Authors:M. Pham Thi Huynh, F. Carrot, S. Chu Pham Ngoc, M. Dang Vu, and G. Revel
Irrigation of rice plants with a solution of rare earth elements increases both the production capacity and the resistance to disease. Assuming that the treated plants remain expendable, the different parts of plants, root stalk and grain, were analyzed by instrumental neutron activation analysis (INAA) and by mass spectrometry after plasma excitation (ICP-MS). About 40 elements were determined. The results showed that the contamination remained in the roots and was absent in rice grains. The analytical distribution of different elements in different parts of both treated and non-treated plants has given some information conceming the possible effect of the rare earth treatment. The performances of the two analytical methods have been compared.
Six oligomers of -aminocaproic acid (ACA) from dimer (K2) to heptamer (K7), gamma-irradiated in an oxygen-free atmosphere, were investigated by the EPR method. The oligomers were synthesized and irradiated with60Co gamma-rays in the dose range from 0 to 6.5 kGy. The formation of –CH2–CONH–CH–CH2– radical was established. The quantitative determinations of total concentrations of spins were carried out. On the basis of the present and earlier results, the competition of the reactions of detachment of hydrogen and of breaking of –CONH– bond is discussed. The particular resistance of amide bond in dimer seems to be confirmed by the measurements of kinetics of radical decay. The mass spectrometry of gamma-unirradiated ACA and ACA oligomers K2-K4 was carried out. The results indicate a minute contribution of ionic processes in the radiolysis of ACA oligomers in solid phase.
The corrosion reactions of two proposed canister materials, pure copper and Ti-Grade 2 alloy, have been investigated in MCC-1P suggested simulated brine solutions. Test temperatures were 90°C, 150°C and 250°C. The corrosion experiments were conducted under the test procedures of ASTM G1-81, but some modifications of postcleaning procedure were proposed in this study. Experimental results showed that Ti-Grade 2, with an extremely low long-term uniform corrosion rate of 0.1 m·y–1 proved to be an excellent corrosion-resistance ability. The corrosive behaviors of Ti-Grade 2 can be correlated with semi-logarithmic rate functions. Copper, on the other hand, appeared unfeasible under brine circumstances owing to its higher uniform corrosion rate. Its related corrosive behavior could be described by linear equations. Temperature effects on corrosive behavior correlated efficiently according to the Arrhenius functions, indicating a negative influence on corrosion rates.
Authors:S. Mestnik, J. Mengatti, W. Nieto, S. Yanagawa, L. Sumiya, C. Silva, and J. Osso
These studies had the purpose of establishing the optimal conditions for the production of123I through the124Te (p, 2n)123I reaction, using the CV-28 Cyclotron (Emax=24 MeV for protons) at IPEN-CNEN/SP. Two different targets (TeO2 and TeO2+2% Al2O3) were irradiated in order to check their physical resistance against beam current (up to 12 A) and length of irradiation (10 min — 2h), and to evaluate the recovery of the radioiodine produced, by a dry distillation process with a high frequency induction furnace. Later on, enriched124TeO2 (96.2%) targets were irradiated, and123I was produced routinely with a production yield of (3. 31±0.07) mCi/Ah, 1.7% of124I at EOB and radiochemically pure.
14C-Propoxur (Baygon®) was synthesized through the reaction of o-isopropoxyphenol with methyl isocyanate –14C. The product was isolated chromatographically on Florisil and crystallized from carbon tetrachloride. The purity and structure were confirmed using infrared spectra, melting point, co-chromatography on Florisil column, and silica-gel G thin layer chromatography. The purity was found to be at least 99%. The rate of absorption and other characteristics of14C-propoxur resistance inAnopheles Stephensi from the south coast ot Iran was investigated. The mortality of strain adults was 100% after a one hour exposure when 1 ppm14C-propoxur was used. Moreover, the mortality was not changed when a lower concentration (5 ppm) was used. On the other hand, the absorbance of14C-propoxur in several strains ofA. Stephensi has been determined. The identity and TLC characteristics of products formed after 1 and 2 hours exposure, respectively, to14C-propoxur have also been investigated.
