Fabrication and properties of aluminum silicate fibrous materials with in situ synthesized K2Ti6O13 whiskers

To improve their mechanical and thermal insulation properties,aluminum silicate fibrous materials with in situ synthesized K2Ti6O13 whiskers were prepared by firing a mixture of short aluminum silicate fibers and gel powders obtained from a sol-gel process.During the preparation process,the fiber surface was coated with K2Ti6O13 whiskers after the fibers were subjected to a heat treatment carried out at various temperatures.The effects of process parameters on the microstructure,compressive strength,and thermal conductivity were analyzed systematically.The results show that higher treatment temperatures and longer treatment durations promoted the development of K2Ti6O13 whiskers on the surface of aluminum silicate fibers;in addition,the intersection structure between whiskers modulated the morphology and volume of the multi-aperture structure among fibers,substantially increasing the fibers' compressive strength and reducing their heat conduction and convective heat transfer at high temperatures.     

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.     

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.     

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.     

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 ...     

<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.     

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.     

<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.     

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.     

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.     

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.     

Growth characteristics of directionally solidified Al<Subscript>2</Subscript>O<Subscript>3</Subscript>/YAG/ZrO<Subscript>2</Subscript> ternary hypereutectic <Emphasis Type="Italic">in situ</Emphasis> composites under ultra-high temperature gradient

Oxide eutectic ceramic in situ composites have attracted significant interest in the application of high-temperature structural materials because of their excellent high-temperature strength, oxidation and creep resistance, as well as outstanding microstructural stability. The directionally solidified ternary Al₂O₃/YAG/ZrO₂ hypereutectic in situ composite was successfully prepared by a laser zone remelting method, aiming to investigate the growth characteristic under ultra-high temperature gradient. The microstructures and phase composition of the as-solidified hypereutectic were characterized by using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). The results show that the composite presents a typical hypereutectic lamellar microstructure consisting of fine Al₂O₃ and YAG phases, and the enriched ZrO₂ phases with smaller sizes are randomly distributed at the Al₂O₃/YAG interface and in Al₂O₃ phases. Laser power and scanning rate strongly affect the sample quality and microstructure characteristic. Additionally, coarse colony microstructures were also observed, and their formation and the effect of temperature gradient on the microstructure were discussed.     

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">L</Emphasis><Subscript>2</Subscript> decay estimate of BCL equation

This paper considers linearized BCL system with viscosity which is firstly derived by J. L. Bona, T. Colin and D. Lannes for the study of motion of water waves. L ₂ decay estimate is got by means of Fourier analysis and frequency decomposition. This result plays key role in studying the global well-posedness of corresponding nonlinear system.     

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.     

Removal of NO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> by radical injection

Removal of NOx(DeNOx, NOx is the total of NO and NO2) from flue gas by radical injection has been investigated .the discharge characteristics were examined and the steady streamer corona was acquired hy adjusting the nozzle gases properly. It was Found that an increase in the voltage resulted in a decrease in the NO concentration and the concentration of the NO2 increased at tow voltages but decreased as the voltage rose to a certain level. The DeNOx efficiency increased as the applied voltage rose and reached a maximum of 70% when the voltage approached the breakdown voltage. The hypothetical mechanism of NOx removal suggested that the radicals formed in the discharge process converted the NO and NO2 into acidic species. The Monte Carlo method was used to calculate the rate coefficients and the productivity of the radicals, and then the concentrations of both NO and NO2 and the DeNOx effielencies were calculated with chemical kinetics. The calculated DeNOx efficiencies were coalparable with the experimental DeNOx efficiencies at low voltages, but were lower at high voltages.     

Glass-forming ability,microhardness, corrosion resistance,and dealloying treatment of Mg60-xCu40Ndx alloy ribbons

The influence of Nd addition on the glass-forming ability (GFA), microhardness, and corrosion resistance of Mg_60-xCu₄₀Nd_x (x=5, 10, 15, 20, and 25, at%) alloys were investigated by differential scanning calorimetry, Vickers-type hardness tests, and electrochemical methods. The results suggest that the GFA and microhardness of the amorphous alloys increase until the Nd content reaches 20at%. The corrosion potential and corrosion current density obtained from the Tafel curves indicate that the Mg₃₅Cu₄₀Nd₂₅ ternary alloy exhibits the best corrosion resistance among the investigated alloys. Notably, nanoporous copper (NPC) was synthesized through a single-step dealloying of Mg_60-xCu₄₀Nd_x (x=5, 10, 15, 20, and 25) ternary alloys in 0.04 mol·L-1 H₂SO₄ solution under free corrosion conditions. The influence of dealloying process parameters, such as dealloying time and temperature, on the microstructure of the ribbons was also studied using the surface diffusivity theory. The formation mechanism of dealloyed samples with a multilayered structure was also discussed.