Spectrophotometric Methods for Simultaneous Determination of Amlodipine Besylate and Atenolol in Their Tablet Dosage Form

Three simple, specific, accurate and precise spectrophotometric methods are developed for simultaneous determination of amlodipine besylate (AM) and atenolol (AT) in tablets. The first method is dual wavelength spectrophotometry (DW). The second method is ratio subtraction (RS) which depends on subtraction of the plateau values from the ratio spectrum, coupled to first derivative of ratio spectra (1DD). The third method applies bivariate calibration method using 210 and 225 nm as an optimum pair of wavelength for amlodipine and atenolol. The calibration curves are linear over the concentration range of 4～40 μg·mL-1 for both drugs. The specificity of the developed methods is investigated by analyzing laboratory prepared mixtures of the two drugs and their combined dosage form. The two methods are validated as per ICH guidelines and can be applied for routine quality control testing.     

氯磺酚偶氮罗丹宁分光光度法测定天然水中痕量铜(Ⅱ)

在pH5.56的醋酸盐缓冲溶液中,Cu(Ⅱ)和氯磺酚偶氮罗丹宁(SCPA)生成二元配合物Cu(SCPA)2,利用光谱修正技术表征配合物的分子结构。选择吸收光谱峰谷波长530nm和418nm为工作波长,测定显色溶液及空白溶液的吸光度A530nm,A418nm及A5030nm,A4018nm。计算光吸收比差值(ΔAr)。当Cu(Ⅱ)浓度在0.200μg/mL以内与ΔAr值之间呈线性关系,方法检出限为2ng/mL,有利于直接监测天然水。本实验已测定了黄浦江、长江、太湖水样中的痕量Cu(Ⅱ),结果与电感耦合等离子体-发射光谱法的测定结果相符,方法回收率在97.0%—103.5%之间。     

基于四波段图像融合的彩色夜视方法研究

为了在低照度条件下获取目标的彩色图像,提高夜间对目标的识别能力,提出了基于四波段图像融合的彩色夜视方法.采用F-P滤光片设计出了透射中心在三基色光中心波长及近红外波段的四波段滤光片,在各个透射区域的平均透射率均达90%以上;将四波段滤光片设计成圆形滤色轮结构,用分光计测得了各波段滤光片的光谱透射性;对加入滤光片后的系统信噪比进行了分析和计算,分析结果表明加入滤光片不会引入噪声,计算结果表明加入蓝色、绿色、红色和近红外波段滤光片的成像系统的信噪比分别是原来单色微光夜视系统信噪比的19.59%、38.45%、47.28%和46.70%.借助国产超二代像增强器在微光实验室进行了四波段图像采集及彩色图像融合实验,实验时光照度分别为1×10~(-3)lx和1×10~(-1)lx,对获取的图像质量进行了评价.结果表明:在照度为1×10~(-3)lx时,融合的彩色图像在均值、方差和熵这三项指标上均优于过滤后的蓝色和绿色的单色图像,且由于彩色图像中利用了近红外图像进行增强,使得彩色图像亮度更高,颜色分辨性更好;在照度为1×10~(-1)lx时,融合后的彩色图像的信息熵比红、绿、蓝三种基色图像的大,彩色图像携带的信息量更大.本文的研究对彩色夜视成像系统的设计和研发具有借鉴和指导意义.     

基于GOSAT卫星数据的大气甲烷反演误差分析及校正

大气甲烷(CH₄)高精度反演受到多种因素的影响,其中地表特征和大气状态的不确定性是重要的影响因素,如地表反射率、温度、湿度和压力廓线。地表反射率受到诸多因素的影响,难以获得精确的数据,会给反演结果带来较大误差。温度、湿度和压力廓线的不确定性亦是反演误差的重要来源,由此产生的系统误差难以避免,单独利用CH₄吸收带进行反演难以消除此种误差。针对各种参数不确定性的影响,本文提出比值光谱法和CO₂吸收带校正法进行校正。比值光谱法通过将绝对辐亮度谱转化为比值光谱,抑制地表反射率在反演过程中的作用。CO₂吸收带校正法利用CO₂ 1.61 μm吸收带,将CH₄柱含量转化为CH₄体积混合比,校正温度、湿度和压力廓线不确定性引起的系统误差。通过将两种校正方法结合,可同时抑制地表反射率和温度、湿度、压力廓线不确定性产生的影响,减小反演误差。利用温室气体观测卫星(GOSAT)的观测数据进行大气CH₄反演,采用比值光谱法和CO₂吸收带校正上述误差,结果显示校正后的CH₄体积混合比与GOSAT-Level2产品相当接近,反演精度可达-0.24%,反演结果较为稳健可靠。研究表明,比值光谱法和CO₂吸收带校正法可有效校正地表特征和大气状态参数不确定性引起的误差,提高大气CH₄反演精度。     

