Changes In Total Water Content Research Articles

The study of the water regulation mechanisms in the winter bread wheat varieties under an acute drought

Water regime of plants, characteristic of a certain variety, largely determines the resistance of plants to drought. Drought affects, first of all, such indicators as water absorption capacity, water retention capacity, water deficit and changes in total water content in the process of ontogenesis. Studying and taking into account a number of parameters of water regime can significantly increase the reliability of the assessment of plants for drought resistance. The purpose of the current study was to investigate the water regime of the winter bread wheat varieties under an acute drought and to select promising samples for breeding for drought resistance. The objects for the study were 7 winter bread wheat varieties developed by the FSBSI “Agricultural Research Center “Donskoy”. The study was carried out on the experimental plot (zasushnik) of the laboratory for plant physiology under an acute drought of 30% PV in 2017–2019. According to the study results, there have been identified the varieties ‘Zhavoronok’, ‘Volnitsa’ and ‘Volny Don’, which were characterized by the largest increase in water-absorbing capacity (from 40.0 to 41.1%); by a minimum increase in water deficit (1.3–2.1%); by the smallest decrease (3.2–3.8%) in the total water content in fibers due to adaptability to water stress conditions in spite of increasing drought. There has been recommended to introduce these samples into the breeding process aimed at developing drought-resistant winter bread wheat varieties.

Longitudinal changes in myelin water fraction in two MS patients with active disease

Multiple sclerosis (MS) is characterised by focal areas that undergo cycles of demyelination and remyelination. Although conventional magnetic resonance imaging is very effective in localising areas of damage, these techniques are not pathology specific. A newer technique, T 2 relaxation, can separate water from brain into three compartments: (1) a long T 2 component (> 2 s) arising from CSF, (2) an intermediate T 2 component (~ 80 ms) attributed to intra- and extra-cellular water and (3) a short T 2 component (~ 20 ms) assigned to water trapped in between the myelin bilayers (termed myelin water). Histological evidence shows that myelin water is a specific marker of myelination. The goal of this work was to follow changes in total water content (WC) and myelin water fraction (MWF) in evolving MS lesions over one year. Multi-echo T 2 relaxation data was collected and used to measure water content and myelin water fraction from three new MS lesions in two patients. WC increased in the three large (> 1 cm 3) lesions at lesion appearance and remained elevated in the central core. Two lesions showed low MWF in the core suggesting demyelination upon first appearance. At later time points, one lesion showed a decrease in volume of low MWF, reflecting remyelination whereas the volume of low MWF in the other lesion core remained constant. This work provides evidence that MWF and WC can monitor demyelination and remyelination in MS.

Development of hypoosmoregulatory ability in allis shad Alosa alosa

When different ages of juvenile allis shad Alosa alosa (18–74 days post‐fertilization) were exposed for 48 h to elevated salinity (25 or 30), all ages could tolerate moderates salinity (25) whereas only the older stages could tolerate the higher salinity. In 88 days post‐fertilization allis shad, acclimatation to full‐strength sea water for 2 weeks did not lead to significant changes in total water content and gill Na+/K+‐ATPase activity whereas total Na+ content increased within 5 days to values which remained stable thereafter. Together, these data suggest that juvenile allis shad develop a limited euryhalinity, which allows them to fully adapt to hyperosmotic environment immediately after transfer.

The effect of ageing on the water-holding capacity of pork: role of cytoskeletal proteins

The water-holding capacity (WHC) of pork decreases post-mortem but has been shown to increase during subsequent ageing. In order to test a hypothesis that water-holding capacity increases during ageing due to degradation of the cytoskeleton, WHC was followed 10 days post-mortem and related to the extent of proteolysis of cytoskeletal proteins. A fast method for measuring WHC in small meat samples was developed by the use of centrifugation. The WHC of fresh pork decreases in the first part of post-mortem storage after which it increases to the level of 1 day PM. No changes in total water content of the meat were observed which could explain changes in WHC during ageing. Vinculin and desmin degrade gradually during ageing while talin degrades rapidly. These observations are consistent with the hypothesis that degradation of the cytoskeleton slowly removes the linkage between lateral shrinkage of myofibrils and shrinkage of entire muscle fibres, so removing the force that causes flow into the extracellular space. Inflow of previously expelled water is then possible, so increasing WHC as observed in later periods of storage.

