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941.
Stephen E Folger Vinay Tannan Zheng Zhang Jameson K Holden Mark Tommerdahl 《BMC neuroscience》2008,9(1):87
Background
Previous reports have demonstrated that short durations of vibrotactile stimuli (less than or equal to 2 sec) effectively and consistently modify both the perceptual response in humans as well as the neurophysiological response in somatosensory cortex. The change in cortical response with adaptation has been well established by a number of studies, and other reports have extended those findings in determining that both GABA- and NMDAR-mediated neurotransmission play a significant role in the dynamic response of somatosensory cortical neurons. In this study, we evaluated the impact that dextromethorphan (DXM), an NMDAR antagonist, had on two distinct vibrotactile adaptation tasks. 相似文献942.
Grobelny Jaroslaw Pradeep Namboodiri Kim Doo-In 《Journal of nanoparticle research》2008,10(1):163-171
In this research, we have studied the doping behaviors of eight transition metal ion dopants on the crystal phase, particle
sizes, XRD patterns, adsorption spectra, anatase fraction, and photoreactivity of TiO2 nanoparticles. The pristine and ion-doped TiO2 nanoparticles of 15.91-25.47 nm were prepared using sol–gel method. Test metal ion concentrations ranged from 0.00002 to
0.2 at.%. The absorption spectra of the TiO2 nanoparticles were characterized using UV-Visible spectrometer. The wavelength of the absorption edge of TiO2 was estimated using the spectra derivative-tangent method. The photoreactivities of pristine and ion-doped TiO2 nanoparticles under UV irradiation were quantified by the decoloring rate of methyl orange. XRD patterns were recorded using
a Rigaku D/MAX-2500 V diffractometer with Cu Kα radiation (50 kV and 250 mA), and particle size and anatase fraction were
calculated. Results reveal that different ion doping exhibited complex effects on the studied characteristics of TiO2 nanoparticles. In general, red shift occurred to ion-doped TiO2 nanoparticles, but still with higher TiO2 photoreactivities when doped with Fe3+ and Ni2+ ions. Among the ions investigated, Ni-doped TiO2 nanoparticles have shown highest photoreactivity at the concentration of 0.002 at.%, about 1.9 times that of the pristine
TiO2. Ion doping was shown to reduce the diameter and influence the fraction of anatase. Data also indicated that the combination
of anatase diameter and ion radius might play an important role in the photoreactivity of TiO2 nanoparticles. This investigation contributes to the understanding of complex ion doping effects on TiO2 nanoparticles, and provides references for enhancing their environmental application. 相似文献
943.
Venkataramanan M Skanth G Bandyopadhyay K Vijayamohanan K Pradeep T 《Journal of colloid and interface science》1999,212(2):553-561
Self-assembled monolayers of diphenyldisufide (DDS), naphthalenedisulfide (NDS), and diphenyldiselenide (DDSe) on polycrystalline silver films have been investigated by surface enhanced Raman spectroscopy (SERS) and X-ray photoelectron spectroscopy (XPS). DDS adsorbs on Ag through a homolytic cleavage of the S-S bond and resultant thiolate at the surface decomposes upon prolonged exposure to air. The geometry of the molecule is such that the benzene ring is almost horizontal to the surface. The Raman spectrum has been assigned in the light of ab-initio molecular orbital calculations. In DDSe, the Se-Se bond is retained upon adsorption and the molecule sticks up. In contrast, NDS is highly reactive on the microscopically rough surface so that a stable monolayer could not be prepared. A temperature dependent Raman study of the DDS monolayer shows the absence of any reorientation at the surface as one would expect from the adsorption geometry. XPS study complements the SERS data and shows the presence of Ag2S on an NDS exposed surface. Copyright 1999 Academic Press. 相似文献
944.
Chikkanti Jaganmohan Vinay Kumar K. P. Sandeep Reddy G. Sandeep Mohanty Jaydeep Kumar Venkateswara Rao B. 《合成通讯》2018,48(2):168-174
A new versatile and efficient strategy for the synthesis of 2,2-bis(dimethylamino)-3-alkyl or benzyl 2,3-dihydroquinazoline-4(1H)-one compounds has been developed by one-pot multicomponent reaction with isatoic anhydride, amines followed by in situ-generated Vilsmeier reagent. The reaction has also been studied with different amines and solvents. 相似文献
945.
Dr. Mari Annadhasan Abhijeet R. Agrawal Surojit Bhunia Vuppu Vinay Pradeep Prof. Sanjio S. Zade Prof. C. Malla Reddy Prof. Rajadurai Chandrasekar 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(33):13956-13962
We present the one-dimensional optical-waveguiding crystal dithieno[3,2-a:2′,3′-c]phenazine with a high aspect ratio, high mechanical flexibility, and selective self-absorbance of the blue part of its fluorescence (FL). While macrocrystals exhibit elasticity, microcrystals deposited at a glass surface behave more like plastic crystals due to significant surface adherence, making them suitable for constructing photonic circuits via micromechanical operation with an atomic-force-microscopy cantilever tip. The flexible crystalline waveguides display optical-path-dependent FL signals at the output termini in both straight and bent configurations, making them appropriate for wavelength-division multiplexing technologies. A reconfigurable 2×2-directional coupler fabricated via micromanipulation by combining two arc-shaped crystals splits the optical signal via evanescent coupling and delivers the signals at two output terminals with different splitting ratios. The presented mechanical micromanipulation technique could also be effectively extended to other flexible crystals. 相似文献
946.
