天然气生成的化学机理及其应用

天然气生成的化学机理是判别其成因类型的基本要素之一。本文概述了各种天然气生成模式中的主要化学过程，对台湾海峡地区的气源模式进行了讨论，为天然气的类型判别提供依据。

Down-regulation of Wnt Antagonist,SFRP1 in Colorectal Tumorigenesis

OBJECTIVE To assess the functional change of SFRP1 （secreted frizzled-related protein1）, in colorectal tumorigenesis. METHODS Immunohistochemical investigation and the semiquantitative reverse transcription-polymerase chain reaction （RT-PCR） were used to assess the expression of SFRP1, β-catenin （β-cat） and E-caderin （E-cad） in matched samples of normal colorectal mucosa, adenomas and cancers. RESULTS SFRP1 mRNA expression was down-regulated in the neoplasms, and abnormal expressions of β-cat and E-cad were found in colorectal adenomas and colorectal cancers. CONCLUSION Down-regulation of SFRP1 observed is consistent with its acting as a tumor suppressor gene in colorectal tumorigenesis.

Effective siRNA targets screening for human telomerase reverse transcriptase

AIM: To study the inhibitory effects of siRNAs targeting different hTERT sequences and to screen the effective siRNA sequence.METHODS: Five double-stranded siRNAs targeting coding and non-coding regions of hTERT gene were designed and synthesized by T7 transcription system in vitro. siRNA4sequence was screened by full length gene targeting technique and the rest of the siRNA sequences were selected randomly. After being purified by ethanol precipitation, the siRNAs were transfected to the human hepatocellular carcinoma cell (HepG2) by Lipofectamine 2000TM. At 48-72 h after siRNAs transfection, MTT assay,RT-PCR and Western-blot were applied to evaluate the effects of siRNAs on cell growth, mRNA and protein expression level of hTERT gene, respectively.RESULTS: Compared to the control cells, the cells treated with the five double-stranded siRNAs exhibited different degrees of inhibition of cell proliferation in a dose-dependent manner. siRNA2 and siRNA4, exhibited obvious effects of inhibiting hTERT mRNA and protein expression in HepG2cells.CONCLUSION: siRNAs targeting different hTERT sequences have significantly various inhibitory effects on hTERT gene expression. The siRNA sequence screened by full length gene targeting technique has comparable inhibitory effect with the rest siRNA sequences screened by random selection, suggesting that siRNAs and antisense oligonucleic acids may have the same effective target sites. Compared with chemical synthesis method,synthesizing double-stranded siRNA by T7 transcription system in vitro is a rapid, simple, and inexpensive method suitable for screening high-effect siRNA targeting site for specific gene.

The research on the thermal destruction of environment and controlling techniques of the No.4 outcrops fire in Haibaoqing

The coal fire is one of very serious disasters in natural, not only amount of coal resources was burned and some ecological environment problems such as ground subsidence, acid rain, pollution and vegetation died were caused serious. The No.4 coal seam outcrops fire in Haibaoqing was take as research object, based on the existing theory of mechanism and characteristics of coal outcrop fires, a new fire-fighting composite gel is applicated which fits in with extinguishment of outcrop coal fires well. The technology has many advantages in extinguishing coal fires including isolating the coal from oxygen and lowering the temperature of the high-temperature coal and rock. The structure and chemical composition as well as fires-fighting properties of the composite gel is analyzed profoundly, as a result, reduce and stop the environment destruction caused by the coal fire.

