A NOTE ON GENERALIZED DERIVATIONS AS A JORDAN HOMOMORPHISMS

Chandrasekhar, Arusha,Tiwari, Shailesh Kumar Korean Mathematical Society 2020 대한수학회보 Vol.57 No.3

Let R be a prime ring of characteristic different from 2. Suppose that F, G, H and T are generalized derivations of R. Let U be the Utumi quotient ring of R and C be the center of U, called the extended centroid of R and let f(x₁, …, x_n) be a non central multilinear polynomial over C. If F(f(r₁, …, r_n))G(f(r₁, …, r_n)) - f(r₁, …, r_n)T(f(r₁, …, r_n)) = H(f(r₁, …, r_n)²) for all r₁, …, r_n ∈ R, then we describe all possible forms of F, G, H and T.

Room temperature solution-processed Fe doped NiOx as a novel hole transport layer for high efficient perovskite solar cells

Chandrasekhar, P.S.,Seo, You-Hyun,Noh, Yong-Jin,Na, Seok-In Elsevier 2019 APPLIED SURFACE SCIENCE - Vol.481 No.-

<P><B>Abstract</B></P> <P>Perovskite solar cells (PSCs) represent a pivotal change in photovoltaics and are emerging as one of the most promising solar cell technologies for highly efficient and cost-effective solar energy production. In PSCs, the hole transport layer (HTL) plays a significant role in achieving high efficiency by improving charge collection and reducing recombination losses at the interface of the HTL/perovskite. Herein, we present a detailed investigation of the photovoltaic performance of PSCs by employing Fe-doped NiOx nanoparticles (NPs) as HTL. A simple solution method is adopted to synthesize Fe-doped NiOx NPs and their corresponding films are deposited by spin coating using Fe-NiOx inks at room temperature without any post treatment. As the obtained Fe-doped NiOx films exhibited an improvement in conductivity and work function, they resulted in an improvement in hole extraction and charge collection, while suppressing the charge recombination. Consequently, Fe-NiOx-based devices provided a significant enhancement in power conversion efficiency (PCE) of 17.57% compared to pristine NiOx of 15.41%. Flexible PSCs also showed an improvement in PCE from 13.37% for pristine NiOx to 14.42% for Fe-NiOx NPs. This work demonstrates that Fe-doped NiOx can be a promising HTL for fabricating highly efficient and flexible PSC production in the future.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Fe-doped NiOx nanoparticles have been studied in perovskite solar cells as a hole transport layer. </LI> <LI> Fe-NiOx based devices have significantly improved power conversion efficiency up to 17.57%. </LI> <LI> In the flexible PSCs, PCE of 14.42% for Fe-NiOx is obtained. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Human Interactive Triboelectric Nanogenerator as a Self-Powered Smart Seat

Chandrasekhar, Arunkumar,Alluri, Nagamalleswara Rao,Saravanakumar, Balasubramaniam,Selvarajan, Sophia,Kim, Sang-Jae American Chemical Society 2016 ACS APPLIED MATERIALS & INTERFACES Vol.8 No.15

<P>A lightweight, flexible, cost-effective, and robust, single-electrode-based Smart Seat Triboelectric Nano generator (SS-TENG) is introduced as a promising eco-friendly approach for harvesting energy from the living environment, for use in integrated self-powered systems. An effective method for harvesting biomechanical energy from human motion such as walking, running, and sitting, utilizing widely adaptable everyday contact materials (newspaper, denim, polyethylene covers, and bus cards) is demonstrated. The working mechanism of the SS-TENG is based on the generation and transfer of triboelectric charge carriers between the active layer and user-friendly contact materials. The performance of SS-TENG (52 V and 5.2 mu A for a multiunit SS-TENG) is systematically studied and demonstrated in a range of applications including a self-powered passenger seat number indicator and a STOP-indicator using LEDs, using a simple logical circuit. Harvested energy is used as a direct power source to drive 60 blue and green commercially available LEDs and a monochrome LCD. This feasibility study confirms that triboelectric nanogenerators are a suitable technology for energy harvesting from human motion during transportation, which could be used to operate a variety of wireless devices, GPS systems, electronic devices, and other sensors during travel.</P>

