A-site Ordering versus Electronic Inhomogeneity in CMR-Manganite Films

Epitaxial La3/4Ca1/4MnO3/MgO(100) (LCMO) thin films show unusual rhombohedral (R-3c) structure with a new perovskite superstructure due to unique ordering of La and Ca at the A-site positions. Very sharp insulator-metal and para-ferromagnetic phase transitions at temperatures up to TMI ~ TC=295 K were observed. The ordered films were electronically homogeneous down to 1 nm scale as revealed by scanning tunnelling microscopy/spectroscopy. In contrast, orthorhombic and A-site disordered LCMO demonstrate broadened phase transitions as well as mesoscopic phase separation for T<<TC. The unique La/Ca ordering suppresses cation mismatch stress within one super-cell, a~1.55 nm, enhancing electronic homogeneity. Phase separation scenario seems not to be a unique mechanism for CMR as very large CMR=500 % was also observed in A-site ordered films.Comment: We have added two references and additional sentence

Partial Covering Arrays: Algorithms and Asymptotics

A covering array $\mathsf{CA}(N;t,k,v)$ is an $N\times k$ array with entries in $\{1, 2, \ldots , v\}$, for which every $N\times t$ subarray contains each $t$-tuple of $\{1, 2, \ldots , v\}^t$ among its rows. Covering arrays find application in interaction testing, including software and hardware testing, advanced materials development, and biological systems. A central question is to determine or bound $\mathsf{CAN}(t,k,v)$, the minimum number $N$ of rows of a $\mathsf{CA}(N;t,k,v)$. The well known bound $\mathsf{CAN}(t,k,v)=O((t-1)v^t\log k)$ is not too far from being asymptotically optimal. Sensible relaxations of the covering requirement arise when (1) the set $\{1, 2, \ldots , v\}^t$ need only be contained among the rows of at least $(1-\epsilon)\binom{k}{t}$ of the $N\times t$ subarrays and (2) the rows of every $N\times t$ subarray need only contain a (large) subset of $\{1, 2, \ldots , v\}^t$. In this paper, using probabilistic methods, significant improvements on the covering array upper bound are established for both relaxations, and for the conjunction of the two. In each case, a randomized algorithm constructs such arrays in expected polynomial time

UK Geoenergy Observatories Glasgow: GGC01 cored, seismic monitoring borehole – final data release

This report provides an overview of information contained in the final data release for the UK Geoenergy Observatories Glasgow borehole GGC01. This final data release supersedes the initial and intermediate data releases (Starcher et al. 2019; Kearsey et al. 2019). It includes additional information on core scan data and core-wireline depth integration. The cored, seismic monitoring borehole GGC01 (BGS SOBI number NS66SW BJ 3754, BGS ID 20650619) was drilled between 19 November and 12 December 2018 producing a core of 102 mm diameter. The borehole was wireline logged in December 2018 and a string of 5 seismometers were installed in February 2019. The core was transported to the National Geological Repository (NGR) at BGS Keyworth and was curated into 1 m core boxes. State-of-the-art core scanners have been used to collect along core datasets. This final data release includes optical images (whole core and slabbed core), radiographic images, MSCL-S (geophysical), NIR and XRF (mineralogical and chemical) core scan data. Also included in this final release is the material from the previous releases including sedimentary, discontinuity and engineering logs, wireline/geophysical downhole logs, drillers’ logs and sample information

UK Geoenergy Observatories Glasgow: GGC01 cored, seismic monitoring borehole – intermediate data release

This report gives an overview of information related to an intermediate data release of the borehole information pack for UK Geoenergy Observatories: Glasgow borehole GGC01. The cored, seismic monitoring borehole GGC01 (BGS SOBI number NS66SW BJ 3754, BGS ID 20650619) was drilled between 19 November and 12 December 2018 producing a core of 102 mm diameter. The borehole was wireline logged in December 2018 and a string of 5 seismometers were installed in February 2019. The core was transported to the National Geological Repository (NGR) at BGS Keyworth and was curated into 1 m core boxes. State-of-the-art core scanners are being used to collect radiographic, CT, optical images, geophysical log and XRF along core datasets. Optical images and radiographic images are included in the intermediate release. Also included are sedimentary, discontinuity and engineering log

Initial results of coring at Prees, Cheshire Basin, UK (ICDP JET project): towards an integrated stratigraphy, timescale, and Earth system understanding for the Early Jurassic

