A role for iron and oxygen chemistry in preserving soft tissues, cells and molecules from deep time

The persistence of original soft tissues in Mesozoic fossil bone is not explained by current chemical degradation models. We identified iron particles (goethite-αFeO(OH)) associated with soft tissues recovered from two Mesozoic dinosaurs, using transmission electron microscopy, electron energy loss spectroscopy, micro-X-ray diffraction and Fe micro-X-ray absorption near-edge structure. Iron chelators increased fossil tissue immunoreactivity to multiple antibodies dramatically, suggesting a role for iron in both preserving and masking proteins in fossil tissues. Haemoglobin (HB) increased tissue stability more than 200-fold, from approximately 3 days to more than two years at room temperature (25°C) in an ostrich blood vessel model developed to test post-mortem ‘tissue fixation’ by cross-linking or peroxidation. HB-induced solution hypoxia coupled with iron chelation enhances preservation as follows: HB + O 2 > HB − O 2 > −O 2 ≫ +O 2 . The well-known O 2 /haeme interactions in the chemistry of life, such as respiration and bioenergetics, are complemented by O 2 /haeme interactions in the preservation of fossil soft tissues.

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High-Pressure, High-Temperature Synthesis of Superhard Boron Suboxide

MRS Proceedings ◽

10.1557/proc-410-191 ◽

1995 ◽

Vol 410 ◽

Cited By ~ 8

Author(s):

H. Hubert ◽

L. A. J. Garvie ◽

K. Leinenweber ◽

P. R. Buseck ◽

W. T. Petuskeyt ◽

...

Keyword(s):

Pressure Range ◽

X Ray Diffraction ◽

Temperature Synthesis ◽

X Ray ◽

High Temperature Synthesis ◽

Transmission Electron ◽

High Pressure High Temperature ◽

Boron Suboxide ◽

Electron Energy Loss ◽

Rhombohedral Boron

ABSTRACTA multianvil device was used to investigate the formation of BxO phases produced in the 2 to 10 GPa pressure range with temperatures between 1000 and 1800 °C.Amorphous and crystalline B and BP were oxidized using B2O3 and CrO3. Using powder X-ray diffraction and parallel electron energy-loss spectroscopy (PEELS), we were unable to detect graphitic or diamondstructured B2O, reported in previous studies. The refractory boride B6O, which has the α-rhombohedral boron structure, is the dominant suboxide in the P and T range of our investigation. PEELS with a transmission electron microscope was used to characterize the boron oxides.

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Fabrication of boron carbonitride (BCN) nanotubes and giant fullerene cages

Canadian Journal of Chemistry ◽

10.1139/v10-146 ◽

2010 ◽

Vol 88 (12) ◽

pp. 1256-1261 ◽

Cited By ~ 4

Author(s):

Guifang Sun ◽

Faming Gao ◽

Li Hou

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

The Novel ◽

X Ray Diffraction ◽

Boron Carbonitride ◽

X Ray ◽

Transmission Electron ◽

New Form ◽

First Time ◽

Electron Energy Loss

Boron carbonitride (BCN) nanotubes have been successfully prepared using NH4Cl, KBH4, and ZnBr2 as the reactants at 480 °C for 12 h by a new benzene-thermal approach in a N2 atmosphere. As its by-product, a new form of carbon regular hexagonal nanocages are observed. The samples are characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), transmission electron diffraction (TED), electron energy loss spectroscopy (EELS), and high-resolution transmission electron microscopy (HRTEM). The prepared nanotubes have uniform outer diameters in the range of 150 to 500 nm and a length of up to several micrometerss. The novel carbon hexagonal nanocages have a typical size ranging from 100 nm to 1.5 µm, which could be the giant fullerene cages of [Formula: see text] (N = 17∼148). So, high fullerenes are observed for the first time. The influences of reaction temperature and ZnBr2 on products and the formation mechanism of BCN nanotubes are discussed.

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Above Room-Temperature Ferromagnetism in GaN Powders by Calcinations with CuO

MRS Proceedings ◽

10.1557/proc-0941-q08-14 ◽

2006 ◽

Vol 941 ◽

Cited By ~ 1

Author(s):

Lori Noice ◽

Bjoern Seipel ◽

Rolf Erni ◽

Amita Gupta ◽

Chunfei Li ◽

...

