Uncoupled metabolism stimulated by chemical uncoupler and oxic-settling-anaerobic combined process to reduce excess sludge production

The effects of three uncoupled metabolic systems (conventional activated sludge process with the addition of 3,3′,4′,5-tetrachlorosalicylanilide [TCS], oxic-settling-anaerobic [OSA] process modified by insertion of a sludge-holding tank in the sludge return line, and TCS and OSA combined process) on reducing excess sludge production were studied. Compared with the control conventional activated sludge process, the most effective system was the combined process, which could reduce excess sludge production by 46.90%. The 180-d operation results confirmed that TCS is an effective chemical uncoupler in reducing the sludge yield but that it had an adverse effect on substrate removal capability, effluent nitrogen concentration, and sludge settleability. The OSA process decreased excess sludge production by only 26% but had less adverse effect on effluent quality and could improve sludge settleability. The effluent total phosphorous concentration of the three systems was slightly lower than of the control unit. Microbial populations were monitored by both microscopic and molecular biologic analysis method (polymerase chain reaction [PCR]-denaturing gradient gel electrophoresis [DGGE]). The presence of TCS caused metazoans to disappear and decreased the number and activity of protozoa. PCR amplification of 16S rRNA and sequent DGGE analysis found a shift in the diversity of the predominant species. The results imply that OSA combined with the chemical uncoupler process may effectively reduce excess sludge yield and not affect process performance significantly.     

Nanoporous TiO2 Coatings for Infrared Detectors

In GaAs based infrared detectors, a considerable part of the incident light will be reflected at the surface, thus it decreases the detectors sensitivity considerably. In this paper, a TiO₂ nanoporous coating was prepared successfully on the GaAs substrate by sol-gel method. The optical parameters of the coating were also controlled successfully. It was proved that the coating could greatly improve the transmittance of the incident light, which agrees with the theoretical results quite well. In the 2.5–6.0 m waveband, the maximum transmittance of GaAs substrate is 56%, while the transmittance of the GaAs substrate coated with a nanostructured TiO₂ coating is about 94%.     

Organic–inorganic nanocomposites prepared from fluoro-aramid and silica

Fluoro-aramid-based sol/gel-derived nanocomposites were synthesized by condensing a mixture of 4,4′-(hexafluoro-isopropylidene)dianiline and 1,3-phenylenediamine with terephthaloylchloride (TPC) in dimethylacetamide. TPC was added in slight excess to produce amide chains with carbonyl chloride end groups and then replaced with alkoxy groups using aminophenyltrimethoxysilane to develop bonding with the silica network. Mechanical, dynamic mechanical thermal, water absorption and morphological measurements were carried out on the thin hybrid films. Increase in the tensile strength and modulus was observed as compared to pristine polyamide. The thermal decomposition temperature was found in the range of 400–500 °C. The water absorption was found to be reduced with higher silica content. The glass transition temperature and the storage moduli increased with increasing silica concentration. The maximum increase in the T _g value (345 °C) was observed with 20 wt% silica. Scanning electron microscopy revealed the uniform distribution of silica in the matrix with an average particle size ranging from 8 to 50 nm.     

On the relationship betweenT 1 andT 2 for stochastic relaxation models

We consider the relaxation dynamics of two quantum levels coupled to a stochastic bath. We emphasize that even if the matrix elements of the fluctuating Hamiltonian are Gaussian, a second-order cumulant truncation is not exact. For various stochastic models, including the case of a spin-1/2 particle in a fluctuating magnetic field, we calculate 1/T ₁, the population relaxation rate, and 1/T ₂, the phase relaxation rate, up to fourth order in perturbation theory. We show that unlike the commonly accepted second-order result that 1/T ₂1/2T ₁, when fourth-order terms are included, in some instances 1/T ₂<1/2T ₁.     

Hydrodynamic equations for attractive particle systems on ℤ

Hydrodynamic properties for a class of nondiffusive particle systems are investigated. The method allows one to study local equilibria for a class of asymmetric zero-range processes, and applies as well to other models, such as asymmetric simple exclusion and misanthropes. Attractiveness is an essential ingredient. The hydrodynamic equations present shock wave phenomena. Preservation of local equilibrium is proven to hold away from the shocks. The problem of breakdown of local ergodicity at the shocks, which was investigated by D. Wick in a particular model, remains open in this more general setup.     

