Resolution of the Embedded Chromatographic Peaks by Modified Orthogonal Projection Resolution and Entropy Maximization Method

ABSTRACT

The embedded chromatographic peaks usually can not be completely resolved by conventional multivariate resolution methods. The resolution condition of a certain component in two-way data is first reviewed. A modified orthogonal projection resolution (OPR) algorithm and new entropy maximization (EM) method are then proposed to resolve embedded chromatographic peaks in this paper. The modified OPR algorithm performs more precisely than conventional orthogonal projection resolution algorithm in resolving the chromatography of minor peak. The entropy criterion defined on the differential chromatography could obtain an approximate solution in resolution of the major chromatographic peak. Simulated and real data show that the modified OPR and entropy maximization (EM) methods perform well in solving the embedded problem.     

Voltammetric Determination of Allura Red AC onto Carbone-paste Electrode Modified by Silica with Embedded Cetylpyridinium Chloride

In current study the carbon-paste electrode modified by silica with embedded cetylpyridinium chloride for determination of Allura Red AC have been developed. The optimal conditions were determined to be for the square-wave voltammetric quantification: pH=2, E_ads=300 mV, t_ads=300 s, amplitude – 40 mV, frequency – 25 Hz and potential scan rate is 250 mV sec⁻¹. The calibration plot has linearity in the concentration ranges 0.04–0.2 μM and 0.2–1.00 μM. The LOD and LOQ are equal to 0.005 μM and 0.015 μM respectively. The crafted sensor has been applied successfully to model solutions and in jelly candies analysis with RSD no more than 10 %.     

Numerical investigation of microchannel geometry for effective on-chip biofluid delivery by AC electrothermal effect

Although there exist tremendous needs for on-chip biofluid delivery, research in this field has yielded limited numbers of devices for real-world applications. One challenge is the difficulty for micropumps to meet the requirements of being low cost to fabricate, easy to integrate and effective for intended applications at the same time. This research focuses on AC electrothermal (ACET) micropumps based on planar interdigitated electrodes, due to their practicality in fabrication and operation, and compatibility with biochemical fluids. Our prior work has optimized the design of electrode dimensions for a fixed microchannel design. This work finds that microchannel dimensions can also affect ACET micropumps significantly, with respect to flow rate and electric impedance loading. This work first considers the constraints arising from impedance loading by ACET micropumps on power supplies, then the investigation describes several key parameters (threshold height, saturation thickness), to arrive at an appropriate microchannel geometry for the effective delivery of biofluids. The optimized microchannel is expected to incorporate well into a multifunctional lab-chip system to transport biofluids efficiently.     

利用模式搜索法求取新的温度积分近似式

利用模式搜索法求取了一个新的温度积分近似式,给出了相应的估算动力学参数的方程。新的温度积分近似式根据数值计算结果得到,可靠性高。讨论了新的近似式计算值与温度积分数值积分结果的偏差。与其它近似式相比,新的温度积分近似式的表达式简单,精确度更高,非常适合非等温过程的动力学参数的计算。     

温度补偿法解决二元气液平衡系统相图绘制实验中的分馏效应

通过改装二元气液平衡系统相图绘制实验的装置,同时测定了环己烷-乙醇气液系统建立平衡时的沸点和露点温度,绘制并对比未保温、保温和温度补偿条件下的环己烷-乙醇气液相图。研究发现,由于分馏效应的存在,未保温和简易保温情况下,测得的溶液的沸点与露点两者温度均存在较大的差异,利用沸点温度绘制的气相线存在严重失真;对系统进行了温度补偿后根据沸点和露点温度绘制的两条气相线能吻合较好,即气相分馏效应得到了解决。     

Folding and assembly of fibroin driven by an AC electric field: effects on film properties

Silk fibroin from Bombyx mori is a high-molecular-weight protein, largely employed in the biomaterials field. Several parameters can affect the folding and assembly of fibroin heavy and light chains. The present work has shown that anisotropic and water-stable films are produced when fibroin solution is cast under an alternating electric field (AC). The treatment can affect the mechanical, thermal and surface properties of fibroin films. These effects have been related to the alignment of molecular dipoles and the formation of oriented supramolecular assemblies. Cell response is affected by this novel processing: MRC5 fibroblasts, cultured on anisotropic fibroin films, preferentially spread parallel to the field direction 6 h after seeding. [Figure: see text].     

