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391.
A. Asokan Pravat K. Manual Babu Varghese P. T. Manoharan 《Journal of Chemical Sciences》1995,107(4):281-295
A binuclear copper(II) complex [Cu2L(OH)](C1O4)2·2H2O has been synthesized and characterized by X-ray crystallography and1H-NMR studies. The crystal structure shows that the bridging angles between Cu(l)-O(l)-Cu(2) and Cu(l)-O(2)-Cu(2) are 98.9(2)°
and 102.2(2)° respectively. The Cu(l)-Cu(2) distance is 3.0097(12)?. This indicates that the interaction between the two copper
atoms is antiferromagnetic in nature. The geometry around Cu(l) is distorted square-pyramid with one water molecule occupying
the axial fifth position, whereas, the geometry around Cu(2) is distorted square-planar with weak interactions of one of the
perchlorate anion. There are eight molecules present in the unit cell. There is an interdimer interaction between the dimers.
The temperature-dependent1H-NMR chemical shift studies have been performed on six different protons of this complex which reveals that the exchange
coupling constant (− 2J) is same for all protons (208 ± 1 cm−1). However, the hyperfine coupling constant (A′) was found to be different in magnitude as well as in sign. We also report solvent dependent NMR properties. 相似文献
392.
Diffraction methods present the most direct approach to studying the electron distribution, and hence various theories of the chemical bond, in transition metal complexes. Results that have emerged from X-ray diffraction, the combination of X-ray and neutron diffraction, and finally, polarised neutron scattering by paramagnetic crystals are summarised. 相似文献
393.
Spectral estimators in elastography 总被引:1,自引:0,他引:1
Like velocity, strain induces a time delay and a time scaling to the received signal. Elastography typically uses time delay techniques to indirectly (i.e. via the displacement estimate) measure tissue strain induced by an applied compression, and considers time scaling as a source of distortion. More recently, we have shown that the time scaling factor can also be spectrally estimated and used as a direct measure of strain. Strain causes a Doppler-like frequency shift and a change in bandwidth of the bandpass power spectrum of the echo signal. Two frequency shift strain estimators are described that have been proven to be more robust but less precise when compared to time delay estimators, both in simulations and experiments. The increased robustness is due to the insensitivity of the spectral techniques to phase decorrelation noise. In this paper we discuss and compare the theoretical and experimental findings obtained with traditional time delay estimators and with the newly proposed spectral methods. 相似文献
394.
Jacob Thottathil Varghese Sajan Thomas Joselin Herbert Chacko Preno Koshy Arjun Venugopal 《声与振动》2022,56(3):255-274
The arrangement of natural and physical features on the earth’s surface are a few among the countless items that govern the airborne acoustic transmission at boundary layers. In particular, if the acoustic waves are attributes of live concerts at open-air theatres, without losing the sheen and quality, the audience should certainly receive the unbroken depth of the performance. Hence, at all times, it is advisable to analyse the auditory receptiveness, particularly in all intended recreational spaces. The current pandemic circumstances and the mandated COVID-19 prevention protocols encourage gatherings in naturally ventilated outdoor regions than confined indoors. This work predicts and quantifies the acoustic experience at the naturally carved amphitheatre at SAINTGITS, an autonomous institution at the down South-West of the Indian Subcontinent. The entire recreational space at SAINTGITS AMPHI was separately modelled as a Base case and Advanced case, and were analysed using the acoustic modelling module of EASE Focus, a renowned simulation freeware, which is in strict adherence with the International standards. The variation in loudness received at the nearest and farthest ends of the amphitheatre was between 67 to 80 dB. Though the Zero frequency SPL (Z-weighting) exhibited the loudness in the range of 81 to 85 dB and could maintain a safer auditory level for any human ear, it was confined to a hemispherical region near the sound source. A vertical beam angle of −4.0° was found to be effective throughout. The procedures and analyses will certainly help the future organizers and stakeholders to effectively plan the resources to reap rich acoustic experience at terrain-centric locales. The surface topography and contours were plotted with another set of freeware, the CADMAPPER and the QUIKGRID, to compare terrain gradient with the known data. Furthermore, this interdisciplinary research exhibits the extensive simulation capability of both EASE Focus and QUIKGRID and demonstrates the modelling versatility and deliverable potential of these freeware to benefit the budding architects and researchers. 相似文献
395.
