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Charge generation layers (CGLs) play crucial roles in determining the electroluminescence (EL) performance of tandem organic light-emitting diodes (OLEDs). However, acquiring negligible voltage drops across the CGL unit and high-efficiency multiplications remains challenging. Here, we propose barrier-free strategies to compose a high-performance p-i-n type CGL intermediate by introducing a Yb/HI-9 modification at the heterojunction and a novel n-dopant, Yb:1,3-bis(9-phenyl-1,10-phenanthrolin-2-yl)benzene (mdPPhen), as the n-CGL. Mechanism analysis confirms that the Yb/HI-9 modification efficiently eliminates the intrinsic energy mismatch at the n-CGL/p-CGL interface, while the lowest unoccupied molecular orbital (LUMO) of the n-dopant can be aligned to the electron transport layer of adjacent EL units, creating improved electron transport. Consequently, the resulting 2-EL unit tandem OLEDs exhibited no voltage drops across the CGL intermediate with excellent efficiency multiplications. Notably, the barrier-free CGL strategy worked efficiently in the sensitized fluorescence tandem OLED with low operating voltage, extremely high efficiency (current efficiency of 267.2 cd/A, external quantum efficiency of 62.6%), and operational stability (95% of the initial luminance at 3000 cd/m2, T95 of 4713 h) with pure-green emission (CIEy coordinate of over 0.68), showing the best tandem OLED among reported CGLs to satisfy commercial demands.

By considering a certain metro station of Qingdao Metro Line 4 as the research object, a three-dimensional geotechnical testing model has been developed to analyze the stress and deformation characteristics of the surrounding rocks under blasting vibration effect. The simulation of the surrounding rock blasting process is achieved through an electric spark source. We conducted simulation tests on the excavation stability of shallow-buried hard rock metro stations with and without considering blasting damage effects, respectively. The stress, displacement, and primary support stress changing laws of the surrounding rock under different overburden thicknesses using the arch cover method and the primary support arch cover method have been revealed. Finally, we analyzed the applicability of the primary support arch cover method in terms of vault settlement, clearance convergence, and floor heave. Results show that the surrounding rock of the arch has roughly gone through three deformation stages, namely a slow deformation stage, rapid deformation stage, and stable deformation stage. Whether it is blasting excavation or non-blasting excavation, the settlement of the arch is within a safe and controllable range. Because of the refinement of the excavation process by the primary support arch cover method, the stress release is relatively stable throughout the entire excavation process, but the significant impact of blasting vibration on the surrounding rock cannot be ignored. The excavating of the left and right guide holes is the key process for the displacement and stress variation. The deformation and stress generated by the arch cover method have a small difference compared to the deformation and stress generated by the primary support arch cover method, indicating that the latter excavation method can be used under current engineering geological conditions. No large-area collapse and instability occurred in the experimental process, which provides a theoretical basis for similar projects.

Global climate change has led to the decline of species and functional diversity in ecosystems, changing community composition and ecosystem functions. However, we still know little about how species with different resource-use strategies (different types of resource usage and plant growth of plants as indicated by the spectrum of plant economic traits, including acquisitive resource-use strategy and conservative resource-use strategy) would change in response to climate change, and how the changes in the diversity of species with different resource-use strategies may influence community-level productivity. Here, using long-term (1982–2017) observatory data in a temperate grassland in Inner Mongolia, we investigated how climate change had affected the species richness (SR) and functional richness (FRic) for the whole community and for species with different resource-use strategies. Specifically, based on data for four traits representing leaf economics spectrum (leaf carbon concentration, leaf nitrogen concentration, leaf phosphorus concentration, and specific leaf area), we divided 81 plant species appearing in the grassland community into three plant functional types representing resource-acquisitive, medium, and resource-conservative species. We then analyzed the changes in community-level productivity in response to the decline of SR and FRic at the community level and for different resource-use strategies. We found that community-level SR and FRic decreased with drying climate, which was largely driven by the decline of diversity for resource-acquisitive species. However, community-level productivity remained stable because resource-conservative species dominating this grassland were barely affected by climate change. Our study revealed distinctive responses of species with different resource-use strategies to climate change and provided a new approach based on species functional traits for predicting the magnitude and direction of climate change effects on ecosystem functions.

