Vertical hetero-structures made from stacked monolayers of transition metal dichalcogenides (TMDC) are promising candidates for next-generation optoelectronic and thermoelectric devices. Identification of optimal layered materials for these applications requires the calculation of several physical properties, including electronic band structure and thermal transport coefficients. However, exhaustive screening of the material structure space using ab initio calculations is currently outside the bounds of existing computational resources. Furthermore, the functional form of how the physical properties relate to the structure is unknown, making gradient-based optimization unsuitable. Here, we present a model based on the Bayesian optimization technique to optimize layered TMDC hetero-structures, performing a minimal number of structure calculations. We use the electronic band gap and thermoelectric figure of merit as representative physical properties for optimization. The electronic band structure calculations were performed within the Materials Project framework, while thermoelectric properties were computed with BoltzTraP. With high probability, the Bayesian optimization process is able to discover the optimal hetero-structure after evaluation of only ∼20% of all possible 3-layered structures. In addition, we have used a Gaussian regression model to predict not only the band gap but also the valence band maximum and conduction band minimum energies as a function of the momentum.

We reconstruct centennial scale quantitative changes in surface seawater temperature (SST), evaporation-precipitation (from Mg/Ca and δ18O of surface dwelling planktic foraminifera), productivity (from relative abundance of Globigerina bulloides), carbon burial (from %CaCO3 and organic carbon [%Corg]) and dissolved oxygen at sediment-water interface, covering the entire Holocene, from a core collected from the eastern Arabian Sea. From the multi-proxy record, we define the timing, consequences and possible causes of the mid-Holocene climate transition (MHCT). A distinct shift in evaporation-precipitation (E-P) is observed at 6.4 ka, accompanied by a net cooling of SST. The shift in SST and E-P is synchronous with a change in surface productivity. A concurrent decrease is also noted in both the planktic foraminiferal abundance and coarse sediment fraction. A shift in carbon burial, as inferred from both the %CaCO3 and %Corg, coincides with a change in surface productivity. A simultaneous decrease in dissolved oxygen at the sediment-water interface, suggests that changes affected both the surface and subsurface water. A similar concomitant change is also observed in other cores from the Arabian Sea as well as terrestrial records, suggesting a widespread regional MHCT. The MHCT coincides with decreasing low-latitude summer insolation, perturbations in total solar intensity and an increase in atmospheric CO2.

Silver nanowire-based contacts represent one of the major new directions in transparent contacts for opto-electronic devices with the added advantage that they can have Indium-Tin-Oxide-like properties at substantially reduced processing temperatures and without the use of vacuum-based processing. However, nanowires alone often do not adhere well to the substrate or other film interfaces; even after a relatively high-temperature anneal and unencapsulated nanowires show environmental degradation at high temperature and humidity. Here we report on the development of ZnO/Ag-nanowire composites that have sheet resistance below 10 Ω/sq and >90% transmittance from a solution-based process with process temperatures below 200 °C. These films have significant applications potential in photovoltaics and displays.

Y2O3:Eu3+ nanophosphor was synthesized by flame spray pyrolysis (FSP) from urea added nitrate based liquid precursor. In this study, urea serves as fuel and subsequently provides additional heat in the flame zone during the synthesis of phosphor particles. The end product shows cubic phase Y2O3:Eu3+ nanophosphor successfully prepared by FSP without heat treatment. The influence of synthesis conditions such as different mol of urea and nitrate source materials in aqueous solution, and doping concentration on luminescent properties, were investigated. The characteristics of nanophosphor such as crystallinity and morphology under various experiments of conditions were carried out by x-ray diffraction (XRD) and field emission-scanning electron microscopy (FE-SEM). The particle size of product was found to be in the range of 20–30 nm from transmission electron microscopy (TEM). In photoluminescence (PL) properties, Y2O3:Eu3+ nanophosphor emitted red light with a peak wavelength of 609 nm when excited with 398 nm wavelength photons.

Monodispersed ceria coated silica particles were prepared by a new type of ceria precursor. The ceria precursor was synthesized by alkoxide method, which employs ethanol as solvent. The synthesized particles were characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). It was found that well-crystalline ceria coatings were deposited on the surface of the silica particles without post-heat treatment. In addition, the coated particles prepared by a new precursor were uniformly dispersed without the formation of hard aggregate as compared to those obtained by conventional method.

