Analysis of diffraction gratings by using an edge element method

Typically the grating problem is formulated for TE and TM polarizations by using, respectively, the electric and magnetic fields aligned with the grating wall and perpendicular to the plane of incidence, and this leads to a one-field-component problem. For some grating profiles such as metallic gratings with a triangular profile, the prediction of TM polarization by using a standard finite-element method experiences a slower convergence rate, and this reduces the accuracy of the computed results and also introduces a numerical polarization effect. This discrepancy cannot be seen as a simple numerical issue, since it has been observed for different types of numerical methods based on the classical formulation. Hence an alternative formulation is proposed, where the grating problem is modeled by taking the electric field as unknown for TM polarization. The application of this idea to both TE and TM polarizations leads to a two-field-component problem. The purpose of the paper is to propose an edge finite-element method to solve this wave problem. A comparison of the results of the proposed formulation and the classical formulation shows improvement and robustness in the new approach. © 2005 Optical Society of America

Improved polymer solar cell performance by engineering of cathode interface

By engineering the interface between the intermediate photoactive layer and the cathode aluminum (Al) electrode, through the introduction of ultra-thin layers of various materials, in a standard\ud bulk heterojunction (BHJ) polymer solar cell (PSC) fabricated of regioregular poly(3-hexylthiophene)(rr-P3HT) and phenyl-C61-butyric acid methyl ester (PCBM), the power conversion efficiency (PCE) has\ud been effectively improved. The devices fabricated using individual single interlayer of bathocuproine (BCP), lithium fluoride (LiF) and Buckminster fullerene C60 have shown optimal efficiencies of ∼2.40%, ∼3.21% and ∼1.92% respectively. Further improvement of the photovoltaic efficiency was achieved by introducing a composite bilayer made of LiF in combination with BCP as well as with C60 at the BHJ/cathode interface. The best results were obtained by interposing a 9 nm of C60 interlayer in combination with a 0.9 nm\ud thick LiF layer, with the PCE of the PV cells being effectively increased up to 3.94% which represents an improvement of 23% as compared to the standard device with LiF interlayer alone. The photocurrent density (Jsc) versus voltage (V ) characteristic curves shows that the increase of the efficiency is essentially\ud due to an increase in Jsc. Moreover, all the sets of devices fabricated using various interlayers over a certain range of thickness exhibit an optimum PCE that is inversely proportional to the series resistance of the PV cells. We presume that interposing a C60/LiF layer at the interface could repair the poor contact at\ud the electron acceptor/cathode interface and improve the charge career extraction from the BHJ

Effect of grain boundaries on the interfacial behaviour of graphene-polyethylene nanocomposite

Aim of this article was to investigate the effect of grain boundaries on the interfacial properties of bi-crystalline graphene/polyethylene based nanocomposites. Molecular dynamics based atomistic simulations were performed in conjunction with the reactive force field parameters to capture atomic interactions within graphene and polyethylene atoms, whereas non-bonded interactions were considered for the interfacial properties. Atoms at the higher energy state in bi-crystalline graphene helps in improving the interaction at the nanocomposite interphase. Geometrical imperfections such as wrinkles and ripples helps the bi-crystalline graphene in increasing the number of adhesion points between the nanofiller and matrix, which eventually improves the strength and toughness of nanocomposite. These outcomes will help in opening new opportunities for defective nanofillers in the development of nanocomposites for future applications

Comprehensive Analysis on the Relationship between Risk Habits and Oral Cancer Outcomes

Lifestyle risk factors are crucial in the development and growth of oral cancer, which is yet an important issue for the public. Research offers a via evaluation of the connection between oral cancer results, such as cancer survival, recurring, and therapeutic reactions, and a variety of risk behaviors, involving eating betel nuts, drinking alcohol, using tobacco, and practicing poor dental hygiene. Through patient surveys and medical record monitoring, a comprehensive data collection was conducted on around 250 patients, 170 of whom were male and 80 of whom were female. The result based on the Analysis of variance (ANOVA) test demonstrates that, compared to individuals with independent risk behaviors, those with numerous risk habits had much worse predictions. Particularly, drinking alcohol and smoking cigarettes were linked to a lower chance of surviving and sooner resurgence. Furthermore, it was shown that behavioral treatments aimed at improving dental hygiene and quitting risky habits increased the effectiveness of therapy. The research emphasizes the significance of focused global healthcare initiatives to reduce risk factors and enhance results for patients.

The effect of hydrogen nanobubbles on the morphology of gold–gelatin bionanocomposite films and their optical properties

Gold–gelatin bionanocomposite films are prepared by the reduction of gold ions by sodium borohydride in an aqueous solution. It is shown that both the solution and the films on glass substrates contain entrapped hydrogen micro- and nanobubbles with diameters in the range of 200 nm–3 μm. The optical properties of gold nanoparticles in the presence of gelatin and hydrogen nanobubbles are measured and simulated by using the discrete dipole approximation method. The composite films having micro- and nanobubble inclusions have been found to be very stable. The calculated localized surface plasmon resonance band is found in agreement with the experimental band position only when the presence of hydrogen bubbles around the gold nanoparticles is taken into account. The different morphological features engendered by the presence of the bubbles in the film (gelatin receptacles for the nanoparticles, gelatin hemispheres raised by the bubbles under the surface, cavities on the surface of the film, etc) are described in detail and considered for potential applications. This work is highly relevant to the new and exciting topic of nanobubbles on surfaces and interfaces

(Invited) Nano Composite Platforms: Synthesis and Biological Applications Including Cancer Diagnosis

Nanometal-polymer composite films are hybrid materials with inorganic nanoparticles immobilized and uniformly dispersed into a polymer matrix. Nanoparticles such as gold and silver, used to enhance the optical properties of the polymers, are called `optically effective additives` as they lead to new functionalities of the polymer based materials. Au (Ag)-polymer and copolymer composite films are suitable for applications such as waveguides, color filters, thermo-chromic materials etc. The strong plasmon band of Au and Ag nanoparticles (Localized Surface Plasmon Resonance) in the visible spectrum, that originates from the excitation of plasmons by the incident light, makes noble metal-polymer nanocomposites particularly adequate for sensing and biosensing applications. Furthermore, association of Au and Ag nanoparticles of various shapes with poly(dimethylsiloxane) (PDMS), allows the use of nanocomposite materials for microfluidic biosensing as well. In this presentation, we will talk about the in-situ synthesis of Au-PDMS and Ag-PDMS nanocomposites both at the macroscale and inside the channel of a microfluidic chip. The in-situ synthesis of nanoparticles involves the reduction of gold ions in a gold precursor solution by the curing agent of the polymer. The kinetics of the reaction has been investigated and the effect of annealing temperature on the morphology of nanoparticles has been studied by using imaging and spectroscopic methods. The nanocomposite has been successfully used for sensing of antibody-antigen interactions, allowing the detection of various important proteins. Nanocomposies of metals integrated into other polymers such as PMMA, PVA, and PS have been synthesized as well by using UV, microwave and thermal reduction methods. The effect of the particle`s shape on the properties of nanocomposites and their sensing abilities has also been studied by synthesizing nanostar particles and integrating them into microchannels. Because of the biocompatibility and non-toxicity of gold and silver nanoparticles, their nanocomposites can be used for plasmonic detection of biological entities in cancer research. </jats:p