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At least 1,621 records · Page 90Linked to original sources

PubMed2003

Biodiesel production from waste cooking oil: 1. Process design and technological assessment.

Four different continuous process flowsheets for biodiesel production from virgin vegetable oil or waste cooking oil under alkaline or acidic conditions on a commercial scale were developed. Detailed operating conditions and equipment designs for each process were obtained. A technological assessment of these four processes was carried out to evaluate their technical benefits and limitations. Analysis showed that the alkali-catalyzed process using virgin vegetable oil as the raw material required the fewest and smallest process equipment units but at a higher raw material cost than the other processes. The use of waste cooking oil to produce biodiesel reduced the raw material cost. The acid-catalyzed process using waste cooking oil proved to be technically feasible with less complexity than the alkali-catalyzed process using waste cooking oil, thereby making it a competitive alternative to commercial biodiesel production by the alkali-catalyzed process.

Catalysis↗

PubMed2005

Study and application of a controlled-potential electrochemistry-electrospray emitter for electrospray mass spectrometry.

This paper discusses continued studies and new analytical applications of a recently developed three-electrode controlled-potential electrochemical cell incorporated into an electrospray ion source (Van Berkel, G. J.; Asano, K. G.; Granger, M. C. Anal. Chem. 2004, 76, 1493-1499.). This cell contains a porous flow-through working electrode (i.e., the emitter electrode) with high surface area and auxiliary electrodes with small total surface area that are incorporated into the emitter electrode circuit to control the electrochemical reactions of analytes in the electrospray emitter. The current at the working and auxiliary electrodes, and current at the grounding points upstream and downstream of the emitter in the electrospray circuit, were recorded in this study, along with the respective mass spectra of model compound reserpine, under various operating conditions to better understand the electrochemical and electrospray operation of this emitter cell. In addition to the ability to control analyte oxidation in positive ion mode (or reduction in negative ion mode) in the electrospray emitter, this emitter cell system was shown to provide the ability to efficiently reduce analytes in positive ion mode and oxidize analytes in negative ion mode. This was demonstrated by the reduction of methylene blue in positive ion mode and oxidation of 3,4-dihydroxybenzoic acid in negative ion mode. Also, the ability to control electrochemical reactions via potential control was used to selectively ionize (oxidize) analytes with different standard electrochemical potentials within mixtures to different charge states to overcome overlapping molecular ion isotopic clusters. The analytical benefit of this ability was illustrated using a mixture of nickel and cobalt octaethylporphyrin.

Cobalt↗

PubMed2000

Psychology of the scientist: LXXXII. Coverage of classical conditioning in textbooks in the psychology of learning, 1952-1995.

Objective information was obtained from 89 textbooks in the psychology of learning published from 1952 through 1995 to answer questions about their coverage of classical conditioning. We found (a) that classical conditioning consistently received less coverage than instrumental and operant conditioning, (b) that the distinction of classical and instrumental conditioning has become established as a textbook-construction device, (c) that use of the classical-instrumental distinction by textbook authors has "hardened" after a period of "fluidity" in the 1970s, (d) that the currency of references in the basic classical (as well as instrumental) conditioning chapters diminished from 1952 to 1995. Findings are discussed in regard to the possibility that, as a class, and in comparison to other textbooks, the textbooks of the psychology of learning fall short of fulfilling some of their recognized roles.

Animals↗

PubMed2006

Heat treatment of whole milk by the direct joule effect--experimental and numerical approaches to fouling mechanisms.

