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PubMed1983

Heating by microwave, hot air, and flowing steam to eliminate inoculated Salmonella from poultry feed.

Poultry feed samples (mash) obtained from a commercial mill were inoculated with either 100 or 5,000 cells/g of a marker strain of Salmonella montevideo. Samples (125 g) were then placed in a microwave oven at power settings of 1.5 or 2.0 kW for 60, 90, or 120 sec; a hot air oven at 99 C (210 F) or 110 C (230 F) for 15, 30, 45, or 60 min; or a flowing steam chamber for 1, 5, 10, or 20 min. Temperature, moisture, and presence of the inoculated S. montevideo were determined in all samples before and after treatment. Feed samples placed in the microwave oven reached a maximum temperature of 186 C (367 F) and had a final moisture content as low as .8%. About 25% of the samples inoculated with 100 cells/g and about 40% of those inoculated with 5,000 cells/g remained positive after treatment. In the hot air oven, feed reached a maximum temperature of 93 C (200 F) with a moisture level after heating of about 4%. Salmonellae were recovered from 35 and 60% of the low and high inoculum level samples, respectively. In flowing steam, maximum feed temperature was 90 C (194 F) with a final moisture level of 15%. After 1, 5, 10, and 20 min of flowing steam, 100, 90, 60, and 0% of the samples were found to contain salmonellae, respectively. All treatments occasionally eliminated salmonellae from the samples, but results were inconsistent and unpredictable.

Air↗
PubMedDate not supplied

Steam sterilization: a suitable alternative?

Extracorporeal blood-circuit devices can be sterilized by ethylene oxide (EtO), irradiation, or steam. The majority of these devices are sterilized by the first two processes, and the use of steam sterilization seems to be limited. This article compares the different processes, discusses their advantages and disadvantages, and makes a case for sterilizing these products by steam.

Ethylene Oxide↗
PubMedDate not supplied

Principles of steam sterilization.

Moist heat in the form of saturated steam under pressure, is by far the most reliable medium, known for the destruction of all forms of microbial life. Steam sterilisation, therefore, is the most economical, effective and widely used method of seeking sterilisation in hospital practice. This article aims at describing the principle mechanism that makes steam an effective destruction of micro-organisms, the equipment that is most commonly used for the purpose and the practical methods of testing for sterility. The application of these principles, it is hoped, will ensure standardisation and quality control of routine sterilisation practice in hospitals thus, contributing towards the reduction in the incidence of hospital acquired infection.

Central Supply, Hospital↗
PubMedDate not supplied

Evaluation of the effects of fragmented steam exposure cycles on the survival of bacterial spores.

The purpose of this study was to examine the population and resistance characteristics of bacterial spores which have been exposed to an abbreviated steam sterilization cycle. The philosophy of many pharmaceutical manufacturers is to require a second complete terminal sterilization cycle in the event of an unplanned interruption during the terminal sterilization of a production batch. The impact of abbreviated steam sterilization cycles was examined for their effect on the survivability and resistance of bacterial spores following an inadequate sterilization cycle. Steam sterilization cycles of two minutes and four minutes were performed on separate groups of Biological Indicator spore strips. These groups were then held at room temperature and re-exposed to a range of sterilization conditions after 24, 48, and 72 hours, i.e., start cycle, abort, hold, start cycle, abort. Spore survivor curves were calculated and resistance estimations were determined. The results of the study indicated that the log level of the surviving spores remained fairly constant, but variability within groups increased as sterilization time increased. The resistance of these surviving spores, as measured by D value, also remained relatively constant throughout the holding period. Abbreviated cycles were similarly conducted on ampules containing a spore suspension, and the spore populations and moist heat resistances were determined over time. Contrary to the spore strip, the population of the subject ampules was less stable showing a gradual decline over the same observation period. The study also included a comparison of the surviving population of short and long fragmented cycles. The results of this study demonstrate that a second complete sterilization cycle is unnecessary to assure the absence of living matter in the sterilized units.

Spores, Bacterial↗
PubMed2004

[Establishment of rat model of scalding with high pressure steam].

