Jiangsu University of Science and Technology

Compared with stainless steel and Co–Cr‐based alloys, Ti and its alloys are widely used as biomedical implants due to many fascinating properties, such as superior mechanical properties, strong corrosion resistance, and excellent biocompatibility. After briefly introducing several most commonly used biomedical materials, this article reviews the recent development in Ti alloys and their biomedical applications, especially the low‐modulus β ‐type Ti alloys and their design methods. This review also systemically investigates the recently attractive progress in preparation of biomedical Ti alloys, including additive manufacturing, porous powder metallurgy, and severe plastic deformation, applied in the manufacturing and the influenced microstructures and properties. Nevertheless, there are still some problems with the long‐term performance of Ti alloys, and therefore several surface modification methods are reviewed to further improve their biological activity, wear resistance, and corrosion resistance. Finally, the biocompatibility of Ti and its alloys is concluded. Summarizing the findings from literature, future prediction is also conducted.

Silk fibroin from the silkworm, Bombyx mori, has excellent properties such as biocompatibility, biodegradation, non-toxicity, adsorption properties, etc. As a kind of ideal biomaterial, silk fibroin has been widely used since it was first utilized for sutures a long time ago. The degradation behavior of silk biomaterials is obviously important for medical applications. This article will focus on silk-based biomaterials and review the degradation behaviors of silk materials.

Electrically conductive polymer composite-based smart strain sensors with different conductive fillers, phase morphology, and imperative features were reviewed.

Purpose – The aim of this paper is to investigate the impact of knowledge sharing (KS) on firm performance and the mediating role of intellectual capital (IC). Design/methodology/approach – A research model was developed based on prior KS and IC studies. A survey was administered to a sample of high technology firms in China and 228 usable responses were collected. Structural equation modeling (SEM) was employed to test the research model. Findings – Tacit KS significantly was found to contribute to all three components of IC, namely human, structural and relational capital, while explicit KS only has a significant influence on human and structural capital. Human, structural and relational capital, enhance both operational and financial performance of firms. The effect of KS on firm performance is mediated by IC. Explicit KS has a greater effect on financial performance than operational performance, whereas tacit KS has a greater impact on operational performance than financial performance. Research limitations/implications – The sample of high technology firms in China might limit the generalization of the findings. Nonetheless, this study takes its lead from and extends prior research, thus providing a deepened understanding of the role of KS in organizational settings. Practical implications – The paper suggests that managers can enhance firm performance by enhancing their KS and IC. Managers can develop corresponding strategies based on the findings to achieve their specific performance goals. Originality/value – This is one of the first papers to examine how KS contributes to firm performance through the mediation of IC. It will add significant value for organizations trying to enhance their performance though KS practices.

Magnetic carbon nanofibers containing uniformly dispersed Fe/Co/Ni nanoparticles (CNF–M) exhibit excellent electromagnetic wave absorption properties from the C-band to the Ku-band.

Systematic insights into the recent attainments, limitations, and future directions of hydrogen production, storage, delivery, and usage are provided, aiming at offering critical guidance for the future establishment of a hydrogen society.

Highly conductive and stretchable electrospun thermoplastic polyurethane yarns with multi-walled and single-walled CNTs were prepared.

Thanks to a considerable number of fascinating properties, titanium (Ti) and Ti alloys play important roles in a variety of industrial sectors. However, Ti and Ti alloys could not satisfy all industrial requirements; the degradation of Ti and Ti alloys always commences on their surfaces in service, which declines the performances of Ti workpieces. Therefore, with aim to further improve their mechanical, corrosion and biological properties, surface modification is often required for Ti and Ti alloys. This article reviews the technologies and recent developments of surface‐modification methods with respect to Ti and Ti alloys, including mechanical, physical, chemical, and biochemical technologies. Conventional methods have limited improvement in the properties and/or restriction on the geometry of workpieces. Therefore, many advanced surface‐modification technologies have emerged in recent decades. New methods make Ti and Ti alloys have better performance and extended applications. With requirement of high surface properties in future. Understanding the mechanism in various surface‐modification methods, combining the advantages of current technologies and developing new coating materials with high performance are required urgently. As such, incorporation of different surface‐modification technologies with high‐performance modified layers may be the mainstream of surface modifications for Ti and Ti alloys.

