Structural Characterization of 6-Halo-6-Deoxycelluloses by Direct-Dissolution Solution-State NMR Spectroscopy.

Regioselective modifications of cellulose using activated cellulose derivatives such as 6-halo-6-deoxycelluloses provide a convenient approach for developing sustainable products with properties tailored to specific applications. However, maintaining precise regiochemical control of substituent distribution in 6-halo-6-deoxycelluloses is challenging due to their insolubility in most common solvents and the resulting difficulties in precise structure elucidation by modern instrumental analytical techniques. Herein, an accessible NMR-based approach toward detailed characterization of 6-halo-6-deoxycelluloses, including the determination of the degrees of substitution at carbon 6 (DS), is presented.

Metal-Free C-H Borylation of N-Heteroarenes by Boron Trifluoride.

Organoboron compounds are essential reagents in modern C-C coupling reactions. Their synthesis via catalytic C-H borylation by main group elements is emerging as a powerful tool alternative to transition metal based catalysis. Herein, a straightforward metal-free synthesis of aryldifluoroboranes from BF and heteroarenes is reported.

Atom-Efficient Synthesis of Alkynylfluoroborates Using BF -Based Frustrated Lewis Pairs.

A sterically demanding amine, 1,2,2,6,6-pentamethylpiperidine (PMP), forms a highly reactive Lewis acid-base pair with boron trifluoride. This pair reacts with terminal acetylenes to give the products of C(sp)-H borylation, previously unknown tri- and tetraalkynylboron compounds. Trialkynylfluoroborates can serve as surrogates of alkynyltrifluoroborates for C-C coupling reactions.

[Calculation of the amount of free water molecules in aqueous solutions by means of spectral parameters from the terahertz frequency domain taking into account processes of screening].

In this paper we derive a formula to calculate the amount of free water molecules in solution. Physical values in this formula may be obtained by analyzing the spectra of aqueous solutions in the terahertz frequency range. Formula is derived on the basis of considering water polarization process in electric field.

[Calculation of the portion of free water molecules in water solutions by means of spectral analysis].

In this paper we present the results of spectral studies of water solutions and water at different temperatures. The calculation method for estimation of the portion of free water molecules is offered. The method is based on the analysis of transmissions spectra features in the terahertz region.

[On singularities of molecular relaxation in water solutions].

In this paper, we analyzed spectra of liquid water and water solutions in a frequency domain, characteristic of the collective dynamics of water molecules (from 0 to 200 cm(-1)). Particular attention is paid to the relaxation processes, one of which is observed in the terahertz region of the spectrum (approximately 5-50 cm(-1)). The physical essence of this process at the molecular level is still unclear.

[Heat shock induces simultaneous rearrangements of all known cytoskeletal filaments in normal interphase fibroblasts].

We studied the cytoskeleton heat shock response (CHSR) in normal interphase embryonic (NERF) and postnatal rat fibroblasts (NPRF) using fluorescent microscopy. Incubation of the cells at 43 degrees C resulted in reorganization of the cytoskeleton. CHSR in NERF and in NPRF were similar.

[Complete genomic sequence of rapidly replicating strain MB-7 of hepatitis a virus and its characterization in comparison with nucleotide sequences of other hepatitis A virus strains].

Complete nucleotide sequence of genomic RNA of hepatitis A virus (HAV) rapidly replicating strain MB-7 was determined. Comparison of nucleotide and deduced amino-acid sequences demonstrated the highest level of identity of MB-7 with strain HAS-15 (above 99%) and high homology with other HAV strains (HM 175/7, CR326, and GBM/HFS) used in production of anti-hepatitis A vaccines. MB-7 was classified as subgenotype IA.

[Influence of "zero" magnetic field on the growth of embryonic cells and primary embryos of mouse in vitro].

The present investigation reveals that a 250-fold screening of the geomagnetic field ("zero" geomagnetic fields, 200 nT) is a biologically active factor that adversely affects embryonic cells and the processes of early embryogenesis as a whole. In particular, the cultivation of primary embryonic fibroblasts in "zero" geomagnetic fields causes reduces the capacity for adhesion and proliferation, changes the monolayer morphology and increases cell death. In a more highly organized experimental model, two-celled mouse embryos, the exposure to the "zero" field results in an increase of plasma membrane permeability for dyes, a reorganization of the cytoskeleton because of alpha-actin redistribution, and the disturbance of the spatial orientation of blastomeres.

[Dynamics of the formation of secondary reproductive structures in Streptomyces zone-forming colonies as determined from confocal microscopy data].

The dynamics of the formation of secondary structures on the colony surface, so-called air mycelium concentric rings, was investigated by confocal microscopy and using Streptomyces zone-forming colonies as a model of a self-organizing system. The occurrence of luminescence in reproductive structures was registered, whereas in vegetative structures it was almost completely absent. It was shown that secondary reproductive structures begin to form within the thickness of substratum mycelium as branches or as an apical extension of vegetative gyphes, followed by the formation of numerous secondary branches filled with protospores.

