Recent developments of fluorescence imaging technology in the second near-infrared window

Background:Fluorescence bio-imaging in the second near-infrared window(NIR-II FL,1000-1700nm)has great potential in clinical theranostics,which is of great importance providing precise locations of lesions and molecular dynamic actions simultaneously in a single nanoprobe.Methods:T here has been an upsurge of multidisciplinary research focusing on developing functional types of inorganic and organic nanoprobes that can be used for NIR-II FL with the high spatiotemporal resolution,deep tissue penetration,and negligible auto-fluorescence.Results:In this mini-review,we summarize recent progress in inorganic/organic NIR-II FL nanoprobes.We introduce the design and properties of inorganic and organic nanoprobes,in the order of single-walled carbon nanotubes,quantum dots,rare-earth-doped nanoparticles,metal nanoclusters and organic fluorophores,expect to realize precise diagnosis and efficient image-guided therapy.Conclusion:Meanwhile,to elucidate the problems and perspectives,we aim to offer diverse biological applications of inorganic/organic NIR-II FL nanoprobes and accelerate the clinical transformation progress.

Three-dimensional channel flow of second grade fluid in rotating frame

An analysis is performed for the hydromagnetic second grade fluid flow between two horizontal plates in a rotating system in the presence of a magnetic field. The lower sheet is considered to be a stretching sheet, and the upper sheet is a porous solid plate. By suitable transformations, the equations of conservation of mass and momentum are reduced to a system of coupled non-linear ordinary differential equations. A series of solutions to this coupled non-linear system are obtained by a powerful analytic technique, i.e., the homotopy analysis method （HAM）. The results are presented with graphs. The effects of non-dimensional parameters R, A, M2, a, and K2 on the velocity field are discussed in detail.

Robust Blind Separation for MIMO Systems against Channel Mismatch Using Second-Order Cone Programming

To improve the deteriorated capacity gain and source recovery performance due to channel mismatch problem,this paper reports a research about blind separation method against channel mismatch in multiple-input multiple-output(MIMO) systems.The channel mismatch problem can be described as a channel with bounded fluctuant errors due to channel distortion or channel estimation errors.The problem of blind signal separation/extraction with channel mismatch is formulated as a cost function of blind source separation(BSS) subject to the second-order cone constraint,which can be called as second-order cone programing optimization problem.Then the resulting cost function is solved by approximate negentropy maximization using quasi-Newton iterative methods for blind separation/extraction source signals.Theoretical analysis demonstrates that the proposed algorithm has low computational complexity and improved performance advantages.Simulation results verify that the capacity gain and bit error rate(BER) performance of the proposed blind separation method is superior to those of the existing methods in MIMO systems with channel mismatch problem.

基于深度学习的快速长时视觉跟踪算法

在目标尺寸变化、遮挡和出视场等复杂长时视觉跟踪环境下,现有基于深度学习的视觉跟踪算法很难对目标进行实时准确的跟踪。针对该问题,提出一种快速的长时视觉跟踪算法,该算法由一个快速短时视觉跟踪算法和一个快速全局重检测模块组成。在基准算法SiamRPN中加入二阶通道与区域空间融合的注意力模块作为短时视觉跟踪算法,在保证快速性的同时,提高算法的短时视觉跟踪精确度和成功率;为使改进后的短时视觉跟踪算法具有快速的长时视觉跟踪能力,在算法中加入提出的基于模板匹配的全局重检测模块,该模块使用轻量级网络和快速的相似度判断方法,加快重检测速率。在OTB100、LaSOT、UAV20L、VOT2018-LT、VOT2020-LT等5个数据集上进行测试,实验结果表明,所提算法在长时视觉跟踪中具有优越的跟踪性能,平均速度达104帧/s。

可见-近红外二区双通道荧光成像系统

本文基于光学手段,开发出了一套能够兼顾可见光与近红外二区(NIR-Ⅱ)窗口的双通道宏观成像系统,能够实时输出具有NIR-Ⅱ荧光信息的高质量明场图像,解决了常规的NIR-Ⅱ宏观成像系统提供的荧光图像与明场图像割裂较大的问题。实验中利用不同厚度的脂肪组织测试了吲哚菁绿的NIR-Ⅱ窗口荧光信号分别在1 100~1 700 nm长通滤光片与1 300~1 700 nm长通滤光片下的抗散射能力与成像表现。接着利用所搭建的双通道宏观成像系统分别在小鼠以及大鼠模型上实现了淋巴结成像并模拟进行了淋巴结的切除手术,模拟了对腹腔淋巴结清扫的过程。最后,在大鼠模型上添加了不同厚度的生物脂肪组织,模拟实际手术中脂肪组织覆盖在淋巴结上的情况,观察双通道系统的穿透能力。可见近红外二区双通道荧光成像系统通过给操作者提供直观的影像信息,缩减手术时间、提高患者的预后,在临床手术导航中具有较大的应用潜力。