Keyword(s):

Copper Oxide ◽

Room Temperature Ferromagnetism ◽

Scanning Probe ◽

Electronic Effects ◽

X Ray Diffraction ◽

X Ray ◽

Transmission Electron ◽

Oxide Phases ◽

Probe Transmission ◽

Electron Energy Loss

ABSTRACTGallium nitride powders were calcined with copper oxide in either air or N2 and analyzed by means of powder X-ray diffraction (XRD), high-resolution parallel illumination (HRTEM) and scanning probe transmission electron microscopy (STEM), energy dispersive X-ray spectroscopy (EDXS), and electron energy loss spectroscopy (EELS) in order to address the structural and electronic effects of Cu-incorporation into GaN. Gallium oxide and multiple copper oxide phases corresponding to the calcination environment were detected. Significant changes in the lattice parameters and electronic structure of the N2-processed GaN indicate incorporation of both copper and oxygen into the GaN lattice as well as changes in the chemical bonding due to the calcinations process. SQUID magnetometer measurements at 300 K demonstrated ferromagnetism in selected samples.

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The Influences of Magnesium upon Calcium Phosphate Mineral Formation and Structure as Monitored by X-ray and Vibrational Spectroscopy

Soil Systems ◽

10.3390/soilsystems4010008 ◽

2020 ◽

Vol 4 (1) ◽

pp. 8

Author(s):

David M. Hilger ◽

Jordan G. Hamilton ◽

Derek Peak

Keyword(s):

Calcium Phosphate ◽

Calcareous Soils ◽

X Ray Diffraction ◽

Edge Structure ◽

X Ray ◽

Transmission Electron ◽

Phosphate Mineral ◽

Local Bonding ◽

Wide Range ◽

High Concentrations

Calcium phosphate minerals are typically the solubility-limiting phase for phosphate in calcareous soils. Magnesium (Mg), despite being present in high concentrations in calcareous soils, has been largely neglected in the study of formation and stabilization of soil phosphate minerals due to the high solubility of pure Mg phosphate phases. In this study, a series of four common calcium and magnesium phosphate minerals, hydroxyapatite/bobierrite and brushite/newberyite were synthesized in the presence of widely varying Mg concentrations to examine the effects of Mg substitution upon the local bonding environment and overall structure of the precipitates. Phosphorus K-edge X-Ray absorption near edge structure (XANES) and attenuated total reflectance Fourier transform infrared (ATR-FTIR) provide insight into the local coordination environment, whereas synchrotron powder X-Ray diffraction (SP-XRD) and transmission electron microscopy (TEM) were used for structural analysis. In acidic to neutral pH, Mg-bearing brushite phases formed over a wide range of Ca:Mg ratios. In neutral to high pH systems, a short-range order amorphous calcium phosphate (ACP) with a local structure analogous with hydroxyapatite precipitated for a wide range of Ca to Mg ratios. It can be inferred that the presence of Mg in soils leads to stabilization of metastable phases: via cation substitution in brushite and via poisoning of crystal growth propagation for hydroxyapatite.

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New Insight on the Hydrogen Absorption Evolution of the Mg–Fe–H System under Equilibrium Conditions

Metals ◽

10.3390/met8110967 ◽

2018 ◽

Vol 8 (11) ◽

pp. 967 ◽

Cited By ~ 8

Author(s):

Julián Puszkiel ◽

M. Castro Riglos ◽

José Ramallo-López ◽

Martin Mizrahi ◽

Thomas Gemming ◽

...

