<Emphasis Type="Italic">In situ</Emphasis> boron isotope measurements of natural geological materials by LA-MC-ICP-MS

There are two main methods to determine boron isotopic composition. One is the solution method, in which boron is purified after the samples are dissolved in solution and the boron isotope ratios are determined by thermal ionization mass spectrometry (P-TIMS and N-TIMS) or multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS). The other is an in-situ analysis method, in which the in-situ boron isotopic ratios in minerals are analyzed directly using secondary ion mass spectrometry (SIMS) or laser ablation multicollector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS). In the in-situ analysis method for boron isotopes, the multifarious chemical purification and separation processes of the solution method are avoided, with increased work efficiency. In addition, the microzones and microbeddings of minerals can be analyzed in-situ to reveal the fine processes and conditions of mineral formation. In this study, using the standard-sample-bracketing (SSB) method, mass bias of the instrument and the fractionation of isotopes were calibrated, and the in-situ determination method of LA-MC-ICP-MS for boron isotopes was established. Through detailed analyses on a series of boron isotope standards and samples, a matrix effect was assessed but not detected, and the analysis results were in accordance with the formerly reported values or P-TIMS determined values, within the error range. The analytical results for IAEA B4 and IMR RB1 with relatively high boron contents were δ¹¹B = –(8.36±0.58)‰ (2σ, n=50) and δ¹¹B = –(12.96±0.97)‰ (2σ, n=57), respectively; the analytical result for IAEA B6 with relatively low boron content was δ¹¹B = –(3.29±1.12)‰ (2σ, n=35). In-situ measurements for B isotopes were performed on geological samples such as tourmaline, ulexite, ludwigite, inyoite and ascharite, with the results consistent with those determined by P-TIMS, within the error range.     

<Emphasis Type="Italic">In situ</Emphasis> synthesis of TiC reinforced Cu<Subscript>47</Subscript>Ti<Subscript>34</Subscript>Zr<Subscript>11</Subscript>Ni<Subscript>8</Subscript> bulk metallic glass composites

In situ synthesized TiC particles and β-Ti dendrites reinforced Cu47Ti34Zr11Ni8 bulk metallic glass (BMG) composite ingots were prepared by the suction casting method.The ingots with diameters from 1 up to 4mm were successfully obtained. It was shown that introducing TiC micro-sized particles into the amorphous matrix did not disturb the glass forming ability (GFA) of the matrix,while the yield strength and ductility could be well improved.The phase constitution, microstructure and elements distribution in the composites were studied by OM, XRD, SEM and EDS.It was shown that the in situ synthesized TiC particles acting as heterogeneous nucleation sites promoted the precipitation of β-Ti dendrites, resulting in the formation of the TiC particles and β-Ti dendrites co-reinforced BMG composites. The compressive tests were employed to probe the yield strength and ductility of BMG composites.     

Characterizations of <Emphasis Type="Italic">L</Emphasis><Subscript><Emphasis Type="Italic">p</Emphasis></Subscript>(<Emphasis Type="Italic">R</Emphasis>) using tight wavelet frames

In this paper,a Littlewood-Paley function characterization of the spaces L p(R),1相似文献   

Properties of a class of groups on <Emphasis Type="Italic">Z</Emphasis><Subscript><Emphasis Type="Italic">m</Emphasis></Subscript>

In this paper, we obtain the factorization of direct production and order of group GL(n, Z _m ) in a simple method. Then we generalize some properties of GL(2, Z _p ) proposed by Huppert, and prove that the group \(GL\left( {2,{Z_{{z^\lambda }}}} \right)\) is solvable. We also prove that group GL(n, Z _p ) is solvable if and only if GL(n, Z _p ) is solvable, and list the generators of groups GL(n, Z _p ) and SL(n, Z _p ). At last, we prove that PSL(2, Z _p )(p > 3) and PSL(n, Z _p )(n > 3) are simple.     

CO adsorption on electrode of Pt nanoparticles investigated by cyclic voltammetry and <Emphasis Type="Italic">in situ</Emphasis> FTIR spectroscopy

Pt nanoparticles were prepared by the chemical reduction method.The average diameter of Pt nanoparticles was determined to be 2.5nm by TEM.The electrochemical propertis of Pt nanoparticles were studied by cyclic voltammetry,In comparison with massive Pt,the oxidation current peak of CO adsorbed on Pt nanoparticles in broader.Twin adsorbates of CO on Pt nanoparticles were determined by in situ FTIRS for the first time.It has revealed that the linear and twin-bonded CO can be converted into bridge-bonded CO with the variation of electrode potential.A series of special properties of Pt nanoparticles,such as enhanced IR absorption of CO adsorbates,were also observed.     

