Immersion In Fresh Water Research Articles

Thermoregulation, cardiovascular regulation and thermal sensation in thermoneutral CO2 water immersion in humans

CO2 water immersion at 1000 ppm affects thermoregulation through the increased cutaneous blood flow on the immersed skin area. However, the effect of CO2 water immersion on cardiovascular function remains to be clarified in humans. To examine whether CO2 bathing affects cardiac autonomic function, we analyzed heart rate variability and measured the cardiac output by Echo (Apio XV, Toshiba, Japan) during CO2 and fresh water immersion. Tympanic temperature (thermistor thermometry), cutaneous blood flow (laser-Doppler flowmetry) and electrocardiogram (ECG) were monitored continuously. The subjective thermal and comfort sensations were asked every 10-min during experiments. After a rest for 10 min, the subject immersed up to the breast level to CO2-rich water at 1000ppm or fresh water at thermoneutral water. Spectral analysis of R-R interval was performed using a maximal entropy method to obtain high (HF) and low frequency (LF) components (HF: 0.15–0.40 Hz and LF: 0.04–0.15 Hz, respectively). The results were shown as follows: 1) HF was significantly higher in CO2 water immersion than in fresh water immersion. 2) LF/HF ratio was significantly lower in CO2 waterimmersion than in fresh water immersion. 3) Tympanic temperature was significantly lower during CO2 water immersion than during fresh water immersion. 4) Cutaneous blood flow in immersed forearm was significantly higher during CO2 water immersion than during fresh water immersion. 5) The thermal sensation scores were warmer in CO2 water immersion than in fresh water immersion. It was suggested that CO2 water immersion inhibits cardiac sympathetic nerve activity, probably via increasing of skin warm sensitive neurons in humans.

Hygrothermal ageing effects on FRP laminate and structural foam materials

A programme of dynamic mechanical thermal analysis (DMTA) tests is presented, which was carried out on FRP laminate and PVC foam materials typical of those employed in the sandwich construction of marine craft. The results are compared for as-manufactured material and material that had been aged by fresh water immersion at 40 and 60 °C, in order to determine the evolution of storage modulus, loss modulus, tan δ and glass transition temperature with increasing length and severity of hygrothermal exposure. It was found that plasticisation induced a progressive reduction in room temperature modulus, but there was also evidence of an antiplasticisation process and postcure caused by the elevated temperature immersion, which was revealed upon drying during the DMTA temperature ramp.

Determination of the Moisture Uptake Mechanism in Closed Cell Polymeric Structural Foam during Hygrothermal Exposure

Polymer composite sandwich construction is increasingly used in the fabrication of marine craft where high specific strength and stiffness are required. While the moisture uptake behaviour of thermoset resins and their fibre-reinforced composites has been the focus of much research, the mechanisms of moisture absorption in foam core materials have received little attention. This paper presents a programme of work carried out to determine the moisture uptake mechanisms in closed cell PVC foam under fresh-water immersion. A comprehensive understanding of the ageing mechanism for the foam has been proposed. A multi-stage process was observed, which exhibited an initial mass increase that was linear with respect to the square root of time, followed by an apparent saturation plateau, subsequently followed by further increases and plateaus. While diffusion into the polymer cell wall network was found to be the primary mechanism, passage of moisture into cell cavities was also observed. The multi-stage process was attributed to diffusion, influenced by internal stress relaxation and the geometry of the local cell structure. A Fickian one-dimensional diffusion model was found to fit the initial part of the experimental results adequately.

Hygrothermal ageing effects on FRP laminate and structural foam materials

A programme of dynamic mechanical thermal analysis (DMTA) tests is presented, which was carried out on FRP laminate and PVC foam materials typical of those employed in the sandwich construction of marine craft. The results are compared for as-manufactured material and material that had been aged by fresh water immersion at 40 and 60 °C, in order to determine the evolution of storage modulus, loss modulus, tan δ and glass transition temperature with increasing length and severity of hygrothermal exposure. It was found that plasticisation induced a progressive reduction in room temperature modulus, but there was also evidence of an antiplasticisation process and postcure caused by the elevated temperature immersion, which was revealed upon drying during the DMTA temperature ramp.

