The effect of S-substitution at the O6-guanine site on the structure and dynamics of a DNA oligomer containing a G:T mismatch

The effect of S-substitution on the O6 guanine site of a 13-mer DNA duplex containing a G:T mismatch is studied using molecular dynamics. The structure, dynamic evolution and hydration of the S-substituted duplex are compared with those of a normal duplex, a duplex with Ssubstitution on guanine, but no mismatch and a duplex with just a G:T mismatch. The S-substituted mismatch leads to cell death rather than repair. One suggestion is that the G:T mismatch recognition protein recognises the S-substituted mismatch (GS:T) as G:T. This leads to a cycle of futile repair ending in DNA breakage and cell death. We find that some structural features of the helix are similar for the duplex with the G:T mismatch and that with the S-substituted mismatch, but differ from the normal duplex, notably the helical twist. These differences arise from the change in the hydrogen-bonding pattern of the base pair. However a marked feature of the S-substituted G:T mismatch duplex is a very large opening. This showed considerable variability. It is suggested that this enlarged opening would lend support to an alternative model of cell death in which the mismatch protein attaches to thioguanine and activates downstream damage-response pathways. Attack on the sulphur by reactive oxygen species, also leading to cell death, would also be aided by the large, variable opening

An Investigation of Products of (n, ƒ), (n, ɣ) and (ɣ, ƒ), (ɣ, xn, p) Reactions on Samples of Uranium and Bismuth using the Phasotron and LINAС-200 Accelerators at JINR: Experiments and Calculations

The paper presents the results of physical experiments with 238U and 209Bi samples at the Nuclotron, Phasotron and LINAC-200 accelerators of the Joint Institute for Nuclear Research, with the results processed using the FLUKA, GEANT4 and MCNP programs

PEG Branched Polymer for Functionalization of Nanomaterials with Ultralong Blood Circulation

Nanomaterials have been actively pursued for biological and medical applications in recent years. Here, we report the synthesis of several new poly(ethylene glycol) grafted branched-polymers for functionalization of various nanomaterials including carbon nanotubes, gold nanoparticles (NP) and gold nanorods (NRs), affording high aqueous solubility and stability for these materials. We synthesize different surfactant polymers based upon poly-(g-glutamic acid) (gPGA) and poly(maleic anhydride-alt-1-octadecene) (PMHC18). We use the abundant free carboxylic acid groups of gPGA for attaching lipophilic species such as pyrene or phospholipid, which bind to nanomaterials via robust physisorption. Additionally, the remaining carboxylic acids on gPGA or the amine-reactive anhydrides of PMHC18 are then PEGylated, providing extended hydrophilic groups, affording polymeric amphiphiles. We show that single-walled carbon nanotubes (SWNTs), Au NPs and NRs functionalized by the polymers exhibit high stability in aqueous solutions at different pHs, at elevated temperatures and in serum. Morever, the polymer-coated SWNTs exhibit remarkably long blood circulation (t1/2 22.1 h) upon intravenous injection into mice, far exceeding the previous record of 5.4 h. The ultra-long blood circulation time suggests greatly delayed clearance of nanomaterials by the reticuloendothelial system (RES) of mice, a highly desired property for in vivo applications of nanomaterials, including imaging and drug delivery

