Micro-HPLC–UV analysis of cocaine and its adulterants in illicit cocaine samples seized by Austrian police from 2012 to 2017

The worldwide consumption of illicit drugs presents a big problem in terms of health care and prosecution. In the recent years, hundreds of novel psychoactive substances came up and were traded through the Internet, but there is still a big demand for classic illicit drugs such as cocaine, heroin, cannabis, and ecstasy. Among these, cocaine particularly is frequently altered not only with excipients but also with other physiologically active substances. The purpose of this work was to estimate the trend of cocaine purity and abundance of its adulterants in samples seized by Austrian police from 2012 to 2017. A micro-HPLC method for quantification of cocaine and its most common adulterants was developed and validated using gradient elution and UV detection at four wavelengths. A total of 110 cocaine samples were analyzed. In all the samples, cocaine was present as hydrochloric salt. Caffeine, procaine, levamisole, phenacetin, lidocaine, and benzocaine were the most abundant adulterants.     

Self‐crosslinking borate anions for the production of tough UV‐cured polyelectrolyte surfaces

The first anion with four polymerizable groups has been synthesized and used to produce durable, crosslinked polyelectrolyte (PE) coatings in a single step. Sodium tetrakis(4‐vinylphenyl)borate (NaBSty₄) was produced by the reaction of BCl₃ and the Grignard of 4‐bromostyrene. The full series of borates NaBPh_xSty_4?x, x = 1?3, were also synthesized analogously by reaction of the styryl‐Grignard and PhBCl₂, Ph₂BCl, or Ph₃B. Anion exchange of the borates with tributyl 4‐vinylbenzylphosphonium chloride gave a family of organic salts developed for applications in photopolymerized coatings. The percent UV cure of the polymer films was determined by infrared spectroscopy and this relative level of curing was corroborated by differential scanning calorimetry analysis. The degree of crosslinking imparted to the polymer films by the different monomers has resulted in varied mechanical properties, which were probed by diamond tip scratch tests and nanoindentation. These clearly demonstrated that as the number of polymerizable groups increased, the film hardness increased correspondingly. The final hardness of the films exceeds those of other related systems and identifies styryl borates as viable crosslinking additives in UV curable technologies, especially in the production of durable PE films. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

A Simple Design Approach of a Fresnel Lens for Creating Uniform Light-Emitting Diode Light Distribution Patterns

Abstract

Devising an efficient method for distributing high-radiance light-emitting diode emissions onto target surfaces is a continuing challenge. Most current design methods are mathematically complex and require intricate optimizations. In this article, a simple and highly accurate geometric optics analysis is described for creating a free-form total internal reflection collimator lens and a Fresnel exit lens, which can be fabricated easily for producing a specific intensity distribution. A powerful application is the ability to create various high-efficiency and uniform illumination patterns from a standard widely used MR16 light bulb by simply attaching a Fresnel exit lens onto the face of the bulb.     

Donor-Acceptor Substituted Cyclohexasilanes: Materials with Potential Nonlinear Optical Properties

Summary.  The dipolar cyclohexasilanes 1-ferrocenyl-4-((2,2-dicyanoethenyl)-phenyl)-decamethylcyclohexasilane (1) and 1-ferrocenyl-3-((2,2-dicyanoethenyl)-phenyl)-decamethylcyclohexasilane (2) were synthesized by conventional methods and fully characterized. Electronic absorption spectroscopic studies suggest increased σ-π interactions in the cyclohexasilane derivatives when compared to their open-chained analogues. Small but noticeable electron transmission effects via the cyclohexasilanyl group can be derived from cyclic voltammetric data. Significantly increased values of the quadratic hyperpolarizabilities β in solution for 1 and 2 are shown by preliminary results of measurements using the EFISH technique. Received May 30, 2000. Accepted December 20, 2000     

肌苷和肌苷酸测定的新方法研究

采用紫外吸光光度法与高压纸电泳法联用，对次黄嘌呤类物质-肌苷及肌苷酸含量测定，试验了高压纸电泳法分离肌苷及肌苷酸的最佳条件，并对肌苷口服液等样品进行分离和测定。     

Photochemical stability of poly(vinyl alcohol) in the presence of collagen

The photochemical stability of poly(vinyl alcohol) (PVA) in the presence of 1%, 3% and 5% of collagen has been studied by Fourier Transform Infrared (FTIR) Spectroscopy, UV-vis spectroscopy, and Differential Scanning Calorimetry (DSC). PVA samples containing 1%, 3% and 5% of collagen were irradiated with UV light wavelength λ = 254 nm in air.The results have shown that PVA in the presence of 1%, 3% and 5% of collagen is less stable under UV radiation than pure PVA. A small amount of collagen in PVA enhances photooxidation in the PVA. The amount of crystallinity in PVA containing 1%, 3% and 5% of collagen decreases faster with UV irradiation time than that for pure PVA films.     

Simultaneous Determination of Vitamin B Complex Using Wavelet Neural Network

A simultaneous determination of four components of B‐group vitamin, using a novel wavelet‐based neural network (WNN), combined with correlation coefficient and standard deviation approach for wavelength selection, was reported in this work. Eleven representative wavelength points were selected from each original UV spectrum, based on correlation coefficients and standard deviations of the observed data. A family of wavelet basic functions built from Morlet wavelet was adopted to improve the transfer quality of output data and solve the problems of training difficultly involved in neural networks. The predicted results, with fitting correlation coefficients (R = 0.9998–0.9999) and rooted mean squares errors (RMS = 0.0578–0.1478), are satisfactory.