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Sample records for hematitic chert jasper

  1. Geochemistry and jasper beds from the Ordovician Løkken ophiolite, Norway: origin of proximal and distal siliceous exhalites

    Science.gov (United States)

    Grenne, Tor; Slack, John F.

    2005-01-01

    Stratiform beds of jasper (hematitic chert), composed essentially of SiO2 (69-95 wt %) and Fe2O3 (3-25 wt %), can be traced several kilometers along strike in the Ordovician L??kken ophiolite, Norway. These siliceous beds are closely associated with volcanogenic massive sulfide (VMS) deposits and are interpreted as sea-floor gels that were deposited by fallout from hydrothermal plumes in silica-rich seawater, in which plume-derived Fe oxyhydroxide particles promoted flocculation and rapid settling of large (???200 ??m) colloidal particles of silica-iron oxyhydroxide. Concentrations of chalcophile elements in the jasper beds are at the parts per million level implying that sulfide particle fallout was insignificant and that the Si-Fe gel-forming plumes were mainly derived from intermediate- (100??-250??C) to high-temperature (>250??) white smoker-type vents with high Fe/S ratios. The interpreted setting is similar to that of the Lau basin, where high-temperature (280??-334??C) white smoker venting alternates or overlaps with sulfide mound-forming black smoker venting. Ratios of Al, Sc, Th, Hf, and REE to iron are very low and show that the detrital input was <0.1 percent of the bulk jasper. Most jasper beds are enriched in U, V, P, and Mo relative to the North American Shale Composite, reflecting a predominantly seawater source, whereas REE distribution patterns (positive Eu and negative Ce anomalies) reflect variable mixing of hydrothermal solutions with oxic seawater at dilution ratios of ???102 to 104. Trace element variations in the gel precursor to the jasper are thought to have been controlled by coprecipitation and/or adsorption by Fe oxyhydroxide particles that formed by the oxidation of hydrothermal Fe2+ within the variably seawater-diluted hydrothermal plume(s). Thick jasper layers near the H??ydal VMS orebody show distinct positive As/Fe and Sb/Fe anomalies that are attributed to near-vent rapid settling of Si-Fe particles derived from As- and Sb

  2. Stable isotope geochemistry of deep sea cherts

    Energy Technology Data Exchange (ETDEWEB)

    Kolodny, Y; Epstein, S [California Inst. of Tech., Pasadena (USA). Div. of Geological Sciences

    1976-10-01

    Seventy four samples of DSDP (Deep Sea Drilling Project) recovered cherts of Jurassic to Miocene age from varying locations, and 27 samples of on-land exposed cherts were analyzed for the isotopic composition of their oxygen and hydrogen. These studies were accompanied by mineralogical analyses and some isotopic analyses of the coexisting carbonates. delta/sup 18/0 of chert ranges between 27 and 39 parts per thousand relative to SMOW, delta/sup 18/0 of porcellanite - between 30 and 42 parts per thousand. The consistent enrichment of opal-CT in porcellanites in /sup 18/0 with respect to coexisting microcrystalline quartz in chert is probably a reflection of a different temperature (depth) of diagenesis of the two phases. delta/sup 18/0 of deep sea cherts generally decrease with increasing age, indicating an overall cooling of the ocean bottom during the last 150 m.y. A comparison of this trend with that recorded by benthonic foraminifera (Douglas et al., Initial Reports of the Deep Sea Drilling Project; 32:509(1975)) indicates the possibility of delta/sup 18/0 in deep sea cherts not being frozen in until several tens of millions of years after deposition. Cherts of any Age show a spread of delta/sup 18/0 values, increasing diagenesis being reflected in a lowering of delta/sup 18/0. Drusy quartz has the lowest delta/sup 18/0 values. On land exposed cherts are consistently depleted in /sup 18/0 in comparison to their deep sea time equivalent cherts. Water extracted from deep sea cherts ranges between 0.5 and 1.4 wt%. deltaD of this water ranges between -78 and -95 parts per thousand and is not a function of delta/sup 18/0 of the cherts (or the temperature of their formation).

  3. Diffusive retention of atmospheric gases in chert

    Science.gov (United States)

    Pettitt, E.; Cherniak, D. J.; Watson, E. B.; Schaller, M. F.

    2016-12-01

    Throughout Earth's history, the volatile contents (N2, CO2, Ar) of both deep and shallow terrestrial reservoirs has been dynamic. Volatiles are important chemical constituents because they play a significant role in regulating Earth's climate, mediating the evolution of complex life, and controlling the properties of minerals and rocks. Estimating levels of atmospheric volatiles in the deep geological past requires interrogation of materials that have acquired and retained a chemical memory from that time. Cherts have the potential to trap atmospheric components during formation and later release those gases for analysis in the laboratory. However, cherts have been underexploited in this regard, partly because their ability to retain a record of volatile components has not been adequately evaluated. Before cherts can be reliably used as indicators of past levels of major atmospheric gases, it is crucial that we understand the diffusive retentiveness of these cryptocrystalline silica phases. As the first step toward quantifying the diffusivity and solubility of carbon dioxide and nitrogen in chert, we have performed 1-atmosphere diffusive-uptake experiments at temperatures up to 450°C. Depth profiles of in-diffusing gases are measured by nuclear reaction analysis (NRA) to help us understand the molecular-scale transport of volatiles and thus the validity of using chert-bound volatiles to record information about Earth history. Data collected to date suggest that at least some cherts are ideal storage containers and can retain volatiles for a geologically long time. In addition to these diffusion experiments, preliminary online-crush fast-scan measurements using a quadrupole mass spectrometer indicate that atmospheric volatiles are released upon crushing various chert samples. By coupling such volatile-release measurements made by mass spectrometry with diffusion experiments, we are uniquely able to address the storage and fidelity of volatiles bound in crustal

  4. Astronomical cycle origin of bedded chert: A middle Triassic bedded chert sequence, Inuyama, Japan

    Science.gov (United States)

    Ikeda, Masayuki; Tada, Ryuji; Sakuma, Hironobu

    2010-09-01

    Astronomical forcing is one of the main drivers of climate change, and astronomical cyclicity recorded in sediments provides a clue to understand the dynamics of the global climate system. Bedded cherts consist of rhythmic alternations of chert and shale beds. Although previous studies have hypothesized that the origin of bedded chert is related to astronomical cycles (e.g. Fischer, 1976; Hori et al., 1993), conclusive proof remains elusive. To explore this possibility, we established a continuous, high-resolution lithostratigraphy of middle Triassic bedded chert in Central Japan. The average duration of each chert-shale couplet is 20 kyr, similar to that of the precession cycle. Spectral analysis of a bed number series of thickness variations in chert beds was performed assuming that each chert-shale couplet represents a 20-kyr precession cycle. The results reveal cycles involving approximately 200, 20, 5, and 2-3 beds, corresponding to periodicities of approximately 4000, 400, 100, and 40-60 kyr, respectively. By further assuming that the 20-bed cycle represents a 405-kyr eccentricity cycle of constant and stable periodicity, we converted the bed number series to a time series. Spectral analysis of the time series revealed distinct periodicities of 3600, 117, 97, and 38 kyr, in addition to 405 kyr. Besides 3600 kyr, these periodicities agree well with the 120, 95, and 37 kyr periodicities for eccentricity cycles and the obliquity cycle during the Triassic. Moreover, we detected amplitude modulation of the approximately 100-kyr cycle of thickness variations in chert beds with a 405-kyr periodicity, which may correspond to amplitude modulation of 100-kyr climatic precession cycle with the 405-kyr periodicity. The approximately 3600-kyr periodicity described above and 1800-kyr periodicity manifested as the amplitude modulation of the 405-kyr cycle are correlated to present-day long-term eccentricity cycles of 2400 and 4800 kyr evolved by chaotic behavior of solar

  5. Jasper Zoova ja Kiwa korraldavad videodisko

    Index Scriptorium Estoniae

    1999-01-01

    14. X klubis 'Võitlev Sõna' Jasper Zoova ja Kiwa korraldatud üritus 'Videodisko', alapealkirjaga 'The Best of Nervous Cowboys'. Kumbki kunstnik näitab pooletunnist retrospektiivi oma videotööde paremikust ning pärast seanssi saab vaadata videosalvestisi kunstnike näitustest

  6. DIE EKSISTENSIEFILOSOFIE VAN KARL JASPERS. ENKELE ...

    African Journals Online (AJOL)

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    Kierkegaard en Nietzsche, Max Weber en Dilthey, om maar enkeles te noem, en 5.) Jaspers se persoonlike beskouing oor die roe ping en die taak van die Filosofie, sy aanvoeling van die filosofiese problematiek en sy grondhouding teenoor die eksistensiële verbonden- hede. Die woord van Fichte, naamlik dat die Filosofie ...

  7. Freedom and mystery: an intellectual history of Jaspers' General Psychopathology.

    Science.gov (United States)

    Bormuth, Matthias

    2013-01-01

    The Kantian idea of freedom was introduced to psychiatry methodologically by Karl Jaspers. It influenced the genesis and design of his doctrine of understanding, General Psychopathology, even more decisively than Nietzsche's topos of resentment did. This article places Jaspers' work in the framework of a history of ideas. It begins by pursuing Nietzsche's perspective in the context of Darwinism, then focuses on the role concealed resentment played for Jaspers' genealogical concept of understanding in the first (1913) edition of General Psychopathology, which is primarily oriented towards Max Weber, before examining the idea of Kantian freedom, which was to become crucial for Jaspers' later work. The antinomy of freedom already shapes the suicidology contained in Jaspers' Philosophy of 1931. The idea gains prominence in the final, philosophically grounded revision of GeneralPsychopathology published in 1941/1942. Jaspers' reception of Kantian idealism leads him to develop a concept of critical understanding that clearly distinguishes itself from speculative understanding, whose hazards Jaspers illustrates on the basis of Viktor von Weizsäcker's theory of medicine. This goes far beyond Kant, embracing Schelling and Hegel philosophically. As it were, Jaspers and von Weizsäcker represent critical and postcritical thought in psychopathology and psychosomatics. The epilogue sums up by placing the inquiry in the context of Jaspers' life and work. © 2013 S. Karger AG, Basel.

  8. Terrestrial invertebrates in the Rhynie chert ecosystem.

    Science.gov (United States)

    Dunlop, Jason A; Garwood, Russell J

    2018-02-05

    The Early Devonian Rhynie and Windyfield cherts remain a key locality for understanding early life and ecology on land. They host the oldest unequivocal nematode worm (Nematoda), which may also offer the earliest evidence for herbivory via plant parasitism. The trigonotarbids (Arachnida: Trigonotarbida) preserve the oldest book lungs and were probably predators that practiced liquid feeding. The oldest mites (Arachnida: Acariformes) are represented by taxa which include mycophages and predators on nematodes today. The earliest harvestman (Arachnida: Opiliones) includes the first preserved tracheae, and male and female genitalia. Myriapods are represented by a scutigeromorph centipede (Chilopoda: Scutigeromorpha), probably a cursorial predator on the substrate, and a putative millipede (Diplopoda). The oldest springtails (Hexapoda: Collembola) were probably mycophages, and another hexapod of uncertain affinities preserves a gut infill of phytodebris. The first true insects (Hexapoda: Insecta) are represented by a species known from chewing (non-carnivorous?) mandibles. Coprolites also provide insights into diet, and we challenge previous assumptions that several taxa were spore-feeders. Rhynie appears to preserve a largely intact community of terrestrial animals, although some expected groups are absent. The known fossils are (ecologically) consistent with at least part of the fauna found around modern Icelandic hot springs.This article is part of a discussion meeting issue 'The Rhynie cherts: our earliest terrestrial ecosystem revisited'. © 2017 The Author(s).

  9. Shikarpur lithic assemblage: New questions regarding Rohri chert blade production

    Directory of Open Access Journals (Sweden)

    Charusmita Gadekar

    2014-03-01

    Full Text Available Recent excavations at Shikarpur, a fortified Harappan site situated near the Gulf of Kuchchh in Gujarat, Western India, brought to light a large collection of Rohri chert blades.  Chert found in the Rohri hill near Sukkur in Sindh, central Pakistan is distinctive and easily identifiable. The wide distribution of standardized Rohri chert blades is often regarded as a testimony to the Harappan efficiency in long distance trade and craft production.  The possibility of localized production of Rohri chert blades in Gujarat is often negated due to the constraints of raw-material availability.  The absence of Rohri chert working debitage from most of the sites in Gujarat, has lent support to this position. The Shikarpur Rohri blade assemblage however incorporates more than 650 blades, a large fluted blade-core and a few Rohri chert debitage.  These have led the excavators to suggest that some of the blades found at Shikarpur were locally produced from raw materials brought to the site from the Rohri hills.  Typo-technological features of the Rohri chert assemblage from Shikarpur have been analysed in this background. These along with metrical features of the assemblage are compared with Rohri chert assemblages from other major Harappan sites in the region to check the validity of the proposed ‘limited local production’.

  10. Descriptive psychopathology, phenomenology, and the legacy of Karl Jaspers.

    Science.gov (United States)

    Häfner, Heinz

    2015-03-01

    With his early publications (1910-1913), Karl Jaspers created a comprehensive methodological arsenal for psychiatry, thus laying the foundation for descriptive psychopathology. Following Edmund Husserl, the founder of philosophical phenomenology, Jaspers introduced phenomenology into psychopathology as "static understanding," ie, the unprejudiced intuitive reproduction (Vergegenwärtigung) and description of conscious phenomena. In a longitudinal perspective, "genetic understanding" based on empathy reveals how mental phenomena arise from mental phenomena. Severance in understanding of, or alienation from, meaningful connections is seen as indicating illness or transition of a natural development into a somatic process. Jaspers opted for philosophy early. After three terms of law, he switched to studying medicine, came to psychopathology after very little training in psychiatry; to psychology without ever studying psychology; and to a chair in philosophy without ever studying philosophy. In the fourth and subsequent editions of his General Psychopathology, imbued by his existential philosophy, Jaspers partly abandoned the descriptive method.

  11. 57Fe Mössbauer analysis of the Upper Triassic-Lower Jurassic deep-sea chert: Paleo-redox history across the Triassic-Jurassic boundary and the Toarcian oceanic anoxic event

    International Nuclear Information System (INIS)

    Sato, Tomohiko; Isozaki, Yukio; Shozugawa, Katsumi; Seimiya, Kimiko; Matsuo, Motoyuki

    2012-01-01

    We investigated the paleo-redox change across the Triassic-Jurassic (T-J) boundary (∼200 Ma) and the Early Toarcian oceanic anoxic event (T-OAE; ∼183 Ma) recorded in the Upper Triassic to Lower Jurassic pelagic deep-sea cherts in the Inuyama area, Central Japan. The present 57 Fe Mössbauer spectroscopic analysis for these cherts identified five iron species, i.e., hematite (α-Fe 2 O 3 ), pyrite (FeS 2 ), paramagnetic Fe 3 +  , and two paramagnetic Fe 2 +  with different quadrupole splittings. The occurrence of hematite and pyrite in deep-sea cherts essentially indicates primary oxidizing and reducing depositional conditions, respectively. The results confirmed that oxidizing conditions persisted in deep-sea across the T-J boundary. In contrast, across the T-OAE, deep-sea environment shifted to reducing conditions. The first appearance of the gray pyrite-bearing chert marked the onset of the deep-sea oxygen-depletion in the middle Pliensbachian, i.e., clearly before the shallow-sea T-OAE.

  12. Surface mapping and drilling of extinct seafloor massive sulphide deposits (eSMS) from the TAG Hydrothermal Field, 26oN: A tale of two `Jaspers'

    Science.gov (United States)

    Stobbs, I. J.; Lusty, P.; Petersen, S.; Murton, B. J.

    2017-12-01

    Two extinct seafloor massive sulphide (eSMS) deposits within the TAG hydrothermal field, 26oN, mid-Atlantic ridge, were mapped and drilled: Southern Mound and the newly discovered `Rona Mound'. Surface mapping was undertaken by combining high definition video footage and high resolution bathymetry to interpret surface geological and geomorphological features. Drill core was recovered using the BGS RD2 robotic drilling rig. Surface mapping of the mounds revealed a superficial cover of carbonate and iron-oxyhydroxides sediments, observed to directly overly oxide coated sulphide material within fault scarps, which dissect the flanks of both mounds. Drilling at the summits of the mounds revealed similar stratigraphy to the mapping, with the addition of a coherent and dense layer of red-coloured silica-rich `jasper', up to 3m thick, underlying the sediments and overlying unoxidised massive sulphides. The jasper mineralogy is dominated by silica, with minor iron oxides and rare disseminated sulphides. It displays a range of complex textures including filamentous and dendritic iron oxides often coated in silica. Drill core samples show the material to be porous, but relatively impermeable. Strong and positive Eu (REE) anomalies indicates a hydrothermal origin with little evidence of a seawater signature (lack of negative Ce anomaly). Silica precipitation is associated with low temperature hydrothermal activity, chert and jasper materials are locally present within the nearby hydrothermally active TAG mound and are more widespread at low-temperature diffuse hydrothermal sites such as within the MESO field. We interpret the `jasper' layers to be a common product, formed during the waning, low temperature, stage of the hydrothermal cycle which may form an impermeable and resistant `cap' that protects the underlying massive sulphide ore body from oxidation and dissolution. The formation of a `jasper cap' could act automatically to preserve eSMS deposits when hydrothermal

  13. [The concept of "understanding" (Verstehen) in Karl Jaspers].

    Science.gov (United States)

    Villareal, Helena; Aragona, Massimiliano

    2014-01-01

    This article explores the relationship between empathy and psychopathology. It deals with the concept of "understanding" in Jaspers' General Psychopathology, 100 years after the publication of its first edition. The Jaspersian proposal has the person and his/her experience as its primary object of study, just as in Ortegas' vital reason. Jaspers' understanding is not rational but empathetic, based on the co-presence of emotional content and detailed descriptions. Jaspers' methodology is essentially pluralistic, considering both explanation and understanding, necessary for psychopathology. Despite certain limits, the concept of understanding is the backbone of the psychopathological reasoning, and has proven useful over a century of clinical practice. However, it needs a review covering the recent epistemological and clinical findings. "To be understandable" is a relational property that emerges from a semiotic process. Therefore, an effective psychology should encompass an inter-subjective process, and get away from strict rationalism.

  14. Thermoluminescent determination of prehistoric heat treatment of chert artifacts

    International Nuclear Information System (INIS)

    Melcher, C.L.; Zimmerman, D.W.

    1977-01-01

    In recent years archeologists have become interested in the extent to which prehistoric peoples heat-treated chert prior to shaping it into tools. Thermoluminescent determination of the radiation dose accumulated by an artifact since it was formed or last heated provides a simple, reliable test for such heat treatment. This test can be applied to single artifacts without the need for raw source material for comparison. Results on 25 artifacts from four sites indicate that, for many chert sources, color and luster are not useful indicators of heat treatment by prehistoric peoples

  15. Lead, cadmium, and zinc concentrations in plaster and mortar from structures in Jasper and Newton Counties, Missouri (Tri-State Mining District)

    Energy Technology Data Exchange (ETDEWEB)

    Perry, Phyllis M [Chemistry Department, Southwest Missouri State University, 901 S. National Avenue, Springfield, MO 65804 (United States); Pavlik, Jeffrey W [Chemistry Department, Southwest Missouri State University, 901 S. National Avenue, Springfield, MO 65804 (United States); Sheets, Ralph W [Chemistry Department, Southwest Missouri State University, 901 S. National Avenue, Springfield, MO 65804 (United States); Biagioni, Richard N [Chemistry Department, Southwest Missouri State University, 901 S. National Avenue, Springfield, MO 65804 (United States)

    2005-01-05

    The primary goal of this study was to evaluate anecdotal evidence that within Jasper and Newton Counties, Missouri, two counties within the Tri-State Mining District, granular mine tailings were commonly used in place of river sands in wall plasters and mortar. Interior wall plaster and mortar samples from structures in this mining district were analyzed for lead, cadmium, and zinc, and compared to samples from Springfield, MO (comparison site). The Jasper and Newton County samples showed elevated concentrations of the three elements, consistent with the inclusion of mine tailings, with a number of samples containing lead and cadmium at concentrations greater than EPA remediation targets for yard soil. X-ray diffraction studies showed the presence of the zinc ore minerals, sphalerite and hemimorphite, in high level samples. Thin section optical studies identified the major component of the aggregate as chert, a mineral abundant within the tailing piles. Because dust from crumbling plaster and mortar could represent an avenue for significant heavy metal exposure to building occupants, we suggest that there may be associated health consequences that should be further evaluated.

  16. Lead, cadmium, and zinc concentrations in plaster and mortar from structures in Jasper and Newton Counties, Missouri (Tri-State Mining District)

    International Nuclear Information System (INIS)

    Perry, Phyllis M.; Pavlik, Jeffrey W.; Sheets, Ralph W.; Biagioni, Richard N.

    2005-01-01

    The primary goal of this study was to evaluate anecdotal evidence that within Jasper and Newton Counties, Missouri, two counties within the Tri-State Mining District, granular mine tailings were commonly used in place of river sands in wall plasters and mortar. Interior wall plaster and mortar samples from structures in this mining district were analyzed for lead, cadmium, and zinc, and compared to samples from Springfield, MO (comparison site). The Jasper and Newton County samples showed elevated concentrations of the three elements, consistent with the inclusion of mine tailings, with a number of samples containing lead and cadmium at concentrations greater than EPA remediation targets for yard soil. X-ray diffraction studies showed the presence of the zinc ore minerals, sphalerite and hemimorphite, in high level samples. Thin section optical studies identified the major component of the aggregate as chert, a mineral abundant within the tailing piles. Because dust from crumbling plaster and mortar could represent an avenue for significant heavy metal exposure to building occupants, we suggest that there may be associated health consequences that should be further evaluated

  17. Joint Actinide Shock Physics Experimental Research (JASPER) Facility Update

    International Nuclear Information System (INIS)

    Conrad, C. H.; Miller, J.; Cowan, M.; Martinez, M.; Whitcomb, B.

    2003-01-01

    The JASPER Facility utilizes a Two-Stage Light Gas Gun to conduct equation-of-state(EOS) experiments on plutonium and other special nuclear materials. The overall facility will be discussed with emphasis on the Two-Stage Light Gas Gun characteristics and control interfaces and containment. The containment systems that were developed for this project will be presented

  18. Hannah Arendt and Karl Jaspers: The Time of Friendship

    Science.gov (United States)

    Nixon, Jon

    2016-01-01

    This paper provides an introduction to the enduring friendship between Hannah Arendt and Karl Jaspers. It shows how their intellectual development as public educators was sustained by their ongoing dialogue which flourished not in spite of but because of their huge differences of circumstance and personality. This friendship between two renowned…

  19. Magnetic properties of hematite nanoparticles

    DEFF Research Database (Denmark)

    Bødker, Franz; Hansen, Mikkel Fougt; Bender Koch, Christian

    2000-01-01

    The magnetic properties of hematite (alpha-Fe2O3) particles with sizes of about 16 nm have been studied by use of Mossbauer spectroscopy, magnetization measurements, and neutron diffraction. The nanoparticles are weakly ferromagnetic at temperatures at least down to 5 K with a spontaneous...... magnetization that is only slightly higher than that of weakly ferromagnetic bulk hematite. At T greater than or similar to 100 K the Mossbauer spectra contain a doublet, which is asymmetric due to magnetic relaxation in the presence of an electric field gradient in accordance with the Blume-Tjon model......, Simultaneous fitting of series of Mossbauer spectra obtained at temperatures from 5 K to well above the superparamagnetic blocking temperature allowed the estimation of the pre-exponential factor in Neel's expression for the superparamagnetic relaxation time, tau(0) = (6 +/- 4) X 10(-11) s and the magnetic...

  20. Geochemistry of the Late Paleozoic cherts in the Youjiang Basin: Implications for the basin evolution

    Directory of Open Access Journals (Sweden)

    Huang Hu

    2013-10-01

    Full Text Available We analyzed the major and rare earth element compositions of siliceous deposits from the Upper Devonian Liujiang Formation, Lower Carboniferous Luzhai Formation, Lower–Middle Permian Sidazhai Formation and Tapi Formation, which are widely distributed as bedded cherts in the interplatform basinal successions of the Youjiang Basin. The Liujiang Formation and Luzhai Formation cherts generally have high Al/(Al+Fe+Mn values (0.38–0.94 and are non-hydrothermal cherts. These cherts are generally characterized by moderately negative Ce anomalies and high Y/Ho values relatived to PAAS, indicating that the Youjiang Basin might have evolved into an open rift basin during the Late Devonian–Early Carboniferous. The Sidazhai Formation cherts from Ziyun generally have high Al/(Al+Fe+Mn values (0.60–0.78, suggesting negligible contribution from a hydrothermal component. The Sidazhai Formation cherts from Hechi and the Tapi Formation cherts from Malipo generally have low Al/(Al+Fe+Mn values (0.09–0.41, indicating an intense hydrothermal input. Relatived to the Sidazhai Formation cherts, the Tapi Formation cherts have higher Ce/Ce* values (0.68±0.19 and lower Y/Ho values (41.83±13.27, which may be affected by the terrigenous input from the Vietnam Block. The Sidazhai Formation cherts from Ziyun and Hechi exhibit negative Ce anomalies (0.43±0.12, 0.33±0.17, respectively with high Y/Ho values (57.44±16.20, 46.02±4.27, respectively, resembling the geochemical characteristics of open-ocean basin cherts. These cherts were deposited on a passive continental margin adjacent to the Babu branch ocean, which may have contributed to upwelling. Detailed spatial studies on geochemical characteristics of the Late Paleozoic cherts can unravel the evolution of the Youjiang Basin.

  1. [Jaspers and the problem of understanding: a plea for revision].

    Science.gov (United States)

    Brücher, K

    2012-04-01

    Understanding (Verstehen), as far as it is discussed explicitly in psychiatry, is based on Dilthey's dichotomy "nature we explain, the life of the soul we understand ( , 144). According to this doctrine, understanding is concerned with a person's inner life and consequently, its method consists in putting oneself in the other's position and reliving their experience. Jaspers' concept of understanding - which is regarded as definitive for psychiatry by advocates and opponents alike - is commonly interpreted according to this tradition as well. I shall argue here that this position does not stand up to scrutiny. It is a mistake to simplify Dilthey's concept of understanding to a form of mere psychologism. In fact, Jaspers practically tore this position down. In his own account, by contrast, he utilises Max Weber and Rickert to established a third realm in addition to a person's inner life on the one hand and their bodily nature on the other: the realm of the objective products of the human mind. It is this dimension that is essential for understanding. Such a transition from the dichotomy of explaining and understanding to a three-valued logic requires a radical rethinking of the traditional notion of understanding. Jaspers meets this demand but he does so only implicitly and not always consistently so that it might easily be missed. It is nonetheless crucial to see that Jaspers in fact rejects the hermeneutics of empathy which are commonly attributed to him and for which he is often criticised. In conclusion of this essay, I will suggest some implications of this - often overlooked - distinction for psychiatry and psychology. © Georg Thieme Verlag KG Stuttgart · New York.

  2. Joint Actinide Shock Physics Experimental Research (JASPER) Facility Overview

    International Nuclear Information System (INIS)

    Konrad, C.H.; Braddy, R.W.; Martinez, Mark

    2001-01-01

    The JASPER Facility will utilize a Two-Stage Light Gas Gun to conduct equation-of-state (EOS) experiments of plutonium and other special nuclear materials. The overall facility will be discussed with emphasis on the Two-Stage Light Gas Gun characteristics and mission. The primary and secondary containment systems that were developed for this project will be presented. Primary gun diagnostics and timing will also be discussed

  3. The theoretical root of Karl Jaspers' General Psychopathology. Part 2: The influence of Max Weber.

    Science.gov (United States)

    Kumazaki, Tsutomu

    2013-09-01

    The present study explores and compares Jaspers' methodology of psychopathology with Weber's methodology of sociology. In his works, Weber incorporated the arguments of many other researchers into his own methodology. Jaspers respected Weber as a mentor and presented arguments that were very similar to Weber's. Both Weber and Jaspers began from empathic understanding, but at the same time aimed for a rational and ideal-typical conceptualization. In addition, their methodologies were similar with respect to their detailed terminology. Such similarities cannot be seen with any other scholars. This suggests that Weber may have played an integral role as a mediator between his contemporary scholars and Jaspers. Thus, Weber may have had the most significant influence on Jaspers.

  4. Proposed open-pit mine threatens Jasper National Park

    Energy Technology Data Exchange (ETDEWEB)

    Mikelcic, S.

    1996-12-31

    Concerns by the Sierra Club, the Alberta Wilderness Association, and other environmental groups about the proposed Cheviot Mine are discussed. Cardinal River Coals, which is owned by Luscar Ltd. and Consolidated Coals of Pittsburgh, is proposing the mining operation, which includes 26 deep open pit mines of which 14 will not be backfilled. The mine extends to within 2 km of Jasper National Park`s border. Concerns about the mine include: disruption of an environmentally sensitive area, interference with grizzly bear movement and bighorn sheep habitat and diet, destruction of flora and fauna, and pollution of two major watersheds. Hearings for the mine commence in January 1997.

  5. La verdad comunicativa como reto creativo en Karl Jaspers.

    Directory of Open Access Journals (Sweden)

    Paula Arizpe

    2013-11-01

    Full Text Available This new approach to Jaspers' communicative truth as a creative challenge is focused on an analysis of the diverse modes of truth grasped by the self, first as an empirical conciousness, then as a free Existenz. This enables to develop a transcendent methodology to grow in freedom and enhances the horizons of the self integrating him to Trascendence, in a concrete tempo-spacial reference by means of game. This game becomes as open and challenging as he is capable to grasp truth in all its profoundness.

  6. La verdad comunicativa como reto creativo en Karl Jaspers.

    OpenAIRE

    Paula Arizpe

    2013-01-01

    This new approach to Jaspers' communicative truth as a creative challenge is focused on an analysis of the diverse modes of truth grasped by the self, first as an empirical conciousness, then as a free Existenz. This enables to develop a transcendent methodology to grow in freedom and enhances the horizons of the self integrating him to Trascendence, in a concrete tempo-spacial reference by means of game. This game becomes as open and challenging as he is capable to grasp truth in all its pro...

  7. Jasper Sharp: Jaapanile lähemal / intervjueerinud Joonas blogist filmijutt.blogspot.com

    Index Scriptorium Estoniae

    Sharp, Jasper, 1971-

    2011-01-01

    25.-28. augustini esmakordselt Tallinnas toimunud Jaapani sõltumatu filmi festivalist "East via Asia". Intervjuu festivali kuraatori, Inglismaalt pärist filmikriitiku Jasper Sharpiga, Jaapani sõltumatust kinost tänapäeval

  8. Requirements Doc for Refurb of JASPER Facility in B131HB

    Energy Technology Data Exchange (ETDEWEB)

    Knittel, Kenn M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-01-25

    The Joint Actinide Shock Physics Experimental Research (JASPER) Program target fabrication facility is currently located in building 131 (B131) of the Lawrence Livermore National Laboratory (LLNL). A portion of this current facility has been committed to another program as part of a larger effort to consolidate LLNL capabilities into newer facilities. This facility assembles precision targets for scientific studies at the Nevada National Security Site (NNSS). B131 is also going through a modernization project to upgrade the infrastructure and abate asbestos. These activities will interrupt the continuous target fabrication efforts for the JASPER Program. Several options are explored to meet the above conflicting requirements, with the final recommendation to prepare a new facility for JASPER target fabrication operations before modernization efforts begin in the current facility assigned to JASPER. This recommendation fits within all schedule constraints and minimizes the disruption to the JASPER Program. This option is not without risk, as it requires moving an aged, precision coordinate measuring machine, which is essential to the JASPER Program’s success. The selected option balances the risk to the machine with continuity of operations.

  9. Thermal Infrared and Visible to Near-Infrared Spectral Analysis of Chert and Amorphous Silica

    Science.gov (United States)

    McDowell, M. L.; Hamilton, V. E.; Cady, S. L.; Knauth, P.

    2009-03-01

    We look in detail at the thermal infrared and visible to near-infrared spectra of various forms of chert and amorphous silica and compare the spectral variations between samples with variations in physical and chemical characteristics.

  10. Jasper Sharp - mees, kes jättis varasema töö, et vaadata Jaapani filme / Jasper Sharp ; intervjueerinud Helen Merila

    Index Scriptorium Estoniae

    Sharp, Jasper, 1971-

    2011-01-01

    Euroopa kultuuripealinn Tallinn 2011 programmi osana ning koostöös Zipangu Fest'iga korraldatakse Tallinna Kinomajas 25.-28. aug.-ni Aasia sõltumatute filmide festival EVA - East via Asia. Festivali kuraator, veebisaidi Midnight Eye kaastoimetaja Jasper Sharp endast, festivalist, Jaapani sõltumatust kinost tänapäeval. Festivali kava

  11. Analysis of the JASPER Program Radial Shield Attenuation Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Slater, C.O.

    1993-01-01

    The results of the analysis of the JASPER Program Radial Shield Attenuation Experiment are presented. The experiment was performed in 1986 at the ORNL Tower Shielding Facility. It is the first of six experiments in this cooperative Japanese and American program in support of shielding designs for advanced sodium-cooled reactors. Six different shielding configurations and subconfigurations thereof were studied. The configurations were calculated with the DOT-IV two-dimensional discrete ordinates radiation transport computer code using the R-Z geometry option, a symmetric S{sub 12} quadrature (96 directions), and cross sections from ENDF/B versions IV and V in either a 51- or 61-group structure. Auxiliary codes were used to compute detector responses and prepare cross sections and source input for the DOT-IV calculations. Calculated detector responses were compared with measured responses and the agreement was good to excellent in many cases. However, the agreement for configurations having thick steel or B{sub 4}C regions or for some very large configurations was fair to poor. The disagreement was attributed to cross-section data, broad-group structure, or high background in the measurements. In particular, it is shown that two cross-section sets for ``B give very different results for neutron transmission through the thick B{sub 4}C regions used in one set of experimental configurations. Implications for design calculations are given.

  12. Frasnian-Famennian boundary near Jasper, Alberta, Canada

    Energy Technology Data Exchange (ETDEWEB)

    Geldsetzer, H.; Goodfellow, W.D.; McLaren, D.; Orchard, M.J.

    1985-01-01

    The extinction event at the Frasnian-Famennian boundary cannot be associated with a first-order event, whether impact, volcanic or other. However, data from Alberta and western Australia suggest a sudden flooding of cratonic areas by anoxic water as the immediate or second-order cause. In the Rocky Mountains near Jasper, Alberta abrupt sedimentological, geochemical and faunal changes occur between bioturbated dolomitic siltstones below and thinly laminated, very pyritic, argillaceous lime mudstones above. The siltstones which overlie thick subtidal sediments that infilled Middle Frasnian reef topography, were deposited in shallow, well oxygenated water and contain a Frasnian gigas Zone conodont fauna. In contrast, the overlying lime mudstones which pass upward into beds with Famennian triangularis Zone conodonts, represent deposition under strongly anoxic conditions; the contained pyrite has anomalously high delta/sup 34/S values suggesting prolonged bacterial reduction of sulfate to sulfide. The abrupt change to anoxic conditions could have been triggered by an ocean turn-over event as a result of which cratonic areas were flooded with anoxic water. This in turn would have caused a sharp reduction of the biomass and large-scale faunal extinctions.

  13. The chert quarrying and processing industry at the Piatra Tomii site, Romania

    Directory of Open Access Journals (Sweden)

    Otis Norman Crandell

    2015-03-01

    Full Text Available Fieldwalking surveys in 2007 and 2008 revealed a moderate sized settlement on Piatra Tomii Hill (Alba County, Romania which was considered of interest because of its location on top of a natural source of chert, and the large amount of chert artefacts found on the surface. In 2009 the site was excavated during which one of the objectives was to learn more about the chert mining and processing at the site. The ratio of artefact types and lack of use-wear suggests that not only was raw material being extracted at the site, but tools were also being produced locally before being exported. The 2009 excavations also revealed what appear to be the remains of pit quarrying and possibly fire cracked limestone and debris. These finds provide technical insight into potential chert extraction techniques utilised in the Late Chalcolithic and Early Bronze Age. As well, this is as yet the only reported settlement in the Transylvanian basin involved in chert extraction (either quarrying or mining. Given the settlement’s affluence, especially considering its relative isolation, it is likely that the chert industry here was important to communities in the vicinity. Indeed artefacts found at contemporary sites in the Mureș Valley appear to have been made from the same or a similar chert. This paper gives an introductions to the site, describes the artefacts and features found there and provides possible interpretations  regarding the processing and export industry, as well as the methods of extracting the raw material during this period.

  14. Treatment effects of the Jasper Jumper and the Bionator associated with fixed appliances.

    Science.gov (United States)

    Neves, Leniana Santos; Janson, Guilherme; Cançado, Rodrigo Hermont; de Lima, Karina Jerônimo Rodrigues Santiago; Fernandes, Thaís Maria Freire; Henriques, José Fernando Castanha

    2014-01-01

    The aim of this study was to evaluate the effects of Class II malocclusion treatment with the Jasper Jumper and the Bionator, associated with fixed appliances. The sample comprised 77 young individuals divided into 3 groups: Group 1 consisted of 25 patients treated with the Jasper Jumper appliance associated with fixed appliances for a mean period of 2.15 years; group 2 had 30 patients, treated with the Bionator and fixed appliances, for a mean treatment time of 3.92 years; and the control group included 22 subjects followed for a mean period of 2.13 years. The initial and final lateral cephalograms of the patients were evaluated. Intergroup comparison at the initial stage and of the treatment changes were performed by analysis of variance. Their effects consisted in a restrictive effect on the maxilla, a slight increase in anterior face height, retrusion and extrusion of the maxillary incisors, labial tipping and protrusion of the mandibular incisors in both groups and intrusion with the Jasper Jumper appliance, maxillary molar distalization with the Jasper Jumper, extrusion and mesialization of the mandibular molars, both appliances provided significant improvement of the maxillomandibular relationship, overjet, overbite and molar relationship. The effects of both appliances in class II malocclusion treatment are similar; however, treatment with the Jasper Jumper was shorter than with the Bionator.

  15. Densification of zirconia-hematite nanopowders

    NARCIS (Netherlands)

    Raming, T.P.; Winnubst, Aloysius J.A.; van Zyl, W.E.; Verweij, H.

    2003-01-01

    The densification of dual-phase yttria-doped tetragonal zirconia polycrystals (Y-TZP) and -Fe2O3 (hematite) composite powders is described. Different powder synthesis methods, different forms of dry compaction processes, and two sinter methods (pressureless sintering and sinterforging) were

  16. ["Homesickness and crime"--a contribution of Karl Jaspers to criminal psychology].

    Science.gov (United States)

    Bachhiesl, Sonja Maria

    2009-01-01

    Even a century after its first publication in "Archives of Criminology" (in German: Archiv für Kriminologie), the doctoral thesis of Karl Jaspers (1883-1969), which was newly edited in 1996, continues to be of interest. Although the crimes described by Jaspers, which took place in a rural area, do no longer occur in this form just as the rural culture itself has disappeared, this paper nevertheless contains reflections that may also be relevant for the interpretation of modern potentials of conflict and violence and crimes rooted therein. The former homesickness has developed into novel phenomena of uprooting. In both cases, problems of maladjustment are a contributing factor to crime motivation. Thus despite all terminological and methodological change, Jaspers' thesis is an example for the continuing relevance of certain subjects in criminological discourse.

  17. Laboratory Thermal Infrared and Visible to Near-Infrared Spectral Analysis of Chert

    Science.gov (United States)

    McDowell, M. L.; Hamilton, V. E.

    2007-12-01

    Though basaltic materials dominate the composition of the Martian surface, a material with a relatively high silica component in an area of Eos Chasma was reported by [1] from thermal infrared (TIR) data. The spectrum of the silica phase resembles quartz or chert, but with the existing information it is difficult to tell which phase best fits the observations. Though quartz, chert, and amorphous silica are chemically identical (SiO2), their physical differences (e.g., microstructures) result in different TIR spectral characteristics. Previous studies have analyzed a limited number of chert samples using emission infrared spectroscopy [2] and transmission infrared spectroscopy [3]. We continue these preliminary studies with an investigation aiming to more completely understand and document the variation in spectral character of cherts. This knowledge may help to identify the silica phase in Eos Chasma and any future discoveries. Our study includes a more extensive sampling of geologic chert in hand sample (>15 samples) with various sources, methods of formation, surface textures, and crystallinities. We analyzed their visible to near-infrared (VNIR) reflectance spectra, as well as spectral features in TIR emission spectra. We measured multiple locations on each sample to determine spectral homogeneity across the sample and between various orientations. Where possible, natural, cut, and recently fractured surfaces were measured. We compared the collected TIR spectra for similarities and differences in shape and spectral contrast within each sample and between samples that may relate to variations in the samples' structure (e.g. crystallinity, and surface texture). VNIR measurements show features indicative of non-silica phases and water that may be present in the cherts. [1] Hamilton, V.E. (2005) Eos Trans. AGU, Fall Meeting Suppl., Abstract P24A-08. [2] Michalski, J.R. (2005) PhD Diss., ASU, Tempe. [3] Long, D. G. et al. (2001) Canadian Archaeological Assoc., 33rd

  18. Equatorial origin for Lower Jurassic radiolarian chert in the Franciscan Complex, San Rafael Mountains, southern California

    Science.gov (United States)

    Hagstrum, J.T.; Murchey, B.L.; Bogar, R.S.

    1996-01-01

    Lower Jurassic radiolarian chert sampled at two localities in the San Rafael Mountains of southern California (???20 km north of Santa Barbara) contains four components of remanent magnetization. Components A, B???, and B are inferred to represent uplift, Miocene volcanism, and subduction/accretion overprint magnetizations, respectively. The fourth component (C), isolated between 580?? and 680??C, shows a magnetic polarity stratigraphy and is interpreted as a primary magnetization acquired by the chert during, or soon after, deposition. Both sequences are late Pliensbachian to middle Toarcian in age, and an average paleolatitude calculated from all tilt-corrected C components is 1?? ?? 3?? north or south. This result is consistent with deposition of the cherts beneath the equatorial zone of high biologic productivity and is similar to initial paleolatitudes determined for chert blocks in northern California and Mexico. This result supports our model in which deep-water Franciscan-type cherts were deposited on the Farallon plate as it moved eastward beneath the equatorial productivity high, were accreted to the continental margin at low paleolatitudes, and were subsequently distributed northward by strike-slip faulting associated with movements of the Kula, Farallon, and Pacific plates. Upper Cretaceous turbidites of the Cachuma Formation were sampled at Agua Caliente Canyon to determine a constraining paleolatitude for accretion of the Jurassic chert sequences. These apparently unaltered rocks, however, were found to be completely overprinted by the A component of magnetization. Similar in situ directions and demagnetization behaviors observed in samples of other Upper Cretaceous turbidite sequences in southern and Baja California imply that these rocks might also give unreliable results.

  19. Adsorption of aqueous silicate on hematite

    International Nuclear Information System (INIS)

    Taylor, P.; Ticknor, K.V.

    1997-08-01

    During radioisotope sorption studies, adsorption of silicate from synthetic groundwaters by synthetic hematite was observed. To further investigate this observation, the adsorption of silicate onto hematite (α-Fe 2 O 3 ) powder from a neutral, aqueous NaC1 solution (0.1 mol/dm 3 ), containing 2.56 x 10 -4 mol/dm 3 of Si added as Na 2 SiO 3 ·9H 2 O, was measured at ∼21 deg C. Equilibrium adsorption of silicate amounted to ∼1.93 μmol/m 2 (one Si(O,OH) 4 moiety per 86 A 2 ). It is important to take this adsorption into account when evaluating the ability of iron oxides to adsorb other species, especially anions, from groundwaters. Silicate adsorption is known to diminish the ability of iron oxides to adsorb other anions. (author)

  20. Spectral characteristics of banded iron formations in Singhbhum craton, eastern India: Implications for hematite deposits on Mars

    Directory of Open Access Journals (Sweden)

    Mahima Singh

    2016-11-01

    Full Text Available Banded iron formations (BIFs are major rock units having hematite layers intermittent with silica rich layers and formed by sedimentary processes during late Archean to mid Proterozoic time. In terrestrial environment, hematite deposits are mainly found associated with banded iron formations. The BIFs in Lake Superior (Canada and Carajas (Brazil have been studied by planetary scientists to trace the evolution of hematite deposits on Mars. Hematite deposits are extensively identified in Meridiani region on Mars. Many hypotheses have been proposed to decipher the mechanism for the formation of these deposits. On the basis of geomorphological and mineralogical studies, aqueous environment of deposition is found to be the most supportive mechanism for its secondary iron rich deposits. In the present study, we examined the spectral characteristics of banded iron formations of Joda and Daitari located in Singhbhum craton in eastern India to check its potentiality as an analog to the aqueous/marine environment on Mars. The prominent banding feature of banded iron formations is in the range of few millimeters to few centimeters in thickness. Fe rich bands are darker (gray in color compared to the light reddish jaspilitic chert bands. Thin quartz veins (<4 mm are occasionally observed in the hand-specimens of banded iron formations. Spectral investigations have been conducted in VIS/NIR region of electromagnetic spectrum in the laboratory conditions. Optimum absorption bands identified include 0.65, 0.86, 1.4 and 1.9 μm, in which 0.56 and 0.86 μm absorption bands are due to ferric iron and 1.4 and 1.9 μm bands are due to OH/H2O. To validate the mineralogical results obtained from VIS/NIR spectral radiometry, laser Raman and Fourier transform infrared spectroscopic techniques were utilized and the results were found to be similar. Goethite-hematite association in banded iron formation in Singhbhum craton suggests dehydration activity, which has

  1. 77 FR 50155 - Neal Smith National Wildlife Refuge, Jasper County, IA

    Science.gov (United States)

    2012-08-20

    ... DEPARTMENT OF THE INTERIOR Fish and Wildlife Service [FWS-R3-R-2012-N119; FXRS1265030000S3-123-FF03R06000] Neal Smith National Wildlife Refuge, Jasper County, IA AGENCY: Fish and Wildlife Service... 399, 9981 Pacific Street, Prairie City, IA 50228. In-Person Drop Off: You may drop off comments during...

  2. 78 FR 16286 - Neal Smith National Wildlife Refuge, Jasper County, IA; Final Comprehensive Conservation Plan and...

    Science.gov (United States)

    2013-03-14

    ...-FF03R06000] Neal Smith National Wildlife Refuge, Jasper County, IA; Final Comprehensive Conservation Plan and... the Environmental Assessment (EA) for Neal Smith National Wildlife Refuge (Refuge, NWR). In this final... . Include ``Neal Smith Final CCP'' in the subject line of the message. U.S. Mail: Neal Smith National...

  3. Weeping verse : Jasper Heywood's translation of Seneca's Troades and the politics of vicarious compassion

    NARCIS (Netherlands)

    Steenbergh, K.

    2017-01-01

    Jasper Heywood's Troas (1559) was the first English translation of one of Seneca's tragedies. Although Heywood's and later Tudor translations of Seneca's tragic corpus have predominantly been studied for their influence on Elizabethan revenge tragedy, recent criticism has focused on the way they

  4. Composition of the Rex Chert and associated rocks of the Permian Phosphoria Formation: Soda Springs area, SE Idaho

    Science.gov (United States)

    Hein, James R.; McIntyre, Brandie; Perkins, Robert B.; Piper, David Z.; Evans, James

    2002-01-01

    This study, one in a series, reports bulk chemical and mineralogical compositions, as well as petrographic and outcrop descriptions of rocks collected from three measured outcrop sections of the Rex Chert member of the Phosphoria Formation in SE Idaho. The three measured sections were chosen from ten outcrops of Rex Chert that were described in the field. The Rex Chert overlies the Meade Peak Phosphatic Shale Member of the Phosphoria Formation, the source of phosphate ore in the region. Rex Chert removed as overburden comprises part of the material disposed in waste-rock piles during phosphate mining. It has been proposed that the chert be used to cap and isolate waste piles, thereby inhibiting the leaching of potentially toxic elements into the environment. It is also used to surface roads in the mining district. The rock samples studied here constitute a set of individual chert beds that are representative of each stratigraphic section sampled. The informally named cherty shale member that overlies the Rex Chert in measured section 1 was also described and sampled. The upper Meade Peak and the transition zone to the Rex Chert were described and sampled in section 7. The cherts are predominantly spicularite composed of granular and mosaic quartz, and sponge spicules, with various but minor amounts of other fossils and detrital grains. The cherty shale member and transition rocks between the Meade Peak and Rex Chert are siliceous siltstones and argillaceous cherts with ghosts of sponge spicules and somewhat more detrital grains than the chert. The overwhelmingly dominant mineral is quartz, although carbonate beds are rare in each section and are composed predominantly of calcite and dolomite in addition to quartz. Feldspar, mica, clay minerals, calcite, dolomite, and carbonate fluorapatite are minor to trace minerals in the chert. The mean concentrations of oxides and elements in the Rex Chert and the cherty shale member are dominated by SiO2, which averages 94

  5. Characterization of hematite nanoparticles synthesized via two different pathways

    Science.gov (United States)

    Das, Soumya; Hendry, M. Jim

    2014-08-01

    Hematite is one of the most common and thermodynamically stable iron oxides found in both natural and anthropogenic systems. Owing to its ubiquity, stability, moderate specific surface area, and ability to sequester metals and metalloids from aquatic systems, it has been the subject of a large number of adsorption studies published during the past few decades. Although preparation techniques are known to affect the surface morphology of hematite nanoparticles, the effects of aging under environmentally relevant conditions have yet to be tested with respect to surface morphology, surface area, and adsorptive capacity. We prepared hematite via two different pathways and aged it under highly alkaline conditions encountered in many mill tailings settings. Crystal habits and morphologies of the hematite nanoparticles were analyzed via scanning electron microscopy and transmission electron microscopy. X-ray diffraction, Raman spectroscopy, and Brunauer-Emmett-Teller surface area analyses were also conducted on the hematite nanoparticles before and after aging. The hematite synthesized via an Fe(III) salt solution (average particle size 37 nm) was morphologically and structurally different from the hematite synthesized via ferrihydrite aging (average particle size 144 nm). Overall, our data demonstrate that the crystallinity of hematite produced via ferrihydrite transformation is susceptible to morphological alterations/modifications. In contrast, the hematite formed via hydrolysis of an Fe(III) salt solution remains very stable in terms of structure, size, and morphology even under extreme experimental conditions.

  6. Thickness Dependent on Photocatalytic Activity of Hematite Thin Films

    Directory of Open Access Journals (Sweden)

    Yen-Hua Chen

    2012-01-01

    Full Text Available Hematite (Fe2O3 thin films with different thicknesses are fabricated by the rf magnetron sputtering deposition. The effects of film thicknesses on the photocatalytic activity of hematite films have been investigated. Hematite films possess a polycrystalline hexagonal structure, and the band gap decreases with an increase of film thickness. Moreover, all hematite films exhibit good photocatalytic ability under visible-light irradiation; the photocatalytic activity of hematite films increases with the increasing film thickness. This is because the hematite film with a thicker thickness has a rougher surface, providing more reaction sites for photocatalysis. Another reason is a lower band gap of a hematite film would generate more electron-hole pairs under visible-light illumination to enhance photocatalytic efficiency. Experimental data are well fitted with Langmuir-Hinshelwood kinetic model. The photocatalytic rate constant of hematite films ranges from 0.052 to 0.068 min-1. This suggests that the hematite film is a superior photocatalyst under visible-light irradiation.

  7. Magnetic and structural properties of ferrihydrite/hematite nanocomposites

    International Nuclear Information System (INIS)

    Pariona, N.; Camacho-Aguilar, K.I.; Ramos-González, R.; Martinez, Arturo I.; Herrera-Trejo, M.; Baggio-Saitovitch, E.

    2016-01-01

    A rich variety of ferrihydrite/hematite nanocomposites (NCs) with specific size, composition and properties were obtained in transformation reactions of 2-line ferrihydrite. Transmission electron microscopy (TEM) observations showed that the NCs consist of clusters of strongly aggregated nanoparticles (NPs) similarly to a “plum pudding”, where hematite NPs “raisins” are surrounded by ferrihydrite “pudding”. Magnetic measurements of the NCs correlate very well with TEM results; i.e., higher coercive fields correspond to greater hematite crystallite size. First order reversal curve (FORC) measurements were used for the characterization of the magnetic components of the NCs. FORC diagrams revealed that the NCs prepared at short times are composed by single domains with low coercivity, and NCs prepared at times larger than 60 min exhibited elongated distribution along the Hc axis. It suggested that these samples consist of mixtures of different kinds of hematite particles, ones with low coercivity and others with coercivity greater than 600 Oe. For NCs prepared at times larger than 60 min, Mossbauer spectroscopy revealed the presence of two sextets, which one was assigned to fine hematite particles and other to hematite particles with hyperfine parameters near to bulk hematite. The correlation of the structural and magnetic properties of the ferrihydrite/hematite NCs revealed important characteristics of these materials which have not been reported elsewhere. - Highlights: • Ferrihydrite/hematite nanocomposites were prepared. • The “plum pudding” morphology of the ferrihydrite/hematite nanocomposites was found. • The FORC diagrams of ferrihydrite/hematite nanocomposites have been measured.

  8. Magnetic and structural properties of ferrihydrite/hematite nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Pariona, N.; Camacho-Aguilar, K.I.; Ramos-González, R. [Center for Research and Advanced Studies of the National Polytechnic Institute, Cinvestav-Saltillo, Av. Industria Metalúrgica 1062, Parque Industrial Ramos Arizpe, Coahuila 25900 (Mexico); Martinez, Arturo I., E-mail: mtz.art@gmail.com [Center for Research and Advanced Studies of the National Polytechnic Institute, Cinvestav-Saltillo, Av. Industria Metalúrgica 1062, Parque Industrial Ramos Arizpe, Coahuila 25900 (Mexico); Herrera-Trejo, M. [Center for Research and Advanced Studies of the National Polytechnic Institute, Cinvestav-Saltillo, Av. Industria Metalúrgica 1062, Parque Industrial Ramos Arizpe, Coahuila 25900 (Mexico); Baggio-Saitovitch, E. [Centro Brasileiro de Pesquisas Físicas, Río de Janeiro 22290-180 (Brazil)

    2016-05-15

    A rich variety of ferrihydrite/hematite nanocomposites (NCs) with specific size, composition and properties were obtained in transformation reactions of 2-line ferrihydrite. Transmission electron microscopy (TEM) observations showed that the NCs consist of clusters of strongly aggregated nanoparticles (NPs) similarly to a “plum pudding”, where hematite NPs “raisins” are surrounded by ferrihydrite “pudding”. Magnetic measurements of the NCs correlate very well with TEM results; i.e., higher coercive fields correspond to greater hematite crystallite size. First order reversal curve (FORC) measurements were used for the characterization of the magnetic components of the NCs. FORC diagrams revealed that the NCs prepared at short times are composed by single domains with low coercivity, and NCs prepared at times larger than 60 min exhibited elongated distribution along the Hc axis. It suggested that these samples consist of mixtures of different kinds of hematite particles, ones with low coercivity and others with coercivity greater than 600 Oe. For NCs prepared at times larger than 60 min, Mossbauer spectroscopy revealed the presence of two sextets, which one was assigned to fine hematite particles and other to hematite particles with hyperfine parameters near to bulk hematite. The correlation of the structural and magnetic properties of the ferrihydrite/hematite NCs revealed important characteristics of these materials which have not been reported elsewhere. - Highlights: • Ferrihydrite/hematite nanocomposites were prepared. • The “plum pudding” morphology of the ferrihydrite/hematite nanocomposites was found. • The FORC diagrams of ferrihydrite/hematite nanocomposites have been measured.

  9. Hematite nuclear fuel cycle facility decommissioning

    International Nuclear Information System (INIS)

    Hayes, K.

    2004-01-01

    Westinghouse Electric Company LLC ('Westinghouse') acquired a nuclear fuel processing plant at Hematite, Missouri ('Hematite', the 'Facility', or the 'Plant') in April 2000. The plant has subsequently been closed, and its operations have been relocated to a newer, larger facility. Westinghouse has announced plans to complete its clean-up, decommissioning, and license retirement in a safe, socially responsible, and environmentally sound manner as required by internal policies, as well as those of its parent company, British Nuclear Fuels plc. ('BNFL'). Preliminary investigations have revealed the presence of environmental contamination in various areas of the facility and grounds, including both radioactive contamination and various other substances related to the nuclear fuel processing operations. The disparity in regulatory requirements for radiological and nonradiological contaminants, the variety of historic and recent operations, and the number of previous owners working under various contractual arrangements for both governmental and private concerns has resulted in a complex project. This paper discusses Westinghouse's efforts to develop and implement a comprehensive decontamination and decommissioning (D and D) strategy for the facility and grounds. (author)

  10. Thermoluminescence dating of burnt cherts from the Alice Boer site (Brazil)

    International Nuclear Information System (INIS)

    Beltrao, M. da C.M.C.; Enriquez, C.R.; Danon, J.; Zuleta, E.

    1983-01-01

    More than 40 culturally burnt cherts from the Alice Boer site near Rio Claro, Sao Paulo State, have been studied by thermoluminescence (TL). Nine of these were found to be sufficiently heated by early man to reset the TL clock to zero and thereby be suitable for TL dating. These cherts define, for the upper half of the uppermost cultural layer (layer III), a time scale for the presence of man from 2,220 to 11,000 years. This time range is in essential agreement with the geological-paleoclimatological age estimate for the end of deposition of this layer, as well as with radiocarbon dates. In particular, it lends support to a radiocarbon age of 14,000 BP for a deeper level. The overall geochronologic results are not in contradiction with earlier statements that the deepest cultural layer (layer V) at Alice Boer might have been deposited at least 20,000 years ago. (Author) [pt

  11. Trace element mapping of two Pyrenean chert deposits (SW Europe) by PIXE

    Energy Technology Data Exchange (ETDEWEB)

    Sánchez de la Torre, Marta, E-mail: marta.sanchez-de-la-torre@u-bordeaux-montaigne.fr [IRAMAT-CRP2A (UMR 5060), CNRS/Université Bordeaux Montaigne, Maison de l’Archéologie, Esplanade des Antilles, 33607 Pessac Cedex (France); SERP-Universitat de Barcelona, Montalegre St 6-8, 08001 Barcelona (Spain); Angyal, Anikó; Kertész, Zsófia [MTA Atomki, Institute for Nuclear Research, Hungarian Academy of Sciences, H-4026 Debrecen (Hungary); Dubernet, Stéphan; Le Bourdonnec, François-Xavier [IRAMAT-CRP2A (UMR 5060), CNRS/Université Bordeaux Montaigne, Maison de l’Archéologie, Esplanade des Antilles, 33607 Pessac Cedex (France); Csedreki, László; Furu, Enikő; Papp, Enikő; Szoboszlai, Zoltán; Szikszai, Zita [MTA Atomki, Institute for Nuclear Research, Hungarian Academy of Sciences, H-4026 Debrecen (Hungary)

    2017-06-01

    The geochemical character of two chert formations from the Pyrenean mountain range (SW Europe) was established by PIXE analyses. While it was not possible to distinguish the formations through reference to major and minor elements, some variations were revealed at the trace elemental level. In order to determine if these elements are associated with the Si matrix or to the contents of a specific inclusion, elemental maps were acquired and the elemental composition of the identified inclusions were also determined. As a result, Sr, Ni and Zn are better represented in Montgaillard samples while Y, Hf, W and Zr are typical of Montsaunès cherts. Thanks to elemental maps it has been possible to determine that most of these characteristic elements are usually related to a specific inclusion content.

  12. Detecting human mobility in the Pyrenees through the analysis of chert tools during the Upper Palaeolithic

    Directory of Open Access Journals (Sweden)

    Marta Sánchez de la Torre

    2014-03-01

    Full Text Available The purpose of this paper is to present the preliminary results of PhD research focused on hunter-gatherer groups that occupied the Central and Eastern Pyrenees during the Magdalenian period. This research aims to improve the knowledge we have about those Magdalenian groups, specifically concerning their lithic procurement strategies. The core of the study is based on the lithic tools collected from two archaeological sites - Alonsé Cave and Forcas I Shelter, both in Huesca, Spain-, and in particular those made from chert, because they are both a spatial and a cultural marker at the same time. These cherts have been studied using petroarchaeological methods, and as a result, it has been possible to detect the type of procurement strategies carried out and to guess the relation existing between those human groups and their environment, especially in what refers to mobility strategies.

  13. Preschool Deployment of Evidence-Based Social Communication Intervention: JASPER in the Classroom.

    Science.gov (United States)

    Chang, Ya-Chih; Shire, Stephanie Y; Shih, Wendy; Gelfand, Carolyn; Kasari, Connie

    2016-06-01

    Few research-developed early intervention models have been deployed to and tested in real world preschool programs. In this study, teaching staff implemented a social communication modularized intervention, JASPER, in their daily program. Sixty-six preschool children with autism in twelve classrooms (12 teachers) were randomized to receive immediate JASPER training (IT) or were waitlisted (WL) for 3 months with a 1-month follow up. Measures of core deficits (initiations of joint engagement, joint attention gestures and language, play skills) and standardized cognitive measures were improved for IT over WL children. IT teachers achieved and maintained high fidelity. Teachers can implement evidence-based interventions with significant improvements in core deficits of their children with ASD.

  14. Mapping the Metal Uptake in Plants from Jasper Ridge Biological Preserve - Oral Presentation

    Energy Technology Data Exchange (ETDEWEB)

    Lo, Allison [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-08-24

    Serpentine soil originates in the Earth’s mantle and contains high concentrations of potentially toxic transition metals. Although serpentine soil limits plant growth, endemic and adapted plants at Jasper Ridge Biological Preserve, located behind SLAC National Accelerator Laboratory, can tolerate these conditions. Serpentine soil and seeds belonging to native California and invasive plants were collected at Jasper Ridge. The seeds were grown hydroponically and on serpentine and potting soil to examine the uptake and distribution of ions in the roots and shoots using synchrotron micro-focused X-ray fluorescence spectroscopy. The results were used to determine differences between serpentinetolerant plants. Rye grown on potting soil was enriched in Ni, Fe, Mn, and Cr compared to purple needlegrass grown on serpentine soil. Serpentine vegetation equally suppressed the uptake of Mn, Ni, and Fe in the roots and shoots. The uptake of Ca and Mg affected the uptake of other elements such as K, S, and P.

  15. Magnetic microsperules in Permian and Triassic bedded chert from Southwest Japan

    OpenAIRE

    Iwahashi,Junko; Yoshida,Masaru; Miono,Shigeyoshi; Santosh,Geetha; Santosh,M.

    1991-01-01

    Magnetic microspherules collected from the Permian and Triassic bedded cherts in Southwest Japan were studied. The size range, as estimated from 801 microspherules, vary from 3 to 100μm, with a peak size distribution between 10-20μm. Three broad shapes are recognized : spherical-, drop- and rocket-shaped, all categories including hollow particles. The surface textures as studied from scanning electron microscope show five dominant varieties : random mosaic, dendritic mosaic, feather crystal, ...

  16. Karl Jaspers on the disease entity: Kantian ideas and Weberian ideal types.

    Science.gov (United States)

    Walker, Chris

    2014-09-01

    Jaspers' nosology is indebted to Immanuel Kant's theory of knowledge. He drew the distinction of form and content from the Transcendental Analytic of Kant's Critique of Pure Reason. The distinction is universal to all knowledge, including psychopathology. Individual experience is constituted by a form or category of the Understanding to give a determinate or knowable object classified into the generic type of a real disease entity. The application of form and content is limited by the boundaries of experience. Beyond this boundary are wholes whose conception requires Ideas of reason drawn from the Transcendental Dialectic. Wholes are regulated by Ideas of reason to give an object or schema of the Idea collected into ideal types of an ideal typical disease entity. Jaspers drew ideal types from Max Weber's social theory. He anticipated that, as knowledge advanced, ideal typical disease entities would become real disease entities. By 1920, this had been the destiny of general paralysis as knowledge of its neuropathology, serology and microbiology emerged. As he presented the final edition of General Psychopathology in 1946, Jaspers was anticipating the transition of schizophrenia from ideal typical to real disease entity. Almost 70 years later, with knowledge of its aetiology still unclear, schizophrenia remains marooned as an ideal typical disease entity - still awaiting that crucial advance! © The Author(s) 2014.

  17. Local structural order in nanostructured hematite

    International Nuclear Information System (INIS)

    Florez, J. M.; Mazo-Zuluaga, J.; Restrepo, J.

    2005-01-01

    Nanostructured α-Fe 2 O 3 powders were prepared by high-energy ball milling. The milling process spans grinding times from 30 min to 24 h. The as-milled samples were characterized by means of 57 Fe Moessbauer spectrometry, Rietveld analysis of X-ray diffraction data and particle size analysis. The obtained results evidence the presence of disordered hematite characterized by a hyperfine field distribution with a well-behaved dependence on the mean crystallite size for which the mean hyperfine field decreases asymptotically as the grain size decreases. A new relationship is proposed in order to describe such behavior. Finally the presence of superparamagnetic grains, the occurrence of a partial topotactic phase transformation into a spinel phase and tool induced contamination are also presented and discussed.

  18. Local structural order in nanostructured hematite

    Energy Technology Data Exchange (ETDEWEB)

    Florez, J. M.; Mazo-Zuluaga, J.; Restrepo, J., E-mail: jrestre@fisica.udea.edu.co [Universidad de Antioquia, Grupo de Estado Solido, Instituto de Fisica (Colombia)

    2005-09-15

    Nanostructured {alpha}-Fe{sub 2}O{sub 3} powders were prepared by high-energy ball milling. The milling process spans grinding times from 30 min to 24 h. The as-milled samples were characterized by means of {sup 57}Fe Moessbauer spectrometry, Rietveld analysis of X-ray diffraction data and particle size analysis. The obtained results evidence the presence of disordered hematite characterized by a hyperfine field distribution with a well-behaved dependence on the mean crystallite size for which the mean hyperfine field decreases asymptotically as the grain size decreases. A new relationship is proposed in order to describe such behavior. Finally the presence of superparamagnetic grains, the occurrence of a partial topotactic phase transformation into a spinel phase and tool induced contamination are also presented and discussed.

  19. Boron adsorption on hematite and clinoptilolite

    International Nuclear Information System (INIS)

    Gainer, G.M.

    1993-01-01

    This thesis describes experiments performed to determine the suitability of boron as a potential reactive tracer for use in saturated-zone C-well reactive tracer studies for the Yucca Mountain Project (YMP). Experiments were performed to identify the prevalent sorption mechanism of boron and to determine adsorption of boron on hematite and clinoptilolite as a function of pH. These minerals are present in the Yucca Mountain tuff in which the C-well studies will be conducted. Evaluation of this sorption mechanism was done by determining the equilibration time of boron-mineral suspensions, by measuring changes in equilibrium to titrations, and by measuring electrophoretic mobility. Experiments were performed with the minerals suspended in NaCl electrolytes of concentrations ranging from 0.1 N NaCl to 0.001 N NaCl. Experimentalconditions included pH values between 3 and 12 and temperature of about 38 degrees C

  20. Spin orientation in solid solution hematite-ilmenite

    DEFF Research Database (Denmark)

    Brok, Erik; Frandsen, Cathrine; Lefmann, Kim

    2017-01-01

    temperature range below the Néel temperature and does not depend systematically on Ti-content. The results indicate that the out-of-plane spin component is an intrinsic feature of hematite itself, with an origin not yet fully understood, but consistent with group theory. This represents a major shift...... spectroscopy. The usually assumed magnetic structure of hematite within this temperature range is antiferromagnetic with the spins confined to the basal plane of the hexagonal structure; however, an out-of-plane spin component is allowed by the symmetry of the system and has been observed in recent studies......The spin orientation in synthetic hematite-ilmenite samples and in a sample of natural hematite was studied from room temperature to above the antiferromagnetic-paramagnetic phase transition (the Néel temperature; TN ≈ 600–950 K) by neutron powder diffraction and at room temperature by Mössbauer...

  1. Magnetic clusters in ilmenite-hematite solid solutions

    DEFF Research Database (Denmark)

    Frandsen, Cathrine; Burton, B. P.; Rasmussen, Helge Kildahl

    2010-01-01

    We report the use of high-field 57Fe Mössbauer spectroscopy to resolve the magnetic ordering of ilmenite-hematite [xFeTiO3−(1−x)Fe2O3] solid solutions with x>0.5. We find that nanometer-sized hematite clusters exist within an ilmenite-like matrix. Although both phases are antiferromagnetically...

  2. The rheological behaviour of fracture-filling cherts: example of Barite Valley dikes, Barberton Greenstone Belt, South Africa

    Science.gov (United States)

    Ledevin, M.; Arndt, N.; Davaille, A.; Ledevin, R.; Simionovici, A.

    2015-02-01

    In the Barberton Greenstone Belt, South Africa, a 100-250 m thick complex of carbonaceous chert dikes marks the transition from the Mendon Formation to the Mapepe Formation (3260 Ma). The sub-vertical- to vertical position of the fractures, the abundance of highly shattered zones with poorly rotated angular fragments and common jigsaw fit, radial structures, and multiple injection features point to repetitive hydraulic fracturing that released overpressured fluids trapped within the shallow crust. The chemical and isotopic compositions of the chert favour a model whereby seawater-derived fluids circulated at low temperature (clay-sized, rounded particles of silica, carbonaceous matter and minor clay minerals, all suspended in a siliceous colloidal solution. The dike geometry and characteristics of the slurry concur on that the chert was viscoelastic, and most probably thixotropic at the time of injection: the penetration of black chert into extremely fine fractures is evidence for low viscosity at the time of injection and the suspension of large country rock fragments in the chert matrix provides evidence of high viscosity soon thereafter. We explain the rheology by the particulate and colloidal structure of the slurry, and by the characteristic of silica suspensions to form cohesive 3-D networks through gelation. Our results provide valuable information about the compositions, physical characteristics and rheological properties of the fluids that circulated through Archean volcano-sedimentary sequences, which is an additional step to understand conditions on the floor of Archean oceans, the habitat of early life.

  3. Incorporation of Uranium into Hematite during Crystallization from Ferrihydrite

    Science.gov (United States)

    2014-01-01

    Ferrihydrite was exposed to U(VI)-containing cement leachate (pH 10.5) and aged to induce crystallization of hematite. A combination of chemical extractions, TEM, and XAS techniques provided the first evidence that adsorbed U(VI) (≈3000 ppm) was incorporated into hematite during ferrihydrite aggregation and the early stages of crystallization, with continued uptake occurring during hematite ripening. Analysis of EXAFS and XANES data indicated that the U(VI) was incorporated into a distorted, octahedrally coordinated site replacing Fe(III). Fitting of the EXAFS showed the uranyl bonds lengthened from 1.81 to 1.87 Å, in contrast to previous studies that have suggested that the uranyl bond is lost altogether upon incorporation into hematite. The results of this study both provide a new mechanistic understanding of uranium incorporation into hematite and define the nature of the bonding environment of uranium within the mineral structure. Immobilization of U(VI) by incorporation into hematite has clear and important implications for limiting uranium migration in natural and engineered environments. PMID:24580024

  4. The transformation of ferrihydrite into goethite or hematite, revisited

    International Nuclear Information System (INIS)

    Cudennec, Yannick; Lecerf, Andre

    2006-01-01

    During the oxidation of iron, poorly crystallized phases are firstly formed: 2- and 6-line ferrihydrite, which presents for the last phase, a similarity with wustite FeO but also with hematite α-Fe 2 O 3 . Crystallization increases with time and the solid phase obtained is dependent on temperature and pH. Obviously, high temperature favours the formation of the oxide hematite α-Fe 2 O 3 . As for the pH factor, it is more complicated. Low and high values of pH (2-5 and 10-14) favour the formation of goethite α-FeOOH, while obtaining hematite is favoured at neutral pH (values around 7). Goethite or hematite are obtained either through a dissolution-crystallization process or in the solid state, through a topotactic transformation. Given the structural relationships observed between ferrihydrite and wustite and hematite, it is allowed to think that a structural continuity could exist between wustite Fe (1- x ) O and hematite via ferrihydrite

  5. Bioavailability of nanoparticulate hematite to Arabidopsis thaliana

    International Nuclear Information System (INIS)

    Marusenko, Yevgeniy; Shipp, Jessie; Hamilton, George A.; Morgan, Jennifer L.L.; Keebaugh, Michael; Hill, Hansina; Dutta, Arnab; Zhuo, Xiaoding; Upadhyay, Nabin; Hutchings, James; Herckes, Pierre; Anbar, Ariel D.; Shock, Everett; Hartnett, Hilairy E.

    2013-01-01

    The environmental effects and bioavailability of nanoparticulate iron (Fe) to plants are currently unknown. Here, plant bioavailability of synthesized hematite Fe nanoparticles was evaluated using Arabidopsis thaliana (A. thaliana) as a model. Over 56-days of growing wild-type A. thaliana, the nanoparticle-Fe and no-Fe treatments had lower plant biomass, lower chlorophyll concentrations, and lower internal Fe concentrations than the Fe-treatment. Results for the no-Fe and nanoparticle-Fe treatments were consistently similar throughout the experiment. These results suggest that nanoparticles (mean diameter 40.9 nm, range 22.3–67.0 nm) were not taken up and therefore not bioavailable to A. thaliana. Over 14-days growing wild-type and transgenic (Type I/II proton pump overexpression) A. thaliana, the Type I plant grew more than the wild-type in the nanoparticle-Fe treatment, suggesting Type I plants cope better with Fe limitation; however, the nanoparticle-Fe and no-Fe treatments had similar growth for all plant types. -- Highlights: ► Iron nanoparticles were synthesized and assessed for bioavailability to Arabidopsis. ► Arabidopsis grew better in the presence of EDTA-bound iron than nanoparticulate iron. ► Arabidopsis grew the same in the presence of nanoparticulate iron compared to no iron. -- Synthesized iron nanoparticles were not bioavailable to Arabidopsis thaliana in agar nutrient media

  6. [Resilience and Spirituality Considered from Viewpoint of Existential Philosophy of Karl Jaspers].

    Science.gov (United States)

    Kato, Satoshi

    2015-01-01

    After publishing "General Psychopathology" in 1913, Jaspers turned his attention to serious philosophical contemplation. Using the term grenzsituation (limit situation) as a key concept, he first presented a framework to shed light on the pathology of both individuals and groups, and this led on to include the perspective of resilience. He then used three more key concepts, transzendenz (transcendence), chiffer (cipher), and unverstädliche (unintelligible) to offer a framework to focus on the possibilities of human existence. In the field of medicine, this is useful to support a spiritual approach which is discussed in palliative treatment. The philosophy developed by Jaspers can be considered as indicating a practical form of guidance for people to find self-support from a limit situation where they have lost their own support, and finally, come to a degree of mutual acceptance. Mutual acceptance is made possible at the level of ciphers, in which specific meaning remains undefined, by directing both the self and the other toward a state of "transcendence". Nowadays there is a trend for those chaplains involved in spiritual care from a specialist point of view to be trained to effectively transcend any difference in religious belief. As a basic premise, the author considers there is a need to once again return to a state before the start of individual religions, and stand on a cross-sectional ground level, an area which could be regarded as common to all religions. When conducting such a task, in the author's view, the restrained spirituality that Jaspers expounded is thought-provoking.

