7,358 research outputs found
An investigation of using pyrolysis bio-oil as part of the binder system for wood-based composites
he objective of this research was to investigate the feasibility of using the pyrolysis bio-oil as part of a binder system for wood-based composites. Liquid products obtained from pyrolysis process of pine wood were mixed with reactants, such as isocyanate. The adhesive binder system was blended with flakes to fabricate flakeboard. The effect of the resin content and the mix ratio of the adhesive on the physical and mechanical properties of the flakeboard were examined. Dynamic mechanical analysis (DMA) was also employed to investigate the thermal properties of the adhesives. The results indicated that a bio-oil content of 25% showed comparable properties to those produced by pure pMDI adhesive. A good correlation between the DMA results and the mechanical properties of the flakeboard was also obtained. The increase of bio-oil content in the adhesive system improved the curing speed but reduced the adhesive stiffness
An investigation of using pyrolysis bio-oil as part of the binder system for wood-based composites
he objective of this research was to investigate the feasibility of using the pyrolysis bio-oil as part of a binder system for wood-based composites. Liquid products obtained from pyrolysis process of pine wood were mixed with reactants, such as isocyanate. The adhesive binder system was blended with flakes to fabricate flakeboard. The effect of the resin content and the mix ratio of the adhesive on the physical and mechanical properties of the flakeboard were examined. Dynamic mechanical analysis (DMA) was also employed to investigate the thermal properties of the adhesives. The results indicated that a bio-oil content of 25% showed comparable properties to those produced by pure pMDI adhesive. A good correlation between the DMA results and the mechanical properties of the flakeboard was also obtained. The increase of bio-oil content in the adhesive system improved the curing speed but reduced the adhesive stiffness
Electronic structure and Magnetism in BaMnAs and BaMnSb
We study the properties of ThCrSi structure BaMnAs and
BaMnSb using density functional calculations of the electronic and
magnetic as well experimental measurements on single crystal samples of
BaMnAs. These materials are local moment magnets with moderate band gap
antiferromagnetic semiconducting ground states. The electronic structures show
substantial Mn - pnictogen hybridization, which stabilizes an intermediate spin
configuration for the nominally Mn. The results are discussed in the
context of possible thermoelectric applications and the relationship with the
corresponding iron / cobalt / nickel compounds Ba(Fe,Co,Ni)As
Optical Gravitational Lensing Experiment. OGLE-1999-BUL-19: The First Multi-Peak Parallax Event
We describe a highly unusual microlensing event, OGLE-1999-BUL-19, which
exhibits multiple peaks in its light curve. The Einstein radius crossing time
for this event is approximately one year, which is unusually long. We show that
the motion of the Earth induces these multiple peaks in the light curve, since
the relative transverse velocity of the lens projected into the observer plane
is very small (v = 12.5 km/s). This is the lowest velocity so far published and
we believe that this is the first multiple-peak parallax event ever observed.
We also believe that this event may be exhibiting slight binary-source
signatures in addition to these parallax-induced multiple peaks. With
spectroscopic observations it is possible to test this `parallax plus
binary-source' hypothesis and (if this hypothesis turns out to be correct) to
simultaneously fit both models and obtain a measurement of the lens mass.
Furthermore, spectroscopic observations could also supply information regarding
the lens properties, possibly providing another avenue for determining the lens
mass. We found that most of the I-band blending is probably caused by light
from the lens or a binary companion to the source. However, in the V-band,
there appears to be a second blended source 0.35" away from the lensed source.
HST observations will be very useful for understanding the nature of the
blends. We also suggest that a radial velocity survey of all parallax events
will be very useful for further constraining the lensing kinematics and
understanding the origins of these events and the excess of long events toward
the bulge.Comment: 36 pages, 7 figures. Accepted for publication in MNRA
Recommended from our members
Single-Cell RNA Sequencing of hESC-Derived 3D Retinal Organoids Reveals Novel Genes Regulating RPC Commitment in Early Human Retinogenesis.
The development of the mammalian retina is a complicated process involving the generation of distinct types of neurons from retinal progenitor cells (RPCs) in a spatiotemporal-specific manner. The progression of RPCs during retinogenesis includes RPC proliferation, cell-fate commitment, and specific neuronal differentiation. In this study, by performing single-cell RNA sequencing of cells isolated from human embryonic stem cell (hESC)-derived 3D retinal organoids, we successfully deconstructed the temporal progression of RPCs during early human retinogenesis. We identified two distinctive subtypes of RPCs with unique molecular profiles, namely multipotent RPCs and neurogenic RPCs. We found that genes related to the Notch and Wnt signaling pathways, as well as chromatin remodeling, were dynamically regulated during RPC commitment. Interestingly, our analysis identified that CCND1, a G1-phase cell-cycle regulator, was coexpressed with ASCL1 in a cell-cycle-independent manner. Temporally controlled overexpression of CCND1 in retinal organoids demonstrated a role for CCND1 in promoting early retinal neurogenesis. Together, our results revealed critical pathways and novel genes in early retinogenesis of humans
Finite element analysis of interaction of laser beam with material in laser metal powder bed fusion process
This is the final version of the article. Available from MDPI via the DOI in this record.A deep understanding of the laser-material interaction mechanism, characterized by laser absorption, is very important in simulating the laser metal powder bed fusion (PBF) process. This is because the laser absorption of material affects the temperature distribution, which influences the thermal stress development and the final quality of parts. In this paper, a three-dimensional finite element analysis model of heat transfer taking into account the effect of material state and phase changes on laser absorption is presented to gain insight into the absorption mechanism, and the evolution of instantaneous absorptance in the laser metal PBF process. The results showed that the instantaneous absorptance was significantly affected by the time of laser radiation, as well as process parameters, such as hatch space, scanning velocity, and laser power, which were consistent with the experiment-based findings. The applicability of this model to temperature simulation was demonstrated by a comparative study, wherein the peak temperature in fusion process was simulated in two scenarios, with and without considering the effect of material state and phase changes on laser absorption, and the simulated results in the two scenarios were then compared with experimental data respectively.This research was funded by the National High Technology Research and Development Program of
China [863 Program: 2015AA042501]
- …