The effect of supported MoOX structures on the reaction pathways of propene formation in the metathesis of ethylene and 2-butene

The kind of surface MoOX structures on Al2O3–SiO2 was found to determine propene selectivity in the metathesis of ethylene and 2-butene. Compared to isolated tetrahedral MoOX species, their polymerized octahedral counterparts show significantly lower activity for isomerisation of 2- to 1-butene thus hindering non-selective metathesis of these butenes. In addition, they reveal higher ability to engage ethylene in propene formation

Highly selective and stable propane dehydrogenation to propene over dispersed VO_x-species under oxygen-free and oxygen-lean conditions

For the first time, we reported on a highly selective propane dehydrogenation to propene over SiO2- supported dispersed VOx species under oxygen-free and oxygen-lean conditions. Propene selectivity above 80% was achieved with propane conversions above 45% at 823–843 K. At operation under oxygenlean conditions, consecutive propene conversion to COx was significantly suppressed and propene was formed additionally via the highly selective non-oxidative dehydrogenation route over the same catalyst. Usage of SiO2 supports (MCM-41, SBA-15, SiO2) with no strong acid sites and co-feeding of small O2 amounts lead to very limited coke formation (<2 wt. % after 20 h on-stream operation). This results in only slight decrease in time-on-stream performance (ca. 10% of deactivation during 20 h)

Ферментные системы для фрагментации основной цепи рамногалактуронановых участков протопектинового комплекса растительной ткани

Special features of the protopectin complex structure of plant tissue suggest the necessity of performing point destruction of certain glycoside bonds in the structure of rhamnogalacturonan polymer chains for industrial production of pectin. These chains include homogalacturonan sites and branching zones. As the homogalacturonan fragments of the protopectin complex carry the main functional load, glycoside bonds between residues of rhamnose and galacturonic acid are targeted bonds. For their directional destruction, it is most expedient to use enzymes of lyase and hydrolase action. The aim of this review is to systemize notions of molecular specific features of enzymes of lyase and hydrolase action that catalyze the process of enzymatic destruction of the rhamnogalacturonan main chain. The paper examines systematics of lyase and hydrolase enzymes by mechanism of destruction of glycoside bonds and by molecular structure. It is shown that the classification data intercross, as a result, each family can include one or several enzyme groups. The review shows the main structural difference of enzymes of lyase and hydrolase action that consists in the obligatory presence of Ca2+ cations in the composition of lyase enzymes. These cations take part in stabilization of conformation of the enzyme molecule and in the catalytic process per se blocking the residue of galacturonic acid. Ca2+ cations are absent in the composition of targeted hydrolase enzymes. Molecular specific features of lyase enzymes determine sensitivity of their catalytic activity to the presence of Ca2+ cations in the system. Exceeding certain concentration can lead to the antagonistic effect. There is no unambiguous idea of this regarding hydrolase enzymes. The review demonstrates the necessity of studying approaches to assessment of expediency of preliminary partial removal of cations from the substrate.Особенности структуры протопектинового комплекса растительной ткани предполагают необходимость проведения точечной деструкции отдельных гликозидных связей в структуре полимерных цепей рамногалактуронана для промышленного производства пектина. В состав этих цепей входят гомогалактуронановые участки и зоны ветвления. В связи с тем, что основную функциональную нагрузку несут гомогалактуронановые фрагменты протопектинового комплекса, целевыми являются гликозидные связи между остатками рамнозы и галактуроновой кислоты. Для их направленной деструкции наиболее целесообразно использовать ферменты лиазного и гидролазного действия. Целью данного обзора является систематизация представлений о молекулярных особенностях ферментов лиазного и гидролазного действия, катализирующих процесс ферментативной деструкции основной цепи рамногалактуронана. В статье рассматриваются систематики лиазных и гидролазных ферментов по механизму деструкции гликозидных связей и по молекулярной структуре. Показано, что данные классификации пересекаются, в результате чего в каждое семейство может входить как одна, так и несколько групп ферментов. В обзоре показано основное структурное отличие ферментов лиазного и гидролазного действия, заключающееся в обязательном присутствии в составе лиазных ферментов катионов Ca2+. Эти катионы участвуют в стабилизации конформации молекулы фермента и в самом каталитическом процессе, блокируя остаток галактуроновой кислоты. В составе целевых гидролазных ферментов катионы Ca2+ отсутствуют. Молекулярные особенности лиазных ферментов определяют чувствительность их каталитической активности к присутствию катионов Ca2+ в системе. Превышение определенной концентрации способно приводить к антагонистическому эффекту. В отношении гидролазных ферментов однозначное представление на этот счет отсутствует. Показана необходимость исследования подходов к оценке целесообразности предварительного частичного удаления катионов из субстрата

Morphophysiological peculiarities of productivity formation in columnar apple varieties

