Spiking Neural Networks propose to mimic nature’s way of recognizing patterns and making decisions in a fuzzy manner. To develop such networks in hardware, a highly manufacturable technology is required. We have proposed a silicon-based leaky integrate and fire (LIF) neuron, on a sufficiently matured 32 nm CMOS silicon-on-insulator (SOI) technology. The floating body effect of the partially depleted (PD) SOI transistor is used to store “holes” generated by impact ionization in the floating body, which performs the “integrate” function. Recombination or equivalent hole loss mimics the “leak” functions. The “hole” storage reduces the source barrier to increase the transistor current. Upon reaching a threshold current level, an external circuit records a “firing” event and resets the SOI MOSFET by draining all the stored holes. In terms of application, the neuron is able to show classification problems with reasonable accuracy. We looked at the effect of scaling experimentally. Channel length scaling reduces voltage for impact ionization and enables sharper impact ionization producing significant designability of the neuron. A circuit equivalence is also demonstrated to understand the dynamics qualitatively. Three distinct regimes are observed during integration based on different hole leakage mechanism.

Cosmopolites sordidus (Germar), commonly known as banana corm weevil, is an important economic pest in Asia that can cause severe yield loss depending upon the stage at which infestation occurs. In spite of its economic importance, little is known about the population structure of this pest in India. Random amplified polymorphic DNA (RAPD) and amplified fragment length polymorphism (AFLP) were used to characterize the population genetic structure of C. sordidus collected from five hot spot locations in India. Nineteen RAPD primers and five selective AFLP primer combinations generated 147 and 304 amplification products, respectively. UPGMA dendrograms generated with both marker systems failed to reveal populations clustered based on geographic distance, which was confirmed by the Mantel test, which did not show a strong correlation between genetic distance and geographic distance. Values of indices of genetic identity showed that the populations were closely related. Though the gene flow estimate (Nm) between the populations was 0.469, suggesting restricted gene flow, the populations are not genetically distinct. These observations suggest that the range expansion of this banana pest in India has taken place through transport of infested corms and plant material, resulting in genetically close populations that are geographically distinct. These results provide important information on the population structure of this pest in India, which will aid in designing suitable strategies for its control and management, especially with respect to insecticide resistance.

Despite immense efforts, vaccine against visceral leishmaniasis has yet not been developed. Earlier our proteomic study revealed a novel protein, cofactor-independent phoshoglycerate mutase (LdiPGAM), an important enzyme in glucose metabolism, in T helper cells type 1 (Th1) stimulatory region of soluble Leishmania donovani antigen. In this study, LdiPGAM was biochemically and molecularly characterized and evaluated for its immunogenicity and prophylactic efficacy against L. donovani. Immunogenicity of recombinant LdiPGAM (rLdiPGAM) was initially assessed in naïve hamsters immunized with it by analysing mRNA expression of inducible nitric oxide (NO) synthase (iNOS) and other Th1/T helper cells type 2 cytokines, which revealed an upregulation of Th1 cytokines along with iNOS. Immunogenicity of rLdiPGAM was further evaluated in lymphocytes of treated Leishmania-infected hamsters and peripheral blood mononuclear cells of Leishmania patients in clinical remission by various parameters, viz. lymphoproliferation assay and NO production (hamsters and patients) and levels of various cytokines (patients). rLdiPGAM induced remarkable Lymphoproliferative response and NO production in treated Leishmania-infected hamsters as well as in patients and increase in interferon gamma (IFN-γ), interleukin-12 (IL-12p40) responses in Leishmania patients in clinical remission. Vaccination with rLdiPGAM exerted considerable prophylactic efficacy (73%) supported by increase in mRNA expression of iNOS, IFN-γ and IL-12p40 with decrease in transforming growth factor beta and interleukin-10. Above results indicate the importance of rLdiPGAM protein as a potential vaccine candidate against visceral leishmaniasis.

