- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Up-Converting Lanthanide Fluoride Core@Shell Nanorods for Luminescent Thermometry in the First and Second Biological Windows - β-NaYF4: Yb3+, Er3+@SiO2 Temperature Sensor
摘要： Up-converting core@shell type β-NaYF4:Yb3+-Er3+@SiO2 nanorods have been obtained by a two-step synthesis process, which encompasses hydrothermal and microemulsion routes. The synthesized nanomaterial forms stable aqueous colloids and exhibits a bright dual-center emission (λex= 975 nm), i.e. up-conversion luminescence of Er3+ and down-shifting emission of Yb3+, located in the first (I-BW) and the second (II-BW) biological windows of the spectral range. The intensity ratios of the emission bands of Er3+ and Yb3+ observed in the Vis-NIR range monotonously change with temperature, i.e. the thermalized Er3+ levels (2H11/2→4I15/2/4S3/2→4I15/2) and the non-thermally coupled Yb3+/Er3+ levels (2F5/2→2F7/2/4I9/2→4I15/2 or 4F9/2→4I15/2). Hence, their thermal evolutions have been correlated with temperature using the Boltzmann type distribution and 2-th order polynomial fits for temperature sensing purposes, i.e. Er3+ 525/545 nm (max Sr = 1.31 %K-1) and Yb3+/Er3+ 1010/810 nm (1.64 %K-1) or 1010/660 nm (0.96 %K-1). Additionally, a fresh chicken breast was used as a tissue imitation in the performed ex vivo experiment, showing the advantage of the use of NIR Yb3+/Er3+ bands, vs. the typically used Er3+ 525/545 nm band ratio, i.e. better penetration of the luminescence signal through the tissue in the I-BW and II-BW. Such nanomaterials can be utilized as accurate and effective, broad-range Vis-NIR optical, contactless sensors of temperature.
关键词： Up-conversion luminescence,Luminescence intensity ratio (LIR),Functional nanomaterials,Rare earth ions,Energy transfer,Optical thermometer
更新于2025-11-25 10:30:42
-
Temperature sensitive properties of Eu2+/Eu3+ dual-emitting LaAlO3 phosphors
摘要： In this study, Eu2+/Eu3+ coexisting perovskite LaAlO3 phosphors were synthesized by a traditional high-temperature solid-phase reaction method and investigated via X-ray diffraction data, X-ray photoelectron spectroscopy and temperature-dependent photoluminescence spectra. The Eu2+/Eu3+ coexisting LaAlO3 phosphors exhibit excellent optical temperature sensing characteristics and are potential inorganic materials for temperature detection. The measured maximal absolute temperature sensitivity reaches 0.014 K-1, and the corresponding largest relative temperature sensitivity is 1.193% K-1, which are superior to most of previous reports of that. Meanwhile, the monitored signal peaks are well separated, providing a good signal discriminability. The energy level crossover relaxation of Eu2+ and Struck-Fonger crossover process involving O2–-Eu3+ charge transfer band were used to explain the different temperature-dependent responses of Eu2+ and Eu3+. This work may give new ideas for the future research of optical thermometric materials with high sensitivity and high discriminability.
关键词： Fluorescence intensity ratio,Charge transfer band,Thermometry phosphor,LaAlO3
更新于2025-11-14 15:13:28
-
A novel dynamical approach in continuous cuffless blood pressure estimation based on ECG and PPG signals
摘要： Continuous cu?ess blood pressure (BP) monitoring has attracted much interest in ?nding the ideal treatment of diseases and the prevention of premature death. This paper presents a novel dynamical method, based on pulse transit time (PTT) and photoplethysmogram intensity ratio (PIR), for the continuous cu?ess BP estimation. By taking the advantages of both the modeling and the prediction approaches, the proposed framework e?ectively estimates diastolic BP (DBP), mean BP (BP), and systolic BP (SBP). Adding past states of the cardiopulmonary system as well as present states of the cardiac system to our model caused two main improvements. First, high accuracy of the method in the beat to beat BP estimation. Second, notwithstanding noticeable BP changes, the performance of the model is preserved over time. The experimental setup includes comparative studies on a large, standard dataset. Moreover, the proposed method outperformed the most recent and cited algorithms with improved accuracy.
