Identification of the Mechanism of Synthesis of SDRL Rubber

Modelling and identification of the synthesis of SDRL rubber in the presence of toluene and modifier was carried out. The mechanism of the polymerization of butadiene on the lithium catalytic system. One of the most characteristic differences between the processes of ionic, in particular, anionic, polymerization and radical polymerization is that even when using initiators that seem to be individual, several forms of active centres, that differ in their reactivity, can simultaneously be present in systems.

Mathematical modelling of thermal microexplosion in a catalyst granule with point sources of heat release

A mathematical model of heat and mass transfer in a spherical catalyst granule is proposed. Exothermic synthesis reactions are carried out on point active centres located inside a porous ceramic granule. From the surface of the granule the heat of catalytic reactions is removed into liquid synthesis products. The rate of a chemical reaction is modelled by a modified Arrhenius law. In contrast to the homogeneous model of a catalytic granule methods for calculating heat transfer processes in a system of point, active centres do not develop. An iterative procedure is suggested to calculate the unknown temperature and concentration of the reagent at the active centre. It is shown that the temperature of the active centres is significantly higher than in the volume of the granule. The results of modelling a thermal explosion with increasing granule size and reactor temperature are presented.

Study on efficiency of corrosion inhibitors based on derivatives of isothiuronic salts

Metals play a pivotal role in industry; their use constantly grows. It is virtually impossible to find an industrial field without the use of metals and their alloys. However, owing to the quality degradation of metal during the operational process, corrosion appears not only on its surface but also under a coating, which leads to its destruction. To avoid this, corrosion inhibitors are necessary. Organic compounds have been widely used as corrosion inhibitors. Many organic corrosion inhibitors have been developed nowadays. In the literature, organic compounds comprising N, O, S and P heteroatoms are described, which reduce corrosion rate. The organic compounds are adsorbed on the metal surface, forming a thin layer. Adsorption occurs either through electrostatic interaction or, in some cases, the formation of covalent bonds. The work aimed to study isothiuronic salts as corrosion inhibitors to evaluate their protective properties using the polarisation curves method. Objects of research were isothiuronic compounds containing two active centres separated by saturated and unsaturated carbon bonds (structures 1-3). In structures 4-7, one isothiuronic fragment has different propylene substituting groups. It has been previously shown that these compounds can act as effective brightening agents when applying nickel coatings. A model solution with a density of 1.12 g/cm3 was prepared to study the corrosion inhibitors. The corrosion inhibitor concentration was 400 mg/L. Studies have shown that the compounds with two isothiuronic moieties do not always exhibit improved properties for inhibiting metal degradation in a corrosive environment. In particular, they showed worsening of the inhibiting properties for samples made of steel 20 and identical properties for that made of steel 3.

Solution structure of multi-domain protein ER-60 studied by aggregation-free SAXS and coarse-grained-MD simulation

Multi-domain proteins (MDPs) show a variety of domain conformations under physiological conditions, regulating their functions through such conformational changes. One of the typical MDPs, ER-60 which is a protein folding enzyme, has a U-shape with four domains and is thought to have different domain conformations in solution depending on the redox state at the active centres of the edge domains. In this work, an aggregation-free small-angle X-ray scattering revealed that the structures of oxidized and reduced ER-60 in solution are different from each other and are also different from those in the crystal. Furthermore, structural modelling with coarse-grained molecular dynamics simulation indicated that the distance between the two edge domains of oxidized ER-60 is longer than that of reduced ER-60. In addition, one of the edge domains has a more flexible conformation than the other.

Canadian National Electrophysiology Ablation Registry Report 2011-2016

Background/Purpose: Interventional cardiac electrophysiology (EP) is a rapidly evolving field in Canada; a nationwide registry was established in 2011 to conduct a periodic review of resource allocation. Methods: The registry collects annual data on EP lab infrastructure, imaging, tools, human resources, procedural volumes, success rates, and wait times. Leading physicians from each EP lab were contacted electronically; participation was voluntary. Results: All Canadian EP centres were identified (n=30); 50% and 45% of active centres participated in the last 2 instalments of the registry. A mean of 508±270 standard and complex catheter ablation procedures were reported annually for 2015-2016 by all responding centres. The most frequently performed ablation targets atrial fibrillation (PVI) arrhythmia accounting for 36% of all procedures (mean=164±85). The number of full time physicians ranges between 1 and 7 per centre, (mean=4). The mean wait time to see an electrophysiologist for an initial non-urgent consult is 23 weeks. The wait time between an EP consult and ablation date is 17.8 weeks for simple ablation, and 30.1 weeks for AF ablation. On average centres have 2 (range: 1-4) rooms equipped for ablations; each centre uses the EP lab an average of 7 shifts per week. While diagnostic studies and radiofrequency ablations are performed in all centres, point-by-point cryoablation is available in 85% centres; 38% of the respondents use circular ablation techniques. Conclusion: This initiative provides contemporary data on invasive electrophysiology lab practices. The EP registry provides activity benchmarks on national trends and practices.

Practical use of bioenergetic evaluation of sire-bulls with different quality of semen production

For modern cattle industry, it is very important to evaluate bull-sires of different breeds by semen quality. The relevance of this problem arises in the context of development of artificial insemination technologies and biotechnology, the increasing role of sire-bulls in the genetic improvement of the herd, which makes it possible to significantly change the breed composition of herds in large regions in a short period of time. In cattle breeding, sires of Black-and-white and Holstein black-and-white breeds, which are imported into the Russian Federation, are used almost throughout the country. The purpose of the study is to assess the practical possibility of using the measured data of the bioelectric potential of superficially localized biologically active centres of sire-bulls to evaluate the quality of their semen production. The subject of the study was the semen production of the bulls of Black-and-white and Holstein blackand-white breeds. The groups were formed according to the principle of analogues; the bulls were from 2 to 4 years old; the body weight was from 700 to 800 kg. As a result of evaluating the sperm quality in sire-bulls with a high level of biopotential of the superficially localized biologically active centres, in the field of vision of the preparation, spermatozoa with an intact acrosome were found, which amounted to 96.5% of the total number of spermatozoa of the preparation and had a significant difference with the experimental group. The use of bioenergetic data of the superficially localized biologically active centres makes it possible to evaluate the sperm quality before semen collection and thereby, reduce the time and labour costs for low-quality ejaculates culling.

