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The capture efficiency describes the capability of a sink, such as a grain boundary (GB), dislocation, and void, to absorb point defects (PDs). The bias defines the difference in capture efficiency between the absorption of a vacancy and dumbbell at a sink. Complete kinetic information on PDs, including diffusion barriers and diffusion orientations, as well as accurate saddle points, are needed to determine the capture efficiency and bias at a sink accurately, which is computationally demanding. In the present study, the Self-Evolving Atomistic Kinetic Monte Carlo (SEAKMC) method was used to investigate the defect dynamics of PDs near different types of grain boundaries (GBs) (with both 〈100〉 and 〈110〉 families) accurately in body-centered cubic (BCC) iron (Fe). The capture efficiency, sink strength, and bias factor of different types of GBs were determined in Fe, which, different from traditional rate theory estimation, showed a distinct capture efficiency, sink strength, and bias in different GBs. The results demonstrate a strong positive correlation between the capture efficiency and the GB strain width, instead of the GB misorientation, GB energy, or GB-PD binding energy, which have been investigated previously. This work provides valuable insight into the radiation-induced microstructural evolution of GBs.

The effect of the volume fraction of 3D-metal matrix composites (MMC) framework on the compressive properties of 3D interpenetrating hierarchical ZrO2-toughened Al2O3 particle (ZTAp)/40Cr steel composites was investigated. The results showed that the compressive properties of the material tended to decrease as the volume fraction of 3D-MMC framework increased. The composite with 35 vol.% 3D-MMC had a yield strength of 1455.2 MPa and compressive strength of 1612.8 MPa, which occurred at a strain value of 5.6%. Compared to the homogeneously dispersed composite material, the composite with 35 vol.% 3D-MMC had a 144.7% higher yield strength, which occurred at a 20% higher strain. An analysis of the cracks inside the material revealed that the crack was hindered and deflected by the matrix during propagation, which lengthened the crack propagation path and consumed more energy, thus leading to toughening. The results indicated that 3D interpenetrating hierarchical structure had a strengthening and toughening effect on ZTAp/40Cr composites.

Zero-macroscopic-strain deformation twinning (ZMS-DT) is widely observed in many face-centred-cubic (FCC) metals and alloys. However, the driving force of ZMS-DT is a controversial issue and has no...

This study aimed to fabricate micro-nano bioactive glass (MNBG) scaffolds loaded with chemotherapeutics and siglec-15 monoclonal antibody with bone repair capability and high-active drug loading capability for postoperative treatment of osteosarcoma. Bioactive glass (BG) particles were incorporated with siglec-15 mAb and gemcitabine through mesopores and calcium ions on the surface. Dendritic cells (DCs) were treated with siglec-loaded BGs and gemcitabine. RT-qPCR analysis was conducted to detect DJ-1 and PTEN mRNA levels, CCK-8 technology to detect cell activity, and flow cytometry to detect cell apoptosis. Rats were administrated with siglec-15-MNBG composite scaffolds with/without gemcitabine. 3D printing was used to determine adhesion strength of each group. Administration of MNBG scaffold decreased the expression of PTEN and up-regulated expression of DJ-1 when inducing cell apoptosis. Combined treatment with gemcitabine augmented adhesion of material and enhanced phosphorylation activity of p-AKT, mitigating the inhibitory effect of scaffold loaded with siglec-15 on p-AKT protein expression. Collectively, MNBG scaffold loaded with siglec-15 might promote bone regeneration and incorporate with chemotherapeutic drugs to suppress tumor development and promote apoptosis through PTEN/PI3 K pathway. These findings provide a novel insight into postoperative treatment of osteosarcoma and help development of tumor immunotherapy/bone repair integrated materials.

As one of the core equipment components of oil and gas drilling rig, derrick is also the main heavy-duty component. Working environment of derrick is quite bad, the material for which should have not only high strength, but also good plasticity, toughness and weldability. In this paper, the chemical composition, microstructure, tensile properties, impact properties and hardness of three typical Q690D high strength low alloy steel manufactured from different methods were studied. The application feasibility of Q690 for drilling derrick manufacture was analyzed. The experimental results show that the carbon equivalent, tensile properties and impact absorption energy of Q690D steel with different thickness obtained by TMCP and Q-T process were obviously higher than the requirement of corresponding standard. TMCP Q690D steel had better toughness, lower carbon content and carbon equivalent, and its micro-structure was granular bainite. Carbon content of Q-T Q690D steel plate was relatively higher than that of TMCP Q690D, and the toughness was slightly lower than that of TMCP Q690D. The microstructure Q-T Q690D was tempered sorbite, and there was certain zonal segregation in center part. The thickness of steel plate used in derrick was usually less than 40 mm, whose manufacturing technology of Q690D was mature. There is broad application prospect in the field of drilling equipment. The application of Q690D for drilling equipment not only improve the strength grade of equipment materials, but also help to optimize the design of components and ensure service safety.

With the increase of drilling depth, the mechanical properties of H-section steel used in drilling platform are more and more demanding. In this paper, the strength, low temperature impact toughness, plasticity, micro-hardness and microstructure of 500MPa hot rolled H-section steel produced by TMCP process were analyzed, and the strengthening mechanism was also studied. The results show that flanges of TMCP hot rolled H-section steel had the best strength and toughness, while the yield strength at web and R Angle was reduced to 91% and 78% of the flange, respectively. The impact toughness at -40°C of web and R Angle was reduced to 86% and 38% of the flange , and the micro-hardness reduced to 91% and 85% of the flange, respectively. The main strengthening mechanism of the TMCP hot rolled H-section steel is fine-grain strengthening, the carbonitride of V precipitation strengthening and surface bainite transformation strengthening.

