Equiaxed Ti-based Composites With High Strength And Large Plasticity Prepared By Sintering And Crystallizing Amorphous Powder

High-performance titanium alloys with an equiaxed composite microstructure were achieved by sintering and crystallizing amorphous powder. By introducing a second phase in a β-Ti matrix, series of optimized Ti-Nb-Fe-Co-Al and Ti-Nb-Cu-Ni-Al composites, which have a microstructure composed of ultrafine-grained and equiaxed CoTi2 or (Cu,Ni)Ti2 precipitated phases surrounded by a ductile β-Ti matrix, were fabricated by sintering and crystallizing mechanically alloyed amorphous powder. The as-fabricated composites exhibit ultra-high ultimate compressive strength of 2585MPa and extremely large compressive plastic strain of around 40%, which are greater than the corresponding ones for most titanium alloys. In contrast, the alloy fabricated by sintering and crystallizing Ti-Zr-Cu-Ni-Al amorphous powder, which possesses significantly higher glass forming ability in comparison with the Ti-Nb-Fe-Co-Al and Ti-Nb-Cu-Ni-Al alloy systems, exhibits a complex microstructure with several intermetallic compounds and a typical brittle fracture feature. The deformation behavior and fracture mechanism indicate that the ultrahigh compressive strength and large plasticity of the as-fabricated equiaxed composites is induced by dislocations pinning effect of the CoTi2 or (Cu,Ni)Ti2 second phases and the interaction and multiplication of generated shear bands in the ductile β-Ti matrix, respectively. The results obtained provide basis guidelines for designing and fabricating titanium alloys with excellent mechanical properties by powder metallurgy

Identifying complementary and alternative medicine recommendations for insomnia treatment and care : a systematic review and critical assessment of comprehensive clinical practice guidelines

Background: There is a need for evidence-informed guidance on the use of complementary and alternative medicine (CAM) for insomnia because of its widespread utilization and a lack of guidance on the balance of benefits and harms. This systematic review aimed to identify and summarize the CAM recommendations associated with insomnia treatment and care from existing comprehensive clinical practice guidelines (CPGs). The quality of the eligible guidelines was appraised to assess the credibility of these recommendations. Methods: Formally published CPGs incorporating CAM recommendations for insomnia management were searched for in seven databases from their inception to January 2023. The NCCIH website and six websites of international guideline developing institutions were also retrieved. The methodological and reporting quality of each included guideline was appraised using the AGREE II instrument and RIGHT statement, respectively. Results: Seventeen eligible GCPs were included, and 14 were judged to be of moderate to high methodological and reporting quality. The reporting rate of eligible CPGs ranged from 42.9 to 97.1%. Twenty-two CAM modalities were implicated, involving nutritional or natural products, physical CAM, psychological CAM, homeopathy, aromatherapy, and mindful movements. Recommendations for these modalities were mostly unclear, unambiguous, uncertain, or conflicting. Logically explained graded recommendations supporting the CAM use in the treatment and/or care of insomnia were scarce, with bibliotherapy, Tai Chi, Yoga, and auriculotherapy positively recommended based on little and weak evidence. The only consensus was that four phytotherapeutics including valerian, chamomile, kava, and aromatherapy were not recommended for insomnia management because of risk profile and/or limited benefits. Conclusions: Existing guidelines are generally limited in providing clear, evidence-informed recommendations for the use of CAM therapies for insomnia management due to a lack of high-quality evidence and multidisciplinary consultation in CPG development. More well-designed studies to provide reliable clinical evidence are therefore urgently needed. Allowing the engagement of a range of interdisciplinary stakeholders in future updates of CPGs is also warranted. Systematic review registration: https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=369155, identifier: CRD42022369155. Copyright © 2023 Zhao, Xu, Kennedy, Conduit, Zhang, Wang, Fu and Zheng

Ultrafast consolidation of bulk nanocrystalline titanium alloy through ultrasonic vibration

Nanocrystalline (NC) materials have fascinating physical and chemical properties, thereby they exhibit great prospects in academic and industrial fields. Highly efficient approaches for fabricating bulk NC materials have been pursued extensively over past decades. However, the instability of nanograin, which is sensitive to processing parameters (such as temperature and time), is always a challenging issue to be solved and remains to date. Herein, we report an ultrafast nanostructuring strategy, namely ultrasonic vibration consolidation (UVC). The strategy utilizes internal friction heat, generated from mutually rubbing between Ti-based metallic glass powders, to heat the glassy alloy rapidly through its supercooled liquid regime, and accelerated viscous flow bonds the powders together. Consequently, bulk NC-Ti alloy with grain size ranging from 10 to 70 nm and nearly full density is consolidated in 2 seconds. The novel consolidation approach proposed here offers a general and highly efficient pathway for manufacturing bulk nanomaterials

Strain-restricted transfer of ferromagnetic electrodes for constructing reproducibly superior-quality spintronic devices

