Rapid Water Absorption Research Articles

Determination of hydration properties and thermal behavior of Paecilomyces variotii by differential scanning calorimetry.

Due to the structure and the composition of Paecilomyces variotii, the mycelia of this fungus could have potential applications as ingredients in wettable foods. For this use, drying could be employed, justifying the study of thermal behavior of P. variotii. The objectives of this work were to perform a study of thermal behavior of P. variotii isolates, to evaluate the hydration properties of these mycelia and to analyze the effect of different technological parameters on the latter properties. Wet cultures exhibited a wide endothermic transition, with mean values of peak temperature of 61 degrees C and denaturation enthalpy of4 J/g dry matter. Initial (50 degrees C) and final (80 degrees C) temperatures of the endothermic transition were used to dry the mycelia. Freeze-drying was also assayed. For all dried mycelia, a decrease in denaturation enthalpy between 40 and 50% was observed for drying at 50 degrees C and freeze-drying, and a drastic decrease of almost 100% for drying at 80 degrees C. According to the hydration properties, wet mycelia exhibited water holding capacity (WHC) value of 45 g water/g dry matter. Significant differences among dried mycelia, resulting WHC values in order: 50 degrees C > freeze-dried > 80 degrees C (p < 0.05) were revealed for each P. variotii strain. Fungi obtained by drying at 50 degrees C and by freeze-drying, showed a rapid water absorption (t(1/2) < 0.1 min). Ionic strength, pH and particle size of dried mycelia influenced the hydration properties.

Compressive strength, water absorption, sorptivity, abrasion resistance and permeability of self-compacting concrete containing coal bottom ash

An experimental program was carried out to study the properties of self-compacting concrete (SCC) made with coal bottom ash. The mixes were prepared with three percentages (0, 10, 20 and 30) of coal bottom ash as partial replacement of fine aggregates. Properties investigated were; slump flow, J-ring, V-funnel, L-box and U-box, compressive strength, abrasion resistance, rapid chloride permeability, water absorption, and sorptivity. Tests for compressive strength, abrasion resistance, chloride permeability were conducted up to the age of 365days whereas water absorption and sorptivity tests were conducted up to the age of 28days.Test results indicated that SCC mixes developed 28-day compressive strength between 25.8 and 35.2MPa. SCC mixes made with bottom ash exhibited very low chloride permeability resistance (between 381 and 800C) at the age of 90 and 365days respectively. Abrasion resistance, water absorption and sorptivity of SCC mixes increased with the increase in bottom ash content at a particular age, however, it decreased with increase in age.

Electrochemical impedance behavior and transport properties of silica fume contained concrete

The research study presented herein evaluates electrochemical impedance behavior and transport properties of silica fume contained concretes. The correlation between electrochemical parameters and transport properties is also studied. The test results revealed considerable improvements in transport properties, electrochemical responses and corrosion rate of the studied mixtures when silica fume was used as a supplementary cementitious material and/or w/cm was decreased. The improvements due to inclusion of silica fume were lower than those related to decrease in w/cm. Electrolyte resistance, polarization resistance, and resistance to charge transfer showed their highest correlations with rapid chloride permeability, water absorption and water permeability, respectively.

Polycaprolactone coating with varying thicknesses for controlled corrosion of magnesium

Controlled corrosion of magnesium is critical for its clinical application to orthopedic devices. For this purpose, we coated the surface of Mg with a biodegradable polymer, polycaprolactone (PCL) and attempted to control the Mg corrosion with varied coating thicknesses in a reproducible manner. As we increased the coating thickness from 0 to 13.31 ± 0.36 μm, the volume of hydrogen gas and amount of Mg ions, the indicators of Mg corrosion, decreased by almost half from 0.57 mL/cm2/day and 0.55 mg/day to 0.20 mL/cm2/day and 0.26 mg/day, respectively. However, the elemental compositions on the surface revealed possible detachment of polymer coating and rapid water absorption at the early stage of corrosion for all coating thicknesses. Therefore, the lessons learned from this study suggest pre-treatment of the Mg surface for better polymer–metal adhesion, as well as preparation of the coating with lowered porosity as a stronger water-permeation barrier, to eventually allow precise control on Mg corrosion.

