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991.
Electrochemical studies of the effect of lanthanide ions on the activity of glutamate dehydrogenase 总被引:6,自引:0,他引:6
Using the electrochemical method based on the "diffusion" layer concept of the convective system, the effect of lanthanide ions La3+ and Eu3+ on the activity of glutamate dehydrogenase (GLDH) has been determined. In suitable concentrations, the lanthanide ions La3+ and Eu3+ can activate the GLDH in the reductive amination of alpha-Ketoglutarate (alpha-KG). The activation mechanism would be that the lanthanide ions could interrupt the binding of NAD+ to GLDH by combining preferentially to NAD+. This mechanism was proposed by the voltammetric studies. 相似文献
992.
Bubble plumes of various void fractions and sizes were produced by varying the flow velocity of a water jet impinging normally on a water surface. The bubbles entrained at the surface were carried downwards by the fluid flow to depths ranging from 33 to 65 cm, and formed roughly cylindrical plumes with diameters ranging from 12 to 27 cm. The acoustic emissions from the plumes were recorded onto digital audio tape using a hydrophone placed outside the cloud at distances ranging from 50 cm to 16.0 m. Closeup video images of the individual bubbles within the plume were also taken in order to gain knowledge of the bubble size distributions. The experiments were performed in both fresh-water and salt-water environments. The fresh-water clouds emitted sounds with a modal structure that was significantly different from that produced by the salt-water clouds. Furthermore, the smaller bubbles present in the salt-water clouds have a fundamental effect on the amplification of turbulence noise, generating sound at significant levels for frequencies up to several hundred Hertz. 相似文献
993.
Coupling of optical parametric processes in an optical superlattice through quadratic nonlinearity was analyzed theoretically. Solving the coupled equations, we found that efficient quasi-phase-matched third-harmonic (TH) generation depends not only on the magnitude of the coupling coefficients but also on their ratio. Theoretically, all the fundamental energy can be transferred to the TH at a particular ratio. In other cases, there exists an optimum condition that corresponds to a maximum TH conversion efficiency. The result is of practical importance for the design of TH devices. 相似文献
994.
A new idea of using change in index of refraction to suppress gain variation in a saturated semiconductor optical amplifier (SOA) is presented. This kind of gain compensation has the advantage of high speed because it involves two phenomena that always accompany each other. This compensation can be achieved with a nonsymmetrical Mach-Zehnder interferometer structure. Calculated results show that with this structure the input and output power of the SOA can be extended to nearly 10 dB from the former small-signal limit when less than 1-dB gain variation is permitted. Numerical simulations with an advanced dynamic model of the SOA agree with the calculated results. 相似文献
995.
H.-K. Zhao Q. Chen 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,55(4):419-427
We have investigated the spectral density of shot noise for the
system of a quantum dot (QD) coupled to two single-wall carbon
nanotube terminals irradiated with a microwave field on the QD. The
terminal features are involved in the shot noise through modifying
the self-energy of QD. The contributions of carbon nanotube
terminals to the shot noise exhibit obvious behaviors. The novel
side peaks are associated with the photon absorption and emission
procedure accompanying the suppression of shot noise. The shot noise
in balanced absorption belongs to sub-Poissonian, and it is
symmetric with respect to the gate voltage. The differential shot
noise displays intimate relation with the nature of carbon nanotubes
and the applied microwave field. It exhibits asymmetric behavior
for the unbalanced absorption case versus gate voltage. The Fano
factor of the system exhibits the deviation of shot noise from the
Schottky formula, and the structures of terminals obviously
contribute to it. The super-Poissonian and sub-Poissonian shot noise
can be achieved in the unbalanced absorption in different regime of
source-drain bias. 相似文献
996.
C.V. Subba Reddy Z.R. Deng Q.Y. Zhu Y. Dai J. Zhou W. Chen S.-I. Mho 《Applied Physics A: Materials Science & Processing》2007,89(4):995-999
Molybdenum trioxide (MoO3) and PPyxMoO3 (x=0.5 and 1) nanobelts were obtained by the simple hydrothermal process from MoO3 sol. The morphology and structure of the samples were characterized using X-ray diffractometry (XRD), Fourier transformation
infrared spectroscopy (FTIR), Raman spectra, SEM and AFM. The results show that the H atoms in polypyrrole are H-bonded with
the O atoms in the Mo=O bonds of MoO3 nanobelts. Using the electrolyte, we fabricated electrochemical cells with a configuration of Li/(LiPF6+EC+DMC)/(MoO3+acetyleneblack+PTFE) and studied discharge profiles.
PACS 81.07.BC; 81.05.Je; 82.47.Aa; 82.45.Fk; 82.45.Gj 相似文献
997.
When a particle is bounded in a central force field, the only nonvanishing component of the mean value for current density
is along the azimuthal direction; and the total current can therefore be defined. It is found that the total current is in
fact a mean value of a newly defined total current operator in the quantum mechanical state. Not only the total current operator
itself but also the mean total current has exact classical correspondence. 相似文献
998.
Ross A. Hatton Nicholas P. Blanchard Anthony J. Miller S.R.P. Silva 《Physica E: Low-dimensional Systems and Nanostructures》2007,37(1-2):124
A water-soluble composite of oxidised multi-wall carbon nanotubes and sulphonic acid sodium salt derivatised copper phthalocyanine for application in bi-layer organic solar cells is reported. Measurements of the topography of thin films of this novel material and of the valence electronic structure of its two components are used to rationalise the photovoltaic characteristics of a model organic heterojunction utilising the nanocomposite as the hole-extracting electrode and donor layer. 相似文献
999.
Ce3+-doped silica was synthesized by sol-gel technique. The absorption band at 252 nm of Ce3+-doped silica is close to the main absorption band of Ce(NO3)3 solution. Three different luminescence bands were observed in the samples annealed at temperatures from 100 to 1200 °C, and the intensity of these luminescence bands changed with the alteration of the heat-treating temperatures. In addition to two well-known main luminescence bands of 4f-5d transition of Ce3+ with the wavelength at 357 and 450 nm, a rarely reported luminescent band with the wavelength at 344 nm was also observed, which was attributed to some kind of oxygen-related defects of silica. 相似文献
1000.
We have made superconducting samples of the Y?Ba?Cu?O system with Fe substituted for the Cu. The percentage of Fe substituted varied from 2 to 100. The samples have been verified by x-ray diffraction to be single-phase 1–2–3 compounds. The 6% Fe substitution reduces Tc from 94 K to 80 K. The room temperature Mössbauer spectrum shows two pairs of doublets, indicating there are two distinct Cu sites in the sample. The most surprising result is that magnetic ordering of the Fe coexists with superconductivity of the material at 4.2 K. 相似文献