Search

The effect of doping distilled water with MgSO4 on the boiling flow regime and heat transfer on a vertical surface at low pressures was experimentally determined. The experiments were performed in a sealed 20 mm x 20 mm square cross section, 300 mm long vertical pipe. Two opposing walls were made of copper and the other two walls were made of polycarbonate for flow visualization. The tube was filled to 100 mm and heat was applied at the lower end of one copper wall and cooled at the upper end. The boiling dynamics on the heated copper vertical wall and the resulting two phase flow was visualized using a high speed camera for pure distilled water and 0.1 M, 0.2 M and 0.4 M concentrations of MgSO4. The presence of MgSO4 significantly changed the boiling dynamics, with a suppression of bubble coalescence and a promotion of nucleate boiling. The two phase flow exiting the heated section changed from slug to bubbly with the addition of the MgSO4. There was a significant increase in the heat transfer coefficient with the addition of the MgSO4. [ABSTRACT FROM AUTHOR]

The liquid turbulence kinetic energy transfer between the liquid and gas phases was investigated for upward air-water bubbly flow in a 200 mm diameter pipe. The liquid and gas axial momentum equations were analyzed to estimate the interfacial drag from experimental measurements, and hence the liquid turbulence production due to the relative velocity of the bubbles. The liquid turbulence production due to the bubbles was significantly higher than that due to the liquid shear. The liquid turbulence kinetic energy budget indicates that the turbulence production due to the bubbles is approximately balanced by the viscous dissipation, estimated assuming an isotropic turbulence structure, with negligible dissipation due to the bubbles. The liquid turbulence kinetic energy spectra showed an addition of energy at length scales in the range corresponding to the bubble diameter. A model for the turbulence energy production spectra due to the bubbles is proposed and used to investigate the spectral turbulence energy budget. The model indicates that when there is a liquid turbulence augmentation, most of the production occurs in the low wave number range with only a small overlap with the viscous dissipation region. In the case of a turbulence suppression, most of the bubble production occurs in the same wave number range as the viscous dissipation. [ABSTRACT FROM AUTHOR]

A two-phase capillary evaporator has been enhanced using Electrohydrodynamic (EHD) forces. The evaporator was experimentally investigated under dc applied electric field operating modes as well as without an applied electric field. The results without the applied EHD forces show that the induced flow increases with increasing applied heat loads until a dry out condition is reached. The applied dc voltage electric field provides flow enhancements as high as 200%. A slight polarity effect was observed. [ABSTRACT FROM AUTHOR]

The void fractions, flow regimes, and pressure drop of air-oil two-phase flow in a half-inch diameter pipe over a wide range of test conditions have been investigated. The flow regimes were identified with the aid of a 1000 frames per second high-speed camera. A capacitance sensor for instantaneous void fraction measurements was developed. The mean and probability density function of the instantaneous void fraction signal can be used to effectively identify the different flow regimes. The current flow regime data show significant differences in the transitional boundaries of the existing flow regime maps. Property correction factors for the flow regime maps are recommended. The pressure drop measurements were compared to the predictions from four existing two-phase flow pressure drop models. Though some of the models performed better for certain flow regimes, none of the models were found to give accurate results over the entire range of flow regimes. [ABSTRACT FROM AUTHOR]