关键词： Cu?ess blood pressure estimation,Taken’s theorem,Multivariate adaptive regression spline,Pulse transit time,Photoplethysmogram intensity ratio
更新于2025-09-23 15:23:52
-
Single-Photon-Emission Computed Tomography with Neutron Activation for Material Inspection
摘要： A single-photon-emission computed tomography (SPECT) system with a lanthanum-bromide (LaBr3:Ce) scintillator was proposed and simulated to detect neutron-activated prompt γ-rays from suspicious materials. The optimized parameters of the SPECT system were calculated to achieve the best performance. Under the optimized conditions, energy spectra, spatial images, and elemental ratios were obtained and employed to identify hidden materials. The carbon-to-oxygen ratios of the materials calculated through the simulations were consistent with the corresponding theoretical values while the calculated nitrogen-to-oxygen ratios were slightly different from the corresponding theoretical values. In the proposed system, not only the energy spectrum of each element but also the characteristic intensity ratios obtained using the reconstructed images were used to identify the unknown elements of hidden materials in the three-dimensional spatial domain. These results demonstrate the feasibility of using the SPECT system in field applications.
关键词： Characteristic elemental intensity ratio,Neutron-activated prompt γ-rays,Single-photon-emission computed tomography
更新于2025-09-23 15:23:52
-
Electron-atom potential scattering in a corotating bicircular laser field
摘要： S-matrix theory is used in order to analyze the energy spectra of electron-atom potential scattering assisted by a bicircular (two-component circularly polarized) laser field having corotating field components. The double scattering (rescattering) is also included in the analysis by applying the second Born approximation in the expansion of the S-matrix element. We have investigated how the energy spectrum of scattered electrons is affected by the scattering angle. We have also analyzed the sensitivity of the energy spectrum to the relative phase and intensity ratio of the laser-field components. The calculated energy spectra are characterized by the plateau-like oscillatory structures with abrupt cutoffs. Positions of these cutoffs in the energy spectra are confirmed by a classical analysis. Rescattering effects can be observed in the calculated energy spectra for certain values of the scattering angle. These effects are represented by the second plateau in the energy spectrum. This is different from the process of above-threshold ionization/detachment by a bicircular laser field, where the (re)scattering effects in the photoelectron energy spectra cannot be observed in the case of corotating laser-field components.
关键词： bicircular laser field,relative phase,electron-atom scattering,rescattering effects,intensity ratio
更新于2025-09-23 15:21:01
-
Image quality assessment method based on relation intensity and details similarity
摘要： In this paper, we present an e?ective quality assessment method based on the relation intensity ratio and detail similarity for image quality assessment (IQA) with the full reference image, which ?rst allows us to compute the nonlinear gradient magnitude with Gaussian smoothing of the reference and distorted images and construct the relation intensity ratio and detail similarity between them. Next, the ?nal IQA map is formed by linearly combining the relation intensity ratio with the detail similarity. Finally, we adopt a new pooling strategy which e?ectively integrates the mean and standard deviation of the ?nal IQA map to accurately predict image quality. Experiments based on two publicly available databases show that the proposed method can provide accurate predictions compared with most state-of-the-art IQA methods.
关键词： detail similarity,relation intensity ratio,Image quality assessment
更新于2025-09-23 15:21:01
-
Optical thermometry through infrared excited green upconversion of KLa(MoO4)2:Yb3+/Er3+ Phosphor
摘要： A series of KLa(MoO4)2:Yb3+/Er3+ phosphor was synthesized by a simple hydrothermal method. Under the excitation of 980 nm laser, the phosphor show intense green bands peaked at 525 and 550 nm and a negligible 658 nm red emission (4F9/2→4I15/2), respectively. The optical temperature sensing properties of the phosphor through the fluorescence intensity ratio (FIR) method were discussed by analyzing intensities ratio of 2H11/2 and 4S3/2 emission around the range of 303–423 K. The maximum sensor sensitivity derived from the FIR of the upconversion(UC) green emissions was approximately 0.0105 K-1. This indicates that the phosphor can be used as an excellent material for optical temperature sensing.
