نتایج جستجو برای: alkali metal
تعداد نتایج: 210259 فیلتر نتایج به سال:
By the use as tracers of 42K, 86Rb and 32P it has been shown that in the metabolism of Bact. lactis aerogenes (а) the alkali-metal ion enters the cell during oxidation of the carbon substrate (glucose, succinic acid, acetic acid), whether or not a nitrogen source is provided, so that growth occurs; in either event the alkali-metal ion subsequently leaves the cell again; (б) if the pH is lowered...
We present a detailed theoretical analysis of the noble-gas nuclear spin relaxation due to the anisotropic magnetic-dipole hyperfine interaction between the noble-gas nucleus and alkali-metal valence electron vis à vis the already well-understood (spin-conserving) isotropic magnetic-dipole hyperfine interaction in alkali-metal–noble-gas systems. We find that, for all pairs in which the noblegas...
Alkali metal triphenylsilyls [Li(12-crown-4)SiPh3]·(thf)0.5 (2), [Na(15-crown-5)SiPh3]·(thf)0.5 (3) and [K(18-crown-6)SiPh3(thf)] (4) were synthesized using 1,1,1-trimethyl-2,2,2-triphenyldisilane (Ph3SiSiMe3) and isolated in high yields. Solid state structures were determined by single crystal X-ray diffraction. These alkali metal silyls catalyzed the regioselective hydrosilylation of 1,1-diph...
I[I. Place of co-transport with Na ÷ . . . . . . . . . . . . . . . . . . . . . . . . . 489 A. Must the energy for Na+-dependent, uphill amino acid transport be channeled through alkali-metal gradients? . . . . . . . . . . . . . . . . . . . . . . . . . . . 489 B. Attempts to eliminate experimentally the alkali-metal ion gradients without dissipating other forms of transport-related energy storag...
Direct irradiation of atropisomeric α-substituted acrylanilides in the presence of alkali metal ions gave high ee values in the 3,4-dihydro-2-quinolin-2-one photoproduct, while in the absence of alkali metal ions, racemic photoproduct was observed. The heavy atom effect leading to enhanced triplet yields alters the reactive pathway leading to the observed enantioselectivity in the photoproduct.
The first addition of alcohols to carbodiimides catalyzed by transition-metal-free compounds employs 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) and its alkali metal salts. Isoureas are obtained in short reaction times and high yields when TBDK is used as the catalyst. Control of the coordination sphere of potassium with exogenous chelating ligands, in combination with mechanistic DFT calculation...
Synthesis and cation selectivity of 25, 27, dipropoxy-26, 28, Di-propoxy 5, 11, 17, 23, ptert-butyl Calix[4]arene are studied in acetonitrile solution. The stability constants of differentcomplexes of Calixarene (as a ligand) with alkali metal cations are determined at 25 °C by usingspectrophotometric technique.On the basis of calculations, complexation of Calixarene with Cs+and Li+ are more fa...
Electrochemical properties of A(2)MnPO(4)F (A = Na/Li) were investigated both experimentally and with first principles calculations. A new Li(2)MnPO(4)F phase was successfully synthesized for the first time. A one alkali metal ion reaction occurred reversibly within a reasonable voltage window and a two alkali metal ion reaction took place at higher voltages.
Alkali metal doping is essential to achieve highly efficient energy conversion in Cu(In,Ga)Se2 (CIGSe) solar cells. Doping is normally achieved through solid state reactions, but recent observations of gas-phase alkali transport in the kesterite sulfide (Cu2ZnSnS4) system (re)open the way to a novel gas-phase doping strategy. However, the current understanding of gas-phase alkali transport is v...
Phosphine is conformationally stable because of the high inversion energy barrier of the phosphorus atom, which allows the phosphorus atom to become a chiral center. Thus, enantiopure P-stereogenic 12-, 15-, 18-, and 21-membered aliphatic phosphines "diphosphacrowns" were synthesized from secondary P-stereogenic bisphosphine as a chiral building block. Their complexation behaviors with alkali m...
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