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Rice-paddy agriculture is widely expanding, particularly in Asia. Rice-paddy fields are stagnated with water and insecticides are applied to control pests. Expansion of agriculture and pesticide are known drivers of declining amphibian populations globally. Yet, several amphibians persist in such temporary wetlands. How amphibians persist in this landscape matrix is not clearly understood. We document amphibian diversity in rice-paddy fields in south India and examine trophic interactions of the two most abundant species. From 60 rice paddy fields, we recorded six species of anurans among which, Minervarya caperata and Microhyla ornata were most abundant. The stomach contents of 57 individuals of the two species were extracted. They consumed prey items belonging to eight orders and 56 taxonomically distinct units dominated by Diptera and Hymenoptera: Formicidae. Although individuals of M. ornata were smaller in body size compared to M. caperata, both species consumed a similar number of arthropods. The dietary niche breadth of M. caperata was wider than M. ornata and the diets of the two species did not overlap greatly. We discuss our findings in the context of prey availability, foraging strategies, and highlight the role of anurans in pest control. [ABSTRACT FROM AUTHOR]

The experiment was conducted to evaluate the nutrient utilization ability of sweet orange (Citrus sinensis L. Osbeck) budded on five rootstocks (viz., Sathgudi, Rangpur lime, Cleopatra mandarin, Troyer citrange, and Trifoliate orange) in Alfisols at the experimental farm of the Citrus Improvement Project, S. V. Agricultural College Farm, Tirupati, Andhra Pradesh, India. Results of the study revealed that all the five rootstocks showed differential behaviors in terms of nutrient absorption from the soil. Rootstocks exhibited significant variation in the leaf content of potassium (K), copper (Cu), manganese (Mn), and boron (B) at all the three stages of sampling. Concentrations of the following key nutrient elements significantly varied: phosphorus (P), calcium (Ca), magnesium (Mg), zinc (Zn), and Cu at stage 1; K, Ca, Mg, Zn, iron (Fe), and Mn at stage 2; and nitrogen (N), P, Zn, Fe, and B at stage 3. The performances of rootstocks in terms of relative nutrient accumulation indices (RNAIs) were in the order of Sathgudi (1.00) > Rangpur lime (0.98) > Cleopatra mandarin (0.96) > Trifoliate orange (0.76) > Troyer citrange (0.69). The present study clearly demonstrated that citrus rootstocks employed had differential nutritional behavior and different abilities to utilize plant nutrient elements. Thus, the findings of the present study and the methodology adopted can help the horticultural breeders and nutritionists choose the best rootstock/scion combination having the desirable traits of nutrient utilization ability and also to plan effective fertilizer schedule programs for achieving greater yields. [ABSTRACT FROM PUBLISHER]

An activation-energy asymptotic theory is developed that predicts autoignition of condensed hydrocarbon fuels in non-premixed flows. Steady, laminar, stagnation-point flow of an oxidizer stream, toward the vaporizing surface of a liquid fuel is considered. The analysis is restricted to the case where the temperature of the oxidizer stream, T2, is greater than the normal boiling point of the liquid fuel. The gas-phase chemical reaction is described by a one-step overall process. The chemical-kinetic rate parameters are the activation temperature, Ta, and the frequency factor, B. A Zel'dovich number, β, is constructed that is proportional to the ratio Ta/T2. The analysis is performed in the asymptotic limit of large values of β. It predicts the value of the Damkohler number, at autoignition. The Damkohler number is defined as the ratio of a characteristic flow time to a characteristic chemical reaction time. The flow time is the reciprocal of the strain-rate, and the chemical time depends on the chemical-kinetic rate parameters. To illustrate the application of the results of the analysis, experiments are conducted in the counterflow configuration. Fuels tested are n-heptane, n-octane, n-decane, n-dodecane, n-hexadecane, iso-octane, cyclohexane, methylcyclohexane, o-xylene, JP-10, JP-8, and diesel. The temperature of the oxidizer stream at autoignition is measured for various values of the strain-rate. The strain-rate, and the value of the Damkohler number at autoignition, obtained from the analysis, are used to obtain the chemical-kinetic rate parameters, for the fuels tested here. Critical conditions of extinction of flames burning these liquid fuels are also measured. A key finding of this work is that for the straight-chain alkanes tested here, at a given value of the strain-rate, n-heptane is the most difficult to ignite, followed by n-octane, n-decane, n-dodecane, and n-hexadecane. The order is reversed for extinction; here it is found that flames burning n-heptane and n-octane are the most difficult to extinguish followed by n-decane, n-dodecane, and n-hexadecane. [ABSTRACT FROM AUTHOR]

