Interconnected Pt-Nanodendrite/DNA/Reduced-Graphene-Oxide Hybrid Showing Remarkable Oxygen Reduction Activity and Stability

Tiwari, Jitendra N.,Kemp, Kingsley Christian,Nath, Krishna,Tiwari, Rajanish N.,Nam, Hong-Gil,Kim, Kwang S. American Chemical Society 2013 ACS NANO Vol.7 No.10

<P>Controlling the morphology and size of platinum nanodendrites (PtDs) is a key factor in improving their catalytic activity and stability. Here, we report the synthesis of PtDs on genomic-double-stranded-DNA/reduced-graphene-oxide (gdsDNA/rGO) by the NaBH<SUB>4</SUB> reduction of H<SUB>2</SUB>PtCl<SUB>6</SUB> in the presence of plant gdsDNA. Compared to industrially adopted catalysts (<I>i.e.</I>, state-of-the-art Pt/C catalyst, Pt/rGO, Pt<SUB>3</SUB>Co, <I>etc.</I>), the as-synthesized PtDs/gdsDNA/rGO hybrid displays very high oxygen reduction reaction (ORR) catalytic activities (much higher than the 2015 U.S. Department of Energy (DOE) target values), which are the rate-determining steps in electrochemical energy devices, in terms of onset-potential, half-wave potential, specific-activity, mass-activity, stability, and durability. Moreover, the hybrid exhibits a highly stable mass activity for the ORR over a wide pH range of 1–13. These exceptional properties would make the hybrid applicable in next-generation electrochemical energy devices.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2013/ancac3.2013.7.issue-10/nn4038404/production/images/medium/nn-2013-038404_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn4038404'>ACS Electronic Supporting Info</A></P>

Titanium Dioxide Nanomaterials and its Derivatives in the Remediation of Water: Past, Present and Future

Tiwari, Alka,Shukla, Alok,Tiwari, Diwakar,Choi, Suk Soon,Shin, Hyun-Gon,Lee, Seung-Mok The Korean Society of Industrial and Engineering C 2019 공업화학 Vol.30 No.3

The aim of this review article is to summarize the role of titanium oxide ($TiO_2$) nanomaterials in the remediation of the aquatic environment contaminated with various emerging pollutants. The advanced oxidation process led by the semiconductor $TiO_2$ is an impetus in the remediation technology. Therefore, a vast number of literature works are available in this area. Further, the role of modified $TiO_2$ or thin film materials were discussed in the review. Also, the Localized Surface Plasmon Resonance (LSPR) effect of using noble metaldoped $TiO_2$ played an interesting role in the remediation process.

Titanium Dioxide Nanomaterials and its Derivatives in the Remediation of Water: Past, Present and Future

( Alka Tiwari ),( Alok Shukla ),( Diwakar Tiwari ),( Suk Soon Choi ),( Hyun-gon Shin ),( Seung-mok Lee ) 한국공업화학회 2019 공업화학 Vol.30 No.3

The aim of this review article is to summarize the role of titanium oxide (TiO₂) nanomaterials in the remediation of the aquatic environment contaminated with various emerging pollutants. The advanced oxidation process led by the semiconductor TiO₂ is an impetus in the remediation technology. Therefore, a vast number of literature works are available in this area. Further, the role of modified TiO₂ or thin film materials were discussed in the review. Also, the Localized Surface Plasmon Resonance (LSPR) effect of using noble metaldoped TiO₂ played an interesting role in the remediation process.

Au-nanoparticle/nanopillars TiO2 meso-porous thin films in the degradation of tetracycline using UV-A light

Alka Tiwari,Alok Shukla,Lalliansanga,Diwakar Tiwari,이승목 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.69 No.-

Novel meso-porous nanoparticles Au/TiO2 thin films were obtained by template synthesis using polyethylene glycol as filler medium. The materials were characterized by advanced analytical methods. The photocatalysts were employed for the photocatalytic degradation of tetracycline from aqueous solutions using UV-A light (λmax 330 nm). Various physico-chemical parametric studies enabled to deduce the mechanism of degradation. A significant percentage of tetracycline was mineralized by the treatment. The stability of thin film was evidenced with the repeated use of thin film. The degradation of tetracycline was proceeded predominantly by the OH radicals generated at the valance and conduction band of semiconductor.

