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Abstract  

The differences in bound water content of beef semimembranous muscle samples obtained from previously chilled (24 h at +4°C) middle-aged beef carcasses were determined by the use of DSC. Initially, samples obtained from fresh, unprocessed meat were frozen at −40, −50 or −65°C to determine their melting peaks for freezable water (free water) content with the use of DSC. The samples were then subjected to an environment with an ambient temperature of −30, −35, −40 or −45°C, with no air circulation, or with an air circulation speed of 2 m s−1, until a thermal core temperature of −18°C was attained; this was followed by thawing the samples until a thermal core temperature of 0°C was reached. This process was followed by subjecting the samples to the ambient temperatures mentioned above, to accomplish complete freezing and thawing of the samples, with DSC, and thereby determination of the freezable water contents, which were then used to determine the peaks of melting. The calculated peak areas were divided by the latent heat of melting for pure water, to determine the freezable water contents of the samples. The percentage freezable water content of each sample was determined by dividing its freezable water content by its total water content; and the bound water content of each sample was determined by subtracting the percentage free water content from the total. In view of the fact that the free water content of a sample is completely in the frozen phase at temperatures of −40°C and below, the calculations of free and bound water contents of the samples were based on the averages of values obtained at three different temperatures.

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Abstract  

Tetronic® comprises X-shaped copolymers formed by four poly(propylene oxide) (PPO) and poly(ethylene oxide) (PEO) block chains bonded to an ethylene diamine central group. Micellization behaviour of three representative Tetronics (T304, T904 and T1307) was characterized to gain an insight into the interactions between the copolymer unimers and the state of water in their solutions. The enthalpy of demicellization, recorded at 37°C in an isoperibol microcalorimeter, indicated that the process was in all cases exothermic and the enthalpy ranked in the order T1307≥T904>>T304. Micellization is entropy-driven owing to hydrophobic interactions between the PPO chains. DSC analysis showed that the crystallization and melting peaks of the free water remaining in T304 and T904 solutions were progressively shifted toward lower temperatures as the surfactant proportion increased, owing to a colligative effect. Bound water corresponded to 3 water molecules per EO repeating unit. In the case of T1307, which has longer PEO chains, a splitting of the melting peak was observed, one peak appearing around 0°C due to free water and another at –15°C due to interfacial water. As T1307 proportion raised, the enthalpy of the former decreased, whilst the enthalpy of the latter increased. In 40% T1307 solutions, interfacial water overcame the proportion of free water; there being 1 interfacial and 3 bound water molecules per EO repeating unit. Gaussian deconvolution of FTIR spectra also enabled to characterize the evolution of free water as a function of Tetronic proportion. The dependence of micellization and water interaction behaviour on Tetronics structure should be taken into account to use these copolymers as drug solubilizers and micellar carriers.

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) profile for Ca 2+ –Mon in Fig. 6 demonstrates a big and wide endothermic with the T m around 57.92 °C. The endothermic ( H Mon = 356.3 ± 0.1 J/g) that appears in the range of 30–100 °C indicates the removal of free water molecules, which are

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free water clearance (CH 2 O), the osmolar clearance was calculated with the following equation: Cosm = (urine osmolarity × total urine volume)/plasma osmolarity. CH 2 O was calculated using the following equation: CH 2 O = total urine volume

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Journal of Thermal Analysis and Calorimetry
Authors: Elisabetta Princi, Silvia Vicini, E. Pedemonte, Valeria Arrighi, and I. McEwen

Summary Natural polymers, as cellulose, with hydrophilic groups such as hydroxyl groups have various strengths of interaction with water. Cellulose is a structurally heterogeneous polymer, consisting of paracrystalline and amorphous domains. Water can interact with the amorphous domains, but it is excluded almost completely from the crystalline regions. The purpose of this study was to estimate the amount of bulk free water in cellulose based materials, as linen, cotton and paper, by measuring the heats of vaporisation. Moreover the amount of free water in oxidised and grafted samples has been determined by DSC and this quantity has been compared with that found in the corresponding native materials. In oxidised cellulose the water content increases with decreasing the degree of crystallinity; the oxidation, being a degradative reaction, modifies the amorphous content in the cellulose. In presence of acrylic grafted polymer, the free water content is reduced and this reduction is related to the grafting yields.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: S. Hisamatsu, T. Ohmura, Y. Takizawa, T. Katsumata, Y. Inoue, M. Itoh, K. Ueno, and M. Sakanoue

Abstract  

Tritium concentrations are reported for diet and human tissue samples collected in the Akita district of northern Japan. Sixteen separate food group samples and a total diet sample were collected for Akita City during April and May 1987. Six samples of heart and nine samples of kidney tissue were collected from 10 decreased individuals in Akita Prefecture from January to July 1986. Five serum and four blood samples were also obtained in Akita Prefecture from December 1985 to June 1986. Free water3H concentration as well as tissue-bound3H were determined separately. Specific activity ratios of tissue-bound3H to free water3H in the samples were almost between 1.0 and 2.0 and were similar to our previous results for food samples and other tissue samples. The specific activity ratio was also found to be lower than that reported in the U.S.A. and significantly lower than in Europe.

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Abstract  

All of the combustion water samples extracted from cellulose in pine tree rings corresponding to the 1983–1987 period showed elevated tritium concentrations of approximately 65 pCi/dm3, which were 30 to 35 pCi/dm3 higher than those for precipitation and atmospheric vapor in recent years. In addition, other environmental samples, viz. the tissue-free water in tree rings, and of combustion and tissue-free water in pine needles and spring water near the pine tree site also showed concentrations similar to the combustion water of cellulose. These findings suggest that most of the tritium in tree rings was supplied from underground water containing a high tritium concentration in the root zone of the pine tree.

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Abstract  

Zero-point vibration energy differences for all possible 12 isotopomers of the water dimer have been evaluated using various modifications of MCY potential combined with the intramolecular force field of free water molecule. In agreement with observation, in isomeric pairs of H- and D-bonded dimers the latter have been proved, both through computation and partly also by a general reasoning, to be more stable.

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Abstract  

Variation of tritium concentration was examined for 100 days in the course of degradation of fresh pine needles, which were left on a pine forest floor. No difference was observed on free water tritium (FWT) and organically bound tritium (OBT) concentrations of sterilized samples by gamma-ray irradiation or fumigation and control samples, attributable to incomplete sterilization. The OBT concentrations did not increase within the experimental period as the level of humus collected from the forest floor. The results suggest that a longer degradation time, more than 100 days, is necessary to elevate OBT up to the level, which is observed in the general environment.

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