Preparation and properties of polypropylene composites reinforced with wheat and flax straw fibres - Part 1: Fibre characterization

Copyright @ 1997 Chapman and Hall. This article is the author version of the published article which can be accessed at the link below.The microstructure, thermal and mechanical properties of flax and wheat straw fibres have been examined with a view to using these natural fibres as reinforcing additives for thermoplastics. In this regard, the fibres were characterized prior to incorporation into the polymer, using a range of techniques, including SEM, image analysis, thermogravimetric analysis and micro-mechanical tensile testing, at room and elevated temperatures. The thermal and mechanical properties obtained have been discussed in relation to the measured composition and structural form of the fibres.This work was supported by the EPSRC, DTI and Cookson Plantpak Ltd through the LINK Crops for Industrial Use programme

Preparation and properties of polypropylene composites reinforced with wheat and flax straw fibres - Part 2: Analysis of composite microstructure and mechanical properties

Copyright @ 1997 Chapman and Hall. This article is the author version of the published article which can be accessed at the link below.The microstructure and mechanical properties of polypropylene composites containing flax and wheat straw fibres are discussed. Particular emphasis has been given to determining the nature and consequences of fibre damage induced during melt-processing operations, fibre orientation occurring in mouldings, and possible interfacial adhesion between the matrix and fibres. Compared to unfilled polypropylene, addition of flax and wheat straw caused a significant increase in tensile modulus, particularly, in the case of flax fibres, which also gave higher tensile yield strength and Charpy toughness, despite a lack of interfacial bonding. Tensile strength was increased further through inclusion of 5% by weight of maleic anhydride-modified polypropylene, which was shown to promote adhesion between fibres and matrix.This work was supported by the EPSRC, DTI and Cookson Plantpak Ltd through the LINK Crops for Industrial Use programme

Effects of grain by-products as supplements for stocker cattle grazing bermudagrass

Two experiments were conducted to compare corn, dried distillers’ grains (DDG), and pelleted soybean hulls (SH) as supplements for cattle grazing bermudagrass. In Exp. 1, 66 crossbred steers (306 ± 3.2 kg) were stratified by weight and allotted randomly to six 2.4-ha bermudagrass pastures for a 107-d study. One of three supplement treatments (corn, DDG, or SH) was assigned randomly to each pasture group and was offered at 0.5% (as fed) of body weight. Calves were weighed at 28-d intervals and supplement was adjusted after each weigh period. In Exp. 2, five ruminally cannulated steers grazed bermudagrass pasture and were individually fed supplements (corn, DDG, or SH) at 0.5% of body weight in a 3 x 3 replicated, incomplete Latin-square design with a 14-d adaptation and a 5-d sampling period. In Exp. 1, supplementation with DDG and corn increased (P \u3c 0.04) the average daily gain compared to supplementation with SH (0.89, 0.87, and 0.74 kg for DDG, corn, and SH, respectively). In Exp. 2, in situ dry-matter-disappearance kinetic measures of bermudagrass were not affected by type of supplementation. The potential extent of digestion for DDG (93%) was lower than for corn (97%, P = 0.01) and SH (96%, P = 0.06). Supplementation with corn or DDG at 0.5% of body weight improved the gain of stocker cattle grazing bermudagrass compared to supplementation with SH, but these differences were not explained by differences in bermudagrass degradation kinetic

Fiber association and network formation in PLA/lignocellulosic fiber composites.

PLA composites were prepared in an internal mixer with a lignocellulosic fiber having relatively large aspect ratio. Fiber content changed between 0 and 60 vol% and the homogenized material was compression molded to 1 mm thick plates. The composites showed anomalous behavior above certain fiber content. Their modulus and especially their strength decreased drastically and modeling also proved the loss of reinforcement at large fiber contents. Micromechanical testing showed that the mechanism of deformation and failure changes at a critical fiber content. Microscopic analysis indi-cated the formation of a network purely from geometrical reasons. The inherent strength of the network is very small because of the weak forces acting among the fibers. This weak inherent strength makes the structure of the composites very sensitive to pro-cessing conditions, and decreases strength, reproducibility as well as reliability

Wide Field X-Ray Telescope Mission Concept Study Results

The Wide Field X-Ray Telescope (WFXT) is an astrophysics mission concept for detecting and studying extra-galactic x-ray sources, including active galactic nuclei and clusters of galaxies, in an effort to further understand cosmic evolution and structure. This Technical Memorandum details the results of a mission concept study completed by the Advanced Concepts Office at NASA Marshall Space Flight Center in 2012. The design team analyzed the mission and instrument requirements, and designed a spacecraft that enables the WFXT mission while using high heritage components. Design work included selecting components and sizing subsystems for power, avionics, guidance, navigation and control, propulsion, structures, command and data handling, communications, and thermal control