The Convention on Biological Diversity seeks to conserve at least 30% of global land and water areas by 2030, which is a challenge but also an opportunity to better preserve biodiversity, including flowering plants (angiosperms). Herein, we compiled a large database on distributions of over 300,000 angiosperm species and the key functional traits of 67,024 species. Using this database, we constructed biodiversity-environment models to predict global patterns of taxonomic, phylogenetic, and functional diversity in terrestrial angiosperms and provide a comprehensive mapping of the three diversity facets. We further evaluated the current protection status of the biodiversity centers of these diversity facets. Our results showed that geographical patterns of the three facets of plant diversity exhibited substantial spatial mismatches and nonoverlapping conservation priorities. Idiosyncratic centers of functional diversity, particularly of herbaceous species, were primarily distributed in temperate regions and under weaker protection compared with other biodiversity centers of taxonomic and phylogenetic facets. Our global assessment of multifaceted biodiversity patterns and centers highlights the insufficiency and unbalanced conservation among the three diversity facets and the two growth forms (woody vs. herbaceous), thus providing directions for guiding the future conservation of global plant diversity.

This paper investigates the uplink energy efficiency (EE) of a wireless-powered cell-free massive multiple-input multiple-output (mMIMO) system with hardware impairments, considering Rician fading and maximum ratio processing, anchored in linear minimum mean-squared error (LMMSE) channel estimation. The transceivers of access points (APs) and user equipments (UEs) are non-ideal with hardware impairments. The closed-form expressions of the total uplink (UL) EE and the average harvested energy (HE) are derived by employing a non-linear energy harvesting model and coherent transmission schemes. An optimization problem is formulated to maximize the total uplink EE, in which power control coefficients for APs and UEs, and the large-scale fading decoding vectors are considered. An alternating algorithm based on successive convex approximation (SCA) is proposed to tackle the complexity issue of the non-convex optimization problem. The numerical results show that the proposed algorithm can significantly enhance the total uplink EE comparing with the equal power allocation strategies. Moreover, it is revealed that the hardware impairments on the UEs can be the primary limitation to the total uplink EE in comparison with those on the APs, however, the impact can be effectively mitigated by the proposed algorithm.

Two C1-symmetric heterohelicenes were constructed by nonsymmetrically extending the ortho-fused structures of a C2v-symmetric NBN-embedded phenalene derivative and featured intense luminescence, large Stokes shifts, and successive reversible redox behaviors. Increasing one fused phenyl unit in such a helical structure led to a 10-fold-enhanced dissymmetry factor. Their strong double hydrogen-bond-donating capability makes them distinctly red-shifted in absorption, emission, and CD and CPL spectra upon the addition of fluoride anion.

In this paper, we investigate the content popularity prediction problem in cache-enabled fog radio access networks (F-RANs). In order to predict the content popularity with high accuracy and low complexity, we propose a Gaussian process based regressor to model the content request pattern. Firstly, the relationship between content features and popularity is captured by our proposed model. Then, we utilize Bayesian learning to train the model parameters, which is robust to overfitting. However, Bayesian methods are usually unable to find a closed-form expression of the posterior distribution. To tackle this issue, we apply a stochastic variance reduced gradient Hamiltonian Monte Carlo (SVRG-HMC) method to approximate the posterior distribution. To utilize the computing resource of fog access points (F-APs) and also reduce the communication overhead, we propose a quantized federated learning (FL) framework combining with Bayesian learning. The proposed quantized federated Bayesian learning framework allows each F-AP to send gradients to the cloud server after quantizing and encoding. It can achieve a tradeoff between prediction accuracy and communication overhead effectively. Simulation results show that the performance of our proposed policy outperforms the considered baseline policies.

[Display omitted] Effects of HY addition on NiMoS active phase of NiMo(NH 3) impregnated NiMo/Al 2 O 3 -HY and its role in 4,6-dimethyl-dibenzothiophene hydrodesulfurization was investigated. The results show that HY can promote HDS reaction by changing the morphology of NiMoS nanoclusters even when isomerization of 4,6-DMDBT is not involved. In the absence of strong acid sites, TOF of NiMo/Al 2 O 3 catalyst was still improved by 90%. XRD, H 2 -TPR, Raman, TEM, and XPS characterization show that proper metal support interaction caused by HY addition is beneficial to the formation of large-scale multilayer NiNoS clusters, the enrichment of Ni in NiMoS clusters and the increase of NiMoS active sites, thereby leading HDS catalyst exhibiting highest intrinsic activity (TOF). However, too strong or too weak metal support interaction will reduce intrinsic activity for HDS catalysts. When pH value of impregnation solution is 10, the strong metal support interaction reduces layer numbers of NiMoS clusters. When pH value of impregnation solution is 11, negative charge hinders the formation of NiMoS clusters. This not only leads to a further decrease HYD pathway selectivity, but also significantly reduces the initial reaction rate of HDS catalyst. [ABSTRACT FROM AUTHOR]

