Allophanic and ferric root-associated stalactites: biomineralization induced by microbial activity (Galeria da Queimada lava tube, Terceira, Azores)

AbstractRoot-associated stalactites (rootsicles) in Galeria da Queimada lava tube have a mineralogical composition and developmental association with microbes that render them unique. Samples were examined by X-ray diffraction, micro-Raman spectrometry and scanning electron microscopy/X-ray energy-dispersive spectroscopy. Three types of rootsicle were defined: incipient; hard (white and red); and black spongy. The incipient rootsicles still contained rotten organic material and showed the beginning of mineralization by allophane. The white hard and black spongy types were also composed of allophane, while the red hard type was composed of hydrous ferric oxi-hydroxide minerals (HFO). The allophane and HFO in the andisol covering the cave roof precipitated out of the dripwater running along the roots to form the studied rootsicles. All three types of rootsicle showed black layers, coatings, spots or patches composed of manganese oxide minerals and, occasionally, hisingerite (iron (III) phyllosilicate). An alternation of organic precipitation caused by filamentous bacteria and inorganic precipitation (the latter facilitated by pH changes in the dripwater and the cave's temperature) built up both the porous and compact rings observed in the white and red hard rootsicles. The largely straight filaments seen in the porous rings of the white hard rootsicles may be indicative of the previous presence ofLeptothrixspp., while the helical morphologies seen in the red hard rootsicles may be indicative of that ofGallionellaspp. The manganese oxide minerals detected probably formed via microbial activity. This study reflects the important role of filamentous bacteria in rootsicle formation, independent of their mineralogy.

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Sedimentary Clays as Geopolymer Precursor

International Journal of Engineering Research in Africa ◽

10.4028/www.scientific.net/jera.39.97 ◽

2018 ◽

Vol 39 ◽

pp. 97-111

Author(s):

F. Mostefa ◽

Nasr Eddine Bouhamou ◽

H.A. Mesbah ◽

Salima Aggoun ◽

D. Mekhatria

Keyword(s):

Sodium Hydroxide ◽

Mineralogical Composition ◽

Cementitious Materials ◽

Raw Material ◽

X Ray Diffraction ◽

Calcination Time ◽

Calorimetric Analysis ◽

X Ray ◽

Before And After ◽

Mechanical Performances

This work aims to study the feasibility of making a geopolymer cement based on dredged sediments, from the Fergoug dam (Algeria) and to evaluate their construction potential particularly interesting in the field of special cementitious materials. These sediments due to their mineralogical composition as aluminosilicates; are materials that can be used after heat treatment. Sedimentary clays were characterized before and after calcination by X-ray diffraction, ATG / ATD, spectroscopy (FTIR) and XRF analysis. The calcination was carried out on the raw material sieved at 80 μm for a temperature of 750 ° C, for 3.4 and 5 hours. The reactivity of the calcined products was measured using isothermal calorimetric analysis (DSC) on pastes prepared by mixing an alkaline solution of sodium hydroxide (NaOH) 8 M in an amount allowing to have a Na / Al ratio close to 1 (1: 1). Also, cubic mortar samples were prepared with a ratio L / S: 0.8, sealed and cured for 24 hours at 60 ° C and then at room temperature until the day they were submited to mechanical testing. to check the extent of geopolymerization. The results obtained allowed to optimize the calcination time of 5 hours for a better reactivity of these sediments, and a concentration of 8M of sodium hydroxide and more suitable to have the best mechanical performances.

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Crystallization of simonkolleite (Zn5Cl2(OH)8 ∙ H2O) in powder samples prepared for mineral composition analysis by quantitative X-ray diffraction (QXRD)

Nafta-Gaz ◽

10.18668/ng.2021.05.02 ◽

2021 ◽

Vol 77 (5) ◽

pp. 293-298

Author(s):

Urszula Zagórska ◽

◽

Sylwia Kowalska ◽

Keyword(s):

