scholarly journals Geochemical and sedimentary constraints on the formation of the Venta Micena early Pleistocene site (Guadix-Baza Basin, Spain)

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Alejandro Granados ◽  
Oriol Oms ◽  
Pere Anadón ◽  
Jordi Ibáñez-Insa ◽  
Anu Kaakinen ◽  
...  
Keyword(s):  
Critical Role ◽  
Freshwater Wetlands ◽  
Freshwater Wetland ◽  
Early Pleistocene ◽  
Bulk Rock ◽  
X Ray Diffraction ◽  
Marginal Areas ◽  
Invertebrate Fossils ◽  
Venta Micena ◽  
Lake Dynamics

AbstractDespite the paleontological relevance of the terrestrial Early Pleistocene Venta Micena bonebed (Baza Basin, Spain), it lacks a comprehensive geochemical/sedimentological study. Here, we demonstrate that the 1.5-m-thick Venta Micena limestone formed in a relatively small freshwater wetland/pond located at the periphery of the large saline Baza paleolake. Two microfacies are observed, with high and low contents of invertebrate fossils, and which originated in the centre and margin of the wetland, respectively. X-ray diffraction (XRD) mineralogy and paleohydrological characterization based on ostracod and bulk-rock geochemistry (δ13C and δ18O) indicate that the limestone reflects a general lowstand of the Baza lake, permitting the differentiation of freshwater wetlands that were fed by adjacent sources. Conversely, during highstands, the Baza lake flooded the Venta Micena area and the freshwater fauna was replaced by a saline one. Bulk-rock isotopic data indicate that the lower interval C1 of the limestone (bone-rich in marginal settings) displays general negative values, while the upper interval C2 (bone free) displays less negative values. The bones of predated mammals accumulated in the marginal areas, which were flooded and buried by recurring water-table fluctuations. Lake dynamics played a critical role in bone accumulation, which was previously considered as representing a hyena den.

scholarly journals Provenance and Sedimentary Context of Clay Mineralogy in an Evolving Forearc Basin, Upper Cretaceous-Paleogene and Eocene Mudstones, San Joaquin Valley, California

Minerals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 71
Author(s):  
Andrew Hurst ◽  
Michael Wilson ◽  
Antonio Grippa ◽  
Lyudmyla Wilson ◽  
Giuseppe Palladino ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Upper Cretaceous ◽  
Clay Fraction ◽  
Clay Mineralogy ◽  
Bulk Rock ◽  
X Ray Diffraction ◽  
Arc Volcanism ◽  
X Ray ◽  
Magmatic Arc ◽  
Tropical Weathering

Mudstone samples from the Moreno (Upper Cretaceous-Paleocene) and Kreyenhagen (Eocene) formations are analysed using X-ray diffraction (XRD) and X-ray fluorescence (XRF) to determine their mineralogy. Smectite (Reichweite R0) is the predominant phyllosilicate present, 48% to 71.7% bulk rock mineralogy (excluding carbonate cemented and highly bio siliceous samples) and 70% to 98% of the <2 μm clay fraction. Opal CT and less so cristobalite concentrations cause the main deviations from smectite dominance. Opal A is common only in the Upper Kreyenhagen. In the <2 μm fraction, the Moreno Fm is significantly more smectite-rich than the Kreyenhagen Fm. Smectite in the Moreno Fm was derived from the alteration of volcaniclastic debris from contemporaneous rhyolitic-dacitic magmatic arc volcanism. No tuff is preserved. Smectite in the Kreyenhagen Fm was derived from intense sub-tropical weathering of granitoid-dioritic terrane during the hypothermal period in the early to mid-Eocene; the derivation from local volcanism is unlikely. All samples had chemical indices of alteration (CIA) indicative of intense weathering of source terrane. Ferriferous enrichment and the occurrence of locally common kaolinite are contributory evidence for the intensity of weathering. Low concentration (max. 7.5%) of clinoptilolite in the Lower Kreyenhagen is possibly indicative of more open marine conditions than in the Upper Kreyenhagen. There is no evidence of volumetrically significant silicate diagenesis. The main diagenetic mineralisation is restricted to low-temperature silica phase transitions.

