Electron energy band studies in polynucleotides: A review

An outline is given of the theoretical approaches that have been made to understand and describe the electronic energy band structures for polynucleotides such as DNA and RNA. The possible relevance of such studies to cancer research is also briefly described.     

The average local ionization energy as a tool for identifying reactive sites on defect-containing model graphene systems

In a continuing effort to further explore the use of the average local ionization energy $ \overline{\mathrm{I}}\left( \mathbf{r} \right) $ as a computational tool, we have investigated how well $ \overline{\mathrm{I}}\left( \mathbf{r} \right) $ computed on molecular surfaces serves as a predictive tool for identifying the sites of the more reactive electrons in several nonplanar defect-containing model graphene systems, each containing one or more pentagons. They include corannulene (C₂₀H₁₀), two inverse Stone-Thrower-Wales defect-containing structures C₂₆H₁₂ and C₄₂H₁₆, and a nanotube cap model C₂₂H₆, whose end is formed by three fused pentagons. Coronene (C₂₄H₁₂) has been included as a reference planar defect-free graphene model. We have optimized the structures of these systems as well as several monohydrogenated derivatives at the B3PW91/6-31G* level, and have computed their $ \overline{\mathrm{I}}\left( \mathbf{r} \right) $ on molecular surfaces corresponding to the 0.001 au, 0.003 au and 0.005 au contours of the electronic density. We find that (1) the convex sides of the interior carbons of the nonplanar models are more reactive than the concave sides, and (2) the magnitudes of the lowest $ \overline{\mathrm{I}}\left( \mathbf{r} \right) $ surface minima (the $ {{\overline{\mathrm{I}}}_{{\mathrm{S}\text{,}\min }}} $ ) correlate well with the interaction energies for hydrogenation at these sites. These $ {{\overline{\mathrm{I}}}_{{\mathrm{S}\text{,}\min }}} $ values decrease in magnitude as the nonplanarity of the site increases, consistent with earlier studies. A practical benefit of the use of $ \overline{\mathrm{I}}\left( \mathbf{r} \right) $ is that a single calculation suffices to characterize the numerous sites on a large molecular system, such as graphene and defect-containing graphene models.

The role of water and vegetation in the distribution of solar energy and local climate: a review

The role of plants in global climate change discussions is usually considered only in terms of the albedo and sinks/sources of CO₂ and other greenhouse gases. The main aim of this review article is to summarize the entire impact of vegetation on the climate change. It describes quantitatively the energy balance of vegetated surfaces and the effect of vegetation on the hydrological cycle. The distribution of solar energy in the landscape is dealt with in thermodynamic terms. The role of water and plants in the reduction of temperature gradients is emphasized. Papers dealing with the relationship between changes in the landscape cover and regional climates are reviewed, and the fundamental role of wetlands and forests in water cycling is outlined. Positive examples of restoration of dry landscapes, based on rainwater retention and the recovery of permanent vegetation, are described. It is recommended that the direct role of water and vegetation in cooling, reducing temperature and air pressure gradients should be included into all future recommendations for policymakers made by scientists.     

Interfacial ionization and partitioning of membrane-bound local anesthetics.

Consideration of the interfacial protonation equilibria of membrane-associated amphiphiles indicates that the partition coefficients of the protonated and unprotonated species will differ considerably. The partition coefficients of the charged and uncharged forms of spin-labelled myristic acid in dimyristoylphosphatidylcholine bilayer dispersions have been measured by EPR spectroscopy and found to be approximately 140-fold higher for the protonated acid than for the dissociated salt form. This ratio of partition coefficients is found to be in good agreement with that predicted from the interfacial shift in pKa of the fatty acid on its partitioning into the membrane. The latter was determined from the changes in the EPR spectra of the membrane-associated fatty acid with pH and was found to be +2.1 pH units. The interfacial shifts in pKa for a series of spin-labelled analogues of tertiary amine local anaesthetics have been determined from the pH dependence of the partition coefficients in dimyristoylphosphatidylcholine bilayer dispersions and are found mostly to be in the range of approx. -1.0 to -1.5 pH units, corresponding to a 10- to 30-fold higher partition coefficient of the uncharged base compared with that of the charged ammonium form.     

