Search

This article studies on the influence of different thermal interface materials (TIMs) on the thermal coupling among devices inside the semiconductor power modules. In particular, an insulated-gate bipolar transistor (IGBT) power module equipped with free-wheeling fast recovery diodes (FRDs) is investigated with two types of TIMs, namely the thermal grease and graphite sheet. The theoretical analysis of thermal coupling among the chips inside the power module is carried out, which is followed by the numerical simulation and experimental test results. The agreement among the results verifies that lower thermal conductivity of the TIMs leads to stronger thermal coupling among chips. As both the self-heating and coupling thermal impedances are dependent on the TIM thermal conductivity, the variation of their contribution ratio to the total thermal resistance is quantified. The influence of TIMs on the mutual coupling between the IGBT and FRD chips is also characterized.

Improving the thermoelectric performance and service stability is essential for the effective use of cuprous selenide (Cu2–xSe). In this study, hexagonal boron nitride (h-BN) was incorporated into nano-Cu2–xSe, with the goal of enhancing thermoelectric performance and service stability. It was found that Cu2–xSe-0.005 wt % BN showed a higher thermoelectric figure of merit (zT)value (∼1.76 at 923 K), which was 11% greater than that of pure Cu2–xSe, mainly due to a significant reduction in lattice thermal conductivity (kL) to about 50% (0.13 W m–1K–1). Additionally, the formation of an ion-blocking interface by hexagonal boron nitride effectively shortens the migration path of Cu+ions, improving service stability while maintaining the contribution of Cu+transitions to thermal conductivity. Finally, an increase in hardness of ∼11.1% was observed, reaching 0.7 GPa in Cu2–xSe-0.02 wt % BN. This research is a feasible approach to improving the service stability of Cu2–xSe.

This article addresses the problem of fixed-time bipartite synchronization (FxTBS) of signed networks (SNs) affected by impulses. First, this article constructs a model of SNs that captures the multilayer properties of the network and takes into account the influence of nonlinear coupling strengths between nodes. To overcome the challenges brought by the introduction of nonlinear coupling strengths, this article adopts a Takagi–Sugeno fuzzy model to characterize the nonlinear variation of coupling strengths reasonably. Then, in the framework of average impulsive interval applicable to a wider range of impulsive signals, this article proposes a novel method for analyzing the fixed-time stability of impulsive systems, which not only loosens the restriction of the derivative of the Lyapunov function in the existing studies, but also gives a more accurate estimation of the settling time, and more importantly, provides a theoretical basis for designing appropriate impulsive signals to modulate the dynamic behavior of SNs toward achieving the desired goal. Based on the newly suggested method, this article derives a unified synchronization criterion suitable for evaluating the implementation of FxTBS of SNs under both desynchronizing and synchronizing impulses. Finally, this article visualizes the correctness of the aforementioned theoretical results utilizing a widely used numerical example.

This article develops a methodology employing partial differential equations (PDEs) to facilitate the exponential deployment of large-scale heterogeneous nonlinear multiagent systems (MASs). The considered MASs comprise a multitude of nonlinear first-order agents (FOAs) and second-order agents (SOAs). Two heterogeneous nonlinear PDEs are established to model the considered MASs by designing appropriate network communication protocols. Unlike previous PDE-based approaches for multiagent deployment, the topological weights between neighboring agents are defined as series-dependent. An informed agent, which is able to measure the location information of other agents and transmit its location information to neighboring agents through the communication network, is placed between the final FOA and the initial SOA. This novel network-based control scheme is referred to as single-point control, which could ensure the well-posedness and exponential stability of the error system. Accordingly, pointwise and distributed measurements are employed for delay-free and time-delayed cases, respectively. Numerical examples are provided in 3-D space to substantiate the obtained theoretical results.

Multichips paralleled insulated gate bipolar transistor (IGBT) power modules are widely employed in industrial and automotive power conversion systems. The asymmetry of the circuit topology and the differences in chip characteristics are the main reasons for the unbalanced current distribution among parallel chips, leading to excessive electrical stress in power modules, which in turn forces the power modules to operate at a reduced rated current. Additionally, the unbalanced current distribution inevitably results in different chip losses, which are further amplified under high current loading conditions, causing some chips to be overheated, and significantly reducing the reliability. Optimizing the circuit topology is a common method to improve current distribution, but global changes often entail higher costs and longer development cycles. Moreover, the electrical parasitic of the fast recovery diodes (FRD) chip branches are not given sufficient attention in circuit topology research. Under rectification and blocked conditions in electric vehicles, FRDs often become the bottleneck for lifespan due to excessively high junction temperatures. Therefore, this article conducts a comparative analysis of the circuit parasitic in IGBT and FRD loops with several typical layouts, without changing the substrate and chip dimensions, and proposes a current sharing slot structure design to balance the parasitic parameters. Compared with the direct bonded copper (DBC) layout of the typical EconoDUAL power module, the optimized module reduces the current imbalance of FRD from 45.5% to 11.6% and the switching loss can be reduced by 8.6%. By adopting the current sharing groove, the parasitic parameter distribution can be further improved while maintaining a fixed DBC layout, considering the IGBT and FRD branches in concert. Finally, the steady-state and transient current sharing characteristics were verified under constant current and inverter conditions. Under constant current conditions, the temperature difference of FRD in the upper and lower parallel layout modules was reduced by 16.7 °C, and the junction temperature of IGBT was significantly lowered. Under inverter conditions, the highest junction temperature of the columnar layout modules could be reduced by 10 °C, and the temperature difference of FRD decreased by 62%. This article significantly optimizes the current imbalance issue through layout design, reduces the thermal equilibrium difference of the module under application conditions, and is conducive to improving the output capacity and fatigue life of the module, providing a solution for the design of power modules with high junction temperature operation capability and high-reliability.