Syntheses of TiO2(B) nanowires and TiO2 anatase nanowires by hydrothermal and post-heat treatments

TiO₂(B) nanowires and TiO₂ anatase nanowires were synthesized by the hydrothermal processing in 10 M NaOH aq. at 150 °C followed by the post-heat treatment at 300-800 °C. As-synthesized Na-free titanate nanowires (prepared by the hydrothermal treatment and repeated ion exchanging by HCl (aq.) were transformed into TiO₂(B) structure with maintaining 1-D morphology at 300-500 °C, and further transformed into anatase structure at 600-800 °C with keeping 1-D shape. At 900 °C, they transformed into rod-shaped rutile grains. Microstructure of these 1-D TiO₂ nanomaterials is reported.     

PREPARATION OF POLYSULFONAMIDE/TiO2 NANOCOMPOSITES BY SOL-GEL

Polysulfonamide (PSA) was synthesized at room temperature, the polymerization based on terephthaloyl chloride and 3,3 '-diaminodiphenylsulfone in the common solvent N,N -Dimethyl-acetamide (DMAc). Polysulfonamide/titanium oxide nanocomposites were prepared by sol-gel method. Tetrabutyl titanate(TBT) was added into the polysulfonamide solution, at the same time ,some water was mixed to make the TBT hydrolyze. In the process, hydrochloric acid was used to catalyze the reaction. The polysulfonamide chemistry structure was characterized by FT-IR spectrum. Atomic force microscopy (AFM) was employed to observe the microstructure of the composite film. The thermal property was investigated by TGA.The results show that we have succeeded to synthesize the polysulfonamide, TiO2particles were well distributed in the composite film and average size was about 20 nm on average, the heat-resistance of nanocomposite was batter than the pure polysulfonamide.     

苯丙水溶胶的合成与性能研究(I) 聚合工艺和反应组分对聚合稳定性和胶体性能的影响

用一次投料法、半连续滴加法和单体预乳化法三种聚合工艺，合成了苯丙乳液聚合物，并加氨微细化，转化成水溶胶，考察了聚合工艺和反应组分（乳化剂，功能单体等）对苯丙乳液及其水溶胶反应稳定性和粒子大小及分布等胶体性能的影响。     

Thermally produced biodegradable scaffolds for cartilage tissue engineering

A novel process was developed to fabricate biodegradable polymer scaffolds for tissue engineering applications, without using organic solvents. Solvent residues in scaffolds fabricated by processes involving organic solvents may damage cells transplanted onto the scaffolds or tissue near the transplantation site. Poly(L-lactic acid) (PLLA) powder and NaCl particles in a mold were compressed and subsequently heated at 180 degrees C (near the PLLA melting temperature) for 3 min. The heat treatment caused the polymer particles to fuse and form a continuous matrix containing entrapped NaCl particles. After dissolving the NaCl salts, which served as a porogen, porous biodegradable PLLA scaffolds were formed. The scaffold porosity and pore size were controlled by adjusting the NaCl/PLLA weight ratio and the NaCl particle size. The characteristics of the scaffolds were compared to those of scaffolds fabricated using a conventional solvent casting/particulate leaching (SC/PL) process, in terms of pore structure, pore-size distribution, and mechanical properties. A scanning electron microscopic examination showed highly interconnected and open pore structures in the scaffolds fabricated using the thermal process, whereas the SC/PL process yielded scaffolds with less interconnected and closed pore structures. Mercury intrusion porosimetry revealed that the thermally produced scaffolds had a much more uniform distribution of pore sizes than the SC/PL process. The utility of the thermally produced scaffolds was demonstrated by engineering cartilaginous tissues in vivo. In summary, the thermal process developed in this study yields tissue-engineering scaffolds with more favorable characteristics, with respect to, freedom from organic solvents, pore structure, and size distribution than the SC/PL process. Moreover, the thermal process could also be used to fabricate scaffolds from polymers that are insoluble in organic solvents, such as poly(glycolic acid). Cartilage tissue regenerated from thermally produced PLLA scaffold.     

聚甲基苯基乙烯基硅氧烷固相微萃取探头的特性

用溶胶－凝胶及自由基引发交联方法，成功地制备了聚甲基苯基乙烯基聚硅氧烷和羟基硅油复合涂层的固相微萃取探头，与进口商用探头比较，研制的探头对芳香化合物具有高的萃取能力和热稳定性（350℃）以及长的使用寿命。