Initial stages of microbiologically influenced tarnishing on titanium after 20 months of immersion in freshwater.

This paper studies the initial stages of iridescent tarnishes on titanium heat exchanger tubes in contact with running freshwater on the river Tagus in Spain for up to 20 months. Electrochemical impedance spectroscopy (EIS), scanning electron microscopy [(SEM with energy dispersive X-ray (EDX)] and X-ray photoelectron spectroscopy (XPS) in conjunction with argon-ion sputtering were the techniques used. The EIS data indicated a capacitive behavior, showing a semicircle that was better defined as the experimental time increased, indicating a decreasing tarnishing resistance of titanium. XPS and EDX results indicated that the main elements identified were calcium, phosphorus, nitrogen, and iron. The amount of these elements was higher on the tarnished titanium specimens than on the untarnished specimens. SEM analysis showed the presence of diatoms in the iridescent tarnishes on titanium tubes.

Acute pulmonary problems

_ _ pain. 4. Pink puffers is a term used to describe patients with _ _ 8. Open sucking chest wounds allow air to enter the pleural space during _ _ 11. Multiple _ _ transfusions, sepsis, cardiopulmonary bypass, and head injuries are some of the either direct or indirect injuries that can predispose a person to developing adult respiratory distress syndrome. 12. Respiratory failure is defined by arterial blood gases showing low oxygen content of blood denoting hypoxia and a high carbon dioxide denoting _ _ 13. The major risk factor contributing to the development of chronic obstructive disorder is a history o f _ _ 16. Vomiting and regurgitation can result in _ _ 20. The chief complaint of persons presenting with carbon monoxide poisoning is a _ _ 22. With salt water near-drownings you would expect to see a high serum sodium _ _ 24. Precipitating factors contributing to status asthmaticus are often a respiratory infection or an reaction. 28. A term used to describe patients with chronic is blue bloaters. 29. Victims of saltand fresh-water immersion have the same initial presentation of hypoxemia, hypercapnia, and respiratory and/or metabolic 31. You would expect to see _ _ breathing by a person suffering from a flail chest. 34. Without immediate intervention, aspiration of large particles can cause immediate _ _ and death. 35. A common complication of mechanical ventilation is _ _ pneumonia. 36. Deep vein thrombosis in the lower extremities predisposes patients to development of a pulmonary _ _ 37. The three most common complaints of patients with a embolus are: tachypnea, and pleuritic chest pain. 38. Adult respiratory distress syndrome patients who develop this complication have a 90% mortality rate. 39. Carbon dioxide has a much higher affinity for the _ _ molecule than oxygen.

Restriction Fragment Length Polymorphism (RFLP) Analysis on DNA from Human Compact Bone

DNA typing techniques primarily identify specific genetic markers that are highly polymorphic within a population and have found great utility in forensic science. The established DNA identification protocol, termed restriction fragment length polymorphism (RFLP), has been admitted as physical evidence in the investigation of crimes such as assault, sexual assault, and homicide. The limitation associated with this procedure concerns the integrity of the genetic material. This study sought to evaluate human bone as a source material for DNA identification following exposure to common forensic field conditions. Often, with the onset of decomposition and eventual disarticulation of a body, soft tissues, hair and teeth may not be recovered. The significance of this study lies in the fact that, within forensic anthropology, human bone represents the most biologically stable evidence and is sometimes all that remains after periods of exposure. Genomic DNA was extracted from human bone following exposure to surface deposit, shallow burial, and fresh water immersion. Samples were collected over a three month time course and analyzed by spectrophotometry and agarose gel electrophoresis as well as RFLP analysis. The data suggest that high molecular weight DNA may indeed be extracted from human bone and typed by RFLP analysis for use in forensic identification. Under simulated forensic field conditions, the severity of DNA degradation was in the order of fresh water immersion > shallow burial > surface deposit. Genomic DNA from bone deposited on the desert surface for up to 4 weeks was detected by RFLP analysis. No spurious bands were detected in any specimens, and to the extent that bands were still present, the RFLP patterns matched. These findings demonstrate that human bone can be a reliable source of genomic DNA, and that bone recovered from surface deposit is the most desirable for use in forensic identification.

