周边视网膜变性广角多模影像研究进展

周边视网膜变性是眼科临床常见的病变,不同类型的变性影响不同的视网膜层次,可能对视力造成威胁。尽管现代眼底成像技术被应用于研究其病理生理机制,由于其所处的特殊部位,影像学检查困难,因此发病机制仍不清楚。本文总结了有关周边视网膜变性的多种广角成像技术的影像特征,包括超广角眼底成像、广角频域光学相干断层扫描、光学相干断层扫描血管成像、荧光素眼底血管造影等,及其发病机制或病理特点的新观点,为临床诊疗提供新的思路。由于样本量非常少,且缺乏前瞻性、长期的多模态影像的观察研究,因而目前仍无法全面评价不同类型病变的进展性及危险性。期望在更广的范围内应用多模态广角成像技术对此类疾病进行研究,指导临床干预决策。

解决一维材料黏附行为的实验方法综述

一维(1D)材料(如纳米管和纳米线)的黏附行为在集成一维组件的新型器件以及基于一维阵列的仿生黏合剂的有效制造、功能和可靠性中起着决定性作用。本文汇编并批判性地评估了最近的实验技术,旨在表征由一维材料形成的界面的粘附行为(包括当这些材料与衬底或邻近的一维材料接触时)。讨论了一维材料与表面的构象以及与之相关的多粗糙度接触的发生,并探讨了界面附着和剥离过程中黏附和摩擦的耦合。考虑了一维材料作为增强剂在纳米复合材料中的应用以及相关的界面表征技术。研究了样品制备和黏附测试过程中存在的环境条件对一维界面相互作用的潜在影响,并最终改变了一维材料的粘附行为。最后,简要介绍了当前的挑战和未来的方向,包括测试环境的系统调查和通过表面改性改变附着力。

2D Nb_(2)CT_(x) MXene/MoS_(2) heterostructure construction for nonlinear optical absorption modulation

Two-dimensional(2D)nonlinear optical mediums with high and tunable light modulation capability can significantly stimulate the development of ultrathin,compact,and integrated optoelectronics devices and photonic elements.2D carbides and nitrides of transition metals(MXenes)are a new class of 2D materials with excellent intrinsic and strong light-matter interaction characteristics.However,the current understanding of their photo-physical properties and strategies for improving optical performance is insufficient.To address this issue,we rationally designed and in situ synthesized a 2D Nb_(2)C/MoS_(2) heterostructure that outperforms pristine Nb2C in both linear and nonlinear optical performance.Excellent agreement between experimental and theoretical results demonstrated that the Nb_(2)C/MoS_(2) inherited the preponderance of Nb_(2)C and MoS_(2) in absorption at different wavelengths,resulting in the broadband enhanced optical absorption characteristics.In addition to linear optical modulation,we also achieved stronger near infrared nonlinear optical modulation,with a nonlinear absorption coefficient of Nb_(2)C/MoS_(2) being more than two times that of the pristine Nb_(2)C.These results were supported by the band alinement model which was determined by the X-ray photoelectron spectroscopy(XPS)experiment and first-principal theory calculation.The presented facile synthesis approach and robust light modulation strategy pave the way for broadband optoelectronic devices and optical modulators.

肥厚型脉络膜谱系疾病影像特征研究进展

肥厚型脉络膜谱系疾病(PSD)是近年来被定义的一组具有相似脉络膜解剖学特点及相同病理过程的一组疾病,包括中心性浆液性脉络膜视网膜病变(CSC)、息肉样脉络膜血管病变(PCV)等。其主要特征是脉络膜各血管层厚度改变和血管通透性增强。随着以光学相干断层扫描血流成像(OCTA)为代表的现代眼科影像技术不断发展,使这类疾病脉络膜各血管层的变化得以更直观地呈现,从而对该谱系疾病发病机制研究有了新的认识。本文对健康人及PSD的共同临床特点进行归纳,对各种PSD的最新影像学发现进行综述。从遗传背景及解剖学结构等不同角度,讨论各型PSD是同一疾病不同阶段的表型还是类似特征的不同疾病。以期为该类疾病的发病机制、早期临床诊断及防治提供参考。

Epitaxial quasi-2D/3D hybrid perovskite heterojunctions for photodetector with enhanced detectivity and stability