Metal-Controlled Assembly Tuning Coordination Polymers with Flexible 2-(1H-imidazole-1-yl)acetic Acid (Hima)

2006 ◽  
Vol 59 (9) ◽  
pp. 647 ◽  
Author(s):  
Yong-Tao Wang ◽  
Gui-Mei Tang ◽  
Da-Wei Qin
Keyword(s):  
Coordination Polymers ◽  
Weak Interactions ◽  
Critical Role ◽  
Three Dimensional ◽  
Supramolecular Network ◽  
Water Medium ◽  
New Materials ◽  
X Ray Diffraction ◽  
X Ray ◽  
Supramolecular Networks

Three new inorganic–organic coordination polymers based on a versatile linking unit 2-(1H-imidazole-1-yl)acetate (Hima) and divalent Mn(ii), Ni(ii), and Cu(ii) ions, exhibiting two kinds of two dimensionalities with different topological structures, have been prepared in water medium and structurally characterized by single-crystal X-ray diffraction analysis. Reaction of MnCl2·4H2O and Ni(NO3)2·6H2O with Hima yielded neutral two-dimensional (2D) coordination polymers [M(ima)2]n, M = Mn(ii) 1, and Ni(ii) 2 with isostructural 2D coordination polymers possessing (3,6) topology structures, which further stack into three-dimensional (3D) supramolecular networks through C–H···O weak interactions. However, when Cu(NO3)2·4H2O was used, a neutral 2D coordination polymer [Cu(ima)2]n 3 consisting of rhombus units was generated, which showed a 3D supramolecular network through C–H···O weak interactions. Among these polymers, the building block ima anion exhibits different coordination modes. These results indicate that the versatile nature of this flexible ligand, together with the coordination preferences of the metal ions, plays a critical role in construction of these novel coordination polymers. Spectral and thermal properties of these new materials have also been investigated.

CONTROLLED SYNTHESIS AND CHARACTERIZATION OF TiO2 NANOPARTICLES VIA A SOL–GEL METHOD

2004 ◽  
Vol 03 (06) ◽  
pp. 749-755 ◽  
Author(s):  
YING LI ◽  
SUO HON LIM ◽  
TIM WHITE
Keyword(s):  
Sol Gel ◽  
Critical Role ◽  
Rietveld Analysis ◽  
Nanocrystalline Powders ◽  
X Ray Diffraction ◽  
Gelation Temperature ◽  
Gel Method ◽  
Sol Gel Method ◽  
Transmission Electron

The properties influencing the photocatalytic activity of TiO 2 particles have been suggested to include the surface area, crystallinity, crystallite size and crystal structure. Therefore, manipulation of the microstructure of titania, especially of nanocrystalline powders, is very important in the preparative process. In this study, nanocrystalline TiO 2 powders with controlled particle size and phase composition were synthesized at low temperature (<80°C) by a modified sol–gel method. The effects of gelation temperature were systematically investigated. It was found that this parameter played a critical role in determining the crystallinity of single phase anatase. With increasing gelation temperature, the crystallinity of anatase improved initially and then decreased if the temperature was raised to 80°C. These nanomaterials were characterized comprehensively by powder X-ray diffraction (including Rietveld analysis), high-resolution transmission electron microscopy, DSC/TGA thermal analysis and UV–Vis spectrometry.

scholarly journals X-ray Crystallographic Study of Ranaconitine

2011 ◽  
Vol 6 (11) ◽  
pp. 1934578X1100601
Author(s):  
Yang Li ◽  
Jun-Hui Zhou ◽  
Gui-Jun Han ◽  
Min-Juan Wang ◽  
Wen-Ji Sun ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Diffraction Analysis ◽  
Critical Role ◽  
X Ray Diffraction ◽  
Monoclinic System ◽  
X Ray ◽  
Crystallographic Study ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

The crystal structure of natural diterpenoid alkaloid ranaconitine isolated from Aconitum sinomontanum Nakai has been determined by single crystal X-ray diffraction analysis. The crystal presents a monoclinic system, space group C2 with Z = 4, unit cell dimensions a = 30.972(19) Å, b = 7.688(5) Å, and c = 19.632(12) Å. Moreover, the intermolecular O–H···O hydrogen bonds and weak π-π interactions play a critical role in expanding the dimensionality.

scholarly journals Gnidia glauca- and Plumbago zeylanica-Mediated Synthesis of Novel Copper Nanoparticles as Promising Antidiabetic Agents

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Dhiraj A. Jamdade ◽  
Dishantsingh Rajpali ◽  
Komal A. Joshi ◽  
Rohini Kitture ◽  
Anuja S. Kulkarni ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Copper Nanoparticles ◽  
Critical Role ◽  
Cost Effective ◽  
Significant Inhibition ◽  
Antidiabetic Activity ◽  
X Ray Diffraction ◽  
One Pot ◽  
Plumbago Zeylanica ◽  
Transmission Electron

