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91.
When fielders catch fly balls they use geometric properties to optically maintain control over the ball. The strategy provides ongoing guidance without indicating precise positional information concerning where the ball is located in space. Here, the authors show that observers have striking misconceptions about what the motion of projectiles should look like from various perspectives and that they estimate when the physical apex of a fly ball occurs to be far later than actual, irrespective of baseball experience. Their estimations are consistent with the highest point they are looking at as the ball approaches, not with the physical apex. These findings introduce a new and robust effect in intuitive perception in which people confuse their perceptual perspective with the physical situation that they mentally represent. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
92.
Experimental observations have been made of the fringe contrast which appears at the terminating edges of thin objects in defocused, scanning-transmission electron micrographs. In general only a single bright fringe is present and the displacement and width of this fringe was found to vary linearly with defocus, indicating the contrast does not result from simple-Fresnel diffraction. A model for this contrast, based on the refraction of incident electrons by the object edge, is shown to explain the observed results. 相似文献
93.
Nitrogen base fractions were prepared from a heavy coal-derived liquid via two commonly accepted laboratory procedures and partially characterized. Significant differences in the composition of the two fractions suggest strongly that extreme caution should be exercised in interpreting and comparing the results of base characterization studies in which different base isolation procedures are used. 相似文献
94.
Damir Dennis Torrico Wisdom Wardy Kennet Mariano Carabante Kairy Dharali Pujols Zhimin Xu Hong Kyoon No Witoon Prinyawiwatkul 《LWT》2014
Effects of mineral oil:chitosan (MO:CH at 25:75) emulsions prepared with four different emulsifiers (2 water- and 2 oil-miscible) as coatings on the internal quality (weight loss, Haugh unit, yolk index, and albumen pH) of coated eggs were evaluated during 5 weeks at 25 ± 2 °C and 20 weeks at 4 ± 2 °C. Eggs with two initial albumen qualities [Haugh unit (HU): H = 87.8 and L = 70.9] were used. At 25 ± 2 °C, Haugh unit, yolk index, and albumen pH of all coated eggs decreased with increased storage time. Coated H- and L-eggs maintained an A-grade up to 4 weeks and 1 week, respectively. Weight loss of all coated eggs remained below 1.35% after 5 weeks of storage at 25 ± 2 °C. All coated eggs maintained an A-grade with less than 2.5% weight loss during 20 weeks of storage at 4 ± 2 °C. Emulsifier types marginally affected the internal quality of coated eggs regardless of storage temperatures. 相似文献
95.
Patrick C. Aculey Pia Snitkjaer Margaret Owusu Marc Bassompiere Jemmy Takrama Lars Nørgaard Mikael A. Petersen Dennis S. Nielsen 《Journal of food science》2010,75(6):S300-S307
Abstract: Export of cocoa beans is of great economic importance in Ghana and several other tropical countries. Raw cocoa has an astringent, unpleasant taste, and flavor, and has to be fermented, dried, and roasted to obtain the characteristic cocoa flavor and taste. In an attempt to obtain a deeper understanding of the changes in the cocoa beans during fermentation and investigate the possibility of future development of objective methods for assessing the degree of fermentation, a novel combination of methods including cut test, colorimetry, fluorescence spectroscopy, NIR spectroscopy, and GC-MS evaluated by chemometric methods was used to examine cocoa beans sampled at different durations of fermentation and samples representing fully fermented and dried beans from all cocoa growing regions of Ghana. Using colorimetry it was found that samples moved towards higher a* and b* values as fermentation progressed. Furthermore, the degree of fermentation could, in general, be well described by the spectroscopic methods used. In addition, it was possible to link analysis of volatile compounds with predictions of fermentation time. Fermented and dried cocoa beans from the Volta and the Western regions clustered separately in the score plots based on colorimetric, fluorescence, NIR, and GC-MS indicating regional differences in the composition of Ghanaian cocoa beans. The study demonstrates the potential of colorimetry and spectroscopic methods as valuable tools for determining the fermentation degree of cocoa beans. Using GC-MS it was possible to demonstrate the formation of several important aroma compounds such 2-phenylethyl acetate, propionic acid, and acetoin and the breakdown of others like diacetyl during fermentation. Practical Application: The present study demonstrates the potential of using colorimetry and spectroscopic methods as objective methods for determining cocoa bean quality along the processing chain. Development of objective methods for determining cocoa bean quality will be of great importance for quality insurance within the fields of cocoa processing and raw material control in chocolate producing companies. 相似文献
96.
Analysis of lagoon samples from different concentrated animal feeding operations for estrogens and estrogen conjugates 总被引:3,自引:0,他引:3
Although Concentrated Animal Feeding Operations (CAFOs) have been identified as potentially important sources for the release of estrogens into the environment, information is lacking on the concentrations of estrogens in whole lagoon effluents (including suspended solids) which are used for land application. Lagoons associated with swine, poultry, and cattle operations were sampled at three locations each for direct analysis for estrogens by GC/ MS/MS and estrogen conjugates by LC/MS/MS. Estrogen conjugates were also analyzed indirectly by first subjecting the same samples to enzyme hydrolysis. Solids from centrifuged samples were extracted for free estrogens to estimate total estrogen load. Total free estrogen levels (estrone, 17alpha-estradiol, 17beta-estradiol, estriol) were generally higher in swine primary (1000-21000 ng/L), followed by poultry primary (1800-4000 ng/L), dairy secondary (370-550 ng/L), and beef secondary (22-24 ng/L) whole lagoon samples. Swine and poultry lagoons contained levels of 17(alpha-estradiol comparable to those of 17beta-estradiol. Confirmed estrogen conjugates included estrone-3-sulfate (2-91 ng/L), 17beta-estradiol-3-sulfate (8-44 ng/L), 17alpha-estradiol-3-sulfate (141-182 ng/L), and 17beta-estradiol-17-sulfate (72-84 ng/L) in some lagoons. Enzymatic hydrolysis indicated the presence of additional unidentified estrogen conjugates not detected bythe LC/MS/MS method. In most cases estrogen conjugates accounted for at least a third of the total estrogen equivalents. Collectively, these methods can be used to better determine estrogen loads from CAFO operations, and this research shows that estrogen conjugates contribute significantly to the overall estrogen load, even in different types of CAFO lagoons. 相似文献
97.
