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result(s) for
"化学研究"
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Geochemical studies on the source region of Asian dust
2011
The North China and the neighbouring Mongolia in Asian Interior is characterized by extremely dry climate, resulted in one of the world's major dust emission centres. Deciphering the source region of Asian dust is critical for revealing the mechanism of the dust production, interpreting the paleo-environrnental records of eolian deposits, predicting the overall environmental effects of dust, and setting the strategies for the control of contemporary dust storms. This paper summarizes the geochemical methods applied to the source tracing of Asian dust. Nd-Sr isotopes were the most extensively studied source tracer of Asian dust and have been successfully applied in many cases. Geochemistry of detrital monomineral shows great theoretical advantages in source tracing and deserves further studies. The short-range transportation of Chinese loess with direction similar to that of the prevailing near surface wind is revealed. Source tracing also shows that the Asian dust has two ultimate material sources from the northern margin of the Tibetan Plateau and the Central Asian Orogen, which confirms the importance of mountain processes in the production of silt eolian particles. Based on the recent progresses on the source tracing of Asian dust, discussions are expanded on the natural background of Asian dust storms and potential anthropogenic influence, the materials evolution of the source regions of Asian dust and its relationships with climate changes and Tibetan uplift, and the role of Tibetan uplift in the Asian dust system.
Journal Article
A Review of Atmospheric Chemistry Research in China: Photochemical Smog, Haze Pollution, and Gas-Aerosol Interactions
2012
In this paper we present a review of atmospheric chemistry research in China over the period 2006-2010, focusing on tropospheric ozone, aerosol chemistry, and the interactions between trace gases and aerosols in the polluted areas of China. Over the past decade, China has suffered severe photochemical smog and haze pollution, especially in North China, the Yangtze River Delta, and the Pearl River Delta. Much scientific work on atmospheric chemistry and physics has been done to address this large-scale, complex environmental problem. Intensive field experiments, satellite data analyses, and model simulations have shown that air pollution is significantly changing the chemical and physical characters of the natural atmosphere over these parts of China. In addition to strong emissions of primary pollutants, photochemical and heterogeneous reactions play key roles in the formation of complex pollution. More in-depth research is recommended to reveal the formation mechanism of photochemical smog and haze pollution and their climatic effects at the urban, regional, and global scales.
Journal Article
Challenges and perspectives of combustion chemistry research
by
Wenhao Yuan;Yuyang Li;Fei Qi
in
Chemistry
,
Chemistry and Materials Science
,
Chemistry/Food Science
2017
In the past decades, combustion chemistry research grew rapidly due to the development of combustion diagnostic methods, quantum chemistry methods, kinetic theory, and computational techniques. A lot of kinetic models have been developed for fuels from hydrogen to transportation fuel surrogates. Besides, multi-scale research method has been widely adopted to develop comprehensive models, which are expected to cover combustion conditions in real combustion devices. However, critical gaps still remain between the laboratory research and real engine application due to the insufficient research work on high pressure and low temperature combustion chemistry. Besides, there is also a great need of predictive pollutant formation model. Further development of combustion chemistry research depends on a closer interaction of combustion diagnostics, theoretical calculation and kinetic model development. This paper summarizes the recent progress in combustion chemistry research briefly and outlines the challenges and perspectives.
Journal Article
Urea-bridged diferrocene: structural, electrochemical, and spectroelectrochemical studies
2015
Urea-bridged diferrocene derivatives N,N"-diferrocenylurea(1) and N,N"-dimethyl-N,N"-diferrocenylurea(2) were prepared and characterized. Single-crystal X-ray analysis shows that Compound 1 has a trans-trans linear conformation whereas Compound 2 has a trans-cis conformation. Both compounds display two consecutive redox couples with, respectively, E1/2 of +0.29 and +0.42 V vs. Ag/Ag Cl for 1 and +0.31 and +0.50 V for 2. Spectroelectrochemical studies show the presence of distinct intervalence charge transfer(IVCT) transitions for the one-electron-oxidized mixed-valent Compound 1+, with an estimated electronic coupling parameter of 190 cm^-1. By contrast, the one-electron-oxidized Compound 2+ shows much weaker IVCT transitions.