FTIR<Emphasis Type="Italic">in situ</Emphasis> study of supersaturated solutions of MgSO<Subscript>4</Subscript> and NaClO<Subscript>4</Subscript> aerosols

The continuous sampling FTIR/AFT (aerosol flow tube) has been constructed in the present work, leading to the in situ observation of the supersaturated solutions of MgSO4 and NaCIO4 aerosols. The observation suggests that the MgSO4 aerosol show serious mass transfer limitation at low RH (relative humidity), while the NaCIO4 aerosol deliquesce without notable effect of kinetic factors. It is also shown that the v3 band of SO4^2- is very sensitive to the formation of contact ion pairs in the supersaturated solutions of MgSO4 aerosol.     

<Emphasis Type="Italic">In situ</Emphasis> FTIR investigation on phase transformations in BN nanoparticles

Fourier transformation infrared spectrum （FTIR） was employed to investigate phase transformation of nanoparticle BN, containing eBN, rBN, wBN and cBN, in which eBN and rBN are the main components. We found that part of eBN was converted into rBN at 200--350℃. At and above 400℃, eBN transformed into wBN, and some of wBN were converted into cBN simultaneously. This conclusion is supported by the results from high- resolution transmission electron microscopic （HRTEM） and Raman spectroscopic measurements. In this work, the converting processes between different BN phases were continuously monitored by in situ FTIR spectroscopy. The results will be helpful for synthesis of cBN at moderate conditions.     

Agrobacterium tumefaciens-mediated Transformation of CryⅠA(b) gene to Trichoderma harzianum

In this study, Cry ⅠA(b) gene was successfully transferred into the biocontrol fungus Trichoderma harzianum with an efficiency of 60-180 transformants per 10^6 spores by using Agrobacterium tumefaciens-mediated transformation. Putative transformants were analyzed to test the presence of Cry ⅠA(b) gene by Southern blot. Most transformants contained a single T-DNA copy. RT-PCR analysis showed that the Cry ⅠA(b) gene was transcribed. Antifungal activities and insecticidal activities of the transformants were examined. There was no obvious difference in antifungal activities between the transformants and their wild strains. The modified mortalities of the transformants T1 and T2 were 69.57% and 91.30%, respectively. The tranformation system mediated by A. tumefaciens proved to be a powerful tool for the filamentous fungi transformation and functional genomic study with its high transformation frequency, simplicity of T-DNA integration, and genetic stability of transformants.     

Biologically active <Emphasis Type="Italic">cis</Emphasis>-cinnamic acid occurs naturally in <Emphasis Type="Italic">Brassica parachinensis</Emphasis>

The biologically active cis-cinnamic acid (cis-CA) has been perceived as a synthetic plant growth regulator for decades,However,in the present study,we found that cis-CA actually exists as a naturally occurring compound in a Brassica plant,This natural growth-regulating substance presents in both the sunlight-irradiated leaf tissue and the non-irradiated root tissue ,The concentrations of cis-CA in both tissues are comparable to the bilogi-cally effective lvels of those major plant hormones,the presence of cis-CA in root tissue suggests that it may be produced through both light-dependent and -independent path-ways or it can be transproted from a plant organ to another.     

Electron density hole and quadruple structure of <Emphasis Type="Italic">B</Emphasis><Subscript><Emphasis Type="Italic">y</Emphasis></Subscript> during collisionless magnetic reconnection

In collisionless reconnection,the magnetic field near the separatrix is stronger than that around the X-line,so an electron-beam can be formed and flows toward the X-line,which leads to a decrease of the electron density near the separatrix.Having been accelerated around the X-line,the electrons flow out along the magnetic field lines in the inner side of the separatrix.A quadruple structure of the Hall magnetic field By is formed by such a current system.A 2D particle-in-cell (PIC) simulation code is used ...     

On reverses of the <Emphasis Type="Italic">L</Emphasis><Subscript><Emphasis Type="Italic">p</Emphasis></Subscript>-Busemann-Petty centroid inequality and its applications

In this paper,the reverse forms of the L p-Busemann-Petty centroid inequality are shown. As the applications of the reverse forms,we obtain the reverse forms of the L p-centroid-affine inequality and an upper bound of the isotropic constant for convex bodies.     

