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We present results from high-pressure, high-temperature experiments that generate incipient carbonate melts at mantle conditions (~90 kilometers depth and temperatures between 750° and 1050°C). We show that these primitive carbonate melts can sequester sulfur in its oxidized form of sulfate, as well as base and precious metals from mantle lithologies of peridotite and pyroxenite. It is proposed that these carbonate sulfur-rich melts may be more widespread than previously thought and that they may play a first-order role in the metallogenic enhancement of localized lithospheric domains. They act as effective agents to dissolve, redistribute, and concentrate metals within discrete domains of the mantle and into shallower regions within Earth, where dynamic physicochemical processes can lead to ore genesis at various crustal depths. [ABSTRACT FROM AUTHOR]

The ∼3430 Ma Strelley Pool Formation (SPF), Pilbara, Western Australia contains some of the most diverse microfossil evidence for early life on Earth. Here we report an assemblage of tephra (scoria, tubular pumice, plus vesicular and non-vesicular volcanic glass shards) from two stratigraphic levels in the SPF, including morphotypes that closely resemble previously described microfossils from this unit and elsewhere. Clasts of scoria are characterised by numerous spheroidal vesicles, with subordinate eye- and lens-shaped morphotypes, commonly lined with anatase (TiO 2 ) and small amounts of organic material. Their diameters range from 5–180 μm with 80% in the 10–50 μm range. Fragments of tubular pumice are also lined with anatase + / − carbon and have tube diameters of 5–15 μm. Other volcanic ejecta particles include a multitude of sub-angular shard particles with or without vesicles, plus more rounded vase-shaped, eye-shaped, and hair-like morphologies; once again, most of these are coated by anatase + / − carbon and are several tens of micrometres in size. Many of the tephra fragments are now entirely silicified with no compositional difference between the former volcanic glass, the vesicle infill and the clast matrix. However, some examples retain a partial aluminosilicate composition, either as a vesicle infilling phase or as isolated lath-like grains within the formerly glassy groundmass. Isolated occurrences of some of these tephra morphotypes strongly resemble simple microbial morphologies including pairs and clusters of cells (cf. scoria), filamentous microbes (cf. tubular pumice) and larger sheaths/cysts (cf. sub-rounded glass shards). Furthermore, some tephra-containing clasts occur in a SPF sandstone unit that hosts previously described microfossils, while others are interbedded with chert layers from which microfossils have also been described. In light of our new volcanogenic data, we evaluate the robustness of previous microfossil evidence from the SPF in the East Strelley greenstone belt. We find that the majority of previously illustrated microfossils from this greenstone belt possess multiple features that are consistent with a biological interpretation and are unlikely to be volcanogenic, but at least one previously illustrated specimen is here reinterpreted as volcanic in origin. The importance of this work is that it serves to highlight the common occurrence of volcanogenic microstructures resembling biological fossils (i.e. pseudo-fossils) in Archean environments that are habitable for life. Such structures have until now been largely overlooked in the assessment of putative Precambrian microfossils. Our data show that tephra-derived microstructures should be considered as a null hypothesis in future evaluations of potential signs of life on the early Earth, or on other planets. [ABSTRACT FROM AUTHOR]

Organic-walled microfossils provide the best insights into the composition and evolution of the biosphere through the first 80 percent of Earth history. The mechanism of microfossil preservation affects the quality of biological information retained and informs understanding of early Earth palaeo-environments. We here show that 1 billion-year-old microfossils from the non-marine Torridon Group are remarkably preserved by a combination of clay minerals and phosphate, with clay minerals providing the highest fidelity of preservation. Fe-rich clay mostly occurs in narrow zones in contact with cellular material and is interpreted as an early microbially-mediated phase enclosing and replacing the most labile biological material. K-rich clay occurs within and exterior to cell envelopes, forming where the supply of Fe had been exhausted. Clay minerals inter-finger with calcium phosphate that co-precipitated with the clays in the sub-oxic zone of the lake sediments. This type of preservation was favoured in sulfate-poor environments where Fe-silicate precipitation could outcompete Fe-sulfide formation. This work shows that clay minerals can provide an exceptionally high fidelity of microfossil preservation and extends the known geological range of this fossilization style by almost 500 Ma. It also suggests that the best-preserved microfossils of this time may be found in low-sulfate environments. [ABSTRACT FROM AUTHOR]

Highlights: [•] We examined 3.25Ga pyritic filamentous objects at the nano-scale. [•] The filaments contain potential chemical, morphological and textural biosignals. [•] Bona fide pyritised microfossils from the Gunflint chert exhibit similar biosignals. [•] Isotopic data are consistent with a hydrothermal vent setting for the filaments. [•] The data are consistent with a biological formation mechanism but not compelling. [ABSTRACT FROM AUTHOR]

Abstract: Published toxicology data on chitosan nanoparticles (NP) often lack direct correlation to the in situ size and surface characteristics of the nanoparticles, and the repeated NP assaults as experienced in chronic use. The aim of this paper was to breach these gaps. Chitosan nanoparticles synthesized by spinning disc processing were characterised for size and zeta potential in HBSS and EMEM at pHs 6.0 and 7.4. Cytotoxicity against the Caco-2 cells was evaluated by measuring the changes in intracellular mitochondrial dehydrogenase activity, TEER and sodium fluorescein transport data and cell morphology. Cellular uptake of NP was observed under the confocal microscope. Contrary to established norms, the collective data suggest that the in vitro cytotoxicity of NP against the Caco-2 cells was less influenced by positive surface charges than by the particle size. Particle size was in turn determined by the pH of the medium in which the NP was dispersed, with the mean size ranging from 25 to 333nm. At exposure concentration of 0.1%, NP of 25±7nm (zeta potential 5.3±2.8mV) was internalised by the Caco-2 cells, and the particles were observed to inflict extensive damage to the intracellular organelles. Concurrently, the transport of materials along the paracellular pathway was significantly facilitated. The Caco-2 cells were, however, capable of recovering from such assaults 5days following NP removal, although a repeat NP exposure was observed to produce similar effects to the 1st exposure, with the cells exhibiting comparable resiliency to the 2nd assault. [Copyright &y& Elsevier]

