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In this study, the effect of electro-pulsing combining laser shock peening (EP-LSP) treatment on the microstructure and corrosion resistance of Ti-6Al-4V alloys was investigated, and the hardness, surface roughness, microstructure, and electrochemical properties of Ti-6Al-4V alloys after EP-LSP treatment were studied and compared with those of single EPed and LSPed samples. Also, to investigate the effect of the number of laser impacts on microstructure and corrosion resistance, changes in samples after one and three laser impacts were compared. The results showed that all treatments improved the hardness of as-received sample and three EP-LSPed (3 EP-LSP) samples had the maximum hardness which increased 24.3% compared with the as-received sample. As the number of laser impacts increased from one to three, the surface hardness increased, but the surface quality decreased, and the surface showed periodic protrusions. The one EP-LSPed (1 EP-LSP) sample showed the best corrosion resistance, with a 73.2% reduction in corrosion current density compared to the as-received sample. This is due to the grain refinement and the transformation of the α to β phase in the EP-LSPed samples. It has a beneficial effect on the formation of dense passive film. In addition, the sample surface with one impact has lower surface roughness and better surface quality compared to that of three impacts. [ABSTRACT FROM AUTHOR]

This Letter presents an active control method for the vibration of piezoelectric structures. First, a controller based on nonlinear extended state observer is designed to improve the disturbance rejection capability of the vibration structure. Additionally, an improved nonlinear active disturbance rejection control (IMNADRC) method is combined with Smith predictor for time delay compensation, resulting in Smith predictor-based IMNADRC. Finally, numerical simulations and experiments are carried out for active vibration suppression of piezoelectric beam under fixed harmonic excitation and variable harmonic excitation, respectively. The results show that the proposed method has good control effect on structural vibration suppression and is highly adaptable to various external excitations. [ABSTRACT FROM AUTHOR]

Electropulsing (EP)-assisted laser shock peening (LSP), involving the synchronous application of EP and LSP to Ti-6Al-4V samples, represents an innovative surface strengthening technology. A comprehensive series of evaluations and examinations were conducted to thoroughly investigate the effects of EP-assisted multiple laser shock processing impacts on the mechanical behaviour and subsurface characteristics of the Ti-6Al-4V sample. The strength and ductility properties, fatigue performance, microstructure features in subsurface regions and deformation characteristics at various depths of the treated Ti-6Al-4V samples were investigated. The results revealed that as the number of impacts increased, a prominent multilayered structure, including a remelting layer, a severe plastic deformation region, and a plastic deformation-affected zone in the subsurface developed. The observed increase in strength can be attributed to grain refinement, an increase in dislocation density and the presence of high-density nanotwins within the subsurface layer. A high fatigue life was achieved by EP-assisted multiple LSP, with a ∼328.1 % increase compared with that of the as-received sample.The improvement in durability is mainly related to the enhanced subsurface structure acted as a barrier to crack propagation. • Electropulsing assisted multiple laser shock peening at low pulse energy can improve the mechanical properties of Ti-6Al-4V. • An multilayered structure is formed, including a remelting layer, a deformation region, and a deformation-affected zone within the subsurface. • Electropulsing-assisted multiple laser shock processing impacts improve the fatigue life of Ti-6Al-4V samples by 3.28 times. • The finer grains, high-density dislocations and nanotwins significantly contribute to the enhanced fatigue performance. [ABSTRACT FROM AUTHOR]

In this study, the rough surfaces of additive manufactured parts were polished using an innovative combined treatment of continuous wave (CW) laser and inclined femtosecond (fs) laser techniques. The high-temperature friction and wear performances of the initial surface and the polished surface were investigated. The results indicate that the surface roughness was reduced to 0.21 µm and a fine-grained layer of approximately 25 µm was generated through CW-fs laser polishing. The coefficient of friction and wear volume of the CW-fs laser polished surface showed the most significant reductions of 52.2 % and 88.3 %, respectively, compared to those of initial surface under high-temperature conditions. • A new treatment was proposed to improve the friction and wear performance of SLM processed 316L stainless steel. • The surface roughness reduces from 16.2 μm to 2.4 μm and a fine-grained layer was formed by CW laser polishing. • CW-fs laser polishing can reduces COF and wear volume of initial surface by 52.2% and 88.3%, respectively. • The CW-fs polishing reduces COF, surface defects, wear rate due to a protective oxide glaze. [ABSTRACT FROM AUTHOR]

The thread cold rolling process is an advanced produce for manufacturing thread parts. During this process, friction between the rolling die and the workpiece significantly influences the deformation process and the quality of the formed thread parts. However, material deformation and contact conditions between the rolling die and workpiece are complex, posing challenges to the study of friction during the deformation process. A single-tooth rolling friction test (STRFT) was proposed to investigate friction properties in the thread cold rolling process and surface morphology of the formed part. Moreover, the effects of friction on material flow behavior and stress distribution characteristics were investigated. Experiments were performed under various lubrication conditions, and finite element simulation was used to calibrate the friction factor. Rolling torque was significantly affected by the friction factor and regarded as the sensitive parameter. The friction factor m was determined as 0.16 under lubrication condition by comparing the torque during the test and the simulation. A larger friction factor increased deformation stress and decreased material flow speed. The bottom of the formed groove under larger deformation stress exhibited greater roughness and more surface defects than the flank. [ABSTRACT FROM AUTHOR]

