C-H···Pd(II) interaction-driven homochiral M helix formation of neutral (R,R)-bis(pyrrol-2-ylmethyl- eneamino) cyclohexane palladium(II) complex

A chiral complex of (R,R)-Pd was prepared by reaction of optically pure (R,R)-bis(pyrrol-2-ylmethyl-eneamino) cyclohexane ligand with Pd(OAc)2·2H2O under the base condition at room temperature. The weak intermolecular C-H···Pd interaction was found to be responsible for the homochiral M helix for-mation of the neutral,chiral,mononuclear (R,R)-Pd in the crystal packing.     

Temperature-sensitive gold-nanotube array membranes modified with poly（N-isopropylacrylamide）

A kind of temperature-sensitive nanotube array membrane was developed by modifying gold-nanotube array membranes with poly（N-isopropylacrylamide） （PNIPAm）. The permeation ability of the mem-branes at different temperatures was investigated using sodium fluorescein and quantum dots as probes. The results showed that the pore diameter of nanotube was changed due to the reversible response of PNIPAm-modified membranes to temperature, and then the permeation ability of the mem-branes was changed. The permeation of fluorescence probes was slow and even almost blocked at 25℃ （below the lower critical solution temperature, LCST）, since PNIPAm formed expanded structures and decreased the pore size. While at 40℃ （above the LCST）, the permeation was increased, since PNIPAm became compact structures and the pore diameter was increased. Furthermore, the permeation ability of the temperature-sensitive nanotube array membranes could be adjusted reversibly and it is possible to use the membranes in nanofluidic devices, nanogates, etc.     

Estimating divergence times among subfamilies in Nymphalidae

The mitochondrial cytochrome oxidase subunit Ⅰ （COⅠ） gene and the nuclear elongation factor 1α （EF-1α） gene were sequenced from 13 species of Nymphalidae. Phylogenetic trees of Nymphalidae, which is the largest family in butterflies, were constructed based on the sequences determined from 13 species sequenced in our laboratory and an additional 43 species obtained from GenBank using the maximum likelihood （ML） and Bayesian methods. Relative-rate tests between lineages in these phylogenetic trees were performed. On the basis of the results of the relative-rate tests and fossil information of Satyrinae, Nymphalinae and Biblidinae, the average divergence times among the subfamilies are estimated as 44.2-87.1 million years ago （Ma）. These results will be helpful for better understanding of the origin and evolution of this family, as well as the divergence time of butterflies and other complex taxa.     

High pressure effects on the crystal structure and electric conductivity of perovskite like（Ca/Sr）2CuO2Cl2 compounds

The crystal structure stability as well as electric conductance of （Sr/Ca）2CuO2Cl2 compound with K2NiF4 structure was investigated up to 31 GPa using diamond anvil technique. It seems that （Sr/Ca）2CuO2Cl2 is quite stable under pressure but with obvious anisotropic compressibility. The equation of state （EOS） obtained shows relative large bulk modulus.     

Functional analysis of the sbcD （dr1921 ） gene of the extremely radioresistant bacterium Deinococcus radiodurans

In eukaryotes, the Mre11-Rad50-Nbs1 (MRN) complex, which resides at the crossroads of DNA repair and checkpoint signaling, rapidly forms prominent foci at damage sites following double-strand break (DSB) induction. This complex carries out the initial processing of the DSB ends. Mutations in the genes that encode components of this complex result in DNA-damage hypersensitivity, genomic in- stability, telomere shortening, and aberrant meiosis. Therefore, the MR proteins are highly conserved during evolution. The bacterial orthologs of Mre11 and Rad50 are the SbcD and SbcC proteins, respec- tively. Deinococcus radiodurans, an extremely radioresistant bacterium, is able to mend hundreds of radiation-induced DSBs. The SbcD and SbcC proteins were identified as the products of the Dr1921 and Dr1922 genes. Disruption of the sbcD gene, by direct reverse-orientation insertional mutagenesis tech- nology, remarkably increases the cells’ sensitivity to various types of DNA damaging agents, such as ionizing radiation, ultraviolet irradiation, hydrogen peroxide, and mitomycin C. We also provide evidence that the drSbcD protein plays an important role in both growth and DNA repair in this organ- ism, especially in repair of DSBs generated after cellular exposure to 6000 Gy of IR. These results demonstrate that the drSbcD protein plays an important role in DSBs repair in D. radiodurans.     

