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The as-extruded Mg-10Al2Y master alloy was chosen as a novel grain refiner for as-cast Mg-3Y alloy. Contrast samples of cast Mg-3Y alloy added with pure Al and Mg-Zr master alloy grain refiners were prepared under the same conditions. In this study, the influence of addition amounts of Al2Y and holding time on grain refinement efficiency as well as tensile properties was investigated. And the grain refining ability of the Al2Y particles was systematically evaluated in terms of the addition amounts, number density of the Al2Y particles and holding time. The finest grains are achieved at 2 wt% Al2Y addition amount, which corresponds to number density of the polygonal Al2Y particles of 420–460 mm–2. The Mg-10Al2Y master alloy has significant refinement performance and no refining recession occurs at the holding time within 60 min, or the settling time up to 180 min. Grain refinement and the second phase strengthening of uniformly distributed Al2Y particles contribute to the simultaneous enhancement on both strength and elongation of Mg-3Y alloy.

Wearable and implantable pressure sensors are in great demand for personalized health monitoring. Pressure sensors with low operation voltage and low power-consumption are desired for energy-saving devices. Organic iontronic devices, such as organic electrochemical transistors (OECTs), have demonstrated great potential for low power-consumption bioelectronic sensing applications. The ability to conduct both electrons and ions, in addition to their low-operation voltage has enabled the widespread use of OECTs in different biosensing fields. However, despite these merits, OECTs have not been demonstrated for pressure sensing applications. This is because most OECTs are gated with aqueous electrolyte, which fails to respond to external pressure. Here, a low power-consumption iontronic pressure sensor is presented based on an OECT, in which an ionic hydrogel is used as a solid gating medium. The resultant iontronic device operated at voltages less than 1 V, with a power-consumption between ~ 101– $10^{3} \mu \text{W}$ , while maintaining a tunable sensitivity between 1 ~ 10 kPa−1. This work places OECTs on the frontline for developing low power-consumption iontronic pressure sensors and for biosensing applications.

We use coarse-grained molecular dynamics simulations to study the self-assembly behavior of polyoxometalate (POM) nanoparticles (NPs) decorated with mobile polymer ligands under melt conditions. We demonstrate that due to the mobile nature of the grafted ligands on the NP surface, NPs have the ability to expose a part of their surfaces, leading to a block-copolymer-like self-assembly behavior. The exposed NP surface serves as one block and the grafted ligand polymers as another. This system has a strong ability to self-assemble into long-range ordered structures such as block copolymers due to large incompatibility between POM and ligand polymers, i.e., POM NPs can form lamellar, cylindrical, and spherical structures, which are consistent with previous experimental results. More importantly, these ordered structures are on the sub-10 nm scale, which is an important requirement for many applications. At low graft density, we find a new inverse-cylindrical structure formation where polymers form cylinders and POMs form a continuous network structure. A full self-assembly phase diagram is constructed which illustrates rules to manipulate the self-assembly structures of NPs decorated with mobile polymer ligands. We hope that these computational results will be useful for the new design of nanostructures with improved optical or electronic functions.

Polyolefins with high molecular weight and broad molecular weight distribution have attracted great attention due to their ease of processing and wide applications. In this paper, methylene-bridged asymmetric disalicylaldimine ligands bearing phenylthio and alkylthio sidearms (4a–4c) were synthesized from methylene-bridged disalicylaldehyde that reacted successively with 2-phenylthio and 2-alkylthio anilines, which then directly coordinated with TiCl4 to afford asymmetric bis-salicylaldiminato binuclear titanium complexes 5a–5c in one step. The asymmetric complexes were detailedly characterized by FTIR, 1H NMR, 13C NMR, and elemental analysis. Under the activation of modified methylaluminoxane (MMAO), these asymmetric complexes displayed high activity over 106 g mol(Ti)−1 h−1 atm−1 for ethylene polymerization and copolymerization with 1-hexene or norbornene. Compared with the corresponding mononuclear complexes, the asymmetric binuclear catalysts showed higher catalytic activity (up to 2.29 × 106 g mol(Ti)−1 h−1 atm−1) for ethylene polymerization to produce higher molecular weight polyethylenes with much wider molecular weight distribution due to the presence of two different active centers. For ethylene polymerization and copolymerization with 1-hexene, the catalytic activity of binuclear 5a which carries phenylthio and methylthio sidearms and the properties of the obtained polyolefins were more similar to those of mononuclear 6b which bears a phenylthio sidearm, indicating that the phenylthio group exerted major influences. However, for ethylene/norbornene copolymerization, 5a showed an activity significantly higher than that of 6b, yet similar to that of mononuclear 6a which bears a methylthio sidearm, indicating that the methylthio sidearm in 5a played a major role in this case. A smaller sidearm in the ligand was more conducive to the polymerization reaction when large comonomers were involved, and a balance of the steric hindrance between the ligand and the comonomer might be needed for achieving high catalytic performance.

A mild, organophotoredox synthetic protocol for forming C(sp3) -S/Se bond by reacting widespread redox-active esters with thio/selenosulfonates has been developed. The power of the synthetic manifold is fueled by an unprecedented broad substrate scope and wide functional group tolerance.

In this work, 8mol% yttria-stabilized zirconia (8YSZ) ripple-shaped electrolytes have been prepared by digital light processing (DLP) 3D printing and their electrochemical performances have been investigated. The total conductivities of flat samples printed at different angles were tested firstly to confirm that there is no huge influence on the electrochemical performance from the printing itself. Then, by using ripple-shaped electrolytes, primary cells were assembled and their electrochemical performance were investigated. Compared with the reference flat cell, an improvement of ~32% was achieved in the power density for the same thickness of the electrolyte (~200 µm) at 800 °C.

