142 research outputs found
Hybrid modelling methodology for system design
In the face of rapid development in information technology coupled with a growing
dynamism in global markets, manufacturing systems have to be re-constructed for
short term or long term goal. Such innovations promise to lead to a new competitive
stage, which typically involve design of function, information and behaviour of
systems. In order to design the system, simulation has often been chosen. However,
simulation has proved limited and fails to aid design of such a complex systems
because of consuming much computing time and cost, especially when modelling
larger systems. Thus, there is a need to seek a new approach, in a way that results in
simulating such a large manufacturing system with less demand on computing time and
cost.
This study researches into a hybrid modelling approach to minimise these limitations. It
includes proposing a hybrid modelling methodology and developing a hybrid modelling
tool. The methodology integrates simulation and metamodelling techniques. The
metamodel employed in the study possesses, not only characteristics of conventional
metamodels in terms of representing relationships in quantity, but also in time lapse.
This is the originality of the study and the significant distinction between this research
and application of metamodelling in conventional ways. The hybrid modelling tool is
developed to support and demonstrate the identified hybrid methodology. LISP has
been used as the software language for the hybrid modelling tool. The result of this
work concludes that the hybrid modelling approach is capable of simulating a complex
manufacturing system with less demands on the computer.
The work reported in this thesis has been carried out in conjunction with the EPSRC
research project, Hierarchical Manufacturing System Modelling (HMSM)
(GR/F96549), to produce an Integrated Design and Modelling Methodology (IDEM).
The project was initially a collaborative research program including Loughborough
University of Technology (LUT), Morris Crane Ltd., of Loughborough and GEC
Large Machine, of Rugby. The experience of these collaborators has proved most
valuable in supporting the research, and have provided a cross section of views and
comments. The research reported in this thesis is set in the context of the HMSM
Research group at Loughborough
Multiresponsive Square Hybrid Nanosheets of POSS-Ended Hyperbranched Poly(ether amine) (hPEA)
We demonstrated a novel square hybrid nanosheet with
a ultrathin
thickness for the first time, which was fabricated by self-assembly
of hyperbranched poly(ether amine) (hPEA526) containing anthracene
(AN) moieties and heptaisobutyl polyhedral oligomeric silsesquioxane
(POSS). TEM and AFM images reveal that the average edge length and
thickness of the hybrid nanosheets formed by <b>HP1</b> is 1.2
± 0.2 μm and 4.5 ± 0.5 nm, respectively. POSS prefers
the ordered crystallized aggregation in the formation of the regular
square nanosheets, which is confirmed by WAXD and DSC studies. Moreover,
these nanosheets are cross-linked through dimerization of anthracene
moieties which makes the nanosheets more stable. The other functional
moieties such as naphthalene, pyrene, and dodecane can also be easily
introduced into the hybrid nanosheets through the same way. The obtained
hybrid nanosheets exhibit the multiresponses to temperature and pH,
and their dispersion in water can be controlled by temperature. The
fluorescence of the hybrid nanosheets decreases with the increasing
temperature and pH. The discovery of the hybrid nanosheets is believed
to provide a potential guiding significance on the preparation of
the functional nanosheets by self-assembly of polymers
Size-Tunable Nanosheets by the Crystallization-Driven 2D Self-Assembly of Hyperbranched Poly(ether amine) (hPEA)
We reported the preparation of uniform
square nanosheets with tunable size by the living crystallization-driven
2D self-assembly of hyperbranched poly(ether amine) capped with heptaisobutyl
polyhedral oligomeric silsesquioxane (POSS). The nanosheets of <b>HP1</b> containing both anthracene (AN) and POSS moieties in a
solution of 1,4-dioxane and water can be fragmented after the melting
of the POSS moieties upon heating and can be regenerated after the
recrystallization of POSS moieties, which was confirmed by microdifferential
