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Proton exchange membrane water electrolysis (PEMWE) is a promising technology for sustainable hydrogen production. However, the anodic oxygen evolution reaction (OER) is a critical bottleneck restricting the power-to-gas efficiency and the widespread application of PEMWE devices because the harsh acidic and oxidative environment causes drastic catalyst structural evolution and thus severe catalyst dissolution/corrosion as well as performance degradation. Currently, the lack of deep insight for identifying the real catalytic sites during the structural evolution and the distinctions of reaction mechanisms have hindered the development of highly active and durable OER catalysts for PEMWE. Therefore, elucidating the OER-induced structure evolution and understanding the underlying mechanisms are recognized as the foundations for PEMWE technology. Against this backdrop, in situspectroscopic characterization techniques serve as powerful tools for achieving this goal by enabling the real-time monitoring of the catalytic structure and the capture of key intermediates. This Account summarizes the recent advances in cutting-edge in situspectroscopy techniques for probing the acidic OER process. The fundamentals and device configurations of these techniques are briefly introduced, and the advantages of each technique for monitoring the catalyst structural evolution and identifying the intermediates to unveil the underlying mechanisms have also been discussed. Finally, the challenges, development trends, and prospects in this field are presented.

The aggregation behavior and solid-state microstructures of conjugated polymers play an important role in optoelectronic properties and device performances. Adaption of classical polymer theory and phenomenological discussion of the structure were commonly applied to unravel the nature of aggregation. However, the broadened molecular weight distribution and the discrepancy in interactions between polymer backbones and alkyl chains increase the difficulty in pinpointing the nature of the aggregation mechanism and behavior. Here, four conjugated polymers were developed to construct the relationship between the polymer conformation and the aggregation behavior. The effect of the interunit torsion and the flexibility differences of the conjugated chains on the aggregation behaviors in solutions was investigated in detail. On this basis, a model combined with supramolecular polymerization and classical polymer theory brought a new perspective of thermodynamics to unravel the aggregation process in solution. The aggregation equilibrium inclined toward short-range/long-range π-stacks with planar/torsional units, and the disaggregated species inclined toward dispersed chains/coils with a rigid/flexible backbone. Furthermore, the aggregation structures were inherited to the solid phase, resulting in excellent electronic properties for the planar and rigid polymers and strong domain-regulation ability for the torsional and flexible polymers. Our investigation pioneers the introduction of supramolecular aggregation theory into the study of the aggregation behavior of conjugated polymers in solution, which sheds light on the nature of the aggregation of conjugated polymers from a thermodynamic perspective, constructs a landscape for the aggregation process, and also provides guidance for the structure design and the selection of modulation methods matching the structure and performance requirements.

Interfacing organic molecular groups with well-defined inorganic lattices, especially in low dimensions, enables synthetic routes for the rational manipulation of both their local or extended lattice structures and physical properties. While appreciably studied in two-dimensional systems, the influence of surface organic substituents on many known and emergent one-dimensional (1D) and quasi-1D (q-1D) crystals has remained underexplored. Herein, we demonstrate the surface functionalization of bulk and nanoscale Chevrel-like q-1D ionic crystals using In2Mo6Te6, a predicted q-1D Dirac semimetal, as the model phase. Using a series of alkyl ammonium (−NR4+; R = H, methyl, ethyl, butyl, and octyl) substituents with varying chain lengths, we demonstrate the systematic expansion of the intrachain c-axis direction and the contraction of the interchain a/b-axis direction with longer chain substituents. Additionally, we demonstrate the systematic expansion of the intrachain c-axis direction and the contraction of the interchain a/b-axis direction as the alkyl chain substituents become longer using a combination of powder X-ray diffraction and Raman experiments. Beyond the structural modulation that the substituted groups can impose on the lattice, we also found that the substitution of ammonium-based groups on the surface of the nanocrystals resulted in selective suspension in aqueous (NH4+-functionalized) or organic solvents (NOc4+-functionalized), imparted fluorescent character (Rhodamine B-functionalized), and modulated the electrical conductivity of the nanocrystal ensemble. Altogether, our results underscore the potential of organic–inorganic interfacing strategies to tune the structural and physical properties of rediscovered Chevrel-type q-1D ionic solids and open opportunities for the development of surface-addressable building blocks for hybrid electronic and optoelectronic devices at the nanoscale.

The realization of stable monolayers from 2D van der Waals (vdW) solids has fueled the search for exfoliable crystals with even lower dimensionalities. To this end, 1D and quasi-1D (q-1D) vdW crystals comprising weakly bound subnanometer-thick chains have been discovered and demonstrated to exhibit nascent physics in the bulk. Although established micromechanical and liquid-phase exfoliation methods have been applied to access single isolated chains from bulk crystals, interchain vdW interactions with nonequivalent strengths have greatly hindered the ability to achieve uniform single isolated chains. Here, we report that encapsulation of the model q-1D vdW crystal, Sb2Se3, within single-walled carbon nanotubes (CNTs) circumvents the relatively stronger c-axis vdW interactions between the chains and allows for the isolation of single chains with structural integrity. High-resolution transmission electron microscopy and selected area electron diffraction studies of the Sb2Se3@CNT heterostructure revealed that the structure of the [Sb4Se6]nchain is preserved, enabling us to systematically probe the size-dependent properties of Sb2Se3from the bulk down to a single chain. We show that ensembles of the [Sb4Se6]nchains within CNTs display Raman confinement effects and an emergent band-like absorption onset around 600 nm, suggesting a strong blue shift of the near-infrared band gap of Sb2Se3into the visible range upon encapsulation. First-principles density functional theory calculations further provided qualitative insight into the structures and interactions that could manifest in the Sb2Se3@CNT heterostructure. Spatial visualization of the calculated electron density difference map of the heterostructure indicated a minimal degree of electron donation from the host CNT to the guest [Sb4Se6]nchain. Altogether, this model system demonstrates that 1D and q-1D vdW crystals with strongly anisotropic vdW interactions can be precisely studied by encapsulation within CNTs with suitable diameters, thereby opening opportunities in understanding dimension-dependent properties of a plethora of emergent vdW solids at or approaching the subnanometer regime.