Evolution of the serum resistance-associated SRA gene in African trypanosomes

Serum resistance-associated (SRA) protein, a protein unique for Trypanosoma brucei rhodesiense, is responsible for resistance of this parasite to the lysis by normal human serum (NHS) and is a vital molecular marker to distinguish this species from other African trypanosomes. We cloned and sequenced the SRA basic copy (SRAbc) gene from T. b. rhodesiense and related species and found that this gene is confined to the subgenus Trypanozoon. The average 82% identity among the sequenced SRAbc genes indicates that they may have a common origin and are highly conserved. Since SRAbc coexists in the T. b. rhodesiense genome with SRA, we propose that SRAbc might be the ‘donor VSG’, which after duplication became inserted into the expression site by recombination. Under natural selection, SRAbc could reform into SRA following mosaic formation. Supported by National Natural Science Foundation of China (Grant Nos. 30570245, 30670275), Changjiang Scholars and Innovative Research Team in University (Grant No. DPCKSCU/IRT0447), International Foundation for Science of Sweden (Grant No. B/4318-1), Grant Agency of the Czech Republic (Grant No. Z60220518) and Education Foundation of the Czech Republic (Grant No. 2B06129)     

Southwest monsoon changes indicated by oxygen isotope of ostracode shells from sediments in Qinghai Lake since the late Glacial

The δ 18O records of ostracode shells in sediments of core QH-2000 from Qinghai Lake can be used as a better proxy to reflect monsoon changes. Low monsoon precipitation between 17.5 and 11 cal. ka BP is indicated by positive δ 18O values averaging 2.37‰. A fast shift in δ 18O from positive at 11 cal. ka BP to negative at 10 cal. ka BP indicates sharp increase of monsoon precipitation. An interval of generally high monsoon precipitation is observed between 10 and 6 cal. ka BP with δ 18O values averaging -2.15‰. Decrease of monsoon precipitation between 6 and 2.5 cal. ka BP is indicated by positive δ 18O values. δ 18O keeps positive values averaging 3.0‰ between 2.5 and 0 cal. ka BP suggesting low high monsoon precipitation. The climatic changes indicated by δ 18O records of ostracode shells in sedi- ments of core QH-2000 from Qinghai Lake and our broader regional comparison show that the climate in Qinghai Lake since the late Glacial is probably controlled by southwest monsoon other than southeast monsoon.     

Applications of radiotracer techniques for the pharmacology and toxicology studies of nanomaterials

With the rapid development of nanosciences and nanotechnology, a wide variety of manufactured nanomaterials are now used in commodities, pharmaceutics, cosmetics, biomedical products, and industries. While nanomaterials possess more novel and unique physicochemical properties than bulk materials, they also have an unpredictable impact on human health. In the pharmacology and toxicology studies of nanomaterials, it is essential to know the basic behavior in vivo, i.e. absorption, distribution, metabolism, and excretion (ADME) of these newly designed materials. Radiotracer techniques are especially well suited to such studies and have got the chance to demonstrate their enchantment. In this paper, radiolabeling methods for carbon nanomaterials, metallic and metal oxide nanoparticles, etc. are summarized and the applications of the radiolabeled nanomaterials in pharmacology and toxicology studies are outlined. Supported by the National Basic Research and Development Program of China (Grant Nos. 2006CB705605 and 2006CB932505), Chinese Academy of Sciences (Grant No. KJCX3.SYW.N3), and National Natural Science Foundation of China (Grant Nos. 10525524, 10505024 and 20707027)     

A novel heteroseneous reaction for generating gaseous nitrous acid

The short-lived reactive specimen nitrous acid HONO was generated in the gas phase by the heterogeneous reaction of gaseous HCl with AgNO2 which can generate higher concentration of HONO than other methods. We investigated the process from generation to dissociation in the gas phase under different controlled temperatures, and discussed the ionization and reaction on the solid surface by combination of the photoelectron spectroscopy and photoionization mass spectroscopy （PES-PIMS） and in situ diffuse reflectance infrared Fourier transform spectroscopy （DRIFTS）.     

