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To estimate the impact of crop rotation on the pathotype and genetic structure of Phythophthora sojaein fields, 372 isolates of P. sojaewere obtained from long-term localisation experimental fields in Heilongjiang Province of China. The hypocotyl inoculation method was used to characterize the virulence of P. sojaeon 13 differential cultivars, and the amplified fragment length polymorphism (AFLP) technique was used to analyze difference in the genetic structure of P. sojae.The results indicated that an abundant diversity of genetic structures and pathotypes of P. sojae, a more uniform distribution of pathotypes and less dominance of pathotypes occurred in corn-soybean and wheat-soybean rotation fields than in a continuous soybean mono-cropping field. These findings suggested that P. sojaedid not easily become the dominant race in rotation fields, which maintain disease resistance in soybean varieties. Therefore, the results of this study suggested that Phytophthora stem and root rot of soybeans could be effectively controlled by rotating soybeans with non-host crops of corn and wheat.

The dipole polarizabilities, dipole hyperpolarizabilities, quadrupole moments, and quadrupole polarizabilities of the 5s² ¹S and 5s5p ³P0 states of In+ and Sr are calculated by using the finite-field method. The electron correlation effect and the basis set convergence are investigated in the relativistic coupled-cluster and configuration interaction calculations in order to obtain polarizabilities of high accuracy. Comparative study of the fully and scalar relativistic calculations reveals the effect of the spin-orbit coupling on the dipole polarizabilities of In+ and Sr. The blackbody-radiation shifts of the clock transition 5s² ¹S0-5.s5 f p ³Po0 due to the dipole polarizabilities, quadrupole polarizabilities, and dipole hyperpolarizabilities are evaluated to be 0.017, 8.33x10-10, and 1.93x10-17 Hz for In+ and 2.09 and 5.82x10-8, and 1.69x10-15 Hz for Sr. The blackbody-radiation shifts from the quadrupole polarizabilities and dipole hyperpolarizabilities are significantly less than that from the dipole polarizabilities and therefore can be safely omitted for the quoted 10-18 uncertainty of the optical frequency standard of In+ and Sr. [ABSTRACT FROM AUTHOR]

In this study, accurate static dipole polarizability and hyperpolarizability are calculated for Al+ ground state 3s² ¹S0 and excited state 3s3p ³PJ with J=0,1,2 . The finite-field computations use energies obtained with the relativistic configuration interaction approach and the relativistic coupled-cluster approach. Excellent agreement with previously recommended values is found for the dipole polarizability of Al+ ground state 3s2 ¹S0 and excited state 3s3p ³P0 as well as the hyperpolarizability of the ground state 3s 2 ¹S0 . The recommended values of the dipole polarizability of the Al+ 3s3p ³P1 and ³P2 and the hyperpolarizability of Al+ 3s3p ³P0, ³P1, and ³P2 are also given. The impacts of the relativity and spin-orbit coupling are elucidated by analyzing the angular momentum dependence of the dipole polarizability and the hyperpolarizability, and comparing the fully and scalar relativistic calculated data. It is shown that the impact of the relativity and spin-orbit coupling are small for the dipole polarizability but become significant for the hyperpolarizability. Finally, the blackbody radiation shifts contributed by the dipole polarizability and hyperpolarizability, respectively, are evaluated for transitions of Al+ 3s 2 ¹S0 to 3s3p ³PJ with J=0,1,2 . [ABSTRACT FROM AUTHOR]

To reduce the friction coefficient between impregnated diamond bit and rock, experiments on addition of graphite to the matrix material of bit cutters were conducted. The cutters were made up of diamond contained working layers and binding layers. The friction and wear properties of cutters and binding layers were investigated using a pin-on-disc friction & wear tester with granite as tribopair. The results showed that with addition of graphite, the hardness and friction coefficient of binding layer decreased, but its wear resistance increased; compared to cutters without graphite, those cutters containing graphite had lower wear loss and friction coefficient and their sliding wear process was much steadier, but diamond protrusion was still normal.