Sensor networks play an important role in structural health monitoring and tactile sensors. General sensor networks require different types and a large number of sensors. This article proposes a shape memory alloy (SMA) sensor interwoven network. Without the need for additional force or displacement sensors, the position of one external force acting on the sensor network can be estimated, and the magnitude of the force and the corresponding deformation of the sensor network can be determined, only by measuring the resistance of the SMA wires. This article not only proposes a theoretical analytical model to solve the force position and its magnitude, and even the entire deformation of the SMA sensor network, but also designs a sensor network and its test bench for loading experiments. The experimental results confirm the feasibility of the theoretical model. The SMA sensor interwoven network has important application value under the condition that it is not convenient to directly observe the position of the external force and monitor the force size, such as an intelligent self-sensing badminton racket at least.

Sidechain engineering as an efficient and convenient strategy has been widely used to optimize molecular structure of photovoltaic materials for boosting power conversion efficiency (PCE) of organic solar cells (OSCs). Herein, a new Y-series acceptor named Y-ThSi with trialkylsilyl-substituted thiophene as conjugated sidechain is developed. Compared with its parental Y6 with multiple intermolecular interactions, Y-ThSi has a unitary molecular packing due to the additional steric hindrance from two-dimensional (2D)-conjugated trialkylsilyl-thiophene. Therefore, Y-ThSi shows an obviously blue-shifted absorption with an onset of ~850 nm but significantly up-shifted lowest unoccupied molecular orbital energy level. For the PM6:Y-ThSi pair, the spin-coating OSCs achieve a decent PCE of 14.56% with an impressively high photovoltage (VOC) of 0.936 V. Inspired by its high VOCand narrow absorption, Y-ThSi is introduced into near-infrared absorbing binary PM6:BTP-eC9 host to construct ternary OSCs. Thanks to the complementary absorption, optimized morphology, and minimized energy loss properties, the PM6: BTP-eC9:Y-ThSi-based OSCs offer a higher PCE of 18.34%. Moreover, our developed strategy can overcome the commonly existed PCE drop when the blade-coating towards large-scale printing is used instead. Therefore, a comparable PCE of 18.34% is achieved, which is one of the best values for the blade-coating OSCs so far.

Digital immunoassays with multiplexed capacity, ultrahigh sensitivity, and broad affordability are urgently required in clinical diagnosis, food safety, and environmental monitoring. In this work, a multidimensional digital immunoassay has been developed through microparticle-based encoding and artificial intelligence-based decoding, enabling multiplexed detection with high sensitivity and convenient operation. The information encoded in the features of microspheres, including their size, number, and color, allows for the simultaneous identification and accurate quantification of multiple targets. Computer vision-based artificial intelligence can analyze the microscopy images for information decoding and output identification results visually. Moreover, the optical microscopy imaging can be well integrated with the microfluidic platform, allowing for encoding-decoding through the computer vision-based artificial intelligence. This microfluidic digital immunoassay can simultaneously analyze multiple inflammatory markers and antibiotics within 30 min with high sensitivity and a broad detection range from pg/mL to μg/mL, which holds great promise as an intelligent bioassay for next-generation multiplexed biosensing.

Precision control via molecular structure over adaptive conjugated polymer properties in aqueous environments is critical for realizing their biomedical applications. Here, we unravel the dependence of amphiphilic peptide-polydiacetylene (PDA) conjugate properties on the characteristic steric and hydrophobic contributions within peptide segments that serve as a biomimetic template for diacetylene polymerization in water. We investigated the functional impacts of molecular volume and polarity changes brought by dipeptide substitution domains on the following peptide-PDA material properties at multiple length scales: supramolecular assembly behavior, chain conformation-dependent photophysical properties, cell-material interfacing, and for the first time, bulk electrical properties of their films processed in water. A library of peptide-PDAs with systematically varied sequences show that the contributions of steric effects predominantly influence the electronic structure and resulting trends in photophysical properties, while the interplay between size and hydrophobicity of individual residues becomes more significant for higher-order assemblies affecting bulk properties. This work demonstrates sequence-tunable molecular volume and polarity as synthetic handles to rationally modulate PDA material properties across length scales, providing insights into the programmability of biomimetic conjugated polymers with adaptive functionalities.

The alkaline hydrogen oxidation reaction (HOR) involves the coupling of adsorbed hydrogen (Had) and hydroxyl (OHad) species and is thus orders of magnitude slower than that in acid media. According to the Sabatier principle, developing electrocatalysts with appropriate binding energy for both intermediates is vital to accelerating the HOR though it is still challenging. Herein, we propose an unconventional bilateral compressive strained Ni–Ir interface (Ni–Ir(BCS)) as efficient synergistic HOR sites. Density functional theory (DFT) simulations reveal that the bilateral compressive strain effect leads to the appropriate adsorption for both Hadand OHad, enabling their coupling thermodynamically spontaneous and kinetically preferential. Such Ni–Ir(BCS) is experimentally achieved by embedding sub-nanometer Ir clusters in graphene-loaded high-density Ni nanocrystals (Ni–Ir(BCS)/G). As predicted, it exhibits a HOR mass activity of 7.95 and 2.88 times those of commercial Ir/C and Pt/C together with much enhanced CO tolerance, respectively, ranking among the most active state-of-the-art HOR catalysts. These results provide new insights into the rational design of advanced electrocatalysts involving coordinated adsorption and activation of multiple reactants.