Much palaeontology research on biomineralization has been directed to studying the Cambrian radiation of biomineralizing animals. The evolutionary radiation of biomineralization in the Cambrian Period was preceded by weakly biomineralized animals in the late Ediacaran period around 550–539 Ma. Here we report many new tubular fossils from the upper part of the Ediacaran Dengying Formation in the Lijiagou section, Ningqiang area, southern Shaanxi Province, China, consisting of two new genera and species, namely Shufangtubulus inornatusn. gen. n. sp., and Palaeorhopalon spiniferumn. gen. n. sp. The newly discovered materials expand the list of the Ediacaran tubular fossils. The borings first found on the outer surface of Sinotubulites baimatuoensisare similar to those of Cloudina, which may reveal the earliest predator-prey dynamics. The small and delicate drill holes detected on the inner walls of Sinotubulites baimatuoensisare inferred to be infested traces by parasitism.

Herein, a direct transformation of aliphatic C–H bonds to oxime ethers has been developed via light-promoted hydrogen atom transfer (HAT) in the absence of a photocatalyst. Singlet oxygen and chlorine radical are complementary C(sp3)–H bond cleaving agents in this reaction, enabling the extraction of hydrogen atoms from a diverse range of compounds, like cycloalkanes, ethers, amines, amides, and cyclic sulfides. This method excels in transforming common aliphatic C–H bonds into valuable oxime ethers featuring abundant chemical feedstocks, good functional group tolerance, and catalyst free conditions.

A direct and novel transformation of propargylic alcohols with sodium sulfinates for the regio- and stereoselective synthesis of (E)-1,3-disulfonylpropenes and (E)-1-sulfonylpropenols was successfully developed in the presence of TMSCl under mild conditions. The preliminary mechanistic experiments demonstrated that the reaction underwent an unprecedented dual nucleophilic substitution/radical addition process, in which sodium sulfinates were used not only as nucleophiles but also as a sulfonyl radical source.

The impairment of blood-brain barrier (BBB) integrity is the pathological basis of hemorrhage transformation and vasogenic edema following thrombolysis and endovascular therapy. There is no approved drug in the clinic to reduce BBB damage after acute ischemic stroke (AIS). Glial growth factor 2 (GGF2), a recombinant version of neuregulin-1β that can stimulates glial cell proliferation and differentiation, has been shown to alleviate free radical release from activated microglial cells. We previously found that activated microglia and proinflammatory factors could disrupt BBB after AIS. In this study we investigated the effects of GGF2 on AIS-induced BBB damage as well as the underlying mechanisms. Mouse middle cerebral artery occlusion model was established: mice received a 90-min ischemia and 22.5 h reperfusion (I/R), and were treated with GGF2 (2.5, 12.5, 50 ng/kg, i.v.) before the reperfusion. We showed that GGF2 treatment dose-dependently decreased I/R-induced BBB damage detected by Evans blue (EB) and immunoglobulin G (IgG) leakage, and tight junction protein occludin degradation. In addition, we found that GGF2 dose-dependently reversed AIS-induced upregulation of vesicular transcytosis increase, caveolin-1 (Cav-1) as well as downregulation of major facilitator superfamily domain containing 2a (Mfsd2a). Moreover, GGF2 decreased I/R-induced upregulation of PDZ and LIM domain protein 5 (Pdlim5), an adaptor protein that played an important role in BBB damage after AIS. In addition, GGF2 significantly alleviated I/R-induced reduction of YAP and TAZ, microglial cell activation and upregulation of inflammatory factors. Together, these results demonstrate that GGF2 treatment alleviates the I/R-compromised integrity of BBB by inhibiting Mfsd2a/Cav-1-mediated transcellular permeability and Pdlim5/YAP/TAZ-mediated paracellular permeability.

Esophageal variceal diameter (EVD) is one of the most important predictors of variceal bleeding, as well as an important predictor of the effectiveness of endoscopic esophageal varices (EV) treatments. EVD is currently determined using visual inspection by endoscopic operators, meaning that results can vary widely between operators. This approach also means that cases unsuitable for endoscopic variceal ligation (EVL) can be complicated by postoperative hemorrhage. Thus, the purpose of this study was to explore the value of a virtual ruler (VR) in predicting rebleeding after the endoscopic treatment of EV in patients with cirrhosis.

An efficient and high-selectivity approach for the divergent synthesis of β-sulfinyl alkenylsulfones and (E)-vinyl sulfones from alkynes and TsCN is described. A series of disulfurized products were constructed under mild conditions in the absence of transition metals. This transformation featured excellent regio- and stereoselectivity, good functional group compatibility, and broad substrate scope. The copper(I)-catalyzed sulfonation of alkynes with TsCN that affords (E)-vinyl sulfones in good to excellent yields was also developed.

Constructing an accurate model with the capability to accurately forecast gas solubility in electrolyte solutions across diverse temperature, pressure, and salt concentration ranges holds significant relevance for carbon capture and storage (CCS). The model was modified by introducing the Debye–Hückel electrostatic term in the previously published CPA-MHV1 equation of state to account for the influence of salt on the gas solubility. The water–salt and gas–salt binary interaction parameters were optimized using experimental data, and the phase behavior of CO2and CH4was investigated in five salt solutions, NaCl, KCl, MgCl2, CaCl2, and Na2SO4. Furthermore, various association schemes for CO2were compared, revealing optimal simulation outcomes when modeling CO2as a nonself-associating molecule solvated in water. The average absolute relative deviation values of CO2and CH4obtained by this method in five single-salt solutions were 7.08 and 3.87%, respectively. The proposed model demonstrates a high degree of accuracy in simulating vapor–liquid equilibrium within water–gas–salt systems.