Intelligent reflecting surface (IRS) is a promising technology to extend the wireless signal coverage and support the high performance communication. By intelligently adjusting the reflection coefficients of a large number of passive reflecting elements, the IRS can modify the wireless propagation environment in favour of signal transmission. Different from most of the prior works which did not consider any cooperation between IRSs, in this work we propose and study a cooperative double-IRS aided multiple-input multiple-output (MIMO) communication system under the line-of-sight (LoS) propagation channels. We investigate the capacity maximization problem by jointly optimizing the transmit covariance matrix and the passive beamforming matrices of the two cooperative IRSs. Although the above problem is non-convex and difficult to solve, we transform and simplify the original problem by exploiting a tractable characterization of the LoS channels. Then we develop a novel low-complexity algorithm whose complexity is independent of the number of IRS elements. Moreover, we analyze the capacity scaling orders of the double-IRS aided MIMO system with respect to an asymptotically large number of IRS elements or transmit power, which significantly outperform those of the conventional single-IRS aided MIMO system, thanks to the cooperative power gain brought by the double-reflection link and the spatial multiplexing gain harvested from the two single-reflection links. Extensive numerical results are provided to show that by exploiting the LoS channel properties, our proposed algorithm can achieve a desirable performance with low computational time. Also, our capacity scaling analysis is validated, and the double-IRS system is shown to achieve a much higher rate than its single-IRS counterpart as long as the number of IRS elements or the transmit power is not small. [ABSTRACT FROM AUTHOR]

Intelligent reflecting surface (IRS) is a new promising technology that is able to reconfigure the wireless propagation channel via smart and passive signal reflection. In this paper, we investigate the capacity region of a two-user communication network with one access point (AP) aided by $M$ IRS elements for enhancing the user-AP channels, where the IRS incurs negligible delay, thus the user-AP channels via the IRS follow the classic discrete memoryless channel model. In particular, we consider two practical IRS deployment strategies that lead to different effective channels between the users and AP, namely, the distributed deployment where the $M$ elements form two IRSs, each deployed in the vicinity of one user, versus the centralized deployment where all the $M$ elements are deployed in the vicinity of the AP. First, we consider the uplink multiple-access channel (MAC) and derive the capacity/achievable rate regions for both deployment strategies under different multiple access schemes. It is shown that the centralized deployment generally outperforms the distributed deployment under symmetric channel setups in terms of achievable user rates. Next, we extend the results to the downlink broadcast channel (BC) by leveraging the celebrated uplink-downlink (or MAC-BC) duality framework, and show that the superior rate performance of centralized over distributed deployment also holds. Numerical results are presented that validate our analysis, and reveal new and useful insights for optimal IRS deployment in wireless networks. [ABSTRACT FROM AUTHOR]

Laser shock peening (LSP) is an efficient surface treatment method used to improve the mechanical properties of materials. With the growing demand for high-performance components under extreme conditions, there is a need for further improvement in the effects of LSP. Recently, electro-pulsing assisted laser shock peening (EP-LSP) has emerged as a promising technique to enhance the effects of single-mechanical-field LSP. However, there has been limited systematic research on the effects of mechanical properties and strengthening mechanisms of material treating by EP-LSP. Herein, Ti‐6Al‐4V samples were subjected to synchronous treatment with electro-pulsing and LSP. The effects of EP-LSP on surface and subsurface characteristics, including surface morphology, hardness, residual stress and microstructure, were investigated and compared with both as-received and LSP-treated samples. Furthermore, the strength and ductility properties were carefully analyzed, and the strengthening mechanism was elucidated. It was observed that EP-LSP produced greater plastic deformation, inducing higher surface hardness and compressive residual stress. Tensile tests demonstrated that the EP-LSP-treated samples exhibited an increase of 7.5% in yield strength, 8.4% in ultimate tensile strength, and 19.7% in elongation compared to LSP-treated samples. Further analysis of the microstructure revealed significant phase transformation and recrystallization in the EP-LSP-treated sample. The increasing dislocation density, nano-twins and grain refinement had contributions to the strength, with nano-twins having the most significant contribution. [Display omitted] • The EP-LSP-treated sample has greater local plastic deformation and larger residual stress than LSP-treated sample. • The maximum yield stress and elongation of sample treated by EP-LSP process synchronously increases by 10.1% and 3.4%. • The maximum microhardness values of EP-LSP-treated sample increases 14.3% and 27.7% than LSP-treated and as-received sample. • The nano-twins make the most significant contributions to the strength in EP-LSP-treated sample. [ABSTRACT FROM AUTHOR]