Bacterial blight (BB) of rice caused by Xanthomonas oryzae pv oryzae (Xoo) is one of the major constraints to productivity in South-East Asia. The strategy of using major genes, singly or in combination, continues to be the most effective approach for BB management. Currently, more than two dozen genes have been designated but not all the known genes are effective against all the prevalent pathotypes. The challenge, therefore, is to continue to expand the gene pool of effective and potentially durable resistance genes. Wild species constitute an important reservoir of the resistance genes including BB. An accession of Oryza nivara (IRGC 81825) was found to be resistant to all the seven Xoo pathotypes prevalent in northern states of India. Inheritance and mapping of resistance in O. nivara was studied by using F2, BC2F2, BC3F1 and BC3F2 progenies of the cross involving Oryza sativa cv PR114 and the O. nivara acc. 81825 using the most virulent Xoo pathotype. Genetic analysis of the segregating progenies revealed that the BB resistance in O. nivara was conditioned by a single dominant gene. Bulked segregant analysis (BSA) of F2 population using 191 polymorphic SSR markers identified a ∼35 centiMorgans (cM) chromosomal region on 4L, bracketed by RM317 and RM562, to be associated with BB resistance. Screening of BC3F1 and BC2F2 progenies and their genotyping with more than 30 polymorphic SSR markers in the region, covering Bacterial artificial chromosome (BAC) clone OSJNBb0085C12, led to mapping of the resistance gene between the STS markers based on annotated genes LOC_Os04g53060 and LOC_Os04g53120, which is ∼38·4 kb. Since none of the known Xa genes, which are mapped on chromosome 4L, are effective against the Xoo pathotypes tested, the BB resistance gene identified and transferred from O. nivara is novel and is tentatively designated as Xa30(t). Homozygous resistant BC3F3 progenies with smallest introgression region have been identified.

A novel ceramic synthesis technique, flame spray pyrolysis (FSP) was investigated for the production of nanophosphor particles. Among the various types of synthesis technique for phosphors, FSP is a powerful method which is capable of producing particles with good crystallinity and high luminescence efficiency. Red light emitting Eu3+ doped Y2O3 nanophosphor was prepared by FSP from nitrate based liquid precursors with high flame temperature. Flame temperature is an important factor to obtain phosphor particles with dense and spherical shape. Different molar percentage of urea was added into the precursor, addition of urea increases the temperature in the flame zone and promotes the formation of nano-size and spherical shaped particles. The importance of urea in the precursor to obtain well dispersed Y2O3:Eu3+ nanophosphor has been studied. The characteristics of nanophosphor such as crystallinity, morphology and photoluminescence in the presence of different moles of urea in nitrate based aqueous solution were investigated. On varying the overall concentration of the precursor, both the optical properties and crystallinity were investigated. XRD spectra showed as-prepared phosphors were obtained directly as cubic phase Y2O3:Eu3+ nanophosphor with high crystallinity and without any post-heat treatments. Luminescence intensity of nanophosphor increased with the amount of urea till 2 M percentages, further increase in urea concentration was found to reduce the PL intensity. We have developed a continuous single-step fabrication method for nanocrystalline Y2O3:Eu3+ nanophosphor without any post-heat treatments procedure.

The crystalline structure, composition, chemical bonding and thermal stability of HfO2-Al2O3 mixtures deposited on Si using a combinatorial pulsed laser deposition technique were investigated. After deposition some films were annealed at temperatures from 850 to 950 °C for 6 or 12 minutes. Grazing incidence x-ray diffraction investigations were performed to asses the crystallinity and thermal stability of the annealed layers. Measurements of the Al to Hf ratios were performed using energy dispersive x-ray spectroscopy and x-ray photoelectron spectroscopy. From simulations of the x-ray reflectivity and spectroscopic ellipsometry spectra the phase composition and thickness of the films was calculated and then the Al to Hf ratios. Al/Hf values of 1 and 8 were found to be necessary to block the crystallization of the films after anneals at 850 and 950 °C, respectively.

The synthesis of nano-functionalized drug particles or drug particles with nanoscale biodegradable polymeric coatings has wider ranging applications in sustained release drug delivery systems. An important area of application includes delivery of drugs, such as proteins, peptides, and glucocorticoids via the inhalation process. The advantages of this method include, rapid absorption by the body and lack of metabolic degradation effects which is typically by some drugs during oral delivery. Here we discuss the novel pulsed laser and pulsed electron method to synthesize nanoscale biodegradable coatings of poly lactic acid (PLA) onto antiasthmatic drugs. In pulsed laser method a pulsed excimer laser ablates a thin layer of polymer which is deposited onto 1 -5 micron drug particles which are fluidized in the gas chamber. The control of the thickness, conformation and the chemistry of the nanoscale coating process will be discussed in detail. Applications of this methodology to delivery of anti asthamtic drugs and insulin will be discussed. The effect of polymer coating chemistry, molecular weight, hydrophobicity, and thickness on the sustained release characteristics will be discussed. A unique method for depositing the PLA films, pulsed electron beam deposition (PED) was used to deposit the films. This technique was tried done to overcome the difficulties like low absorption co-efficient of UV-laser. Method proved to be promising for producing smooth films and offers a better thickness control of the deposition. The RMS roughness and other morphological characteristics of PED deposited films were superior over the conventional laser ablated films.

