Sodium contents in seven mixtures of biological materials from varying aliquants of wheat flour and oyster tissue were analyzed using the INAA (instrumental neutron activation analysis) method. The samples were activated in the thermal column (TC) of the 1 MW TRIGA reactor at our laboratory. To analyze and compare the measured results, the ratioa of the epithermal neutron flux to the thermal neutron flux was determined in the TC, the rotating rack (RR) and the pneumatic terminal (PT). Due to the negligible interferences of24Mg(n, p)24Na and27Al(n, )24Na to23Na(n, )24Na, the Na results were obtained with 97% accuracy and 99% precision. It is shown that the method is suited for accurately determining Na contents in 12 various biological materials, especially for the samples that are low in Na content. From the cadmium ratio measurements of Au (4.9 eV resonance of198Au) and Sm (8 eV resonance of153Sm), ratios ofae/
0 were determined at 0.0011, 0.052 and 0.053 in the TC, RR and PT activation positions, respectively.
one of the most flammable materials, was treated with various compounds containing
nitrogen, phosphorus, halogens, and boron. For a study of flame retardance
from the standpoint of thermal degradation, the samples were subjected to
thermogravimetry (TG), differential thermal analysis (DTA) and differential
thermogravimetry (DTG) in nitrogen to determine if there were any characteristic
correlations between thermal degradation behaviors and the level of flame
retardance. From the resulting data, kinetic parameters for different stages
of thermal degradation are obtained using the method of Broido. The energies
of activation for the decomposition of samples are found to be from 72 to
109 kJ mol–1. For wood and modified wood,
the char yields are found to increase from 10.2 to 30.2%, LOI from 18 to 36.5,
which indicates that the flame retardance of wood treated with compounds is
improved. The flame retardant mechanism of different compounds has also been
The heat capacities of N-(tert-butoxycarbonyl)-l-phenylalanine (abbreviated to NTBLP in this article), as an important chemical intermediates used to synthesize proteins and polypeptides, were measured by means of a fully automated adiabatic calorimeter over the temperature range from 78 to 350 K. The measured experimental heat capacities were fitted to a polynomial equation as a function of temperature. The thermodynamic functions, HT − H298.15K and ST − S298.15K, were calculated based on the heat capacity polynomial equation in the temperature range of (80–350 K) with an interval of 5 K. The thermal stability of the compound was further studied using TG and DSC analyses; a possible mechanism for thermal decomposition of the compound was suggested.
The present study explores the feasibility of the determination of phosphorus at the extreme trace levels in high-purity silicon by radioreagent method. After silicon dissolution with hydrofluoric and nitric acids and matrix volatilization, 12-molybdophosphoric acid (12-MPA) is formed by the addition of the radioreagent,99MoO
, in nitric acid medium and then extracted into isobutyl acetate. By plotting the phosphorus content against the radioactivity of99Mo in the organic phase, a linear relationship persisting down to 5 ng is obtained. Special effort has been made to the elimination of the unreacted99MoO
reagent and the optimal control of phosphorus blank introduced through the multistage analytical procedure in order to ensure reliable determination of phosphorus at the ppb level.
The prompt k0,H factors for B, N, Si, P, S and Cl were determined relative to the 2223.25 keV gamma-line from the 1H(n,γ) reaction. The measurements were performed at the SNU-KAERI Prompt Gamma Activation Analysis facility, of which the background was greatly reduced recently by upgrading the detection system to a Compton suppressed g-ray spectrometer with a BGO/NaI(Tl) guard detector and by improving the shield geometry. From the measured prompt k0,H factors, the partial γ-ray production cross sections were determined using the latest cross section for H. The measured prompt k0,H factors were tabulated and compared with the other reported data.
