碳化钛介导原位还原的无标签可视化银离子检测综合实验设计

选取切合本科教学实际的科研前沿成果,将无机材料的制备和表征、光学分析方法的建立和应用融会在一起,为学生呈现了完整的课题研究流程。基于碳化钛介导的原位还原,构建了免标记、可视化的等离激元传感光学方法,实现了对样品中银离子的高灵敏、特异性检测。本实验有助于学生掌握纳米分析化学的研究范式,养成探索创新的科研思维习惯,并激发学习兴趣和科研报国热情。

Influence of nano-diamond content on the microstructure,mechanical and thermal properties of the ZK60 composites

The effect of nano diamond(ND)content on the microstructure,mechanical properties,and thermal conductivity of ZK60+x(x=0,0.05,0.1,0.15,0.2 wt.%)ND composites were investigated.The microstructures of ND/ZK60 composites were observed,which indicated that the nanoscale MgZn_(2) and ND particles distributed evenly in theα-Mg matrix.The tensile yield strength(TYS)and compressive yield strength(CYS)of the composites first increased remarkably and then decreased with further increasing the ND content.Due to the surface area of the matrix-diamond interface increased and the grains sizes of composites decreased with the amount of ND increase,which cause the coefficient of thermal expansion(CTE)of the composites reduced significantly.Meanwhile,the thermal conductivity of the composite material decreases from 129 W·m^(−1)·K^(−1) to 116 W·m^(−1)·K^(−1) with the content of ND increasing from 0.05%to 2.0%.The thermal conductivity of the composites increases to the maximum and then decrease with the increase of temperature(in temperature range of 273-573 K).The ZK60+0.05 ND showed superior mechanical and thermal conductivity property,TYS of 343.97 MPa,CYS of 341.74 MPa,elongation of 15.71%,CTE of 7.3×10^(−6)K^(−1),and thermal conductivity of 129 W·m^(−1)·K^(−1) at room temperature.It is demonstrated that the ND content has an obvious influence on the microstructure,mechanical properties,and thermal conductivity of ND/ZK60 composites.

Variable spot size optical system for a dual-wavelength laser therapy device

The majority of existing high-power laser therapeutic instruments employ a single wavelength for a single target;thus,they do not meet the requirements for clinical treatment.Therefore,this study designs an optical system for a dual-wavelength high-power laser therapeutic device with a variable spot size.The waist of the short arm of the optical cavity and the G1G2 parameter(G-parameter equivalent cavity method)is calculated using MATLAB software,the spot size and divergence angle on the lens are calculated using an ABCD matrix,and the distance between the treatment spot at different spot sizes and the transformation lens is calculated in order to design the treatment handpiece.Experiments are conducted to analyze the stability at an output power of 532 nm before beam combination and the power loss after beam combination.The results show that the output power stability of the 532-nm beam varies by less than 2%over 150 min,and the loss of both wavelengths is less than 20%,which meets the clinical requirements of the system.The safety performance can meet the requirements of national general standards for medical electrical safety.The proposed dual-wavelength laser therapy instrument has both visible wave and near-infrared wave characteristics;thus,it can accurately target both superficial vessels and vessels with a larger diameter and deeper position.This therapeutic device has the advantages of simple operation,stable and reliable laser output,high security and strong anti-interference ability,and meets the comprehensive clinical treat-ment demands of vascular diseases.

Microscopic nonlinear optical activities and ultrafast carrier dynamics in layered AgInP_(2)S_(6)

Since the emergence of graphene, transition metal dichalcogenides, and black phosphorus, two-dimensional materials have attracted significant attention and have driven the development of fundamental physics and optoelectronic devices. Metal phosphorus trichalcogenides(MPX3), due to their large bandgap of 1.3–3.5 eV, enable the extension of optoelectronic applications to visible and ultraviolet(UV) wavelengths.

Clinical characteristics and treatments of cap polyposis:a single center case series

Introduction Cap polyposis is a rare benign disease of the digestive tract,characterized by inflammatory polyps with a cap of inflammatory granulation tissue.First described in 1985 by Williams et al.[1],cap polyposis is now still introduced in case reports.The clinical course and pathogenesis of this disease are yet to be elucidated and specific therapies have not been established.