ESEM study of osmotic swelling of bentonite from Radzionkow (Poland)

Swelling tests using an environmental scanning electron microscope (ESEM) have been carried out on bentonite of Carboniferous age from the Radzionkow coal mine, Poland. The bentonite consists mostly of smectite in which sodium is the main exchangeable cation. ESEM test results revealed that in all samples osmotic swelling of constituent smectite in response to freshwater immersion led to significant microstructural reorganisation, similar to that recently recorded for freshwater-treated, smectitic clay in reservoir sandstones. Freshwater exposure caused the bentonite to become significantly less compact and more (micro)porous due to osmotic swelling of constituent smectite.

SWELLING BEHAVIOUR OF MIXED-LAYER CLAYS IN HYDROCARBON RESERVOIRS

The freshwater sensitivity of a variety of mixed-layer illite/smectite and chlorite/smectite clays has been studied with an Environmental Scanning Electron Microscope (ESEM) in order to determine whether all hydrocarbon reservoirs hosting these clays should be regarded as freshwater sensitive. Experimental procedures involved closely comparing in situ mixed-layer clay within selected areas at high magnification before and after prolonged freshwater treatments.The response of smectite-rich illite/smectite (two samples; 10–20 per cent illite interlayers) to freshwater immersion varied greatly. One sample rapidly swelled to many times its original volume to form a pervasive gel that greatly reduced porosity and permeability, whereas the other sample underwent only a subtle morphological change that had little or no adverse effect on reservoir quality. Illite-rich illite/smectite (three samples; 65—>85 per cent illite interlayers) and chlorite-rich chlorite/smectite (two samples; 50 per cent and >70 per cent chlorite interlayers) underwent no morphological change when immersed in freshwater for up to three months, indicating that these clays in sandstones are unlikely to cause formation damage due to swelling if exposed to freshwater-based fluids.

Terrestrial life in isopods: evolutionary loss of gas-exchange and survival capability in water

Survival and oxygen uptake in air and water were investigated in four species of terrestrial isopods, Armadillidium vulgare Latreille, 1804, Porcellio scaber Latreille, 1804, Oniscus asellus Linné, 1758, and Ligia pallasii Brandt, 1833, to compare the degree of vestigial adaptation to aquatic existence versus adaptation to terrestrial existence. Most submerged A. vulgare, P. scaber, and O. asellus died by 18 h, whether in fresh water or isosmotic seawater. Ligia pallasii lived for almost 2 d in fresh water and for at least 25 d in seawater (none died during this time). Oxygen uptake in water was 44 – 66% that in air for the three fully terrestrial species, and 160% that in air for the semiterrestrial L. pallasii. Oxygen consumption of submerged A. vulgare (representative of fully terrestrial forms) declined to 50% after 14 h and to 17% by 24 h, by which time the animals were clinically dead. In comparison, L. pallasii's aquatic oxygen consumption was maintained at normal or higher levels for at least 3 d. All species could survive several hours of immersion in fresh water, sufficient to withstand temporary rain deluge. Ligia pallasii's superior capabilities to survive and respire in seawater reflect its greater similarity to aquatic ancestors, and an evolutionary series showing progressive decline in survival and gas-exchange capability in water would be as follows: L. pallasii > O. asellus > P. scaber ≥ A. vulgare.

ESEM study of illite/smectite freshwater sensitivity in sandstone reservoirs

The water sensitivity of authigenic smectite- and illite-rich illite/smectites in sandstone reservoirs has been investigated using an Environmental Scanning Electron Microscope (ESEM). The ESEM enabled the illite/smectites to be directly observed in situ at high magnification during freshwater immersion, and was also particularly effective in allowing the same selected illite/smectite areas to be closely compared before and after freshwater treatments. The tendency of authigenic smectite-rich illite/smectite to swell on contact with fresh water varies greatly. Smectite-rich illite/smectite may osmotically swell to many times its original volume to form a gel which greatly reduces porosity and permeability, or may undergo only a subtle morphological change which has little or no adverse effect on reservoir quality. Authigenic illite-rich illite/smectite in sandstones does not swell when immersed in fresh water. Even after prolonged soaking in fresh water, illite-rich illite/smectite particles retain their original morphology. Accordingly, illite-rich illite/smectite in sandstones is unlikely to cause formation damage if exposed to freshwater-based fluids.

