Characterization of chitin and its complexes extracted from natural raw sources

It is known that the main source of chitin and chitosan are shells of shrimp and other sea crustaceans. Alternative row sources of chitin, chitosan and its complexes are the lowest plants - mushrooms and insects. Also industrial wastes, especially from brewing of beer and manufacture of wine and ethanol can be used for extracting chitosan-containing products. The present research is aimed to the extraction of chitin and its complexes from alternative row sources, such as insects (cockroaches Pariplaneta Americana linnaeus and bees Apis mellifera lineaus), mushrooms (Amanita phalloides and Lactarius subdulius), waste banana wine (Kovibar and Urwibutso Inc.) and beer products (Bralirwa Inc., traditional sorghum) characteristic for Rwanda and their characterization using FTIR spectroscopy and elementary analysis. In chitin and its complexes extraction from all used raw sources, conditions for deproteinization were: 8% NaOH at 95 °C for 1 h and demineralization involved treatment with 6.7 % HCl at room temperature. Chitin and its complexes in the extracted samples were identified by FTIR spectroscopy using reference sample of Aspegillus Niger mushrooms. The presence of chitin parts causes the absorption band at 1650, 1552 and 1376 cm-1, which correspond to vibrations of amide groups amide I amide II and amide III, respectively. Using elemental analysis, the ratios of chitin and glucan parts were estimated and the percentage of chitin composition of all species was determined. For most of raw sources a fraction of chitin part was greater than that of glucan part. The chitin content of the samples studied ranged between 0.7-0.8 % of DM (dried mass) for wine (beer) waste products and 38% of dried mass (DM) for cockroaches. © 2016 Author(s).2014/239, 4.1626.2014/KRussian Foundation for Basic Research, RFBR: 14-03-00898Government Council on Grants, Russian FederationThis work was supported by the Russian Foundation for Basic Research (Grant 14-03-00898), the Program 211 of the Government of the Russian Federation No 02.A03.21.0006 and the State Tasks of the Ministry of Education (Russian Federation) No. 4.1626.2014/K and No. 2014/239 and the local Grant of University of Rwanda "Chitosancontaining materials of multifunctional application for needs of Rwanda". The authors are thankful to J.P. Intwali (Rwanda), E.V. Habumugisha (Rwanda), Ch. Ukundineza (Rwanda) and D. Niyoyita (Rwanda) for capturing insects and gathering mushrooms and their initial preparation for chitin extraction

Coordination of Cu(II) and Ni(II) in polymers imprinted so as to optimize amine chelate formation

Molecular imprinting has become an established technique. However, little was done on direct investigation of the sorbents produced. In the present work, en ESR method was used for the investigation of the complex formation processes within the sorbents imprinted with copper(II) and nickel(II). The sorbents were synthesized from a mixture of linear low molecular weight polyethyleneimine oligomers. The composition, structure and distribution of complexes in the resin phase were investigated. The effects of the synthesis conditions, loading degree and water content were examined. The presence of certain copper complexes was found to be a convenient characteristic of the imprinting efficiency. The optimum synthesis conditions for obtaining sorbents imprinted with copper(II) or nickel(II) were identified. The imprinting results in the improvement of the stability of the complexes and the selectivity and working capacity of the sorbents. The imprinted samples are also characterized by a more even distribution of chelating sites. The synthesis conditions and loading by ions allow for the regulation of the ratio between individual complexes and magnetic associates in the resin phase. This is a critical point on the future use of the metal containing imprinted sorbents as catalysts. (C) 2003 Published by Elsevier Science Ltd

Oxidative dehydrogenation of 2,3,5-trimethyl-1,4-hydroquinone in the presence of titanium dioxide hydrogel

Liquid-phase oxidative dehydrogenation of 2,3,5-trimethyl-1,4-hydroquinone in the presence of titanium dioxide hydrogel was studied by a kinetic method. Associative interactions between the substrate, oxidant, and gel were detected by voltammetry and ESR and IR spectroscopy.Russian Foundation for Basic Researc

Dynamics of pH-sensitive nitroxide radicals in water adsorbed in ordered mesoporous molecular sieves by EPR Spectroscopy

A spin pH probe technique was used to study the influence of the channel diameter on the EPR spectra of pH-sensitive nitroxide radicals (NR) located in the channels of the mesoporous molecular sieves MCM-41 and SBA-15 with diameters ranging from 2.3 to 8.1 nm. From EPR spectra analysis and the results of the NR retention by the mesoporous molecular sieves upon washing with an aqueous KCl solution, the regularities of NR molecular location inside the channels were studied. The obtained dependence of the fraction of the radical molecules in the fast motional regime (with the rotational correlation times, τc = 2 × 10-11 s-9 × 10-11s) in the channels of the mesoporous molecular sieves as a function of pH indicates that both NR in the fast and slow motional regime (with τc = 8 × 10 -9s-7 × 10-10s) may be used for estimation of the solution acidity inside the channels and of the near-surface electrical potential. © 2013 Elsevier Inc. All rights reserved

