226 research outputs found
Analysis of the economic impact of large-scale deployment of biomass resources for energy and materials in the Netherlands : macro-economics biobased synthesis report
The Bio-based Raw Materials Platform (PGG), part of the Energy Transition in The Netherlands, commissioned the Agricultural Economics Research Institute (LEI) and the Copernicus Institute of Utrecht University to conduct research on the macro-economic impact of large scale deployment of biomass for energy and materials in the Netherlands. Two model approaches were applied based on a consistent set of scenario assumptions: a bottom-up study including technoeconomic projections of fossil and bio-based conversion technologies and a topdown study including macro-economic modelling of (global) trade of biomass and fossil resources. The results of the top-down and bottom-up modelling work are reported separately. The results of the synthesis of the modelling work are presented in this report
On Micromechanical Parameter Identification With Integrated DIC and the Role of Accuracy in Kinematic Boundary Conditions
Integrated Digital Image Correlation (IDIC) is nowadays a well established
full-field experimental procedure for reliable and accurate identification of
material parameters. It is based on the correlation of a series of images
captured during a mechanical experiment, that are matched by displacement
fields derived from an underlying mechanical model. In recent studies, it has
been shown that when the applied boundary conditions lie outside the employed
field of view, IDIC suffers from inaccuracies. A typical example is a
micromechanical parameter identification inside a Microstructural Volume
Element (MVE), whereby images are usually obtained by electron microscopy or
other microscopy techniques but the loads are applied at a much larger scale.
For any IDIC model, MVE boundary conditions still need to be specified, and any
deviation or fluctuation in these boundary conditions may significantly
influence the quality of identification. Prescribing proper boundary conditions
is generally a challenging task, because the MVE has no free boundary, and the
boundary displacements are typically highly heterogeneous due to the underlying
microstructure. The aim of this paper is therefore first to quantify the
effects of errors in the prescribed boundary conditions on the accuracy of the
identification in a systematic way. To this end, three kinds of mechanical
tests, each for various levels of material contrast ratios and levels of image
noise, are carried out by means of virtual experiments. For simplicity, an
elastic compressible Neo-Hookean constitutive model under plane strain
assumption is adopted. It is shown that a high level of detail is required in
the applied boundary conditions. This motivates an improved boundary condition
application approach, which considers constitutive material parameters as well
as kinematic variables at the boundary of the entire MVE as degrees of freedom
in...Comment: 37 pages, 25 figures, 2 tables, 2 algorithm
Cost optimization of biofuel production – The impact of scale, integration, transport and supply chain configurations
This study uses a geographically-explicit cost optimization model to analyze the impact of and interrelation between four cost reduction strategies for biofuel production: economies of scale, intermodal transport, integration with existing industries, and distributed supply chain configurations (i.e. supply chains with an intermediate pre-treatment step to reduce biomass transport cost). The model assessed biofuel production levels ranging from 1 to 150 PJ a−1 in the context of the existing Swedish forest industry. Biofuel was produced from forestry biomass using hydrothermal liquefaction and hydroprocessing. Simultaneous implementation of all cost reduction strategies yielded minimum biofuel production costs of 18.1–18.2 € GJ−1 at biofuel production levels between 10 and 75 PJ a−1. Limiting the economies of scale was shown to cause the largest cost increase (+0–12%, increasing with biofuel production level), followed by disabling integration benefits (+1–10%, decreasing with biofuel production level) and allowing unimodal truck transport only (+0–6%, increasing with biofuel production level). Distributed supply chain configurations were introduced once biomass supply became increasingly dispersed, but did not provide a significant cost benefit (<1%). Disabling the benefits of integration favors large-scale centralized production, while intermodal transport networks positively affect the benefits of economies of scale. As biofuel production costs still exceeds the price of fossil transport fuels in Sweden after implementation of all cost reduction strategies, policy support and stimulation of further technological learning remains essential to achieve cost parity with fossil fuels for this feedstock/technology combination in this spatiotemporal context
Ultra-stretchable Interconnects for high-density stretchable electronics
The exciting field of stretchable electronics (SE) promises numerous novel applications, particularly in-body and medical diagnostics devices. However, future advanced SE miniature devices will require high-density, extremely stretchable interconnects with micron-scale footprints, which calls for proven standardized (complementary metal-oxide semiconductor (CMOS)-type) process recipes using bulk integrated circuit (IC) microfabrication tools and fine-pitch photolithography patterning. Here, we address this combined challenge of microfabrication with extreme stretchability for high-density SE devices by introducing CMOS-enabled, free-standing, miniaturized interconnect structures that fully exploit their 3D kinematic freedom through an interplay of buckling, torsion, and bending to maximize stretchability. Integration with standard CMOS-type batch processing is assured by utilizing the Flex-to-Rigid (F2R) post-processing technology to make the back-end-of-line interconnect structures free-standing, thus enabling the routine microfabrication of highly-stretchable interconnects. The performance and reproducibility of these free-standing structures is promising: an elastic stretch beyond 2000% and ultimate (plastic) stretch beyond 3000%, with <0.3% resistance change, and >10 million cycles at 1000% stretch with <1% resistance change. This generic technology provides a new route to exciting highly-stretchable miniature devices.</p
Effect of restrained versus free drying on hygro-expansion of hardwood and softwood fibers and paper handsheet
Earlier works in literature on the hygro-expansion of paper state that the
larger hygro-expansivity of freely compared to restrained dried handsheets is
due to structural differences between the fibers inside the handsheet. To
unravel this hypothesis, first, the hygro-expansion of freely and restrained
dried, hardwood and softwood handsheets has been characterized. Subsequently,
the transient full-field hygro-expansion (longitudinal, transverse, and shear
strain) of fibers extracted from these handsheets was measured using global
digital height correlation, from which the micro-fibril angle was deduced. The
hygro-expansivity of each individual fiber was tested before and after a
wetting period, during which the fiber's moisture content is maximized, to
analyze if a restrained dried fiber can "transform" into a freely dried fiber.
