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In some thermally driven two-phase natural circulation systems, bubble pumps serve as the key driving powers for the cycles. Recently a type of distribute heating bubble pump generator (BPG) is gradually receiving attention due to its compact structure and great potentials to utilize solar energy and low-grade waste heat recovery. The BPG provides a variety of promising features (e.g., passive heat transfer, enhanced reliability), which can benefit the advancing of heat transfer technology. For the primary study, we performed an experiment in a distributed heating BPG. Through utilizing multiple lift tubes and partial visualization configurations, it provides accesses to observe the flow pattern transition and monitor the flow instability, and thus to explore some of the underlying mechanisms affecting BPG performance. Results showed that heat input and immersion height were crucial parameters to enable the operation of distribute heating BPG. With low heat input or high inlet water subcooling level, the flow within the pump was unstable with intermittent flow interruptions. As the heat input increased, the fluid flow became more stable, the vapor generation increased linearly, while the lifted liquid flow rate initially increased then decreased. Correspondingly, the flow pattern at the outlet section of lift tubes gradually changed from slug flow to churn flow, and then to annular flow. The higher of the immersion was, the higher heat input was needed for the flow pattern transition. It was in the churn flow regime at the outlet of lift tubes for the BPG to lift a maximum liquid. At lower immersion level, liquid reflux in the lift tubes was obvious and affected the flow stability as well as the lifting performance. At higher immersion level, the fluid flow was more stable and faster, which lifted more liquid while generated less vapor depending on the inlet subcooling. In general, the BPG showed better performance (both the lifted liquid and vapor generation increased) at smaller inlet subcooling level or lower system pressure. This study highlights the flow pattern evolution and flow stability, which is helpful to the reliable design and effective operation of the distributed heating BPG.

Wrinkles are special surface corrugations in two-dimensional materials, which can be used to tune their electronic, optical, and chemical properties. There have been many studies focusing on the wr...

Perovskite semiconductor nanocrystals have emerged as a promising family of materials for optoelectronic applications including light-emitting diodes, lasers, light-to-electricity convertors and quantum light emitters. The performances of these devices are fundamentally dependent on different aspects of the excited-state dynamics in nanocrystals. Herein, we summarize the recent progress on the photoinduced carrier dynamics studied by a variety of time-resolved spectroscopic methods in perovskite nanocrystals. We review the dynamics of carrier generation, recombination and transport under different excitation densities and photon energies to show the pathways that underpin the photophysics for light-emitting diodes and solar cells. Then, we highlight the up-to-date spin dynamics and coherent exciton dynamics being manifested with the exciton fine levels in perovskite semiconductor nanocrystals which are essential for potential applications in quantum information technology. We also discuss the controversial results and the possible origins yet to be resolved. In-depth study toward a comprehensive picture of the excited-state dynamics in perovskite nanocrystals may provide the key knowledge of the device operation mechanism, enlighten the direction for device optimization and stimulate the adventure of new conceptual devices.

Heterostructures based on diverse two-dimensional (2D) materials are effective for tailoring and further promoting device performance and exhibit considerable potential in photodetection. However, the problem of high-density thermionic carriers can be hardly overcome in most reported heterostructure devices based on type I and type II band alignment, which leads to an unacceptably small Iphoto/Idark and strong temperature dependence that limit the performance of photodetectors. Here, using the MoTe2/h-BN/MoTe2/h-BN heterostructure, we report the hole-dominated Fowler–Nordheim quantum tunneling transport in both on and off states. The state-of-the-art device operating at room temperature shows high detectivity of >108 Jones at a laser power density of

Solar-thermal energy storage using latent heat of phase change materials (PCMs) offers renewable penetration in wide range of smart applications. The limiting solar energy harvesting efficiency of existing photo-thermal dopant materials and their negative impact on thermal storage capacity have remained fundamental impediment to further advancement. Herein, we explore a phosphorene based bandgap engineered broadband photonic nanoheater for efficient thermal charging of solid-solid PCMs. In our devised composite system, we benefitted from the synergistic effect of highly efficient photonic energy harvesting characteristic of exfoliated phosphorene nanoflakes (PNF) and latent heat storage capability as well as encapsulating feature of PCM matrix. The solar-thermal energy storage efficiency of our developed materials exceeds 95 % even at lower phosphorene doping level (1 wt. %) and under full solar spectrum with improved latent heat storage capacity (150 J g−1). The achieved efficiency is highest among all photo-thermal storage materials and attributed to the intense and broadband solar absorbance of PNF featured by wide thickness distribution. Further, coating of developed solar heat storage material on fabric substrate has shown promising results toward real world applications.

The discovery of atomically precise nanoclusters is generally unpredictable, and the rational synthesis of nanoclusters guided by the theoretical design is still in its infancy. Here we present a de novo design of Au36(SR)24 nanoclusters, from theoretical prediction to experimental synthesis and characterization of their physicochemical properties. The crystal structure of an Au36(SR)24 nanocluster perfectly matches the simulated structural pattern with Au4 tetrahedral units along a two-dimensional growth. The Au36(SR)24 nanocluster indeed differs from its structural isomer whose kernel is dissected in an Au4 tetrahedral manner along a one-dimensional growth. The structural isomerism in the Au36(SR)24 nanoclusters further induces distinct differences in ultrafast electron dynamics and chirality. This work will not only promote the atomically precise synthesis of nanoclusters enlightened by theoretical science, but also open up exciting opportunities for underpinning the widespread applications of structural isomers with atomic precision.