Daniel Stubba Dr. Dennis Bensinger Janika Steinbacher Lilia Proskurjakov Álvaro Salcedo Gómez Dr. Uwe Schmidt Prof. Dr. Stefan Roth Prof. Dr. Katja Schmitz Prof. Dr. Boris Schmidt 《ChemMedChem》2019,14(23):2005-2022
The ubiquitin-proteasome system (UPS) is an established therapeutic target for approved drugs to treat selected hematologic malignancies. While drug discovery targeting the UPS focuses on irreversibly binding epoxyketones and slowly-reversibly binding boronates, optimization of novel covalent-reversibly binding warheads remains largely unattended. We previously reported α-ketoamides to be a promising reversible lead motif, yet the cytotoxic activity required further optimization. This work focuses on the lead optimization of phenoxy-substituted α-ketoamides combining the structure-activity relationships from the primed and the non-primed site of the proteasome β5 subunit. Our optimization strategy is accompanied by molecular modeling, suggesting occupation of P1′ by a 3-phenoxy group to increase β5 inhibition and cytotoxic activity in leukemia cell lines. Key compounds were further profiled for time-dependent inhibition of cellular substrate conversion. Furthermore, the α-ketoamide lead structure 27 does not affect escape response behavior in Danio rerio embryos, in contrast to bortezomib, which suggests increased target specificity. 相似文献
98.
Jiang-Li Cao Kwang-Leong Choy Hai-Lin Sun Hui-Qing Li Dennis Teer Ming-Dong Bao 《Journal of Coatings Technology and Research》2011,8(2):283-288
Nano-structured superhard coatings represent the state-of-the-art in the rapidly increasing worldwide market for protective
coatings. In this study, the combination of nano-composite and nano-multilayered structures into the same coating was attempted.
Nano-multilayered coatings of TiN/TiSiN and CrN/CrSiN were deposited on tool steel substrates by closed-magnetic-field unbalanced
DC magnetron sputter ion plating. The coating structures were characterized using X-ray diffraction, atomic force microscopy,
and scanning electron microscopy. Mechanical characterizations were performed including nano-hardness measurement, progressively-increasing-load
scratch test, and wear test. TiN/TiSiN coatings have a nano-hardness of 40.2 GPa, whereas CrN/CrSiN coatings have a hardness
of 30.9 GPa. TiN/TiSiN coatings also showed a higher critical failure force and scratch fracture toughness as well as better
wear resistance and lower acoustic emission signal, indicating less total damage to the coatings. 相似文献
99.
To address issues concerning the global environmental and energy state, new catalytic technologies must be developed that translate ambient and efficient conditions to heavily used reactions. To achieve this, the structure/function relationship between model catalysts and individual reactions must be critically discerned to identify structural motifs responsible for the reactivity. This is especially true for nanoparticle-based systems where this level of information remains limited. Here we present evidence indicating that peptide-capped Pd nanoparticles drive Stille C-C coupling reactions via Pd atom leaching. Through a series of reaction studies, the materials are shown to be optimized for reactivity under ambient conditions where increases in temperature or catalyst concentration deactivate reactivity due to the leaching process. A quartz crystal microbalance analysis demonstrates that Pd leaching occurs during the initial oxidative addition step at the nanoparticle surface by aryl halides. Together, this suggests that peptide-based materials may be optimally suited for use as model systems to isolate structural motifs responsible for the generation of catalytically reactive materials under ambient synthetic conditions. 相似文献
100.
Darrin M. Haagenson Dennis P. Wiesenborn 《Journal of the American Oil Chemists' Society》2011,88(9):1439-1445
Canola biodiesel (fatty acid methyl esters, FAME) may have superior cold flow properties when compared to other biodiesel
feedstocks, which is attributed to canola’s high unsaturated and low saturated fat content. The objective of this study was
to evaluate canola biodiesel fatty acid composition, cloud point (CP) and oil stability index (OSI) among several ND locations
and production years. In Experiment 1, bulked canola varieties from seven growing seasons (2003–2009) were analyzed and in
Experiment 2 a single canola variety (Interstate Hyola 357RR) harvested at two locations (2003–2005, and 2007) were analyzed.
FAME was produced directly from seed via in situ alkaline transesterification methods. CP ranged from −0.1 to −2.4 °C and
was significantly impacted by year and location. FAME generally met the ASTM B100 specification for OSI (3 h), but increased
seed storage decreased stability. No significant differences were detected in FAME composition, and iodine value ranged from
108 to 123 g I2/100 g. A significant relationship between fat saturation and location with CP and stability was not detected among the samples
in this study. Variation in fatty acid composition was small; thus, the significant variability in CP and OSI suggests either
differences in minor constituents (antioxidants, waxes) or environmental seed stress impacted biodiesel quality. Our study
supports the value of examining biodiesel quality in a canola breeding program. 相似文献