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排序方式: 共有231条查询结果,搜索用时 187 毫秒
111.
Alena Michalcová Dalibor VojtěchJakub ?í?ek Ivan ProcházkaJan Drahokoupil Pavel Novák 《Journal of Alloys and Compounds》2011,509(7):3211-3218
Positron annihilation spectroscopy was employed for the microstructure characterization of rapidly solidified Al-3 wt.% Cr-3 wt.% Fe-0.8 wt.% Ce alloy prepared by melt spinning. Results of the positron annihilation study are analyzed within the diffusion trapping model and compared with results of X-ray diffraction, transmission electron microscopy and microhardness measurements. A good consistency among all experimental techniques was obtained. The rapidly solidified alloy exhibits ultra fine grained structure, consisting of cells separated by dislocation walls. Annealed samples showed no significant changes in structure up to 400 °C which proves good thermal stability of ultra fine grained structure. Exposure of the sample to temperature of 500 °C caused significant changes in the material. 相似文献
112.
Lopareva-Pohu A Pourrut B Waterlot C Garçon G Bidar G Pruvot C Shirali P Douay F 《The Science of the total environment》2011,409(3):647-654
Sustainable management of large surface areas contaminated with trace elements is a real challenge, since currently applied remediation techniques are too expensive for these areas. Aided phytostabilisation appears to be a cost efficient technique to reduce metal mobility in contaminated soils and contaminated particle spread. In this context, this study aimed at evaluating the long-term efficiency of aided phytostabilisation on former agricultural soils highly contaminated with trace elements. The influence of afforestation and fly ash amendments to reduce metal mobility was investigated. Before being planted with a tree mix, the study site was divided into three plots: a reference plot with no amendment, the second amended with silico-aluminous fly ash and the third with sulfo-calcic fly ash. After eight years, some soil physico-chemical parameters, including cadmium (Cd), lead (Pb) and zinc (Zn) extractability were modified. In particular, pH decreased on the whole site while organic carbon content increased. The alteration of these parameters influencing trace element mobility is explained by afforestation. Over time, concentrations of CaCl2-extractable metals increased and were correlated with the soil pH decrease. In the amended soils, extractable Cd, Pb and Zn concentrations were lower than in the reference soil. The results indicated that the two fly ashes buffered natural soil acidification due to vegetation development and limited trace element mobility and thus could limit their bioavailability. For long-term phytostabilisation, special attention should be focused on the soil pH, metal mobility and phytoavailability analysis. 相似文献
113.
Alena Reznickova Zdenka Novotna Nikola Slepickova Kasalkova Vaclav Svorcik 《Nanoscale research letters》2013,8(1):252
Properties of gold films sputtered under different conditions onto borosilicate glass substrate were studied. Mean thickness of sputtered gold film was measured by gravimetry, and film contact angle was determined by goniometry. Surface morphology was examined by atomic force microscopy, and electrical sheet resistance was determined by two-point technique. The samples were seeded with rat vascular smooth muscle cells, and their adhesion and proliferation were studied. Gold depositions lead to dramatical changes in the surface morphology and roughness in comparison to pristine substrate. For sputtered gold structures, the rapid decline of the sheet resistance appears on structures deposited for the times above 100 s. The thickness of deposited gold nanoparticles/layer is an increasing function of sputtering time and current. AFM images prove the creation of separated gold islands in the initial deposition phase and a continuous gold coverage for longer deposition times. Gold deposition has a positive effect on the proliferation of vascular smooth muscle cells. Largest number of cells was observed on sample sputtered with gold for 20 s and at the discharge current of 40 mA. This sample exhibits lowest contact angle, low relative roughness, and only mild increase of electrical conductivity. 相似文献
114.
