Showing papers by "Surya Prakash Singh published in 2015"

Conductive silver inks and their applications in printed and flexible electronics

Abstract: Conductive inks have been widely investigated in recent years due to their popularity in printed electronics (PE) and flexible electronics (FE). They comprise specific and unique applications that belong to a whole new level of future technology. In this context, silver is a keenly researched material for its promising application in conductive inks. In printing technology, silver conductive inks have a major role in electronic applications. The emerging integration of different technologies is in the form of silver nanoinks. In recent years, the printed electronics market has been dominated by expensive materials such as gold, platinum, etc., which result in costly and complex instruments. To overcome these drawbacks, silver conductive inks can serve as alternative to the current technology. Presently, printed circuit boards (PCBs) use complex and expensive techniques to fabricate the circuit boards, which in turn increases the overall cost. Solvent-based silver conductive inks are capable of substituting PCB technology while reducing the cost of manufacturing. Due to their stellar reputation, investors are looking forward to applying this technology in printed electronics industries.

Copper conductive inks: synthesis and utilization in flexible electronics

Abstract: Conductive inks are a recent advance in electronics and have promising future applications in flexible electronics and smart applications. In this review we tried to focus on a particular conductive ink that is based on copper nanoparticles. Although extensive research is being done all over the world, a few complications are yet to be perfectly solved. We tried to focus on some of the complications involved in their synthesis and their various applications in the different fields of science. Conductive inks have promising applications in the present trends of science and technology. The main intention behind this review is to list some of the best methods to synthesize copper nanoparticles according to the method of synthesizing them. We chose copper nanoparticle synthesis and the preparation of conductive inks because copper is a very abundant material, possesses high conductivity (after silver), and it has huge potential to replace expensive conductive inks made of silver, graphene, CNTs, etc. The other reason behind focussing on copper is its properties, such as ductility, malleability, thermal dissipation activity, anti-microbial nature, etc. In this review, we have listed some of the best methods of synthesizing copper conductive inks and their usage in various printing techniques. Different methods of sintering for the obtained conductive patterns are also included.

Fuzzy-TISM: A Fuzzy Extension of TISM for Group Decision Making

Abstract: This paper proposes Fuzzy-TISM, approach for group decision making process. The proposed approach is a fuzzy extension of TISM, which is a multi-criteria decision making technique. TISM is an effective technique and is applied widely to identify relationships among different criteria by creating a comprehensive systematic model of directly and indirectly related criteria. The proposed Fuzzy-TISM approach consolidates the process of group preference aggregation in the fuzzy environment, which can be easily applied to any real world group decision making problem. The proposed approach is a novel attempt to integrate TISM approach with the fuzzy sets. The integration of TISM with fuzzy sets provides flexibility to decision makers to further understand the level of influences of one criteria over another, which was earlier present only in the form of binary (0,1) numbers. 0 represents no influence and 1 represents influence. Due to this, the decision maker is left with only the option of saying 0 or 1 irrespective of the level of influence whether it is low, high, or very high. The proposed Fuzzy-TISM approach take care of this issue and gives a wider flexibility to express the level of influence using fuzzy numbers. The working methodology of proposed Fuzzy-TISM is demonstrated through an illustrative example based on vendor selection.

Carbon Dots: The Newest Member of the Carbon Nanomaterials Family

Abstract: Carbon nanomaterials have been extensively researched in the past few years owing to their interesting properties. The massive research efforts resulted in the emergence of carbon dots, which belong to the carbon nanomaterials family. Carbon dots (C-dots) have garnered the attention of researchers mainly due to their convenient availability from organic as well as inorganic materials and also due to the novel properties they exhibit. C-Dots have been said to overcome the era of quantum dots, referring to their levels of toxicity and biocompatibility. In this review, we focus on the discovery of C-dots, their structure and composition, surface passivation to enhance their optical properties, the various synthetic methods used, their applications in different areas, and future perspectives. Emphasis has been given to greener approaches for the synthesis of C-dots in order to make them cost effective as well as to improve their biocompatibility.

Perovskite solar cells based on small molecule hole transporting materials

Abstract: This review gives an overview of the design and development of perovskite solar cells with a main focus on hole transporting materials (HTMs). The recent advances in metal halide perovskite solar cells surprised the traditional photovoltaic community. A key advance was subsequently made by replacing liquid electrolytes with solid state HTMs like spiro-OMeTAD, which not only improve power conversion efficiency but also enhance the cell stability. As a result, many research groups, including our group, have become involved in the synthesis of new HTMs to optimize the photovoltaic properties of perovskite solar cells (PSCs).