In this study, solid state chemical reaction of anhydrous chloride precursors with NaCO has been used to manufacture composite powders of nanocrystalline rare earth oxide grains embedded within a matrix of NaCl. Subsequent washing of these powders with deionised water resulted in removal of the NaCl matrix and hydration of the oxide nanoparticles. In the case of NdO and SmO, the hydration process yielded hydroxide nanorods. In contrast, washing of the GdO yielded a powder consisting of irregularly shaped nanoparticles of GdO and GdOOH. Analysis using high resolution transmission electron microscopy revealed that the NdO and SmO nanorods were not single crystals but were composed of crystalline subunits with a common $$ \left\langle {0001} \right\rangle $$ growth direction. The results obtained in this study demonstrate that rare earth hydroxide nanorods can be synthesised from oxide precursors without the need for hydrothermal processing at elevated temperature and pressure. [ABSTRACT FROM AUTHOR]

Abstract: Pyrite (FeS2) oxidation in modern sedimentary environments is neither a purely chemical nor purely microbial process, but it is significantly enhanced by the activity of microorganisms that use reduced forms of iron and sulphur in their metabolisms. On the early Earth, where oxygen levels were thought to be <10−5 of the present atmospheric level and chemical oxidants scarce, such biological mediation may have been critical in the redox cycles of iron and sulphur. Here, we show that detrital sedimentary pyrite grains in a ~3.4 billion-year-old sandstone were colonised by microbial communities. The detrital pyrite comes from the basal quartz arenite member of the 3.43–3.35Ga Strelley Pool Formation (SPF) in the East Strelley greenstone belt of the Pilbara Craton, Western Australia. Rock chips and petrographic thin sections of black sandstones occurring on two ridges close to the SPF type locality of Strelley Pool were investigated using optical microscopy, SEM, TEM, laser Raman and NanoSIMS. The detrital pyrite grains exhibit laminated carbonaceous coatings of early Archean age, with localised enrichments of nitrogen that are interpreted as the in situ remains of biofilms growing on these nutrient-rich minerals. Pyrite surfaces contain spherical pits, chains of pits and channels that are morphologically distinct from abiotic alteration features. The pits and channels are widespread, have a clustered distribution typical of microbial colonisation, and are closely comparable to biologically mediated microstructures in the younger rock record and those created by extant Fe- and S-oxidising microbes in the laboratory. They are thus interpreted as trace fossils formed by the attachment of bacteria to the pyrite surfaces. A nano-layer and discreet nano-grains of secondary mineral precipitates, namely Fe-oxides belonging to the magnetite-maghaemite group, attest to pyrite oxidation. These are intimately associated with the biofilms and trace fossils, and are interpreted to represent the fossilised mineral products of biologically mediated pyrite oxidation. These data extend the geological range of microbes capable of metabolising reduced Fe and/or S compounds back to the early Archean and indicate that pyrite-rich sedimentary rocks provide promising targets in the search for extraterrestrial life. [Copyright &y& Elsevier]

Despite its broad applicability NMR has always been limited by its inherently low sensitivity. Hyperpolarization methods have the potential to overcome this limitation and, in the case of ex situ dynamic nuclear polarization (DNP), large enhancement factors have been achieved. Although many other polarization methods have been described in the past, including chemically and parahydrogen-induced polarization and optical pumping, DNP has recently been the most popular. Here we present an additional polarization mechanism arising from quantum rotor effects in methyl groups, which generates polarizations at temperatures <1.5 K and interferes with DNP at such temperatures. The polarization generated by this mechanism is efficiently transferred via carbon bound protons. Although quantum rotor polarizations have been studied for a small range of molecules in great detail, we observe such effects for a much broader range of substances with very different polarization rates at temperatures <1.5 K. Moreover, we report transfer of quantum rotor polarization across a chain of protons. The observed effect not only influences the polarization in low-temperature DNP experiments but also opens a new independent avenue to generate enhanced sensitivity for NMR. [ABSTRACT FROM AUTHOR]

Two narrow-channel reactor designs have been developed and used in conjunction with gas–liquid segmented flow in order to intensify reactions and to effect synthesis under continuous flow conditions, incorporating single pass and recirculating capability, under high pressure and temperature. Silver nanoparticles approximately 3–5 nm in diameter are accessible with the average size depending on the reaction temperature and polyphosphate concentration, with smaller and more monodisperse nanoparticles produced at low polyphosphate concentrations and low temperatures. The use of continuous flow conditions leads to the possibility of simple scale-up to commercial production. [ABSTRACT FROM AUTHOR]

Two narrow-channel reactor designs have been developed and used in conjunction with gas–liquid segmented flow in order to intensify reactions and to effect synthesis under continuous flow conditions, incorporating single pass and recirculating capability, under high pressure and temperature. Silver nanoparticles approximately 3–5 nm in diameter are accessible with the average size depending on the reaction temperature and polyphosphate concentration, with smaller and more monodisperse nanoparticles produced at low polyphosphate concentrations and low temperatures. The use of continuous flow conditions leads to the possibility of simple scale-up to commercial production. [ABSTRACT FROM AUTHOR]

Abstract: Understanding biomineralization processes provides a route to the formation of novel biomimetic materials with potential applications in fields from medicine to materials engineering. The teeth of chitons (marine molluscs) represent an excellent example of a composite biomineralized structure, comprising variable layers of iron oxide, iron oxyhydroxide and apatite. Previous studies of fully mineralized teeth using X-ray diffraction, Raman spectroscopy and scanning electron microscopy (SEM) have hinted at the underlying microstructure, but have lacked the resolution to provide vital information on fine scale structure, particularly at interfaces. While transmission electron microscopy (TEM) is capable of providing this information, difficulties in producing suitable samples from the hard, complex biocomposite have hindered progress. To overcome this problem we have used focused ion beam (FIB) processing to prepare precisely oriented sections across interfaces in fully mineralized teeth. In particular, the composite structure is found to be more complex than previously reported, with additional phases (goethite and amorphous apatite) and interface detail observed. This combination of FIB processing and TEM analysis has enabled us to investigate the structural and compositional properties of this complex biocomposite at higher resolution than previously reported and has the potential to significantly enhance future studies of biomineralization in these animals. [Copyright &y& Elsevier]