京杭运河二通道待闸锚地容量探讨

以京杭运河二通道上设置的八堡船闸待闸锚地为研究对象,基于运量预测、通航条件分析、八堡船闸运行特点等前期成果,通过经验公式计算、排队模型对待闸锚地所需锚泊位数量分析计算,同时利用三堡船闸待闸锚地布置情况进行实例对比分析,并提出针对性的锚地改造措施。结果表明,合适的待闸锚地容量为不小于3个闸次船舶数量,并建议设置远程调度锚地进行梯级调度。

Blind Equalization Based on RLS Algorithm Using Adaptive Forgetting Factor for Underwater Acoustic Channel

Blind equalization based on adaptive forgetting factor, recursive least squares （RLS） with constant modulus algorithm （CMA）, is investigated. The cost function of CMA is simplified to meet the second norm form to ensure the stability of RLS-CMA, and thus an improved RLS-CMA （RLS-SCMA） is established. To further improve its performance, a new adaptive forgetting factor RLS-SCMA （ARLS-SCMA） is proposed. In ARLS-SCMA, the forgetting factor varies with the output error of the blind equalizer during the iterative process, which leads to a faster convergence rate and a smaller steady-state error. The simulation results prove the effectiveness under the condition of the underwater acoustic channel.

The Tight Bound for the Number of Pilots in Channel Estimation for OFDM Systems

Coherent detection in OFDM systems requires accurate channel state information (CSI) at the receiver. Channel estimation based on pilot-symbol-assisted transmissions provides a reliable way to obtain CSI. Use of pilot symbols for channel estimation, introduces overhead and it is desirable to keep the number of pilot symbols as minimum as possible. This paper introduces a new tight bound for the number of pilots in channel estimation using adaptive scheme in OFDM systems. We calculate the minimum number of necessary pilots using two approaches. The first approach for the number of pilots is obtained based on Doppler frequency shift estimation and the second approach is acquired based on channel length estimation using second order statistics of received signal. Finally we obtain the tight bound for the number of pilots using attained values.

SECOND-MOMENT CLOSURE FOR MODELLING THE NEAR-WALL TURBULENCE IN 3D MEAN FLOWS

A second-moment closure for the near-wall turbulence is proposed. The limiting behaviour of this closure near a wall is consistent with that of the exact Reynolds-stress transport equations, and it converts asymptotically into a high- Reynolds-number closure remote from the wall. The closure is applied to a pressure- driven 3D transient channel flow. The predicted results are in fair agreement with the DNS data.

Biological imaging without autofluorescence in the second near-infrared region

Fluorescence imaging is capable of acquiring anatomical and functional infor- mation with high spatial and temporal resolution. This imaging technique has been indispensable in biological research and disease detection/diagnosis. Imaging in the visible and to a lesser degree, in the near-infrared （NIR） regions below 900 nm, suffers from autofluorescence arising from endogenous fluorescent molecules in biological tissues. This autofluorescence interferes with fluorescent molecules of interest, causing a high background and low detection sensitivity. Here, we report that fluorescence imaging in the 1,500-1,700-nm region （termed ＂NIR-IIb＂） under 808-nm excitation results in nearly zero tissue autofluorescence, allowing for background-free imaging of fluorescent species in otherwise notoriously autofluorescent biological tissues, including liver. Imaging of the intrinsic fluorescence of individual fluorophores, such as a single carbon nanotube, can be readily achieved with high sensitivity and without autofluorescence background in mouse liver within the 1,500-1,700-nm wavelength region.

pH-sensitive and biodegradable charge-transfer nanocomplex for second near-infrared photoacoustic tumor imaging

