Bubble evolution in the titanium alloy melt under vertical centrifugal field

The bubble evolution in the liquid titanium melt under vertical centrifugal field has been studied by the hydraulic experiment simulation. The bubble migration process in the simple and complex cavities, the bubble morphology, bubble dimensional size diversification under different mould rotational speed has been investigated. The results show that the mould wall has a blocking effect on the bubble migration. The bubble migration in the simple cavity deviates from the line between the bubble initial position and the rotation shaft of the casting mould. Also, the bubbles in the complex cavity gather, re-nucleate and form new big ones for the blocking effect of the complex geometry shape on the radial movement of the bubble. The shape of bubbles in both the simple and complex cavity during the migration process is not a perfect sphere, but an elliptical shape. The critical size of bubble released from the bubble generation chamber decreases with the increment of the mould rotational speed. The diameter of the gas bubbles in the simple cavity during the migration process become bigger and bigger for the pressure difference at different positions of the cavity in the vertical centrifugal field

Atypical sliding and Moire ferroelectricity in pure multilayer graphene

Most non-ferroelectric two-dimensional materials can be endowed with so-called sliding ferroelectricity via non-equivalent homo-bilayer stacking, which is not applicable to mono-element systems like pure graphene bilayer with inversion symmetry at any sliding vector. Herein we show first-principles evidence that multilayer graphene with N>3 can all be ferroelectric, where the polarizations of polar states stem from the symmetry breaking in stacking configurations of across-layer instead of adjacent-layer, which are electrically switchable via interlayer sliding. The non-polar states can also be electrically driven to polar states via sliding, all nearly degenerate in energy, and more diverse states with distinct polarizations will emerge in more layers. In contrast to the ferroelectric Moire domains with opposite polarization directions in twisted bilayers reported previously, the Moire pattern in some multilayer graphene systems (e.g., twisted monolayer-trilayer graphene) possess nonzero net polarizations with domains of the same direction separated by non-polar regions, which can be electrically reversed upon interlayer sliding. The distinct Moire bands of two polar states should facilitate electrical detection of such sliding Moire ferroelectricity during switching

Kinetic energy driven superconductivity in doped cuprates

Within the t-J model, the mechanism of superconductivity in doped cuprates is studied based on the partial charge-spin separation fermion-spin theory. It is shown that dressed holons interact occurring directly through the kinetic energy by exchanging dressed spinon excitations, leading to a net attractive force between dressed holons, then the electron Cooper pairs originating from the dressed holon pairing state are due to the charge-spin recombination, and their condensation reveals the superconducting ground-state. The electron superconducting transition temperature is determined by the dressed holon pair transition temperature, and is proportional to the concentration of doped holes in the underdoped regime. With the common form of the electron Cooper pair, we also show that there is a coexistence of the electron Cooper pair and antiferromagnetic short-range correlation, and hence the antiferromagnetic short-range fluctuation can persist into the superconducting state. Our results are qualitatively consistent with experiments.Comment: 6 pages, Revtex, two figures are included, corrected typo

G-CSF mobilized PBMCs contribute to the liver function of cirrhotic rats

On the basis of the recently recognized potential of bone marrow stem cells to give rise to hepatocytes, we here investigated the role of G-CSF priming PBMCs played in the liver of cirrhotic rats. The animal model of liver cirrhosis was induced by injecting CCl4 in SD rats, and G-CSF was administered in hematopoietic stem cell mobilization doses. After the liver cirrhosis model was established, the female cirrhotic rats were divided into two groups. Group I only received G-CSF mobilization, group II received G-CSF mobilized PBMCs transplanted from the male cirrhotic rats. PKH26 staining and sex-determining region for the Y-chromosome gene were used to trace the transplanted cells. Liver function related factors were assayed under the animal automatic biochemistry analyzer, and the liver pathological changes were evaluated by HE staining. The comparative liver functions of the two groups were investigated by analysis of two sample t-tests. A P value of <0.05 was considered as significant in all analyses. Our results showed that the transplanted PBMCs could locate in the livers of the female rats. In addition, compared with the group I, rats in group II displayed significant liver improvement in serum ALB, ALT, AST and TBIL (p<0.05). However, the semi-quantitative classification of the liver pathological changes in both groups did not indicate a significant difference (p>0.05). The results indicated that mobilized PBMC transplant could contribute to liver function in cirrhotic livers, which might be an alternative therapy for liver cirrhosis

呼称語の変容

呼称語は,対人関係用語とも言われているように,話し手と聞き手の位置関係や話の場を最も鋭敏に反映する言語分野であり,相手をいかに呼ぶかによって,その関係は近くもなれば遠くもなる。人間関係を和やかにさせるために,どんな社会においても,相手をどう呼ぶかについて,心配りをしている。近年,中国社会の変動は激しく,人々の価値観などにも目覚しい変化が起きている。言語は社会的事実であり,社会の鏡とも言われている。このような激変している時代において,呼称語の使用法にどのような変化があるかを調べるために,まず,中国の大学生の間における,中国語の呼称語の使い方について考察してみた。中国北京第二外国語学院日本語学部の学生100人を対象に,1994年1月と1999年1月の二回にわたって,呼称語についてアンケート調査を行った。その調査結果を見ると,いくつかの変化が見られたので,本文ではその変容を考えてみたい

Giant vortex and Skyrmion in a rotating two-species Bose-Einstein condensate

Numerical simulations are performed for a rotating two-species Bose condensate confined by a harmonic potential. The particle numbers of each species are unequal. When the rotational speed exceeds a critical value, the majority species reside in the center of the potential while the minority species is pushed out to the outskirts, forming a giant vortex hole to contain the majority species. A novel annular Skyrmion forms at the interface of the two species.Comment: 5 pages, 5 figure