A novel micro-nano Ti−10Cu−10Ni−8Al−8Nb−4Zr−1.5Hf filler was used to vacuum braze Ti−47Al− 2Nb−2Cr−0.15B alloy at 1160−1220 °C for 30 min. The interfacial microstructure and formation mechanism of TiAl joints and the relationships among brazing temperature, interfacial microstructure and joint strength were emphatically investigated. Results show that the TiAl joints brazed at 1160 and 1180 °C possess three interfacial layers and mainly consist of α2-Ti3Al, τ3-Al3NiTi2and Ti2Ni, but the brazing seams are no longer layered and Ti2Ni is completely replaced by the uniformly distributed τ3-Al3NiTi2at 1200 and 1220 °C due to the destruction of α2-Ti3Al barrier layer. This transformation at 1200 °C obviously improves the tensile strength of the joint and obtains a maximum of 343 MPa. Notably, the outward diffusion of Al atoms from the dissolution of TiAl substrate dominates the microstructure evolution and tensile strength of the TiAl joint at different brazing temperatures.

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by impaired social interactions, communication deficits and repetitive behaviors. A study of autistic human subjects has identified RFWD2as a susceptibility gene for autism, and autistic patients have 3 copies of the RFWD2gene. The role of RFWD2 as an E3 ligase in neuronal functions, and its contribution to the pathophysiology of ASD, remain unknown. We generated RFWD2knockin mice to model the human autistic condition of high gene dosage of RFWD2. We found that heterozygous knockin (Rfwd2+/−) male mice exhibited the core symptoms of autism. Rfwd2+/−male mice showed deficits in social interaction and communication, increased repetitive and anxiety-like behavior, and spatial memory deficits, whereas Rfwd2+/−female mice showed subtle deficits in social communication and spatial memory but were normal in anxiety-like, repetitive, and social behaviors. These autistic-like behaviors in males were accompanied by a reduction in dendritic spine density and abnormal synaptic function on layer II/III pyramidal neurons in the prelimbic area of the medial prefrontal cortex (mPFC), as well as decreased expression of synaptic proteins. Impaired social behaviors in Rfwd2+/−male mice were rescued by the expression of ETV5, one of the major substrates of RFWD2, in the mPFC. These findings indicate an important role of RFWD2 in the pathogenesis of autism.

The role of incommensurate (IC) modulation in the evolution of the pinched polarization–electric field (P–E) hysteresis loops has been investigated and discussed based on the structure and polarization evolution in Ba4(Sm1–xLax)2Ti4Nb6O30tetragonal tungsten bronzes. The relaxor behavior in the La-rich compound is accompanied by an IC modulation structure. Introduction of smaller Sm in the system increases the driving force for the transition from an IC modulation structure to a commensurate superstructure, which coupled with the ferroelectric transition in the middle composition with x= 0.5. In the Sm-rich compounds, the IC modulation structure reappears as a metastable state to balance the structural instability caused by the too small average ionic radius of the rare-earth ion; meanwhile, the field-induced transition from the IC modulation structure to the commensurate superstructure is confirmed by selected area electron diffraction using an in situ bias technique as the structural origin for the pinched P–Eloops. A phase diagram has been established by combining the ferroelectric phase transition and the modulation structure transition, and a new region with both very small A-site size (A1 + A2)/2 and A1-site tolerance factor (tA1) related to the ferroelectric compounds with pinched P–Eloops (pinched FE) was added into the previously reported crystal-chemical framework (Chem. Mater.2015,27,3250–3261). The present work expands the composition–structure–property relationships in tungsten bronze ferroelectrics by including the recently reported “pinched FE” and meanwhile extends the composition manipulation ranges from the crossover between relaxor and normal ferroelectrics to ferroelectrics with pinched P–Eloops.

Particle erosion induced by foreign object damage (FOD) is an important factor that restricts the working life of thermal barrier coatings (TBCs). A dense α-Al2O3overlay was prepared by magnetron sputtering and vacuum treatment on the surface of 7YSZ TBCs sprayed by plasma spray-physical vapor deposition (PS-PVD) to improve the erosion resistance of the TBCs. The FOD behavior of the TBCs was systematically studied and the interface of α-Al2O3/c-ZrO2was investigated by first principles calculations. The experimental results show that the erosion rates of the PS-PVD, atmospheric plasma spraying (APS), and electron beam-physical vapor deposition (EB-PVD) TBCs were 324, 248, and 139 μg/g, respectively, while the erosion rate of the Al2O3-modified PS-PVD TBCs was reduced to 199 μg/g. In addition, the highest interface adhesive energy of 3.88 J/m2observed in the top configuration model of Al2O3/ZrO2−O is much higher than that of ZrO2/Ni (2.011 J/m 2), which results in improved interface bonding performance.

To address the inhomogeneous microstructure and improve the mechanical properties of DT300 ultra-high strength steel specimens fabricated by laser powder bed fusion, different post-heat treatment schedules are performed. With the increase in austenitizing temperature and time, the migration rate of austenite grain boundaries continuously increases with the dissolution of nano-carbides, and the formation of nano-oxides and twin martensite is also inhibited accordingly. The rapid growth in the size of prior austenite grains and martensite laths, as well as the decrease in the content of nano-oxides and twin martensite, led to a rapid decrease in the strength (yield strength and ultimate tensile strength) from HT2 to HTF specimens. The HT1 specimens (austenitizing at 830 °C for 30 min, then oil quenching and tempering at 300 °C for 120 min and finally air cooling) display excellent mechanical properties of yield strength of 1572 MPa, ultimate tensile strength of 1847 MPa, elongation of 9.84%, and fracture toughness of 106 MPa m1/2, which are counterparts to those of conventional DT300 steel forgings after heat treatment.

