检索结果-南通市图书馆

Acta Geologica Sinica(English Edition) 2021年第6期95卷 2087-2099页

作者： Osama r.SALLAM Abdalla S.ALSHAMI Abd Elhadi A.ABBAS E.GUIBAL Nuclear Materials Authority CairoEgypt Institut Mines Telecom-Mines Ales Centre des Materiaux des Mines d’AlesUniversityMontpellierFrance

The Lower Carboniferous sediments at Wadi Abu El Mogheirat consist of four stratigraphic formations, from base upwards: Um Bogma, El Hashash, Magharet El Maiah and Abu Zarab formations. The most-concentrated radioactive anomalies at Wadi Abu El Mogheirat are in the middle member of the Um Bogma Formation. The gibbsitic marl in this formation shows the highest uranium contents(around 710 ppm). Gibbsitic marl and black gibbsite of the middle Um Bogma Formation show higher enrichment in Co, Cu, Mn, Ni, Pb, Zn, U, V, Ce and Th. Black gibbsite contains the highest total rare earth elements concentration, especially in terms of LrEEs, while gibbsitic marl contains the highest content of HrEEs. Anomalous contents of gold at Wadi Abu El Mogheirat are recorded for the first time in the gibbsitic marl(content: 10.4 ppm), black gibbsite(2.8 ppm) of the middle member of the Um Bogma Formation and in the siltstones of the El Hashash Formation(0.6 ppm). Gibbsitic marl shows the presence of uranothorite, celestite, zircon, atacamite, barite, xenotime and rutile. These characteristic demonstrate that the middle member of the Um Bogma Formation constitutes a potential source for gold. This conclusion is reinforced by the potential to exploit other metals such as Co, Cu, Mn, Ni, Pb, Zn, U, V, Th and Ce as by-products.

关键词： gibbsite rare earth elements Um Bogma

In vitro Safety Evaluation and Anticlastogenic Effect of BacoMind^(TM) on Human Lymphocytes

在线全文

学校读者我要写书评

暂无评论

Biomedical and Environmental Sciences 2008年第1期21卷 7-23页

作者： DIPANWITA DUTTA DEB PrEETI KAPOOr r. P. DIGHE r. PADMAJA M. S. ANAND P. D'SOUZA M. DEEPAK B. MUrALI AMIT AGArWAL Natural remedies Pvt. Ltd 19 K. M. Stone Hosur Road Plot No. 5B Veerasandra Indl. Area Bangalore 560100 India

Objective BacoMind^TM （BM） is a standardized extract of Bacopa monnieri, which belongs to the family Scrophulariaceae and is a creeping annual plant found throughout the Indian subcontinent. It has been used by Ayurvedic medicinal practitioners in India for almost 3000 years and is classified as a medharasayana, a substance which improves memory and intellect. With the widespread traditional use as well as scientific validation of Bacopa monnieri for nootropic activity, a bioactive-rich unique phytochemical composition-BacoMind^TM was developed from B. monnieri for use as a cognition and memory enhancing agent. The present study aimed to investigate the in vitro toxicity of this formulation of BacoMind^TM on human lymphocytes and to rule out its possible contribution to mutagenicity. Methods In the present investigation the active ingredients present in BM were identified and quantified by high performance liquid chromatography （HPLC） and high performance thin-layer chromatography （HPTLC）. Antioxidant and anticlastogenic properties of BM were studied in vitro with and without metabolic activation. Doses of BM were chosen on the basis of mitotic index （MI） and cytokinesis-block proliferation index （CBPI）. Clastogenicity assays were performed at 31.2 μg/mL, 62.5 μg/mL, and 125 μg/mL, while the Salmonella reverse mutation assay （Ames test） was performed at doses of 61.72, 185.18, 555.55, 1666.67, and 5000.00 μg/plate. results HPLC and HPTLC analysis of BM revealed the presence of bacoside A3. bacopaside Ⅰ, bacopaside Ⅱ, jujubogenin isomer of bacopasaponin C, bacosine, luteolin, apigenin, bacosine, and β-sitosterol D glucoside. BM demonstrated significant antioxidant activity. The number of chromosomal aberrations and the frequency of micronuclei induced by BM were not statistically significant up to a dose of 62.5 μg/mL. A subsequent dose of 125 μg/mL prior to metabolic activation induced mild clastogenicity, but it was found to be biologically insignificant as this ef

