Diamond-like carbon sintered compacts formed by spark plasma sintering

A spark plasma sintering (SPS) method was utilized for the novel production of diamond-like carbon (DLC) compacts. Two amorphous carbon powders with different particle sizes (45 μm and 24 nm diameter) were employed as starting materials for the sintering experiments. The carbon powders were sintered using a SPS system at various sintering temperatures and holding times. The structural properties of the sintered compacts were evaluated using X-ray diffraction (XRD) analysis and high-resolution transmission electron microscopy (HRTEM). Disk-shaped compacts were obtained by sintering the powder with a particle diameter of 45 μm, although the compacts were very brittle and easily broken. However, sintering of the 24 nm diameter powder particles at temperatures of 1473 to 1573 K with a holding time of 300 s led to the successful production of sintered compacts without breakage. Reflection peaks related to graphite structure were observed in XRD patterns of the compacts sintered from the 24 nm diameter particles. HRTEM analysis revealed that the compacts sintered at 1473 K with a holding time of 300 s had an amorphous structure and consisted of 34% sp³ carbon bonding. Evaluation of the structural properties indicated that sintered compacts with DLC structure could be created by the SPS method with 24 nm diameter amorphous carbon particles.     

Impacts of city-block-scale countermeasures against urban heat-island phenomena upon a building’s energy-consumption for air-conditioning

This study quantifies the possible impacts of urban heat-island countermeasures upon buildings’ energy use during summer in Tokyo metropolis. Considering the dependency of the buildings air temperature upon the local urban canopy structure, Tokyo urban canopies were classified in the city-block-scale using the sky-view factor (svf). Then, a multi-scale model system describing the interaction between buildings’ energy use and urban meteorological conditions was applied to each classified canopy.     

Calculation of mean velocity and discharge using water surface velocity in small streams

Calculation of mean velocity and discharge are very important for demands such as water management, water supply, irrigation and flood control. This paper presents to determine the mean velocity and discharge in small streams using based water surface velocity. For this purpose, flow measurements were carried out at four different cross-sections at eighteen field measurements in central Turkey. The mean velocities (U_m) were calculated using velocity–area method. (U_m) and water surface velocities (u_ws) at these stations exhibited a linear distribution as U_m=0.552u_ws which has R²=0.99 determination coefficient. It was observed that this constant was smaller than the literature value 0.85. The advantage of this ratio is that it does not change in T/R (T; width of cross-section, R; hydraulic radius) and Froude numbers for the small streams. Using this constant, mean velocities (U_mcal) and discharges (Q_mcal) for all measurements can be calculated. The average relative error between measured and calculated discharges (Q−Q_mcal) was found to be 4.08%. The results presented that this method can be utilized to determine the mean velocity and discharge in small streams successfully.     

Biomedical Application of Low Molecular Weight Heparin/Protamine Nano/Micro Particles as Cell- and Growth Factor-Carriers and Coating Matrix

Low molecular weight heparin (LMWH)/protamine (P) nano/micro particles (N/MPs) (LMWH/P N/MPs) were applied as carriers for heparin-binding growth factors (GFs) and for adhesive cells including adipose-derived stromal cells (ADSCs) and bone marrow-derived mesenchymal stem cells (BMSCs). A mixture of LMWH and P yields a dispersion of N/MPs (100 nm–3 μm in diameter). LMWH/P N/MPs can be immobilized onto cell surfaces or extracellular matrix, control the release, activate GFs and protect various GFs. Furthermore, LMWH/P N/MPs can also bind to adhesive cell surfaces, inducing cells and LMWH/P N/MPs-aggregate formation. Those aggregates substantially promoted cellular viability, and induced vascularization and fibrous tissue formation in vivo. The LMWH/P N/MPs, in combination with ADSCs or BMSCs, are effective cell-carriers and are potential promising novel therapeutic agents for inducing vascularization and fibrous tissue formation in ischemic disease by transplantation of the ADSCs and LMWH/P N/MPs-aggregates. LMWH/P N/MPs can also bind to tissue culture plates and adsorb exogenous GFs or GFs from those cells. The LMWH/P N/MPs-coated matrix in the presence of GFs may provide novel biomaterials that can control cellular activity such as growth and differentiation. Furthermore, three-dimensional (3D) cultures of cells including ADSCs and BMSCs using plasma-medium gel with LMWH/P N/MPs exhibited efficient cell proliferation. Thus, LMWH/P N/MPs are an adequate carrier both for GFs and for stromal cells such as ADSCs and BMSCs, and are a functional coating matrix for their cultures.     

Surface-active properties and thermal behavior of S-alkylthio-carboxylic acids and their potassium salts

S-Alkylthiocarboxylic acids and their potassium salts were prepared by photoaddition of α-olefins (C₁₀, C₁₂, and C₁₄) with mercapto carboxylic acids such as thiomalic acid, thiopropionic acid, and thioglycolic acid. The physicochemical solution properties and thermal stabilities for three series of thiosurfactants were evaluated. S-Alkylthiocarboxylic acids that contain bridged S-bonds provide excellent thermally stable surfactants, and their alkaline salts exhibit good surface activity.     

