Effect Of Hydration State Research Articles

Identifying anthropogenic uranium compounds using soft X-ray near-edge absorption spectroscopy

Uranium ores mined for industrial use are typically acid-leached to produce yellowcake and then converted into uranium halides for enrichment and purification. These anthropogenic chemical forms of uranium are distinct from their mineral counterparts. The purpose of this study is to use soft X-ray absorption spectroscopy to characterize several common anthropogenic uranium compounds important to the nuclear fuel cycle. Chemical analyses of these compounds are important for process and environmental monitoring. X-ray absorption techniques have several advantages in this regard, including element-specificity, chemical sensitivity, and high spectral resolution. Oxygen K-edge spectra were collected for uranyl nitrate, uranyl fluoride, and uranyl chloride, and fluorine K-edge spectra were collected for uranyl fluoride and uranium tetrafluoride. Interpretation of the data is aided by comparisons to calculated spectra. The effect of hydration state on the sample, a potential complication in interpreting oxygen K-edge spectra, is discussed. These compounds have unique spectral signatures that can be used to identify unknown samples.

Effects of the Hydration State on the Mid-Infrared Spectra of Urea and Creatinine in Relation to Urine Analyses.

When analyzing solutes by Fourier transform infrared (FT-IR) spectroscopy in attenuated total reflection (ATR) mode, drying of samples onto the ATR crystal surface can greatly increase solute band intensities and, therefore, aid detection of minor components. However, analysis of such spectra is complicated by the existence of alternative partial hydration states of some substances that can significantly alter their infrared signatures. This is illustrated here with urea, which is a dominant component of urine. The effects of hydration state on its infrared spectrum were investigated both by incubation in atmospheres of fixed relative humidities and by recording serial spectra during the drying process. Significant changes of absorption band positions and shapes were observed. Decomposition of the CN antisymmetric stretching (νas) band in all states was possible with four components whose relative intensities varied with hydration state. These correspond to the solution (1468 cm–1) and dry (1464 cm–1) states and two intermediate (1454 cm–1 and 1443 cm–1) forms that arise from specific urea–water and/or urea–urea interactions. Such intermediate forms of other compounds can also be formed, as demonstrated here with creatinine. Recognition of these states and their accommodation in analyses of materials such as dried urine allows more precise decomposition of spectra so that weaker bands of diagnostic interest can be more accurately defined.

Microwave Response of Conducting NaxCoO2·yH2O Nanoparticles

The broadband dielectric spectroscopy has been applied to nanoplatelets of NaxCoO2·yH2O. Permittivity and conductivity have been measured on a wide frequency range from a few hertz to microwaves. The effect of hydration state and aging (drying and rehydration cycles) on the electrical properties of the NaxCoO2 nanoplatelets is well evidenced. While the sample dehydrated under vacuum (NaxCoO2·0.25H2O) shows a metallic behavior, it becomes a semiconductor with a thermally activated conduction upon rehydration (NaxCoO2·0.5H2O). The fully hydrated material (NaxCoO2·0.7H2O) obtained after synthesis and mild drying at 393 K evidences two sharp and intense conductivity and permittivity resonances above room temperature in the microwave region. We associate these two resonances with charge density waves coupling electronic transport and ionic polarizations associated with the presence of structural water in the NaxCoO2 interlayers.

Effect of Hydration State and Storage Media on Corneal Biomechanical Response From In Vitro Inflation Tests

