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1.
Sorption and diffusion of Sr were examined using a typical Japanese bentonite. The experimental results showed that Sr sorption on the bentonite had linear relationship between the equilibrium Sr concentration and Sr sorption amount, i.e., Henry’s type of sorption, in wide initial Sr concentration from 1.1 × 10?9 to 1.1 × 10?4 mol L?1 at pH 10. The Sr sorption also indicated pH dependence in pH range between 2 and 12. Sorption modelling calculation indicated that cation-exchange reactions contributed to Sr sorption in the pH range studied and a surface complexation reaction was predominant above pH 8. Diffusion of Sr in loosely compacted bentonite bed was described by pore and surface diffusion and surface complexation of Sr. Chemical-transport calculations reproduce the diffusion data at pH 5 using the cation-exchange parameters obtained in the analysis of the batch sorption experiment. 相似文献
2.
K. Mettler 《Applied Physics A: Materials Science & Processing》1977,12(1):75-82
Electronic surface parameters of GaAs have been determined from a qualitative and quantitative analysis of the relative photoluminescence
intensity at 300 K. Characteristics of etched (100) surfaces ofn- andp-type liquid phase epitaxial GaAs have been found to be governed by negative surface charges. A density of charged surface
states of about 1012 cm−2 and a band bending of 0.59 eV have been found forn-type material with an electron concentration of 1.1×1017 cm−3. Forp-type samples with hole densities ranging from 6×1015 to 4.3×1018 cm−3 the estimated density of negatively charged surface states was below 2×1011 cm−2, and the band bending was not more than a few kT. 相似文献
3.
A novel, simple, sensitive and selective spectrofluorimetric method was developed for the determination of trace amounts of
chlorzoxazone and Ibuprofen in pharmaceutical tablets using optical sensor Eu-Tetracycline HCl doped in sol–gel matrix. The
chlorzoxazone or Ibuprofen can remarkably enhance the luminescence intensity of Eu-Tetracycline HCl complex doped in a sol–gel
matrix in dimethylformamide (DMF) at pH 9.7 and 6.3, respectively, λex = 400 nm. The enhancing of luminescence intensity peak of Eu-Tetracycline HCl complex at 617 nm is proportional to the concentration
of chlorzoxazone or Ibuprofen a result that suggested profitable application as a simple optical sensor for chlorzoxazone
or Ibuprofen assessment. The dynamic ranges found for the determination of chlorzoxazone and Ibuprofen concentration are 5 × 10−9–1 × 10−4 and 1 × 10−8–7 × 10−5 mol L−1, and the limit of detection (LOD) and quantitation limit of detection (LOQ) are 3.1 × 10−10 , 9.6 × 10−10 and 5.6 × 10−10, 1.7 × 10−9 mol L−1, respectively. 相似文献
4.
H. Ryssel K. Müller K. Haberger R. Henkelmann F. Jahnel 《Applied Physics A: Materials Science & Processing》1980,22(1):35-38
The diffusion behaviour of implanted boron in silicon was investigated using the10B(n,α)7 Li nuclear reaction. An anomalous behavior with a strong reduction of the diffusivity above an effective solubility limit
at 1.5×1019, 6×1019, and 1.1×1020 cm−3 was found for annealing temperatures of 800, 900, and 1,000°C, respectively. 相似文献
5.
The processes of electrochemical decomposition of the solid electrolyte RbCu4Cl3I2 at the vitreous carbon electrode and chemical decomposition of RbCu4Cl3I2 by iodine has been investigated. The anodic decomposition of the electrolyte occurs in two steps. At first, the oxidizing
electrode reaction of Cu+ ions up to Cu2+ ions takes place at potentials higher than 0.57 V and onto the electrode surface the layer of decomposition products is formed,
including the compound of divalent copper RbCuCl3. Then the oxidizing reaction of I ions occurs at potentials higher than approximately 0.67 V with deposition of the iodine
layer onto the electrode surface. The deposition rate of the layers of decomposition products is controlled by instantaneous
nucleation and two-dimensional growth of the deposit. It was shown that slow diffusion of the iodine in the reaction product
layer is a limiting step in the chemical interaction of iodine with RbCu4Cl3I2. For the compressed RbCu4Cl3I2 sample investigated, iodine diffusion coefficient was calculated to be 6.2×10−7 cm2 s−1. Iodine loss from the glassy carbon surface is about 1.1×10−4 g cm−2 s−1 at the thickness of the RbCu4Cl3I2 sample is equal to 2 mm. 相似文献
6.
