Overexpression of phospholipase <Emphasis Type="Italic">D</Emphasis>α gene enhances drought and salt tolerance of <Emphasis Type="Italic">Populus tomentosa</Emphasis>

The cDNA of AtPLDa （Arabidopsis thaliana Phospholipase Da） gene was introduced into P. tomentosa （Populus tomentosa） under the control of the Cauliflower mosaic virus 35S promoter. Southern and Northern blot analyses suggested that the AtPLDa gene has been transferred into the P. tomentosa genome. No obvious morphological or developmental difference was observed between the transgenic and wild-type （WT） plants. Drought and salt tolerance and gene expression of seedlings of several transgenic lines and WT plants （control） were studied. The results showed that the rhizogenesis rate and the average root-length of transgenic lines were significantly higher than WT plants after mannitol and NaCI treatment under the same growth conditions. Northern blot analysis indicated that the higher the PLDa expression in the transgenic plants, the more tolerant the transgenic plants are to drought and salt treatment. Meanwhile, another group of these transgenic lines and WT plants （control） were treated with PEG6000 and NaCI separately. The contents of chlorophylls and the activities of some anti- oxidant enzymes （superoxide dismutase, guaiacol peroxidase and catalase） as well as malondialdehyde and relative electrical conductivity were analyzed. Altogether, our results demonstrated that overexpression of the PLDa gene can enhance the drought and salt tolerance in transgenic P. tomentosa plants.     

An α-expansin, <Emphasis Type="Italic">VfEXPA1</Emphasis>, is involved in regulation of stomatal movement in <Emphasis Type="Italic">Vicia faba</Emphasis> L.

The wall loosening of guard cells differs from other types of plant cells. However, the regulation of wall loosening during stomatal movement is poorly understood. VfEXPA1 is an α-expansin gene cloned from Vicia faba epidermal strips. Expression of VfEXPA1 is regulated by darkness and submergence, and is not affected by light and abscisic acid (ABA). In situ hybridization showed that VfEXPA1 is expressed primarily in the guard cells. Overexpression of VfEXPA1 in transgenic tobacco accelerated light-induced stomatal opening, and increased both transpiration and photosynthetic rates under favorable growth conditions. Our results indicate the guard cell-expressed expansin VfEXPA1 plays an important role in regulation of stomatal opening.     

Effect of Mg content on the structural and optical properties of Mg<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Zn<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>O alloys

Mgx Zn1–x O thin films with x = 0, 0.11, 0.28, 0.44, 0.51, and 0.65 were grown by plasma-assisted molecular beam epitaxy on (0001) sapphire substrates. X-ray diffraction measurement reveals that phase separation of the Mgx Zn1–x O films occurred at x =0.44 and 0.51. Optical absorption spectra show that the absorption edges of the films shift to high-energy side with increasing Mg contents. In resonant Raman spectra, multiple-order Raman peaks originating from ZnO-like longitudinal optical phonons were obser...     

Synthesis of <Emphasis Type="Italic">β</Emphasis>-cyclodextrin-modified carbon nanocrystals and their fluorescent behavior

Water-soluble β-cyclodextrin (β-CD)-modified carbon nanocrystals (CNCs) have been synthesized by the reaction of CNCs with mono(6-diethylenetriamino-6-deoxy)-β-CD (DETA-β-CD) and comprehensively characterized by 1H NMR, FT-IR, transmission electron microscopy (TEM) and UV-Vis. DETA-β-CD-modified CNCs (DETA-β-CD-CNCs) are luminescent, and the quantum yield is 8.41%. The photoinduced electron transfer (PET) process between DETA-β-CD-CNCs and (ferrocenylmethyl) trime-thylammonium iodide (Fc⁺) was investigated by means of fluorescence spectroscopy.     

The inhibiting effect of 1·4 recombinant P chromosome of wheat-<Emphasis Type="Italic">Agropyron cristatum</Emphasis> addition line on the <Emphasis Type="Italic">Ph</Emphasis> gene

P chromosomes may carry a genetic system that inhibits the Ph gene in wheat. Abnormal chromosome synapsis in wheat-Agropyron cristatum addition line II-21-2 (additional 1·4 recombinant P chromosome) was observed in this study. The results of cytogenetics and Ph1 gene amplification showed that the Ph1 gene was normal and the average number of quadrivalents or hexavalents was determined to be 0.41 and 0.13, respectively, in pollen-mother cells of wheat-Agropyron cristatum addition line II-21-2. The analysis o...     

