A New Procedure for the Extraction of Unconjugated Steroids from Plasma and Urine

Abstract

A procedure is described for the extraction of nanogram quantities of steroids from plasma and urine. The method involves saturation of a diluted plasma or urine sample with ammonium carbonate and extraction with an organic solvent. The application of this method to the analysis of cortisol and unconjugated estriol in plasma and to the analysis of unconjugated steroids in the urine of the newborn infant is described.     

The Application of Engineered Glucose Dehydrogenase to a Direct Electron–Transfer‐Type Continuous Glucose Monitoring System and a Compartmentless Biofuel Cell

Abstract

Continuous glucose monitoring (CGM) is expected to become an ideal way to monitor glycemic levels in diabetic patients. On the other hand, biofuel cells can be used as an alternative energy source in future implantable devices, such as implantable glucose sensors in the artificial pancreas. Glucose dehydrogenase from Acinetobacter calcoaceticus, which harbors pyrroloquinoline quinone as the prosthetic group (PQQGDH), is one of the enzymes most attractive as a glucose sensor constituent and as the anode enzyme in biofuel cells, due to its high catalytic activity and insensitivity to oxygen. However, the application of PQQGDH for these purposes is inherently limited because an electron mediator is required for the electron transfer to the electrode.

We have recently reported on the development of an engineered enzyme, quinohemoprotein glucose dehydrogenase (QH‐GDH), in which the cytochrome c domain of the quinohemoprotein ethanol dehydrogenase (QH‐EDH) was fused with PQQGDH, to enable electron transfer to the electrode in the absence of an artificial mediator. In this study, we constructed a direct electron‐transfer‐type CGM system employing QH‐GDH. This CGM system showed sufficient current response and high operational stability. Furthermore, we successfully constructed a compartmentless biofuel cell employing QH‐GDH.     

Development and Validation of Derivative Spectrophotometric Method for Determination of Rabeprazole Sodium in Pharmaceutical Formulation

Abstract

The aim of this work is to develop and validate the derivative spectrophotometric method for determination of the proton pump inhibitor rabeprazole sodium in pharmaceutical formulations. The technique was applied using water (pH 10.0) as diluent. The first‐order derivative spectra were obtained at N=5, Δλ=4.0 nm, and determinations were made at 304 nm. The method showed high specificity in the presence of formulation excipients and good linearity in the concentration range of 6.0 to 18.0 µg/mL^?1. The intra‐ and interday precision data demonstrated the method has good reproducibility [Relative Standard Deviation ((RSD)=1.0 interdays)]. Accuracy was also evaluated and results were satisfactory (mean recovery of 99.15%). The detection and quantitation limits were 0.055 and 0.17 µg/mL^?1, respectively. The method was demonstrated to be adequate for routine analysis in quality control.     

The use of HPLC for the analytical determination of diisocyanates and acid anhydrides in the air of working environments

Abstract

Measurements of airborne concentrations of (monomeric) 2,4- and 2,6-toluene diisocyanate (2,4- and 2,6- TDI), 4,4′ - diisocyanato diphenylmethane (MDI) and phthalic anhydride have been performed at 17 Danish manufactories using these compounds in the production of polyurethane foams, insulating materials, elastomers, coatings, lacquers and glues.

Diisocyanate vapours at workplaces were collected in impingers, containing a solution of 9-(N-methylaminomethyl)-anthracene (1 × 10^?4 M) in toluene. By reaction with this amine compound the diisocyanates are converted to stable urea derivatives. Phthalic anhydride particles were collected on glass fiber filters.

For separation and detection of the diisocyanate derivatives and the phthalic acid formed upon hydrolysis of its anhydride, reversed phase high performance liquid chromatography on a bonded octadecylsilyl phase using isocratic elution with acetonitrile/water and UV-monitoring at Λ = 254 nm were used. The results obtained for each manufactory are presented.     

