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The ITER neutral beam system will be equipped with radio-frequency (RF) negative ion sources, based on the IPP Garching prototype source design. Up to 100 kW at 1 MHz is coupled to the RF driver, out of which the plasma expands into the main source chamber. Compared to arc driven sources, RF sources are maintenance free and without evaporation of tungsten. The modularity of the driver concept permits to supply large source volumes. The prototype source (one driver) demonstrated operation in hydrogen and deuterium up to one hour with ITER relevant parameters. The ELISE test facility is operating with a source of half the ITER size (four drivers) in order to validate the modular source concept and to gain early operational experience at ITER relevant dimensions. A large variety of diagnostics allows improving the understanding of the relevant physics and its link to the source performance. Most of the negative ions are produced on a caesiated surface by conversion of hydrogen atoms. Cs conditioning and distribution have been optimized in order to achieve high ion currents which are stable in time. A magnetic filter field is needed to reduce the electron temperature and co-extracted electron current. The influence of different field topologies and strengths on the source performance, plasma and beam properties is being investigated. The results achieved in short pulse operation are close to or even exceed the ITER requirements with respect to the extracted ion currents. However, the extracted negative ion current for long pulse operation (up to 1 h) is limited by the increase of the co-extracted electron current, especially in deuterium operation.

This study aimed to immobilize trypsin on activated carbon submitted to different surface modifications and its application in casein hydrolysis. With the aim of determining which support can promote better maintenance of the immobilized enzyme. Results showed that pH 5.0 was obtained as optimal for immobilization and pH 9.0 for the casein hydrolysis reaction for activated carbon and glutaraldehyde functionalized carbon. Among the supports used, activated carbon modified with iron ions in the presence of a chelating agent was the one that showed best results, under the conditions evaluated in this study. Presenting an immobilization yield of 95.15% and a hydrolytic activity of 4.11 U, same as soluble enzyme (3.76 U). This derivative kept its activity stable at temperatures above 40 °C for1 h and when stored for 30 days at 5 °C. Furthermore, it was effective for more than 6 reuse cycles (under the same conditions as the 1st cycle). In general, immobilization of trypsin on metallized activated carbon can be an alternative to biocatalysis, highlighting the advantages of protease immobilization.

This article studies a multi-item auction characterized by asymmetric bidders and quantity discounts. We report a practical application of this type of auction in the procurement of Internet services to the 709 public schools of Buenos Aires. The asymmetry in this application is due to firms’ existing technology infrastructures, which affect their ability to provide the service in certain areas of the city. A single round first-price sealed-bid auction, it required each participating firm to bid a supply curve specifying a price on predetermined graduated quantity intervals and to identify the individual schools it would supply. The maximal intersections of the sets of schools each participant has bid on define regions we call competition units. A single unit price must be quoted for all schools supplied within the same quantity interval, so that firms cannot bid a high price where competition is weak and a lower one where it is strong. Quantity discounts are allowed so that the bids can reflect returns-to-scale of the suppliers and the auctioneer may benefit of awarding bundles of units instead of separate units. The winner determination problem in this auction poses a challenge to the auctioneer. We present an exponential formulation and a polynomial formulation for this problem, both based on integer linear programming. The polynomial formulation proves to find the optimal set of bids in a matter of seconds. Results of the real-world implementation are reported.

Northern China has been identified as an independent centre of domestication for various types of millet and other plant species, but tracing the earliest evidence for the exploitation of wild cereals and thus the actual domestication process has proven challenging. Evidence from microscopic analyses of stone tools, including use-wear, starch and phytolith analyses, however, show that in the Shizitan region of north China, various plants have been exploited as far back as 28000 years ago, and wild millets have been harvested and processed by the time of the Last Glacial Maximum, 24000 years ago. This is some 18000–14000 years before the earliest evidence for domesticated millet in this region.

A study was carried out on the immobilization of pepsin in activated carbon functionalized by different techniques (glutaraldehyde, genipin, and metallization) aiming at its application in obtaining bioactive peptides through casein hydrolysis. Studies of the immobilized derivatives were carried out in addition to the evaluation of the antioxidant potential of the peptides. Among the pH range studied, pH 3.0 was selected due to the higher activity of the derivatives at this pH. The support modification by metallization was the method with the best results, providing a 121% increase in enzymatic activity compared to other immobilization methods. In addition, this derivative provided activity closer to the soluble enzyme activity (3.30 U) and better storage stability, and allows reuse for more than 8 cycles. In turn, the peptides from casein hydrolysis showed potential as antioxidant agents, with a DPPH radical scavenging activity higher than 70%, maximum protection against β-carotene oxidation close to 70%, and a maximum reducing power of Fe(III) into Fe(II) of 400 uM by the FRAP assay. The results showed that the new techniques for modification of activated carbon can be a promising approach for pepsin immobilization.

