Search

In the Western China, soft rocks, in particular, phyllites are very widespread. With the increase of soft rock tunnels in recent years, the secondary lining cracking of newly-built tunnels have fre...

Watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai var. lanatus] is a cross-pollinating diploid species and is one of the most important dicotyledonous plants belonging to the family Cucurbitaceae due to its high nutritional value, rapid growth, sweet and juicy taste, and refreshing nature as a summer fruit. However, the insertion–deletion (InDel) markers available for watermelon cannot satisfy the demand to identify and map resistance genes in this major crop. In this study, we have characterised and developed numerous polymorphic InDel markers using Illumina re-sequencing of a male parental line that is resistant to Fusarium wilt. In total, 25,701 potential InDel markers were identified, with a mean size of 18 bp. From these, 7,387 potential InDel markers > 10 bp were selected and tested as candidate InDel markers to locate resistance genes for map-based cloning and polymorphism analysis. We designed and synthesised 69 primer pairs using Primer 3 software. Overall, 54 primer pairs detected p...

Novel high salt superabsorbent composites were synthesised through free radical graft polymerisation of partially neutralised 2-acrylamido-2-methylpropanesulphonic acid onto attapulgite (APT) in aqueous solution using microwave irradiation. The potassium persulphate and N,N-methylene-bis-acrylamide were used as initiator and cross-linking agent respectively. The structure of the composites was characterised by the Fourier transform infrared spectroscopy (FTIR). The effect of microwave power and APT amount on water absorbency of the superabsorbent composites was investigated. The mechanism for synthesis of the superabsorbent composites was proposed. Results show that the graft copolymerisation takes place between the APT and organic monomers. The addition of an appropriate amount of APT in the composites can effectively improve the water absorbency and salt water performance of the superabsorbent composites. The water absorbency of the superabsorbent composites decreases with increasing concentrati...

SummaryPlant defensins (PDFs) are innate anti-microbial peptides that play important roles in disease resistance, particularly resistance to fungi. Two defensin-like cDNA sequences were cloned from watermelon and named ClPDF2.4 (GenBank Accession No. KC481270) and ClPDF2.5 (GenBank Accession No. KC481271). Sequence alignments showed that the encoded proteins ClPDF2.4 and ClPDF2.5 had high amino acid sequence homology (> 62%) to known Arabidopsis PDF proteins and contained a highly conserved motif of eight cysteine residues. Phylogenetic analysis indicated that both ClPDF2.4 and ClPDF2.5 belonged to the Arabidopsis PDF2 cluster and were closely-related to each other. Real-time quantitative PCR analysis revealed that the ClPDF2.4 and ClPDF2.5 genes were expressed in a wide variety of tissues, including leaves, roots, and stems. The highest level of expression of both genes was observed in leaves. The level of transcription of ClPDF2.5 was higher than that of ClPDF2.4 in stems. Gene expression profiles in re...

The joint of cubic boron nitride (CBN) grits to 0·45%C steel were obtained by using TiB2 modified Ag–Cu–Ti active filler at the brazing temperature of 920°C for the holding time of 5 min. The microstructure characteristics of the brazing interface were detected by means of optical microscope, scanning electron microscope, energy dispersion spectrometer, X-ray diffraction and microhardness measuring equipment as well. It has been found that the microstructure of Ag–Cu–Ti filler layer is significantly refined by TiB2 particles. The almost well proportioned distribution of TiB2 particles in the filler layer is realised. Negative influence of TiB2 particles has not occurred on the chemical reaction of CBN particles and the filler at elevated temperatures. Reliable joining of CBN grits to 0·45%C steel is accomplished dependent on the resultant reaction products at the brazing interface.

Thermodynamic and kinetic analysis was performed in order to study the interfacial reaction mechanism of cubic boron nitride (CBN) abrasive grains and Ti activated Ag–Cu filler alloy during high temperature brazing. Meanwhile, microstructure of the interfacial layer was experimentally detected using scanning electron microscope (SEM), energy dispersion spectrometer (EDS) and X-ray diffraction (XRD) in the present paper. The results indicate that according to the thermodynamic theory, the interfacial reaction has been proved feasible, and during brazing the special active element Ti concentrated to and reacted with the CBN abrasive to form TiB2 and TiN, which joined hard the abrasive grain and steel substrate. Furthermore, the diffusion activation energy of the growing process in the interfacial reaction layer has discovered that the layer growth largely depends on the new formed TiN under conditions of 1153–1193 K and 5–30 min.

AbstractThe synthesis and applications of black ceramic formed by recycling of industrial wastes are presented. Black ceramic was synthesised using vanadium residue, kaolin and earthenware clay as starting materials. The stable phase structures in the black ceramic include ilmenite, haematite and iolite. The V–Ti black ceramic that was produced can be used as black pigment, black tiles, infrared radiating elements and for solar absorber coatings.

The formation of Schottky potential barriers and their complex interplay with current transport across electrically active grain boundaries (GBs) give rise to many novel properties of electroceramics such as the varistor behavior. The origin of the GB electrical activity lies in the defect chemistry, and associated variations in geometry, chemistry and electronic structure at GBs. Motivated by the recent experimental results of dopant identification and spatially resolved quantification of GB charge and associated space-charge across GBs in SrTiO3, we have performed atomic-level electronic structure calculations on GBs in SrTiO3. The first-principles density-functional embedded-cluster Discrete-Variational (DV) method is used to determine charge densities and densities of states (DOS) for several idealized models of symmetrical tilt GBs in SrTiO3 which have been derived from a combination of atomistic latticestatic simulations and experimental electron microscopy analysis.

The flow and fracture of high-temperature intermetallic alloys is strongly influenced by the propagation and cross-slip of ordinary and super dislocations. One factor associated with the poor ductility of TiAl is an apparently large Peierls stress, or lattice friction stress for the glide of ordinary (1/2(110)) dislocations. This Peierls relief is intimately related to the underlying crystal and electronic structure of TiAl, and specific bonding states have been identified by some investigators as contributing to the pinning of dislocations along certain line directions. In this study we quantify the relative strength of these bonds using several complementary electronic structure methods. Aspects of the electronic structure, equilibrium lattice constants and bond energies of γ-TiAl are compared with hypothetical f.c.c. Ti as obtained by the full-potential linearized augmented-plane-wave (FLAPW) method, the DMol molecular cluster method and the linear muffin-tin orbital (LMTO) Green function (GF)...

In this paper, the compression experiments of picosecond optical pulses from a gain-switched InGaAsP distributed feedback (DFB) laser at a 1.5 μm wavelength range using a Gires-Tournois (G-T) interferometer are reported. Ultrashort optical pulses with a pulsewidth of 6.6 ps, repetition rate of 2.4 GHz, and peak power in excess of 200 mW are obtained. The compression ratio is close to 5. The explanation for the experimental results is given, and the pulse's compression characteristics of a G-T inteferometer are discussed by a computer simulation analysis.

This paper introduces a new synthesis method, based on a computation method for solving H∞-optimization problem given by Glover (1986) and a technique ofjω-axis shifting, for designing an H∞-optimal robust controller for the MIMO system. With this method we can optimize the excess stability margin under the requirement that all the poles of the nominal closed-loop system (Cl-system) be located left of the jω-axis with a required distance d and ensure asymptotic regulation and disturbance rejection for a class of system input and disturbance if the plant perturbation does not exceed the excess stability margin. Another advantage is that there are not any constraints on the poles and zeros of the plant when using this method