PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Conditioning, Operant”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 541 records · Page 30Linked to original sources
PubMed1985

A survey on operating conditions and quality of commercial frying fats in Hungary.

An extensive survey on commercial frying fats was conducted in Budapest. It was based on sample collection, analysis and questionnaires filled in with each sample. Frying fats and oils were collected from restaurants, fast-food services and public catering facilities. The quality of samples was assessed by determining their polar components. An evaluation of questionnaires containing over 20 questions yielded detailed information on the usage of fats as well as the fryer operators' habits of conducting frying processes and their knowledge on the subject. The survey consisted of two periods. During the first period 252 samples were collected at random. Quality assessment indicated that 53.6% of all samples was of good quality (with concentrations of polar materials below 25%) while the rest were at the discard point or deteriorated. The second part of the survey was aimed at a recheck of the places where fat had been found deteriorated. Second samples were obtained from 53 establishments. The results showed an improvement both in operating conditions and quality of frying fats. Based on the results, the necessity of instructing fryer operators and introducing regulations and routine quality testings of frying fats became obvious.

Cooking↗
PubMedDate not supplied

Protein fouling of virus filtration membranes: effects of membrane orientation and operating conditions.

The capacity of virus filters used in the purification of therapeutic proteins is determined by the rate and extent of membrane fouling. Current virus filtration membranes have a complex multilayer structure that can be used with either the skin-side up or with the skin-side facing away from the feed, but there is currently no quantitative understanding of the effects of membrane orientation or operating conditions on the filtration performance. Experiments were performed using Millipore's Viresolve 180 membrane under both constant pressure and constant flux operation with sulfhydryl-modified BSA used as a model protein. The capacity with the skin-side up was greater during operation with constant flux and at low transmembrane pressures, with the flux decline or pressure rise due primarily to osmotic pressure effects. In contrast, data obtained with the skin-side down showed a slower, steady increase in total resistance with the cumulative filtrate volume, with minimal contribution from osmotic pressure. The capacity with the skin-side down was significantly greater than that with the skin-side up, reflecting the different fouling mechanisms in the different membrane orientations. These results provide important insights for the design and operation of virus filtration membranes.

Membranes, Artificial↗
PubMed1999

Comparison of Bacillus subtilis and Serratia marcescens as protease producers under different operating conditions.

Two microorganisms, Bacillus subtilis and Serratia marcescens, have been selected in order to assess their ability to produce proteases. First, their performances have been studied using three media providing different levels of the main nutrients (complex, semi-defined and defined). The optimal absolute production was obtained in the complex media, while maximum protease activity per cell weight appeared in defined medium for Bacillus and in semi-defined and complex media for Serratia. Then, the effects of applying different environmental conditions to the cells were studied. The two microorganisms were immobilised in calcium alginate beads, protease production by these systems was assessed in the previously tested culture media, and the performances in free and immobilized operating conditions were compared. The richest medium seemed to be the best one in terms of absolute protease production, although the use of semi-defined or defined media could be considered more appropriate, in order to minimise growth of cells leaked from the support, and therefore downstream processing cost. Productivity was slightly higher in free cultures than in immobilized cultures, and retention of enzyme within the alginate beads was detected in the latter, indicating the occurrence of diffusional limitations. In all the cases studied, Serratia marcescens appeared as a better protease producer than B. subtilis, in terms of absolute production. This fact could be related to the different cell growth levels observed for the two microorganisms.

Journal Article↗
PubMed2000

The role of some brain structures in the switching of the descending influences in operantly conditioned rats.

A hypothesis was proposed according to which the switching of descending influences by the corticospinal and corticorubrospinal systems was associated with rubro-olivary projection involvement depending on the context of movement [Kennedy P. R. (1990) Trends Neurosci. 13, 474-479]. Our results confirmed and extended this hypothesis. It was shown that a preliminary transection of the dorsolateral funiculus (containing the rubrospinal tract) accelerated the compensatory rehabilitation process following lesions of the red nucleus and the ventrolateral thalamic nucleus in albino rats with learned instrumental reflexes on equilibrium. A preliminary lesion of the ventrolateral thalamic nucleus considerably hampered the switching process; nevertheless, performance of the reflexes suggested that the switching of cerebellar ascending influences to the cerebral cortex could be completed through other cerebellocortical pathways as well. Comparison of the results of electrolytic and chemical lesions of the red nucleus suggested a similar conclusion. It was established that the conditioning and recovery of already learned instrumental reflexes were impossible after complete neurotoxic destruction of the inferior olive. The data obtained emphasize the role of the inferior olive, ventrolateral thalamic nucleus and red nucleus in the switching of descending influences in operantly motor conditioned rats. Motor deficit and the compensatory rehabilitation process depended on the severity of inferior olive destruction combined with a high transection of the dorsolateral funiculus and a destroyed red nucleus. Long-lasting training improved compensation of motor deficit and stabilized instrumental reflexes to some extent in rats with incomplete destruction of the inferior olive. It has been suggested that these modifications occur because of collateral sprouting in the olivocerebellar system.