The all-inorganic nature of CsPbI3 perovskites allows to enhance stability in perovskite devices. Research efforts have led to improved stability of the black phase in CsPbI3 films; however, these strategies-including strain and doping-are based on organic-ligand-capped perovskites, which prevent perovskites from forming the close-packed quantum dot (QD) solids necessary to achieve high charge and thermal transport. We developed an inorganic ligand exchange that leads to CsPbI3 QD films with superior phase stability and increased thermal transport. The atomic-ligand-exchanged QD films, once mechanically coupled, exhibit improved phase stability, and we link this to distributing strain across the film. Operando measurements of the temperature of the LEDs indicate that KI-exchanged QD films exhibit increased thermal transport compared to controls that rely on organic ligands. The LEDs exhibit a maximum EQE of 23 % with an electroluminescence emission centered at 640 nm (FWHM: ≈31 nm). These red LEDs provide an operating half-lifetime of 10 h (luminance of 200 cd m-2 ) and an operating stability that is 6× higher than that of control devices.

Herein is developed a ternary heterostructured catalyst, based on a periodic array of 1D TiN nanotubes, with a TiO2 nanoparticulate intermediate layer and a In2O3-x(OH)y nanoparticulate shell for improved performance in the photocatalytic reverse water gas shift reaction. It is demonstrated that the ordering of the three components in the heterostructure sensitively determine its activity in CO2 photocatalysis. Specifically, TiN nanotubes not only provide a photothermal driving force for the photocatalytic reaction, owing to their strong optical absorption properties, but they also serve as a crucial scaffold for minimizing the required quantity of In2O3-x(OH)y nanoparticles, leading to an enhanced CO production rate. Simultaneously, the TiO2 nanoparticle layer supplies photogenerated electrons and holes that are transferred to active sites on In2O3-x(OH)y nanoparticles and participate in the reactions occurring at the catalyst surface.

Colloidal quantum dot (CQD) solar cells are solution-processed photovoltaic devices that exhibit promise in harvesting the infrared solar spectrum. Solid-state ligand exchange is the method employe...

Pressurized oxy-combustion is a promising technology for carbon capture, utilization, and storage. For the captured CO2 to be used for enhanced oil recovery or stored in geological formations, flue gas impurities, including residual O2 in the CO2 stream, must be purified to meet the purity specifications. A catalytic approach to reducing residual O2 with CH4 was investigated in this study. Five CoMn- and Cu-based catalysts were synthesized or acquired, and a reverse-flow fixed-bed reactor was used to assess their performance for O2 removal from a simulated oxy-combustion flue gas at 15 bar. The impacts of the operating parameters on O2 removal, such as temperature, gas hourly space velocity, O2/CH4 ratio, and gas pressure, were investigated. Among the tested catalysts, the two CoMn catalysts were superior in both activity and selectivity, with the reaction lighting off at about 350 °C and achieving 99% O2 removal at about 500 °C. The kinetics of the catalytic reaction is discussed, and the Mars–van Krevelen redox mechanism is deemed valid for describing the reaction pathway for the top-performing CoMn catalysts. The catalytic reaction was determined to be first order in CH4 and zero order in O2 under the test conditions.

The chirality feature of C1 and C3 boron subphthalocyanines (BsubPcs) is an attractive property in material science and supramolecular chemistry. Normally in the field, enantiomeric mixtures are separated through a standard process. The goal of this study was to determine if the mixture of BsubPc enantiomers could form a mixed alloyed composition in the solid state, which is very relevant to their potential application in the organic electronic field. We present the synthesis and physical characteristics of a selection of four chiral BsubPc mixtures. These BsubPcs are specifically trichlorinated and trifluorinated in the periphery, such as Cl-βF3BsubPc, Cl-αF3BsubPc, Cl-βCl3BsubPc and Cl-αCl3BsubPc. The isomeric (C1/C3) ratios of each BsubPc were determined by NMR. Single-crystal XRD of all four BsubPc mixtures showed that the C1 and C3 isomers co-crystallized within their respective lattices forming solid-state mixed alloyed compositions. The structures of Cl-αF3BsubPc and Cl-βF3BsubPc crystallized in the same lattice as Cl-BsubPc, with some expansion of the unit cell volume, while the trichlorinated BsubPcs did not due to the large van der Waals radii of the chlorine atoms. This set of mixed alloyed BsubPcs was also integrated into organic solar cells/photovoltaics (OSCs/OPVs) as both non-fullerene electron acceptors and as electron donors. It was confirmed that these BsubPc isomers/enantiomers are applicable in OPVs as mixed alloyed compositions, with more promising functionality as non-fullerene electron acceptors given their significant contribution to the EQE spectra. Further molecular engineering of these materials will be made to enhance their OPV performance and to explore their bifunctional charge carrier mobility roles.

Colloidal quantum dot (CQD) solar cells composed of ionic halide passivated active layers benefit from improved passivation and high carrier mobility because of short interparticle distance. Howeve...

Bias-stress instability has been a challenging problem and a roadblock for developing stable p-type organic field-effect transistors (OFETs). This device instability is hypothesized because of electron-correlated charge carrier trapping, neutralization, and recombination at semiconductor/dielectric interfaces and in semiconductor channels. Here, in this paper, a strategy is demonstrated to improve the bias-stress stability by constructing a multilayered drain electrode with energy-level modification layers (ELMLs). Several organic small molecules with high lowest unoccupied molecular orbital (LUMO) energy levels are experimented as ELMLs. The energy-level offset between the Fermi level of the drain electrode and the LUMOs of the ELMLs is shown to construct the interfacial barrier, which suppresses electron injection from the drain electrode into the channel, leading to significantly improved bias-stress stability of OFETs. The mechanism of the ELMLs on the bias-stress stability is studied by quantitative modeling analysis of charge carrier dynamics. Of all injection models evaluated, it is found that Fowler-Nordheim tunneling describes best the observed experimental data. Both theory and experimental data show that, by using the ELMLs with higher LUMO levels, the electron injection can be suppressed effectively, and the bias-stress stability of p-type OFETs can thereby be improved significantly.

