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排序方式: 共有208条查询结果,搜索用时 109 毫秒
21.
Andriy O.NAGORNIY 《中国耐火材料》2019,(1)
The ceramic setting binders obtained by means of the raw mix mechano-chemical processing(mechanical dispersion and chemical interaction processes combination), used for bonding refractory concretes, become more available with a subsequent increased interest in their properties because they develop initial strength during a heat up of the units within 8-10 h, in contrast to 24 h after placement for high Al_2O_3 cements(HAC). This strength development enables high temperature processing units to be relined with minimum turnaround time, thus providing a favored cost/performance ratio. The present paper identifies the predominant phosphate phases responsible for developing good mechanical-strength properties of zirconia and alumina concretes bonded with mechano-chemical binders. It sets out the colloid and crystalline phases resulted from interphase interaction that provide the basis for high concentrated bonding suspensions(HCBS) technology useful to the refractory industry. 相似文献
22.
Marta Semkiv Iwona Kata Orysya Ternavska Wladimir Sibirny Kostyantyn Dmytruk Andriy Sibirny 《Yeast (Chichester, England)》2019,36(5):329-339
Production of fuel ethanol is one of the possible ways to utilize crude glycerol, substantial amounts of which are produced by biodiesel industry. Earlier, we have described construction of the recombinant strains of methylotrophic thermotolerant yeast Ogataea polymorpha with simultaneous overexpression of the genes PDC1 and ADH1, which produced increased amounts of ethanol from glycerol. In this work, we have further improved these strains by overexpression of genes involved either in oxidative (through dihydroxyacetone) or phosphorylative (through glycerol-3-phosphate) pathway of glycerol catabolism, as well as heterologous gene coding for glycerol transporter FPS1 from Komagataella phaffii (formerly, Pichia pastoris). Obtained recombinant strains produced up to 10.7 g/L of ethanol (with ethanol productivity 30 mg/g of biomass/hr and yield 132 mg/g of consumed glycerol) from pure glycerol and up to 3.55 g/L of ethanol (with ethanol productivity 11.6 mg/g of biomass/hr and yield 72.3 mg/g of consumed glycerol) from crude glycerol as a carbon source, which is approximately 15 times more relative to that of the O. polymorpha wild-type strain and 2.2 more relative to the earlier constructed strain. 相似文献
23.
Weis D Shotyk W Boyle EA Kramers JD Appleby PG Cheburkin AK 《The Science of the total environment》2002,292(1-2):7-18
The temporal evolution of atmospheric lead deposition and its possible sources were assessed in eastern Canada and in western Scotland, using blanket peat bogs as geochemical archives. Short cores were taken from two remote sites located close to the sea. Significant lead enrichments in the upper layers at both sites reflect the increasing emission of lead into the atmosphere due to anthropogenic activities during the last century. At the Scottish site, a region under aeolian influence from Europe, anthropogenic derived lead could be recognized by the distinctive unradiogenic composition (206Pb/207Pb ratios down to approximately 1.115), being clearly different from the pre-industrial values (206Pb/207Pb approximately 1.166). In contrast, the lead pollution in eastern Canada (influenced by North American sources) is identified by a more radiogenic lead isotope composition (206Pb/207Pb ratios up to approximately 1.199) compared to preindustrial values (206Pb/207Pb approximately 1.161). Emission inventories and isotope characteristics suggest that industrial (coal burning, mining) and traffic (leaded gasoline) outputs are the most likely sources during the first and the second half of the 20th century, respectively, in both, western Scotland and eastern Canada alike. The Scottish record is in line with previous studies of past atmospheric lead deposition. However, the Canadian deposit suggests that the wind derived, pre-industrial lead, is less radiogenic as previously implied using sediment archives. These results are thus the first to report pre-industrial lead isotope ratios and concentrations of atmospheric derived aerosols in North America. 相似文献
24.
25.
Park YS Dmytruk A Dmitruk I Yasuto N Kasuya A Takeda M Ohuchi N 《Journal of nanoscience and nanotechnology》2007,7(11):3750-3753
Very stable and small CdSe nanoparticles (NPs) were synthesized from the aqueous solutions containing L-cysteine (Cys) at room temperature. The Cys-capped CdSe NPs showed a very sharp excitonic peak at 420 nm. Its very small full width at half maximum (18 nm) indicates very high quality of the CdSe NPs. Their absorption features experienced little change over a month, implying an excellent stability of the CdSe NPs. The synthesis conditions were very critical to the optical property and stability of the CdSe NPs: only those prepared at specific conditions (n(Se-precursor)/n(Cd-precursor) = 0.25-0.5, n(Cys)/n(Cd-precursor) = approximately 9, pH = approximately 12) showed very sharp absorption peaks and maintained an excellent stability against time. Under these conditions, the peaks always appear at nearly the same wavelength, indicating that these NPs are selectively stable and grow at a particular size and structure. 相似文献
26.
