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- 2019
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- infrared image
- target detection
- lucas–kanade method (LK)
- local contrast method (LCM)
- facet model
- target detection
- zero-crossing point
- Image processing
- Infrared camera
- Eye movement
- Optoelectronic Information Science and Engineering
- Chinese Academy of Sciences
- Gunma University
- University of Chinese Academy of Science
- Xi’an Institute of Optics and Precision Mechanics Chinese Academy of Science
- University of Science and Technology of China
- Space Star Technology Co. LTD
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Carbon stars in the X-shooter Spectral Library
摘要： In a previous paper, we assembled a collection of medium-resolution spectra of 35 carbon stars, covering optical and near-infrared wavelengths from 400 to 2400 nm. The sample includes stars from the Milky Way and the Magellanic Clouds, with a variety of (J ? Ks) colors and pulsation properties. In the present paper, we compare these observations to a new set of high-resolution synthetic spectra, based on hydrostatic model atmospheres. We ?nd that the broad-band colors and the molecular-band strengths measured by spectrophotometric indices match those of the models when (J ? Ks) is bluer than about 1.6, while the redder stars require either additional reddening or dust emission or both. Using a grid of models to ?t the full observed spectra, we estimate the most likely atmospheric parameters Te?, log(g), [Fe/H] and C/O. These parameters derived independently in the optical and near-infrared are generally consistent when (J ? Ks) < 1.6. The temperatures found based on either wavelength range are typically within ±100 K of each other, and log(g) and [Fe/H] are consistent with the values expected for this sample. The reddest stars ((J ? Ks) > 1.6) are divided into two families, characterized by the presence or absence of an absorption feature at 1.53 μm, generally associated with HCN and C2H2. Stars from the ?rst family begin to be more a?ected by circumstellar extinction. The parameters found using optical or near-infrared wavelengths are still compatible with each other, but the error bars become larger. In stars showing the 1.53 μm feature, which are all large-amplitude variables, the e?ects of pulsation are strong and the spectra are poorly matched with hydrostatic models. For these, atmospheric parameters could not be derived reliably, and dynamical models are needed for proper interpretation.
关键词： stars: carbon,stars: atmospheres,infrared: stars
更新于2025-09-04 15:30:14
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Infrared limb emission measurements of aerosol in the troposphere and stratosphere
摘要： Altitude-resolved aerosol detection in the upper troposphere and lower stratosphere (UTLS) is a challenging task for remote sensing instruments. Infrared limb emission measurements provide vertically resolved global measurements at day- and nighttime in the UTLS. For high-spectral-resolution infrared limb instruments we present here a new method to detect aerosol and separate between ice and non-ice particles. The method is based on an improved aerosol–cloud index that identifies infrared limb emission spectra affected by non-ice aerosol or ice clouds. For the discrimination between non-ice aerosol and ice clouds we employed brightness temperature difference correlations. The discrimination thresholds for this method were derived from radiative transfer simulations (including scattering) and Michelson Interferometer for Passive Atmospheric Sounding (MIPAS)/Envisat measurements obtained in 2011. We demonstrate the value of this approach for observations of volcanic ash and sulfate aerosol originating from the Grímsv?tn (Iceland, 64? N), Puyehue–Cordón Caulle (Chile, 40? S), and Nabro (Eritrea, 13? N) eruptions in May and June 2011 by comparing the MIPAS volcanic aerosol detections with Atmospheric Infrared Sounder (AIRS) volcanic ash and SO2 measurements.
关键词： aerosol detection,infrared limb emission,volcanic ash,sulfate aerosol,ice clouds,UTLS
更新于2025-09-04 15:30:14
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Spectral interval optimization on rapid determination of prohibited addition in pesticide by ATR‐FTIR
摘要： BACKGROUND: Acetamiprid, as a low toxicity pesticide, had already been extensively used to increase plant production and quality. Although fipronil had been prohibited, it was usually illicitly added to acetamiprid due to its particular insecticidal action and effect, so it was highly desirable to obtain a rapid and effective method to detect its concentration. Mid-Infrared spectroscopy (MIR) technique combined with two variable selection methods, interval combination optimization (ICO) and interval partial least squares (iPLS), were used to determinate the prohibited addition of fipronil. RESULTS: The full spectra for both ICO and iPLS were divided into forty equal-width intervals. Consequently, 45 and 135 characteristic variables were extracted from ICO and iPLS to establish the models. Compared with iPLS, the ICO model acquired a more suitable spectral region and as a result gained a higher prediction accuracy. Specifically, ICO method selected the characteristic wavelengths ascribed to C-F and C-N (in five-membered heterocyclics), iPLS chose the intervals associated with C-F and S=O. CONCLUSION: Results revealed that MIR combined with ICO could be efficiently used for rapid identification of illegal addition and had a great potential to provide on-site pesticide quality control.