Biohydrogen Production: Strategies to Improve Process Efficiency through Microbial Routes

Chandrasekhar, Kuppam,Lee, Yong-Jik,Lee, Dong-Woo MDPI 2015 INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES Vol.16 No.4

<P>The current fossil fuel-based generation of energy has led to large-scale industrial development. However, the reliance on fossil fuels leads to the significant depletion of natural resources of buried combustible geologic deposits and to negative effects on the global climate with emissions of greenhouse gases. Accordingly, enormous efforts are directed to transition from fossil fuels to nonpolluting and renewable energy sources. One potential alternative is biohydrogen (H<SUB>2</SUB>), a clean energy carrier with high-energy yields; upon the combustion of H<SUB>2</SUB>, H<SUB>2</SUB>O is the only major by-product. In recent decades, the attractive and renewable characteristics of H<SUB>2</SUB> led us to develop a variety of biological routes for the production of H<SUB>2</SUB>. Based on the mode of H<SUB>2</SUB> generation, the biological routes for H<SUB>2</SUB> production are categorized into four groups: photobiological fermentation, anaerobic fermentation, enzymatic and microbial electrolysis, and a combination of these processes. Thus, this review primarily focuses on the evaluation of the biological routes for the production of H<SUB>2</SUB>. In particular, we assess the efficiency and feasibility of these bioprocesses with respect to the factors that affect operations, and we delineate the limitations. Additionally, alternative options such as bioaugmentation, multiple process integration, and microbial electrolysis to improve process efficiency are discussed to address industrial-level applications.</P>

A microcrystalline cellulose ingrained polydimethylsiloxane triboelectric nanogenerator as a self-powered locomotion detector

Chandrasekhar, A.,Alluri, N.,Saravanakumar, B.,Selvarajan, S.,Kim, S. J. Royal Society of Chemistry 2017 Journal of materials chemistry. C, Materials for o Vol.5 No.7

<P>Scavenging of ambient dissipated mechanical energy addresses the limitations of conventional batteries by providing an auxiliary voltaic power source, and thus has significant potential for self-powered and wearable electronics. Here, we demonstrate a cellulose/polydimethylsiloxane (PDMS) triboelectric nanogenerator (C-TENG) based on the contact and separation mode between a cellulose/PDMS composite film and an aluminium electrode. The device fabricated with a composite film of 5 wt% generates an open circuit voltage of 28 V and a short circuit current of 2.8 mu A with an instantaneous peak power of 576 mu W at a mechanical force of 32.16 N. The C-TENG was systematically studied and demonstrated to be a feasible power source that can commute instantaneous operation of LEDs and act as a self-powered locomotion detector for security applications. The C-TENG can also be used as a wearable power source with an in-built lithium ion battery charging circuit during a range of human motions.</P>

A fully packed spheroidal hybrid generator for water wave energy harvesting and self-powered position tracking

Chandrasekhar, Arunkumar,Vivekananthan, Venkateswaran,Kim, Sang-Jae Elsevier 2020 Nano energy Vol.69 No.-

<P><B>Abstract</B></P> <P>Water waves are a promising source of renewable energy. Their kinetic energy can potentially drive energy harvesters. Herein, we describe a fully packed spheroidal smart buoy hybrid generator (SB-HG) composed of triboelectric nanogenerator (TENG) and an electromagnetic generator (EMG) for scavenging water-wave energy. Each of the energy harvesting components generated electrical outputs from the same wave motion. A position-tracking long-range (LoRa) device placed in the buoy enabled identification of the buoy location when it was placed in the sea for energy harvesting, navigation, and fishnet tracking purposes. A solar cell placed on the top of the buoy powered the device under calm wave conditions. The TENG and EMG components generated maximum electrical outputs of 100 V/2 μA and 20 V/15 mA, respectively. Combining the devices efficiently converted the kinetic energy of the waves into useful electrical energy, which was used to charge a commercial capacitor and lithium-ion battery. The charged battery drove the position-tracking LoRa device for a positioning application and demonstrated that the SB-HG device is an inexpensive and reliable candidate for ocean navigation systems. Our water-wave energy harvester is highly promising as a clean energy power source and as a self-powered sensor for various environmental monitoring systems.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A smart buoy hybrid generator is made of TENG-EMG omponents which can be driven by water waves. </LI> <LI> The electrical output of the device is greatly enhanced due to the hybrid configuration. </LI> <LI> The device is made as a scalable and multi-unit device for the enhanced energy harvesting capability in a single device. </LI> <LI> The device is used as a self-powered position tracking by using a LoRa module and interface with mobile phone application. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