Deep learning has been increasingly recognized as a promising tool in solving kinds of physical problems beyond powerful approximations. A multi-domain physics-informed neural network (mPINN) is proposed to solve the non-uniform heat conduction and conjugate natural convection with the discontinuity of temperature gradient on the interface. Local radial basis function method (LRBF) is applied to compute the case without the analytical solution and is regarded as the benchmark solver. Each physical domain matches a private neural network and all neural networks are connected by the shared information of temperature and heat flux on the interface. Joint training and separate training are utilized to minimize the loss function, which usually consists of the residual of boundary conditions, interface conditions and governing equations. Joint training minimizes the sum of all losses from neural networks with one shared optimizer, while separate training owns its private optimizer. Local adaptive activation function (LAAF) is used to accelerate the convergence and acquire a lower loss value when compared with its fixed counterpart. The numerical experiments on three types of residual points, uniform, Gauss-Lobatto and random, are conducted and it can be concluded that the uniform residual points can obtain the most accurate solution than the random and Gauss-Lobatto. Joint training is more accurate than the separate training when the number of residual points is relatively small, while the separate training performs better than the joint training for the large number of residual points. Numerous test cases on multi-domain heat transfer and fluid flow show the accuracy of the proposed mPINN. Local and global heat transfer rates show good agreements with the results from LRBF. Excepting the forward problems, the thermal conductivity ratio, the constant source and the characteristic parameters of natural convection are accurately learned from sparsely distributed data points.

In recent years, in order to achieve higher performance, the number of design variables used in the aerodynamic optimization of turbomachinery (based on surrogate models) has increased significantly. However, the increase in the design dimensions brings the problems of sparse distribution of training samples and numerous inaccurate local optima to the surrogate model, making it difficult to obtain an accurate Pareto front in high-dimensional aerodynamic optimization. To solve this, adaptive batch sampling strategy (ABSS) is proposed in this paper. By searching numerous local optimum points with large prediction errors in the surrogate model, ABSS can provide batches of valuable samples for each iterative update of the model. Compared with the current model update strategy based on the best point, which requires hundreds or thousands of iterative model updates, ABSS only needs to go through a few model updates to make the predicted Pareto front close to the real one. ABSS not only greatly shortens the whole optimization time, but also makes it easier to jump out of the local optima for the optimization. Based on this, a 114-dimensional aerodynamic optimization of the full three-dimensional centrifugal impeller (including arbitrary blade surfaces, independent splitter surfaces, and non-axisymmetric hub surfaces) is carried out. The results show that, compared with the baseline impeller, the design point isentropic stage efficiency of the optimal impeller is increased by 2.1%, the design point pressure ratio is well controlled to 1.84, and the choke margin is increased by 9.2%. This research breaks through the largest number of variables in the current centrifugal impeller optimization, proposes the optimization methods of the full-3D centrifugal impeller, and also provides a reference for the future high-dimensional aerodynamic optimization of turbomachinery.

Supercharged proteins exhibit high solubility and other desirable properties, but no engineered superpositively charged enzymes have previously been made. Superpositively charged variants of proteins such as green fluorescent protein have been efficiently encapsulated within Archaeoglobus fulgidusthermophilic ferritin (AfFtn). Encapsulation by supramolecular ferritin can yield systems with a variety of sequestered cargo. To advance applications in enzymology and green chemistry, we sought a general method for supercharging an enzyme that retains activity and is compatible with AfFtn encapsulation. The zinc metalloenzyme human carbonic anhydrase II (hCAII) is an attractive encapsulation target based on its hydrolytic activity and physiologic conversion of carbon dioxide to bicarbonate. A computationally designed variant of hCAII contains positively charged residues substituted at 19 sites on the protein’s surface, resulting in a shift of the putative net charge from −1 to +21. This designed hCAII(+21) exhibits encapsulation within AfFtn without the need for fusion partners or additional reagents. The hCAII(+21) variant retains esterase activity comparable to the wild type and spontaneously templates the assembly of AfFtn 24mers around itself. The AfFtn–hCAII(+21) host–guest complex exhibits both greater activity and thermal stability when compared to hCAII(+21). Upon immobilization on a solid support, AfFtn–hCAII(+21) retains enzymatic activity and exhibits an enhancement of activity at elevated temperatures.

