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Ion doping strategy is a promising method to enhance the efficiency of Cu2ZnSn(S,Se)4 (CZTSSe) solar cells, however, most of the reported works focus on studying the single ion doping in CZTSSe absorber layers. Here, Li+&Ag+ and Li+&Cd2+ double-ion-doping strategy are applied to improve the microstructure and device performances. We found that the double-ion-doping strategy can obviously increase the grain size, reduce the thickness of fine-grain layers and enhance the device performances. Furthermore, the PCEs of Li+&Ag+ and Li+&Cd2+ doped CZTSSe solar cells are up to 8.87% and 8.39%, respectively. It shows an encouraging improvement of over 43.5% and 35.8% enhancement compared with the traditional method (6.18%), and significantly higher than single ion doping strategy (7.60%, 7.99% and 7.11% for Li+, Ag+, and Cd2+ doped CZTSSe solar cells). This work provides a new solution to improve the microstructure and device performances of CZTSSe solar cells.

The improvement of recrystallization texture and magnetic properties in grain-oriented electrical steel with trace Bi addition processed by strip casting process was studied in this study. Low casting temperature and sufficient liquid steel flow during strip casting process enabled relatively homogeneous distribution of Bi in the as-cast strip, which accelerated the precipitation during solidification and cooling process. As a result, relatively high density of duplex MnS + AlN, MnS and AlN was formed at grain boundaries and inside grain. Due to the synergistic effect of continuous precipitation and fragmentation of coarse precipitates during cold rolling, the number density of precipitates was increased and mean size was decreased along the processing route. High density of precipitates is attributed to severe inhomogeneous plastic deformation, which promoted the formation of high density in-grain shear bands during cold rolling and recrystallization Goss texture during annealing. Homogeneous microstructure with average grain size of ~ 11.6 μm, strong Goss texture with intensity of 2.5 multiples of random distribution, fine precipitates with number density of ~ 1.9 × 109 /cm2 and mean size of ~ 49 nm were formed after primary recrystallization annealing. Furthermore, grain-oriented electrical steel with Bi addition experienced complete secondary recrystallization of exact Goss grains during high-temperature annealing, which is attributed to beneficial optimization of Goss texture and strong inhibition effect, and superior magnetic induction B8 of 1.91 T was obtained. It is expected that this study paves a new way for fabrication of high-performance grain-oriented electrical steel.

Alkali-metal-ion doping is an efficient strategy to improve the device performance of thin film solar cells. Though doping with Li+ or Cs+ doping has been reported in Ag–Bi–I solar cells, the influence of doping with other alkali metal ions on Ag–Bi–I solar cells has not been systematically studied. In this work, we investigate the effects of five alkali metal ions (Li+, Na+, K+, Rb+, and Cs+) on the structure, morphology, and optical and electrical properties of Ag2BiI5 absorber layers, and also their influence on the device performance. All alkali-metal-doped Ag2BiI5 thin films show high crystallinity and have similar suitable band gaps. Hall effect measurements demonstrate that the alkali-metal-doped Ag2BiI5 films show an improved electrical performance compared with the pristine Ag2BiI5 thin film, which is beneficial to achieving high-efficiency solar cells. Unexpectedly, Cs+ doping can significantly increase the grain size of Ag2BiI5 thin films, leading to a porous absorber that reduces the device efficiency. The device performance of Li+-, Na+-, K+- and Rb+-doped Ag2BiI5 is significantly improved compared with that of pristine Ag2BiI5. It is found that the order of the power conversion efficiency promotion ability is K+ > Rb+ > Na+ > Li+ > Cs+ under the same experimental conditions. The present approach can be extended to other Bi-based solar cells to improve their device performance, which is critical for applications in absorbers with poor electrical performance or low crystallinity.

The scaling-up issue, mechanical instability, and possible packing capacity loss during pelletization remain as the major obstacles for the application of metal–organic frameworks (MOFs) in practic...

Hypothesis Droplet impact on cylindrical surfaces is a widespread phenomenon observed in both nature and industrial applications. The wettability and size of the cylinders, and the initial impact velocity, are expected to influence the impact dynamics, such as generating different droplet morphology, spreading/retracting processes, and contact time, which could finally determine the anti-icing property of power transmission lines. Experiments A particle-based mesh-free numerical approach, many-body dissipative particle dynamics, is employed to study the impact dynamics. The cylinders with three different sizes and three types of wettability are modelled, and different initial impact velocities are set. Findings The simulations show the two liquid films (or lamellae) formed after impact can coalesce at the bottom site of a hydrophilic cylinder while they keep separate on hydrophobic and superhydrophobic cylinders. The maximum spreading diameter in the axial direction increases with the increase of impact velocity and cylinder size. Besides, the distribution of droplet detachment mode shows a strong dependence on initial impact velocity and cylinder size. In bouncing mode, the contact time increases with the increase of impact velocity while in dripping/bouncing mode, it has an opposite trend. The splashing angle is also observed to be dependent on the cylinder size.

Stimulated by novel properties in topological insulators, experimentally realizing quantum phases of matter and employing control over their properties have become a central goal in condensed matte...

