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21.
In this paper, we study pseudo-Riemannian submanifolds of a pseudo-hyperbolic space \(\mathbb H^{m-1}_s (-1) \subset \mathbb E^m_{s+1}\) with 2-type pseudo-hyperbolic Gauss map. We give a characterization of proper pseudo-Riemannian hypersurfaces in \(\mathbb H^{n+1}_s (-1) \subset \mathbb E^{n+2}_{s+1}\) with non-zero constant mean curvature and 2-type pseudo-hyperbolic Gauss map. For \(n=2\), we prove classification theorems. In addition, we show that the hyperbolic Veronese surface is the only maximal surface fully lying in \(\mathbb H^4_2 (-1) \subset \mathbb H^{m-1}_2 (-1)\) with 2-type pseudo-hyperbolic Gauss map. Moreover, we prove that a flat totally umbilical pseudo-Riemannian hypersurface \(M^n_t\) of the pseudo-hyperbolic space \(\mathbb {H}^{n+1}_t(-1) \subset \mathbb E^{n+2}_{t+1}\) has biharmonic pseudo-hyperbolic Gauss map. 相似文献
22.
T. Korkut H. Korkut A. Karabulut G. Budak 《Journal of Radioanalytical and Nuclear Chemistry》2011,287(2):501-504
Elemental concentrations of five different seed coats of fruit seeds were determined by using wavelength-dispersive X-ray
fluorescence (WDXRF) technique. Basic aim of this study is to measure mass percentages of macro, micro and trace elements
in samples. Besides, analyze results have been commented in terms of correlation between the same element types in seed coats
of different fruits. Some interesting results have been obtained about element quality and quantity. 相似文献
23.
Siddekha A Nizam A Pasha MA 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,81(1):431-440
We describe a one-pot four component synthesis of pyranopyroles from aryl aldehydes, ethyl acetoacetate, malononitrile and hydrazine hydrate in the presence of catalytic amounts of an organocatalyst imidazole in water as medium. A plausible mechanism for the formation of imidazole catalyzed pyranopyrazoles has been envisaged. This method is rapid, simple, provides products in good yield, and is eco-friendly. In addition, based on the optimized geometry, the frequency and intensity of the vibrational bands of 6-amino-4-(4'-methoxyphenyl)-5-cyano-3-methyl-1-phenyl-1,4-dihydropyrano[2,3-c]pyrazole were obtained by the density functional theory (DFT) calculations using 6-31G(d,p) basis set. The vibrational frequencies were calculated and the scaled values have been compared with experimental FT-IR and FT-Raman spectra. The observed and the calculated frequencies are found to be in good agreement. 相似文献
24.
Ukrainian Mathematical Journal - We first classify space-like surfaces in the Minkowski space , de Sitter space , and hyperbolic space ?3 with harmonic Gauss maps. Then we characterize and... 相似文献
25.
A flow injection catechol biosensor based on tyrosinase entrapped in carbon nanotube modified polypyrrole biocomposite film on a glassy carbon surface has been developed. Amperometric response was measured as a function of concentration of catechol, at a fixed bias voltage of −50 mV at a flow rate of 1 mL/min. The proposed biosensor exhibited impressive analytical performance such as a linear range between 3 and 50 μM, a short response time (10 s), a detection limit of 0.671 μM and an excellent operational (with a relative standard deviation of 0.54%) and long-term stability (85% remained after 10th week). A comparison of the analytical parameters of the developed biosensor with polypyrrole/tyrosinase film electrode was performed in the study. CNT was shown to enhance the electron transfer between the electrode and enzyme and capable to carry higher bioactivity owing to its intensified surface area. 相似文献
26.
Dağlı Özge Köse Dursun Ali İçten Okan Avcı Gülçin Alp Şahin Onur 《Journal of Thermal Analysis and Calorimetry》2019,136(4):1467-1480
Journal of Thermal Analysis and Calorimetry - The coumarilate (coum?) and 1,10-phenanthroline (phen) mixed ligand complexes of Co(II) (1), Ni(II) (2) Cu(II) (3) and Zn(II) (4) were... 相似文献
27.
28.
The effect of sodium carboxymethyl cellulose (Na-CMC) on the corrosion behavior of mild steel in 1.0 mol·L−1 HCl solution has been investigated by using weight loss (WL) measurement, potentiodynamic polarization, linear polarization resistance (LPR), and electrochemical impedance spectroscopy (EIS) methods. These results showed that the inhibition efficiency of Na-CMC increased with increasing the inhibitor concentration. Potentiodynamic polarization studies revealed that the Na-CMC was a mixed type inhibitor in 1.0 mol·L−1 HCl. The adsorption of the inhibitor on mild steel surface has been found to obey the Langmuir isotherm. The effect of temperature on the corrosion behavior of mild steel in 1.0 mol·L−1 HCl with addition of 0.04% of Na-CMC has been studied in the temperature range of 298–328 K. The associated apparent activation energy (E*a) of corrosion reaction has been determined. Scanning electron microscopy (SEM) has been applied to investigate the surface morphology of mild steel in the absence and presence of the inhibitor molecules. 相似文献
29.
In this study, simultaneous determination of toxic hydrazine and nitrite was performed on composite electrodes of poly(Nile blue)(NB), carbon nanotube(CNT) and gold nanoparticles(AuNPs). The prepared AuNPs/CNT/poly(NB)/GCE was used for as a sensor platform for individual and simultaneous determination of hydrazine and nitrite. Electrodes were characterized by HRTEM, SEM, XPS, EIS. The LOD for nitrite and hydrazine was 5.0 μM and 3.1 μM at AuNP/CNT/poly(NB)/GCE, respectively. Also, sensitive amperometric determinations of hydrazine and nitrite were performed and LOD were calculated as 0.33 μM and 0.68 μM, respectively. The method was applied to sausage and river water samples and recovery results were obtained in the range 85–115 %. 相似文献
30.
Swelling studies of copolymeric acrylamide/crotonic acid hydrogels as carriers for agricultural uses
In this study, highly swollen acrylamide/crotonic acid hydrogels (in a rod form) containing some inorganic salts such as ammonium nitrate, potassium nitrate and ammonium sulphate used as fertilizer, an agricultural drug such as Dalapon (sodium 2,2‐dichloropropionate) and two crosslinkers such as ethylene glycol dimethacrylate and 1,4‐butandiol dimethacrylate were prepared by copolymerization of acrylamide and crotonic acid with γ‐radiation. As a result of swelling tests, the influence of γ‐ray dose and relative content of crotonic acid on the swelling properties, the diffusional behavior of water, diffusion coefficients and network properties of the hydrogel systems were examined. Acrylamide/crotonic acid hydrogels containing these salts and agricultural drug were swollen in the range 2045–400% in water, while polyacrylamide hydrogels swelled in the range 660–700%. Water intake of hydrogels followed a nonFickian‐type diffusion. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献