Intelligent reflecting surface (IRS) is an enabling technology to engineer the radio signal propagation in wireless networks. By smartly tuning the signal reflection via a large number of low-cost passive reflecting elements, IRS is capable of dynamically altering wireless channels to enhance the communication performance. It is thus expected that the new IRS-aided hybrid wireless network comprising both active and passive components will be highly promising to achieve a sustainable capacity growth cost-effectively in the future. Despite its great potential, IRS faces new challenges to be efficiently integrated into wireless networks, such as reflection optimization, channel estimation, and deployment from communication design perspectives. In this paper, we provide a tutorial overview of IRS-aided wireless communications to address the above issues, and elaborate its reflection and channel models, hardware architecture and practical constraints, as well as various appealing applications in wireless networks. Moreover, we highlight important directions worthy of further investigation in future work. [ABSTRACT FROM AUTHOR]

Forming process of internal thread is an advanced manufacturing process. A new planetary rolling process for forming the internal thread is proposed. The structures of rolling system and working process are described in detail. The finite element model of forming internal thread is established, and the forming experiments are conducted by a homemade experimental rig. The material displacement, microstructure, strain, and microhardness are investigated by finite element model and experiment. The results show that the formed internal thread meets requirements and the results of simulation and experiment are consistent. Through the planetary rolling process, the microstructure is stretched and forms the fibrous tissue at the bottom of tooth space of the internal thread. The maximum deformation is located at the bottom of tooth space, and the deformation characteristics are corresponding to the microstructure distribution. At the bottom of tooth space, the microhardness and the equivalent strain are also largest. The maximum microhardness of formed internal thread is improved 37.6%. The new planetary rolling process can improve the production performances and simplify the processing equipment. [ABSTRACT FROM AUTHOR]

In this paper, the self-infeed rolling process of thread shaft with medium carbon steel AISI 1045 is investigated. Firstly, the principle of the self-infeed rolling process is introduced and then the deformation mechanism is analyzed by finite element method. The numerical results show that deformation mainly occurs on the surface layer of blank, and the deformation degree is different in the tooth profile. The metal flows along both the axial direction and the radial direction. Next, the experimental studies of self-infeed rolling process are carried out. The numerical results are shown in good accordance with the experimental results. The grain at the top of tooth profile is refined, and the microstructures in the surface of tooth profile as well as bottom of tooth root are fibrous tissue which is dense and streamlined obviously. The hardness of the formed thread shaft is improved than that of the blank. [ABSTRACT FROM AUTHOR]

Driven by the recent advancement in unmanned aerial vehicle (UAV) technology, this paper proposes a new wireless network architecture of coordinate multipoint (CoMP) in the sky to harness both the benefits of interference mitigation via CoMP and high mobility of UAVs. Specifically, we consider uplink communications in a multi-UAV enabled multi-user system, where each UAV forwards its received signals from all ground users to a central processor (CP) for joint decoding. Moreover, we consider the case where the users may move on the ground, thus the UAVs need to adjust their locations in accordance with the user locations over time to maximize the network throughput. Utilizing random matrix theory, we first characterize, in closed form, a set of approximated upper and lower bounds of the user’s achievable rate in each time epoch under the practical Rician fading channel model, which is shown to be very tight, both analytically and numerically. UAV placement and movement over different epochs are then optimized based on the derived bounds to maximize the minimum of user average achievable rates over all epochs for both cases of full information (of current and future epochs) and current information on the user’s movement. Interestingly, it is shown that the optimized location of each UAV at any particular epoch is the weighted average of the ground user locations at the current epoch as well as its own location at the previous and/or next epoch. Finally, simulation results are provided to validate and compare the performance of the proposed UAV placement and movement designs under different practical application scenarios. [ABSTRACT FROM AUTHOR]

Constant envelope (CE) precoding is an appealing transmission technique which enables highly efficient power amplification. In this paper, we consider a point-to-point multiple-input multiple-output (MIMO) system with CE precoding under frequency-flat fading, and investigate the joint transceiver design by exploiting multiple antennas at both the transmitter and the receiver, which has not been addressed in prior work. We consider both single-stream transmission (i.e., beamforming) and multi-stream transmission (i.e., spatial multiplexing). For single-stream transmission, we optimize the receive beamforming vector to minimize the symbol error rate (SER) for any given channel realization and desired constellation at the combiner output. By reformulating the problem as an equivalent quadratically constrained quadratic program, we propose an efficient semi-definite relaxation based algorithm to find an approximate solution. Next, for multi-stream transmission, we propose a new scheme based on antenna grouping at the transmitter and minimum mean squared error or zero-forcing based beamforming at the receiver. The transmit antenna grouping and receive beamforming vectors are then jointly designed to minimize the maximum SER over all data streams. Numerical results show that our proposed schemes for both single- and multi-stream transmissions achieve superior error-rate performances as compared with various benchmark schemes. Finally, the error-rate performances of our proposed single- versus multi-stream transmission schemes are compared via simulations under different setups, which provide useful insights to the transmission mode selection for CE-precoded MIMO systems. [ABSTRACT FROM AUTHOR]