Rapid, eco-friendly, and cost-effective one-pot synthesis of copper nanoparticles is reported here using medicinal plants like Gnidia glauca and Plumbago zeylanica. Aqueous extracts of flower, leaf, and stem of G. glauca and leaves of P. zeylanica were prepared which could effectively reduce Cu2+ ions to CuNPs within 5 h at 100°C which were further characterized using UV-visible spectroscopy, field emission scanning electron microscopy, high-resolution transmission electron microscopy, energy dispersive spectroscopy, dynamic light scattering, X-ray diffraction, and Fourier-transform infrared spectroscopy. Further, the CuNPs were checked for antidiabetic activity using porcine pancreatic α-amylase and α-glucosidase inhibition followed by evaluation of mechanism using circular dichroism spectroscopy. CuNPs were found to be predominantly spherical in nature with a diameter ranging from 1 to 5 nm. The phenolics and flavonoids in the extracts might play a critical role in the synthesis and stabilization process. Significant change in the peak at ∼1095 cm−1 corresponding to C-O-C bond in ether was observed. CuNPs could inhibit porcine pancreatic α-amylase up to 30% to 50%, while they exhibited a more significant inhibition of α-glucosidase from 70% to 88%. The mechanism of enzyme inhibition was attributed due to the conformational change owing to drastic alteration of secondary structure by CuNPs. This is the first study of its kind that provides a strong scientific rationale that phytogenic CuNPs synthesized using G. glauca and P. zeylanica can be considered to develop candidate antidiabetic nanomedicine.

Microbial activity and diversity in the rhizosphere soil of the invasive species Zizania latifolia in the wetland of Wuchang Lake, China

2020 ◽  
Vol 71 (12) ◽  
pp. 1702
Author(s):  
Baohua Zhou ◽  
Zhaowen Liu ◽  
Guo Yang ◽  
Hui He ◽  
Haijun Liu
Keyword(s):  
Invasive Species ◽  
Rhizosphere Soil ◽  
Remote Sensing Data ◽  
Wetland Loss ◽  
Freshwater Wetlands ◽  
Total Carbon ◽  
Freshwater Wetland ◽  
Available Nitrogen ◽  
Zizania Latifolia ◽  
Rhizosphere Soils

Information about the consequences of invasive species overgrowing freshwater wetlands is limited. According to remote sensing data, the invasive species Zizania latifolia spreads at an annual rate of 1.78km2 in the freshwater wetland of Wuchang Lake, China, resulting in wetland loss and degradation due to the overgrowth. This species not only increases soil organic matter, total carbon, total nitrogen, total sulfate, available nitrogen and the C/N ratio in the rhizosphere soil, but also results in increased urease, sucrose and catalase activity, as well as fluorescein diacetate hydrolysis. In this study, we have analysed microbial diversity in rhizosphere soils among different habitat types of Z. latifolia. Microbial communities in different habitats invaded by Z. latifolia differed considerably at the genus level, although all soil samples were predominated by the phyla Proteobacteria, Acidobacteria and Chloroflexi. The dominant bacterial taxa in the rhizosphere soil from the floating blanket included Acidimicrobiales, Thiomonas, Alicyclobacillus, Acetobacteraceae and Acidocella, whereas those in rhizosphere soils from the lake sludge were Acidobacteria, Anaerolineaceae, Bacteroidetes and Nitrospirae. The bacterial community in the rhizosphere soil differed significantly from that in the non-rhizosphere soil. Z. latifolia potentially creates suitable habitats and provides substrate for a unique set of microbes, further facilitating the succession of this species.

The Properties of Modified Polysulfonamide Fabrics with Lamellar Magnesium Hydroxide Crystals

2013 ◽  
Vol 8 (2) ◽  
pp. 155892501300800
Author(s):  
Hui Ma ◽  
Linping Zhang ◽  
Hong Xu ◽  
Dan Wang ◽  
Xiaoyan Zhang ◽  
...  
Keyword(s):  
Magnesium Hydroxide ◽  
Inductively Coupled Plasma ◽  
Heat Insulation ◽  
Critical Role ◽  
Atomic Absorption Spectrometer ◽  
X Ray Diffraction ◽  
X Ray ◽  
Inductively Coupled ◽  
Carboxylic Acid Groups ◽  
Flammability Test