Superabsorbent alginate aerogels

Polysaccharides are biopolymers that have excellent biocompatibility and biodegradability and have been considered for a wide range of pharmaceutical and biomedical applications. In this work polysaccharide-based superabsorbent aerogels are prepared using a combination of sol-gel and supercritical fluid technology. The advantages of supercritical drying are the reduced gel shrinkage, higher porosity, and three-dimensional network of the aerogel morphology compared to the morphology obtained with conventional air or vacuum drying methods. The aerogel open-porous structure and high surface area promotes rapid water absorption into the aerogel matrix by capillary force. Aerogel structural properties are modified by using different cross-linking ions and different alginate molecular weights and the influence of the aerogel properties on water absorption capacity is presented. Scanning electron microscopy is used to characterize the aerogel surface morphology, and nitrogen adsorption/desorption measurements are used to obtain information on the aerogel surface area, pore size, and pore volume. A unique feature of alginate aerogels is that they absorb more saline compared to distilled water, which is opposite to the behavior of regular superabsorbents. A gram of alginate aerogel absorbs as much as 120g of saline (0.9wt% aq. NaCl solution) solution compared to 20g of distilled water. The results from these analytical methods highlight the improved product characteristics of the aerogels synthesized using sol–gel processing technology combined with supercritical fluid technology.

Early stage hydration mechanism of cellulose ether modified thin layer cement pastes

The early stage hydration mechanism of cellulose ether modified thin layer cement pastes was studied, using brick as the matrix. Samples of 6 h, 24 h, and 3 d and 7 d hydration time were analyzed to study the hydration law on the surface of high water-absorbing matrix. Hydration products were qualitatively and semi-quantitatively analyzed using XRD, TG-DSC-DTG, FTIR and SEM. The experimental results show that there is no enough water for 2 mm thick cement pastes to hydrate, because of rapid water absorption of matrix. Trace amounts of Ca (OH)2 was detected after three days hydration. With the prolongation of hydration time, the category and concentration of hydration products do not change. Compared with 2 mm thick cement pastes, 6 mm thick cement pastes and 10 mm thick cement pastes have lower dehydration rate and water loss. The humidity field of the cement paste show different changes within the same time. 6 mm thick cement paste and 10 mm thick cement pastes have longer time and more water to hydrate. Ca(OH)2 and ettringite were detected after 6 hours hydration and the concentrations of hydration products increased from 24 hours to 7 days.

Chemosensory function of amphibian skin: integrating epithelial transport, capillary blood flow and behaviour

Terrestrial anuran amphibians absorb water across specialized regions of skin on the posterioventral region of their bodies. Rapid water absorption is mediated by the insertion of aquaporins into the apical membrane of the outermost cell layer. Water moves out of the epithelium via aquaglyceroporins in the basolateral membrane and into the circulation in conjunction with increased capillary blood flow to the skin and aquaporins in the capillary endothelial cells. These physiological responses are activated by intrinsic stimuli relating to the animals' hydration status and extrinsic stimuli relating to the detection of osmotically available water. The integration of these processes has been studied using behavioural observations in conjunction with neurophysiological recordings and studies of epithelial transport. These studies have identified plasma volume and urinary bladder stores as intrinsic stimuli that activate the formation of angiotensin II (AII) to stimulate water absorption behaviour. The coordinated increase in water permeability and capillary blood flow appears to be mediated primarily by sympathetic stimulation of beta adrenergic receptors, although the neurohypopyseal hormone arginine vasotocin (AVT) may also play a role. Extrinsic stimuli relate primarily to the ionic and osmotic properties of hydration sources. Toads avoid NaCl solutions that have been shown to be harmful in acute exposure, approx. 200-250 mm. The avoidance is partially attenuated by amiloride raising the hypothesis that the mechanism for salt detection by toads resembles that for salt taste in mammals that take in water by mouth. In this model, depolarization of the basolateral membrane of taste cells is coupled to afferent neural stimulation. In toad skin we have identified innervation of skin epithelial cells by branches of spinal nerves and measured neural responses to NaCl solutions that elicit behavioural avoidance. These same concentrations produce depolarization of the basolateral membrane in isolated epithelial preparations. As with salt taste in mammals, the neural responses and depolarization of basolateral membrane potential are partially inhibited by amiloride. In addition, toads are more tolerant of sodium gluconate solution which is consistent with the phenomenon in mammalian taste physiology termed the anion paradox in which sodium salts with larger molecular weight anions produce a reduced intensity of salt taste. Finally, toads also avoid concentrated solutions of a non-electrolyte, mannitol, which differs from NaCl solutions in not affecting transepithelial conductance and requires a longer time to depolarize the basolateral membrane. Osmotic stimuli may mediate sensory processes for longer term detection of conditions with low water potential while ionic stimuli are more important for shorter term analysis of rehydration sources.

