Direct Heating Effect Research Articles

Infrared Interferometric Measurements of the Near-Surface Air Temperature over the Oceans

Abstract The radiometric measurement of the marine air temperature using a Fourier transform infrared spectroradiometer is described. The measurements are taken by the Marine-Atmospheric Emitted Radiance Interferometer (M-AERI) that has been deployed on many research ships in a wide range of conditions. This approach is inherently more accurate than conventional techniques and can be used to determine some of the error characteristics of the standard measurements. Examples are given from several cruises ranging from the Arctic to the equatorial Pacific Oceans. It is shown that the diurnal heating signal in radiometric air temperatures in the tropical Pacific can typically reach an amplitude of ∼15% of that measured by conventional sensors. Conventional data have long been recognized as being contaminated by direct solar heating and heat island effects of the ships or buoys on which they are mounted, but here this effect is quantified by comparisons with radiometric measurements.

Long-chain conversion of [13C]linoleic acid and α-linolenic acid in response to marked changes in their dietary intake in men

We studied the long-chain conversion of [U-13C]alpha-linolenic acid (ALA) and linoleic acid (LA) and responses of erythrocyte phospholipid composition to variation in the dietary ratios of 18:3n-3 (ALA) and 18:2n-6 (LA) for 12 weeks in 38 moderately hyperlipidemic men. Diets were enriched with either flaxseed oil (FXO; 17 g/day ALA, n=21) or sunflower oil (SO; 17 g/day LA, n=17). The FXO diet induced increases in phospholipid ALA (>3-fold), 20:5n-3 [eicosapentaenoic acid (EPA), >2-fold], and 22:5n-3 [docosapentaenoic acid (DPA), 50%] but no change in 22:6n-3 [docosahexanoic acid (DHA)], LA, or 20:4n-6 [arachidonic acid (AA)]. The increases in EPA and DPA but not DHA were similar to those in subjects given the SO diet enriched with 3 g of EPA plus DHA from fish oil (n=19). The SO diet induced a small increase in LA but no change in AA. Long-chain conversion of [U-13C]ALA and [U-13C]LA, calculated from peak plasma 13C concentrations after simple modeling for tracer dilution in subsets from the FXO (n=6) and SO (n=5) diets, was similar but low for the two tracers (i.e., AA, 0.2%; EPA, 0.3%; and DPA, 0.02%) and varied directly with precursor concentrations and inversely with concentrations of fatty acids of the alternative series. [13C]DHA formation was very low (<0.01%) with no dietary influences.

The Impact of Global Warming on Health and Mortality

Initial concern about the possible effects of global warming on infections has declined with the realization that the spread of tropical diseases is likely to be limited and controllable. However, the direct effects of heat already cause substantial numbers of deaths among vulnerable people in the summer. Action to prevent these deaths from rising is the most obvious medical challenge presented by a global rise in temperature. Strategies to prevent such deaths are in place to some extent, and they differ between the United States and Europe. Air conditioning has reduced them in the United States, and older technologies such as fans, shade, and buildings designed to keep cool on hot days have generally done so in Europe. Since the energy requirements of air conditioning accelerate global warming, a combination of the older methods, backed up by use of air conditioning when necessary, can provide the ideal solution. Despite the availability of these technologies, occasional record high temperatures still cause sharp rises in heat-related deaths as the climate warms. The most important single piece of advice at the time a heat wave strikes is that people having dangerous heat stress need immediate cooling, eg, by a cool bath. Such action at home can be more effective than transporting the patient to hospital. Meanwhile, it must not be forgotten that cold weather in winter causes-many more deaths than heat in summer, even in most subtropical regions, and measures to control cold-related deaths need to continue.

Analysis of the OECD/NRC BWR Turbine Trip Transient Benchmark with the Coupled Thermal-Hydraulics and Neutronics Code TRAC-M/PARCS

An analysis of the Peach Bottom Unit 2 Turbine Trip 2 (TT2) experiment has been performed using the U.S. Nuclear Regulatory Commission coupled thermal-hydraulics and neutronics code TRAC-M/PARCS. The objective of the analysis was to assess the performance of TRAC-M/PARCS on a BWR transient with significance in two-phase flow and spatial variations of the neutron flux. TRAC-M/PARCS results are found to be in good agreement with measured plant data for both steady-state and transient phases of the benchmark. Additional analyses of four fictitious extreme scenarios are performed to provide a basis for code-to-code comparisons and comprehensive testing of the thermal-hydraulics/neutronics coupling. The obtained results of sensitivity studies on the effect of direct moderator heating on transient simulation indicate the importance of this modeling aspect.