A high gain ZnO nanowire (NW) based photodetector was fabricated, which was sensitive to photoexcitation at or below 370 nm corresponding to the band-edge of ZnO. At an incident wavelength of 370 nm and a bias field of 5 kV/cm, the maximum responsivity was over 105 A/W corresponding to an extremely high photoconductive gain of the order of 106. Through this work we provide experimental evidence of the role of surface and defects in carrier dynamics, resulting in enhanced photoresponse. Using intensity and temperature dependence of the rise and decay rates of photocurrent, we present a detailed analysis that provides an estimate of the activation energies of carrier trapping mechanisms.

High temperature stress at critical growth stages is a major risk factor for wheat in many wheat growing areas globally. Developing weather indices relating to yield reductions in wheat is an urgent requirement for weather-index-based crop insurance. The objectives of the present study were to: (i) identify critical phenological stage(s) for heat stress, (ii) quantify the impact of heat stress at critical growth stage(s) and (iii) work out thresholds of temperature for obtaining above average, average and below average yield of wheat. For achieving these objectives, 11 years’ experimental data for three cultivars (HD-2285, K-8804 and K-9107) under three sowing dates at the Kanpur Centre located in the Indo-Gangetic Plains of Uttar Pradesh, India were used. Among the eight phenological stages, the milk stage (growth stage 73) was identified as most sensitive for high maximum and minimum temperatures to adversely affect yield. The rate of yield reduction with unit increase in maximum and minimum temperatures (°C) was found to be highest in K-8804 and lowest in HD-2285. The optimum ranges of maximum temperature during anthesis, milk, dough and maturity stages are 19·7–21·9, 24·2–26·5, 26·1–28·8 and 29·5–30·8 °C, respectively and those for minimum temperature are 4·3–6·2, 8·3–9·7, 11·5–12·4 and 13·0–15·1 °C, respectively. The thresholds of temperature during critical stages and quantification of heat stress on yield will be of use in devising weather-index-based crop insurance products in wheat and also for breeding temperature-stress-resistant genotypes. This method of devising weather indices in the present study can be used in other crops and regions of the world as an adaptation strategy for climate change.

To quantify the effect of thermal stress and photothermal quotient (PTQ) on yield components, eleven years experimental data of three cultivars (HD-2285, K-8804 and K-9107) under three sowing dates at Kanpur centre were analysed. Number of grains per ear (NG), grain weight per ear (GW) and 1000-grain weight (TG) were identified as prime yield contributing components in HD-2285, K-8804 and K-9107, respectively. GW was highly sensitive to maximum temperature (MXT) while NG was sensitive to minimum temperature (MNT) during jointing (JNT) to anthesis (ATS) as well as the total growing season in all the cultivars. In both HD-2285 and K-8804, optimum MXT and MNT during JNT to ATS are 22.7–24.6 and 7.0–7.9 °C, respectively for obtaining maximum NG. Optimum MXT for GW ranged from 15.8–17.3 °C during tillering (TLR) to JNT stage in K-8804 and K-9107 while it was 20.4 °C during JNT to ATS stage in HD-2285. MXT, MNT and PTQ of 23.6 °C, 9.2 °C and 25 MJ/m2/day/ °C, respectively during JNT to ATS in K-9107 were found optimum for higher TG.

This experiment was conducted to study the long-term effect of soil management treatments on crop yields, sustainability yield indices (SYI) and soil fertility in rainfed semi-arid tropical Alfisol at Hayathnagar Research Farm, Hyderabad, India, during the period 1995 to 2009. The experiment was conducted in a split–split plot design with conventional tillage (CT) and minimum tillage (MT) as main factors, surface application of sorghum stover @ 2 t ha−1 (SS), fresh Gliricidia loppings @ 2 t ha−1 (GL) and ‘no’ residue (NR) as sub-factors and levels of N viz. 0 (N0), 30 (N30), 60 (N60) and 90 (N90) kg N ha−1 as sub–sub factors in a castor–sorghum two-year rotation. On an average, CT maintained 30.4 and 57.0% higher grain yields of sorghum and castor, respectively, over MT. Between two residues, GL performed well in both the crops. The highest yields of sorghum (1425 kg ha−1) and castor (876 kg ha−1) were recorded at 90 kg N ha−1. CT maintained higher SYI of 0.44 compared to MT (0.38) and higher agronomic efficiency (AE) of 13.5 and 6.76 kg grain kg−1 N for sorghum and castor crop, respectively. Use of crop residue as mulch had an advantage in increasing the yield of both the crops with increase in rainfall under CT even without N application (control), probably by making the soil more receptive to water infiltration, better moisture storage and by reducing the evaporative losses. Using response functions, the optimum fertilizer N requirement was also computed for a given set of tillage and residue combinations. The revised optimum fertilizer N doses for sorghum and castor varied from 45 to 56 kg ha−1 and 46 to 74 kg ha−1, respectively, under different tillage and residue combinations and could be recommended depending upon the soil management practices.