Experimental, numerical, and analytical studies are carried out to elucidate the mechanisms of inhibition of nonpremixed methane flames by bromotrifluoromethane (CF 3 Br). Experiments are performed in the counterflow configuration. In this configuration the reactants are injected into a mixing layer from two ducts. A fuel stream made up of methane and nitrogen (N 2 ) is injected from one duct, and an oxidizer stream of oxygen and N 2 is injected from the other duct. The inhibitor CF 3 Br is either added to the oxidizer stream or the fuel stream. A key objective of this study is to compare chemical inhibition of methane flames when CF 3 Br is added to the oxidizer stream with that when this inhibitor is added to the fuel stream. Critical conditions of extinction are measured. The concentrations of reactants at the boundaries are so chosen that the values of stoichiometric mixture, ? st , and adiabatic temperature, T st , are the same. Numerical calculations are performed using a detailed chemical-kinetic mechanism. A reduced chemical-kinetic mechanism made up of eight global steps is derived from this detailed mechanism. Rate-ratio asymptotic analysis is carried out using this reduced mechanism. Experimental data, numerical calculations, and results of asymptotic analysis show that CF 3 Br is more effective in inhibiting methane flames when it is added to the oxidizer stream when compared with its effectiveness when it is added to the fuel stream. The elementary reaction H + Br 2 ? HBr + Br plays a central role in the inhibition when CF 3 Br is added to the oxidizer stream. This reaction, however, has negligible influence on critical conditions of extinction when CF 3 Br is added to the fuel stream. [ABSTRACT FROM AUTHOR]

A rate-ratio asymptotic analysis of nonpremixed n -heptane (C 7 H 16 ) flames stabilized in the counterflow configuration is carried out. A reduced chemical-kinetic mechanism made up of three global reactions is employed in the analysis. In the first global step, fuel reacts with radicals to form the intermediate compounds hydrogen (H 2 ) and carbon monoxide (CO). The second and third global steps describe oxidation of these intermediate compounds to water vapor (H 2 O) and carbon dioxide (CO 2 ). The number of moles of radicals, α, that react with one mole of n -heptane in the first global step depends on the principal path of oxidation of the fuel in the detailed mechanism from which the reduced mechanism is deduced. The value of α obtained from different detailed chemical-kinetic mechanisms is not the same. In view of this uncertainty, the present study is focused on obtaining an improved understanding of the influence of α on the critical conditions of extinction. The asymptotic flame structure is presumed to comprise outer transport zones and a thin reaction zone. The outer transport zones are inert. Improvements in the present asymptotic analysis over previous asymptotic analyses are that in the transport zones the Lewis number of reactants and products is not presumed to be equal to unity, and heat losses by radiation are included. The Lewis number of any species i is defined as the ratio of thermal diffusivity to the coefficient of diffusion of species i . All chemical reactions are presumed to take place in the reaction zone. The reaction zone is presumed to be made up of an inner layer and an oxidation layer. The structure of the inner layer is obtained by introducing the approximation that only the first global reaction takes place in this layer. The second and third global reactions are presumed to take place in the oxidation layer. Analysis of the outer transport zones and the reaction zone gives the scalar dissipation rate at extinction χ f,q . For a given value of α, radiative extinction is observed when the scalar dissipation rate, χ f , is decreased below a critical value and diffusive extinction is observed when χ f is increased above a critical value. A flame cannot be stabilized for values of α larger than a critical value. The existence of flammable boundaries is a key finding of the present study. [ABSTRACT FROM AUTHOR]

An experimental and numerical study was performed to characterize the structure of diffusion flames stabilized in the mixing layer formed between counterflowing streams of hydrogen diluted with nitrogen and air diluted with nitrogen. Measurements were made with 15% to 30% hydrogen by volume in the fuel stream. The concentration of the reactants in the counterflowing streams as a function of their velocity at flame extinction was recorded over a wide parametric range. Using a UV Raman scattering system, the profiles of the mass fraction of the species H2, O2, H2O and N2 and the temperature profiles were measured at two conditions, one close to and the other far from the critical conditions of extinction. Numerical calculations using detailed chemistry were performed to predict the flame structure and the results were found to agree well with the measurements. It is found that the chemical-kinetic mechanism employed here can accurately describe the combustion of hydrogen. [ABSTRACT FROM PUBLISHER]

