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Black phosphorous sensitized TiO <sub/>2</sub> mesocrystals photocatalyst for hydrogen evolution with visible and near-infrared light irradiation
摘要： Wide absorption from ultraviolet (UV) to near-infrared (NIR) region and enhanced charge separation are two main requirements for promising semiconductor photocatalysts. Here, we studied visible-NIR driven photocatalytic hydrogen evolution over black phosphorus nanosheets/TiO2 mesocrystals loaded with Pt heterostructure (BP NS/ Pt (3 wt%)/TMC TMC). BP NS/Pt (3 wt%)/TMC can harvest photons from UV to NIR and simultaneously has enhanced charge separation to increase the generation of electrons for photocatalytic reduction of water. BP NS/Pt (3 wt%)/TMC exhibited photocatalytic H2 evolution rates of 1.9 and 0.41 μmol h-1 under visible (λ> 420 nm (420-1800 nm)) and NIR (λ> 780 nm (780-1800 nm) irradiation, respectively, compared with 0.3 and 0.10 μmol h-1 for BP NS/Pt (3 wt%)/P25. Moreover, a comparative study was made to examine the effect of thickness of BP NS on the photocatalytic H2 evolution. Femtosecond time-resolved diffused reflectance spectroscopy (fs-TRDRS) was integrated together with photoelectrochemical measurement to shed the light on the importance of charge transfer and separation, confirming that decreasing the thickness of BP NS enhances electron injection from BP NS to TMC to increase the photocatalytic activity.
关键词： hydrogen evolution,Black phosphorus,visible-light photocatalyst,charge carriers dynamics,TiO2 mesocrystals,femtosecond time-resolved diffuse reflectance
更新于2025-11-19 16:51:07
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Monte Carlo based model for diffuse reflectance from turbid media for the diagnosis of epithelial dysplasia
摘要： Diffuse reflectance from biological tissue has been widely used in diagnostic oncology for characterizing biochemical and morphological changes in epithelial tissue. However, computational complexity and time consumption involved in the extraction of absorption and scattering properties of tissues from diffuse reflectance reduce its potentiality for the effective diagnosis in a clinical setup. In this regard, a simple and accurate empirical equation for diffuse reflectance from a turbid medium was developed. A diffuse reflectance lookup table was generated using Monte Carlo simulations of all the optical properties typical of soft tissues in the visible and near infrared region of the spectrum for a semi-infinite medium. The generated lookup table was used to extract an empirical equation for diffuse reflectance using the surface fitting method. The proposed equation was tested with simulations and tissue phantom validation studies. The accuracy of the proposed empirical equation is tenfold higher than the diffusion approximation method. The uniqueness of the present method lies in its reliability even at extremities.
关键词： turbid medium,empirical model,Monte Carlo,epithelial dysplasia,diffuse reflectance
更新于2025-09-23 15:23:52
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Promising red emission from functionalized Polypyrrole/CaTiO3:Eu3+ nano-composites for photonic applications
摘要： CaTiO3:Eu3+ luminescent nanoparticles (NPs) and Ppy/CaTiO3:Eu3+ nanocomposites (NCs) are synthesized via combustion and solution casting techniques respectively and their structural and optical properties are investigated. The powder X-ray diffraction patterns of the as-formed products show single orthorhombic phase. The crystallite size measurement is assessed utilizing Scherrer's technique and observed to be in the range of 40–45 nm. The impact of Eu3+ ions on luminescence properties of the produced nanophosphors is examined the outcomes are given in detail. The phosphors displayed splendid red emission at 398 nm excitation. The emission peaks observed at 540, 593, 615, 653, 696 and 706 nm (5D0→7Fj = 0, 1, 2, 3, 4, 5) are assigned to Eu3+ ions transitions. The electronic transition equivalent to 5D0→7F2 (615 nm) is robust than the magnetic dipole transition 5D0→7F1 of Eu3+ ions (596 nm). The CIE chromaticity co-ordinates are ascertained from emanation spectra, the obtained values are very close to NTSC standard value of red emission. Hence, the present phosphors are exceedingly valuable for display applications. The obtained results demonstrate that Ppy-assisted solution casting is an effective methodology for the synthesis of rare-earth doped CaTiO3:Eu3+ nanocomposites (NCs).