Metabolic engineering of medium-chain fatty acid biosynthesis in Nicotiana benthamiana plant leaf lipids

Abstract: Various research groups are investigating the production of oil in non-seed biomass such as leaves. Recently, high levels of oil accumulation have been achieved in plant biomass using a combination of biotechnological approaches which also resulted in significant changes to the fatty acid composition of the leaf oil. In this study, we were interested to determine whether medium-chain fatty acids (MCFA) could be accumulated in leaf oil. MCFA are an ideal feedstock for biodiesel and a range of oleochemical products including lubricants, coatings and detergents. In this study, we explore the synthesis, accumulation and glycerolipid head-group distribution of medium-chain fatty acids (MCFA) in leaves of Nicotiana benthamiana after transient transgenic expression of C12:0-, C14:0- and C16:0-ACP thioesterase genes. We demonstrate that the production of these MCFA in leaf is increased by the co-expression of the WRINKLED1 (WRI1) transcription factor, with the lysophosphatidic acid acyltransferase (LPAAT) from Cocos nucifera being required for the assembly of tri-MCFA TAG species. We also demonstrate that the newly-produced MCFA are incorporated into the triacylglycerol of leaves in which WRI1 + diacylglycerol acyltransferase1 (DGAT1) genes are co-expressed for increased oil accumulation.

Tuning the Photovoltaic Performance of Benzocarbazole-Based Sensitizers for Dye-Sensitized Solar Cells: A Joint Experimental and Theoretical Study of the Influence of π-Spacers

Abstract: Tuning the parameters to enhance the efficiencies of a novel set of metal free sensitizers for dye sensitized solar cells (DSSC) is carried out by varying the π-conjugated spacers that link the donor benzocarbazole to the acceptor cyanoacrylic acid. The molecules are synthesized by different combinations of spacers, namely fluorene-thiophene (BFT), fluorene-furan (BFF), fluorene-phenyl (BFB), and thiophene-phenyl (BTB). The molar extinction coefficients of all the dyes are high which is attributed to benzocarbazole, but it is higher in the dyes in which fluorene is one of the spacers. But interestingly, in the photovoltaic device when the non-fluorene dye BTB is the sensitizer, red-shifted and broader incident photon-to-current efficiency (IPCE) curves are obtained leading to larger short circuit current density, Jsc, almost double when compared to BFB-based cell. The efficiency of the device with this dye as the sensitizer is also the highest in this series. The reasons behind these observations are inve...

Genome-Wide Distribution, Organisation and Functional Characterization of Disease Resistance and Defence Response Genes across Rice Species.

Abstract: The resistance (R) genes and defense response (DR) genes have become very important resources for the development of disease resistant cultivars. In the present investigation, genome-wide identification, expression, phylogenetic and synteny analysis was done for R and DR-genes across three species of rice viz: Oryza sativa ssp indica cv 93-11, Oryza sativa ssp japonica and wild rice species, Oryza brachyantha. We used the in silico approach to identify and map 786 R -genes and 167 DR-genes, 672 R-genes and 142 DR-genes, 251 R-genes and 86 DR-genes in the japonica, indica and O. brachyanth a genomes, respectively. Our analysis showed that 60.5% and 55.6% of the R-genes are tandemly repeated within clusters and distributed over all the rice chromosomes in indica and japonica genomes, respectively. The phylogenetic analysis along with motif distribution shows high degree of conservation of R- and DR-genes in clusters. In silico expression analysis of R-genes and DR-genes showed more than 85% were expressed genes showing corresponding EST matches in the databases. This study gave special emphasis on mechanisms of gene evolution and duplication for R and DR genes across species. Analysis of paralogs across rice species indicated 17% and 4.38% R-genes, 29% and 11.63% DR-genes duplication in indica and Oryza brachyantha, as compared to 20% and 26% duplication of R-genes and DR-genes in japonica respectively. We found that during the course of duplication only 9.5% of R- and DR-genes changed their function and rest of the genes have maintained their identity. Syntenic relationship across three genomes inferred that more orthology is shared between indica and japonica genomes as compared to brachyantha genome. Genome wide identification of R-genes and DR-genes in the rice genome will help in allele mining and functional validation of these genes, and to understand molecular mechanism of disease resistance and their evolution in rice and related species.

Benzimidazole-functionalized ancillary ligands for heteroleptic Ru(II) complexes: synthesis, characterization and dye-sensitized solar cell applications.

