Kinetic investigation of <Emphasis Type="Italic">in situ</Emphasis> growth of CdMoO<Subscript>4</Subscript> nano-octahedra

CdMoO₄ nano-octahedra were grown in situ at room temperature by reverse-microemulsion. Energy evolution from this growth process was monitored using microcalorimetry. The microcalorimetric heat flow (MCHF) curve showed a characteristic endothermic peak for the initial reaction, and double discontinuous exothermic peaks for the subsequent crystal growth. Combined with complementary characterization techniques, the evolution of morphology and size of the CdMoO₄ nano-octahedra were correlated with the MCHF peaks. Calculations based on the microcalorimetric results at 298.15 K provided rate constants of 7.56×10⁻⁵ s⁻¹ for the reaction and nucleation process and 1.59×10⁻⁴ s⁻¹ for the crystallization process.     

Effect of acetazolamide on stable carbon isotope fractionation in <Emphasis Type="Italic">Chlamydomonas reinhardtii</Emphasis> and <Emphasis Type="Italic">Chlorella vulgaris</Emphasis>

The effect of extracellular carbonic anhydrase (CAex) on stable carbon isotope fractionation in algae is still unclear. The stable carbon isotope composition and algal growth in the presence and absence of the membrane-impermeable CA inhibitor acetazolamide were compared in Chlamydomonas reinhardtii and Chlorella vulgaris. The CAex of both algal species contributed about 9‰ of the stable carbon isotope fractionation and exhibited a dosage effect. Therefore, evidence in vivo that CAex leads to a larger carbon isotope fractionation of algae is presented.     

<Emphasis Type="Italic">In situ</Emphasis> characterization of natural pyrite bioleaching using electrochemical noise technique

An in situ characterization technique called electrochemical noise (ECN) was used to investigate the bioleaching of natural pyrite. ECN experiments were conducted in four active systems (sulfuric acid, ferric-ion, 9k culture medium, and bioleaching solutions). The ECN data were analyzed in both the time and frequency domains. Spectral noise impedance spectra obtained from power spectral density (PSD) plots for different systems were compared. A reaction mechanism was also proposed on the basis of the experimental data analysis. The bioleaching system exhibits the lowest noise resistance of 0.101 MΩ. The bioleaching of natural pyrite is considered to be a bio-battery reaction, which distinguishes it from chemical oxidation reactions in ferric-ion and culture-medium (9k) solutions. The corrosion of pyrite becomes more severe over time after the long-term testing of bioleaching.     

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.     

<Emphasis Type="Italic">In situ</Emphasis> generation and detection of methyl radical by voltammetry

The chemistry of free radicals is one of the advanced subjects of fundamental sciences such as biomedicine, environment protection, new energy sources and new material. The detection technique of free radicals is an essential tool for studying free radicals. Methyl radical is one of the representatives of alkyl radicals and the studies on it attract more attention. The current approaches to obtaining methyl radical are based on pulse radiolysis of organic substances that contain the methyl gro…     

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.     

<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.     

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.     

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.     

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   

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).     

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.     

In situ Re-Os isotope ages of sulfides in Hannuoba peridotitic xenoliths： Significance for the frequently-occurring mantle events beneath the North China Block

In situ Re-Os isotopes of sulfides in peridotitic xenoliths from Cenozoic Hannuoba basalts were analyzed by LAM-MC-ICPMS. The suifides developed two types of occurrences including silicate-enclosed and interstitial. In the enclosed sulfides, 187Os/188Os vary from 0.1124 to 0.1362 and 187Re/188Os from 0.0026 to 1.8027. In the interstitial ones, 187Os/188Os have a range from 0.1174 to 0.1354 and 187Re/188Os from 0.0365 to 1.4469. The oldest age, calculated by TRD for the enclosed sulfides, is 2.1 Ga. An isochron age of 2.3±1.2 Ga is obtained by five grains of enclosed sulfides and primitive mantle. The sulfides used have lower Re-Os isotopic ratio than primitive mantle. Meanwhile, an isochron age of 645±225 Ma is given by all in- terstitial sulfides and the enclosed sulfides with higher Re-Os isotopic ratio due to Re addition after man- tle formation. In addition, the model age of 1.3 Ga recorded by one interstitial sulfide, having similar TDM and TRD, should be meaningful to deep thermal event. The coexistence of different ages, revealed by in situ Re-Os isotope, indicates frequently-occurring mantle events beneath Hannuoba area.     

<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.     

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.     

Analysis of type II toxin-antitoxin genes <Emphasis Type="Italic">all</Emphasis> 3211-<Emphasis Type="Italic">asl</Emphasis> 3212 in <Emphasis Type="Italic">Anabaena</Emphasis> PCC 7120

The type II toxin-antitoxin genes are responsible for the phenotypic switch to a quasi-dormant state that enables cell survival under stresses, a similar function to heterocyst of cyanobacteria. In this paper, we particularly study the role of gene pair all3211-asl3212 under Spectinomycin stress to reveal how the type II toxin-antitoxin involved in environmental stress responses. Bioinformatics prediction shows that toxin protein gene All3211 is homologous to MazF, a member of mazEF family that encoding nucleases. We clone gene all3211-asl3212 into expression vectors to identify its molecular characteristics. Deletion mutant strains of all3211-asl3212 are selected in a tri-parental mating screen. Phenotype comparisons of mutant and wild type reveals no difference of single-deletion-mutants in pigment integrity, the sensitivity to antibiotics, and heterocyst formation. The results show that deletion mutation of single TAS gene pair all3211-asl3212 results in limited effects on the cellular growth of PCC 7120. Thus, we suggest that dosage compensating might be provided from redundant genes or bypass pathways to offset obvious phenotypic differences.     

Genetic diversity in the male-specific <Emphasis Type="Italic">SRY</Emphasis> gene of <Emphasis Type="Italic">Lepus yarkandensis</Emphasis>

Lepus yarkandensis, an endemic hare species in the Tarim Basin of China, has been suffering from habitat fragmentation due to desert expansion. To evaluate the effect of habitat fragmentation on its genetic diversity, the genetic diversity based on male-specific SRY gene marker is examined. A relatively low level of SRY genetic diversity is found compared to previous studies with mtDNA data, possibly due to the low SRY mutation rate and positive selection. Furthermore, one haplotype exists in eight populations along the Tarim River but not in many other relatively isolated populations, suggesting that habitat fragmentation may affect population divergence. Despite this, our pairwise Fst analysis shows no significant differentiation among populations, and this may be mainly caused by positive selection on the SRY gene in that 88 percent of individuals share the same haplotype. Finally, the phylogenetic analysis shows deep differentiation between L. yarkandensis and other two hare species (L. capensis and L. europaeus).     

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.