Authors:Yeshwant Naik, G. Rama Rao, and V. Venugopal
The separation characteristics of hydrogen-tritium mixtures by gas chromatography at 77 K have been studied using molecular sieve 4A, coated with 5 wt% vanadium in the form of V2O4, as supporting material. The performance of the column was found to be better than that observed on the conventional coated and uncoated molecular sieves in terms of reduced retention times, resolution, nature of the peak and added thermal stability of the stationary phase.
Studies on the individual potentiometric determination of uranium and plutonium in a single aliquot have been initiated recently
in our laboratory. It was required to adapt the reported procedures (for the precise determination of uranium and plutonium
individually when present together in a sample) at various stages to make them suitable for the successive application of
the procedures to the same aliquot. Two alternative schemes are proposed in the present work. In the first, plutonium is determined
by HClO4 oxidation followed by the determination of total uranium and plutonium by Zn(Hg) reduction. In the second, plutonium is determined
by AgO oxidation following the determination of total uranium and plutonium by Zn(Hg) reduction. Amount of uranium is computed
in both cases from the difference of two determinations. Precision for the assay of plutonium and uranium was found to be
±0.25% and ±0.35%, respectively, at milligram levels.
Synergism is observed in the extraction of uranium(VI) by the binary mixture of Aliquat 336 and PC 88A (2-ethylhexylphosphonic acid mono-2-ethylhexyl ester) from 0.5–6M HNO3 solution showing a maximum at 3M. In H2SO4 medium, antagonism at lower acidity and slight synergism at higher acid concentrations have been observed. Synergism occurs in the extraction of Am(III) from nitrate solutions when a mixture of Aliquat 336 and TOPO is used.
The present study deals with the ontogeny, structure and development of Cardiospermum halicacabum fruit and the mode of its dehiscence. The trigonous, pyriform and bladdery capsular fruit of C. halicacabum develops from a 3-celled ovary with one ovule in each cell. The ovary wall is 5 to 7 cell layers thick. The outer epidermis of the ovary wall develops into a single-layered epicarp. The isodiametric cells of developing epicarp contain abundant tanniniferous contents. The 3 or 4 layers thick ground parenchyma of ovary wall constitutes the mesocarp. The thin walled cells of developing mesocarp are found to get apart from each other, as their elongation is meagre, to keep pace with the increment in the circumference of fruit. The tangentially elongated cells of inner epidermis of ovary wall form a single layered endocarp. The endocarpic cells of developing fruit do not exhibit much structural changes, except vacuolation. Due to the disintegration of thin walled parenchyma cells situated throughout the length of the septum and rupture of similar type of cells located in between two lateral vascular bundles, the ripe capsule of C. halicacabum dehisces septicidally.
Volume reduction studies were carried out on low level radioactive plastic wastes containing polyethylene, PVC and neoprene
by melt densification. The optimized temperature for melting of plastics was between 170 and 180 °C. Based on laboratory scale
studies. Plant scale studies were planned and conducted. The volume reduction factors obtained were around 30, which was 6-10
times higher than that of the conventional compaction process. Thermogravimetry and infrared spectroscopy were used to investigate
the thermal and structural properties of the given materials. The effect of the presence of salts like potassium permanganate
and hydrazine sulphate on the thermal properties of the materials was also evaluated. Leaching studies were also performed
on melt-densified specimens in the laboratory. The average leach index was observed to be around 9, which was higher than
the minimum stipulated value.
The spiny capsule of Argemone mexicanadevelops from a unilocular ovary with numerous ovules borne on pariteal placentae. The ovary wall comprises a layer of outer epidermis and inner epidermis each with 12 to 14 layered ground parenchyma or mesoderm in between. The epicarp, which develops from the outer epidermis of the developing pericarp, possesses numerous anomocytic type of stomata, but no trichomes. The deep lyind mesodermal layers from the mesocarp, which embed pericarpic vascular bundles and their tangentially extended ramifications. The thin walled and highly vacuolated mesocarpic cells undergo disorganisation at the maturity of fruit. The tangentially elongated cells of inner epidermis of ovary from the endocarp, which at maturity of the fruit possesses thick walled cells. The cells of placentum of developing fruit contain abundant starch. Due to the contraction of disorganised parenchyma cells, the dried fruit, leaving the marginal veins and persistent stigma, dechisces at its apical region.
Sixty durum wheat genotypes were analysed for protein (gliadin) polymorphism to find out the existing genetic diversity, and to assess its utility for improvement in grain yield along with quality traits. Six different
alleles were found in land races, rust resistance sources and old released varieties, while two in recently released and advance lines. Most of the recently released varieties and advance lines showed γ-45/
alleles, which is the best type for pasta making quality, remaining showed γ-42/
allele, which are not good for pasta making. It is advisable to select for γ-45/
as a bio-chemical marker in the future breeding programmes. The rust resistance sources do not possess γ-45/
alleles, so these lines can be used as donors to introduce disease resistance in the good quality recently released varieties, which are containing γ-45/
alleles. From hierarchical analysis, it was found that landraces, released varieties and rust resistance sources are genetically distinct. The presence of new γ-gliadin patterns are interesting in rust resistance sources and need to be investigated for their role in pasta making as well as overall technological quality of durum wheat.
Authors:V. Bhargava, V. Rao, S. Marathe, S. Sahakundu, and R. Iyer
A radiochemical method is described for the separation of heavier rare earths from the fission of uranium. The method is particularly
suitable for the separation of low yield (10−5%–10−7%), highly asymmetric rare earth fission products viz.179,177Lu,175Yb,173Tm,172,171Er,167Ho and161,160Tb in the neutron induced fission of natural and depleted uranium targets. Additional separation steps have been incorporated
for decontamination from239Np (an activation product) and93-90Y (a high fission-yield product) which show similar chemical behaviour to rare earths. Separation of individual rare earths
is achieved by a cation exchange method performed at 80°C by elution with α-hydroxyisobutyric acid (α-HIBA).
Authors:S. Sahakundu, S. Marathe, V. Rao, V. Bhargava, and R. Iyer
A new method for obtaining radiochemically pure67Cu from highly active fission product solutions is described. The method is based on the solvent extraction of the Cu(II)-diethyldithiocarbamate
complex in n-butyl acetate in the presence of hold-back carriers for Ni, Co, Mn, Mo, rare earths, Cd, Te and Sb, and subsequent
purification steps involving scavengings for Ag, Ba, Sr and Fe followed by an anion-exchange purification step for decontamination
from Te. Copper is finally extracted as the α-benzoin oxime complex in which form it is mounted and counted. The method has
several advantages over other methods in that decontamination is very high and it is sufficiently fast considering the stringent
radiochemical purity achieved. The67Cu separated by this procedure from a one-day-old mixture of fission products arising from 1010 fissions was found to be completely free of any contamination.