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71.
Ludmila G Echevskaya Mikhail A Matsko Tatiana B Mikenas Vladimir A Zakharov 《Polymer International》2006,55(2):165-170
Highly active supported vanadium‐magnesium catalysts (VMC) produce polyethylene (PE) with broad and bimodal molecular mass distribution (MMD) in comparison with the famous titanium‐magnesium catalysts (TMC). The effect of hydrogen as an efficient chain‐transfer agent on the MMD of PE has been studied. Increasing hydrogen concentration causes a considerable broadening of MMD of PE due to the shift of the low molecular weight peak on the MMD curve. At the same time, the high molecular weight shoulder stays at the same position even at high hydrogen concentration. This means that VMC contain two types of active centre. One type is very reactive in the chain‐transfer reaction with hydrogen. These centres produce low molecular weight PE in polymerization in the presence of hydrogen. The other type of active centre is not active in chain transfer with hydrogen. These centres produce high molecular weight PE ((1–3) × 106) and hydrogen does not affect the position of the high molecular weight shoulder. MMD data were used to analyze the kinetics of the chain‐transfer reaction with hydrogen and to calculate the rate constants of this reaction. Copyright © 2005 Society of Chemical Industry 相似文献
72.
Dmitry Rasskazov Irina Chadaeva Ekaterina Sharypova Karina Zolotareva Bato Khandaev Petr Ponomarenko Nikolay Podkolodnyy Natalya Tverdokhleb Oleg Vishnevsky Anton Bogomolov Olga Podkolodnaya Ludmila Savinkova Elena Zemlyanskaya Vadimir Golubyatnikov Nikolay Kolchanov Mikhail Ponomarenko 《International journal of molecular sciences》2022,23(15)
Synthetic targeted optimization of plant promoters is becoming a part of progress in mainstream postgenomic agriculture along with hybridization of cultivated plants with wild congeners, as well as marker-assisted breeding. Therefore, here, for the first time, we compiled all the experimental data—on mutational effects in plant proximal promoters on gene expression—that we could find in PubMed. Some of these datasets cast doubt on both the existence and the uniqueness of the sought solution, which could unequivocally estimate effects of proximal promoter mutation on gene expression when plants are grown under various environmental conditions during their development. This means that the inverse problem under study is ill-posed. Furthermore, we found experimental data on in vitro interchangeability of plant and human TATA-binding proteins allowing the application of Tikhonov’s regularization, making this problem well-posed. Within these frameworks, we created our Web service Plant_SNP_TATA_Z-tester and then determined the limits of its applicability using those data that cast doubt on both the existence and the uniqueness of the sought solution. We confirmed that the effects (of proximal promoter mutations on gene expression) predicted by Plant_SNP_TATA_Z-tester correlate statistically significantly with all the experimental data under study. Lastly, we exemplified an application of Plant_SNP_TATA_Z-tester to agriculturally valuable mutations in plant promoters. 相似文献
73.
Galina Vladimirovna Kontsevaya Ludmila Alekseevna Gerlinskaya Yury Mikhailovich Moshkin Margarita Vladimirovna Anisimova Aliya Konstantinovna Stanova Tatyana Ivanovna Babochkina Mikhail Pavlovich Moshkin 《International journal of molecular sciences》2021,22(19)
The latest vaccination campaign has actualized the potential impact of antigenic stimuli on reproductive functions. To address this, we mimicked vaccination’s effects by administering keyhole limpet hemocyanin (KLH ) to CD1 male mice and used their sperm for in vitro fertilization (IVF). Two-cell embryos after IVF with spermatozoa from control (C) or KLH-treated (Im) male mice were transferred to surrogate mothers mated with vasectomized control (C) or KLH-treated (Im) male mice, resulting in four experimental groups: C–C, Im–C, C–Im, and Im–Im. The pre-implantation losses were significantly lower in the Im–C group than in the C–Im group. At the same time, the resorption rates reduced markedly in the C–Im compared to the Im–C group. Embryo and placenta weights were significantly higher in the Im–Im group. Although the GM-CSF levels were lower in the amniotic fluid of the gestating surrogate mothers in the Im–Im group, they were strongly correlated with embryo mass. The number–size trade-off was only significant in the Im–Im group. This suggests a positive, cooperative effect of spermatozoa and seminal fluid from immune-primed males on embryo growth and the optimal distribution of surrogate mother maternal resources despite the negative impact of males’ antigenic challenge on the IVF success rate. 相似文献
74.