Jay Shukla Yeeshu Kumar Manish K. Dixit Chinthakuntla Mahendar Vinay K. Sharma Abul Kalam Mrigendra Dubey 《化学:亚洲杂志》2020,15(19):3020-3028
A fluorescent metallogel (2.6 % w/v) has been obtained from two non‐fluorescent components viz. phenyl‐succinic acid derived pro‐ligand H2PSL and LiOH (2 equiv.) in DMF. Li+ ion not only plays a crucial role in gelation through aggregation, but also contributed towards enhancement of fluorescence by imposing restriction over excited state intramolecular proton transfer (ESIPT) followed by origin of chelation enhanced fluorescence (CHEF) phenomenon. Further, the participation of CHEF followed by aggregation‐caused quenching (ACQ) and aggregation‐induced emission (AIE) in the gelation process have been well established by fluorescence experiments. Transmission electron microscopy (TEM) analysis disclosed the sequential creation of nanonuclei followed by nanoballs and their alignment towards the generation of fibers of about 3, 31 and 40 nm diameter, respectively. The presence of a long‐range fibrous morphology inside the metallogel was further attested by scanning electron microscopy (SEM). Rheological studies on the metallogel showed its true gel‐phase material nature. Nyquist impedance study shows a resistance value of 7.4 kΩ for the metallogel which upon applying ultrasound increased to 8.5 kΩ, while an elevated temperature of 70 °C caused reduction in the resistance value to 4.8 kΩ. The mechanism behind metallogel formation has been well established by using FTIR, UV‐vis, SEM, TEM, PXRD, 1H NMR, fluorescence and ESI‐MS. 相似文献
947.
Singh PN Mandel SM Sankaranarayanan J Muthukrishnan S Chang M Robinson RM Lahti PM Ault BS Gudmundsdóttir AD 《Journal of the American Chemical Society》2007,129(51):16263-16272
Photolysis of beta-azido propiophenone derivatives, 1, with built-in sensitizer units, leads to selective formation of triplet alkyl nitrenes 2 that were detected directly with laser flash photolysis (lambdamax = 325 nm, tau = 27 ms) and ESR spectroscopy (|D/hc| = 1.64 cm-1, |E/hc| = 0.004 cm-1). Nitrenes 2 were further characterized with argon matrix isolation, isotope labeling, and molecular modeling. The triplet alkyl nitrenes are persistent intermediates that do not abstract H-atoms from the solvent but do decay by dimerizing with another triplet nitrene to form azo products, rather than reacting with an azide precursor. The azo dimer tautomerizes and rearranges to form heterocyclic compound 3. Nitrene 2a, with an n,pi* configuration as the lowest triplet excited state of the its ketone sensitizer moiety, undergoes intramolecular 1,4-H-atom abstraction to form biradical 6, which was identified by argon matrix isolation, isotope labeling, and molecular modeling. beta-Azido-p-methoxy-propiophenone, with a pi,pi* lowest excited state of its triplet sensitizer moiety, does not undergo any secondary photoreactions but selectively yields only triplet alkyl nitrene intermediates that dimerize to form 3b. 相似文献
948.
This paper presents an application for turning and direct modes in a complex composite laminate structure. The propagation and interaction of turning modes and fundamental Lamb modes are investigated in the skin, spar and web sections of a helicopter rotor blade. Finite element models were used to understand the various mode conversions at geometric discontinuities such as web-spar joints. Experimental investigation was carried out with the help of air coupled ultrasonic transducers. The turning and direct modes were confirmed with the help of particle displacements and velocities. Experimental B-Scans were performed on damaged and undamaged samples for qualitative and quantitative assessment of the structure. A strong correlation between the numerical and experimental results was observed and reported. 相似文献
949.
The frictional pressure drop during condensation of HFC-134a and R-404A in a smooth (8.56 mm ID) and micro-fin U-tubes (8.96 mm ID) are experimentally investigated. Different from previous studies, the present experiments are performed for various condensing temperatures. The test runs are done at average saturated condensing temperatures ranging from 35 °C to 60 °C. The mass fluxes are between 90 and 800 kg/m2s. The experimental results indicate that the average frictional pressure drop increases with mass flux but decreases with increasing condensing temperature for both smooth and micro-fin-tubes. The average frictional pressure drops of HFC-134a and R-404A for the micro-fin-tubes were 1-1.7 and 1-2.1 times larger than that in smooth tube respectively. New correlations based on the data gathered during the experimentation for predicting frictional pressure drop are proposed for wide range of operating conditions. 相似文献
950.