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- Author or Editor: H. Song x
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Summary
A new high-performance liquid chromatography (HPLC) method has been developed and validated for determination of enantiomeric purity of thiazolidine-2-carboxylic acid within a short run time of less than 10 min. The method was based on pre-column derivatization of thiazolidine-2-carboxylic acid with aniline, and complete separation of enantiomers has been achieved on a Chiralcel OD-H analytical column (250 × 4.6 mm) using n-hexane-isopropanol (85:15 v/v) as mobile phase at a flow rate of 1.0 mL min−1 under UV and optical rotation (OR) detection. Detection wavelength was set at 254 nm. Then the effects of mobile phase and temperature on enantioselectivity were further evaluated. The method was validated with respect to precision, accuracy, linearity, limit of detection (LOD), limit of quantification (LOQ), and robustness. The recoveries were between 98.5 and 101.3% with percentage relative standard deviation less than 1.16%. The LOD and LOQ for the aniline derivatives of (+)-thiazolidine-2-carboxylic acid were 4.9 and 16.4 μg mL−1 and for the aniline derivatives (−)-thiazolidine-2-carboxylic acid were 5.1 and 17.2 μg mL−1, respectively.
Abstract
Polyimide BTDA-ODA sample was prepared by polycondensation or step-growth polymerization method. Its low temperature heat capacities were measured by an adiabatic calorimeter in the temperature range between 80 and 400 K. No thermal anomaly was found in this temperature range. A DSC experiment was conducted in the temperature region from 373 to 673 K. There was not phase change or decomposition phenomena in this temperature range. However two glass transitions were found at 420.16 and 564.38 K. Corresponding heat capacity increments were 0.068 and 0.824 J g–1 K–1, respectively. To study the decomposition characteristics of BTDA-ODA, a TG experiment was carried out and it was found that this polyimide started to decompose at ca 673 K.
Abstract
In this study, the ability of microRNA-1906 (miR-1906) to attenuate bone loss in osteoporosis was evaluated by measuring the effects of a miR-1906 mimic and inhibitor on the cellular toxicity and cell viability of MC3T3‐E1 cells. Bone marrow-derived macrophage (BMM) cells were isolated from female mice, and tartrate-resistant acid phosphatase signalling was performed in miR-1906 mimic-treated, receptor-activated nuclear factor kappa-B (NF-κB) ligand (RANKL)-induced osteoclasts. In-vivo, osteoporosis was induced by ovariectomy (OVX). Rats were treated with 500 nmol/kg of the miR-1906 mimic via intrathecal administration for 10 consecutive days following surgery. The effect of the miR-1906 mimic on bone mineral density (BMD) in OVX rats was observed in the whole body, lumbar vertebrae and femur. Levels of biochemical parameters and cytokines in the serum of miR-1906 mimic-treated OVX rats were analysed. The mRNA expression of toll-like receptor 4 (TLR4), myeloid differentiation primary response 88 (MyD88), p-38 and NF-κB in tibias of osteoporotic rats (induced by ovariectomy) was observed using quantitative reverse-transcription polymerase chain reaction. Treatment with the miR-1906 mimic reduced cellular toxicity and enhanced the cell viability of MC3T3‐E1 cells. Furthermore, osteoclastogenesis in miR-1906 mimic-treated, RANKL-induced osteoclast cells was reduced, whereas the BMD in the miR-1906 mimic-treated group was higher than in the OVX group of rats. Treatment with the miR-1906 mimic also increased levels of biochemical parameters and cytokines in the serum of ovariectomised rats. Finally, mRNA expression levels of TLR4, MyD88, p-38 and NF-κB were lower in the tibias of miR-1906 mimic-treated rats than in those of OVX rats. In conclusion, the miR-1906 mimic reduces bone loss in rats with ovariectomy-induced osteoporosis by regulating the TLR4/MyD88/NF‐κB pathway.
Abstract
The sorption/desorption of radioruthenium was investigated by the batch method in sea water system at ambient temperature on the surface sediments obtained around the Daya Bay of Guangdong Province, where the first nuclear power station of China has been running from 1994. It was found that the sorption percentage was obtained to be around 40% for all the surface sediments in 60 minutes. Then, the sorption percentage goes up slowly. The sorption percentage of radioruthenium reached around 80% in 113 days (2713 hours). The distribution coefficients decreased from 3.16·104 to 1.35·103 ml/g with the increasing of sediment concentration in the range of 4–10000 mg/l. The results of the desorption experiments suggest that the sorption of radioruthenium is irreversible with 81.5% relative hysteresis coefficient.
Abstract
Three kinds of marine bivalves (wild Saccostrea cucullata, aquacultured Perna viridis and aquacultured Pinctada martens), collected from Daya Bay, the South China Sea, were used to investigate the bio-accumulation of radioruthenium in the glass aquarium with natural seawater (pH 8.20, 35‰ salinity, filtered by 0.45 μm) at ambient temperature under laboratory feeding conditions. The experimental results show that the stead-state of biology concentration factor (BCF, ml/g) of radioruthenium was approached around 6 days for most species of bivalves. The values of BCF in shells are the highest in organs all the three bivalves. The orders of BCF values (ml·g−1) are as: Perna viridis (33.2) < Saccostrea cucullata (47.0) < Pinctada martensi (208.4) for shells and Saccostrea cucullata (1.5) < Pinctada martensi (2.2) ≈ Perma viridis (2.4) for soft tissues, respectively, after exposed for 14 days. The rate constants of uptake and elimination of radioruthenium on marine bivalves were also discussed by first-order kinetics model. The Pinctada martensi may be applicable to be an indicator for monitoring radioruthenium among the three bivalves.
