Carbon monoxide adsorption on molybdenum phosphides: Fourier transform infrared spectroscopic and density functional theory studies

Molybdenum phosphide (MoP) and supported molybdenum phosphide (MoP/gamma-Al2O3) have been prepared by the temperature-programmed reduction method. The surface sites of the MoP/gamma-Al2O3 catalyst were characterized by carbon monoxide (CO) adsorption with in situ Fourier transform infrared (FT-IR) spectroscopy. A characteristic IR band at 2037 cm(-1) was observed on the MoP/gamma-Al2O3 that was reduced at 973 K. This band is attributed to linearly adsorbed CO on Mo atoms of the MoP surface and is similar to IR bands at 2040-2060 cm(-1), which correspond to CO that has been adsorbed on some noble metals, such as platinum, palladium, and rhodium. Density functional calculations of the structure of molybdenum phosphides, as well as CO chemisorption on the MoP(001) surface, have also been studied on periodic surface models, using the generalized gradient approximation (GGA) for the exchange-correlation functional. The results show that the chemisorption of CO on MoP occurred mainly on top of molybdenum, because the bonding of CO requires a localized mininum potential energy. The adsorption energy obtained is DeltaH(ads) approximate to -2.18 eV, and the vibrational frequency of CO is 2047 cm-1, which is in good agreement with the IR result of CO chernisorption on MoP/gamma-Al2O3.

A single-strand conformation polymorphism method by capillary electrophoresis with laser-induced fluorescence for detection of the T1151A mutation in hMLH1 gene

Mutation of hMLH1 gene plays an important role in human tumorigenesis. A highly sensitive single-strand conformation polymorphism (SSCP) method for detection of the T1151A mutation in exon 12 of the hMLH1 gene was for the first time developed employing laser-induced fluorescence capillary electrophoresis (LIF-CE). Effects of the concentration of linear polyacrylamide solution, running temperature, running voltage and the addition of glycerol on SSCP analysis were investigated, and the optimum separation conditions were defined. Thirty colorectal cancer patients and eight lung cancer patients were screened and the T1151A mutation was found in four of them. Based on CE-sequencing the mutation was further confirmed. To our knowledge, this is for the first time that the T1151A mutation is found in lung cancer. Our method is simple, rapid, and highly sensitive and is well suited to the analysis of large numbers of clinical samples.

Soil microbial community analysis using terminal restriction fragment length polymorphisms

Terminal restriction fragment length polymorphism (T-RFLP) analysis is a polymerase chain reaction (PCR)-fingerprinting method that is commonly used for comparative microbial community analysis. The method can be used to analyze communities of bacteria, archaea, fungi, other phylogenetic groups or subgroups, as well as functional genes. The method is rapid, highly reproducible, and often yields a higher number of operational taxonomic units than other, commonly used PCR-fingerprinting methods. Sizing of terminal restriction fragments (T-RFs) can now be done using capillary sequencing technology allowing samples contained in 96- or 384-well plates to be sized in an overnight run. Many multivariate statistical approaches have been used to interpret and compare T-RFLP fingerprints derived from different communities. Detrended correspondence analysis and the additive main effects with multiplicative interaction model are particularly useful for revealing trends in T-RFLP data. Due to biases inherent in the method, linking the size of T-RFs derived from complex communities to existing sequence databases to infer their taxonomic position is not very robust. This approach has been used successfully, however, to identify and follow the dynamics of members within very simple or model communities. The T-RFLP approach has been used successfully to analyze the composition of microbial communities in soil, water, marine, and lacustrine sediments, biofilms, feces, in and on plant tissues, and in the digestive tracts of insects and mammals. The T-RFLP method is a user-friendly molecular approach to microbial community analysis that is adding significant information to studies of microbial populations in many environments.