Spintronic device is the fundamental platform for spin-related academic and practical studies. However, conventional techniques with energetic deposition or boorish transfer of ferromagnetic metal inevitably introduce uncontrollable damage and undesired contamination in various spin-transport-channel materials, leading to partially attenuated and widely distributed spintronic device performances. These issues will eventually confuse the conclusions of academic studies and limit the practical applications of spintronics. Here we propose a polymer-assistant strain-restricted transfer technique that allows perfectly transferring the pre-patterned ferromagnetic electrodes onto channel materials without any damage and change on the properties of magnetism, interface, and channel. This technique is found productive for pursuing superior-quality spintronic devices with high controllability and reproducibility. It can also apply to various-kind (organic, inorganic, organic-inorganic hybrid, or carbon-based) and diverse-morphology (smooth, rough, even discontinuous) channel materials. This technique can be very useful for reliable device construction and will facilitate the technological transition of spintronic study

A Study on the English Translation on Chapter Two of Tao Te Ching from the Perspective of Eco-Translatology: Lin Yutang’s and James Legge's Versions

Chu Culture includes material civilization and spiritual civilization created by Chu people in their working life, and it is an important part of Chinese civilization. Besides Lisao and Tianwen, Tao Te Ching by Lao Tzu is also deeply influenced by Chu culture. Under the guidance of eco-translation theory, this paper takes Chapter two of Tao Te Ching as an example, selects Lin Yutang’s and James Legge’s translations as the research objects, and analyzes them from the perspectives of language, culture and communication, respectively. The purpose is to explore whether the eco-translation theory can apply to the previous English translations of Tao Te Ching, and to further understand the implicit relationship between Chu culture and Tao Te Ching

Investigation of the Microstructures of Graphene Quantum Dots (GQDs) by Surface-Enhanced Raman Spectroscopy

Photoluminescence (PL) is the most significant feature of graphene quantum dots (GQDs). However, the PL mechanism in GQDs has been debated due to the fact that the microstructures, such as edge and in-plane defects that are critical for PL emission, have not been convincingly identified due to the lack of effective detection methods. Conventional measures such as high-resolution transmission electron microscopy and infrared spectroscopy only show some localized lattice fringes of GQDs and the structures of some substituents, which have little significance in terms of thoroughly understanding the PL effect. Here, surface-enhanced Raman spectroscopy (SERS) was introduced as a highly sensitive surface technique to study the microstructures of GQDs. Pure GQDs were prepared by laser ablating and cutting highly oriented pyrolytic graphite (HOPG) parallel to the graphite layers. Consequently, abundant SERS signals of the GQDs were obtained on an Ag electrode in an electrochemical environment for the first time. The results convincingly and experimentally characterized the typical and detailed features of GQDs, such as the crystallinity of sp2 hexagons, the quantum confinement effect, various defects on the edges, sp3-like defects and disorders on the basal planes, and passivated structures on the periphery and surface of the GQDs. This work demonstrates that SERS is thus by far the most effective technique for probing the microstructures of GQDs

A cross‐layer anti‐jamming method in satellite Internet

Abstract In view of the diverse jamming environment, the single‐level anti‐jamming method faces some challenges such as poor timeliness, high cost and poor effect. In this paper, routing delay, cost overhead and diversified jamming threats are comprehensively considered. In addition, a cross‐layer anti‐jamming method is proposed in the scenario of busy satellite Internet communication. The proposed cross‐layer anti‐jamming method involves two levels: link‐layer anti‐jamming based on path repair and network‐layer anti‐jamming based on path reconstruction. On the one hand, the channel is selected based on the improved Q‐learning anti‐jamming algorithm to confront common jamming. On the other hand, the route from the source to the destination node is selected based on the cross‐layer anti‐jamming algorithm to confront high‐intensity jamming. Finally, the simulation results show that, compared with other anti‐jamming algorithms, the proposed algorithm can achieve higher efficiency, lower cost, and more robust anti‐jamming routing

Insight into the Roles of Ammonia during Direct Alcohol Amination over Supported Ru Catalysts

10.1016/j.jcat.2021.05.002Journal of Catalysi

Study on properties of high strength steel during warm roll forming

Roll forming is a 3D deformation complex process.Stiffness of stands and strength of shafts are the preconditions for the production of precision products.However, the existing roll forming equipment cannot meet the requirements of the production for high strength steel or ultra high strength steel.In order to solve the forming problem of high strength steel or ultra high strength steel, it needs to redesign a set of roll forming equipment.The redesign of roll forming equipment not only makes the production cycle too long, but also results in a high cost.So it is not suitable for the production of forming products.In this paper, based on the existing roll forming equipment a new method of roll forming operation is proposed to optimize the production of U shaped products.The influences of the new method on the roll forming products such as mechanical properties, microstructures and surface qualities, have also been discussed, Based on the new warm roll forming operation, numerical simulation has also been carried out.The simulation result of geometry is in good agreement with experimental result