Effect of CH3OOH on the atmospheric concentration of OH radicals

Methyl hydroperoxide (CH₃OOH, MHP) is known to be a significant sink and reservoir of HO_x and RO_x radicals in the atmosphere. In order to investigate the impact of MHP on the concentration of atmospheric OH radicals, two key gas-phase reactions of MHP, i.e. the reactions with OH radicals and with UV photolysis, have been simulated at temperature of 293±2 K and total pressure of 1.01×10⁵ Pa, using the long path Fourier transform infrared (LP-FTIR) spectrometry. OH radicals are generated by the photolysis of O₃ in the presence of water vapor. Combined with the relative rate method, the reaction rate constant of MHP with OH radicals is determined to be (3.99±0.15)×10^-12 cm³?molecule^-1?s^-1, and thus the atmospheric lifetime of MHP is estimated at 2.9 days. Furthermore, from detailed analysis of the UV photolysis of MHP, the yield of OH radicals is obtained to be 0.91±0.04. Based on the MHP atmospheric lifetime and the yield of OH radicals, it is concluded that MHP plays an essential role in the redistribution of OH radicals in the troposphere.     

Effect of CH3OOH on the atmospheric concentration of OH radicals

Methyl hydroperoxide (CH₃OOH, MHP) is known to be a significant sink and reservoir of HO_x and RO_x radicals in the atmosphere. In order to investigate the impact of MHP on the concentration of atmospheric OH radicals, two key gas-phase reactions of MHP, i.e. the reactions with OH radicals and with UV photolysis, have been simulated at temperature of 293±2 K and total pressure of 1.01×10⁵ Pa, using the long path Fourier transform infrared (LP-FTIR) spectrometry. OH radicals are generated by the photolysis of O₃ in the presence of water vapor. Combined with the relative rate method, the reaction rate constant of MHP with OH radicals is determined to be (3.99±0.15)×10^-12 cm³?molecule^-1?s^-1, and thus the atmospheric lifetime of MHP is estimated at 2.9 days. Furthermore, from detailed analysis of the UV photolysis of MHP, the yield of OH radicals is obtained to be 0.91±0.04. Based on the MHP atmospheric lifetime and the yield of OH radicals, it is concluded that MHP plays an essential role in the redistribution of OH radicals in the troposphere.     

固体超强酸SO2－4／ZrO2形成机理的研究

The formation of SO^2－₄／ZrO₂ solid superacid is studied with FT-IR、XRD and SEM techniques．Subtractive FT-IR measurement indicates the existence of chemical bonds between ZrO₂  and H₂SO₄,XRD determination reveals that the strength of SO^2－₄／ZrO₂ superacid strongly depends on temperature of calcination and reaches a maximum as the ZrO₂ transforms into tetragonal crystal phase.SEM analysis shows that the morphology of ZrO₂ surface is changed due to treatment of H₂SO₄.This catalyst shows higher esterification activity for synthesis of dibutyl moleate which is excellently related with the results of surface analysis.     

Reliability Analysis of Wind Turbine Gearbox Based on the Optimal Confidence Limit Method

Based on the zero-failure data of 30 Chinese 1. 5 MW wind turbine gearboxes（ WTGs）,the optimal confidence limit method was developed to predict the reliability and reliability lifetime of WTG. Firstly,Bayesian method and classical probability estimation method were introduced to estimate the value interval of shape parameter considering the engineering practice. Secondly,taking this value interval into the optimal confidence limit method,the reliability and reliability lifetime of WTG could be obtained under different confidence levels. Finally,the results of optimal confidence limit method and Bayesian method were compared. And the comparison results show that the rationality of this estimated range.Meantime, the rule of confidence level selection in the optimal confidence limit method is provided, and the reliability and reliability lifetime prediction of WTG can be acquired.     

New evidence for microstructural evolution model of acid-activated montmorillonite

Ca-montmorillonite samples from Choushan treated at various acid concentrations were studied using chemical analysis, XRD, ²⁹Si and ²⁷Al MAS NMR, to investigate the microstructure of the activated montmorillonites. With the increase of acid concentration and dissolution of cations of montmorillonite, the intensity of d(001) decreased obviously and significant changes of the microstructure of Si and Al occurred. There were two new types of structural units of Si atoms formed: (SiO)₃SiOH units and Q⁴(0Al) units. For Al atoms, in the course of activation, the removal of one of a pair of octahedral aluminium atoms from montmorillonite removed two hydroxyl groups and left the other aluminum of the pair in the four-fold coordination. The ²⁷Al signal at δ 54.0 corresponding to Al^Ⅳ arose from the four- coordinated Al in the octahedral sheet. This study first con-firmed, by ²⁹Si and ²⁷Al MAS NMR spectra, that the model of microstructural evolution for activated montmorillonite postulated by Thomas et al. (1950) is correct.     

Effect of solvents on the barrierless reaction in the excited state of cyanine dye

UV－Vis,fluorescence spectroscopy and time resolved spectroscopic technique on picosecond and femto-second scales have been utilized to investigate the effect of steric hindrance and multiple hydroxyl groups of solvents on the barreierless isomerization in excited state of 3,3 ′-di(3-sulfopropyl)thiacyanine triethylamminium salt,The results show that the factors mentioned above may be responsible for a different “short-time behavior “of the bleaching signal on the ground state and nonlinear viscosity dependence of the excited-state lifetime in ispropanol and glycol,These phenomena are distinguished from the situation repored in the long-chained monhydroxyl alcoloh solvents.However,the dye molecule still exhibits the analyzing-wavelength dependence of the observed fluorescence lifetime,that is ,the fluorescence lifetime increases with the increasing of analyzing-wavelength ,The conclusions are in agreement with those drawn from femtosecond upconversion fluorescence experiments and further exemplify the barrierless isomerization model in the excited state.     

