Recent advances in cardiovascular stent for treatment of in-stent restenosis:Mechanisms and strategies

Treatments of atherogenesis,one of the most common cardiovascular diseases(CVD),are continuously being made thanks to innovation and an increasingly in-depth knowledge of percutaneous transluminal coronary angioplasty(PTCA),the most revolutionary medical procedure used for vascular restoration.Combined with an expanding balloon,vascular stents used at stricture sites enable the long-time restoration of vascular permeability.However,complication after stenting,in-stent restenosis(ISR),hinders the advancement of vascular stents and are associated with high medical costs for patients for decades years.Thus,the development of a high biocompatibility stent with improved safety and efficiency is urgently needed.This review provides an overview of current advances and potential technologies for the modification of stents for better treatment and prevention of ISR.In particular,the mechanisms of in-stent restenosis are investigated and summarized with the aim to comprehensively understanding the pathogenesis of stent complications.Then,according to different therapeutic functions,the current stent modification strategies are reviewed,including polymeric drug eluting stents,biological friendly stents,prohealing stents,and gene stents.Finally,the review provides an outlook of the challenges in the design of stents with optimal properties.Therefore,this review is a valuable and practical guideline for the development of cardiovascular stents.

Effects of interfacial discontinuity on the fracture behavior in the superconductor-substrate system

This study concerns a two-dimensional model and the corresponding virtual crack closure technique(VCCT) implemented to solve the general boundary value problems that may explain why interface discontinuity has effects on the fracture behavior in the superconductor-substrate system. The interfacial discontinuity can be classified according to the material properties' continuity and their derivatives' continuity at the interface. For nonhomogeneous superconductor and substrate specimens with various material properties, a VCCT method is developed to calculate their fracture behavior. Furthermore, the effects of applied magnetic field amplitude and nonhomogeneous parameters are extensively and parametrically studied in two activation processes(zero-field cooling and field cooling). The integrative and computational study presented here provide a fundamental mechanistic understanding of the fracture mechanism in the superconductor-substrate system and sheds light on the rational design of interfacial continuity.

Solution-Processed Monolayer Molecular Crystals:From Precise Preparation to Advanced Applications

Emerging monolayer molecular crystals(MMCs)have become prosperous in recent decades due to their numerous advantages.First,downsizing the active layer thickness to monolayer in organic field-effect transistors(OFETs)is beneficial to elucidate the intrinsic charge-transport behavior.Next,the ultrathin conducting channel can reduce bulk injection resistance to extract mobility accurately.Then,direct exposure of the conducting channel can enhance the sensing performance.Finally,MMCs combine the merits of ultrathin thickness and high crystallization,which will improve the optoelectronic performance and realize complex device architectures for future advanced optoelectronic applications.In this Review,recent research progress in precise preparations and advanced applications of solution-processed MMCs are summarized.We present the current challenges related to MMCs with specific structures and desired performances,and an outlook regarding their application in next-generation integrated organic optoelectronics is provided.

Interfacial mechanism of hydrogel with controllable thickness for stable drag reduction

Surface wettability plays a significant role in reducing solid–liquid frictional resistance,especially the superhydrophilic/hydrophilic interface because of its excellent thermodynamic stability.In this work,poly(acrylic acid)-poly(acrylamide)(PAA–PAM)hydrogel coatings with different thicknesses were prepared in situ by polydopamine(PDA)-UV assisted surface catalytically initiated radical polymerization.Fluid drag reduction performance of hydrogel surface was measured using a rotational rheometer by the plate–plate mode.The experimental results showed that the average drag reduction of hydrogel surface could reach up to about 56%in Couette flow,which was mainly due to the interfacial polymerization phenomenon that enhanced the ability of hydration layer to delay the momentum dissipation between fluid layers and the diffusion behavior of surface.The proposed drag reduction mechanism of hydrogel surface was expected to shed new light on hydrogel–liquid interface interaction and provide a new way for the development of steady-state drag reduction methods.

