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Enhancing sintering resistance of atomically dispersed catalysts in reducing environments with organic monolayers

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Green Energy & Environment 2022年第6期7卷 1263-1269页

作者： Jing Zhang chithra Asokan Gregory Zakem Phillip Christopher J.Will Medlin Department of Chemical and Biological Engineering University of ColoradoBoulderCOUSA Department of Chemical Engineering University of CaliforniaSanta BarbaraSanta BarbaraCAUSA

Atomically dispersed precious metal catalysts maximize atom efficiency and exhibit unique ***,they are susceptible to *** reactions occurring in reducing environments tend to result in atomically dispersed metals sintering at lower temperatures than in oxidative or inert atmospheres due to the formation of mobile metal-H or metal-CO ***,we develop a new approach to mitigate sintering of oxide supported atomically dispersed metals in a reducing atmosphere using organophosphonate self-assembled monolayers(SAMs).We demonstrate this for the case of atomically dispersed Rh on Al_(2)O_(3) and TiO_(2) using a combination of CO probe molecule FTIR,temperature programmed desorption,and alkene hydrogenation rate *** suggests that SAM functionalization of the oxide provides physical diffusion barriers for the metal and weakens the interactions between the reducing gas and metal,thereby discouraging the adsorbate-promoted diffusion of metal atoms on oxide *** results show that support functionalization by organic species can provide improved resistance to sintering of atomically dispersed metals with maintained catalytic reactivity.

关键词： Atomically dispersed catalysts Organic monolayers Rh Single atom catalysis Sintering

Energy Proficient Reduced Coverage Set with Particle Swarm Optimization for Distributed Sensor Network

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Computer Systems Science & Engineering 2023年第5期45卷 1611-1623页

作者： T.V.chithra A.Milton Department of Computer Science and Engineering Arunachala College of Engineering for WomenManavilaiTamil Nadu629203India Department of Electronics and Communication Engineering St.Xavier’s Catholic College of EngineeringChunkankadaiTamil Nadu629003India

Retransmission avoidance is an essential need for any type of wireless *** retransmissions induce the unnecessary presence of redundant data in every accessible *** storage capacity is symmetrical to the size of the memory,less storage capacity is experienced due to the restricted size of the respective *** this proposed work,we have discussed the integration of the Energy Proficient Reduced Coverage Set with Particle Swarm Optimization(PSO).PSO is a metaheuristic global search enhancement technique that promotes the searching of the best nodes in the search *** is integrated with a Reduced Coverage Set,to obtain an optimal path with only high-power transmitting *** Proficient Reduced Coverage Set with PSO constructs a set of only best nodes based on the fitness solution,to cover the whole *** proposed algorithm has experimented with a different number of *** has been made between original and improved algorithm shows that improved algorithm performs better than the existing by reducing the redundant packet transmissions by 18%~40%,thereby increasing the network lifetime.

关键词： Wireless sensor network reduced coverage set swarm intelligence particle swarm optimization energy consumption

High Throughput Scheduling Algorithms for Input Queued Packet Switches

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Computers, Materials & Continua 2022年第1期70卷 1527-1540页

作者： R.chithra Devi D.Jemi Florinabel Narayanan Prasanth Department of IT Dr.Sivanthi Aditanar College of EngineeringTiruchendur628205India Department of CSE Dr.Sivanthi Aditanar College of EngineeringTiruchendur628205India School of CSE Vellore Institute of TechnologyVellore632014India

The high-performance computing paradigm needs high-speed switching fabrics to meet the heavy traffic generated by their *** switching fabrics are efficiently driven by the deployed scheduling *** this paper,we proposed two scheduling algorithms for input queued switches whose operations are based on ranking *** first,we proposed a Simple 2-Bit(S2B)scheme which uses binary ranking procedure and queue size for scheduling the ***,the Virtual Output Queue(VOQ)set with maximum number of empty queues receives higher rank than other VOQ’*** simulation,we showed S2B has better throughput performance than Highest Ranking First(HRF)arbitration under uniform,and non-uniform traffic *** further improve the throughput-delay performance,an Enhanced 2-Bit(E2B)approach is *** approach adopts an integer representation for rank,which is the number of empty queues in a VOQ *** simulation result shows E2B outperforms S2B and HRF scheduling algorithms with maximum throughput-delay ***,the algorithms are simulated under hotspot traffic and E2B proves to be more efficient.