  7. Flood-inundation maps for the Patoka River in and near Jasper, southwestern Indiana

    Science.gov (United States)

    Fowler, Kathleen K.

    2018-01-23

    Digital flood-inundation maps for a 9.5-mile reach of the Patoka River in and near the city of Jasper, southwestern Indiana (Ind.), from the streamgage near County Road North 175 East, downstream to State Road 162, were created by the U.S. Geological Survey (USGS) in cooperation with the Indiana Department of Transportation. The flood-inundation maps, which can be accessed through the USGS Flood Inundation Mapping Science web site at https://water.usgs.gov/osw/flood_inundation/, depict estimates of the areal extent and depth of flooding corresponding to selected water levels (stages) at the USGS streamgage Patoka River at Jasper, Ind. (station number 03375500). The Patoka streamgage is located at the upstream end of the 9.5-mile river reach. Near-real-time stages at this streamgage may be obtained from the USGS National Water Information System at https://waterdata.usgs.gov/ or the National Weather Service Advanced Hydrologic Prediction Service at http://water.weather.gov/ahps/, although flood forecasts and stages for action and minor, moderate, and major flood stages are not currently (2017) available at this site (JPRI3).Flood profiles were computed for the stream reach by means of a one-dimensional step-backwater model. The hydraulic model was calibrated by using the most current stage-discharge relation at the Patoka River at Jasper, Ind., streamgage and the documented high-water marks from the flood of April 30, 2017. The calibrated hydraulic model was then used to compute five water-surface profiles for flood stages referenced to the streamgage datum ranging from 15 feet (ft), or near bankfull, to 19 ft. The simulated water-surface profiles were then combined with a geographic information system digital elevation model (derived from light detection and ranging [lidar] data having a 0.98 ft vertical accuracy and 4.9 ft horizontal resolution) to delineate the area flooded at each water level.The availability of these flood-inundation maps, along with real

  8. The Rhynie Chert, Scotland, and the search for life on Mars.

    Science.gov (United States)

    Preston, Louisa J; Genge, Matthew J

    2010-06-01

    Knowledge of ancient terrestrial hydrothermal systems-how they preserve biological information and how this information can be detected-is important in unraveling the history of life on Earth and, perhaps, that of extinct life on Mars. The Rhynie Chert in Scotland was originally deposited as siliceous sinter from Early Devonian hot springs and contains exceptionally well-preserved fossils of some of the earliest plants and animals to colonize the land. The aim of this study was to identify biomolecules within the samples through Fourier transform infrared (FTIR) spectroscopy and aid current techniques in identification of ancient hot spring deposits and their biological components on Mars. Floral and faunal fossils within the Rhynie Chert are commonly known; but new, FTIR spectroscopic analyses of these fossils has allowed for identification of biomolecules such as aliphatic hydrocarbons and OH molecules that are potentially derived from the fossilized biota and their environment. Gas chromatograph-mass spectrometer (GCMS) data were used to identify n-alkanes; however, this alone cannot be related to the samples' biota. Silicified microfossils are more resistant to weathering or dissolution, which renders them more readily preservable over time. This is of particular interest in astropaleontological research, considering the similarities in the early evolution of Mars and Earth.

  9. Far-travelled permian chert of the North Fork terrane, Klamath mountains, California

    Science.gov (United States)

    Mankinen, E.A.; Irwin, W.P.; Blome, C.D.

    1996-01-01

    Permian chert in the North Fork terrane and correlative rocks of the Klamath Mountains province has a remanent magnetization that is prefolding and presumably primary. Paleomagnetic results indicate that the chert formed at a paleolatitude of 8.6?? ?? 2.5?? but in which hemisphere remains uncertain. This finding requires that these rocks have undergone at least 8.6?? ?? 4.4?? of northward transport relative to Permian North America since their deposition. Paleontological evidence suggests that the Permian limestone of the Eastern Klamath terrane originated thousands of kilometers distant from North America. The limestone of the North Fork terrane may have formed at a similar or even greater distance as suggested by its faunal affinity to the Eastern Klamath terrane and more westerly position. Available evidence indicates that convergence of the North Fork and composite Central Metamorphic-Eastern Klamath terranes occurred during Triassic or Early Jurassic time and that their joining together was a Middle Jurassic event. Primary and secondary magnetizations indicate that the new composite terrane containing these and other rocks of the Western Paleozoic and Triassic belt behaved as a single rigid block that has been latitudinally concordant with the North American craton since Middle Jurassic time.

  10. Electro-oxidation of water on hematite: Effects of surface termination and oxygen vacancies investigated by first-principles

    DEFF Research Database (Denmark)

    Hellman, Anders; Iandolo, Beniamino; Wickman, Bjorn

    2015-01-01

    The oxygen evolution reaction on hydroxyl- and oxygen-terminated hematite was investigated using first-principle calculations within a theoretical electrochemical framework. Both pristine hematite and hematite containing oxygen vacancies were considered. The onset potential was determined to be 1...... on hematite occurs on the oxygen-terminated hematite, containing oxygen vacancies. (C) 2015 Elsevier B.V. All rights reserved....

  11. Rare earth, major, and trace element composition of Monterey and DSDP chert and associated host sediment: Assessing the influence of chemical fractionation during diagenesis

    Science.gov (United States)

    Murray, R.W.; Buchholtz ten Brink, Marilyn R.; Gerlach, David C.; Russ III, G. Price; Jones, David L.

    1992-01-01

    Chert and associated host sediments from Monterey Formation and Deep Sea Drilling Project (DSDP) sequences were analyzed in order to assess chemical behavior during diagenesis of biogenic sediments. The primary compositional contrast between chert and host sediment is a greater absolute SiO2 concentration in chert, often with final SiO2 ≥ 98 wt%. This contrast in SiO2 (and SiAl">SiAl) potentially reflects precursor sediment heterogeneity, diagenetic chemical fractionation, or both. SiO2 concentrations and SiAl">SiAl ratios in chert are far greater than in modern siliceous oozes, however and often exceed values in acid-cleaned diatom tests. Compositional contrasts between chert and host sediment are also orders-of-magnitude greater than between multiple samples of the host sediment. Calculations based on the initial composition of adjacent host, observed porosity reductions from host to chert and a postulated influx of pure SiO2, construct a chert composition which is essentially identical to observed SiO2 values in chert. Thus, precursor heterogeneity does not seem to be the dominant factor influencing the current chert composition for the key elements of interest. In order to assess the extent of chemical fractionation during diagenesis, we approximate the precursor composition by analyzing host sediments adjacent to the chert.The SiO2 concentration contrast seems caused by biogenic SiO2 dissolution and transport from the local adjacent host sediment and subsequent SiO2reprecipitation in the chert. Along with SiO2, other elements are often added (with respect to Al) to Monterey and DSDP chert during silicification, although absolute concentrations decrease. The two Monterey quartz chert nodules investigated, in contrast to the opal-CT and quartz chert lenses, formed primarily by extreme removal of carbonate and phosphate, thereby increasing relative SiO2 concentrations. DSDP chert formed by both carbonate/phosphate dissolution and SiO2 addition from

  12. Surface Potential of Polycrystalline Hematite in Aqueous Medium

    Directory of Open Access Journals (Sweden)

    Tajana Preočanin

    2011-01-01

    Full Text Available The surface potential of polycrystalline hematite in aqueous sodium perchlorate environment as a function of pH was examined. Surface potential of hematite was obtained from measured electrode potential of a nonporous polycrystalline hematite electrode. Acidic solution was titrated with base, and the backward titration with acid was performed. Substantial hysteresis was obtained which enabled location of the point of zero potential and equilibrium values of surface potentials. The theoretical interpretation of the equilibrium data was performed by applying the surface complexation model and the thermodynamic equilibrium constants for the first and the second step of surface protonation was obtained as logK1∘=11.3;logK2∘=2.8.

  13. Non destructive Testing (NDT) of concrete containing hematite

    International Nuclear Information System (INIS)

    Mohamad Pauzi Ismail; Noor Azreen Masenwat; Suhairy Sani; Nasharuddin Isa; Mohamad Haniza Mahmud

    2014-01-01

    This paper described the results of Non-destructive ultrasonic and rebound hammer measurements on concrete containing hematite. Local hematite stones were used as aggregates to produce high density concrete for application in X-and gamma shielding. Concrete cube samples (150 mm x 150 mm x 150 mm) containing hematite as coarse aggregates were prepared by changing mix ratio, water to cement ratio (w/c) and types of fine aggregate. All samples were cured in water for 7 days and then tested after 28 days. Density, rebound number(N) and ultrasonic pulse velocity (UPV) of the samples were taken before compressed to failure. The measurement results are explained and discussed. (author)

  14. Memory effect of ball-milled and annealed nanosized hematite

    International Nuclear Information System (INIS)

    Bercoff, P.G.; Bertorello, H.R.; Oliva, M.I.

    2007-01-01

    Fine particles of hematite (mean size 55 nm) were produced by ball milling a mixture of hematite and pure Fe and annealing at 1000 o C. X-ray diffraction (XRD) and Moessbauer spectroscopy show that only α-Fe 2 O 3 is present in the final product, with lattice and Moessbauer parameters that correspond to bulk hematite. ZFC and FC magnetization measurements were performed from 5 to 300 K, at different applied fields. Two magnetic regimes were observed: one at low temperatures (≤100 K) that we ascribe to the magnetic moments in the outer shell of the particles that couple to the magnetic moments in the core, and another at higher temperature that corresponds to the Morin transition, finding that the Morin temperature is T M =246 K. The memory effect is clearly observed in magnetic measurements that start from different remanence states and explained as dependent on the ordering of the magnetic moments within the particles

  15. The Escalada Formation: Characterization of a potential chert supply source in the Cantabrian Mountains (NW Spain during prehistory.

    Directory of Open Access Journals (Sweden)

    M. Natividad Fuertes-Prieto

    2016-09-01

    When aiming to demonstrate the use of these materials at archaeological sites the sole macroscopic analysis of the pieces does not suffice; further analyses, such as those involving thin sections, are necessary. The absence of chert from Escalada Formation in some Mesolithic sites in the area was confirmed via these additional analyses.

  16. The chert workshop of Tozal de la Mesa (Alins del Monte, Huesca, Spain and its exploitation in historical times

    Directory of Open Access Journals (Sweden)

    Marta Sánchez de la Torre

    2016-09-01

    The first approach to contextualize the recovered materials of Tozal de la Mesa workshop area has allowed determining an exploitation of the Garumnian cherts that has lasted until the late nineteenth century according to some recovered products (e.g., pottery and to oral sources.

  17. Interfacial Precipitation of Phosphate on Hematite and Goethite

    Directory of Open Access Journals (Sweden)

    Lijun Wang

    2018-05-01

    Full Text Available Adsorption and subsequent precipitation of dissolved phosphates on iron oxides, such as hematite and goethite, is of considerable importance in predicting the bioavailability of phosphates. We used in situ atomic force microscopy (AFM to image the kinetic processes of phosphate-bearing solutions interacting with hematite or goethite surfaces. The nucleation of nanoparticles (1.0–4.0 nm in height of iron phosphate (Fe(III-P phases, possibly an amorphous phase at the initial stages, was observed during the dissolution of both hematite and goethite at the earliest crystallization stages. This was followed by a subsequent aggregation stage where larger particles and layered precipitates are formed under different pH values, ionic strengths, and organic additives. Kinetic analysis of the surface nucleation of Fe-P phases in 50 mM NH4H2PO4 at pH 4.5 showed the nucleation rate was greater on goethite than hematite. Enhanced goethite and hematite dissolution in the presence of 10 mM AlCl3 resulted in a rapid increase in Fe-P nucleation rates. A low concentration of citrate promoted the nucleation, whereas nucleation was inhibited at higher concentrations of citrate. By modeling using PHREEQC, calculated saturation indices (SI showed that the three Fe(III-P phases of cacoxenite, tinticite, and strengite may be supersaturated in the reacted solutions. Cacoxenite is predicted to be more thermodynamically favorable in all the phosphate solutions if equilibrium is reached with respect to hematite or goethite, although possibly only amorphous precipitates were observed at the earliest stages. These direct observations at the nanoscale may improve our understanding of phosphate immobilization in iron oxide-rich acid soils.

  18. Geochemical Characterization Of Cherts From The 3.46Ga Apex Basalt To Assess The Origins Of Possible Biosignatures

    Science.gov (United States)

    Bower, D. M.; Steele, A.; Ackerson, M. R.; Bullock, E. S.; Green, O. R.; Fries, M.; Conrad, P. G.

    2017-12-01

    Many terrestrial cherts contain compelling microtextures and mineral phases that are indicative of ancient life in hydrothermal systems on early Earth. In volcanically-derived hydrothermal deposits, cherts have undergone multiple alteration events often resulting in separate generations of quartz veins that are much younger than the host rocks. In some cases, multiple episodes of hydrothermal alteration obscure otherwise syngenetic biosignatures and likewise create false signatures in the form of secondary carbon emplacement or diagenetic phase changes. To better identify possible biosignatures in hydrothermal deposits and understand their origins, we used confocal micro Raman spectroscopy, electron probe microanalysis, and cathodoluminescence (CL) imaging to characterize the quartz fabrics, mineral phases, trace elements, and macromolecular carbon (MMC) in quartz veins from the 3.46 Ga Apex Basalt chert samples. MMC, anatase (TiO2), pyrite (Fe2S), jarosite-alunite (KFe3(SO4)2(OH)6 - Kal3(SO4)2(OH)6), chamosite-phyllosilicates, and Fe-oxides all occur in close association in multiple generations of quartz veins throughout the sample suite. Mineral phases xenotime (YPO4), scorodite (FeAsO4 . H2O), apatite (CaPO4), pentlandite ((Fe,Ni)9S8), barite (BaSO4), sphalerite ((Zn,Fe)S), dolomite ((CaMg(CO3)2) and halides occur in specific generations of quartz. Trace elements (Cr, Mn, Mo, Cu, Sc, Va, Sb, and Co) are heterogeneously distributed within individual samples and likely occur due to fluid scavenging of the host basalts. CL imaging of quartz demonstrates that the majority of silicate material in the Apex cherts underwent recrystallization. This could result in the alteration of MMC and associated mineral assemblages. The biogencity and true origins of morphological features and chemical signatures in the Apex cherts are hotly debated, yet discovering the causes and nature of these puzzling attributes will be key for determining the usefulness of interrogating

  19. Photosystem I-​based Biophotovoltaics on Nanostructured Hematite

    NARCIS (Netherlands)

    Ocakoglu, K.; Krupnik, T.; van den Bosch, B.; Harputlu, E.; Gullo, M.P.; Olmos, J.D.J.; Yildirimcan, S.; Gupta, R.K.; Yakuphanoglu, F.; Barbieri, A.; Reek, J.N.H.; Kargul, J.

    2014-01-01

    The electronic coupling between a robust red algal photosystem I (PSI) associated with its light harvesting antenna (LHCI) and nanocrystalline n-​type semiconductors, TiO2 and hematite (α-​Fe2O3) is utilized for fabrication of the biohybrid dye-​sensitized solar cells (DSSC)​. PSI-​LHCI is

  20. The rheological behavior of fracture-filling cherts: example of Barite Valley dikes, Barberton Greenstone Belt, South Africa

    Science.gov (United States)

    Ledevin, M.; Arndt, N.; Simionovici, A.

    2014-05-01

    A 100 m-thick complex of near-vertical carbonaceous chert dikes marks the transition from the Mendon to Mapepe Formations (3260 Ma) in the Barberton Greenstone Belt, South Africa. Fracturing was intense in this area, as shown by the profusion and width of the dikes (ca. 1 m on average) and by the abundance of completely shattered rocks. The dike-and-sill organization of the fracture network and the upward narrowing of some of the large veins indicate that at least part of the fluid originated at depth and migrated upward in this hydrothermal plumbing system. Abundant angular fragments of silicified country rock are suspended and uniformly distributed within the larger dikes. Jigsaw-fit structures and confined bursting textures indicate that hydraulic fracturing was at the origin of the veins. The confinement of the dike system beneath an impact spherule bed suggests that the hydrothermal circulations were triggered by the impact and located at the external margin of a large crater. From the geometry of the dikes and the petrography of the cherts, we infer that the fluid that invaded the fractures was thixotropic. On one hand, the injection of black chert into extremely fine fractures is evidence for low viscosity at the time of injection; on the other hand, the lack of closure of larger veins and the suspension of large fragments in a chert matrix provide evidence of high viscosity soon thereafter. The inference is that the viscosity of the injected fluid increased from low to high as the fluid velocity decreased. Such rheological behavior is characteristic of media composed of solid and colloidal particles suspended in a liquid. The presence of abundant clay-sized, rounded particles of silica, carbonaceous matter and clay minerals, the high proportion of siliceous matrix and the capacity of colloidal silica to form cohesive 3-D networks through gelation, account for the viscosity increase and thixotropic behavior of the fluid that filled the veins. Stirring and

  1. The Influence of Several Doped Ions on Gas Sensitivity of Hematite

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    The dehydrating activation energies of the hematite with several doped ions used for the alcohol sensor were determinated by thermogravimetric differential thermal analyzer (TG-DTA) and the grain size of the samples were observed with TEM. The hematites with different doping amounts of Sn4 + were investigated by Mossbauer spectrometer. It shows that the different doped ion is of influence for grain growth of the hematite. The decrease of grain size stemmed from the doped ion causes gas sensitivity for alcohol to increase and the dehydrating activation energy to decrease correspondingly. When the different amounts of Sn4 + is doped in hematite, the microstructure of the hematite can be influenced.

  2. [Anorexia nervosa in light of Karl Jaspers and Erich Fromm's ideas and social constructivism--hypotheses and thoughts].

    Science.gov (United States)

    Talarczyk, Małgorzata

    2012-01-01

    The point of the article is to analyse and reflect on certain symptoms of anorexia nervosa in light of Karl Jaspers and Erich Fromm's ideas and social constructivism. Contemplating the disorder in view of the philosophical ideas mentioned earlier, the author analyses such aspects of patients as: functioning on the verge of life and death, the paradoxical struggle to escape from freedom in search of independence, as well as various understandings and descriptions of anorexia in consideration of social constructivism. The author shares thoughts and poses hypotheses, trying to view anorexia in light of selected philosophical and psychological ideas, which in their general assumptions were not concerned with defining nor analysing anorexia nervosa. In view of Karl Jaspers' ideas, the author focuses on the so called 'limit-situations', in the ideas of Erich Fromm she takes notice in "Escape from Freedom" to new relations. Finally in the light of social constructivism the author focuses on the cultural context.

  3. [The Concept of Typology in Psychiatry in the Context of Historical Contributions of Max Weber and Karl Jaspers].

    Science.gov (United States)

    Jäger, M; Becker, T; Wigand, M E

    2016-08-01

    Against the background of Max Weber's and Karl Jaspers' outstanding historical contributions to the conceptual development of different typologies, the importance of a psychiatric typology is examined. The term "ideal type" was introduced into social science by Weber as an analytical construct to describe and classify cultural phenomena. This concept was adopted for the psychiatric context by Jaspers who proposed to establish a typological system in the field of psychotic disturbances without an organic correlate. He emphasized the importance of the course of psychopathological symptoms for such a typological system. The concept of typology can be regarded as a promising heuristic approach in psychiatry, providing a classification system for complex psychopathological symptoms. Even though several historic typologies exist in psychopathology, their usefulness in the fields of therapy and prognosis needs to be critically assessed. Also, new typologies will have to be developed, taking into account neurobiological knowledge now available. © Georg Thieme Verlag KG Stuttgart · New York.

  4. Effect of magnetic starch on the clarification of hematite tailings wastewater

    Science.gov (United States)

    Yue, Tao; Wu, Xiqing

    2018-02-01

    The magnetic starch solution, synthesized by mixing the caustic starch, the Fe2+ solution (in some cases containing the Zn2+, Cu2+, Mn2+ or Mg2+ ions) and H2O2 solution, was used as the flocculant to investigate its clarification effect on hematite tailings wastewater. Based on the clarification tests and adsorption analysis it was demonstrated that the magnetic starch produced better clarification effect than the caustic starch, and the adsorption of magnetic starch onto hematite tailings particles was also stronger than the caustic starch. AFM found that the magnetic interaction between magnetic seeds and hematite is characteristic of long range force and greatly strengthens the adsorption of magnetic seeds onto fine hematite for agglomeration. FTIR indicates the starch adsorbed onto the surfaces of hematite and magnetic seeds, thus acting as the bridging between hematite particles and magnetic seeds, resulting in an intensified coverage of the starch onto hematite and positive action in the clarification.

  5. Green urea synthesis catalyzed by hematite nanowires in magnetic field

    International Nuclear Information System (INIS)

    Yahya, Noorhana; Qureshi, Saima; Rehman, Zia ur; Alqasem, Bilal; Fai Kait, Chong

    2017-01-01

    The catalytic activity of hematite (α-Fe 2 O 3 ) nanowires under the influence of magnetic field on urea synthesis is considered green. The adsorption and subsequent dissociative reaction of hydrogen, nitrogen and carbon dioxide gases on the α-Fe 2 O 3 (111) nanowires were investigated using the density functional theory (DFT) method. The average adsorption energy is −4.12 kcal/mole at different sites. The adsorption of gases resulted in a difference in density and net spin of electrons from 68 to 120 and 0–21 respectively. In addition, it induces magnetic moment value of 36.33 µB, which confirms the enhanced magnetic behaviour of hematite. α-Fe 2 O 3 nanowires (NWs) synthesized by heating iron wire in a box furnace at (750−800) °C and as synthesized α-Fe 2 O 3 nanoparticles (NPs) were received to use as a catalyst in the magnetic reaction of urea synthesis. X-ray Diffractometer (XRD) confirms the peaks of rhombohedral structure of α-Fe 2 O 3 and Raman spectrum analyses confirms the α-Fe 2 O 3 peaks at 410 cm −1 , 500 cm −1 and 616 cm −1 . The needle-like shape of hematite nanowires with length ranging from 16–25) μm and diameter from 74 to 145 nm confirmed by Field emission scanning electron microscopy (FESEM). The magnetic properties of the nanowires exhibited different levels of saturation magnetization, for α-Fe 2 O 3 perpendicularly aligned direction (13.18 emu/g) and random direction (10.73 emu/g). Urea synthesis was done under magnetic field ranges from 0.0 to 2.5 T. The activation energy of α-Fe 2 O 3 NWs for urea production is lower than NPs in the range of 0–1 T, whereas it is reversed for higher magnetic induction values. Fourier transform infrared spectroscopy (FTIR) confirmed the formation of urea at the peaks of 1690–1600 cm −1 . This green urea employing magnetically induced method could be a contender to the Haber-Bosch process currently used by the current industry which utilizes high temperature and high pressure

  6. Field and numerical descriptions of fracture geometries and terminations in chalk containing chert layers and inclusions; implications for groundwater flow in Danish chalk aquifers

    Science.gov (United States)

    Seyum, S.

    2017-12-01

    This study is a description of the fracture distribution in laterally discontinuous chalk and chert layers, with an investigation on how fracture lengths and apertures vary as a function of applied stresses, material properties, and interface properties. Natural fractures intersect laterally extensive, discontinuous, chalk-chert material interfaces in 62 million-year old to 72 million-year old Chalk Group formations exposed at Stevns Klint, Denmark. Approximately one-third of Denmark's fresh water use is from chalk and limestone regional aquifers of the Chalk Group formations, where rock permeability is dominantly a function of open fracture connectivities. Fractured, centimeter- to decimeter-thick chert layers and inclusions (101 GPa elastic stiffness) are interlayered with fractured, meter-thick chalk layers (100 GPa elastic stiffness). Fractures are observed to terminate against and cross chalk-chert interfaces, affecting the vertical flow of water and pollutants between aquifers. The discontinuous and variably thin nature of chert layers at Stevns Klint effectively merges adjacent fracture-confining layers of chalk along discrete position intervals, resulting in lateral variability of fracture spacing. Finite element numerical models are designed to describe fracture interactions with stiff, chert inclusions of various shapes, thicknesses, widths, orientations, and interface friction and fracture toughness values. The models are two-dimensional with isotropic, continuous material in plane strain and uniformly applied remote principal stresses. These characteristics are chosen based on interpretations of the petrophysics of chalk and chert, the burial history of the rock, and the scale of investigation near fracture tips relative to grain sizes. The result are value ranges for relative stiffness contrasts, applied stresses, and material interface conditions that would cause fractures to cross, terminate at, or form along chalk-chert interfaces, with emphasis on

  7. A community responds to collective trauma: an ecological analysis of the James Byrd murder in Jasper, Texas.

    Science.gov (United States)

    Wicke, Thomas; Silver, Roxane Cohen

    2009-12-01

    The brutal murder of James Byrd Jr. in June 1998 unleashed a storm of media, interest groups, high profile individuals and criticism on the Southeast Texas community of Jasper. The crime and subsequent response-from within the community as well as across the world-engulfed the entire town in a collective trauma. Using natural disaster literature/theory and employing an ecological approach, Jasper, Texas was investigated via an interrupted time series analysis to identify how the community changed as compared to a control community (Center, Texas) on crime, economic, health, educational, and social capital measures collected at multiple pre- and post-crime time points between 1995 and 2003. Differences-in-differences (DD) analysis revealed significant post-event changes in Jasper, as well as a surprising degree of resilience and lack of negative consequences. Interviews with residents conducted between March 2005 and 2007 identified how the community responded to the crisis and augmented quantitative findings with qualitative, field-informed interpretation. Interviews suggest the intervention of external organizations exacerbated the severity of the events. However, using strengths of specific local social institutions-including faith based, law enforcement, media, business sector and civic government organizations-the community effectively responded to the initial threat and to the potential negative ramifications of external entities.

  8. The nature of hematite depression with corn starch in the reverse flotation of iron ore.

    Science.gov (United States)

    Shrimali, Kaustubh; Atluri, Venkata; Wang, Yan; Bacchuwar, Sanket; Wang, Xuming; Miller, Jan D

    2018-08-15

    The function of corn starch and the significance of the order of addition of corn starch and mono ether amine in the reverse flotation of iron ore has been investigated. Understanding hematite depression with starch and the corresponding hydrophilic state involves consideration of adsorption with amine as well as flocculation of fine hematite. Captive bubble contact angle and micro-flotation experiments indicated that amine has an affinity towards both hematite and quartz, and that the role of starch is to hinder the adsorption of amine at the hematite surface so that flotation is inhibited. Micro-flotation results confirmed that quartz does not have affinity towards starch at pH 10.5. In addition to competitive adsorption, flocculation of fine hematite occurs and images from high resolution X-ray computed tomography (HRXCT) and cryo-SEM reveal further detail regarding floc structure. These results provide substantial evidence that the fine hematite particles are flocculated in the presence of corn starch, and flocculation is dependent on the particle size of hematite, with greater flocculation for finer particles. Thus, starch is playing a dual role in the reverse flotation of iron ore, acting as a depressant by hindering amine adsorption at the hematite surface in order to maintain the hydrophilic surface state of hematite, and acting as a flocculant to aggregate fine hematite particles, which if not flocculated, could diminish the flotation separation efficiency by being transported to the froth phase during reverse flotation. Copyright © 2018 Elsevier Inc. All rights reserved.

  9. Paleomagnetic and oxygen isotopic evidence for long term diagenesis in radiolarian chert, Pindos Mountains, Greece

    Science.gov (United States)

    Baltuck, Miriam

    1987-02-01

    Paleomagnetics was used in an attempt to improve chronostratigraphy in the Middle and Upper Jurassic radiolarian chert and siliceous mudstone of the Pindos Zone, Greece. Remanent magnetism studies showed strong magnetic intensity but scattered orientation. Orientation of some pressure solution features in the radiolarities indicates their formation under horizontal pressure, a condition which in Pindos geologic history would only have occurred during early Cretaceous or Cenozoic tectonics, indicating very late diagenesis in these parts of the section. From time of deposition to later time at which diagenesis can be documented, the Earth's magnetic field would have reversed many times. Remagnetization during solution-precipitation steps of silica diagenesis could complicate the rock magnetics. Oxygen isotopic and major element analyses of radiolarite lithologies show a systematic variation of rate of silica diagenesis in different host lithologies, thus solution-precipitation would occur at widely differing times throughout the section lithologies. If the dissolution of the silica cement were physically to free magnetic material from an earlier orientation, the result could be a partial shift toward alignment with the ambient magnetic field. Alternatively, complete reorientation of particles could have occurred at varying times in different parts of the section as a function of host lithology. During the northward movement and clockwise rotation of the Apulian subplate (including Pindos) these different lithologies could completely reorient during different stages of silica diagenesis, locking the orientation of iron magnetic moments into alignment with the ambient magnetic field at time of precipitation to result in a strong intensity but scattered orientation of Pindos rock magnetics.

  10. Fine hematite particles of Martian interest: absorption spectra and optical constants

    International Nuclear Information System (INIS)

    Marra, A C; Blanco, A; Fonti, S; Jurewicz, A; Orofino, V

    2005-01-01

    Hematite is an iron oxide very important for the study of climatic evolution of Mars. It can occur in two forms: red and grey, mainly depending on the granulometry of the samples. Spectra of bright regions of Mars suggest the presence of red hematite particles. Moreover the Thermal Emission Spectrometer (TES), on board the Mars Global Surveyor mission, has discovered a deposit of crystalline grey hematite in Sinus Meridiani. TES spectra of that Martian region exhibit features at about 18, 23 and 33 μm that are consistent with hematite. Coarse grey hematite is considered strong evidence for longstanding water, while it is unknown whether the formation of fine-grained red hematite requires abundant water. Studies are needed in order to further characterize the spectral properties of the two kinds of hematite. For this reason we have analyzed a sample of submicron hematite particles in the 6.25-50 μm range in order to study the influence of particles size and shape on the infrared spectra. The optical constants of a particulate sample have been derived and compared with published data concerning bulk samples of hematite. Our results seem to indicate that particle shape is an important factor to take into account for optical constants derivation

  11. Chemical and Mineralogical Characterization of a Hematite-bearing Ridge on Mauna Kea, Hawaii: A Potential Mineralogical Process Analog for the Mount Sharp Hematite Ridge

    Science.gov (United States)

    Graff, T. G.; Morris, R. V.; Ming, D. W.; Hamilton, J. C.; Adams, M.; Fraeman, A. A.; Arvidson, R. E.; Catalano, J. G.; Mertzman, S. A.

    2014-01-01

    The Mars Science Laboratory (MSL) rover Curiosity landed in Gale Crater in August 2012 and is currently roving towards the layered central mound known as Mount Sharp [1]. Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) hyperspectral data indicate Mount Sharp contains an 5 km stratigraphic sequence including Fe-Mg smectites, hematite, and hydrated sulfates in the lower layers separated by an unconformity from the overlying anhydrous strata [1,2,3]. Hematite was initially detected in CRISM data to occur in the lower sulfate layers on the north side of the mound [2]. [3] further mapped a distinct hematite detection occurring as part of a 200 m wide ridge that extends 6.5 km NE-SW, approximately parallel with the base of Mount Sharp. It is likely a target for in-situ analyses by Curiosity. We document here the occurrence of a stratum of hematite-bearing breccia that is exposed on the Puu Poliahu cinder cone near the summit of Mauna Kea volcano (Hawaii) (Fig.1). The stratum is more resistant to weathering than surrounding material, giving it the appearance of a ridge. The Mauna Kea hematite ridge is thus arguably a potential terrestrial mineralogical and process analog for the Gale Crater hematite ridge. We are acquiring a variety of chemical and mineralogical data on the Mauna Kea samples, with a focus on the chemical and mineralogical information already available or planned for the Gale hematite ridge.

  12. Green urea synthesis catalyzed by hematite nanowires in magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Yahya, Noorhana, E-mail: noorhana_yahya@petronas.com.my; Qureshi, Saima; Rehman, Zia ur; Alqasem, Bilal; Fai Kait, Chong

    2017-04-15

    The catalytic activity of hematite (α-Fe{sub 2}O{sub 3}) nanowires under the influence of magnetic field on urea synthesis is considered green. The adsorption and subsequent dissociative reaction of hydrogen, nitrogen and carbon dioxide gases on the α-Fe{sub 2}O{sub 3} (111) nanowires were investigated using the density functional theory (DFT) method. The average adsorption energy is −4.12 kcal/mole at different sites. The adsorption of gases resulted in a difference in density and net spin of electrons from 68 to 120 and 0–21 respectively. In addition, it induces magnetic moment value of 36.33 µB, which confirms the enhanced magnetic behaviour of hematite. α-Fe{sub 2}O{sub 3} nanowires (NWs) synthesized by heating iron wire in a box furnace at (750−800) °C and as synthesized α-Fe{sub 2}O{sub 3} nanoparticles (NPs) were received to use as a catalyst in the magnetic reaction of urea synthesis. X-ray Diffractometer (XRD) confirms the peaks of rhombohedral structure of α-Fe{sub 2}O{sub 3} and Raman spectrum analyses confirms the α-Fe{sub 2}O{sub 3} peaks at 410 cm{sup −1}, 500 cm{sup −1} and 616 cm{sup −1}. The needle-like shape of hematite nanowires with length ranging from 16–25) μm and diameter from 74 to 145 nm confirmed by Field emission scanning electron microscopy (FESEM). The magnetic properties of the nanowires exhibited different levels of saturation magnetization, for α-Fe{sub 2}O{sub 3} perpendicularly aligned direction (13.18 emu/g) and random direction (10.73 emu/g). Urea synthesis was done under magnetic field ranges from 0.0 to 2.5 T. The activation energy of α-Fe{sub 2}O{sub 3} NWs for urea production is lower than NPs in the range of 0–1 T, whereas it is reversed for higher magnetic induction values. Fourier transform infrared spectroscopy (FTIR) confirmed the formation of urea at the peaks of 1690–1600 cm{sup −1}. This green urea employing magnetically induced method could be a contender to the Haber-Bosch process

  13. Reductive Dissolution of Goethite and Hematite by Reduced Flavins

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Zhi; Zachara, John M.; Wang, Zheming; Shi, Liang; Fredrickson, Jim K.

    2013-10-02

    The abiotic reductive dissolution of goethite and hematite by the reduced forms of flavin mononucleotide (FMNH2) and riboflavin (RBFH2), electron transfer mediators (ETM) secreted by the dissimilatory iron-reducing bacterium Shewanella, was investigated under stringent anaerobic conditions. In contrast to the rapid redox reaction rate observed for ferrihydrite and lepidocrocite (Shi et al., 2012), the reductive dissolution of crystalline goethite and hematite was slower, with the extent of reaction limited by the thermodynamic driving force at circumneutral pH. Both the initial reaction rate and reaction extent increased with decreasing pH. On a unit surface area basis, goethite was less reactive than hematite between pH 4.0 and 7.0. AH2DS, the reduced form of the well-studied synthetic ETM anthraquinone-2,6-disulfonate (AQDS), yielded higher rates than FMNH2 under most reaction conditions, despite the fact that FMNH2 was a more effective reductant than AH2DS for ferryhydrite and lepidocrocite. Two additional model compounds, methyl viologen and benzyl viologen, were investigated under similar reaction conditions to explore the relationship between reaction rate and thermodynamic properties. Relevant kinetic data from the literature were also included in the analysis to span a broad range of half-cell potentials. Other conditions being equal, the surface area normalized initial reaction rate (ra) increased as the redox potential of the reductant became more negative. A non-linear, parabolic relationship was observed between log ra and the redox potential for eight reducants at pH 7.0, as predicted by Marcus theory for electron transfer. When pH and reductant concentration were fixed, log ra was positively correlated to the redox potential of four Fe(III) oxides over a wide pH range, following a non-linear parabolic relationship as well.

  14. An inelastic neutron scattering study of hematite nanoparticles

    DEFF Research Database (Denmark)

    Hansen, Mikkel Fougt; Klausen, Stine Nyborg; Lefmann, K

    2003-01-01

    We have studied the magnetic dynamics in nanocrystalline hematite by inelastic neutron scattering at the high-resolution time-of-flight spectrometer IRIS at ISIS. Compared to previous inelastic neutron scattering experiments an improvement of the resolution function is achieved and more detailed...... moment at the antiferromagnetic Bragg reflection. We have studied different weightings of the particle size distribution. The data and their temperature dependence can with good agreement be interpreted on the basis of the Neel-Brown theory for superparamagnetic relaxation and a model for the collective...

  15. Magnetic anisotropy and quantized spin waves in hematite nanoparticles

    DEFF Research Database (Denmark)

    Klausen, Stine Nyborg; Lefmann, Kim; Lindgård, Per-Anker

    2004-01-01

    We report on the observation of high-frequency collective magnetic excitations, (h) over bar omegaapproximate to1.1 meV, in hematite (alpha-Fe2O3) nanoparticles. The neutron scattering experiments include measurements at temperatures in the range 6-300 K and applied fields up to 7.5 T as well...... as polarization analysis. We give an explanation for the field- and temperature dependence of the excitations, which are found to have strongly elliptical out-of-plane precession. The frequency of the excitations gives information on the magnetic anisotropy constants in the system. We have in this way determined...

  16. Electrochemical preparation of hematite nanostructured films for solar hydrogen production

    Directory of Open Access Journals (Sweden)

    Ebadzadeh T.

    2012-10-01

    Full Text Available Photoelectrochemical water splitting is a clean and promising technique for using a renewable source of energy, i.e., solar energy, to produce hydrogen. In this work electrochemical formation of iron oxyhydroxide and its conversion to hematite (α- Fe2O3 through thermal treatment have been studied. Oxyhydroxide iron compounds have been prepared onto SnO2/F covered glass substrate by potential cycling with two different potential sweep rate values; then calcined at 520 °C in air to obtain α-Fe2O3 nanostrutured films for their implementation as photoanode in a photoelectrochemical cell. X-ray diffraction analysis allowed finding that iron oxides films have nanocrystalline character. Scanning electron microscopy revealed that films have nanostructured morphology. The obtained results are discussed considering the influence of potential sweep rate employed during the preparation of iron oxyhydroxide film on optical, structural and morphological properties of hematite nanostructured films. Results show that films have acceptable characteristics as photoanode in a photoelectrochemical cell for hydrogen generation from water.

  17. Interaction of light with hematite hierarchical structures: Experiments and simulations

    Science.gov (United States)

    Distaso, Monica; Zhuromskyy, Oleksander; Seemann, Benjamin; Pflug, Lukas; Mačković, Mirza; Encina, Ezequiel; Taylor, Robin Klupp; Müller, Rolf; Leugering, Günter; Spiecker, Erdmann; Peschel, Ulf; Peukert, Wolfgang

    2017-03-01

    Mesocrystalline particles have been recognized as a class of multifunctional materials with potential applications in different fields. However, the internal organization of nanocomposite mesocrystals and its influence on the final properties have not yet been investigated. In this paper, a novel strategy based on electrodynamic simulations is developed to shed light on how the internal structure of mesocrystals influences their optical properties. In a first instance, a unified design protocol is reported for the fabrication of hematite/PVP particles with different morphologies such as pseudo-cubes, rods-like and apple-like structures and controlled particle size distributions. The optical properties of hematite/PVP mesocrystals are effectively simulated by taking their aggregate and nanocomposite structure into consideration. The superposition T-Matrix approach accounts for the aggregate nature of mesocrystalline particles and validate the effective medium approximation used in the framework of the Mie theory and electromagnetic simulation such as Finite Element Method. The approach described in our paper provides the framework to understand and predict the optical properties of mesocrystals and more general, of hierarchical nanostructured particles.

  18. Adsorption of ions on hematite (α-Fe2O3) : a colloid-chemical study

    NARCIS (Netherlands)

    Breeuwsma, A.

    1973-01-01

    This study is primarily intended to provide a better understanding of the adsorption of ions on hematite (α-Fe 2 O 3 ). In addition, due attention is given to the relation between the ionic adsorption and the colloidal stability of hematite sols.

    Chapter 1. is concerned

  19. Immobilization of molecular cobalt electrocatalyst by hydrophobic interaction with hematite photoanode for highly stable oxygen evolution

    KAUST Repository

    Joya, Khurram

    2015-07-15

    A unique modification of a hematite photoanode with perfluorinated Co-phthalocyanine (CoFPc) by strong binding associated with hydrophobic interaction is demonstrated. The resultant molecular electrocatalyst – hematite photoanode hybrid material showed significant onset shift and high stability for photoelectrochemical oxidation evolution reaction (OER).

  20. Residual Energy Harvesting from Light Transients Using Hematite as an Intrinsic Photocapacitor in a Symmetrical Cell

    NARCIS (Netherlands)

    Blom, Burgert; van Leeuwen, Nicole; Xie, Mengying; Adamaki, Vana; Bowen, Chris R.; de Araujo, Moises A.; Mascaro, Lucia H.; Cameron, Petra J.; Marken, Frank

    2017-01-01

    Hematite as a sustainable photoabsorber material offers a band gap close to 2 eV and photoanode characteristics, but usually requires additional catalysts to enhance surface redox chemistry during steady state light energy harvesting for water splitting. Here, for a highly doped hematite film,

  1. Immobilization of molecular cobalt electrocatalyst by hydrophobic interaction with hematite photoanode for highly stable oxygen evolution

    KAUST Repository

    Joya, Khurram; Morlanes, Natalia; Maloney, Edward; Rodionov, Valentin; Takanabe, Kazuhiro

    2015-01-01

    A unique modification of a hematite photoanode with perfluorinated Co-phthalocyanine (CoFPc) by strong binding associated with hydrophobic interaction is demonstrated. The resultant molecular electrocatalyst – hematite photoanode hybrid material showed significant onset shift and high stability for photoelectrochemical oxidation evolution reaction (OER).

  2. Biogeochemical and micropaleontological study of black chert, Sete Lagoas Formation, Bambui Group (Late Proterozoic), Sao Gabriel (GO), Brazil

    International Nuclear Information System (INIS)

    Subacius, S.M.R.

    1985-01-01

    The biogeochemical study of amorphous and structured organic matter (OM) in two samples of thinly laminated black cherts (SG-1 and SG-2) from Sete Lagoas Formation, State of Goias, Brazil, is presented. The spectra analysis of infra-red, electron paramagnetic resonance and isotope ratio of C-12 and C-13 shown that: the amorphous OM consists of a soluble fraction (SF) and a insoluble fraction (Kerogen), which only the latter is syngenetic; the allochthonous SF comes from several sources, mainly from Phanerozoic sediments and soil contamination; the SG-1 and SG-2 Kerogens have δ 13 C values (-27.2 per mille and - 29.2 per mille respectively), which suggest OM photosynthetized and submitted to a mild thermal hystory; although the preserved microbiota is dominated by allochthonous elements (colonial fragments) and planktonic forms, both Kerogens were derived for the most part from photo-autotrophic benthonic communities, probably responsible for the lamination in the original carbonate rock, both SG-1 and SG-2 Kerogens exhibits O/C and H/C ratios comparable to Proterozoic humic Kerogens (type IV); the preserved microflora represents a microbial community of the chert-algae facies typical of the Middle and upper Proterozoic; and the occurence of rare acritarchs (Kildinella spp.) in the microflora is biostratigraphically significant in that it suggests a Late Riphean or Vendian age (950-570 m.y.) for the Sete Lagoas Formation. (Author) [pt

  3. In situ Ni-doping during cathodic electrodeposition of hematite for excellent photoelectrochemical performance of nanostructured nickel oxide-hematite p-n junction photoanode

    Science.gov (United States)

    Phuan, Yi Wen; Ibrahim, Elyas; Chong, Meng Nan; Zhu, Tao; Lee, Byeong-Kyu; Ocon, Joey D.; Chan, Eng Seng

    2017-01-01

    Nanostructured nickel oxide-hematite (NiO/α-Fe2O3) p-n junction photoanodes synthesized from in situ doping of nickel (Ni) during cathodic electrodeposition of hematite were successfully demonstrated. A postulation model was proposed to explain the fundamental mechanism of Ni2+ ions involved, and the eventual formation of NiO on the subsurface region of hematite that enhanced the potential photoelectrochemical water oxidation process. Through this study, it was found that the measured photocurrent densities of the Ni-doped hematite photoanodes were highly dependent on the concentrations of Ni dopant used. The optimum Ni dopant at 25 M% demonstrated an excellent photoelectrochemical performance of 7-folds enhancement as compared to bare hematite photoanode. This was attributed to the increased electron donor density through the p-n junction and thus lowering the energetic barrier for water oxidation activity at the optimum Ni dopant concentration. Concurrently, the in situ Ni-doping of hematite has also lowered the photogenerated charge carrier transfer resistance as measured using the electrochemical impedance spectroscopy. It is expected that the fundamental understanding gained through this study is helpful for the rational design and construction of highly efficient photoanodes for application in photoelectrochemical process.

  4. Shielding design study of the demonstration fast breeder reactor. 2. Shielding design on the basis of the JASPER analysis

    International Nuclear Information System (INIS)

    Suzuoki, Zenro; Tabayashi, Masao; Handa, Hiroyuki; Iida, Masaaki; Takemura, Morio

    2000-01-01

    Conceptual shielding design has been performed for the Demonstration Fast Breeder Reactor (DFBR) to achieve further optimization and reduction of the plant construction cost. The design took into account its implications in overall plant configuration such as reduction of shields in the core, adoption of fission gas plenum in the lower portion of fuel assemblies, and adoption of gas expansion modules. Shielding criteria applied for the design are to secure fast neutron fluence on in-vessel structures as well as responses of the nuclear instrumentation system and to restrict secondary sodium activation. The design utilized the cross sections and the one- and two-dimensional discrete ordinates transport codes, whose verification had been performed by the JASPER experiment analysis. Correction factors yielded by the JASPER analysis were applied to the design calculations to obtain design values with improved accuracy. Design margins, which are defined by the ratios of the design criteria to the design values, were more than two for all shielding issues of interest, showing the adequacy of the shielding design of the DFBR. (author)

  5. On psychodynamics of personal value-judgements - Nietzsche's theory of resentment and its reception by Karl Jaspers and Kurt Schneider.

    Science.gov (United States)

    Bormuth, Matthias

    2009-06-01

    A hundred years ago when Karl Jaspers was introducing psychological understanding to psychiatry the founder of the school of Heidelberg spoke of Friedrich Nietzsche as one of the "greatest" psychologists. Especially his theory of resentment with its core thesis unconscious prejudices were influencing our behaviour was able to illuminate the complex structure of human will. Taking into account this horizon of psychiatric history of ideas the presentation wants to persecute the following three questions: 1) Why the postulate which Nietzsche was giving on cultural prejudices of our thoughts, feelings and acts was so provocative so that many of the classical thinkers of psychological understanding were taking it up according to the needs of their disciplines sociology, psychology, psychiatry and philosophy? 2) What were the results of this inspiring theory which could be especially seen in the works of Karl Jaspers and Kurt Schneider? In other words: What were the aspects in which they agreed in their reception of Nietzsche and what were the points in which the two psychiatrists of the school of Heidelberg differed in the way they took the theory of resentment into account for their psychological understanding? 3) What could be the actual significance of the historical fact that Nietzsche and in his footsteps Max Weber were taking deep influence on psychiatric thinking around 1900?

  6. Hematite mining in the ancient Americas: Mina Primavera, A 2,000 year old Peruvian mine

    Science.gov (United States)

    Vaughn, Kevin J.; Grados, Moises Linares; Eerkens, Jelmer W.; Edwards, Matthew J.

    2007-12-01

    Mina Primavera, a hematite (Fe2O3) mine located in southern Peru, was exploited beginning approximately 2,000 years ago by two Andean civilizations, the Nasca and Wari. Despite the importance of hematite in the material culture of the ancient Americas, few hematite mines have been reported in the New World literature and none have been reported for the Central Andes. An estimated 3,710 tonnes of hematite were extracted from the mine for over 1,400 years at an average rate of 2.65 tonnes per year, suggesting regular and extensive mining prior to Spanish conquest. The hematite was likely used as a pigment for painting pottery, and the mine demonstrates that iron ores were extracted extensively at an early date in the Americas.

  7. Spherulitic (c-axis) Growth for Terrestrial (Mauna Kea, Hawaii) and Martian Hematite "blueberries"

    Science.gov (United States)

    Golden, D. C.; Ming, D. W.; Morris, R. V.

    2006-01-01

    Hematite concentrations observed by Thermal Emission Spectrometer (TES) onboard Mars Global Surveyor were considered a possible indicator for aqueous processes on Mars. Observations made by Opportunity show that the hematite at Meridiani Planum is present as spherules ( blueberries) and their fragments. The internal structure of the hematite spherules is not discernable at the resolution limit (approx.30 m/pixel) of Opportunity s Microscopic Imager (MI). A terrestrial analog for martian hematite spherules are spherules from hydrothermally altered and sulfate-rich tephra from the summit region of Mauna Kea volcano, Hawaii. The objective of this study is to determine the crystal growth fabric of the Mauna Kea hematite spherules using transmission electron microscopy (TEM) techniques and to relate that crystalline fabric to the observed TES signature of Meridiani Planum "blueberries." TEM analysis of Mauna Kea spherules exhibited a radial growth pattern consisting of "fibrous" hematite with the c-axis of hematite particles aligned along the elongation direction of the hematite fibers. The individual fibers appear to be made of coalesced nano-particles of hematite arranged with their c-axis oriented radially to form a spherical structure. Lattice fringes suggest long-range order across particles and along fibers. According to interpretations of thermal emission spectra for Meridian Planum hematite, the absence of a band at approx. 390/cm implies a geometry where c-face emission dominates. Because the c-face is perpendicular to the c-axis, this is precisely the geometry for the Mauna Kea spherules because the c-axis is aligned parallel to their radial growth direction. Therefore, we conclude as a working hypothesis that the martian spherules also have radial, c-axis growth pattern on a scale that is too small to be detected by the MER MI. Furthermore, by analogy with the Mauna Kea spherules, the martian blueberries could have formed during hydrothermal alteration of

  8. Green urea synthesis catalyzed by hematite nanowires in magnetic field

    Science.gov (United States)

    Yahya, Noorhana; Qureshi, Saima; Rehman, Zia ur; Alqasem, Bilal; Fai Kait, Chong

    2017-04-01

    The catalytic activity of hematite (α-Fe2O3) nanowires under the influence of magnetic field on urea synthesis is considered green. The adsorption and subsequent dissociative reaction of hydrogen, nitrogen and carbon dioxide gases on the α-Fe2O3 (111) nanowires were investigated using the density functional theory (DFT) method. The average adsorption energy is -4.12 kcal/mole at different sites. The adsorption of gases resulted in a difference in density and net spin of electrons from 68 to 120 and 0-21 respectively. In addition, it induces magnetic moment value of 36.33 μB, which confirms the enhanced magnetic behaviour of hematite. α-Fe2O3 nanowires (NWs) synthesized by heating iron wire in a box furnace at (750-800) °C and as synthesized α-Fe2O3 nanoparticles (NPs) were received to use as a catalyst in the magnetic reaction of urea synthesis. X-ray Diffractometer (XRD) confirms the peaks of rhombohedral structure of α-Fe2O3 and Raman spectrum analyses confirms the α-Fe2O3 peaks at 410 cm-1, 500 cm-1 and 616 cm-1. The needle-like shape of hematite nanowires with length ranging from 16-25) μm and diameter from 74 to 145 nm confirmed by Field emission scanning electron microscopy (FESEM). The magnetic properties of the nanowires exhibited different levels of saturation magnetization, for α-Fe2O3 perpendicularly aligned direction (13.18 emu/g) and random direction (10.73 emu/g). Urea synthesis was done under magnetic field ranges from 0.0 to 2.5 T. The activation energy of α-Fe2O3 NWs for urea production is lower than NPs in the range of 0-1 T, whereas it is reversed for higher magnetic induction values. Fourier transform infrared spectroscopy (FTIR) confirmed the formation of urea at the peaks of 1690-1600 cm-1. This green urea employing magnetically induced method could be a contender to the Haber-Bosch process currently used by the current industry which utilizes high temperature and high pressure.

  9. Examples of Savannah River water dilution between the Savannah River Plant and the Beaufort-Jasper and Port Wentworth water-treatment plants

    International Nuclear Information System (INIS)

    Hayes, D.W.

    1983-01-01

    A substantial dilution of the river water occurs between the Savannah River Plant (SRP) and the two treatment plants. This dilution results from inflow of surface and groundwater and from direct rainfall. The amount of dilution was estimated to be approximately 20% and 54% down to the Port Wentworth and Beaufort-Jasper plants, respectively

  10. Magnetic dynamics of weakly and strongly interacting hematite nanoparticles

    DEFF Research Database (Denmark)

    Hansen, Mikkel Fougt; Bender Koch, Christian; Mørup, Steen

    2000-01-01

    The magnetic dynamics of two differently treated samples of hematite nanoparticles from the same batch with a particle size of about 20 nm have been studied by Mossbauer spectroscopy. The dynamics of the first sample, in which the particles are coated and dispersed in water, is in accordance with...... down by interparticle interactions and a magnetically split spectrum is retained at room temperature. The temperature variation or the magnetic hyperfine field, corresponding to different quantiles in the hyperfine field distribution, can be consistently described by a mean field model...... for "superferromagnetism" in which the magnetic anisotropy is included. The coupling between the particles is due to exchange interactions and the interaction strength can be accounted for by just a few exchange bridges between surface atoms in neighboring crystallites....

  11. Nanostructured hematite thin films for photoelectrochemical water splitting

    Science.gov (United States)

    Maabong, Kelebogile; Machatine, Augusto G. J.; Mwankemwa, Benard S.; Braun, Artur; Bora, Debajeet K.; Toth, Rita; Diale, Mmantsae

    2018-04-01

    Nanostructured hematite thin films prepared by dip coating technique were investigated for their photoelectrochemical activity for generation of hydrogen from water splitting. Structural, morphological and optical analyses of the doped/undoped films were performed by X-ray diffraction, high resolution field emission-scanning electron microscopy, UV-vis spectrophotometry and Raman spectroscopy. The photoelectrochemical measurements of the films showed enhanced photoresponse and cathodic shift of the onset potential upon Ti doping indicating improved transfer of photoholes at the semiconductor-electrolyte interface. Films doped with 1 at% Ti produced 0.72 mA/cm2 at 1.23 V vs RHE which is 2 times higher than current density for the pure film (0.30 mA/cm2, at 1.23 V vs RHE). Gas chromatography analysis of the films also showed enhanced hydrogen evolution at 1 at% Ti with respect to pure film.

  12. Disposal of coal and hematite dusts inhaled successively

    Energy Technology Data Exchange (ETDEWEB)

    Heppleston, A G

    1958-01-01

    Rabbits and rats were exposed in a chamber to coal (20,000 and 10,000 particles/ml) and hematite (20,000 and 37,000 particles/ml) in succession to follow deposition and clearance by color. Exposures were 5 days/wk, 20 hr/day. Generally, there was dust widely but not uniformly distributed in peripheral alveoli, tending to aggregate and clump in more proximal alveoli with time. There was initial nonuniform distribution more uniform with exposure time. Aggregation mostly through phagocyte activities and more evident in rabbits than rats was observed. There was eventual mixing of two dusts inhaled up to 7 months apart. Dust deposited last is cleared first because of less tortuous route.

  13. Microstructural changes in porous hematite nanoparticles upon calcination

    DEFF Research Database (Denmark)

    Johnsen, Rune; Knudsen, Kenneth D.; Molenbroek, Alfons M.

    2011-01-01

    This combined study using small-angle neutron scattering (SANS), X-ray powder diffraction (XRPD), transmission electron microscopy (TEM) and adsorption isotherm techniques demonstrates radical changes in the microstructure of porous hematite (-Fe2O3) nanoparticles upon calcination in air. TEM....... The change in microstructure also causes a reduction in the surface area as calculated by gaseous adsorption. The XRPD and SANS data show that the crystallite and SANS particle sizes are virtually unchanged by calcination at 623 K. Calcination at 973 K induces a significant alteration of the sample. The XRPD...... data reveal that the crystallite size increases significantly, and the SANS and adsorption isotherm studies suggest that the specific surface area decreases by a factor of 5–6. The TEM images show that the particles are sintered into larger agglomerates, but they also show that parts of the porous...

  14. Fixing arsenic contained in a gas phase using solid hematite

    International Nuclear Information System (INIS)

    Balladares, E.; Gonzalez, A.; Rarra, R.; Sanchez, M.

    2004-01-01

    Feasibility to obtain ferric arsenate starting from arsenic containing gas in contact with Fe 3 O 3 has been studied. Thermodynamic stability of the system Fe-As-O was analysed in order to verify conditions to form Fe x As y O z type compounds. Experiments were made using a hematite sample suspended in a thermogravimetric device. As 4 O 6 was generated starting from solid As 2 O 3 which was circulating through the iron oxide. Final samples were analysed chemically and by means of DRX, verifying the formation of FeAsO 4 , FeAsO 4 .2h 2 O and FeAsO 4 .(H 2 O) 2 in small quantities. Tests in porous bed and pellets were carried out, studying the effect of: porosity, temperature and oxygen potential. The largest conversion obtained was 10% at 800 degree centigrade, pO 2 =50% and porosity=0.883. (Author) 9 refs

  15. In situ Ni-doping during cathodic electrodeposition of hematite for excellent photoelectrochemical performance of nanostructured nickel oxide-hematite p-n junction photoanode

    Energy Technology Data Exchange (ETDEWEB)

    Phuan, Yi Wen, E-mail: phuan.yi.wen@monash.edu [School of Engineering, Chemical Engineering Discipline, Monash University Malaysia, Jalan Lagoon Selatan, Bandar Sunway, Selangor DE 47500 (Malaysia); Ibrahim, Elyas, E-mail: meibr2@student.monash.edu [School of Engineering, Chemical Engineering Discipline, Monash University Malaysia, Jalan Lagoon Selatan, Bandar Sunway, Selangor DE 47500 (Malaysia); Chong, Meng Nan, E-mail: Chong.Meng.Nan@monash.edu [School of Engineering, Chemical Engineering Discipline, Monash University Malaysia, Jalan Lagoon Selatan, Bandar Sunway, Selangor DE 47500 (Malaysia); Sustainable Water Alliance, Advanced Engineering Platform, Monash University Malaysia, Jalan Lagoon Selatan, Bandar Sunway, Selangor DE 47500 (Malaysia); Zhu, Tao, E-mail: zhu.tao@monash.edu [School of Engineering, Chemical Engineering Discipline, Monash University Malaysia, Jalan Lagoon Selatan, Bandar Sunway, Selangor DE 47500 (Malaysia); Lee, Byeong-Kyu, E-mail: bklee@ulsan.ac.kr [Department of Civil and Environmental Engineering, University of Ulsan, Nam-gu, Daehakro 93, Ulsan 680-749 (Korea, Republic of); Ocon, Joey D., E-mail: jdocon@up.edu.ph [Laboratory of Electrochemical Engineering (LEE), Department of Chemical Engineering, University of the Philippines Diliman, Quezon City 1101 (Philippines); Chan, Eng Seng, E-mail: chan.eng.seng@monash.edu [School of Engineering, Chemical Engineering Discipline, Monash University Malaysia, Jalan Lagoon Selatan, Bandar Sunway, Selangor DE 47500 (Malaysia)

    2017-01-15

    Highlights: • NiO-hematite p-n junction photoanodes were fabricated via an in situ Ni-doping. • The fundamental mechanism of Ni{sup 2+} ions involved was elucidated. • The optimum Ni dopant was 25 M% for the highest photocurrent density. • It exhibited an excellent photoelectrochemical performance of 7-folds enhancement. - Abstract: Nanostructured nickel oxide-hematite (NiO/α-Fe{sub 2}O{sub 3}) p-n junction photoanodes synthesized from in situ doping of nickel (Ni) during cathodic electrodeposition of hematite were successfully demonstrated. A postulation model was proposed to explain the fundamental mechanism of Ni{sup 2+} ions involved, and the eventual formation of NiO on the subsurface region of hematite that enhanced the potential photoelectrochemical water oxidation process. Through this study, it was found that the measured photocurrent densities of the Ni-doped hematite photoanodes were highly dependent on the concentrations of Ni dopant used. The optimum Ni dopant at 25 M% demonstrated an excellent photoelectrochemical performance of 7-folds enhancement as compared to bare hematite photoanode. This was attributed to the increased electron donor density through the p-n junction and thus lowering the energetic barrier for water oxidation activity at the optimum Ni dopant concentration. Concurrently, the in situ Ni-doping of hematite has also lowered the photogenerated charge carrier transfer resistance as measured using the electrochemical impedance spectroscopy. It is expected that the fundamental understanding gained through this study is helpful for the rational design and construction of highly efficient photoanodes for application in photoelectrochemical process.

  16. In situ Ni-doping during cathodic electrodeposition of hematite for excellent photoelectrochemical performance of nanostructured nickel oxide-hematite p-n junction photoanode

    International Nuclear Information System (INIS)

    Phuan, Yi Wen; Ibrahim, Elyas; Chong, Meng Nan; Zhu, Tao; Lee, Byeong-Kyu; Ocon, Joey D.; Chan, Eng Seng

    2017-01-01

    Highlights: • NiO-hematite p-n junction photoanodes were fabricated via an in situ Ni-doping. • The fundamental mechanism of Ni"2"+ ions involved was elucidated. • The optimum Ni dopant was 25 M% for the highest photocurrent density. • It exhibited an excellent photoelectrochemical performance of 7-folds enhancement. - Abstract: Nanostructured nickel oxide-hematite (NiO/α-Fe_2O_3) p-n junction photoanodes synthesized from in situ doping of nickel (Ni) during cathodic electrodeposition of hematite were successfully demonstrated. A postulation model was proposed to explain the fundamental mechanism of Ni"2"+ ions involved, and the eventual formation of NiO on the subsurface region of hematite that enhanced the potential photoelectrochemical water oxidation process. Through this study, it was found that the measured photocurrent densities of the Ni-doped hematite photoanodes were highly dependent on the concentrations of Ni dopant used. The optimum Ni dopant at 25 M% demonstrated an excellent photoelectrochemical performance of 7-folds enhancement as compared to bare hematite photoanode. This was attributed to the increased electron donor density through the p-n junction and thus lowering the energetic barrier for water oxidation activity at the optimum Ni dopant concentration. Concurrently, the in situ Ni-doping of hematite has also lowered the photogenerated charge carrier transfer resistance as measured using the electrochemical impedance spectroscopy. It is expected that the fundamental understanding gained through this study is helpful for the rational design and construction of highly efficient photoanodes for application in photoelectrochemical process.

  17. Cytochrome c interaction with hematite ({alpha}-Fe{sub 2}O{sub 3}) surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Eggleston, Carrick M. [Department of Geology and Geophysics, University of Wyoming, Laramie, WY 82071 (United States)]. E-mail: carrick@uwyo.edu; Khare, Nidhi [Department of Geology and Geophysics, University of Wyoming, Laramie, WY 82071 (United States); Lovelace, David M. [Department of Geology and Geophysics, University of Wyoming, Laramie, WY 82071 (United States)

    2006-02-15

    The interaction of metalloproteins such as cytochromes with oxides is of interest for a number of reasons, including molecular catalysis of environmentally important mineral-solution electron transfer reactions (e.g., dehalogenations) and photovoltaic applications. Iron reduction by bacteria, thought to be cytochrome mediated, is of interest for geochemical and environmental remediation reasons. As a baseline for understanding cytochrome interaction with ferric oxide surfaces, we report on the interaction of mitochondrial cytochrome c (Mcc), a well-studied protein, with hematite ({alpha}-Fe{sub 2}O{sub 3}) surfaces. Mcc sorbs strongly to hematite from aqueous solution in a narrow pH range corresponding to opposite charge on Mcc and hematite (between pH 8.5 and 10, Mcc is positively charged and hematite surfaces are negatively charged). Cyclic voltammetry of Mcc using hematite electrodes gives redox potentials characteristic of Mcc in a native conformational state, with no evidence for unfolding on the hematite surface. Atomic force microscopy imaging is consistent with a loosely attached adsorbate that is easily deformed by the AFM tip. In phosphate-containing solution, Mcc adhers to the surface more strongly. These results establish hematite as a viable material for electrochemical and spectroscopic characterization of cytochrome-mineral interaction.

  18. Control of Earth-like magnetic fields on the transformation of ferrihydrite to hematite and goethite.

    Science.gov (United States)

    Jiang, Zhaoxia; Liu, Qingsong; Dekkers, Mark J; Barrón, Vidal; Torrent, José; Roberts, Andrew P

    2016-07-26

    Hematite and goethite are the two most abundant iron oxides in natural environments. Their formation is controlled by multiple environmental factors; therefore, their relative concentration has been used widely to indicate climatic variations. In this study, we aimed to test whether hematite and goethite growth is influenced by ambient magnetic fields of Earth-like values. Ferrihydrite was aged at 95 °C in magnetic fields ranging from ~0 to ~100 μT. Our results indicate a large influence of the applied magnetic field on hematite and goethite growth from ferrihydrite. The synthesized products are a mixture of hematite and goethite for field intensities fields favour hematite formation by accelerating ferrimagnetic ferrihydrite aggregation. Additionally, hematite particles growing in a controlled magnetic field of ~100 μT appear to be arranged in chains, which may be reduced to magnetite keeping its original configuration, therefore, the presence of magnetic particles in chains in natural sediments cannot be used as an exclusive indicator of biogenic magnetite. Hematite vs. goethite formation in our experiments is influenced by field intensity values within the range of geomagnetic field variability. Thus, geomagnetic field intensity could be a source of variation when using iron (oxyhydr-)oxide concentrations in environmental magnetism.

  19. Impact of environmental conditions on aggregation kinetics of hematite and goethite nanoparticles

    International Nuclear Information System (INIS)

    Xu, Chen-yang; Deng, Kai-ying; Li, Jiu-yu; Xu, Ren-kou

    2015-01-01

    Hematite and goethite nanoparticles were used as model minerals to investigate their aggregation kinetics under soil environmental conditions in the present study. The hydrodynamic diameters of hematite and goethite nanoparticles were 34.4 and 66.3 nm, respectively. The positive surface charges and zeta potential values for goethite were higher than for hematite. The effective diameter for goethite was much larger than for hematite due to anisotropic sticking of needle-shaped goethite during aggregation. Moreover, the critical coagulation concentration (CCC) values of nanoparticles in solutions of NaNO 3 , NaCl, NaF, and Na 2 SO 4 were 79.2, 75.0, 7.8, and 0.5 mM for hematite and they were 54.7, 62.6, 5.5, and 0.2 mM for goethite, respectively. The disparity of anions in inducing hematite or goethite aggregation lay in the differences in interfacial interactions. NO 3 − and Cl − could decrease the zeta potential and enhance aggregation mainly through increasing ionic strength and compressing electric double layers of hematite and goethite nanoparticles. F − and SO 4 2− highly destabilized the suspensions of nanoparticles mainly through specific adsorption and then neutralizing the positive surface charges of nanoparticles. Specific adsorption of cations could increase positive surface charges and stabilize hematite and goethite nanoparticles. The Hamaker constants of hematite and goethite nanoparticles were calculated to be 2.87 × 10 −20 and 2.29 × 10 −20 J −1 , respectively. The predicted CCC values based on DLVO theory were consistent well with the experimentally determined CCC values in NaNO 3 , NaCl, NaF, and Na 2 SO 4 systems, which demonstrated that DLVO theory could successfully predict the aggregation kinetics even when specific adsorption of ions occurred

  20. In-situ deposition of hematite (α-Fe2O3) microcubes on cotton cellulose via hydrothermal method

    Science.gov (United States)

    Gili, M.; Latag, G.; Balela, M.

    2018-03-01

    Hematite microcubes with truncated edges have been successfully deposited on cotton cellulose via one-step hydrothermal process using anhydrous FeCl3 and glycine as Fe(III) precursor and chelating agent, respectively. The amount of glycine significantly affects the morphology and yield of hematite. The addition of 0.495 g of glycine to 50 ml of 0.1 M FeCl3 solution with 0.400 g of cotton resulted to hematite-deposited cellulose having ∼15% hematite content. The reduction of glycine to 0.247 g increased the amount of hematite on the surface of the cotton cellulose to ∼20% by weight. However, the hematite microcubes have a wide size distribution, with particle size in the range of 0.684 μm to 1.520 μm. Without glycine, hematite cannot be formed in the solution.

  1. Utah Marbles and Mars Blueberries: Comparitive Terrestrial Analogs for Hematite Concretions on Mars

    Science.gov (United States)

    Chan, M. A.; Beitler, B.; Parry, W. T.; Ormö, J.; Komatsu, G.

    2005-03-01

    Compelling comparisons show why Utah iron oxide-cemented "marbles" are a good analog for Mars hematite "blueberries". Terrestrial examples offer valuable models for interpreting the diagenetic history and importance of water on Mars.

  2. Design, Fabrication, and Characterization of Hematite (α-Fe2O3) Nanostructures

    Science.gov (United States)

    Jansi Rani, B.; Mageswari, R.; Ravi, G.; Ganesh, V.; Yuvakkumar, R.

    2017-12-01

    The influence of processing parameters on the physicochemical properties of hematite α-Fe2O3 nanostructures was investigated. X-ray diffraction results revealed the hematite phase rhombohedral structure. Scanning electron microscope results explored nanospheres, nanohexagonal platelets, nanoellipsoids, distorted nanocubes, and interconnected platelets nanostructures. Rhombohedral single-phase hematite was confirmed through five Raman active modes. 2 P 3/2 (1) → 2 P 1/2 transition in photoluminescence spectra and Fourier-transform infrared spectroscopy band observed at 555 cm-1 revealed the hematite formation. The highest specific capacitance value of 151.09 F/g for scan rate of 10 mV/s was obtained for the hydrothermal-assisted product using an Fe(NO3)2·9H2O precursor in KOH electrolyte solutions.

  3. Efficient removal of trace antimony(III) through adsorption by hematite modified magnetic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Shan, Chao; Ma, Zhiyao; Tong, Meiping, E-mail: tongmeiping@pku.edu.cn

    2014-03-01

    Graphical abstract: - Highlights: • Sb(III) adsorption capacity of MNP@hematite was twice that of commercial Fe{sub 3}O{sub 4}. • pH, ionic strength, coexisting anions and NOM did not inhibit Sb(III) removal. • MNP@hematite could remove trace Sb(III) and As(III) from water simultaneously. • Efficient removal of Sb(III) from real tap water was achieved. • MNP@hematite could be easily recycled with a magnet and could be used repeatedly. - Abstract: Hematite coated magnetic nanoparticle (MNP@hematite) was fabricated through heterogeneous nucleation technique and used to remove trace Sb(III) from water. Powder X-ray diffraction, transmission electron microscopy (TEM), and alternating gradient magnetometry were utilized to characterize the prepared adsorbent. TEM image showed that MNP@hematite particles were spherical with size of 10–30 nm. With saturation magnetization of 27.0 emu/g, MNP@hematite particles could be easily separated from water with a simple magnetic process in short time (5 min). At initial concentration of 110 μg/L, Sb(III) was rapidly decreased to below 5 μg/L by MNP@hematite in 10 min. Sb(III) adsorption capacity of MNP@hematite was 36.7 mg/g, which was almost twice that of commercial Fe{sub 3}O{sub 4} nanoparticles. The removal of trace Sb(III) was not obviously affected by solution pH (over a wide range from 3 to 11), ionic strength (up to 100 mM), coexisting anions (chloride, nitrate, sulfate, carbonate, silicate, and phosphate, up to 10 mM) and natural organic matters (humic acid and alginate, up to 8 mg/L as TOC). Moreover, MNP@hematite particles were able to remove Sb(III) and As(III) simultaneously. Trace Sb(III) could also be effectively removed from real tap water by MNP@hematite. The magnetic adsorbent could be recycled and used repeatedly.

  4. Efficient removal of trace antimony(III) through adsorption by hematite modified magnetic nanoparticles

    International Nuclear Information System (INIS)

    Shan, Chao; Ma, Zhiyao; Tong, Meiping

    2014-01-01

    Graphical abstract: - Highlights: • Sb(III) adsorption capacity of MNP@hematite was twice that of commercial Fe 3 O 4 . • pH, ionic strength, coexisting anions and NOM did not inhibit Sb(III) removal. • MNP@hematite could remove trace Sb(III) and As(III) from water simultaneously. • Efficient removal of Sb(III) from real tap water was achieved. • MNP@hematite could be easily recycled with a magnet and could be used repeatedly. - Abstract: Hematite coated magnetic nanoparticle (MNP@hematite) was fabricated through heterogeneous nucleation technique and used to remove trace Sb(III) from water. Powder X-ray diffraction, transmission electron microscopy (TEM), and alternating gradient magnetometry were utilized to characterize the prepared adsorbent. TEM image showed that MNP@hematite particles were spherical with size of 10–30 nm. With saturation magnetization of 27.0 emu/g, MNP@hematite particles could be easily separated from water with a simple magnetic process in short time (5 min). At initial concentration of 110 μg/L, Sb(III) was rapidly decreased to below 5 μg/L by MNP@hematite in 10 min. Sb(III) adsorption capacity of MNP@hematite was 36.7 mg/g, which was almost twice that of commercial Fe 3 O 4 nanoparticles. The removal of trace Sb(III) was not obviously affected by solution pH (over a wide range from 3 to 11), ionic strength (up to 100 mM), coexisting anions (chloride, nitrate, sulfate, carbonate, silicate, and phosphate, up to 10 mM) and natural organic matters (humic acid and alginate, up to 8 mg/L as TOC). Moreover, MNP@hematite particles were able to remove Sb(III) and As(III) simultaneously. Trace Sb(III) could also be effectively removed from real tap water by MNP@hematite. The magnetic adsorbent could be recycled and used repeatedly

  5. Termomagnetic investigations influence coal and organic carbon on transformation structure of hematite to magnetite

    Directory of Open Access Journals (Sweden)

    Dudchenko N.O.

    2014-12-01

    Full Text Available Thermomagnetic investigations of hematite into magnetite transformations by activated carbon and starch were carried-out using laboratory facility, that allows automatic registration of sample magnetization with the temperature (the rate of sample heating/cooling was 65-80°/min. It was shown, that reduction of hematite by starch occurs by the temperatures up to 650°С and leads to formation of magnetic material with saturation magnetization ~50 А*m2/kg. Reduction of hematite by activated coal in the same temperature range leads to formation of the product with saturation magnetization ~0,5 А*m2/kg. The problem of the development and introduction of new energy-efficient methods of enriching these types of iron ore, which can significantly increase the profitability of using oxidized iron ore in the creation of iron ore and iron ore solve the environmental problems of the regions. Thermomagnetic curves have received in magnetic hematite transformation product using as a reducing agent activated carbon ZL-302 and compare it with starch, proposed a method developed by us. It is shown that reduction of hematite to magnetite using coal ZL-302 is at a much higher temperature compared to starch. Recovery hematite by starch in the temperature range 400 ° -650 ° C results in a product with magnetization ~ 50 A * m2 / kg. Restoration of charcoal hematite in the same temperature range results in a product with magnetization ~ 0.5 A * m2 / kg, and when heated to 800 ° C magnetization increases to ~ 10 * m2 / kg. Thus, hematite ores starch recovery is less energy that can be used to develop new ways to get iron ore concentrates.

