排序方式: 共有66条查询结果,搜索用时 15 毫秒
51.
Vignesh Sekar Se Yong Eh Noum Azma Putra Sivakumar Sivanesan Kok Chun Chin Yi San Wong Dg Hafizah Kassim 《声与振动》2021,55(4):343-352
This paper presents the development and performance of micro-perforated panels (MPP) from natural fiber reinforced composites. The MPP is made of Polylactic Acid (PLA) reinforced with Oil Palm Empty Fruit Bunch Fiber (OPEFBF). The investigation was made by varying the fiber density, air gap, and perforation ratio to observe the effect on the Sound Absorption Coefficient (SAC) through the experiment in an impedance tube. It is found that the peak level of SAC is not affected, but the peak frequency shifts to lower frequency when the fiber density is increased. This phenomenon might be due to the presence of porosity in the inner wall of the holes. Increasing or decreasing the air gap and perforation ratio shifts the peaks of acoustic absorption either way. 相似文献
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What Controls the Magnetic Exchange Interaction in Mixed‐ and Homo‐Valent Mn7 Disc‐Like Clusters? A Theoretical Perspective
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Kuduva R. Vignesh Dr. Stuart K. Langley Prof. Keith S. Murray Prof. Gopalan Rajaraman 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(7):2881-2892
Density functional theory (DFT) studies have been undertaken to compute the magnetic exchange and to probe the origin of the magnetic interactions in two hetero‐ and two homo‐valent heptanuclear manganese disc‐like clusters, of formula [MnII4MnIV3(tea)(teaH2)3(peolH)4] ( 1 ), [MnII4MnIII3F3(tea)(teaH)(teaH2)2(piv)4(Hpiv)(chp)3] ( 2 ), [MnII7(pppd)6(tea)(OH)3] ( 3 ) and [MnII7 (paa)6(OMe)6] ( 4 ) (teaH3=triethanolamine, peolH4=pentaerythritol, Hpiv=pivalic acid, Hchp=6‐chloro‐2‐hydroxypyridine, pppd=1‐phenyl‐3‐(2‐pyridyl) propane‐1,3‐dione; paaH=N‐(2‐pyridinyl)acetoacetamide). DFT calculations yield J values, which reproduce the magnetic susceptibility data very well for all four complexes; these studies are also highlighting the likely ageing/stability problems in two of the complexes. It is found that the spin ground states, S, for complexes 1 – 4 are drastically different, varying from S=29/2 to S=1/2. These values are found to be controlled by the nature of the oxidation state of the metal ions and minor differences present in the structures. Extensive magneto–structural correlations are developed for the seven building unit dimers present in the complexes, with the correlations unlocking the reasons behind the differences in the magnetic properties observed. Independent of the oxidation state of the metal ions, the Mn‐O‐Mn/Mn‐F‐Mn angles are found to be the key parameters, which significantly influence the sign as well as the magnitude of the J values. The magneto–structural correlations developed here, have broad applicability and can be utilised to understand the magnetic properties of other Mn clusters. 相似文献
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Tianhong Pan Biao Huang Weiping Zhang Stephan Gabos Dorothy Yu Huang Vignesh Devendran 《Analytica chimica acta》2013
Although many indices have been developed to quantify chemical toxicity, substantial shortcoming is inherent in most of them, such as observation time dependence, insufficient robustness, and no comparison with the negative control. To assess the extent of exposure of the tested substance, a cytotoxicity assay named AUC50 was developed to describe the time and concentration-dependent cellular responses. By monitoring the dynamic cytotoxicity response profile of living cells via the xCELLigence real-time cell analysis high-throughput (RTCA HT) system, changes in cell number (named cell index, CI) were recorded and analyzed subsequently. A normalized cell index (NCI) is introduced to reduce the influence of inter-experimental variations. The log-phase of cellular growth is considered, which alleviates the cell's spontaneous effect. The area between the control line and the assessed time-dependent cellular response curve (TCRC) of the tested substance was calculated, and the corresponding exponential kill model (concentration–response curve) was developed along with exploiting the concept of AUC50. The validation of the proposed method is demonstrated by exposing HepG2 cell line to seven chemical compounds. Our findings suggested that the proposed AUC-based toxicity assay could be an alternative to the traditional single time-point assay, and it has potential to become routine settings for evaluating the cell-based in vitro assay. Furthermore, the AUC50 combined with RTCA HT assay can be used to achieve a high-throughput screening that conventional cellular assay cannot achieve. 相似文献
56.