Enhanced charge transport in 2D inorganic molecular crystals constructed with charge-delocalized molecules

Outstanding charge transport in molecular crystals is of great importance in modern electronics and optoelectronics.The widely adopted strategies to enhance charge transport,such as restraining intermolecular vibration,are mostly limited to organic molecules,which are nearly inoperative in 2D inor-ganic molecular crystals currently.In this contribution,charge transport in 2D inorganic molecular crystals is improved by integrating charge-delocalized Se8 rings as building blocks,where the delocalized electrons on Se8 rings lift the intermolecular orbitals overlap,offering efficient charge transfer channels.Besides,α-Se flakes composed of charge-delocalized Se8 rings possess small exciton binding energy.Benefitting from these,α-Se flake exhibits excellent photodetection performance with an ultrafast response rate(�5μs)and a high detectivity of 1.08�1011 Jones.These findings contribute to a deeper under-standing of the charge transport of 2D inorganic molecular crystals composed of electron-delocalized inorganic molecules and pave the way for their poten-tial application in optoelectronics.

Monolayer organic field-effect transistors

Monolayer organic field-effect transistors(OFETs) are attracting worldwide interest in device physics and novel applications due to their ultrathin active layer for two-dimensional charge transport. The monolayer films are generally prepared by thermal evaporation, the Langmuir technique or self-assembly process, etc., but their electrical performance is relatively lower than corresponding thick films. From 2011, the performance of monolayer OFETs has been boosted by using the monolayer molecular crystals(MMCs) as active channels, which opened up a new era for monolayer OFETs. In this review, recent progress of monolayer OFETs, including the preparation of monolayer films, their OFET performance and applications are summarized.Finally, perspectives of monolayer OFETs in the near future are also discussed.

Amorphous B-doped graphitic carbon nitride quantum dots with high photoluminescence quantum yield of near 90% and their sensitive detection of Fe^(2+)/Cd^(2+)

Graphitic carbon nitride quantum dots(CNQDs) are emerging as attractive photoluminescent(PL)materials with excellent application potential in fluorescence imaging and heavy-metal ion detection. However, three limitations, namely, low quantum yields(QYs), self-quenching,and excitation-dependent PL emission behaviors, severely impede the commercial applications of crystalline CNQDs.Here we address these three challenges by synthesizing borondoped amorphous CNQDs via a hydrothermal process followed by the top±down cutting approach. Structural disorder endows the amorphous boron-doped CNQDs(B-CNQDs)with superior elastic strain performance over a wide range of pH values, thus effectively promoting mass transport and reducing exciton quenching. Boron as a dopant could fine-tune the electronic structure and emission properties of the PL material to achieve excitation-independent emission via the formation of uniform boron states. As a result, the amorphous B-CNQDs show unprecedented fluorescent stability(i.e., no obvious fading after two years) and a high QY of 87.4%;these values indicate that the quantum dots obtained are very promising fluorescent materials. Moreover, the B-CNQDs show bright-blue fluorescence under ultraviolet excitation when applied as ink on commercially available paper and are capable of the selective and sensitive detection of Fe^(2+) and Cd^(2+) in the parts-per-billion range. This work presents a novel avenue and scientific insights on amorphous carbon-based fluorescent materials for photoelectrical devices and sensors.

Solution-processed top-contact electrodes strategy for organic crystalline field-effect transistor arrays

Organic crystals,especially ultra-thin two-dimensional(2D)ones such as monolayer molecular crystals,are fragile and vulnerable to traditional vacuum deposition.Up to now,most of the methods reported for fabricating organic field-effect transistors(OFETs)with top-electrodes on the 2D molecular crystals are based on mechanical-transfer method.Nondestructive method for large scale in-situ electrode deposition is urgent.In this work,the silver mirror reaction(SMR)is introduced to construct top-contact electrodes on 2D organic crystalline thin films.OFETs based on bilayer crystalline films with solution-processed silver electrodes show comparable performance to devices with transferred gold electrodes.In addition to that,OFETs with SMR fabricated silver electrodes show lower contact resistance than the ones with evaporated silver electrodes.Furthermore,the temperature under which SMR electrodes annealed is relatively low(60℃),making this approach applicable to varies of organic semiconductors,such as spin-coated polymer films,vacuum evaporated films,2D and even monolayer crystalline films.Besides,OFETs with sub-micrometer channel width and 25μm channel length are realized which might find practical application in the ultra-small pixel mini/micro-LEDs.

