Integrated optics � technology and applications

The emergence of optoelectronics and photonics as viable alternatives to electronics in many key areas of engineering relevance is indeed significant. This paper presents a tutorial review of integrated optics � a technologically important development in photonics. Materials, processes, device technology and applications are highlighted.

Analytical Study of Low-Field Diffusive Transport in Highly Asymmetric Bilayer Graphene Nanoribbon

We present a simplified theory of carrier backscattering coefficient in a twofold degenerate asymmetric bilayer graphene nanoribbon (BGN) under the application of a low static electric field. We show that for a highly asymmetric BGN(Delta = gamma), the density of states in the lower subband increases more that of the upper, in which Delta and gamma are the gap and the interlayer coupling constant, respectively. We also demonstrate that under the acoustic phonon scattering regime, the formation of two distinct sets of energy subbands signatures a quantized transmission coefficient as a function of ribbon width and provides an extremely low carrier reflection coefficient for a better Landauer conductance even at room temperature. The well-known result for the ballistic condition has been obtained as a special case of the present analysis under certain limiting conditions which forms an indirect validation of our theoretical formalism.

Computational interrogation of cis-regulatory elements of genes that are common targets of luteotropin and luteolysin in the primate corpus luteum

The rapid recent increase in microarray-based gene expression studies in the corpus luteum (CL) utilizing macaque models gathered increasing volume of data in publically accessible microarray expression databases. Examining gene pathways in different functional states of CL may help to understand the factors that control luteal function and hence human fertility. Co-regulation of genes in microarray experiments may imply common transcriptional regulation by sequence-specific DNA-binding transcriptional factors. We have computationally analyzed the transcription factor binding sites (TFBS) in a previously reported macaque luteal microarray gene set (n = 15) that are common targets of luteotropin (luteinizing hormone (LH) and human chorionic gonadotropin (hCG)) and luteolysin (prostaglandin (PG) F-2 alpha). This in silico approach can reveal transcriptional networks that control these important genes which are representative of the interplay between luteotropic and luteolytic factors in the control of luteal function. Our computational analyses revealed 6 matrix families whose binding sites are significantly over-represented in promoters of these genes. The roles of these factors are discussed, which might help to understand the transcriptional regulatory network in the control of luteal function. These factors might be promising experimental targets for investigation of human luteal insufficiency. (C) 2012 Elsevier B.V. All rights reserved.

A Bottom-Up Approach toward Fabrication of Ultrathin PbS Sheets

Two-dimensional (2D) sheets are currently in the spotlight of nanotechnology owing to high-performance device fabrication possibilities. Building a free-standing quantum sheet with controlled morphology is challenging when large planar geometry and ultranarrow thickness are simultaneously concerned. Coalescence of nanowires into large single-crystalline sheet is a promising approach leading to large, molecularly thick 2D sheets with controlled planar morphology. Here we report on a bottom-up approach to fabricate high-quality ultrathin 2D single crystalline sheets with well-defined rectangular morphology via collective coalescence of PbS nanowires. The ultrathin sheets are strictly rectangular with 1.8 nm thickness, 200-250 nm width, and 3-20 mu m length. The sheets show high electrical conductivity at room and cryogenic temperatures upon device fabrication. Density functional theory (DFT) calculations reveal that a single row of delocalized orbitals of a nanowire is gradually converted into several parallel conduction channels upon sheet formation, which enable superior in-plane carrier conduction.

Structural, EPR, optical and magnetic properties of alpha-Fe2O3 nanoparticles

alpha-Fe2O3 nanoparticles were synthesized by a low temperature solution combustion method. The structural, magnetic and luminescence properties were studied. Powder X-ray diffraction (PXRD) pattern of alpha-Fe2O3 exhibits pure rhombohedral structure. SEM micrographs reveal the dumbbell shaped particles. The EPR spectrum shows an intense resonance signal at g approximate to 5.61 corresponding to isolated Fe3+ ions situated in axially distorted sites, whereas the g approximate to 2.30 is due to Fe3+ ions coupled by exchange interaction. Raman studies show A(1g) (225 cm(-1)) and E-g (293 and 409 cm(-1)) phonon modes. The absorption at 300 nm results from the ligand to metal charge transfer transitions whereas the 540 nm peak is mainly due to the (6)A(1) + (6)A(1) —> T-4(1)(4G) + T-4(1)(4G) excitation of an Fe3+-Fe3+ pair. A prominent TL glow peak was observed at 140 C at heating rate of 5 degrees C s(-1). The trapping parameters namely activation energy (E), frequency factor (s) and order of kinetics (b) were evaluated and discussed. (C) 2012 Elsevier B.V. All rights reserved.