Quantitative Analysis ◽

Internal Standard ◽

Mineralogical Composition ◽

Hydrocarbon Exploration ◽

Composition Analysis ◽

Internal Standard Method ◽

X Ray Diffraction ◽

Method Error ◽

X Ray ◽

Significant Difference

The analysis of mineralogical composition by quantitative X-ray diffraction (QXRD) is one of the standard research methods used in hydrocarbon exploration. In order to improve it and to obtain better results, the methodology of quantitative analysis used at Well Logging Department is being periodically (more or less) modified. After the introduction of the improvements, comparative analyses were performed on archival samples. Reflections from an unidentified phase which did not occur in the tested Rotliegend sandstone samples were noticed on X-ray diffractograms of archival samples. Reflections of a mineral called simonkolleite were identified in the X-ray diffraction database. Chemically it is a hydrated zinc chloride of the formula: Zn5Cl2(OH)8 × H2O. Analysis of the composition of samples in which simonkolleite crystallised, indicated that the mineral is being formed in the result of the slow reaction of zinc oxide with halite (NaCl) and water vapour. An attempt was made to determine the influence of the presence of this mineral on the results of the quantitative analysis of mineralogical composition. The above methodology was applied on a group of ten samples. The results of the quantitative analysis conducted for archival samples stored with added zincite standard containing simonkolleite and for new, freshly grinded (without artifact) samples were compared. The comparison of the obtained results showed a slight influence of this mineral on the quantitative composition of the remaining components. The difference between the results usually did not exceed the method error. At the same time a significant difference in the calculated content of the internal standard was noted – on average 1% less in archival than in new samples. This shows that the reaction occurring in the archival samples will affect the evaluation of the quality of the obtained quantitative analysis, at the same time excluding the possibility of determining the rock’s amorphous substance content with the internal standard method.

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A prototype handheld X-ray diffraction instrument

Journal of Applied Crystallography ◽

10.1107/s1600576718012943 ◽

2018 ◽

Vol 51 (6) ◽

pp. 1571-1585 ◽

Cited By ~ 1

Author(s):

Graeme Hansford

Keyword(s):

Sample Preparation ◽

Mineralogical Composition ◽

General Purpose ◽

Performance Criteria ◽

X Ray Diffraction ◽

X Ray ◽

Fine Grained ◽

Back Reflection ◽

Promising Area ◽

Sample Position

A conceptual design for a handheld X-ray diffraction (HHXRD) instrument is proposed. Central to the design is the application of energy-dispersive XRD (EDXRD) in a back-reflection geometry. This technique brings unique advantages which enable a handheld instrument format, most notably, insensitivity to sample morphology and to the precise sample position relative to the instrument. For fine-grained samples, including many geological specimens and the majority of common alloys, these characteristics negate sample preparation requirements. A prototype HHXRD device has been developed by minor modification of a handheld X-ray fluorescence instrument, and the performance of the prototype has been tested with samples relevant to mining/quarrying and with an extensive range of metal samples. It is shown, for example, that the mineralogical composition of iron-ore samples can be approximately quantified. In metals analysis, identification and quantification of the major phases have been demonstrated, along with extraction of lattice parameters. Texture analysis is also possible and a simple example for a phosphor bronze sample is presented. Instrument formats other than handheld are possible and online process control in metals production is a promising area. The prototype instrument requires extended measurement times but it is argued that a purpose-designed instrument can achieve data-acquisition times below one minute. HHXRD based on back-reflection EDXRD is limited by the low resolution of diffraction peaks and interference by overlapping fluorescence peaks and, for these reasons, cannot serve as a general-purpose XRD tool. However, the advantages ofin situ, nondestructive and rapid measurement, tolerance of irregular surfaces, and no sample preparation requirement in many cases are potentially transformative. For targeted applications in which the analysis meets commercially relevant performance criteria, HHXRD could become the method of choice through sheer speed and convenience.

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The mineralogy and firing behaviour of pottery clays of the Lake Van region, eastern Turkey

Clay Minerals ◽

10.1180/claymin.2017.052.4.04 ◽

2017 ◽

Vol 52 (4) ◽

pp. 453-468 ◽

Cited By ~ 2

Author(s):

A. Aras ◽

S. Kiliç

Keyword(s):

