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101.
Neetu Ahlawat Ashish Agarwal Sujata Sanghi Nawal Kishore 《Solid State Ionics》2009,180(26-27):1356-1361
Glasses having compositions xLi2O∙(85 − x)Bi2O3∙15SiO2 (x = 35, 40, and 45 mol%) were prepared by normal melt quenching technique. Electrical relaxation and conductivity in these glasses were studied using impedance spectroscopy in the frequency range from 20 Hz to 1 MHz and in the temperature range from 453 to 603 K. The ac and dc conductivities, activation energy of the dc conductivity and relaxation frequency were extracted from the impedance spectra. The dc conductivity increases with increase in Li2O content providing modified glass structure and large number of mobile lithium ions. Similar values of activation energy for dc conduction and for conductivity relaxation time indicate that the ions overcome the same energy barrier while conducting and relaxing. The non-exponential character of relaxation processes increases with decrease in stretched exponential parameter ‘β’ as the composition parameter ‘x’ increases. The observed conductivity spectra follow a power law with exponent ‘s’ which increases regularly with frequency and approaches unity at higher frequencies. Nearly constant losses (NCL) characterize this linearly dependent region of the conductivity spectra. A deviation from the ‘master curve’ for various isotherms of conductivity spectra was also observed in the high-frequency region and at low temperatures, which supports the existence of different dynamic processes like NCL in addition to the ion hopping processes in the investigated glass system. 相似文献
102.
A. Dwivedi S. A. Siddiqui O. Prasad L. Sinhal N. Misra 《Journal of Applied Spectroscopy》2009,76(5):623-629
The molecular geometry and vibrational frequencies of 5-phenyl-2-(4-pyridyl)pyrimidine in the ground state have been calculated
by the density functional theory with B3LYP/6-311G(d) as the basis set. The observed frequencies of 5-phenyl-2-(4-pyridyl)pyrimidine
and those calculated are nearly the same. The form of the modes for all fundamentals is based on potential energy distribution
calculations. 相似文献
103.
Energy transfer has been studied from Er3+ to Eu3+ ions on excitation with NIR photons (796 and 980 nm) with and without Yb3+ ions. It is found that in one case the presence of Yb3+ enhances the fluorescence yield (980 nm excitation) whereas in the other case it quenches (796 nm excitation). Energy transfer from Er3+ ion's levels 4S3/2 and 2H11/2 is verified by decay curve analysis in both the cases. The nature of interaction between the donor (Er) and the acceptor (Eu) ions is found to be dipole-dipole. The energy transfer parameters viz. transfer probability, critical distance etc. have been calculated. 相似文献
104.
105.
A simple spectrophotometric method applicable to waste water bodies is developed for the determination of anionic surfactant (AS). An ion‐association complex is formed between an anionic surfactant Sodium dodecyl sulphate (SDS) and a cationic dye Crystal Violet (CV). The dark blue colored complex can be easily extracted in organic solvent benzene. The absorbance of the complex in benzene layer is measured spectrophotometrically at maximum wave length (λ max) of 565 nm. Under the optimal experimental conditions, absorbance of the organic extractant obeyed Beer's law over the range of 0.75–10.00 μg mL?1 of SDS and the LOD was 0.01312 μg L?1. It is noticed that the present method is much easier, less time consuming and applicable to accelerated urbanization and industrial development found in newly formed Chhattisgarh state in Central India. The validity of the method was tested in regionalized industrial and domestic waste water runoff. 相似文献
106.
Z Irani Y K Dwivedi M D Williams 《The Journal of the Operational Research Society》2009,60(10):1322-1334
Broadband offers several benefits to consumers over its preceding technology ‘narrowband’. Despite it offering such benefits, many countries are still experiencing low levels of adoption of broadband technology by consumers. This study presents an extended technology acceptance model (TAM) that integrates perceived resources, self-efficacy and social influence into the TAM in order to investigate factors determining consumer adoption of broadband. The model was empirically tested employing data collected from a survey of broadband consumers in the United Kingdom. A regression analysis was conducted to evaluate the influence of predictive constructs on behavioural intention to adopt broadband and actual adoption behaviour. Findings of the study indicated that all variables significantly affected consumers' behavioural intention to adopt broadband. The outcomes of the paper will be useful for the stakeholders such as internet service providers and governments interested in encouraging the adoption of broadband. The implications of this work to both researchers and practitioners is discussed. 相似文献
107.
Mardilovich A Craig JA McCammon MQ Garg A Kokkoli E 《Langmuir : the ACS journal of surfaces and colloids》2006,22(7):3259-3264
The interaction of the alpha5beta1 integrin with its ligand, fibronectin, supports numerous adhesive functions and has an important role in health and disease. In recent years, there has been a considerable effort in designing fibronectin-mimetic peptides to target the integrin. However, to date, the therapeutic use of these peptides has been limited, as they cannot accurately mimic fibronectin's binding affinity for alpha5beta1. A peptide-amphiphile (PR_b) was synthesized with a peptide headgroup composed of four building blocks: a spacer; RGDSP, the primary recognition site for alpha5beta1; PHSRN, the synergy binding site; and a linker. The linker was designed to mimic two important criteria: the distance and the hydrophobicity/hydrophilicity between PHSRN and RGD in fibronectin. Human umbilical vein endothelial cells were seeded on different substrates and evaluated in terms of adhesion, spreading, specificity, cytoskeleton organization, focal adhesions, and secretion of extracellular fibronectin. This peptide was shown to perform comparably to fibronectin, indicating that a biomimetic approach can result in the design of novel peptides with therapeutic potential for biomaterial functionalization. 相似文献
108.
109.
Colorimetric detection of anions (HSO4? and CN?) was achieved via analyte triggered colour changing of the dipodal and tripodal sensors in CH3CN–H2O (1:1). The sensors exhibited very sharp visual colour changes and fluorescence quenching–enhancing effect upon addition of the HSO4? and CN?. The large downfield shift of the NH proton signals in 1H-NMR complexation studies and quantum chemical DFT calculations proved the formation of hydrogen-bonded complexes where no proton transfer mechanism was found. 相似文献
110.
Maheshkumar Prakash Patil Ashish Anirudh Rokade Daniel Ngabire Gun-Do Kim 《Journal of Cluster Science》2016,27(5):1737-1750
The green synthesis of silver nanoparticles (AgNPs) has been proposed as a simple, eco-friendly and cost effective alternative to chemical and physical methods. The Rhus chinensis plant is one of the well studied medicinal plant and its galls find excellent clinical and therapeutic applications. The present study reports the use of water extract from galls of R. chinensis as a reducing agent and formation of AgNPs from silver nitrate solution by a green synthesis route. The AgNPs formation was observed visually by color change and the absorbance peak at 450 nm was observed by UV–Visible spectrophotometer. The shape, size, and morphology of synthesized AgNPs were monitored by transmission electron microscopy and field-emission scanning electron microscopy. The face centered cubic structure of AgNPs was confirmed by X-ray diffraction pattern and element composition by energy dispersive X-ray analysis. The Fourier transform infrared spectroscopy spectrum revealed that the presence of components acts as a reducing and capping agent. The antibacterial activity was performed using the agar well diffusion method. Minimum inhibitory concentration and minimum bactericidal concentration were determined by broth dilution and spread plate method respectively. Synthesized nanoparticles were spotted as triangular and hexagonal shape and the particle size was around 150 nm. 相似文献