The Modified Debye–Grüneisen Model for Highly Compressed Diamond

A new modification of the Debye–Grüneisen model is proposed. It takes explicitly into account the anharmonicity of phonon modes, which leads to the nonlinear dependence of energy levels on quantum numbers. The low-temperature version of this model considering anharmonic displacement of only the lowest energy levels of both longitudinal and transverse phonons is developed. This model, calibrated on results of DFT ab initio calculations, reproduces all predicted low-temperature thermodynamic properties of diamond at pressures up to 1 TPa, including the region of its negative thermal expansion.     

探索与反响

生态设计原则1)不用外界电力-真正的零耗能设计-不需要机械系统;不需要空调;不需要机械供暖2)只用当地的材料3)采用当地建设工具与建设能力4)适应可能出现的极端环境5)结构体可以利用空气动力学为自己提供新鲜空气6)吸收雨水、云雾中地水分--用组建的湿地清洁水7)结构拥有包藏宇宙的气质     

Psychotherapeutics and the problematic origins of clinical psychology in America.

The problematic place of psychotherapy within the larger history of scientific psychology is reviewed, especially in the absence of any definitive history of clinical psychology yet written. Although standard histories of psychology imply that psychotherapy was somehow derived from the tradition of German laboratory science, modern historiography reveals a dramatically different story. Personality, abnormal, social, and clinical psychology have their roots in an international psychotherapeutic alliance related more to French neurophysiology, and this alliance flourished for several decades before psychoanalysis. Reconstruction of the American contribution to this alliance, the so-called Boston school of abnormal psychology, suggests an era of medical psychology in advance of today. Note is also made of the possible misattribution of Lightner Witmer as the father of clinical psychology. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Impact of Thermal Diffusion on Densification During SPS

Spark-plasma sintering (SPS) has the potential for rapid (with heating rates reaching several hundred K/min) and efficient consolidation of a broad spectrum of powder materials. Possible mechanisms of the enhancement of consolidation in SPS versus conventional techniques of powder processing are categorized with respect to their thermal and athermal nature. This paper analyzes the influence of thermal diffusion, which is an SPS consolidation enhancement factor of a thermal nature. The Ludwig–Soret effect of thermal diffusion causes concentration gradients in two-component systems subjected to a temperature gradient. The thermal diffusion-based constitutive mechanism of sintering results from the additional driving force instigated by spatial temperature gradients, which cause vacancy diffusion. This mechanism is a commonly omitted addition to the free-surface curvature-driven diffusion considered in conventional sintering theories. The interplay of three mechanisms of material transport during SPS is considered: surface tension- and external stress-driven grain-boundary diffusion, surface tension- and external stress-driven power-law creep, and temperature gradient-driven thermal diffusion. It is shown that the effect of thermal diffusion can be significant for ceramic powder systems. Besides SPS, the results obtained are applicable to the ample range of powder consolidation techniques, which involve high local temperature gradients.
The case study conducted on the alumina powder SPS demonstrates the correlation between the modeling and experimental data. It is noted that this study considers only one of many possible mechanisms of the consolidation enhancement during SPS. Further efforts on the modeling of field-assisted powder processing are necessary.     

Influence of Mineral Admixtures on Essential Properties of Ternary Cement Blends

Two CaCO3-based materials （limestone and clamshells） and steel slag were used as mineral admixtures in cement to produce ternary blends and their influences on hydration and portlandite formation were analyzed. Additionally, mechanical properties were determined. These properties were determined using X-ray diffraction and scanning electron microscopic/energy dispersive X-ray analytical techniques as well as applying methods specified by EN （European Standards） and ASTM （American Standards for Testing and Materials）. The portlandite （Ca（OH）E） content was considerably reduced from 36.9% of reference cement to between 13.79% and 15.5%. With the water demand and setting times of the cements containing up to 10%, admixtures did not change significantly. The mechanical tests results showed that ternary blends produced 2-day strengths higher than that specified by EN 197-1 and that blends containing up to 20% admixtures can be used to produce both Class 32.5N and 42.5N cements.     

Streak spectrograph temperature analysis from electrically exploded Ni/Al nanolaminates

We report on electrically-induced heating and mixing of multilayered nickel/aluminum (Ni/Al) laminates observed by streak camera emission spectroscopy. Past experiments probing the kinetic energy of material ejected from the reaction zone indicate that additional kinetic energy originates from Ni/Al samples, presumably from exothermic mixing between the two metals. Here we examine streak spectrographs of similar experiments to determine the presence of expected elements and their temperatures. We conducted these experiments in rough vacuum, but found the emission to be dominated by argon (Ar) and nitrogen (N) lines in addition to the expected emission of Al and Ni, which were also present. Using the spectral information of Ar, we analyzed the relative intensities of four Ar peaks between 425 and 455 nm, with respect to their expected Boltzmann distributions to yield temperatures as a function of time. These temperatures were 2.24–2.59 eV for Al samples, and 2.93–3.27 eV for both Ni and Ni/Al samples, and were within estimates based on the measured electrical energy delivered to each device. The higher Ni/Al sample temperatures seemed to validate our past measurements of increased kinetic energy and the apparent rapid exothermic mixing between Ni and Al, although Ni samples yielded surprisingly high temperatures as well. These results may be important for future nanomanufacturing techniques involving localized heating from reactive Ni/Al multilayers, where the precise control of spatial temperatures may necessitate an equally precise temporal control of the reaction.     

Age of onset of first alcohol intoxication and subsequent alcohol use among urban American Indian adolescents.

The objective was to assess the effect of early onset intoxication on subsequent alcohol involvement among urban American Indian youth. The data come from the American Indian Research (AIR) project, a panel study of urban Indian youth residing in King County, Washington. Data were collected annually from the adolescent and his/her primary caregiver from the 1988–89 school year to the 1996–97 school year, providing a total of nine waves of data. Early intoxication (by age 14) was related to delinquency, family history of alcohol abuse or dependence, poverty, broken family structure, less family cohesiveness, and more family conflict. The effects of these characteristics were, therefore, partialed out in testing effects of early intoxication on later alcohol involvement. Two-part latent growth models of alcohol use and alcohol problems were specified. Effects of early onset intoxication on these trajectories, as well as lifetime alcohol abuse or dependence by the transition to young adulthood, were examined. Findings indicate that adolescents who experienced their first intoxication early (by age 14), used alcohol more heavily from the ages of 16 to 18, experienced more problems related to the alcohol's use from the ages of 16 to 18, and were more likely to have a diagnosed alcohol disorder by the final wave of data collection. Congruent with similar studies in the general population, early intoxication appears to be associated with a deleterious course of alcohol involvement during adolescence and into the transition to young adulthood among urban American Indian youth. Implications for prevention are discussed. (PsycINFO Database Record (c) 2011 APA, all rights reserved)