Journal Article
A Comparative Geochemistry Study of Several Oil Shale-Bearing Intervals in the Paleogene Huadian Formation, Huadian Basin, Northeast China
by
Yu Song Zhaojun Liu Pingchang Sun Qingtao Meng Rong Liu
in
Anoxia
,
Aridity
,
Atmospheric precipitations
2017
The Huadian Basin is an oil shale-bearing basin located in northeastern China. Thirteen oil shale layers deposited in this basin, and the characteristics of oil shale are different among these oil shale layers. Based on the core observation and microscope identification, using the organic and inor- ganic data from borehole HD3 and outcrops, the formation conditions of different grade oil shale have been evaluated. Based on measuring oil yield (OY in short) of an oil shale to determine its grade, this paper classifies the oil shale as high grade (OY〉10%), medium grade (10%〉OY〉5%) and low grade (5%〉OY〉3.5%). The high grade oil shale is mainly in brown or dark brown, and the bulk density ranges from 1.59 to 1.81 g/cm3. The results of X-ray diffraction indicate the content of carbonate min- erals is 28.0%. The HI (hydrogen index)-Tmax, HI-OI (oxygen index) and S2-TOC (total organic carbon) diagrams indicate the kerogen types are I and II1. The high grade oil shale generally formed in the rela- tively arid paleoclimate, deposited in the brackish water, dysoxic environment, when the bioprodctivity is extremely high, and the information is mainly from the inorganic parameters diagrams of chemical index of alteration (CIA), Sr/Ba and V/(V+Ni). The medium grade oil shale mainly shows grey-black or black-brown color and the bulk density ranges from 1.87 to 2.08 g/cm^3. The average content of carbon- ate minerals is 16.4%, far less than high grade oil shale and the kerogen type is mainly IIm. The inor- ganic parameters diagrams reflect the medium grade oil shale generally formed in the less humid pa- leoclimate, deposited in the brackish water, dysoxic to anoxic environment, when the bioproductivity is medium. The color of low grade oil shale is major in grey-black or dark grey and the bulk density ranges from 2.00 to 2.15 g/cm^3. The average content of carbonate minerals is sharply decreased and the kerogen type is mainly II1. The inorganic parameters diagrams indicate the low grade oil shale gener- ally formed in the relatively humid paleoclimate, deposited in the freshwater to brackish water, anoxic environment, when the bioproductivity is relatively low. Comprehensive study suggest the increasing precipitation caused by a relatively humid paleoclimate resulted in decreasing oxygen concentration and salinity in the bottom water, restrained the salinity stratification, and tended to form the low grade oil shale. The strong evaporation leading to relatively arid paleoclimate resulted in increasing oxygen concentration and salinity in the bottom water, and promoted the salinity stratification. The area with well preservation conditions caused by the relative high sedimentary rate and salinity stratification are favorable to high grade oil shale deposit. In summary, the bioproductivity and the paleoclimate are the main factors controlling the oil shale grade in the Huadian Basin, when the bioproductivity is relatively high and the paleoclimate is relatively arid, it is prone to form the high grade oil shale. However the low grade oil shale developed in the low bioproductivity and relatively humid paleoclimate.
