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Articles 961 - 990 of 2524

Full-Text Articles in Physical Sciences and Mathematics

Piezoelectric Effects In Cholesteric Elastomer Gels, C. C. Chang, Liang-Chy Chien, R. Meyer Oct 2013

Piezoelectric Effects In Cholesteric Elastomer Gels, C. C. Chang, Liang-Chy Chien, R. Meyer

Liang-Chy Chien

We report a piezolectric effect in cholesteric liquid crystalline elastomer gels. When we apply a shear stress to a cholesteric elastomer gel in the direction perpendicular to its helical axis, a polarization can be induced in the direction perpendicular to both the stress and the helix. This experimental observation agrees with the theory proposed by Pelcovits and Meyer [J. Phys. II France 5, 877 (1995)].

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Formation And Localization Of Internal Polymer Columnar Structures In Liquid Crystal Cells, Qingbing Wang, Liang-Chy Chien, Satyendra Kumar Oct 2013

Formation And Localization Of Internal Polymer Columnar Structures In Liquid Crystal Cells, Qingbing Wang, Liang-Chy Chien, Satyendra Kumar

Liang-Chy Chien

Internal polymer columnar structures in liquid crystal (LC) cells have been produced using the method of thermally-induced phase separation of LC/prepolymer solution and solidified by photopolymerization. These polymer columns adhere to both substrates and enhance control of the LC cell spacing and mechanical stability. The existence and profile of the polymer columns were investigated by optical and scanning electron microscopy techniques. Supertwisted nematic LC cells with polymer columnar structures have been constructed using this method and their electro-optical characteristics measured.

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Double Twist In Helical Polymer "Soft" Crystals, Christopher Li, Stephen Cheng, Jason Ge, Feng Bai, John Zhang, Ian Mann, Frank Harris, Liang-Chy Chien, Donghang Yan, Tianbai He, Bernard Lotz Oct 2013

Double Twist In Helical Polymer "Soft" Crystals, Christopher Li, Stephen Cheng, Jason Ge, Feng Bai, John Zhang, Ian Mann, Frank Harris, Liang-Chy Chien, Donghang Yan, Tianbai He, Bernard Lotz

Liang-Chy Chien

In natural and synthetic materials having non-racemic chiral centers, chirality and structural ordering each play a distinct role in the formation of ordered states. Configurational chirality can be extended to morphological chirality when the phase, structures possess low liquid crystalline order. In the crystalline states the crystallization process suppresses the chiral helical morphology due to strong ordering interactions, In this Letter, we report the first observation of helical single lamellar crystals of synthetic non-racemic chiral polymers. Experimental evidence shows that the molecular chains twist along both the long and short axes of the helical lamellar crystals, which is the first …

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Liquid-Crystal Photoalignment Using Low-Molecular-Weight Photo-Cross-Linkable Composites, O. Yaroshchuk, L Cada, M. Sonpatki, Liang-Chy Chien Oct 2013

Liquid-Crystal Photoalignment Using Low-Molecular-Weight Photo-Cross-Linkable Composites, O. Yaroshchuk, L Cada, M. Sonpatki, Liang-Chy Chien

Liang-Chy Chien

A liquid-crystal (LC) photoalignment method, based on the use of low-molecular-weight photo-cross-linkable (LMWPC) composites is proposed. The basic idea of this method is that cross linking or both cross linking and polymerization of LMWPC composites are realized immediately on the substrate simultaneously with the photoalignment or as a stage of the backing process. Providing the advantages of a conventional photoalignment method, the use of LMWPC composites simplifies the synthesis and alignment procedure, makes possible wide range control of pretilt angles, and enhances the thermal stability of the LC alignment. The abilities of this method are demonstrated using a series of …

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Cholesteric Liquid-Crystal Polymer Dispersion For Haze-Free Light Shutters, Deng-Ke Yang, Liang-Chy Chien, J. Donae Oct 2013

Cholesteric Liquid-Crystal Polymer Dispersion For Haze-Free Light Shutters, Deng-Ke Yang, Liang-Chy Chien, J. Donae

Liang-Chy Chien

A new dispersion involving a polymer in low concentration with a cholesteric liquid crystal is reported. Two types of light modulators from these materials are described as a normal mode shutter which is opaque (light scattering) in the field-OFF state and transparent in the field-ON state and a reverse-mode shutter with the opposite field conditions. The transparent state of both cells is haze-free for all viewing angles making the material attractive for window applications and direct view displays.