In this study, we designed a surface phase-matched transmission enhancement top electrode-Ag/indium tin oxide (ITO) structure for highly efficient and aesthetic semitransparent organic photovoltaics (ST-OPVs). The purposed highly transparent back electrodes (Ag/ITO) could selectively decrease visible reflection and increase transparency accordingly. By altering the thicknesses of the Ag and ITO layers, we could control the transmittance curve and increase the transparency of the ST-OPV devices. Devices based on PTB7-Th:IEICO-4F and PM6:Y6:PC71BM displayed outstanding performance (8.1 and 10.2%, respectively) with high photopic-weighted visible light transmittance (36.2 and 28.6%, respectively). The outstanding visible and near-infrared light harvesting of PM6:Y6:PC71BM further allowed a new application: double-sided energy harvesting from solar and indoor illumination. The simple optical design of a top electrode displaying high transparency/conductivity has a wide range of potential applications in, for example, greenhouse photovoltaics, tandem cells, and portable devices.

Colloidal quantum dot (QD) solids are emerging semiconductors that have been actively explored in fundamental studies of charge transport1 and for applications in optoelectronics2. Forming high-quality QD solids—necessary for device fabrication—requires substitution of the long organic ligands used for synthesis with short ligands that provide increased QD coupling and improved charge transport3. However, in perovskite QDs, the polar solvents used to carry out the ligand exchange decompose the highly ionic perovskites4. Here we report perovskite QD resurfacing to achieve a bipolar shell consisting of an inner anion shell, and an outer shell comprised of cations and polar solvent molecules. The outer shell is electrostatically adsorbed to the negatively charged inner shell. This approach produces strongly confined perovskite QD solids that feature improved carrier mobility (≥0.01 cm2 V−1 s−1) and reduced trap density relative to previously reported low-dimensional perovskites. Blue-emitting QD films exhibit photoluminescence quantum yields exceeding 90%. By exploiting the improved mobility, we have been able to fabricate CsPbBr3 QD-based efficient blue and green light-emitting diodes. Blue devices with reduced trap density have an external quantum efficiency of 12.3%; the green devices achieve an external quantum efficiency of 22%. A solution-based ligand-exchange strategy enables the realization of close-packed quantum dot solid films with near-unity photoluminescence quantum yield and high charge carrier mobility.

Metal halide perovskite absorbers with wide bandgaps (1.6–1.7 eV) that are suitable for tandem devices typically require high Br concentrations; this renders the material prone to halide segregation and degradation. Inorganic, bromine-free CsPbI3 has a wide bandgap of 1.7 eV and does not suffer from halide segregation; however, these active layers are not stable at room temperature. Here, we report a method to create stable tetragonal perovskites with a bandgap near 1.7 eV: we add small amounts of large A-site cations having ionic radii between 272 and 278 pmdimethylammonium (DMA) and guanidinium (Gua)into the crystal lattice. When we deploy perovskites using mixed Cs and these large organic cations, we achieve stable, wide bandgap perovskites with power conversion efficiencies of 15.2% and VOC of 1.19 V. This study extends materials selection for wide bandgap Cs-based perovskites.

Low-dimensional copper halides with high luminance have attracted increasing interest as heavy-metal-free light emitters. However, the optical mechanisms underpinning their excellent luminescence r...

During acidizing process in a gas field, leakage of 80SS anti-sulfur tubing occurred.The main reasons for failure of the tubing have been investigated based on analysis techniques of chemical composition analysis,Optical Microscopy (OM), Scanning Electron Microscope (SEM), Energy Dispersive Spectrometer (EDS) , X-ray Diffraction (XRD) and mechanical test. The results show that composition and mechanical properties of the tubing were all in accordance with the corresponding requirements of API Spec 5CT standards. Furthermore,leakage of tubing from inner wall was caused by combined impacts of acid corrosion, H2S corrosion, low PH value, high temperature and a certain pressure. Meanwhile, Low concentration of corrosion inhibitor was also one of the factors of corrosion perforation.

In view of the external thread fracture during casing running in a well in Xinjiang Oilfield, the failure reasons of thread fracture were analyzed by combining the theory with experiment, and the casing safe service window with harsh working conditions was given. The operation of the failed casing and determined the actual working conditions of the casing threaded joints during the running process were investigated in this paper. According to the theoretical method, the boundary conditions and load conditions of the fracture casing joint in service were determined. With the aid of full-scale physical simulation test device, as well as the above boundary conditions and load conditions, the same batch casing tensile bearing characteristics were determined. Through nondestructive testing, the metallographic observation, scanning electron microscopy, spectral analysis and up-and-down test, the main controlling factors of casing thread fracture were determined. By the finite element analysis, the casing threads service state under axial tension and bending loads was established, the safety performance of threads under ideal working conditions was studied, and the fatigue mechanism of threads was revealed. Combined with the analysis results, the corresponding relationship between the casing tensile bearing characteristics and safety factor was given, which provides technical support for the safe service selection of casing body and thread under harsh conditions, saving cost and shortening the well construction period.

Article Highlights By low-temperature aging, superior bromine-free FA1–xMAxPbI3 perovskite film is realized.By suppressing lead iodide on the surface of perovskite, no further passivation step or layer is needed. The efficiency of planar perovskite solar cells is improved to 22.41% with robust reproducibility. Electronic supplementary material The online version of this article (10.1007/s40820-020-00418-0) contains supplementary material, which is available to authorized users., Previous reports of formamidinium/methylamine (FAMA)-mixed halide perovskite solar cells have focused mainly on controlling the morphology of the perovskite film and its interface—for example, through the inclusion of bromine and surface passivation. In this paper, we describe a new processing pathway for the growth of a high-quality bromine-free FAMAPbI3 halide perovskites via the control of intermediate phase. Through low-temperature aging growth (LTAG) of a freshly deposited perovskite film, α-phase perovskites can be seeded in the intermediate phase and, at the same time, prevent beta-phase perovskite to nucleate. After postannealing, large grain-size perovskites with significantly reduced PbI2 presence on the surface can be obtained, thereby eliminating the need of additional surface passivation step. Our pristine LTAG-treated solar cells could provide PCEs of greater than 22% without elaborate use of bromine or an additional passivation layer. More importantly, when using this LTAG process, the growth of the pure alpha-phase FAMAPbI3 was highly reproducible. Electronic supplementary material The online version of this article (10.1007/s40820-020-00418-0) contains supplementary material, which is available to authorized users.