Abstract
3,3-Dinitroazetidinium (DNAZ) salt of perchloric acid (DNAZ·HClO4) was prepared, it was characterized by the elemental analysis, IR, NMR, and a X-ray diffractometer. The thermal behavior and decomposition reaction kinetics of DNAZ·HClO4 were investigated under a non-isothermal condition by DSC and TG/DTG techniques. The results show that the thermal decomposition process of DNAZ·HClO4 has two mass loss stages. The kinetic model function in differential form, the value of apparent activation energy (E a) and pre-exponential factor (A) of the exothermic decomposition reaction of DNAZ·HClO4 are f(α) = (1 − α)−1/2, 156.47 kJ mol−1, and 1015.12 s−1, respectively. The critical temperature of thermal explosion is 188.5 °C. The values of ΔS ≠, ΔH ≠, and ΔG ≠of this reaction are 42.26 J mol−1 K−1, 154.44 kJ mol−1, and 135.42 kJ mol−1, respectively. The specific heat capacity of DNAZ·HClO4 was determined with a continuous C p mode of microcalorimeter. Using the relationship between C p and T and the thermal decomposition parameters, the time of the thermal decomposition from initiation to thermal explosion (adiabatic time-to-explosion) was evaluated as 14.2 s.
In this study, we employed electron microscopy to investigate the cytogenetic and embryologic mechanisms of parthenogenesis induced in the 1BL/1RS male sterile lines of wheat. Analysis of the root tips and acid polyacrylamide gel electrophoresis indicated that all of the male sterile lines and their maintainer lines were 1BL/1RS translocation lines, whereas the restorer lines were non-1BL/1RS translocation lines. Furthermore, the chromosomes of 1BL/1RS wheat lines with T. aestivum cytoplasm and Aegilops cytoplasm (include Ae. kotschyi, Ae. ventricosa, Ae. variabilis) paired abnormally at different rates during meiotic metaphase I (MMI). The translocated segment size of the 1RS chromosome and the specific nuclear–alloplasm interaction impaired the pairing of homologous chromosome in the background of the specific Aegilops cytoplasm at MMI. In addition, the frequency of abnormal chromosomal pairing was directly affected by the frequency of haploid production induced by parthenogenesis. The results of this study provide significant insights into the mechanism of parthenogenesis, which is probably due to the abnormal fertilization of synergid cells in alloplasmic 1BL/1RS wheat.
Abstract
The heat capacities of fenpropathrin in the temperature range from 80 to 400 K were measured with a precise automatic adiabatic calorimeter. The fenpropathrin sample was prepared with the purity of 0.9916 mole fraction. A solid—liquid fusion phase transition was observed in the experimental temperature range. The melting point, T
m, enthalpy and entropy of fusion, 
fus
H
m,
fus
S
m, were determined to be 322.48±0.01 K, 18.57±0.29 kJ mol–1 and 57.59±1.01 J mol–1 K–1, respectively. The thermodynamic functions of fenpropathrin, H
(T)—H
(298.15), S
(T)—S
(298.15) and G
(T)—G
(298.15), were reported with a temperature interval of 5 K. The TG analysis under the heating rate of 10 K min–1 confirmed that the thermal decomposition of the sample starts at ca. 450 K and terminates at ca. 575 K. The maximum decomposition rate was obtained at 558 K. The purity of the sample was determined by a fractional melting method.
Summary
The comprehension of the behavior of radioactive nuclides in aquifer requires the study of the sorption processes of nuclides in various geochemical conditions. The sorption/desorption of 65Zn(II) on surface sediments (0-2 cm) was investigated by batch method in sea water (pH 8.20, 35‰ salinity, filtered by 0.45mm) at ambient temperature. The surface sediments were obtained from four stations around the Daya Bay of Guangdong Province (China), where the first nuclear power station of China has been running from 1994. The sorption process is fast initially and around 39% average of sorption percentage (SP%) can be quickly obtained in 15 minutes for all the surface sediments. Then, the sorption percentage becomes constant. In 30 days of contact time 79.6% sorption percentage and K d=3.9. 103ml/g distribution coefficient was obtained. The value of K dbecame constant, 4.0. 103ml/g, in contact time more than 120 hours. The distribution coefficient K ddecreases with increasing sediment concentration from 4.0 to 250 mg/l from 1.31. 104to 1.68. 103ml/g, respectively. Then the value of K dgoes up to 5.38. 103ml/g with sediment concentration of 3000 mg/l. The desorption experiments suggest that the sorption of Zn(II) is irreversible with a hyteresis coefficient of 66%.
A novel 4.0-kb Fy was sequenced and bacterially expressed. This gene, the largest y-type HMW-GS currently reported, is 4,032-bp long and encodes a mature protein with 1,321 amino acid (AA) residues. The 4.0-kb Fy shows novel modifications in all domains. In the N-terminal, it contains only 67 AA residues, as three short peptides are absent. In the repetitive domain, the undecapeptide RYYPSVTSPQQ is completely lost and the dodecapeptide GSYYPGQTSPQQ is partially absent. A novel motif unit, PGQQ, is present in addition to the two standard motif units PGQGQQ and GYYPTSPQQ. Besides, an extra cysteine residue also occurs in the middle of this domain. The large molecular mass of the 4.0-kb Fy is mainly due to the presence of an extra-long repetitive domain with 1,279 AA residues. The novel 4.0-kb Fy gene is of interest in HMW-GS gene evolution as well as to wheat quality improvement with regard to its longest repetitive domain length and extra cysteines residues.