Crystal structure and negative thermal expansion of solid solution Lu<Subscript>2</Subscript>W<Subscript>3−<Emphasis Type="Italic">x</Emphasis></Subscript>Mo<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>O<Subscript>12</Subscript>

A new series of solid solutions Lu₂W_3−x Mo _x O₁₂ (0.5≤x≤2.5) were successfully synthesized by the solid-state method. Their crystal structure and negative thermal expansion properties were studied using high-temperature X-ray powder diffraction and the Rietveld method. All samples of rare-earth tungstates and molybdates are found to crystallize in the same orthorhombic structure with space group Pnca and show the negative thermal expansion phenomena related to transverse vibration of bridging oxygen atoms in the structure. Thermal expansion coefficients (TEC) of Lu₂W_3−x Mo _x O₁₂ are determined as −20.0×10⁻⁶ K⁻¹ for x=0.5 and −16.1×10⁻⁶ K⁻¹ for x=2.5 but -18.6×10⁻⁶ and −16.9×10⁻⁶ K⁻¹ for unsubstituted Lu₂W₃O₁₂ and Lu₂Mo₃O₁₂ in the identical temperature range of 200 to 800°C. High-temperature X-ray diffraction (XRD) data and bond length analysis suggest that the difference between W-O and Mo-O bond is responsible for the change of TECs after the element substitution in this series of solid solutions.     

Preparation and thermal stability of Pd<Subscript>40.5</Subscript>Ni<Subscript>40.5</Subscript>Si<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>P<Subscript>19−<Emphasis Type="Italic">x</Emphasis></Subscript> bulk metallic glasses

With the addition of Si to replace some P, Pd_40.5Ni_40.5Si _x P_19−x (x=0, 2.5, 5, 9.5, 14, and 19 in atomic number fraction) bulk glassy samples with the diameter of about 5 mm were successfully prepared by use of flux treatment and water quenching technology. With the increase of Si content, the glass forming ability of Pd_40.5Ni_40.5Si _x P_19−x increases first for low Si content and then decreases for high Si content (Si≥9.5at%). The Pd_40.5Ni_40.5Si ₅ P₁₄ glassy alloy possesses the largest supercooled liquid region ΔT of 119 K, the largest reduced glass transition temperature of 0.621, and the largest γ parameter of 0.460, indicating that this glassy alloy possesses very large glass forming ability and very high thermal stability.     

First principles studies on the electronics structures of (Li<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>Me<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>)FePO<Subscript>4</Subscript> (Me=Na and Be)

Based on density functional theory (DFT) of the first-principle for cathode materials of lithium ion battery, the electronic structures of (Li_1?x Me _x )FePO₄ (Me=Na and Be, x=0–0.40) are calculated by plane wave pseudo-potential method using Cambridge serial total energy package (CASTEP) program. The calculated results show that Li-site doping can improve the electronic conductivity enormously. Doping with Na has a noticeable effect on improving its electrical conductivity. However, serious structural distortion will occur when its doping density is beyond 0.25. In view of this, the best density of doping Na is less than 0.25. Doping with Be has an inconspicuous effect on increasing its electrical conductivity and has good cyclical stability, but it cannot achieve as good results as when it is doped with Na. Therefore we cannot find a middle ground between the two proposals. Considering cost and environmental protection, it is ideal to choose Na. So this method gives a reasonable prediction to the improvement of electronic conductivity through Li-site doping in LiFePO₄ material.     

Diastereoselective addition of lithium enolate of γ-substituted α-diazoacetoacetate to <Emphasis Type="Italic">N</Emphasis>-sulfinyl imines

Highly diastereoselective addition of lithium enolate of γ-substituted α-diazoacetoacetate to chiral N-sulfinyl imines has been developed. The addition products were further subjected to photo-induced Wolff rearrangement or Rh(II)-catalyzed intramolecular N–H insertion to afford chiral 4,5-disubstituted 2-oxo and 3-oxo pyrrolidines, respectively.     

