Parameter identification of thermophilic anaerobic degradation of valerate

The considered mathematical model of the decomposition of valerate presents three unknown kinetic parameters, two unknown stoichiometric coefficients, and three unknown initial concentrations for biomass. Applying a structural identifiability study, we concluded that it is necessary to perform simultaneous batch experiments with differenitial conditions for estimating these parameters. Four simultaneous batch experiments were conducted at 55°C, characterized by four different initial acetate concentrations. Product inhibition of valerate degradation by acetate was considered. Practical identification was done optimizing the sum of the multiple determination coefficients for all measured state viariables and for all experiments simultaneously. The estimated values of kinetic parameters and stoichiometric coefficients were characterized by the parameter correlation matrix, the confidence interval, and the student's t-test at 9% significance level with positive results except for the saturation constant, for which more eperiments for improving its identifiability should be conducted. In this article, we discussekinetic parameter estimation methods.     

Improved synthesis of P(3HB-co-3HV-co-3HHx) terpolymers by mutant Cupriavidus necator using the PHA synthase gene of Chromobacterium sp. USM2 with high affinity towards 3HV

Unlike polyhydroxyalkanoates (PHAs) copolymers, the controlled and efficient synthesis of PHA terpolymers from triglycerides and fatty acids are yet to be established. This study demonstrates the production of P(3HB-co-3HV-co-3HHx) terpolymer with a wide range of 3HV monomer compositions from mixtures of crude palm kernel oil and 3HV precursors using a mutant Cupriavidus necator PHB⁻4 transformant harboring the PHA synthase gene (phaC) of a locally isolated Chromobacterium sp. USM2. The PHA synthase of Chromobacterium has an unusually high affinity towards 3HV monomer. P(3HB-co-3HV-co-3HHx) terpolymers with 3HV monomer composition ranging from 2 to 91 mol% were produced. Generation of 3HHx monomers was affected by the concentration and feeding time of 3HV precursor. P(3HB-co-24 mol% 3HV-co-7 mol% 3HHx) exhibited mechanical properties similar to that of common low-density polyethylene. P(3HB-co-3HV-co-3HHx) terpolymers with a wide range of 3HV molar fraction had been successfully synthesized by adding lower concentrations of 3HV precursors and using a PHA synthase with high affinity towards 3HV monomer.     

固相萃取-超高效液相色谱-串联质谱法同时测定饲料中的3种雌激素

建立了固相萃取-超高效液相色谱-串联质谱(SPE-UPLC-MS/MS)同时测定饲料(预混合、配合和浓缩饲料)中3种雌激素(17β-雌二醇、苯甲酸雌二醇和戊酸雌二醇)的检测方法。饲料样品经乙腈提取,Heaion C₁₈固相萃取柱净化后,用ACQUITY UPLC BEH C₁₈色谱柱(50 mm×2.1 mm,1.7 μm)分离,乙腈和0.1%氨水溶液作为流动相进行梯度洗脱,多反应监测(MRM)模式检测,内标法定量。结果表明,17β-雌二醇和戊酸雌二醇在10~200 μg/L、苯甲酸雌二醇在5~200 μg/L范围内具有良好线性,相关系数(r)≥0.996。17β-雌二醇、苯甲酸雌二醇和戊酸雌二醇的检出限分别为7、5和7 μg/kg。样品的平均加标回收率为96.5%~102.0%。该法前处理操作简便、分析速度快、检出限低、准确度高,可用于饲料中3种雌激素的同时检测。     

Biotransformation,spectroscopic investigation,crystal structure and electrostatic properties of 3,7α‐dihydroxyestra‐1,3,5(10)‐trien‐17‐one monohydrate studied using transferred electron‐density parameters

The biologically transformed product of estradiol valerate, namely 3,7α‐dihydroxyestra‐1,3,5(10)‐trien‐17‐one monohydrate, C₁₈H₂₂O₃·H₂O, has been investigated using UV–Vis, IR, ¹H and ¹³C NMR spectroscopic techniques, as well as by mass spectrometric analysis. Its crystal structure was determined using single‐crystal X‐ray diffraction based on data collected at 100 K. The structure was refined using the independent atom model (IAM) and the transferred electron‐density parameters from the ELMAM2 database. The structure is stabilized by a network of hydrogen bonds and van der Waals interactions. The topology of the hydrogen bonds has been analyzed by the Bader theory of `Atoms in Molecules' framework. The molecular electrostatic potential for the transferred multipolar atom model reveals an asymmetric character of the charge distribution across the molecule due to a substantial charge delocalization within the molecule. The molecular dipole moment was also calculated, which shows that the molecule has a strongly polar character.     

