[Study on the Temperature Dependent Phase Transformation of Raman Spectra for Cyclobutanol].

Cyclobutanol (C4H8O) is one of the four-membered ring type molecules, which usually adopts a non-planar equilibrium conformation, and the substituent group OH can adopt two positions relative to the puckered ring, the axial or the equatorial, giving rise to an additional degree of freedom and various molecular conformations. Additionally, temperature is one important thermodynamic parameter that greatly influents the structure and induces the possibility of conformational change or crystal change. As a consequence, there may be a number of phase transitions and molecular conformations for cyclobutanol under different temperature. In this paper, Raman and infrared spectroscopic technique were applied to investigate the vibration modes of cyclobutanol. The results indicate that the main component of the liquid cyclobutanol is equatorial-trans (Eq-t) conformer with a few Eq-g conformers at ambient condition. Then differential scanning calorimetry (DSC) and low temperature Raman spectroscopic were applied to study the phase transition of cyclobutanol during the cooling and heating process. It is observed that the Raman spectra and the intensities of these bands are not significantly changed during the cooling process. The results indicate that there is sill no presence of solidification especially cooling to 140K, which indicates that the cyclobutanol still remains the liquid state and supercooled state is observed during the cooling process. And this supercooled liquid is one metastable state, not in thermodynamic equilibrium. Further cooling to 138 K, the super-cooling liquid cyclobutanol will transform into the glassy state, accompanied with a small change of entropy. During the heating process, as the temperature is raised to 180 K, the Raman peaks became sharper and some new characteristic peaks appeared abruptly and a discontinuous change was observed in bandwidths versus temperature. And these new signatures can be maintained upon to 220 K, and then will disappear as the temperature increasing continuously. This result indicates the one crystal phase transition and a melting transition present at around 180 and 220 K. In addition, it can be observed that the component of Eq-g conformer increases, accompanied with the crystallization during heating at around 180 K. These results were helpful to understand the kinetics of the crystallization process of other small organic molecules.

[Effects of polybrominated diphenyl ether-153 lactation exposure on the concentrations of intracellular calcium ion and calcium-activated related enzymes levels of adult rats' cerebral cortex].

OBJECTIVE: To investigate the effects of polybrominated diphenyl ether-153 (BDE-153) exposure during lactation period on the calcium ion (Ca(2+)) concentration and calcium-activated enzyme levels in cerebral cortical cells among adult rats and to provide a scientific basis for the study on the developmental neurotoxicity of BDE-153. METHODS: Forty newborn male rats were randomly and equally divided into four groups according to their body weights and litters: 1, 5, and 10 mg/kg BDE-153 groups and olive oil solvent control group. On postnatal day 10 (PND 10), the BDE-153 groups were administrated BDE-153 (0.1 ml/10 g body weight) by intraperitoneal injection, while the olive oil solvent control group was given an equal volume of olive oil. Two months later, these rats were decapitated, and the cerebral cortex was separated quickly on an ice-cold dish. The Ca(2+) concentration in cerebral cortical cells was measured by flow cytometry. The activities of calcineurin (CaN) and Ca(2+)-Mg(2+)-ATP enzyme were determined by colorimetric method. The mRNA and protein expression of calpain-1 and calpain-2 was measured by real-time quantitative PCR and Western blot. RESULTS: The mean fluorescence intensities of intracellular Ca(2+) in control group and 1, 5, and 10 mg/kg BDE-153 groups were 10.83, 1.48, 1.93, and 0.62, respectively; the 1, 5, and 10 mg/kg BDE-153 groups had significantly lower intercellular Ca(2+) concentrations than the control group (P < 0.05). The activities of CaN and Ca(2+)-Mg(2+)-ATP enzyme and mRNA and protein expression of calpain-1 showed no significant differences between the 1, 5, and 10 mg/kg BDE-153 groups and control group (P > 0.05). The protein expression of calpain-2 increased as the dose of BDE-153 rose. Compared with the control group (mRNA: 0.81±0.26; protein: 0.15±0.07), the 5 and 10 mg/kg BDE-153 groups had significantly higher mRNA expression of calpain-2 (5 mg/kg BDE-153 group: 1.16±0.52; 10 mg/kg BDE-153 group: 1.32±0.23) and significantly higher protein expression of calpain-2 (5 mg/kg BDE-153 group: 0.31±0.07; 10 mg/kg BDE-153 group: 0.37±0.06) (P < 0.05). The 10 mg/kg BDE-153 group had significantly higher protein expression of calpain-2 than the 1 mg/kg BDE-153 group (0.37±0.06 vs 0.22±0.07, P < 0.05). CONCLUSION: Ca(2+-) mediated calpain-2 activation may be one of the main mechanisms of BDE-153 neurotoxicity.

Simultaneous determination of malachite green, crystal violet, methylene blue and the metabolite residues in aquatic products by ultra-performance liquid chromatography with electrospray ionization tandem mass spectrometry.

This work describes solid-phase extraction-ultra-performance liquid chromatography with electrospray ionization tandem spectrometry for determination of malachite green and metabolite leucomalachite green, crystal violet and metabolite leucocrystal violet, methylene blue and metabolites including azure A, azure B and azure C in aquatic products. Samples were extracted with acetonitrile and ammonium acetate buffer and purified by liquid extraction with dichloromethane, and then on MCAX solid-phase extraction cartridges. Then the extract was evaporated at 45°C by nitrogen blow. The residue was dissolved and separated by an Acquity BEH C18 column. The mobile phase was acetonitrile (A) and 5 mmol/L of ammonium acetate containing 0.1% formic acid (B). Analytes were confirmed and quantified using a tandem mass spectrometry system in multiple reaction mode with triple quadrupole analyzer using positive polarity mode. The limits of detection of malachite green, leucomalachite green, crystal violet and leucocrystal violet were 0.15 µg/kg, the limits of quantification were 0.50 µg/kg, and the average recoveries were more than 75% with spiked residues from 0.5 to 10 µg/kg. The relative standard deviations were less than 13%. The limits of detection of methylene blue, azure A, azure B and azure C were 0.3 µg/kg, the limits of quantification were 1.0 µg/kg, the average recoveries were more than 70% with spiked residues from 1.0 to 10 µg/kg and the relative standard deviations were less than 15%. The method has the merits of simplicity, sensitivity and rapidity, and can be used for simultaneous determination of the analytes in aquatic products.