The assembly of atomically precise metal nanoclusters offers exciting opportunities to gain fundamental insights into the hierarchical assembly of nanoparticles. However, it is still challenging to control the assembly of individual nanoclusters at a molecular or atomic level. Herein, we report the dimeric assembly of Au25 (PET)18 (PET=2-phenylethanethiol), where two Au25 (PET)18 monomers are bridged together by two Ag atoms to form the Ag2 Au50 (PET)36 dimer. The Ag2 Au50 (PET)36 dimer is a unique mesomer, which has not been found in any other chiral metal nanoclusters. Furthermore, the Ag2 Au50 (PET)36 dimer is distinct from the Au25 (PET)18 monomer in its optical, electronic, and catalytic properties. This study is expected to provide a feasible strategy to precisely modulate the assembly of metal nanoclusters with controllable structures and properties.

Next-generation polarized mid-infrared imaging systems generally requires miniaturization, integration, flexibility, good workability at room temperature and in severe environments, etc. Emerging two-dimensional materials provide another route to meet these demands, due to the ease of integrating on complex structures, their native in-plane anisotropy crystal structure for high polarization photosensitivity, and strong quantum confinement for excellent photodetecting performances at room temperature. However, polarized infrared imaging under scattering based on 2D materials has yet to be realized. Here we report the systematic investigation of polarized infrared imaging for a designed target obscured by scattering media using an anisotropic tellurium photodetector. Broadband sensitive photoresponse is realized at room temperature, with excellent stability without degradation under ambient atmospheric conditions. Significantly, a large anisotropic ratio of tellurium ensures polarized imaging in a scattering environment, with the degree of linear polarization over 0.8, opening up possibilities for developing next-generation polarized mid-infrared imaging technology., Photodetectors operating within scattering environment can be realized with anisotropic materials. Here, the authors report polarization sensitive photodetectors based on thin tellurium nanosheets with high photoresponsivity of 3.54 × 102 A/W, detectivity of ~3.01 × 109 Jones in the mid-infrared range and an anisotropic ratio of ∼8 for 2.3 μm illumination to ensure polarized imaging.

Herein, high-energy ball milling and hot pressing are employed to synthesize Al-15 vol.% μm Al2O3 (Al-MMC) and Al-15 vol.% nm Al2O3 (Al-MMNC) composites and the influence of reinforcement particle size (3 μm and 50 nm) on mechanical properties has been systematically studied. The as-prepared Al-MMNC samples rendered superior mechanical properties than Al-MMC and pure Al, with an improved yield strength and ultimate strength of 610 MPa and 784 MPa under quasistatic compression, respectively. Moreover, the flow stress of Al-MMC and Al-MMNC increased with increasing strain rate, and Al-MMNC exhibited higher flow stress than Al-MMC due to the smaller particle size. It is worth noting that the ultimate strength of Al-MMNC reached 963 MPa under the loading rate of 2200 s−1. Moreover, unlike previously reported Al-based nanocomposites, Al-MMNC exhibited strain hardening and strong strain rate sensitivity, which is highly desirable for engineering applications. Lastly, the ex-situ SEM analysis revealed the presence of microcracks and dimples on the fractured surface of Al-MMNC, which led to the ductile fracture mode under quasistatic compression. Moreover, the adiabatic shear under high strain rate loading has also been observed in Al-MMNC, but the high volume fraction nanoparticles inhibit adiabatic shear band development, and result in strain hardening and strong strain rate sensitivity.

The widespread utilization of phase change materials (PCMs) in thermal energy storage technologies is often limited by the shape instability, rigidity, low conductivity and lack of multi-driven capabilities. Therefore, the functionalization of PCMs in order to overcome the aforementioned issues has remained an elusive goal. Herein, we infiltrate a polyethylene glycol (PEG) based solid-solid PCM into the pores of carbon nanotube sponge (CNTS) to fabricate a dual form-stable, flexible and highly conductive phase change composites (PCCs). The developed PCCs undergo nanopore-confined solid-solid phase transition triggered by a low voltage or sunlight with high electro/photo to thermal energy storage efficiency (>94%). The reported energy conversion efficiencies for both electro and photo to thermal energy storage is highest among all functionalized PCCs and attributed to the excellent energy conversion/transfer performance of aligned carbon nanotubes (CNTs) network in the composite structure. In addition to extra shape stability, the solid-solid PCC present high axial thermal conductivity (2.4 W m−1k−1) as well as high-energy storage density 132 J g−1 which is close to solid-liquid PCCs. Therefore, this study provides routes towards the development of real-life applicable PCCs for thermal energy applications.