Sulfomycins are sulfur-rich, ribosomally synthesized, and post-translationally modified peptides (RiPPs) that are characterized by a 35-membered macrocyclic ring system with a pyridine domain central to five azoles and additional dehydroamino acids. The pathway through which these large thiopeptide antibiotics are formed in

Quantum signal processing (QSP) is a powerful quantum algorithm to exactly implement matrix polynomials on quantum computers. Asymptotic analysis of quantum algorithms based on QSP has shown that asymptotically optimal results can in principle be obtained for a range of tasks, such as Hamiltonian simulation and the quantum linear system problem. A further benefit of QSP is that it uses a minimal number of ancilla qubits, which facilitates its implementation on near-to-intermediate term quantum architectures. However, there is so far no classically stable algorithm allowing computation of the phase factors that are needed to build QSP circuits. Existing methods require the usage of variable precision arithmetic and can only be applied to polynomials of relatively low degree. We present here an optimization based method that can accurately compute the phase factors using standard double precision arithmetic operations. We demonstrate the performance of this approach with applications to Hamiltonian simulation, eigenvalue filtering, and the quantum linear system problems. Our numerical results show that the optimization algorithm can find phase factors to accurately approximate polynomials of degree larger than $10,000$ with error below $10^{-12}$., 26 pages, 17 figures

Choosing an appropriate interlayer (IL) is still a crucial challenge for charge balance and exciton regulation in ultra-thin doping-free white organic light-emitting diodes (WOLEDs). Herein, for the first time, the blue thermally activated delayed fluorescence (TADF) 10, 10, 10-(4, 4, 4-Phosphoryltris (benzene-4, 1-diyl)) tris (10Hphenoxazine) (TPXZPO) was selected as the n-type inter-layer (IL) switch. The monochromatic and white light device achieved maximum external quantum efficiencies (EQE) of 24.47% and 14.96%, respectively. More importantly, all devices exhibited extremely low turn-on voltage and stable electroluminescent spectra, with CIE coordinates Δ (x, y) varying only by (0.01, 0.01) in the luminance range of 100 to 10,000 cd/m2. The results showed that new-type IL plays a crucial role in regulating charge and exciton distribution, which could effectively control of the emission zone and the triplet exciton density. This excellent performance demonstrates that the introduction of TADF IL is a promising prospect in the application of high-performance ultra-thin doping-free WOLEDs.

Besides enhancing thermoelectric performance of the existing thermoelectric materials, many efforts have been focused on the exploration of novel thermoelectric materials with potentially high performance typically. This is largely guided by the concept of the intrinsic low lattice thermal conductivity, which is arisen from various mechanisms, such as intrinsic vacancy, low sound velocity, complex crystal structure and lattice anharmonicity. Motivated by the inherent feature of highly disorder cations and intrinsic vacancies introducing strong lattice anharmonicity, this work focuses on a semiconducting compound, ZnIn2Se4, as a potential thermoelectric material. Pristine ZnIn2Se4 shows an n-type conduction and a low carrier concentration of 2.8 × 1018 cm−3. A lattice thermal conductivity as low as ∼0.9 W/m*K at high temperature is obtained, due to the additional phonon scattering by highly disorder cations and intrinsic vacancies. Thus, a peak zT of ∼0.23 is demonstrated in pristine ZnIn2Se4 even with the carrier concentration far deviating from the optimum. This work not only indicates this compound as a promising n-type thermoelectric material, but also provides a direction for enhancement of zT.

In order to improve the robustness of the energy management system (EMS) and avoid the influence of demand power on the design of EMS, a coupled power-voltage equilibrium strategy based on droop control (CPVE-DC) is proposed in this paper. Making use of the principal that the DC bus can directly reflect the changes of load power, the proposed strategy couples DC bus voltage with output powers through droop control to achieve self-equilibrium. The proposed EMS is applied into a hybrid tramway model configured with multiple proton exchange membrane fuel cell (PEMFC) systems, batteries and super capacitors (SCs). FC systems and SC systems are responsible for satisfying most of the demand power, therefore the CPVE-DC strategy generates FCs and SCs reference power through power-voltage droop control on the primary control. Then batteries supplement the rest part of load power and generate DC bus voltage reference value of the next sampling time. With the gambling between output power and DC bus voltage, the hybrid system achieves self-equilibrium and steps into steady operation by selecting appropriate droop coefficients. Then the secondary control of the proposed strategy allocates power between every single unit. In addition, a penalty coefficient is introduced to balance SOC of SCs. The proposed strategy is tested under a real drive cycle LF-LRV on RT-LAB platform. The results demonstrate that the proposed strategy can achieve self-equilibrium and is effective to allocate demand power among these power sources，achieve active control for the range of DC bus voltage and SOC consensus of SCs as well. In addition, some faults are simulated to verify the robustness of the proposed strategy and it turns out that the CPVE-DC strategy possesses higher robustness. Finally, the CPVE-DC strategy is compared with equivalent consumption minimization strategy (ECMS) and the results shows that the proposed strategy is able to get higher average efficiency and lower equivalent fuel consumption.

Benefited from hierarchical porous structure of Loofah sponge (LS) fibers, a 3D electrically and thermally conductive network structure termed conductive cellulose skeleton (Cellulose-RGO-TDI) was fabricated. In addition, PA6 molecular chains were covalently bonded with conductive cellulose skeleton by reaction between imino groups of PA6 and isocyanate groups of Cellulose-RGO-TDI. As a result, PA6/Cellulose-RGO-TDI nano-composite with high electrical and thermal conductivity was fabricated via reactive melt processing. Both RGO outside the fiber and RGO inside the 3D-bundled micro-channel work together to assemble omnibearing trans-scale conductive networks in the whole hierarchical porous structure of the cellulose skeleton. Finally, more integral conductive pathways are established by RGO along the cellulose fiber, which is more beneficial to transmission of charge carrier and phonons in the whole cellulose skeleton. Exfoliated RGO nano-sheets homogeneously dispersed between matrix and cellulose skeleton and a good interface forms, which promoted formation of electrically and thermally conductive network, resulting in the remarkably improved electrically conductivity of 5.8 × 10−1 S/m and thermally conductivity of 0.419 W m−1 K−1 of the composite with 1.2 vol% RGO loading.

