New age constraints on the Lower Jurassic Pliensbachian–Toarcian Boundary at Chacay Melehue (Neuquén Basin, Argentina)

The Pliensbachian–Toarcian boundary interval is characterized by a ~ 3‰ negative carbon-isotope excursion (CIE) in organic and inorganic marine and terrestrial archives from sections in Europe, such as Peniche (Portugal) and Hawsker Bottoms, Yorkshire (UK). A new high-resolution organic-carbon isotope record, illustrating the same chemostratigraphic feature, is presented from the Southern Hemisphere Arroyo Chacay Melehue section, Chos Malal, Argentina, corroborating the global significance of this disturbance to the carbon cycle. The negative carbon-isotope excursion, mercury and organic-matter enrichment are accompanied by high-resolution ammonite and nannofossil biostratigraphy together with U–Pb CA-ID-TIMS geochronology derived from intercalated volcanic ash beds. A new age of ~ 183.73 + 0.35/− 0.50 Ma for the Pliensbachian–Toarcian boundary, and 182.77 + 0.11/− 0.15 for the tenuicostatum–serpentinum zonal boundary, is assigned based on high-precision U–Pb zircon geochronology and a Bayesian Markov chain Monte Carlo (MCMC) stratigraphic age model

Anisotropy studies around the galactic centre at EeV energies with the Auger Observatory

Data from the Pierre Auger Observatory are analyzed to search for anisotropies near the direction of the Galactic Centre at EeV energies. The exposure of the surface array in this part of the sky is already significantly larger than that of the fore-runner experiments. Our results do not support previous findings of localized excesses in the AGASA and SUGAR data. We set an upper bound on a point-like flux of cosmic rays arriving from the Galactic Centre which excludes several scenarios predicting sources of EeV neutrons from Sagittarius $A$. Also the events detected simultaneously by the surface and fluorescence detectors (the `hybrid' data set), which have better pointing accuracy but are less numerous than those of the surface array alone, do not show any significant localized excess from this direction.Comment: Matches published versio

Mochras borehole revisited: a new global standard for Early Jurassic earth history

The Early Jurassic epoch was a time of extreme environmental change: there are well-documented examples of rapid transitions from cold, or even glacial, climates to super greenhouse events, the latter characterized worldwide by hugely enhanced organic carbon burial, multiple large isotopic anomalies, global sea-level change, and mass extinction (Price, 1999; Hesselbo et al., 2000; Jenkyns, 2010; Korte and Hesselbo, 2011). These icehouse–greenhouse events not only reflect changes in the global climate system but are also thought to have had significant influence on the evolution of Jurassic marine biota (e.g. van de Schootbrugge et al., 2005; Fraguas et al., 2012). Furthermore, the events may serve as analogues for present-day and future environmental transitions

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

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

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 32.2g¯m below surface (mg¯b.s.) and Prees 2B to 37.0g¯mg¯b.s.) together with Early Jurassic and Late Triassic mudstone from the principal hole, Prees 2C, which was cored from 32.92 to 651.32g¯m (corrected core depth scale). Core recovery was 99.7g¯% 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 4g¯% total organic carbon (TOC) is recorded. Other parts of the succession are generally organic-lean, containing less than 1g¯% TOC. Carbon-isotope values from bulk organic matter have also been determined, initially at a resolution of g1/4g¯1g¯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

The choice of a suitable oligosaccharide to prevent aggregation of PEGylated nanoparticles during freeze thawing and freeze drying

In a previous Study we have shown that the oligosaccharide inulin can prevent aggregation of poly(ethylene glycol) (PEG) coated plasmid DNA/cationic liposome complexes ('' PEGylated lipoplexes '') during freeze thawing and freeze drying [Hinrichs et al., 2005. J. Control. Release 103, 465]. By contrast, dextran clearly failed as stabilizer. These results were ascribed to the fact that inulin and PEG are compatible while dextran and PEG are not. In this study the stabilizing capacities of inulin and dextran (of various molecular weights) during freeze thawing and freeze drying Of four different types of nanoparticles, each type with different amounts of PEG at their surface, were investigated. Freeze drying and freeze thawing of 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP)/dioleoyl-phosphatidyl-ethanolamine (DOPE) liposomes and egg phosphatidyl choline (EPC/cholesterol (CHOL) liposomes showed that inulins are excellent stabilizers even for highly PEGylated liposomes while (especially higher molecular weight) dextrans dramatically lost their stabilizing capacity when increasing the degree of PEGylation of the liposomes. The same results were obtained for plasmid DNA/DOTAP/DOPE complexes. Finally, both inulin and dextran Could prevent full aggregation of plasmid DNA/polyethylenimine (PEI) complexes independent whether PEI was PEGylated or not. It is concluded that inulins are preferred as stabilizers over dextrans for various types of PEGylated nanoparticles clue to their compatibility with PEG. (c) 2006 Elsevier B.V. All rights reserved.</p

Diffuse cavernous hemangioma of the rectum: an atypical cause of rectal bleeding Hemangioma cavernoso difuso del recto: una causa atípica de hemorragia digestiva baja

