Sweet Clovers, a Source of Fibers Adapted for Growth on Wet and Saline Soils

Sweet clovers are legumes able to grow on most soils, and two sweet clover species, Melilotus albus and Melilotus officinalis have been introduced and are now cultivated on estuary land. We characterized the composition and morphology of sweet clover stems collected after the seeds had reached maturity. We also carried out histochemical analyses on transverse sections. The two species had similar morphological structures, which two fiber fractions: flexible long fibers and stiff, dense shives, accounting for about 12% and 88% of stem dry matter, respectively. Histological analysis revealed the presence of bundles of highly cellulosic bast fibers (lignocellulosic material: 71–78% of dry matter). The shives are a natural mesoporous material composed of 85–90% lignocellulosic fibers. Both fiber fractions displayed good thermal resistance to temperatures up to 225°C and a moderate affinity for water. These two types of fibers are similar to those of flax and hemp, suggesting their possible use for the same types of applications. Sweet clovers therefore constitute a new source of fibers that can be cultivated on wet and saline soils not otherwise suitable for agriculture

Grand Dyck paths with air pockets

Grand Dyck paths with air pockets (GDAP) are a generalization of Dyck paths with air pockets by allowing them to go below the $x$-axis. We present enumerative results on GDAP (or their prefixes) subject to various restrictions such as maximal/minimal height, ordinate of the last point and particular first return decomposition. In some special cases we give bijections with other known combinatorial classes.Comment: 20 pages, 4 figure

Biomass pretreatment with reactive extrusion using enzymes: A review

Introducing enzymes during the extrusion process has been mainly used as new pretreatment techniques in the starch degradation process and, more recently, in the second generation bioethanol production. The technique, called the bioextrusion, is a special case of reactive extrusion. Starch and lignocellulose bioextrusion examples underline the good mixing capacities as a way to initiate the enzymatic reaction in high solid content conditions. Starch bioextrusion results show a low dextrinization yield but a real effect on the polymer size decrease which allows higher and faster subsequent saccharification. It also considerably reduced the recrystallization phenomenon that limits the saccharification efficiency. Bioextrusion of lignocellulose resulted in a better sugar production. Very short residence times limit the use of bioextrusion to a pretreatment technique. However, unique flexibility of the extrusion technique allows to subsequently pretreat, in the same extruder, with physical and/or chemical constraining conditions, followed by a milder bioextrusion

Feasibility study of a CO2-based system in NEST

The NEST building laboratory of Empa and Eawag is a modular research and innovation demonstrator where new technologies, materials and systems are tested, researched, honed and validated in realistic conditions. In the NEST concept, only the supporting structure is permanent and all the habitable units are interchangeable. Moreover, the site is hosting an energy research and technology transfer platform (ehub) aiming at optimizing energy management at district level and a demonstrator for future mobility working without fossil energy (move). Therefore, the NEST research platform seems to be an appropriate place for the implementation of a demonstrator of advanced 4th Generation District Heating and Cooling systems (4G-DHC). This study demonstrates the feasibility of a CO2-based district energy network in NEST. The report includes a concise project plan and budget positions for the concept, planning, installation and operation phase

Manufacturing of renewable and biodegradable fiberboards from cake generated during biorefinery of sunflower whole plant in twin-screw extruder: Influence of thermo-pressing conditions

The starting material used in this study was a cake generated during thermo-mechanical fractionation of sunflower (Helianthus annuus L.) whole plant in a twin-screw extruder. It was slightly deoiled (16.7% of oil in dry matter). Composed mainly of fibers and proteins, it could be considered as a natural composite and was processed successfully into fiberboards by thermo-pressing. This study aimed to evaluate the influence of thermo-pressing conditions on mechanical and heat insulation properties of fiberboards manufactured from this cake. All fiberboards were cohesive, proteins and fibers acting respectively as binder and reinforcing fillers. Highest cake quantity (1000 mg/cm²) led to the highest breaking load (60.7 N) with a flexural strength at break quite low (2.9 MPa), lowest elastic modulus (216.6 MPa), and highest Charpy impact strength (6.5 kJ/m² for resilience). The increase of pressure applied during molding (from 320 to 360 kgf/cm²) led to an important increase of elastic modulus (from 352.6 to 728.6 MPa). Besides, fiberboard molded at 360 kgf/cm² was the most rigid of this study, and logically revealed the most important Shore D surface hardness (52.6°). Moreover, lowest molding time (60 s) led to the highest flexural strength at break (3.9 MPa). The low density of the fiberboards (less than 0.97) involved promising heat insulation properties. Indeed, thermal conductivity of fiberboards at 25 °C was low (from 103.5 to 135.7 mW/m K), and decreased with the increase of thickness. According to their mechanical and heat insulation properties, fiberboards would be potentially usable as inter-layer sheets for pallets, for the manufacture of biodegradable containers (composters, crates for vegetable gardening) by assembly of fiberboards, or for their heat insulation properties in building industry. Moreover, thermo-pressing was not only a molding operation. It also improved the oil extraction efficiency as a part of residual oil was expressed from cake during molding, and total oil yield reached 79.3% with a pressure applied of 360 kgf/cm²

BIGRE: a low cross-talk integral field unit tailored for extrasolar planets imaging spectroscopy

Integral field spectroscopy (IFS) represents a powerful technique for the detection and characterization of extrasolar planets through high contrast imaging, since it allows to obtain simultaneously a large number of monochromatic images. These can be used to calibrate and then to reduce the impact of speckles, once their chromatic dependence is taken into account. The main concern in designing integral field spectrographs for high contrast imaging is the impact of the diffraction effects and the non-common path aberrations together with an efficient use of the detector pixels. We focus our attention on integral field spectrographs based on lenslet-arrays, discussing the main features of these designs: the conditions of appropriate spatial and spectral sampling of the resulting spectrograph's slit functions and their related cross-talk terms when the system works at the diffraction limit. We present a new scheme for the integral field unit (IFU) based on a dual-lenslet device (BIGRE), that solves some of the problems related to the classical TIGER design when used for such applications. We show that BIGRE provides much lower cross-talk signals than TIGER, allowing a more efficient use of the detector pixels and a considerable saving of the overall cost of a lenslet-based integral field spectrograph.Comment: 17 pages, 18 figures, accepted for publication in Ap

Influence of temperature and soda concentration in a thermo-mechano-chemical pretreatment for bioethanol production from sweet corn co-products

A continuous process combining an alkaline pretreatment, neutralization and injection of enzymes within a twin screw extruder was previously implemented and demonstrate industrial potential. The present work focuses on the investigation of the effects of alkali and temperature during the alkaline pretreatment of sweet corn co-products (SCC) for the production of fermentable sugars with a lower chemical input. Study of NaOH/SCC and internal temperature was performed in ranges of 4–8% (w/w) and 50–170 °C in a laboratory scale twin screw extruder. Analysis of carbohydrates and lignin of the pretreated biomass was performed and the filtration efficiency was also monitored through extrudate dry matter and filtrate mineral matter. The carbohydrate accessibility and process performances were studied by the enzymatic hydrolysis of the extrudate. Increasing temperature reinforces the effects of soda on solubilization of hemicelluloses, thus a hemicelluloses removal reach more than 50%. At optimal conditions, the cellulose-rich substrate after enzymatic hydrolysis achieve a glucose released of 70%, with glucose and xylose yields of 250 g per 1Kg of dry SCC