Petrology and physical conditions of metamorphism of calcsilicate rocks from low- to high-grade transition area, Dharmapuri District, Tamil Nadu

Calc-silicate rocks comprising quartz, plagioclase, diopside, sphene, scapolite, grossularite-andradite and wollastonite occur as lensoid enclaves within the greasy migmatitic and charnockitic gneisses of the Archaean amphibolite- to granulite-facies transition zone in Dharmapuri district, Tamil Nadu. The calc-silicate rocks are characterized by the absence of K-feldspar and primary calcite, presence of large modal quartz and plagioclase and formation of secondary garnet and zoisite rims around scapolite and wollastonite. The mineral distributions suggest compositional layering. The chemical composition and mineralogy of the calc-silicate rocks indicate that they were derived from impure silica-rich calcareous sediments whose composition is similar to that of pelite-limestone mixtures. From the mineral assemblages the temperature, pressure and fluid composition during metamorphism were estimated. The observed mineral reaction sequences require a range of X sub CO2 values demonstrating that an initially CO2-rich metamorphic fluid evolved with time towards considerably more H2O-rich compositions. These variations in fluid composition suggest that there were sources of water-rich fluids external to the calc-silicate rocks and that mixing of these fluids with those of calc-silicate rocks was important in controlling fluid composition in calc-silicate rocks and some adjacent rock types as well

Brillouin Scattering Studies of La_{0.77}Ca_{0.23}MnO_3 Across Metal-Insulator Transition

Temperature-dependent Brillouin scattering studies have been carried out on La_{0.77}Ca_{0.23}MnO_3 across the paramagnetic insulator - ferromagnetic metal (I-M) transition. The spectra show a surface Rayleigh wave (SRW) and a high velocity pseudo surface acoustic wave (HVPSAW) besides bulk acoustic waves (BAW). The Brillouin shifts associated with SRW and HVPSAW show blue-shifts, where as the frequencies of the BAW decrease below the I-M transition temperature (T_C) of 230 K. These results can be understood based on the temperature dependence of the elastic constants. We also observe a central peak whose width is maximum at T_C.Comment: 7 pages, 8 figure

Effect of Packaging and Storage Temperature on Shelf-Life of Minimally Processed Onion (Allium cepa L.)

Minimally processed onion is a ready-to-use onion product offering the consumer a fully usable commodity, without much change to freshness of the produce. Effect of packaging and storage temperature on shelf-life in minimally processed onion was studied. Packaging and temperature play an important role in determining shelf-life in minimally processed onion. Onion pieces approx. 8-10mm thick were cut with a plain, sharp knife and subjected to dip-treatment with the firming agent, calcium lactate (2%), for 5 minutes. The samples were surface-dried and packaged in polypropylene bags of size 250 X 125mm, of variable thicknesses (25, 50 or 75μm) and stored at low temperatures and high RH:8±1°C and 83±2% RH; 10±1°C and 82±2% RH; and, 12±1°C and 80±2% RH. It was found that onion cv. Arka Sona sliced with a plain, sharp knife, pre-treated with 2% calcium lactate, surface-dried and packaged in polypropylene bags sized 250X125mm (50μm thick), and stored at 8+1°C and 83±2% RH retained freshness and nutritive value, were microbially safe and acceptable, with a shelf-life of 14 days at storage

Dyeing of silk using Madhuca longifolia as natural dye source

The dried leaves of Madhuca longifolia has been evaluated for their potential as a source for natural dyeing of silk. Dye has been extracted under optimum conditions such as extraction pH (10), time (60 min) and temperature (95̊°C). The extracted dye has been applied on the silk fabrics and a range of shades are obtained using different methods with or without using mordants. It is found that mordants have a significant effect on the color of dyed silk fabrics. The dyed samples have been evaluated for color measurements and standard wash, light and rub fastness tests. The extracted dye is also tested for some of the eco-parameters using atomic absorption spectrophotometry and GC/MS. The test results are compared with set standards to determine the eco-friendliness of natural dye. Their concentrations are found to be lower than the stipulated limits. The dyed samples are also tested for antimicrobial activity against Gram-positive and Gram-negative bacteria. The dyed silk fabrics show acceptable fastness properties and are found to possess antibacterial activity. The results show that Madhuca longifolia leaves are promising as a natural colorant, which would, in turn, pave the way for the discovery of a new range of environment-friendly dyes for textile materials

Backscatter Inversion in Spherically Asymmetric Ionosphere

It is Well Known that Various Diurnal and Morphological Features of the Ionosphere Reveal Substantial Departures from the Normally Simplified Assumption of Spherical Symmetry at Certain Times of the Day or at Certain Geographic Locations. a Radio Ray Passing through Such an Ionosphere Must Bear Information About its Horizontal Gradients. the Leading Edge of a Backscatter Ionogram is Formed by Obliquely Propagated Radio Rays of Minimum Time Delay and Hence is Useful in Deducing Information About the Ionospheric Horizontal Gradients. in This Regard, the Ionospheric Electron Density Distribution is Modeled by a Locally Quasi‐parabolic Layer with Six Parameters. This Six‐parameter Space is Known as the \u27ion state.\u27 Our Object is to Seek the \u27best\u27 Ion state in the Sense that the Corresponding Mean Square Error in Group Delay is a Minimum. a Computer Program Has Been Written to Carry Out the Specified Procedure. a Number of Sample Calculations Are Presented and Discussed. Copyright 1979 by the American Geophysical Union