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Effect Of A Polymer Network On The Alignment And The Rotational Viscosity Of A Nematic Liquid-Crystal, Antal Jákli, D. Kim, Liang-Chy Chien, A. Saupe Oct 2013

Effect Of A Polymer Network On The Alignment And The Rotational Viscosity Of A Nematic Liquid-Crystal, Antal Jákli, D. Kim, Liang-Chy Chien, A. Saupe

Liang-Chy Chien

Polymer dispersions were made by photoinduced polymerization of 4,4'-bisacryloyl-biphenyl in liquid crystal 4-4'-cyano pentyl biphenyl as nematic solvent. Samples were prepared with 0.5, 1, and 1.5 wt % monomer. The polymerization was done in the isotropic phase. The rotational viscosities of the two lower concentration samples increased only moderately after UV curing (3 mW/cm2, 25 min). The 1.5 wt % sample gave under the same condition a nematic with a fairly rigid anisotropic network that did not realign in magnetic field up to 20 kG. We estimate that the mesh size of the network was in the order of 1 …

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An Assessment Of Space Environmental Conditions During The Recent Anik E1 Spacecraft Operational Failure, D Baker, J Allen, R Belian, J Blake, S Kanekal, B Klecker, R Lepping, X Li, R Mewaldt, K Ogilvie, T Onsager, G Reeves, G Rostoker, R Sheldon, H Singer, H Spence, Niescja Turner Oct 2013

An Assessment Of Space Environmental Conditions During The Recent Anik E1 Spacecraft Operational Failure, D Baker, J Allen, R Belian, J Blake, S Kanekal, B Klecker, R Lepping, X Li, R Mewaldt, K Ogilvie, T Onsager, G Reeves, G Rostoker, R Sheldon, H Singer, H Spence, Niescja Turner

Niescja E. Turner

A serious operational failure occurred onboard the Anik E1 spacecraft at geostationary orbit on 26 March 1996 at 2047 UT. The satellite lost half of its solar power panels, thereby causing a reduction by about two-thirds of its communication throughput capacity. In this report we discuss other known operational problems of spacecraft at, or near, geostationary orbit at about the same time as the Anik problem. We also show data from the CANOPUS ground-based array as well as solar, solar wind, and magnetospheric satellites in order to assess environmental conditions that might have played a role in the identified anomalies. …

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Sample Pre-Treatment And The Determination Of Some Chemical Properties Of Acid Sulfate Soil Materials, Crystal Maher, Leigh Sullivan, Nicholas Ward Oct 2013

Sample Pre-Treatment And The Determination Of Some Chemical Properties Of Acid Sulfate Soil Materials, Crystal Maher, Leigh Sullivan, Nicholas Ward

Dr Nicholas J Ward

This study provides a systematic analysis of the effect of common acid sulfate soil (ASS) sample pre-treatments (namely freezing, oven drying, and grinding) on chromium-reducible sulfur (SCR) and water-soluble sulfate determinations. The results show that oven drying and hand grinding of the samples prior to analysis resulted in a decrease in SCR (i.e. up to 20% compared to those of frozen samples). This lower SCR value was partly due to the oxidation of sulfides in the oven. For oven-dried ASS materials, more intensive grinding in a ring mill increased SCR values, most likely by abrading coatings from pyrite grains. For …