Ganesh Prasad Yogesh Prasad G. S. Gusain Manjari Badoni J. M. S. Rana R. C. Ramola 《Indian Journal of Physics》2009,83(6):887-892
Radon was measured in soil-gas and groundwater in the Budhakedar area of Tehri Garhwal, India in summer and winter to obtain
the seasonal variation and its correlation with radon exhalation rate. The environmental surface gamma dose rate was also
measured in the same area. The radon exhalation rate in the soil sample collected from different geological unit of Budhakedar
area was measured using plastic track detector (LR-115 type II) technique. The variation in the radon concentration in soil-gas
was found to vary from 1098 to 31,776 Bq.m−3 with an average of 7456 Bq.m−3 in summer season and 3501 to 42883 Bq.m−3 with an average of 17148 Bq.m−3 in winter season. In groundwater, it was found to vary from 8 to 3047 Bq.l−1 with an average value 510 Bq.l−1 in summer and 26 to 2311 Bq.l−1 with an average value 433 Bq.L−1 in winter. Surface gamma dose rate in the study area varied from 32.4 to 83.6 μR.h−1 with an overall mean of 58.7 μ-R.h−1 in summer and 34.6 to 79.3 μR.h−1 with an average value 58.2 μR.h−1 in winter. Radon exhalation rate from collected soil samples was found to vary from 0.1 × 10−5 to 5.7 × 10−5 Bq.kg−1.h−1 with an average of 1.5 × 10−5 Bq.kg−1.h−1 in summer season and 1.7 × 10−5 to 9.6 × 10−5 Bq.kg−1.h−1 with an average of 5.5 × 10−5 Bq.kg−1.h−1. A weak negative correlation was observed between radon exhalation rate from soil and radon concentration in the soil. Radon
exhalation rate from the soil was also not found to be correlated with the gamma dose rate, while it shows a positive correlation
with radon concentration in water in summer season. Inter-correlations among various parameters are discussed in detail.
相似文献
7.
Three sensitive and selective new alternatives for fluorometric determination of cerium(III) are described in this study.
Ce(III) is highly fluorescent in sodium pyrophosphate, sodium trimetaphosphate, and sodium tetrametaphosphate solutions. For
these reagents, the maximum excitation/emission wavelengths are 300/350, 297/340, and 299/352 nm, respectively. Maximum fluorescence
intensities are obtained by irradiating Ce(III) dissolved in 0.033 g L−1 sodium pyrophosphate, 41.4 g L−1 sodium trimetaphosphate, and 0.96 g L−1 sodium tetrametaphosphate at room temperature. The fluorescence intensities are linear over the range 0.001–30, 0.001–75,
and 0.001–70 μg ml−1. The detection limits are calculated as 9.5 × 10−3, 1.1/10−3, and 3.8 × 10-3 μg ml−1 Ce(III), respectively. The relative standard deviations for 15/0.05 Μg ml−1 Ce(III) are 1.1/1.2, 1/1.1, and 1.2/1.3%, respectively. Quenching effects of other lanthanides and some inorganic anions
were investigated. The methods have been applied to rare earth mixtures with a good accuracy. 相似文献
8.
A. M. Orlov I. O. Yavtushenko M. V. Churilov 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2010,4(5):831-835
The adsorption and kinetic processes of the formation of gas bubbles passivating the surface during polarization of copper
and graphite electrodes in 1% aqueous solution of sulfuric acid have been investigated. Three stages of the process related
to the recharging of the double electric layer—adsorption accumulation of the gas escaping from the surface, the critical
nucleation of the gas bubbles, and their subsequent growth—have been revealed, distinguished, and quantitatively estimated.
