3,127 research outputs found

    A search for magnetic fields on central stars in planetary nebulae

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    One of the possible mechanisms responsible for the panoply of shapes in planetary nebulae is the presence of magnetic fields that drive the ejection of ionized material during the proto-planetary nebula phase. Therefore, detecting magnetic fields in such objects is of key importance for understanding their dynamics. Still, magnetic fields have not been detected using polarimetry in the central stars of planetary nebulae. Circularly polarized light spectra have been obtained with the Focal Reducer and Low Dispersion Spectrograph at the Very Large Telescope of the European Southern Observatory and the Intermediate dispersion Spectrograph and Imaging System at the William Herschel Telescope. Nineteen planetary nebulae spanning very different morphology and evolutionary stages have been selected. Most of central stars have been observed at different rotation phases to point out evidence of magnetic variability. In this paper, we present the result of two observational campaigns aimed to detect and measure the magnetic field in the central stars of planetary nebulae on the basis of low resolution spectropolarimetry. In the limit of the adopted method, we can state that large scale fields of kG order are not hosted on the central star of planetary nebulae.Comment: Paper accepted to be published in Astronomy and Astrophysics on 20/01/201

    Cellular Variant of Focal Segmental Glomerulosclerosis Treated with Plasma Exchange

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    Focal segmental glomerulosclerosis (FSGS) is the most common primary glomerular disease in nephrotic patients in the United States, frequently leading to end stage renal disease (ESRD). The cellular variant is a rare form of FSGS commonly associated with poor outcome. We report a case of cellular variant FSGS with progressive kidney dysfunction successfully treated with plasma exchange (PE). A 49-year-old Caucasian female presented with two days of ankle edema and hypertension. Laboratory findings showed serum creatinine (SCr) 1.6 mg/dL, urine albumin/creatinine ratio (uACR) 2.8 g/g, haematuria 3+ and no immunological abnormalities. Kidney biopsy revealed a cellular FSGS variant with segmental endocapillary proliferation on light microscopic, negative immunofluorescence and widespread foot process effacement by electronic microscopic. Prednisolone 1 mg/Kg was started. Four days later the SCr worsened (3.6 mg/dL) and the patient became severely nephrotic with uACR of6.8g/g, quickly attaining a maximum of 24.6 g/g in a short time and albumin of 2.15g/dL. Pulsed methyl prednisolone was started. Despite a 10 course of steroids, no clinical improvement was observed. Considering the rapidly worsening renal function and severe nephrotic syndrome, PE was begun in association with mycophenolate mofetil and tacrolimus. Kidney function recovered after one week. Complete remission was achieved at 3rd week and remains in complete remission at 27 months follow-up. Prolonged remission is a challenge in primary FSGS. PE associated with combined immunosuppression was effective in the present case. The short and long-term effects of plasma exchange in primary FSGS should be evaluated in prospective studies.info:eu-repo/semantics/publishedVersio

    Kidney biopsy in Lupus Nephritis: still essential in clinical practice

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    Renal involvement in Systemic Lupus Erythematous is common and its management remains a daily challenge for clinical providers. Percutaneous kidney biopsy remains the gold standard for diagnosis of lupus nephritis. More recently, we have seen the role of the biopsy being challenged, considering the widespread use of corticosteroids and mycophenolate mofetil for all forms of lupus nephritis. We present a review of published evidence regarding first and repeat kidney biopsies for patients with lupus nephritis. Based on the available literature, we recommend a kidney biopsy to guide treatment and determine prognosis and we also suggest an algorithm for kidney rebiopsy in lupus nephritis.info:eu-repo/semantics/publishedVersio

    European marine aggregates resources: Origins, usage, prospecting and dredging techniques

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    Marine aggregates (sand and gravel) are important mineral resources and traded commodities. Their significance is bound to increase further, due to increasing coastal zone development, stricter environmental regulation concerning land-won aggregates and increasing demand for beach replenishment material. Marine aggregate (MA) deposits can be differentiated into relict and modern deposits. The former consist of sedimentary material deposited in the past and under different environmental and sedimentary regimes than those existing presently (e.g. the gravel/ sand deposits of the Pleistocene buried river valleys of the northwestern European shelves). The latter are deposits, which have been formed and controlled by the modern hydro-and sediment dynamic conditions (e.g. the linear sand banks of the southern North Sea). The present contribution reviews the current state of affairs in 9 representative European Member States concerning the prospecting and extraction (dredging) techniques as well as the levels of production and usage. The review has shown a mixed record as, in some of the studied States, marine aggregate production is an important and streamlined activity, whereas other States have not yet developed efficient marine aggregate policies and industries. It has also shown that although attempts have been lately made to coordinate the field, the industry still faces problems, which hinder its sustainable development. These include (amongst others): lack of standardisation of the relevant information, difficulties in the access to information, non-coherent regulatory regimes and limited collaboration/coordination between the marine scientific research establishments and the marine aggregate industry. These issues should be addressed as quickly as possible in order to exploit effectively this important mineral resource

    New active antioxidant multilayer food packaging films containing Algerian Sage and Bay leaves extracts and their application for oxidative stability of fried potatoes

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    The antioxidant activity of Sage leaf (SL) and Bay leaf (BL) extracts was studied. Both plants were extracted using water and ethanol at different concentration, and the antioxidant activity was measured by ABTS [2, 2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid)] radical cation scavenging and reducing power (RP) methods. In both cases 60% and 80% ethanolic extracts of Sage and Bay leaves showed the highest activity and were incorporated into multilayer films. The initial concentration for 60% ethanolic extracts of Sage and Bay leaves to scavenge 50% of free radical ABTS were 5.67 ± 0.26 µg × mL-1 and 18.68 ± 0.16 µg × mL-1 respectively, whereas for 80% ethanolic extracts the concentrations were 7.96 ± 0.02 and 14.65 ± 0.59 µg × mL-1 respectively. The initial concentrations of ethanolic 60% extracts of Sage and Bay leaves to allow absorbance 0.5 for reducing power were 35.38 ± 0.19 µg × mL-1 and 91.43 ± 2.84 µg × mL-1 respectively, while for 80% ethanolic extracts of Bay and Sage leaves were 46.01 ± 1.21 µg × mL-1 and 85.47 ± 0.9 µg × mL-1 respectively. Then, the multilayer films were exposed to a gas stream enriched with free radicals to evaluate the free radicals scavenging. The new packaging with 60% ethanolic Sage extract exhibited the highest activity with low percentage of hydroxylation (69.64 ± 6.86%) followed by that with 80% ethanolic extract for both Bay (85.49 ± 5.3%) and Sage (87.09 ± 3.93%) leaves extracts. The ability of two active packaging built with 60% ethanolic Sage extract and 80% ethanolic Bay extract to inhibit lipid oxidation of fried potatoes was studied by measuring secondary lipid oxidation products using thiobarituric acid reactive substances (TBARS). Significant lower value of Malondialdehyde (MDA) was obtained for fried potatoes stored in active packaging built with ethanolic 60% extract of Sage and 80% ethanolic extract of Bay leaves (0.342 ± 0.01 and 0.392 ± 0.02 µg MDA × g-1 respectively) at 40 °C for 20 days compared to the control (0.568 ± 0.03 µg MDA × g-1). Lipid oxidation decreased 40% and 31% for packaging with 60% Sage and 80% Bay ethanolic extracts respectively. The UPLC–MS–QTOF analysis of Sage and Bay leaves extracts revealed the presence of phenolic acids, tannins, flavonoids, and terpenoids. Migration tests from active materials demonstrated the absence of migration
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