Modeling energy and agriculture interactions—I: A rural energy systems model

Since many of the factors related to rural energy systems are gradually being quantified, there is a need to construct a model that integrates a number of these factors simultaneously in a consistent framework. Therefore, a general linear programming model is developed to capture energy and agricultural interactions existing in the rural areas of developing countries. Energy used for agriculture includes fertilizers, irrigation, and mechanization. Several technological choices of each of the above are considered and so are several crop commodities, several types of livestock, and farmers of different income groups along with their assets, i.e. land holdings, livestock, etc. The by-products of agriculture, i.e. biomass, such as crop residues, animal dung, wood, etc., can be used to generate energy. On the demand side the use of them for feed, fuel, and fertilizer must be considered. Thus, the household sector (which is the largest user of noncommercial energy), as well as the rural industries sector, is intimately related to the agriculture sector. Twelve different energy sources and several conversion technologies, such as biogas, charcoal kilns, alcohol distilleries, etc., are considered. The model is applicable to low-income, biomass-scarce developing countries. However, different types of countries will require different approximations, and their needs for detailing some aspects or other may vary. The model is suitable for policy purposes because it considers several income groups separately and considers how different changes affect each of them.     

Some spectral response characteristics of ZnTe thin films

Zinc telluride thin films have been grown at room temperature and higher temperature substrates by thermal evaporation technique in a vacuum of 10^-6 torr. A main peak in the photocurrent is observed at 781 nm (1.58 eV) with two lower amplitude peaks on the lower wavelength side and one on higher wavelength side. The evaluated thermal activation energy is found to correspond well with the main spectral peak. From these studies it can be inferred that temperatures up to 453 K is still in the extrinsic conductivity region of the studied ZnTe thin films. The paper was presented at the 6th Asian Thermophysical Properties Conference (6th ATPC), held at Gauhati University, during 8–11 October 2001.     

Aggregate input-output models of neuronal populations

An extraordinary amount of electrophysiological data has been collected from various brain nuclei to help us understand how neural activity in one region influences another region. In this paper, we exploit the point process modeling (PPM) framework and describe a method for constructing aggregate input-output (IO) stochastic models that predict spiking activity of a population of neurons in the "output" region as a function of the spiking activity of a population of neurons in the "input" region. We first build PPMs of each output neuron as a function of all input neurons, and then cluster the output neurons using the model parameters. Output neurons that lie within the same cluster have the same functional dependence on the input neurons. We first applied our method to simulated data, and successfully uncovered the predetermined relationship between the two regions. We then applied our method to experimental data to understand the input-output relationship between motor cortical neurons and 1) somatosensory and 2) premotor cortical neurons during a behavioral task. Our aggregate IO models highlighted interesting physiological dependences including relative effects of inhibition/excitation from input neurons and extrinsic factors on output neurons.     

Ambient pressure dried TEOS-based silica aerogels: good absorbents of organic liquids

The experimental work has been carried out to study the absorption–desorption properties of the hydrophobic silica aerogel for the application of oil spill cleanup. Aerogels were synthesized by sol–gel route prior to ambient pressure drying, by keeping TEOS:MeOH:Acidic H₂O:NH₄F:NH₄OH:HMDZ molar ratio constant at 1:16.5:0.81:0.62:0.63:0.41, respectively. The absorption of organic liquids by as-prepared aerogels has been carried out by adding the aerogel samples in organic liquid, viz. three alkanes: hexane, heptane, octane; the aromatic compounds: benzene, toluene, xylene; the alcohols: methanol, ethanol, propanol, and the three oils: petrol, diesel, and kerosene until it is totally wetted. It was observed that surface-modified TEOS-based aerogel absorbed the organic liquids and oils by nearly 12 times its own mass. After absorption, desorption time of liquids from the aerogel at various temperatures, i.e., at 30, 60, 80, and 100 °C was measured. The 50% volume shrinkage of the aerogel in case of oils and 20% in case of organic liquid was observed, after total desorption of liquids. No significant change in hydrophobicity of the aerogel was observed and it can be reused two times.     

Comparative amino acid and fatty acid compositions of edible gums kondagogu (Cochlospermum gossypium) and karaya (Sterculia urens)

Gum karaya and gum kondagogu are the two important commercial tree gums of India. The amino acids and fatty acid profiles of gum kondagogu and gum karaya were investigated by preparing their corresponding N-O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) derivatives for amino acids and direct trans-esterification of methyl esters for fatty acids and their subsequent analysis by a GC–MS method. The amino acids, such as, alanine, valine, methionine, tyrosine and tryptophan, were not detected in gum karaya as they were in gum kondagogu. Interestingly, the aspartic acid content (72.8 ± 3.45 μg/g) of gum kondagogu was higher than that of gum karaya (64.2 ± 2.44 μg/g). The ratios of saturated to unsaturated fatty acid in gum kondagogu and gum karaya were found to be 5:1, and 6.6:1, respectively. Among the unsaturated fatty acids, linoleic acid (1.8 ± 0.12 μg/g) and γ-linolenic acid (0.8 ± 0.05 μg/g) were detected only in gum kondagogu. Arachidic acid was not detected in gum karaya. Additionally, the presence of linoleic acid and γ-linolenic acid in gum kondagogu reinforces its nutritional value.     

Optimization and surface modification of silk fabric using DBD air plasma for improving wicking properties

It is necessary to study the suitable effect of plasma parameters, such as exposure time and applied voltage on the wicking properties of silk fabrics. Wicking property of silk fabric has been improved by using air dielectric barrier discharge plasma treatment. The plasma treatment has been utilized to modify the surface properties of silk fabrics. Untreated and plasma-treated fabrics have been characterized by contact angle Goniometer, wicking test, Wet-out time, scanning electron microscope, Attenuated Total Reflection Fourier Transforms Infrared spectrometer (ATR-FTIR) and dye uptake test. The ATR-FTIR characterization shows that the hydroxyl functional group has been increased after plasma treatment of silk fabric. The experimental results of wicking rate and Wet-out time of the plasma-treated silk fabrics have shown significant improvement in hydrophilic properties that could be confirmed by contact angle measurement which is close to 0°. The tensile strength of untreated and plasma-treated fabrics has been measured to confirm the enhanced surface property.