Ce- or La-doped Cu/SSZ-13 catalysts were prepared by a hydrothermal method and Cu, Ce or La ions were incorporated through stepwise ion exchange. The catalyst activity was measured for the ammonia selective catalytic reduction reaction. The structure and composition of catalyst were characterized by using X-ray diffraction, scanning electron microscopy, inductively coupled plasma mass spectrometry solid-state NMR, NH3-TPD techniques, and the active components were examined by XPS and XANES. The results indicate that the Ce and La doping can both completely preserve the SCR activity of Cu/SSZ-13 above 300 °C, but there is also a decrease of activity below 200 °C. On the other hand, Ce doping is beneficial to the formation of framework aluminum, stabilizes molecular sieve framework and Cu active sites of Cu/SSZ-13, thereby improves the catalyst hydrothermal stability. But La doping will decrease the amount of framework aluminum and Cu active sites of Cu/SSZ-13 after hydrothermally aging, even destroy zeolite CHA structure. This is quite harmful to the catalyst hydrothermal stability.

A fast radiative rate, highly suppressed nonradiation, and a short exciton lifetime are key elements for achieving efficient thermally activated delayed fluorescence (TADF) organic light-emitting diodes (OLEDs) with reduced efficiency roll-off at a high current density. Herein, four representative TADF emitters are designed and synthesized based on the combination of benzophenone (BP) or 3-benzoylpyridine (BPy3) acceptors, with dendritic 3,3″,6,6″-tetra-tert-butyl-9′H-9,3′:6′,9″-tercarbazole (CDTC) or 10H-spiro(acridine-9,9′-thioxanthene) (TXDMAc) donors, respectively. Density functional theory simulation and X-ray diffraction analysis validated the formation of CH···N intramolecular hydrogen bonds regarding the BPy3-CDTC and BPy3-TXDMAc compounds. Notably, the construction of intramolecular hydrogen bonding within TADF emitters significantly enhances the intramolecular charge transfer (ICT) strength while reducing the donor–acceptor (D-A) dihedral angle, resulting in accelerated radiative and suppressed nonradiative processes. With short TADF exciton lifetimes (τTADF) and high photoluminescence quantum yields (ϕPL), OLEDs employing BPy3-CDTC and BPy3-TXDMAc dopants realized maximum external quantum efficiencies (EQEs) up to 18.9 and 25.6%, respectively. Moreover, the nondoped device based on BPy3-TXDMAc exhibited a maximum EQE of 18.7%, accompanied by an extremely small efficiency loss of only 4.1% at the luminance of 1000 cd m–2. In particular, the operational lifetime of the sky-blue BPy3-CDTC-based device was greatly extended by 10 times in contrast to the BP-CDTC-based counterpart, verifying the idea that the in-built intramolecular hydrogen bonding strategy was promising for the realization of efficient and stable TADF-OLEDs.

To investigate the effect of solid-state co-fermentation on the structural characteristics and bioactivities of polysaccharides in the medicinal residues of Gastrodia Ganoderma(RGG), two kinds of polysaccharides were isolated and purified from unfermented RGG and fermented RGG, named RP and FRP, respectively. The results showed that molecular weight of FRP decreased than RP and its monosaccharide composition changed significantly. RP was mainly composed of Glucose (66.46%) and Galactose (22.83%) while the main monosaccharide components of FRP was galacturonic acid (65.67%). Fermentation caused the surface morphology of FRP to become fragmented and loose, and increased its in vitro antioxidant activity. Both RP and FRP could repair cell damage, reduce the secretion of reactive oxygen species, and protect RAW 264.7 cells from LPS-induced inflammation. Molecular docking results indicated that monosaccharide structures in FRP had stronger binding energy for inflammatory markers. This study may provide theoretical reference for the high-value utilization of Chinese herbal residues.