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The Response Of Partially Oxidised Acid Sulfate Soil Materials To Anoxia, Nicholas Ward, Leigh Sullivan, Richard Bush Oct 2013

The Response Of Partially Oxidised Acid Sulfate Soil Materials To Anoxia, Nicholas Ward, Leigh Sullivan, Richard Bush

Dr Nicholas J Ward

Four acid sulfate soil (ASS) materials were subjected to anoxia after varying periods of oxidation to determine the geochemical response of these types of soils to flooding. The response of the partially oxidised ASS materials to the exclusion of oxygen was variable. The rate of sulfide oxidation, acidification, and the production of soluble oxidation products such as sulfate, iron, and aluminium generally decreased markedly when subjected to anoxia. However, especially in the highly acidic ASS materials (i.e. pH 3+. Rapid sulfide re-formation occurred in the peat ASS material that had been oxidised for 63 days, with 0.47% reduced inorganic sulfur …

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Sulfide Oxidation And Acidification Of Acid Sulfate Soil Materials Treated With Caco3 And Seawater-Neutralised Bauxite Refinery Residue, Nicholas Ward, Leigh Sullivan, Richard Bush Oct 2013

Sulfide Oxidation And Acidification Of Acid Sulfate Soil Materials Treated With Caco3 And Seawater-Neutralised Bauxite Refinery Residue, Nicholas Ward, Leigh Sullivan, Richard Bush

Dr Nicholas J Ward

Acid sulfate soil (ASS) materials that are subject to oxidation are often treated with neutralising agents to minimise the export of acidity that may result from pyrite oxidation. The effects of additions of both CaCO3 and seawater-neutralised bauxite refinery residue (SNBRR) on the oxidation of sulfides and acidification were assessed for 4 ASS materials using laboratory incubation experiments. As the application of sub-optimal rates of neutralising materials can occur for a variety of reasons, the effect of application rates were also examined. Two application rates were chosen; a sub-optimal rate [approximately 20% of the theoretical neutralising requirement (NR)] and …

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Assessment Of Peroxide Oxidation For Acid Sulfate Soil Analysis. 2. Acidity Determination, Nicholas Ward, Leigh Sullivan, Richard Bush, Chuxia Lin Oct 2013

Assessment Of Peroxide Oxidation For Acid Sulfate Soil Analysis. 2. Acidity Determination, Nicholas Ward, Leigh Sullivan, Richard Bush, Chuxia Lin

Dr Nicholas J Ward

Total sulfidic acidity (TSA) and total potential acidity (TPA) are derived from peroxide oxidation of acid sulfate soil materials (ASS), and are measures of the sulfidic acidity and the net acidity (net acidity = sulfidic acidity + actual acidity – acid neutralising capacity), respectively. The TSA and TPA of 4 ASS materials were determined using a variety of peroxide oxidation procedures and compared with the sulfidic acidity and net acidity derived from the use of an acid–base accounting model. TSA and TPA values both varied greatly with each peroxide oxidation method used, and both measures were found to substantially underestimate …

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Monosulfidic Black Ooze Accumulations In Sediments Of The Geographe Bay Area, Western Australia, Nicholas Ward, Richard Bush, Edward Burton, S Appleyard, S Wong, Leigh Sullivan, Paul Cheeseman Oct 2013

Monosulfidic Black Ooze Accumulations In Sediments Of The Geographe Bay Area, Western Australia, Nicholas Ward, Richard Bush, Edward Burton, S Appleyard, S Wong, Leigh Sullivan, Paul Cheeseman

Dr Nicholas J Ward

Mobilisation of sedimentary monosulfidic black ooze (MBO) may result in rapid deoxygenation and acidification of surface waters, and release of potentially toxic metals. This study examines the extent and nature of MBO accumulation in the Geographe Bay area, Western Australia. MBO accumulations were found to be widespread in benthic sediments of the Geographe Bay area with acid-volatile sulfide (AVS) contents as high as 320 μmol g−1. The MBO materials often had unusually high dissolved sulfide (S−II) concentrations in their pore-waters (up to 610 mg L−1) and elevated elemental sulfur (S0) contents (up to 51 μmol g−1). Dissolved S−II is able …

