Authors:R. Alvarez, A. Dougan, M. Rowland, and T. Wang
A non-destructive analysis technique using a protable, electric ion-tube neutron source (INS) and gamma ray detector has been used to identify the key constituent elements in a number of sealed munitions, and from the elemental makeup, infer the types of agent within each. The high energy (14 MeV) and pulsed character of the neutron flux from an INS provide a method of measuring, quantitatively, the oxygen, carbon, and fluorine content of materials in closed containers, as well as the other constituents that can be measured with low-energy neutron probes. The braod range of elements that can be quantitatively measured with INS-based instruments provides a capability of verifying common munition fills; it provides the greatest specificity of any portable neutron-based technique for determining the full matrix of chemical elements in completely unrestricted sample scenarios. The specific capability of quantifying the carbon and oxygen content of materials should lead to a fast screening technique which, can discriminate very quickly between high-explosive and chemical agent-filled containers.
Organic peroxides (OPs) have caused many momentous explosions and runaway reactions, resulting from thermal instability, chemical
pollutants, and even mechanical shock. In Taiwan, dicumyl peroxide (DCPO), due to its unstable reactive nature, has caused
two thermal explosions and runaway reaction incidents in the manufacturing process. To evaluate thermal hazards of DCPO in
a batch reactor, we studied thermokinetic parameters, such as heat of decomposition (†Hd), exothermic onset temperature (T0), maximum temperature rise ((dT/dt)max), maximum pressure rise ((dP/dt)max), self-heating rate (dT/dt), etc., via differential scanning calorimetry (DSC) and vent sizing package 2 (VSP2).
Authors:T. Wang, Y. Lu, M. Zhu, J. Zhang, and S. Ji
The critical furnace chamber temperature (T′ign) of the thermal explosion synthesis reaction Ti+3Al→TiAl3 is studied by isothermal and non-isothermal DSC. The reaction product is characterized by using the X-ray powder diffraction.
The value of T′ign is between 740 and 745C obtained from the isothermal DSC observations, and 729C obtained from non-isothermal DSC curves.
It shows that these two values have a good consistency. With the help of the apparent activation energy of the reaction obtained
by Friedman method and the value of T′ign0 by the multiple linear regression of the T′igns at different heating rates (β), the critical temperature (Tb) of thermal explosion for Ti–75at%Al mixture is estimated to be 785C.
Authors:B. Feng, Z.B. Xu, X. Wang, F. Jiang, G.J. Zhao, C. Xiang, and T. Wang
High molecular weight (HMW) glutenin subunits are important seed storage proteins in wheat and its related species. Novel HMWglutenin subunits in Aegilops tauschii accession of TA2484 were detected and characterized. SDS-PAGE analysis revealed the y-type subunit from TA2484 displayed similar electrophoretic mobility compared to that of 1Dy12 subunit. However, the electrophoretic mobility of x-type subunit was faster than that of 1Dx2 subunit. The primary structure of the two cloned subunits from TA2484 was similar to that of the x- and y-type subunits reported before. However, the 148 residues of the x-type subunit, which contained the sequence element GHCPTSLQQ, in the middle of the repetitive domain was quite different from other x-type subunits. Moreover, the 68 residues in this region were identical to those of the y-type subunits from the same accession. Consequently, 1Dx2.3*t (x-type subunit of TA2484) contains an extra cystenin residue located at the repetitive domain, which is novel compared to the x-type subunits reported so far. Phylogenetic analysis indicated that two subunits from accession TA2484 were in the x- and y-type subunit cluster, but bootstrapping value of 100% gave high support for the spilt between two subunits (1Dx2.3*t and 1Dy12.3*t) and their alleles, respectively. A hypothesis on the genetic mechanism generating this novel sequence of 1Dx2.3*t subunit is suggested.
Authors:S. Wang, Z. Tan, Y. Di, F. Xu, M. Wang, L. Sun, and T. Zhang
As one primary component of Vitamin B3, nicotinic acid [pyridine 3-carboxylic acid] was synthesized, and calorimetric study and thermal analysis for this compound
were performed. The low-temperature heat capacity of nicotinic acid was measured with a precise automated adiabatic calorimeter
over the temperature rang from 79 to 368 K. No thermal anomaly or phase transition was observed in this temperature range.
A solid-to-solid transition at Ttrs=451.4 K, a solid-to-liquid transition at Tfus=509.1 K and a thermal decomposition at Td=538.8 K were found through the DSC and TG-DTG techniques. The molar enthalpies of these transitions were determined to be
ΔtrsHm=0.81 kJ mol-1, ΔfusHm=27.57 kJ mol-1 and ΔdHm=62.38 kJ mol-1, respectively, by the integrals of the peak areas of the DSC curves.
