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Bhadra, Biswa Nath,Vinu, Ajayan,Serre, Christian,Jhung, Sung Hwa Elsevier 2019 Materials today Vol.25 No.-
<P><B>Abstract</B></P> <P>Porous carbons have been considered very important for a long time because of various possible applications. In this review, we summarize the current progress in the field of porous carbons, especially N-enriched carbons, obtained from the carbonization of MOFs with or without additional N-containing compounds. Moreover, metal- or metal oxide-loaded N-doped carbons are also dealt with. Not only the preparation but also the applications in adsorption and catalysis are summarized. More importantly, research ideas or trends will be suggested for further development of these fields. Finally, this study summarizes a number of methods for the preparation of N-enriched carbons (with or without metal or metal oxide) and their efficiencies in various potential applications, including adsorption (liquid-/gas-phase) and organo-/photo-/electro-catalyses, based on their physicochemical properties.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Joghee Prasad,Arun Sekar Rajasekaran,J. Ajayan,Kambatty Bojan Gurumoorthy 한국전자통신연구원 2024 ETRI Journal Vol.46 No.4
Medical signal processing requires noise and interference-free inputs for precise segregation and classification operations. However, sensing and transmitting wireless media/devices generate noise that results in signal tampering in feature extractions. To address these issues, this article introduces a finite impulse response design based on a two-level transpose Vedic multiplier. The proposed architecture identifies the zero-noise impulse across the varying sensing intervals. In this process, the first level is the process of transpose array operations with equalization implemented to achieve zero noise at any sensed interval. This transpose occurs between successive array representations of the input with continuity. If the continuity is unavailable, then the noise interruption is considerable and results in signal tampering. The second level of the Vedic multiplier is to optimize the transpose speed for zero-noise segregation. This is performed independently for the zero- and nonzero-noise intervals. Finally, the finite impulse response is estimated as the sum of zero- and nonzero-noise inputs at any finite classification.
Sandip Bhattacharya,Mohammed Imran Hussain,John Ajayan,Shubham Tayal,Louis Maria Irudaya Leo Joseph,Sreedhar Kollem,Usha Desai,Syed Musthak Ahmed,Ravichander Janapati 한국전자통신연구원 2023 ETRI Journal Vol.45 No.5
In this study, we designed a 6T-SRAM cell using 16-nm CMOS process and analyzed the performance in terms of read-speed latency. The temperaturedependent Cu and multilayered graphene nanoribbon (MLGNR)-based nanointerconnect materials is used throughout the circuit (primarily bit/bit-bars [red lines] and word lines [write lines]). Here, the read speed analysis is performed with four different chip operating temperatures (150K, 250K, 350K, and 450K) using both Cu and graphene nanoribbon (GNR) nano-interconnects with different interconnect lengths (from 10 μm to 100 μm), for reading-0 and reading-1 operations. To execute the reading operation, the CMOS technology, that is, the16-nm PTM-HPC model, and the16-nm interconnect technology, that is, ITRS-13, are used in this application. The complete design is simulated using TSPICE simulation tools (by Mentor Graphics). The read speed latency increases rapidly as interconnect length increases for both Cu and GNR interconnects. However, the Cu interconnect has three to six times more latency than the GNR. In addition, we observe that the reading speed latency for the GNR interconnect is ~10.29 ns for wide temperature variations (150K to 450K), whereas the reading speed latency for the Cu interconnect varies between ~32 ns and 65 ns for the same temperature ranges. The above analysis is useful for the design of next generation, high-speed memories using different nano-interconnect materials.
Superior adsorption capacity of mesoporous carbon nitride with basic CN framework for phenol
Haque, Enamul,Jun, Jong Won,Talapaneni, Siddulu Naidu,Vinu, Ajayan,Jhung, Sung Hwa The Royal Society of Chemistry 2010 Journal of materials chemistry Vol.20 No.48
<p>Highly basic 2D-mesoporous carbon nitride (MCN-1) shows the highest adsorption capacity and adsorption kinetic constant for phenol due to its well ordered porous structure with the in-built basic NH and NH<SUB>2</SUB> groups on the surface, high surface area and large pore volume, suggesting the potential application of MCN-1 for the purification of contaminated water.</p> <P>Graphic Abstract</P><P>The highest adsorption capacity and kinetic constant for phenol adsorption has been achieved over mesoporous carbon nitride due to the presence of in-built basic functional groups and excellent textural parameters. <img src='http://pubs.rsc.org/ej/JM/2010/c0jm02974b/c0jm02974b-ga.gif'> </P>
Yang, Jae-Hun,Pei, Yi-Rong,Piao, Huiyan,Vinu, Ajayan,Choy, Jin-Ho The Korean Ceramic Society 2016 한국세라믹학회지 Vol.53 No.4
In this review, an attempt is made to calculate one-dimensional (1-D) electron density profiles from experimentally determined (00l) XRD intensities and possible structural models as well in an effort to understand the collective intracrystalline structures of intercalant molecules of two-dimensional (2-D) nanohybrids with heterostructures. 2-D ceramics, including layered metal oxides and clays, have received much attention due to their potential applicability as catalysts, electrodes, stabilizing agents, and drug delivery systems. 2-D nanohybrids based on such layered ceramics with various heterostructures have been realized through intercalation reactions. In general, the physico-chemical properties of such 2-D nanohybrids are strongly correlated with their heterostructures, but it is not easy to solve the crystal structures due to their low crystallinity and high anisotropic nature. However, the powder X-ray diffraction (XRD) analysis method is thought to be the most powerful means of understanding the interlayer structures of intercalant molecules. If a proper number of well-developed (00l) XRD peaks are available for such 2-D nanohybrids, the 1-D electron density along the crystallographic c-axis can be calculated via a Fourier transform analysis to obtain structural information about the orientations and arrangements of guest species in the interlayer space.
