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排序方式: 共有174条查询结果,搜索用时 0 毫秒
1.
Lok Kumar Shrestha 《Journal of Dispersion Science and Technology》2013,34(8):1236-1241
We have investigated the phase behavior of diglycerol monomyristate (DGM) in a variety of organic solvents over a wide range of temperatures and compositions. At lower temperature, there exists a surfactant solid, which solubilize different amounts of oils depending on the oil nature. The melting temperature of the solid phase is virtually constant in a wide range of composition. In all the systems, a lamellar liquid crystal (Lα) is formed in surfactant‐rich regions at intermediate temperatures between the solid‐melt and isotropic two‐ or single‐phase regions. In the dilute regions reverse vesicles are formed in the Lα+O regions mainly in the case of linear hydrocarbon type oils. In the aromatic and cyclic aliphatic oils, there are isotropic solutions at 25°C. However, there is dispersion of α‐solid in the case of liner hydrocarbon oils. Two liquid‐phase regions above the Lα phase are observed in the case of tetradecane and hexadecane. In the shorter chain oil systems, such as octane and decane, no two liquid‐phase appear above Lα region. That is the two liquid‐phase region is largely dependent on the chain length of the oils, and becomes wider in longer hydrocarbon oil. 相似文献
2.
An efficient and facile green synthesis of spirooxindole derivatives bearing pyrano[2,3-c]pyrazole moiety has been achieved via a \(\mathrm{CeO}_{2}\)-NPs catalyzed four-component reaction in water. The protocol offers an environmentally benign and effective approach to highly functionalized and biologically interesting spiro[indoline-3,4\(^\prime \)-pyrano[2,3-c]pyrazole] derivatives. The synthesized compounds exhibit potent antioxidant and antibacterial activities. 相似文献
3.
Santosh K. Shrestha Heiko Timmers Aidan P. Byrne Wayne D. Hutchison Don H. Chaplin Rakesh Dogra 《Hyperfine Interactions》2004,158(1-4):407-411
A radioisotope ion implanter has been developed using a cesium-sputtering, negative ion source, which offers versatility and
sustained operation. Employing the molecular 111In16O− ion, μCi activities of the radioisotope probe 111In/Cd have been implanted into different material hosts. The implanted tracer activity has been shown to be sufficient for
LTNO, NMRON and PAC. A new NMRON resonance for 111InAg was observed at 75.08 MHz. In2O3 powder performed well as the radioisotope carrier in the ion source, with the ratio of radioisotope and parasitic ion current
being typically 4 × 10−4. 相似文献
4.
Jiankun Shao Rishav Choudhary David F. Davidson Ronald K. Hanson Samuel Barak Subith Vasu 《Proceedings of the Combustion Institute》2019,37(4):4555-4562
The need for more efficient power cycles has attracted interest in super-critical CO2 (sCO2) cycles. However, the effects of high CO2 dilution on auto-ignition at extremely high pressures has not been studied in depth. As part of the effort to understand oxy-fuel combustion with massive CO2 dilution, we have measured shock tube ignition delay times (IDT) for methane/O2/CO2 mixtures and hydrogen/O2/CO2 mixtures using sidewall pressure and OH* emission near 306?nm. Ignition delay time was measured in two different facilities behind reflected shock waves over a range of temperatures, 1045–1578?K, in different pressures and mixture regimes, i.e., CH4/O2/CO2 mixtures at 27–286 atm and H2/O2/CO2 mixtures at 37–311 atm. The measured data were compared with the predictions of two recent kinetics models. Fair agreement was found between model and experiment over most of the operating conditions studied. For those conditions where kinetic models fail, the current ignition delay time measurements provide useful target data for development and validation of the mechanisms. 相似文献
5.
Séan J. Cassady Rishav Choudhary Vivek Boddapati Nicolas H. Pinkowski David F. Davidson Ronald K. Hanson 《国际化学动力学杂志》2020,52(11):725-738
The pyrolysis of propane plays an important role in determining the combustion properties of natural gas mixtures and offers insight into the cracking patterns of larger fuels. This work investigates propane pyrolysis behind reflected shock waves with a multiwavelength laser-absorption speciation technique. Nine laser wavelengths, sensitive to key pyrolysis species, were used to measure absorbance time histories during the decomposition of 2% propane in argon between 1022 and 1467 K, 3.7-4.3 atm. Absorbance models were developed at each diagnostic wavelength to interrogate common initial conditions, and time histories of all major species are reported at 1250, 1290, 1330, 1370, and 1410 K. Nearly complete carbon recovery observed at lower temperatures enabled the inference of hydrogen formation from atomic conservation, while decaying carbon recovery at high temperatures suggests the formation of allene and 1-butene. The results show systematically faster pyrolysis than predicted by kinetic modeling and motivate further study into the kinetics of propane pyrolysis. 相似文献
6.