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Improved Identification Of Sulfidic Soil Materials By A Modified Incubation Method, Leigh Sullivan, Nicholas Ward, Richard Bush, Edward Burton Oct 2013

Improved Identification Of Sulfidic Soil Materials By A Modified Incubation Method, Leigh Sullivan, Nicholas Ward, Richard Bush, Edward Burton

Dr Nicholas J Ward

This study examines the acidification behaviour and rate of sulfidic-sulfur oxidation in the incubation method that is currently used in soil taxonomies to identify sulfidic materials, for some clayey textured soil materials. ‘Sulfidic’ in these taxonomies identifies that a soil material is capable of becoming extremely acidic (i.e. pH < 4) as a result of oxidation of sulfide minerals contained in that soil material. As well as examining incubation slabs of acid sulfate soil materials with the standard 10 mm thickness, the utility of thinner (i.e. 2 mm thick) incubation slabs of these soil materials for identification of sulfidic soil materials …

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Soil Ph, Oxygen Availability, And The Rate Of Sulfide Oxidation In Acid Sulfate Soil Materials: Implications For Environmental Hazard Assessment, Nicholas Ward, Leigh Sullivan, Richard Bush Oct 2013

Soil Ph, Oxygen Availability, And The Rate Of Sulfide Oxidation In Acid Sulfate Soil Materials: Implications For Environmental Hazard Assessment, Nicholas Ward, Leigh Sullivan, Richard Bush

Dr Nicholas J Ward

The potential environmental hazard of acid sulfate soil (ASS) materials is directly related to both the net acidity and the rate that actual acidity is released from these soil materials into the environment. While current environmental hazard assessment techniques for ASS materials are able to quantify the net acidity, they do not take account of differences in the rate of sulfide oxidation (the dominant source of actual acidity) and differences in the rate of acidification. In this study the rate of sulfide oxidation during incubation was examined for 4 ASS materials. The effect of pH and oxygen availability on the …

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The Process Of Sulfide Oxidation In Some Acid Sulfate Soil Materials, Nicholas Ward, Leigh Sullivan, Diane Fyfe, Richard Bush, Angus Ferguson Oct 2013

The Process Of Sulfide Oxidation In Some Acid Sulfate Soil Materials, Nicholas Ward, Leigh Sullivan, Diane Fyfe, Richard Bush, Angus Ferguson

Dr Nicholas J Ward

The process of sulfide oxidation in acid sulfate soils (ASS) is complex, involving the formation of numerous oxidation products. In this study the sulfide oxidation process was examined in 2 ASS materials over a period of 36 days using laboratory incubation experiments. Both ASS materials experienced substantial sulfide oxidation and acidification during incubation. The oxidation of pyrite was the primary cause of acidification in these ASS materials. Although a decrease in magnetic susceptibility (χ) over the initial 4 days of incubation suggested the rapid oxidation of ferromagnetic iron monosulfide greigite (Fe3S4), the total acid volatile sulfur …

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Assessment Of Peroxide Oxidation For Acid Sulfate Soil Analysis. 1. Reduced Inorganic Sulfur, Nicholas Ward, Leigh Sullivan, Richard Bush, Chuxia Lin Oct 2013

Assessment Of Peroxide Oxidation For Acid Sulfate Soil Analysis. 1. Reduced Inorganic Sulfur, Nicholas Ward, Leigh Sullivan, Richard Bush, Chuxia Lin

