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71.
Here we use nuclear magnetic resonance to measure the solubility limit of several biologically relevant sterols in electroformed giant unilamellar vesicle membranes containing phosphatidylcholine (PC) lipids in ratios of 1:1:X DOPC:DPPC:sterol. We find solubility limits of cholesterol, lanosterol, ergosterol, stigmasterol, and β-sitosterol to be 65-70%, ~35%, 30-35%, 20-25%, and ~40%, respectively. The low solubilities of stigmasterol and β-sitosterol, which differ from cholesterol only in their alkyl tails, show that subtle differences in tail structure can strongly affect sterol solubility. Below the solubility limits, the fraction of sterol to PC-lipid in electroformed vesicles linearly reflects the fraction in the original stock solutions used in the electroformation process. 相似文献
72.
Simone Fujii Ricardo Marcelo Reche Ribeiro Maria Brígida Dos Santos Scholz Elisabete Yurie Sataque Ono Cássio Egidio C Prete Eiko Nakagawa Itano Yoshio Ueno Osamu Kawamura Elisa Yoko Hirooka 《Food Additives & Contaminants》2006,23(9):902-909
The performance of an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) based on a monoclonal antibody (mAb) for ochratoxin A (OTA) detection was evaluated in a comparative study with high-performance liquid chromatography (HPLC) analysis using 68 freshly harvested coffee samples from the North of Paraná State, Brazil. The anti-OTA mAb showed high specificity and low cross-reactivity with OTA analogues (OTB and OTalpha), but cross-reacted with OTC. This ic-ELISA showed a detection limit of 3.75 ngg-1 sample, when compared to 0.80 ngg-1 by HPLC, with an ic-ELISA/HPLC correlation coefficient of 0.90. As regards OTA analysis of these coffee samples, natural contamination was detected in 10 samples (14.7%) by both methods, where the ic-ELISA values (range 3.9-7.3 ngg-1) were 1.1 to 1.6-fold higher than HPLC data (2.7-4.7 ngg-1). Five samples (7.4%) were OTA positive (range 0.84-1.30 ngg-1) only by HPLC assay, probably due to the higher detection limit reached by ic-ELISA. OTA was undetectable in 53 samples (77.9%) by both methods, while all positive samples (range 0.84-7.30 ngg-1) showed OTA levels lower than 8 ngg-1 (maximum limit recommended by the European Union). The matrix interference of green coffee was minimized by dilution of sample extracts before carrying out the ELISA assay. This mAb-based ic-ELISA can be effectively applied for OTA screening in coffee, because it is simple, sensitive and sample preparation is easy. 相似文献
73.
Elisa Barney Smith David Monn Harsha Veeramachaneni Koichi Kise Alessio Malizia Leon Todoran Adnan El-Nasan Rolf Ingold 《International Journal on Document Analysis and Recognition》2003,6(3):200-206
This document is a collection of four working group reports in the areas of digital libraries, document image retrieval, layout analysis, and Web document analysis. These reports were the outcome of discussions by participants at the Fifth IAPR International Workshop on Document Analysis Systems held in Princeton, NJ on 19-21 August 2002.Published online: 16 March 2004 相似文献
74.
There is public concern about the magnitude of the problem of large truck crashes in the US. Fatalities in large truck crashes have not declined much; however, more large trucks are driving more miles than ever before while fatalities per mile driven have dropped substantially. This study examined how the public health burden of large truck crashes versus the risk per unit of travel has changed over 25 years.The present study focused on the US vehicle occupants in fatal crashes involving a large truck during 1975-1999. Occupant fatalities per 100000 population, per 10000 licensed drivers, per 10000 registered trucks and per 100 million vehicle-miles of travel (VMT) were calculated to determine trends in occupant deaths in large truck crashes.In 1999, large truck crashes resulted in 3916 occupant deaths in passenger vehicles and 747 in large trucks. Passenger vehicle occupant deaths in large truck crashes per 100000 population have increased somewhat since 1975 (1.28 in 1975 and 1.44 in 1999). There have been appreciable declines in occupant deaths per truck VMT since 1975, but the percentage reduction has been greater for occupants of large trucks (67%) than for passenger vehicle occupants (43%). However, truck drivers are at elevated risk of dying relative to their numbers in the workforce. Overall large truck involvements in fatal crashes per truck VMT decreased more than passenger vehicle involvements per passenger VMT (PVMT; 68% versus 33% decreases for single-vehicle crashes and 43% versus 23% for multiple-vehicle crashes). Large truck involvement in fatal crashes has dropped substantially when measured per unit of travel, but the public health burden of large truck crashes, as measured by deaths per 100000 population, has not improved over time because of the large increase in truck mileage. Research is needed on measures to better protect both occupants of large trucks and passenger vehicle occupants colliding with them. 相似文献
75.
SiOxCyHz thin films were deposited from hexamethyldisiloxane (HMDSO)/O2 mixtures in a parallel plate, capacitively coupled, RF plasma reactor. Polyethylene terephthalate (PET), Si(1 0 0) wafers and KBr tablets were chosen as substrates. Effect of HMDSO/O2 ratio, total treatment pressure and power input on the properties of the deposited films were investigated. The structure and bondings were studied by means of Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Wettability characteristics of the deposited thin films were investigated by means of water droplet contact angle measurements. Surface morphology was investigated with atomic force microscopy. Barrier properties of the SiOxCyHz thin films were investigated by measuring the water vapour transmission rate of the coated PET substrates. Correlations between the characteristics of the deposited film and their barrier properties were discussed. 相似文献
76.
