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The hot-tearing susceptibility (HTS) of Mg-6Zn-xGd (x=0.5, 1, 2, 3, 4, 6) alloys was evaluated using a constrained rod casting (CRC) method. The results show that the HTS curve follows a typical “Λ” shape with the increase of Gd content. The Mg-6Zn-2Gd alloy has the highest while Mg-6Zn-6Gd alloy has the lowest HTS value. The hot-tearing behavior characteristics of Mg-6Zn-xGd alloys were further studied through a multifunctional hot-tearing test device. According to the dendrite contact point inferred from the stress curve, the Clyne-Davies criterion was modified and found to be accurate in predicting the HTS of Mg-6Zn-xGd alloys. Microstructure observation reveals that the grain size and the volume of eutectic liquid are the two key factors affecting HTS of Mg-6Zn-xGd alloys. The large grain with columnar structure can easily promote initiation and propagation of hot-tearing due to the poor feeding and coordinating deformation capability, which have a harmful effect on HTS. A higher volume fraction of eutectic phase can refill the cracking and provide continuous feeding channels by dendrite bridge and thicker liquid film, thus increase the hot-tearing resistance.

In order to reduce CO2 emission and energy consumption, more recycled secondary materials have to be used in foundry industry, especially for Al-Si-Mg based alloys for semi-solid processing. In this paper, Al-Si-Mg based alloys with the addition of recycled secondary materials up to 30 % (10, 20, 30 %, respectively) have been produced by semi-solid processing. The solidification microstructure was investigated using optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Furthermore, computed tomography (CT) was also used to elucidate the size, size distribution, number density, volume fraction of porosities. It was found that with the addition of the recycled secondary materials up to 30 %, there is no significant effect on the solidification microstructure in terms of the grain size and the shape factor of primary α-Al and the second α-Al. More importantly, the morphology of eutectic Si can be well modified and that of the Fe-containing phase (π-AlSiMgFe) can be tailored. Furthermore, with increasing recycled secondary materials, at least another two important issues should also be highlighted. Firstly, more TiB2 particles were observed, which can be due to the addition of Al-Ti-B grain refiners for the grain refinement of recycled secondary materials. Secondly, a significant interaction between Sr and P was also observed in the recycled secondary materials. The present investigation clearly demonstrates that Al-Si-Mg based alloys with the addition of recycled secondary materials at least up to 30% can be used for semi-solid processing, which may facilitate better sustainability.

Microstructures and mechanical properties of directionally solidified Mg-xGd (5.21, 7.96 and 9.58 wt.%) alloys were investigated at a wide range of growth rates (V = 10-200 μm/s) under the constant temperature gradient (G = 30 K/mm). The results showed that when the growth rate was 10 μm/s, different interface morphologies were observed in three tested alloys: cellular morphology for Mg-5.21Gd alloy, a mixed morphology of cellular structure and dendritic structure for Mg-7.96Gd alloy and dendrite morphology for Mg-9.58Gd alloy, respectively. Upon further increasing the growth rate, only dendrite morphology was exhibited in all experimental alloys. The microstructural parameters (λ1, λ2) decreased with increasing the growth rate for all the experimental alloy, and the measured λ1 and λ2 values were in good agreement with Trivedi model and Kattamis-Flemings model, respectively. Vickers hardness and the ultimate tensile strength increased with the increase of the growth rate and Gd content, while the elongation decreased gradually. Furthermore, the relationships between the hardness, ultimate tensile strength, the growth rate and the microstructural parameters were discussed and compared with the previous experimental results.

An extended continuum mixture model for macrosegregation is applied to predicting Cu and Mg segregation in large-size ingot of 2024 aluminum alloy during direct chill casting (DC). A microsegregation model using the approximate phase diagram data was coupled with macroscopic transport equations for macrosegregation profiles. Then, the impacts of transport mechanisms on the formation of macrosegregation were discussed. It is found that copper and magnesium have a similar segregation configuration from the billet center to surface. Negative segregation is observed in the centerline and subsurface, whereas positive segregation is obtained in the surface and somewhat underestimated positive segregation in the middle radius. Further, the discrepancy between the predicted and experimental results was discussed in detail. The results show that the magnesium to some extent alleviates the copper segregation in ternary alloy, compared with that in binary alloy. The predicted results show good agreement with measured experimental data obtained from literatures.

