The Thermal Properties and Firing Characteristics of Zr/KClO4 Priming Compositions Containing Graphite,Fe2O3 and Al2O3 additives

Thermal decomposition of Zr/KClO₄ priming compositions containing different concentration of additives, such as graphite, Fe₂O₃ and Al₂O₃ have been studied by DSC/TG techniques. The firing characteristics of these primer mixtures have also been examined by Bruceton test and by adiabatic calorimeter. The results of these experiments suggest that strong interaction has been occurred between KClO₄ and Fe₂O₃ in the solid state. This revised version was published online in July 2006 with corrections to the Cover Date.     

A Thermal Decomposition Study of Individual and Co-Precipitated Y, Ba and Cu Oxalates

Y-Ba-Cu oxalate powder with a presumed Y:Ba:Cu molar ratio of 1:2:4 was prepared by a modified co-precipitation method and its solid-phase thermal decomposition was studied from 25 to 1000°C, the major evolved gases being H₂O and CO₂. The air-dried powder contained residual moisture. It required isothermal heat treatment for elimination of the evolved gases. The melting point of the co-precipitation Y-Ba-Cu oxalate powder, determined by DSC at a heating rate of 10°C min⁻¹ was approximately 882°C in N₂, 949°C in air and about 979°C in O₂. The dependence of the sintering properties of this material upon the atmosphere and the temperature is considered. This revised version was published online in August 2006 with corrections to the Cover Date.     

Kinetic study of Y, Ba, Cu oxalates and coprecipitated Y-Ba-Cu oxalate

The kinetics of the decomposition of Y, Ba and Cu oxalates and coprecipitanted Y-Ba-Cu oxalate was investigated under a nitrogen atmosphere on the basis of dynamic thermogravimetric data, the average activation energies of the decomposition of Y, Ba and Cu oxalates were obtained from the slopes of the T. Ozawa plot. The average activation energies for the dehydration of these oxalate and coprecipitated Y-Ba-Cu oxalate were also evaluated from the thermogravimetric curves.     

A Study on the Thermal Behaviour of Solder Glass

Vitreous solder glasses, such as Mansol #40 and FEG-2002, are commercialized solder glasses, which are compression sealing glasses that can be used to solder materials with expansions between 55-68⊙10^-7°C^-1, such as Al₂O₃. In order to understand and tailor the thermal behaviour of solder glasses, cylindrical-like glasses were first carefully ground with a stainless steel mortar and pestle. Initially, no exothermic or endothermic data were obtained from the DTA/DSC curves except those relating to melting. However, exothermic peaks appeared after the glass samples were re-melted. In this work, kinetic parameters such as the activation energy, and the morphology of the devitrification mechanisms for two kinds of solder glasses were also investigated, using non-isothermal DTA techniques. The activation energies ranged from 220 to 235 kJ mol^-1 and the devitrification mechanism parameters were close to 1. This indicates that the devitrification mechanisms of the two kinds of solder glasses involve surface nuclei. This revised version was published online in July 2006 with corrections to the Cover Date.     

The NIST natural-matrix radionuclide standard reference material program for ocean studies

In 1977, the Low-level Working Group of the International Committee on Radionuclide Metrology met in Boston, MA (USA) to define the characteristics of a new set of environmental radioactivity reference materials. These reference materials were to provide the radiochemist with the same analytical challenges faced when assaying environmental samples. It was decided that radionuclide bearing natural materials should be collected from sites where there had been sufficient time for natural processes to redistribute the various chemically different species of the radionuclides. Over the succeeding years, the National Institute of Standards and Technology (NIST), in cooperation with other highly experienced laboratories, certified and issued a number of these as low-level radioactivity Standard Reference Materials (SRMs) for fission and activation product and actinide concentrations. The experience of certifying these SRMs has given NIST the opportunity to compare radioanalytical methods and learn of their limitations. NIST convened an international workshop in 1994 to define the natural-matrix radionuclide SRM needs for ocean studies. The highest priorities proposed at the workshop were for sediment, shellfish, seaweed, fish flesh and water matrix SRMs certified for mBq per sample concentrations of ⁹⁰ Sr, ¹³⁷ Cs and ²³⁹ Pu + ²⁴⁰ Pu. The most recent low-level environmental radionuclide SRM issued by NIST, Ocean Sediment (SRM 4357) has certified and uncertified values for the following 22 radionuclides: ⁴⁰ K, ⁹⁰ Sr, ¹²⁹ I, ¹³⁷ Cs, ¹⁵⁵ Eu, ²¹⁰ Pb, ²¹⁰ Po, ²¹² Pb, ²¹⁴ Bi, ²²⁶ Ra, ²²⁸ Ra, ²²⁸ Th, ²³⁰ Th, ²³² Th, ²³⁴ U, ²³⁵ U, ²³⁷ Np, ²³⁸ U, ²³⁸ Pu, ²³⁹ Pu + ²⁴⁰ Pu, and ²⁴¹ Am. The uncertainties for a number of the certified radionuclides are non-symmetrical and relatively large because of the non-normal distribution of reported values. NIST is continuing its efforts to provide the ocean studies community with additional natural matrix radionuclide SRMs. The freeze-dried shellfish flesh matrix has been prepared and recently sent to participating laboratories for analysis and we anticipate receiving radioanalytical results in 2000. The research and development work at NIST produce well characterized SRMs that provide the world's environment-studies community with an important foundation component for radionuclide metrology.     

Fabrication, characterization, and application of greigite nanoparticles for cancer hyperthermia

Greigite is a Fe-S-containing complex having magnetic properties mainly synthesized in the solution. In the present study, greigite was synthesized by a coprecipitation method at different pH's and reaction times. The greigite phase was analyzed by the X-ray diffraction (XRD) method at an optimum pH of 3.0 and reaction time of 10 min, respectively. The magnetization characterization by superconducting quantum interference device (SQUID) revealed that the magnetic saturation was obtained at 16.1538 (emu/g). The inductive heating property of the greigite nanoparticles was carried out by induction heater power cube (IHPC) in an alternating current magnetic field and the results indicated that the heating effect was significant. Transmission electron microscopy (TEM) revealed that the size of the greigite was around 50-100 nm and the edges of nanoparticles have no clear boundary or distinctive morphology. Studies on LDH and WST-I assay revealed low cytotoxicity at greigite concentrations of 1 mg/ml. In vitro experiments suggested that cancerous cells, human lung adenocarcinoma epithelial cell line (A549), had the ability to become more damaged under AC magnetic field than the normal human lung cells (HFL-1).