A sustainable freestanding biomechanical energy harvesting smart backpack as a portable-wearable power source

Chandrasekhar, A.,Alluri, N.,Vivekananthan, V.,Purusothaman, Y.,Kim, S. J. Royal Society of Chemistry 2017 Journal of Materials Chemistry C Vol.5 No.6

<P>Wearable gadgets have attracted consumer attention, resulting in an abundance of research on the development of self-powered devices. Recently, triboelectric nanogenerators (TENGs) have been shown to be an effective approach for scavenging biomechanical energy. An innovative, cost-effective and eco-friendly freestanding smart backpack-triboelectric nanogenerator (SBP-TENG) is presented for scavenging biomechanical energy. A new approach to creating irregular surfaces on a polydimethylsiloxane (PDMS) film is demonstrated by recycling a plastic Petri dish discarded after laboratory usage. The SBP-TENG relies on contact and separation electrification between the PDMS film and contact materials (wool, paper, cotton, denim and polyethylene). The performance of single-and multi-unit SBP-TENGs is systematically studied and real-time energy harvesting from human motions, such as walking, running and bending, is demonstrated. This study confirms that the SBP-TENG is an excellent technology for scavenging biomechanical energy, capable of driving a variety of low-power electronic devices such as global positioning system (GPS) sensors, wearable sensors and flashlights.</P>

Effectiveness of piggery waste treatment using microbial fuel cells coupled with elutriated-phased acid fermentation

Chandrasekhar, K.,Ahn, Young-Ho Elsevier 2017 Bioresource technology Vol.244 No.1

<P><B>Abstract</B></P> <P>The present study evaluates the feasibility of increased power generation in microbial fuel cells (MFCs) coupled with acid elutriation fermentation. Raw piggery waste (RPW) and acid elutriation effluents (AEE) of piggery waste were used to generate bioelectricity in single-chambered air–cathode MFCs. RPW-fed MFCs exhibited stable performance after 12-days of operation, generating 540mV of open circuit voltage (OCV). RPW fed-MFCs displayed peak potential and maximal power density (PD<SUB>max</SUB>) of 0.364V and 192mW/m<SUP>2</SUP> with 980Ω external resistance (R<SUB>ext</SUB>), respectively. AEE-fed MFCs documented 818mV of maximum OCV. Furthermore, the peak potential and PD<SUB>max</SUB> of 0.329V and 1553mW/m<SUP>2</SUP> were generated with 100Ω R<SUB>ext</SUB>, respectively. RPW and AEE-fed MFCs exhibited 84% and 93% substrate removal efficiency, respectively. These findings suggest that a two-stage process including acid elutriation reactor asa pre-fermentation and MFCs greatly enhances substrate removal and electricity generation from piggery waste.</P> <P><B>Highlights</B></P> <P> <UL> <LI> MFCs coupled with acid elutriation fermenter for enhanced bioelectricity generation. </LI> <LI> Piggery waste-fed acid elutriation fermenter generated more organic acids at pH 9. </LI> <LI> The power generation was improved with acid elutriation fermenter effluents. </LI> <LI> The maximum power density achieved is 1553mW/m<SUP>2</SUP> in AEE-fed MFCs. </LI> <LI> Process configuration for both waste treatment and continuous bioelectrogenesis. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

A smart mobile pouch as a biomechanical energy harvester towards self-powered smart wireless power transfer applications

Chandrasekhar, A.,Alluri, N.,Sudhakaran, M. S.,Mok, Y.,Kim, S. J. Royal Society of Chemistry 2017 Nanoscale Vol.9 No.28

Buoyancy Induced Flows in Spherical Annular Sectors of Small Angle

Chandrasekhar Thamire,Neil T. Wright 대한기계학회 1998 Heat transter conference Vol.3 No.1