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PubMed2006

Comparison of conventional mandatory ventilation and high frequency oscillatory ventilation for treatment of acute lung injury induced by steam inhalation injury.

This study compared patho-physical indexes, respiratory mechanics, circulatory parameters and lung injury scores of acute lung injury (ALI) induced by steam inhalation injury in a New Zealand rabbit model with different ventilatory strategies: a control group which consisted of lower tidal volume (VT 6 ml/kg) and high positive end-expiratory pressure (PEEP) (9 cmH(2)O); treatment group which was high frequency oscillatory ventilation (HFOV). Eighteen rabbits were anaesthetized, sedated, neuromuscular-blocked and ventilated with above two modes at our animal laboratory of burn center. After induction of acute lung injury by steam inhalation, animals were randomly assigned to receive either conventional mechanical ventilation (CMV) or high frequency oscillatory ventilation and were grouped as CMV and HFOV group. As a result, HFOV attenuated the decrease in oxygenation and pulmonary compliance, alleviated lung tissue damage and inflammatory response. Therefore, HFOV may be a preferable option for treatment of acute lung injury induced by steam inhalation injury.

Animals↗
PubMed2005

Comparisons of porous and adsorption properties of carbons activated by steam and KOH.

In this work, fir woods and pistachio shells were used as source materials to prepare porous carbons, which were activated by physical (steam) and chemical (KOH) methods. Pore properties of these activated carbons including the BET surface area, pore volume, pore size distribution, and pore diameter were first characterized by a t-plot method based on N(2) adsorption isotherms. Highly porous activated carbons with BET surface area up to 1009-1096 m(2)/g were obtained. The steam and KOH activation methods produced carbons with mesopore content in the range 9-15 and 33-49%, respectively. The adsorption equilibria and kinetics of tannic acid, methylene blue, 4-chlorophenol, and phenol from water on such carbons at 30 degrees C were then investigated to check their chemical characteristics. The Freundlich equation gave a better fit to all adsorption isotherms than the Langmuir equation. On the other hand, the intraparticle diffusion model could best follow all adsorption processes. In comparison with KOH-activated carbons, it was shown that the rate of external surface adsorption with steam-activated carbons was significantly higher but the rate of intraparticle diffusion was much lower.

Adsorption↗
PubMed2004

Remediation of NAPL below the water table by steam-induced heat conduction.

Previous experimental studies have shown that NAPL will be removed when it is contacted by steam. However, in full-scale operations, steam may not contact the NAPL directly and this is the situation addressed in this study. A two-dimensional intermediate scale sand box experiment was performed where an organic contaminant was emplaced below the water table at the interface between a coarse and a fine sand layer. Steam was injected above the water table and after an initial heating period the contaminant was recovered at the outlet. The experiment was successfully modeled using the numerical code T2VOC and the dominant removal mechanism was identified to be heat conduction induced boiling of the separate phase contaminant. Subsequent numerical modeling showed that this mechanism was insensitive to the porous medium properties and that it could be evaluated by considering only one-dimensional heat conduction.

Environmental Monitoring↗
PubMed2002

Analysis of the steam injection at the Visalia Superfund Project with fully compositional nonisothermal finite difference simulations.

By injecting steam, over 1.1 million pounds of creosote has been recovered at the Visalia, California Superfund Site from an aquifer 102ft underground. In the first 6 weeks of injection 320,000lb of creosote were recovered or destroyed versus <1lb per day in a pump and treat. The finite difference simulator STARS1, which is widely used in the oil industry to model thermal recovery, has been used to simulate simplified models of the project, to analyze recovery mechanisms, and to demonstrate how the operation of similar projects can be improved. The simulations indicate that vaporization of dense, nonaqueous, phase liquids (DNAPLs) is the most important recovery mechanism, that liquid production is enhanced because a gas phase is present, and that the project could have been completed more rapidly if an additional injector or producer had been added in the center of the site. In addition, the mineralization (conversion to carbon dioxide) of DNAPLs could result from reaction with water, injected air or, most likely, both. The mechanisms are likely to be similar to subcritical water oxidation. While this analysis suggests methods to improve operation of future steam projects, Visalia has been a very successful demonstration of the potential of steam injection to clean up recalcitrant hydrocarbons and will be an inspiration for future projects.