In this study, a novel nanofiber with improved antibacterial efficiencies was created by introducing TiO2 nanofibers and graphene oxide (GO) sheets into cellulose acetate (CA) nanofibers using an efficient electrospinning process. The morphologies and chemical composition of above nanocomposite were fully measured by SEM, FTIR and XRD measurements. The results demonstrated that TiO2 nanofibers and GO sheets have a uniform distribution in the CA nanofibers and these two additives also could improve hydrophilicity. TiO2/GO/CA@cotton exhibited high antibacterial activity with an inhibition rate higher than 95% against B. subtilis and B. cereus bacteria. Therefore, the proposed nanofiber is promising for the large-scale production of antibacterial nanofiber/cotton hybrid yarns for biomedical and antibacterial textiles applications.

Intrinsic linear polarized optics discovered in anisotropic two-dimensional (2D) materials has attracted intense interest for polarization-sensitive optical and optoelectronic applications, such as black phosphorous, ReSe2, etc. However, the lack of matured method to synthesize high-quality, large-scale and air-stable 2D materials with anisotropic properties, is still an obstacle for practical applications. Monolayer molybdenum disulfide (MoS2), which exhibits strong direct-band-gap light-harvesting properties, can be grown maturely. But unfortunately, MoS2 does not show linear dichroism owing to its in-plane isotropic crystalline symmetry. We, herein, for the first time, report on an artificial control of extrinsic linear polarized photoelectric effect in monolayer MoS2, by successfully controlling its anisotropic degree of in-plane crystal symmetry via artificially induced uniaxial tensile strain. Strong linear polarization-sensitive photodetection from visible to near-infrared range is realized for monolayer MoS2-based device, and the polarization anisotropic ratio can reach up over 2.0 under 4.5% strain. The observation is supported by combination of experiment-theory study on polarized Raman spectrum and optical absorption under gradually applied strains. Our results have demonstrated that the artificial-controlled symmetry reducing of MoS2 is a promising strategy to achieve high performance polarization photodetection. This method can also be extended to other 2D materials, which potentially opens up a new field to endow isotropic 2D materials with anisotropic functionalities by artificial structure engineering.

Middle East respiratory syndrome coronavirus (MERS-CoV) causes a severe acute respiratory syndrome-like illness with high pathogenicity and mortality due to the lack of effective therapeutics. Currently, only few antiviral agents are available for the treatment of MERS, but their effects have been greatly impaired by low antiviral activity, poor metabolic stability, and serious adverse effects. Therefore, the development of effective treatment for MERS is urgently needed. In this study, a series of heptad repeat 1 (HR1) peptide inhibitors have been developed to inhibit HR1/HR2-mediated membrane fusion between MERS-CoV and host cells, which is the major pathway of MERS-CoV-induced host infections. Particularly, peptide pregnancy-induced hypertension (PIH) exhibits potent inhibitory activity with IC50 of 1.171 μM, and its inhibitory effects can be further increased to 10-fold by forming a gold nanorod complex (PIH-AuNRs). In addition, PIH-AuNRs display enhanced metabolic stability and biocompatibility in vitro and in vivo and, therefore, effectively prevent MERS-CoV-associated membrane fusion. In summary, PIH-AuNRs represent a novel class of antiviral agents and have a great potential in treating MERS in the clinic.

Enhancing the light extraction efficiency is a prevalent but vital challenge for most solid-state lighting technologies, especially for deep ultraviolet light-emitting diodes (DUV-LEDs). In this paper, inspired by the microstructure of the butterfly's eye, we propose and fabricate a flexible fluoropolymer film (FFP film) to tackle this issue for all-mode, full-wavelength light extraction enhancement for most solid-state lighting technologies compatibly. The experimental results demonstrate that compared with one mounted with a smooth FFP film, the light output power of DUV-LED is enhanced up to 26.7% by mounting the FFP film with 325 nm radius nanocones at a driving current of 200 mA. Importantly, thanks to the super-flexible feature of the FFP film, it can both cover the top surface and sidewalls of the DUV-LED chip, leading to the improvement of transverse electric and transverse magnetic mode light extraction by 20.5 and 21.8%, respectively. Finite element analysis (FEA) simulations of the electric field distribution of DUV-LEDs with the FFP film reveal the underlying physics. The present strategy is proposed from the view of the packaging level, which is cost-effective, able to be manufactured at a large scale, and compatible with the solid-state lighting technologies.

Perovskite semiconductor nanocrystals (NCs) exhibit highly efficient optical gain, which is promising for laser applications. However, the intrinsic mechanism of optical gain in perovskite NCs, particularly whether more than one exciton per NCs is required, remains poorly understood. Here, we use two-dimensional electronic spectroscopy to resonantly probe the interplay between near-band-edge transitions during the buildup of optical gain in CsPbBr3 NCs. We find compelling evidence to conclude that optical gain in CsPbBr3 NCs is generated through stimulated emission from strongly interacting biexcitons. The threshold is largely determined by the competition between stimulated emission from biexcitons and excited-state absorption from single exciton to biexciton states. The findings in this work may guide future explorations of NC materials with low-threshold optical gain.

