An addition to the endemic Indian radiation of Eutropis: Phylogenetic position of Eutropis dissimilis Hallowell (Squamata: Scincidae)

Skinks of the genus Eutropis represent one of the most widespread and speciose lizard groups in tropical Asia. Numerous recent studies have utilized a variety of genes and methods to reconstruct the phylogeny of these lizards, however these studies have not resolved the placement of one of the widely distributed Eutropis Fitzinger, E. dissimilis. We have sequenced a specimen of E. dissimilis from the type locality and our result suggests that it is part of the Indian radiation of Eutropis and not related to African Trachylepis Fitzinger or Southeast Asian Dasia Gray as previously suggested. Furthermore, we report that the sequence of E. dissimilis used in an earlier study of the once cosmopolitan genus `Mabuya' may have been erroneously identified and appears to be a sequence of E. novemcarinata. We also demonstrate that the evolution of a clear lower eyelid, which was considered a synapomorphy for the sister genus Trachylepis, has arisen multiple times in Eutropis.

Attenuating microwave radiation by absorption through controlled nanoparticle localization in PC/PVDF blends

Nanoscale ordering in a polymer blend structure is indispensable to obtain materials with tailored properties. It was established here that controlling the arrangement of nanoparticles, with different characteristics, in co-continuous PC/PVDF (polycarbonate/poly(vinylidene fluoride)) blends can result in outstanding microwave absorption (ca. 90%). An excellent reflection loss (RL) of ca. -71 dB was obtained for a model blend structure wherein the conducting (multiwall carbon nanotubes, MWNTs) and the magnetic inclusions (Fe3O4) are localized in PVDF and the dielectric inclusion (barium titanate, BT) is in PC. The MWNTs were modified using polyaniline, which facilitates better charge transport in the blends. Furthermore, by introducing surface active groups on BT nanoparticles and changing the macroscopic processing conditions, the localization of BT nanoparticles can be tailored, otherwise BT nanoparticles would localize in the preferred phase (PVDF). In this study, we have shown that by ordered arrangement of nanoparticles, the incoming EM radiation can be attenuated. For instance, when PANI-MWNTs were localized in PVDF, the shielding was mainly through reflection. Now by localizing the conducting inclusion and the magnetic lossy materials in PVDF and the dielectric materials in PC, an outstanding shielding effectiveness of ca. -37 dB was achieved where shielding was mainly through absorption (ca. 90%). Thus, this study clearly demonstrates that lightweight microwave absorbers can be designed using polymer blends as a tool.

Structural evolution and second harmonic properties of lithium niobate-tantalate nanocrystals embedded in a borate glass

Nano-crystals of LiNbxTa1 (-) O-x(3) were evolved by subjecting melt-quenched 1.5Li(2)O-2B(2)O(3)-xNb(2)O(5)-(1 - x)Ta2O5 glasses (where x = 0, 0.25, 0.5, 0.75 and 1.00) to a controlled 3-h isothermal heat treatment between 530 and 560 degrees C. Detailed X-ray diffraction and Raman spectral studies confirmed the formation of nano-crystalline LiNbxTa1 (-) O-x(3) along with a minor phase of ferroelectric and non-linear optic Li2B4O7. The sizes of the nanocrystals evolved in the glass were in the range of 19-37 nm for x = 0-0.75 and 23-45 nm for x = 1.00. Electron microscopic studies confirmed a transformation of the morphology of the nano-crystallites from dendritic star-shaped spherulites for x = 0 to rod-shaped structures for x = 1.00 brought about by a coalescence of crystallites. Broad Maker-fringe patterns (recorded at 532 nm) were obtained by subjecting the heat-treated glass plates to 1064 nm fundamental radiation. However, an effective second order non-linear optic coefficient, d(eff), of 0.45 pm/V, which is nearly 1.2 times the d(36) of KDP single crystal, was obtained for a 560 degrees C/3 h heat-treated glass of the representative composition x = 0.50 comprising 37 nm sized crystallites. (C) 2015 Elsevier B.V. All rights reserved.

