Changes In Water Loss Research Articles

Water Loss Changes of Antirrhinum majus L. Cut Flowers as Influenced by Genotype

Cut flowers of a short(S) lived (3 days) inbred, a long(L) lived (15 days) inbred and their hybrid (F1, 7.3 days) of Antirrhinum majus L. were evaluated for water loss when held in deionized water under continuous fluorescent light at 25°C. Flowering stems for water loss evaluation were harvested when the basal five to six florets expanded. Cut stems were placed in narrowed-necked bottles with the open area between the stem and bottle sealed with Parafilm. Stem weight and water weight in the bottle were taken every 24 h. Water loss evaluation was continued until 50% of the open florets on the flowering stem wilted or turned brown. Overall, water loss from all accessions was highest 24 h postharvest, declined rapidly between 24 to 96 h, and remained unchanged throughout the remainder of postharvest life. Between 24 to 96 h, the slope of the line for water loss was greatest for L, least for S, and intermediate for the F1. It appears that longest postharvest life of A. majus is associated with the most rapid decline of water loss immediately postharvest to a level, which remains constant.

Effect of storage media on subsequent water loss and regain by human and bovine dentine and on mechanical properties of human dentine in vitro

This study was designed to determine whether storage media and time affect any changes in water loss with dehydration of dentine. The effect of storage of prepared bars was also compared with storage of whole teeth. Prepared bovine dentine bars were stored for 3 days or 12 weeks in deionized water, phosphate-buffered saline or neutral-buffered formalin and whole teeth were stored in neutral-buffered formalin for 12 weeks before the preparation of dentine bars. Specimens were removed from storage and weight loss with dehydration, determined gravimetrically, was equated directly to water loss. Tensile and three-point bend tests were made on human dentine bars that had been stored in deionized water or neutral-buffered formalin for 3 days. Results were subjected to analysis of variance and Duncan's new multiple-range test. Weight loss by evaporation from dentine at 22.3 °C and 53.2% relative humidity was rapid and non-linear, reaching 5.05 ± 0.55% for bovine dentine compared with 3.33 ± 0.63% for human dentine after 7 days. Water loss with dehydration was not affected by 3-day storage of specimens in different media or by 12-week storage of whole teeth, but was affected when prepared specimens were stored for 12 weeks. Different storage media had no significant effect ( p > 0.05) on the strength or toughness of human dentine. Water loss in human dentine was associated with shrinkage of specimens, but these dimensional changes were fully recovered with rehydration. Storage of teeth in neutral-buffered formalin followed by minimal storage time for prepared specimens is recommended to minimize changes in dentine after extraction.

Related surface and heat of immersion characterization of some alumina samples

MnCl2- and CuCl2-loaded aluminas were thermally treatedin vacuo in the temperature range 20–500 °C. The water loss, specific surface area from nitrogen adsorption measurements and the integral heat of immersion in water were determined for all the samples. The high-pressure hysteresis loop displayed in the adsorption isotherms, together with the limited increase in adsorption values near saturation indicate the dominance of mesopores in the tested samples, as also detected by theVa-t method of isotherm analysis. Changes in the slope ofVa-t plots suggests that the mesopores rather belong to narrow-ranged mesopore sizes, which are thus considered responsible for adsorption in thet-ranges of 0.5–0.7 and above 0.7 nm. The constancy ofVa(mlg−1) values abovet=1.2 nm points out the absence of effective capillary condensation in the high relative pressure region. Variations of BET-surface area and the reciprocal of average pore radius, ¯r−1 (nm−1), as functions of the heat-treatment temperature indicate that MnCl2-loaded samples display a higher thermal stability than CuCl2-loaded samples; the latter exhibit some aggregation cementation behaviour. At temperatures below 300 °C, the heat of immersion data are not as predicted from changes in water loss and surface-area parameters. Thus, MnCl2-loaded samples display lower heat of immersion values than the respective CuCl2-loaded samples, despite the higher BET areas of the former samples; an effect which may be tentatively interpreted in terms of the capability of the smaller sized Mn2+ ions to preserve more water molecules via such processes as complex formation, ion hydration and crystallization, which contribute to lowering the integral heat measured. This apparent discrepancy in the behaviour of integral heat of immersion (Jg−1) data with water loss (gg−1) at temperatures below 300°C is clarified by considering the change in the heat of immersion per unit area,hi (J m−2) with the temperature of treatment.

Influence of Storage Temperatures on Ultrastructural Changes and Water Loss of Hassaku Fruit.