East Coast ◽

Chemical Characterization ◽

Mineralogical Composition ◽

Lake Van ◽

X Ray Diffraction ◽

Pottery Production ◽

X Ray ◽

Different Types ◽

Firing Shrinkage

AbstractThe present study focused on the mineralogical and chemical characterization and firing behaviour of clays from the Lake Van region and compared them with the same characteristics established for two ancient pot sherds. Four pottery clays collected from Kutki and Kuşluk in the Kesan Valley to the south, from Kavakbaşı to the southwest and from Bardakçı village on the east coast of Lake Van were analysed by X-ray diffraction to identify mineralogical composition (bulk clays and <2 μm fractions after heating at 300–500°C and ethylene glycol solvation). Further analyses were conducted to determine the size distribution, chemical composition and physical properties of test bodies derived from these clays. The in situ weathered schist forming the primary micaceous red clays which are suitable for local pottery production are characterized by large muscovite-sericite-illite and small calcite contents. In contrast, the Bardakçı clays are dominated by large smectite contents and are only used sparingly in mixtures of local pottery production because they undergo firing shrinkage and present drying and firing flaws in the fired bodies. Firing ranges of ~800–900°C were inferred from the mineralogy and colours of the two ancient sherds from Kutki. As a result of mineralogical analysis of fired and unfired test bodies of these pottery clays and pot sherds, two different types of pastes were determined for pottery production in the Lake Van region: metamorphic and volcanic paste, the former characterized by a calcite-poor and mica-sericite-rich matrix and the latter by large smectite and small calcite contents.

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Arsenite Oxidation by a Poorly Crystalline Manganese-Oxide. 2. Results from X-ray Absorption Spectroscopy and X-ray Diffraction

Environmental Science & Technology ◽

10.1021/es102016c ◽

2010 ◽

Vol 44 (22) ◽

pp. 8467-8472 ◽

Cited By ~ 131

Author(s):

Brandon J. Lafferty ◽

Matthew Ginder-Vogel ◽

Mengqiang Zhu ◽

Kenneth J. T. Livi ◽

Donald L. Sparks

Keyword(s):

Manganese Oxide ◽

Absorption Spectroscopy ◽

X Ray Diffraction ◽

Arsenite Oxidation ◽

X Ray ◽

X Ray Absorption

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X-ray diffraction and impedance spectroscopy studies of lithium manganese oxide spinel

Journal of Power Sources ◽

10.1016/j.jpowsour.2006.02.033 ◽

2006 ◽

Vol 159 (1) ◽

pp. 412-419 ◽

Cited By ~ 2

Author(s):

M. Kopeć ◽

D. Lisovytskiy ◽

M. Marzantowicz ◽

J.R. Dygas ◽

F. Krok ◽

...

Keyword(s):

Impedance Spectroscopy ◽

Manganese Oxide ◽

Lithium Manganese Oxide ◽

X Ray Diffraction ◽

X Ray ◽

Lithium Manganese ◽

Oxide Spinel ◽

Lithium Manganese Oxide Spinel ◽

Spectroscopy Studies

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The manganese oxide mineral, lithiophorite, in an oxisol From Hawaii

Soil Research ◽

10.1071/sr9930051 ◽

1993 ◽

Vol 31 (1) ◽

pp. 51 ◽

Cited By ~ 19

Author(s):

DC Golden ◽

JB Dixon ◽

Y Kanehiro

Keyword(s):

Electron Microscopy ◽

Clay Fraction ◽

Hydroxylamine Hydrochloride ◽

Mineralogical Composition ◽

Soil Horizon ◽

X Ray Diffraction ◽

High Gradient Magnetic Separation ◽

X Ray ◽

Tropeptic Eutrustox ◽

Treated Sample

The mineralogical composition of the surface soil horizon (0-15 cm) of Wahiawa soil (Tropeptic Eutrustox) was investigated by X-ray diffraction (XRD), high gradient magnetic separation (HGMS), transmission electron microscopy (TEM), and infrared methods. The concentration of lithiophorite decreased with particle size and none was present in the clay fraction as indicated by XRD. Lithiophorite was further concentrated from the crushed sand-sized fraction by HGMS. Hexagonal, electron-dense, often twinned lithiophorite particles were identified by electron diffraction. Differential infrared (DIR) spectra obtained by dissolving Mn oxides in acidified hydroxylamine hydrochloride (HAHC) indicated lithiophorite as the HAHC-soluble Mn-phase. Lithiophorite compositiion, as revealed by chemical analysis of the HAHC extracts, consisted of appreciable amounts of Mn, Al, Zn, Co and Mg, and less than stoichiometric amounts of Li. Sodium hydroxide treatment apparently altered the lithiophorite, as revealed by the DIR spectrum of the hydroxylamine-soluble fraction of the NaOH-treated sample compared with the untreated sample. The high crystallinity of the lithiophorite was suggested by its resistance to chemical dissolution and narrow X-ray diffraction lines. No evidence for the presence of todorokite or birnessite was found, contrary to earlier reports. Examination of sand-sized nodules by scanning electron microscopy indicated large (2-5 �m) platy lithiophorite crystals at the surface of these nodules. Electron microprobe analysis of these platy particles indicated iron enrichment near the surface. The freshly fractured nodule surface revealed numerous unaltered platy crystals of lithiophorite filling the veins of the nodule.