Directional solidification of Mg–2.35Gd (mass fraction, %) magnesium alloy was carried out to investigate the effects of the solidification parameters (growth rate vand temperature gradient G) on microstructure and room temperature mechanical properties under the controlled solidification conditions. The specimens were solidified under steady state conditions with different temperature gradients (G=20, 25 and 30 K/mm) in a wide range of growth rates (v=10–200 μm/s) by using a Bridgman-type directional solidification furnace with liquid metal cooling (LMC) technology. The cellular microstructures are observed. The cellular spacing λdecreases with increasing vfor constant Gor with increasing Gfor constant v. By using a linear regression analysis the relationships can be expressed as λ=136.216v−0.2440(G=30 K/mm) and λ=626.5630G−0.5625(v=10 μm/s), which are in a good agreement with Trivedi model. An improved tensile strength and a corresponding decreased elongation are achieved in the directionally solidified experimental alloy with increasing growth rate and tempertaure gradient. Furthermore, the directionally solidified experimental alloy exhibits higher room temperature tensile strength than the non-directionally solidified alloy.

The influence of filling parameters including pouring temperature, filling speed, boost pressure and synchronous pressure on the fatigue of A357 alloy produced by counter pressure plaster casting was studied. The Taguchi method was used to investigate the relationship between the fatigue performance and filling parameters. The results show that filling speed is the most significant factor among the four parameters. Synchronous pressures is less influential on the fatigue life when the value of synchronous pressure is from 400 kPa to 600 kPa.

Pressurization control system plays an important role in the process control at the stages of riser-tube filling, mold-filling, pressure-increasing and pressure maintaining in counter-gravity casting. Casting quality is affected by the precision of pressurization control system to a great extent. Input and output scaling factors of conventional fuzzy controller are static, which is hard to ensure a suitable state for various counter-gravity casting equipments. A new fuzzy controller with self-tuning scaling factors has been developed in our laboratory, which will be described in this paper. Input and output scaling factors of fuzzy controller are tuned by different error ranges. When the differential pressure error is large, output scaling factor is increased to speed up dynamic response. At the same time, input scaling factors are also increased in order to reduce steady state error. Compared to fuzzy controller and conventional PID controller, fuzzy-PID controller with self-tuning scaling factors has more steady-state precision and excellent robustness. Experimental results show that at riser-tube filling stage and mold-filling stage the gas flow is stable, and the tracking property of pressurization control system is very satisfactory.

The elastic and thermodynamic properties of CdTe are studied under a pressure up to 8GPa and at a temperature range of 0~900K, by density functional theory as well as quasi-harmonic Debye model. The calculated bulk modulus B and its derivative B' are consistent with the values fitted according to Debye model, which confirms the applicability of Debye model to CdTe. Heat capacity Cv , Grüneisen parameter and thermal expansion coefficient decrease with pressure, but increase with temperature. It is an opposite case for Debye temperature . The results may be instructive for CdTe to be applied in extreme conditions.

Different thickness of CdZnTe films were deposited onto glass substrates by RF magnetron sputtering from Cd0.9Zn0.1Te crystals target. Their structural characteristics were studied by X-ray diffraction (XRD). The XRD experiments showed that the films are polycrystalline and have a zinc-blende (cubic) structure. The crystallite size and micro-strain were calculated. It is observed that the crystallite size increases and micro-strain decreases with the film thickness. The optical measurements showed that the average transmittance of all the samples have is less than 50% in the visible range. The possible optical transition in these films is found to be allowed direct transition with energy gap increase from 1.53 to 1.75 eV. For the electrical properties, the sheet resistivity decreased from 2.582×108 to3.069×107 Ohm/sq when the thickness increased from 307 to 823 nm; while the carrier concentration seems to be less affected by the film thickness. This behaviour in electrical properties was explained by the crystallinity and the grain size evolution.

