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  • Author or Editor: J. Gao x
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Abstract  

A method utilizing plastic track detectors was developed to determine the nitrogen distribution and concentration in the presence of boron in metals. Experiments were performed at the UVAR (cadmium ratio ≈25) and the NIST Reactor (cadmium ratio ≈3000). The minimum detectable concentration of nitrogen at a given concentration of boron has been estimated using the detector’s response to10B(n,α)7 Li reaction products in terms of track size distribution. The capability of the technique to detect nitrogen in the presence of boron has been demonstrated using 316L stainless steel with a nitrogen concentration of ≈560 ppm and a boron concentration of ≈0.86 ppm.

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Abstract  

The catalytic performance of unsupported and carbon-supported Fe, Mo and Fe−Mo catalysts for Fischer-Tropsch synthesis is greatly influenced by the final reduction states of the catalysts. In this investigation, the reduction process of the catalysts by H2 was studied by using TG-DTG. The reduction process depends not only on the reducibility of metals but also on the nature of the support. Methanation of the support occurred as soon as the supported metals were completely reduced for the carbon-supported catalysts. For these, the reduction temperature should by carefully selected so that the metal oxides are reduced as completely as possible, whilst the methanation of the support must be avoided to obtain optimum reduced catalysts.

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Abstract  

Carburization and coke deposition of unsupported and carbon-supported Fe, Mo and Fe−Mo catalysts in syngas have been studied using thermogravimetry. Compositions of the carbides formed are evaluated on the basis of the amount of metals in the catalysts and amount of carbon deposited during carburization. It is shown that carburization temperature and the nature of the carbides formed (Fe5C2 and Fe2C for iron and Mo2C for molybdenum) depend on the metals but are influenced by the support and metal loading. Coke deposition on these catalysts takes place as soon as carburization is complete.

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Abstract  

The thermal decomposition behaviour of the complexes of rare earth metals with histidine: RE(His)(NO3)3 H2O (RE=La—Nd, Sm—Lu and Y; His=histidine) was investigated by means of TG-DTG techniques. The results indicated that the thermal decomposition processes of the complexes can be divided into three steps. The first step is the loss of crystal water molecules or part of the histidine molecules from the complexes. The second step is the formation of alkaline salts or mixtures of nitrates with alkaline salts after the histidine has been completely lost from the complexes. The third step is the formation of oxides or mixtures of oxides with alkaline salts. The results relating to the three steps indicate that the stabilities of the complexes increase from La to Lu.

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Among the progenies of crossing Triticum turgidum — Haynaldia villosa amphiploid with synthetic hexaploid wheat (T. carthlicum / Aegilops tauschii) Am3, two lines (SN030713 and SN05078), with good resistance to stripe rust and powdery mildew, were developed. Cytological studies demonstrated that SN030713 contained 42 chromosomes and formed 21 bivalents at meiotic metaphase I. SN05078 contained 28 chromosomes and formed 14 bivalents. Genomic in situ hybridization analysis using H. villosa V genomic DNA as the probe showed SN030713 and SN05078 had no large H. villosa chromosome fragments. PCR analysis with H. villosa specific primer pHv29 showed that H. villosa genetic materials were introgressed in these two lines. SSR analysis indicated that the genomic composition of SN030713 was 2n = 6x = 42 (AABBDD), and SN05078 was 2n = 4x = 28 (AABB). Introgressed Ae. tauschii genetic materials in SN05078 were also detected.

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Abstract  

Poly(AN—co—St) (PAS) and poly(AN—St—MMA)(PASM) were synthetized by emulsion polymerisation. The glass transition temperatures (T g) of the copolymers and the relationship between T g and the components of the copolymers were investigated by differential scanning calorimetry. The results show that T g for the AN—St bipolymers has apeak value in the range 115–118°C at a content of 50 mass% St. When methyl methacrylate was added, the T g of the terpolymer was decreased by about 2–6°C.The thermostability and the activation energy E of degradation were determined by thermogravimetric analysis.

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This study was designed to test the hypothesis that a medium-term simulated microgravity by tail-suspension (SUS) induces hypertrophic and atrophic changes in the common carotid artery and abdominal aorta with their innermost smooth muscle (SM) layers being most profoundly affected. The second purpose was to elucidate whether vascular local renin-angiotensin system (L-RAS) plays an important role in the differential remodeling of the two kinds of large arteries by examining the gene and protein expression of angiotensinogen (A O ) and angiotensin II receptor type 1 (AT1R) and their localization in the vessel wall. The results showed that SUS induced an increase in the media thickness of the common carotid artery due to hypertrophy of the four SM layers and a decrease in the total cross-sectional area of the nine SM layers of the abdominal aorta without significant change in its media thickness. Irrespective of the nature of remodeling, the most prominent changes were in the innermost layers. Immunohistochemistry, in situ hybridization, Western blot, and real time quantitative PCR analysis revealed that SUS induced an up- and down-regulation in A O and AT1R expression in the common carotid artery and abdominal aorta, respectively. In conclusion, our findings have demonstrated some special features in the structural adaptation of large elastic arteries due to a medium-term simulated microgravity.

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Abstract

Phase change materials (PCM) have been extensively scrutinized for their widely application in thermal energy storage (TES). Paraffin was considered to be one of the most prospective PCMs with perfect properties. However, lower thermal conductivity hinders the further application. In this letter, we experimentally investigate the thermal conductivity and energy storage of composites consisting of paraffin and micron-size graphite flakes (MSGFs). The results strongly suggested that the thermal conductivity enhances enormously with increasing the mass fraction of the MSGFs. The formation of heat flow network is the key factor for high thermal conductivity in this case. Meanwhile, compared to that of the thermal conductivity, the latent heat capacity, the melting temperature, and the freezing temperature of the composites present negligible change with increasing the concentration of the MSGFs. The paraffin-based composites have great potential for energy storage application with optimal fraction of the MSGFs.

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