Distribution of <Emphasis Type="Italic">δ</Emphasis><Superscript>18</Superscript>O in surface snow along a transect from Zhongshan Station to Dome A,East Antarctica

Surface snow samples were collected during the 14th (1997/1998) and 24th (2007/2008) Chinese National Antarctica Research Expeditions along a transect from Zhongshan Station to Dome A. The stable oxygen isotope ratios of these samples were measured to investigate their relationships with temperature and geographical parameters (latitude, longitude, altitude and distance to the coast). The results reveal a strong positive correlation (R=0.945) between δ¹⁸O and mean annual temperature, with a gradient of 0.84‰°C ^–1, which is a little higher than that in Terre Adelie Land. Regression analyses also show that the δ¹⁸O of surface snow is strongly correlated with distance to the coast (R=0.942), latitude (R=0.942), and altitude (R=0.941). But no significant correlation was found between δ¹⁸O and longitude in study area. Altitude should be the most important factor influencing the δ¹⁸O distribution because of distinctive topography. The δ¹⁸O-altitude and T-altitude gradients along this transect are determined to be –1.1‰/100 m and 1.31°C/100 m, respectively.     

Structural dependences of the <Emphasis Type="Italic">η</Emphasis><Superscript>6</Superscript> complexes of 3-amino-9-ethylcarbazole with chromium tricarbonyl fragment on third-order optical nonlinearities

Degenerate four-wave mixing measurements, using the 35 ps pulses at 532 nm, have been employed to investigate the third-order nonlinear optical parameters of two chromium tricarbonyl complexes η6-bonded to 3-amino-9-ethylcarbazole at either the NH2-substituted aryl ring （1） or the unsubstituted ring （2） and their precursor 3-amino-9-ethylcarbazole （AECz）. The second-order hyperpolarizability y of the compounds 1 and 2 were found to be 42.9×10^-31 and 35.9×10^-31 esu, respectively, approximately one order of magnitude greater than AECz. The relation between the molecular structure and second-order hyperpolarizability of the compounds I and 2 was explored in detail based on the three-level model and the density functional theory （DFT） calculation. The theoretical results indicate that the spatial distribution of electron density has the profound role in the third-order nonlinear optical properties.     

Fatty-acids and their <Emphasis Type="Italic">δ</Emphasis><Superscript>13</Superscript>C characteristics of seep carbonates from the northern continental slope of Gulf of Mexico

Here we reported the fatty-acids and their δ¹³C values in seep carbonates collected from Green Canyon lease block 185 (GC 185; Sample GC-F) at upper continental slope (water depth: ~540 m), and Alaminos Canyon lease block 645 (GC 645; Sample AC-E) at lower continental slope (water depth: ~2200 m) of the Gulf of Mexico. More than thirty kinds of fatty acids were detected in both samples. These fatty acids are maximized at C₁₆. There is a clear even-over-odd carbon number predominance in carbon number range. The fatty acids are mainly composed of n-fatty acids, iso-/anteiso-fatty acids and terminally branched odd-numbered fatty acids (iso/anteiso). The low δ¹³C values (−39.99‰ to −32.36‰) of n-C₁₂:0, n-C₁₃:0, i-C₁₄:0 and n-C₁₄:0 suggest that they may relate to the chemosynthetic communities at seep sites. The unsaturated fatty acids n-C_18:2 and C_18:1△⁹ have the same δ¹³C values, they may originate from the Beggiatoa/Thioploca. Unlike other fatty acids, the terminally branched fatty acids (iso/anteiso) show lower δ¹³C values (as low as −63.95‰) suggesting a possible relationship to sulfate reducing bacteria, which is common during anaerobic oxidation of methane at seep sites.     

Catalytic removal of <Emphasis Type="Italic">tert</Emphasis>-butyldimethylsilyl (TBS) and tetrahydropyranyl (THP) groups from protected alcohols by NO<Superscript>+</Superscript>BF<Subscript>4</Subscript><Superscript>−</Superscript> in methanol

An effective, catalytic method has been developed to remove TBS and THP groups from protected alcohols. TBS and THP ethers were selectively cleaved using a catalytic amount of NO⁺BF₄^– (5 mol%) in methanol at room temperature.     