Stable Isotope Probing:Linking Functional Activity to Specific Members of Microbial Communities

Linking organisms or groups of organisms to specific functions within natural environments is a fundamental challenge in microbial ecology. Advances in technology for manipulating and analyzing nucleic acids have made it possible to characterize the members of microbial communities without the intervention of laboratory culturing. Results from such studies have shown that the vast majority of soil organisms have never been cultured, highlighting the risks of culture-based approaches in community analysis. The development of culture-independent techniques for following the flow of substrates through microbial communities therefore represents an important advance. These techniques, collectively known as stable isotope probing (SIP), involve introducing a stable isotope-labeled substrate into a microbial community and following the fate of the substrate by extracting diagnostic molecular species such as fatty acids and nucleic acids from the community and determining which specific molecules have incorporated the isotope. The molecules in which the isotope label appears provide identifying information about the organism that incorporated the substrate. Stable isotope probing allows direct observations of substrate assimilation in minimally disturbed communities, and thus represents an exciting new tool for linking microbial identity and function. The use of lipids or nucleic acids as the diagnostic molecule brings different strengths and weaknesses to the experimental approach, and necessitates the use of significantly different instrumentation and analytical techniques. This short review provides an overview of the lipid and nucleic acid approaches, discusses their strengths and weaknesses, gives examples of applications in various settings, and looks at prospects for the future of SIP technology.

functional monomers and polymers.CXXXVI.effect of metal ions on the interaction of synthetic nucleic acid analogs

The effect of metal ions on the conformation of thymine-containing poly-D-lysine was studied by CD spectra in aqueous solution. Of the metal ions studied,only copper(Ⅱ)ion affected the conformation of mucleic acid analogs .copper(Ⅱ)ion also affected the specifically interacting system made up of thymine-containing poly-D-lysine and polyadenylic acid.

Urban functional structure characteristics and transformation in China

The paper analyzes urban functional structure characteristics of Chinese cities in 1996 using the Nelson method. The manufacturing employment percentage is much higher in metropolitan areas but is decreasing from 1989 to 1996. On the other hand, the weight of science, education, culture, hygiene, finance, insurance and real estate increases. The employment structure changes dramatically. Although the urbanization level of China is lower than that of the USA in 1955, the frequency distribution curve of urban functions is similar. The construction, transportation, commerce, finance, insurance, real estate, science, education, culture, hygiene and administration curves are normal. The mining employment converges on minor cities and the distribution is not normal. The urban function has changed with urban scale. The bigger the cities are, the smaller the manufacture, mining and construction employment weights, and the larger are the science, education, finance, insurance, real estate and administration weights. Commerce and transportation are distributed evenly and the difference is less. From the comparison in three zones of China, the employment percentage of manufacture, finance, insurance and real estate is higher in eastern coastal areas, while the employment percentage of science, education, administration is higher in western areas. (C) 2002 Elsevier Science Ltd. All rights reserved.

Layer-by-layer assembly of functional silica and Au nanoparticles for fabricating electrogenerated chemiluminescence sensor

We described the use of silica nanoparticles as building blocks for the immobilization of electrogenerated chemiluminescence (ECL) reagent Ru(bpy)3" and the fabrication of layer-by-layer assembly film by alternating the deposition of the Ru(bpy)3 2'-doped silica nanoparticles and Au nanoparticles.

Thermoplastic Elastomers Based on Compatibilized Poly(butylene terephthalate) Blends: Effect of Functional Groups and Dynamic Curing

Two sets of graft copolymers were prepared by grafting glycidyl methacrylate (GMA) or ally] (3-isocyanate-4-tolyl) carbamate (TAI) onto ethylene/propylene/diene terpolymer (EPDM) in an internal mixer. These graft copolymers were used as the compatibilizer to prepare the thermoplastic elastomers (TPEs) containing 50 wt%, of poly(butylene terephthalate), PBT, 30 wt% of compatibilizer, and 20 wt% of nitrile-butadiene rubber, NBR. The indirect, two-step mixer process was chosen for dynamic curing.