Paleoclimate change recorded in the red earth and brown-yellow sediment of Late Quaternary for northeastern part of Guangdong Province, south to the Nanling Mountains, China

The paleoenvironment indicated by the geochronology, major oxides SiO2, Al2O3 and TOFE （Fe2O3 ＋ FeO）, and CIA （Chemical Index of Alteration） value of the red earth and brown-yellow silt primarily characterized by the Linjiang stratigraphic section, based on the geological investigation of Late Quaternary along the river banks of northeastern part of China＇s Guangdong Province, south to the Nanling Mountains, allow us to hypothesize that the red earth on the first terrace in northeastern part of Guangdong belongs to reticulated red clay developed in a hot-wet environment of the last interglacial period （132-73 ka BP）, similar to the monsoon environment in the northern margin of modern tropical zone, while the overlying brown-yellow silt layer mainly accumulated in a monsoon environment of warm temperate zone in the last glacial period （73-11 ka BP）, with the aeolian sand LJ3 representing an extreme period of worsening climate. Such a hypothesis corresponds well with predecessors＇ research on the paleoenvironment indicated by abundant fossils in both south and east to the Nanling Mountains. Hence, it follows that the bioclimatic zone did experience a large and rapid vicissitude in northeastern part of China＇s Guangdong Province, and even in the full extent of the region south to the Nanling Mountains from the last interglacial period to the last glacial period, with the red earth being replaced by the brown-yellow silty sediment, and even maybe with the Ailuropoda-Stegodon Fauna being replaced by the Penghu Fauna. This study may provide an important geological demonstration for the environmental response to global change in China＇s low latitudes on a 10 ka scale.     

High resolution imaging using scanning ion conductance microscopy with improved distance feedback control

Microscopy is an essential technique for observation on living cells. There is currently great interest in apply scanning probe microscopy to image living biological cells in their natural environment at the nanometer scale. Scanning ion conductance microscopy is a new form of scanning probe microscopy, which enables non-contact high resolution imaging of living biological cells. Based on a scanned nanopipette in physiological buffer, the distance feedback control uses the ion current to control the distance between the pipette tip and the sample surface. However, this feedback control has difficulties over slopes on convoluted cell surfaces, which limits its resolution. In this study, we present an improved form of feedback control that removes the contribution of up to the third order slope from the ion current signal, hence providing a more accurate signal for controlling the distance. We show that this allows faster and lower noise topographic high resolution imaging.     

ZnO nanofluids – A potential antibacterial agent

In this work, ZnO nanofluids were produced by a medium mill with a pH value of about 7.2 and characterized by Nano-Sizer and SEM. After milling, ZnO nanofluids were formed with an average particle size of -198.4 nm. The ZnO nanofluids used for testing were stored for different periods （ 1 -, 90- and 120-day） and kept in different conditions （under the light and in the dark）. The antibacterial activities of these ZnO nanofluids were evaluated by estimating the reduction ratio of the bacteria treated with ZnO. The results showed that the ZnO nanofluid stored for 120 days under the light had the best antibacterial behavior against Escherichia coli DH5α. SEM images suggest that an interaction between the ZnO particles and the E. coli bacteria cells caused by electrostatic forces might be a mechanism.     

高技术指标：2007年度33国(地区)技术竞争力报告

文中的高技术指标（High Tech Indicators,HTI）为佐治亚理工大学发布的沿用多年的指标。数据对
比的时间段分别为1993年、1996年、1999年、2002/3年和2007年。论文给出了33个国家（地区）当前的竞争
力指标——技术排名(Technological Standing, TS), 同时提供了四个表征未来竞争力前景的主要指标——国家
发展取向指标(National Orientation, NO)、社会经济基础指标(Socio-Economic Infrastructure, SE)、技术基础指
标(Technological Infrastructure, TI)与生产能力指标(Productive Capacity, PC)。论文无意在高技术指标的结果上
多加笔墨,但是也的确注意到,中国已经取代美国占据了技术排名的首位。这一结果反映了高技术指标的特
点,更重要的是,它反映了中国过去15年的惊人发展速度。     

A critical ligamentous mechanism in the evolution of avian flight

Despite recent advances in aerodynamic, neuromuscular and kinematic aspects of avian flight and dozens of relevant fossil discoveries, the origin of aerial locomotion and the transition from limbs to wings continue to be debated. Interpreting this transition depends on understanding the mechanical interplay of forces in living birds, particularly at the shoulder where most wing motion takes place. Shoulder function depends on a balance of forces from muscles, ligaments and articular cartilages, as well as inertial, gravitational and aerodynamic loads on the wing. Here we show that the force balance system of the shoulder evolved from a primarily muscular mechanism to one in which the acrocoracohumeral ligament has a critical role. Features of the shoulder of Mesozoic birds and closely related theropod dinosaurs indicate that the evolution of flight preceded the acquisition of the ligament-based force balance system and that some basal birds are intermediate in shoulder morphology.     

Variants conferring risk of atrial fibrillation on chromosome 4q25

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia in humans and is characterized by chaotic electrical activity of the atria. It affects one in ten individuals over the age of 80 years, causes significant morbidity and is an independent predictor of mortality. Recent studies have provided evidence of a genetic contribution to AF. Mutations in potassium-channel genes have been associated with familial AF but account for only a small fraction of all cases of AF. We have performed a genome-wide association scan, followed by replication studies in three populations of European descent and a Chinese population from Hong Kong and find a strong association between two sequence variants on chromosome 4q25 and AF. Here we show that about 35% of individuals of European descent have at least one of the variants and that the risk of AF increases by 1.72 and 1.39 per copy. The association with the stronger variant is replicated in the Chinese population, where it is carried by 75% of individuals and the risk of AF is increased by 1.42 per copy. A stronger association was observed in individuals with typical atrial flutter. Both variants are adjacent to PITX2, which is known to have a critical function in left-right asymmetry of the heart.     

High-resolution structure prediction and the crystallographic phase problem

The energy-based refinement of low-resolution protein structure models to atomic-level accuracy is a major challenge for computational structural biology. Here we describe a new approach to refining protein structure models that focuses sampling in regions most likely to contain errors while allowing the whole structure to relax in a physically realistic all-atom force field. In applications to models produced using nuclear magnetic resonance data and to comparative models based on distant structural homologues, the method can significantly improve the accuracy of the structures in terms of both the backbone conformations and the placement of core side chains. Furthermore, the resulting models satisfy a particularly stringent test: they provide significantly better solutions to the X-ray crystallographic phase problem in molecular replacement trials. Finally, we show that all-atom refinement can produce de novo protein structure predictions that reach the high accuracy required for molecular replacement without any experimental phase information and in the absence of templates suitable for molecular replacement from the Protein Data Bank. These results suggest that the combination of high-resolution structure prediction with state-of-the-art phasing tools may be unexpectedly powerful in phasing crystallographic data for which molecular replacement is hindered by the absence of sufficiently accurate previous models.