Although numerous metal halide perovskite materials have been investigated in the field of optoelectronic,the development of perovskite heterojunctions with exotic structures is still rare.Herein,we report the epitaxial growth of quasi-two-dimensional(Q-2D)perovskites on methylammonium lead iodide(MAPbI_(3))single crystals to form perovskite heterojunctions with interfacial bonding.The MAPbI_(3)adjacent to epitaxial Q-2D perovskite shows blue shifted photoluminescence with shortened lifetime,which becomes significant with the reduced layer number of the Q-2D perovskites.Our findings suggest the presence of an interfacial strain gradient leading to enhanced photocarrier separation.Accordingly,compared to the MAPbI_(3)single crystal detector,the BA_(2)MAPb_(2)I_(7)/MAPbI_(3)(BA:n-butylamine)heterojunction-based photodetector demonstrates a bandpass detecting property and exhibits 5 times enhanced external quantum efficiency and 83 times enhanced specific detectivity(D*=3.26×10^(11)Jones).Remarkably,the unencapsulated BA_(2)MAPb_(2)I_(7)/MAPbI_(3)heterojunction is stable in ambient condition for>300 days.The Q-2D/3D heterojunction shows suppressed ion inter-diffusion due to the presence of Q-2D phase.

姜黄素通过上皮-间质转化过程对口腔鳞癌细胞株HN4侵袭转移的影响

目的旨在探讨姜黄素对口腔鳞癌细胞株HN4的增殖、侵袭和凋亡效应及其分子机制。方法 0~60μmol/L姜黄素作用于口腔鳞癌细胞株HN4,24 h后应用MTT法检测细胞的生长活性;划痕实验检测细胞迁移作用;Transwell实验测定对细胞的侵袭作用;流式细胞仪检测细胞凋亡;Western blot测定P53、E-cadherin和Snail蛋白表达水平。结果 MTT检测结果显示各浓度姜黄素对癌细胞生长有抑制,其中,20μmol/L姜黄素有明显抑制。随着姜黄素浓度的增加,对细胞凋亡有明显作用。姜黄素处理后细胞周期生长阻滞于G_0/G_1期。Snail的蛋白表达量随着姜黄素的浓度增加而减少。P53和E-cadherin的表达量随着姜黄素的浓度增加而增加。结论姜黄素能显著抑制口腔鳞癌细胞株HN4的体外生长,上调P53蛋白表达诱导细胞凋亡可能是其作用机制之一。

Ant Colony Optimization Based on Adaptive Volatility Rate of Pheromone Trail

Ant colony optimization (ACO) has been proved to be one of the best performing algorithms for NP-hard problems as TSP. The volatility rate of pheromone trail is one of the main parameters in ACO algorithms. It is usually set experimentally in the literatures for the application of ACO. The present paper first proposes an adaptive strategy for the volatility rate of pheromone trail according to the quality of the solutions found by artificial ants. Second, the strategy is combined with the setting of other parameters to form a new ACO method. Then, the proposed algorithm can be proved to converge to the global optimal solution. Finally, the experimental results of computing traveling salesman problems and film-copy deliverer problems also indicate that the proposed ACO approach is more effective than other ant methods and non-ant methods.

Deformation and removal of semiconductor and laser single crystals at extremely small scales

Semiconductor and laser single crystals are usually brittle and hard,which need to be ground to have satisfactory surface integrity and dimensional precision prior to their applications.Improvement of the surface integrity of a ground crystal can shorten the time of a subsequent polishing process,thus reducing the manufacturing cost.The development of cost-effective grinding technologies for those crystals requires an in-depth understanding of their deformation and removal mechanisms.As a result,a great deal of research efforts were directed towards studying this topic in the past two or three decades.In this review,we aimed to summarize the deformation and removal characteristics of representative semiconductor and laser single crystals in accordance with the scale of mechanical loading,especially at extremely small scales.Their removal mechanisms were critically examined based on the evidence obtained from highresolution TEM analyses.The relationships between machining conditions and removal behaviors were discussed to provide a guidance for further advancing of the grinding technologies for those crystals.

Novel water-based nanolubricant with superior tribological performance in hot steel rolling

Novel water-based nanolubricants using TiO2 nanoparticles(NPs)were synthesised by adding sodium dodecyl benzene sulfonate(SDBS)and glycerol,which exhibited excellent dispersion stability and wettability.The tribological performance of the synthesised nanolubricants was investigated using an Rtec ball-on-disk tribometer,and their application in hot steel rolling was evaluated on a 2-high Hille 100 experimental rolling mill,in comparison to those without SDBS.The water-based nanolubricant containing 4 wt%TiO2 and 0.4 wt%SDBS demonstrated superior tribological performance by decreasing coefficient of friction and ball wear up to 70.5%and 84.3%,respectively,compared to those of pure water.In addition to the lubrication effect,the suspensions also had significant effect on polishing of the work roll surface.The resultant surface improvement thus enabled the decrease in rolling force up to 8.3%under a workpiece reduction of 30%at a rolling temperature of 850◦C.The lubrication mechanisms were primarily ascribed to the formation of lubricating film and ball-bearing effect of the TiO2 NPs.

