Influence of micron WC addition on the microstructure and mechanical properties of ultrafine WC–Co cemented carbides at the elevated temperature

In this paper, the influence of micron-grained WC additions with the different grain sizes on the microstructure and hardness of ultrafine WC–Co cemented carbides at the elevated temperature were investigated by the scanning electron microscope and mechanical properties test. The Vickers hardness and transverse rupture strength of hardmetals were measured at temperatures ranging from room temperature to 800 °C. The results show that the addition of micron-sized WC particles can lead to the increase of fracture toughness and slow the decreasing of hardness at the elevated temperature.Досліджено вплив добавок WC з зернами різних мікронних розмірів на мікроструктуру і твердість надтвердого WC–Co-сплаву при підвищеній температурі за допомогою скануючого електронного мікроскопу і проведено випробування його механічних властивостей. Твердість за Віккерсом і поперечну міцність на розрив твердих металів вимірювали у діапазоні від кімнатної температури до 800 °С. Результати показали, що добавка WС-частинок мікронних розмірів може призвести до збільшення тріщиностійкості і уповільнити зменшення твердості при підвищеній температурі.Исследовано влияние добавок WС с зернами различных микронных размеров на микроструктуру и твердость сверхтвердого WC–Co-сплава при повышенной температуре с помощью сканирующего электронного микроскопа и проведено испытание его механических свойств. Твердость по Виккерсу и поперечную прочность на разрыв твердых металлов измеряли в диапазоне от комнатной температуры до 800 °C. Результаты показали, что добавка WС-частиц микронных размеров может привести к увеличению трещиностойкости и замедлить уменьшение твердости при повышенной температуре

Efficient Agrobacterium tumefaciens -mediated transformation of Malus zumi (Matsumura) Rehd using leaf explant regeneration system

Malus zumi is known as an excellent dwarfing apple rootstock occurring in natural or arid/semiarid soil or salina. Gene manipulation of M. zumi through transgenic technology can modify plant feature for further improvement fruit tree production by grafting the scion on a transgenic rootstock. Here, we report the establishment of an efficient, in vitro, shoot regeneration system and Agrobacterium tumefaciens - mediated transformation from the leaf explants for Malus zumi (Matsumura) Rehd. Leaf explants were infected with Agrobacterium strains containing nptII and gus gene. The highest frequency of shoot regeneration was obtained on MS medium containing 500 mg l-1 Lactalbumin hydrolysate, 30 g l-1 fructose, supplemented with 3.0 mg l-1 BA, 0.2 mg l-1 NAA.Using fructose instead of sucrose significantly increases the shoot regeneration and decreases vitrification. This regeneration procedure was incorporated into an Agrobacterium-mediated transformation procedure in M. zumi. Kanamycin was an efficient selective agent for selection. Pre-selection (5 days after co-cultivation) improved the transformation efficiency. The emergence of expected bands by PCR analysis and Southern blot in transgenic plantlets confirmed the transformation of foreign DNA into plant genome

In-plane magnetic anisotropy of bcc Co on GaAs 001

Y. Z. Wu, H. F. Ding, C. Jing, D. Wu, G. L. Liu, V. Gordon (currently with UT Austin), G. S. Dong, and X. F. Jin are with Fudan T. D. Lee Physics Laboratory and Surface Physics Laboratory, Fudan University, Shanghai 200433, China -- S. Zhu and K. Sun are with the Beijing Laboratory of Electron Microscopy, Chinese Academy of Science, and Department of Material Engineering, Dalian University of Technology, Dalian, ChinaEpitaxial growth of Co on GaAs(001) and its in-plane magnetic anisotropy are studied using reflection high-energy electron diffraction, a high-resolution transmission electron microscope, and the magneto-optical Kerr effect. In the initial and final stages of growth, Co exists in single-crystalline body-centered-cubic (bcc) and hexagonal-closed-packed (hcp) phases, respectively, while in the middle stage the coexistence of the bcc and hcp structures is observed. For the bcc Co thin films on GaAs(001), a fourfold in-plane magnetic anisotropy with easy axes along the directions is realized and discussed.Chemistr

Effects of different probiotics on the gut microbiome and metabolites in the serum and caecum of weaning piglets

