排序方式: 共有66条查询结果,搜索用时 15 毫秒
31.
Slow Magnetic Relaxation and Single‐Molecule Toroidal Behaviour in a Family of Heptanuclear {CrIIILnIII6} (Ln=Tb,Ho, Er) Complexes 下载免费PDF全文
Dr. Kuduva R. Vignesh Dr. Stuart K. Langley Abinash Swain Dr. Boujemaa Moubaraki Dr. Marko Damjanović Prof. Wolfgang Wernsdorfer Prof. Gopalan Rajaraman Prof. Keith S. Murray 《Angewandte Chemie (International ed. in English)》2018,57(3):779-784
The synthesis, magnetic properties, and theoretical studies of three heterometallic {CrIIILnIII6} (Ln=Tb, Ho, Er) complexes, each containing a metal topology consisting of two Ln3 triangles connected via a CrIII linker, are reported. The {CrTb6} and {CrEr6} analogues display slow relaxation of magnetization in a 3000 Oe static magnetic field. Single‐crystal measurements reveal opening up of the hysteresis loop for {CrTb6} and {CrHo6} molecules at low temperatures. Ab initio calculations predict toroidal magnetic moments in the two Ln3 triangles, which are found to couple, stabilizing a con‐rotating ferrotoroidal ground state in Tb and Ho examples and extend the possibility of observing toroidal behaviour in non DyIII complexes for the first time. 相似文献
32.
Large Hexadecametallic {MnIII–LnIII} Wheels: Synthesis,Structural, Magnetic,and Theoretical Characterization 下载免费PDF全文
Kuduva R. Vignesh Dr. Stuart K. Langley Dr. Boujemaa Moubaraki Prof. Keith S. Murray Prof. Gopalan Rajaraman 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(46):16364-16369
The synthesis, gas sorption studies, magnetic properties, and theoretical studies of new molecular wheels of core type {MnIII8LnIII8} (Ln=Dy, Ho, Er, Y and Yb), using the ligand mdeaH2, in the presence of ortho‐toluic or benzoic acid are reported. From the seven wheels studied the {Mn8Dy8} and {Mn8Y8} analogues exhibit SMM behavior as determined from ac susceptibility experiments in a zero static magnetic field. From DFT calculations a S=16 ground state was determined for the {Mn8Y8} complex due to weak ferromagnetic MnIII–MnIII interactions. Ab initio CASSCF+RASSI‐SO calculations on the {Mn8Dy8} wheel estimated the MnIII–DyIII exchange interaction as ?0.1 cm?1. This weak exchange along with unfavorable single‐ion anisotropy of DyIII/MnIII ions, however, led to the observation of SMM behavior with fast magnetic relaxation. The orientation of the g‐anisotropy of the DyIII ions is found to be perpendicular to the plane of the wheel and this suggests the possibility of toroidal magnetic moments in the cluster. The {Mn8Ln8} clusters reported here are the largest heterometallic MnIIILnIII wheels and the largest {3d–4f} wheels to exhibit SMM behavior reported to date. 相似文献
33.
Abstract We report here a calculation of the band structure and superconductivity of Arsenic in the simple cubic phase under pressure. The effect of pressure on the band structure is obtained using Andersen's linear muffin-tin orbital method under atomic sphere approximation. McMillan's formula is used to calculate the superconducting transition temperature (Tc). The theoretically calculated valve of Tc in sc phase at 26.6 GPa is 3.62 K. Further increase in pressure decreases the Tc values. 相似文献
34.
Abstract Here we report a theoretical calculation of the band structure and superconductivity of Se in the bcc phase. The energy band structure and the effect of pressure on the band structure is obtained by means of the Linear Muffin-Tin Orbital method within the atomic sphere approximation. The superconducting transition temperature (Tc) is calculated using McMillan's formula and we predict the value of Tc at 115.3 Gpa as 2.3 K. Further increase in presssure decreases the Tc values. The normal state electrical resistivity at 115.3 Gpa is 1.43 fl cm, with further increase in pressure the resistivity decreases, which is a typical behaviour of number of elemental metals under pressure. 相似文献
35.