This study explores the association of serum 25-hydroxyvitamin D3 (25(OH)D3) levels with carotid artery intima-media thickness (CIMT), and the presence of carotid atherosclerotic plaques in individuals with a history of smoking. A total of 469 patients suspected of having carotid atherosclerosis, aged 52 to 73 years with an average age of 65.26 ± 4.37 years, were recruited from the author's hospital from January 2023 to October 2023. All patients had a smoking history of nearly 5 years. Based on their serum 25(OH)D3 levels, they were divided into two groups: the normal group (serum level 30–50 ng/mL, n = 300) and the deficiency group (<30 ng/mL, n = 169). General details of the two patient groups were collected. Carotid artery ultrasound was employed to assess pulse wave velocity (PWV), carotid artery compliance coefficient (CC), and CIMT. Blood chemistry analysis measured serum lipid metabolism indicators including total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HD-LC). The relationship between CIMT and each variable was analyzed through Pearson correlation, and logistic regression was used to identify risk factors influencing carotid artery plaque development. General patient information between the two groups showed no significant differences (P > 0.05). Patients in the 25(OH)D3 deficiency group exhibited elevated left and right PWV and CC compared to the 25(OH)D3 normal group (P < 0.05). The deficiency group exhibited larger CIMT and plaque area compared to the normal group (P < 0.05). Additionally, the deficiency group demonstrated higher levels of TC, LDL-C, and HD-LC compared to the normal group (P < 0.05). A moderate positive correlation was found between TC, LDL-C, and CIMT (P < 0.05), while a strong positive correlation existed between 25(OH)D3 and CIMT (P < 0.05). In smokers, the formation of carotid artery plaque was associated with factors such as patient age, CIMT, serum LDL-C, and 25(OH)D3 levels (P < 0.05). As age, CIMT, LDL-C levels increased, and 25(OH)D3 levels decreased, the risk of carotid plaques in smokers increased (P < 0.05). Smokers with lower 25(OH)D3 levels exhibit higher CIMT and more prominent carotid atherosclerotic plaques, indicating increased arterial stiffness and elevated cardiovascular risk. These findings demonstrate crucial implications that insufficient levels of vitamin D may potentially contribute to a higher risk of atherosclerosis among smokers. [Display omitted] [ABSTRACT FROM AUTHOR]

• The blind zone formed in SLCS is effectively eliminated in DLSC. • Nanoparticles originally in the blind zone below a single plasma kernel expose to multiple plasma kernels in DLSC. • The angle between the two laser beams is critical for altering the intensity and the geometric location of the plasma kernels to eliminate the blind zone. • The introduction of multiple plasma shockwave fronts significantly increase the horizontal rolling torque acting on the nanoparticles, therefore facilitating their removal. Laser shockwave cleaning (LSC) has been gaining increasing attention due to its advantages in decontaminating various micron- and nano-scale contaminated particles on silicon (Si) wafer surfaces. However, the particles in a blind zone right under the laser-induced plasma, the origin of the shockwave, cannot be removed efficiently, thereby impeding the conventional LSC process in industrial wafer cleaning applications. Here, we demonstrate a simple but intriguing method of eliminating the blind zone in nanoparticle removal on Si wafers by employing a double-beam laser shockwave cleaning process (DLSC). The size of the uncleaned blind zone in DLSC is reduced by 98% compared to the traditional single-beam LSC (SLSC) process with a laser pulse energy of 150 mJ and a gap distance between the laser focus and the wafer of 1 mm. The time-resolved, laser-induced plasma evolution reveals that the steady single-laser-beam-induced plasma splits into multiple plasma kernels distributed around the focus point due to the disruption from the second laser beam. The formation of multiple plasma kernels makes it possible to expose the particles in the blind zone to the cleaning-effective zone of the shockwave from a nearby passing plasma. The angle between the two laser beams plays a critical role in eliminating the blind zone. The comparison of the particle removal force between DLSC and SLSC suggests that the horizontal drag force from a nearby passing plasma acts on the particles in the blind zone and facilitates their removal. [ABSTRACT FROM AUTHOR]

Titanium alloy threaded fasteners offer great advantages to the field of aerospace. But the use of cold rolling process when forming threaded fasteners has the disadvantages of short die life and high apparatus requirements because of poor plasticity of titanium alloy at room temperature. This paper uses a combination of axial infeed rolling process and intermediate frequency induction heating to fabricate thread with Ti6Al4V. First, the principle of hot rolling process is introduced, and then the characteristics of induction heating and the strain, displacement, and metal flow law of the thread during hot rolling process are analyzed by using finite element analysis. The influence of different forming temperatures on the rolling torque and the major diameter of the formed thread are analyzed. According to the results of finite element analysis, the best forming temperature for hot rolling process is 800 °C. Moreover, experiments are carried out on related equipment, and the experimental results are similar to the simulation results. The torque is reduced by 74% relative to that in cold rolling process. Finally, the microstructure and hardness of the formed thread are observed. A dense and directional microstructure appeared on the surface of the formed thread. The overall hardness of the thread after hot rolling is higher than that of cold rolling, and the maximum hardness of formed thread is increased by 35% relative to that of the original metal. [ABSTRACT FROM AUTHOR]

