Differences of skin morphology in Bos indicus,Bos taurus,and their crossbreds

Cutaneous evaporation is the main avenue by which cattle dissipate heat via the involvement of sweat glands and other skin components. The difference in skin morphology between B. indicus and B. taurus has been recognized, as well as differences in their ability to tolerate heat. The objective of this study was to compare skin morphology between B. indicus, B. taurus, and their crossbreds. Skin samples of Sahiwal (B. indicus) (n?=?10, reddish brown skin) and Holstein Friesian (HF) (B. taurus) (n?=?10, black and white skin) and crossbred of HF75% (n?=?10, black and white skin) and HF87.5 % (n?=?10, black and white skin) were biopsied for histological study, followed by measurement of skin components. The results indicated that breed significantly affected sweat gland morphology. The shape of the sweat gland, as indicated by the ratio of length/diameter, in Sahiwal was baggier in shape compared to HF (5.99 and 9.52) while values for crossbreds were intermediate (7.82, 8.45). The density and volume of sweat glands in Sahiwal (1,058 glands/cm²; 1.60 μ³?×?10^?6) were higher than in HF (920 glands/cm²; 0.51 μ³x10^?6) and crossbreds, both HF 75 % (709 glands/cm²; 0.68 μ³?×?10^?6) and HF 87.5 % (691 glands/cm²; 0.61 μ³?×?10^?6) respectively. However, capillary surface area was greater for HF (2.07 cm²) compared to Sahiwal (1.79 cm²); accordingly, the lower genetic fraction of HF in crossbred cattle showed less capillary surface area (1.83 and 1.9 cm² for HF75% and HF87.5 %) (P?<?0.01). Nerve density was not significantly different between Sahiwal and HF but was higher in the crossbred (P?<?0.01) cattle. Moreover, the effect of skin color (black and white) was evaluated and it was found that there was an interaction (P?<?0.01) between breed and skin color on the skin components. This study reveals that there are differences in skin morphology among B. indicus, B. taurus and their crossbreds, with these differences being more or less related to the genetic fraction of HF. This may imply that capability for cutaneous evaporative heat loss and tolerance to heat in crossbred cattle could be related to skin morphology.     

Attenuated thermoregulatory responses with increased plasma osmolality in obese subjects during two seasons

Obese subjects may be more vulnerable to injury from heat stress, and appear to be less efficient at thermoregulation. Sweat rate, tympanic temperature and osmolality in obese subjects were investigated in Japan during two seasons. The purpose of this study was to examine the relationship between obesity, thermoregulatory response and season. Five obese (BMI, 32.0?±?4.9 kg/m²) and five non-obese (BMI, 23.2?±?2.9 kg/m²) men participated in this experiment at latitude 35°10′ N and longitude 136°57.9′E. The average atmospheric temperature was 29.1?±?1.0 °C in summer and 3.3?±?1.4 °C in winter. Tympanic temperature and sweat rate were measured during leg water immersion at 42 °C for 30 min. Blood samples were analyzed for plasma osmolality. The relationship between tympanic temperature and sweat rate decreased significantly in obese compared to in non-obese subjects in both seasons, there being a lowered sweat rate for any core temperature in obese subjects. Plasma osmolality was significantly higher in obese than in non-obese subjects in both seasons. Thermal sensation increased significantly in non-obese than in obese in winter but not in summer. Our data show that thermoregulatory responses are attenuated in obese subjects compared with controls, suggesting that obese people are at increased risk of heat-related illnesses.     

Sensible heat transfer and thermal windows in Dasyprocta leporina (Mammalia,Rodentia)

This study aimed to evaluate the diurnal variation of the sensible heat transfer in red-rumped agoutis (Dasyprocta leporina) bred in captivity in a semi-arid environment. In addition, we seek to identify thermal windows by infrared thermography during the daytime period (07:00, 09:00, 11:00, 14:00, and 16:00). The body surface temperature was higher in the pinna (36.84 ± 0.11 °C), followed by the hind limbs (36.55 ± 0.11 °C). These body regions were primarily responsible for heat loss by radiation (which was 10.13 ± 1.17 W m^?2 and 11.19 ± 1.17 W m^?2, respectively), and acted like biological thermal windows. Heat transfer by convection was more intense in the body trunk and hind limbs at all times of the day. Thus, sensible heat transfer is important for maintaining homeothermy in red-rumped agouti in hot environments. In conclusion, these rodents use specialized body regions (pinna and hind limbs) for heat transfer.     