An organic compound exhibiting simultaneously reversible switch between its emission colors and luminescence mechanisms, possessing high contrast from deep blue normal fluorescence (NF) to yellow thermally activated delayed fluorescence (TADF), is reported. Based on these two complementary colors, white-light emission combining NF and TADF from a single compound can be achieved in various states. Experimental results and density functional theory calculations indicate that the controllable conformational distribution under thermal and mechanical activation is the mechanism responsible for the reversible switching behavior.

The vaned-diffuser usually brings compressor instability problems under the small flow rate, for instance the spike-type rotating stall phenomenon which restricts the operation range and may cause the trouble of blade fatigue. Since it is difficult to mathematically predict the spike-type stall for its randomness, finding out a practical method to warning this stall precursor appears to be meaningful. The paper explains the relationship between the spike-type precursor and the blade passing irregularity coefficient to analyze whether this coefficient is appropriate for the spike-stall warning inside a centrifugal compressor with the vaned-diffuser. The advanced wireless measurements were conducted on a 1.5 stages test centrifugal compressor to capture the unsteady behavior progressing from the design to stall inception within the region between the impeller trailing edge (TE) and diffuser leading edge (LE). The circumferential distribution of the blade passing irregularity has been quantitatively revealed. The steep increase of the blade passing irregularity at some “special locations”, which is responsible for the onset of the spike-type precursor, is highlighted. Also, to further understand the spike precursor inside the diffuser passage corresponding to the circumferential “special location” with maximum irregularity, the high-response transient measurement within this passage is presented. With the help of full-annulus computational fluid dynamics (CFD) simulation and the mathematical model, it is proved that the blade passing irregularity precisely reflects the flow characteristics during the spike precursor, which presents the guidance for this stall warning method.

Recently, a new route to achieve 100% internal quantum efficiency white organic light‐emitting diodes (WOLEDs) was proposed by utilizing noble‐metal‐free thermally activated delayed fluorescence (TADF) emitters due to the radiative contributions by effective reverse intersystem crossing. However, a systematic understanding of their reliability and internal degradation mechanisms is still deficient. Here, we demonstrate high performance and operational stable purely organic fluorescent WOLEDs consisting of a TADF assistant host via a strategic exciton management by multi interlayers. By introducing such interlayers, carrier recombination zone could be controlled to suppress the generally unavoidable quenching of long‐range triplet excitons, successfully achieving remarkable external quantum efficiency of 15.1%, maximum power efficiency of 48.9 lm W−1and LT50 lifetime towards ~2000 h. Our findings also indicate that broadening the carrier recombination region as well as restraining exciplex quenching at carrier blocking interface make significant roles on reduced efficiency roll‐off and enhanced operational lifetime.

Environmental contextOrganic compounds generally make a large contribution to ambient aerosol fine particles, and can influence atmospheric chemistry. Solvent extraction before mass spectrometry is widely used for the determination of organic compounds in aerosols, but the molecular selectivity of different solvents is unclear. We extracted an aerosol sample with various solvents and show how the organic compound profile obtained by mass spectrometry changes depending on the extracting solvent. AbstractFor a comprehensive characterisation of organic compounds in aerosols, samples collected on a hazy day from Beijing were sequentially extracted with various solvents and analysed by Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Electrospray ionisation (ESI) was used for the MS analysis. Aerosol samples were extracted in an apolar-to-polar solvent order of n-hexane (n-C6), dichloromethane (DCM), acetonitrile (ACN) and water, and also extracted in reverse sequence. The separated fractions were defined as non-polar, low-polarity, mid-polarity and high-polarity organic compounds respectively. Approximately 70% of the total organic carbon (TOC) was extractable, of which the water-soluble organic carbon (WSOC) and non-polar organic carbon accounted for 30 and 25% of the TOC respectively. Non-polar and low-polarity compounds with a high degree of molecular condensation such as oxidised polycyclic aromatic hydrocarbons (PAHs) and nitrogen-containing compounds (CHN) were extracted by n-C6 and DCM. Water-soluble organic matter (WSOM) was predominant with aliphatic and aromatic organosulfates (CHOS) and nitrooxy-organosulfates (CHONS). Most oxygen-containing compounds (CHO) and oxygen- and nitrogen-containing compounds (CHON) with high double-bond equivalents (DBEs) and long carbon chains tended to be extracted into organic solvents.