  6. Strontium-Doped Hematite as a Possible Humidity Sensing Material for Soil Water Content Determination

    OpenAIRE

    Tulliani, Jean-Marc; Baroni, Chiara; Zavattaro, Laura; Grignani, Carlo

    2013-01-01

    The aim of this work is to study the sensing behavior of Sr-doped hematite for soil water content measurement. The material was prepared by solid state reaction from commercial hematite and strontium carbonate heat treated at 900 °C. X-Ray diffraction, scanning electron microscopy and mercury intrusion porosimetry were used for microstructural characterization of the synthesized powder. Sensors were then prepared by uniaxially pressing and by screen-printing, on an alumina substrate, the prep...

  7. Microbially induced separation of quartz from hematite using sulfate reducing bacteria.

    Science.gov (United States)

    Prakasan, M R Sabari; Natarajan, K A

    2010-07-01

    Cells and metabolic products of Desulfovibrio desulfuricans were successfully used to separate quartz from hematite through environmentally benign microbially induced flotation. Bacterial metabolic products such as extracellular proteins and polysaccharides were isolated from both unadapted and mineral-adapted bacterial metabolite and their basic characteristics were studied in order to get insight into the changes brought about on bioreagents during adaptation. Interaction between bacterial cells and metabolites with minerals like hematite and quartz brought about significant surface-chemical changes on both the minerals. Quartz was rendered more hydrophobic, while hematite became more hydrophilic after biotreatment. The predominance of bacterial polysaccharides on interacted hematite and of proteins on quartz was responsible for the above surface-chemical changes, as attested through adsorption studies. Surface-chemical changes were also observed on bacterial cells after adaptation to the above minerals. Selective separation of quartz from hematite was achieved through interaction with quartz-adapted bacterial cells and metabolite. Mineral-specific proteins secreted by quartz-adapted cells were responsible for conferment of hydrophobicity on quartz resulting in enhanced separation from hematite through flotation. 2010 Elsevier B.V. All rights reserved.

  8. Solution chemistry of carbonate minerals and its effects on the flotation of hematite with sodium oleate

    Science.gov (United States)

    Li, Dong; Yin, Wan-zhong; Xue, Ji-wei; Yao, Jin; Fu, Ya-feng; Liu, Qi

    2017-07-01

    The effects of carbonate minerals (dolomite and siderite) on the flotation of hematite using sodium oleate as a collector were investigated through flotation tests, supplemented by dissolution measurements, solution chemistry calculations, zeta-potential measurements, Fourier transform infrared (FTIR) spectroscopic studies, and X-ray photoelectron spectroscopy (XPS) analyses. The results of flotation tests show that the presence of siderite or dolomite reduced the recovery of hematite and that the inhibiting effects of dolomite were stronger. Dissolution measurements, solution chemistry calculations, and flotation tests confirmed that both the cations (Ca2+ and Mg2+) and CO3 2- ions dissolved from dolomite depressed hematite flotation, whereas only the CO3 2- ions dissolved from siderite were responsible for hematite depression. The zeta-potential, FTIR spectroscopic, and XPS analyses indicated that Ca2+, Mg2+, and CO3 2- (HCO3 -) could adsorb onto the hematite surface, thereby hindering the adsorption of sodium oleate, which was the main reason for the inhibiting effects of carbonate minerals on hematite flotation.

  9. Use of interfacial layers to prolong hole lifetimes in hematite probed by ultrafast transient absorption spectroscopy

    Science.gov (United States)

    Paradzah, Alexander T.; Diale, Mmantsae; Maabong, Kelebogile; Krüger, Tjaart P. J.

    2018-04-01

    Hematite is a widely investigated material for applications in solar water oxidation due primarily to its small bandgap. However, full realization of the material continues to be hampered by fast electron-hole recombination rates among other weaknesses such as low hole mobility, short hole diffusion length and low conductivity. To address the problem of fast electron-hole recombination, researchers have resorted to growth of nano-structured hematite, doping and use of under-layers. Under-layer materials enhance the photo-current by minimising electron-hole recombination through suppressing of back electron flow from the substrate, such as fluorine-doped tin oxide (FTO), to hematite. We have carried out ultrafast transient absorption spectroscopy on hematite in which Nb2O5 and SnO2 materials were used as interfacial layers to enhance hole lifetimes. The transient absorption data was fit with four different lifetimes ranging from a few hundred femtoseconds to a few nanoseconds. We show that the electron-hole recombination is slower in samples where interfacial layers are used than in pristine hematite. We also develop a model through target analysis to illustrate the effect of under-layers on electron-hole recombination rates in hematite thin films.

  10. Oxygen vacancy doping of hematite analyzed by electrical conductivity and thermoelectric power measurements

    Science.gov (United States)

    Mock, Jan; Klingebiel, Benjamin; Köhler, Florian; Nuys, Maurice; Flohre, Jan; Muthmann, Stefan; Kirchartz, Thomas; Carius, Reinhard

    2017-11-01

    Hematite (α -F e2O3 ) is known for poor electronic transport properties, which are the main drawback of this material for optoelectronic applications. In this study, we investigate the concept of enhancing electrical conductivity by the introduction of oxygen vacancies during temperature treatment under low oxygen partial pressure. We demonstrate the possibility of tuning the conductivity continuously by more than five orders of magnitude during stepwise annealing in a moderate temperature range between 300 and 620 K. With thermoelectric power measurements, we are able to attribute the improvement of the electrical conductivity to an enhanced charge-carrier density by more than three orders of magnitude. We compare the oxygen vacancy doping of hematite thin films with hematite nanoparticle layers. Thereby we show that the dominant potential barrier that limits charge transport is either due to grain boundaries in hematite thin films or due to potential barriers that occur at the contact area between the nanoparticles, rather than the potential barrier within the small polaron hopping model, which is usually applied for hematite. Furthermore, we discuss the transition from oxygen-deficient hematite α -F e2O3 -x towards the magnetite F e3O4 phase of iron oxide at high density of vacancies.

  11. Hydrogen Reduction of Hematite Ore Fines to Magnetite Ore Fines at Low Temperatures

    Directory of Open Access Journals (Sweden)

    Wenguang Du

    2017-01-01

    Full Text Available Surplus coke oven gases (COGs and low grade hematite ores are abundant in Shanxi, China. Our group proposes a new process that could simultaneously enrich CH4 from COG and produce separated magnetite from low grade hematite. In this work, low-temperature hydrogen reduction of hematite ore fines was performed in a fixed-bed reactor with a stirring apparatus, and a laboratory Davis magnetic tube was used for the magnetic separation of the resulting magnetite ore fines. The properties of the raw hematite ore, reduced products, and magnetic concentrate were analyzed and characterized by a chemical analysis method, X-ray diffraction, optical microscopy, and scanning electron microscopy. The experimental results indicated that, at temperatures lower than 400°C, the rate of reduction of the hematite ore fines was controlled by the interfacial reaction on the core surface. However, at temperatures higher than 450°C, the reaction was controlled by product layer diffusion. With increasing reduction temperature, the average utilization of hydrogen initially increased and tended to a constant value thereafter. The conversion of Fe2O3 in the hematite ore played an important role in the total iron recovery and grade of the concentrate. The grade of the concentrate decreased, whereas the total iron recovery increased with the increasing Fe2O3 conversion.

  12. Sorption of 241Am onto montmorillonite, illite and hematite colloids

    International Nuclear Information System (INIS)

    Degueldre, C.; Ulrich, H.J.; Silby, H.

    1994-01-01

    Actinide sorption on colloids may be described as a competition between the formation of complexes in solution and the build up of surface complexes. The role of particle and of carbonate concentrations on the sorption/desorption of 241 Am on montmorillonite, illite and hematite colloids is investigated. Since the partition coefficient (K p ) values are virtually independent of the colloid concentrations, within the range 1 to 300 ppm, no significant aggregation takes place in the sorption/desorption experiment. At pH 8, a slight decrease of K p is observed if the concentration of total carbonate exceeds 10 -2 M. The formation of the carbonato- (and hydroxo-carbonato-) complexes in the solution competes with the formation of surface complexes on the colloids. A relationship between the sorption coefficient and the complexation of 241 Am in the solution has been found. This leads to the conclusion that, besides free americium cation, the hydroxo-, and carbonato- as well as the mixed hydroxo-carbonato-complexes are sorbed. Only when the tricarbonatocomplex [Am(CO 3 ) 3 ] 3- prevails (total carbonate concentration > 10 -2 M), a significant decrease of the distribution coefficient is observed. At pH 10 this decrease disappears because under these conditions the strong hydroxo-complexes dominate. A pragmatic and relatively simple application of surface complexation model describes the observed features. (orig.)

  13. Probing size-dependent electrokinetics of hematite aggregates

    Energy Technology Data Exchange (ETDEWEB)

    Kedra-Królik, Karolina; Rosso, Kevin M.; Zarzycki, Piotr

    2017-02-01

    Aqueous particle suspensions of many kinds are stabilized by the electrostatic potential developed at their surfaces from reaction with water and ions. An important and less well understood aspect of this stabilization is the dependence of the electrostatic surface potential on particle size. Surface electrostatics are typically probed by measuring particle electrophoretic mobilities and quantified in the electrokinetic potential (f), using commercially available Zeta Potential Analyzers (ZPA). Even though ZPAs provide frequency-spectra (histograms) of electrophoretic mobility and hydrodynamic diameter, typically only the maximal-intensity values are reported, despite the information in the remainder of the spectra. Here we propose a mapping procedure that inter-correlates these histograms to extract additional insight, in this case to probe particle size-dependent electrokinetics. Our method is illustrated for a suspension of prototypical iron (III) oxide (hematite, a-Fe2O3). We found that the electrophoretic mobility and f-potential are a linear function of the aggregate size. By analyzing the distribution of surface site types as a function of aggregate size we show that site coordination increases with increasing aggregate diameter. This observation explains why the acidity of the iron oxide particles decreases with increasing particle size.

  14. Kinetics of Photoelectrochemical Oxidation of Methanol on Hematite Photoanodes

    Science.gov (United States)

    2017-01-01

    The kinetics of photoelectrochemical (PEC) oxidation of methanol, as a model organic substrate, on α-Fe2O3 photoanodes are studied using photoinduced absorption spectroscopy and transient photocurrent measurements. Methanol is oxidized on α-Fe2O3 to formaldehyde with near unity Faradaic efficiency. A rate law analysis under quasi-steady-state conditions of PEC methanol oxidation indicates that rate of reaction is second order in the density of surface holes on hematite and independent of the applied potential. Analogous data on anatase TiO2 photoanodes indicate similar second-order kinetics for methanol oxidation with a second-order rate constant 2 orders of magnitude higher than that on α-Fe2O3. Kinetic isotope effect studies determine that the rate constant for methanol oxidation on α-Fe2O3 is retarded ∼20-fold by H/D substitution. Employing these data, we propose a mechanism for methanol oxidation under 1 sun irradiation on these metal oxide surfaces and discuss the implications for the efficient PEC methanol oxidation to formaldehyde and concomitant hydrogen evolution. PMID:28735533

  15. Potential-specific structure at the hematite-electrolyte interface

    Energy Technology Data Exchange (ETDEWEB)

    McBriarty, Martin E.; Stubbs, Joanne; Eng, Peter; Rosso, Kevin M.

    2018-02-21

    The atomic-scale structure of interfaces between metal oxides and aqueous electrolytes controls their catalytic, geochemical, and corrosion behavior. Measurements that probe these interfaces in situ provide important details of ion and solvent arrangements, but atomically precise structural models do not exist for common oxide-electrolyte interfaces far from equilibrium. Using a novel cell, we measured the structure of the hematite (a-Fe2O3) (110$\\bar{2}$)-electrolyte interface under controlled electrochemical bias using synchrotron crystal truncation rod X ray scattering. At increasingly cathodic potentials, charge-compensating protonation of surface oxygen groups increases the coverage of specifically bound water while adjacent water layers displace outwardly and became disordered. Returning to open circuit potential leaves the surface in a persistent metastable protonation state. The flux of current and ions at applied potential is thus regulated by a unique interfacial electrolyte environment, suggesting that electrical double layer models should be adapted to the dynamically changing interfacial structure far from equilibrium.

  16. Mapping the metal uptake in plants from Jasper Ridge Biological Preserve using synchrotron micro-focused X-ray fluorescence spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lo, Allison [Univ. of California, Davis, CA (United States)

    2015-08-20

    Serpentine soil originates in the Earth’s mantle and contains high concentrations of potentially toxic transition metals. Although serpentine soil limits plant growth, endemic and adapted plants at Jasper Ridge Biological Preserve, located behind SLAC National Accelerator Laboratory, can tolerate these conditions. Serpentine soil and seeds belonging to native California and invasive plants were collected at Jasper Ridge. The seeds were grown hydroponically and on serpentine and potting soil to examine the uptake and distribution of ions in the roots and shoots using synchrotron micro-focused X-ray fluorescence spectroscopy. The results were used to determine differences between serpentine-tolerant plants. Rye grown on potting soil was enriched in Ni, Fe, Mn, and Cr compared to purple needlegrass grown on serpentine soil. Serpentine vegetation equally suppressed the uptake of Mn, Ni, and Fe in the roots and shoots. The uptake of Ca and Mg affected the uptake of other elements such as K, S, and P.

  17. Vulnerability assessment of skiing-dependent businesses to the effects of climate change in Banff and Jasper National Parks, Canada

    Science.gov (United States)

    Reynolds, David Michael

    This qualitative study examines the potential positive and negative socio-economic impacts that may emerge from the long-term effects of climate change on skiing-dependent businesses in Banff and Jasper National Parks, Canada. My goal was to determine whether or not skiing-related tourism in the parks in the 2020s and 2050s is more or less socio-economically vulnerable to the effects of climate change on snow cover, temperatures and ski season length at ski resorts in the parks. My study explored the level of awareness and personal perceptions of 60 skiing-dependent business managers about how the impact of climate change on ski resorts may influence future socio-economics of ski tourism businesses. I employed a vulnerability assessment approach and adopted some elements of grounded theory. My primary data sources are interviews with managers and the outcome of the geographical factors index (GFI). Supporting methods include: an analysis and interpretation of climate model data and an interpretation of the economic analysis of skiing in the parks. The interview data were sorted and coded to establish concepts and findings by interview questions, while the GFI model rated and ranked 24 regional ski resorts in the Canadian Cordillera. The findings answered the research questions and helped me conclude what the future socio-economic vulnerability may be of skiing-dependent businesses in the parks. The interviews revealed that managers are not informed about climate change and they have not seen any urgency to consider the effects on business. The GFI revealed that the ski resorts in the parks ranked in the top ten of 24 ski resorts in the Cordillera based on 14 common geographical factors. The economic reports suggest skiing is the foundation of the winter economy in the parks and any impact on skiing would directly impact other skiing-dependent businesses. Research indicates that the effects of climate change may have less economic impact on skiing

  18. Impact of environmental conditions on aggregation kinetics of hematite and goethite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Chen-yang, E-mail: cyxu@issas.ac.cn; Deng, Kai-ying; Li, Jiu-yu, E-mail: jyli@issas.ac.cn; Xu, Ren-kou, E-mail: rkxu@issas.ac.cn [Chinese Academy of Sciences, State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science (China)

    2015-10-15

    Hematite and goethite nanoparticles were used as model minerals to investigate their aggregation kinetics under soil environmental conditions in the present study. The hydrodynamic diameters of hematite and goethite nanoparticles were 34.4 and 66.3 nm, respectively. The positive surface charges and zeta potential values for goethite were higher than for hematite. The effective diameter for goethite was much larger than for hematite due to anisotropic sticking of needle-shaped goethite during aggregation. Moreover, the critical coagulation concentration (CCC) values of nanoparticles in solutions of NaNO{sub 3}, NaCl, NaF, and Na{sub 2}SO{sub 4} were 79.2, 75.0, 7.8, and 0.5 mM for hematite and they were 54.7, 62.6, 5.5, and 0.2 mM for goethite, respectively. The disparity of anions in inducing hematite or goethite aggregation lay in the differences in interfacial interactions. NO{sub 3}{sup −} and Cl{sup −} could decrease the zeta potential and enhance aggregation mainly through increasing ionic strength and compressing electric double layers of hematite and goethite nanoparticles. F{sup −} and SO{sub 4}{sup 2−} highly destabilized the suspensions of nanoparticles mainly through specific adsorption and then neutralizing the positive surface charges of nanoparticles. Specific adsorption of cations could increase positive surface charges and stabilize hematite and goethite nanoparticles. The Hamaker constants of hematite and goethite nanoparticles were calculated to be 2.87 × 10{sup −20} and 2.29 × 10{sup −20} J{sup −1}, respectively. The predicted CCC values based on DLVO theory were consistent well with the experimentally determined CCC values in NaNO{sub 3}, NaCl, NaF, and Na{sub 2}SO{sub 4} systems, which demonstrated that DLVO theory could successfully predict the aggregation kinetics even when specific adsorption of ions occurred.

  19. Utilization of natural hematite as reactive barrier for immobilization of radionuclides from radioactive liquid waste.

    Science.gov (United States)

    El Afifi, E M; Attallah, M F; Borai, E H

    2016-01-01

    Potential utilization of hematite as a natural material for immobilization of long-lived radionuclides from radioactive liquid waste was investigated. Hematite ore has been characterized by different analytical tools such as Fourier transformer infrared (FTIR), X-ray fluorescence (XRF), powder X-ray diffraction (XRD), thermogravimetry (TG) and differential thermal (DT) analysis, scanning electron microscopy (SEM) and BET-surface area. In this study, europium was used as REEs(III) and as a homolog of Am(III)-isotopes (such as (241)Am of 432.6 y, (242m)Am of 141 y and (243)Am of 7370 y). Micro particles of the hematite ore were used for treatment of radioactive waste containing (152+154)Eu(III). The results indicated that 96% (4.1 × 10(4) Bq) of (152+154)Eu(III) was efficiently retained onto hematite ore. Kinetic experiments indicated that the processes could be simulated by a pseudo-second-order model and suggested that the process may be chemisorption in nature. The applicability of Langmuir, Freundlich and Temkin models was investigated. It was found that Langmuir isotherm exhibited the best fit with the experimental results. It can be concluded that hematite is an economic and efficient reactive barrier for immobilization of long-lived radio isotopes of actinides and REEs(III). Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Synthesis, exploration of energy storage and electrochemical sensing properties of hematite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ramasami, Alamelu K. [Centre for Nano and Material Sciences, Jain University, Bangalore 562112 (India); Department of Physics, Advanced Batteries Lab, National University of Singapore, 117542 (Singapore); Ravishankar, T.N.; Sureshkumar, K. [Centre for Nano and Material Sciences, Jain University, Bangalore 562112 (India); Reddy, M.V.; Chowdari, B.V.R. [Department of Physics, Advanced Batteries Lab, National University of Singapore, 117542 (Singapore); Ramakrishnappa, T. [Centre for Nano and Material Sciences, Jain University, Bangalore 562112 (India); Balakrishna, Geetha R., E-mail: br.geetha@jainuniversity.ac.in [Centre for Nano and Material Sciences, Jain University, Bangalore 562112 (India)

    2016-06-25

    Gel-combustion, solution combustion and molten salt methods were used to synthesize hematite nanoparicles. Two weight ratios of precursor (Ferric nitrate) to fuel (Cassava Starch) (1:0.5, 1:1) were used in gel-combustion technique. Ferric nitrate as a precursor and ethylenediamine tetraacetic acid as fuel (in stoichiometric proportions) were used in the solution combustion method. Ferric oxalate was the precursor in molten salt method. The structural parameters of the hematite nanoparticles were studied by X-ray diffraction. The optical properties, including band gap studies were done by UV–Visible spectroscopy. The morphological studies were carried out by Scanning Electron Microscope. The energy storage capacity of the molten salt method-hematite nanoparticles surpassed (920 mAhg{sup −1}) the others while the equal-weight- ratio-hematite nanoparticles synthesized by gel-combustion method exhibited better dopamine sensor properties. - Highlights: • Hematite nanoparticles were synthesized by gel, solution combustion and molten salt methods. • Gel-combustion involved the use of natural fuel extracted from the root tubers of Manihot esculenta. • Two ratios of fuel to precursors were attempted in gel combustion method. • The product formed from the equal weight ratio of fuel to precursor was a very good electrochemical dopamine sensor. • The product formed by molten salt method exhibited good battery behaviour (Li-ion battery).

  1. Synthesis, exploration of energy storage and electrochemical sensing properties of hematite nanoparticles

    International Nuclear Information System (INIS)

    Ramasami, Alamelu K.; Ravishankar, T.N.; Sureshkumar, K.; Reddy, M.V.; Chowdari, B.V.R.; Ramakrishnappa, T.; Balakrishna, Geetha R.

    2016-01-01

    Gel-combustion, solution combustion and molten salt methods were used to synthesize hematite nanoparicles. Two weight ratios of precursor (Ferric nitrate) to fuel (Cassava Starch) (1:0.5, 1:1) were used in gel-combustion technique. Ferric nitrate as a precursor and ethylenediamine tetraacetic acid as fuel (in stoichiometric proportions) were used in the solution combustion method. Ferric oxalate was the precursor in molten salt method. The structural parameters of the hematite nanoparticles were studied by X-ray diffraction. The optical properties, including band gap studies were done by UV–Visible spectroscopy. The morphological studies were carried out by Scanning Electron Microscope. The energy storage capacity of the molten salt method-hematite nanoparticles surpassed (920 mAhg"−"1) the others while the equal-weight- ratio-hematite nanoparticles synthesized by gel-combustion method exhibited better dopamine sensor properties. - Highlights: • Hematite nanoparticles were synthesized by gel, solution combustion and molten salt methods. • Gel-combustion involved the use of natural fuel extracted from the root tubers of Manihot esculenta. • Two ratios of fuel to precursors were attempted in gel combustion method. • The product formed from the equal weight ratio of fuel to precursor was a very good electrochemical dopamine sensor. • The product formed by molten salt method exhibited good battery behaviour (Li-ion battery).

  2. Effects of hematite and ferrihydrite nanoparticles on germination and growth of maize

    Directory of Open Access Journals (Sweden)

    Nicolaza Pariona

    2017-11-01

    Full Text Available Engineered iron oxide nanoparticles (IO-NPs have been used extensively for environmental remediation. It may cause the release IO-NPs to the environment affecting the functions of ecosystems. Plants are an important component of ecosystems and can be used for the evaluation of overall fate, transport and exposure pathways of IO-NPs in the environment. In this work, the effects of engineered ferrihydrite and hematite NPs on the germination and growth of maize are studied. The germination and growth of maize were done with treatments at different concentrations of hematite and ferrihydrite NPs, namely 1, 2, 4, and 6 g/L. Biological indicators of toxicity or stress in maize seedlings were not observed in treatments with engineered hematite and ferrihydrite NPs. In contrast, the NPs treatments increased the growth of maize and the chlorophyll content, except for hematite NPs at 6 g/L, where non-significant effects were found. The translocation of engineered ferrihydrite and hematite NPs in maize stems was demonstrated using confocal laser scanning microscopy.

  3. Establishment of database for Japan Sea parameters on marine environment and radioactivity (JASPER). Volume 2. Radiocarbon and oceanographic properties

    International Nuclear Information System (INIS)

    Otosaka, Shigeyoshi; Suzuki, Takashi; Ito, Toshimichi; Kobayashi, Takuya; Kawamura, Hideyuki; Togawa, Orihiko; Tanaka, Takayuki; Minakawa, Masayuki; Aramaki, Takafumi; Senjyu, Tomoharu

    2010-02-01

    The database for the Japan Sea Parameters on Marine Environment and Radionuclides (JASPER) has been established by the Japan Atomic Energy Agency as a product of the Japan Sea Expeditions. By the previous volume of the database, data for representative anthropogenic radionuclides (strontium-90, cesium-137, and plutonium-239, 240) were opened to public. And now, data for radiocarbon and fundamental oceanographic properties (salinity, temperature, dissolved oxygen) including nutrients (silicate, phosphate, nitrate and nitrite) are released as the second volume of the database. At the beginning of this report (chapter 1), backgrounds, objectives and brief overview of this report are given as an introduction. Then, specifications of this database and methodology in obtaining the concentration data are described in chapter 2. The data stored in the database are presented in tabular and figure forms in chapter 3. Finally, chapter 4 is assigned concluding remarks. In the second version of database, 20,292 data records are stored in the database including 2,695 data for temperature, 2,883 data for salinity, 2,109 data for dissolved oxygen, 11,051 data for the nutrients, and 1,660 data for radiocarbon. The database will be a strong tool for the continuous monitoring for contamination by anthropogenic radionuclides, studies on biogeochemical cycle, and development/validation of models for numerical simulations in the sea. (author)

  4. ISSUES OF LEGITIMIZING POLITICAL POWER IN THE FIRST HALF OF THE TWENTIETH CENTURY: MAX WEBER AND KARL JASPERS

    Directory of Open Access Journals (Sweden)

    Nicolae IUGA

    2012-12-01

    Full Text Available The issue of legitimizing political power has specific dimensions determined by the historical context. In the period following the First World War, democratic regimes dramatically collapsed due to ample protest movements against the political establishment from different countries, but also as a result of a serious political legitimation crisis, thus making way for the rise of totalitarian regimes of Fascism and Nazism. That time debates on the problem of legitimization political power are symptomatic. Due to the general perception regarding corruption in politics and to the political incapacity to deal with social problems, we can witness a decrease of trust in contemporary democratic regimes.In order to exemplify, in a brief expositive manner, my paper will present the topic of political legitimation approached by Max Weber and Karl Jaspers, in a selection of relevant texts issued by both authors during 1919-1931. The aim of this paper is to highlight the actuality, the validity of Weber’s and Jasper’s statements and also their capacity to give pertinent responses to questions such as: What role do the common values play in the legitimating of power in a democratic society? Are there any kinds of limits regarding the electoral legitimation? How can we make the difference between a legitimate appeal and an illegitimate one, between civism and terrorism?

  5. Effect of thermal treatment on solid–solid interface of hematite thin film synthesized by spin-coating deposition solution

    International Nuclear Information System (INIS)

    Bellido-Aguilar, Daniel Angel; Tofanello, Aryane; Souza, Flavio L.; Furini, Leonardo Negri; Constantino, Carlos José Leopoldo

    2016-01-01

    This work describes hematite films prepared by a spin-coating deposition solution (SCDS) method that is a sol–gel method derived technique. Hematite films were prepared at two heat treatment temperatures (500 °C and 800 °C) and the influence of thermal treatment on the photoelectrochemical performance was studied. In addition, since the SCDS method allows an optimal control of stoichiometry and impurity incorporation, hematite films modified with Zn 2+ and Sn 4+ were also prepared. The 800 °C-treated hematite films had a higher wettability and roughness that enabled them to have a better photocatalytic response in comparison with that of 500 °C-treated hematite films. Moreover, modified hematite films demonstrated to have a performance slightly better than that of undoped hematite film as shown in linear sweep voltammetry and chronoamperometry results. Although an improvement in the performance of hematite films was achieved by annealing at higher temperatures and incorporating Zn 2+ or Sn 4+ , the general photocatalytic response of the films was poor. Two plausible hypotheses were discussed related to the (i) dopant segregation at grain boundary, and (ii) poor contact between the hematite and fluorine doped tin oxide layer (from the glass substrate), which was experimentally confirmed by a cross-sectional analysis conducted using scanning electron microscopy (SEM). In fact, additional experiments need to be done in order to improve the hematite deposition and make the SCDS a promise method for industrial application. - Highlights: • High temperature of annealing decreases the hematite adherence and performance. • Zn 2+ and Sn 4+ dopants affected differently the photocurrent onset potentials. • Dopants affected the grain size due to their segregation at grain boundaries.

  6. Effect of thermal treatment on solid–solid interface of hematite thin film synthesized by spin-coating deposition solution

    Energy Technology Data Exchange (ETDEWEB)

    Bellido-Aguilar, Daniel Angel; Tofanello, Aryane [Centro de Ciências Naturais e Humanas (CCNH), Universidade Federal do ABC, Av. dos Estados N°5001, Bangu, Santo André, São Paulo CEP 09210-580 (Brazil); Souza, Flavio L., E-mail: flavio.souza@ufabc.edu.br [Centro de Ciências Naturais e Humanas (CCNH), Universidade Federal do ABC, Av. dos Estados N°5001, Bangu, Santo André, São Paulo CEP 09210-580 (Brazil); Furini, Leonardo Negri; Constantino, Carlos José Leopoldo [Faculdade de Ciências e Tecnologia (FCT), UNESP Univ Estadual Paulista, Presidente Prudente, São Paulo, 19060-900 (Brazil)

    2016-04-01

    This work describes hematite films prepared by a spin-coating deposition solution (SCDS) method that is a sol–gel method derived technique. Hematite films were prepared at two heat treatment temperatures (500 °C and 800 °C) and the influence of thermal treatment on the photoelectrochemical performance was studied. In addition, since the SCDS method allows an optimal control of stoichiometry and impurity incorporation, hematite films modified with Zn{sup 2+} and Sn{sup 4+} were also prepared. The 800 °C-treated hematite films had a higher wettability and roughness that enabled them to have a better photocatalytic response in comparison with that of 500 °C-treated hematite films. Moreover, modified hematite films demonstrated to have a performance slightly better than that of undoped hematite film as shown in linear sweep voltammetry and chronoamperometry results. Although an improvement in the performance of hematite films was achieved by annealing at higher temperatures and incorporating Zn{sup 2+} or Sn{sup 4+}, the general photocatalytic response of the films was poor. Two plausible hypotheses were discussed related to the (i) dopant segregation at grain boundary, and (ii) poor contact between the hematite and fluorine doped tin oxide layer (from the glass substrate), which was experimentally confirmed by a cross-sectional analysis conducted using scanning electron microscopy (SEM). In fact, additional experiments need to be done in order to improve the hematite deposition and make the SCDS a promise method for industrial application. - Highlights: • High temperature of annealing decreases the hematite adherence and performance. • Zn{sup 2+} and Sn{sup 4+} dopants affected differently the photocurrent onset potentials. • Dopants affected the grain size due to their segregation at grain boundaries.

  7. Biogenic magnetite, detrital hematite, and relative paleointensity in Quaternary sediments from the Southwest Iberian Margin

    Science.gov (United States)

    Channell, J. E. T.; Hodell, D. A.; Margari, V.; Skinner, L. C.; Tzedakis, P. C.; Kesler, M. S.

    2013-08-01

    Magnetic properties of late Quaternary sediments on the SW Iberian Margin are dominated by bacterial magnetite, observed by transmission electron microscopy (TEM), with contributions from detrital titanomagnetite and hematite. Reactive hematite, together with low organic matter concentrations and the lack of sulfate reduction, lead to dissimilatory iron reduction and availability of Fe(II) for abundant magnetotactic bacteria. Magnetite grain-size proxies (κARM/κ and ARM/IRM) and S-ratios (sensitive to hematite) vary on stadial/interstadial timescales, contain orbital power, and mimic planktic δ18O. The detrital/biogenic magnetite ratio and hematite concentration are greater during stadials and glacial isotopic stages, reflecting increased detrital (magnetite) input during times of lowered sea level, coinciding with atmospheric conditions favoring hematitic dust supply. Magnetic susceptibility, on the other hand, has a very different response being sensitive to coarse detrital multidomain (MD) magnetite associated with ice-rafted debris (IRD). High susceptibility and/or magnetic grain-size coarsening, mark Heinrich stadials (HS), particularly HS2, HS3, HS4, HS5, HS6 and HS7, as well as older Heinrich-like detrital layers, indicating the sensitivity of this region to fluctuations in the position of the polar front. Relative paleointensity (RPI) records have well-constrained age models based on planktic δ18O correlation to ice-core chronologies, however, they differ from reference records (e.g. PISO) particularly in the vicinity of glacial maxima, mainly due to inefficient normalization of RPI records in intervals of enhanced hematite input.

  8. Magnetite–hematite nanoparticles prepared by green methods for heavy metal ions removal from water

    International Nuclear Information System (INIS)

    Ahmed, M.A.; Ali, S.M.; El-Dek, S.I.; Galal, A.

    2013-01-01

    Graphical abstract: The negatively charged cubic magnetite nanoparticles, prepared by the coprecipitation method in N 2 atmosphere, can adsorb up to 99% of the positively charged toxic heavy metal ions at a proper pH value. -- Highlights: • Mixed magnetite–hematite nanoparticles were synthesized via different routes. • Prepared samples were characterized by XRD, HRTEM, BET and magnetic hysteresis. • The material was employed as a sorbent for removal of some heavy metal ions from water. • The effects of pH and the contact time on the adsorption process were studied and optimized. -- Abstract: Mixed magnetite–hematite nanoparticles were synthesized via different routes such as, coprecipitation in air and N 2 atmosphere, citrate–nitrate, glycine–nitrate and microwave-assisted citrate methods. The prepared samples were characterized by X-ray diffraction (XRD), high resolution transmission electron microscope (HRTEM), BET measurements and magnetic hysteresis. XRD data showed the formation of magnetite–hematite mixture with different compositions according to the synthesis method. The particle size was in the range of 4–52 nm for all the prepared samples. From HRTEM micrographs, it was found that, the synthesis method affects the moropholgy of the prepared samples in terms of crystallinity and porosity. The magnetite–hematite mixture was employed as a sorbent material for removal of some heavy metal ions from water such as lead(II), cadmium(II) and chromium(III). The effects of pH value and the contact time on the adsorption process were studied and optimized in order to obtain the highest possible adsorption efficiency of the magnetite–hematite mixture. The effect of the synthesis method of the magnetite–hematite mixture on the adsorption process was also investigated. It was found that samples prepared by the coprecipitation method had better adsorption efficiency than those prepared by other combustion methods

  9. Molecular dynamics simulation of siderite-hematite-quartz flotation with sodium oleate

    Science.gov (United States)

    Li, Lixia; Hao, Haiqing; Yuan, Zhitao; Liu, Jiongtian

    2017-10-01

    Models of sodium oleate adsorption on siderite, hematite and quartz were investigated by molecular dynamic simulation, respectively. Surface energy was calculated to confirm the cleavage plan of hematite and quartz. Both natural cleavage plane of siderite and calculated plane were used to investigate the flotation of the three minerals. Based on the molecular simulation in solution with water as medium, adsorption quantity and interaction capability of oleate ions on the three minerals indicated that siderite could be collected efficiently by sodium oleate at neutral pH. Results of flotation experiments were further demonstrated by analysis of relative concentration of carbon atoms and oxygen atoms.

  10. Transformation of goethite/ferrihydrite to hematite and maghemite under temperate humid conditions in Denmark

    DEFF Research Database (Denmark)

    Nørnberg, Per; Finster, Kai; Gunnlaugsson, Haraldur Pall

    2012-01-01

    At a number of sandy soil sites in Mid Jutland, Denmark, with iron content of 1-2%, very red spots (Munsell colour: dusky red 10R 3/4) of a few square meters are found. These spots are most likely due to burning events. After the fire ashes raised pH. This dispersed silt and clay size soil...... particles which were then transported with seepage water down into lower soil horizons. These particles contain hematite and maghemite due to influence of the fire. However, a long-standing unresolved question is how hematite and maghemite can also be present along with goethite and ferrihydrite...

  11. Fabrication of non-aging superhydrophobic surfaces by packing flower-like hematite particles

    Science.gov (United States)

    Cao, Anmin; Cao, Liangliang; Gao, Di

    2008-03-01

    We demonstrate the fabrication of non-aging superhydrophobic surfaces by packing flower-like micrometer-sized hematite particles. Although hematite is intrinsically hydrophilic, the nanometer-sized protrusions on the particles form textures with overhanging structures that prevent water from entering into the textures and induce a macroscopic superhydrophobic phenomenon. These superhydrophobic surfaces do not age even in extremely oxidative environments---they retain the superhydrophobicity after being stored in ambient laboratory air for 4 months, heated to 800 degree C in air for 10 hours, and exposed to ultraviolet ozone for 10 hours.

  12. Shape Evolution Synthesis of Monodisperse Spherical, Ellipsoidal, and Elongated Hematite (alpha-Fe2O3) Nanoparticles Using Ascorbic Acid

    NARCIS (Netherlands)

    Tan, W.F.; Yu, Y.T.; Wang, M.X.; Liu, F.; Koopal, L.K.

    2014-01-01

    Spherical, ellipsoidal, and elongated hematite particles have been obtained via a simple chemical precipitation reaction of FeCl3 and NaOH in the presence of ascorbic acid,(AA). The effects of pH, molar ratio of AA/Fe(III), and time on the formation and shape of the hematite particles were

  13. Charge carrier trapping, recombination and transfer in hematite (-Fe2O3) water splitting photoanodes

    NARCIS (Netherlands)

    Barroso Silva da Cruz, M.; Pendlebury, S.R.; Cowan, A.J.; Durrant, J.R.

    2013-01-01

    Hematite is currently considered one of the most promising materials for the conversion and storage of solar energy via the photoelectrolysis of water. Whilst there has been extensive research and much progress in the development of hematite structures with enhanced photoelectrochemical (PEC)

  14. Thermogravimetric Analysis of Modified Hematite by Methane (CH{sub 4}) for Chemical-Looping Combustion: A Global Kinetics Mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Monazam, Esmail R; Breault, Ronald W; Siriwardane, Ranjani; Miller, Duane D

    2013-10-01

    Iron oxide (Fe{sub 2}O{sub 3}) or in its natural form (hematite) is a potential material to capture CO{sub 2} through the chemical-looping combustion (CLC) process. It is known that magnesium (Mg) is an effective methyl cleaving catalyst and as such it has been combined with hematite to assess any possible enhancement to the kinetic rate for the reduction of Fe{sub 2}O{sub 3} with methane. Therefore, in order to evaluate its effectiveness as a hematite additive, the behaviors of Mg-modified hematite samples (hematite –5% Mg(OH){sub 2}) have been analyzed with regard to assessing any enhancement to the kinetic rate process. The Mg-modified hematite was prepared by hydrothermal synthesis. The reactivity experiments were conducted in a thermogravimetric analyzer (TGA) using continuous stream of CH{sub 4} (5, 10, and 20%) at temperatures ranging from 700 to 825 {degrees}C over ten reduction cycles. The mass spectroscopy analysis of product gas indicated the presence of CO{sub 2}, H{sub 2}O, H{sub 2} and CO in the gaseous product. The kinetic data at reduction step obtained by isothermal experiments could be well fitted by two parallel rate equations. The modified hematite samples showed higher reactivity as compared to unmodified hematite samples during reduction at all investigated temperatures.

  15. Paleomagnetism of Jurassic radiolarian chert above the Coast Range ophiolite at Stanley Mountain, California, and implications for its paleogeographic origins

    Science.gov (United States)

    Hagstrum, J.T.; Murchey, B.L.

    1996-01-01

    Upper Jurassic red tuffaceous chert above the Coast Range ophiolite at Stanley Mountain, California (lat 35??N, long 240??E), contains three components of remanent magnetization. The first component (A; removed by ???100-???200 ??C) has a direction near the present-day field for southern California and is probably a recently acquired thermoviscous magnetization. A second component (B; removed between ???100 and ???600 ??C) is identical to that observed by previous workers in samples of underlying pillow basalt and overlying terrigenous sedimentary rocks. This component has constant normal polarity and direction throughout the entire section, although these rocks were deposited during a mixed polarity interval of the geomagnetic field. The B magnetization, therefore, is inferred to be a secondary magnetization acquired during accretion, uplift, or Miocene volcanism prior to regional clockwise rotation. The highest temperature component (C; removed between ???480 and 680 ??C) is of dual polarity and is tentatively interpreted as a primary magnetization, although it fails a reversal test possibly due to contamination by B. Separation of the B and C components is best shown by samples with negative-inclination C directions, and a corrected mean direction using only these samples indicates an initial paleolatitude of 32??N ?? 8??. Paleobiogeographic models relating radiolarian faunal distribution patterns to paleolatitude have apparently been incorrectly calibrated using the overprint B component. Few other paleomagnetic data have been incorporated in these models, and faunal distribution patterns are poorly known and mostly unqualified. The available data, therefore, do not support formation of the Coast Range ophiolite at Stanley Mountain near the paleoequator or accretion at ???10??N paleolatitude, as has been previously suggested based on paleomagnetic data, but indicate deposition near expected paleolatitudes for North America (35??N ?? 4??) during Late Jurassic

  16. Expediting the chemistry of hematite nanocatalyst for catalytic aquathermolysis of heavy crude oil

    Science.gov (United States)

    Khalil, Munawar

    In upstream exploration and production of heavy and extra heavy oil, catalytic aquathermolysis is a process where steam (along with catalyst) is injected into the reservoir to improve oil production. The improvement of oil production has been associated with the reduction of heavy oil's viscosity due to the degradation of large hydrocarbon molecules (resin and asphaltene fractions) which mostly the result of desulphurization of organosulphur compounds. In this work, the potential of hematite (alpha-Fe2O3) nanoparticles, a nontoxic, inexpensive and the most stable phase of iron oxide, was investigated for aquathermolysis application. This dissertation encompasses the synthesis, surface modification, catalytic activity, and catalysis mechanism of hematite nanoparticles in aquathermolysis. In the first part of this study, a simple hydrothermal method was successfully developed to synthesize hematite nanoparticles with high purity and good crystallinity. Using this method, the size, crystal's growth rate, shape, and dispersity of the nanoparticles can be controlled by the amount of iron precursor, precipitation agent, temperature and reaction time. Furthermore, the surface chemistry of hematite nanoparticle was modified in order to improve particle dispersibility in hydrocarbon phase. Based on the result, oleic acid (OA) was successfully grafted on the surface of hematite nanoparticles by forming a monodentate interaction and changed the surface property of the nanoparticles from hydrophilic to hydrophobic. As the result, nanoparticles were able to be transferred from aqueous phase to non-polar phase, vice versa, depending on the amount of oleic acid used for modification. In the third part of this work, the catalytic activity and catalytic mechanism of hematite nanoparticles to catalyze desulphurization reaction were studied. It is found that hematite nanoparticles have a good catalytic activity to decompose a highly stable aromatic organosulphur compound, i

  17. Differential cellular responses in healthy mice and in mice with established airway inflammation when exposed to hematite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Gustafsson, Åsa, E-mail: asa.gustafsson@foi.se [Swedish Defence Research Agency, Division of CBRN Defence and Security, Umeå (Sweden); Dept of Public Health and Clinical Medicine, Umeå University (Sweden); Bergström, Ulrika [Swedish Defence Research Agency, Division of CBRN Defence and Security, Umeå (Sweden); Dept of Organismal Biology, Uppsala University, SE-751 Uppsala (Sweden); Ågren, Lina [Swedish Defence Research Agency, Division of CBRN Defence and Security, Umeå (Sweden); Österlund, Lars [Dept of Engineering Sciences, The Ångström Laboratory, Uppsala University, SE-751 Uppsala (Sweden); Sandström, Thomas [Dept of Public Health and Clinical Medicine, Umeå University (Sweden); Bucht, Anders [Swedish Defence Research Agency, Division of CBRN Defence and Security, Umeå (Sweden); Dept of Public Health and Clinical Medicine, Umeå University (Sweden)

    2015-10-01

    The aim of this study was to investigate the inflammatory and immunological responses in airways and lung-draining lymph nodes (LDLNs), following lung exposure to iron oxide (hematite) nanoparticles (NPs). The responses to the hematite NPs were evaluated in both healthy non-sensitized mice, and in sensitized mice with an established allergic airway disease. The mice were exposed intratracheally to either hematite NPs or to vehicle (PBS) and the cellular responses were evaluated on days 1, 2, and 7, post-exposure. Exposure to hematite NPs increased the numbers of neutrophils, eosinophils, and lymphocytes in the airways of non-sensitized mice on days 1 and 2 post-exposure; at these time points the number of lymphocytes was also elevated in the LDLNs. In contrast, exposing sensitized mice to hematite NPs induced a rapid and unspecific cellular reduction in the alveolar space on day 1 post-exposure; a similar decrease of lymphocytes was also observed in the LDLN. The results indicate that cells in the airways and in the LDLN of individuals with established airway inflammation undergo cell death when exposed to hematite NPs. A possible explanation for this toxic response is the extensive generation of reactive oxygen species (ROS) in the pro-oxidative environment of inflamed airways. This study demonstrates how sensitized and non-sensitized mice respond differently to hematite NP exposure, and it highlights the importance of including individuals with respiratory disorders when evaluating health effects of inhaled nanomaterials. - Highlights: • Hematite NPs induce differential responses in airways of healthy and allergic mice. • Hematite induced an airway inflammation in healthy mice. • Hematite induced cellular reduction in the alveolus and lymph nodes of allergic mice. • Cell death is possible due to extensive pro-oxidative environment in allergic mice. • It is important to include sensitive individuals when valuing health effects of NPs.

  18. Reconstruction of Holocene changes in alpine vegetation and climate in the Maligne Range, Jasper National Park, Alberta

    Science.gov (United States)

    Luckman, B. H.; Kearney, M. S.

    1986-09-01

    Pollen, macrofossil (logs and needles), and oxygen-isotope data from tree rings are presented for three alpine bog sites in the Maligne Range of the Canadian Rockies. Organic sedimentation at the Watchtower site began prior to ca. 9500 14C yr B.P. and by 8770 yr B.P. timberlines were at least 100 m above present levels. The two pollen records are dominated by Pinus and subsequent changes in timberlines are inferred from pollen-ratio data ( Abies/Pinus) and from macrofossils. The recovered records indicate two periods of high Hypsithermal timberlines ca. 8800-7500 and 7200-5200 yr B.P. separated by a short interval ca. 7300-7400 yr B.P. when timberline approached modern levels. After ca. 4500 yr B.P. timberlines have been similar to or lower than present, reaching minimum values in the last 500 yr. δ 18O determinations from the α-cellulose of samples of 5 or 10 annual rings cut from contemporary Picea englemannii at timberline show strong correlations with mean annual temperatures at Jasper. Isotopic determinations from Hypsithermal-age logs recovered from sites above present timberline indicate mean annual temperatures were at least 0.5°C warmer ca. 8060 and 8770 yr B.P. than at present at the Watchtower site. Data from logs at the Maligne Pass site suggest that temperatures were about 1.2° and 1.6°C warmer ca. 6000 and 5300 yr B.P. Estimates of temperature from the pollen-ratio data are more conservative and suggest maximum differences of ca. 1.0°C in July temperatures over the last 8000 yr.

  19. Comparative study of the shield of concrete blocks with hematite in relation to common concrete blocks

    International Nuclear Information System (INIS)

    Costa, Paulo R.; Buerger, Andre A.; Naccache, Veronica K.; Priszkulnik, Simao

    2012-01-01

    The present work shows results of an empirical evaluation of the transmission properties of two radioprotection materials: an ordinary concrete and an ordinary concrete mixed with hematite. It was used techniques of x-ray spectroscopy and measurements of the air-kerma transmitted through these two materials in order to compare the transmission properties for each one. (author)

  20. Synthesis and photo-electrochemical properties of spinel-ferrite-coated hematite for solar water splitting

    Science.gov (United States)

    Selvaraj, Seenivasan; Moon, Hee; Kim, Do-Heyoung

    2018-01-01

    Photo-electrochemical water splitting with hematite photo-anodes under solar irradiation has attracted considerable attention as regards the production of renewable hydrogen energy. However, many challenges remain unresolved, as the full contribution of the catalytic over-layers has not been fully realized. Herein, we incorporate uniform spinel nickel-ferrite over-layers in hematite photo-anodes to obtain an improved understanding of the associated intrinsic changes. We achieve a 1.5-mA/cm2 photo-current density at 1.23 VRHE (RHE: reversible hydrogen electrode) under one-sun illumination conditions, along with a negative shift of 200 mV in the onset potential, for NiFe2O4-coated Sn-doped hematite photo-anodes. Fundamental electrochemical analyses clearly show that the shift in the onset potential is predominantly due to the enhanced photo-voltage development inside the hematite, rather than being purely caused by the interfacial kinetics. These insights reveal a new direction for fundamental research on photo-anodes towards fabrication of more efficient photo-anode systems.

  1. The colloid hematite particle migration through the unsaturated porous bed at the presence of biosurfactants.

    Science.gov (United States)

    Pawlowska, Agnieszka; Sznajder, Izabela; Sadowski, Zygmunt

    2017-07-01

    Colloidal particles have an ability to sorb heavy metals, metalloids, and organic compounds (e.g. biosurfactants) present in soil and groundwater. The pH and ionic strength changes may promote release of such particles causing potential contaminant transport. Therefore, it is very important to know how a colloid particle-mineral particle and colloid-mineral-biosurfactant system behaves in the natural environment. They can have negative impact on the environment and human health. This study highlighted the influence of biosurfactants produced by Pseudomonas aeruginosa on the transport of colloidal hematite (α-Fe 2 O 3 ) through porous bed (materials collected from the Szklary and Zloty Stok solid waste heaps from Lower Silesia, Poland). Experiments were conducted using column set in two variants: colloid solution with porous bed and porous bed with adsorbed biosurfactants, in the ionic strengths of 5 × 10 -4 and 5 × 10 -3  M KCl. The zeta potential of mineral materials and colloidal hematite, before and after adsorption of biosurfactant, was determined. Obtained results showed that reduction in ionic strength facilitates colloidal hematite transport through the porous bed. The mobility of colloidal hematite was higher when the rhamnolipid adsorbed on the surface of mineral grain.

  2. Thermal modification of hematite-ilmenite intergrowths in the Ecstall pluton, British Columbia, Canada

    DEFF Research Database (Denmark)

    Brownlee, S.J.; Feinberg, J.M.; Harrison, R.J.

    2010-01-01

    In this study, we examine the effects of reheating on finely exsolved hematite-ilmenite intergrowths from the similar to 91 Ma Ecstall pluton using reflected light microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). As a result of the emplacement of the you......In this study, we examine the effects of reheating on finely exsolved hematite-ilmenite intergrowths from the similar to 91 Ma Ecstall pluton using reflected light microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). As a result of the emplacement...... of the younger adjacent similar to 52 Ma Quottoon pluton, samples closer to a thermal boundary have experienced greater degrees of thermal alteration. Five main microstructural features characterize hematite-ilmenite intergrowths from the Ecstall: (I) exsolution lamellae of hematite and ilmenite; (II) oxidation....... Higher temperatures also enhanced oxidation in ilmenite. The formation of magnetite altered the bulk magnetic properties of these samples, increasing NRM intensity. This study underscores the need to consider a pluton's post-emplacement thermal history before making tectonic interpretations based...

  3. Characterization of U(VI)-carbonato ternary complexes on hematite: EXAFS and electrophoretic mobility measurements

    Science.gov (United States)

    Bargar, John R.; Reitmeyer, Rebecca; Lenhart, John J.; Davis, James A.

    2000-01-01

    We have measured U(VI) adsorption on hematite using EXAFS spectroscopy and electrophoresis under conditions relevant to surface waters and aquifers (0.01 to 10 μM dissolved uranium concentrations, in equilibrium with air, pH 4.5 to 8.5). Both techniques suggest the existence of anionic U(VI)-carbonato ternary complexes. Fits to EXAFS spectra indicate that U(VI) is simultaneously coordinated to surface FeO6 octahedra and carbonate (or bicarbonate) ligands in bidentate fashions, leading to the conclusion that the ternary complexes have an inner-sphere metal bridging (hematite-U(VI)-carbonato) structure. Greater than or equal to 50% of adsorbed U(VI) was comprised of monomeric hematite-U(VI)-carbonato ternary complexes, even at pH 4.5. Multimeric U(VI) species were observed at pH ≥ 6.5 and aqueous U(VI) concentrations approximately an order of magnitude more dilute than the solubility of crystalline β-UO2(OH)2. Based on structural constraints, these complexes were interpreted as dimeric hematite-U(VI)-carbonato ternary complexes. These results suggest that Fe-oxide-U(VI)-carbonato complexes are likely to be important transport-limiting species in oxic aquifers throughout a wide range of pH values.

  4. Ion adsorption on oxides : surface charge formation and cadmium binding on rutile and hematite

    NARCIS (Netherlands)

    Fokkink, L.G.J.

    1987-01-01

    The adsorption of charge-determining (H +and OH -) and cadmium ions on rutile (TiO 2 ) and hematite (α-Fe

  5. The Distribution of Crystalline Hematite on Mars from the Thermal Emission Spectrometer: Evidence for Liquid Water

    Science.gov (United States)

    Christensen, P. R.; Malin, M.; Morris, D.; Bandfield, J.; Lane, M.; Edgett, K.

    2000-01-01

    Crystalline hematite on Mars has been mapped using the MGS TES. Two major, and several minor areas of significant accumulation are identified. We favor precipitation models involving Fe-rich water, providing direct mineralogic evidence for large-scale water interactions.

  6. Resolving Iron(II) Sorption and Oxidative Growth on Hematite (001) Using Atom Probe Tomography

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, Sandra D. [Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, United States; Liu, Jia [Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, United States; Arey, Bruce W. [Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, United States; Schreiber, Daniel K. [Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, United States; Perea, Daniel E. [Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, United States; Rosso, Kevin M. [Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, United States

    2018-02-13

    The distribution of iron resulting from the autocatalytic interaction of aqueous Fe(II) with the hematite (001) surface was directly mapped in three dimensions (3D) for the first time, using iron isotopic labelling and atom probe tomography (APT). Analyses of the mass spectrum showed that natural abundance ratios in 56Fe-dominant hematite are recovered at depth with good accuracy, whereas at the relict interface with 57Fe(II) solution evidence for hematite growth by oxidative adsorption of Fe(II) was found. 3D reconstructions of the isotope positions along the surface normal direction showed a zone enriched in 57Fe, which was consistent with an average net adsorption of 3.2 – 4.3 57Fe atoms nm–2. Statistical analyses utilizing grid-based frequency distribution analyses show a heterogeneous, non-random distribution of oxidized Fe on the (001) surface, consistent with Volmer-Weber-like island growth. The unique 3D nature of the APT data provides an unprecedented means to quantify the atomic-scale distribution of sorbed 57Fe atoms and the extent of segregation on the hematite surface. This new ability to spatially map growth on single crystal faces at the atomic scale will enable resolution to long-standing unanswered questions about the underlying mechanisms for electron and atom exchange involved in a wide variety of redox-catalyzed processes at this archetypal and broadly relevant interface.

  7. Transformation of goethite/ferrihydrite to hematite and maghemite under temperate humid conditions in Denmark

    Science.gov (United States)

    Nørnberg, P.; Finster, K.; Gunnlaugsson, H. P.; Jensen, S. K.; Merrison, J. P.; Vendelboe, A. L.

    2012-04-01

    At a number of sandy soil sites in Mid Jutland, Denmark, with iron content of 1-2%, very red spots (Munsell colour: dusky red 10R 3/4) of a few square meters are found. These spots are most likely due to burning events. After the fire ashes raised pH. This dispersed silt and clay size soil particles which were then transported with seepage water down into lower soil horizons. These particles contain hematite and maghemite due to influence of the fire. However, a long-standing unresolved question is how hematite and maghemite can also be present along with goethite and ferrihydrite, in the same geographical region, and in extended areas with high iron content (8-40 %) in the topsoil. Hematite and particularly maghemite would normally not be expected to form under the temperate humid Danish climate, but be interpreted as the result of high temperature as found in tropical regions or as seen in soils exposed to fire. The high iron content most likely has its origin in pyrite dissolution in top of the groundwater zone in deeper Miocene deposits. From there Fe2+ is brought to the surface by the groundwater, and in wells oxidized by meeting the atmosphere and precipitated as two line ferrihydrite. This is later transformed into goethite. However, along with these two minerals hematite and maghemite are present in the topsoil around the well area. Forest fires would be a likely explanation to the hematite and maghemite. But a body of evidence argues against these sites having been exposed to fire. 1) The pH in the topsoil is 3.6 - 4.8 and thus not raised by ashes. 2) No charcoal is present. 3) There is no indication of fire outside the high iron content areas. 4) Goethite is present along with hematite and maghemite in microparticles, and the mineralogical zonation produced in a forest fire is not seen. The natural sites contain a uniform mixture of goethite/ferrihydrite, hematite and maghemite down to 20 cm depth. An experimental forest fire left charcoal and ashes at

  8. A late Frasnian (Late Devonian) radiolarian, sponge spicule, and conodont fauna from the Slaven Chert, northern Shoshone Range, Roberts Mountains allochthon, Nevada

    Science.gov (United States)

    Boundy-Sanders, S. Q.; Sandberg, C.A.; Murchey, B.L.; Harris, A.G.

    1999-01-01

    Co-occuring conodonts, radiolarians, and sponge spicules from the type locality of the Slaven Chert, northern Shoshone Range, Nevada, indicate that the radiolarian and sponge spicule assemblage described herein correlates with the Late rhenana conodont Zone (late Frasnian). The moderately well preserved radiolarians are the first Frasnian-age fauna described from the Western Hemisphere. They include spumellarians, Ceratoikiscum, and Paleoscenidium, and a radiolarian which we have assigned to a new genus, Durahelenifore Boundy-Sanders and Murchey, with its type species, Durahelenifore robustum Boundy-Sanders and Murchey. Sponge spicules include umbellate microscleres of the Subclass Amphidiscophora, Order Hemidiscosa, previously documented only in Pennsylvanian and younger rocks.

  9. Photoelectrochemical water splitting with mesoporous hematite prepared by a solution-based colloidal approach.

    Science.gov (United States)

    Sivula, Kevin; Zboril, Radek; Le Formal, Florian; Robert, Rosa; Weidenkaff, Anke; Tucek, Jiri; Frydrych, Jiri; Grätzel, Michael

    2010-06-02

    Sustainable hydrogen production through photoelectrochemical water splitting using hematite (alpha-Fe(2)O(3)) is a promising approach for the chemical storage of solar energy, but is complicated by the material's nonoptimal optoelectronic properties. Nanostructuring approaches have been shown to increase the performance of hematite, but the ideal nanostructure giving high efficiencies for all absorbed light wavelengths remains elusive. Here, we report for the first time mesoporous hematite photoelectodes prepared by a solution-based colloidal method which yield water-splitting photocurrents of 0.56 mA cm(-2) under standard conditions (AM 1.5G 100 mW cm(-2), 1.23 V vs reversible hydrogen electrode, RHE) and over 1.0 mA cm(-2) before the dark current onset (1.55 V vs RHE). The sintering temperature is found to increase the average particle size, and have a drastic effect on the photoactivity. X-ray photoelectron spectroscopy and magnetic measurements using a SQUID magnetometer link this effect to the diffusion and incorporation of dopant atoms from the transparent conducting substrate. In addition, examining the optical properties of the films reveals a considerable change in the absorption coefficient and onset properties, critical aspects for hematite as a solar energy converter, as a function of the sintering temperature. A detailed investigation into hematite's crystal structure using powder X-ray diffraction with Rietveld refinement to account for these effects correlates an increase in a C(3v)-type crystal lattice distortion to the improved optical properties.

  10. A Ga2O3 underlayer as an isomorphic template for ultrathin hematite films toward efficient photoelectrochemical water splitting.

    Science.gov (United States)

    Hisatomi, Takashi; Brillet, Jérémie; Cornuz, Maurin; Le Formal, Florian; Tétreault, Nicolas; Sivula, Kevin; Grätzel, Michael

    2012-01-01

    Hematite photoanodes for photoelectrochemical (PEC) water splitting are often fabricated as extremely-thin films to minimize charge recombination because of the short diffusion lengths of photoexcited carriers. However, poor crystallinity caused by structural interaction with a substrate negates the potential of ultrathin hematite photoanodes. This study demonstrates that ultrathin Ga2O3 underlayers, which were deposited on conducting substrates prior to hematite layers by atomic layer deposition, served as an isomorphic (corundum-type) structural template for ultrathin hematite and improved the photocurrent onset of PEC water splitting by 0.2 V. The benefit from Ga2O3 underlayers was most pronounced when the thickness of the underlayer was approximately 2 nm. Thinner underlayers did not work effectively as a template presumably because of insufficient crystallinity of the underlayer, while thicker ones diminished the PEC performance of hematite because the underlayer prevented electron injection from hematite to a conductive substrate due to the large conduction band offset. The enhancement of PEC performance by a Ga2O3 underlayer was more significant for thinner hematite layers owing to greater margins for improving the crystallinity of ultrathin hematite. It was confirmed that a Ga2O3 underlayer was applicable to a rough conducting substrate loaded with Sb-doped SnO2 nanoparticles, improving the photocurrent by a factor of 1.4. Accordingly, a Ga2O3 underlayer could push forward the development of host-guest-type nanocomposites consisting of highly-rough substrates and extremely-thin hematite absorbers.

  11. Fluoride ions sorption of the water using natural and modified hematite with aluminium hydroxide

    International Nuclear Information System (INIS)

    Teutli S, E. A.

    2011-01-01

    Fluorine is a mineral known for its dental benefits, but fluoride ions can cause fluoro sis in excessive quantities. There are many epidemiological studies on possible adverse effects resulting from prolonged ingestion of fluoride through drinking water. These studies demonstrate that fluoride mainly affects the bone tissue (bones and teeth), may produce an adverse effect on tooth enamel and can cause mild dental fluoro sis at concentrations from 0.9 to 1.2 mg/L in drinking water. In several states of Mexico, water contaminated with fluoride ions can be found, such as Aguascalientes, Chihuahua, Coahuila, Durango, Guanajuato, Sonora, Zacatecas, San Luis Potosi and Jalisco, where the fluoride ions levels are higher than 1.5 mg/L, established by the Mexican Official Standard (NOM-127-Ssa-2000) which sets the permissible limits of water for human use and consumption. Currently, several technologies have been proposed to remove fluoride ions from water such as precipitation methods which are based on the addition of chemicals to water and sorption methods to removed fluoride ions by sorption or ion exchange reactions by some suitable substrate capable of regenerate and reuse. In this work, the sorption of fluoride ions using unmodified and modified hematite with aluminum hydroxide to remove fluoride ions from water by bath experiments was studied. The hematite was modified by treating it with aluminum hydroxide, NaOH and Al 2 (SO 4 ) 3 solutions. The characterization of hematite before and after modification with aluminum hydroxide was studied by X-ray diffraction, scanning electron microscopy, EDS and Bet. The effect of ph, contact time, concentration of fluoride ions, and the dose of sorbent on the sorption of fluoride ions by the modified hematite were studied. Equilibrium was reached within 48 hours of contact time and the maximum sorption of fluoride ions were in the range pH eq between 2.3 and 6.2. Sorption capacities of fluoride ions as a function of dose of

  12. Adsorption of water and carbon dioxide on hematite and consequences for possible hydrate formation.

    Science.gov (United States)

    Kvamme, Bjørn; Kuznetsova, Tatiana; Kivelae, Pilvi-Helina

    2012-04-07

    The interest in carbon dioxide for enhanced oil recovery is increasing proportional to the decline in naturally driven oil production and also due to the increasing demand for reduced emission of carbon dioxide into the atmosphere. Transport of carbon dioxide in offshore pipelines involves high pressure and low temperatures, conditions which may lead to formation of hydrates from residual water dissolved in carbon dioxide and carbon dioxide. The critical question is whether the water at certain temperatures and pressures will drop out as liquid droplets first, and then form hydrates, or alternatively, adsorb on the pipeline surfaces, and subsequently form hydrates heterogeneously. In this work, we used several different basis sets of density functional theory in ab initio calculations to estimate the charge distribution of hematite (the dominating component of rust) crystals. These rust particles were embedded in water and chemical potential for adsorbed water molecules was estimated through thermodynamic integration and compared to similar estimates for water clusters of the same size. While the generated charges were not unique, the use of high order approximations and different basis sets provides a range of likely charge distributions. Values obtained for the chemical potential of water in different surroundings indicated that it would be thermodynamically favorable for water to adsorb on hematite, and that evaluation of potential carbon dioxide hydrate formation conditions and kinetics should be based on this formation mechanism. Depending on the basis set and approximations, the estimated gain for water to adsorb on the hematite surface rather than condense as droplets varied between -1.7 kJ mole(-1) and -3.4 kJ mole(-1). The partial charge distribution on the hematite surface is incompatible with the hydrate structure, and thus hydrates will be unable to attach to the surface. The behavior of water outside the immediate vicinity of hematite (beyond 3

  13. Iron Isotopes in Spherical Hematite and Goethite Concretions from the Navajo Sandstone (Utah, USA): A Prospective Study for "Martian Blueberries"

    Science.gov (United States)

    Busigny, V.; Dauphas, N.

    2006-03-01

    Iron isotopes of terrestrial hematite and goethite concretions provide clues on fluid transport, reservoir sizes, redox variations and biotic versus abiotic processes. This opens several avenues of research for future work on Martian blueberries.

  14. Faradaic efficiency of O2 evolution on metal nanoparticle sensitized hematite photoanodes

    DEFF Research Database (Denmark)

    Iandolo, Beniamino; Wickman, Björn; Seger, Brian

    2014-01-01

    in several studies, to the best of our knowledge no measurements of the Faradaic efficiency (FE) of the oxygen evolution reaction (OER) have been reported for such systems. This work characterizes the FE on a model system consisting of ultra-thin films of hematite (Fe2O3) sensitized with Ti/Au nanodisks....... Compared to bare hematite references, sensitized samples showed significantly enhanced photocurrents as well as O-2 evolution. Experimental evidence suggests that the observed enhancement was not due to photocatalytic activity of the nanodisks. The FE has been determined to be 100%, within the experimental...... errors, for both sensitized and reference samples. Also, this work demonstrates that the sensitized samples were stable for at least 16 hours photocurrent testing. The concepts shown in this work are generally applicable to any situation in which a semiconductor has its water splitting performance...

  15. Strontium-Doped Hematite as a Possible Humidity Sensing Material for Soil Water Content Determination

    Directory of Open Access Journals (Sweden)

    Carlo Grignani

    2013-09-01

    Full Text Available The aim of this work is to study the sensing behavior of Sr-doped hematite for soil water content measurement. The material was prepared by solid state reaction from commercial hematite and strontium carbonate heat treated at 900 °C. X-Ray diffraction, scanning electron microscopy and mercury intrusion porosimetry were used for microstructural characterization of the synthesized powder. Sensors were then prepared by uniaxially pressing and by screen-printing, on an alumina substrate, the prepared powder and subsequent firing in the 800–1,000 °C range. These sensors were first tested in a laboratory apparatus under humid air and then in an homogenized soil and finally in field. The results evidenced that the screen printed film was able to give a response for a soil matric potential from about 570 kPa, that is to say well below the wilting point in the used soil.

  16. Strontium-doped hematite as a possible humidity sensing material for soil water content determination.

    Science.gov (United States)

    Tulliani, Jean-Marc; Baroni, Chiara; Zavattaro, Laura; Grignani, Carlo

    2013-09-10

    The aim of this work is to study the sensing behavior of Sr-doped hematite for soil water content measurement. The material was prepared by solid state reaction from commercial hematite and strontium carbonate heat treated at 900 °C. X-Ray diffraction, scanning electron microscopy and mercury intrusion porosimetry were used for microstructural characterization of the synthesized powder. Sensors were then prepared by uniaxially pressing and by screen-printing, on an alumina substrate, the prepared powder and subsequent firing in the 800-1,000 °C range. These sensors were first tested in a laboratory apparatus under humid air and then in an homogenized soil and finally in field. The results evidenced that the screen printed film was able to give a response for a soil matric potential from about 570 kPa, that is to say well below the wilting point in the used soil.

  17. Surface Interrogation Scanning Electrochemical Microscopy for a Photoelectrochemical Reaction: Water Oxidation on a Hematite Surface.

    Science.gov (United States)

    Kim, Jae Young; Ahn, Hyun S; Bard, Allen J

    2018-03-06

    To understand the pathway of a photoelectrochemical (PEC) reaction, quantitative knowledge of reaction intermediates is important. We describe here surface interrogation scanning electrochemical microscopy for this purpose (PEC SI-SECM), where a light pulse to a photoactive semiconductor film at a given potential generates intermediates that are then analyzed by a tip generated titrant at known times after the light pulse. The improvements were demonstrated for photoelectrochemical water oxidation (oxygen evolution) reaction on a hematite surface. The density of photoactive sites, proposed to be Fe 4+ species, on a hematite surface was successfully quantified, and the photoelectrochemical water oxidation reaction dynamics were elucidated by time-dependent redox titration experiments. The new configuration of PEC SI-SECM should find expanded usage to understand and investigate more complicated PEC reactions with other materials.

  18. Transformation of Goethite to Hematite Nanocrystallines by High Energy Ball Milling

    Directory of Open Access Journals (Sweden)

    O. M. Lemine

    2014-01-01

    Full Text Available α-Fe2O3 nanocrystallines were prepared by direct transformation via high energy ball milling treatment for α-FeOOH powder. X-ray diffraction, Rietveld analysis, TEM, and vibrating sample magnetometer (VSM are used to characterize the samples obtained after several milling times. Phase identification using Rietveld analysis showed that the goethite is transformed to hematite nanocrystalline after 40 hours of milling. HRTEM confirm that the obtained phase is mostly a single-crystal structure. This result suggested that the mechanochemical reaction is an efficient way to prepare some iron oxides nanocrystallines from raw materials which are abundant in the nature. The mechanism of the formation of hematite is discussed in text.

  19. Surfactant-assisted solvothermal preparation of submicrometer-sized hollow hematite particles and their photocatalytic activity

    International Nuclear Information System (INIS)

    Lian Suoyuan; Wang Enbo; Gao Lei; Wu Di; Song Yanli; Xu Lin

    2006-01-01

    Submicrometer-sized hollow hematite particles were prepared through a surfactant-assisted solvothermal process. The amount of FeCl 3 .H 2 O and cetyltrimethylammonium bromide, and the acidity of the solution were systematically altered to study their effects on the final results. Hollow hematite particles with shapes from sphere, ellipsoid to peanut were obtained. Their sizes range from 500 nm to 2 μm with shell thickness from 100 to 500 nm. Powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy and selected area electron diffraction were applied to investigate the products' crystallinity, purity, morphology, size and structural features. Finally, the study on the photocatalysis of Fe 2 O 3 for the destruction of diethyl phthalate in water was carried out. The result proved that Fe 2 O 3 hollow particles were effective photocatalysts for the degradation of DEP, with 96.8% destruction ratio being obtained within 60 min

  20. High-power pulsed plasma deposition of hematite photoanode for PEC water splitting

    Czech Academy of Sciences Publication Activity Database

    Kment, Š.; Hubička, Zdeněk; Krysa, J.; Olejníček, Jiří; Čada, Martin; Gregora, Ivan; Zlámal, M.; Brunclíková, Michaela; Remeš, Zdeněk; Liu, N.; Wang, L.; Kirchgeorg, R.; Lee, Ch.Y.; Schmuki, P.

    2014-01-01

    Roč. 230, Jul (2014), 8-14 ISSN 0920-5861 R&D Projects: GA ČR GAP108/12/2104; GA MŠk LH12043 Institutional support: RVO:68378271 Keywords : electrical properties * hematite * HiPIMS * hollow cathode plasma jet * photoelectrochemical water splitting * thin films Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 3.893, year: 2014

  1. Stereo soft x-ray microscopy and elemental mapping of hematite and clay suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Gleber, S.-C.; Thieme, J.; Chao, W.; Fischer, P.

    2008-09-01

    The spatial arrangements of hematite particles within aqueous soil and clay samples are investigated with soft X-ray microscopy, taking advantage of the elemental contrast at the Fe-L edge around E = 707 eV. In combination with stereo microscopy, information about spatial arrangements are revealed and correlated to electrostatic interactions of the different mixtures. Manipulation of a sample mounted to the microscope is possible and particles added while imaging can be detected.

  2. Effect of Mica and Hematite (001) Surfaces on the Precipitation of Calcite

    OpenAIRE

    Huifang Xu; Mo Zhou; Yihang Fang; H. Henry Teng

    2018-01-01

    The substrate effect of mica and hematite on the nucleation and crystallization of calcite was investigated using scanning electron microscope (SEM), X-ray diffraction (XRD), and electron backscatter diffraction (EBSD) methods. On mica, we found, in the absence of Mg2+, the substrates’ (001) surfaces with hexagonal and pseudo-hexagonal two-dimensional (2-D) structure can affect the orientation of calcite nucleation with calcite (001) ~// mica (001) and calcite (010) ~// mica (010) to be the m...

  3. Hematite/silver nanoparticle bilayers on mica--AFM, SEM and streaming potential studies.

    Science.gov (United States)

    Morga, Maria; Adamczyk, Zbigniew; Oćwieja, Magdalena; Bielańska, Elżbieta

    2014-06-15

    Bilayers of hematite/silver nanoparticles were obtained in the self-assembly process and thoroughly characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), and in situ streaming potential measurements. The hematite nanoparticles, forming a supporting layer, were 22 nm in diameter, exhibiting an isoelectric point at pH 8.9. The silver nanoparticles, used to obtain an external layer, were 29 nm in diameter, and remained negative within the pH range 3 to 11. In order to investigate the particle deposition, mica sheets were used as a model solid substrate. The coverage of the supporting layer was adjusted by changing the bulk concentration of the hematite suspension and the deposition time. Afterward, silver nanoparticle monolayers of controlled coverage were deposited under the diffusion-controlled transport. The coverage of bilayers was determined by a direct enumeration of deposited particles from SEM micrographs and AFM images. Additionally, the formation of the hematite/silver bilayers was investigated by streaming potential measurements carried out under in situ conditions. The effect of the mica substrate and the coverage of a supporting layer on the zeta potential of bilayers was systematically studied. It was established that for the coverage exceeding 0.20, the zeta potential of bilayers was independent on the substrate and the supporting layer coverage. This behavior was theoretically interpreted in terms of the 3D electrokinetic model. Beside significance for basic sciences, these measurements allowed to develop a robust method of preparing nanoparticle bilayers of controlled properties, having potential applications in catalytic processes. Copyright © 2014 Elsevier Inc. All rights reserved.

  4. Adhesion of Escherichia coli onto quartz, hematite and corundum: extended DLVO theory and flotation behavior.

    Science.gov (United States)

    Farahat, Mohsen; Hirajima, Tsuyoshi; Sasaki, Keiko; Doi, Katsumi

    2009-11-01

    The adhesion of Escherichia coli onto quartz, hematite and corundum was experimentally investigated. A strain of E. coli was used that had the genes for expressing protein for silica precipitation. The maximum cell adhesion was observed at pH mineral adhesion was assessed by the extended DLVO theory approach. The essential parameters for calculation of microbe-mineral interaction energy (Hamaker constants and acid-base components) were experimentally determined. The extended DLVO approach could be used to explain the results of the adhesion experiments. The effect of E. coli on the floatability of three oxide minerals was determined and the results showed that E. coli can act as a selective collector for quartz at acidic pH values, with 90% of the quartz floated at 1.5 x 10(9)cells/ml. However, only 9% hematite and 30% corundum could be floated under similar conditions. By using E. coli and no reagents, it was possible to separate quartz from a hematite-quartz mixture with Newton's efficiency of 0.70. Removal of quartz from the corundum mixture was achieved by E. coli with Newton's efficiency of 0.62.

