Group farming for sustainable aquaculture

Sustainable farming is a critical issue in aquaculture development. The concept is well understood but the issue is that of methodology for implementing it. It is well recognized that fragmented holdings have been a major constraint in the implementation of farming practices by small-scale farmers. In India 80 per cent of the shrimp production comes from small and marginal holdings which follow different systems of production, including the traditional ‘pokkali’ farms of Kerala state, improved traditional farming, and scientific methods. Group farming, which was highly successful in paddy farming, was tested among small-scale shrimp farmers practicing paddy and shrimp farming in rotation in a cluster of ‘pokkali’ fields in Kerala. The model served as an effective extension intervention to educate farmers on sustainability while helping them to improve their farming practices. The farmers, including women, could be equipped with the technology for farming not only shrimp but also finfish, crab and aquaculture feed production by strengthening the farmer–extensionist–researcher–political–administrative linkages. The work was done during 1993–1996 at the Central Marine Fisheries Research Institute, Cochin, India. The study formed a part of the action research project on empowerment of rural communities through extension

QENS and FTIR studies on binding states of benzene molecules adsorbed in zeolite HZSM-5 at room temperature

Fourier-transform infrared (FTIR) spectroscopy and quasi-elastic neutron scattering (QENS) were employed for monitoring of the binding states of benzene molecules, adsorbed in HZSM-5 zeolite at 300 K and for loadings of 0.6 to 7 molecules per unit cell. While the in-plane combination C-C and C-H stretching bands of adsorbed benzene remained una.ected, a splitting was observed in the out-of-plane C-H bending vibrational bands, a feature reported for the transformation of benzene from liquid to solid phase. Also, the intensity ratio of the in-plane C-C stretching band (ν19 of adsorbed benzene at 1479 cm-1 and the bands in the region ) 3100-3035 cm-1 due to fundamentals and combination C-C and C-H stretching vibrations indicated a trend observed typically for a condensed phase of benzene. No shift was observed in the frequency of the above-mentioned IR bands when zeolite samples exchanged with Na+ or Ca2+ were employed. QENS results suggest that the benzene molecules occluded in zeolitic pores (~3 molecules per unit cell) undergo a 6-fold rotation but their translation motion is too slow. Also, a high residence time of 16.5 ps was observed for the benzene entrapped in HZSM-5, compared to a time of ~2.5 ps reported for the liquid and ~19 ps for the solid state of benzene. These results reveal again the compression of the benzene molecules on adsorption in zeolitic pores. It is suggested that the benzene molecules confined in cavities experience a strong intermolecular interaction, giving rise eventually to their clustered state depending on the loading. In the clustered state, benzene molecules are packed with their plane parallel to zeolitic walls and interact with each other through p-electron clouds. No electronic bonding is envisaged between these clusters and the framework or the extra-framework zeolitic sites

A tentative method for the determination of mixed glycerides present in natural fats by estimating the saturated acids present in azelao glycerides obtained by permanganate oxidation in acetone

This article does not have an abstract

Some observations on the chemistry of glycerides-Part I

A critical analysis of the trisaturated glyceride content of fats shows that the natural fats are characterised by definite numerical relationships between the proportions of GS3 experimentally determined and those possible according to chance distribution and that the ratio between these is a specific characteristic of the source

Addition of RDX/HMX on the Ignition Behaviour of Boron-Potassium Nitrate Pyrotechnic Charge

Boron-potassium nitrate (B-KNO3) (25/75) is a well-known pyrotechnic composition whichfinds application as energy-release system for small-calibre rockets and pyrogen igniters forlarger motors. The decomposition of the oxidiser in this composition is endothermic which canbe activated by the addition of high explosives, which decompose exothermically. This paperdescribes the influence of two nitramine explosives, RDX and HMX, on the ignition characteristicsof B-KNO3 composition using thermogravimetry, differential scanning calorimetry, heat andpressure output measurements. Different compositions were prepared by varying the amount ofRDX/HMX from 10 per cent to 50 per cent. Thermal studies on the B-KNO3/high explosivemixtures reveal that these undergo two-stage decomposition. The first stage corresponds to thedecomposition of high explosive and the second stage corresponds to that of the reaction betweenB and KNO3. Kinetic parameters were calculated for both the stages of TG curves using Coats-Redfern and Mac Callum-Tanner methods. Ignition temperature of B-KNO3 decreases on theaddition of RDX/HMX while the onset of RDX or HMX decomposition is not significantly affectedby B-KNO3. The pressure output of B-KNO3 increases on adding RDX/HMX. The heat outputof B-KNO3 is not much affected by the addition of RDX or HMX, even though the heat ofexplosion of RDX and HMX are low. This is due to the reaction between the combustion productsof RDX/HMX and reaction products of B-KNO3 to form more exothermic products like B2O3,releasing extra heat. The flame temperature of the charge increases while the average molecularweight of the products of combustion decreases as the RDX/HMX content increases. Thus, thecharge, on addition of RDX or HMX, produces higher pressure output, maintaining the heatoutput at comparable levels

The oil of Mimusops Elangi (Linn.)

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Three-Dimensional Elastic Compatibility: Twinning in Martensites

We show how the St.Venant compatibility relations for strain in three dimensions lead to twinning for the cubic to tetragonal transition in martensitic materials within a Ginzburg-Landau model in terms of the six components of the symmetric strain tensor. The compatibility constraints generate an anisotropic long-range interaction in the order parameter (deviatoric strain) components. In contrast to two dimensions, the free energy is characterized by a "landscape" of competing metastable states. We find a variety of textures, which result from the elastic frustration due to the effects of compatibility. Our results are also applicable to structural phase transitions in improper ferroelastics such as ferroelectrics and magnetoelastics, where strain acts as a secondary order parameter

The glyceride composition of fats and oils. Part II. The fatty acids and glycerides of Terminalia belerica (Roxb.)

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Intermediate states at structural phase transition: Model with a one-component order parameter coupled to strains

We study a Ginzburg-Landau model of structural phase transition in two dimensions, in which a single order parameter is coupled to the tetragonal and dilational strains. Such elastic coupling terms in the free energy much affect the phase transition behavior particularly near the tricriticality. A characteristic feature is appearance of intermediate states, where the ordered and disordered regions coexist on mesoscopic scales in nearly steady states in a temperature window. The window width increases with increasing the strength of the dilational coupling. It arises from freezing of phase ordering in inhomogeneous strains. No impurity mechanism is involved. We present a simple theory of the intermediate states to produce phase diagrams consistent with simulation results.Comment: 16 pages, 14 figure

Droplet Fluctuations in the Morphology and Kinetics of Martensites

We derive a coarse grained, free-energy functional which describes droplet configurations arising on nucleation of a product crystal within a parent. This involves a new `slow' vacancy mode that lives at the parent-product interface. A mode-coupling theory suggests that a {\it slow} quench from the parent phase produces an equilibrium product, while a {\it fast} quench produces a metastable martensite. In two dimensions, the martensite nuclei grow as `lens-shaped' strips having alternating twin domains, with well-defined front velocities. Several empirically known structural and kinetic relations drop out naturally from our theory.Comment: 4 pages, REVTEX, and 3 .eps figures, compressed and uuencoded, Submitted to Phys. Rev. Let