3,883 research outputs found

    Archaeological and archaeometric study of the glass finds from the ancient harbour of Classe (Ravenna- Italy): new evidence

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    Introduction: The present study focuses on Late-Roman/Early Medieval glass found in the productive area within the ancient harbour of Classe near Ravenna, one of the most important trade centres between the 5th and 8th centuries AD of the Northern Adriatic area. Aims of the study were the identification of the main glass compositions and their contextualisation in Late-Antique groups; the identification of provenance of raw glass, and, consequently, of commercial routes; the extent, if any, of recycling glass cullet, as an alternative to the import of fresh raw glass; the identification of possible connections between archaeological typology and glass chemical composition. Results: 32 glassworking wastes and 25 drinking vessel fragments for a total amount of 57 fragments were devoted to chemical analysis in XRF and EPMA. All the analysed fragments are silica-soda lime glasses, produced with natron as a flux, and are compositionally similar to Late-Antique groups HIMT, S\ue9rie 3.2 and Levantine1. Raw glass chunks, glassworking wastes and objects of comparable compositions are identified into HIMT and S\ue9rie 3.2 groups, while the Levantine 1 group includes only objects and glassworking wastes. Systematic comparisons between Classe and Aquileia, the two most important Late-Antique archaeological sites of North-Eastern Italy, were also carried out, and the same compositional groups were identified, although S\ue9rie 3.2 in the Classe assemblage is more represented. Sr and Nd isotopic analysis confirmed that the composition of the three glasses derive from coastal sands of the Syro-Palestinian and Egyptian shore, with a slight shift in comparison to the published data. Little evidence of recycling was identified in the assemblage. Conclusions: In the 5th century, a secondary glass workshop devoted to the shaping of glass vessels starting from raw glass chunks and, possibly, glass cullet, was active in the area of the harbour. Raw glass of HIMT and S\ue9rie 3.2 was imported from the Levant and Egypt. Comparisons between Classe and Aquileia show that during the Late Antiquity these sites seem to be supplied of raw glass by the same trade routes. In addition, some connections between types and chemical compositions were highlighted

    Microparticles Produced by the Hydrogel Template Method for Sustained Drug Delivery

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    Polymeric microparticles have been used widely for sustained drug delivery. Current methods of microparticle production can be improved by making homogeneous particles in size and shape, increasing the drug loading, and controlling the initial burst release. In the current study, the hydrogel template method was used to produce homogeneous poly(lactide-co-glycolide) (PLGA) microparticles and to examine formulation and process-related parameters. Poly(vinyl alcohol) (PVA) was used to make hydrogel templates. The parameters examined include PVA molecular weight, type of PLGA (as characterized by lactide content, inherent viscosity), polymer concentration, drug concentration and composition of solvent system. Three model compounds studied were risperidone, methylprednisolone acetate and paclitaxel. The ability of the hydrogel template method to produce microparticles with good conformity to template was dependent on molecular weight of PVA and viscosity of the PLGA solution. Drug loading and encapsulation efficiency were found to be influenced by PLGA lactide content, polymer concentration and composition of the solvent system. The drug loading and encapsulation efficiency were 28.7% and 82% for risperidone, 31.5% and 90% for methylprednisolone acetate, and 32.2 % and 92 % for paclitaxel, respectively. For all three drugs, release was sustained for weeks, and the in vitro release profile of risperidone was comparable to that of microparticles prepared using the conventional emulsion method. The hydrogel template method provides a new approach of manipulating microparticles

    Pathophysiologisch-serologische, bildgebende und klinische Charakteristika der Neuromyelitis Optica

