Search

Owing to their potential for eco-friendly matter upgrading by molecular sieving and shape-selective conversion, nanoporous materials are among the pioneers of green chemistry. The performance of their application is often controlled by diffusion, i.e. the rate of mass transfer within these materials. This mass transfer, however, is rather complex and subject to numerous influences. Unambiguous diffusion measurement has thus remained a challenge to this day with errors in the interpretation of experimental data being all too common. The present feature reports the efforts of an IUPAC initiative to overcome these limitations.

Earlier, in mice after a 30-day space flight on the Bion-M1 biosatellite, we found signs of a negative effect of weightlessness on the structure of myelinated fibers of the spinal cord tracts; these findings indicate their involvement in the pathogenesis of hypogravitational motor syndrome (HMS). In the present study, under conditions of hypogravity modeling by the hindlimb unloading, we obtained data on destructive changes in the myelinated fibers of the motor posterior corticospinal tract (tractus corticospinalis posterior), sensitive anterior spinocerebellar tract (tractus spino-cerebellaris anterior), and the gracile fascicle (fasciculus gracilis), as well as in the tibial fascicle (fasciculus tibialis) of the sciatic nerve of mice 30 days after unloading. The obtained data confirm our hypothesis on the role of disturbance in the processes of myelination of nerve fibers during the development of HMS, both during space flight and under conditions of simulating hypogravity on Earth. Morphometric analysis after a 7-day period of readaptation did not reveal signs of restoration of pathological changes in myelinated fibers that arose after 30 days of hanging. However, preventive gene therapy (administration of a gene construct providing the synthesis of recombinant vascular endothelial growth factor, glial cell line-derived neurotrophic factor, and neural cell adhesion molecule, prior to hindlimb unloading) has been shown to be effective in the preservation of myelinated fibers in projection anterior spininocerebellar tract, compared with control animals that did not receive gene therapy. The research carried out at this stage gives ground to make a preliminary conclusion about the advisability of developing methods of preventive gene therapy to prevent the development of GDS during long-term space flights.

Aim. To study the dynamics of neuromotor regulation of the contractile function of “fast” and “slow” muscles in rodents during spinal shock by spinal cord transection at the level Тh11–Тh12. Methods. The experiments were carried out on laboratory rats weighing 140–180 g. The animals were divided into two groups: “Control” (8 rats) and “Spinal shock” (6 rats). The lower leg muscles, m. soleus and m. extensor digitorum longus (m. EDL), were dissected by partially isolating without disrupting the connection with the body's circulatory system. The sciatic nerve was stimulated with single electrical impulses (10 V, 0.5 ms). Contractions of both muscles caused by electrical stimulation of the sciatic nerve before and after the injection of the substances into the femoral artery — tubocurarine (1 mM) or norepinephrine (10 mM) — were recorded in animals of both groups. After spinalization, muscle contractions were re-recorded during electrical stimulation of the sciatic nerve before and 10 minutes after the injection of tubocurarine or noradrenaline into the femoral artery in the same concentrations. Results. After spinalization of the animal, the contraction force of the muscle m. EDL fibers increased to 0.43±0.03 g (p=0.040), but the temporal parameters remained unchanged. M. soleus, on the contrary, showed a decrease in the contraction time to 0.053±0.005 s (p=0.045), and no change in the contraction force was observed under these conditions. Intra-arterial administration of norepinephrine in the control group resulted in an increase of m. soleus contractions up to 1.21±0.17 g (p=0.048), and m. EDL — up to 0.57±0.07 g (p=0.043). The administration of norepinephrine in spinalized animals caused an increase in the contraction of m. soleus up to 1.21±0.09 g (p=0.047), and m. EDL up to 0.66±0.05 g (p=0.043). The blocker of postsynaptic cholinergic receptors tubocurarine administration reduced the force of contraction of both muscle types in both control [m. soleus up to 0.39±0.03 g (p=0.039), m. EDL up to 0.11±0.02 g (p=0.042)] and spinalized [m. soleus up to 0.34±0.05 g (p=0.039), m. EDL up to 0.15±0.04 g (p=0.040)] animals. Conclusion. The data obtained demonstrate the presence of significant differences in the mechanisms of control of contractile activity in the “fast” and “slow” skeletal muscles of warm-blooded animals; the persistence of the similar effect of the basic modulators on the contraction of both muscles with such a striking reaction to spinalization highlights the contribution of neurotrophic control to the functioning of “fast” and “slow” motor units.

The composition of the intestinal microflora of rats with experimental antibiotic-associated dysbiosis and after its correction with a biological product based on lactic acid and propionic acid microorganisms was studied. The results obtained indicate the normalization of the number of microorganisms when using the suspension form of the drug and make it possible to recommend its use in clinical practice for the correction of intestinal microflora disorders in animals.

Electrophoretically homogeneous lectin with a specific activity of 100.0 U/mg protein was isolated and purified from the fungal mycelium of Fusarium solani 4. The molecular weight of the native lectin molecule (38 kDa) was determined. It was established that it consists of two identical subunits, with the molecular mass determined via PAGE-Na electrophoresis in the presence of DDS-Na equal to 19 kDa. The physicochemical properties and carbohydrate specificity of the lectin, as well as its in vitro effect on mammalian cancer cells, were studied. The results opened new prospects for the further study of lectin and its potential applications as a medical agent.

