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At least 613 records · Page 34Linked to original sources
PubMed2005

Changes in bacterial community structure correlate with initial operating conditions of a field-scale denitrifying fluidized bed reactor.

High levels of nitrate are present in groundwater migrating from the former waste disposal ponds at the Y-12 National Security Complex in Oak Ridge, TN. A field-scale denitrifying fluidized bed reactor (FBR) was designed, constructed, and operated with ethanol as an electron donor for the removal of nitrate. After inoculation, biofilms developed on the granular activated carbon particles. Changes in the bacterial community of the FBR were evaluated with clone libraries (n = 500 partial sequences) of the small-subunit rRNA gene for samples taken over a 4-month start-up period. Early phases of start-up operation were characterized by a period of selection, followed by low diversity and predominance by Azoarcus-like sequences. Possible explanations were high pH and nutrient limitations. After amelioration of these conditions, diversification increased rapidly, with the appearance of Dechloromonas, Pseudomonas, and Hydrogenophaga sequences. Changes in NO3, SO4, and pH also likely contributed to shifts in community composition. The detection of sulfate-reducing-bacteria-like sequences closely related to Desulfovibrio and Desulfuromonas in the FBR have important implications for downstream applications at the field site.

Bacteria↗
PubMedDate not supplied

Air Sampling System for use in monitoring viable and non-viable particulate air quality under dynamic operating conditions of blow/fill/seal processing.

An Air Sampling Link (ASL), employed in conjunction with an Air Sampling Device (ASD) or a laser particle counter, has been developed for sampling flowing air for viable and non-viable particulate analyses. Typically, the ASL could be used to sample filtered air supplied to an air shower of a Blow/Fill/Seal machine operating in the dynamic state. The ASL allows sample volumes of air to be taken from flowing air without significant loss from the sample flow of airborne particles possessing aerodynamic sizes relevant to those found in practice. The link has no moving parts, is steam sterilizable in-situ, and allows for the taking of continuous samples of air without the need for intervention into the 'critical zone' of the filling machine. This article describes (i) the design criteria for the ASL and the ASD, (ii) the rationale underlying the concept of the ASL design, (iii) the collection performance of the ASL against that of a conventional sampling arrangement, and (iv) a functionality assessment of the ASL-based sampling system installed on a Rommelag style 305 B/F/S machine over a seven week period.

Air Microbiology↗
PubMed2005

The effect of operational conditions on the performance of UASB reactors for domestic wastewater treatment.

In this investigation, the performance of Upflow Anaerobic Sludge Blanket (UASB) reactors treating municipal wastewater was evaluated on the basis of: (i) COD removal efficiency, (ii) effluent variability, and (iii) pH stability. The experiments were performed using 8 pilot-scale UASB reactors (120 L) from which some of them were operated with different influent COD (CODInf ranging from 92 to 816 mg/L) and some at different hydraulic retention time (HRT ranging from 1 to 6 h). The results show that decreasing the CODInf, or lowering the HRT, leads to decreased efficiencies and increased effluent variability. During this experiment, the reactors could treat efficiently sewage with concentration as low as 200 mg COD/L. They could also be operated satisfactorily at an HRT as low as 2 hours, without problems of operational stability. The maximum COD removal efficiency can be achieved at CODInf exceeding 300 mg/L and HRT of 6h.

Bacteria, Anaerobic↗
PubMed1986

Clearance of a dialyzer under varying operating conditions.

The clearance of a dialyzer at zero ultrafiltration and zero inlet concentration in the dialysate was studied for varying dialysate flows. It was found that a practically feasible limit can be set to the dialysate flow, above which the gain in clearance is minimal or negligible, resulting more in a waste of dialysate than in increased mass transport. The results suggest a more economical operation of dialyzers, which is of general interest, as well as of special interest in areas where no on-line dialysate preparation is used (e.g., because of unreliable water supplies).

Dialysis↗
PubMed2003

Enteric coating of soft gelatin capsules by spouted bed: effect of operating conditions on coating efficiency and on product quality.

