XPS identification of bulk hole defects and itinerant Fe 3d electrons in natural troilite (FeS)     

William M Skinner  H.Wayne Nesbitt 《Geochimica et cosmochimica acta》2004,68(10):2259-2263

XPS measurements have been made of vacuum-fractured monoclinic pyrrhotite and troilite that highlight sulfur coordination (S 2p) and iron electronic state (Fe 2p) differences between these two minerals as a result of iron lattice site occupancy. Metal-like Fe states are observed in the Fe 2p spectrum of troilite due to increased occupancy of Fe lattice sites and increased Fe-Fe 3d orbital interaction within the constraints of the mineral structure. Additional electron population near the top of the troilite valence band is confirmed by XPS measurement. These results provide comprehensive experimental evidence for itinerent 3d electrons in the natural iron sulfides.  相似文献   

Subsidence breccias in kimberlite pipes—an application of fractal analysis     

Wayne Barnett   《Lithos》2004,76(1-4):299-316

A particular variety of volcanogenic country rock breccia is described; a contact breccia that has been identified at Venetia, River Ranch and Wimbledon kimberlite pipes. The contact breccia is clast supported with no juvenile kimberlite component, has tightly packed, angular fragments (with occasional rounding of smaller particles), and has a shear-fabric dipping towards the center of each kimberlite pipe or volcanic event. Clasts have preferred orientations parallel to the fabric. Photographs of the breccia in the open pit face and measured data from drill core are analyzed specifically to quantify the clast size distributions and clast shapes by means of fractal analysis. The fractal dimension is one means of characterizing the breccia because the dimension can be specific to a fragmentation mechanism. Clast size distribution fractal dimensions in the coarser particles (greater than circa 3 cm) range from greater than 3 for nonsheared breccia, down to circa 2.3 for the sheared breccia. Breccia characterization based on this fractal analysis suggests that fragmentation occurred initially from confined high-energy explosions, followed by collapse and abrasion by subsequently gravity-induced rockmass subsidence. All studied contact breccias produced a distinctive fractal signature in the finer particles (<3 cm) of circa 1.6 that can be explained by a comminution fragmentation process in that particular particle size range. It is suggested that these subsidence breccias require a substantial volume deficit at depth within the volcanic pipe in order to explain their origin and size. The methodology used in this study could be used to characterize any other volcanic breccia and further model their origins.  相似文献   

Comparison of llama fiber obtained from two production regions of Argentina     

Wayne Coates  Ricardo Ayerza 《Journal of Arid Environments》2004,58(4):344

The Puna is an arid region running along the Andes mountains, more than 3600 m above sea level. Overgrazing has severely degraded much of this ecosystem, and this has dramatically reduced agricultural production and resulted in poverty for human inhabitants. Llamas are native to the Puna and are well suited to live there. Their grazing habits and digestive system make efficient use of native forages, and their padded feet keep soil disturbance to a minimum, thereby reducing erosion. Uncontrolled llama breeding over the last 500 years has degraded the quality of the fiber they produce, so today it is generally of low quality. Analysis of llama fibers obtained from two production regions of Argentina showed that some llamas possess sufficiently fine mean fiber diameters (less than 23 μm if guard hairs are excluded) to allow their fleeces to be sold at a premium. A higher price would make llamas more attractive to raise than the goats and sheep commonly found in the Puna today. Switching to llama production would increase grower income and sustainability of agriculture in the region.  相似文献   

Iteration method to determine the eigenvalues and eigenvectors of a target multiplet including full mode coupling   总被引：2，自引：0，他引：2  

Arwen Deuss  John Woodhouse 《Geophysical Journal International》2004,159(1):326-332

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The role of moisture cycling in the weathering of a quartz chlorite schist in a tropical environment: findings of a laboratory simulation   总被引：1，自引：0，他引：1  