Tall wheatgrass is a perennial salt‐tolerant bunchgrass, which is a promising candidate for establishing a “Coastal Grass Belt” in China, particularly in the coastal saline–alkaline soils surrounding the Bohai Sea. Seven harvesting treatments were performed to explore the optimal harvesting time and frequency for tall wheatgrass in coastal area. The dry matter yield (DMY) and forage nutritional values were investigated for each cut. The correlation between harvesting time and frequency thereof among the investigated traits was also determined. The results showed that the two‐cut on June 18 and October 29 produced the highest DMY. Another two‐cut on May 26 and October 29 produced a relatively high crude protein (CP) yield. The DMY, contents of neutral detergent fiber (NDF), acid detergent fiber (ADF), and crude cellulose (CC) as well as CP yield were positively correlated to plant height, while the CP content and the relative feed value (RFV) were negatively correlated to plant height. The accumulating growing degree days, accumulated precipitation, and sunshine duration were positively correlated with plant height, DMY, contents of NDF, ADF, and CC as well as CP yield, but negatively correlated with CP content and RFV for the first cut. The two‐cut treatment at the end of May and October may be suitable for tall wheatgrass in the “Coastal Grass Belt” targeted area. The two‐cut system clipped at the end of May and October may be suitable for tall wheatgrass in the “Coastal Grass Belt” targeted area.

Water-stable organic radicals are promising photothermal conversion candidates for photothermal therapy (PTT). However, organic radicals are usually unstable in biological environments, which greatly hinders their wide application. Here, we have developed a chaotropic effect-based and photoinduced water-stable supramolecular radical (MB12-2) for efficient antibacterial PTT. The supramolecular radical precursor MB12-1 was constructed by the chaotropic effect between closo-dodecaborate cluster (B12H122–) and N,N′-dimethylated dipyridinium thiazolo [5,4-d] thiazole (MPT2+). Subsequently, with triethanolamine (TEOA) serving as an electron donor, MB12-1 could transform to its radical form MB12-2 through photoinduced electron transfer (PET) under 435-nm laser irradiation. The N2adsorption–desorption analysis confirmed that MB12-2 was tightly packed through the introduction of B12H122–, which effectively enhanced its stability via a spatial site-blocked effect. Moreover, the half-life of MB12-2 in water was calculated through ultraviolet–visible light (UV-vis) absorption spectra results for periods as long as 20 days. In addition, in the skin infection model, MB12-2, as a wound dressing, showed remarkable photothermal antibacterial activity (>97%) under 660-nm laser irradiation and promoted wound healing. This study presents a simple method for designing long-term water-stable supramolecular radicals, offering a novel avenue for noncontact treatments for bacterial infections.

AbstractIn karst regions, the occurrence of sinkholes is a common cause of roadway failures, leading to significant embankment deformation and instability. The advantages of geosynthetic reinforcement have been proven in practice in numerous countermeasures to lessen the impact of localized sinkholes, and associated design methodologies have been developed. However, some existing design methods assume there is no deformation in geosynthetics embedded in soils, and the effect of matric suction in soils is not considered either. This study suggested an analytical approach that took into account the strain in the geosynthetic reinforcements as well as the impact of matric suction. The developed design method was used to conduct parameter studies under various matric suction conditions. The method was validated against the experimental results, and the feasibility of the developed method was also compared with the existing design methods. The findings demonstrate that, in comparison to the method created here, existing design methodologies produce more conservative results. The strain and the deflection of the geosynthetic calculated using the suggested method are lower than those provided by the current design methodologies.

An iron-catalyzed photochemical sulfinamidation of hydrocarbons with N-sulfinylamines has been developed. The merger of ligand-to-metal charge transfer (LMCT) of FeCl3with hydrogen atom transfer (HAT) process is the key for the generation of alkyl radicals from hydrocarbons, and the resultant alkyl radicals were readily trapped by N-sulfinylamines to produce structurally diverse sulfinamides. Contrary to traditional methods that inevitably use sensitive organometallic reagents and prefunctionalized substrates, our approach features simple operation and the wide availability of starting materials. Gratifyingly, the reaction is scalable, and the obtained sulfinamides can be conveniently converted to highly functionalized sulfur(VI) derivatives.

A novel conversion of 1,5-diynols into sulfonylated benzo[b]fluorenes is reported by a TFA-promoted cascade cyclization with sodium sulfinates under mild conditions. This strategy provides an efficient and practical approach for accessing various sulfonated benzo[b]fluorenes in moderate to excellent yields under metal-free conditions. On the basis of the control experimental results and density functional theory calculations, a possible cascade transformation mechanism consisting of the dehydration of propargylic alcohols, sulfonylation, allenylation, and Schmittel-type cyclization is proposed. It is worth noting that TFA played an important role in this cascade cyclization, which promoted C–SO2R bond cleavage in a propargylic sulfone intermediate to form allenyl sulfones, followed by Schmittel-type cyclization to give the target product.