This study investigates the problem of constructing binary descriptor and develops a novel binary descriptor called simple tri-bit binary descriptor (STBD) based on a simple sampling pattern (SSP) and a tri-value binarisation strategy (TBS). First, an SSP is proposed, in which sample points are divided into two groups according to the distance from the pattern centre and smoothed by different circular filters. Then, to make the descriptor adaptive to the matched images, a selection strategy which directly employs detected keypoints as training data is introduced to select 256 point pairs with low correlation from initial pairs. Finally, a modified TBS method is presented to properly refine intensity comparison results. Experiments show that the proposed STBD can perform well and is robust to various transformations, except for scale change.

To get an insight into the occurrence and the mechanism of flow unsteadiness in the tip region of centrifugal compressor impellers, the flow in Krain’s impeller is investigated by using both steady and unsteady RANS solver techniques. It is found that the flow unsteadiness on the pressure side is much stronger than that on the suction side. The periodical frequency of the unsteady flow is around half of the blade passing frequency. The originating mechanism of the flow unsteadiness is illustrated with the time-dependent tip leakage flow and blade loading at the tip region. Due to the blockage caused by the joint effects of broken-downed tip leakage vortex, separated fluids and tip leakage flow at downstream, a low pressure region is formed on the pressure side, consequently the blade loadings is altered. In turn, the changed blade loadings will alter the intensity of tip leakage flow. Such alternative behavior finally results in the periodic process. By comparing the calculated flow field in the cases of single-passage and four-passage models, it is confirmed that the investigated flow unsteadiness is confined in each single passage, as no phase differences are found in the model of four passages. This is different from the situation in axial compressor when the rotating instability is encountered. The flow unsteadiness only occurs at the working conditions with small mass flow rates, and the oscillation intensity will be enhanced with the decrease of mass flow rate. When the mass flow rate is too small, the flow unsteadiness in a single passage may trigger rotating stall, as the disturbance propagates in the circumferential direction.

Image distortions and repetitive patterns widely exist in real images, which results in that feature matching is still a challenging problem though great progress has been made recently. This study presents a matching method, called guidance-constraints method (GCM), which has obvious advantages in resolving problems of matching features on images with image distortions or repetitive patterns. In GCM, feature points are paired and connection compatibility is introduced to describe the relative geometric relations among features, and then potential matches are found by using the defined geometric guidance and are verified by using the defined geometric constraints. Experimental evaluation shows that the proposed GCM can significantly improve both the number of correct matches and correct ratio under various image transformations, especially more effective on images with distortions or containing repetitive patterns.

Thioxanthone derivatives consisting of undecorated carbazole as an electron donor and thioxanthone (TXO) or 9H-thioxanthen-9-one-S,S-dioxide (SOXO) as an electron acceptor in a donor–acceptor (D–A) or donor–acceptor–donor (D–A–D) structure were developed as thermally activated delayed fluorescence emitters to fabricate highly efficient fluorescent organic light emitting diodes. Their emission color was successfully tuned from blue to yellow by changing the sulfur atom valence state of the thioxanthone unit to tune intramolecular charge transfer effect. Their thermal, electrochemical, photophysical, and electroluminescent properties, and theoretical calculations were systematically investigated to illustrate the molecular structure and property relationships. Maximum external quantum efficiency (EQE) of 13.6% with Commission Internationale de L’Eclairage coordinates of (0.37, 0.57) was achieved for green light emission CzSOXO consisting of SOXO and carbazole in a D–A structure. Blue light emission CzTXO and DCzTXO consisting of TXO and carbazole in a D–A and D–A–D structure could also give EQE values exceeding 11%. Their efficiency roll-off with increasing current density was simulated by adopting triplet–triplet annihilation model, indicating that the TXO derivatives suffer more severe efficiency roll-off because of their relatively long delayed fluorescence lifetime (τD).

