107,382 research outputs found
Sampling power-law distributions
No full textPower-law distributions describe many phenomena related to rock fracture. Data collected to measure the parameters of such distributions only represent samples from some underlying population. Without proper consideration of the scale and size limitations of such data, estimates of the population parameters, particularly the exponent D, are likely to be biased. A Monte Carlo simulation of the sampling and analysis process has been made, to test the accuracy of the most common methods of analysis and to quantify the confidence interval for D. The cumulative graph is almost always biased by the scale limitations of the data and can appear non-linear, even when the sample is ideally power law. An iterative correction procedure is outlined which is generally successful in giving unbiased estimates of D. A standard discrete frequency graph has been found to be highly inaccurate, and its use is not recommended. The methods normally used for earthquake magnitudes, such as a discrete frequency graph of logs of values and various maximum likelihood formulations can be used for other types of data, and with care accurate results are possible. Empirical equations are given for the confidence limits on estimates of D, as a function of sample size, the scale range of the data and the method of analysis used. The predictions of the simulations are found to match the results from real sample D-value distributions. The application of the analysis techniques is illustrated with data examples from earthquake and fault population studies
Thomas Pickering expresses gratification with the unanimous passage of Resolution 662 at the United Nations
No full textThomas Pickering expresses gratification with the unanimous passage of Resolution 662 at the United Nations and calls for the restoration of the government of Kuwait to status quo after the Iraqi invasion
Impacts of hunter-gatherers on the vegetation history of the eastern vale of pickering, Yorkshire
No full textResearch is undertaken into the vegetation and human impact at three previously un-researched archaeological sites from the eastern Vale of Pickering. The vegetation history is reconstructed from the end of the Windermere Interstadial c. 13,000 (^14)C yr BP until the final Mesolithic c. 5100 (^14)C yr BP. The early Mesolithic human impact on the vegetation is assessed using a three stage statistical test to establish the internal variability in the data as well as background variations in pollen output. The results reveal that humans had a small but significant impact on the vegetation around two of the sites. Pollen preservation at the third site precluded analyses of the impacts of humans on the vegetation. The three-stage test used to test for human impact was quite successful but requires revision before any further use. On the whole the tests confirmed the findings of conventional human impact analyses. During the pre-Holocene fires occurred on a regular basis. These fires varied in location and intensity, suggesting that some of the fires were regional or large-scale, whilst others were small and very localized. A multi-causal explanation has been given for the fires. Later, during the early Mesolithic, human groups are thought to have burnt the reedswamp at the lake edges as part of an economic strategy. Star Carr is the only site that demonstrates clearance of significant areas of woodland. During the later Mesolithic the hunter-gatherers have a greater impact on the vegetation within the Vale. This is attributed to the need for more resources as a result of vegetation change and increased population levels. Unlike their counter-parts from the North York Moors, the occupants of the lowland Vale of Pickering cause no long-term change to their environment
Cyclodextrin-Based Pickering Emulsion Significantly Increases 6-Gingerol Loading Through Two Different Mechanisms: Cyclodextrin Cavity and Pickering Core
No full textWe previously found that host–guest interactions can drive gingerols (Gs) and cyclodextrins (CDs) together to form inclusion complexes (G/CD), which can further construct amphiphilic microcrystals and resultant Pickering emulsions through self-assembly. In this follow-up study, we explored the detailed formation processes and mechanisms of the 6-G/β-CD inclusion complex and the resultant Pickering emulsion. The influence of the 6-G/β-CD molar ratio on the structure, morphology, and loading capacity of the inclusion complex and resultant Pickering emulsion were investigated. The results show that the cyclodextrin-based Pickering emulsion can load 6-G in two places; one place is the cyclodextrin cavity, whose loading capacity is up to 9.28%, while the other one is the Pickering core, with its highest loading capacity at 32.31% when the 6-G/β-CD molar ratio is 5:1. In the above case, the 6-G/β-CD inclusion complex was found to form a unit cell with a 1:2 molar ratio and then self-assemble into amphiphilic microcrystals through cage-type arrangement structures at the oil–water interface, mainly driven by van der Waals forces and hydrogen bonds. This study is helpful in the design and preparation of CD-based high-loading carriers for bioactive compound delivery
Pickering, James D.