The symbiosis between cnidarians and dinoflagellate algae is not understood at the cell or molecular level, yet this relationship is responsible for the formation of thousands of square kilometres of coral reefs. We have investigated the nature of crystalline material prominent within marine algal symbionts of Aiptasia sp. anemones. This material, which has historically been considered to be calcium oxalate, is shown to be uric acid. We demonstrate that these abundant uric acid stores can be mobilized rapidly, thereby allowing the algal symbionts to flourish in an otherwise N-poor environment. This is the first report of uric acid accumulation by symbiotic marine algae. These data provide new insight and considerations for understanding the physiological basis of algal symbioses, and represent a new and previously unconsidered aspect of N metabolism in cnidarian, and a variety of other, marine symbioses. [ABSTRACT FROM AUTHOR]

This paper reports on a unique crystallization phenomenon of amorphous plasma-enhanced chemical vapour deposited SiN x thin films induced by heating to temperatures ⩾1148K in air. The crystallization occurs as randomly scattered pits, within which clusters of smaller crystals form. The crystals formed are free of oxygen and are identified to be α-Si3N4. The crystallization is associated with a large volume contraction, which results in internal cracking. [Copyright &y& Elsevier]

The equilibrium isotope effect (EIE) for the interconversion of the two chair isotopomers of 1-trideutero-1,3,3-trimethylcyclohexane was predicted using geometry and vibrational force constants derived from electronic structure theory at HF, B3LYP, and MP2 levels as input for the program THERMISTP. Agreement between theory and previously reported NMR results is very good (experimental Keq = 1.042 ± 0.001 vs Keq = 1.0409 at MP216-311G* level, Keq = 1.0503 at HF/6-311 G*, and Keg = 1.0417 at B3LYP/6-311G* level, all at 17 °C). In order to investigate the origin of this isotope effect, the calculated EIEs for the monodeuterated isotopomers were analyzed. It has been shown that the hydrogen atom on an axial methyl group which is unusually close to its counterpart on the other axial methyl is responsible for the large (steric) isotope effect in the compound studied. [ABSTRACT FROM AUTHOR]

Fullerenes were pyrolyzed by subliming them into a stream of flowing argon gas and then passing them through an oven heated to &tild;1000 °C. C76, C78, and C84 all readily lost carbons to form smaller fullerenes. In the case of C78, some isomerization was seen. Pyrolysis of 3He@C76 showed that all or most of the 3He was lost during the decomposition. C60 passes through the apparatus with no decomposition and no loss of helium. [ABSTRACT FROM AUTHOR]

Three plausible routes for the five-membered ring expansion in the equilibrating 2-cyclopentyl-2propyl and 1-(2-propyl)cyclopentyl cations 1A/1B were located on the PES, all calculated at the MP4/6-31G(d)//MP2/6-31G(d) level of theory. In pathway I, the six-membered transition structure (TS-I) connects the less stable cyclopentyl cation 1A and the 1,2-dimethylcyclohexyl carbocation (2) via a barrier of 16.4 kcal/mol. In pathway II, which has a barrier of 16.3 kcal/mol, the methyl migration occurs first in the more stable 1B via transition structure TS-II. Pathway III involves the uphill hydride shift and formation of the secondary cation 3, which undergoes WagnerMeerwein 1,2-isopropyl shift via a transition structure TS-III and the protonated carbocation intermediate 4. The barrier pathway III is for 17.0 kcal/mol. Experimental secondary deuterium isotope effects of the rearrangement were measured for the hexadeuterated 1A-d[sub 6]/1B-d[sub 6] (k[sub H]/k[sub D]) = 2.40) and tetradeuterated 1A-d[sub 4]/1B-d[sub 4] (k[sub H]/k[sub D]) = 0.18) cations by means of ¹H NMR. Comparison of the experimental data with the theoretical values (k[sub H]/k[sub D] = 2.40 for 1B-d[sub 6] and k[sub H]/k[sub D]) = 0.24 for 1B-d[sub 4], respectively) obtained with QUIVER revealed that pathway II is a major reaction route. [ABSTRACT FROM AUTHOR]

Presents study on the equilibria of reversible Diels-Alder addition to fullerenes using [sup 3]He nuclear magnetic resonance (NMR) spectroscopy. Reactions of fullerenes with dimethyl anthracene (DMA); Existence of isomers in the reaction mixtures; Independence of NMR intensities to DMA concentration.