OBJECTIVE: To establish a rat model of scalding with controllable depth and area by high pressure steam. METHODS: High pressure steam apparatus consisting of an autoclave and a self-made scalding frame was employed in the study. The rats were inflicted with scalding with 0.12 Mpa (1 Mpa = 7500 mmHg) high pressure steam on the back through a hole of 2.6 cm in diameter for 3, 4, 5, 6, 7, 8, 9 and 10 seconds, with five wounds at each time point. The tissue samples were harvested at 24 post injury hour (PIH) for pathomorphological examination. The depth of scald was measured, and injury to the sweat gland and hair follicles injury, the hair growth in scalded area, and the wound healing condition were observed with Photoshop software. RESULTS: There was positive correlation between the scalding depth and scalding time. The injury time for superficial and deep partial thickness burn and full thickness burn were 3, 5 and 7 seconds respectively. The wound healing time was similar even the scalding became more and more serious when injury time increased from 7 to 10 seconds. CONCLUSION: The scalding depth and area in this model could be controlled, and the degree of scald injury could be graded accurately with easy manipulation. The result showed that it was an ideal model of skin burn wound.

Animals↗
PubMedDate not supplied

Bioequivalent chemical steam sterilization indicators.

Biological indicators used to monitor steam sterilization cycles have two major shortcomings--the incubation period needed to determine if sterilization was accomplished, and the reliance on test packs for gathering information in each load. Chemical indicators do not suffer from these shortcomings. Chemical indicators can respond to time, temperature, and steam parameters to thus parallel the BI reaction. Nine commercially available chemical indicators and four biological indicators were evaluated under the conditions of dry heat, in a biological indicator-evaluator resistometer vessel, and in a hospital sterilizer. The results indicate that wider use of integrated chemical steam sterilization indicators is recommended.

Geobacillus stearothermophilus↗
PubMed1996

[The effect of growth media on recovery of test microorganisms after exposure to saturated steam under pressure].

The aim of this study was to find out which growth media give the best condition for the development of test bacteria after exposure to saturated steam under pressure. The test organisms were strains of Bacillus subtilis NCTC 3610 and Bacillus stearothermophilus NCTC 8923. The test prepared from spore suspension were exposed to saturated steam under pressure 0.2 atn-B.subtilis, and 0.7 atn-B. stearothermophilus with various length of exposure /sublethal conditions/. After the exposure the tests were placed in growth media. The obtained results show that the compositions of the medium in which spore-forming bacteria are grown after the exposure under sublethal conditions to saturated steam under pressure affects the recovery of the test organism. The media with glucose, tryptose and L-alanine provided the best conditions for growth.

Alanine↗
PubMed1976

Collaborative study of accelerated development of latent fingerprint images on paper by application of steam.

Nine latent fingerprint examiners participated in a collaborative study in the use of a steam iron to accelerate chemical development of latent images on bond and newsprint papers treated with a 0.5% solution of ninhydrin in acetone. Four latent images were placed on each paper by the Associate Referee during an 8 hr period. The papers were paired and numbered 1, 2, and 3. Three pairs were mailed to each collaborator who treated Pair 1 by dipping, Pair 2 by brushing or swabbing, and Pair 3 by spraying. After air-drying, the papers were subjected to heat and steam from a household steam iron until the images developed. The average time for developing all images was 5.8 min/paper. Of the total images available, 92.1% were developed to some degree; 47.9% of these images or 43.5% of all images were identified by the collaborators. The method has been adopted as offical first action.

Dermatoglyphics↗
PubMed1991

High-speed STEAM MRI of the human heart.

High-speed STEAM MR images of the normal human heart were obtained from single cardiac cycles using a 2.0-T whole-body system equipped with conventional 10 mT m-1 gradients. The single-shot 90 degrees-TE/2-90 degrees-TM-(alpha-TE/2-Acq)n pulse sequence acquires n differently phase-encoded stimulated echoes. Measuring times of 127-254 ms were achieved using a "repetition time" of 3.96 ms in conjunction with data matrices of 32-64 x 128 pixels covering a field-of-view of 250-350 mm. The sequence provides easy access to anatomical short-axis and long-axis views of the heart by single and double oblique rotation of the image orientation. STEAM images resemble the features of spin-echo images with respect to chemical shifts, susceptibilities, and flow. Thus, no additional techniques are required for the suppression of blood signals. EKG-triggered acquisitions demonstrate that slice-selective STEAM sequences using short TM intervals allow an unambiguous delineation of those parts of the myocardium that remain stationary within the selected plane throughout the entire imaging process. Neither spins leaving nor entering the slice defined by the initial 90 degrees RF pulses give rise to a stimulated echo and therefore do not contribute to the resulting image.

Heart↗
PubMed1989

Comparison of single-shot localization methods (STEAM and PRESS) for in vivo proton NMR spectroscopy.