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Formation Mechanism ◽

X Ray Diffraction ◽

Equilibrium Conditions ◽

Edge Structure ◽

X Ray ◽

Solid Diffusion ◽

Transmission Electron ◽

Scanning Transmission

Mg2FeH6 is regarded as potential hydrogen and thermochemical storage medium due to its high volumetric hydrogen (150 kg/m3) and energy (0.49 kWh/L) densities. In this work, the mechanism of formation of Mg2FeH6 under equilibrium conditions is thoroughly investigated applying volumetric measurements, X-ray diffraction (XRD), X-ray absorption near edge structure (XANES), and the combination of scanning transmission electron microscopy (STEM) with energy-dispersive X-ray spectroscopy (EDS) and high-resolution transmission electron microscopy (HR-TEM). Starting from a 2Mg:Fe stoichiometric powder ratio, thorough characterizations of samples taken at different states upon hydrogenation under equilibrium conditions confirm that the formation mechanism of Mg2FeH6 occurs from elemental Mg and Fe by columnar nucleation of the complex hydride at boundaries of the Fe seeds. The formation of MgH2 is enhanced by the presence of Fe. However, MgH2 does not take part as intermediate for the formation of Mg2FeH6 and acts as solid-solid diffusion barrier which hinders the complete formation of Mg2FeH6. This work provides novel insight about the formation mechanism of Mg2FeH6.

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A study on the growth and structure of titania nanotubes

Journal of Materials Research ◽

10.1557/jmr.2004.19.2.417 ◽

2004 ◽

Vol 19 (2) ◽

pp. 417-422 ◽

Cited By ~ 147

Author(s):

Wenzhong Wang ◽

Oomman K. Varghese ◽

Maggie Paulose ◽

Craig A. Grimes ◽

Qinglei Wang ◽

...

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Chemical Process ◽

Alkali Treatment ◽

Titania Nanotubes ◽

X Ray Diffraction ◽

X Ray ◽

Transmission Electron ◽

Spectroscopy Studies ◽

Electron Energy Loss

Titania nanotubes synthesized by a soft chemical process are described, having diameters of 8 nm to 10 nm and lengths ranging from approximately 0.1 μm to 1 μm. X-ray diffraction studies show the structure of the as-prepared nanotubes is the same as that of the starting anatase TiO2nanoparticles. Energy-dispersive x-ray analysis and electron energy loss spectroscopy studies further indicate that the as-prepared nanotubes are composed of titania. Studies using transmission electron microscopy verified that the nanotubes are formed during alkali treatment, with subsequent acidic treatments having no effect on nanotube structure and shape.

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Investigations on electronic structure of YMnO3 by electron energy loss spectra and first-principle calculations

Powder Diffraction ◽

10.1017/s0885715619000617 ◽

2019 ◽

Vol 34 (4) ◽

pp. 339-344

Author(s):

S. Wang ◽

J. Cai ◽

H. D. Xu ◽

H. L. Tao ◽

Y. Cui ◽

...

Keyword(s):

Electronic Structure ◽

Energy Loss ◽

Experimental Spectrum ◽

X Ray Diffraction ◽

Edge Structure ◽

Transmission Electron ◽

The Individual ◽

Electron Energy Loss ◽

Electron Energy Loss Spectra ◽

Good Agreement

Crystal structure and electronic structure of YMnO3 were investigated by X-ray diffraction and transmission electron microscopy related techniques. According to the density of states (DOS), the individual interband transitions to energy loss peaks in the low energy loss spectrum were assigned. The hybridization of O 2p with Mn 3d and Y 4d analyzed by the partial DOS was critical to the ferroelectric nature of YMnO3. From the simulation of the energy loss near-edge structure, the fine structure of O K-edge was in good agreement with the experimental spectrum. The valence state of Mn (+3) in YMnO3 was determined by a comparison between experiment and calculations.

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Nanostructure of a Glass-Like Carbon Characterized by X-Ray Diffraction and Electron Energy Loss Spectroscopy

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.177.58 ◽

2010 ◽

Vol 177 ◽

pp. 58-61 ◽

Cited By ~ 1

Author(s):

Zhi Li Zhang ◽

Rik Brydson ◽

Aidan Westwood ◽

B. Rand

Keyword(s):

Energy Loss ◽

Electron Energy ◽

Treatment Temperature ◽

X Ray Diffraction ◽

Phenolic Resins ◽

X Ray ◽

Transmission Electron ◽

Different Temperatures ◽

Electron Energy Loss ◽

Crystalline Graphite

In our present study, phenolic resins heated at different temperatures from 600 oC to 3000 oC were analysised in terms of phase structure and chemical structure using X-ray diffraction and high resolution transmission electron microscopy equipped with an electron energy loss spectrometer (EELS). It is shown that materials appear to be amorphous with many micro-pores surrounded by crystalline graphite layers; the formation of the pore is due to the gas evolution reaction. Using the intensities of peaks in EELS CK-ionization edge which arise from transition of an atomic 1s electron to the π* and σ* antibonding band-like states, the percentage of sp2-bonded carbon have been analyzed and the results reveal notable differences with heat treatment temperature.

