大孔吸附树脂对大豆皂苷的吸附研究

比较了5种大孔吸附树脂对大豆皂苷的吸附等温线、吸附容量、解吸率和吸附动力学。发现ZTC-1树脂对大豆皂苷吸附量大、解吸容易、吸附速度快，是一种良好的大豆皂苷吸附荆，AB-8树脂次之．选择ZTC-l树脂纯化大豆皂苷粗提液，得到大豆皂苷产品纯度为78．2％(干物质)，回收率为93．1％．     

镶嵌用固体润滑剂对锡青铜轴承摩擦学性能影响的研究

用端面摩擦试验机考察了几种镶嵌用固体润滑剂及添加剂在常温条件下对锡青铜轴承摩擦磨损性能的影响,并用X-射线衍射法、俄歇电子能谱法分析了摩擦表面转移膜的化学组成和结合情况。结果表明,几种固体润滑剂的嵌入均可提高轴承的耐磨性,并对减小摩擦系数有一定的作用;摩擦表面固体润滑剂转移膜的形成能够有效地减少摩擦副表面间的粘着现象,是改善轴承摩擦磨损性能的主要原因。     

Rhodium(III)-catalyzed synthesis of isoquinolines from aryl ketone O-acyloxime derivatives and internal alkynes

A synthetic method of isoquinolines from aryl ketone O-acyloxime derivatives and internal alkynes has been developed using [Cp*RhCl(2)](2)-NaOAc as the potential catalyst system. The present transformation is carried out by a redox-neutral sequence of C-H vinylation via ortho-rhodation and C-N bond formation of the putative vinyl rhodium intermediate on the oxime nitrogen, where the N-O bond of oxime derivatives could work as an internal oxidant to maintain the catalytic cycle.     

Amperometric Glucose Biosensor on Layer by Layer Assembled Carbon Nanotube and Polypyrrole Multilayer Film

An amperometric glucose biosensor on layer by layer assembled carbon nanotube and polypyrrole multilayer film has been reported in the present investigation. Homogeneous and stable single wall carbon nanotubes (SWNTs) and polypyrrole (PPy) multilayer films were alternately assembled on platinum coated Polyvinylidene fluoride (PVDF) membrane. Since conducting polypyrrole has excellent anti‐interference ability, protection ability in favor of increasing the amount of the SWNTs on platinum coated PVDF membrane and superior transducing ability, a layer by layer approach of polypyrrole and carbon nanotubes has provided an excellent matrix for the immobilization of enzyme. The layer‐by‐layer assembled SWNTs and PPy‐modified platinum coated PVDF membrane is shown to be an excellent amperometric sensor over a wide range of concentrations of glucose. The glucose oxidase (GOx) was immobilized on layer by layer assembled film by a physical adsorption method by cross linking through Glutaraldehyde. The glucose biosensor exhibited a linear response range from 1 mM to 50 mM of glucose concentration with excellent sensitivity of 7.06 μA/mM.     

Carboxyl-terminated dendrimer-coated bioactive interface for protein microarray: high-sensitivity detection of antigen in complex biological samples

Protein microarrays are promising tools that can potentially enable high throughput proteomic screening in areas such as disease diagnosis and drug discovery. A critical aspect in the development of protein microarrays is the optimization of the array's surface chemistry to achieve the high sensitivity required for detection of proteins in cell lysate and other complex biological mixtures. In the present study, a high-density antibody array with minimal nonspecific cellular protein adsorption was prepared using a glass surface coated with a poly(propyleneimine) dendrimer terminated with carboxyl group (PAMAM-COOH). The carboxyl-terminated dendrimer-modified surface has almost similar nonspecific cellular protein adsorption when compared to an inert PEG-modified surface. In addition, the multiple functional sites available for reaction on the dendrimer surface facilitated high-density immobilization of antibodies and efficient capture of bioanalytes. Various molecules were tested for their ability to block or deactivate the reactive carboxyl surface after antibody immobilization to further reduce the nonspecific binding. A short oligoethylene glycol (NH2-d4-PEG-COOH), was found to significantly improve the signal-to-noise ratio of the assay, resulting in higher sensitivity. The properties and functional qualities of the various surfaces were characterized by contact angle and AFM measurements. Nonspecific protein adsorption and protein immobilization as a function of dendrimer generations and sensitivity of antigen capturing from a buffer (1 pM) as well as from the complex cell lysate (10 pM) system were examined. Our detailed experimental studies demonstrated a facile method of preparing surfaces with high protein loading and low nonspecific protein binding for the development of high sensitivity protein microarrays.     

A bis(p-sulfonatophenyl)phenylphosphine-based synthesis of hollow Pt nanospheres

We report herewith the synthesis of hollow Pt nanospheres by using bis(p-sulfonatophenyl)phenylphosphine to selectively remove the Ag cores of Ag-Pt core-shell nanoparticles. Core-shell Ag-Pt nanoparticles were first obtained by the successive reduction method with a discontinuous Pt shell to allow the BSPP passage. Transmission electron microscopy imaging of the core-shell Ag-Pt nanoparticles before and after BSPP dissolution showed little changes in the particle size, indicating that the removal of the Ag cores had occurred isomorphously. The hollow Pt nanospheres, together with the predecessor Ag-Pt core-shell particles of the same size, were transferred from water to toluene and surface modified by dodecylamine in toluene. This allows the catalytic activities of solid and hollow Pt particles in room temperature methanol oxidation reaction to be compared under conditions of identical particle size and the same surface environment. The measured higher specific activity of the Pt hollow nanospheres could then be attributed unambiguously to the larger specific surface area prevalent in the porous hollow structure.     

Understanding the Origins of Nucleophilic Hydride Reactivity of a Sodium Hydride–Iodide Composite

Sodium hydride (NaH) has been commonly used as a Brønsted base in chemical syntheses, while it has rarely been employed to add hydride (H^?) to unsaturated electrophiles. We previously developed a procedure to activate NaH through the addition of a soluble iodide source and found that the new NaH–NaI composite can effect even stereoselective nucleophilic hydride reductions of nitriles, imines, and carbonyl compounds. In this work, we report that mixing NaH with NaI or LiI in tetrahydrofuran (THF) as a solvent provides a new inorganic composite, which consists of NaI interspersed with activated NaH, as revealed by powder X‐ray diffraction, and both solid‐state NMR and X‐ray photoelectron spectroscopies. DFT calculations imply that this remarkably simple inorganic composite, which is comprised of NaH and NaI, gains nucleophilic hydridic character similar to covalent hydrides, resulting in unprecedented and unique hydride donor chemical reactivity.