Complementary Heat Research Articles

Drying of Foamed Biological Materials: Opportunities and Challenges

An overview is provided on hot air drying of foamed materials in a thin layer (foam-mat drying), foam-spray drying, microwave-assisted drying of liquid foams, as well as microwave drying of frozen foams with and without dielectric solid inserts, used as complementary heat sources. In particular, the mechanisms of heat and moisture transport during the drying of foams are identified. The effects of foam characteristics (e.g., foam density and stability) and drying conditions (temperature, air velocity) on drying kinetics and product quality are examined, and the differences between the drying of non-foamed and foamed materials are discussed.

Changes in the Cellular and Organismal Stress Responses of the Subtropical Fish, the Indo-Pacific Sergeant, Abudefduf vaigiensis, due to the 1997–1998 El Niño/Southern Oscillation

There are accumulating reports showing that the El Nino/Southern Oscillation (ENSO) has a significant effect on the population dynamics of marine fishes. However, the influence of ENSO on the physiology of fishes, as possible components of those ecological changes in fish populations, is not fully understood. This study investigated the cellular, physiological, and organismal stress responses in a wild fish population under natural thermal stress. The sea surface temperature at the subtropical ocean of Okinawa, Japan, was the highest in the last 10 years (>32°C) during the summer of 1998 with a strong ENSO. To examine the effects of those unusually warm ocean temperatures on fish, we compared tissue 70-kDa heat shock protein (HSP70) levels and growth rates between the ENSO summer of 1998 and the normal summer of 1999 in a common fish species in Okinawa, the Indo-Pacific sergeant, Abudefduf vaigiensis. We also conducted a complementary heat shock experiment in the laboratory. The field collected Indo-Pacific sergeant had significantly higher muscle HSP70 levels in 1998 than 1999. Higher muscle HSP70 and plasma cortisol levels were observed at 32°C than at 28°C in the laboratory heat shock experiment, indicating that the highest summer ocean temperature in 1998 was sufficient for the fish to up-regulate the cellular and physiological stress responses. In support of this effect, otoliths showed slower growth rates of the fish during the summer of 1998; this may reflect the significant energetic cost of these stress responses.

Monolayers of C 2Cl 2F 4 and C 2ClF 5 physisorbed on graphite

Mono- and submonolayers of the haloethanes C 2Cl 2F 4 and C 2ClF 5 physisorbed on exfoliated graphite have been investigated by X-ray diffraction and by some complementary heat capacity and ellipsometric measurements. Both adsorbates have an orientationally disordered “plastic” mesophase with an incommensurate triangular center-of-mass lattice at intermediate temperatures which gradually melts into the 2D liquid. At low temperatures they freeze into a 2D orientational glass. For C 2ClF 5 the glassy state is in competition with a 4 × 4 phase with a 120 “antiferromagnetic”-type orientational order.

Prevalence of coaggregation reactions among chicken lactobacilli.

Interbacterial adherence was frequently encountered among chicken lactobacilli. Fourteen of 45 combinations involving nine adhering strains were shown to be coaggregative. The coadherence mechanism was mediated by complementary heat- and sonication-sensitive cell surface structures. It was shown that intrageneric adherence enabled lactobacilli to maintain higher numbers in fed-batch reactors simulating the gastrointestinal tract. The mechanism of coaggregation can substantially increase the colonization potential of lactobacilli in environments with short residence times.

