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PubMed2006

The dynamic adsorption characteristics of phenol by granular activated carbon.

The objective of the present work is to determine the operating conditions of an activated carbon filter, based on the characteristics of breakthrough curves. For this we apply the technical developed by Mickaels for the ionic exchange and applied by Luchkis for the adsorption, and which is the mass transfer zone. To reach our goal, an evaluation of the operating conditions (height of the bed, flow and concentration of effluent) on the characteristics of the mass transfer zone was made and an explanation of the mechanism of adsorption was given. Thereafter a modeling of the experimental results was done.

Adsorption↗

PubMed1999

Remifentanil vs. fentanyl during interventional rigid bronchoscopy under general anaesthesia and spontaneous assisted ventilation.

The treatment of tracheo-bronchial diseases with rigid bronchoscopy requires general anaesthesia without tracheal intubation. Spontaneous assisted ventilation is a safe modality of ventilation. In this study the use of remifentanil and fentanyl is compared during rigid bronchoscopy with spontaneous assisted ventilation. Ninety high-risk patients received fentanyl or remifentanil with propofol for general anaesthesia. During the maintenance fentanyl was delivered at 6.1 +/- 4.6 micrograms kg-1 h-1 and remifentanil at 0.15 +/- 0.07 microgram kg-1 min-1. The same degree of intra-operative respiratory acidosis with similar good operating conditions resulted in both groups. Patients treated with remifentanil recovered more quickly compared with those in the fentanyl group (3.8 +/- 2 vs. 10.4 +/- 9.2 min, P < 0.001). In conclusion, the use of remifentanil during rigid bronchoscopy under general anaesthesia with spontaneous assisted ventilation is safe and assures good operating conditions. Moreover, remifentanil permits a more rapid recovery than fentanyl. The dose of remifentanil is higher than previously described for spontaneously breathing patients.

Anesthesia, General↗

PubMed2006

Separation of phosphatidylcholine from soybean phospholipids by simulated moving bed.

A simulated moving bed (SMB), equipped with eight silica-gel columns, was used to separate phosphatidylcholine (PC) from soybean phospholipids. The effects of flow rate in Sections 2 (Q(2)) and 3 (Q(3)), switching time, feed flow rate and feed concentration on the operating performance parameters: purity, recovery, productivity and desorbent consumption were studied. Operating conditions leading to more than 90% purity in both outlet streams have been identified, together with those achieving optimal performance. Regions leading to complete separation are observed and explained theoretically. As the mass-transfer effect was not considered, the triangle theory only gives initial guesses for the optimal operating conditions.

Chemical Fractionation↗

PubMed1998

Multiplicity and stability analysis of microorganisms in continuous culture: effects of metabolic overflow and growth inhibition

Metabolic overflow (enhanced uptake of substrate and secretion of intermediates) is a phenomenon often observed for cells grown under substrate excess. Growth inhibition by substrate and/or product is also normally found for this kind of culture. An effort is made in this work to analyze the dynamic behavior of a continuous culture subject to metabolic overflow and growth inhibition by substrate and/or product. Analysis of a model system shows that in a certain range of operating conditions three nonwashout steady state solutions are possible. Local stability analysis indicates that only two of them are stable thus leading to multiplicity and hysteresis. Further analysis of the intrinsic effects of different terms describing the metabolic overflow and growth inhibitions reveals that for the model system and the parameters considered, the combined effects of product inhibition and an enhanced formation rate of product under substrate excess cause the multiplicity and hysteresis. Growth inhibition by substrate and/or an enhanced substrate uptake appear not to be necessary conditions. The combined effects of enhanced product formation and product inhibition can also lead to unusual dynamic behavior such as a prolonged time period to reach a steady state, oscillatory transition from one steady state to another, and sustained oscillations. Using the occurrence of multiplicity and oscillation as criteria, the operating regime of a continuous culture can be divided into four domains: one with multiplicity and oscillation, one with unique steady state but possible oscillatory behavior, the other two with unique and stable steady state. The model predictions are in accordance with recent experimental results. The results presented in this work may be used as guidelines for choosing proper operating conditions of similar culture systems to avoid undesired instability and multiplicity. Copyright 1998 John Wiley & Sons, Inc.