Authors:T. Saito, J. Wang, T. Kitazawa, M. Takahashi, M. Takeda, M. Nakada, T. Nakamoto, N. Masaki, T. Yamashita, and M. Saeki
Four types of neptunyl(VI) hydroxides have been synthesized by chemical oxidation of Np(IV) instead of ozone oxidation of
Np(V) which caused the partial oxidation to the heptavalent state. NpO2(OH)2 (I) and NpO2(OH)2·H2O (orthorhombic type) (II) have been obtained by adding pyridine to the solution at 373K and 343K, respectively. NpO2(OH)2·H2O (hexagonal type) (III) and NpO2(OH)2·xH2O·yNH3 (x+y=1) (IV) have been prepared by using LiOH and NH4OH, respectively. The four materials have been characterized by X-ray powder diffraction patterns, thermogravimetric analysis
and237Np Mössbauer spectra. The237Np Mössbauer spectrum of (I) measured first time as anhydrous neptunyl(VI) hydroxide (δ=−46.2 mm/s,e2qQ=193 mm/s and η=0.16 at 4.8K) has more distinct five-line Mössbauer pattern than those of (II), (III) and (IV). The Mössbauer
spectra for (II), (III) and (IV) are slightly different from each other. The structural information has been obtained from
Authors:Q. Wang, K. Masumoto, K. Bessho, H. Matsumura, T. Miura, and T. Shibata
An infrared furnace (ULVAC RHL-410P) was newly applied to the extraction of tritium from concrete samples. After studying the tritium recovery yield regarding temperature and time, the best extraction conditions were set to 800 °C (setting temperature) for 30 minutes under Ar-gas flow of 200 ml/min. Tritium was collected in two cold traps and transferred to a vial for liquid scintillation counting. It took about one hour for the extraction of tritium. Reproducibility and recovery yield of tritium were about 100% compared to the values obtained by the ordinary heating method using an electric furnace. Gamma-ray emitters and tritium of concrete samples collected from several accelerator facilities have been determined. The specific activity of tritium strongly correlated with that of 152Eu and 60Co, so it was found that tritium was produced by thermal neutron reaction by the 6Li(n,)3H reaction. The results indicate that the tritium specific activity in concrete can be estimated from the 60Co specific activity obtained easily by -ray measurement.
Authors:Q. Wang, K. Masumoto, K. Bessho, H. Matsumura, T. Miura, and T. Shibata
For evaluation of radioactivity induced in the concrete samples from accelerator facilities, the residual radioactivity in
concrete sample, collected from seven accelerator facilities, was determined by γ-ray spectrometry. The tritium was extracted
by the heating method using an IR furnace, and measured with a liquid scintillation counter. It was found that the major radioisotopes
activated mainly by neutrons in the concrete samples were 152Eu, 60Co, 134Cs and 3H. The concentrations of radioactivities induced by thermal neutron capture are the highest at a depth of 10 cm in the concrete
wall. The correlation between tritium, 60Co and 152Eu activity was investigated by measuring many concrete samples for seven accelerator facilities. The results indicate that
their activities are strongly correlated with each other. So it would also be concluded that the total activity in shielding
concrete could be estimated on the basis of the activities of 60Co and 152Eu.
Authors:M. Wang, S. Tokiwa, T. Nishide, Y. Kasahara, S. Seki, T. Uchida, M. Ohtsuka, T. Kondo, and Y. Sawada
Amorphous indium-tin-oxide (ITO) transparent conducting film (15 at% Sn; thickness, 150–190 nm) was deposited on silicon wafer
at room temperature by RF magnetron sputtering for temperature programmed desorption (TPD) in vacuum. The thermal crystallization
was accompanied by evolution of water vapor (the main gas), argon and carbon dioxide. The total amount of evolved water vapor
(H2O [mol]/(In [mol]+Sn [mol])>0.2) was one or two orders of magnitude more than that from the nanocrystalline ITO films reported
in our previous papers. The thermal change of amorphous ITO film was remarkably affected by the position of the substrate.
An abrupt gas evolution was characteristic of the amorphous ITO films deposited on the position near the target center. The
evolution temperature (548–563 K) was higher than the gas evolution temperature from the crystalline films. The far from center
positioned films crystallized at higher temperature with relatively slower evolution of the gases.
Authors:C. Li, C. Wang, X. Liu, Z. Zheng, L. Wang, Q. Zhu, M. Kang, T. Chen, and C. Liu
In terms of pre-safety assessment of a potential site for high-level radioactive wastes disposal in China, the geochemical
behavior of key radionuclides which tend to be released from the repository must be thoroughly investigated. 99Tc is a long-lived fission product with appreciable productivity in nuclear fuel, and Tc (+7) has unlimited solubility in
near-field geochemical environments. In this study, the effects of ionic strength and humic acid on 99TcO4− sorption and diffusion in Beishan granite were investigated with through-diffusion and batch sorption experiments. Results
indicated that the effective diffusion coefficients (De) of 99TcO4− in Beishan granite varied from 1.07 × 10−12 to 1.28 × 10−12 m2/s without change with ionic strength, while the distribution coefficients (Kd) negatively correlated with ionic strength of the rock/water system. This study also indicates that there is no evident influence
of humic acid concentration on the diffusion behavior of 99TcO4− in Beishan granite, due to the limited interaction between humic acid and 99TcO4−.