Nb_(3)Sn超导复合股线非线性力学行为研究

本文通过对Nb_(3)Sn超导复合股线在77 K和300 K下进行准静态加卸载拉伸和疲劳实验,研究了Nb_(3)Sn超导复合股线的非线性力学行为,结果表明:Nb_(3)Sn超导复合股线的准静态应力-应变曲线和能量耗散具有很强的非线性.同时,考虑塑性应变产生的损伤退化,推导了卸载过程中非线性和线性卸载模量,提出了考虑损伤的双曲面弹塑性本构模型来预测准静态加卸载应力-应变响应和能量耗散;通过疲劳损伤演化模型分析和预测Nb_(3)Sn超导复合股线在77 K和300 K下疲劳过程中的能量耗散.理论与实验结果对比表明:准静态加卸载拉伸实验中损伤退化是能量损耗产生非线性的主要原因.此外,对Nb_(3)Sn超导复合股线的疲劳断裂模式进行了分析,结果表明:Nb 3Sn芯丝组在77 K时表现为脆性断裂,在300 K时表现为韧性断裂.这些新发现为研究Nb_(3)Sn超导复合股线的非线性力学行为提供了新的视角.

Small Molecule:Polymer Blends for N-type Organic Thin Film Transistors via Bar-coating in Air

Fabricating n-type organic thin film transistors(OTFTs)based on small molecules via solution processing under atmospheric conditions remains challenging.Blending small molecules with polymer is an effective strategy to improve the solution processibility and air stability of the resulted devices.In this study,polystyrene was chosen to blend with n-type small molecule DPP1012-4F to enhance the continuity of the semiconductor layer and maintain a favorable edge-on stacking of semiconductors.The introduction of high-boiling point 1-chloronaphthalene as a solvent additive in the blending system can reduce the grain boundary defects in the microscopic morphology.These changes in aggregation behavior are confirmed by X-ray diffraction,atomic force microscopy and polarized optical microscopy analyses.Via bar-coating of the semiconductor layers in air,the electron mobility of the resulted OTFTs under the optimal condition is 0.73 cm2·V–1·s–1,which is amongst the highest n-type small molecule-based OTFTs with active layers prepared in air up to now.These results show a great potential of the blending strategy in industrial roll-to-roll manufacture of high-mobility n-type OTFTs.

Monolayer molecular crystals for low-energy consumption optical synaptic transistors

Artificial synaptic devices hold great potential in building neuromorphic computers.Due to the unique morphological features,twodimensional organic semiconductors at the monolayer limit show interesting properties when acting as the active layers for organic field-effect transistors.Here,organic synaptic transistors are prepared with 1,4-bis((5’-hexyl-2,2’-bithiophen-5-yl)ethyl)benzene(HTEB)monolayer molecular crystals.Functions similar to biological synapses,including excitatory postsynaptic current(EPSC),pair-pulse facilitation,and short/long-term memory,have been realized.The synaptic device achieves the minimum power consumption of 4.29 fJ at low drain voltage of−0.01 V.Moreover,the HTEB synaptic device exhibits excellent long-term memory with 109 s EPSC estimated retention time.Brain-like functions such as dynamic learning-forgetting process and visual noise reduction are demonstrated by nine devices.The unique morphological features of the monolayer molecular semiconductors help to reveal the device working mechanism,and the synaptic behaviors of the devices can be attributed to oxygen induced energy level.This work shows the potential of artificial neuroelectronic devices based on organic monolayer molecular crystals.

Few-layered organic single-crystalline heterojunctions for high-performance phototransistors

Photogating and electrical gating are key physical mechanisms in organic phototransistors(OPTs).However,most OPTs are based on thick and polycrystalline films,which leads to substantially low efficiency of both photogating and electrical gating and thus reduced photoresponse.Herein,high-performance OPTs based on few-layered organic single-crystalline heterojunctions are proposed and the obstacle of thick and polycrystalline films for photodetection is overcome.Because of the molecular scale thickness of the type I organic single-crystalline heterojunctions in OPTs,both photogating and electrical gating are highly efficient.By synergy of efficient photogating and electrical gating,key figures of merit of OPTs reach the highest among those based on planar heterojunctions so far as we know.The production of few-layered organic single-crystalline heterojunctions will provide a new type of advanced materials for various applications.