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Sodium-Vanadium Bronze Na9V14O35: An Electrode Material for Na-Ion Batteries

Molecules ◽

10.3390/molecules27010086 ◽

2021 ◽

Vol 27 (1) ◽

pp. 86

Author(s):

Maria A. Kirsanova ◽

Alexey S. Akmaev ◽

Mikhail V. Gorbunov ◽

Daria Mikhailova ◽

Artem M. Abakumov

Keyword(s):

Negative Electrode ◽

X Ray Diffraction ◽

Conversion Reaction ◽

X Ray ◽

Electroactive Material ◽

Transmission Electron ◽

Scanning Transmission ◽

Electrochemical Capacity ◽

Silica Ampoule ◽

Electron Energy Loss

Na9V14O35 (η-NaxV2O5) has been synthesized via solid-state reaction in an evacuated sealed silica ampoule and tested as electroactive material for Na-ion batteries. According to powder X-ray diffraction, electron diffraction and atomic resolution scanning transmission electron microscopy, Na9V14O35 adopts a monoclinic structure consisting of layers of corner- and edge-sharing VO5 tetragonal pyramids and VO4 tetrahedra with Na cations positioned between the layers, and can be considered as sodium vanadium(IV,V) oxovanadate Na9V104.1+O19(V5+O4)4. Behavior of Na9V14O35 as a positive and negative electrode in Na half-cells was investigated by galvanostatic cycling against metallic Na, synchrotron powder X-ray diffraction and electron energy loss spectroscopy. Being charged to 4.6 V vs. Na+/Na, almost 3 Na can be extracted per Na9V14O35 formula, resulting in electrochemical capacity of ~60 mAh g−1. Upon discharge below 1 V, Na9V14O35 uptakes sodium up to Na:V = 1:1 ratio that is accompanied by drastic elongation of the separation between the layers of the VO4 tetrahedra and VO5 tetragonal pyramids and volume increase of about 31%. Below 0.25 V, the ordered layered Na9V14O35 structure transforms into a rock-salt type disordered structure and ultimately into amorphous products of a conversion reaction at 0.1 V. The discharge capacity of 490 mAh g−1 delivered at first cycle due to the conversion reaction fades with the number of charge-discharge cycles.

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Superhard B–C–N materials synthesized in nanostructured bulks

Journal of Materials Research ◽

10.1557/jmr.2002.0454 ◽

2002 ◽

Vol 17 (12) ◽

pp. 3139-3145 ◽

Cited By ~ 169

Author(s):

Y. Zhao ◽

D. W. He ◽

L. L. Daemen ◽

T. D. Shen ◽

R. B. Schwarz ◽

...

Keyword(s):

High Pressure ◽

Indentation Hardness ◽

X Ray Diffraction ◽

X Ray ◽

Amorphous Phases ◽

Transmission Electron ◽

Pressure Synthesis ◽

Nanocrystalline Composite ◽

Electron Energy Loss ◽

Electron Energy Loss Spectra

We report here the high-pressure synthesis of well-sintered millimeter-sized bulks of superhard BC2N and BC4N materials in the form of a nanocrystalline composite with diamond-like amorphous carbon grain boundaries. The nanostructured superhard B–C–N material bulks were synthesized under high P–T conditions from amorphous phases of the ball-milled molar mixtures. The synthetic B–C–N samples were characterized by synchrotron x-ray diffraction, high-resolution transmission electron microscope, electron energy-loss spectra, and indentation hardness measurements. These new high-pressure phases of B–C–N compound have extreme hardnesses, second only to diamond. Comparative studies of the high P–T synthetic products of BC2N, BC4N, and segregated phases of diamond + cBN composite confirm the existence of the single B–C–N ternary phases.

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