Growth of single crystals of the title compound Sr(C4H4O5).3H2O is achieved using the gel diffusion technique. Multifaceted single crystals of size up to 4x3x3 mm3 are obtained. X‐Ray Diffraction (XRD) pattern of the grown crystal and the Fourier Transform Infra‐Red (FTIR) spectrum in the range 400‐4000 cm‐1 are recorded. The vibrational bands corresponding to different functional groups are assigned. Thermal behavior of the material is investigated using Thermo Gravimetry (TG) and Differential Thermal Analysis (DTA). Thermal studies are indicative of a five‐stage decomposition scheme. © 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim 相似文献
396.
Panicker CY Varghese HT Philip D Nogueira HI Castkova K 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2007,67(5):1313-1320
Methyl(2-methyl-4,6-dinitrophenylsulfanyl)ethanoate was prepared by nucleophilic substitution. FT-IR and FT-Raman spectra of methyl(2-methyl-4,6-dinitrophenylsulfanyl)ethanoate were recorded and analyzed. Surface-enhanced Raman scattering (SERS) spectrum was recorded on a silver colloid. The vibrationl wavenumbers were computed by density functional theoretical (DFT) computations at the B3LYP/6-31G* level and they were found to be in good agreement with the experimental values. The molecule is adsorbed on the silver surface with the benzene ring in a 'tilted orientation'. 相似文献
397.
Varghese HT Panicker CY Philip D Sreevalsan K Anithakumary V 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2007,68(3):817-822
The IR and Raman spectra of disodium terephthalate were recorded and analysed. Surface enhanced Raman scattering (SERS) spectrum was recorded in silver colloid. The vibrational wavenumber of the compound have been computed using the Hartree-Fock/6-31G* basis and compared with the experimental values. SERS studies suggest a flat orientation of the molecule at the metal surface. 相似文献
398.
Thomas Varghese 《School science and mathematics》2011,111(8):409-415
The National Council of Teachers of Mathematics calls for an increased emphasis on proof and reasoning in school mathematics curricula. Given such an emphasis, mathematics teachers must be prepared to structure curricular experiences so that students develop an appreciation for both the value of proof and for those strategies that will assist them in developing proving skills. Such an outcome is more likely when the teacher feels secure in his/her own understanding of the concept of “mathematical proof” and understands the ways in which students progress as they take on increasingly more complex mathematical justifications. In this article, a model of mathematical proof, based on Balacheff's Taxonomy of Mathematical Proof, outlining the levels through which students might progress as they develop proving skills is discussed. Specifically, examples of the various ways in which students operating at different levels of skill sophistication could approach three different mathematical proof tasks are presented. By considering proofs under this model, teachers are apt to gain a better understanding of each student's entry skill level and so effectively guide him/her toward successively more sophisticated skill development. 相似文献
399.
JPC – Journal of Planar Chromatography – Modern TLC - This paper describes a validated high-performance thin-layer chromatography (HPTLC) method for the simultaneous determination of... 相似文献
400.
Varghese SJ Johny SK Paul D Ravi TK 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,79(2):384-387
The in vitro protein binding of retinoic acid isomers (isotretinoin and tretinoin) and the antihypertensive drugs (amlodipine and telmisartan) was studied by equilibrium dialysis method. In this study, free fraction of drugs and the % of binding of drugs in the mixture to bovine serum albumin (BSA) were calculated. The influence of retinoic acid isomers on the % of protein binding of telmisartan and amlodipine at physiological pH (7.4) and temperature (37±0.5°C) was also evaluated. The in vitro displacement interaction study of drugs telmisartan and amlodipine on retinoic acid isomers and also interaction of retinoic acid isomers on telmisartan and amlodipine were carried out. 相似文献