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    Hintergrund: Neuromyelitis optica-Spektrum-Erkrankungen (NMOSD) stellen eine Gruppe neuroinflammatorischer Erkrankungen dar, die mit dem klinischen Auftreten von Myelitiden und/oder Optikusneuritiden (ON) einhergeht. Aufgrund zahlreicher überlappender klinischer und paraklinischer Eigenschaften beim Nachweis verschiedener Antikörper, vor allem auch in Abgrenzung zur Multiplen Sklerose (MS), besteht weiterhin der Bedarf nach neuen Biomarkern. Methodik: In zwei Studien wurden NMOSD-Patienten mit positivem Nachweis für Aquaporin-4-Antikörper (AQP-4-Ak) mittels 7 Tesla (T) Magnetresonanztomografie (MRT) hinsichtlich der I) periventrikulären Venendichte (PVA) in T2*-gewichteten Aufnahmen und II) der Phasenverschiebung in suszeptibilitätsgewichteten Sequenzen untersucht. Als Vergleich dienten die Ergebnisse von Patienten mit MS und gesunden Kontrollen (HC). In einer dritten Arbeit (III) erfolgte eine retrospektive Auswertung visueller Parameter im Vergleich von AQP-4-Ak-positiven Patienten und Patienten mit Antikörpern gegen das Myelin-Oligodendrozyten-Glykoprotein (MOG) mittels Optischer Kohärenztomografie (OCT), Visuell Evozierter Potenziale (VEP) und der Fernvisus-Messung. Ergebnisse: Bildmorphologisch zeigte sich in den 7T-T2* gewichteten Aufnahmen bei Patienten mit AQP-4-Ak-positiver NMOSD eine normal große PVA (AQP-4-Ak: PVA = 133 mm2; MS: PVA = 117 mm2; HC: PVA =144 mm2) und überwiegend fehlende paramagnetische Phasenverschiebungen (107 von 112 Läsionen, 96%) in den SWI-Sequenzen. Hinsichtlich des Vergleichs von MOG-Ak- gegenüber von AQP4-Ak-positiven Patienten fiel eine größere absolute Schubrate (Mittelwert, Spannweite, MOG-Ak: 4.5, 1 - 13; APQ4-Ak: 2, 1 -4; p = 0.012), bei insgesamt ähnlichem Verlust der im OCT gemessenen peripapillären retinalen Nervenfaserschicht (pRNFL) der AQP-4-Ak-positiven NMOSD im Vergleich zu den MOG-Ak-positiven Patienten auf (Mittelwert Standardabweichung, MOG-Ak: 59 ± 23 µm, AQP-4-Ak: 59 ± 21 µm). Jedoch waren die Werte der pRNFL nach dem Erstereignis einer ON bei den Patienten mit AQP-4-Ak deutlich stärker reduziert, als bei den MOG-Ak-positiven Patienten (AQP-4-Ak: pRNFL-Verlust = 32.8 μm (p<0.001); MOG-Ak: pRNFL-Verlust = 12.8 μm (p=0.001)). Schlussfolgerung: Mit Hilfe von modernen diagnostischen Verfahren, wie dem Ultrahochfeld-MRT und dem OCT wird die bessere Charakterisierung von phänotypisch ähnlichen neuroinflammatorischen Krankheitsentitäten ermöglicht. Die hierfür zugrundeliegenden unterschiedlichen Pathomechanismen sind bisher nicht vollständig verstanden und bedürfen weiterer Untersuchungen.Introduction: Different neuroinflammatory entities define the group of Neuromyelitis optica spectrum disorders (NMOSD) and are usually associated with the presentation of myelitis and/or optic neuritis. Although various antibodies were verified, there is still the challenge of overlapping clinical and paraclinical phenotypes which ask for further new diagnostic parameters. Methods: By using 7 Tesla (T) magnetic resonance imaging (MRI) patients with aquaporin-4-antibodies (AQP-4-ab) were investigated concerning a) the periventricular venous area (PVA) at T2*-weighted images and b) the phase changes within brain lesions at susceptibility-weighted (SWI)-images. The findings were compared to patients with Multiple Sclerosis (MS) and healthy controls (HC). Further patients with AQP-4-ab and antibodies against myelin oligodendrocyte glycoprotein (MOG-ab) were faced by using retrospective data of retinal optical coherence tomography (OCT), visual acuity and visual evoked potentials (VEP). Results: Patients with AQP-4-ab presented equal results like HC concerning the PVA (AQP-4-ab: PVA = 133 mm2; MS: PVA = 117 mm2; HC: PVA =144 mm2) and predominantly missing phase changes in brain lesions at SWI-images (107 of 112 lesions, 96%). Both, AQP-4-ab- and MOGab-positive patients, presented a loss in peripapillary nerve fiber layer (pRNFL) thickness at the same extend (mean ± standard deviation, MOG-ab: 59 ± 23 ±m, AQP4-ab: 59 ± 21 ±m), while the number of episodes of optic neuritis (ON) was lower in AQP4-ab-positive patients (mean, range, MOG-ab: 4.5, 1 - 13; APQ4-ab: 2, 1 -4; p = 0.012). However, the loss of pRNFL thickness after the first episode of ON was greater in patients with AQP-4-ab (AQP-4-ab: pRNFL-loss = 32.8 µm (p<0.001); MOG-ab pRNFL-loss = 12.8 µm (p=0.001). Conclusion: With the help of novel diagnostic tools, like the ultrahighfield-MRI and OCT, it is possible to distinguish between neuroinflammatory entities with similar phenotypes. For a better understanding of the underlying pathomechanisms further investigations are still needed