We study an actual problem of cleaning of conveyor belts from adhered finely divided materials in the process of operation of belt conveyors. The material remaining on the belts causes numerous problems for the conveyor transport. In the course of time, adhered particles fall into the subconveyor space, thus violating the normal operation of the conveyor. This also leads to rapid failures of the roller supports, excessive abrasion of the working surface of the belt, and hence, to a more rapid wear of the conveyor belt. The procedure of cleaning of the belts enables one to remove the indicated problems. At present, there are various types of available cleaning units. Each of these units has its own advantages and disadvantages. In most cases, this complicates the choice of the required unit. We estimate the efficiency of application of a discrete double-row scraper cleaner of the conveyor belt. Its application increases the degree of cleaning without damaging the surface of the belt due to the presence of a counterbalance clamping attachment.

Labeling in diffusion measurements by pulsed field gradient (PFG) NMR is based on the observation of the phase of nuclear spins acquired in a constant magnetic field with purposefully superimposed field gradients. This labeling does in no way affect microdynamics and provides information about the probability distribution of molecular displacements as a function of time. An introduction of the measuring principle is followed by a detailed description of the ranges of measurements and their limitation. Particular emphasis is given to an explanation of possible pitfalls in the measurements and the ways to circumvent them. Showcases presented for illustrating the wealth of information provided by PFG NMR include a survey on the various patterns of concentration dependence of intra-particle diffusion and examples of transport inhibition by additional transport resistances within the nanoporous particles and on their external surface. The latter information is attained by combination with the outcome of tracer exchange experiments, which are shown to become possible via a special formalism of PFG NMR data analysis. Further evidence provided by PFG NMR concerns diffusion enhancement in pore hierarchies, diffusion anisotropy and the impact of diffusion on chemical conversion in porous catalysts. A compilation of the specifics of PFG NMR and of the parallels with other measurement techniques concludes the paper.

Mining frequent itemsets in transaction databases is an important task in many applications. It becomes more challenging when dealing with a large transaction database because traditional algorithms are not scalable due to the limited main memory. In this paper, we propose a new approach for the approximately mining of frequent itemsets in a big transaction database. Our approach is suitable for mining big transaction databases since it uses the frequent itemsets from a subset of the entire database to approximate the result of the whole data, and can be implemented in a distributed environment. Our algorithm is able to efficiently produce high-accurate results, however it misses some true frequent itemsets. To address this problem and reduce the number of false negative frequent itemsets we introduce an additional parameter to the algorithm to discover most of the frequent itemsets contained in the entire data set. In this article, we show an empirical evaluation of the results of the proposed approach.

This article describes the financial fraud detection in imbalanced data. We compare various approaches for credit card fraud detection problem. On the one hand, we use homogeneous and heterogeneous Poisson process to determine the probability of predicting fraud with the various intensity parametric functions. On the other hand, we solve classification problem using machine learning algorithms and different family of ensemble methods like boostings. The results of both methods are compared. The “false positive” problem is also discussed in the article.

In this paper, the study of general toxic properties of probiotic preparation based on lactic and propionic acid microorganisms was carried out. Establishment of class of acute toxicity of studied liquid form of the drug was based on fundamental document OECD 423 "Acute Toxic Class Method" (2001). In the study of acute toxicity, the physiological state, growth rate, morbidity and safety, changes in the parenchymal organs of laboratory animals were assessed. The results of determining the acute toxicity of probiotic preparation showed that a single oral administration of it in various doses did not lead to the death of animals during the experimental period, all the main indicators of their vital activity were within the physiological norm and did not differ from the control. The condition of all groups of animals remained satisfactory, no violations of the functional activity of the digestive and urinary systems were revealed. Body temperature, respiration and heart rate of the animals were within normal limits. Shown 100% safety of animals, no toxic signs at 1000-fold increase in the dose of the liquid form of probiotic were not observed. The study of the irritating effect of the drug was carried out on the mucous membrane of the right eye of animals, applying one drop of the sample under the upper eyelid, on the anterior segment of the eye. Consideration of the possible reaction of the mucous membrane of the experimental eye, eyelid and cornea was carried out 15 minutes (fast reaction) after exposure to the drug suspension and after 24, 48 hours of observation (delayed-type hypersensitivity). Evaluation of the effect of the probiotic drug on the conjunctiva showed that the suspension of strains of microorganisms does not cause irritation, both immediately after instillation and throughout the entire study period.

In the present study, using dynamic mean field theory complemented by grand canonical molecular dynamics simulations, we investigate the extent to which the density distributions encountered during the dynamics of capillary condensation are related to those distributions at equilibrium or metastable equilibrium in a system at fixed average density (canonical ensemble). We find that the states encountered can be categorized as out of equilibrium or quasi-equilibrium based on the magnitude of the driving force for mass transfer. More specifically, in open-ended slit pores, pore filling via double bridging is an out of equilibrium process, induced by the dynamics of the system, while pore filling by single bridge formation is connected to a series of configurations that are equilibrium configurations in the canonical ensemble and that cannot be observed experimentally by a standard adsorption process, corresponding to the grand canonical ensemble. Likewise, in closed cap slits, the formation of a liquid bridge near the pore opening and its subsequent growth while the initially detached meniscus from the capped end remains immobilized are out of equilibrium processes that occur at large driving forces. On the other hand, at small driving forces, there is a continuous acceleration of the detached meniscus from the capped end, which is associated with complete reversibility in the limit of an infinitesimally small driving force.

В статье представлено исследование по изучению гепатопротекторного действия биомассы спирулины и шрота семян винограда как перспективных источников биологически активных соединений.