The gear fault signal is characterized by strong and/or weak impulsive features and is often accompanied by strong background noise, which makes the gear fault feature extraction more difficult. Hence, this article proposes a new time-frequency analysis (TFA) method called the tensor denoising (TD) assisted time-reassigned synchrosqueezing wavelet transform (TD-TSWT). First, to improve the accuracy of subsequent TFA, a TD method based on high-order singular value decomposition (HOSVD) is proposed as a preprocessing technique according to the cyclostationary characteristics of gear faults and the Hankel matrix. Meanwhile, combined with the advantages of sample entropy calculation, the concept of using sample entropy to determine the reasonable singular order is proposed. Second, to propose TSWT for revealing gear fault features. TSWT by introducing continuous wavelet transform (CWT) to obtain the basis function which is more similar to gear fault impulses. Moreover, according to the properties of the gear fault signal, the group delay estimation operator in the frequency domain is designed for TSWT, which is more suitable for the gear fault feature extraction. Finally, the results of simulations and engineering cases show that the method provides a useful tool for the diagnosis of gear faults.

The luminescence of organic semiconductor materials is the key function for their lighting and display applications. Continuous regulation of emission colors based on one organic molecule system is still a challenge because of their individual emission band. Here we present a novel strategy for modulation of crystal nuclei and growth rates for different crystal phases, which contributes to fine synthesis of the organic polymorph-based alloy microwires that successfully exhibit continuous regulation of emission colors from blue to green. High supersaturation facilitates formation of α-phase microwires with blue emission (CIE [0.17, 0.23]), and low supersaturation is beneficial for self-assembly of β-phase microwires with green emission (CIE [0.29, 0.58]). Impressively, these organic polymorph-based alloy microwires were applied successfully to multicolor display and optical waveguides, which offer potential applications as continuous multicolor emitters for advanced photonics.

With the potential to circumvent the need for scarce and cost-prohibitive platinum-based catalysts in proton-exchange membrane fuel cells, anion-exchange membrane fuel cells (AEMFCs) are emerging as alternative technologies with zero carbon emission. Numerous noble metal-free catalysts have been developed with excellent catalytic performance for cathodic oxygen reduction reaction in AEMFCs. However, the anodic catalysts for hydrogen oxidation reaction (HOR) still rely on noble metal materials. Since the kinetics of HOR in alkaline media is 2–3 orders of magnitude lower than that in acidic media, it is a major challenge to either improve the performance of noble metal catalysts or to develop high-performance noble metal-free catalysts. Additionally, the mechanisms of alkaline HOR are not yet clear and still under debate, further hampering the design of electrocatalysts. Against this backdrop, this review starts with the prevailing theories for alkaline HOR on the basis of diverse activity descriptors, i.e., hydrogen binding energy theory and bifunctional theory. The design principles and recent advances of HOR catalysts employing the aforementioned theories are then summarized. Next, the strategies and recent progress in improving the antioxidation capability of HOR catalysts, a thorny issue which has not received sufficient attention, are discussed. Moreover, the significance of correlating computational models with real catalyst structure and the electrode/electrolyte interface is further emphasized. Lastly, the remaining controversies about the alkaline HOR mechanisms as well as the challenges and possible research directions in this field are presented.

BN-embedded polycyclic aromatic hydrocarbons (PAHs) with unique optoelectronic properties are underdeveloped relative to their carbonaceous counterparts due to the lack of suitable and facile synthetic methods. Moreover, the dearth of electron-deficient BN-embedded PAHs further hinders their application in organic electronics. Here we present the first facile synthesis of novel perylene diimide derivatives (B2N2-PDIs) featuring n-type B–N covalent bonds. The structures of these compounds are fully confirmed through the detailed characterizations with NMR, MS, and X-ray crystallography. Further investigation shows that the introduction of BN units significantly modifies the photophysical and electronic properties of these B2N2-PDIs and is further understood with the aid of theoretical calculations. Compared with the parent perylene diimides (PDIs), B2N2-PDIs exhibit deeper highest occupied molecular orbital energy levels, new absorption peaks in the high-energy region, hypsochromic shift of absorption and emission maxima, and decrement of photoluminescent quantum yields. Single-crystal field-effect transistors based on B2N2-PDIs showcase an electron mobility up to 0.35 cm2V–1s–1, demonstrating their potential application in optoelectronic materials.

The low doping efficiency of n‐doped systems limits the development of n‐type organic conducting materials. Oligo(ethylene glycol) (OEG) as the flexible chain in conjugated small molecules and polymers may improve doping efficiency. However, OEG side chains also bring unexpected low mobility and poor film morphology. Herein, we propose the stronger solution‐state aggregation plays a dominated role in charge transport and morphology of OEG‐substituted polymer. The solution‐state aggregation also affects doping process. Therefore, we develop a series of polymers based on 3,7‐bis((E)‐7‐fluoro‐1‐(2‐octyldodecyl)‐2‐oxoindolin‐3‐ylidene)‐3,7‐dihydrobenzo[1,2‐b:4,5‐b']difuran‐2,6‐dione (FBDPPV) with different ratios of OEG side chain to investigate the effect of side chain on solution‐state aggregation and n‐doping process. After n‐doped by hexahydro‐1H,3a1H,4H,7H‐3a,6a,9a‐triazaphenalene (TAM), FBDPPV with 50% OEG affords the highest doping efficiency and conductivity, while FBDPPV with 100% OEG shows lower conductivity. Combination of ultraviolet–visible–near infrared absorption spectra, grazing‐incidence wide‐angle X‐ray scattering and atomic force microscopy, we reveal that serious aggregated extent in solution of OEG‐substituted polymer result in phase separation and rough morphology, which are the origins of poor conductivity. Our work provides a new perspective on the effect of the OEG side chain on the doped polymer systems, suggesting suitable solution‐state aggregation is crucial to high doping efficiency and high conductivity.