关键词： fluorescence intensity ratio,upconversion,optical temperature sensing
更新于2025-09-23 15:21:01
-
Improvement of classification accuracy of stainless steel alloys by laser-induced breakdown spectroscopy based on elemental intensity ratio analysis
摘要： Laser-induced breakdown spectroscopy (LIBS) is a useful technique for accurate sorting of metal scraps by chemical composition analysis. In this work, a method for intensity-ratio-based LIBS classification of stainless steel applicable to highly fluctuating LIBS signal conditions is proposed. The spectral line pairs for intensity ratio calculation were selected on the consideration of elemental concentration and upper levels of emission lines. It is demonstrated that the classification accuracy can be significantly improved from that of full spectra principal component analysis or intensity-based analysis. The proposed method is considered to be suited for an industrial scrap sorting system that requires minimal maintenance and low system price.
关键词： intensity ratio,laser-induced breakdown spectroscopy (LIBS),stainless steel,classification
更新于2025-09-19 17:13:59
-
Highly sensitive optical thermometers based on unconventional thermometric coupled levels of Tm <sup>3+</sup> following a Boltzmann-type distribution in oxyfluoride glass ceramics
摘要： Oxyfluoride glass ceramics (GCs) containing b-PbF2 nanocrystals (NCs) doped with Tm3+ and Yb3+ were synthesized by a conventional melt-quenching method and a subsequent glass crystallization route. In b-PbF2:Tm3+/Yb3+ GCs, Tm3+/Yb3+ is surrounded by fluoride with a low phonon energy, ensuring its intense emissions at 362 (1D2 - 3H6), 450 (1D2 - 3F4), 478 (1G4 - 3H6), 648 (1G4 - 3F4), 700 (3F2,3 - 3H6) and 800 (3H4 - 3H6) nm excited by 976 nm laser. Furthermore, temperature-dependent upconversion luminescence (UCL) behaviors of b-PbF2:Tm3+/Yb3+ GCs were systematically investigated to explore the thermometric performance with the assistance of the fluorescence intensity ratio (FIR) method by employing conventional TCELs of 3F2,3/3H4 following a Boltzmann distribution and two unconventional coupled levels of 3F2,3/1D2 and 3F2,3/1G4 governed by a Boltzmann-type distribution. Impressively, the relative sensitivity (Sr) of 3F2,3/1D2 states (I700nm/I362nm), 3F2,3/1G4 states (I700nm/I478nm), and 3F2,3/3H4 states (I700nm/I800nm) was obtained in this work as values of 1.30% K-1, 1.38% K-1, and 0.87% K-1, respectively. Compared with the conventional TCELs of 3F2,3/3H4, the two unconventional coupled levels of 3F2,3/1D2 and 3F2,3/1G4 present preferable properties as temperature probes enabling optical ratiometric thermometers. The research in this work provides an important advance in exploring other innovative FIR methods for optical thermometers to enable an intense and precise probing signal and detect temperature accurately.
关键词： fluorescence intensity ratio,Yb3+,oxyfluoride glass ceramics,Tm3+,Boltzmann-type distribution,optical thermometers
更新于2025-09-16 10:30:52
-
Luminescent properties of Dy3+/Eu3+ doped fluorescent glass for white LED based on oxyfluoride matrix
摘要： Rare earth ion-doped fluorescent glass has become a hotspot due to its characteristics. This work shows that the prepared Dy3+ and Dy3+/Eu3+ doped glasses have white light emission under ultraviolet excitation. There is a higher yellow light/blue light (Y/B) value, indicating an increase in the covalentity of Dy-O, and decrease in the symmetry with the increasing concentration of dopants (Dy3+). The correlated color temperature (CCT) can be effectively reduced by the red light emission of Eu3+, and the order of influence of excitation wavelength on CCT is 395 nm > 382 nm > 365 nm .The delay curve demonstrates that the energy transfer from Dy3+ to Eu3+. The glass has the characteristics of anti-blue light damage and wide tunable color temperature, which illustrates that it has potential application in the field of white LED.
关键词： correlation color temperature,rare earths,oxyfluoride glass,Y/B intensity ratio,energy transfer
更新于2025-09-16 10:30:52