This article reports microstructural characterization of as-cast and as-extruded Zn-Fe alloys and their mechanical and corrosion properties. Specifically, 1 wt.%, 2 wt.% and 3 wt.% Fe was added into the Zn matrix to form respective Zn-Fe alloys using casting and indirect hot extrusion processes. As the Fe content increased within the range of 1–3 wt.%, the mechanical properties of as-cast and as-extruded Zn-Fe alloys improved. The as-extruded Zn-Fe alloys showed superior mechanical properties of hardness, ultimate tensile strength (UTS) and elongation to failure (EL) to the as-cast Zn-Fe alloys of the same composition. Specifically, the UTS for as-extruded Zn-Fe alloys was 138–170 MPa, whereas the UTS for as-cast Zn-Fe alloys was 89–125 MPa. The corrosion properties of the as-extruded Zn-Fe alloys were investigated using the electrochemical and immersion methods. The corrosion rate of the as-extruded Zn-Fe alloys ranged from 0.015 mm/year to 0.210 mm/year.

The crystal quality of Cu2ZnSn(S,Se)4 (CZTSSe) thin film is crucially important to the high-performance CZTSSe solar cell. After the selenization, a bi-layer CZTSSe thin film consisting of a large-...

Although many studies on luminescent metal–organic frameworks (MOFs) have been reported for chemical sensing applications, it has yet to be realized in MOFs the precise linearity control over photo...

State-of-the-art chemical sensors based on covalent organic frameworks (COFs) are restricted to the transduction mechanism relying on luminescence quenching and/or enhancement. Herein, we present an alternative methodology via a combination of in situ-grown COF films with interdigitated electrodes utilized for capacitive benzene detection. The resultant COF-based sensors exhibit highly sensitive and selective detection at room temperature toward benzene vapor over carbon dioxide, methane, and propane. Their benzene detection limit can reach 340 ppb, slightly inferior to those of the metal oxide semiconductor-based sensors, but with reduced power consumption and increased selectivity. Such a sensing behavior can be attributed to the large dielectric constant of the benzene molecule, distinctive adsorptivity of the chosen COF toward benzene, and structural distortion induced by the custom-made interaction pair, which is corroborated by sorption measurements and density functional theory (DFT) calculations. This study provides new perspectives for fabricating COF-based sensors with specific functionality targeted for selective gas detection.

In this article, a new technique to design a low-profile planar vortex beam generator is proposed based on microwave frequency selective surface (FSS), which is capable of generating orbital angular momentum (OAM) mode under circularly polarized incidence. Such OAM generator is composed of transmissive units distributed over a planar surface. Each unit cell, behaving as a spatial phase shifter, is composed of a stack of patches and grids separated by thin dielectric substrates. In order to reduce the thickness of the device, a rectangular patch is embedded in the middle layer to introduce an additional resonance. Compared to other resonant unit cells, this structure presents nearly perfect efficiency to convert circularly polarized incident wave to its cross-polarized component. A simple equivalent circuit model, composed of transmission lines coupled together with shunt capacitors and inductors, is presented to analyze this structure. The prototype of the proposed planar OAM generator operating in $x$ -band is designed, fabricated, and experimentally characterized. Good agreement is achieved between full-wave simulations and measurements. It is demonstrated that the generator can achieve an efficiency of 85% at 10.7 GHz with an overall thickness of $0.067\lambda _{0}$ .

This work reports a template-free wet chemical synthesis method for economical production of zinc oxide (ZnO) microrods by using an inexpensive polypropylene beaker as a reactor under atmospheric pressure. The morphology and crystal structure of the as-prepared ZnO microrods were investigated by scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and Raman scattering. Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), Ultraviolet–visible (UV/Vis) spectroscopy and methylene blue photocatalytic degradation test were also conducted to study their physical and chemical properties. The results show that the as-prepared ZnO microrods have a hexagonal crystal structure. Under the optimal synthesis condition, they have a diameter of 0.8–2.6 μm and a length of 10–40 μm. Compared with commercial ZnO powders, the as-prepared ZnO microrods have a higher whiteness. Meanwhile, the as-prepared ZnO microrods have very low photocatalytic activity, indicating that they have good photostability and are unlikely to cause the photodegradation of polymers such as binders. As a result, they will be an excellent and economical white pigment with great potential in coating applications.

Fabricating flexible, stable and highly reproducible surface-enhanced Raman scattering (SERS) active substrates is very important in furthering the development of practical SERS sensors. Nevertheless, the fabrication of such SERS substrates is rather challenging in processing conditions for both noble metal and semiconductor substrates. In this study, highly sensitive SERS detection is achieved by fabricating novel textile-based SERS substrates with a structure of graphite/titanium/cotton which are prepared by sputtering cotton fabric with titanium and graphite for different lengths of time at room temperature. The resultant samples show excellent SERS with an enhancement factor of 1.6 × 104, limit of detection of 4 × 10−7 as well as outstanding flexibility. The optimal SERS active substrate in this study also shows promising application for conformal rapid detection in the field of food safety testing.

The density, viscosity, and refractive index data of binary mixtures for the main components of biodiesel (ethyl caprylate, ethyl caprate, and ethyl myristate) with ethylcyclohexane in the whole ra...