Behavioral Regulation of Hemolymph Osmolarity Through Selective Drinking in Land Crabs, Birgus latro and Gecarcoidea lalandii.

Drinking behavior in Birgus latro and Gecarcoidea lalandii was videotaped under controlled laboratory conditions. B. latro displayed the drinking behavior typically observed in nature, spooning up water with the chelae (Lister, 1888; Gross, 1955). G. lalandii is documented for the first time displaying this same behavior; however it obtained water primarily through immersion. Under normal hydrated conditions (hemolymph osmolarities < 1050 mOsm) B. latro showed no preference for drinking fresh or seawater. When dehydrated (hemolymph osmolarities > 1050 mOsm) B. latro altered its drinking behavior and showed a distinct preference for freshwater. This strategy resulted in restoration of original hemolymph osmolarities and wet weights and was accomplished through periods of intensive drinking activity. Conversely, G. lalandii never experienced true dehydration; rather, the hemolymph became hyperosmotic compared with control animals. This species preferred freshwater both under normal and hemoconcentrated conditions. G. lalandii was also able to osmoregulate behaviorally and was able to restore hemolymph osmolarities to normal concentrations via immersion in freshwater following experimentally induced hemoconcentration. Possible physiological and ecological reasons for the differences in water uptake strategies and preferences are discussed.

Salinity Tolerance and Osmoregulation in the Nemertean Pseudocarcinonemertes homari, an Egg Predator of American Lobster, Homarus americanus

The salinity tolerance and osmoregulation of Pseudocarcinonemertes homari were determined to develop a method for elimination of this nemertean from egg masses of American lobster, Homarus americanus. The lower and upper lethal salinities (LS50) for nemerteans are 11 and 45‰ at 7 °C and 19 and 37‰ at 14.5 °C. Immersion in freshwater was lethal in 4 min or less, depending on temperature. The nemerteans hyperosmoconformed over the range 10–1600 mosm∙kg−1. Lobster eggs (eye index [Formula: see text]) survived for 2–8 h when immersed in freshwater. Ovigerous lobster were not affected by a 5-min immersion in freshwater and were able to withstand at least 30 min if only the abdomen was immersed. Lobster eggs hatched and larvae developed normally up to at least stage IV, even after a 30-min freshwater immersion. These results suggest that nemerteans could be eliminated from American lobster by immersing their abdomen and attached eggs in freshwater for 5 min and immersing the entire lobster for an additional 5 min.

Cortical alveolus breakdown in the eggs of the freshwater teleost Rhodeus ocellatus ocellatus

Cortical alveoli and their breakdown in the eggs of the rose bitterling were morphologically investigated. Cortical alveoli of various sizes existed in multiple layers within the cortical cytoplasm of each egg. Two types of cortical alveoli were recognized--one possessed homogeneous contents; the other possessed heterogeneous contents with electron-less dense spots. The eggs were activated by a penetrating spermatozoon or by immersion in fresh water. The immersion of the eggs into fresh water induced a wave of cortical alveolus breakdown (CABD), which was propagated from the vegetal pole to the animal pole. When eggs were inseminated in fresh water, CABD progressed from both the vegetal and the animal poles of the egg, and was complete within about 20 min. The contents of the cortical alveoli were released into the perivitelline space through a large opening formed by the fusion of the plasma and cortical alveolar membranes. For a short time after CABD, the smooth inner surfaces of the cortical alveoli were readily discernible from the rougher original plasma membrane. About 30 min after immersion in fresh water, the inner surfaces of the cortical alveoli were indistinguishable from the original egg surfaces. Aequorin-injected eggs became luminescent immediately after their immersion in fresh water. The luminescence reached a maximum level about 15 min later and subsided after roughly 30 min. The result shows that increase in intracellular free Ca ions occurs during CABD.

Residence time of the sea louse, Lepeophtheirus salmonis K., on Atlantic salmon, Salmo salar L., after immersion in fresh water

Returning adult salmon caught at the mouth of the River Dee, Aberdeenshire, were transferred to tanks in the laboratory. For fish placed in fresh water, sea lice remained attached for up to 6 days, though most lice were lost in the first 48 hours. Few lice were lost from salmon maintained in sea water. The experiments were conducted in water within a temperature range of 12·8 to 16° C, equivalent to summer river temperatures in the Aberdeenshire Dee.