Background and aims: An overlooked fraction of the terrestrial carbon (C) pool is that associated with biogenic silica deposited in plants (phytoliths), so-called PhytOC. This fraction is small compared with the main C pools, but is of interest because it could be a long-term C sink as phytoliths may protect organic C from mineralization. However, the topic is hotly contested and unclear due to both methodological and theoretical limitations.We aim to review this topic, with specific emphasis on: (i) the range of C concentrations associated with phytoliths; (ii) soil phytolith preservation and subsequent organic C mineralization; and (iii) global estimates of C sequestration within PhytOC.Recent work has suggested that [PhytOC] could be much greater than currently acknowledged, but also highly variable and dependent on cell silicification types. A short case study using cryo‐Scanning Electron Microscopy (cryo-SEM), X‐ray microanalysis (EDX), plus Focused Ion Beam (FIB) and Scanning Transmission Electron Microscopy (STEM) on the culms of a sedge (Schoenus caespititius) confirmed this thinking. Understanding of both phytolith and PhytOC fates in soil is poor. We suggest that phytolith residence time should be seen as a gradient. Such a continuum is explained by different phytolith sizes, types and chemistry, which will also have contrasting PhytOC. Our estimation of C sequestration as PhytOC each year (11–190 Tg C yr−1) represents between < 1% and 13% of the C that could be sequestered globally in soils (estimated at 1400 Tg C yr−1). We conclude that (1) more research is needed to improve our understanding of the formation and fate of PhytOC in terrestrial ecosystems and (2) it would be unwise to put our faith in PhytOC sequestration or other related methodologies to “solve” the climate crisis.Scope: An overlooked fraction of the terrestrial carbon (C) pool is that associated with biogenic silica deposited in plants (phytoliths), so-called PhytOC. This fraction is small compared with the main C pools, but is of interest because it could be a long-term C sink as phytoliths may protect organic C from mineralization. However, the topic is hotly contested and unclear due to both methodological and theoretical limitations.We aim to review this topic, with specific emphasis on: (i) the range of C concentrations associated with phytoliths; (ii) soil phytolith preservation and subsequent organic C mineralization; and (iii) global estimates of C sequestration within PhytOC.Recent work has suggested that [PhytOC] could be much greater than currently acknowledged, but also highly variable and dependent on cell silicification types. A short case study using cryo‐Scanning Electron Microscopy (cryo-SEM), X‐ray microanalysis (EDX), plus Focused Ion Beam (FIB) and Scanning Transmission Electron Microscopy (STEM) on the culms of a sedge (Schoenus caespititius) confirmed this thinking. Understanding of both phytolith and PhytOC fates in soil is poor. We suggest that phytolith residence time should be seen as a gradient. Such a continuum is explained by different phytolith sizes, types and chemistry, which will also have contrasting PhytOC. Our estimation of C sequestration as PhytOC each year (11–190 Tg C yr−1) represents between < 1% and 13% of the C that could be sequestered globally in soils (estimated at 1400 Tg C yr−1). We conclude that (1) more research is needed to improve our understanding of the formation and fate of PhytOC in terrestrial ecosystems and (2) it would be unwise to put our faith in PhytOC sequestration or other related methodologies to “solve” the climate crisis.Conclusions: An overlooked fraction of the terrestrial carbon (C) pool is that associated with biogenic silica deposited in plants (phytoliths), so-called PhytOC. This fraction is small compared with the main C pools, but is of interest because it could be a long-term C sink as phytoliths may protect organic C from mineralization. However, the topic is hotly contested and unclear due to both methodological and theoretical limitations.We aim to review this topic, with specific emphasis on: (i) the range of C concentrations associated with phytoliths; (ii) soil phytolith preservation and subsequent organic C mineralization; and (iii) global estimates of C sequestration within PhytOC.Recent work has suggested that [PhytOC] could be much greater than currently acknowledged, but also highly variable and dependent on cell silicification types. A short case study using cryo‐Scanning Electron Microscopy (cryo-SEM), X‐ray microanalysis (EDX), plus Focused Ion Beam (FIB) and Scanning Transmission Electron Microscopy (STEM) on the culms of a sedge (Schoenus caespititius) confirmed this thinking. Understanding of both phytolith and PhytOC fates in soil is poor. We suggest that phytolith residence time should be seen as a gradient. Such a continuum is explained by different phytolith sizes, types and chemistry, which will also have contrasting PhytOC. Our estimation of C sequestration as PhytOC each year (11–190 Tg C yr−1) represents between < 1% and 13% of the C that could be sequestered globally in soils (estimated at 1400 Tg C yr−1). We conclude that (1) more research is needed to improve our understanding of the formation and fate of PhytOC in terrestrial ecosystems and (2) it would be unwise to put our faith in PhytOC sequestration or other related methodologies to “solve” the climate crisis. [ABSTRACT FROM AUTHOR]

Deals with a study that reported the extension of the high-performance liquid chromatography (HPLC) procedure enabling to obtain Kr@C in reasonable yield from a crude mixture. Experimental methods of the study; Analysis of the chromatogram of a mixture of C60 and Kr@C60 on the PYE [2-(1-pyrenyl)ethylsilyl] column; Results and discussion; Conclusions.

Presents data describing how fullerenes labeled with 3He are used in a reaction. How the dimer HE2's bonding energy is weak, leading to dissociation; Dissociated species being called van der Waals complexes, as contrasted with noble gas atoms inside fullerenes which are extremely stable, which could be identified as compounds; Buckminsterfullerene as a basis for a huge volume of experimental and theoretical work.

Xenolithic corundum aggregates in Cretaceous mafic pyroclastics from Mount Carmel contain pockets of silicate melts with mineral assemblages [SiC (moissanite), TiC, Ti2O3 (tistarite), Fe-Ti-Zr silicides/phosphides] indicative of magmatic temperatures and oxygen fugacity (fO2) at least 6 log units below the iron-wüstite buffer (ΔIW ≤ –6). Microstructural evidence indicates that immiscible, carbon-rich metallic (Fe-Ti-Zr-Si-P) melts separated during the crystallization of the silicate melts. The further evolution of these metallic melts was driven by the crystallization of two main ternary phases (FeTiSi and FeTiSi2) and several near-binary phases, as well as the separation of more evolved immiscible melts. Reconstructed melt compositions fall close to cotectic curves in the Fe-Ti-Si system, consistent with trapping as metallic liquids. Temperatures estimated from comparisons with experimental work range from ≥1500 °C to ca. 1150 °C; these probably are maximum values due to the solution of C, H, P, and Zr. With decreasing temperature (T), the Si, Fe, and P contents of the Fe-Ti-Si melts increased, while contents of Ti and C decreased. The increase in Si with declining T implies a corresponding decrease in fO2, probably to ca. ΔIW-9. The solubility of P in the metallic melts declined with T and fO2, leading to immiscibility between Fe-Ti-Si melts and (Ti,Zr)-(P,Si) melts. Decreasing T and fO2 also reduced the solubility of C in the liquid metal, driving the continuous crystallization of TiC and SiC during cooling. The lower-T metallic melts are richer in Cr, and to some extent V, as predicted by experimental studies showing that Cr and V become more siderophile with decreasing fO2. These observations emphasize the importance of melt-melt immiscibility for the evolution of magmas under reducing conditions. The low fO2 and the abundance of carbon in the Mt. Carmel system are consistent with a model in which differentiating melts were fluxed by fluids that were dominated by CH4+H2, probably derived from a metal-saturated sublithospheric mantle. A compilation of other occurrences suggests that these phenomena may commonly accompany several types of explosive volcanism. [ABSTRACT FROM AUTHOR]

Very small (∼2 nm) silver nanoparticles can be readily prepared using p-phosphonated calixarenes as templating agents and surfactants, at the same time allowing the use of hydrogen gas as an environmentally benign reductant. [ABSTRACT FROM AUTHOR]

