Heat and cold stresses in different climate zones across China: A comparison between the 20th and 21st centuries

Summer and winter discomfort in terms of heat and cold stresses in the nine major architectural climate zones and sub-zones across China in the 21st century were investigated using predictions from general circulation models for the low and medium emissions scenarios. For the six severe cold and cold climate zones in the north, reductions in cumulative cold stress outweighed the increase in cumulative heat stress resulting in an overall decreasing trend in the annual cumulative stress, and vice versa for the other three warmer climate zones in the south. Compared with the 20th century, significant reduction in the cumulative cold stress was observed across the six zones in severe cold and cold climates, ranging from 15.8 in cold-III to 42.3 in severe cold-II. There were modest increases in the cumulative heat stress from 0.3 in cold-II to 12.3 in cold-III. For the warmer climates in the south, reduction in cumulative cold stress ranged from 7.6 in hot summer and warm winter (HSWW) to 10.3 in hot summer and cold winter, while cumulative heat stress increased from 9.9 in the mild zone to 30.6 in HSWW. A reduction in cold stress would result in less winter heating and an increase in heat stress more cooling requirement.     

Reliability analysis of roof sheathing panels exposed to a hurricane wind

Light-frame wood roofs are frequently used in the US for residential and commercial construction. High wind events, such as hurricanes, may cause severe damage to these structures by breaking the roof envelope and allowing penetration of wind-driven rain. Most previous wood panel reliability studies have used static, uniform wind pressure load models and code-specified load distribution rules for analysis. This study re-estimates the reliability of roof sheathing panels exposed to a specific hurricane event using actual wind pressure data and a more refined structural analysis model. The objective is to examine the adequacy of the simplified wind load and structural analysis models used for roof panel reliability analysis. In the procedure here, panel failure behavior is modeled by individual fastener extraction from the panel as dynamic wind pressure is increased. For reliability analysis, the limit state is based on panel pull-off. The results show that the use of a refined model provides some significant differences in panel reliability found from simplified techniques.     

Enhanced Electron Mobility Due to Dopant‐Defect Pairing in Conductive ZnMgO

The increase of the band gap in Zn_1‐xMg_xO alloys with added Mg facilitates tunable control of the conduction band alignment and the Fermi‐level position in oxide‐heterostructures. However, the maximal conductivity achievable by doping decreases considerably at higher Mg compositions, which limits practical application as a wide‐gap transparent conductive oxide. In this work, first‐principles calculations and material synthesis and characterization are combined to show that the leading cause of the conductivity decrease is the increased formation of acceptor‐like compensating intrinsic defects, such as zinc vacancies (V_Zn), which reduce the free electron concentration and decrease the mobility through ionized impurity scattering. Following the expectation that non‐equilibrium deposition techniques should create a more random distribution of oppositely charged dopants and defects compared to the thermodynamic limit, the paring between dopant Ga_Zn and intrinsic defects V_Zn is studied as a means to reduce the ionized impurity scattering. Indeed, the post‐deposition annealing of Ga‐doped Zn_0.7Mg_0.3O films grown by pulsed laser deposition increases the mobility by 50% resulting in a conductivity as high as σ = 475 S cm^‐1.     

Tailoring Electron‐Transfer Barriers for Zinc Oxide/C60 Fullerene Interfaces

The interfacial electronic structure between oxide thin films and organic semiconductors remains a key parameter for optimum functionality and performance of next‐generation organic/hybrid electronics. By tailoring defect concentrations in transparent conductive ZnO films, we demonstrate the importance of controlling the electron transfer barrier at the interface with organic acceptor molecules such as C₆₀. A combination of electron spectroscopy, density functional theory computations, and device characterization is used to determine band alignment and electron injection barriers. Extensive experimental and first principles calculations reveal the controllable formation of hybridized interface states and charge transfer between shallow donor defects in the oxide layer and the molecular adsorbate. Importantly, it is shown that removal of shallow donor intragap states causes a larger barrier for electron injection. Thus, hybrid interface states constitute an important gateway for nearly barrier‐free charge carrier injection. These findings open new avenues to understand and tailor interfaces between organic semiconductors and transparent oxides, of critical importance for novel optoelectronic devices and applications in energy‐conversion and sensor technologies.     

Biomimetic Bidirectional Switchable Adhesive Inspired by the Gecko

The gecko adhesive system has attracted significant attention since the discovery that van der Waals interactions, which are always present between surfaces, are predominantly responsible for their adhesion. The unique anisotropic frictional–adhesive capabilities of the gecko adhesive system originate from complex hierarchical structures and just as importantly, the anisotropic articulation of the structures. Here, by cleverly engineering asymmetric polymeric microstructures, a reusable switchable gecko‐like adhesive can be fabricated yielding steady high adhesion ( ≈ 1.25 N/cm²) and friction ( ≈ 2.8 N/cm²) forces when actuated for “gripping”, yet release easily with minimal adhesion ( ≈ 0.34 N/cm²) and friction (≈ 0.38 N/cm²) forces during detachment or “releasing”, over multiple attachment/detachment cycles, with a relatively small normal preload of 0.16 N/cm² to initiate the adhesion. These adhesives can also be used to reversibly suspend weights from vertical (e.g., walls), and horizontal (e.g., ceilings) surfaces by simultaneously and judiciously activating anisotropic friction and adhesion forces. This design opens the way for new gecko‐like adhesive surfaces and articulation mechanisms that do not rely on intensive nanofabrication in order to recover the anisotropic tribological property of gecko adhesive pads, albeit with lower adhesive forces compared to geckos.     

