Liquid Reflux Research Articles

Patterns of gas and liquid reflux in patients with gastroesohageal reflux disease

Patterns of gas and liquid reflux in patients with gastroesohageal reflux disease

The Esophagus for the Nonesophagologist

The esophagus is a muscular tube (striated muscle at the top end, smooth muscle in the middle and lower portion) connecting the pharynx and the stomach. It is closed at both the top and bottom ends by specialized muscular sphincters. Deglutition begins as a programmed act, mediated by nerve fibers from the brain stem, and spreads aborally with a wave of inhibition preceding a moving-ring contraction that obliterates the lumen of the esophagus. Fluids fall by gravity in the upright position or are pushed down by the moving ring contraction when the subject is horizontal. There are several factors that prevent constant regurgitation of gastric contents back into the esophagus. Reflux of both gas and liquid does occur as a normal event. The esophagus usually performs its job description of transferring material from the pharynx to the stomach and venting the stomach when necessary with a minimum of fuss.

Wegener's granulomatosis of the skull base

(Editorial Comment: The authors present a unique presentation of Wegener’s granulomatosis integrated with an outstanding literature review.) Wegener’s granulomatosis (WG) is a clinicopathologic diagnosis that requires a history of upper and lower respiratory symptoms with tissue biopsy confirmation. Histopathologitally, it is characterized by the triad of acute necrotizing granulomas of the upper and lower respiratory tracts, focal necrotizing vasculitis, and focal necrotizing glomerulonephritis. This disease often begins as a localized process. Left untreated, it usually progresses to systemic disease and is usually fatal secondary to renal and pulmonary failure, with a mean survival of 5 months and 90% mortality rate at 2 years.’ In up to 90% of patients, the first symptoms arise in the head and neck region.z Manifestations predominantly involve the ears, nasal and paranasal mucosa, larynx, and oral cavity. Early diagnosis allowing prompt treatment may prevent progression to serious disease. We present a patient whose lesion was localized to the nasopharynx and base of skull and whose first symptoms arose secondary to multiple cranial neuropathies. CASE REPORT A 29-year-old black woman presented to the Emergency Room complaining of left hemifacial pain, dysphagia, hoarseness, occasional hemoptysis, nausea, vomiting, weight loss, and general malaise. She denied nasal discharge or nasal congestion. The patient’s voice was hypernasal, and she admitted to nasal reflux of liquids during swallowing. She also admitted to left subjective hearing loss

Process integration involving lipase-catalyzed ester synthesis reactions

The technical feasibility of integrating bioconversion (using a lipase from Mucor miehei immobilized by ion exchange onto a macroporous resin) and product recovery (via mass transfer towards liquid/vapor equilibrium) was experimentally verified for the production of ethyl acetate from acetic acid and ethanol at 30 and 40 °C. The configuration selected consisted of a packed bed thermostatted reactor inserted between the condenser and the liquid reflux to a distillation column. The concentrations of the aforementioned components and water were measured periodically for a 9 to 10-h period. The extents of conversion of acetic acid ranged from 1 to 32% at 30 °C, and from 13 to 25% at 40 °C, and they were maximum at initial molar fractions of acid of ca. 0.3 and 0.4, respectively. The ratio of the reaction product to the equilibrium reaction product increased from 2 to 32 at 30 °C, and from 5 to 27 at 40 °C when the initial molar fraction of acid in the feed increased from 0.2 to 0.7.

Temporary obturation of anterior residual clefts: Preliminary clinical report

In bilateral cleft lip and palate children, reflux of liquids and food into the nasal cavity, hypernasality and other speech deficiencies, displacement and risk of traumatic injuries to the premaxilla may be consequences of delayed surgical closure of the anterior palate. To address these problems, temporary obturation was undertaken with a newly designed orthopedic plate. The plate was well accepted by the ten consecutively treated patients and obturation was achieved in a clinical sense. The position of the premaxilla was corrected and maintained. Speech and intraoral air pressure were assessed. Both abilities improved with training and time after insertion of the plate.