It has been shown that potential leveling at the steady-state value specified by the Tafel equation is unambiguously associated
with achievement of the limiting surface area screened by the gas bubbles for each particular current density. The surface
diffusion constants D
H = (1.5–4.4) × 10−4 and (0.1–3.8) × 10−5 cm2/s of hydrogen on copper and graphite, respectively, and D
O = (1.8–4.5) × 10−7 cm2/s of oxygen on graphite during the motion toward the drain (the gas bubbles) have been calculated. 相似文献
9.
Lee Ming-Kwei Yen Chih-Feng Chiu Shih-Chen 《Applied Physics A: Materials Science & Processing》2011,104(4):1175-1180
The electrical characteristics of thin TiO2 films prepared by metal–organic chemical vapor deposition grown on a p-type InP substrate were studied. For a TiO2 film of 4.7 nm on InP without and with ammonium sulfide treatment, the leakage currents are 8.8×10−2 and 1.1×10−4 A/cm2 at +2 V bias and 1.6×10−1 and 8.3×10−4 A/cm2 at −2 V bias. The lower leakage currents of TiO2 with ammonium sulfide treatment arise from the improvement of interface quality. The dielectric constant and effective oxide
charge number density are 33 and 2.5×1013 cm2, respectively. The lowest mid-gap interface state density is around 7.6×1011 cm−2 eV−1. The equivalent oxide thickness is 0.52 nm. The breakdown electric field increases with decreasing thickness in the range
of 2.5 to 7.6 nm and reaches 9.3 MV/cm at 2.5 nm. 相似文献
10.
S. F. Baranovskii P. A. Bolotin M. P. Evstigneev D. N. Chernyshev 《Journal of Applied Spectroscopy》2008,75(2):251-260
We have used spectrophotometry to study self-association and complexation with DNA by organic heterocyclic compounds in the
acridine and phenothiazine series: proflavin, thionine, and methylene blue. Based on the experimental concentration dependences
of the molar absorption coefficient of the molecules in an aqueous buffer solution (0.01 M NaCl, 0.01 M Na2EDTA, 0.01 M Tris, pH 7.4, T = 298 K), we have determined the equilibrium dimerization constants for the dyes and the DNA
complexation parameters using the Scatchard and McGhee-von Hippel models. The observed increase in the cooperativity parameters
as the dimerization constants of the ligands increase allowed us to hypothesize that the same interactions occur between dye
molecules adsorbed on DNA as in their self-association. The equilibrium DNA-binding constants for the ligands, obtained using
the McGhee-von Hippel cooperative model, are (20.9 ± 2.7)·103 M−1 for proflavin and (33.8 ± 4.1)·103 M−1 for thionine. Using the Scatchard model, taking into account intercalation and “external” binding of ligands with DNA, we
determined the DNA complexation constants for methylene blue: (26.4 ± 4.6)·103 and (96 ± 17)·103 M−1 respectively. Based on analysis of the data obtained, we hypothesized that the predominant type of binding with DNA is intercalation
binding in the case of proflavin and thionine, and “external” binding with the DNA surface in the case of methylene blue.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 2, pp. 242–249, March–April, 2008. 相似文献
11.
A. Axmann M. Schulz C. R. Fritzsche 《Applied Physics A: Materials Science & Processing》1977,12(2):173-178
The ions of Sb, As, and P have been implanted into germanium at energies ranging from 200 keV to 700 keV. Annealing was performed
at 400°C, 550°C, and 650°C. The doping profile was determined by differentialCV-measurements. Strong outdiffusion (80%) and diffusion into the bulk material was observed after annealing. The remaining
doping concentration and the diffusion constants were determined by a computer fit at 650°C. We foundD
Sb=1.8×10−13 cm2/s,D
As=9×10−14 cm2/s andD
P=4×10−14 cm2/s. Lower values of the diffusion constant were determined when the samples were covered with a SiO2 layer. 相似文献
12.
This article investigates the frequency dependence of small-signal capacitance of silicon BPW34 and BPW41 (Vishay) p-i-n photodiodes.
