Plasmonic Resonances and Their Application to Thin-Film Solar Cell

This chapter furnishes the plasmonic properties of metal nanostructure and its application to thin-film solar cell. Plasmonics is an emerging branch of nanooptics where light metal interaction in subwavelength domain is studied. Metal supports surface plasmon resonance that has tunable signature, which depends on the morphology as well as surrounding media. These plasmonic resonances can be tuned in a broader range of solar spectra by changing several parameters such as size, shape and medium. Moreover, metals show scattering properties that could be utilized to enhance optical path length of photon inside the thin film of solar device. The chapter mainly focusses on the study of plasmonic resonance of smaller- and larger-sized metal nanoparticle using semi-analytical as well as numerical approach. For the estimation of optical properties like extinction spectrum and field profile of larger-sized nanoparticle, finite-difference time-domain (FDTD) method is used. The field distribution in both silver and gold nanoparticle cases has been plotted in ‘on’ resonance condition, which has a broader range of applications

Precursor-Driven Nucleation and Growth Kinetics of Gold Nanostars

Recently, seed-mediated approach has been widely utilized for synthesizing monodisperse gold nanostars well-known for plasmonic and sensing applications. Herein, we report a single step seedless/templateless organic synthesis procedure for the complex 3D gold nanostars with a high degree of size/shape control, involving the complexation of polyvinylpyrrolidone (PVP) in polar solvent <i>N</i>,<i>N</i>-dimethylformamide (DMF) and their reduction of AuCl₄^– ions along with hydrochloric acid (HCl) as an effective mediator. On the basis of the kinetic optical absorption and Fourier transform infrared (FTIR) spectroscopy measurements, a convenient ligand exchange mechanism has been proposed for the first time to the best of our knowledge to understand the evolution of these complex shaped gold nanostructures. The coordination interaction among PVP and DMF as well as PVP–DMF–AuCl₄ has been identified as the major driving factors influencing the temporal evolution of the size/shape-controlled gold nanostars

Parametric Study of Wire-EDM Process in Al-Mg-MoS2 Composite Using NSGA-II and MOPSO Algorithms

Al-Mg-based composite is used in producing a variety of components. To improve the machinability of the composite, MoS2 is added. For characterizing the machining of the Al-Mg-based composite, different wt.% (2, 4, and 6) of MoS2 are added as reinforcement. Wire Electrical Discharge Machining (WEDM) process is performed to analyze the kerf width and surface roughness. Due to the complex nature of the WEDM process, the necessity for its optimization through the use of innovative methods is well-proven in the process of research. Evolutionary algorithms, specifically genetic algorithm based on NSGA-II and Multiple Objective Particle Swarm Optimization (MOPSO), are used for optimizing kerf width and surface roughness. For assessing the impact of current, pulse on time, and gap voltage on kerf width and surface roughness, an analysis of the selected WEDM process parameters is performed. MOPSO takes lesser iterations as compared to NSGA-II in giving nearly the same optimal fronts for achieving low kerf width and surface roughness. The 10–12 A of current, 50–57 µs of pulse on time, and 30–33 V of gap voltage are used for the WEDM process based on the Pareto-optimal solutions and better performance is achieved on the samples. In addition, the supplementary DOE method is applied to determine the relationship between factors affecting a process and the response. The analysis revealed that current has played a major part in the governance of kerf width and surface roughness over pulse on time and gap voltage for Al-Mg-MoS2 composite

Solvent-Adaptable Poly(vinylpyrrolidone) Binding Induced Anisotropic Shape Control of Gold Nanostructures

Conformational changes in the intrinsic chemical structure of the polymer poly­(<i>N</i>-vinyl-2-pyrrolidone) (PVP) in aqueous as well as (in)­organic solvents essentially dictates the novel room temperature seedless synthetic procedure for the reduction of hydro-chloroauric acid (HAuCl₄.3H₂O) leading to the formation of different anisotropic size/shaped gold nanoparticles. The interaction between gold metal ions and PVP at the given specific monomer to metal ratio leads to sequential metal ligand exchange, thereby simultaneously utilizing the mild reducing property as well as distinct structure-directing/capping ability of PVP in different (in)­organic solvents, the synchronized features of which have been carefully explored through NMR and FTIR measurements identifying the foolproof signatures of the polymer coordination interaction for the first time in designing the systematic nucleation and growth/stabilization procedures of anisotropic metal gold nanostructures. Furthermore, the complementary XPS data evaluates the quantitative role of coupled oxygen and nitrogen components of the pyrrolidone ring in the PVP–solvent complex in asserting seedless surface mediation as well as the morphology driven localized surface plasmon suitable for wide range of plasmonic as well as photonic applications