Lamellar magnesium hydroxide crystals were prepared successfully on the surface of polysulfonamide fibers with carboxylic acid groups. The polysulfonamide fabrics with Mg(OH)2 crystals were characterized by Scanning electron microscopy, Inductively coupled plasma atomic absorption spectrometer X-ray diffraction, Vertical flammability test and Thermalgravimetric analysis. The vertical flammability test showed that the damaged length of original polysulfonamide fabrics was 34mm, while that of the polysulfonamide fabrics with Mg(OH)2 crystals (treated by 7.5% NaOH solutions) was 14mm. In addition, the Mg (OH)2 crystals played a critical role in the improvement of thermal stability and heat insulation of polysulfonamide fabrics.

A Review of Recent Results on Single Crystal Metastable Semiconducfors: Crystal Growth, Phase Stability, and Physical Properties

1984 ◽  
Vol 37 ◽  
Author(s):  
S. A. Barnett ◽  
B. Kramer ◽  
L. T. Romano ◽  
S. I. Shah ◽  
M. A. Ray ◽  
...  
Keyword(s):  
Physical Properties ◽  
Single Crystal ◽  
Film Growth ◽  
Critical Role ◽  
Range Order ◽  
X Ray Diffraction ◽  
Ion Energy ◽  
Preferential Sputtering ◽  
Pseudobinary Phase Diagram ◽  
Semiconducting Alloys

AbstractRecent results on metastable semiconducting alloys, concerning in particular the growth of new Sn-based alloys (GaSb)1−x(Sn2)x and Gel−xSnx and the physical properties of (GaAs)1−x(Ge2)x and (GaSb)1−x(Ge2)x, are discussed. (GaSb)1−x(Sn2)x and Ge1−xSnx alloy films were grown with x-values as high as 0.20 and 0.15, respectively, well in excess of equilibrium Sn solid solubility limits (<1%) while epitaxial (GaAs)1−x(Ge2) and (GaSb)1−x(Ge2)x alloys were obtained on (100) GaAs at compositions ranging across the pseudobinary phase diagram. Low energy ion bombardment induced collisional mixing and preferential sputtering during film growth played a critical role in obtaining single phase alloys. An optimal ion energy, which depended on the ion flux and the alloy composition, was determined, allowing in most cases growth at temperatures T, sufficient for obtaining single crystal alloys on (100) GaAs and (100) Ge substrates. Decomposition of the Sn-based alloys occurred above a critical Ts- value via α-Sn-rich precipitates which were stable above the β-Sn melting point. X-ray diffraction, STEM, EXAFS, and Raman spectroscopy measurements, performed on single crystal (GaAs)1−x(Ge2)x and (GaSb)1−x(Ge2)x alloys, indicate that there is a transition in the long-range order from zincblende to diamond with increasing x while the short-range order remains perfect at all compositions, i.e. no V-V or III-Ill bonds are observed. These results are discussed in light of recent models which relate (GaAs)1−x(Ge2)x atomic structure to its band structure and optical properties.

Equilibrium phase diagrams in the system CuO–PbO–Ag

1995 ◽  
Vol 10 (11) ◽  
pp. 2933-2937 ◽  
Author(s):  
H.K. Liu ◽  
S.X. Dou ◽  
M. Ionescu ◽  
Z.B. Shao ◽  
K.R. Liu ◽  
...  
Keyword(s):  
High Temperature Superconductor ◽  
Eutectic Reaction ◽  
Critical Role ◽  
Equilibrium Phase ◽  
Eutectic Point ◽  
X Ray Diffraction ◽  
X Ray ◽  
Liquid Phases ◽  
Tie Lines ◽  
Xrd Techniques

Silver has played a critical role for the fabrication of metal/high temperature superconductor composites. Phase equilibrium and microstructure in the ternary PbO-CuO-Ag system have been investigated using differential thermal analysis (DTA), thermogravimetry (TG), scanning electron microscope (SEM), and x-ray diffraction (XRD) techniques. Composition versus temperature diagrams have been established for these systems in air. In the ternary CuO-PbO-Ag system, there is a eutectic reaction CuO + PbO + Ag = L at 750 °C and a composition of 12.04 mol % Ag, 16.35 mol % CuO, and 72.62 mol % PbO. Two immiscible regions near the two binary tie lines PbO-Ag and CuO-Ag were detected. No binary or ternary compound was detected in these systems. SEM and EDS results confirm the presence of two liquid phases and the eutectic point

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