不同温度模式下保留值关联的统一方法

提出了一种不同温度模式下保留值关联的统一方法,能够根据两个或多个任意温度模式下的保留数据预测其它温度条件下的保留值;作者已经把这个方法应用于自建的保留指数数据库软件中。     

交流碳弧法合成碳包碳化铁纳米晶

采用交流碳弧法高效合成碳包碳化铁纳米晶磁性微粉,磁性微粉产率达90%以上.用热重分析法(TG)测得磁性微粉中Fe的质量分数为17.5%.X射线衍射(XRD)分析结果表明,在碳包碳化铁微粉中存在Fe₃C和Fe₅C₂两种结构形式,不含纯Fe晶粒,碳层结构与石墨相似.在透射电镜(TEM)下观察了纳米晶的形貌和粒径分布,碳化铁纳米晶尺寸分布在3～10nm,并呈颗粒状分散在碳层中,碳层为巴基管和巴基葱的堆积体,形状各异,尺寸分布在几十纳米到几微米之间.讨论了碳包碳化铁纳米晶的形成机理.测定了磁性微粉的磁滞回线,其饱和磁感应强度Bs,剩磁Br和矫顽力Hc分别为2.6×10^-2T,2.5×10^-3T和5.52kA/m.     

Development and validation of an at-line fast and non-destructive Raman spectroscopic method for the quantification of multiple components in liquid detergent compositions

Implementation of process analytical technology (PAT) tools in the manufacturing process of liquid detergent compositions should allow fast and non-destructive evaluation of the product quality. The aim of this study was to develop and validate a rapid method for quantifying the chemical compounds of five washing liquid precursors. Raman spectroscopy was applied in combination with a two-step multivariate modeling procedure. In first instance, a SIMCA (Soft Independent Modeling of Class Analogy) model was developed and validated, allowing the distinction between the different laundry detergents. Once the product was correctly identified, it was aimed at predicting the concentration of its individual components using partial least squares (PLS) models. Raman spectra were collected at-line with a total acquisition time of 20 s, using a non-contact fiber-optic probe.     

采用交流阻抗法对质子交换膜燃料电池(PEMFC)电化学行为的研究

通过对PEMFC运行于不同状态下的交流阻抗分析,提出其等效电路可用LR₁[QR₂]表示.对各参数模拟表明,随放电电位升高感抗L下降,而系统电阻R₁和电荷转移阻抗R₂均呈上升趋势,改进催化层结构设计及在大电流运行时加大排水量有利于减小电池内部感抗;加湿温度上升有利于降低R₁和R₂,但低放电电位下R₂的偏离程度较大,电池内阻是LR₁[QR₂]的综合结果,在高放电电位时,随加湿温度上升内阻下降,低放电电位时内阻上升的原因在于水抑制了反应气体到达催化剂表面及电荷内部转移的过程,使电池内部趋向于电容状态.LR₁[QR₂]微观分析和宏观现象得到较好的统一,高放电电位时表现尤为明显.     

镧(Ⅲ)-氨基酸配合物的温度滴定量热法研究

稀土配合物因其特有的性质而日益受到人们的重视 [1] .对于稀土与氨基酸配合物的已有研究 [2 ,3] ,但尚未见到关于镧 ( )与不同种氨基酸配合反应的较系统的报道 .文献 [2 ,3]大多采用 p H电位法或其它非热化学方法 ,且大多只得到反应的平衡常数 ,而用滴定量热法直接测定其配合常数和反应焓变的研究尚未见报道 .用滴定热量法可同时测定配合反应的焓变和熵变 [4 ] ,而且在滴定量热过程中 ,反应体系基本上是一封闭体系 ,除了对体系的温度进行监测外 ,对反应体系没有其它任何干扰 ,因而可以减少外界因素的影响 ,从而减少测定的误差 .本文用滴…     

在掌上实验室探究酒精灯火焰温度——得出不同的结论

本文介绍在掌上实验室进行的酒精灯3层火焰温度的探究实验,探讨酒精灯3层火焰温度的大小及其关系。     

内标法在ICP—AES中的应用研究：Ⅱ,应用内标法校正操作参数的变化

本文较系统地研究了ＩＣＰ－ＡＥＳ中可能产生的非随机变化的参数等条件变化时内标元素的选择规则。实验结果表明，在正向功率，载气压力和观察高度变化情况下，分析元素与内标元素的配分函数的匹配最为重要。当分析元素与内标元素的能级分布相似时，可校正操作条件变化对分析准确度的影响。     

前驱体配料温度对水热法制备LiFePO4的影响

研究了配料温度对水热法制备磷酸铁锂的影响.通过X射线衍射（XRD）、扫描电镜（SEM）、循环伏安（CV）以及元素分析等手段分析了不同温度下制备的前驱体和最终的LiFePO₄样品,其结果表明配料温度对磷酸铁锂前驱体颜色和特性有明显影响.通过仔细控制该温度可以制得高纯Li₃PO₄中间体并抑制前驱体中Fe（OH）₃的形成.有利于进一步获得结晶良好不含Fe³⁺的LiFePO₄样品,显著提高了LiFePO₄材料的放电比容量.当配料温度为30℃时获得的样品,0.1C倍率下放电比容量达到156 mAh·g^-1,0.5C倍率下放电比容量为151 mAh·g^-1,10C倍率下放电比容量为127 mAh·g^-1,循环20次容量保持率达99%.     