Hazardous Waste↗
PubMed2002

Improved dissolution behaviour of steam-granulated piroxicam.

In this paper we prepared and characterized improved release granulates containing Piroxicam and beta-cyclodextrins (1:2.5 molar ratio), obtained by steam-aided granulation, using a one-step rotogranulator, Rotolab. These granulates were compared to those prepared by traditional wet granulation, to the physical mixture, and to the kneaded and dry granulates. The experimental data showed a significant reduction of the water amount required (50%) and of the working time, with respect to traditional wet granulation. The samples examined by scanning electron microscopy and fractal analysis revealed morphological differences related to the method of preparation: the steam-granulated material showed a diffuse porosity, as confirmed by the porosity test. Differential scanning calorimetry, infrared and X-ray analysis revealed the absence of polymorphs in the solid state of the drug. The results of the dissolution tests suggest that the steam-aided granulation may be considered a useful method to improve the in vitro dissolution rate of Piroxicam, enabling also a considerable reduction in the processing time.

Chemistry, Pharmaceutical↗
PubMed2003

Fractionation of Eucalyptus grandis chips by dilute acid-catalysed steam explosion.

Steam explosion of Eucalyptus grandis has been carried out under various pretreatment conditions (200-210 degrees C, 2-5 min) after impregnation of the wood chips with 0.087 and 0.175% (w/w) H2SO4. This study, arranged as a 2(3) factorial design, indicated that pretreatment temperature is the most critical variable affecting the yield of steam-treated fractions. Pretreatment of 0.175% (w/w) H2SO4-impregnated chips at 210 degrees C for 2 min was the best condition for hemicellulose recovery (mostly as xylose) in the water soluble fraction, reaching almost 70% of the corresponding xylose theoretical yield. By contrast, lower pretreatment temperatures of 200 degrees C were enough to yield steam-treated substrates from which a 90% cellulose conversion was obtained in 48 h, using low enzyme loadings of a Celluclast 1.5 1 plus Novozym 188 mixture (Novo Nordisk). Release of water-soluble chromophores was monitored by UV spectroscopy and their concentration increased with pretreatment severity. The yield of alkali-soluble lignin increased at higher levels of acid impregnation and pretreatment temperatures. Thermoanalysis of these lignin fractions indicated a pattern of lignin fragmentation towards greater pretreatment severities but lignin condensation prevailed at the most drastic pretreatment conditions.

Catalysis↗
PubMed2003

Microwave-assisted steam distillation for simple determination of polychlorinated biphenyls and organochlorine pesticides in sediments.

A novel sample extraction technique for polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) analysis using microwave-heating device is developed. In this study, microwave-assisted extraction (MAE) and steam distillation techniques were combined. Desorption of the anatytes from solid matrixes was accelerated with water vapor which was generated by microwave irradiation. A sample holder in a commercial microwave extraction cell kept the sample from direct contact with the organic solvent for analytes trapping during the treatment process. Therefore, relatively clean extracts were obtained with small amount of solvents. Without any cleanup steps, the obtained extract could be analyzed with gas chromatograph/mass spectrometers (GC/MS). Six PCB congeners (PCB15, 28, 70, 101, 180, 194, 209) and three OCPs (gamma-HCH, 4,4'-DDE, 4,4'-DDD) in two marine sediment samples (a sediment collected from a bay of Kyusyu Island, Japan, and a certified reference material NIST SRM1944) were analyzed by using this microwave-assisted steam distillation (MASD) technique and another extraction method (exhaustive steam distillation, MAE, and Soxhlet extraction); and comparisons of the results are shown in this report. Although recovery yields of highly chlorinated biphenyls (PCB180, 194, 209) and relatively polar OCPs (gamma-HCH, 4,4'-DDD) were low (30-60%) compared with other analytes (PCB15, 28, 70, 101, 4,4'-DDE; recovery, 80-100%), use of isotope labeled internal standards for the MASD technique gave comparable results with the values obtained by other extraction methods and the certified values in the samples.