Engineering a novel bilayer membrane for bone defects regeneration

Tiwari, A.P.,Joshi, M.K.,Maharjan, B.,Ko, S.W.,Kim, J.I.,Park, C.H.,Kim, C.S. North-Holland 2016 Materials letters Vol.180 No.-

We report the fabrication of a novel bilayer scaffold as a barrier membrane via modified-solvent casting and evaporation technique for the regeneration of bone defects. The blended solution of polycaprolactone (PCL) and calcium carbonate (CaCO<SUB>3</SUB>) was treated with hydrochloric acid (HCL), which resulted in the in situ formation of carbon dioxide (CO<SUB>2</SUB>) and water. This led to the phase separation between the PCL and calcium-based compounds and subsequently to the formation of a bilayer membrane. Surface morphology, surface wettability, and energy-dispersive X-ray spectroscopy (EDX) analysis confirmed the formation of a bilayered construct with a PCL-rich thin layer on the upper surface and a calcium-rich porous layer on the lower surface. From the FE-SEM images, the PC30 membrane showed a smooth upper layer with pores less than 10@?m diameter, whereas the lower layer contained many interconnected larger pores up to 1000@?m diameter in addition to the visibly identified macrovoids. The cell adhesion assay showed that both surfaces of the membrane responded well to the cells. In addition, the upper surface prevented the down-growth of the fibroblasts. The initial results suggest a new strategy for the fabrication of the bilayer membrane for regenerative medicine.

Engineered Carbon-Nanomaterial-Based Electrochemical Sensors for Biomolecules

Tiwari, Jitendra N.,Vij, Varun,Kemp, K. Christian,Kim, Kwang S. American Chemical Society 2016 ACS NANO Vol.10 No.1

<P>The study of electrochemical behavior of bioactive molecules has become one of the most rapidly developing scientific fields. Biotechnology and biomedical engineering fields have a vested interest in constructing more precise and accurate voltammetric/amperometric biosensors. One rapidly growing area of biosensor design involves incorporation of carbon-based nanomaterials in working electrodes, such as one-dimensional carbon nanotubes, two-dimensional graphene, and graphene oxide. In this review article, we give a brief overview describing the voltammetric techniques and how these techniques are applied in biosensing, as well as the details surrounding important biosensing concepts of sensitivity and limits of detection. Building on these important concepts, we show how the sensitivity and limit of detection can be tuned by including carbon-based nanomaterials in the fabrication of biosensors. The sensing of biomolecules including glucose, dopamine, proteins, enzymes, uric acid, DNA, RNA, and 11202 traditionally employs enzymes in detection; however, these enzymes denature easily, and as such, enzymeless methods are highly desired. Here we draw an important distinction between enzymeless and enzyme-containing carbon-nanomaterial-based biosensors. The review ends with an outlook of future concepts that can be employed in biosensor fabrication, as well as limitations of already proposed materials and how such sensing can be enhanced. As such, this review can act as a roadmap to guide researchers toward concepts that can be employed in the design of next generation biosensors, while also highlighting the current advancements in the field.</P>

Modulation of Inula racemosa Hook Extract on Cardioprotection by Ischemic Preconditioning in Hyperlipidaemic Rats

Tiwari Arun Kumar,Gupta Pushpraj S,Prasad Mahesh,Malairajan Paraman 대한약침학회 2022 Journal of pharmacopuncture Vol.25 No.4

Objectives: Hyperlipidemia (HL) is a major cause of ischemic heart diseases. The size-limiting effect of ischemic preconditioning (IPC), a cardioprotective phenomenon, is reduced in HL, possibly because of the opening of the mitochondrial permeability transition pore (MPTP). The objective of this study is to see what effect pretreatment with Inula racemosa Hook root extract (IrA) had on IPC-mediated cardioprotection on HL Wistar rat hearts. An isolated rat heart was mounted on the Langendorff heart array, and then ischemia reperfusion (I/R) and IPC cycles were performed. Atractyloside (Atr) is an MPTP opener. Methods: The animals were divided into ten groups, each consisting of six rats (n = 6), to investigate the modulation of I. racemosa Hook extract on cardioprotection by IPC in HL hearts: Sham control, I/R Control, IPC control, I/R + HL, I/R + IrA + HL, IPC + HL, IPC + NS + HL, IPC + IrA+ HL, IPC + Atr + oxidative stress, mitochondrial function, integrity, and hemodynamic parameters are evaluated for each group. Results: The present experimental data show that pretreatment with IrA reduced the LDH, CK-MB, size of myocardial infarction, content of cardiac collagen, and ventricular fibrillation in all groups of HL rat hearts. This pretreatment also reduced the oxidative stress and mitochondrial dysfunction. Inhibition of MPTP opening by Atr diminished the effect of IrA on IPC-mediated cardioprotection in HL rats. Conclusion: The study findings indicate that pretreatment with IrA e restores IPC-mediated cardioprotection in HL rats by inhibiting the MPTP opening.

