Embryonic development and hatching of Loligo duvaucelii Orbigny (Loliginidae, Cephalopoda) in the laboratory

The egg masses and adults U common squid Loligo duvaucelii were collected cm the shore seine and from the inteitidal sandy shore at Karwar. The embryonic development and hatching of the squid was observed in the laboratoiy, Each egg mop consisted <^ many egg capsules, each of which, in turn, consisted of 125-150 eggs. Eggs were 2 mm Iraig and 1.75 ram wide and very yolky. The young ones hatched in 5 days measuring 1.83 nun in DML and 3.17 mm in total length including the arms. Mantle width wa^ 1.5S mm. The young ones survived for 5 days in the aquaiium

Seasonal variations of physico-chemical properties of the Great Vedaranyam Swamp, Point Calimere Wildlife Sanctuary, South-east coast of India

The present study was attempted on the physico-chemical variability of the Great Vedaranyam Swamp of the Point Calimere Wildlife Sanctuary, South-east coast of India. Seasonal variation study was carried out to examine level of varying physico-chemical parameters such as temperature, salinity, pH, dissolved oxygen, nitrate, nitrite, electrical conductivity, phosphate, turbidity, total dissolved solids and water depth. The physico-chemical parameters have exhibited considerable seasonal and spatial variations. The qualitative study revealed the present status of the physico-chemical parameters, which would be very helpful for policy makers to take precautionary measures to save the swamp.Key words: Seasonal variations, physico-chemical parameters, Point Calimere Wildlife Sanctuary, pH, salinity, temperature

Signature of a silver phase percolation threshold in microscopically phase separated ternary Ge0.15Se0.85-xAgx (0 <= x <= 0.20) glasses

Temperature modulated Alternating Differential Scanning Calorimetric (ADSC) studies show that Se rich Ge0.15Se0.85-xAgx (0 <= x <= 0.20) glasses are microscopically phase separated, containing Ag2Se phases embedded in a Ge0.15Se0.85 backbone. With increasing silver concentration, Ag2Se phase percolates in the Ge-Se matrix, with a well-defined percolation threshold at x = 0.10. A signature of this percolation transition is shown up in the thermal behavior, as the appearance of two exothermic crystallization peaks. Density, molar volume and micro-hardness measurements, undertaken in the present study, also strongly support this view of percolation transition. The super-ionic conduction observed earlier in these glasses at higher silver proportions, is likely to be connected with the silver phase percolation.Comment: 4 pages, 7 figure

Effect Of Thallium Additive On Heat Capacities Of In-Se Bulk Chalcogenide Glasses

Chalcogenide glasses are promising materials for optoelectronic device applications. Heat capacity of such materials is the essential physical parameter to estimate the energy/data storage capacity. In the present work, the effect of Tl incorporation on heat capacities ΔCpg, ΔCpc and ΔCpm of In10Se90-xTl x (7≤x≤15) and In15Se85-xTlx (2≤x≤10) bulk glasses have been investigated by analyzing the Differential scanning calorimetry (DSC) thermogram plots. Composition dependence of heat capacities of In-Se-Tl glassy systems have been obtained at the peaks of the glass transitions, crystallizations and melting temperatures (Tg, Tc and Tm). It is found that the heat capacities of In10Se90-xTl x and In15Se85-xTlx glasses increases initially with the incorporation of thallium (up to x≤13 and x≤6) and reaches to maximum at x=13 and x=6 respectively beyond which it decreases. This behavior seems to follow the change in network connectivity and rigidity and may be explained with the help of chemical bond theory of solids. Further in these glassy materials, at the average coordination =2.46 (x=13) and = 2.42 (x=6) a sharp slope change is seen in the composition dependence of heat capacity of both the series which is attributed to the rigidity percolation threshold