Q-switching of waveguide lasers based on graphene/WS_2 van der Waals heterostructure

We report on the operation of passively Q-switched waveguide lasers at 1 μm wavelength based on a graphene∕WS_2 heterostructure as a saturable absorber(SA). The gain medium is a crystalline Nd:YVO_4 cladding waveguide produced by femtosecond laser writing. The nanosecond waveguide laser operation at 1064 nm has been realized with the maximum average output power of 275 m W and slope efficiency of 37%. In comparison with the systems based on single WS_2 or graphene SA, the lasing Q-switched by a graphene∕WS_2 heterostructure SA possesses advantages of a higher pulse energy and enhanced slope efficiency, indicating the promisingapplications of van der Waals heterostructures for ultrafast photonic devices.

Direct observation of interlayer coherent acoustic phonon dynamics in bilayer and few-layer PtSe2

This work reports the real-time observation of the interlayer lattice vibrations in bilayer and few-layer PtSe_2 by means of the coherent phonon method. The layer-breathing mode and standing wave mode of the interlayer vibrations are found to coexist in such a kind of group-10 transition metal dichalcogenides(TMDCs). The interlayer breathing force constant standing for perpendicular coupling(per effective atom) is derived as 7.5 N/m,2.5 times larger than that of graphene. The interlayer shearing force constant is comparable to the interlayer breathing force constant, which indicates that PtSe2 has nearly isotropic interlayer coupling. The low-frequency Raman spectroscopy elucidates the polarization behavior of the layer-breathing mode that is assigned to have A1 g symmetry. The standing wave mode shows redshift with the increasing number of layers, which successfully determines the out-of-plane sound velocity of PtSe2 experimentally. Our results manifest that the coherent phonon method is a good tool to uncover the interlayer lattice vibrations, beyond the conventional Raman spectroscopy limit. The strong interlayer interaction in group-10 TMDCs reveals their promising potential in high-frequency(~terahertz) micro-mechanical resonators.

Layer-modulated two-photon absorption in MoS2:probing the shift of the excitonic dark state and band-edge

Questions hovering over the modulation of bandgap size and excitonic effect on nonlinear absorption in twodimensional transition metal dichalcogenides (TMDCs) have restricted their application in micro/nano optical modulator, optical switching, and beam shaping devices. Here, degenerate two-photon absorption (TPA) in the near-infrared region was studied experimentally in mechanically exfoliated MoS2 from single layer to multilayer. The layer-dependent TPA coefficients were significantly modulated by the detuning of the excitonic dark state (2p). The shift of the quasiparticle bandgap and the decreasing of exciton binding energy with layers were deduced, combined with the non-hydrogen model of excitons in TMDCs and the scaling rule of semiconductors. Our work clearly demonstrates the layer modulation of nonlinear absorption in TMDCs and provides support for layer-dependent nonlinear optical devices, such as optical limiters and optical switches.

Multi-gigahertz laser generation based on monolithic ridge waveguide and embedded copper nanoparticles

Copper(Cu)nanoparticles(NPs)are synthesized under the near-surface region of the Nd∶Y_(3)Al_(5)O_(12)(Nd:YAG)crystal by direct Cu^(+)ions implantation.Subsequently,the monolithic ridge waveguide with embedded Cu NPs is fabricated by C^(4+)ions irradiation and diamond saw dicing.The nonlinear optical response of the sample is investigated by the Z-scan technique,and pronounced saturable absorption is observed at the 1030 nm femtosecond laser.Based on the obvious saturable absorption of Cu NPs embedded Nd:YAG crystal,1μm monolithic mode-locked pulsed waveguide laser is implemented by evanescent field interaction between NPs and waveguide modes,reaching the pulse duration of 24.8 ps and repetition rate of 7.8 GHz.The work combines waveguides with NPs,achieving pulsed laser devices based on monolithic waveguide chips.

Two-photon absorption towards pulse modulation in mechanically exfoliated and CVD monolayer cascaded MoS2 structures

Mechanical exfoliation(ME) and chemical vapor deposition(CVD) MoS2 monolayers have been extensively studied, but the large differences of nonlinear optical performance between them have never been clarified. Here,we prepared MoS2 monolayers using ME and CVD methods and investigated the two-photon absorption(TPA)response and its saturation. We found that the TPA coefficient of the ME monolayer was about(1.88 ± 0.21)× 10^3 cm/GW, nearly two times that of the CVD one at(1.04 ± 0.15)× 10^3 cm/GW. Furthermore,we simulated and compared the TPA-induced optical pulse modulation in multilayer cascaded structures, which is instructive and meaningful for the design of optical devices such as a beam shaper and optical limiter.