نتایج جستجو برای: hydride
تعداد نتایج: 5067 فیلتر نتایج به سال:
The mechanism of volatile hydride generation (HG) and the formation of analyte atoms in the quartz cell atomizer used in the determination of hydride-forming elements (As, Bi, Ge, Pb, Sb, Sn, Te etc.) by atomic absorption spectrometry (AAS), have been critically reviewed. The nascent hydrogen mechanism failed to explain hydride generation under different experimental conditions when tetrahydrob...
This thesis studies a hybrid PEM fuel cell system for use in low power, long life sensor networks. PEM fuel cells offer high efficiency and environmental friendliness but have not been widely adopted due to cost, reliability, and the problem of hydrogen storage. This thesis focuses on the problem of hydrogen storage. Lithium hydride is selected for study because of its high hydrogen content and...
KOH-based electrolytes with different salt additives were investigated to reduce their corrosive nature toward Mg/Ni metal hydride alloys used as negative electrodes in nickel metal hydride (Ni/MH) batteries. Alkaline metal halide salts and oxyacid salts were studied as additives to the traditional KOH electrolyte with concentrations varying from 0.005 M to 1.77 M. Effects of the cations and an...
Magnesium hydride is cheap and contains 7.7 wt % hydrogen, making it one of the most attractive hydrogen storage materials. However, thermodynamics dictate that hydrogen desorption from bulk magnesium hydride only takes place at or above 300 degrees C, which is a major impediment for practical application. A few results in the literature, related to disordered materials and very thin layers, in...
It is observed that large quantities of hydrogen (H2) are released at ambient temperatures during the mechano-chemical synthesis of the Li-Al-N-Mg-based hydride composites using an energetic ball milling in a unique magneto-mill. For the (nLiAlH4+LiNH2; n=1, 3, 11.5, 30) composite, at the molar ratio n=1, the LiNH2 constituent destabilizes LiAlH4 and enhances its decomposition to Li3AlH6, Al an...
Aqueous hydride transfer is a fundamental step in emerging alternative energy transformations such as H2 evolution and CO2 reduction. "Hydricity," the hydride donor ability of a species, is a key metric for understanding transition metal hydride reactivity, but comprehensive studies of aqueous hydricity are scarce. An extensive and self-consistent aqueous hydricity scale is constructed for a fa...
Dihydrofolate reductase has long been used as a model system to study the coupling of protein motions to enzymatic hydride transfer. By studying environmental effects on hydride transfer in dihydrofolate reductase (DHFR) from the cold-adapted bacterium Moritella profunda (MpDHFR) and comparing the flexibility of this enzyme to that of DHFR from Escherichia coli (EcDHFR), we demonstrate that fac...
Directed Energy Weapon (DEW) systems in a pulse operation mode dissipate excessively large, transient waste heat because of their inherent inefficiencies. The heat storage system can store such a pulsed heat load not relying on oversized systems and dissipate the stored heat over time after the pulse operation. A compressor-driven metal hydride heat storage system was developed for efficient, c...
The ring opening of 2-substituted N,N-dibenzylaziridinium ions by bromide exclusively occurs at the substituted aziridine carbon atom in a stereospecific way, whereas the opposite regioselectivity was observed for hydride-induced ring opening at the unsubstituted position; furthermore, this unprecedented hydride-promoted reactivity was validated by means of Density Functional Theory (DFT) calcu...
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