    Wood-Inspired Morphologically Tunable Aligned Hydrogel for High-Performance Flexible All-Solid-State Supercapacitors

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    Oriented microstructures are widely found in various biological systems for multiple functions. Such anisotropic structures provide low tortuosity and sufficient surface area, desirable for the design of high-performance energy storage devices. Despite significant efforts to develop supercapacitors with aligned morphology, challenges remain due to the predefined pore sizes, limited mechanical flexibility, and low mass loading. Herein, a wood-inspired flexible all-solid-state hydrogel supercapacitor is demonstrated by morphologically tuning the aligned hydrogel matrix toward high electrode-materials loading and high areal capacitance. The highly aligned matrix exhibits broad morphological tunability (47–12 µm), mechanical flexibility (0°–180° bending), and uniform polypyrrole loading up to 7 mm thick matrix. After being assembled into a solid-state supercapacitor, the areal capacitance reaches 831 mF cm−2 for the 12 µm matrix, which is 259% times of the 47 µm matrix and 403% times of nonaligned matrix. The supercapacitor also exhibits a high energy density of 73.8 µWh cm−2, power density of 4960 µW cm−2, capacitance retention of 86.5% after 1000 cycles, and bending stability of 95% after 5000 cycles. The principle to structurally design the oriented matrices for high electrode material loading opens up the possibility for advanced energy storage applications

    Materials for Diabetes Therapeutics

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    This review is focused on the materials and methods used to fabricate closed-loop systems for type 1 diabetes therapy. Herein, we give a brief overview of current methods used for patient care and discuss two types of possible treatments and the materials used for these therapies–(i) artificial pancreases, comprised of insulin producing cells embedded in a polymeric biomaterial, and (ii) totally synthetic pancreases formulated by integrating continuous glucose monitors with controlled insulin release through degradable polymers and glucose-responsive polymer systems. Both the artificial and the completely synthetic pancreas have two major design requirements: the device must be both biocompatible and be permeable to small molecules and proteins, such as insulin. Several polymers and fabrication methods of artificial pancreases are discussed: microencapsulation, conformal coatings, and planar sheets. We also review the two components of a completely synthetic pancreas. Several types of glucose sensing systems (including materials used for electrochemical, optical, and chemical sensing platforms) are discussed, in addition to various polymer-based release systems (including ethylene-vinyl acetate, polyanhydrides, and phenylboronic acid containing hydrogels).Juvenile Diabetes Research Foundation International (17-2007-1063)Leona M. and Harry B. Helmsley Charitable Trust (09PG-T1D027)United States. National Institutes of Health (F32 EB011580-01

    Investigation of the catalytic performance of Pd/CNFs for hydrogen evolution from additive-free formic acid decomposition

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    In recent years, research efforts have focused on the development of safe and efficient H2 generation/storage materials toward a fuel-cell-based H2 economy as a long-term solution in the near future. Herein, we report the development of Pd nanoparticles supported on carbon nanofibers (CNFs) via sol-immobilisation and impregnation techniques. Thorough characterisation has been carried out by means of XRD, XPS, SEM-EDX, TEM, and BET. The catalysts have been evaluated for the catalytic decomposition of formic acid (HCOOH), which has been identified as a safe and convenient H2 carrier under mild conditions. The influence of preparation method was investigated and catalysts prepared by the sol-immobilisation method showed higher catalytic performance (PdSI/CNF) than their analogues prepared by the impregnation method (PdIMP/CNF). A high turnover frequency (TOF) of 979 h−1 for PdSI/CNF and high selectivity (>99.99%) was obtained at 30 °C for the additive-free formic acid decomposition. Comparison with a Pd/AC (activated charcoal) catalyst synthesised with sol-immobilisation method using as a support activated charcoal (AC) showed an increase of catalytic activity by a factor of four, demonstrating the improved performance by choosing CNFs as the preferred choice of support for the deposition of preformed colloidal Pd nanoparticles

    Mechanisms of deterioration of nutrients

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    Methods for improving the quality of freeze-dried foods were investigated. Areas discussed include: (1) microstructure of freeze-dried systems, (2) structural changes in freeze-dried systems, (3) artificial food matrices, and (4) osmotic preconcentration to yield improved freeze-dried products
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