Animals↗
PubMed2003

Optimum operation conditions of nitrogen and phosphorus removal by a biofilm-activated-sludge system.

In the biofilm and activated sludge combined system, denitrifying bacteria attached on the fibrous carriers in the anoxic tank, while the sludge containing nitrifying and phosphorus removal bacteria was only recirculated between the aerobic and anaerobic tanks. Therefore, the factors affected and restricted nitrification, denitrification and phosphorus removal in a traditional A/A/O process were resolved. This paper describes the optimum operation conditions for nitrogen and phosphorus removal using this system.

Bacteria, Aerobic↗
PubMed1987

Retention reproducibility of basic drugs in high-performance liquid chromatography on a silica column with a methanol-ammonium nitrate eluent. The effect of the mobile phase and the operating conditions.

The reproducibility of capacity factors and relative capacity factors are compared as methods for recording retentions for the high-performance liquid chromatography of basic drugs on a silica column with methanol-aqueous ammonium nitrate as the eluent. The effects of changing the column temperature and the ionic strength, pH and proportion of organic modifier in the eluent on the retentions and selectivity have been studied. The results suggest that the mobile phase and operating conditions must be closely defined in order to obtain results of adequate reproducibility to develop a data base of retention values for interlaboratory comparisons and/or for the identification of basic drugs.

Chemical Phenomena↗
PubMed1975

The impact of two different reinforcers on conditioned operant heart-rate acceleration and deceleration.

The effects of two types of reinforcers on operant heart-rate acceleration and deceleration conditioning were examined over a number of sessions. The initial use of monetary reinforcement facilitated discriminative pre-trial to trial heart-rate acceleration during sessions utilizing both monetary reinforcement and visual feedback. The initial use of visual feedback did not produce such discriminative control, but the subsequent use of monetary reinforcement resulted in increases in pre-trial and trial heart rate over sessions. No effects due to type of reinforcement were noted for heart-rate deceleration. Increases and decreases in cardiovascular functioning were imposed upon a background of increased skin responding. The cardiovascular responses that developed over sessions appeared to be relatively independent of changes in skin response.

Conditioning, Operant↗
PubMed2001

Out-of-phase operating conditions, a hitherto unknown phenomenon in shaking bioreactors.

One of the important parameters in characterising fermentations of aerobic microorganisms is the specific power consumption. A new method has been introduced which enables the accurate determination of the power consumption in shaking bioreactors. It is based on torque measurements in the drive and the appropriate compensation of the friction losses. Measurements of the power consumption revealed the phenomenon of the liquid being 'out-of-phase' for the first time for shaking bioreactors. This occurs at certain operating conditions and is characterised by an increasing amount of liquid not following the rotating movement of the shaker table, thus reducing the specific power consumption, mixing and the gas/liquid mass transfer. With respect to this, different hydrodynamic cases have to be distinguished. All these cases have in common, however, that the probability of 'out-of-phase' conditions increases with lower shaking diameters, lower filling volumes, larger number and sizes of baffles and higher viscosity. For unbaffled flasks with a nominal volume </=1l the 'out-of-phase' phenomenon is described in the form of a newly defined non-dimensional Phase number (Ph). To avoid the (unidentified) development of a screening project in unfavourable directions or even its complete failure, researchers must be aware of the 'out-of-phase' phenomenon. The experimental protocols have to be carefully selected so that the occurrence of such unwanted hydrodynamic conditions is not possible under all experimental circumstances.

Journal Article↗
PubMed2001

Influence of binder properties, method of addition, powder type and operating conditions on fluid-bed melt granulation and resulting tablet properties.

The aim of the study was to investigate melt granulation in a laboratory scale fluid-bed granulator with respect to granule growth, granule properties and resulting tablet properties. The parameters investigated were method of addition of PEG (spray-on or addition as flakes), binder concentration, PEG type (3000, 4000 and 6000, sprayed-on), size (PEG 4000, added as three different sized flakes), powder type (two different sized lactose types and corn starch) and operating conditions (volume air flow and heating temperature). Addition of binder as flakes led to layering as a growth mechanism when the size of the flakes was high. Coalescence occurred when the size was low. Coalescence also occurred when spraying was the method of addition. Due to the greater viscosity of the PEG 6000 melt it produced bigger granules than 3000 or 4000. The influence of volume air flow was moderate and the influence of heating temperature in the range of 70-90 degrees C was very low with both methods of addition. The disintegration time of tablets from granules where PEG was added as flakes was shorter than from granules where PEG was sprayed-on. The latter method of binder addition led to tablets which did not disintegrate but eroded. This was apparently caused by formation of a binder matrix, which could not be destroyed by the disintegrant.