The development of alternative technologies such as the direct Joule effect to pasteurize and sterilize food products is of great scientific and industrial interest. Our objective was 1) to gain insight into the ability to ensure ultra-high-temperature treatment of milk and 2) to investigate the links among thermal, hydraulic, and electrical phenomena in relation to fouling in a direct Joule effect heater. The ohmic heater [OH; E perpendicular to v (where E is the electrical field and v is the velocity); P (power) = 15 kW] was composed of 5 flat rectangular cells [e (space between the plate and electrode) = 15 mm, w (wall) = 76 mm, and L (length of the plate in plate heat exchanger or electrode) = 246 mm]--3 active cells to ensure heating and 2 (at the extremities) for electrical insulation and the recovery of leakage currents. In the first step, the thermal performance of the OH was investigated vs. the flow regimen [50 < Re (Reynolds number) < 5,000], supplied power (0 < P < 15 kW), and electrical conductivity of fluids (0.1 < sigma(20 degrees C) < 2 S/m) under clean conditions with model fluids. This protocol enabled a global thermal approach (thermal and electrical balance, modeling of the temperature profile of a fluid) and local analysis of the wall temperature of the electrode. An empirical correlation was established to estimate the temperature gradient, T(w)-T(b) (where T(w) is the wall temperature and T(b) is the product temperature) under clean conditions (without fouling) and was used to define operating conditions for pure-volume and direct-resistance heating. In the second step, the ability of OH to ensure the ultra-high-temperature treatment of whole milk was investigated and compared with a plate heat exchanger. Special care was taken to investigate the heat transfer phenomena occurring over a range of temperatures from 105 to 138 degrees C. This temperature range corresponds to the part of the process made critical by protein and mineral fouling. The objectives were 1) to demonstrate the ability of an OH to ensure heat treatment of milk, 2) to study the thermal and hydraulic performance with an increasing power and temperature difference between the inlet and outlet of the OH, 3) to define and validate a criterion to follow heat dissipation efficiency, and 4) to compare the fouling propensity with the different configurations. A heat dissipation coefficient, Rh(CO), was defined and validated to monitor the fouling propensity through global electrical and thermal parameters. Finally, a numerical simulation was developed to analyze heat profiles (wall, deposit, bulk). Because of an increasing Joule effect in the static deposit, the simulation showed how wall overheating would definitively cause fouling to spiral out of control.

Animals↗

PubMed1997

Silastic medialization for unilateral vocal fold palsy.

From August 1994 to September 1995, 12 silastic medialization procedures were performed for the treatment of vocal fold palsy. The causes included tuberculous fibrosis, carcinoma of the bronchus, post-oesophagectomy for carcinoma of the oesophagus and idiopathy. Early operation was performed in cases due to malignant conditions to relieve symptoms. In those with benign conditions, operation was performed if conservative treatment failed to control the symptoms in six months. The efficacy of silastic medialization for the treatment of dysphonia was evaluated by both subjective and objective voice assessment. The results indicate that the procedure is effective in the relief of dysphonia in unilateral vocal fold palsy. Only one patient in the study required a revision operation due to unsatisfactory voice quality. The procedure has the advantages of being tunable, reversible, and suitable for old and debilitated patients. The long term benefits of the procedure require further study.

Journal Article↗

PubMed1977

[Unexpected findings during surgery for interventricular communication and for banding of the pulmonary artery in the infant and child].

While the authors recognise the difficulty of obtaining a complete picture of the lesion in certain types of ventricular shunt with pulmonary hypertension, they emphasise the importance of a precise diagnosis, which may modify the medical treatment and the decision to operate. Conditions may nevertheless be found by surprise at operation, and lead to a modification of the planned action.

Child, Preschool↗

PubMed1998

OH-radical formation by ultrasound in aqueous solution--Part II: Terephthalate and Fricke dosimetry and the influence of various conditions on the sonolytic yield.

Terephthalate and Fricke dosimetry have been carried out to determine the sonolytic energy yields of the OH free radical and of its recombination product H2O2 in aqueous solutions under various operating conditions (nature of operating gas, power, frequency, temperature). For example, in the sonolysis of Ar-saturated terephthalate solutions at room temperature, a frequency of 321 kHz, and a power of 170 W kg-1, the total yield [G(.OH) + 2 G(H2O2)], equals 16 x 10(-10) mol J-1. This represents the total of .OH that reach the liquid phase from gas phase of the cavitating bubble. The higher the solute concentration, the lower the H2O2 production as more of the OH free radicals are scavenged, in competition with their recombination. Fricke dosimetry, in the absence and presence of Cu2+ ions, shows that the yield of H atom reaching the liquid phase is much lower, with G(H.) of the order of 3 x 10(-10) mol J-1. These sonolytic yields are smaller in solutions that are at the point of gas saturation, and increase to an optimum as the initial sonication-induced degassing and effervescence subsides. The probing of the sonic field has shown that the rate of sonolytic free-radical formation may vary across the sonicated volume depending on frequency and power input.

