Controls of primary production in two phytoplankton blooms in the Antarctic Circumpolar Current

The Antarctic Circumpolar Current has a high potential for primary production and carbon sequestration through the biological pump. In the current study, two large-scale blooms observed in 2012 during a cruise with R.V. Polarstern were investigated with respect to phytoplankton standing stocks, primary productivity and nutrient budgets. While net primary productivity was similar in both blooms, chlorophyll a –specific photosynthesis was more efficient in the bloom closer to the island of South Georgia (39 °W, 50 °S) compared to the open ocean bloom further east (12 °W, 51 °S). We did not find evidence for light being the driver of bloom dynamics as chlorophyll standing stocks up to 165 mg m-2 developed despite mixed layers as deep as 90 m. Since the two bloom regions differ in their distance to shelf areas, potential sources of iron vary. Nutrient (nitrate, phosphate, silicate) deficits were similar in both areas despite different bloom ages, but their ratios indicated more pronounced iron limitation at 12 °W compared to 39 °W. While primarily the supply of iron and not the availability of light seemed to control onset and duration of the blooms, higher grazing pressure could have exerted a stronger control toward the declining phase of the blooms

Influence of reaction conditions on the composition of liquid products from two-stage catalytic hydrothermal processing of lignin.

The influence of reaction conditions on the composition of liquid products during two-stage hydrothermal conversion of alkali lignin has been investigated in a batch reactor. Reactions were carried out in the presence of formic acid (FA) and Pt/Al2O3 catalyst. The two different sets of reaction conditions involved alternative reaction times of 1 h and 5 h at 265 °C and 350 °C, respectively. These provided different contributions to reaction severity, which affected the compositions of liquid products. Yields of liquid products reached up to 40 wt% (on lignin feed basis) in the presence of FA under the less severe reaction condition. With 5 h reaction time at 350 °C, alkylphenols, alkylguaiacols and hydrocarbons were the dominant liquid products. However, with 5 h reaction time at 265 °C, phenol and methanol became dominant. The two-stage hydrothermal process led to improved lignin conversion, with the potential to manipulate the liquid product range

Fine-tuning of SIRT1 expression is essential to protect the liver from cholestatic liver disease

Cholestasis comprises aetiologically heterogeneous conditions characterized by accumulation of bile acids in the liver that actively contribute to liver damage. Sirtuin 1 (SIRT1) regulates liver regeneration and bile acid metabolism by modulating farnesoid X receptor (FXR); we here investigate its role in cholestatic liver disease. We determined SIRT1 expression in livers from patients with cholestatic disease, in two experimental models of cholestasis, as well as in human and murine liver cells in response to bile acid loading. SIRT1-overexpressing (SIRT oe ) and hepatocyte-specific SIRT1-KO (knockout) mice (SIRT hep–/– ) were subjected to bile duct ligation (BDL) and were fed with a 0.1% DDC (3,5-diethoxycarbonyl-1,4-dihydrocollidine) diet to determine the biological relevance of SIRT1 during cholestasis. The effect of NorUDCA (24-norursodeoxycholic acid) was tested in BDL/SIRT oe mice. We found that SIRT1 was highly expressed in livers from cholestatic patients, mice after BDL, and Mdr2 knockout mice (Mdr2 –/– ) animals. The detrimental effects of SIRT1 during cholestasis were validated in vivo and in vitro. SIRT oe mice showed exacerbated parenchymal injury whereas SIRT hep–/– mice evidenced a moderate improvement after BDL and 0.1% DDC feeding. Likewise, hepatocytes isolated from SIRT oe mice showed increased apoptosis in response to bile acids, whereas a significant reduction was observed in SIRT hep–/– hepatocytes. Importantly, the decrease, but not complete inhibition, of SIRT1 exerted by norUDCA treatment correlated with pronounced improvement in liver parenchyma in BDL/SIRT oe mice. Interestingly, both SIRT1 overexpression and hepatocyte-specific SIRT1 depletion correlated with inhibition of FXR, whereas modulation of SIRT1 by NorUDCA associated with restored FXR signaling. Conclusion: SIRT1 expression is increased during human and murine cholestasis. Fine-tuning expression of SIRT1 is essential to protect the liver from cholestatic liver damage

Conceptual design of an HTS Canted Cosine Theta dipole magnet for research and hadron therapy accelerators

The European project IFAST's WP8 Innovative Superconducting Magnets aims to develop the technology of Canted Cosine Theta (CCT) magnets wound with High-Temperature Superconductors (HTS). Superconducting magnets could lower the size and cost of synchrotrons and gantries for research and hadron therapy. HTS materials can lead to higher magnetic fields with smaller cryogenic systems than LTS. However, they pose challenges in cable production schemes, magnet design, and cost. The project's final goal is to design a straight CCT-layout magnet with a central dipole field of 4 T, and a ramp rate of 0.4 T/s, but a lower ramp rate of 0.15–0.2 T/s is acceptable for the first step. The paper presents a preliminary design, discussing in particular the protection scheme with the magnet protection solutions for the conductor: one with two and the other with four HTS tapes. Both options generate 4 T of dipole field without an Iron shell, with at least 10 K of margin at an operational temperature of 20 K. To meet the time and budget constraints of the project, a simple cable based on a co-winding of commercial REBCO tapes is proposed. Protection is the most challenging aspect of the design and an adiabatic quench analysis has been used to determine the required thickness of copper stabilizer tapes to mitigate the risk of damaging the magnet during a quench. Finally, the paper evaluates ac and radial current losses during the magnet cycles, discussing the heat distribution and possible solutions for heat extraction.</p

