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A. Visvanathan E. G. Funk J. W. Mihelich 《Zeitschrift für Physik A Hadrons and Nuclei》1974,271(4):339-343
TheK-internal conversion coefficients have been measured by the XPG technique for a number of low energyγ-ray transitions whose energies do not exceed theK-binding energies by more than 4 keV. Using Si(Li) detectors in singles and coincidence arrangements, the following results were obtained: 63.1 keV El in169Tm(αK=1.02±0.15), 72.0 keV E1 in187Re (0.75±0.05), 57.8 keV M1 in162Ho (11.42±0.67), 56.6 keV M1 in164Ho (12.04±0.70), and 67.1 keV M1 in174Lu(10.25±0.58). The experimental results are compared with the theoretical calculations which include transition energies down to 1 keV above threshold. 相似文献
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D. P. Singh R. Visvanathan A. E. Duncan B. Duponchel Y. Boussoualem S. Kumar 《Liquid crystals》2019,46(3):376-385
CdSe quantum dots (QDs) dispersed ferroelectric liquid crystal (FLC) has been subjected to small and wide-angle X-ray scattering and atomic force microscopy to understand the molecular organization in chiral smectic C (SmC*) phase. SAXS indicates that the presence of QDs causes enhancement in the smectic layer separation. The smectic order parameter for neat FLC and FLC–QDs mixtures is obtained in the range of 0.6 to 0.85. Both smectic order parameter and structural tilt are found to be lesser for FLC–QDs mixtures as compared to neat FLC. The insertion of QDs in SmC* matrix causes localized smectic layer distortion in such a way that spontaneous polarization remains almost the same but the electro-optic switching of molecules becomes faster. We have outlined the superiority of FLC–QDs mixtures for electrical energy storage and their suitability in electronic devices. 相似文献
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Ni M Reichenbach SE Visvanathan A TerMaat J Ledford EB 《Journal of chromatography. A》2005,1086(1-2):165-170
Identifying compounds of interest for peaks in data generated by comprehensive two-dimensional gas chromatography (GC x GC) is a critical analytical task. Manually identifying compounds is tedious and time-consuming. An alternative is to use pattern matching. Pattern matching identifies compounds by matching previously observed patterns with known peaks to newly observed patterns with unidentified peaks. The fundamental difficulty of pattern matching comes from peak pattern distortions that are caused by differences in data acquisition conditions. This paper investigates peak pattern variations related to varying oven temperature ramp rate and inlet gas pressure and evaluates two types of affine transformations for matching peak patterns. The experimental results suggest that, over the experimental ranges, the changes in temperature ramp rate generate non-linear pattern variations and changes in gas pressure generate nearly linear pattern variations. The results indicate the affine transformations can largely remove the pattern variations and can be used for applications such as pattern matching and normalizing retention times to retention indices. 相似文献
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The kinetics of the reaction of diols with various hydrogen halides is discussed. The reaction involves neighbouring group participation as postulated earlier, the rate of substitution being faster for a heavier nucleophile. The reactions are inert in aqueous systems as the X? nucleophilicity becomes negligible as compared to the nucleophilicity of water. At and above 7·5 per cent. water these reactions do not occur. Variation of dielectric constant also notably affects the process. 相似文献
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Thiol‐acrylate main‐chain liquid‐crystalline elastomers with tunable thermomechanical properties and actuation strain 下载免费PDF全文
Mohand O. Saed Amir H. Torbati Chelsea A. Starr Rayshan Visvanathan Noel A. Clark Christopher M. Yakacki 《Journal of Polymer Science.Polymer Physics》2017,55(2):157-168
The purpose of this study was to investigate the influence of cross‐linking on the thermomechanical behavior of liquid‐crystalline elastomers (LCEs). Main‐chain LCE networks were synthesized via a thiol‐acrylate Michael addition reaction. The robust nature of this reaction allowed for tailoring of the behavior of the LCEs by varying the concentration and functionality of the cross‐linker. The isotropic rubbery modulus, glass transition temperature, and strain‐to‐failure showed strong dependence on cross‐linker concentration and ranged from 0.9 MPa, 3 °C, and 105% to 3.2 MPa, 25 °C, and 853%, respectively. The isotropic transition temperature (Ti) was shown to be influenced by the functionality of the cross‐linker, ranging from 70 °C to 80 °C for tri‐ and tetra‐functional cross‐linkers. The magnitude of actuation can be tailored by controlling the amount of cross‐linker and applied stress. Actuation increased with increased applied stress and decreased with greater amounts of cross‐linking. The maximum strain actuation achieved was 296% under 100 kPa of bias stress, which resulted in work capacity of 296 kJ/m3 for the lowest cross‐linked networks. Overall, the experimental results provide a fundamental insight linking thermomechanical properties and actuation to a homogenous polydomain nematic LCE networks with order parameters of 0.80 when stretched. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 157–168 相似文献
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Hollingsworth BV Reichenbach SE Tao Q Visvanathan A 《Journal of chromatography. A》2006,1105(1-2):51-58
This paper investigates methods for comparing datasets produced by comprehensive two-dimensional gas chromatography (GC x GC). Chemical comparisons are useful for process monitoring, sample classification or identification, correlative determinations, and other important tasks. GC x GC is a powerful new technology for chemical analysis, but methods for comparative visualization must address challenges posed by GC x GC data: inconsistency and complexity. The approach extends conventional techniques for image comparison by utilizing specific characteristics of GC x GC data and developing new methods for comparative visualization and analysis. The paper describes techniques that register (or align) GC x GC datasets to remove retention-time variations; normalize intensities to remove sample amount variations; compute differences in local regions to remove slight misregistrations and differences in peak shapes; employ color (hue), intensity, and saturation to simultaneously visualize differences and values; and use tools for masking, three-dimensional visualization, and tabular presentation with controls for graphical highlights to significantly improve comparative analysis of GC x GC datasets. Experimental results indicate that the comparative methods preserve chemical information and support qualitative and quantitative analyses. 相似文献
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Levels in 162, 164, 166Er have been studied using the (α, 2nγ) reaction at an energy of 24 MeV. Singles spectra, γ-γ coincidence spectra, and angular distributions were obtained using Ge(Li) detectors. Transitions from levels in the γ-vibrational bands up to the 8+' in 162, 164Er and 10+' in 166Er were observed and M1/E2 mixtures were determined for many of these transitions. There is a relative shifting upward of the even-spin levels in the γ-band of 166Er while the analogous levels of 162, 164Er are shifted downward with the effect being most pronounced for162Er. The standard phenomenological band-mixing parameters z2 and z02 were obtained from γ-ray branching ratio data and the values are probably correlated with the staggering of levels in the γ-bands. The ratios of the intraband and interband E2 transition strengths which are related to the intrinsic quadrupole moments of the ground-state and γ-bands are discussed. A number of other levels are observed in 162, 164Er and some of these correspond to negative parity states reported in decay studies. 相似文献
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Jong Seung Kim Richard A. Bartsch Visvanathan Ramesh 《Journal of inclusion phenomena and macrocyclic chemistry》2000,36(3):287-299
Asymmetrical cis-5,6-dimethyl-6-oxyacetoxy-(2,3)(9,10)-dibenzo-16-crown-5 was synthesized by a multi-step sequence and its stereochemistry determined by NOE experiments. Introduction of the 6-methyl group markedly reduces the stability constant for complexation of Na+ and K+ by the ionized form of the lariat ether carboxylic acid. 相似文献