To evaluate corneal deformation with varying intraocular pressure and the dependency of the biomechanical response on the corneal hydration state, modulated by the storage solutions or postmortem period. Thirty fresh enucleated porcine eyes were used for in vitro whole eye globe inflation experiments. The eyes were separated into five groups and treated with different solutions: 20% dextran, 8% dextran, 0.125% riboflavin-20% dextran, Optisol-GS (Bausch & Lomb, Rochester, NY), and one control group of virgin (untreated) eyes. Intraocular pressure was increased (from 15 to 55 mm Hg) and decreased (to 15 mm Hg) in 5-mm Hg steps and Scheimpflug images were taken at each step. Measurements were repeated after 24 hours. Thickness and curvature changes were analyzed as a function of intraocular pressure. Corneal deformation differed across conditions and hydration states. Dehydration by any dextran solution increased the hysteresis after the inflation/deflation cycle (14.29 vs 22.07 to 41.75 μm), whereas overnight hydration did not lead to a significant difference. Compared to control corneas, corneas treated with Optisol-GS showed the most similar behavior. Corneas treated with 0.125% riboflavin-20% dextran deformed most (Δthickness(max) = 38.27 μm), indicating a softening of the corneal tissue compared to control corneas (23.18 μm) and corneas treated with 8% dextran (21.01 μm) and 20% dextran (29.07 μm). Dextran instillation decreased corneal thickness on average to 56.5% at 0 hours and 72.7% at 24 hours. Corneal hydration and tissue preservation changed corneal biomechanics, in particular its relaxation over a period of 24 hours.

The effect of hydration state and energy balance on innate immunity of a desert reptile

IntroductionImmune function is a vital physiological process that is often suppressed during times of resource scarcity due to investments in other physiological systems. While energy is the typical currency that has been examined in such trade-offs, limitations of other resources may similarly lead to trade-offs that affect immune function. Specifically, water is a critical resource with profound implications for organismal ecology, yet its availability can fluctuate at local, regional, and even global levels. Despite this, the effect of osmotic state on immune function has received little attention.ResultsUsing agglutination and lysis assays as measures of an organism’s plasma concentration of natural antibodies and capacity for foreign cell destruction, respectively, we tested the independent effects of osmotic state, digestive state, and energy balance on innate immune function in free-ranging and laboratory populations of the Gila monster, Heloderma suspectum. This desert-dwelling lizard experiences dehydration and energy resource fluctuations on a seasonal basis. Dehydration was expected to decrease innate immune function, yet we found that dehydration increased lysis and agglutination abilities in both lab and field studies, a relationship that was not simply an effect of an increased concentration of immune molecules. Laboratory-based differences in digestive state were not associated with lysis or agglutination metrics, although in our field population, a loss of fat stores was correlated with an increase in lysis.ConclusionsDepending on the life history of an organism, osmotic state may have a greater influence on immune function than energy availability. Thus, consideration of osmotic state as a factor influencing immune function will likely improve our understanding of ecoimmunology and the disease dynamics of a wide range of species.

Elastic anisotropy of uniaxial mineralized collagen fibers measured using two-directional indentation. Effects of hydration state and indentation depth

Mineralized turkey leg tendon (MTLT) is an attractive model of mineralized collagen fibers, which are also present in bone. Its longitudinal structure is advantageous for the relative simplicity in modeling, yet its anisotropic elastic properties remain unknown. The aim of this study was to quantify the extent of elastic anisotropy of mineralized collagen fibers by using nano- and microindentation to probe a number on MTLT samples in two orthogonal directions. The large dataset allowed the quantification of the extent of anisotropy, depending on the final indentation depth and on the hydration state of the sample.Anisotropy was observed to increase with the sample re-hydration process. Artifacts of indentation in a transverse direction to the main axis of the mineralized tendons in re-hydrated condition were observed. The indentation size effect, that is, the increase of the measured elastic properties with decreasing sampling volume, reported previously on variety of materials, was also observed in MTLT. Indentation work was quantified for both directions of indentation in dried and re-hydrated conditions.As hypothesized, MTLT showed a higher extent of anisotropy compared to cortical and trabecular bone, presumably due to the alignment of mineralized collagen fibers in this tissue.

