Surface Trough Research Articles

Thermal Assessment of an Air-Filled Surface Trough for 400 kV Cables

Using a full-scale trough, temperature measurements around the cables and inside the trough yield an empirical formula for heat transfer from the central cable. This, together with assumed solar and wind quantities at the ground surface and the effective thermal resistance of the trough via the soil to ambient, yields the thermal resistance of the cable surface to ambient. Calculation of the current rating of the cables yields a value below the normal buried rating. It is concluded that the air-filled trough has no advantage over the sand-filled variety.

A statistical study of synoptic systems causing significant Rainfall over Tamil Nadu during southwest monsoon Season

A statistical analysis of the five-year data (1975-79) has been carried out to study the occurrence of various synoptic systems which cause significant rainfall (scattered/fairly widespread/.widespread) over Tamil Nadu during the southwest monsoon season. It is seen that the occurrence of the synoptic systems surface trough (with or without upper air cyclonic circulation) and low pressure area- id dependent on the position of the monsoon trough with respect to the normal. There IS a high probability of occurrence of surface trough with cyclonic circulation and low pressure area when the monsoon trough is to the north of Its normal position. Also the probability of occurrence of significant rainfall is higher with low pressure area (66 %) compared to sea level trough with or without cyclonic circulation (20 %).

A Numerical Case Study of East Asian Coastal Cyclogenesis

Abstract The relative importance of latent beat release and surface sensible heat flux in a case of East Asian coastal cyclogenesis were investigated by performing numerical experiments with the ECMWF limited-area model. In the control experiment that included all physical processes, the cyclone developed rapidly in a way similar to that observed. In the experiment without latent beat feedback, only a shallow low appeared when the upper short-wave trough approached the inverted surface trough situated on the coast, but no further development took place. This suggests that the baroclinic forcing was enhanced by the feedback of physical process. An increasingly unbalanced subtropical jet streak, an ageostrophic low-level jet and the associated vertical indirect circulation prior to the major development were well simulated in the Control but they were not simulated in the “dry” experiment (without latent heating). The latent heating had a profound impact on the amplifying jet streak circulation and the vert...

A Langmuir-Blodgett study of the orientation of the cancer photoradiation therapy drug dihematoporphyrin ether at water-air and water-fatty-acid-air interfaces

The fluorescent molecule dihematoporphyrin ether (DHE), which is known to become sequestered in cells and which is currently being used for “photoradiation” cancer therapy in clinical trials, may organize into two-dimensional arrays at a water-membrane interface. Some of the consequences of such ordering could be as follows: (1) to create a light-gathering apparatus in the cell analogous to chlorophyll in photosynthetic units; (2) to participate in the cytotoxicity mechanism of DHE, leading to the detection of anisotropy in the absorption and/or emission of visible light which would allow coupling of (cytotoxic) optical energy to the cell membrane; (3) to enhance the DHE—singlet-oxygen cytotoxicity mechanism considered to be operative in cancer cells. We present here evidence for the existence of these arrays, based on evaluation of surface pressure vs. trough area data, polarized and unpolarized visible reflectance spectra on water, and polarized and unpolarized UV-visible spectra on glass. Preliminary conclusions are as follows. 1. (1) DHE forms a film at water-air and water-fatty-acid-air interfaces and probably lies with its ring planes parallel to the water in an “overlapped” configuration. 2. (2) A shift from one absorbing species of DHE to another may occur at the water-air interface during compression experiments. 3. (3) DHE orientation at an interface may be affected by fatty acid present at the interface. 4. (4) A preferential orientation of DHE oscillators probably exists on a solid support. We investigate the analogy between DHE and the light-gathering chlorophyll photosynthetic unit, and the anisotropic (directional) capabilities of ordered DHE in Langmuir-Blodgett films and cells.