Daily variations in the thermoregulatory behaviors of naked neck broilers in an equatorial semi-arid environment

The aim of this study was to evaluate the daily variations in the thermoregulatory behavior of 4- to 6-week-old naked neck broilers (Label Rouge) in an equatorial semi-arid environment. A total of 220 birds were monitored for 5 days starting at 0600 hours and ending at 1800 hours. The period of observation was divided into classes of hours (C _H). The observed behaviors were as follows: feed and water intake, wing-spreading, sitting or lying, and beak-opening. A total of 14,300 behavioral data values were registered. In C _H 2 (0900 hours to 1100 hours) and 3 (1200 hours to 1500 hours), the greatest average body surface temperature was recorded (34.67?±?0.25 °C and 35.12?±?0.22 °C, respectively). The C _H had an effect on the exhibition of all behaviors with the exception of the water intake behavior. Feed intake was more frequent in C _H 1 (0600 hours to 0800 hours) and 4 (1600 hours to 1800 hours). In C _H 2 and 3, the highest frequency of sitting or lying behavior was observed. Beak-opening and wing-spreading behaviors occurred more frequently in C _H 3 where the body surface temperature (35.12?±?0.22 °C), radiant heat load (519.38?±?2.22 W m^?2), and enthalpy (82.74?±?0.36 kJ kg^?1 of dry air) reached maximum recorded averages. Thus, it can be concluded that naked neck broilers adjust their behavior in response to daily variations in the thermal environment. Wing-spreading and beak-opening behaviors are important adaptive responses to the thermal challenges posed by the equatorial semi-arid environment.     

Fan-precooling effect on heat strain while wearing protective clothing

This study compared heat strain during walking while wearing impermeable protective suits between fan-precooling and nonprecooling conditions. Six males engaged in 60 min of walking at a moderate speed (～2.5 km/h) in a hot environment (37 °C, 40 % relative humidity). Fanning using a fan (4.5 m/s) and spraying water over the body before wearing the suits produced significantly lower rectal temperature before the walking (37.3?±?0.1 °C vs. 37.0?±?0.1 °C, P?P?相似文献   

The effects of high temperature and roof modification on physiological responses of swamp buffalo (Bubalus bubalis) in the tropics

The objective of the experiments reported here was to measure the effects of cooling techniques (Modified roof vs Normal roof) on the performance and physiology of 12 young male buffaloes with a similar live weight of 160 kg. The study was conducted at Chainat Agriculture and Technology College, Chainat Province, Thailand. The animals were divided randomly into two groups, each group comprising six buffaloes, and the two groups were studied to evaluate the effects of modified roofing (normal roof fitted with woven polypropylene shade cloth) on the subjects’ physiological responses to heat stress under hot humid conditions. The modified roof resulted in lowered heat stress in buffaloes compared to those under a standard roof. The difference was shown by the buffaloes having a significantly lower mean rectal temperature (39.14?±?0.07 vs 40.00?±?0.10°C) and plasma cortisol (2.14?±?0.24 vs 3.38?±?0.37 ng/ml). The average daily water consumption was significantly lower in the MR group (MR, 29.71?±?0.86 vs NR, 34.14?±?1.06 L head ^?1 day^?1), while there was a tendency for the roughage intake to be higher in the MR group compared to that of the NR group (MR, 5.88?±?0.18 vs NR, 6.44?±?0.19 kg head-1 ^?1 day^?1; P?=?0.0508). It was concluded that roof modification facilitated a reduction in heat load from roof re-radiation, and was an effective means of alleviating thermal stress in young buffaloes.     