Inhibition of aminoimidazoquinoxaline-type and aminoimidazol-4-one-type mutagen formation in liquid reflux models by L-tryptophan and other selected indoles.

The essential amino acid l‐tryptophan (l‐Trp) was found to be an effective inhibitor of the development of mutagenicity (Ames test) in liquid‐reflux models known to produce identified IQ‐type mutagens, such as 2‐amino‐3,8‐dimethylimidazo[4,5‐f]quinoxaline (MeIQx) and 2‐amino‐3,7,8‐trimethylimidazo[4,5‐f]qninoxaline (7,8‐DiMeIQx), and in reflux models recently developed in our laboratory that have been found to produce novel IQ‐“like” mutagens (aminoimidazol‐4‐ones), which we have identified as 2‐amino‐1‐methyl‐5‐propylideneimidazol‐4‐one (TCP‐1), and 2‐amino‐5‐ethylidene‐1‐methylimidazol‐4‐one (TCP‐2 or ACP). Selected indoles other than l‐Trp were also found to be effective inhibitors of mutagen formation in these same reflux models. A mechanism of inhibition of mutagen formation based on the preferential reaction of mutagen precursor aldehydes with the indole‐ring nitrogen of these inhibitors, rather than with creatinine, is indicated, and a new “concerted condensation model” for the formation of IQ‐type mutagens proposed.

Relationship of Transient Lower Esophageal Sphincter Relaxation tai Post randial Gastroesophageal Reflex and Belching in Dogs

Methods have been developed for the recording of patterns of motor function associated with spontaneous gastroesophageal reflux and belching in trained, unsedated dogs. Pharyngeal, esophageal body, lower esophageal sphincter (LES), and gastric pressures were monitored in 3 dogs with a manometric assembly inserted through a cervical esophagostomy. Spontaneous changes in esophageal pH were recorded simultaneously with a glass electrode. Each dog was studied three times for 3 h starting directly after completion of a full-sized meal. Acid reflux was recorded on 40 occasions; on 35 of these occasions it was possible to analyze, in detail, motor events at the time of reflux. This analysis showed that the LES was completely relaxed at the time of reflux and that the relaxation occurred within the 15 s before the onset of esophageal acidification. In 77% of the reflux episodes LES relaxation occurred independently of swallowing or any other motor event. The remainder of the LES relaxations associated with reflux were secondary to a swallowing salvo or a single swallow that did not trigger an esophageal body peristaltic wave. Straining was associated with reflux during many episodes of LES relaxation, but did not induce reflux if there was measurable LES pressure. Belching was also related to complete LES relaxations with a pattern identical to that associated with acid reflux. In the dog, liquid and gas reflux occurred during transient LES relaxations that were very similar to those that allow reflux to occur in humans. The dog is a suitable model for investigation of the nature and control of reflux associated with transient LES relaxation.

Gastro-oesophageal reflux and gastric emptying of liquids in paediatric patients

The relationship of delayed gastric emptying to gastro-oesophageal reflux in 100 paediatric patients is described. A quantitative method using a radionuclide marker, for determining proportions of gastric retention of liquids at different times after ingestion was employed in a study of gastro-intestinal tract transit. A comparison of this examination with other methods is discussed.

The simulation of steady state behaviour of the dephlegmation of multi-component mixed vapours

The partial condensation or dephlegmation process is generally used for the production of liquid reflux and vaporous disdilate with an additional fractionation in wetted wall column heat exchangers. All known calculations of the performance of vapour condensers are based on a film model, originally derived for binary vapour systems by Ackermann and by Colburn and Drew and generalized for multi-component vapour systems by Standart and Krishna using a general matrix models for the multi-component mass transfer with the more accurate model of Standart and Krishna is given for the partial condensation of a ternary vapour system.

