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71.
New techniques are presented that make phase-shifting holography viable for second-harmonic generation (SHG) holography with weak object fields. We developed an intrinsic phase shift calibration of SHG holograms, an algorithm that extracts the reference and object intensity directly from a set of phase-shifted holographic data, and a more robust phase-shifting holography reconstruction algorithm based on π-shifted hologram pairs that permits self-calibration of the phase shift and recovery of the complex field through a Hilbert transform. 相似文献
72.
Normal phase high performance liquid chromatography (HPLC) is used to separate a gas oil petroleum sample, and the fractions are collected offline and analyzed on a high resolution Fourier Transform Ion Cyclotron Resonance Mass Spectrometer (FT-ICR MS). The separation prior to MS analysis dilutes the sample significantly; therefore the fractions need to be prepared properly to achieve the best signal possible. The methods used to prepare the HPLC fractions for MS analysis are described, with emphasis placed on increasing the concentration of analyte species. The dilution effect also means that contamination in the MS spectra needs to be minimized. The contamination from molecular sieves, plastics, soap, etc. and interferences encountered during the offline fraction collection process are described and eliminated. A previously unreported MS contamination of iron formate clusters with a 0.8 mass defect in positive mode electrospray is also described. This interference resulted from the stainless steel tubing in the HPLC system. Contamination resulting from what has tentatively been assigned as palmitoylglycerol and stearoylglycerol was also observed; these compounds have not previously been reported as contaminant peaks. 相似文献
73.
KP Nacheva WA Maza DZ Myers FR Fronczek RW Larsen R Manetsch 《Organic & biomolecular chemistry》2012,10(38):7840-7846
A fluorescent compound 3,4-bis(2,4-difluorophenyl)-maleimide from the 3,4-diaryl-substituted maleimides was synthesized and determined to have a Stokes shift of 140 nm (λ(abs) 341 nm, λ(em) 481 nm), a high fluorescent quantum yield (Φ(fl) 0.61) and an extinction coefficient ε((340)) of 48?400 M(-1) cm(-1) in dichloromethane. For the first time we demonstrated the successful implementation of a 3,4-diaryl-substituted maleimide molecule as a donor component in FRET experiments. 相似文献
74.
Chen ZW Chen LH Akentieva N Lichti CF Darbandi R Hastings R Covey DF Reichert DE Townsend RR Evers AS 《Electrophoresis》2012,33(4):666-674
Previous studies have shown that the neurosteroid analogue, 6-Azi-pregnanolone (6-AziP), photolabels voltage-dependent anion channels and proteins of approximately 55 kDa in rat brain membranes. The present study used two-dimensional electrophoresis and nanoelectrospray ionization ion-trap mass spectrometry (nano-ESI-MS) to identify the 55 kDa proteins (isoelectric point 4.8) as isoforms of β-tubulin. This identification was confirmed by immunoblot and immunoprecipitation of photolabeled protein with anti-β-tubulin antibody and by the demonstration that 6-AziP photolabels purified bovine brain tubulin in a concentration-dependent pattern. To identify the photolabeling sites, purified bovine brain tubulin was photolabeled with 6-AziP, digested with trypsin, and analyzed by matrix-assisted laser desorption/ionization MS (MALDI). A 6-AziP adduct of TAVCDIPPR(m/z?= 1287.77), a β-tubulin specific peptide, was detected by MALDI. High-resolution liquid chromatography-MS/MS analysis identified that 6-AziP was covalently bound to cysteine 354 (Cys-354), previously identified as a colchicine-binding site. 6-AziP photolabeling was inhibited by 2-methoxyestradiol, an endogenous derivative of estradiol thought to bind to the colchicine site. Structural modeling predicted that neurosteroids could dock in this colchicine site at the interface between α- and β-tubulin with the photolabeling group of 6-AziP positioned proximate to Cys-354. 相似文献
75.
Worland R 《The Journal of the Acoustical Society of America》2012,131(1):935-944
An experimental investigation of orchestral crotale vibrational modes in water is presented, along with a qualitative virtual mass model describing the observed effects. Changes in frequency, overtone ratio, and mode splitting as a function of water depth are reported for a C(6) crotale using electronic speckle-pattern interferometry. These data are related to perceived changes in pitch and timbre, along with the creation of audible beats at particular water depths. It is also shown that the suspension method used by musicians when dipping crotales into water leads to the creation of additional acoustically significant modes that are not excited when the crotales are mounted in the standard manner. 相似文献
76.
Dr. Hua Yang Dr. Chengcheng Zhang Dr. Zheliang Yuan Dr. Cristina Rodriguez-Rodriguez Andrew Robertson Dr. Valery Radchenko Randy Perron Denise Gendron Dr. Patrick Causey Dr. Feng Gao Dr. François Bénard Dr. Paul Schaffer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(50):11435-11440
Targeted alpha-therapy (TAT) has great potential for treating a broad range of late-stage cancers by delivering a focused and lethal radiation dose to tumors. Actinium-225 (225Ac) is an emerging alpha emitter suitable for TAT; however, the availability of chelators for Ac remains limited to a small number of examples (DOTA and macropa). Herein, we report a new Ac macrocyclic chelator named ‘ crown’ , which binds quantitatively and rapidly (<10 min) to Ac at ambient temperature. We synthesized 225Ac- crown -αMSH, a peptide targeting the melanocortin 1 receptor (MC1R), specifically expressed in primary and metastatic melanoma. Biodistribution of 225Ac- crown -αMSH showed favorable tumor-to-background ratios at 2 h post injection in a preclinical model. In addition, we demonstrated dramatically different biodistrubution patterns of 225Ac- crown -αMSH when subjected to different latency times before injection. A combined quality control methodology involving HPLC, gamma spectroscopy and radioTLC is recommended. 相似文献
77.
78.
Fred Glover Randy Glover Frederick K. Martinson 《The Journal of the Operational Research Society》1984,35(7):605-616
We report an effective model and solution procedure for a major resource management problem of the U.S. Bureau of Land Management (B.L.M.), enabling large practical applications to be solved 20-300 times faster than previously possible. The resulting system has proved a useful analysis tool, providing model interaction capabilities that are employed routinely by the B.L.M. an average of 700 times a month throughout the U.S. 相似文献
79.