Development and Evaluation of a Novel Delivery System Containing Phytophospholipid Complex for Skin Aging

Citrus auranticum and Glycyrrhiza glabra are rich in anti-oxidant polyphenols helpful in prevention of skin aging. Polyphenols have high polarity and lower skin penetration resulting in lower cutaneous delivery. The present work is attempted to develop a novel polyherbal phospholipid complex cream to improve cutaneous delivery of polyphenols for sustained anti-oxidant action. Phytochemical and in vitro anti-oxidant evaluation was done on methanolic extracts of orange peel and liquorice powder. Total phenolic content, total flavonoid content, and anti-oxidant assays were done on different ratios of orange peel and liquorice extract. Ratio 1:2 gave highest total phenolic content (TPC) (530.00?±?1.56 mg gallic acid equivalent (GAE)?g^?1 extract), total flavonoid content (TFC) (246.25?±?1.03 mg rutin equivalent (RUE)?g^?1 extract), 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity (87.99?±?0.64%), and H₂O₂ scavenging activity (72.47?±?0.86%) and hence was used for formulation. Solvent evaporation method using methanol with 1:1 extract to phospholipid ratio was found to have entrapment efficiency of 93.22?±?0.26%. Evaluation parameters like scanning electron microscopy (SEM), Fourier transform infrared spectrophotometry (FT-IR), and differential scanning calorimetry (DSC) confirmed formation of complex. The complex was formulated as oil-in-water cream and evaluated for various parameters. The optimized cream containing 1% complex was non-irritant and was found to be stable for 3-month period under conditions of stability study. Ex vivo diffusion studies showed that extract phospholipid complex cream had better retention of polyphenols in the skin when compared to conventional extract cream giving prolonged and stronger topical action. The cream had an anti-elastase activity of 28.02?±?0.95% at concentration of 3000 μg ml^?1 (w/v). Thus, the developed safe and stable polyherbal phytophospholipid complex cream exhibited good potential as anti-aging cosmeceutical.     

Volume and composition of hand sweat of white and black men and women in desert walks

Many investigators have sought, but failed to find, ethnic differences in the number and regional distribution of active sweat glands. In this study measurements have been made of sweat secreted on one hand and also on the whole body of Whites and Blacks walking in desert heat. Whites numbered 31 men and 27 women, ages 30 to 88 years; there were 21 Black men and 31 Black women, ages 16 to 61 years. Each walked on three occasions for 1 hour at a rate that required an oxygen consumption of about 40% of aerobic capacity. Ambient temperature ranged from 32 to 44°C in 1979 and 1980; means were 38.4°C in 1979 and 36.7°C in 1980. There was no sweat in the gloves of many Blacks; this was true of only a few Whites. Volume of body sweat increased in both races with rate of walking; volume of hand sweat increased more in Whites than in Blacks. The Mann-Whitney test revealed that volumes of hand sweat were significantly greater for Whites than for Blacks. It was concluded that in desert walks most Whites and few Blacks sweat freely on their hands. In samples of hand sweat, Na⁺, K⁺, and Cl^? were determined. Concentrations of each ion varied widely in both races, and were unrelated to race. Concentrations of Na⁺ and Cl^? generally are somewhat higher in hand sweat than in body sweat; concentrations of K⁺ are much higher. It follows that the values for concentration of Na⁺ and Cl^? reported in Table 3 probably are somewhat higher than would have been found in body sweat, and concentrations of K⁺ are probably much higher.     

Maturation- and aging-related changes in heat loss effector function

This paper addresses the ways in which heat loss effector functions change with maturation and aging, using data obtained in our laboratory. Prepubertal children have an underdeveloped sweat function compared with young adults; this is compensated by a greater surface area-to-mass ratio and relatively greater heat loss from cutaneous vasodilation on the head and trunk when the air temperature is lower than the skin temperature. As the heat dissipation depends greatly on the evaporation of sweat, the core temperature of prepubertal children is greater than that of young adults owing to the underdevelopment of sweating. In the elderly the heat loss effector function decreases with aging. The decrease may first involve cutaneous vasodilation, then sweat output per gland, and finally active sweat gland density; and it may proceed from the lower limbs to the back of the upper body, the front of the upper body, then the upper limbs and finally to the head.     