Substrate impact on the growth of InN nanostructures by droplet epitaxy

The substrate effect on InN nanostructures grown by droplet epitaxy has been studied. InN nanostructures were fabricated on Si(111), silicon nitride/Si(111), AlN/Si(111) and Ge(100) substrates by droplet epitaxy using an RF plasma nitrogen source. The morphologies of InN nanostructures were investigated by field emission scanning electron microscopy (FESEM). The chemical bonding configurations of InN nanostructures were examined by x-ray photoelectron spectroscopy (XPS). Photoluminescence spectrum slightly blue shifted compared to the bulk InN, indicating a strong Burstein-Moss effect due to the presence of high electron concentration in the InN dots.

Cyclic nucleotide signaling in intestinal epithelia: getting to the gut of the matter

The intestine is the primary site of nutrient absorption, fluid-ion secretion, and home to trillions of symbiotic microbiota. The high turnover of the intestinal epithelia also renders it susceptible to neoplastic growth. These diverse processes are carefully regulated by an intricate signaling network. Among the myriad molecules involved in intestinal epithelial cell homeostasis are the second messengers, cyclic AMP (cAMP) and cyclic GMP (cGMP). These cyclic nucleotides are synthesized by nucleotidyl cyclases whose activities are regulated by extrinsic and intrinsic cues. Downstream effectors of cAMP and cGMP include protein kinases, cyclic nucleotide gated ion channels, and transcription factors, which modulate key processes such as ion-balance, immune response, and cell proliferation. The web of interaction involving the major signaling pathways of cAMP and cGMP in the intestinal epithelial cell, and possible cross-talk among the pathways, are highlighted in this review. Deregulation of these pathways occurs during infection by pathogens, intestinal inflammation, and cancer. Thus, an appreciation of the importance of cyclic nucleotide signaling in the intestine furthers our understanding of bowel disease, thereby aiding in the development of therapeutic approaches.

GYROSONICS: SIGNATURE ANALYSIS AND REDUCED-ORDER MODELS

In this paper, the authors study the structure of a novel binaural sound with a certain phase and amplitude modulation and the response to this excitation when it is applied to natural rewarding circuit of human brain through auditory neural pathways. This novel excitation, also referred to as gyrosonic excitation in this work, has been found to have interesting effects such as stabilization effects on the left and right hemispheric brain signaling as captured by Galvanic Skin Resistance (GSR) measurements, control of cardiac rhythms (observed from ECG signals), mitigation of psychosomatic syndrome, and mitigation of migraine pain. Experimental data collected from human subjects are presented, and these data are examined to categorize the extent of systems disorder and reinforcement reward due to the gyrosonic stimulus. A multi-path reduced-order model has been developed to analyze the GSR signals. The filtered results are indicative of complicated reinforcing reward patterns due to the gyrosonic stimulation when it is used as a control input for patients with psychosomatic and cardiac disorders.

Structural, iono and thermoluminescence properties of heavy ion (100 MeV Si7+) bombarded Zn2SiO4:Sm3+ nanophosphor

Structural, iono (IL) and thermoluminescence (TL) studies of Zn2SiO4:Sm3+ (1-5 mol%) nanophosphor bombarded with swift heavy ions in the fluence range 3.91 x 10(12)-21.48 x 10(12) cm(-2) have been carried out. The average crystallite sizes for pristine and ion irradiated for 3.91 x 10(12) ions cm(-2) and 21.48 x 10(12) ions cm(-2) were found to be 34, 26 and 20 nm. With increase of ion fluence, the intensity of XRD peaks decreases and FWHM increases. The peak broadening indicates the stress induced point/clusters defects produced due to heavy ion irradiation. IL studies were carried out for different Sm3+ concentrations in Zn2SiO4 by irradiating with ion fluence of 15.62 x 10(12) ions cm(-2). The characteristic emission peaks at similar to 562, 599, 646 and 701 nm were recorded by exciting Si7+ ions in the fluence range 3.91 x 10(12)-21.48 x 10(12) ions cm(-2). These peaks were attributed to (4)G(5/2)-> H-6(5/2) (562 nm), (4)G(5/2)-> H-6(7/2) (599 nm), (4)G(5/2)-> H-6(9/2) (646 nm), and (4)G(5/2)-> H-6(5/2) (701 nm) transitions of Sm3+. The highest emission was recorded at 3 mol% of Sm3+ doped Zn2SiO4. TL studies were carried out for 3 mol% Sm3+ concentration in the fluence range 3.91 x 10(12)-21.48 x 10(12) ions cm(-2). Two U glow peaks at 152 and 223 degrees C were recorded. The kinetic parameters (E, b, and s), were estimated using Chen's peak shape method. Simple glow curve structure (223 degrees C), highly resistive, increase in TL. intensity up to 19.53 x 10(12) ions cm(-2), simple trap distribution makes Zn2SiO4:Sm3+ (3 mol%) phosphor highly useful in radiation dosimetry.

