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Abstract  

The flexibility of the internal structures of solids, both crystalline and amorphous, is a result of the freedom of the displacement of their elements, without disturbance of the continuity of the structure as a whole. This article discusses peculiarities of solids with flexible structures. The effects of flexibility in the thermal reactions of the creation of new compounds in the internal structure of solids, and the phase transitions, are considered. Flexibility is indispensable for random amorphous structure formation. The glass transition effect is a consequence of the high flexibility of the structure of glasses.

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Abstract  

Aqueous Pb(II) samples, spiked with210Pb/210Bi in secular equilibrium to study container adsorption, can provide some helpful insights if one takes advantage of the Cherenkov effect. While both radionuclides give high efficiencies when counted in a scintillator cocktail medium, only210Bi has a sufficiently energetic -particle to yield an appreciable count rate in a water medium. Thus, monitoring the cocktail-to-water count rate ratio can provide important clues as to what happens during adsorption. A significant change in the ratio indicates not only disturbance of the secular equilibrium relationship, but indicates which nuclide is preferentially adsorbed.

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The characteristics of crystallization, melting and spherulitic growth of a random propylene copolymer (PRC) containing small amount of ethylene were studied in the presence of a selective Β-nucleating agent (calcium pimelate). It was established that the products of isothermal and non-isothermal crystallization are very rich in Β-modification but have mixed polymorphic composition. The formation of α-modification may be attributed to Βα-transition on the surface of growing Β-spherulites resulting in αΒ-twin-spherulites. During melting of PRC of Β-modification, the characteristics observed with Β-nucleated propylene homopolymers, namely, a Βα-recrystallization of recooled samples and separated melting of non-recooled samples (i.e. the melting memory effect), as well as a ΒΒ-recrystallization leading to a perfection of the structure within the Β-modification, are also demonstrated. The disturbance of regularity of the polymer chain highly reduces the tendency to Β-crystallization. In contrast to the observations with propylene homopolymers, the growth rate of α-modification (G α) is higher than that of Β-modification (G β) and no critical crossover temperature can be found (T(Βα)=413 K) below whichG α>G β. The experimental results show that a partial disturbance of chain regularity by incorporation of comonomer units considerably reduces the tendency to Β-crystallization.

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Abstract  

Up to 14 elements were determined by NAA in tree rings of Norway spruce trees from two sites which differed in their degree of human disturbance mainly caused by phytotoxic SO2 pollutions. The aim of this study was to identify elements that might be useful to indicate environmental stresses. Significant site differences were found with Mn by finding high Mn concentrations and Mn accumulation rates as well as Mn/Ca ratios at the heavily polluted sites. This might indicate a long term soil pH change due to acid deposition. These results correspond well with data from the literature which also indicate Mn in xylem being a key index element for the health status of the tree.

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Abstract  

Differential scanning microcalorimetry (DSC) and UV–VIS absorption spectroscopy were used to obtain the characteristics of blood serum from newborn rat’ after maternal treatment with cyclophosphamide in comparison with control. The obtained DSC curves reveal a complex endothermic peak due to the unfolding process of various serum proteins. Thermal profiles and absorption spectra of blood serum are sensitive to the age of newborns as well as to effect of maternal administration of cyclophosphamide. The most significant disturbances in serum proteome were observed for 14-day old newborns. The thermodynamic parameters: enthalpy change (∆H), the normalized first moment (M1) of the thermal transition with respect to the temperature axis and the ratio of C p ex at 70 and 60 °C describing denaturation contributions of globulin forms in respect to unliganded albumin with haptoglobin was estimated. Moreover, the second derivative spectroscopy in the UV region was used to resolve the complex protein spectrum. The differences in blood serum detected by DSC and UV–VIS confirm a potential usefulness of these methods for diagnostic and monitoring changes with age as well as the pathological state of blood serum.

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Journal of Thermal Analysis and Calorimetry
Authors: S. Meenakshisundaram, S. Parthiban, R. Kalavathy, G. Madhurambal, G. Bhagavannarayana, and S. Mojumdar

Abstract  

The influence of heteroaromatic N-base (1,10-phenanthroline) (Phen), a new additive as complexing agent on tris(thiourea)zinc(II)sulphate (ZTS) crystals from aqueous solutions at 30 °C is investigated. Crystals were grown using low concentration of the dopant (0.005 M L−1) in the aqueous growth medium and the growth promoting effect (GPE) is much greater because of an increase in the metastable zone width. High dopant concentration decreases GPE. The crystalline perfection of the grown crystals is quite good both in doped and undoped crystals as evaluated by high-resolution X-ray diffractometry (HRXRD). The diffraction curve of a typical Phen doped as-grown ZTS crystal was observed to contain a single peak indicating that the crystal does not contain any epitaxial layer on the surface or internal structural grain boundaries. Not much variation is observed in FT-IR and XRD of pure and doped ZTS. Phen depresses the NLO efficiency of ZTS. It could be ascribed due to the disturbance of charge transfer in the presence of the dopant. The grown crystals were also characterized by UV–Vis, SEM and TG–DTA techniques.

