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81.
We have investigated the electrocaloric (EC) properties of the ceramic 0.7Pb(Mg1/3Nb2/3)O3–0.3PbTiO3. A variety of samples with different median grain sizes, i.e., 1.0, 2.2 and 4.0?μm, and relative densities of about 96% were prepared using atmospheric sintering at 1200oC for 2, 8 and 16?h. The ceramic material with a median grain size of 2.2?μm exhibited the highest value for the EC temperature change, i.e., 1.27?K at 60?kV?cm?1, measured with a high-resolution calorimeter. This value is 25 and 19% higher than the value for the ceramics with the finer and the coarser grains, respectively. 相似文献
82.
Renáta Vadkertiová Hana Dudášová Eva Stratilová Marta Balaščáková 《Yeast (Chichester, England)》2019,36(10):617-631
Yeasts are common constituents of different types of soil. Their diversity depends on the season, the type and depth of the soil, the plant species, and the locality. In this study, diversity of yeasts isolated from the soil adjacent to five fruit trees (apple, appricot, peach, pear, and plum) in two localities (in Slovakia) in four sampling periods was examined. Our results demonstrated differences in the species richness and evenness among the yeast populations, which inhabited the soil beneath individual fruit tree species in both localities. Altogether, 32 ascomycetous and 27 basidiomycetous yeast species were discovered. The highest species richness was found in the soil adjacent to the apricot trees. Galactomyces candidum, Metschnikowia pulcherrima, Hanseniaspora uvarum, Schwanniomyces capriottii, and Tausonia pullulans, as well as the genus Apiotrichum, were present in soil samples in all samplings. Two species of the genus Holtermanniella (H. festucosa and H. takashimae) were exclusively isolated during Sampling IV in April. Cyberlindnera spp., Clavispora reshetovae, S. capriottii, and Trichosporon asahii were found only in one of two localities. Ascomycetous yeasts were present more frequently than their basidiomycetous counterparts in the three samplings (one in June and two in October); they formed from 65.6% to 70.8% of the total yeast population, whereas basidiomycetous yeasts prevailed in the April sampling (61.2%). 相似文献
83.
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85.
Eltai Nahla O. Mahmoud Nouf N. Zakaria Zain Z. Abdelrahman Hana Moustafa Ala-Eddin Al Al-Asmakh Maha 《Journal of Inorganic and Organometallic Polymers and Materials》2022,32(7):2527-2537
Journal of Inorganic and Organometallic Polymers and Materials - Gold nanorods (AuNRs) were synthesized by the seed-mediated wet chemical method using a binary surfactant system. AuNRs were... 相似文献
86.
Chemical Synthesis,Sintering and Piezoelectric Properties of Ba0.85Ca0.15 Zr0.1Ti0.9O3 Lead‐Free Ceramics 下载免费PDF全文
Klara Castkova Karel Maca Jaroslav Cihlar Hana Hughes Ales Matousek Pavel Tofel Yang Bai Tim W. Button 《Journal of the American Ceramic Society》2015,98(8):2373-2380
The preparation of Ba0.85Ca0.15 Zr0.1Ti0.9O3 (BCZT) powders by wet chemical methods has been investigated, and the powders used to explore relationships between the microstructure and piezoelectric properties (d33 coefficient) of sintered BCZT ceramics. Sol–gel synthesis has been shown to be a successful method for the preparation of BCZT nanopowders with a pure tetragonal perovskite phase structure, specific surface area up to 21.8 m2/g and a mean particle size of 48 nm. These powders were suitable for the fabrication of dense BCZT ceramics with fine‐grain microstructures. The ceramics with the highest density of 95% theoretical density (TD) and grain size of 1.3 μm were prepared by uniaxial pressing followed by a two‐step sintering approach which contributed to the refinement of the BCTZ microstructure. A decrease in the grain size to 0.8–0.9 μm was achieved when samples were prepared using cold isostatic pressing. Using various sintering schedules, BCZT ceramics with broad range of grain sizes (0.8–60.5 μm) were prepared. The highest d33 = 410.8 ± 13.2 pC/N was exhibited by ceramics prepared from sol–gel powder sintered at 1425°C, with the relative density of 89.6%TD and grain size of 36 μm. 相似文献
87.