Articular cartilage has very poor intrinsic healing ability and its repair remains a significant clinical challenge. To promote neocartilage regeneration, we fabricated two collagen (Col) scaffolds functionalized with a porcine decellularized extracellular matrix (dECM) in the forms of particle and solution named pE-Col and sE-Col, respectively. Their differences were systematically compared, including the biochemical compositions, scaffold properties, cell-material interactions, and in situ cartilage regeneration. While it is demonstrated that both forms of dECM could enhance the cell recruitment, proliferation, and chondrogenesis of bone marrow stem cells (BMSCs) in vitro, better performance was seen in the sE-Col group, which could quickly provide a more favorable chondrogenic microenvironment for endogenous BMSCs. The superiority of sE-Col was also proved by our in vivo study, which showed that the sE-Col scaffold achieved better structural hyaline-like neocartilage formation and subchondral bone repair compared to the pE-Col scaffold, according to the gross morphology, biological assessment, and micro-CT imaging analysis. Together, this study suggests that the sE-Col scaffold holds great potential in developing the one-step microfracture-based strategy for cartilage repair and also reminds us that despite dECM being a promising biomaterial in tissue engineering, the optimization of the proper processing methodology would be a crucial consideration in the future design of dECM-based scaffolds in articular cartilage regeneration.

Droplets moving on surfaces are affected by the heterogeneity of the substrates. In the present study, the effects of partial heterogeneity of the substrates on the dynamic contact angles are numerically investigated by using a two-dimensional many-body dissipative particle dynamics (MDPD) model. The results show that for a droplet moving over a chemically heterogeneous island, the effects of the heterogeneity on the advancing and receding contact angles are largely different, although both the advancing and receding contact angles increase firstly when the front contact point reaches the heterogeneous island. In the meantime, the front contact point gets pinned and de-pinned alternately with the shape of the droplet deforming periodically while it is not so apparent for the rear contact point. Both the advancing and receding contact angles experience drastic fluctuation when the front contact point passes the island and it is different for the tail of the droplet passing the island. Also, the kinetic energy of the droplet decreases rapidly. In addition, the energy dissipation increases with the increasing number of stripes in the island region. The results illustrate that the advancing contact angle has higher sensitivity to the heterogeneity of the substrate than the receding one. Our findings can bring an insight on the mechanism of micro-droplets moving on heterogeneous substrates.

Droplets sliding on surfaces always exhibit an advancing and a receding contact angle. When exerting different driving forces on the droplet to force it to slide at different velocities, the droplet would alter its shape to adapt to the new motion. Hence, different advancing/receding contact angles are likely to be observed, leading to the multiple contact angle hysteresis on a given surface. To verify this hypothesis, many-body dissipative particle dynamics is employed to perform the sliding simulation on both chemically homogeneous and heterogeneous surfaces. By ensuring the droplet sliding in uniform motions under different driving forces, the advancing/receding contact angles are recorded for analysis. Simulation results show that, for homogeneous surfaces, a larger driving force can result in both larger advancing contact angle and smaller receding contact angle, while for heterogeneous surfaces, increasing the driving force only results in smaller receding contact angles. For both cases, multiple contact angle hysteresis can be observed. These observations are contrary to the currently prevailing opinion, which believes that the contact angle hysteresis should be unique on given surfaces. Our findings would advance the understanding of wetting phenomena and possibly inspire new guidance for the design of functional interfaces.

In order to investigate the effects of solid solution atoms, precipitated particles and cold deformation on the microstructures and properties of Al–Sc–Zr alloys, the Al–Sc–Zr alloys prepared by continuous rheo-extrusion were treated by thermomechanical treatment, analyzed for conductivity and mechanical properties by tensile and microhardness testing, and characterized using optical microscope, TEM and STEM. A mathematical model was established to quantitatively characterize the contribution of solid solution atoms, precipitates and cold deformation to the conductivity of the alloy. The results show that the strength of Al alloy can be significantly improved by solid solution, aging and cold deformation, and the quantitative impacts of solution atoms, precipitates and cold deformation on the conductivity of Al alloy are 10.5% (IACS), 2.3% (IACS) and 0.5% (IACS), respectively. Aging and cold deformation treatments are the keys to obtain high-strength and high-conductivity aluminum alloy wires.

In virtual vector control schemes for single-phase current-regulated voltage source inverters, many methods are proposed to generate a virtual orthogonal feedback current from the real feedback current. However, the generation stage causes mismatch between feedback and command currents, which may deteriorate dynamic current-tracking capability and power quality. A precise scalar model is developed to analyze the phenomenon. Based on this model, the mismatch is presented as a current disturbance signal introduced into the control loop. The mathematical analysis establishes that the current disturbance cannot be eliminated by any orthogonal signal generation (OSG) method. To solve the problem, a current precompensator is mooted. In this paper, the effect of the current precompensator is studied in detail. Furthermore, a voltage precompensator is proposed, which better suits OSG methods than the current precompensator. Experimental results of both the current and voltage precompensator are compared with the conventional solution to substantiate enhanced dynamic performance.