Diffusive thermohaline staircases have been observed over wide regions of the Northwestern Weddell Sea in the March 1986 AMERIEZ experiments. The spatial distribution and temporal evolution of these staircases suggests that these layers may migrate upwards and also may bifurcate into multiple layers. These observations provided the motivation for a laboratory study of the evolution of thermohaline staircases. In the present study, a thermohaline staircase was generated by heating a stable salinity gradient from below. The thicknesses of the convecting layers, heat and salt transports across the interfaces, and migration of the interfaces due to interracial turbulent mixing were measured. During the experiments, the interfaces and convecting layers evolve with time, ultimately assuming steady positions and thicknesses h. The experimental measurements of h, away from the bottom boundary, were found to be in good agreement with a theoretical prediction based on the assumption that a balance between the kinetic and potential energies of the turbulent eddies within the convecting layers sets the thicknesses of the convecting layers. Further, the laboratory data showed an excellent agreement with the oceanic data gathered by the previous investigators. Because of buoyancy transport across the interfaces, the stratification in the system weakens and the buoyancy jump Ab across the interfaces reduces. When the interfacial Richardson number Ri = Δbδ/w[sup *2], where δ is the thickness of the interface and w* is the convection velocity in the layers, drops below a critical value Ri[sub c],which is about 1.5, the interfaces showed rapid migration to new quasiequilibrium levels, at which they remain stationary until Ri drops below Ri[sub c] again. Flow visualization studies show that these rapid migrations are caused by engulfment of the interfacial layer fluid by the eddies of the lower, strongly convecting, layers. The experiments also show that, under... [ABSTRACT FROM AUTHOR]

The mass transfer in back-to-back elbows arranged in an out of plane configuration has been measured under annular two phase air-water flow conditions. The measurements were performed using a wall dissolving technique with the elbow sections cast from gypsum. Experiments were performed to study the effect of increasing the water and air superficial velocities, and the effect of separation distance between the elbows. The highest mass transfer for all cases occurs on the outer wall of the first elbow, and the magnitude was not affected by the separation distance between the elbows. The maximum mass transfer in the second elbow was approximately 60 percent of the maximum value in the first elbow. The mass transfer increased with an increase in either the water or air superficial velocity, with the air velocity having a greater effect. The roughness development in the upstream pipe was modest, but was significant in the regions of high mass transfer on the first and second elbow. [ABSTRACT FROM AUTHOR]

The hepatitis B antigen/antibody levels and natural killer cell activity status of chronic hepatitis B patients identified by the Hawaii State Department of Health were evaluated to select chronically infected hepatitis B patients for interferon therapy and to determine possible immunodeficiencies. The presence of hepatitis Be antigen denotes active replication of the virus. Ninety-five patients were studied: 17/95 (18%) had chronic active hepatitis B, 71/95 (75%) were hepatitis B carriers and 7/95 (7%) had seroconverted. NK activity to the erythroleukemia K562 cell and virus-infected HSV-1 cell of the chronic active and carrier population (P < .05) were lower than that of the control population and those who had spontaneously seroconverted. Of this population 18% were identified with active viral infection and would be candidates for interferon therapy.

This study examined the changes from the initial peak flows and oxygen saturations (OSAT) of wheezing children at presentation to the emergency department through their treatment in the emergency department. Data was collected prospectively on 785 patients 5 to 20 years of age during an 11-month period from November 1, 1990, to September 30, 1991. Both the initial OSAT and peak flows were correlated with the number of bronchodilator treatments required in the emergency department and with the need for hospitalization. Both the initial OSAT and the peak flows had a limited ability to predict the need for hospitalization. Oxygen saturation appears to be a valid measure of wheezing severity and is more easily obtained in children of all ages. Following bronchodilator treatment, peak flow results in a larger quantitative improvement than OSAT; however, this difference does not appear to have any significant advantage. Aerosolized albuterol and subcutaneous epinephrine resulted in a similar degree of improvement as measured by peak flow and by oxygen saturation, with clinically similar changes in heart rate.