Martin Hruby Jan Kucka Hana Mackova Cestmir Konak Miroslav Vetrik Jan Kozempel Ondrej Lebeda 《应用聚合物科学杂志》2009,111(5):2220-2228
Radiolabeled thermoresponsive polymers (TRPs) with cloud‐point temperatures between room temperature and body temperature may have an advantage for local radiotherapeutical applications because TRPs may be isotopically labeled in solution at room temperature and injected as a solution, and at the site of application, the polymers form a depo because of phase separation at body temperature. A new polymeric drug‐delivery system designed for combined local chemoradiotherapy with an injectable TRP bearing a radionuclide and the hydrophobic moiety doxorubicin (DOX) was synthesized and characterized. In the system, DOX served as an antiproliferative agent with known synergic effects with ionizing radiation and the hydrophobic moiety controlling bioerosion and elimination of the system at the same time. DOX was bound to the polymer carrier by a hydrolytically labile N‐glycosylamine bond. Hydrolysis of the N‐glycosylamine bond thus controlled the DOX release and dissolution of the system in the model aqueous milieu. DOX was slowly released during incubation in aqueous milieu at 37°C, which caused complete dissolution of the bioerodable polymer within about 2 weeks. The model radionuclide iodine 125, bound to a small amount of poly(N‐isopropylacrylamide‐co‐N‐methacryloyl tyrosinamide), was retained in the separated phase and also slowly dissolved during the incubation. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
88.
Takeo M Prabu SK Kitamura C Hirai M Takahashi H Kato D Negoro S 《Journal of Bioscience and Bioengineering》2006,102(4):352-361
Alkylphenols (APs) are ubiquitous contaminants in aquatic environments and have endocrine disrupting and toxic effects on aquatic organisms. To investigate biodegradation mechanisms of APs, an AP degradation gene cluster was cloned from a butylphenol (BP)-degrading bacterium, Pseudomonas putida MT4. The gene cluster consisted of 13 genes named bupBA1A2A3A4A5A6CEHIFG. From the nucleotide sequences, bupA1A2A3A4A5A6 were predicted to encode a multicomponent phenol hydroxylase (PH), whereas bupBCEHIFG were expected to encode meta-cleavage pathway enzymes. A partial sequence of a putative NtrC-type regulatory gene, bupR, was also found upstream of the gene bupB. This result indicates that APs can be initially oxidized into alkylcatechols (ACs), followed by the meta-cleavage of the aromatic rings. To confirm this pathway, AP degradation tests were carried out using the recombinant P. putida KT2440 harboring the PH genes (bupA1A2A3A4A5A6). The recombinant strain oxidized 4-n-APs with an alkyl chain of up to C7 (< or = C7) efficiently and also several BPs including those with an alkyl chain with some degree of branching. Therefore, it was found that PH had a broad substrate specificity for APs with a medium-length alkyl chain (C3-C7). Moreover, the cell extract of a recombinant Escherichia coli harboring bupB (a catechol 2,3-dioxygenase gene) converted 4-n-ACs with an alkyl chain of < or = C9 into yellow meta-cleavage products with a maximum absorbance at 379 nm, indicating that the second step enzyme in this pathway is also responsible for the degradation of ACs with a medium-length alkyl chain. These results suggest that MT4 is a very useful strain in the biodegradation of a wide range of APs with a medium-length alkyl chain, which known nonylphenol-degrading Sphingomonas strains have never degraded. 相似文献
89.
The paper deals with the influence of the electric bias field on the ultrasound velocity of various samples of Pb(Zr
x
Ti1−x
)O3 (PZT) ceramics. The ultrasonic velocities were measured on commercial types of PZT ceramics as APC 841, APC 850, and APC
856, at room temperature. The comparison of the ultrasound velocities dependence on electric bias field was made for poled/unpoled
soft ceramics. The ultrasonic pulse-echo technique was used in our experiment. The ultrasonic system is based on Matec Instruments,
Inc. modules. The time domain response was recorded and time of flight between echoes was directly measured by digital oscilloscope,
type Agilent 54622D. The high bias field was applied on disk samples by the high voltage amplifier type Trek 610D, using a
special setup and sample holder. The sound velocity was found to change drastically near the coercive field for a PZT ceramics,
where the velocity of longitudinal waves decreases with an increasing field while the velocity of shear waves increases, which
is caused by the change of the elastic anisotropy under influence of the depolarization field. The consequent change of the
piezoelectric contribution to effective elastic constant decreases the velocity of longitudinal waves and at the same time
increases the velocity of shear waves around the coercive field. 相似文献
90.
Hana Kopackova Karel Michalek Karel Cejna 《Universal Access in the Information Society》2010,9(1):51-61
This article focuses on the accessibility of local e-government web pages. Accessibility is herein considered in a broader
perspective, taking also into account that information must be findable within the Internet through conventional fulltext
search engines. Based on this assumption, an analysis of 39 local e-government websites in the Czech Republic was carried
out in two testing periods (March 2006 and April 2008). The web pages were analysed both from a citizen’s point of view (with
disadvantage due to disability or to technical equipment) and from the point of view of fulltext search engines. In the analysis
of results, there is an overall evaluation and comparison between testing periods and recommendations for improvement of the
current conditions. 相似文献