262,372 research outputs found
XAS analysis of iron and palladium bonded to a polysaccharide produced anaerobically by a strain of Klebsiella oxytoca
No full textKlebsiella oxytoca BAS-10 ferments citrate to acetic acid and CO2 and secretes a specific exopolysaccharide (EPS), which is able to bind different metallic species. These biomaterials may be used for different biotechnological purposes, including applications as innovative green biogenerated catalysts. In production of biogenerated Pd species, the Fe(III) as ferric citrate is added to anaerobic culture of K. oxytoca BAS-10, in the presence of palladium species, to increase the EPS secretion and improve Pd-EPS yield. In this process, bi-metallic (FePd-EPS) biomaterials were produced for the first time. The morphology of bimetallic EPS, and the chemical state of the two metals in the FePd-EPS, are investigated by transmission electron microscopy, Fourier transform infra-red spectroscopy, micro-X-ray fluorescence, and X-ray absorption spectroscopy methods (XANES and EXAFS), and compared with mono-metallic Pd-EPS and Fe-EPS complexes. Iron in FePd-EPS is in the mineralized form of iron oxides/hydroxides, predominantly in the form of Fe3+, with a small amount of Fe2+ in the structure, most probably a mixture of different nano-crystalline iron oxides and hydroxides, as in mono-metallic Fe-EPS. Palladium is found as Pd(0) in the form of metallic nanoparticles with face-centred cubic structure in both bimetallic (FePd-EPS) and mono-metallic (Pd-EPS) species. In bi-metallic species, Pd and Fe nanoparticles agglomerate in larger clusters, but they remain spatially separated. The catalytic ability of bi-metallic species (FePd-EPS) in a hydrodechlorination reaction is improved in comparison with mono-metallic Pd-EPS
Soil humic acids may favour the persistence of hexavalent chromium in soil
No full textThe interaction between hexavalent chromium Cr(VI), as K(2)CrO(4), and standard humic acids (HAs) in bulk solution was studied using three complementary analytical methods: UV-Visible spectroscopy, X-ray absorption spectroscopy and differential pulse stripping voltammetry. The observed UV-Vis and X-ray absorption spectra showed that, under our experimental conditions, HAs did not induce reduction of Cr(VI) to its trivalent chemical form. The interaction between Cr(VI) and HAs has rather led to the formation of Cr(VI)-HAs micelles via supramolecular chemical processes. The reported results could contribute towards explaining the relative persistence of ecotoxic hexavalent chromium in soils
XAS analysis of a nanostructured iron polysaccharide produced anaerobically by a strain of Klebsiella oxytoca
No full textA strain of Klebsiella oxytoca, isolated from acid pyrite-mine drainage, characteristically produces a ferric hydrogel, consisting of branched heptasaccharide repeating units exopolysaccharide (EPS), with metal content of 36 wt%. The high content of iron in the EPS matrix cannot be explained by a simple ferric ion bond to the sugar skeleton. The bio-generated Fe-EPS is investigated by X-ray absorption spectroscopy. Fe K-edge XANES analysis shows that iron is mostly in trivalent form, with a nonnegligible amount of Fe 2+ in the structure. The Fe EXAFS results indicate that iron in the sample is in a mineralized form, prevalently in the form of nanosized particles of iron oxides/hydroxides, most probably a mixture of different nano-crystalline forms. TEM shows that these nanoparticles are located in the interior of the EPS matrix, as in ferritin. The strain produces Fe-EPS to modulate Fe-ions uptake from the cytoplasm to avoid iron toxicity under anaerobic conditions. This microbial material is potentially applicable as iron regulator. © Springer Science+Business Media, LLC. 2012
Interactions between Fe-cyanide complex and humic acids
No full textThe fate of cyanides in soil is strongly influenced
by the formation of Fe cyanides, which can interact with
organic and inorganic colloids and precipitate as stable
compounds. Scarce information is available on the capacity
of humic acids to interact with cyano-complexes and thus
affect the leaching and prevent the risk of contamination of
watertable. Here we show that interaction between humic
acids (HAs) and ferricyanide complex led to a formation
of ferricyanide-humo micelles, and that the interaction did
not imply changes in the original structure of ferricyanide
comple
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
ARCON: experience in 215 patients with advanced head-and-neck cancer.
No full textContains fulltext :
142773.pdf (Publisher’s version ) (Open Access)PURPOSE: "ARCON" combines accelerated radiotherapy to counteract tumor repopulation with carbogen breathing and nicotinamide to reduce chronic and acute hypoxia. The aim of this Phase II study was to assess the feasibility, toxicity, and potential effectiveness of ARCON for advanced head-and-neck cancer. METHODS AND MATERIALS: The study included 215 patients with head-and-neck carcinoma distributed as follows: larynx, n = 100; hypopharynx, n = 50; oropharynx, n = 52; oral cavity, n = 13; Stage II, n = 8, Stage III, n = 71, and Stage IV, n = 136. Accelerated radiotherapy was given to a total dose of 64-68 Gy in 2-Gy fractions within 36-38 days. This was combined with carbogen breathing during irradiation and administration of nicotinamide (60-80 mg/kg) 1-1.5 h before irradiation. RESULTS: There was full compliance with carbogen breathing in 88% of the patients. A nicotinamide dose of 80 mg/kg produced severe nausea and vomiting, necessitating discontinuation of the drug, in 31% of the patients. Adjustment of the dose to 60 mg/kg and antiemesis prophylaxis reduced the discontinuation rate to 10%. Confluent mucositis was observed in 91% of the patients with a median duration of 6 weeks. Grade 4 late complications occurred in 5% of the patients. The actuarial 3-year local control rates were 80% for larynx, 69% for hypopharynx, 88% for oropharynx, and 37% for oral cavity tumors. For T3-4 tumors, the local control rates were 80% for larynx, 60% for hypopharynx, 87% for oropharynx, and 29% for oral cavity. Regional control rates were 100% for N0, 93% for N1, and 74% for N2 disease. CONCLUSION: ARCON yields high local and regional control rates in advanced head-and-neck carcinomas, and compliance is satisfactory and morbidity acceptable. The local control rate of 80% for T3 and T4 larynx carcinomas offers excellent possibilities for organ preservation
Protecting Animals 36: Author Witi Ihimaera
No full textIn this very special episode of Knowing Animals I am joined by beloved New Zealand author Witi Ihimaera. Witi has written many books featuring nonhuman animals. He offers us a non-colonial lens through which to think about the human/nonhuman relationship
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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