Adsorption of Phenol on Mesoporous Carbon CMK-3: Effect of Textural Properties
Enamul Haque,Nazmul Abedin Khan,Siddulu Naidu Talapaneni,Ajayan Vinu,제갈종건,정성화 대한화학회 2010 Bulletin of the Korean Chemical Society Vol.31 No.6
Mesoporous carbon CMK-3s with different textural properties have been used for the adsorption of phenol to understand the necessary physicochemical properties of carbon for the efficient removal of phenol from contaminated water. The kinetic constants (both pseudo-second order and pseudo-first-order kinetics) increase with increasing pore size of carbons. The maximum adsorption capacities correlate well with micropore volume compared with surface area or total pore volume even though large pore (meso or macropore) may contribute partly to the adsorption. The pore occupancies also explain the importance of micropore for the phenol adsorption. For efficient removal of phenol,carbon adsorbents should have large micropore volume and wide pore size for high uptake and rapid adsorption,respectively.
Composites with carbon nanotubes and graphene: An outlook
Kinloch, Ian A.,Suhr, Jonghwan,Lou, Jun,Young, Robert J.,Ajayan, Pulickel M. American Association for the Advancement of Scienc 2018 Science Vol.362 No.6414
<P>Composite materials with carbon nanotube and graphene additives have long been considered as exciting prospects among nanotechnology applications. However, after nearly two decades of work in the area, questions remain about the practical impact of nanotube and graphene composites. This uncertainty stems from factors that include poor load transfer, interfacial engineering, dispersion, and viscosity-related issues that lead to processing challenges in such nanocomposites. Moreover, there has been little effort to identify selection rules for the use of nanotubes or graphene in composite matrices for specific applications. This review is a critical look at the status of composites for developing high-strength, low-density, high-conductivity materials with nanotubes or graphene. An outlook of the different approaches that can lead to practically useful nanotube and graphene composites is presented, pointing out the challenges and opportunities that exist in the field.</P>
A review: controlled synthesis of vertically aligned carbon nanotubes
Myung-Gwan Hahm,Daniel P. Hashim,Robert Vajtai,Pulickel M. Ajayan 한국탄소학회 2011 Carbon Letters Vol.12 No.4
Carbon nanotubes (CNTs) have developed into one of the most competitively researched nano-materials of this decade because of their structural uniqueness and excellent physical properties such as nanoscale one dimensionality, high aspect ratio, high mechanical strength, thermal conductivity and excellent electrical conductivity. Mass production and structure control of CNTs are key factors for a feasible CNT industry. Water and ethanol vapor enhance the catalytic activity for massive growth of vertically aligned CNTs. A shower system for gas flow improves the growth of vertically aligned single walled CNTs (SWCNTs) by controlling the gas flow direction. Delivery of gases from the top of the nanotubes enables direct and precise supply of carbon source and water vapor to the catalysts. High quality vertically aligned SWCNTs synthesized using plasma enhance the chemical vapor deposition technique on substrate with suitable metal catalyst particles. This review provides an introduction to the concept of the growth of vertically aligned SWCNTs and covers advanced topics on the controlled synthesis of vertically aligned SWCNTs.
Layer-by-Layer Films of Dual-Pore Carbon Capsules with Designable Selectivity of Gas Adsorption
Ji, Qingmin,Yoon, Suk Bon,Hill, Jonathan P.,Vinu, Ajayan,Yu, Jong-Sung,Ariga, Katsuhiko American Chemical Society 2009 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.131 No.12
<P>Stable, homogeneous ultrathin films of uniformly dimensioned dual-pore carbon capsules with mesoporous walls and macroscopic empty cores were fabricated using layer-by-layer methods based on electrostatic interaction between a polyelectrolyte and a surfactant coating of the carbon capsules. The resulting dual-porous carbon capsule films were investigated as a sensor substrate for vapors of different organic solvents. The carbon capsule films have much higher adsorption capacities than conventional electrolyte films and even than noncapsular mesoporous carbon films. The dual-pore carbon capsules have greater affinities for aromatic volatiles over their aliphatic counterparts, probably due to stronger pi-pi interactions. Additionally, the adsorption selectivity can be designed. Impregnation of additional recognition components into the carbon capsules permits further control over adsorption selectivity between aromatic and nonaromatic substances and between acids and bases in the prevailing atmosphere. Therefore, it is anticipated that the dual-pore carbon capsule films developed in this work will find application in sensing and separation applications because of their designable selectivity.</P>