The emerging technique of photoacoustic imaging,especially in the near infra-red(NIR)window,permits high resolution,deep-penetration,clinically reliable sensing.However,few contrast agents are available that can specifically respond to intricate biological environments,and which are biodegradable and biocompatible.Herein,we in troduce a new class of pH-sensitive orga nic photoacoustic con trast age nt that operates in the second NIR window(NIR-II,960-1,700 nm),which is derived from the self-assembled charge-transfer nanocomplex(CTN)by 3,3',5,5'-tetramethylbenzidine(TMB)and its dication structure(TMB++).The unique NIR-ll-responsive CTN can specifically respond to pH change in the physiological range and allows noninvasive and sensitive visualization of the tumor acidic microenvironment(e.g.at pH5)in mice with higher signal-to-noise ratio.The CTN is biodegradable under physiological conditions(e.g.pH 7.4),which alleviates the biosafety concern of nan oparticle accumulati on in vivo.These results clearly show the pote ntial of the TMB/TMB++-based CTN as a promisi ng pH-activated and biodegradable molecular probe for specific tumor photoacoustic imaging in the NIR-II region.

Two-dimensional near-infrared photonic crystal fabrication by generation of void channels in solid resin

Two-dimensional (2D) triangular void channel photonic crystals with different lattice constants stacked in two different directions were fabricated by using femtosecond laser micro-explosion in solid polymer material. Fundamental and higher-order stop gaps were observed both in the infrared transmission and reflection spectra. There is an approximately linear relationship between the gap position and the lattice constant. The suppression of the fundamental gap is as high as 70% for 24-layer structures stacked in the T-M direction.

基于三维激光扫描的泗阳二站肘形进水流道的测量与分析

三维激光扫描技术以其精度高、测速快等特点在水利行业发挥巨大作用。为了明确泗阳二站改造施工完成后流道的实际曲面形状、尺寸与设计值的偏差情况,基于三维激光扫描技术,对泗阳二站改造施工后进水流道的形状尺寸进行检测,并对横断面尺寸与设计尺寸进行对比分析。结果表明,泗阳二站混凝土流道改造工程的施工尺寸偏差控制总体较好,满足设计要求。其中,施工区域范围内流道内壁表面的平整度偏差总体在±1.4 mm范围内;改造程度较小的控制断面施工完成后的尺寸偏差总体在±10 mm以内;改造程度较大的控制断面施工完成后的尺寸偏差值均在±20mm范围内。现场测量结果可为泗阳二站的流道施工质量评定提供参考依据,同时也可为泵站流道的施工精度提供评判依据。

Rational Design and Application of an Indolium-Derived Heptamethine Cyanine with Record-Long Second Near-Infrared Emission

Heptamethine cyanine dyes,typified by indocyanine green,have been extensively employed as bioimaging indicators and theranostic agents.Significant efforts have been made to develop functional heptamethine cyanine dyes with outstanding bioimaging and theranostic utilities.In this work,we rationally designed and successfully developed a novel indolium-like heptamethine cyanine dye by installing indolium-derived polycyclic aromatic hydrocarbons on the terminal ends of a conjugated polyene backbone.This dye showed excellent photostability and showed bright fluorescent emission in the second near-infrared(NIR-Ⅱ)window with a peak at approximately 1120 nm.Such long wavelength emission prompted a superior bioimaging resolution in vivo.In particular,this NIR-Ⅱ dye had the remarkable capability of marking the blood vessels of the hindlimbs,abdomens,and brains of mice.More significantly,this dye involved a typical indolium-like heptamethine skeleton and exhibited two strong absorption bands in the 700–1300 nm NIR range,which endowed it with an intrinsic tumor-targeting capability and a high photothermal conversion efficiency(up to 68.2%),serving for the photothermal therapy of tumors under the guidance of NIR-Ⅱ fluorescence imaging.This work provides an efficient design strategy for achieving indolium-like heptamethine cyanine dyes with further NIR-Ⅱ emission.

基于WOA18的西北太平洋第一、二岛链间声速特征分析

本文基于WOA18温盐剖面数据集,利用声速经验公式计算了西北太平洋第一、二岛链间海区的声速剖面,研究了声速特征信息的诊断方法。通过提取声跃层、声道轴等声速特征信息,分别对表面声速、声跃层、声道轴进行分析,统计表面声速、声跃层和声道轴在各个季节的分布情况,得到了研究海区不同声学要素的季节变化特征。结果表明,表面声速主要在1520~1540 m/s区间变化,等值线基本与纬线平行,呈现出自低纬向高纬递减的趋势,声速值随季节变化较大;声跃层平均位置在低纬海区和高纬海区的差异较大,大约在100~650 m区域,低纬海区的声跃层受季节变化影响小,高纬海区的声跃层受季节变化影响大;声道轴深度基本在800 m以深区域,总体上呈现南北深、中间浅的分布态势且四季变化幅度较小。

