Publications by authors named "Yatao Ren"

Chiral plasmonic structures have garnered increasing attention owing to their distinctive chiroptical response. Localized surface plasmon resonance can significantly enhance the circular dichroism and local electromagnetic field of chiral plasmonic structures, resulting in enhanced electromagnetic forces acting on surrounding nanoparticles. Moreover, the circular dichroism response of chiral structures provides an effective means for macroscopic adjustment of microscopic electromagnetic fields.

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Exogenous photoacoustic contrast agents such as gold nanoparticles are widely utilized in photoacoustic imaging. Enhancing the photoacoustic performance of gold nanoparticles is pivotal for improving the quality and expanding the application scope of photoacoustic imaging. In this work, the photothermal and photoacoustic responses of gold nanospheres surrounded by water excited with a pulsed laser are obtained a two-temperature model.

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To enhance the polarization distribution of electron cloud density on the catalyst surface, we have introduced a novel bimetallic-substituted dual-reaction center (DRC) catalyst (FeCo-γ-AlO) comprising iron (Fe) and cobalt (Co) for the decomplexation and mineralization of heavy metal complex Ni-EDTA in this study. Compared to the catalysts doped solely with Fe or Co, the bimetal-doped catalyst offered several advantages, including enhanced electron cloud polarization distribution, additional electron transfer pathway, and improved capacity of free radical generation. Through DFT calculations and EPR tests, we have elucidated the influences of the catalyst's adsorption toward Ni-EDTA and its decomplexation products on the electron transfer between the pollutant and the catalyst.

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Article Synopsis
  • Photoacoustic imaging using gold nanoparticles is gaining attention, particularly due to how their response to light varies with the dielectric constant, which is influenced by both wavelength and temperature.
  • This study employs the Drude-Lorentz model and Mie theory to calculate the dielectric constant and absorption efficiency of gold nanospheres, and uses finite element methods to simulate heat transfer in their surrounding environment.
  • The findings reveal that neglecting the temperature impact on the dielectric constant can result in significant inaccuracies (over 20-30%) in measuring the photothermal and photoacoustic responses, highlighting the importance of considering temperature effects for improved detection technologies and temperature measurement techniques.
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Infrared radiation (IR) characteristics are important parameters for detecting, identifying, and striking military targets in the context of systematic countermeasures. Accurate calculation of IR characteristics for aircraft is significant for the simulation of war situations and the designation of combat strategy. In this work, integrated IR characteristics of aircraft skin and exhaust plume and their interaction are investigated by considering the reflection based on a bi-directional reflectance distribution function and various influence factors such as solar irradiation, ground reflection, aerodynamic heating, and projection radiation from the background.

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As an effective tool for micro/nano-scale particle manipulation, plasmonic optical tweezers can be used to manipulate cells, DNA, and macromolecules. Related research is of great significance to the development of nanoscience. In this work, we investigated a sub-wavelength particle manipulation technique based on plasmonic optical tweezers.

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Article Synopsis
  • The study focused on creating hybrid magnetic composites of TiO loaded with CoFeO using sol-gel and hydrothermal methods, followed by extensive characterization using various spectroscopic and microscopy techniques.
  • Six organic dye pollutants and tetracycline were tested for photocatalytic degradation performance, with the CoFeO/TiO (5% /) composite showing significant efficiency, particularly under UV light.
  • The research also explored the degradation mechanism, identifying holes and super oxide radicals as key active species, while highlighting the ease of removing the composites from solutions due to their magnetic properties.
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Photothermal therapy (PTT) is a promising alternative therapy for benign or even malignant tumors. To improve the selective heating of tumor cells, target-specific photothermal conversion agents are often included, especially nanoparticles. Meanwhile, some indirect methods by manipulating the radiation and heat delivery are also adopted.

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Photoacoustic (PA) imaging using the nonlinear PA response of gold nanoparticles (GNPs) can effectively attenuate the interference from background noise caused by biomolecules (e.g., hemoglobin), thus offering a highly potential noninvasive biomedical imaging method.

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Inspired by the idea of combining conventional optical tweezers with plasmonic nanostructures, a technique named plasmonic optical tweezers (POT) has been widely explored from fundamental principles to applications. With the ability to break the diffraction barrier and enhance the localized electromagnetic field, POT techniques are especially effective for high spatial-resolution manipulation of nanoscale or even subnanoscale objects, from small bioparticles to atoms. In addition, POT can be easily integrated with other techniques such as lab-on-chip devices, which results in a very promising alternative technique for high-throughput single-bioparticle sensing or imaging.

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Article Synopsis
  • The study emphasizes the importance of controlling the thermal damage area in thermal therapy by manipulating how light moves through biological tissue.
  • It proposes a method to improve the uniformity of the specific absorption rate (SAR) in tumors, leading to reduced thermal damage in surrounding healthy tissue.
  • The research highlights that the shape, size, orientation, and incident wavelength of nanoparticles affect their scattering properties, influencing light propagation and enhancing the effectiveness of photothermal therapy.
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Article Synopsis
  • * In cases where reliable information isn't available, two important factors—the thermal accommodation coefficient (TAC) and the fractal-dependent shielding factor—must often be estimated together with PPSD.
  • * A new approach is proposed, combining TAC with the fractal shielding factor to create a "fractal-dependent TAC," which allows for the effective estimation of both PPSD and TAC from normalized LII signals, independent of most other model parameters due to low laser fluence.
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Corneal laser surgery is a widely used method for the treatment of ocular myopia, hyperopia, and astigmatism. Although it is a well-established technique, the photothermal properties of the cornea are often overlooked, causing unexpected changes in temperature during laser irradiation. Therefore, there is a need for further investigation of the temperature response of the cornea under laser irradiation.