Structural evolution and second harmonic properties of lithium niobate-tantalate nanocrystals embedded in a borate glass

Nano-crystals of LiNbxTa1 (-) O-x(3) were evolved by subjecting melt-quenched 1.5Li(2)O-2B(2)O(3)-xNb(2)O(5)-(1 - x)Ta2O5 glasses (where x = 0, 0.25, 0.5, 0.75 and 1.00) to a controlled 3-h isothermal heat treatment between 530 and 560 degrees C. Detailed X-ray diffraction and Raman spectral studies confirmed the formation of nano-crystalline LiNbxTa1 (-) O-x(3) along with a minor phase of ferroelectric and non-linear optic Li2B4O7. The sizes of the nanocrystals evolved in the glass were in the range of 19-37 nm for x = 0-0.75 and 23-45 nm for x = 1.00. Electron microscopic studies confirmed a transformation of the morphology of the nano-crystallites from dendritic star-shaped spherulites for x = 0 to rod-shaped structures for x = 1.00 brought about by a coalescence of crystallites. Broad Maker-fringe patterns (recorded at 532 nm) were obtained by subjecting the heat-treated glass plates to 1064 nm fundamental radiation. However, an effective second order non-linear optic coefficient, d(eff), of 0.45 pm/V, which is nearly 1.2 times the d(36) of KDP single crystal, was obtained for a 560 degrees C/3 h heat-treated glass of the representative composition x = 0.50 comprising 37 nm sized crystallites. (C) 2015 Elsevier B.V. All rights reserved.

Thermo-optic Degradation of Single-Modedness in Active LMA fibers and Simple Compensation Mechanisms

We demonstrate significant thermo-optic degradation of single-modedness in active large mode area fibers due to heat generation in the fiber. We propose and demonstrate through simulations, simple compensation mechanisms using custom length dependent fiber coiling.

Sound radiation from a perforated panel set in a baffle with a different perforation ratio

A finite flexible perforated panel set in a differently perforated rigid baffle is considered. The radiation efficiency from such a panel is derived using a 2-D wavenumber domain formulation. This generalization is later used to represent a more practical case of a perforated panel fixed in an unperforated baffle. The perforations are in the form of an array of uniformly distributed circular holes. A complex impedance model for the holes available in the literature is used. An averaged fluid particle velocity is derived using the continuity equation and the surface pressure is derived using an appropriate momentum equation. The discontinuity in the perforate impedance (due to different hole dimensions or perforation ratio) at the panel-baffle interface is carefully taken into account. It is found that there exists a `coupling' of different wavenumbers of the spatially mean fluid particle velocity field. The change in the resonance frequencies and the modeshapes of the panel due to the perforations is taken into account using the Receptance method. Analytical expressions for the radiated power and radiation efficiency are derived in an integral form and numerical results are presented. Several comparisons are made to understand the radiation efficiency curves. Since both the resistive and reactive components of the hole impedance are taken into account, the model is directly applicable to micro-perforated panels also. (C) 2016 Elsevier Ltd. All rights reserved.

Effect of ambient pressure and radiation reabsorption of atmosphere on the flame spreading over thermally thin combustibles in microgravity

For the flame spread over thermally thin combustibles in an atmosphere, if the atmosphere cannot emit and absorb the thermal radiation (e.g. for atmosphere Of O-2-N-2), the conductive heat transfer from the flame to the fuel surface dominates the flame spread at lower ambient atmosphere. As the ambient pressure increases, the flame spread rate increases, and the radiant heat transfer from the flame to the fuel surface gradually becomes the dominant driving force for the flame spread. In contrast, if the atmosphere is able to emit and absorb the thermal radiation (e.g. for atmosphere Of O-2-CO2), at lower pressure, the heat transfer from flame to the fuel surface is enhanced by the radiation reabsorption of the atmosphere at the leading edge of the flame, and both conduction and thermal radiation play important roles in the mechanism of flame spread. With the increase in ambient pressure, the oxygen diffuses more quickly from ambient atmosphere into the flame, the chemical reaction in the flame is enhanced, and the flame spread rate increases. When the ambient pressure is greater than a critical value, the thermal radiation from the flame to the solid surface is hampered by the radiation reabsorption of ambient atmosphere with the further increase in ambient pressure. As a result, with the increase in ambient pressure, the flame spread rate decreases and the heat conduction gradually dominates the flame spread over the fuel surface.

High speed liquid crystal over silicon display based on the flexoelectro-optic effect.

One of the key technologies to evolve in the displays market in recent years is liquid crystal over silicon (LCOS) microdisplays. Traditional LCOS devices and applications such as rear projection televisions, have been based on intensity modulation electro-optical effects, however, recent developments have shown that multi-level phase modulation from these devices is extremely sought after for applications such as holographic projectors, optical correlators and adaptive optics. Here, we propose alternative device geometry based on the flexoelectric-optic effect in a chiral nematic liquid crystal. This device is capable of delivering a multilevel phase shift at response times less than 100 microsec which has been verified by phase shift interferometry using an LCOS test device. The flexoelectric on silicon device, due to its remarkable characteristics, enables the next generation of holographic devices to be realized.