Superconductivity in Ba1−xSmxFFeAs and Eu1−xSmxFFeAs systems

We synthesized the samples Ba1-xSmxFFeAs and Eu1-xSmxFFeAs with ZrCuSiAs-type structure. These samples were characterized by resistivity and susceptibility. It is found that the substitution of rare earth metal for alkaline earth metal in the two systems suppresses the anomaly in resistivity and induces superconductivity. Superconductivity at 54 K in nominal composition Ba0.5Sm0.5FFeAs and at 51 K for Eu0.5Sm0.5FFeAs is realized, indicating that the superconducting transition temperatures in the iron arsenide fluorides is the same as that in oxypnictides with the same structure.     

Facile synthesis of gold nanoribbons by L-cysteine at room temperature

Highly crystalline gold nanoribbons have been synthesized via a simple method by L-cysteine reduction of aqueous chloroaurate ions at room temperature, without additional capping agent or surfactant. Based on transmission electron microscopy (TEM) and UV-vis absorption studies for the intermediate products, the formation of gold nanoribbons is regarded as a kind of oriented attachment growth. Supported by the National Natural Science Foundation of China (Grant Nos. 90406023 and 90406024), National Important Basic Research Program of China (Great Nos. 2006CB933206 and 2006CB705606) and Foundation for Top Doctoral Candidate of Southeast University.     

Detection of infrared photons with a superconductor

A superconductor single photon detector based on NbN nanowire was fabricated using electron beam lithography （EBL） and reactive ion etching （RIE） for infrared photon detection. When biased well below its critical current at 4.2 K, NbN nanowire is very sensitive to the incident photons. Typical telecommunication photons with a wavelength of 1550 nm were detected by this detector. Data analysis indicates the repeating rate of the device with 200 nm NbN nanowire may be up to 100 MHz, and the quantum efficiency is about 0,01% when biased at 0.95/c.     

Theoretic study of the reaction mechanism between （Me）3CO· radical and trans-3-hexene

The reaction mechanism between （Me）3CO· radical and trans-3-hexene in benzene was studied for the first time at the B3LYP/6-311＋＋G（d,p）//B3LYP/6-31G（d）＋ZPVE level. Two distinct elementary channels were identified as： （1） abstraction-addition; （2） addition-addition-elimination. Analysis of the potential energy surface demonstrates that for the title reaction, channels （1） and （2） have the major and minor contribution, respectively. Our calculated results can well explain the recently observed product distribution by Coseri et al. （J. Org. Chem. 2005, 70, 4629）. However, we found that the addition-abstraction channel proposed by Coseri et al. is kinetically infeasible.     

Double-side fabrication process and millimeter wave response of intrinsic Josephson junctions

We adopted double-side fabrication process to prepare intrinsic Josephson junctions (IJJs) based on Bi₂Sr₂CaCu2O_8+x (BSCCO) single crystals. Using crystal cleavage and double-side argon ion milling, we have successfully fabricated very uniform IJJs with the thickness of single crystal slice less than 200 nm. Using quasi-optical system, the response of the IJJs to millimeter wave radiation was studied. With applied magnetic field perpendicular to a-b plane, we have observed Shapiro steps under millimeter wave radiation, and the Josephson oscillation of each junction was phase-locking. Supported by the National Natural Science Foundation of China (Grant Nos. 60571007, 10778602, 60721063, 60610050), National Basic Research Program of China (Grant No. 2006CB601006) and the Fund of Jiangsu Province (Grant No. BK2007713)     

Decoration of C60 nanorods with nickel and their magnetic properties

We studied the coating of C60 nanorods with nickel by electroless plating method and investigated their magnetic properties. The morphology and structure of the nickel layer coated on C60 nanorods were characterized by transmission electron microscopy （TEM）, energy-dispersive X-ray spectroscopy （EDX）, X-ray diffraction （XRD） and Raman spectroscopy. The coated nickel is in the form of nano-sized crystals and becomes a continuous layer as reaction time increases. The hysteresis loop shows a super paramagnetic characteristic similar to that of nanometer-sized nickel particle. These results suggest that the average size of nickel particles on C60 rods is below 10 nm. Our study has shown that electroless plating is an efficient and simple method for coating C60 nanorods with nickel.     