Growth, characterization, and Raman spectra of the 1T phases of TiTe_(2), TiSe_(2), and TiS_(2)

High-quality large 1T phase of TiX_(2)(X = Te, Se, and S) single crystals have been grown by chemical vapor transport using iodine as a transport agent. The samples are characterized by compositional and structural analyses, and their properties are investigated by Raman spectroscopy. Several phonon modes have been observed, including the widely reported A_(1g) and E_(8) modes, the rarely reported E_(u) mode(-83 cm^(-1) for TiTe_(2), and -185 cm^(-1)for TiS_(2)), and even the unexpected K mode(-85 cm^(-1)) of TiTe_(2). Most phonons harden with the decrease of temperature, except that the K mode of TiTe_(2) and the E_(u) and “A_(2u)/Sh” modes of TiS_(2) soften with the decrease of temperature. In addition, we also found phonon changes in TiSe_(2) that may be related to charge density wave phase transition. Our results on TiX_(2) phonons will help to understand their charge density wave and superconductivity.

Interfaces between MoO x and Mo X2(X=S,Se,and Te)

In the past decades there have been many breakthroughs in low-dimensional materials,especially in two-dimensional(2D)atomically thin crystals like graphene.As structural analogues of graphene but with a sizeable band gap,monolayers of atomically thin transition metal dichalcogenides(with formula of MX2,M=Mo,W;X=S,Se,Te,etc.)have emerged as the ideal 2D prototypes for exploring fundamentals in physics such as valleytronics due to the quantum confinement effects,and for engineering a wide range of nanoelectronic,optoelectronic,and photocatalytic applications.Transition metal trioxides as promising materials with low evaporation temperature,high work function,and inertness to air have been widely used in the fabrication and modification of MX2.In this review,we reported the fabrications of one-dimensional MoS2 wrapped MoO2 single crystals with varied crystal direction via atmospheric pressure chemical vapor deposition method and of 2D MoOx covered MoX2 by means of exposing MoX2 to ultraviolet ozone.The prototype devices show good performances.The approaches are common to other transition metal dichalcogenides and transition metal oxides.

Number Sequencing and Architecture

In Chinese, Mathematics is “数学”, i.e. Numbers （数） Knowledge （学）. Human identifies us ourselves from the whole one of the Universe by means of numbers, and numbers are equal object status identities, and numbers counting means repetition, i.e. the process or time dimension. Given a series of n numbers, a1 , a2 , … , an , n∈N, i.e. the n objects of status, and a general formula a（i） for ordering all of the number terms by i （i=1 to n） can be generated, which shows a process of counting, and from sequencing to progression, some properties are extracted.

Growth mechanisms of interfacial carbides in solid-state reaction between single-crystal diamond and chromium

Interfacial bonding is one of the most challenging issues in the fabrication,and hence comprehensively influences the properties of diamond-based metal matrix composites(MMCs)materials.In this work,solid-state(S/S)interface reaction between single-crystal synthetic diamond and chromium(Cr)metal was critically examined with special attention given to unveil the role of crystal orientation in the for-mation and growth of interfacial products.It has been revealed that catalytically converted carbon(CCC)was formed prior to chromium carbides,which is counterintuitive to previous studies.Cr 7 C 3 was the first carbide formed in the S/S interface reaction,aided by the relaxation of diamond lattices that re-duces the interfacial mismatch.Interfacial Cr 7 C 3 and Cr 3 C 2 carbides were formed at 600 and 800℃,respectively,with the growth preferred on diamond(100)plane,because of its higher density of surface defects than(111)plane.Interfacial strain distribution was quasi-quantitively measured using windowed Fourier Transform-Geometric Phase Analysis(WFT-GPA)analysis and an ameliorated strain concentration was found after the ripening of interfacial carbides.Textured morphologies of Cr_(3)C_(2) grown on diamond(100)and(111)planes were perceived after S/S interface reaction at 1000℃,which is reported for the first time.The underlying mechanisms of Cr-induced phase transformation on diamond surface,as well as the crystal orientation dependent growth of interfacial carbides were unveiled using the first-principles calculation.The formation and growth mechanisms of Cr_(3)C_(2) were elucidated using SEM,TEM and XRD analyses.Finally,an approach for tailoring the interfacial microstructure between synthetic diamond and bonding metals was proposed.

