Diffusion dominated process for the crystal growth of a binary alloy

The pure diffusion process has been often used to study the crystal growth of a binary alloy in the microgravity environment. In the present paper, a geometric parameter, the ratio of the maximum deviation distance of curved solidification and melting interfaces from the plane to the radius of the crystal rod, was adopted as a small parameter, and the analytical solution was obtained based on the perturbation theory. The radial segregation of a diffusion dominated process was obtained for cases of arbitrary Peclet number in a region of finite extension with both a curved solidification interface and a curved melting interface. Two types of boundary conditions at the melting interface were analyzed. Some special cases such as infinite extension in the longitudinal direction and special range of Peclet number were reduced from the general solution and discussed in detail

Numerical Study on Flow Field and Temperature Distribution in Growth Process of 200 mm Czochralski Silicon Crystals

The melt flow and temperature distribution in a 200 mm silicon Czochralski furnace with a cusp magnetic field was modeled and simulated by using a finite-volume based FLUTRAPP ( Fluid Flow and Transport Phenomena Program) code. The melt flow in the crucible was focused, which is a result of the competition of buoyancy, the centrifugal forces caused by the rotations of the crucible and crystal, the thermocapillary force on the free surfaces and the Lorentz force induced by the cusp magnetic field. The zonal method for radiative heat transfer was used in the growth chamber, which was confined by the crystal surface, melt surface, crucible, heat shield, and pull chamber. It was found that the cusp magnetic field could strength the dominant counter-rotating swirling flow cell in the crucible and reduce the flow oscillation and the pulling-rate fluctuation. The fluctuation of dopant and oxygen concentration in the growing crystal could thus be smoothed

Anti-diabetic effects of emodin involved in the activation of PPAR gamma on high-fat diet-fed and low dose of streptozotocin-induced diabetic mice

Rheum palmatum unit has been widely applied in the clinical treatment of diabetes mellitus It has been found that emodin as the major bioactive component of R palmatum L exhibits the competency to activate peroxisomal proliferator-activated receptor-gamma (PPAR gamma) in vitro So the aim of this study was to evaluate the anti-diabetic effects of emodin through the activation of PPAR gamma on high-fat diet-fed and low dose of streptozotocin (STZ)-induced diabetic mice The diabetic mice were intraperitoneally injected with emodin for three weeks No changes of food consumption and the body weight in emodin-treated mice were monitored daily during the entire experiment At the end of experiment. the levels of blood glucose, triglyceride and total cholesterol in serum were significantly decreased after emodin treatment. However, serum high-density lipoprotein cholesterol (HDLc) concentration was significantly elevated The glucose tolerance and insulin sensitivity in emodin-treated group were significantly improved Furthermore, the results of quantitative RT-PCR analysis showed that emodin significantly elevated the mRNA expression level of PPAR gamma and regulated the mRNA expressions of LPL. FAT/CD36, resistin and FABPs (ap2) in liver and adipocyte tissues. No effects on the mRNA expressions of PPAR alpha and PPAR alpha-target genes were observed Taken together, the results suggested that the activation of PPAR gamma and the modulation of metabolism-related genes were likely involved in the anti-diabetic effects of emodin (C) 2009 Elsevier B V All rights reserve

Infection of Myxobolus turpisrotundus sp n. in allogynogenetic gibel carp, Carassius auratus gibelio (Bloch), with revision of Myxobolus rotundus (s. l.) Nemeczek reported from C-auratus auratus (L.)

Infection of a Myxobolus species, previously identified as Myxobolus rotundus, was detected in 182 of 7892 (2.31%) allogynogenetic gibel carp, Carassius auratus gibelio, in a closed pond culture system in China. Morphological and molecular data showed that this myxosporean is a different species from M. rotundus parasitizing Abramis brama in Europe and is thus designated as a new species, Myxobolus turpisrotundus. M. rotundus (s.l.) ex C. auratusauratus is a synonym of M. turpisrotundus. Plasmodia of M. turpisrotundus develop in the subepidermal tissues of the body surface resulting in an unaesthetic appearance and causing severe economic losses. Prevalence of infection with the myxosporean plasmodia varied seasonally, increasing in winter and decreasing in spring. Prevalence was positively correlated to host size, but no host sex-specificity was found. No infection was observed in other fish species (grass carp, bighead carp and yellow catfish) reared in the same pond, suggesting that the parasite has a relatively strict host specificity. Plasmodia grew gradually as the parasite developed, and reached up to a maximum 5.6 mm in diameter. Plasmodia ruptured naturally to release the mature spores and host fish completely recovered with no mortality. Release of spores and regeneration of lesions were not correlated with water temperature. Histology showed that plasmodia developed sub-epidermally, and that the wall of the plasmodia was composed of a multiple complex structure, including layers of fibroblasts, a collagenous membrane, melanophores and a layer of cup-like cells of unknown derivation and function. The cup-like cells are in direct contact with pre-sporogonic stages located in the peripheral parts of the large plasmodia. No severe host inflammatory response was seen