Journal Article↗

PubMedDate not supplied

Local anaesthesia for vitreoretinal surgery: an audit of patient and surgical experience.

PURPOSE: Local anaesthesia for vitreoretinal surgery is little used as these procedures are deemed to be too long and uncomfortable for patients to tolerate. In this unit anterior intraconal local anaesthesia is used for most routine surgery. We undertook an audit to ensure that surgical standards and patient acceptability were not compromised. METHODS: A prospective observational audit was performed. Audit data included: Grade of anaesthetist and surgeon; details of anaesthetic and operation; compliance of patient; operating conditions and pain scores. Anaesthesia was provided with a combined peribulbar and intraconal anaesthetic, using bicarbonate buffered lignocaine and bupivacaine 50:50 mixture. RESULTS: 135 (76%) had local anaesthesia alone, 13 (7%) had local anaesthesia with sedation and 29 (16%) had general anaesthesia. 96.4% of patients were compliant and 98.8% of operating conditions were good or excellent. The mean perioperative pain score was 0.1 (range of 0-1), 97% said they would choose local anaesthesia again. CONCLUSIONS: LA for vitreoretinal surgery is a useful and flexible method of anaesthesia, which has been shown to have excellent patient tolerance.

Adult↗

PubMed2003

Hydrogen peroxide lifetime as an indicator of the efficiency of 3-chlorophenol Fenton's and Fenton-like oxidation in soils.

In this work the possibility of using the hydrogen peroxide lifetime as indicator of the oxidation efficiency of Fenton's and Fenton-like processes for soil treatment was explored. A reactivity scale, in terms of the oxidizing power in the different tested operating conditions (pH, iron sulfate concentration and stabilizer concentration) was built for each soil as a function of the hydrogen peroxide lifetime. Its validity was then confirmed through 3-chlorophenol Fenton's and Fenton-like slurry-phase oxidation experiments. The proposed reactivity scale proved to be effective for comparing the different operating conditions for the same soil, but failed when used to compare the oxidation performances for different soils, since the different adsorptive behavior of the tested soils may have influenced the contaminant removal rate.

Chlorophenols↗

PubMed2004

Propofol decreases waste anesthetic gas exposure during pediatric bronchoscopy.

OBJECTIVE: This study compared the anesthetic gas exposure and operating conditions during insufflation anesthesia with halothane-alone versus halothane-propofol in children undergoing direct laryngobronchoscopy. STUDY DESIGN: Forty-six children were enrolled in this randomized prospective study, with institutional review board approval and informed consent. METHODS: All children were anesthetized by halothane mask induction and anesthesia was maintained using spontaneous ventilation with insufflation. No muscle relaxants or opioids were used. In the halothane group, halothane was titrated as needed. In the propofol group, halothane was decreased to 1% inspired concentration and the propofol was titrated as needed to maintain spontaneous ventilation and a still patient. Trace anesthetic gases, hemodynamic stability, and operating conditions were measured. RESULTS: The groups were similar in age, weight, and bronchoscopy time. There was significantly less gas exposure in the propofol group (25 +/- 33 parts per million) versus the halothane group (66 +/- 97 ppm; P <.02). There was a trend toward earlier emergence in the halothane group (33 +/- 13 minutes) versus the propofol group (41 +/- 17 minutes). Postoperative stridor was common, occurring in 30% of children. CONCLUSIONS: Insufflation anesthesia with spontaneous respiration provides excellent surgical conditions for laryngobronchoscopy. The addition of propofol resulted in fewer airway complications (P =.047). Although the addition of propofol significantly decreased anesthetic gas exposure in the operating room, both techniques resulted in operating room pollution that exceeded the maximum levels of 2 ppm per hour recommended by the US National Institute for Occupational Safety and Health (NIOSH).

