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1.
The influence of the sample orientation on the effective value of the hydrostatic piezoelectric coefficients d
h
(i)
of Sn2P2S6 crystals has been studied. The hydrostatic piezoelectric coefficients d
h
(1)
and d′
h
(3)
, were measured, d
h
(1)
=(244±3) pC/N and d′
h
(3)
=(92±1) pC/N. The hydrostatic piezoelectric coefficient d
h
(3)
for orthogonal axis system was calculated to be d
h
(3)
=(87±2) pC/N. The, optimal orientation of the sample has been found as (Xy l)−20°-cut. Maximal value of the effective hydrostatic piezoelectric coefficient d
h
(1)
equals 260 pC/N. Double rotated samples were also studied. The orientation of the samples insensitive to the pressure has
been found. The theoretical mean value of hydrostatic piezoelectric coefficient (d
h
)
mean
corresponding to randomly oriented Sn2P2S6 grains in a poled composite has been calculated to be (d
h
)
mean
=136 pC/N. 相似文献
2.
This contribution discusses the phenomena of retrograde condensation of one or two liquids. It w1 be shown that both phenomena can be well understood. Also the relation of retrograde condensation of one liquid phase with the condensation behavior of natural gas will be discussed. Similarly that of two liquid phases with multiple phase behavior occurring in low temperature reservoir fluids will be pointed out. 相似文献
3.
4.
Solichová D Melichar B Klejna M Jurašková B Královská L Bláha V Zd'ánský P Zadák Z 《Talanta》2003,60(2-3):459-465
Twelve self-sustaining nonagenarians, 10 women and two men, aged 94+/-3 years, and eight institutionalised nonagenarians, eight women, aged 91+/-1 year as well as 11 control subjects, seven women and four men, aged 84+/-5 years entered the study. Urinary neopterin, an indicator of systemic immune activation, and serum thiobarbituric acid reactive substances (TBARS), a marker of lipoperoxidation, were determined initially, and collection of the blood and urine samples was repeated at 3-month interval. Neopterin was measured in the urine specimens by reversed-phase high performance liquid chromatography. A C(18) reversed-phase column 3.3x150 mm, 5 mum-diameter packing Separon SGX was used. Potassium phosphate buffer (15 mmol l(-1), pH 6.4) at flow rate of 0.8 ml min(-1) was used as mobile phase. After centrifugation (5 min, 1300xg) and diluting 100 mul of urine specimens with 1.0 ml of mobile phase containing 2 g of disodium-EDTA per litre, a 20 mul sample was injected on a column. Neopterin was identified by its native fluorescence (353 nm excitation, 438 nm emission). Creatinine was determined by Jaffé kinetic reaction after dilution of sample 1:50 (v/v). The concentration of neopterin in urine was expressed as neopterin/creatinine ratio (mumol mol(-1) creatinine). TBARS were determined spectrofluorometrically using LS-5 spectrofluorimeter (excitation wavelength 528 nm, emission wavelength 558 nm) after extraction with n-butanol treatment with thiobarbituric acid. The significance of differences between nonagenarians and control group was examined by ANOVA-Kruskal-Wallis tests, using statistical software NCSS 6.0.21 (Kaysville, UT, 1996). The decision on significance was based on P=0.05. Urinary neopterin was significantly higher in institutionalised compared to self-sustaining subjects and controls (625+/-565 vs. 203+/-63 mumol mol(-1) creatinine, and 198+/-128 mumol mol(-1) creatinine, respectively, P=0.006). The serum TBARS were higher in both groups of nonagenarians (3.23+/-1.16 mumol l(-1) and 2.69+/-0.39 vs. 2.12+/-0.83 mumol l(-1) for the self-sustaining, institutionalised and controls, respectively, P=0.023). We conclude that the fluorimetric determinations of urinary neopterin and serum TBARS can be useful for the monitoring health status in the elderly patients. 相似文献
5.