Simulation of the unsteady state behaviour of the dephlegmation of binary vapour mixtures

The partial condensation or dephlegmation process is generally used for the production of liquid reflux and vaporous distillate with an additional fractionation in a wetted wall column with a countercurrent flow of vapour and liquid resp. coolant. All know calculations of the performance of binary vapour condensers are based on a generalized model (using the Ackermann-Colburn-Drew equations), which only describes the steady state behaviour. In this paper the model is extended to include the unsteady state behaviour and is used for two characteristic examples.

Desalination in pilot scale column crystallizers

Results obtained from the continuous operation of a two inch-diameter column crystallizer and scale-up considerations involved in the design of a four inch column are presented. Implications of a mathematical model for continuous column crystallizers are discussed, including countercurrent flow of reflux liquid phase and crystal phase, leading to a reduction in salt concentration in liquid adhering to the crystal. The factors discussed include speed of crystal transport and superimposition of oscillatory motion, column length and attitude, feed location in column and the effect of product to feed ratio. Variations in crystal rate are considered and diffusion and mass transfer coefficients calculated. A value for the optimum crystal production rate is derived.

Distillation performance of wetted-wall column with improved wetting characteristics in the range of low reflux rate under reduced pressure.

To achieve an effective distillation in a wetted-wall column in the range of low liquid reflux flow rate, a swathed glass tube, a ground glass tube and a stainless steel mesh tube were used as the wall surface with improved wetting characteristics. Their efficiency results have shown a serious dependency of wettability and an effect of heat transfer from surroundings to system and between phases. The swathed glass tube has the widest range for effective operation of the three in a surface tension positive system, and also shows an extremely good performance in a negative system in comparison with smooth glass tube. And the other two, which have the same efficiency as that for the swathed tube in a positive system above the minimum wetting rate, are more wettable and effective than the smooth glass in a negative system. Analytical treatments have been also made by use of a model to consider the effect of vaporization due to heat transfer. The result obtained points out a significant effect of evaporation in the low vapor flow range and accounts for the deviation of the experimental data from theoretical solution in such a range to some extent.

Pyloric reflux: a modification of the two-component hypothesis of gastric secretion.

1. Gastric juice was obtained during continuous maximal stimulation with histamine diphosphate, 0.13 μmol h−1 kg−1 (0.04 mg h−1 kg−1) intravenously, in thirty-four control subjects, twenty-eight patients with duodenal ulcer, and eighteen with gastric ulcer. After correction for pyloric losses, the average rate of outputs of water, and of H+, Na+, K+ and Cl− were determined. 2. The results were analysed in terms of the two-component theory of gastric secretion. The acid components in control subjects and duodenal ulcer patients were similar in composition, but that in gastric ulcer patients was by comparison hypotonic and less acid and contained more sodium ions. 3. Calculation of the volume and composition of the alkaline component gave reasonable results in the control and duodenal ulcer groups, but impossible results in the gastric ulcer group. The gastric juice of gastric ulcer patients could not be described in terms of classical two-component theory. 4. In all three groups, volume correlated quite well with Cl− output alone, less well with H+ output, poorly with K+ output, and not at all with Na+ output. However, when volume was expressed as a function of the outputs of Cl− and one other ion, K+ performed poorly, H+ well, and Na+ best of all. 5. Some features suggest that reflux of alkaline liquid from the duodenum is a better explanation of these results than back-diffusion of H+ in exchange for Na+ between the lumen and wall of the stomach. 6. If the refluxing liquid is assumed to be isotonic, its composition can be calculated. Hence, the volume of reflux in a sample of gastric juice can be deduced. Reflux appeared to be more important in the gastric ulcer patients than in the other two groups.

Selection of the number of condensation plates in the vacuum rectification column of an atmospheric-vacuum tubular unit

1. A method has been recommended for calculating the condensation trays of the vacuum rectification column of atmospheric vacuum tubular units, which permits a well justified choice of the number of trays and of the mass flow rate of the reflux liquid for the removal of heat. 2. It has been shown that, with an increase in the number of condensation trays from one or two to three or four, there is a sharp decrease in the mass flow rate of reflux liquid for the removal of heat. A further increase in the number of trays changes this index only slightly. 3. A considerable effect of the mean efficiency of the trays on the operating indices of the condensation part of the column has been demonstrated. The use of trays with an efficiency lower than 0.5 brings about an increase in the number of trays, of the mass flow rate of the reflux liquid, and of the temperature at the top of the column.