Mixed lubrication describes a lubrication regime where elastohydrodynamic lubrication and asperity contact coexist. Surface spacing is expected to be small during the interaction between nano-scale smooth surfaces. When alkali metal salt solution is applied as lubricant, short-range surface forces are incorporated into an existing model to simulate mixed lubricated non-conformal sliding contact. The new model is examined in a wide range of sliding velocities to demonstrate the effect of surface forces at different lubrication regime, from boundary lubrication to full film hydrodynamic lubrication. It is revealed that surface forces reduce friction coefficient particularly at mixed lubrication regime. Reduction of surface roughness improves contribution of surface forces and makes it easier to achieve superlubricity at low speed. • Model and analyze surface force effect on water-based lubrication. • Surface force effect conduces to achievement of ultra-low friction. • Surface forces mainly take effect at mixed lubrication regime. • Contribution of surface forces is enhanced with decrease of surface roughness. [ABSTRACT FROM AUTHOR]

Intelligent reflecting surface (IRS) is a promising new technology for achieving both spectrum and energy efficient wireless communication systems in the future. However, existing works on IRS mainly consider frequency-flat channels and assume perfect knowledge of channel state information (CSI) at the transmitter. Motivated by the above, in this paper we study an IRS-enhanced orthogonal frequency division multiplexing (OFDM) system under frequency-selective channels and propose a practical transmission protocol with channel estimation. First, to reduce the overhead in channel training as well as exploit the channel spatial correlation, we propose a novel IRS elements grouping method, where each group consists of a set of adjacent IRS elements that share a common reflection coefficient. Based on this method, we propose a practical transmission protocol where only the combined channel of each group needs to be estimated, thus substantially reducing the training overhead. Next, with any given grouping and estimated CSI, we formulate the problem to maximize the achievable rate by jointly optimizing the transmit power allocation and the IRS passive array reflection coefficients. Although the formulated problem is non-convex and thus difficult to solve, we propose an efficient algorithm to obtain a high-quality suboptimal solution for it, by alternately optimizing the power allocation and the passive array coefficients in an iterative manner, along with a customized method for the initialization. Simulation results show that the proposed design significantly improves the OFDM link rate performance as compared to the case without using IRS. Moreover, it is shown that there exists an optimal size for IRS elements grouping which achieves the maximum achievable rate due to the practical trade-off between the training overhead and IRS passive beamforming flexibility. [ABSTRACT FROM AUTHOR]

To solve the problem of the poor abrasion resistance of concrete pavement surface mortar, this study substituted cement with equal amounts of styrene–butadiene rubber (SBR) latex and silica fume (SF) to investigate the effects of organic/inorganic material composite modification on the fluidity, drying shrinkage, mechanical properties, and abrasion resistance of cement mortar. Also in this study, the microstructure, product, and pore structure characteristics of the composite modified cement mortar were investigated using scanning electron microscope (SEM), X-Ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and the Brunauer–Emmett–Teller (BET) method. This research found that the sole substitution of SF negatively impacted the mortar's fluidity and drying shrinkage yet enhanced its mechanical strength and abrasion resistance; the incorporation of SBR latex improved fluidity, reduced shrinkage, and increased flexural strength but adversely affected the compressive strength of the mortar. Additionally, the enhancement of the mortar's abrasion resistance with SBR latex was significantly greater than that with SF. When SBR latex and SF were used together as substitutes, the latex struggled to offset the negative impact of SF on mortar fluidity but effectively reduced shrinkage; SF compensated for the detrimental effect of the latex on compressive strength. Moreover, the primary role in enhancing the mortar's abrasion resistance was played by the latex. Microscopic tests showed that SBR latex and SF could increase the content of calcium silicate hydrate (C-S-H) gel, inhibit the formation of ettringite (AFt) and reduce carbonation, refine the pore size of cement mortar, and effectively improve the microstructure of mortar. [ABSTRACT FROM AUTHOR]

Balancing quality and productivity, especially deciding on the optimal matching strategy for multiple process parameters, is challenging in ultrashort laser processing. In this paper, an economical and new processing strategy was studied based on the laser scribing case. To reveal the temperature evolution under the combination of multiple process parameters in the laser scribing process, a two-temperature model involving a moving laser source was developed. The results indicated that the peak thermal equilibrium temperature between the electron and lattice increased with the increase in the laser fluence, and the temperature evolution at the initial position, influenced by subsequent pulses, was strongly associated with the overlap ratio. The thermal ablation effect was strongly enhanced with the increase in laser fluence. The groove morphology was controllable by selecting the overlap ratio at the same laser fluence. The removal volume per joule (i.e., energy utilization efficiency) and the removal volume per second (i.e., ablation efficiency) were introduced to analyze the ablation characteristics influenced by multiple process parameters. The law derived from statistical analysis is as follows; at the same laser fluence with the same overlap ratio, the energy utilization efficiency is insensitive to changes in the repetition rate, and the ablation efficiency increases as the repetition rate increases. As a result, a decision-making strategy for balancing quality and productivity was created. [ABSTRACT FROM AUTHOR]