Oxidative microbial degradation of 2,4,6-trinitrotoluene via 3-methyl-4,6-dinitrocatechol

A novel pathway for biodegradation of 2,4,6-trinitrotoluene (TNT) was investigated where TNT was the sole carbon, nitrogen, and energy source. Results showed the ability of microorganismsto metabolize TNT through removal of a nitro-group, oxygenation of the aromatic ring, and production of a metabolite that is typically a precursor to oxygenolytic ring cleavage. Nitrite production was observed in active systems, and TNT degradation activity was repeatable and transferable. The metabolic intermediate, 3-methyl-4,6-dinitrocatechol, was positively identified through stable isotope mass spectrometry and tandem mass spectrometry. Experimentation with 14C-TNT showed >3% 14C-labeled CO2 in active systems after 30 d exposure to microorganisms. An increasing fraction of 14C-labeled material was associated with biomass with time, where 11.41 +/- 2.91% and 17.09 +/- 1.49% of 14C was associated with biomass in active systems after 20 and 30 d, respectively, as compared with 5.68 +/- 1.33% and 6.08 +/- 1.27% in inactive systems. Parallel degradation of TNT and production of organic metabolites and nitrite were observed in shake flasks constructed with soil from historically contaminated sites, indicating that the novel pathway identified herein is disturbed in the environment. Therefore, results presented provide evidence of a previously unreported pathway for oxidative degradation of TNT.     

Corrosion of high temprature alloys in the primary circuit helium of high temperature gas cooled reactors. – Part I: Theoretical background

The interaction of Ni and Fe-Ni base alloys with the reactive impurities H₂O, CO, H₂ and CH₄ in simulated cooling gas of the primary circuit of the High Temperature Gas Cooled Reactor (HTGR) causes corrosion effects that can significantly influence the mechanical properties. Apart from the formation of surface scales (oxides, carbides or mixed oxides/carbides), structural changes of the alloys are observed; depending on gas composition, gas supply rate and test temperature, carburization or decarburization can occur. In this report it is shown that an interpretation of the basic corrosion effects is possible on the basis of a modified stability diagram for chromium provided that - the kinetics of elementary gas metal reactions are incorporated in the expressions for carbon activity and oxygen partial pressure of the atmosphere and - the gradients of the potentials across the surface scales are taken into account. The interpretation allows the derivation of the corrosion behaviour of NiCr-base alloys in different HTGR helium compositions and enables the limits for the formation of protective chromia surface scales to be given. The influence of alloying elements other than chromium can be explained qualitatively. The results can be transferred to other reactive gas mixtures, which are characterized by an oxygen partial pressure near to the dissociation pressure of the scale forming oxides.     

Humanities computing 25 years later

This paper attempts to provide an overview of the development of humanities computing during the past twenty-five years. Mention is made of the major applications of the computer to humanities disciplines, and of the most important and representative projects across the world. Joseph Raben, professor emeritus at Queens College, The City University of New York, is founding editor of Computers and the Humanities. He is currently establishing an edited computer conference, SCHOLAR.     

William A. Hunt (1903–1986).

William A. Hunt was one of our country's early scientist-clinicians. He began his career with study of a psychology that was a meld of Titchener's structuralism and Harvard's functionalism and completed it 50 years later in the field of health psychology. Hunt spent all but a few of those 50 years as a full-time teacher, at schools that included Dartmouth College, Connecticut College for Women, and Northwestern University. While doing his dissertation, he had mastered and used the structuralist's experimental method of introspection, applying it to the study of human emotion, specifically the James-Lange theory. In 1941, Hunt entered the Navy. He discerned that the screening for military duty of some 15 million women and men required an approach suited to the rapid, albeit individual, screening of large numbers of such personnel. His teaming up with a psychiatrist, Cecil Wittson, led to their joint development of a screening interview lasting one to two minutes that, with continued refinement, proved remarkably effective. Their goals as the mental health specialists participating in the medical examination conducted at this intake station were twofold: (a) to improve the efficiency of the Navy by removing those neuropsychiatric high-risk recruits who were potential psychiatric casualties if they continued in the Navy and (b) by such removal, to save these recruits the disastrous personal experience of subsequent breakdown during military duty. In his own still active research in the 1960s and 1970s Hunt continued to apply the same methods he earlier had used (in his Navy research) to the judgmental processes clinical psychologists used to identify psychological test responses that were pathognomonic of schizophrenia, mental retardation, and related forms of psychopathology. Hunt remained, until his death at age 82, an active scientist-clinician. (PsycINFO Database Record (c) 2010 APA, all rights reserved)