scanning calorimetry (μDSC) and dynamic light scattering (DLS)
studies and transmission electron microscopy (TEM) images. The obtained
fragmented nanosheets (<b>HP1-NSs</b>) with a relatively small
size were used as seeds for the 2D epitaxial living growth of <b>HP1</b> unimers to fabricate uniform square nanosheets with tunable
edge lengths from ∼0.5 to ∼4.5 μm, which is dependent
on the unimer-to-seed ratio. Furthermore, dual-component nanosheets
can also be obtained by random cocrystallization of <b>HP1</b> with another type of hPEA capped with POSS and ferrocene (<b>HP2</b>). This crystallization-driven 2D self-assembly behavior
of POSS-capped hPEA might provide potential significance in the preparation
of functional nanosheets with different sizes and components, which
could be further used as templates for inorganic nanosheets and 2D-platforms
for metal nanoparticles
Hybrid Core–Shell Microspheres from Coassembly of Anthracene-Containing POSS (POSS-AN) and Anthracene-Ended Hyperbranched Poly(ether amine) (hPEA-AN) and Their Responsive Polymeric Hollow Microspheres
We
demonstrated a novel core–shell microsphere (CSM) fabricated
from coassembly of anthracene-ended hyperbranched poly(ether amine)
(hPEA-AN) and anthracene containing polyhedral oligomer silsesquioxane
(POSS-AN). The obtained CSMs are cross-linked through photodimerization
of anthracene and possess the well-defined core–shell structure
according to the images of SEM, TEM, and AFM. The shell of the obtained
CSM is comprised of hPEA-AN, while POSS-AN prefers the ordered crystallized
aggregation in the core. The size of the obtained CSMs is uniform
and tunable. With the increasing content of hPEA-AN in the coassembly,
the diameter of CSMs decreased from 930 to 616 nm, while the thickness
of shell increased from 95 to 170 nm. Moreover, polymeric hollow microsphere
(PHM) was prepared by removing the POSS-AN core of CSM in hydrofluoric
acid (HF). The obtained PHM is amphiphilic and fluorescent, and its
size is responsive to environmental stimulus such as temperature and
pH. PHM can be used in the encapsulation and controlled release of
guest molecules. Moreover, the controlled release of guest molecules
from PHM can be monitored by itself fluorescence change
Responsive Fluorescent Nanorods from Coassembly of Fullerene (C<sub>60</sub>) and Anthracene-Ended Hyperbranched Poly(ether amine) (AN-hPEA)
We
herein demonstrated a novel multiresponsive fluorescent nanorod based
on C<sub>60</sub>, which is fabricated through the versatile coassembly
of fullerene C<sub>60</sub> and anthracene-ended hyperbranched poly(ether
amine) (AN-hPEA). The supramolecular nanorods (C<sub>60</sub>@AN-hPEA)
can be further cross-linked through photodimerization of anthracene,
and the size of the obtained nanorods is 2–12 μm in length
and 50–90 nm in diameter. C<sub>60</sub>@AN-hPEA nanorods are
amphiphilic, responsive, and fluorescent. The fluorescence of C<sub>60</sub>@AN-hPEA nanorods in aqueous solution is responsive to temperature
and pH. The C<sub>60</sub>@AN-hPEA-1/4 nanorods exhibit the interesting
temperature-enhanced fluorescence, while the fluorescence intensity
of AN-hPEA without C<sub>60</sub> decreases with the increasing temperature.
Detailed fluorescence study revealed that the temperature-enhanced
fluorescence behavior of C<sub>60</sub>@AN-hPEA-1/4 nanorods might
be ascribed to the static quenching of the excited anthracene by C<sub>60</sub>
CO<sub>2</sub>‑Responsive Polymer Single-Chain Nanoparticles and Self-Assembly for Gas-Tunable Nanoreactors
CO<sub>2</sub>-responsive
polymer single-chain nanoparticles (SCNPs)
and self-assembled micellar aggregates are investigated as gas-controlled,
rate- and size-tunable nanoreactors of gold nanoparticles (AuNPs).
On one hand, SCNPs are prepared from a random copolymer of poly{(<i>N</i>,<i>N</i>-dimethylaminoethyl methacrylate)-<i>co</i>-4-methyl-[7-(methacryloyl)oxy-ethyl-oxy]coumarin} (P(DMAEMA-<i>co</i>-CMA)). When dispersed in aqueous solution, individual
nanoparticles can undergo reversible swelling/shrinking under alternating
CO<sub>2</sub>/N<sub>2</sub> stimulation as a result of the reversible
protonation/deprotonation of tertiary amine groups. On the other hand,
tadpole-like single-chain “Janus” nanoparticles (SCJNPs)
are prepared using an amphiphilic diblock copolymer of PS-<i>b</i>-P(DMAEMA-<i>co</i>-CMA) (PS is hydrophobic polystyrene).