Water in Skeletal Carbonates

ABSTRACT Studies of a wide variety of modern and fossil skeletal carbonates indicate they all contain water in amounts ranging from a few tenths of one percent to as much as three percent by weight. The word water is used as a general term to include all inorganic liquid and bound H2O and OH-. Reflectance spectroscopy in the visible and near infrared (0.60 to 2.55 µm) reveals major differences among skeletal carbonates in the amount of water present, phases in which it occurs, and relative proportions of these phases. Liquid H2O is present in all skeletal material studied in the form of fluid inclusions. In some cases, most notably the molluscs, H2O is also associated with an organic matrix. A hydrated CaCO3 phase occurs in so e biogenic low-Mg calcites (LMCs) and aragonites, and two hydrated MgCO3 phases with differing bond energies occur in high-Mg calcites (HMCs). Many HMCs contain Mg(OH)2 and H2O bound to CaCO3 as well, and some biogenic aragonites contain Ca(OH)2. Water content varies with skeletal mineralogy, taxonomic group, and, in the case of the molluscs, with skeletal structure. Alteration of aragonites and HMCs to LMCs is accompanied by order-of-magnitude changes in total water content. HMCs lose bound H2O and OH during alteration to LMCs. Ca(OH)2 and H2O bound to CaCO3may also be lost from biogenic aragonites, even in the absence of changes in bulk mineralogy. LMCs also lose H2O bound to CaCO3 during diagenesis. Fluid inclusions are lost during neomorphic alteration of aragonites and LMCs. However, skeletal material that retains its original bulk skeletal mineralogy and/or original microstructure as seen in thin section also retains the bulk of its original fluid inclusion content. Water content can be used as a criterion for monitoring diagenetic alteration in carbonates. Water present in fluid inclusions can serve as a medium for diagenetic reactions. Bound H2O lost on heating could take part in diagenetic reactions during deep burial as well.

Monitoring Changes in Total and Unfrozen Water Content in Seasonally Frozen Soil Using Time Domain Reflectometry and Neutron Moderation Techniques

This paper presents the results of a study utilizing time domain reflectometry and the neturon moderation technique to monitor changes in total water content and unfrozen water content during fall, winter, and spring on a sandy loam site which was maintained snow free to maximize seasonal frost penetration. Soil temperatures were recorded continuously, and meteorological conditions were observed at a nearby climatological station. The procedure of combining the neutron probe and time domain reflectometry employed here showed good potential for augmenting the limited data on soil moisture redistribution in freezing soils under natural conditions. The data indicated the importance of obtaining a representative spatial average of water content measured with time domain reflectometry in order to obtain a good correspondence with neutron probe observations.

332. High current gas discharges: A. A. Ware, Rep. Progr. Phys., 1961, 24

The solution of three-dimensional diffusion equations is discussed with respect to the applicability of a √t relationship to describe diffusion. The kinetics of the rates of H2O sorption and of D2O-H2O exchange have been followed in the zeolites chabazite, gmelinite and heulandite in the temperature range 30–80°C, and intrinsic diffusion coefficients and self-diffusion coefficients of water in the crystal evaluated from the respective sets of measurements. Self-diffusion coefficients in all three zeolites have values intermediate between the self-diffusion coefficients of liquid water, at the same temperature, and ice near its melting point. Small changes in total water content near saturation produce a slight decrease in the self-diffusion coefficients in chabazite and gmelinite and a more marked decrease in heulandite. Using equilibrium sorption data it is shown that the equation D = D∗ (dlnadlnc) is a reasonably satisfactory description of the relationship between the diffusion coefficients and this provides an indication that both intrinsic and self-diffusion processes involve molecules as diffusing units.

The diffusion and sorption of water in zeolites—II. Intrinsic and self-diffusion

The solution of three-dimensional diffusion equations is discussed with respect to the applicability of a √ t relationship to describe diffusion. The kinetics of the rates of H 2O sorption and of D 2O-H 2O exchange have been followed in the zeolites chabazite, gmelinite and heulandite in the temperature range 30–80°C, and intrinsic diffusion coefficients and self-diffusion coefficients of water in the crystal evaluated from the respective sets of measurements. Self-diffusion coefficients in all three zeolites have values intermediate between the self-diffusion coefficients of liquid water, at the same temperature, and ice near its melting point. Small changes in total water content near saturation produce a slight decrease in the self-diffusion coefficients in chabazite and gmelinite and a more marked decrease in heulandite. Using equilibrium sorption data it is shown that the equation D = D∗ (dln a d lnc) is a reasonably satisfactory description of the relationship between the diffusion coefficients and this provides an indication that both intrinsic and self-diffusion processes involve molecules as diffusing units.