Very small (∼2 nm) silver nanoparticles can be readily prepared using p-phosphonated calixarenes as templating agents and surfactants, at the same time allowing the use of hydrogen gas as an environmentally benign reductant. [ABSTRACT FROM AUTHOR]

Atera Fault clay gouges were collected for age dating near Kawaue, Nakatsugawa City, Central Japan, and the results integrated within its complex geological history. The results form an internally consistent data set constrained by extensive geochronological data (AFTA, ZFTA, CHIME) and support the application of gouge dating in constraining timing of brittle deformation in Central Japan. The Atera illite age data complete recently obtained limited illite fault gouge age data from underground exposure in the Toki Granite; the new illite age data are identical within error. The age of the heterogenous welded tuff breccia zone (Atera 1) ranges from 40.6 ± 1.0 Ma to 60.0 ± 1.4 Ma, whereas ages of the fault core gouge sample (Atera 2) range from 41.8 ± 1.0 Ma to 52.7 ± 1.2 Ma. The finest < 0.1 µm fraction of the fault breccia and fault core gouge yield ages around 41 Ma, identical within error. The new illite age data indicate brittle faulting and a following geothermal event occurring in the Paleogene–Eocene, similar to the nearby Toki Granite area and confirm they were both synchronous with a post-intrusive pluton exhumation. The Atera Fault illite age data provide additional insights into an integrated, regional-scale record of the tectonic displacement of Central Japan and might be influenced by large-scale tectonic processes such as the Emperor sea mount kink around 55 to 46 Ma with fault initiation around 50 Ma and brittle fault cessation or reactivation around 40 Ma in the Eocene. [ABSTRACT FROM AUTHOR]

Xenocrysts and xenoliths in Upper Cretaceous pyroclastics on Mount Carmel (northern Israel) represent a series of similar magma-fluid systems at different stages of their evolution, recording a continuous decrease in oxygen fugacity (fO2) as crystallization proceeded. Corundum coexisting with Fe-Mg-Cr-Al spinels, other Fe-Mg-Al-Na oxides, and Fe-Ni alloys in apparent cumulates crystallized at fO2 values near the iron-wüstite (IW) buffer (fO2 = IW±1) and is zoned from high-Cr cores to lower-Cr rims, consistent with fractional crystallization trends. The reconstructed parental melts of the cumulates are Al-Cr-Fe-Mg oxides with ca. 2 wt% SiO2. Corundum in other possible cumulates that contain Cr-Fe (Fe 45 wt%) alloys has low-Cr cores and still lower-Cr rims. Corundum coexisting with Cr0 (fO2 = IW-5) in some possible cumulates has low-Cr cores, but high-Cr rims (to >30% Cr2O3). These changes in zoning patterns reflect the strong decrease in the melting point of Cr2O3, relative to Al2O3, with decreasing fO2. The electron energy loss spectroscopy (EELS) analyses show that all Cr in corundum that coexists with Cr0 is present as Cr3+. This suggests that late in the evolution of these reduced melts, Cr2+ has disproportionated via the reaction 3Cr2+(melt) → 2Cr3+(Crn) + Cr0. The most Cr-rich corundum crystallized together with β-alumina phases including NaAl11O17 (diaoyudaoite) and KAl11O17 (kahlenbergite) and β″-alumina phases; residual melts crystallized a range of (K,Mg)2(Al,Cr)10O17 phases with the kahlenbergite structure. The parental melts of these assemblages appear to have been Al-Cr-K-Na-Mg oxides, which may be related to the Al-Cr-Fe-Mg oxide melts mentioned above, through fractional crystallization or liquid immiscibility. These samples are less reduced (fO2 from IW to IW-5) than the assemblages of the trapped silicate melts in the more abundant xenoliths of corundum aggregates (fO2 = IW-6 to IW-10). They could be considered to represent an earlier stage in the fO2 evolution of an "ideal" Mt. Carmel magmatic system, in which mafic or syenitic magmas were fluxed by mantle-derived CH4+H2 fluids. This is a newly recognized step in the evolution of the Mt. Carmel assemblages and helps to understand element partitioning under highly reducing conditions. [ABSTRACT FROM AUTHOR]

Reports on the helium or (3)He nuclear magnetic resonance spectroscopy of the endohedral compounds (3)HeC(60) and (3)HeC(70). Introduction of helium into C(60) and C(70); Analysis of the ring currents and the aromaticity in fullerenes; Magnetic susceptibility of C(60) and C(70); Shielding contribution in the (3)He nuclei encapsulated in C(60) and C(70).

Presents a study on the response of fullerenes, prepared via the standard method (an arc between graphite electrodes in a partial pressure of helium), to high temperature heating. Release of 4He and 3He; No exchange with the atmosphere; Theory of a mechanism involving reversibly breaking one or more bonds to temporarily open a `window' in the cage; More.

Electrode/electrolyte interface plays a critical role in the performance and stability of solid oxide fuel cells (SOFCs). In the case of La 0·6 Sr 0·4 Co 0·2 Fe 0·8 O 3-δ (LSCF) cathode, it is well known that cathodic polarization promotes the Sr segregation and diffusion towards the LSCF electrode and Y 2 O 3 –ZrO 2 (YSZ) electrolyte interface, leading to the formation of SrZrO 3 secondary phase and the disintegration of LSCF structure at the interface. On the other hand, LSCF is chemically stable with doped ceria electrolytes such as Gd-doped CeO 2 (GDC). However, there appears no comparative studies on the intrinsic relationship between the surface segregation, interface reaction and stability of LSCF in YSZ and GDC electrolytes. Here, a comparative study has been carried out on the segregation and interface formation of LSCF on GDC and YSZ electrolyte under identical cathodic polarization conditions at 750 °C and 1000 mAcm−2 using focused ion beam and scanning transmission electron microscopy (FIB-STEM) techniques. Segregation of Sr occurs in the LSCF-GDC system, however, the inertness of GDC electrolyte suppresses the segregation process of Sr species. Instead, surface segregation of B-site Co cation becomes dominant under the cathodic polarization, forming isolated CoO x particles. The results indicate that the existence of chemical catchers such as Zr in the case of YSZ electrolyte for the segregated Sr species is kinetically the driving force for the Sr segregation and stability of LSCF electrodes under SOFC operation conditions. • LSCF/GDC and LSCF/YSZ electrodes were studied under identical conditions. • Cathodic polarization induces the surface segregation of Sr in both electrodes. • Sr segregation of LSCF/GDC is inhibited due to the inert of GDC electrolyte. • Presence of catches such as Zr is the driving force for Sr segregation of LSCF/YSZ. [ABSTRACT FROM AUTHOR]