Mast cells play a pivotal role in IgE-mediated allergic responses. Development of specific inhibitors against FcεRI-associated proximal signaling molecules in mast cells may represent a promising therapeutic strategy for allergic diseases. We examined whether a novel synthetic compound, 3-butyl-1-chloro-8-(2-methoxycarbonyl)phenyl-5H-imidazo[1,5-b]isoquinolin-10-one (U63A05), could suppress antigen-stimulated degranulation and cytokine secretion in mast cells and IgE-mediated passive cutaneous anaphylaxis (PCA) in mice. U63A05 reversibly and dose-dependently inhibited degranulation of rat basophilic leukemia (RBL)-2H3 mast cells and bone marrow–derived mast cells (BMMCs) stimulated by antigen (IC50values for RBL-2H3 and BMMCs were 4.1 and 4.8 μM, respectively). The secretion of inflammatory cytokines was also suppressed in antigen-stimulated mast cells. However, degranulation by thapsigargin, a typical calcium inducer, was not inhibited by U63A05. U63A05 exerts its inhibitory effect, to the same extent as in degranulation, on the activating phosphorylation of Syk and downstream signaling molecules, including LAT and SLP-76. Further downstream, the activating phosphorylations of Akt, Erk1/2, p38, and JNK were also inhibited. Finally, antigen-stimulated PCA was dose-dependently suppressed in mice (ED50, 26.3 mg/kg). Taken together, the results suggest that U63A05 suppresses the activation of mast cells and the mast cell–mediated allergic response through the inhibition of Syk activation in mast cells.

A new composition sand-casting magnesium alloy, Mg-6Zn-2Gd-0.6Zr, was developed. It was found that the room temperature mechanical properties of the alloy were superior: b=270MPa, 0.2=175MPa, =8%. Meanwhile, the elevated-temperature strength and creep resistance were significantly improved, comparing with Mg-5Zn-0.6Zr (ZK51) commercial magnesium alloy. The as-cast microstructure of the alloy was mainly consisted of (Mg) matrix, (+Mg3Gd2Zn3+Mg3Gd) eutectic phase, which was distributed along the (Mg) grain boundary with coarse netted shape. After solid-solution treatment and subsequently aging treatment for the alloy, the secondary phases re-precipitated as fine discontinues semi-netted or short rod-like precipitations, also including some fine spherical precipitations in the  matrix, which were responsible for the properties improvement of the alloy.

A counter-gravity casting equipment (CGCE) has been developed, which is specially designed for the production of large-size thin-walled high-quality aluminum alloy parts with resin sand molds. In this equipment, molten metal will be pushed upward counter-gravity into the mold at predetermined rate by compressed air, and solidified at an increased pressure. The equipment uses assembled valve system developed ourselves, and has sensitive pressure-adjusting property. All of the casting parameters, including filling rate, pressure-exerting sequence, pressure hold time etc., can be closely controlled by a self-designed computer program. Up to 2 ton casting can be produced with the equipment. Compared to the castings produced under conventional gravity conditions, the castings under counter-gravity condition have generally high soundness, higher tensile strengths and ductility. The pinhole defects are also degraded obviously. The equipment and the technology have been widely adopted by several users in China for the production of large-size thin-walled aluminum alloy castings with high property requirements.

We investigated whether oral administration of curcumin suppressed type II collagen–induced arthritis (CIA) in mice and its effect and mechanism on matrix metalloproteinase (MMP)-1 and MMP-3 production in CIA mice, RA fibroblast-like synoviocytes (FLS), and chondrocytes. CIA in mice was suppressed by oral administration of curcumin in a dose-dependent manner. Macroscopic observations were confirmed by histological examinations. Histological changes including infiltration of immune cells, synovial hyperplasia, cartilage destruction, and bone erosion in the hind paw sections were extensively suppressed by curcumin. The histological scores were consistent with clinical arthritis indexes. Production of MMP-1 and MMP-3 were inhibited by curcumin in CIA hind paw sections and tumor necrosis factor (TNF)-α–stimulated FLS and chondrocytes in a dose-dependent manner. As for the mechanism, curcumin inhibited activating phosphorylation of protein kinase Cδ(PKCδ) in CIA, FLS, and chondrocytes. Curcumin also suppressed the JNK and c-Jun activation in those cells. This study suggests that the suppression of MMP-1 and MMP-3 production by curcumin in CIA is mediated through the inhibition of PKCδand the JNK/c-Jun signaling pathway.

