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排序方式: 共有286条查询结果,搜索用时 15 毫秒
81.
Pavel A. Domnin Vladislav A. Parfenov Alexey S. Kononikhin Stanislav V. Petrov Nataliya V. Shevlyagina Anastasia Yu. Arkhipova Elizaveta V. Koudan Elizaveta K. Nezhurina Alexander G. Brzhozovskiy Anna E. Bugrova Anastasia M. Moysenovich Alexandr A. Levin Pavel A. Karalkin Frederico D. A. S. Pereira Vladimir G. Zhukhovitsky Elena S. Lobakova Vladimir A. Mironov Evgeny N. Nikolaev Yusef D. Khesuani Svetlana A. Ermolaeva 《International journal of molecular sciences》2022,23(3)
Changes in bacterial physiology caused by the combined action of the magnetic force and microgravity were studied in Escherichia coli grown using a specially developed device aboard the International Space Station. The morphology and metabolism of E. coli grown under spaceflight (SF) or combined spaceflight and magnetic force (SF + MF) conditions were compared with ground cultivated bacteria grown under standard (control) or magnetic force (MF) conditions. SF, SF + MF, and MF conditions provided the up-regulation of Ag43 auto-transporter and cell auto-aggregation. The magnetic force caused visible clustering of non-sedimenting bacteria that formed matrix-containing aggregates under SF + MF and MF conditions. Cell auto-aggregation was accompanied by up-regulation of glyoxylate shunt enzymes and Vitamin B12 transporter BtuB. Under SF and SF + MF but not MF conditions nutrition and oxygen limitations were manifested by the down-regulation of glycolysis and TCA enzymes and the up-regulation of methylglyoxal bypass. Bacteria grown under combined SF + MF conditions demonstrated superior up-regulation of enzymes of the methylglyoxal bypass and down-regulation of glycolysis and TCA enzymes compared to SF conditions, suggesting that the magnetic force strengthened the effects of microgravity on the bacterial metabolism. This strengthening appeared to be due to magnetic force-dependent bacterial clustering within a small volume that reinforced the effects of the microgravity-driven absence of convectional flows. 相似文献
82.
Grigorii O. Kozhevnikov Vladislav A. Protserov Luybov A. Wasserman Ninel E. Pavlovskaya Leonid V. Golischkin Vasilii N. Milyaev Vladimir P. Yuryev 《Starch - St?rke》2001,53(5):201-210
Starches isolated at different stages of maturation (milky, waxy, complete maturation) of wrinkled peas were investigated by differential scanning calorimetry (DSC) and X‐ray diffraction (XRD). It was shown that the maturation of wrinkled peas is accompanied by changes in the structural and thermodynamic properties of starches. The melting process of milky starches could be approximated by means of a “two‐state” model. The melting process of the waxy and completely maturated starches was described as the melting of a mixture of low and high temperature populations of double‐helical type crystallites, denoted as B‐ and B*‐types, as well as the melting of Vh ‐type crystallites. The relative amounts of the three structures were determined by deconvolution of the calorimetric peaks. The values of the melting cooperative units ( ϑ ) and the thickness of the crystalline lamellae (pitch heights) for starches were determined using mathematical models describing the melting processes. The values of the ϑ for milky, waxy, and completely maturated starches were calculated as 18 and 29 anhydroglucose residues, respectively. The thickness of the crystalline lamellae of B‐type crystals in the milky, waxy, and completely maturated starches were calculated. Structural changes in starch granules during maturation of wrinkled pea are discussed. 相似文献
83.
Vladislav Kanazirev Veselina Mavrodinova Lubka Kosova Geoffrey L. Price 《Catalysis Letters》1991,9(1-2):35-42
Ga2O3/HZSM-5 catalysts prepared as intimate physical mixtures of Ga2O3 with HZSM-5 have been studied for the conversion of C8 aromatics and the aromatization of n-pentane. Hydrogen reduction of the mechanical mixture is a necessary step in the formation of an active catalyst and the reduction process has been characterized by IR spectroscopy. Reduced materials exhibit superior activity and selectivity compared to mechanical mixtures which have not be reduced. 相似文献
84.
Bulanova Marina V. Sidorko Vladislav R. Meleshevich Konstantin A. 《Powder Metallurgy and Metal Ceramics》2004,43(1-2):50-61
A major aspect is considered of the physicochemical interaction in binary systems formed by REM with group IV p elements, namely the phase diagrams. The general regularities and the differences between these phase diagrams are considered for REM – X systems (X = Si, Ge, Sn, and Pb), particularly the relationship between the phase diagram topology and the crystallochemistry of the compounds formed. A comparison is performed for predicted and experimentally constructed phase diagrams. 相似文献
85.
