Effects of various anionic chiral selectors on the capillary electrophoresis separation of chiral phenethylamines and achiral neutral impurities present in illicit methamphetamine

In this study, various anionic chiral selectors were investigated for the capillary electrophoresis (CE) separation of six chiral phenethylamines and three achiral neutral impurities which are commonly identified in illicit methamphetamine. Analyses were carried out at pH 8 (high osmotic flow) with untreated capillaries using 25 mM chiral surfactant or 10 mM charged cyclodextrin. The chiral selectors included the micelle (R)-N-dodecoxycarbonylvaline (EnantioSelect (R)-Val-1) (ES) and the cyclodextrins sulfobutyl(IV)-ether-beta-cyclodextrin (SBE(IV)-beta-CD) (BSB4), SBE(VII)-beta-CD (BSB7), SBE(XII)-beta-CD (BSB 12), SBE(IV)-gamma-CD (GSB-4), SBE(VII)-gamma-CD (GSB-7), sulfated(XI)-alpha-cyclodextrin (SU(XI)-alpha-CD (AS11), SU(VII)-beta-CD (BS7), SU(XII)-beta-CD (BS12) and SU(XIII)-beta-CD (GS13). Enantiomeric and achiral selectivity strongly depends on the size of the CD, the average degree of substitution, and the type of substitution. ES exhibits good performance for the neutral solutes, but exhibits enantiomeric selectivity only for the alpha-hydroxyphenethylamines. GS13 provides the best overall enantiomeric selectivity. All fifteen solutes related to methamphetamine are simultaneously separated using BSB7.     

The vasopressin precursor is not processed in the hypothalamus of Wolfram syndrome patients with diabetes insipidus: evidence for the involvement of PC2 and 7B2

Wolfram syndrome (WS) is characterized by optic atrophy, insulin-dependent diabetes mellitus, vasopressin (VP)-sensitive diabetes insipidus, and neurosensory hearing loss. Here we report a disturbance in VP precursor processing in the supraoptic and paraventricular nuclei of WS patients. In these patients with diabetes insipidus we could hardly detect any cellular immunoreactivity for processed VP in the supraoptic and paraventricular nuclei. On the other hand, in the paraventricular nucleus a considerable number of cells immunoreactive for the VP precursor were present. In addition, the proprotein convertase PC2 and the molecular chaperone 7B2 were absent. As expression of PC2 and 7B2 was detected in the nearby nucleus basalis of Meynert of one WS patient and in the anterior lobe of the other WS patient, the absence of the two proteins in the paraventricular nucleus was not due to mutations in their genes. These results indicate that in WS patients with diabetes insipidus, not only does VP neuron loss occur in the supraoptic nucleus, but there is also a defect in VP precursor processing.     

立体车库的应用及结构设计方案研讨

针对我国的一些大中城市所出现买车容易停车难的现象,文章表述了几种常见的立体车库结构设计方案,着重展示了升降横移式、垂直升降式立体车库的应用实例,通过对巷道堆垛机式立体车库的结构特点、工作效率进行分析、比较,客观展示了双环水平转盘立体车库的结构设计优势.     

Tunable/adaptive second-order IIR notch filter

A modified second-order infinite impulse response (IIR) notch filter with constrained poles and zeros is presented to eliminate or retrieve sinusoids embedded in a broadband signal. Such a filter is ideally suited to either parallel or cascaded implementation. Two classes of problems are considered. The first is where the sinusoidal frequencies are known a priori. For this case a straightforward design procedure based on a set of design characteristic graphs is used to select tunable notch filter parameters. An interesting property of the notch filter model is that it can be converted to a line enhancer by interchanging the position of the poles and zeros. The second type of problem arises when the sinusoidal frequencies are unknown and possibly varying with time. This means that an adaptive solution is required and an important consideration is the parameter estimation accuracy. For this purpose, the paper derives the Cramer–Rao lower bound for the adaptive cascaded notch filter using a frequency-domain approach. Some simulation results are included to demonstrate the effectiveness of the proposed adaptive notch filter.     