A metabolic view of amphibian local community structure: the role of activation energy

In the context of the metabolic theory of ecology (MTE), the activation energy (E) reflects the temperature dependence of metabolism and organism performance in different activities, such as calling behavior. In this contribution we test the role of temperature in affecting local amphibian community structure, particularly the number of species engaged in calling behavior across a temperature gradient. Toward this aim, we compiled phenological calling activity for 52 Neotropical anuran communities. For each community we estimated the activation energy of calling behavior (E), finding values significantly higher than previous reports. A wide range of methodological issues with the potential to produce overestimated E‐values were shown to have no significant effect on reported E‐values, supporting a biological interpretation of their high values and of geographic trends. Further, a path analysis related variation in E among communities with communities’ phylogenetic structure, local environmental conditions, richness, and seasonality. The decrease of activation energy at higher latitudes and less productive environments suggests that amphibians’ activity could become more dependent of internal individuals’ resources once external sources are reduced. The increase in phylogenetic attraction with latitude points to a rise in the role of niche conservatism and community filtering operating over conserved traits. Finally, flexibility in activation energy related to amphibians’ calling could be an important and poorly recognized determinant of their thermal dependence. The temporal structuring of amphians’ communities was related here with the interplay between ecological and evolutionary processes operating at different scales. Our results support the view of activation energy as an important parameter of biodiversity organization, which unravels the effects of ecological and evolutionary processes on biodiversity structure and function.     

A state space model of local energy exchange and circulatory control

Based on the assumption that the maintenance of the energy content of the living tissue was the goal of the control, a generalized model of the regulation of local circulation was developed. The goodness of the model realised on a microcomputer was verified by the good fits of simulation with various physiological reactions obtained in animal experiments that were performed in cats anaesthetized with alpha-chloralose (50 mg/kg, i.v.). The reactions were elicited by tilting the animal (45 degrees head up) and by obstructing hindlimb blood flow by means of inflation of a pressure cuff. The appropriateness of energetic considerations of the hypothesis and the properness of the construction of the model was confirmed also by the similarity of the simulated static and dynamic pressure-flow and flow-temperature characteristics, respectively, with those obtained in animal experiments reported in the literature. The performance of the model suggests that the well-known regulatory phenomena of the local circulation are the results of a set point-free control system.     

基于局地气候优化的城市蓝绿空间规划途径研究进展

在高密度、高强度的城市建设模式下,我国大中城市内部均面临着热岛效应加剧、通风能力下降、灰霾天气频发等局地气候环境问题。城市蓝绿空间作为调控城市风热环境、改善大气环境质量的关键要素,已成为城市空间规划设计领域应对局地气候问题的重要研究对象。本文通过对国内外城市蓝绿空间局地气候效应研究文献资料的回顾,从城市蓝绿空间规划布局、网络构建两个层面,梳理了冷岛景观特征优化、冷岛空间镶嵌布局、通风廊道网络连通、通风廊道界面管控的规划学途径研究进展,并总结了相关研究的主要成果及存在的主要问题,提出从智能仿真平台、评估指标体系、规划设计指南、实施保障机制4方面建立城市蓝绿空间规划应对局地气候问题的研究框架,以期为城市气候适应性规划理论创新提供有益启示。     

Invited review: Aging and energy balance.

Humans over 70 yr of age often lose weight. This appears to be due to a physiological anorexia of aging as well as a loss of lean mass (sarcopenia) and, to a lesser extent, fat mass. The causes of the physiological anorexia of aging include changes in taste and smell and a decrease in adaptive relaxation of the fundus of the stomach, which leads to more rapid antral filling and early satiation. In addition, basal and stimulated levels of the satiating hormone, cholecystokinin, are increased. In men, the decline in testosterone leads to an increase in leptin and a loss of lean mass. Although resting metabolic rate declines with aging, this is mainly due to the decline in lean body mass. Energy metabolism is also decreased due to a decline in Na+-K+-ATPase activity, decreased muscle protein turnover, and possibly changes in mitochondrial membrane protein permeability. Physical energy expenditure declines with aging. Meal-induced thermogenesis shows a delay to peak, possibly due to a delay in gastric emptying. Inadequate data are available on the effect of aging in humans on other energy-producing mechanisms such as adaptive thermogenesis. These physiological changes place older men and women at major risk of developing pathological weight loss when they develop disease states, especially those associated with cytokine elaboration.     

Microdosimetric analysis of various mammography spectra: lineal energy distributions and ionization cluster analysis

In view of recent recommendations on the frequency and the starting age of mammography screening in healthy women, it is desirable to quantify the enhanced relative biological effectiveness (RBE) of mammography X rays compared to hard X rays. While there is little doubt that the former are more potent in inducing biological damage than the latter, the magnitude of the effect is still hotly debated in the literature. We used Monte Carlo simulations and track structure analysis in micrometer and nanometer volumes to investigate differences in distributions of lineal energy and ionization clusters for a range of mammography X-ray qualities. Dose-averaged lineal energies, (yD), in breast tissue for various mammography qualities were found to result in quality factors about 40% higher than unity. Among the various mammography qualities studied, the popular molybdenum/molybdenum target/filter combination was found to have the highest (yD) in 1-microm spheres (about 5.0 keV/microm near the entrance surface of breast tissue). In 10-nm radius spheres, the mean ionization cluster order was found to be about 35% higher in mammography X rays compared to 300 keV electrons (roughly representing 60Co or 192Ir photon radiation). In even smaller spheres (2 nm radius), no significant differences were observed for the mean ionization cluster order between mammography X rays and 300 keV electrons. We conclude that the potential of mammography X rays to induce biological damage is probably not much higher than a factor of two compared to hard X rays.     