迎头色谱程序升温脱附快速测定吸附热新方法

在Ｐｏｌａｎｙｉ吸附势理论基础上，结合程序升温脱附曲线的测定，建立了一个快速测定吸附热的新方法，详细讨论了该方法的原理，通过微机采样和数据处理，测定一条吸附热与覆盖度的曲线仅需１ｈ左右。     

一步法制备纳米铂/石墨烯及电催化甲醇的交流阻抗和扩散系数测定

采用绿色还原剂抗坏血酸,一步法制备纳米铂/石墨烯。对其进行X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)形貌结构表征,铂纳米粒子均匀分散于纳米石墨烯片层褶皱间,有效减少了团聚现象。运用循环伏安法(CV)和计时电流法(CA)研究纳米铂/石墨烯对甲醇电催化氧化活性和稳定性,通过交流阻抗(EIS)定量测定,发现铂/石墨烯比铂具有更优异的电荷传输性能,电荷转移阻抗下降了34.8%。计时电量法(CC)测定得到甲醇在铂/石墨烯电极的表面扩散系数为1.42×10~(-9) cm~2·s~(-1)。与铂纳米粒子相比,纳米铂/石墨烯对甲醇电催化氧化具有更高的活性和稳定性,显著提高电极催化活性表面积和电荷传输及转移性能。     

最小二乘法计算苯、噻吩和正辛烷在NaY上程序升温脱附活化能

采用程序升温脱附(TPD)技术测定了苯、噻吩和正辛烷在NaY上以不同升温速率升温时的TPD谱图. 利用TPD谱图的峰形和其微分曲线判断了程序升温脱附过程中的脱附级数. 提出了一种利用最小二乘法计算吸附剂/催化剂的脱附活化能及其动力学参数的方法. 以这些TPD谱图为基础, 分别采用传统TPD计算模型、最小二乘法以及一阶微分曲线法计算了苯、噻吩和正辛烷在NaY上的脱附活化能和动力学参数. 结果表明, 最小二乘法对在不同线性升温速率时的程序升温脱附活化能的计算结果是一致的.     

High Temperature Corrosion Resistance of Coatings Deposited by Hvof for Application in Steam Turbines

The geothermal steam turbines are exposed to mechanisms of corrosion/erosion that weakens its components and reduces their useful life. Due to this problem work has been done in application and characterization of coating in solid state by means of the technique of high-velocity Oxygen Fuel (HVOF), evaluating the corrosion rate (V_corr) at high temperature of MCrAlY and Diamalloy 4006 coatings deposited on stainless steel SS304. Test was performance in an Autoclave at 170 ⁰C using a modified geothermal fluid as electrolyte. Open circuit potential was monitoring during 24 hours until the system reached the equilibrium. After that, Polarization and Impedance Spectroscopy techniques were used to evaluate the specimens. For microstructure characterization; X–ray Diffraction (XRD), electron sweep microscope (SEM) and Optical microscope were applied. Results show that both coatings (Diamalloy 4006 and MCrAlY), have low current density compare with the substrate, which is an indicative of a lower corrosion rate due to the passive behavior of the species deposited on the Surface of the coating.     

Temperature optimization for improved determination of phosphatidylserine species by micro liquid chromatography with electrospray tandem mass spectrometric detection

A sensitive method for determination of disaturated phosphatidylserine species in the presence of their monounsaturated analogs has been developed, using micro liquid chromatography coupled to electrospray ionization tandem mass spectrometry. The hydrophobic nature of the phosphatidylserine species required a combination of low-eluting sample solvents and sub-ambient temperatures in order to focus large sample volumes up to 20 microL. The samples were dissolved in 2-propanol:hexane:water (20:10:4, v/v/v) prior to 1:9 dilution with ammonium formate buffer:2-propanol:tetrahydrofuran (30:55:15, v/v/v) and final 1:4 dilution with ammonium formate buffer (10 mM):2-propanol: tetrahydrofuran (55:37.5:7.5, v/v/v). The analytical column was a 0.5 x 150 mm stainless steel column packed with 5 microm C30 particles, while the mobile phase contained ammonium formate buffer (10 mM): 2-propanol:tetrahydrofuran (30:55:15, v/v/v). A temperature program from 5 degrees C (hold for 3 minutes) to 75 degrees C at 8 K/min provided separation of the disaturated phosphatidylserine species from their monounsaturated analogs, making available a sensitive determination of the isobaric species. The mass limit of detection for dipalmitoyl phosphatidylserine was 100 pg, corresponding to a concentration limit of detection of 5 pg/microL when using an injection volume of 20 microL. This is an improvement by a factor of 20 as compared to previously reported numbers obtained with conventional LC columns. The within-assay precision of dipalmitoyl phosphatidylserine was 11.9% RSD (n = 3), while the retention time precision was 4.1% RSD (n = 6).