Influence of Liquid Hold-up in Still to the Rate of Approach to Equilibrium of a Packed Distillation Column

The rate of approach to equilibrium of a packed distillation column with finite hold-up of liquid in the still was analysed in a case of top liquid feed, top vapor discharge and no reflux liquid. From the strict results, the following simplified approximate solution was derived.(23) where This equation means that the time required for 99% approach to equilibrium is proportionate to the amount of liquid hold-up in the still and is inversely proportionate to the rate of liquid flow. Prerequisite conditions for the derivation of approximate solution were summerized in Eq.(26) and Eq.(27).An experiment of the enrichment of heavy water in the flow sheet shown in Fig. 5 was conducted under atmospheric pressure. The calculated values by the use of approximate equation showed a fairly good agreement with the observed values, as shown in Fig. 6 and Fig. 7.

Concentration and plate efficiency in distillation columns

The influence of liquid concentration and reflux ratio on plate efficiency has been studied for the system n-heptane-methylcyclohexane using a sieve plate column with 8 trays. A definite decrease in plate efficiency is found if the concentration of one component is of the order of 0·1 mole per cent. but the decrease in plate efficiency is less than reported for the mixture ethanol-water. The system n-heptane-methylcyclohexane appears to follow Raoult's law better than would follow from the existing equilibrium data.

Retification in a Wetted-wall Tower

A series of rectificat on tests on the methanol-water, ethanol-water, benzene-toluene, and carbontetrachloride-toluene mixtures were performed in a wetted-wall tower.The wetted-wall tower used was a glass tube, 22mm in inside diameter and 1010mm in length. Vapor from the electrically heated kettle rose up through the tower, and mass transfer took place between vapor and reflux, which flowed in layer form down the inner wall of the tower. Part of the vapor from the tower was condensed in the partial condenser directly coupled to the tower, and admitted to the tower as reflux at its boiling point. The remainder of the vapor was condensed in the total condenser and fed back to the kettle. The equipment was operated as a closed system. The tower and the lower part of the partial condenser were enclosed in heater jackets to minimize heat losses.Vapor flow was varied considerably by adjustment of the power input to the kettle, and reflux rates were controlled by cooling water supply to the partial condenser. Rates of vapor flow were determined by direct measurement of reflux liquid from the tower and distillate for a 30-second period. The compositions of liquid and vapor were varied over wide range. Analyses were made on the distillate and the reflux at the top and bottom. Vapor compositions were obtained by calculation.The experimental results in turbulent flow showed that the overall coefficient of mass transfer Ky [kg-mol/m2. hr. Δy], based on the vapor compesition differences as driving forces, was affected mainly by the velocity of vapor, and was independent of the rate and compesition of reflux or the slope of equilibrium curve. For a given system, Ky was proportional to the 0.8 power of the mass velocity G or Reynolds number Re of vapor; and at the same value of G, Ky was proportional approximately to the 3/4 power of the molal vapor diffusivity Dm of the mixture.The data could be correlated by the following equation:where d=inside diameter of tower;X=effective total vapor film thickness;ky=vapor film coefficient of mass transfer;Dm=in the brackets in kg-mol/m. hr.For vapor mixtures, whose viscosity was in the vicinity of 0.01 centipoiscs, the following approximate equation could also be used:where, ky in kg-mol/m2. hr. Δy, G in kg/m2. hr, Dm in kg-mol/m. hr, and d in m.The experimental data were w thin ±15% of these equations.

NEUROLOGICAL SOCIETY OF PARIS

NEUROLOGICAL SOCIETY OF PARIS