Air Pollution, Indoor↗

PubMed1994

Addition of atracurium to lidocaine for intravenous regional anaesthesia.

This study was undertaken to examine the possible clinical advantages of using muscle relaxant with intravenous regional anaesthesia, (IVRA). Forty unpremedicated adult patients undergoing hand surgery were randomly allocated to receive either 40 ml 0.5% lidocaine or 40 ml 0.5% lidocaine with 2 mg of atracurium. The atracurium group of patients had a significantly greater degree of muscle relaxation, easier reduction of fractures, and better operative conditions (P < 0.01). Less pain was also reported during surgery (P < 0.025), and 5 and 15 min after release of the tourniquet (P < 0.01). Clinically, there was no difference in the speed of onset of block between the two groups. It is concluded that the addition of atracurium to lidocaine improves the operating condition during IVRA with less pain during and after surgery.

Adult↗

PubMed2000

Development of spray-dried acetaminophen microparticles using experimental designs.

Experimental factorial designs were built to investigate the effects of five parameters on production yields and moisture contents of spray-dried products. These factors concerned both the solution feed (drug concentration, colloidal silica concentration and polymer/drug ratio) and the spray dryer (inlet temperature and feed rate). Three formulations containing cellulose derivatives and acetaminophen were tested. The aim of the study was to optimize the operating conditions to maximize production yields while minimizing moisture contents. First screening experiments consisting of fractional factorial designs revealed the most significant factors to be inlet temperature, feed rate and their interaction for both formulations containing sodium carboxymethylcellulose and feed rate and colloidal silica concentration for the formulation containing microcrystalline cellulose. Then, the optimal operating conditions were estimated by response surface methodology. Central rotational composite designs showed quadratic models were adequate. New assays were carried out using these last conditions to evaluate both the repeatability and reproducibility of the spray-drying technique. Yields above 80% and moisture content of approximately 1% were reached. The characterization of microparticles revealed the poor flowability of the spray-dried products due to significant cohesiveness and very small size (less than 55 microm).

Acetaminophen↗

PubMed2005

Central neural blocks: a quality assessment of anaesthesia in gynaecological surgeries.

Quality of anaesthetic care can be improved only after identifying the factors contributing to patients' discomforts and dissatisfaction. The purpose of this prospective observational study was to assess the quality of central neural blocks in terms of physiological alterations and undesired events and to find out modifiable factors associated with patients' discomforts and dissatisfaction. Total 204 female patients (ASA I and II) undergoing gynaecological surgeries received either of the subarachnoid block (SAB), combined spinal epidural anaesthesia (CSEA) or lumbar epidural anaesthesia (LEA) depending on the nature of the procedure. Intra-operative and immediate post-operative physiologic alterations and undesired effects, surgeons' rating of the operation condition and patient satisfaction (using 10 cm visual analogue scale) and acceptability of the technique were analyzed. Out of 204 patients, hypotension, bradycardia and nausea occurred in 45.1%, 17.6% and 14.7% respectively. Fifty-six (27.4%) patients experienced discomforts whereas 10.8% had tolerable pain and 4.9% patients required conversion to general anaesthesia. The main causes of discomfort in these patients were inability to move lower limbs in 35.7% and discomfort in the upper limbs in 32.1% of patients. Operating conditions were suboptimal and unacceptable in 3.9% and 4.3% of patients respectively. The mean patient satisfaction VAS score was 8.2 +/- 1.3 and patient acceptability was 90.2%. Significant failure or unacceptability (approximately in 10.0%) along with a high incidence of preventable discomforts demand improvement in preoperative patient education, intra-operative care and liberal uses of sedation to improve the quality to bring the acceptability closer to 100.0%.

Adult↗

PubMed1990

Behavior analysis, cognitive therapy, and covert conditioning.

Branch (The Behavior Therapist 10, 79-84, 1987) and others have expressed interest in extending the behavior analytic framework into the realm of behavior therapy and private events. We point out that several imagery-based behavior therapy procedures such as systematic desensitization, implosive therapy, and covert conditioning were designed to be employed according to learning principles and that covert conditioning is specifically based on principles of operant conditioning. Since the covert conditioning model already combines the advantages of behavior analysis, behavior therapy, and imagery, covert conditioning, rather than cognitive therapy, should be considered by behavior analysts seeking ways to study and modify both private and public events.