Ultra-thin conformal polytetrafluoroethylene (PTFE) films were prepared by a novel physical vapor technique i.e., pulsed electron deposition (PED) technique. Prepared PTFE or Teflon thin films show high degree of conformity on patterned substrates. Under optimized deposition conditions the films exhibit superhydrophobicity. The PED processed films were characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM) micrographs and the surface morphology and the conformal nature of the films were studied. The chemical nature and hydrophobicity were studied by FTIR and contact angle measurements, respectively.

A novel technique was developed to create superhydrophobic polytetrafluoroethylene (PTFE) surface using nanosecond pulse electron deposition (PED) technique. The PTFE or Teflon thin films deposited on silicon substrate showed superhydrophobicity evidenced by the contact angle of 166±2 degrees. The SEM micrographs reveal the clustered growth of the deposited film and two level sub-micron asperities which is corroborated by the AFM. FTIR and contact angle studies were conducted to study the chemical nature and the wetting properties of the films.

The electrical response and interfacial layer characterization of nitrogen doped HfO2 gate dielectric thin films are reported. The films were processed at relatively low temperature (~ 400 0C) by pulsed laser deposition and ultra-violet radiation assisted oxidation technique. Nitrogen incorporation in the hafnia films led to O-N and Hf-Si-O-N bonding in the bulk and at hafnia-Si interface respectively. The nitrogen doped hafnia films exhibited a leakage current density lower than 10E-5 A/sq cm at -1 V and a simulated equivalent oxide thickness of 9.4 Å.

Introduction. Planting time is considered as one of the most important factors for successful strawberry cultivation. Traditionally, under north-Indian plains, strawberry is planted after the second week of October, which results in the availability of fruits for a month or so. With the use of plasticulture techniques, the planting time can be enhanced, which facilitates early and higher production, and enhances availability of the fruit for a longer period. Mulching is the most important cultural practice in strawberry, which influences plant growth, fruit yield and quality. Hence, studies were conducted to determine the influence of planting time and mulching on growth, flowering and fruiting behaviour, yield and quality of strawberry in northern plains of India. Materials and methods. Studies were conducted on ‘Chandler’ strawberry with three planting times (mid-September, mid-October and mid-November) as the main effect and three mulching materials (black polyethylene, clear polyethylene and paddy straw) as the sub-main effect in a split-plot design with three replications. Standard procedures were adopted for making observations on plant growth parameters, flowering and fruiting behaviour, yield and quality parameters under different treatment combinations. Results and discussion. Mid-September planting favoured vigorous growth, enhanced flowering and fruiting, which resulted in the production of the largest fruits and highest yield of the best quality. Among the three different mulch materials, plants mulched with black polyethylene had the best growth, fruit weight, yield and quality compared with those mulched with clear polyethylene or paddy straw mulch. The [planting time × mulching] interaction was also found to be significant for all measured parameters. Conclusion. Our study revealed that, in northern plains of India, to get an early and high yield of the best quality under a micro-irrigation system, Chandler strawberry could be planted in mid-September if mulched with black polyethylene.

To understand the ceria–silica chemical mechanical polishing (CMP) mechanisms, we studied the effect of ceria slurry pH on silica removal and surface morphology. Also, in situ friction force measurements were conducted. After polishing; atomic force microscopy, x-ray photoelectron spectroscopy, and scanning electron microscopy were used to quantify the extent of the particle–substrate interaction during CMP. Our results indicate the silica removal by ceria slurries is strongly pH dependent, with the maximum occurring near the isoelectric point of the ceria slurry.

The effect of nano-size silica abrasives in chemical mechanical polishing (CMP) of copper is studied in order to reduce mechanical stresses during polishing, which may minimize defects such as surface scratches, copper peeling, dishing and erosion. In order to achieve low stress polishing of copper while maintaining removal rate efficiency, the formation of chemically modified surface layer, which can be mechanically removed by small size and low hardness abrasives, is critical. Complexing agents play an important role in the formation of a removable surface layer in the presence of the oxidizer, which is responsible for oxide formation, and the inhibitor, which passivates the surface. A new removal mechanism is proposed by correlating results of surface roughness after polishing with removal and etch rates. The effects of large silica and alumina abrasives, ranging from 200-1000 nm in diameter, are also studied to compare the different removal mechanisms.

In chemical mechanical polishing (CMP), it is critical to understand dynamic contact at the pad-particles-wafer interface for desired CMP performance. The dynamic contact is dependent on process variables (platen velocity and down pressure) and particle characteristics (size and concentration), which in turn affect friction force. In this study, we have characterized the dynamic contact at the pad-particles-wafer interface as a function of platen velocity and down pressure. In situ lateral friction force measurements were carried out for silica slurry / sapphire wafer system in order to investigate the dynamic contact during polishing. As solids loading increases, the slope in the friction force vs. platen velocity curve changes from a negative to a positive value. Friction force increases with down pressure for different solids loading conditions. Consequently, friction force is determined as a function of down pressure and platen velocity, validating a dynamic contact mechanism during CMP.