The aggregation behaviors of conjugated polymers significantly influence their performance in solution-processed optoelectrical devices. Traditionally, the formation of aggregates from the self-assembly of conjugated polymers is considered as a thermodynamic equilibrium process. The abundant degree of conformation freedom of conjugated polymers might lead to complex aggregation behaviors in solution. However, the energy landscape of conjugated polymers during aggregation has rarely been studied before, which would provide the energetic and structural information about different aggregates. Our work tried to unravel the energy landscape of conjugated polymers during aggregation and investigate the energetic and structural information of the thermodynamically and kinetically stable aggregates in solution. Herein, kinetically and thermodynamically stable aggregates of naphthalene diimide (NDI)-based polymers are obtained through rational molecular design and thermodynamic control. Investigation of the theoretical calculation, photophysical properties, and morphologies of the conjugated polymers demonstrates the formation of and differences between kinetically and thermodynamically stable aggregates. The energetic and structural analysis of kinetically and thermodynamically stable aggregates here provide insight into the relations among the structure, morphology, and properties of conjugated polymers at the molecular level. This work demonstrates the energy landscape of conjugated polymers during aggregation and further extends our understanding of the aggregation mechanisms.

The low n-doping efficiency of conjugated polymers with the molecular dopants limits their availability in electrical conductivity, thermoelectrics, and other electric applications. Recently, considerable efforts have focused on improving the ionization of dopants by modifying the structures of host polymers or n-dopants; however, the effect of ionized dopants on the electrical conductivity and thermoelectric performance of the polymers is still a puzzle. Herein, we try to reveal the role of molecular dopant cations on carrier transport through the systematic comparison of two n-dopants, TAM and N-DMBI-H. These two n-dopants exhibit various doping features with the polymer due to their different chemical structure characteristics. For instance, while doping, TAM negligibly perturbs the polymer backbone conformation and microstructural ordering; then after ionization, TAM cations possess weak π-backbone affinity but strong intrinsic affinity with side chains, which enables the doped system to screen the Coulomb potential spatially. Such doping features lead to high carrierization capabilities for TAM-doped polymers and further result in an excellent conductivity of up to 22 ± 2.5 S cm–1and a power factor of over 80 μW m–1K–2, which are significantly higher than the state of the art values of the common n-dopant N-DMBI-H. More importantly, this strategy has also proven to be widely applicable in other doped polymers. Our investigations indicate the vital role of dopant counterions in high electrical and thermoelectric performance polymers and also suggest that, without sacrificing Seebeck coefficients, high conductivities can be realized with precise regulation of the interaction between the cations and the host.

The molecular conformation and packing mode of organic radicals are vital to achieving distinctive electronic, spin relaxation, and magnetic properties. Herein two organic radicals, B2P and B4P, are developed by attaching a 6-oxoverdazyl radical at different peripheral positions of [1]benzothieno[3,2-b][1]benzothiophene (BTBT). B2P single crystals exhibit a typical herringbone packing mode, whereas B4P single crystals display a classic brick-layer stacking structure. Moreover, two crystalline phases, B4P-Y and B4P-R, are observed in B4P crystals owing to the rotational isomerization. Because of the distinct molecular conformation and packing structures, the spin relaxation behaviors of the two 6-oxoverdazyl radicals are significantly different, and B4P-Y with a distorted conformation exhibits a longer spin relaxation time.

n-Doped conjugated polymers usually show low electrical conductivities and low thermoelectric power factors, limiting their applications in n-type organic thermoelectrics. Here, we report the synthesis of a new diketopyrrolopyrrole (DPP) derivative, pyrazine-flanked DPP (PzDPP), with the deepest LUMO level in all the reported DPP derivatives. Based on PzDPP, a donor–acceptor copolymer, P(PzDPP-CT2), is synthesized. The polymer displays a deep LUMO energy level and strong interchain interaction with a short π–π stacking distance of 3.38 Å. When doped with n-dopant N-DMBI, P(PzDPP-CT2) exhibits high n-type electrical conductivities of up to 8.4 S cm–1and power factors of up to 57.3 μW m–1K–2. These values are much higher than previously reported n-doped DPP polymers, and the power factor also ranks the highest in solution-processable n-doped conjugated polymers. These results suggest that PzDPP is a promising high-performance building block for n-type organic thermoelectrics and also highlight that, without sacrificing polymer interchain interactions, efficient n-doping can be realized in conjugated polymers with careful molecular engineering.

A compact D–D neutron generator, with a peak neutron yield of D–D reactions up to 2.48 × 108n/s is being developed at Lanzhou University in China for application in real-time neutron activation analysis. During tests, the problem of back acceleration of secondary electrons liberated from the neutron production target by deuterium ions bombardment was encountered. In this study, an electric field method and a magnetic field method for suppressing secondary electrons are designed and experimentally investigated. The experimental results show that the electric field method is superior to the magnetic field method. Effective suppression of the secondary electrons can be achieved via electrostatic suppression when the bias voltage between the target and the extraction-accelerating electrode is > 204 V. Furthermore, the secondary electron emission coefficient for the mixed deuterium ion (D1+, D2+, and D3+) impacting on molybdenum is estimated. In the deuterium energy range of 80–120 keV, the estimated secondary electron emission coefficients are approximately 5–5.5 for the mixed deuterium ion glancing incidence of 45° and approximately 3.5–3.9 for the mixed deuterium ion normal incidence.