Body temperature and respiratory dynamics in un-shaded beef cattle

In this study body temperature (BT, °C) and panting score (PS, 0–4.5; where 0?=?no panting/no stress and 4.5?=?catastrophic stress) data were obtained from 30 Angus steers housed outside over 120 days Steers were implanted with a BT transmitter on day ?31, BT was recorded at 30-min intervals to a data logger and downloaded each day to a database. The cattle were housed in ten outdoor un-shaded pens with an earthen floor, eight of which had a pen floor area of 144 m² (three transmitter steers plus five non-transmitter steers; 18 m²/steer) and two had an area of 168 m² (three transmitter steers and six non-transmitter steers; 18.7 m²/steer). Only data from the transmitter steers were used in this study. The PS of the steers was obtained daily (± 15 min) at 0600 hours (AM), 1200 hours (MD) and 1600 hours (PM). At the same times climate variables (ambient temperature, black globe temperature, solar radiation, relative humidity, wind speed and rainfall) were obtained from an on-site weather station. PS observations were made from outside the pens so as not to influence cattle responses. The two closest BT values to the time when PS was obtained were downloaded retrospectively from a logger and averaged. A total of 8,352 observations were used to generate second order polynomial response curves: (AM) y?=?39.08?+?0.009?x +?0.137x ² (R ²?=?0.94; P? y?=?39.09?+?0.914x ? 0.080x ² (R ²?=?0.89; P? y?=?39.52?+?0.790x ? 0.068x ² (R ²?=?0.83; P?x?PS. These data suggest that PS is a good indicator of body temperature. The BT at MD corresponded to slightly lower PS compared with PM, e.g., for PS 1; BT at MD?=?39.1?±?0.05 °C whereas BT at PM?=?39.5?±?0.05 °C. However during AM, BT was lower (P?相似文献   

Dry anaerobic digestion of high solids content dairy manure at high organic loading rates in psychrophilic sequence batch reactor

Cow manure with bedding is renewable organic biomass available around the year on dairy farms. Developing efficient and cost-effective psychrophilic dry anaerobic digestion (PDAD) processes could contribute to solving farm-related environmental, energy, and manure management problems in cold-climate regions. This study was to increase the organic loading rate (OLR), fed to a novel psychrophilic (20 °C) dry anaerobic digestion of 27 % total solid dairy manure (cow feces and wheat straw) in sequence batch reactor (PDAD-SBR), by 133 to 160 %. The PDAD-SBR process operated at treatment cycle length of 21 days and OLR of 7.0 and 8.0 g total chemical oxygen demand (TCOD)?kg^?1 inoculum day^?1 (5.2?±?0.1 and 5.8?±?0.0 g volatile solids (VS)?kg^?1 inoculum day^?1) for four successive cycles (84 days) produced average specific methane yields (SMYs) of 147.1?±?17.2 and 143.2?±?11.7 normalized liters (NL)?CH₄?kg^?1 VS fed, respectively. PDAD of cow feces and wheat straw is possible with VS-based inoculum-to-substrate ratio of 1.45 at OLR of 8.0 g TCOD kg^?1 inoculum day^?1. Hydrolysis was the limiting step reaction. The VS removal averaged around 57.4?±?0.5 and 60.5?±?5.7 % at OLR 7.0 and 8.0 g TCOD kg^?1 inoculum day^?1, respectively.     

Relations of Bromine,Iron, Rubidium,Strontium, and Zinc Content to Morphometric Parameters in Pediatric and Nonhyperplastic Young Adult Prostate Glands

The variation with age of the Br, Fe, Rb, Sr, and Zn mass fractions and some histological characteristics of intact prostate glands of 50 subjects aged 0–30 years was investigated by an energy-dispersive X-ray fluorescence and a quantitative morphometric analysis. Mean values?±?standard error of the mean (M?±?SΕΜ) for the mass fractions (in milligrams per kilogram wet-mass basis) of these trace elements in pre-puberty were: Br—10.5?±?1.3, Fe—28.6?±?4.1, Rb—3.05?±?0.27, Sr—0.42?±?0.08, and Zn—32.9?±?3.2. During puberty and postpuberty, when there is a significant increase in circulating androgens, the mean values were: Br—5.60?±?0.57, Fe—19.3?±?1.6, Rb—3.50?±?0.28, Sr—0.24?±?0.03, and Zn—113?±?10. Mean values (M?±?SΕΜ) of percent volumes (%) of the stroma, epithelium, and lumen in the prostate before puberty were 73.4?±?2.6, 20.4?±?1.7, and 4.45?±?0.94, respectively, versus 46.5?±?2.5, 38.5?±?1.9, and 14.9?±?1.2 during puberty and postpuberty. A significant positive correlation between the prostatic Zn and percent volume of both glandular epithelium (r?=?0.573, p?≤?0.001) and glandular lumen (r?=?0.725, p?≤?0.001) was found. For the first time, it has been demonstrated that the glandular lumen is a main pool of Zn accumulation, and that the stroma is a main pool of Br and Fe accumulation in the normal human prostate, for the age range 14 to 30 years. It was concluded that the Zn binds tightly within the prostatic fluid because the volume of glandular lumen reflects the volume of prostatic fluid.     

