On the improvement of detection characteristics of trans-stilbene crystals by improving crystal perfection

Organic molecular scintillating crystals are noted for their good timing and particle discrimination process. Trans-stilbene is one such candidate noted for its good particle detection characteristics for the past five decades. Progressive strengthening of detection characteristics of trans-stilbene has been attempted by improving crystal perfection. A series of timing resolution studies have been carried out for the Bridgman grown trans-stilbene crystals under different experimental conditions. The results were compared with the previously reported values. Pulse shape discrimination process has been carried out for ²⁴¹Am and ²⁵²Cf sources and good discrimination has been obtained for gamma-alpha and gamma-neutron sources from the grown organic phosphor crystal. Electronic Publication     

A study on dynamic friction of different spun yarns

This article presents the results from a study of yarn-to-yarn (YY) and yarn-to-metal (YM) frictions conducted on ring, rotor, air-jet, and open-end friction (OE friction) spun yarns at different relative speeds and input tensions. The results indicate that the behavior of frictions for YY is different than that of YM. In case of YY friction, OE friction yarn shows maximum friction followed by rotor, air-jet, and ring spun yarns; however, a reverse order is noticed for YM friction. The relative speed and input tension have significant influence on the frictional behavior of spun yarns. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Phase immiscibility induced enhanced fluorescence in spin-coated PVP/PPO polyblends

We report on the effect of phase immiscibility on the structure and optical properties of spin-coated polyvinylpyrrolidone (PVP) and polyphenylene oxide (PPO) polyblends using X-ray diffraction, IR absorption, optical absorption and florescence spectroscopic techniques. The broad diffraction halos in the X-ray diffraction patterns reveal the semi-crystalline nature for the synthesized polyblends. The change in q value for both the deconvoluted halos confirms the variation in the molecular interactions while the decrease in their fwhm values signify the enhancement in crystalline nature with the blending. The infrared absorption studies were used to elucidate the interaction of functional groups in the spin-coated polyblends. The position of three excitonic bands and the red shift in the optical absorption edge with the increase in the PPO content has been observed for these polyblends. The six time enhancement in fluorescence peak intensity in visible region (~500 nm) for immiscible blend (50/50) composition has been of importance for the design of low cost luminescent and photovoltaic devices.     

Uniplanar ACS fed multiband high‐gain antenna with extended rectangular strips for portable system applications

In this article, a compact uniplanar asymmetric coplanar strip (ACS)‐fed multiband antenna with extended rectangular strips is proposed for portable system applications. It is composed of a modified mouse and rectangular‐shaped radiating strip for generating three resonance frequency bands simultaneously. The proposed antenna has a compact size of 16 × 26 × 1.6 mm³. Antenna has |S₁₁| ≤ ?10 dB at three independent controlled bandwidths from 2.2 to 2.4 GHz, 3.5 to 3.7 GHz, and 4.85 to 6.85 GHz. The proposed ACS‐fed antenna is suitable for LTE 2300, WiBro 2300 GHz, 5.2/5.8‐GHz WLAN, 3.5/5.5‐GHz WiMAX, 4.9‐GHz US public safety band, and 5.9‐GHz WAVE applications. The antenna has omnidirectional radiation characteristics in the desired frequency bands in both E‐plane and H‐plane. It has better gain value performance compared with other antenna designs discussed in the literature.     

Perovskite solar cells: recent progress and strategies developed for minimizing interfacial recombination

Organometallic perovskite is a new generation photovoltaic material with exemplary properties such as high absorption co-efficient, optimal bandgap, high defect tolerance factor and long carrier diffusion length. However, suitable electrodes and charge transport materials are required to fulfill photovoltaic processes where interfaces between hole transport material/perovskite and perovskite/electron transport material are affected by phenomena of charge carrier separation, transportation, collection by the interfaces and band alignment. Based on recent available literature and several strategies for minimizing the recombination of charge carriers at the interfaces, this review addresses the properties of hole transport materials, relevant working mechanisms, and the interface engineering of perovskite solar cell (PSC) device architecture, which also provides significant insights to design and development of PSC devices with high efficiency.     

