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11.
We present a stable regime of asymmetric bound states for spiral pairs in a generic numerical model of a homogeneous excitable medium. In this regime, one spiral tip (slave) rotates around the other (master). Master-slave dynamics occur for both same-chirality and opposite-chirality spiral pairs in a range of parameters and initial conditions. We study the dependency of master-slave characteristics on the medium's excitation threshold and present a phenomenological model that accounts for the qualitative properties of master-slave dynamics. 相似文献
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Peterson RW Anbalagan K Tommos C Wand AJ 《Journal of the American Chemical Society》2004,126(31):9498-9499
A significant fraction of the proteins encoded by the human and other genomes appears to be significantly unfolded in vitro. This will undoubtedly hamper attempts to characterize their structure by classical crystallographic or solution NMR methods. Here we show that encapsulation of a metastable protein within the restricted volume a reverse micelle can be used to force fold the protein and allow its characterization by modern methods of NMR spectroscopy. This may have significant utility in the context of structural proteomics. In addition, variation of the inner volume of the reverse micelle can be used to probe the character of the manifold of unfolded states. 相似文献
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Tissue-simulating phantoms that replicate intrinsic optical properties in a controlled manner are useful for quantitative studies of photon transport in turbid biological media. In such phantoms, polystyrene microspheres are often used to simulate tissue optical scattering. Here, we report that using polystyrene microspheres in fluorescent tissue-simulating phantoms can reduce fluorophore quantum yield via collisional quenching. Fluorescence lifetime spectroscopy was employed to characterize quenching in phantoms consisting of a fluorescein dye and polystyrene microspheres (scattering coefficients
s
100-600cm–1). For this range of tissue-simulating phantoms, analysis using the Stern-Volmer equation revealed that collisional quenching by polystyrene microspheres accounted for a decrease in fluorescence intensity of 6-17% relative to the intrinsic intensity value when no microspheres (quenchers) were present. The intensity decrease from quenching is independent of additional, anticipated losses arising from optical scattering associated with the microspheres. These results suggest that quantitative fluorescence measurements in studies employing such phantoms may be influenced by collisional quenching. 相似文献
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Karthik Arumugam Mallikarjuna Rao Chamallamudi Ravindranath Reddy Gilibili Ramesh Mullangi Subramanian Ganesan Sidhartha S Kar Ranjithkumar Averineni Gopal Shavi Nayanabhirama Udupa 《Biomedical chromatography : BMC》2011,25(3):353-361
A sensitive, specific and accurate HPLC method for the quantification of rivastigmine (RSM) in rat urine was developed and validated. The method involves the simple liquid–liquid extraction of RSM and pyridostigmine as an internal standard (IS) from rat urine with tertiary methyl butyl ether. The chromatographic separation of RSM and IS was achieved with 20 mm ammonium acetate buffer (pH 6.5) and acetonitrile (65:35, v/v) delivered at flow‐rate of 1 mL/min on a Kromasil KR‐100. The method was in linear range from 50 to 5000 ng/mL. The validation was done as per FDA guidelines and the results met the acceptance criteria. The method was successfully applied for the quantification of RSM in rat urine. Besides method validation, we have identified two metabolites of RSM in urine. Both the metabolites were characterized by HPLC‐PDA and LC‐MS/MS and it was found that one metabolite is novel. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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Subramanian Ganesa Sundararajan Karthik Arumugam Baliga Ashok Musmade Prashant Kini Suvarna 《平面色谱法杂志一现代薄层色谱法》2009,22(4):273-276
JPC – Journal of Planar Chromatography – Modern TLC - A sensitive, accurate, precise, and specific high-performance thinlayer chromatographic (HPTLC) method for analysis of bicalutamide... 相似文献
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Raj?Karthik Natarajan?Karikalan Shen-Ming?ChenEmail author Periyasami?Gnanaprakasam Chelladurai?Karuppiah 《Mikrochimica acta》2017,184(2):507-514
