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61.
Reactions of PhAsCl2 with BrMg(CH2)nMgBr (n = 4 or 5) in THF gave phenylarsacycloalkanes as colourless oily liquids which could be distilled under vacuum. Treatment of PhAs(CH2)nwith MCl2(RCN)2 (M = Pd or Pt; R = Phor Me) afforded mononuclear complexes, [MCl2{PhAs(CH2)n}2]. Reactions with [Pt2Cl2(μ‐Cl)2(PEt3)2] gave mixed‐ligand complexes, [PtCl2(PEt3){PhAs(CH2)n]. The palladium complexes adopt a trans geometry whereas the platinum complexes exist in a cis configuration. The crystal and molecular structure of [PdCl2(PhAsCH2CH2CH2CH2CH2)2] was determined by X‐ray diffraction methods. The molecule consists of a square‐planar palladium atom with trans chlorides and trans arsa ligands. The six‐membered ‘AsC5′ ring adopts a chair conformation. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
62.
Panicker Devyani Ramachandran Mahesh Doddadasarahalli Muniyappa Sreelekha Kanapadinchareveetil Suresh Narayanan Nair Karapparambu Gopalan Ajithkumar Sujith Samraj Anoopraj Rajappan Anju Varghese Deepa Chundayil Kalarickal Reghu Ravindran Srikanta Ghosh Sanis Juliet 《Molecules (Basel, Switzerland)》2021,26(16)
Prostaglandins are a group of important cell-signaling molecules involved in the regulation of ovarian maturation, oocyte development, egg laying and associated behaviors in invertebrates. However, the presence of prostaglandin E2 (PGE2), the key enzymes for PGE2 biosynthesis and its interference by drugs were not investigated previously in the ovary of ticks. The present study was undertaken to assess the modulation of the PGE2-mediated pathway in the eclosion blocking effect of flumethrin and terpenoid subfraction isolated from Artemisia nilagirica in Rhipicephalus annulatus ticks. The acaricidal activities and chemical profiling of the terpenoid subfraction were performed. The localization of the cyclooxygenase1 (COX1) and prostaglandin E synthase (PGES) enzymes and the quantification of PGE2 in the ovaries of the ticks treated with methanol (control), flumethrin and terpenoid subfraction were also undertaken. In addition, the vitellogenin concentration in hemolymph was also assayed. Both flumethrin and the terpenoid subfraction of A. nilagirica elicited a concentration-dependent inhibition of fecundity and blocking of hatching of the eggs. The COX1 could not be detected in the ovaries of treated and control ticks, while there was no significant difference observed in the concentration of vitellogenin (Vg) in them. The presence of PGES in the oocytes of control ticks was confirmed while the immunoreactivities against PGES were absent in the vitellogenic oocytes of ticks treated with flumethrin and terpenoid subfraction. The levels of PGE2 were below the detection limit in the ovaries of the flumethrin-treated ticks, while it was significantly lower in the ovaries of the terpenoid subfraction-treated ticks. Hence, the prostaglandin E synthase and PGE2 were identified as very important mediators for the signaling pathway for ovarian maturation and oviposition in ticks. In addition, the key enzyme for prostaglandin biosynthesis, PGES and the receptors for PGE2 can be exploited as potential drug targets for tick control. The detection of PGES by immunohistochemistry and quantification of PGE2 by LC-MSMS can be employed as valuable tools for screening newer compounds for their eclosion blocking acaricidal effects. 相似文献
63.
Hairong Shi Tomy Varghese Carol C. Mitchell Matthew McCormick Robert J. Dempsey Mark A. Kliewer 《Ultrasonics》2009,49(8):779-785
We have previously reported on the equivalent scatterer size, attenuation coefficient, and axial strain properties of atherosclerotic plaque ex vivo. Since plaque structure and composition may be damaged during a carotid endarterectomy procedure, characterization of in vivo properties of atherosclerotic plaque is essential. The relatively shallow depth of the carotid artery and plaque enables non-invasive evaluation of carotid plaque utilizing high frequency linear-array transducers. We investigate the ability of the attenuation coefficient and equivalent scatterer size parameters to differentiate between calcified, and lipidic plaque tissue. Softer plaques especially lipid rich and those with a thin fibrous cap are more prone to rupture and can be classified as unstable or vulnerable plaque. Preliminary results were obtained from 10 human patients whose carotid artery was scanned in vivo to evaluate atherosclerotic plaque prior to a carotid endarterectomy procedure. Our results indicate that the equivalent scatterer size obtained using Faran’s scattering theory for calcified regions are in the 120–180 μm range while softer regions have larger equivalent scatterer size distribution in the 280–470 μm range. The attenuation coefficient for calcified regions as expected is significantly higher than that for softer regions. In the frequency bandwidth ranging from 2.5 to 7.5 MHz, the attenuation coefficient for calcified regions lies between 1.4 and 2.5 dB/cm/MHz, while that for softer regions lies between 0.3 and 1.3 dB/cm/MHz. 相似文献
64.