基于表面活性效应多壁碳纳米管修饰电极测定戊酸雌二醇

研究了戊酸雌二醇在表面活性剂存在下 ,在多壁碳纳米管修饰玻碳电极上的电化学行为 ,发现表面活性剂能显著提高戊酸雌二醇的氧化电流 基于此 ,建立了一种直接测定戊酸雌二醇的电化学方法 优化了测定参数 ,如 :介质的 pH值 ,修饰剂的用量 ,扫描速度 ,富集电位和富集时间 ,表面活性剂的种类及其浓度等 峰电流与戊酸雌二醇在 1× 10 -7～ 2 .5× 10 -5mol·L-1的浓度范围内有良好的线性关系 ,检测限为 4× 10 -8mol·L-1 1× 10 -5mol·L-1戊酸雌二醇平行测定 8次的标准偏差为 4.5 % 用多壁碳纳米管修饰电极测定了戊酸雌二醇注射液中戊酸雌二醇的含量 ,取得了满意的结果 .     

EXPERIMENTAL STUDIES ON THE LATE EFFECTS OF FEMALE SEX HORMONES

Inj. Hydroxyprogesterone Co. (EP) was injected i.m. into female Wistar rats, different strains of mice of both sex and Syrian golden hamsters with doses of 5--100 times the human contraceptive dose once or twice a month for 10--32 times. In some experiments EP was combined with whole-body 3 Gy gamma ray radiation once or twice. Results show that EP has obvious carcinogenicity and can enhance the gamma ray carcinogenicity, thereby increasing the tumor incidence or the ratio of malignant to benign turnouts. Carcinogenic mechanisms of EP have also been studied.     

Controlled biosynthesis and characterization of poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate) from mixtures of palm kernel oil and 3HV-precursors

This study investigates the biosynthesis and characterization of P(3HB-co-3HV-co-3HHx) terpolymer from mixtures of palm kernel oil and 3HV-precursors by using recombinant Cupriavidus necator PHB⁻4/pBBREE32d13. Sodium valerate and propionate have been evaluated for the generation of 3HV monomers. The feeding time of these precursors was a crucial factor that significantly affected the 3HV molar fractions, which ranged from 2 to 60 mol%. Sodium valerate was generally the better precursor in initiating the accumulation of 3HV monomers while maintaining high cell dry weight (7.9 g/L) and good PHA accumulation (79 wt%). However, the 3HHx molar fractions in the terpolymers at 72 h were consistent at about 2-7 mol%. P(3HB-co-3HV) copolymers have been known to exhibit approximately the same degree of crystallinity throughout a wide range of 3HV composition. Interestingly, in this study, terpolymers containing 58 mol% 3HB, 39 mol% 3HV and 3 mol% 3HHx showed elastomeric behavior. This study demonstrates the suitability of palm kernel oil as the main carbon source and both sodium propionate and sodium valerate as 3HV-precursors for the synthesis of novel compositions of P(3HB-co-3HV-co-3HHx) terpolymers with interesting properties.     

Stability indicating liquid chromatographic method for simultaneous quantification of betamethasone valerate and tazarotene in in vitro and ex vivo studies of complex nanoformulation

Low‐potency corticosteroid betamethasone valerate and vitamin‐A tazarotene are used in combination for effective treatment of psoriasis. There is no robust high‐performance liquid chromatography analytical technique available for simultaneous estimation of betamethasone valerate and tazarotene in conventional and nanocarriers based formulations. A simple, accurate, robust isocratic high‐performance liquid chromatography method was developed for simultaneous estimation of betamethasone valerate and tazarotene in topical pharmaceutical formulations. The developed method was validated as per the regulatory guidelines. The validated method was linear over the concentration range of 150–6000 ng/mL (r² > 0.999) at 239 nm wavelength. Limits of detection and quantification of two analytes were 50 and 150 ng/mL, respectively. The %relative standard deviation for intraday and interday precision was less than 2%. The method was also evaluated in the presence of forced degradation conditions. The developed method was successfully applied for in vitro and ex vivo drug release studies of in‐house designed nanoformulations.     

新型酰基供体用于酶法动力学拆分制备(R)-1-(2-萘基)乙胺的研究

首次成功实现了光学纯(R)-1-(2-萘基)乙胺的高效酶法动力学拆分制备,考察了脂肪酶种类、溶剂、酰基供体、底物浓度、反应温度等对拆分效果的影响,发现新型酰基供体——正戊酸对氯苯酯能够很好地抑制非酶促自催化酰胺化效应.在甲苯溶剂中,底物浓度300 mmol/L,40℃条件下,采用该供体在脂肪酶Novozym 435催化下,动力学拆分反应8 h转化率达到理论最佳值50%,eep>99%.