Gas Chromatography-Mass Spectrometry↗
PubMed1999

Physical stability of ethyl diatrizoate nanocrystalline suspension in steam sterilization.

PURPOSE: To study the effects of formulation variables on the physical stability of a submicron crystal (nanocrystal) suspension under steam sterilization conditions. METHODS: Suspensions of ethyl diatrizoate nanocrystals were prepared by wet milling in the presence of the surfactant poloxamine 908. Particle size distribution and zeta potential were measured by photon correlation spectroscopy. RESULTS: On heating, the mean particle size of the nanocrystal suspension remained essentially unchanged up to 110 degrees C, the cloud point of the stabilizing surfactant, but increased significantly above that temperature. The increase in particle size was a result of particle aggregation rather than crystal growth. Adding a cloud point booster to the suspension significantly minimized the particle aggregation at high temperatures. The purity of poloxamine 908 and the tonicity agent and buffer salt used also affected the heat stability of the suspension, the latter agents apparently through altering the surfactant cloud point. CONCLUSIONS: The aggregation of the ethyl diatrizoate nanocrystalline suspension under steam sterilization conditions was a result of phase separation of the stabilizing surfactant at its cloud point. When formulated with a cloud point booster to prevent the phase-separation, the suspension maintained its physical stability under steam sterilization without any significant change in particle size distribution.

Buffers↗
PubMed1992

[The energetic utilization of rations with steamed potatoes in growing swine].

The energetic utilization of rations with steamed potatoes (40 and 50% of DM of ration) was measured in 8 growing pigs, live weight 30-70 kg by means of respiration experimental techniques. The experiments were carried out using the difference method (3 periods feeding basal diet and 3 periods feeding basal diet plus potatoes). The digestibility of energy of the steamed potatoes amounted to 94%, that of organic substances 96% and that of crude protein 77%. The metabolizable energy amounted to 16.1 and the energy deposition to 12.0 MJ/kg DM of steamed potatoes, 74.5% utilization respectively. The results in growing pigs are very similar to the results in adult pigs.

Animal Feed↗
PubMed1993

The effect of routine steam autoclaving on orthodontic pliers.

Five commonly used types of orthodontic plier of similar design, but different manufacture were evaluated for wear and corrosion following a 6-month regime of routine use in a hospital department together with steam autoclaving in a centralized unit. Three different types of manufacture (metal finish) were evaluated: (1) a stainless steel plier; (2) a chrome plated plier; and (3) a cheaper chrome plated plier. Four identical kits for changing archwires were assembled for each of the three manufacture types. A sixth 'plier', always of chrome plated manufacture (group 2) was added to every kit and acted as an additional control. In all, 72 pliers were evaluated by three observers immediately before and after the trial. Visual analogue and rank scales were used to assess corrosion, damage, the efficiency of the plier, etc. Generally, all of the pliers stood up well to a combination of routine clinical use and steam autoclaving; however, the stainless steel pliers appeared to perform the best. It is likely that the most important factor, when setting up this type of sterilizing method for orthodontic instruments, is to establish a careful and meticulous routine for cleaning, lubricating, and steam autoclaving pliers.

Chromium Alloys↗
PubMed1996

Effectiveness of a steam-vacuum sanitizer for reducing Escherichia coli O157:H7 inoculated to beef carcass surface tissue.

A steam-vacuum sanitizer reduced aerobic plate counts associated with bovine faecal contamination from 5.5 log10 cfu cm-2 to 3.0 +/- 0.21 log10 cfu cm-2 on beef carcass short plates. The same beef carcass short plates inoculated with 7.6 +/- 0.09 log10 cfu cm-2 Escherichia coli O157:H7 in faeces, yielded an average residual level of E. coli O157:H7 of 2.1 +/- 0.21 log10 cfu cm-2, after steam-vacuum treatments. This study demonstrates the effectiveness of a steam-vacuum sanitizer for removing E. coli O157:H7 from beef carcasses.