Advanced X-Ray Timing Array Mission: Conceptual Spacecraft Design Study

The Advanced X-Ray Timing Array (AXTAR) is a mission concept for submillisecond timing of bright galactic x-ray sources. The two science instruments are the Large Area Timing Array (LATA) (a collimated instrument with 2-50-keV coverage and over 3 square meters of effective area) and a Sky Monitor (SM), which acts as a trigger for pointed observations of x-ray transients. The spacecraft conceptual design team developed two spacecraft concepts that will enable the AXTAR mission: A minimal configuration to be launched on a Taurus II and a larger configuration to be launched on a Falcon 9 or similar vehicle

A Fuzzy Spatio-Temporal-based Approach for Activity Recognition

International audienceOver the last decade, there has been a significant deployment of systems dedicated to surveillance. These systems make use of real-time sensors that generate continuous streams of data. Despite their success in many cases, the increased number of sensors leads to a cognitive overload for the operator in charge of their analysis. However, the context and the application requires an ability to react in real-time. The research presented in this paper introduces a spatio-temporal-based approach the objective of which is to provide a qualitative interpretation of the behavior of an entity (e.g., a human or vehicle). The process is formally supported by a fuzzy logic-based approach, and designed in order to be as generic as possible

Calorie restriction activates new adult born olfactory‐bulb neurones in a ghrelin‐dependent manner but acyl‐ghrelin does not enhance subventricular zone neurogenesis

The ageing and degenerating brain show deficits in neural stem/progenitor cell (NSPC) plasticity that are accompanied by impairments in olfactory discrimination. Emerging evidence suggests that the gut hormone ghrelin plays an important role in protecting neurones, promoting synaptic plasticity and increasing hippocampal neurogenesis in the adult brain. In the present study, we investigated the role of ghrelin with respect to modulating adult subventricular zone (SVZ) NSPCs that give rise to new olfactory bulb (OB) neurones. We characterised the expression of the ghrelin receptor, growth hormone secretagogue receptor (GHSR), using an immunohistochemical approach in GHSR‐eGFP reporter mice to show that GHSR is expressed in several regions, including the OB but not in the SVZ of the lateral ventricle. These data suggest that acyl‐ghrelin does not mediate a direct effect on NSPC in the SVZ. Consistent with these findings, treatment with acyl‐ghrelin or genetic silencing of GHSR did not alter NSPC proliferation within the SVZ. Similarly, using a bromodeoxyuridine pulse‐chase approach, we show that peripheral treatment of adult rats with acyl‐ghrelin did not increase the number of new adult‐born neurones in the granule cell layer of the OB. These data demonstrate that acyl‐ghrelin does not increase adult OB neurogenesis. Finally, we investigated whether elevating ghrelin indirectly, via calorie restriction (CR), regulated the activity of new adult‐born cells in the OB. Overnight CR induced c‐Fos expression in new adult‐born OB cells but not in developmentally born cells, whereas neuronal activity was absent following re‐feeding. These effects were not present in ghrelin−/− mice, suggesting that adult‐born cells are uniquely sensitive to changes in ghrelin mediated by fasting and re‐feeding. In summary, ghrelin does not promote neurogenesis in the SVZ and OB; however, new adult‐born OB cells are activated by CR in a ghrelin‐dependent manner

Xenia Mission: Spacecraft Design Concept

The proposed Xenia mission will, for the first time, chart the chemical and dynamical state of the majority of baryonic matter in the universe. using high-resolution spectroscopy, Xenia will collect essential information from major traces of the formation and evolution of structures from the early universe to the present time. The mission is based on innovative instrumental and observational approaches: observing with fast reaction gamma-ray bursts (GRBs) with a high spectral resolution. This enables the study of their (star-forming) environment from the dark to the local universe and the use of GRBs as backlight of large-scale cosmological structures, observing and surveying extended sources with high sensitivity using two wide field-of-view x-ray telescopes - one with a high angular resolution and the other with a high spectral resolution

Cryogenic Propellant Storage and Transfer Technology Demonstration: Prephase A Government Point-of-Departure Concept Study

The primary purpose of this study was to define a point-of-departure prephase A mission concept for the cryogenic propellant storage and transfer technology demonstration mission to be conducted by the NASA Office of the Chief Technologist (OCT). The mission concept includes identification of the cryogenic propellant management technologies to be demonstrated, definition of a representative mission timeline, and definition of a viable flight system design concept. The resulting mission concept will serve as a point of departure for evaluating alternative mission concepts and synthesizing the results of industry- defined mission concepts developed under the OCT contracted studie