Electrical transport and magnetic properties of perovskite-type electron-doped La–Pr–Mn–O epitaxial films

La_1−xPr_xMnO₃ (LPrMO) thin films have been epitaxially grown on (1 0 0)SrTiO₃ single-crystal substrates by pulsed-laser deposition. The films have a perovskite structure and give rise to the colossal magnetoresistance effect with the maximum magnetoresistance ratio of 10³% (at 240 K and 5 T). The electrical transport and magnetic properties have been investigated for the La_0.8Pr_0.2MnO₃ film with thickness 3000 Å. The results indicate that the films have quite a distinctive magnetotransport behavior compared to the bulk. The analysis of X-ray photoemission spectroscopy suggests that the valence state of Pr is 4+ in LPrMO film. Therefore, the epitaxial film is most likely an electron-doped colossal magnetoresistance system.     

Stress corrosion of silicate glass: a review

In the first section of the present paper, some examples, from the field, of the manifestations or consequences of the fatigue of silicate glass are briefly presented. In the second section, the interpretation of fatigue in terms of stress corrosion is reviewed: the role of ambient molecular water is well established. Whatever the details of the mechanism of action of water, it takes place very efficiently in the highly strained material close to the tip of a surface crack. This enables its sub-critical growth to be explained. But it does not explain many other observed effects of the environment on the mechanical behavior of silicate glass, and, in the last section, questions and issues are presented, which would still need to be investigated.     

The ferromagnetic order and the critical exponentγ of Gd monolayers and thin films on W(110)

The new application of electron-spin resonance to paramagnetic monolayers on well characterized surfaces (LEED, AES) in UHV is described. The high sensitivity of ESR is demonstrated for 10^–2 monolayers NO₂ adsorbed on Xe/Ag(111), corresponding to 10¹² detectable molecules. For monolayers of Gd(0001) on W(110) the critical exponent of the susceptibility and the ordering temperatureT _c are determined by analysing the ESR intensity and resonance field forTT _c ⁺ . Both determinations independently give a monolayerT _c of app. 271 K. The critical exponent changes from 2D to 3D Ising-values for monolayers to thicker films.     

An NMR study of thallium nitrate ion association in liquid ammonia

²⁰⁵Tl and¹H magnetic resonance frequencies have been determined for liquid ammonia solutions of TlClO₄ and TlNO₃ as a function of electrolyte concentration (5×10^–4 to 9.8 M) and temperature. The dependence of the resonance frequency on concentration suggests the presence of free, fully solvated thallium ions, ion pairs, and higher-order ion aggregates. Analysis of lowconcentration²⁰⁵Tl data between 0 and 30°C allowed the determination of TlNO₃ ion-pair association constants and thermodynamic parameters (H_A=+6.5 kcal-mole^–1, S_A=+36 e.u.). A preciptous decrease in²⁰⁵Tl resonance frequency was observed for NH₃ to TlNO₃ mole ratios below 3:1, suggesting the formula (NH₃)₃Tl⁺ NO ₃ ^– for the fully solvated, contact ion pair.     

Microstructure and magnetic properties of nanocomposite FePt/MgO and FePt/Ag films

An in-plane magnetic anisotropy of FePt film is obtained in the MgO 5 nm/FePt t nm/MgO 5 nm films (where t=5, 10 and 20 nm). Both the in-plane coercivity (H_c∥) and the perpendicular magnetic anisotropy of FePt films are increased when introducing an Ag-capped layer instead of MgO-capped layer. An in-plane coercivity is 3154 Oe for the MgO 5 nm/FePt 10 nm/MgO 5 nm film, and it can be increased to 4846 Oe as a 5 nm Ag-capped layer instead of MgO-capped layer. The transmission electron microscopy (TEM)-energy disperse spectrum (EDS) analysis shows that the Ag mainly distributed at the grain boundary of FePt, that leads the increase of the grain boundary energy, which will enhance coercivity and perpendicular magnetic anisotropy of FePt film.     