Influence of aggregate size on the mechanical and transport properties of concretes and concrete-equivalent mortars

In this study, the influence of the aggregate size on the mechanical and transport properties of concrete and concrete-equivalent mortars is investigated. A concrete mixture was proportioned having a water–cement ratio of 0.45 and a cement content of 450 kg/m3 with a maximum aggregate size of 22.4 mm. Then, keeping the total aggregate surface area constant, three mixtures were proportioned with the same water–cement ratio, but the maximum aggregate size decreased to 16, 8, and 4 mm using the concrete-equivalent mortar method. Mechanical properties including compressive strength, splitting tensile strength and transport properties including rapid chloride permeability, water sorptivity, water absorption, and water permeability tests were performed at 7 and 28 d. Test results revealed that decreasing the maximum aggregate size increased the water permeability, rapid chloride permeability, water absorption, and sorptivity values, but decreased the compressive and split tensile strengths of concrete and concrete-equivalent mortars.

The water-absorption region of ventral skin of several semiterrestrial and aquatic anuran amphibians identified by aquaporins

Regions of specialization for water absorption across the skin of Bufonid and Ranid anurans were identified by immunohistochemistry and Western blot analysis, using antibodies raised against arginine vasotocin (AVT)-stimulated aquaporins (AQPs) that are specific to absorbing regions of Hyla japonica. In Bufo marinus, labeling for Hyla urinary bladder-type AQP (AQP-h2), which is also localized in the urinary bladder, occurred in the ventral surface of the hindlimb, pelvic, and pectoral regions. AQP-h2 was not detected in any skin regions of Rana catesbeiana, Rana japonica, or Rana nigromaculata. Hyla ventral skin-type AQP (AQP-h3), which is found in the ventral skin but not the bladder of H. japonica, was localized in the hindlimb, pelvic, and pectoral skins of Bufo marinus, in addition to AQP-h2. AQP-h3 was also localized in ventral skin of the hindlimb of all three Rana species and also in the pelvic region of R. catesbiana. Messenger RNA for AQP-x3, a homolog of AQP-h3, could be identified by RT-PCR from the hindlimb, pectoral, and pelvic regions of the ventral skin of Xenopus laevis, although AVT had no effect on water permeability. In contrast, 10(-8) M AVT-stimulated water permeability and translocation of AQP-h2 and AQP-h3 into the apical membrane of epithelial cells in regions of the skin of species where they had been localized by immunohistochemistry and Western blot analysis. Finally, water permeability of the hindlimb skin of B. marinus and all the Rana species was stimulated by hydrins 1 and 2 to a similar level as seen for AVT. The present data demonstrate species differences in the occurrence, distribution, and regulation of AQPs in regions of skin specialized for rapid water absorption that can be associated with habitat and also phylogeny.