Characteristic features and the temperature dependence of the small-polaron absorption spectrum are discussed using a recently published model. The physical interpretation of formal results is introduced, in particular a connection of small-polaron states with oscillator coherent states is emphasized. The continuous change of absorption curves with temperature is illustrated by numerical calculations. 相似文献
6.
Abachi S Akerlof C Baringer P Blockus D Brabson B Brom J Bylsma BG Chapman J Cork B DeBonte R Derrick M Errede D Gan KK Jung C Ken MT Koltick D Kooijman P Loeffler FJ Loos JS Low EH McIlwain RL Meyer DI Miller DH Musgrave B Neal H Ng CR Nitz D Ogren H Paik HW Price LE Rangan LK Repond J Rust DR Shibata EI Sugano K Thun R Tschirhart R 《Physical review letters》1987,59(22):2519-2522
7.
Abachi S Baringer P Bylsma BG DeBonte R Koltick D Loeffler FJ Low EH McIlwain RL Miller DH Ng CR Rangan LK Shibata EI Derrick M Gan KK Kooijman P Loos JS Musgrave B Price LE Repond J Sugano K Weiss JM Wood DE Blockus D Brabson B Brom J Jung C Ogren H Rust DR Akerlof C Chapman J Errede D Kesten P Meyer DI Nitz D Seidl AA Thun R Willutzky M Cork B 《Physical review letters》1986,57(16):1990-1993
8.
Detlef Schrder Jessica Loos Helmut Schwarz Roland Thissen Jana Roithova Zdenek Herman 《International journal of mass spectrometry》2003,230(2-3):113
Singly and doubly charged C4H3+/2+ ions generated upon electron ionization (EI) of the neutral precursors 1,3-butadiene, benzene, and exo-methylene cyclopropane, respectively, are examined by sector-field mass-spectrometry. Charge stripping of the mass-selected monocations affords the corresponding dications and charge exchange of the C4H32+ dications allows for the reverse redox process. Refined analysis and additional MS/MS studies suggest that the monocations are mixtures of isomeric ions formed upon ionization, whereas only a single type of dication seems to be formed. As an average of energy-resolved measurements, a vertical ionization energy of IEv(C4H3+)=16.5±0.4 eV is derived. In addition to the experimental work, density functional theory is used for a computational exploration of the mono- and dicationic species. The best theoretical estimates are IEa(C4H3+)=16.33 eV and IEv(C4H3+)=16.49 eV for the most stable isomer H2C=C---CCH+. Combination of the experimental and theoretical findings leads to the conclusion that the diacetylene cation C4H2+ has indeed a positive proton affinity of PA(C4H2+)=1.50±0.42 eV. 相似文献
9.
The40Ar/39Ar technique is an analytical variation of the K–Ar dating method. A known fraction of the39K in a sample is converted to39Ar by irradiation with fast neutrons. In an incremental heating experiment, the argon is released from the sample fractionally by stepwise heating. The result is a series of apparent ages.40Ar/39Ar age spectrum was determined for the sample Oase Vestfold. The minimum of the saddle-shaped age spectrum gives 1.0 billion years. 相似文献
10.
Laser flash photolysis and stopped-flow methods have been employed to determine the kinetics of the reactions of benzhydrylium ions with both termini of the thiocyanate ion. In contrast to previous investigations which reported sulfur/nitrogen ratios of k(S)/k(N) = 2-10 for the reactions of carbocations with SCN(-), values of k(S)/k(N) = 10(3)-10(4) are now derived from absolute rate constants. This discrepancy is explained by the fact that the data determined in this investigation are the first which refer to activation-controlled attack of carbocations at both termini of the thiocyanate ion, while previous reactivity ratios included diffusion-controlled reactions. It is concluded that the selectivities of the reactions of carbocations with the thiocyanate ion cannot be explained by the hard soft acid base principle. 相似文献