Authors:S. Mojumdar, M. Sain, R. Prasad, L. Sun, and J. Venart
There are many thermoanalytical techniques but only several of them such as thermogravimetric analysis (TG), high resolution
thermogravimetric analysis (Hi-Res™ TG), derivative thermogravimetry (DTG), differential thermal analysis (DTA), calorimetry,
differential scanning calorimetry (DSC), modulated differential scanning calorimetry (MDSC), evolved gas analysis (EGA), transient
thermal analysis (TTA) and thermal conductivity (k) have selected to be discussed in this paper. Simultaneous thermal analysis (STA) is ideal for investigating issues such
as the glass transition of modified glasses, binder burnout, dehydration of ceramic materials or decomposition behaviour of
inorganic building materials, also with gas analysis. Selected applications of various thermoanalytical techniques from medicine
to construction have also been discussed in this paper.
Authors:Yoon J. Kim, Mi S. Lim, Su M. Kim, Ki H. Ryu, and Sun H. Choi
Tobacco rattle virus (TRV-K) was first identified in a symptomatic Gladiolus plant cultivated in Korea. We analyzed the TRV-K genome and compared its phylogeny with other TRV isolates. After constructing of a full-length genomic RNA2 strand clone, a complete sequence was generated from several overlapping clones. The cloned genome was 3261 bases in length, identical to TRV-K, and had three open reading frames. TRV-K had the highest sequence identity with the American isolate TRV-ORY. Sequence analysis of the RNA2 genome showed that TRV-K contains an intact 2a, 2b, and 2c coding sequence and an RNA1-related 3′ terminus, which is typical of TRV RNA2. Phylogenetic analysis revealed that TRV-K is in the same cluster as the American isolates and another Korean isolate, TRV-SK; however, it was in a different cluster than the European isolates.
Authors:H.J. Shi, Z.J. Sun, Z.M. Yan, and J.B. Ren
Temperature uniformity and heating rate subjected to radio frequency (RF) heating have major impact on the quality of treated low moisture foods. The objective of this paper was to analyse the influence of electrode distance on the heating behaviour of RF on condition that the sample shape, size, and location between the electrodes were defined. Considering peanut butter (PB) and wheat flour (WF) as sample food, a 3D computer simulation model was developed using COMSOL, which was experimentally validated by a RF machine (27.12 MHz, 6 kW). Specifically, the electrode distances were selected as 84, 89, 93, 99 and 89, 93, 98, 103 (mm) for RF heating of PB and WF, respectively. Results showed that the simulated results and experimental data agreed well; the temperature-time histories of the RF heating of PB and WF were approximate straight lines; both the temperature uniformity index and the heating rate decreased with the increase of the electrode distance; the heating rate had a negative logarithmic linear relationship with the electrode distance, which was independent of the types, geometry shapes and sizes of low moisture foods.
Authors:M. Yui, Y. Kikawada, T. Oi, T. Honda, D. Sun, and K. Shuai
A brine sample and two deposit samples of a salt lake in China were analyzed for their contents of lanthanoids (Ln's), thorium
and uranium by neutron activation analysis. Five Ln's were determined at sub ppb levels. Th and U contents were at about the
same levels as those of Ln's. The lanthanoid abundance patterns (Ln pattern) of the three samples are similar to each other,
each having a negative slope in the light Ln region. There seems no substantial difference in distribution between the solution
(brine) and solid (deposit) phases among Ln's.
Authors:H. Yang, N. Tan, F. WU, H. Liu, M. Sun, Z. She, and Y. Lin
The uranium(VI) accumulation was studied in detail by using the biomass of mangrove endophytic fungus Fusarium sp.#ZZF51 from the South China Sea. The uranium(VI) biosorption process onto the tested fungus powders was optimized at pH 4.0,
adsorption time 60 min, and uranium(VI) initial concentration 50 mg L−1 with 61.89% of removal efficiency. According to Fourier transform infrared spectra for the tested fungus before and after
loaded with uranium(VI), the results showed that both of hydroxyl and carboxyl groups acted as the important roles in the
adsorption process. In addition, the experimental data were analyzed by using parameter and kinetic models, and it was obtained
that the Langmuir isotherm model and the pseudo-second-order kinetic model provided better correlation with the experimental
data for adsorption of uranium(VI).