108 research outputs found

    Sedimentary Petrography of Glacial Deposits of the Rotach Valley, Western Allgäu, Southern West Germany

    Get PDF
    Kies-, Schwermineral-, Karbonat- und Korngrößenanalysen würmzeitlicher glazialen Ablagerungen, hauptsächlich Grundmoränen, des Rheintalgletschers im Alpenvorland zeigen, daß verschiedene Faktoren ihre Zusammensetzung beeinflussen. Zum ersten gibt es laterale und vertikale Variationen, welche mit der Aufnahme wechselnder Mengen der lokalen Gesteinstypen oder prä-existierender glazifluvialer Ablagerungen zusammenhängen. Zweitens zeigt sich eine laterale Variation im erratischen Bestandteil, welche die Auswirkung der verschiedenen Gesteinstypen im Ursprungsgebiet der Teilgletscher des Rheintalgletschers und die im Verlauf der Vergletscherung wahrscheinlich wechselnde Lage der Strombahnen der Teilgletscher widerspiegeln.researc

    Synthesis and DNA-binding of Metallocyclic Architectures

    Get PDF
    A new family of cationic N-heterocyclic ligand derivatives was prepared and characterised. Among these compounds are halide salts of the dications [Y(spacer)Y]2+, each of which comprise two N heterocyclic donor groups (Y = 4,4′-bipy, pyz, apyz, apym) linked by a conformationally flexible spacer such as (CH2)n, α,α′-xylylene, 2,6-lutidylene or thiabicyclo[3.3.1]nonane-2,6 diyl. The diquaternary halide salts were converted to NO3- and PF6- salts, and interaction of these bridging ligands with labile palladium(II) and platinum(II) precursors afforded several multinuclear complexes. Bis(4,4′-bipyridinium) dications were incorporated into the dinuclear macrocycles [M2(2,2′ bipy)2{4,4′ bipy(CH2)n4,4′-bipy}2]8+ (M = Pd, Pt; n = 4, 6), cis [Pd2Cl4{4,4′ bipy(CH2)34,4′-bipy}2]4+, [Pt2(dppp)2{4,4′-bipy(1,2-xylylene)4,4′-bipy}2]8+ and cis-[Pt2Cl4{4,4′-bipy(1,2-xylylene)4,4′-bipy}2]4+. While bis(pyrazinium) analogues were unreactive towards the palladium(II) and platinum(II) precursors, the doubly deprotonated bis(3 aminopyrazinium) and bis(2 aminopyrimidinium) derivatives served as charge-neutral quadruply-bridging ligands in the complexes [Pt4(2,2′ bipy)4{apyz(CH2)6apyz–2H}2]8+ and [Pt4(2,2′ bipy)4{apym(CH2)5apym–2H}2]8+, both of which feature Pt(II). Pt(II) interactions. Larger species formed when the diamine O,O′-bis(2-aminoethyl)octadeca(ethylene glycol) (PEGda) was treated with cis dinitratopalladium(II) and platinum(II) precursors. The resulting complexes [M(N,N)(PEGda)]2+ (M = Pd, Pt; N,N = 2,2′-bipy, en, tmeda) possessed great size (62 membered chelate rings) and aqueous solubility. DNA-binding studies were conducted with selected complexes in order to investigate the types of interactions these species might participate in. Equimolar mixtures containing either the 16mer duplex DNA D2 or the single strand D2a and palladium(II)/platinum(II) complexes were prepared and analysed by negative-ion ESI MS. Studies of D2/Pd(II) mixtures suggested extensive fragmentation was occuring, and the use of [Pd(tmeda)(PEGda)]2+ and [Pd2(2,2′-bipy)2{4,4′-bipy(CH2)44,4′-bipy}2]8+ resulted in D2 adducts of [Pd(tmeda)]2+ and [4,4′-bipy(CH2)44,4′-bipy]2+, respectively. Decomposition also occurred when D2a was used, although 1 : 1 adducts were observed with [Pd(tmeda)(PEGda)]2+, [Pd(2,2′ bipy)(PEGda)]2+ and [Pd2(2,2′-bipy)2{4,4′-bipy(CH2)44,4′-bipy}2]8+. The low intensities of these adducts indicated that they are unstable towards ESI MS. Analogous ESI-MS experiments using platinum(II) derivatives were performed and, in contrast to those with palladium(II), indicated that the complexes remained largely intact. ESI-MS analysis of D2/Pt(II) mixtures allowed for the detection of 1 : 1 D2 adducts of [Pt(en)(PEGda)]2+, [Pt(tmeda)(PEGda)]2+ and [Pt2(2,2′-bipy)2{4,4′-bipy(CH2)44,4′-bipy}2]8+. Intensities of the adduct ions suggested the greater charge and aryl surface area allow the dinuclear species to bind D2 most strongly. Both [Pt(2,2′-bipy)(Mebipy)2]4+ and [Pt(2,2′ bipy)(NH3)2]2+ gave rise to 1 : 2 adducts of D2, although the latter was found to be a weaker binder, perhaps owing to its lower charge. Data obtained using 1 : 5 (D2 : complex) mixtures were consistent with the results above and suggested that D2 can bind more molecules of daunomycin than any of the platinum(II) species. Analyses of D2a/Pt(II) mixtures gave results similar to those obtained with D2, although fragmentation was more pronounced, indicating that the nucleobases in D2a play more significant roles in mediating decomposition than those in D2, in which they are paired in a complementary manner. Investigations into the effects of selected platinum(II) complexes on the thermal denaturation of calf-thymus DNA (CT-DNA) in solution were conducted. Both [Pt2(2,2′ bipy)2{4,4′-bipy(CH2)64,4′-bipy}2]8+ and [Pt(2,2′-bipy)(Mebipy)2]4+ greatly stabilised CT-DNA, most likely by intercalation. In contrast, [Pt(tmeda)(PEGda)]2+ and [Pt(en)(PEGda)]2+ (as well as PEGda) caused negligible changes in melting temperature (∆Tm), suggesting that these interact weakly with CT-DNA. Data for [Pt(2,2′ bipy)(PEGda)]2+ and [Pt(2,2′-bipy)(NH3)2]2+ indicated that these species perhaps intercalate CT-DNA, with similar ∆Tm values for both complexes implying that PEGda does not play a major role in binding. While findings from ESI-MS experiments were similar to those from the thermal denaturation experiments, discrepancies between results from the two methods could be found. In particular, fragmentation of cyclic species during ESI-MS caused the binding strength of the species to be underestimated when this method was employed