The authors describe an electrochemical method for the determination of the anti-cancer drug nilutamide. The method is based on the use of a composite prepared from β-cyclodextrin, gold nanoparticles and graphene oxide (β-CD-AuNP/GO). An alkaline solution of glucose was used as a reducing agent to reduce the gold ions, rather than citric acid and a harmful reducing agent such as hydrazine and sodium borohydride. The structure and surface morphology of the β-CD-AuNP/GO composite was characterized by Raman spectroscopy, transmission electron microscopy and energy-dispersive X-ray spectroscopy. A screen printed carbon electrode was modified with the nanocomposite, and the resulting electrode used as a disposable sensor for the determination of nilutamide by differential pulse voltammetry. Best operated at a working voltage of 0.43 V (vs Ag/AgCl), it exhibits excellent electrocatalytic activity and a detection limit as low as 0.4 nM. The sensor was applied to the determination of nilutamide in (spiked) human serum, as well as in a tablet, where it displays good recovery and accuracy. The sensor is repeatable, reproducible, stable and selective even in the presence of other aromatic nitro compounds. 相似文献
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N. Sankara Subramanian B. Santhi V. Veeraganesh C. Vinoth G. Murugan G. Karthik Subbaraj 《Ionics》2004,10(1-2):56-62
Present work deals with the preparation of TiO2 thin films of different thicknesses by PVD technique using an electron beam and to characterize the films for oxygen gas
detection. The films were characterized using optical transmission measurements, XRD and atomic force microscopy. From the
spectral data, the extinction, absorption coefficient and refractive index of the films are evaluated and reported. The optical
band gap energy varies between 3 and 3.68 eV. The XRD pattern confirms the formation of polycrystalline anatase structure
of Titanium with preferred orientation of (110) plane. The AFM images indicate the presence of coarse and fine grains with
uniform as well as smooth surfaces over the entire range of the analyzed surface. Response characteristics of TiO2 thin films for oxygen gas detection are studied, which indicate a low response time of 120 seconds and high sensitivity of
16 at the operating temperature 450 °C.
Paper presented at the 2nd International Conference on Ionic Devices, Anna University, Chennai, India, Nov. 28–30, 2003. 相似文献
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Boryl (Hetero)aryne Precursors as Versatile Arylation Reagents: Synthesis through CH Activation and Orthogonal Reactivity 下载免费PDF全文
Dr. Emilien Demory Karthik Devaraj Dr. Andreas Orthaber Dr. Paul J. Gates Dr. Lukasz T. Pilarski 《Angewandte Chemie (International ed. in English)》2015,54(40):11765-11769
(Pinacolato)boryl ortho‐silyl(hetero)aryl triflates are presented as a new class of building blocks for arylation. They demonstrate unique versatility by delivering boronate or (hetero)aryne reactivity chemoselectively in a broad range of transformations. This approach enables the unprecedented postfunctionalization of fluoride‐activated (hetero)aryne precursors, for example, as substrates in transition‐metal catalysis, and offers valuable new possibilities for aryl boronate postfunctionalization without the use of specialized protecting groups. 相似文献
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Carbon nanomaterials have been extensively researched in the past few years owing to their interesting properties. The massive research efforts resulted in the emergence of carbon dots, which belong to the carbon nanomaterials family. Carbon dots (C‐dots) have garnered the attention of researchers mainly due to their convenient availability from organic as well as inorganic materials and also due to the novel properties they exhibit. C‐Dots have been said to overcome the era of quantum dots, referring to their levels of toxicity and biocompatibility. In this review, we focus on the discovery of C‐dots, their structure and composition, surface passivation to enhance their optical properties, the various synthetic methods used, their applications in different areas, and future perspectives. Emphasis has been given to greener approaches for the synthesis of C‐dots in order to make them cost effective as well as to improve their biocompatibility. 相似文献