Synthesis of TiO2 nanotubes film and its light scattering property

TiO2 nanotubes with diameters of 10 nm and lengths up to 600 nm were fabricated by directly using commercial TiO2 powders P25 as the precursors via sonication-hydrothermal combination approach. TiO2 nanotubes were characterized by means of X-ray powder diffractometer （XRD）, scanning electron microscope （SEM）, selected area electron diffraction pattern （SAED） and transmission elec- tron microscope （TEM）. The light scattering property of film electrodes modified with TiO2 nanotubes was studied and revealed that TiO2 nanotubes can be used as the light scattering centers to increase the light absorption in dye-sensitized solar cells. The TiO2 nanotubes film electrodes mixed with 10% small nanoparticles TiO2 had both strong light scattering property and fine mechanical characteristics, and this kind of electrodes can be used as electrodes in improving the conversion efficiencies of dye-sensitized solar cells.     

南川金佛山植被调查报告

一、金佛山自然概况 金佛山位于28°53′N,107°27′E,四川盆地南缘川黔交接地带,属于大娄山东段的一部分。行政上属南川县所辖,在南川县城以南30余华里。山体南北长约22公里,东西宽约12公里,面积约260平方公里。     

Palaeontology: pterosaur egg with a leathery shell

The recent discovery of a pterosaur egg with embryonic skeleton and soft tissues from the Yixian Formation confirmed that the flying pterosaurs were oviparous. Here we describe another pterosaur egg whose exquisite preservation indicates that the shell structure was soft and leathery.     

Phosphorylation by aurora kinase A induces Mdm2-mediated destabilization and inhibition of p53

Aurora kinase A (also called STK15 and BTAK) is overexpressed in many human cancers. Ectopic overexpression of aurora kinase A in mammalian cells induces centrosome amplification, chromosome instability and oncogenic transformation, a phenotype characteristic of loss-of-function mutations of p53. Here we show that aurora kinase A phosphorylates p53 at Ser315, leading to its ubiquitination by Mdm2 and proteolysis. p53 is not degraded in the presence of inactive aurora kinase A or ubiquitination-defective Mdm2. Destabilization of p53 by aurora kinase A is abrogated in the presence of mutant Mdm2 that is unable to bind p53 and after repression of Mdm2 by RNA interference. Silencing of aurora kinase A results in less phosphorylation of p53 at Ser315, greater stability of p53 and cell-cycle arrest at G2-M. Cells depleted of aurora kinase A are more sensitive to cisplatin-induced apoptosis, and elevated expression of aurora kinase A abolishes this response. In a sample of bladder tumors with wild-type p53, elevated expression of aurora kinase A was correlated with low p53 concentration. We conclude that aurora kinase A is a key regulatory component of the p53 pathway and that overexpression of aurora kinase A leads to increased degradation of p53, causing downregulation of checkpoint-response pathways and facilitating oncogenic transformation of cells.     

MRS study on lentiform nucleus in idiopathic Parkinson‘s disease with unilateral symptoms

OBJECTIVE: To investigate changes in magnetic resonance spectroscopy (MRS) of lentiform nucleus during the early stage of Parkinson's disease. METHODS: Twenty-five patients with idiopathic Parkinson disease with unilateral symptoms (IPDUS) and 25 healthy volunteers were enrolled in this study. MRS of the lentiform nucleus in each patient was taken and then concentrations of N-acetylaspartate (NAA), Creatine (Cr) and Choline (Cho) were calculated. RESULTS: Compared to that in the control, NAA/ (Cho+Cr) was significantly lower in the lentiform nucleus contralateral to symptoms and even that in the ipsilateral side in IPDUS patients (all P<0.05); while there was no difference between the two sides in the healthy volunteer (P>0.05). The ratio of NAA/(Cho+Cr) ipsilateral to the sympatomatic side of the patient was also lower than that of the control (P<0.05). CONCLUSIONS: There might be some changes with MRS on the lentiform nucleus during the early stage of idiopathic Parkinson's disease with unilateral symptom. MRS may be one of the reliable methods for early or even sub-clinical diagnosis.     