METHODOLOGICAL APPROACHES TO EVALUATING BEER AND NON-ALCOHOLIC PRODUCTS SHELF LIFE

The article discusses the relevance of developing methodological approaches to the beer and soft drinks accelerated aging method in the market. The controlled indicators selection principles, mainly affecting the quality of the finished product, and the basic equation describing the dependence of changes in indicators on the main temperature factor are given. Studies of the influence of various physical factors (temperatures in the range of 50–60 °C, UV-radiation), both individually and jointly, on the physicochemical and organoleptic characteristics of packaged water for various experimental versions did not show statistically significant changes in the normalized parameters of the basic salt and microelement composition investigated water during storage. The optimal mode of accelerated «aging» of packaged water at an elevated temperature (up to 60 °C) and UV-radiation was established. In the case of soft drinks, thermostating was used when changing the temperature regimes (heat 50 ± 2 °C / cold 6 ± 2 °C) at an exposure time of 30 days, which made it possible to observe a decrease in taste and aroma compared with the control, as well as a decrease in sweetness and the appearance of a slight plastic taste for non-carbonated drink. The influence a temperature regime change on brewing products, which cannot be estimated using the existing method due to the high turbidity, is shown.The article discusses the relevance of developing methodological approaches to the beer and soft drinks accelerated aging method in the market. The controlled indicators selection principles, mainly affecting the quality of the finished product, and the basic equation describing the dependence of changes in indicators on the main temperature factor are given. Studies of the influence of various physical factors (temperatures in the range of 50–60 °C, UV-radiation), both individually and jointly, on the physicochemical and organoleptic characteristics of packaged water for various experimental versions did not show statistically significant changes in the normalized parameters of the basic salt and microelement composition investigated water during storage. The optimal mode of accelerated «aging» of packaged water at an elevated temperature (up to 60 °C) and UV-radiation was established. In the case of soft drinks, thermostating was used when changing the temperature regimes (heat 50 ± 2 °C / cold 6 ± 2 °C) at an exposure time of 30 days, which made it possible to observe a decrease in taste and aroma compared with the control, as well as a decrease in sweetness and the appearance of a slight plastic taste for non-carbonated drink. The influence a temperature regime change on brewing products, which cannot be estimated using the existing method due to the high turbidity, is shown

TiOCl, an orbital-ordered system?

We present first principles density functional calculations and downfolding studies of the electronic and magnetic properties of the layered quantum spin system TiOCl. We discuss explicitely the nature of the exchange pathes and attempt to clarify the concept of orbital ordering in this material. An analysis of the electronic structure of slightly distorted structures according to the phononic modes allowed in this material suggests that this system is subject to large orbital fluctuations driven by the electron-phonon coupling. Based on these results, we propose a microscopic explanation of the behavior of TiOCl near the phase transition to a spin-gapped system.Comment: Some figures are compressed, for higher quality please contact the author

Surface electrical potential of ZrO2-SiO2 binary xerogels by EPR pH-sensitive spin probes

In this paper, we performed a qualitative assessment of the surface electrical potential for individual and binary xerogels based on silica and zirconia which were synthesized by hydrolysis in aqua ammonia medium. The effect of surface charge on near surface local acidity of solid-phase compositions was studied. © 2019 Author(s)

Surface Electrical Potential of ZrO2–SiO2 Binary Xerogels by EPR pH-Sensitive Spin Probes

We acknowledge the financial support of the Program 211 of the Government of the Russian Federation № 02.A03.21.0006, RFBR grants № 17-03-00641 and 18-29-12129mk, the State Task from the Ministry of the Education and Science of the Russian Federation № 4.9514.2017/8.9

Quality Assurance of Medicines: Main Scientific Approaches and Control Methods

The most important component of national health policy is the assurance of quality, efficacy, and safety of medicines entering the pharmaceutical market in the Russian Federation. In this interview, we have discussed the quality control of medicines; its interconnections with various branches of science, in particular, with analytical chemistry; and the matters of material and equipment supply with Elena L. Kovaleva (Doctor of Pharmaceutical Sciences, Deputy Director of the Centre for Medicinal Products Evaluation and Control of the Scientific Centre for Expert Evaluation of Medicinal Products of the Ministry of Health of the Russian Federation), Yuri A. Zolotov (Academician of the Russian Academy of Sciences, Full Professor, Doctor of Chemical Sciences), and Dmitry V. Somov (Candidate of Pharmaceutical Sciences, Acting Director General of the Information and Methodological Center for Expertise, Accounting, and Analysis of the Circulation of Medicinal Products of the Federal Service for Surveillance in Healthcare)

Assessment and Control of Organic Impurities in Medicinal Products: A Review

INTRODUCTION. The determination of impurities is a key requirement for the quality assessment of medicines because impurities can significantly impact the quality and therapeutic effectiveness. Pharmacopoeias are the most  important  scientific and methodological guidelines for manufacturers developing medicinal product specifications and regulators assessing these specifications as part of registration dossiers. Therefore, it is essential to harmonise national and international approaches to impurities.AIM. This study aimed to analyse and summarise pharmacopoeial requirements for and methodological approaches to the control, evaluation, and identification of organic impurities in medicines.DISCUSSION. The authors compared requirements for the control of organic impurities in small-molecule medicines set forth in national and international pharmacopoeias and guidelines of the International Council for Harmonisation of Technical Requirements for Medicinal Products for Medical Use (ICH) and the Eurasian Economic Union (EAEU). This comparison highlighted the differences in current approaches that require further harmonisation of the existing regulatory documentation. Additionally, this study analysed the popularity, advantages, and disadvantages of different options for determining impurities in two-component combination products (i.e. identified and/or unidentified impurities in one or each of the active substances). The analysis demonstrated the need to control nitrosamines and genotoxic impurities and to use selective and highly sensitive chromatographic methods.CONCLUSIONS. When drafting  pharmacopoeial  monographs  for  medicinal products, experts should consider the general approach set forth in the EAEU pharmacopoeia and regulations and in the ICH Q3B guideline. This approach recommends that process-related impurities of active substances should not be controlled at the medicinal product level. Therefore, pharmacopoeial monographs for active substances should distinguish degradation products from process-related impurities. Impurities should be determined for each active substance to ensure the quality and safety of fixed combination medicinal products. Priorities for improving the methodological approach to the control of organic impurities include using reference standards for impurities and acknowledging the necessity of impurity quantification