Membrane technology has aroused great attention for gas separations due to its high energy efficiency, small capital investment, easy and continuous operation. Mixed matrix membranes (MMMs) constructed from a continuous polymer phase and a dispersed filler phase offer new opportunities to achieve a breakthrough in fabricating high-performance membranes. Metal–organic frameworks (MOFs) have been regarded as potential fillers to boost the MMM separation performance. However, MOFs occasionally exhibit limited compatibility with the polymer matrixes owing to their partially inorganic structure and tendency of agglomeration in the membranes. Here, an interfacial design strategy is demonstrated by coating size-selective MOF cores with covalent organic framework (COF) layers to construct MOF@COF hybrids as fillers in MMMs for enhanced polymer-filler compatibility. The pure organic COF layers exhibit high affinity to the polymer matrix, thereby preventing the formation of nonselective interfacial voids and alleviating filler agglomeration. With the incorporation of only 5 wt% of MOF@COF fillers, the resultant MMM exhibits 48% and 79% enhancements in CO2 permeability and CO2/CH4 selectivity, respectively, with better operational stability compared to that of the pure polymeric membrane. These results reveal a novel filler design strategy for the tailored synthesis of high-performance MMMs for natural gas and biogas purification.

Engineering metal–organic frameworks (MOFs) for adsorptive ethylene/ethane separation has shown bright prospects for replacing the energy-intensive cryogenic distillation process. Herein, we demons...

Reverse micellar dyeing of cotton fabrics with PEG-based non-ionic surfactant in heptane non-aqueous medium with the use of reactive dyes with different reactive groups was investigated. Single jersey knitted fabrics were used in this study. The experimental results reveal that samples dyed by both one-bath and two-bath heptane reverse micellar methods can achieve higher colour yield than the conventional water-based dyeing method. Among different reactive dyes, samples dyed with hetero-bifunctional vinylsulfone based reactive dyes could achieved higher colour yield (K/S) than the homo-bifunctional and monofunctional reactive dyes in non-aqueous dyeing medium. Moreover, the ranges of L*, a* and b* value for hetero-bifunctional vinylsulfone based reactive dyes were narrower than homo-bifunctional and monofunctional reactive dyes. In term of levelness, monofunctional reactive dyes generally resulted a better levelness than homo-bifunctional and hetero-bifunctional reactive dyes. Although one-bath heptane method yields high K/Ssum values, the problem of unlevelness should be considered while the use of two-bath heptane reverse micellar method can strike a balance between levelness and colour yield.

Advanced porous materials (APMs) constructed from structure-encoded building blocks present an unprecedented degree for molecular design, and have demonstrated class-leading performance in numerous applications. However, the development of economically viable and sustainable synthetic means of production is a critical prerequisite to translate APMs to real-world applications. In this Perspective, we first consider the diverse synthetic routes to APMs—metal/covalent organic frameworks (MOFs/COFs), porous organic polymers (POPs) and porous molecular solids—and highlight the challenges for scalable and sustainable synthesis. Subsequently, we illustrate concepts to guide the sustainable synthesis of APMs with recent examples in the literature. Lastly, we present our outlook for the translation of molecular design to scalable APM production.

Mixed matrix membranes (MMMs) have long been considered as promising membrane types for industrial energy-intensive gas separation processes. Current MMMs are still facing grand challenges of poor filler dispersion and poor polymer-filler interfacial compatibility. The present study demonstrates that these challenges can be addressed by fabricating MMMs containing three-dimensional (3D) covalent organic framework (COF) fillers with ultrasmall size-selective pores. Two different polymer matrixes, including glassy 6FDA-DAM and rubbery Pebax, are explored to validate the effectiveness of 3D COF fillers in improving the membrane separation performance. The pure organic nature of COFs facilitates their high affinity with pure organic polymer matrixes, leading to good interfacial compatibility in the resultant MMMs. These porous COF-300 fillers can increase the membrane fractional free volume that enhances the membrane gas permeability. Besides, the ultrasmall pores of COF-300 fillers and the rigidified polymer chains at the filler surface can enhance the size discriminative processes, resulting in increased membrane gas pair selectivity. Moreover, the separation performance of COF-300 can be further improved by functionalizing it with polyethylenimine (PEI), enabling the design of advanced membranes suitable for industrial applications.

Four chiral AIE-active luminogens (AIEgens) containing tetraphenylethene (TPE) and one or two chiral glutamic moieties connected by thiourea were designed and synthesized. All AIEgens showed tunable aggregation-induced circularly polarized luminescence (AICPL) by adjusting the mono-/di-substituents of molecules or nanostructures of self-assemblies. The enantiotopic mono-substituted compounds (TPE-Glu) exhibited mirror-imaged AICPL signals with the maximal |glum| value of up to 0.02. Interestingly, the di-substituted cis- and trans-isomers showed reverse AICPL signals compared with those of mono-substituted ones. cis- and trans-isomers (TPE-DGlu) showed similar AICPL properties, whose signs of AICPL signals reversed while the water fraction (fw) was more than 80%. The SEM images of their self-assemblies indicated that the AICPL properties should have an intrinsic relation with their molecular structures or self-assembled nanostructures.