The present study was conducted in order to analyze the viability of the spouted bed process for application of a gastric-resistant coating to soft gelatin capsules. The variables investigated were: included angle of conical base, (gamma), the relation between the feed mass flow rate of the coating suspension and the feed mass flow rate of spouting gas (W(s)/W(g)); the ratio between the flow rate of the spouting gas and the flow rate at minimum spouting condition (Q/Q(ms)); the mass of capsules in the bed (M(0)), and the capsule's size. The product quality was measured by disintegration tests, traction x deformation tests, image analysis and by the evaluation of the coating mass distribution and shape factor variation during the coating operation. The experiments were performed in a spouted bed with a column diameter of 200 mm and included a conical base angle of 40 degrees. The best coating efficiency values were obtained for M(0)=300 g. Coating efficiency tended to increase with increasing W(s)/W(g) ratio. Disintegration tests showed that the gastric-resistant effect was obtained with a coating mass of 3.86 mg/cm(2). The shape factor increase during the coating operation. The capsule's coating mass distribution tended to maintain the original distribution.

Capsules↗
PubMed2004

Operational conditions affecting the vaccination of older adults.

BACKGROUND: The content and context of the process of vaccinating older adults against influenza in outpatient settings has not been adequately described. Failure to appreciate the causal antecedents or precursors to the act of provider recommendation may explain why so many efficacious interventions identified by the U.S. Task Force on Community Preventive Services fail to be routinely implemented and why influenza immunization rates have remained static over the past decade. METHODS: This study used critical path analysis from data collected during standardized workflow observations of patients more than 50 years of age from a convenience sample of 16 ambulatory care settings in San Diego, California; Rochester, New York; and Albuquerque, New Mexico. Observations were made from October 23, 2001 to January 31, 2002. RESULTS: In this study, 62% (151/243) of patients observed during scheduled extended visits received influenza vaccinations. When operational, temporal, and clinical factors are examined altogether through critical path analysis, a model of seven critical organizational support, temporal, and clinical activities emerges that is able to predict 93% of the immunizations. Variation from the model predicts 73% of the missed opportunities. CONCLUSIONS: Vaccination of adults should not be seen as simply an incremental activity added to the general health encounter. Assuring a high rate of vaccination requires adequate time and operational support. Provider-patient discussion is more productively viewed as the culmination of the immunization process, not the beginning. Finally, this study indicates the potential need to identify and compare processes of care associated with other specific preventive services.

Aged↗
PubMed2001

The effect of operating conditions on the performance of soil slurry-SBRs.

Biological treatment of a silty clay loam with aged diesel fuel contamination was conducted in 8 L Soil Slurry-Sequencing Batch Reactors (SS-SBRs). The purpose was to monitor slurry conditions and evaluate reactor performance for varying solids concentration (5%, 25%, 40%, 50%), mixing speed (300 rpm, 700 rpm, 1200 rpm), retention time (8 d, 10 d, 20 d), and volume replaced per cycle (10%, 50%, 90%). Diesel fuel was measured in slurry and in filtered aqueous samples. Oxygen uptake rate (OUR) was monitored. Aggregate size was measured with sieve analyses. Biosurfactant production was quantified with surface tension measurements. Increasing solids concentration and decreasing mixing speed resulted in increased aggregate size, which in turn increased effluent diesel fuel concentrations. Diesel fuel removal was unaffected by retention time and volume replaced per cycle. Biosurfactant production occurred with all operating strategies. Foam thickness was related to surfactant concentration and mixing speed. OUR, surfactant concentration, and foam thickness increased with increasing diesel fuel added per cycle.

Bioreactors↗
PubMed2007

[Pharmacovigilance implementation and operational conditions in the pharmaceutical industry in São Paulo State, Brazil].

