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 vinyl­triethoxysilane (VTES) as interparticle cross-linker, and (1′-(2-(methacryl­oyloxy)­ethyl)-3′,3′-dimethyl­spiro­[chromene-2,2′-indolin]-6-yl)­methyl methacrylate) (SP) as intraparticle cross-linker. The latexes of P­(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>_g 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

List of important notations.

<p>List of important notations.</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

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

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 ∼100 nm and showed excellent synergistic UV-absorbent performance. The particle morphology and hybrid structure were carefully characterized by SEM, TEM, XRD, FT-IR, XPS, UV–vis, 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

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, α-pheromone of Kluyveromyces lactis (Kα) instead of S. cerevisiae (Sα) was expressed in mating type “a” yeast. Kα-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, 2′-fucosyllactose (2′-FL) and 3-fucosllactose (3-FL). The engineered strains produced 3.37 g/L 2′-FL and 2.36 g/L 3-FL on glucose with a volumetric productivity of 0.14 and 0.03 g/L·h–1 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 2′ and 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