Science Vision

112-117

Authors: S. Rai and A.L. Fanai

The spectroscopic properties of Ho3+ in SiO2-TiO2 were investigated using optical absorption and fluorescence studies. The intensities of the electric dipole transitions of Ho3+ in the SiO2-TiO2 doped glasses were calculated from the absorption spectra in the visible region. From the experimental values of the oscillator strengths and calculated matrix elements, the Judd-Ofelt intensity parameters were calculated by least square analysis. The fluorescence spectral distribution of Ho3+ has been recorded using 370nm excitation source. The emission bands observed near blue and green regions were assigned as 5G5, 5G6→5I8, 5F3→5I8 and 5F4, 5S2 →5I8 radiative transitions.

122-127

Authors: H. Lalruatsanga

In P. wallichii, the flowers are cleistogamous, enclosed by a thin membranous spathe. The two anthers are borne on a forked filament placed adjoining to the stigmatic lobes. Ontogenetically the two anthers developed separately; because of intercalary growth, it becomes bifid. The archesporial cell comprises of uniseriate rows of cells, the anther wall consists of a very thin epidermis, unilayered endothecium with fibrous thickenings and the tapetum with uni- and binucleate cells. The anther wall development is reduced type, middle layers are absent. The connective tissues also acquire fibrous thickenings. Cytokinesis of microspore mother cell is successive type within a distinct callose wall. Pollen grains are dispersed in dyads with minute and dense granular exine.

133-142

Authors: R.K. Pandey

This article discusses the biology and physics of electrical system of living body that controls all body functions. Electrochemical potentials in the nerve cells are the source of billions of electrical signals, which propagate from all parts of body to the brain via neurotransmitters in the living body whose measurements allow obtaining useful clinical information. The propagation of electrical pulses in the living body is like transmission of pulses in a cable. The living cell membrane offers resistance and capacitance that form a complex net of electrical circuit. The ratio of space constant between cells to the time constant of neural resistance and capacitance define the speed of nerve impulses from one cell to other cell.

145-151

Authors: V. Ralte

Phytochemical screening was performed on leaves and flower extracts of Ipomoea cairica obtained from Aizawl, Mizoram. To analyse the bioactive compounds, Pet. ether, CHCl3 and CH3OH extracts of the selected plants were tested by following standard procedures. The results demonstrated the presence of alkaloids, sterols, flavonoids, reducing sugars, tannins, saponins, terpenoids, anthraquinones, glycosides and phenols. These results were compared with literature values. Indications from the results depicted usefulness of the plant parts in the treatment of some common diseases.

158-168

Authors: J. Lalnunmawia and J. Lalhlimpuii

Mizoram predominantly comprises of Surma Group of rocks which also cover the whole area of the Aizawl city. Sandstones exposed along Durtlang road section in the northern part of the Aizawl city are composed mainly of quartz, mica group of minerals like biotite and muscovite, lithic fragments and feldspar group of minerals like plagioclases, microcline and orthoclase, and other minor detrital components. The classification and provenance studies of sandstones are basically done on the basis of three important major detrital minerals like quartz, feldspar and lithic fragments. On the basis of these three components, the sandstones exposed along Durtlang road section were classified into litharenite and sublitharenite. The sources of the sediments were determined to be of igneous and metamorphic terrains, probably of Himalayan orogen and the Indo-Burmese collision zones.