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1.
Experiments by Gittings, Bandyopadhyay and Durian (Europhys. Lett. 65, 414 (2004)) demonstrate that light possesses a higher probability to propagate in the liquid phase of a foam due to total
reflection. The authors term this observation photon channelling which we investigate in this article theoretically. We first
derive a central relation in the work of Gitting et al. without any free parameters. It links the photon's path-length fraction f in the liquid phase to the liquid fraction ɛ. We then construct two-dimensional Voronoi foams, replace the cell edges by
channels to represent the liquid films and simulate photon paths according to the laws of ray optics using transmission and
reflection coefficients from Fresnel's formulas. In an exact honeycomb foam, the photons show superdiffusive behavior. It
becomes diffusive as soon as disorder is introduced into the foams. The dependence of the diffusion constant on channel width
and refractive index is explained by a one-dimensional random-walk model. It contains a photon channelling state that is crucial
for the understanding of the numerical results. At the end, we shortly comment on the observation that photon channelling
only occurs in a finite range of ɛ. 相似文献
2.
Vivian E. Cornelio Mariele M. Pedroso André S. Afonso João B. Fernandes M.Fátima G.F. da Silva Ronaldo C. Faria Paulo C. Vieira 《Analytica chimica acta》2015
The hemoglobin (Hb) released from erythrocytes is a primary nutritive component for many blood-feeding parasites. The aspartic protease cathepsin D is a hemoglobinase that is involved in the Hb degradation process and is considered an interesting target for chemotherapy intervention. However, traditional enzymatic assays for studying Hb degradation utilize spectrophotometric techniques, which do not allow real-time monitoring and can present serious interference problems. Herein, we describe a biosensor using simple approach for the real-time monitoring of Hb hydrolysis as well as an efficient screening method for natural products as enzymatic inhibitors using a quartz crystal microbalance (QCM) technique. Hemoglobin was anchored on the quartz crystal surface using mixed self-assembled monolayers. The addition of the enzyme caused a mass change (frequency shift) due to Hb hydrolysis, which was monitored in real time. From the frequency change patterns of the Hb-functionalized QCM, we evaluated the enzymatic reaction by determining the kinetic parameters of product formation (kcat). The QCM enzymatic assay using immobilized human Hb was shown to be an excellent approach for screening possible inhibitors in complex mixtures, opening up a new avenue for the discovery of novel inhibitors. 相似文献
3.
MF Miller IA Franchi AS Sexton CT Pillinger 《Rapid communications in mass spectrometry : RCM》1999,13(13):1211-1217
The use of infrared laser-assisted fluorination to release oxygen from milligram quantities of silicates or other oxide mineral grains is a well-established technique. However, relatively few studies have reported the optimisation of this procedure for oxygen-17 isotope measurements. We describe here details of an analytical system using infrared (10 μm) laser-assisted fluorination, in conjunction with a dual inlet mass spectrometer of high resolving power ( approximately 250) to provide (17)O and (18)O oxygen isotope measurements from 0.5-2 mg of silicates or other oxide mineral grains. Respective precisions (1) of typically 0.08 and 0.04 per thousand are obtained for the complete analytical procedure. Departures from the mass-dependent oxygen isotope fractionation line are quantified by Delta(17)O; our precision (1) of such measurements on individual samples is shown to be +/-0.024 per thousand. In turn, this permits the offset between parallel, mass-dependent fractionation lines to be characterised to substantially greater precision than has been possible hitherto. Application of this system to investigate the (17)O versus (18)O relationship for numerous terrestrial whole-rock and mineral samples, of diverse geological origins and age, indicates that the complete data set may be described by a single, mass-dependent fractionation line of slope 0.5244+/- 0.00038 (standard error). Copyright 1999 John Wiley & Sons, Ltd. 相似文献
4.
CM Silva MF Duarte ML Mira MH Florêncio K Versluis AJ Heck 《Rapid communications in mass spectrometry : RCM》1999,13(12):1098-1103
Fast atom bombardment, combined with high-energy collision-induced tandem mass spectrometry, has been used to investigate gas-phase metal-ion interactions with captopril, enalaprilat and lisinopril, all angiotensin-converting enzyme inhibitors.Suggestions for the location of metal-binding sites are presented. For captopril, metal binding occurs most likely at both the sulphur and the nitrogen atom. For enalaprilat and lisinopril, binding preferably occurs at the amine nitrogen. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
5.
6.
Scott D. Hanton Paula A. Cornelio Clark Kevin G. Owens 《Journal of the American Society for Mass Spectrometry》1999,10(2):104-111
Matrix-assisted laser desorption/ionization (MALDI) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) analyses are compared to gain insight into some of the details of sample preparation for MALDI analysis of synthetic polymers. ToF-SIMS imaging of MALDI samples shows segregation of the cationization agent from the matrix crystals. The amount of observed segregation can be controlled by the sample preparation technique. Electrospray sample deposition minimizes segregation. Comparing ToF-SIMS and MALDI mass spectra from the same samples confirms that ToF-SIMS is significantly more surface sensitive than MALDI. This comparison shows that segregation of the oligomers of a polymer sample can occur during MALDI sample preparation. Our data indicate that MALDI is not as sensitive to those species dominating the sample surface as to species better incorporated into the matrix crystals. Finally, we show that matrix-enhanced SIMS can be an effective tool to analyze synthetic polymers, although the sample preparation conditions may be different than those optimized for MALDI. 相似文献
7.
The effects on the radiation response of Harwell polymethylmethacrylate (PMMA) dosimeters of dose-rate, radiation type, temperature during irradiation and post-irradiation storage, and post-irradiation stability, are of importance to the operators of commercial irradiation facilities.
This paper describes recent studies of the effects of some of these parameters on the radiation response of Harwell Red 4034, Amber 3042, and Gammachrome YR Perspex dosimeters, and provides data on batch to batch variation and shelf-life. 相似文献
8.
Cornelio Doelter 《Monatshefte für Chemie / Chemical Monthly》1929,52(1):241-252
9.
Murali S Dreyer DR Valle-Vigón P Stoller MD Zhu Y Morales C Fuertes AB Bielawski CW Ruoff RS 《Physical chemistry chemical physics : PCCP》2011,13(7):2652-2655
The performance of mesoporous carbon capsules as electrode materials in electrochemical double layer capacitors (EDLCs) was evaluated in the presence of a variety of electrolytes, including room temperature ionic liquids (ILs). 相似文献
10.
Geyer Andrea Renata Cornelio Sousa Varley Dias Silveira Dâmaris 《Accreditation and quality assurance》2019,24(5):351-360
Accreditation and Quality Assurance - Good manufacturing practices (GMP) ensure that products are consistently produced and controlled according to appropriate quality standards. This study aimed... 相似文献