Gold-enhanced mechanical exfoliation method attracts broad interests in recent years, which has been widely used for preparing large-area and high-quality 2D single crystals. Even many calculations predict that there is strong interaction between Au film and the exfoliated 2D crystals, direct experimental evidence is still lacking. Here, we perform Raman spectroscopy measurements for few layer MoS2 with and without Au film underneath. The main peaks of MoS2 on Au film show no obvious change at higher frequency, however, the breathing and shear modes at low-frequency are suppressed, especially for breathing modes. In contrast, both breathing modes and shear modes can be detected on suspended MoS2 and the samples are transferred from Au film to SiO2/Si. These comparison results provide direct evidence for the existence of covalent-like quasi-bonding at the interface of Au film and the exfoliated MoS2 crystal. This MoS2/Au interface interaction presents a special pinning-effect for low-frequency rigid vibration. Similar pinning-effect is also discovered in WS2/Au system. Our work reports the suppression of low-frequency Raman modes of MoS2, WS2 on Au film, which will deliver new inspiration for studying other interactions between layered materials and solid surfaces.

We report the experimental observation of harmonic mode locking of a dual-wavelength all-fiber laser with different repetition rates. Dual-wavelength mode locking with individual fundamental repetition rates could be generated in the laser. By adjusting the intracavity polarization controller, harmonic mode locking of both wavelengths can be generated, and the difference of harmonic repetition rates is stable. This investigation not only enriches the nonlinear dynamics of mode-locked lasers, but also has potential applications related to the dual-comb based on a free-running fiber laser.

High-quality hexagonal BN (hBN) crystals, owing to their irreplaceable roles in new functional devices such as universal substrates and excellent layered insulators are exceedingly required in the field of two-dimensional (2D) materials. Although large-scale monolayer hBN crystals have been successfully grown on catalytic metals, the synthesis of large-area continuous hBN films with thickness in microns is challenging, hindering their applications at the mesoscopic level. Herein, we report the single-metal flux growth of centimeter-large, micron-thick, and high-quality continuous hBN films by balancing the grain size and coverage. The as-grown films can be readily exfoliated and transferred onto arbitrary substrates. Isotopically engineered hBN crystals can be obtained as well by the method. The narrow Raman line widths of the intralayer E2g mode peak (2.9 cm-1 for h11BN, 3.3 cm-1 for h10BN, and 7.9 cm-1 for hNaBN) and ultrahigh thermal conductivity (830 W m-1 K-1 for 4L h11BN) demonstrate high crystal quality and low defect density. Our results provide the foundation for the cost-efficient and lab-achievable synthesis of high-quality hBN films aimed at its mesoscopic applications.

We demonstrate that Ag(I) complex can fix bromide on the nanocrystal surface, reduce surface trap density, and as a result efficiently passivate the surface of CsPbBr3 nanocrystals. This passivation makes the photoluminescence (PL) intensity increase several times. The PL kinetics study clearly shows that the decay lifetime increased after the passivation. TEM and XPS analyses demonstrated the existence of Ag on the nanocrystal surface. In addition, we utilize single-particle spectroscopy combined with in situ light analysis to further confirm the PL enhancement effect. On the contrary, the passivation leads to the extraordinary photostability of CsPbBr3 nanocrystals, with 80% PL intensity retained after UV illumination for 5 days under ambient conditions.

The authors report mechanical strength of nuclear grade silicon carbide fiber reinforced silicon carbide matrix composite (SiCf-SiCm) tubing under several different stress states. The composite tubing was fabricated via a Chemical Vapor Infiltration (CVI) process, and is being evaluated for accident tolerant nuclear fuel cladding. Several experimental techniques were applied including uniaxial tension, elastomer insert burst test, open and closed end hydraulic bladder burst test, and torsion test. These tests provided critical stress and strain values at proportional limit and at ultimate failure points. Full field strain measurements using digital image correlation (DIC) were obtained in order to acquire quantitative information on localized deformation during application of stress. Based on the test results, a failure map was constructed for the SiCf-SiCm composites.

Recycled coarse aggregates, including crushed brick recycled coarse aggregate (CBRCA) and crushed concrete recycled coarse aggregate (CCRCA), are increasingly used as raw material in building materials. In fact, the morphological characteristics of recycled coarse aggregates take great effect on properties of materials. Therefore, this paper mainly investigates the morphological characteristics and physical properties of brick-concrete recycled coarse aggregate (BCRCA) composed of CBRCA and CCRCA. Morphological characteristics indexes of coarse aggregates including angularity, sphericity, texture and fractal dimension were described by digital image processing technique. The differences of morphological characteristic indexes among recycled coarse aggregates and natural crushed gravel coarse aggregate (NCGCA) were discussed. Results show that CBRCA has the highest void content, crushing index and water absorption among the four types of aggregates. Compared with NCGCA, recycled coarse aggregates have a higher angularity, lower sphericity and higher texture. The fractal dimension of recycled coarse aggregates is higher than NCGCA, indicating the complexity of shape of recycled coarse aggregates. Among the recycled coarse aggregates, CBRCA has the highest angularity and lowest sphericity, and CCRCA has the highest texture. The angularity and texture are significantly influenced by aggregate types. The sphericity and flatness ratio, as well as the angularity and texture have good positive correlation. The fractal dimension and elongation ratio, as well as the fractal dimension and sphericity have negative correlation. By testing two-dimensional indexes including fractal dimension and elongation ratio can easily reflect the morphological characteristics of coarse aggregates. When recycled coarse aggregates is used in building materials, the morphological characteristics should be carefully considered.

