在多层结构的生物组织中近红外光子迁移的研究

在无损近红外光学诊断领域中 ,研究光子在多层生物组织中的迁移十分重要。本文以猪的脂肪和肌肉组成的两层结构作为研究的样品。将近红外光源和检测器置于脂肪的表面 ,由光源发出被两层组织反射的光子的一部分由检测器所接收。本文给出了光电流与光源到检测器的距离的关系以及光电流与脂肪厚度的关系。为了分析实验结果 ,用蒙特卡罗仿真来计算光子在均匀介质中迁移轨迹 ,用菲涅耳定律来决定光子包在脂肪和肌肉边界处的折射分量和反射分量。结果表明 ,仿真数据与实验符合得很好。结论是 :本文中所提供的实验和仿真方法对于分析光子在生物组织中的迁移以及优化传感器设计十分有用。

近红外光子在生物组织中迁移的仿真及应用

通过对光与生物组织相互作用物理本质的分析，介绍了一种求解光子在生物组织中迁移规律的蒙特卡罗计算方法。方法假定入射光为离散的光子，并受到生物组织的吸收和散射。认为光子在两次散射之间的长步和散射方向虽然是随机的，但可引入随机变量予以确定。对大量光子进行计算就可以获得光在生物组织中传播的宏观数据。将此方法用于脂肪组织，所得结果与实验符合甚好。说明此方法可用于检测人体皮下脂肪层的厚度。

近红外光子在三维膝关节中传输的Monte Carlo模拟

提出一种检测早期膝骨性关节炎(ROA,knee osteoarthritis)的方法。首先建立光子在膝关节组织中的传输模型,利用蒙特卡洛(MC,monte carlo)方法模拟近红外光子在三维膝关节组织中的传输;在实验中,改变膝关节模型中软骨的吸收系数和散射系数,记录光子在膝关节表面的光强分布。结果表明,溢出膝关节表面的光子包括未碰撞骨头组织直接溢出的噪音光子和撞击骨头组织后溢出的有意义光子,吸收系数和散射系数的改变会导致膝关节表面光强分布发生变化,因此可通过膝关节表面光强分布变化判断膝关节的早期病变。

Studies on rice seed quality through analysis of a large- scale T-DNA insertion population

A rice （Oryza sativa） T-DNA insertion population, which included more than 63 000 independent transgenic lines and 8 840 identified flanking sequence tags （FSTs） that were mapped onto the rice genome, was developed to systemi- cally study the rice seed quality control. Genome-wide analysis of the FST distribution showed that T-DNA insertions were positively correlated with expressed genes, but negatively with transposable elements and small RNAs. In addition, the recovered T-DNAs were preferentially located at the untranslated region of the expressed genes. More than 11 000 putative homozygous lines were obtained through multi-generations of planting and resistance screening, and measurement of seed quality of around half of them, including the contents of starch, amylose, protein and fat, with a nondestructive near-infrared spectroscopy method, identified 551 mutants with unique or multiple altered param- eters of seed quality. Analysis of the corresponding FSTs showed that genes participating in diverse functions, including metabolic processes and transcriptional regulation, were involved, indicating that seed quality is regulated by a complex network.

Lanthanide near-infrared emission and energy transfer in layered WS2/MoS2 heterostructure

Lanthanide ions have attracted great attention due to their distinct photonic properties.The optoelectronic properties and device performance are greatly affected by the interfacial coupling between the layered van der Waals heterostructure,fabricated with two or more transition metal dichalcogenide(TMD)layers.In this work,lanthanide-doped WS2/MoS2 layered heterostructures have been constructed through two synthesis steps.The doped thin films are highly textured nanosheets on wafers.Importantly,the as-prepared heterostructure exhibits efficient near-infrared emission in the range of the telecommunication window,owing to energy transfer between lanthanide ions in the two TMD layers.The use of the layered heterostructure allows the decrease of deleterious cross-relaxation due to homogeneous doping or concentration quenching.The energy transfer process was further elaborated in this work.The results suggest that lanthanide ions can effectively extend the emission band of TMD thin films and their heterostructures.The doped TMD heterostructure is highly favourable for constructing atomically thin near-infrared photonic devices.

Alkalis-doping of mixed tin-lead perovskites for efficient near-infrared light-emitting diodes

Substitution of lead(Pb)with tin(Sn)is a very important way to reduce the bandgap of metal halide perovskite for applications in solar cells,and near infrared(NIR)light-emitting diodes(LEDs),etc.However,mixed Pb/Sn perovskite becomes very disordered with high trap density when the Sn molar ratio is less than 20%.This limits the applications of mixed Pb/Sn perovskites in optoelectronic devices such as wavelength tunable NIR perovskite LEDs(Pe LEDs).In this work,we demonstrate that alkali cations doping can release the microstrain and passivate the traps in mixed Pb/Sn perovskites with Sn molar ratios of less than 20%,leading to higher carrier lifetime and photoluminescence quantum yield(PLQY).The external quantum efficiency(EQE)of Sn_(0.2)Pb_(0.8)-based NIR Pe LEDs is dramatically enhanced from 0.1%to a record value of 9.6%(emission wavelength:868 nm).This work provides a way of making high quality mixed Pb/Sn optoelectronic devices with small Sn molar ratios.