It was found that the longitudinal hygro-expansion of the freely dried fibers
is significantly larger than the restrained dried fibers, consistent with the
sheet-scale differences. The difference in micro-fibril angle between the
freely and restrained dried fibers is a possible explanation for this
difference, but merely for the hardwood fibers, which are able to "transform"
to freely dried fibers after being soaked in water. In contrast, this
"transformation" does not happen in softwood fibers, even after full immersion
in water for a day. Various mechanisms have been studied to explain the
observations on freely and restrained dried hardwood and softwood, fiber and
handsheets including analysis of the fibers' lumen and cross-sectional shape.
The presented results and discussion deepens the understanding of the
differences between freely and restrained dried handsheets.Comment: 43 pages, 15 figures, 2 table
Experimental Full-field Analysis of Size Effects in Miniaturized Cellular Elastomeric Metamaterials
Cellular elastomeric metamaterials are interesting for various applications,
e.g. soft robotics, as they may exhibit multiple microstructural pattern
transformations, each with its characteristic mechanical behavior. Numerical
literature studies revealed that pattern formation is restricted in (thick)
boundary layers causing significant mechanical size effects. This paper aims to
experimentally validate these findings on miniaturized specimens, relevant for
real applications, and to investigate the effect of increased geometrical and
material imperfections resulting from specimen miniaturization. To this end,
miniaturized cellular metamaterial specimens are manufactured with different
scale ratios, subjected to in-situ micro-compression tests combined with
digital image correlation yielding full-field kinematics, and compared to
complementary numerical simulations. The specimens' global behavior agrees well
with the numerical predictions, in terms of pre-buckling stiffness, buckling
strain and post-buckling stress. Their local behavior, i.e. pattern
transformation and boundary layer formation, is also consistent between
experiments and simulations. Comparison of these results with idealized
numerical studies from literature reveals the influence of the boundary
conditions in real cellular metamaterial applications, e.g. lateral
confinement, on the mechanical response in terms of size effects and boundary
layer formation.Comment: 20 pages, 6 figures, Materials & Design, 11 May 202
Transient hygro- and hydro-expansion of freely and restrained dried paper: the fiber-network coupling
The transient dimensional changes during \textit{hygro}-expansion and
\textit{hydro}-expansion of freely and restrained dried, softwood and hardwood
sheets and fibers is monitored, to unravel the governing micro-mechanisms
occurring during gradual water saturation. The response of individual fibers is
measured using a full-field global digital height correlation method, which has
been extended to monitor the transient \textit{hydro}-expansion of fibers from
dry to fully saturated. The \textit{hygro}- and \textit{hydro}-expansion is
larger for freely versus restrained dried and softwood versus hardwood
handsheets. The transient sheet-scale \textit{hydro}-expansion reveals a sudden
strain and moisture content step. It is postulated that the driving mechanism
is the moisture-induced softening of the so-called "dislocated regions" in the
fiber's cellulose micro-fibrils, unlocking further fiber swelling. The strain
step is negligible for restrained dried handsheets, which is attributed to the
"dislocated cellulose regions" being locked in their stretched configuration
during restrained drying, which is supported by the single fiber
\textit{hydro}-expansion measurements. Finally, an inter-fiber bond model is
exploited and adapted to predict the sheet-scale \textit{hygro}-expansion from
the fiber level characteristics. The model correctly predicts the qualitative
differences between freely versus restrained dried and softwood versus hardwood
handsheets, yet, its simplified geometry does not allow for more quantitative
predictions of the sheet-scale \textit{hydro}-expansion.Comment: 37 pages; 12 figures; 5 table
Metrics for minimising environmental impacts while maximising circularity in biobased products: The case of lignin-based asphalt
Achieving a circular economy (CE) is seen by society and policymakers as crucial to achieving a sustainable, resource-efficient, renewable and competitive economy. Given the current threat of climate change, we must develop new products that not only maximise the circularity of resources but also minimise climate change impacts. While these two goals are usually aligned, trade-offs exist. For instance, recycling biobased asphalt is a better end-of-life option than landfilling from a resource efficiency perspective. However, landfilling of biogenic non-biodegradable material leads to permanent carbon storage and, therefore, climate benefits. To fully understand the potential benefits and impacts of biobased circular innovations, we need metrics to capture their complexity from both a circular and climate point of view. This study explores the use of different circularity and sustainability metrics to understand the impacts and trade-offs of lignin-based versus bitumen-based asphalts. The analysis is done