Continuous band structure tuning, e.g., doping with different atoms, is one of the most important features of inorganic semiconductors. However, this can hardly be realized in organic semicondutors. Here, we report the first example of fine-tuning organic semiconductor band structures by alloying structurally similar derivatives into one single phase. By incorporating halogen atoms on different positions of the backbone, BDOPV derivatives with complementary intramolecular or intermolecular charge distributions were obtained. To maximize the Coloumbic attractive interactions and minimize repulsive interactions, they form antiparallel cofacial stacking in monocomponent or in alloy single crystals, resulting in efficient π orbital overlap. Benefiting from self-assembly induced solid state “olefin metathesis” reaction, it was observed, for the first time, that three BDOPV derivatives cocrystallized in one single crystal. Molecules with different energy levels serve like the dopants in inorganic semiconductors. Consequently, as the total number of halogen atoms increased, highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels of the alloy single crystals decreased monotonously in the range from −5.94 to −6.96 eV and −4.19 to −4.48 eV, respectively.

The recovery of natural gas from CH4hydrate deposits in permafrost environments through injection of CO2is considered to be a suitable strategy for CH4production and CO2storage. To study the replacement characteristics of CO2–CH4hydrate below the freezing point, the experiment was conducted in ice powder with particle size of 800 μm at different injection pressures (3.6, 4.0, and 4.5 MPa) of CO2. The experimental results showed that the average replacement rate and efficiency increased with the increasing of injected pressure of CO2gas. Also, the average replacement rate and efficiency reached up to 0.403 mmol/h and 13.20% when the injected pressure of CO2was at 4.5 MPa. The results also indicated that, compared with the temperature conditions above the freezing point, the replacement rate of CO2–CH4hydrate was slow below the freezing point. These results provide a theoretical guidance for gas production from methane hydrate using CO2–CH4replacement method in permafrost region in the future.

The complex non-centrosymmetric and chiral nature of helical structures endow materials that possess such motifs with unusual properties. However, despite their ubiquity in biological and organic systems, there is a severe lack of inorganic crystals that display helicity in extended lattices, where these unusual properties are expected to be most pronounced. Here, we report a new inorganic helical structure, gallium sulfur iodide (GaSI), within the exfoliable class of III–VI–VII (1:1:1) one-dimensional (1D) van der Waals (vdW) crystals. Through detailed structural analyses, including single-crystal X-ray diffraction, electron microscopy, and density functional theory (DFT), we elucidate the apparent noncrystallographic screw axis and the first example of an atomic scale helical structure bearing a “squircular” cross-section in GaSI. Crystallizing in the non-centrosymmetric P4̅ space group, we found that GaSI crystals exhibit pronounced second-harmonic generation. From diffuse reflectance spectroscopy, GaSI displays a sizeable bandgap of 3.69 eV, owing tostrong covalent interactions arising from the smaller sulfur atoms within the helix core. These results position GaSI as a promising exfoliable nonlinear optical material across a broad optical window.

Because of their resolvable crystal structure, organic conjugated small molecules are intrinsically ideal for elucidating the relationship between microstructures and charge transport properties. It has been reported that the charge transport properties depend on molecular structure and molecular packing. In the solid state, π–π stacking of small molecules is significant in the charge transport process. Since π–π stacking of conjugated small molecules is influenced at different degrees by other intra- and intermolecular interactions, as a result, π–π stacking and further the charge transport properties can be controlled or tuned by crystal engineering through precise chemical modification. In this perspective, we give some typical examples illustrating the strategy of controlling π–π stacking in single crystals. Furthermore, we attempt to clarify the complex relationship between π–π stacking and other types of molecular interactions, and its influence on charge transport properties.

The transport characteristics of a space charge-dominated multi-species deuterium beam consisting of $$ D_{1}^{ + } $$ D1+ , $$ D_{2}^{ + } $$ D2+ , and $$ D_{3}^{ + } $$ D3+ particles in an electrostatic low-energy beam line are studied. First, the envelope equations of the primary $$ D_{1}^{ + } $$ D1+ beam are derived considering the space charge effects caused by all particles. Second, the evolution of the envelope of the multi-species deuterium beam is simulated using the PIC code TRACK, with the results showing a significant effect of the unwanted beam on the transport of the primary beam. Finally, different injected beam parameters are used to study beam matching, and a new beam extraction system for the existing duoplasmatron source is designed to obtain the ideal injected beam parameters that allow a $$ D_{1}^{ + } $$ D1+ beam of up to 50 mA to pass unobstructed through the electrostatic low-energy beam transport line in the presence of an unwanted ($$ D_{2}^{ + } $$ D2+ , $$ D_{3}^{ + } $$ D3+ ) beam of 20 mA; at the same time, distortions of the beam emittance and particle distributions are observed.

Picking robot is the inevitable trend of the development of orchard harvester technology in the future. However, automatic apple picking technology is difficult to achieve because of uncertainty in distribution, inconsistent maturity, and uneven quality and other issues. It is hard to locate the position of apples accurately. Therefore, after summarizing the advantages and disadvantages of apple harvesting technology at laboratory and abroad, a picking device was designed. The device is based on the purpose of distinguishing the maturity of apples and consists of shell, cutting device, power device. It can achieve efficient and rapid fruit picking and more accurate differentiation of maturity. For other similar spherical fruit also has some applicability.