Study ofβ-cyclodextrin differential encapsulation of essential oil components by using mixture design and NIR:Encapsulation ofα-pinene,myrcene,and 3-carene as an example

The encapsulation of essential oil components in cyclodextrins(CDs)to form inclusion complexes(ICs)is an effective strategy for improving their stability and bioaccessibility.The aim of the present study was to obtain a deeper understanding of the encapsulation behavior of multi-components inβ-CD.Guest molecules ofα-pinene,myrcene,and 3-carene,having the same molecular weight,formed ICs withβ-CD by a freeze-drying method.A simplex lattice mixture design with 28 experiments was carried out.Statistical analysis was applied to analyze the encapsulation behavior of guest components,and quantitative models of guest components in ICs were constructed by coupling with near-infrared(NIR)spectroscopy and chemometrics analysis.Besides,the molecular docking technique was used to obtain the optimal conformation and explain the binding behavior of inclusion.The results suggested that the spatial structure and ratio of guest molecules were the key factors affecting the encapsulation effect.A non-destructive and rapid NIR analytical model for the guest component in ICs could be obtained by second derivative(2nd der)pretreatment.Collectively,the encapsulation of guest components inβ-CD was differentiated,and NIR could be used as a rapid and non-destructive tool for quantitative analysis of ICs.

Efficient broadband near-infrared phosphor Sr_(2)ScSbO_(6):Cr^(3+) for solar-like lighting

For healthy lighting,daily lighting that considers both visible light and near-infrared(NIR)light is necessary.However,at~900 nm,the extensively used solar-like phosphor-converted light-emitting diodes(pc-LEDs)are limited by a lack of high-performance NIR luminescent materials.We report a broadband NIR phosphor Sr_(2)ScSbO_(6):Cr^(3+) with a double perovskite-type structure,thus simultaneously demonstrating high luminescence efficiency and good thermal stability.Under 550-nm excitation,Sr_(2)ScSbO_(6):Cr^(3+) demonstrates broadband NIR emission centered at~890 nm with luminescence internal/external efficiencies of 82.0%/35.7%,respectively.Furthermore,the luminescence integrated intensity at 430 K remains at~66.4% of the initial intensity.We successfully fabricated pc-LED devices using a 465-nm-sized blue chip and other commercial phosphors,presenting a relatively complete solar-like spectrum from blue to NIR light and is expected to be used in solar-like lighting.

Lanthanide-doped near-infrared Ⅱ luminescent nanoprobes for bioapplications

Luminescent biosensing in the second nearinfrared(NIR-II) region is featured with superior spatial resolution and high penetration depth by virtue of the suppressed scattering of long-wavelength photons. Hitherto, the reported NIR-II nanoprobes are mostly based on carbon nanotubes, organic fluorophores or semiconducting quantum dots. As an alternative, trivalent lanthanide ions(Ln3+) doped nanoparticles have been emerging as a novel class of promising nanoprobes. In this review, we highlight the recent progress in the design of highly efficient Ln3+-doped NIR-II nanoparticles towards their emerging bioapplications, with an emphasis on autofluorescence-free bioimaging, sensitive bioassay, and accurate temperature sensing. Moreover, some efforts and challenges towards this rapidly expanding field are envisioned.

A near-infrared phosphorescent probe for F^- based on a cationic iridium(Ⅲ) complex with triarylboron moieties

In this work, a near-infrared (NIR) phosphorescent probe for F- based on a cationic Ir(III) complex [Ir(Bpq)2(quqo)]PF6 (1) with dimesitylboryl (Mes2B) groups on the cyclometalated CAN ligands (Bpq) and 2-(quinolin-2-yl)quinoxaline (quqo) as NAN ligand was designed and synthesized. The excited state properties of 1 were investigated in detail using molecular orbital calculations and experimental methods. Upon excitation, complex 1 shows NIR phosphorescent emission around 680 nm. Interestingly, the complex can be excited with long wavelength around 610 nm. Such long-wavelength excitation can reduce the background emission interference and improve the signal-to-noise ratio. Furthermore, the selective binding between boron atom and F- can give rise to the quenching of emission and realize the near-infrared phosphorescent sensing for F-. We wish that the results reported herein will be helpful for the further design of excellent near-infrared phosphorescent probes based on heavy-metal complexes.

Integrating lattice and gap plasmonic modes to construct dual-mode metasurfaces for enhancing light–matter interaction

Photonic structures with optical resonances beyond a single controllable mode are strongly desired for enhancing light±matter interactions and bringing about advanced photonic devices. However, the realization of effective multimodal photonic structures has been restricted by the limited tunable range of mode manipulation, the spatial dispersions of electric fields or the polarization-dependent excitations. To overcome these limitations, we create a dualmode metasurface by integrating the plasmonic surface lattice resonance and the gap plasmonic modes;this metasurface offers a widely tunable spectral range, good overlap in the spatial distribution of electric fields, and polarization independence of excitation light. To show that such dual-mode metasurfaces are versatile platforms for enhancing light±matter interactions, we experimentally demonstrate a significant enhancement of second-harmonic generation using our design, with a conversion efficiency of 1±3 orders of magnitude larger than those previously obtained in plasmonic systems. These results may inspire new designs for functional multimodal photonic structures.

Visible and near-infrared luminescence of polycatenated cationic pyridinone lanthanide networks

A series of isomorphic lanthanide coordination polymers [Ln（Ⅲ）（MBP）2（NO3）2（Br）- 2C3H60] [Ln=Eu, Tb, Er, Yb, and Gd; MBP=N,N＇-methylene-bis（pyridin-4-0ne）] featuring polycatenated sql cationic network and incorporated bromide counter ion were prepared. Their visible and near-infrared （NIR） luminescence properties were characterized by steady-state excitation and emission spectra, as well as luminescence lifetimes and quantum yields. The D2d dodecahedron coordination geometry causes visible light excitations and strongly monochromatic emissions. The external heavy-atom environment induces remarkable en- hancement on the NIR emissions. The sensitization processes are revealed by analyzing the electronic properties of MBP ligand.