关键词： pesticide,partial least squares,interval combination optimization,Mid-infrared spectroscopy,interval partial least squares
更新于2025-09-04 15:30:14
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A molecular design strategy to construct the near-infrared fluorescent probe for selectively sensing human cytochrome P450 2J2
摘要： Cytochrome P450 2J2 (CYP2J2), a key enzyme responsible for oxidative metabolism of various xenobiotics and endogenous compounds, participates in a diverse array of physiological and pathological processes in humans. Its biological role in tumorigenesis and cancer diagnosis remains poorly understood, owing to the lack of molecular tools suitable for real-time monitoring CYP2J2 in complex biological systems. Using molecular design principles we were able to modify the distance between the catalytic unit and metabolic recognition moiety, allowing us to develop a CYP2J2 selective fluorescent probe using a near-infrared fluorophore (E)-2-(2-(6-hydroxy-2, 3-dihydro-1H-xanthen-4-yl)vinyl)-3,3-dimethyl-1-propyl-3H-indol-1-ium iodide (HXPI). To improve the reactivity and isoform specificity, a self-immolative linker was introduced to the HXPI derivatives in order to better fit the narrow substrate channel of CYP2J2, the modification effectively shortened the spatial distance between the metabolic moiety (O-alkyl group) and catalytic center of CYP2J2. After screening a panel of O-alkylated HXPI derivatives, BnXPI displayed the best combination of specificity, sensitivity and applicability for detecting CYP2J2 in vitro and in vivo. Upon O-demethylation by CYP2J2, a self-immolative reaction occurred spontaneously via 1,6-elimination of p-hydroxybenzyl resulting in the release of HXPI. Allowing BnXPI to be successfully used to monitor CYP2J2 activity in real-time for various living systems including cells, tumor tissues, and tumor-bearing animals. In summary, our practical strategy could help the development of a highly specific and broadly applicable tool for monitoring CYP2J2, which offers great promise for exploring the biological functions of CYP2J2 in tumorigenesis.
关键词： Cytochrome P450 2J2,near-infrared fluorescent probe,real-time monitoring,molecular design,CYP2J2,tumorigenesis
更新于2025-09-04 15:30:14
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Recent advances in the synthesis of [ <i>a</i> ]-benzo-fused BODIPY fluorophores
摘要： This feature article summarizes the di?erent strategies for the synthesis of [a]-benzo-fused BODIPYs that have been reported in the literature until 2018. These p-extended BODIPYs are promising fluorophores for bio-imaging and organic photovoltaic applications due to both their attractive photophysical properties in the near-infrared area and their higher (photo)chemical stability compared to conventional bis-styryl derivatives. The four main strategies described in this review can be used to access either directly the expected [a]-benzo-fused BODIPYs or through the di-/tetra-hydroisoindole.
关键词： organic photovoltaic,fluorophores,near-infrared,BODIPY,bio-imaging
更新于2025-09-04 15:30:14
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A CRIRES-search for H <sub/>3</sub><sup>+</sup> emission from the hot Jupiter atmosphere of HD 209458 b
摘要： Close-in extrasolar giant planets are expected to cool their thermospheres by producing H+3 emission in the near-infrared (NIR), but simulations predict H+3 emission intensities that differ in the resulting intensity by several orders of magnitude. We want to test the observability of H+3 emission with CRIRES at the Very Large Telescope (VLT), providing adequate spectral resolution for planetary atmospheric lines in NIR spectra. We search for signatures of planetary H+3 emission in the L' band, using spectra of HD 209458 obtained during and after secondary eclipse of its transiting planet HD 209458 b. We searched for H+3 emission signatures in spectra containing the combined light of the star and, possibly, the planet. With the information on the ephemeris of the transiting planet, we derive the radial velocities at the time of observation and search for the emission at the expected line positions. We also apply a cross-correlation test to search for planetary signals and use a shift and add technique combining all observed spectra taken after secondary eclipse to calculate an upper emission limit. We do not find signatures of atmospheric H+3 emission in the spectra containing the combined light of HD 209458 and its orbiting planet. We calculate the emission limit for the H+3 line at 3953.0 nm [Q(1, 0)] to be 8.32 × 1018 W and a limit of 5.34 × 1018 W for the line at 3985.5 nm [Q(3, 0)]. Comparing our emission limits to the theoretical predictions suggests that we lack 1 to 3 magnitudes of sensitivity to measure H+3 emission in our target object. We show that under more favorable weather conditions the data quality can be improved significantly, reaching 5 × 1016 W for star-planet systems that are close to Earth. We estimate that pushing the detection limit down to 1015 W will be possible with ground-based observations with future instrumentation, for example, the European Extremly Large Telescope.