The Fenton oxidation of nuclear grade cationic exchange resin was investigated in view of the effects of initial temperature, H2O2 dosage, catalyst type and concentration as well as initial pH. Initial temperature and H2O2 dosage exhibited a significant positive effect on the decomposition of cationic resins, whereas the initial pH showed a negative effect. Ferrous ions had higher catalytic ability than copper ions to the H2O2 activation for resin decomposition, and the best Fe2+ concentration was 0.3 M. Under the conditions of initial temperature of 75 °C, H2O2 dosage of 200 mL, Fe2+ concentration of 0.3 M and initial pH of 0.01, a weight reduction of 73% was achieved. The experimental results on Co-substituted mock samples indicated that the radionuclides loaded in the resins were concentrated in liquid residue. The decomposition of cationic resins followed the two-stage first-order kinetics that composed of a dissolution period of resin beads (first-stage) and a followed degradation stage of resin solution (second-stage). Combined with the UV–visible and infrared spectra and their corresponding density functional theory (DFT) calculations, the dissolution of resin beads was due to the desulfonation of the sulfonated aromatic rings and the oxidative fragmentation of the polymer backbone by hydroxyl radicals ( OH) formed in Fenton reactions. After the dissolution of resin beads, the oxidative degradation and mineralization process proceeded by the attack of OH mainly in aqueous medium.

The component identification of textile materials is critical for quality control and measurement in the textile field. A novel hyperspectral imaging method and the related identification model are proposed to classify single-component textiles. Firstly, the hyperspectral data of the single-component fabrics were processed to conduct dimensionality reduction based on locally linear embedding (LLE), principal component analysis (PCA), and locally preserving projection (LPP) algorithms. Moreover, the original data of 288 wavelengths from 920 nm to 2500 nm were compressed to keep the typical wavelength regions. After that, these data were imported into two classifiers (decision tree classifier and K nearest neighbor (KNN) classifier) for training, and an identification model based on these training data was developed for the sample classification. The experimental results showed that all the samples could be identified correctly by the established identification model. The recognition rate and the stability of the classifier based on LPP model and KNN classification algorithm were proved to have the highest accuracy in our research.

Although the hard template method is often employed to prepare N-doped mesoporous carbon(N-MC), the removal of the silica template commonly involves the use of highly toxic HF or repeated treatment with NaOH solution. Herein, we report a polyvinylidene fluoride-assisted one-step method for synthesis of N-MC, namely the silica-free N-MC can be prepared via temperature-programmed thermal treatment of a slurry obtained by dispersing nano-silica into a solution containing sucrose, urea, oxalic acid, polyvinylidene fluoride and dimethylacetamide. The resulting N-MC, which owns 3.47%(mass fraction) nitrogen and a surface area of 929 m2/g, is a highly suitable support of Pd catalyst used in hydrodechlorination of 2,4-dichlorophenol, with its performance being much better than those of MC and activated carbon. The excellent catalytic hydrodechlorination activity of the Pd/N-MC catalyst can be attributed to its strong metal-support interaction which results in a good Pd dispersion and high resistance to the growth of nanosized Pd under reaction conditions.

We review the motivation, goals, and achievements of the Photonic Integrated Networked Energy efficient datacenter (PINE) project, which is part of the Advanced Research Projects Agency–Energy (ARPA-E) ENergy-efficient Light-wave Integrated Technology Enabling Networks that Enhance Dataprocessing (ENLITENED) program. The PINE program leverages the unique features of photonic technologies to enable alternative mega-datacenters and high-performance computing (HPC) system architectures that deliver more substantial energy efficiency improvements than can be achieved through link energy efficiency alone. In phase 1 of the program, the PINE system architecture demonstrated an average factor of 2.2 × improvement in transactions/joule across a diverse set of HPC and datacenter applications. In phase 2, PINE will demonstrate an aggressive 1.0 pJ/bit total link budget with high-bandwidth-density dense wavelength-division multiplexing (DWDM) links to enable additional 2.5 × or more efficiency gains through deep resource disaggregation.

In this study, large-scale triaxial compression tests are conducted on gravelly soil material. The experimental investigation shows that gravelly soil exhibits complicated volume-dilatation/contraction behaviours that are dependent on stress level. To better describe the mechanical behaviours, an elastoplastic constitutive model is proposed within the frameworks of generalised plasticity and the critical state soil mechanics. An evolution equation of the void ratio is incorporated into the model to describe the effect of a relatively dense or loose state on the volume-change behaviours. The model has 10 material constants that could be determined using a few large-scale conventional triaxial tests. The model is then used to simulate the mechanical behaviours of gravelly soil. Comparisons between the numerical simulations and the test data show that the model is capable of capturing the mechanical behaviours of gravelly soil under various confining pressures. This research can be beneficial for understanding the mechanical behaviours of gravelly soils.

The Empoasca onukii (Hemiptera: Cicadellidae) female lays its eggs inside the epidermis of the tea plant shoots. This has led to speculation that shoot harvesting could represent a method of egg removal. To verify the validity of this hypothesis, we sought to determine which part of the shoot was used for the oviposition and how the value of the harvested shoot affects the cost of the egg removal. In this study, four tea cultivars were chosen to examine the preferences for the site of oviposition. In addition, a mathematical model was used to describe the correlation between the economic value of the selected shoot and eggs laid within the shoot. Our study revealed that the pest preferred the 3rd and 4th leaf order intervals of the shoot as the oviposition sites, and the oviposition preferences was dependent on the leaf order interval class across all tea cultivars. In addition, a significant negative exponential relationship was found between the economic value of the selected shoot and the percentage of the eggs laid within the shoot, indicating that egg removal through shoot harvesting was limited. The findings of this study could be used to better understand the role of shoot harvesting in egg removal and would provide new insights into the understanding of the incidence of this pest.

We study the interfacial structure and dynamics of a polymer nanocomposite (PNC) composed of octaaminophenyl polyhedral oligomeric silsesquioxane (OAPS) and poly(2-vinylpyridine) (P2VP) by performing full atomistic molecular dynamics simulations. There are eight aminophenyl groups grafted on the surface of the OAPS particle and the particle has a size comparable to the Kuhn segment of P2VP. These aminophenyl groups can form hydrogen bonds (HBs) with pyridine rings from surrounding P2VP chains. We found that OAPS can form ∼2 HBs on average with surrounding polymer chains. The effect of the HBs is investigated in detail by either switching on or off these HBs in our simulation. By analyzing the interfacial static packing structure and dynamic properties, we demonstrate that the system has an ∼1 nm interface width, similar to the OAPS particle size. We also found that HBs can prevent the further penetration of polymers into the inner zone (grafting layer) of the OAPS, and therefore keep the P2VP chains in the outer layer (>1 nm), remaining bulk-like, which is well consistent with experimental results. In addition, we found that NP diffusion is coupled to the absorbed polymer chains, which also dramatically slows down the diffusion of polymer segments in return. The core–shell model in which the NP and absorbed polymers diffuse as a single object is validated here at the full atomistic level. These results provide atomistic insights into the unique structure and dynamics in the small attractive NP–polymer interfacial region. We hope these results will be helpful for the understanding of peculiar phenomena in attractive polymer nanocomposites containing small NPs.