Radiation transfer and heat budget during the ice season in Lake Pääjärvi, Finland

Lake Pääjärvi, a boreal Finnish lake, was investigated in winter for weather conditions, structure and thickness of ice and snow, solar radiation, and under-ice current and temperature. Heat budget of Lake Pääjärvi in January–March was governed by terrestrial radiation losses of 20–35 W m^?2 recompensed by ice growth of 0.5–1.0 cm day^?1. In April, snow melted, albedo decreased from 0.8 to <0.1, and the mean ice melt rate was 1.5 cm day^?1. Internal melting and surface melting were about equal. The mean turbulent heat loss was small. The heat flux from the water to ice was about 5 W m^?2 in winter, increasing to 12 W m^?2 in the melting season. The light attenuation coefficient was 1.1 m^?1 for the congelation ice (black ice) in winter, compared with 1.5 m^?1 for the lake water, and it was up to 3 m^?1 for candled congelation ice in spring, and about 10 m^?1 for superimposed ice (white ice) and snow. Gas bubbles were the main factor that reduced the transparency of ice. The radiation penetrating the ice heated the water body causing convective currents and horizontal heat transfer. This increased the temperature of the water body to about 3°C before the ice break-up. After the snow had melted, the euphotic depth (the depth of 1% surface irradiance) was estimated as 2.0 m, only two-thirds that in summer.     

Inheritance pattern and genetic correlations among growth and wood quality traits in Para rubber tree (<Emphasis Type="Italic">Hevea brasiliensis</Emphasis>) and implications for breeding

Inheritance pattern of wood traits viz. specific gravity, fibre dimensions and fibre-derived biometrical indices and their interactions among themselves and with that of growth are reported in Hevea brasiliensis. Girth (h² =???0.02?±?0.44 to h² =?0.35?±?0.24) showed moderate genetic control. Among wood traits, specific gravity (h²?=?0.15?±?0.31 to h² =?0.33?±?0.28) was found to be under moderate genetic control. Fibre traits viz., fibre length (h² =???0.26?±?0.30 to h² =?0.50?±?0.34), fibre diameter (h² =?0.19?±?0.49 to h² =?0.70?±?0.11), fibre lumen diameter (h² =???0.18?±?0.35 to h² =?0.56?±?0.47) and fibre wall thickness (h² =???5.17?±?5.26 to h² =?0.50?±?0.50) were under moderate to strong genetic control. Among fibre-derived indices, flexibility coefficient (h² =?0.48?±?0.21 to h² =?0.89?±?0.29) showed moderate to very strong genetic control. The Runkel ratio (h² =???0.40?±?0.27 to h² =?0.42?±?0.29) and slenderness ratio (h² =???0.36?±?0.29 to h² =?0.43?±?0.28) showed moderate genetic control. Girth showed very strong positive genetic correlation with fibre wall thickness and strong positive correlation with fibre width indicating scope of indirect selection potential for these traits. Wood specific gravity was not correlated with either girth or fibre traits. Hence, it would be possible to concomitantly improve growth and fibre traits without adversely affecting wood specific gravity. Moderate to very high estimates of heritability for fibre traits, girth and specific gravity indicated that considerable genetic gain can be realised for these traits. Implications of the above findings in genetic improvement of wood in Hevea are discussed.     