FRC Formation Process of Two Colliding Spheromaks with Counterhelicity

A merging formation of field-reversed configuration (FRC) has been studied for the first time without central conductor, using two merging spheromaks with opposing toroidal magnetic field. Without the n=1 stabilization effect of the central conductor, the merging process was maintained stably probably due to (1) plasma flow shear generated by the counterhelicity reconnection and (2) line-tying effect of the magnetic field lines. This relaxation from the force-free (≈0.05-0.1) spheromaks to the high-beta (≈0.7-1) FRC is attributed to efficient (≈80%) conversion of the toroidal magnetic energy of the former to the ion thermal energy of the latter. This energy conversion was caused by a direct ion heating and acceleration effect of reconnection under the toroidally symmetric condition. This ion heating energy was found to increase inversely with the field amplitude parallel to the X-point line. Further plasma acceleration by high-field compression was observed to increase the reconnection speed, revealing the new fast reconnection mechanism called the current sheet ejection.

Direct current heating effects on Si(111) vicinal surfaces

Study on new types of step instability on a Si(111) vicinal surface inducedby the direct current heating effect by reflection electron microscopy andoptical microscopy is reviewed. One step instability is in-phase step wanderingand the other is a periodic step density wave (PSDW). The former is due toelectromigration of Si adatoms and steps are aligned in phase without changing meanstep–step distance. This instability occurs at temperatures between 1000 and1200 °C,under the step-down current heating condition. Steps are in the sinusoidal shape and theirwavelength is in the micron order. The wavelength does not depend on the mean step–stepdistance or off-angle of the vicinal surface nor annealing time. The latter is induced by Auadsorption under step-down current heating at temperature between 830 and930 °C where extremely straight step bands and Si(111) terraces are aligned periodically. Thedriving force of the PSDW is the modification of step structure due to electromigration ofAu adatoms. These phenomena might be useful for micro-fabrication of surface fromthe industrial point of view as well as interesting from the fundamental point ofview.

In-phase step wandering on Si(111) vicinal surfaces: Effect of direct current heating tilted from the step-down direction

In-phase step wandering (IPSW), a newly found step instability due to step-down dc heating on Si(111) vicinal surfaces [Jpn. J. Appl. Phys. 38, L308 (1999)], is studied in detail in the case of dc heating not parallel to the step-down direction, including the time evolution of IPSW. The nucleation and growth of IPSW regions and the reorientation of ridges of IPSW from the step-down direction to the current direction, resulting in the asymmetric wandering of individual steps, are observed. The effects of the current component parallel to the step-down direction and perpendicular to it (parallel to the step direction) are discussed. As a special case an effect of dc heating parallel to the step direction is also studied.

Improvement of Transcription Property of Fine Surface Shape Using Rapid Heating Mold in Injection Molding.

The fine surface pattern, consisting of numerous sub-micron pits on a stamper are transcribed on surfaces of polymer disks in the production of optical disks using an injection molding. Most of the optical disks has been produced with precise transcriptions ; however, miss-transcriptions are observed when the disk is produced at low mold temperature. On the other hand, It is important to produce the disks at low mold temperature in terms of shortening a cooling time and improving the efficiency of production. This paper describes the effect of direct current heating of a stamper on the transcription properties of fine pattern. A model stamper consisting of a stainless steel film was prepared, then the transcription effects were investigated at various injection molding conditions. Not only the experimental results but also the numerical simulation results on the growth of a frozen layer of polymer during injection molding revealed that a rapid heating of the stamper at the filling stage significantly improves the transcription property and also has an effect to reduce the cycle time.

Differential effects of in vitro and in vivo hyperthermia on the production of interleukin-10.