  5. Synthesis and characterization of hematite pigment obtained from a steel waste industry

    Energy Technology Data Exchange (ETDEWEB)

    Prim, S.R. [Department of Mechanical Engineering, University of the State of Santa Catarina, Santa Catarina (Brazil); Folgueras, M.V., E-mail: dem2mvf@joinville.udesc.br [Department of Mechanical Engineering, University of the State of Santa Catarina, Santa Catarina (Brazil); Lima, M.A. de [Department of Mechanical Engineering, University of the State of Santa Catarina, Santa Catarina (Brazil); Hotza, D. [Departamento de Engenharia Quimica, Federal University of Santa Catarina, Santa Catarina (Brazil)

    2011-09-15

    Highlights: {yields} The study of using of a industrial waste for the synthesis of hematite pigments. {yields} The nanometer dimension this waste and your behavior as chromophore. {yields} The effect of process variables on the mechanisms of encapsulation sintered pigments. - Abstract: Pigments that meet environmental and technology requirements are the focus of the research in the ceramic sector. This study focuses on the synthesis of ceramic pigment by encapsulation of hematite in crystalline and amorphous silica matrix. Iron oxide from a metal sheet rolling process was used as chromophore. A different content of hematite and silica was homogenized by conventional and high energy milling. The powders obtained after calcinations between 1050 and 1200 {sup o}C for 2 h were characterized by X-ray diffraction and SEM analysis. The pigments were applied to ceramic enamel and porcelain body. The effect of pigment was measured by comparing L*a*b* values of the heated samples. Results showed that the color developed is influenced by variables such as oxide content employed, conditions of milling and processing temperature. The results showed that the use of pigment developed does not interfere in microstructural characteristics of pigmented material. The best hue was obtained from samples with 15 wt% of chromophore, heated at 1200 {sup o}C in amorphous silica matrix.

  6. ADSORPTION OF PARAQUAT DICHLORIDE TO KAOLIN PARTICLES AND TO MIXTURES OF KAOLIN AND HEMATITE PARTICLES

    Directory of Open Access Journals (Sweden)

    Dina Alexandra Martins

    2015-03-01

    Full Text Available Deliberate contamination with pesticides is a potential risk to water security, due to the availability of these contaminants and the fact that they do not need special expertise to handle or apply. Adsorption of the herbicide paraquat from an aqueous solution to suspended particles of kaolin and kaolin/hematite mixture was investigated by kinetic and equilibrium assays, taking into consideration several parameters such as initial pH, sorbent dosage and agitation speed. The results showed that the adsorption process is quite fast, reaching an 18% reduction in paraquat concentration in a very short period of time. The addition of hematite particles to kaolin suspension had no apparent effect on the maximum amount of paraquat adsorbed. Kinetic parameters were determined by fitting the pseudo-second order model to the experimental data (correlation coefficients close to 1. Isotherm studies indicate an inhibitory effect, promoted by hematite particles, that was not detected in the adsorption assays. Equilibrium data was best adjusted using the Langmuir model which yielded higher correlation coefficient values and smaller normalized standard deviations.

  7. Impact of water quality parameters on the sorption of U(VI) onto hematite

    International Nuclear Information System (INIS)

    Zhao Donglin; Wang Xianbiao; Yang Shitong; Guo Zhiqiang; Sheng Guodong

    2012-01-01

    In this study, the sorption of U(VI) from aqueous solution on hematite was studied as a function of various water quality parameters such as contact time, pH, ionic strength, soil humic acid (HA) or fulvic acid (FA), solid content and temperature by using a batch technique. The results demonstrated that the sorption of U(VI) was strongly dependent on ionic strength at pH 6.0 and the sorption was mainly dominated by inner-sphere surface complexation. The presence of HA/FA increases U(VI) sorption at low pH, whereas decreases U(VI) sorption at high pH. The thermodynamic parameters (ΔH 0 , ΔS 0 , and ΔG 0 ) were calculated from the temperature dependent sorption isotherms, and the results suggested that U(VI) sorption was a spontaneous and endothermic process. The results might be important for the application of hematite in U(VI) pollution management. Highlights: ► The sorption of U(VI) was strongly dependent on ionic strength at pH 6.0. ► A positive effect of HA/FA on U(VI) sorption was found at low pH, whereas a negative effect was observed at high pH. ► U(VI) sorption was a spontaneous and endothermic process. ► The results are quite important for the application of hematite in U(VI) pollution management.

  8. Effect of Mica and Hematite (001 Surfaces on the Precipitation of Calcite

    Directory of Open Access Journals (Sweden)

    Huifang Xu

    2018-01-01

    Full Text Available The substrate effect of mica and hematite on the nucleation and crystallization of calcite was investigated using scanning electron microscope (SEM, X-ray diffraction (XRD, and electron backscatter diffraction (EBSD methods. On mica, we found, in the absence of Mg2+, the substrates’ (001 surfaces with hexagonal and pseudo-hexagonal two-dimensional (2-D structure can affect the orientation of calcite nucleation with calcite (001 ~// mica (001 and calcite (010 ~// mica (010 to be the major interfacial relationship. On hematite, we did not observe frequent twinning relationship between adjacent calcite gains, but often saw preferentially nucleation of calcite at surface steps on hematite substrate. We suggest that calcite crystals initially nucleate from the Ca2+ layers adsorbed on the surfaces. The pseudo-hexagonal symmetry on mica (001 surface also leads to the observed calcite (001 twinning. A second and less common orientation between calcite {104} and mica (001 was detected but could be due to local structure damage of the mica surface. Results in the presence of Mg2+ show that the substrate surfaces can weaken Mg toxicity to calcite nucleation and lead to a higher level of Mg incorporation into calcite lattice.

  9. Experimental evidence for non-redox transformations between magnetite and hematite under H 2-rich hydrothermal conditions

    Science.gov (United States)

    Otake, Tsubasa; Wesolowski, David J.; Anovitz, Lawrence M.; Allard, Lawrence F.; Ohmoto, Hiroshi

    2007-05-01

    Transformations of magnetite (Fe IIFe 2IIIO 4) to hematite (Fe 2IIIO 3) (and vice versa) have been thought by many scientists and engineers to require molecular O 2 and/or H 2. Thus, the presence of magnetite and/or hematite in rocks has been linked to a specific oxidation environment. However, the availability of reductants or oxidants in many geologic and industrial environments appears to have been too low to account for the transformations of iron oxides through redox reactions. Here, we report the results of hydrothermal experiments in mildly acidic and H 2-rich aqueous solutions at 150 °C, which demonstrate that transformations of magnetite to hematite, and hematite to magnetite, occur rapidly without involving molecular O 2 or H 2: Fe3O 4(Mt) + 2H (aq)+ ↔ Fe 2O 3(Hm) + Fe (aq)2+ + H 2O. The transformation products are chemically and structurally homogeneous, and typically occur as euhedral single crystals much larger than the precursor minerals. This suggests that, in addition to the expected release of aqueous ferrous species to solution, the transformations involve release of aqueous ferric species from the precursor oxides to the solution, which reprecipitate without being reduced by H 2. These redox-independent transformations may have been responsible for the formation of some iron oxides in natural systems, such as high-grade hematite ores that developed from Banded Iron Formations (BIFs), hematite-rich deposits formed on Mars, corrosion products in power plants and other industrial systems.

  10. Gas storage in the Upper Devonian-Lower Mississippian Woodford Shale, Arbuckle Mountains, Oklahoma: how much of a role do the cherts play?

    Science.gov (United States)

    Fishman, Neil S.; Ellis, Geoffrey S.; Paxton, Stanley T.; Abbott, Marvin M.; Boehlke, Adam

    2010-01-01

    How gas is stored in shale-gas systems is a critical element in characterizing these potentially prolific, low-porosity/permeability reservoirs. An integrated mineralogic, geochemical, and porosity/permeability study is of the Upper Devonian-Lower Mississippian Woodford Shale, Arbuckle Mountains, southern Oklahoma, at locations previously described through detailed stratigraphic and spectral gamma surveys, was undertaken to provide insights into possible mechanisms by which natural gas might be stored in Woodford reservoirs in the adjacent Anadarko Basin. The outcrops in the Arbuckle Mountains are an ideal location to study the Woodford because here the formation is immature or marginally mature for oil generation (Comer and Hinch, 1987; Lewan, 1987), so deep burial and thermal maturation are much less pronounced than is the case for the Woodford in the basin, and as such the samples we studied are not overprinted by possible alterations resulting from deep burial and heating. Rock types studied in the Woodford Shale are broadly divided into chert (n = 8) and mudstone (n = 10) lithologies that display different characteristics from the outcrop to thin section scales. Woodford cherts, based on quantitative X-ray diffraction (XRD), contain >85 weight (wt) % quartz, green algae). Quartz in mudstones is both detrital and authigenic, with unequivocal authigenic quartz occurring as monocrystalline “grains” that can partly or even completely infill Tasmanites; as in the case of the cherts, authigenic quartz in mudstones must have precipitated soon after deposition before significant burial and collapse of the soft, delicate Tasmanites cysts. MICP analyses (at 50% Hg saturation) reveal that, with one exception, mudstones have (1) porosities ranging from 1.97-6.31%, (2) low calculated permeabilities (0.011-0.089 D), and (3) small mean pore apertures (6.2-17.8 nm). Porosity in the mudstones occurs as (1) “slots” between clay mineral grains or plates, (2) micropores

  11. Effects of annealing temperature on the physicochemical, optical and photoelectrochemical properties of nanostructured hematite thin films prepared via electrodeposition method

    International Nuclear Information System (INIS)

    Phuan, Yi Wen; Chong, Meng Nan; Zhu, Tao; Yong, Siek-Ting; Chan, Eng Seng

    2015-01-01

    Highlights: • Nanostructured hematite thin films were synthesized via electrodeposition method. • Effects of annealing on size, grain boundary and PEC properties were examined. • Photocurrents generation was enhanced when the thin films were annealed at 600 °C. • The highest photocurrent density of 1.6 mA/cm 2 at 0.6 V vs Ag/AgCl was achieved. - Abstract: Hematite (α-Fe 2 O 3 ) is a promising photoanode material for hydrogen production from photoelectrochemical (PEC) water splitting due to its wide abundance, narrow band-gap energy, efficient light absorption and high chemical stability under aqueous environment. The key challenge to the wider utilisation of nanostructured hematite-based photoanode in PEC water splitting, however, is limited by its low photo-assisted water oxidation caused by large overpotential in the nominal range of 0.5–0.6 V. The main aim of this study was to enhance the performance of hematite for photo-assisted water oxidation by optimising the annealing temperature used during the synthesis of nanostructured hematite thin films on fluorine-doped tin oxide (FTO)-based photoanodes prepared via the cathodic electrodeposition method. The resultant nanostructured hematite thin films were characterised using field emission-scanning electron microscopy (FE-SEM) coupled with energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), UV-visible spectroscopy and Fourier transform infrared spectroscopy (FTIR) for their elemental composition, average nanocrystallites size and morphology; phase and crystallinity; UV-absorptivity and band gap energy; and the functional groups, respectively. Results showed that the nanostructured hematite thin films possess good ordered nanocrystallites array and high crystallinity after annealing treatment at 400–600 °C. FE-SEM images illustrated an increase in the average hematite nanocrystallites size from 65 nm to 95 nm when the annealing temperature was varied from 400 °C to 600 °C. As the

  12. Effects of annealing temperature on the physicochemical, optical and photoelectrochemical properties of nanostructured hematite thin films prepared via electrodeposition method

    Energy Technology Data Exchange (ETDEWEB)

    Phuan, Yi Wen [School of Engineering, Chemical Engineering Discipline, Monash University Malaysia, Jalan Lagoon Selatan, Bandar Sunway 46150 Selangor DE (Malaysia); Chong, Meng Nan, E-mail: Chong.Meng.Nan@monash.edu [School of Engineering, Chemical Engineering Discipline, Monash University Malaysia, Jalan Lagoon Selatan, Bandar Sunway 46150 Selangor DE (Malaysia); Sustainable Water Alliance, Advanced Engineering Platform, Monash University Malaysia, Jalan Lagoon Selatan, Bandar Sunway 46150 Selangor DE (Malaysia); Zhu, Tao; Yong, Siek-Ting [School of Engineering, Chemical Engineering Discipline, Monash University Malaysia, Jalan Lagoon Selatan, Bandar Sunway 46150 Selangor DE (Malaysia); Chan, Eng Seng [School of Engineering, Chemical Engineering Discipline, Monash University Malaysia, Jalan Lagoon Selatan, Bandar Sunway 46150 Selangor DE (Malaysia); Sustainable Water Alliance, Advanced Engineering Platform, Monash University Malaysia, Jalan Lagoon Selatan, Bandar Sunway 46150 Selangor DE (Malaysia)

    2015-09-15

    Highlights: • Nanostructured hematite thin films were synthesized via electrodeposition method. • Effects of annealing on size, grain boundary and PEC properties were examined. • Photocurrents generation was enhanced when the thin films were annealed at 600 °C. • The highest photocurrent density of 1.6 mA/cm{sup 2} at 0.6 V vs Ag/AgCl was achieved. - Abstract: Hematite (α-Fe{sub 2}O{sub 3}) is a promising photoanode material for hydrogen production from photoelectrochemical (PEC) water splitting due to its wide abundance, narrow band-gap energy, efficient light absorption and high chemical stability under aqueous environment. The key challenge to the wider utilisation of nanostructured hematite-based photoanode in PEC water splitting, however, is limited by its low photo-assisted water oxidation caused by large overpotential in the nominal range of 0.5–0.6 V. The main aim of this study was to enhance the performance of hematite for photo-assisted water oxidation by optimising the annealing temperature used during the synthesis of nanostructured hematite thin films on fluorine-doped tin oxide (FTO)-based photoanodes prepared via the cathodic electrodeposition method. The resultant nanostructured hematite thin films were characterised using field emission-scanning electron microscopy (FE-SEM) coupled with energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), UV-visible spectroscopy and Fourier transform infrared spectroscopy (FTIR) for their elemental composition, average nanocrystallites size and morphology; phase and crystallinity; UV-absorptivity and band gap energy; and the functional groups, respectively. Results showed that the nanostructured hematite thin films possess good ordered nanocrystallites array and high crystallinity after annealing treatment at 400–600 °C. FE-SEM images illustrated an increase in the average hematite nanocrystallites size from 65 nm to 95 nm when the annealing temperature was varied from 400 °C to 600

  13. Formation of complexes between hematite nanoparticles and a non-conventional galactomannan gum. Toward a better understanding on interaction processes.

    Science.gov (United States)

    Busch, Verónica M; Loosli, Fréderic; Santagapita, Patricio R; Buera, M Pilar; Stoll, Serge

    2015-11-01

    The physicochemical characteristics of hematite nanoparticles related to their size, surface area and reactivity make them useful for many applications, as well as suitable models to study aggregation kinetics. For several applications (such as remediation of contaminated groundwater) it is crucial to maintain the stability of hematite nanoparticle suspensions in order to assure their arrival to the target place. The use of biopolymers has been proposed as a suitable environmentally friendly option to avoid nanoparticle aggregation and assure their stability. The aim of the present work was to investigate the formation of complexes between hematite nanoparticles and a non-conventional galactomannan (vinal gum--VG) obtained from Prosopis ruscifolia in order to promote hematite nanoparticle coating with a green biopolymer. Zeta potential and size of hematite nanoparticles, VG dispersions and the stability of their mixtures were investigated, as well as the influence of the biopolymer concentration and preparation method. DLS and nanoparticle tracking analysis techniques were used for determining the size and the zeta-potential of the suspensions. VG showed a polydispersed size distribution (300-475 nm Z-average diameter, 0.65 Pdi) and a negative zeta potential (between -1 and -12 mV for pH2 and 12, respectively). The aggregation of hematite nanoparticles (3.3 mg/L) was induced by the addition of VG at lower concentrations than 2mg/L (pH5.5). On the other hand, hematite nanoparticles were stabilized at concentrations of VG higher than 2 mg/L. Several phenomena between hematite nanoparticles and VG were involved: steric effects, electrostatic interactions, charge neutralization, charge inversion and polymer bridging. The process of complexation between hematite nanoparticles and the biopolymer was strongly influenced by the preparation protocols. It was concluded that the aggregation, dispersion, and stability of hematite nanoparticles depended on biopolymer

  14. The impact of solution chemistry of electrolyte on the sorption of pentachlorophenol and phenanthrene by natural hematite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Fanfeng; He, Yan, E-mail: yhe2006@zju.edu.cn; Lian, Zhenghua; Xu, Jianming, E-mail: jmxu@zju.edu.cn

    2014-01-01

    Hematite nanoparticles (NPs) were studied as a sorbent for hydrophobic organic contaminants (OCs) under natural ambient conditions through specially designed contrasting solution chemistry of electrolyte. Ionizable pentachlorophenol (PCP) and non-ionizable phenanthrene (PHE) were selected as representative OCs. The sorption capacities of PCP and PHE were pH-dependent, and a larger amount of PCP was sorbed at pH values below its pK{sub a} (4.75). However, the PHE sorption capacity was higher at relatively high or low pHs (e.g. below 4.0 and above 10.0), possibly due to the larger available surface area of the hematite NPs, caused by the higher values of net charges and charge density. Changes in pH might thus affect the sorption of OCs by hematite NPs, through modification of the surface characteristics of the sorbent and the electronic properties of the sorbate molecules. The influence of different ionic strengths indicated that the amounts of PCP and PHE sorbed by hematite NPs decreased as a concentration function of different types of ions (e.g. Na{sup +}, K{sup +}, Mg{sup 2 +} and Ca{sup 2 +}), with the underlying mechanism possibly being due to four interactions i.e. hydrogen-bonding, competitive sorption by ions in the ambient solution, screening effects and aggregation effects. The results confirmed that the surface chemistry of hematite NPs, the chemical properties of PCP and PHE, and solution chemistry (e.g. pH and ionic strength) of the electrolyte all played an important role in PCP and PHE sorption by hematite NPs. By comparison of both sorption capacity and ecologic advantages, our results suggested that natural hematite NPs would be more competitive and efficient for PCP and PHE sorption than engineered NPs. This finding increases our knowledge regarding the environmental function of natural NPs (such as hematite NPs) for OC remediation through manipulating their interfacial behavior. - Highlights: •Hematite NPs was tested for PCP/PHE sorption under

  15. Karl Jaspers: as bases da orientação científica para viver. Um diálogo com Kant

    OpenAIRE

    Carvalho, José Mauricio de

    2016-01-01

    Nesse trabalho examina-se, segundo Karl Jaspers, até onde a ciência pode servir como orientação para viver. O conhecimento científico não alcança o ser em si, já dizia Kant, tem limites para alcançar e prever o funcionamento do núcleo da matéria, ensina a Física contemporânea. Por outro lado, a razão também encontra limite na liberdade pessoal, o que faz as ciências humanas precisarem conviver com essa limitação. Assim, uma orientação para viver que necessita de uma imagem completa do mund...

  16. Pressure response of vacancy ordered maghemite (γ-Fe2O3) and high pressure transformed hematite (α-Fe2O3)

    Science.gov (United States)

    Hearne, Giovanni; Pischedda, Vittoria

    2012-03-01

    Combined XRD and Mössbauer effect spectroscopy studies to high pressures of ˜30 GPa of vacancy ordered maghemite are presented. The vacancy ordered superstructure is robust and remains intact up to the pressure-induced onset transition to hematite at 13-16 GPa. The pressure transformed hematite is shown to be crystallographically textured, unlike the randomised low pressure maghemite phase. This arises out of a pressure or stress instigated topotactic transformation of the cubic-spinel to hexagonal-corundum structure. The textured sample permits us to obtain information on the spin reorientation behavior of the pressure transformed hematite in compression and decompression sequences. Spin reorientation is restricted to ˜15° over wide pressure ranges, attributable to the effect of entrapped vacancies in the high pressure structure. Thus there are structural and magnetic peculiarities specific to pressure transformed hematite not evident in pressurized hematite starting material. These are triggered by the maghemite→hematite transformation.

  17. Ocre, hematites y óxido de hierro: el problema terminológico = Ochre, Hematite and Iron Oxid: The Terminological Issue

    Directory of Open Access Journals (Sweden)

    Alfredo Cortell Nicolau

    2016-12-01

    Full Text Available Los óxidos de hierro son prácticamente omnipresentes al analizar contextos, no solo referentes al arte rupestre, sino también en relación con toda una serie de actividades que podríamos considerar cotidianas en ambientes prehistóricos. Sin embargo, su estudio sistemático no ha comenzado hasta tiempos muy recientes. Fruto de ello, podría decirse que una parte de la literatura arqueológica no especializada en el campo de la pigmentología muestra, en ocasiones, cierta inexactitud terminológica. Con este documento pretendemos, a través de un análisis tanto de su funcionamiento, como de las propiedades geoquímicas y mineralógicas del ocre, la hematites y los propios óxidos de hierro, exponer la necesidad de propiedad en su nomenclatura, así como los problemas que podrían derivarse de la falta de precisión. Por último, establecemos algunas propuestas que tal vez pudieran ayudar en esta normativización. Iron oxides are virtually omnipresent when analyzing contexts, not only referring to rock art, but also related to a whole series of activities, which we could consider as quotidian for prehistoric environments. Nevertheless, a systematic study of these has not started until recent times. As a result, it could be argued that a part of archaeological literature, not specialized on pigmentology, shows sometimes a certain lack of terminological accurateness. With this document we mean to, through an analysis both of the functioning and the geochemical and mineralogical properties of ochre, hematite and iron oxides themselves, expose the need for an appropriate terminology, as well as to show the problems derived from an inadequate naming. Finally, we bring some proposals, which could maybe help on an appropriate terminological standardization.

  18. Fabrication of hematite (α-Fe{sub 2}O{sub 3}) nanoparticles using electrochemical deposition

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Qingling; Wang, Zuobin, E-mail: wangz@cust.edu.cn; Chai, Xiangyu; Weng, Zhankun; Ding, Ran; Dong, Litong

    2016-04-15

    Graphical abstract: - Highlights: • Cathodic electrochemical deposition proposed to fabricate hematite nanoparticles. • Hematite nanoparticles were fabricated on indium-tin-oxide coated glass substrates. • The size and shape of nanoparticles were determined by deposition conditions. • The nanoparticles were well decentralized for different potential applications. • Electrochemical deposition is a useful approach in fabricating nanoparticles. - Abstract: In this work, cathodic electrochemical deposition was proposed to fabricate reproducible and homogeneous hematite (α-Fe{sub 2}O{sub 3}) nanoparticles on indium-tin-oxide (ITO) films. The α-Fe{sub 2}O{sub 3} nanoparticles, which were quasi-hexagonally shaped, were deposited in an aqueous mixture of FeCl{sub 2} and FeCl{sub 3} at the temperatures 16.5 °C, 40 °C and 60 °C. The electrochemically deposited α-Fe{sub 2}O{sub 3} nanoparticles showed excellent stability and good crystallinity. The α-Fe{sub 2}O{sub 3} nanoparticles were characterized by Raman spectroscope and X-ray diffractometer (XRD). A scanning electron microscope (SEM) was used to measure the size and shape of the nanoparticles. The experiment results have shown that the size and shape of nanoparticles were determined by electrochemical deposition conditions including the deposition time, current density, reaction temperature and solution concentration. The proposed electrochemical deposition method has been proven to be a cost-effective, environment friendly and highly efficient approach in fabricating well decentralized α-Fe{sub 2}O{sub 3} nanoparticles for different potential applications.

  19. Spectroscopic evidence for ternary surface complexes in the lead(II)-malonic acid-hematite system

    Science.gov (United States)

    Lenhart, J.J.; Bargar, J.R.; Davis, J.A.

    2001-01-01

    Using extended X-ray absorption fine structure (EXAFS) and attenuated total reflectance Fourier-transform infrared (ATR-FTIR) measurements, we examined the sorption of Pb(II) to hematite in the presence of malonic acid. Pb LIII-edge EXAFS measurements performed in the presence of malonate indicate the presence of both Fe and C neighbors, suggesting that a major fraction of surface-bound malonate is bonded to adsorbed Pb(II). In the absence of Pb(II), ATR-FTIR measurements of sorbed malonate suggest the formation of more than one malonate surface complex. The dissimilarity of the IR spectrum of malonate sorbed on hematite to those for aqueous malonate suggest at least one of the sorbed malonate species is directly coordinated to surface Fe atoms in an inner-sphere mode. In the presence of Pb, little change is seen in the IR spectrum for sorbed malonate, indicating that geometry of malonate as it coordinates to sorbed Pb(II) adions is similar to the geometry of malonate as it coordinates to Fe in the hematite surface. Fits of the raw EXAFS spectra collected from pH 4 to pH 8 result in average Pb-C distances of 2.98 to 3.14 A??, suggesting the presence of both four- and six-membered Pb-malonate rings. The IR results are consistent with this interpretation. Thus, our results suggest that malonate binds to sorbed Pb(II) adions, forming ternary metal-bridging surface complexes. ?? 2001 Academic Press.

  20. Isothermal Oxidation of Magnetite to Hematite in Air and Cyclic Reduction/Oxidation Under Carbon Looping Combustion Conditions

    Science.gov (United States)

    Simmonds, Tegan; Hayes, Peter C.

    2017-12-01

    In the carbon looping combustion process the oxygen carrier is regenerated through oxidation in air; this process has been simulated by the oxidation of dense synthetic magnetite for selected temperatures and times. The oxidation of magnetite in air is shown to occur through the formation of dense hematite layers on the particle surface. This dense hematite forms through lath type shear transformations or solid-state diffusion through the product layer. Cyclic reduction in CO-CO2/oxidation in air of hematite single crystals has been carried out under controlled laboratory conditions at 1173 K (900 °C). It has been shown that the initial reduction step is critical to determining the product microstructure, which consists of gas pore dendrites in the magnetite matrix with blocky hematite formed on the pore surfaces. The progressive growth of the magnetite layer with the application of subsequent cycles appears to continue until no original hematite remains, after which physical disintegration of the particles takes place.

  1. Synthesis of Ru doped hematite nanorods for application as photo-anode material in a photoelectrochemical cell (PEC)

    Energy Technology Data Exchange (ETDEWEB)

    Ndlangamandla, C. L. [University of Zululand, Department of Physics and Engineering (South Africa); Bharuth-Ram, K., E-mail: kbr@tlabs.ac.za [Durban University of Technology, Physics Department (South Africa); Ngom, B. D.; Maaza, M. [iThemba LABS, Materials Research Department (South Africa)

    2017-11-15

    Nanostructured thin films of hematite doped with different concentrations of ruthenium were grown on fluorine doped tin oxide glass substrates using the aqueous chemical growth method. On further heat treatment at 500 {sup ∘}C the structures morphed into hematite nanorods (NRs). The Ru concentration in the NRs was controlled by varying the Ru concentration in the RuCl {sub 3}⋅H{sub 2}O precursors. Scanning Electron Microscopy confirmed the formation of the hematite nanorods, while. X-ray diffraction and Mössbauer spectroscopy (MS) data provided clear evidence of the crystallinity of the nanorods and incorporation of ruthenium in the hematite nanorod structure. The band gap of the Ru-doped hematite NRs, estimated from UV-Vis optical absorption intensity vs photon energy curves, were found to be directly related to the Ru concentration. For concentrations in the range 6–30 mg the band gaps are in the range well suited to drive the water splitting process in a photoelectrochemical cell without application of an external bias.

  2. Effect of defects on the small polaron formation and transport properties of hematite from first-principles calculations.

    Science.gov (United States)

    Smart, Tyler J; Ping, Yuan

    2017-10-04

    Hematite (α-Fe 2 O 3 ) is a promising candidate as a photoanode material for solar-to-fuel conversion due to its favorable band gap for visible light absorption, its stability in an aqueous environment and its relatively low cost in comparison to other prospective materials. However, the small polaron transport nature in α-Fe 2 O 3 results in low carrier mobility and conductivity, significantly lowering its efficiency from the theoretical limit. Experimentally, it has been found that the incorporation of oxygen vacancies and other dopants, such as Sn, into the material appreciably enhances its photo-to-current efficiency. Yet no quantitative explanation has been provided to understand the role of oxygen vacancy or Sn-doping in hematite. We employed density functional theory to probe the small polaron formation in oxygen deficient hematite, N-doped as well as Sn-doped hematite. We computed the charged defect formation energies, the small polaron formation energy and hopping activation energies to understand the effect of defects on carrier concentration and mobility. This work provides us with a fundamental understanding regarding the role of defects on small polaron formation and transport properties in hematite, offering key insights into the design of new dopants to further improve the efficiency of transition metal oxides for solar-to-fuel conversion.

  3. Metalliferous sediment and a silica-hematite deposit within the Blanco fracture zone, Northeast Pacific

    Science.gov (United States)

    Hein, J.R.; Clague, D.A.; Koski, R.A.; Embley, R.W.; Dunham, R.E.

    2008-01-01

    A Tiburon ROV dive within the East Blanco Depression (EBD) increased the mapped extent of a known hydrothermal field by an order of magnitude. In addition, a unique opal-CT (cristobalite-tridymite)-hematite mound was discovered, and mineralized sediments and rock were collected and analyzed. Silica-hematite mounds have not previously been found on the deep ocean floor. The light-weight rock of the porous mound consists predominantly of opal-CT and hematite filaments, rods, and strands, and averages 77.8% SiO2 and 11.8% Fe2O3. The hematite and opal-CT precipitated from a low-temperature (???115?? C), strongly oxidized, silica- and iron-rich, sulfur-poor hydrothermal fluid; a bacterial mat provided the framework for precipitation. Samples collected from a volcaniclastic rock outcrop consist primarily of quartz with lesser plagioclase, smectite, pyroxene, and sulfides; SiO2 content averages 72.5%. Formation of these quartz-rich samples is best explained by cooling in an up-flow zone of silica-rich hydrothermal fluids within a low permeability system. Opal-A, opal-CT, and quartz mineralization found in different places within the EBD hydrothermal field likely reflects decreasing silica saturation and increasing temperature of the mineralizing fluid with increasing silica crystallinity. Six push cores recovered gravel, coarse sand, and mud mineralized variously by Fe or Mn oxides, silica, and sulfides. Total rare-earth element concentrations are low for both the rock and push core samples. Ce and Eu anomalies reflect high and low temperature hydrothermal components and detrital phases. A remarkable variety of types of mineralization occur within the EBD field, yet a consistent suite of elements is enriched (relative to basalt and unmineralized cores) in all samples analyzed: Ag, Au, S, Mo, Hg, As, Sb, Sr, and U; most samples are also enriched in Cu, Pb, Cd, and Zn. On the basis of these element enrichments, the EBD hydrothermal field might best be described as a base

  4. Pressure response of vacancy ordered maghemite (γ-Fe2O3) and high pressure transformed hematite (α-Fe2O3)

    International Nuclear Information System (INIS)

    Hearne, Giovanni; Pischedda, Vittoria

    2012-01-01

    Combined XRD and Mössbauer effect spectroscopy studies to high pressures of ∼30 GPa of vacancy ordered maghemite are presented. The vacancy ordered superstructure is robust and remains intact up to the pressure-induced onset transition to hematite at 13–16 GPa. The pressure transformed hematite is shown to be crystallographically textured, unlike the randomised low pressure maghemite phase. This arises out of a pressure or stress instigated topotactic transformation of the cubic-spinel to hexagonal-corundum structure. The textured sample permits us to obtain information on the spin reorientation behavior of the pressure transformed hematite in compression and decompression sequences. Spin reorientation is restricted to ∼15° over wide pressure ranges, attributable to the effect of entrapped vacancies in the high pressure structure. Thus there are structural and magnetic peculiarities specific to pressure transformed hematite not evident in pressurized hematite starting material. These are triggered by the maghemite→hematite transformation. - Graphical abstract: Pressure instigated topotactic transformation of vacancy ordered γ-Fe 2 O 3 →α-Fe 2 O 3 . There is restricted spin (B hf ) reorientation in the new pressure transformed hematite due to entrapped vacancies. The change in direction of V zz signifies a distortion of the FeO 6 octahedral local environment. Highlights: ► Robust vacancy ordered superstructure in maghemite to high pressures. ► Pressure instigated topotactic transformation to hematite and subsequent texture. ► Defect trapping in the pressure transformed hematite. ► Entrapped defects restricts spin reorientation in pressure transformed hematite. ► Contrasting behavior with pressurized hematite starting material.

  5. Prolate spheroidal hematite particles equatorially belt with drug-carrying layered double hydroxide disks: Ring Nebula-like nanocomposites

    Directory of Open Access Journals (Sweden)

    Nedim Ay Ahmet

    2011-01-01

    Full Text Available Abstract A new nanocomposite architecture is reported which combines prolate spheroidal hematite nanoparticles with drug-carrying layered double hydroxide [LDH] disks in a single structure. Spindle-shaped hematite nanoparticles with average length of 225 nm and width of 75 nm were obtained by thermal decomposition of hydrothermally synthesized hematite. The particles were first coated with Mg-Al-NO3-LDH shell and then subjected to anion exchange with salicylate ions. The resulting bio-nanohybrid displayed a close structural resemblance to that of the Ring Nebula. Scanning electron microscope and transmission electron microscopy images showed that the LDH disks are stacked around the equatorial part of the ellipsoid extending along the main axis. This geometry possesses great structural tunability as the composition of the LDH and the nature of the interlayer region can be tailored and lead to novel applications in areas ranging from functional materials to medicine by encapsulating various guest molecules.

  6. Prolate spheroidal hematite particles equatorially belt with drug-carrying layered double hydroxide disks: Ring Nebula-like nanocomposites.

    Science.gov (United States)

    Nedim Ay, Ahmet; Konuk, Deniz; Zümreoglu-Karan, Birgul

    2011-02-03

    A new nanocomposite architecture is reported which combines prolate spheroidal hematite nanoparticles with drug-carrying layered double hydroxide [LDH] disks in a single structure. Spindle-shaped hematite nanoparticles with average length of 225 nm and width of 75 nm were obtained by thermal decomposition of hydrothermally synthesized hematite. The particles were first coated with Mg-Al-NO3-LDH shell and then subjected to anion exchange with salicylate ions. The resulting bio-nanohybrid displayed a close structural resemblance to that of the Ring Nebula. Scanning electron microscope and transmission electron microscopy images showed that the LDH disks are stacked around the equatorial part of the ellipsoid extending along the main axis. This geometry possesses great structural tunability as the composition of the LDH and the nature of the interlayer region can be tailored and lead to novel applications in areas ranging from functional materials to medicine by encapsulating various guest molecules.

  7. Anorexia nervosa in light of Karl Jaspers and Erich Fromm’s ideas and social constructivism – hypotheses and thoughts [Anoreksja psychiczna z perspektywy koncepcji Karla Jaspersa, Ericha Fromma oraz nurtu konstrukcjonizmu społecznego – hipotezy i refleksje

    OpenAIRE

    Talarczyk, Małgorzata

    2012-01-01

    e point of the article is to analyse and reflect on certain symptoms of anorexia nervosa in light of Karl Jaspers and Erich Fromm’s ideas and social constructivism. Contemplating the disorder in view of the philosophical ideas mentioned earlier, the author analyses such aspects of patients as: functioning on the verge of life and death, the paradoxical struggle to escape from freedom in search of independence, as well as various understandings and descriptions of anorexia in consideration of ...

  8. Karl Jaspers y la distinción hermenéutica entre entender y explicar en psicopatología. ¿Podríamos reencontrarnos en alguien que padeciera el síndrome de Cotard tipo I?

    OpenAIRE

    Ariso Salgado, José María (UNIR)

    2011-01-01

    Though Karl Jaspers stated in his General Psychopathology that the genesis of delusions is un-understandable rational and empathically, millions of people all over the world and lots of cinema critics seem to have understood in both ways the genesis of the case of Cotard syndrome which appears by the end of the film The Sixth Sense (1999). In this paper, however, I will show that the possibility of understanding rational and empathically the genesis of this case is just unrealisti...

  9. Hematite Nanoparticles-Modified Electrode Based Electrochemical Sensing Platform for Dopamine

    Science.gov (United States)

    Zangeneh Kamali, Khosro; Alagarsamy, Pandikumar; Huang, Nay Ming; Ong, Boon Hoong; Lim, Hong Ngee

    2014-01-01

    Hematite (α-Fe2O3) nanoparticles were synthesized by the solid transformation of ferrous hydroxide and ferrihydrite in hydrothermal condition. The as-prepared α-Fe2O3 nanoparticles were characterized by UV-vis, PL, XRD, Raman, TEM, AFM, FESEM, and EDX analysis. The experimental results indicated the formation of uniform hematite nanoparticles with an average size of 45 nm and perfect crystallinity. The electrochemical behavior of a GC/α-Fe2O3 electrode was studied using CV and EIS techniques with an electrochemical probe, [Fe(CN)6]3−/4− redox couple. The electrocatalytic activity was investigated toward DA oxidation in a phosphate buffer solution (pH 6.8) by varying different experimental parameters. The chronoamperometric study showed a linear response in the range of 0–2 μM with LoD of 1.6 μM for DA. Square wave voltammetry showed a linear response in the range of 0–35 μM with LoD of 236 nM for DA. PMID:25136664

  10. Low-cost superior solid-state symmetric supercapacitors based on hematite nanocrystals

    Science.gov (United States)

    Peng, Shaomin; Yu, Lin; Lan, Bang; Sun, Ming; Cheng, Gao; Liao, Shuhuan; Cao, Han; Deng, Yulin

    2016-12-01

    We present a facile method for the fabrication of hematite nanocrystal-carbon cloth (Fe2O3-CC) composite. Hierarchical manganite is chosen as the sacrificial precursor, that does not contribute to the component of final iron oxide but can be in situ dissolved by the acid produced from the Fe3+ hydrolysis. This method effectively enhances the specific surface area and conductivity of hematite (Fe2O3) by attaching Fe2O3 nanocrystals (around 5 nm) firmly on the surface of carbon fibers. The obtained Fe2O3-CC can be directly used as a binder-free electrode for a supercapacitor. Interestingly, the composite electrode exhibits synergistic electrochemical capacitance (electrochemical double-layer capacitance and pseudo-capacitance). It manifests a very high areal capacitance of 1.66 F cm-2 (1660 F g-1) at 2 mA cm-2 and excellent cycling performance at large current densities (88.6% retention at 30 mA cm-2 after 5000 cycles) in a three-electrode testing system, which is among the best performances reported in the literature. Importantly, when fabricated as a solid-state flexible symmetric supercapacitor it still shows a maximum energy density of 8.74 mW h cm-3 and power density of 253.9 mW cm-3. Additionally, its good flexibility makes it suitable for portable devices.

  11. Hematite Nanoparticles-Modified Electrode Based Electrochemical Sensing Platform for Dopamine

    Directory of Open Access Journals (Sweden)

    Khosro Zangeneh Kamali

    2014-01-01

    Full Text Available Hematite (α-Fe2O3 nanoparticles were synthesized by the solid transformation of ferrous hydroxide and ferrihydrite in hydrothermal condition. The as-prepared α-Fe2O3 nanoparticles were characterized by UV-vis, PL, XRD, Raman, TEM, AFM, FESEM, and EDX analysis. The experimental results indicated the formation of uniform hematite nanoparticles with an average size of 45 nm and perfect crystallinity. The electrochemical behavior of a GC/α-Fe2O3 electrode was studied using CV and EIS techniques with an electrochemical probe, [Fe(CN6]3−/4− redox couple. The electrocatalytic activity was investigated toward DA oxidation in a phosphate buffer solution (pH 6.8 by varying different experimental parameters. The chronoamperometric study showed a linear response in the range of 0–2 μM with LoD of 1.6 μM for DA. Square wave voltammetry showed a linear response in the range of 0–35 μM with LoD of 236 nM for DA.

  12. Reversibility of sorption of plutonium-239 onto hematite and goethite colloids

    International Nuclear Information System (INIS)

    Lu, N.; Cotter, C.R.; Kitten, H.D.; Bentley, J.; Triay, I.R.

    1998-01-01

    Laboratory batch sorption experiments were conducted to evaluate: (1) sorption of plutonium-239 ( 239 Pu) on different iron oxide colloids (hematite and geothite), (2) sorption kinetics of colloidal Pu(IV) and soluble Pu(V) onto these two colloids, and (3) desorption of colloidal Pu(IV) and soluble Pu(V) from 239 Pu-loaded colloids as a function of time. Natural groundwater and carbonate-rich synthetic groundwater were used in this study. To examine the possible influence of bicarbonate on 239 Pu sorption, an additional set of experiments was conducted in sodium nitrate (NaNO 3 ) solutions under carbon dioxide free environments. Our results show that colloidal Pu(IV) as well as soluble Pu(V) was rapidly adsorbed by hematite and goethite colloids in both natural and synthetic groundwater. The amount of 239 Pu adsorbed by both iron oxide colloids in synthetic groundwater was higher than in natural groundwater. The presence of carbonate did not influence the sorption of 239 Pu. While sorption of soluble Pu(V) is a slow process, sorption of colloidal Pu(IV) occurs rapidly. Desorption of Pu from iron oxide colloids is much slower than the sorption processes. Our findings suggest that different sorption and desorption behaviors of 239 Pu by iron oxide colloids in groundwater may facilitate the transport of 239 Pu along potential flowpaths from the areas contaminated by radionuclide and release to the accessible environment. (orig.)

  13. Synthesis and characterization of hematite pigment obtained from a steel waste industry.

    Science.gov (United States)

    Prim, S R; Folgueras, M V; de Lima, M A; Hotza, D

    2011-09-15

    Pigments that meet environmental and technology requirements are the focus of the research in the ceramic sector. This study focuses on the synthesis of ceramic pigment by encapsulation of hematite in crystalline and amorphous silica matrix. Iron oxide from a metal sheet rolling process was used as chromophore. A different content of hematite and silica was homogenized by conventional and high energy milling. The powders obtained after calcinations between 1050 and 1200 °C for 2h were characterized by X-ray diffraction and SEM analysis. The pigments were applied to ceramic enamel and porcelain body. The effect of pigment was measured by comparing L*a*b* values of the heated samples. Results showed that the color developed is influenced by variables such as oxide content employed, conditions of milling and processing temperature. The results showed that the use of pigment developed does not interfere in microstructural characteristics of pigmented material. The best hue was obtained from samples with 15 wt% of chromophore, heated at 1200 °C in amorphous silica matrix. Copyright © 2011 Elsevier B.V. All rights reserved.

  14. Interaction of Zn(II) with hematite nanoparticles and microparticles: Part 2. ATR-FTIR and EXAFS study of the aqueous Zn(II)/oxalate/hematite ternary system.

    Science.gov (United States)

    Ha, Juyoung; Trainor, Thomas P; Farges, François; Brown, Gordon E

    2009-05-19

    Sorption of Zn(II) to hematite nanoparticles (HN) (av diam=10.5 nm) and microparticles (HM) (av diam=550 nm) was studied in the presence of oxalate anions (Ox2-(aq)) in aqueous solutions as a function of total Zn(II)(aq) to total Ox2-(aq) concentration ratio (R=[Zn(II)(aq)]tot/[Ox2-(aq)]tot) at pH 5.5. Zn(II) uptake is similar in extent for both the Zn(II)/Ox/HN and Zn(II)/Ox/HM ternary systems and the Zn(II)/HN binary system at [Zn(II)(aq)](tot)system than for the Zn(II)/Ox/HM ternary and the Zn(II)/HN and Zn(II)/HM binary systems at [Zn(II)(aq)]tot>4 mM. In contrast, Zn(II) uptake for the Zn(II)/HM binary system is a factor of 2 greater than that for the Zn(II)/Ox/HM and Zn(II)/Ox/HN ternary systems and the Zn(II)/HN binary system at [Zn(II)(aq)]totternary system at both R values examined (0.16 and 0.68), attenuated total reflectance Fourier transform infrared (ATR-FTIR) results are consistent with the presence of inner-sphere oxalate complexes and outer-sphere ZnOx(aq) complexes, and/or type A ternary complexes. In addition, extended X-ray absorption fine structure (EXAFS) spectroscopic results suggest that type A ternary surface complexes (i.e., >O2-Zn-Ox) are present. In the Zn(II)/Ox/HN ternary system at R=0.15, ATR-FTIR results indicate the presence of inner-sphere oxalate and outer-sphere ZnOx(aq) complexes; the EXAFS results provide no evidence for inner-sphere Zn(II) complexes or type A ternary complexes. In contrast, ATR-FTIR results for the Zn/Ox/HN sample with R = 0.68 are consistent with a ZnOx(s)-like surface precipitate and possibly type B ternary surface complexes (i.e., >O2-Ox-Zn). EXAFS results are also consistent with the presence of ZnOx(s)-like precipitates. We ascribe the observed increase of Zn(II)(aq) uptake in the Zn(II)/Ox/HN ternary system at [Zn(II)(aq)]tot>or=4 mM relative to the Zn(II)/Ox/HM ternary system to formation of a ZnOx(s)-like precipitate at the hematite nanoparticle/water interface.

  15. The application of Lorentz transmission electron microscopy to the study of lamellar magnetism in hematite-ilmenite

    DEFF Research Database (Denmark)

    Kasama, Takeshi; Dunin-Borkowski, Rafal E.; Asaka, T

    2009-01-01

    . However, the magnitude of the experimental contrast is higher than that in the simulations, suggesting that an alternative origin for the observed asymmetry cannot be ruled out. Electron tomography was used to show that the lamellae have lens-like shapes and that (001) planes make up a significant...... in hematite. The likelihood that lamellar magnetism may be responsible for this contrast is assessed using simulations that incorporate interfacial magnetic moments on the (001) basal planes of hematite and ilmenite. The simulations suggest qualitatively that the asymmetric contrast is magnetic in origin...

  16. Paleomycology of the Princeton Chert. III. Dictyosporic microfungi, Monodictysporites princetonensis gen. et sp. nov., associated with decayed rhizomes of an Eocene semi-aquatic fern.

    Science.gov (United States)

    Klymiuk, Ashley A

    2016-09-01

    This study builds on previous investigations of paleomycological diversity within permineralized plants of a significant Eocene paleobotanical locality, the Princeton Chert. The fungal body fossils described here occur in decayed rhizomes of the extinct semi-aquatic fern Dennstaedtiopsis aerenchymata Fungi include vegetative hyphae throughout the plant tissue, as well as a dense assemblage of >100 dematiaceous spores. The spores occur in a discrete zone surrounding two extraneous rootlets of other plants, which penetrated the fern tissue post-mortem. Spores are obovoid and muriform, composed of 8-12 cells with constricted septa and produced from hyaline or slightly pigmented hyphae. The spores are morphologically similar to both asexual reproductive dictyospores of phylogenetically disparate microfungi attributed to the morphogenus Monodictys and perennating dictyochlamydospores that occur in the anamorph genus Phoma In addition to expanding the early Eocene fossil record for Ascomycota, these specimens also provide new insight into the rapidity of initial phases of the fossilization process in this important paleobotanical locality. © 2016 by The Mycological Society of America.

  17. Mechanism of Methane Chemical Looping Combustion with Hematite Promoted with CeO 2

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Duane D.; Siriwardane, Ranjani

    2013-08-15

    Chemical looping combustion (CLC) is a promising technology for fossil fuel combustion that produces sequestration-ready CO{sub 2} stream, reducing the energy penalty of CO{sub 2} separation from flue gases. An effective oxygen carrier for CLC will readily react with the fuel gas and will be reoxidized upon contact with oxygen. This study investigated the development of a CeO{sub 2}-promoted Fe{sub 2}O{sub 3}-hematite oxygen carrier suitable for the methane CLC process. Composition of CeO{sub 2} is between 5 and 25 wt % and is lower than what is generally used for supports in Fe{sub 2}O{sub 3} carrier preparations. The incorporation of CeO{sub 2} to the natural ore hematite strongly modifies the reduction behavior in comparison to that of CeO{sub 2} and hematite alone. Temperature-programmed reaction studies revealed that the addition of even 5 wt % CeO{sub 2} enhances the reaction capacity of the Fe{sub 2}O{sub 3} oxygen carrier by promoting the decomposition and partial oxidation of methane. Fixed-bed reactor data showed that the 5 wt % cerium oxides with 95 wt % iron oxide produce 2 times as much carbon dioxide in comparison to the sum of carbon dioxide produced when the oxides were tested separately. This effect is likely due to the reaction of CeO{sub 2} with methane forming intermediates, which are reactive for extracting oxygen from Fe{sub 2}O{sub 3} at a considerably faster rate than the rate of the direct reaction of Fe{sub 2}O{sub 3} with methane. These studies reveal that 5 wt % CeO{sub 2}/Fe{sub 2}O{sub 3} gives stable conversions over 15 reduction/oxidation cycles. Lab-scale reactor studies (pulsed mode) suggest the methane reacts initially with CeO{sub 2} lattice oxygen to form partial oxidation products (CO + H{sub 2}), which continue to react with oxygen from neighboring Fe{sub 2}O{sub 3}, leading to its complete oxidation to form CO{sub 2}. The reduced cerium oxide promotes the methane decomposition reaction to form C + H{sub 2}, which continue to

  18. Hematite Spherules in Basaltic Tephra Altered Under Aqueous, Acid-Sulfate Conditions on Mauna Kea Volcano, Hawaii: Possible Clues for the Occurrence of Hematite-Rich Spherules in the Burns Formation at Meridiani Planum, Mars

    Science.gov (United States)

    Morris, R. V.; Ming, D. W.; Graff, T. G.; Arvidson, R. E.; Bell, J. F., III; Squyres, S. W.; Mertzman, S. A.; Gruener, J. E.; Golden, D. C.; Robinson, G. A.

    2005-01-01

    Iron-rich spherules (>90% Fe2O3 from electron microprobe analyses) approx.10-100 microns in diameter are found within sulfate-rich rocks formed by aqueous, acid-sulfate alteration of basaltic tephra on Mauna Kea volcano, Hawaii. Although some spherules are nearly pure Fe, most have two concentric compositional zones, with the core having a higher Fe/Al ratio than the rim. Oxide totals less than 100% (93-99%) suggest structural H2O and/or /OH. The transmission Moessbauer spectrum of a spherule-rich separate is dominated by a hematite (alpha-Fe2O3) sextet whose peaks are skewed toward zero velocity. Skewing is consistent with Al(3+) for Fe(3+) substitution and structural H2O and/or /OH. The grey color of the spherules implies specular hematite. Whole-rock powder X-ray diffraction spectra are dominated by peaks from smectite and the hydroxy sulfate mineral natroalunite as alteration products and plagioclase feldspar that was present in the precursor basaltic tephra. Whether spherule formation proceeded directly from basaltic material in one event (dissolution of basaltic material and precipitation of hematite spherules) or whether spherule formation required more than one event (formation of Fe-bearing sulfate rock and subsequent hydrolysis to hematite) is not currently constrained. By analogy, a formation pathway for the hematite spherules in sulfate-rich outcrops at Meridiani Planum on Mars (the Burns formation) is aqueous alteration of basaltic precursor material under acid-sulfate conditions. Although hydrothermal conditions are present on Mauna Kea, such conditions may not be required for spherule formation on Mars if the time interval for hydrolysis at lower temperatures is sufficiently long.

  19. Liquid Adsorption of Organic Compounds on Hematite α-Fe2O3 Using ReaxFF.

    Science.gov (United States)

    Chia, Chung-Lim; Avendaño, Carlos; Siperstein, Flor R; Filip, Sorin

    2017-10-24

    ReaxFF-based molecular dynamics simulations are used in this work to study the effect of the polarity of adsorbed molecules in the liquid phase on the structure and polarization of hematite (α-Fe 2 O 3 ). We compared the adsorption of organic molecules with different polarities on a rigid hematite surface and on a flexible and polarizable surface. We show that the displacements of surface atoms and surface polarization in a flexible hematite model are proportional to the adsorbed molecule's polarity. The increase in electrostatic interactions resulting from charge transfer in the outermost solid atoms in a flexible hematite model results in better-defined adsorbed layers that are less ordered than those obtained assuming a rigid solid. These results suggest that care must be taken when parametrizing empirical transferable force fields because the calculated charges on a solid slab in vacuum may not be representative of a real system, especially when the solid is in contact with a polar liquid.

  20. Natural Hematite and Siderite as Heterogeneous Catalysts for an Effective Degradation of 4-Chlorophenol via Photo-Fenton Process

    Directory of Open Access Journals (Sweden)

    Haithem Bel Hadjltaief

    2018-06-01

    Full Text Available This paper describes a simple and low-cost process for the degradation of 4-Chlorophenol (4-CP from aqueous solution, using natural Tunisian Hematite (M1 and Siderite (M2. Two natural samples were collected in the outcroppings of the Djerissa mining site (Kef district, northwestern Tunisia. Both Hematite and Siderite ferrous samples were characterized using several techniques, including X-Ray Diffraction (XRD, Nitrogen Physisorption (BET, Infrared Spectroscopy (FTIR, H2-Temperature Programmed Reduction (H2-TPR, Scanning Electronic Microscopy (SEM linked with Energy Dispersive X-ray (EDS and High-Resolution Transmission Electron Microscopy (HRTEM. Textural, structural and chemical characterization confirmed the presence of Hematite and Siderite phases with a high amount of iron on the both surface materials. Their activity was evaluated in the oxidation of 4-CP in aqueous medium under heterogeneous photo-Fenton process. Siderite exhibited higher photocatalytic oxidation activity than Hematite at pH 3. The experimental results also showed that 100% conversion of 4-CP and 54% TOC removal can be achieved using Siderite as catalyst. Negligible metal leaching and catalyst reutilization without any loss of activity point towards an excellent catalytic stability for both natural catalysts.

  1. Role of Ion Bombardment, Film Thickness and Temperature of Annealing on PEC Activity of Very-thin Film Hematite .

    Czech Academy of Sciences Publication Activity Database

    Kment, Š.; Čada, M.; Hubička, Z.; Krýsa, J.; Kmentová, Hana; Olejníček, J.; Zlámalová Cílová, Z.; Zbořil, R.

    2016-01-01

    Roč. 41, č. 27 (2016), s. 11547-11557 ISSN 0360-3199. [International Conference on Hydrogen Energy /1./. Aveiro, 20.07.2015-22.07.2015] Institutional support: RVO:67985858 Keywords : ion flux density * hematite photoanode * thin films Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.582, year: 2016

  2. Characteristics of NixFe1−xOy Electrocatalyst on Hematite as Photoanode for Solar Hydrogen Production

    Directory of Open Access Journals (Sweden)

    Chih-Ping Yen

    2017-11-01

    Full Text Available The use of hematite as the photoanode for photoelectrochemical hydrogen production by solar energy has been actively studied due to its abundance, stability, and adequate optical properties. Deposition of an electrocatalyst overlayer on the hematite may increase kinetics and lower the onset potential for water splitting. NixFe1−xOy is one of the most effective electrocatalysts reported for this purpose. However, the condition and results of the previous reports vary significantly, and a comprehensive model for NixFe1−xOy/hematite is lacking. Here, we report a simple and novel chemical bath deposition method for depositing low-onset-potential NixFe1−xOy electrocatalyst on hematite. With a Ni percentage of 80% and an immersion time of 2 min, the as-prepared NixFe1−xOy overlayer raised the photovoltage from 0.2 V to 0.7 V, leading to a cathodic shift of the onset potential by 400 mV, while maintaining the same level of current density. The dependence of the electrochemical and photoelectrochemical characteristics of the photoanode on the condition of the electrocatalyst was studied systematically and explained based on energy level diagrams and kinetics.

  3. Photoanodes with fully controllable texture: the enhanced water splitting efficiency of thin hematite films exhibiting solely (110) crystal orientation

    Czech Academy of Sciences Publication Activity Database

    Kment, Š.; Schmuki, P.; Hubička, Zdeněk; Machala, L.; Kirchgeorg, R.; Liu, N.; Wang, L.; Lee, K.; Olejníček, Jiří; Čada, Martin; Gregora, Ivan; Zbořil, R.

    2015-01-01

    Roč. 9, č. 7 (2015), s. 7113-7123 ISSN 1936-0851 R&D Projects: GA MŠk LH12043 Institutional support: RVO:68378271 Keywords : hematite * iron oxide * texture * PEC water splitting * pulsed magnetron sputtering * conversion electron Mössbauer spectroscopy Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 13.334, year: 2015

  4. Compact hematite buffer layer as a promoter of nanorod photoanode performances

    Science.gov (United States)

    Milan, R.; Cattarin, S.; Comisso, N.; Baratto, C.; Kaunisto, K.; Tkachenko, N. V.; Concina, I.

    2016-10-01

    The effect of a thin α-Fe2O3 compact buffer layer (BL) on the photoelectrochemical performances of a bare α-Fe2O3 nanorods photoanode is investigated. The BL is prepared through a simple spray deposition onto a fluorine-doped tin oxide (FTO) conducting glass substrate before the growth of a α-Fe2O3 nanorods via a hydrothermal process. Insertion of the hematite BL between the FTO and the nanorods markedly enhances the generated photocurrent, by limiting undesired losses of photogenerated charges at the FTO||electrolyte interface. The proposed approach warrants a marked improvement of material performances, with no additional thermal treatment and no use/dispersion of rare or toxic species, in agreement with the principles of green chemistry.

  5. Nanocrack Formation in Hematite through the Dehydration of Goethite and the Carbon Infiltration from Biotar

    Directory of Open Access Journals (Sweden)

    Yoshiaki Kashiwaya

    2010-01-01

    Full Text Available The cracks in nano-order are generated and propagated when the combined water is released during the dehydration. If the nanopore can be utilized for a reaction site, the overall reaction can be extremely accelerated. On the other hand, it is well known that woody biomass is an attractive alternative fuel for the reduction of CO2 emission. However, the process of biomass pyrolysis is disturbed by the tar which causes a clogging in gas tubing system. Hata et al. found that the tar was consumed almost 100% in the iron ore layer having nanocrack or nanopore. The nanocracks formed in hematite crystals after dehydration of goethite were about 4 nm in width, which is in excellent agreement with the result of BET measurement. When the carbon deposited from tar into the nanocracks, reduction reactions were occurred simultaneously. The deposited carbons completely infilled into the nanocracks and the void in the sample.

  6. Passivating surface states on water splitting hematite photoanodes with alumina overlayers

    KAUST Repository

    Le Formal, Florian; Té treault, Nicolas; Cornuz, Maurin; Moehl, Thomas; Grä tzel, Michael; Sivula, Kevin

    2011-01-01

    Hematite is a promising material for inexpensive solar energy conversion via water splitting but has been limited by the large overpotential (0.5-0.6 V) that must be applied to afford high water oxidation photocurrent. This has conventionally been addressed by coating it with a catalyst to increase the kinetics of the oxygen evolution reaction. However, surface recombination at trapping states is also thought to be an important factor for the overpotential, and herein we investigate a strategy to passivate trapping states using conformal overlayers applied by atomic layer deposition. While TiO2 overlayers show no beneficial effect, we find that an ultra-thin coating of Al2O3 reduces the overpotential required with state-of-the-art nano-structured photo-anodes by as much as 100 mV and increases the photocurrent by a factor of 3.5 (from 0.24 mA cm-2 to 0.85 mA cm-2) at +1.0 V vs. the reversible hydrogen electrode (RHE) under standard illumination conditions. The subsequent addition of Co2+ ions as a catalyst further decreases the overpotential and leads to a record photocurrent density at 0.9 V vs. RHE (0.42 mA cm-2). A detailed investigation into the effect of the Al2O3 overlayer by electrochemical impedance and photoluminescence spectroscopy reveals a significant change in the surface capacitance and radiative recombination, respectively, which distinguishes the observed overpotential reduction from a catalytic effect and confirms the passivation of surface states. Importantly, this work clearly demonstrates that two distinct loss processes are occurring on the surface of high-performance hematite and suggests a viable route to individually address them. © The Royal Society of Chemistry 2011.

  7. Linking interfacial chemistry of CO2 to surface structures of hydrated metal oxide nanoparticles: hematite.

    Science.gov (United States)

    Chernyshova, Irina V; Ponnurangam, Sathish; Somasundaran, Ponisseril

    2013-05-14

    A better understanding of interaction with dissolved CO2 is required to rationally design and model the (photo)catalytic and sorption processes on metal (hydr)oxide nanoparticles (NPs) in aqueous media. Using in situ FTIR spectroscopy, we address this problem for rhombohedral 38 nm hematite (α-Fe2O3) nanoparticles as a model. We not only resolve the structures of the adsorbed carbonate species, but also specify their adsorption sites and their location on the nanoparticle surface. The spectral relationships obtained present a basis for a new method of characterizing the microscopic structural and acid-base properties (related to individual adsorption sites) of hydrated metal (hydr)oxide NPs using atmospherically derived CO2 as a probe. Specifically, we distinguish two carbonate species suggesting two principally different adsorption mechanisms. One species, which is more weakly adsorbed, has an inner-sphere mononuclear monodentate structure which is formed by a conventional ligand-exchange mechanism. At natural levels of dissolved carbonate and pH from 3 to 11, this species is attached to the most acidic/reactive surface cations (surface states) associated with ferrihydrite-like surface defects. The second species, which is more strongly adsorbed, presents a mixed C and O coordination of bent CO2. This species uniquely recognizes the stoichiometric rhombohedral {104} facets in the NP texture. Like in gas phase, it is formed through the surface coordination of molecular CO2. We address how the adsorption sites hosting these two carbonate species are affected by the annealing and acid etching of the NPs. These results support the nanosize-induced phase transformation of hematite towards ferrihydrite under hydrous conditions, and additionally show that the process starts from the roughened areas of the facet intersections.

  8. Chemical Looping Combustion of Hematite Ore with Methane and Steam in a Fluidized Bed Reactor

    Directory of Open Access Journals (Sweden)

    Samuel Bayham

    2017-08-01

    Full Text Available Chemical looping combustion is considered an indirect method of oxidizing a carbonaceous fuel, utilizing a metal oxide oxygen carrier to provide oxygen to the fuel. The advantage is the significantly reduced energy penalty for separating out the CO2 for reuse or sequestration in a carbon-constrained world. One of the major issues with chemical looping combustion is the cost of the oxygen carrier. Hematite ore is a proposed oxygen carrier due to its high strength and resistance to mechanical attrition, but its reactivity is rather poor compared to tailored oxygen carriers. This problem is further exacerbated by methane cracking, the subsequent deposition of carbon and the inability to transfer oxygen at a sufficient rate from the core of the particle to the surface for fuel conversion to CO2. Oxygen needs to be readily available at the surface to prevent methane cracking. The purpose of this work was to demonstrate the use of steam to overcome this issue and improve the conversion of the natural gas to CO2, as well as to provide data for computational fluid dynamics (CFD validation. The steam will gasify the deposited carbon to promote the methane conversion. This work studies the performance of hematite ore with methane and steam mixtures in a 5 cm fluidized bed up to approximately 140 kPa. Results show an increased conversion of methane in the presence of steam (from 20–45% without steam to 60–95% up to a certain point, where performance decreases. Adding steam allows the methane conversion to carbon dioxide to be similar to the overall methane conversion; it also helped to prevent carbon accumulation from occurring on the particle. In general, the addition of steam to the feed gas increased the methane conversion. Furthermore, the addition of steam caused the steam methane reforming reaction to form more hydrogen and carbon monoxide at higher steam and methane concentrations, which was not completely converted at higher concentrations and

  9. Passivating surface states on water splitting hematite photoanodes with alumina overlayers

    KAUST Repository

    Le Formal, Florian

    2011-01-24

    Hematite is a promising material for inexpensive solar energy conversion via water splitting but has been limited by the large overpotential (0.5-0.6 V) that must be applied to afford high water oxidation photocurrent. This has conventionally been addressed by coating it with a catalyst to increase the kinetics of the oxygen evolution reaction. However, surface recombination at trapping states is also thought to be an important factor for the overpotential, and herein we investigate a strategy to passivate trapping states using conformal overlayers applied by atomic layer deposition. While TiO2 overlayers show no beneficial effect, we find that an ultra-thin coating of Al2O3 reduces the overpotential required with state-of-the-art nano-structured photo-anodes by as much as 100 mV and increases the photocurrent by a factor of 3.5 (from 0.24 mA cm-2 to 0.85 mA cm-2) at +1.0 V vs. the reversible hydrogen electrode (RHE) under standard illumination conditions. The subsequent addition of Co2+ ions as a catalyst further decreases the overpotential and leads to a record photocurrent density at 0.9 V vs. RHE (0.42 mA cm-2). A detailed investigation into the effect of the Al2O3 overlayer by electrochemical impedance and photoluminescence spectroscopy reveals a significant change in the surface capacitance and radiative recombination, respectively, which distinguishes the observed overpotential reduction from a catalytic effect and confirms the passivation of surface states. Importantly, this work clearly demonstrates that two distinct loss processes are occurring on the surface of high-performance hematite and suggests a viable route to individually address them. © The Royal Society of Chemistry 2011.

  10. Synthesis and properties of iridium-doped hematite ({alpha}-Fe{sub 2}O{sub 3})

    Energy Technology Data Exchange (ETDEWEB)

    Krehula, Stjepko, E-mail: krehul@irb.hr [Division of Materials Chemistry, Ruder Boskovic Institute, P.O. Box 180, HR-10002 Zagreb (Croatia); Stefanic, Goran [Division of Materials Chemistry, Ruder Boskovic Institute, P.O. Box 180, HR-10002 Zagreb (Croatia); Zadro, Kreso [Department of Physics, Faculty of Science, University of Zagreb, Bijenicka 32, 10000 Zagreb (Croatia); Kratofil Krehula, Ljerka [Faculty of Chemical Engineering and Technology, University of Zagreb, Marulicev trg 19, 10000 Zagreb (Croatia); Marcius, Marijan; Music, Svetozar [Division of Materials Chemistry, Ruder Boskovic Institute, P.O. Box 180, HR-10002 Zagreb (Croatia)

    2012-12-25

    Highlights: Black-Right-Pointing-Pointer Ir-doped hematites were prepared by heating Ir-doped goethites. Black-Right-Pointing-Pointer Ir-doping in hematite led to an increase in unit cell and a decrease in crystallite size. Black-Right-Pointing-Pointer Ir-doping significantly affected magnetic, infrared and UV-Vis properties of hematite. Black-Right-Pointing-Pointer The Morin transition temperature increased with an increase in Ir-doping. Black-Right-Pointing-Pointer Ir ions brought about changes in the size and shape of the formed hematite particles. - Abstract: The effect of the incorporation of Ir{sup 3+} ions on the properties of {alpha}-Fe{sub 2}O{sub 3} formed by dehydroxylation of {alpha}-FeOOH was investigated using X-ray powder diffraction (XRD), thermogravimetric analysis (TGA), {sup 57}Fe Moessbauer, UV-Vis-NIR and FT-IR spectroscopies, SQUID magnetometer, field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray spectroscopy (EDS). Pure and Ir-doped hematite samples were obtained by heating of pure and Ir-doped goethites ({alpha}-FeOOH) formed by precipitation from mixed Fe(III)-Ir(III) chloride solutions in a highly alkaline medium. The incorporation of Ir{sup 3+} ions into the {alpha}-Fe{sub 2}O{sub 3} structure led to changes in unit-cell dimensions, crystallinity, particle size and shape, as well as changes in the magnetic, infrared and UV-Vis properties. An increase in the temperature of the Morin transition with an increase in Ir-doping was observed by Moessbauer spectroscopy and magnetic measurements.

  11. Pristine and Al-doped hematite printed films as photoanodes of p-type dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Congiu, Mirko, E-mail: mirko.congiu@fc.unesp.br [UNESP–Univ. Estadual Paulista, POSMAT-Programa de Pós-Graduação em Ciência e Tecnologia de Materiais (Brazil); De Marco, Maria L.; Bonomo, Matteo [DC-FC-UNESP–Univ. Estadual Paulista (Brazil); Nunes-Neto, Oswaldo [UNESP–Univ. Estadual Paulista, POSMAT-Programa de Pós-Graduação em Ciência e Tecnologia de Materiais (Brazil); Dini, Danilo [DC-FC-UNESP–Univ. Estadual Paulista (Brazil); Graeff, Carlos F.O. [UNESP–Univ. Estadual Paulista, POSMAT-Programa de Pós-Graduação em Ciência e Tecnologia de Materiais (Brazil)

    2017-01-15

    We hereby propose a non-expensive method for the deposition of pure and Al-doped hematite photoanodes in the configuration of thin films for the application of dye-sensitized solar cells (DSSC). The electrodes have been prepared from hematite nanoparticles that were obtained by thermal degradation of a chemical precursor. The particles have been used in the preparation of a paste, suitable for both screen printing and doctor blade deposition. The paste was then spread on fluorine-doped tin oxide (FTO) to obtain porous hematite electrodes. The electrodes have been sensitized using N3 and D5 dyes and were characterized through current/voltage curves under simulated sun light (1 sun, AM 1.5) with a Pt counter electrode. Al-doping of hematite showed interesting changes in the physical and electrochemical characteristics of sensitized photoanodes since we could notice the growth of AlFe{sub 2}O{sub 4} (hercynite) as a secondary crystal phase into the oxides obtained by firing the mixtures of two chemical precursors at different molar ratios. Pure and Al-doped hematite electrodes have been used in a complete n-type DSSCs. The kinetics of charge transfer through the interface dye/electrolyte was studied and compared to that of a typical p-type DSSC based on NiO photocathodes sensitized with erythrosine B. The results suggest a potential application of both Fe{sub 2}O{sub 3} and Fe{sub 2}O{sub 3}/AlFe{sub 2}O{sub 4} as photoanodes of a tandem DSSC.

  12. Hematite (U-Th)/He thermochronometry constrains intraplate strike-slip faulting on the Kuh-e-Faghan Fault, central Iran

    Science.gov (United States)

    Calzolari, Gabriele; Rossetti, Federico; Ault, Alexis K.; Lucci, Federico; Olivetti, Valerio; Nozaem, Reza

    2018-03-01

    The Kuh-e-Faghan strike-slip fault system (KFF), located to the northern edge of the Lut Block in central Iran, developed through a Neogene-Quaternary pulsed history of eastward fault propagation and fault-related exhumation. This system is a consequence of the residual stresses transmitted from the Arabia-Eurasia convergent plate boundary. Here we integrate structural and textural analysis with new and previously published apatite fission-track (AFT) and apatite (U-Th)/He (apatite He) results, chlorite thermomentry, and hematite (U-Th)/He data from hematite-coated brittle fault surfaces to constrain the timing of tectonic activity and refine patterns of late Miocene-Pliocene burial and exhumation associated with the propagation of the KFF. Twenty-nine hematite (U-Th)/He (hematite He) dates from three striated hematite coated slip surfaces from the KFF fault core and damage zone yield individual dates from 12-2 Ma. Petrographic analysis and chlorite thermometry of a polyphase, fossil fluid system in the KFF fault core document that fluid circulation and mineralization transitioned from a closed system characterized by pressure solution and calcite growth to an open system characterized by hot hydrothermal (T = 239 ± 10 °C) fluids and hematite formation. Hematite microtextures and grain size analysis reveal primary and secondary syntectonic hematite fabrics, no evidence of hematite comminution and similar hematite He closure temperatures ( 60-85 °C) in each sample. Integration of these results with thermal history modeling of AFT and apatite He data shows that KFF activity in the late Miocene is characterized by an early stage of fault nucleation, fluid circulation, hematite mineralization, and eastward propagation not associated with vertical movement that lasted from 12 to 7 Ma. Hematite He, AFT, and apatite He data track a second phase of fault system activity involving fault-related exhumation initiating at 7 Ma and continuing until present time. Our new data

  13. Reconstructing Holocene hematite and goethite variations in the Indus Canyon to trace changes in the Asian monsoon system

    Science.gov (United States)

    Koehler, Cornelia; Clift, Peter; Pressling, Nicola; Limmer, David; Giosan, Liviu; Tabrez, Ali

    2010-05-01

    In order to study Holocene Asian monsoon variations, we reconstructed changes in chemical weathering by examining sediments from the Indus Canyon. During the late Holocene, the Asian monsoon system had periods of high and low intensities that influenced the civilisations living in its realm. For example, the demise of the Harappan civilisation has been linked to a weakened monsoon system around 4 ka. The sediments in the Indus Canyon, which originate from the River Indus and its Himalayan tributaries, provide an ideal, natural environmental archive of the South Asian monsoon system. In order to investigate the alternation between arid and humid monsoonal climatic conditions, variations are traced using the magnetic minerals hematite and goethite, which form under distinct environmental conditions: goethite is stable under humid conditions, whereas hematite forms from the dehydration of goethite under arid conditions. The two minerals are characterised and quantified using environmental magnetic measurements, as well as diffuse reflectance spectrometry. Combining both approaches will enable us to reconstruct variations in chemical weathering over time. Furthermore, because this is governed by temperature and the availability of moisture, our weathering record will allow us to understand monsoon variability during the Holocene and test whether summer rain intensity has been decreasing in SW Asia since 8 ka. In addition, the multi-component analysis of colour reflectance spectra identifies different mineral components including hematite/goethite, clay mineral mixtures, calcite and organics. We will present our results from the multi-sensor core logger equipped with a Minolta spectrometer, measuring both magnetic susceptibility and the optical properties of the split sediment cores. Initial results indicate the presence of hematite and goethite in the sediment. There is an increasing hematite content up the cores, indicating an aridification trend during the Holocene

  14. Water-level altitudes 2014 and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction 1973-2013 in the Chicot and Evangeline aquifers, Houston-Galveston region, Texas

    Science.gov (United States)

    Kasmarek, Mark C.; Johnson, Michaela R.; Ramage, Jason K.

    2014-01-01

    Most of the land-surface subsidence in the Houston-Galveston region, Texas, has occurred as a direct result of groundwater withdrawals for municipal supply, commercial and industrial use, and irrigation that depressured and dewatered the Chicot and Evangeline aquifers, thereby causing compaction of the aquifer sediments, mostly in the fine-grained clay and silt layers. This report, prepared by the U.S. Geological Survey in cooperation with the Harris-Galveston Subsidence District, City of Houston, Fort Bend Subsidence District, Lone Star Groundwater Conservation District, and Brazoria County Groundwater Conservation District, is one in an annual series of reports depicting water-level altitudes and water-level changes in the Chicot, Evangeline, and Jasper aquifers and measured compaction of subsurface sediments in the Chicot and Evangeline aquifers in the Houston-Galveston region. The report contains maps depicting approximate 2014 water-level altitudes (represented by measurements made during December 2013–March 2014) for the Chicot, Evangeline, and Jasper aquifers; maps depicting 1-year (2013–14) water-level changes for each aquifer; maps depicting contoured 5-year (2009–14) water-level changes for each aquifer; maps depicting contoured long-term (1990–2014 and 1977–2014) water-level changes for the Chicot and Evangeline aquifers; a map depicting contoured long-term (2000–14) water-level changes for the Jasper aquifer; a map depicting locations of borehole-extensometer sites; and graphs depicting measured cumulative compaction of subsurface sediments at the borehole extensometers during 1973–2013. Tables listing the data used to construct each water-level map for each aquifer and the compaction graphs are included.

  15. Water-level altitudes 2015 and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction 1973-2014 in the Chicot and Evangeline aquifers, Houston-Galveston region, Texas

    Science.gov (United States)

    Kasmarek, Mark C.; Ramage, Jason K.; Houston, Natalie A.; Johnson, Michaela R.; Schmidt, Tiffany S.