by calculating the Material Circularity Index (MCI) and two newly developed indicators quantifying the biogenic carbon storage (BCS) of products (BCS100 and c-BCS) while following the CE principles. In addition, the impacts regarding climate change, life cycle costs and ECI (environmental costs indicator) are also provided. Based on the MCI, it can be concluded that lignin-based asphalt roads have slightly higher material circularity than their bitumen-based counterparts. The BCS analysis indicated that the least circular lignin-based alternative sequesters the highest amount of carbon in the long term due to permanent storage in foundations. Despite these trade-offs, the results from the newly developed BCS indicators allowed to align both climate and circularity goals, guiding policymakers and industry actors to implement circular biobased strategies where the value of biobased materials is optimised. Finally, this article discusses the use of different circularity and environmental metrics for decision making in the context of a circular biobased economy
Clinical profiles of patients colonized or infected with extended-spectrum beta-lactamase producing Enterobacteriaceae isolates: a 20 month retrospective study at a Belgian University Hospital
<p>Abstract</p> <p>Background</p> <p>Description of the clinical pictures of patients colonized or infected by ESBL-producing <it>Enterobacteriaceae </it>isolates and admitted to hospital are rather scarce in Europe. However, a better delineation of the clinical patterns associated with the carriage of ESBL-producing isolates may allow healthcare providers to identify more rapidly at risk patients. This matter is of particular concern because of the growing proportion of ESBL-producing <it>Enterobacteriaceae </it>species isolates worldwide.</p> <p>Methods</p> <p>We undertook a descriptive analysis of 114 consecutive patients in whom ESBL-producing <it>Enterobacteriaceae </it>isolates were collected from clinical specimens over a 20-month period. Clinical data were obtained through retrospective analysis of medical record charts. Microbiological cultures were carried out by standard laboratory methods.</p> <p>Results</p> <p>The proportion of ESBL-producing <it>Enterobacteriaceae </it>strains after exclusion of duplicate isolates was 4.5% and the incidence rate was 4.3 cases/1000 patients admitted. Healthcare-associated acquisition was important (n = 104) while community-acquisition was less frequently found (n = 10). Among the former group, two-thirds of the patients were aged over 65 years and 24% of these were living in nursing homes. Sixty-eight (65%) of the patients with healthcare-associated ESBL, were considered clinically infected. In this group, the number and severity of co-morbidities was high, particularly including diabetes mellitus and chronic renal insufficiency. Other known risk factors for ESBL colonization or infection such as prior antibiotic exposure, urinary catheter or previous hospitalisation were also often found. The four main diagnostic categories were: urinary tract infections, lower respiratory tract infections, septicaemia and intra-abdominal infections. For hospitalized patients, the median hospital length of stay was 23 days and the average mortality rate during hospitalization was 13% (Confidence Interval 95%: 7-19). <it>Escherichia coli</it>, by far, accounted as the most common ESBL-producing <it>Enterobacteriaceae </it>species (77/114; [68%]) while CTX-M-1 group was by far the most prevalent ESBL enzyme (n = 56).</p> <p>Conclusion</p> <p>In this retrospective study, the clinical profiles of patients carrying healthcare-associated ESBL-producing <it>Enterobacteriacae </it>is characterized by a high prevalence rate of several major co-morbidities and potential known risk factors. Both, the length of hospital stay and overall hospital mortality rates were particularly high. A prospective case-control matched study should be designed and performed in order to control for possible inclusion bias.</p
Attenuated total reflection infrared spectroscopy for studying adsorbates on planar model catalysts : CO adsorption on silica supported Rh nanoparticles
A sensitive method is presented for studying adsorption of gaseous species on metal surfaces in vacuum by attenuated total internal reflection Fourier transform IR spectroscopy (ATR). The method is illustrated by CO adsorption expts. on silica supported Rh nanoparticles. An exptl. setup and a procedure are described in detail to obtain a sensitivity of reflectance change of .apprx.5 * 10-5 absorbance units. Here, a silicon ATR crystal with a 50 nm layer of hydroxylated silica acts as the support for the Rh nanoparticles. These particles are easily prepd. by spincoat impregnation from a RhCl3 soln. followed by H2 redn. XPS before and after redn. shows that rhodium is reduced to Rh0 and that all chlorine is removed. At. force microscope images the distribution of the particles, which are 3-4 nm in height. When the crystal is exposed to pressures up to 1 mbar of CO, a gas which is inert to the silica support, the stretch vibration of linearly adsorbed CO on the Rh nanoparticles is detected at 2023 cm-1, while no bridged CO or geminal dicarbonyl species can be distinguished. The min. detectable coverage is estd. .apprx.0.005 CO per nm2 substrate area or .apprx.5 * 10-4 ML. [on SciFinder (R)
- …