РАЗРАБОТКА ТЕХНОЛОГИИ И НОРМАТИВНОЙ ДОКУМЕНТАЦИИ НА ИМПОРТОЗАМЕЩАЮЩИЙ ПРОДУКТ ПЕРЕРАБОТКИ БРОККОЛИ

The aim of the present investigation was development of an efficient technology for obtaining powders from fresh broccoli; determination of the possibility of using domestic production of broccoli as an import-substituting product; development of regulatory documentation for broccoli powders for the food industry. The research was carried out jointly with the representatives of the Federal Scientific cen-ter of vegetable production on an experimental basis in 2016. The domestic Tonus variety of broccoli (Federal Scientific center of vegetable production) and the Maraton F1 hybrid (France), differing in appearance, vegetative period, biochemical and physical characteristics were chosen. Technology of broccoli powder production from domestic and imported products was developed using two methods of drying convection and lyophilization. The gentle drying conditions of broccoli freeze drying compared to convective drying technology provided higher content of both vitamin C and polyphenols in the final powder. Comparative studies of organoleptic and physico-chemical properties of powders obtained from domestic and imported broccoli demonstrated close quality parameters, indicating the possibility of effective domestic broccoli utilization and import substitution. For the first time in the Russian Federation, the "Organization Standard" was developed for regulation of the quality parameters of broccoli powders intended for use in the food industry.Цель данных исследований заключалась в разработке эффективной технологии получения порошков из свежей капусты брокколи; установлении возможности использования брокколи отечественного производства как импортозаме-щающего продукта; разработке нормативной документации на порошки брокколи для использования в пищевой промыш-ленности. Исследования проводили совместно с представителями ФГБНУ ВНИИССОК на экспериментальной базе в посевной период 2016 года. К исследованиям принята капуста брокколи: отечественный сорт Тонус (селекции ФГБНУ ВНИИССОК) и гибрид Маратон F1 (производитель Франция), различающиеся по внешним признакам, продолжительности вегетации, биохимическим и физическим характеристикам. Технология порошков брокколи из сырья отечественного и импортного производств осуществлена с применением двух способов сушки – конвективной и лиофильной. Щадящие условия высушивания свежего продукта при лиофильной сушке обеспечивали повышенное содержание в конечном порошке как витамина С, так и полифенолов по сравнению с порошками конвективной сушки. Сравнительными исследованиями органолептических и физико-химических свойств порошков, полученных из сырья разного происхождения, установлены близкие показатели качества, что является обоснованием для использования отечественного сырья в качестве импортозамещающего. Впервые в Российской Федерации разработан «Стандарт организации», призванный регламентировать показатели качества порошков брокколи, предназначенных для использования в пищевой промышленности

The Magnitude and Mechanism of Charge Enhancement of CH∙∙O H-bonds

Quantum calculations find that neutral methylamines and thioethers form complexes, with N-methylacetamide (NMA) as proton acceptor, with binding energies of 2–5 kcal/mol. This interaction is magnified by a factor of 4–9, bringing the binding energy up to as much as 20 kcal/mol, when a CH3+ group is added to the proton donor. Complexes prefer trifurcated arrangements, wherein three separate methyl groups donate a proton to the O acceptor. Binding energies lessen when the systems are immersed in solvents of increasing polarity, but the ionic complexes retain their favored status even in water. The binding energy is reduced when the methyl groups are replaced by longer alkyl chains. The proton acceptor prefers to associate with those CH groups that are as close as possible to the S/N center of the formal positive charge. A single linear CH··O hydrogen bond (H-bond) is less favorable than is trifurcation with three separate methyl groups. A trifurcated arrangement with three H atoms of the same methyl group is even less favorable. Various means of analysis, including NBO, SAPT, NMR, and electron density shifts, all identify the +CH··O interaction as a true H-bond

Investigation of Terahertz Vibration–Rotation Tunneling Spectra for the Water Octamer

We report a combined theoretical and experimental study of the water octamer-h16. The calculations used the ring-polymer instanton method to compute tunnelling paths and splittings in full dimensionality. The experiments measured extensive high resolution spectra near 1.4 THz, for which isotope dilution experiments and group theoretical analysis support assignment to the octamer. Transitions appear as singlets, consistent with the instanton paths, which involve the breakage of two hydrogen-bonds and thus give tunneling splittings below experimental resolution

DEVELOPMENT OF TECHNOLOGY AND REGULATORY DOCUMENTATION ON PROCESSED BROCCOLI PRODUCT

The aim of the present investigation was development of an efficient technology for obtaining powders from fresh broccoli; determination of the possibility of using domestic production of broccoli as an import-substituting product; development of regulatory documentation for broccoli powders for the food industry. The research was carried out jointly with the representatives of the Federal Scientific cen-ter of vegetable production on an experimental basis in 2016. The domestic Tonus variety of broccoli (Federal Scientific center of vegetable production) and the Maraton F1 hybrid (France), differing in appearance, vegetative period, biochemical and physical characteristics were chosen. Technology of broccoli powder production from domestic and imported products was developed using two methods of drying convection and lyophilization. The gentle drying conditions of broccoli freeze drying compared to convective drying technology provided higher content of both vitamin C and polyphenols in the final powder. Comparative studies of organoleptic and physico-chemical properties of powders obtained from domestic and imported broccoli demonstrated close quality parameters, indicating the possibility of effective domestic broccoli utilization and import substitution. For the first time in the Russian Federation, the "Organization Standard" was developed for regulation of the quality parameters of broccoli powders intended for use in the food industry