Animals↗
PubMed1966

Disinfection of heat-sensitive material by low-temperature steam and formaldehyde.

Steam under subatmospheric pressure at temperatures below 90 degrees C. rapidly killed nonsporing organisms after air had been removed by a high-vacuum pump. Most bacterial spores were killed but small proportions of the populations were very resistant. The destruction of spores was not logarithmic. The addition of formaldehyde vapour to the steam greatly increased its sterilizing power, with deep penetration into fabrics and destruction of spores. Penetration into wide tubes was good, but was poor in narrow tubes. Most fabrics, plastics, and instruments were unharmed. Low-temperature steam with formaldehyde is probably as efficient a sterilizing agent as ethylene oxide.

Formaldehyde↗
PubMed2001

Possible remediation of dioxin-polluted soil by steam distillation.

2,7-Dichlorodibenzo-p-dioxin (DCDD) was found to evaporate easily with water vapor from a heated solution. Steam distillation was also effective for the removal of DCDD from DCDD-applied soil; its concentration (250 microg/50g soil) in the original soil decreased to less than 5% after steam distillation for only 20 min. Actual dioxin-polluted soil in Tokorozawa City was partially decontaminated using the same method. These results suggest that steam distillation could be a new remedial method for soils contaminated with persistent environmental pollutants, such as dioxins and polychlorinated biphenyls.

Decontamination↗
PubMed2004

Combined steam pretreatment and enzymatic hydrolysis of starch-free wheat fibers.

Steam treatment of an industrial process stream, denoted starch-free wheat fiber, was investigated to improve the formation of monomeric sugars in subsequent enzymatic hydrolysis for further bioconversion into ethanol. The solid fraction in the process stream, derived from a combined starch and ethanol factory, was rich in arabinose (21.1%), xylose (30.1%), and glucose (18.6%), in the form of polysaccharides. Various conditions of steam pretreatment (170-220 degrees C for 5-30 min) were evaluated, and their effect was assessed by enzymatic hydrolysis with 2 g of Celluclast + Ultraflo mixture/100 g of starch-free fiber (SFF) slurry at 5% dry matter (DM). The highest overall sugar yield for the combined steam pretreatment and enzymatic hydrolysis, 52 g/100 g of DM of SFF, corresponding to 74% of the theoretical, was achieved with pretreatment at 190 degrees C for 10 min followed by enzymatic hydrolysis.

Arabinose↗
PubMed2006

Ethanol production from steam-explosion pretreated wheat straw.

Bioconversion of cereal straw to bioethanol is becoming an attractive alternative to conventional fuel ethanol production from grains. In this work, the best operational conditions for steam-explosion pretreatment of wheat straw for ethanol production by a simultaneous saccharification and fermentation process were studied, using diluted acid [H2SO4 0.9% (w/w)] and water as preimpregnation agents. Acid- or water-impregnated biomass was steam-exploded at different temperatures (160-200 degrees C) and residence times (5, 10, and 20 min). Composition of solid and filtrate obtained after pretreatment, enzymatic digestibility and ethanol production of pretreated wheat straw at different experimental conditions was analyzed. The best pretreatment conditions to obtain high conversion yield to ethanol (approx 80% of theoretical) of cellulose-rich residue after steam-explosion were 190 degrees C and 10 min or 200 degrees C and 5 min, in acid-impregnated straw. However, 180 degrees C for 10 min in acid-impregnated biomass provided the highest ethanol yield referred to raw material (140 L/t wheat straw), and sugars recovery yield in the filtrate (300 g/kg wheat straw).

Bioreactors↗
PubMed2000

Cellulase production of Trichoderma reesei Rut C 30 using steam-pretreated spruce. Hydrolytic potential of cellulases on different substrates.