‐The asymptotic structure of counterflow, nonpremixed methane–air flames are analyzed using a reduced four step chemical–kinetic mechanism. The rates of these four steps are related to the rates of elementary reactions appearing in the C1–chain mechanism for oxidation of methane. The outer structure of the flame is the classical Burke–Schumann structure governed by the overall one–step reaction CH4 + 202 1; CO2 + 2H20. The inner structure consists of an inner layer and an oxidation layer. Analysisof theinner layer is similar to that performed previously for premixed, methane–air flames and includes the influence of a number of additional reactions which were neglected in a previous analysis of the structure of diffusion flames. Attempts are made to provide a nearly complete description of the structure of the oxidation layer, by removing a number of assumptions introduced in previous analyses. Solutions are shown in the limit ω 1; ∝ and ω 1; 0, where w is the ratio of the thickness of the fuel consumption layer to the radical nonequilibrium layer. Results are obtained for the quantity Xq which is proportional to the strain rate at extinction, for various levels of dilution of the reactant streams. The values of Xq predicted in the limits ω 1; 0 and ω bracket the value of this quantity calculated from previous detailed numerical integrations. Although, the activation energy characterizing the rate of the elementary reactions is not large. the value of an effective overall activation energy describing the variation of Xf with dilutionof the reactant stream, deduced from this analysis is large and agrees reasonably well with the overall rate parameters deduced from experimental measurements of critical conditions of flame extinction. This observation provides a link between the present analysis and previous large activation energy asymptotic analysis. [ABSTRACT FROM PUBLISHER]

A mixing rule is developed to predict extinction of a diffusion flame burning a multicomponent fuel. The chemical reaction is approximated as a one-step process between each component of the fuel and the oxidizer, and the activation energy characterizing the reaction is presumed to be large. The mixing rule predicts the overall chemical kinetic rate parameters characterizing the gas phase oxidation of the multicomponent fuel, if the rate parameters for its components are known. To test the validity of the predictions, extinction experiments were performed on diffusion flames stabilized above heptane, toluene, methanol, and a number of homogeneous solutions (with different proportions of the components) of these fuels. Experimental and theoretical values for the overall activation energy for the solutions were found to agree to better than 5 percent, and the preexponential factors were found to agree to better than a factor of three. [ABSTRACT FROM PUBLISHER]

The structure of nonpremixed CH4/N02 flames is investigated for various values of the strain rate and pressure. Numerical calculations are performed using a detailed chemical kinetic mechanism comprising 137 reactions among 33 species, a skeletal chemical kinetic mechanism comprising 92 reactions among 25 species and reduced chemical-kinetic mechanism comprising 10 and 7 overall reactions. The skeletal mechanism is derived from the detailed mechanism, and the reduced mechanisms are derived from the skeletal mechanism. Chemical reactions in the flame are found to take place in three regions-a fuel-consumption region, a N03 - consumption region and a product-formation region. In the fuel-consumption region the predominant reactions taking place are those between the fuel and the radicals to form the intermediate compounds H2 and CO. In the N02 - consumption region the predominant reactions are between the N02 and radicals to form the intermediate compounds NO and 02. In the product-formation region the products C02, H20 and N2 are formed from the intermediate species. The radicals are also formed in the product-formation region. The flame structure and critical conditions of extinction calculated using the various mechanisms are found to agree with each other. [ABSTRACT FROM PUBLISHER]

There is a rise in number of people diagnosed with Diabetes Mellitus. The incidence is rising in modern Indian society because of Industrial development and drastically changing lifestyles. Diabetic neuropathies are microvascular disorders that are usually associated with the duration of Diabetes. Among the various forms, the most common is Diabetic Peripheral Neuropathy. The disease if neglected leads to chronic ulcer formation leading to amputations frequently. Hence the aim of this study is to document the early cutaneous changes and create an early awareness in the importance of controlling Diabetes. The study consisted of 205 patients with Type 2 DM. Participant's neuropathy status was determined based on Neuropathy Disability Score and Diabetic Neuropathy Symptom Score. Among the Skin changes documented, the common changes seen were: Peripheral hair loss in 185 (90.2%), Xerosis in 168 (82%), Anhydrosis in 162 (79%), Plantar Fissures in 136 (66.3%), Plantar Ulcer in 80 (39%), common nail changes documented were Onychomycosis in 165 (80.5%) and Onychauxis in 53 (25.8%) patients in relation to the occupation and duration of Diabetes mellitus. In conclusion, it is important to control glycemic levels in the all stages of Diabetes and institute foot care measures to prevent the complications of neuropathy. [ABSTRACT FROM AUTHOR]