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排序方式: 共有326条查询结果,搜索用时 203 毫秒
201.
V. Vignesh M. K. V. Karthikeyan 《International Journal of Polymer Analysis and Characterization》2017,22(7):610-621
The research article focused on the effect of wood sawdust as secondary filler reinforcement in Indian mallow fiber yarn mat reinforced with polyester composites. Composites were fabricated along the transverse and longitudinal orientation in six different combinations by compression molding machine. The mechanical properties of composites by single and double layer yarn mat with and without wood sawdust filler were evaluated while loading composites specimen on warp and weft direction at the first time in this research paper. The Indian mallow fiber double layer longitudinal orientation yarn mat/wood sawdust filler/polyester composite specimen along the warp direction was found to exhibit optimum mechanical properties compared to other composites. Furthermore, the Indian mallow fiber yarn mat composites were fabricated with helmet and civil construction pipes at first time in this work to replace the synthetic fiber through natural fiber. Scanning electron microscopy was performed to study the morphologies of internal crack and fractured surface of composites. 相似文献
202.
Effect of Erbium on the Photocatalytic Activity of TiO2/Ag Nanocomposites under Visible Light Irradiation
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Natarajan Prakash Rajan Karthikeyan Dr. Dheivasigamani Thangaraju Dr. Mani Navaneethan Dr. Mukannan Arivanandhan Tadanobu Koyama Prof. Yasuhiro Hayakawa 《Chemphyschem》2015,16(14):3084-3092
Erbium co‐doped TiO2/Ag catalysts are synthesized by using a simple, one‐step solvothermal method and characterized by X‐ray diffraction, field‐emission scanning electron microscopy, transmission electron microscopy, Raman analysis, X‐ray photoelectron spectroscopy, and diffuse reflectance spectroscopy. The catalysts exhibit anatase crystal structures with increased visible light absorption compared with pure TiO2. Enhanced photocatalytic activity is observed with Er co‐doped TiO2/Ag nanocomposites for Rhodamine B degradation under visible light irradiation. The photocatalytic activity of 1 % Er co‐doped TiO2/Ag is much higher than that of TiO2/Ag, TiO2/Er, pure TiO2, and commercial Degussa P25. The kinetics of the degradation process are studied and the pseudo‐first‐order rate constant (k) and half‐life time (t1/2) of the reaction are calculated. The enhanced activity might be accredited to the efficient separation of electron–hole pairs by silver and higher visible light absorption of TiO2 induced by Er. 相似文献
203.
Karthikeyan B 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2007,66(4-5):860-862
Copper doped sodium leadbismuthate glasses were prepared in the chemical composition (wt.%) 35Bi2O3+35PbO+(30-x)Na2O+xCuO (where x=1, 2, 3 and 4). The optical spectra of the glasses have been investigated. The optical absorption spectra of Cu2+ doped glasses show a broad absorption band between 560 and 880 nm, which is attributed to the 2Eg-->2T2g transition of Cu2+ ion. FTIR spectral studies confirm the Bi-O bonds and the presence of [BiO3] pyramidal units. 相似文献
204.
Controlling chaos and supressing chimeras in a fractional-order discrete phase-locked loop using impulse control
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Karthikeyan Rajagopal Anitha Karthikeyan and Balamurali Ramakrishnan 《中国物理 B》2021,30(12):120512-120512
A fractional-order difference equation model of a third-order discrete phase-locked loop (FODPLL) is discussed and the dynamical behavior of the model is demonstrated using bifurcation plots and a basin of attraction. We show a narrow region of loop gain where the FODPLL exhibits quasi-periodic oscillations, which were not identified in the integer-order model. We propose a simple impulse control algorithm to suppress chaos and discuss the effect of the control step. A network of FODPLL oscillators is constructed and investigated for synchronization behavior. We show the existence of chimera states while transiting from an asynchronous to a synchronous state. The same impulse control method is applied to a lattice array of FODPLL, and the chimera states are then synchronized using the impulse control algorithm. We show that the lower control steps can achieve better control over the higher control steps. 相似文献
205.
Muthian Shanmugasundaram Raghavachary Raghunathan Ezekiel J. Padma Malar 《Heteroatom Chemistry》1998,9(5):517-522
Synthesis of a series of novel 1,3,2′-triphenyl-4-aryl spiropyrazolines [5.4′]-2′-butenolides has been accomplished in good yield by regioselective 1,3-dipolar cycloaddition of diphenylnitrilimine with (E)-3-arylidenebutenolides. X-ray crystal structure analysis of one of the products 4a confirms the structure of the product and the regiochemistry of cycloaddition. © 1998 John Wiley & Sons, Inc. Heteroatom Chem 9:517–522, 1998 相似文献
206.