    2015-01-01

    Most of the land-surface subsidence in the Houston-Galveston region, Texas, has occurred as a direct result of groundwater withdrawals for municipal supply, commercial and industrial use, and irrigation that depressured and dewatered the Chicot and Evangeline aquifers, thereby causing compaction of the aquifer sediments, mostly in the fine-grained silt and clay layers. This report, prepared by the U.S. Geological Survey in cooperation with the Harris-Galveston Subsidence District, City of Houston, Fort Bend Subsidence District, Lone Star Groundwater Conservation District, and Brazoria County Groundwater Conservation District, is one in an annual series of reports depicting water-level altitudes and water-level changes in the Chicot, Evangeline, and Jasper aquifers and measured cumulative compaction of subsurface sediments in the Chicot and Evangeline aquifers in the Houston-Galveston region. The report contains regional-scale maps depicting approximate 2015 water-level altitudes (represented by measurements made during December 2014–March 2015) for the Chicot, Evangeline, and Jasper aquifers; maps depicting 1-year (2014–15) water-level changes for each aquifer; maps depicting approximate contoured 5-year (2010–15) water-level changes for each aquifer; maps depicting approximate contoured long-term (1990–2015 and 1977–2015) water-level changes for the Chicot and Evangeline aquifers; a map depicting approximate contoured long-term (2000–15) water-level changes for the Jasper aquifer; a map depicting locations of borehole-extensometer sites; and graphs depicting measured cumulative compaction of subsurface sediments at the borehole extensometers during 1973–2014. Three tables listing the water-level data used to construct each water-level map for each aquifer and a table listing the measured cumulative compaction data for each extensometer site and graphs are included.

  16. Water-level altitudes 2013 and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction 1973--2012 in the Chicot and Evangeline aquifers, Houston-Galveston region, Texas

    Science.gov (United States)

    Kasmarek, Mark C.; Johnson, Michaela R.; Ramage, Jason K.

    2013-01-01

    Most of the subsidence in the Houston-Galveston region, Texas, has occurred as a direct result of groundwater withdrawals for municipal supply, commercial and industrial use, and irrigation that depressured and dewatered the Chicot and Evangeline aquifers, thereby causing compaction mostly in the clay and silt layers of the aquifer sediments. This report, prepared by the U.S. Geological Survey in cooperation with the Harris-Galveston Subsidence District, City of Houston, Fort Bend Subsidence District, Lone Star Groundwater Conservation District, and Brazoria County Groundwater Conservation District, is one in an annual series of reports depicting water-level altitudes and water-level changes in the Chicot, Evangeline, and Jasper aquifers and measured compaction of subsurface sediments in the Chicot and Evangeline aquifers in the Houston-Galveston region. The report contains maps depicting approximate water-level altitudes for 2013 (represented by measurements made during December 2012-February 2013) for the Chicot, Evangeline, and Jasper aquifers; maps depicting 1-year (2012-13) water-level changes for each aquifer; maps depicting 5-year (2008--13) water-level changes for each aquifer; maps depicting long-term (1990-2013 and 1977-2013) water-level changes for the Chicot and Evangeline aquifers; a map depicting long-term (2000-13) water-level changes for the Jasper aquifer; a map depicting locations of borehole-extensometer sites; and graphs depicting measured compaction of subsurface sediments at the extensometers during 1973-2012. Tables listing the data used to construct each water-level map for each aquifer and the compaction graphs are included.

  17. Water-level altitudes 2012 and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction 1973-2011 in the Chicot and Evangeline aquifers, Houston-Galveston region, Texas

    Science.gov (United States)

    Kasmarek, Mark C.; Johnson, Michaela R.; Ramage, Jason K.

    2012-01-01

    Most of the subsidence in the Houston–Galveston region, Texas, has occurred as a direct result of groundwater withdrawals for municipal supply, commercial and industrial use, and irrigation that depressured and dewatered the Chicot and Evangeline aquifers and caused compaction of the clay layers of the aquifer sediments. This report—prepared by the U.S. Geological Survey in cooperation with the Harris– Galveston Subsidence District, City of Houston, Fort Bend Subsidence District, Lone Star Groundwater Conservation District, and Brazoria County Groundwater Conservation District—is one in an annual series of reports depicting water-level altitudes and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction in the Chicot and Evangeline aquifers in the Houston–Galveston region. The report contains maps showing approximate water-level altitudes for 2012 (calculated from measurements of water levels in wells made during December 2011–February 2012) for the Chicot, Evangeline, and Jasper aquifers; maps showing 1-year (2011–12) water-level-altitude changes for each aquifer; maps showing 5-year (2007–12) water-levelaltitude changes for each aquifer; maps showing long-term (1990–2012 and 1977–2012) water-level-altitude changes for the Chicot and Evangeline aquifers; a map showing long-term (2000–12) water-level-altitude change for the Jasper aquifer; a map showing locations of borehole extensometer sites; and graphs showing measured compaction of subsurface sediments at the extensometers from 1973 (or later) through 2011. Tables listing the data that were used to construct each water-level map for each aquifer and the cumulative compaction graphs are included.

  18. Estimated rates of groundwater recharge to the Chicot, Evangeline and Jasper aquifers by using environmental tracers in Montgomery and adjacent counties, Texas, 2008 and 2011

    Science.gov (United States)

    Oden, Timothy D.; Truini, Margot

    2013-01-01

    Montgomery County is in the northern part of the Houston, Texas, metropolitan area, the fourth most populous metropolitan area in the United States. As populations have increased since the 1980s, groundwater has become an important resource for public-water supply and industry in the rapidly growing area of Montgomery County. Groundwater availability from the Gulf Coast aquifer system is a primary concern for water managers and community planners in Montgomery County and requires a better understanding of the rate of recharge to the system. The Gulf Coast aquifer system in Montgomery County consists of the Chicot, Evangeline, and Jasper aquifers, the Burkeville confining unit, and underlying Catahoula confining system. The individual sand and clay sequences of the aquifers composing the Gulf Coast aquifer system are not laterally or vertically continuous on a regional scale; however, on a local scale, individual sand and clay lenses can extend over several miles. The U.S. Geological Survey, in cooperation with the Lone Star Groundwater Conservation District, collected groundwater-quality samples from selected wells within or near Montgomery County in 2008 and analyzed these samples for concentrations of chlorofluorocarbons (CFCs), sulfur hexafluoride (SF6), tritium (3H), helium-3/tritium (3He/3H), helium-4 (4He), and dissolved gases (DG) that include argon, carbon dioxide, methane, nitrogen and oxygen. Groundwater ages, or apparent age, representing residence times since time of recharge, were determined by using the assumption of a piston-flow transport model. Most of the environmental tracer data indicated the groundwater was recharged prior to the 1950s, limiting the usefulness of CFCs, SF6, and 3H concentrations as tracers. In many cases, no tracer was usable at a well for the purpose of estimating an apparent age. Wells not usable for estimating an apparent age were resampled in 2011 and analyzed for concentrations of major ions and carbon-14 (14C). At six of

  19. RECOVERY OF IRON FROM LOW-GRADE HEMATITE ORE USING COAL-BASED DIRECT REDUCTION FOLLOWED BY MAGNETIC SEPARATION

    Directory of Open Access Journals (Sweden)

    N. Alavifard

    2016-09-01

    Full Text Available In the present work, iron recovery from a low-grade hematite ore (containing less than 40% iron, which is not applicable in common methods of ironmaking, was studied. Non-coking coal was used as reducing agent. Reduction experiments were performed under various coal to hematite ratios and temperatures. Reduction degree was calculated using the gravimetric method. Reduced samples were subjected to magnetic separation followed by X-ray diffraction analysis. Total iron content, degree of metallization and recovery efficiency in magnetic part were determined by quantitative chemical analysis, which were obtained about 82%, 95% and 64% respectively under optimal conditions. CaO as an additive improved ore reducibility and separation efficiency. The microstructure of reduced samples and final products were analyzed by scanning electron microscopy. Final product with a high degree of metallization can be used in steel making furnaces and charging of blast furnaces which can improve production efficiency and decrease coke usage.

  20. (U-Th)/He thermochronometry reveals Pleistocene punctuated deformation and synkinematic hematite mineralization in the Mecca Hills, southernmost San Andreas Fault zone

    Science.gov (United States)

    Moser, Amy C.; Evans, James P.; Ault, Alexis K.; Janecke, Susanne U.; Bradbury, Kelly K.

    2017-10-01

    The timing, tempo, and processes of punctuated deformation in strike-slip fault systems are challenging to resolve in the rock record. Faults in the Mecca Hills, adjacent to the southernmost San Andreas Fault, California, accommodate active deformation and exhumation in the Plio-Pleistocene sedimentary rocks and underlying crystalline basement. We document the spatiotemporal patterns of San Andreas Fault-related deformation as recorded in crystalline basement rocks of the Mecca Hills using fault microstructural observations, geochemical data, and hematite (n = 24) and apatite (n = 44) (U-Th)/He (hematite He, apatite He) thermochronometry data. Reproducible mean hematite He dates from minor hematite-coated fault surfaces in the Painted Canyon Fault damage zone range from ∼0.7-0.4 Ma and are younger than ∼1.2 Ma apatite He dates from adjacent crystalline basement host rock. These data reveal concomitant Pleistocene pulses of fault slip, fluid flow, and synkinematic hematite mineralization. Hematite textures, crystal morphology, and hematite He data patterns imply some damage zone deformation occurred via cyclic crack-seal and creep processes. Apatite He data from crystalline basement define distinct date-eU patterns and indicate cooling across discrete fault blocks in the Mecca Hills. Uniform ∼1.2 Ma apatite He dates regardless of eU are located exclusively between the Painted Canyon and Platform faults. Outside of this fault block, samples yield individual apatite He dates from ∼30-1 Ma that define a positive apatite He date-eU correlation. These patterns reveal focused exhumation away from the main trace of the San Andreas Fault at ∼1.2 Ma. Low-temperature thermochronometry of fault-related rocks provides an unprecedented window into the 105-106-yr record of San Andreas Fault-related deformation in the Mecca Hills and documents hematite deformation mechanisms that may be operative in other strike-slip faults world-wide.

  1. Cosmogenic 3He in hematite and goethite from Brazilian "canga" duricrust demonstrates the extreme stability of these surfaces

    Science.gov (United States)

    Shuster, David L.; Farley, Kenneth A.; Vasconcelos, Paulo M.; Balco, Greg; Monteiro, Hevelyn S.; Waltenberg, Kathryn; Stone, John O.

    2012-05-01

    Helium isotopes were measured in hematite and goethite samples from several lateritiric duricrusts (canga) developed on banded iron formations. These samples uniformly have high 3He concentrations which must arise from long periods of cosmic ray exposure. From coexisting phases from the Quadrilátero Ferrífero in east central Brazil, we determined the ratio of cosmogenic 3He in hematite to that of 21Ne in quartz to be 3.96 ± 0.19. Combined with best current estimates of the 21Ne production rate in quartz, this ratio implies a sea-level high latitude (SLHL) 3He production rate in hematite of 68.1 ± 8.1 atoms/g/yr; from the chemical composition we estimate the 3He production rate in goethite to be ~ 5% higher. We use these production rate estimates to interpret 3He concentrations measured in goethite and hematite from a ~ 10 m depth profile collected from a surface canga in Carajás, in the Amazon basin of Brazil. We find that the Carajás canga has experienced a very low rate of surface erosion (~ 0.16-0.54 m/Myr) over at least the last few millions of years. This iron-rich canga surface is remarkably resistant to erosion despite its location in a wet tropical environment. Details of the depth profile suggest that despite its stability, the canga has also been internally dynamic (translocation of material; solution and reprecipitation) over million-year timescales.

  2. Observation of multiphase magnetic state of hematite crystal during Morin transition by the method of section topography of synchrotron radiation

    International Nuclear Information System (INIS)

    Shchetinkin, S.A.; Kvardakov, V.V.; Viler, Eh.; Barushel', Zh.; Shlenker, M.

    2005-01-01

    The boundaries between weak ferromagnetic and antiferromagnetic phases in hematite crystals during Morin transition are detected by the section topography method by synchrotron radiation. It is shown that these boundaries are parallel to (111) surface hence magnetic phases during Morin transition separate the crystal by layers. Change of layer depth in dependence on temperature and magnetic field, and interaction interphase boundaries with crystal defects are observed [ru

  3. Deposition of hematite particles on alumina seal faceplates of nuclear reactor coolant pumps: Laboratory experiments and industrial feedback

    OpenAIRE

    Lefèvre, Grégory; Živković, Ljiljana S.; Jaubertie, Anne

    2012-01-01

    In the primary circuit of pressurized water reactors (PWR), the dynamic sealing system in reactor coolant pumps is ensured by mechanical seals whose ceramic parts are in contact with the cooling solution. During the stretch-out phase in reactor operation, characterized by low boric acid concentration, the leak-off flow has been observed to abnormally evolve in industrial plants. The deposition of hematite particles, originating from corrosion, on alumina seals of coolant pumps is suspec...

  4. The effects of cerium doping on the size, morphology, and optical properties of α-hematite nanoparticles for ultraviolet filtration

    Energy Technology Data Exchange (ETDEWEB)

    Cardillo, Dean [Institute for Superconducting and Electronic Materials, AIIM Facility, University of Wollongong Innovation Campus, Squires Way, North Wollongong, NSW 2500 (Australia); Konstantinov, Konstantin, E-mail: konstan@uow.edu.au [Institute for Superconducting and Electronic Materials, AIIM Facility, University of Wollongong Innovation Campus, Squires Way, North Wollongong, NSW 2500 (Australia); Devers, Thierry [Centre de Recherche sur la Matière Divisée, Institut de Physique, site de Chartres, Université d’Orléans (France)

    2013-11-15

    Highlights: • Possible application of cerium-doped α-hematite as ultraviolet filter. • Nanoparticles obtained through co-precipitation technique using various cerium doping levels followed by annealing. • Comprehensive materials characterisation utilizing XRD, DSC/TGA, STEM, UV–vis spectroscopy. • Increasing cerium content reduces particle sizing and alters morphology. • Solubility of cerium in hematite seen between 5 and 10% doping, 10% cerium doping greatly enhances attenuation in ultraviolet region and increases optical bandgap. - Abstract: Metal oxide nanoparticles have potential use in energy storage, electrode materials, as catalysts and in the emerging field of nanomedicine. Being able to accurately tailor the desirable properties of these nanoceramic materials, such as particle size, morphology and optical bandgap (E{sub g}) is integral in the feasibility of their use. In this study we investigate the altering of both the structure and physical properties through the doping of hematite (α-Fe{sub 2}O{sub 3}) nanocrystals with cerium at a range of concentrations, synthesised using a one-pot co-precipitation method. This extremely simple synthesis followed by thermal treatment results in stable Fe{sub 2−x}Ce{sub x}O{sub y} nanoceramics resulting from the burning of any unreacted precursors and transformation of goethite-cerium doped nanoparticle intermediate. The inclusion of Ce into the crystal lattice of these α-Fe{sub 2}O{sub 3} nanoparticles causes a significantly large reduction in mean crystalline size and alteration in particle morphology with increasing cerium content. Finally we report an increase optical semiconductor bandgap, along with a substantial increase in the ultraviolet attenuation found for a 10% Ce-doping concentration which shows the potential application of cerium-doped hematite nanocrystals to be used as a pigmented ultraviolet filter for cosmetic products.

  5. A Density Functional Theory Study of the Adsorption of Benzene on Hematite (α-Fe2O3 Surfaces

    Directory of Open Access Journals (Sweden)

    Nelson Y. Dzade

    2014-02-01

    Full Text Available The reactivity of mineral surfaces in the fundamental processes of adsorption, dissolution or growth, and electron transfer is directly tied to their atomic structure. However, unraveling the relationship between the atomic surface structure and other physical and chemical properties of complex metal oxides is challenging due to the mixed ionic and covalent bonding that can occur in these minerals. Nonetheless, with the rapid increase in computer processing speed and memory, computer simulations using different theoretical techniques can now probe the nature of matter at both the atomic and sub-atomic levels and are rapidly becoming an effective and quantitatively accurate method for successfully predicting structures, properties and processes occurring at mineral surfaces. In this study, we have used Density Functional Theory calculations to study the adsorption of benzene on hematite (α-Fe2O3 surfaces. The strong electron correlation effects of the Fe 3d-electrons in α-Fe2O3 were described by a Hubbard-type on-site Coulomb repulsion (the DFT+U approach, which was found to provide an accurate description of the electronic and magnetic properties of hematite. For the adsorption of benzene on the hematite surfaces, we show that the adsorption geometries parallel to the surface are energetically more stable than the vertical ones. The benzene molecule interacts with the hematite surfaces through π-bonding in the parallel adsorption geometries and through weak hydrogen bonds in the vertical geometries. Van der Waals interactions are found to play a significant role in stabilizing the absorbed benzene molecule. Analyses of the electronic structures reveal that upon benzene adsorption, the conduction band edge of the surface atoms is shifted towards the valence bands, thereby considerably reducing the band gap and the magnetic moments of the surface Fe atoms.

  6. NaF-assisted hydrothermal synthesis of Ti-doped hematite nanocubes with enhanced photoelectrochemical activity for water splitting

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Chong; Zhu, Zezhou; Wang, Sibo; Hou, Yidong, E-mail: ydhou@fzu.edu.cn

    2015-12-30

    Graphical abstract: An enhanced photoelectrochemical activity for water splitting was achieved over porous Ti-doped α-Fe{sub 2}O{sub 3} nanocubes. - Highlights: . • Ti-doped hematite nanocubes were successfully prepared by NaF-assisted hydrothermal deposition and subsequent annealing. • Ti-doped α-Fe{sub 2}O{sub 3} nanocubes showed an enhanced PEC activity with an IPCE of 25.2% at 340 nm at 1.23 V vs. RHE. • The enhanced activity of Ti-doped hematite nanocubes can be ascribed to high surface area and fast charge transportation. - Abstract: Ti-doped α-Fe{sub 2}O{sub 3} nanocubes on FTO substrate was prepared by hydrothermal deposition β-FeOOH onto FTO glass with a solution of FeCl{sub 3}, TiOCl{sub 2} and NaF, followed by an appropriate annealing. In comparison to Ti-doped α-Fe{sub 2}O{sub 3} nanorods Ti-doped α-Fe{sub 2}O{sub 3} nanocubes showed an enhanced photoelectrochemical activity for water splitting, with a remarkable IPCE of 25.2% at 340 nm at the potential of 1.23 V vs. RHE. The hematite films were studied in detail by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, UV–vis absorption spectroscopy and electrochemical impedance spectroscopy. On the basis of the obtained results, the improved performance of Ti-doped α-Fe{sub 2}O{sub 3} nanocubes can be ascribed to the porous structure, good electrical conductivity and fast charge transportation of hematite.

  7. Compositional Models of Hematite-Rich Spherules (Blueberries) at Meridiani Planum, Mars and Constraints on Their Formation

    Science.gov (United States)

    Schneider, A.; Mittlefehldt, D.

    2006-10-01

    The Mars Exploration Rover Opportunity discovered hematite-rich spherules (``blueberries'') believed to be diagenetic concretions formed in the bedrock in stagnant or slow-moving groundwater. These spherules likely precipitated from solution, but their origins are poorly understood. Three formation mechanisms are possible: inclusive, replacive and displacive. The first would result in a distinct spherule composition compared to the other two. We propose that chemical clues may help to constrain the nature of blueberry formation. We used Alpha Particle X-ray Spectrometer data for undisturbed soils that were blueberry-free and with visible blueberries at the surface in Microscopic Imager images. We made plots of the elements versus iron for the spherule-rich soils and compared them to a mixing line representative of a pure hematite end member spherule (called ``the zero model''). This modeled the replacive formation mechanism, in which pure hematite would replace all of the original material. If the spherules grew inclusively, chemical data should reflect a compositional component of the rock grains included during formation. Four models were developed to test for possible compositions of a rock component. These models could not easily explain the APXS data and thus demonstrate that the most plausible rock compositions are not components of blueberries.

  8. Confinement and surface effects on the physical properties of rhombohedral-shape hematite (α-Fe_2O_3) nanocrystals

    International Nuclear Information System (INIS)

    Luna, Carlos; Cuan-Guerra, Aída D.; Barriga-Castro, Enrique D.; Núñez, Nuria O.; Mendoza-Reséndez, Raquel

    2016-01-01

    Highlights: • Uniform rhombohedral hematite nanocrystals (RHNCs) have been obtained. • A detailed formation mechanism of these HNCS has been proposed. • Phonon confinement effects were revealed in the RHNCS vibrational bands. • Quantum confinement effects on the optical and electronic properties were found. - Abstract: Morphological, microstructural and vibrational properties of hematite (α-Fe_2O_3) nanocrystals with a rhombohedral shape and rounded edges, obtained by forced hydrolysis of iron(III) solutions under a fast nucleation, have been investigated in detail as a function of aging time. These studies allowed us to propose a detailed formation mechanism and revealed that these nanocrystals are composed of four {104} side facets, two {110} faces at the edges of the long diagonal of the nanocrystals and two {−441} facets as the top and bottom faces. Also, the presence of nanoscopic pores and fissures was evidenced. The vibrational bands of such nanocrystals were shifted to lower frequencies in comparison with bulk hematite ones as the nanocrystal size was reduced due to phonon confinement effects. Also, the indirect and direct transition band gaps displayed interesting dependences on the aging time arising from quantum confinement and surface effects

  9. Occlusion of chromophore oxides by Sol-Gel methods: Application to the synthesis of hematite-silica red pigments

    Directory of Open Access Journals (Sweden)

    Vicent, J. B.

    2000-02-01

    Full Text Available Heteromorphic pigments present the chromophore particle occluded in an encapsulating matrix which is thermally stable and insoluble in glazes. The occluded chromophore compound is also insoluble in the host matrix. In this work the mechanisms of formation of this type of pigments are analyzed and the occlusion of hematite into silica matrix is discussed. The formation of this hematite-silica red pigment follows a sintering-coarsening mechanism, and, consequently, the control of both hematite particles nucleation and their crystal growth results to be decisive to obtain a good coloring effectiveness.

    En los pigmentos heteromórficos la partícula de cromóforo es ocluida en una matriz encapsuladora estable tanto termicamente como frente a los vidriados. El compuesto cromóforo ocluido y la matriz no coloreada son insolubles. En este trabajo se analiza los diferentes mecanismos de formación de estos pigmentos heteromórficos y se estudia la oclusión de hematita en sílice mediante métodos sol-gel acuoso. El pigmento sigue un mecanismo de sinterización-crecimiento cristalino por lo que es muy importante controlar el momento de nucleación y la velocidad de crecimiento de las partículas de hematita en el seno de la matriz.

  10. Aggregation Kinetics of Hematite Particles in the Presence of Outer Membrane Cytochrome OmcA of Shewanella oneidenesis MR-1

    Energy Technology Data Exchange (ETDEWEB)

    Sheng, Anxu [Peking Univ., Beijing (China). College of Environmental Sciences and Engineering; Liu, Feng [Peking Univ., Beijing (China). College of Environmental Sciences and Engineering; Shi, Liang [China Univ. of Geoscience in Wuhan, Hubei (China). Dept. of Biological Sciences and Technology; Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Liu, Juan [Peking Univ., Beijing (China). College of Environmental Sciences and Engineering

    2016-09-20

    The aggregation behavior of 9, 36, and 112 nm hematite particles was studied in the presence of OmcA, a bacterial extracellular protein, in aqueous dispersions at pH 5.7 through time-resolved dynamic light scattering, electrophoretic mobility, and circular dichroism spectra, respectively. At low salt concentration, the attachment efficiencies of hematite particles in all sizes first increased, then decreased, and finally remained stable with the increase of OmcA concentration, indicating the dominant interparticle interaction changed along with the increase in the protein-to-particle ratio. Nevertheless, at high salt concentration, the attachment efficiencies of all hematite samples gradually decreased with increasing OmcA concentration, which can be attributed to increasing steric force. Additionally, the aggregation behavior of OmcA-hematite conjugates was more correlated to total particle-surface area than primary particle size. It was further established that OmcA could stabilize hematite nanoparticles more efficiently than bovine serum albumin (BSA), a model plasma protein, due to the higher affinity of OmcA to hematite surface. This study highlighted the effects of particle properties, solution conditions, and protein properties on the complicated aggregation behavior of protein-nanoparticle conjugates in aqueous environments.

  11. Clusters and holes: Exchange networks in hematite-ilmenite solid solutions

    Science.gov (United States)

    Fabian, K.; McEnroe, S. A.; Robinson, P.

    2009-04-01

    Holes and clusters of exchange networks dominate the low-temperature, metastable phase diagram of the system (1 - x)Fe2O3 xF eTiO3 (Ilmx ). By our measurements we have probed and extended the phase diagram of Ishikawa et al. (1985) in the light of magnetic influences of the random exchange links, which originate either by replacing random pairs of Fe2+ and Ti4+ ions in the ordered ilmenite lattice by two Fe3+ions (ordered Ilmx phase), or by randomly replacing two Fe3+ ions in the hematite lattice by a pair of Fe2+ and Ti4+ ions (disordered Ilmx phase). Now a large dataset is available from these measurements, and we propose several new ideas to interpret the sometimes unexpected results. By refining a method of Ishikawa (1967), we analyze the PM' region of the phase diagram in terms of a mean field theory of interacting clusters. This allows to determine cluster sizes and interaction field distribution by inverting hysteresis measurements of Ilm92 and Ilm97. To understand the relation between ordered and disordered phases we design a mean field theory to determine Neel and Curie temperatures of both. An especially interesting finding is that the experimentally observed intersection of PM-PM' crossover with the AF phase boundary close to Ilm97 can be explained by analyzing average exchange interaction strengths.

  12. Adatom Fe(III on the hematite surface: Observation of a key reactive surface species

    Directory of Open Access Journals (Sweden)

    Rosso Kevin M

    2004-06-01

    Full Text Available The reactivity of a mineral surface is determined by the variety and population of different types of surface sites (e.g., step, kink, adatom, and defect sites. The concept of "adsorbed nutrient" has been built into crystal growth theories, and many other studies of mineral surface reactivity appeal to ill-defined "active sites." Despite their theoretical importance, there has been little direct experimental or analytical investigation of the structure and properties of such species. Here, we use ex-situ and in-situ scanning tunneling microcopy (STM combined with calculated images based on a resonant tunneling model to show that observed nonperiodic protrusions and depressions on the hematite (001 surface can be explained as Fe in an adsorbed or adatom state occupying sites different from those that result from simple termination of the bulk mineral. The number of such sites varies with sample preparation history, consistent with their removal from the surface in low pH solutions.

  13. Influence of Lanthanum Doping on the Structural and Optical Properties of Hematite Nanopowders

    Science.gov (United States)

    Justus, J. Sharmila; Dharma Roy, S. Dawn; Raj, A. Moses Ezhil

    2016-10-01

    Rare-earth elements are an attractive class of dopant elements, as they give easily trivalent cations that possibly altering the structure and other properties of the parent nanoparticles and creating multifunctional materials because of their f-electronic configurations. Herein, experimental evidence has been given for a better understanding of the factors that dictate the interactions of La doping on the structure and optical properties of iron oxide nanoparticles. For that, lanthanum doped hematite (α-Fe2O3) nanoparticles were prepared by a facile solution method using iron (III) chloride (FeCl3) as starting precursor and sodium hydroxide (NaOH) as reducing agent without templates at low temperature. As-prepared powders were subsequently calcined in air for 3 hr at 800 °C. Xray diffraction (XRD) technique was used to study the nanocrystal formation of α-Fe2O3 and Fourier Transform Raman (FT-Raman) spectral information identified the chemical bond structure of the nanoparticles. Morphology study of the nanoparticles was identified using Scanning Electron Microscope (SEM) and the incorporated La content was recognized from the Energy Dispersive X-ray Spectroscopy (EDS) analysis. The optical absorption spectrum was recorded in the wavelength range of 200-2000 nm and the optical parameters such as absorption coefficient and optical band gap energy of pure and doped Fe2O3 nanoparticles were determined. Obtained results are interpreted by considering the impregnation of trivalent La cations that replaced Fe cations of the host structure.

  14. Spectroscopic Confirmation of Uranium (VI)-Carbonato Adsorption Complexes on Hematite

    International Nuclear Information System (INIS)

    Bargar, John R

    1999-01-01

    Evaluating societal risks posed by uranium contamination from waste management facilities, mining sites, and heavy industry requires knowledge about uranium transport in groundwater, often the most significant pathway of exposure to humans. It has been proposed that uranium mobility in aquifers may be controlled by adsorption of U(VI)-carbonato complexes on oxide minerals. The existence of such complexes has not been demonstrated, and little is known about their compositions and reaction stoichiometries. We have used Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) and Extended X-ray Absorption Fine Structure (EXAFS) spectroscopies to probe the existence, structures, and compositions of FeO surface -U(VI)-carbonato complexes on hematite throughout the pH range of uranyl uptake under conditions relevant to aquifers. U(VI)-carbonato complexes were found to be the predominant adsorbed U(VI) species at all pH values examined, a much wider pH range than previously postulated based on analogy to aqueous U(VI)-carbonato complexes, which are trace constituents at pH < 6. This result indicates the inadequacy of the common modeling assumption that the compositions and predominance of adsorbed species can be inferred from aqueous species. By extension, adsorbed carbonato complexes may be of major importance to the groundwater transport of similar actinide contaminants such as neptunium and plutonium

  15. Spectroscopic confirmation of uranium(VI)-carbonato adsorption complexes on hematite

    Science.gov (United States)

    Bargar, John R.; Reitmeyer, Rebecca; Davis, James A.

    1999-01-01

    Evaluating societal risks posed by uranium contamination from waste management facilities, mining sites, and heavy industry requires knowledge about uranium transport in groundwater, often the most significant pathway of exposure to humans. It has been proposed that uranium mobility in aquifers may be controlled by adsorption of U(VI)−carbonato complexes on oxide minerals. The existence of such complexes has not been demonstrated, and little is known about their compositions and reaction stoichiometries. We have used attenuated total reflectance Fourier transform infrared (ATR-FTIR) and extended X-ray absorption fine structure (EXAFS) spectroscopies to probe the existence, structures, and compositions of ≡FeOsurface−U(VI)−carbonato complexes on hematite throughout the pH range of uranyl uptake under conditions relevant to aquifers. U(VI)−carbonato complexes were found to be the predominant adsorbed U(VI) species at all pH values examined, a much wider pH range than previously postulated based on analogy to aqueous U(VI)−carbonato complexes, which are trace constituents at pH carbonato complexes may be of major importance to the groundwater transport of similar actinide contaminants such as neptunium and plutonium.

  16. Influence of hematite nanorods on the mechanical properties of epoxy resin

    Directory of Open Access Journals (Sweden)

    Bogdanović Gordana

    2017-01-01

    Full Text Available The mechanical properties of nanocomposites obtained by incorporation of fairly uniform hematite nanorods (α-Fe2O3 NRs into epoxy resin were studied as a function of the content of the inorganic phase. A thorough microstructural characterization of the α-Fe2O3 NRs and the nanocomposites was performed using transmission electron microscopy (TEM and atomic force microscopy (AFM. The TEM measurements revealed rod-like morphology of the nanofiller with a uniform size distribution (8.5 nm×170 nm, diameter×length. High-magnification TEM and AFM measurements indicated agglomeration of α-Fe2O3 NRs embedded in the epoxy resin. Stress at break, strain at break, elastic modulus and tensile toughness of the nanocomposites were compared with the data obtained for pure epoxy resin. Significant influence of nanofiller on the mechanical properties of epoxy resin, as well as on the glass transition temperature, could be noticed for samples with low contents of the inorganic phase (up to 1 wt. %. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 45020

  17. Prediction of the effects of size and morphology on the structure of water around hematite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Spagnoli, D.; Gilbert, B.; Waychunas, G.A.; Banfield, J. F.

    2009-05-15

    Compared with macroscopic surfaces, the structure of water around nanoparticles is difficult to probe directly. We used molecular dynamics simulations to investigate the effects of particle size and morphology on the time-averaged structure and the dynamics of water molecules around two sizes of hematite ({alpha}-Fe{sub 2}O{sub 3}) nanoparticles. Interrogation of the simulations via atomic density maps, radial distribution functions and bound water residence times provide insight into the relationships between particle size and morphology and the behavior of interfacial water. Both 1.6 and 2.7 nm particles are predicted to cause the formation of ordered water regions close to the nanoparticle surface, but the extent of localization and ordering, the connectivity between regions of bound water, and the rates of molecular exchange between inner and outer regions are all affected by particle size and morphology. These findings are anticipated to be relevant to understanding the rates of interfacial processes involving water exchange and the transport of aqueous ions to surface sites.

  18. Production of low-silicon molten iron from high-silica hematite using biochar

    Institute of Scientific and Technical Information of China (English)

    Hui-qing Tang∗; Xiu-feng Fu; Yan-qi Qin; Shi-yu Zhao; Qing-guo Xue

    2017-01-01

    A new method of utilizing high-silica hematite to produce low-silicon molten iron was proposed.In this method, FASTMELT, which comprised direct reduction and melt separation processes, was applied, with highly reactive biochar as the reductant in the direct reduction stage.The proposed method was ex-perimentally investigated and the results show that the method is feasible.In the direct reduction stage, ore-char briquette could achieve a metallization rate of 84%-88% and residual carbon of 0.27-0.89 mass% at temperature of 1 373 K, biochar mixing ratio of 0.8-0.9, and reduction time of 15 min.Some silica particles remained embedded in the iron phase after the reduction.In the melting separation stage, molten iron with a carbon content of 0.02-0.03 mass% and silicon content of 0.02-0.18 mass% could be obtained from the metallic briquettes under the above-mentioned conditions; the iron recovery rate was 83%-91% and impurities in the obtained metal were negligible.

  19. Quantitative Investigation of Roasting-magnetic Separation for Hematite Oolitic-ores: Mechanisms and Industrial Application

    Directory of Open Access Journals (Sweden)

    Peng Tiefeng

    2017-12-01

    Full Text Available Natural high-quality iron can be directly applied to pyro-metallurgy process, however, the availability of these ores has become less and less due to exploitation. This research reports a systematic approach using reduction roasting and magnetic separation for oolitic iron ores from west Hubei Province. Firstly, a mineralogical study was performed and it was shown that the oolitic particles were mainly composed of hematite, with some silicon-quartz inside the oolitic particle. Then, the roasting temperature was examined and shown to have significant influence on both Fe recovery and the Fe content of the concentrate. Also the Fe content gradually increased as the temperature increased from 700 to 850 °C. The most important aspects are the quantitative investigation of change of mineral phases, and reduction area (with ratio during the reduction roasting process. The results showed that Fe2O3 decreased with temperature, and Fe3O4 (magnetite increased considerably from 600 to 800 °C. The reductive reaction was found to occur from the outside in, the original oolitic structure and embedding relationship among the minerals did not change after roasting. Finally, 5% surrounding rock was added to mimic real industrial iron beneficiation. This study could provides useful insight and practical support for the utilization of such iron ores.

  20. Optimization of flotation variables for the recovery of hematite particles from BHQ ore

    Science.gov (United States)

    Rath, Swagat S.; Sahoo, Hrushikesh; Das, B.

    2013-07-01

    The technology for beneficiation of banded iron ores containing low iron value is a challenging task due to increasing demand of quality iron ore in India. A flotation process has been developed to treat one such ore, namely banded hematite quartzite (BHQ) containing 41.8wt% Fe and 41.5wt% SiO2, by using oleic acid, methyl isobutyl carbinol (MIBC), and sodium silicate as the collector, frother, and dispersant, respectively. The relative effects of these variables have been evaluated in half-normal plots and Pareto charts using central composite rotatable design. A quadratic response model has been developed for both Fe grade and recovery and optimized within the experimental range. The optimum reagent dosages are found to be as follows: collector concentration of 243.58 g/t, dispersant concentration of 195.67 g/t, pH 8.69, and conditioning time of 4.8 min to achieve the maximum Fe grade of 64.25% with 67.33% recovery. The predictions of the model with regard to iron grade and recovery are in good agreement with the experimental results.

  1. Facet-controlled synthesis of polyhedral hematite/carbon composites with enhanced photoactivity

    Science.gov (United States)

    Hu, Xiaoyi; Han, Sancan; Zhu, Yufang

    2018-06-01

    Much effort has been made to develop the semiconductor photocatalysis, but it is still challenging to fabricate low-cost and high-activity photocatalysts. In this study, Hematite (α-Fe2O3) with three kinds of morphologies including dodecahedron, tetrakaidecahedron and hexagonal nanoplates have been synthesized without any organic reagents. The photocatalytic performance reveals that the dodecahedron with exposed {1 0 1} facets is superior to the hexagonal nanoplates with predominant exposure of {0 0 1} facets in the case of similar BET surface area. For further enhancement of photocatalytic activity, carbon layer was coated on dodecahedral α-Fe2O3 through the self-polymerization of dopamine and following pyrolysis at 400 °C under Ar flow. Compared with the pristine dodecahedral α-Fe2O3, the α-Fe2O3/C composites exhibit stronger visible absorption, lower photoexcited electron-hole pairs recombination rate and better photodegradation activity. The photocatalytic performance showed the degradation rate of α-Fe2O3-D/4.5C is nearly 6 times higher than pristine α-Fe2O3, which have great potential for photocatalysis applications.

  2. Evaluation of the bleaching flux in clays containing hematite and different clay minerals

    International Nuclear Information System (INIS)

    Silva Junior, E.M.; Lusa, T.; Silva, T.M.; Medeiros, B.B.; Santos, G.R. dos; Morelli, M.R.

    2016-01-01

    Previous studies have shown that the addition of a synthetic flux in a clay mineral constituted by illite phase in the presence of iron oxide with the hematite, promotes color change of the firing products, making the reddish color firing into whiteness. This flow is constituted of a vitreous phase of the silicates family obtained by fusion/solidification of oxides and carbonates. Thus, the objective of this work was that of studying the interaction of the iron element in the final color mechanism of the different types of mineral crystal phase of the clays. In order to study the phenomenon, we obtained different compositions between the select clays and the synthetic flow, and characterization using X-ray diffraction (XRD) and visual analysis. The results showed that the action of the synthetic flow as a modifying agent for color depends on the mineral crystal phase of the clays. The color firing modification does not occur in the clays content high levels of kaolinite mineral phase. (author)

  3. Relation between electric properties and water saturation for hematitic sandstone with frequency

    Directory of Open Access Journals (Sweden)

    M. M. Gomaa

    2008-06-01

    Full Text Available This paper focuses on the effect of water saturation on A. C. electrical conductivity and dielectric constant of fully and partially saturated hematitic sandstone sample (Aswan area, Egypt. The saturation of the sample was changed from partial to full saturation. Complex resistivity measurements at room temperature (~16°C, were performed in the frequency range from 0.1 Hz to 100 KHz. Experimental electrical spectra indicate, generally, that the electrical conductivity and dielectric constant vary strongly with water saturations and frequency. The low frequency electrical conductivity and dielectric constant are mainly controlled by surface conduction and polarization of the electrical double layer. The behaviour of the electrical conductivity and dielectric constant, with increasing water content, were argued to the orientational polarization of bound water for very low saturations, displacement of the excess surface charges for relatively low saturations, and free exchange of excess ions in double layer with the bulk electrolyte and generation of transient diffusion potentials which lag behind the applied field for high saturations.

  4. Hematite Thin Films with Various Nanoscopic Morphologies Through Control of Self-Assembly Structures

    Science.gov (United States)

    Liu, Jingling; Kim, Yong-Tae; Kwon, Young-Uk

    2015-05-01

    Hematite (α-Fe2O3) thin films with various nanostructures were synthesized through self-assembly between iron oxide hydroxide particles, generated by hydrolysis and condensation of Fe(NO3)3 · 6H2O, and a Pluronic triblock copolymer (F127, (EO)106(PO)70(EO)106, EO = ethylene oxide, PO = propylene oxide), followed by calcination. The self-assembly structure can be tuned by introducing water in a controlled manner through the control of the humidity level in the surrounding of the as-cast films during aging stage. For the given Fe(NO3)3 · 6H2O:F127 ratio, there appear to be three different thermodynamically stable self-assembly structures depending on the water content in the film material, which correspond to mesoporous, spherical micellar, and rod-like micellar structures after removal of F127. Coupled with the thermodynamic driving forces, the kinetics of the irreversible reactions of coalescence of iron oxide hydroxide particles into larger ones induce diverse nanostructures of the resultant films. The length scale of so-obtained nanostructures ranges from 6 nm to a few hundred nanometers. In addition to water content, the effects of other experimental parameters such as aging temperature, spin rate during spin coating, type of substrate, and type of iron reagent were investigated.

  5. HECLA experiments on interaction between metallic melt and hematite-containing concrete

    Energy Technology Data Exchange (ETDEWEB)

    Sevon, Tuomo, E-mail: tuomo.sevon@vtt.f [VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044 VTT, Espoo (Finland); Kinnunen, Tuomo; Virta, Jouko; Holmstroem, Stefan; Kekki, Tommi; Lindholm, Ilona [VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044 VTT, Espoo (Finland)

    2010-10-15

    In a hypothetical severe accident in a nuclear power plant, molten materials may come into contact with concrete, causing concrete ablation. In five HECLA experiments the interaction between metallic melt and concrete was investigated by pouring molten stainless steel at almost 1800 {sup o}C into cylindrical concrete crucibles. The tests were transient, i.e. no decay heat simulation was used. The main objective was to test the behavior of the FeSi concrete, containing hematite (Fe{sub 2}O{sub 3}) and siliceous aggregates. This special concrete type is used as a sacrificial layer in the Olkiluoto 3 EPR reactor pit, and very scarce experimental data is available about its behavior at high temperatures. It is concluded that no clear differences between the ablation of FeSi concrete and ordinary siliceous concrete were observed. The ablation depths were small, 25 mm at maximum. No dramatic effects, such as cracking of large pieces of concrete due to the thermal shock, took place. An important side result of the test series was gaining knowledge of the properties of the special concrete type. Chemical analyses were conducted and mechanical properties were measured.

  6. SEDIMENTARY LOW-MANGANESE HEMATITE DEPOSITS OF THE BUKOVICA AREA IN THE NORTHWESTERN MT. PETROVA GORA, CENTRAL CROATIA

    Directory of Open Access Journals (Sweden)

    Milivoj Čop

    1998-12-01

    Full Text Available Middle-Permian Gröden deposits crop out on the surface of 0.8 km in the Bukovica area and on the surface of 0.8 km2 in the Mt. Loskun-jska gora in the NW part of the Petrova gora Mountain. One half of the Bukovica Gröden deposits contains in its lowest parts 1 to 5 m (in average 2.5 m thick hematite bed cutted in blocks by NE-SW stretch¬ing vertical, normal and reverse faults. The hematite bed is unconfor-mably underlain by Lower Permian quartz-wackes (subgraywackes intercalated with shales intercalations. Ore deposit is explored by 308 boreholes (10509 m and by numerous adits, inclines and crosscuts on the underground surface of 0.4 km2 . From 1936 to 1941 and from 1953 to 1969 has been exploited 183000 t of ore with (in wt %: 34.0 Si02, 2.9 Al2O3; 59.0 Fe203; 0.15 MnO; 0.7 CaO; 0.4 MgO; 0.1 P, 0.37 S; 1.25 l.o. ign. Proven remaining ore reserves are 250.000 t. Paragenesis is investigated by microscopy of thin and polished sections, XRD, DTA, AAS analyses and by sedimentological analyses. Paragenesis major minerals are of hematite and quartz, with subordinate stable litho-clasts, muscovite (sericite and scarce kaolinite, calcite, dolomite, and barite. Accessories are zircon, rutile, tourmaline, amphibole, garnet, apatite. Epigenetic veinlets and small nests are built up of quartz or calcite as the main neominerals associated with siderite, barite, kaolinite, pyrite, gypsum. Iron from the Bukovica hematite ore origi¬nated by land weathering during hot climate and transported by rivers and underground waters deposited in river beds, in flood plains and in shallow sea. Precipitation of the Bukovica iron ores took place after the Saalic orogenetic phase. At Hrastno (SE Slovenia and at Rude nearby Samobor (Croatia, similar hematite deposits were found.

  7. Geospatial compilation of historical water-level changes in the Chicot and Evangeline aquifers 1977-2013 and Jasper aquifer 2000-13, Gulf Coast aquifer system, Houston-Galveston region, Texas

    Science.gov (United States)

    Johnson, Michaela R.; Linard, Joshua I.

    2014-01-01

    The U.S. Geological Survey (USGS) in cooperation with the Harris-Galveston Subsidence District, City of Houston, Fort Bend Subsidence District, Lone Star Groundwater Conservation District, and Brazoria County Groundwater Conservation District has produced an annual series of reports that depict water-level changes in the Chicot, Evangeline, and Jasper aquifers of the Gulf Coast aquifer system in the Houston-Galveston region, Texas, from 1977 to 2013. Changes are determined from water-level measurements between December and March of each year from groundwater wells screened in one of the three aquifers. Existing published maps and unpublished geographic information system (GIS) datasets were compiled into a comprehensive geodatabase of all water-level-change maps produced as part of this multiagency effort. Annual water-level-change maps were georeferenced and digitized where existing GIS data were unavailable (1979–99). Existing GIS data available for 2000–13 were included in the geodatabase. The compilation contains 121 datasets showing water-level changes for each primary aquifer of the Gulf Coast aquifer system: 56 for the Chicot aquifer (1977; 1979–2013 and 1990; 1993–2013), 56 for the Evangeline aquifer (1977; 1979–2013 and 1990; 1993–2013), and 9 for the Jasper aquifer (2000; 2005–13).

  8. Water-level altitudes 2009 and water-level changes in the Chicot, Evangeline, and Jasper Aquifers and compaction 1973-2008 in the Chicot and Evangeline Aquifers, Houston-Galveston Region, Texas

    Science.gov (United States)

    Kasmarek, Mark C.; Houston, Natalie A.; Ramage, Jason K.

    2009-01-01

    This report, done in cooperation with the Harris-Galveston Subsidence District, the City of Houston, the Fort Bend Subsidence District, and the Lone Star Groundwater Conservation District, is one in an annual series of reports that depicts water-level altitudes and water-level changes in the Chicot, Evangeline, and Jasper aquifers, and compaction in the Chicot and Evangeline aquifers in the Houston-Galveston region, Texas. The report (excluding appendixes) contains 16 sheets and 15 tables: 3 sheets are maps showing current-year (2009) water-level altitudes for each aquifer, respectively; 3 sheets are maps showing 1-year (2008-09) water-level changes for each aquifer, respectively; 3 sheets are maps showing 5-year (2004-09) water-level changes for each aquifer, respectively; 4 sheets are maps showing long-term (1990-2009 and 1977-2009) water-level changes for the Chicot and Evangeline aquifers, respectively; 1 sheet is a map showing long-term (2000-2009) water-level change for the Jasper aquifer; 1 sheet is a map showing site locations of borehole extensometers; and 1 sheet comprises graphs showing measured compaction of subsurface material at the sites from 1973 or later through 2008, respectively. Tables listing the data used to construct the aquifer-data maps and the compaction graphs are included.

  9. Geospatial compilation of historical water-level altitudes in the Chicot and Evangeline aquifers 1977-2013 and Jasper aquifer 2000-13 in the Gulf Coast aquifer system, Houston-Galveston Region, Texas

    Science.gov (United States)

    Johnson, Michaela R.; Ellis, Robert H.H.

    2013-01-01

    The U.S. Geological Survey (USGS) in cooperation with the Harris-Galveston Subsidence District, City of Houston, Fort Bend Subsidence District, Lone Star Groundwater Conservation District, and Brazoria County Groundwater Conservation District has produced a series of annual reports depicting groundwater-level altitudes in the Chicot, Evangeline, and Jasper aquifers of the Gulf Coast aquifer system in the Houston-Galveston region, Texas. To produce these annual reports, contours of equal water-level altitudes are created from water levels measured between December and March of each year from groundwater wells screened completely within one of these three aquifers. Information obtained from maps published in the annual series of USGS reports and geospatial datasets of water-level altitude contours used to create the annual series of USGS reports were compiled into a comprehensive geodatabase. The geospatial compilation contains 88 datasets from previously published contour maps showing water-level altitudes for each primary aquifer of the Gulf Coast aquifer system, 37 for the Chicot (1977–2013), 37 for the Evangeline aquifer (1977–2013), and 14 for the Jasper aquifer (2000–13).

  10. A geochemical view into continental palaeotemperatures of the end-Permian using oxygen and hydrogen isotope composition of secondary silica in chert rubble breccia: Kaibab Formation, Grand Canyon (USA).

    Science.gov (United States)

    Kenny, Ray

    2018-01-16

    The upper carbonate member of the Kaibab Formation in northern Arizona (USA) was subaerially exposed during the end Permian and contains fractured and zoned chert rubble lag deposits typical of karst topography. The karst chert rubble has secondary (authigenic) silica precipitates suitable for estimating continental weathering temperatures during the end Permian karst event. New oxygen and hydrogen isotope ratios of secondary silica precipitates in the residual rubble breccia: (1) yield continental palaeotemperature estimates between 17 and 22 °C; and, (2) indicate that meteoric water played a role in the crystallization history of the secondary silica. The continental palaeotemperatures presented herein are broadly consistent with a global mean temperature estimate of 18.2 °C for the latest Permian derived from published climate system models. Few data sets are presently available that allow even approximate quantitative estimates of regional continental palaeotemperatures. These data provide a basis for better understanding the end Permian palaeoclimate at a seasonally-tropical latitude along the western shoreline of Pangaea.

  11. Final Report For Independent Confirmatory Survey Summary And Results For The Hematite Decommissioning Project, Festus, Missouri

    International Nuclear Information System (INIS)

    Bailey, Erika N.; Lee, Jason D.

    2012-01-01

    ORAU conducted confirmatory surveys of the Hematite site during the period of June 12 through June 13, 2012. The survey activities included in-process inspections, document review, walkover surveys, sampling activities, and laboratory analysis of split samples. WEC was forthcoming with information relating to practices, procedures, and surface scan results. Scans performed by the WEC technician were extremely thorough and methodical. The WEC and ORAU technicians identified the same areas of elevated activity with comparable detector responses. WEC sampling of re-use soils, waste soils, sediments, and groundwater were conducted under ORAU observation. The sampling efforts observed by ORAU were performed in accordance with site-specific procedures and in a manner sufficient to provide quality supporting data. Three observations were made during groundwater sampling activities. First, the water level indicator was re-used without submitting rinse blank. Second, bubbles created during tubing extraction could indicate the presence of volatilized organic compounds. Third, samplers did not use a photo ionization detector prior to sample collection to indicate the presence of volatile organic vapors. Results of split samples indicated a high level of comparability between the WEC and ORAU/ORISE radiological laboratories. Analytical practices and procedures appear to be sufficient in providing quality radiochemical data. All concentrations from the Soil Re-Use Area and sediment samples are below Uniform radionuclide-specific derived concentration guideline level (DCGL W ) limits; thus, comparisons to the less conservative stratified geometry were not required. Results were compared to individual DCGLs and using the sum of fractions approach. Both composite soil samples collected from the Waste Handling Area (Bins 1 and 4) were well below the prescribed USEI waste acceptance criteria

  12. Surface termination dependence of the reactivity of single crystal hematite with CCl 4

    Science.gov (United States)

    Camillone, Nicholas, III; Adib, Kaveh; Fitts, Jeffrey P.; Rim, Kwang T.; Flynn, George W.; Joyce, S. A.; Osgood, Richard M.

    2002-06-01

    We describe ultrahigh vacuum Auger electron spectrometric measurements of the uptake of chlorine following the room temperature exposure of single crystal hematite, α-Fe2O3, to CCl4. We compare the surface chemistry of two specific surface phases formed on the basal plane of α-Fe2O3: the Fe3O4(1 1 1)-(2×2) ;selvedge; and the α-Fe2O3/Fe1-xO ;biphase.; For Fe3O4(1 1 1)-(2×2) an estimated saturation level of Cl of ∼75% of a monolayer is readily attained. Carbon uptake is well below that expected for simple stoichiometric dissociative chemisorption, consistent with desorption of organic products during the surface reaction. Low energy electron diffraction measurements suggest that, dependent upon preparation procedures, at least two types of α-Fe2O3/Fe1-xO biphase structures can be formed. Surprisingly, upon exposure to CCl4, Cl uptake does not occur on either of these biphase surfaces, despite the fact that these surfaces are thought to have the same surface concentrations of iron and oxygen as Fe3O4(1 1 1). The dramatic difference between the reactivity of the Fe3O4 and biphase surfaces suggests that the active site for the dissociative adsorption of CCl4 on Fe3O4(1 1 1)-(2×2) comprises both an iron cation and an oxygen anion with a surface-normal-oriented dangling bond that is uncapped by iron cations. Electron stimulated and thermal desorption of Cl from the saturated Fe3O4(1 1 1)-(2×2) selvedge is also reported.

  13. The calculated solubilities of hematite, magnetite and lepidocrocite in steam generator feedtrains

    International Nuclear Information System (INIS)

    Jobe, D.

    1997-05-01

    The solubility of three iron oxides [hematite (α-Fe 2 O 3 (s)), magnetite (Fe 3 O 4 (s)) and lepidocrocite (γ-FeOOH(s))] under representative steam generator feedtrain conditions were calculated using a thermodynamic database for these oxides and the associated aqueous species. Using this database, we calculated the solubility of iron for both Fe 3 O 4 (s) in equilibrium with other iron oxides and for the individual oxides in the presence of various oxygen partial pressures. The results indicate that the solubility of iron is strongly dependent on redox conditions, represented either by dissolved H 2 or O 2 concentration, or by the presence of other iron oxides (stable or metastable). The solubility behaviour of these oxides can be explained by changes in the aqueous-phase speciation of iron with temperature and pH. Similar calculations for the individual oxides in the presence Of O 2 (g) are also presented and were used to construct temperature-dependent phase diagrams for these oxides in equilibrium (including metastable conditions) with 1 ppb (ppb - μg·kg -1 ) of soluble iron. Calculations were also performed for feedtrain solutions containing 5 ppb of dissolved oxygen and pH buffered using mixtures of amines. From these calculations it was concluded that, relative to the oxidation potential and temperature of the feedtrain solution, changing the pH-buffer has only a minor effect on iron solubility. The effect of the variation in iron solubility along the feedtrain with solution pH, temperature and redox potential on corrosion-product transport to the boiler is also discussed. (author)

  14. Synthesis, structural, optical and morphological characterization of hematite through the precipitation method: Effect of varying the nature of the base

    Science.gov (United States)

    Lassoued, Abdelmajid; Lassoued, Mohamed Saber; Dkhil, Brahim; Gadri, Abdellatif; Ammar, Salah

    2017-08-01

    Iron oxide (α-Fe2O3) nanoparticles were synthesized using the precipitation synthesis method focusing only on (FeCl3, 6H2O), NaOH, KOH and NH4OH as raw materials. The impact of varying the nature of the base on the crystalline phase, size and morphology of α-Fe2O3 products was explored. XRD spectra revealed that samples crystallize in the rhombohedral (hexagonal) system at 800 °C.The Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM) were used to detect the morphology of synthesized nanoparticles and specify their sizes. However, the Fourier Transform Infra-Red (FT-IR) spectroscopy has permitted the observation of vibration band Fe-O. Raman spectroscopy was used not only to prove that we have synthesized hematite but also to identify their phonon modes. The Thermo Gravimetric Analysis (TGA) findings allow the thermal cycle determination of samples whereas Differential Thermal Analysis (DTA) findings allow the phase transition temperature identification. Besides, the optical investigation revealed that samples have an optical gap of about 2.1 eV. Findings highlight that the nature of the agent precipitant plays a significant role in the morphology of the products and the formation of the crystalline phase. Hematite synthesis with the base NH4OH brought about much stronger, sharper and wider diffraction peaks of α-Fe2O3. The morphology of samples are spherical with a size of about 61 nm while the size of the nanoparticles of hematite which we have synthesized with NaOH and KOH is respectively of the order of 82 and 79 nm.

  15. Pyrite oxidation in the presence of hematite and alumina: I. Batch leaching experiments and kinetic modeling calculations.

    Science.gov (United States)

    Tabelin, Carlito Baltazar; Veerawattananun, Suchol; Ito, Mayumi; Hiroyoshi, Naoki; Igarashi, Toshifumi

    2017-02-15

    Pyrite is one of the most common and geochemically important sulfide minerals in nature because of its role in the redox recycling of iron (Fe). It is also the primary cause of acid mine drainage (AMD) that is considered as a serious and widespread problem facing the mining and mineral processing industries. In the environment, pyrite oxidation occurs in the presence of ubiquitous metal oxides, but the roles that they play in this process remain largely unknown. This study evaluates the effects of hematite (α-Fe 2 O 3 ) and alumina (α-Al 2 O 3 ) on pyrite oxidation by batch-reactor type experiments, surface-sensitive characterization of the oxidation layer and thermodynamic/kinetic modeling calculations. In the presence of hematite, dissolved sulfur (S) concentration dramatically decreased independent of the pH, and the formation of intermediate sulfoxy anionic species on the surface of pyrite was retarded. These results indicate that hematite minimized the overall extent of pyrite oxidation, but the kinetic model could not explain how this suppression occurred. In contrast, pyrite oxidation was enhanced in the alumina suspension as suggested by the higher dissolved S concentration and stronger infrared (IR) absorption bands of surface-bound oxidation products. Based on the kinetic model, alumina enhanced the oxidative dissolution of pyrite because of its strong acid buffering capacity, which increased the suspension pH. The higher pH values increased the oxidation of Fe 2+ to Fe 3+ by dissolved O 2 (DO) that enhanced the overall oxidative dissolution kinetics of pyrite. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Synthesis, morphology and microstructure of pomegranate-like hematite (α-Fe2O3) superstructure with high coercivity

    International Nuclear Information System (INIS)

    Tadic, Marin; Citakovic, Nada; Panjan, Matjaz; Stanojevic, Boban; Markovic, Dragana; Jovanovic, Đorđe; Spasojevic, Vojislav

    2012-01-01

    Highlights: ► We found superior magnetic properties of the hematite (α-Fe 2 O 3 ). ► TEM and HRTEM images show a pomegranate-like superstructure. ► Magnetic measurements display high coercivity H C = 4350 Oe at the room temperature. - Abstract: We found novel and superior magnetic properties of the hematite (α-Fe 2 O 3 ) that originate from an internal microstructure of particles and strong inter-particle interactions between nanocrystal sub-units. The hematite particles were synthesized by thermal decomposition of iron (III) nitrate without any template or surfactant. The purity, size, crystallinity, morphology, microstructure and magnetic features of the as-prepared particles were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), Raman spectroscopy (RS) and SQUID magnetometry. An XRD study reveals a pure phase of α-Fe 2 O 3 whereas TEM shows α-Fe 2 O 3 spheres with a diameter of about 150 nm. RS also shows high quality and purity of the sample. Moreover, TEM and HRTEM images show a pomegranate-like superstructure and evidence that the spherical particles are composed of individual well-crystallized nanoparticle sub-units (self-assembled nanoparticles) with a size of about 20 nm. Magnetic measurements display hysteretic behavior at the room temperature with remanent magnetization M r = 0.731 emu/g, saturation magnetization M S = 6.83 emu/g and coercivity H C = 4350 Oe, as well as the Morin transition at T M = 261 K. These results and comparison with those in the literature reveal that the sample has extremely high coercivity. The magnetic properties of the sample are discussed in relation to morphology, internal microstructure, surface effects and exchange and dipole–dipole interactions.

  17. Observations of surface-mediated reduction of Pu(VI) to Pu(IV) on hematite nanoparticles by ATR FT-IR

    Energy Technology Data Exchange (ETDEWEB)

    Emerson, Hilary P. [Florida International Univ., Applied Research Center, Miami, FL (United States); Powell, Brian A. [Clemson Univ., Dept. of Enviromental Engineering and Earth Sciences, Anderson, SC (United States)

    2015-07-01

    Previous studies have shown that mineral surfaces may facilitate the reduction of plutonium though the mechanisms of the reduction are still unknown. The objective of this study is to use batch sorption and attenuated total reflectance Fourier transform infrared spectroscopy experiments to observe the surface-mediated reduction of plutonium on hematite nanoparticles. These techniques allow for in situ measurement of reduction of plutonium with time and may lead to a better understanding of the mechanisms of surface mediated reduction of plutonium. For the first time, ATR FT-IR peaks for Pu(VI) sorbed to hematite are measured at ∝ 916 cm{sup -1}, respectively. The decrease in peak intensity with time provides a real-time, direct measurement of Pu(VI) reduction on the hematite surface. In this work pseudo first order rate constants estimated at the high loadings (22 mg{sub Pu}/g{sub hematite}, 1.34 x 10{sup -6} M{sub Pu}/m{sup 2}) for ATR FT-IR are approximately 10 x slower than at trace concentrations based on previous work. It is proposed that the reduced rate constant at higher Pu loadings occurs after the reduction capacity due to trace Fe(II) has been exhausted and is dependent on the oxidation of water and possibly electron shuttling based on the semiconducting nature of hematite. Therefore, the reduction rate at higher loadings is possibly due to the thermodynamic favorability of Pu(IV)-hydroxide complexes.

  18. Pressure response of vacancy ordered maghemite ({gamma}-Fe{sub 2}O{sub 3}) and high pressure transformed hematite ({alpha}-Fe{sub 2}O{sub 3})

    Energy Technology Data Exchange (ETDEWEB)

    Hearne, Giovanni, E-mail: grhearne@uj.ac.za [Department of Physics, University of Johannesburg, PO Box 524, Auckland Park, 2006 Johannesburg (South Africa); Pischedda, Vittoria, E-mail: Vittoria.Pischedda@univ-lyon1.fr [Laboratoire de Physique de la Matiere Condensee et Nanostructures, University Lyon 1 and CNRS, 69622 Villeurbanne Cedex (France)

    2012-03-15

    Combined XRD and Moessbauer effect spectroscopy studies to high pressures of {approx}30 GPa of vacancy ordered maghemite are presented. The vacancy ordered superstructure is robust and remains intact up to the pressure-induced onset transition to hematite at 13-16 GPa. The pressure transformed hematite is shown to be crystallographically textured, unlike the randomised low pressure maghemite phase. This arises out of a pressure or stress instigated topotactic transformation of the cubic-spinel to hexagonal-corundum structure. The textured sample permits us to obtain information on the spin reorientation behavior of the pressure transformed hematite in compression and decompression sequences. Spin reorientation is restricted to {approx}15 Degree-Sign over wide pressure ranges, attributable to the effect of entrapped vacancies in the high pressure structure. Thus there are structural and magnetic peculiarities specific to pressure transformed hematite not evident in pressurized hematite starting material. These are triggered by the maghemite{yields}hematite transformation. - Graphical abstract: Pressure instigated topotactic transformation of vacancy ordered {gamma}-Fe{sub 2}O{sub 3}{yields}{alpha}-Fe{sub 2}O{sub 3}. There is restricted spin (B{sub hf}) reorientation in the new pressure transformed hematite due to entrapped vacancies. The change in direction of V{sub zz} signifies a distortion of the FeO{sub 6} octahedral local environment. Highlights: Black-Right-Pointing-Pointer Robust vacancy ordered superstructure in maghemite to high pressures. Black-Right-Pointing-Pointer Pressure instigated topotactic transformation to hematite and subsequent texture. Black-Right-Pointing-Pointer Defect trapping in the pressure transformed hematite. Black-Right-Pointing-Pointer Entrapped defects restricts spin reorientation in pressure transformed hematite. Black-Right-Pointing-Pointer Contrasting behavior with pressurized hematite starting material.

  19. Hea uljas pingviiniilm / Jasper Zoova

    Index Scriptorium Estoniae

    Zoova, Jasper

    2003-01-01

    Nukufilm "Pingviinide paraad" : stsenaarium, lavastus ja kujundus Julia Pihlak, Riho Unt : operaator Urmas Jõemees : produtsent Arvo Nuut : Nukufilm 2002. Lisatud Julia Pihlaku ja Riho Undi filmograafia lk. 93

  20. Experimental Acid Weathering of Fe-Bearing Mars Analog Minerals and Rocks: Implications for Aqueous Origin of Hematite-Bearing Sediments in Meridiani Planum, Mars

    Science.gov (United States)

    Golden, D. C.; Koster, A. M.; Ming, D. W.; Morris, R. V.; Mertzman, S. A.

    2011-01-01

    A working hypothesis for Meridiani evaporite formation involves the evaporation of fluids derived from acid weathering of Martian basalts and subsequent diagenesis [1, 2]. However, there are no reported experimental studies for the formation of jarosite and gray hematite (spherules), which are characteristic of Meridiani rocks from Mars analog precursor minerals. A terrestrial analog for hematite spherule formation from basaltic rocks under acidic hydrothermal conditions has been reported [3], and we have previously shown that the hematite spherules and jarosite can be synthetically produced in the laboratory using Fe3+ -bearing sulfate brines under hydrothermal conditions [4]. Here we expand and extend these studies by reacting Mars analog minerals with sulfuric acid to form Meridiani-like rock-mineral compositions. The objective of this study is to provide environmental constraints on past aqueous weathering of basaltic materials on Mars.

  1. The different climatic response of pedogenic hematite and ferrimagnetic minerals: Evidence from particle-sized modern soils over the Chinese Loess Plateau

    Science.gov (United States)

    Gao, Xinbo; Hao, Qingzhen; Wang, Luo; Oldfield, Frank; Bloemendal, Jan; Deng, Chenglong; Song, Yang; Ge, Junyi; Wu, Haibin; Xu, Bing; Li, Fengjiang; Han, Long; Fu, Yu; Guo, Zhengtang

    2018-01-01

    In recent years, increasing interest in loess studies has focused on qualitative and quantitative paleoclimatic reconstruction using the imperfect antiferromagnetic mineral hematite. However, the linkage between the hematite formation and climatic variables remains controversial. Here we present the results of a comprehensive investigation of the magnetic properties and statistical analysis of a suite of clay and silt fractions of modern soil samples from 179 sites across the Chinese Loess Plateau (CLP) and adjacent regions. Our objective was to clarify the relationships between modern climatic variables and pedogenic hematite, as well as pedogenic ferrimagnetic minerals. First-order reversal curve measurements were also conducted on representative particle-sized subsamples from a N-S transect to understand the differences in magnetic mineralogy between the two fractions. Our results show that pipette extraction separates the fine-grained superparamagnetic (SP) and most of the single-domain (SD) magnetic grains into the clay fraction, and that the remaining silt fraction displays the magnetic properties of coarse pseudo-single domain (PSD) or a mixture of multidomain (MD)/PSD and a few SD particles. Only the pedogenic clay fraction shows a strong correlation with climatic variables. The application of redundancy analysis helps to distinguish the climate variables controlling the formation of ferrimagnetic minerals and hematite during pedogenesis. On the CLP, pedogenic ferrimagnetic minerals are sensitive to mean annual precipitation, while pedogenic hematite formation is preferentially dependent on mean annual temperature. The confirmation of the temperature-dependent nature of hematite on the CLP provides a new possibility for quantitatively reconstructing the paleotemperature history of Chinese loess/paleosol sequences.

  2. Iron insertion and hematite segregation on Fe-doped TiO2 nanoparticles obtained from sol-gel and hydrothermal methods.

    Science.gov (United States)

    Santos, Reginaldo da S; Faria, Guilherme A; Giles, Carlos; Leite, Carlos A P; Barbosa, Herbert de S; Arruda, Marco A Z; Longo, Claudia

    2012-10-24

    Iron-doped TiO(2) (Fe:TiO(2)) nanoparticles were synthesized by the sol-gel method (with Fe/Ti molar ratio corresponding to 1, 3, and 5%), followed by hydrothermal treatment, drying, and annealing. A similar methodology was used to synthesize TiO(2) and α-Fe(2)O(3) nanoparticles. For comparison, a mixture hematite/titania, with Fe/Ti = 4% was also investigated. Characterization of the samples using Rietveld refinement of X-ray diffraction data revealed that TiO(2) consisted of 82% anatase and 18% brookite; for Fe:TiO(2), brookite increased to 30% and hematite was also identified (0.5, 1.0, and 1.2 wt % for samples prepared with 1, 3, and 5% of Fe/Ti). For hematite/titania mixture, Fe/Ti was estimated as 4.4%, indicating the Rietveld method reliability for estimation of phase composition. Because the band gap energy, estimated as 3.2 eV for TiO(2), gradually ranged from 3.0 to 2.7 eV with increasing Fe content at Fe:TiO(2), it can be assumed that a Fe fraction was also inserted as dopant in the TiO(2) lattice. Extended X-ray absorption fine structure spectra obtained for the Ti K-edge and Fe K-edge indicated that absorbing Fe occupied a Ti site in the TiO(2) lattice, but hematite features were not observed. Hematite particles also could not be identified in the images obtained by transmission electron microscopy, in spite of iron identification by elemental mapping, suggesting that hematite can be segregated at the grain boundaries of Fe:TiO(2).

  3. Deposition of hematite particles on alumina seal faceplates of nuclear reactor coolant pumps: Laboratory experiments and industrial feedback

    Directory of Open Access Journals (Sweden)

    Lefèvre Grégory

    2012-01-01

    Full Text Available In the primary circuit of pressurized water reactors (PWR, the dynamic sealing system in reactor coolant pumps is ensured by mechanical seals whose ceramic parts are in contact with the cooling solution. During the stretch-out phase in reactor operation, characterized by low boric acid concentration, the leak-off flow has been observed to abnormally evolve in industrial plants. The deposition of hematite particles, originating from corrosion, on alumina seals of coolant pumps is suspected to be the cause. As better understanding of the adhesion mechanism is the key factor in the prevention of fouling and particle removal, an experimental study was carried out using a laboratory set-up. With model materials, hematite and sintered alumina, the adhesion rate and surface potentials of the interacting solids were measured under different chemical conditions (solution pH and composition in analogy with the PWR ones. The obtained results were in good agreement with the DLVO (Derjaguin-Landau-Verwey- Overbeek theory and used as such to interpret this industrial phenomenon.

  4. Effect of EDTA on quartz and hematite flotation with starch/amine in an aqueous solution containing Mn2+ ions

    Directory of Open Access Journals (Sweden)

    Deisiane Ferreira Lelis

    Full Text Available Abstract In this paper, a detailed study of the influence of Mn2+ ions on quartz and hematite flotation (at pH 10.5 with starch/amine as depressor/collector in the absence and presence of ethylenediaminetetraacetic acid (EDTA is presented. By using zeta potential measurement and a careful analysis of manganese species present in water for dosages in which manganese hydroxide precipitated, we confirmed that the depression of both minerals by Mn2+ ions is due to the following: (i the adsorption of Mn hydroxy complexes (Mn2(OH3+ and Mn(OH+; (ii Mn2+ and mainly (iii the precipitation of Mn(OH2 on mineral surfaces. These effects hindered the adsorption of amine species on the surfaces of the minerals (quartz and hematite. EDTA was used to complex Mn2+ to restore the recoveries of both minerals. This was confirmed by the species distribution diagrams of Mn and EDTA-Mn in water. Conditioning with starch followed by amine at pH 10.5 enabled a selective separation of these minerals.

  5. In situ spectroscopic identification of neptunium(V) inner-sphere complexes on the hematite-water interface.

    Science.gov (United States)

    Müller, Katharina; Gröschel, Annett; Rossberg, André; Bok, Frank; Franzen, Carola; Brendler, Vinzenz; Foerstendorf, Harald

    2015-02-17

    Hematite plays a decisive role in regulating the mobility of contaminants in rocks and soils. The Np(V) reactions at the hematite-water interface were comprehensively investigated by a combined approach of in situ vibrational spectroscopy, X-ray absorption spectroscopy and surface complexation modeling. A variety of sorption parameters such as Np(V) concentration, pH, ionic strength, and the presence of bicarbonate was considered. Time-resolved IR spectroscopic sorption experiments at the iron oxide-water interface evidenced the formation of a single monomer Np(V) inner-sphere sorption complex. EXAFS provided complementary information on bidentate edge-sharing coordination. In the presence of atmospherically derived bicarbonate the formation of the bis-carbonato inner-sphere complex was confirmed supporting previous EXAFS findings.1 The obtained molecular structure allows more reliable surface complexation modeling of recent and future macroscopic data. Such confident modeling is mandatory for evaluating water contamination and for predicting the fate and migration of radioactive contaminants in the subsurface environment as it might occur in the vicinity of a radioactive waste repository or a reprocessing plant.

  6. Template free fabrication of hollow hematite spheres via a one-pot polyoxometalate-assisted hydrolysis process

    International Nuclear Information System (INIS)

    Mao Baodong; Kang Zhenhui; Wang Enbo; Tian Chungui; Zhang Zhiming; Wang Chunlei; Song Yanli; Li Meiye

    2007-01-01

    Uniform hollow hematite (α-Fe 2 O 3 ) spheres with diameter of about 600-700 nm and shell thickness lower than 100 nm are obtained by direct hydrothermal treatment of dilute FeCl 3 and tungstophosphoric acid H 3 PW 12 O 40 solution at 180 deg. C. The hollow spheres are composed of robust shells with small nanoparticles standing out of the surface and present a high-surface area and a weak ferromagnetic behavior at room temperature. The effect of concentration of H 3 PW 12 O 40 , reaction time and temperature for the formation of the hollow spheres are investigated in series of experiments. The formation of the hollow spheres may be ascribed to a polyoxometalte-assisted forced hydrolysis and dissolution process. - Graphical abstract: Uniform hollow hematite (α-Fe 2 O 3 ) spheres with diameter of about 600-700 nm and shell thickness lower than 100 nm are obtained by direct hydrothermal treatment of dilute FeCl 3 and tungstophosphoric acid H 3 PW 12 O 40 solution at 180 deg. C. The hollow spheres present a high surface area and weak ferromagnetic behavior at room temperature

  7. Enhanced photoelectrochemical performance of Ti-doped hematite thin films prepared by the sol-gel method

    Energy Technology Data Exchange (ETDEWEB)

    Lian Xiaojuan; Yang Xin; Liu Shangjun; Xu Ying; Jiang Chunping; Chen Jinwei [College of Materials Science and Engineering, Sichuan University, No.24 South Section 1, Yihuan Road, Chengdu 610065 (China); Wang Ruilin, E-mail: rlwang26@yahoo.com.cn [College of Materials Science and Engineering, Sichuan University, No.24 South Section 1, Yihuan Road, Chengdu 610065 (China)

    2012-01-15

    Ti-doped {alpha}-Fe{sub 2}O{sub 3} thin films were successfully prepared on FTO substrates by the sol-gel route. Hematite film was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and energy dispersive spectrometer (EDS). The XRD data showed {alpha}-Fe{sub 2}O{sub 3} had a preferred (1 1 0) orientation which belonged to the rhombohedral system. Interestingly, the grains turned into worm-like shape after annealed at high temperature. The IPCE could reach 32.6% at 400 nm without any additional potential vs. SCE. Titanium in the lattice can affect the photo electro chemical performance positively by increasing the conductivity of the thin film. So the excited electrons and holes could live longer, rather than recombining with each other rapidly as undoped hematite. And the efficient carrier density on the Ti-doped anode surface was higher than the undoped anode, which contribute to the well PEC performance.