No full text"Chinkapin Oak, Quercus muehlenbergii." In memory of Dr. James D. Pickering Professor of English 1954-1988 Dean of the College 1970 - 1975 Beloved Mentor and Friend Given by Stephen G. Masciocchi '80Gift in MemoryTree; Plaque198
Pickering Emulsion Gel Based on Funori Biopolymer and Halloysite Nanotubes: A New Sustainable Material for the Cleaning of Artwork Surfaces
No full textWithin the cultural heritage field, colloidal systems based on ecofriendly products represent alternatives to toxic solvents as cleaners for surface artworks. In this paper, we developed an innovative protocol to prepare a Pickering emulsion gel based on Funori biopolymer, halloysite clay nanotubes (HNTs), and isooctane as confined oil phase. The filling of oil droplets within the Funori network might reduce the amounts of hydrocarbons necessary for surface cleaning applications. Moreover, the specific interactions between Funori biopolymer and halloysite stabilized isooctane droplets could increase the colloidal stability of the Pickering emulsions and favor the removal efficiency toward hydrophobic contaminants. First, we optimized the preparation of Funori gel in aqueous media by the addition of variable amounts of Ba2+ ions as cross-linkers. To this purpose, we studied the biopolymer cross-linking process by the investigation of the rheological properties and the gelation kinetics. Then, we prepared a hybrid gel based on Funori and Pickering emulsions stabilized by HNTs to achieve sustainable materials with hydrophobic microdomains that are useful for surface cleaning applications. We investigated the colloidal stability and the rheological properties, which were strictly correlated to the specific Funori/halloysite interactions. The peculiar effects of Funori on the HNTs Pickering emulsion were assessed by studying the energetics of detaching of halloysite at isooctane/water interface. Remarkably, the presence of the biopolymer enhanced the interfacial activity of HNTs and, consequently, the colloidal stability of the Pickering emulsion. Finally, we explored the surface cleaning efficiency of the Pickering emulsion gel toward Regalrez 1126, which is a hydrophobic contaminant that can be found on artworks. Remarkably, both contact angle measurements and optical investigations revealed a complete removal of Regalrez 1126 from the surface after 2 min of gel application. Further cleaning tests on a real artwork (an oil on canvas coming from a private collection) confirmed the suitability of the Funori/HNTs/isooctane gel for restoration purposes
Sonny Montgomery, Hank Moseley, and Chip Pickering
No full textPhotograph of Sonny Montgomery, Hank Moseley, and Chip Pickering at a Mississippi State University football gamehttps://scholarsjunction.msstate.edu/gvm-photographs/1298/thumbnail.jp
Pickering Emulsion Gels Based on Halloysite Nanotubes and Ionic Biopolymers: Properties and Cleaning Action on Marble Surface
No full textWe have fabricated ecocompatible Pickering emulsions based on halloysite nanotubes and ionic biopolymers (chitosan and pectin) from renewable resources. The effect of pectin and chitosan on the Pickering emulsion was investigated by direct visualization of the oil droplets and by the thermodynamic characterization at the interface. Pectin enhances the Pickering emulsion stability, while a phase separation and nonhomogeneous gel was observed in the presence of chitosan. We have demonstrated that the Pickering emulsion in a pectin based gel phase is suitable for wax layer removal from a marble surface. A controlled cleaning is achieved by tuning the contact time between the gel and the marble surface. Due to its nonhomogeneous structure, chitosan-based gel does not show proper wax removal ability. This work opens up a new sustainable approach in preparing cleaning formulations for conservation of cultural heritage
Fault populations and their relationship to the scaling of surface roughness
No full textThe relationship between the scaling properties of faulted geological surfaces and parameters describing the underlying fault population are investigated using simulations of a dip?slip faulted surface. Analysis of multiple simulations of sections through the surface allowed the construction of a statistical relationship between the parameters defining the fault population and the fractal dimension of the surface. The results indicate a direct, if complex, relationship between the fault population and the scaling of the surface roughness. The main determining factor is the displacement distribution, with spacing and dip having only a minor contribution. This relationship is tested against examples from the Moray Firth, Scotland, and the central Indian Ocean.<br/
Pickering Emulsions Stabilized by Halloysite Nanotubes: From General Aspects to Technological Applications
No full textBesides surfactants, which decrease the interfacial tension between two immiscible liquids, also interfacially active particles can successfully stabilize an emulsion system by attaching at the liquid–liquid interface. The preparation of the resulting Pickering emulsions has been so far investigated starting from the study of the interactions arising between the dispersed droplets and the stabilizers, till the application of these systems in a wide range of different fields. This work is intended to provide an overall overview about the development of Pickering emulsions by considering the most general aspects and scanning the diverse types of solid stabilizers. Among them, Halloysite nanotubes play a major role as naturally derived clay with emulsifying capability owing to their cheap, abundant, green and biocompatible properties. Therefore, the design of Halloysite stabilized Pickering emulsions is the main content of this review, which will survey the role of nanotubes in providing colloidal stability and will comprehensively sum up the use of these particles in technological and industrial purposes: from environmental to catalytic, from health to cultural heritage related applications
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