Search-Based Software Test Data Generation for Path Coverage Based on a Feedback-Directed Mechanism

Automatically generating test cases by evolutionary algorithms to satisfy the path coverage criterion has attracted much research attention in software testing.In the context of generating test cases to cover many target paths,the efficiency of existing methods needs to be further improved when infeasible or difficult paths exist in the program under test.This is because a significant amount of the search budget(i.e.,time allocated for the search to run)is consumed when computing fitness evaluations of individuals on infeasible or difficult paths.In this work,we present a feedback-directed mechanism that temporarily removes groups of paths from the target paths when no improvement is observed for these paths in subsequent generations.To fulfill this task,our strategy first organizes paths into groups.Then,in each generation,the objective scores of each individual for all paths in each group are summed up.For each group,the lowest value of the summed up objective scores among all individuals is assigned as the best aggregated score for a group.A group is removed when no improvement is observed in its best aggregated score over the last two generations.The experimental results show that the proposed approach can significantly improve path coverage rates for programs under test with infeasible or difficult paths in case of a limited search budget.In particular,the feedback-directed mechanism reduces wasting the search budget on infeasible paths or on difficult target paths that require many fitness evaluations before getting an improvement.

Organic polaritonic light-emitting diodes with high luminance and color purity toward laser displays

Achieving high-luminescence organic light-emitting devices(OLEDs)with narrowband emission and high color purity is important in various optoelectronic fields.Laser displays exhibit outstanding advantages in next-generation display technologies owing to their ultimate visual experience,but this remains a great challenge.Here,we develop a novel OLED based organic single crystals.By strongly coupling the organic exciton state to an optical microcavity,we obtain polariton electroluminescent(EL)emission from the polariton OLEDs(OPLEDs)with high luminance,narrow-band emission,high color purity,high polarization as well as excellent optically pumped polariton laser.Further,we evaluate the potential for electrically pumped polariton laser through theoretical analysis and provide possible solutions.This work provides a powerful strategy with a material–device combination that paves the way for electrically driven organic single-crystal-based polariton luminescent devices and possibly lasers.

Enormous enhancement in electrical performance of few-layered MoTe2 due to Schottky barrier reduction induced by ultraviolet ozone treatment

Doping can improve the band alignment at the metal-semiconductor interface to modify the corresponding Schottky barrier,which is crucial for the realization of high-performance logic components.Here,we systematically investigated a convenient and effective method,ultraviolet ozone treatment,for p-type doping of MoTe2 field-effect transistors to enormously enhance the corresponding electrical performance.The resulted hole concentration and mobility are near 100 times enhanced to be〜1.0×10^13 cm^-2 and 101.4 cm^2/(V·s),respectively,and the conductivity is improved by 5 orders of magnitude.These values are comparable to the highest ones ever obtained via annealing doping or non-lithographic fabrication methods at room temperature.Compared with the pristine one,the photoresponsivity(522 mA/W)is enhanced approximately 100 times.Such excellent performances can be attributed to the sharply reduced Schottky barrier because of the surface charge transfer from MoTe2 to MoOx(x<3),as proved by photoemission spectroscopy.Additionally,the p-doped devices exhibit excellent stability in ambient air.Our findings show significant potential in future nanoelectronic and optoelectronic applications.

Deformation, failure and removal mechanisms of thin film structures in abrasive machining

Thin film structures are becoming increasingly more important for industrial applications such as the making of solar panels, microelectronic devices and micro systems. However, the challenges encountered in the machining of thin film structures have been a bottleneck that impedes further wide spread uses of such structures. The development of material removal processes that are capable of producing a damage free surface at high removal rates is critical for cost effective production. Such development relies highly on a comprehensive understanding of the deformation, failure and removal mechanisms of thin film structures involved in mechanical loading. In this paper, the current understanding of the deformation characteristics of thin film systems was reviewed to provide important insights into the interracial failure under mechanical loading, with focuses on the interfacial failure mechanisms and existing problems in the machining of thin film structures. The key characterization techniques were outlined. In particular, the recent progress in the abrasive machining of a thin film multilayer structure was summarized. The potential research directions were also presented in the end of the review.