Complementary and alternative medicines are considered as a promising direction for the development of anti-allergic therapies in oriental countries. We screened approximately 100 oriental herbal medicines for anti-allergic activity. Sophorae flosexhibited the most potent effect on degranulation in antigen-stimulated mast cells. We further investigated the effect of Sophorae floson the IgE-mediated allergic response in vivoand its mechanism of action in mast cells. Sophorae flosexhibited a significant inhibitory effect on degranulation in antigen-stimulated mast cells with IC50values of ~31.6 μg/mL (RBL-2H3 mast cells) and ~47.8 μg/mL (bone marrow-derived mast cells). Sophorae flosalso suppressed the expression and secretion of TNF-α and IL-4 in the cells and IgE-mediated passive cutaneous anaphylaxis (PCA) in mice. Sophorae flosinhibited the activating phosphorylation of Syk and LAT in mast cells. Further downstream, activating phosphorylation of Akt and the prototypic MAP kinases, namely, p38, ERK1/2, and JNK, were also inhibited. These results suggest that Sophorae flosinhibits the Src family kinase-dependent signaling cascades in mast cells and may thus exert anti-allergic activity.

The process of different sorts of magnesium alloys investment casting is studied using a mold materials composed of zircon and colloided silica binder. The investment shell is flushed out employing protective gas mixture of 1% HFC134a and inert gas. The castings with perfect appearance and high metallurgical quality are produced successfully for ZC62 and ME-1magnesium alloy respectively. The mechanical properties of the castings reached the ASTM standard.

Isothermal grain coarsening of AlCu5MnCdVA aluminum alloy prepared by permanent mould casting during semi-solid treatment process was studied. It was found that the relationship between the average diameter of α (Al) grains and the isothermal holding time fitted the formula r − r = K ⋅ t − − ' 3 0 3 , where the coarsening rate K’ varied with the holding temperature, which equaled to 4.288×10-10m3/s and 5.962×10-10m3/s at the holding temperature. A modified model of liquid film migration has been proposed for explaining of 622°C and 631°C respectively the coarsening rate variation with annealing temperature. The diffusion of the solutes as well as vacancies, and the grain boundary tension are responsible for the microstructure evolution of AlCu5MnCdVA cast alloy.

The microstructure and surface micromorphology of ZnSe single crystals grown directly from zinc and selenium have been investigated using rotation orientation x-ray diffraction (RO-XRD), atomic force microscope (AFM) and field emission scanning electron microscope (FE-SEM). The ZnSe samples exhibit only the surface leaning to (111) singular face by the angle of 3.13°, which is the buildup of two-dimensional dendritic crystal layers. Numerous nuclei and cavities distribute unevenly across the crystal surface, governing the formation of growth layer, while the dendritic crystal layers develop rapidly by margining the smaller nuclei. The formation of these microstructure and micromorphology on the surface of ZnSe crystals depends on the surface supersaturation and the growth parameters.

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The constrained growth was observed during the formation process of the photonic crystals from the monodispersed PMMA colloidal microsphere and a controllable vertical deposition (CVD) technology was developed to prepare the photonic crystal based on these growth behaviors and the PMMA colloid particles with size of 345nm were assembled into the 3-D arrays. The transmittance spectrum of the typical sample exhibited an enlarged transmission mode. Their SEM observation revealed that the bulk structure of the crystalline array had a high periodical and long range order, the perfect order zone was above 20μm and the surface of the crystal was complete flat and had only two vacancies in the 3[removed info]5 μm order zone. The growth interface analysis indicated that the colloidal spheres sedimented subsequently and the drying front between the suspension and crystal moved at a constant velocity with time. The crystals developed by the continuous growth mechanism and the growing crystals had rough interface during the process of controllable vertical deposition.