Dr Nicholas J Ward

The reduced inorganic sulfur fraction of 4 acid sulfate soil (ASS) materials was quantified using a variety of peroxide oxidation procedures. The temperature and duration of the peroxide oxidation were found to markedly affect the peroxide oxidisable sulfur determination. For 3 ASS materials with low total carbon content (i.e. <2.5% C), peroxide oxidisable sulfur underestimated the reduced inorganic sulfur fraction, with the peroxide oxidisable sulfur determinations being as low as 42% of those determined using chromium reducible sulfur technique. The precipitation of jarosite during peroxide oxidation was a major factor contributing to the underestimation of reduced inorganic sulfur in these materials. Apparent losses of sulfur of approximately 25% on average occurred during peroxide oxidation budget accounting; this also contributed towards the observed underestimation of reduced inorganic sulfur. It is most likely that these unaccounted losses are due to atmospheric losses of sulfur. In a peat ASS, one of the peroxide oxidation methods overestimated the reduced inorganic sulfur fraction and was attributed to the release of a large reserve of organic sulfur in this material by the peroxide. This study shows the peroxide oxidation methods examined here are subject to substantial interferences. Consequently these peroxide oxidation methods are unable to reliably provide accurate measurements of the reduced inorganic sulfur fraction in ASS materials

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Limits Of Luminescence Dating: An Update Regarding Quartz Of The Southern Alps Of New Zealand And The Olympic Mountains, Washington, Usa, Cianna Wyshnytzky, Tammy Rittenour Oct 2013

Limits Of Luminescence Dating: An Update Regarding Quartz Of The Southern Alps Of New Zealand And The Olympic Mountains, Washington, Usa, Cianna Wyshnytzky, Tammy Rittenour

Cianna E Wyshnytzky

Late Pleistocene glacial sediments from the South Fork Hoh River valley in the Olympic Mountains, Washington, USA and the Lake Hawea valley in the Southern Alps, New Zealand were dated using optically stimulated luminescence (OSL) on quartz and infrared stimulated luminescence (IRSL) on feldspar sand from 2011-2013. High sediment supply (typical of glacial environments), short transport distances, and sediment newly eroded from bedrock sources were expected to pose problems for luminescence dating in these locations. Samples were collected from a variety of depositional environments and inferred distances from the ice-front to assess how luminescence signals may vary due to these …

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Steady-State Aerosol Distributions In The Extra-Tropical, Lower Stratosphere And The Processes That Maintain Them, J. Wilson, Shan-Hu Lee, J. Reeves, C. Brock, H. Jonsson, B. Lafleur, M. Loewenstein, J. Podolske, E. Atlas, K. Boering, G. Toon, D. Fahey, T. Bui, G. Diskin, F. Moore Oct 2013

Steady-State Aerosol Distributions In The Extra-Tropical, Lower Stratosphere And The Processes That Maintain Them, J. Wilson, Shan-Hu Lee, J. Reeves, C. Brock, H. Jonsson, B. Lafleur, M. Loewenstein, J. Podolske, E. Atlas, K. Boering, G. Toon, D. Fahey, T. Bui, G. Diskin, F. Moore

Shan-Hu Lee

Measurements of aerosol, N2O and OCS made in the Northern Hemisphere below 21 km altitude following the eruption of Pinatubo are presented and analyzed. After September 1999, the oxidation of OCS and sedimentation of particles in the extra-tropical overworld north of 45 N are found to maintain the aerosol in a steady state. This analysis empirically links precursor gas to aerosol abundance throughout this region. These processes are tracked with age-of-air which offers advantages over tracking as a function of latitude and altitude. In the extra-tropical, lowermost stratosphere, normalized volume distributions appear constant in time after the fall of 1999. …

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Laboratory Studies Of H2so4/H2o Binary Homogeneous Nucleation From The So2+Oh Reaction: Evaluation Of The Experimental Setup And Preliminary Results, L. Young, D. Benson, F. Kameel, J. Pierce, H. Junninen, M. Kulmala, Shan-Hu Lee Oct 2013

