微波消解-石墨炉原子吸收光谱法测定蔬菜中痕量钼

建立了微波消解-石墨炉原子吸收光谱法测定蔬菜样品中的痕量钼。通过密闭高压、微波消解样品来制备样品溶液,研究了不同基体改进剂及其用量对吸光度的影响;采用氘灯背景扣除,313.3 nm作为钼的测定波长,3μL 1 g·L~(-1)磷酸二氢铵为基体改进剂,灰化温度为1000℃;原子化温度为2800℃。在该实验条件下,方法的线性范围为0~200μg·L~(-1),相关系数r=0.9997,检出限为3.6μg·L~(-1),测定样品的相对偏差为0.50~2.1%,回收率为92.8%~102.4%。该法灵敏快速,准确度高,适用于蔬菜等植物样品中痕量钼的测定。     

分光光度法测定铜合金中微量钼

抗坏血酸—硫氰酸盐分光光度法较为广泛的应用于钼的测定,是灵敏度和相对稳定性较好的测定钼的一种方法。本文以铜盐作催化剂,用硫脲消除基体铜的干扰,用抗坏血酸作还原剂,使5价钼与硫氰酸盐形成橙色络合物,借此作为钼的光度法测定。此络合物的最大吸收波长为460 nm,钼的浓度0～4.0 mg/L 范围内有良好的线性关系。方法用于铜合金中钼的测定,相对标准偏差小于2%     

彩色片的加色法与减色法

加色法光的三原色是红(R)、绿(G)、蓝(B)。这三种色光以不同的比例相加,可以得到各种不同的颜色。红、绿、蓝三个色光的波长分别为单色光,彩色照片所用的色光波长范围为:R,600～700nm;G,500～600nm;B,400～500nm。人们把光的三原色混合称之为加色混合。两种色光等量混合即成为剩余原色的补色。三种色光等量混合则成为白色光。     

富士Reala彩色负片优良特性浅析

1.前言所称多层彩色片(Tripack Film)是利用感红、感绿、感蓝的照相乳剂层,分别感受红、绿、蓝三原色为光学单元的原理;经彩色显影后,发色生成青、品红、黄色三种补色组合的染料影像。这种胶片结构从发明之日开始,沿袭至今未做更动。感红照相乳荊层感受波长600～700nm;感绿照相乳剂层感受波长500～600nm;感蓝照相乳剂层感受波长400～500nm。波峰值则感红层在610nm左右;感绿层在540nm左右;感蓝层     

磷锑钼蓝分光光度法测定大米和面粉中磷

该文采用酸度为0.10 mol/L的硫酸作为介质,磷(Ⅴ)与钼酸铵发生显色反应生成淡黄色络合物,在抗坏血酸和酒石酸锑钾的还原下变成蓝色络合物。在磷锑钼蓝分光光度法的基础上,研究加入铋(Ⅲ)之后对测定磷的影响,发现铋(Ⅲ)的引入,使测定磷的灵敏度提高54.6%。体系最大吸收波长在708 nm,磷含量在0.040~0.90μg/mL范围内与吸光度呈现良好的线性关系,其线性回归方程为A=1.859C+0.079,线性相关系数r=0.999 5,其表观摩尔吸光系数ε708nm=6.19×104L/mol/cm,方法检出限为0.023μg/mL。该法可成功地测定食物大米和面粉中磷的含量。     

双波长法改进纳米TiO2光催化活性评测方法研究

研究了双波长分光光度法在光催化降解有机染料溶液中的应用;确定了纳米TiO2-亚甲基蓝混合液吸光度测定的最佳工作条件:测量波长660 nm,参比波长720 nm,TiO2含量小于150 mg/L,RSD(相对标准偏差)≤1.6%.与一般采用的离心或过滤分离的方法相比,双波长法测定的混合液中亚甲基蓝的吸光度与标准溶液的最为接近,浓度-吸光度的线性关系也较吻合,其线性相关系数r=0.9993.另外,本文还测定了几种常见染料光催化降解(纳米TiO2)的双波长法评测工作条件;对实际光催化降解反应的测试结果表明,与离心法和过滤法相比,双波长法测定快速,结果更为准确,有效的避免了实验的系统误差及偶然误差.     

苯基荧光酮分光光度法测定微量钼(Ⅵ)

研究了在表面活性剂CTMAB存在下,1.5～2.5moL/L硫酸介质中显色剂苯基荧光酮(苯芴酮)与钼(Ⅵ)的分光光度性质及反应条件,其最大吸收波长λmax=523nm,检测钼(Ⅵ)范围为0 ～20μg/25mL,符合朗伯-比尔定律,相关系数为R=0.9988.并试验了多种离子的干扰情况,建立了分光光度法测定微量钼的高灵...     

钨带灯的亮度温度-波长特性及其与结构的关系

在温度量值复现与传递以及国际比对中经常需要对亮度温度进行波长修正.探讨了钨带灯结构与亮度温度模型的关系,计算了T型钨带灯在400～1100 nm亮度温度对波长的导数,并利用实验数据进行了大波长间隔的修正验证.定性分析了不同结构钨带灯与T型钨带灯亮度温度-波长特性的差异.利用钨带灯的亮度温度-波长特性进行波长修正可减小温度量值传递的不确定度,扩展钨带灯应用的光谱范围.     