Ferronickel preparation using Ni-Fe co-deposition process

Nucleation mechanism and technological process for Ni-Fe co-deposition with a relatively high Fe^(2+)concentration surrounded were described,and the effects of Fe^(2+) concentration,solution pH,temperature,and sodium dodecyl sulfonate concentration were investigated.Electrochemical experiments demonstrate that iron's electrodeposition plays a leading role in the Ni-Fe co-deposition process,and the co-deposition nucleation mechanism accords with a progressive nucleation.Temperature increase does favor in increasing nickel content in the ferronickel(Ni-Fe co-deposition products),while Fe^(2+) concentration increase does not.When solution pH is higher than 3.5,nickel content in the ferronickel decreases with pH because of the hydrolysis of Fe^(2+).With the current density of 180 A/m^2,Na_2SO_4 concentration of 100 g/L and Ni^(2+) concentration of 60 g/L,a smooth ferronickel deposit containing 96.21% Ni can be obtained under the conditions of temperature of 60 °C,Fe^(2+) concentration of 0.3 g/L,solution pH of 3 and sodium dodecyl sulfonate concentration of 40 mg/L.

Chemical comparison of Semen Euphorbiae and Semen Euphorbiae Pulveratum by UPLC-Q-TOF/MS coupled with multivariate statistical techniques

In the present study,we aimed to assess the chemical composition changes of Semen Euphorbiae(SE)and Semen Euphorbiae Pulveratum(SEP)by UPLC-Q-TOF/MS and multivariate statistical methods.The UPLC-Q-TOF/MS method and SIMCA-P software were used to analyze the changes of chemical components of SE and SEP based on PCA and PLS-DA multivariate statistical methods.A"component-target-disease"network model was constructed by Intelligent Platform for Life Sciences of traditional Chinese medicine(TCM)to predict potential related diseases.The differences of chemical composition were significant between SE and SEP.Under positive ion mode,the amounts of Euphorbia factor L2,L3,L7a,L8,L9 and lathyrol were obviously decreased after processing.Under negative ion mode,the amounts of aesculetin,bisaesculetin,ingenol and cetylic acid were increased obviously,while Euphorbia factor L1,L4 and L5 were decreased obviously after processing,and the components of euphobiasteroid,aesculetin,lathyrol and linoleic acid among the 14 differentiated compounds were closely related to the SE-related diseases through the"component-target-disease"network model.UPLC-Q-TOF/MS technology in combination with multivariate statistical methods had certain advantages in studying the complex changes of chemical composition before and after manufacturing pulveratum of SE.It provided a basis for clarifying the toxicity-attenuated mechanisms of SE manufacturing pulveratum,and laid the foundation for its further development and utilization.

A new insight into electrochemical detection of eugenol by hierarchical sheaf-like mesoporous NiCo2O4

NiCo2O4 nanosheets with sheaf-like nanostructure morphologies have been synthesized by a facile one-step hydrothermal reaction followed by annealing treatment. Impressively, the NiCo2O4 nanosheets exhibit rapid detection of eugenol. The linear range of detection is from 1-500μM, and the limit of detection is 5.4 μM. The NiCo2O4 modified electrode demonstrated high sensitivity, good repeatability and reproducibility, and long-term stability （7% decrease in response over 30 days）. Based on this work, an electrochemical reaction mechanism for eugenol oxidation was proposed, and in addition, the NiCo2O4 modified electrode was successfully employed for the analysis of eugenol in medicative balm samples. Recovery values for eugenol in medicative balm samples were in the range 98.7%-105.5%.

Reaction mechanism and chemoselectivity of gold(Ⅰ)-catalyzed cycloaddition of 1-(1-alkynyl) cyclopropyl ketones with nucleophiles to yield substituted furans

The mechanisms of gold（I）-catalyzed cycloaddition of 1-（1-alkynyl） cyclopropyl ketones with nucleophiles have been investi- gated using density functional theory calculations at the B3LYP/6-31G （d, p） level of theory. A polarizable continuum model （PCM） has been established in order to evaluate the effects of solvents on the reactions. The results of the calculations indicate that the first step of the catalytic cycle is the cyclization of the carbonyl oxygen onto the triple bond which forms a new and stable resonance structure of an oxonium ion and a carbocation intermediate. The subsequent ring expansion step results in the formation of the final product and regeneration of the catalyst. Furthermore, the regioselectivity and effect of substituents has been discussed, including an analysis of energy, bond length, and natural bond orbital （NBO） charge distributions in the rate-determining step. Our computational results are consistent with earlier experimental observations.