IR Studies of Impurities in In-Se-Tl Bulk Chalcogenide Glassy System

Chalcogenide glasses with composition In10Se90-xTlx (7≤x≤15) and In15Se85-xTlx (2≤x≤10) are synthesized by melt quenching technique. The FT-IR transmission spectroscopy studies using KBr pellet method in the wavelength range 400-4000 cm-1 has been carried out. The In-Se-Tl glasses studies shows good transparency in the entire spectral range. There is an increase in percentage of transmittance values with increase in the Tl content. In the transmittance curve various absorption bands are seen, which are related to chemical bonds of different extrinsic impurities present in the glassy material. The vibrational properties of the impurities in the powdered samples are measured. Vibrational modes attributed to O-H hydroxyl groups, molecular H2O and carbon impurity atoms were detected in the mid-IR spectra

Magnetic and humidity sensing properties of nanostructured Cu[x]Co[1-x]Fe2O4 synthesized by auto combustion technique

Magnetic nanomaterials (23-43 nm) of Cu$_x$Co$_{1-x}$Fe$_2$O$_4$\ (x = 0.0, 0.5 and 1.0) were synthesized by auto combustion method. The crystallite sizes of these materials were calculated from X-ray diffraction peaks. The band observed in Fourier transform infrared spectrum near 575 cm$^{-1}$ in these samples confirm the presence of ferrite phase. Conductivity measurement shows the thermal hysteresis and demonstrates the knee points at 475$^o$C, 525$^o$C and 500$^o$C for copper ferrite, cobalt ferrite and copper-cobalt mixed ferrite respectively. The hystersis M-H loops for these materials were traced using the Vibrating Sample Magnetometer (VSM) and indicate a significant increase in the saturation magnetization (M$_s$) and remanence (M$_r$) due to the substitution of Cu$^{2+}$ ions in cobalt ferrite, while the intrinsic coercivity (H$_c$) was decreasing. Among these ferrites, copper ferrite exhibits highest sensitivity for humidity.Comment: 12 pages, 7 figure

Nanoindentation studies on waveguides inscribed in chalcogenide glasses using ultrafast laser

Optical straight waveguides are inscribed in GeGaS and GeGaSSb glasses using a high repetition-rate sub-picosecond laser. The mechanical properties of the glasses in the inscribed regions, which have undergone photo induced changes, have been evaluated by using the nanoindentation technique. Results show that the hardness and elastic modulus of the photo-modified glasses are significantly lower as compared to the other locations in the waveguide, which tend to be similar to those of the unexposed areas. The observed mechanical effects are found to correlate well with the optical properties of the waveguides. Further, based on the results, the minimum threshold values of hardness and elastic modulus for the particular propagation mode of the waveguide (single or multi), has been established

Electrical switching studies on Ge-​Te-​Tl chalcogenide glasses: Effect of thallium on the composition dependence of switching voltages

Bulk Ge17Te83-​xTlx glasses (0 ≤ x ≤ 13)​, have been found to exhibit memory type elec. switching. The switching voltages (also known as threshold voltage - Vth) of Ge17Te83-​xTlx glasses decrease with increasing Tl content. The rate of decrease of Vth is greater at lower concns. and Vth falls at a slower rate for higher Tl concns. (x ≥ 6)​. The addn. of Tl to the Ge-​Te network fragments the covalent network and introduces ionic nature to it; the redn. in network connectivity decreases switching voltages with Tl content. The decrease in the glass transition temps. of Ge17Te83-​xTlx glasses with increasing Tl concn. supports the idea of decrease in network connectivity with Tl addn. The more metallic nature of Tl also contributes to the obsd. redn. in the switching voltages of Ge17Te83-​xTlx glasses with Tl content. Further, there is an interesting correlation seen between the threshold voltage Vth and the av. bond energy, as a function of Tl content. The switching voltages of Ge17Te83-​xTlx glasses have been found to decrease with sample thickness almost linearly. The set-​reset studies indicate that the Ge17Te81Tl2 sample can be switched for >10 cycles, whereas other glasses could not be reset beyond 2 switching cycles