Fusing Thienoisoindigo to the Conjugated Ribbons with Strong Absorption in the Second Near-Infrared Window

Organic dyes with strong absorption in the second near-infrared(NIR-II)window(1000-1700 nm)have multiple applications.However,the design and synthesis of stable NIR-II absorbing organic dyes are very challenging and constantly defy our synthetic ability.In this work,we have successfully synthesized a series of soluble and stable fused thienoisoindigo(nThIID)ribbons.The absorption maximum(λ_(max))of the ribbons increases from 644 nm of 1ThIID to 1252 nm of 6ThIID.Importantly,nThIIDs with n≥4 all display strong absorption in the NIR-II window with molar extinction coefficients(ε_(max))greater than 105 L mol^(−1)cm^(−1)atλmax.These molecules are promising photothermal conversion dyes with photothermal conversion efficiencies of ca.60%under 1064 nm laser irradiation.

我国油气矿业权市场化管理改革的思考

2010年以来,党中央和国务院持续推进油气体制改革工作,并连续发布了生态文明体制改革方案、矿业权出让制度改革方案、矿产资源权益金制度改革方案和油气体制改革等多部重要改革文件,为落实党中央和国务院的决策部署,自然资源主管部门进行了十多年的油气矿业权市场化管理改革实践和探索,取得了初步成效。为进一步深化改革,激发市场活力,促进油气资源增储上产和提升油气资源保障能力,本文在系统梳理油气矿业权市场化改革探索历程的基础上,总结归纳了油气探矿权出让管理市场化改革取得的初步成效,分析矿业权市场化改革的深化在油气市场投资主体多元化、风险投资和市场融资、投资主体的投资回报预期、勘探开发关键技术、油服市场以及油气探矿权出让管理改革五方面面临的新形势与新挑战,提出应从6个方面深化改革:1)实施鼓励政策吸引更多市场主体参与油气上游市场;2)拓展市场融资渠道分担油气行业的高投入、高风险;3)建立和培育油气探矿权交易二级市场;4)培育完善油服市场,更好地为投资主体支撑;5)继续完善油气探矿权出让制度;6)统一大市场的健康有效发展需要政府的积极有为和企业的积极参与。

Integrating the second near-infrared fluorescence imaging with clinical techniques for multimodal cancer imaging by neodymiumdoped gadolinium tungstate nanoparticles

Second near-infrared(NIR-II)fluorescence imaging is a recently emerged technique and is highly useful for accurate diagnosis of cancer.Although a diverse array of fluorescent nanomaterials have been developed to enable NIR-II fluorescence in various situations,they normally fail to unify the clinical techniques,such as computed tomography(CT)and magnetic resonance imaging(MRI).Therefore,exploiting multimodal agents to integrate the newly emerged NIR-II fluorescence and traditional clinical techniques would be of key significance.Here,we report a rational fabrication of neodymium(Nd)-doped gadolinium tungstate nanoparticles(NPs)that are subsequentially decorated with a hydrophilic layer and demonstrate that they can achieve the harmonious integration of NIR-II fluorescence imaging,CT,and MRI.The NIR-II fluorescence emission was activated by an incident light with discrete wavelength ranging from 250 to 810 nm.NIR-II fluorescence-CT-MRI associated trimodal imaging was subsequently demonstrated for breast cancer by an 808 nm laser,along with the estimation of NIR-II fluorescence imaging for cervical cancer.The integration of newly emerged and traditional clinical imaging techniques highlights the huge potential of rare-earth-doped NPs for multimodal imaging of different types of cancer.

Second Near-Infrared Photothermal Therapy with Superior Penetrability through Skin Tissues

Photothermal therapy(PTT)triggered by second near-infrared(NIR-II)light(1000–1400 nm)has shown great potential in tumor ablation because of its good tissue penetrability.However,NIR-II PTT still cannot treat tumors underneath skin because of the light scattering effect of skin components.This research aims to promote the NIR-II penetrability of skin tissue by weakening the light scattering effect from the refractive index inhomogeneity among skin constituents.

Second near-infrared window persistent luminescence nanomaterials for in vivo bioimaging

Optical imaging in the second near-infrared(NIR-II,1,000-1,700 nm)window with much reduced tissue scattering plays a crucial role in life sciences due to its high sensitivity and high spatio-temporal resolutions^([1]).Therefore,researchers are committed to developing various types of NIR-II fluorescent probes,such as organic dyes.