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     

An Efficient Near Lossless Image Compression Algorithm Using Dissemination of Spatial Correlation for Remote Sensing Color Images

Wireless Personal Communications - Image transmission from space borne equipment is a challenging task owing to its restrictions on bandwidth and memory requirement. Many of the state of art...     

Polysulfobetaine bearing tertiary amide between counterions and its applications

Modified sulfobetaine bearing tertiary amide spacer between the counterions is synthesized and polymerized by reversible addition–fragmentation chain transfer polymerization technique. The tertiary amide spacer influences various characteristics of the zwitterionic polymer. The modified polyzwitterion, PZI, forms coacervates in deionized water. The coacervates are thoroughly characterized by scanning electron microscopy, transmission electron microscopy, and transmittance studies. The ability to form coacervate complexes with functional ingredients has been demonstrated by encapsulating renewable resource actives like ferulic acid. The coacervate complexes have been studied by optical microscopy, transmission electron microscopy, and automated sunscreen sun protection factor analyzer. Synergism is noticed in the coacervate complex. Because of its ability to form self‐coacervates, this novel addition to the zwitterionic family is potentially useful for encapsulating many functional ingredients through coacervate complex formation. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46178.     

3D Printed Cobalt-Chromium-Molybdenum Porous Superalloy with Superior Antiviral Activity

COVID-19 pandemic and associated supply-chain disruptions emphasise the requirement for antimicrobial materials for on-demand manufacturing. Besides aerosol transmission, SARS-CoV-2 is also propagated through contact with virus-contaminated surfaces. As such, the development of effective biofunctional materials that can inactivate SARS-CoV-2 is critical for pandemic preparedness. Such materials will enable the rational development of antiviral devices with prolonged serviceability, reducing the environmental burden of disposable alternatives. This research reveals the novel use of Laser Powder Bed Fusion (LPBF) to 3D print porous Cobalt-Chromium-Molybdenum (Co-Cr-Mo) superalloy with potent antiviral activity (100% viral inactivation in 30 min). The porous material was rationally conceived using a multi-objective surrogate model featuring track thickness (tt) and pore diameter (ϕd) as responses. The regression analysis found the most significant parameters for Co-Cr-Mo track formation to be the interaction effects of scanning rate (Vs) and laser power (Pl) in the order PlVs>Vs>Pl. Contrastively, the pore diameter was found to be primarily driven by the hatch spacing (Sh). The study is the first to demonstrate the superior antiviral properties of 3D printed Co-Cr-Mo superalloy against an enveloped virus used as biosafe viral model of SARS-CoV-2. The material significantly outperforms the viral inactivation time of other broadly used antiviral metals such as copper and silver, as the material’s viral inactivation time was from 5 h to 30 min. As such, the study goes beyond the current state-of-the-art in antiviral alloys to provide extra protection to combat the SARS-CoV-2 viral spread. The evolving nature of the COVID-19 pandemic brings new and unpredictable challenges where on-demand 3D printing of antiviral materials can achieve rapid solutions while reducing the environmental impact of disposable devices.     

Impulsively fractional-order time-delayed gene regulatory networks: Existence and asymptotic stability

This paper presents asymptotic stability criteria for fractional-order gene regulatory networks (FOGRNs) with impulses, time delays, and two numerical cases to illustrate the applicability of the results. The established system's boundedness, existence, and uniqueness are discussed using the Mittag–Leffler function, homeomorphism theory, and Cauchy–Schwartz inequality. The delay-independent asymptotic stability criteria for FOGRNs are derived using algebraic and LMI methods, famous inequality techniques, and Lyapunov stability theory.     

