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.

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.

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.

Point-Wise Fusion of Distributed Gaussian Process Experts (FuDGE) Using a Fully Decentralized Robot Team Operating in Communication-Devoid Environment

Tiwari, Kshitij,Jeong, Sungmoon,Chong, Nak Young IEEE 2018 IEEE TRANSACTIONS ON ROBOTICS Vol.34 No.3

<P>In this paper, we focus on large-scale environment monitoring by utilizing a fully decentralized team of mobile robots. The robots utilize the resource constrained-decentralized active sensing scheme to select the most informative (uncertain) locations to observe while conserving allocated resources (battery, travel distance, <I>etc.</I>). We utilize a distributed Gaussian process (GP) framework to split the computational load over our fleet of robots. Since each robot is individually generating a model of the environment, there may be conflicting predictions for test locations. Thus, in this paper, we propose an algorithm for aggregating individual prediction models into a single globally consistent model that can be used to infer the overall spatial dynamics of the environment. To make a prediction at a previously unobserved location, we propose a novel gating network for a mixture-of-experts model wherein the weight of an expert is determined by the responsibility of the expert over the unvisited location. The benefit of posing our problem as a centralized fusion with a distributed GP computation approach is that the robots never communicate with each other, individually optimize their own GP models based on their respective observations, and off-load all their learnt models on the base station only at the end of their respective mission times. We demonstrate the effectiveness of our approach using publicly available datasets.</P>

Activated Sericite: An Efficient and Effective Natural Clay Material for Attenuation of Cesium from Aquatic Environment

TIWARI, D.,LALHMUNSIAMA,,CHOI, S.I.,LEE, S.M. Elsevier 2014 Pedosphere an international journal Vol.24 No.6

<P>Sericite is mica-based natural clay that is annealed at 800 degrees C for 4 h, followed by acid activation using 3.0 mol L-1 HCl at 100 degrees C. The interaction of cesium (I), Cs(I), with sericite could provide useful data for the study of soil erosion or mass water movement utilizing the natural radioactive Cs. In this study sericite and activated sericite were used to assess their suitability in the attenuation of Cs from the aquatic environment under both batch and column experiments. The surface morphological studies indicated that a disordered and heterogeneous surface structure was exhibited by the activated sericite, whereas the native sericite exhibited a compact and layered structure. The Brunauer-Emmett-Teller (BET) specific surface area results indicated a significant increase in the surface area due to the activation of sericite. The batch reactor data collected for various parametric studies revealed that an increase in pH (from 2.0 to 8.0) and sorbate concentration (from 10.0 to 100.0 mg L-1) apparently favored the attenuation of Cs(I). The time-dependent sorption data revealed that Cs(I) uptake was very rapid, and it achieved its saturation value within just 50 min of contact. The kinetic modeling studies indicated that the uptake of Cs(I) followed a pseudo-second-order rate equation; hence, the attenuation capacity of these solids for Cs(I) was estimated to be 0.858 and 4.353 mg g(-1) for sericite and activated sericite solids, respectively. The adsorption isotherm modeling data showed a reasonably good applicability of the Freundlich model than the Langmuir model. The effect of background electrolyte concentrations (0.001 to 0.1 mol L-1) of Mg(NO3)(2) indicated that the presence of this electrolyte could not significantly affect the percent removal of Cs(I) by activated sericite. Furthermore, the fixed-bed column reactor operations were performed to obtain the breakthrough data, which were fitted well to the Thomas non-linear equation. Therefore, the loading capacity of Cs(I) was estimated to be 1.585 mg g(-1) at the initial influent Cs(I) concentration of 30.0 mg L-1 at pH 5.0.</P>

Knowledge, Attitude and Practice of Tobacco Use and Its Impact on Oral Health Status of 12 and 15 Year-Old School Children of Chhattisgarh, India

Tiwari, Ram Vinod,Megalamanegowdru, Jayachandra,Gupta, Anjali,Agrawal, Ankush,Parakh, Abhinav,Pagaria, Sulabh,Sahu, Abhishek Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.23

Background: Tobacco is a leading preventable cause of deaths worldwide; the situation is particularly serious in the developing countries. Tobacco use amongst the children and adolescents is already a pandemic and they are vulnerable targets of tobacco industry. This is also the case in India. Objectives: 1) Document and monitor the prevalence of tobacco use including smoked, smokeless and other forms of tobacco; 2) Understand student knowledge and attitudes related to tobacco use and its health impact; 3) Assess the impact of tobacco on the oral health status of school-going children in India. Materials and Methods: The sample was 1,500 school children of the age group 12-15 years age. A pretested, close ended questionnaire was administered in the form of extensive face to face interview to understand student knowledge, attitudes and behavior related to tobacco use and its health impact and to assess the prevalence of tobacco use including smoked, smokeless and other forms of tobacco. Oral health status was assessed using the Community Periodontal Index (CPI). Frequency distribution, Chi-square tests and Odd's ratio was calculated. Results: Prevalence of tobacco usage amongst the prevalence was 20.4%: 9.2% reported smoking, 15.8% used tobacco in the chewable form and 25.3% children were involved in consuming betel nut/areca nuts. The OR (Odd's ratio) for calculus formation was highest for guthka chewers (OR=14.322), paan masala chewers had the highest odds of developing bleeding on probing when compared to the others. Conclusions: There is an urgent need to launch school-based tobacco prevention programs for community awareness of children and the public, as preventing the initiation of a habit is far easier than stopping it.