In this work, spindle-shaped cells derived from bone marrow were separated from the regenerated tissue of an osteochondral defect in a SD rat model. These cells were defined as MSC-like cells because they revealed similar features with MSCs, as demonstrated by the cell morphological observation, H&E staining of the regenerated tissue, typical MSC surface markers, and the differentiation potential assays in osteogenesis, adipogenesis, and chondrogenesis. Bioinert agarose and bioactive collagen I hydrogels were filled in the osteochondral defects to investigate the effects of different biomaterials on the MSC-like cell migration, differentiation, and osteochondral regeneration. After one month's surgery, the defect site was evaluated by histologic staining, IHC staining and micro-CT. These results indicated that the bioinert agarose significantly inhibited cell migration and tissue regeneration, while the bioactive collagen I hydrogel was found to have a therapeutic effect. It would be tempting to speculate that the specifically designed scaffolds that facilitated cell migration were more propitious to osteochondral defect healing. The migration of the MSC-like cells into the osteochondral defect had produced promising outcomes and showed therapeutic potency. In the future, additional work will focus on elucidating the sophisticated mechanisms underlying the origin of the MSC-like cells, function and consequences of cell migration to understand the treatment of osteochondral defects.

Mixed matrix membranes (MMMs) have gained great attention for the efficient CO2 removal from raw nature gas or biogas (CO2/CH4 separation) and flue gas (CO2/N2 separation). Nevertheless, the development of high-performance MMMs for industrial applications is largely limited by the lack of suitable porous fillers. Herein, a novel ionic covalent organic polymer (ICOP-1) consisting of gas selective pores and hollow cavities is facilely fabricated using a metal triflate catalyzed condensation reaction. Considering its unique structural properties, ICOP-1 is explored as a novel filler to enhance the gas separation properties of polysulfone (PSf) membranes. Defect-free MMMs are successfully prepared owing to the high polymer–filler affinity originating from the organic nature of these two phases. Besides, the large cavities and size-selective pores of ICOP-1 lead to a simultaneous increase in membrane CO2 permeability and CO2/CH4, CO2/N2 selectivities. With the addition of only 0.5 wt % of ICOP-1 fillers, the a...

Covalent organic frameworks (COFs) have emerged as promising crystalline porous materials with well-defined structures, high porosity, tunable topology, and functionalities suitable for various applications. However, studies of few-layered ultrathin two-dimensional (2D) COF nanosheets, which may lead to unprecedented properties and applications, are still limited. Herein, we report the targeted synthesis of three azine-linked and imine-linked 2D COFs named NUS 30–32 using monomers containing aggregation-induced emission (AIE) rotor-active tetraphenylethylene (TPE) moieties, affording micro- and meso-dual pores in NUS-30 and NUS-32 and triple pores in NUS-31. For the first time, we demonstrate that these isostructural bulk COF powders can be exfoliated into ultrathin 2D nanosheets (2–4 nm thickness) by a temperature-swing gas exfoliation approach. Compared with TPE monomers and COF model compounds, the AIE characteristic of NUS 30–32 nanosheets is distinctly suppressed because of the covalent restriction o...

Use of reactive dyes of red, blue and yellow colours for exhaustion dyeing of cotton conventional water-based dyeing method and PEG-based solvent-assisted reverse micelle dyeing method was investigated. Calibration curves of both dyeing approaches were established. The calibration results show that red dye can achieve higher absorbance value than yellow and blue dyes and the R-square of the curves can reach a value above 0.99 which indicates the curves are linear in structure and suitable for subsequent measurement. The values of substantivity factor (S), exhaustion factor (E), rate of fixation (R) and fixation factor (F) (SERF) are measured in percentage. The results reveal that using reverse micelle method can achieve higher dye absorption in both exhaustion and fixation processes, resulting in higher final exhaustion of dye in fibre than with the conventional water-based method. Therefore, the reverse micellar dyed samples generally can obtain higher dye absorption, lower reflectance percentage and darker shade in appearance than conventional water-based dyeing.

Cap-like α-Fe2O3 films are fabricated and deposited onto quartz fabric by using radio frequency magnetron sputtering and annealing. The treated fabric sample in this study shows highly sensitive surface-enhanced Raman scattering (SERS) and excellent flexibility, reproducibility and stability. In addition, the sample can be recovered after a washing process with an organic solvent and repeatedly used. The sensitive SERS performance is attributed to chemical enhancement through a charge transfer process. Moreover, the SERS performance is also found to be dependent on the light coupling effect. When the light absorbance rate of the α-Fe2O3 films increases at a wavelength near that of laser light, the film shows excellent sensitivity due to light coupling effect.

Differentiation of xylene isomers remains as one of the most important challenges in the chemical industry, mainly due to the similar molecular sizes and boiling points of the three xylene isomers. Fluorescence-based chemical sensors have attracted wide attention due to their high sensitivity and versatile applications. Here, we report a novel fluorescent metal-organic framework named NUS-40, which is able to selectively detect and discriminate o-xylene from other xylene isomers. Suspension of NUS-40 in o-xylene produces a distinct red shift in the fluorescence emission compared to that in either m-xylene or p-xylene. Moreover, the extent of peak shift is dependent on the concentration of o-xylene in xylene isomer mixtures, and the observed linear correlation between fluorescence intensity and o-xylene concentration is beneficial for quantitative detection. The possible mechanism of such responsive fluorescence behavior was investigated by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, and vapor sorption experiments. In addition, facile metalation of the porphyrin centers with metal ions provides an additional route to fine-tune the sensing properties.

