Sterilization development

Recent sterilizer developments have led to the use of dry-heat sterilizing tunnels where heat transfer is achieved by infra-red irradiation or by forced convection in filtered laminar airflow tunnels. Items to be sterilized are placed on a conveyer belt and pass through a high-temperature zone (250 - 300 + °C) over a period of several minutes. 

Porteus A process for conditioning sewage sludge by heating under pressure to 180 to 220°C for approximately one hour. The solid product is easy to de-water and is sterile. Developed and used in Germany in the 1980s. 

Transfer to full-scale sterile development batches... 

Maintenance of conditions ia the culture environment that keep stress to a minimum is one of the best methods of a voiding diseases. Vacciaes have beea developed agaiast several diseases and more are under development. Selective breeding of animals with disease resistance has met with only limited success. Good sanitation and disiafection of contaminated faciUties are important avoidance and control measure. Some disiafectants are Hsted ia Table 6. Poad soils can be sterilized with burnt lime (CaO), hydrated lime [Ca(OH)2], or chlorine compounds (12). 

The discovery in 1900 of the existence of blood groups, together with improved understanding of the importance of sterile conditions, paved the way to modem blood transfusion therapy. In 1915, the feasibiUty of storage of whole blood was demonstrated. During World War I, the optimal concentration of citrate for use as an anticoagulant was determined. This anticoagulant was used until 1942, when the acid—citrate—dextrose (ACD) solution was developed. 

Milk has been a source for food for humans since the beginning of recorded history. Although the use of fresh milk has increased with economic development, the majority of consumption occurs after milk has been heated, processed, or made into butter. The milk industry became a commercial enterprise when methods for preservation of fluid milk were introduced. The successful evolution of the dairy industry from small to large units of production, ie, the farm to the dairy plant, depended on sanitation of animals, products, and equipment cooling faciUties health standards for animals and workers transportation systems constmction materials for process machinery and product containers pasteurization and sterilization methods containers for distribution and refrigeration for products in stores and homes. 

Product Heat Treatment. Equivalent heat treatment for destmction of microorganisms or inactivation of enzymes can be represented by plotting the logarithm of time versus temperature. These relationships were originally developed for sterilization of food at 121.1°C, therefore the time to destroy the microorganism is the V value at 121.1°C (250°F). The slope of the curve is and the temperature span is one log cycle. The heat treatment at 131°C for one minute is equivalent to 121.1°C for 10 minutes (Fig. 10). 

Packaging. Aseptic packaging was developed in conjunction with high temperature processing and has contributed to make sterilized milk and milk products a commercial reaUty. 

Medical and health-care related appHcations consume about 21,000 t of polycarbonate aimuaHy. Polycarbonate is popular because of its clarity, impact strength, and low level of extractable impurities. Special grades have been developed to maintain clarity and resistance to yeHowing upon gamma radiation sterilization (qv) processes. Leisure and safety appHcations are many and varied, accounting for about 22,000 t of consumption aimuaHy. The... 

Industrial sterilization cycles tend to vary considerably, not only from manufacturer to manufacturer, but often from product type to product type, depending on the bioburden present on a given load. Chemical indicators have historically been used only to differentiate between sterilized and nonsterilized packages. More recent developments have resulted in the availability of chemical dosimeters of sufficient accuracy to permit their appHcation either as total monitors or as critical detectors of specific parameters. 

The selection of an appropriate steam-sterilization cycle must be made after a carefiil study of the nature of the articles to be sterilized, the type and number of organisms present, type and size of each package, and type of packaging material used. Cycle-development studies may be conducted using fiiU autoclave loads. 

Other Sterilants. Sterilization methods, developed in response to the requirements of a low temperature, noncorrosive stedlant and rapid turnaround time required by most hospitals, include use of hydrogen peroxide vapor, hydrogen peroxide plasma, and peroxy acetic acid. Acceptance of these methods was not universal as of this writing (ca 1996). 

ElectrolyticaHy generated hypochlorite may be used for the oxidative destmction of cyanides (qv) or the sterilization of domestic wastes. Several on-site systems for swimming pool sterilization and municipal waste treatment works have been developed. One of these systems is described in Reference 124. On-site production and immediate use of chlorine is considered safer than the transportation of chlorine. 

The first two categories, clarifying and crossflow filters, have been very well developed and optimized for use in biotechnology and standard wastewater treatment applications. Equipment is easily available for these applications, whether as small 0.2 micron sterilizing filter used to terminally sterilize 100 ml of product solution, or a small 500 ml crossflow filter used to concentrate a small amount of antibody solution. Many vendors of this equipment to wastewater treatment applications have their origins in the CPI (Chemical Process Industries), and have incorporated many of the scale-up and optimization properties developed in much larger units used in large scale chemical production. As a result, these two filtration unit operations are one of the most optimized and efficient used in wastewater treatment. 

As described in U.S. Patent 2,929,763, methandrostenolone may be made by a fermentation route. 2 g of sodium nitrate, 1 g of primary potassium orthophosphate, 0.5 g of magnesium sulfate heptahydrate, 0.5 g of potassium chloride, 50 g of glucose and 1 g of Difco yeast extract are dissolved in one liter of tap water, brought to pH 5 by addition of a sodium hydroxide solution and sterilized. The resulting nutrient solution is inoculated with 50 cc of a 4-day-old shaking culture of Didyniel/a lycopersici and shaken for 48 hours at 27 C, whereby the culture becomes well developed. 

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