High performance supercapacitors are promising to address the rising energy conversion and storage challenges. Revealing the role of heteroatom incorporation and nanoparticle anchoring in modifying the capacitive properties of graphene-based electrodes is scientifically important to boost the supercapacitor performance, but technically challenging. We demonstrate a simple, but efficient route to fabricate porous graphene with effective heteroatom incorporation and metal nanoparticles anchoring by laser direct writing metal-coated polyimide films. Silver (Ag), copper (Cu), titanium (Ti), and tellurium (Te) are introduced into the porous laser-induced graphene (LIG) as dopants and nanoparticles. Compared to Ti and Te, Ag and Cu exhibit high incorporation efficiency. Incorporation of Ag and Cu into the LIG sheets results in high level disorder and structure expansion, which contributes to the enhanced capacitive performance. All-solid-state micro-supercapacitors (MSCs) made from the metal-incorporated LIGs (M-LIGs) were assembled. The capacity performance of M-LIG-based MSCs exhibits a similar variation trend with respect to the metal type. Besides, the M-LIG-based MSCs exhibit excellent capacitance stability at a bending angle beyond 150°. The results suggest that the effective metal doping and the metal nanoparticle modification could elevate the structural defect density in graphene, therefore contributing to high carrier density and enhanced capacitive performance. [Display omitted] Brief Summary: we demonstrate a rapid laser direct writing method to fabricate LIGs doped with various metal atoms. Flexible all-solid-state micro-supercapacitors (MSCs) using the metal-doped LIG electrodes were assembled. According to the morphological and structural characterization of the metal-modified LIGs, the mechanism about the effect of metal doping and nanoparticle modification on graphene property is discussed in detail. [ABSTRACT FROM AUTHOR]

This study investigated the effects of light-burned magnesia, fly ash (FA), dolomite powder (DP), and limestone powder (LP) contents on the performance of magnesium oxychloride cement lean concrete (MOCLC). The effects of light-burned magnesia and mineral admixture content on the mechanical properties and durability of MOCLC were tested by the compressive strength test, splitting strength test, water resistance test, shrinkage test, and fatigue test, respectively. The results revealed that the optimum dosage of MgO was 4%. The optimum dosages of FA, DP, and LP were 25%, 20%, and 20% of the cement dosage, respectively. The compressive and splitting strengths of the MOCLC were decreased by the addition of FA and DP. Due to part of the internal pores of MOCLC were filled with FA and DP, the decomposition of the main strength phase 5Mg (OH)2·MgCl2·8H2O (phase 5) was suppressed and the water resistance of MOCLC was improved. The addition of FA and DP also improved the shrinkage resistance, and the fatigue resistance of MOCLC was also improved by the addition of FA and DP. The water resistance, shrinkage, and fatigue properties of MOCLC with a FA content of 25% were better than those of MOCLC with DP and LP. [ABSTRACT FROM AUTHOR]

Memristors in a metal/oxide/metal configuration emerge as an advanced non-volatile information storage technology due to their high operating speed and low power consumption. Understanding the role of the microstructure of the active oxide layer in its resistive switching (RS) performance is scientifically important for revealing the conduction mechanism of oxides, and technically critical for the development of high-performance memristors. Here, self-assembly of vertically aligned CeO 2 nanobrushes, a typical RS material, is demonstrated in pulsed laser epitaxy. The growth map of CeO 2 is fully explored, and optimized growth conditions for CeO 2 nanobrushes are established. Microstructure and crystallinity characterizations reveal the single-crystalline epitaxy nature of CeO 2 nanobrushes. A nanobrush memristor exhibits a threshold switching feature with an On/Off ratio of 50, as 16 times high as a thin-film memristor, and excellent endurance of up to 500 cycles and retention time of up to 104 seconds. Theoretical fitting of the I-V curves of the thin-film and nanobrush memristors show interfacial switching in the thin-film memristor and filamentary switching in the nanobrush memristor. The distinct RS mechanisms between thin films and nanobrushes suggest the fundamental role of the structural design of active oxide layers in the RS performance of oxide-based memristors. • Vertical self-assembly of CeO 2 nanobrushes was achieved using pulse laser epitaxy, with full exploration of the growth map and optimization of growth conditions. • A nanobrush memristor exhibits threshold switching characteristics with a high On/Off ratio of 50 and a retention time of up to 104 seconds. • CeO 2 nanobrush memristors exhibit filamentary threshold switching compared to thin-film memristors, highlighting the role of structural design in conductive filament formation. • The CeO 2 nanobrushes, with their ∼15 nm diameter, vertical alignment, and low threshold filamentary switching, are promising as selectors for cross-switching memory architectures, effectively suppressing interference. [ABSTRACT FROM AUTHOR]