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Abstract  

The activity of cesium-137 (Bq/kg) in surface soils between 2-5 cm was determined for more than ninety sample sites on the Araya Peninsula, the Paria Peninsula and the isthmus in between them in the state of Sucre (Venezuela). The measurements were performed by high-resolution gamma-ray spectroscopy, employing a compatible IBM computer with a Nucleus analog to digital interface card. In general, the values for the 137Cs activities were much greater on the Paria Peninsula than the Araya Peninsula and slightly lower on the isthmus. Even though the peninsulas are only separated by a small isthmus, their environmental characteristics are very different. The large difference in the annual rainfall of the peninsulas could have resulted in a greater amount of deposition of 137Cs on the Paria Peninsula, as well as other environmental characteristics, such as altitude and vegetation. The difference of the environmental characteristics could also affect the degree of disturbances of the soils by natural processes on the peninsulas and the isthmus, which could also have affected the 137Cs activity distribution. Finally, an anomalous high 137Cs activity distribution was found at the farthest southeastern sample sites and one of lesser extent at the most northern sample sites. These anomalies are possibly due the direct affect of the northeasterly winds which transported the 137Cs fallout from the nuclear weapon test sites.

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Abstract  

Thirty radioisotopes of iodine are known but only those with mass numbers from 123 to 135 are of major radiotoxicological interest. Exposure of animals or man to inorganic131I or125 I may result in the induction of benign or malignant thyroid tumors or depression of thyroid function; Bq for Bq125I is less toxic than131I. However, the shorter lived radioiodines132I,133I, and135I appear to be 10 to 100 X more toxic than131I alone. Adrenal, pituitary and ovarian tumours, as well as parathyroid hypofunction and other biochemical disturbances, have been reported in animals but not, so far, in man. Gonad doses from131I up to at least 800 mGy do not appear to cause in man an increased incidence of congenital abnormalities or spontaneous abortions. Little information is available about the toxicity of radioiodine containing organic compounds. The DNA precursor, iododeoxyuridine when labelled with125I becomes incorporated into the cell nucleus and produces severe and often irreparable damage due to the emission of Auger electrons. The risk estimate for the induction of thyroid carcinoma or adenoma by inorganic131I is considered to be 10 to 20·10−6 persons Gy−1 y−1, but may be up to 100 times larger for persons exposed to mixtures of short-lived radioiodines.

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Abstract  

In order to be more confident of the performance assessment of high-level radioactive waste disposal, radionuclide transport must be investigated in more detail in the disturbed host rock region adjacent to the engineered barriers where disturbance has been introduced during the construction and waste-emplacement period. Geochemical, hydrological, and rock-mechanical properties should be quite different from those of undisturbed host rock. We have to elucidate the effect of bentonite intrusion into intersecting fractures from the standpoint of radionuclide confinement. In the present work, sorption distribution ratios (Kd's) of Np and Am are measured experimentally for various values or redox potential (Eh) in a simulated rock fracture filled with bentonite. The Kd of Am is approximately 6.5×103 ml/g and found to be insensitive to the redox potential. Under anaerobic conditions, the Kd of Np is approximately 6×104 ml/g. Under aerobic conditions, Kd is as small as 30 to 100 ml/g. This is the first report to measure the sorption behavior of Np and Am in a simulated rock fracture filled with bentonite (namely, in a disturbed zone) under pH, Eh and ionic strength control. We aan make use of these Kd data for numerically evaluating the mass transfer from bentonite filled fractures into the water-flowing fracture network1.

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Fuzzy inference approach was applied to select the control input for the precision water bath of the heat exchange calorimeter used at a non-air-conditioned laboratory. The thermal fluctuation of the bath water was necessary to be kept within a narrow range. The cooling water or coolant kept at a temperature lower than the set temperature was circulated in the bath. The deviation corresponding to the difference between the set temperature and the observed temperature was observed as the input signal. The output or control input to be given to the heather element in the water bath was calculated by the fuzzy modus. The output function was simplified by means of circulating the cooling water. The contribution of each membership function was changed according to the thermal progress of the observed temperature of the water. The whole system including the control programs was examined by a practical water bath, and fairly good results were obtained. Reasonable recoveries were also shown for external thermal disturbances given to the controlled system.

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