Quartz grain microtextures of sediments from ODP Hole 188-1166A (Table 1)

This paper presents the results of the scanning electron microscopic (SEM) analysis of quartz grains from a selection of samples at Site 1166. Ocean Drilling Program Leg 188 drilled Site 1166 on the Prydz Bay continental shelf, Antarctica, to document onset and fluctuations of East-Antarctic glaciation. This site recovered Upper Pliocene-Holocene glacial sediments directly above Cretaceous through Lower Oligocene sediments recording the transition from preglacial to early glacial conditions. SEM analysis of quartz grains at Site 1166 was used to characterize the glacial and preglacial sediments by their diagnostic textures. Angular edges, edge abrasion as well as arcuate to straight steps, are the most frequent features in glacial deposits. The highest frequency of grains with round edges is present in Middle-Late Eocene fluvio-deltaic sands. However, angular outlines, fractured plates with subparallel linear fractures and edge abrasion indicating glacier influence are also present. Preglacial carbonaceous mudstone and laminated gray claystone show distinctive high relief quartz grains and some chemical weathering on grain surfaces. The results of the microtextural analysis of quartz grains are used to verify some critical periods of ice sheet evolution, such as the transition from the East Antarctic preglacial to glacial conditions on the continental shelf from Middle/Late Eocene to Late Eocene/Early Oligocene time.

Occurrence of microtextures recorded from quartz sand grains of ODP Hole 178-1101A (Table 1)

Sediment drifts on the continental rise are located proximal to the western side of the Antarctic Peninsula and recorded changes in glacial volume and thermal regime over the last ca. 15 m.y. At Ocean Drilling Program (ODP) Site 1101 (Leg 178), which recovered sediments back to 3.1 Ma, glacial-interglacial cyclicity was identified based on the biogenic component and sedimentary structures observed in X-radiographs, magnetic susceptibility and lithofacies descriptions. Glacial intervals are dominated by fine-grained laminated mud and interglacial units consist of bioturbated muds enriched in biogenic components. From 2.2 to 0.76 Ma, planktonic foraminifera and calcareous nannofossils dominate in the interglacials suggesting a shift of the Antarctic Polar Front (APF) to the south near the drifts. Prior to 2.2 Ma, cyclicity cannot be identified and diatoms dominate the biogenic component and high percent opal suggests warmer conditions south of the APF and reduced sea ice over the drifts. Analyses of the coarse-grained terrigenous fraction (pebbles and coarse sand) from Sites 1096 and 1101 record glaciers at sea-level releasing iceberg-rafted debris (IRD) throughout the last 3.1 m.y. Analyses of quartz sand grains in IRD with the scanning electron microscope (SEM) show an abrupt change in the frequency of occurrence of microtextures at ~1.35 Ma. During the Late Pliocene to Early Pleistocene, the population of quartz grains included completely weathered grains and a low frequency of crushing and abrasion, suggesting that glaciers were small and did not inundate the topography. Debris shed from mountain peaks was transported supraglacially or englacially allowing weathered grains to pass through the glacier unmodified. During glacial periods from 1.35-0.76 Ma, glaciers expanded in size. The IRD flux was very high and dropstones have diverse lithologies. Conditions resembling those at the Last Glacial Maximum (LGM) have been episodically present on the Antarctic Peninsula since ~0.76 Ma. Quartz sand grains show high relief, fracture and abrasion common under thick ice and the IRD flux is low with a more restricted range of dropstone lithologies.

Electrical and dielectric properties of uncoated and coated wood-free paper for electrophotography

