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排序方式: 共有119条查询结果,搜索用时 343 毫秒
111.
Iwai H Fang-Yen C Popescu G Wax A Badizadegan K Dasari RR Feld MS 《Optics letters》2004,29(20):2399-2401
We describe a quantitative phase-imaging interferometer in which phase shifting and noise cancellation are performed by an active feedback loop using a reference laser. Depth gating via low-coherence light allows phase measurement from weakly reflecting biological samples. We demonstrate phase images from a test structure and living cells. 相似文献
112.
Fang-Yen C Oh S Park Y Choi W Song S Seung HS Dasari RR Feld MS 《Optics letters》2007,32(11):1572-1574
We describe a heterodyne Mach-Zehnder interferometric microscope capable of quantitative phase imaging of biological samples with subnanometer sensitivity and frame rates up to 10 kHz. We use the microscope to image cultured neurons and measure nanometer-scale voltage-dependent motions in cells expressing the membrane motor protein prestin. 相似文献
113.
Choi Y Yang TD Fang-Yen C Kang P Lee KJ Dasari RR Feld MS Choi W 《Physical review letters》2011,107(2):023902
We report that disordered media made of randomly distributed nanoparticles can be used to overcome the diffraction limit of a conventional imaging system. By developing a method to extract the original image information from the multiple scattering induced by the turbid media, we dramatically increase a numerical aperture of the imaging system. As a result, the resolution is enhanced by more than 5 times over the diffraction limit, and the field of view is extended over the physical area of the camera. Our technique lays the foundation to use a turbid medium as a far-field superlens. 相似文献
114.
A Stereoselective Aldol Approach for the Total Syntheses of Two 6‐Alkylated 2H‐Pyran‐2‐ones 下载免费PDF全文
Singanaboina Rajaram Dasari Ramesh Udugu Ramulu Peddikotla Prabhakar Yenamandra Venkateswarlu 《Helvetica chimica acta》2014,97(1):112-121
A simple and highly efficient stereoselective total synthesis of the 6‐alkylated pyranones (6R)‐6‐[(1E,4R,6R)‐4,6‐dihydroxy‐10‐phenyldec‐1‐en‐1‐yl]‐5,6‐dihydro‐2H‐pyran‐2‐one ( 1 ) and (6S)‐5,6‐dihydro‐6‐[(2R)‐2‐hydroxy‐6‐phenylhexyl]‐2H‐pyran‐2‐one ( 2 ) was developed using Crimmins' aldol reaction, SmI2 reduction, Grubbs‐II‐catalyzed olefin cross‐metathesis, and Still's modified Horner? Wadsworth? Emmons reaction. 相似文献
115.
R. Acharya K. B. Dasari D. Chandra Shekhar T. P. Chaturvedi P. K. Pujari 《Journal of Radioanalytical and Nuclear Chemistry》2014,302(3):1333-1337
A digital gamma-ray spectrometer with loss-free counting system was used for real time correction for dead time (DT) due to pulse processing in the electronics. This spectrometer was used for radioactive assay of samples having constant as well as varying DT conditions. The system was tested by measuring activity of short and medium lived nuclides namely 28Al, 52V and 128I in the DT ranges of 80–2 %. Using this spectrometer and neutron activation analysis (NAA), concentrations of Al, V, Ti, Ca, Dy and Mn were determined in some samples and reference materials. 相似文献
116.
Evaluation of soil to tea plant elemental correlation using instrumental neutron activation analysis
Rupali A. Lagad K. B. Dasari D. Alamelu R. Acharya Suresh K. Aggarwal 《Journal of Radioanalytical and Nuclear Chemistry》2014,302(3):1507-1512
Instrumental neutron activation analysis using relative and k 0-based internal monostandard methods were employed for determination of concentrations of 12 elements in soil and tea plants collected from three different tea producing regions in India namely Assam, Darjeeling and Kangra. A total of 17 tea leaf samples along with corresponding soil samples were analyzed for elemental content. The obtained concentration data was used for the soil–plant elemental correlation studies. Positive correlation was observed between elemental concentrations of tea plants and the associated soil with Pearson correlation coefficient values in the range 0.6–0.9 for ten elements. Variations in transfer factor values were also observed according to the geo-chemical variation. 相似文献
117.
Calculations are presented on six-π-electron N-B-N- and B-N-B-substituted benzene rings, [C(3)BN(2)H(6)](+) and [C(3)NB(2)H(6)](-), and their isomers. These compounds display a wide range of thermodynamic stability in those molecules, with N-B-N connectivity favored strongly in the cation, B-N-B in the anion. That stability order is easily understood using the charge distribution in a benzene polarized by heteroatom substitutions or the underlying allyl anion and cation. Deprotonation at N in [C(3)BN(2)H(6)](+) leads to a set of BN-substituted pyridines. The calculations predicted three B-N-substituted pyridines clearly more stable thermodynamically than those synthesized so far. The order of stability of the B-N-B-substituted benzenoid systems, which are as yet not well known experimentally, shows similar features. We investigated in a preliminary way the reactivity and potential stabilization by substitution of the energetically most stable structures and by examining possible escape routes by dimerization. Our study suggests new N-B-N and B-N-B molecules that could be made. 相似文献
118.
Yu CC Lau C Tunnell JW Hunter M Kalashnikov M Fang-Yen C Fulghum SF Badizadegan K Dasari RR Feld MS 《Optics letters》2006,31(21):3119-3121
We describe azimuthal light scattering spectroscopy (phi/LSS), a novel technique for assessing epithelial-cell nuclear morphology. The difference between the spectra measured at azimuthal angles phi = 0 degrees and phi = 90 degrees preferentially isolates the single backscattering contribution due to large (approximately 10 microm) structures such as epithelial cell nuclei by discriminating against scattering from smaller organelles and diffusive background. We demonstrate the feasibility of using phi/LSS for cancer detection by showing that spectra from cancerous colon tissue exhibit significantly greater azimuthal asymmetry than spectra from normal colonic tissues. 相似文献
119.
Nantalaksakul A Dasari RR Ahn TS Al-Kaysi R Bardeen CJ Thayumanavan S 《Organic letters》2006,8(14):2981-2984
[reaction: see text] We have designed and synthesized difunctionalized dendrimers containing two donors in the periphery and an acceptor at the core to serve as scaffolds for comparison with linear analogues to investigate the advantage of dendritic scaffolds for energy and charge transfer. Comparison of these dendrimers with the fully decorated dendrimers provides information on the advantage of chromophore density in energy/charge transfer from periphery to the core. 相似文献