Interaction of polypeptide hormones with lipid momolayers

1. The interaction between lipid monolayers spread on the surface of water and oxytocin, [8-arginine]-vasotocin and [1-asparagine-5-valine]-angiotensin II in the subphase was investigated in a Langmuir surface trough by studying the changes in pressure produced on injection of various quantities of the polypeptide solution under the film. 2. The effect of 2m- and 4m-urea on the character of the adsorption is reported. 3. Structures for the adsorbed films formed in this way are suggested. 4. If the lipid monolayer is taken as a suitable model of cell membranes, then it may be supposed that the effect of such structures forming in cell membranes would be to provide effective ;pores' to facilitate the movement of water and other small molecules across the membrane.

Effects of gestation and prenatal asphyxia on pulmonary surface properties of the foetal rabbit.

1. The pulmonary surface properties of foetal rabbits were studied after delivery by Caesarean section at 26-30 days and after normal delivery at term (31 days).2. Quasi-static pressure-volume curves were defined for the lungs and the surface properties of the same lungs were further studied both by the bubble-stability method and by means of a surface balance and trough. Results given by each method are compared and discussed.3. At the 26th day of gestation the pulmonary surface properties, characteristic of the animal at term, were not yet present. These properties were first evident on the 28th day.4. A period of 16 min intense prenatal asphyxia on the 28th day of gestation failed to produce a change in pulmonary surface properties.

Molecular interaction of aromatic hydrocarbons in lipid monolayers

The interaction of six aromatic hydrocarbons with cholesterol and lecithin has been studied, using a mixed monolayer technique, on a Langmuir surface trough. The hydrocarbons associate with cholesterol and lecithin in such films to a limited extent, after which additional hydrocarbon does not contribute to the area of the film, but forms an excess solid phase. The association has been treated in terms of a solubility of the hydrocarbon in a two-dimensional solution and compared with data obtained from phase equilibria studies. Pressure separation of the hydrocarbon occurs at a pressure at which the partial molar free energy of the hydrocarbon in the film equals the saturated partial molar free energy.

Adsorption of Octapeptide Hormones on to Lipid Monolayers

THE interaction between lipid monolayers spread on the surface of water, and oxytocin and vasotocin (arginine vasotocin) in the substrate, has been investigated, using a Langmuir surface trough, by studying the changes in pressure produced on injection of various quantities of the polypeptide solution under the film. This technique is similar to that used for the study of the interaction between protein in the substrate and lipid monolayers1,2.

Surface viscosities of mixed unimolecular films

Variations of the surface viscosities with surface pressure of binary mixed monolayers of stearic acid with octadecanol and with arachidic acid were measured. A torsional surface viscometer was employed together with a horizontal-type film balance and a surface trough which was maintained at 25.00°C. The observed fluidities indicated that homogeneous surface solutions were formed throughout the entire composition ranges of both mixtures. The long-chain fatty acid mixtures appeared to give nearly perfect monolayer solutions, whereas complex intermolecular interactions occurred in the acid + alcohol solutions.

Protein interactions with lecithin and cephalin monolayers

A surface trough has been used to study protein/lipid interactions by a development of the Schulman-Rideal injection technique. From the adsorption isotherms obtained the structure of the complexes has been determined. The lipids used—distearin, dipalmitoyl cephalin, and distearoyl lecithin—were synthetic materials, and the proteins were bovine plasma albumin and sheep insulin. The results indicated that the first sublayer of adsorbed protein combined with distearin and cephalin through the peptide bonds, probably by means of hydrogen bonding or ion-dipole association. With lecithin, however, the interaction appeared to be ionic. In all cases the indications were that a second layer of native protein was adsorbed.

Protein interactions with lecithin and cephalin monolayers

A surface trough has been used to study protein/lipid interactions by a development of the Schulman-Rideal injection technique. From the adsorption isotherms obtained the structure of the complexes has been determined. The lipids used—distearin, dipalmitoyl cephalin, and distearoyl lecithin—were synthetic materials, and the proteins were bovine plasma albumin and sheep insulin. The results indicated that the first sublayer of adsorbed protein combined with distearin and cephalin through the peptide bonds, probably by means of hydrogen bonding or ion-dipole association. With lecithin, however, the interaction appeared to be ionic. In all cases the indications were that a second layer of native protein was adsorbed.