Drug Compounding↗
PubMed2006

Extraction of lycopene from tomato skin with supercritical carbon dioxide: effect of operating conditions and solubility analysis.

Supercritical carbon dioxide (SCCO2) extraction of lycopene from waste tomato skins was investigated. The experiments were carried out at pressures and temperatures ranging from 20 to 50 MPa and 313 to 373 K, respectively, without any modifiers. The flow rate of CO2 was maintained at 2.5 mL/min for 330 min extraction time. Solvent flow rate effect was examined for CO2 flow rates from 1.5 to 4.5 mL/min. The extracts were analyzed by high-performance liquid chromatography and UV-visible spectroscopy. The results showed that with optimized operating conditions, the maximum yield of lycopene (1.18 mg of lycopene/g of sample) was obtained at 40 MPa, 373 K, and 2.5 mL of CO2/min. Chromatographic analysis indicated that lycopene was extracted from tomato skin with negligible degradation at the optimum conditions and the amount extracted represented more than 94% of the total carotenoid content of the sample. The solubility of lycopene was modeled by use of the Chrastil equation.

Carbon Dioxide↗
PubMed2001

Biofilters--the influence of different filter materials and different operating conditions on the reduction efficiency.

A series of biofilter materials were tested for performance efficiency in treating ventilation air from pig sheds. Two different phases were conducted. In phase A five different biofilter materials were tested with the aim of selecting the best material regarding the odor reduction and over all efficiency. In conclusion of phase A, biochips, a new filter material, was selected due to its high average odor reduction (81%) in combination with a very low flow resistance (less than 30 Pa for filter volume loads of 600 m3 h(-1) m(-3)). In phase B, biochips and coconut fiber peat were tested under different operating conditions. Biofilters number 3 and 4 each with down-flow air supply could realize a higher average odor reduction than biofilter 5 with up-flow air supply. All three filter materials had the same moisture, however the two biofilters with down-flow air supply showed a more homogenous moisture distribution but they also used approximately three times more water than biofilter 5. Like in phase A the specific odor cleaning efficiency was mainly influenced by the specific odor loading rate and showed only slight differences between the five biofilters differing in bulk layer height (0.5 m and 1.0 m) and air supply mode. All in all the investigation showed that the efficiency of biofilters can be optimized by using an new filter material and a appropiate operating mode.

Air Movements↗
PubMed1987

Long-term increases in dentate granule cell responsivity accompany operant conditioning.

The efficacy of synaptic transmission from the perforant path (PP) to the granule cells in the dentate gyrus (DG) of freely moving rats was monitored electrophysiologically over the course of training in an appetitively motivated, discriminated operant paradigm. Every day, 22 hr after behavioral sessions, evoked potentials were recorded from the DG following stimulation of the PP over range of current intensities and the amplitudes of the population spikes were measured. Behavioral conditions involved training in an operant conditioning paradigm or a session of free-feeding. Significant increases in population spike amplitudes were observed over the 8 d of training, but not over the 8 d of free-feeding. This training-induced increase in granule cell responsivity persisted for at least 10 d following the cessation of behavioral trials and was in many ways comparable to long-term potentiation (LTP), subsequently observed in these same rats 24 hr after tetanic stimulation. These data confirm and extend previous reports of synaptic enhancements following conditioning and suggest that such increases in synaptic efficacy may encode some aspect of learning.

Animals↗
PubMed1992

The effect of graded activity on patients with subacute low back pain: a randomized prospective clinical study with an operant-conditioning behavioral approach.

The aim of this study was to determine whether graded activity restored occupational function in industrial blue-collar workers who were sick-listed for 8 weeks because of subacute, nonspecific, mechanical low back pain (LBP). Patients with LBP, who had been examined by an orthopedic surgeon and a social worker, were randomly assigned to either an activity group (n = 51) or a control group (n = 52). Patients with defined orthopedic, medical, or psychiatric diagnoses were excluded before randomization. The graded activity program consisted of four parts: (1) measurements of functional capacity; (2) a work-place visit; (3) back school education; and (4) an individual, submaximal, gradually increased exercise program, with an operant-conditioning behavioral approach, based on the results of the tests and the demands of the patient's work. Records of the amount of sick leave taken over a 3-year period (ie, the 1-year periods before, during, and after intervention) were obtained from each patient's Social Insurance Office. The patients in the activity group returned to work significantly earlier than did the patients in the control group. The median number of physical therapist appointments before return to work was 5, and the average number of appointments was 10.7 (SD = 12.3). The average duration of sick leave attributable to LBP during the second follow-up year was 12.1 weeks (SD = 18.4) in the activity group and 19.6 weeks (SD = 20.7) in the control group. Four patients in the control group and 1 patient in the activity group received permanent disability pensions. The graded activity program made the patients occupationally functional again, as measured by return to work and significantly reduced long-term sick leave.