The feasibility of using two different microwave-based sample preparation methods was investigated to determine the total and water-soluble trace metal fraction in airborne particulate matter. The extraction techniques were then applied to urban particulate matter of different sizes in order to evaluate their bioavailability of associated trace metals. While a combination of HNO3-HF-H2O2 was used for the total trace metal fraction of particulate matter, water was employed for the microwave-assisted extraction of water-soluble trace metal fractions. Inductively coupled plasma-mass spectrometry (ICP-MS) was used for the analysis of trace elements. The experimental protocol for the microwave assisted digestion was established using two different SRMs (1648, urban particulate matter and 1649a, urban dust). In the case of water-soluble trace metal fraction, the quantities extracted from the SRMs were compared between ultrasonic and microwave-assisted extractions, and there was a good agreement between the two extraction methods. Blanks values and limits of detection (LODs) for total and water-soluble trace metal concentrations were determined for three different filter substrates (Teflon, Zeflour, and Quartz). Subsequently, the proposed digestion method was evaluated for its extraction efficiency with these filter substrates. Finally, the real-world application of the proposed microwave-based sample preparation methods was demonstrated by analyzing trace elements in airborne particulate samples collected from different outdoor environments in Singapore. The solubility of 11 trace elements detected in the particulate samples is quantified. 相似文献
207.
Rajagopal Karthikeyan Hasanzadeh Navid Parastesh Fatemeh Hamarash Ibrahim Ismael Jafari Sajad Hussain Iqtadar 《Nonlinear dynamics》2020,101(1):711-718
Nonlinear Dynamics - The outbreak of the novel coronavirus (COVID-19), which was firstly reported in China, has affected many countries worldwide. To understand and predict the transmission... 相似文献
208.
Manish Kumar Mishra Samiksha Kukal Priyanka Rani Paul Shivangi Bora Anju Singh Shrikant Kukreti Luciano Saso Karthikeyan Muthusamy Yasha Hasija Ritushree Kukreti 《Molecules (Basel, Switzerland)》2022,27(1)
Valproic acid (VPA) is a well-established anticonvulsant drug discovered serendipitously and marketed for the treatment of epilepsy, migraine, bipolar disorder and neuropathic pain. Apart from this, VPA has potential therapeutic applications in other central nervous system (CNS) disorders and in various cancer types. Since the discovery of its anticonvulsant activity, substantial efforts have been made to develop structural analogues and derivatives in an attempt to increase potency and decrease adverse side effects, the most significant being teratogenicity and hepatotoxicity. Most of these compounds have shown reduced toxicity with improved potency. The simple structure of VPA offers a great advantage to its modification. This review briefly discusses the pharmacology and molecular targets of VPA. The article then elaborates on the structural modifications in VPA including amide-derivatives, acid and cyclic analogues, urea derivatives and pro-drugs, and compares their pharmacological profile with that of the parent molecule. The current challenges for the clinical use of these derivatives are also discussed. The review is expected to provide necessary knowledgebase for the further development of VPA-derived compounds. 相似文献
209.
Kanakarajan Vijayakumari Rakhesh Sunkarankutty Nair Ashalatha Karthikeyan Mahima Venkidasamy Baskar Muthu Thiruvengadam 《Molecules (Basel, Switzerland)》2022,27(9)
Plants thrive under abiotic and biotic stress conditions with the changes in phytohormones like salicylic acid (SA), resulting in the synthesis of secondary metabolites. The present study determines the response of plants in producing secondary metabolites towards different SA concentrations at varying time intervals. Liquid chromatography-mass spectrometry-based metabolomics studies in Aphanamixis polystachya (Wall.) Parker seedlings are grown at 10 mM, 50 mM, and 100 mM SA concentrations, showed the differential expression of metabolites towards the stress. Alkaloids like amaranthin showed a 15-fold increase on the second day, and analog of androvinblastin showed a 20-fold increase on the sixth day in 10 mM SA compared with other groups. Flavanoid cyanidin 3-3 glucosyl was found to be with a 22-fold increment along with terpenoids betavulgaroside (18-fold), asiaticoside (17-fold), mubenin B (20-fold), and deslanoside (22-fold) increment in 50 mM SA on the sixth day. The shock exerted by 100 mM was too harsh, and the lowered metabolite production level was insufficient for the seedlings to survive at this higher SA condition. Arrangement of stressed groups using Pearson correlation studies, principal component analysis, and partial least square analysis placed 10 mM SA and controlled group closer and 50 mM SA and 100 mM SA groups closer to each other. The study observed that SA regulates metabolites that mediate biotic stress responses at low concentrations, and higher concentrations regulate abiotic stress regulating metabolites. 相似文献
210.
Selvaraj Sureshkumar Shanmugasundaram Suguna Maruthamuthu Murugan Venkidasamy Baskar Shanmugasundaram Sambandam 《Journal of Cluster Science》2021,32(6):1507-1518
Journal of Cluster Science - Nanoparticles synthesized from biopolymers have received attention for their use as biological carriers in the delivery of hydrophobic drugs. Alginate, a marine... 相似文献