  8. Method for Transformation of Weakly Magnetic Minerals (Hematite, Goethite into Strongly Magnetic Mineral (Magnetite to Improve the Efficiency of Technologies for Oxidized Iron Ores Benefication

    Directory of Open Access Journals (Sweden)

    Ponomarenko, O.

    2015-03-01

    Full Text Available A new method for relatively simple transformation of weakly magnetic minerals (goethite (α-FeOOH and hematite (α-Fe2O3 into strongly magnetic mineral (magnetite (Fe3O4 was developed. It was shown, that transformation of structure and magnetic characteristics of go ethite and hematite are realized in the presence of starch at relatively low temperatures (in the range of 300—600 °С. Obtained results open up new possibilities for development of effective technologies for oxidized iron ore beneficiation.

  9. Water-level altitudes 2011 and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction 1973-2010 in the Chicot and Evangeline aquifers, Houston-Galveston region, Texas

    Science.gov (United States)

    Johnson, Michaela R.; Ramage, Jason K.; Kasmarek, Mark C.

    2011-01-01

    Most of the subsidence in the Houston–Galveston region has occurred as a direct result of groundwater withdrawals for municipal supply, industrial use, and irrigation that depressured and dewatered the Chicot and Evangeline aquifers causing compaction of the clay layers of the aquifer sediments. This report, prepared by the U.S. Geological Survey, in cooperation with the Harris–Galveston Subsidence District, City of Houston, Fort Bend Subsidence District, and Lone Star Groundwater Conservation District, is one in an annual series of reports depicting water-level altitudes and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction in the Chicot and Evangeline aquifers in the Houston–Galveston region. The report contains maps showing 2011 water-level altitudes for the Chicot, Evangeline, and Jasper aquifers; maps showing 1-year (2010–11) water-level-altitude changes for each aquifer; maps showing 5-year (2006–11) water-level-altitude changes for each aquifer; maps showing long-term (1990–2011 and 1977–2011) water-level-altitude changes for the Chicot and Evangeline aquifers; a map showing long-term (2000–11) water-level-altitude change for the Jasper aquifer; a map showing locations of borehole extensometer sites; and graphs showing measured compaction of subsurface material at the extensometers from 1973, or later, through 2010. Tables listing the data used to construct each aquifer-data map and the compaction graphs are included.Water levels in the Chicot, Evangeline, and Jasper aquifers were measured during December 2010–February 2011. In 2011, water-level-altitude contours for the Chicot aquifer ranged from 200 feet below North American Vertical Datum of 1988 (hereinafter, datum) in a small area in southwestern Harris County to 200 feet above datum in central to southwestern Montgomery County. Water-level-altitude changes in the Chicot aquifer ranged from a 40-foot decline to a 33-foot rise (2010–11), from a 10-foot

  10. Water-level altitudes 2010 and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction 1973-2009 in the Chicot and Evangeline aquifers, Houston-Galveston region, Texas

    Science.gov (United States)

    Kasmarek, Mark C.; Johnson, Michaela R.; Ramage, Jason K.

    2010-01-01

    Most of the subsidence in the Houston-Galveston region has occurred as a direct result of groundwater withdrawals for municipal supply, industrial use, and irrigation that depressured and dewatered the Chicot and Evangeline aquifers causing compaction of the clay layers of the aquifer sediments. This report, prepared by the U.S. Geological Survey, in cooperation with the Harris-Galveston Subsidence District, City of Houston, Fort Bend Subsidence District, and Lone Star Groundwater Conservation District, is one in an annual series of reports depicting water-level altitudes and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction in the Chicot and Evangeline aquifers in the Houston-Galveston region. The report contains maps showing 2010 water-level altitudes for the Chicot, Evangeline, and Jasper aquifers, respectively; maps showing 1-year (2009-10) water-level-altitude changes for each aquifer; maps showing 5-year (2005-10) water-level-altitude changes for each aquifer; maps showing long-term (1990-2010 and 1977-2010) water-level-altitude changes for the Chicot and Evangeline aquifers; a map showing long-term (2000-10) water-level-altitude change for the Jasper aquifer; a map showing locations of borehole extensometer sites; and graphs showing measured compaction of subsurface material at the extensometers from 1973, or later, through 2009. Tables listing the data used to construct each aquifer-data map and the compaction graphs are included. Water levels in the Chicot, Evangeline, and Jasper aquifers were measured during December 2009-March 2010. In 2010, water-level-altitude contours for the Chicot aquifer ranged from 200 feet below National Geodetic Vertical Datum of 1929 or North American Vertical Datum of 1988 (hereinafter, datum) in a small area in southwestern Harris County to 200 feet above datum in central to southwestern Montgomery County. Water-level-altitude changes in the Chicot aquifer ranged from a 49-foot decline to a 67

  11. Synthesis of core-shell hematite (α-Fe2O3) nanoplates: Quantitative analysis of the particle structure and shape, high coercivity and low cytotoxicity

    Science.gov (United States)

    Tadic, Marin; Kopanja, Lazar; Panjan, Matjaz; Kralj, Slavko; Nikodinovic-Runic, Jasmina; Stojanovic, Zoran

    2017-05-01

    Hematite core-shell nanoparticles with plate-like morphology were synthesized using a one-step hydrothermal synthesis. An XRPD analysis indicates that the sample consist of single-phase α-Fe2O3 nanoparticles. SEM and TEM measurements show that the hematite sample is composed of uniform core-shell nanoplates with 10-20 nm thickness, 80-100 nm landscape dimensions (aspect ratio ∼5) and 3-4 nm thickness of the surface shells. We used computational methods for the quantitative analysis of the core-shell particle structure and circularity shape descriptor for the quantitative shape analysis of the nanoparticles from TEM micrographs. The calculated results indicated that a percentage of the shell area in the nanoparticle area (share [%]) is significant. The determined values of circularity in the perpendicular and oblique perspective clearly show shape anisotropy of the nanoplates. The magnetic properties revealed the ferromagnetic-like properties at room temperature with high coercivity HC = 2340 Oe, pointing to the shape and surface effects. These results signify core-shell hematite nanoparticles' for practical applications in magnetic devices. The synthesized hematite plate-like nanoparticles exhibit low cytotoxicity levels on the human lung fibroblasts (MRC5) cell line demonstrating the safe use of these nanoparticles for biomedical applications.

  12. Acquisition of chemical remanent magnetization during experimental ferrihydrite-hematite conversion in Earth-like magnetic field-implications for paleomagnetic studies of red beds

    NARCIS (Netherlands)

    Jiang, Zhaoxia; Liu, Qingsong; Dekkers, Mark J.; Tauxe, Lisa; Qin, Huafeng; Barrón, Vidal; Torrent, José

    2015-01-01

    Hematite-bearing red beds are renowned for their chemical remanent magnetization (CRM). If the CRM was acquired substantially later than the sediment was formed, this severely compromises paleomagnetic records. To improve our interpretation of the natural remanent magnetization, the intricacies of

  13. Magneto-optical effects of reflection on monocrystals of ferrite garnets, orthoferrites hexaferrites and hematite. [Yttrium oxides iron oxides; europium oxides; bismuth oxides

    Energy Technology Data Exchange (ETDEWEB)

    Krinchik, G S; Krylova, V A; Khrebtov, A P; Chepurova, E E

    1975-01-01

    The results of experimental studies of the equatorial Kerr effect in visible and ultraviolet ranges of the spectrum are given for ferromagnetic dielectrics of different classes: ferrimagnetic ferrite garnets and hexaferrites, as well as weakly ferromagnetic orthoferrites and hematite. A method for the nondestructive magneto-optical data readout using reflected light is proposed and described.

  14. Anodic self-organized transparent nanotubular/porous hematite films from Fe thin-films sputtered on FTO and photoelectrochemical water splitting

    Czech Academy of Sciences Publication Activity Database

    Wang, L.; Lee, C.-Y.; Kirchgeorg, R.; Liu, N.; Lee, K.; Kment, Š.; Hubička, Zdeněk; Krýsa, J.; Olejníček, J.; Čada, M.; Zbořil, R.; Schmuki, P.

    2015-01-01

    Roč. 41, č. 12 (2015), s. 9333-9341 ISSN 0922-6168. [Pannonian Symposium on Catalysis /12./. Třešť, 16.09.2014-20.09.2014] Institutional support: RVO:68378271 Keywords : hematite * nanotubular * anodization * magnetron * sputtering * water splitting Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.833, year: 2015

  15. Sensors based on Ag-loaded hematite (α-Fe2O3 nanoparticles for methyl mercaptan detection at room temperature

    Directory of Open Access Journals (Sweden)

    Daniel Garcia

    2017-06-01

    Full Text Available Sensors based on Ag/α-Fe2O3 nanoparticles have been prepared by the coprecipitation method for sensing methyl mercaptan at room temperature. X-ray diffraction patterns of samples matched perfectly with characteristic peaks of hematite with no peaks assigned to Ag even at the highest concentration. STEM images and EDX analysis revealed the presence of Ag nanoparticles (from 2 to 5 nm which were highly dispersed onto α-Fe2O3 surface with an Ag/Fe ratio from 0.014 to 0.099. The Ag nanoparticles were deposited on the hematite surface. Sensing tests of Ag-loaded hematite nanoparticles showed much higher response signal than the unmodified sensor. Hematite loaded with 3%(Wt Ag showed the highest response with a linear dependence from 20 to 80 ppm. The sensor also depicted a good selectivity and stability during 4 days with short recovery time. The high dispersion of reduced Ag evaluated by XPS analysis played an important chemical role in the sensing mechanism that favored the contact of CH3SH with oxygen.

  16. Magnetic properties of ilmenite-hematite single crystals from the Ecstall pluton near Prince Rupert, British Columbia

    DEFF Research Database (Denmark)

    Brownlee, Sarah J.; Feinberg, Joshua M.; Kasama, Takeshi

    2011-01-01

    Paleomagnetic studies of the 91 Ma Ecstall pluton and other Cretaceous plutons of British Columbia imply large northward tectonic movements (>2000 km) may have occurred during the tectonic evolution of western North America. However, more recent studies have shown that the eastern edge...... of the Ecstall pluton experienced considerable mineralogical changes as younger Eocene plutons, such as the ∼58 Ma Quottoon Pluton, were emplaced along its margins. We investigated changes in the rock magnetic properties associated with this reheating event by examining isolated grains of intergrown ilmenite...... and hematite, the primary paleomagnetic recorder in the Ecstall pluton. Measurements of hysteresis properties, low-temperature remanence, and room temperature isothermal remanent magnetization acquisition and observations from magnetic force microscopy and off-axis electron holography indicate that samples...

  17. Neptunium redox behavior and sorption onto goethite and hematite in the presence of humic acids with different hydroquinone content

    International Nuclear Information System (INIS)

    Khasanova, A.B.; Kalmykov, St.N.; Perminova, I.V.; Clark, S.B.

    2007-01-01

    The effect of humic acids (HA) on neptunium redox behavior and sorption onto hematite, α-Fe 2 O 3 , and goethite, α-FeOOH, colloids was established in batch sorption experiments that were carried out in broad pH interval. The sorption isotherms were provided for two samples of HA: commercial sample of leonardite humic acid and its hydroquinone-enriched derivative obtained using formaldehyde copolycondensation. The distribution of Np fitted the distribution of hydroquinone-enriched HA at low pH values in case of both solids while the influence of parent HA on Np sorption was negligible. This is due to Np(V) reduction upon interaction with hydroquinone-enriched derivative having higher reducing capacity compared to the parent HA. The order of components addition was found to be significant for Np retention

  18. Photo-assisted electrochemical oxidation of the urea onto TiO2-nanotubes modified by hematite

    Directory of Open Access Journals (Sweden)

    Waleed M. Omymen

    2017-12-01

    Full Text Available The electrochemical oxidation of the urea in near neutral pH is investigated on platinum electrode. It is shown that oxidation reaction is practically inhibited up to the potentials of ∼0.9 V. The same reaction is investigated onto electrochemically obtained titanium dioxide nanotubes modified by hematite using facile, low-cost successive ion layer adsorption and reaction (SILAR method. It is shown that such system possesses electrocatalytic activity at very low potentials, and activity can be further improved by the illumination of the electrode in the photo-assisted reaction. The possible application of the photoactive anode is considered in the application of urea based water electrolysis and urea based fuel cell. Keywords: Photoelectrochemical cell, Water electrolysis, Fuel cell, SILAR

  19. AMS Fabric of a CRM in Hematite-Bearing Samples: Evidence of DRMs in Natural Red Beds

    Science.gov (United States)

    Kodama, K. P.

    2002-12-01

    Anisotropy of magnetic susceptibility (AMS) and anisotropy of isothermal remanence (AIR) in red sedimentary rocks both typically show a bedding parallel foliation with minimum axes clustered perpendicular to the bedding plane. Our studies have observed this type of magnetic fabric in red bed units that have a range of ages and come from widespread localities. These units include the Mississippian Mauch Chunk Formation from the Appalachians, the Triassic Passaic Formation from the Newark basin in Pennsylvania, the Cretaceous Kapusaliang Formation from the Tarim basin in China, and the early Mesozoic Kayenta and Chinle Formations from the Colorado Plateau in southwestern North America. Bedding parallel foliations are also observed in magnetite-bearing rocks that carry a depositional remanence (DRM), suggesting the possibility of a DRM in red beds, even though the conventional wisdom is that they carry a post-depositional chemical remanent magnetization (CRM). Before the typical magnetic fabric of red beds can be used to indicate their type of remanence, we must determine what the magnetic fabric of a CRM looks like. For this reason, I conducted a series of hematite-growth experiments following the procedures outlined by Stokking and Tauxe (1987). I grew hematite in the laboratory on stacks of glass-fiber filter papers and in slurries of quartz and kaolinite. The hematite was grown from a ferric nitrate solution heated to 95° C for 8 hours. The samples were then dehydrated in a vacuum at room temperature for approximately 38 hours. It was possible to thermally demagnetize the eight filter paper samples to 350° C, but the six kaolinite-quartz samples were grown in plastic sample cubes and could only be thermally demagnetized to 150° C, enough to remove the thermoviscous magnetization acquired by the samples during the heating at 95° C. The mean CRM acquired by the red-brown magnetic phase grown in the experiments was within its alpha-95 of the steeply inclined

  20. Direct Solar Charging of an Organic-Inorganic, Stable, and Aqueous Alkaline Redox Flow Battery with a Hematite Photoanode.

    Science.gov (United States)

    Wedege, Kristina; Azevedo, João; Khataee, Amirreza; Bentien, Anders; Mendes, Adélio

    2016-06-13

    The intermittent nature of the sunlight and its increasing contribution to electricity generation is fostering the energy storage research. Direct solar charging of an auspicious type of redox flow battery could make solar energy directly and efficiently dispatchable. The first solar aqueous alkaline redox flow battery using low cost and environmentally safe materials is demonstrated. The electrolytes consist of the redox couples ferrocyanide and anthraquinone-2,7-disulphonate in sodium hydroxide solution, yielding a standard cell potential of 0.74 V. Photovoltage enhancement strategies are demonstrated for the ferrocyanide-hematite junction by employing an annealing treatment and growing a layer of a conductive polyaniline polymer on the electrode surface, which decreases electron-hole recombination. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. On the impact of non-sphericity and small-scale surface roughness on the optical properties of hematite aerosols

    International Nuclear Information System (INIS)

    Kahnert, Michael; Nousiainen, Timo; Mauno, Paeivi

    2011-01-01

    We perform a comparative modelling study to investigate how different morphological features influence the optical properties of hematite aerosols. We consider high-order Chebyshev particles as a proxy for aerosol with a small-scale surface roughness, and spheroids as a model for nonspherical aerosols with a smooth boundary surface. The modelling results are compared to those obtained for homogeneous spherical particles. It is found that for hematite particles with an absorption efficiency of order unity the difference in optical properties between spheres and spheroids disappears. For optically softer particles, such as ice particles at far-infrared wavelengths, this effect can be observed for absorption efficiencies lower than unity. The convergence of the optical properties of spheres and spheroids is caused by absorption and quenching of internal resonances inside the particles, which depend both on the imaginary part of the refractive index and on the size parameter, and to some extent on the real part of the refractive index. By contrast, small-scale surface roughness becomes the dominant morphological feature for large particles. This effect is likely to depend on the amplitude of the surface roughness, the relative significance of internal resonances, and possibly on the real part of the refractive index. The extinction cross section is rather insensitive to surface roughness, while the single-scattering albedo, asymmetry parameter, and the Mueller matrix are strongly influenced. Small-scale surface roughness reduces the backscattering cross section by up to a factor of 2-3 as compared to size-equivalent particles with a smooth boundary surface. This can have important implications for the interpretation of lidar backscattering observations.

  2. Thermo-mechanical characterization of siliconized E-glass fiber/hematite particles reinforced epoxy resin hybrid composite

    Energy Technology Data Exchange (ETDEWEB)

    Arun Prakash, V.R., E-mail: vinprakash101@gmail.com; Rajadurai, A., E-mail: rajadurai@annauniv.edu.in

    2016-10-30

    when surface modified fiber was reinforced along with hard hematite particles. Thermal conductivity of epoxy increased with increase of hematite content in epoxy matrix.

  3. Spin Crossover and the Magnetic P- T Phase Diagram of Hematite at High Hydrostatic Pressures and Cryogenic Temperatures

    Science.gov (United States)

    Gavriliuk, A. G.; Struzhkin, V. V.; Mironovich, A. A.; Lyubutin, I. S.; Troyan, I. A.; Chow, P.; Xiao, Y.

    2018-02-01

    The magnetic properties of the α-Fe2O3 hematite at a high hydrostatic pressure have been studied by synchrotron Mössbauer spectroscopy (nuclear forward scattering (NFS)) on iron nuclei. Time-domain NFS spectra of hematite have been measured in a diamond anvil cell in the pressure range of 0-72 GPa and the temperature range of 36-300 K in order to study the magnetic properties at a phase transition near a critical pressure of 50 GPa. In addition, Raman spectra at room temperature have been studied in the pressure range of 0-77 GPa. Neon has been used as a pressure-transmitting medium. The appearance of an intermediate electronic state has been revealed at a pressure of 48 GPa. This state is probably related to the spin crossover in Fe3+ ions at their transition from the high-spin state (HS, S = 5/2) to a low-spin one (LS, S = 1/2). It has been found that the transient pressure range of the HS-LS crossover is extended from 48 to 55 GPa and is almost independent of the temperature. This surprising result differs fundamentally from other cases of the spin crossover in Fe3+ ions observed in other crystals based on iron oxides. The transition region of spin crossover appears because of thermal fluctuations between HS and LS states in the critical pressure range and is significantly narrowed at cooling because of the suppression of thermal excitations. The magnetic P- T phase diagram of α-Fe2O3 at high pressures and low temperatures in the spin crossover region has been constructed according to the results of measurements.

  4. Water-level altitudes 2016 and water-level changes in the Chicot, Evangeline, and Jasper aquifers and compaction 1973–2015 in the Chicot and Evangeline aquifers, Houston-Galveston region, Texas

    Science.gov (United States)

    Kasmarek, Mark C.; Ramage, Jason K.; Johnson, Michaela R.

    2016-10-07

    Most of the land-surface subsidence in the Houston-Galveston region, Texas, has occurred as a direct result of groundwater withdrawals for municipal supply, commercial and industrial use, and irrigation that depressured and dewatered the Chicot and Evangeline aquifers, thereby causing compaction of the aquifer sediments, mostly in the fine-grained silt and clay layers. This report, prepared by the U.S. Geological Survey in cooperation with the Harris-Galveston Subsidence District, City of Houston, Fort Bend Subsidence District, Lone Star Groundwater Conservation District, and Brazoria County Groundwater Conservation District, is one in an annual series of reports depicting water-level altitudes and water-level changes in the Chicot, Evangeline, and Jasper aquifers and measured cumulative compaction of subsurface sediments in the Chicot and Evangeline aquifers in the Houston-Galveston region. The report contains regional-scale maps depicting approximate 2016 water-level altitudes (represented by measurements made during December 2015–March 2016) for the Chicot, Evangeline, and Jasper aquifers; maps depicting 1-year (2015–16) water-level changes for each aquifer; maps depicting approximate contoured 5-year (2011–16) water-level changes for each aquifer; maps depicting approximate contoured long-term (1990–2016 and 1977–2016) water-level changes for the Chicot and Evangeline aquifers; a map depicting approximate contoured long-term (2000–16) water-level changes for the Jasper aquifer; a map depicting locations of borehole-extensometer sites; and graphs depicting measured long-term cumulative compaction of subsurface sediments at the extensometers during 1973–2015. Tables listing the water-level data used to construct each water-level map for each aquifer and the measured long-term cumulative compaction data for each extensometer site are included. Graphs depicting water-level measurement data also are included; these graphs can be used to approximate

  5. Water-level altitudes 2017 and water-level changes in the Chicot, Evangeline, and Jasper Aquifers and compaction 1973–2016 in the Chicot and Evangeline Aquifers, Houston-Galveston region, Texas

    Science.gov (United States)

    Kasmarek, Mark C.; Ramage, Jason K.

    2017-08-16

    Most of the land-surface subsidence in the Houston-Galveston region, Texas, has occurred as a direct result of groundwater withdrawals for municipal supply, commercial and industrial use, and irrigation that depressured and dewatered the Chicot and Evangeline aquifers, thereby causing compaction of the aquifer sediments, mostly in the fine-grained silt and clay layers. This report, prepared by the U.S. Geological Survey in cooperation with the Harris-Galveston Subsidence District, City of Houston, Fort Bend Subsidence District, Lone Star Groundwater Conservation District, and Brazoria County Groundwater Conservation District, is one in an annual series of reports depicting water-level altitudes and water-level changes in the Chicot, Evangeline, and Jasper aquifers and measured cumulative compaction of subsurface sediments in the Chicot and Evangeline aquifers in the Houston-Galveston region. This report contains regional-scale maps depicting approximate 2017 water-level altitudes (represented by measurements made during December 2016 through March 2017) and long-term water-level changes for the Chicot, Evangeline, and Jasper aquifers; a map depicting locations of borehole-extensometer (hereinafter referred to as “extensometer”) sites; and graphs depicting measured long-term cumulative compaction of subsurface sediments at the extensometers during 1973–2016.In 2017, water-level-altitude contours for the Chicot aquifer ranged from 200 feet (ft) below the North American Vertical Datum of 1988 (hereinafter referred to as “datum”) in two localized areas in southwestern and northwestern Harris County to 200 ft above datum in west-central Montgomery County. The largest water-level-altitude decline (120 ft) depicted by the 1977–2017 water-level-change contours for the Chicot aquifer was in northwestern Harris County. A broad area where water-level altitudes declined in the Chicot aquifer extends from northwestern, north-central, and southwestern Harris County

  6. In situ spectroscopic evidence for neptunium(V)-carbonate inner-sphere and outer-sphere ternary surface complexes on hematite surfaces.

    Science.gov (United States)

    Arai, Yuji; Moran, P B; Honeyman, B D; Davis, J A

    2007-06-01

    Np(V) surface speciation on hematite surfaces at pH 7-9 under pC2 = 10(-3.45) atm was investigated using X-ray absorption spectroscopy (XAS). In situ XAS analyses suggest that bis-carbonato inner-sphere and tris-carbonato outer-sphere ternary surface species coexist at the hematite-water interface at pH 7-8.8, and the fraction of outer-sphere species gradually increases from 27 to 54% with increasing pH from 7 to 8.8. The results suggest that the heretofore unknown Np(V)-carbonato ternary surface species may be important in predicting the fate and transport of Np(V) in the subsurface environment down gradient of high-level nuclear waste respositories.

  7. Morphology and orientational behavior of silica-coated spindle-type hematite particles in a magnetic field probed by small-angle X-ray scattering.

    Science.gov (United States)

    Reufer, Mathias; Dietsch, Hervé; Gasser, Urs; Hirt, Ann; Menzel, Andreas; Schurtenberger, Peter

    2010-04-15

    Form factor and magnetic properties of silica-coated spindle-type hematite nanoparticles are determined from SAXS measurements with applied magnetic field and magnetometry measurements. The particle size, polydispersity and porosity are determined using a core-shell model for the form factor. The particles are found to align with their long axis perpendicular to the applied field. The orientational order is determined from the SAXS data and compared to the orientational order obtained from magnetometry. The direct access to both, the orientational order of the particles, and the magnetic moments allow one to determine the magnetic properties of the individual spindle-type hematite particles. We study the influence of the silica coating on the magnetic properties and find a fundamentally different behavior of silica-coated particles. The silica coating reduces the effective magnetic moment of the particles. This effect is enhanced with field strength and can be explained by superparamagnetic relaxation in the highly porous particles.

  8. Spatial and spectral resolution of carbonaceous material from hematite (α-Fe2O3) using multivariate curve resolution-alternating least squares (MCR-ALS) with Raman microspectroscopic mapping: implications for the search for life on Mars.

    Science.gov (United States)

    Smith, Joseph P; Smith, Frank C; Booksh, Karl S

    2017-08-21

    The search for evidence of extant or past life on Mars is a primary objective of both the upcoming Mars 2020 rover (NASA) and ExoMars 2020 rover (ESA/Roscosmos) missions. This search will involve the detection and identification of organic molecules and/or carbonaceous material within the Martian surface environment. For the first time on a mission to Mars, the scientific payload for each rover will include a Raman spectrometer, an instrument well-suited for this search. Hematite (α-Fe 2 O 3 ) is a widespread mineral on the Martian surface. The 2LO Raman band of hematite and the Raman D-band of carbonaceous material show spectral overlap, leading to the potential misidentification of hematite as carbonaceous material. Here we report the ability to spatially and spectrally differentiate carbonaceous material from hematite using multivariate curve resolution-alternating least squares (MCR-ALS) applied to Raman microspectroscopic mapping under both 532 nm and 785 nm excitation. For this study, a sample comprised of hematite, carbonaceous material, and substrate-adhesive epoxy in spatially distinct domains was constructed. Principal component analysis (PCA) reveals that both 532 nm and 785 nm excitation produce representative three-phase systems of hematite, carbonaceous material, and substrate-adhesive epoxy in the analyzed sample. MCR-ALS with Raman microspectroscopic mapping using both 532 nm and 785 nm excitation was able to resolve hematite, carbonaceous material, and substrate-adhesive epoxy by generating spatially-resolved chemical maps and corresponding Raman spectra of these spatially distinct chemical species. Moreover, MCR-ALS applied to the combinatorial data sets of 532 nm and 785 nm excitation, which contain hematite and carbonaceous material within the same locations, was able to resolve hematite, carbonaceous material, and substrate-adhesive epoxy. Using multivariate analysis with Raman microspectroscopic mapping, 785 nm excitation more effectively

  9. Trade-off between Zr Passivation and Sn Doping on Hematite Nanorod Photoanodes for Efficient Solar Water Oxidation: Effects of a ZrO2 Underlayer and FTO Deformation.

    Science.gov (United States)

    Subramanian, Arunprabaharan; Annamalai, Alagappan; Lee, Hyun Hwi; Choi, Sun Hee; Ryu, Jungho; Park, Jung Hee; Jang, Jum Suk

    2016-08-03

    Herein we report the influence of a ZrO2 underlayer on the PEC (photoelectrochemical) behavior of hematite nanorod photoanodes for efficient solar water splitting. Particular attention was given to the cathodic shift in onset potential and photocurrent enhancement. Akaganite (β-FeOOH) nanorods were grown on ZrO2-coated FTO (fluorine-doped tin oxide) substrates. Sintering at 800 °C transformed akaganite to the hematite (α-Fe2O3) phase and induced Sn diffusion into the crystal structure of hematite nanorods from the FTO substrates and surface migration, shallow doping of Zr atoms from the ZrO2 underlayer. The ZrO2 underlayer-treated photoanode showed better water oxidation performance compared to the pristine (α-Fe2O3) photoanode. A cathodic shift in the onset potential and photocurrent enhancement was achieved by surface passivation and shallow doping of Zr from the ZrO2 underlayer, along with Sn doping from the FTO substrate to the crystal lattice of hematite nanorods. The Zr based hematite nanorod photoanode achieved 1 mA/cm(2) at 1.23 VRHE with a low turn-on voltage of 0.80 VRHE. Sn doping and Zr passivation, as well as shallow doping, were confirmed by XPS, Iph, and M-S plot analyses. Electrochemical impedance spectroscopy revealed that the presence of a ZrO2 underlayer decreased the deformation of FTO substrate, improved electron transfer at the hematite/FTO interface and increased charge-transfer resistance at the electrolyte/hematite interface. This is the first systematic investigation of the effects of Zr passivation, shallow doping, and Sn doping on hematite nanorod photoanodes through application of a ZrO2 underlayer on the FTO substrate.

  10. Preparation and structural, optical, magnetic, and electrical characterization of Mn{sup 2+}/Co{sup 2+}/Cu{sup 2+} doped hematite nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Srikrishna Ramya, S.I., E-mail: ramyaskr@gmail.com; Mahadevan, C.K.

    2014-03-15

    Pure and Mn{sup 2+} / Co{sup 2+} / Cu{sup 2+} doped (1 and 2 at.%) spherical hematite (α-Fe{sub 2}O{sub 3})nanocrystals have been synthesized by a simple solvothermal method using a domestic microwave oven. XRD measurements confirm that all the seven nanocrystals prepared consist of nanocrystalline hematite phase without any other phases. The energy dispersive X-ray and Fourier transform infrared spectral analyses confirm the phase purity of the nanocrystals prepared. TEM analysis shows the average particle sizes within the range 33–51 nm. Optical absorption measurements indicate that all the three dopants enhance the optical transmittance and reflectance. A red shift is observed in the bandgap energy values estimated from optical absorption and reflectance spectra. Results of magnetic measurements made at room temperature using a vibrating sample magnetometer indicate significant changes in the magnetic properties (coercivity, retentivity and saturationmagnetization) due to doping. Results of magnetic measurements indicate significant changes in the magnetic properties. Results of AC electrical measurements made at various temperatures in the range 40–130 °C and frequencies in the range 100 Hz –1 MHz indicate low dielectric constants and AC electrical conductivities and consequently show the occurrence of nanoconfined states. -- Graphical abstract: The indexed X-ray diffraction (XRD) patterns of all the seven nanocrystals indicate the rhombohedral structure of hematite (JCPDS card No.13-0534). No impurity phase like oxides of Mn or Co or Cu was detected above equipment limit. The average crystallite (grain) sizes estimated using the Scherrer's formula. Highlights: • Pure and Mn/Co/Cu-doped hematite nanocrystals have been prepared. • The method adopted for the preparation is simple, economical and scalable. • Prepared nanocrystals are spherical in shape with good crystallinity and phase purity. • Mn/Co/Cu-doping enhances the optical

  11. Confinement and surface effects on the physical properties of rhombohedral-shape hematite (α-Fe{sub 2}O{sub 3}) nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Luna, Carlos, E-mail: carlos.lunacd@uanl.edu.mx [Universidad Autónoma de Nuevo León (UANL), Av. Universidad S/N, San Nicolás de los Garza, Nuevo León 66455 (Mexico); Cuan-Guerra, Aída D. [Universidad Autónoma de Nuevo León (UANL), Av. Universidad S/N, San Nicolás de los Garza, Nuevo León 66455 (Mexico); Barriga-Castro, Enrique D. [Centro de Investigación en Química Aplicada (CIQA), Blvd. Enrique Reyna Hermosillo No. 140, Saltillo, 25294 Coahuila (Mexico); Núñez, Nuria O. [Instituto de Ciencia de Materiales de Sevilla (ICMS), CSIC-US, Avda. Americo Vespucio n° 49, Isla de la Cartuja, 41092 Sevilla (Spain); Mendoza-Reséndez, Raquel [Universidad Autónoma de Nuevo León (UANL), Av. Universidad S/N, San Nicolás de los Garza, Nuevo León 66455 (Mexico)

    2016-08-15

    Highlights: • Uniform rhombohedral hematite nanocrystals (RHNCs) have been obtained. • A detailed formation mechanism of these HNCS has been proposed. • Phonon confinement effects were revealed in the RHNCS vibrational bands. • Quantum confinement effects on the optical and electronic properties were found. - Abstract: Morphological, microstructural and vibrational properties of hematite (α-Fe{sub 2}O{sub 3}) nanocrystals with a rhombohedral shape and rounded edges, obtained by forced hydrolysis of iron(III) solutions under a fast nucleation, have been investigated in detail as a function of aging time. These studies allowed us to propose a detailed formation mechanism and revealed that these nanocrystals are composed of four {104} side facets, two {110} faces at the edges of the long diagonal of the nanocrystals and two {−441} facets as the top and bottom faces. Also, the presence of nanoscopic pores and fissures was evidenced. The vibrational bands of such nanocrystals were shifted to lower frequencies in comparison with bulk hematite ones as the nanocrystal size was reduced due to phonon confinement effects. Also, the indirect and direct transition band gaps displayed interesting dependences on the aging time arising from quantum confinement and surface effects.

  12. Production and characterization of submicron hematite (α−Fe{sub 2}O{sub 3}) particles by ultrasonic spray pyrolysis method

    Energy Technology Data Exchange (ETDEWEB)

    Kırcı, Burak; Ebin, Burçak; Gürmen, Sebahattin [Department of Metallurgical and Materials Engineering, Istanbul Technical University Istanbul (Turkey)

    2013-12-16

    The ultrasonic spray pyrolysis (USP) method has been used to prepare submicron hematite (α−Fe{sub 2}O{sub 3}) particles using two different industrial pickling solutions of iron chloride (41 g/L FeCl{sub 2} and 54 g/L FeCl{sub 3}) Particles were obtained by thermal decomposition of generated aerosols from precursor solutions using 1.7 MHz ultrasonic atomizer. Reaction temperature was set up at 800 °C and aerosol droplets were carried into the heated zone by 0.7 L/min air flow rate. X-Ray Diffraction (XRD) studies were used to determine the crystal structure and crystallite size of the particles. Results indicate that patterns correspond to hematite phase with rhombohedral crystal structure (space group: R3c). The crystallite sizes of particles prepared from FeCl{sub 2} and FeCl{sub 3} solutions that were calculated from Scherrer equation are 59 and 33 nm, respectively. Scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) investigations give detailed information about particle size, morphology and composition. SEM micrographs show that hematite nanoparticles aggregate and formed spherical secondary particles in submicron range.

  13. Facile conversion of bulk metal surface to metal oxide single-crystalline nanostructures by microwave irradiation: Formation of pure or Cr-doped hematite nanostructure arrays

    International Nuclear Information System (INIS)

    Cho, Seungho; Jeong, Haeyoon; Lee, Kun-Hong

    2010-01-01

    We report a method for converting the surfaces of bulk metal substrates (pure iron or stainless steel) to metal oxide (hematite or Cr-doped hematite) nanostructures using microwave irradiation. When microwave radiation (2.45 GHz, single-mode) was applied to a metal substrate under the flow of a gas mixture containing O 2 and Ar, metal oxide nanostructures formed and entirely covered the substrate. The nanostructures were single crystalline, and the atomic ratios of the substrate metals were preserved in the nanostructures. When a pure iron sheet was used as a substrate, hematite nanowires (1000 W microwave radiation) or nanosheets (1800 W microwave radiation) formed on the surface of the substrate. When a SUS410 sheet was used as a substrate, slightly curved rod-like nanostructures were synthesized. The oxidation states of Fe and Cr in these nanorods were Fe 3+ and Cr 3+ . Quantitative analyses revealed an average Fe/Cr atomic ratio of 9.2, nearly identical to the ratio of the metals in the SUS410 substrate.

  14. Hematite photoanode co-functionalized with self-assembling melanin and C-phycocyanin for solar water splitting at neutral pH

    Energy Technology Data Exchange (ETDEWEB)

    Schrantz, Krisztina; Wyss, Pradeep P.; Ihssen, Julian; Toth, Rita; Bora, Debajeet K.; Vitol, Elina A.; Rozhkova, Elena A.; Pieles, Uwe; Thöny-Meyer, Linda; Braun, Artur

    2017-04-01

    tNature provides functional units which can be integrated in inorganic solar cell materials, such as lightharvesting antenna proteins and photosynthetic molecular machineries, and thus help in advancing artifi-cial photosynthesis. Their integration needs to address mechanical adhesion, light capture, charge transferand corrosion resistance. We showed recently how enzymatic polymerization of melanin can immobi-lize the cyanobacterial light harvesting protein C-phycocyanin on the surface of hematite, a prospectivemetal oxide photoanode for solar hydrogen production by water splitting in photoelectrochemical cells.After the optimization of the functionalization procedure, in this work we show reproducible hydrogenproduction, measured parallel to the photocurrent on this bio-hybrid electrode in benign neutral pHphosphate. Over 90% increase compared to the photocurrent of the pristine hematite could be achieved.The hydrogen evolution was monitored during the photoelectrochemical measurement in an improvedphotoelectrochemical cell. The C-phycocyanin-melanin coating on the hematite was shown to exhibit acomb-like fractal pattern. Raman spectroscopy supported the presence of the protein on the hematiteanode surface. The stability of the protein coating is demonstrated during the 2 h GC measurement andthe 24 h operando current density measurement

  15. Intensification of the Reverse Cationic Flotation of Hematite Ores with Optimization of Process and Hydrodynamic Parameters of Flotation Cell

    Science.gov (United States)

    Poperechnikova, O. Yu; Filippov, L. O.; Shumskaya, E. N.; Filippova, I. V.

    2017-07-01

    The demand of high grade iron ore concentrates is a major issue due to the depletion of rich iron-bearing ores and high competitiveness in the iron ore market. Iron ore production is forced out to upgrade flowsheets to decrease the silica content in the pelettes. Different types of ore have different mineral composition and texture-structural features which require different mineral processing methods and technologies. The paper presents a comparative study of the cationic and anionic flotation routes to process a fine-grain oxidized iron ore. The modified carboxymethyl cellulose was found as the most efficient depressant in reverse cationic flotation. The results of flotation optimization of hematite ores using matrix of second-order center rotatable uniform design allowed to define the collector concentration, impeller rotation speed and air flowrate as the main flotation parameters impacting on the iron ore concentrate quality and iron recovery in a laboratory flotation machine. These parameters have been selected as independent during the experiments.

  16. An ab initio model of electron transport in hematite (a-Fe2O3) basal planes

    International Nuclear Information System (INIS)

    Rosso, Kevin M.; Smith, Dayle MA; Dupuis, Michel

    2003-01-01

    Transport of conduction electrons through basal planes of the hematite lattice was modeled as a valence alternation of iron cations using ab initio molecular orbital calculations and electron transfer theory. A cluster approach was successfully implemented to compute electron transfer rate-controlling quantities such as the reorganization energy and electronic coupling matrix element. Localization of a conduction electron at an iron lattice site is accompanied by large iron/oxygen bond length increases that give rise to a large inner-sphere component of the reorganization energy. The interaction between the reactant and product electronic states in the crossing?point configuration is substantial and leads to an adiabatic electron transfer system. Electron transfer is predicted to possess a small positive activation energy that turns out to be in excellent agreement with values deduced from conductivity measurements. Measured electron mobility can be explained in terms of nearest neighbor electron hops without significant contribution from iron atoms further away. Comparison of the predicted maximum polaron binding energy with the predicted half bandwidth indicates compliance with the small polaron condition. Therefore the localized electron treatment is appropriate to describe electron transport in this system

  17. Two-Step Hydrothermal Synthesis of Bifunctional Hematite-Silver Heterodimer Nanoparticles for Potential Antibacterial and Anticancer Applications

    Science.gov (United States)

    Trang, Vu Thi; Tam, Le Thi; Phan, Vu Ngoc; Van Quy, Nguyen; Huy, Tran Quang; Le, Anh-Tuan

    2017-06-01

    In recent years, the development of composite nanostructures containing noble metal and magnetic nanocrystals has attracted much interest because they offer a promising avenue for multifunctional applications in nanomedicine and pharmacotherapy. In this work, we present a facile two-step hydrothermal approach for the synthesis of bifunctional heterodimer nanoparticles (HDNPs) composed of hematite nanocubes (α-Fe2O3 NCs) and silver nanoparticles (Ag-NPs). The formation and magnetic property of α-Fe2O3-Ag HDNPs was analyzed by transmission electron microscopy, x-ray diffraction and vibrating sample magnetometer. Interestingly, the hydrothermal-synthesized α-Fe2O3-Ag HDNPs were found to display significant antibacterial activity against three types of infectious bacteria. The cytotoxicity of α-Fe2O3-Ag nanocomposite against lung cancer A549 cell line was investigated and compared with that of pure α-Fe2O3 NCs and Ag-NPs. The obtained results reveal that the α-Fe2O3-Ag nanocomposite exhibited higher anticancer performance than that of pure Ag-NPs, whereas pure α-Fe2O3 NCs were not cytotoxic to the tested cells. The inhibitory concentration (IC50) of the α-Fe2O3-Ag nanocomposite was found at 20.94 μg/mL. With the aforementioned properties, α-Fe2O3-Ag HDNPs showed a high potential as a multifunctional material for advanced biomedicine and nanotherapy applications.

  18. A photoelectrochemical (PEC) study on graphene oxide based hematite thin films heterojunction (R-GO/Fe2O3)

    Science.gov (United States)

    Sharma, Poonam; Zachariah, Michael; Ehrman, Sheryl; Shrivastava, Rohit; Dass, Sahab; Satsangi, Vibha; Michael Zachariah, Sheryl Ehrman Collaboration; Rohit Shrivastava, Sahab Dass Collaboration; Vibha R Satsangi, Poonam Sharma Team

    2013-03-01

    Graphene has an excellent electronic conductivity, a high theoretical surface area of 2630 m2/g and excellent mechanical properties and, thus, is a promising component for high-performance electrode materials. Following this, GO has been used to modify the PEC response of photoactive material hematite thin films in PEC cell. A reduced graphene oxide/iron oxide (R-GO/Fe2O3) thin film structure has been successfully prepared on ITO by directly growing iron oxide particles on the thermally reduced graphene oxide sheets prepared from suspension of exfoliated graphene oxide. R-GO/Fe2O3 thin films were tested in PEC cell and offered ten times higher photocurrent density than pristine Fe2O3 thin film sample. XRD, SEM, EDS, UV-Vis, Mott-Schottky and Raman studies were carried out to study spectro-electrochemical properties. Enhanced PEC performance of these photoelectrodes was attributed to its porous morphology, improved conductivity upon favorable carrier transfer across the oxides interface.

  19. Fixing arsenic contained in a gas phase using solid hematite; Fijacion de arsenico en fase gas con hematita solida

    Energy Technology Data Exchange (ETDEWEB)

    Balladares, E.; Gonzalez, A.; Rarra, R.; Sanchez, M.

    2004-07-01

    Feasibility to obtain ferric arsenate starting from arsenic containing gas in contact with Fe{sub 3}O{sub 3} has been studied. Thermodynamic stability of the system Fe-As-O was analysed in order to verify conditions to form Fe{sub x}As{sub y}O{sub z} type compounds. Experiments were made using a hematite sample suspended in a thermogravimetric device. As{sub 4}O{sub 6} was generated starting from solid As{sub 2}O{sub 3} which was circulating through the iron oxide. Final samples were analysed chemically and by means of DRX, verifying the formation of FeAsO{sub 4}, FeAsO{sub 4}.2h{sub 2}O and FeAsO{sub 4}.(H{sub 2}O){sub 2} in small quantities. Tests in porous bed and pellets were carried out, studying the effect of: porosity, temperature and oxygen potential. The largest conversion obtained was 10% at 800 degree centigree, pO{sub 2}=50% and porosity=0.883. (Author) 9 refs.

  20. Spectral and magnetic properties of hematite Fe2O3 (001) surface: results from DFT+DMFT

    Science.gov (United States)

    Kabir, Alamgir; Turkowski, Volodymyr; Rahman, Talat S.

    2015-03-01

    It has been demonstrated that strong correlation effects may significantly modify the spectrum of a system, in particular leading to an increase of the bandgap and to a change in the orbital occupancies, which affects the magnetic properties of the system. With this in mind, we have examined the spectral and magnetic properties of the hematite Fe2O3 film system with (001) surface orientation by using the combined density functional theory (DFT) and dynamical mean-field theory (DMFT) approach. We pay special attention to the surface geometry and electronic structure, magnetization and magnetic anisotropy (MA) of the system by performing calculations at different values of the parameters for the local Coulomb repulsion and exchange energy. To calculate the MA of the system, we propose and apply a combined Bruno model within DMFT, and demonstrate that under-coordinated surface Fe atoms contribute significantly to the MA of the film. We also compare our results with the DFT+U solution and show that the dynamical effects taken into account by the DMFT significantly affect system properties, notably leading to a decrease of the atomic magnetic moments. Work supported in part by DOE Grant No. DOE-DE-FG02-07ER46354.

  1. Surface reactivity of mercury on the oxygen-terminated hematite(0001) surface: a first-principle study

    Science.gov (United States)

    Jung, J. E.; Wilcox, J.

    2016-12-01

    Hematite (α-Fe2O3) is a common mineral found in Earth's near-surface environment. Due to its nontoxicity, corrosion-resistance, and high thermal stability, α-Fe2O3 has attracted attentions as materials for various applications such as photocatalysts, gas sensors, as well as for the removal of heavy metals. In this study, α-Fe2O3 is chosen for potential mercury (Hg) sorbent in order to remove Hg from coal-fired power plants. Specifically, theoretical approaches using density functional theory (DFT) is used to understand surface reactivity of Hg on oxygen (O) terminated α-Fe2O3(0001) surface. The most probable adsorption sites of Hg, chlorine (Cl), and mercury chloride (HgCl) on the α-Fe2O3 surface are found based on adsorption energy calculations, and the oxidation states of the adsorbates are determined by Bader charge analysis. Additionally, projected density of states (PDOS) analysis characterizes the surface-adsorbate bonding mechanism. The results of adsorption energy calculation proposes that Hg physisorbs to the α-Fe2O3(0001) surface with adsorption energy of -0.278 eV, and the subsequent Bader charge analysis confirms that Hg is slightly oxidized. In addition, Cl introduced to the Hg-adsorbed surface strengthens Hg stability on the α-Fe2O3(0001) surface as evidenced by a shortened Hg-surface equilibrium distance. The PDOS analysis also suggests that Cl enhances the chemical bonding between the surface and the adsorbate, thereby increasing adsorption strength. In summary, α-Fe2O3 has ability to adsorb and oxidize Hg, and this reactivity is enhanced in the presence of Cl.

  2. Colour and toxic characteristics of metakaolinite-hematite pigment for integrally coloured concrete, prepared from iron oxide recovered from a water treatment plant of an abandoned coal mine

    Science.gov (United States)

    Sadasivam, Sivachidambaram; Thomas, Hywel Rhys

    2016-07-01

    A metakaolinite-hematite (KH) red pigment was prepared using an ocherous iron oxide sludge recovered from a water treatment plant of an abandoned coal mine. The KH pigment was prepared by heating the kaolinite and the iron oxide sludge at kaolinite's dehydroxylation temperature. Both the raw sludge and the KH specimen were characterised for their colour properties and toxic characteristics. The KH specimen could serve as a pigment for integrally coloured concrete and offers a potential use for the large volumes of the iron oxide sludge collected from mine water treatment plants.

  3. Magnetic properties of nano-scale hematite, α-Fe{sub 2}O{sub 3}, studied by time-of-flight inelastic neutron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hill, Adrian H. [The European Synchrotron Radiation Facility, 6 rue Jules Horowitz, BP220, 38043 Grenoble Cedex 9 (France); Jacobsen, Henrik, E-mail: hjacobse@fys.ku.dk; Holm, Sonja L.; Lefmann, Kim [Nanoscience Centre, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen (Denmark); Stewart, J. Ross [Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot OX11 OQX (United Kingdom); Jiao, Feng [Department of Chemical Engineering, University of Delaware, Center for Catalytic Science and Technology, 150 Academy Street, Newark, Delaware 19716-3110 (United States); Jensen, Niels P. [Department of Energy Conversion and Storage, Technical University of Denmark, Frederiksborgvej 399, DK-4000 Roskilde (Denmark); Mutka, Hannu; Seydel, Tilo [The Institute Laue-Langevin, 6 rue Jules Horowitz, BP156, 38042 Grenoble Cedex 9 (France); Harrison, Andrew [The Institute Laue-Langevin, 6 rue Jules Horowitz, BP156, 38042 Grenoble Cedex 9 (France); EaStCHEM, School of Chemistry and Centre for Science at Extreme Conditions, The King' s Buildings, The University of Edinburgh, Mayfield Road, Edinburgh EH9 3JZ (United Kingdom)

    2014-01-28

    Samples of nanoscale hematite, α-Fe{sub 2}O{sub 3}, with different surface geometries and properties have been studied with inelastic time-of-flight neutron scattering. The 15 nm diameter nanoparticles previously shown to have two collective magnetic excitation modes in separate triple-axis neutron scattering studies have been studied in further detail using the advantage of a large detector area, high resolution, and large energy transfer range of the IN5 TOF spectrometer. A mesoporous hematite sample has also been studied, showing similarities to that of the nanoparticle sample and bulk α-Fe{sub 2}O{sub 3}. Analysis of these modes provides temperature dependence of the magnetic anisotropy coefficient along the c-axis, κ{sub 1}. This is shown to remain negative throughout the temperature range studied in both samples, providing an explanation for the previously observed suppression of the Morin transition in the mesoporous material. The values of this anisotropy coefficient are found to lie between those of bulk and nano-particulate samples, showing the hybrid nature of the mesoporous 3-dimensional structure.

  4. Regional sulfate-hematite-sulfide zoning in the auriferous Mariana anticline, Quadrilátero Ferrífero of Minas Gerais, Brazil

    Science.gov (United States)

    Cabral, Alexandre Raphael; Koglin, Nikola; Strauss, Harald; Brätz, Helene; Kwitko-Ribeiro, Rogerio

    2013-10-01

    The distribution of mineral deposits, characterised as barite deposits, hematite-rich auriferous deposits and auriferous tourmaline-sulfide deposits, displays a regional sulfate-hematite-sulfide zoning along the thrust-delineated limbs of the Mariana anticline, in the south-eastern part of the Quadrilátero Ferrífero of Minas Gerais, Brazil. Cross-cut relationships of barite veins and sulfide lodes indicate that sulfidation occurred in a late-tectonic context, which is here attributed to the collapse of the ˜0.6-Ga Brasiliano thrust front. Reconnaissance S-isotopic data from barite and pyrite (Antônio Pereira barite deposit and its adjacent gold deposit, respectively), and arsenopyrite (Passagem de Mariana gold deposit), suggest a new interpretation for the hydrothermal fluid overprint in the Mariana anticline. The Antônio Pereira barite has Δ33S values that are near zero, constraining the sulfate source to rocks younger than 2.45 Ga. The barite-δ34S values are between +19.6 and +20.8 ‰. The Passagem arsenopyrite and tourmaline have Co/Ni ratios that define a positive linear trend with the Antônio Pereira pyrite. The latter has homogenous δ34S values, between +8.8 and +8.9 ‰, which are compatible with thermochemical reduction of aqueous sulfate with the S-isotopic composition of the Antônio Pereira barite.

  5. Rapid synthesis and optical properties of hematite ({alpha}-Fe{sub 2}O{sub 3}) nanostructures using a simple thermal decomposition method

    Energy Technology Data Exchange (ETDEWEB)

    Al-Gaashani, R., E-mail: Rashad_jashani@yahoo.com [School of Applied Physics, Faculty Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Department of Physics, Thamar University, Dhamar, Republic of Yemen (Yemen); Radiman, S. [School of Applied Physics, Faculty Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Tabet, N. [Department of Physics and Center of Research Excellence in Renewable Energy, King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Daud, A.R. [School of Applied Physics, Faculty Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia)

    2013-02-15

    Highlights: Black-Right-Pointing-Pointer A novel method for the synthesis of hematite nanopowder is reported. Black-Right-Pointing-Pointer The morphology of {alpha}-Fe{sub 2}O{sub 3} changed with altering the preparation temperature. Black-Right-Pointing-Pointer The coral like nano {alpha}-Fe{sub 2}O{sub 3} prepared at 500 and 600 Degree-Sign C showed novel optical behavior. Black-Right-Pointing-Pointer The coral like nano {alpha}-Fe{sub 2}O{sub 3} could be used to enhance efficiency of the solar cells. - Abstract: Hematite nanostructures were prepared by a simple technique using the thermal decomposition of iron (III) nitrate 9-hydrate at different temperatures under air atmosphere. Observations using field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) showed that the morphology of the nanostructures changed as the temperature was varied while their size increased with increasing preparation time. Samples prepared at 300, 400, and 500 Degree-Sign C were made of particles with a quantum dots (QDs) size. X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) confirmed that the as-synthesized powders are pure {alpha}-Fe{sub 2}O{sub 3}. The optical energy gap of the samples varied from 3.2 eV to 2.7 eV as the preparation temperature increased from 300 Degree-Sign C to 600 Degree-Sign C.

  6. Coating a polystyrene well-plate surface with synthetic hematite, goethite and aluminium hydroxide for cell mineral adhesion studies in a controlled environment

    International Nuclear Information System (INIS)

    Pouran, Hamid M.; Banwart, Steve A.; Romero-Gonzalez, Maria

    2014-01-01

    Highlights: • Hematite, goethite and aluminium hydroxide were synthesized and characterize. • Polystyrene cell culture well plates were coated with the synthetic metal oxides. • The coated well plates proven to be completely identical to the synthetic minerals. • The coating method is compatible with what occurs in aquifers with metal oxides. • This method provides a key experimental part for cell mineral adhesion studies. - Abstract: Iron and aluminium oxides are available in many climatic regions and play a vital role in many environmental processes, including the interactions of microorganisms in contaminated soils and groundwater with their ambient environment. Indigenous microorganisms in contaminated environments often have the ability to degrade or transform those contaminants, a concept that supports an in situ remediation approach and uses natural microbial populations in order to bio-remediate polluted sites. These metal oxides have a relatively high pH-dependent surface charge, which makes them good candidates for studying mineral–bacterial adhesion. Given the importance of understanding the reactions that occur at metal oxide and bacterial cell interfaces and to investigate this phenomenon further under well-characterized conditions, some of the most common iron and aluminium oxides; hematite, goethite and aluminium hydroxide, were synthesized and characterized and a coating method was developed to coat polystyrene well-plates as a surface exposable to bacterial adhesion with these minerals (non-treated polystyrene-12 well-plates which are used for cell cultures). The coating process was designed in a way that resembles naturally coated surfaces in aquifers. Hematite, Fe 2 O 3 , was synthesized from acidic FeCl 3 solution, while goethite, FeOOH, and aluminium hydroxide, Al(OH) 3 , were prepared from an alkaline solution of Fe(NO 3 ) 3 and Al(NO 3 ) 3 . They were further characterized using X-ray diffraction (XRD), Fourier transform infrared

  7. Synthesis, morphology and microstructure of pomegranate-like hematite ({alpha}-Fe{sub 2}O{sub 3}) superstructure with high coercivity

    Energy Technology Data Exchange (ETDEWEB)

    Tadic, Marin, E-mail: marint@vinca.rs [Condensed Matter Physics Laboratory, Vinca Institute, University of Belgrade, P.O. Box 522, 11001 Belgrade (Serbia); Citakovic, Nada [Military Academy, Generala Pavla Jurisica Sturma 33, University of Belgrade, 11000 Belgrade (Serbia); Panjan, Matjaz [Jozef Stefan Institute, Jamova 39, 1000 Ljubljana (Slovenia); Stanojevic, Boban [Vinca Institute of Nuclear Sciences, P.O. Box 522, 11001 Belgrade, University of Belgrade (Serbia); Markovic, Dragana [Condensed Matter Physics Laboratory, Vinca Institute, University of Belgrade, P.O. Box 522, 11001 Belgrade (Serbia); Jovanovic, Dorde [Center for Solid State Physics and New Materials, Institute of Physics, University of Belgrade, Pregrevica 118, 11080 Belgrade (Serbia); Spasojevic, Vojislav [Condensed Matter Physics Laboratory, Vinca Institute, University of Belgrade, P.O. Box 522, 11001 Belgrade (Serbia)

    2012-12-05

    Highlights: Black-Right-Pointing-Pointer We found superior magnetic properties of the hematite ({alpha}-Fe{sub 2}O{sub 3}). Black-Right-Pointing-Pointer TEM and HRTEM images show a pomegranate-like superstructure. Black-Right-Pointing-Pointer Magnetic measurements display high coercivity H{sub C} = 4350 Oe at the room temperature. - Abstract: We found novel and superior magnetic properties of the hematite ({alpha}-Fe{sub 2}O{sub 3}) that originate from an internal microstructure of particles and strong inter-particle interactions between nanocrystal sub-units. The hematite particles were synthesized by thermal decomposition of iron (III) nitrate without any template or surfactant. The purity, size, crystallinity, morphology, microstructure and magnetic features of the as-prepared particles were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), Raman spectroscopy (RS) and SQUID magnetometry. An XRD study reveals a pure phase of {alpha}-Fe{sub 2}O{sub 3} whereas TEM shows {alpha}-Fe{sub 2}O{sub 3} spheres with a diameter of about 150 nm. RS also shows high quality and purity of the sample. Moreover, TEM and HRTEM images show a pomegranate-like superstructure and evidence that the spherical particles are composed of individual well-crystallized nanoparticle sub-units (self-assembled nanoparticles) with a size of about 20 nm. Magnetic measurements display hysteretic behavior at the room temperature with remanent magnetization M{sub r} = 0.731 emu/g, saturation magnetization M{sub S} = 6.83 emu/g and coercivity H{sub C} = 4350 Oe, as well as the Morin transition at T{sub M} = 261 K. These results and comparison with those in the literature reveal that the sample has extremely high coercivity. The magnetic properties of the sample are discussed in relation to morphology, internal microstructure, surface

  8. Comparative study of the shield of concrete blocks with hematite in relation to common concrete blocks; Avaliacao comparativa entre as propriedades de atenuacao de blocos de concreto com hematita e blocos de concreto convencional

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Paulo R.; Buerger, Andre A., E-mail: pcosta@if.usp.br [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Inst. de Fisica. Lab. de Dosimetria; Naccache, Veronica K.; Priszkulnik, Simao [Universidade Mackenzie, Sao Paulo, SP (Brazil). Departamento de Engenharia

    2012-08-15

    The present work shows results of an empirical evaluation of the transmission properties of two radioprotection materials: an ordinary concrete and an ordinary concrete mixed with hematite. It was used techniques of x-ray spectroscopy and measurements of the air-kerma transmitted through these two materials in order to compare the transmission properties for each one. (author)

  9. Stable High-Capacity Lithium Ion Battery Anodes Produced by Supersonic Spray Deposition of Hematite Nanoparticles and Self-Healing Reduced Graphene Oxide

    International Nuclear Information System (INIS)

    Lee, Jong-Gun; Joshi, Bhavana N.; Lee, Jong-Hyuk; Kim, Tae-Gun; Kim, Do-Yeon; Al-Deyab, Salem S.; Seong, Il Won; Swihart, Mark T.; Yoon, Woo Young; Yoon, Sam S.

    2017-01-01

    Hematite (Fe 2 O 3 ) nanoparticles and reduced graphene oxide (rGO) were supersonically sprayed onto copper current collectors to create high-performance, binder-free lithium ion battery (LIB) electrodes. Supersonic spray deposition is rapid, low-cost, and suitable for large-scale production. Supersonic impact of rGO sheets and Fe 2 O 3 nanoparticles on the substrate produces compacted nanocomposite films with short diffusion lengths for Li + ions. This structure produces high reversible capacity and markedly improved capacity retention over many cycles. Decomposition of lithium oxide generated during cycling activates the solid electrolyte interface layer, contributing to high capacity retention. The optimal composition ratio of rGO to Fe 2 O 3 was 9.1 wt.%, which produced a reversible capacity of 1242 mAh g −1 after N = 305 cycles at a current density of 1000 mA g −1 (1C).

  10. Comparison of the mineralogical effects of an experimental forest fire on a goethite/ferrihydrite soil with a topsoil that contains hematite, maghemite and goethite

    DEFF Research Database (Denmark)

    Nørnberg, Per; Vendelboe, Anders Lindblad; Gunnlaugsson, Haraldur Pall

    2009-01-01

    as the result of high temperature as found after forest fires. However, a body of evidence argues against these sites having been exposed to fire. In an attempt to get closer to an explanation of this Fe mineralogy, an experimental forest fire was produced. The results showed a clear mineralogical zonation down...... to 10 cm depth. This was not observed at the natural sites, which contained a mixture of goethite/ferrihydrite, hematite and maghemite down to 20 cm depth. The experimental forest fire left charcoal and ashes at the topsoil, produced high pH and decreased organic matter content, all of which...... is in contrast to the natural sites. The conclusion from this work is that the mineralogy of these sites is not consistent with exposure to forest fire, but may instead result from long-term transformation in a reducing environment, possibly involving microbiology....

  11. DCS Terrain for Jasper County, GA

    Data.gov (United States)

    Federal Emergency Management Agency, Department of Homeland Security — Terrain data, as defined in FEMA Guidelines and Specifications, Appendix M: Data Capture Standards, describes the digital topographic data that was used to create...

  12. DCS Hydraulics Submission for Jasper County, GA

    Data.gov (United States)

    Federal Emergency Management Agency, Department of Homeland Security — Recent developments in digital terrain and geospatial database management technology make it possible to protect this investment for existing and future projects to...

  13. Exit! Schmollis! Fiduzit! / Jasper von Altenbockum

    Index Scriptorium Estoniae

    Altenbockum, Jasper von

    2008-01-01

    Göttingenis toimus baltisaksa ja balti üliõpilasõpilasorganisatsioonide kohtumine "Völkerkommers". Eesti president Toomas Hendrik Ilves ütles iseseisvuspäeval kahe aasta eest, et iseseisvuse taastamine 1991. aastal oleks olnud mõeldamatu ilma akadeemiliste organisatsioonide tegevuseta

  14. Kinetics of the reduction of hematite (Fe{sub 2}O{sub 3}) by methane (CH{sub 4}) during chemical looping combustion: A global mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Monazam, Esmail R; Breault, Ronald W; Siriwardane, Ranjani; Richards, George; Carpenter, Stephen

    2013-10-01

    Chemical-looping combustion (CLC) has emerged as a promising technology for fossil fuel combustion which produces a sequestration ready concentrated CO{sub 2} stream in power production. A CLC system is composed with two reactors, an air and a fuel reactor. An oxygen carrier such as hematite (94%Fe{sub 2}O{sub 3}) circulates between the reactors, which transfers the oxygen necessary for the fuel combustion from the air to the fuel. An important issue for the CLC process is the selection of metal oxide as oxygen carrier, since it must retain its reactivity through many cycles. The primary objective of this work is to develop a global mechanism with respective kinetics rate parameters such that CFD simulations can be performed for large systems. In this study, thermogravimetric analysis (TGA) of the reduction of hematite (Fe{sub 2}O{sub 3}) in a continuous stream of CH{sub 4} (15, 20, and 35%) was conducted at temperatures ranging from 700 to 825{degrees}C over ten reduction cycles. The mass spectroscopy analysis of product gas indicated the presence of CO{sub 2} and H{sub 2}O at the early stage of reaction and H{sub 2} and CO at the final stage of reactions. A kinetic model based on two parallel reactions, 1) first-order irreversible rate kinetics and 2) Avrami equation describing nucleation and growth processes, was applied to the reduction data. It was found, that the reaction rates for both reactions increase with, both, temperature and the methane concentration in inlet gas.

  15. CO adsorption on small Au{sub n} (n = 1–4) structures supported on hematite. I. Adsorption on iron terminated α-Fe{sub 2}O{sub 3} (0001) surface

    Energy Technology Data Exchange (ETDEWEB)

    Pabisiak, Tomasz; Kiejna, Adam, E-mail: kiejna@ifd.uni.wroc.pl [Institute of Experimental Physics, University of Wrocław, Plac M. Borna 9, 50-204 Wrocław (Poland); Winiarski, Maciej J. [Institute of Experimental Physics, University of Wrocław, Plac M. Borna 9, 50-204 Wrocław (Poland); Institute of Low Temperature and Structure Research, Polish Academy of Sciences, ul. Okólna 2, 50-422 Wrocław (Poland)

    2016-01-28

    This is the first of two papers dealing with the adsorption of Au and formation of Au{sub n} nanostructures (n = 1–4) on hematite (0001) surface and adsorption of CO thereon. The stoichiometric Fe-terminated (0001) surface of hematite was investigated using density functional theory in the generalized gradient approximation of Perdew-Burke-Ernzerhof (PBE) form with Hubbard correction U, accounting for strong electron correlations (PBE+U). The structural, energetic, and electronic properties of the systems studied were examined for vertical and flattened configurations of Au{sub n} nanostructures adsorbed on the hematite surfaces. The flattened ones, which can be viewed as bilayer-like structures, were found energetically more favored than vertical ones. For both classes of structures the adsorption binding energy increases with the number of Au atoms in a structure. The adsorption of Au{sub n} induces charge rearrangement at the Au{sub n}/oxide contact which is reflected in work function changes. In most considered cases Au{sub n} adsorption increases the work function. A detailed analysis of the bonding electron charge is presented and the corresponding electron charge rearrangements at the contacts were quantified by a Bader charge analyses. The interaction of a CO molecule with the Au{sub n} nanostructures supported on α-Fe{sub 2}O{sub 3} (0001) and the oxide support was studied. It is found that the CO adsorption binding to the hematite supported Au{sub n} structures is more than twice as strong as to the bare hematite surface. Analysis of the Bader charges on the atoms showed that in each case CO binds to the most positively charged (cationic) atom of the Au{sub n} structure. Changes in the electronic structure of the Au{sub n} species and of the oxide support, and their consequences for the interactions with CO, are discussed.

  16. Fluoride ions sorption of the water using natural and modified hematite with aluminium hydroxide; Sorcion de iones fluoruro del agua utilizando hematita natural y hematita acondicionada con hidroxido de aluminio

    Energy Technology Data Exchange (ETDEWEB)

    Teutli S, E. A.

    2011-07-01

    Fluorine is a mineral known for its dental benefits, but fluoride ions can cause fluoro sis in excessive quantities. There are many epidemiological studies on possible adverse effects resulting from prolonged ingestion of fluoride through drinking water. These studies demonstrate that fluoride mainly affects the bone tissue (bones and teeth), may produce an adverse effect on tooth enamel and can cause mild dental fluoro sis at concentrations from 0.9 to 1.2 mg/L in drinking water. In several states of Mexico, water contaminated with fluoride ions can be found, such as Aguascalientes, Chihuahua, Coahuila, Durango, Guanajuato, Sonora, Zacatecas, San Luis Potosi and Jalisco, where the fluoride ions levels are higher than 1.5 mg/L, established by the Mexican Official Standard (NOM-127-Ssa-2000) which sets the permissible limits of water for human use and consumption. Currently, several technologies have been proposed to remove fluoride ions from water such as precipitation methods which are based on the addition of chemicals to water and sorption methods to removed fluoride ions by sorption or ion exchange reactions by some suitable substrate capable of regenerate and reuse. In this work, the sorption of fluoride ions using unmodified and modified hematite with aluminum hydroxide to remove fluoride ions from water by bath experiments was studied. The hematite was modified by treating it with aluminum hydroxide, NaOH and Al{sub 2}(SO{sub 4}){sub 3} solutions. The characterization of hematite before and after modification with aluminum hydroxide was studied by X-ray diffraction, scanning electron microscopy, EDS and Bet. The effect of ph, contact time, concentration of fluoride ions, and the dose of sorbent on the sorption of fluoride ions by the modified hematite were studied. Equilibrium was reached within 48 hours of contact time and the maximum sorption of fluoride ions were in the range pH{sub eq} between 2.3 and 6.2. Sorption capacities of fluoride ions as a

  17. Study on Reduction Kinetics of Briquettes of Hematite Fines with Boiler Grade Coal and Coke Dust in Two Different Forms: Intermixing and Multilayered

    Science.gov (United States)

    Roy, Gopal Ghosh; Sarkar, Bitan Kumar; Chaudhuri, Mahua Ghosh; Mitra, Manoj Kumar; Dey, Rajib

    2017-10-01

    An attempt has been made to utilise hematite ore fines in the form of briquettes with two different form of mixing i.e. intermixing and multilayered by means of carbothermal reduction along with boiler grade coal and coke dust. The influence of reduction temperature (1323, 1373 and 1423 K) and reduction time (10, 20, 30, 45 and 60 min) has been investigated in detail and the reduced briquettes are characterised by XRD, SEM analyses. The reducibility of intermixing briquettes is found to be higher for multilayered briquettes. In addition, isothermal kinetic study has also been carried out for both intermixing and multilayered briquettes. The activation energy for intermixing briquettes are evaluated to be 125.88 kJ/mol for the initial stage of reaction (CG3 controlled mechanism) and 113.11 kJ/mol for the later part of reaction (D3 controlled mechanism), respectively. In case of multilayered briquettes, the corresponding activation energy is found to be 235.59 kJ/mol for reaction (CG3 controlled mechanism). These results corroborate the observed better reducibility of the intermixing briquettes over multilayered briquettes.

  18. Evaluation of the bleaching flux in clays containing hematite and different clay minerals; Avaliacao do fundente descolorante em argilas contendo hematita e diferentes argilominerais

    Energy Technology Data Exchange (ETDEWEB)

    Silva Junior, E.M.; Lusa, T.; Silva, T.M.; Medeiros, B.B.; Santos, G.R. dos [Universidade Tecnologica Federal do Parana (DAMEC/UFTPR), Pato Branco, PR (Brazil); Morelli, M.R., E-mail: geocrisr@utfpr.edu.com, E-mail: morelli@power.ufscar.br [Universidade Federal de Sao Carlos (DEMa/PPGCEM/UFSCar), SP (Brazil)

    2016-07-01

    Previous studies have shown that the addition of a synthetic flux in a clay mineral constituted by illite phase in the presence of iron oxide with the hematite, promotes color change of the firing products, making the reddish color firing into whiteness. This flow is constituted of a vitreous phase of the silicates family obtained by fusion/solidification of oxides and carbonates. Thus, the objective of this work was that of studying the interaction of the iron element in the final color mechanism of the different types of mineral crystal phase of the clays. In order to study the phenomenon, we obtained different compositions between the select clays and the synthetic flow, and characterization using X-ray diffraction (XRD) and visual analysis. The results showed that the action of the synthetic flow as a modifying agent for color depends on the mineral crystal phase of the clays. The color firing modification does not occur in the clays content high levels of kaolinite mineral phase. (author)

  19. Evaluation of flow accelerated corrosion by coupled analysis of corrosion and flow dynamics. Relationship of oxide film thickness, hematite/magnetite ratio, ECP and wall thinning rate

    International Nuclear Information System (INIS)

    Uchida, Shunsuke; Naitoh, Masanori; Okada, Hidetoshi; Uehara, Yasushi; Koshizuka, Seiichi

    2011-01-01

    Systematic approaches to evaluate flow accelerated corrosion (FAC) are desired before discussing application of countermeasures for FAC. First, future FAC occurrence should be evaluated to identify locations where a higher possibility of FAC occurrence exists, and then, wall thinning rate at the identified FAC occurrence zone is evaluated to obtain the preparation time for applying countermeasures. Wall thinning rates were calculated with two coupled models: 1.static electrochemical analysis and 2.dynamic oxide layer growth analysis. The anodic current density and the electrochemical corrosion potential (ECP) were calculated with the static electrochemistry model based on an Evans diagram. The ferrous ion release rate, determined by the anodic current density, was applied as input for the dynamic double oxide layer model. Some of the dissolved ferrous ion was removed to the bulk water and others precipitated on the surface as magnetite particles. The thickness of oxide layer was calculated with the dynamic oxide layer growth model and then its value was used as input in the electrochemistry model. It was confirmed that the calculated results (corrosion rate and ECP) based on the coupled models were in good agreement with the measured ones. Higher ECP was essential for preventing FAC rate. Moderated conditions due to lower mass transfer coefficients resulted in thicker oxide layer thickness and then higher ECP, while moderated corrosion conditions due to higher oxidant concentrations resulted in larger hematite/magnetite rate and then higher ECP.

  20. Evaluation of flow accelerated corrosion by coupled analysis of corrosion and flow dynamics (3), relationship of oxide film thickness, hematite/magnetite ratio, ECP and wall thinning rate

    International Nuclear Information System (INIS)

    Uchida, Shunsuke; Naitoh, Masanori; Okada, Hidetoshi; Uehara, Yasushi; Koshizuka, Seiichi

    2009-01-01

    Systematic approaches for evaluating flow accelerated corrosion (FAC) are desired before discussing application of countermeasures for FAC. Firstly, future FAC occurrence should be evaluated to identify locations where a higher possibility of FAC occurrence exists, and then, wall thinning rate at the identified FAC occurrence zone is evaluated to obtain the preparation time for applying countermeasures. Wall thinning rates were calculated with the coupled models of static electrochemical analysis and dynamic double oxide layer analysis. Anodic current density and electrochemical corrosion potential (ECP) were calculated with the static electrochemistry model based on an Evans diagram and ferrous ion release rate determined by the anodic current density was applied as input for the dynamic double oxide layer model. Some of the dissolved ferrous ion was removed to the bulk water and others precipitated on the surface as magnetite particles. The thickness of oxide layer was calculated with the dynamic double oxide layer model and then was applied as input for the electrochemistry model. It was confirmed that the calculated results based on the coupled models resulted good agreement with the measured ones. Higher ECP was essential for preventing FAC rate. Moderated conditions due to lower mass transfer coefficients resulted in thicker oxide layer thickness and then higher ECP, while moderated corrosion conditions due to higher oxidant concentrations resulted in larger hematite/magnetite rate and then higher ECP. (author)

  1. The effects of aging time on the size, morphology, oriented attachment and magnetic behavior of hematite nanocrystals synthesized by forced hydrolysis of FeIII solutions

    International Nuclear Information System (INIS)

    Luna, C.; Barriga-Castro, E.D.; Mendoza-Reséndez, R.

