Effect Of Gas Atmosphere Research Articles

Catalytic hydrocracking reaction of nascent coal volatile matter under high pressure

The volatile matter evolved during the rapid pyrolysis of coal was hydrocracked over catalysts in the last stage to increase the yield of valuable products like benzene, toluene and xylenes (BTX). The effects of gas atmosphere, coal type, pyrolysis temperature, hydrocracking temperature and catalyst type were examined. The highest BTX yield, 10.4 wt%(daf), was obtained under the following conditions: Millmerran coal, H 2 pressure of 5 MPa, primary pyrolysis temperature of 800 °C, secondary hydrocracking temperature of 620 °C and with a NiMoS catalyst.

Effect of gas atmosphere on in vitro maturation of bovine oocytes

Effect of gas atmosphere on in vitro maturation of bovine oocytes

Effect of gas atmosphere on the development of one-cell bovine embryos in two culture systems

The effect of two concentrations of oxygen on the development of bovine embryos was compared using two separate co-culture systems. In Experiment I, bovine oocytes were matured and fertilized in vitro and were then co-cultured for 7 days in 20 μl drops of M199 with 10% fetal calf serum containing oviduct cells. When cultures were performed in an atmosphere of 5% CO 2 in air (20% O 2) or in a mixture of 5% CO 2, 5% O 2 and 90% N 2 (5% O 2), 22 of 179 (12%) and 56 of 179 (31%) zygotes developed to or beyond the late morula stage (P<0.0001), respectively. After freezing, thawing and 48 hours of additional culture, 2 of 21 (10%) and 18 of 53 (34%) embryos were judged viable (P<0.001) within the respective treatment groups. In Experiment II, zygotes produced by the same means were co-cultured in 0.5 ml of M199 containing 10% fetal calf serum with monolayers of buffalo rat liver (BRL) cells. In 20% O 2, 51 of 177 (29%) zygotes developed into viable embryos, while in 5% O 2 only 9 of 177 (5%) were judged viable after 7 days of culture (P<0.0001). Post-freezing survival rates were 53% and 67% for embryos from the two respective oxygen concentration treatment groups. The transfer of 20 Grade 1 frozen/thawed embryos produced by co-culture with BRL cells produced six pregnancies (30%). These experiments show that the critical effect of oxygen concentration on embryo development in vitro and the ability of embryos produced by in vitro procedures to survive freezing can be influenced by the type of culture system employed.

The effect of gas atmospheres on resistivity of indium tin oxide films at high temperature

The effects of heat treatment in Q2, O2 and N2, and Ar gases on the high temperature (500‡ C) electrical resistivity of indium tin oxide (ITO) film 52 nm thick prepared by chemical spray pyrolysis method were studied. The partial oxygen pressure effect on the resistivity was found to be\(P_{{\text{O}}_{\text{2}} }^{1/5}\) to\(P_{{\text{O}}_{\text{2}} }^{1/3.5}\). The resistivity changes for cyclic exchange of O2 by Ar gas at 500‡ C. These lead to the conclusion that chemisorption of oxygen atoms in the film surface is dominant for this thin film, for thicker films such as 640 nm oxygen diffusion is found to occur. The Langmuir model of the monolayer isothermal adsorption of oxygen atoms in the surface is applicable to the rapid change of resistivity.

Storage Life of Selected Meat Sandwiches at 4°C in Modified Gas Atmospheres

The refrigerated storage life of selected meat sandwiches packed in elevated carbon dioxide atmospheres with air or nitrogen was studied by acceptability scores of untrained panelists and by microbiological analysis. Commercially produced sandwiches, including processed meats, roast beef and hamburgers, were packed in gas impermeable film with 50% CO2 and 50% air, stored at 4°C, and compared with a frozen reference sample. Processed meat products were still acceptable up to 35 d storage, roast beef for 28 to 35 d storage, and hamburger for only 14 d. The effect of gas atmospheres with 30, 50, or 70% CO2 and either air or nitrogen, on acceptability of laboratory-packaged bologna, ham, roast beef, and hamburger, was also studied. The most significant effect was observed with hamburger samples, in which exclusion of oxygen extended storage life from 14 to 35 d. Initial product quality was a more important factor determining the length of storage life than the range of gas atmospheres between 30 and 70% CO2, except for hamburger packaged in atmospheres containing air. A universal storage life for these products cannot be recommended. However acceptance of the products by an untrained taste panel generally extends beyond achievement of maximum microbial load.

Effects of Gas Atmosphere, Storage Temperature and Storage Time on the Shelflife and Sensory Attributes of Vacuum Packaged Ground Beef Patties

ABSTRACTThe effects of modified atmosphere packaging systems on the shelflife and palatability attributes of ground beef patties were determined. Packaging systems evaluated were 100% nitrogen backflush, 100% carbon dioxide backflush and no gas backflush (no oxygen). Vacuum‐packaged samples were stored at 0, 4 and 8°C for 7, 14, and 21 days. Percent purge increased as storage temperature increased and as time in storage increased (up to 14 days of storage). Nitrogen backflush produced the lowest purge values; vacuum packaged controls had the highest levels. Kramer shear values and microbial counts increased with time in storage. Sensory traits indicated that the carbon dioxide treatment yielded higher taste panel scores. Sensory panel values decreased with time in storage.

Thermal decomposition of TPA-ZSM-5 zeolites: Effect of gas atmosphere and Si/Al ratio

The thermal analysis of TPA-ZSM-5 (Si/Al = 13.6–39.7) and TPA-silicalite in the presence of inert and oxidizing gas atmospheres has been carried out in the temperature range 303–1273 K. The decomposition of TPA cations in the presence of air is a complex exothermic process. It occurs in two steps, one between 663 and 773 K and the other between 773 and 973 K. However, the decomposition in inert (nitrogen) atmosphere is endothermic and occurs in a single step and also at lower temperatures ( < 773 K). The decomposition is strongly influenced by the Si/Al ratio. The TPA cations associated with the acid sites are more stable than those associated with the non-acid sites of the zeolite. The activation energy of the decomposition increases with the increase in the Al content of the zeolite.

Effect of gas atmosphere on the properties of ceramic ware

Effect of gas atmosphere on the properties of ceramic ware

The Effect of Gas Atmosphere on the Grinding Efficiency of Limestone in Vibration Ball Mill

In this report, the effect of gas atmosphere on the efficiency of size reduction of limestone powder is investigated experimentally by using a laboratory-scale vibration ball mill with ceramic balls (18mmφ). Air in the mill was evacuated and then replaced by other gases such as vapour phase of water, ethylether, methyl alcohol and acetone. The grinding experiment with a fine solid additive (aid) and that in a vacuum mill were also tried for comparison.The experimental results, shown in Figs. 3 and 4, reveal that the gas atmosphere of the above material increases the efficiency of limestone grinding distinctly, as same as the grinding with a solid state additive.These results can be represented by the following equations, which were proposed originally in the previous paper by one of the authors and have been modified here;SW>SWR; dSW/dE=ηr0 or (SW-SW0)=ηr0(E-Ei)SW>SWR; dSW/dE=ηr0-a(SW-SWR)n}(2)The improvement of grinding efficiency is found to be due to the increase of incipient efficiency of grinding, ηr0, the decrease of hindrance effect of grinding by fine powder produced in the mill, n, and the increase of the upper limit of Rittinger's range (SWR). The effect of these factors are summarized in Table I.From these, it can be estimated that the mechanism of the aiding effect of gas atmosphere is different from that of fine solid additive. And also there is no clear evidence that the dipole moment of gaseous material is an important factor of this aiding effect.