亚微米尺寸、高结晶度石墨烯增强间位芳纶纤维力学性能

芳纶纤维具有优异的综合性能,在各种工业应用中备受青睐。其中,间位芳纶纤维,也称聚间苯二甲酰间苯二胺(PMIA)纤维,兼具阻燃、耐高温、电隔离和高化学稳定性。其织物材料广泛应用于防火、防热等行业。然而,由于分子链中酰胺和苯环键之间缺乏偶联,内旋能低,导致PMIA纤维链段柔软、结晶度低,展现出较低的机械强度。因此,迫切需要改善这些纤维的机械特性,以扩大其应用范围。纳米复合材料的可以赋予基体材料许多独特特性。其中,石墨烯纳米复合材料占据突出地位。石墨烯面内的苯环结构使其可以有效增强芳香族和脂肪族类聚合物材料。此外,与大尺寸的石墨烯相比,小尺寸的石墨烯在聚合物基体中表现出更好的分散性,可在纤维类聚合物材料中展现出更明显的增强效应。因此,使用高品质、小尺寸的石墨烯是增强聚合物基体的有效手段。我们的研究展示了亚微米尺寸的石墨烯如何改善PMIA纤维的结构完整性和增加机械强度。结果显示,与未改性的PMIA纤维相比,拉伸强度显著提高46%。鉴于该方法的有效性,可以采用此种“小尺寸、高品质”的石墨烯来开发更强韧且更具商用价值的碳基纳米复合纤维。

In vivo evaluation of additively manufacturedmulti-layered scaffold for the repair of large osteochondral defects

The repair of osteochondral defects is one of the major clinical challenges in orthopaedics.Well-established osteochondral tissue engineering methods have shown promising results for the early treatment of small defects.However,less success has been achieved for the regeneration of large defects,which is mainly due to the mechanical environment of the joint and the heterogeneous nature of the tissue.In this study,we developed a multi-layered osteochondral scaffold to match the heterogeneous nature of osteochondral tissue by harnessing additive manufacturing technologies and combining the established art laser sintering and material extrusion techniques.The developed scaffold is based on a titanium and polylactic acid matrix-reinforced collagen“sandwich”composite system.The microstructure and mechanical properties of the scaffold were examined,and its safety and efficacy in the repair of large osteochondral defects were tested in an ovine condyle model.The 12-week in vivo evaluation period revealed extensive and significantly higher bone in-growth in the multi-layered scaffold compared with the collagen–HAp scaffold,and the achieved stable mechanical fixation provided strong support to the healing of the overlying cartilage,as demonstrated by hyaline-like cartilage formation.The histological examination showed that the regenerated cartilage in the multi-layer scaffold group was superior to that formed in the control group.Chondrogenic genes such as aggrecan and collagen-II were upregulated in the scaffold and were higher than those in the control group.The findings showed the safety and efficacy of the cell-free“translation-ready”osteochondral scaffold,which has the potential to be used in a one-step surgical procedure for the treatment of large osteochondral defects.

Solution-Processed Hybrid Europium (Ⅱ) lodide Scintillator for Sensitive X-Ray Detection

Lead halide perovskite nanocrystals have recently demonstrated great potential as x-ray scintillators,yet they stll suffer toxicity issues,inferior light yield(LY)caused by severe self-absorption.Nontoxic bivalent europium ions(Eu^(2+))with intrinsically efficient and self-absorption-free d-f transition are a prospective replacement for the toxic Pb^(2+).Here,we demonstrated solution-processed organic-inorganic hybrid halide BA_(10)Eul_(12)(BA denotes C_(4)H_(9)NH_(4)^(+))single crystals for the first time.

Antimony doped Cs2SnCl6 with bright and stable emission

Lead halide perovskites,with high photoluminescence efficiency and narrow・band emission,are promising materials for display and lighting.However,the lead toxicity and environmental sensitivity hinder their potential applications.Herein,a new antimony・doped lead-free inorganic perovskites variant Cs2SnCl6:xSb is designed and synthesized.The perovskite variant Cs2SnCl6:xSb exhibits a broadband orange-red emission,with a photoluminescence quantum yield(PLQY)of 37%.The photoluminescence of Cs2SnCl6:xSb is caused by the ionoluminescence of Sb3+within Cs2SnCl6 matrix,which is verified by temperature dependent photoluminescence(PL)and PL decay measurements.In addition,the all inorganic structure renders Cs2SnCl6:xSb with excellent thermal and water stability.Finally,a white light-emitting diode(white-LED)is fabricated by assembling Cs2SnCl6:0.59%Sb,Cs2SnCl6:2.75%Bi and Ba2Sr2SiO4:Eu2+onto the commercial UV LED chips,and the color rendering index(CRI)reaches 81.