Transfer of a eubacteria-type cell division site-determining factor CrldfnD 8ene to the nucleus from the chloroplast genome in Chlamydomonas reinhardtii

MinD is a ubiquitous ATPase that plays a crucial role in selection of the division site in eubacteria, chloroplasts, and probably Archaea. In four green algae, MesosUgma viride, Nephroselmis olivacea, Chlorella vulgaris and Prototheca wickerhamii, MinD homologues are encoded in the plastid genome. However, in Arabidopsis, MinD is a nucleus-encoded, chloroplast-targeted protein involved in chloroplast division, which suggests that MinD has been transferred to the nucleus in higher land plants. Yet the lateral gene transfer （LGT） of MinD from plastid to nucleus during plastid evolution remains poorly understood. Here, we identified a nucleus-encoded MinD homologue from unicellular green alga Chlamydomonas reinhardtii, a basal species in the green plant lineage. Overexpression of CrMinD in wild type E. coil inhibited cell division and resulted in the filamentous cell formation, clearly demonstrated the conservation of the MinD protein during the evolution of photosynthetic eukaryotes. The transient expression of CrMinD-egfp confirmed the role of CrMinD protein in the regulation of plastid division. Searching all the published plastid genomic sequences of land plants, no MinD homologues were found, which suggests that the transfer of MinD from plastid to nucleus might have occurred before the evolution of land plants.     

Genome-wide distribution of histone H3 acetylation in all- trans retinoic acid induced neuronal differentiation of SH-SY5Y cells

With chromatin immunoprecipitation (ChIP) and promoter DNA microarray analyses (ChIP-on-chip), we analyzed the variations of acetylation on histone H3 in all-trans retinoic acid (RA) induced neuronal cell differentiation. Neuroblastoma SH-SY5Y cells were treated with RA for 24 h and the acetylation on histone H3 in the promoter region of the genes was detected. Results showed that, after treatment, the level of acetylation on histone H3 elevated in 597 genes in the genome, and reduced in the other 647 genes compared with those of the control. In summary, we have successfully adopted a high throughput technique to detect and analyze variations of acetylation of histone H3 in human genome at the early phage of RA induced neuronal differentiation of the SH-SY5Y cells. Supported by National Natural Science Foundation of China (Grant Nos. 90408007 and 30721063) and National Key Basic Research and Development Program of China (Grant No. 2004CB518605)     

Study of low-pressure premixed laminar n-heptane+propane/oxygen/nitrogen flames

Low-pressure premixed laminar n-heptane+propane/oxygen/nitrogen flames were investigated with tunable synchrotron vacuum ultraviolet (VUV) photoionization and molecular-beam sampling mass spectrometry. Three flames with different mass percentage of propane in the fuel blends of 0%, 10%, and 20% were studied. The combustion intermediates were identified by comparing the measured IEs with those values in literatures. Mole fraction profiles of the main species were compared among the three flames. The experimental results provide detailed data in understanding the combustion of n-heptane and n-heptane/propane blends in engine. They are also helpful in establishing and verifying the kinetic models. Supported by the National Natural Science Foundation of China (Grant Nos. 50636040 and 50521604)     

Protein synthesis inhibition in the basolateral nucleus of amygdala facilitates extinction of auditory fear memory

It is known that consolidation of fear conditioning requires de novo protein synthesis in the amygdala. However, there is controversy about the role of protein synthesis in post-retrieval extinction of fear memory. The present study investigated the effect of protein synthesis inhibition (PSI) in the baso- lateral nucleus of amygdala (BLA) on post-retrieval extinction of auditory fear memory. Intra-BLA infu- sion of the protein synthesis inhibitor anisomycin ‘0’ h post-retrieval facilitated the extinction, but was ineffective if the memory was not retrieved. Anisomycin had no effect on the extinction when it was infused 6 h post-retrieval. The present results suggest that there exists a protein-synthesis-dependent mechanism in the BLA that retards extinction of auditory fear memory.