Investigation on the bulk growth of $${\upalpha }$$-$$\hbox {LiIO}_{3}$$LiIO3 single crystals and the influence of pH on its structural,morphological and optical characteristics

\(\upalpha \)-\(\hbox {LiIO}_{3}\) is an excellent optical material exhibiting strong nonlinear optical, piezoelectric and elasto-optic properties. However, its practical applications are limited by the insufficient reproducibility of the mentioned properties caused by the strong influence of the growth conditions, and, in particular, pH of the solution from which \(\upalpha \)-\(\hbox {LiIO}_{3}\) crystal is grown. Herein, we investigate to grow bulk size good quality crystals of \(\upalpha \)-\(\hbox {LiIO}_{3}\) based on the observed problems during its crystallization process. A systematic investigation was carried out to find the effect of pH on solubility, crystal growth, structural, surface and laser damage properties of \(\upalpha \)-\(\hbox {LiIO}_{3}\) single crystals. The structure and phase of \(\hbox {LiIO}_{3}\) were confirmed by powder X-ray diffractometer analysis. The functional groups of the compound were identified using Fourier transform infrared spectroscopy. Surface defects of the grown crystals were studied by etch patterns. The crystal grown at pH 10 showed 10% optical transmission enhancement in comparison to the crystals grown at pH 2. The indirect optical bandgap of the crystal was reinvestigated using ultraviolet–Visible–near-infrared transmittance spectrum. The laser damage threshold studies of the crystals grown at pH 10 reveal the higher optical radiation stability against 532 nm laser. The second-order nonlinear optical behaviour of \(\upalpha \)-\(\hbox {LiIO}_{3}\) crystals grown at different pH conditions have been investigated by using Kurtz and Perry powder technique with Nd:YAG laser pulses at the wavelength of 1064 nm.     

Cut-growth behaviour of EPDM-bromobutyl rubber blends under repeated stressing

Cut-growth behaviour of ethylene-propylene -diene rubber (EPDM), bromobutyl rubber (BIIR) and their blends under dynamic loading has been studied over a range of temperatures. The crack-growth resistance increases with the increase of BIIR content in the gum and filled blends. The 30: 70 EPDM : BIIR blend, however, gives the best fatigue resistance because of morphology and strain energy density factors. Failure surfaces have been examined both by photography and electron microscopic techniques. The crack always propagates from the precut. The rate of crack propagation is faster for EPDM gum samples. The blends show fracture features intermediate between those of fractured BIIR and EPDM rubbers. Straight flow lines, cracks and fatigue striations (10 to 15m distance between two consecutive striations) are observed for gum samples. The flow lines are increased and the cracks are reduced for filled samples. The fractography of the crack front at the precut and that away from it are similar. At a higher temperature (100° C), there is a reduction of fatigue life for the blends and pure rubbers. Many cracks are observed on the fracture surface of gum and filled samples.     

Effect of Intermittent Overload Cycles on Thermomechanical Fatigue Life of NiTi Shape Memory Alloy Wire

Effect of intermittent overload cycles on fatigue behavior of NiTi shape memory alloy wire during thermomechanical cycling (TMC) has been evaluated. Results showed that fatigue life of NiTi is enhanced when the intermittent overload is above certain minimum level. An enhancement in fatigue life by ~50 pct is observed when the overload ratio is 2.0. Accumulation of plastic strain in the material under such TMC condition is found to be relatively high compared to that of TMC with no overload cycles.     

Virtualized controller placement for multi-domain optical transport networks using machine learning

Photonic Network Communications - Optical multi-domain transport networks are often controlled by a hierarchical distributed architecture of controllers. Optimal placement of these controllers is...     

