28 research outputs found
Polyolefin Thermoplastics for Multiple Shape and Reversible Shape Memory
This
work reports the first pure hydrocarbon thermoplastic polyolefin
material with reversible shape memory effect under stress-free or
very small external loading condition. A thermoplastic ethylene/1-octene
diblock copolymer with designed chain microstructure was synthesized.
The polyolefin material performed not only the conventional one-way
multishape memory effects, but also a two-way reversible shape memory
effect (RSME). The elongation and contraction induced by oriented
crystallization with heating was confirmed as the mechanism of RSME
without chemical cross-linking. This work demonstrated that the thermoplastic
reversible shape memory could be achieved through careful design of
chain microstructure, based on sole hydrocarbon materials such as
ethylene-1-octene copolymer
Mechanical Force Sensitive Acrylic Latex Coating
We prepared force sensitive acrylic
latex coatings by covalently incorporating spiropyran mechanophore.
The acrylic latexes were obtained through emulsion copolymerization
of butyl acrylate (BA), methyl methacrylate (MMA) with vinylÂtriethoxysilane
(VTES) as interparticle cross-linker, and (1â˛-(2-(methacrylÂoyloxy)Âethyl)-3â˛,3â˛-dimethylÂspiroÂ[chromene-2,2â˛-indolin]-6-yl)Âmethyl
methacrylate) (SP) as intraparticle cross-linker. The latexes of PÂ(BA-<i>co</i>-MMA-<i>co</i>-SP-<i>co</i>-VTES)
were subsequently cast onto Teflon-coated surface to form latex coatings.
The condensation of hydrolyzed VTES provided interparticle cross-linking
and improved mechanical properties of the formed thin films. Intraparticle
cross-linker SP endowed the coatings with mechanoreponsiveness. The
mechanoactivation of SP-containing latex films was demonstrated. Increasing
the content of intra-cross-linker SP resulted in higher stress sensitivity
and lower critical stress required for mechanoactivation. Increasing
the content of interparticle cross-linker VTES resulted in higher
critical stress for SP mechanoactivation but had little effect on
the stress sensitivity. <i>T</i><sub>g</sub> and operation
temperature also showed significant effect on mechanoactivation. Slower
strain rate allowed for higher SP-to-MC conversion. This work represents
the first example of mechanochromic acrylic latexes and provides insight
into the design of force sensitive and self-reporting polymer coatings
Confusion matrix for CoTrade on the eight activity classes.
<p>The subfigures correspond to the performance of the algorithm using different numbers of labeled examples. The x- and y-coordinates are the class labels. (A) Confusion matrix obtained with 10% labeled examples. (B) Confusion matrix obtained with 20% labeled examples. (C) Confusion matrix obtained with 30% labeled examples. (D) Confusion matrix obtained with 40% labeled examples. (E) Confusion matrix obtained with 50% labeled examples.</p
Mean accuracy (MA) boxplots for the different co-training methods.
<p>Each subfigure corresponds to one case of labeled examples. (A) MA obtained using 10% labeled examples. (B) MA obtained using 20% labeled examples. (C) MA obtained using 30% labeled examples. (D) MA obtained using 40% labeled examples. (E) MA obtained using 50% labeled examples.</p
The accuracy of the different methods for the eight activity classes.
<p>Each subfigure corresponds to one activity class in the dataset. The x-coordinate is the number of labeled examples. (A) Parade. (B) Birthday party. (C) Graduation party. (D) Wedding reception. (E) Wedding dance. (F) Music performance. (G) Non-music performance. (H) Wedding ceremony.</p
A Novel Lignin/ZnO Hybrid Nanocomposite with Excellent UV-Absorption Ability and Its Application in Transparent Polyurethane Coating
In this work, lignin/zinc oxide nanocomposites
with excellent UV-absorbent
performance were prepared through a novel hydrothermal method using
industrial alkali lignin (AL) as raw materials. AL was first modified
by quaternization to synthesize quaternized alkali lignin (QAL). The
QAL/ZnO nanocomposites with different lignin contents were then prepared
via a facile one-step hydrothermal method using QAL and zinc nitrate
hexahydrate and hexamethylenetetramine in aqueous solution. The prepared
nanocomposite possessed an average diameter of âź100 nm and
showed excellent synergistic UV-absorbent performance. The particle
morphology and hybrid structure were carefully characterized by SEM,
TEM, XRD, FT-IR, XPS, UVâvis, and TG analyses. Interestingly,
it was found that the UV transmittance of polyurethane (PU) film was
significantly reduced and the mechanical properties of the PU were
significantly enhanced when blended with the prepared QAL/ZnO nanocomposite.
The results of this work were of practical importance for high value-added
application of industrial lignin in the field of functional materials
Confusion matrix for LapCo on the eight activity classes.
<p>The subfigures correspond to the performance of the algorithm using different numbers of labeled examples. The x- and y-coordinates are the class labels. (A) Confusion matrix obtained with 10% labeled examples. (B) Confusion matrix obtained with 20% labeled examples. (C) Confusion matrix obtained with 30% labeled examples. (D) Confusion matrix obtained with 40% labeled examples. (E) Confusion matrix obtained with 50% labeled examples.</p
Summary of the HesCo algorithm for co-training.
<p>Summary of the HesCo algorithm for co-training.</p
Engineering Pheromone-Mediated Quorum Sensing with Enhanced Response Output Increases Fucosyllactose Production in Saccharomyces cerevisiae
Engineering dynamic control of gene expression is desirable
because
many engineered functions interfere with endogenous cellular processes
that have evolved to facilitate growth and survival. Minimizing conflict
between growth and production phases can therefore improve product
titers in microbial cell factories. We developed an autoinduced gene
expression system by rewiring the Saccharomyces cerevisiae pheromone response pathway. To ameliorate growth reduction due to
the early onset response at low population densities, Îą-pheromone
of Kluyveromyces lactis (KÎą)
instead of S. cerevisiae (SÎą)
was expressed in mating type âaâ yeast. KÎą-induced
expression of pathway genes was further enhanced by the transcriptional
activator Gal4p expressed under the control of the pheromone-responsive FUS1 promoter (Pfus1). As a
demonstration, the engineered circuit combined with the deletion of
the endogenous galactose metabolic pathway genes was applied to the
production of human milk oligosaccharides, 2â˛-fucosyllactose
(2â˛-FL) and 3-fucosllactose (3-FL). The engineered strains
produced 3.37 g/L 2â˛-FL and 2.36 g/L 3-FL on glucose with a
volumetric productivity of 0.14 and 0.03 g/L¡hâ1 in batch flask cultivation, respectively. These represented 147
and 153% increases over the control strains on galactose wherein the
respective pathway genes are expressed under GAL promoters
only. Further fed-batch fermentation achieved titers of 32.05 and
20.91 g/L for 2Ⲡand 3-FL, respectively. The genetic program
developed here thus represents a promising option for implementing
dynamic regulation in yeast and could be used for the production of
biochemicals that may place a heavy metabolic burden on cell growth