We presented new physical insights into designing resonator-assisted photonic interleavers. The robust flat-top transmission spectra of the devices can be achieved and interpreted through rigorous mathematical models based on quasi Fourier series.

The combination of biomimetic nanochannels and nanostructures provided a new idea for bioanalytical purposes. In this paper, we reported a self-assembled system based on the integration of anodic aluminum oxide (AAO) membranes and CuO method to fabricate CuO nanostructures in the confined area of AAO membranes. Furthermore, we investigated morphologies of the self-assembly systems by field emission scanning electron microscopy (FESEM) and characterized the type and content of microelements by energy dispersive spectrometer. Transmembrane ion current through nanochannels was tested by an electrochemical workstation, and optical properties of the self-assembly systems were characterized by ultraviolet–visible spectrophotometer. We could conclude from the results that the morphology and distribution status of CuO nanostructures are controllable, while ionic current through nanochannels and optical properties of self-assembled systems could be regulated by changing experimental parameters such as electrodeposition time, electrodeposition voltage or annealing temperature. On this base, we utilized the synergistic effect of nanochannels and nanostructures to enhance the sensitivity of biological molecules response. This study not only prepared CuO nanostructures in biomimetic nanochannels controllably, but also provided a novel application paradigm for nanochannels-nanostructures self-assembled system, which could be used for biological analysis and detection.

Adding small nanoparticles (NPs) into polymer melt can lead to a non-Einstein-like decrease in viscosity. However, the underlying mechanism remains a long-standing unsolved puzzle. Here, for an all-polymer nanocomposite formed by linear polystyrene (PS) chains and PS single-chain nanoparticles (SCNPs), we perform large-scale molecular dynamics simulations and experimental rheology measurements. We show that with a fixed (small) loading of the SCNP, viscosity reduction (VR) effect can be largely amplified with an increase in matrix chain length \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$N$$\end{document}N, and that the system with longer polymer chains will have a larger VR. We demonstrate that such \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$N$$\end{document}N-dependent VR can be attributed to the friction reduction experienced by polymer segment blobs which have similar size and interact directly with these SCNPs. A theoretical model is proposed based on the tube model. We demonstrate that it can well describe the friction reduction experienced by melt polymers and the VR effect in these composite systems., Addition of small nanoparticles into polymer melt can lead to decrease in viscosity but the underlying mechanism for such viscosity reduction remains unclear. Here, the authors investigate the reduction in viscosity by large-scale molecular dynamics simulation and experimental rheology measurements for an all-polymer nanocomposite formed by linear polystyrene chains and PS single-chain nanoparticle.

The Chinese citrus fly, Bactrocera minax (Enderlein) (Diptera: Tephritidae), is the most destructive pest in many citrus orchards of south central China. Methyl eugenol and cuelure, 2 potent male lures that are effective for capturing related species, are believed not to attract this species. Limited knowledge is available about the effectiveness of attractant traps for this pest. A field trial was carried out to determine the efficacy of 8 attractant traps to B. minax. The study was conducted during the adult occurrence season in an orchard of navel orange, Citrus sinensis (L.) Osbeck (Rutaceae), in Zhijiang County, Hunan Province, China, in 2016. To link the efficacy of these attractant traps with the pest population, fruit infestations in the orchard also were investigated. As expected, this study confirmed that methyl eugenol and cuelure were not attractive to B. minax. Green-colored sticky spheres trapped significantly more flies and males than methyl eugenol and cuelure-baited traps. On average, ammonium acetate putrescine trapped more females than males, but it was not statistically better than any of the other tested attractant traps. Fruit infestation rates by B. minax ranged from 0.7 to 11.1% in the replicates. Judging by the results of trapping and actual field infestation, it appears that trap effectiveness of the 8 attractant traps was low. A more potent attractant trap is needed, especially for early detection of the pest.

The development of a general catalytic method for the direct and stereoselective construction of cyclopropanes bearing highly congested vicinal all-carbon quaternary stereocenters remains a formidable challenge in chemical synthesis. Here, we report an intramolecular radical cyclopropanation of unactivated alkenes with simple α-methylene group of aldehydes as C1 source via a Cu(I)/secondary amine cooperative catalyst, which enables the single-step construction of bicyclo[3.1.0]hexane skeletons with excellent efficiency, broad substrate scope covering various terminal, internal alkenes as well as diverse (hetero)aromatic, alkenyl, alkyl-substituted geminal alkenes. Moreover, this reaction has been successfully realized to an asymmetric transformation, providing an attractive approach for the construction of enantioenriched bicyclo[3.1.0]hexanes bearing two crucial vicinal all-carbon quaternary stereocenters with good to excellent enantioselectivity. The utility of this method is illustrated by facile transformations of the products into various useful chiral synthetic intermediates. Preliminary mechanistic studies support a stepwise radical process for this formal [2 + 1] cycloaddition., Synthesis of cyclopropanes bearing vicinal all-carbon quaternary stereocenters poses synthetic challenges. Here, the authors report an intramolecular radical cyclopropanation with a copper/amine cooperative catalytic system for the efficient construction of bicyclo[3.1.0]hexane skeletons, also enantioselectively.

Exploration of novel thermoelectric materials is of great significance for thermoelectric development. AB2X2 Zintl compounds with rich chemical constitute, have been frequently demonstrated as promising thermoelectric materials because of their low lattice thermal conductivity and tunable band structure. This motivates the current work to focus on the experimental evaluation of thermoelectric potential on SrCd2Sb2, a new member of Zintl compounds. Na-substitution at Sr site leads to an effective increase in Hall carrier concentration from ~ 2.6 × 1018 to ~ 1.1 × 1020 cm−3, enabling a well estimation of transport properties by a single parabolic band (SPB) model with acoustic scattering. This reveals a multi-band transporting behavior in SrCd2Sb2 thermoelectrics with heavy-doping or elevated-temperature, ensuring a 150%-improvement in thermoelectric figure of merit (zT). On the basis of model, a peak zT of ~ 1.4 is achievable by minimizing lattice thermal conductivity, which not only demonstrates this compound as a promising thermoelectric material, but also provides a guidance for further advancements.