Journal Article↗

PubMed2003

Production of polyhydroxyalkanoates by a mixed culture in a sequencing batch reactor: the use of propionate as carbon source.

In this work, sludge adapted to anaerobic/aerobic conditions, AN/AE, showing a high capacity of P accumulation, was submitted to aerobic dynamic substrate feeding (ADF). The fermenter was operated as a Sequencing Batch Reactor, with propionate as carbon substrate. Propionate is an important waste product from several industrial processes that can be valued, using it as a precursor for hydroxyvalerate in PHA production. Under the operational conditions used, apart from 3-hydroxyvalerate as its major component, 3-hydroxy-2-methylvalerate, 2-hydroxyisovalerate and 4-oxovalerate were also produced. A second reactor operated under the same conditions was adapted for the use of acetate as carbon substrate. The global metabolism of the organisms involved on PHA production, utilizing acetate or propionate, was studied using in vivo 13C Nuclear Magnetic Resonance (NMR).

Alkanes↗

PubMed2005

[Peri-operative management of the primary hyperparathyroidism].

Surgery for primary hyperparathyroidism has become one of the least invasive and safe procedures with the recent advances in the diagnosis and surgical technique. However, it is still difficult to prospect detailed post-operative conditions of the patient from the data of pre-operative examination. Because many factors related each other to make the preoperative conditions complicated. Thus, integrated interpretation of the patient is necessary before surgery, including general condition, coincidental disease, renal function, bone mineral density and its turnover, size and location of the lesion. Prevention and proper management of postoperative complications, such as hemorrhage, hypocalcemia, hoarseness and bone disease, is important for successful treatment of the disease.

Humans↗

PubMed1982

Changes in hippocampal rhythmic slow activity during instrumental cardiovascular conditioning in the monkey (Macaca mulatta).

Analyses of 4-8 Hz electrical activity (RSA) of the mid-ventral hippocampus, motor activity (M), and blood pressure were carried out during experiments in which three monkeys were operantly conditioned to slow heart rate (HR), to speed HR or during control, no feedback (FB) periods. The results showed that RSA activity was greater during contingent HR (FB) slowing than during HR slowing noncontingent (FB) for all three animals. Motor activity tended to show small changes across conditions; however, it was higher during HR speeding and lower during HR slowing in two animals. There was no differential effect of FB on motor activity for any animal. Blood pressure changes were small and variable throughout conditioning, RSA changes tended to be highly consistent both early and late in conditioning. Results are discussed in terms of attentional and somatic factors that may be operative during instrumental cardiovascular conditioning.

Animals↗

PubMed2005

Treatment of septage in constructed wetlands in tropical climate: lessons learnt from seven years of operation.

In tropical regions, where most of the developing countries are located, septic tanks and other onsite sanitation systems are the predominant form of storage and pre-treatment of excreta and wastewater, generating septage and other types of sludges. The septage is disposed of untreated, mainly due to lack of affordable treatment options. This study presents lessons that have been learned from the operation of pilotscale constructed wetlands (CWs) for septage treatment since 1997. The experiments have been conducted by using three CW units planted with narrow-leave cattails (Typha augustifolia) and operating in a vertical-flow mode. Based on the experimental results, it can be suggested that the optimum solids loading rate be 250 kg TS/m2 yr and 6-day percolate impoundment. At these operational conditions, the removal efficiencies of CW units treating septage at the range of 80-96% for COD, TS and TKN were achieved. The biosolid accumulated on the CW units to a depth of 80 cm has never been removed during 7 years of operation, but bed permeability remained unimpaired. The biosolid contains viable helminth eggs below critical limit of sludge quality standards for agricultural use. Subject to local conditions, the suggested operational criteria should be reassessed at the full-scale implementation.