Hierarchically porous electrodes made of electrochemically active materials and conductive additives may display synergistic effects originating from the interactions between the constituent phases, and this approach has been adopted for optimizing the performances of many electrode materials. Here we report our findings in design, fabrication, and characterization of a hierarchically porous hybrid electrode composed of α-NiS nanorods decorated on reduced graphene oxide (rGO) (denoted as R-NiS/rGO), derived from water-refluxed metal–organic frameworks/rGO (Ni-MOF-74/rGO) templates. Microanalyses reveal that the as-synthesized α-NiS nanorods have abundant (101) and (110) surfaces on the edges, which exhibit a strong affinity for OH− in KOH electrolyte, as confirmed by density functional theory-based calculations. The results suggest that the MOF-derived α-NiS nanorods with highly exposed active surfaces are favorable for fast redox reactions in a basic electrolyte. Besides, the presence of rGO in the hybrid electrode greatly enhances the electronic conductivity, providing efficient current collection for fast energy storage. Indeed, when tested in a supercapacitor with a three-electrode configuration in 2 M KOH electrolyte, the R-NiS/rGO hybrid electrode exhibits a capacity of 744 C g−1 at 1 A g−1 and 600 C g−1 at 50 A g−1, indicating remarkable rate performance, while maintaining more than 89% of the initial capacity after 20 000 cycles. Moreover, when coupled with a nitrogen-doped graphene aerogel (C/NG-A) negative electrode, the hybrid supercapacitor (R-NiS/rGO/electrolyte/C/NG-A) achieved an ultra-high energy density of 93 W h kg−1 at a power density of 962 W kg−1, while still retaining an energy density of 54 W h kg−1 at an elevated working power of 46 034 W kg−1.

Phase change materials (PCMs) have been extensively characterized as constant temperature latent heat thermal energy storage (TES) materials. Nevertheless, the widespread utilization of PCMs is limited due to the flow of liquid PCMs during melting, phase separation, supercooling and low heat transfer rate. In order to overcome these inherent problems and to improve thermo-physical properties, the confinement of PCMs at the nanoscale has been identified as a versatile strategy, which ensures the encapsulation of PCMs in much smaller nano-containers. Such strategies including core–shell, longitudinal, interfacial and porous confinement have been widely presented in recent years to efficiently encapsulate PCMs in nanospaces and are presenting attractive ways to enhance thermal performance. This review summarizes the recent advancement and critical issues of nanoconfinement technologies of PCMs from the point of view of material design. In addition, the potential applications of nanoconfined PCMs in diverse fields, including energy conversion and storage, thermal rectification and temperature controlled drug delivery systems, are presented in detail. Finally, the major drawbacks associated with nanoconfined PCMs and their prospective solutions are also provided.

In order to improve the solidification performance of latent heat thermal energy storage system, a new trapezoidal longitudinal outer fin distributed by Fibonacci sequence is proposed due to the low thermal conductivity of phase change material. Firstly, the solidification behavior (temperature distribution, solid fraction, and solidification time) of three trapezoidal fins and traditional quadrilateral fin are compared by numerical simulation. The fin design with the highest improvement in solidification performance is selected and the dynamic temperature analysis is carried out. The Fibonacci sequence is introduced into the fin distribution and the effect of different longitudinal fin arrangements on solidification performance is analyzed. In addition, Response surface method is used to investigate the influence of geometric parameters of the trapezoidal fin based on Fibonacci sequence arrangement, and the optimal structure is obtained after optimization. The results show that the solidification time of phase change material after using modified trapezoidal fin with Fibonacci sequence is shortened by 45.28% compared with the traditional quadrilateral fin. Finally, the temperature difference between the inner tube cold fluid and the phase change material is greater than 20 K, which can ensure the excellent solidification performance.

Coherent exciton-phonon coupling in CdSe/ZnS nanocrystals have been investigated by temperature-dependent two-dimensional electronic spectroscopy (2DES) measurements. Benefiting from the ability of 2DES to dissect assembles in nanocrystal films, we have clearly identified experimental evidences of coherent coupling between exciton and phonon in CdSe/ZnS nanocrystals. In time domain, 2DES signals of excitonic transitions beat at a frequency resonant to a longitudinal optical phonon mode; in energy domain, phonon side bands are distinct at both Stokes and anti-Stokes sides. When temperature increases, phonon-induced exciton dephasing is observed with dramatic broadening of homogeneous linewidth. The results suggest exciton-phonon coupling is essential in elucidating the quantum dynamics of excitonic transitions in semiconductor nanocrystals.