Behavior Therapy↗

PubMed1988

Treatment of faecal incontinence in children with spina bifida by biofeedback and behavioural modification.

Faecal incontinence may lead to serious social and physiological disturbances. Over 90% of patients with spina bifida have varying degrees of neurogenic bowel with disturbances of faecal control. This is a serious habilitation problem in these patients. Three encopretic children with myelomeningocele were treated by Biofeedback operant conditioning and behavioural modification to self-initiate bowel movements. Their neurological levels were T-10; T-11; T-12. Each child had a mean of 10 Biofeedback sessions each of 30-45 minutes, combined with daily behavioural modification. Two patients improved and have voluntary bowel movements. Therapy failed in one patient. We conclude that Biofeedback operant conditioning combined with specific behavioural modification may become a simple technique to treat encopretic patients with meningomyelocele.

Behavior Therapy↗

PubMedDate not supplied

Arousal and sensation-seeking components in the general explanation of gambling and gambling addictions.

Following upon the first clear experimental evidence that states of high arousal accompany gambling in real-life situations, an attempt is made to clarify the implications of this new finding for the development of two possible forms of a neo-Pavlovian or classical conditioning addition to the traditional emphasis on operant conditioning in behavioral explanations of gambling. The explanatory scope and power of one (biological hedonist) version of the model is then demonstrated as applied to both normal regular and pathological gambling. The role of arousal and sensation-seeking factors is considered alongside the roles of other likely components in any possible general explanation of both regular and pathological gambling.

Arousal↗

PubMed2006

[Gasification characteristics of waste tires in laboratory-scale fluidized-bed gasifier].

A laboratory-scale fluidized-bed gasifier was designed and used to investigate the characteristics of waste tires gasification. Granulated tires were gasified with different excessive air ratios at a temperature range of 400-700 degrees C. The gasification efficiency, carbon conversion efficiency, heating value, yield and components of syngas were analyzed. Results showed that the optimum operation conditions were achieved when the gasification temperature was 700 degrees C and the excessive air radio (EAR) was 0.4. A gaseous product, mainly containing CH4, CO, H2, C2H6, and longer-chain hydrocarbon with a lower heating value (LHV) of about 4804 kJ/m3, can be generated at the highest gasification efficiency of 47.96% under the optimum operation conditions.

Air Pollutants↗

PubMed1983

Atracurium in clinical anaesthesia.

Atracurium was used on 250 occasions under normal operating conditions in patients between the ages of 18 and 86 yr; 97 patients were aged 65 yr and over, 47 were ASA Grade III, 15 were Grade IV and three were Grade V. Provided that a dose of 0.5-0.6 mgkg-1 was used, intubation was carried out in 1.5 min in 82% of patients. Good operating conditions were obtained in all patients and no complications could be attributed to atracurium even in patients giving a history of allergy or asthma. Residual blockade could be adequately antagonized and recurarization did not occur.

Adult↗

PubMed2003

Combined topical anesthesia and sedation for open-globe injuries in selected patients.

