Abstract
Our society is pursuing chemically recyclable polymers to accelerate the green revolution in plastics. Here, we develop a recyclable polyester library from the alternating copolymerization ...of aldehyde and cyclic anhydride. Although these two monomer sets have little or no thermodynamic driving force for homopolymerization, their copolymerization demonstrates the unexpected alternating characteristics. In addition to readily available monomers, the method is performed under mild conditions, uses common Lewis/Brønsted acids as catalysts, achieves the facile tuning of polyester structure using two distinct monomer sets, and yields 60 polyesters. Interestingly, the copolymerization exhibits the chemical reversibility attributed to its relatively low enthalpy, which makes the resulting polyesters perform closed-loop recycling to monomers at high temperatures. This study provides a modular, efficient, and facile synthesis of recyclable polyesters using sustainable monomers.
In conventional metallic materials, strength and ductility are mutually exclusive, referred to as strength-ductility trade-off. Here, we demonstrate an approach to improve the strength and ductility ...simultaneously by introducing micro-banding and the accumulation of a high density of dislocations in single-phase high-entropy alloys (HEAs). We prepare two compositions (Cr10Mn50Fe20Co10Ni10 and Cr10Mn10Fe60Co10Ni10) with distinctive different stacking fault energies (SFEs) as experimental materials. The strength and ductility of the Cr10Mn50Fe20Co10Ni10 HEA are improved concurrently by grain refinement from 347.5 ± 216.1 µm to 18.3 ± 9.3 µm. The ultimate tensile strength increases from 543 ± 4 MPa to 621 ± 8 MPa and the elongation to failure enhances from 43±2% to 55±1%. To reveal the underlying deformation mechanisms responsible for such a strength-ductility synergy, the microstructural evolution upon loading is investigated by electron microscopy techniques. The dominant deformation mechanism observed for the Cr10Mn50Fe20Co10Ni10 HEA is the activation of micro-bands, which act both as dislocation sources and dislocation barriers, eventually, leading to the formation of dislocation cell structures. By decreasing grain size, much finer dislocation cell structures develop, which are responsible for the improvement in work hardening rate at higher strains (>7%) and thus for the increase in both strength and ductility. In order to drive guidelines for designing advanced HEAs by tailoring their SFE and grain size, we compute the SFEs of Cr10MnxFe70–xCo10Ni10 (10 ≤ x ≤ 60) based on first principles calculations. Based on these results the overall changes on deformation mechanism can be explained by the influence of Mn on the SFE.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The mechanical behavior and deformation mechanisms of a body-centered cubic (BCC) Ti29Zr24Nb23Hf24 (at%) high entropy alloy (HEA) was investigated in temperatures and strain rates from 700° to ...1100 °C and 10−3 to 10 s−1, respectively. The HEA exhibits a substantial increase in yield stress with increasing strain rate. The strain rate sensitivity (SRS) coefficient is ~3 times that of BCC alloy Nb-1Zr and even ~3.5 times that of pure Nb. This high SRS is attributed to the high Peierls stress of the HEA, which is about twice the Peierls stress of pure Nb. On the other hand, the flow stress exhibits a tendency from strain softening to strain hardening with the increase of strain rate especially at the relatively low temperatures. This behavior is explained by a change in dislocation motion from climbing to multiple slip with the increase of strain rate. Taking the specimen subjected to 800 ºC for example, dislocation walls formed at the early stage of deformation and at low strain rate of 10−3 s−1. In this case there is sufficient time to activate dislocations climb, which results in discontinuous dynamic recrystallization, and strain softening. However, when the strain rate amounts to 1 s−1, thermally activated processes such as dislocation climb are too sluggish. As a consequence, multiple slip systems are activated, and the dislocation interactions lead to the evolution of deformation bands, leading to strain hardening.