A novel family of Ga2S3–Sb2S3–XI (XI= PbI2, CsI, AgI) was investigated to understand the role of metal halides and exploit new chalco-halide glasses for infrared optics. The dependence of the thermal properties, infrared optical properties, and structural information of the novel family on different metal–iodines was investigated. Results showed that metal halides increase the glass stability but decrease the glass network connectivity. The compositional dependence of the short-wave cut-off edge is associated with the electronegativity difference between the cations and anions of the metal halides. Raman study showed that the metal–iodine modified the glass structure mainly through the iodide content, and the cations dissolved in the glass network mostly as charge compensators for the aperiodic network. For the glasses in the series Ga2S3–Sb2S3–XI–Dy3+, Dy3+ emission increased in the PbI2- and CsI-doped glasses but decreased in the AgI-doped glass due to the combined effect of dysprosium and oxygen. For all that, these novel glasses are highly promised for use in infrared optics. This article is protected by copyright. All rights reserved.

Tm3+-doped Ge−Ga−S−AgI chalcogenide glasses with the addition of La2S3 have been fabricated. The effects of La2S3 on the glass structure and the Tm3+-doped infrared emission property have been discussed. The results show that incorporation of La in the Ge−Ga−S−AgI glass matrix induces the dissociation of Ge–Ge metal bonds and transforms the [S3Ge–GeS3] bonds to GeS4 tetrahedra. A new peak at about 230 cm−1 is detected in Raman spectra and a redshift at the visible absorbing cut-off edge is observed with introduction of La2S3. The La2S3-modified glasses exhibit enhanced emission intensity in both 1.46 μm and 1.8 μm emission bands and have larger solubility of rare-earth because of substitution mechanism of Tm3+ for La3+ ions. The introduction of high Tm concentration into glasses induces the attenuation of emission intensity. This phenomenon is correlated with the recurrence emission quenching effect.

Purpose U3Si2 is under investigation as an accident tolerant fuel due to its advantageous thermo-physical properties, including; high uranium density, high thermal conductivity, and high melting temperature. However, mechanical data available for the fuel is limited. Vickers micro-indentation characterization was used to evaluate the mechanical properties of U3Si2 specimens of varying microstructure in order to determine the effect of sintering conditions on mechanical behavior. Methods A chemical etchant was applied in order to observe grain boundaries in the material. The microstructure surrounding the indentations was investigated using polarized light optical microscopy imaging, scanning electron microscopy imaging, and elemental analysis techniques. Results All U3Si2 samples cracked in a brittle manner with cracks adjacent to the indents. Cracks tend to propagate through grains rather than along grain boundaries. The Vickers hardness of the U3Si2 samples was between 414 HV and 678 HV. High porosity in the sample was associated with a lower hardness. The toughness of the samples was roughly the same amongst all U3Si2 samples, ∼1 MPa√m. Conclusions The hardness and fracture toughness of U3Si2 was found to be comparable to that of unirradiated UO2. Given that UO2 has a history of good experience in the nuclear industry, U3Si2's comparable cracking behavior and mechanical properties speak favorably for its anticipated performance in reactor.

A novel solid-to-solid phase change composite brick was prepared by combination of polyurethane (PU) and pitch-based graphite foam (PGF). The carbonaceous support, which can be used for mass production, not only greatly improves the thermal conductivity but promote electro-to-heat conversion efficiency of organic phase change materials (PCMs). Our composite retained the enthalpy of PCM and exhibited a greatly reduced supercooling temperature. The novel composite was investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and scanning electron microscope (SEM). The enthalpy of polyurethane has increased about 8.6% after infiltrating into graphite foam. The composite was very stable during thermal cycle test, and the electro-to-heat conversion efficiency achieves to 85% at lower voltages (1.5–1.8 V), which can vastly reduce energy consumption. The as-prepared composite was used in a wear layer to test its performance comparing with normal fabric.

Surface dielectric barrier discharge (SDBD) plasma actuators has been widely used for enhanced aerodynamics. In this paper, several different surface conductivity and frequency configurations, i.e., high conductivity surface and low supply frequency were chosen for the SDBD plasma actuator. And an improved simulation model with fewer mesh units and better convergence was proposed in this paper. The Simulated results show that surface conductivity have a significant impact on the performance of actuators, such as electric field distribution before discharge. The effects also verified by experiments.

For the realization of bioassay with complex fluidic manipulation and logic operation on lab-on-a-disc platform, we present an active integrated centrifugal microfluidic chip based on the on-board control of wax valves within a multilayer complex chip. The multilayer hybrid structure including a microfluidic layer and a printing circuit board (PCB) layer utilizes the digital logic of electronic system to control the logic of liquid flow in microfluidic layer. The coupling mechanism between both layers is based on heat transfer, namely, the heating resistors in PCB layer are used to melt and open the paraffin wax valves in microfluidic layer. Without the limitation of surface tension-dependent valves, the application of active valve could be freely designed, which can largely extend the ability of integration on microfluidic chip. Many complex functional units including liquid sequential loading and switching of liquid flow are demonstrated. As an application, we also present a multilayer complex chip for plasmid DNA extraction based on our platform. In a word, our active centrifugal microfluidic platform provides a solution for the integration of complex bioassay on rotating disc, which has great potential in the applications of point-of-care diagnostics (POC).