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In this work, the coupling of magnetoplasmon polaritons (MPP) to surface phonon polaritons (SPhPs) in near-field radiative heat transfer is theoretically investigated. The system is composed of two parallel graphene-coated substrates. By applying an external magnetic field, the separated branches of MPPs can couple with SPhPs to form tunable modes.

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Black phosphorus (BP), as a two-dimensional material, has exhibited unique optoelectronic properties due to its anisotropic plasmons. In the present work, we theoretically propose a radiative thermal switch (RTS) composed of BP gratings in the context of near-field radiative heat transfer. The simply mechanical rotation between the gratings enables considerable modulation of radiative heat flux, especially when combined with the use of non-identical parameters, i.

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Nowadays, the requirement for achieving dynamic radiative cooling is more and more intense, so a cooling system is proposed and developed to meet the demand in this paper. This cooling system is composed of a filter and a periodic trapezoidal VO-Ge multilayer absorber (VGMA). The filter on the top enables the VGMA to reflect most of the solar irradiation at daytime and the absorptance or emittance of the VGMA is very different in the spectrum band of 8-13 μm for insulating and metallic VO due to the phase transition characteristic of VO.

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In this Letter, active control of near-field radiative heat transfer (NFRHT) between two isotropic materials is realized by a coating-twisting method. The two slabs are coated with graphene gratings, and then the NFRHT can be not only enhanced but also weakened, by tuning the twisted angle between the two gratings. The physical mechanism is attributed to the modes coupled by the graphene gratings and the isotropic material, which can vary with the twisted angle.

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Article Synopsis
  • This study focuses on a method for mapping optical parameters in two dimensions using the time-domain radiative transfer equation (TD-RTE).
  • The researchers utilize finite element methods along with OpenMP for parallel processing to enhance computational efficiency, and they apply sequential quadratic programming to optimize the reconstruction of absorption and scattering fields.
  • The accuracy of the results is thoroughly analyzed, taking into account measurement errors, and the findings show that their proposed reconstruction scheme is both accurate and efficient.
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In the present work, the near-field radiative heat transfer of a multilayered graphene system is investigated within the framework of the many-body theory. For the first time, the temperature distribution corresponding to the steady state of the system is investigated. Unique temperature steps are observed near both boundaries of the system, especially in the strong near-field regime.

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Thermal therapy is a very promising method for cancer treatment, which can be combined with chemotherapy, radiotherapy and other programs for enhanced cancer treatment. In order to get a better effect of thermal therapy in clinical applications, optimal internal temperature distribution of the tissue embedded with gold nanoparticles (GNPs) for enhanced thermal therapy was investigated in present research. The Monte Carlo method was applied to calculate the heat generation of the tissue embedded with GNPs irradiated by continuous laser.

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  • The study compared the photothermal conversion efficiency (PCE) of gold nanotriangles (GNTs) and gold nanorods (GNRs) using simulation and in vitro experiments on porcine muscle.
  • The discrete dipole approximation method was used to analyze the spectral characteristics and efficiency of both nanoparticles, revealing that GNTs generally have a higher PCE than GNRs for the wavelengths commonly used in photothermal therapy.
  • The experimental results indicated that while high laser power and nanoparticle concentration can lead to tissue damage like carbonization with GNRs, GNTs cause evaporation instead, making them potentially safer alternatives in therapeutic applications.
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Article Synopsis
  • Sequential quadratic programming (SQP) is utilized as an optimization method to accurately reconstruct optical parameters from time-domain radiative transfer equations (TD-RTE).
  • To enhance computational efficiency, the gradient of the objective function is computed using an adjoint equation technique.
  • The effectiveness of the technique is demonstrated through simulated results, showcasing its capability to solve the inverse problem while addressing issues related to ill-posed problems using a regularization term based on the generalized Gaussian Markov random field (GGMRF) model.
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Article Synopsis
  • * The research focused on a one-dimensional slab that absorbs and emits heat but does not scatter it, which was exposed to a pulse laser, showing that temperature changes are more influenced by thermal conductivity while radiative intensity is more affected by optical properties.
  • * Ultimately, both thermal and optical measurements are important to accurately estimate the material properties, leading to precise calculations of thermal conductivity and absorption coefficients through monitoring temperature and radiation responses at the slab's surface.
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A secondary optimization technique is proposed that allows the complex refractive index and particle size distribution (PSD) to be retrieved simultaneously by using the diffuse transmittance (T), diffuse reflectance (R), and collimated transmittance (T(c)) of a 1-D spherical particle systems as measured values. In the proposed method, two 1-D experimental samples of different thicknesses were exposed to continuous wave lasers of two different wavelengths. First, T, R, and T(c) were calculated by solving the radiative transfer equation.

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This research presents a parametric study of the time-resolved hemispherical reflectance of a semi-infinite plane-parallel slab of homogeneous, nonemitting, absorbing, and anisotropic scattering medium exposed to a collimated Gaussian pulse. The one-dimensional transient radiative transfer equation was solved by using the finite volume method. The internal reflection at the medium-air interface caused by the mismatch of the refractive indices was considered.

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