Data Preprocessing for Chromatographic Fingerprint of Herbal Medicine with Chemometric Approaches

Abstract

Recently, the fingerprinting approach using chromatography has become one of the most potent tools for quality assessment of herbal medicine. Due to the complexity of the chromatographic fingerprint and the irreproducibility of chromatographic instruments and experimental conditions, several chemometric approaches such as variance analysis, peak alignment, correlation analysis, and pattern recognition were employed to deal with the chromatographic fingerprint in this work. To facilitate the data preprocessing, a software named Computer Aided Similarity Evaluation (CASE) was also developed. All programs of chemometric algorithms for CASE were coded in MATLAB5.3 based on Windows. Data loading, removing, cutting, smoothing, compressing, background and retention time shift correction, normalization, peak identification and matching, variation determination of common peaks/regions, similarity comparison, sample classification, and other data processes associated with the chromatographic fingerprint were investigated in this software. The case study of high pressure liquid chromatographic HPLC fingerprints of 50 Rhizoma chuanxiong samples from different sources demonstrated that the chemometric approaches investigated in this work were reliable and user friendly for data preprocessing of chromatographic fingerprints of herbal medicines for quality assessment.     

A Microbial Biosensor using Pseudomonas Putida Cells Immobilised in an Expanded Bed Reactor for the Online Monitoring of Phenolic Compounds

ABSTRACT

A cell based biosensor for phenolic substances has been developed. The set up is based on a flow injection system with an expanded bed column with immobilised Pseudomonas cells. The cells were immobilised on glass particles pretreated with poly (ethylene diamine). The system responds to a range of phenolic substances. Storage and operational stabilities are good. The expanded bed concept makes the system reliable also when treating samples with particulate matter.     

Validation of UV Spectrophotometric Method for Fexofenadine Hydrochloride in Pharmaceutical Formulations and Comparison with HPLC

Abstract

A simple, reproducible, accurate, and effective spectrophotometric method was developed and validated for the quantitation of the antihistamine fexofenadine in capsules and coated tablets. Ethanol was used as solvent and the absorbance at the wavelength of 220 nm was employed to the quantitation of the drug. The method validation was fulfilled through the evaluation of the analytical parameters of linearity, precision, accuracy, limits of detection, and quantitation and specificity. The method was linear (r=0.9999) at concentrations ranging from 8.0 to 20.0 µg ml^?1, precise (RSD intra‐day=0.29; 0.18; 0.39; RSD inter‐day=0.12 for capsules and RSD intra‐day=0.13; 0.16; 0.13; RSD inter‐day=0.13 for coated tablets), accurate (percentage recovery=99.97% for capsules and 100.51% for tablets), sensitive (limits of detection and quantitation of 0.10 and 0.29 µg ml^?1, respectively) and specific. The method was compared to a high performance liquid chromatography (HPLC) method, which was previously developed to the same drug. The results showed no significant difference between the methods in fexofenadine hydrochloride quantitation.     

基于期望视角的感知服务质量与顾客满意度区别研究

从期望出发,比较顾客视角的感知服务质量与满意度的区别。首先对期望概念进行明确界定,借鉴卡诺模型分类方法划分期望类别,基于重要性维度得到期望的三个类别:核心属性期望、重要属性期望和附加属性期望。以餐饮行业为实证研究背景,比较期望视角下的顾客满意度和感知服务质量的区别。发现核心属性期望、重要属性期望对顾客的服务质量评价影响更大,而附加属性期望对顾客的满意度评价影响更大。最后,给出企业对顾客期望、服务质量与顾客满意度的管理意义。     

考虑相互信息监督下的服务合作生产契约

知识密集型服务合作生产由于存在相互之间的知识依赖和信息粘性,双方信息管理效率影响合作激励机制的设计。从相互信息监督视角出发,综合考虑双方信息监督效率和相对重要性参数对服务合作生产契约设计的影响。结果表明,在双方信息监督效率相同情况下,相对更重要的一方拥有剩余激励是最优的;在双方信息监督效率不同时,让监督更有效且相对更重要的一方拥有剩余激励是最优的;如果监督效率优势和相对重要性优势没有集中于一方,则结果取决于两者的比较,具有更强优势的一方应该成为剩余激励索取者。双方的相对重要性和信息监督效率共同决定合作契约。     

信息与计算科学专业毕业设计的现状及改革研究

针对一般本科院校信息与计算科学专业毕业设计存在的问题,结合培养目标和专业特色,提出毕业设计改革思路.从选题、质量监控、过程管理、专业基础与内涵和指导教师队伍建设等方面实施相应的改革措施.