Analysis of components of conserved “backbone sequences” among genomes of<Emphasis Type="Italic">Shigella</Emphasis> spp. strains

Difference in the genomic compositions of prokaryotes is the basis of the diversity in their biological characters. However, besides their flora- or strain-specific genes, those floras with closer relationship in the evolution also have conserved “backbone sequences”, which reveal the marks of their origin and evolution, and these “backbone sequences” are just the basis of their elementary living abilities and common biological properties. Shigella is very closely related to E. coli in the origin and evolution, and may turn out to belong to the same genus. In this study, a microarray containing E. coli K-12 whole genome and SG01 specific ORFs is used to investigate the genomic components of four Shigella strains. The results indicate that 16%–22% K-12 ORFs sequences are not detected in the genome of Shigella strains while the genome of Shigella contains at least 2800 conserved ORFs, which compose the common “backbone sequences”. Advanced analysis indicated that the “backbone sequences” are the essential components in maintaining the normal physiological activities of intestinal bacteria. Furthermore, only 20% SGO1-specific ORFs exist in other strains simultaneously, which demonstrate the great genome heterogeneity and the genetic diversity among the strains. the first two authours made equal contribution to this work.     

Effects of foliage boron-spraying on seed yields and fatty acid composition of tree peony (<Emphasis Type="Italic">Paeonia ostii</Emphasis> ‘Feng Dan’)

The influence of the foliage boron(B)-spaying concentration on the yield and fatty acid composition of tree peony (Paeonia ostii ‘Feng Dan’) was explored in the experiment of 2014-2015. In this research, a statistically significant correlation was found between the mass concentration of foliage boron- spraying and tree peony seed yield. Maximum yield increment of tree peony seeds was obtained when the boron-spraying concentration was 4 g/L. The composition of fatty acid was analyzed by gas chromatography-mass spectrometry (GC-MS), and the main components of the fatty acid composition were quantified by internal standard method. The increase in the oil extraction rate after foliage boron-spraying nutrition of different concentration was significant and ranged between 0.04% and 11.43%. Seed oil production and oil extraction rate were also increased due to the increase of seed yields. Furthermore, foliage boron-spraying had a significant effect on the content of linolenic acid and linoleic acid in seed oil.     

Stable carbon isotopes in the shell of <Emphasis Type="Italic">Corbicula fluminea</Emphasis> (Müller 1774): Implications for understanding environmental changes in drainage basins

Dissolved inorganic carbon (DIC) is a primary constituent of the aquatic geochemistry of terrestrial ecosystems. Changes in DIC concentration and its isotopic composition are closely associated with environmental changes in the drainage basin. Thus, a better understanding of DIC may lead to improved characterization of environmental changes. Corbicula fluminea (Müller 1774), a bivalve native to southeast Asia and a dominant invasive species in many aquatic environments around the world, has the potential to record DIC information, particularly because of its sequential skeletal deposition. Analysis of the stable carbon isotope composition (δ ¹³C) of the shell and the aquatic DIC in the Xijiang River drainage basins in southern and western China allowed us to determine that changes in δ ¹³C in the skeleton significantly correlated with those of DIC (P < 0.01, r = 0.63). These results indicate that the isotopic signature of the shell reflects that δ ¹³C of the DIC in ambient water. The temporal resolution was at the seasonal scale. Metabolic effect does not change the co-variation, even though it makes the shell δ ¹³C 1.4‰ lower statistically than that of DIC. δ ¹³C of DIC in creeks of some watershed areas may experience large temporal changes characterization of these changes requires high sampling resolution of the shell. This problem makes the clams in these areas less preferable for reconstruction of environmental changes. The present findings provide the basis for recovering paleoenvironmental changes and carbon cycles in a watershed through analysis of fossil shells of C. fluminea, which are common in some lacustrine and/or riverine sediment sequences.     