Knowledge of actinides (n,f) fission process induced by neutron is of importance in the field of nuclear power and nuclear engineering, especially for reactor applications. In this work, fission characteristics of 238U(n,f) reaction induced by D-T neutron source were simulated with Geant4 code from multiple perspectives, including the fission production yields, total nubar, kinetic energy distribution, fission neutron spectrum and cumulative γ-ray spectrum of the fission products. The simulation results agree well with the experimental nuclear reaction data (EXFOR) and evaluated nuclear data (ENDF). Mainly, this work was to examine the rationality of the parametric nuclear fission model in Geant4 and to direct our future experimental measurements for the cumulative fission yields of 238U(n,f) reaction.

Electrocatalytic CO2reduction (ECR) to high-value fuels and chemicals offers a promising conversion technology for achieving sustainable carbon cycles. In recent years, although great efforts have been made to develop high-efficiency ECR catalysts, challenges remain in achieving high activity and long durability simultaneously. Taking advantage of the adjustable structure, tunable component, and the M–Ch (M = Sn, In, Bi, etc., Ch = S, Se, Te) covalent bonds stabilized metal centers, the p-block metal chalcogenides (PMC) based electrocatalysts have shown great potential in converting CO2into CO or formates. In addition, the unique p-block electron structure can suppress the competitive hydrogen evolution reaction and enhance the adsorption of ECR intermediates. Seeking to systematically understand the structure–activity relationship of PMC-based ECR catalysts, this review summarizes the recent advances in designing PMC electrocatalysts for CO2reduction based on the fundamental aspects of heterogeneous ECR process, including advanced strategies for optimizing the intrinsic activity and improving the loading density of catalytic sites, constructing highly stable catalysts, and tuning product selectivities. Subsequently, we outline the challenges and perspectives on developing high-performance PMC ECR catalysts for practical applications.

The high-temperature flow behavior of TC11/Ti–22Al–25Nb electron beam (EB) weldments was investigated by the isothermal compression tests at the temperature of 900–1060 °C and the strain rate of 0.001–10 s−1. Based on the experimental data, the constitutive equation that describes the flow stress as a function of strain rate and deformation temperature is obtained. The apparent activation energy of deformation is calculated, which decreases with increasing the strain and the value is 334 kJ/mol at strain of 0.90. The efficiency of power dissipation ηchanges obviously with the variation of deformation conditions. Under the strain rates of 0.01, 0.1 and 1 s−1, the value of ηincreases with increasing the true strain for different deformation temperatures. While the value of ηdecreases with increasing the strain under the strain rates of 0.001 and 10 s−1. The optimum processing condition is (topi=1060 °C, opi=0.1 s−1) with the peak efficiency of 0.51. Under this deformation, dynamic recrystallization (DRX) is observed obviously in the microstructure of welding zone. Under the condition of 1060 °C and 0.001 s−1, the deformation mechanism is dominated by dynamic recovery (DRV) and the value of ηdecreases sharply (η=0.02). The flow instability is predicted to occur since the instability parameter ξ() becomes negative. The hot working process can be carried out safely in the domain with the strain rate of 0.001–0.6 s−1and the temperature of 900–1060 °C.

Microstructure and tensile properties of TC21 titanium alloy after near-isothermal forging with different parameters plus solution treatment and aging were investigated. It is found that the residual βmatrix, which was strengthened by fine secondary αplatelets forming during aging, exists in all the samples; while primary equiaxed αphase, bent lamellar αphase and αplates are simultaneously or individually present in one sample. The strength of alloy increases proportionally with increasing the content of residual βmatrix, which is the result of increasing α/βinterphase boundary. The plasticity of alloy has a downward trend as the content of residual βmatrix increases. This attributes to the increase of fine secondary αplatelets, which are cut by dislocations during the deformation. Additionally, coarse αplates with long axis parallel to the maximum resolved shear stress (MRSS) also reduce the plasticity of TC21 alloy.

The influence of hot working on the microstructures of TC11/Ti2AlNb dual-alloy joints welded by electron beam welding (EBW) process was investigated. The tensile tests were performed at room temperature for specimens before and after thermal exposure. The results show that the fusion zone of TC11/Ti2AlNb dual-alloy joint welded by EBW is mainly composed of βphase. After deformation and heat treatment, the grain boundaries of the as-cast alloy are broken and the fusion zone mainly consists of β, α2and αphases. The fusion zone performs poor property in the tensile test. Specimens before and after thermal exposure all fail in this area under different deformation conditions. The ultimate tensile strength of specimens after heat treatment is up to 1190 MPa at room temperature. The joints by water quenching after deformation have better plasticity with an elongation up to 4.4%. After thermal exposure at 500 °C for 100 h, the tensile strength of the specimen slightly rises while the ductility changes a little. SEM observation shows that the fracture mechanism is predominantly transgranular under different deformation conditions.

This study investigates the superplastic deformation mechanism of coarse-grain materials .Superplasticity deformation behavior of Ti-22Al-25Nb alloy with 200~410μm coarse grain has been investigated through tensile test at 940~990°C and 3.3× (10-2~10-4) s-1 strain rate. Results prove coarse-grain Ti-22Al-25Nb alloy primary depends on slipping of crystal planes between two phases to achieve superplasticity. Transformation from lath O phase to ring equiaxed O phase occurs as temperature rises and its volume percent falls, but percentage of recrystallized B2 phase increases. Dislocation can move round ring equiaxed O phase. Good plasticity can be preserved because O phase can flow as solid particle in semisolid slurry in B2 grain.