Fatigue behaviors and damage mechanisms for Nb_(3)Sn triple-helical structure at liquid nitrogen temperature

Nb_(3)Sn triple‐helical structure is the elementary structure in the superconducting cable of ITER magnets and undergoes prolonged fatigue loading in extreme environments leading to serious damage degradation.In this paper,the fatigue behaviors of the Nb_(3)Sn triple‐helical structure have been investigated by the strain cycling fatigue experiments at liquid nitrogen temperature.The results indicate that Nb_(3)Sn triple‐helical structures with short twist‐pitches possess excellent fatigue damage resistance than that of long twist‐pitches,such as longer fatigue life,slower damage degradation,and smaller energy dissipation.Meanwhile,a theoretical model of damage evolution has been established to reveal the effects of twist‐pitches on fatigue properties for triplehelical structures,which is also validated by the present experimental data.Furthermore,one can see that the Nb_(3)Sn superconducting wires in a triple‐helical structure with the shorter twist‐pitches have a larger elongation of helical structure and less cyclic deformation,which can be considered as the main mechanism of better fatigue damage properties for the triple‐helical structures during the strain cycling processes.These findings provide a better understanding of the fatigue properties and damage mechanisms for Nb_(3)Sn triple‐helical structures in superconducting cables of ITER magnets.

Vapor-solid interfacial reaction and polymerization for wafer-scale uniform and ultrathin two-dimensional organic films

Chemical vapor deposition is a conventional synthesis method for growing large-scale and high-quality two-dimensional materials,such as graphene,hexagonal boron nitride,and transition-metal dichalcogenides.For organic films,solution-based methods,such as inkjet printing,spin coating,and drop and micro-contact printing,are commonly used.Herein,we demonstrate a general method for growing wafer-scale continuous,uniform,and ultrathin(2-5 nm)organic films.This method is based on a copper(Cu)surfacemediated reaction and polymerization of several equivalent bromine(Br)-containingπ-conjugated small molecules(C_(12)S_(3)Br_(6),C_(24)H_(4)O_(2)Br_(2),and C_(24)H_(12)Br_(2)N_(4)),in which local surface-mediated polymerization and internalπ-πinteractions among organic molecules are responsible for the dimension and uniformity control of the thin films.Specifically,the growth rate and morphology of thin films were found to be Cu-facet-dependent,and single-crystal Cu(111)surfaces could improve the uniformity of thin films.In addition,the number of Br groups and size of organic molecules were critical for crystallinity and thin-film formation.This method can be used to fabricate heterostructures,such as organic film/graphene,giving room for various functional materials and device applications.

Tailoring crystal polymorphs of organic semiconductors towards high-performance field-effect transistors

As a quite ubiquitous phenomenon,crystal polymorph is one of the key issues in the field of organic semiconductors.This review gives a brief summary to the advances on polymorph control of thin film and single crystal of representative organic semiconductors towards high-performance field-effect transistors.Particularly,the relationship between crystal polymporh and charge transport behaviour has been discussed to shed light on the rational preparation of outstanding organic semiconducting materials with desired crystal polymorph.

Vapor-Induced Coating Method for Well-Aligned and Uniform Organic Semiconductor Single Crystals

Uniform and well-aligned organic semiconductor single crystals(OSSCs)are critical for high-performance electronic and optoelectronic device applications due to their long-range order and low defect density.However,it is still challenging to fabricate uniform and well-aligned OSSCs by an efficient and facile method.Here,we report a vapor-induced coating method to prepare uniform organic semiconductor stripe single crystals with well-aligned orientation.The coating velocity and solution concentration are important to control the stripe crystals’morphology,which influence the triple-phase contact line dewetting behavior and then change the mass transport of the meniscus.Insufficient solute supply causes the generation of dendritic crystals.Uniform stripe single crystals of high quality and pure orientation are prepared in the condition of a sufficient and suitable solute supply.Moreover,the electronic and optoelectronic properties are evaluated.Notably,the polarization-sensitive photodetectors based on the uniform stripe crystals exhibit high polarization sensitivity and its dichroic ratio of photocurrent is 1.98.This method is efficient for the preparation of various high-quality and uniform organic semiconductor stripe single crystals,opening an opportunity for high-performance organic functional devices.