The influence of nanotopography on cell behaviour through interactions with the extracellular matrix-A review

Nanotopography presents an effective physical approach for biomaterial cell manipulation mediated through material-extracellular matrix interactions.The extracellular matrix that exists in the cellular microenvironment is crucial for guiding cell behaviours,such as determination of integrin ligation and interaction with growth factors.These interactions with the extracellular matrix regulate downstream mechanotransductive pathways,such as rearrangements in the cytoskeleton and activation of signal cascades.Protein adsorption onto nanotopography strongly influences the conformation and distribution density of extracellular matrix and,therefore,subsequent cell responses.In this review,we first discuss the interactive mechanisms of protein physical adsorption on nanotopography.Secondly,we summarise advances in creating nanotopographical features to instruct desired cell behaviours.Lastly,we focus on the cellular mechanotransductive pathways initiated by nanotopography.This review provides an overview of the current state-of-the-art designs of nanotopography aiming to provide better biomedical materials for the future.

All-vacuum fabrication of yellow perovskite light-emitting diodes

Yellow light-emitting diodes(LEDs) are widely utilized in high-quality lighting, light communication,indicator lamps, etc. Owing to their outstanding material properties and device performance, the metal halide perovskites have demonstrated a significant potential for LED applications. However, the performance of the yellow perovskite LEDs(PeLEDs) is inferior to that of their green and red counterparts, with the maximum external quantum efficiency(EQE) limited to ~3.1%. Further, a majority of the yellow PeLEDs are fabricated using the spin-coating methods. The current study reports the development of the yellow CsPbBr_(2)I PeLEDs based on an all-vacuum deposition approach, which has been widely employed in the commercial organic LEDs(OLEDs). By controlling the co-evaporation rate of CsI and PbBr;, the growth kinetics of the perovskite layer are regulated to achieve a small grain size of~31.8 nm. Consequently, an improved radiative recombination rate(8.04 × 10^(-9)cm^(3)/s) is obtained owing to the spatial confinement effect. The PeLEDs based on the optimal perovskite film demonstrate the yellow electroluminescence(574 nm) with a maximum EQE of ~3.7% and luminance of~16,200 cd/m^(2), thus, representing one of the most efficient and bright yellow PeLEDs. Overall, this study provides a useful guideline for realizing the efficient PeLEDs based on the thermal evaporation strategy and highlights the potential of PeLED as an efficient and bright yellow light source.

Organic–inorganic hybrid perovskite scintillators for mixed field radiation detection

Sensitive and fast detection of neutrons and gamma rays is vital for homeland security,high-energy physics,and proton therapy.Fast-neutron detectors rely on light organic scintillators,andγ-ray detectors use heavy inorganic scintillators and semiconductors.Efficient mixed-field detection using a single material is highly challenging due to their contradictory requirements.Here we report hybrid perovskites(C_(8)H_(12)N)_(2)Pb(Br_(0.95)Cl_(0.05))_(4)that combine light organic cations and heavy inorganic skeletons at a molecular level to achieve unprecedented performance for mixed-field radiation detection.High neutron absorption due to a high density of hydrogen,strong radiative recombination within the highly confined[PbX_(6)]^(4-)layer,and sub-nanometer distance between absorption sites and radiative centers,enable a light yield of 41000 photons/MeV,detection pulse width of 2.97 ns and extraordinary linearity response toward both fast neutrons andγ-rays,outperforming commonly used fast-neutron scintillators.Neutron energy spectrum,time-of-flight based fast-neutron/γ-ray discrimination and neutron yield monitoring were all successfully achieved using(C_(8)H_(12)N)_(2)Pb(Br_(0.95)Cl_(0.05))_(4)detectors.We further demonstrate the monitoring of reaction kinetics and total power of a nuclear fusion reaction.We envision that molecular hybridized scintillators open a new avenue for mixed-field radiation detection and imaging.

Improving the fretting biocorrosion of Ti6Al4V alloy bone screw by decorating structure optimised TiO2 nanotubes layer

TiO2 nanotubes(NT)has been demonstrated its potential in orthopaedic applications due to its enhanced surface wettability and bio-osteointegration.However,the fretting biocorrosion is the main concern that limited its successfully application in orthopaedic application.In this study,a structure optimised thin TiO2 nanotube(SONT)layer was successfully created on Ti6Al4V bone screw,and its fretting corrosion performance was investigated and compared to the pristine Ti6Al4V bone screws and NT decorated screw in a bone-screw fretting simulation rig.The results have shown that the debonding TiO2 nanotube from the bone screw reduced significantly,as a result of structure optimisation.The SONT layer also exhibited enhanced bio-corrosion resistance compared pristine bone screw and conventionally NT modified bone screw.It is postulated that interfacial layer between TiO2 nanotube and Ti6Al4V substrate,generated during structure optimisation process,enhanced bonding of TiO2 nanotube layer to the Ti6Al4V bone screws that leading to the improvement in fretting corrosion resistance.The results highlighted the potential SONT in orthopaedic application as bone fracture fixation devices.