Developing high‐efficiency and low‐cost photocatalysts by avoiding expensive noble metals, yet remarkably improving H 2 evolution performance, is a great challenge. Noble‐metal‐free catalysts containing Co(Fe)NC moieties have been widely reported in recent years for electrochemical oxygen reduction reaction and have also gained noticeable interest for organic transformation. However, to date, no prior studies are available in the literature about the activity of N‐coordinated metal centers for photocatalytic H 2 evolution. Herein, a new photocatalyst containing g‐C 3 N 4 decorated with CoP nanodots constructed from low‐cost precursors is reported. It is for the first time revealed that the unique P(δ − )Co(δ + )N(δ − ) surface bonding states lead to much superior H 2 evolution activity (96.2 µmol h −1 ) compared to noble metal (Pt)‐decorated g‐C 3 N 4 photocatalyst (32.3 µmol h −1 ). The quantum efficiency of 12.4% at 420 nm is also much higher than the record values (≈2%) of other transition metal cocatalysts‐loaded g‐C 3 N 4 . It is believed that this work marks an important step toward developing high‐performance and low‐cost photocatalytic materials for H 2 evolution.

Ammonia (NH₃), one of the basic chemicals in most fertilizers and a promising carbon-free energy storage carrier, is typically synthesized via the Haber–Bosch process with high energy consumption and massive emission of greenhouse gases. The photo/electrocatalytic nitrogen reduction reaction (NRR) under ambient conditions has attracted increasing interests recently, providing alternative routes to realize green NH₃ synthesis. Despite rapid advances achieved in this most attractive research field, the unsatisfactory conversion efficiency including a low NH₃ yield rate, and limited Faradaic efficiency or apparent quantum efficiency still remains as a great challenge. The NRR performance is intrinsically related to the electronic and surface structure of catalysts. Rational design and preparation of advanced catalysts are indispensable to improve the performance (e.g., activity and selectivity) of NRR. In this Review, various strategies for the development of desirable catalysts are comprehensively summarized, mainly containing the defect engineering, structural manipulation, crystallographic tailoring, and interface regulation. State-of-the-art heterogeneous NRR catalysts, prevailing theories and underlying catalytic mechanisms, together with current issues, critical challenges, and perspectives are discussed. It is highly expected that this Review will promote the understanding of recent advances in this area and stimulate greater interests for designing promising NRR catalysts in future.

This review paper summarizes the categories, sensing mechanisms, and affecting factors of flexible conductive polymer composite-based stretchable strain sensors.

Cobalt sulfide materials have attracted enormous interest as low‐cost alternatives to noble‐metal catalysts capable of catalyzing both oxygen reduction and oxygen evolution reactions. Although recent advances have been achieved in the development of various cobalt sulfide composites to expedite their oxygen reduction reaction properties, to improve their poor oxygen evolution reaction (OER) activity is still challenging, which significantly limits their utilization. Here, the synthesis of Fe 3 O 4 ‐decorated Co 9 S 8 nanoparticles in situ grown on a reduced graphene oxide surface (Fe 3 O 4 @Co 9 S 8 /rGO) and the use of it as a remarkably active and stable OER catalyst are first reported. Loading of Fe 3 O 4 on cobalt sulfide induces the formation of pure phase Co 9 S 8 and highly improves the catalytic activity for OER. The composite exhibits superior OER performance with a small overpotential of 0.34 V at the current density of 10 mA cm −2 and high stability. It is believed that the electron transfer trend from Fe species to Co 9 S 8 promotes the breaking of the Co–O bond in the stable configuration (Co–O–O superoxo group), attributing to the excellent catalytic activity. This development offers a new and effective cobalt sulfide‐based oxygen evolution electrocatalysts to replace the expensive commercial catalysts such as RuO 2 or IrO 2 .

Lead-free piezoelectric materials and innovative piezoelectric devices provide a solution to the energy and environmental crisis we are now faced with.

Abstract The functionalized conductive polymer is a promising choice for flexible triboelectric nanogenerators (TENGs) for harvesting human motion energy still poses challenges. In this work, a transparent and stretchable wrinkled poly(3,4‐ethylenedioxythiophene):poly(4‐styrenesulfonate) (PEDOT:PSS) electrode based TENG (WP‐TENG) is fabricated. The optimum conductivity and transparency of PEDOT:PSS electrode can reach 0.14 kΩ □ −1 and 90%, respectively, with maximum strain of ≈100%. Operating in single‐electrode mode at 2.5 Hz, the WP‐TENG with an area of 6 × 3 cm 2 produces an open‐circuit voltage of 180 V, short‐circuit current of 22.6 µA, and average power density of 4.06 mW m −2 . It can be worn on the wrist to harvest hand tapping energy and charge the capacitor to 2 V in ≈3.5 min, and then drive an electronic watch. Furthermore, the WP‐TENG as the human motion monitoring sensor could inspect the bending angle of the elbow and joint by analyzing the peak value of voltage and monitor the motion frequency by counting the peak number. The triboelectric mechanism also enables the WP‐TENG to realize high‐performance active tactile sensing. The assembled 3 pixel × 3 pixel tactile sensor array is fabricated for mapping the touch location or recording the shape of object contacted with the sensor array.