    2014-01-01

    Graphical abstract: -- Abstract: Three-dimensional (3-D) nanoarchitectures composed of self-organized hematite nanocrystals were successfully prepared by thermally induced hydrolysis of iron (III) solutions in the presence of urea and without additional stabilizers. The size, morphology and microstructure of these nanocrystal aggregates were investigated as a function of aging time using X-ray diffraction, transmission electron microscopy and selected area electron diffraction. The evolution of the microstructural parameters, including crystallite size, root mean square strain and lattice parameters, was analyzed by the Rietveld method using the MAUD software program and adopting the size–strain–shape Popa model. In addition, vibrating-sample magnetometry measurements were carried out to examine the magnetic behavior of the nanoarchitectures. These studies suggested that the formation mechanism of the observed nanoarchitectures consisted of several self-organization processes linked in hierarchical levels. The nanocrystals within these nanoarchitectures grew in size by Ostwald ripening and subsequent grain growth when they were aged at 98 °C in tightly capped tubes for an aging time that varied from 2 h up to 45 days. The crystal morphology evolved favoring a rhombohedral shape until intergrowth between the densely packed nanocrystals occurred. Consequently, the morphology of the nanoarchitectures, their effective magnetic anisotropy, the occurrence of the Morin transition and the exchange bias effect were also strongly dependent on the aging time

  2. Local vibrational dynamics of hematite (α-Fe{sub 2}O{sub 3}) studied by extended x-ray absorption fine structure and molecular dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Sanson, A., E-mail: andrea.sanson@unipd.it [Dipartimento di Fisica e Astronomia - Università di Padova, Padova (Italy); Mathon, O.; Pascarelli, S. [ESRF - European Synchrotron Radiation Facility, Grenoble (France)

    2014-06-14

    The local vibrational dynamics of hematite (α-Fe{sub 2}O{sub 3}) has been investigated by temperature-dependent extended x-ray absorption fine structure spectroscopy and molecular dynamics simulations. The local dynamics of both the short and long nearest-neighbor Fe–O distances has been singled out, i.e., their local thermal expansion and the parallel and perpendicular mean-square relative atomic displacements have been determined, obtaining a partial agreement with molecular dynamics. No evidence of the Morin transition has been observed. More importantly, the strong anisotropy of relative thermal vibrations found for the short Fe–O distance has been related to its negative thermal expansion. The differences between the local dynamics of short and long Fe–O distances are discussed in terms of projection and correlation of atomic motion. As a result, we can conclude that the short Fe–O bond is stiffer to stretching and softer to bending than the long Fe–O bond.

  3. Colour and toxic characteristics of metakaolinite–hematite pigment for integrally coloured concrete, prepared from iron oxide recovered from a water treatment plant of an abandoned coal mine

    International Nuclear Information System (INIS)

    Sadasivam, Sivachidambaram; Thomas, Hywel Rhys

    2016-01-01

    A metakaolinite-hematite (KH) red pigment was prepared using an ocherous iron oxide sludge recovered from a water treatment plant of an abandoned coal mine. The KH pigment was prepared by heating the kaolinite and the iron oxide sludge at kaolinite's dehydroxylation temperature. Both the raw sludge and the KH specimen were characterised for their colour properties and toxic characteristics. The KH specimen could serve as a pigment for integrally coloured concrete and offers a potential use for the large volumes of the iron oxide sludge collected from mine water treatment plants. - Graphical abstract: A kaolinite based red pigment was prepared using an ocherous iron oxide sludge recovered from an abandoned coal mine water treatment plant. Display Omitted - Highlights: • A red pigment was prepared by heating a kaolinite and an iron oxide sludge. • The iron oxide and the pigment were characterised for their colour properties. • The red pigment can be a potential element for integrally coloured concrete.

  4. Transport coefficients and orientational distributions of dilute colloidal dispersions composed of hematite particles (for an external magnetic field parallel to the angular velocity vector of simple shear flow)

    International Nuclear Information System (INIS)

    Satoh, Akira; Hayasaka, Ryo; Majima, Tamotsu

    2008-01-01

    We have treated a dilute dispersion composed of ferromagnetic rodlike particles with a magnetic moment normal to the particle axis, such as hematites, to investigate the influences of the magnetic field strength, shear rate, and random forces on the orientational distribution of rodlike particles and also on transport coefficients, such as viscosity and diffusion coefficient. In the present analysis, these rodlike particles are assumed to conduct the rotational Brownian motion in a simple shear flow as well as an external magnetic field. The results obtained here are summarized as follows. In the case of a strong magnetic field and a smaller shear rate, the rodlike particle can freely rotate in the xy-plane with the magnetic moment continuing to point the magnetic field direction. On the other hand, for a strong shear flow, the particle has a tendency to incline in the flow direction with the magnetic moment pointing to the magnetic field direction. In the case of the magnetic field applied normal to the direction of the sedimentation, the diffusion coefficient gives rise to smaller values than expected, since the rodlike particle sediments with the particle axis inclining toward directions normal to the movement direction and, of course, toward the direction along that direction

  5. In silico approach to investigating the adsorption mechanisms of short chain perfluorinated sulfonic acids and perfluorooctane sulfonic acid on hydrated hematite surface.

    Science.gov (United States)

    Feng, Hongru; Lin, Yuan; Sun, Yuzhen; Cao, Huiming; Fu, Jianjie; Gao, Ke; Zhang, Aiqian

    2017-05-01

    Short chain perfluorinated sulfonic acids (PFSAs) that were introduced as alternatives for perfluorooctane sulfonic acid (PFOS) have been widely produced and used. However, few studies have investigated the environmental process of short chain PFSAs, and the related adsorption mechanisms still need to be uncovered. The water-oxide interface is one of the major environmental interfaces that plays an important role in affecting the adsorption behaviour and transport potential of the environmental pollutant. In this study, we performed molecular dynamics simulations and quantum chemistry calculations to investigate the adsorption mechanisms of five PFSAs and their adsorption on hydrated hematite surface as well. Different to the vertical configuration reported for PFOS on titanium oxide, all PFSAs share the same adsorption configuration as the long carbon chains parallel to the surface. The formation of hydrogen bonds between F and inter-surface H helps to stabilize the unique configuration. As a result, the sorption capacity increases with increasing C-F chain length. Moreover, both calculated adsorption energy and partial density of states (PDOS) analysis demonstrate a PFSAs adsorption mechanism in between physical and chemical adsorption because the hydrogen bonds formed by the overlap of F (p) orbital and H (s) orbital are weak intermolecular interactions while the physical adsorption are mainly ascribed to the electrostatic interactions. This massive calculation provides a new insight into the pollutant adsorption behaviour, and in particular, may help to evaluate the environmental influence of pollutants. Copyright © 2017. Published by Elsevier Ltd.

  6. Mineralogical effects of an experimental forest fire on a goethite/ferrihydrite soil - an attempt to solve the presence of hematite and maghemite in topsoils in a temperate region

    Science.gov (United States)

    Nørnberg, Per; Vendelboe, Anders L.; Gunnlaugsson, Haraldur P.; Merrison, Jonathan P.; Finster, Kai; Jensen, Svend K.

    2010-05-01

    Isolated soil spots, a few square metres in size, as red as Munsell colour 10R ¾ are found in Denmark. These spots are well known as places that have been exposed to fire. However, a long-standing unresolved puzzle is the presence of extended areas with high iron content (8-40 %) where goethite and ferrihydrite are present in the topsoil along with hematite and maghemite. Hematite and particularly maghemite would normally not be expected to occur under the temperate humid Danish climate, but be interpreted as the result of high temperature as found in tropical areas or after forest fires. However, a body of evidence argues against these sites having been exposed to fire. In an attempt to get closer to an explanation of this iron mineralogy, an experimental forest fire was produced. The results showed a clear mineralogical zonation down to 10 cm depth. This was not observed at the natural sites, which contained a uniform mixture of goethite/ferrihydrite, hematite and maghemite down to 20 cm depth. The experimental forest fire furthermore left charcoal and ashes at the topsoil, produced high pH and decreased organic matter content, all of which is in contrast to the natural sites. Physical and chemical date as well as XRD, Mössbauer spectroscopic data and TEM micrographs from the sites will be presented. The conclusion from this work is that the mineralogy of these sites is not consistent with exposure to fire, but may rather result from long term transformation within a reducing environment, possibly involving microorganisms. References: Nørnberg, P., Vendelboe, A.L., Gunnlaugsson, H.P., Merrison, J.P., Finster, K., Jensen, S.K. 2009 Mineralogy after an experimental forest fire on Quaternary soil goethite, compared with a hematite, maghemite, goethite containing topsoil. Clay Minerals, 44, 239-247. Nørnberg, P., Gunnlaugsson, H.P., Merrison, J.P., Vendelboe, A.L. 2009: Salten Skov I: A Martian dust analogue. Planetary and Space Science, 57, 628-631. Nørnberg, P

  7. Manipulating Conduction in Metal Oxide Semiconductors: Mechanism Investigation and Conductance Tuning in Doped Fe2O3 Hematite and Metal/Ga2O3/Metal Heterostructure

    Science.gov (United States)

    Zhao, Bo

    This study aims at understanding the fundamental mechanisms of conduction in several metal oxide semiconductors, namely alpha-Fe2O 3 and beta-Ga2O3, and how it could be tuned to desired values/states to enable a wide range of application. In the first effort, by adding Ti dopant, we successfully turned Fe2O3 from insulating to conductive by fabricated compositionally and structurally well-defined epitaxial alpha-(TixFe1-x)2 O3(0001) films for x ≤ 0.09. All films were grown by oxygen plasma assisted molecular beam epitaxy on Al2O3(0001) sapphire substrate with a buffer layer of Cr2O3 to relax the strain from lattice mismatch. Van der Pauw resistivity and Hall effect measurements reveal carrier concentrations between 1019 and 1020 cm-3 at room temperature and mobilities in the range of 0.1 to 0.6 cm2/V˙s. Such low mobility, unlike conventional band-conduction semiconductor, was attributed to hopping mechanism due to strong electron-phonon interaction in the lattice. More interestingly, conduction mechanism transitions from small-polaron hopping at higher temperatures to variable range hopping at lower temperatures with a transition temperature between 180 to 140 K. Consequently, by adding Ti dopant, conductive Fe 2O3 hematite thin films were achieved with a well-understood conducting mechanism that could guide further device application such as spin transistor and water splitting. In the case of Ga2O3, while having a band gap as high as 5 eV, they are usually conductive for commercially available samples due to unintentional Si doping. However, we discovered the conductance could be repeatedly switched between high resistance state and low resistance state when made into metal/Ga2O3 /metal heterostructure. However, to obtain well controlled switching process with consistent switching voltages and resistances, understanding switching mechanism is the key. In this study, we fabricated resistive switching devices utilizing a Ni/Ga2O3/Ir heterostructure. Bipolar

  8. Amending Jasper County, Missouri soils with biochar and ...

    Science.gov (United States)

    Abandoned mines and the residuals from mining across the U.S. pose a considerable, pervasive risk to human health and the environment. Many soils in the Tri-State-Mining District (TSMD), located where Missouri, Kansas and Oklahoma meet, have been affected by the residuals of historic lead and zinc mining. Here we describe a research collaboration between ORD and Region 7 to investigate the use of customized soil amendments, which will include biochar, as a tool to provide both soil remediation and reestablishment of a soil-stabilizing native plant community at sites in the TSMD. Biochar is a charcoal-like, carbon-rich, porous by-product of thermal pyrolysis or gasification. A benefit of using biochar is the ability to engineer its properties to correspond to specific soil remediation needs. Specifically, it has properties that make it well suited for use in remediating mine soils and reestablishing vegetation, with studies indicating that biochar can complex and immobilize heavy metals. This is of critical importance for mining influenced sites. However, the optimized biochar properties for the remediation of acidic mine soils are not yet fully known. Biochar can be produced to have a range of pH values, depending upon feedstock and pyrolysis or gasification conditions, and post-production activation. Therefore, this material may be used as a liming agent to raise soil pH. Additionally, some biochars have been shown to improve soil water holding capacities and

  9. DIGITAL FLOOD INSURANCE RATE MAP DATABASE, JASPER COUNTY, TX

    Data.gov (United States)

    Federal Emergency Management Agency, Department of Homeland Security — The Digital Flood Insurance Rate Map (DFIRM) Database depicts flood risk information and supporting data used to develop the risk data. The primary risk...

  10. Variabilidade de goethita e hematita via dissolução redutiva em solos de região tropical e subtropical Goethite and hematite variability via reductive dissolution in soils from tropical and subtropical regions

    Directory of Open Access Journals (Sweden)

    Alberto Vasconcellos Inda Junior

    2005-12-01

    combinou baixa substituição por Al3+ e alta ASE. A caracterização de populações heterogêneas de goethita pode ampliar a utilização deste óxido como indicador de processos pedogênicos em solos poligenéticos, bem como contribuir para um melhor entendimento do comportamento químico e físico desses solos.Iron oxides from 22 soil samples (19 from argillic B horizons; one from a plinthic B horizon; one from a cambic horizon and one from a C horizon were subjected to selective dissolution with sodium dithionite-citrate-bicarbonate at 20 ºC in time intervals of 5 to 3,840 minutes. Mean coherence lengths (MCL, specific surface area (SSA and iron by aluminum substitution (Al3+-substitution of goethite and hematite in untreated sub-samples and in selected sub-samples treated during selective dissolution were estimated by X ray diffraction analysis (XRD. The control of remaining goethite and hematite phases after each time interval of selective dissolution was carried out by differential X ray diffraction (DXRD. The crystal dissolution kinetics was described by segmentation of the iron dissolution curve as a time function at the intervals where dissolution occurred linearly. Dissolution rates of each linear segment were obtained by the angular coefficient of the straight line of each linear segment. In the latossolic goethitic samples, this methodology discriminated different phases of goethite (heterogeons populations regarding Al3+-substitution, MCL and SSA, making possible to classify goethite stability degrees (low, medium, high, and very high stability. Goethite samples from young pedogenic environments and latossolic hematitic samples were characterized by higher crystal homogeneity, which were classified as being of low and medium stability. In goethitic samples, crystal proportion with high stability (high Al3+-substitution and crystallinity in each population showed positive association with gibbisite proportion compared to caulinite in the samples. Hematite

  11. Simultaneous catalytic degradation of 2,4-D and MCPA herbicides using sulfate radical-based heterogeneous oxidation over persulfate activated by natural hematite (α-Fe2O3/PS)

    Science.gov (United States)

    Kermani, Majid; Mohammadi, Farzad; Kakavandi, Babak; Esrafili, Ali; Rostamifasih, Zeinab

    2018-06-01

    Herein, a sulfate radical (SO4rad -)-based oxidation process was utilized for simultaneous degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) and 2-methyl-4-chlorophenoxyacetic acid (MCPA) herbicides using mesoporous hematite-based natural semi-conductor minerals (HM-NSMs) as efficient activators of persulfate (PS). The features of the catalyst were characterized using field emission scanning electron microscopy (FESEM); Brunauer, Emmett and Teller (BET) analysis; X-ray diffraction (XRD); and energy-dispersive X-ray spectroscopy (EDS). The effect of some operational parameters, including solution pH, catalyst loading, PS dosage and temperature, on the performance system of PS/HM-NSMs was examined. A plausible oxidation mechanism for degradation of both pollutants was also proposed. Increasing the removal efficiency of herbicides follows the order of PS/HM-NSM > HM-NSM > PS. In all experiments, the 2,4-D removal rates were slightly lower than those for MCPA, indicating that 2,4-D has a more recalcitrant nature than MCPA. Under optimized conditions, degradation rates of 68.1% and 74.5% were achieved for 2,4-D and MCPA, respectively, during a 120-min reaction. HM-NSM displays a highly synergistic effect on the degradation of herbicides in the presence of PS. The trapping experiments demonstrated that both OHrad and SO4rad - radicals contribute significantly during the degradation of 2,4-D and MCPA and that sulfate radicals were the dominant species. A mineralization degree of 36% was obtained under optimum conditions. In conclusion, the coupling of PS and HM-NSM is a promising and effective technique to degrade organic matter for the treatment of herbicide-contaminated waters and wastewaters under real conditions.

  12. Size dependent polaronic conduction in hematite

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Monika; Banday, Azeem; Murugavel, Sevi [Department of Physics and Astrophysics, University of Delhi, Delhi – 110 007 (India)

    2016-05-23

    Lithium Ion Batteries have been attracted as the major renewable energy source for all portable electronic devices because of its advantages like superior energy density, high theoretical capacity, high specific energy, stable cycling and less memory effects. Recently, α-Fe{sub 2}O{sub 3} has been considered as a potential anode material due to high specific capacity, low cost, high abundance and environmental benignity. We have synthesized α-Fe{sub 2}O{sub 3} with various sizes by using the ball milling and sol-gel procedure. Here, we report the dc conductivity measurement for the crystallite size ranging from 15 nm to 50 nm. It has been observed that the enhancement in the polaronic conductivity nearly two orders in magnitude while reducing the crystallite size from bulk into nano scale level. The enhancement in the conductivity is due to the augmented to compressive strain developed in the material which leads to pronounced decrease in the hopping length of polarons. Thus, nanocrystaline α-Fe{sub 2}O{sub 3} may be a better alternative anode material for lithium ion batteries than earlier reported systems.

  13. Size dependent polaronic conduction in hematite

    International Nuclear Information System (INIS)

    Sharma, Monika; Banday, Azeem; Murugavel, Sevi

    2016-01-01

    Lithium Ion Batteries have been attracted as the major renewable energy source for all portable electronic devices because of its advantages like superior energy density, high theoretical capacity, high specific energy, stable cycling and less memory effects. Recently, α-Fe_2O_3 has been considered as a potential anode material due to high specific capacity, low cost, high abundance and environmental benignity. We have synthesized α-Fe_2O_3 with various sizes by using the ball milling and sol-gel procedure. Here, we report the dc conductivity measurement for the crystallite size ranging from 15 nm to 50 nm. It has been observed that the enhancement in the polaronic conductivity nearly two orders in magnitude while reducing the crystallite size from bulk into nano scale level. The enhancement in the conductivity is due to the augmented to compressive strain developed in the material which leads to pronounced decrease in the hopping length of polarons. Thus, nanocrystaline α-Fe_2O_3 may be a better alternative anode material for lithium ion batteries than earlier reported systems.

  14. Neutron Investigation of Magnon Spectrum in Haematite; Etude du Spectre de Magnons dans l'Hematite, au Moyen des Neutrons; Nejtronnoe issledovanie spektra magnona v gematite; Estudio, por Metodos Neutronicos, del Espectro de Magnones en la Hematita

    Energy Technology Data Exchange (ETDEWEB)

    Dimitrijevic, Z.; Rzany, H.; Todorovic, J.; Wanic, A. [Institute for Nuclear Physics Cracow (Poland)

    1965-04-15

    faites a Vinea, dans le reacteur RA, au moyen d'un spectrometre a cristal. Des neutrons monochromatiques ({lambda} = 1.314A) ont ete diffuses par un grand monocristal d'hematite ({alpha}-Fe{sub 2}O{sub 3}). Les auteurs ont etudie la distribution angulaire des neutrons diffuses inelastiquement. Pour plusieurs angles de decalage {Delta}{theta} du cristal, ils ont mesure la largeur {Gamma} du faisceau de neutrons diffuses (appele cone de diffusion). Ils ont attribue ce cone a la surface de diffusion des magnons qui entoure le point du reseau reciproque (1,1,1). Pour plusieurs vitesses de magnons, ils ont mesure {Gamma}, en fonction de l'angle de decalage, et l*ont comparee aux points experimentaux. Ils ont constate que dans la direction [111], la vitesse avait une valeur egale a 25,5{+-}1,0 km/s. Ils ont decouvert une anisotropie structurelle de la relation de dispersion des magnons. Ils ont note que la vitesse etait plus elevee pour les directions de propagation paralleles a l'axe [111], ce qui concorde qualitativement avec les mesures anterieures (faites par Riste et d'autres) qui ont donne v = 38 km/s. Il n'a pas ete possible de mettre en evidence l'existence d'une discontinuite Eg dans la bande acoustique de l'energie des magnons. Selon les evaluations, Eg doit avoir une valeur inferieure a 1 meV. En utilisant le formalisme de Wallace, les auteurs ont calcule les relations de dispersion des magnons dans l'hematite. A cet effet, ils ont admis l'existence de deux integrales d'echange J{sub 1} et J{sub 2} qui ne disparaissent pas. J{sub 1} et J{sub 2} expriment le couplage a superechange d'energie entre les spins d'ions Fe voisins lies par l'intermediaire d'un ion oxygene. Les angles Fe-O-Fe des liaisons considerees sont respectivement de 132 et 126 Degree-Sign . Les resultats theoriques et les donnees experimentales actuelles concordent de facon satisfaisante lorsque SJ{sub 1} = SJ{sub 2} = 5,1 meV. Outre la branche acoustique des magnons, les calculs ont revele l

  15. Alteration of submarine volcanic rocks in oxygenated Archean oceans

    Science.gov (United States)

    Ohmoto, H.; Bevacqua, D.; Watanabe, Y.

    2009-12-01

    Most submarine volcanic rocks, including basalts in diverging plate boundaries and andesites/dacites in converging plate boundaries, have been altered by low-temperature seawater and/or hydrothermal fluids (up to ~400°C) under deep oceans; the hydrothermal fluids evolved from shallow/deep circulations of seawater through the underlying hot igneous rocks. Volcanogenic massive sulfide deposits (VMSDs) and banded iron formations (BIFs) were formed by mixing of submarine hydrothermal fluids with local seawater. Therefore, the behaviors of various elements, especially of redox-sensitive elements, in altered submarine volcanic rocks, VMSDs and BIFs can be used to decipher the chemical evolution of the oceans and atmosphere. We have investigated the mineralogy and geochemistry of >500 samples of basalts from a 260m-long drill core section of Hole #1 of the Archean Biosphere Drilling Project (ABDP #1) in the Pilbara Craton, Western Australia. The core section is comprised of ~160 m thick Marble Bar Chert/Jasper Unit (3.46 Ga) and underlying, inter-bedded, and overlying submarine basalts. Losses/gains of 65 elements were quantitatively evaluated on the basis of their concentration ratios against the least mobile elements (Ti, Zr and Nb). We have recognized that mineralogical and geochemical characteristics of many of these samples are essentially the same as those of hydrothermally-altered modern submarine basalts and also those of altered volcanic rocks that underlie Phanerozoic VMSDs. The similarities include, but are not restricted to: (1) the alteration mineralogy (chlorite ± sericite ± pyrophyllite ± carbonates ± hematite ± pyrite ± rutile); (2) the characteristics of whole-rock δ18O and δ34S values; (3) the ranges of depletion and enrichment of Si, Al, Mg, Ca, K, Na, Fe, Mn, and P; (4) the enrichment of Ba (as sulfate); (5) the increases in Fe3+/Fe2+ ratios; (6) the enrichment of U; (7) the depletion of Cr; and (8) the negative Ce anomalies. Literature data

  16. Experimental Heating of Moravian Cherts and its Implication for Palaeolithic Chipped Stone Assemblages

    Czech Academy of Sciences Publication Activity Database

    Moník, M.; Nerudová, Z.; Schnabl, Petr

    2017-01-01

    Roč. 59, č. 6 (2017), s. 1190-1206 ISSN 0003-813X Institutional support: RVO:67985831 Keywords : lithics * heat treatment * Palaeolithic * magnetic susceptibility * colour measurement * isothermal remanent magnetization Subject RIV: AC - Archeology, Anthropology, Ethnology OBOR OECD: Archaeology Impact factor: 1.470, year: 2016

  17. Limestone and chert in tectonic blocks from the Esk Head subterrane, South Island, New Zealand

    Science.gov (United States)

    Silberling, Norman J.; Nichols, K.M.; Bradshaw, J.D.; Blome, C.D.

    1988-01-01

    The Esk Head subterrane is a continuous belt, generally 10-20 km wide, of tectonic melange and broken formation on the South Island of New Zealand. This subterrane separates older and younger parts of the Torlesse terrane which is an extensive accretionary prism composed mostly of quartzo-feldspathic, submarine-fan deposits ranging from Permian to Early Cretaceous in age. The Esk Head subterrane of the Torlesse is especially informative because it includes within it conspicuous tectonic blocks of submarine basalt and a variety of basalt-associated seamount and sea-floor limestones and cherty rocks thought to be representative of the subducted plate. Paleogeographic inferences drawn from megafossils, bioclasts, and radiolarians, as well as from carbonate cements, indicate deposition of the oceanic sedimentary rocks at paleolatitudes somewhat lower than that of the New Zealand part of the Gondwana margin, but higher than paleoequatorial latitudes. -Authors

  18. Cloud Experiment. View inside the chamber with Jasper Kirkby, Head leader of the project.

    CERN Multimedia

    Maximilien Brice

    2009-01-01

    CLOUD, the cutting-edge physics experiment that will shed light on climate-related matters, has finished its assembly phase and is starting taking data using a beam of protons from the Proton Synchrotron.

  19. El encuentro de Nishida Kitaró con la fenomenología: Husserl, Heideggery Jaspers

    Directory of Open Access Journals (Sweden)

    Agustín JACINTO ZAVALA

    2009-11-01

    Full Text Available RESUMEN: Nishida es uno de los primeros introductores de la fenomenología en Japón y algunos de sus discípulos, miembros de la Escuela de Kioto, la estudiaron en Alemania bajo Husserl y Heidegger. En este escrito he querido hacer un recorrido por los textos nishidianos que nos permita tener una visión general del encuentro de Nishida con la fenomenología. Aquí veremos algunos de los principales temas o problemas que el filósofo japonés Nishida Kitaró (1870-1945 señala en la fenomenología o que comparte con ella. Mi intento al presentar estos aspectos es invitar a especialistas en filosofía comparada y especialistas en fenomenología a considerar la importancia o trivialidad de las observaciones de Nishida y la posible respuesta a sus críticas. Huelga decir que se hace necesario un estudio más detallado de la carrera textual de Nishida para dar cuenta cabal del esbozo que ahora presento.ABSTRACT: Nishida is one of the first scholars to introduce phenomenology in Japan, and some of his disciples, members of the Kyoto School, studied it in Germany under Husserl and Heidegger. In this paper, I have examined Nishida's texts in order to give the reader a general view of his encounter with phnomenology. We will see some of the main themes or problems that the Japanese philosopher Nishida Kitaró (1870- 1945 points out in phenomenology, or that he shares with it. Through this presentation, I would like to invite spercialists in phenomenology and comparative philosophy to consider the importance or triviality of Nishida's comments and possible responses to his criticisms. Needless to say, a detailed study of Nishida's textual career would be required in order to give a complete account of the outline presented here.

  20. DIGITAL FLOOD INSURANCE RATE MAP DATABASE, JASPER COUNTY, MISSISSIPPI AND INCORPORATED AREAS

    Data.gov (United States)

    Federal Emergency Management Agency, Department of Homeland Security — The Digital Flood Insurance Rate Map (DFIRM) Database depicts flood risk information and supporting data used to develop the risk data. The primary risk...

  1. DIGITAL FLOOD INSURANCE RATE MAP DATABASE, Jasper COUNTY AND INCORPORATED AREAS, MO, USA

    Data.gov (United States)

    Federal Emergency Management Agency, Department of Homeland Security — The Digital Flood Insurance Rate Map (DFIRM) Database depicts flood risk information and supporting data used to develop the risk data. The primary risk...

  2. 76 FR 13205 - Piedmont National Wildlife Refuge, Jones and Jasper Counties, GA; Final Comprehensive...

    Science.gov (United States)

    2011-03-10

    ...; fishing; environmental education and interpretation; wildlife observation and photography; boating; camping (associated with big game hunts, scouts, and other youth organizations only); firewood cutting... game-management demonstration area'' to demonstrate that wildlife could be restored on worn out, eroded...

  3. 75 FR 26979 - Piedmont National Wildlife Refuge, Jones and Jasper Counties, GA

    Science.gov (United States)

    2010-05-13

    ... acquisition; (3) forest and fire management and education; (4) cane break restoration; (5) invasive species... area with smaller burn units on a 2-year rotation. We would prioritize the need for removal of invasive... expand invasive plant species control from uplands to include other habitat types to reduce adverse...

  4. Mobility of Hematite Submicron Particles in Water Solutions of Sugar

    International Nuclear Information System (INIS)

    Fornal, P.; Stanek, J.

    2008-01-01

    The mobility of the 100 nm Fe 2 O 3 particles in dense water solutions of sugar (sucrose) was determined from the analysis of the resonance absorption line shape of the Moessbauer spectra recorded in the -5 o C to 40 o C temperature range for different sugar concentrations. The discrepancy between the experimental data and the prediction of the classical theory of Brownian movement are interpreted in the term of the short observation time and the interaction between the solid particles in fluids, which extends in water up to 300 nm. The sedimentation process in the studied colloids was observed. (authors)

  5. Enhanced Photoelectrochemical Response of Zn-Dotted Hematite

    Directory of Open Access Journals (Sweden)

    Saroj Kumari

    2007-01-01

    Full Text Available Photoelectrochemical response of thin films of α-Fe2O3, Zn doped α-Fe2O3, and Zn dots deposited on doped α-Fe2O3 prepared by spray pyrolysis has been studied. Samples of Zn dots were prepared using thermal evaporation method by evaporating Zn through a mesh having pore diameter of 0.7 mm. The presence of Zn-dotted islands on doped α-Fe2O3 surface exhibited significantly large photocurrent density as compared to other samples. An optimum thickness of Zn dots ∼230 Å is found to give enhanced photoresponse. The observed results are analyzed with the help of estimated values of resistivity, band gap, flatband potential, and donor density.

  6. Density functional theory study of Al-doped hematite

    International Nuclear Information System (INIS)

    Rivera, Richard; Stashans, Arvids; Piedra, Lorena; Pinto, Henry P

    2012-01-01

    Using first-principles density functional theory calculations within the generalized gradient approximation (GGA) as well as the GGA+U approach, we study Al-doped α-Fe 2 O 3 crystals. Structural, electronic, magnetic and optical properties due to impurity incorporation have been investigated and discussed in detail. Atomic displacements and Bader charges on atoms have been computed, showing that Al dopant converts the chemical bonding in its neighbourhood into a more ionic one. This work enhances our knowledge about how a crystalline lattice reacts in the presence of an Al impurity. It was found that Al incorporation produces some local changes in the band structure of the material without the creation of local energy levels within the band gap. The results provide evidence for changes in the magnetic moments in the vicinity of a defect, which means that α-Fe 2 O 3 doped with aluminum might not act as an antiferromagnetic substance.

  7. Orientation Sensitivity of Oxygen Evolution Reaction on Hematite

    NARCIS (Netherlands)

    Zhang, X. Q.; Cao, C.; Bieberle, A.

    2016-01-01

    The sensitivity of the surface orientation on photoelectrochemical water oxidation has recently been reported by experimental studies. However, a detailed theoretical understanding is still missing. Density functional theory + Hubbard U (DFT + U) calculations are therefore carried out in order to

  8. Study of the maguemite-hematite transformation by magnetic resonance

    International Nuclear Information System (INIS)

    Portella, P.D.

    1979-08-01

    The conversion of γ-Fe 2 O 3 powders to α-Fe 2 O 3 has been studied with the magnetic resonance technique. The residual fraction of γ-Fe 2 O 3 was measured for several times and temperatures of isothermal treatments, in the range 450 0 C - 550 0 C. The transformation can be described by a first order Kinetic equation and the apparent activation energy is about 200 kJ/mol (48 kcal/mol). This value is independent of temperature and particle size. The experimental data suggest that the reaction is growth-controlled and nucleation occurs preferably at the particle surface. (Author) [pt

  9. Geochemistry and the origin of the Mamouniyeh iron ore-terra rossa deposit, Markazi Province - Iran

    Directory of Open Access Journals (Sweden)

    Marziyeh Mahboubiyan Fard

    2017-11-01

    chert and minor jasper. Some secondary dolomite and calcite, filling the fractures and open spaces are found. Clay minerals are also minor constituents of the ore. The remaining fossils of green-blue algae indicate the conditions of iron deposition and effective biological processes in oxidizing Fe+2 and creation of new oxide minerals in a sedimentary basin. XRD studies show that tetraferriannite, hisingerite, barite, dolomite and calcite are present in addition to dominant hematite and quartz minerals. Hisingerite is formed in sedimentary iron deposits during hydrothermal alteration (Whelan and Goldich., 1961. Tetraferriannite occurs in low grade iron formations (Miyano, 1982. Structurally, the mineralization is controlled by a tectonic zone in which abundant breccias and faults are well found. The amount of Fe2O3 ranges between 11.62% and 65.73%, with an average value of 31% Fe2O3. The amounts of Cr (3-95 ppm and Zr (<5-29 ppm are low; while, the deposit contains a moderate amount of V (26-189 ppm and high concentrations of Zn (28-218 ppm, Sr (66-1462 ppm and Ba (62-5511 ppm. The concentration of REEs shows that total amount of these elements is variable and it falls in the range of 2.34-12.74 ppm. The amount of LREEs falls in the range of 1.66-11.94 ppm and that of HREEs falls in 0.21-2.22 ppm. These values clearly indicate the enrichment of ore in LREEs relative to HREEs. The Eu anomaly (Eu/Eu* lies in the range of 1.32-10.2, indicating positive Eu anomalies. The Ce anomalies (Ce/Ce* fall in the range of 0.076-0.52, suggesting negative anomaly. Discussion The low concentration of Cr and Zr, and high values of V, Zn and Sr in the ore suggest that mineralization is related to submarine volcanic activities. Geochemical data, including chondrite-normalized REE patterns, indicate that seafloor hydrothermal fluids are the most probable source for mineralizing solutions. The ∑(Cu+Co+Ni vs. ∑REE diagram also indicates the role of deep sea hydrothermal fluids in the

  10. The degassing history of the Earth: Noble gas studies of Archaean cherts and zero age glassy submarine basalts

    Science.gov (United States)

    Hart, R.; Hogan, L.

    1985-01-01

    Recent noble gas studies suggests the Earth's atmosphere outgassed from the Earth's upper mantle synchronous with sea floor spreading, ocean ridge hydrothermal activity and the formation of continents by partial melting in subduction zones. The evidence for formation of the atmosphere by outgassing of the mantle is the presence of radionuclides H3.-4, Ar-040 and 136 Xe-136 in the atmosphere that were produced from K-40, U and Th in the mantle. How these radionuclides were formed is reviewed.

  11. Mineralogy and geochemistry of two metamorphosed sedimentary manganese deposits, Sierra Nevada, California, USA

    Science.gov (United States)

    Flohr, M.J.K.; Huebner, J.S.

    1992-01-01

    Laminated to massive rhodochrosite, hausmannite, and Mn-silicates from the Smith prospect and Manga-Chrome mine, Sierra Nevada, California were deposited as ocean floor sediments associated with chert and shale. The principal lithologies at Smith are chert, argillite, rhodochrosite-, hausmannite- and chlorite-rich layers, and relatively uncommon layers of jacobsite. The Manga-Chrome mine also contains layers rich in manganoan calcite and caryopilite. Tephroite, rhodonite, spessartine, and accessory alleghanyite and sonolite formed during metamorphism. Volcaniclastic components are present at Manga-Chrome as metavolcanic clasts and as Mn-poor, red, garnet- and hematite-rich layers. There is no evidence, such as relict lithologies, that Mn was introduced into Mn-poor lithologies such as chert, limestone or mudstone. Replacement of Mn-poor phases by Mn-rich phases is observed only in the groundmass of volcanic clasts that appear to have fallen into soft Mn-rich mud. Manganiferous samples from the Smith prospect and Manga-Chrome mine have high Mn Fe and low concentrations of Ni, Cu, Zn, Co, U, Th and the rare-earth elements that are similar to concentrations reported from other ancient Mn deposits found in chert-greenstone complexes and from manganiferous sediments and crusts that are forming near modern sea floor vents. The Sierra Nevada deposits formed as precipitates of Mn-rich sediments on the sea floor, probably from mixtures of circulating hydrothermal fluids and seawater. The composition of a metabasalt from the Smith prospect is consistent with those of island-arc tholeiites. Metavolcanic clasts from the Manga-Chrome mine are compositionally distinct from the Smith metabasalt and have alkaline to calc-alkaline affinities. A back-arc basin is considered to be the most likely paleoenvironment for the formation of the Mn-rich lenses at the Manga-Chrome mine and, by association, the Smith prospect. Layers of rhodochrosite, hausmannite and chert preserve the

  12. Oxygen in the Martian atmosphere: Regulation of PO2 by the deposition of iron formations on Mars

    Science.gov (United States)

    Burns, Roger G.

    1992-01-01

    During Earth's early history, and prior to the evolution of its present day oxygenated atmosphere, extensive iron rich siliceous sedimentary rocks were deposited, consisting of alternating layers of silica (chert) and iron oxide minerals (hematite and magnetite). The banding in iron formations recorded changes of atmosphere-hydrosphere interactions near sea level in the ancient ocean, which induced the oxidation of dissolved ferrous iron, precipitation of insoluble ferric oxides and silica, and regulation of oxygen in Earth's early atmosphere. Similarities between the Archean Earth and the composition of the present day atmosphere on Mars, together with the pervasive presence of ferric oxides in the Martian regolith suggest that iron formation might also have been deposited on Mars and influenced the oxygen content of the Martian atmosphere. Such a possibility is discussed here with a view to assessing whether the oxygen content of the Martian atmosphere has been regulated by the chemical precipitation of iron formations on Mars.

  13. Electronic and optical properties of new multifunctional materials via half-substituted hematite: First principles calculations

    KAUST Repository

    Yang, Hua

    2012-01-01

    Electronic structure and optical properties of α-FeMO 3 systems (M = Sc, Ti, V, Cr, Cu, Cd or In) have been investigated using first principles calculations. All of the FeMO 3 systems have a large net magnetic moment. The ground state of pure α-Fe 2O 3 is an antiferromagnetic insulator. For M = Cu or Cd, the systems are half-metallic. Strong absorption in the visible region can be observed in the Cu and Cd-doped systems. Systems with M = Sc, Ti, V, Cr or In are not half-metallic and are insulators. The strongest peaks shift toward shorter wavelengths in the absorption spectra. It is concluded that transition metal doping can modify the electronic structure and optical properties of α-FeMO 3 systems. This journal is © 2012 The Royal Society of Chemistry.

  14. Band-gap measurements of bulk and nanoscale hematite by soft x-ray spectroscopy

    DEFF Research Database (Denmark)

    Gilbert, B.; Frandsen, Cathrine; Maxey, E.R.

    2009-01-01

    Chemical and photochemical processes at semiconductor surfaces are highly influenced by the size of the band gap, and ability to control the band gap by particle size in nanomaterials is part of their promise. The combination of soft x-ray absorption and emission spectroscopies provides band......-gap determination in bulk and nanoscale itinerant electron semiconductors such as CdS and ZnO, but this approach has not been established for materials such as iron oxides that possess band-edge electronic structure dominated by electron correlations. We performed soft x-ray spectroscopy at the oxygen K...

  15. Atomic layer epitaxy of hematite on indium tin oxide for application in solar energy conversion

    Science.gov (United States)

    Martinson, Alex B.; Riha, Shannon; Guo, Peijun; Emery, Jonathan D.

    2016-07-12

    A method to provide an article of manufacture of iron oxide on indium tin oxide for solar energy conversion. An atomic layer epitaxy method is used to deposit an uncommon bixbytite-phase iron (III) oxide (.beta.-Fe.sub.2O.sub.3) which is deposited at low temperatures to provide 99% phase pure .beta.-Fe.sub.2O.sub.3 thin films on indium tin oxide. Subsequent annealing produces pure .alpha.-Fe.sub.2O.sub.3 with well-defined epitaxy via a topotactic transition. These highly crystalline films in the ultra thin film limit enable high efficiency photoelectrochemical chemical water splitting.

  16. Electronic and optical properties of new multifunctional materials via half-substituted hematite: First principles calculations

    KAUST Repository

    Yang, Hua; Mi, Wenbo; Bai, Haili; Cheng, Yingchun

    2012-01-01

    Electronic structure and optical properties of α-FeMO 3 systems (M = Sc, Ti, V, Cr, Cu, Cd or In) have been investigated using first principles calculations. All of the FeMO 3 systems have a large net magnetic moment. The ground state of pure α-Fe 2

  17. Influence of hematite nanorods on the mechanical properties of epoxy resin

    Czech Academy of Sciences Publication Activity Database

    Bogdanović, G.; Kovač, T. S.; Džunuzović, E. S.; Špírková, Milena; Ahrenkiel, P. S.; Nedeljković, J. M.

    2017-01-01

    Roč. 82, č. 4 (2017), s. 437-447 ISSN 0352-5139 R&D Projects: GA ČR(CZ) GA13-06700S Institutional support: RVO:61389013 Keywords : nanocomposites * thermosetting resin * mechanical measurements Subject RIV: CD - Macromolecular Chemistry OBOR OECD: Polymer science Impact factor: 0.822, year: 2016

  18. Phase identification and morphology study of hematite (Fe2O3) with sintering time varitions

    Science.gov (United States)

    Yazirin, Cepi; Puspitasari, Poppy; Sasongko, Muhammad Ilman Nur; Tsamroh, Dewi Izzatus; Risdanareni, Puput

    2017-09-01

    Iron oxide has been the interest of many studies due to its applications in various scientific and industrial fields including in environment, corrosion, soil science, and exhaust emissions. Iron oxide (Fe2O3) has potential applications in catalytic reactions in electronic devices such as semiconductors, paint formulations, and lithium rechargeable batteries. Fe2O3 can be synthesized through the process of stirring, decomposition of organic iron, sol-gel, combustion, and evaporating solvents. Most of the methods used involve several steps and take a long time. The aim of this research was to investigate the phase and morphology characterization of iron oxide (Fe2O3) powder with solvent ethylene glycol after being sintered for 1 hour, 2 hours and 3 hours. The characterization tools utilized were XRD, SEM-EDX, and FTIR. The results of XRD analysis showed that the Fe2O3 sintered for 1 hour had the smallest crystallite size with a diameter of 21.05 nm. In the XRD test, the beam of X-ray was shot directly at the grain being tested. The results of SEM analysis showed thatthe Fe2O3 sintered for 1 hour produced the best result due to its crystallite size of 12.36 nm and hada shape of homogeneous nanosphere; the duration of sintering indeed had a great influence on the grain size of iron oxide (Fe2O3). In addition, the results of the elemental composition analysis indicate that the longer the sintering process, the higher the concentration of O but the lower the Fe.

  19. Effect of different crystal faces on experimental interaction force and aggregation of hematite

    NARCIS (Netherlands)

    Hiemstra, T.; Riemsdijk, van W.H.

    1999-01-01

    Charging is a basic property of the solid/solution interface of minerals. The charging at different crystal faces depends on the surface chemical composition, that is, the type and number of proton-reactive surface groups. Atomic force microscopy has provided direct information on the pH-dependent

  20. CCl 4 chemistry on the magnetite selvedge of single-crystal hematite: competitive surface reactions

    Science.gov (United States)

    Adib, K.; Camillone, N., III; Fitts, J. P.; Rim, K. T.; Flynn, G. W.; Joyce, S. A.; Osgood, R. M., Jr.

    2002-01-01

    Temperature programmed reaction/desorption (TPR/D) studies were undertaken to characterize the surface chemistry which occurs between CCl 4 and the Fe 3O 4 (1 1 1) selvedge of single crystal α-Fe 2O 3 (0 0 0 1). Six separate desorption events are clearly observed and four desorbing species are identified: CCl 4, OCCl 2, C 2Cl 4 and FeCl 2. It is proposed that OCCl 2, CCl 4 and C 2Cl 4 are produced in reactions involving the same precursor, CCl 2. Three reaction paths compete for the CCl 2 precursor: oxygen atom abstraction (for OCCl 2), molecular recombinative desorption (for CCl 4) and associative desorption (for C 2Cl 4). During the TPR/D temperature ramp, the branching ratio is observed to depend upon temperature and the availability of reactive sites. The data are consistent with a rich site-dependent chemistry.

  1. Final Report - Independent Confirmatory Survey Summary and Results for the Hematite Decommissioning Project, Festus, Missouri

    International Nuclear Information System (INIS)

    Bailey, E.N.

    2009-01-01

    The objectives of the confirmatory surveys were to provide independent contractor field data reviews and to generate independent radiological data for use by the NRC in evaluating the adequacy and accuracy of the licensee's procedures and survey results.

  2. Studies on the use of the hematitic heavy concrete in the shielding of nuclear reactors

    International Nuclear Information System (INIS)

    Mello, M.J. de.

    1980-12-01

    The main difficulties and and the necessary adaptations in the usual techniques for the regular concrete, are intended to show. In particular the problems of dosing and the methods of vibration an homogenization in the setting of heavy concrete will need more detailed research. It was showed possible to obtain densities of 4 g/cm 3 and more. The atenuation coeficients obtained for the range of energy of gamma rays studied are much greater than the ones obtained with most concretes. The interpretation of measurements of these coeficients showed agreement with the characteristics of the materials and measuring methods used. The matching of the measured atenuation coeficients with the values calculated from the analysis of the mean composition of the heavy concrete also showed coherence with a deviation of 4% in most cases. (Author) [pt

  3. Facial synthesis of porous hematite supported Pt catalyst and its photo enhanced electrocatalytic ethanol oxidation performance

    International Nuclear Information System (INIS)

    Kang, Shuai; Shen, Pei Kang

    2015-01-01

    Graphical Abstract: A porous α-Fe 2 O 3 supported Pt catalyst has been synthesized by a facial thermal treatment assisted precipitation method and the materials show a illumination enhanced performance for ethanol oxidation. Display Omitted -- Highlights: •A porous α-Fe 2 O 3 supported Pt catalyst has been synthesized for the first time. •With the addition of α-Fe 2 O 3 , the current density of Pt/C grows about 51% under illumination and 32% in the dark compared with unsupported catalyst. •The current increases under illuminationin chronoamperometric experiments at a given potential of 0.7 V due to the photons from light provide energy for CO stripping. •This work demostrates an optical strategy to accelerate electrode reactions towards ethanol oxidation reaction. -- Abstract: The porous α-Fe 2 O 3 supported Pt catalyst is synthesized by a facial thermal treatment assisted precipitation method. The particle size of Pt is less than 3 nm. The pore diameters of α-Fe 2 O 3 particles are concentrated to 2.46 nm in a mesooporous scale. Its electrochemical performance is tested. The ethanol oxidation current of the Pt/Fe 2 O 3 catalsyt obviously improves under illumination, compared with that in the dark, during the optical switching operation. Moreover, with the addition of α-Fe 2 O 3 , the ethanol oxidation current of Pt/C grows about 51% under illumination and 32% in the dark; the onset potential shifts negtively for about 20 mV. This work demostrates an optical strategy which can be a potential alternative to accelerate electrode reactions towards ethanol oxidation reaction

  4. 78 FR 52574 - Westinghouse Electric Company, LLC; Decommissioning Project; Hematite, Missouri

    Science.gov (United States)

    2013-08-23

    ... request is granted, including the identity of any expert, consultant, or assistant who will aid the... shown by reliance on a qualified expert, consultant, or assistant who satisfies these criteria. (b) A... requests for access to SUNSI or SGI, and motions for protective orders, in a timely fashion in order to...

  5. 77 FR 16077 - License Amendment Request From Westinghouse Electric Company, LLC, Hematite Decommissioning Project

    Science.gov (United States)

    2012-03-19

    ... request is granted, including the identity of any expert, consultant, or assistant who will aid the... party or its counsel may be shown by reliance on a qualified expert, consultant, or assistant who... timely fashion in order to minimize any unnecessary delays in identifying those petitioners who have...

  6. Oxygen Evolution at Hematite Surfaces: The Impact of Structure and Oxygen Vacancies on Lowering the Overpotential

    NARCIS (Netherlands)

    Zhang, X.; Klaver, P.; van Santen, R.; van de Sanden, M. C. M.; Bieberle, A.

    2016-01-01

    Simulations of the oxygen evolution reaction (OER) are essential for understanding the limitations of water splitting. Most research has focused so far on the OER at flat metal oxide surfaces. The structure sensitivity of the OER has, however, recently been highlighted as a promising research

  7. Influence of Surface Effects on Magnetic Behavior of Hematite Nanoparticles Embedded in Porous Silica Matrix

    Czech Academy of Sciences Publication Activity Database

    Zeleňák, V.; Zeleňáková, A.; Kováč, J.; Vainio, U.; Murafa, Nataliya

    2009-01-01

    Roč. 113, č. 30 (2009), s. 13045-13050 ISSN 1932-7447 Institutional research plan: CEZ:AV0Z40320502 Keywords : drug-delivery * gamma-Fe2O3 nanoparticles Subject RIV: CA - Inorganic Chemistry Impact factor: 4.224, year: 2009

  8. Morphology-Controlled Synthesis of Hematite Nanocrystals and Their Optical, Magnetic and Electrochemical Performance

    Science.gov (United States)

    Li, Bangquan; Sun, Qian; Fan, Hongsheng; Cheng, Ming; Shan, Aixian; Cui, Yimin; Wang, Rongming

    2018-01-01

    A series of α-Fe2O3 nanocrystals (NCs) with fascinating morphologies, such as hollow nanoolives, nanotubes, nanospindles, and nanoplates, were prepared through a simple template-free hydrothermal synthesis process. The results showed that the morphologies could be easily controlled by SO42− and H2PO4−. Physical property analysis showed that the α-Fe2O3 NCs exhibited shape- and size-dependent ferromagnetic and optical behaviors. The absorption band peak of the α-Fe2O3 NCs could be tuned from 320 to 610 nm. Furthermore, when applied as electrode material for supercapacitor, the hollow olive-structure exhibited the highest capacitance (285.9 F·g−1) and an excellent long-term cycling stability (93% after 3000 cycles), indicating that it could serve as a candidate electrode material for a supercapacitor. PMID:29342929

  9. Interactions between humic acid and hematite and their effects on metal ion speciation

    NARCIS (Netherlands)

    Vermeer, A.W.P.

    1996-01-01


    The impact of toxic chemicals (like metal ions) on the environment is a phenomenon that has been recognised as a mayor problem over the last decades. The speciation of these chemicals determines whether or not a contaminated site has to be regarded as dangerous. The fate of the

  10. 77 FR 65910 - Westinghouse Electric Company, LLC., Hematite Decommissioning Project, Festus, Missouri

    Science.gov (United States)

    2012-10-31

    ... information previously available; and (iii) the filing has been submitted in a timely fashion based on the... proceeding may, in the discretion of the presiding officer, be permitted to make a limited appearance...

  11. 2011 Georgia Department of Natural Resources (GADNR) Environmental Protection Division (EPD) Lidar: Seven Counties (Bibb, Harris, Heard, Jasper, Jones, Monroe, Walton)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set is the topographic elevation point data derived from multiple return light detection and ranging (LiDAR) measurements for seven counties in Georgia....

  12. On the improvement of PEC activity of hematite thin films deposited by high-power pulsed magnetron sputtering method

    Czech Academy of Sciences Publication Activity Database

    Kment, Š.; Hubička, Zdeněk; Krysa, C.; Sekora, D.; Zlámal, M.; Olejníček, Jiří; Čada, Martin; Kšírová, Petra; Remeš, Zdeněk; Schmuki, P.; Schubert, E.; Zbořil, R.

    2015-01-01

    Roč. 165, Apr (2015), s. 344-350 ISSN 0926-3373 R&D Projects: GA ČR GAP108/12/2104; GA MŠk LH12043 Institutional support: RVO:68378271 Keywords : ALD * HiPIMS * passivation layer * photoelectrochemical water splitting * very thin films Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 8.328, year: 2015

  13. Study of the structural and magnetic properties of metallic iron-hematite particles for use in magnetorheological fluids

    Energy Technology Data Exchange (ETDEWEB)

    Osorio Ospina, Diana Marcela; Castro Navas, Irvin Jadway [Universidad del Valle, Escuela de Ingenieria de Materiales (Colombia); Perez Alcazar, German Antonio; Tabares, Jesus Anselmo, E-mail: jesus_tabares_8@hotmail.com [Universidad del Valle, Departamento de Fisica (Colombia)

    2012-03-15

    Magnetorheological (MR) fluids are new iron-based materials, whose applications include brakes, dampers, clutches, shock absorbers systems and polishing of optical surfaces (lens and mirrors). They are dependent on the size and shape of particles as the magnetic properties. Interested in the possibility of using iron-rich powders, commonly used in nondestructive testing, ranging in size from a few {mu}m to about 200 {mu}m and lower cost than those commercially used for MR fluids, a study of the structural and magnetic properties of iron-rich metallic particles by X-ray diffraction (XRD) and Moessbauer spectroscopy (MS) at room temperature has been done. Powders, as received, were separated into particle sizes smaller than 20 {mu}m (sample A) and in the range of 20-38 {mu}m (sample B) because these are the sizes generally required for applications in MR fluids. The particles whose sizes exceed the above values were ground in a high energy planetary mill for 3 h, using different values of rotational speed/time: 200 rpm for one hour, a pause of 10 s, 140 rpm for one hour, pause 10 s and then 175 rpm during the last hour. These powders were sieved to obtain particles smaller than 20 {mu}m (sample C). According XRD results, in all samples, only {alpha}-Fe (lattice parameter a = 2,867(2) Angstrom-Sign ) and Fe{sub 2}O{sub 3} (lattice parameter a 5,037(1) Angstrom-Sign and c = 13,755(8) Angstrom-Sign ) were present. The Moessbauer spectra were fitted with two sextets. The hyperfine parameters values allowed us to assign the highest relative area spectrum (sextet) corresponding to {alpha}-Fe and the second one to Fe{sub 2}O{sub 3} in accord to the XRD results. Thus, the preparation method using mechanical milling for diminishing the size of the metallic particles allowed us to get particles with size and magnetic properties that could lead to potentially MR fluids applications.

  14. Oxygen-deficient hematite nanorods as high-performance and novel negative electrodes for flexible asymmetric supercapacitors.

    Science.gov (United States)

    Lu, Xihong; Zeng, Yinxiang; Yu, Minghao; Zhai, Teng; Liang, Chaolun; Xie, Shilei; Balogun, Muhammad-Sadeeq; Tong, Yexiang

    2014-05-21

    Oxygen-deficient α-Fe2 O3 nanorods with outstanding capacitive performance are developed and demonstrated as novel negative electrodes for flexible asymmetric supercapacitors. The asymmetric-supercapacitor device based on the oxygen-deficient α-Fe2 O3 nanorod negative electrode and a MnO2 positive electrode achieves a maximum energy density of 0.41 mW·h/cm(3) ; it is also capable of charging a mobile phone and powering a light-emitting diode indicator. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Study of the structural and magnetic properties of metallic iron-hematite particles for use in magnetorheological fluids

    International Nuclear Information System (INIS)

    Osorio Ospina, Diana Marcela; Castro Navas, Irvin Jadway; Pérez Alcázar, German Antonio; Tabares, Jesus Anselmo

    2012-01-01

    Magnetorheological (MR) fluids are new iron-based materials, whose applications include brakes, dampers, clutches, shock absorbers systems and polishing of optical surfaces (lens and mirrors). They are dependent on the size and shape of particles as the magnetic properties. Interested in the possibility of using iron-rich powders, commonly used in nondestructive testing, ranging in size from a few μm to about 200 μm and lower cost than those commercially used for MR fluids, a study of the structural and magnetic properties of iron-rich metallic particles by X-ray diffraction (XRD) and Mössbauer spectroscopy (MS) at room temperature has been done. Powders, as received, were separated into particle sizes smaller than 20 μm (sample A) and in the range of 20–38 μm (sample B) because these are the sizes generally required for applications in MR fluids. The particles whose sizes exceed the above values were ground in a high energy planetary mill for 3 h, using different values of rotational speed/time: 200 rpm for one hour, a pause of 10 s, 140 rpm for one hour, pause 10 s and then 175 rpm during the last hour. These powders were sieved to obtain particles smaller than 20 μm (sample C). According XRD results, in all samples, only α-Fe (lattice parameter a = 2,867(2) Å) and Fe 2 O 3 (lattice parameter a 5,037(1) Å and c = 13,755(8) Å) were present. The Mössbauer spectra were fitted with two sextets. The hyperfine parameters values allowed us to assign the highest relative area spectrum (sextet) corresponding to α-Fe and the second one to Fe 2 O 3 in accord to the XRD results. Thus, the preparation method using mechanical milling for diminishing the size of the metallic particles allowed us to get particles with size and magnetic properties that could lead to potentially MR fluids applications.

  16. Particle size and kind of mica in synthesis of nontoxic bronze and gold pearlescent pigments based on nanoencapsulated hematite

    Directory of Open Access Journals (Sweden)

    Maryam Hosseini-Zori

    2015-12-01

    Full Text Available Nano-encapsulated iron oxide in Zirconium oxide-coated mica pigments are thermally stable,innocuous to human health, non-combustible, and they do not conduct electricity. They could beapplied in several industries such as thermoplastics, cosmetics, food packaging, children toys, paints,automobiles coating, security purposes, and banknotes. Nowadays, they are highly desirable inceramic decoration. In the present study, intensively dark gold to bronze colored mica clay pigments,which were based on mica flakes covered with a layer of nano-iron oxide-Zirconium oxide particles,were prepared by homogeneous precipitation of iron nitrate and Zirconium chloride ammonia in thepresence of mica flakes in two kinds of ore clay-based phlogopite and muscovite minerals. The finalcolor was obtained by thermal annealing of precipitates at a temperature of 800◦C. The pigments werecharacterized by X-Ray Diffraction, Particle size analysis, Scanning electron microscopy,Transmission electron microscopy, X-Ray fluorescence, and Simultaneous thermal analysis. Resultsindicate that nano-encapsulated iron oxide in zirconia particles have been formed on mica flakes andkinds of clay-mica can be related to obtained shade from dark gold to bronze pearl. Higher particlesize of mica flakes about phlogopite type of mica introduced pearl effects with higher L* changes indifferent angles. Muscovite performed higher hue and better pearl effect than phlogopite.

  17. Sorption of phosphate and zinc onto hematite and magnetite as mechanism of attenuation of contamination in agricultural soils

    OpenAIRE

    Martínez Martínez, María del Rosario; Martí, Vicens; Giménez Izquierdo, Francisco Javier

    2014-01-01

    Excess of natural and synthetic fertilizers applied to agricultural soils is a well-known source of contamination of nitrates and potential source of contamination of metals (copper and zinc) and phosphates (Alloway 2010). Mineral phases such as iron oxides, are present in agricultural soils and they might play a main role in the retardation of the transport of different contaminants (Giménez et al. 2007). The present communication shows the experimental study of sorption of phosp...

  18. Comparison of Micro- and Nanoscale Fe+3-Containing (Hematite) Particles for Their Toxicological Properties in Human Lung Cells In Vitro

    NARCIS (Netherlands)

    Bhattacharya, K.; Hoffmann, E.; Schins, R.F.P.; Boertz, J.; Prantl, E.M.; Alink, G.M.; Byrne, H.J.; Kuhlbusch, T.A.J.; Rahman, Q.; Wiggers, H.; Schulz, C.; Dopp, E.

    2012-01-01

    The specific properties of nanoscale particles, large surface-to-mass ratios and highly reactive surfaces, have increased their commercial application in many fields. However, the same properties are also important for the interaction and bioaccumulation of the nonbiodegradable nanoscale particles

  19. Synthesis and characterization of pigments of hematite, obtained through a by-product of the siderurgy industry

    International Nuclear Information System (INIS)

    Prim, S.R.; Folgueiras, M.V.; Lima, M.A. de

    2009-01-01

    In the ceramic industry of tooting, whose selection is strongly influenced by the visual aspect of the decorated surface, the color becomes one of the most important characteristic for the too tings. With the purpose of seeking new pigments that replace or optimize the already known, news method to synthesis are being researched, such as new pigments system and also the incorporation of new raw materials. In this form, in the present work search to study the possibility of use of a by-product deriving from of the siderurgical industry, that introduces high grades of the Fe 2 O 3 . For that different contests of the residue were added in one matrix of silica in the hape of quartz, and homogenized using conventional milling and high energy milling. The material obtained after heating treatment in temperature that varied between 1050 and 1300 deg C was characterization by x-ray diffractometry, differential thermal analysis and scanning electron microscopy. The results shown the feasibility of the process depend of the control of the variables temperature and condition of milling in the quality of material obtained. (author)

  20. Lithic assemblages of Azokh Cave (Nagorno Karabagh, Lesser Caucasus: Raw materials, technology and regional context

    Directory of Open Access Journals (Sweden)

    Lena Asryan

    2014-03-01

    Full Text Available Azokh Cave is a Middle Pleistocene to Holocene site located in Nagorno Karabagh (Lesser Caucasus. The main entrance, Azokh 1, is a large cave that has two geological sequences (lower and upper with nine geo-archaeological units of which only the upper ones (Units I to V have a significant archaeological record.  The faunal remains and lithic artefacts in these units indicate aspects of human occupation, and exploitation of, and association with animals.     The lithic artefacts presented here were recovered from Units V, III and II during the 2002 – 2009 excavation seasons. The available chronological data indicates an age between 293 – 100 Ka for these units. The operational chain is incomplete and artefacts found in the cave are primarily end-products dominated by flake-tools. The assemblage of Unit V is composed primarily of simple, unretouched flakes with a minimal presence of retouched flakes and cores. The Unit II lithic assemblage includes a substantial Levallois component, although with fewer cores and retouched flakes. There are very few flake tools in Unit III. While it is still difficult to assign the Unit V assemblage to a techno-typological group or complex (i.e. Acheulean, Mousterian or other local techno-complexes such as the Kudarian, the Unit II assemblage is clearly associated with Mode 3 or the Mousterian techno-complex.Different local and non-local raw materials were exploited in all units for the production of lithic artefacts, although the range of raw materials is more varied in Unit II. Local chert, flint and basalt were used most commonly, probably due to their easy accessibility. Limestone, jasper and sandstone, from local and non-local sources, are present in small quantities in Units V and II. Obsidian is the only raw material that possibly originates from more distant sources. Flint and chert appear to have been preferentially exploited for flake tool production in all units, but the toolmakers show a

  1. The role of sedimentology, oceanography, and alteration on the δ56Fe value of the Sokoman Iron Formation, Labrador Trough, Canada

    Science.gov (United States)

    Raye, Urmidola; Pufahl, Peir K.; Kyser, T. Kurtis; Ricard, Estelle; Hiatt, Eric E.

    2015-09-01

    The Sokoman Formation is a ca. 100-m-thick succession of interbedded iron formation and fine-grained siliciclastics deposited at 1.88 Ga. Accumulation occurred on a dynamic paleoshelf where oxygen stratification, coastal upwelling of hydrothermally derived Fe and Si, microbial processes, tide and storm currents, diagenesis, and low-grade prehnite-pumpellyite metamorphism controlled lithofacies character and produced complex associations of multigenerational chert, hematite, magnetite, greenalite, stilpnomelane and Fe carbonate. Hematite-rich facies were deposited along suboxic segments of the coastline where photosynthetic oxygen oases impinged on the seafloor. Hematitic, cross-stratified grainstones were formed by winnowing and reworking of freshly precipitated Fe-(oxyhydr)oxide and opal-A by waves and currents into subaqueous dunes. Magnetite-rich facies contain varying proportions of greenalite and stilpnomelane and record deposition in anoxic middle shelf environments beneath an oxygen chemocline. Minor negative Ce anomalies in hematitic facies, but prominent positive Ce and Eu anomalies and high LREE/HREE ratios in magnetite-rich facies imply the existence of a weakly oxygenated surface ocean above anoxic bottom waters. The Fe isotopic composition of 31 whole rock (-0.46 ⩽ δ56Fe ⩽ 0.47‰) and 21 magnetite samples (-0.29 ⩽ δ56Fe ⩽ 0.22‰) from suboxic and anoxic lithofacies was controlled primarily by the physical oceanography of the paleoshelf. Despite low-grade metamorphism recorded by the δ18O values of paragenetically related quartz and magnetite, the Sokoman Formation preserves a robust primary Fe isotopic signal. Coastal upwelling is interpreted to have affected the isotopic equilibria between Fe2+aq and Fe-(oxyhydr)oxide in open marine versus coastal environments, which controlled the Fe isotopic composition of lithofacies. Unlike previous work that focuses on microbial and abiotic fractionation processes with little regard for

  2. Textural and Isotopic Evidence for Silica Cementation in 1.88 GA Granular Iron Formation

    Science.gov (United States)

    Brengman, L. A.; Fedo, C.; Martin, W.

    2016-12-01

    Controls on quartz precipitation mechanisms and silicon isotope fractionation during diagenesis of Precambrian iron formation (IF) are not well constrained. The goal of this study is to identify textural evidence for the relative timing of silica cementation of granular units from the near un-metamorphosed 1.88 Ga Biwabik IF and determine the silicon isotope composition for such a silicification event. The lowermost IF (lower cherty, LC) consists of granular units associated with high-energy sedimentary structures interpreted to represent shallow-marine shelf deposition. Up-section is marked by an abrupt shift to banded units interpreted as a transition to quiescent (deeper) water, followed by a return to granular textures and shallower conditions (upper cherty, UC). We first surveyed granular samples of the lower stromatolitic (LC) and upper oncolitic facies (UC) to identify sedimentary textures and cement. LC units consist of microquartz (chert), megaquartz, hematite, carbonate, and detrital quartz, chert, and quartz/Fe-oxide intraclastic material. In UC samples, space between granular material (hematite, magnetite, quartz ooids/intraclasts) is filled by mega-quartz cement, and cross-cutting mega-quartz veins. We targeted mega-quartz cement, and veins for δ30Si analysis via secondary ion mass spectrometry. The average measured δ30Si value of cement (δ30Siavg. cement UC6b = -3.11 ± 0.21 ‰) is significantly different than associated veins (δ30Siavg. vein UC6b = 0.21 ± 0.21 ‰; δ30Siavg. vein LC4 = 0.39 ± 0.21 ‰), both within and between samples. We interpret the relative difference between cement and veins to represent quartz precipitation under different geochemical conditions, and therefore at different times. Combining isotopic and textural evidence, we interpret silica cementation to pre-date veins, and represent quartz precipitation that either varied in rate, or occurred under closed-system conditions affected by Rayleigh distillation. Both

  3. Sedimentary and tectonic history of the Holowilena Ironstone, a Neoproterozoic iron formation in South Australia

    Science.gov (United States)

    Lechte, Maxwell Alexander; Wallace, Malcolm William

    2015-11-01

    The Holowilena Ironstone is a Neoproterozoic iron formation in South Australia associated with glacial deposits of the Sturtian glaciation. Through a comprehensive field study coupled with optical and scanning electron microscopy, X-ray fluorescence, and X-ray diffraction, a detailed description of the stratigraphy, sedimentology, mineralogy, and structure of the Holowilena Ironstone was obtained. The Holowilena Ironstone comprises ferruginous shales, siltstones, diamictites, and is largely made up of hematite and jasper, early diagenetic replacement minerals of precursor iron oxyhydroxides, and silica. These chemical precipitates are variably influenced by turbidites and debris flows contributing clastic detritus to the depositional system. Structural and stratigraphic evidence suggests deposition within a synsedimentary half-graben. A model for the Holowilena Ironstone is proposed, in which dense oxic fluids expelled during sea ice formation in the Cryogenian pool in the depression of the half-graben, allowing for long-lived mixing with the ferruginous seawater and the deposition of iron oxides. This combination of glacial dynamics, tectonism, and ocean chemistry may explain the return of iron formations in the Neoproterozoic.

  4. 75 FR 68377 - Notice of Inventory Completion: Anthropological Studies Center, Archaeological Collections...

    Science.gov (United States)

    2010-11-05

    ... associated funerary objects are 8 obsidian tools, 183 obsidian flakes, 30 chert flakes, 4 basalt flakes, 1... individuals were identified. The 54 associated funerary objects are 20 obsidian tools, 1 chert tool, 3...

  5. De la razón al juego: la teoría del conocimiento de la enfermedad en Karl Jaspers y su reconsideración desde la epistemología actual

    Directory of Open Access Journals (Sweden)

    González de Pablo, Ángel

    2002-06-01

    Full Text Available Starting with the idea of the Encompassing as a system of thinking, I have tried to describe a possible Jaspersian theory of the knowledge of illness. This theory is based on the following points: 1 The existence of two methods of knowledge of the sick person: the direct or objective (based on causality, non-contradiction, and the accuracy of language; and the indirect or unobjective (based on acausality, antinomy, and the polysemy of language. 2 The establishment of a non-syncretic articulation between the two through Reason (Vernunft. And 3 The consideration of the whole of the illness as a veiled reality, as a reality which is announced alternately in the two conected but not superimposed ways of knowing, although such a reality can never be enunciated in the form of a methodically fixed doctrine. The various points of this theory are reconsidered, in addition, from the point of view of certain concepts belonging to current epistemology, so as to evaluate the degree of presence of Jaspersian thought at the end of the 20th century.

    A partir de la idea del Envolvente en tanto sistemática del pensamiento, se intenta caracterizar una posible teoría jaspersiana del conocimiento de la enfermedad. Dicha teoría gira en torno a los siguientes puntos: 1 La existencia de dos modos de conocimiento del enfermar: el directo u objetivo (basado en la causalidad, la no contradicción y la univocidad del lenguaje; y el indirecto o inobjetivo (basado en la acausalidad, la antinomia y la polisemia del lenguaje. 2 El establecimiento de una articulación no sincrética entre ambos por intermedio de la Razón. y 3 La consideración del todo de la enfermedad como realidad velada, como realidad que se anuncia alternativamente en esos dos modos articulados y no superponibles de conocimiento, pero que —en su totalidad— no puede enunciarse objetivamente. Los distintos puntos de esta teoría se reconsideran, además, desde ciertas nociones de la actual teoría del conocimiento con el fin de conjeturar cuál podría ser la vigencia del pensamiento jaspersiano a finales del siglo XX.

  6. Amending Jasper County, Missouri soils with biochar and other amendments following chat removal to facilitate soil restoration/revitalization and establishment of a soil-stabilizing plant cover: An ORD and Region 7 Collaboration

    Science.gov (United States)

    Abandoned mines and the residuals from mining across the U.S. pose a considerable, pervasive risk to human health and the environment. Many soils in the Tri-State-Mining District (TSMD), located where Missouri, Kansas and Oklahoma meet, have been affected by the residuals of his...

  7. Betoonist videograafika / Helen Kivisoo

    Index Scriptorium Estoniae

    Kivisoo, Helen

    2001-01-01

    12. augustini Helsingis MUU galeriis Jasper Zoova videoinstallatsioon "Hebel - Betoonehitus uuest aspektist" ja Tuukka Kaila (Soome) fotod "Heissulivei - Vaadake kui ilus - Check out me and my country".

  8. Deposition of hematite Fe.sub.2./sub.O.sub.3./sub. thin film by DC pulsed magnetron and DC pulsed hollow cathode sputtering system

    Czech Academy of Sciences Publication Activity Database

    Hubička, Zdeněk; Kment, Štěpán; Olejníček, Jiří; Čada, Martin; Kubart, T.; Brunclíková, Michaela; Kšírová, Petra; Adámek, Petr; Remeš, Zdeněk

    2013-01-01

    Roč. 549, Dec (2013), s. 184-191 ISSN 0040-6090 R&D Projects: GA ČR GAP108/12/2104; GA MŠk LH12043 Grant - others:AVČR(CZ) M100101215 Institutional support: RVO:68378271 Keywords : HIPIMS * thin films * hollow cathode Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.867, year: 2013

  9. Investigations of electrical and optical properties of low energy ion irradiated α-Fe{sub 2}O{sub 3} (hematite) thin films

    Energy Technology Data Exchange (ETDEWEB)

    Sulania, Indra; Kanjilal, D. [Inter University Accelerator Centre, P O Box-10502, Aruna Asaf Ali Marg, New Delhi-110067 (India); Kaswan, Jyoti; Attatappa, Vinesh [Department of physics, Amity University, Manesar-122 413, Haryana (India); Karn, Ranjeet Kumar [Jamshedpur Cooperative College, Circuit House Area, Jamshedpur-831001, Jharkhand (India); Agarwal, D. C. [Sant Longowal Institute of Engineering and Technology, Sangrur, Longowal-148106, Punjab (India)

    2016-05-23

    Thin films of α-Fe{sub 2}O{sub 3} of thickness ~100 nm were synthesized on Si (100) and glass substrates by thermal evaporation method. The as deposited films were annealed at 400°C in Oxygen environment for 2 hours to obtain the desired phase. The annealed films found to be polycrystalline in nature with an average crystallite size ~7 nm. The direct and indirect band gaps were found to be 2.2 and 1.5 eV respectively for annealed films using. I-V characteristics and Hall-effect measurement of annealed films showed n-type semi conducting behavior. Further, films were irradiated with nitrogen ions of energy 10 keV at an ion fluence of 1×10{sup 18} ions/cm{sup 2}. After irradiation, a decrease in both direct as well as indirect band gap was observed, from 2.2 to 2.1 eV and 1.5 to 1.3 eV respectively. I-V characteristic and Hall-Effect measurement confirmed change in conductivity of the films from n-type to p-type after irradiation, which can have possible applications in semi conducting device fabrications.

  10. Facile fabrication of tin-doped hematite photoelectrodes - effect of doping on magnetic properties and performance for light-induced water splitting

    Czech Academy of Sciences Publication Activity Database

    Frydrych, J.; Machala, L.; Tuček, J.; Šišková, K.; Filip, J.; Pechoušek, J.; Šafářová, K.; Vondráček, Martin; Seo, J. H.; Schneeweiss, Oldřich; Grätzel, M.; Sivula, K.; Zbořil, R.

    2012-01-01

    Roč. 22, č. 43 (2012), s. 23232-23239 ISSN 0959-9428 R&D Projects: GA ČR GA106/08/1440; GA MŠk(CZ) LC06058 Institutional support: RVO:68081723 ; RVO:68378271 Keywords : Alpha-Fe203 thin-films * photoanodes * electrodes * nanostructures * oxides Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 5.968, year: 2011

  11. The interference of nuclear transitions in the purely nuclear diffraction of 14.4 keV gamma-rays in hematite

    International Nuclear Information System (INIS)

    Stepanov, E.P.; Artem'ev, A.N.; Perstnev, I.P.; Sklyarevskii, G.V.

    1975-01-01

    A new type of interference manifested by the interaction of recoilless gamma radiation with matter was studied, i.e., the interference between different transitions of the magnetic hyperfine structure in nuclear diffraction. The measurements were carried out using a Moessbauer diffractometer at room temperature. Gamma radiation from a 57 Fe in Cr source was scattered by an α-Fe 2 O 3 single crystal. Peak asymmetry of the velocity spectra was observed in all measured spectra. It was most marked in the central parts of the spectra. The interference term had the typical shape of a dispersion curve. The magnitude of asymmetry, i.e., the ratio of the dispersion curve amplitudes to the peak was about 5 %, its sign depending on the signs and magnitudes of all transitions in the spectrum. The magnitude of the interference term decreased with increasing the distance between resonances. Theoretical curves were in good agreement with the experimental spectra. (L.O.)

  12. Grain size dependent potential for self generation of magnetic anomalies on Mars via thermoremanent magnetic acquisition and magnetic interaction of hematite and magnetite

    Czech Academy of Sciences Publication Activity Database

    Kletetschka, Günther; Ness, F. N.; Connerney, J. E. P.; Acuna, M. H.; Wasilewski, P. J.

    2005-01-01

    Roč. 148, 2-4 (2005), s. 149-156 ISSN 0031-9201 Institutional research plan: CEZ:AV0Z30130516 Keywords : magnetic mineralogy * self-magnetization * blocking temperature * Martian crust Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.420, year: 2005

  13. Iron Oxide Films Prepared by Rapid Thermal Processing for Solar Energy Conversion

    DEFF Research Database (Denmark)

    Wickman, B.; da Silva Fanta, Alice Bastos; Burrows, Andrew

    2017-01-01

    Hematite is a promising and extensively investigated material for various photoelectrochemical (PEC) processes for energy conversion and storage, in particular for oxidation reactions. Thermal treatments during synthesis of hematite are found to affect the performance of hematite electrodes...