We show that the capacitance-frequency characteristics of these photodiodes are well-described by the Schibli and Milnes model.
The activation energy and the concentration of the dominant trap levels detected in BPW34 and BPW41 are 280–330 meV and 1.1×1012−1.2×1012 cm−3, respectively. According to the high-frequency C-V measurements, the impurity concentrations are determined to be about 5.3×1012 and 1.9×1013 cm−3 in BPW41 and BPW34, respectively using the method of ΔV/Δ(C
−2) vs. C.
相似文献
13.
H. Ryssel H. Iberl M. Bleier G. Prinke K. Haberger H. Kranz 《Applied Physics A: Materials Science & Processing》1981,24(3):197-200
The diffusion behavior of implanted arsenic in polycrystalline silicon was investigated, using backscattering and electrical
measurements. The diffusion coefficient isD=8.5×10−3 exp (−2.74/kT) for polycrystalline silicon deposited on freshly-etched silicon andD=1.66 exp (−3.22/kT) for the deposition on silicon having natural oxide. At the interface to the single-crystalline silicon,
a pile-up of arsenic occurs, which depends also on the surface treatment prior to the deposition of the polycrystalline silicon. 相似文献
14.
N. P. Dikii A. N. Dovbnya Yu. V. Lyashko D. V. Medvedev E. P. Medvedeva V. L. Uvarov K. V. Achkasov 《Technical Physics》2011,56(7):1018-1022
Nuclear physics methods are used to determine the diffusion coefficients of Na, Ca, Mn, K, and 222Rn in clinoptilolite (Sokirnitsa occurrence, Ukraine) and in natural tuff (Yucca Mountain, Nevada, United States) and in tuff
irradiated by γ-quanta (E
max = 23 MeV) to a dose of 107 Gy at a leaching temperature of 37°C. The diffusion coefficients of sodium and potassium in clinoptilolite are found to differ
considerably: 4 × 10−17 and 2 × 10−20 m2/s, respectively. This indicates the influence of aquacomplexes on the cation transfer. The diffusion coefficient of radon
in these materials is determined: in clinoptilolite it equals 2.5 × 10−12 m2/s. 相似文献
15.
M. Bryushinin V. Golubev Y. Kumzerov D. Kurdyukov I. Sokolov 《Applied physics. B, Lasers and optics》2009,95(3):489-495
We report an experimental investigation of the non-steady-state photoelectromotive force in nanostructured GaN within porous
glass and polypyrrole within chrysotile asbestos. The samples are illuminated by an oscillating interference pattern created
by two coherent light beams and the alternating current is detected as a response of the material. Dependences of the signal
amplitude versus temporal and spatial frequencies, light intensity, and temperature are studied for two wavelengths λ=442 and 532 nm. The conductivity of the GaN composite is measured: σ=(1.1–1.6)×10−10 Ω−1 cm−1 (λ=442 nm, I
0=0.045–0.19 W/cm2, T=293 K) and σ=(3.5–4.6)×10−10 Ω−1 cm−1 (λ=532 nm, I
0=2.3 W/cm2, T=249–388 K). The diffusion length of photocarriers in polypyrrole nanowires is also estimated: L
D=0.18 μm. 相似文献
16.
The integral energy spectrum of primary cosmic rays has been obtained. In the energy range (2.4×103−1.1×105 GeV), the spectrum of all nuclei is consistent with a power law of indexγ=1.55±0.06 and the flux of all nuclei is:N(⩾E
0)⋍(5.1±1.8)×10−1×E
0
−1.55
particles/cm2 sterad. sec., whereE
0 is in GeV. The spectrum of primaryα-particles in the energy range (4.4×103−4.8×104) GeV is also consistent with a power law of indexγ=1.71±0.12 and the flux is:N(⩾E
0)=(4.2±1.4)×10−1×E
0
−1.71
, particles per cm2 sterad. sec, whereE
0 is in GeV. 相似文献
17.