关键词： Crossbar switch input queued switch virtual output queue scheduling algorithm high performance computing

An Improved Pairing-Free Ciphertext Policy Framework for IoT

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Computer Systems Science & Engineering 2023年第6期45卷 3079-3095页

作者： M.Amirthavalli S.chithra R.Yugha Department of Information Technology Sri Sivasubramaniya Nadar College of EngineeringRajiv Gandhi Salai(OMR)Kalavakkam603110Tamil NaduIndia

Internet of Things(IoT)enables devices to get connected to the *** they are connected,they behave as smart devices thereby releasing sensitive data *** is a necessity to preserve the confidentiality and integrity of this data during transmission in public communication channels and also permitting only legitimate users to access their data A key challenge of smart networks is to establish a secure end-to-end data communication architecture by addressing the security vulnerabilities of data users and smart *** objective of this research work is to create a framework encompassing Ciphertext policy Attribute-based Encryption scheme using block encryption and BLAKE hashing *** improved Pairing-Free-Ciphertext policy Attribute-based encryption algorithm has been developed to overcome the aforementioned ***,a comparative study has been performed between the proposed scheme and the different encryption *** is found that the proposed scheme scores well over the already existing *** scheme is evaluated in terms of execution time and communication *** robustness of the proposed scheme is also analyzed from the perspective of several security goals.

关键词： Internet of things access control cipher policy based-attribute based encryption(CP-ABE) access matrix performance analysis

Effect of pH on Crystal Size and Photoluminescence Property of ZnO Nanoparticles Prepared by Chemical Precipitation Method

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Acta Metallurgica Sinica(English Letters) 2015年第3期28卷 394-404页

作者： M.Jay chithra M.Sathya K.Pushpanathan PG & Research Department of Physics Government Arts College

The effects of pH value on crystal size and optical property of zinc oxide nanoparticles prepared by chemical precipitation method were *** samples have been characterized by means of X-ray diffraction,scanning electron microscopy,ultraviolet-visible spectrometer and photoluminescence *** X-ray diffraction profile,it is found that the particle size of sample increases from 13.8 to 33 nm when the pH value of the solution was increased from 6 to *** study also shows that the particle size increases with pH *** shape of the zinc oxide nanoparticle has been confirmed by the scanning electron microscopy *** recorded ultraviolet-visible spectrum shows excitonic absorption peaks around 381 *** energy gap of the prepared samples has been determined from the ultraviolet-visible absorption spectrum,effective mass model equation and Tauc＇s *** was found that the energy gap of the prepared samples decreases with increase in pH *** recorded blue shift confirmed the quantum confinement effect in the prepared zinc oxide *** spectrum infers that the increase in pH value shifts the ultraviolet-visible emission but not the violet and green emissions.

关键词： Zinc oxide nanoparticles pH value Crystal structure Microstructure Energy gap Photoluminescence

Lithium ion conduction and ion-polymer interaction in poly(vinyl pyrrolidone) based electrolytes blended with different plasticizers

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Chinese Chemical Letters 2014年第11期25卷 1428-1434页

作者： K.Kesavan chithra M.Mathew S.Rajendran School of Physics Alagappa University

Poly（ethylene oxide）, poly（vinyl pyrrolidone）（PEO/PVP）, lithium perchlorate salt（Li Cl O4） and different plasticizer based, gel polymer electrolytes were prepared by the solvent casting technique. XRD results show that the crystallinity decreases with the addition of different plasticizers. Consequently, there is an enhancement in the amorphousity of the samples responsible for the process of ion transport. FTIR spectroscopy is used to characterize the structure of the polymer and confirms the complexation of plasticizer with host polymer matrix. The ionic conductivity has been calculated using the bulk impedance obtained through impedance spectroscopy. Among the various plasticizers, the ethylene carbonate（EC） based complex exhibits a maximum ionic conductivity value of the order of2.7279 10 4S cm 1. Thermal stability of the prepared electrolyte films shows that they can be used in batteries at elevated temperatures. PEO（72%）/PVP（8%）/Li Cl O4（8%）/EC（12%） has the maximum ionic conductivity value which is supported by the lowest optical band gap and lowest intensity in photoluminescence spectroscopy near 400–450 nm. Two and three dimensional topographic images of the sample having a maximum ionic conductivity show the presence of micropores.

关键词： Polymers Thermogravimetric analysis(TGA) X-ray diffraction Luminescence Transport properties

Sprouted Sorghum Extract Elicits Coleoptile Emergence, Enhances Shoot and Root Acclimatization, and Maintains Genetic Fidelity in indica Rice

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Rice science 2018年第2期25卷 61-72页

作者： Subramanian Radhesh KRISHNAN Pandiyan MUTHURAMALINGAM Subramani PANDIAN Ramachandradoss BANUPRIYA Gunasekar chithra Manikandan RAMESH Department of Biotechnology Alagappa University Karaikudi 630004 Tamilnadu India T. Stanes & Company Limited Coimbatore 641018 India