Phase and porosity control in titanium dioxide (TiO2) is essential for the optimization of its photocatalytic activity. However, concurrent control over these two parameters remains challenging. Here, a novel metal-organic framework templating strategy is demonstrated for the preparation of highly microporous anatase TiO2. In situ encapsulation of Ti precursor in ZIF-8 cavities, followed by hydrolysis and etching, produces anatase TiO2 with a high Brunauer-Emmett-Teller surface area of 335 m2·g-1 and a micropore surface area ratio of 48%. Photocatalytic hydrogen generation catalyzed by the porous TiO2 can reach a rate of 2459 μmol·g-1·h-1. The measured photocatalytic activity is found to be positively correlated to the surface area, highlighting the importance of porosity control in heterogeneous photocatalysts.

Understanding how we perceive differences in material compliance, or 'softness,' is a central topic in the field of haptics. The intrinsic elasticity of an object is the primary factor thought to influence our perceptual estimates. Therefore, most studies test and report the elasticity of their stimuli, typically as stiffness or modulus. However, many reported estimates are of very high magnitude for silicone-elastomers, which may be due to artifacts in characterization technique. This makes it very difficult to compare the perceptual results between the studies. The work herein defines a standardized and easy-to-implement way to characterize test stimuli. The procedure involves the unconstrained, uniaxial compression of a plate into cylindrical substrates 10 mm tall by 10 mm diameter. The resultant force-displacement data are straightforwardly converted into stress-strain data, from which a modulus is readily derived. This procedure was used to re-characterize stimuli from prior studies. The revised results from the validated method herein are 200-1,100 percent lower than modulus values either reported and/or approximated from stiffness. This is practically significant when differences of 10-15 percent are perceptually discriminable. The re-characterized estimates are useful in comparing prior studies and designing new studies. Furthermore, this characterization methodology may help more readily bridge studies on perception with those designing technology.

Introducing nonvolatile liquid acids into porous solids is a promising solution to construct anhydrous proton-conducting electrolytes, but due to weak coordination or covalent bonds building these solids, they often suffer from structural instability in acidic environments. Herein, we report a series of steady conjugated microporous polymers (CMPs) linked by robust alkynyl bonds and functionalized with perfluoroalkyl groups and incorporate them with phosphoric acid. The resulting composite electrolyte exhibits high anhydrous proton conductivity at 30-120 °C (up to 4.39 × 10-3 S cm-1), and the activation energy is less than 0.4 eV. The excellent proton conductivity is attributed to the hydrophobic pores that provide nanospace for continuous proton transport, and the hydrogen bonding between phosphoric acid and perfluoroalkyl chains of CMPs promotes short-distance proton hopping from one side to the other.

Although platelet-rich plasma (PRP) plays a significant role in the orthopedic clinical application, it still faces two major problems, namely, uncontrollable factors release, frequent preparation and extraction processes as well as the inconvenient form of usage. To overcome these shortcomings, freeze-dried PRP (LyPRP) was encapsulated into bioactive Col I hydrogel to induce osteogenic differentiation of rabbit bone marrow mesenchymal stem cells (rBMSCs). And PRP/Col І composite hydrogel was prepared as a control. Compared with Col І hydrogel, the introduction of platelets significantly improved the mechanical properties of hydrogels. Meanwhile, platelets were evenly distributed in the composite hydrogels network. The sustainable release of related factors in the composite hydrogels could last for more than 14 days to maintain its long-term biological activity. Further cell experiments confirmed that PRP and LyPRP could effectively alleviate the contraction of collagen hydrogel in vitro, and promote the adhesion, proliferation and osteogenesis differentiation of rBMSCs. The results of osteogenic gene expression indicated that the 10% LyPRP/Col І composite hydrogel could facilitate the early expression of BMP-2 and late osteogenic associated protein formation with higher expression of alkaline phosphatase and Osteocalcin (OCN). These results might provide new insights for the clinical application of 10% LyPRP/Col І composite hydrogel as practical bone repair injection.

A novel metagrating is proposed to achieve single order diffraction. The proposed unit has electric and magnetic hybrid response. The unit is composed of asymmetrical patch. By introducing magnetic response, the element will break the symmetry of diffraction. One of the first order diffraction is canceled and the energy is totally reflected into the other order at 10GHz. Besides, the diffraction efficiency is higher than 80% from 9.4GHz to 11.1GHz. The simulated far field pattern shows good agreement with prediction. The proposed design provide a highly efficient method to suppress 0 and +1 order diffraction and simplify the difficulty of design, paving the way for further applications of beam steering.

Significant control and modulation delay presents in the current regulation of high-power voltage source converters. The proportional-resonant controller (PR) with equalized phase correction (EPC), commonly used in the active power filter, can be referred here to suppress the negative sequence current better than the PI controller, and increase the phase margin with EPC. After introducing the current feedback (CF), proved to increase the tracking performance similarly to that in the dq-axis, the double-sided frequency domain becomes asymmetric, making EPC less effective. In this paper, the PR controller with differentiated phase correction (DPC) is proposed, with two independent phase correction angles and gains at the positive and negative poles. Analyzed with double-sided bode diagram, the stability margins are improved with the two extra freedom degrees. Moreover, the function related to the conjugate symmetry about the fundamental frequency is used to quantitively describe the response of such asymmetric system. Finally, simulation and experiment are implemented to verify the improved dynamic performance of the proposed one versus the compared schemes.

