The specific surface area of mercuric oxide has been measured by heterogeneous isotope exchange, gas adsorption, air-permeability and microscopic methods. Values obtained by the four methods were compared and explanations given for the observed differences.
Specific surface area of antimony oxide samples, one commercial and the other prepared from antimony trichloride have been measured by heterogeneous isotope exchange, gas adsorption, airpermeability and microscopic methods. Specific surface areas obtained by these four methods for the two samples were compared and the observed differences are explained.
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.
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.
Authors:Y. Xia, J. I. Friese, D. A. Moore, and L. Rao
A solvent extraction method was used to determine the stability constants of Np(V) complexes with fluoride and sulfate in
1.0M NaClO4 from 25 to 60 °C. The distribution ratio of Np(V) between the organic and aqueous phases was found to decrease as the concentrations
of fluoride and sulfate were increased. Stability constants of the 1 : 1 Np(V)-fluoride complexes and the 1 : 1 Np(V)-sulfate
and 1 : 2 Np(V)-sulfate complexes, dominant in the aqueous phase under the experimental conditions, were calculated from the
effect of [F-] and [SO42-] on the distribution ratio. The enthalpy and entropy of complexation were calculated from the stability constants at different
temperatures by using the Van't Hoff equation.
Authors:Y. Rao, R. Yadav, R. Swamy, B. Gopalan, and S. Syamsundar
The two step oxidation of UO2+x and reduction of U3O8 powders observed during Differential Thermal Analysis (DTA) has been exploited to determine their Specific Surface Areas
(SSAs). The results obtained by this method have been compared with the Braunauer, Emmett and Teller (BET) method and are
found to be in good agreement in the SSA range of 2–4 m2/gm in the case of UO2+x obtained from ADU route and 4–8 m2/gm in the case of AUC route. A precision of ±0.1 m2/gm is obtained. The maximum temperature of oxidation and reduction of these oxides are dependent upon their preparative routes
such as Ammonium Diuranate (ADU) and Ammonium Uranyl Carbonate (AUC).
Authors:Y. Chaturvedi, G. Rao, A. Tiwari, B. Duduk, and A. Bertaccini
During recent years, increasing attention has been devoted to the development of field floriculture, particularly for benefit of small farming businesses that produce seedlings of perennial ornamental plants for the domestic market and for export to neighboring countries. Like other segments of agricultural economies, this industry is threatened by plant diseases, including those associated to phytoplasma infection. Phytoplasmas cause diseases in several commercial cut flower and ornamental plant causing serious economic losses all around the world. Therefore, phytoplasma diseases are the major constraints in profitable ornamental plants production and lowers its quantum and quality gaining international importance because of unspecific symptoms, various losses and diverse epidemiology throughout the world. Epidemics of these diseases have compelled withdrawal of many floriculture plant varieties from cultivation such as gladiolus, lily, chrysanthemum and rose. Symptoms of general yellowing and stunting of plants, proliferation of shoots, phyllody, virescence, reduced size of flowers and reddening of leaves were observed in diverse ornamental plants in botanical gardens and various floriculture farms. Knowledge of the diversity of phytoplasmas has been expanded by recent studies as well as the availability of molecular tools for pathogen identification. The diversity of the potential reservoir of disease has been increased with the discovery of new phytoplasmas hosts. Ornamental plant phytoplasmas showed wide geographical distribution. The ‘
. P. asteris’ belonging to 16SrI group is the major group associated with ornamentals worldwide, so far more than 42 ornamental plant species were reported as phytoplasma infected. Basing on the sequences retrieved from GenBank identified phytoplasmas mainly belong to 16SrI, 16SrII, 16SrIII, 16SrV, 16SrVI, 16SrVII, 16SrIX, 16SrX, 16SrXII, 16SrXIII and 16SrXV groups. In this review, detailed information on occurrence, symptomatology, molecular characterization, transmission, taxonomy, genetic diversity and management approaches on phytoplasma infecting ornamental plants have been discussed.
Complexation of neptunium(V) with fluoride in aqueous solutions at elevated temperatures was studied by spectrophotometry
and microcalorimetry. Two successive complexes, NpO2F(aq) and NpO2F2−, were identified by spectrophotometry in the temperature range of 10–70°C. Thermodynamic parameters, including the equilibrium
constants and enthalpy of complexation between Np(V) and fluoride at 10–70°C were determined. Results show that the complexation
of Np(V) with fluoride is endothermic and that the complexation is enhanced by the increase in temperature — a two-fold increase
in the stability constants of NpO2F(aq) and more than five-fold increase in the stability constants of NpO2F2− as the temperature is increased from 10 to 70°C.
Sulfate, one of the inorganic constituents in the groundwater of nuclear waste repository, could affect the migration of radioactive
materials by forming complexes. Spectrophotometric and microcalorimetric titrations were performed to identify the Np(V)/sulfate
complex and determine the equilibrium constants and enthalpy of complexation at 10–70°C.
Results show that the complexation of Np(V) with sulfate is weak but slightly enhanced by the increase in temperature. The
complexation is endothermic and becomes more endothermic with the increase in temperature. The enhanced complexation at elevated
temperatures is due to the increasingly larger entropy of complexation that exceeds the increase in enthalpy, indicating that
the complexation of Np(V) with sulfate is entropy-driven.