The complex shear modulus of dough over a wide frequency range     

Valentin Leroy  Karen M. Pitura  Martin G. Scanlon  John H. Page 《ournal of non Newtonian Fluid Mechanics》2010,165(9-10):475-478

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Adam J. Wright;David L. Hughes;Phillip C. Bulman Page;G. Richard Stephenson; 《European journal of organic chemistry》2019,2019(43):7186-7186

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Zachariah A. Page  Feng Liu  Thomas P. Russell  Todd Emrick 《Journal of polymer science. Part A, Polymer chemistry》2015,53(2):327-336

Narrow band gap conjugated polymer zwitterions (CPZs) were synthesized by Suzuki polymerization and characterized to understand their electronic properties and utility as cathode modification layers in solar cells. The polymers were prepared from diketopyrrolopyrrole (DPP) and iso-indigo monomers containing sulfobetaine (SB) pendant groups, benefiting from an ion-rich aqueous phase in the polymerizations. UV–vis absorption spectroscopy revealed the optical energy gap value for the CPZs, ranging from 1.7 to 1.2 eV. Ultraviolet photoelectron spectroscopy of the CPZs as thin layers on Ag metal showed that the pendent zwitterions impart an interfacial dipole (Δ) to the metal and a work function reduction of ∼0.9 eV. OPVs fabricated using a conventional bulk heterojunction (BHJ) device architecture of ITO/PEDOT:PSS/(PTB7:PC₇₁BM)/CPZ/Ag led to dramatic improvements in power conversion efficiency (PCE) values relative to devices having bare Ag cathodes (PCE < 2% for bare Ag vs. 6.7–7.7% for CPZ/Ag). The benzothiadiazole (BT)/DPP polymer denoted as PT₂BTDPPSB gave an optimal PCE of 7.7% in a conventional BHJ OPV device architecture fabricated on a Ag cathode. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 327–336  相似文献   

    

Sunil Rana  Robin H Page  Calum J. McNeil 《Electroanalysis》2011,23(10):2485-2490

It has been reported that the introduction of a dielectric barrier between adjacent digits of an interdigitated electrode array can improve the sensitivity of the array as an electrochemical impedance biosensor. Here we present an in‐depth analysis of the impedance in planar interdigitated electrodes and 3‐D interdigitated electrodes (with dielectric barriers). The analysis indicates that the planar geometry not only provides lower impedance but also a higher change impedance as a result of molecular immobilization on the electrode array surface.  相似文献   

    

Xiaohang Zhang  Christopher A. Paddon  Yohan Chan  Philip C. Bulman‐Page  Paul S. Fordred  Steven D. Bull  Ho‐Chol Chang  Nadeem Rizvi  Frank Marken 《Electroanalysis》2009,21(12):1341-1347

Mineral oil microdroplets containing the model antioxidant N,N‐didodecyl‐N′,N′‐diethyl‐phenylene‐diamine (DDPD) are immobilized into a 100×100 pore‐array (ca. 10 μm individual pore diameter, 100 μm pitch) in a boron‐doped diamond electrode surface. The robust diamond surface allows pore filling, cleaning, and reuse without damage to the electrode surface. The electrode is immersed into aqueous electrolyte media, and voltammetric responses for the oxidation of DDPD are obtained. In order to further improve the current responses, 20 wt% of carbon nanofibers are co‐deposited with the oil into the pore array. Voltammetric signals are consistent with the oxidation of DDPD and the associated transfer of perchlorate anions (in aqueous 0.1 M NaClO₄) or the transfer of protons (in aqueous 0.1 M HClO₄). From the magnitude of the current response, the DDPD content in the mineral oil can be determined down to less than 1 wt% levels. Perhaps surprisingly, the reversible (or midpoint) potential for the DDPD oxidation in mineral oil (when immersed in 0.1 NaClO₄) is shown to be concentration‐dependent and to shift to more positive potential values for more dilute DDPD in mineral oil solutions. An extraction mechanism and the formation of a separate organic product phase are proposed to explain this behavior.  相似文献   

    

Kumauchi M  Hara MT  Stalcup P  Xie A  Hoff WD 《Photochemistry and photobiology》2008,84(4):956-969