Blue-emitting perovskites can be easily attained by precisely tuning the halide ratio of mixed halide (Br/Cl) perovskites (MHPs). However, the adjustable halide ratio hinders the passivation of Cl ...

An acceptor-donor-acceptor (A-D-A)-type non-fullerene acceptor (NFA), PTTtID-Cl, featuring thieno[3,2-b]thieno[2''',3''':4'',5'']-pyrrolo[2'',3'':4',5']thieno[2',3':4,5]thieno-[2,3-d]pyrrole (DTPTt) as the electron-rich core and 2-(5,6-dichloro-3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile (ID-Cl) as the peripheral electron-deficient terminal group was synthesized and characterized. PTTtID-Cl exhibited strong absorption in the range of 700-850 nm in CHCl3 and redshifted absorption centered at 881 nm in a thin film. The near infrared (NIR)-absorption of PTTtID-Cl was combined with a low-bandgap polymer donor (PTB7-Th) to achieve binary and semitransparent organic photovoltaics (OPVs) with a power conversion efficiency (PCE) of 8.9 % and 7.7 % (with an average visible transmittance (AVT) of 16.7 %), respectively. A ternary device with a ratio of PM7/PTTtID-Cl/IT-4F=1:0.15:0.85 (w/w) achieved a short-circuit current density of 19.46 mA cm-2 , an open-circuit voltage of 0.87 V, and a fill factor of 71.2 %, giving a PCE of 12.0 %. In addition, by employing the Ag/ITO/Ag microcavity structure, semitransparent colorful binary organic photovoltaics (OPVs) with superior transparency of 27.9 % at 427 nm and 22.7 % at 536 nm for blue and green devices, respectively, were prepared. The semitransparent colorful devices based on the optimized ternary blend gave PCEs of 8.7 %, 8.4 %, and 9.1 % for blue, green, and red devices, respectively. These results indicate the promising potential of PTTtID-Cl as a NIR-absorption NFA for applications in semitransparent colorful binary and ternary OPVs.

To meet the needs of corrosion resistance and electrically conductivity for metallic bipolar plates that are employed in proton exchange membrane fuel cells (PEMFCs), a TiSiN nanocomposite coating was fabricated on to a Ti–6Al–4V substrate using reactive sputter-deposition through the double cathode glow discharge plasma technique. The microstructure of the TiSiN coating comprised nanocrystallite TiN grains embedded in an amorphous Si3N4 matrix. Electrochemical measurements were employed to investigate the corrosion behavior of the TiSiN coating in the simulated operating environments of a PEMFC, specifically 0.5 M H2SO4 solution containing different HF concentrations (namely 2, 4 and 6 ppm) at 70 °C pumped with H2 at the anode and air at the cathode. With increasing HF concentration, a higher corrosion current density and lower corrosion potential were observed from both the coating and the uncoated substrate, indicating that the addition of HF accelerated their corrosion rates under these conditions. Compared to the uncoated substrate, the TiSiN coating showed a markedly higher corrosion resistance at all HF concentrations. The passive film that formed on the TiSiN coating, with a resistance of the order of magnitude of ~107 Ω cm2, displayed good electrochemical stability and was less affected by changes in HF concentration. For the TiSiN coating, the values of interfacial contact resistance (ICR) were 14.7 mΩ cm−2 and 18.3 mΩ cm−2, respectively, before and after 2.5 h potentiostatic polarization with 6 ppm HF under cathodic conditions under a compaction pressure of 140 N cm−2. Both values are much lower than those for the bare substrate. Moreover, the TiSiN coating was shown to improve the hydrophobicity of Ti–6Al–4V that would help facilitate water management in the PEMFC operating environment. This coating, which exhibited excellent corrosion resistance, electro-conductivity and hydrophobicity, is therefore a promising material for protecting metallic bipolar plates from corrosive attack.

Light-emitting diodes (LEDs) based on excitonic material systems, in which tightly bound photoexcited electron–hole pairs migrate together rather than as individual charge carriers, offer an attractive route to developing solution-processed, high-performance light emitters. Here, we demonstrate bright, efficient, excitonic infrared LEDs through the incorporation of quantum dots (QDs)1 into a low-dimensional perovskite matrix. We program the surface of the QDs to trigger fast perovskite nucleation to achieve homogeneous incorporation of QDs into the matrix without detrimental QD aggregation, as verified by in situ grazing incidence wide-angle X-ray spectroscopy. We tailor the distribution of the perovskites to drive balanced ultrafast excitonic energy transfer to the QDs. The resulting LEDs operate in the short-wavelength infrared region, an important regime for imaging and sensing applications, and exhibit a high external quantum efficiency of 8.1% at 980 nm at a radiance of up to 7.4 W Sr−1 m−2. Embedding perovskite quantum dots in perovskite leads to bright, efficient 980 nm LEDs with applications in imaging and sensing.

We acknowledge the use of KAUST Core Lab and KAUST Solar Center facilities. This work was supported by KAUST and the Office of Sponsored Research (OSR) under award no. OSR-2017-CRG-3380. F.G. is a Wallenberg Academy Fellow.