Recently, our groups have introduced the notion of optical parametric amplification based on non-Hermitian phase matching wherein the incorporation of loss can lead to gain in this nonlinear optical process. Previous simulation results using second-order nonlinear optical coupled-mode theory have demonstrated the potential of this technique as an alternative to the stringent phase-matching condition, which is often difficult to achieve in semiconductor platforms. Here we fortify this notion for the case of third-order nonlinearity by considering parametric amplification in silicon nanowires and illustrate the feasibility of these devices by employing rigorous finite-difference time-domain analysis using realistic materials and geometric parameters. Particularly, we demonstrate that by systematic control of the optical loss of the idler in a four-wave mixing process, we can achieve efficient unidirectional energy conversion from the pump to the signal component even when the typical phase-matching condition is violated. Importantly, our simulations show that a signal gain of ∼ 9 d B for a waveguide length of a few millimeters is possible over a large bandwidth of several hundreds of nanometers ( ∼ 600 n m ). This bandwidth is nearly 2 orders of magnitude larger than what can be achieved in the conventional silicon-photonics-based four-wave mixing process.

We have demonstrated a low threshold and tunable flexible random laser (RL) in dye-doped poly ethylene glycol diacrylate (PEG-DA) hydrogel, which was prepared by crosslinking polymerization using PEG-DA monomer and photoinitiator. The random lasering is attributed to the light scattering from the porous structure of hydrogels, and the wavelength of random lasing can be tuned by ~3.2 nm in the temperature range from 30 °C to 70 °C. Under the continuous increasing and decreasing temperature cycle, the random lasing tunable phenomenon can still be observed, which proves that this flexible material can be used as a new temperature sensor. In addition, we also explored the application of flexible laser in phototherapy. Considering the good elasticity and transparency of hydrogels, this thermo-responsive property will be of great significance to the biomedical applications of flexible material.

Spent resins generated from the nuclear industrial processes are still difficult to be treated and disposed. Fenton-like processes have great application potential in the treatment of spent resins, but the Fenton reaction mechanisms and resin degradation pathways remain challenging. In this study, nanoscale Fe0/Cu0 bimetallic catalysts were prepared and characterized for the Fenton-like degradation of the mixture of cationic and anionic resins. High catalytic property of Fe0/Cu0 bimetallic nanoparticles activated by H2O2 was evaluated, according to the effects of various nanoparticles, temperature, catalyst amount, H2O2 concentration and the mixing ratio of cationic and anionic resins. Combined the shape and color changes of mixed resins with the experimental and calculated characterization results, different degradation difficulty of cationic and anionic resins and their degradation mechanisms were studied. According to the density functional theory calculations of the optimized resin molecules with the Fe0/Cu0 catalyst, the mechanisms of Fenton-like reactions and the degradation of mixed resins through the synergistic effect of Fe and Cu species were proposed. The comprehensive Fenton-like reactions and degradation mechanisms provide new insights to advance the treatment of spent resins and organic polymers by Fenton-like processes.

We have specified the synthetic conditions to obtain one-directionally ordered CaSi2 microwall arrays vertically grown on a Si substrate. Our basic concept is based on the utilization of the Kirkendall effect for reactive deposition epitaxy (RDE). We found for the first time that: 1) a much larger Ca vapor supply on the Si substrate than the conventional RDE, 2) the adoption of a two-step heating process, and 3) the selection of the crystal axis of the Si surface are the keys to control the microstructures of CaSi2 on the Si substrate. The CaSi phase was first formed on Si, then the CaSi2 phase was formed at the CaSi/Si interface. Based on the Kirkendall effect, the interdiffusion of Ca and Si was enhanced in the vertical direction rather than in the parallel direction to the Si surface. CaSi2 tends to grow along four equivalent Si{111} planes, however, the specific orientation of the Si surface resulted in CaSi2 microwalls grown along its Si(111‾ ) plane, the only plane directing nearly vertical to the surface among the Si{111} planes. These results suggest that the Kirkendall effect under asymmetric growth of target materials would be a rational strategy to obtain their ordered microstructures.

Nanoscale zero-valent iron (nZVI) was prepared and used as a heterogeneous Fenton-like catalyst for the degradation of nuclear-grade cationic exchange resin. The properties of nZVI before and after reaction were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Brunauer–Emmett–Teller (BET) surface area analysis. The results showed that nZVI–H2O2 system exhibited the enhanced degradation of cationic resins, compared with Fe2+–H2O2, Cu0–H2O2, and Fe0/Cu0–H2O2 systems. The effects of initial temperature, nZVI dose, and H2O2 concentration were studied, and the higher temperature and nZVI dose with relatively low H2O2 concentration brought faster degradation rate. The degradation of cationic resins followed the pseudo-first-order kinetics with the apparent activation energy of 53.29 kJ/mol. According to the experimental and calculated infrared and UV-visible spectra, the carbon skeleton of cationic resins was broken with the detachment of benzene ring and the desulfonation of resin polymer by hydroxyl radicals (•OH), generating long-chain alkenes. These intermediates were further oxidized through the hydroxyl substitution, hydrogen abstraction, ring cleavage, or carbonylation reactions, finally forming carboxylic acids remained in solution.