According to the unit price, the section capacity section and the data of ramp rate, in accordance with the electricity market rules, the pushing method and optimal search model of the next time the output of the unit distribution plan are established.

During near isothermal forging and heat treatment structure change of bonding interface in Ti3Al/TC11 and Ti2AlNb/TC11 dual alloys jointed with different method has been investigated. The results show that the solidification structure at dual-alloy joint welded by electron beam in vacuum has evolved into forging structure, columnar grains have been changed into equiaxed grains through breaking, crystal lattatice rebuild and re-crystallizing, and the mechanical bonding plus metallurgical bonding structure at joint welded by linear friction weld has transformed into metallurgy structure altogether, because constant high temperature during near isothermal forging can cause the diffusion of alloy elements and reconstruction of lattice structure.

TG6 alloy is a new titanium alloy which has been designed to reach the service temperature of 600°C. The microstructural evolutions of TG6 alloy under different thermal mechanical treatments were studied. It was found that lamellar microstructures with basketweave α lamella are obtained for TG6 alloy forged in β field. The evolution mechanism is transformed from dynamic recrystallization to dynamic recovery and the thickness of α lamella increases with increasing forging temperature. The aspect ratio of α lamella decreases firstly and then increases with increasing deformation degree. Grain boundary α lath appears when the deformation degree is less than 40%. The thermal mechanical treatments, including deformation in β field firstly and then deformation in α+β field result in the transformations of the microstructures drastically. The deformation degree in α+β field decides the final microstructure. The deformation degree of 20% in α+β field results in partial globular α phase.

Garbage sorting robot, which consists of development platform, power supply module, object detecting module, some control modules, and so on, is presented in this paper. This research focuses on control architecture of garbage sorting robot including mechanical hand control, positioning algorithm and recognition algorithm. The garbage sorting robot and its control algorithm have been demonstrated and verified through the contest.

In this paper the method of Linear Quadratic Regulator (LQR) is employed for controlling accelerator PWM power supply, and improving its dynamic functioning. A method based on the Particle Swarm Optimization is proposed to optimize the weighting matrix Q and R. In order to control the dynamic behavior of the power supply, the fitness function of PSO is acquired considering the needs of the power properties. The results of simulation proved that the proposed method was much better than simple LQR method and LQR-GA method, and the performance of the power supply was improved dramatically.

Air cooled thermal power structure is composed of spatial steel truss and steel-concrete tubular columns. Permeable “A” shape structure and wind-break wall are installed on its top. The wind load in the wind-break wall has great effect on its lower part. The structural wind parameters is not clearly stipulated in current load code. To solve the problems of wind parameter value in design and effectively evaluate the influence on wind-break wall form to the structural wind-resistant properties, three different wind-break wall forms are presented. Wind properties on an actual air cooled thermal power structure under three different wind–break wall forms are simulated with FLUENT software. Wind pressure law on “A” type structure and wind-break wall under different wind-break wall forms and at different wind direction angles is studied. Every division section shape coefficient of wind-break wall and “A” type structure under different conditions is obtained. The wind presure distribution law and the most reasonable wind-break wall form is obtained.

The Ti3Al/TC11 dual alloy bar joined by electron beam welding was deformed by near isothermal forging and then processed by gradient heat treatment. Afterwards, the mechanism of interface strengthening has been investigated according to the microstructure evolution and properties. The results show the brittle phases formed in the re-solidification can be broken by near isothermal forging; the lattice distortion energy is increased obviously due to deformation, so the nucleation ratio of recrystallization is improved, which method is fine-crystal strengthening. After the dual alloy deformed by near isothermal forging is further processed by gradient heat treatment, the room temperature tensile strength of the joint is higher than that of the Ti3Al alloy; the high temperature tensile strength of the joint is equal to or higher than that of the TC11 alloy. The reason is that the finer and phases are precipitated from the phase transus microstructure in the welding interface, which produces the effects of fine-crystal strengthening and dispersion strengthening.

The primary purpose of the present work is to investigate the effects of annealing after equal channel angular pressing (ECAP) on microstructure and microhardness of TA15 titanium alloy. A study was performed by annealing treatment on the microstructure evolution and microhardness variation of ECAPed TA15 alloy. The results state that, static recrystallization occurred distinctly during annealing after ECAP. Since a sample was annealed at a proper temperature and for proper time after ECAP, a larger amount of well globularized and more homogeneous equiaxed α phase has been attained, grains have not grown observably, and the relief of residual stress and work hardening for subsequent processing and using has also been achieved. Accordingly, the optimum annealing parameters of ECAPed TA15 alloy were optimized to be 973 K and 1 hour. The microhardness level of the sample annealed after ECAP was lower than that unannealed, and the microhardness level decreased with the increasing annealing temperature and time.

The steel-concrete hybrid structure is a new special industrial structure in large thermal power plants. It is composed of a spatial steel truss and steel-concrete tubular columns. Its stiffness and mass is highly non-uniform at vertical direction. Its temperature effect is obvious because its steel truss is a high order statically indeterminate structure. Types and characteristics of temperature load prescribed in codes are introduced. Temperature effect of the steel-concrete hybrid structure is calculated by FEM analysis software SAP2000 in four different supporting blocks. The structural internal force and distortion under temperature effect is analyzed. The influence of supporting blocks on the structual temperature effect is analyzed. The structural supporting block form to advantageously release its temperature effect is presented. Some advice is presented based on the analysis results.