Shear stresses are always present during quasi-static strain imaging, since tissue slippage occurs along the lateral and elevational directions during an axial deformation. Shear stress components along the axial deformation axes add to the axial deformation while perpendicular components introduce both lateral and elevational rigid motion and deformation artifacts into the estimated axial and lateral strain tensor images. A clear understanding of these artifacts introduced into the normal and shear strain tensor images with shear deformations is essential. In addition, signal processing techniques for improved depiction of the strain distribution is required. In this paper, we evaluate the impact of artifacts introduced due to lateral shear deformations on the normal strain tensors estimated by varying the lateral shear angle during an axial deformation. Shear strains are quantified using the lateral shear angle during the applied deformation. Simulation and experimental validation using uniformly elastic and single inclusion phantoms were performed. Variations in the elastographic signal-to-noise and contrast-to-noise ratios for axial deformations ranging from 0% to 5%, and for lateral deformations ranging from 0 to 5° were evaluated. Our results demonstrate that the first and second principal component strain images provide higher signal-to-noise ratios of 20 dB with simulations and 10 dB under experimental conditions and contrast-to-noise ratio levels that are at least 20 dB higher when compared to the axial and lateral strain tensor images, when only lateral shear deformations are applied. For small axial deformations, the lateral shear deformations significantly reduces strain image quality, however the first principal component provides about a 1–2 dB improvement over the axial strain tensor image. Lateral shear deformations also significantly increase the noise level in the axial and lateral strain tensor images with larger axial deformations. Improved elastographic signal and contrast-to-noise ratios in the first principal component strain image are always obtained for both simulation and experimental data when compared to the corresponding axial strain tensor images in the presence of both axial and lateral shear deformations. 相似文献
65.
66.
C. Yohannan Panicker Hema Tresa Varghese Asha Raj K. Raju Tugba Ertan-Bolelli Ilkay Yildiz Ozlem Temiz-Arpaci Carlos M. Granadeiro Helena I.S. Nogueira 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2009,74(1):132-139
The FT-IR and FT-Raman spectra of 2-phenoxymethylbenzothiazole were recorded and analyzed. The surface enhanced Raman scattering (SERS) spectrum was recorded in a silver colloid. The vibrational wavenumbers of the compound have been computed using the Hartree–Fock/6-31G* basis and compared with the experimental values. The appearance of the Ag–O stretching mode at 237 cm−1 in the SERS spectrum along with theoretically calculated atomic charge density, leads us to suggest that the molecule is adsorbed through the oxygen atom with the molecular plane tilted on the colloidal silver surface. The direction of charge transfer contribution to SERS has been discussed from the frontier orbital theory. 相似文献
67.
Online grocers accept delivery bookings and have to deliver groceries to consumers’ residences. Grocery stores operate on very thin margins. Therefore, a critical question that an online grocery store needs to address is the cost of home delivery operations. In this paper, we develop a Markov decision process-based pricing model that recognizes the need to balance utilization of delivery capacity by the grocer and the need to have the goods delivered at the most convenient time for the customer. The model dynamically adjusts delivery prices as customers arrive and make choices. The optimal prices have the following properties. First, the optimal prices are such that the online grocer gains the same expected payoff in the remaining booking horizon, regardless of the delivery option independently chosen by a consumer. Second, with unit order sizes, delivery prices can increase due to dynamic substitution effects as there is less time left in the booking horizon. 相似文献
68.
Ajayaghosh A Vijayakumar C Praveen VK Babu SS Varghese R 《Journal of the American Chemical Society》2006,128(22):7174-7175
Control over supramolecular assemblies of donor and acceptor arrays in nanoscale dimension that facilitate efficient energy transfer resulting in tunable emission is an outstanding challenge. In pursuit of this goal, we have designed a supramolecular donor-acceptor organogel with tunable emission from green to red through controlled energy transfer by simply varying the acceptor concentration. Temperature-dependent UV/vis absorption, XRD, and AFM studies of the coassembly of 1 (donor) and 2 (acceptor) revealed the intercalation of 2 within the self-assembly of 1. Upon excitation of the decane gels of 1 with 0-2 mol % of 2, quenching of the emission of the former at 509 nm with the formation of the monomer emission of the latter at 555 nm is observed. Upon further addition of 2 (2-20 mol %), the emission was continuously red-shifted to 610 nm, which corresponds to the aggregate emission of 2. Consequently, a 98% quenching of the donor emission was observed at 509 nm. Fluorescence microscopic studies provided visual evidence for the color tuning of the FRET emission. Thus efficient trapping of excitons by "isolated" or "aggregated" acceptors through a subtle control of the self-assembly and the photophysical properties of the donor-acceptor building blocks allowed a continuous shifting of the emission color anywhere between green and red (lambdamax, 509-610 nm) in a supramolecular light harvesting system. 相似文献
69.
Janarthanan Gopalakrishnan Babu Varghese Adinarayana Doddi M. N. Sudheendra Rao 《应用有机金属化学》2006,20(12):880-885
The phosphetidine 2,4‐Di‐tert‐butyl‐3‐chloro‐1λ6‐thia‐2,4‐diaza‐3‐phosphetidine‐1,1‐dioxide, O2S (tBuN)2PCl, reacts with tetrasulfur tetranitride, S4N4, in benzene under reflux to afford the novel 4,6‐spirocycle in moderate yield. The deep‐blue crystals of the spirocycle are airstable and high melting in nature. The spiro phosphorus atom subtends a four‐membered PVSVIN2 ring which is saturated, and a six‐membered PVS N3 ring which is unsaturated. The single‐crystal X‐ray structure of this first example of the spirocycle reveals a planar PSN2 ring and a puckered PS2N3 ring and the molecule is symmetric in nature. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
70.
We report on the quantitative influence of speckles in laser Doppler perfusion imaging. The influence of speckles on the signal amplitude and on the Doppler spectrum is demonstrated experimentally for particle suspensions with different scattering levels and various beam widths. It is shown that the type of tissue affects the instrumental response through the effect of lateral light diffusion on the number of speckles involved in the detection process. These effects are largest for narrow beams. 相似文献