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CdTe quantum dots (QDs) were prepared in aqueous solution using various mercaptocarboxylic acids such as mercaptopropionic acid (MPA), mercaptoethylamine (MEA), and L-cysteine (L-Cys) as stabilizing agents. The pH control of QD suspensions is essential when using fluorescent QDs in biological systems. The pH-dependent photoluminescence (PL) of MPA-and L-Cys-stabilized CdTe QDs was systematically investigated. Experimental results showed that CdTe-L-Cys is effective within a wider pH range than CdTe-MPA and CdTe-MEA, although it is ineffective in the vicinity of the isoelectric point, which makes CdTe-L-Cys quantum dots potentially suitable as a biological labeling probe under physiological conditions. Meanwhile, the effect of stabilizer structure on QD size was studied by comparing CdTe-MPA and CdTe-L-Cys QDs using x-ray diffraction, x-ray photoelectron spectroscopy and transmission electron microscopy. The results indicated that the coordination of amines with cadmium reduced the activity of Cd precursors, and the coordination of S with the CdTe QDs affected their crystal structure, resulting in the formation of relatively large CdTe-L-Cys quantum dots.

A series of TiAlN/Si3N4 nano-multilayer films with various Si3N4 layer thicknesses were prepared by reactive magnetron sputtering. These multilayers were then annealed at temperatures ranging from 600 to 900°C in air for 1 hour. The composition, microstructure, and mechanical properties of the films were characterized by energy dispersive x-ray spectroscopy, x-ray diffraction, scanning electron microscopy, and nanoindentation. It reveals that under the template effect of TiAlN layers in multilayers, as-deposited amorphous Si3N4 is crystallized and grows coherently with TiAlN layers when Si3N4 layer thickness is below 0.6 nm. Correspondingly, the hardness and elastic modulus of the multilayers increase significantly. With further increase in the layer thickness, Si3N4 transforms into amorphous, resulting in a decrease of hardness and modulus. The TiAlN/Si3N4 nano-multilayers could retain their superlattice structure even up to 900°C. The small decrease in the hardness of multilayers annealed below 800°C was correlated to the release of compressive stress in multilayers. However, oxidation was found on the surface of multilayers when annealed at 800°C, which resulted in a marked decrease in the hardness of multilayers. The multilayers presented higher hardness as compared with the monolithic TiAlN film.

The interaction mechanism of threonine (Thr) on the sidewall of (8, 8) single-walled carbon nanotubes (CNTs) was investigated by density functional tight-binding method. All the functional groups of Thr were used to interact with the surface of CNT. The structural parameters were analyzed to identify the noncovalent interactions, and the binding energy and strain energy were used to indicate the binding properties. We found that the CH/p interactions play more important roles than NH/ p and OH/p interactions in stabilizing the complex structures. Furtherly, the charge transfer properties, density of states (DOS) and partial density of states, and highest occupied molecular orbitals and lowest unoccupied molecular orbitals were also studied to illustrate the adsorbed interactions. The results show that the DOS structure of CNT could be modified by the adsorption of Thr, and, therefore, the conductivity of CNT will be improved by introducing proper amino acids. Our data should be helpful for the design of biocompatible molecules for CNT modification.

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The pyrolysis properties of five different pyrolysis tars, which the tars from 1# to 5# are obtained by pyrolyzing the sewage sludges of anaerobic digestion and indigestion from the A 2 /O wastewater treatment process, those from the activated sludge process and the indigested sludge from the continuous SBR process respectively, were studied by thermal gravimetric analysis at a heating rate of 10 /min in the nitrogen atmosphere. The results ℃show that the pyrolysis processes of the pyrolysis tars of 1#, 2#, 3# and 5# all can be divided into four stages: the stages of light organic compounds releasing, heavy polar organic compounds decomposition, heavy organic compounds decomposition and the residual organic compounds decomposition. However, the process of 4# pyrolysis tar is only divided into three stages: the stages of light organic compounds releasing, decomposition of heavy polar organic compounds and the residual heavy organic compounds respectively. Both the sludge anaerobic digestion and the "anaerobic" process in wastewater treatment processes make the content of light organic compounds in tars decrease, but make that of heavy organic compounds with complex structure increase. Besides, both make the pyrolysis properties of the tars become worse. The pyrolysis reaction mechanisms of the five pyrolysis tars have been studied with Coats-Redfern equation. It shows that there are the same mechanism functions in the first stage for the five tars and in the second and third stage for the tars of 1#, 2#, 3# and 5#, which is different with the function in the second stage for 4# tar. The five tars are easy to volatile.