关键词： Diffuse reflectance,Microbial activity,Nanocomposites,Color diagrams,Polypyrrole
更新于2025-09-23 15:23:52
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Investigation of gamma irradiation effects on the properties of CdS/p-Si heterostructure
摘要： Cadmium sulfide (CdS) thin films were deposited on p-type Si substrate by thermal evaporation to fabricate the CdS/p-Si heterojunction. Gamma irradiation has been used to modify the microstructural, optical and electrical characteristics of CdS/p-Si heterojunction of various doses in the range (0–80 kGy). X-ray diffraction measurements of the gamma irradiated show the reduction in crystallinity of the CdS thin films. While scanning electron microscope images depicted the average CdS particle size was found to be increased with increasing the gamma irradiation dose. Photoluminescence results revealed that at the specific dose of gamma irradiation was found to create the yellow emission in interstitial sites to the valence band. The I–V characteristics showed the current transport properties effected by the different gamma doses. The values of barrier height, saturation current and ideality factor for the CdS/p-Si heterostructure varied due to the causes like inhomogeneities in the interfacial, defect density, charge distribution on interfacial and interfacial layer thickness after gamma irradiation. The gamma irradiation induced effects and the possible mechanism in CdS/p-Si heterojunction is discussed.
关键词： Heterostructure,Diffuse reflectance,Photoluminescence,Gamma irradiation,Thermal evaporation
更新于2025-09-23 15:23:52
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Green method by diffuse reflectance infrared spectroscopy and spectral region selection for the quantification of sulphamethoxazole and trimethoprim in pharmaceutical formulations
摘要： An alternative method for the quantification of sulphametoxazole (SMZ) and trimethoprim (TMP) using diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS) and partial least square regression (PLS) was developed. Interval Partial Least Square (iPLS) and Synergy Partial Least Square (siPLS) were applied to select a spectral range that provided the lowest prediction error in comparison to the full-spectrum model. Fifteen commercial tablet formulations and forty-nine synthetic samples were used. The ranges of concentration considered were 400 to 900 mg g-1 SMZ and 80 to 240 mg g-1 TMP. Spectral data were recorded between 600 and 4000 cm-1 with a 4 cm-1 resolution by Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS). The proposed procedure was compared to high performance liquid chromatography (HPLC). The results obtained from the root mean square error of prediction (RMSEP), during the validation of the models for samples of sulphamethoxazole (SMZ) and trimethoprim (TMP) using siPLS, demonstrate that this approach is a valid technique for use in quantitative analysis of pharmaceutical formulations. The selected interval algorithm allowed building regression models with minor errors when compared to the full spectrum PLS model. A RMSEP of 13.03 mg g-1 for SMZ and 4.88 mg g-1 for TMP was obtained after the selection the best spectral regions by siPLS.
关键词： green analytical method,diffuse reflectance infrared Fourier transform spectroscopy,interval partial least squares (iPLS),chemometrics,synergy partial least squares (siPLS),high performance liquid chromatography
更新于2025-09-23 15:22:29
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Towards an on-chip optical microsystem for spectroscopic detection of gastrointestinal dysplasia
摘要： This paper presents a CMOS optical microsystem with a 4×4 photodiodes array and their readout electronics, based on 16 light-to-frequency converters, and 16 high selective optical filters, for spectrophotometric measurement of diffuse reflectance and fluorescence signals, applied to the detection of gastrointestinal dysplasia. The photodiodes array is based on n+/p-epilayer junction silicon photodiodes. Their readout electronics outputs a digital signal, with a frequency proportional to the photodiode current, featuring a sensitivity of 26 Hz/nA at 550 nm, a spectral resolution of 9 MHz and a power consumption of 1 mW. The optical filters are based on 16 thin-film narrow-band Fabry-Perot resonators, in which dielectric mirrors are used. They feature high transmittances and low full-width-half-maximum. Experimental measurements, using phantoms representative of the main absorbing, scattering and fluorescence properties of gastrointestinal tissues, proved the viability of the CMOS optical microsystem with the optical filters to extract those signals, when comparing the obtained results with commercial equipment. The implemented apparatus is ready to be used as a portable system on a surgery room to verify the total removing of gastrointestinal cancer tissue. Moreover, the developed approach is a step forward in the implementation of a gastrointestinal dysplasia detection miniaturized tool.
关键词： Fluorescence,CMOS optical microsystem,Optical filters,Gastrointestinal dysplasia,Diffuse reflectance
更新于2025-09-23 15:21:01
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Diffuse Reflectance Spectroscopy (Vis-Nir-Swir) as a Promising Tool for Blue Carbon Quantification in Mangrove Soils: A Case of Study in Tropical Semiarid Climatic Conditions
摘要： The assessment of the soil organic carbon (SOC) stocks in mangrove ecosystems is essential for coastal management activities seeking the mitigation of CO2 emissions. However, the wet chemical analysis conventionally used to quantify SOC may overestimate SOC content due to oxidation of reduced compounds. This work focused on the use of diffuse reflectance spectroscopy (DRS) for predicting SOC in mangrove forest areas. When used properly, DRS may be, in some cases, a more accurate and more efficient method for the determination of SOC in mangrove soils than conventional analytical approaches. Furthermore, variable selection may simplify and improve prediction accuracy, reducing collinearity in the dataset used and allowing better SOC quantification through more interpretable and robust models.