Rhombohedral GeTe can be approximated as the directional distortion of the cubic GeTe along [111]. Such a symmetry-breaking of the crystal structure results in an opposite arrangement in energy of the L and Σ valence bands, and a split of them into 3L+1Z and 6Σ+6η, respectively. This enables a manipulation of the overall band degeneracy for thermoelectric enhancements through a precise control of the degree of crystal structure deviating from a cubic structure for the alignment of the split bands. Here, we show the effect of AgBiSe2-alloying on the crystal structure as well as thermoelectric transport properties of rhombohedral GeTe. AgBiSe2-alloying is found to not only finely manipulate the crystal structure for band convergence and thereby an increased band degeneracy, but also flatten the valence band for an increased band effective mass. Both of them result in an increased density of state effective mass and therefore an enhanced Seebeck coefficient along with a decreased mobility. Moreover, a remarkably reduced lattice thermal conductivity of ∼0.4 W/m-K is obtained due to the introduced additional point defect phonon scattering and bond softening by the alloying. With the help of Bi-doping at the Ge site for further optimizing the carrier concentration, thermoelectric figure of merit, zT, of ∼1.7 and average zTave of ∼0.9 are achieved in 5% AgBiSe2-alloyed rhombohedral GeTe, which demonstrates this material as a promising candidate for low-temperature thermoelectric applications.

Made available in DSpace on 2019-10-04T12:38:12Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-07-24 NSERC DG MESI PSIIRI 936 China Scholarship Council Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Trottier Energy Institute FRQNT-RQMP Ion-gated transistors employ ionic gating media (e.g. ionic liquids, polymer electrolytes, aqueous saline solutions) to modulate the density of the charge carriers in the transistor channel. Not only they operate at low voltages (ca 0.5-1 V) but they can also feature printability, flexibility and easy integration with chemo- and bio-sensing platforms. Metal oxides are transistor channel materials interesting for their processability in air, at low temperature. Among metal oxides, tungsten oxide (band gap ca 2.5-2.7 eV) stands out for its electrochromic, gas sensing and photocatalytic properties. Here we demonstrate ion-gated tungsten oxide transistors and phototransistors working in different ion gating media, such as one hydrophobic ionic liquid and an aqueous electrolyte, fabricated both on rigid and flexible substrates. Ion-gated tungsten oxide phototransistors operating in aqueous media could be used as photocatalytic sensors in portable applications. Polytech Montreal, Dept Genie Phys, CP 6079,Succ Ctr Ville, Montreal, PQ H3C 3A7, Canada Univ Fed Minas Gerais, Dept Fis, BR-30123970 Belo Horizonte, MG, Brazil Polytech Montreal, Dept Genie Chim, CP 6079,Succ Ctr Ville, Montreal, PQ H3C 3A7, Canada Univ Estadual Paulista, Dept Fis Quim, Rua Prof Degni 55, BR-14800060 Araraquara, Brazil Univ Montreal, Dept Chim, CP 6128,Succ Ctr Ville, Montreal, PQ H3C 3J7, Canada Univ Bologna, Dipartimento Chim Giacomo Ciamician, Via Selmi 2, I-40126 Bologna, Italy Univ Estadual Paulista, Dept Fis Quim, Rua Prof Degni 55, BR-14800060 Araraquara, Brazil FAPESP: 2014/27079-9 FAPESP: 2015/50526-4 FAPESP: 2016/09033-7

There is an increasing need to develop conducting hydrogels for bioelectronic applications. In particular, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) hydrogels have become a research hotspot due to their excellent biocompatibility and stability. However, injectable PEDOT:PSS hydrogels have been rarely reported. Such syringe-injectable hydrogels are highly desirable for minimally invasive biomedical therapeutics. Here, an approach is demonstrated to develop injectable PEDOT:PSS hydrogels by taking advantage of the room-temperature gelation property of PEDOT:PSS. These PEDOT:PSS hydrogels form spontaneously after syringe injection of the PEDOT:PSS suspension into the desired location, without the need of any additional treatments. A facile strategy is also presented for large-scale production of injectable PEDOT:PSS hydrogel fibers at room temperature. Finally, it is demonstrated that these room-temperature-formed PEDOT:PSS hydrogels (RT-PEDOT:PSS hydrogel) and hydrogel fibers can be used for the development of soft and self-healable hydrogel bioelectronic devices.

Nitrogen/phosphorus enriched biochars with enhanced porosity were prepared through a one-step pyrolysis of bamboo sawdust activated by guanidine phosphate (GP). The thermal decomposition of GP released alkaline gas and hydrogen proton to create more micropores in biochar matrix which were extended to be mesopores further. Nitrogenous/phosphorous moieties of GP were introduced into biochars efficiently via cross-linking with the carbon skeleton. GP-activated biochar pyrolyzed at 450 °C exhibited enriched surface functional groups (11.3 at.% for N, 4.1 at.% for P), resulting in high sorption capacities for aquatic Pb(II) (166.2 mg/g), Cu(II) (81.7 mg/g), and Cd(II) (60.3 mg/g). Pb(II) was passivated fast with the formation of minerals including Pb5(PO4)3OH and Pb5(PO4)3Cl. Cu(II) was strongly coordinated with the N-containing species especially pyridinic N. Cd(II) was also captured efficiently due to the chemical complexation, cation exchange and cation-π bonds. GP-activated biochars could be well-recycling used to capture these heavy metals. Regarding these, the activation of biomass residuals could be an efficient approach to functionalize the surface of biochars with enhanced porosity, which is great benefiting for the immobilization of heavy metals from contaminated water.

The regulation of charge and exciton distribution play a significant role in ultra-thin non-doped white organic light-emitting diodes (WOLEDs). Herein, the exciplex is selected as an interlayer (IL) switch to adjust the charge balance and regulate exciton distribution in ultra-thin non-doped WOLEDs. The optimal device achieved a maximum external quantum efficiency (EQE) of 22.42 %, a maximum current efficiency of 63.41 cd/A and a maximum power efficiency of 83.04 lm/W. The time‐resolved photoluminescence of different exciplexes has been systematically investigated to reveal the intrinsic luminance mechanism of high-efficiency WOLEDs. In addition, kelvin probe force microscopy (KFPM) results provide new insights in exciplex interlayer switch surface charge effect. These results demonstrate the potential of exciplex IL for exciton confinement, charge balance and carrier transport, which prevent energy loss and reduce triplet-triplet annihilation. Therefore, the utilization of exciplex IL is a promising approach for the development of next-generation WOLEDs.