Rates of fluid expulsion across the Northern Cascadia Accretionary Prism: Constraints from new heat row and multichannel seismic reflection data

One hundred and ten closely spaced probe heat flow measurements provide new constraints on the thermal regime of the northern Cascadia accretionary sedimentary prism off Vancouver Island. Complementary heat flow values have been obtained from the depth of a bottom‐simulating seismic reflector (BSR) that is interpreted to mark the thermally controlled base of a methane hydrate layer. The only local heat flow variations observed are associated with a sediment slump that is seen in SeaMARC II acoustic images and with the outcrop of several major thrust faults. These anomalies appear to be the result of material displacement only; strong localized fluid flow along faults or elswhere is not evident in the probe or BSR results. Fluid expulsion resulting from the dewatering of the prism sediments appears to occur regionally in the 10–20‐km‐wide zone landward of the deformation front. In this area there is a significant disagreement between the probe and BSR heat flow estimates (roughly 30%) that can be explained by a regionally uniform vertical fluid flow at a rate of about 8×10−10 m s−1. This is in good agreement with the estimated fluid expulsion rate required by the decrease in porosity landward of the deformation front, as estimated from the increase in seismic velocities derived from multichannel reflection data. The heat flow in Cascadia Basin seaward of the deformation front, corrected for the effect of sedimentation, is in excellent agreement with that predicted by cooling plate models. Landward, there is a regional trend of decreasing heat flow across the accretionary prism, which is consistent with a model of simple tectonic thickening. Temperatures at the top of the oceanic crust are estimated to be over 200°C beneath the 2–3 km of sediment in Cascadia Basin. Temperatures at the interface between the prism and the oceanic crust continue to increase landward, and reach 400°–450°C beneath the middle to inner continental shelf. Initiation of megathrust earthquake failure along the main subduction thrust may be thus restricted by the high temperatures to the zone beneath the continental slope and outer shelf. Early and shallow metamorphism of the prism material probably is another important consequence of the early deep burial of the young oceanic crust in this setting.

Heat transfer, pressure drop, and fluid flow patterns in yawed tube banks

Complementary heat transfer, pressure distribution, and flow visualization experiments were performed to investigate the effect of yaw on both staggered and in-line tube tanks. The heat transfer measurements were carried out on a row-by-row basis, and pressures were measured internal to the tube banks as well as upstream and downstream. Air was the heat transfer fluid. The visualization experiments revealed that yaw markedly affected the manner in which the flow impinged on the tubes of the in-line array, with a lesser effect of yaw on the flow field in the staggered array. At a given freestream Reynolds number, the Nusselt number generally decreased as the angle of yaw increased. The yaw effect was well correlated for the staggered array, but not so well for the in-line array because of the aforementioned flow field modifications. The in-line-array Nusselt numbers generally exceeded those for the staggered array, a trend which was accentuated at larger yaw. The pressure drop decreased with increasing yaw. In the present operating range, the in-line-array pressure drops were smaller than the corresponding staggered-array values.

Wall‐to‐bed heat transfer coefficient in gas—liquid—solid fluidized beds

AbstractWall to bed heat transfer has been studied in three‐phase fluidized beds with a cocurrent up‐flow of water and air. Six sizes of glass beads, two sizes of activated carbon beads and one size of alumina beads, varying in average diameter from 0.61 to 6.9 mm and in density from 1330 to 3550 kg/m3, were fluidized in a 95.6 mm diameter brass column heated by a steam jacket. Complementary heat transfer experiments have been performed also for a gas–liquid cocurrent column and liquid–solid fluidized beds.The wall‐to‐bed coefficient for heat transfer in the gas–liquid–solid fluidized bed is evaluated on the basis of the axial dispersion model concept. The ratio of the wall‐to‐bed heat transfer coefficient in the gas–liquid–solid fluidized bed to that in the liquid–solid fluidized bed operated at the same liquid flow rate is correlated in terms of the ratio of the velocity of gas to that of liquid and the properties of solid particles. A correlation equation for estimating the wall‐to‐bed heat transfer coefficient in the liquid–solid fluidized bed is also developed.