A review of life cycle assessments on wind energy systems

Purpose

Several life cycle assessments (LCAs) of wind energy published in recent years are reviewed to identify methodological differences and underlying assumptions.

Methods

A full comparative analysis of 12 studies were undertaken (ten peer-reviewed papers, one conference paper, and one industry report) regarding six fundamental factors (methods used, energy use accounting, quantification of energy production, energy performance and primary energy, natural resources, and recycling). Each factor is discussed in detail to highlight strengths and shortcomings of various approaches.

Results

Several potential issues are found concerning the way LCA methods are used for assessing energy performance and environmental impact of wind energy, as well as dealing with natural resource use and depletion. The potential to evaluate natural resource use and depletion impacts from wind energy appears to be poorly exploited or elaborated on in the reviewed studies. Estimations of energy performance and environmental impacts are critically analyzed and found to differ significantly.

Conclusions and recommendations

A continued discussion and development of LCA methodology for wind energy and other energy resources are encouraged. Efforts should be made to standardize methods and calculations. Inconsistent use of terminology and concepts among the analyzed studies are found and should be remedied. Different methods are generally used and the results are presented in diverse ways, making it difficult to compare studies with each other, but also with other renewable energy sources.     

面向低碳城市建设的建筑运行能耗驱动机理研究进展

城市快速扩张的同时,不断增大的建筑存量、建筑运行能耗及相应的碳排放成为制约城市可持续发展的重要因素.为实现节能降耗,有必要对建筑能耗碳排放的驱动机理进行深入探究.已有研究从不同角度对建筑运行能耗碳排放的影响要素和驱动机理进行了分析论证,但仍缺乏系统综述从而难以为建筑节能降耗提供全面指导.本文基于社会-经济-自然复合...     

民间药材金线莲研究动态(综述)

本文讨论金线莲的原植物、解剖特征、各地民间用法的差异,认为花叶开唇兰(Anoectochilus roxburghii)、台湾金线莲(A. formosanus)和高雄金线莲(A. koshunensis)三种应为民间金线莲常用种类;并就金线莲的工厂化生产及今后对该药用植物研究重点提出看法.     

Quantitative analysis of molecular surfaces: areas, volumes, electrostatic potentials and average local ionization energies

We describe a procedure for performing quantitative analyses of fields f(r) on molecular surfaces, including statistical quantities and locating and evaluating their local extrema. Our approach avoids the need for explicit mathematical representation of the surface and can be implemented easily in existing graphical software, as it is based on the very popular representation of a surface as collection of polygons. We discuss applications involving the volumes, surface areas and molecular surface electrostatic potentials, and local ionization energies of a group of 11 molecules.

Methods of energy extraction from microalgal biomass: a review

The potential of algal biomass as a source of liquid and gaseous biofuels is a highly topical theme, The process operations for algal biofuel production can be grouped into three areas: growth, harvesting and energy extraction, with a wide range of combinations of unit operations that can form a microalgal biofuel production system, but as yet there is no successful economically viable commercial system producing biofuel. This suggests that there are major technical and engineering difficulties to be resolved before economic algal biofuel production can be achieved. This article briefly reviews the methods by which useful energy may be extracted from microalgae biomass: (a) direct combustion, (b) pyrolysis, (c) gasification, (d) liquefaction, (e) hydrogen production by biochemical processes in certain algae, (f) fuel cells, (g) fermentation to bioethanol, (h) trans-esterification to biodiesel, (i) anaerobic digestion.     

The localization of the local anesthetic tetracaine in phospholipid vesicles: A fluorescence quenching and resonance energy transfer study

Fluorescence quenching and resonance energy transfer have been used to determine the localization of the local anesthetic tetracaine in vesicles composed of 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine (DMPC) as a function of both temperature and ionic strength. The fluorescence behaviour of tetracaine in vesicles can be attributed to its different partition coefficients in acid and basic solution, in gel phase and fluid phase vesicles, respectively. Using both steady-state and time-resolved fluorescence measurements we show that a saturable binding rather than a partitioning model holds for the interaction of tetracaine with gel phase bilayers. The relative quenching efficiencies of the series of n-AS dyes depend on the phase state of the bilayer and suggest a deeper incorporation of tetracaine in fluid phase than in gel phase membranes. Resonance energy transfer measurements support the view that tetracaine is incorporated predominantly in the region of the 9-AS chromophore in DMPC-bilayers.