A study was conducted by optical microscope (OM) and transmission electron microscope (TEM) on the microstructure evolution of TA15 alloy by severe plastic deformation (SPD) and annealing after SPD. In this study, equal channel angular pressing (ECAP) was taken as the method of SPD. The chief aim of the present work is to investigate the temperature effects of ECAP and annealing after ECAP on microstructure of TA15 alloy. The results indicate that equiaxed microstructure has been obtained by ECAP at the temperatures of α+β phase region, and that with the increase in pressing temperature, equiaxed grains have become coarser and the content of α phase has reduced. β grains have been coarsened severely since the pressing temperature was above the α-β transformation temperature (Tβ). Annealed at proper temperature after ECAP, the α phase of TA15 alloy has been more homogeneous, prior α phase has been well globularized, and grains have not grown obviously. According to the testing of TA15 alloy, the optimized temperature parameters of ECAP and annealing after ECAP are 900℃ and 700℃. Observation and Analysis of the TEM morphological images illustrate that a quantity of twinning deformations have been produced by ECAP at the temperatures below Tβ, which leads to the continued plastic deformation through the restarting of many slip bands.

In this paper the effect of isothermal forging process parameters on the microstructure and the mechanical properties of Ti-5Al-5Mo-5V-1Cr-1Fe titanium alloy was researched. The results of the tests indicate that, in the temperature range of 755~905 ºC and the deformation degree range of 20~60 %, with the increase of deforming temperature, the volume of primary α-phases decrease, but the globularization extent of the α-phases increases and partial secondary α-phases transform into equiaxed shape. At the temperature of 860 ºC, the alloy exhibits excellent strength and plasticity, as the uniform and fine duplex microstructure formed after isothermal forging. When the deformation degree increased from 20% to 60%, primary and secondary α-phases were gradually broken and the recrystallization energy was continually accumulated, which ceaselessly strengthened the properties of the alloy. With the increase of forging times, the globularization extent of decreases, leaving the chain of α-phases, which damages the strength and plasticity of the alloy.

Thermomechanical treatment (TMT) of PM FGH4096 superalloy were carried out to futher improve the mechanical strength and refine the γ’ particle, and this processing route as follows: near-isothrmal forged at deformation temperature of 1130℃ and strain rate of 0.1 s-1, followed by subsequence oil quenching, and then held at 760℃ for 16 h. OM, SEM and TEM were used to investigate the microstructure of TMTed alloy. It was found that the advanced mechanical strength originated form the dispersion strengthening of fine γ’ particle and stain hardening reserved from deformation after TMT. But TMT had no obvious effect on improving the chemical segregation of original materials. Fracture analysis of TMTed alloy shown that cracks origined from Ti and Nb chemical segregation and presented rose-pattern and ladder-pattern at room temperature and 750℃ temperature.

The microstructures and room temperature and 600°C tensile properties of Ti-5.8Al-4.0Sn-4.0Zr-0.7Nb -0.4Si-1.5Ta alloy after isothermal forging have been studied. The forging temperature range was from 850°C to 1075°C, and the constant strain rate of 8×10-3/S-1 was adopted. With the increase of forging temperature, the volume fraction of primary α phase decreased and the lamellar α phase became thicker when the temperatures were in range of 850°C -1040°C; The grain size became uneven and the α phase had different forms when the forging temperature was 1040°C and 1075°C respectively; The tensile strength was not sensitive to the temperature and the most difference was within 20MPa. Tensile strength and yield strength attained to the maximum when temperature was 1020°C; the ductility decreased with the increase of forging temperature, and this trend became more obvious if forging temperature was above the β-transus temperature.

The influences of different hot working conditions on the microstructures and mechanical properties at weld zone of the Ti3Al/TC4 dual alloy have been investigated. The experimental results show that forging and heat treatment has significant influence on room temperature tensile strength (RTTS for short) of the weld zone. The influence of forging strain and temperature on its elongation at temperature 500ºC is also conspicuous. The results of intuitional and variance analysis show that affecting factors of its RTTS are heat treatment, forging strain, forge temperature and condition of billet in sequence. The affecting factors of its room temperature (RT for short) ductility and the tensile strength (TS for short) at temperature 500 ºC are forging strain, forge temperature, heat treatment and condition of billet. Good comprehensive properties are obtained under optimal conditions: forging at 1020ºC, annealing at 700ºC for 12 hours, air cooled, about 40% strain and as-rolled billet. The microstructures of the weld zone worked according as those conditions are uniform and the grain size is also fine.

Dissimilar joining of Ti-22Al-25Nb alloy and an α+β titanium alloy TC11 were carried out using electron beam process and linear friction process, respectively. The microstructure and tensile properties of the joints were investigated. The results show that both EBW and LFW could be adopted to the dissimilar joining of Ti-22Al-25Nb/TC11. The EB welded joint exhibits higher strength than that of the LF welded joint, due to the precipitation of O phase in the fusion zone of the former one. These results can be expected to be of great technical interest as basic data for the use of EBW or LFW in aerospace industry.

Ultrafine-grained treatment (multiple forging and heat treatment) were carried out on FGH4096 alloy to get ultrafine grain with grain being of 1-5μm. OM, SEM, TEM and tensile test were used to study the action of ultrafine-grained treatment on improving structure and properties. The tensile properties of the alloy processed under ultrafine-grained treated have shown quite satisfactory levels, which ultimate strength (UTS) reach 1730Mpa and yield strength (YS) values reach 1470Mpa at room temperature. The apperance of advanced strength has originated chiefly form not only the persence of fine grains, but also structure of grain boundaries and diaperce pricipitations of secondary phase. A better combination of mechanical properties achieved by use of ultrafine-grained treatment makes it possible to explore the dual property turbine disc to its maximum potential for FGH 4096 alloy.