Received: December 30th, 2021 ; Accepted: February 22nd, 2022 ; Published: March 4th, 2022 ; Correspondence: [email protected] of generative buds is one of the most important biological processes of plant transition from vegetative to generative state. This process is key to the problem of creating regular fruit-bearing and early-fruiting plantations. The article provides information on the organogenesis of buds in plants of columnar apple varieties in the Forest-Steppe of Ukraine, which allows establishing the features of this process in complex fruit formations of different ages, and the levels of their productivity and longevity. Research to study the organogenesis of different-age fruit formations of columnar apple varieties was conducted in the northern part of the Forest-Steppe of Ukraine during 2016–2020. The efficiency of realization the plants biological potential of all studied columnar apple varieties at III–IV and V–IX stages of organogenesis was high: the largest number of buds from their total number differentiated into generative on trees varieties ‘Sparta’, ‘President’, ‘Bilosnizhka’, ‘Valuta’ and ‘Tantsivnytsia’ (37–51%), the smallest in ‘Favoryt’ and ‘Bolero’. The biggest number of flowers per one potentially generative bud was formed by plants of ‘Tantsivnytsia’ and ‘Bilosnizhka’ varieties. The lowest level of ovarian loss during the X stage of organogenesis was observed on plants of ‘Valuta’, ‘President’, and ‘Tantsivnytsia’ varieties (41–49%), and the highest - in ‘Favoryt’ variety (up to 83%). More effective realization of potential productivity at the XI stage of organogenesis occurred in plants of ‘President’, ‘Valuta’ and ‘Tantsivnytsia’ varieties; their trees on one potentially generative bud formed - 0.27–0.38 fruits. The coefficient of determination indicates that the influence of meteorological conditions of the year on the passage of III–IV stages of organogenesis is 46%; V–IX stages - 42%; Stage X - 17%; Stage XI - 24%

Theory of transverse spin dynamics in a polarized Fermi liquid and an itinerant ferromagnet

The linear equations for transverse spin dynamics in a weakly polarized degenerate Fermi liquid with arbitrary relationship between temperature and polarization are derived from Landau-Silin phenomenological kinetic equation with general form of two-particle collision integral. Unlike the previous treatment where Fermi velocity and density of states have been taken as constants independent of polarization here we made derivation free from this assumption. The obtained equations are applicable for description of spin dynamics in paramagnetic Fermi liquid with finite polarization as well in an itinerant ferromagnet. In both cases transverse spin wave frequency is found to be proportional to the square of the wave vector with complex constant of proportionality (diffusion coefficient) such that the damping has a finite value at T=0. The polarization dependence of the diffusion coefficient is found to be different for a polarized Fermi liquid and for an itinerant ferromagnet. These conclusions are confirmed by derivation of transverse spin wave dispersion law in frame of field theoretical methods from the integral equation for the vortex function. It is shown that similar derivation taking into consideration the divergency of static transverse susceptibility also leads to the same attenuating spin wave spectrum.Comment: 7 pages, no figure

Nanohyperthermia of malignant tumors. II. In vivo tumor heating with manganese perovskite nanoparticles

Objectives: To evaluate the ability of manganese perovskite nanoparticles (lanthanum-strontium manganite) to heat the tumor tissue in vivo under action of external alternating magnetic field. Materials and Methods: The magnetic fluid on the basis of nanoparticles of perovskite manganite was tested in the heating experiments using of alternating magnetic field of frequency 300 kHz and amplitude 7.7 kA/m. Guerin carcinoma was transplanted into the muscle of rat. Magnetic fluid was injected intramuscularly or intratumorally. Temperature was measured by copper-constantan thermocouple. Results: Temperature of magnetic fluid was increased by 56 °C for 10 min of alternating magnetic field action. Administration of magnetic fluid into the muscle followed by alternating magnetic field resulted in the elevation of muscle temperature by 8 °C after 30 min post injection. Temperature of the tumor injected with magnetic fluid and treated by alternating magnetic field was increased by 13.6 °C on the 30 min of combined influence. Conclusion: In vivo study with rat tissue has demonstrated that magnetic fluid of manganite perovskite injected in the tumor increases the tumor temperature under an alternating magnetic field. Obtained results emphasize that magnetic fluid of manganite perovskite can be considered as effective inducer of tumor hyperthermia

Efficiency of productivity potential realization of different-age sites of a trunk of grades of columnar type apple-trees

Received: April 15th, 2022 ; Accepted: May 15th, 2022 ; Published: May 17th, 2022 ; Correspondence: [email protected] article provides information about buds organogenesis in plants of columnar apple cultivars in the Forest-Steppe of Ukraine (Kyiv), which allows to establish the features of this process in complex fruit formations of different ages, and their productivity and longevity. We recommend studying of apple trees productivity in the process of its formation by analyzing of rudimentary organs formation and their consistent development into vegetative and generative organs, which are elements of productivity. Studies of organogenesis different-age fruit formations of columnar apple cultivars were conducted in the northern part of the Forest-Steppe of Ukraine during 2016–2020. It was established that separate age sections of columnar apple trees trunk formed different initial productivity potential. In plants of all studied varieties and age groups, the laying of generative buds, the implementation of reproductive elements in V–IX and X–XI stages of organogenesis were more effective in older age areas of the trunk. Complex fruit formations, regardless of the trunk age where they are placed, form a high potential for productivity, which is effectively realized. The dependence of the formation and productivity potential realization on the stages of organogenesis and meteorological factors is established

Science Requirements and Conceptual Design for a Polarized Medium Energy Electron-Ion Collider at Jefferson Lab

This report presents a brief summary of the science opportunities and program of a polarized medium energy electron-ion collider at Jefferson Lab and a comprehensive description of the conceptual design of such a collider based on the CEBAF electron accelerator facility.Comment: 160 pages, ~93 figures This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC05-06OR23177, DE-AC02-06CH11357, DE-AC05-060R23177, and DESC0005823. The U.S. Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce this manuscript for U.S. Government purpose