An exact solution for a normal point source problem

This paper presents an exact algebraic solution for a normal point source problem on elastic half-space due to impact pulse by adopting the Cagniard-Hoop method and improving Pekeris‘ partial fraction decomposition means.     

K-rich lamellar exsolution in clinopyroxene： Constraint on the depth of peridotite source at Zhimafang

The oriented lamellar K-rich exsolutions within clinopyroxene host were recognized in garnet peridotite massif at Zhimafang in the Sulu ultrahigh pressure metamorphic terrane, eastern China. EMP and TEM analyses revealed that the composition and the index of electron diffraction for this exsolution are corresponding with phlogopite, and the shape is the lamellae with 1 μm in width and 5 to 30 μm in length. Moreover, the topotaxy is that the (001) of K-rich exsolution parallels to (I00) of the clinopyroxene host. The electron diffraction analyzing shows the exsolution is of a 1M polymorphism. The high-resolution lattice fringe image displays the stack features along [001], which only a layer mineral shows. We conclude that the clinopyroxene with IM and K-rich exsolution was probably derived from mantle depths over 240 km, thus resulting from decompressional exsolution in the initial stage of slab exhumation.     

Blue emission from hydrogen-containing a-Si：H／SiO2 multilayers and the investigation of its mechanism

A series of hydrogen-containing a-Si:H/SiO2 multilayers with different a-Si:H sublayer thickness were fabricated by layer-by-layer deposition and in situ plasma oxidation in a plasma-enhanced chemical vapor deposition system (PECVD). Optical induced blue emission from the samples was observed by the naked eye at room temperature, which has never been reported in the luminescence study of Si/SiO2 multilayers up to now. Both the photoluminescence (PL) peak and the absorption edge show a blue shift as the a-Si:H sublayer thickness decreases. The origin of the blue emission and the effect of hydrogen are discussed.     

A proteomic analysis of bacterial strain<Emphasis Type="Italic">Sinorhizobium fredii</Emphasis> RT19 subjected to salt shock

Sinorhizobium fredii RT19, a strain of freeliving bacteria, was subjected to salt shock and its protein expression profiles were analyzed by differential display proteome approaches. The results of separation by two-dimensional polyacrylamide gel electrophoresis (2D PAGE) showed that the number of resolved proteins was 481, 465 and 424, corresponding to salt-free control, 5 and 50 min 1 mol/L salt treatment, respectively. Among the resolved proteins, 82 in total had altered expression in response to salt-shock stress. 26 out of the 82 proteins were induced and 23 were completely inhibited, while 12 were up-regulated and 21 down-regulated in response to salt shock. In addition, the appearance of differentially displayed proteins responding to different salt shock periods is also reported. The identity of the 26 induced proteins was revealed by matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MS) followed by database searching. Among them, 20 were assigned to proteins with known functions. Their roles in response to salt shock stress are discussed.     

The outbreak pattern of the SARS cases in Asia

The severe acute respiratory syndrome (SARS) caused tremendous damage to many Asia countries, especially China. The transmission process and outbreak pattern of SARS is still not well understood. This study aims to find a simple model to describe the outbreak pattern of SARS cases by using SARS case data commonly released by governments. The outbreak pattern of cumulative SARS cases is expected to be a logistic type because the infection will be slowed down due to the increasing control effort by people and/or due to depletion of susceptible individuals. The increase rate of SARS cases is expected to decrease with the cumulative SARS cases, as described by the traditional logistical model, which is widely used in population dynamic studies. The instantaneous rate of increases were significantly and negatively correlated with the cumulative SARS cases in mainland of China (including Beijing, Hebei, Tianjin, Shanxi,the Autonomous Region of Inner Mongolia) and Singapore. The basic reproduction number R0 in Asia ranged from 2.0 to 5.6 (except for Taiwan, China). The R0 of Hebei and Tianjin were much higher than that of Singapore, Hongkong, Beijing, Shanxi, Inner Mongolia, indicating SARS virus might have originated differently or new mutations occurred during transmission. We demonstrated that the outbreaks of SARS in many regions of Asia were wall described by the logistic model, and the control measures implemented by governments are effective. The maximum instantaneous rate of increase, basic reproductive number, and maximum cumulative SARS cases were also calculated by using the logistic model.     