Agriculture↗

PubMed2004

The S6KII (rsk) gene of Drosophila melanogaster differentially affects an operant and a classical learning task.

In an attempt to dissect classical and operant conditioning in Drosophila melanogaster, we have isolated the gene for ribosomal S6 kinase II (S6KII). This enzyme is part of a family of serine-threonine kinases that in mammals have been implicated in the MAPK (mitogen-activated protein kinase) signaling cascade controlling (among other processes) synaptic plasticity (long-term potentiation/long-term depression) and memory formation. The human homolog rsk2 has been linked to mental retardation (Coffin-Lowry syndrome). Mutant analysis in Drosophila shows that S6KII serves different functions in operant place learning and classical (pavlovian) olfactory conditioning. Whereas in the null mutant only pavlovian olfactory learning is affected, a P-element insertion mutant reducing the amount of S6KII only affects operant place learning. A mutant lacking part of the N-terminal kinase domain and performing poorly in both learning tasks is dominant in the operant paradigm and recessive in the pavlovian paradigm. The behavioral defects in the pavlovian task can be rescued by the genomic S6KII transgene. Overexpression of S6KII in wild type has a dominant-negative effect on the operant task that is rescued by the null mutant, whereas in the pavlovian task overexpression may even enhance learning performance.

Animals↗

PubMed2000

Pre-operative endometrial thinning agents before hysteroscopic surgery for heavy menstrual bleeding.

BACKGROUND: Menorrhagia is one of the most common reasons for pre-menopausal women to be referred to a gynaecologist. Although medical therapy is generally the first approach, many will eventually require or request a hysterectomy. Hysterectomy is associated with a significant in-patient hospital stay and a period of convalescence that makes it an unattractive and unnecessarily invasive option for many women. Hysteroscopic endometrial ablation or resection offers a day-case surgical alternative to hysterectomy for these women. It is also a cheaper procedure than hysterectomy. Complete endometrial removal or destruction is one of the most important determinants of treatment success. Therefore surgery will be most effective if undertaken when endometrial thickness is less than 4mm, in the immediate post-menstrual phase, however there are often difficulties in reliably arranging surgery for this time. The other option is the use of hormonal agents which induce endometrial thinning or atrophy prior to surgery. The most commonly evaluated agents have been goserelin (a GnRH analogue) and danazol. Progestogens and other GnRH analogues have also been studied although less data are available. It has been suggested that the use of these agents, particularly GnRH analogues, will reduce operating time, improve the intra-uterine operating environment, and reduce distension medium absorption (this is the fluid used to distend the uterine cavity during surgery). OBJECTIVES: To investigate the effectiveness of gonadotrophin-releasing hormone (GnRH) analogues, danazol, and progestogens, when used for endometrial thinning prior to hysteroscopic surgery for menorrhagia, in improving the intra-uterine operating environment and treatment outcome after surgery. SEARCH STRATEGY: The Menstrual Disorders and Subfertility Group search strategy (see Review Group details) was used to identify randomised trials that had compared the use of these drugs with either each other, or placebo, or no pre-operative treatment. SELECTION CRITERIA: Trials were included if they compared the effects of these agents with each other, or with placebo or no treatment on relevant intra-operative and post-operative treatment outcomes. Only randomised studies were included in this review. DATA COLLECTION AND ANALYSIS: Eight studies met the inclusion criteria for this review. Four studies compared goserelin (a GnRH analogue) with no treatment or placebo. Three studies compared goserelin with danazol. One study compared progestogens, danazol and triptorelin (a GnRH analogue) with no treatment. Data was extracted independently by two reviewers. A third reviewer checked data extraction for accuracy and wrote to authors where relevant data was missing or unclear. Intra-operative parameters included endometrial thickness, duration of surgery, ease of surgery, distension medium absorption and complication rate. Post-operative outcomes compared were the proportion of women with amenorrhoea, post-operative menstrual loss and dysmenorrhoea, and the need for further surgery. Data on side-effects were also recorded. MAIN RESULTS: When compared with no treatment GnRH analogues are associated with a shorter duration of surgery, greater ease of surgery and a higher rate of post-operative amenorrhoea. Post-operative dysmenorrhoea also appears to be reduced. The use of GnRH analogues has no effect on intra-operative complication rates and patient satisfaction with this surgery is high irrespective of the use of any pre-operative endometrial thinning agent. GnRH analogues produce more consistent endometrial atrophy than danazol. For other intra-operative and post-operative outcomes any differences are minimal. Both GnRH analogues and danazol produce side-effects in a significant proportion of women, though few studies have reported these in detail. Little randomised data is available to assess the effectiveness of progestogens as endometrial thinning agents and the effect of any thinning agent