Tony Wells  Philip Binning  Garry Willgoose 《地球表面变化过程与地形》2005,30(4):413-428

Long‐term weathering of a quartz chlorite schist via wetting and drying was studied under a simulated tropical climate. Cubic rock samples (15 mm × 15 mm × 15 mm) were cut from larger rocks and subjected to time‐compressed climatic conditions simulating the tropical wet season climate at the Ranger Uranium Mine in the Northern Territory, Australia. Fragmentation, moisture content and moisture uptake rate were monitored over 5000 cycles of wetting and drying. To determine the impact of climatic variables, five climatic regimes were simulated, varying water application, temperature and drying. One of the climatic regimes reproduced observed temperature and moisture variability at the Ranger Uranium Mine, but over a compressed time scale. It is shown that wetting and drying is capable of weathering quartz chlorite schist with changes expected over a real time period of decades. While wetting and drying alone does produce changes to rock morphology, the incorporation of temperature variation further enhances weathering rates. Although little fragmentation occurred in experiments, significant changes to internal pore structure were observed, which could potentially enhance other weathering mechanisms. Moisture variability is shown to lead to higher weathering rates than are observed when samples are subjected only to leaching. Finally, experiments were conducted on two rock samples from the same source having only subtle differences in mineralogy. The samples exhibited quite different weathering rates leading to the conclusion that our knowledge of the role of rock type and composition in weathering is insufficient for the accurate determination of weathering rates. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Uncertainty analysis of a model of wind-blown volcanic plumes     

Mark J. Woodhouse  Andrew J. Hogg  Jeremy C. Phillips  Jonathan C. Rougier 《Bulletin of Volcanology》2015,77(10):1-28

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Mapping and monitoring carbon stocks with satellite observations: a comparison of methods     

Scott J Goetz  Alessandro Baccini  Nadine T Laporte  Tracy Johns  Wayne Walker  Josef Kellndorfer  Richard A Houghton  Mindy Sun 《Carbon balance and management》2009,4(1):2-7

Mapping and monitoring carbon stocks in forested regions of the world, particularly the tropics, has attracted a great deal of attention in recent years as deforestation and forest degradation account for up to 30% of anthropogenic carbon emissions, and are now included in climate change negotiations. We review the potential for satellites to measure carbon stocks, specifically aboveground biomass (AGB), and provide an overview of a range of approaches that have been developed and used to map AGB across a diverse set of conditions and geographic areas. We provide a summary of types of remote sensing measurements relevant to mapping AGB, and assess the relative merits and limitations of each. We then provide an overview of traditional techniques of mapping AGB based on ascribing field measurements to vegetation or land cover type classes, and describe the merits and limitations of those relative to recent data mining algorithms used in the context of an approach based on direct utilization of remote sensing measurements, whether optical or lidar reflectance, or radar backscatter. We conclude that while satellite remote sensing has often been discounted as inadequate for the task, attempts to map AGB without satellite imagery are insufficient. Moreover, the direct remote sensing approach provided more coherent maps of AGB relative to traditional approaches. We demonstrate this with a case study focused on continental Africa and discuss the work in the context of reducing uncertainty for carbon monitoring and markets.  相似文献   

Isolation of protein from Chlorella sorokiniana CY1 using liquid biphasic flotation assisted with sonication through sugaring-out effect     

Chia  Shir Reen  Chew  Kit Wayne  Show  Pau Loke  Sivakumar  Manickam  Ling  Tau Chuan  Tao  Yang 《中国海洋湖沼学报》2019,37(3):898-908

Microalgae, a sustainable source of multi beneficial components has been discovered and could be utilised in pharmaceutical, bioenergy and food applications. This study aims to investigate the sugaring-out effect on the recovery of protein from wet green microalga, Chlorella sorokiniana CY1 which was assisted with sonication. A comparison of monosaccharides and disaccharides as one of the phaseforming constituents shows that the monosaccharides, glucose was the most suitable sugar in forming the phases with acetonitrile to enhance the production of protein(52% of protein). The protein productivity of microalgae was found to be significantly influenced by the volume ratio of both phases, as the yield of protein increased to 77%. The interval time between the sonication as well as the sonication modes were influencing the protein productivity as well. The optimum protein productivity was obtained with 10 s of resting time in between sonication. Pulse mode of sonication was suitable to break down the cell wall of microalgae compared to continuous mode as a lower protein yield was obtained with the application of continuous mode. The optimum condition for protein extraction were found as followed: 200 g/L glucose as bottom phase with volume ratio of I:1.25, 10 s of resting time for ultrasonication, 5 s of ultrasonication in pulse mode and 0.25 g of biomass weight. The high yield of protein about 81% could be obtained from microalgae which demonstrates the potential of this source and expected to play an important role in the future.  相似文献   