Peripheral blood monocytes (PBM) from normal individuals, infectious mononucleosis (IM) and leprosy patients were stimulated with liposome. The mean and standard error of superoxide anion (O2-) generated in nm/1.5 X 10(5) PBM/well for 5 normal subjects and 3 IM patients was 2.9 +/- 0.5 and 3.1 +/- 0.2, respectively. Monocytes stimulated with 100 ng C-reactive protein (CRP) incorporated into liposome gave values of 3.3 +/- 0.3 and 2.7 +/- 0.1 nm O-2/1.5 X 10(5) PBM/well for normals and IM, respectively. No significant differences in O2- production between liposome and liposome with incorporated CRP were shown. PBM from lepromatous patients demonstrated a significant (p less than 0.01) increase in O2- production with liposome alone compared with tuberculoid patients (3.5 +/- 0.4 vs 1.8 +/- 0.3). The most dramatic suppression of O2- shown when purified CRP was added to the mixtures in all groups examined [0.4 +/- 0.1 (500 ng), 0.3 +/- 0.0 (500 ng), 1.5 +/- 0.1 (100 ng), and 1.3 +/- 0.6 (100 ng) nm O2-/1.5 X 10(5) PBM/well for normals, IM, lepromatous, and tuberculoid, respectively]. Results of O2- formation with incorporation of CRP into liposome as compared with liposome alone had no significant effect on PBM of lepromatous or tuberculoid patients. It is suggested that CRP may play a significant role in regulation of oxygen free radicals formed during acute and chronic inflammatory episides.

Natural killer cell cytotoxicity of mononuclear cells and the corresponding plasma prostaglandins were examined in cord blood. Low NK cell cytotoxicity was demonstrated against three target cells: NK(K562), NK(HSV-1) and NK(Fs). Prostaglandins of the B, E and F series were examined and found to be higher than adult values. A significant correlation (p less than 0.05) between NK cell cytotoxicity and the prostaglandin F series was demonstrated.

A type-specific antiserum was prepared against VP 7/8, the major HSV-1 type-specific glycoprotein. The specificity of this antiserum was demonstrated by both neutralization of HSV-1 infectivity and immunoprecipitation followed by SDS-polyacrylamide gel electrophoresis of the immunoprecipitates. Only minimal cross-reactivity with HSV-2 was observed. This major VP 7/8 glycorprotein was also purified from a host of virus-induced proteins with the specific immunoadsorbent prepared with anti-VP 7/8 serum. The one-step purification of this type-specific neutralizing antigen of HSV-1 should allow the development of a sensitive and specific radioimmunoassay.

The deficits in plasma amino acids and serum unesterified fatty acids of cancer patients undergoing chemotherapy and/or radiation therapy were studied to delineate the special requirements of the patients and efficacy of our nutritional therapy. Seven general surgery patients and 13 patients treated by the Head-Neck Service had baseline levels measured as part of their nutritional evaluation prior to surgical treatment of their cancers. Fifteen chemotherapy outpatients maintained on their regular diets had fasting levels analyzed. Twenty-six patients who were admitted for their therapy had their intake of the regular hospital diet supplemented with a low-residue enteral diet formula (Vivonex High Nitrogen Diet); parenteral nutrition was used only if their oral intake was totally inadequate. Baseline and sequential measurements were made of plasma amino acid and serum unesterified fatty acid levels by gas liquid chromatographic techniques. Before operation the patients had normal levels of amino acids except for a significant deficiency of threonine and glycine observed in patients with head-neck tumors. Outpatients with and without hepatic metastases had significantly depressed levels of the essential amino acids valine, leucine, threonine, and methionine and the nonessential amino acids serine, glycine, and proline. The baseline levels of the patients admitted for treatment had similar deficiencies except for more evidence of lysine deficiency. Patients supported with total parenteral nutrition had rapid elevation of the amino acid levels. The patients whose intake was supplemented with the oral diets had improvement in their amino acid levels, but the deficiency in the leucine and threonine fractions persisted up to 4 weeks of therapy. Although the lysine levels were normal when first analyzed, significant differences developed in the patients without hepatic metastases after the start of chemotherapy with return to normal only after chemotherapy was discontinued. Fatty acid levels were not significantly different between the cancer groups except for preoperative elevated oleic acid levels noted in the general surgery tumor group; there were no deficiencies in the essential fatty acids. These studies indicate a need for enteral formulas with adequate branched-chain amino acids and enrichment with threonine and lysine for supplementing the nutrition of the cancer patient who is undergoing chemotherapy.