This is the final version. Available on open access from Copernicus Publications via the DOI in this recordData availability: Full core scan data (https://doi.org/10.5285/91392f09-25d4-454c-aece-56bde0dbf3ba, BGS Core Scanning Facility, 2022) will be available after 1 November 2024 via the Natural Environment Research Council (NERC) National Geoscience Data Centre (https://webapps.bgs.ac.uk/services/ngdc/accessions/index.html#, last access: 12 October 2023). Downhole logging data (https://doi.org/10.5880/ICDP.5065.001​​​​​​​, Wonik, 2023) will be made available via the ICDP (https://www.icdp-online.org/projects/by-continent/europe/jet-uk/, last access: 12 October 2023). The JET Operational Report is published as Hesselbo et al. (2023); full information about the operational dataset, the logging dataset, data availability and the explanatory remarks is available on the ICPD-JET project website: https://www.icdp-online.org/projects/by-continent/europe/jet-uk/ (last access: 12 October 2023). A subset of data, additional biostratigraphic tables, and vector graphics files for Figs. 3–5 are included as the Supplement. Supplementary Data File 1 tabulates the corrected depth scale for Prees 2C. Supplementary Data File 2 summarizes the ammonite-based chronostratigraphy of the Prees 2 cores (ammonite identifications by Kevin N. Page). Supplementary Data File 3 summarizes the ammonite-based chronostratigraphy for the Hettangian to Early Pliensbachian of the Llanbedr (Mochras Farm) borehole (updated by Kevin N. Page). Supplementary Data File 4 tabulates the organic carbon-isotope ratios, TOC, and carbonate content of low-resolution samples taken at the Prees drill site; TOC and carbonate data are calculated using calibration based on portable XRF (Supplementary Data File 5) and a gas source isotope ratio mass spectrometer (Supplementary Data File 6). Supplementary Data File 5 tabulates portable XRF results for bulk rock powders of low-resolution samples taken at the Prees drill site; uncertainties stated in the table are given for the fit to the raw data and do not reflect the true reproducibility of the data. Empty fields indicate values under the detection limit. Sample SSK116001 acted as a repeat sample which was measured 70 times over the course of the data acquisition to determine the repeatability and drift of the instrument. LE stands for “light elements”. Supplementary Data File 6 tabulates gas source isotope ratio mass spectrometry (GS-IRMS) data (oxygen- and carbon-isotope ratios of carbonate as well as carbonate content calculated as calcite) for a set of 24 samples covering the entire core length and reflecting a representative spread of carbonate content. Comparison of GS-IRMS data with p-XRF data was used to create a calibration curve to calculate the carbonate (and TOC) content of all low-resolution samples. Supplementary Data File 7 tabulates pyrolysis data (Rock-Eval 6) for Prees 1 well cuttings and Wilkesley borehole samples. Supplementary Data File 8 contains vector graphics files (.svg) for Figs. 3–5.Drilling for the International Continental Scientific Drilling Program (ICDP) Early Jurassic Earth System and Timescale project (JET) was undertaken between October 2020 and January 2021. The drill site is situated in a small-scale synformal basin of the latest Triassic to Early Jurassic age that formed above the major Permian–Triassic half-graben system of the Cheshire Basin. The borehole is located to recover an expanded and complete succession to complement the legacy core from the Llanbedr (Mochras Farm) borehole drilled through 1967–1969 on the edge of the Cardigan Bay Basin, North Wales. The overall aim of the project is to construct an astronomically calibrated integrated timescale for the Early Jurassic and to provide insights into the operation of the Early Jurassic Earth system. Core of Quaternary age cover and Early Jurassic mudstone was obtained from two shallow partially cored geotechnical holes (Prees 2A to 32.2 m below surface (m b.s.) and Prees 2B to 37.0 m b.s.) together with Early Jurassic and Late Triassic mudstone from the principal hole, Prees 2C, which was cored from 32.92 to 651.32 m (corrected core depth scale). Core recovery was 99.7 % for Prees 2C. The ages of the recovered stratigraphy range from the Late Triassic (probably Rhaetian) to the Early Jurassic, Early Pliensbachian (Ibex Ammonoid Chronozone). All ammonoid chronozones have been identified for the drilled Early Jurassic strata. The full lithological succession comprises the Branscombe Mudstone and Blue Anchor formations of the Mercia Mudstone Group, the Westbury and Lilstock formations of the Penarth Group, and the Redcar Mudstone Formation of the Lias Group. A distinct interval of siltstone is recognized within the Late Sinemurian of the Redcar Mudstone Formation, and the name “Prees Siltstone Member” is proposed. Depositional environments range from playa lake in the Late Triassic to distal offshore marine in the Early Jurassic. Initial datasets compiled from the core include radiography, natural gamma ray, density, magnetic susceptibility, and X-ray fluorescence (XRF). A full suite of downhole logs was also run. Intervals of organic carbon enrichment occur in the Rhaetian (Late Triassic) Westbury Formation and in the earliest Hettangian and earliest Pliensbachian strata of the Redcar Mudstone Formation, where up to 4 % total organic carbon (TOC) is recorded. Other parts of the succession are generally organic-lean, containing less than 1 % TOC. Carbon-isotope values from bulk organic matter have also been determined, initially at a resolution of ∼ 1 m, and these provide the basis for detailed correlation between the Prees 2 succession and adjacent boreholes and Global Stratotype Section and Point (GSSP) outcrops. Multiple complementary studies are currently underway and preliminary results promise an astronomically calibrated biostratigraphy, magnetostratigraphy, and chemostratigraphy for the combined Prees and Mochras successions as well as insights into the dynamics of background processes and major palaeo-environmental changes.ICDPNatural Environment Research Council (NERC)German Research FoundationHungarian Scientific Research FundNational Science Centre, PolandPolish Geological Institut

Direct imaging of lattice-strain-induced stripe phases in an optimally doped manganite film

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