7.
Jan L. Allen Bria A. Crear Rishav Choudhury Michael J. Wang Dat T. Tran Lin Ma Philip M. Piccoli Jeff Sakamoto Jeff Wolfenstine 《Molecules (Basel, Switzerland)》2021,26(9)
Spinel-structured solids were studied to understand if fast Li+ ion conduction can be achieved with Li occupying multiple crystallographic sites of the structure to form a “Li-stuffed” spinel, and if the concept is applicable to prepare a high mixed electronic-ionic conductive, electrochemically active solid solution of the Li+ stuffed spinel with spinel-structured Li-ion battery electrodes. This could enable a single-phase fully solid electrode eliminating multi-phase interface incompatibility and impedance commonly observed in multi-phase solid electrolyte–cathode composites. Materials of composition Li1.25M(III)0.25TiO4, M(III) = Cr or Al were prepared through solid-state methods. The room-temperature bulk Li+-ion conductivity is 1.63 × 10−4 S cm−1 for the composition Li1.25Cr0.25Ti1.5O4. Addition of Li3BO3 (LBO) increases ionic and electronic conductivity reaching a bulk Li+ ion conductivity averaging 6.8 × 10−4 S cm−1, a total Li-ion conductivity averaging 4.2 × 10−4 S cm−1, and electronic conductivity averaging 3.8 × 10−4 S cm−1 for the composition Li1.25Cr0.25Ti1.5O4 with 1 wt. % LBO. An electrochemically active solid solution of Li1.25Cr0.25Mn1.5O4 and LiNi0.5Mn1.5O4 was prepared. This work proves that Li-stuffed spinels can achieve fast Li-ion conduction and that the concept is potentially useful to enable a single-phase fully solid electrode without interphase impedance. 相似文献
8.
Bruch’s membrane is a layer composed of collagen fibers located just beneath the retina. This study validates a strategy used
to map the morphological and adhesion characteristics of collagen fibers in Bruch’s membrane. Atomic force microscopy tips
were functionalized with different chemical groups and used to map the hydrophilic and hydrophobic regions on the surface
of the eye tissue. The largest adhesion forces were observed when tips functionalized with NH2 groups were used. The trend in the adhesion forces was rationalized based on the distribution of different functional groups
in the triple-helical structure of the collagen fibers. The results of this study can be used to design more effective strategies
to treat eye diseases such as age-related macular degeneration. 相似文献
9.
Simulation of winter air pollution dispersion mechanism of Kathmandu valley by water-tank experiment
Shrestha?M.?L.?Email author Kaga?A. Kondo?A. Inoue?Y. Sugisawa?M. Sapkota?B. 《显形杂志》2004,7(4):317-329
The air pollution concentration in Kathmandu valley in the winter season was found to be higher than in the summer season
due to the formation of the inversion layer. This mechanism was simulated in the water-tank experiment by measuring the temperature
and flow field using liquid crystal thermometry and particle image velocimetry. Thermal stratification was made at the beginning
of the experiment and the surface temperature of the valley model was changed with 12 minutes period matching the diurnal
field temperature pattern of the Kathmandu valley. The updraft wind and Bernard convection occurred during daytime and downdraft
wind and inversion layer were realized during nighttime. The temperature, flow field and mass dispersion characteristics obtained
in the water-tank experiment explained clearly the mechanism of air pollution in Kathmandu valley. 相似文献
10.
Because Nitrosomonas europaea contains ammonia-oxidizing enzyme, nitrite reductase, and nitrous oxide reductase, the conversion of ammonia to dinitrogen
was tried with different reaction conditions. In aerobic reaction conditions, ammonium was converted to nitrite (NO
2
−
), while under oxygen-limiting or oxygen-free conditions, NO
2
−
-N formed from ammonia oxidation by N. europaea was reduced to N2O and dinitrogen with 22% conversion. During denitrification, optimal pH for the production of N2O and dinitrogen was found to be 7.0–8.0. Dinitrogen was not produced in acidic pH<7.0. A low partial oxygen pressure as well
as oxygen-free conditions are favorable for high production of dinitrogen. 相似文献