基于ICX205的网络摄像机的研究与设计

介绍了一款网络摄像机的硬件结构和软件编程.硬件结构主要由索尼的CCD ICX20SAK,Analog Devices模拟前端电路AD9923A以及Xilinx的FPGA XC3S1200E、TOKYO的JPEG压缩芯片TE3310RPF和ATMEL的ARM芯片AT91RM9200等组成.软件设计给出了AT91RM9200的驱动程序、应用程序编写方法.实验结果表明,该设计方案每秒可以采集、压缩、传输140万像素图像7.5帧,图像质量较好.     

Analysis of Factors Contributing to the Severity of Large Truck Crashes

Crashes that involved large trucks often result in immense human, economic, and social losses. To prevent and mitigate severe large truck crashes, factors contributing to the severity of these crashes need to be identified before appropriate countermeasures can be explored. In this research, we applied three tree-based machine learning (ML) techniques, i.e., random forest (RF), gradient boost decision tree (GBDT), and adaptive boosting (AdaBoost), to analyze the factors contributing to the severity of large truck crashes. Besides, a mixed logit model was developed as a baseline model to compare with the factors identified by the ML models. The analysis was performed based on the crash data collected from the Texas Crash Records Information System (CRIS) from 2011 to 2015. The results of this research demonstrated that the GBDT model outperforms other ML methods in terms of its prediction accuracy and its capability in identifying more contributing factors that were also identified by the mixed logit model as significant factors. Besides, the GBDT method can effectively identify both categorical and numerical factors, and the directions and magnitudes of the impacts of the factors identified by the GBDT model are all reasonable and explainable. Among the identified factors, driving under the influence of drugs, alcohol, and fatigue are the most important factors contributing to the severity of large truck crashes. In addition, the exists of curbs and medians and lanes and shoulders with sufficient width can prevent severe large truck crashes.     

Synthesis,Spectroscopic and Structural Aspects of Mono‐ and Diorganothallium(III) Complexes of 2, 6‐Diacetylpyridine Bis(thiosemicarbazone) (H2DAPTSC) — A New Coordination Mode of the HDAPTSC— Anion

The reaction of 2, 6‐diacetylpyridine bis(thiosemicarbazone) (H₂DAPTSC) with dimethylthallium hydroxide yielded the complexes [(TlMe₂)₂(DAPTSC)] and [TlMe₂(HDAPTSC)]. The structure of [TlMe₂(HDAPTSC)], determined by X‐ray diffractometry, exhibits a hitherto unknown coordination mode of the HDAPTSC^— anion in which its deprotonated thiosemicarbazone chain coordinates one metal atom through its sulphur and hydrazinic N atoms while a second metal atom is weakly coordinated through the S atom of the undeprotonated thiosemicarbazone chain. Each thallium atom is coordinated in both ways, with the result that the [TlMe₂(HDAPTSC)] units are linked in infinite helical chains in the direction of the b axis. When reacting with diphenylthallium(III) hydroxide, H₂DAPTSC induced a dephenylation process which led to the monophenylthallium(III) complex [TlPh(DAPTSC)]. Recrystallization from acetone yielded crystals of [TlPh(DAPTSC)]·C₃H₆O in which X‐ray diffractometry showed DAPTSC^2— to be pentadentate, coordinating through its sulphur, azomethine N and pyridine N atoms. The ¹H, ¹³C and ²⁰⁵Tl NMR data of [TlPh(DAPTSC)] indicate that its solid state molecular structure persists in DMSO solution, while those of [TlMe₂(HDAPTSC)] indicate rapid alternation between coordination of the metal atom to one of the HDAPTSC^— thiosemicarbazone chains and its coordination to the other.     

Application of Covington's nonstatistical distribution of solvate species theory to the preferential solvation of Tl+ in various binary solvent systems

Covington's nonstatistical distribution of solvate species theory of preferential solvation is used to analyze ²⁰⁵ Tl chemical shift data for 0.005M TlNO ₃ in nine binary solvent systems. The theory quite adequately fits the experimental data, and equilibrium constants and free energies of preferential solvation are obtained. The effect of choosing different values for the solvation number is investigated and found to be slight except for systems involving DMSO, ³ where decreasing the solvation number from 6 to 3 improves the fit to experimental data.