Multi-item sustainable green production system under trade-credit and partial backordering

Tiwari, Sunil,Ahmed, Waqas,Sarkar, Biswajit Elsevier 2018 JOURNAL OF CLEANER PRODUCTION Vol.204 No.-

<P><B>Abstract</B></P> <P>This study develops a green production quantity model with random imperfect quality items, trade-credit policy, service level constraints, and failure in reworking. In practice, not only the green production system but also the rework process is often imperfect. The presence of a single machine in the production system outcomes in limits for green production and partial backordering. It is assumed that the green production system may generate defective items, which are reworked. As a reworked process is also not perfect, it produces a random number of scrapped items. On the other hand, the supplier also offers a trade-credit policy to the buyer, which minimizes the on-hand stock and boosts sales. In fact, this model will help organizations to minimize their costs through cooperation in industry. The objective of this research is to find the optimal green production and backordered quantity of each item such that the projected total cost is minimized. The optimal solution for each scenario is derived and the application of the designed model is validated with two numerical examples. The results for both examples show that the minimum total cost for the green production system is achieved when the permissible delay-period given by the supplier to the buyer is greater than or equal to the aggregated sum of production uptime, reworking time, production downtime, and allowed shortage time. Sensitivity analysis of the proposed study is also done to illustrate the realistic usage.</P>

Highly active and stable layered ternary transition metal chalcogenide for hydrogen evolution reaction

Tiwari, Anand P.,Kim, Doyoung,Kim, Yongshin,Prakash, Om,Lee, Hyoyoung Elsevier 2016 Nano energy Vol.28 No.-

<P><B>Abstract</B></P> <P>Layered ternary transition metal chalcogenides (TTMCs) material has great potentials that can overcome to the limitation of active sites which is challenging in binary transition metal chalcogenides (BTMC), such as MoS<SUB>2</SUB>, towards electrochemical hydrogen production. Here, we demonstrate TTMC material which contains two transition metals Cu and Mo with chalcogen S. The TTMC, Cu<SUB>2</SUB>MoS<SUB>4</SUB> has been successfully synthesized by a facile solution-processed method. Moreover, by anion doping such as Se in as the synthesized Cu<SUB>2</SUB>MoS<SUB>4</SUB>, it has been found that TTMC can be exfoliated into single layer nanosheets. Furthermore, by controlling the number of layers, single layers TTMC exhibit the highest electrocatalytic activity towards hydrogen evolution reaction (HER) because the single layers can provide more catalytic active sites than multilayers and bulk. The onset potential for hydrogen generation is −96mV for single layer TTMC electrode material with corresponding Tafel slope 52mV/decade. After 1000 cycles with continuous electrolysis in acid electrolyte for 15h, the electrode material preserves its structure and robust catalytic activity perfectly. Our new TTMC materials show highly active electrocatalytic performance and high stability which overcome the intrinsic limitation of BTMC. As a result, our work can guide new strategy for the developments of real applications of TMCs in HER.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Single layered ternary transition metal chalcogenides have been synthesized for highly active and stable electrocatalyst. </LI> <LI> Se-doping plays an essential role to exfoliate Cu<SUB>2</SUB>Mo(S<SUB>1-y</SUB>Se<SUB>y</SUB>)<SUB>4</SUB> for high electrochemical active surface. </LI> <LI> Se-doping strategy can be implemented to exfoliate and enhance electrocatalytic activity of transition metals chalcogens. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Effective approaches to synthesis of single layered ternary transition metal chalcogenide (TTMC) have been developed to produce highly active and stable electrocatalyst towards hydrogen evolution reaction. The single layered TTMC are achieved by Se-doping in Cu<SUB>2</SUB>MoS<SUB>4</SUB> which can be applicable for other transition metal chalcogenide (TMC).</P> <P>[DISPLAY OMISSION]</P>

A unified framework for operational range estimation of mobile robots operating on a single discharge to avoid complete immobilization

Tiwari, Kshitij,Xiao, Xuesu,Malik, Ashish,Chong, Nak Young Elsevier 2019 Mechatronics Vol.57 No.-

<P><B>Abstract</B></P> <P>Mobile robots are being increasingly deployed in fields where human intervention is deemed risky. However, in doing so, one of the prime concern is to prevent complete battery depletion which may in turn lead to immobilization of the robot during the mission. Thus, we need to carefully manage the energy available to explore as much of the unknown environment as feasible whilst guaranteeing a safe return journey to home base. For this, we need to identify the key components that draw energy and quantify their individual energy requirements. However, this problem is difficult due to the fact that most of the robots have different motion models, and the energy consumption usually also varies from mission to mission. It is desirable to have a generic framework that takes into account different locomotion models and possible mission profiles. This paper presents a methodology to unify the energy consumption models for various robotic platforms thereby allowing us to estimate operational range in both offline and online fashions. The existing models consider a given mission profile and try to estimate its energy requirements whilst our model considers the energy as a given resource constraint and tries to optimize the mission to be accomplished within these constraints. The proposed unified energy consumption framework is verified by field experiments for micro UGV and multi-rotor UAV test-beds operating under myriad of environmental conditions. The <I>online</I> model estimates operational range with an average accuracy (measured with respect to true range across multiple field trials) of 93.87% while the <I>offline</I> model attains 82.97%.</P>