Development and characterization of interspecific hybrids between <Emphasis Type="Italic">Oryza sativa</Emphasis> and <Subscript>O. latifolia</Subscript> by <Subscript>in situ</Subscript> hybridization

Oryza sativa and O. latifolia belong to the AA and CCDD genomes of Oryza, respectively. In this study, interspecific hybrids of these species were obtained using the embryo rescue technique. Hybrid panicle traits, such as long awns, small grain, exoteric large purple stigma, grain shattering and dispersed panicles, resemble that of the paternal parent, O. latifolia, whereas there is obvious heterosis in such respects as plant height, tillering ability and vegetative vigor. Chromosome pairing and the genomic components of the hybrid were subsequently investigated using genomic in situ hybridization （GISH） and fluorescent in situ hybridization （FISH） analysis. Based on the mitotic metaphase chromosome numbers of the root tips investigated, the hybrid is a triploid with 36 chromosomes. The genomic constitution of the hybrid is ACD. In the meiotic metaphase Ⅰ of the hybrid pollen mother cell, poor chromosome pairing was identified and most of the chromosomes were univalent, which resulted in complete male sterility in the hybrid.     

Comparative study of Cambrian lobopods <Emphasis Type="Italic">Miraluolishania</Emphasis> and <Emphasis Type="Italic">Luolishania</Emphasis>

The rare fossil Miraluolishania described by Liu et ah from the Lower Cambrian Chengjiang Lagerstatte in 2004 is regarded as an arthropod sphinx because it bears mosaic features of both Iobopods and arthropods. The discovery of this rare transitional form offers direct fossil evidence for exploring the relationship between Iobopods and arthropods. However, some scientists consider Miraluolishania to be a junior synonym of Luolishania because the former superficially resembles the latter in general appearance. Considering the significant differences between the two taxa, a thorough comparative study of Miraluolishania and Luolishania leads to the conclusion that there are definitely two different genera. Nevertheless, the ＂Luolishania＂ of the Haikou area is indeed ＂Miraluolishania＂, whereas Luolishania is most likely the typical genus of the Maotianshan area of Chengjiang County.     

Attractiveness of tobacco volatiles induced by <Emphasis Type="Italic">Helicoverpa armigera</Emphasis> and <Emphasis Type="Italic">Helicoverpa assulta</Emphasis> to <Emphasis Type="Italic">Campoletis chlorideae</Emphasis>

The attraction of Helicoverpa armigera-and Helicoverpa assulta-induced and mechanical damage-induced tobacco volatiles to Campoletis chlorideae was investigated, and the induced volatiles were analyzed. In windtunnel, C. chlorideae was strongly attracted by herbivoreinduced tobacco volatiles. Mechanically damaged tobacco leaves, whether treated with caterpillar regurgitant or water,were more attractive to the parasitoid than undamaged tobacco leaves. GC-MS analysis revealed that only 4 compounds were released from undamaged tobacco leaves,whereas 13 compounds were commonly emitted from herbivore-infested and mechanically damaged tobacco leaves.Compound β-pinene was specifically induced by the infestation of H. armigera, and (Z)-3-hexenal was only induced by the infestation of H. armigera and H. assulta, whereas hexyl acetate was only induced by mechanical damage. Tobacco leaves infested by H. armigera and H. assulta released larger amounts of volatiles than undamaged tobacco leaves did.Tobacco leaves treated with artificial damage plus caterpillars regurgitant or water emitted the same levels of volatiles,which were higher than that emitted by undamaged tobacco leaves. The emission amounts of single compounds were also different between differently treated plants. The differences were large between herbivore-induced and mechanical damage-induced compounds, and small between H. armigeraand H.assulta-induced compounds, and among compounds emitted from mechanically damaged plants treated with water or caterpillar regurgitant.     

Genetic analysis and gene fine mapping of a rolling leaf mutant (<Emphasis Type="Italic">rl</Emphasis><Subscript><Emphasis Type="Italic">11(t)</Emphasis></Subscript>) in rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.)