Growth of TiO2 Nanotube on Titanium Substrate to Enhance its Biotribological Performance and Biocorrosion Resistance

TiO2 nanotubes(NTs)have a great potential in improving the osetointegration of titanium(Ti)-based biomaterials.Much efforts have been made to evaluate the biological performance of the TiO2 nanotube in regulating protein adsorption and cells attachments.As often used in orthopaedic applications,although biotribological performance and biocorrosion are important issues in these applications,few researches have been reported on the biotribological perfonnance of NT layers.This paper reports the preparation of a structure-optimised TiO2 NT(SO-NT)material via a multi-step oxidation strategy,as well as its biotribological and biocorrosion behaviours.In this procedure,an interfacial bonding layer of approximately 120 nm=150 nm was first formed on the titanium substrate,which was then joined to the NT bottoms.The mechanical testing with respect to impact,bending,and biotribological perfbnnance have demonstrated the resultant SO-NT layer possess improved mechanical stability compared to conventional NT.The uniform hyperfine interfacial bonding layer with nano-sized grains exhibited a strong bonding to NT layer and Ti substrate.It was observed that the layer not only effectively dissipates external impacts and shear stress but also acts as a good corrosion resistance barrier to prevent the Ti substrate from corrosion.Theoretical models were proposed to analyze and predict the shear performance and corrosion-resistance mechanisms of the resultant material.The obtained results demonstrated that the SO-NT material has great potential in orthopaedic applications.

Single-event burnout hardening of planar power MOSFET with partially widened trench source

We present a single-event burnout（SEB） hardened planar power MOSFET with partially widened trench sources by three-dimensional（3 D） numerical simulation. The advantage of the proposed structure is that the work of the parasitic bipolar transistor inherited in the power MOSFET is suppressed effectively due to the elimination of the most sensitive region（P-well region below the N＋ source）. The simulation result shows that the proposed structure can enhance the SEB survivability significantly. The critical value of linear energy transfer（LET）,which indicates the maximum deposited energy on the device without SEB behavior, increases from 0.06 to0.7 p C/μm. The SEB threshold voltage increases to 120 V, which is 80% of the rated breakdown voltage. Meanwhile, the main parameter characteristics of the proposed structure remain similar with those of the conventional planar structure. Therefore, this structure offers a potential optimization path to planar power MOSFET with high SEB survivability for space and atmospheric applications.

Synthesis of [2,2’]Bifuranyl-5,5’-dicarboxylic Acid Esters Wd Reductive Homocoupling of 5-Bromofuran-2-carboxylates Using Alcohols as Reductants

Herein,we describe an environmentally benign and cost.efective protocol for the synthesis of valuable bifuranyl dicarboylates,starting with a-bromination of readily accessible furan-2-carboylates by LiBr and K_(2)S_(2)O_(8).Furthermore,the bromination intermediate product 5-bromofuran-2-carboxylates were then conducted in a palladium-catalyzed reductive homocoupling reactions in the pres-ence of alcohols to afford bifuranyl dicarboxylates.One of the final products in this protocol,[2,2']bifuran-5,5'-dicarboxylic acid es-ters,are essential monomers of poly(ethylene bifuranoate),which can be served as an green and versatile alternative polymer for traditional poly(ethylene terephthalate)that is currently common in technical plastics.

Oxide perovskite Ba_(2)AgIO_(6)wafers for X-ray detection

X-ray detection is of great significance in biomedical,nondestructive,and scientific research.Lead halide perovskites have recently emerged as one of the most promising materials for direct X-ray detection.However,the lead toxicity remains a worrisome concern for further commercial application.Great efforts have been made to search for lead-free perovskites with similar optoelectronic properties.Here,we present a lead-free oxide double perovskite material Ba2AgIO6 for X-ray detection.The lead-free,all-inorganic nature,as well as the high density of Ba2AgIO6,promises excellent prospects in X-ray applications.By employing the hydrothermal method,we successfully synthesized highly crystalline Ba2AgIO6 powder with pure phase.Furthermore,we prepared Ba2AgIO6 wafers through isostatic pressure and built X-ray detectors with Au/Ba2AgIO6 wafer/Au photoconductive structure.The as-prepared X-ray detectors showed a sensitivity of 18.9μC/(Gyair$cm2)at 5 V/mm,similar to commercialα-Se detectors showcasing their advantages for X-ray detection.

Fretting corrosion of screws contribute to the fixation failure of the femoral neck:a case report

Fretting corrosion of metal implants has been associated with implant failure and revision surgeries.This report describes the fixation failure of a femoral neck fracture in a 61-year-old male patient due to corrosion of three cannulated screws.Radiographic evaluation at the time of primary surgery demonstrated well-positioning of the cannulated screws.The patient had no significant medical comorbidities at the time of surgery.However,screw loosening and avascular necrosis were diagnosed after 5 years.At the revision surgery,inflammatory serological markers,C-reactive protein and erythrocyte sedimentation rate showed no signs of infections,and screws were retrieved.Scanning electron microscopy observations showed that all screws were subjected to fretting corrosion which led to discolouration,pitting attack,and cracking.Thus,Fretting corrosion may have contributed to the failure of the fixation of screws.