The changes in water loss, membrance permeability and ultrastructure of Hassaku fruits (Citrus hassaku Hort. ex. Tanaka) were conducted in various storage temperatures. The results showed that storage temperature was an important factor affecting on the water loss, membrane permeability and the occurrence of rind-oil spot symptom. With a scanning electron microscope (SEM), the temperature also induced the ultrastructural changes of surface wax. The marked increases in membrane permeability and changes in ultrastructure of peel were observed in fruits stored at 10°C for 90 days and throughout this investigation period. Broken oil glands were observed on the peel of fruits stored at 10°C for 30 days and more notices when kept for a longer period of time. Moreover, the increases in wax were observed on the peel of fruits stored at 10°C and 20°C for a longer period of time, which were parallel to the occurrences of rind-oil spot symptom, except for the fruits stored at 0°C. The relationships among the ultrastructural changes of peel, membrane permeability and the occurrences of rind-oil spot symptom are discussed.

Related surface and heat of immersion characterization of some alumina samples I: Rhône poulenc activated alumina

Activated alumina was thermally dehydrated in vacuo at different temperatures in the range 20 – 500 °C. Nitrogen adsorption measurements, heats of immersion in water, methanol and carbon tetrachloride, and water losses (in grams of water per 100 g of the sample) of the different heat-treated samples were estimated and correlated. Nitrogen adsorption measurements show the occurrence of type II adsorption isotherms which are characterized by hysteresis phenomena. The area of the hydteresis loop increases up to 200 °C; thereafter, it decreases with further increase temperature until 500 °C is reached. An initial increase in the area of the hysteresis loop (below 200 °C) is interpreted on the basis of the increased physisorbed water loss up to 200 °C. The decreased area of the hysteresis loop at higher temperatures (above 200 °C) is attributed to the decreased rate of water loss at these high temperatures. Water losses were found to increase abruptly between 200 and 300 °C and to increase gradually in the lower and higher temperatures range until 500 °C is reached. These changes in water loss are consistent with the changes in the heats of immersion in water, to a lesser extent with the changes in the heats of immersion in methanol and to a limited extent with the changes in the heats of immersion in carbon tetrachloride. Generally, the heats of immersion follow the order water > methanol > carbon tetrachloride; this has been related to changes in the chemistry of the alumina surface and is also discussed in relation to the porosity characteristics. From pore structure studies it was found that these samples contain both mesopores (or wide pores) and narrow pores (or micropores). After an analysis for the surface areas located in wide pores, the heats of immersion in water were found to follow the fraction of the area located in wide pores (or mesopores); this has been interpreted on the basis of a reduction in the mutual repulsions encountered between water molecules inside these mesopores or wide pores.

Changes in transepidermal water loss and the composition of epidermal lecithin after applications of pure fatty acid triglycerides to the skin of essential fatty acid-deficient rats

The importance of various unsaturated fatty acid triglycerides to the repair of faulty skin barrier function was studied in essential fatty acid-deficient rats. Following cutaneous application of the pure triglycerides for up to 5 days, the hitherto high rate of transepidermal water loss, characteristic of essential fatty acid deficiency in rats, was reduced by the triglycerides of linoleic and gamma-linolenic acids. Incorporation of the applied fatty acids into the lecithin of the epidermis accompanied these changes in water loss, indicating that cutaneously applied triglycerides may be metabolized by the skin and incorporated into complex lipids. Other fatty acid triglycerides, including alpha-linolenic, dihomo-gamma-linolenic, arachidonic and omega-7-heneicosatrienoic acid, did not lower the rate of transepidermal water loss, although all were incorporated into epidermal structural lipids. The non-essential oleic acid also had no effect upon the rate of transepidermal water loss. These data suggest that of the two main essential fatty acids that occur in skin, linoleic acid and arachidonic acid, the former specifically plays an important role in regulating barrier function whereas the later may have a separate function, such as serving as a precursor of prostaglandins.

THE EFFECTS OF IONIC CHANGES ON WATER TRANSFER ACROSS THE ISOLATED URINARY BLADDER OF THE TOAD BUFO MARINUS

SUMMARY 1. The effects of ionic changes in the bath fluids on water transfer across an in vitro preparation of the urinary bladder of the toad Bufo marinus were investigated. 2. Calcium was necessary to maintain the normal low permeability of the bladder to water in the absence of Pituitrin. Magnesium, strontium and manganese but not barium could substitute for calcium. 3. With low concentration of calcium there was a reduction in the water transfer across the bladder wall in response to Pituitrin and no other divalent ion could substitute for calcium. 4. Exclusion of potassium from the serosal side of the bladder reduced the water transfer in the presence of Pituitrin. Increase in potassium concentration above normal levels also inhibited the response to hormone. When no Pituitrin was present there was no change in water loss from the bladder with alterations in potassium concentration. Absence of potassium from the epithelial side of the bladder had no effect whether Pituitrin was present or not. 5. The presence of sodium on the epithelial side increased the water transfer in response to Pituitrin and neither lithium, choline nor potassium could substitute for it. Replacement of 50% of the sodium chloride on the serosal side of the bladder by choline chloride decreased the water transfer in response to Pituitrin.