The objective of the study was to determine the effects of antibiotics, yeast culture (YC), and Lactobacillus culture (LC) on the gut microbiome and metabolites in the serum and caecum of weaning piglets. Twenty-four weaning piglets were divided into four treatment groups: control, antibiotic (1% chlortetracycline), 1.8% yeast culture (YC), and 1.6% Lactobacillus culture groups (LC). Each group had six replicated pens with one pig per pen. Feed and water were available ad libitum. Dietary supplementation with antibiotics, YC and LC increased the abundance of phylum, Firmicutes, and decreased the abundance of phylum, Proteobacteria. Beneficial bacteria such as Lactobacillus and Megasphaera in YC and LC groups increased, whereas the proportion of Shigella was decreased. Genera Alloprevotella and Lachnospira were biomarkers in the control and antibiotic groups, respectively. Phylum, Bacteroidetes, and genus, Collinsella, were biomarkers in the YC group, and Mitsuokella, Anaerotruncus, Syntrophococcus and Sharpea were biomarkers in the LC group. Dietary supplementation with different probiotics changed the serum and caecum metabolite profiles too. Antibiotic supplementation increased the levels of D-mannose, D-glucose, and hexadecanoic acid in the serum, and the levels of myo-inositol, D-mannose and benzenepropanoic acid in the caecum. LC increased the concentrations of D-mannose, cis-9-hexadecenoic acid and heptadecanoic acid in caecum compared with the control group. YC and LC supplementation in the weaning diet could improve the abundance of beneficial bacteria by changing the concentrations of some metabolites in the serum and caecum. Therefore, dietary supplementation with YC or LC could be used as additives instead of antibiotics in weaning piglets.Keywords: antibiotic; lactobacillus culture; yeast culture; high-throughput sequencing; gas chromatography mass spectrometr

Partial wave analysis of J/\psi \to \gamma \phi \phi

Using $5.8 \times 10^7 J/\psi$ events collected in the BESII detector, the radiative decay $J/\psi \to \gamma \phi \phi \to \gamma K^+ K^- K^0_S K^0_L$ is studied. The $\phi\phi$ invariant mass distribution exhibits a near-threshold enhancement that peaks around 2.24 GeV/$c^{2}$. A partial wave analysis shows that the structure is dominated by a $0^{-+}$ state ($\eta(2225)$) with a mass of $2.24^{+0.03}_{-0.02}{}^{+0.03}_{-0.02}$ GeV/$c^{2}$ and a width of $0.19 \pm 0.03^{+0.06}_{-0.04}$ GeV/$c^{2}$. The product branching fraction is: $Br(J/\psi \to \gamma \eta(2225))\cdot Br(\eta(2225)\to \phi\phi) = (4.4 \pm 0.4 \pm 0.8)\times 10^{-4}$.Comment: 11 pages, 4 figures. corrected proof for journa

Measurements of the observed cross sections for e+e−→e^+e^-\to exclusive light hadrons containing π0π0\pi^0\pi^0 at s=3.773\sqrt s= 3.773, 3.650 and 3.6648 GeV

By analyzing the data sets of 17.3, 6.5 and 1.0 pb$^{-1}$ taken, respectively, at $\sqrt s= 3.773$, 3.650 and 3.6648 GeV with the BES-II detector at the BEPC collider, we measure the observed cross sections for $e^+e^-\to \pi^+\pi^-\pi^0\pi^0$, $K^+K^-\pi^0\pi^0$, $2(\pi^+\pi^-\pi^0)$, $K^+K^-\pi^+\pi^-\pi^0\pi^0$ and $3(\pi^+\pi^-)\pi^0\pi^0$ at the three energy points. Based on these cross sections we set the upper limits on the observed cross sections and the branching fractions for $\psi(3770)$ decay into these final states at 90% C.L..Comment: 7 pages, 2 figure

Direct Measurements of Absolute Branching Fractions for D0 and D+ Inclusive Semimuonic Decays

By analyzing about 33 $\rm pb^{-1}$ data sample collected at and around 3.773 GeV with the BES-II detector at the BEPC collider, we directly measure the branching fractions for the neutral and charged $D$ inclusive semimuonic decays to be $BF(D^0 \to \mu^+ X) =(6.8\pm 1.5\pm 0.7)$ and $BF(D^+ \to \mu^+ X) =(17.6 \pm 2.7 \pm 1.8)$, and determine the ratio of the two branching fractions to be $\frac{BF(D^+ \to \mu^+ X)}{BF(D^0 \to \mu^+ X)}=2.59\pm 0.70 \pm 0.25$