In-situ synthesis of silica aerogel in polyethylene terephthalate fibre nonwovens and their composite properties on acoustical absorption behavior

In this research work we focus on engineering the silica aerogel/polyethylene terephthalate (PET) fibre nonwoven fabric composites with various silica content during in-situ synthesis of silica aerogels in the nonwovens and their composite properties on sound absorption. The silica content was varied by varying the molar ratio of methanol (MeOH)/tetraethyl orthosilicate (TEOS) from 110 to 28. The gelation of silica alcogel took place inside the fabric followed by silylation and atmospheric pressure drying. The aerogel/PET nonwoven composites were characterized by FTIR, TGA and contact angle to explain the aerogel content and its behavior. Moreover, the physical properties such as thickness, bulk density, specific airflow resistance, and mean flow pore size have been investigated. The two microphone transfer function method was used to test the sound absorption coefficient (SAC) of aerogel composites at 1/3rd octave frequencies of 50–6300 Hz. The aerogel/PET nonwoven composites have exhibited higher SAC than the untreated or control PET nonwoven for the entire frequency range. The suitable solvent molar ratio of 55 has been recommended for synthesis of silica aerogels by considering not only the silica content to have high sound absorption but also based on hydrophobic characteristics of aerogel/PET nonwoven composites.     

Phytosynthesized iron oxide nanoparticles and ferrous iron on fermentative hydrogen production using Enterobacter cloacae: Evaluation and comparison of the effects

The effects of FeSO₄ and synthesized iron oxide nanoparticles (0–250 mg/L) on fermentative hydrogen production from glucose and sucrose, using Enterobacter cloacae were investigated, to find out the enhancement of efficiency. The maximum hydrogen yields of 1.7 ± 0.017 mol H₂/mol glucose and 5.19 ± 0.12 mol H₂/mol sucrose were obtained with 25 mg/L of ferrous iron supplementation. In comparison, the maximum hydrogen yields of 2.07 ± 0.07 mol H₂/mol glucose and 5.44 ± 0.27 mol H₂/mol sucrose were achieved with 125 mg/L and 200 mg/L of iron oxide nanoparticles, respectively. These results indicate that the enhancement of hydrogen production on the supplementation of iron oxide nanoparticles was found to be considerably higher than that of ferrous iron supplementation. The activity of E. cloacae in a glucose and sucrose fed systems was increased by the addition of iron oxide nanoparticles, but the metabolic pathway was not changed. The results revealed that the glucose and sucrose fed systems conformed to the acetate/butyrate fermentation type.     

Dynamic failure behaviour of blended spun yarns during winding

In the present work, the initiative is being taken to study the spun yarn failure behaviour under real dynamic conditions i.e. winding. An attempt is made to study the dynamic failure behaviour of blended ring yarn in relation to yarn structure. Multi-coloured tracer fibre technique is employed to study the broken ends of yarn during the winding process in terms of proportion of fibre break/slip, configuration of yarn broken end and yarn failure length. The ring spun yarn failure during winding is basically dominated by fibre breakage. The length of broken and slipped fibres is found to be different in trailing and leading portion of the broken ends and also depends on viscose content in the blends. The failure zone length and sum of percentage of tapered and slipped broken ends are found to follow the exactly similar trend with fibre failure coefficient with the change in blend ratio. The mathematical model established to explain the spun yarn failure during winding process displays lower error%.     

Development of soy-based UV-curable acrylate oligomers and study of their film properties

Bio-based coating materials have emerged as an environmentally friendly alternative to petrochemical based ones due to their sustainability, lower carbon footprint and often lower cost. Acrylated vegetable oils and their derivatives are increasingly preferred for advanced photo-curable “green” coatings due to a number of technical and commercial benefits. We report a novel family of acrylate-functional monomers/oligomers derived from epoxidized soybean oil (ESO) and epoxidized soy-methyl ester (EME), using 2-hydroxyethyl acrylate (HEA) as an acrylating agent. Using super-acid catalyzed etherification, acrylated soy-monomers and oligomers with lower viscosity and high acrylate content have been synthesized. Soy-acrylate products are characterized for their chemical structures and functionality using chemical, physical and spectroscopic methods.