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1.
H. A. Azab A. M. El-Nady S. A. El-Shatoury 《Monatshefte für Chemie / Chemical Monthly》1994,125(10):1049-1057
Summary The acidity constants of adenosine-5-mono- and diphosphate (AMP andADP) were determined at 25.00±0.1°C by potentiometric titration in pure water and different solvent mixtures (methanol, ethanol, N,N-dimethylformamide, dimethylsulfoxide, acetone, and dioxane). The ionization ofAMP andADP depends on both the proportion and the nature of the organic solvent used. ThepK
a1 values for bothAMP andADP are slightly influenced as the solvent is enriched in ethanol and methanol and remains practically constant in presence of different amounts ofDMF andDMSO. A pronounced change in thepK
a1 values is observed as the solvent is enriched in acetone or dioxane. It is concluded that the electrostatic effect has only a relatively small influence on the dissociation equilibrium, whereas other solvent effects such as solvent basicity, hydrogen bonding and protonsolvent interactions play an important role.
Aciditätskonstanten von Adenosin-5-mono- und -diphosphat in verschiedenen organisch-wäßrigen Lösungsmittelgemischen
Zusammenfassung Die Aciditätskonstanten von Adenosin-5-mono- und -diphosphat wurden bei 25.0±0.1°C in reinem Wasser und in verschiedenen Lösungsmittelgemischen (Methanol, Ethanol, N,N-Dimethylformamid, Dimethylsulfoxid, Aceton und Dioxan) potentiometrisch bestimmt. Der Ionisierungsgrad vonAMP undADP hängt sowohl von der Menge als auch von der Art des organischen Lösungsmittels ab. DiepK a1-Werte vonAMP undADP werden durch Zugabe von Methanol und Ethanol nur wenig, durch verschiedene Mengen vonDMF undDMSO gar nicht, durch Aceton und Dioxan jedoch deutlich beeinflußt. Offensichtlich haben elektrostatische Effekte nur geringe Auswirkungen auf das Dissoziationsgleichgewicht, wogegen andere Faktoren wie Basizität des Lösungsmittels, Wasserstoffbrückenbindungen und Lösungsmittel-Proton-Wechselwirkungen eine bedeutende Rolle spielen.相似文献
2.
Pure and thiourea substituted single crystals of ammonium di-hydrogen phosphate have been grown from aqueous solution by isothermal solvent evaporation technique. Doped crystal exhibits prominent changes in physical and chemical properties. Single crystal XRD analyses of the samples are carried out and the results are compared. FTIR and UV–vis–NIR spectral analyses have been employed to identify the presence of various functional groups and the UV cut-off range in the grown crystals. Density measurements have been made and Photoconductivity studies revealed the negative photo conducting nature. Hardness measurement shows that the mechanical strength of the doped crystal is high when compared to pure ammonium di-hydrogen phosphate. The dielectric response of the samples has been studied in the frequency range 100 Hz–5 MHz at room temperature and the results are discussed. 相似文献
3.
Ákos Császár 《Journal of Mathematical Analysis and Applications》2004,297(2):490-494
The paper presents a formula for the γ-interior of a set under special conditions for , more general than those in the previous paper [Acta Math. Hungar. 80 (1998) 89-93]. There are also some applications. 相似文献
4.
The paper concerns applications of LR-115A, CR-39 and PM-355 solid-state nuclear-track detectors (SSNTDs) for investigation of pulsed fluxes of protons below 300 keV. The proton streams were generated by the RPI-IBIS device operated with hydrogen puffing [Baranowski et al. 2000. Studies of hydrogen discharges in RPI-type devices with different electrode configurations. Czech. J. Phys. 50 (Suppl. S3), 101–107]. To perform ion mass- and energy-analysis, a Thomson mass-spectrometer equipped with a special input system and exchangeable detectors was used. A quantitative analysis of proton tracks upon Thomson parabolas was performed by means of an optical microscope equipped with a CCD camera. It made possible to measure proton tracks and to determine their statistics. The paper presents proton energy spectra recorded with the selected detectors, and responses of these detectors to protons of energy from about 30 to 300 keV. The results are important for verification of detector characteristics and for measurements of protons at different experimental conditions. 相似文献
5.
A. Szydowski B. Sartowska A. Banaszak J. Choiski I. Fija M. Jaska A. Korman M.J. Sadowski 《Radiation measurements》2005,40(2-6):401-403
The calibration diagrams, i.e. track diameters and track depths versus ion energy and etching time, as obtained for PM-355 track detector irradiated with He-ions are presented. The both detector characteristics are compared. The track etch rate is determined by two methods, as a function of the etch pit depth and the ion energy loss. 相似文献
6.
Ying Zhang Yong-Guang Gao You-Di Shi Lian-Qian Tan Jessica S. Yue Zhong-Lin Lu 《中国化学快报》2015,26(7):894-898
A novel [12]aneN3-based BODIPY sensor 1 can be applied in the sequential recognition of Cu2 and ADP in aqueous solution and living cells with high selectivity and sensitivity 相似文献
7.
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9.
Samples from sheets of the polymeric material PM-355 have been exposed to X-rays from a 50 kV X-ray tube in the dose range of 10–300 kGy. The resultant effect of X-ray irradiation on the structural properties of PM-355 has been investigated using different techniques such as X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Vickers hardness and refractive index measurements. The results indicate that the X-ray irradiation of PM-355 in the dose range of 10–20 kGy causes initially chain scission. Above 20 and up to 100 kGy, the active free radicals produced from scission contribute to chemical reactions that lead to the crosslinking. Thus, the X-ray irradiation in the dose range of 20–100 kGy leads to a more compact structure of the PM-355 polymer, resulting in an enhancement of its Vickers hardness and refractive index. Moreover, the irradiation in the dose range of 100–300 kGy leads to the predominance of the degradation. This degradation is reported by FTIR spectroscopy and enhances the degree of ordering in the degraded samples as revealed by XRD technique. Additionally, it decreases both the Vickers hardness and refractive index of the PM-355 samples. 相似文献
10.
《Quaestiones Mathematicae》2013,36(1):17-50
Abstract Boundary value problems and variational inequalities, associated with second order elliptic operators, will be studied in a Hilbert space framework. In this space, functions will have (at least) locally square integrable derivatives of order up to two. Also the conormal derivative, extended by continuity, will be square integrable on the boundary of the region considered. Criteria for approximating elements of the Hilbert space by smooth functions will be given and thus closed convex sets, associated with inequalities on the boundary, exist. The idea of the present approach originated from the method suggested by Lions and Magenes, for putting some regular elliptic problems in the variational setting. The differential equation is multiplied by Qv, with Q some operator and v a function and the result is integrated as required. 相似文献