The lattice deformation caused by 100 MeV Ti7+ ion irradiation in Si (100) has been studied using X-ray topographic techniques. An important finding is the appearance of a strain field perpendicular to the ion beam direction in the irradiated region well separated from the projected range of implanted ions. This in-plane strain extends in the bulk of the sample and is not merely confined to the surface. The implanted region has been found to experience an out of plane strain which is expected to be tensile in nature.

Hard coatings of TiN and TiB2 have many interesting properties such as high thermal and electrical conductivity, high melting point, good thermodynamic stability and combination of these properties make them an interesting prospect for a wide range of tribological and electronic applications. It is understood that artificial multilayer structures have shown anamolously high hardness and modulii making them likely candidate for future protective coatings. Single layer of TiN, TiB2, and TiB2/TiN microlaminates coatings with varying thickness have been deposited on Si (100) and oxidized Si(111) substrates by in-situ pulsed laser deposition method. These films are deposited at 10 Hz repetition rate of excimer laser (λ = 248 nm). Our preliminary results show that elastic modulii and hardness values of multilayered coatings are superior than monolithic coatings of either of the two constituent materials. The coatings have been characterized by X-ray diffiractometer and AFM techniques. Detailed results have been presented to correlate the effect of microlaminate thickness on the mechanical properties.

Diamond-like carbon (DLC) films have a unique combination of physical and chemical properties such as high hardness, optical transparency, low coefficient of friction and chemical inertness. A pulsed laser (248 nm) has been used to ablate a pyrolytic graphite target to deposit DLC films on Si (100) and 7059 Corning glass substrates. The deposition was carried out in high vacuum (≤ 10−6 Torr) at different temperatures ranging from room temperature to 400°C. The films were characterized by x-ray diffraction, scanning electron microscope, and Raman spectroscopie techniques. The mechanical properties (hardness and Young's modulus) of these films were characterized by nanoindentation. We have found that the films deposited at room temperature and 100°C show the characteristic features of DLC films and have the better hardness and modulus properties compared to the films fabricated at higher temperatures, which transform into amorphous carbon. Correlations of pulsed laser deposition process parameters with the properties of deposited DLC films will be discussed in this paper.

Transition metal of nitrides have many desirable properties for application at elevated temperatures because of extremely high melting point, hardness, high temperature strength, good thermal shock resistance, and high thermal conductivity. We have investigated the thin film coatings of nitrides (titanium nitride, and composite carbon nitride) on various commercial useful substrates by the pulsed laser deposition (PLD) method. The PLD method is unique process for depositing high quality thin films with novel microstructure and properties. The laser parameters: energy density, pulse rate, target/substrate distance and substrate temperature have been optimized to improve the quality of thin films. The mechanical properties of the films have been evaluated at different processed conditions by nanoindentation technique. The films were characterized by X-ray diffraction, scanning electron microscope and FTIR techniques. Optimization of laser deposition parameters to obtain high quality thin films will be discussed in detail.