Endothelium-dependent contraction (EDC) exists in blood vessels of normotensive animals, but is exaggerated in hypertension. An early signal in EDC is cytosolic Ca2+rise in endothelial cells. In this study we investigated the functional role of Orai1, a major endothelial cell Ca2+entry channel, in EDC. Hypertension model was established in WT mice by intake of L-NNA in the drinking water (0.5 g/L) for 4 weeks or osmotic pump delivery of Ang II (1.5 mg·kg−1·d−1) for 2 weeks. In TRPC5 KO mice, the concentration of L-NNA and Ang II were increased to 1 g/L or 2 mg·kg−1·d−1, respectively. Arterial segments were prepared from carotid arteries and aortas, and EDC was elicited by acetylcholine in the presence of Nω-nitro-L-arginine methyl ester. We showed that low concentration of acetylcholine (3–30 nM) initiated relaxation in phenylephrine-precontracted carotid arteries of both normotensive and hypertensive mice, while high concentration of acetylcholine (0.1–2 μM) induced contraction. Application of selective Orai1 inhibitors AnCoA4 (100 μM) or YM58483 (400 nM) had no effect on ACh-induced relaxation but markedly reduced acetylcholine-induced EDC. We found that EDC was increased in hypertensive mice compared with that of normotensive mice, which was associated with increased Orai1 expression in endothelial cells of hypertensive mice. Compared to TRPC5 and TRPV4, which were also involved in EDC, endothelial cell Orai1 had relatively greater contribution to EDC than either TRPC5 or TRPV4 alone. We identified COX-2, followed by PGF2α, PGD2 and PGE2 as the downstream signals of Orai1/TRPC5/TRPV4. In conclusion, Orai1 coordinates together with TRPC5 and TRPV4 in endothelial cells to regulate EDC responses. This study demonstrates a novel function of Orai1 in EDC in both normotensive and hypertensive mice, thus providing a general scheme about the control of EDC by Ca2+-permeable channels.

To optimize the anti-interference performance and dynamic response ability of permanent magnet linear synchronous motor (PMLSM) and enhance the overall control performance of the system, the novel nonsingular fast terminal sliding mode controller (NFTSMC) based on disturbance compensation is proposed in this design. To enhance the response speed and stability of the controller, this design introduces the system state variable into the exponential reaching law to make the controller adaptively adjust with the change of the system state, which can reduce the chattering of the system and have a faster response speed. The extended sliding mode disturbance observer is designed to estimate the interference factors in the system, and the controller is feedforward compensated to further improve the anti-interference ability of the PMLSM system. Meanwhile, the control strategy is proved by the Lyapunov stability theory. Simulation and experiments show that the proposed control strategy has better dynamic response ability and anti-interference ability than the traditional NFTSMC.

A practical synthesis of valuable N-acyl anthranilic acids has been achieved via a silver-catalyzed imino-ketene generation from readily available anthranils and carboxylic acids. A wide range of carboxylic acids including sterically demanding aliphatic carboxylic acids, aromatic carboxylic acids, acrylic acids, and amino acids are compatible in this reaction. Moreover, this method can be used to modify drug molecules and natural products, such as ibuprofen, probenecid, and acetylglycine.

This article considers both the semi-Markov jumping phenomenon and spatial distribution characteristics when investigating the exponential stabilization of memristive neural networks (MNNs). The introduction of the semi-Markov jumping parameters relaxes the restriction on the sojourn time of Markovian MNNs. To increase the operability while ensuring control effect, a novel event-based spatially pointwise-piecewise switching control scheme is presented under a unified spatial division criterion, in which the pointwise and piecewise control can switch according to the preset event condition for the applicability to different control requirements. Moreover, by constructing a semi-Markov Lyapunov functional and utilizing the properties of the considered cumulative distribution function, the final exponential stabilization criterion and two related corollaries are obtained. Finally, simulation results illustrate the effectiveness and superiority of the proposed control strategy.

We propose a programmable topological metasurface to integrate intelligent modulations of spatial and surface waves. A general design method is presented to design the programmable metasurface elements with PIN diodes. The surface waves can be controlled to propagate along the topological domain-wall interface by programming the C3-symmetry elements, while the spatial waves are modulated by the patterns of C6-symmetry elements. By independently controlling the bias voltages of meta-elements, the programmable topological metasurface can generate different coding patterns with distinct combinations of C3- and C6-symmetries in real time, respectively achieving the dynamical manipulation of the surface- and spatial-wave by using distinct element states in a time-division manner. To validate the modulation performance, we perform both near- and far-field tests with different coding patterns. Experimental results demonstrate good agreement with numerical simulations, thereby showcasing the flexible manipulations of surface waves and spatial waves by the topological metasurface. The proposed metasurface opens up new possibilities for multifunctional metadevices, which hold great potentials for future wireless communications and smart sensing systems.

In order to optimize the time-consuming of hierarchical cascade technique (HCT) during finite-length surface acoustic wave (SAW) device simulation, an improved HCT simulation method was proposed. To improve the stability of calculation and accelerate the simulation, the system matrix is preprocessed by combining column scaling and equilibrium pretreatment technology, which can reduce the condition number and meet the single-precision numerical calculation requirement. An improved mirror cascade method was used to decrease the number of basic unit blocks, which can be extended to rotary cascade to reduce the number of cascade operations. A search tree was designed to find the optimal cascade sequence and make the number of cascading operations to be the minimum. The numerical experiments were carried out that the simulation speed of the proposed HCT simulation method for finite-length SAW devices was 30%–80% faster than that of mirror cascade and single-precision HCT method and 2–3 times faster than that of traditional HCT simulation. A Quartz resonator was manufactured to further testify the feasibility of the proposed method. The experimental results showed that the simulated Y11 is close to the measured Y11, while the speed of the proposed HCT method was 2.16 times faster than the traditional HCT. The experimental results verify that the proposed method can accelerate the SAW device simulation process.

