Screening of a microbial consortium with efficient corn stover degradation ability at low temperature

To speed up the degradation of corn stover directly returned to soil at low temperature, the corn stover-degrading microbial consortium GF-20, acclimated to biological decomposition in the frigid region, was successfully constructed under a long-term limiting substrate. To evaluate its potential in accelerating the decomposition of un-pretreated corn stover, the decomposing property, fermentation dynamic and the microbial diversity were analyzed. GF-20 degraded corn stover by 32% after 15-day fermentation at 10℃. Peak activities of filter paperlyase（FPA）, β-glucosidases（CB）, endoglucanases（Cx）, and cellobiohydrolases（C1） were 1.15, 1.67, 1.73, and 1.42 U m L^–1, appearing at the 6th, 3rd, 11 th, and 9th d, respectively. The p H averaged at 6.73–8.42, and the optical density（OD） value peaked at 1.87 at the 120 h of the degradation process. Cellulase, hemicellulase and lignin in corn stover were persistently degraded by 44.85, 43.85 and 25.29% at the end of incubation. Result of denaturing gradient gel electrophoresis（DGGE） profiles demonstrated that GF-20 had a stable component structure under switching the temperature and p H. The composition of the GF-20 was also analyzed by constructing bacterial 16 S r DNA clone library and fungal 18 Sr DNA-PCR-DGGE. Twenty-two bacterial clones and four fungal bands were detected and identified dominant bacteria represented by Cellvibrio mixtus subsp., Azospira oryzae, Arcobacter defluyii, and Clostridium populeti and the fungi were mainly identified as related to Trichosporon sp.

Low Temperature Reduction Degradation Characteristics of Sinter,Pellet and Lump Ore

The reduction degradation characteristics of typical sinter, pellet and lump ore were tested with the reducing gas conditions simulating two kinds of irowmaking processes. The results show that, in the same condition of gas composition and temperature, the reduction degradation degree （RDI〈3.15mm） of sinter is high, RDI〈3.15mm of lump ore is low and RDI〈3.15 mm of pellet is in the middle level. With two kinds of gas composition simulating different iron-making processes, the reduction degradation indices （RDI） of three kinds of iron ores all present the tenden- cy of ＂inverted V-shape＂ in the temperature range from 450 to 650℃, and the RDI reach the maximum value at 550℃. The reduction degradation degrees of iron ores are extended when mixing the gas with hydrogen to increase the re duction potential, and the influence extent is discrepant for different iron ores. Colligating the increase amplitude of grains in small size fraction, the influence of reducing gas on lump ore is the greatest, the influence on sinter is the second, and the sensitivity of pellet on the reducing gas properties change is relatively small. As for the degradation form, lump ore and sinter both present the degradation ,of cracking, and the distribution of small grains generated from the cracking is in the range from 03 5 to 6. 3 mm uniformly. The lump ore presents surface cracking, while sin- ter presents integral cracking. The pellet presents the degradation of surface stripping, and the proportion of grains smaller than 0.5 mm is the highest, which is up to 90% in the grains smaller than 3.15 mm.

Fabrication and Properties of 3Y-TZP/ZrO_2 / Al_2O_3 /MgO Ceramics

Studies on the sintering, microstructure, mechanical properties and low temperature degradation behavior of yttria stabilized-tetragonal zirconia polycrystal （3Y-TZP） were carried out. The results show that the addition of Al2O3 and MgO improve the sintering at low temperatures, and cause exaggerated grain growth and the transformation of tetragonaI-ZrO2 to monoclinic-ZrO2 with corresponding changes in the mechanical properties. The addition of the yttria-free monoclinic zirconia particles change the overall yttria distribution and induce an active transformation toughening mechanism. Furthermore, the dispersed yttria-free ZrO2 can inhibit the tetragonal zirconia transformation, which is beneficial to the improvement of the low temperature degradation behavior of 3Y- TZP ceramics.

Yttria Tetragonal Zirconia Biomaterials:Kinetic Investigation

The low temperature aging behavior of polycrystalline tetragonal zirconia was investigated to explore the effects on phase transformation occurring during the process. XRD analysis was conducted for the phase identification and the tetragonal to monoclinic phase transformation was determined. The aging of tetragonal zirconia polycrystals doped with 3 mol% Y203 triggers tetragonal to monoclinic phase transformation on the surface of the specimen only, while the penetration inside the bulk of the specimen is very limited. A slight decrease in the mechanical properties was also observed after aging for 40 h. The transformation kinetics show a nucleation and growth mechanism on the specimen surface to be dominant in the low temperature aging in water environment.

Sintered Ore Sprayed by Acid and Alkaline Waste Water Resulted From Cold Rolling

In order to prevent the powdering of a sintered ore from influencing the smooth operation of a blast furnace,the conventional way to deal with it is that the CaCl2 solution is prepared by tap water,and then the solution is sprayed onto the sintered ore for improving its RDI（low temperature reduction degradation index）.The CaCl2 solution prepared by adding acid and alkaline waste water resulted from cold rolling is sprayed onto the sintered ore to improve its RDI.The values of RDI＋6.3 and RDI＋3.15 of the sintered ore which is sprayed by the CaCl2 solution with the CaCl2 concentration of 3.5%（mass percent） are increased by 17.5% and 11.63%,but the index of RDI-0.5 is decreased by 3.1% when the spraying amount of the solution is making up 0.5% of the total sintered ore sprayed in comparison with those of the sintered ore which is not sprayed by using the CaCl2 solution.Experimental results show that after the CaCl2 solutions prepared by adding the acid and alkaline waste water are sprayed on the sintered ore,RDI of the ore can be remarkably improved and therefore another way for recycling acid and alkaline waste water can be available,by which both cost for treating waste water and cost for producing a sintered ore can be decreased and environment is free of pollution by harmful substances in the waste water.