The exploration of new genes controlling rice leaf shape is an important foundation for rice functional genomics and plant archi-tecture improvement. In the present study, we identified a rolling leaf mutant from indica variety Yuefeng B, named rl_11(t), which exhibited reduced plant height, rolling and narrow leaves. Leaves in rl_11(t) mutant showed abnormal number and morphology of veins compared with those in wild type plants. In addition, rl_11(t) mutant was less sensitive to the inhibitory effect of auxin than the wild type. Genetic analysis suggested that the mutant was controlled by a single recessive gene. Gene Rl_11(t) was initially mapped between SSR markers RM6089 and RM124 on chromosome 4. Thirty-two new STS markers around the Rl_11(t) region were developed for fine mapping. A physical map encompassing the Rl_11(t) locus was constructed and the target gene was finally delimited to a 31.6 kb window between STS4-25 and STS4-26 on BAC AL606645. This provides useful information for cloning of Rl_11(t) gene.     

Fermentation of xylose to produce ethanol by recombinant <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis> strain containing <Emphasis Type="Italic">XYLA</Emphasis> and <Emphasis Type="Italic">XKS1</Emphasis>

Fermentation of the pentose sugar xylose to produce ethanol using lignocellulosic biomass would make bioethanol production economically more competitive. Saccharomyce cerevisise, an efficient ethanol producer, cannot utilize xylose because it lacks the ability to convert xylose to its isomer xylulose. In this study, XYLA gene encoding xylose isomerase (XI) from Thermoanaerobacter tengcongensis MB4T and XKS1 gene encoding xylulokinase (XK) from Pichia stipitis were cloned and functionally coexpressed in Saccharomyces cerevisiae EF-326 to construct a recombinant xylose-utilizing strain. The resulting strain S. cerevisiae EF 1014 not only grew on xylose as sole carbon source, but also produced ethanol under anaerobic conditions. Fermentations performed with different xylose concentrations at different temperatures demonstrated that the highest ethanol productivity was 0.11 g/g xylose when xylose concentration was provided at 50 g/L. Under this condition, 28.4% of xylose was consumed and 1.54 g/L xylitol was formed. An increasing fermentation temperature from 30℃ to 37℃ did not improve ethanol yield.     

Cloning and expression of <Emphasis Type="Italic">AtPLC6</Emphasis>, a gene encoding a phosphatidylinositol-specific phospholipase C in <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis>

A full-length cDNA clone corresponding to a putative phosphatidylinositol-specific phospholipase C(PIPLC) was isolated from Arabidopsis thaliana by screening a cDNA library and using RT-PCR strategy.The cDNA,designated AtPLC6,encodes a putative polypeptide of 578 amino acid residues with a calculated molecular mass of 66251.84 D and a pI of 7.24. The sequence analysis indicates that the polypeptide contains X, Y, EF-hand and C2 domains.The overall structure of putative AtPLC6 protein, like other plant PI-PLCs,is most similar to that of mammalian PLCδ The recombinant AtPLC6 protein expressed in E. coil was able to hydrolyze phosphatidylinositol 4,5-biophosphate (PIP2) to generate inositol 1,4,5-trisphate (IP3) and 1,2-diacylglycerol (DAG).The protein hydrolyzes PIP2 in a Ca^2 -dependent manner and the optimum concentration of Ca^2 is 10μmol/L.These results suggested that AtPLC6 gene encodes a genuine PIPLC.Northern blot analysis showed that the AtPLC6 gene is expressed at low level in all examined tissues, such as roots,stems,leaves,flowers,siliques and seedlings under normal growth conditions.The gene is strongly induced under low temperature and weakly induced under various stresses,such as ABA, high-salt stress and heat. These results suggested that AtPLC6 might be involved in the signal-transduction pathways of cold responses of the plants.     

Preparation of PE/MMT nanocomposite by monomer intercalation and <Emphasis Type="Italic">in situ</Emphasis> copolymerization

The catalyst [(2-ArN=C(Me))₂C₅H₃N]FeCl₂ (Ar = 2-C₆H₄(i-Pr)) with methylaluminoxane (MAO) as cocatalyst was intercalated between layers of montmorillonite (MMT) for ethylene oligomerization. Metallocene catalyst Me₂Si(Ind)₂ZrCl₂ and MAO was then added to form a dual functional catalytic system. A PE/MMT nanocomposite was prepared by copolymerization of ethylene with α-olefins produced in situ from ethylene over the dual functional catalytic system. The catalytic system was of high polymeric activity. The resultant PE/MMT nanocomposites were stable and got increases in tensile strength and temperature of maximum weight loss (T_onset).