A CNN based algorithm is proposed for the estimation of nonlinear phase shift. Simulations show that the mean relative errors of it can achieve 2%, and it is insensitive to the changing of baud-rate.

The invention discloses a multi-attribute approximate nearest neighbor searching method based on a navigable small world graph. The method comprises the following steps that: Step 1, an MA-NSW index generation method, which comprises the steps of constructing and traversing a node set P with multiple attributes, inserting each node into a coverage layer of a corresponding attribute of an MA-NSW index, and storing the MA-NSW index as a binary file; and Step 2, an MA-NSW multi-attribute approximate nearest neighbor search method, which comprises the steps of inputting a target node with multipleattributes, finding a corresponding coverage layer according to the multiple attributes, and searching k nearest neighbor nodes of the target node in the coverage layer by using a greedy algorithm. According to the method, a plurality of coverage layers are used for recording a node set of each attribute combination and respectively forming a navigable small world graph (NSW) structure, and the node attribute combinations in the same coverage layer are the same so as to support multi-attribute approximate nearest neighbor search.

Ethylene glycol (EG)-based hybrid nanofluids containing graphene oxide–silver nanosheets (GO–Ag) were simply prepared without using any surfactant. The graphene oxide–silver composites were characterized using X-ray diffraction analysis, transmission electron microscope, infrared and UV–visible spectroscopy. The stability of GO–Ag nanofluids was estimated by UV–visible spectroscopy. The GO–Ag/EG hybrid nanofluids has good stability without significant sedimentation for 60 days. A few thermophysical properties of GO–Ag/EG nanofluids with 0.1, 0.2 and 0.3 wt% nanosheets were analysed experimentally at different temperatures ranging from 20 to 50°C.

Summary Decades of artificial selection have significantly improved performance and efficiency of animal production systems. However, little is known about the microevolution of genomes due to intensive breeding. Using whole-genome sequencing, we document dynamic changes of chicken genomes under divergent selection on adiposity over 19 generations. Directional selection reduced within-line but increased between-line genomic differences. We observed that artificial selection tended to result in recruitment of preexisting variations of genes related to adipose tissue growth. In addition, novel mutations contributed to divergence of phenotypes under selection but contributed significantly less than preexisting genomic variants. Integration of 15 generations genome sequencing, genome-wide association study, and multi-omics data further identified that genes involved in signaling pathways important to adipogenesis, such as autophagy and lysosome (URI1, MBL2), neural system (CHAT), and endocrine (PCSK1) pathways, were under strong selection. Our study provides insights into the microevolutionary dynamics of domestic animal genomes under artificial selection., Graphical Abstract, Highlights • Directional selection reduces within-line but increases between-line genomic difference • Artificial selection tends to recruit preexisting variations of genes for fatness • Novel mutations contribute to the divergence of fatness under artificial selection • Genes involved in signaling pathways important to adipogenesis are under selection, Biological Sciences; Evolutionary Biology; Genetics; Genomics

Current evaluation methods for soccer player performance either relies on rating from soccer experts or structured statistics of the match, such as shots and tackles. The former needs a lot of manpower and the evaluation is inevitably subjective. The latter can only record the quantity of a player's match events, but cannot reflect the quality (e.g., a wonderful shot or a terrible shot is regarded as a shot). To solve the above problems, an improved evaluation method for soccer player performance using affective computing is proposed. On the basis of statistics, our method also takes advantage of the text information of post-match reports, and employ the affective computing technology to quantify the quality of events. In this way, both the quantity and quality of events are considered. All the players in the Chinese Super League 2019 season are selected as evaluation objects, and the results show that the improved method can evaluate player performance more effectively and reasonably.

The complex systems with edge computing require a huge amount of multifeature data to extract appropriate insights for their decision making, so it is important to find a feasible feature selection method to improve the computational efficiency and save the resource consumption. In this paper, a quantum-based feature selection algorithm for the multiclassification problem, namely, QReliefF, is proposed, which can effectively reduce the complexity of algorithm and improve its computational efficiency. First, all features of each sample are encoded into a quantum state by performing operations CMP and Ry, and then the amplitude estimation is applied to calculate the similarity between any two quantum states (i.e., two samples). According to the similarities, the Grover–Long method is utilized to find the nearest k neighbor samples, and then the weight vector is updated. After a certain number of iterations through the above process, the desired features can be selected with regards to the final weight vector and the threshold τ. Compared with the classical ReliefF algorithm, our algorithm reduces the complexity of similarity calculation from O(MN) to O(M), the complexity of finding the nearest neighbor from O(M) to OM, and resource consumption from O(MN) to O(MlogN). Meanwhile, compared with the quantum Relief algorithm, our algorithm is superior in finding the nearest neighbor, reducing the complexity from O(M) to OM. Finally, in order to verify the feasibility of our algorithm, a simulation experiment based on Rigetti with a simple example is performed.

