Legal obstacles to toxic chemical research

Legislative design impedes study of chemicals in the environment

Computation-guided asymmetric total syntheses of resveratrol dimers

Although computational simulation-based natural product syntheses are in their initial stages of development, this concept can potentially become an indispensable resource in the field of organic synthesis. Herein we report the asymmetric total syntheses of several resveratrol dimers based on a comprehensive computational simulation of their biosynthetic pathways. Density functional theory (DFT) calculations suggested inconsistencies in the biosynthesis of vaticahainol A and B that predicted the requirement of structural corrections of these natural products. According to the computational predictions, total syntheses were examined and the correct structures of vaticahainol A and B were confirmed. The established synthetic route was applied to the asymmetric total synthesis of (−)-malibatol A, (−)-vaticahainol B, (+)-vaticahainol A, (+)-vaticahainol C, and (−)-albiraminol B, which provided new insight into the biosynthetic pathway of resveratrol dimers. This study demonstrated that computation-guided organic synthesis can be a powerful strategy to advance the chemical research of natural products.

SURFACE WATER QUALITY IN KHARKIV RECREATIONAL AREAS: 2006-2020

The aim of the paper is to assess dynamics of water quality in four main recreational areas in Kharkiv and to develop recommendations for water quality improvement. Methods. Field and laboratory methods and analytical data processing. Results. The paper presents analysis of dynamics in water quality for four main recreational areas located in Kharkiv: Zhuravlevskiy Hydropark, Oleksiivskiy Lugopark, Udyanskiy Hydropark and Osnovyanske Lake. Period of study: 2006-2020, time: May-June and August-September. Average data are presented. Samples were analysed at certified Laboratory of Analytical Chemical Research of the Karazin Institute of Environmental Sciences. Laboratory data were compared with national UA standards and European ones. Conclusions were made for the following key parameters: dissolved oxygen and BOD5, total mineralization, biogenic substances content, oil products and surfactants, toxic heavy metals content. There is no specific dynamics on the pollution level. Conclusions. The following recommendations for improvement of water quality were developed: (i) to preform regular monitoring of water quality; (ii) to introduce regular and systematic control by one local authority; (iii) to improve infrastructure of recreational areas; (iv) to introduce regular cleaning of the recreational areas; (v) to install bio-WC; (vi) to install additional waste containers (preferably with separate waste collection); (vii) plant trees for better isolation from highways; (viii) to improve level of water treatment on WWTP; (ix) to create nature protected areas along rivers

Restoration of 18th century Chinese album

Цель данного исследования — познакомить специалистов, занимающихся изучением и реставрацией произведений китайской живописи, с опытом, полученным в Государственном Эрмитаже. В процессе изучения текстов «Альбома рисунков. Путешествие императора Цяньлуна на юг Китая» хранителем К.Ф. Самосюк была установлена дата его создания — 1751–1758 годы. Альбом с китайской живописью был исследован всесторонне: проведены физико-химические и биологические исследования, которые позволили определить методику его реставрации. В России мало информации о реставрации альбомов такого рода. Исследование и реставрация китайской живописи осложняется хрупкостью материалов — бумаги и шелка, а также утонченностью техники живописи, поэтому были выбраны неразрушающие методы исследования без взятия проб. Рассматривались также этические проблемы. Были применены физический, химический и биологический анализы для определения подходящего метода реставрации. Биологические исследования подтвердили необходимость замены старых, обветшавших страниц альбома новыми. Для реставрации и сохранения альбома были использованы традиционные китайские методы реставрации и собственный опыт. Об исследовании и реставрации китайской живописи и каллиграфии, помещенных в альбомы, не так много информации. Наряду с другими источниками впервые в отечественной практике было использовано «Иллюстрированное руководство по монтированию китайской каллиграфии и живописи» Янь Гуйжуна, 2013. В статье также рассматривается проблема адаптации альбомов с живописью и каллиграфией к новым требованиям хранения и экспонирования графики. Изменение исторической формы монтирования листов с изображениями было вызвано сильным разрушением конструкции альбома. Новая форма хранения позволила выставлять альбом отдельными листами на различных тематических выставках с возможностью их ротации на экспозиции. В данной статье показан логический ход выбора методики реставрации, основанный на результатах исследований памятника и сочетании традиционных и современных методов реставрации. The aim of the article is to share our experience of restoring the Album of Drawings. The Emperor Qian Long’s Tour of Inspection to Southern China. Curator K.F. Samosyuk has dated the album to 1751–1758. There is little information in Russia on restoring albums of this kind. Restoration of painting on paper and silk is complicated by the fragility of the support material and painting technique; we therefore chose non – destructive research methods without taking samples. Ethical problems were also considered. For the first time we used physical, chemical and biological analysis to determine the appropriate restoration method. Biological research led us to replace old, faded album pages with new ones. We then used traditional Chinese restoration methods and our own experience to restore and preserve the album. Along with other sources, for the first time in Russia, Yan Guirong’s Illustrated Instructions for the Mounting of Chinese Calligraphy and Painting, 2013 was used. The key factor, though, was the experience we gained during research secondments at Shanghai Museum. We also examine the problem of adapting painting and calligraphy albums to new requirements for the preservation and exhibiting of graphic art. Historically, album pages with illustrations were mounted in pairs and glued together. Because of the album’s severe state of deterioration we decided to mount the pages on separate sheets. This new form of preservation has enabled separate pages from the album to be shown at differently – themed exhibitions and for rotation to take place. The article shows the logical process involved in choice of restoration method based on our research findings and a combination of traditional and modern restoration methods. Chinese painting, calligraphy, album, Chinese paper, Chinese silk, conservation, restoration, physical and chemical research, biological research, exhibiting, oriental painting, State Hermitage Museum

