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Abstract  

Adaptive or smart hybrid composites consisting of a polymer matrix reinforced by aramid fibres and incorporating pre-strained Shape Memory Alloy (SMA) wires are able to tune some of their properties, such as their shape, the natural vibration frequency or the damping coefficient, in response to an external stimulus. The functional properties of these systems are directly related to the reversible martensitic transformation in the SMA elements. In this work the transformational behaviour of both free SMA wires and SMA wires embedded in polymer matrix is investigated by means of DSC. The martensitic transformation of the constrained wires is impeded by the polymer matrix, while the interface integrity plays a crucial role.

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Abstract  

Thermal properties, ageing resistance and flammability of peroxide vulcanizates of butadiene-acrylonitrile rubber Perbunan NT 1845 (NBR) of Bayer, modified in bulk and on a surface with synthesized hybrid functional poly(methylsiloxanes) were investigated. The derivatographic, DSC, oxygen index and FTIR methods were applied. It was stated that addition of poly(methylsiloxanes) caused distinct increase of ageing resistance and of NBR vulcanizates and decrease of their thermal decomposition rate and flammability, providing self-extinguishing samples. The mechanism of addition reactions of Si–H bond to multiple bonds of NBR has been proposed.

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Abstract  

FTIR thermal analysis was used for a hybrid xerogel, anilinepropylsilica, obtained from three different organic precursor amounts, using HF and NaF as catalysts in the sol–gelprocess. The aniline ring vibrational mode at 1500 cm−1 of attached aniline groups was used to obtain the relative aniline content in the xerogel materials after being submitted to thermal treatment in the temperature range from 100 to 400C. This technique allowed to evaluate the thermal stability of organic phase. The organic coverage on the surface and the fraction of trapped organic groups in closed pores can also be evaluated.

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Abstract  

A hybrid stable iodine/radioiodine (131I) atmospheric photochemistry box model, including 27 reactions, has been developed and solved using algorithmic programme with the application of the Runge-Kutta method of the order 4(5). This modelling offers a clearer view of relationship among aerosol-associated (inorganic iodine compounds, mostly I2O2), gaseous inorganic (mostly IONO2, HOI) and organic (CH3I) iodine compounds in ambient atmosphere. Summing up the data of the Chernobyl accident, the problem of the standardised method for atmospheric aerosol-associated and gaseous (inorganic and organic) radioiodine activity measurements in the case of the nuclear power plant accident is discussed.

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Abstract  

Most studies report a depression of the glass transition temperature in thin polymer films. To gain insight into this behavior, we have simultaneously investigated the structure of materials and their thermal behavior by developing an ATR–FTIR–nano-differential scanning calorimeter (nanoDSC) hybrid instrument consisting of a ZnSe ATR crystal upon which the sample and a DSC-on-a-chip rests. FTIR spectra showed property changes with film thickness; nanoDSC did not. The relative absorbance of an IR peak at 797 cm−1 was found to correlate with aging time in thin films, suggesting that conformational structure of thin films is critical to their thermal behavior.

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Journal of Thermal Analysis and Calorimetry
Authors: Sangram Samal, Elizabeth Fernandes, Federica Chiellini, and Emo Chiellini

Abstract  

In the present study polymeric membranes consisting of poly(vinyl alcohol) (PVA) and multi-walled carbon nanotubes (MWCNTs) were prepared by casting method and their morphological, thermal and de-swelling behaviour were characterized. The effect of MWCNTs in the hybrid membranes was more significant when its concentration was high. The thermo degradation (T d) and crystallization (T c) temperatures of PVA increased of 10 and 9 °C, respectively in presence of 50 × 10−2 w v−1% of MWCNTs (PVNT3). Besides, the amount of non-free water increases with increasing of MWCNTs probably due to a capillary effect.

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Abstract  

Organic–inorganic hybrid composites of epoxy and phenyltrisilanol polyhedral oligomeric silsesquioxane (Ph7Si7O9(OH)3, POSS-triol) were prepared via in situ polymerization of epoxy monomers. The nanocomposites of epoxy with POSS-triol can be prepared in the presence of metal complex latent catalyst, aluminum triacetylacetonate ([Al]) for the reaction between POSS-triol and diglycidyl ether of bisphenol A (DGEBA). The dispersion morphology of organic–inorganic hybrid was characterized by scanning electronic microscopy (SEM). The thermostability of composites was evaluated by thermal gravimetric (TG) analysis. The flammability was evaluated by cone calorimeter test. The presence of [Al] latent catalyst leads to a decrease in combustion rate with respect to epoxy and epoxy/POSS composites as well as reduction in smoke, CO and CO2 production rate. The effect of [Al] is to reduce the size of spherical POSS particles from 3–5 μm in epoxy/POSS to 0.5 μm in epoxy/POSS[Al]. Furthermore, POSS with smaller size may form compact and continue char layer on the surface of composites more efficiently.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: M. L. Bonardi, F. Groppi, H. S. Mainardi, V. M. Kokhanyuk, E. V. Lapshina, M. V. Mebel, and B. L. Zhuikov

Summary  

High specific activity 64Cu is a radionuclide of increasing interest for PET imaging, as well as systemic and targeted radioimmunotherapy of tumours. The cross sections for production of 64Cu from Zn target of natural isotopic composition were measured in the proton energy range from 141 down to 31 MeV. The stacked-foil technique was used at 160 MeV intersection point of INR proton-LINAC in Troitsk, Russia. Several Ga, Zn, Cu, Ni, Co, V and Mn RNs were detected in Zn targets at the EOB. The activity of no-carrier-added 64Cu was measured through its only gamma-emission of 1346 keV (0.47% intensity). To this purpose, it was necessary to carry out a selective radiochemical separation of Ga RNs from the bulk of irradiated Zn target and other RNs. Theoretical calculations of cross sections were carried out with the CEF model and HMS-ALICE hybrid model codes and are compared with the experimental values.

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Abstract  

Certifications of trace elements in existing CRMs, especially biological CRMs, are far from satisfactory. Neutron activation analysis (NAA) for its inherent advantages combined with newly established parametric standardization, may contribute to improve this situation. The continuing progress of the hybrid extended k 0-relative NAA technique developed in our laboratory is discussed. Examples are given to show the reliability of the method in certification of multielements. RNAA is still one of the best methods, or even the method of choice, in analysis at sub-g/g concentration levels. The suitability of the technique for this purpose has been studied through the determination of rare earth elements at ng/g concentration level in two Chinese biological CRMs using both RNAA and ICPMS. Sampling behaviors of multielements in CRMs have been studied by INAA in an effort to develop CRMs suitable for analysis with small sample sizes.

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Abstract  

In divalent tin halides, when the halogen is small and highly electronegative (F, Cl), the tin valence orbitals are hybridized, the tin(II) non-bonded electron pair is located on one of the hybrid orbitals, and the resulting large electric field gradient gives a large quadrupole splitting. The reaction of barium chloride and tin difluoride in aqueous solutions, for large BaCl2.2H2O/SnF2 ratios (>10) results in the precipitation of a white powdered material, which is identified by X-ray diffraction to be BaCIF. However, Tin-119 Mossbauer spectroscopy shows the material contains a fairly large amount of divalent tin in the Sn2+ ionic form, with unhybridized orbitals, like in SnCl2. Using X-ray diffraction, we have established that Sn2+ ions substitute 15% of the Ba2+ ions at random, and chemical analysis shows the material has the formula Ba5.66SnCl7.30F6.04 and thus is enriched in chlorine.

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