We report a study on multiferroic bismuth ferrite (BiFeO3, BFO)-ferromagnetic lanthanum strontium manganese oxide (La0.7Sr0.3MnO3, LSMO) epitaxial interfaces by scanning transmission electron microscopy-energy dispersive spectroscopy (STEM-EDS) and energy-filtered transmission electron microscopy (EFTEM). Epitaxial (001) oriented LSMO/BFO heterostructures were fabricated on a (001) strontium titanate (SrTiO3, STO) substrate using pulsed laser deposition (PLD). Different cooling conditions to room temperature (rapid or slow) were used to investigate the effect of fabrication conditions on the structural quality of the interfaces. The combined analysis of bright field transmission electron microscopy imaging, STEM-EDS and EFTEM data reveals that the LSMO-BFO heterostructure interface is free from any defects but the phases are chemically interdiffused over a length scale of ∼4 nm. [ABSTRACT FROM AUTHOR]

A personal narrative is presented which explores the author's experience working as a librarian in the National Demonstration Centre at Pontefract General Infirmary in West Yorkshire, Great Britain.

Abstract The establishment of intimate electrode/electrolyte interface is very important in solid oxide fuel cells (SOFCs), because it plays a critical role in the overall cell performance and durability. In this study, Mn segregation and interface formation between directly assembled La 0.8 Sr 0.2 MnO 3 (LSM) electrode and yttrium-stabilized zirconia (YSZ) or gadolinium-doped ceria (GDC) electrolytes are studied using combined focused ion beam and scanning transmission electron microscopy (FIB-STEM). In the case of LSM/YSZ and LSM/GDC electrodes, a significant reduction in the electrode ohmic resistance is observed after cathodic polarization at 900 °C and 500 mA cm−2, indicating the formation of an intimate interface. However, LSM particles start to disintegrate at the electrode/electrolyte interface with the increase of polarization time in the case of LSM/YSZ electrode. On the other hand, the LSM/GDC interface is very stable with negligible microstructure change at the interface. Mn segregation from the LSM perovskite structure is identified under the influence of polarization in both LSM/YSZ and LSM/GDC electrodes. The results demonstrate that nature of the electrolyte plays a critical role in the electrochemical activity, microstructure, morphology and stability of LSM/electrolyte interface under SOFC operation conditions. Highlights • LSM/YSZ and LSM/GDC electrodes were prepared by direct assembly method. • Cathodic polarization induces the interface formation and Mn segregation. • The change in the microstructure of LSM/YSZ interface is substantial. • Nature of electrolyte plays an important role in the microstructure and stability of the interface. [ABSTRACT FROM AUTHOR]

The article presents the study that evaluates the efficacy of using ubiquitious, iodine complex, starch to assemble C70 fullerene into nanorings. To form these rings, researchers used self-assembled structures as nanoreactors in which silver nanoparticles are prepared. They also discovered an unusual self-assembly of C70 nanorings in water when they used amylose helix as template caused by the anisotropic shape of C70.

The article discusses the result of a study concerning optimization of the signal enhancement in cryogenic ex situ dynamic nuclear polymerization (DNP)-nuclear magnetic resonance (NMR) spectroscopy. The findings suggest a primary role for methyl groups in the context of DNP experiment carried out at very low temperature.

The reproducible synthesis of boron nitride (BN) nano-onions by lamp ablation is reported, exclusively from hexagonal BN precursor powder in vacuum, in a one-pot procedure that is free of toxic or harmful reagents, uncomplicated, potentially scalable and rapid. A high-resolution Scanning Electron Microscope image shows a "forest" of such nano-onions as they evolve between precursor flakes. A Transmission Electron Microscope image illustrates the range of nano-onion sizes and shapes. A coarse schematic of the proposed formation mechanism is also shown. [Display omitted] We report the generation of boron nitride nano-onions (BNNOs) from pure hexagonal-BN crystallite powder in vacuum, via a one-pot, non-toxic, catalyst-free, rapid and potentially scalable high-temperature lamp ablation procedure. An array of characterization procedures revealed nanoparticle (a) shapes and sizes, morphing from polyhedral for diameters of order 101 nm to quasi-spherical at diameters of order 102 nm, and (b) composition, with a 1:1 B:N ratio while also confirming the absence of contaminants. A formation mechanism is proposed whereby BNNOs evolve from the initial thermal exfoliation of the bulk precursor powder into nano-platelets. They fold and close into hollow nano-cages that are more stable thermodynamically. Reactor temperatures were measured to be ∼ 1500–1600 K for experiments yielding the largest amounts of BNNOs. A relatively narrow range of ∼ 1300–1800 K can be established for viable BNNO generation. Structural modeling sheds light on the relative stability of the nanostructures as a function of shape, size and number of layers. [ABSTRACT FROM AUTHOR]

The ∼3.48 billion-year-old Dresser Formation, Pilbara Craton, Western Australia, is a key geological unit for the study of Earth's earliest life and the habitats it occupied. Here, we describe a new suite of spheroidal to lenticular microstructures that morphologically resemble some previously reported Archean microfossils. Correlative microscopy shows that these objects have a size distribution, wall ultrastructure, and chemistry that are incompatible with a microfossil origin and instead are interpreted as pyritized and silicified fragments of vesicular volcanic glass. Organic kerogenous material is associated with much of the altered volcanic glass; variable quantities of organic carbon line or fill the insides of some individual vesicles, while relatively large, tufted organic-rich laminae envelop multiple vesicles. The microstructures reported herein constitute a new type of abiogenic artifact (pseudo-fossil) that must be considered when evaluating potential signs of early life on Earth or elsewhere. In the sample studied here, where hundreds of these microstructures are present, the combined evidence permits a relatively straightforward interpretation as vesicular volcanic glass. However, reworked, isolated, and silicified microstructures of this type may prove particularly problematic in early or extraterrestrial life studies since they adsorb carbon onto their surfaces and are readily pyritized, mimicking a common preservation mechanism for bona fide microfossils. In those cases, nanoscale analysis of wall ultrastructure would be required to firmly exclude a biological origin. Key Words: Microfossils—Pseudo-fossils—Volcanic vesicles—Archean life—Pilbara Craton—Dresser Formation. Astrobiology 18, 539–555. [ABSTRACT FROM AUTHOR]

