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Bhattacharya, Pallab,Lee, Joong Hee,Kar, Kamal K.,Park, Ho Seok Elsevier 2019 CHEMICAL ENGINEERING JOURNAL -LAUSANNE- Vol.369 No.-
<P><B>Abstract</B></P> <P>Constructing nanostructures of high capacity materials and hybridizing the same with conductive carbon networks are important for high performing lithium ion batteries. Here, we demonstrate new carambola-shaped crystalline SnO<SUB>2</SUB> (c-SnO<SUB>2</SUB>), which is wrapped in a three-dimensional multiwalled carbon nanotube network (c-SnO<SUB>2</SUB>@3D-CNT). The carambola structure of c-SnO<SUB>2</SUB> is constructed by changing the surface energy of a specific crystalline plane using a potassium fluoride capping agent. The as-designed c-SnO<SUB>2</SUB>@3D-CNT achieves a high capacity of 1140.2 mA·h·g<SUP>−1</SUP> at 50 mA·g<SUP>−1</SUP>, a capacity retention of 50.7% retained at 1000 mA·g<SUP>−1</SUP> relative to 50 mA·g<SUP>−1</SUP>, and a cycling stability of 72.0% over 500 cycles at a high rate of 1000 mA·g<SUP>−1</SUP>. In particular, the c-SnO<SUB>2</SUB>@3D-CNT shows a high volumetric capacity of 1674.8 mA·h·cm<SUP>−3</SUP> at 50 mA·g<SUP>−1</SUP> and 849.2 mA·h·cm<SUP>−3</SUP> at 1000 mA·g<SUP>−1</SUP>, which is greater than those of previous SnO<SUB>2</SUB>-based materials. This finding is associated with the compact packing of hierarchical carambola structure having multiple concave surfaces into dense and porous electrode. Therefore, the hierarchical carambola structure and 3D hybrid architecture provide a buffer space for volume expansion and fast ion/electronic conducting pathways, which impart a high volumetric capacity, improved cyclic and rate performances, and higher reversibility than other SnO<SUB>2</SUB> materials.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Hierarchically carambola morphology of SnO<SUB>2</SUB> is constructed. </LI> <LI> SnO<SUB>2</SUB> electrode achieves high tap density and porous structure. </LI> <LI> Wrapping by 3D MWCNT network extends the cycle life. </LI> <LI> 3D conductive path boosts the rate capability. </LI> <LI> Carambola shaped SnO<SUB>2</SUB> show high volumetric capacity. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Bhattacharya, Pallab,Kota, Manikantan,Suh, Dong Hoon,Roh, Kwang Chul,Park, Ho Seok Wiley Blackwell (John Wiley Sons) 2017 ADVANCED ENERGY MATERIALS Vol.7 No.17
<P>It is crucial to control the structure and composition of composite anode materials to enhance the cell performance of such anode materials for lithium ion batteries. Herein, a biomimetic strategy is demonstrated for the design of high performance anode materials, inspired by the structural characteristics and working principles of sticky spider-webs. Hierarchically porous, sticky, spider-web-like multiwall carbon nanotube (MWCNT) networks are prepared through a process involving ozonation, ice-templating assembly, and thermal treatment, thereby integrating the networks with gamma-Fe2O3 particles. The spider-web-like MWCNT/gamma-Fe2O3 composite network not only traps the active gamma-Fe2O3 materials tightly but also provides fast charge transport through the 3D internetworked pathways and the mechanical integrity. Consequently, the composite web shows a high capacity of similar to 822 mA h g(-1) at 0.05 A g(-1), fast rate capability with similar to 72.3% retention at rates from 0.05 to 1 A g(-1), and excellent cycling stability of > 88% capacity retention after 310 cycles with a Coulombic efficiency > 99%. These remarkable electrochemical performances are attributed to the complementarity of the 3D spider-web-like structure with the strong attachment of gamma-Fe2O3 particles on the sticky surface. This synthetic strategy offers an environmentally safe, simple, and cost-effective avenue for the biomimetic design of high performance energy storage materials.</P>
OPTOELECTRONIC INTEGRATED CIRCUITS FOR PHOTORECEIVERS AND COMMUNICATION SYSTEMS
Bhattacharya, Pallab 대한전자공학회 1989 ICVC : International Conference on VLSI and CAD Vol.1 No.1
Optoelectronic Integrated Circuits (OEICs), circuits that monolithically integrate lasers or photodetectors with electron components on a single semiconductor chip, are a device technology with the potential to meet a broad range of future telecommunications and computer system needs. As for the case of integrated electronics, monolithic integration of optical and electrical devices offers significant advantages over hybrid circuits in compactness and reliability, as well as for potential reduction in cost and for possible performance improvements resulting from reduced parasitics. In this paper I describe our work on monolithically integrated photoreceivers which use HEMTs, SISFETs, APDs and Camel diodes as components. I will also describe a monolithically integrated MQW bipolar optoelectronic switch and integration on optical fiber surfaces made by MBE and ex-situ processing.