Effects of Hydration State and Resistance Exercise on Markers of Muscle Damage

It is well established that resistance exercise can damage muscle tissue, but the combined effects of hypohydration and resistance exercise on muscle damage are unclear. Two common circulating markers of muscle damage, myoglobin (Mb) and creatine kinase (CK) may be attenuated by fluid ingestion post-exercise. The purpose of this study was to examine the combined effect of resistance exercise and hydration state on muscle damage. Seven healthy resistance-trained males (age = 23 +/- 4 years; body mass = 87.8 +/- 6.8 kg; body fat = 11.5 +/- 5.2%) completed 3 identical resistance exercise bouts (6 sets of up to 10 repetitions of the back squat) in different hydration states: euhydrated (HY0), hypohydrated approximately 2.5% body mass (HY2.5), and hypohydrated approximately 5.0% body mass (HY5). Subjects achieved desired hydration states via controlled water deprivation, exercise-heat stress, and fluid intake. Both Mb and CK were measured during euhydrated rest (PRE). Mb was also measured immediately post-exercise, 1 hour (+1H) and 2 hours (+2H) post-exercise; CK was measured at 24 and 48 hours post-exercise. Body mass decreased 0.2 +/- 0.4%, 2.4 +/- 0.4%, and 4.8 +/- 0.4% during HY0, HY2.5, and HY5, respectively. Mb concentrations increased significantly (effect size >or=1, p < 0.05) from PRE (2.6 +/- 1.1, 3.5 +/- 2.8, and 3.2 +/- 1.6 nmol x L(-1)) to +1H (5.3 +/- 3.4, 6.8 +/- 3.2, and 7.6 +/- 2.8 nmol x L(-1)), and +2H (5.5 +/- 3.8, 6.2 +/- 3.0, and 7.2 +/- 3.0 nmol x L(-1)) for HY0, HY2.5, and HY5, respectively, but were not significantly different between trials. CK concentrations remained within the normal resting range at all time points. Thus, hypohydration did not enhance muscle damage following the resistance exercise challenge. Despite these results, athletes are encouraged to commence exercise in a euhydrated state to maximize endogenous hormonal, mechanical, and metabolic benefits.

Effect of Hydration State on Strength, Power, and Resistance Exercise Performance

Effect of Hydration State on Strength, Power, and Resistance Exercise Performance

The Effects of Hydration State and Resistance Exercise on Markers of Muscle Damage

PURPOSE: It is well established that resistance exercise can damage muscle tissue. Two common circulating markers of muscle damage, myoglobin (Mb) and creatine kinase (CK) may be attenuated by fluid ingestion post-exercise. The purpose of this study was to examine the combined effect of resistance exercise and hydration state on muscle damage. METHODS: Seven healthy resistance-trained males (age = 23±4 y, body mass = 87.8±6.8 kg, body fat = 11.5±5.2%) completed three identical resistance exercise bouts, six sets of up to ten repetitions of the back squat, in different hydration states: euhydrated (HY0), hypohydrated by ∼2.5% body mass (HY2.5), and hypohydrated ∼5.0% body mass (HY5). Subjects achieved desired hydration states via controlled water deprivation, exercise-heat stress, and fluid intake. Both Mb and CK were measured during euhydrated rest (PRE). Mb was also measured immediately post-exercise, one hour (+1H) and two hours (+2H) post-exercise; CK at 24 h, and 48 h post-exercise. RESULTS: Body mass decreased 0.2±0.4%, 2.4±0.4%, and 4.8±0.4% during HY0, HY2.5, and HY5, respectively. Mb concentrations increased significantly (p<0.05) PRE(44.7±19.0, 60.9±48.9, and 55.2±27.9 ng-ml-1) to+1H (93.5±59.3, 118.7±55.4, and 133.7±48.7 ng-ml-1), and+2H (97.1±67.2, 108.5±52.9, and 126.9±51.9 ng-ml-1) for HY0, HY2.5, and HY5, respectively, but were not significantly different between trials. CK concentrations remained within the normal resting range at all time points. CONCLUSION: These results indicate that hypohydration did not alter the resultant muscle damage following the resistance exercise challenge.