Heat Transfer and Pressure Drop Characteristics Induced by a Slat Blockage in a Circular Tube

Complementary heat transfer and fluid flow experiments were performed to determine transfer coefficients and pressure drops associated with the presence of a slat-like blockage in a tube. Water was the working fluid for the heat transfer studies (Pr = 4), while for the fluid flow experiments, which were performed under isothermal conditions, air was employed. The flow was turbulent in all cases, with the Reynolds number ranging from 10,000 to 60,000. Three blockage elements were used which respectively blocked 1/4, 1/2, and 3/4 of the tube cross-sectional area. Downstream of the blockage, heat transfer coefficients were measured around the circumference of the tube as well as along its length. The heat transfer coefficients in the region just downstream of the blockage were found to be several times as large as those for a corresponding conventional turbulent pipe flow. With increasing downstream distance, the coefficients diminish and thermal development is completed (to within five percent) at about 10, 15, and 18 diameters from the respective blockages. The blockage-induced circumferential variations of the heat transfer coefficient are dissipated by about five diameters. The pressure losses induced by the blockage are high, with values for the respective blockages that are 1.2, 5.2, and 33.2 times the velocity head in the pipe flow in which the blockage is situated. These losses are comparable to those for a gate valve.

Microcalorimetric study of phospholipid binding to human apo-HDL

The binding of lysolecithin and synthetic short-chain lecithins: di-caproyl, di-lauroyl and di-myristoyl lecithins to a human apo-high density lipoprotein (apo-HDL) was followed by microcalorimetry. Complex formation was checked by ultracentrifugal flotation. The binding reaction was very rapid and strongly exothermal. The apparent binding enthalpy ΔH B together with the complex composition were computed from the binding curves. Both quantities were of the same order of magnitude for lysolecithin and for the shorter chain lecithins while the binding of di-myristoyl lecithin was characterized by a more highly exothermal reaction. The structure of the lipid phase strongly influences the enthalpy change. In the case of lysolecithin and of the shorter chain lecithins; which form micellar structures in water, the enthalpy change is mainly due to apoprotein-phospholipid complex formation. The disrupture of the myelin figures formed by the di-myristoyl lecithin accounts for the complementary heat effect. The phospholipid composition of the complexes isolated by ultracentrifugal flotation was lower than that determined by microcalorimetry, due to the presence of high salt concentrations in the ultracentrifuge.

The hydrogen ion equilibria of horseradish peroxidase and apoperoxidase.

1. The reversible proton dissociation equilibria of peroxidase, apoperoxidase and haem-recombined apoperoxidase have been explored in 150mm-potassium chloride at 20 degrees C at pH3-11.5. 2. Complementary heat measurements have been made of the classes of titratable groups to determine their intrinsic DeltaH dissociation. 3. These curves are interpreted as showing that there are two histidine residues capable of titration in peroxidase whereas there are three such in apoperoxidase. 4. Concomitant spectroscopic investigations indicate profound differences in the tyrosine ionizations in the two proteins. In peroxidase one group only of the five residues ionizes up to pH11.5. In apoperoxidase four residues are titratable. 5. Spectroscopic titration in 6m-guanidinium chloride and 150mm-potassium chloride reveal one tyrosine residue fewer in peroxidase than in apoperoxidase. 6. These findings are discussed in terms of the ;side chain' groups responsible for binding the haem group in peroxidase. A proximal imidazole group seems probable as is also the involvement of a distally placed tyrosine. 7. The differences between apo- and holo-peroxidase are stressed, particularly in respect of abnormal carboxyl group titration in the former.

The thermal expansion of rubidium chloride at low temperatures

Measurements of the linear thermal expansion coefficient of rubidium chloride are reported between 30 and 260 K. The results are believed to be accurate to within 1% down to 200 K, falling to 2% at 30 K. The Gruneisen parameter gamma = beta VKT/Cv has been shown to fall monotonically from a high temperature limiting value of 1.46. The quasiharmonic approximation has been applied to these and complementary heat capacity and elasticity data to calculate the moments of the vibrational frequency distribution and their volume dependence, interpolation being employed at the lowest temperatures. The results of these calculations conform to the pattern of behaviour which has emerged from earlier comparative studies of sodium and potassium halides.