Effect of whey protein isolate on rehydration after exercise

Studies have examined adding protein to carbohydrate–electrolyte rehydration drinks, but the effects of protein in isolation remain unknown. Ten subjects completed two trials in which they were dehydrated (~2 % of pre-exercise body mass) by intermittent cycling in the heat. Subjects then rehydrated (150 % total mass loss) over 1 h with mineral water (W) or mineral water plus 20 g L^?1 whey protein isolate (WP) and remained in the laboratory for a further 4 h. Blood and urine samples were provided pre-exercise, post-exercise, post-rehydration and every hour thereafter. From blood samples, serum osmolality, change in plasma volume and plasma albumin content was determined, whilst the volume and osmolality of urine samples were determined. There was no difference between trials for total urine volume [W: 1,234 (358) mL; WP: 1,306 (268) mL; P = 0.409], drink retention [W: 40 (14) %; WP: 37 (14) %; P = 0.322] or net fluid balance [W: ?605 (318) mL; WP: ?660 (274) mL; P = 0.792] 4-h post-rehydration. Plasma volume was greater 3 and 4 h post-drinking during WP, and plasma albumin content relative to pre-exercise was increased 1–4 h post-drinking in WP only. These results suggest that addition of 20 g L^?1 whey protein isolate neither enhances nor inhibits post-exercise rehydration, when a volume equivalent to 150 % of sweat losses is ingested in 1 h. As post-exercise nutritional requirements are multifactorial (rehydration, glycogen resynthesis, myofibrillar/mitochondrial protein synthesis), these data demonstrate that when post-exercise protein intake might benefit recovery or adaptation, this can be achieved without compromising rehydration.     

Blood clearance and occupational exposure for <Superscript>177</Superscript>Lu-DOTATATE compared to <Superscript>177</Superscript>Lu-PSMA radionuclide therapy

The main target of this work is to examine blood clearance and external exposure for ¹⁷⁷Lu-DOTATATE compared with new emerging ¹⁷⁷Lu-PSMA therapy. Blood clearance and radiation exposure of 31 patients treated with 5.5?±?1.1 GBq ¹⁷⁷Lu-DOTATATE were compared to those of 23 patients treated with 7.4 GBq ¹⁷⁷Lu-PSMA. Dose rates were measured at several distances and time points up to 120 h after treatment. Blood samples were collected conjunctively after infusion. Caregiver’s cumulative dose was measured by means of an OSL (optically stimulated luminescence) dosimeter for 4–5 days and medical staff’s dose was also estimated using electronic personal dosimeters. Finger dose was determined via ring TLD (Thermoluminescence Dosimeter) for radiopharmacists and nurses. Dose rates due to ¹⁷⁷Lu-DOTATATE at a distance of 1 m, 4 h and 6 h after infusion, were 3.0?±?2.8 and 2?±?1.9 µSv/(h GBq), respectively, while those due to ¹⁷⁷Lu-PSMA were 3.1?±?0.8 and 2.2?±?0.9 µSv/(h GBq). Total effective dose of 17 caregivers was 100–200 µSv for ¹⁷⁷Lu-DOTATATE therapy. Mean effective doses to nurses and radiopharmacists were 5 and 4 µSv per patient, respectively, while those for physicists and physicians were 2 µSv per patient. For ¹⁷⁷Lu-DOTATATE, effective half-life in blood and early elimination phase were 0.31?±?0.13 and 4.5?±?1 h, while they were found as 0.4?±?0.1 and 5?±?1 h, respectively, for ¹⁷⁷Lu-PSMA. The first micturition time following ¹⁷⁷Lu-DOTATATE infusion was noted after 36?±?14 min, while the second and third voiding times were after 74?±?9 and 128?±?41 min, respectively. It is concluded that blood clearance and radiation exposure for ¹⁷⁷Lu-DOTATATE are very similar to those for ¹⁷⁷Lu-PSMA, and both treatment modalities are reasonably reliable for outpatient treatment, since the mean dose rate [2.1 µSv/(h GBq)] decreased below the dose rate that allows release of the patient from the hospital (20 µSv/h) after 6 h at 1 m distance.     

Physiological and production response of dairy goats bred in a tropical climate

The aim of this work was to determine the adaptability of Saanen and ½Saanen?×?½Anglo-Nubian (½S½AN) goats bred in tropical climates. The study included 30 goats, 15 Saanen and 15 ½S½AN. The data was collected during the rainy and dry seasons. During the whole experimental period, the environment variables were recorded, as well as rectal temperature (RT), superficial temperature (ST), respiratory rate (RR) and heart rate (HR) and milk production (MP). The adaptability coefficient (AC) was calculated for both genotypes. The averages were evaluated by ANOVA at 5 % probability. There was a genotype and period of year effect, as well as the interaction genotype?×?period of year. Pearson's simple correlation analysis was then carried out between milk production and physiological and environment variables. There was a statistical difference (p?p?p?相似文献   

