Catalyst-free Mannich-type reaction of 1-(N-acylamino)alkyltriphenylphosphonium salts with silyl enolates

A catalyst-free reaction of 1-(N-acylamino)alkyltriphenylphosphonium tetrafluoroborates with silyl enolates was developed to prepare β-amino carbonyl compounds. The reported method is a useful approach for the preparation of N-protected β-amino esters as well as N-protected β-amino ketones. The starting 1-(N-acylamino)alkyltriphenylphosphonium tetrafluoroborates are readily available from N-protected α-amino acids. Therefore, the presented approach can be considered a new method for the α-homologation of N-protected α-amino acids to prepare β-amino acid derivatives.     

Fingering instabilities in dewetting nanofluids

The growth of fingering patterns in dewetting nanofluids (colloidal solutions of thiol-passivated gold nanoparticles) has been followed in real time using contrast-enhanced video microscopy. The fingering instability on which we focus here arises from evaporatively driven nucleation and growth in a nanoscopically thin precursor solvent film behind the macroscopic contact line. We find that well-developed isotropic fingering structures only form for a narrow range of experimental parameters. Numerical simulations, based on a modification of the Monte Carlo approach introduced by Rabani et al. [Nature (London) 426, 271 (2003)10.1038/nature02087], reproduce the patterns we observe experimentally.     

Regiospecific Hydrogenation of Bromochalcone by Unconventional Yeast Strains

This research aimed to select yeast strains capable of the biotransformation of selected 2′-hydroxybromochalcones. Small-scale biotransformations were carried out using four substrates obtained by chemical synthesis (2′-hydroxy-2″-bromochalcone, 2′-hydroxy-3″-bromochalcone, 2′-hydroxy-4″-bromochalcone and 2′-hydroxy-5′-bromochalcone) and eight strains of non-conventional yeasts. Screening allowed for the determination of the substrate specificity of selected microorganisms and the selection of biocatalysts that carried out the hydrogenation of tested compounds in the most effective way. It was found that the position of the bromine atom has a crucial influence on the degree of substrate conversion by the tested yeast strains. As a result of the biotransformation of the 2′-hydroxybromochalcones, the corresponding 2′-hydroxybromodihydrochalcones were obtained. The products obtained belong to the group of compounds with high potential as precursors of sweet substances.     

Polyphenols Content,Antioxidant Properties and Allergenic Potency of Organic and Conventional Blue Honeysuckle Berries

Blue honeysuckle berries are a rich source of polyphenols with strong antioxidant properties. The purpose of this research was to determine the effect of organic and conventional cultivation on the polyphenols, antioxidant and allergenic potency of blue honeysuckle berry cultivars: ‘No 30’, ‘Jolanta’ and ‘Indygo’ in two growing seasons. Identification of individual polyphenols was performed using the HPLC method; the total polyphenols content and antioxidant activity were determined by spectrophotometric methods. The determination of allergic potency was tested by ELISA. In the second year of the study the total polyphenols were significantly higher in organic blue honeysuckle than in the conventional blue honeysuckle. In both growing seasons, the ‘Indygo’ cv. was characterized by the highest concentration of all bioactive compounds 3241.9 mg and 3787.2 mg per 100 g⁻¹ D.W. A strong correlation was found between the polyphenol content and the antioxidant activity for organic fruit in both years, as well as for allergenic potency. Contrary to the best bioactive properties was ‘Indigo’ cv., with the highest allergenic potency (108.9 and 139.2 ng g⁻¹ D.W.). The lowest content of specific allergens was found in the ‘No 30’ cv. Since honeysuckle is still a new cultivated plant, information about its allergenic potency is insufficient.     

Antiepileptic Drug Tiagabine Does Not Directly Target Key Cardiac Ion Channels Kv11.1, Nav1.5 and Cav1.2

Tiagabine is an antiepileptic drug used for the treatment of partial seizures in humans. Recently, this drug has been found useful in several non-epileptic conditions, including anxiety, chronic pain and sleep disorders. Since tachycardia—an impairment of cardiac rhythm due to cardiac ion channel dysfunction—is one of the most commonly reported non-neurological adverse effects of this drug, in the present paper we have undertaken pharmacological and numerical studies to assess a potential cardiovascular risk associated with the use of tiagabine. A chemical interaction of tiagabine with a model of human voltage-gated ion channels (VGICs) is described using the molecular docking method. The obtained in silico results imply that the adverse effects reported so far in the clinical cardiological of tiagabine could not be directly attributed to its interactions with VGICs. This is also confirmed by the results from the isolated organ studies (i.e., calcium entry blocking properties test) and in vivo (electrocardiogram study) assays of the present research. It was found that tachycardia and other tiagabine-induced cardiac complications are not due to a direct effect of this drug on ventricular depolarization and repolarization.     

Developments in the bulk growth of Cd1−xZnxTe for substrates

Single crystal of CdTe or dilute alloys of Cd_1−yZn_yTe (y < 0.04) and CdTe_1−zSe_z (z < 0.04) with low defect density, high purity, and large single-crystal area (>30 cm²) are required as substances for high-quality epitaxial Hg_1−xCd_xTe thin films in the infrared (IR) detector industry. Bridgman or gradient freeze is the most common technique used for commercial production of these materials because of its success in producing large-area substrates of good quality and reproducibility. For epitaxial growth of Hg_1−xZn_xTe, which has been of considerable interest in recent years as an IR detector material, the substrate of choice has been Cd_0.80Zn_0.20Te, for lattice matching with long-wavelength Hg_1−xZn_xTe epitaxial layers (x = 0.15). The primary focus of this paper is on CdZnTe, which is currently the preffered subtrate material and most widely used for both HgCdTe and HgZnTe epitaxy. This paper reviews the current status of bulk substrate technology for IR detector applications, highlighting critical issues and essential research areas for further improvement of these materials.     

The mass spectra of some selenoureas and selenothiocarbamic esters

The mass spectra of five selenoureas and two selenothiocarbamic esters are reported and discussed. Fragmentation modes are compared with those reported for the ureas, thioureas, carbamates and thiocarbamates.     

Effect of rehydration conditions on the catalytic activity of hydrotalcite-derived Mg-Al oxides in aldolization of acetone

Summary Mg-Al hydrotalcite-derived oxides with a varying Mg/Al molar ratio, ranging from 2.6 to 3.2, were rehydrated in the vapor phase at different temperatures (20-90°C). The catalytic performance of the materials obtained was studied in the aldol condensation of acetone. The initial activity of the rehydrated catalysts depended strongly on the Mg/Al molar ratio and the activation temperature. It was found that the re-arrangement of active sites, leading to the reconstruction of hydrotalcite-like phase, occurred during the catalytic test.     

The mass spectrometric fragmentation patterns of some biologically active 1,3,4-thiadiazoles

Mass spectra of some twelve derivatives of 1,3,4-thiadiazole are reported. The fragmentation scheme of the 1,3,4-thiadiazole ring is specific and indicative as to the structure. Derivatives of 5-phenyl-1,3,4-thiadiazoles show rearrangement to isothiocyanates.