Vorticity moments in four numerical simulations of the 3D Navier-Stokes equations

The issue of intermittency in numerical solutions of the 3D Navier-Stokes equations on a periodic box 0, L](3) is addressed through four sets of numerical simulations that calculate a new set of variables defined by D-m(t) = (pi(-1)(0) Omega(m))(alpha m) for 1 <= m <= infinity where alpha(m) = 2m/(4m - 3) and Omega(m)(t)](2m) = L-3 integral(v) vertical bar omega vertical bar(2m) dV with pi(0) = vL(-2). All four simulations unexpectedly show that the D-m are ordered for m = 1,..., 9 such that Dm+1 < D-m. Moreover, the D-m squeeze together such that Dm+1/D-m NE arrow 1 as m increases. The values of D-1 lie far above the values of the rest of the D-m, giving rise to a suggestion that a depletion of nonlinearity is occurring which could be the cause of Navier-Stokes regularity. The first simulation is of very anisotropic decaying turbulence; the second and third are of decaying isotropic turbulence from random initial conditions and forced isotropic turbulence at fixed Grashof number respectively; the fourth is of very-high-Reynolds-number forced, stationary, isotropic turbulence at up to resolutions of 4096(3).

Multivalent dendritic catalysts in organometallic catalysis

This Review article discusses dendritic organometallic catalysis, originating from catalytic moieties present at the peripheries of a dendrimer. The presence of multiple catalytic moieties at the dendrimer peripheries leads to a positive effect in majority of the homogeneous and heterogeneous catalysis, although a negative or a marginal improvement in the catalytic effect with respect to the corresponding monomeric catalyst were also encountered. A number of recent examples that attempt to rationalize the origin of the dendrimer effect in catalysis are discussed. Further a tabular survey is provided by categorizing the dendritic catalysts and their influence on catalysis. Recent studies on the multivalent dendritic catalysts, wherein varied number of catalytic moieties is installed within a given generation, are utilized to emphasize the role of clustering catalytic moieties at the peripheries of the dendrimers in influencing the catalysis. (C) 2013 Elsevier B. V. All rights reserved.

On Using Nanoporous Alumina Films as Tribological Coating

Anodization of aluminum alloys is a common surface treatment procedure employed for the protection against corrosion. A thin amorphous layer of alumina is formed on the surface of alloy, which seals the alloy surface from the surrounding. This alumina layer being harder than the base aluminum alloy can be useful as a tribological coating. But since this alumina layer is randomly formed with disordered voids and pores, predicting the mechanical properties is difficult. Specific anodizing conditions can be used to form highly ordered anodic nanoporous alumina films 1] on the aluminum alloy surface. These nanoporous alumina layer can be effectively used as a tribological coating, because of the highly ordered controllable geometry and the empty pores which can be used as reservoirs for lubricant.

On the stability of the L-p-norm of the Riemannian curvature tensor

We consider the Riemannian functional defined on the space of Riemannian metrics with unit volume on a closed smooth manifold M where R(g) and dv (g) denote the corresponding Riemannian curvature tensor and volume form and p a (0, a). First we prove that the Riemannian metrics with non-zero constant sectional curvature are strictly stable for for certain values of p. Then we conclude that they are strict local minimizers for for those values of p. Finally generalizing this result we prove that product of space forms of same type and dimension are strict local minimizer for for certain values of p.

Synthesis of Eu3+-activated ZnO superstructures: Photoluminescence, Judd-Ofelt analysis and Sunlight photocatalytic properties

Photoluminescence and photocatalytic properties of Eu-doped ZnO nanoparticles (NPs) were synthesized by facile phyto route. XPS results demonstrated the existence of Eu3+ as dopant into ZnO. Morphologies of the NPs were mainly dependent on Eu3+ and Aloe vera gel. Red shift of energy band gap was due to the creation of intermediate energy states of Eu3+ and oxygen vacancies in the band gap. PL emission of ZnO:Eu3+ (1-11 mol%, 8 ml and 7 mol%, 2-12 ml) exhibit characteristic peaks of D-5(0) -> F-7(2) transitions. From the Judd-Ofelt analysis, intensities of transitions between different.' levels dependent on the symmetry of the local environment of Eu3+ ions. CIE chromaticity co-ordinates confirm reddish emission of the phosphor. Further, NPs exhibit excellent photocatalytic activity for the degradation of Rhodamine B (94%) under Sunlight was attributed to crystallite size, band gap, morphology and oxygen vacancies. In addition, photocatalyst reusability studies were conducted and found that Eu-doped catalyst could be reused several times with negligible decrease in catalytic activity. The present work directs new possibilities to provide some new insights into the design of new phyto synthesized nanophosphors for display devices, photocatalysts with high activity for environmental clean-up and solar energy conversion. (C) 2015 Elsevier B.V. All rights reserved.