Developing efficient and color-saturated deep-blue emitting molecules with small Commission Internationale de L’Eclairage (CIE) yvalues is challenging and has great potential for wide-color gamut displays. Herein, we introduce an intramolecular locking strategy to restrain molecular stretching vibrations of the emission spectral broadening. By cyclizing rigid fluorenes and connecting electron-donating groups to the indolo[3,2,1-jk]-indolo[1′,2′,3′:1,7]indolo[2,3-b]carbazole (DIDCz) framework, the in-plane swing of peripheral bonds and stretching vibrations of the indolocarbazole skeleton are restricted due to an increased steric hindrance from cyclized groups and diphenylamine auxochromophores. As a result, reorganization energies at the high-frequency region (1300–1800 cm–1) are reduced, realizing pure blue emission with a small full-width-at-half-maximum (FWHM) of 30 nm by suppressing shoulder peaks of polycyclic aromatic hydrocarbon (PAH) frameworks. The fabricated bottom-emitting organic light-emitting diode (OLED) exhibits an efficient external quantum efficiency (EQE) of 7.34% and deep-blue coordinates of (0.140, 0.105) at a high brightness of 1000 cd/m2. The FWHM of the electroluminescent spectrum is only 32 nm, which is one of the narrowest electroluminescent emissions among the reported intramolecular charge transfer fluophosphors. Our current findings provide a new molecular design strategy to conceive efficient and narrowband emitters with small reorganization energies.

This paper gives a definition of the industrial internet and expounds on the academic connotation of the future industrial internet. From this foundation, we outline the development and current status of the industrial internet in China and globally. Moreover, we detail the avant-garde paradigms encompassed within the National Natural Science Foundation of China (NSFC)’s “Future Industrial Internet Fundamental Theory and Key Technologies” research plan and its corresponding management strategies. This research initiative endeavors to enhance interdisciplinary collaborations, aiming for a synergistic alignment of industry, academia, research, and practical implementations. The primary focus of the research plan is on the pivotal scientific challenges inherent to the future industrial internet. It is poised to traverse the “first mile”, encompassing foundational research and pioneering innovations specific to the industrial internet, and seamlessly bridges to the “last mile”, ensuring the effective commercialization of scientific and technological breakthroughs into tangible industrial market applications. The anticipated contributions from this initiative are projected to solidify both the theoretical and practical scaffolding essential for the cultivation of a globally competitive industrial internet infrastructure in China.

On the basis of feature points pairing, a scale-invariant feature matching method is proposed in this study. The distance between two features is used to compute feature pairs' support region size, which is different from the methods using detectors to provide information to find the support region. Moreover, to achieve rotation invariance, a sub-region division method based on intensity order is introduced. For comparison to the popular descriptors scale-invariant feature transform and speeded-up robust features, the authors also choose the detected points by difference of Gaussian and fast Hessain detectors as feature points to start the authors' method. Additional experiments compare the reported method with similar proposed methods, such as Tell's and Fan's. The experimental results show that the authors' proposed descriptor outperforms the popular descriptors under various image transformations, especially on images with scale and viewpoint transformations.

A computer three-dimensional (3D) vision-aided performance prediction framework for turbomachinery is established in this paper, to improve the accuracy and generalization ability of the artificial neural network (ANN) model under inputs of more than 90 control parameters. In this framework, a RandLA-encoder is built to extract the flow information related to performance and geometric parameters from point cloud data of flow fields inside impellers. By implicitly learning this kind of flow information, the prediction error of the ANN model is reduced by 20–30% compared with the traditional one. Based on this, a full-3D optimization with 91 variables, including arbitrary blade surface and non-axisymmetric (but periodic) hub surface, is conducted on Krain low-speed impeller, aiming at a comprehensive performance improvement. After the optimization, compared to the baseline, the maximum isentropic efficiency of the compressor is increased by 1.6%, the isentropic efficiency at design point is increased by 1%, and the flow range is increased by 5%, with a slight increase in pressure ratio.

A numerical investigation on the aerodynamic effects of impeller-diffuser axial misalignment in the low-flow-coefficient centrifugal compressor is conducted through three-dimensional CFD analysis. The results show that the flow, especially near the diffuser inlet, is influenced by the axial misalignment obviously. When the impeller offsets to one side, the pressure at diffuser inlet close to this side will descend, and the vortex in the cavity on the other side will partially enter the diffuser and then result in the back flow. The performances of the stage and its components also change with the impeller-diffuser axial misalignment. There exists an optimum offset making the efficiency maximum at a given operating point. Furthermore, the effect of impeller-diffuser axial misalignment on the axial thrust is pronounced. The axial thrust is nearly increased linearly with the increase of axial misalignment. The aerodynamic effects of impeller-diffuser axial misalignment in the low-flow-coefficient centrifugal compressor behaves more remarkably at the large flow rate. To alleviate the aerodynamic effects of impeller-diffuser misalignment, a rounding in the meridional plane at the diffuser inlet can be applied.