Authors:E. Yörükoğulları, G. Yılmaz, and S. Dikmen
In this study, the zeolitic tuffs having clinoptilolite obtained from Bigadic region of western of Anatolia, Turkey were investigated
as regards to whether it is possible to be transformed into amorphous phase from them. At first, the zeolite tuffs rich in
clinoptilolite were characterized using XRD, DTA, TG, DSC, and FTIR standard methods. All the samples were heated at 110 °C
for 2 h and then were expanded within 5 min between the temperatures 1200 and 1400 °C. In addition, porosity and density were
determined. The resistance values of all the samples were measured in acidic and basic media. These samples were also analyzed.
As a result of this study, zeolitic tuffs in clinoptilolite were transformed into amorphous phase, and especially in chemical
industry were found convenient.
Authors:C. Santin, M. Jacobi, R. Schuster, and M. Santoso
The hydrogenation of natural rubber (NR), polybutadiene (BR), and styrene-butadiene (SBR) rubbers with different microstructures
was performed by a diimide hydrogenation agent generated in situ by a non-catalytic method [<cite>1</cite>–<cite>3</cite>]. Many properties of the material depend considerably on variables such as degree of hydrogenation and proportions of vinyl
or phenyl units. The mobility of the hydrogenated chain was investigated by differential scanning calorimetry (DSC) and the
results confirm the relationship between the degree of hydrogenation and chain flexibility. The flexibility of a high cis-1,4 BR hydrogenated sample, was significantly changed and a melting point (Tm) was detected after a certain degree of hydrogenation. Thermal stability was investigated by thermogravimetric analysis (TG)
and an increase was found, but, the thermal resistance was influenced by the presence of the byproduct p-toluenesulfinic acid. Oxidation stability was investigated by chemiluminescence analysis and it improved with hydrogenation.
Composite ion-exchange resins were prepared by coating copper-ferrocyanide (CFC) and hydrous manganese oxide (HMO) powders
on polyurethane (PU) foam. Polyvinyl acetate/Acetone was used as a binder. The foam was loaded with about five times its weight
with CFC and HMO powders. The distribution coefficients of CFC-PU foam and HMO-PU foam for cesium and strontium respectively
were estimated. Under similar conditions the HMO-PU foam showed higher capacity as well as better kinetics for removal of
strontium than CFC-PU foam for Cs. The pilot plant scale studies were conducted using a mixed composite ion-exchange resin
bed. About 1000 bed volumes could be passed before attaining a DF of 10 from an initial value of 60–80. The spent resin was
digested in alkaline KMnO4 and the digested liquid was fixed in cement matrix. The matrices were characterized with respect to compressive strength
and leach resistance.
Authors:Ivone Sato, Luiz Pereira, Marcos Scapin, Marycel Cotrim, Cristiano Mucsi, Jesualdo Rossi, and Luis Martinez
Brazilian nuclear power reactor (PWR type) use, as nuclear fuel, sintered UO2 pellets with Zircaloy cladding. The cladding material has to present high mechanical strength and corrosion resistance, which
are related to the material chemical composition and microstructural characteristics. Zircaloy machining scraps were remelted
using VAR process, resulting in a billet, and its elemental composition was determined. The major elements Zr, Sn, Fe, Cr
and Ni were determined by EDXRFS; Hf and contaminants were determined by WDXRFS. The chemical analysis did not show changes
in the alloy elemental composition, except for Fe and Cr, which their out-off content can be attributed to contamination from
steel scraps. The found Cu contamination may be related to the contact of the melted Zircaloy droplets with copper crucible.
The billet microstructure was evaluated using optical and scanning electron microscopy and showed the typical zirconium alloy
microstructures (needle and plates) resulting from the high cooling rate and thermal gradients, present during the solidification.
We present the water uptake ability of cowpea (Vigna unguliculata Walp)which has been regarded as one of the most drought resistant species amongthe pulse crops. It has been suggested that in the lower part of the stem,parenchymatous tissue for storing water has been developed for the functionof drought resistance. We confirmed that in this tissue, water amount washigh compared to the other stems by neutron radiography. Then the water uptakemanner was measured by positron emitting tracer imaging system (PETIS) using 18F labeled water produced by a cyclotron. Comparing the water uptakemanner of cowpea plant with that of common bean, cowpea plant was found tomaintain high water uptake activity after drying treatment, suggesting thehigh drought resistant character.