Zou,andH.Z.Wanga͒

StateKeyLaboratoryofOptoelectronicMaterialsandTechnologies,Zhongshan(SunYat-sen)University,Guangzhou510275,People’sRepublicofChina

Z.H.ZengInstituteofMacromolecule,Zhongshan(SunYat-sen)University,Guangzhou510275,People’sRepublicofChina

͑Received18April2006;accepted27May2006;publishedonline24July2006͒

Wedemonstratetheholographicdesignandfabricationoftwo-dimensionalcoupledphotoniccrystal

resonatorarrays,whicharecomposedofhexagonalcavitiestiledtogetherinatriangularlattice.

Bandstructureanalysisrevealsthattheinversestructureofthefabricatedtemplatesupports

monopoledefectmodeinaphotonicbandgapofTMpolarization.Ourresultsshowthepractical

importanceofholographiclithographyinthefabricationofphotoniccomponentarrays.©2006

急性早幼粒细胞白血病治疗18例临床观察

急性早幼粒细胞白血病治疗18例临床观察

DOC格式论文，方便您的复制修改删减

急性早幼粒细胞白血病治疗18例临床观察

（作者:___________单位: ___________邮编: ___________）

【摘要】目的观察亚砷酸（AS2O3）,全反式维甲酸（ATRA）联合化疗方案序贯治疗成人急性早幼粒细胞白血病（APL）的疗效。方法18例APL患者，采用ATRA及亚砷酸（出现高白细胞淤积症时，给予柔红霉素）联合进行诱导，巩固及维持治疗，并定期检测PML_RARa融合基因。结果完全缓解（CR）率为87.5%，达CR中位时间为26d,并于巩固治疗期间采用AS2O3与ATRA及蒽环类药物交替进行，并于以维持治疗，总疗程为3年。目前已12例停药，13例患者每3个月检测PML—RARa融合基因均为（-），3例处于维持治疗阶段。仅2例患者未达CR因脑出血死亡。结论AS2O3与ATRA联合化疗治疗成人APL的疗效较满意。

【关键词】白血病早幼粒细胞急性成人药物疗法联合

成人急性早幼粒细胞白血病（APL）是一种特殊类型的髓系白血病，其特点是出血倾向严重，易并发弥散性血管内凝血(DIC)，导致患者早期死亡。我们用亚砷酸（AS2O3），全反式维甲酸（ATRA）DOC格式论文，方便您的复制修改删减

联合化疗治疗18例初诊APL患者，获得较满意的疗效，现报道如下。

1资料与方法

1.1临床资料

18例APL均为我科2006年9月至2009年5月收治的初治患者，男12例女6例，年龄15—74岁。临床表现均有不同程度的面色苍白，皮肤瘀斑，其中发热16例，脾大8例，肝大2例，淋巴结肿大2例，外周血HB中位值65（30-92）g/L；WBC中位值25.3（0.8-91.8）x109/L,血小板（PLT）中位值40（10-80）x109/L；骨髓细胞形态学检查：原始+早幼粒细胞0.24-0.98；诊断分型为急性非淋巴细胞性白血病（ANLL_M3）；免疫表型分析HLA_DR均为(-)；染色体核型：t（15-17）16例；融合基因PML_RARa（+）16例。

APL-期刊模板

APL-期刊模板

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This is an abstract. It gives the reader an overview of the manuscript. Abstracts are required for

all manuscripts. The Abstract should be self-contained (contain no footnotes or citations to

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interest in the article). It should be approximately 250 words. The abstract should be written as

one paragraph and should not contain displayed mathematical equations or tabular material. In this