Stereotactic radiosurgery (SRS) has been an effective treatment method for brain tumors; however, few data are available regarding radiation-induced white matter (WM) damage by SRS. In this work, diffusion tensor imaging (DTI) was used to investigate WM changes following SRS. Fifteen patients with gliomas were enrolled, with prescription doses ranging 18–25 Gy. Patients were scanned with magnetic resonance imaging (MRI) including DTI before and after SRS. Diffusion tensors were calculated and fiber tracking was performed. Non-irradiated WM volumes and irradiated WM volumes receiving =12 Gy and =5 Gy were contoured as volumes of interest (VOI). Apparent diffusion coefficient (), fractional anisotropy (FA) and number of fibers (NF) were calculated and assessed using the Wilcoxon signed-rank test. Compared with those of non-irradiated VOIs, FA and NF decreased considerably after two months of SRS in the irradiated WM VOIs. The variation in was however small and was not statistically significant. The preliminary results suggested that FA and NF might potentially be more sensitive indicators than in measuring radiation-induced WM changes and DTI could be a valuable tool to assess radiation-induced WM changes in SRS. Although it is still preliminary, this pilot study may be useful to provide insights for future studies.

Abstract: The low flow coefficient centrifugal impeller (LFCCI) gives a relatively low efficiency and a special treatment is required for the design of this kind of impeller. This paper investigates the influences of cavity leakage on the performance prediction and design of LFCCI based on Computational Fluid Dynamics (CFD) techniques. The results show that, the reduction in the efficiency of impeller due to the introduction of cavity leakage varies with the blade shape of impeller in a wide range since there is a strong and complex interaction of main flow and leakage flow in the LFCCI. To get a credible optimization result, the backside and foreside cavities should be considered in the CFD-based design of LFCCI.

This report describes the technique and initial experience using cone beam CT (CBCT) for localization of treatment targets in patients undergoing stereotactic body radiation therapy (SBRT). Patients selected for SBRT underwent 3-D or 4-D CT scans in a customized immobilization cradle. GTV, CTV, ITV, and PTV were defined. Intensity-modulated radiation beams, multiple 3-D conformal beams, or dynamic conformal arcs were delivered using a Varian 21EX with 120-leaf MLC. CBCT images were obtained prior to each fraction, and registered to the planning CT by using soft tissue and bony structures to assure accurate isocenter localization. Patients were repositioned for treatment based on the CBCT images. Radiographic images (kV, MV, or CBCT) were taken before and after beam delivery to further assess set-up accuracy. Ten patients with lung, liver, and spine lesions received 29 fractions of treatment using this technique. The prescription doses ranged 1250 ~ 6000 cGy in 1 ~ 5 fractions. Compared to traditional 2-D matching using bony structures, CBCT corrects target deviation from 1 mm to 15 mm, with an average of 5 mm. Comparison of pre-treatment to post-treatment radiographic images demonstrated an average 2 mm deviation (ranging from 0–4 mm). Improved immobilization may enhance positioning accuracy. Typical total “in-room” times for the patients are approximately 1 hour. CBCT-guided SBRT is feasible and enhances setup accuracy using 3-D anatomical information.

Guided-mode resonances in subwavelength gratings are strongly dependent on incident angles. A beam selector with high sensitivity is designed based on this property. A guided-mode resonant silicon nitride (Si3N4)grating on a silicon dioxide (SiO2)substrate is presented as an example of such a device with a 1.55 m wavelength. The calculated reflection resonance has an incident angle FWHM of ∼0.0042radians, and a normal-incident peak efficiency of ∼99.9. In addition, we propose that this type of beam selector be applied to select transverse modes of semiconductor lasers. © 2002 Society of Photo-Optical Instrumentation Engineers.

A new kind of polarizing beamsplitters (PBSs) based on the effects of a birefringent and resonance anomaly is presented. Its properties are analyzed using the correct Fourier modal method and the reflective and transmissive coefficient matrix (RTCM) recursion method. Two examples, one for the IR and the other for the visible, are given. An extremely high polarization extinction ratio is obtained in transmitting space. The effects of small variations in the parameters of the PBSs performance are also investigated. © 2002 Society of Photo-Optical Instrumentation Engineers.