Spatial Distribution of the Attentional Blink

In the present study subjects viewed streams of rapid serially presented characters and searched for a target digit. After presentation of the target digit, a second target consisting of an orientation singleton (Experiment 1) or a second digit (Experiment 2) was presented at one of several distances from the first target. The attentional blink (AB) impaired performance on the second target with the effect being strongest at distances somewhat removed from the first target location. These results are consistent with lateral inhibition theory and help to resolve some fundamental questions about the spatial distribution of the AB

Comparative study of nitrogenase activity in different types of biological soil crusts in the Gurbantunggut Desert, Northwestern China

Biological soil crusts cover large areas of the Gurbantunggut Desert in northwestern China where they make a significant contribution to soil stability and fertility. The aim of this study was to quantify the potential nitrogen-fixing activity (NA) of different types of biological soil crusts in the Gurbantunggut Desert. The results suggest that NA (nmol C2H4 m(-2) h(-1)) for each type of crusts was highly variable. Seasonal variation was also important, with all three types of crusts responding in a similar way to changes in environmental conditions. From March to May, NA was relatively low for all crust types. During this season, NA was 2.26 x 10(3) for cyanobacterial crust followed by lichen crust (6.54 x 10(2)) and moss crust (6.38 x 10(2)). From June to October, all crust types reached their highest level of NA, especially lichen crust and moss crust (p < 0.01). The NA of cyanobacterial crust (9.81 x 10(3)) was higher than that of lichen crust (9.06 x 10(3)) and moss crust (2.03 x 10(3)). From November to February, when temperatures were consistently low (<0 degrees C), NA was at its lowest level, especially in cyanobacterial crust (4.18 x 10(2)) and moss crust (5.43 x 10(2)) (P < 0.01). Our results indicate that species composition is critical when estimating N inputs in desert ecosystems. fit addition, all three types of crusts generally responded in a similar way to environmental conditions. The presence of N fixation activity in all crusts may contribute to the maintenance of fertility in sparsely vegetated areas and provide surrounding vascular plant with fixed nitrogen. (C) 2009 Elsevier Ltd. All rights reserved

Chromosomal rearrangements and karyotype evolution in carnivores revealed by chromosome painting

Chromosomal evolution in carnivores has been revisited extensively using cross-species chromosome painting. Painting probes derived from flow-sorted chromosomes of the domestic dog, which has one of the most rearranged karyotypes in mammals and the highest dipoid number (2n=78) in carnivores, are a powerful tool in detecting both evolutionary intra- and inter-chromosomal rearrangements. However, only a few comparative maps have been established between dog and other non-Canidae species. Here, we extended cross-species painting with dog probes to seven more species representing six carnivore families: Eurasian lynx (Lynx lynx), the stone marten (Martes foina), the small Indian civet (Viverricula indica), the Asian palm civet (Paradoxurus hermaphrodites), Javan mongoose (Hepestes javanicas), the raccoon (Procyon lotor) and the giant panda (Ailuropoda melanoleuca). The numbers and positions of intra-chromosomal rearrangements were found to differ among these carnivore species. A comparative map between human and stone marten, and a map among the Yangtze finless porpoise (Neophocaena phocaenoides asiaeorientalis), stone marten and human were also established to facilitate outgroup comparison and to integrate comparative maps between stone marten and other carnivores with such maps between human and other species. These comparative maps give further insight into genome evolution and karyotype phylogenetic relationships among carnivores, and will facilitate the transfer of gene mapping data from human, domestic dog and cat to other species