Optimization of instant jasmine rice process and its physicochemical properties

Instant, or quick-cooking, rice is becoming more popular nowadays. However, it still poses problems with respect to rehydration time and quality. This study investigated the effects of processing factors: moisture content, pressure and drying temperature on physical and physicochemical properties of instant rice and its eating quality using response surface methodology (RSM). Hardness, chewiness and the whiteness index (WI) were used as responses due to their high R 2 (0.927, 0.633 and 0.836, respectively) and lack-of-fit. The hardness and chewiness of rice decreased as moisture content and pressure increased. Higher drying temperatures caused increases in hardness and chewiness. Only pressure and moisture content affected density, rehydration ratio, and increase in the volume of instant rice, which was due to the porosity of the kernels. Rehydration ratio had a negative correlation with density ( r = −0.886) but a positive correlation with volume increase ( r = 0.637). Pressure was the main factor influencing the pasting properties of instant rice. All pasting properties of instant rice were far lower than those of milled rice, but instant rice had higher cold paste viscosity, which is typical of pregelatinized flour. This indicated rapid water absorption and shorter cooking time. Instant rice processing also caused development of amylose–lipid complexes observed as the V-type pattern in an X-ray diffractometer.

Physicochemical properties and nutritional quality of raw cereals for newly weaned piglets

The digestibility of the starch component of raw cereals in newly weaned piglets is highly variable. Reasons for this must be elucidated if the most suitable cereals are to be used. A novel approach was employed, which consisted of assessing the physicochemical properties (rapid visco analysis, water absorption and solubility indices, particle size distribution and in vitro amylolytic digestion) of eight raw cereals contained within piglet diets and subsequently relating this in vitro data to the biological responses of weaned piglets. Trial 1 examined soft and hard wheat, trial 2 – soft wheat, barley, rye and triticale, and trial 3 – soft wheat, naked oats, whole oats and maize. The initial observation was that in vitro testing prior to animal trials is recommended in nutritional evaluation since it indicated fundamental differences between raw cereals, such as for example the levels of endogenous amylase in wheat. Starch and nitrogen digestibility differed between cereals (apparent digestibility coefficients at the 0.5 site of the small intestine ranged from 0.10 to 0.69 for starch and from 0.17 to 0.68 for nitrogen). There is also a probable relationship between the coefficients of ileal apparent starch digestibility, at approximately halfway from the gastric pylorus to the ileocaecal valve, and the presence of endogenous amylase (mean values of 0.53 and 0.62 in trials 2 and 3, respectively, for the higher amylase wheat; 0.38 for the low-amylase wheat used in trial 1). This additional variable (i.e. the unforeseen presence of endogenous amylase) in wheat made it more difficult to draw a firm conclusion about the nutritional suitability of the different cereals. All raw-cereal diets caused atrophy of the villi during the initial week following weaning, but the soft wheat was associated with the highest comparative villi height and might therefore be considered the best of all raw cereals in minimising the post-weaning growth check. For wheat, this might also suggest a possible interaction between villus architecture and endosperm texture in the immediate post-weaning period.

Behavior of Brick Samples in Aggressive Environments

The weathering of different brick samples ina range of aggressive environments has been studied.Brick samples were prepared using two clay types (fromGranada, Spain), different additives, and a range offiring temperatures (850–1100 °C). The brickscompositional and textural characteristics wereevaluated using XRD, SEM, hydric tests and mercuryintrusion porosimetry (MIP). The samples weresubjected to accelerate aging, including wet-dry,freeze-thaw and salt crystallization cycles. The decayof the bricks in polluted atmospheres was simulated ina static chamber containing sulfur dioxide (SO2)at 25 °C and 50% relative humidity. Samplesfired at 1000 °C proved to be the most durable,with better hydric behavior (fast drying and slowwater absorption) and fewer micropores. However, theywere not suitable for salt-rich environments (badperformance in the salt decay test). Samples fired at850 °C turned out to be more resistant to saltdecay, but they showed a poor hydric behavior (slowdrying and rapid water absorption) and littleresistance to freeze-thaw and wet-dry cycles. Samplesfired at 1100 °C had good hydric behavior, theyperformed well in the salt decay test, but they didnot perform as well as the samples fired at1000 °C in most accelerated aging tests. Gypsumformed on all the brick samples submitted to SO2atmosphere regardless exposure time (e.g. gypsumappears following just 24 h of exposure),composition, or firing temperature. Samples withdeposited particulate matter collected from vehicleexhausts (diesel, as well as leaded and non-leadedgasoline motor cars) resulted in the fastest gypsumdevelopment and greater abundance. On the other hand,the blank samples, and the samples withpollution-derived dust collected from historicalbuildings showed little gypsum development. Theimplications of these results in historicalbrick-building preservation in a range of aggressiveenvironments, and in polluted atmospheres inparticular, are discussed.