A CAD approach for suppression of power supply noise and performance analysis of some multi-core processors in pre-layout stage

In modern system-on-chip, the number of transistors has grown exponentially. This requires an efficient electrical power distribution network for proper functioning of the chip. Voltages at different nodes with respect to the desired level may vary which correspond to generation of supply noise. This paper deals with the estimation and allocation of decoupling capacitance for reduction of supply noise at the pre-layout level. Usually, decoupling capacitors are placed near the noisy functional modules, which acts as local charge storing devices and effectively reduce the transients. In this work, analysis of various sources of supply noises has been performed. Depending on the amount of supply noise, the decoupling capacitance has been estimated and allocated with minimum increment in power consumption and propagation delay. We have considered 512-points, 1-k point, 2-k point and 4-k point Fast Fourier Transform processors and International Test Conference 1999 (b14 and b17) benchmark circuits as our test circuits. This work reports up to 51.9% reduction of peak supply noise at the cost of 0.48 and 1.44% increase in power consumption and delay respectively. This estimation and subsequent allocation of decoupling capacitances will help for more accurate design and implementation at the layout stage.

     

Effect of Electrode Materials on Different EDM Aspects of Titanium Alloy

Silicon - Electro discharge machining (EDM) is extensively used in modern manufacturing industry because of its advantage over conventional machining method. Titanium alloys are the materials of...     

Solid acid catalyzed synthesis of furans from carbohydrates

The alternative feedstock, biomass (particularly lignocelluloses), having the profuse availability, is promising for the synthesis of several value-added chemicals which are currently obtained from fossil feedstock. In this article, the synthesis of two extremely significant furan chemicals viz. furfural and 5-hydroxymethylfurfural (HMF) are discussed. In the synthesis of furans from biomass, numerous challenges, i.e., use of edible sugars as substrates, selectivity to furans, their isolation in pure form, reuse of catalyst, environmental issues, etc., are perceived and in the recent past researchers tried to resolve those by developing advance methodologies. This article comprehensively summarizes the latest progress made in the above-mentioned areas and also provides commentary on the analyses of results, rationale for observed activity and mechanisms, etc. It also discusses future aspects of this work.     

Selective Zinc(II)‐Ion Fluorescence Sensing by a Functionalized Mesoporous Material Covalently Grafted with a Fluorescent Chromophore and Consequent Biological Applications

A highly ordered 2D‐hexagonal mesoporous silica material is functionalized with 3‐aminopropyltriethoxysilane. This organically modified mesoporous material is grafted with a dialdehyde fluorescent chromophore, 4‐methyl‐2,6‐diformyl phenol. Powder X‐ray diffraction, transmission electron microscopy, N₂ sorption, Fourier transform infrared spectroscopy, and UV‐visible absorption and emission have been employed to characterize the material. This material shows excellent selective Zn²⁺ sensing, which is due to the fluorophore moiety present at its surface. Fluorescence measurements reveal that the emission intensity of the Zn²⁺‐bound mesoporous material increases significantly upon addition of various concentrations of Zn²⁺, while the introduction of other biologically relevant (Ca²⁺, Mg²⁺, Na⁺, and K⁺) and environmentally hazardous transition‐metal ions results in either unchanged or weakened intensity. The enhancement of fluorescence is attributed to the strong covalent binding of Zn²⁺, evident from the large binding constant value (0.87 × 10⁴ M ^?1). Thus, this functionalized mesoporous material grafted with the fluorescent chromophore could monitor or recognize Zn²⁺ from a mixture of ions that contains Zn²⁺ even in trace amounts and can be considered as a selective fluorescent probe. We have examined the application of this mesoporous zinc(II) sensor to cultured living cells (A375 human melanoma and human cervical cancer cell, HeLa) by fluorescence microscopy.     

Sn-ZSM-12, a new,large pore MTW type tin-silicate molecular sieve: synthesis,characterization and catalytic properties in oxidation reactions

A new large pore tin-silicate analogue of zeolite ZSM-12 (MTW topology) with Si/Sn molar ratio >70 has been synthesized hydrothermally using a new template, hexamethylene bis(benzyl dimethyl ammonium hydroxide). This material exhibits an expansion in unit cell volume (XRD), an IR band at 970 cm^–1 and a charge transfer band at 205 nm in the UV-Vis region indicating the presence of Si-O-Sn units with Sn⁴⁺ centers in T_d configuration. Sn-ZSM-12 catalyzes the oxidation of phenol,m-cresol andm-xylene using dilute H₂O₂ as an oxidizing agent.