Vasilisa V. Krasitskaya Alexander N. Kudryavtsev Roman N. Yaroslavtsev Dmitry A. Velikanov Oleg A. Bayukov Yulia V. Gerasimova Sergey V. Stolyar Ludmila A. Frank 《International journal of molecular sciences》2022,23(10)
Starch-coated magnetic iron oxide nanoparticles have been synthesized by a simple, fast, and cost-effective co-precipitation method with cornstarch as a stabilizing agent. The structural and magnetic characteristics of the synthesized material have been studied by transmission electron microscopy, Mössbauer spectroscopy, and vibrating sample magnetometry. The nature of bonds between ferrihydrite nanoparticles and a starch shell has been examined by Fourier transform infrared spectroscopy. The data on the magnetic response of the prepared composite particles have been obtained by magnetic measurements. The determined magnetic characteristics make the synthesized material a good candidate for use in magnetic separation. Starch-coated magnetic iron oxide nanoparticles have been tested as an affinity sorbent for one-step purification of several recombinant proteins (cardiac troponin I, survivin, and melanoma inhibitory activity protein) bearing the maltose-binding protein as an auxiliary fragment. It has been shown that, due to the highly specific binding of this fragment to the starch shell, the target fusion protein is selectively immobilized on magnetic nanoparticles and eluted with the maltose solution. The excellent efficiency of column-free purification, high binding capacity of the sorbent (100–500 µg of a recombinant protein per milligram of starch-coated magnetic iron oxide nanoparticles), and reusability of the obtained material have been demonstrated. 相似文献
75.
Gabriela Petrisor Ludmila Motelica Luminita Narcisa Craciun Ovidiu Cristian Oprea Denisa Ficai Anton Ficai 《International journal of molecular sciences》2022,23(7)
Melissa officinalis is a medicinal plant rich in biologically active compounds which is used worldwide for its therapeutic effects. Chemical studies on its composition have shown that it contains mainly flavonoids, terpenoids, phenolic acids, tannins, and essential oil. The main active constituents of Melissa officinalis are volatile compounds (geranial, neral, citronellal and geraniol), triterpenes (ursolic acid and oleanolic acid), phenolic acids (rosmarinic acid, caffeic acid and chlorogenic acid), and flavonoids (quercetin, rhamnocitrin, and luteolin). According to the biological studies, the essential oil and extracts of Melissa officinalis have active compounds that determine many pharmacological effects with potential medical uses. A new field of research has led to the development of controlled release systems with active substances from plants. Therefore, the essential oil or extract of Melissa officinalis has become a major target to be incorporated into various controlled release systems which allow a sustained delivery. 相似文献
76.
Olga Levchenko Elena Dadali Ludmila Bessonova Nina Demina Galina Rudenskaya Galina Matyushchenko Tatiana Markova Inga Anisimova Natalia Semenova Olga Shchagina Oxana Ryzhkova Rena Zinchenko Varvara Galkina Victoria Voinova Sabina Nagieva Alexander Lavrov 《International journal of molecular sciences》2022,23(14)
Intellectual development disorder (IDD) is characterized by a general deficit in intellectual and adaptive functioning. In recent years, there has been a growing interest in studying the genetic structure of IDD. Of particular difficulty are patients with non-specific IDD, for whom it is impossible to establish a clinical diagnosis without complex genetic diagnostics. We examined 198 patients with non-specific IDD from 171 families using whole-exome sequencing and chromosome microarray analysis. Hereditary forms of IDD account for at least 35.7% of non-specific IDD, of which 26.9% are monogenic forms. Variants in the genes associated with the BAF (SWI/SNF) complex were the most frequently identified. We were unable to identify phenotypic features that would allow differential diagnosis of monogenic and microstructural chromosomal rearrangements in non-specific IDD at the stage of clinical examination, but due to its higher efficiency, exome sequencing should be the diagnostic method of the highest priority study after the standard examination of patients with NIDD in Russia. 相似文献
77.