A European Collaboration to Investigate Superconducting Magnets for Next Generation Heavy Ion Therapy

Next generation ion therapy magnets both for gantry and for accelerator (synchrotron) are under investigation in a recently launched European collaboration that, in the frame of the European H2020 HITRIplus and I.FAST programmes, has obtained some funding for work packages on superconducting magnets. Design and technology of superconducting magnets will be developed for ion therapy synchrotron and -especially- gantry, taking as reference beams of 430 MeV/nucleon ions (C-ions) with 1010 ions/pulse. The magnets are about 60–90mmdiameter, 4 to 5 T peak field with a field change of about 0.3 T/s and good field quality. The paper will illustrate the organization of the collaboration and the technical program. Various superconductor options (LTS, MgB2 or HTS) and different magnet shapes, like classical CosTheta or innovative Canted CosTheta (CCT), with curved multifunction (dipole and quadrupole), are under evaluation, CCT being the baseline. These studies should provide design inputs for a new superconducting gantry design for existing facilities and, on a longer time scale, for a brand-new hadron therapy centre to be placed in the South East Europe (SEEIIST project)

A European collaboration to investigate superconducting magnets for next generation heavy ion therapy

Next generation ion therapy magnets both for gantry and for accelerator (synchrotron) are under investigation in a recently launched European collaboration that, in the frame of the European H2020 HITRIplus and I.FAST programmes, has obtained some funding for work packages on superconducting magnets. Design and technology of superconducting magnets will be developed for ion therapy synchrotron and -especially- gantry, taking as reference beams of 430 MeV/nucleon ions (C-ions) with 1010 ions/pulse. The magnets are about 60-90 mm diameter, 4 to 5 T peak field with a field change of about 0.3 T/s and good field quality. The paper will illustrate the organization of the collaboration and the technical program. Various superconductor options (LTS, MgB2 or HTS) and different magnet shapes, like classical CosTheta or innovative Canted CosTheta (CCT), with curved multifunction (dipole and quadrupole), are under evaluation, CCT being the baseline. These studies should provide de-sign inputs for a new superconducting gantry design for existing facilities and, on a longer time scale, for a brand-new hadron therapy center to be placed in the South East Europe (SEEIIST project)

Interaction of contaminated sediment from a salt marsh with estuarine water: evaluation by leaching and ecotoxicity assays and salts from leachate evaporation

Purpose Wastes from a former Portuguese steel plant were deposited between 1961 and 2001 on the riverbank of a tributary of the Tagus River creating a landfill connected to the river, posing a potential contamination risk to the Tagus estuary ecosystem. This study aims to assess the transfer of chemical elements from contaminated sediments to the estuarine water from cycles of sediment leaching so as to evaluate the ecotoxicity of the leachates, and to analyze the solid phases crystallized from those leachates. Materials and methods Landfill sediment and estuarine water samples were collected during low tide. Sediment samples were analyzed for pH, electric conductivity (EC), C-org, NPK, and iron oxides. Leaching assays (four replicates) were done using estuarine water (200 cm(3)/replicate) and 1.5 kg of sediment per reactor. Each reactor was submitted to four leaching processes (0, 28, 49, and 77 days). The sediment was kept moist between leaching processes. Sediment (total (acid digestion) and available fraction (diluted organic acid extraction- Rhizo)) elemental concentrations were determined by inductively coupled plasma-instrumental neutron activation analysis (ICP/INAA). Leachates, and estuarine and sediment pore waters were analyzed for metals/metalloids by ICP/mass spectrometry (MS) and carbonates/sulfate/chloride by standard methodologies. Ecotoxicity assays were performed in leachates and estuarine and pore waters using Artemia franciscana and Brachionus plicatillis. Aliquots of the leachates were evaporated to complete dryness (23-25 degrees C) and crystals analyzed by X-ray powder diffraction (XRD). Results and discussion Sediment with pH=8 and high EC and Corg was contaminated with As, Cd, Cr, Cu, Pb, and Zn. The element concentrations in the available fraction of the sediment were low compared to the sediment total concentrations (<1 % for Rhizo extraction). The concentrations of potentially hazardous elements in the estuarine water were relatively low, except for Cd. Concentrations of hazardous elements in the leachates were very low. Calcium, K, Mg, Na, and chloride concentrations were high but did not vary significantly among the four leaching experiments. Total concentrations of carbonate were much higher in leachates than in estuarine water. Both estuarine water and leachates showed negligible toxicity. Crystals identified in the solids obtained from the leachates by evaporation were halite, anhydrite, epsomite, dolomite, and polyhalite. Conclusions The sediment showed the capacity to retain the majority of the potentially hazardous chemical elements. Remobilization of chemical elements from sediment by leaching was essentially negligible. The variation of total concentrations of Ca, carbonate, and sulfate in leachates indicates that the sediment contained reactive sulfides. Due to its composition, the sediment seems to be a dynamic system of pollution control, which should not be disturbed