Abstract: We have designed and synthesized heteroleptic Ru(II) complexes with a pyridine-benzimidazole ligand (PYBI) for dye-sensitized solar cell (DSSC) applications. The PYBI ligand has major advantages by having the flexibility to introduce appropriate substituents at the four readily available positions through molecular engineering (Chart 1) compared to other ancillary bipyridyl-based ligands. We have substituted position A of the PYBI ligand with either electron-releasing triphenylamine (1) or pyrene (2). We have also introduced 2-hexylthiophene at position A and 3,5-di tert-butyl phenyl group at position B of the PYBI ligand (3). All three heteroleptic Ru(II) complexes have been characterized by mass spectrometry, 1H NMR, and absorption and emission spectroscopies as well as electrochemical methods. The absorption spectrum of complex 3 is red-shifted and the emission spectrum is blue-shifted, when compared to the standard N719 sensitizer. Testing of these newly designed heteroleptic Ru(II) sensitizers has revealed that complex 3 exhibits an efficiency of 7.88% using an I−/I3− redox electrolyte. Experimental observations corroborated by computational calculations have elucidated the high efficiency of complex 3, primarily due to the fact that the substituents at position A are more influential than those at position of B of the PYBI ligand.

Chance constraint-based multi-objective stochastic model for supplier selection

Abstract: Nowadays, every business organization has to execute all decisions in a highly competitive and uncertain scenario for improving its performance. One of such decision that every organization has to undergo is to select best suppliers for timely delivery of good quality parts at minimum cost. Therefore, effective and cost-efficient supplier selection in a stochastic or uncertain scenario helps an organization in achieving its goal. Hence, this paper deals with the supplier selection problem under stochastic environment. In the present work, an attempt is made to model Stochastic Multi-objective Supplier Selection Problem (SMoSSP) applying chance constraint approach. The proposed model considers operational risks involving uncertainties-related supplier’s capacity, product demand, transportation and variable costs and lead time probability distributions. The SMoSSP is solved using non-preemptive goal programming and weighted aggregate function technique. To validate the proposed model data is generated randomly and solved in LINGO 10. Illustrative examples are presented to demonstrate the SMoSSP.

First Study on Phosphonite-Coordinated Ruthenium Sensitizers for Efficient Photocatalytic Hydrogen Evolution.

Abstract: For the first time we report the design and syntheses of phosphonite coordinated ruthenium(II) sensitizers bearing ĈNN ligand and/or terpyridine derivatives carboxylate anchor (GS11, GS12. and GS13) and its application for hydrogen production over Pt–TiO2 system. These heteroleptic complexes exhibit broad metal-to-ligand charge transfer transition band over the whole visible regime extending up to 900 nm. DFT calculations of these complexes show that the HOMO is distributed over the Ru and Cl atom whereas; LUMO is localized on the polypyridile ligand, which are anchored on TiO2 surface. Among the sensitizers tested for photocatalytic hydrogen evolution, GS12 exhibited a maximum turnover number (TON) 8605 (for 8h), which is very high compared to the reference sensitizer (N719) with TON 163 under similar evaluation condition. The dependence of the hydrogen evolution rate at different pH using GS11, GS12, GS13, and DX-1-sensitized Pt–TiO2 has been studied and the maximum H2 production yield was obtained at ...

Shape tunable synthesis of Eu- and Sm-doped ZnO microstructures: a morphological evaluation

Abstract: Facile and low-cost aqueous chemical bath deposition route has been demonstrated to fabricate Eu- and Sm-doped ZnO microstructures. The effect of Eu and Sm ions on the morphology of the ZnO was investigated. The synthesized doped ZnO microstructures were systematically characterized by field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman and Fourier transform infrared spectra. FESEM images depicted the formation of Eu-doped ZnO microsphere and Sm-doped ZnO microplates. XRD spectra showed single crystalline nature of the undoped ZnO microdisks, whereas Eu- and Sm-doped ZnO exhibited the polycrystalline nature. The presence of Eu and Sm ions in the ZnO matrix was confirmed by XPS. This means that all the Eu ions substituted Zn2+ as Eu2+ into the ZnO matrix, whereas most of Sm ions were being in the trivalent state. This was probably due to the segregation of Sm2O3 species on the surface of ZnO microstructures.

Dithiafulvalene functionalized diketopyrrolopyrrole based sensitizers for efficient hydrogen production.

