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排序方式: 共有213条查询结果,搜索用时 15 毫秒
71.
A Unified Sensor Architecture for Isothermal Detection of Double‐Stranded DNA,Oligonucleotides, and Small Molecules
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Miha Drofenik Irena Ban Darko Makovec Andrej Žnidaršič Zvonko Jagličić Darko Hanžel Darja Lisjak 《Materials Chemistry and Physics》2011
Superparamagnetic Ba-hexaferrite nanoparticles were prepared using modified hydrothermal synthesis. The precursor and hydroxide [OH−] concentrations were optimized and the synthesis temperature and time were drastically reduced. The size and the morphology of synthesized nanoparticles was confirmed by transmission electron microscopy (TEM) images. The crystal structure of the nanoparticles was characterized by X-ray diffraction data. Powders synthesized at 160 °C exhibit a bimodal particle size distribution while those synthesized at TS = 150 °C show a monomodal particle size distribution. Zero-field-cooling (ZFC) and field-cooling (FC) magnetization measurements were performed using a superconducting quantum interference device magnetometer from 2 to 300 K to investigate the magnetic properties of nanoparticles. The FC/ZFC magnetization measurements showed a typical superparamagnetic behavior. The synthesized superparamagnetic particles exhibit a disc-like shape, in average 11 nm wide and 3 nm thick with a room temperature magnetization of approximately 10 Am2/kg at 5 T. 相似文献
74.
Candy Ann Dwamena Darkwa Anthony Andrews Stephen Akosah Darko George Asare 《International Journal of Applied Ceramic Technology》2023,20(3):1730-1739
A large quantity of water treatment sludge (WTS) is generated yearly from Ghana's Weija water treatment plant. The sludge contains some heavy metals and other toxic chemicals, which must be managed to minimize environmental impact. In the current work, WTS was mixed with varying quantities of kaolinitic-based clays (kaolin and lithomargic clays) to produce porous mullite-based bricks. The bricks were fired at 1200°C for 1 h, and their properties were determined. Lithomargic clay-based mixtures had less dimensional variation and were suitable to produce near-net shape bricks compared to WTS-based bricks. The addition of WTS increased the linear firing shrinkage and apparent porosity whilst decreasing bulk density and compressive strength. Porous mullite-based bricks fabricated from lithomargic clay exhibited high compressive strength (6.3 MPa) at 10 wt.% WTS addition. The highest apparent porosity of 27% was attained at 40 wt.% WTS addition with compressive strength of 5.1 MPa and thermal conductivity of .5 W/m K. 相似文献
75.
Darko Bosnakovski David Oyler Ana Mitanoska Madison Douglas Elizabeth T. Ener Ahmed S. Shams Michael Kyba 《International journal of molecular sciences》2022,23(4)
FSHD is caused by loss of silencing of the DUX4 gene, but the DUX4 protein has not yet been directly detected immunohistologically in affected muscle, raising the possibility that DUX4 expression may occur at time points prior to obtaining adult biopsies for analysis, with consequent perturbations of muscle being responsible for disease progression. To test the extent to which muscle can regenerate following DUX4-mediated degeneration, we employed an animal model with reversible DUX4 expression, the iDUX4pA;HSA mouse. We find that muscle histology does recover substantially after DUX4 expression is switched off, with the extent of recovery correlating inversely with the duration of prior DUX4 expression. However, despite fairly normal muscle histology, and recovery of most cytological parameters, the fibroadipogenic progenitor compartment, which is significantly elevated during bouts of fiber-specific DUX4 expression, does not return to basal levels, even many weeks after a single burst of DUX4 expression. We find that muscle that has recovered from a DUX4 burst acquires a propensity for severe fibrosis, which can be revealed by subsequent cardiotoxin injuries. These results suggest that a past history of DUX4 expression leads to maintained pro-fibrotic alterations in the cellular physiology of muscle, with potential implications for therapeutic approaches. 相似文献
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77.
Extended defects in ZnO ceramics containing, 6 wt% Bi4 Ti3 O12 were studied by analytical electron microscopy. Apart from basal plane condensation stacking faults, which are also present in as-received ZnO, extended defects related to the presence of Bi4 Ti3 O12 were observed. In samples sintered at 900°C they lie in the basal or in the prismatic planes and they quite often form closed loops, whereas they form serpentine-shaped boundaries in samples sintered at 1200°C. Evidence is given that they are inversion boundaries. Their TEM image characteristics, as well as the unambiguous presence of Ti at the boundaries, suggest that they are formed due to the presence of 2-D coherent precipitates of Ti-rich (possibly Zn2 TiO4 -type spinel) phase. 相似文献
78.
Darko Grujicic 《Electrochimica acta》2006,51(13):2678-2690
Reaction and nucleation mechanisms of nickel in ammoniacal solutions have been investigated as a function of nickel concentration, solution pH, deposition potential, temperature and conditioning potential. Electrochemical mechanisms of nickel reduction were found to be pH dependent, while their kinetics was concentration dependent. A surface film formed by anodic oxidation passivates nickel clusters preventing their further oxidation. Nickel nucleation on vitreous carbon, which proceeds according to the progressive nucleation model, shows a large degree of inhibition at both pH 6 and pH 9. Cluster sizes were larger when electrodeposition was carried out from solutions with higher nickel concentrations. The clusters were also larger at more negative deposition potentials and at higher solution pH. Cluster population density increased with the increasing solution temperature. Different activation energies for the nickel-aquo and nickel-ammino complexes calculated from Arrhenius diagram indicate that electroreduction of nickel-ammino complex is energetically more demanding. All electrochemical results were further verified by the atomic force microscopy investigations. 相似文献
79.
Antolii Belous Oleg V’yunov Maya Glinchuk Valentin Laguta Darko Makovez 《Journal of Materials Science》2008,43(9):3320-3326
Barium titanate, which is characterized by a positive temperature coefficient of resistance (PTCR), is widely used in practice.
At the same time, it is unknown why only a small percentage of the introduced donor dopant takes part in the formation of
PTCR effect, which phases appear at grain boundaries, how the introduced acceptor dopants affect the properties of grains.
Elucidation of the above questions is of considerable scientific and practical interest. It has been shown that the phases
Bа6Ti17O40 and Y2Ti2O7 precipitate on grains of barium titanate doped with donor dopant (yttrium). We identified paramagnetic impurities (iron, manganese,
chromium) in starting reagents. These impurities can occupy titanium sites. Therefore, the part of the donor dopant that is
spent on the charge exchange of acceptor dopants does not participate in the charge exchange of titanium Ti4+ → Ti3+, which is responsible for the appearance of PTCR effect in barium titanate. It has been found that an extra acceptor dopant
(manganese) is distributed mainly at grain boundaries and in the grain outer layer. It has been shown that manganese ions
introduced additionally (as acceptor dopants) increase the potential barrier at grain boundaries and form a high-resistance
outer layer in PTCR ceramics. The resistance of grains, outer layers, and grain boundaries as a function of the manganese
content has been investigated.
相似文献
Oleg V’yunovEmail: |
80.
Gelatin sensitized with tot'hema and eosin (compounds used in medical therapy) appears to be an excellent material for microlens fabrication. Lenses are produced by irradiation with a 532 nm laser beam. Aspheric concave lenses are formed rapidly with low power radiation. The lens profile is analyzed, as well as imaging properties. Physics of lens formation is also proposed. All material constituents are nonpoisonous, resulting in an environmentally safe, low toxicity material. 相似文献