Mast cells are responsible for IgE-mediated allergic reactions. Phospholipase D1 (PLD1) and PLD2 regulate mast cell activation, but the mechanisms remain unclear. Here we show that PLD2 associates with and promotes activation of Syk, a key enzyme in mast cell activation. Antigen stimulation resulted in increased association and colocalization of Syk with PLD2 on the plasma membrane as indicated by coimmunoprecipitation and confocal microscopy. This association was dependent on tyrosine phosphorylation of Syk but not on PLD2 activity. In vitro, PLD2 interacted via its Phox homology (PX) domain with recombinant Syk to induce phosphorylation and activation of Syk. Furthermore, overexpression of PLD2 or catalytically inactive PLD2K758R enhanced antigen-induced phosphorylations of Syk and its downstream targets, the adaptor proteins LAT and SLP-76, while expression of a PLD2 siRNA blocked these phosphorylations. Apparently, the interaction of PLD2 with Syk is an early critical event in the activation of mast cells.

In this study, the effects of BST204, a fermented ginseng extract, on the expression of inducible nitric oxide synthase (iNOS) and nitric oxide (NO) production are looked into. Crude ginseng extract was incubated with ginsenoside-β-glucosidase to prepare BST204. BST204, unlike lipopolysaccharide (LPS) and crude ginseng extract, did not affect the level of iNOS protein and NO production in unstimulated RAW 264.7 cells. However, it suppressed the level of iNOS protein and NO production in LPS-stimulated RAW 264.7 cells but did not manifest the same effect on the iNOS mRNA level. An investigation of the activating phosphorylation of p70 S6 kinase and 4E-BP1, which are important for translation, was conducted to investigate the suppressive mechanism of iNOS protein. LPS increased the phosphorylation of p70 S6 kinase, but not 4E-BP1, in a time-dependent manner, and BST204 inhibited it in a dose-dependent manner. The expression of iNOS protein, however, was partially suppressed by rapamycin, an upstream inhibitor of p70 S6 kinase. Therefore, this paper suggests that the suppression of iNOS protein by BST204 was partially correlated with the inhibition of p70 S6 kinase activation.

A method to predict the solid-liquid interface stability and the constrained dendrite growth of multi-component alloys was developed based on the Calphad method. The method was applied to several industrial Al-Si-Mg alloys, and the predicted results were compared with some former experimental data. The good agreement between the calculation results and the experimental data demonstrates the superiority of the present method to the classical one based on constant parameter assumptions.

Interface morphology and solute partition during directional solidification process of Al-1.5Cu-3.0Zn alloy were investigated at temperature gradient of 80K/cm and growth rate between 0.1 and 7.1µm/s. The solid-liquid interface was quenched during directional solidification and the micromorphology at the longitudinal section was examed by optic microscope and SEM. The cellular growth interface and dendritic growth interface were observed and characterized. The distribution of Cu and Zn was measured by EDS, the equilibrium solute partition coefficients for Cu and Zn in Al-1.5Cu-3.0Zn alloy were obtained to be 0.31 and 0.58. The activity model and concentration model, developed by present authors, were used to calculate the equilibrium solute partition coefficients in Al-1.5Cu-3Zn alloy. The model-calculated results were compared with experimental data.

The images of the growing crystal in the growth process of the undercooled droplets of silicon were lively recorded by using a high-speed camera. The number of crystal that nucleated spontaneously from the undercooled liquid was found to decrease to 1 when the undercooling was higher than 5K. The morphology of the growing single crystal of silicon was a thin plate. A model for predicting the critical undercooling of growing single crystal of silicon from undercooled liquid has been developed. The theoretically predicted value of the undercooling from present model for silicon is in agreement with the experimentally measured result.

