730 research outputs found
Исследования возможности получения самовспеенивающегося композитнного материала путем аккумулирующей многослойной прокатки
Modeling the balanced development of the region in the transition to renewable energy and maintaining the carbon cycle in land use
The article provides the author’s model for assessing the level of sustainability in the development of a region due to an increase in the share of alternative energy sources and on the premise of maintaining a carbon balance. It was taken into account that the possibility of maintaining the carbon balance in the region is greatly influenced by agricultural activities and landscape features of the region. Thus, in some regions it is necessary to allocate additional areas of ecosystems with a special nature management regime to maintain the carbon cycle. The model generated was tested on the example of the regions of the Ural Federal District of the Russian Federation. It has been established that carbon dioxide emission from anthropogenically disturbed territories is present in four regions of the district: Sverdlovsk (17.9 million tons), Chelyabinsk (45.04 million tons), Kurgan (40.9 million tons) and Tyumen (13.03 million tons) regions. Thus, even if the share of renewable energy in the energy balance increases to 37-93%, and the general balance is achieved, the carbon cycle is still disrupted. In order to preserve it, additional inclusion of up to 8.5-57.4% of the region territories into the special nature management regime is required
Integral assessment of low-carbon energy sources effectiveness based on multi-criteria analysis
The study applies the multi-criteria analysis of various low-carbon energy sources to assess their ecological and economical effectiveness. The work is specific by researching renewable energy sources as well as traditional ones which take hydrocarbon fuel by using innovative technologies of carbon dioxide capturing and its storage. The analysis applies three parameters: LCOE (Levelised Cost of Energy)/LEC (Levelized Energy Cost), specific value of carbon dioxide emission in electrical power generation and total MI (Material Input) - numbers. The study results in educing low-carbon energy sources which not only lead to the most reduction of carbon dioxide emission with least costs but also help reduce the general negative impact on the environment due to decreasing violence of biosphere material energy flows. The research states that wind power plants are the most effective, followed by solar and geothermal energy sources. Gas and coal-fired power stations, using technologies of carbon dioxide capturing, are less effective than renewable energy sources. Nevertheless, despite significant divergence in two out of three parameters, they have an identical summative assessment of efficiency because gas power stations have higher utilization costs than coal-fired power stations
Chiral separation of substituted phenylalanine analogues using chiral palladium phosphine complexes with enantioselective liquid–liquid extraction
Chiral palladium phosphine complexes have been employed in the chiral separation of amino acids and phenylalanine analogues in particular. The use of (S)-xylyl-BINAP as a ligand for the palladium complex in enantioselective liquid–liquid extraction allowed the separation of the phenylalanine analogues with the highest operational selectivity reported to date. 31P NMR, FTIR, FIR, UV-Vis, CD and Raman spectroscopy methods have been applied to gain insight into the binding mechanism of the amino acid substrates with the chiral palladium phosphine complexes. A complexation in a bidentate fashion is proposed.
Mathematical model of stacked one-sided arrangement of the burners
Paper is aimed at computer simulation of the turbulent methane-air combustion in upgraded U-shaped boiler unit. To reduce the temperature in the flame and hence NOx release every burner output was reduced, but the number of the burners was increased. The subject of studying: complex of characteristics with space-time fields in the upgraded steam boiler E-370 with natural circulation. The flare structure, temperature and concentrations were determined computationally
Enantioseparation on Riboflavin Derivatives Chemically Bonded to Silica Gel as Chiral Stationary Phases for HPLC
International audienceAcetylated and/or 3,5-dimethylphenylcarbamated riboflavins were prepared and the resulting riboflavin derivatives as well as natural riboflavin were regioselectively immobilized on silica gel through chemical bonding at the 5’-O- or 3-N-position of the riboflavin to develop novel chiral stationary phases (CSPs) for enantioseparation by high-performance liquid chromatography (HPLC). The chiral recognition abilities of the obtained CSPs were significantly dependent on the structures of the riboflavin derivatives, the position of the chemical bonding on the silica gel, and the structures of the racemic compounds. The CSPs bonded at the 5’-O-position on the silica gel tended to well separate helicene derivatives, while the CSPs bonded at the 3-N-position composed of acetylated and 3,5-dimethylphenylcarbamated riboflavins showed a better resolving ability toward helicene derivatives and bulky aromatic racemic alcohols, respectively, and some of them were completely separated into the enantiomers. The observed difference in the chiral recognition abilities of these riboflavin-based CSPs is discussed based on the difference in their structures, including the substituents of riboflavin and the positions immobilized on the silica gel