The inclusion of multiwalled carbon nanotubes in a conjugated polymer matrix results in extensive alterations in the polymer morphology. When the physical state of a substance is changed, heat is either absorbed or liberated but the temperature remains constant. The flexibility of chain molecules arises from rotation round the saturated chain bond moreover the potential energy barriers hindering this rotation. It is not surprising therefore that the flexibility of polymer chains is an important factor in determining their melting points and stability. If the substitution of carbon nanotube is random the primary effect is a decrease in the degree of crystallinity. These microstructures are governed by the balance of interactions between hydrodynamic forces (both viscous and elastic) and the forces working to retain the integrity of the disperse particles, such as interfacial tension or, in the case of solid filler and their mechanical strength. Carbon materials have long been shown to absorb as much as 60 wt% hydrogen due to their large surface areas as well as their high surface to volume ratios. In the present approach conducting polyaniline was doped with metal oxide, such as SnO2, as well as carbon nanotubes. The resulting carbon nanocomposite was made in both gel- and solid-state to study the effect of physical state on hydrogen adsorption and desorption by weight percentage. The morphology formation process and its impact on the rheological properties of complex polymer systems, i.e. polymer blends and composites are being studied. The materials are also compared with regard to their thermal stability using DSC, and further characterized using various techniques such as FTIR. Further experiments are in progress to better understand the nature of the hydrogen storage mechanism.

Cathodoluminescence (CL) technique has been employed to study the optical properties of GaSb after deposition of hydrogenated amorphous silicon (a-Si:H). CL images recorded at various depths in the samples clearly show passivation of extended defects on the surface as well as in the bulk region. The passivation of various recombination centres in the bulk is attributed to formation of hydrogen-impurity complexes by diffusion of hydrogen ions from the plasma. Enhancement in luminescence intensity is seen due to passivation of non-radiative recombination centres. The passivation efficiency is found to improve with increase in a-Si:H deposition temperature.

In the this paper, we have examined the particulate removal efficiency of laser from solid surfaces. The silicon wafers were contaminated with alumina particles with sizes ranging from 0.05 μm to 0.5 μm. The silicon wafers with uniform surface-distribution of alumina particles were subjected to pulsed laser beams at varying conditions. The results obtained have shown that line beam lasers can remove submicron particles more efficiently from solid surfaces. The mechanism responsible for higher particulate removal-efficiency of line beam laser has also been discussed.

Carbon nitride/titanium nitride composite coatings have been deposited on Si (100) and 7059 coming glass by in-situ pulsed laser deposition technique. A pulsed laser (λ = 248 nm) has been used to ablate the both pyrolytic graphite and TiN targets. It has been shown that TiN provides a lattice-matched structural template to seed the growth of carbon nitride crystallites (W. D. Sproul et. al., Appl. Phys. Lett. Vol. 67, 203–205; 1995). This paper describes the same approach to grow carbon nitride composite coatings with varying thicknesses of buffer layer and carbon nitride films at different temperatures and pressures. Our preliminary results show the superior mechanical properties (hardness and modulli). The films have been characterized by Xray diffractometer, SEM, FTIR and Raman spectroscopic techniques.

Cathodoluminescence images of individual pores have been obtained at nanometer resolution in europium-activated yttrium oxide (Y2O3:Eu) (001) thin films, epitaxially grown on LaA1O3 (001) substrates. Comparison with Z-contrast images, obtained simultaneously, directly show the “dead layer” to be about 5 nm thick. This “dead layer” is the origin of the reduced emission efficiency with increasing pore size. Pore sizes were varied by using different substrate temperatures and laser pulse repetition rates during film growth. These films are epitaxially aligned with the substrate, which is always Al terminated.

Thin amorphous films of tantalum oxide were grown on borosilicate crown glass substrates by KrF excimer pulsed laser ablation of a Ta2O5 target, in an oxygen environment. The deposition was performed at a temperature of 250 or 400 °C, while the oxygen pressure was set in the range 5 to 30 mTorr. The optical properties of the tantalum oxide coatings, as evaluated by reflectance/transmittance spectrophotometry, were found to be dependent on the oxygen gas pressure. At a pressure of 5 mTorr, absorbing films were obtained, with extinction coefficients above 10−2 (at λ=633 nm), along with an optical energy band-gap as low as 0.7 eV. At a pressure of 10 mTorr and above, the coatings had refractive indices up to 2.25 (at λ=633 nm), extinction coefficients below 10−4 (for λ>390 nm), and an optical energy band-gap in the range 3.9 to 4.0 eV.