Photoactive yellow proteins (PYP) are bacterial photoreceptors with a Per-Arnt-Sim (PAS) domain fold. We report the identification of six new PYPs, thus nearly doubling the size of this protein family. This extends the taxonomic diversity of PYP-containing bacteria from photosynthetic to nonphotosynthetic bacteria, from aquatic to soil-dwelling organisms, and from Proteobacteria to Salinibacter ruber from the phylum Bacteriodetes. The new PYPs greatly increase the sequence diversity of the PYP family, reducing the most prevalent pair-wise identity from 45% to 25%. Sequence alignments and analysis indicate that all 14 PYPs share a common structure with 13 highly conserved residues that form the chromophore binding pocket. Nevertheless, the functional properties of the PYPs vary greatly--the absorbance maximum extends from 432 to 465 nm, the pK(a) of the chromophore varies from pH 2.8 to 10.2, and the lifetime of the presumed PYP signaling state ranges from 1 ms to 1 h. Thus, the PYP family offers an excellent opportunity to investigate how functional properties are tuned over a wide range, while maintaining the same overall protein structural fold. We discuss the implications of these results for structure-function relationships in the PYP family.  相似文献   

    

Keith C. Gordon  Anthony K. Burrell  Timothy J. Simpson  Simon E. Page  Geoffrey Kelso  Matthew I. J. Polson  Amar Flood 《欧洲无机化学杂志》2002,2002(3):554-563

The resonance Raman and infrared spectra of the bridging ligand 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine (bptz) have been studied. Ab initio calculations on bptz and the radical anion bptz ^·− are able to predict the frequencies and intensities of the vibrational spectra. This analysis is used to interpret the vibrational spectroscopy of the bridged binuclear complexes [(bpy)₂Ru(μ-bptz)Ru(bpy)₂]⁴⁺ ( 1 ) and [(PPh₃)₂Cu(μ-bptz)Cu(PPh₃)₂]²⁺ ( 2 ) and their redox products. The resonance Raman spectroscopy of 1 reveals the bichromophoric nature of the complex, with bpy and bptz ligand modes being enhanced selectively as a function of excitation wavelength. The UV/Vis spectrum of 1 ⁺ reveals a strong IVCT band suggesting the mixed-valent species is Class III in nature. This is consistent with findings for other metal moieties with the bptz ligand. The resonance Raman spectrum of 1 ⁺ is also consistent with a Class III formulation. The resonance Raman spectrum of 2 ⁻ is used to model bptz ^{· −} and the ab initio calculations show some correlation with the observed spectrum. The excited-state resonance Raman spectra of 1 , generated with 532 and 633 nm excitation, show spectral features that are not strongly characteristic of bptz ^·− . This appears to be a consequence of the delocalised nature of the molecular orbitals involved in the excited-state of 1 .  相似文献   

    

Neil A. Caplan  Frederick E. Hancock  Philip C. Bulman Page  Graham J. Hutchings 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2004,116(13):1717-1720

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Page JS  Tolmachev AV  Tang K  Smith RD 《Journal of mass spectrometry : JMS》2005,40(9):1215-1222

An adjustable low-mass filter has been developed for an electrospray ionization (ESI) source to block ions associated with unwanted background species from entering the mass spectrometer. The low-mass filter is made by using an adjustable potential energy barrier from the conductance-limiting plate of an electrodynamic ion funnel, which prohibits species with higher ion mobilities from exiting the ESI source. We show that this arrangement provides a linear voltage adjustment for low-mass filtering from m/z 0 to 500. Mass filtering above m/z 500 is also performed; however, higher-mass species are attenuated. The mass filter was tested with a liquid chromatography/mass spectrometry (LC/MS) analysis of a bovine serum albumin (BSA) tryptic digest and resulted in the ability to block low-mass, background species, which accounted for 40-70% of the total ion current immediately behind the ESI source during peak elution and detection.  相似文献   

  总被引：4，自引：0，他引：4  

Kalhorn TF  Page ST  Howald WN  Mostaghel EA  Nelson PS 《Rapid communications in mass spectrometry : RCM》2007,21(19):3200-3206

A sensitive liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) method for the simultaneous quantitative analysis of dihydrotestosterone (DHT) and testosterone (T) from biological fluids has been developed. Commercially available deuterated analogues were used as internal standards. Steroids were extracted from serum or testicular fluid with hexane/ethyl acetate, evaporated to dryness, and treated with hydroxylamine to form their oxime derivatives. Upon chromatographic separation, the compounds were quantified using selected reaction monitoring (SRM). For T, the [M+H](+) ion at m/z 304 and the fragment ion at m/z 124 were used as the precursor and product ions. For DHT the ion cluster [M+H+ACN](+) at m/z 347 and the dissociated ion [M+H](+) at m/z 306 were used as the precursor and product ions, respectively. The limits of detectability on-column were in the sub-femtomole range for both compounds and the intra-day coefficient of variation (CV) for analysis from serum was less than 7% for both compounds. Given its high reproducibility, sensitivity, and relative simplicity, this assay should be of use in determining androgen levels in biospecimens, particularly in settings where sample quantity or steroid concentration are low.  相似文献