Transition duration of ingested deuterium oxide to eccrine sweat during exercise in the heat

The time necessary for the initial appearance of ingested water as sweat during exercise in the heat remains unknown. Based on the current literature, we estimated fluid transition through the body, from ingestion to appearance as sweat, to have a minimum time duration of approximately three minutes. The purpose of this study was to test this prediction and identify the time necessary for the initial enrichment of deuterium oxide (D₂O) in sweat following ingestion during exercise in the heat. Eight participants performed moderate intensity (40% of maximal oxygen uptake) treadmill exercise in an environmental chamber (40 °C, 40% rH) to induce active sweating. After fifteen minutes, while continuing to walk, participants consumed D₂O (0.15 ml kg⁻¹) in a final volume of 50 ml water. Scapular sweat samples were collected one minute prior to and ten minutes post-ingestion. Samples were analyzed for sweat D₂O concentration using isotope ratio mass spectrometry and compared to baseline. Mean±SD ∆ sweat D₂O concentration at minutes one and two post-ingestion were not significantly higher than baseline (0 min). Minutes three (9±3 ppm) through ten (23±11 ppm) post-ingestion had ∆ sweat D₂O concentrations significantly (P<0.05) higher than baseline. Such results suggest that ingested water rapidly transports across the mucosal membrane of the alimentary canal into the vasculature space, enters the extravascular fluid, and is actively secreted by the eccrine sweat glands onto the surface of the skin for potential evaporation in as little as three minutes during exercise in the heat.     

Inter-animal radiation as potential heat stressor in lying animals

A model for predicting inter-animal radiant heat exchange in shaded animals is presented, with emphasis on mature cattle. When a cow’s surface temperature is 35 °C, as is common in warmer climates, it loses ～510 Watt m^?2 as radiant heat. Net radiant heat balance depends on radiation coming from bodies in the vicinity. In the 30 °C radiant temperature shaded environment typical of warm climates, net radiant loss from a lactating cow is ～60 Watt m^?2, i.e., 30 % of its ～173 Watt m^?2 heat production. Cows rest for 8–14 h day^?1. The heat exchange of a lying cow differs from that of a standing one: the body center is low and 20–30 % of its surface contacts a surface of relatively low heat conductance. Lying reduces the impact of the surrounding shaded area on heat exchange but increases that of heat radiating from neighboring cows. When a cow rests adjacent to other cows, with 1.25 m between body centers when in stalls, it occupies about 140° of the horizontal plane of view. Heat emitted from the animal’s surface reduces the net radiant heat loss of a resting cow by ～30 Watt m^?2. In contrast, the presence of cows at 5 and 10 m distance, e.g., cows resting on straw in loose yard housing, reduces the net radiant heat loss of the resting cow by 9 and 5 Watt m^?2, respectively. Radiant heat input increases with animal density, which is beneficial in cooler climates, but acts as a stressor in warm climates.     

Key parameters for outdoor biomass production of Scenedesmus obliquus in solar tracked photobioreactors

The biomass productivity of Scenedesmus obliquus was investigated outdoors during all seasons in solar tracked flat panel photobioreactors (PBR) to evaluate key parameters for process optimization. CO₂ was supplied by flue gas from an attached combined block heat and power plant. Waste heat from the power plant was used to heat the culture during winter. The parameters pH, CO₂, and inorganic salt concentrations were automatically adjusted to nonlimiting levels. The optimum biomass concentration increased directly with the photosynthetic active radiation (PAR) from 3 to 5 g dry weight (DW)?L^?1 for a low PAR of 10 mol photons m^?2 day^?1 and high PAR of 40–60 mol photons m^?2 day^?1, respectively. The annual average biomass yield (photosynthetic efficiency) was 0.4?±?0.5 g DW mol^?1 photons. However, biomass yields of 1.5 g DW mol^?1 photons close to the theoretical maximum were obtained at low PAR. The productivity (including the night biomass losses) ranged during all seasons from ?5 up to 30 g DW m^?2 day^?1 with a mean productivity of 9?±?7 g DW m^?2 day^?1. Low night temperatures of the culture medium and elevated day temperatures to the species-specific optimum increased the productivity. Thus, continuous regulation of the biomass concentration and the culture temperature with regard to the fluctuating weather conditions is essential for process optimization of outdoor microalgal production systems in temperate climates.