Ensuring stable red and blue emission from white organic light-emitting devices (WOLEDs) with complementary colors is a major challenge. Here, a novel exciplex systems were used to solve this problem, where a thermally activated delayed fluorescence (TADF) material 10, 10, 10-(4, 4, 4-Phosphoryltris (benzene-4,1-diyl)) tris (10Hphenoxazine) (TPXZPO) and a common hole transporting material N,N′-dicarbazolyl-3,5-benzene (MCP) were mixed with an electron-transporting material (1,3,5-Triazine-2,4,6-triyl)tris(benzene-3,1-diyl)) tris(diphenylphosphineoxide) (PO-T2T) to form exciplex host for red and blue phosphorescent materials, respectively. Benefitted from the high triplet energy of donor and accepter were select to form exciplex host which ensures that excitons are excellent confined to the EMLs. Matched exciplex host-guest systems and a multichannel reverse intersystem crossing reduces energy loss during energy transfer processes and prevents triplet-triplet annihilation. The use of stepped energy transfer channels and exciplex interlayer switch ensures WOLEDs have greater stability. The devices exhibited a maximum power efficiency, current efficiency, and external quantum efficiency of 69.25 lm/W, 56.69 cd/A and 24.55%, respectively. More importantly, the devices exhibited extremely stable color rendering index ranging from 74 to 76 with luminance ranging from 102 to 104 cd/m2. These results indicate that the exciplex are promising for use in developing high performance complementary color WOLEDs.

Selection of non-toxic elements existed in human body or certified for tissue regeneration is considered for multifunctional biodegradable metals. The effect of Sr addition on microstructure, mechanical properties, and degradation behavior of biodegradable Mg–2Zn-0.3Ca alloy was studied as an example to gain insight into the Mg–Zn–Ca alloy series. The average grain size of alloys became smaller and more homogeneous distinctly by increasing Sr content. The second phases on the grain boundaries and the interdendritic interstices were also refined with small amount of Sr addition. More concentration of Sr element was detected evidentially at the interface between grains and the second phases. Mg–2Zn-0.3Ca-0.3Sr alloy shows the optimal flexural and compressive strength of (441 ± 18) MPa and (317 ± 13) MPa, respectively. The electrochemical measurement in simulated body fluid showed that addition of Sr would slightly deteriorate the corrosion resistance of Mg–Zn–Ca–Sr alloys. The in-vitro immersion tests were conducted and analyzed in detail by three different immersion stages and got a distinctive corrosion performance compared with the electrochemical measurements. Homogenization annealing was conducted for Mg–2Zn-0.3Ca-0.3Sr alloy, which can reduce dendrite segregation and significantly improve the corrosion resistance of alloy. The degradation process of alloys in simulated body fluid was summarized in detail for Mg–Zn–Ca–Sr alloys. This work not only provides the relationship between microstructure and properties of biodegradable Mg alloys, but also a comprehensive discussion of degradation behavior of Mg–Zn–Ca alloys for orthopedic application.

Si nanosheets connected to Si nanowires were synthesized using a MnCl 2 /Si powder source with an Au catalyst. The synthesis method has benefits in terms of avoiding conventionally used air-sensitive SiH 4 or SiCl 4 . The existence of the Si nanosheets connected to the Si nanowires, like sprouts or leaves with petioles, was observed, and the surface of the nanosheets was Si{111}. The nanosheets were grown in the growth direction of perpendicular to that of the Si nanowires. It was evident from these structural features of the nanosheets that the nanosheets were formed by the twin-plane reentrant-edge mechanism. The feature of the observed lattice fringes, which do not appear for Si bulk crystals, of the Si(111) nanosheets obtained by high resolution transmission electron microscopy was clearly explained due to the extra diffraction spots that arose by the reciprocal lattice streaking effect.

Structural control and morphological modification of a series of Si-based nanostructures were studied from the viewpoint of modifying the catalyst’s characteristics. The catalyst was modified from a liquid to a solid during its growth. The growth evolution of the faceted Si nanowires occurred via a vapor–liquid–solid mechanism followed by a silicide vapor–solid–solid mechanism. The shapes of the catalysts defined the shapes of the nanowires during the vapor–solid–solid growth. The catalyst was further modified by the deposition of MnCl2. Only irregularly shaped Si particles or MnCl2 particles were observed on top of the Si nanowires. The characteristic modification of catalysts by liquid-phase crystal nucleation and deposition of liquid-phase droplets was discussed. In addition, the synthesis of a CrSi2 nanowire bundle by the formation of dense nanoparticles was studied.

Hybrid organic–inorganic perovskites, represented by materials in the CH3NH3PbI3 series, have become one of the most promising materials for solar cells with a high power conversion efficiency and low cost. The ordered Pb–I cage in such hybrid perovskites can induce the polarized cations to form a variety of polarization domains with long-range order, which will lead to the formation of specific atomic conformations or metastable crystalline phases, unique electronic band structures and optical absorption properties. Such domain-dependent characteristics play a critical role in the phase transition and service stability of such solar cells, and also open up the opportunity of tuning their electronic structure. In the present study, we systematically investigate the band structures and optical absorption properties of different electronically ordered domains in CH3NH3PbI3. By comparing different perovskites containing various cations, we have clarified the important influence of cation polarization on domain-dependent properties. Our results provide not only a possible pathway for the manipulation of band structure by applying an external field, but also a novel scheme for improving the performance and stability of hybrid perovskites.

Forest degradation has been considered as one of the main causes of climate change in recent years. The knowledge of estimating degraded forest areas without the application of remote sensing tools can be useful in finding solutions to resolve degradation problems through appropriate restoration methods. Using the existing knowledge through literature review and field-based primary information, we generated new knowledge by combining the information obtained from multi-criteria decision analyses with an analytic hierarchy process, and this was then used to estimate degraded forest area. Estimation involves determining forest degradation index (FDI) and degradation threshold. Continuous inventory data of permanent sample plots collected from degraded forests, consisting of various forest types divided by dominant tree species in the Guangdong province and Tibet autonomous region of China, were used for the purposes. We identified four different forest degradation levels through the determination and comprehensive evaluation of FDI. The degraded forest area with broad-leaved species as dominant tree species in the Guangdong province was estimated to be 83.3% of a total forest area of 24,037 km2. In the same province, the degraded forest area with eucalyptus as a dominant tree species was 59.5% of a total forest area of 18,665 km2. In the Tibet autonomous region, the degraded forest area with spruce as a dominant tree species was 99.1% of a total forest area of 17,614 km2, and with fir as a dominant tree species, the degraded area was 98.4% of a forest area of 12,103 km2. A sampling accuracy of forest areas with national forest inventory was about 95% in both provinces. Our study concludes that the FDI method used has a certain scientific rationality in estimating degraded forest area. The forest provides a variety of tangible and intangible goods and services for humans. Therefore, forest management should focus on the improvement of its overall productivity, which is only possible with improving forest site quality. One of the important steps to improve the quality of a forest site is to resolve its degradation issues. The presented method in this article will be useful in finding the solutions to forest degradation problems. This method, which does not need any remote sensing tool, is simple and can be easily applied for estimating any degraded forest area and developing effective forest restoration plans.