A Scheduling Framework for UWB & Cellular Networks

The max-min fair scheduling problem in wireless ad-hoc networks is a non-convex optimization problem. A general framework is presented for this optimization problem and analyzed to obtain a dual problem, which involves solving a series of optimization sub-problems. In the limit of infinite bandwidth ( ), the scheduling solution reduces to simultaneous transmission (spread spectrum) on all links (Negi and Rajeswaran, INFOCOM '04 (March 2004)). This motivates the analysis of the scheduling problem in the Ultra Wide Band (UWB) regime ( , but finite), a model for certain practical radios. A quadratic (in 1/W) lower bound to the single link capacity function is developed, which simplifies the dual sub-problem to a quadratic optimization (Negi and Rajeswaran, GLOBECOM '04, (Dec. 2004)). The solution to this sub-problem is then obtained under both total power and power spectral density constraints. This solution is utilized to iteratively construct the schedule (sub-band sizes) and power allocation, thus optimally solving the UWB max-min fair scheduling problem, to within any desired precision. Simulations on medium sized networks demonstrate the excellent performance of this scheme. A cellular architecture (not necessarily UWB) may also be considered in this framework. It is proved that Frequency Division Multiple Access is the optimal scheduling for a multi-band cellular architecture. This work was supported in part by the National Science Foundation under Career award 0347455. Arjunan Rajeswaran received his Masters degree in Electrical and Computer Engineering from Carnegie Mellon University in 2003. Since August 2003, he has been pursuing his doctoral research at Carnegie Mellon. His reserach interests lie in the area of wireless networks. His focus is in the application of information and communication theoretic tools towards wireless network design. Several IEEE publications reflect his curent research on Medium Access Control design and performance. Arjunan received the best student paper award at IEEE/ACM Broadnets 2004. Gyouhwan Kim received his B.S. and M.S. degree in Electronic Engineering from Sogang University in Korea, in 1994 and 1996, respectively. Since 1996, he has been working in the CDMA cellular system development team in Samsung Electronics. Currently, he is also working toward the Ph.D degree in the Department of Electrical and Computer Engineering at Carnegie Mellon University. His main research interests are in wireless networks and communication theory. Rohit Negi received the B.Tech. degree in Electrical Engineering from the Indian Institute of Technology, Bombay, India in 1995. He received the M.S. and Ph.D. degrees from Stanford University, CA, USA, in 1996 and 2000 respectively, both in Electrical Engineering. He has received the President of India Gold medal in 1995. Since 2000, he has been with the Electrical and Computer Engineering department at Carnegie Mellon University, Pittsburgh, PA, USA, where he is an Assistant Professor. His research interests include signal processing, coding for communications systems, information theory, networking, cross-layer optimization and sensor networks.     

A new high-performance supercapacitor electrode of strategically integrated cerium vanadium oxide and polypyrrole nanocomposite

Herein we show a construction of high-performance supercapacitor electrode made of cerium vanadate uniformly glazed over polypyrrole (CeVO₄/Ppy) nanostructures by a simple hydrothermal method, which was characterized by various analytical techniques. Electrochemical studies on CeVO₄/Ppy/Ni foam with 1 M KOH show a maximum specific capacitance of 1236 F/g at a current density of 0.75 A/g. These salient features, together with smart interactions between the interconstituents, CeVO₄ and Ppy, lead to high conductivity, specific capacitance, and cycling stability with retention of 92.6% capacitance in 10,000 cycles of GCD curves. Additionally, the asymmetric supercapacitor based on activated carbon (AC), AC//CeVO₄/Ppy device delivers a high specific capacitance of 116 F/g and energy density of 52.2 Wh/Kg at power density of 675.9 W/kg along with high capacity retention of 77.80% after 10,000 cycles. This system could be scaled up to large-scale production of high power devices, which opens up lot of opportunities in modern electronic industrial applications.     

Imidazolium-Based Stabilization of Aqueous Multiwall Carbon Nanotube Dispersions

Imidazolium bromide, an ionic liquid surfactant acrylate, as well as its homopolymer and various copolymers are demonstrated to be superior dispersing aids for preparing aqueous multiwall carbon nanotube (MWCNT) dispersions. We demonstrate apparent complete exfoliation in water with extinction coefficients at 500 nm of about 60 cm² mg⁻¹ of MWCNT dispersed, a new lower bound and the highest reported extinction to date. The efficacy or efficiency of dispersion (activated by ultrasonication) is examined in terms of a quotient of extinction and weight ratio of the active monomer and MWCNT. A rank ordering of the results obtained for seven stabilizers based on the same imidazolium bromide monomer provides insights into roles of π-overlap adsorption onto MWCNT surfaces and how hydrogel properties of some of these polymers provide stability in water at higher concentrations than previously considered feasible for surfactant-stabilized and polymer-stabilized MWCNT dispersions. Simple nanocomposite film formation is demonstrated by casting and thermal diffusivity and electrical conductivity properties are examined.     

Effect of silica fume, metakaolin, and low-calcium fly ash on chemical resistance of concrete

Effects of aggressive chemical environments were evaluated on the mortars prepared with ordinary portland cement (OPC) and silica fume (SF)/metakaolin (MK)/low-calcium fly ash at various replacement levels. The natural adverse chemical environmental conditions were simulated using sulfuric acid, hydrochloric acid, nitric acid, acetic acid, phosphoric acid, and a mixture of sodium and magnesium sulfates. Chemical resistance information was used in conjunction with compressive strength measurements to propose realistic OPC/mineral admixture proportions.