Vignesh Athiyarath Prof. Dr. Kana M. Sureshan 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(36):15710-15715
To synthesize a fully organic 1D polymer in a novel twist-stacked topology, we designed a peptide monomer HC≡CCH2-NH-Ile-Leu-N3, which crystallizes with its molecules H-bonded along a six-fold screw axis. These H-bonded columns pack parallelly such that molecules arrange head-to-tail, forming linear non-covalent chains in planes perpendicular to the screw axis. The chains arrange parallelly to form molecular layers which twist-stack along the screw axis. Crystals of this monomer, on heating, undergo single-crystal-to-single-crystal (SCSC) topochemical azide–alkyne cycloaddition (TAAC) polymerization to yield an exclusively 1,4-triazole-linked polymer in a twist-stacked layered topology. This topologically defined polymer shows better mechanical strength and thermal stability than its unordered form, as evidenced by nanoindentation studies and thermogravimetric analysis, respectively. This work illustrates the scope of topochemical polymerizations for synthesizing polymers in pre-decided topologies. 相似文献
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Abstract We report a theoretical calculation of the band structure and superconductivity of niobium carbide in the NaCl structure under pressure. The effect of pressure on the band structure is obtained by means of the self-consistent linear muffin-tin orbital method. The parameters necessary to calculate the superconducting transition temperature (Tc) are taken from our band structure results. The dependence of total energy on volume is calculated and is in good agreement with other earlier works. The calculated value of the cell parameter is in agreement with the experimental value (8.45 a.u). McMillan formula is used to calculate the value of Tc The calculated values of Tc are compared with the available experimental data. 相似文献
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G. Raje B. J. Kalaiselvi D. Shanmukaraj R. Sridarane B. Palanivel Ramaswamy Murugan 《Ionics》2004,10(3-4):263-267
The transport phenomena in alkali-metal super ionic conductors based on Na3PO4 structure are of particular interest due to their potential technological application. Differential thermal analysis (DTA),
differential scanning calorimetry (DSC), Raman spectroscopy and temperature dependent electrical conductivity measurements
were carried out to probe the nature of the phase transformation involved in anhydrous Na3PO4. The changes in spectral profile of the v3 mode and the line width of v1 mode of PO
4
3−
observed in the temperature interval from 331 to 345 °C revealed the high degree of disorder nature during the α-γNa3PO4 phase transformation.
Paper presented at the 2nd Internation Conference on Ionic Devices, Anna University, Chennai, India, Nov. 28–30, 2003. 相似文献
59.
Improved efficiencies of hybrid organic light‐emitting diodes using efficient electron injection layer
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Jayaraman Jayabharathi Pavadai Nethaji Venugopal Thanikachalam Palanivel Jeeva Ramaiyan Ramya 《Journal of Physical Organic Chemistry》2018,31(6)
Hybrid organic‐inorganic light‐emitting diodes were developed with pristine ZnO (2.0 wt%) and Cu‐doped ZnO (2.0 wt%) as electron injection layer and iridium(III)‐bis‐2‐(4‐fluorophenyl)‐1‐(naphthalen‐1‐yl)‐1H‐phenanthro[9,10‐d]imidazole (acetylacetonate) [Ir(fpnpi)2 (acac)] as green emissive layer (521 nm). The pristine ZnO and Cu‐doped ZnO are deposited at indium tin oxide cathode and emissive layer interface. The electroluminescent performances increased by electron injection layer–Cu‐doped ZnO compared with ZnO‐based device because Cu‐doped ZnO injects electron efficiently result in balanced h+ ? e? recombination in emissive layer than ZnO‐based device. The Cu‐doped ZnO (2.0 %) device shows luminance (L) of 10 982 cd/m2 at 23.0 V (ZnO, 1450 cd/m2 at 23.0 V). 相似文献
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Dawei Jiang Vignesh Murugadoss Ying Wang Jing Lin Tao Ding Zicheng Wang 《高分子科学杂志,C辑:聚合物评论》2019,59(2):280-337
Intrinsically conducting polymers (ICP) and conductive fillers incorporated conductive polymer-based composites (CPC) greatly facilitate the research in electromagnetic interference (EMI) shielding because they not only provide excellent EMI shielding but also have advantages of electromagnetic wave absorption rather than reflection. In this review, the latest developments in ICP and CPC based EMI shielding materials are highlighted. In particular, existing methods for adjusting the morphological structure, electric and magnetic properties of EMI shielding materials are discussed along with the future opportunities and challenges in developing ICP and CPC for EMI shielding applications. 相似文献