The tremendous success of the World Wide Web is countervailed by efforts needed to search and find relevant information. For tabular structures embedded in HTML documents, typical keyword or link-analysis based search fails. The Semantic Web relies on annotating resources such as documents by means of ontologies and aims to overcome the bottleneck of finding relevant information. Turning the current Web into a Semantic Web requires automatic approaches for annotation since manual approaches will not scale in general. Most efforts have been devoted to automatic generation of ontologies from text, but with quite limited success. However, tabular structures require additional efforts, mainly because understanding of table contents requires the comprehension of the logical structure of the table on the one hand, as well as its semantic interpretation on the other. The focus of this paper is on the automatic transformation and generation of semantic (F-Logic) frames from table-like structures. The presented work consists of a methodology, an accompanying implementation (called TARTAR) and a thorough evaluation. It is based on a grounded cognitive table model which is stepwise instantiated by the methodology. A typical application scenario is the automatic population of ontologies to enable query answering over arbitrary tables (e.g. HTML tables). 相似文献
86.
Vladislav?J.?Kecojevic Marek?J.?Mrugala Radomir?D.?Simic Ranka?M.?StankovicEmail author 《Mine Water and the Environment》2003,22(3):149-154
Abstract.
Drainage systems in large surface mines are designed to
accomplish three basic objectives: keeping working conditions
dry, stable and safe; lowering hydrostatic pressure and
increasing the effective stress of soil to improve slope
stability; and ensuring pit floor workability. This can be
achieved with drainage facilities that include channels, water
collection sumps, and pump stations. We report the development
of a computer-aided system called Dewatering of Open Pit Mines
(DEWOP), which can assist open pit mine designers to solve
water-related problems. The system was developed in a Visual
Basic object programming language, taking advantage of
multi-user, open database connectivity, such as Microsoft
Access, for storage and processing of information. In tests at
coal and copper surface mines, it reduced drainage facilities
costs by 8%. 相似文献
87.
Recordings of spontaneous activity of in vitro neuronal networks reveal various phenomena on different time scales. These include synchronized firing of neurons, bursting
events of firing on both cell and network levels, hierarchies of bursting events, etc. These findings suggest that networks’
natural dynamics are self-regulated to facilitate different processes on intervals in orders of magnitude ranging from fractions
of seconds to hours. Observing these unique structures of recorded time-series give rise to questions regarding the diversity
of the basic elements of the sequences, the information storage capacity of a network and the means of implementing calculations.
Due to the complex temporal nature of the recordings, the proper methods of characterizing and quantifying these dynamics
are on the time–frequency plane. We thus introduce time-series analysis of neuronal network’s synchronized bursting events
applying the wavelet packet decomposition based on the Haar mother-wavelet. We utilize algorithms for optimal tiling of the
time–frequency plane to signify the local and global variations within the sequence. New quantifying observables of regularity
and complexity are identified based on both the homogeneity and diversity of the tiling (Hulata et al., 2004, Physical Review
Letters 92: 198181–198104 ). These observables are demonstrated while exploring the regularity–complexity plane to fulfill
the accepted criteria (yet lacking an operational definition) of Effective Complexity. The presented question regarding the
sequences’ capacity of information is addressed through applying our observables on recorded sequences, scrambled sequences,
artificial sequences produced with similar long-range statistical distributions and on outputs of neuronal models devised
to simulate the unique networks’ dynamics. 相似文献
88.
Vladislav B. Tadić 《Machine Learning》2006,63(2):107-133
The mean-square asymptotic behavior of temporal-difference learning algorithms with constant step-sizes and linear function
approximation is analyzed in this paper. The analysis is carried out for the case of discounted cost function associated with
a Markov chain with a finite dimensional state-space. Under mild conditions, an upper bound for the asymptotic mean-square
error of these algorithms is determined as a function of the step-size. Moreover, under the same assumptions, it is also shown
that this bound is linear in the step size. The main results of the paper are illustrated with examples related to M/G/1 queues and nonlinear AR models with Markov switching.
Editor: Robert Schapire 相似文献
89.
Gibbs free energies, enthalpies, and entropies of formation of the compounds ScFe2 and Sc29Fe6 are found by measuring the emf of galvanic cells in the range 720-1030 K. The nature of interaction in Fe REM binary systems is analyzed. Scandium is shown to behave like a 3d-metal during interaction with iron. 相似文献
90.
The organization of high-performance execution of a fragmented program has encountered with the problem of choosing of an acceptable way of its execution. The potentialities of optimizing the execution at the stages of fragmented program development, compilation and execution are considered. The methods and algorithms of such an optimization are proposed to be included into the LuNA fragmented programming language, compiler, generator and run-time system. 相似文献