    A continent-wide framework for local and regional stratigraphies

    Get PDF
    This study is part of an interdisciplinary project dealing with the Palaeolithic occupation phases of northern Europe. In order to give feedback on the time control over the scattered Palaeolithic evidence, the thesis is focused on the (chrono)stratigraphy of the terrestrial Middle Pleistocene succession, spanning the period from approximately 780,000 to 130,000 years ago. Its record, including the Palaeolithic archeological record, is fragmentary and heterogeneous both in time and space. Interpretation of a chronological sequence from sedimentary units into glacials and interglacials has never been documented in a satisfactory way. Different approaches supplementary to the traditional climatostratigraphical procedure have been assessed. Local multidisciplinary data from the type regions in Northwest and Central Europe has been integrated into a large-scale framework using unconformity-bounded and genetic sequence stratigraphical principles. From the genetic depositional sequences within this framework palaeoclimatic events have been interpreted comprising reflections of climate-forcing of different origin, type and scale order. They are arranged into a relative chronology on the basis of superposition, correlation of unconformity-bounded and biostratigraphical markers and independent dates. In the synthesis, the widespread terrestrial sequences and events have been matched with the marine isotope stages (MIS). At least two lower boundary levels can be placed at relevant MIS-transitions: - the lower boundary of the late Middle Pleistocene corresponding to the deglaciation interval of MIS 12/11 at about 400,000 years ago, representing the transition of the Elsterian cold Stage to the Holsteinian warm Stage - a boundary level corresponding to the deglaciation of MIS 16/15 at about 600,000 years ago, subdividing the Cromerian part of the early Middle Pleistocene into a part A and a part B. From the stratigraphical analysis in this thesis it is concluded that the lower boundary of Palaeolithic occupation in the study area has to be set at about 600,000 years ago.LEI Universiteit LeidenNederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)Human Origin

    Exploring views on medical care for people with intellectual disabilities: an international concept mapping study