Phase change materials have important significance for thermal energy storage, but their low heat conductivity is the main problem affecting energy storage. In order to improve the solidification performance of the triplex-tube thermal energy storage system, a new type of triangular fin is proposed in this paper. Firstly, longitudinal triangular fins with different distributions are added to the triplex-tube thermal energy storage system to compare the solidification performance with that of traditional rectangular fin. The solid distribution and temperature evolution of the fins with different distributions were studied by numerical simulation in detail. Compared with the traditional rectangular fin, the solidification time of the system can be reduced by up to 30.98% by the optimized triangular fin. Secondly, the temperature evolution law of different positions in this system is emphatically studied, so as to prove the optimization degree of the fin to the solidification behavior of the energy storage system. Then the influence of the geometry parameters, triangular fin airfoil, the temperature of the tube cooling fluid on the solidification performance are discussed. Finally, the effect of the connecting position between the new triangular fin to the inner or outer tubes on the solidification performance of the system is discussed.

Quantum dephasing of excitonic transitions in CsPbBr3 nanocrystals has been studied using two-dimensional electronic spectroscopy at cryogenic temperatures. The exciton–phonon interactions for acoustic and optical modes exhibit different effects on the coherent dynamics of excitonic transitions. The homogeneous linewidth shows a proportional dependence on the temperature, suggesting the primary dephasing channel of the elastic scattering between exciton and acoustic modes. The exciton–optical mode interaction is manifested as the beatings of off-diagonal signals in the population time domain at the frequencies of 29 and 51 cm−1, indicating phonon replicas of excitonic transitions arising from coherent exciton–phonon interaction. The insight information of exciton homogeneous broadening in perovskite nanocrystals is essential for the potential application of quantum light sources.

Based on a comprehensive description of the conservation of momentum, mass and charge, as well as the global dynamics involving ion and proton reactions, a three-dimensional transient model for zincnickel single flow battery considering side reactions of hydrogen evolution and oxygen evolution was established. The accuracy of the model is verified by experiments. The effects of current density, electrolyte flow rate, initial ion concentration, temperature and electrode porosity on the side reactions of hydrogen evolution and oxygen evolution were investigated. The effects of side reactions on the activation polarization and concentration polarization of the battery were studied by comparing the two cases of whether side reactions were considered or not. The results show that the reaction rate of hydrogen evolution and oxygen evolution can be effectively reduced by reducing the applied current density, ambient temperature or increasing the flow rate of electrolyte. Increasing the initial concentration of hydroxyl ions inhibited the occurrence of hydrogen evolution side reaction, but also promoted the occurrence of oxygen evolution side reaction. As the porosity of the positive electrode increases, the reaction rate of the side reaction of oxygen evolution and the oxygen concentration in the positive electrode area gradually decrease. In the later stage of charging, when the shielding effect of oxygen bubbles on the positive reaction interface is not considered, compared with the case without considering the side reactions, the positive electrode activation polarization is larger when considering the side reaction.

Owing to the high energy density of phase change materials, latent heat storage systems have been an effective strategy for the improvement of energy efficiency. The severe limitations of their extensive application are the potential leakage and low thermal conductivity. Herein, we developed a facile dual-encapsulation method to solve the abovementioned problems in the phase change composite composed of octadecanol, a high thermal/electrical conductive macroporous graphite foam and a thin waterborne polyurethane (WPU) film. After dual-encapsulation, the thermal conductivity of the composite was 20 times higher than that of pure phase change material (PCM) octadecanol. As a result, the composite exhibited a reduced supercooling degree and rapid thermal energy charging behaviors, as well as electro-to-heat conversion ability. This study gives a new perspective for the synergistic enhancement of both the thermal and electric conductivity of functional PCMs for thermal energy storage and conversion.

Post-surgery mesh infections are one of the most common complications of hernia repair at the interface of implant materials and tissue, because high doses of antimicrobial agents are toxic and low doses of antibacterial agents are ineffective, with no good clinical solution currently available. To reduce the infection rates after mesh implantation, we designed a "one-pot synthesized" mesoporous silica nanoplatform consisting of levofloxacin (Lev) and silver (Lev@MSN@Ag) composites with poly-l-lactide (PLLA) electrospun fibrous membranes via blending electrospinning. With advances in the combined antibacterial agents Lev and Ag at a low dosage for the treatment of drug-resistant bacterial infections (28 μg mL-1 Lev and 12 μg mL-1 Ag) with a concentration of 5 × 105 CFU mL-1, the composite electrospun fibers act as a carrier for drug-loading and have an antibacterial effect over 8 weeks. Lev@MSN@Ag-PLLA fibers showed a superior antibacterial effect on drug resistant strains in the in vitro test at low doses of antibacterial agents. Further, the in vivo study showed that Lev@MSN@Ag-PLLA fibers significantly inhibited bacterial growth and infection over 8 weeks through the combined effect of low dosage antibacterial drugs. In conclusion, the Lev@MSN@Ag-PLLA fibers provided an advanced combined antibacterial nanoplatform of low dosage for the treatment of drug-resistant bacterial infections.