[Experimental evaluation of the protective properties of some nonwoven materials for respiratory protection means and prospects of their use].

The protective properties of nonwoven materials (Spandbond, SMS) used to manufacture 3-5-layer medical masks, by using model physical and bacterial test aerosols, were experimentally assessed. It was shown that the more layers of the materials, the less permeable they became for test aerosols. Three-five-layer masks made from SMS at a density of 42 g/m2 were found to have higher protective properties for oil mist and fine aerosol than those made from Spandbond at a density of 25 g/m2.

[Evaluation of the protective properties of nonwoven materials for throw-away medical overalls].

The permeability of varying density felts (Spandbond, SMS, Tyvek, Sontara) for throw-away medical overalls was experimentally assessed under statistic and dynamic conditions, by using model test aerosols, including bacterial one. Their permeability was shown to decrease with the higher density of the materials under study. Laminated Span-bond contributes to an abrupt reduce in the bacterial penetration of this kind of tissues and enhances their protective properties.

[Changes in the permeability of amphibian embryo envelope for fluorochromes under the action of ultrasound].

It was determined whether high-frequency ultra sound can change the permeability of gray toad Bufo bufo and grass frog Rana temporaria under the action of high-frequency ultrasound. The changes in the permeability of embryonic envelope were assessed by using slowly penetrating fluorochromes ANS, FDA, and fluorescein. It was found that the ultrasound of 0.

[Safety research of a vaccine preparation in hepatitis A derived from the MB-7 rapidly growing strain].

A study was undertaken to prove that a vaccine drug based on the fast-growing MB-7 (MB-7 VD) of hepatitis A virus (HAV) is safe. It was established that MB-7 VD, when once injected to white outbred mice and when 4 times injected to Hartley guineas pigs, did not cause any hematological and biochemical changes in the peripheral blood or in the condition of the central nervous system of experimental animals, which shows that MB-7 VD is free of any toxic properties.

[Immunological safety and sensitizing effect of an MB-7-based vaccine against hepatitis A].

The influence of a vaccine based on the MB-7 strain of hepatitis A virus (VP-MB-7) designed at the "Vector" Center of Virology and Biotechnology was studied. VP-MB-7 was found to provoke no allergic response and to have an activating effect on the specific and non-specific responses of cell and humoral immunity similar to those evoked by hepatitis A vaccine "Hep-A-in Vac".

[A new setup for the generation and studies of mono-disperse microbiological aerosols in medical-and-biological research].

A setup for the generation and studies of mono-disperse microbiological aerosols is described in the paper. Coefficients of 3 microm aerosol deposition in the respiratory tract of mice and rats were refined by using the above setup. The probability of deposition of such particles in the trachea and lungs of mice was proven to be equal to 1.

[Spectral studies of a single cell of marine microplankton. History and perspectives].

Methods and instruments for the spectral analysis of single cells of sea microplankton under the conditions of expeditions to the Mediterranean Sea and tropical zone of the Atlantic Ocean were proposed. Special emphasis was given to the ways of adaptation of sea microplankton communities to unfavorable environment with the formation of autotrophic and heterotrophic symbiont organisms (Radiolarian, Foraminifera, etc.) having closed cycles of phosphate metabolism and variotrophic microorganisms (Cyanophyceae and Dinoflagellata class).

[Vibrational structure of absorption spectra of water in visible region].

The results of the study of the temperature dependence of water absorption spectra in the visible region and in the region of vibrational overtones are discussed.

[Autofluorescence of intact Equisetum arvense L. spores during their development].

The autofluorescence of horsetail Equisetum arvense spores excited with UV-light of 360-380 nm was studied by microspectrofluorimetry during their development from an individual cell to the formation of a multicellular thallus with the generative organs. The investigation involved the registration of the fluorescence spectra of individual intact developing cells and the measurement of the ratio of cell fluorescence intensities in the blue and red regions of the spectrum. Dry blue-fluorescing microspores showed the maxima at 460 and 530 nm and a small maximum at 680 nm.

[Dual-channel microfluorometer-photometer based on standard block assemblies and units].

The principles of construction and methods of practical realizing of double-wave microfluorometers-photometers for investigation of molecular processes in cells and cell populations are considered.

[Changes in the structural heterogeneity of surviving nerve cells].

Heterogeneity in distribution of the dry substance mass (protein) in normal and reactively altered isolated neurons has been studied in vital investigations by means of interference microscopy and microspectrophotometry. It has been demonstrated that at a reactive reconstruction neuroplasmic substances undergo rearrangement, resulting in increased heterogeneity. In peripheral juxtamembranous parts neuroplasmic colloids are divided separating the hydrated zone with a low content of protein and forming made that an increasing adhesion of the juxtamembranous proteins could result in their aggregation with protein complexes of the transmembranous ionic canals, that affects the specific electrogencic function of the neuron.