The hot forged Ti–6Al–4V alloy demonstrates well constructed microstructure and balanced mechanical properties, which promotes its wide application in aviation field. However, its relative poor resistance to wear and foreign object impact usually leads to the cumulative damage, causing sudden failure and serious accident. Laser shock peening (LSP) is a novel surface plastic deformation technique, which could strengthen the surface layer of components through gradient grain structure. Nevertheless, the specific mechanism of microstructure evolution and mechanical properties enhancement of LSP processed hot forged Ti–6Al–4V alloy is still obscure, and its corresponding explanation would help the wide application. In the present research, the hot forged Ti–6Al–4V alloy was processed by LSP to regulate its superficial microstructure and improve mechanical properties, helping to understand the inner mechanism. The results reveal that LSP could simultaneously result in the merging of ultrafine α-Ti grains and refinement of coarse α-Ti grains, which reconstruct the dual-size grain structure. The crystal tilting and transformation promoted by the generation and movement of dislocations benefit the merging of ultrafine grains. Due to the different slip systems in dual phases, β-Ti phases exhibit much greater response to slip under surface plastic deformation, which are enforced to deform and construct the shell structure by sliding and phase transformation, while the α-Ti phases act as the core to synergistically construct 'core-shell' like structure. The increase of LSP impact time promotes the well wrapping of the 'core-shell' like structure and strengthens it by abundant dislocations, which also forms the gradient grain structure from surface to inner. Since the microstructure regulation and crystal defects engineering, the LSP improves the surface damage resistance and mechanical properties of the hot forged Ti–6Al–4V alloy obviously. Such results indicate a new technology to increase the properties of the hot forged Ti–6Al–4V alloy component further. [Display omitted] • The dislocation movement and crystal tilting induced by one-time laser shock peening refine coarse α-Ti grains but merge ultra-fine α-Ti grains. • The increased impact time of laser shock peening optimizes the crystal orientation and grain structure in surface layer. • The slipping and transformation of β-Ti phase promote the formation of 'core-shell' like structure. • Laser shock peening simultaneously improves mechanical properties and wear resistance of the hot-forged Ti–6Al–4V alloy further. [ABSTRACT FROM AUTHOR]

Anti–programmed cell death protein 1 (PD-1) therapy provides long-term clinical benefits to patients with advanced melanoma. The composition of the gut microbiota correlates with anti–PD-1 efficacy in preclinical models and cancer patients. To investigate whether resistance to anti–PD-1 can be overcome by changing the gut microbiota, this clinical trial evaluated the safety and efficacy of responder-derived fecal microbiota transplantation (FMT) together with anti–PD-1 in patients with PD-1–refractory melanoma. This combination was well tolerated, provided clinical benefit in 6 of 15 patients, and induced rapid and durable microbiota perturbation. Responders exhibited increased abundance of taxa that were previously shown to be associated with response to anti–PD-1, increased CD8+ T cell activation, and decreased frequency of interleukin-8– expressing myeloid cells. Responders had distinct proteomic and metabolomic signatures, and transkingdom network analyses confirmed that the gut microbiome regulated these changes. Collectively, our findings show that FMT and anti–PD-1 changed the gut microbiome and reprogrammed the tumor microenvironment to overcome resistance to anti–PD-1 in a subset of PD-1 advanced melanoma. [ABSTRACT FROM AUTHOR]

This study investigates a hybrid surface enhancement technique that combines Quench Polish Quench (QPQ) with ultrasonic rolling to augment the durability of 42CrMo gears against wear and fatigue. Analysis reveals that post-treatment, the composite nitride layer on the gear surface maintains its original phase composition, evidenced by the absence of new diffraction peaks in X-ray diffraction (XRD) patterns. Nevertheless, a noticeable broadening in these peaks suggests grain refinement and the presence of microstrain due to the rolling process. Incremental static pressures improve the mechanical characteristics of the surface, with the layer treated at 0.6 MPa exhibiting the lowest wear rate (3.15 × 10−8 mm3N−1 m−1). Oxidative wear increases at elevated temperatures (100 °C), yet under lubricated conditions, Coefficient Of Friction (COF) of the treated layer significantly reduces. The predominant wear mechanisms include mild abrasive wear, oxidative wear, and adhesion. Excessive impact force, particularly at 0.6 MPa, risks surface cracking and subsequent degradation in fatigue resistance. Optimal fatigue performance is achieved with a static pressure of 0.4 MPa, corresponding to a surface strength of 2300 MPa and a fatigue life of 3.23 × 106 cycles. • Pioneered the composite strengthening method of QPQ and ultrasonic rolling; • Revealed the influence law of composite strengthening process on surface integrity; • The effect of QPQ-coupled ultrasonic rolling on the friction performance of gears was studied. • It is verified that the ultrasonic rolling combined with QPQ strengthening process significantly improves the fatigue life. [ABSTRACT FROM AUTHOR]