Catalyst-free synthesis and mechanical characterization of TaC nanowires

TaC nanowires are expected to be an ideal reinforcing material in ultra-high-temperature ceramics. However, their growth mechanisms and mechanical properties remain unclear, and low-cost large-scale synthesis has not been realised. In this study,bulk synthesis of [100]-oriented TaC nanowires is accomplished by carbothermal synthesis through a direct vapor-solid mechanism. Thermal resonance test results show that the synthesized square TaC nanowires with cross-sectional side-lengths of 65 to 497 nm have a size-independent Young’s modulus of(510.6±12.6) GPa;very close to the corresponding values of their bulk counterparts, but differing considerably from previously published measurements. Molecular dynamics(MD) simulations show that TaC nanowires with side-lengths of above 15 nm have a constant Young’s modulus of 517 GPa, and size effects on the modulus values should only occur at side-lengths below 15 nm. During bending tests, the TaC nanowires fracture into several segments in a brittle mode, and exhibit an increasing fracture strain from 1.88% to 4.28% as their side-length decreases from 489 to 90 nm. Weibull statistics analyses and TEM observations indicate that the failure of the nanowires should be primarily dependent on the number and size of surface defects. MD simulations further reveal that the defect-free TaC nanowires fail brittlely at a theoretical strain up to 5.76%.

Individualized red-cell transfusion strategy for non-cardiac surgery in adults:a randomized controlled trial

Background:Red-cell transfusion is critical for surgery during the peri-operative period;however,the transfusion threshold remains controversial mainly owing to the diversity among patients.The patient’s medical status should be evaluated before making a transfusion decision.Herein,we developed an individualized transfusion strategy using the West-China-Liu’s Score based on the physiology of oxygen delivery/consumption balance and designed an open-label,multicenter,randomized clinical trial to verify whether it reduced red cell requirement as compared with that associated with restrictive and liberal strategies safely and effectively,providing valid evidence for peri-operative transfusion.Methods:Patients aged>14 years undergoing elective non-cardiac surgery with estimated blood loss>1000 mL or 20%blood volume and hemoglobin concentration<10 g/dL were randomly assigned to an individualized strategy,a restrictive strategy following China’s guideline or a liberal strategy with a transfusion threshold of hemoglobin concentration<9.5 g/dL.We evaluated two primary outcomes:the proportion of patients who received red blood cells(superiority test)and a composite of in-hospital complications and all-cause mortality by day 30(non-inferiority test).Results:We enrolled 1182 patients:379,419,and 384 received individualized,restrictive,and liberal strategies,respectively.Approximately 30.6%(116/379)of patients in the individualized strategy received a red-cell transfusion,less than 62.5%(262/419)in the restrictive strategy(absolute risk difference,31.92%;97.5%confidence interval[CI]:24.42-39.42%;odds ratio,3.78%;97.5%CI:2.70-5.30%;P<0.001),and 89.8%(345/384)in the liberal strategy(absolute risk difference,59.24%;97.5%CI:52.91-65.57%;odds ratio,20.06;97.5%CI:12.74-31.57;P<0.001).No statistically significant differences were found in the composite of in-hospital complications and mortality by day 30 among the three strategies.Conclusion:The individualized red-cell transfusion strategy using the West-China-Liu’s Score reduced red-cell transfusion without increasing in-hospital complications and mortality by day 30 when compared with restrictive and liberal strategies in elective non-cardiac surgeries.Trial registration:ClinicalTrials.gov,NCT01597232.

Giant quartic-phonon decay in PVD-grownα-MoO_(3) flakes

Elementary excitations,such as in-plane anisotropic phonons and phonon polaritons(PhPs),inα-MoO_(3) play key roles in its outstanding physical properties like high carrier mobility and ultralow phonon thermal conductivity().Understanding the excitation mechanisms like phonon–phonon interactions is the most fundamental step to further applications.Here,we report on the systematic Raman investigations on phonon anisotropy and anharmonicity of representative Mo–O stretching vibration phonon modes(SVPMs)in physical vapor deposition(PVD)-grownα-MoO_(3) flakes.Polarizations of SVPMs verify the phonon anisotropy.The abnormal temperature dependence of SVPMs reveals that giant quartic-phonon decay dominates the phonon anharmonicity inα-MoO_(3).An ultrashort phonon lifetime of~0.34 ps gives evidence of theoretically predicted ultralow inα-MoO_(3).Our findings give deep insight into the phonon–phonon interactions inα-MoO_(3) and provide an indicator for its extreme thermal device applications.