Experimental Investigation and Analysis of Mechanical Properties of Palm fibre reinforced Epoxy composites and Sisal fibre reinforced Polyester composites

The objective of this paper was investigated to evaluate tensile, flexural and Impact properties of Palm fibre reinforced Epoxy composites (PFRP) and compared with Sisal fibre reinforced Polyester composites (SFRP). Untreated chopped Palmyra Palm fruit fibre was used as reinforcement in Epoxy resin matrix and chopped sisal fibre was used as reinforcement in Polyester resin matrix. The chopped palm fibrereinforced composite were prepared in volume fractions (Vf) such as 10 %, 20 % and 30 % of specimens by using Epoxy and the chopped sisalfibre reinforced composite were prepared in volume fractions (Vf) such as 10 %, 20 % and 30 % of specimens by using Polyester. The specimens are tested for their mechanical Properties strictly as per ASTM procedures. Static analysis is performed by FEA based software ANSYS R15 with design constraints as Equivalent stress, Shear stress and deflection.The experimental result and analysis shows that the fibre volume fraction increases the tensile, flexural, Impact strength and modulus of the fibre reinforced composite

Expression of Metallothionein, P53 and Antioxidant Enzymes by Selenium and Vitamin D3 during Diethyl Nitrosamine-Induced Rat Liver Preneoplasia: Effect of selenium on nitrosamine-induced rat liver preneoplasia

Many studies have proved that the dietary micronutrient has an inhibitory effect against experimentally induced rat hepatocarcinogenesis. The present work is an attempt to understand combined effect of selenium (Se) and vitamin D3 (vit D3) on some potential protein expression markers of carcinogenesis, such as metallothionein (MT), P53 and antioxidant levels during diethyl nitrosamine (DEN) induced (200mg/kg in 0.9% NaCl; IP) rat liv er preneoplasia. In a short term regimen combined supplementation of Se and vit D3 at a dose of 8 ppm in water and 0.3 μl/100μl in propylene glycol, respectively, suppressed the formation of DNA comets (28.40%), thereby indicating its non- genotoxicity at this particular dose. Se and vit D3 administration throughout the study reduced relative liver weight. Modular incidence were 22.7% when compared to the carcinogen control. However, treatment with Se and vit D3 showed significant expressions of MT and P53 which studied at four sequential time points. An increased immunopositive of P53 protein (1.3±0.56% p&lt;0.02) was found in Se and vit D3 together treated rat liver with an elevated apoptotic labeling index (A1; p&lt;0.001) as documented by TUNEL assay. The positive results of MT expression at various time intervals suggest that, Se and vit D3 together mediated suppression of MT may be associated with induction of apoptosis. The results thus provide evidence for the first time in support of thepotential role of combined supplementation of Se and vit D3 on induction of P53 apoptosis with concurrent suppression of MT in order to have an understanding. Regardless of the mechanism, based on the results reported in this study, both Se and vit D3 could be considered a potential cancer chemopreventive agents whose effect is presumably based on inhibition of growth of the neoplastic cells by coordinated regulations of different biochemical markers and enzymes studied herein

High-yield synthesis and optical response of gold nanostars

Multipod Au nanoparticles (nanostars) with single crystalline tips were synthesized in extremely high yield through the reduction of HAuCl4 in a concentrated solution of poly(vinylpyrrolidone) (PVP) in N,N-dimethylformamide (DMF), in the presence of preformed Au nanoparticle seeds, but with no need for external energy sources. Nanostar dispersions display a well-defined optical response, which was found (through theoretical modeling) to comprise a main mode confined within the tips and a secondary mode confined in the central body. Calculations of the surface enhanced Raman scattering (SERS) response additionally show that this morphology will be relevant for sensing applications. © IOP Publishing Ltd.Funding from the Spanish Ministerio de Educaci´on y Ciencia is acknowledged in the form of a fellowship (PSK) and Grants MAT2004-02991 and NAN2004-08843-C03/C05.Peer Reviewe