Core-shell Cu/γ-Fe2O3@C and yolk-shell-structured Cu/Fe@γ-Fe2O3@C particles are prepared by a facile synthesis method using copper oxide as template particles, resorcinol-formaldehyde as the carbon precursor, and iron nitrate solution as the iron source via pyrolysis. With increasing carbonization temperature and time, solid γ-Fe2O3 cores are formed and then transformed into Fe@γ-Fe2O3 yolk-shell-structured particles via Ostwald ripening under nitrogen gas flow. The composition variations are studied, and the formation mechanism is proposed for the generation of the hollow and yolk-shell-structured metal and metal oxides. Moreover, highly graphitic carbons can be obtained by etching the metal and metal oxide nanoparticles through an acid treatment. The electrocatalytic activity for oxygen reduction reaction is investigated on Cu/γ-Fe2O3@C, Cu/Fe@γ-Fe2O3@C, and graphitic carbons, indicating comparable or even superior performance to other Fe-based nanocatalysts. [ABSTRACT FROM AUTHOR]

Microtubes within 145 Ma volcanic glass from the Argo Abyssal Plain possess intriguing internal microtextures that under light microscopy resemble biological septa and ovoid microbial cells. These microtextures have previously been used as part of a suite of evidence to support the biogenicity of such microtubes, and similar textures are beginning to be used in attempts to taxonomically classify microtubes from both the modern and ancient oceanic crust within an ichnofossil (trace fossil) hierarchy. Here we use high spatial resolution correlative microscopy to characterize the morphology and chemistry of the Argo microtubes in order to critically assess the origin of these microtextures and increase our understanding of the potential formation mechanisms of microtubes in volcanic glass. Electron microscopy shows that the microtubes contain abundant elongated void spaces and when these are reconstructed in three dimensions they closely replicate the morphology and distribution of the previously described ‘septa’. No organic material is associated with the void spaces and so we reinterpret the ‘septa’ as cracks within the clay mineral phase that infills the microtubes, probably formed during sample collection and/or preparation. One ovoid body also appears to correlate with void space but further data are required to substantiate such an origin. We caution that the study of micro-textures within volcanic glass-hosted microtubes by optical microscopy alone may be misleading, hence each individual occurrence should be subject to detailed micro- to nano-scale in situ morphological and chemical investigation before being used as a potential biosignature. Several microtubes do contain elevated levels of carbon, typically found within amorphous carbonate minerals that, along with nontronite clay, have precipitated within the microtubes. One microtube contains organic carbon; this is heterogeneously distributed, occurs away from void spaces and is spatially associated with elevated levels of titanium. This organic carbon could originate from in situ biological activity but it could also have been introduced by circulating seawater. Titanium adsorbed onto this organic material may provide a titanium source for the commonly observed titanite mineralization found in ancient volcanic glass-hosted microtubes within greenstone belts and ophiolites that have experienced low grade metamorphism. Elemental enrichments and depletions in three chemically distinct regions (glass, alteration rim, and tube interior) provide further insights into microtube formation mechanisms. Alteration rims have sharply defined edges, are about 0.1 μm wide independent of microtube diameter, and are primarily composed of Si, Al, O ± Ti. The tube interiors are depleted in Si and Al, and most other elements (Ca, Mg, Na, Mn) relative to fresh glass but K and Fe may be enriched. There is no evidence for depletion of elements in the glass immediately exterior to the alteration rim. This favours a mechanism whereby microtubes grow by increasing in length, rather than increasing in diameter. In this model protons are the major agent of glass alteration and the supply of protons and the kinetics of the formation of the Si-Al alteration rim control the diameter of the microtubes. [ABSTRACT FROM AUTHOR]

Focuses on the importance of 3helium (3He) nuclear magnetic resonance spectroscopy (NMR) in studying the chemistry of fullerene. Properties of fullerene.

Investigates the spectroscopic and other properties of several noble gas compounds by increasing the fraction of fullerene molecules occupied. Preparation of the specimens.

A letter to the editor is presented about tobacco sales laws.

It is known that large elastic lattice strain, which is a measure of the distortion of the interatomic bonds in solids, can influence the many physical and chemical properties of materials. However, it is not as easy to achieve ultra-large elastic strains close to their theoretical limits in bulk engineering materials as it is for nanomaterials. A breakthrough was made in a bulk NiTi–Nb composite in which Nb nanowires were induced to sustain ultra-large elastic lattice strains up to 6.5% by the martensitic transformation of the NiTi matrix via the principles of "lattice strain matching" and "collective atomic load transfer". This study was conducted to trial out these novel concepts in an in situ NiTi–Nb 3 Sn eutectic composite system. The intermetallic A15-Nb 3 Sn is a very brittle compound and is widely used as a superconductor. Therefore, this study offers three new aspects: (i) it tests out the applicability of the principle of lattice strain matching for inducing ultra-large elastic strains in brittle materials, (ii) it investigates a material of high potential use, and (iii) it explores a novel fabrication approach for in-situ composites via eutectic solidification. The Nb 3 Sn lamellae in the composites were found to achieve large elastic lattice strains up to ∼2.4%, which are an order of magnitude higher than what may be expected of free-standing Nb 3 Sn or 3–4 times what have been achieved in Nb 3 Sn microfilaments embedded in other metal matrices, demonstrating the extraordinary effect of the NiTi martensitic transformation matrix. The micromechanical behaviours of lattice strain evolutions of the two phases were investigated by in-situ synchrotron x-ray diffraction analysis. [ABSTRACT FROM AUTHOR]