Hot deformation behavior of 0.3C–15Cr–1Mo–0.5N high nitrogen martensitic stainless steel (HNMSS) was investigated in the temperature range of 1173–1473 K and at strain rates of 0.001–10 s−1using a Gleeble 3500 thermal–mechanical simulator. The true stress–strain curves of the studied HNMSS were measured and corrected to eliminate the effect of friction on the flow stress. The relationship between the flow stress and Zener–Hollomon parameter for the studied HNMSS was analyzed in the Arrhenius hyperbolic sine constitutive model by the law of Z=3.76×1015sinh0.004979σp7.5022. The processing maps at different strains of the studied HNMSS were plotted, and its flow instability regions in hot working were also confirmed in combination with the microstructure examination. Moreover, the optimal hot deformation parameters of the studied HNMSS could be suggested at T= 1303–1423 K and ε˙= 5–10 s−1or T= 1273–1473 K and ε˙= 0.005–0.04 s−1.

In this article, global exponential stabilization of Takagi–Sugeno (T–S) fuzzy systems with discrete time-varying delays on time scales under denial-of-service (DoS) attacks is investigated. When a DoS attack occurs, the control channel is blocked and the controller is disabled. Combining analytical method, inequality techniques, and time scale theory, stabilization criterion for the underlying systems is obtained via a fuzzy controller. Furthermore, the corresponding outcomes on continuous and discrete time domains are provided, respectively. Finally, two numerical simulations and an application of the Chua's circuit are exhibited to validate the effectiveness of the theories.

In this article, exponential synchronization of complex dynamical networks (CDNs) on time scales is researched. An intermittent dynamic event-triggered control strategy is designed to decrease the number of the event-triggered updating instants. Leveraging intermittent event detections and event-triggered sampling, and combining the analytical method with the time-scale theory, synchronization criteria are obtained for the underlying CDNs. Moreover, a parameter selection algorithm is given to acquire control parameters. In addition, two lemmas on exponential functions of time scales are proposed to prove the exclusion of Zeno behavior. Two numerical simulations and an application of formation control of spacecrafts are given to verify the validity of theoretical results.

Herein, a novel ratiometric sensor for fluorimetric and smartphone-assisted visual detection of Al3+in environmental water was developed based on the target-regulated formation of Eu metal–organic frameworks (Eu MOFs). By employing 2-[4-(2-hydroxyethyl) piperazin-1-yl] ethanesulfonic acid (Hepes), Eu3+and tetracycline (TC) as raw materials, Eu MOFs with red emission were facilely synthesized through the coordination of Eu3+with Hepes and TC. However, upon the introduction of Al3+, a higher affinity of TC towards Al3+resulted in the formation of a TC–Al3+complex with green fluorescence and inhibited the generation of Eu MOFs. This led to an increase in green fluorescence and a decrease in red fluorescence accompanied by the fluorescence color of the solution changing from red to green under the illumination of the UV lamp. Thus, a ratiometric sensor for fluorimetric and the smartphone-assisted visual detection of Al3+was established. The ratiometric sensor exhibited high sensitivity for Al3+detection with a detection limit of 0.14 μM for fluorescence detection and 1.21 μM for visual detection. Additionally, the proposed strategy was successfully applied to detect Al3+in the environmental water samples with satisfactory results, indicating great application prospects for environmental monitoring.

In this work, we proposed a synthesis strategy for a novel drug delivery system (DDS) composed of rod-shaped hollow mesoporous silica core and luminescent Gd2O3:Eu shell. This interesting nanostructure combines the luminescence of Eu3+with the excellent drug carrying capacity of rod-shaped hollow mesoporous silica. The structure and morphology of the DDS were characterized by X-ray difraction, Fourier transform infrared, scanning electron microscopy and Transmission electron microscopy. The prepared DDS possessess rod-shaped core shell structure, in which length of the hollow mesoporous silica nanorods as approximately 400 nm and a width of approximately 150 nm and the Gd2O3:Eu shell was approximately 30 nm thick. The as-prepared DDS emitted bright red light, and the in vitro assays with NCI-H460 lung cancer cells domenstrated that the as-obtained DDS could rapidly and massively enter the cell. In addition, the prepared DDS showed a high loading capacity of IBU (19.4%). As the amount of ibuprofen released increases, the photoluminescence intensity of the DDS increases. Thus, it is possible to monitor and track the release process through changes in luminous intensity. In summary, it is expected that the prepared DDS may be applied in drug carrying, luminescent tracking and monitoring, and optical imaging. Furthermore, this work provides a reliable approach for the design and preparation of the functionalized rod-shaped mesoporous silica.

The return capsule needs to be launched to the moon and return back to earth in the third stage of the Chinese lunar exploration project. Therefore, it is necessary to perform simulations on the ground. This paper presents an 8-cable-driven parallel manipulator to achieve end-force output in a low-gravity environment. End-force output refers to the vector sum of the external force on the end-effector. A model of end-force output is established based on a kinematics model, a dynamic model, and a force analysis of an 8-cable driven parallel manipulator. To obtain end-force output in a low-gravity environment, the cable force has to be controlled to counteract gravity. In addition, a force-position mix control strategy is proposed to proactively control the cable force according to the force optimal distribution given by the closed-form force distribution method. Furthermore, a suitable choice for an end-force output is obtained by modeling the effect of cable force on end-force output. Experimental results show that the actual cable force agrees well with the calculated force distribution, indicating that it is feasible to realize end-force output in a low gravity environment.

Pinless friction stir spot welding (P-FSSW) was performed to manufacture Mg/steel lap joints. Orthogonal tests for P-FSSW of Mg/steel were investigated, and the main factors affecting the properties of Mg/steel lap joints were derived. The shear force of the Mg/steel lap joints gradually increased and then decreased as the welding time increased. Maximum shear force was 5.3 kN. Fe–Al intermetallic compound (IMC) was formed at the Mg/steel interface near the steel side, and Mg–Al IMCs were formed at the Mg/steel interface near the Mg alloy side. Mg/steel lap joint was transformed from an initial solid-state welding to fusion-brazing welding as the welding time increased. No hole defects were formed in Mg/steel solid-state welding joints, whereas hole defects appeared in Mg/steel fusion-brazing welding joints. The temperature field of Mg/steel lap joints was simulated to analyze hole defects generated during the welding process. Hole defects can be eliminated by changing the spindle deflection angle, and the shear force decreased. Excessive spindle deflection can also lead to failure to form a stable joint. Hole defects were removed because the spindle deflection angle reduced the interfacial reaction temperature, and a solid-state welding joint was formed, which resulted in an absence of fusion-brazing welding hole formation.