Jackfruit seeds have been explored as one interesting alternative starch source to be used in the production of sustainable bioplastics. In this context, this work aimed to investigate the effect of sorbitol concentration, one alternative plasticizer to glycerol, and the starch properties of the films. A complete factorial experimental study was done based on five different concentrations of starch (2, 3, 4, 5, and 6% w/w) and sorbitol (40, 50, 60, 70, 80 g per 100 g of starch). The films were produced by casting technique and were characterized about thickness, optical properties, moisture resistance, mechanical properties, and morphology. The optical properties revealed opaque films, with opacity values ranging from 16.04 to 21.26%. Regarding moisture resistance, the less hydrophilic films showed lower plasticizer content. The water solubility varied from 25.48 to 38.93%; the water vapor permeability ranged from 9.99 to 11.82 × 10 −9 (g/m s Pa) and the free energy of hydrophobic interactions varied from − 28.16 to 40.13 mJ m −1 . Concerning the mechanical properties, the tensile strength of the films ranged from 3.55 to 9.25 MPa, and increasing the sorbitol concentration decreased the tensile strength and increased the elongation at break. The morphology and structure analysis showed that starch granules were not fully gelatinized, with microbubbles and grooves in the film matrix. This study showed the great potential of jackfruit seed starch and sorbitol in the manufacture of biodegradable films as alternative sustainable packaging.

A reversed-field pinch is a toroidal device for magnetically confining plasmas, and a potential alternative to the tokamak for a future fusion reactor. Observations of the evolution of a reversed-field-pinch plasma towards a self-organized single-helicity state suggest that instability problems, which have previously hindered the development of these devices, could now be overcome. In the quest for new energy sources, the research on controlled thermonuclear fusion 1 has been boosted by the start of the construction phase of the International Thermonuclear Experimental Reactor 2 (ITER). ITER is based on the tokamak magnetic configuration 3 , which is the best performing one in terms of energy confinement. Alternative concepts are however actively researched, which in the long term could be considered for a second generation of reactors. Here, we show results concerning one of these configurations, the reversed-field pinch 4 , 5 (RFP). By increasing the plasma current, a spontaneous transition to a helical equilibrium occurs, with a change of magnetic topology. Partially conserved magnetic flux surfaces emerge within residual magnetic chaos, resulting in the onset of a transport barrier. This is a structural change and sheds new light on the potential of the RFP as the basis for a low-magnetic-field ohmic fusion reactor.

Drying is a unit operation widely used in food preservation. It is important to know how this process takes place and the effects of variables such as temperature, relative humidity and air velocity. It is also essential to know the equilibrium moisture content of the product at the temperature under study. Thus, the objective of this study was to determine the sorption isotherms and evaluate the effects of temperature (60°C and 75°C) and air velocity (1.5 m s-1 and 3.0 m s-1) on the thin-layer drying curves of green bell peppers. The experimental sorption data were adjusted to the BET and GAB models, where the latter best described the sorption behavior of the pepper. It was also verified that with the elevation in temperature lower values for the equilibrium moisture content were obtained. The drying data were adjusted to the Page model, Henderson and Pabis model, Newton model and Fick model. From the latter model the effective diffusion coefficient of water in the project was determined, confirming that the increase in temperature did not increase with greater air velocity. The Page model was that which best fit to all drying conditions. The variation in drying air velocity little affected the kinetics of the process, observing only a small reduction in drying time with increased air velocity (approximately 2.4%), while temperature showed the greatest influence, with a large reduction in drying time with increase in this variable (around 41.4%).

Northern China has been identified as an independent centre of domestication for various types of millet and other plant species, but tracing the earliest evidence for the exploitation of wild cereals and thus the actual domestication process has proven challenging. Evidence from microscopic analyses of stone tools, including use-wear, starch and phytolith analyses, however, show that in the Shizitan region of north China, various plants have been exploited as far back as 28 000years ago, and wild millets have been harvested and processed by the time of the Last Glacial Maximum, 24 000 years ago. This is some 18 000-14 000 years before the earliest evidence for domesticated millet in this region.