Hydrogen peroxide (H 2 O 2 ) sensing has many biomedical, healthcare and industrial applications. However, H 2 O 2 sensors are limited in sensitivity and selectivity. Here, we investigate the application of magnetite (Fe 3 O 4 ) coated gold nanorods (GNRs) of two aspect ratios as active glassy carbon electrode modifiers for the fabrication of H 2 O 2 electrochemical sensors. We show that the GNR-Fe 3 O 4 nanohybrids of a smaller aspect ratio (1.6) outperform the longer GNRs (aspect ratio 7.5) in the electrochemical detection of H 2 O 2 , as measured using cyclic voltammetry (CV) and amperometric techniques. The synthesized GNR-Fe 3 O 4 in this study also demonstrated high sensitivity and selectivity, with performance surpassing previously reported H 2 O 2 sensors. [ABSTRACT FROM AUTHOR]

Ternary alloy PtRuCo x nanoparticles (NPs) with Co-rich core and PtRu skinned shell on carbon nanotubes (CNTs) have been successfully synthesized as electrocatalysts for methanol oxidation reaction (MOR) of direct methanol fuel cells (DMFCs) via a successive dealloying and annealing treatment of PtRuCo alloy particles. The best results were obtained on dealloyed PtRuCo x NPs annealed at 450 °C in argon with x = 0.48, characterizing by a ∼1 nm thick Co-free PtRu shell. The core–shell structured PtRuCo x catalysts exhibit a high activity for MOR, 400 A g −1 pt measured at 0.40 V (vs Ag/AgCl), almost 4 times higher than 104 A g −1 Pt for the reaction on the PtRuCo alloy before deallaying and annealing treatment. The core–shell structured PtRuCo x NPs also show excellent structural stability; maintaining 74% of the activity after 1000 cycle between −0.2 to 1.0 V ( vs . Ag/AgCl), significantly higher than 49% for PtRuCo and 25% for the conventional PtRu/C catalysts. The results demonstrate that the successive dealloying and annealing treatment is very effective to synthesize core–shell structured PtRuCo x ternary alloy electrocatalysts with high activity and durability for DMFCs. [ABSTRACT FROM AUTHOR]

The study of isolated atoms or molecules inside a fullerene cavity provides a unique environment. It is likely to control the outer carbon cage and study the isolated species when molecules or atoms are trapped inside a fullerene. We report the Diels–Alder addition reaction of 9,10-dimethyl anthracene (DMA) to H2@C60 while 1H NMR spectroscopy is utilized to characterize the Diels–Alder reaction of the DMA with the fullerene. Through 1H NMR spectroscopy, a series of isomeric adducts are identified. The obtained peaks are sharp, precise, and straightforward. Moreover, in this paper, H2@C60 and its isomers are described for the first time. [ABSTRACT FROM AUTHOR]

Phosphatic grains of the shallow marine phosphorite deposits of Egypt are classified as either phosphatic bioclasts preserving biological structure (e.g. skeletal fragments such as fish bones and teeth) or phosphatic peloids and intraclasts. This study describes the destructive and constructive microbial pathways represented by bioerosion of bones by endolithic cyanobacteria and accretion of phosphatic peloids by bacteria. The palaeoenvironmental conditions and post-depositional/diagenetic history of these grains have also been considered. Scanning and transmission electron microscopy showed that the phosphatic peloids under transmitted light microscopy are composed mainly of microspheres (0.5 to 2.5 μm) similar in shape and size to coccoid-like bacteria. Chemical mapping showed that these microspheres are composed of carbonate-fluorapatite (CFA) and surrounded by degraded carbonaceous matrix. These grains are suggested to be reworked from pre-existing microbial mats during transgressive–regressive cycles affecting the southern Tethyan Campanian–Maastrichtian shallow continental shelf. The bioerosion of phosphatic bones is characterized by a network of meandering microborings that penetrated inward from the bone surface by endolithic cyanobacteria. The bioerosion of bones resulted in a gradual centripetal digestion and conversion of bones into micritic phosphate peloids. The bioerosion mechanism is probably started in the acidic sheath surrounding cyanobacteria followed by supersaturation of PO 4 and reprecipitation of crystalline CFA as electron dense remineralized rims. Electron microprobe microanalyses showed that the remineralized microbored areas are higher in CaO, P 2 O 5 , and F and depleted in Cl, relative to unaltered bones. A gradual demineralization of remineralized rims followed by dissolution of cyanobacterial cells is probably occurred during diagenesis and meteoric water alteration leaving behind empty microborings. Bone exposed to meteoric water alteration is lower in CaO and P 2 O 5 and higher in F and Cl than the unaltered bones. Understanding bone bioerosion has significant implications for palaeoenvironmental and taphonomic reconstruction, archaeological applications and a regional correlation of the late Cretaceous to Palaeogene phosphogenic province extending from Middle East to North Africa. [ABSTRACT FROM AUTHOR]

New analytical approaches and discoveries are demanding fresh thinking about the early fossil record. The 1.88-Ga Gunflint chert provides an important benchmark for the analysis of early fossil preservation. High-resolution analysis of Gunflintia shows that microtaphonomy can help to resolve long-standing paleobiological questions. Novel 3D nanoscale reconstructions of the most ancient complex fossil Eosphaera reveal features hitherto unmatched in any crown-group microbe. While Eosphaera may preserve a symbiotic consortium, a stronger conclusion is that multicellular morphospace was differently occupied in the Paleoproterozoic. The 3.46-Ga Apex chert provides a test bed for claims of biogenicity of cell-like structures. Mapping plus focused ion beam milling combined with transmission electron microscopy data demonstrate that microfossil-like taxa, including species of Archaeoscillatoriopsis and Primaevifilum, are pseudofossils formed from vermiform phyllosilicate grains during hydrothermal alteration events. The 3.43-Ga Strelley Pool Formation shows that plausible early fossil candidates are turning up in unexpected environmental settings. Our data reveal how cellular clusters of unexpectedly large coccoids and tubular sheath-like envelopes were trapped between sand grains and entombed within coatings of dripstone beach-rock silica cement. These fossils come from Earth's earliest known intertidal to supratidal shoreline deposit, accumulated under aerated but oxygen poor conditions. [ABSTRACT FROM AUTHOR]