关键词： BacoMind^TM Cytotoxicity Chromosomal aberration Ames test Micronucleus, Clastogens Antioxidant High performance liquid chromatography High performance thin-layer chromatography (HPTLC)

Process Engineering Evaluation of Modern High Performance Packings for Mass Transfer Apparatus

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2013年第7期21卷 714-723页

作者： BILLET r SCHULTES M. Institute for Thermo- and Fluid Dynamics Universiaitsstrasse 150 44780 Ruhr University of Bochum Germany Mundenheimerstrasse 100 67061-Ludwigshafen Germany

Modem packing technology is presented in terms of correlations and criteria for an extensive evaluation of up-to-date packing design used in current mass transfer operations. The corresponding basic information covers the process engineering aspects, e.g. volumetric effectiveness and optimum geometry of the packing, and the techno-economic aspects, e.g. when selecting a packing adopted in practice for a certain application task. The correlations required for this investigation are derived and evaluated on the basis of a comprehensive experimental re- search by testing and comparison of modem packings, such as raschig Super-rings and reference packings. The results thus obtained are correlated and presented in graphic presentation of diagrams, figures and tables.

关键词： throughput mass transfer effective surface specific cost of packing "

Synthesis of SWNTs over nanoporous Co-Mo/MgO and using as a catalyst support for selective hydrogenation of syngas to hydrocarbon

在线全文

学校读者我要写书评

暂无评论

Journal of Natural Gas Chemistry 2010年第5期19卷 548-551页

作者： A.M.rashidi A.Karimi H.r.Bozorgzadeh K.Kashefi M.Zare Nanotechnology research Center Research Institute of petroleum industry (RIPI)West Blvd.Azadi Sport ComplexP.O.Box: 14665-1998TehranIran

Single-wall carbon nanotubes （SWNTs） with high surface area were synthesized over nanoporous Co-Mo/MgO by a chemical vapor deposition （CVD） method. The SWNTs were used as catalyst support for selective hydrogenation of syngas to hydrocarbons. Here an extensive study of Fischer-Tropsch synthesis （FTS） on CNT-supported cobalt catalysts with different amounts of cobalt loading up to 40 wt% is reported. The catalysts were characterized by different methods including N2 adsorption-desorption, X-ray diffraction, hydrogen chemisorption, inductively coupled plasma （ICP） and temperature-programmed reduction. Enhancement of the reducibility of Co3O4 to CoO, CoO to Co° and small cobalt oxide particles, dispersion of the cobalt, and activity and selectivity of FTS were investigated and compared with a conventional support. The CNT supported catalysts achieve a high dispersion and high loading of the active metal, cobalt in particular, so that the bulk formation of cobalt metal, which tends to occur in conventional support, can be avoided. The results showed that the specific activity of CNT supported catalysts increase significantly （there is a two fold increase in CO Conversion per gram of the active metal） with respect to the conventional supported catalyst.

关键词： CNT SWNTs Fiscber-Tropsch cobalt reducibility activity C5+ selectivity

Synthesis and Characterization of Zinc Succinate, Zn(C4H4O4)

在线全文

学校读者我要写书评

暂无评论

Chemical research in Chinese Universities 2001年第1期17卷 20-25页

作者： ZHENG Yue qing ** (Institute for Solid State Chemistry, Ningbo University, Ningbo 315211, P. r. China) Ningbo Univ Inst Solid State Chem Ningbo 315211 Peoples R China Max Planck Inst Festkorperforsch D-70569 Stuttgart Germany