Journal Article
Immunohistochemical evaluation of vitamin D receptor(VDR) expression in cutaneous melanoma tissues and four VDR gene polymorphisms
by
Francesco La Marra Giuseppe Stinco Cinzia Buligan Giovanni Chiriacò Diego Serraino Carla Di Loreto Sabina Cauci
in
免疫组织
,
化学研究
,
基因多态性
2017
Objective:Vitamin D receptor(VDR)mediates vitamin D activity.We examined whether VDR expression in excised melanoma tissues is associated with VDR gene(VDR)polymorphisms.Methods:We evaluated VDR protein expression(by monoclonal antibody immunostaining),melanoma characteristics,and carriage of VDR-Fok I-rs2228570(C〉T),VDR-Bsm I-rs1544410(G〉A),VDR-ApaI-rs7975232(T〉G),and VDR-TaqI-rs731236(T〉C)polymorphisms(by restriction fragment length polymorphism).Absence or presence of restriction site was denoted by a capital or lower letter,respectively:"F"and"f"for Fok I,"B"and"b"for Bsm I,"A"and"a"for ApaI,and "T"and"t"for TaqI endonuclease.Seventy-four Italian cutaneous primary melanomas(52.1±12.7 years old)were studied;51.4% were stage Ⅰ,21.6% stage Ⅱ ,13.5% stage Ⅲ,and 13.5% stage Ⅳ melanomas.VDR expression was categorized as follows:100% positive vs.〈100%;over the median 20%(high VDR expression)vs.≤20%(low VDR expression);absence vs.presence of VDR-expressing cells.Results:Stage I melanomas,Breslow thickness of〈1.00 mm,level II Clark invasion,Aa heterozygous genotype,and AaTT combined genotype were more frequent in melanomas with high vs.low VDR expression.Combined genotypes BbAA,bbAa,AATt,BbAATt,and bbAaTT were more frequent in 100%vs.〈100%VDR-expressing cells.Combined genotype AATT was more frequent in melanomas lacking VDR expression(odds ratio=14.5;P=0.025).VDR expression was not associated with metastasis,ulceration,mitosis〉1,regression,tumor-infiltrating lymphocytes,tumoral infiltration of vascular tissues,additional skin and non-skin cancers,and melanoma familiarity.Conclusions:We highlighted that VDR polymorphisms can affect VDR expression in excised melanoma cells.Low VDR expression in AATT carriers is a new finding that merits further study.VDR expression possibly poses implications for vitamin D supplementation against melanoma.VDR expression and VDR genotype may become precise medicinal tools for melanoma in the future.
Journal Article
New antiglycation and enzyme inhibitors from Parmotrema cooperi
by
M. Iqbal CHOUDHARY Meher ALI Atia-tul-WAHAB Ajmal KHAN Saima RASHEED Sajan Lal SHYAULA Atta-ur-RAHMAN
in
Bioassays
,
Chemistry
,
Chemistry and Materials Science
2011
Lichens are unique individuals which have been widely used in traditional medicines. This study was focused on the bioassayguided phytochemical investigation, and bioactivity evaluation on a lichens species, Parmotrema cooperi. This first bioassaydirected chemical study on P. cooperi has led to the isolation of ethyl heamatomate (1), atraric acid (2), ethyl orsellinate (3), orsellinic acid (4), lecanoric acid (5), gyrophoric acid (6), and licanorin (7). The structures of 1-7 were mainly elucidated from spectroscopic methods including 1D, and 2D NMR spectroscopy, and mass spectrometry. These compounds were evaluated for their antiglycation, urease, a-chymotrypsin, and β-glucoronidase inhibitory activities. Few of the phenolic compounds showed significant, while most of them showed good inhibition of protein glycation, and urease activities.
