Structural Integration of Tellurium Oxide into Mixed-Network-Former Glasses: Connectivity Distribution in the System NaPO3–TeO2

FSodium phosphate tellurite glasses in the system (NaPO3)(x)(TeO2)(1-x) were prepared and structurally characterized by thermal analysis, vibrational spectroscopy, X-ray photoelectron spectroscopy (XPS) and a variety of complementary solid-state nuclear magnetic resonance (NMR) techniques. Unlike the situation in other mixed-network-former glasses, the interaction between the two network formers tellurium oxide and phosphorus oxide produces no new structural units, and no sharing of the network modifier Na2O takes place. The glass structure can be regarded as a network of interlinked metaphosphate-type P(2) tetrahedral and TeO4/2 antiprismotic units. The combined interpretation of the O 1s XPS data and the P-31 solid-state NMR spectra presents clear quantitative evidence for a nonstatistical connectivity distribution. Rather the formation of homootomic P-O-P and Te-O-Te linkages is favored over mixed P-O-Te connectivities. As a consequence of this chemical segregation effect, the spatial sodium distribution is not random, as also indicated by a detailed analysis of P-31/No-23 rotational echo double-resonance (REDOR) experiments. ACHTUNGTRENUNG(TeO2)1 x were prepared and structurally characterized by thermal analysis,vibrat ional spectroscopy,X-ray photoelectron spectroscopy (XPS) and a variety of complementary solid-state nuclear magnetic resonance (NMR) techniques. Unlike the situation in other mixed-network-former glasses,the interaction between the two network formers tellurium oxide and phosphorus oxide produces no new structural units,and no sharing of the network modifier Na2O takes place. The glass structure can be regarded as a network of interlinked metaphosphate-type P(2) tetrahedral and TeO4/2 antiprismatic units. The combined interpretation of the O 1s XPS data and the 31P solid-state NMR spectra presents clear quantitative evidence for a nonstatistical connectivity distribution. Rather,the formation of homoatomic P O P and Te O Te linkages is favored over mixed P O Te connectivities. As a consequence of this chemical segregation effect,the spatial sodium distribution is not random,as also indicated by a detailed analysis of 31P/23Na rotational echo double-resonance (REDOR) experiments.

Species transformation of trace elements and their distribution prediction in dyestuff residue incineration

The release of heavy metals from the combustion of hazardous wastes is an environmental issue of increasing concern. The species transformation characteristics of toxic heavy metals and their distribution are considered to be a complex problem of mechanism. The behavior of hazardous dyestuff residue is investigated in a tubular furnace under the general condition of hazardous waste pyrolysis and gasfication. Data interpretation has been aided by parallel theoretical study based on a thermodynamic equilibrium model based on the principle of Gibbs free energy minimization. The results show that Ni, Zn, Mn, and Cr are more enriched in dyestuff residue incineration than other heavy metals (Hg, As, and Se) subjected to volatilization. The thermodynamic model calculation is used for explaining the experiment data at 800 degrees C and analyzing species transformation of heavy metals. These results of species transformation are used to predict the distribution and emission characteristics of trace elements. Although most trace element predictions are validated by the measurements, cautions are in order due to the complexity of incineration systems.

Deformation behaviour of electrodeposited nanocrystalline Ni with broad grain size distribution

In the present work, nanocrystalline Ni (nc-Ni) with a broad grain size distribution (BGSD) of 5-120 nm and an average grain size of 27.2 nm was prepared. The BGSD nc-Ni sample shows a similar strength and good ductility in comparison with electrodeposited nc-Ni with a narrow grain size distribution. The intracrystalline dislocation network was observed in the post-deformed microstructure confirming the conventional intracrystalline dislocation sliding mechanism in BGSD nc-Ni. The uniaxial tensile loading-unloading-loading deformation shows BGSD nc-Ni has the capability to store dislocations in the grain interior, which is very limited compared with that of coarse grained metals. For BGSD nc-Ni, the strain rate sensitivity of flow stress m enhances with decreasing strain rate. At the strain rate of 5 x 10(-6) s(-1), m was estimated to be 0.055. At the corresponding strain rate, the enhanced ductility along with the decreased strength was achievable, indicating activation of other deformation mechanisms, e. g. grain boundary sliding or diffusion.

