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Various Surfaces (various + surface)
Selected AbstractsMultivariate calibration of hyperspectral ,-ray energy spectra for proximal soil sensingEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 1 2007R. A. Viscarra Rossel Summary The development of proximal soil sensors to collect fine-scale soil information for environmental monitoring, modelling and precision agriculture is vital. Conventional soil sampling and laboratory analyses are time-consuming and expensive. In this paper we look at the possibility of calibrating hyperspectral ,-ray energy spectra to predict various surface and subsurface soil properties. The spectra were collected with a proximal, on-the-go ,-ray spectrometer. We surveyed two geographically and physiographically different fields in New South Wales, Australia, and collected hyperspectral ,-ray data consisting of 256 energy bands at more than 20 000 sites in each field. Bootstrap aggregation with partial least squares regression (or bagging-PLSR) was used to calibrate the ,-ray spectra of each field for predictions of selected soil properties. However, significant amounts of pre-processing were necessary to expose the correlations between the ,-ray spectra and the soil data. We first filtered the spectra spatially using local kriging, then further de-noised, normalized and detrended them. The resulting bagging-PLSR models of each field were tested using leave-one-out cross-validation. Bagging-PLSR provided robust predictions of clay, coarse sand and Fe contents in the 0,15 cm soil layer and pH and coarse sand contents in the 15,50 cm soil layer. Furthermore, bagging-PLSR provided us with a measure of the uncertainty of predictions. This study is apparently the first to use a multivariate calibration technique with on-the-go proximal ,-ray spectrometry. Proximally sensed ,-ray spectrometry proved to be a useful tool for predicting soil properties in different soil landscapes. [source] Fabrics with Tunable OleophobicityADVANCED MATERIALS, Issue 21 2009Wonjae Choi A simple "dip-coating" process that imbues oleophobicity to various surfaces that inherently possess re-entrant texture, such as commercially available fabrics, is reported. These dip-coated fabric surfaces exhibit reversible, deformation-dependent, tunable wettability, including the capacity to switch their surface wetting properties (between super-repellent and super-wetting) against a wide range of polar and nonpolar liquids. [source] Molecular Self-Assembled Monolayers and Multilayers for Organic and Unconventional Inorganic Thin-Film Transistor ApplicationsADVANCED MATERIALS, Issue 14-15 2009Sara A. DiBenedetto Abstract Principal goals in organic thin-film transistor (OTFT) gate dielectric research include achieving: (i) low gate leakage currents and good chemical/thermal stability, (ii) minimized interface trap state densities to maximize charge transport efficiency, (iii) compatibility with both p- and n- channel organic semiconductors, (iv) enhanced capacitance to lower OTFT operating voltages, and (v) efficient fabrication via solution-phase processing methods. In this Review, we focus on a prominent class of alternative gate dielectric materials: self-assembled monolayers (SAMs) and multilayers (SAMTs) of organic molecules having good insulating properties and large capacitance values, requisite properties for addressing these challenges. We first describe the formation and properties of SAMs on various surfaces (metals and oxides), followed by a discussion of fundamental factors governing charge transport through SAMs. The last section focuses on the roles that SAMs and SAMTs play in OTFTs, such as surface treatments, gate dielectrics, and finally as the semiconductor layer in ultra-thin OTFTs. [source] Physicochemical properties of Shiga toxigenic Escherichia coliJOURNAL OF APPLIED MICROBIOLOGY, Issue 4 2005L. Rivas Abstract Aims:, To investigate the physicochemical surface properties, such as cellular surface charge, hydrophobicity and electron donor/acceptor potential of a selection of Shiga toxigenic Escherichia coli (STEC) isolates grown in broth and agar culture. Methods and Results:, Cellular surface charge was determined using zeta potential measurements. Hydrophobicity of the isolates was determined using bacterial adhesion to hydrocarbons assay, hydrophobic interaction chromatography and contact angle measurements. Microbial adhesion to solvents was used to determine the electron donor/acceptor characteristics. No differences of surface charge measurements were found between broth and agar grown cultures. Isolates belonging to serogroup O157 and serotypes O26:H11 and O111:H- were significantly (P < 0·05) less negatively charged than other STEC serotypes tested. All strains were hydrophilic with most methods and demonstrated a lower hydrophobicity in agar culture compared with broth culture. All strains demonstrated a strong microbial adhesion to chloroform indicating that STEC possess an electron donor and basic character. A relationship between serogroup O157 and other STEC serotypes was apparent using principal-component analysis (PCA). Conclusions:, Combining the results for physicochemical properties using PCA differentiated between strains belonging to the O157 serogroup and other STEC/non-STEC strains. PCA found similar results for broth and agar grown cultures. Significance and Impact of the Study:, Particular serotypes of STEC possess similar physicochemical properties which may play a role in their pathogenicity or potential attachment to various surfaces. [source] Fibrinolytic Poly(dimethyl siloxane) SurfacesMACROMOLECULAR BIOSCIENCE, Issue 9 2008Hong Chen Abstract