    Get PDF
    Contains fulltext : 253060.pdf (Publisher’s version ) (Open Access

    Treatment of patch infection after carotid endarterectomy:a systematic review

    Get PDF
    Carotid endarterectomy (CEA) with patch angioplasty is a widely used method for treating carotid artery stenosis. Patch infections are extremely rare, but the consequences may be serious. The current gold standard for treatment is patch excision and reconstruction with autologous material. However, no consensus has been reached and other options may be valuable as well in certain cases. The objective of this study was to evaluate the various treatment options for carotid patch infection after CEA with patch angioplasty on the basis of their outcomes (reinfection, ischemic stroke, and infection-related mortality). This systematic review was conducted in accordance with the PRISMA statement. The electronic bibliographic databases PubMed, Cochrane, and EMBASE were searched. Case series and case reports were included. Studies in languages other than English were excluded. Patients who developed a post-operative patch infection of CEA with patch angioplasty were included. Angioplasty could be performed with any type of patch. Patch infection needed to be confirmed by clinical presentation in combination with imaging, culture, or during the operation. The primary outcome measures were reinfection, ischemic stroke, and infection-related mortality. Eleven retrospective case series, two prospective case series, and seventeen case reports were included. The study size was 165 patients (mean age 69.7 years, M/F ratio 1.75:1). One hundred and seventy-one patches developed a patch infection after CEA with patch angioplasty and needed treatment. Treatment strategies included conservative treatment (14.0%), endovascular treatment (4.7%), and open surgery (81.4%). Mean follow-up was 34.8 months and extended up to 180 months. Reinfection rate was 4.7%, ischemic stroke rate 5.8%, and infection-related mortality rate 2.3%. No statistical comparison between treatment options could be performed, because of the heterogeneity of the included studies. Autologous material should be the primary choice of treatment if patch infection is diagnosed after CEA with patch angioplasty. In emergency situations, endovascular treatment, carotid ligation, or abscess drainage could be considered. Endovascular treatment and abscess drainage are temporary solutions. After the patient has recovered sufficiently, a more durable treatment i.e., open surgery is advised. Endo vacuum assisted closure (EndoVAC) seems to be promising. Further research is needed to determine the applicability of each treatment option.</p

    Associations between Dietary Fiber Intake in Infancy and Cardiometabolic Health at School Age: The Generation R Study

    Get PDF
    Dietary fiber (DF) intake may be beneficial for cardiometabolic health. However, whether this already occurs in early childhood is unclear. We investigated associations between DF intake in infancy and cardiometabolic health in childhood among 2032 children participating in a population-based cohort in The Netherlands. Information on DF intake at a median age of 12.9 months was collected using a food-frequency questionnaire. DF was adjusted for energy intake using the residual method. At age 6 years, body fat percentage, high-density lipoprotein (HDL)-cholesterol, insulin, triglycerides, and blood pressure were assessed and expressed in age- and sex-specific standard deviation scores (SDS). These five factors were combined into a cardiometabolic risk factor score. In models adjusted for several parental and child cova

    Microstructures in subglacial and proglacial sediments : understanding faults, folds and fabrics, and the influence of water on the style of deformation

    Get PDF
    Macroscopic field and micromorphological studies have been carried out on subglacially and proglacially deformed glacigenic sequences at a number of sites throughout Scotland, UK. Examination of microstructures (folds, faults, hydrofractures, plasmic fabrics) aided understanding of the deformation histories preserved in the sediments, but a similar range of structures were developed in both subglacial and proglacial settings. Discrimination between subglacial and proglacial deformation was only possible when micromorphological data was used in conjunction with larger-scale field observations. Variations in lithology and water content were controlling factors influencing the style and apparent intensity of deformation recorded. Changes in pore-water content and pressure during deformation can lead to liquefaction and hydrofracturing, with early formed structures locally controlling the pattern of water-escape. Liquefaction can also lead to homogenisation of the sediments and the destruction of earlier deformation structures, even at relatively low strains. Beds or zones of liquefied sand and silt may form highly ‘lubricated’ detachments within the sediment pile, resulting in a marked reduction in the amount of shear transmitted to underlying units. A multidisciplinary approach, involving sedimentological, geomorphological, stratigraphical and structural field observations, combined with micromorphological analysis, is recommended to confidently unravel the glacitectonic history and depositional environment of most deformed glacigenic sedimentary sequences

    Minutes of the Classis of Nieuwlevsen

    Get PDF
    Minutes of the Classis of Nieuwlevsen.https://digitalcommons.hope.edu/vrp_1830s/1104/thumbnail.jp

    Mid-Pleistocene thin-skinned glaciotectonic thrusting of the Aberdeen Ground Formation, Central Graben region, central North Sea

    Get PDF
    This paper presents the results of a high-resolution 2D seismic survey of mid-Pleistocene glaciogenic sediments in the Central Graben region of the central North Sea. Sediments have undergone major glaciotectonic thrusting and folding associated with the repeated southerly advance of a mid-Pleistocene ice sheet. The total observed length of the thrust-stacked section is approximately 5–6 km, comprising a series of discrete thrust slices, which range in length from  700 m. The basal detachment of the thrust complex occurs at a depth of ca. 220 m below the sea bed within the upper Aberdeen Ground Formation. A thin-skinned glaciotectonic model involving proglacial to ice-marginal glaciotectonic thrusting followed by post-tectonic deposition is proposed. Initial ice advance led to the over-pressurizing of groundwater within a laterally extensive sand sheet in the upper Aberdeen Ground Formation, promoting the formation of a major décollement surface at the base of the developing thrust-stack. Over-pressurization of the groundwater system is thought to have occurred in response to rapid ice advance, suggesting that the development of large-scale thrust complexes may be associated with surge-type behaviour. The proposed model evidences complex dynamics of mid-Pleistocene ice sheets within the central North Sea
    • …
    corecore