The print substrate influences the print result in dry toner electrophotography, which is a widely used digital printing method. The influence of the substrate can be seen more easily in color printing, as that is a more complex process compared to monochrome printing. However, the print quality is also affected by the print substrate in grayscale printing. It is thus in the interests of both substrate producers and printing equipment manufacturers to understand the substrate properties that influence the quality of printed images in more detail. In dry toner electrophotography, the image is printed by transferring charged toner particles to the print substrate in the toner transfer nip, utilizing an electric field, in addition to the forces linked to the contact between toner particles and substrate in the nip. The toner transfer and the resulting image quality are thus influenced by the surface texture and the electrical and dielectric properties of the print substrate. In the investigation of the electrical and dielectric properties of the papers and the effects of substrate roughness, in addition to commercial papers, controlled sample sets were made on pilot paper machines and coating machines to exclude uncontrolled variables from the experiments. The electrical and dielectric properties of the papers investigated were electrical resistivity and conductivity, charge acceptance, charge decay, and the dielectric permittivity and losses at different frequencies, including the effect of temperature. The objective was to gain an understanding of how the electrical and dielectric properties are affected by normal variables in papermaking, including basis weight, material density, filler content, ion and moisture contents, and coating. In addition, the dependency of substrate resistivity on the electric field applied was investigated. Local discharging did not inhibit transfer with the paper roughness levels that are normal in electrophotographic color printing. The potential decay of paper revealed that the charge decay cannot be accurately described with a single exponential function, since in charge decay there are overlapping mechanisms of conduction and depolarization of paper. The resistivity of the paper depends on the NaCl content and exponentially on moisture content although it is also strongly dependent on the electric field applied. This dependency is influenced by the thickness, density, and filler contents of the paper. Furthermore, the Poole-Frenkel model can be applied to the resistivity of uncoated paper. The real part of the dielectric constant ε’ increases with NaCl content and relative humidity, but when these materials cannot polarize freely, the increase cannot be explained by summing the effects of their dielectric constants. Dependencies between the dielectric constant and dielectric loss factor and NaCl content, temperature, and frequency show that in the presence of a sufficient amount of moisture and NaCl, new structures with a relaxation time of the order of 10-3 s are formed in paper. The ε’ of coated papers is influenced by the addition of pigments and other coating additives with polarizable groups and due to the increase in density. The charging potential decreases and the electrical conductivity, potential decay rate, and dielectric constant of paper increase with increasing temperature. The dependencies are exponential and the temperature dependencies and their activation energies are altered by the ion content. The results have been utilized in manufacturing substrates for electrophotographic color printing.

Activated Carbons Impregnated with Na2S and H2SO4: Texture, Surface Chemistry and Application to Mercury Removal from Aqueous Solutions

The effects of treatment of an activated carbon with Sulphur precursors on its textural properties and on the ability of the complex synthesized for mercury removal in aqueous solutions are studied. To this end, a commercial activated carbon has been modified by treatments with aqueous solutions of Na2S and H2SO4 at two temperatures (25 and 140 °C) to introduce sulphur species on its surface. The prepared adsorbents have been characterized by N2 (-196 °C) and CO2 (0 °C) adsorption, thermogravimetric analysis, temperature-programmed decomposition and X-ray photoelectron spectroscopy, and their adsorption capacities to remove Hg(II) ions in aqueous solutions have been determined. It has been shown that the impregnation treatments slightly modified the textural properties of the samples, with a small increase in the textural parameters (BET surface area and mesopore volumes). By contrast, surface oxygen content was increased when impregnation was carried out with Na2S, but it decreased when H2SO4 was used. However, the main effect of the impregnation treatments was the formation of surface sulphur complexes of thiol type, which was only achieved when the impregnation treatments were carried out at low temperature (25 °C). The presence of surface sulphur enhances the adsorption behaviour of these samples in the removal of Hg(II) cations in aqueous solutions at pH 2. In fact, complete Hg(II) removal is only obtained with the sulphur-containing activated carbons.

Desiccant capability of organic xerogels: Surface chemistry vs porous texture

Resorcinol-Formaldehyde xerogels are organic polymers that can be easily tailored to have specific properties. These materials are composed of carbon, hydrogen and oxygen, and have a surface that is very rich in oxygen functionalities, and is therefore very hydrophilic. Their most interesting feature is that they may have the same chemical composition but a different porous texture. Consequently, the influence of porous characteristics, such as pore volume, surface area or pore size can be easily assessed. In this work, a commonly used desiccant, silica gel, is compared with organic xerogels to determine their rate and capacity of water adsorption, and to evaluate the role of surface chemistry versus porous texture. It was found that organic xerogels showed a higher rate of moisture adsorption than silica gel. Pore structure also seems to play an important role in water adsorption capacity. The OX-10 sample, whose porosity was mainly composed of micro-mesoporosity displayed a water adsorption capacity two times greater than that of the silica gel, and three times higher than that of the totally macroporous xerogel OX-2100. The presence of feeder pores (mesopores) that facilitate the access to the hydrophilic surface was observed to be the key factor for a good desiccant behaviour. Neither the total pore volume nor the high surface area (i.e. high microporosity) of the desiccant sample, is as important as the mesopore structure.