UNLABELLED: The development of new drugs and limitations of clinical trials have increased the likelihood of adverse drug events. Pharmacovigilance is essential to detect and evaluate adverse drug events, thereby reducing risks and avoiding excessive public health costs. This study focused on the pharmacovigilance programs in the pharmaceutical industry in São Paulo State, Brazil. Data were collected through questionnaires sent electronically to 105 companies, 41.9% of which responded. The main reason for implementing pharmacovigilance programs was to comply with legal requirements, while the main justification for its absence was production limited to herbal remedies, officinal products, and supplements. The article discusses the obstacles to program implementation, resources used, and characteristics of several such programs. CONCLUSIONS: (a) standardization is the reason for the increasing number of programs and reports, but more specific guidelines are needed; (b) results depend on multi-sector involvement; (c) customer service centers are an important source of reports; and (d) operation of the service requires only modest human and material resources.

Adverse Drug Reaction Reporting Systems↗
PubMed2003

The sensitivity of fixed-bed biological perchlorate removal to changes in operating conditions and water quality characteristics.

Flow rate, electron donor addition, and biomass control were evaluated in order to optimize perchlorate (ClO4-) removal from drinking water using biologically active carbon (BAC) filtration. Influent dissolved oxygen (DO) was lowered from ambient conditions to approximately 2.5 mg/L for all experiments using a nitrogen sparge. When influent nitrate concentration was 0-2.0 mg/L, 1.6-2.8 mg/L as carbon of acetate or ethanol was required to achieve and sustain the complete removal of 50 microg/L perchlorate in a BAC filter. Most or all of the exogenous acetate and ethanol was removed during biofiltration. When a 72-h electron donor feed failure was simulated, a maximum perchlorate breakthrough of 18 microg/L was observed and, once electron donor was reapplied, 9 days were required to reestablish complete perchlorate removal. During a 24-h electron donor feed failure simulation, the maximum effluent perchlorate concentration detected was 6.7 microg/L. Within 24 h of reactivating the electron donor, the filter regained its capacity to consistently remove 50 microg/L perchlorate to below detection. Although biomass growth diminished the filter's ability to consistently remove perchlorate, a cleaning procedure immediately restored stable, complete perchlorate removal. This cleaning procedure was required approximately every 50 days (4800 bed volumes) when influent DO concentration was 2.5 mg/L. Empty-bed contact time (EBCT) experiments showed that 80% perchlorate removal was achieved using a 5-min EBCT, and complete perchlorate removal was observed for an EBCT of 9 min. It was also demonstrated that BAC filtration consistently removed perchlorate to below detection for influent perchlorate concentrations ranging from 10 to 300 microg/L, influent sulfate concentrations between 0 and 220 mg/L, influent pH values of 6.5-9.0, and operating temperatures of 5-22 degrees C.

Biomass↗
PubMed1998

Optimized enzymatic synthesis of methyl benzoate in organic medium. Operating conditions and impact of different factors on kinetics

Enzyme-catalyzed synthesis of methyl benzoate is reported. It is the first example of direct esterification of benzoic acid which provides good yields. The reaction was performed in a heterogeneous medium by Candida rugosa lipase powder suspended in a hexane/toluene mixture. The impact of some factors was examined. Benzoic acid does not inhibit the lipase until 100 mM. Above 90 mM, methanol inhibits the enzyme. This inhibition is partially eliminated by increasing benzoic acid concentration. Below 90 mM, methanol mainly interacts with the water adsorbed on the biocatalyst. A minimum water content is necessary to activate the biocatalyst. Water must be provided proportionally to the lipase content. Toluene, necessary for benzoic acid solubilization, also acts negatively on reaction kinetics. This is attributed to a modification of benzoic acid partition between the biocatalytic and the organic phases. Copyright 1998 John Wiley & Sons, Inc.

Journal Article↗
PubMed1999

Optimization of protein separation by continuous-flow electrophoresis: influence of the operating conditions and the chamber thickness.