A culture-independent and two culture-dependent real time (rt-) PCR approaches were developed to quantitatively identify Listeria monocytogenes in raw milk and soft cheeses. The optimised rt-PCR revealed 100% inclusivity and exclusivity. DNA- and cell-based standard curves showed a good linearity of response (R2 ≥ 0.987 and R2 ≥ 0.998, respectively) for five orders of magnitude (39 × 105 – 3 × 100 genome equivalents and 106–101 CFU equivalents, respectively) with about 100% relative accuracy and inter-assay variability ≤0.90%. Up to 1 genome equivalent/and 10 CFU/reaction were quantified in the DNA and cell standard curves, respectively. The rt-PCR was then combined with a liquid- (MPN technique) or a solid- (ALOA and PALCAM) based enumeration. The diagnostic sensitivity of the different approaches was investigated in artificially contaminated raw milk and soft cheeses. The rt-PCR culture-independent approach performed well in raw milk and (with a lower sensitivity) in stracchino cheese-based standard curves. MPN/rt-PCR was the best approach to enumerate low levels of L. monocytogenes in raw milk and stracchino cheese, while the ALOA-based rt-PCR quantification was more effective than the PALCAM-based. These performances were confirmed when 23 real samples of raw milk and soft cheeses by both the rt-PCR approaches were assayed. 相似文献
77.
Roque S. Soares Regina C. C. Monteiro Maria M. R. A. Lima Bogdan A. Sava Mihail Elisa 《Journal of Materials Science》2014,49(13):4601-4611
The crystallization kinetics and phase transformation of a transparent Tb3+-doped lithium–aluminum phosphate glass, prepared by melt quenching, were investigated. The energy associated to the glass transition and the crystallization parameters (activation energy for crystallization and Avrami exponent) were evaluated by different methods using the experimental data obtained by differential thermal analysis performed at different heating rates. Using an isoconversional method to determine the change of the activation energy for crystallization with the fraction of crystallization, it was verified that with the increase in the fraction of crystallization from 0.1 to 0.9, the value of the activation energy decreased slightly from ~370 to ~310 kJ mol?1 and that the Avrami exponent varied from 0.8 to 1, suggesting a surface crystal growth mechanism. Observation of the microstructural evolution of heat-treated glass samples confirmed a surface crystallization process revealing spherulitic crystals constituted mainly by aluminum metaphosphate. 相似文献
78.
The nonspecific preparation that follows a warning stimulus (WS) to speed responding to an impending imperative stimulus (IS) is generally viewed as a strategic, intentional process. An alternative view holds that WS acts as a conditioned stimulus that unintentionally elicits a tendency to respond at the moment of IS presentation as a result of a process of trace conditioning. These views were contrasted as explanatory frameworks for classical effects on reaction time of the duration and intertrial variability of the foreperiod, the interval between WS and IS. It is shown that the conditioning view accounts for the available data at least as well as the strategic view. In addition, the results of 3 experiments provide support for the conditioning view by showing that unintentional contributions to nonspecific preparation can be dissociated from intentional contributions. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
79.
Jose García-Torres Elvira Gómez Elisa Vallés 《Journal of Applied Electrochemistry》2009,39(2):233-240
Cobalt electrodeposits were prepared from an electrolytic bath containing cobalt perchlorate. The effect of different species,
organic (thiourea and sodium gluconate) and inorganic (boric acid), on the crystallographic structure, morphology, magnetic
properties and electrochemical behaviour of cobalt electrodeposits was investigated. Amorphous cobalt, hcp cobalt and a non-usual
primitive cubic cobalt phase were observed depending on the bath composition. Depending on the structure, different morphologies
and magnetic properties were found. Coercivity values of the cobalt coatings ranged from around 15 Oe for amorphous, nodular
deposits to 380 Oe for cobalt coatings showing acicular morphology and hcp structure with a (002) preferred orientation. Knowledge
of the influence of the species on the properties of cobalt makes it possible to obtain tailored cobalt films. 相似文献
80.
Zihong Liu Tommy E. Cousins John J. Lesko Elisa D. Sotelino 《Canadian Metallurgical Quarterly》2008,12(6):660-668
No appropriate provisions from either AASHTO Standard (2002) or AASHTO LRFD (2004) bridge design specifications are available for the design of fiber-reinforced polymer (FRP)-deck-on-steel-superstructure bridges. In this research, a parametric study using the finite-element method (FEM) is conducted to examine two design issues concerning the design of FRP-deck-on-steel-superstructure bridges, namely deck relative deflection and load distribution factor (LDF). Results show that the strip method specified in AASHTO LRFD specification as an approximate method of analysis, can also be applied to FRP decks as a practical method. However, different strip width equations have to be determined by either FEM or experimental methods for different types of FRP decks. In this study, one such equation has been derived for the Strongwell deck. In addition, both FEM results and experimental measurements show that the AASHTO LDF equations for glued laminated timber decks on steel stringers provide good estimations of LDF for FRP-deck-on-steel-superstructure bridges. Finally, it is found that the lever rule can be used as an appropriately conservative design method to predict the LDF of FRP-deck-on-steel-superstructure bridges. 相似文献