Multiple stress tolerance in an antarctic terrestrial arthropod: Belgica antarctica

Terrestrial arthropods of the maritime Antarctic experience a diverse range of environmental Stressors including extended periods of ice and snow cover, anoxia, immersion in water of variable pH and salinity, and extensive habitat drying. The collembolan Cryptopygus antarcticus and the mite Alaskozetes antarcticus seasonally depress whole body supercooling points to avoid the lethal effects of freezing. Alternatively, the wingless chironomid Belgica antarctica has a relatively limited supercooling capacity (between −6 and −8 °C) and tolerates extracellular freezing. The lower limit of freeze tolerance remains unchanged near −13 °C throughout the year in B. antarctica. Summer larvae tolerate dehydration to a limit of 35% of initial body weight as well as extended periods of anoxia and immersion in freshwater and saltwater. Two weeks of exposure to variable pH (3–12) induced no mortality.

Increasing incidence of childhood immersion injury in Brisbane.

The incidence of childhood immersion injury in a defined population is reported. The data were drawn from this Hospital's Child Injury Surveillance programme and cover the period July 1, 1984 to June 30, 1985. The overall rate of immersion injury was 26.8 per year per 100 000 children at risk and the rate for fresh-water immersions was 25.3. The magnitude of this public health problem is revealed by an annual fresh-water immersion rate of 70.2 per 100 000 at risk for the critical 0 to four years' age group. Eighty per cent of all immersions occurred in swimming-pools and the rate of pool immersion is three times that reported in the Brisbane Drowning Study (1971-1975). Eighty per cent of immersions in back yard pools were potentially avoidable by the provision of an effective safety barrier. Only 25% of the families that were involved could be described as being familiar with their pool.

Electron microscopic observations on the process of polar body formation in artificially activated eggs of the rose bitterling

AbstractMature eggs were obtained from adult female rose bitterling, Rhodeus ocellatus ocellatus. Both intact and dechorionated eggs were activated by immersion in freshwater. The formation of the second polar body after egg activation was examined ultrastructurally by both scanning and transmission electron microscopy. The second polar body was extruded from a specialized site identified by an aggregation of thick leaf‐like projections of the egg cytoplasm, a short distance from the sperm entry site about 15 min postactivation. After extrusion, formation of a cleavage furrow was completed at the base of the polar body protuberance about 30 min postactivation. The nucleus of the extruded second polar body had a nuclear envelope. The formation of the second polar body in activated eggs are discussed.

Fertilization Cone of Carp Eggs as Revealed by Scanning Electron Microscopy: fertilization cone/carp egg/scanning electron microscopy).

The process of formation of the fertilization cone in carp eggs was examined by scanning electron microscopy. The fertilized eggs responded to penetration of one sperm by primary and secondary steps of formation of a fertilization cone of unique morphology. In the primary step, the earliest fertilization cone was seen at the superior or anterosuperior part of a fused sperm head in inseminated eggs fixed 20 sec after immersion in fresh water. The cone reached a maximum of more than 10 μm in length and 3-4 μm in thickness by 40 sec, resulting in a transient plugging of the micropylar canal. In the secondary step, usually seen at 105-120 sec, a conformation reminiscent of a very small caldera volcano was formed, with the shortened earlier cone and part of the sperm tail at its top. By 2.5 min, the fertilization cone had become conical, and the sperm tail still extended from its top. At 3 min, the sperm tail was often not detectable, but a cytoplasmic eminence was still seen as a trace of the fertilization cone. The role of the earlier fertilization cone in blocking polyspermy is discussed.

Vitreous Humor Chemistry in Deaths Associated with Rapid Chilling and Prolonged Freshwater Immersion

Vitreous humor chemistry studies were performed on 13 air crash victims who had remained immersed in near-freezing fresh water for seven to eight days. Glucose concentrations were observed to be higher than those in a comparison group of autopsied cases with prolonged postmortem intervals, suggesting that rapid chilling inhibited glycolysis. Evidence of dilution of vitreous humor electrolytes was also noted. After correction for the apparent degree of dilution, the potassium concentrations were found to fall within a narrow range.