We demonstrate a laser annealing method for the rapid growth of high-quality Bi 2 Te 3 thin films. The effects of laser energy density on the microstructure, surface chemistry and crystalline phase of Bi 2 Te 3 thin films were systematically investigated. The laser-annealed Bi 2 Te 3 thin films exhibit superior thermoelectric performance, with their Seebeck coefficients are around 30% higher than that of thermally annealed Bi 2 Te 3 thin films. Rapid formation of high-quality stoichiometric Bi 2 Te 3 thin films by laser annealing paves the path for the development of high-performance thermoelectric devices. [Display omitted] • Fast growth of high-performance Bi 2 Te 3 thin films at room temperature is achieved using a laser annealing method. • Formation of Bi 2 Te 3 can be completed in 10 s by laser annealing due to its fast heating and cooling feature. • The thermoelectric power factors of laser-annealed thin films are 30% higher than that of thermally annealed thin films. • The crystalline structure and phase purity extensively affects the thermoelectric performance of Bi 2 Te 3 thin films. Bismuth telluride, (Bi 2 Te 3), is of great scientific and technical importance due to its excellent thermoelectric performance near room temperature. However, deposition of Bi 2 Te 3 thin films suffers from composition deviation due to preferential loss of Te at a high-temperature deposition environment. We demonstrated a fast and efficient laser annealing method to synthesize high-quality stoichiometric Bi 2 Te 3 thin films at room temperature from Te/Bi stacking films. The production rate of Bi 2 Te 3 was around 180 times higher than conventional thermal annealing. The formation of Bi 2 Te 3 thin films was studied with respect to annealing laser energy density. Bi 2 Te 3 thin films with an Bi:Te atomic ratio of 2:3 were achieved at an annealing laser energy density of 6.6 mJ/cm2. The structural, chemical, and thermoelectric performance of laser-annealed films were compared with conventional thermally annealed films. The Seebeck coefficient of laser-annealed films reached −167 µV/K, which was1.3 higher than that of thermally annealed films, evidencing the superiority of the laser annealing method in producing high quality Bi 2 Te 3 stochiometric films. Rapid growth of stoichiometric Bi 2 Te 3 thin films by laser annealing holds great promise for the development of high-performance thermoelectric devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel crack initiation model is proposed. • Initial load exceeds 140% critical crack initiation load lead to poor cross-section quality. • Reasonable initial load range of 316L, AISI 304, Al 6061, 1045 steel, and 16Mn bar are obtained. The low-cycle fatigue cropping (LCFC) method is a new separation method that has low active load and low energy waste. A crucial challenge for the LCFC is to determine the suitable range of initial load, which impacts the crack initiation and the cross-section quality. This work proposes a novel crack initiation model which considers cumulative plastic deformation, material mechanical properties, notch stress, and material microstructure, and has a simple form. The acoustic emission technique (AET) is used to prove the validity of the model. The finite element method (FEM) and Electron backscatter diffraction (EBSD) are used to assess the effect of various initial loads. A laser confocal microscopy is used to measure the arithmetic mean deviation of the crack initiation area. The validity of the crack initiation model is proven. The critical crack initiation load (CCIL) of 316L, AISI 304, Al 6061, 1045 steel, and 16Mn bar are 2.470 mm, 2.080 mm, 1.310 mm, 2.980 mm, and 2.950 mm, respectively. The reasonable ranges of initial load for 316L, AISI 304, Al 6061, 1045 steel, and 16Mn bar are obtained. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ultrafast laser induced self-growth of micropillars on shape memory polymer in 2.5-dimension. • The sliding angle of water on the micropillar-textured film can be controlled by adjusting micropillar height, diameter, bending angle with superhydrophobic chemical treatment. • By properly design and assembly of straight and bended micropillars, speedy sliding tracks for water droplets are constructed and directional droplet transfer is demonstrated. Directional droplet transfer is essential for water collection, microfluidic and remote material transfer. Laser-enabled 2.5-dimensional fabrication of micropillars on shape-memory-polymers transfers the surface wettability from hydrophilicity to superhydrophobicity in a simple, fast, and large-scale manner. The surface wettability exhibits a tight relationship with the topographic features of the surface microstructures. By adjusting the height, diameter, bending angle of the micropillars as well as superhydrophobic chemical treatment, the contact angles of water droplets on the micropillar-textured surfaces exceed 160° and exhibit finely-tunable sliding angles from 5.4 ± 1.9° to 71.8 ± 5.9°. A water droplet on a surface textured with bended micropillar shows anisotropic sliding behavior depending on the sliding direction and the micropillar bending angle. By properly design and assembly of straight and bended micropillars, speedy sliding tracks are constructed and directional droplet transfer is demonstrated, suggesting great potential in the fields of lossless material transportation, biomedical testing and microfluidic devices. [ABSTRACT FROM AUTHOR]