ПОЛИ-4-ВИНИЛПИРИДИНИЕВЫЕ НАНОГУБКИ В КАЧЕСТВЕ МОДИФИКАТОРОВ ЭЛЕКТРОФОРЕТИЧЕСКИХ СИСТЕМ ДЛЯ РАЗДЕЛЕНИЯ ЗАРЯЖЕННЫХ АНАЛИТОВ
Novel hydrophilic ionic polymer nanoparticles based on the N-alkylated hypercrosslinked poly-4-vinylpyridine (nanosponges ‒ NS) have porous structure, pH-independent positive charge and contain the aromatic rings. These nanosponges have not yet been studied in the capillary electrophoresis mode, but their characteristics suggest the possibility of creating the fused silica capillary walls coating for the separation of anionic and cationic analytes. In the current research, the authors, for the first time, have proposed the approaches to the formation of coatings based on the nanosponges with a molecular weight of 400 and 10 kDa. It was established that the stability of such coatings could be achieved by the introduction of NS into the background electrolyte. The pH range of background electrolytes for the subsequent electrophoretic experiments was determined to be from 4 to 9. The NS-based coatings were compared with the previously investigated coatings based on the crosslinked polystyrene nanoparticles (NPs), functionalized with the quaternary ammonium groups. Capillaries modified with NS (400 kDa) were tested for the electrophoretic separations of wide range of analytes: carboxylic acids, aminoacids, fluoroquinoline antibiotics, biogenic amines, and proteins. The separation selectivity of carboxylic acids on the NS-modified capillaries was different from the separation selectivity on the capillaries modified with NPs, functionalized with quaternary ammonium groups. NS affect the separation selectivity of aminoacids by interacting with these analytes, while for fluoroquinoline antibiotics NS act as an agent generating the reversed electroosmotic flow (EOF). The modification of fused silica capillary walls by NS with molecular mass of 400 kDa prevented the sorption of biogeniс amines and lyzocyme protein during their electrophoretic separation.Keywords: capillary electrophoresis, nanoparticles, coatings of fused silica capillary wallsDOI: http://dx.doi.org/10.15826/analitika.2019.23.2.006(Russian)D.A. Polikarpova1, D.V. Makeeva1, L.A. Kartsova1, V.A. Davankov2, L.A. Pavlova2 1Saint-Petersburg State University, Institute of Chemistry,Universitetskii pr. 26., St. Petersburg, Petergof, 198504, Russian Federation2A.N. Nesmeyanov Institute of Organoelement Compounds of Russian Academy of Sciences, Vavilova St. 28, Moscow, 119334, Russian FederationНовые гидрофильные ионные полимерные наночастицы на основе N-алкилированного сверхсшитого поли-4-винилпиридина (наногубки – НГ) имеют пористую структуру, несут рН-независимый положительный заряд и содержат ароматические звенья, что позволяет предполагать возможность формирования покрытий стенок кварцевого капилляра на их основе для разделения анионных и катионных аналитов. В рамках исследования впервые предложены подходы к формированию покрытий на основе наногубок с молекулярной массой 400 и 10 кДа. Показано, что для обеспечения стабильности таких покрытий необходимо введение НГ в состав фонового электролита (ФЭ). Определен рабочий диапазон рН ФЭ (4-9) для последующих электрофоретических экспериментов. Результаты сопоставлены с полученными нами ранее экспериментальными данными по формированию покрытий на основе наноразмерных частиц (НЧ) сшитого полистирола, функционализированных четвертичными аммонийными группами. Для выявления перспектив покрытия на основе НГ с молекулярной массой 400 кДа рассмотрен широкий спектр аналитов: карбоновые кислоты, аминокислоты, антибиотики фторхинолонового ряда, биогенные амины, белки. Разделение карбоновых кислот на таких капиллярах характеризуется иной селективностью по сравнению с капиллярами, покрытыми НЧ, функционализированными четвертичными аммонийными группами. При разделении аминокислот НГ влияют на селективность разделения за счет взаимодействия с аналитами, а в случае антибиотиков НГ выступают только в роли агента, обращающего электроосмотический поток (ЭОП). Установлено, что модификация стенок капилляра НГ с молекулярной массой 400 кДа позволяет предотвращать сорбцию основных аналитов (биогенные амины, белок лизоцим) в процессе их электрофоретического разделения.Ключевые слова: капиллярный электрофорез, наночастицы, покрытия стенок капилляраDOI: http://dx.doi.org/10.15826/analitika.2019.23.3.00
Recognition of Chiral Carboxylic Anions by Artificial Receptors
Many carboxylic molecules, ranging from drugs to flavors and fragrances, contain chiral centers. As a consequence, research has been carried out in order to design and synthesize artificial receptors for carboxylic anions. Many problems have to be solved for binding anions. The results obtained in the binding of carboxylic anions by guanidine, secondary ammonium and metal-center have been selected. The last part of this review focuses on chiral recognition of carboxylic anions by organic and metal-based chiral receptors
Hyperporous Carbons from Hypercrosslinked Polymers.
Porous carbons with extremely high surface areas are produced through the carbonization of hypercrosslinked benzene, pyrrole, and thiophene. Such carbons show largely microporous and mesoporous domains and exhibit Brunaeur-Emmett-Teller surface areas up to 4300 m(2) g(-1) . The best performing material also displays exceptionally high CO2 and H2 uptakes
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