巨亮魔晶美国总部全力支持车衣裳

正引文:自2月份于广州AAITF展会上首发以来,巨亮魔晶凭借其颠覆传统的理念引发了市场广泛关注。巨亮魔晶美国总部核心技术负责人、化学专家Alex先生3月份到访中国,则大有趁热打铁的意味。近日,受车衣裳总经理崔勋先生之邀,巨亮魔晶美国总部核心技术负责人、化学专家Alex(阿历克斯)先生到访中国,对中国市场进行调研,同时现身巨亮魔晶北京总部进行技术指导。     

PHYSICO-CHEMICAL CHANGES DURING ENZYMATIC LIQUEFACTION of MANGO PULP (cv. Keitt)

Mango pulp from Keitt variety was liquefied with 1.1 mL/kg commercial enzyme mixture preparations for 2 h at 40C. Various physico-chemical characteristics of the mango pulp at different stages of liquefaction were investigated. Apparent viscosity of pulp and serum reduced rapidly to 78% and 93% respectively, in 30 min liquefaction. No marked changes in apparent viscosity of pulp samples and percentage cell wall hydrolysis in the subsequent 60, 90 and 120 min were observed. High correlation coefficient values (R² > 0.99) of the linear regression analysis showed the feasibility of using a power law model for fitting the shear stress-shear rate data of the pulp. the enzymetreated pulp showed 83% and 84% serum yields during 30 and 120 min reaction times respectively against 52% for fresh pulp. Slight increase in TSS (°Brix), acidity, reducing and total sugars, and slight decrease in pH was found in the pulp as well as serum fractions as the incubation continued. No marked change in color (yellowness) was observed in the enzyme-treated pulp, however, the corresponding serum showed less yellowness and color saturation indicating retention of yellow pigments in the pulp fraction. Δ-3-carene was identified as major mono terpenic compound in mango pulp comprising more than 73% of the total aroma compounds. About 9% loss in the total aroma components was observed during the liquefaction process.     

EFFECT of ENZYMES ON MICROFILTRATION of APRICOT PUREE1

In pilot plant flitration tests, using a ceramic microfilter, it was shown that pectinase was effective in increasing flux at an enzyme level as low as 75 ppm and that flux increased with time during filtration. Cellulase was shown to inhibit flux when used alone or in combination with pectinase, even though it contributed to reducing viscosity of the puree. Both cellulase and pectinase were partially held back by the filter; usually more than half the pectinase was retained. This resulted in increased enzyme concentration with time in retentate. Retained enzymes might be used by continuously adding fresh puree with reduced enzyme to retentate after startup.     

Sensory Evaluation of Binding of Vanillin by Fababean Proteins

Sensory studies were conducted to estimate the perceived vanillin flavor of protein-vanillin systems that contained free vanillin and vanillin bound to fababean protein micellar mass (PMM). Nine panelists used the magnitude estimation technique to evaluate vanillin flavor by tasting. A power function was established from a series of different concentrations of vanillin solutions versus their respective sensory estimates of vanillin flavor and used to convert sensory estimates to perceived vanillin concentrations of the vanillin-PMM slurries. The perceived vanillin in vanillin-PMM systems was directly related to the free vanillin in the corresponding system as determined by HPLC, indicating that only the free vanillin contributed to the flavor. Thus, instruments can be used to predict human perception of a particular flavorant in a food system of flavor-protein interactions.     

下一代通信技术对广播电视业务发展的影响(中)

(接上期第33页) 2 下一代通信传输对广播电视业务发展的影响 2.1 下一代通信具有更高的速率、更大的容量 近年来,以数据、视频为主的业务每年在爆炸性激增,并逐步超越语音业务,成为干线链路中传送的主要信息流,这使得目前长途传输网络的业务总量迅速飙升,促使人们不断寻求新的解决方案,以进一步增加链路带宽,提高网络传输业务的能力.