Mid-infrared emission spectroscopy of sulfate and sulfate-bearing minerals

Mid-infrared thermal emission spectra were acquired and are presented for 37 different sulfate minerals representing Strunz classes 6/A-D as well as a few other miscellaneous sulfate-bearing minerals (Strunz class 3/C and 8/J). Sulfate vibrational modes are assigned to each spectrum; also assigned are the modes of component OH, H 2 O, and carbonate where applicable. A discussion also is presented regarding the effect of hydration state on the emissivity spectra; dehydration of the Ca-sulfate mineral series (e.g., gypsum-bassanite-anhydrite), as well as the Mg-sulfate series, causes the high-frequency edge of the sulfate ν 3 band to shift to a larger wavenumber.

Effect of Hydration State on Testosterone and Cortisol Responses to Training-Intensity Exercise in Collegiate Runners

Exercise intensity powerfully influences testosterone, cortisol, and testosterone : cortisol ratio (T:C) responses to endurance exercise. Hydration state may also modulate these hormones, and therefore may alter the anabolic/catabolic balance in response to endurance exercise and training. This study examined the effect of running intensity on testosterone, cortisol, and T : C when exercise was initiated in a hypohydrated state. Nine male collegiate runners (age = 20 +/- 0 y, height = 178 +/- 2 cm, mass = 67.0 +/- 1.8 kg, body fat % = 9.8 +/- 0.7 %, V.O2max = 65.7 +/- 1.1 ml.kg (-1).min (-1)) completed four 10-min treadmill runs differing in pre-exercise hydration status (euhydrated, or hypohydrated by 5 % of body mass) and exercise intensity (70 % or 85 % V.O2max). Body mass, urine osmolality, and urine-specific gravity documented fluid balance; blood samples drawn pre-, immediately post-, and 20 min post-exercise were analyzed for testosterone, cortisol, and T : C. Except for heart rate measured during the 70 % V.O2max trials, heart rate, V.O2, and plasma lactate were similar between euhydrated and hypohydrated conditions for a given intensity, suggesting hypohydration did not measurably increase the physiological stress of the exercise bouts. Furthermore, hydration state had no measurable effect on testosterone concentrations before, during, or after exercise at either intensity. Regardless of exercise intensity, cortisol concentrations were greater during hypohydration than euhydration pre-exercise and 20 min post-exercise. Additionally, T : C was significantly lower 20 min post-exercise at 70 % V.O2max when subjects were initially hypohydrated (T : C = 0.055) versus euhydrated (T : C = 0.072). These findings suggest that depending on exercise intensity, T : C may be altered by hydration state, therefore influencing the balance between anabolism and catabolism in response to running exercise performed at typical training intensities.

Effects of hydration state on the synthesis and secretion of triacylglycerol by isolated rat hepatocytes. Implications for the actions of insulin and glucagon on hepatic secretion.

The effects of hepatocyte volume on the secretion of triacylglycerol were studied in order to test the suggestion that increases in the portal concentrations of osmolyte amino acids and metal ions during the prandial/early-absorptive phase may be involved in mediating the acute changes in glycerolipid metabolism observed in vivo [Zammit (1995) Biochem Soc. Trans. 23, 506-511]. Incubation of isolated rat hepatocytes with hypo-osmotic medium or in the presence of glutamine (in the presence or absence of leucine), conditions which gave an increase in cell water content of between 8 and 27%, resulted in a decrease in the rate of [14C]triacylglycerol (TAG) secretion when [14C]palmitate was used as substrate. The inhibition was proportional to the increase in cell water content. At low exogenous palmitate concentration (0.05 mM), the inhibition of [14C]TAG secretion was accompanied by a marked shift in the incorporation of label from TAG to phospholipid. In the presence of 0.5 mM palmitate this effect was attenuated, and in the presence of 1 mM palmitate it was abolished. Increased cell volume associated with incubation of hepatocytes with glutamine (in the presence or absence of leucine) also resulted in a decrease in the fraction of newly labelled TAG that was secreted into the medium. Decreased cell volume, achieved by incubation of hepatocytes with hyperosmotic medium (sufficient to decrease cell water content by approx. 9%) decreased overall [14C]TAG secretion, but did not affect the amount of label that was incorporated into phospholipid as a fraction of that incorporated into total glycerolipids. Cell shrinkage, however, diminished the fraction of newly labelled [14C]TAG that was secreted. When intracellular TAG was prelabelled with [3H]glycerol, it was found that cell shrinkage markedly inhibited (preformed) [3H]TAG secretion, whereas cell swelling did not affect this route of TAG secretion. The data are discussed in terms of the possible action of changes in cell hydration at the different loci at which hepatocyte TAG secretion is controlled, with reference to previous observations that both insulin and glucagon are able to inhibit TAG secretion in cultured rat hepatocytes and HepG2 cells.