Iryna Govbakh Vitalii Kyryk Alina Ustymenko Volodymyr Rubtsov Oleg Tsupykov Nataliya V. Bulgakova Danylo O. Zavodovskiy Inna Sokolowska Andriy Maznychenko 《International journal of molecular sciences》2021,22(21)
Impaired motor and sensory functions are the main features of Charcot–Marie–Tooth disease. Mesenchymal stem cell (MSCs) therapy is one of the possible treatments for this disease. It was assumed that MSCs therapy can improve the contractile properties of the triceps surae (TS) muscles in mice with hereditary peripheral neuropathy. Murine adipose-derived mesenchymal stromal cells (AD-MSCs) were obtained for transplantation into TS muscles of FVB-C-Tg(GFPU)5Nagy/J mice. Three months after AD-MSCs transplantation, animals were subjected to electrophysiological investigations. Parameters of TS muscle tension after intermittent high frequency electrical sciatic nerve stimulations were analyzed. It was found that force of TS muscle tension contraction in animals after AD-MSCs treatment was two-time higher than in untreated mice. Normalized values of force muscle contraction in different phases of electrical stimulation were 0.3 ± 0.01 vs. 0.18 ± 0.01 and 0.26 ± 0.03 vs. 0.13 ± 0.03 for treated and untreated animals, respectively. It is assumed that the two-fold increase in TS muscle strength was caused by stem cell therapy. Apparently, AD-MSCs therapy can promote nerve regeneration and partial restoration of muscle function, and thus can be a potential therapeutic agent for the treatment of peripheral neuropathies. 相似文献
27.
Nadine Müller Eveliina Ponkkonen Thomas Carell Andriy Khobta 《International journal of molecular sciences》2021,22(20)
Stepwise oxidation of the epigenetic mark 5-methylcytosine and base excision repair (BER) of the resulting 5-formylcytosine (5-fC) and 5-carboxycytosine (5-caC) may provide a mechanism for reactivation of epigenetically silenced genes; however, the functions of 5-fC and 5-caC at defined gene elements are scarcely explored. We analyzed the expression of reporter constructs containing either 2′-deoxy-(5-fC/5-caC) or their BER-resistant 2′-fluorinated analogs, asymmetrically incorporated into CG-dinucleotide of the GC box cis-element (5′-TGGGCGGAGC) upstream from the RNA polymerase II core promoter. In the absence of BER, 5-caC caused a strong inhibition of the promoter activity, whereas 5-fC had almost no effect, similar to 5-methylcytosine or 5-hydroxymethylcytosine. BER of 5-caC caused a transient but significant promoter reactivation, succeeded by silencing during the following hours. Both responses strictly required thymine DNA glycosylase (TDG); however, the silencing phase additionally demanded a 5′-endonuclease (likely APE1) activity and was also induced by 5-fC or an apurinic/apyrimidinic site. We propose that 5-caC may act as a repressory mark to prevent premature activation of promoters undergoing the final stages of DNA demethylation, when the symmetric CpG methylation has already been lost. Remarkably, the downstream promoter activation or repression responses are regulated by two separate BER steps, where TDG and APE1 act as potential switches. 相似文献
28.
We envision and theoretically investigate a novel behavior of a functionalized nanoparticle designed to translocate through a liquidlike membrane. We develop a statistical-mechanical approach to such a system. We predict a new mechanism for the opening of a circular energy-dominated pore on the membrane by a nanoparticle functionalized with a peptide aggregate. Following fluctuations in the position and orientation of the nanoparticle, the peptide aggregate incorporates into the membrane and locally destabilizes it. The nucleation of a pore centered at the peptide aggregate attached to the particle is a precursor to particle translocation. The subsequent opening of the pore is assisted by adhesion of the membrane to the particle. We determine the conditions in which thermal fluctuations in the membrane shape and the pore size can induce translocation of the particle. For different system parameters quantities such as the free energy, entropy, pore size, degree of particle wrapping, and the probability of spontaneous translocation are obtained. 相似文献
29.
N. Edwin Widjonarko Erin L. RatcliffCraig L. Perkins Ajaya K. Sigdel Andriy ZakutayevPaul F. Ndione Dane T. GillaspieDavid S. Ginley Dana C. OlsonJoseph J. Berry 《Thin solid films》2012,520(10):3813-3818
Bulk-heterojunction (BHJ) organic photovoltaics (OPV) are very promising thin film renewable energy conversion technologies due to low production cost by high-throughput roll-to-roll manufacturing, an expansive list of compatible materials, and flexible device fabrication. An important aspect of OPV device efficiency is good contact engineering. The use of oxide thin films for this application offers increased design flexibility and improved chemical stability. Here we present our investigation of radio frequency magnetron sputtered nickel oxide (NiOx) deposited from oxide targets as an efficient, easily scalable hole transport layer (HTL) with variable work-function, ranging from 4.8 to 5.8 eV. Differences in HTL work-function were not found to result in statistically significant changes in open circuit voltage (Voc) for poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PCBM) BHJ device. Ultraviolet photoemission spectroscopy (UPS) characterization of the NiOx film and its interface with the polymer shows Fermi level alignment of the polymer with the NiOx film. UPS of the blend also demonstrates Fermi level alignment of the organic active layer with the HTL, consistent with the lack of correlation between Voc and HTL work-function. Instead, trends in jsc, Voc, and thus overall device performance are related to the surface treatment of the HTL prior to active layer deposition through changes in active layer thickness. 相似文献
30.
Candida famata (Candida flareri) belongs to the group of so‐called ‘flavinogenic yeasts’, capable of riboflavin oversynthesis under condition of iron starvation. Some strains of C. famata belong to the most flavinogenic organisms known and were used for industrial production of riboflavin for a long time in the USA. C. famata is characterized by high salt tolerance, growing at NaCl concentrations of up to 2.5 m . Development of basic tools for the metabolic engineering of C. famata, such as a transformation system, selective markers, insertional mutagenesis, a reporter system and others, are described. The developed tools were used for cloning and identification of structural and regulatory genes of riboflavin synthesis. The construction of improved yeast strains producing riboflavin, FMN and FAD, based on the industrial riboflavin‐producing strain dep8 and its non‐reverting analogue AF4, is also described. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献