Objective: cavernous hemangioma of the rectosigmoid colon is a rare disease, with no more than 200 cases reported in the literature. The rectosigmoid is the most common site of this disease in the gastrointestinal tract. Case report: we report the case of a 31-year-old male with recurrent episodes of rectal bleeding, who was finally diagnosed of diffuse cavernous hemangioma of the rectum. The tumor, of 12 x 10 x 9 cm in size, occupied the rectum to the margin of the anal sphincter. A surgical procedure was ruled out because of the inability to carry out a safe anastomosis while preserving anal sphincters. Discussion: rectal hemangiomas are less frequent vascular malformations. The clinical presentation of a cavernous hemangioma of the rectum is usually acute, recurrent or chronic rectal bleeding. Other symptoms stem from the possible compression or invasion of adjacent structures, such as lumbar or perianal pain, metrorrhage, hematuria, etc. This diagnosis is commonly made in younger patients. Colonoscopy is without doubt the diagnostic technique of choice, and it allows to establish the localization, morphology, and total extension of the lesion; its characteristic image is a red-purplish nodule with great vascular congestion. According to the opinion of most authors, biopsy is not advisable during colonoscopy, since imaging techniques are sufficient for an accurate diagnosis, and the risk of bleeding while manipulating this lesion is not negligible. Computed tomography and particularly magnetic resonance imaging, given their high precision to delimit the lesion and its relations to adjacent structures, are imaging studies that are mandatory before surgical treatment. Other techniques such as selective angiography, barium enema, gastrointestinal transit, and upper-tract endoscopy may be supplementary and help locate more lesions along the gastrointestinal tract. Failure to recognize the exact diagnosis and extent of diffuse cavernous hemangioma may lead to failed surgical treatment and severe complications. Complete surgical excision of the lesion with a sphincter-saving procedure is the primary mode of treatment: conservative proctectomy with coloanal anastomosis.Objetivo: el hemangioma cavernoso rectal constituye una rara patología, de la cual no se han descrito más de 200 casos en la literatura. El recto y colon sigmoide son la localización más frecuente de esta enfermedad en el tracto gastrointestinal. Caso clínico: a continuación presentamos el caso de un varón de 31 años de edad con episodios recurrentes de sangrado digestivo en forma de rectorragias, el cual finalmente fue dignosticado de hemangioma cavernoso difuso rectal. El tumor, de 12 x 10 x 9 cm de tamaño, ocupaba el recto y se extendía hasta el margen del esfínter anal. El tratamiento quirúrgico fue rechazado ante la imposibilidad de llevar a cabo una resección y una anastomosis segura preservando los esfínteres anales. Discusión: los hemangiomas rectales son malformaciones vasculares infrecuentes que se manifiestan en forma de sangrado rectal agudo, crónico o recurrente como primera sintomatología. Otros síntomas vienen derivados de la compresión de estructuras adyacentes como dolor lumbar o perianal, metrorragias, hematuria, etc. El diagnóstico se realiza casi siempre en adultos jóvenes. La colonoscopia es sin duda la prueba diagnóstica de elección, mostrando la extensión, morfología, características del tumor y la típica imagen es la de una formación nodular, rojo-violácea, con gran congestión vascular. De acuerdo con la opinión de la mayoría de los autores, la toma de biopsias durante la endoscopia no está indicada, dado que las técnicas de imagen son suficientes para el diagnóstico y que el riesgo de sangrado durante la manipulación del tumor no es en absoluto despreciable. La TAC y especiamente la RMN permiten definir mejor la lesión y su relación con estructuras adyacentes, siendo primordiales de cara a un tratamiento quirúrgico. El estudio baritado, la arteriografía selectiva mesentérica o la gastroscopia pueden complementar y descartar además patología similar en otras localizaciones del tracto gastrointestinal. El diagnóstico erróneo de hemangioma cavernoso rectal o de su extensión completa puede derivar en un fallo en el tratamiento quirúrgico y graves complicaciones. La completa resección del tumor preservando los esfínteres anales constituye la técnica quirúrgica de elección: proctectomía conservadora con anastomosis coloanal

Bruising of the esophagus as a cause of gastrointestinal bleeding in a case of heatstroke Hematomas esofágicos como causa de hemorragia digestiva en un caso de golpe de calor

Alterations in blood clotting are a frequent complication of serious heatstroke and may result in gastrointestinal bleeding. We report the case of a 26-year-old man who was admitted to our hospital with symptoms of hyperthermia associated with encephalopathy and disseminated intravascular coagulation (DIC) after prolonged exposure to sunlight. He presented hematemesis, after which he was diagnosed with having a bruising of the esophagus that took up the upper and lower thirds, there being no other lesions in the stomach or duodenum. After supportive treatment and following the resolution of the underlying pathology, the endoscopy-revealed injuries healed with a complete normalization of the esophageal mucosa. Esophageal submucosal bruising is an exceptional cause of hematemesis in serious heatstroke not previously described in the literature.<br>Las alteraciones de la coagulación son una complicación frecuente en el golpe de calor grave, y pueden ser causa de hemorragia digestiva. Presentamos el caso de un varón de 26 años que fue admitido en nuestro hospital por un cuadro de hipertermia, asociado con encefalopatía y coagulación intravascular diseminada tras exposición solar prolongada. Presentó hematemesis por la que fue diagnosticado de múltiples hematomas esofágicos que ocupaban los tercios superior e inferior del órgano, en ausencia de otras lesiones en estómago y duodeno. Tras el tratamiento de soporte y la resolución de la patología subyacente, desaparecieron las lesiones endoscópicas, normalizándose la mucosa esofágica