Spreading area and shape regulate apoptosis and differentiation of osteoblasts

The in vivo observations have indicated that at the remodeling sites of bone, the spreading area or shape of preosteoblasts is confined by the mineralized matrix. But it remains unknown whether this spreading confinement regulates the differentiation or apoptosis of osteoblasts. In the present study, osteoblast-like cells (MC3T3-E1) were seeded on micropatterned islands with different area and shape. The expression of three osteogenic differentiation markers was measured by immunofluorescence staining and apoptotic cells were detected using a terminal deoxyribonucleotidyl transferase-mediated dUTP nick end labelling assay kit. The membrane fluorescence staining results showed that the actual spreading area of micropatterned osteoblasts coincided with the designed value. When the area of a micropatterned cell was confined as 314 or 615 mu m(2), which was lower than that of freely spreading osteoblasts, the circular shape promoted the expression of osteogenic differentiation markers and the percentage of apoptotic osteoblasts compared with the branched shape. This shape-regulated differentiation and apoptosis of osteoblasts with confined spreading area were abolished when actin polymerization was inhibited by cytochalasin D. The present study gives an insight into the roles of spreading morphology on osteoblastic differentiation and apoptosis

Differentiation of Soil Conditions over Low Relief Areas Using Feedback Dynamic Patterns

In many areas, such as plains and gently undulating terrain, easy-to-measure soil-forming factors such as landform and vegetation do not co-vary with soil conditions across space to the level that they can be effectively used in digital soil mapping. A challenging problem is how to develop a new environmental variable that co-varies with soil spatial variation under these situations. This study examined the idea that change patterns (dynamic feedback patterns) of the land surface, such as those captured daily by remote sensing images during a short period (6-7 d) after a major rain event, can be used to differentiate soil types. To examine this idea, we selected two study areas with different climates: one in northeastern China and the other in northwestern China. Images from the Moderate Resolution Imaging Spectroradiometer (MODIS) were used to capture land surface feedback. To measure feedback dynamics, we used spectral information divergence (SID). Results of an independent-samples t-test showed that there was a significant difference in SID values between pixel pairs of the same soil subgroup and those of different subgroups. This indicated that areas with different soil types (subgroup level) exhibited significantly different dynamic feedback patterns, and areas within the same soil type have similar dynamic feedback patterns. It was also found that the more similar the soil types, the more similar the feedback patterns. These findings could lead to the development of a new environmental covariate that could be used to improve the accuracy of soil snapping in low-relief areas

Do Minkowski averages get progressively more convex?

Abstract Let us define, for a compact set A ⊂ R n , the Minkowski averages of A: We study the monotonicity of the convergence of A(k) towards the convex hull of A, when considering the Hausdorff distance, the volume deficit and a non-convexity index of Schneider as measures of convergence. For the volume deficit, we show that monotonicity fails in general, thus disproving a conjecture of Bobkov, Madiman and Wang. For Schneider's non-convexity index, we prove that a strong form of monotonicity holds, and for the Hausdorff distance, we establish that the sequence is eventually nonincreasing. Résumé Les moyennes de Minkowski deviennent-elles progressivement plus convexes ? Pour tout ensemble compact A ⊂ R n , définissons ses moyennes de Minkowski par Nousétudions la monotonie de la convergence de A(k) vers l'enveloppe convexe de A, mesurée par la distance de Hausdorff, le déficit volumique et par l'indice de non-convexité de Schneider. Pour le déficit volumique, nous démontrons que la propriété de monotonie n'est pas satisfaite en général, réfutant ainsi une conjecture de Bobkov, Madiman et Wang. Pour l'index de non-convexité de Schneider, nous montrons une propriété renforcée de monotonie tandis que pour la distance de Hausdorff, nousétablissons que la suite est strictement décroissanteà partir d'un certain rang. Version française abrégée L'objectif de cette note est d'annoncer et de démontrer une partie des résultats obtenus dans [3] qui portent sur l'étude de la monotonie de la suite (A(k)) k≥1 définie en (1), mesuréeà travers différentes mesures de non-convexité. Intuitivement, les ensembles A(k) deviennent de plus en plus convexes au fur età mesure que k croît. Cette intuition est précisée dans désigne le déficit volumique d'un ensemble compact de R n . Ici, Vol n représente la mesure de Lebesgue dans R n et conv(A) désigne l'enveloppe convexe de A. Nous réfutons cette conjecture en exhibant un contre-exemple explicite en dimension supérieure ouégaleà 12. Le contre-exemple est la réunion de deux ensembles convexes inclus dans des sous-espaces de dimension (presque) moitié de l'espace ambiant (voir De manière analogueà la conjecture de Bobkov-Madiman-Wang, nousétudions la monotonie de la suite (c(A(k))) k≥1 , où c est l'index de non-convexité de Schneider [6] défini par c(A) := inf{λ ≥ 0 : A + λ conv(A) est convexe}. Contrairement au déficit volumique, la suite (c(A(k))) est strictement décroissante,à moins que A(k) soit déjà convexe. Plus précisément nous montrons que pour tout ensemble compact A de R n et tout k ∈ N