Alexander I. Krivoshey Natalia I. Shkolnikova Lidiya A. Kutulya Ludmila V. Chepeleva Natalia B. Novikova 《Journal of the Society for Information Display》2004,12(2):173-177
Abstract— The induced helical pitch in liquid‐crystalline systems based on 4‐pentyl‐4′‐cyanobiphenyl (5CB) and containing chiral 6‐arylidene derivatives of 3(R)‐methylcyclohexanone has been found to change its sign and to decrease in the absolute value when exposed to the UV irradiation. After the photostationary state is reached, the pitch remains invariable regardless of any consequent light radiation. This state is characterized by a large helical twist which exceeds an initial one in more than three times, thereby making it possible to obtain compositions with the selective reflection of light in the visible spectral region. This phenomenon could be utilized in colour filters for display devices. The effect observed is caused by the effective reversible photochemical E‐Z‐isomerization of the chiral dopant. This was proved by photochemical preparative synthesis of one of the respective Z‐isomers and independent studies of its behaviour in 5CB. 相似文献
78.
A. A. Belov N. N. Kalitkin L. V. Kuzmina 《Mathematical Models and Computer Simulations》2016,8(2):155-174
Simple and robust formulas of the conjugate direction method for symmetric matrices and of the symmetrized conjugate gradient method for nonsymmetric matrices have been constructed. These methods were compared with robust forms of the conjugate gradient method and the Craig method using test problems. It is shown that stability for the round-off error can be attained when recurrent variants of the methods are used. The most reliable and efficient method for symmetric signdefinite and indefinite matrices appears to be the method of conjugate residuals. For nonsymmetric matrices, the best results have been obtained by the method of symmetrized conjugate gradients. These two methods are recommended for writing standard programs. A reliable criterion has also been constructed for the termination of the calculation on reaching background values due to the round-off errors. 相似文献
79.
Nataliya A. Vlasenko Pavel F. Oleksenko Ludmila I. Veligura Miroslav O. Mukhlyo Zinaida L. Denisova Viktor F. Zinchenko 《Journal of the Society for Information Display》2007,15(11):937-941
Abstract— The following main differences have been revealed in the characteristics of an edge thin‐film‐electroluminescent ZnS: Er,F emitter compared to those of a similar planar emitter: (1) the 1.535‐μm band more highly dominates over other bands in the EL spectrum; (2) the voltage (V) dependence of the intensity of this band is the strongest; (3) the 1.535‐μm band narrows with increasing voltage and its frequency. The above differences are explained, firstly, by smaller optical losses in the ZnS: Er,F film for the near‐infrared emission than for the visible one and, secondly, by an optical amplification over the 1.535‐μm band in the edge emitter. 相似文献
80.
Marina I. Nikolaeva Mikhail A. Matsko Tatiana B. Mikenas Ludmila G. Echevskaya Vladimir A. Zakharov 《应用聚合物科学杂志》2012,125(3):2042-2049
The data on the effect of comonomer (propylene and 1-hexene) on molecular weight (Mw), molecular weight distribution (MWD), and content of terminal double bonds were obtained for ethylene/α-olefin copolymers produced over a supported titanium–magnesium catalyst (TMC) upon polymerization in the absence of hydrogen. The experimental data on the effect of comonomer concentration on Mw of polymers were used to calculate the ratios between the effective rate constants of chain transfer with monomer and the propagation rate constant. It was shown that the effective rate constant of chain transfer with monomers increases in the row of monomers: ethylene < 1-hexene < propylene. Meanwhile, the data on the effect of copolymers on content of terminal double bonds of various types demonstrate that different reactions of chain transfer with comonomer may simultaneously occur during copolymerization. It results in simultaneous formation of terminal vinylidene and trans-vinylene bonds. Therefore, the calculated rate constants of chain transfer with comonomer are complex values, which include the rate constants of chain transfer with comonomer occurring via different mechanisms. The data on MWD, short chain branching (SCB) and terminal double bonds content of different types were obtained by molecular weight fractionation of copolymers followed by the analysis of narrow fractions. The analysis of the data on MWDs of SCB and terminal double bonds shows that active sites of the TMC are considerably heterogeneous with respect to the rates of different chain transfer reactions with monomers. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 相似文献