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- Author or Editor: Z. Peng x
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Abstract
Positron annihilation lifetime spectra and ionic conductivity have been measured for poly(etherurethane)-LiClO4 as a function of temperature. The effects of Li salt on glas transition free volume and ionic conductivity have been discussed. A correlation between fractional free volume and ionic conductivity was first experimentally confirmed by using the free volume theory.
Abstract
Three samples of silicon dioxide were syhthesized and their surface areas were measured. A thermo-chemical cycle was designed to calculate the molar formation enthalpy. The molar formation enthalpy, Δf H m Φ, for three amorphous silica with the Langmuir surface area 198.0854, 25.1108 and 11.9821 m2 g−1 gave −895.52, −910.86 and −915.67 kJ mol−1, respectively. With the increasing surface area, the values of Δf H m Φ increased accordingly. The results suggest that the silica with larger surface area is more unstable. The wetting heat was also measured by adding the silica powder into water. With the rehydration of the more SiOH groups on the surface, the larger surface areas of silica lead to the more wetting heat. A smaller particle has the more unstable hydroxyl groups and surface energy.
Abstract
The biological activity of a kind of hetero-bimetallic Schiff-base complex was studied using Escherichia coli (E. coli) cell as the target. By microcalorimetry, the difference of anti-bacterial activity between the binuclear Schiff-base and the ligand was determined and analyzed. To analyze the inhibition of the bacterial growth internally, the E. coli cells grown in the presence of hetero-bimetallic Schiff-base complex were observed by scanning electron microscopy. The images in high resolution revealed the damage of outer cell membrane caused the inhibitory effect on E. coli. Inductively coupled plasma-mass spectrometry results proved the absorption of the complex by cells, which confirmed the interaction between the Schiff-base and biological macromolecule.
Abstract
The standard molar enthalpy of combustion of cholesterol was measured at constant volume. According to value of Δr U m θ(−14358.4±20.65 kJ mol−1), Δr H m θ(−14385.7 kJ mol−1) of combustion reaction and Δf H m θ(2812.9 kJ mol−1) of cholesterol were obtained from the reaction equation. The enthalpy of combustion reaction of cholesterol was also estimated by the average bond enthalpies. By design of a thermo-chemical recycle, the enthalpy of combustion of cholesterol were calculated between 283.15∼373.15 K. Besides, molar enthalpy and entropy of fusion of cholesterol was obtained by DSC technique.
Based on the known GA20-oxidase (GA20ox) cDNAs of barley and wheat, oligonucleotide primers were designed to isolate GA20ox genes from genomic DNA of Dasypyrum villosum. A total of 19 clones were obtained. Each of them contained an open reading frame encoding a putative 40-KDa protein of 359 amino acid residues. Twenty-one SNPs and 4 InDels were found and could divide the 19 sequences into 2 classes, designated as DvGA20ox-1 and DvGA20ox-2, respectively. Q-PCR analyses showed that both DvGA20ox-1 and DvGA20ox-2 were in leaf blade, leaf sheath, stem, eustipes, root and developing spike. Similar expression levels were found between DvGA20ox-1 and DvGA20ox-2 in three stages. The total expression levels of DvGA20ox-1 and DvGA20ox-2 presented downtrend in leaf blade and ascend in stem, eustipes and developing spike along with the development of plants, respectively. However, they were firstly increased and then decreased in root from seeding stage to heading stage. These results revealed that the gene expression profile of DvGA20ox-1 and DvGA20ox-2 closely related to the growth and development of D. villosum.
Doublesex and mab-3-related transcription factor 1 (Dmrt1) is a Z-linked gene that putatively determines the phenotype of gonads in birds. The sex differential expression of Dmrt1 was examined using wholemount in situ hybridization (WISH) in the urogenital systems during embryogenesis. The results revealed that Dmrt1 showed dimorphic expression in chicken gonads, which increased from day 6.5 to day 10.5. The expression of Dmrt1 in male (ZZ) gonads was not twice as much as in female (ZW) gonads, suggesting the existence of other regulatory mechanisms in addition to Z chromosome dosage effect.
Members of WRKY gene family encode transcription factors involved in plant developmental processes and response to biotic and abiotic stresses. In order to understand the function of the TaWRKY71 gene, a homologue gene was isolated and characterised in wheat (Triticum aestivum L.) genotype TAM107. Tissue-specific gene expression profiles indicated that TaWRKY71 was constitutively expressed in roots, stems, leaves, stamen and pistil. The relative expression of TaWRKY71 was elucidated under ABA treatment and other abiotic stresses. In agreement with this, several putative cis-acting elements involved in ABA-response, drought-inducibility, low-temperature and heat response were detected in the promoter region of TaWRKY71. The function of TaWRKY71 was further determined by transforming Arabidopsis thaliana. Transgenic plants over-expressing TaWRKY71 displayed enhanced seed germination under ABA treatment and were tolerant to salt and drought stresses. These results indicate that TaWRKY71 gene might play important roles in seed germination and abiotic stress response.
Abstract
Fluorine-18 produced by the18O(p,n)18F reaction on18O-water has proved to be highly useful as a source for a slow positron beam. About 70 GBq of18F is produced routinely by an ultra-compact cyclotron. The18F formed in H2 18O target is sent through a fine pipe to the site of positron slowing-down, fixed on a small spot by adsorption or drying, and then placed close to the moderator foil. An automatic apparatus has been set up for the entire process including the recovery of H2 18O.
Abstract
Chemical elemental compositions of some silicate, magnetic and glass spherules were investigated with INAA. The elements determined include Os, Ir, Ni, Co, Fe, Cr, Au, La, Ce, Sm, Eu, Yb, Lu and Sc etc. The elemental correlation, as well as their enrichment (or depletion) factors relative to Cl chondrite were examined. The high concentrations of the refractory siderophile elements contained in these spherules support the proposal that they originate from extraterrestrial substances. Some useful chemical criteria for identifying the sources of silicate, magnetic and glass spherules are put forward.