Stability theory of linear differential–difference system has been well-established, while fewer results can be found for nonlinear differential–difference systems. In this article, stability and boundedness of homogeneous differential–difference system with bounded delay is studied based on the system positivity. At first, an exponential stability criterion is obtained, which is an extension of an existing result. Next, another boundary is computed under the previous condition, which proves to be tighter than the first result at least in some cases. Then, a finite-time stability condition is achieved for the delay-free system, and an upper bound of the settling time and an explicit boundary of the state are derived. Finally, a numerical example is given to verify the results presented in this article.

In this work, a facile fluorescence Eu3+-based metal–organic framework (Eu MOF) sensor for ascorbic acid (AA) and ascorbate oxidase (AAO) detection was developed. The fluorescence of the Eu MOF could be effectively quenched by Ce3+but not by Ce4+at an appropriate concentration, and thus, when the reductant AA was added into the solution containing Ce4+, Ce4+was chemically reduced to Ce3+, which induced the decreased fluorescence signal of the Eu MOF. However, when AAO was introduced, AA was effectively oxidized to dehydroascorbic acid (DHAA) under the catalysis of AAO, and thus, Ce4+could not be reduced, resulting in the fluorescence restoration of the Eu MOF. Hence, the concentration of AA and AAO could be determined by the fluorescence decrease and restoration of the Eu MOF. The fluorescent platform showed high sensitivity with a limit of detection of 0.32 μM for AA and 1.18 U L−1for AAO, respectively. Moreover, the proposed method was successfully applied for AA and AAO determination in real samples, indicating great potential for biomedical application in complex matrices.

Hybrid improper ferroelectricity has been extensively reported through theoretical prediction and experimental investigation in the oxides with Ruddlesden-Popper (R–P) structures. However, the experimentally reported ferroelectric materials based on triple-layer R–P structures are rare, and the weak ferroelectricity impedes its practical application. In the present work, the single-phase Li2Nd2Ti3O10ceramics with A-site cation ordered triple-layer R–P structure was obtained by spark plasma sintering technique, and the crystal structure of P21absymmetry was revealed by neutron powder diffraction and transmission electron microscope analysis. Furthermore, the switchable ferroelectricity in Li2Nd2Ti3O10ceramics has been observed at room temperature, and the saturated polarization-electric field hysteresis loop was obtained with Pr = 0.4 μC/cm2under the electric field of 250 kV/cm. The phase transition behavior of Li2Nd2Ti3O10oxides was revealed by the temperature-dependence Raman and dielectric spectra combined with the piezoelectric property.

SARS-CoV-2 infection causes injuries of not only the lungs but also the heart and endothelial cells in vasculature of multiple organs, and induces systemic inflammation and immune over-reactions, which makes COVID-19 a disease phenome that simultaneously affects multiple systems. Cardiovascular diseases (CVD) are intrinsic risk and causative factors for severe COVID-19 comorbidities and death. The wide-spread infection and reinfection of SARS-CoV-2 variants and the long-COVID may become a new common threat to human health and propose unprecedented impact on the risk factors, pathophysiology, and pharmacology of many diseases including CVD for a long time. COVID-19 has highlighted the urgent demand for precision medicine which needs new knowledge network to innovate disease taxonomy for more precise diagnosis, therapy, and prevention of disease. A deeper understanding of CVD in the setting of COVID-19 phenome requires a paradigm shift from the current phenotypic study that focuses on the virus or individual symptoms to phenomics of COVID-19 that addresses the inter-connectedness of clinical phenotypes, i.e., clinical phenome. Here, we summarize the CVD manifestations in the full clinical spectrum of COVID-19, and the phenome-wide association study of CVD interrelated to COVID-19. We discuss the underlying biology for CVD in the COVID-19 phenome and the concept of precision medicine with new phenomic taxonomy that addresses the overall pathophysiological responses of the body to the SARS-CoV-2 infection. We also briefly discuss the unique taxonomy of disease as Zheng-houpatterns in traditional Chinese medicine, and their potential implications in precision medicine of CVD in the post-COVID-19 era.

Atherosclerotic diseases remain the leading cause of adult mortality and impose heavy burdens on health systems globally. Our previous study found that disturbed flow enhanced YAP activity to provoke endothelial activation and atherosclerosis, and targeting YAP alleviated endothelial inflammation and atherogenesis. Therefore, we established a luciferase reporter assay-based drug screening platform to seek out new YAP inhibitors for anti-atherosclerotic treatment. By screening the FDA-approved drug library, we identified that an anti-psychotic drug thioridazine markedly suppressed YAP activity in human endothelial cells. Thioridazine inhibited disturbed flow-induced endothelial inflammatory response in vivo and in vitro. We verified that the anti-inflammatory effects of thioridazine were mediated by inhibition of YAP. Thioridazine regulated YAP activity via restraining RhoA. Moreover, administration of thioridazine attenuated partial carotid ligation- and western diet-induced atherosclerosis in two mouse models. Overall, this work opens up the possibility of repurposing thioridazine for intervention of atherosclerotic diseases. This study also shed light on the underlying mechanisms that thioridazine inhibited endothelial activation and atherogenesis via repression of RhoA-YAP axis. As a new YAP inhibitor, thioridazine might need further investigation and development for the treatment of atherosclerotic diseases in clinical practice.