XRD法测定沸石分子筛中硅铝比

用X射线衍射外推函数法测定NaY超稳分子筛的晶胞参数，用^29Si、^27Al固体NMR方法测定分子筛骨架中的硅铝比，提出了NaY超稳分子筛硅铝比与晶胞参数关联的经验公式。通过测定分子筛的晶胞参数即可得到NaY超稳分子筛的硅铝比。该方法测得的NaY超稳分子筛硅铝比，比通常采用的化学分析方法省时、简便、重复性好。     

长相依序列均值变点检测

研究了长相依序列均值变点检测问题.首先给出变点检验的Ratio统计量其次分别推导了原假设和备择假设下统计量的极限分布,最后用蒙特卡洛方法模拟出检验的临界值,并通过数值模拟和实例分析说明方法的有效性.     

Worst-case analysis of greedy algorithms for the subset-sum problem

Given a set ofn positive integers and another positive integerW, the Subset-Sum Problem is to find that subset whose sum is closest to, without exceeding,W. We present a polynomial approximation scheme for this problem and prove that its worst-case performance dominates that of Johnson's well-known scheme. Research supported by Ministero Pubblica Istruzion, Italy.     

F34—Ⅰ型深部X射线治疗机固定照射野间照射量率的比值确定

测量了１２部Ｆ３４－Ⅰ型深部 Ｘ射线治疗机的照射量率，确定了固定照射野在 １５ × １０、１０ × ８、８ × ６、６ × ４单位ｃｍ×ｃｍ）情况下的照射量率比值：在空气介质中，源皮距为３０ｃｍ时，分别为１．０１５、１．０００、０．９７６、０．９５１以及源皮距为４０ｃｍ时，分别为１．０２６、１．０００、０．９７２、０．９４１；在水模体介质中，源皮距４０ｃｍ时，分别为１．１３６、１．０００、０．８７３、０．７３４。利用这些比值，可以快速准确计算出实际照射量率，为治疗恶性肿瘤提供准确可靠的剂量率值。     

Natural convection of hybrid nanofluid heat transport and entropy generation in cavity by using Lattice Boltzmann Method

A mesoscopic study of natural convection due to MWCNT-Fe₃O₄/Water hybrid nanofluid is conducted utilizing the Lattice Boltzmann Method. The test fluid is filled in a differentially heated rectangular enclosure. Effects of aspect ratio in the range of 0.5–2.0, Rayleigh number varying from 10³ to 10⁵ and nanocomposite volume fraction on heat and fluid flow characteristics and entropy generation have been illustrated. It is observed that the mean Nusselt number rises with the increase in Rayleigh number, while it falls as the aspect ratio increases. However, the mean Nusselt number enhances with the increase in MWCNT-Fe₃O₄ volume fraction up to 0.001. On further increasing the volume fraction, the mean Nusselt number shows either no significant rise or deterioration for the case of MWCNT-Fe₃O₄ nanocomposite. The dimensionless entropy generation number rises with the increase in the Rayleigh number. However, it falls with an increase in aspect ratio and dimensionless temperature difference. Interestingly in the case of increasing nanoparticle loading fraction, entropy generation number augments first, attains a maximum at 0.001 ?vol fraction of nanocomposite, and then it decreases. Nevertheless, at the low Rayleigh number, it keeps on rising with an increase in nanocomposite volume fraction. The best thermal performance is obtained for the cavity of 0.5 aspect ratio. A correlation for the mean Nusselt number is proposed.