Badral Gansukh Qiuyue Zhang Chantsalnyam Bariashir Arumugam Vignesh Yanping Ma Tongling Liang Wen-Hua Sun 《Molecules (Basel, Switzerland)》2020,25(23)
By dealing CrCl3∙3THF with the corresponding ligands (L1–L5), an array of fluoro-substituted chromium (III) chlorides (Cr1–Cr5) bearing 2-[1-(2,4-dibenzhydryl-6-fluoro- phenylimino)ethyl]-6-[1-(arylimino)ethyl]pyridine (aryl = 2,6-Me2Ph Cr1, 2,6-Et2Ph Cr2, 2,6-iPr2Ph Cr3, 2,4,6-Me3Ph Cr4, 2,6-Et2-4-MePh Cr5) was synthesized in good yield and validated via Fourier Transform Infrared (FT-IR) spectroscopy and elemental analysis. Besides the routine characterizations, the single-crystal X-ray diffraction study revealed the solid-state structures of complexes Cr2 and Cr4 as the distorted-octahedral geometry around the chromium center. Activated by either methylaluminoxane (MAO) or modified methylaluminoxane (MMAO), all the chromium catalysts exhibited high activities toward ethylene polymerization with the MMAO-promoted polymerizations far more productive than with MAO (20.14 × 106 g (PE) mol−1 (Cr) h−1 vs. 10.03 × 106 g (PE) mol−1 (Cr) h−1). In both cases, the resultant polyethylenes were found as highly linear polyethylene waxes with low molecular weights around 1–2 kg mol−1 and narrow molecular weight distribution (MWD range: 1.68–2.25). In general, both the catalytic performance of the ortho-fluorinated chromium complexes and polymer properties have been the subject of a detailed investigation and proved to be highly dependent on the polymerization reaction parameters (including cocatalyst type and amount, reaction temperature, ethylene pressure and run time). 相似文献
36.
Sankaranarayanan Kavitha Ramachandran Raja Prabhu Kumar Raghavan Muralitharen Sinthu S. Mansoor Usman M. Sriram Kumar V. Madan Kumar S. Vignesh V. Malini K.M. Cherian S. Madhivanan Sankaranarayanan Karthik Natarajan Arutselvan Sundararajan Raji 《Journal of Electrostatics》2011,69(4):267-274
Clinically chemo-resistant types of cancers do not respond well to conventional therapies. To treat and enhance the efficacy of drug delivery for these cancers, we have developed an in vitro model of a combination therapy using adult human mesenchymal stem cells, electrical pulses and chemo drug. Adult Mesenchymal stem cells were used because they are similar to cancer stem cells which cause the tumor to be chemo- and radiation resistant. These cells, derived from human adult bone marrow were subjected to low voltage, long duration (200 V/cm, 40 ms and 450 V/cm, 25 ms) and high voltage, short duration (1200 V/cm, 100 μs) pulses. The effect of these voltages on the viability and proliferation ability of these cells in the presence and absence of Bleomycin (chemodrug used for treating various cancers, FDA approved in US and other respective medical agencies in other countries,) indicate the potential of transfer of this technique to clinical practice for effective electro-targeted stem cell therapy. 相似文献
37.
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
38.
Vignesh Kasinath Dr. Yinan Fu Prof. Kim A. Sharp Prof. A. Joshua Wand 《Angewandte Chemie (International ed. in English)》2015,54(1):102-107
Aromatic amino acid side chains have a rich role within proteins and are often central to their structure and function. Suitable isotopic‐labelling strategies enable studies of sub‐nanosecond aromatic‐ring dynamics using solution NMR relaxation methods. Surprisingly, it was found that the three aromatic side chains in human ubiquitin show a sharp thermal dynamical transition at approximately 312 K. Hydrostatic pressure has little effect on the low‐temperature behavior, but somewhat decreases the amplitude of motion in the high‐temperature regime. Therefore, below the transition temperature, ring motion is largely librational. Above this temperature, a complete ring‐rotation process that is fully consistent with a continuous diffusion not requiring the transient creation of a large activated free volume occurs. Molecular dynamics simulations qualitatively corroborate this view and reinforce the notion that the dynamical character of the protein interior has much more liquid‐alkane‐like properties than previously appreciated. 相似文献
39.
A Study on Nucleate Boiling Heat Transfer Characteristics of Acetone on Smooth and Indented Surfaces
This article presents the nucleate boiling heat transfer characteristics of acetone at one bar on smooth and enhanced circular stainless steel surfaces (SS 316) of 20 mm diameter for heat flux between 1 and 4 W cm? 2, which mimic the operating condition of a typical immersion electronic cooling system. The experimental heat transfer coefficient from the smooth surface is validated against Borishanski correlation [1] within acceptable limits of ± 5%. The steel smooth surface is enhanced by providing 100 equally spaced indents of 0.5 mm diameter and 0.05 mm depth. The experimental results indicate that the enhanced surface shows a good shift in the boiling curve and thus, enhancing the nucleate boiling heat transfer at a lesser wall super heat when compared to the smooth surface by around 35% for tested condition. The effect of subcooling on nucleate boiling in enhanced surface reveal that the heat transfer coefficient degrade by 40 to 55% for a sub cooling of 5 to 10 K. The influence of material is studied by a similar enhanced surface made of brass and compared for the same working condition. The brass enhanced surface showed an improved of around 50% against the steel-enhanced surface. Also, the influence of fluid is studied by comparing acetone and n-pentane, which showed that the latter an enhancement in heat transfer coefficient of 50% over the former. 相似文献
40.