应用100％相消干扰波长的双波长信号系数光度法同时测定镁和钙

在pH10．5的NH3-NH4Cl缓冲溶液中，镁和钙均能与酸性铬蓝K（ACBK）形成暗红色配合物。应用试剂ACBK褪色对钙配合物生色产生100％相消干扰的波长542nm作为镁的测定波长以消除钙的干扰，建立了测定镁的双波长信号系数光度法。于λ^aP542nm，λ^aN602nm测得镁的信号系数，为3．776，信号摩尔吸光系数1．73×10^4L·mol^-1·cm^-1，线性范围为0．02—1．80mg·L^-1。以试剂ACBK褪色对镁配合物生色产生100％相消干扰的波长553nm作为钙的测定波长以消除镁的干扰，建立了测定钙的双波长信号系数光度法，于λ^aP498nm，λ^aN553nm测得钙的信号系数fz为2．083，信号摩尔吸光系数为1．31×10^4L·mol^-1·cm^-1，线性范围为0．03～3．00mg·L^-1，为测验方法，测定了水样中的镁和钙，回收率为96％～104％。     

原子吸收光谱法测定氧化铝中氧化锂含量

本文研究了氧化铝中氧化锂含量的测定方法。氧化铝试样于聚四氟乙烯密封熔样器中,加盐酸恒温溶解后．以空气-乙炔贫焰,于原子吸收光谱仪上．波长670．8nm处测量溶液的吸光度,测定氧化锂含量。方法有灵敏度高、选择性好、准确度高、干扰少和简便快速的优点,完全适用于氧化铝中氧化锂的测定。     

Effects of Ni2+ concentration and vacuum annealing on structure,morphology and optical properties of Ni doped ZnS nanopowders synthesized by hydrothermal method

Ni doped ZnS nanopowders were synthesized by hydrothermal method. The as-synthesized ZnS nanopowders possessed zinc blende structure with the particle sizes of ～20?nm, and they display a broad emission band from 400?nm to 700?nm centered at ～540?nm. The influence of Ni²⁺ doping and vacuum annealing on the structure, morphology and optical properties was investigated systematically. The results revealed that the emission peaks are blue shifted with Ni²⁺ doping, and the emission peaks of 0.2, 0.4, 0.6, 0.8 and 1.0?mol% Ni²⁺ doped ZnS nanopowders are centered at ～520, ～ 510, 500, 490 and 470?nm, respectively. While, the zinc blende phase transformed to wurtzite phase when annealing at 600?°C or higher, and the annealed samples exhibited three emission peaks positioned at ～490, ～547 and ～580?nm. The results indicated that the as prepared Ni²⁺-doped ZnS nanopowders have a potential application in LED as light conversion layer.     

Ion beam shaping and downsizing of nanostructures

We report a new approach for progressive and well-controlled downsizing of nanostructures below the 10?nm scale. A low energetic ion beam (Ar(+)) is used for gentle surface erosion, progressively shrinking the dimensions with ～1?nm accuracy. The method enables shaping of the nanostructure geometry and polishing of the surface. The process is clean room/high vacuum compatible being suitable for various applications. Apart from technological advantages, the method enables the study of various size phenomena on the same sample between sessions of ion beam treatment.     

碳纳米管载体改性条件对Pt纳米粒子电催化氧化性能的影响

利用紫外光照射诱导亚甲基蓝改性碳纳米管(MWCNTs), 是一种工艺简单、绿色无毒的改性催化剂碳载体的新方法。本研究以光照改性时间、改性剂(亚甲基蓝)用量和紫外光波长为主要影响因素, 系统研究了不同因素对MWCNTs改性的影响及其对催化剂催化性能的影响。利用透射电子显微镜(TEM)对不同条件下的催化剂形貌进行了表征, 采用循环伏安法(CV)和时间电流法(i-t)等电化学测试手段对催化剂在碱性介质中催化氧化甲醇的催化活性和催化稳定性分别进行了测试, 研究结果表明: 光照时间为6 h、亚甲基蓝用量为10 mg、紫外光波长采用254 nm时, MWCNTs的改性效果最佳, Pt纳米粒子在改性最佳的MWCNTs表面的负载均匀性最好, 所得催化剂的催化性能也最优, 其催化活性是商业Pt/C催化剂的2倍多, 这种改性方式为高活性、低成本燃料电池阳极催化剂的研究提供了新方法。     

Ultrasound-assisted fabrication of nanoporous CdS films

A new method for fabricating nanoporous CdS films is reported. It involves exposing the CdS solution with ultrasound waves during the process of dip coating. Indium tin oxide (ITO)-coated glass and plastic (commercial transparency) were used as substrates. In each case three different precursors were used for dip coating. The precursors used were CdCl2 and thiourea in one case and CdS nanoparticles prepared by sonochemical and microwave-assisted methods in the other two cases. X-ray diffraction studies performed on these powders show a phase corresponding to cubic CdS. The Field Emission Scanning Electron Microscopy (FE-SEM) images of the films on plastic showed uniform pores with a diameter of 80 nm for all three methods. Optical absorption measurements indicated a blue shift and multiple peaks in the absorption curve. The FE-SEM observations of the films on an ITO/glass substrate indicated a crystalline film with voids. The UV-vis absorption results indicated a blue shift in the absorption with an absorption edge at 435, 380, and 365 nm for CdS films made by solution growth, sonochemical, and microwave routes, respectively. The magnitude of the absorption is dependent on film thickness, and the observed blue shift in the absorption can be explained on the basis of quantum confinement effects.     