Aquaporins and the respiratory system: advice for a lung investigator.

Aquaporins and the respiratory system: advice for a lung investigator.

Effect of processing on water absorption and softening kinetics in chickpea (Cicer arietinumL) seeds

The processing effect on the physical properties of chickpea seeds (kabuli type cv Athenas) is reported. Soaking of chickpea seeds in different solutions (distilled water, 0·5% NaHCO3 and 0·5% CaCl2) is characterised by a rapid water absorption followed by a decrease in the hydration rate to saturation point. An improvement in chickpea softening rate and water absorption during cooking, with previous 12 h soaking in 0·5% NaHCO3, was observed. The presence of Ca2+ ions delayed the softening process in chickpea seeds. Physicochemical changes associated to the soaking and cooking process necessary for reducing cooking time are discussed. The texturometer method was estimated as a suitable objective method for the evaluation of the cooking degree in chickpea seeds. © 1998 Society of Chemical Industry

Angiotensin II suppresses water absorption through the ventral skin of Japanese tree-frogs in vitro.

We previously described two different water absorption systems in the ventral skin of the Japanese tree-frog, Hyla arborea japonica: i.e., a rapid enhanced flow, which is observed in dehydrated tree-frogs or those stimulated by adrenaline beta-agonists or vasotocin, and a slow basal flow, which is observed in normally hydrated frogs during the non-breeding season. The rapid flow is completely blocked by ouabain, which has no effects on the slow basal flow. In the present experiment, we show that the vaso-constrictive hormone angiotensin II completely inhibits basal water absorption, but has no effect on rapid water absorption. These results confirm our previous finding that the two water absorption systems in the ventral skin of the Japanese tree-frog are independent of each other.

建設材料特集 凍結融解作用を受けるコンクリートの劣化判定とその補修技術に関する基礎的研究

The deterioration caused by freeze-thaw action seems to develop gradually from the surface to the inner part. When the frost damage is limited in the cover, the weakened portion is chipped off and the recovering is made by using some repairing material. In this case, it is very important to make a perfect removal of the weakened portion, but its thickness is usually determined empirically by the chipping force and so on.In this study, experimental investigations were made on the assessing technique to the thickness of damage portion and on the performance of repairing materials to bond tightly on the concrete surface and to protect it from the frost damage.The degree of damage at different levels of depth was assessed fairly well from the mechanical degradation by applying the improved pull-off test method. The rebound number and depth of pin penetration could be also used as its measure. The rapid air permeability and water absorption tests were useful for getting the information on the changes of air and water tightness caused by the deterioration due to freeze-thaw action.By using two kinds of repairing material in nine different repairing procedures, the performance after repair was examined to evaluate the refraining effect from suffering the subsequent damage. Furthermore, four types of surface coating material were examined and their ability to prevent the freeze-thaw damage was experimentally confirmed.

Dewatering of biological slurry by using water‐absorbent polymer gel

A new concentrating/dewatering process utilizing water-absorbent polymer gels as dewatering media for biological slurries is proposed. The polymer gel applied to the process should be of porous structure for rapid water-absorption and of larger size for easier separation of gel from slurry. Poly(vinylmethylether) gel (PVMEG) prepared by gamma-ray irradiation was found to be suitable for the purpose. PVMEG swelled or shrunk reversibly in response to temperature and its transition temperature was 310K. Slurries of different properties were dewatered quite well by applying PVMEG. The water-absorbability of the gel was unaffected by the properties of organic substances contained in the slurries. An engineering calculation of the proposed dewatering process, which was called "gel dewatering process," revealed that the process was promising for concentrating/dewatering microbe-rich slurries in the respect that it would be composed of compact and simple apparatuses and be an energy saving system.