Isolation of protein from Chlorella sorokiniana CY1 using liquid biphasic flotation assisted with sonication through sugaring-out effect     

CHIA Shir Reen  CHEW Kit Wayne  SHOW Pau Loke  SIVAKUMAR Manickam  LING Tau Chuan  TAO Yang 《海洋湖沼学报（英文）》2019,(3):898-908

Microalgae,a sustainable source of multi beneficial components has been discovered and could be utilised in pharmaceutical,bioenergy and food applications.This study aims to investigate the sugaring-out effect on the recovery of protein from wet green microalga,Chlorella sorokiniana CY1 which was assisted with sonication.A comparison of monosaccharides and disaccharides as one of the phaseforming constituents shows that the monosaccharides,glucose was the most suitable sugar in forming the phases with acetonitrile to enhance the production of protein(52% of protein).The protein productivity of microalgae was found to be significantly influenced by the volume ratio of both phases,as the yield of protein increased to 77%.The interval time between the sonication as well as the sonication modes were influencing the protein productivity as well.The optimum protein productivity was obtained with 10s of resting time in between sonication.Pulse mode of sonication was suitable to break down the cell wall of microalgae compared to continuous mode as a lower protein yield was obtained with the application of continuous mode.The optimum condition for protein extraction were found as followed:200g/L glucose as bottom phase with volume ratio of 1:1.25,10s of resting time for ultrasonication,5s of ultrasonication in pulse mode and 0.25g of biomass weight.The high yield of protein about 81% could be obtained from microalgae which demonstrates the potential of this source and expected to play an important role in the future.  相似文献   

Archaeological geology of the Rustad Quarry site (32RI775): An early archaic site in Southeastern North Dakota     

Garry Leonard Running 《Geoarchaeology》1995,10(3):183-204

At The Rustad Quarry Site (32RI775), in southeastern North Dakota, Early Archaic artifacts, bison bone, and hearth features were found in the lowest of three Boroll-like buried soils formed in alluvial fan sediments. Alluvial fan sediments were deposited from 8000 to 4925 B.P., and were then buried by eolian sand. The alluvial fan sediments (mudflows) bury lacustrine sediments (Sherack Formation deposited from 9900 to 9500 B.P. in Glacial Lake Agassiz II), both of which overlie a Moorhead Phase fluvial terrace deposited from 10,900 to 9,900 B.P. Cultural remains were associated with five radiocarbon ages, three on archaeological charcoal (7180 B.P., 7240 B.P., and 7550 B.P.) and two on organic carbon from two welded A-horizons containing the cultural remains (7370 B.P. and 7675 B.P.). A well-developed Aquoll-like soil formed in the lacustrine sediments from 9500 to 8000 B.P. Soil morphology and chemistry of the Boroll-like fan soils, the Aquoll-like lacustrine soil, and other Boroll-like soils formed in eolian and deltaic sediments nearby suggest a subhumid, cool continental climate with riparian woodland and mixed prairie vegetation at the site and surrounding area from 11,400 B.P. to the present. This partially contradicts paleoenvironmental reconstruction from pollen sites nearby that suggest the area was covered by a closed canopy spruce forest from terminal late-Pleistocene to 10,000 B.P. Alluvial fan formation and eolian activity on the adjacent Sheyenne Delta occurred from 8000 to 5000 B.P., which indicates greater landscape instability and drier conditions during the mid-Holocene (Altithermal).  相似文献