DNase I Induces Other Endonucleases in Kidney Tubular Epithelial Cells by Its DNA-Degrading Activity
Tariq Fahmi Xiaoying Wang Dmitry D. Zhdanov Intisar Islam Eugene O. Apostolov Alena V. Savenka Alexei G. Basnakian 《International journal of molecular sciences》2020,21(22)
Endonuclease-mediated DNA fragmentation is both an immediate cause and a result of apoptosis and of all other types of irreversible cell death after injury. It is produced by nine enzymes including DNase I, DNase 2, their homologs, caspase-activated DNase (CAD) and endonuclease G (EndoG). The endonucleases act simultaneously during cell death; however, regulatory links between these enzymes have not been established. We hypothesized that DNase I, the most abundant of endonucleases, may regulate other endonucleases. To test this hypothesis, rat kidney tubular epithelial NRK-52E cells were transfected with the DNase I gene or its inactive mutant in a pECFP expression vector, while control cells were transfected with the empty vector. mRNA expression of all nine endonucleases was studied using real-time RT-PCR; DNA strand breaks in endonuclease genes were determined by PCR and protein expression of the enzymes was measured by Western blotting and quantitative immunocytochemistry. Our data showed that DNase I, but not its inactive mutant, induces all other endonucleases at varying time periods after transfection, causes DNA breaks in endonuclease genes, and elevates protein expression of several endonucleases. This is the first evidence that endonucleases seem to be induced by the DNA-degrading activity of DNase I. 相似文献
115.
Ethik in der Medizin - 相似文献
116.
117.
Carsten Schroer Juergen Konys Jordi Abellà Alena Kobzova Jean-Louis Courouau 《Journal of Nuclear Materials》2011,415(3):338-347
Electrochemical oxygen sensors currently used for measuring the chemical potential of oxygen in liquid lead alloys were investigated by five European laboratories, focussing on factors influencing the accuracy of the sensor output, the long-term performance in experimental facilities and methods of testing the sensors before installation and during operation in a plant. The design of different electrochemical oxygen sensors is introduced, along with the experimentally determined sensor reliability and appropriate testing methods. The reported results summarize the results of Task 4.2.4 within Domain 4 (DEMETRA) of the integrated project (IP) EUROTRANS that was funded by the EURATOM 6th Framework Programme. 相似文献
118.
Barbora Slezáková Kevin Matzick Alena Komersová Václav Lochař Martin Bartoš Jitka Mužíková Samir Haddouchi 《European Journal of Lipid Science and Technology》2021,123(5):2000235
This study is focused on the use of glyceryl behenate as a lipophilic excipient of matrix tablets providing controlled drug release. The aim of this study is to evaluate activation energy (EA) and changes of the thermodynamic parameters (ΔH, ΔS, ΔG) of a dissolution process. These values, which have not yet been published, can lead to better understanding of a drug release mechanism and can extend the use options of glyceryl behenate in the pharmaceutical industry. Values of ΔH, ΔS, ΔG and EA, providing an overall thermodynamic view on the studied matrix tablets, are evaluated based on the temperature-dependences of the release rate constant of a model drug (temperature range 25 - 45 °C). The studied lipophilic matrix tablets contain 10% to 50% of glyceryl behenate. Dissolution testing is carried out in an aqueous solution of HCl with addition of NaCl (pH1.2). Positive values of ΔH in the range of 3.83 to 56.13 kJ mol-1 and positive values of ΔG indicate that the dissolution of the studied glyceryl behenate matrix tablets is an endothermic process which does not proceed spontaneously (in a temperature range of 25 - 45 °C). The negative slope of the linear curves of enthalpy-entropy compensation confirms the entropy-driven dissolution. Practical Applications : A better understanding of the dissolution process is an important aspect, e.g., in the field of drug formulation strategy. In this study, it is confirmed that the influence of temperature on the model drug release rate is negligible for tablets containing more than 40% of glyceryl behenate. It is an important result for drug design due to the reduction of risk of a possible dose dumping effect induced by temperature and the prevention of in vivo therapeutic failure. 相似文献
119.
Ivone Cristina Igreja S Katarina Tripska Milos Hroch Radomir Hyspler Alena Ticha Hana Lastuvkova Jolana Schreiberova Eva Dolezelova Samira Eissazadeh Barbora Vitverova Iveta Najmanova Martina Vasinova Miguel Pericacho Stanislav Micuda Petr Nachtigal 《International journal of molecular sciences》2020,21(23)
120.