  14. Middle Palaeolithic technical behaviour: Material import-export and Levallois production at the SU 13 of Oscurusciuto rock shelter, Southern Italy

    Directory of Open Access Journals (Sweden)

    Giulia Marciani

    2016-09-01

    The main concept of debitage was Levallois, generally realized on local jasper and siliceous limestone pebbles or cortical flakes. Jasper and siliceous limestone flakes, backed flakes and convergent flakes were the technological objectives of the debitage. A marginal volumetric debitage aimed at producing bladelets was also attested.

  15. Alteration geochemistry of the volcanic-hosted Dedeninyurdu, Yergen and Fındıklıyar Fe-Cu mineralization at Gökçedoǧan, Çorum-Kargi region, Turkey

    Science.gov (United States)

    Gumus, Lokman; Öztürk, Sercan; Yalçın, Cihan; Abdelnasser, Amr; Hanilçi, Nurullah; Kumral, Mustafa

    2016-04-01

    This study is to determine the mass/volume gain and loss of the major and trace elements during the alteration processes on Dedeninyurdu, Yergen and Fındıklıyar Fe-Cu mineralizations of the area. Fe-Cu mineralization occurred in the spilitic volcanic a rock of Saraycık Formation is associated with the different types of alteration zones which are pyritization, silicification and sericitization. The study area comprises Bekirli Formation, Saraycık Formation, Beşpınar Formation, and Ilgaz Formation. Saraycık formation consists of spilitic volcanic rocks with pelagic limestone, siltstone and chert. The ore mineralogical data show that the pyrite, chalcopyrite, covellite, hematite, malachite and goethite formed during three phases of mineralization. As well as the geologic and petrographic studies reveal three alteration zones with definite mineral assemblages; phyllic alteration (quartz + sericite + pyrite) that represents the main alteration and mineralized zone; propylitic alteration; and carbonatized sericitic alteration zone. The boundaries between these zones are gradual. Mass balance calculations suggested that the phyllic alteration zone represented by gain in Si, Fe, K, S, and LOI and loss in Mg, Ca, and Na refers to silicification, sericitization and pyritization as well as replacement of Fe-Mg silicate and plagioclase. While, in the propylitic alteration zone, enrichment of Si, Fe, Mg, LOI and S occurred with depletions of Ca, Na, and K reflecting chloritization alteration type. On the other hand, carbonatized sericitic alteration zone shows local gain in Si, CaO and K reflects the occurrence of calc-silicate alteration. All alteration zones contain a large proportion of sulfide minerals (gain in S) with increase in loss on ignition (LOI). Keywords: Alteration geochemistry; Mass balance calculation, Fe-Cu mineralization; phyllic alteration, propylitic alteration.

  16. STRATIGRAPHY OF THE PB-1 WELL, NOPAL I URANIUM DEPOSIT, SIERRA PENA BLANCA, CHIHUAHUA, MEXICO

    Energy Technology Data Exchange (ETDEWEB)

    NA

    2005-06-25

    Three wells, PB-1, PB-2, and PB-3, were drilled in 2003 at the Nopal I uranium deposit as part of a natural analogue study to evaluate radionuclide transport processes. The wells penetrate through the Tertiary volcanic section down to the Cretaceous limestone basement, and intersect the top of the regional aquifer system. The PB-1 well, drilled immediately adjacent to the Nopal I ore body, was cored to a depth of 250 m, thus providing an opportunity to document the local stratigraphy. The uppermost unit encountered in the PB-1 well is the Nopal Formation, a densely welded, crystal-rich rhyolitic ash-flow tuff. The cored section is highly altered and devitrified, with kaolinite, quartz, chlorite, and montmorillonite replacing feldspars and much of the groundmass. Breccia zones within the tuff contain fracture fillings of hematite, limonite, and goethite. A zone of intense clay alteration encountered in the depth interval 17.45-22.30 m was interpreted to represent the basal vitrophyre of this unit. Underlying the basal vitrophyre is the Coloradas Formation, which consists of a welded, lithic-rich rhyolitic ash-flow tuff. The cored section of this unit has undergone devitrification and oxidation, and has a similar alteration mineralogy to that observed in the Nopal tuff. The Nopal I ore body is restricted to a brecciated zone that intersects these two volcanic units. A sharp contact between the Coloradas tuff and the underlying Pozos Formation was observed at a depth of 136.38 m. The Pozos Formation in the PB-1 core consists of interbedded, poorly sorted sandstone and conglomerate layers. The conglomeratic clasts consist of subangular to subrounded fragments of volcanic rocks, limestone, and chert. Thin (2-6 m) intervals of intercalated pumiceous tuffs were observed within this unit. The contact between the Pozos Formation and the underlying Cretaceous limestone basement was observed at a depth of 244.4 m.

  17. STRATIGRAPHY OF THE PB-1 WELL, NOPAL I URANIUM DEPOSIT, SIERRA PENA BLANCA, CHIHUAHUA, MEXICO

    International Nuclear Information System (INIS)

    2005-01-01

    Three wells, PB-1, PB-2, and PB-3, were drilled in 2003 at the Nopal I uranium deposit as part of a natural analogue study to evaluate radionuclide transport processes. The wells penetrate through the Tertiary volcanic section down to the Cretaceous limestone basement, and intersect the top of the regional aquifer system. The PB-1 well, drilled immediately adjacent to the Nopal I ore body, was cored to a depth of 250 m, thus providing an opportunity to document the local stratigraphy. The uppermost unit encountered in the PB-1 well is the Nopal Formation, a densely welded, crystal-rich rhyolitic ash-flow tuff. The cored section is highly altered and devitrified, with kaolinite, quartz, chlorite, and montmorillonite replacing feldspars and much of the groundmass. Breccia zones within the tuff contain fracture fillings of hematite, limonite, and goethite. A zone of intense clay alteration encountered in the depth interval 17.45-22.30 m was interpreted to represent the basal vitrophyre of this unit. Underlying the basal vitrophyre is the Coloradas Formation, which consists of a welded, lithic-rich rhyolitic ash-flow tuff. The cored section of this unit has undergone devitrification and oxidation, and has a similar alteration mineralogy to that observed in the Nopal tuff. The Nopal I ore body is restricted to a brecciated zone that intersects these two volcanic units. A sharp contact between the Coloradas tuff and the underlying Pozos Formation was observed at a depth of 136.38 m. The Pozos Formation in the PB-1 core consists of interbedded, poorly sorted sandstone and conglomerate layers. The conglomeratic clasts consist of subangular to subrounded fragments of volcanic rocks, limestone, and chert. Thin (2-6 m) intervals of intercalated pumiceous tuffs were observed within this unit. The contact between the Pozos Formation and the underlying Cretaceous limestone basement was observed at a depth of 244.4 m

  18. Ironstone deposits hosted in Eocene carbonates from Bahariya (Egypt)-New perspective on cherty ironstone occurrences

    Science.gov (United States)

    Afify, A. M.; Sanz-Montero, M. E.; Calvo, J. P.

    2015-11-01

    This paper gives new insight into the genesis of cherty ironstone deposits. The research was centered on well-exposed, unique cherty ironstone mineralization associated with Eocene carbonates from the northern part of the Bahariya Depression (Egypt). The economically important ironstones occur in the Naqb Formation (Early Eocene), which is mainly formed of shallow marine carbonate deposits. Periods of lowstand sea-level caused extensive early dissolution (karstification) of the depositional carbonates and dolomitization associated with mixing zones of fresh and marine pore-water. In faulted areas, the Eocene carbonate deposits were transformed into cherty ironstone with preservation of the precursor carbonate sedimentary features, i.e. skeletal and non-skeletal grain types, thickness, bedding, lateral and vertical sequential arrangement, and karst profiles. The ore deposits are composed of iron oxyhydroxides, mainly hematite and goethite, chert in the form of micro- to macro-quartz and chalcedony, various manganese minerals, barite, and a number of subordinate sulfate and clay minerals. Detailed petrographic analysis shows that quartz and iron oxides were coetaneous and selectively replaced carbonates, the coarse dolomite crystals having been preferentially transformed into quartz whereas the micro-crystalline carbonates were replaced by the iron oxyhydroxides. A number of petrographic, sedimentological and structural features including the presence of hydrothermal-mediated minerals (e.g., jacobsite), the geochemistry of the ore minerals as well as the structure-controlled location of the mineralization suggest a hydrothermal source for the ore-bearing fluids circulating through major faults and reflect their proximity to centers of magmatism. The proposed formation model can contribute to better understanding of the genetic mechanisms of formation of banded iron formations (BIFs) that were abundant during the Precambrian.

  19. 77 FR 19694 - Notice of Intent To Repatriate Cultural Items: U.S. Department of Defense, Army Corps of...

    Science.gov (United States)

    2012-04-02

    ... fragments; 1 projectile point; 1 projectile point base; 2 modified flakes; and 1 charcoal sample. According... charcoal/organic samples, 1 chert projectile point, 6 copper fragments, 1 piece of chert debitage, 3... iron and copper objects combined with a lack of glass trade beads. Human remains recovered from this...

  20. 77 FR 43116 - Notice of Inventory Completion: The University of Montana, Missoula, MT; Correction

    Science.gov (United States)

    2012-07-23

    ... were identified. The seven associated funerary objects are 1 copper bell, 1 set of copper beads, 1 copper coil, 1 shell pendant fragment, 1 set of arrow points, 1 set of lithic flakes, and 1 lot of beads... objects are 13 animal rib bones, 1 bird bone whistle, 1 chert flake, 1 chert tool, and 1 drill with a...

  1. Teise korruse filmid Kanuti Gildi saalis : Zoova, Säde ja Piibemann

    Index Scriptorium Estoniae

    2008-01-01

    Kanuti Gildi saali teisel korrusel filmiprogrammi "Teise korruse filmid" linastuvad täna Jasper Zoova filmid "Parallel Euro" ja "Armastuse barrikaadidel", Margit Säde "Failing Files", Taavi Piibemanni "Peategelased"

  2. Eesti ja Soome kunstniku ühisnäitus Helsingis

    Index Scriptorium Estoniae

    2001-01-01

    24. juulist 12. augustini on Helsingis MUU galeriis avatud Jasper Zoova videoinstallatsiooni "Hebel - betoonehitus uuest aspektist" ja soome kunstniku Tuukka Kaila fotode näitus "Heissulivei - Vaadake kui ilus - Check Out Me and My Coutry"

  3. Sõna on autoril / Siram

    Index Scriptorium Estoniae

    Siram, pseud., 1968-

    2011-01-01

    Mare Tralla isikunäitus "Autoportreed" Pärnu Kunstnike Majas 18. juunini 2011, kultuuriõhtu "Olemasolu variatsioonid" 11. juunil: Kiwa ja Terje Toomistu filmi "Wariazone" Pärnu esilinastus ning Jasper Zoova autoraamatu esitlus

  4. Noorte kunst Frankfurdis

    Index Scriptorium Estoniae

    1999-01-01

    26. X avati Frankfurdis eesti noorte kunstnike vahetusnäitus 'Lääne-ida diivan'. Osalevad Killu Sukmit, Kadi Soosalu, Margot Kask, Piia Ruber, Mirja-Mari Smidt, Jasper Zoova, Marko Laimre, Kiwa, Taave Tuutma. Kuraator Mari Laanemets.

  5. Kevad Veneetsias / Peeter Pere

    Index Scriptorium Estoniae

    Pere, Peeter, 1957-

    2013-01-01

    Arhitektuuriga haakuvatest töödest 55. Venezia biennaalil. Walter de Maria (USA), Robert Goberi (USA), Andra Ursuta (Rumeenia), Jasper Justi (Taani), Lara Almarcequi (Hispaania) ja Dénes Farkase (Eesti) töödest

  6. Kolm raamistikku Mäetamme unenäole / Katrin Kivimaa

    Index Scriptorium Estoniae

    Kivimaa, Katrin, 1969-

    2007-01-01

    Marko Mäetamme teosest "Kaotaja paradiis" Veneetsia biennaalil 2007. aastal. Kuraator Mika Hannula. S. Freudi unenägude käsitlusest. Inglise kunstiajaloolane Fred Orton ameerika kunstniku Jasper Johnsi tööst "Lipp"

  7. Eesti noor kunst Helsingis, Riias ja Londonis

    Index Scriptorium Estoniae

    2000-01-01

    Ester Faimani, Jasper Zoova ja Tarrvi Laamanni ühisnäitus "Splendid!? Young art from Estonia" Helsingis Caisa kultuurikeskuses, kuraator Andres Härm ; Kiwa videokunst Riias Arsenals Museumis ja Londonis Milch Gallery's

  8. Kunstnikele tasuta monitorid / Kirsti Vainküla

    Index Scriptorium Estoniae

    Vainküla, Kirsti, 1972-

    1998-01-01

    Ideegrupp Interface jagas 10-le eesti kunstnikule arvutimonitorid, mille need kunstiliselt kujundavad. Monitori said Agur Kruusing, Marko Mäetamm, Kaido Ole, Martin Pedanik, Urmas Puhkan, Jüri Roosa, Jasper Zoova

  9. 47 CFR 90.614 - Segments of the 806-824/851-869 MHz band for non-border areas.

    Science.gov (United States)

    2010-10-01

    ..., Henry, Houston, Jackson, Jefferson, Lamar, Lauderdale, Lawrence, Lee, Limestone, Lowndes, Macon, Madison..., Greene, Gwinnett, Habersham, Hall, Hancock, Haralson, Harris, Hart, Heard, Henry, Houston, Irwin, Jackson, Jasper, Jeff Davis, Jefferson, Jenkins, Johnson, Jones, Lamar, Lanier, Laurens, Lee, Liberty, Lincoln...

  10. Culex coronator in coastal Georgia and South Carolina.

    Science.gov (United States)

    Moulis, Robert A; Russell, Jennifer D; Lewandowski, Henry B; Thompson, Pamela S; Heusel, Jeffrey L

    2008-12-01

    In 2007, adult Culex coronator were collected in Chatham County, Georgia, and Jasper County, South Carolina, during nuisance and disease vector surveillance efforts. A total of 75 specimens of this species were collected at 8 widely separated locations in Chatham County, Georgia, and 4 closely situated sites in Jasper County, South Carolina. These represent the first Atlantic coastal records of this species in Georgia and the first confirmed records of Cx. coronator in South Carolina.

  11. Synthesis and characterization of pigments of hematite, obtained through a by-product of the siderurgy industry; Sintese e caracterizacao de pigmento de hematita, obtido atraves de um subproduto da industria siderurgica

    Energy Technology Data Exchange (ETDEWEB)

    Prim, S.R.; Folgueiras, M.V.; Lima, M.A. de, E-mail: dem6srp@joinville.udesc.b [Universidade Estadual de Santa Catarina (PGCEM/UDESC), Joinville, SC (Brazil). Programa de Pos-Graduacao em Ciencia e Engenharia de Materiais

    2009-07-01

    In the ceramic industry of tooting, whose selection is strongly influenced by the visual aspect of the decorated surface, the color becomes one of the most important characteristic for the too tings. With the purpose of seeking new pigments that replace or optimize the already known, news method to synthesis are being researched, such as new pigments system and also the incorporation of new raw materials. In this form, in the present work search to study the possibility of use of a by-product deriving from of the siderurgical industry, that introduces high grades of the Fe{sub 2}O{sub 3}. For that different contests of the residue were added in one matrix of silica in the hape of quartz, and homogenized using conventional milling and high energy milling. The material obtained after heating treatment in temperature that varied between 1050 and 1300 deg C was characterization by x-ray diffractometry, differential thermal analysis and scanning electron microscopy. The results shown the feasibility of the process depend of the control of the variables temperature and condition of milling in the quality of material obtained. (author)

  12. Reply to the comment on the paper 'Grain size dependent potential for self generation of magnetic anomalies on Mars via thermoremanent magnetic acquisition and magnetic interaction of hematite and magnetite'

    Czech Academy of Sciences Publication Activity Database

    Kletetschka, Günther

    2006-01-01

    Roč. 159, 1-2 (2006), s. 127-128 ISSN 0031-9201 Institutional research plan: CEZ:AV0Z30130516 Keywords : magnetization * modeling * modeled data Subject RIV: DB - Geology ; Mineralogy Impact factor: 2.440, year: 2006

  13. Modern rather than Mesoarchaean oxidative weathering responsible for the heavy stable Cr isotopic signatures of the 2.95 Ga old Ijzermijn iron formation (South Africa)

    Science.gov (United States)

    Albut, Gülüm; Babechuk, Michael G.; Kleinhanns, Ilka C.; Benger, Manuela; Beukes, Nicolas J.; Steinhilber, Bernd; Smith, Albertus J. B.; Kruger, Stephanus J.; Schoenberg, Ronny

    2018-05-01

    Previously reported stable Cr isotopic fractionation in Archaean paleosols and iron formations (IFs) have been interpreted as a signature of oxidative weathering of Cr(III) to Cr(VI) in soils, and delivery of isotopically heavy Cr(VI) into the oceans. One of the oldest reported fingerprints of this process is isotopically heavy Cr preserved in the 2.95 Ga old Ijzermijn IF, Sinqeni Formation of the Mozaan Group (Pongola Supergroup), South Africa and could suggest that atmospheric free oxygen was present ca. 600 million years earlier than the Great Oxidation Event (GOE). However, fractionated stable Cr isotopic signatures have only been found to date in surface outcrop samples of the White Mfolozi Inlier exposed along the White Mfolozi River Gorge. In this study, the latter outcrop was resampled along with two drill cores of the Ijzermijn IF and a drill core of the Scotts Hill IF to represent multiple exposures of Mozaan Group IFs with different states of preservation. A detailed geochemical comparison on bulk samples of different units was undertaken using stable Cr isotopes coupled with trace and major elements. Outcrop iron-rich mudstones (Fe - lutites) show very low LOI [wt] %, and very low Fe(II)/Fetot ratios, and lower Ca and Mg relative to equivalent facies in drill cores, indicating the effects that oxidative recent surface weathering had on Fe/Mn-rich carbonate minerals of the IF. Overall rare earth element and yttrium (REE + Y) mixing models agree well with previous studies, confirming that they were minimally disturbed by weathering and are consistent with a high magnitude of continental solutes delivered in a near-shore depositional environment, with a minor contribution of hydrothermally derived fluids that upwelled into shallower depositional setting. Importantly, all drill core samples of this study revealed δ53/52Cr values within the igneous inventory, despite variable amounts of detrital Cr input that includes nearly detritus-free, chert/jasper

  14. Potentiometric Surfaces in the Springfield Plateau and Ozark Aquifers of Northwestern Arkansas, Southeastern Kansas, Southwestern Missouri, and Northeastern Oklahoma, 2006

    Science.gov (United States)

    Gillip, Jonathan A.; Czarnecki, John B.; Mugel, Douglas N.

    2008-01-01

    The Springfield Plateau and Ozark aquifers are important sources of ground water in the Ozark Plateaus aquifer system. Water from these aquifers is used for agricultural, domestic, industrial, and municipal water sources. Changing water use over time in these aquifers presents a need for updated potentiometric-surface maps of the Springfield Plateau and Ozark aquifers. The Springfield Plateau aquifer consists of water-bearing Mississippian-age limestone and chert. The Ozark aquifer consists of Late Cambrian to Middle Devonian age water-bearing rocks consisting of dolostone, limestone, and sandstone. Both aquifers are complex with areally varying lithologies, discrete hydrologic units, varying permeabilities, and secondary permeabilities related to fractures and karst features. During the spring of 2006, ground-water levels were measured in 285 wells. These data, and water levels from selected lakes, rivers, and springs, were used to create potentiometric-surface maps for the Springfield Plateau and Ozark aquifers. Linear kriging was used initially to construct the water-level contours on the maps; the contours were subsequently modified using hydrologic judgment. The potentiometric-surface maps presented in this report represent ground-water conditions during the spring of 2006. During the spring of 2006, the region received less than average rainfall. Dry conditions prior to the spring of 2006 could have contributed to the observed water levels as well. The potentiometric-surface map of the Springfield Plateau aquifer shows a maximum measured water-level altitude within the study area of about 1,450 feet at a spring in Barry County, Missouri, and a minimum measured water-level altitude of 579 feet at a well in Ottawa County, Oklahoma. Cones of depression occur in Dade, Lawrence and Newton Counties in Missouri and Delaware and Ottawa Counties in Oklahoma. These cones of depression are associated with private wells. Ground water in the Springfield Plateau aquifer

  15. Mineralogical and geochemical characteristics of the Noamundi-Koira basin iron ore deposits (India)

    Science.gov (United States)

    Mirza, Azimuddin; Alvi, Shabbar Habib; Ilbeyli, Nurdane

    2015-04-01

    India is one of the richest sources of iron ore deposits in the world; and one of them is located in the Noamundi-Koira basin, Singhbhum-Orissa craton. The geological comparative studies of banded iron formation (BIF) and associated iron ores of Noamundi-Koira iron ore deposits, belonging to the iron ore group in eastern India, focus on the study of mineralogy and major elemental compositions along with the geological evaluation of different iron ores. The basement of the Singhbhum-Orissa craton is metasedimentary rocks which can be traced in a broadly elliptical pattern of granitoids, surrounded by metasediments and metavolcanics of Greenstone Belt association. The Singhbhum granitoid is intrusive into these old rocks and to younger, mid Archaean metasediments, including iron formations, schists and metaquartzites and siliciclastics of the Precambrian Iron Ore Group (Saha et al., 1994; Sharma, 1994). The iron ore of Noamundi-Koira can be divided into seven categories (Van Schalkwyk and Beukes 1986). They are massive, hard laminated, soft laminated, martite-goethite, powdery blue dust and lateritic ore. Although it is more or less accepted that the parent rock of iron ore is banded hematite jasper (BHJ), the presence of disseminated martite in BHJ suggests that the magnetite of protore was converted to martite. In the study area, possible genesis of high-grade hematite ore could have occurred in two steps. In the first stage, shallow, meteoric fluids affect primary, unaltered BIF by simultaneously oxidizing magnetite to martite and replacing quartz with hydrous iron oxides. In the second stage of supergene processes, deep burial upgrades the hydrous iron oxides to microplaty hematite. Removal of silica from BIF and successive precipitation of iron resulted in the formation of martite- goethite ore. Soft laminated ores were formed where precipitation of iron was partial or absent. The leached out space remains with time and the interstitial space is generally filled

  16. 75 FR 58432 - Notice of Inventory Completion: U.S. Army Corps of Engineers, Portland District, Portland, OR and...

    Science.gov (United States)

    2010-09-24

    ...,182 associated funerary objects are 41 projectile points, 8 projectile point fragments, 2 chert... eastern flanks of the Cascade Range and the lower reaches of the Yakima River drainage. Officials of the U...

  17. 78 FR 37843 - Notice of Intent To Prepare an Environmental Impact Statement for the Proposed Panels F and G...

    Science.gov (United States)

    2013-06-24

    ... existing haul road and would deviate only where engineering constraints dictate (i.e., too tight a corner... 20 acres for the temporary storage of chert to be used for reclamation; and (3) utilization of a geo...

  18. Bavorské jurské rohovce Franské Alby v neolitu a eneolitu Čech

    Czech Academy of Sciences Publication Activity Database

    Burgert, Pavel

    2016-01-01

    Roč. 68, č. 1 (2016), s. 91-108 ISSN 0323-1267 Institutional support: RVO:67985912 Keywords : Neolithic * Eneolithic * Bohemia * chipped stone industry * Bavarian Jurassic cherts * distribution Subject RIV: AC - Archeology, Anthropology, Ethnology

  19. Objev vápenců s rohovci v Boskovické brázdě

    Czech Academy of Sciences Publication Activity Database

    Krmíček, Lukáš; Bartík, J.; Bubík, M.

    2014-01-01

    Roč. 99, č. 2 (2014), s. 73-84 ISSN 1211-8796 Institutional support: RVO:67985831 Keywords : South Moravia * Boskovice Furrow * micritic-peloidal/oolitic limestone * dark chert * sabkha environment Subject RIV: DB - Geology ; Mineralogy

  20. Thermal Infrared Spectra of Microcrystalline Sedimentary Phases: Effects of Natural Surface Roughness on Spectral Feature Shape

    Science.gov (United States)

    Hardgrove, C.; Rogers, A. D.

    2012-03-01

    Thermal infrared spectral features of common microcrystalline phases (chert, alabaster, micrite) are presented. Spectra are sensitive to mineralogy and micron-scale (~1-25 µm) surface roughness. Roughness is on the scale of the average crystal size.

  1. Epigondolella abneptis and E. spatulata in the Lower Norian in the central Kamnik Alps, Slovenia

    Directory of Open Access Journals (Sweden)

    Anton Ramovš

    1994-12-01

    Full Text Available Epigondolella abneptis (Huckriede, 1958 and E. spatulata (Hayashi, 1968from the Lower Norian (Upper Triassic deeper marine micritic limestones with chert nodules and lenses in the locality Sleme, central Kamnik Alps, are presented.

  2. Report of Surface Collection and Testing at 18 Sites Near Abiquiu Reservoir, Northern New Mexico

    Science.gov (United States)

    1989-10-01

    the nineteenth century are described as canvas tents apparently held down by stones and pegs forming a circular structure; most cooking was done...02.) FOSSIL GRAY: Gray to tan chert. This code was used although the type does not represent the classic " fingerprint " chert. Permian. (Materials...signature of Cerro del Medio obsidian, and four artifacts (Cat. nos. 86-775, -836., -842, and -854) correspond with the fingerprint of Obsidian Ridge

  3. Preliminary view of geotechnical properties of soft rocks of Semanggol formation at Pokok Sena, Kedah

    Science.gov (United States)

    Ahmad, N. R.; Jamin, N. H.

    2018-04-01

    The research was inspired by series of geological studies on Semanggol formation found exposed at North Perak, South Kedah and North Kedah. The chert unit comprised interbedded chert-shale rocks are the main lithologies sampled in a small-scale outcrop of Pokok Sena area. Black shale materials were also observed associated with these sedimentary rocks. The well-known characteristics of shale that may swell when absorb water and leave shrinkage when dried make the formation weaker when load is applied on it. The presence of organic materials may worsen the condition apart from the other factors such as the history of geological processes and depositional environment. Thus, this research is important to find the preliminary relations of the geotechnical properties of soft rocks and the geological reasoning behind it. Series of basic soil tests and 1-D compression tests were carried out to obtain the soil parameters. The results obtained gave some preliminary insight to mechanical behaviour of these two samples. The black shale and weathered interbedded chert-shale were classified as sandy-clayey-SILT and clayey-silty-SAND respectively. The range of specific gravity of black shale and interbedded chert/shale 2.3 – 2.6 and fall in the common range of shale and chert specific gravity value. In terms of degree of plasticity, the interbedded chert/shale samples exhibit higher plastic degree compared to the black shale samples. Results from oedometer tests showed that black shale samples had higher overburden pressure (Pc) throughout its lifetime compare to weathered interbedded chert-shale, however the compression index (Cc) of black shale were 0.15 – 0.185 which was higher than that found in interbedded chert-shale. The geotechnical properties of these two samples were explained in correlation with their provenance and their history of geological processes involved which predominantly dictated the mechanical behaviour of these two samples.

  4. Revise of a basic data base for shielding design

    International Nuclear Information System (INIS)

    Nakao, Makoto; Takemura, Morio

    2000-03-01

    With use of the two-dimensional discrete ordinates code DORT and the standard groupwise shielding design library JSSTDL produced from the latest evaluated nuclear data library JENDL-3.2, experimental analyses for the representative configurations in the Radial Shield Attenuation Experiment of the JASPER were performed. The results were compared with those obtained with use of traditional method DOT3.5/JSDJ2 for the previous JASPER experimental analyses. In general, the change of the cross section library gives higher results and the change of the transport code gives lower results. Finally the new analysis method gives better agreement with the experimental results and also less deviations of calculational errors between various detectors. Experimental analyses for the thick concrete configuration in the Gap Streaming Experiment of the JASPER was also performed with the new analysis method, after solving the poor agreement found in last year with the original JASPER experimental analyses. The same tendency due to the library change was confirmed with the above mentioned analyses of the Radial Shield Attenuation Experiment. Compilation of the input data necessary for future reanalyses of important configurations in JASPER experiments were continued through the above-mentioned experimental analyses and related informations were added for repletion of the database preserved in a computer disk holding previously accumulated data. Input data descriptions were made for auxiliary routines needed for the experimental analyses and their sample data were compiled and stored in the database. (author)

  5. Self-Disturbance and the Bizarre: On Incomprehensibility in Schizophrenic Delusions.

    Science.gov (United States)

    Sass, Louis A; Byrom, Greg

    2015-01-01

    The notion of 'bizarre delusion' has come into question in contemporary anglophone psychopathology. In DSM-5, it no longer serves as a special criterion for diagnosing schizophrenia nor as an exclusion criterion for delusional disorder. Empirical studies influencing this development have, however, been relatively sparse and subject to methodological criticism. Major reviews have concluded that current conceptualizations of bizarre delusions may require rethinking and refinement. Defining bizarreness entails a return to Jaspers, whose influential views on the supposed incomprehensibility of bizarre delusions and schizophrenic experience are more nuanced than is generally recognized. Jaspers insisted we must 'get behind' three 'external characteristics' (extraordinary conviction, imperviousness, impossible content) in order to acknowledge a 'primary experience traceable to the illness' in the 'delusions proper' of schizophrenia. He also denied that one could empathize with or otherwise 'understand' this basis. Here, we focus on three features of bizarre delusions that Jaspers foregrounded as illustrating schizophrenic incomprehensibility: disturbance of the cogito, certitude combined with inconsequentiality, delusional mood. We link these with the contemporary ipseity disturbance model of schizophrenia, arguing that Jaspers' examples of incomprehensibility can be understood as manifestations of the three complementary aspects of ipseity-disturbance: diminished self-presence, hyperreflexivity and disturbed grip/hold. We follow Jaspers' lead in acknowledging a distinctive strangeness that defies ready comprehension, but we challenge the absolutism of Jaspers' skepticism by offering a phenomenological account that comprehends bizarreness in two ways: rendering it psychologically understandable, and fitting the various instances of bizarreness into a comprehensive explanatory framework. © 2015 S. Karger AG, Basel.

  6. Individual and population dose to users of the Savannah River following K-Reactor tritium release

    International Nuclear Information System (INIS)

    Carlton, W.H.; Hamby, D.M.

    1992-01-01

    Approximately 5700 curies of tritium were released to Pen Branch between December 22, 1991 and December 25, 1991. As expected, the tritiated water traveled through the Savannah River swamp to Steel Creek and the Savannah River. Elevated tritium concentrations in the river at Becks Ferry (Beaufort-Jasper) and Abercorn Creek (Port Wentworth) has caused some concern among downstream water users as to the amount of tritium available for uptake through the domestic drinking water supplies at the Beaufort-Jasper and Port Wentworth water treatment facilities. Radiation dose to the downstream drinking water population is estimated in this report

  7. Primary studies of trace quantities of green vegetation in Mono Lake area using 1990 AVIRIS data

    Science.gov (United States)

    Chen, Zhi-Kang; Elvidge, Chris D.; Groeneveld, David P.

    1992-01-01

    Our primary results in Jasper Ridge Biological Preserve indicate that high spectral resolution Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data may provide a substantial advantage in vegetation, based on the chlorophyll red edge feature from 700-780 nm. The chlorophyll red edge was detected for green vegetation cover as low as 4.8 percent. The objective of our studies in Mono Lake area is to continue the experiments performed in Jasper Ridge and to examine the persistence of red edge feature of trace quantities of green vegetation for different plant communities with non-uniform soil backgrounds.

  8. Stone tools from locality Crkvine in Stubline

    Directory of Open Access Journals (Sweden)

    Antonović Dragana

    2011-01-01

    Full Text Available Stone artifacts from excavations in Crkvine in 2008. originate from two stratigraphic units, both chronologically defined as the final stage of the Vinča culture: 1. distruction layer above and 2. from the floor of House 1/2008. None of the stone artifact types showed any specific regularity in vertical distribution. However, in the southern part of the Structure/House 1 there is higher abundance in horizontal distribution of both types of tools. Abundance of cores, blades for rejuvenation of the cores and unretouched blades among the chipped artifacts suggest that, most probably, this object was a working place where the artifacts were made (Fig. 9/1. Ground stone artifacts - all rought-out and final products, whole and fragmented pieces, ground-edge and abrasive tools, are equally distributed in the House 1/2008 as well as in the distruction layer above it. Only non-determined fragments and pieces of raw material, both defined as products of making stone tools, are far more numerous in the distruction layer above the House 1/2008. Higher concentrations of finds are situated in the House 1/2008, especially in its southern part, on the floor and above it, while the number of finds out of the House significantly decreases (Fig. 9/2. Such distribution of ground stone artifacts indicates that the production of stone artifacts was done within the household (large number of flakes of „light white stone“, presence of grindstone and whetstone, as well as that there occurred active preparation of food within the Vinča’s objects (querns and pounders within the houses. Findings of numerous quartzite, chert and jasper pebbles out of the House 1/2008, 2 metres away from the northeastern angle of the House (pottery group 1, could not be connected with production of chipped and ground stone artifacts. There are no any traces of treatment and utilization on the pebbles, and the pebbles themselves do not belong to raw material of good quality due to

  9. Templates, Numbers & Watercolors.

    Science.gov (United States)

    Clemesha, David J.

    1990-01-01

    Describes how a second-grade class used large templates to draw and paint five-digit numbers. The lesson integrated artistic knowledge and vocabulary with their mathematics lesson in place value. Students learned how draftspeople use templates, and they studied number paintings by Charles Demuth and Jasper Johns. (KM)

  10. 75 FR 20035 - Petition for Waiver of Compliance

    Science.gov (United States)

    2010-04-16

    ...'s arguments in favor of relief. City of Jasper, Indiana [Docket Number FRA-2009-0112] The City of.... The car is currently equipped with automotive-type laminated glazing, which is non-compliant with FRA... waiver request is the high cost of compliant FRA Types I & II glazing material, and that the automotive...

  11. Nigerian Journal of General Practice: Contact

    African Journals Online (AJOL)

    Principal Contact. Dr Jasper Jideofor Onyekwelu Editor-in-Chief Christ Hospital. Obinwanne Hospital and Maternity,. 19 Uba Street, Nkpor. Anambra State, Nigeria. Phone: +2348033430651. Email: drjideonyekwelu@yahoo.com. Support Contact. Dr Ernest O. Eze-Okoye Phone: +234-803-241-4323

  12. Dealing with Human Death: The Floating Perspective.

    Science.gov (United States)

    Kenyon, Gary M.

    1991-01-01

    Explores approach to dealing with human death. Describes floating perspective, based on insights from Choron and Jaspers, as suggesting it is possible to deal with human death by refraining from taking ultimate position on the problem. Position encourages openness to death. Examines role of anxiety and describes possible meaningful outcomes of…

  13. Tulge vaatama filme eesti kunstnikest!

    Index Scriptorium Estoniae

    2002-01-01

    24. V Tallinna Kunstihoones filmiprogramm: Peeter Brambat "Müütide mäss", 2002 (Lembit Sarapuust); Rühm+0 (režissöör Meelis Salujärv) "Erki Kasemets", 2002; Mari Sobolev ja Jasper Zoova "The Kids of Rock'n roll", 2000; Tiina Kolgi portreesaade "Õnne sünnipäevaks, Tiina Tammetalu"

  14. Jaapani meditatsiooni, erootikat ja vägivalda / Margit Adorf

    Index Scriptorium Estoniae

    Adorf, Margit, 1974-

    2011-01-01

    Tallinna Kinomajas 25.-28. aug.-ni toimuvast Aasia sõltumatute filmide festivalist EVA - East via Asia. Festivali korraldaja Helen Merila. Festival sündis koostöös Zipangu Fest Japananarchy in UK peakorraldaja Jasper Sharpiga

  15. Restoran-apteek Londonis

    Index Scriptorium Estoniae

    1999-01-01

    Damien Hirsti kujundatud restoran Pharmacy Londonis, trendiinimeste lemmikkohti. Kahekorruselist maja täitev söögikoht on täis meditsiinilisi vihjeid. Haiglameeleolu hajutavad interjööris ja mööblikujunduses (mööbel Jasper Morrison) kasutatud soojad materjalid.

  16. Gemstones

    Science.gov (United States)

    Olson, D.W.

    2013-01-01

    The estimated value of natural gemstones produced from U.S. deposits during 2012 was $11.1 million, a slight increase from 2011. U.S. gemstone production included agate, amber, beryl, coral, garnet, jade, jasper, opal, pearl, quartz, sapphire, shell, topaz, tourmaline, turquoise and many other gem materials.

  17. Ways of Dying

    DEFF Research Database (Denmark)

    Michaelsen, Cathrine Bjørnholt

    2014-01-01

    , respectively. “Numquam enim erit homini peius in morte, quam ubi erit mors ipsa sine morte.”¹ “Wiederholung ist nur in Gestalt der Treue nicht Endlosigkeit, sondern Erfüllung.”² 1. St. Augustine, De Civitate Dei, XIII, 11. 2. Karl Jaspers, Philosophie. II. Existenzerhellung, Berlin, Heidelberg and New York...

  18. Proceedings of the National Workshop on Containment Area Aquaculture Held in South Padre Island, Texas on 11-15 November 1991

    Science.gov (United States)

    1993-12-01

    animals unfit with fish meal supply resulting from El Nihio for human consumption. Thus, care must be events off Peru and Chile in the past have led taken...commercial feasibility Sorgeloos, 0. Roels, and E. Jaspers, ed., of prawn (Macrobrachium rosenbergii) The brine shrimp Anemia , Universal farming in

  19. Postfire environmental conditions influence the spatial pattern of regeneration for Pinus ponderosa

    Science.gov (United States)

    V. H. Bonnet; Anna Schoettle; W. D. Shepperd

    2005-01-01

    Regeneration of ponderosa pine after fire depends on the patterns of seed availability and the environmental conditions that define safe sites for seedling establishment. A transect approach was applied in 2002 to determine the spatial distribution of regeneration from unburned to burned areas within the landscape impacted by the Jasper Fire of 2000 in the...

  20. Nooremas keskeas klassikute nukuteater / Sandra Jõgeva

    Index Scriptorium Estoniae

    Jõgeva, Sandra, 1976-

    2010-01-01

    Silja Saarepuu ja Villu Plingi näitus "Aknal" Pärnu Kunstihallis 28. veebruarini 2010. Suure osa eksponeeritud loomingust hõlmab nn väikeste inimeste teema. Jasper Zoova ruumiliste maalide näitus "Jass tuli koju" Jazz Cafés Pärnus 3. märtsini 2010

  1. Arhitektuuriuudised / Karen Jagodin

    Index Scriptorium Estoniae

    Jagodin, Karen, 1982-

    2007-01-01

    Trossidega majale kinnitatud rippuv tuba (autor Stefan Eberstadt); disainikooli hoone Saksamaa tööstuspiirkonnas (arhitektid Kazuyo Sejima ja Ryue Nishizawa); hiidlille kujuline elamu Hollandis (arhitektid Ben Huygen ja Jasper Jägers); Fuji mäe kujuline eramu Jaapanis (arhitekt Yuko Nagayama); AR Arhitektuuriauhinnad noorele arhitektile; laeva ja püramiidi hübriidi vormiga elamu (arhitekt Katsuhiro Miyamoto)

  2. Eesti naksitrallid Poolas / Flavek Kowalsky

    Index Scriptorium Estoniae

    Kowalsky, Flavek

    2000-01-01

    8. märtsist Sopoti galeriis "Marzenie Provincionalnej Dziewczyny" ("Provintsitüdruku Unistus") samanimelise näitusesarja näitus "Provintsipoisi unistus". Kuraator Paulina M. Olowska. Eestlaste Jasper Zoova, Tarrvi Laamannni ja Kiwa töödest. Kunstiväljapanekule sekundeerinud muusikaõhtul klubis "Sfinks" esinesid T. Laamannn ja Kiwa pop-projektiga "Nervous cowboys".

  3. Parallelnõi mir hudozhnika / Ljudmila Pribõlskaja

    Index Scriptorium Estoniae

    Pribõlskaja, Ljudmila

    2007-01-01

    Jasper Zoova näitus "Suurlinna tuled" Pärnu Muuseumi näitusesaalis. Näha on õlimaalid ja plakatisari "PARALLEL EU". Tööd üldnimetusega "PARALLEL EU" on konkursitöö graafikatriennaali näitusele ѕPoliitiline/poeetilineأ, mis toimub sügisel Kumus. Kunstniku kommentaarid

  4. Oodatav tsensuuri moment on osa kunstilisest teostusest / Tiiu Leis

    Index Scriptorium Estoniae

    Leis, Tiiu

    1998-01-01

    Viljandis toimunud kunstipäevade "Kiriküüt" raames Pärnu-Ikla-Tartu-Tallinna maanteel valminud "Maantee näituse", kus pärnakaist esinevad Andrus Joonas, Sütevaka Andres, Taave Tuutmaa, Kadri Alesmaa, filmile (teost. Jasper Zoova) jäädvustamiseks korraldatud bussireisist ja intsidendist graffiti'ga kaetud bussi pärast.

  5. Matti Nykänen : olen elust õppust võtnud / Matti Nykänen ; intervjueerinud Urmo Soonvald

    Index Scriptorium Estoniae

    Nykänen, Matti, 1963-

    2006-01-01

    Vestlus Soome endise suusahüppajaga. Ka eluloofilmist "Matti - põrgu kuulub kangelastele" (režissöör Aleksi Mäkelä, nimiosas Jasper Pääkkönen). Lisatud tema saavutuste ja kirevate eluseikade kronoloogia

  6. Matti Nykänen hüppab Eestis ekraanile

    Index Scriptorium Estoniae

    2006-01-01

    Režissöör Aleksi Mäkelä film suusahüppaja Matti Nykäneni elust "Matti - põrgu kuulub kangelastele", nimoiosas Jasper Pääkkönen. Tänasest ka Tallinnas ekraanil, Soomes on filmil rekordarv vaatajaid

  7. Kohtumispaik Szczecin

    Index Scriptorium Estoniae

    1999-01-01

    Läänemeremaade kunstnike näitus 'N.E.W.S.' 29. X-5. XII Poolas Szczecini lossis. Eesti väljapaneku konsultant Heie Treier, Eestist osalevad Inessa Josing, Mart Viljus, Jasper Zoova, Mari Laanemets, Killu Sukmit. Üldkuraatorid loetletud

  8. Eestlased hõivasid Lissaboni / Rael Artel

    Index Scriptorium Estoniae

    Artel, Rael, 1980-

    2001-01-01

    18. maist Rael Arteli kureeritud eesti kunsti näitus "Nyyd Estonian Malady" Zé dos Boisi galeriis. Osalevad Silja Saarepuu, Kiwa, Mari Laanemets, Killu Sukmit, Kadi Estland. Näidatakse Marko Raadi, Mari Sobolevi ja Jasper Zoova videofilme. R. Arteli ja M. Laanemetsa videoloengud eesti ja ida-euroopa noorest sotsiaalsest kunstist.

  9. 77 FR 15450 - Tier 1 Environmental Impact Statement for the Chicago, Illinois, to Omaha, Nebraska, Regional...

    Science.gov (United States)

    2012-03-15

    ... Island counties, Illinois; Scott, Muscatine, Cedar, Johnson, Iowa, Poweshiek, Jasper, Polk, Dallas...'' (Transportation Economics & Management Systems, Inc., September 2004). Alternatives to be Considered: The Tier 1... and the Iowa DOT 10 Year Strategic Passenger-Rail Plan. The previously established primary passenger...

  10. Kõik on kunst, kunst on kõikjal / Tiiu Leis

    Index Scriptorium Estoniae

    Leis, Tiiu

    1998-01-01

    25. juulil toimus Pärnus raehoovis kehamaalimise üritus, mille kuraatoriks Ene-Liis Semper, kunstnikud Marko Laimre, Kiwa, Jasper Zoova, Tarrvi Laamann ning mis toimus Barclay sigarettide reklaamikampaania 'Art is Everywhwere' (eestipoolne korraldaja Per Li ehk Pear Väli) raames.

  11. Novosti modõ / Jevgenija Fedorovskaja

    Index Scriptorium Estoniae

    Fedorovskaja, Jevgenija

    2001-01-01

    Kõrgmoenädalast Londonis - muudatusi seoses terroriaktiga New Yorgis. Jasper Conrani, Oscar de la Renta, Markus Lüpferi, John Rocha, Londoni kunstnike-dueti Blaak (pärit Lõuna-Aafrikast) kollektsioonidest ja poola kunstniku Arkadiuse art-objektide esitlusest

  12. Randomized comparative efficacy study of parent-mediated interventions for toddlers with autism.

    Science.gov (United States)

    Kasari, Connie; Gulsrud, Amanda; Paparella, Tanya; Hellemann, Gerhard; Berry, Kathleen

    2015-06-01

    This study compared effects of two parent-mediated interventions on joint engagement outcomes as augmentations of an early intervention program for toddlers with autism spectrum disorder (ASD). Participants included 86 toddlers (range 22-36 months) with ASD and their primary caregiver. Caregiver-child dyads were randomized to receive 10 weeks of hands-on parent training in a naturalistic, developmental behavioral intervention (joint attention, symbolic play, engagement and regulation-JASPER) or a parent-only psychoeducational intervention (PEI). Dose was controlled in terms of researcher-parent contact and early intervention services received by the child. Results yielded significant effects of the JASPER intervention on the primary outcome of joint engagement. The treatment effect was large (Cohen's f² = .69) and maintained over the 6-month follow-up. JASPER effects were also found on secondary outcomes of play diversity, highest play level achieved, and generalization to the child's classroom for child-initiated joint engagement. The PEI intervention was found to be effective in reducing parenting stress associated with child characteristics. All secondary effects were generally small to moderate. These data highlight the benefit of a brief, targeted, parent-mediated intervention on child outcomes. Future studies may consider the combination of JASPER and PEI treatments for optimal parent and child outcomes. Trial registry no. NCT00999778. (c) 2015 APA, all rights reserved).

  13. Kolm raamistikku Mäetamme unenäole / Katrin Kivimaa

    Index Scriptorium Estoniae

    Kivimaa, Katrin, 1969-

    2008-01-01

    Kunstniku unenäo materialiseerimisest ja aktualiseerimisest. Marko Mäetamme tekstilisest videoteosest "Pealkirjata" (2007), mis olevat ilmunud kunstnikule unenäos. Inglise kunstiajaloolane Fred Orton ameerika kunstniku Jasper Johnsi tööst "Lipp". S. Freudi teosest "Unenägude tõlgendamine"

  14. Young British Art / Hanno Soans

    Index Scriptorium Estoniae

    Soans, Hanno, 1974-

    2001-01-01

    1990ndate kunsti muutumisest. Inglise kunstniku Peter Daviese maalist "Kuum esimene sada" (1996), Gavin Turki vahakujuna valminud autoportreest "Pop". "Young British Art'i" uuskunstist ja Jasper Zoova installatsioonist "F1". Eri analüüsivõimalusi pakkuvatest töödest (Marko Laimre & Ene-Liis Semperi 2000. a. novembri ühisnäituse osa töid).

  15. The physician in the technological age.

    Science.gov (United States)

    Jaspers, K

    1989-09-01

    Translator's summary and notes: Karl Jaspers (1883-1969) argues that modern advances in the natural sciences and in technology have exerted transforming influence on the art of clinical medicine and on its ancient Hippocratic ideal, even though Plato's classical argument about slave physicians and free physicians retains essential relevance for the physician of today. Medicine should be rooted not only in science and technology, but in the humanity of the physician as well. Jaspers thus shows how, within the mind of every medical person, the researcher contests with the physician and the technician with the humanist. Jaspers therefore opposes all modern tendencies that regard men as abstractions. As a creative existentialist influenced by Kierkegaard, Nietzsche, and Husserl, he reasons that clinical medicine should always treat patients as irreducable individuals, and his thinking on psychotherapy argues for a realm of interiority, freedom, intelligibility, and existential communication that transcends the reach of the causal thinking of natural science. This essay, written in 1959, reflects Jaspers' lifelong preoccupation with the philosophical meaning of medicine (he received his MD degree in 1909) and the totality of the human person. It should significantly enhance our own comprehension of medical power, dangers, reasoning, and accomplishments.

  16. Nervous Cowboys ja Eesti kui märk Prahas

    Index Scriptorium Estoniae

    1999-01-01

    16. XI toimus Tšehhi pealinna Praha Karli sillal Eesti Taassünnipäevale pühendatud performance 'Eesti kui märk', mille viis läbi kunstirühmitus Nervous Cowboys koosseisus Kiwa ja Jasper Zoova. Eesti Suursaatkonnas avati näitus, kus eksponeeritakse xerox-tehnikas graafilisi lehti ja performance'i videdokumentatsiooni.

  17. Fideo ja Vilm Pärnus

    Index Scriptorium Estoniae

    1999-01-01

    Pärnu Fideo- ja Vilmifestival 2.-3. apr. Muuseumi Aidas. Margus Tiitsmaa ja Sütevaka Andrese performance'test. Jasper Zoova ja Erno Võsa installatsioonist "Eesti mehe ja naise identifitseerimise masin". Taivani kunstniku Eliza Lin'i fotoinstallatsioonist ja videost

  18. Early Behavioral Intervention to Improve Social Communication Function in Infants with TSC

    Science.gov (United States)

    2016-10-01

    Disability (ID) using the...infant to complete the JASPER intervention at the UCLA site, acquired during our Social Scenes Paradigm (see Figures 1 & 2). The plot demonstrates that...Theory in Intellectual and Developmental Disabilities San Diego, CA • Jeste, S.S., (2016). Can rare disorders pave the way to

  19. 40 CFR 81.311 - Georgia.

    Science.gov (United States)

    2010-07-01

    ... County X Hart County X Heard County X Henry County X Houston County X Irwin County X Jackson County X Jasper County X Jeff Davis County X Jefferson County X Jenkins County X Johnson County X Jones County X... County X Hart County X Heard County X Henry County X Houston County X Irwin County X Jackson County X...

  20. 77 FR 72886 - Amendment of Statement of Organization and Functions; Restructuring of National Labor Relations...

    Science.gov (United States)

    2012-12-06

    ..., Cumberland, Davidson, DeKalb, Dickson, Fentress, Franklin, Giles, Grundy, Henry, Hickman, Houston, Humphreys..., Hall, Hancock, Haralson, Harris, Hart, Heard, Henry, Houston, Irwin, Jackson, Jasper, Jefferson, Jenkins, Johnson, Jones, Lamar, Laurens, Lee, Liberty, Lincoln, Long, Lumpkin, McDuffie, McIntosh, Macon...

  1. The Sartre-Heidegger Controversy on Humanism and the Concept of Man in Education

    Science.gov (United States)

    Kakkori, Leena; Huttunen, Rauno

    2012-01-01

    Jean-Paul Sartre claims in his 1945 lecture "Existentialism is a Humanism" that there are two kinds of existentialism: that of Christians like Karl Jaspers, and atheistic like Martin Heidegger. Sartre's "spiritual master" Heidegger had no problem with Sartre defining him as an atheist, but he had serious problems with Sartre's…

  2. Eesti noorkunstnikud unistavad Poolas

    Index Scriptorium Estoniae

    2000-01-01

    8. märtsist Sopoti galeriis Marzenie Provincionalnej Dziewczyny (Provintsitüdruku unistus) samanimelise näitusesarja näitus 'Provintsipoisi unistus'. Kuraator Paulina M. Olowska. Eestist osalesid Jasper Zoova, Tarrvi Laamannn, Kiwa. Poola kunstiteadlane Flavek Kowalsky eestlaste töödest.

  3. 77 FR 26045 - Notice Pursuant to the National Cooperative Research and Production Act of 1993-Accellera Systems...

    Science.gov (United States)

    2012-05-02

    ..., IRELAND; Freescale Semiconductor, Austin, TX; IBM, Hopewell Junction, NY; Jasper Design Automation..., San Jose, CA; Vayavya Labs, Belguam, INDIA; Verilab, Austin, TX; and Xilinx, Inc., San Jose, CA, have.... The Department of Justice published a notice in the Federal Register pursuant to Section 6(b) of the...

  4. Development of a mixed seawater-hydrothermal fluid geochemical signature during alteration of volcanic rocks in the Archean (∼2.7 Ga) Abitibi Greenstone Belt, Canada

    Science.gov (United States)

    Brengman, Latisha A.; Fedo, Christopher M.

    2018-04-01

    We investigated a group of silicified volcanic rocks from the ∼2.72 Ga Hunter Mine Group (HMG), Abitibi Greenstone Belt, Canada, in order to document progressive compositional change associated with alteration in a subaqueous caldera system. Rocks of the HMG divide into three groups based on mineralogy and texture for petrographic and geochemical analyses. Volcanic features (phenocrysts, pseudomorphs after primary glass shards, lapilli, volcanic clasts) are preserved in all groups, despite changing mineralogy from primarily quartz, feldspar, chlorite (Groups 1 and 2), to quartz, hematite and carbonate (Groups 2 and 3). Compositionally, Group 1 rocks resemble volcanic rocks in the region, while Group 2 and 3 rocks show a change in mineralogy to iron, silica, and carbonate minerals, which is associated with depletion of many major and trace elements associated with volcanic rocks (Al2O3, Na2O, K2O, Zr). In addition, rare earth elements display a clear progression from volcanic signatures in Group 1 (PrSN/YbSN = 1.7-2.96, EuSN/EuSN∗ = 0.84-1.72, Y/Ho = 25.20-27.41, LaSN/LaSN∗ = 0.97-1.29, and Zr/Hf = 38.38-42.09) to transitional mixed volcanic, hydrothermal, and seawater signatures in Group 2 (PrSN/YbSN 1.33-2.89, EuSN/EuSN∗ 1.33-2.5, Y/Ho = 23.94-30, LaSN/LaSN∗ 0.93-1.34, and Zr/Hf = 40-70), to mixed hydrothermal and seawater signatures in Group 3 (PrSN/YbSN 0.62-2.88, EuSN/EuSN∗ 1.30-7.15, LaSN/LaSN∗ 1.02-1.86, Y/Ho = 25.56-55, and Zr/Hf = 35-50). We interpret that silicification of volcanic rocks (Group 1) produced transitional altered volcanic rocks (Group 2), and siliceous and jaspilitic rocks (Group 3), based on preservation of delicate volcanic features. Building on this explanation, we interpret that major, trace- and rare-earth element mobility occurred during the process of silicification, during which siliceous and jaspilitic rocks (Group 3) acquired aspects of the rare-earth element geochemical signatures of marine chemical precipitates. We

  5. Palaeoenvironmental and geochemical approach of Archaeocyath-rich facies from Lower Cambrian of Western Gondwana margin at Central Iberian Zone (Urda, Toledo Mountains, Spain)

    Science.gov (United States)

    Menéndez, Silvia; Rodríguez-Martínez, Marta; Moreno-Eris, Elena; Perejón, Antonio; Reitner, Joachim

    2010-05-01

    Archaeocyath-rich facies are located in a quarry close to Urda village, at Toledo Mountains, Spain. The outcrops belong to the Caliza de los Navalucillos Formation and they record a considerably high diverse archaeocyath assemblage in the Lower Cambrian successions from the Central Iberian Zone (Julivert et al. 1972 [1974]). In fact, it is first time recorded the presence of Agyrekocyathus, Dokidocyathus, and Plicocyathus in the Central Iberian Zone. Therefore Plicocyathus is no longer exclusive to biozone VI in Spain. The presence of Anthomorpha is characteristic for the early Botomian, presently early Stage 4 (ICS, 2009), and the assemblage corresponds to the biozone VII (late Ovetian, following the biozonation of Perejón & Moreno-Eiris, 2006). The fossiliferous part of the succession is formed by seven lithofacies, all of them tectonically folded and with a low grade metamorphic overprint. They are comprised by two main groups of facies: (a) mound-shaped to massive lithofacies (A1, A2, A3, A4) and (b) massive to bedded and nodular lithofacies (B1, B2, B3). Archaeocyaths occur in several facies: (A1) mound-shaped white marble with irregular to stromatactoid cavities; (A2) massive mottled white to grey limestone; (A3) massive grey limestone with slumps levels; (A4) massive archaeocyath-rich orange limestone; as well as in carbonate nodules embedded in siltstones and cherts (B1, B2 and B3). The best preserved assemblage comes from the nodule record, where fossils are partially pyritized. This type of preservation is exceptional and has never been described before. XRD and wavelength-dispersive electron microprobe analyses reveal the presence of pyrite and pyrrotine partially altered to iron oxides and hydroxides (hematite and goethite) surrounding the archaeocyath cups. In Central Iberian Zone, the development of mounds and nodular facies like those described here is unusual, although the Botomian marks the peak for Early Cambrian archaeocyathan-microbial mounds

  6. Stratigraphy of the PB-1 well, Nopal I uranium deposit, Sierra Pena Blanca, Chihuahua, Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Dobson, P.; Fayek, M.; Goodell, P.; Ghezzehei, T.; Melchor, F.; Murrell, M.; Oliver, R.; Reyes-Cortes, I.A.; de la Garza, R.; Simmons, A.

    2008-08-01

    The Nopal I site in the Pena Blanca uranium district has a number of geologic and hydrologic similarities to the proposed high-level radioactive waste repository at Yucca Mountain, making it a useful analogue to evaluate process models for radionuclide transport. The PB-1 well was drilled in 2003 at the Nopal I uranium deposit as part of a DOE-sponsored natural analogue study to constrain processes affecting radionuclide transport. The well penetrates through the Tertiary volcanic section down to Cretaceous limestone and intersects the regional aquifer system. The well, drilled along the margin of the Nopal I ore body, was continuously cored to a depth of 250 m, thus providing an opportunity to document the local stratigraphy. Detailed observations of these units were afforded through petrographic description and rock-property measurements of the core, together with geophysical logs of the well. The uppermost unit encountered in the PB-1 well is the Nopal Formation, a densely welded, crystal-rich, rhyolitic ash-flow tuff. This cored section is highly altered and devitrified, with kaolinite, quartz, chlorite, and montmorillonite replacing feldspars and much of the groundmass. Breccia zones within the tuff contain fracture fillings of hematite, limonite, goethite, jarosite, and opal. A zone of intense clay alteration encountered in the depth interval 17.45-22.30 m was interpreted to represent the basal vitrophyre of this unit. Underlying the Nopal Formation is the Coloradas Formation, which consists of a welded lithic-rich rhyolitic ash-flow tuff. The cored section of this unit has undergone devitrification and oxidation, and has a similar alteration mineralogy to that observed in the Nopal tuff. A sharp contact between the Coloradas tuff and the underlying Pozos Formation was observed at a depth of 136.38 m. The Pozos Formation consists of poorly sorted conglomerate containing clasts of subangular to subrounded fragments of volcanic rocks, limestone, and chert

  7. Stratigraphy of the PB-1 well, Nopal I uranium deposit, Sierra Pena Blanca, Chihuahua, Mexico

    International Nuclear Information System (INIS)

    Dobson, P.; Fayek, M.; Goodell, P.; Ghezzehei, T.; Melchor, F.; Murrell, M.; Oliver, R.; Reyes-Cortes, I.A.; de la Garza, R.; Simmons, A.

    2008-01-01

    The Nopal I site in the Pena Blanca uranium district has a number of geologic and hydrologic similarities to the proposed high-level radioactive waste repository at Yucca Mountain, making it a useful analogue to evaluate process models for radionuclide transport. The PB-1 well was drilled in 2003 at the Nopal I uranium deposit as part of a DOE-sponsored natural analogue study to constrain processes affecting radionuclide transport. The well penetrates through the Tertiary volcanic section down to Cretaceous limestone and intersects the regional aquifer system. The well, drilled along the margin of the Nopal I ore body, was continuously cored to a depth of 250 m, thus providing an opportunity to document the local stratigraphy. Detailed observations of these units were afforded through petrographic description and rock-property measurements of the core, together with geophysical logs of the well. The uppermost unit encountered in the PB-1 well is the Nopal Formation, a densely welded, crystal-rich, rhyolitic ash-flow tuff. This cored section is highly altered and devitrified, with kaolinite, quartz, chlorite, and montmorillonite replacing feldspars and much of the groundmass. Breccia zones within the tuff contain fracture fillings of hematite, limonite, goethite, jarosite, and opal. A zone of intense clay alteration encountered in the depth interval 17.45-22.30 m was interpreted to represent the basal vitrophyre of this unit. Underlying the Nopal Formation is the Coloradas Formation, which consists of a welded lithic-rich rhyolitic ash-flow tuff. The cored section of this unit has undergone devitrification and oxidation, and has a similar alteration mineralogy to that observed in the Nopal tuff. A sharp contact between the Coloradas tuff and the underlying Pozos Formation was observed at a depth of 136.38 m. The Pozos Formation consists of poorly sorted conglomerate containing clasts of subangular to subrounded fragments of volcanic rocks, limestone, and chert

  8. Reply to the comment on the paper "Grain size dependent potential for self generation of magnetic anomalies on Mars via thermoremanent magnetic acquisition and magnetic interaction of hematite and magnetite" by Gunther Kletetschka, Norman F. Ness, J.E.P. Connerney, M.H. Acuna, P.J. Wasilewski, Phys. Earth Planet. Inter. 148 (2005) 149-156, made by: Jafar Arkani-Hamed

    Czech Academy of Sciences Publication Activity Database

    Kletetschka, Günther; Connerney, J. E. P.; Acuna, M. H.; Wasilewski, P. J.; Ness, F. N.

    2005-01-01

    Roč. 153, č. 4 (2005), s. 238-239 ISSN 0031-9201 Institutional research plan: CEZ:AV0Z30130516 Keywords : magnetic mineralogy * self-magnetization * Martian crust Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.420, year: 2005

  9. Geochemistry and Nd-isotope systematics of chemical and terrigenous sediments from the Dun Mountain Ophiolite, New Zealand

    International Nuclear Information System (INIS)

    Sivell, W.J.

    2002-01-01

    Two sedimentary associations closely related to temporally discrete ophiolitic magma suites occur within the Early Permian Dun Mountain Ophiolite Belt (DMOB), New Zealand. These are: (1) a suite of diverse chemical sediments and turbidite argillites (TA) that bear an intimate depositional relationship to early-formed pillow lavas (back-arc basin basalts); and (2) a younger, lithic-dominated, bimodal, coarse sandstone-ophiolitic rudite assemblage of proximal turbidite/mass-flow origin, rich in clasts of infant-arc magmas which comprise the bulk of the ophiolite. There are four groups of DMOB chemical sediments. Red hematitic chert (group 1) fills interstices between basalt pillows, and black nodular Fe-Mn deposits (group 2) occur along pillow lava/sediment interfaces. These facies are overlain by red mudstones (group 3), and mottled orange-olive brown mudstones (altered hyaloclastites; group 4). Geochemical features (including REE contents, Fe/Ti and transition ratios) indicate that the cherts reflect silica and metalliferous contributions to sea water, promoted by low-temperature hydrothermal alteration of glassy basalt, while group 4 muds represent residual components in halmyrolytically altered volcanic glass. Transition metal and REE enrichments in group 2 nodules (with high Ce/Ce*, Ni/Fe, and Cu/Fe ratios) reflect hydrogenous chemisorption to a hydothermal component (with high Ba and Sr). The nodules possess ε Nd (T) values (c. 0) identical to those calculated for Permian sea water. Group 3 red muds have lower ε Nd (T) = -1 to -2, and Nd model ages (T) Nd DM) that indicate contributions from continentally derived fluvial particulate fallout of mean Proterozoic age. For the nodules and red muds, strong negative correlations between Mn/Fe, Nd, Ce*/Ce, and ε Nd (T) are attributed to increasing diagenetic influence in the muds. ε Nd (T) values (c. +2) in group 4 muds are transitional toward higher values in their (hyaloclastite) basalt glass precursors

  10. Ideas and perspectives: hydrothermally driven redistribution and sequestration of early Archaean biomass - the "hydrothermal pump hypothesis"

    Science.gov (United States)

    Duda, Jan-Peter; Thiel, Volker; Bauersachs, Thorsten; Mißbach, Helge; Reinhardt, Manuel; Schäfer, Nadine; Van Kranendonk, Martin J.; Reitner, Joachim

    2018-03-01

    Archaean hydrothermal chert veins commonly contain abundant organic carbon of uncertain origin (abiotic vs. biotic). In this study, we analysed kerogen contained in a hydrothermal chert vein from the ca. 3.5 Ga Dresser Formation (Pilbara Craton, Western Australia). Catalytic hydropyrolysis (HyPy) of this kerogen yielded n-alkanes up to n-C22, with a sharp decrease in abundance beyond n-C18. This distribution ( ≤ n-C18) is very similar to that observed in HyPy products of recent bacterial biomass, which was used as reference material, whereas it differs markedly from the unimodal distribution of abiotic compounds experimentally formed via Fischer-Tropsch-type synthesis. We therefore propose that the organic matter in the Archaean chert veins has a primarily microbial origin. The microbially derived organic matter accumulated in anoxic aquatic (surface and/or subsurface) environments and was then assimilated, redistributed and sequestered by the hydrothermal fluids (hydrothermal pump hypothesis).

  11. 76 FR 60557 - Environmental Assessment and Finding of No Significant Impact for a License Amendment to...

    Science.gov (United States)

    2011-09-29

    ...: 301-415-5369; e-mail: [email protected] . SUPPLEMENTARY INFORMATION: I. Introduction The U.S. Nuclear... text and image files of the NRC's public documents. The ADAMS accession numbers for the documents... Analysis of Hydrogeologic ML093430807. Conditions in Overburden at Westinghouse Hematite Facility, Hematite...

  12. Preparation and crystallization of hollow α-Fe2O3 microspheres following the gas-bubble template method

    International Nuclear Information System (INIS)

    Valladares, L. de los Santos; León Félix, L.; Espinoza Suarez, S.M.; Bustamante Dominguez, A.G.; Mitrelias, T.; Holmes, S.; Moreno, N.O.; Albino Aguiar, J.; Barnes, C.H.W.

    2016-01-01

    In this work we report the formation of hollow α-Fe 2 O 3 (hematite) microspheres by the gas-bubble template method. This technique is simple and it does not require hard templates, surfactants, special conditions of atmosphere or complex steps. After reacting Fe(NO 3 ) 3 .9H 2 O and citric acid in water by sol–gel, the precursor was annealed in air at different temperatures between 180 and 600 °C. Annealing at 550 and 600 °C generates bubbles on the melt which crystallize and oxidizes to form hematite hollow spheres after quenching. The morphology and crystal evolution are studied by means of X-ray diffraction and scanning electron microscopy. We found that after annealing at 250–400 °C, the sample consist of a mixture of magnetite, maghemite and hematite. Single hematite phase in the form of hollow microspheres is obtained after annealing at 550 and 600 °C. The crystallization and crystal size of the hematite shells increase with annealing temperature. A possible mechanism for hollow sphere formation is presented. - Highlights: • Formation of hollow hematite microspheres by the gas-bubble template method. • This technique does not require hard templates or special conditions of atmosphere. • Annealing promotes the transition magnetite to maghemite to hematite. • Crystallization of the hematite shells increase with annealing temperature.

  13. Preparation and crystallization of hollow α-Fe{sub 2}O{sub 3} microspheres following the gas-bubble template method

    Energy Technology Data Exchange (ETDEWEB)

    Valladares, L. de los Santos, E-mail: ld301@cam.ac.uk [Cavendish Laboratory, Department of Physics, University of Cambridge, J.J Thomson Av., Cambridge, CB3 0HE (United Kingdom); León Félix, L. [Laboratorio de Cerámicos y Nanomateriales, Facultad de Ciencias Físicas, Universidad Nacional Mayor de San Marcos, Ap. Postal 14-0149, Lima (Peru); Laboratory of Magnetic Characterization, Instituto de Física, Universidade de Brasília, DF 70910-900, Brasilia (Brazil); Espinoza Suarez, S.M.; Bustamante Dominguez, A.G. [Laboratorio de Cerámicos y Nanomateriales, Facultad de Ciencias Físicas, Universidad Nacional Mayor de San Marcos, Ap. Postal 14-0149, Lima (Peru); Mitrelias, T.; Holmes, S. [Cavendish Laboratory, Department of Physics, University of Cambridge, J.J Thomson Av., Cambridge, CB3 0HE (United Kingdom); Moreno, N.O. [Departamento de Física, Universidade Federal de Sergipe, 49100-000, Sao Cristóvao, Sergipe (Brazil); Albino Aguiar, J. [Laboratório de Supercondutividade e Materiais Avançados, Departamento de Física, Universidade Federal de Pernambuco, 50670-901, Recife (Brazil); Barnes, C.H.W. [Cavendish Laboratory, Department of Physics, University of Cambridge, J.J Thomson Av., Cambridge, CB3 0HE (United Kingdom)

    2016-02-01

    In this work we report the formation of hollow α-Fe{sub 2}O{sub 3} (hematite) microspheres by the gas-bubble template method. This technique is simple and it does not require hard templates, surfactants, special conditions of atmosphere or complex steps. After reacting Fe(NO{sub 3}){sub 3}.9H{sub 2}O and citric acid in water by sol–gel, the precursor was annealed in air at different temperatures between 180 and 600 °C. Annealing at 550 and 600 °C generates bubbles on the melt which crystallize and oxidizes to form hematite hollow spheres after quenching. The morphology and crystal evolution are studied by means of X-ray diffraction and scanning electron microscopy. We found that after annealing at 250–400 °C, the sample consist of a mixture of magnetite, maghemite and hematite. Single hematite phase in the form of hollow microspheres is obtained after annealing at 550 and 600 °C. The crystallization and crystal size of the hematite shells increase with annealing temperature. A possible mechanism for hollow sphere formation is presented. - Highlights: • Formation of hollow hematite microspheres by the gas-bubble template method. • This technique does not require hard templates or special conditions of atmosphere. • Annealing promotes the transition magnetite to maghemite to hematite. • Crystallization of the hematite shells increase with annealing temperature.

  14. Iron Oxide Films Prepared by Rapid Thermal Processing for Solar Energy Conversion.

    Science.gov (United States)

    Wickman, B; Bastos Fanta, A; Burrows, A; Hellman, A; Wagner, J B; Iandolo, B

    2017-01-16

    Hematite is a promising and extensively investigated material for various photoelectrochemical (PEC) processes for energy conversion and storage, in particular for oxidation reactions. Thermal treatments during synthesis of hematite are found to affect the performance of hematite electrodes considerably. Herein, we present hematite thin films fabricated via one-step oxidation of Fe by rapid thermal processing (RTP). In particular, we investigate the effect of oxidation temperature on the PEC properties of hematite. Films prepared at 750 °C show the highest activity towards water oxidation. These films show the largest average grain size and the highest charge carrier density, as determined from electron microscopy and impedance spectroscopy analysis. We believe that the fast processing enabled by RTP makes this technique a preferred method for investigation of novel materials and architectures, potentially also on nanostructured electrodes, where retaining high surface area is crucial to maximize performance.

  15. The Cannery Formation--Devonian to Early Permian arc-marginal deposits within the Alexander Terrane, Southeastern Alaska

    Science.gov (United States)

    Karl, Susan M.; Layer, Paul W.; Harris, Anita G.; Haeussler, Peter J.; Murchey, Benita L.

    2011-01-01

    The Cannery Formation consists of green, red, and gray ribbon chert, siliceous siltstone, graywacke-chert turbidites, and volcaniclastic sandstone. Because it contains early Permian fossils at and near its type area in Cannery Cove, on Admiralty Island in southeastern Alaska, the formation was originally defined as a Permian stratigraphic unit. Similar rocks exposed in Windfall Harbor on Admiralty Island contain early Permian bryozoans and brachiopods, as well as Mississippian through Permian radiolarians. Black and green bedded chert with subordinate lenses of limestone, basalt, and graywacke near Kake on Kupreanof Island was initially correlated with the Cannery Formation on the basis of similar lithology but was later determined to contain Late Devonian conodonts. Permian conglomerate in Keku Strait contains chert cobbles inferred to be derived from the Cannery Formation that yielded Devonian and Mississippian radiolarians. On the basis of fossils recovered from a limestone lens near Kake and chert cobbles in the Keku Strait area, the age of the Cannery Formation was revised to Devonian and Mississippian, but this revision excludes rocks in the type locality, in addition to excluding bedded chert on Kupreanof Island east of Kake that contains radiolarians of Late Pennsylvanian and early Permian age. The black chert near Kake that yielded Late Devonian conodonts is nearly contemporaneous with black chert interbedded with limestone that also contains Late Devonian conodonts in the Saginaw Bay Formation on Kuiu Island. The chert cobbles in the conglomerate in Keku Strait may be derived from either the Cannery Formation or the Saginaw Bay Formation and need not restrict the age of the Cannery Formation, regardless of their source. The minimum age of the Cannery Formation on both Admiralty Island and Kupreanof Island is constrained by the stratigraphically overlying fossiliferous Pybus Formation, of late early and early late Permian age. Because bedded radiolarian

  16. Use of Fly Ash in the Mitigation of Alkali-Silica Reaction in Concrete

    Science.gov (United States)

    2010-11-12

    crystallinity of the silica and its solubility. Common reactive minerals susceptible to ASR include strained quartz, cristobalite, opal, obsidian , chert, and... obsidian .[5] Adequate Moisture Adequate moisture, the third and final necessary component for ASR to occur, is one of the key components in the

  17. 77 FR 19686 - Notice of Inventory Completion: U.S. Department of Defense, Army Corps of Engineers, Walla Walla...

    Science.gov (United States)

    2012-04-02

    ... beads and cordage; 1 chert flake; 9 copper tubular beads with cordage and cut dentalium shell; 8 copper... feet in diameter and contained human remains and a large amount of copper funerary objects. Burial 3... associated funerary objects are: 44 copper tubular beads; 1 antler digging stick handle; 222 copper tubular...

  18. Lower Cretaceous Xigaze ophiolites formed in the Gangdese forearc : Evidence from paleomagnetism, sediment provenance, and stratigraphy

    NARCIS (Netherlands)

    Huang, Wentao; van Hinsbergen, Douwe J J; Maffione, Marco; Orme, Devon A.; Dupont-Nivet, Guillaume; Guilmette, Carl; Ding, Lin; Guo, Zhaojie; Kapp, Paul

    2015-01-01

    The India-Asia suture zone of southern Tibet exposes Lower Cretaceous Xigaze ophiolites and radiolarian cherts, and time-equivalent Asian-derived clastic forearc sedimentary rocks (Xigaze Group). These ophiolites have been interpreted to have formed in the forearc of the north-dipping subduction

  19. 77 FR 59643 - Notice of Intent To Repatriate Cultural Items: San Francisco State University NAGPRA Program, San...

    Science.gov (United States)

    2012-09-28

    ... chert tools, 84 ground stone tools, 90 bone tools, 1 ear spool, and 4 earplugs. Radiometric dating... medicine pestle fragment, and 1 quartz crystal. The 147 objects of cultural patrimony are 12 ground stone... A.E. Treganza. The 4 sacred objects are 2 stone pestles to grind medicine or paint used in...

  20. 77 FR 59659 - Notice of Inventory Completion for Native American Human Remains and Associated Funerary Objects...

    Science.gov (United States)

    2012-09-28

    ... debitage, ground stone, and faunal materials, including modified and unmodified animal bones and teeth and... objects are a projectile point and a piece of flaked stone. In the Federal Register (65 FR 80957, December... associated funerary objects are 1 chert point and 48 pieces of flaked stone debitage. In the Federal Register...