A superhydrophobic membrane of MnO2nanotube arrays on which a water droplet can be immobilized by application of a small DC bias, despite a large contact angle, is reported. For a 3 μL water droplet, the measured adhesive force increases monotonically with increasing negative voltage, reaching a maximum of 130 μN at 22 V, 25 times the original value. It follows that the nearly spherical water droplet can be controllably pinned on the substrate, even if the substrate is turned upside down. Moreover, the electrically adjustable adhesion is strongly polarity‐dependent: only a five‐fold increase is found when a positive bias of 22 V is applied. This remarkable electrically‐controlled adhesive property is ascribed to the change in contact geometry between the water droplet and MnO2nanotube array, on which water droplets exhibit the different continuities of three‐phase contact line. As the modulation in this manner is in situ, fast, efficient and environmentally‐friendly, this kind of smart material with electrically adjustable adhesive properties has a wide variety of applications in biotechnology and in lab‐on‐chip devices.

For machining of hard and brittle materials, iron electrodeposit is a kind of matrix material with potential advantages for manufacture of diamond tools. Aiming at the problem of difficult codeposition of diamond in iron deposit, this paper adopts orthogonal design of experiment to study the effects of solution pH value, cathodic current density, alkylphenol polyoxyethylene (10) ether (OP-10) concentration and ammonium chloride concentration on codeposition of diamond, and then Fe-based diamond bits were fabricated and drilling tests in granite were carried out. The results show that pH value, cathodic current density, OP-10 concentration and ammonium chloride concentration all have statistically significant effect on codeposition of diamond in iron deposit, whose contributions to the variance of the weight of codeposited diamond are 37.45%, 32.05%, 13.13% and 12.38%, respectively. The result of drilling test indicates that Fe-based diamond bit can achieve much higher penetration rate than common Ni-based diamond bit.

In precision machining, the uniformity degree of abrasive distribution affects significantly the surface quality. To quantitatively evaluate the uniformity of abrasive distribution, in this paper digital image processing technology was employed to segment the working face images of impregnated diamond tools; mean crowding index was used to classify the pattern of abrasive distribution; fractal dimension determined by gyration radius method was applied to characterize the bulk uniformity of abrasive distribution on face plane; the coefficient of variation of Voronoi cell areas was adopted to describe the local distribution feature of abrasive grits. The results show that mean crowding index, fractal dimension and CV of Voronoi cell areas can characterize the uniformity of abrasive distribution from different points of view, and can be used to quantitatively evaluate the uniformity of abrasive distribution.

Formula uniform design method was adopted to study the performance of iron-based matrix with high content of phosphorus and boron. Two forms of regression models on matrix hardness and wear resistance and the optimum matrix formulae were obtained respectively by regression analysis and constrained nonlinear programming using MATLAB. Regression analyses indicate that matrix hardness was mainly affected by the factor of Ni, Co and Fe; matrix hardness and brittleness increased with the increment of P-Fe alloy, but decreased with the increase of 663-Cu. These results can be used as a rough guide for design of highly adaptive diamond bits for different rock formations. After the indoor experiments, diamond bit based on 3# matrix formula was made to perform field drilling tests. The results were that the penetration rate was 1.91m/h and the average diamond bit life was 67.37m.

To increase the manufacture efficiency of electroplated diamond tools, a nickel plating solution containing ammonium sulphate and sodium formate was investigated. The effects of concentration of ammonium sulphate, sodium formate and pH value on throwing power, covering power, ability to resist Cu2+ contamination and deposit microhardness were studied. Surface topography of deposits was also observed by SEM. Compared to watts bath, the plating solution studied is advantageous in terms of the performance of plating solution, deposit hardness and diamond bit behavior. Ammonium sulphate can refine deposit crystal grains and result in crystal form change.

Fe – Nd – P layers were prepared by electroless deposition. Discussed in this paper is the influence of the rare earth element Nd on the deposition rate, mixed potential, anti-corrosion performance, structure, and surface morphology of the deposit. The results show that the deposition rate increases with the addition of Nd and the increment can be as high as 30 %. The addition of Nd also improves the homogeneity of the deposit, eliminates pores, and reduces the particle size. Electroless Fe – P deposits incorporated with Nd also exhibit significantly improved anti-corrosion performance, especially in alkaline media.

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The ambiguities of the Seiberg-Witten map for gauge field coupled with fermionic matter are discussed. We find that only part of the ambiguities can be absorbed by gauge transformation and/or field redefinition and thus are negligible. The existence of matter field makes some other part of the ambiguities difficult to be absorbed by gauge transformation or field redefinition.