The high growth-stimulating effect of plant extract has urged the plant biotechnologists to use natural supplements in the culture media instead of synthetic phytohormones. We advocated the effect of sprouted sorghum extract(SSE) on emergence, in vitro acclimatization, and genetic fidelity in coleoptile derived callus of indica rice variety ADT36. The use of SSE with Murashige Skoog medium efficiently acclimatized the root and shoot apical systems. A higher mat and seminal roots(3.4 g biomass) with an efficient shoot primordium elongation were observed with an increase in the concentration of SSE. Seeds treated with SSE medium showed higher germination and earlier coleoptile maturation about 48 h compared to untreated seeds, and there was a higher expression of e EF-1α with an increase in coleoptile length. B5 medium was effective on inducing embryogenic and nodular callus from 3-day-old coleoptile with 3.0 mg/L 2,4-dichlorophenoxyacetic acid and further proliferated effectively with 0.8 mg/L kinetin with a fresh weight of 180 mg. Highly significant regeneration was observed with combination of 2.5 mg/L 6-benzylamino purine and 3.0 mg/L α-naphthaleneacetic acid. The metabolic and genetic profiles of in vitro and directly cultivated plants were the same, examined through Fourier-transform infrared spectroscopy, random amplified polymorphic DNA(RAPD), inter-simple sequence repeat(ISSR) and R-ISSR(combination of RAPD and ISSR) markers, respectively, and thus confirming the significant efficacy of the SSE incorporated medium. Disarmed T-DNA was transformed to coleoptile derived callus through Agrobacterium tumefaciens LBA4404 and confirmed by GUS assay. The T-DNA integration was confirmed by DNA blot analysis using DNA from transient GUS-expressed explants. Thus, SSE can be used as a natural and organic supplement for organogenesis and efficient acclimatizations of shoot and root apical meristems in regenerated plants.

关键词： callus induction coleoptile Oryza sativa random amplified polymorphic DNA inter-simple sequence repeat regeneration tissue culture

利用探针分子红外光谱识别和表征铂族金属基单原子催化剂（英文）

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Chinese Journal of Catalysis 2017年第9期38卷 1473-1480页

作者： chithra Asokan Leo DeRita Phillip Christopher 加利福尼亚大学河滨分校化工与环境工程系加利福尼亚大学河滨分校材料科学项目加利福尼亚大学河滨分校催化UCR中心

单原子催化是提高贵金属利用率的有效手段,而表征单原子催化剂是理解单原子催化的基础.探针分子红外光谱可用于识别和定量催化剂样品中孤立的Pt族金属物种的浓度,从而得到负载的孤立的Pt族金属物种的局部几何形状、稳定性、活性及其分散... 详细信息

单原子催化是提高贵金属利用率的有效手段,而表征单原子催化剂是理解单原子催化的基础.探针分子红外光谱可用于识别和定量催化剂样品中孤立的Pt族金属物种的浓度,从而得到负载的孤立的Pt族金属物种的局部几何形状、稳定性、活性及其分散性.本文讨论了该技术用于识别和表征含负载型孤立的Pt族金属原子催化剂的效能、应用、以及未来的发展方向.

关键词：单原子催化剂铂族金属红外光谱表征载体效应

Structural,Dielectric,and Magnetic Studies on Electrospun Magnesium Ferrite-Polyvinylidene Fluoride Core–Shell Composite Fibers

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Acta Metallurgica Sinica(English Letters) 2014年第4期27卷 557-562页

作者： V.Revathi S.Dinesh Kumar P.chithra Lekha V.Subramanian T.S.Natarajan C.Muthamizhchelvan New Horizon College of Engineering Bangalore 560103India Microwave Laboratory Department of PhysicsIIT MadrasChennai 600036India SRM University KattankulathurChennai 603203India

The sub-micron（of the order of 150 nm） thick core–shell composite fibers of magnesium ferrite-polyvinylidene fluoride are prepared by *** loading of magnesium ferrite is varied from 1 to 10 wt%.The study results by X-ray diffraction,scanning electron microscope,and infra-red spectroscopy indicate the formation of core–shell structure and an enhancement in the amount of b-phase compared to a-phase in the polyvinylidene *** particle size of the magnesium ferrite in the fiber is evaluated to be 30 *** low frequency dielectric studies indicate that the addition of the magnesium ferrite increases the polarization resulting in the increase in the dielectric constant but decreases the dielectric *** magnetization measurements indicate an increased value of coercivity compared to bulk due to the nano-size of the magnesium *** microwave absorption at the ferromagnetic resonance increases with the increase in the concentration of magnesium *** resonance field is found to vary with the loading of MFO.

关键词： Electrospinning Polymer composites Dielectric properties Magnetic properties X-ray diffraction(XRD) Microwave absorption