Preparation and luminescence properties of in situ formed lanthanide complexes covalently grafted to a silica network

Lanthanide-doped sol-gel-derived materials are an attractive type of luminescent materials that can be processed at ambient temperatures. However, the solubility of the lanthanide complexes in the matrix is a problem and it is difficult to obtain a uniform distribution of the complexes. Fortunately, these problems can be solved by covalently linking the lanthanide complex to the sol-gel-derived matrix. In this study, luminescent Eu3+ and Tb3+ bipyridine complexes were immobilized on sol-gel-derived silica. FT-IR, DTA-TG and luminescence spectra, as well as luminescence decay analysis, were used to characterize the obtained hybrid materials. The organic groups from the bipyridine-Si moiety were mostly destroyed between 220 and 600 degreesC. The luminescence properties of lanthanide bipyridine complexes anchored to the backbone of the silica network and the corresponding pure complexes were comparatively investigated, which indicates that the lanthanide bipyridine complex was formed during the hydrolysis and co-condensation of TEOS and modified bipyridine. Excitation at the ligand absorption wavelength (336 nm for the hybrid materials and 350 nm for the pure complexes) resulted in strong emission of the lanthanide ions: Eu3+ D-5(0)-F-7(J) (J = 0, 1, 2, 3, 4) and Tb3+ D-5(4)-F-7(J) (J = 6, 5, 4, 3) emission lines due to efficient energy transfer from the ligands to the lanthanide ions.

A method to construct a third-generation horseradish peroxidase biosensor: Self-assembling gold nanoparticles to three-dimensional sol-gel network

A novel method for fabrication of horseradish peroxidase biosensor has been developed by self-assembling gold nanoparticles to a thiol-containing sol-gel network. A cleaned gold electrode was first immersed in a hydrolyzed (3-mercaptopropyl)-trimethoxysilane (MPS) sol-gel solution to assemble three-dimensional silica gel, and then gold nanoparticles were chemisorbed onto the thiol groups of the sol-gel network. Finally, horseradish peroxidase (HRP) was adsorbed onto the surface of the gold nanoparticles. The distribution of gold nanoparticles and HRP was examined by atomic force microscopy (AFM). The immobilized horseradish peroxidase exhibited direct electrochemical behavior toward the reduction of hydrogen peroxide. The performance and factors influencing the performance of the resulting biosensor were studied in detail. The resulting biosensor exhibited fast amperometric response (2.5 s) to H2O2. The detection limit of the biosensor was 2.0 mumol L-1, and the linear range was from 5.0 mumol L-1 to 10.0 mmol L-1. Moreover, the studied biosensor exhibited high sensitivity, good reproducibility, and long-term stability.

膨胀土化学改性实验研究

Expansive soil is a kind of typical unsaturated soil with characteristics of high swelling-shrinking deformation, cracks and over consolidation. It is very harmful to civil engineering, As a new processing method deal with expansive soil, Chemistry treatment has widespread applied in developed countries such as Europe and America, and also gained remarkable result. Based on the embankment filling soil improving testing projects in Meng-Xin freeway, this paper proposed a new processing method to expansive soil embankment wrapped with PAS-treated soil, experimental study of expansive soil chemical improved by PAS is been carried out. The water content change is the external factor which causes expansive soil to have swelling-shrinkage deformation. this reflected that the soil body swelling-shrinkage characteristic mainly depends on its mineral ingredient and the soil-water mutual function. This paper takes expansive soil as one kind of ordinary high plastic clay from angle of clay-water mutual function explained the expansive soil swelling-shrinkage deformation mechanism on microscopic. And take this swelling-shrinkage mechanism as the master line, Cooperates with the China Academy of Chemistry, we developed the new method PAS treatment, trough ionic exchange, joint, package and flocculation, the stronger static electricity function weakened the level through adsorption and the stronger static electricity function, PAS can weakened the negative charge repulsion between levels, causes the electric potential to reduce, diffusion layer thickness to be thinner, and improves the water affinity performance of expansive soil effectively. Moreover the space network architecture compromised with PAS and soil enhanced the joint strength between the clay particles , enable the soil body to have comparatively high strength and the distortion rate. pointed proposed the PAS modified principle. Combine with the construction of experimented road, this paper sums up and presents the construction craft and technology requirement of PAS treatment to expansive soil embankment. Through many experimental studied the basic physical property, the intensity characteristic and water stability changes of expansive soil and PAS-treated soil. The results of study indicate that adding lime into the expansive soil can reduce the content of clay gain obviously, reduce the plasticity notably, increase the strength greatly, control the property of swelling and shrinking effectively, and can meliorate the stability of sucking water clearly. Simultaneity PAS don’t change the cultivate capacity of the soil, the modified slope of the embankment can adopt plant fixed slope method as ecology protection. Finally the processing effect of use different treatment has analyzed through numerical simulation, summarized the PAS chemical wrapping treatment process in the actual project application, and appraised its processing effect and the project efficiency. The research indicated that PAS chemical treatment is one effective method to improve expansive soil. Compare with long-distance replacement, especially in the high plastic expansive soil massive distribution area, PAS treatment has the very greatly economical superiority to be promoted. The study in the paper not only afforded technique method to Meng-Xin expressway construction but also important for improvement of the expressway construction theory in swelling soil areas. Key words: PAS; expansive soil; swelling-shrinkage deformation mechanism; wrapping embankment; chemical modified treatment.