To determine whether hyperthermia activates an anti-inflammatory response. A prospective study. Heatstroke Center, Makkah, and King Faisal Specialist Hospital, Riyadh, Saudi Arabia. Twenty-five heatstroke patients pre-cooling (rectal temperature 42.4 +/- 0.8 degrees C) (group 1) and 13 normothermic heat-stressed subjects were studied (group 2). Twelve of the 25 heatstroke patients were also studied post-cooling (group 3). Mononuclear cells from six healthy blood donors resting at 24 degrees C were used for in vitro study. Mononuclear cells were cultured at a concentration of 1 x 10(6)/ml without and with lipopolysaccharide (LPS) added at concentration of 10, 100, and 1000 ng/ml. The cells were incubated for 24 h at 37, 39, 41, and 43 degrees C. ELISA was used to measure IL-10 in the supernatant and plasma from heatstroke and heat-stressed subjects. All patients in group 1, 40% of group 2, and 37% of group 3, showed elevation of IL-10 (1289 +/- 2519, 248 +/- 393, and 172 +/- 226 pg/ml, respectively) compared with normal control levels, (< 100 pg/ml) P < 0.05. IL-10 level on admission did not correlate with degree of hyperthermia. During 24 h incubation at 37 degrees C without LPS, no IL-10 was detected, whereas with 10 ng/ml LPS, monocytes released 658 +/- 291 pg IL-10/10(6) cells. At 39 degrees C and 41 degrees C IL-10 release was decreased to 225 +/- 114, and 245 +/- 90 pg/10(6) cells, respectively; and was completely inhibited at 43 degrees C (67 +/- 10 pg/10(6) cells), P < 0.0001. Heat-stress with and without hyperthermia is associated with anti-inflammatory response in vivo. However, it does not seem to be the direct effect of heat on monocytes, suggesting that other environmental or genetic factors may be involved.

The effect of direct and indirect hand heating on finger blood flow and dexterity during cold exposure

1. The aim of this study was to investigate if finger temperature or finger blood flow is the critical factor for maintenance of finger dexterity during cold exposure. 2. Subjects were exposed twice to −25°C air for 3 h by using a Torso Heating Test (THT) where the torso was maintained to 42°C with a heating vest while the hands were bare, and a Hand Heating Test (HHT) where the hands were heated with heated gloves. 3. Despite similar finger temperatures, finger blood flow was eight times lower and finger dexterity was decreased in HHT as compared to THT. 4. It is concluded that finger blood flow is the critical factor to maintain finger dexterity in the cold.

Use of coupled ozone fields in a 3-D circulation model of the middle atmosphere

Abstract. With a detailed chemistry scheme for the middle atmosphere up to 70 km which has been added to the 3-D Karlsruhe simulation model of the middle atmosphere (KASIMA), the effects of coupling chemistry and dynamics through ozone are studied for the middle atmosphere. An uncoupled version using an ozone climatology for determining heating rates and a coupled version using on-line ozone are compared in a 10-month integration with meteorological analyses for the winter 1992/93 as the lower boundary condition. Both versions simulate the meteorological situation satisfactorily, but exhibit a too cold lower stratosphere. The on-line ozone differs from the climatological data between 20 and 40 km by exhibiting too high ozone values, whereas in the lower mesosphere the ozone values are too low. The coupled model version is stable and differs only above 40 km significantly from the uncoupled version. Direct heating effects are identified to cause most of the differences. The well-known negative correlation between temperature and ozone is reproduced in the model. As a result, the coupled version slightly approaches the climatological ozone field. Further feedback effects are studied by using the on-line ozone field as a basis for an artificial climatology. For non-disturbed ozone conditions realistic monthly and zonally averaged ozone data are sufficient to determine the heating rates for modelling the middle atmosphere.Key words. Atmospheric composition and structure (middle atmosphere · composition and chemistry) · Meteorology and atmospheric dynamics (middle atmosphere dynamics).

Use of coupled ozone fields in a 3-D circulation model of the middle atmosphere

With a detailed chemistry scheme for the middle atmosphere up to 70 km which has been added to the 3-D Karlsruhe simulation model of the middle atmosphere (KASIMA), the effects of coupling chemistry and dynamics through ozone are studied for the middle atmosphere. An uncoupled version using an ozone climatology for determining heating rates and a coupled version using on-line ozone are compared in a 10-month integration with meteorological analyses for the winter 1992/93 as the lower boundary condition. Both versions simulate the meteorological situation satisfactorily, but exhibit a too cold lower stratosphere. The on-line ozone differs from the climatological data between 20 and 40 km by exhibiting too high ozone values, whereas in the lower mesosphere the ozone values are too low. The coupled model version is stable and differs only above 40 km significantly from the uncoupled version. Direct heating effects are identified to cause most of the differences. The well-known negative correlation between temperature and ozone is reproduced in the model. As a result, the coupled version slightly approaches the climatological ozone field. Further feedback effects are studied by using the on-line ozone field as a basis for an artificial climatology. For non-disturbed ozone conditions realistic monthly and zonally averaged ozone data are sufficient to determine the heating rates for modelling the middle atmosphere.Key words. Atmospheric composition and structure (middle atmosphere · composition and chemistry) · Meteorology and atmospheric dynamics (middle atmosphere dynamics).