关键词： planetary systems,infrared: stars,stars: individual: HD 209458
更新于2025-09-04 15:30:14
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Uncertainties and biases of source masses derived from fits of integrated fluxes or image intensities
摘要： Fitting spectral distributions of total ?uxes or image intensities are two standard methods for estimating the masses of starless cores and protostellar envelopes. These mass estimates, which are the main source and basis of our knowledge of the origin and evolution of self-gravitating cores and protostars, are uncertain. It is important to clearly understand sources of statistical and systematic errors stemming from the methods and minimize the errors. In this model-based study, a grid of radiative transfer models of starless cores and protostellar envelopes was computed and their total ?uxes and image intensities were ?tted to derive the model masses. To investigate intrinsic e?ects related to the physical objects, all observational complications were explicitly ignored. Known true values of the numerical models allow assessment of the qualities of the methods and ?tting models, as well as the e?ects of nonuniform temperatures, far-infrared opacity slope, selected subsets of wavelengths, background subtraction, and angular resolutions. The method of ?tting intensities gives more accurate masses for more resolved objects than the method of ?tting ?uxes. With the latter, a ?tting model that assumes optically thin emission gives much better results than the one allowing substantial optical depths. Temperature excesses within the objects above the mass-averaged values skew their spectral shapes towards shorter wavelengths, leading to masses underestimated typically by factors 2?5. With a ?xed opacity slope deviating from the true value by a factor of 1.2, masses are inaccurate within a factor of 2. The most accurate masses are estimated by ?tting just two or three of the longest wavelength measurements. Conventional algorithm of background subtraction is a likely source of large systematic errors. The absolute values of masses of the unresolved or poorly resolved objects in star-forming regions are uncertain to within at least a factor of 2?3.
关键词： submillimeter: ISM,techniques: photometric,stars: formation,methods: data analysis,infrared: ISM,techniques: image processing
更新于2025-09-04 15:30:14
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Influence of carbon nanofibers electric conductivity on infrared extinction capability
摘要： Using method of moment, the calculating model of electric current distributing and scattered electric field for carbon nanofibers is established in this paper. Based on it, the expression of absorption cross section, scattering cross section and extinction cross section are got. The relationship between infrared extinction cross section of carbon nanofiber and electrical conductivity is analyzed and calculated by using Matlab. The results show that the infrared extinction cross section increases with electrical conductivity increase and peak value appeares when wavelength is longer than the length of carbon nanofiber. The electrical conductivity on peak value is related to wavelength.
关键词： carbon nanofibers,infrared extinction,absorption,scattering,extinction coefficient
更新于2025-09-04 15:30:14
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DenseFuse: A Fusion Approach to Infrared and Visible Images
摘要： In this paper, we present a novel deep learning architecture for infrared and visible images fusion problem. In contrast to conventional convolutional networks, our encoding network is combined by convolutional layers, fusion layer and dense block in which the output of each layer is connected to every other layer. We attempt to use this architecture to get more useful features from source images in encoding process. And two fusion layers(fusion strategies) are designed to fuse these features. Finally, the fused image is reconstructed by decoder. Compared with existing fusion methods, the proposed fusion method achieves state-of-the-art performance in objective and subjective assessment.
关键词： visible image,image fusion,infrared image,dense block,deep learning
更新于2025-09-04 15:30:14
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Verifying electromagnetic first layer effect on surface enhanced infrared absorption with evaporated gold nano island film
摘要： Infrared absorption enhancement is reported for a polyacrylic acid film deposited on evaporated gold film in normal transmission geometry. Comparison between absorption intensities measured with and without the self-assembled monolayer of p-nitrothiophenol demonstrates that the absorption intensities of polyacrylic acid are independent of the presence of a self-assembled monolayer. Results suggest that the first layer effect in the physical enhancement mechanism does not exist in this thermally evaporated island film.
关键词： First layer effect,Enhanced infrared absorption,Gold nano film
更新于2025-09-04 15:30:14