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ABSTRACTSeven series of Mo2FeB2ceramic-steels with Nb/V content between 0 and 6 wt-% had been successfully fabricated by liquid phase reaction sintering. The microstructure was studied by means of field emission scanning electron microscope, energy dispersive spectroscopy and X-ray diffractometry. The hardness (HRA), transverse rupture strength (TRS) and wear resistance were also measured. The results reveal that the grain size decreased with the increase of Nb content, but had little change with the increase of V content. With the increase of Nb/V content, the hardness and TRS both enhance first and then descends. Mo2FeB2ceramic-steels with 4 wt-% Nb content show the highest hardness and TRS of HRA 90.6 and 1970 MPa and the best dry sliding wear resistance.

Seven series of Mo2FeB2ceramic-steels with Nb/V content between 0 and 6 wt-% had been successfully fabricated by liquid phase reaction sintering. The microstructure was studied by means of field emission scanning electron microscope, energy dispersive spectroscopy and X-ray diffractometry. The hardness (HRA), transverse rupture strength (TRS) and wear resistance were also measured. The results reveal that the grain size decreased with the increase of Nb content, but had little change with the increase of V content. With the increase of Nb/V content, the hardness and TRS both enhance first and then descends. Mo2FeB2ceramic-steels with 4 wt-% Nb content show the highest hardness and TRS of HRA 90.6 and 1970 MPa and the best dry sliding wear resistance.

Maize (Zea mays) seedlings were exposed for 6 h to strong irradiance (1 000 μmol m−1s−1of PPFD) at 5, 12, 17, or 25 °C, followed by an exposure to the darkness for 6 h at 22 °C. Leaf chlorophyll fluorescence, net photosynthetic rate (PN), and the amount of superoxide radicals (O2−⋅) in relation to chilling-induced photoinhibition were investigated. During the photophase, a good correlation (r=−0.879) was observed between ΦPS2(relative quantum efficiency of PS2 electron transport) and the amount of O2−⋅. Treatment with exogenous O2−⋅reduced the PNand ΦPS2as the chilling stress did, that was inhibited by specific scavenger of O2−⋅. Hence chilling-induced photoinhibition might be due to the production of O2−⋅. In contrast, in the dark period, PNand ΦPS2of the seedlings treated with the exogenous O2−⋅were enhanced, but they were inhibited by the specific scavenger of O2−⋅, showing the photoprotective role of O2−⋅in the recovery phase. Furthermore, in terms of the effect of exogenous O2−⋅on the xanthophyll cycle, the O2−⋅production suggested a promotion effect for the de-epoxidation of violaxanthin during the photophase, the epoxidation of zeaxanthin at the dark stage, and the increase of the xanthophyll pool both in the photophase and dark phase, resulting in an enhancement of the ability of non-photochemical quenching to avoid or alleviate the damage to photosynthetic apparatus.

The monomer (2-allylphenoxy)pentachlorocyclotriphosphazene (Ia) was synthesized on reacting hexachlorocyclotriphosphazene with 2-allylphenol with a phase-transfer catalyst in a dichloromethane/alkaline solution. The copolymerizations of Ia with styrene, methyl methacrylate, and vinylbenzyl chloride were investigated. No improvement in the weight conversion of the copolymerization reaction was observed when the duration of copolymerization exceeded 30 h and the reaction temperature was controlled between 60 and 80 °C. Molecular weights of the copolymers decreased with increasing molar fraction of Ia in the feed, but there was no correlation with the content of Ia in the copolymer. Reactivity ratios and Alfrey−Price parameters for the copolymers were obtained. The copolymers were characterized by using EA, GPC, TGA, and DSC. The incorporation of the phosphazene unit affected the flame-retarding properties of the copolymer. Tensile measurement showed that the copolymer of Ia reacted with methyl methacrylate was hard and brittle.

The tailor rolled blank of dual phase steel (DP-TRB) is benefit for light weight of automobiles, and contribute to the energy conservation and emission reduction of the auto industry. Two kinds of annealing process, austenitizing completely followed by cooling to intercritical temperature and intercrit ical annealing, is studied. In intercritical annealing, an inflection point inmechanical property is found at 1.5mm thickness zone (25% rolling reduction) and has big property difference between different thickness es. In the process of complet ing austenitizing followed by cooling to intercrit ical temperature, the homogenized mechanical property is shown and the difference in strength between thicknesses is 20MPa. And in this process, the influence of rolling is totally eliminated. These results can guide industrial production.

The International Commission on Radiological Protection has recently issued Publication 88, giving dose coefficients for the embryo, fetus and newborn child from intakes of selected radionuclides of 31 elements by the mother, either before or during pregnancy. The biokinetic models used for calculating these doses were based upon the available human data and the results of animal experiments. This paper summarises the approach used for the development of biokinetic and dosimetric models. It also compares the estimates of dose received by the offspring with those received by the reference adult. The main findings are that, in general, doses to the offspring are similar to or lower than those to the reference adult. For a few radionuclides, however, the dose to the offspring can exceed that to the adult. The reasons for these variations in comparative dose are examined.

Based on existing pharmacokinetic models for benzene, the distribution and retention of activity after inhalation of 14C-labelled benzene in humans were studied. Six different benzene concentrations from 0.1 to 10,000 ppm (corresponding to activity concentrations between 9.6 x 106 and 9.6 x 1011 Bq m-3) and five exposure times from 0.1 to 1000 min were considered. The cumulated activities in the different organs and tissues and the urinary excretion rates were observed to depend non-linearly on the activity intake. The fraction of activity removed via urine varies between 52 and 10% of the intake. Nevertheless, for times that are long compared to the exposure duration the urinary excretion rate is determined by the activity clearance from adipose tissue and thus decreases at a constant rate. This decrease is common for all exposure conditions examined and thus allowed determining a mean urinary excretion rate and corresponding dose coefficients for committed equivalent doses as well as for the effective dose. The uncertainty of the dose coefficients is estimated to be about 50% for the exposure range covered. A 14-day interval for the incorporation monitoring by urine activity counting seems to be reasonable.