Two single-shot localization techniques, STEAM and PRESS, are analyzed with regard to specifications for in vivo localized proton NMR. In particular, attention is paid to optimum signal intensity per unit volume, sensitivity to motion and diffusion, shortest attainable echo time, water suppression and editing possibilities. Experimental results are shown for cat brain at 4.7 T and human brain at 1.5 T. Both STEAM and PRESS are highly effective localization methods. For long echo times, PRESS is the method of choice, because it offers a factor of two gain in signal intensity. In addition, the method is less sensitive to motion and diffusion, and not susceptible to multiple-quantum effects. STEAM offers advantages for observation of (coupled) metabolites with short T2, because (a) shorter TEs can be attained and (b) effective water suppression sequences can be implemented without penalty in echo time. Differences relating to editing possibilities and B1 dependence, possibly important in choosing a method, are discussed.

Animals↗
PubMed2002

Molluscicidal and antifungal activity of Erigeron speciosus steam distillate.

The steam-distilled fraction of the aerial parts of Erigeron speciosus (Lindl) DC was tested for activity against strawberry plant pathogenic fungi Botrytis cinerea Pers ex Fr, Colletotrichum acutatum Simmonds, C fragariae Brooks, C gloeosporioides (Penz) Penz & Sacc, and the intermediate host snail Planobdella trivolvis that harbors the trematode, Bolbophorus confusus, that infests and causes severe infections in pond-raised catfish in the Mississippi Delta region of the USA. Bioautography on silica TLC plates demonstrated antifungal activity in the steam distillate. Preliminary bioassays of the steam distillate indicated the presence of phytochemicals toxic to P trivolvis. The bioactive compounds methyl 2Z, 8Z-deca-2,8-diene-4,6-diynoate and its 2E, 8E isomer were isolated by bioassay-guided fractionation and chromatographic techniques and identified by 1H NMR spectroscopy.

Alkynes↗
PubMed2000

Effects of Burn-off and Activation Temperature on Preparation of Activated Carbon from Corn Cob Agrowaste by CO(2) and Steam.

Previous studies have successfully demonstrated that corn cob is a suitable precursor for production of good activated carbon by chemical activation. However, respond to the need for cleaner production, this study focuses on the physical activation by gasifying agents such as CO(2) and steam. The activation temperatures under investigation are 1073 and 1173 K. Within the limit of 50 wt% burn-off, experimental results reveal that the BET surface area, pore volume, and average pore diameter of the resulting activated carbon generally increase with the extent of burn-off in both gasifying agents and at both temperatures. The higher activation temperature can overcome the drawbacks of a longer period of activation required to attain larger surface area and can offer higher potential to produce activated carbon of greater adsorption capacity from agriculture wastes such as corn cobs. Additionally, the BET surface areas of properly prepared activated carbons can satisfy commercial requirements, when compared with commercial activated carbon. The BET surface areas of the activated carbons after about 71 and 59 wt% burn-off of CO(2) and steam activations at 1173 K are 1705 and 1315 m(2)/g, respectively, indicating high adsorption capacities. Thus, it is feasible to produce high-quality microporous activated carbon from corn cob agrowaste using N(2) carbonization followed by physical activation with CO(2) or steam. Copyright 2000 Academic Press.

Journal Article↗
PubMed1996

Density-matrix calculations of the 1.5 T citrate signal acquired with volume-localized STEAM sequences.

Citrate detection and quantitation with proton spectroscopic methods are of current interest as potential tools in the diagnosis and staging of prostate cancer. The stimulated echo acquisition mode (STEAM) sequence is a commonly used volume-localization method for detecting citrate signal. Since the 1H citrate resonance at clinically available field strengths arises from a strongly coupled two-spin system, the 90 degrees RF pulses and localizing gradients used in STEAM sequences result in a complicated dependence of signal intensity on timing intervals and gradient amplitudes. The density-matrix formalism has been applied to arrive at a general solution to this problem. Citrate-signal properties at 1.5 T for different gradient localization schemes are examined with the solution. Optimal interpulse delays, deleterious gradient balances, zero-quantum oscillations with mixing time, and a low-frequency, large-amplitude oscillation with echo time are identified for signals acquired with the standard disposition of gradients in STEAM. The generality of the solution also allows for an examination of non-standard gradient disposition schemes for enhancing citrate signal and for quantifying the sensitivity of such approaches to both field inhomogeneities and off-resonance effects.

Citric Acid↗
PubMed1998

Saccharification and alcohol fermentation in starch solution of steam-exploded potato.

