High-temperature proton conductivity in acceptor-doped LaNbO4

The conductivity of acceptor-doped LaNbO₄ has been investigated in the temperature range 300 to 1200 °C as a function of the oxygen pressure and water vapor pressure by means of impedance spectroscopy and EMF measurements. The conductivity is predominantly ionic below 800 °C in air and for higher temperatures under reducing conditions. Protons are the major ionic charge carrier in the presence of water vapor. A maximum in proton conductivity of ∼ 0.001 S/cm was obtained at 950 °C in atmospheres containing ca 2% H₂O. At high temperatures (> 1000 °C) under oxidizing conditions, electron hole conduction prevails. The conductivity has been modeled assuming that oxygen vacancies and protons compensate the acceptor doping. Transport coefficients describing mobility of defects and thermodynamic constants for the incorporation of protons have been derived.     

高效液相色谱检测Zn（Ⅱ）、Cd（Ⅱ）、Co（Ⅱ）、Pb（Ⅱ）、Ni（Ⅱ）、Cu（Ⅱ）、Hg（Ⅱ）

用双-(2-羟乙基)二硫代甲酸铵(HEDC)在反相液相色谱中作检测某些金属离子的衍生化试剂，HEDC的金属螯合物微溶于水，可直接水样注射于C18柱中进行检测，范围为0．006～10mg／L相对偏差1％～2％，检测波长254nm，金属汞的整合物在HPLC分析前进行浓缩富集检测限可低至0．06～25μg／L，相对偏差小于2％。     

Determination of gentamycin by synchronous derivative fluorimetry

Use of synchronous first-derivative fluorimetry for determination of gentamycin is described. Gentamycin reacts with acetylacetone and formaldehyde in pH 5.6 HOAc/NaOAc buffer solution to form N-gentamyl-2,6-dimethyl-3,5-diacethyl-1,4-dihydropyridine[I] which is a fluorescent substance. Spectra of [I] and the reagent blank can be separated with synchronous derivative fluorimetry, and gentamycin can be determined directly. The synchronous spectral peaks of [I] and the reagent blank are at 434 and 411 nm, respectively. The first-derivative peak of [I] is at 425 nm. Effects of pH, foreign ions, buffer system, and heating time on the determination of gentamycin have been examined. The linear regression equation of the calibration graph is C=0.0513H-0.0416, with a correlation coefficient of linear regression of 0.9978. C means total potency of gentamycin: U ml(-1); H means peak height in the linear regression equation calibration graph. The linear range for the determination of gentamycin is from 0.00 to 3.00 U ml(-1). Recovery is from 95.06 to 112.0%, R.S.D. of 3.8%. The results determined by the fluorimetric method agreed roughly with those by the microbiological method. The method is simple and has low detection limit.     

Set controllability of Markov jump switching Boolean control networks and its applications

In this article, a novel method is proposed for investigating the set controllability of Markov jump switching Boolean control networks (MJSBCNs). Specifically, the switching signal is described as a discrete-time homogeneous Markov chain. By resorting to the expectation and switching indicator function, an expectation system is constructed. Based on the expectation system, a novel verifiable condition is established for solving the set reachability of MJSBCNs. With the newly obtained results on set reachability, a necessary and sufficient condition is further derived for the set controllability of MJSBCNs. The obtained results are applied to Boolean control networks with Markov jump time delays. Examples are demonstrated to justify the theoretical results.     

Use of p-dimethylaminobenzalhyde as a colored reagent for determination of procaine hydrochloride by spectrophotometry

Spectrophotometric determination of procaine hydrochloride is described. The procaine hydrochloride reacts with p-dimethylaminobenzalhyde in glacial acetic acid to form an Schiff base which is a yellow compound, and its maximum absorption wavelength is at 455nm, ₄₅₅=3.46×10⁴. The absorbance for procaine hydrochloride from 0.2 to 15 μg ml⁻¹ obeys Beer's law. The linear regression equation of the calibration graph is C=5.866A−0.02, with a linear regression correlative coefficient is 0.9994 and relative standard deviation (RSD) of 1.7%; the detection limit is 0.1 μg ml⁻¹; recovery is from 92.0 to 110.0%. Effects of reaction medium, temperature, gentamycin, beneylpenicillin, kanamycin, streptomycin, foreign ions, and stand for time on the determination of procaine hydrochloride have been examined. The results obtained by this method agreed with those by the official method (dead-stop titration). This method is rapid and simple, and can be used for the determination of procaine hydrochloride in injection solution of procaine hydrochloride.     

High resolution study of the E(0+g) → B3Π (0+u) transition (4400-4000 Å) of I2

The E → B transition of I₂ in the region 4400-4000 Å has been studied under high resolution using a 7.3 m vacuum Ebert spectrograph in the 14th order. The values of the constants B_e, α_e, γ_e, D_e and β_e of both E and B states determined from the analysis of the rotational structure of nine bands of the system are presented. Vibrational constants of the E state obtained from the analysis of all the bands so far reported and consistent with the precise constants of the B state given in previous work are also presented. The origin of the upper state, E(0⁺_g), of the transition is discussed.     

On the stability of thin epitaxial NiSi2 layers on Si (111)

By repeated deposition of several Å of Ni below 100 °C and subsequent annealing to typically 350 °C, thin continuous NiSi₂-layers have been grown epitaxially on Si (111). Thicknesses exceeding ∼- 70 Å require a different procedure due to the increasing importance of lateral growth, spoiling the layer quality. We show that MBE at substrate temperatures above 500 °C is not a viable technique to increase the thickness of the ultrathin layers. The reason is found to lie in the insufficient stability of the NiSi₂ templates, disintegrating into islands at temperatures above 500 °C. Perfectly smooth layers up to 1000 Å have, however, been grown by a new method in which alternate layers of Ni and Si (typically 1 Å and 4 Å respectively) are deposited onto the initial template at substrate temperatures between 350 °C and 380 °C.     

Factorizable and meson-pole contributions to hyperon nonleptonic decays

All vacuum-insertion contributions to hyperon nonleptonic decays can be identified within the framework of current algebra. The contribution to the s-wave amplitude has been identified by Donoghue, Golowich, Holstein, and Ponce. His pointed out that the p-wave factorizable term for the penguin operator which is not normal-ordered emerges from the disconnected contributions to the baryon poles. This separable amplitude is shown to be equivalent to the K-meson pole in the normal-ordering representation. The inclusion of a kaon pole is thus mandatory in the normal ordering scheme, but is negligible if the weak hamiltonian is not normal-ordered.     

A class of solutions in the O(3) σ-model

In a recent paper Chelnokov and Zeitlin obtained a set of differential equations for the O(3) σ-model in euclidean space and solved it under some assumption. Similar equations were obtained by Popov and Zeitlin for a ³He film and solved it under another assumption. The present note generalises the solutions obtained by these two assumptions.     

Resonant magneto-polarons in bulk GaAs

Energies of resonant polarons in GaAs, related to interaction of conduction electrons with optic phonons in the presence of a magnetic field, are calculated and compared with recent cyclotron resonance and interband magneto-optical measurements. Green's function formalism is used to describe lower and upper polaron branches for the Landau levels 1 ⩽ n ⩽ 11. Satisfying agreement between the theory and experiment is achieved for real material parameters of GaAs.