关键词： Tropical semiarid climatic conditions,Mangrove soils,Vis-NIR-SWIR,Blue Carbon,Diffuse reflectance spectroscopy
更新于2025-09-23 15:21:01
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High-speed light source depth estimation using spatially-resolved diffuse imaging
摘要： We describe a system for high-speed depth estimation of a light source embedded in a scattering medium. A polynomial model estimates source depth from the spatially-resolved, diffuse reflectance profile measured with a fibre optic probe on the surface of a scattering medium. A dataset of Monte Carlo reflectance profiles is generated over a range of typical optical properties and the model is fit to the simulated reflectance at four detector locations. The model accounts for a source depth up to 15 mm. Cross-validation using the Monte Carlo dataset produced a root mean square error of 0.12 mm. Experimental reflectance data is acquired with the detector probe, which consists of four optical fibres mounted in a black acetal plastic disk. The optical fibres are coupled into avalanche photodiodes for high-speed acquisition of the reflectance profile. When applied to measurements from a tissue-mimicking phantom with an embedded light source, the polynomial model generates depth estimates within 2 mm of the true depth, up to a source depth of 15 mm.
关键词： source location,Monte Carlo simulation,tissue optics,turbid media,diffuse reflectance
更新于2025-09-19 17:15:36
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Towards an optical diagnostic system for otitis media using a combination of otoscopy and spectroscopy
摘要： An improved method, where conventional otoscope investigation of human suspicious otitis media is combined with diffuse reflectance spectroscopy and gas in scattering media absorption spectroscopy (GASMAS) is being developed. Otitis media is one of the most common infectious diseases in children, whose Eustachian tube connecting the middle ear with the nasal cavity is more horizontal than for adults, which leads to impaired fluid drainage. At present, the use of an otoscope to visually observe possible changes in the tympanic membrane appearance is the main diagnostics method for otitis media. Inaccurate diagnosis related to similar symptoms, and the difficulty for small children to describe the condition experienced, frequently leads to over-prescription of antibiotics and alarming increase in bacterial resistance development. More accurate diagnostic methods are highly desirable. Diffuse reflectance spectroscopy is a non-invasive quantitative spectroscopic technique that enables to objectively quantify changes in the hemoglobin content of the tympanic membrane related to inflammation. If an infection is present, the ventilatory function of the Eustachian tube is frequently impaired and the middle-ear cavity will be filled with fluid. GASMAS, a non-invasive detection method, can non-invasively determine if gas is replaced by fluid in the middle-ear cavity.
关键词： otitis media,otoscope,diffuse reflectance spectroscopy,diagnostics,GASMAS,ear infection
更新于2025-09-19 17:15:36
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Identification of tea varieties by mid‐infrared diffuse reflectance spectroscopy coupled with a possibilistic fuzzy c‐means clustering with a fuzzy covariance matrix
摘要： Mid-infrared diffuse reflectance spectroscopy was used to rapidly and nondestructively identify tea varieties together with the proposed possibilistic fuzzy c-means (PFCM) clustering with a fuzzy covariance matrix. The mid-infrared diffuse reflectance spectra of 96 tea samples with three different varieties (Emeishan Maofeng, Level 1, and Level 6 Leshan trimeresurus) were acquired using the FTIR-7600 infrared spectrometer. First, multiplicative scatter correction was implemented to pretreat the spectral data. Second, principal component analysis was employed to compress the mid-infrared diffuse reflectance spectral data after preprocessing. Third, linear discriminant analysis was utilized for extracting the identification information required by the fuzzy clustering algorithms. Ultimately, the fuzzy c-means (FCM) clustering, the allied fuzzy c-means (AFCM) clustering, the PFCM clustering, and the PFCM clustering with a fuzzy covariance matrix were used to cluster the processed spectral data, respectively. The highest identification accuracy of the PFCM clustering with a fuzzy covariance matrix reached at 100% compared with those of FCM (96.7%), AFCM (94.9%), PFCM (96.3%), and partial least squares discrimination analysis (PLS-DA) algorithm (33.3%). It is sufficiently demonstrated that the mid-infrared diffuse reflectance spectroscopy coupled with the PFCM clustering with a fuzzy covariance matrix was a valid method for identifying tea varieties.
关键词： possibilistic fuzzy c-means clustering,tea varieties,Mid-infrared diffuse reflectance spectroscopy,fuzzy covariance matrix,nondestructive detection
更新于2025-09-11 14:15:04