Sensitivity of Drosophila Heat Shock Transcription Factor to Low pH

The heat shock transcription factor (HSF) mediates the induction of heat shock gene expression. The activation of HSF involves heat shock-induced trimerization, binding to its cognate DNA sites, and the acquisition of transcriptional competence. In this study, the oligomeric properties of Drosophila HSF were analyzed by equilibrium analytical ultracentrifugation and gel filtration chromatography. Previous findings showed that trimerization of purified Drosophila HSF was directly sensitive to heat and oxidation (1). Here we report that low pH, in the physiological range, also directly induces HSF trimerization and DNA binding in vitro. Furthermore, the induction of HSF trimerization by low pH is synergistic with the actions of heat and oxidation. Since heat or chemical stress leads to a moderate decrease of intracellular pH, we suggest that intracellular acidification may contribute to activating the heat shock response in vivo.

Effects of direct and indirect heating on the validity of rock weathering simulation studies and durability tests

Rock surface and subsurface temperature responses in samples exposed to direct heating (insolation) under natural hot desert conditions reveal considerable variability between lithologies related to differences in thermal properties, especially albedo and thermal conductivity. However, when the same samples are heated indirectly by air in an oven-based environmental cabinet, lithological differences in temperature response disappear and all samples attain temperatures similar to the air temperature within the cabinet. Rates and patterns of rock decay produced in such environmental cabinets may not, therefore, reflect those encountered under natural conditions, where breakdown is related to micro-environmental conditions at the rock/air interface and where rock temperature is one of the most important controlling factors. In addition to implications for assessment of weathering effectiveness, use of only indirect forms of heating affects the determination of comparative rock durability because all rock types are cycled through the same temperature regimes. Because temperature exerts such a major control on rock breakdown through its control on physical and chemical weathering processes, all significant factors influencing it must be included in the design of weathering simulations and durability tests.

Experiments to investigate DCH phenomena with large-scale models of the Zion and Surry nuclear power plants

The Surtsey Test Facility and the Containment Technology Test Facility (CTTF) at Sandia National Laboratories (SNL) have been used to perform scaled experiments for the Nuclear Regulatory Commission (NRC) that simulate high-pressure melt ejection (HPME) accidents in a nuclear power plant (NPP). These experiments are designed to investigate the effects of direct containment heating (DCH) phenomena on the containment load. High-temperature, chemically reactive alumino (thermitic) melt is ejected by high-pressure steam into a scale model of either the Zion or Surry NPP. Integral effects tests under prototypic conditions have been performed to investigate the effects of dispersal of molten core materials on DCH loads, and to study the effects of Westinghouse plant configurations on DCH loads. In Westinghouse plants, there is (1) an intermediate compartment that is large compared with the reactor cavity but small compared with the main containment volume, and (2) no significant line-of-sight pathway for debris transport from the cavity to the main containment volume. Containment compartmentalization is the dominant mitigating feature for Zion, Surry, and most other pressurized water reactors. Experimental results will be used to further assess the applicability of existing DCH models to Westinghouse plants on DCH loads.

Mathematical analysis of haemodilution's direct effect on rate of brain cooling during cardiopulmonary bypass

Cerebral hypothermia is the principal means of providing neurologic protection during cardiac surgery. Better understanding is needed of ways to improve brain cooling during bypass. The goal of this study is to find whether haemodilution has a significant direct effect on the rate of brain cooling, from changes in the blood's thermal properties. The brain is cooled during hypothermic cardiopulmonary bypass, almost exclusively, by the colder blood. We use the corresponding component of the bioheat transport model to predict the proportional direct effect of changing blood density and specific heat on the amplitude of the rate of brain cooling. We find that haemodilution can significantly change blood density and specific heat. For example, haemodilution with the fluorocarbon emulsion AF0104 from a haematocrit at 45% to a haematocrit at 22% increases blood density by 18%, and decreases specific heat by 21%. Nevertheless, the mathematical model predicts that the direct effect of haemodilution on the rate of brain cooling by the cold blood is small; +7%, +6% and -7% for normal saline, 5 g dl-1 albumin in normal saline, and AF0104 fluorocarbon emulsion, respectively. We conclude that, within the haemotocrit range used clinically during bypass, haemodilution with these substances has only a small direct effect on the rate of brain cooling.