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•Strain-rate dependent mechanical behavior of BCC Ti29Zr24Nb23Hf24 RHEA at elevated temperatures is revealed.•The effect of strain rate on the dynamic recrystallization of BCC RHEA is studied.•The effect of strain rate on the dislocation structure evolution of BCC RHEA is investigated.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
A novel multianalyte electrochemical immunosensor based on the assembly of patterned SWNTs on glassy carbon (GC) substrates was developed for simultaneous detection of endosulfan and paraoxon. Based ...on aryldiazonium salt chemistry, forest of SWNTs can be patterned on GC substrates by C3C bonding using micro contact printing (MCP), which provides an interface showing efficient electron transfer between biomolecules and electrodes. Then redox molecules FDMA and PQQ can be attached to the SWNTs, respectively followed by the attachment of specific epitopes and antibodies. The modified sensing surfaces were characterized by XPS, SEM, AFM and electrochemistry. Based on the current change of specific redox probes, the fabricated immunosensor array can be used for simultaneous detection of endosulfan and paraoxon by a displacement assay. In phosphate buffer solution (50mM, pH 7.0), there is a linear relationship between electrochemical signal of FDMA and the concentration of endosulfan over the range of 0.05–100ppb with a detection limit of 0.05ppb; the linear range between electrochemical signal of PQQ and the concentration of paraoxon is 2–2500ppb with a detection limit of 2ppb. The immunosensor array demonstrates high repeatability, reproducibility, stability and selectivity for the detection of endosulfan and paraoxon.
•A novel multianalyte electrochemical immunosensor based on the assembly of patterned SWNTs on GC substrates is presented.•Forest of SWNTs can be patterned on GC substrates by C3C bonding using micro contact printing (MCP).•The fabricated immunosensor can be used for simultaneous detection of endosulfan and paraoxon with high sensitivity.•The fabricated immunosensor array demonstrates high repeatability, reproducibility, stability and selectivity towards the pesticides detection.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The late Palaeozoic Yong’an–Meizhou depression belt is an important iron (Fe) and polymetallic metallogenic belt in southern China. It has undergone a transformation from Tethys to the circum-Pacific ...tectonic domain. The Luoyang deposit is one of the typical Fe skarn deposits in the Yong’an–Meizhou depression belt of eastern China. Garnet is a characteristic mineral in the deposit. Two generations of garnets are detected in the deposit based on their textural characteristics and trace-element contents, and are represented by Fe-enriched andradite. The first generation of garnets (Grt1) have two types of garnets (Grt1-A and Grt1-B). Type A garnets of the first generation (Grt1-A) (Adr80-88) replaced by massive diopside-magnetite assemblage exhibit distinct oscillatory zonings and display patterns of enriched light rare earth elements (LREE) to weak heavy rare earth elements (HREE), with weak negative to positive Eu anomalies, and highest U, ΣREE and Sn contents. Type B garnets of the first generation (Grt1-B) are irregular zones (Adr94-96) coexisting with magnetite, in which Grt1-A is generally dissolved, and have obviously LREE-enriched and HREE-depleted patterns, with weak negative to positive Eu anomalies, and moderate U, ΣREE and Zn contents. Garnets of the second generation (Grt2) (Adr96-99) that replaced massive magnetite together with sphalerite show unzoned patterns, with a flat REE pattern and pronounced negative Eu anomalies as well as contents of lowest U and ΣREE, and highest W. The substitution of REEs in garnets occurs as X2+VIII –1REE3+VIII +1Si4+IV –1Z3+IV +1in an Al-enriched environment. Luoyang hydrothermal fluids shifted from reducing conditions with relatively high-U and -ΣREE characteristics to oxidizing conditions with relatively low-U and -ΣREE characteristics. The reduced siderophile elements and increased fO2 in fluid during Grt1-B formation caused magnetite mineralization and reduced Zn contents during Grt2 formation, causing the deposition of sphalerite. All garnets formed from magmatic fluid and were controlled by infiltrative metasomatism in an opened system.
This work introduced an efficient approach for modification of AuNPs with multicomponents by diazonium salt couplings. The multifunctionalized AuNPs with protruding functional groups that allow ...simple bioconjugation to large amounts of biomolecules have been successfully used as electronic bridges and signal amplifiers for an electrochemical immunosensor towards the detection of BoNT/A. The one-step anchoring AuNPs strategy has greatly increased the efficiency for attachment of biomolecules and subsequently increased the sensitivity. Sensitivity was further amplified by preparation of bioconjugates particles containing horseradish peroxidase (HRP) labels along with detection antibodies (AbL) attached to AuNPs. The immunosensor can be used for the detection of BoNT/A over the range of 4–35pgmL−1 with the lowest detection limit of 1pgmL−1 and assay time of 10min. The herein sensing strategy is rapid, robust, selective, sensitive, and is promising for future fabrication of point-of-care devices.