Various techniques are available for the conversion of lignocellulosics to fuel ethanol. During the last decade processes based on enzymatic hydrolysis of cellulose have been investigated more extensively, showing good yield on both hardwood and softwood. The cellulase production of a filamentous fungi, Trichoderma reesei Rut C 30, was examined on carbon sources obtained after steam pretreatment of spruce. These materials were washed fibrous steam-pretreated spruce (SPS), and hemicellulose hydrolysate. The hemicellulose hydrolysate contained, besides water-soluble carbohydrates, lignin and sugar degradation products, which were formed during the pretreatment and proved to be inhibitory to microorganisms. Experiments were performed in a 4-L laboratory fermentor. The hydrolytic capacity of the produced enzyme solutions was compared with two commercially available enzyme preparations, Celluclast and Iogen Cellulase, on SPS, washed SPS, and Solka Floc cellulose powder. There was no significant difference among the different enzymes produced by T. reesei Rut C 30. However, the conversion of cellulose using these enzymes was higher than that obtained with Iogen or Celluclast cellulases using steam-pretreated spruce as substrate.

Cellobiose↗
PubMed2002

Cellulase adsorption and an evaluation of enzyme recycle during hydrolysis of steam-exploded softwood residues.

The sugar yield and enzyme adsorption profile obtained during the hydrolysis of SO2-catalyzed steam-exploded Douglas-fir and posttreated steam-exploded Douglas-fir substrates were determined. After hot alkali peroxide posttreatment, the rates and yield of hydrolysis attained from the posttreated Douglas-fir were significantly higher, even at lower enzyme loadings, than those obtained with the corresponding steam-exploded Douglas-fir. The enzymatic adsorption profiles observed during hydrolysis of the two substrates were significantly different. Ultrafiltration was employed to recover enzyme in solution (supernatant) and reused in subsequent hydrolysis reactions with added, fresh substrate. These recycle findings suggested that the enzyme remained relatively active for three rounds of recycle. It is likely that enzyme recovery and reuse during the hydrolysis of posttreated softwood substrates could lead to reductions in the need for the addition of fresh enzyme during softwood-based bioconversion processes.

Adsorption↗
PubMed1999

Flake density of steam-processed sorghum grain alters performance and sites of digestibility by growing-finishing steers.

The effect of several flake densities (FD) of steam-processed sorghum grain on performance, and site and extent of nutrient digestibilities by steers fed growing and finishing diets was determined. The effectiveness of common laboratory methods of starch availability (enzymatic hydrolysis or gelatinization) to provide target specifications for quality control of steam-flaked grains was also measured. In vitro starch availability of the processed grains increased (P < .05) linearly in response to decreased FD. Flake density was more highly correlated with enzymatic measures than with percentage gelatinization (R2 = .87 to .93 vs .36). Using 140 crossbred beef steers (181 kg initial weight), feedlot performance was determined for 112 d with a growing diet (50% grain), followed by 119 d with a finishing diet (78% grain). Each FD treatment (412, 360, 309, and 257 g/L or 32, 28, 24, and 20 lb/bu) was randomly assigned to five pens of seven steers each. Intake of DM by steers decreased linearly (P < .05) as FD decreased (7 and 13%, respectively, for growing and finishing diets). Decreasing FD reduced linearly (P < .05) ADG in the finishing phase and for the entire 231-d trial. With the growing diet only, feed efficiency and estimated diet NEm and NEg responses to decreasing FD were curvilinear (P < .05), with the 360 g/L (28 lb/bu) flake being most efficient. Electrical energy requirements for processing increased linearly (P < .05) as FD decreased. Using four multi-cannulated crossbred steers (275 kg), starch digestibility increased linearly (P < .05) in the rumen (82 to 91%) and total tract (98.2 to 99.2%) as FD decreased. Digestibilities within the small (74%) and large intestines (62%) were not altered by FD. Decreasing FD increased (P < .05) total CP digestibility, but did not consistently alter fiber digestibility or DE content of the diets. In conclusion, enzymatic laboratory methods to evaluate starch availability in processed grains can be used satisfactorily to establish FD criteria for quality control of the steam-flaking process. The greatest improvements in efficiency, estimated diet NE, and starch and protein digestibilities usually occurred when FD was decreased from 412 to 360 g/L (32 to 28 lb/bu). Based on these measures and processing costs, the optimal FD was 360 g/L (28 lb/bu).

Animal Feed↗