228 research outputs found

    Average sedimentary rock rare Earth element patterns and crustal evolution: Some observations and implications from the 3800 Ma ISUA supracrustal belt, West Greenland

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    Rare earth element (REE) data is given on a set of clastic metasediments from the 3800 Ma Isua Supracrustal belt, West Greenland. Each of two units from the same sedimentary sequence has a distinctive REE pattern, but the average of these rocks bears a very strong resemblance to the REE pattern for the North American Shale Composite (NASC), and departs considerably from previous estimates of REE patterns in Archaean sediments. The possibility that the source area for the Isua sediments resembled that of the NASC is regarded as highly unlikely. However, REE patterns like that in the NASC may be produced by sedimentary recycling of material yielding patterns such as are found at Isua. The results lead to the following tentative conclusions: (1) The REE patterns for Isua Seq. B MBG indicate the existence of crustal materials with fractionated REE and negative Eu anomalies at 3800 Ma, (2) The average Seq. B REE pattern resembles that of the North American Shale Composite (NASC), (3) If the Seq. B average is truly representative of its crustal sources, then this early crust could have been extensively differentiated. In this regard, a proper understanding of the NASC pattern, and its relationship to post-Archaean crustal REE reservoirs, is essential, (4) The Isua results may represent a local effect

    A comprehensive study on the microstructure and mechanical properties of arc girth welded joints of spiral welded high strength API X70 steel pipe

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    In the paper, the effect of welding technology on the microstructure and mechanical properties of girth welded joints was presented. Metallographic examinations based on light microscopy and SEM were conducted on girth welded joints of API X70 steel pipe. Research has shown that microstructure of the heat-affected zone (HAZ) of MMA girth welded joints is not homogeneous and depends on the thermal history of each area during the welding process. Near the fusion line the zone is coarse, and further away there is a fine-grained zone. In the area of root passes the microstructure consists of recrystallized ferrite grains unlike to cap passes where the fine bainitic microstructure can be observed. In the case of MAG girth welded joints, the weld microstructure consists of primary austenite grains. The primary austenite boundaries serve as nucleation sites of ferrite. The microstructure of the HAZ varies continuously from a coarse—to fine-grained microstructure of the base material. The results of mechanical properties of girth welded joints are also presented. The hardness and strength of arc welded joints depend on welding filler materials as well as welding technology. The results of hardness distribution of MMA and MAG girth welded joints confirmed the results of microstructural evaluation

    Calmodulin and PF6 are components of a complex that localizes to the C1 microtubule of the flagellar central apparatus

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    Studies of flagellar motility in Chlamydomonas mutants lacking specific central apparatus components have supported the hypothesis that the inherent asymmetry of this structure provides important spatial cues for asymmetric regulation of dynein activity. These studies have also suggested that specific projections associated with the C1 and C2 central tubules make unique contributions to modulating motility; yet, we still do not know the identities of most polypeptides associated with the central tubules. To identify components of the C1a projection, we took an immunoprecipitation approach using antibodies generated against PF6. The pf6 mutant lacks the C1a projection and possesses flagella that only twitch; calcium-induced modulation of dynein activity on specific doublet microtubules is also defective in pf6 axonemes. Our antibodies specifically precipitated five polypeptides in addition to PF6. Using mass spectrometry, we determined the amino acid identities of these five polypeptides. Most notably, the PF6-containing complex includes calmodulin. Using antibodies generated against each precipitated polypeptide, we confirmed that these polypeptides comprise a single complex with PF6, and we identified specific binding partners for each member of the complex. The finding of a calmodulin-containing complex as an asymmetrically assembled component of the central apparatus implicates the central apparatus in calcium modulation of flagellar waveform

    Twice a day accelerated irradiation in postoperative treatment of supratentorial grade III and IV astrocytomas in adults

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    Fourty-seven patients with histologically proven grade III–IV astrocytoma received postoperative accelerated radiotherapy with 2 fractions of 2,65 Gy twice daily, up to total tumor dose of 53 Gy in ten days. The tolerance of the treatment was good, actuarial survival rates at 2, 3 and 5 years were 15%, 9% and 0% respectively

    Quality indicators for measuring the level of patients' involvement in the pharmaceutical care process

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    Patient-centred counseling is an integral part of the pharmaceutical care process. Quality in- dicators can be valuable tools to measure the level of patients’ involvement in their personal healthcare. The aim of the study was to validate two quality indicators for community pharmacy care focusing on patient involvement. As part of the EDQM Pharmaceutical Care Quality Indicators Project (Council of Europe), at least 10 patients per indicator were recruited in each community pharmacy in Serbia and Po- land. Pharmacists targeted patients aged 18-65 years starting chronic treatment (Indicator 1) and elderly patients with polymorbidity receiving at least five chronic treatment medicines (Indicator 2). Based on patients’ answers to a questionnaire, patient-pharmacist consultations took place. For Indicator 2, patients were also offered a medication review. In total, 66% of Serbian patients and 29% Polish patients, for In- dicator 1, were engaged in pharmacist-patient consultations; 96% of Serbian and 84% of Polish elderly patients subsequently participated in medication reviews. Community pharmacists can increase patients’ involvement in their own pharmaceutical care, and there is a need for such services. This study defines a pragmatic approach to encourage/support the implementation of the pharmaceutical care philosophy and working methods in European community pharmacies

    Zirconium-based metal–organic frameworks as acriflavine cargos in the battle against coronaviruses : a theoretical and experimental approach

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    [Image: see text] In this study, we present a complementary approach for obtaining an effective drug, based on acriflavine (ACF) and zirconium-based metal–organic frameworks (MOFs), against SARS-CoV-2. The experimental results showed that acriflavine inhibits the interaction between viral receptor-binding domain (RBD) of spike protein and angiotensin converting enzyme-2 (ACE2) host receptor driving viral cell entry. The prepared ACF@MOF composites exhibited low (MOF-808 and UiO-66) and high (UiO-67 and NU-1000) ACF loadings. The drug release profiles from prepared composites showed different release kinetics depending on the local pore environment. The long-term ACF release with the effective antiviral ACF concentration was observed for all studied ACF@MOF composites. The density functional theory (DFT) calculations allowed us to determine that π–π stacking together with electrostatic interaction plays an important role in acriflavine adsorption and release from ACF@MOF composites. The molecular docking results have shown that acriflavine interacts with several possible binding sites within the RBD and binding site at the RBD/ACE2 interface. The cytotoxicity and ecotoxicity results have confirmed that the prepared ACF@MOF composites may be considered potentially safe for living organisms. The complementary experimental and theoretical results presented in this study have confirmed that the ACF@MOF composites may be considered a potential candidate for the COVID-19 treatment, which makes them good candidates for clinical trials
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