Friction is a nonlinear effect that occurs in all mechanical systems which may cause limit cycles, tracking errors, and other undesirable effects. Traditional static friction models cannot characterize all the friction situations. In recent years, neural network (NN) technique has been widely used to approximate the nonlinear function. In this paper, a new method which combines radical basis function neural network (BRFNN) with beetle antennae search (BAS) algorithm for modeling friction in a robotic joint is proposed. Velocity, load, and temperature are considered as the three factors that influence the static friction. It is shown that the proposed BAS-RBFNN possesses better performance in terms of faster convergence rate and higher accuracy.

The positioning accuracy of a robot is of great significance in advanced robotic manufacturing systems. This paper proposes a novel calibration method for improving robot positioning accuracy. First of all, geometric parameters are identified on the basis of the product of exponentials (POE) formula. The errors of the reduction ratio and the coupling ratio are identified at the same time. Then, joint stiffness identification is carried out by adding a load to the end-effector. Finally, residual errors caused by nongeometric parameters are compensated by a multilayer perceptron neural network (MLPNN) based on beetle swarm optimization algorithm. The calibration is implemented on a SIASUN SR210D robot manipulator. Results show that the proposed method possesses better performance in terms of faster convergence and higher precision.

In our ability to discriminate compliant, or ‘soft,’ objects, we rely upon information acquired from interactions at the finger pad. We have yet to resolve the most pertinent perceptual cues. However, doing so is vital for building effective, dynamic displays. By introducing psychophysical illusions through spheres of various size and elasticity, we investigate the utility of contact area cues, thought to be key in encoding compliance. For both active and passive touch, we determine finger pad-to-stimulus contact areas, using an ink-based procedure, as well as discrimination thresholds. The findings indicate that in passive touch, participants cannot discriminate certain small compliant versus large stiff spheres, which generate similar contact areas. In active touch, however, participants easily discriminate these spheres, though contact areas remain similar. Supplementary cues based on stimulus rate and/or proprioception seem vital. One cue that does differ for illusion cases is finger displacement given a volitionally applied force.

Postcombustion CO2 capture from wet flue gas is a daunting challenge that metal–organic-framework-based (MOF-based) adsorbents need to address, because the moisture in the gas stream may not only hydrolyze the coordination bonds of MOFs but also be competitively adsorbed in MOFs leading to compromised CO2 capture performance. In this study, two isostructural water-stable MOFs decorated with alkyl groups, namely, UiO-66(Zr)-(OAc)2 and UiO-66(Zr)-(OPr)2, are synthesized from UiO-66(Zr)-(OH)2 via a facile postsynthetic esterification strategy and evaluated for their water affinity and CO2 capture performance. The increased water contact angle and reduced water vapor capacity at 60% relative humidity indicate the positive role of the propionyl group of UiO-66(Zr)-(OPr)2 in reducing material hydrophilicity. When the adsorbent beds are not fully saturated with water, breakthrough experiments using simulated wet flue gas reveal that UiO-66(Zr)-(OPr)2 possesses a CO2/N2 adsorption selectivity of 76.6, which is 22...

Both humans and objects can emit infrared (IR) wavelengths which generate thermal emissions that can be detected with an IR camera. Therefore, highly IR reflective materials have been the subject of interest recently, for example, in achieving IR stealth. In this work, IR reflective coatings on polyester fabric in the form of a titanium dioxide/copper/titanium dioxide (TiO2/Cu/TiO2; TCT) sandwich-like structure are fabricated by using magnetron sputtering. The coated fabric samples are then examined by using an energy dispersive X-ray detector, a scanning electron microscope and an X-ray diffractometer. The reflection of IR wavelengths which range from 8 to 14 µm of the TCT coated fabric is evaluated. The bending stiffness, and mechanical and adhesion strengths of the coated fabric samples are also investigated. The results show that the TCT sandwich-like structure on the polyester fabric sputtered for 30 min with Cu which results in a Cu film of 200 nm in thickness is observed to have the maximum reflection of IR wavelengths. The color of the TCT coated polyester fabric samples sputtered for 5, 10, 20, and 30 min with Cu is green, yellow, brown and purple, respectively. The TCT coated fabric therefore has potential applications as IR protection textiles for military purposes.

In this paper, the microstructure and properties of as-cast Cu-Y-Zr alloys with different Zr content were studied in order to investigate whether the precipitates in copper alloys would interact with each other by adding Y and Zr simultaneously. As-cast Cu-0.5Y-xZr (wt.%, x = 0.05 and 0.1, nominal composition) alloys were prepared by vacuum melting in this study. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and transmission electron microscopy (TEM) were used to observe the microstructure of the alloys. The mechanical properties of the alloys were tested by universal material testing machine at room temperature. The effects of Zr content on the microstructure and mechanical properties of the alloys were explored. As shown by the research results, in the as-cast Cu-0.5Y-xZr (wt.%) alloys, the precipitated phase was the Cu5Y/Cu5Zr phase and ranged from 10 nm to 70 nm in size, when the Zr content increased from 0.05 wt.% to 0.1 wt.%, both the tensile strength and elongation rate of the alloys increased, when the Zr content was 0.1 wt.%, the tensile strength was 225 MPa and the elongation rate was 22.5%.