Facile synthesis of biomass-based carbon materials nano-Ni-based catalysts and its application in selective hydrogenation of alkynes

The development of high efficiency, excellent selectivity, and super activity metal catalyst for chemical selective hydrogenation of alkynes to olefin is of great significance in the field of the chemical industry. At the same time, the development of a large number of available base metal catalysts for organic conversion remains an important objective of chemical research. Herein, we report a facile preparation of a simple, high catalytic activity, environmentally friendly, and inexpensive biomass carbon material supported nano-nickel catalyst from lignin residue. The entire preparation process of the catalyst is simple, reliable, economical, and environmentally friendly, which provides a potential utilization prospect for large-scale industrial applications of biomass-based carbon material catalysts. Biomass-based lignin residues can not only reduce the high oxidation state of nickel ions into nickel nanoparticles by the in-situ reducing gas generated during the calcination process, but the mesoporous structure of lignin residue also promotes the adsorption of nickel metal, which greatly improved the catalytic activity of biomass-based Ni-based catalysts. The simple synthetic green, cost-effective and sustainable biomass-based Ni-based catalyst shows good performance in the selective hydrogenation of phenylacetylene, reaching 97.2% conversion and 84.3% styrene selectivity, respectively.

METHANE LIQUEFACTION: Selective Conversion of Methane to Cyclohexane via Efficient Surface-Hydrogen-Transfer Catalyzed by GaN-Supported Platinum Clusters

Non-oxidative liquefaction of methane at room temperature and ambient pressure has long been a scientific “holy grail” of chemical research. In this report, we exploit an unprecedented catalytic transformation of methane exclusively to cyclohexane through effective surface-hydrogen-transfer (SHT) at the heterojunctions boundary consisting of electron-rich platinum cluster (Pt) loaded on methane-activating gallium nitride (GaN) host. The experimental analysis demonstrates that interface-induced overall reaction starts with methane aromatization to benzene initiated by the Ga-N pairs, followed by hydrogenation of benzene to cyclohexane via hydrogen transfer. The in-situ activated hydrogen at electron-rich metal Pt cluster plays a key role for the hydrogenation and enables an outstanding selectivity (as high as 89 %) towards cyclohexane, which is well-delivered even after 5 recycling runs.

A general framework for straightforward model construction of multi-component thermodynamic equilibrium systems

Mathematical modelling of molecular systems helps elucidating complex phenomena in (bio)chemistry. However, equilibrium conditions in systems consisting of more than two components can typically not be analytically determined without assumptions and resulting (semi-)numerical models are not trivial to derive by the non-expert. Here we present a framework for equilibrium models that utilizes a general derivation method capable of generating custom models for complex molecular systems, based on the simple, reversible reactions describing these systems. Several molecular systems are revisited via the framework and demonstrate the simplicity, the generality and validity of the approach. The ease of use of the framework and the ability to both analyze systems and gain additional insights in the underlying parameters strongly aids the analysis and understanding of molecular equilibrium systems. This conceptual framework severely reduces the time and expertise requirements which currently impede the broad integration of these highly valuable models into chemical research.

Identification of Pyrrolizidine Alkaloids in Senecio Plants by Liquid Chromatography-Mass Spectrometry

Pyrrolizidine alkaloids (PAs) are considered as the major constituents that cause hepatoxicity in Senecio plants. PAs can be found in about 3%–5% of the world’s flowering plants. Nowadays, the identification method of PAs by separation and preparation was too slow and lacked effective power. A rapid method to identify PAs in plants must be developed. Based on the fragmentation regularity, the hepatoxic PAs and nonhepatoxic PAs were characterized by liquid chromatography-mass spectrometry (LC-MS). The detailed structures of PAs in five Senecio plants were identified based on tandem mass spectrometry (MS/MS) spectrum and chemical research information. In the present study, some new fragmentation regularities of PAs have been found, such as product ions at m/z 122, m/z 140 and m/z 124, m/z 142, which have been discovered as the characteristic fragments of lactone and mono-esterase type of saturated PAs, respectively. Moreover, two product ions at m/z 120 and m/z 138 have been reported as the characteristic fragments of unsaturated PAs. Some of them were found in Senecio species for the first time, and some of them may be new nature product or even new compound. Finally, we classified these plants into five categories based on PAs which were identified in the present study; the result corresponded with the classification by morphology. In addition, we have found some constituents that have odd molecular weight number only in Senecio species but not in Ligularia species; the detailed structures of these non-PAs constituents need penetrating study. LC-MS was rapid and sensitive method for detecting and identifying PAs in plants. Pyrrolizidine alkaloids were the toxiferous constituent of Senecio plants. In this study, we found that PAs can be used as the characteristic constituent of Senecio species.