Ram Rai

Equatorial irregularity belt and its movement during a magnetic storm

GEOSTATIONARY satellites are able to monitor amplitude, phase, plane of polarisation (Faraday rotation) and group retardation of radio waves passing through the ionosphere with improved temporal resolution, although some of these parameters were earlier measured using orbiting satellites. An extensive experiment has been conducted on Faraday rotation measurements at a chain of stations covering a latitude region from the magnetic equator to 45°N dip (30°N geog.) in the Indian sub-continent using 140 MHz radio beacons received from ATS-6 satellite1. We report here the first evidence of an irregularity belt and its movement during a magnetic storm.

PREPARATION AND CHARACTERIZATION OF SOLID DISPERSION OF ITRACONAZOLE

The aim of the present study was to improve the dissolution rate and oral bioavailability of a poorly water soluble drug, itraconozole (ITR) by its adsorption on a porous calcium silicate (FLR). The drug w as adsorbed on FLR by adsorption method . solid dispersion of various composition were prepared using Porous Calcium Silicate (FLR), Silicic Acid, Colloidal Silica and Silica Gel (Neutral) (2:1, 1:1, 1:2, 1:3, Physical mixture) . C rystallinity of the drug in the solid dispersion was evaluated by differentia l scanning calorimetry and powder X - ray diffraction analysis. Itraconazole was released at a much higher rate from solid dispersion and physical mixture as compared to that as of it r aconazole faster dissolution was exhibited by solid dispersion containing 1:2 ratios of drug and polymer compared to physical mixture and itraconazole . The increase in dissolution rate of the drug may be due to decrease in crystalinity.

Total electron content at low latitudes

Radio beacon from ATS-6 at 140 MHz was used to measure the changes in the polarization angle (Faraday rotation) at Bombay, Rajkot, Ahmedabad, Udaipur and Patiala during October 1975 to July 1976. In this paper, results of diurnal, seasonal and latitudinal variations in total electron content (TEC) derived from these measurements are reported. The amplitude of diurnal peak is found to be higher at Rajkot, Ahmedabad and Udaipur as compared to that at Patiala or Bombay, indicating that the peak of Appleton anomaly in the latitudinal variation of TEC was close to the latitude of Ahmedabad. The diurnal maximum of TEC occurs around the same time during summer and winter months. The peak electron content shows a semiannual variation at all the stations with large values in equinoxes as compared to winter and summer. The TEC at Bombay shows a seasonal anamoly with high values in winter as compared to summer. The paper describes the development of latitudinal anomaly with the time of the day for different seasons. This anomaly is maximum during 1000 to 1800 LT and is located between 12° and 14° N (dip latitude) in summer and equinoxes and at about 10°N in winter.

Occurrence and Diversity of Soil Mycoflora in Some Selected Brassica Growing Agricultural Fields of Dehradun District of Uttarak hand Himalaya

Soil is an oligotrophic medium for fungal growth. F ungi are important component in soil microbiota. Depending on soil depth and nutrient co nditions, the fungal biomass exceeds that of bacteria in almost every soil except rhizosphere so il which is dominated by bacteria. Filamentous fungi in soil degrade organic matter and help in so il aggregation. Some produce substances similar to humic substances and some are capable of forming ectotrophic associations on the root system of forest trees and help in mobilisation of soil phosp horus and nitrogen into plants. Many fungi are biological control agents for plant pathogens and i nsect pests. In Uttarakhand especially in Dehradun District very scanty information is availa ble regarding soil inhabiting microfungi of Agricultural fields. Therefore some agricultural la nds growing Brassica crop were selected to study the composition, dominance and diversity of microfu ngi and physico-chemical properties of the soil inhabited by these fungi. Five agricultural lands viz. Rajawala (RAJ), Bahada rpur(BAH), Bhauwala (BHAU), Telpura (TLP) and Sudhowala (SUDH) were selected. Each land was s urveyed repeatedly to collect soil samples. Soil samples were collected from different depths v0-5 cm, 5-10 cm, 10-15 cm, 15-20 cm. and 2025 cm and composite samples were made for each agri cultural land. For all soil samples examined, pH varied from 6.42± 1.24 to 7.84±1.56; moisture content varied from8.42±1.68 to 10.84±2.16; organic contents varie d from 1.55 to 3.00 and texture varied from sandy to sandy loam. Micronutrients were very high in all the soil samples. A total of 383 colonies of microfungi belonging to 11 genera and 26 species we re isolated. Anamorphic fungi (Deuteromycota) were dominant and represented by 9 genera and 22 sp ecies followed by Zygomycota represented by 2 genera and 4 species. Fungal populations were alw ays highest in surface soil and decreased along with soil-depth. Maximum fungal species were isolat ed from BAH at the depth of 0-10 cm followed by RAZ, whereas the minimum fungal species were iso lated from BHAU, TPR and SUDH at the depth of 15-20 cm. Of the total 26 species recorded , 8 species were of common occurrence, 9 species of frequent, 8 species of moderate and 1 species of rare occurrence respectively. Shanon- Wiever index of species diversity was highe st (2.734) in BAH followed by RAZ (2.686), TLP (2.583) and SUDH (2.553) while it was lowest for BH AU (2.540). Simpson index of diversity also showed identical trends. Highest similarity (84.2%) was observed between RAJ and BAH and lowest (55.6%) between RAJ and TLP. The present investigation will be helpful in docume ntation and conservation as well as in controlling soil borne pathogens. Further, it certainly opens u p a new horizon for the researchers in this interesting and challenging field of soil microfung al biodiversity.

Synthesis and characterization of Ag–Co–Ni nanowires

This work provides an electrodeposition‐based methodology for synthesizing multicomponent nanowires containing Ag, Co and Ni atoms. Nanowire morphology was obtained by using an anodic alumina membrane with cylindrical pores of ∼200‐nm diameter. Structural, compositional and magnetic characterization revealed that the as‐synthesized nanowires adopted a core–shell microstructure. The core (axial region) contained pure Ag phase volumes with a plate‐like morphology oriented perpendicular to the nanowire axis. The shell (peripheral region) contained pure Ag nanoparticles along with superparamagnetic Co and Ni rich clusters.