This type of SCJNPs can self-assemble into core–shell micellar
aggregates in aqueous solution. Under CO<sub>2</sub>/N<sub>2</sub> stimulation, the collective swelling/shrinking of SCJNPs within
the micelle results in large, reversible volume change. Both P(DMAEMA-<i>co</i>-CMA) SCNPs and PS-<i>b</i>-P(DMAEMA-<i>co</i>-CMA) SCJNP micelles are explored as gas-tunable nanoreactors
for AuNPs. The rate of AuNP formation increases under CO<sub>2</sub> stimulation and decreases upon N<sub>2</sub> bubbling, which makes
it possible to tune the reaction rate up and down (on/off switching)
by using the two gases. Moreover, using the micelles of SCJNPs, whose
volume can be controlled over a wide range by adjusting the CO<sub>2</sub> stimulation strength, variable-size AuNPs and their aggregates
are obtained with continuous redshift of the surface plasmon resonance
(SPR) into the long-wavelength visible light region
Numbers of <i>C9orf72</i> repeats in white blood cell DNA of monozygous twins.
<p>T: twin pair, M: member,</p>¶<p>and §: CNS donors as well (see also <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0070007#pone-0070007-t001" target="_blank">Table 1</a>), NA: not applicable,</p>†<p>: cause and age of death,</p><p>♦: triplet, MZ: monozygous, DZ: dizygous, PMA: progressive muscular atrophy.</p
Size of <i>C9orf72</i> hexanucleotide repeats in CNS and WBC paired samples.
<p>WBC repeats were not tested when CNS repeats were less than 8 in number (except for 3 samples).</p>¶<p>and §: twins as well as CNS donor (see also <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0070007#pone-0070007-t002" target="_blank">Table 2</a>), NT: not tested.</p
Highly Efficient SO<sub>2</sub> Absorption and Its Subsequent Utilization by Weak Base/Polyethylene Glycol Binary System
A binary system consisting of polyethylene glycol (PEG,
proton
donor)/PEG-functionalized base with suitable basicity was developed
for efficient gas desulfurization (GDS) and can be regarded as an
alternative approach to circumvent the energy penalty problem in the
GDS process. High capacity for SO<sub>2</sub> capture up to 4.88 mol
of SO<sub>2</sub>/mol of base was achieved even under low partial
pressure of SO<sub>2</sub>. Furthermore, SO<sub>2</sub> desorption
runs smoothly under mild conditions (N<sub>2</sub>, 25 °C) and
no significant drop in SO<sub>2</sub> absorption was observed after
five-successive absorption–desorption cycles. On the other
hand, the absorbed SO<sub>2</sub> by PEG<sub>150</sub>MeIm/PEG<sub>150</sub>, being considered as the activated form of SO<sub>2</sub>, can be directly transformed into value-added chemicals under mild
conditions, thus eliminating the energy penalty for SO<sub>2</sub> desorption and simultaneously realizing recycle of the absorbents.
Thus, this SO<sub>2</sub> capture and utilization (SCU) process offers
an alternative way for GDS and potentially enables the SO<sub>2</sub> conversion from flue gas to useful chemicals as a value-added process
Early and late onset somatic mutations.
<p>In the human cell lineage, germline progenitor cells that produce the gametes (at the horizontal dashed line) are formed before the somatic cell lineages start dividing. The progenitor cells and their daughter cells for 4 somatic cell lines are shown. (A) Here a somatic mutation has occurred in a CNS progenitor cell, which is passed on to its daughter cells (red-filled circles) but which leaves the other cell lines intact. Comparing DNA from both the CNS and from white blood cells will reveal this somatic mutation. (B) The somatic mutation here has affected an early stem cell, so most or all of the somatic cell lines will contain the mutation. This mutation can be detected if one monozygous twin has a white blood cell mutation and the other does not.</p
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