Absenteeism↗
PubMed2003

Influence of operational conditions on biofilm specific activity of an anaerobic fluidized bed reactor.

A key parameter in water and wastewater treatment technology is the biomass activity in terms of substrate removal ability. The effects of organic load rate and percentage of bed expansion on biofilm specific methanogenic activity were determined in an anaerobic fluidized bed reactor treating wine-distillery wastes in the thermophilic range (55 degrees C). The proposed activity tests are highly reproducible: an experiment with three identical tests has shown that the standard deviation with respect to the mean values is less than 3%. Specific tests are applied to measure the maximum methanogenic activities of the biomass carrier in lab-scale anaerobic biofilm reactors. These tests have been successfully applied for monitoring the support colonization process and the evolution of biofilm activity in reactors, anaerobic filter and fluidized bed, with different operating conditions. The results show a dependence between the percentage of bed expansion and the specific activity of methanogenic microbiote on biofilm. There is a relationship between the percentage of bed expansion, the sheer stress on the biofilm and the hydrodynamic conditions in the system. Initial biofilm detachment can be compensated with the increase of biomass and of its activity due to the reduction of the substrate diffusional limitations to the microorganism growth inside the support pores.

Bacteria, Anaerobic↗
PubMed2005

Optimization of operating conditions for the determination of perchlorate in biological samples using preconcentration/preelution ion chromatography.

Perchlorate originates as a contaminant in the environment from the use of salts in the manufacture of solid rocket fuels and munitions. Monitoring potential perchlorate contamination in the environment is of interest, however, very few analytical methods have been developed for perchlorate determination in biological samples. Analysis of complex samples by ion chromatography is complicated by matrix components that can interfere with perchlorate determination. However, a recently developed preconcentration/preelution (PC/PE) ion chromatography method has demonstrated the capability to analyze certain complex samples such as high salinity water, milk, and hydroponic fertilizers. The ability of this method to reduce sample background and lower detection limits in ion chromatography for various biological samples was evaluated in this study. The PC/PE method was applicable to the analysis of kidneys, livers, zebrafish, quail eggs, lettuce, and urine. Optimal operating conditions were determined for each matrix. Ranges of optimal wash volumes were shorter when 15 mM NaOH prewash solutions were used compared with 10mM and good recovery was achieved for most matrices with an injection period > or =60s. Prewash solution concentration did not appear to significantly affect matrix background. The PC/PE method was capable of reducing sample background when compared to EPA Method 314.0, which resulted in detection limits, with the exception of zebrafish and urine, that were two-fold lower than those achieved with EPA Method 314.0.

Animals↗
PubMed2001

Reverse osmosis filtration for space mission wastewater: membrane properties and operating conditions.

Reverse osmosis (RO) is a compact process that has potential for the removal of ionic and organic pollutants for recycling space mission wastewater. Seven candidate RO membranes were compared using a batch stirred cell to determine the membrane flux and the solute rejection for synthetic space mission wastewaters. Even though the urea molecule is larger than ions such as Na+, Cl-, and NH4+, the rejection of urea is lower. This indicates that the chemical interaction between solutes and the membrane is more important than the size exclusion effect. Low pressure reverse osmosis (LPRO) membranes appear to be most desirable because of their high permeate flux and rejection. Solute rejection is dependent on the shear rate, indicating the importance of concentration polarization. A simple transport model based on the solution-diffusion model incorporating concentration polarization is used to interpret the experimental results and predict rejection over a range of operating conditions. Grant numbers: NAG 9-1053.

Creatine↗
PubMed2005

Treatment of chlorinated solvents by TiO2 photocatalysis and photo-Fenton: influence of operating conditions in a solar pilot plant.

Titanium dioxide photocatalysis (using 20 0mg l(-1) of TiO2), under aerobic and anaerobic conditions, and photo-Fenton (2 and 56 mg l(-1) iron) were applied to the treatment of different NBCS (non-biodegradable chlorinated solvents), such as dichloroethane, dichloromethane and trichloromethane dissolved in water at 50 mg l(-1). All the tests were performed in a 35-l solar pilot plant with compound parabolic collectors (CPCs) under natural illumination. The two solar treatments were compared with attention to chloride release and TOC mineralisation, as the main parameters. Photo-Fenton was found to be the more appropriate treatment for these compounds, assuming volatilisation as a drawback of photocatalytic degradation of NBCS dissolved in water. In this context, several operating parameters related to NBCS degradation, e.g., treatment time, temperature, hydrogen peroxide consumption and volatility of parent compounds are discussed. The correct choice of operating conditions can very often diminish the problem of volatilisation during treatment.

Catalysis↗