Isolation and cellular fatty acid profile analyzation of two marine bioluminescent bacteria

192-195Two luminescent bacterial strains KOOS1 and KOOS2 isolated from surface mucus of Octopus sp. collected from Andaman were identified by their cellular fatty acid composition analyzation with the help of Microbial Identification system (MIDI). SIM indexes obtained for these isolated strains were 0.772 (KOOS1) and 0.754 (KOOS2) respectively and were identified as Photobacterium damselae and Vibrio fischeri. Major fatty acids found in Photobacterium damselae were Saturated: Dodecanoic acid (C12:0), Tetradecanoic acid (C14:0), Pentadecanoic acid (C15:0), Hexadecanoic acid (C16:0), Heptadecanoic acid (C17:0) and Octadecanoic acid (C18:0); and Unsaturated: 3-hydroxy-9-methyl decanoic acid (C11:0iso 3OH), 3-hydroxydodecanoic(C12:0 3OH), C16:1ω5c, Oleic acid (C18:1ω9c) and C18:1ω5c.In Vibrio fischeri Saturated: C12:0, Tridecanoic acid (C13:0), C15:0, C16:0, C17:0 and C18:0; and Unsaturated: C11:0iso 3OH,2-hydroxydodecanoic (C12:0 2OH), C12:03OH, C13:0iso, C14:0iso, C15:0iso, C15:0anteiso, C16:0iso, C17:0iso, C16:1ω5c, C15:0iso3OH, C17:1 ω8c and C17:1ω6c were found. Cyclopropane acids have not been detected in both Photobacterium damselae and Vibrio fischeri

Health seeking behavior acceptability of available health facilities and knowledge about tuberculosis in a tribal area

A study was undertaken among the tribals living in Buttayagudem Mandal consisting of 53 villages in West Godavari district of Andhra Pradesh to study their health seeking behaviour, acceptability of available health facilities and knowledge about tuberculosis. Information was also obtained on their practices to get relief from illness and type of health facilities used. In all, 429 households belonging to 34 villages were selected at random and the heads of these households or the next responsible persons were interviewed. A total of 189 (44%) had heard of tuberculosis and of these, 72 (38%) attributed it to tubercle bacilli. A majority of the tribals were in favour of modern medicine and accepted the available health facilities

No Eigenvalue in Finite Quantum Electrodynamics

We re-examine Quantum Electrodynamics (QED) with massless electron as a finite quantum field theory as advocated by Gell-Mann-Low, Baker-Johnson, Adler, Jackiw and others. We analyze the Dyson-Schwinger equation satisfied by the massless electron in finite QED and conclude that the theory admits no nontrivial eigenvalue for the fine structure constant.Comment: 13 pages, Late

Influence of lattice distortion on the Curie temperature and spin-phonon coupling in LaMn0.5_{0.5}Co0.5_{0.5}O3_{3}

Two distinct ferromagnetic phases of LaMn$_{0.5}$Co$_{0.5}$O$_{3}$ having monoclinic structure with distinct physical properties have been studied. The ferromagnetic ordering temperature $\textit{T}_{c}$ is found to be different for both the phases. The origin of such contrasting characteristics is assigned to the changes in the distance(s) and angle(s) between Mn - O - Co resulting from distortions observed from neutron diffraction studies. Investigations on the temperature dependent Raman spectroscopy provide evidence for such structural characteristics, which affects the exchange interaction. The difference in B-site ordering which is evident from the neutron diffraction is also responsible for the difference in $\textit{T}_{c}$. Raman scattering suggests the presence of spin-phonon coupling for both the phases around the $\textit{T}_{c}$. Electrical transport properties of both the phases have been investigated based on the lattice distortion.Comment: 9 figure

Brillouin scattering studies in Fe3_3O4_4 across the Verwey transition

Brillouin scattering studies have been carried out on high quality single crystals of Fe$_3$O$_4$ with [100] and [110] faces in the temperature range of 300 to 30 K. The room temperature spectrum shows a surface Rayleigh wave (SRW) mode at 8 GHz and a longitudinal acoustic (LA) mode at 60 GHz. The SRW mode frequency shows a minimum at the Verwey transition temperature $T_V$ of 123 K. The softening of the SRW mode frequency from about 250 K to $T_V$ can be quantitatively understood as a result of a decrease in the shear elastic constant C$_{44}$, arising from the coupling of shear strain to charge fluctuations. On the other hand, the LA mode frequency does not show any significant change around $T_V$, but shows a large change in its intensity. The latter shows a maximum at around 120 K in the cooling run and at 165 K in the heating run, exhibiting a large hysteresis of 45 K. This significant change in intensity may be related to the presence of stress-induced ordering of Fe$^{3+}$ and Fe$^{2+}$ at the octahedral sites, as well as to stress-induced domain wall motion.Comment: 14 pages, 3 figures, accepted in Physical Review B 200