Behaviour of α-AI2O3 insulator surfaces under electron irradiation

Cathodoluminescence (CL), Auger electron spectroscopy (AES) and direct crack measurements were performed onα-Al2O3 samples in order to relate chemical, electrical and mechanical effects induced by electron irradiation of the surface. Electrical discharges and visible luminescence were observed during the excitation of the samples with a 80 keV electron beam. Changes of the surface state and of the toughnessKIc were subsequently detected. The results suggest that charging of the sample is related to the presence of defects and corresponding trap levels in the energy gap. The concentration of defects (oxygen vacancies or associated F, F+ centres) may be enhanced, especially in the vicinity of the surface, by the electrical discharges induced by the electron irradiation. This leads to an increase of mechanical stresses in the brittle material: a striking example was the fracture of a corundum single crystal in the electron microscope, which cannot be explained by the direct heating effect of the primary electron beam. On the contrary, an advantageous situation for the mechanical properties of the material may be achieved when the defects have a blocking effect on the crack propagation; a subsequent increase of the toughnessKIc is then recorded.

MATHEMATICAL ANALYSIS of CRITICAL PARAMETERS IN ASEPTIC PARTICULATE PROCESSING SYSTEMS

ABSTRACTA sensitivity analysis of a one‐dimensional heat transfer model for a heat‐hold‐cool aseptic system of food products containing particulates was completed for eighteen different design, product, and process control parameters. All of the parameters, except the direct effect of the fluid specific heat, were determined to be statistically significant in influencing the accumulated lethality of the processes. the most influential parameters were surface heat transfer coefficient in the hold tube at the fluid‐particle interface, exit temperature of the fluid from the heater, initial temperature, holding tube size, and holding tube‐U value. the process/product‐related parameters that are significant in the establishement of a process are: particle diameter, surface heat transfer coefficient in the hold tube at the fluid‐particle interface, thermal properties of the fluid and particulates, maximum heater velocity ratio, maximum hold tube velocity ratio, surface heat transfer coefficient in the heater at the fluid‐particle interface, product flow rate, and particle to fluid ratio.

Embryonic and maternal heat shock responses to a teratogenic hyperthermic insult

Exposing embryos to elevated temperatures both in vivo and in vitro has been to result in the production of offspring with severe congenital abnormalities. While a direct effect of heat cannot be excluded, recent interest has been focused on the possible role that the induction of the heat shock response may have in the etiology of the observed congenital defects. In the present study, mouse embryos from inbred strains known to differ in terms of their sensitivity to heat-induced exencephaly were treated in vivo and their heat shock response determined using SDS-PAGE electrophoretic techniques. Further, the embryonic response were compared with a maternal cell type. We observed excellent agreement between the two test systems following exposure to a teratogenic hyperthermic insult. Both the embryonic and maternal cells underwent a reduction in total protein synthesis and an enhanced synthesis of four heat shock proteins migrating with the molecular weights of 68, 70, 97, and 110 kDa. The results failed to indicate any strong correlation between the heat shock response and enhanced genetic sensitivity to hyperthermia-induced neural tube defects.

The influence of hyperthermiain vitro on the functions of peritoneal macrophages in mice

Total-body hyperthermia (TBHT) as a treatment for cancer may lead to a reduction in the host's immunocompetence as a result of the direct effects of heat on the immune system. Thus, we studied the influences of hyperthermia in vitro on the function of peritoneal macrophages from mice. Peritoneal macrophages from C3H/HeN mice were heated in vitro for 3 hr at 37, 39, 40, 41 or 42 degrees C. After exposure to heat, the phagocytic ability of the macrophages, as well as results of the nitroblue tetrazolium (NBT) reduction test and the cytotoxicity test were examined. The changes in all these parameters showed almost the same pattern: a tendency for macrophage functions to be potentiated up to 40 degrees C, and a tendency towards inhibited functioning at temperatures above 41 degrees C. Although augmented functions of macrophages were observed after exposure to mild hyperthermia (less than 40 degrees C), the possibility of TBHT (42 degrees C)-induced inhibition of macrophage function must be further investigated in clinical trials of TBHT therapy for cancer.