Near-infrared transitions of LiNdP4O12 and LiErYP4O12

Abstract

Fluorescence transitions in LiNdP₄O₁₂: ⁴ F_3/2→⁴I_9/2 (0·90μm), ⁴F_3/2→⁴I_11/2 (1·05μm), ⁴F_3/2→⁴I_13/2 (1·32μm), ⁴F_3/2→⁴I_15/2 (1·77μm), and in LiErYP₄O₁₂: ⁴S_3/2→⁴I_11/2 (1·3μm), ⁴I_13/2→⁴I_15/2 (1·53μm), have been obtained at room temperature. The positions of the energy levels related to the excitation, nonradiative and radiative processes have been established from complementary absorption measurements. The fluorescence lifetimes of the above-mentioned transitions have been determined from single exponential decays.     

Mechanically driven grain boundary relaxation: a mechanism for cyclic hardening in nanocrystalline Ni

Molecular dynamics simulations are used to show that cyclic mechanical loading can relax the non-equilibrium grain boundary (GB) structures of nanocrystalline metals by dissipating energy and reducing the average atomic energy of the system, leading to higher strengths. The GB processes that dominate deformation in these materials allow low-energy boundary configurations to be found through kinematically irreversible structural changes during cycling, which increases the subsequent resistance to plastic deformation.     

Positron lifetime study of an Al-1.7at.% Mg-1.1at.% Cu alloy

The behaviour of vacancies during isothermal ageing following quenching of an Al-1.7at.% Mg-1.1at.% Cu alloy has been studied by positron annihilation lifetime spectroscopy. The positron lifetime parameters vary in parallel with the Vickers hardness of the alloy, suggesting simultaneous migration of vacancies and changes in the size and concentration of vacancies containing clusters and dislocation loops. The results also explain the long hardness plateau observed previously in ageing experiments carried out between 100 and 240°C in terms of a continuous growth of Mg-Cu-vacancy clusters during ageing. The vacancy concentration of the clusters increases gradually until the setting in of the cluster Guinier-Preston-Bagaryatsky zone transformation.     

整形美容外科年轻医师的人文修炼

我国整形美容外科在迅速发展的同时还存在许多弊病,为了促进学科整体健康快速发展,整形美容外科的年轻医师除了精进专业技术,还必须进行必要的人文修炼。本文介绍并分析了整形美容外科面临的五个人文困境,指出整形美容外科年轻医师具有进行人文修炼的必要性,并提出人文修炼的三条途径。     

Expectation of empowerment as a determinant of citizen participation in waste management planning1,2

Abstract: The study investigated the determinants of citizen participation in the development of a waste management plan. It was hypothesized that people would decide whether or not to participate in the planning based on the expectation of empowerment to be gained by their participation, not on the general evaluation of citizen participation. Four hundred and twenty‐four volunteers responded to a self‐report mailed survey conducted in August 2001 in Nisshin City. Nisshin City was selected as a city where the municipal government was starting to develop a basic plan for waste reduction and recycling. Major findings from the survey were: (a) the direct social benefits (i.e., making a better plan by citizen participation) were the main determinant of the general evaluation of citizen participation; and (b) expectation of personal empowerment (i.e., sense of self‐efficacy and solidarity) was the main determinant of behavioral intention to citizen participation.     

Phase transformation of germanium by processing through high-pressure torsion: strain and temperature effects

Germanium has been processed by high-pressure torsion (HPT) under a nominal pressure of 24 GPa at room temperature and cryogenic temperature. The samples processed at room temperature were composed of a diamond-cubic Ge-I phase and a metastable tetragonal Ge-III phase. The formation of Ge-III was significantly suppressed and Ge-I and an amorphous phase, in addition to a small amount of body-centred-cubic Ge-IV, appeared in the case of cryogenic HPT processing at 100 K. The Ge-IV phase gradually disappeared at room temperature. These results indicated that shear strain and thermal energy are important for promoting the formation of Ge-III.     

Essays: RELIGIOUS MEDICAL ETHICS: A Study of the Rulings of Rabbi Waldenberg

This article seeks to examine how religious ideas that are not the focus of a particular halakhic question become the crux of the ruling, thereby molding it and dictating its bias. We will attempt to demonstrate this through a study of Jewish medical ethics, based on some of the rulings of one of the greatest halakhic decisors of the previous generation: Rabbi Eliezer Yehuda Waldenberg (1915–2006). Rabbi Waldenberg molds his rulings on the basis of a religious principle asserting that the legitimacy of any medical procedure is qualified and limited. Rabbi Waldenberg rejects certain accepted medical practices, including plastic surgery, in vitro fertilization, and organ transplants. Even if these procedures are regarded by other halakhic decisors as being legitimate, for Rabbi Waldenberg they are ethically and religiously improper, and therefore they are halakhically forbidden.     

Thermal stability of nanocrystalline fcc and hcp Ni(Si) synthesized by mechanical alloying of Ni90Si10

The thermal stability of nanocrystalline fcc and hcp Ni(Si), obtained by mechanical alloying of Ni₉₀Si₁₀, has been studied. The allotropic transformation from fcc to hcp Ni(Si) is accompanied by a volume expansion of 8.6% and is observed when fcc Ni(Si) reaches a critical crystallite size of 10nm. The hcp phase transforms to stable fcc Ni(Si) at 573K. It has been identified that the lattice distortion in nanometre-sized crystallites from the equilibrium configuration and the decrease in the interfacial energy with grain refinement act as self obstacles in controlling the grain growth of nanocrystalline materials.     

Temperature dependence of the plastic flow behavior of tantalum

Nanoindention has been used to study the plastic flow behavior of bcc Ta(001) in the temperature range 25–200°C. Most notably, it is found that the shape of the load–displacement curves changes with increasing temperature. Only one large discontinuity marking the onset of plasticity is observed in room-temperature experiments, whereas multiple pop-ins separated by elastic reloading segments were observed at 200°C. Detailed analysis of the load–displacement curves indicates that the lattice resistance decreases with increasing temperature, consistent with the mobilization of screw dislocations by thermal activation. Contributions from the oxide layer and/or thermal drift can be excluded.     

On the plasticity event in metallic glass

Based on a systematic molecular dynamics analysis, this study reveals that plastic deformation of metallic glass is not through a uniform configuration change but via many localized plasticity events. These events are manifested by the atomic clusters of high kinetic energy and high strain rate, emerging even in the elastic deformation regime. The life of such a plasticity event is on the order of 10^?12?s, during which the distribution of kinetic energy follows a power law. The study shows that yielding in metallic glass occurs at the sudden surge point of the number of plasticity events. In the steady plastic deformation regime, the continuous nucleation and annihilation of the plastic events lead to a steady flow stress and stabilized total potential energy.