Herein, a general electrochemical radical-cation-mediated four-component ring-opening 1,3-alkyloxylimidation of arylcyclopropanes, acetonitrile, carboxylic acids, and alcohols is described, providing a facile and sustainable approach to quickly construct structurally diverse imide derivatives from easily available raw materials in an operationally simple undivided cell. This metal-catalyst- and oxidant-free single-electron oxidation strategy offers a green alternative for the formation of highly reactive cyclopropane-derived radical cations, and this protocol features a broad functional group tolerance.

This article presents a passive wireless weighing sensor based on surface acoustic wave (SAW) technology. It consists of a one-port SAW sensing resonator and force-sensitive structure. Stable temperature (ST)-cut quartz was employed as the piezoelectric substrate of the SAW sensing resonator, and the sensing characteristics of the SAW sensitive resonator were simulated by the finite element method (FEM). The double-connected holes structure was proposed to form a difference sensing unit, which improves the sensitivity of the sensor and can counteract the effects of ambient temperature. Based on the designed force-sensitive structure and SAW sensing resonator, a wireless passive SAW weighing test platform was built and tested. The experimental result shows that the sensor is consistent with the design expectation. The sensitivity of the weighing sensor is 75.35 kHz/kg, and the nonlinear error is 0.17%. Under consecutive loading and unloading of 0–5 kg, the hysteresis is 1.1% and the maximum standard deviation of repeatability under the same load is 2.277 kHz (about 0.6% of the full-scale frequency shift). The difference structure effectively improves the sensitivity and has a good ambient temperature inhibition effect. Under a temperature of 30 °C–60 °C, the frequency shift is within 3 kHz, which is 0.8% of the full scale.

Vibration issues of a five-stand tandem cold rolling mill were found in the steel production practice, and the experimental observation and numerical analysis indicated that the vibrations were related to the back-up roll bearing. The results were validated by replacing the back-up roll bearing with the new bearing resulting in 30% decline in vibration amplitude. Models describing the four-row cylindrical roller bearing and the vertical system of the cold rolling mill including the bearing were established. Moreover, the mechanisms of periodic excitation and amplified vibrations of fault-free bearing were explained theoretically, along with the analysis of bifurcation behaviors of the motion states of the roller bearing and rolling mill system. It is found that the energy transmitted between vibrations with different frequencies if multiple excitation frequencies in the rolling mill system were close.

Theabrownins (TBs) are the characteristic functional and quality components of dark teas such as Pu'er tea and Chin-brick tea. TBs are a class of water-soluble brown polymers with multi-molecular weight distribution produced by the oxidative polymerisation of tea polyphenols during the fermentation process of dark tea, both enzymatically and non-enzymatically. TBs have been extracted and purified from dark tea all the time, but the obtained TBs contain heterogeneous components such as polysaccharides and caffeine in the bound state, which are difficult to remove. The isolation and purification process was tedious and required the use of organic solvents, which made it difficult to industrialise TBs. In this study, epigallocatechin (EGC), epigallocatechin gallate (EGCG), epigallocatechin gallate (ECG), EGC/EGCG (mass ratio 1:1), EGCG/ECG (mass ratio 1:1), EGC/ECG (mass ratio 1:1) and EGC/EGCG/ECG (mass ratio 1:1:1) as substrates and catalyzed by polyphenol oxidase (PPO) and peroxidase (POD) in turn to produce TBs, named TBs-dE-1, TBs-dE-2, TBs-dE-3, TBs-dE-4, TBs-dE-5, TBs-dE-6 and TBs-dE-7. The physicochemical properties and the antibacterial activity and mechanism of TBs-dE-1–7 were investigated. Sensory and colour difference measurements showed that all seven tea browning samples showed varying degrees of brownish hue. Zeta potential in aqueous solutions at pH 3.0–9.0 indicated that TBs-dE-1–7 was negatively charged and the potential increased with increasing pH. The characteristic absorption peaks of TBs-dE-1–7 were observed at 208 and 274 nm by UV-visible (UV-vis) scanning spectroscopy. Fourier transform infrared (FT-IR) spectra indicated that they were phenolic compounds. TBs-dE-1–7 showed significant inhibition of Escherichia coliDH5α (E. coliDH5α). TBs-dE-3 showed the strongest inhibitory effect with minimum inhibitory concentration (MIC) of 1.25 mg mL–1and MBC of 10 mg mL–1, followed by TBs-dE-5 and TBs-dE-6. These three TBs-dEs were selected to further investigate their inhibition mechanism. The TBs-dE was found to damage the extracellular membrane of E. coliDH5α, causing leakage of contents, and increase intracellular reactive oxygen content, resulting in abnormal cell metabolism due to oxidative stress. The results of the study provide a theoretical basis for the industrial preparation and product development of TBs.

This article considers the consensus problem of uncertain multiagent systems, which is addressed by neuroadaptive impulsive control schemes. The proposed control schemes indicate that the communication among agents only occurs impulsively, while the dynamics uncertainty is addressed by adaptive schemes using neural networks. Based on such approaches, two specific control schemes are designed. One is that with impulsive feedback, the control scheme uses continuous-time information, which implies that the adaptive process is continuous over time. Another is that by adopting sampled information, the update of all systems, including the feedbacks on agents, the update of neural networks, and the estimation for uncertainty, can be executed only at impulsive instants. The latter case can reduce the energy cost for communication and control, but extra assistant systems are required. The estimation and consensus prove to be achieved with errors if some conditions are fulfilled. Numerical simulations, including a practical system example, are presented.