Bhattacharya, Pallab,Joo, Taigyu,Kota, Manikantan,Park, Ho Seok Elsevier 2018 Ceramics international Vol.44 No.1
<P><B>Abstract</B></P> <P>The integration of pseudocapacitive metal oxides with reduced graphene oxide (RGO) is considered an innovative chemical strategy to resolve both bottlenecks of pseudocapacitor and electrical double-layer capacitor for high performance supercapacitors. Herein, we report a facile synthesis method of highly porous three-dimensional (3D) CoO/RGO nanocomposite via ozone treatment, ice templating, and thermal annealing. The ozonized RGO surface provides a favorable interaction with cobalt precursor for a stable and uniform deposition of well-defined CoO nanoparticles. The morphology, structure, and chemistry of the resulting CoO/RGO nanocomposites are comprehensively characterized by spectroscopic methods. The CoO/RGO nanocomposites show fast and reversible pseudocapacitance due to a large accessible area, rapid ion transport, and low charge transfer resistance arising from 3D internetworked macroporosity. Thus, the nanocomposites achieve high specific capacitance up to 239.4Fg<SUP>-1</SUP> (volumetric capacitance = 12.04Fcm<SUP>-3</SUP>), excellent rate capability of 79.1%, and ultralong cyclic stabilities (of 93.2% at 10Ag<SUP>-1</SUP> even up to 10,000 cycles) in 6M KOH electrolyte. This simple synthesis method offers a promising solution for the design of high performance hybrid energy storage materials consisting of high capacity metal oxides and conductive graphene networks.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Nonlinear viscoelastic behavior of aqueous foam under large amplitude oscillatory shear flow
Badri Vishal,Pallab Ghosh 한국유변학회 2018 Korea-Australia rheology journal Vol.30 No.3
Aqueous foams are dispersions of gas bubbles in water, stabilized by surfactant, and sometimes particles. This multiphasic composition gives rise to complex rheological behavior under deformation. Understanding this behavior is important in many applications. Foam shows nonlinear rheological behavior at high deformation, which can be investigated by the large amplitude oscillatory shear (LAOS) experiments. In the present work, we have performed a systematic LAOS study of foam stabilized by 0.1 mol m−3 hexadecyltrimethylammonium bromide and 0.5 wt.% silica nanoparticles. The Lissajous-Bowditch curves and stress waveforms were analyzed at various strain amplitudes. These curves were fitted by Fourier transform rheology and Chebyshev polynomials to understand the contribution of the higher harmonic terms in LAOS. The intracycle LAOS behavior was explained based on the sequence of physical processes. The foam exhibited intracycle strain-hardening and shear-thinning at high deformation. Shear-thickening behavior was observed at moderate deformations.
Applications, treatments, and reuse of plastics from electrical and electronic equipment
Chunmiao Jia,Pallab Das,김인섭,윤용진,Chor Yong Tay,Jong-Min Lee 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.110 No.-
Waste of electrical and electronic equipment (WEEE, also known as E-Waste) has emerged as a seriousissue for the whole world along with the evolution of modern industry. WEEE plastic contains heavy metals(arsenic, mercury, chromium, cadmium, lead, etc.) and halogen materials (bromine, chlorine, etc.),which are toxic and harmful to the environment, therefore the recycling of WEEE plastic is necessaryand critical. Not only the various additives in the polymer but also the contaminations from polychlorinatedbiphenyl (PCB), batteries, etc, make the recycling process challenging. In this review, the functionalapplication of plastic in electrical and electronic equipment (EEE) including electrical insulation, heatinsulation, etc, is firstly introduced. The various components and additives of plastic in EEE are provided. Moreover, the state-of-the-art treatment and recycle methods of the WEEE plastic are summarized anddiscussed. This review can provide a comprehensive reference for investigation of plastic in e-waste.
Preclinical evaluation of Kali Haldi (Curcuma caesia): a promising herb to treat type-2 diabetes
Poulami Majumder,Pallab Kanti Haldar,Suchandra Mazumder,Mainak Chakraborty,Srila Ghosh Chowdhury,Samit Karmakar 경희대학교 융합한의과학연구소 2017 Oriental Pharmacy and Experimental Medicine Vol.17 No.2
The methanol extract of Curcuma caesia (MECC) rhizome showed antidiabetic activity by lowering blood glucose in in vivo studies and controlled intestinal absorption of monosaccharides by inhibiting alpha amylase and alpha glucosidase. It also enhanced the glucose uptake in yeast cells, proving proper glucose utilization. The IC50 values of MECC were found to be 442.92 ± 10.05 μg/ml and 95.40 ± 9.74 μg/ml in alpha amylase and alpha glucosidase inhibition respectively. The extract has effective antioxidant activities, by successfully scavenging free radicals like superoxide and hydroxyl ions. The histopathological studies of pancreas showed gradual healing after treatment.