Influence of hydrogen concentration and defects introduced by neutron irradiation on hydrogen diffusion in tungsten has been investigated by molecular dynamics simulation at elevated temperatures. Hydrogen diffusion is shown to be significantly restrained at high concentrations due to spontaneous formation of platelet-like hydrogen clusters. For neutron irradiation defects, self-interstitials, mono-vacancies and vacancy clusters are considered. By clustering and acting as dislocation loops, self-interstitials show considerable trapping effects on hydrogen, leading to the suppression of hydrogen effective diffusion and the change of diffusion model in which hydrogen mainly diffuses along dislocation lines instead of hopping between tetrahedral interstitial sites. Moreover, an equation connecting hydrogen diffusion parameters and the total length of dislocation loops is empirically established. Different influences of mono-vacancies and vacancy clusters on hydrogen diffusion have been carefully identified. With the same vacancy concentration, hydrogen diffusivity is lower with mono-vacancies than that with vacancy clusters because more isolated trapping sites are provided by mono-vacancies. This work is not only helpful for understanding the synergistic effects of neutron irradiation and plasma interaction, but also potentially applicable for larger scale simulations as input data.

The n-type hexagonal (Bi(Bi2S3)9)I3)0.667 compound was synthesized by a facile process, a hydrothermal method combined with spark plasma sintering. The thermoelectric properties of the (Bi(Bi2S3)9)I3)0.667 bulk sample were investigated in detail. The results show that a peak ZT value of 0.04 was obtained at 673 K along the perpendicular pressure direction.

Deep-blue light-emitting diodes (LEDs) (emitting at wavelengths of less than 450 nm) are important for solid-state lighting, vivid displays and high-density information storage. Colloidal quantum dots, typically based on heavy metals such as cadmium and lead, are promising candidates for deep-blue LEDs, but these have so far had external quantum efficiencies lower than 1.7%. Here we present deep-blue light-emitting materials and devices based on carbon dots. The carbon dots produce emission with a narrow full-width at half-maximum (about 35 nm) with high photoluminescence quantum yield (70% ± 10%) and a colour coordinate (0.15, 0.05) closely approaching the standard colour Rec. 2020 (0.131, 0.046) specification. Structural and optical characterization, together with computational studies, reveal that amine-based passivation accounts for the efficient and high-colour-purity emission. Deep-blue LEDs based on these carbon dots display high performance with a maximum luminance of 5,240 cd m−2 and an external quantum efficiency of 4%, notably exceeding that of previously reported quantum-tuned solution-processed deep-blue LEDs. Deep-blue high-colour-purity light-emitting materials are developed by using amine-based edge passivation. The light-emitting diodes based on the carbon dots exhibit a maximum luminance of 5,240 cd m–2 and an external quantum efficiency of 4%.

Mechanical responses of tungsten (W) and its alloys are strongly controlled by the properties of 1/2 screw dislocations. Rhenium (Re), as a typical alloying and transmutation element in W, can substantially modify the properties of the dislocations, thus the plasticity of the materials. In this study, we investigate the interaction of Re and Re clusters with the screw dislocations in W by first-principles calculations in combination with theoretical models. Specifically, we propose two competing and Re-distribution dependent mechanisms, i.e. “ductilizing effect” and “hardening effect”; both are crucial to the mechanical properties of W. For the ductilizing effect, dispersed Re atoms weaken the surrounding interatomic interaction and reduce the shear resistance, thus facilitating the motion of the dislocation. In contrast, for the hardening effect, Re clusters formed by aggregated Re atoms due to irradiation can increase the Peierls stress and energy, thus hindering the motion of the dislocations. The proposed mechanisms shed light on the experimental observations that there is a Re-induced transition from ductilizing to hardening due to irradiation. The current work provides a theoretical guidance to the development of W-based future fusion materials in search of ductilizing alloying elements.

The primary lining structure plays a key role in blasting tunnel construction, and its intensity change and dynamic response directly affect the security of tunnel structures. To investigate the dynamic response of the primary lining structure under blasting loads, combing field test with numerical simulation was conducted in the new passenger line railway that traverses from Beijing to the Shenyang TJ-1 (Liaoning) Sanlengshan tunnel. The peak particle vibration velocity data were recorded by conducting eight monitoring tests at three measuring points by using TC-4850. The Sadaovsk formula for the propagation law of peak particle vibration velocity was fitted by using the least squares method. The numerical simulation software LS-DYNA was used to obtain material and equation parameter based on, and the reliability of the numerical model was verified by using the propagation law of peak particle vibration velocity to determine the variations in the stress and displacements in key locations (i.e., skew, haunch, spandrel, and vault) while considering the strength of the primary lining. Results show that the maximum stress of the tunnel primary lining structure at the skew and vault in the X direction is greater than at the haunch and spandrel. The maximum stress values in the Y and Z directions are 0.1 181 MPa and 0.239 1 MPa at the skew, respectively. The maximum stress value in the Z direction is larger than that in the X and Y directions. The maximum displacement value of the tunnel primary lining structure is 3.61 mm at the haunch and appears in the Z direction much earlier than in the X and Y directions. By increasing the primary lining strength of C25 and C35, the stress becomes positive, whereas the displacement shows a negative relationship.

By performing the first-principles calculations, we explore the dissolution and diffusion of hydrogen (H) in hexagonal closed packed zirconium (Zr) as well as its interaction with vacancy. We show that the tetrahedral (TE) interstitial site is the favorable trapping site for a single H atom with the solution energy of −0.45 eV. Such a negative solution energy is due to the strong electronic bond between H and neighboring Zr atoms. Moreover, the energy barrier for the migration of H from a TE site to its 1NN and 2NN TE site is 0.12 eV and 0.42 eV, respectively. It is noteworthy that the first path only slightly contributes to the experimentally measured H diffusivity in Zr, because the H atom is trapped by two nearest neighboring TE sites. Thus, the effective activation energy for H diffusion in Zr should be mainly determined by the second path, and the corresponding energy barrier is 0.42 eV. Furthermore, since the electronic density (available volume) in vacancy is lower (larger) than that of interstitial site, vacancy is a strong trap for H atoms in Zr. We demonstrate that the maximum of 8 H atoms can be accommodated in a mono-vacancy without the observation of H2 molecule. These results can provide a basis to develop Zr materials in nuclear cladding devices.