Laboratory Studies Of H2so4/H2o Binary Homogeneous Nucleation From The So2+Oh Reaction: Evaluation Of The Experimental Setup And Preliminary Results, L. Young, D. Benson, F. Kameel, J. Pierce, H. Junninen, M. Kulmala, Shan-Hu Lee

Shan-Hu Lee

Binary homogeneous nucleation (BHN) of sulphuric acid and water (H2SO4/H2O) is one of the most important atmospheric nucleation processes, but laboratory observations of this nucleation process are very limited and there are also large discrepancies between different laboratory studies. The difficulties associated with these experiments include wall loss of H2SO4 and uncertainties in estimation of H2SO4 concentration ([H2SO4]) involved in nucleation. We have developed a new laboratory nucleation setup to study H2SO4/H2O BHN kinetics and provide relatively constrained [H2SO4] needed for nucleation. H2SO4 is produced from the SO2+OH→HSO3 reaction and OH radicals are produced from water vapor UV absorption. The …

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Ternary Homogeneous Nucleation Of H2so4, Nh3, And H2o Under Conditions Relevant To The Lower Troposphere, D. Benson, J. Yu, A. Markovich, Shan-Hu Lee Oct 2013

Ternary Homogeneous Nucleation Of H2so4, Nh3, And H2o Under Conditions Relevant To The Lower Troposphere, D. Benson, J. Yu, A. Markovich, Shan-Hu Lee

Shan-Hu Lee

Ternary homogeneous nucleation (THN) of H2SO4, NH3 and H2O has been used to explain new particle formation in various atmospheric regions, yet laboratory measurements of THN have failed to reproduce atmospheric observations. Here, we report first laboratory observations of THN made under conditions relevant to the lower troposphere ([H2SO4] of 106–107 cm−3, [NH3] of 0.08–20 ppbv, and a temperature of 288 K). Our observations show that NH3 can enhance atmospheric H2SO4aerosol nucleation and the enhancement factor (EF) in nucleation rate (J) due to NH3 (the ratio of Jmeasured with vs. without NH3) increases linearly with increasing [NH3] and increases with …

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The Effects Of Airmass History On New Particle Formation In The Free Troposphere: Case Studies, D. Benson, Li-Hao Young, Shan-Hu Lee, T. Campos, D. Rogers, J. Jensen Oct 2013

The Effects Of Airmass History On New Particle Formation In The Free Troposphere: Case Studies, D. Benson, Li-Hao Young, Shan-Hu Lee, T. Campos, D. Rogers, J. Jensen

Shan-Hu Lee

Recent aircraft studies showed that new particle formation (NPF) is very active in the free troposphere. And, these observations lead to a new question: when does NPF not occur? Here, we provide case studies to show how different meteorological parameters affect NPF in the upper troposphere, using the aerosol size distributions measured at latitudes from 18° N–52° N and altitudes up to 14 km during the NSF/NCAR GV Progressive Science Missions. About 95% of the total samples showed the NPF feature with median number concentrations of particles with diameters from 4 to 9 nm (N4–9), 288±199 cm−3, and the total …

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Bayesian Analysis Of Hypothesis Testing Problems For General Population: A Kullback–Leibler Alternative, Naveen Bansal, Gholamhossein Hamedani, Ru Sheng Oct 2013

Bayesian Analysis Of Hypothesis Testing Problems For General Population: A Kullback–Leibler Alternative, Naveen Bansal, Gholamhossein Hamedani, Ru Sheng

Naveen Bansal

We consider a hypothesis problem with directional alternatives. We approach the problem from a Bayesian decision theoretic point of view and consider a situation when one side of the alternatives is more important or more probable than the other. We develop a general Bayesian framework by specifying a mixture prior structure and a loss function related to the Kullback–Leibler divergence. This Bayesian decision method is applied to Normal and Poisson populations. Simulations are performed to compare the performance of the proposed method with that of a method based on a classical z-test and a Bayesian method based on the …