PETErS Karl and von SCHNErING Hans Georg (Max Planck Institute für Festkrperforschung, D 70569 Stuttgart, Germany)Zn(C 4H 4O 4) prepared by dissolving 0.483 g (1.41 mol) of Zn 3(OH) 4CO 3·H 2O and 0.5 g (4.23 mol) of C 4H 6O 4 in 50 mL of H 2O followed by slow evaporation at room temperature crystallizes in the monoclinic space group C 2 with the cell parameters a =0.757 9(1) nm, b =0.597 6(1) nm , c =0.626 5(1) nm, β =108.45(1)°, V =0.269 17(7) nm 3, D x=2.239 \{g/cm 3\}, Z =2 and the final r(F o)=0.039 and wr(F o 2)=0.088 for 396 reflections [ F o 2≥2 σ(F o 2)]. In the crystal structure unit, each Zn is tetrahedrally coordinated by four O atoms from four (C 4H 4O 4) 2- anions, each of which, in turn, bridges four Zn atoms to build up a 3D \{\} 3 ∞[Zn(C 4H 4O 4) 4/4 ] network. The thermal analyses indicate that Zn(C 4H 4O 4) is stable below 420 ℃.

关键词： Synthesis Zinc succinate Crystal structure Thermal decomposition

Optimal design study of high order FIr digital filters based on neural network algorithm

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2004年第2期15卷 115-119,130页

作者： Wang Xiaohua & He YigangCollege of Electrical and Information Engineering, Hunan University, Changsha 410082, P. r. China College of Electrical and Information Engineering, Changsha University of Science and Technology,Changsha 410077, P. r. China College of Electrical and Information Engineering Hunan University Changsha 410082 P. R. China College of Electrical and Information Engineering Changsha University of Science and Technology Changsha 410077 P. R. China

An optimal design approach of high order FIr digital filter is developed based on the algorithm of neural networks with cosine basis function . The main idea is to minimize the sum of the square errors between the amplitude response of the desired FIr filter and that of the designed by training the weights of neural networks, then obtains the impulse response of FIr digital filter . The convergence theorem of the neural networks algorithm is presented and proved, and the optimal design method is introduced by designing four kinds of FIr digital filters , i.e., low-pass, high-pass, bandpass , and band-stop FIr digital filter. The results of the amplitude responses show that attenuation in stop-bands is more than 60 dB with no ripple and pulse existing in pass-bands, and cutoff frequency of passband and stop-band is easily controlled precisely .The presented optimal design approach of high order FIr digital filter is significantly effective.

关键词： high order FIr digital filters amplitude-frequency response neural network convergence theorem optimal design.

Physics, chemistry, and Hirshfeld surface analyses of gamma-irradiated thalidomide to evaluate behavior under sterilization doses

在线全文

学校读者我要写书评

暂无评论

Journal of Pharmaceutical Analysis 2018年第3期8卷 194-201页

作者： Valner A.F.S.N.Mussel Max r Ferreira Maria B.E Marques Maria I.Yoshida Mariana r.Almeida Bernardo L.rodrigues Wagner N.Mussel Departamento de Quimica ICExUniversidade Federal de Minas Gerais-UFMGAv.Antonio Carlos 662731270-901 Belo HorizonteMGBrazil CNEN-CDTN Comissao Nacional de Energia Nuclear-Centro de Desenvolvimento da Tecnologia NuclearAv.Antonio Carlos6627 Belo HorizonteMGBrazil

Thalidomide was indicated as a sedative and antiemetic and prescribed for pregnant women. Its tragic teratogenic effects culminated in withdrawal from the market. Since the discovery of its anti-angiogenic and anti-inflammatory actions, thalidomide has been used in the treatment of leprosy and multiple myeloma, which justify studies of its stability. We investigated the effects of irradiation of thalidomide up to 100 kGy （fourfold the usual sterilizing dose for pharmaceutics）. The polymorph of thalidomide was obtained in an isothermal experiment at 270℃. All samples underwent gamma irradiation for specific times. At different doses, decomposition of the pharmaceutical was not observed up to 100 kGy. The observed effect was angle turning between the phthalimide and glutarimide rings modulated by repulsion towards the carbonyl group, leading to a stable energetic configuration, as measured by the equilibrium in the torsion angle after irradiation. The thalidomide molecule has a center of symmetry, so a full turn starting from 57.3° will lead to an identical molecule. Further irradiation will start the process again. Samples irradiated at 30 and 100 kGy have more compact unit cells and a lower volume, which leads to an increase in the intermolecular hydrogen interaction within the unit cell, resulting in higher thermal stability for polymorph α.