Effect of galactose on auxin-induced cell elongation in oat coleoptile segments in mannitol solutions

Oat coleoptile segments were treated with or without 10 mM galactose in the presence or absence of 10 μM IAA and various concentrations of mannitol (pre-incubation). Auxin-induced growth was inhibited by galactose. Segments were then transferred to buffer solutions containing or not containing 10 mM galactose (post-incubation). Expansion growth due to rapid water absorption was observed. The expansion growth during the post-incubation was inhibited by galactose when galactose was applied during the post-incubation period or all through the pre- and post-incubation but was not affected by galactose when it was applied only during the pre-incubation. This result indicates that the galactose effect on the expansion growth is due to its inhibitory action during the post-incubation period. Galactose has been reported to be a specific inhibitor for cell wall synthesis. Thus, it is suggested that the expansion growth during post-incubation requires cell wall synthesis and is not just the process of passive water absorption. The primary action of auxin does not seem to require new synthesis of polysaccharides.

Intestinal water and electrolyte flux of glucose-polymer electrolyte solutions

Carbohydrate-containing beverages, designed for consumption during physical activity, have been shown to improve endurance and performance during prolonged exercise. However, any solution consumed during exercise should allow rapid water absorption to ensure proper hydration. In this study, nine healthy volunteers were used to assess intestinal water and electrolyte flux characteristics of two carbohydrate-electrolyte solutions compared with water. One solution (GPF) contained 5.0% glucose polymers and 2.0% fructose, while the other (GPFS) contained 3.6% glucose polymers, 1.8% fructose, and 1.6% sucrose. Both solutions contained similar amounts of sodium, chloride, potassium, magnesium, and calcium (10, 10, 5, 1.2, and 3.2 mEq X l-1, respectively). Solutions were administered via a triple-lumen perfusion tube placed just distal to the ligament of Treitz in the small intestine. Polyethylene glycol (5 g X l-1) was employed as a non-absorbable marker to measure water and mineral fluxes. Results indicated that: jejunal intestinal net water absorption was similar for the GPF carbohydrate-mineral solution when compared with perfusion of plain water and replacement of a portion of the glucose-polymer with sucrose significantly slowed net water absorption when compared with perfusion of plain water. Net sodium, chloride, and potassium absorption also were not different for either of the two perfusates. These findings suggest that the water and mineral fluxes association with these solutions are not different from water alone. Therefore, the gastric emptying rate remains as the primary limiting factor in delivering water, carbohydrate, and minerals to the body.

Absorption of carbohydrate-electrolyte solutions in rat duodenojejunum. Implications for the composition of oral electrolyte solutions in man.

Commonly used oral electrolyte solutions are based on glucose, or sucrose, and 90 mM Na+. We had been disappointed with the ability of such solutions to improve Na+ absorption in patients with extensive resection of distal small bowel. Therefore, we tested the effect on net Na+ and water transport of combinations of different carbohydrates (glucose, sucrose, and glucose polymers) and NaCl in the rat duodenojejunum. Absorption was measured under steady-state conditions in unanesthetized animals which were infused with a different combination every hour for up to 5 hr. Of the various combinations, 10 mM glucose polymer (equivalent to 56 mmol of glucose as glucose oligosaccharides), or 60 mM glucose promoted net Na+ absorption from 120 mM NaCl and 20 mM KCl, but the glucose polymer infusate promoted more rapid water absorption than did the infusate containing glucose. The infusate of 10 mM glucose polymer in saline was initially hypotonic (276 mosmol/kg), but it became isotonic (298 mosmol/kg) as the glucose polymer was hydrolyzed during its passage through the duodenojejunum. In contrast, an infusate of 60 mM sucrose with 120 mM NaCl and 20 mM KCl remained hypertonic (320 mosmol/kg), and it did not promote water and Na+ absorption by the duodenojejunum. The efficacy of 10 mM glucose polymer with 120 mM NaCl should be tested in patients with short-bowel syndrome due to distal bowel resection.