Enhancement of xylose uptake in 2-deoxyglucose tolerant mutant of Saccharomyces cerevisiae

Chemical mutation of Saccharomyces cerevisiae using ethyl methane sulfonate was performed to enhance its ability of xylose uptake for ethanol production from lignocellulose under microaerobic condition. Among the appeared mutants, the mutant no. 2 (M2) strain screened using inhibitory effects of 2-deoxyglucose (DOG) showed more than 4-fold high ability in xylose uptake compared with the wild type strain, under the presence of glucose. The catabolite repression by glucose was sufficiently reduced in M2 strain due to its tolerance to the high concentration of DOG (0.5%, wt./vol.). Metabolomic analyses of various sugars in the cell revealed that some of xylose was reduced to xylitol in M2 cell, providing the concentration gradient of xylose and more uptake of xylose. Xylulose-5-phosphate was significantly detected in the crude cell extract from M2 strain, indicating higher metabolic activity in pentose phosphate pathway. This was also confirmed by in vitro analyses of key enzymes involved in glucose and xylose metabolism, such as hexokinase, glucose-6-phosphate dehydrogenase and xylose reductase. Glucose uptake was moderately suppressed in the presence of trehalose-6-phosphate inhibiting the activation of hexokinase, resulting in more uptake of xylose through hexose transport system. To our knowledge, this study is the first report verifying that the mutation technique successfully enhances the xylose uptake by S. cerevisiae, particularly under the presence of glucose.     

Dynamic behaviors of nonlinear fractional-order differential oscillator

The nonlinear dynamic behaviors of oscillators described by fractional-order differential are presented in this paper. The background of the research is based upon two engineering practices. First is that the visco-elastic behaviors of some advanced polymeric materials can be accurately modeled by the fractional calculus constitutive law. Second is that the influence of nonlinear visco-elasticity described by the fractional operator cannot be neglected in some cases such as the vibration with large displacement or large strain and thermo-visco-elastic coupled problems. The numerical scheme for solving the nonlinear equation of motion is developed. The results show that because of the introduction of nonlinear damping modeled by the fractional-order operator, the bifurcation and chaos of the oscillator appear in forced vibration. Furthermore, the fraction value of the fractional operator evidently affects the dynamic behavior of the nonlinear fractional differential oscillator. This paper was presented at the 4th Asian Conference on Multibody Dynamics(ACMD2008), Jeju, Korea, August 20–23, 2008. Wei Zhang received his doctorate degree in Mechanics at Xi’an Jiaotong University in China in 1994. He went to the University Of Sheffield in the UK as an academic visitor from July 1986 to July 1987. He completed his post-doctorate study in Iwaki Meisei University in Japan through the support of the JSPS from May 1997 to June 1999. Dr. Zhang is currently a professor at the Department of Electronic Engineering of JiNan University in Guangzhou, China. Shao-kai Liao received his B.E. degree in Civil Engineering at JiNan University in Guangzhou, China in 2004 and his master’s degree in Engineering Mechanics at the same university in 2006. Mr. Liao was once a postgraduate student of Professor Wei Zhang, and he now works in an institute in Shenzhen City in China. Nobuyuki Shimizu received his B.S. degree in Mechanical Engineering at Yokohama National University and his master’s and doctorate degrees in Mechanical Engineering at University of Tokyo in 1968 and 1971, respectively. He went to the California Institute of Technology in California, U.S.A. as a visiting associate from October 1976 to September 1977. Dr. Shimizu is currently a professor at the Department of Mechanical and Power Engineering of Iwaki Meisei University in Japan.     

Fabrication of Al-3.7?Pct Si-0.18?Pct Mg Foam Strengthened by AlN Particle Dispersion and its Compressive Properties

Al-3.7 pct Si-0.18 pct Mg foams strengthened by AlN particle dispersion were prepared by a melt foaming method, and the effect of foaming temperature on the foaming behavior was investigated. Al-3.7 pct Si-0.18 pct Mg alloy containing AlN particles was prepared by noncompressive infiltration of Al powder compacts with molten Al alloy in nitrogen atmosphere, and it was foamed at different foaming temperatures ranging from 1023 to 1173 K. The porosity of prepared foam decreases and the pore structure becomes homogeneous with increasing foaming temperature. When the foaming temperature is higher than 1123 K, homogeneous pores are formed in the prepared ingot without using oxide particles and metallic calcium granules, which are usually used for stabilizing a foaming process. This stabilization of the foaming at high temperatures is possibly caused by Al₃Ti intermetallic compounds formed at high temperature and AlN particles. Compression tests for the prepared foams revealed that the absorbed energy per unit mass of prepared Al-3.7 pct Si-0.18 pct Mg foam is higher than those of aluminum foams strengthened by alloying or dispersion of reinforcements. It is remarkable that the oscillation in stress, which usually appears in strengthened aluminum foams, does not appear in the plateau stress region of the present Al-3.7 pct Si-0.18 pct Mg foam. The homogeneity in cell walls and pore morphology due to the stabilization of pore formation and growth by AlN and Al₃Ti particles is a possible cause of this smooth plateau stress region.     

GLYCEROL CONDENSATION PRODUCTS OF AMINOANTHRAQUINONES

Glycerol condensation reaction of 2- and 1-aminoanthraquinones was reexamined. 2-Aminoanthraquinone gave phenaleno[3,2-f]quinolin-7-one (10,11-pyridinobenzanthrone), 9H- phenanthro[10,1-gh]quinolin-9-one (4,5-pyridinobenzanthrone) and phenaleno[2,3-g]quinolin-7-one (10,9-pyridinobenzanthrone) besides phenaleno[2,3-f]quinolin-13-one (9,8-pyridinobenzanthrone) hitherto reported. 1-Aminoanthraquinone gave phenaleno[3,2-h]quinolin-13-one (8,9-pyridinobenzanthrone) along with a small amount of phenaleno[2,3-h]quinolin-7-one (11,10-pyridinobenzanthrone), but not 13H-phenanthro[1,10-gh]quinolin-13-one (6,5-pyridinobenzanthrone) as hitherto reported. NMR spectra of these six compounds were assigned and they supported the assigned isomeric structures.