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Preparation, Characterization and Intermediate-Temperature Electrochemical Properties of Er3+-Doped Barium Cerate–Sulphate Composite Electrolyte

Materials ◽

10.3390/ma12172752 ◽

2019 ◽

Vol 12 (17) ◽

pp. 2752

Author(s):

Fufang Wu ◽

Ruifeng Du ◽

Tianhui Hu ◽

Hongbin Zhai ◽

Hongtao Wang

Keyword(s):

Maximum Output Power ◽

Nitrogen Atmosphere ◽

Maximum Output ◽

Barium Cerate ◽

X Ray Diffraction ◽

Ac Impedance Spectroscopy ◽

Raman Spectrometry ◽

Composite Electrolyte ◽

X Ray ◽

Doped Barium Cerate

In this study, BaCe0.9Er0.1O3−α was synthesized by a microemulsion method. Then, a BaCe0.9Er0.1O3−α–K2SO4–BaSO4 composite electrolyte was obtained by compounding it with a K2SO4–Li2SO4 solid solution. BaCe0.9Er0.1O3−α and BaCe0.9Er0.1O3−α–K2SO4–BaSO4 were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Raman spectrometry. AC impedance spectroscopy was measured in a nitrogen atmosphere at 400–700 °C. The logσ~log (pO2) curves and fuel cell performances of BaCe0.9Er0.1O3−α and BaCe0.9Er0.1O3−α–K2SO4–BaSO4 were tested at 700 °C. The maximum output power density of BaCe0.9Er0.1O3−α–K2SO4–BaSO4 was 115.9 mW·cm−2 at 700 °C, which is ten times higher than that of BaCe0.9Er0.1O3−α.

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Novel Bovine Serum Albumin Protein Backbone Reassembly Study: Strongly Twisted β-Sheet Structure Promotion upon Interaction with GO-PAMAM

Polymers ◽

10.3390/polym12112603 ◽

2020 ◽

Vol 12 (11) ◽

pp. 2603

Author(s):

Andra Mihaela Onaș ◽

Iuliana Elena Bîru ◽

Sorina Alexandra Gârea ◽

Horia Iovu

Keyword(s):

Secondary Structure ◽

Bovine Serum Albumin ◽

Serum Albumin ◽

Bovine Serum ◽

Infrared Spectrometry ◽

X Ray Diffraction ◽

Protein Backbone ◽

Raman Spectrometry ◽

X Ray ◽

Β Sheet

This study investigates the formation of a graphene oxide-polyamidoamine dendrimer complex (GO-PAMAM) and its association and interaction with bovine serum albumin (BSA). Fourier-transform infrared spectrometry and X-ray photoelectron spectrometry indicated the formation of covalent linkage between the GO surface and PAMAM with 7.22% nitrogen content in the GO-PAMAM sample, and various interactions between BSA and GO-PAMAM, including π-π* interactions at 291.5 eV for the binding energy value. Thermogravimetric analysis highlighted the increasing thermal stability throughout the modification process, from 151 to 192 °C for the 10% weight loss temperature. Raman spectrometry and X-ray diffraction analysis were used in order to examine the complexes’ assembly, showing a prominent (0 0 2) lattice in GO-PAMAM. Dynamic light scattering tests proved the formation of stable graphenic and graphenic-protein aggregates. The secondary structure rearrangement of BSA after interaction with GO-PAMAM was investigated using circular dichroism spectroscopy. We have observed a shift from 10.9% β-sheet composition in native BSA to 64.9% β-sheet composition after the interaction with GO-PAMAM. This interaction promoted the rearrangement of the protein backbone, leading to strongly twisted β-sheet secondary structure architecture.

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