Abstract: We have designed and synthesized two new diketopyrrolopyrrole (DPP) based organic sensitizers (DPPCA and DPPCN) with the dithiafulvalene (DTF) unit as donor and cyanoacrylic acid/malononitrile as acceptor moieties. These dyes showed excellent efficiency of photocatalytic hydrogen production over a Pt–TiO2 composite via solar-induced water splitting. The sensitizers showed broad absorptions over the wide visible regime (500–800 nm). In DPPCN, the malononitrile moiety led to strong intra-molecular charge transfer, as evidenced by red shifted (∼24 nm) absorption maxima with highly enhanced molar absorptivity (108 190 M−1 cm−1). The electrochemical characterization of as-prepared sensitizers confirmed the feasible electron injection from the dye to the TiO2 conduction band (CB) which has been further validated by theoretical studies. In this study, the rate of the photocatalytic activity was found to be dependent on the acceptor part of the dye molecule as DPPCN sensitized Pt–TiO2 (DNPT) exhibited remarkable (1208 μmol) hydrogen evolution yield in comparison to DPPCA sensitized Pt–TiO2 (DAPT) (840 μmol). The rigid DPP core made the sensitizers significantly photo-stable as affirmed by their high hydrogen production efficiency over 80 h of prolonged irradiation. As predicted from density functional theory (DFT) calculations, ground state geometry of the dyes was almost planar, facilitating continuous conjugation throughout the molecule. Time-dependent DFT (TD-DFT) calculations were also carried out to make clear the understanding of charge transfer transition of the dye molecules.

Osmium polypyridyl complexes and their applications to dye-sensitized solar cells.

Abstract: Dye-sensitized solar cells (DSSCs) have received much attention in recent years owing to their efficient conversion of sunlight to electricity. DSSCs became successful alternatives to silicon photovoltaic devices by virtue of their low fabrication costs and easy preparation methods. In DSSCs the dye plays the key role. This review summarizes the applications of osmium sensitizers in DSSCs. We also briefly discussed their synthesis and the effect of various electrolyte systems on device efficiencies.

Flexural Fatigue Analysis of Concrete made with 100% Recycled Concrete Aggregates

Abstract: The paper presents results of an investigation to study the flexural fatigue performance of concrete beams made with 100% Coarse Recycled Concrete Aggregates (RCA). Experimental investigation has been carried out to obtain the flexural fatigue lives of concrete beam specimens of size 100 × 100 × 500 mm at various stress levels under four point flexural fatigue loading. The test data is used to plot the S-N curves and a simple regression analysis is used to propose an equation to estimate the flexural fatigue strength of concrete made with 100% RCA. The flexural fatigue performance of concrete made with 100% RCA has been assessed in terms of its mean and design fatigue lives. Two million cycles fatigue strength/endurance limit has also been estimated and compared with the previous studies available on Natural Aggregates (NA).

Carbon Dots: The Newest Member of the Carbon Nanomaterials Family

Abstract: Carbon nanomaterials have been extensively researched in the past few years owing to their interesting properties. The massive research efforts resulted in the emergence of carbon dots, which belong to the carbon nanomaterials family. Carbon dots (C-dots) have garnered the attention of researchers mainly due to their convenient availability from organic as well as inorganic materials and also due to the novel properties they exhibit. C-Dots have been said to overcome the era of quantum dots, referring to their levels of toxicity and biocompatibility. In this review, we focus on the discovery of C-dots, their structure and composition, surface passivation to enhance their optical properties, the various synthetic methods used, their applications in different areas, and future perspectives. Emphasis has been given to greener approaches for the synthesis of C-dots in order to make them cost effective as well as to improve their biocompatibility.

Tuning of spectral response by co-sensitization in black-dye based dye-sensitized solar cell

Abstract: We have systematically tuned the spectral response of black dye using the co-sensitization technique. In this study we have selected two co-sensitizers coded as AK-01 and U01. The individual overall conversion efficiencies (η) of these co-sensitizers AK-01 and U01 are 6.20% and 6.01%, respectively. A better power conversion efficiency of 10.21% and 10.56% of DSSC was observed when black dye was co-sensitized with AK-01 and U01, respectively, compare to individual single black dye (9.18%). Both AK-01 and U01 co-sensitizers effectively overcome the light absorption of redox electrolyte and improved the dip in the incident-photon-to-current conversion efficiency spectra at 350–420 nm region compared with single black dye. Intensity-modulated photovoltage spectroscopy result shows the longer lifetime of black dye+U01 compared to the black dye which suggest the robust U01 dye sufficiently suppressed the recombination of electrons in the TiO2 with redox electrolyte without any interaction with black dye when co-adsorbed on TiO2.