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Creating Composite Age Groups To Smooth Percentile Rank Distributions Of Small Samples, Francesca Lopez, Amy Olson, Naveen Bansal Oct 2013

Creating Composite Age Groups To Smooth Percentile Rank Distributions Of Small Samples, Francesca Lopez, Amy Olson, Naveen Bansal

Naveen Bansal

Individually administered tests are often normed on small samples, a process that may result in irregularities within and across various age or grade distributions. Test users often smooth distributions guided by Thurstone assumptions (normality and linearity) to result in norms that adhere to assumptions made about how the data should look. Test users, however, may come across particular tests or sets of data in which the Thurstone assumptions are untenable. When users expect deviations from normality within age or grade, an alternate method is desirable. The authors present a relatively simple procedure that allows the user to treat observed raw …

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Community Websites And What Makes Them Sustainable: Evidence From Australia, Alison Norris, Mark Freeman Oct 2013

Community Websites And What Makes Them Sustainable: Evidence From Australia, Alison Norris, Mark Freeman

Dr Mark Freeman

Australia is leading the way in promoting the use of the Internet as a means of strengthening local communities. The Australian Domain Name Authority (auDA) has announced the release of Community Geographic Domain Names (CGDN), to be solely used by not-for-profit, self-funded local community groups. As Australian communities attempt to establish a management group and develop a website under this concept, they are faced with a range of issues. Longitudinal case study research has been conducted on three communities involved in a trial of the CGDN model, in the first research of this type. Based on data collected from the …

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Scene-Adaptive Configuration Of Two Cameras Using The Correspondence Field Function, Farzad Safaei, Payam Mokhtarian, Hooman Shidanshidi, Wanqing Li, Mohammad-Reza Namazi-Rad, Amir Mousavinia Sep 2013

Scene-Adaptive Configuration Of Two Cameras Using The Correspondence Field Function, Farzad Safaei, Payam Mokhtarian, Hooman Shidanshidi, Wanqing Li, Mohammad-Reza Namazi-Rad, Amir Mousavinia

Payam Mokhtarian

In a free viewpoint video system, the scene is captured by a number of cameras and it would be desirable to optimize the configuration of cameras, such as their location or orientation, to improve the rendering quality. This paper introduces a mathematical representation of the multi-camera geometry, called the correspondence field (CF), which can be used to quantify the suitability of a camera configuration for a given arrangement of objects in the scene. The correspondence field describes the spatial topology of the intersecting rays of cameras, arranged as a number of layers or surfaces in the field of view of …

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Photocatalytic Oxidation Of Organic Pollutants Catalyzed By An Iron Complex At Biocompatible Ph Values: Using O2 As Main Oxidant In A Fenton-Like Reaction, Xi Chen, Wanhong Ma, Jing Li, Zhaohui Wang, Chungcheng Chen, Hongwei Ji, Jincai Zhao Sep 2013

Photocatalytic Oxidation Of Organic Pollutants Catalyzed By An Iron Complex At Biocompatible Ph Values: Using O2 As Main Oxidant In A Fenton-Like Reaction, Xi Chen, Wanhong Ma, Jing Li, Zhaohui Wang, Chungcheng Chen, Hongwei Ji, Jincai Zhao

Dr Zhaohui Wang

A red iron(II) 4,4′-dicarboxy-2,2′-bipyridine complex ([FeII(dcbpy)3]) was investigated as an extraordinary Fenton catalyst capable of activating much more molecular O2 to mineralize organic pollutants in water at biocompatible pH values under visible irradiation. Eight representative organic pollutants were effectively degraded in the presence of this catalyst with high turnover number (368−2000). The flexible bifunctional coordination mode (N donor for ferrous ion and O donor for ferric form) devoted by the ligand dcbpy should be responsible for the preservation of iron(II/III) catalysis in such a neutral pH condition, whereas any substitution of the 4,4′-carboxylic groups in …

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Sensitization Of Titania Semiconductor: A Promising Strategy To Utilize Visible Light, Zhaohui Wang, Wanhong Ma, Chuncheng Chen, Jincai Zhao Sep 2013

Sensitization Of Titania Semiconductor: A Promising Strategy To Utilize Visible Light, Zhaohui Wang, Wanhong Ma, Chuncheng Chen, Jincai Zhao

Dr Zhaohui Wang

No abstract provided.