Application of edge-to-edge matching model to understand the in-plane texture of TiSi2 (C49) thin films on (001)(Si) surface

The edge-to-edge matching model, which was originally developed for predicting crystallographic features in diffusional phase transformations in solids, has been used to understand the formation of in-plane textures in TiSi2 (C49) thin films on Si single crystal (001)si surface. The model predicts all the four previously reported orientation relationships between C49 and Si substrate based on the actual atom matching across the interface and the basic crystallographic data only. The model has strong potential to be used to develop new thin film materials. (c) 2006 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

The interaction of luminance and texture amplitude in surface depth perception

Previous studies have suggested separate channels for detection of first-order luminance modulations (LM) and second-order modulations of the local amplitude (AM) of a texture. Mixtures of LM and AM with different phase relationships appear very different: in-phase compounds (LM + AM) look like 3-D corrugated surfaces, while out-of-phase compounds (LM - AM) appear flat and/or transparent. This difference may arise because the in-phase compounds are consistent with multiplicative shading, while the out-of-phase compounds are not. We investigated the role of these modulation components in surface depth perception. We used a textured background with thin bars formed by local changes in luminance and/or texture amplitude. These stimuli appear as embossed surfaces with wide and narrow regions. Keeping the AM modulation depth fixed at a suprathreshold level, we determined the amount of luminance contrast required for observers to correctly indicate the width (narrow or wide) of 'raised' regions in the display. Performance (compared to the LM-only case) was facilitated by the presence of AM, but, unexpectedly, performance for LM - AM was as good as for LM + AM. Thus, these results suggest that there is an interaction between first-order and second-order mechanisms during depth perception based on shading cues, but the phase dependence is not yet understood.

Optimization of the Enzymatic Interesterification of Milk Fat and Canola Oil Blends Using Immobilized Rhizopus oryzae Lipase by Response Surface Methodology

Blends of milk fat and canola oil (MF:CNO) were enzymatically interesterified (EIE) by Rhizopus oryzne lipase immobilized on polysiloxane-polyvinyl alcohol (SiO(2)-PVA) composite, in a solvent-free system. A central composite design (CCD) was used to optimize the reaction, considering the effects of different mass fractions of binary blends of MF:CNO (50:50, 65:35 and 80:20) and temperatures (45, 55 and 65 degrees C) on the composition and texture properties of the interesterified products, taking the interesterification degree (ID) and consistency (at 10 degrees C) as response variables. For the ID variable both mass fraction of milk fat in the blend and temperature were found to be significant, while for the consistency only mass fraction of milk fat was significant. Empiric models for ID and consistency were obtained that allowed establishing the best interesterification conditions: blend with 65 % of milk fat and 35 %, of canola oil, and temperature of 45 degrees C. Under these conditions, the ID was 19.77 %) and the consistency at 10 degrees C was 56 290 Pa. The potential of this eco-friendly process demonstrated that a product could be obtained with the desirable milk fat flavour and better spreadability under refrigerated conditions.

Infiltration from surface and buried point sources: The average wetting water content

The assumption in analytical solutions for flow from surface and buried point sources of an average water content, (θ) over bar, behind the wetting front is examined. Some recent work has shown that this assumption fitted some field data well. Here we calculated (θ) over bar using a steady state solution based on the work by Raats [1971] and an exponential dependence of the diffusivity upon the water content. This is compared with a constant value of (θ) over bar calculated from an assumption of a hydraulic conductivity at the wetting front of 1 mm day(-1) and the water content at saturation. This comparison was made for a wide range of soils. The constant (θ) over bar generally underestimated (θ) over bar at small wetted radii and overestimated (θ) over bar at large radii. The crossover point between under and overestimation changed with both soil properties and flow rate. The largest variance occurred for coarser texture soils at low-flow rates. At high-flow rates in finer-textured soils the use of a constant (θ) over bar results in underestimation of the time for the wetting front to reach a particular radius. The value of (θ) over bar is related to the time at which the wetting front reaches a given radius. In coarse-textured soils the use of a constant value of (θ) over bar can result in an error of the time when the wetting front reaches a particular radius, as large as 80% at low-flow rates and large radii.

On-line analysis of froth surface in coal and mineral flotation using JKFrothCam

The personal computer revolution has resulted in the widespread availability of low-cost image analysis hardware. At the same time, new graphic file formats have made it possible to handle and display images at resolutions beyond the capability of the human eye. Consequently, there has been a significant research effort in recent years aimed at making use of these hardware and software technologies for flotation plant monitoring. Computer-based vision technology is now moving out of the research laboratory and into the plant to become a useful means of monitoring and controlling flotation performance at the cell level. This paper discusses the metallurgical parameters that influence surface froth appearance and examines the progress that has been made in image analysis of flotation froths. The texture spectrum and pixel tracing techniques developed at the Julius Kruttschnitt Mineral Research Centre are described in detail. The commercial implementation, JKFrothCam, is one of a number of froth image analysis systems now reaching maturity. In plants where it is installed, JKFrothCam has shown a number of performance benefits. Flotation runs more consistently, meeting product specifications while maintaining high recoveries. The system has also shown secondary benefits in that reagent costs have been significantly reduced as a result of improved flotation control. (C) 2002 Elsevier Science B.V. All rights reserved.