Sulfomycins are sulfur-rich, ribosomally synthesized, and post-translationally modified peptides (RiPPs) that are characterized by a 35-membered macrocyclic ring system with a pyridine domain centr...

Polymeric single-chain nanoparticles (SCNPs) are soft nano-objects synthesized by intramolecular crosslinking of isolated single polymer chains. Syntheses of such SCNPs usually need to be performed in a dilute solution. In such a condition, the bonding probability of the two active crosslinking units at a short contour distance along the chain backbone is much higher than those which are far away from each other. Such a reaction condition often results in local spheroidization and, therefore, the formation of loosely packed structures. How to inhibit the local spheroidization and improve the compactness of SCNPs is thus a major challenge for the syntheses of SCNPs. In this study, computer simulations are performed and the fact that a precollapse of the polymer chain conformation in a cosolvent condition can largely improve the probability of the crosslinking reactions at large contour distances is demonstrated, favoring the formations of closely packed globular structures. As a result, the formed SCNPs can be more spherical and have higher compactness than those fabricated in ultradilute good solvent solution in a conventional way. It is believed this simulation work can provide a insight into the effective syntheses of SCNPs with spherical conformations and high compactness.

The diffusion dynamics of fullerene (C 60 ) in unentangled linear atactic polystyrene (PS) and polypropylene (PP) melts and the structure and dynamic properties of polymers in interface area are investigated by performing all-atom molecular dynamics simulations. The comparison of the results in two systems emphasises the influence of local interactions exerted by polymer side group on the diffusion dynamics of the nanoparticle. In the normal diffusive regime at long time scales, the displacement distribution function (DDF) follows a Gaussian distribution in PP system, indicating a normal diffusion of C 60 . However, we observe multiple peaks in the DDF curve for C 60 diffusing in PS melt, which indicates a diffusion mechanism of hopping of C 60 . The attractive interaction between C 60 and phenyl ring side groups are found to be responsible for the observed hopping diffusion. In addition, we find that the C 60 is dynamically coupled with a subsection of a tetramer on PS chain, which has a similar size with C 60 . The phenyl ring on PS chain backbone tends to have a parallel configuration in the vicinity of C 60 surface, therefore neighbouring phenyl rings can form chelation effect on the C 60 surface. Consequently, the rotational dynamics of phenyl ring and the translational diffusion of styrene monomers are found to be slowed down in this interface area. We hope our results can be helpful for understanding of the influence of the local interactions on the nanoparticle diffusion dynamics and interfacial properties in polymer/nanoparticle composites.

A copper-catalyzed asymmetric radical oxytrifluoromethylation of alkenyl oxime and Togni's reagent has been successfully developed, thereby providing straightforward access to CF3 -containing isoxazolines bearing α-tertiary stereocenters with excellent yield and enantioselectivity. The key to success is the rational design of cinchona-alkaloid-based sulfonamides as neutral/anionic hybrid ligands to effectively control the stereochemistry in copper-catalyzed reactions involving free alkyl radical species. The utility of this method is illustrated by efficient transformation of the products into useful chiral CF3 -containing 1,3-aminoalcohols.

Electrolyte-gated transistors hold promise for applications in printable and flexible electronics. Metal oxide semiconductors are particularly interesting as electrolyte-gated channel materials for their abundance, thermodynamic stability and ease of processing under ambient conditions. In this work, we synthesized by sol–gel and hydrothermal methods different types of tungsten oxide to be used as channel materials in ion gel-gated transistors. X-ray diffraction and scanning and transmission electron microscopy revealed that the differently processed oxides show a different structure (hexagonal and monoclinic) and morphology (granular, nanofiber and nanoplate). We studied the electrochemical and transistor properties of the oxides using, as the gating media, two different ion gels prepared from the same ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM]TFSI), and two different block copolymers. We tentatively propose that for sufficiently high values of the gate–source bias, the doping results from chemical and electrochemical contributions.

Background: Alzheimer’s disease (AD) is a neurodegenerative disease featured by memory loss, neuroinflammation and oxidative stress. Overproduction or insufficient clearance of Aβ leads to its pathological aggregation and deposition, which is considered the predominant neuropathological hallmark of AD. Therefore, reducing Aβ levels and inhibiting Aβ-induced neurotoxicity are feasible therapeutic strategies for AD treatment. Wolfberry has been traditionally used as a natural antioxidant and anti-aging product. However, whether wolfberry species has therapeutic potential on AD remains unknown. Method: The effects of fruitless wolfberry-sprout extract (FWE) on Aβ fibrillation and fibril disaggregation was measured by thioflavin T fluorescence and transmission electron microscope imaging; Aβ oligomer level was determined by dot-blot; Cell viability and apoptosis was assessed by MTT and TUNEL assay. The levels of Aβ40/42, oxidative stress biomarkers and inflammatory cytokines were detected by corresponding kits. 8-month-old male APP/PS1 mice and their age-matched WT littermates were treated with FWE or vehicle by oral administration (gavage) once a day for 4 weeks. Then the cognitive performance was determined using object recognition test and Y-maze test. The Aβ burden and gliosis was evaluated by immunostaining and immunoblotting, respectively. Results: FWE significantly inhibited Aβ fibrillation and disaggregated the formed Aβ fibrils, lowered Aβ oligomer level and Aβ-induced neuro-cytotoxicity, and attenuated oxidative stress in vitro. Oral administration of FWE remarkably improved cognitive function, reduced Aβ burden, decreased gliosis and inflammatory cytokines release, and ameliorated oxidative stress in the brains of APP/PS1 mice. Conclusion: These findings indicate that FWE is a promising natural agent for AD treatment.