钒铁中磷的分析方法改进

本文针对现有国标分析方法 GB/T 8704.7-2009钼蓝光度法测定钒铁中的磷含量方法存在操作繁琐、流程长、重现性差,准确度低、成本较高等问题进行了改进。通过采用硫酸加硝酸溶样,用亚硫酸钠还原钒为统一的4价,采用对应试液作参比消除钒的干扰等手段,使钒铁中磷的含量的测定方法变得操作简便、快速、准确、成本下降。     

辉光放电发射光谱法测定纯净钢中磷含量的不确定度评定

磷元素的激发波长短,纯净钢中磷元素的百分含量低,准确测量存在一定难度。通过辉光放电发射光谱法对纯净钢中磷元素含量进行测定。对测定过程中分析不确定因子进行相应不确定度的评定和计算,找出影响结果最大的不确定因素。评定结果表明,辉光放电发射光谱法测定纯净钢中磷元素含量能满足分析准确度的要求,可应用于中低合金钢中低含量磷元素的快速定量分析。     

Measuring the Prong Velocity of Quartz Tuning Forks Used to Probe Quantum Fluids

Recently, quartz tuning forks have been used to probe the dynamics of quantum fluids. For many of these measurements it is important to know the velocity amplitude of the tips of the vibrating fork prongs. We have used different techniques to establish, with an accuracy of a few percent, the relationship between the electrical and mechanical properties of several commercial quartz tuning forks with fundamental resonant frequency ～32 kHz. The velocity is usually inferred from an electro-mechanical calibration that models a quartz prong as a clamped, rectangular cantilever beam. We have tested the accuracy of this calibration using three methods: measurement of the amplitude at which the fork prongs touch each other; direct optical measurement of the moving fork prongs using strobe microscopy; and a Michelson interferometry technique operating with a 670 nm laser. All three methods yield consistent results. The velocity so determined is found to be 10% lower than that of the standard electro-mechanical calibration.     

Bi_2MoO_6空心球的水热沉淀法制备及其光催化性能

以葡萄糖为前躯体,采用水热法制备胶体碳球,以其为模板通过水热沉淀法制备C/Bi2MoO6核壳结构,然后在350℃空气中煅烧,获得了具有良好光催化性能的Bi2MoO6空心球.通过SEM、XRD、FT-IR和BET等测试方法对该催化剂进行了表征;并对其形成机理及反应过程进行了初步探讨,以亚甲基蓝作为被降解物质,研究了其光催化活性。结果表明,Bi2MoO6空心球是由纳米晶粒组成的,壁厚约为30～50nm,平均直径约为0.6～0.8μm,采用胶体碳球作模板时制得的Bi2MoO6空心球比表面积为11.315m2/g,而直接合成的粉体比表面积为3.378m2/g。在黑管灯照射下,2.5h亚甲基蓝的降解率达到了91.95%。     

稀土乙酸8-羟基喹啉三元配合物/羟基磷灰石的纳米有机/无机主客体组装复合抗菌生物材料

采用湿法原位合成了Tb、Y、Gd 3种稀土乙酸8-羟基喹啉三元配合物与羟基磷灰石的纳米有机/无机主客体组装复合材料。通过扫描电子显微镜、X射线粉末衍射、红外光谱对样品进行结构分析测定;采用最低抑菌浓度(MIC)和最低杀菌浓度(MBC)实验来检测其抗菌能力。结果表明,  3种复合材料纳米晶平均粒径为50～60 nm,皆对金黄葡萄球菌和大肠杆菌具有较高的抗菌作用,并对金黄葡萄球菌的抑制作用强于大肠杆菌。经过对3种复合材料抗菌作用的比较得出抗菌能力的次序为：  Tb-HQ/HAP < Y-HQ/HAP < Gd-HQ/HAP。     

Method to test rotationally asymmetric surface deviation with high accuracy

We have proposed a new absolute method to test rotationally asymmetric surface deviation. Relying on the high accuracy of Zernike polynomial fitting with least-squares algorithm for the low-frequency component and preserving the high-frequency component with the averaging method, the new method can guarantee the high accuracy of the measurement result with fewer rotational measurements compared to the traditional multiangle averaging method. It realizes a balance between the accuracy and efficiency of the measurements. It has been verified by experiments; the root mean square (rms) of residual figure between the two methods is ～0.6 nm. Meanwhile, the new method can suppress environmental noise introduced in measurement results well.