Journal Article
Using Geochemistry of Rare Earth Elements to Indicate Sediment Provenance of Sand Ridges in Southwestern Yellow Sea
2017
The Jianggang Harbour-centered radial sand ridge(RSR) is the largest sand body in the Yellow Sea. Its formation and evolution are of interest for scientists of various fields; however, the sediment provenance is uncertain. In this study, rare earth element(REE) geochemical compositions of the RSR sediments together with their potential sources are investigated to identify the provenance of the RSR sediments. The typical parameters((La/Yb)N,(La/Sm)N and(Gd/Yb)_N) as well as the upper continental crust-normalized patterns of REEs can only be associated with source rocks, and thus can be used as effective tracers for the origin and sources of sediments. However, the REE contents of sediments are affected by many factors, such as particle sorting and chemical weathering. Onshore RSR sediments are different in REE geochemical composition from offshore RSR sediments to some extent, suggesting that not all of the offshore RSR sediments have the same sources as the onshore RSR sediments. Meanwhile, the sediments adjacent to the northeast of Cheju Island and at Lian Island near the Lianyun Harbour were not the source of the RSR sediments due to their distinctive REE patterns, dEu,(La/Yb)_N,(Gd/Yb)_N and(La/Sm)_N. The Korean river sediments could be dispersed to the Jiangsu Coast slightly impacting the fine fractions of the RSR sediments, particularly the offshore RSR sediments. Additionally, geochemical comparisons show that the modern Yellow River was responsible for the onshore RSR sediments, whereas the sediment loads from the Yangtze River could serve as a major contributor to the RSR, particularly the offshore RSR. In addition, the offshore RSR could also be partly fed by an unknown source due to some high values of(La/Yb)_N,(La/Sm)_N and La contents differing from those of the Chinese and Korean river sediments.
Journal Article
Celebrating the 60th Anniversary of Institute of Chemistry, Chinese Academy of Sciences
2016
Institute of Chemistry, Chinese Academy of Sciences (ICCAS) was established in 1956. ICCAS is a multi- disciplinary research institute dedicated to the basic re- search in broad fields of chemical sciences, and to the key development of the innovative high-technology aiming at the imperative national needs and important strategic tar- gets, as well as to the collaborative high-technology appli- cations and transfers. With the development of 60 years, ICCAS has become one of the leading chemistry institutions in China with high international visibility.
Journal Article
A hydrochemical study of the Hammam Righa geothermal waters in north-central Algeria
by
Bouchareb-Haouchine, Fatima Zohra
,
Belhai, Mohamed
,
Nishijima, Jun
in
Chemicals
,
Cold springs
,
Dolomite
2016
This study focuses on the hydrochemical characteristics of 47 water samples collected from thermal and cold springs that emerge from the Hammam Righa geothermal field, located in north-central Algeria. The aquifer that feeds these springs is mainly situated in the deeply fractured Jurassic limestone and dolomite of the Zaccar Mount. Measured discharge temperatures of the cold waters range from 16.0 to 26.5 °C and the hot waters from 32.1 to 68.2 °C. All waters exhibited a near-neutral pH of 6.0–7.6. The thermal waters had a high total dissolved solids (TDS) content of up to 2527 mg/l, while the TDS for cold waters was 659.0–852.0 mg/l. Chemical analyses suggest that two main types of water exist: hot waters in the upflow area of the Ca–Na–SO
4
type (Hammam Righa) and cold waters in the recharge zone of the Ca–Na–HCO
3
type (Zaccar Mount). Reservoir temperatures were estimated using silica geothermometers and fluid/mineral equilibria at 78, 92, and 95 °C for HR4, HR2, and HR1, respectively. Stable isotopic analyses of the δ
18
O and δD composition of the waters suggest that the thermal waters of Hammam Righa are of meteoric origin. We conclude that meteoric recharge infiltrates through the fractured dolomitic limestones of the Zaccar Mount and is conductively heated at a depth of 2.1–2.2 km. The hot waters then interact at depth with Triassic evaporites located in the hydrothermal conduit (fault), giving rise to the Ca–Na–SO
4
water type. As they ascend to the surface, the thermal waters mix with shallower Mg-rich groundwater, resulting in waters that plot in the immature water field in the Na–K–Mg diagram. The mixing trend between cold groundwaters from the recharge zone area (Zaccar Mount) and hot waters in the upflow area (Hammam Righa) is apparent via a chloride-enthalpy diagram that shows a mixing ratio of 22.6 < R < 29.2 %. We summarize these results with a geothermal conceptual model of the Hammam Righa geothermal field.
Journal Article