PDMS surfaces have been modified to confer both resistance to non-specific protein adsorption and clot lyzing properties. The properties and chemical compositions of the surfaces have been investigated using water contact angle measurements, ATR FT-IR spectroscopy, and XPS. The ability of the PEG component to suppress non-specific protein adsorption was assessed by measurement of radiolabeled fibrinogen uptake from buffer. The adsorption of plasminogen from human plasma to the various surfaces was studied. In vitro experiments demonstrated that lysine-immobilized surfaces with free , -amino groups were able to dissolve fibrin clots, following exposure to plasma and tissue plasminogen activator. [source] The Sources and Fortunes of Piranesi's Archaeological IllustrationsART HISTORY, Issue 4 2002Susan M. Dixon Susan M. Dixon earned her doctorate from Cornell University in 1991 with a dissertation on the archaeological publications of Giovanni Battista Piranesi. She studies the history of pre,scientific archaeology, from Pirro Ligorio to Piranesi, with a particular focus on illustration as a means to convey historical knowledge. She has published on this subject in a variety of venues, and is beginning a book,length manuscript on the subject. In 1995,96, she was awarded a J. Paul Getty post,doctoral fellowship to study the Accademia degli Arcadi, a society founded in 1690 primarily to restore good taste in literature, and its successes and failures in bringing about the reform of Italian society and architecture. She has written a book entitled The Bosco Parrasio: Performance and Perfectibility in the Garden of the Arcadians, which focuses on their garden meeting place as a breeding ground for a utopian society. Dr Dixon teaches art history at the University of Tulsa in Oklahoma. Giovanni Battista Piranesi (1720,1778) developed a way of representing the archaeological past by using the multi,informational image, an engraved illustration which appears to be a composite of various drawings, on various surfaces, and employing various modes of representation, scale and detail. The cartographic tradition, particularly maps from sixteenth,century Europe, offer a precedent for this type of illustration. Piranesi found theoretical underpinnings for it in contemporary discussions about the workings of the human memory, which was identified as a viable tool for those pursuing historical knowledge. His illustrations make visible the processes of memory on an assemblage of archaeological information, and they were a means to historical reconstruction. Archaeologists of the generation after Piranesi did not use the multi,informational image as the science of archaeology underwent a sea change at the end of the century. However, some compilers of travel literature, in particular Jean,Laurent,Pierre HoÃ,el, author and illustrator of Voyage pittoresque des isles de Sicile, de Malte, et de Lipari, found the format suitable to their purposes. Like Piranesi's, Hoüel's multi,informational images reveal the hand of the artist on the information he had diligently collected and ordered; Hoüel's picturesque illustrations of the southern Italian islands' people and places are self,consciously subjective. The format also makes apparent what was so appealing to many a voyager ,the apparent survival of the past in the culture of the present. [source] Evaluation of the antimicrobial activity of cationic polyethylenimines on dry surfacesBIOTECHNOLOGY PROGRESS, Issue 5 2008Stephen A. Koplin Abstract The antimicrobial activity of cationic N -dodecyl- N -methylpolyethylenimine (PEI+) against S. aureus, A. baumannii, and E. coli was evaluated when the polymer was applied as a coating to various surfaces using a paint-like procedure. Antimicrobial activity of PEI+ as a function of time was determined using an assay for long-term survival involving placement of single drops of various bacterial concentrations on dry surfaces. These data were compared with an assay method where bacteria were applied by spraying and surfaces were incubated overnight under agar. PEI+-coated surfaces were found to be highly bactericidal after 30 min when bacteria were sprayed onto surfaces. However, when bacteria were applied as single drops, PEI+-coated surfaces were less biocidal at short contact times particularly for A. baumannii and E. coli. The observations are explained in the context of the difference in drying time between drops deposited on uncoated surfaces and PEI+-coated surfaces and the sensitivity of bacterial survival to dehydration. These results demonstrate that PEI+-coated surfaces are not effectively biocidal for some types of bacteria under certain conditions and that the method of assaying bactericidal efficiency can greatly affect the results obtained. [source] Analytical Expressions for Quantitative Scanning Electrochemical Microscopy (SECM)CHEMPHYSCHEM, Issue 3 2010Christine Lefrou Dr. Abstract Scanning electrochemical microscopy (SECM), is a recent analytical technique in electrochemistry, which was developed in the 1990s and uses microelectrodes to probe various surfaces. Even with the well-known disc microelectrodes, the system geometry is not as simple as in regular electrochemistry. As a consequence even the simplest experiments, the so-called positive and negative feedback approach curves, cannot be described with exact analytical expressions. This review gathers all the analytical expressions available in the SECM literature in steady-state feedback experiments. Some of them are claimed as general expressions, other are presented as approximate. Their validity is discussed in the light of the current understanding and computer facilities. [source] | |||||||||||||