The possible contribution of a mantle-derived fluid to the Ningwu porphyry iron deposits-Evidence from carbon and strontium isotopes of apatites

Apatite is a characteristic mineral for the iron deposits in the Ningwu region. Apatite shows a range of δ¹³CPDB values from -9.6 ‰ to -0.6‰, and most of them with the δ¹³CPDB values distributed in a range of mantle carbon (i.e., ﹣2‰ to -9‰) except for samples T-06-1and J-06-3. Apatites in the Ningwu porphyry iron deposits yield a narrow variation range of ⁸⁷Sr/⁸⁶Sr values from 0.706326 to 0.707577, similar to those of the volcanic and subvolcanic rocks and lower than those of a typical mantle-derived magmatic apatite (i.e., about 0.7040), indicating that formation of the apatites were involved with crust material contamination. Δ¹³CPDB and ⁸⁷Sr/⁸⁶Sr values of the apatite indicate a possible contribution of mantle-derived fluid and material to formation of the Ningwu porphyry iron deposits, supported by regional geology, regional gravities and geochemistry of the volcanic and subvolcanic rocks in the Ningwu region.     

Chemical quenching and inhibition of positronium in Cr<Subscript>2</Subscript>O<Subscript>3</Subscript>/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> catalysts

The pore structure of Cr2O3/Al2O3 catalysts and the surface chemical properties of these pores were characterized by positron lifetime and coincidence Doppler broadening (CDB) measurements. Four lifetime components could be resolved from the positron lifetime spectrum, with two long lifetime components and two short lifetime components. The two long lifetimes τ4 and τ3 are attributed to ortho-positronium (o-Ps) annihilation in large pores and microvoids, respectively. With increasing Cr2O3 content, both τ4 and its intensity I4 show sharp decrease, while τ3 and its intensity I3 keep nearly unchanged. The Doppler broadening S parameters also show sharp decrease with increasing Cr2O3 content. Detailed analysis of the CDB spectrum reveals that the parapositronium (p-Ps) intensity also decreases with increasing Cr2O3 content. This indicates that the change of o-Ps lifetime τ4 is due to the chemical quenching by Cr2O3 but not spin-conversion of positronium. The decrease of o-Ps intensity I4 indicates that Cr2O3 also inhibits positronium formation.     

Estimation of the rational wa-ter area for controlling wind erosion in the dried-up basin of the Ebinur Lake and its effect detection

The Ebinur Lake region was described as a “Green Labyrinth” in “Xinjiang Map Records: Records of Rivers” published in 1910, however, the ecology and environment in the region have been seriously degenerated due to the impacts of human activities during the recent 40 years. A dried-up lake basin with an area of 107.4 km² forms in its northwestern part, is covered by unconsolidated silt deposit without vegetation, and has become one of the main dust sources of dust weathers in north Xinjiang, and the dust with an annual amount of 4.8×10⁶ t is blown out of the region by strong winds from the Alataw mountain-gap where there are 164 days occurring strong winds in a year. The rational water area and inflow of the Ebinur Lake for improving the ecology in the lake region and effectively controlling wind erosion in the dried-up lake basin are estimated using the water balance equation after analyzing the current ecological problems and the relationship be-tween the granular composition of deposit in the dried-up lake basin and the dust weathers, and the ecological effects in recent years are monitored. It is considered that the water area of the Ebinur Lake for improving the ecology in the lake region and effec-tively controlling wind erosion in the dried-up lake basin should be 800 km² at least, and the annual volume of surface runoff and groundwater recharging the lake should be over 7.92×10⁸ m³.     

Thymidine kinase gene mutation leads to reduced virulence of pseudorabies virus

To explore correlation between the tk gene structure of pseudorabies virus (PRV) and its virulence, to study the effect of the gene mutation on PRV biological properties, and to investigate mechinism of reduced virulence, thymidine kinase (TK)-deficient mutant of pseudorabies virus strain Hubei (PRV HB) was isolated by selection for resistance to 5-bromodeoxyuridine. The tk genes of PRV HB and its TK^― mutant were cloned and sequenced. 1587 base pairs of the tk gene and flanking regions of wild-type (wt) virus were sequenced, which included an open reading frame (ORF) of 1098 bp encoding a protein of 366 amino acids. The ORF contained two 137-bp repeated sequences, which were connected by an adenosine. 1458 bp of the tk and flanking regions of TK^― mutant were sequenced. Analysis of the tk gene sequence of TK^― mutant indicated that one of 137 bp repeated sequence and the connecting adenosine in the tk gene of the wt virus was deleted and a repeated sequence of 8 nucleotides (GCGCGCC) was inserted. All other nucleotides of TK^―mutant were identical to that of wt virus. Deletion and insertion of the nucleotide sequence resulted in a frameshift and a premature chain termination, and the resultant TK protein was not active. Analysis of the amino acid sequence revealed that TK protein of PRV HB contained the conserved consensus sequence of herpesviral TKs and an additional conserved-DHR-motif. The results of this work also indicated that TK^― mutant was genetically stable. Compared to PRV HB, virulence of TK^― mutant was greatly decreased. Mice vaccinated with TK^― mutant were completely protected against a lethal challenge with virulent PRV (HB).