X. Guo Z. Y. Guo H. J. Wei H. Q. Yang Y. H. He S. S. Xie G. Y. Wu H. Q. Zhong L. Q. Li Q. L. Zhao 《Laser Physics》2010,20(9):1849-1855
The purpose of study is to quantify and compare diffusion of propylene glycol, glucose, glycerol in the human skin in vivo
noninvasively. Optical coherence tomography (OCT) was utilized in the functional imaging of optical cleaning agents for monitoring
and quantifying the permeability coefficients (PCs) of them. Our experiments showed that the permeability coefficient of 40%
propylene glycol from different subjects was averaged and found to be (2.52 ± 0.02) × 10−6 cm/s, the permeability coefficient of 40% glucose was (1.94 ± 0.05) × 10−6 cm/s, and the permeability coefficient of 40% glycerol was (1.82 ± 0.04) × 10−6 cm/s. The results indicated that the diffusion of propylene glycol solutions was faster than that of glucose solution, and
the diffusion of glucose solutions was faster than that of glycerol solutions. The dependence of the permeability on the different
hyperosmotic analytes could potentially be used in various basic science and clinical fields, such as optical clearing of
tissues and cells as well as in clinical pharmacology. 相似文献
18.
A sensitive and selective method for the trace determination of 3, 3’, 4, 4’-tetrachlorobiphenyl (PCB77) by using bovine serum
albumin (BSA) as a fluorescence probe was introduced. Under optimum conditions, the enhanced fluorescence intensity was proportional
to the concentration of polychlorinated biphenyls in the range of 8.9 × 10−8–5.0 × 10−6 mol L−1 for PCB77, and 5.0 × 10−7–5.0 × 10−6 mol L−1 for 2, 2’, 5, 5’-tetrachlorbiphenyl (PCB52). The detection limits (S/N = 3) of PCB77 and PCB52 were 2.6 × 10−8 mol L−1 and 2.9 × 10−7 mol L−1, respectively. Furthermore, the fluorescence enhancement mechanism was discussed in detail. Results indicated that fluorescence
enhancement of the system originated from the formation of BSA-PCBs complexes. In addition, PCBs were mainly bound to the
tyrosine residues in BSA molecules. 相似文献
19.
Thermophysical properties of Ni-5%Sn alloy melt 总被引:3,自引:3,他引:0
The surface tension and specific heat of Ni-5%Sn alloy melt were measured by the oscillating drop method and the drop calorimetric
method using electromagnetic levitation, respectively. The temperature coefficient of surface tension is 6.43×10−4 N·m−1K−1 within the temperature regime of 1464–1931 K. The enthalpy change was measured in the temperature range from 1461 to 1986
K, and the average specific heat was obtained as 43.03 J·mol−1K−1. Some other thermophysical properties, such as viscosity, solute diffusion coefficient, density, thermal diffusivity and
thermal conductivity of this alloy melt, were derived based on the experimentally measured surface tension and specific heat.
Using these thermophysical parameters, the relation between solute trapping and undercooling in rapidly solidified α-Ni was
calculated, and the theoretical prediction shows a good agreement with experimental data. 相似文献
20.
Attia MS Mahmoud WH Ramsis MN Khalil LH Othman AM Hashem SG Mostafa MS 《Journal of fluorescence》2011,21(4):1739-1748
A simple and sensitive spectrofluorimetric method for determination of trace amount of doxycycline hydrochloride (DC) in pharmaceutical
tablets and serum samples was developed. In ammonia buffer solution of pH 8.9 the doxycycline hydrochloride can remarkably
enhance the luminescence intensity of the Sm3+ ion in Sm3+- DC complex at λex = 400 nm. The produced luminescence intensity of Sm3+- DC complex in DMSO is in proportion to the concentration of DC and used as optical sensor for its determination. The dynamic
range for the determination of DC is 1 × 10−8 – 5 × 10−6 mol L−1 and in case of quantum yield calculations is 7 × 10−9 – 5 × 10−6 mol L−1 with detection limit of 6.5 × 10−10 mol L−1. The enhancement mechanism of the luminescence intensity in the Sm3+- DC system has been also discussed. A comparison with other spectrofluorimetric methods for tetracycline derivatives in which
Eu3+ ion is used instead of Sm3+ ion is also studied. 相似文献