Based on COMSOL Multiphysics software, the geometric model of graphene structure is set on the two-dimensional plane, and the thickness of graphene layer is set at 400 nm. The real and imaginary parts of the refractive index of graphene are defined. Then, the Ag and Au films are coated on both sides of graphene to form the Ag/G/Ag and Au/G/Au sandwich structures, respectively. In addition, the electric field modes between 300 nm and 600 nm are obtained by parameterized scanning calculation of the incident wavelength λ. At the same time, adsorption, scattering and extinction spectra are plotted. Results indicated that the maximum field strength of both the Ag/G/Ag and Au/G/Au sandwich structures are nearly doubled as compared to the intrinsic graphene. Finally, the adsorption, scattering and extinction properties are discussed. It is concluded that the resonance absorption peaks can be adjusted and improved by Ag/Au modification. The strongest plasma resonance mode shifts towards high energy. Moreover, Ag/G/Ag has stronger surface plasmon resonance effect than that of Au/G/Au structure.

Integrated silicon-based plasmonic photodetectors have attracted more and more attention recently, due to their potential applications in THz bandwidth. In this paper, by utilizing a simplified two-step lithography process, the photoconductive detector is fabricated with the core structure of plasmonic slot waveguide in two symmetric metallic slabs as microwave electrodes to integrate with mechanically exfoliated graphene. The 3-dB bandwidth of the graphene-on-plasmonic slot waveguide photodetector is exceeded 120 GHz under the theoretical calculation, and the measured bandwidth is still beyond 70 GHz due to the lack of larger-bandwidth equipment. High-speed data reception is demonstrated for 72 Gbit/s NRZ and 64 Gbit/s PAM-4 signals with a BER below 15% soft-decision FEC threshold. Based on the enhanced interactions of light and graphene induced by the subwavelength confinement from the plasmonic structure, the responsivity of 0.13 A/W is achieved under the condition of the 7-μm long detection zone and the 0.4-V bias voltage. With the advantages of ultra-compact, high-speed, large-bandwidth and compatible with the CMOS process, our photodetector has the potential to be used in high-speed optical interconnection, terahertz transmission and terahertz communication.

Magnetism in 2D has long been the focus of condensed matter physics due to its important applications in spintronic devices. A particularly promising aspect of 2D magnetism is the ability to fabricate 2D heterostructures with engineered optical, electrical, and quantum properties. Recently, the discovery of intrinsic ferromagnetisms in atomic thick materials has provided a new platform for investigations of fundamental magnetic physics. In contrast to 2D CrI3 and Cr2 Ge2 Te6 insulators, itinerant ferromagnetic Fe3 GeTe2 (FGT), which has a larger intrinsic perpendicular anisotropy, higher Curie temperature (TC ), and relatively better stability, is a promising candidate for achieving permanent room-temperature ferromagnetism through interface or component engineering. Here, it is shown that the ferromagnetic properties of FGT thin flakes can be modulated through coupling with a FePS3 . The magneto-optical Kerr effect results show that the TC of FGT is improved by more than 30 K and that the coercive field is increased by ≈100% due to the proximity coupling effect, which changes the spin textures of FGT at the interface. This work reveals that antiferromagnet/ferromagnet coupling is a promising way to engineer the magnetic properties of itinerant 2D ferromagnets, which paves the way for applications in advanced magnetic spintronic and memory devices.

Anode flooding is one of the critical issues in developing a proton exchange membrane (PEM)-based electrochemical hydrogen pump. Improving the hydrophobicity of the gas diffusion layer (GDL) has been studied as an approach to mitigating anode flooding in electrochemical pumps. A mixture of Nafion™ and oxidized carbon nanotubes (O-CNT) has been applied to the porous gas diffusion medium in the hydrogen pump cell. The coating renders the GDL hydrophobic with an effective contact angle of 130°. Electrochemical pump testing has shown that, with the help of the coating, the flood-recovery performance of the hydrogen pump was greatly improved. A hydrogen pump cell with an uncoated GDL was not able to recover from a flooded state, while a hydrogen pump cell with a coated GDL was able to recover its performance in about 100 s.

Acoustic metamaterials with artificial microstructures are attractive to realize intriguing functions, including efficient waveguiding, which requires large impedance mismatches to realize total side reflection with negligible transmission and absorption. While large impedance mismatch can be readily realized in an air environment, acoustic waveguiding in an underwater environment remains elusive due to insufficient impedance mismatch of state-of-the-art metamaterials. Here, a superhydrophobic acoustic metasurface of microstructured poly(vinylidene fluoride) membrane, referred to as a "meta-skin" insulator, which is able to confine acoustic waves in an all-angle and wide spectrum range due to tremendous impedance mismatch at stable air/water interfaces, viz., the Cassie-Baxter state is demonstrated. By utilizing the meta-skin insulator with broadband and high throughput, orbital-angular-momentum multiplexing at a high spectral efficiency and binary coding along large-angle bending channels for bit-error-free acoustic data transmission in an underwater environment are demonstrated. Very different from optical and/or electrical cable communications, acoustic waves can be simply and effectively coupled into remote meta-skin acoustic fibers from free space, which is technologically significant for long-haul and anti-interference communication. This work can enlighten many fluidic applications based on efficient waveguiding, such as in vivo ultrasound medical treatment and imaging.