Strategic Plan for Improved Concrete Pavement Surface Characteristics, July 2006

Surface characteristics represent a critical issue facing pavement owners and the concrete paving industry. The traveling public has come to expect smoother, quieter, and better drained pavements, all without compromising safety. The overall surface characteristics issues is extremely complex since all pavement surface characteristics properties, including texture, noise, friction, splash/spray, rolling resistance, reflectivity/illuminance, and smoothness, are complexly related. The following needs and gaps related to achieving desired pavement surface characteristics need to be addressed: determined how changes in one surface characteristic affect, either beneficially or detrimentally, other characteristics of the pavement, determine the long-term surface and acoustic durability of different textures, and develop, evaluate, and standardize new data collection and analysis tools. It is clear that an overall strategic and coordinated research approach to the problem must be developed and pursued to address these needs and gaps.

SOIL PHOSPHORUS THRESHOLDS IN EVALUATING RISK OF ENVIRONMENTAL TRANSFER TO SURFACE WATERS IN SANTA CATARINA, BRAZIL

The State of Santa Catarina, Brazil, has agricultural and livestock activities, such as pig farming, that are responsible for adding large amounts of phosphorus (P) to soils. However, a method is required to evaluate the environmental risk of these high soil P levels. One possible method for evaluating the environmental risk of P fertilization, whether organic or mineral, is to establish threshold levels of soil available P, measured by Mehlich-1 extractions, below which there is not a high risk of P transfer from the soil to surface waters. However, the Mehlich-1 extractant is sensitive to soil clay content, and that factor should be considered when establishing such P-thresholds. The objective of this study was to determine P-thresholds using the Mehlich-1 extractant for soils with different clay contents in the State of Santa Catarina, Brazil. Soil from the B-horizon of an Oxisol with 800 g kg-1 clay was mixed with different amounts of sand to prepare artificial soils with 200, 400, 600, and 800 g kg-1 clay. The artificial soils were incubated for 30 days with moisture content at 80 % of field capacity to stabilize their physicochemical properties, followed by additional incubation for 30 days after liming to raise the pH(H2O) to 6.0. Soil P sorption curves were produced, and the maximum sorption (Pmax) was determined using the Langmuir model for each soil texture evaluated. Based on the Pmax values, seven rates of P were added to four replicates of each soil, and incubated for 20 days more. Following incubation, available P contents (P-Mehlich-1) and P dissolved in the soil solution (P-water) were determined. A change-point value (the P-Mehlich-1 value above which P-water starts increasing sharply) was calculated through the use of segmented equations. The maximum level of P that a soil might safely adsorb (P-threshold) was defined as 80 % of the change-point value to maintain a margin for environmental safety. The P-threshold value, in mg dm-3, was dependent on the soil clay content according to the model P-threshold = 40 + Clay, where the soil clay content is expressed as a percentage. The model was tested in 82 diverse soil samples from the State of Santa Catarina and was able to distinguish samples with high and low environmental risk.

Surface-enhanced laser desorption/ionisation time-of-flight mass spectrometry: A tool to predict pork quality

Expression of water soluble proteins of fresh pork Longissimus thoracis from 4 pure breed pigs (Duroc, Large White, Landrace, and Piétrain) was studied to identify candidate protein markers for meat quality. Surface-enhanced laser desorption/ionisation time-of-flight mass spectrometry (SELDI-TOF-MS) was used to obtain the soluble protein profiles of Longissimus thoracis muscles. The pure breeds showed differences among the studied meat quality traits (pHu, drip loss, androstenone, marbling, intramuscular fat, texture, and moisture), but no significant differences were detected in sensory analysis. Associations between protein peaks obtained with SELDI-TOF-MS and meat quality traits, mainly water holding capacity, texture and skatole were observed. Of these peaks, a total of 10 peaks from CM10 array and 6 peaks from Q10 array were candidate soluble protein markers for pork loin quality. The developed models explained a limited proportion of the variability, however they point out interesting relationships between protein expression and meat quality