•AuNPs can be covalently anchored to GC surfaces by one-step strategy.•AuNPs were used as both electronic bridges and signal amplifiers in an immunosensor.•The immunosensor can be used for detection of BoNT/A in both buffers and milks.•The detection limit of BoNT/A is 1pgmL−1 in buffer with the assay time of 10min.•The herein sensing strategy is promising for designing point-of-care devices.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
A biosensor based on AuNP modified GC electrodes has been developed for direct detection of methyl parathion. AuNP can be introduced to mixed monolayers of aryldiazonium salt modified GC electrodes ...by Au-C bonding through aryldiazonium salt chemistry, which provides a stable interface showing efficient electron transfer between biomolecules and electrodes. PEG molecules were introduced to the interface to resist non-specific protein adsorption. AuNP surfaces were further modified with 4-carboxyphenyl followed by covalent immobilization of methyl parathion hydrolase (MPH), a specific biocatalytic enzyme to methyl parathion. Exposure of this interface to methyl parathion resulted in a change in amperometric signal due to the MPH catalytic hydrolysis of methyl parathion producing electroactive compound 4-nitrophenol. This biosensor shows high selectivity, specificity, reproducibility and stability, and is functional for the detection of methyl parathion in real samples. The linear range for detection of methyl parathion is 0.2-100 ppb with a detection limit of 0.07 ppb in 0.1M phosphate buffer at pH 7.0.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The extensive amount of Satellite Image Time Series (SITS) data brings new opportunities and challenges for land cover analysis. Many supervised machine learning methods have been applied in SITS, ...but the labeled SITS samples are time- and effort-consuming to acquire. It is necessary to analyze SITS data with an unsupervised learning method. In this paper, we propose a new unsupervised learning method named Deep Temporal Iterative Clustering (DTIC) to deal with SITS data. The proposed method jointly learns a neural network’s parameters and the resulting features’ cluster assignments, which uses a standard clustering algorithm, K-means, to iteratively cluster the features produced by the feature extraction network and then uses the subsequent assignments as supervision to update the network’s weights. We apply DTIC to the unsupervised training of neural networks on both SITS datasets. Experimental results demonstrate that DTIC outperforms the state-of-the-art K-means clustering algorithm, which proves that the proposed approach successfully provides a novel idea for unsupervised training of SITS data.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
In this study, we investigated the expression and functions of long noncoding RNAs (LncRNAs) of LINC01518 in an in vitro model of TGF-β1-treated human Tenon capsule fibroblast (HTF) cells. qRT-PCR ...was used to examine LINC01518 expression in in situ human glaucoma tissues, and in vitro HTF cells treated with TGF-β1. Lentivirus-mediated LINC01518 knockdown was performed in HTF cells to investigate its effect on TGF-β1-induced cell proliferation, migration and autophagy signaling pathway. The potential ceRNA candidate of LINC01518, hsa-miR-216b-5p, was probed by dual-luciferase assay and qRT-PCR. Hsa-miR-216b-5p was also knocked down in LINC01518-downregulated HTF cells to investigate the function of this lncRNA-miRNA epigenetic axis in TGF-β1-treated HTF cells. LINC01518 was upregulated in human glaucoma tissues and cultured HTF cells. LINC01518 downregulation significantly suppressed TGF-β1-induced cell proliferation, migration and autophagy signaling pathway in HTF cells. Hsa-miR-216b-5p was confirmed to be a ceRNA target of LINC01518. Knocking down hsa-miR-216b-5p reversed the suppressing effects of LINC01518 downregulation in TGF-β1-treated HTF cells. Our study demonstrated that LINC01518 is a functional factor in regulating proliferation and migration in TGF-β1-treated HTF cells, and hsa-miR-216b -5p may also be involved. Targeting the epigenetic axis of LINC01518/hsa-miR-216b-5p may provide new insight into the pathological development of human glaucoma.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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