Synthesis of sulfur-co-polymer/porous long carbon nanotubes composite cathode by chemical and physical binding for high performance lithium-sulfur batteries

Tiwari, Vimal K.,Song, Hyeonjun,Oh, Yeonjae,Jeong, Youngjin Elsevier 2020 ENERGY Vol.195 No.-

<P><B>Abstract</B></P> <P>The composite cathode of sulfur-rich polymer and long cylindrical porous multiwalled carbon nanotubes (LCNT) is reported for high performance lithium-sulfur (Li–S) batteries through combining both chemical and physical binding strategies of sulfur, respectively. This technique efficiently exploits the synergistic effect of ability of stabilizing the polymeric sulfur. The role of uniform distribution of highly conductive LCNT network is optimized as a cathode host material by solution route. Annealed sulfur-co-polymer (S-co-poly) composites are homogeneously well attached via physisorption with LCNT submicron channel. The composite shows a high discharge capacity of 1040 mAh g<SUP>−1</SUP> in the 1st cycle of galvanostatic charge-discharge at 0.5C. Whereas, the cell maintains a reversible capacity of 610 mAh g<SUP>−1</SUP> after 200 cycles, showing good capacity rate. Therefore, solvent assisted both synthesis and further proper mixing enables high active material utilization whereas porous submicron channel of CNT network, which provides conducting pathway, adsorbs sulfur copolymer homogeneously for better electrochemical performance.</P> <P><B>Highlights</B></P> <P> <UL> <LI> S-co-poly-LCNT composite cathode was fabricated by inverse vulcanization through solution route. </LI> <LI> High discharge capacity and stable cyclability were achieved by combining chemical and physical binding strategies. </LI> <LI> S-co-poly-LCNT composite is a promising cathode material for high performance Li–S battery. </LI> </UL> </P>

Bifunctional Oxygen Electrocatalysis through Chemical Bonding of Transition Metal Chalcogenides on Conductive Carbons

Tiwari, Anand P.,Kim, Doyoung,Kim, Yongshin,Lee, Hyoyoung Wiley (John WileySons) 2017 Advanced energy materials Vol.7 No.14

<P>Improving the electrochemical performance of both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) has been of great interest in emerging renewable energy technologies. This study reports an advanced bifunctional hybrid electrocatalyst for both ORR and OER, which is composed of tungsten disulphide (WS2) and carbon nanotube (CNT) connected via tungsten carbide (WC) bonding. WS2 sheets on the surface of CNTs provide catalytic active sites for electrocatalytic activity while the CNTs act as conduction channels and provide a large surface area. Moreover, the newly formed WC crystalline structure provides an easy path for electron transfer by spin coupling and helps to solve stability issues to enable excellent electrocatalytic activity. In addition, it is found that four to five layers of WS2 sheets on the surface of CNTs produce excellent catalytic activity toward both ORR and OER, which is comparable to noble metals (Pt, RuO2, etc.). These findings show the many advantages enabled by designing highly active, durable, and cost-effective ORR and OER electrocatalysts.</P>

Prediction of a research vessel manoeuvring using numerical PMM and free running tests

Tiwari, Kunal,Hariharan, K.,Rameesha, T.V.,Krishnankutty, P. Techno-Press 2020 Ocean systems engineering Vol.10 No.3

International Maritime Organisation (IMO) regulations insist on reduced emission of CO₂, noxious and other environmentally dangerous gases from ship, which are usually let out while burning fossil fuel for running its propulsive machinery. Contrallability of ship during sailing has a direct implication on its course keeping and changing ability, and tries to have an optimised routing. Bad coursekeeping ability of a ship may lead to frequent use of rudder and resulting changes in the ship's drift angle. Consequently, it increases vessels resistance and also may lead to longer path for its journey due to zigzag movements. These adverse effects on the ship journey obviously lead to the increase in fuel consumption and higher emission. Hence, IMO has made it mandatory to evaluate the manoeuvring qualities of a ship at the designed stage itself. In this paper a numerical horizontal planar motion mechanism is simulated in CFD environment and from the force history, the hydrodynamic derivatives appearing in the manoeuvring equation of motion of a ship are estimated. These derivatives along with propeller thrust and rudder effects are used to simulate different standard manoeuvres of the vessel and check its parameters against the IMO requirements. The present study also simulates these manoeuvres by using numerical free running model for the same ship. The results obtained from both these studies are presented and discussed here.