High-energy collision cascades with an energy of up to 300 keV for the primary knock-on atom (PKA) have been initially simulated in W and W–Re alloys containing 5 or 10 at.% Re atoms using the molecular dynamics method with recently fitted W–Re interatomic potentials. The effects of PKA energy and Re concentration on defect production, defect clustering and states of dislocation loops have been quantitatively analysed. The results show that the presence of Re atoms does not significantly affect either the number of surviving defects or their clustered fractions. In addition, the interstitial dislocation loops are dominated by the 1/2 loops. Mixed interstitial loops with 1/2 and Burgers vectors and interstitial loops that have the same Burgers vectors but are located on different habit planes have also been observed. Further analysis indicates that the pinning effect induced by the Re atom segregation leads to the lower mobility of the interstitial clusters and interstitial 1/2 loops in W–Re alloys than in pure W, which is expected to influence the subsequent evolution of radiation-induced defects in W–Re alloy.

Compressive Sensing for Magnetic Resonance Imaging (CS-MRI) aims to reconstruct Magnetic Resonance (MR) images from under-sampled raw data. There are two challenges to improve CS-MRI methods, i.e. designing an under-sampling algorithm to achieve optimal sampling, as well as designing fast and small deep neural networks to obtain reconstructed MR images with superior quality. To improve the reconstruction quality of MR images, we propose a novel deep convolutional neural network architecture for CS-MRI named MRCSNet. The MRCSNet consists of three sub-networks, a compressive sensing sampling sub-network, an initial reconstruction sub-network, and a refined reconstruction sub-network. Experimental results demonstrate that MRCSNet generates high-quality reconstructed MR images at various under-sampling ratios, and also meets the requirements of real-time CS-MRI applications. Compared to state-of-the-art CS-MRI approaches, MRCSNet offers a significant improvement in reconstruction accuracies, such as Peak Signal-to-Noise Ratio (PSNR) and Structural Similarity (SSIM). Besides, it reduces the reconstruction error evaluated by the Normalized Root-Mean-Square Error (NRMSE). The source codes are available at https://github.com/TaihuLight/MRCSNet .

Three different complexes, TMeQ[6]-TBT, Q[7]-TBT and Q[8]-TBT, are constructed by three different cucurbiturils and synthesized guest melamine-cored Schiff base (TBT) through outer-surface interaction and host-guest interaction, where TBT and TMeQ[6] form complex TMeQ[6]-TBT through outer-surface interaction, while TBT and Q[7,8] form complexs Q[7]-TBT and Q[8]-TBT through host-guest interaction., and finally, Q[7]-TBT is selected as a UV detector for the detection of precious metal Ag+. This work makes full use of the characteristics of each cucurbiturils and combines that of Schiff bases to construct a series of complexes and apply them to metal detection.

Atomic valence state regulation is an advantageous approach for improving photocatalytic efficiency and product selectivity. However, it is difficult to precisely control the ratio of the different valence states on the surface and the relationship between the surface valence change and catalytic efficiency in the photocatalytic reaction process is unclear. Herein, CeVO4 ultrathin nanosheets were fabricated by one-step solvothermal method with ethanolamine (MEA) as the structure-directing agent. The ratio of the concentrations of intrinsic Ce4+ and Ce3+ ions is precisely modulated from 19.82:100 to 13.33:100 changed by the volume of MEA added without morphology modification. The photocatalytic efficiency increases as the concentrations of intrinsic Ce4+ and Ce3+ ions decrease and CV3 (prepared with 3 mL of MEA) shows the highest CO generation rate approximately 6 and 14 times larger than CV (prepared without MEA) and CV1 (prepared with 1 mL of MEA), respectively, in the photocatalytic CO2 reduction. Interestingly, about 6.8% photo-induced Ce4+ ions were generated on the surface of the catalysts during the photocatalytic CO2 reduction without any phase and morphology changes for CV3. The photocatalytic reaction mechanism is proposed considering the intrinsic and photo-induced Ce4+ ions to obtain efficient photocatalysts.

Perovskite light‐emitting diodes (PeLEDs) have attracted tremendous research interest in recent years. Cesium lead bromide's (CsPbBr3) high color purity, intrinsically high photoluminescence quantum yield, and tunable emission wavelength make it a strong candidate as an emitter for light‐emitting applications. Organic charge transport materials and their impact on the growth mode of the perovskite layer have a pivotal influence on the device performance. Herein, it is reported that hole transport layers (HTLs) with higher glass transition temperatures (Tg) are critical to facilitate the growth of crystalline perovskites and thus the color purity. Second phase regions with higher Pb density are observed in films growing on HTLs with inadequate lower Tg. A minimum 100 °C glass transition is found to be essential to grow cesium lead bromides with sharp emission peaks. In addition to high glass transition temperature, high ionization energy (>5.6 eV) is also found to be important to remove the HTL/perovskite injection barrier. The optimal device in this study is fabricated with 3,5‐di(9H‐carbazol‐9‐yl)tetraphenylsilane (SimCP2) as the HTL and the device shows a very sharp 19 nm full‐width at half‐maximum emission.

Bi2S3, with earth-abundant compositions and a low thermal conductivity, is regarded as a candidate thermoelectric material. In this work, Bi2S3 samples that were doped with x % mol InCl3 were successfully fabricated via a mechanical alloying and spark plasma sintering process. InCl3, as an n-type donor dopant, was added to the Bi2S3 system to improve its electrical transport properties and optimize its thermal conductivity. Upon doping, the electrical conductivity of Bi2S3 doped with 1 mol% InCl3 reaches up to 62 Scm−1, and the Seebeck coefficient maintains a relatively large value of −244 μV K−1 at 673 K, which results in a maximum power factor of 363 μW m−1 K−2. Furthermore, due to a simultaneously reduced thermal conductivity at high temperature, a ZT peak of 0.57 is obtained at 673 K along the parallel to the press direction for the sample doped with 1.0 mol% InCl3, which is almost four times higher than that of pristine Bi2S3 (0.14 at 673 K). The elastic properties and Debye temperature of Bi2S3 are also calculated to analyze the origin of the intrinsically low thermal conductivity and are compared to those of other thermoelectric materials with a low thermal conductivity.