MRI anatomy of the rat kidney at 1.5 T in different states of hydration.

The objective of this study was to determine correlation between structural anatomy and surface coil spin-echo MR imaging of the rat kidney and the effect of hydration state on MR signal intensities of the cortex and medulla. Twelve rats were studied in a pilot study with a 3-inch surface coil in a 1.5 T magnet under five different states of hydration. Serum and urine osmolality measurements were obtained immediately prior to each scan. Signal intensity measurements were made from both T1- and T2-weighted images of the cortex and medulla of both kidneys in each state of hydration. Gross and histological anatomy of the rat kidneys was correlated with the MR images. Four distinct layers were detected in vivo on MRI images of the rat kidney; these correlated with the histological layers. T1-weighted cortico-medullary differentiation was most pronounced at 48 h dehydration; T2 cortico-medullary differentiation was greatest at 72 h of dehydration. We concluded that different parts of the mammalian nephron can be identified by MR imaging and that cortico-medullary differentiation is affected by the hydration state of the animal.

Effects of hydration state on exercise thermoregulation in goats.

In this study we asked how exercise affects sweating and panting and how dehydration affects exercise thermoregulation in goats. Six goats exercised (4.8 km/h, +10% slope) for 45 min at an ambient temperature of 35 degrees C when hydrated and after 48 h without drinking water. Hematocrit (Hct), plasma protein concentration (PP), and plasma osmolality were elevated by dehydration (P less than or equal to 0.05). Hct and plasma osmolality increased further during exercise in hydrated and dehydrated animals (P less than or equal to 0.05), but PP rose only in hydrated goats (P less than or equal to 0.05). The increase in central blood temperature (Tbl) during exercise was greater in dehydrated than in hydrated animals (P less than or equal to 0.001). Evaporation by panting (Eresp) and sweating were linearly related to Tbl during exercise. The relationship between Eresp and Tbl was not affected by dehydration, but dehydrated animals showed an increased Tbl threshold for sweating. We postulate that the elevation in threshold for sweating may be due primarily to increased body fluid osmolality, and that hypovolemia may not play a significant role in the thermoregulatory adjustments to exercise in dehydrated goats.

Effect of hydration state on cardiac function in patients on chronic haemodialysis.

Haemodynamic studies were performed at rest and during exercise in five chronic haemodialysis patients at two different states of hydration, called "normal hydration" and "over-hydration" (mean change in body weight 2.9 kg). Apart from an increase in mean aortic pressure and cardiac index there were no signs of cardiac dysfunction at rest at normal hydration. On exercise the mean pulmonary artery and wedge pressure increased significantly while cardiac output doubled. Overhydration caused considerable increases in right and left sided heart pressures at rest, without any increase in cardiac index. These changes became more pronounced during exercise. Anaemia and arteriovenous shunting make dialysis patients very sensitive to volume load. Extreme anaemia should be avoided, and keeping dialysis patients in a state of low volume load should be given high priority.