PURPOSE: To evaluate the efficacy and safety of topical anesthesia (TA) and IV sedation in surgery for less severe open-globe injury (OGI). DESIGN: Noncomparative consecutive interventional case series. PARTICIPANTS: Of 67 OGI cases reviewed at the Department of Ophthalmology and Otolaryngology, University of Bari, Bari, Italy, in the period from 1999 to 2000, 10 eyes (14.9%) of 10 consecutive patients (age range, 6-58 years) were repaired using TA and IV sedation. All patients belonged to the American Society of Anesthesiologists risk class I or II. Nine eyes had corneoscleral wounds, four had vitreous loss, two had traumatic cataract, and three had an intraocular foreign body (IOFB); one patient had interruption of a continuous penetrating keratoplasty suture. Preoperatively, best-corrected visual acuity (BCVA) ranged from hand movement to 20/20. INTERVENTION: Corneoscleral suture was performed in nine patients, vitreous excision in four, uveal excision or reposition in four, IOFB removal in three, and cataract extraction in two; corneal button resuture was carried out in one patient. All patients received topical oxybuprocaine hydrochloride 0.4%, and IV propofol, midazolam, and fentanyl for anesthesia. MAIN OUTCOME MEASURES: The change in BCVA was evaluated. Within 24 hours after surgery, each patient was asked to grade subjective pain and discomfort on a 4-point scale. The surgeon was asked to report difficulties attributable to the operating conditions. Complications related to anesthesia and to surgery were assessed. RESULTS: Best-corrected visual acuity stabilized or improved in all patients. All patients had grade 1 pain and discomfort during most of the procedure. All patients had grade 2 (mild) pain and discomfort during external bipolar cautery and conjunctival closure. No patient required additional anesthesia. The operating conditions as reported by the surgeons were graded slightly difficult in all cases but one, which was graded moderately difficult. No patient had surgical or anesthesia-related adverse events or life-threatening complications. CONCLUSIONS: Topical anesthesia and IV sedation are safe and effective and could be a reasonable alternative for less severe OGI. The degree of patient discomfort is only marginal during surgery and postoperatively. However, surgical training and patient preparation are the keys to the safe use of this anesthetic modality.

Adolescent↗

PubMed2002

Anaerobic treatment of polyethylene glycol of different molecular weights.

Biodegradation of high molecular weight polyethylene glycol has been found difficult under aerobic conditions. The use of a chemical treatment prior to the aerobic one was necessary to remove high molecular weight of polyethylene glycol. Anaerobic treatment of polyethylene glycol may present an alternative to integrated chemical and biological treatment for the elimination of this compound. Anaerobic biodegradation of polyethylene glycol from 200 to 10,000 molecular weight was studied. It showed that, unlike aerobic treatment, the size of the molecule up to 10,000 does not affect the process efficiency. The critical retention time and the optimum retention time were estimated and ranged from 10 to 14 and from 16 to 19 days, respectively. Under these operational conditions percentage of removal ranged from 85 to 90%. Thus, anaerobic degradation of polyethylene glycol presents removal percentages and hydraulic retention times compounds similar to those of biodegradable tested at the same operational conditions.

Bacteria, Anaerobic↗

PubMed2001

Generation of xylose solutions from Eucalyptus globulus wood by autohydrolysis-posthydrolysis processes: posthydrolysis kinetics.

Eucalyptus wood samples were treated with water under selected operational conditions (autohydrolysis reaction) to obtain a liquid phase containing hemicellulose-decomposition products (mainly acetylated xylooligosaccharides, xylose and acetic acid). In a further acid-catalysed step (posthydrolysis reaction), xylooligosaccharides were converted into xylose, a carbon source for further fermentation. The kinetic pattern governing the posthydrolysis step was established by reacting xylooligosaccharide-containing liquors at 100.5 degrees C, 115 degrees C, 125 degrees C or 135 degrees C in media containing 0.5, 1.0, 1.5 or 2 wt% of catalyst (sulphuric acid). The time course of the concentrations of xylooligosaccharides, xylose, furfural and acetic acid were determined, and the results were interpreted by means of a kinetic model which allowed a close reproduction of the experimental data. Almost quantitative conversion of xylooligosaccharides into xylose was achieved under a variety of experimental conditions. The first-order, kinetic coefficient for xylooligosaccharide hydrolysis (k1, h(-1)) varied with both temperature (T, K) and molar sulphuric acid concentration (C) according to the equation In k1 = 36.66 + 1.00lnC - 108.0/(8.314T). The hydrolysis of acetyl groups followed a first-order kinetics. The corresponding kinetic coefficient (ka, h(-1) was correlated with the operational conditions by the equation Inka = 26.80+ 1.18 InC - 73.37/(8.314T).

Acetic Acid↗