Electronic properties and stabilities of methoxy-substituted Lindqvist polyoxometalates [Nb<Subscript>2</Subscript>W<Subscript>4</Subscript>O<Subscript>19</Subscript>CH<Subscript>3</Subscript>]<Superscript>3−</Superscript> by DFT

The electronic properties and stabilities of five [Nb₂W₄O₁₈OCH₃]³⁻ isomers have been investigated using a density functional theory method. The results show that the isomer with the methoxy group occupying a bridging position between two tungsten atoms (two tungsten atoms in the plane that contains two niobium atoms) in the [Nb₂W₄O₁₈OCH₃]3⁻ framework is the most stable isomer in acetonitrile. The stability of the one-electron-reduced isomers changes little. The most stable one-electron-reduced isomer has the methoxy group occupying a bridging position between niobium atoms in the [Nb₂W₄O₁₈OCH₃]⁴⁻ framework. The M-Ob (M = Nb, W; b denotes bridging) bond lengths in anions in which the metal atoms are connected by a methoxy group are longer than those in [Nb₂W₄O₁₉]⁴⁻. The highest occupied molecular orbitals (HOMO) in [Nb₂W₄O₁₉]⁴⁻ mainly delocalize over the bridging oxygen atoms of two niobium atoms and two tungsten atoms located in the equatorial plane, and the bridging oxygen atoms on the axial surface. The lowest unoccupied molecular orbitals (LUMO) of [Nb₂W₄O₁₉]⁴⁻ are mainly concentrated on the tungsten atoms and antibonding oxygen atoms. Methoxy substitution modifies the electronic properties of the [Nb₂W₄O₁₈OCH₃]³⁻ isomers. The HOMOs in the five isomers formally delocalize over the bridging oxygen atoms, which are distant from the surface containing the methoxy group and four metal atoms. The LUMOs delocalize over the d-shells of the four metal atoms that are close to the methoxy group, and the p-orbitals of oxygen. One-electron reduction occurred at the tungsten atoms, not the niobium atoms.     

A phase field study for influence of elastic energy on L1<Subscript>0</Subscript>→L1<Subscript>2</Subscript> transient ordering in Ni<Subscript>75</Subscript>Al<Subscript>17</Subscript>Zn<Subscript>8</Subscript>

The influence of the elastic energy on L1₀→L1₂ transient ordering transformation was investigated by microscopic phase field method. It is found that there are three stages experienced in atomic ordering: solute clustering+L10 short range ordering → L1₀ long range ordering → L1₂ long range ordering. Before the formation of the high ordered L1₂ phase, it has firstly taken place the transformation from matrix to L1₀ phase, and then held the L1₀→L1₂ secondary transformation. Elastic energy is proved to take little effect on the stage of short range ordering, but as the elastic energy is multiplied, it obviously shortened the course of the solute clustering, and speeded up the proceeding of the L1₀ long range ordering transition. Accordingly, the increased elastic energy also strengthens the single crystalline directionality of L1₀ phase projecting on 2D plane and makes the ordered degree of Al and Zn atoms enhanced. With the temperature elevation, Al’s and Zn’s ordered degree decreased in L10 phase.     

Synthesis of γ-Fe<Subscript>2</Subscript>O<Subscript>3</Subscript>/SiO<Subscript>2</Subscript>/Au magnetic composites for immobilization of bovine serum albumin

A method for the two-step synthesis of magnetic composites with a γ-Fe₂O₃ core, silica inner layer and numerous gold nanoparticles supported on the surface of the silica (γ-Fe₂O₃/SiO₂/Au) is described. First, thiol-functionalized γ-Fe₂O₃/SiO₂ composites and gold colloids are prepared by modifying γ-Fe₂O₃/SiO₂ composites with mercaptosilane and reduction of Au³⁺ to Au⁰ with citrate, respectively. Gold nanoparticles are then assembled on the surface of the thiol-functionalized γ-Fe₂O₃/SiO₂ composites to form γFe₂O₃/SiO₂/Au composites. The structure of the composite particles is confirmed by transmission electronic microscopy and powder X-ray diffraction. Immobilization studies with bovine serum albumin (BSA) demonstrate that the γ-Fe₂O₃/SiO₂/Au composites can be used to immobilize BSA, making them useful for biomedical and biological applications.