The separation of protein by continuous-flow electrophoresis is disturbed by a number of effects which cause spreading of the protein streams with a loss of resolution. Two numerical models have been used to describe the coupling between the various spreading phenomena. A simple model takes into account molecular diffusion, electroosmosis and residence time gradients; the main model differs from the simple one by taking account of electrohydrodynamics. The influence of the separation chamber thickness, the radius of the sample filament, the field strength, and the residence time is explored. The simulations show that each dispersive effect has its own range of predominance, so that an optimum is found for the thickness of the separation chamber.

Animals↗
PubMed2001

Operating conditions that affect the resistance of lactic acid bacteria to freezing and frozen storage.

Thermophilic lactic acid bacteria exhibit different survival rates during freezing and frozen storage, depending on the processing conditions. We used a Plackett and Burman experimental design to study the effects of 13 experimental factors, at two levels, on the resistance of Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus to freezing and frozen storage. The resistance was evaluated by quantifying the decrease of acidification activity during freezing and throughout 8 weeks of storage. Acidification activity after freezing and frozen storage was affected by 12 experimental factors. Only the thawing temperature did not show any significant effect. S. thermophilus was more resistant than L. bulgaricus and the cryoprotective effect of glycerol during freezing and storage was confirmed. The temperature and duration of the cryoprotection step influenced acidification activity following the freezing step: the lower the temperature and the shorter the duration, the higher the activity. Acidification activity after storage was affected by several experimental factors involved in the fermentation stage: use of NaOH instead of NH4OH for pH control, addition of Tween 80 in the culture medium, and faster cooling led to better cryotolerance. Resistance to freezing and frozen storage was improved by using a high freezing rate and a low storage temperature. Finally, this study revealed that the conditions under which lactic acid bacteria are prepared should be well controlled to improve their preservation and to limit the variability between batches and between species.

Cryopreservation↗
PubMed2000

Pathologic and post-operative conditions of the plantar fascia: review of MR imaging appearances.

Magnetic resonance (MR) imaging has emerged as an important noninvasive diagnostic imaging technique for assessment of foot pathology. This modality, owing to its multiplanar imaging capability and inherent superiority in contrast, has been shown to be more accurate and sensitive for detection of plantar fascia pathology than any other imaging method. One of the most important and recognizable causes of heel pain is plantar fasciitis. With the exception of plantar fasciitis, there has been little emphasis on imaging other conditions that affect this important structure. The objective of this review is to demonstrate, from a perspective of MR imaging, the many different pathologic conditions that affect the plantar fascia. Included in this review will be a discussion of normal anatomy as well as entities such as acute plantar fasciitis, chronic plantar fasciitis, traumatic rupture, normal post-surgical changes, pathologic post-fasciotomy conditions, infection, and fibromatosis.

Ankle Joint↗
PubMed2005

Characterisation of operation conditions and online monitoring of physiological culture parameters in shaken 24-well microtiter plates.

A new online monitoring technique to measure the physiological parameters, dissolved oxygen (DO) and pH of microbial cultures in continuously shaken 24-well microtiter plates (MTP) is introduced. The new technology is based on immobilised fluorophores at the bottom of standard 24-well MTPs. The sensor MTP is installed in a sensor dish reader, which can be fixed on an orbital shaker. This approach allows real online measurements of physiological parameters during continuous shaking of cultures without interrupting mixing and mass transfer like currently available technologies do. The oxygen transfer conditions at one constant shaking frequency (250 1/min) and diameter (25 mm) was examined with the chemical sulphite oxidation method. Varied filling volumes (600-1,200 microL) of Escherichia coli cultures demonstrated the importance of sufficient oxygen transfer to the culture. Cultures with higher filling volumes were subjected to an oxygen limitation, which influenced the cell metabolism and prolongated the cultivation time. The effects could be clearly monitored by online DO and pH measurements. A further study of different media in an E. coli fermentation elucidated the different growth behaviour in response to the medium composition. The MTP fermentations correlated very well with parallel fermentations in shake flasks. The new technique gives valuable new insights into biological processes at a very small scale, thus enabling parallel experimentation and shorter development times in bioprocessing.

Cell Culture Techniques↗