Co–Zn/N–C polyhedral nanocages: porous bimetallic Co/Zn embedded N-doped carbon (Co–Zn/N–C) polyhedral nanocages have been synthesized through annealing a ZIF-8@ZIF-67 precursor for the first time. The excellent lithium-storage ability is attributed to the unique structure of Co–Zn/N–C.

Internet forums and public social media, such as online healthcare forums, provide a convenient channel for users (people/patients) concerned about health issues to discuss and share information with each other. In late December 2019, an outbreak of a novel coronavirus (infection from which results in the disease named COVID-19) was reported, and, due to the rapid spread of the virus in other parts of the world, the World Health Organization declared a state of emergency. In this paper, we used automated extraction of COVID-19-related discussions from social media and a natural language process (NLP) method based on topic modeling to uncover various issues related to COVID-19 from public opinions. Moreover, we also investigate how to use LSTM recurrent neural network for sentiment classification of COVID-19 comments. Our findings shed light on the importance of using public opinions and suitable computational techniques to understand issues surrounding COVID-19 and to guide related decision-making. In addition, experiments demonstrated that the research model achieved an accuracy of 81.15% - a higher accuracy than that of several other well-known machine-learning algorithms for COVID-19-Sentiment Classification.

Abstract Solar-driven hydrogen peroxide (H 2 O 2 ) production presents unique merits of sustainability and environmental friendliness. Herein, efficient solar-driven H 2 O 2 production through dioxygen reduction is achieved by employing polymeric carbon nitride framework with sodium cyanaminate moiety, affording a H 2 O 2 production rate of 18.7 μmol h −1 mg −1 and an apparent quantum yield of 27.6% at 380 nm. The overall photocatalytic transformation process is systematically analyzed, and some previously unknown structural features and interactions are substantiated via experimental and theoretical methods. The structural features of cyanamino group and pyridinic nitrogen-coordinated soidum in the framework promote photon absorption, alter the energy landscape of the framework and improve charge separation efficiency, enhance surface adsorption of dioxygen, and create selective 2e − oxygen reduction reaction surface-active sites. Particularly, an electronic coupling interaction between O 2 and surface, which boosts the population and prolongs the lifetime of the active shallow-trapped electrons, is experimentally substantiated.

Nickel selenide (NiSe) nanoparticles uniformly supported on graphene nanosheets (G) to form NiSe-G nanohybrids were prepared by an in situ hydrothermal process. The uniform distribution of NiSe on graphene bestowed the NiSe-G nanohybrid with faster charge transport and diffusion along with abundant accessible electrochemical active sites. The synergistic effect between NiSe nanoparticles and graphene nanosheets for supercapacitor applications was systematically investigated for the first time. The freestanding NiSe-G nanohybrid electrode exhibited better electrochemical performance with a high specific capacitance of 1280 F g-1 at a current density of 1 A g-1 and a capacitance retention of 98% after 2500 cycles relative to that of NiSe nanoparticles. Furthermore, an asymmetric supercapacitor device assembled using the NiSe-G nanohybrid as the positive electrode, activated carbon as the negative electrode and an electrospun PVdF membrane containing 6 M KOH as both the separator and the electrolyte delivered a high energy density of 50.1 W h kg-1 and a power density of 816 W kg-1 at an extended operating voltage of 1.6 V. Thus, the NiSe-G nanohybrid can be used as a potential electrode material for high-performance supercapacitors.

After optimization using percolation theory, excellent absorbing properties (90% absorption) were achieved for Ni/C nanocomposites with advantages such as thin thickness (1.75 and 1.5 mm) and light weight (25 and 30 wt%).

Design of an interface to arouse interface polarization is an efficient route to attenuate high-frequency electromagnetic waves. The attenuation intensity is highly related to the contact area. To achieve stronger interface polarization, growing metal oxide granular film on graphene with a larger surface area seems to be an efficient strategy due to the high charge carrier concentration of graphene. This study is devoted to fabricating the filmlike composite by a facile thermal decomposition method and investigating the relationship among contact area, polarization intensity, and the type of metal oxide. Because of the high-frequency polarization effect, the composites presented excellent electromagnetic wave attenuation ability. It is shown that the optimal effective frequency bandwidth of graphene/metal oxide was close to 7.0 GHz at a thin coating layer of 2.0 mm. The corresponding reflection loss value was nearly -22.1 dB. Considering the attenuation mechanism, interface polarization may play a key role in the microwave-absorbing ability.