关键词： Thalidomide Thermal stability Polymorphs Gamma irradiation Hirshfeld

TWO-GrID METHOD FOr CHArACTErISTICS FINITE-ELEment SOLUTION OF 2D NONLINEAr CONVECTION-DOMINATED DIFFUSION PrOBLEM

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2005年第11期26卷 1506-1514页

作者：秦新强School of Sciences Xi’an Jiaotong University Xi’an 710049 P.r.China School of Sciences Xi’an University of Technology Xi’an 710048 P.r.China) 马逸尘章胤 School of Sciences Xi’an Jiaotong UniversityXi’an 710049 P.R.China School of Sciences Xi’an University of TechnologyXi’an 710048 P.R.China

For two-dimension nonlinear convection diffusion equation, a two-grid method of characteristics finite-element solution was constructed. In this method the nonlinear iterations is only to execute on the coarse grid and the fine-grid solution can be obtained in a single linear step. For the nonlinear convection-dominated diffusion equation, this method can not only stabilize the numerical oscillation but also accelerate the convergence and improve the computational efficiency. The error analysis demonstrates if the mesh sizes between coarse-grid and fine-grid satisfy the certain relationship, the two-grid solution and the characteristics finite-element solution have the same order of accuracy. The numerical is more efficient than that of characteristics example confirms that the two-grid method finite-element method.

关键词： convection-diffusion equation characteristics finite-element two-grid method convergence

Alkali-thermal gasification and hydrogen generation potential of biomass

在线全文

学校读者我要写书评

暂无评论

Frontiers of Chemical Science and Engineering 2017年第3期11卷 369-378页

作者： Alexander B. Koven Shitang S. Tong ramin r. Farnood Charles Q. Jia Department of Chemical Engineering and Applied Chemistry University of Toronto Ontario M5S-3E5 Canada School of Chemistry and Chemical Engineering Wuhan University of Science and Technology Wuhan 430081 China

Generating hydrogen gas from biomass is one approach to lowering dependencies on fossil fuels for energy and chemical feedstock, as well as reducing greenhouse gas emissions. Using both equilibrium simulations and batch experiments with NaOH as a model alkaline, this study established the technical feasibility of converting various biomasses （e.g., glucose, cellulose, xylan and lignin） into H2-rich gas via catalyst-free, alkali-thermal gasification at moderate temperatures （as low as 300℃）. This process could produce more H2 with less carbon-containing gases in the product than other comparable methods. It was shown that alkali-thermal gasification follows CxHyO2 ＋ 2xNaOH ＋（x-z）H20 = （2x＋y/2-z）H2 ＋xNa2CO3, with carbonate being the solid product which is different from the one suggested in the literature. Moreover, the concept of hydrogen genera- tion potential （H2-GP）-the maximum amount of H2 that a biomass can yield, was introduced. For a given biomass CxHyO2, the H2-GP would be （2x ＋ y/2-z） moles of H2. It was demonstrated experimentally that the H2-GP was achievable by adjusting the amounts of H20 and NaOH, temperature and pressure. Keywords hydrogen generation potential, biomass, lignocellulose, alkali-thermal gasification, sodium hydroxide

关键词： hydrogen generation potential biomass lignocellulose alkali-thermal gasification sodium hydroxide

COMPArISON OF VArIOUS COrrELATION ON IrMA FOr CA19-9 AND CA50 IN THE DIGESTIVE SYSTEM TUMOUr

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 1990年第4期1卷 234-238页

作者：莫启忠 r.P.Baum A.Hertel G.Hr Shanghai College of Traditional Chinese Medicine Shanghai 200032 China Nuclear Medicine Division of radiological Centre Frankfurt University Hospital

This paper compared various correlation of IMrA for CA19-9 and CA50 in the digestive system tumour antigen, such as linearity, sensitivity, analytical range, precision as well as storage and stability and so on. And it also determined serum level of CA19- 9 and CA50 of patients with different tumours. The results showed it was well correlated to CA19- 9 and CA50 as a marker of digestive system tumour. Particularly high levels of both markers were found in patients with pancreastic colonic cancer. Therefore it is possible to obtain a higher sensitivity and acceptable specificity by combination with CA19-9 and CA50.

关键词： Tumour marker CA50 CA19- 9 IrMA Solid phase immunoassay Inter- and intraassay variance