Nature Milestones in Crystallography, a collaborative effort between Nature, Nature Materials, Nature Nanotechnology and Nature Structural & Molecular Biology, is the eleventh supplement in the series and is timed to coincide with the celebration of the 2014 International Year of Crystallography. Exactly 100 years ago, Max von Laue received the Nobel Prize in Physics “for his discovery of the diffraction of X-rays by crystals”. Since that discovery, crystallography has become an essential tool of investigation throughout the sciences, largely because it provides conclusive information on molecular structure down to the atomic level.
Scientists used the ChemCam instrument on NASA's Curiosity Mars rover to examine a Martian rock "shell" about one inch across, embedded in bedrock and with a hollow interior. This graphic combines an image of the target with results from using ChemCam's laser on the rock and adjacent points
Recent developments in shock-free dynamic (ramp) compression now allow laboratory access to this dense matter regime. Here we describe ramp-compression measurements for diamond, achieving 3.7-fold compression at a peak pressure of 5 terapascals (equivalent to 50 million atmospheres). These equation-of-state data can now be compared to first-principles density functionalcalculations and theories long used to describe matter present in the interiors of giant planets, in stars, and in inertial-confinement fusion experiments. Our data also provide new constraints on mass–radius relationships for carbon-rich planets.
The Earth Sciences Division (ESD) at Berkeley Lab brings together geoscientists, mathematicians, microbiologists, computer scientists and engineers to address local, national and global problems related to energy resources, environmental...
Researchers of Chapman University, the U.S. Geological Survey and SSRL have investigated the speciation of arsenic changes within mine tailings and surrounding soil samples. The scientists identified arsenic-containing mineral and sorbed species in size-fractionated mine wastes and adjacent soils from the Solomon Mine and the Descarga Tailings Dam in the Randsburg Historic Mining District, California, using extended x-ray absorption fine structure (EXAFS) spectroscopy at SSRL’s Beam Line 11-2. These analyses were paired with micro-x-ray fluorescence (μXRF) mapping of separate size fractions to identify multiple populations of particles with different arsenic-to-iron ratios.
Easily separable humic acid coated magnetite (HA-Fe3O4) nanoparticles are employed for effective adsorption and reduction of toxic Cr(VI) to nontoxic Cr(III). The adsorption and reduction of Cr(VI) is effective under acidic, neutral, and basic pH conditions.
Experimental data reveal that mineral precipitation takes place directly on free viruses and, as a result of viral infections, on cell debris resulting from cell lysis. Viruses are initially permineralized by amorphous magnesium silicates, which then alter to magnesium carbonate nanospheres of ~80–200 nm in diameter during diagenesis.
Astrobiologists hope that the detection of certain minerals on exoplanets by ever-more-sensitive space telescopes could indicate biochemical processes associated with life (#Minerology of #NewfoundPlanet could point to habitability.
This is a review of the elastic behaviour and pressure (P)-induced structural evolution of zeolites and presents a comparative analysis of the deformation mechanisms of the Si/Al-framework and the rearrangement of the extra-framework species in response to applied pressure.
The authors demonstrate that recording XANES spectra of calcium carbonate at the oxygen K-edge enables polarization-dependent imaging contrast (PIC) mapping with unprecedented contrast, signal-to-noise ratio, and magnification. O and Ca spectra are presented for six calcium carbonate minerals: aragonite, calcite, vaterite, monohydrocalcite, and both hydrated and anhydrous amorphous calcium carbonate.
Higher Cr(VI) values are observed in aquifers in alluvial and neogene sediments of serpentine and amphibolite, originating from the erosion of ophiolithic and metamorphic rocks. In contrast, Cr(VI) concentration in samples from ophiolithic and metamorphic rocks was always below 10 μg/L due to both low contact time and surface area, as verified by low conductivity and salt concentration values. These findings indicate that under specific conditions, pollution of water by Cr(VI) is favorable by a slow MnO2-catalyzed oxidation of soluble Cr(III) to Cr(VI) in which manganese products [Mn(III)/Mn(II)] are probably re-oxidized by oxygen.
University of Nottingham-British Geological Survey Centre for Environmental Geochemistry (RT @MelJLeng: Some new blogs from the @BritGeoSurvey @UniofNottingham Centre for Environmental Geochemistry http://t.co/lvRr955181)...
The authors present a high-resolution transect of dissolved stable iron isotope ratios (δ56Fe) and iron concentrations ([Fe]) along a section of the North Atlantic Ocean. The different iron sources can be identified by their unique δ56Fe signatures, which persist throughout the water column. This allowed to calculate the relative contribution from dust, hydrothermal venting and reductive and non-reductive sedimentary release to the dissolved phase. They found that Saharan dust aerosol is the dominant source of dissolved iron along the section, contributing 71–87 per cent of dissolved iron.
The results demonstrate an instrumental bias associated with APT that needs to be quantified and corrected to obtain accurate isotope ratios. After this correction is applied, this technique should allow determination of the distribution of 12C/13C ratios in individual diamond grains, solving the decades-old question of the origin of meteoritic nanodiamonds.
One of Europe's premier scientific research laboratories is to go through a major upgrade. The improvements to the European Synchrotron Radiation Facility (ESRF) will cost some 150m euros (£120m) and take until 2022 to complete fully. The 850m accelerator ring used to prime these bright X-rays will be replaced.
Ancient sulfide-bearing cumulates would be characterized by unradiogenic Pb and He isotopes (high-3He/4He). These primitive signatures are usually attributed to primordial, undifferentiated mantle, but in this case, they are the very imprint of mantle differentiation via continent formation.
Iceland has been considered a suitable analogue for the generation of Earth’s earliest continental crust. However, the geochemical signature of sialic rocks from Iceland is distinct from the typical 3.9- to 2.5-billion-year-old Archaean rocks discovered so far. Here the authors report the discovery of an exceptionally well-preserved, 4.02-billion-year-old tonalitic gneiss rock unit within the Acasta Gneiss Complex in Canada.
The Deep Carbon Observatory is a global community of multi-disciplinary scientists unlocking the inner secrets of Earth through investigations into life, life, energy, and the fundamentally unique chemistry of carbon.
The authors briefly recount the extraordinary story of the search and discovery of the first natural quasicrystal. Since 1984, >100 different types of quasicrystals have been synthesized in the laboratory under carefully controlled conditions. The original theory suggested that quasicrystals can be as robust and stable as crystals, perhaps even forming under natural conditions. This thought motivated a decade-long search for a natural quasicrystal, culminating in the discovery of icosahedrite (Al63Cu24Fe13), an icosahedral quasicrystal found in a museum sample consisting of several typical rock-forming minerals combined with exotic rare metal alloy minerals like khatyrkite and cupalite.
urrently, calcium L-edge X-ray absorption near-edge structure (XANES) spectra are used to distinguish between different calcium carbonate polymorphs, including calcite and aragonite, while oxygen and carbon K-edge XANES spectra are often used to determine the c axis orientation of a given calcium carbonate crystal.