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Comparative Study Of Interaction Between Pyrite And Cysteine By Thermogravimetric And Electrochemical Techniques, Zhaohui Wang, Xuehui Xie, Shengmu Xiao, Jianshe Liu Sep 2013

Comparative Study Of Interaction Between Pyrite And Cysteine By Thermogravimetric And Electrochemical Techniques, Zhaohui Wang, Xuehui Xie, Shengmu Xiao, Jianshe Liu

Dr Zhaohui Wang

Adsorption mechanism of l-cysteine on pyrite was investigated by thermogravimetric and electrochemical techniques. TG curves provided the direct evidence for chemisorption of cysteine on pyrite surface. Once cysteine adsorbed to pyrite surface, Ecorr (corrosion potential) sharply lowered whereas Icorr (corrosion current) increased rapidly. Pyrite became more susceptible to be oxidized even at lower potential as cysteine was added. However, the mechanism for pyrite oxidation does not fundamentally change, although cysteine can obviously accelerate oxidation rate of pyrite. These findings have important implications for understanding the mechanism of bacterial adhesion to pyrite and even metal sulfide bioleaching.

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Effects Of Chloride Ion On Degradation Of Acid Orange 7 By Sulfate Radical-Based Advanced Oxidation Process: Implications For Formation Of Chlorinated Aromatic Compounds, Ruixia Yuan, Sadiqua Ramjaun, Zhaohui Wang, Jianshe Liu Sep 2013

Effects Of Chloride Ion On Degradation Of Acid Orange 7 By Sulfate Radical-Based Advanced Oxidation Process: Implications For Formation Of Chlorinated Aromatic Compounds, Ruixia Yuan, Sadiqua Ramjaun, Zhaohui Wang, Jianshe Liu

Dr Zhaohui Wang

Sodium chloride is a common salt used during textile wet processes. Here a dual effect of chloride (i.e. inhibitory and accelerating effect) on azo dye (Acid Orange 7, AO7) degradation in an emerging cobalt/peroxymonosulfate (Co/PMS) advanced oxidation process (AOP) was reported. Compared to OH-based AOPs, high concentrations of chloride (>5 mM) can significantly enhance dye decoloration independent of the presence of the Co2+ catalyst, but did greatly inhibit dye mineralization to an extent which was closely dependent upon the chloride content. Both UV–vis absorbance spectra and AOX determination indicated the formation of some refractory byproducts. Some chlorinated aromatic compounds, …

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Light-Assisted Decomposition Of Dyes Over Iron-Bearing Soil Clays In The Presence Of H2o2, Zhaohui Wang, Wanhong Ma, Chuncheng Chen, Jincai Zhao Sep 2013

Light-Assisted Decomposition Of Dyes Over Iron-Bearing Soil Clays In The Presence Of H2o2, Zhaohui Wang, Wanhong Ma, Chuncheng Chen, Jincai Zhao

Dr Zhaohui Wang

Four types of soil clays from different sites in China have been chosen to simulate chemical remediation of soils contaminated with dyes by light-assisted Fenton-like method. X-Ray diffraction (XRD), X-ray photoelectron spectroscopic (XPS) and electron spin resonance (ESR) measurements indicated that these soil clays contain iron oxides such as magnetite and hematite, where nondistorted iron active sites (ESR spectra, g = 2.3) predominate. Upon visible or UV irradiation, the soil clays were very effective for the degradation of nonbiodegradable cationic dyes such as Rhodamine B (RhB) by activating H2O2 at neutral pH. The photodegradation rates of RhB …

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