Steam explosion pretreatment of potato for the efficient production of alcohol was experimentally studied. The amount of water-soluble starch increased with the increase of steam pressure, but the amounts of methanol-soluble material and Klason lignin remained insignificant, regardless of steam pressure. The potatoes exploded at high pressure were hydrolyzed into a low molecular liquid starch, and then easily converted into ethanol by simultaneous saccharification and fermentation using mixed microorganisms: an amylolytic microorganism, Aspergillus awamori, and a fermentation microorganism, Saccharomyces cerevisiae. The maximal ethanol concentration was 4.2 g/L in a batch culture at 15 g/L starch concentration, and 3.6 g/L in a continuous culture fed the same starch concentration. In the fed-batch culture, the maximal ethanol concentration increased more than twofold, compared to the batch culture.

Aspergillus↗
PubMed2005

Validation of glutathione quantitation from STEAM spectra against edited 1H NMR spectroscopy at 4T: application to schizophrenia.

OBJECTIVE: Quantitation of glutathione (GSH) in the human brain in vivo using short echo time 1H NMR spectroscopy is challenging because GSH resonances are not easily resolved. The main objective of this study was to validate such quantitation in a clinically relevant population using the resolved GSH resonances provided by edited spectroscopy. A secondary objective was to compare several of the neurochemical concentrations quantified along with GSH using LCModel analysis of short echo time spectra in schizophrenia versus control. MATERIALS AND METHODS: GSH was quantified at 4T from short echo STEAM spectra and MEGA-PRESS edited spectra from identical volumes of interest (anterior cingulate) in ten volunteers. Neurochemical profiles were quantified in nine controls and 13 medicated schizophrenic patients. RESULTS: GSH concentrations as quantified using STEAM, 1.6 +/- 0.4 micromol/g (mean +/- SD, n = 10), were within error of those quantified using edited spectra, 1.4 +/- 0.4 micromol/g, and were not different (p = 0.4). None of the neurochemical measurements reached sufficient statistical power to detect differences smaller than 10% in schizophrenia versus control. As such, no differences were observed. CONCLUSIONS: Human brain GSH concentrations can be quantified in a clinical setting using short-echo time STEAM spectra at 4T.

Adult↗
PubMed1987

Blood gas studies in dogs with severe steam inhalation injury.

The dynamic changes in blood gases in 34 dogs suffering severe steam inhalation injury were studied during the first 14 days post-burn to determine the effects of inhalation injury on lung function. Nineteen dogs received only severe steam inhalation injury, while 15 other dogs received both 30 per cent total body surface area (TBSA) deep burns and steam inhalation injury. The results showed marked reductions of PaO2, PaCO2, AB, SBE, T-CO2, SB, BBp, pHNR and SatO2 (P less than 0.05 approximately 0.01), whereas the P(A-a)O2 increased (P less than 0.05 approximately 0.01) within week 1 post-burn in both groups. These data suggest that the injured animals were suffering from hypoxaemia and respiratory alkalosis induced by disturbance of the gas-exchange function of the lungs. There was also metabolic acidosis, which was closely related to high fever, excessive catabolism, and particularly to hypoxaemia in week 1 post-burn. If the animals survived through the critical period (1-7 days post-burn), most of the abnormal gas parameters then gradually returned to the pre-burn levels. It is clear, therefore, that blood gas monitoring in patients with inhalation injury is not only of diagnostic importance but also of prognostic value.

Acidosis, Respiratory↗
PubMed1992

Localized phosphorus NMR spectroscopy: a comparison of the FID, DRESS, CRISIS/CODEX, and STEAM methods in vitro and in vivo using a surface-coil.

The FID, DRESS, CRISIS/CODEX, and STEAM techniques for localized 31P NMR spectroscopy were compared using a Siemens Magnetom SP63 1.5 T whole-body imager and a surface-coil, 80 mm in diameter, acting as transmitter and receiver coil. The comparison was performed with phantom experiments and human in vivo investigations on the calf muscle. The phantom experiments which used the same volume size showed a comparable signal-to-noise ratio for FID and DRESS, while the two fully localized techniques showed a reduction in signal-to-noise ratio to 76% for CRISIS/CODEX and 31% for STEAM. The in vivo measurements confirm the phantom results and reveal that CRISIS/CODEX gains a 2.5 fold higher signal-to-noise ratio than STEAM under the same conditions.

Humans↗
PubMed1996

Application of NMR imaging to steam foam flooding in porous media.

Applications of NMR imaging to examine the fluid distribution of steam foam flooding as a function of concentration and volume of surfactant solution, and residual oil saturation are described. The features examined include sweep efficiency, oil recovery, resistance factor, apparent viscosity, steam quality, and foam stability. The results illustrate that the injection procedure and residual oil saturation have a significant influence on steam foam flooding.

Magnetic Resonance Imaging↗