Possible developmental mechanisms underlying the origin of the crown lineages of arthropods

The extraordinarily preserved, diverse arthropod fauna from the Lower Cambrian Maotianshan shale, central Yunnan (southwest China), represents different evolutionary stages stepping from stem lineages towards crown arthropods (also called euarthropods), which makes this fauna extremely significant for discussion of the origin and early diversification of the arthropods. Anatomical analyses of the Maotianshan shale arthropods strongly indicate that     

Coupled isomorphic substitution and exsolution of pyroxene,rutile, apatite and quartz in supersilicic garnet

Dissolution of pyroxene in garnet at ultrahigh pressures produces supersilicie garnet with the coupled substitutions of Si^Ⅵ M^Ⅵ= A^Ⅵ A^Ⅵ and Si^Ⅵ Na^Ⅷ=A^Ⅵ M^Ⅷ,which are enhanced by rising pressure. The supersilicic garnet and exsolution of pyroxene, rutile, apatite and quartz in garnet during decompression were found in natural rocks,pointing to the importance in studying mantle-derived rocks and ultrahigh pressure metamorphism related to plate deep subduction. Ti, P, K and H2O enters garnet via the substitutions of Ti = Si, P^Ⅵ Na^Ⅷ = Si^Ⅵ CaⅧ, Si^Ⅵ K^Ⅷ = AI^Ⅵ M^Ⅷ, and [(OH)4]^4- = [SiO4]^4- or [4H]^4 = Si^4 respectively. The possible entering of Eskola pyroxene component M0.5AlSi2O6 in clinopyroxene, together with the common pyroxene component M2Si2O6, into garnet can lead to the presence of the substitution of Si^Ⅵ 0.5□^Ⅷ= A^Ⅵ 0.5M^Ⅷ in garnet structure, which plays a key role in the exsolution of rntile, apatite and quartz in garnet. Two new breakdown reactions are thus proposed on the basis of the new coupled substitution, which can be regarded as a theoretical model for the exsolntion of the 3 minerals in garnet. The real exsolution may be a combination of several breakdown reactions.     

Persistent organic pollutants PCNs and PBDEs in sediments from coastal waters of Qingdao,Shandong Peninsula

Thirty-one congeners of polychlorinated naphthalenes (PCNs) and 21 congeners of polybrominated diphenylethers(PBDEs)in surface sediments at 5 stations and one mussel sample from Qingdao coastal waters were analyzed. The maximum contents occur at the station near the Haibo River mouth. The total PCNs contents are in the range of 212-1209 pg/g dw, dominated by tri-Cl CN. The total PBDEs contents are in the range of 117-5510 pg/g dw,dominated by tri- to hexa-BrBDEs. The local sources of PCNs are likely from combustion processes such as incinerations and coal burnings. The sources of PBDEs are molecular diffusion from the materials containing them. Except for the area near the river mouth where is affected by the sewage sludges, an important source of PCNs and PBDEs in this area is believed to be the atmospheric deposition. Mussels enrich PCNs and PBDEs relative to the sediments. The total TEQs of PCNs in mussels are lower than the total TEQs of PCBs.     

Cyclotrimerization of nitriles catalyzed by Li<Subscript>3</Subscript>N

Nitriles were unexpectedly trimerized into s-triazines or amino-pyrimidines in high yields in the presence of catalytic amount of Li3N, resulting in a simple, solvent-free and easy-to-scale-up one-pot way to synthesize s-triazines and 4-amino-pyrimidines with high yield.