We have investigated the dissolution, diffusion, and retention of hydrogen (H) in tungsten-rhenium (W-Re) sigma (σ) phase using a first-principles method and thermodynamic models, in order to explore the influence of Re-rich precipitation on H behaviors in W. Taking the most stable W-Re σ phase (W-33.3 at.% Re) as an example, it is found that the solution energy of H at most interstitial sites (>80%) in W-Re σ phase is much lower than that in pure W. Specifically, the H solution energy at most stable interstitial site in W-Re σ phase is only 0.47 eV, ~54% lower than that in pure W. This can be attributed to that W-Re σ phase provides the larger available volume for interstitial H than the pure W, weakening the W-H repulsive interaction. Moreover, it has been demonstrated that this trend is almost independent on the Re concentration in W-Re σ phase. We have further determined the interaction between H atoms and mono-vacancy in W-Re σ phase based on the calculation of H trapping energies and the Polanyi-Wigner equation. The W-type and Re-type vacancy can accommodate 10 and 5 H atoms at room temperature (RT) in σ phase, respectively, and thus the average trapping capability of vacancy for H in σ phase is stronger than that in pure W (~6 H atoms at RT). Consequently, our calculations reveal that the Re-rich precipitation (both interstitial and vacancy sites) can serve as the strong trapping centers for H in W, significantly enhancing the H retention, which is entirely different from the negative effect of dispersed-Re/small Re clusters.

Considering the rough surface as a fractal model makes the research of contact parameters more practical. In the fractal model of the machined surface, the parameters describing the surface topography are independent of the measurement resolution. Based on the elastic, elasto-plastic and plastic deformations of a single pair of contact asperities, a normal contact stiffness model using the fractal model for surface topography description is proposed in this paper. The specimens machined by milling and grinding methods are used to verify the proposed contact stiffness model based on the fractal theory. The experimental and theoretical results indicate that the proposed contact stiffness model is appropriate for the machined joint surfaces.

Tungsten and tungsten-tantalum alloy with tantalum concentration of 10 wt%, sintered by spark plasma sintering, were exposed to deuterium plasma at ∼500 K with flux of 1 × 1021–1 × 1022 D m−2s−1, an ion energy of 40 eV and fluence of 1 × 1025–1 × 1026 D m−2. After exposure, a large number of blisters with an average size of 1–2 μm form on the surface of tungsten, and the area density of blisters increases with increasing irradiation fluence. However, the dominant morphology on the surface of tungsten-tantalum alloy is characterized by the striped microstructure, and exhibits a strong grain-orientation dependence. TDS results show two major desorption peaks located at ∼650 K and ∼770 K for tungsten and tungsten-tantalum alloy, respectively. Furthermore, the deuterium retention in tungsten is 4–6 times more than that in the tungsten-tantalum alloy. It is suggested that tantalum alloying can be expected to suppress the surface blistering and reduce the deuterium retention in tungsten.

Tungsten (W) and W-based alloys are the leading candidates for plasma-facing materials (PFMs) in future fusion reactors. However, the high energy neutrons generated in fusion reactions not only result in cascade damages but also cause W transmutation. Both the irradiation defects and transmutation products, mainly rhenium (Re), have serious effects on the service behaviors of W PFMs. In this work, we have systematically investigated the interaction between Re and the self-interstitial atoms, self-interstitial clusters and 1/2 interstitial dislocation loops in bulk W using molecular dynamics and statics simulations. It is found that there is a strong attractive interaction between an interstitial W atom and a substitutional Re atom, forming a Re–W dumbbell that migrates 3-dimentionally due to the low migration and rotation energies. The small SIA clusters strongly bind with both the substitutional Re atoms and an interstitial Re atom (Re–W mixed dumbbell), thus decreasing the mobility of these clusters. The strong attractive interaction between a Re atom and a 1/2 interstitial dislocation loop occurs when the Re atom is located at the core of the loop, and also, their interaction distance along direction is large. The mobility of the 1/2 interstitial dislocation loop decreases progressively with increasing Re concentration.

Surface morphology and deuterium retention in tungsten have been examined after exposure to a low-energy deuterium plasma with an ion fluence of 6.0 × 1024 D/m2 at various temperatures. Optical differential interference contrast microscope and scanning electron microscope equipped with focused ion beam were applied for surface observations. D (3He, p) 4He nuclear reaction at 3He energies varying from 0.5 to 4.5 MeV was used to determine the deuterium depth distributions within the depth of 8.0 μm. The thermal desorption spectroscopy was applied for deuterium retention measurement. The observed surface blistering and deuterium retention are found to strongly depend on the exposure temperature. At 230 K, many small blisters are formed on the tungsten surface. As the exposure temperature increases to 370 K, the blisters become sparser and larger. At 520 K no blisters appear. The deuterium retention is 1.4 × 1020 D/m2 at 230 K. Then it increases to 1.1 × 1021 D/m2 as the exposure temperature rises to 370 K, and decreases to 2.3 × 1020 D/m2 at 520 K.