The earliest known eutherian mammal

The skeleton of a eutherian (placental) mammal has been discovered from the Lower Cretaceous Yixian Formation of northeastern China. We estimate its age to be about 125 million years (Myr), extending the date of the oldest eutherian records with skull and skeleton by about 40 50 Myr. Our analyses place the new fossil at the root of the eutherian tree and among the four other known Early Cretaceous eutherians, and suggest an earlier and greater diversification of stem eutherians that occurred well before the molecular estimate for the diversification of extant placental superorders (104 64 Myr). The new eutherian has limb and foot features that are known only from scansorial (climbing) and arboreal (tree-living) extant mammals, in contrast to the terrestrial or cursorial (running) features of other Cretaceous eutherians. This suggests that the earliest eutherian lineages developed different locomotory adaptations, facilitating their spread to diverse niches in the Cretaceous.     

Experimental investigation of parallel optical data storage using pyrrylfulgide photochromic material

The optical storage characteristics of a new kind of organic photochromic material棗pyrrylfulgide were experimentally investigated in the established parallel optical data storage system. Using the pyrrylfulgide/PMMA film as a photon-mode recording medium, micro-images and encoded binary digital data were recorded, readout and erased in this parallel system. The storage density currently reaches 3?107 bit/cm2. The recorded information on the film can be kept for years in darkness at room temperature.     

Subduction and collision processes in the Central Andes constrained by converted seismic phases

The Central Andes are the Earth's highest mountain belt formed by ocean-continent collision. Most of this uplift is thought to have occurred in the past 20 Myr, owing mainly to thickening of the continental crust, dominated by tectonic shortening. Here we use P-to-S (compressional-to-shear) converted teleseismic waves observed on several temporary networks in the Central Andes to image the deep structure associated with these tectonic processes. We find that the Moho (the Mohorovici? discontinuity--generally thought to separate crust from mantle) ranges from a depth of 75 km under the Altiplano plateau to 50 km beneath the 4-km-high Puna plateau. This relatively thin crust below such a high-elevation region indicates that thinning of the lithospheric mantle may have contributed to the uplift of the Puna plateau. We have also imaged the subducted crust of the Nazca oceanic plate down to 120 km depth, where it becomes invisible to converted teleseismic waves, probably owing to completion of the gabbro-eclogite transformation; this is direct evidence for the presence of kinetically delayed metamorphic reactions in subducting plates. Most of the intermediate-depth seismicity in the subducting plate stops at 120 km depth as well, suggesting a relation with this transformation. We see an intracrustal low-velocity zone, 10-20 km thick, below the entire Altiplano and Puna plateaux, which we interpret as a zone of continuing metamorphism and partial melting that decouples upper-crustal imbrication from lower-crustal thickening.     

Estimation and prediction of black carbon emissions in Beijing City

Black carbon is a by-product of incomplete combustion of carbon containing fuels. It can alter atmospheric radiation property and make adverse impacts on human health. The energy consumption in Beijing City depends largely on coal burning. Recently, Beijing City has been performing the municipal energy structure adjustment as a tool for air pollution abatement, aiming at the air quality goal for the Beijing 2008 Olympic Games. Based on Beijing energy use data in 2000, combined with emission factors of major sources of black carbon, the emission of black carbon in Beijing City is estimated to be 7.77 Gg. Coke, raw coal and biomass as non-commercial energy are the main contributors to municipal black carbon emissions. Based on Beijing energy planning in the year 2008, the emission of black carbon in 2008 will be 2.97 Gg if the contribution from biomass is not taken into account. Assuming that the black carbon emission from rural biomass in 2008 is the same as that in 2004, the biomass burning will be the largest emitter of black carbon to Beijing City in 2008.     

Modification of the rib operon derived from Bacillus subtilis and its expression in Escherichia coli

A riboflavin operon （rib operon） derived from Bacillus subtilis 368 was modified on structure and the resulting operons were expressed in various strains of Escherichia coli. The results showed that the optimization of the rib operon and the host strain used for expression are two main factors affecting the riboflavin production. Replacing the promoterl and rfn box of the rib operon with a strong constructive promoter spol drastically increased the expression of the rib genes. When E. coli JM109 was used as the host strain, the highest riboflavin production reached 95.3μg/mL （about eight times higher than that of the unmodified r/b operon）. In addition, when tetracycline （20 μg/mL） was used as the selective pressure, compared with the ampicillin resistant transformants, a higher riboflavin yield was obtained in tetracycline resistant host strain.