Effect of Temperature on the Sterilization of Isopropyl Alcohol by Liquid Propylene Oxide

Liquid propylene oxide added to a solution of isopropyl alcohol and incubated at different temperatures markedly reduced the time required to sterilize the alcohol solution.     

胰蛋白酶的高压灭菌

胰蛋白酶在酸性条件下经过高压灭菌,仍有活力.在细胞培养中,以这种方法对胰蛋白酶消毒比常规的过滤除菌更加简便,经济,安全可靠.     

Sterilization by electrohydraulic discharges

High voltage electric discharges between two electrodes immersed in a liquid (“electrohydraulic discharges”) inactivate microorganisms suspended in the liquid. The intense pulse of UV radiation emitted from the plasma formed between the electrodes causes most of the bactericidal effects, rather than shock waves, or free radicals or other chemical species formed in the liquid medium. A method of sterilizing materials without contamination from electrode debris is described. Possible applications and limitations of the technique are outlined.     

Sterilization of peat by gamma radiation

Summary The effect of gamma-radiation on the survival of microorganisms has been quantified for the natural population of two types of peat. Data for several microbial types have been separately determined by regular plating and by indirect statistical probability estimates including, a wholly enclosed invertedbottle technique for higher dose levels to exclude any possibility of post-treatment contamination. The most persistent microorganisms at intermediate dosage (2.5–3.5 Mrad) were commonly a micrococcus (which closely resembledMicrococcus radiodurans) arthrobacter-like rods, myxobacteria and amoeboid forms. The persistent organisms all survived because of high resistance to -irradiation, not because of high initial numbers. The most numerous true bacteria (including sporeformers), actinomycetes, filamentous fungi and yeasts were all readily destroyed. Although the safety margin with the commercially recommended dose of 5 Mrad is low for some of the more resistant organisms, no change is justified at this stage since the organisms most likely to survive such a dose do not seem to seriously affect the subsequent growth and survival of rhizobia. Moreover there would be some risk of radiation-induced peat toxicity if higher doses were applied and some post-irradiation contamination will be difficult to avoid in commercial production.     

Effect of Dielectric and Liquid on Plasma Sterilization Using Dielectric Barrier Discharge Plasma

Plasma sterilization offers a faster, less toxic and versatile alternative to conventional sterilization methods. Using a relatively small, low temperature, atmospheric, dielectric barrier discharge surface plasma generator, we achieved ≥6 log reduction in concentration of vegetative bacterial and yeast cells within 4 minutes and ≥6 log reduction of Geobacillus stearothermophilus spores within 20 minutes. Plasma sterilization is influenced by a wide variety of factors. Two factors studied in this particular paper are the effect of using different dielectric substrates and the significance of the amount of liquid on the dielectric surface. Of the two dielectric substrates tested (FR4 and semi-ceramic (SC)), it is noted that the FR4 is more efficient in terms of time taken for complete inactivation. FR4 is more efficient at generating plasma as shown by the intensity of spectral peaks, amount of ozone generated, the power used and the speed of killing vegetative cells. The surface temperature during plasma generation is also higher in the case of FR4. An inoculated FR4 or SC device produces less ozone than the respective clean devices. Temperature studies show that the surface temperatures reached during plasma generation are in the range of 30°C–66°C (for FR4) and 20°C–49°C (for SC). Surface temperatures during plasma generation of inoculated devices are lower than the corresponding temperatures of clean devices. pH studies indicate a slight reduction in pH value due to plasma generation, which implies that while temperature and acidification may play a minor role in DBD plasma sterilization, the presence of the liquid on the dielectric surface hampers sterilization and as the liquid evaporates, sterilization improves.     

Arenavirus Concentration by Molecular Filtration

Liter volumes of a human arenavirus pathogen (Machupo) and a nonpathogen (Tacaribe) were concentrated 30 to 100 times in less than 90 min without significant loss of particle infectivity.     

Sterilization by Means of Hydrochloric Acid Vapour

As heat sterilization of glass bottles often results in breakage and of most plastic containers in deformation, we investigated a rapid low-temperature sterilization method as an alternative. Vapour evolving from hydrochloric acid was chosen because it does not leave toxic residues which might contaminate food packed in treated containers. Vapour evolving from 0.25 ml of 31% (w/w) hydrochloric acid reduced the number of viable spores of aerobic and anaerobic bacteria in bottles (300 ml) by a factor of at least 2500 and that from 0.01 ml of 37% (w/w) hydrochloric acid reduced the number of mould spores by a factor of over 40 000 within 5 min at 20°C.     

Filtration kinetics of chitosan separation by electrofiltration

Downstream processing of chitosan requires several technological steps that contribute to the total production costs. Precipitation and especially evaporation are energy-consuming processes, resulting in higher costs and limiting industrial scale production. This study investigated the filtration kinetics of chitosan derived from cell walls of fungi and from exoskeletons of arthropods by electrofiltration, an alternative method, thus reducing the downstream processing steps and costs. Experiments with different voltages and pressures were conducted in order to demonstrate the effect of both parameters on filtration kinetics. The concentration of the biopolymer was obtained by the average factor of 40 by applying an electric field of 4 V/mm and pressure of 4 bars. A series of analytical experiments demonstrated the lack of structural and functional changes in chitosan molecules after electrofiltration. These results, combined with the reduction of energy and processing time, define the investigated method as a promising downstream step in the chitosan production technology.     

臭氧对微生物杀菌作用的初步研究

以稀释平板计数法 ,测定了臭氧对水体和空气环境的消毒杀菌作用。结果表明 :随着臭氧浓度 (时间 )的增加 ,对各类微生物杀灭率明显上升 ,除了芽孢杆菌外 ,杀灭率可以达到 1 0 0 %。