Here, we review recent computational findings focused on the behavior of transmutation elements (TEs) in Tungsten (W). W is chosen as one of the most promising materials for the divertor armor and plasma facing components in future fusion reactors. However, W in exposure of fusion neutrons can cause the transmutation reaction and produce TEs, such as rhenium and osmium. The presence of TEs can change chemical component of materials, and therefore inevitably influence the microstructure and properties of W materials. Multiscale simulation methods have been employed to investigate the dissolution, diffusion and radiation induced precipitation of TEs, as well as their effects on the behaviors of hydrogen isotopes in W. This systematic review can provide an insightful understanding to estimate the influence of TEs on the properties and performance of W-based materials. Keywords: Tungsten, Transmutation elements, Radiation induced precipitation, Point defects, Hydrogen

Organic light-emitting diodes (OLEDs) are attractive for display and lighting applications. However, the demand for high stability in outdoor display and lighting requires further material and device developments and theoretical modeling. Here an analytical function for predicting time-dependent luminance loss in OLEDs is derived based on excitonic defect generation and interaction. Despite the simplicity, this function fits extremely well vast amount of experimental data reported by numerous industrial and academic laboratories for a variety of devices including simple bilayer devices and multilayered devices using singlet, triplet, multiple emitters in variety of host:dopant combinations. The uniqueness of the derived function is expected to allow it to be broadly used for understanding root-cause in degrading devices and for modeling OLED lifetime.

Precise real-time detection of Terahertz pulses is a key requirement in Terahertz communication technology, non-destructive testing, and characterization of pulsed Terahertz sources. We experimentally evaluate the speed limits of Terahertz rectification in field-effect transistors using the example of pulses from a free-electron laser. We develop an improved model for the description of these Terahertz pulses and demonstrate its validity experimentally by comparison to spectroscopic data as well as to expectation values calculated from free-electron laser physics. The model in conjunction with the high speed of the detectors permits the detection of an exponential rise time of the pulses as short as 5 ps despite a post detection time constant of 11 and 14 ps for a large area and an antenna-coupled detector, respectively. This proves that field-effect transistors are excellent compact, roomtemperature Terahertz detectors for applications requiring an intermediate frequency bandwidth of several tens of GHz.

This contribution summarized the recent studies of tungsten-based plasma-facing materials in the linear plasma device like the simulator for tokamak edge plasma (STEP), focusing on the examination of newly developed tungsten (W)-based materials and plasma-induced defects in pure W. Pure W, W-V, W-Y2O3 and W-ZrC samples were exposed to a high-flux plasma of ~ 1021–1022 m−2 s−1 with a fluence up to 1026 m−2 at a surface temperature below 500 K. The investigation of fundamental evolution of plasma-induced defects in pure W indicated a critical role of hydrogen-dislocation interactions. Suppressed surface blistering was observed in all W-based materials, but deuterium desorption behavior and retention were distinct with respect to different materials. The studies showed that the linear plasma device like the STEP was indispensable in the understanding of plasma-material interactions and the qualification of new materials for future fusion reactors.

We investigate the effects of the hydrostatic strain on the dissolution, diffusion, and clustering of alloying/transmutation elements rhenium (Re) and osmium (Os) in tungsten (W) by using the first-principles method in combination with thermodynamic models. Results show that the strain has significant influences on the dissolution/diffusion of Re/Os as well as their interactions with defects, and thus enhances the clustering of Re/Os in W. For defect-free case, the tensile strain can enhance the clustering of Re/Os in W, while the compressive one can inhibit the formation of Re/Os clusters. Specifically, the energy barrier of Os nucleation in W under 5% tensile (compressive) strain is 0.52 eV (2.32 eV), which is 66% lower (53% higher) than that in strain-free W, suggesting that the tensile/compressive strain has a prominent effect on the clustering of Os in W. Further, the tensile strain can improve the stability of multi Re/Os complexes with SIA and reduce the vacancy-mediated diffusion energy barrier of Re/Os, indicating that the tensile strain can also facilitate the clustering of Re/Os in W with defects. Based on our calculated results, we thus propose a strain-triggered cascading effect of Re/Os clustering in W, i.e., the dissolution and accumulation of Re/Os induce a tensile strain in W lattice surrounding the Re/Os atoms, which in turn further facilitates the clustering of Re/Os in W.

An aqueous blend of 1-butyl-3-methylimidazolium tetrafluoroburate ([Bmim][BF4]) + piperazine (PZ) was proposed in this work. Density and viscosity of the aqueous blend were measured and correlated at (293.15–333.15) K and atmospheric pressure. Performance of CO2 absorption into the aqueous blend was evaluated. It turned out that PZ mass fraction slightly influenced on the density and viscosity, being linear with them. Temperature significantly affected the viscosity. The calculated values are in good agreement with the experimental values. The main factors affecting the CO2 loading of the aqueous blend were PZ mass fraction, gas CO2 mole fraction and temperature. The average absorption rate of the aqueous blend was the biggest in the aqueous [Bmim][BF4], PZ and [Bmim][BF4]/PZ, and much higher than that of the former two. The performance of the aqueous [Bmim][BF4]/PZ with low PZ mass fraction was better than that with high PZ mass fraction. It demonstrated that the aqueous blend of [Bmim][BF4]/PZ is a good absorbent of CO2.

The elastic prestressed ultrasonic peen forming (UPF) was adopted in order to solve problems of insufficient bending deformation and large spherical deformation of plate during free UPF. The theoretical analysis of prestressed UPF and the influence of elastic prebending moment on deformation were analyzed. Spherical deformation coefficient was defined to quantificationally describe the spherical deformation. Experiments were conducted to compare the differences between free UPF and prestressed UPF processes and the effects of processing parameters on bending curvature and spherical deformation coefficient were studied. The results show that peening trajectory in chordwise direction is beneficial to enlarging spanwise bending deformation and decreasing spherical deformation coefficient. Large prebending curvature is helpful to increase spanwise bending deformation and decrease chordwise deformation, thereby obviously decreasing spherical deformation coefficient. Large spanwise deformation can be obtained under large firing pin velocity, small plate thickness and small offset distance. Large firing pin velocity plays a positive role in decreasing spherical deformation, while plate thickness and offset distance have little effect on it. Above all, prebending curvature and peening trajectory are the most important factors during prestressed UPF process. This study provides guidance for parameters optimization of prestressed UPF for wing plate with large thickness.