Epitaxial etching of organic single crystals

Organic single crystals(OSCs)have received increasing interest in the last decades for their potential applications in flexible electronics.Although there are various subtractive manufacturing methods of organic electronics,the subtractive manufacturing of OSCs is still a challenge,since OSCs are assembled via weak van-der-Waals interactions which are vulnerable and cannot afford damages and suffer the degradation of performances after the process.Here,we develop an epitaxial etching strategy which clips the OSCs and keeps high-quality crystalline nature of the resulting materials.As a result,high-quality organic micro-ribbon arrays are fabricated which maintains 89%charge mobility in average compared with original OSCs,showing great potential of this subtractive manufacturing method in future organic electronics.

多维校正辅助激发-发射矩阵荧光法快速定量及动力学分析土壤中9-羟基芴

9-羟基芴(9-OHF)是一种常见的多环芳烃类环境有机污染物.本文提出了一种基于交替惩罚三线性分解(APTLD)和交替惩罚四线性分解(APQLD)的多维校正与三维荧光技术相结合的新策略,用于快速定量和动力学分析土壤样中9-OHF.选取因子数(F)为5和6,采用基于APTLD的三维校正方法分析拓展的三维数阵,所得土壤样中9-OHF平均回收率分别为(117.6±5.6)%和(111.1±5.1)%,半衰期分别为126.0和111.8 min,但T检验表明其预测值存在显著性差异.接着,采用基于APQLD的四维校正方法解析四维数阵.选取F=5和6,所得土壤样中9-OHF平均回收率分别为(107.8±10.6)%和(104.5±10.3)%,半衰期分别为121.6和105.0 min,T检验表明其预测结果准确可靠.此外,APQLD还给出了较好的选择性和更低的检测下限.结果表明基于APQLD的四维校正方法具有“高阶优势”,通过对四维数阵的唯一性分解,可提供准确可靠的结果,为研究复杂体系分析物的动力学过程提供了一种很有潜力的分析手段.

Nonideal double-slope effect in organic field-effect transistors

With the development of device engineering and molecular design,organic field effect transistors(OFETs)with high mobility over 10 cm2 V-1-s-1 have been reported.However,the nonideal doubleslope effect has been frequently observed in some of these OFETs,which makes it difficult to extract the intrinsic mobility OFETs accurately,impeding the further application of them.In this review,the origin of the nonideal double-slope effect has been discussed thoroughly,with affecting factors such as contact resistance,charge trapping,disorder effects and coulombic interactions considered.According to these discussions and the understanding of the mechanism behind double-slope effect,several strategies have been proposed to realize ideal OFETs,such as doping,molecular engineering,charge trapping reduction,and contact engineering.After that,some novel devices based on the nonideal double-slope behaviors have been also introduced.

Air Stable Chalcogen-Doped Rubicenes with Diradical Character

Air stable diradicaloid polycyclic aromatic hydrocarbon(PAH)materials possess unique electronic and magnetic properties for various applications.In general,long conjugated distances between two radical centers are required to improve the air stability,thereby complicating the synthetic procedures.Herein,the chalcogen containing rubicenes(O-,S-,and Se-rubicenes)were systematically investigated to understand the chalcogen effects on chalcogen-rubicene physicochemical properties.Impressively,these rubicenes presented unprecedented diradical characterwithin one simple benzene ring and excellent air stabilities.Theirdiradicalcharacterweremanifested by single-crystal X-ray studies,variable-temperature nuclear magnetic resonance,and electron spin resonance.Furthermore,the nucleus independent chemical shifts andthe anisotropy of the induced currentdensity calculations revealed that the formation of diradical was caused by a pro-aromaticity driving force.Importantly,the diradical character of rubicenes are visualizedbyFractionalOccupationNumberWeighted Electron Density(FOD)plots,which present high NFOD values from 1.651 to 1.830.This contribution provided distinctive insights into the structure and property relationship of PAH diradicals.