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The optical properties of CdZnTe crystals grown by vertical Bridgman method were investigated in detail by infrared (IR) transmission spectra and photoluminescence (PL) spectra. IR transmission measurements showed that according to the trends of the IR transmission with the wavenumbers, IR transmission spectra could be classified into four types, i.e. descending, ascending, low straight and high straight. Each of them indicated one type of CdZnTe crystals with specified properties. PL measurements revealed that the low-temperature PL spectra consisted of three emissions: the near-band-edge emission (I0) situated at 1.66eV related to the free and bound excitons, the donor-acceptor emission (I1) centered at 1.62eV related to the impurities, and a defect band emission (I2) centered at 1.50eV due to the dislocations. The full width at half maximum (FWHM) of I0 and the PL intensity ratios of I1/I0 and I2/I0 could be used to evaluate the properties of the crystals.

Two chemical vapor transport methods with Zn(NH4)3Cl5 transport agent were developed to grow ZnSe bulk single crystals. Two kinds of Zn-rich ZnSe single crystals, conical crystal and flake crystal，were grown directly from untreated ZnSe polycrystals and two elements, respectively. The structure characters, purity and etch pit density were studied by rotating orientation XRD, PL spectrum and optical microscope. The contrastive investigation between two growth results indicated that the conical crystal was composed of (111) and (100) faces, and the flake crystal exhibited only (111) face. Moreover, the vicinal interface leaning to (111) face by the angle of 3.1° was the dominative growth face in vapor growth system, and growth occurs by layer-by-layer model. FWHM of RO-XRD pattern of ZnSe (111) face was 24sec for conical ZnSe crystal and 48s for ZnSe flake crystal. The results suggested that high-quality ZnSe crystals can be grown from the chemical vapor transport method with Zn(NH4)3Cl5 transport agent.

The bulk crystal growth of II-VI compounds, such as HgCdTe, CdZnTe etc., is usually carried out by Bridgman and modified Bridgman methods. Optimizing the growth process relies mainly on the understanding of the fundamental problems of solute and thermal transportation principles, which determines the composition segregations and other defects, including point defects, dislocations, precipitates, stacking faults, etc. In the last few years, the present author studied the coupling effects of the convection, thermal and solute transportation phenomena during the growth processes through both theoretical modeling and experimental methods. Several important phenomena, such as effects of ACRT forced convection on the thermal and solute field and the growth interface morphology, the shift of the growth interface due to the solute redistributions, solute segregation behaviors during the growth process, etc, are discussed. Based on these researches, technologies for growing high quality CdZnTe and other II-VI compounds have been developed.

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Yarrowialipolyticais a potentially useful host for heterologous protein production. To develop an efficient culture method for high cell density cultivation and heterologous gene expression of Y. lipolytica, the effects of medium components and their concentrations on the growth of Y. lipolyticahave been investigated. Addition of yeast extract to the culture media was found to significantly reduce the long lag phase encountered when Y. lipolyticawas cultivated in synthetic culture media containing high concentrations of glycerol. Therefore, by enriching with 0.3% yeast extract the synthetic culture medium containing 15% glycerol, we could cultivate Y. lipolyticaup to 83 g/L dry cell weight in a batch culture. Furthermore, over 100 g/L and 88 units/mL of rice α‐amylase activity were obtained in less than 50 h with a one‐step feeding process in which a recombinant Y. lipolyticaexpressing rice α‐amylase was cultivated in the 10% glycerol medium enriched with 0.3% yeast extract and fed only once with the concentrated feeding medium (60% glycerol). The easy cultivation of recombinant Y. lipolyticato a high cell density may strengthen its position as a host for heterologous protein production.

Motivated by the recent research of black holes with NUT charge, we investigate the validity of the weak cosmic censorship conjecture for the Kerr-Taub-NUT black hole with a test massive scalar field and a test particle, respectively. For the scalar field scattering gedanken experiment, we consider an infinitesimal time interval process. The result shows that both extremal and near-extremal Kerr-Taub-NUT black holes cannot be overspun. For the test particle thought experiment, the study suggests that the extremal Kerr-Taub-NUT black hole cannot be overspun; while the near-extremal Kerr-Taub-NUT black hole can be overspun. By comparing the two methods, the results indicate the time interval for particles crossing the black hole horizon might be important for consideration of the weak cosmic censorship conjecture. [ABSTRACT FROM AUTHOR]