Danazol↗

PubMed1975

Dosimetry of portable image intensifiers in pacemaker insertions.

With the increased utilization of portable image intensifiers for pacemaker insertions, an investigation of the radiation hazards to operative personnel was undertaken. The personnel were tested first utilizing a Rando phantom and later during actual pacemaker insertions. Studies of medical personnel show the critical organs to be the thyroid (approximately 15mR per procedure) and the lens of the eye (approximately 13mR per procedure). While the MPD/week was not exceeded, the radiation dosage was substantial and could increase under operating conditions other than those measured. Recommendations to insure safer operation of this equipment are presented.

Fluoroscopy↗

PubMedDate not supplied

A note on conditional reflex studies of schizophrenia in France.

In France, beginning with 1946, the method of Ivanov-Smolenski was used to study schizophrenia, but after 1957, sensory conditioning procedures have been employed (EEG sound-light, evoked potentials in children, SAE conditioning in adults) and more recently eye blink and operant conditioning.

Conditioning, Classical↗

PubMed1989

Operator limitations in farm tractor overturn recognition and response.

Accounting for nearly half of all work-related farm tractor injuries annually, tractor side and rear overturn continue to be an ongoing problem. The causes of both side and rear overturns may be grouped into design-related and human factors-related categories. This review addresses the latter, highlighting those information processing bottlenecks, some of which may be aided through training or stability indicator devices. It is argued that tractor instability must first be perceived before a corrective response may be taken. Evidence was drawn from orientation perception, tractor rollover response time, and driving studies to describe an overall model of the tractor operator attempting to stay within stable operating conditions. With this more precise model of the tractor operator, a foundation is provided for further research on the operator-tractor interface.

Journal Article↗

PubMed1992

Short-cut method for predicting the productivity of affinity chromatography.

A method was developed for predicting the productivity P (amount of the target protein recovered per unit volume per unit time) of affinity chromatography (AFC) and similar chromatographic operations. The constant-pattern approach was employed for describing the breakthrough curve. It was found that P increases with increasing u at low u regions and there is a maximum in the P-u curve. The u value that gives the maximum P (uM) was derived as a function of the number of transfer units, n. The experimental breakthrough curves for several different packing media systems such as 40- and 10-microns porous particles, 2.5-microns non-porous particles and surface-derivatized membrane media were measured, from which the n values were determined. The uM values were then calculated using the n values. It is suggested that the present method is useful for the rapid survey of the operating conditions in scaling-up AFC and similar chromatographic operations.

Chromatography, Affinity↗

PubMed1996

Development of electrophoretic conditions for the characterization of protein glycoforms by capillary electrophoresis-electrospray mass spectrometry.

A capillary electrophoresis (CE) method using acidic buffers and capillaries coated with Polybrene, a cationic polymer has been developed for the separation of glycoproteins and glycopeptides. Electrophoretic conditions have been optimized to provide resolution of individual glycoforms observed for different glycoprotein preparations. These conditions were found to be entirely compatible with the operation of electrospray mass spectrometry (ESMS), which facilitated the assignments of possible carbohydrate compositions of glycopeptides arising from digests of glycoproteins. By using operating conditions enhanced the formation of oxonium fragment ions prior to mass spectral analysis, selective identification of glycopeptides was achieved for complex samples such as those from proteolytic digests or chemical cleavages. Examples of applications are presented for ribonuclease B, ovalbumin, horseradish peroxidase, and a lectin from Erithrina corallodendron using both CE-ESMS and CE with ultraviolet detection (CE-UV).

Carbohydrate Conformation↗