Analysis of the physicochemical and sorption characteristics of composites based on zeolite and chamotte clay

Clays and aluminosilicate materials are known as effective sorbents for purification of wastewater from various types of contaminants. Some properties and sorption activity of materials based on the zeolite of Shankanai deposit and Chamotte clay towards Cd2+ ions were analyzed in the present work. The structural characteristics of the studied objects, their qualitative and quantitative composition were determined by the SEM and EDAX methods. It was found that maximum adsorption capacity (qe) of the initial zeolite for extraction Cd2+ ions is (7.3±0.11) mg/g, while for Chamotte clay this value equals to (5.3±0.12) mg/g. After modification with polyvinylpyrrolidone, qe increased to (10.1±0.08) mg/g for zeolite, and (8.5±0.15) mg/g for Chamotte clay. Developed specific surface of the composite material (sorbent) and complexation with the active centres of thepolymer couldbe a resultof Cd2+ ions binding.

It takes two to Tango: Synthesis of cytotoxic quinones containing two redox active centres with potential antitumour activity

We report a new synthesis of 48 new quinone-based derivatives via click chemistry and their subsequent evaluation against cancer cell lines and the control L929 murine fibroblast cell line. These...

Are antibacterial effects of non-antibiotic drugs random or purposeful because of a common evolutionary origin of bacterial and mammalian targets?

Purpose Advances in structural biology, genetics, bioinformatics, etc. resulted in the availability of an enormous pool of information enabling the analysis of the ancestry of pro- and eukaryotic genes and proteins. Methods This review summarizes findings of structural and/or functional homologies of pro- and eukaryotic enzymes catalysing analogous biological reactions because of their highly conserved active centres so that non-antibiotics interacted with bacterial targets. Results Protease inhibitors such as staurosporine or camostat inhibited bacterial serine/threonine or serine/tyrosine protein kinases, serine/threonine phosphatases, and serine/threonine kinases, to which penicillin-binding-proteins are linked, so that these drugs synergized with β-lactams, reverted aminoglycoside-resistance and attenuated bacterial virulence. Calcium antagonists such as nitrendipine or verapamil blocked not only prokaryotic ion channels but interacted with negatively charged bacterial cell membranes thus disrupting membrane energetics and inducing membrane stress response resulting in inhibition of P-glycoprotein such as bacterial pumps thus improving anti-mycobacterial activities of rifampicin, tetracycline, fluoroquinolones, bedaquilin and imipenem-activity against Acinetobacter spp. Ciclosporine and tacrolimus attenuated bacterial virulence. ACE-inhibitors like captopril interacted with metallo-β-lactamases thus reverting carbapenem-resistance; prokaryotic carbonic anhydrases were inhibited as well resulting in growth impairment. In general, non-antibiotics exerted weak antibacterial activities on their own but synergized with antibiotics, and/or reverted resistance and/or attenuated virulence. Conclusions Data summarized in this review support the theory that prokaryotic proteins represent targets for non-antibiotics because of a common evolutionary origin of bacterial- and mammalian targets resulting in highly conserved active centres of both, pro- and eukaryotic proteins with which the non-antibiotics interact and exert antibacterial actions.

Premna odorata: Seasonal Metabolic Variation in the Essential Oil Composition of Its Leaf and Verification of Its Anti-Ageing Potential via In Vitro Assays and Molecular Modelling

The metabolic variation in the essential oil composition of Premna odorata leaves obtained from different seasons was quantitatively and qualitatively determined employing GC/MS (Gas Chromatography coupled with Mass Spectrometry) and GC/FID (Gas chromatography equipped with flame ionization detector) techniques. It displayed the existence of 97 constituents accounting for 94.19%, 92.27%, 91.95% and 92.63% for POS (spring), POM (summer), POA (autumn) and POW (winter) whole essential oils. β-Caryophyllene constituting the main metabolite in the oil in the different seasons. To better visualize the differences between them, GC data were exposed to chemometric analysis. A PCA (principal component analysis) score plot revealed the closeness of POS and POW. Molecular modelling on collagenase, elastase and hyaluronidase enzymes active centres shows that different compounds existing in the essential oil of Premna odorata leaves shows binding to the active sites with variable degrees that suggested its anti-ageing potential. Palmitic acid displayed the highest fitting for both the collagenase and elastase active centres in both pH-based and rule-based ionization methods with ∆G equals −78.27 and −44.77 kcal/mol, respectively; meanwhile, heptacosane showed the highest fitting score in the hyaluronidase centre with ∆G = −43.78 kcal/mol. In vitro assays consolidates the obtained modelling studies in which essential oil shows considerable anti-elastase and anti-hyaluronidase potential as evidenced by their IC50 values being 49.3 and 37.7 μg/mL, respectively; meanwhile, the essential oil of Premna odorata leaves displayed mild anti-collagenase potential. Thus, it can be concluded that Premna odorata could serve as a promising anti-ageing naturally occurring drug that could be effectively incorporated by pharmaceutical industries in cosmetics combating ageing and skin wrinkling.