scholarly journals A photochemical determination of luminescence efficiency of upconverting nanoparticles

2019 ◽  
Vol 15 ◽  
pp. 2671-2677 ◽  
Author(s):  
Baptiste Amouroux ◽  
Clément Roux ◽  
Jean-Claude Micheau ◽  
Fabienne Gauffre ◽  
Christophe Coudret
Keyword(s):  
Near Infrared ◽  
Green Emission ◽  
Accurate Estimation ◽  
Luminescent Probes ◽  
Luminescence Efficiency ◽  
Visible Spectra ◽  
Precise Quantification ◽  
Infrared Excitation

Upconverting nanoparticles are a rising class of non-linear luminescent probes burgeoning since the beginning of the 2000’s, especially for their attractiveness in theranostics. However, the precise quantification of the light delivered remains a hot problem in order to estimate their impact on the biological medium. Sophisticated photophysical measurements under near infrared excitation have been developed only by few teams. Here, we present the first attempt towards a simple and cheap photochemical approach consisting of an actinometric characterization of the green emission of NaYF4:Yb,Er nanoparticles. Using the recently calibrated actinometer 1,2-bis(2,4-dimethyl-5-phenyl-3-thienyl)-3,3,4,4,5,5-hexafluoro-1-cyclopentene operating in the green region of the visible spectra, we propose a simple photochemical experiment to get an accurate estimation of the efficiency of these green-emitting “nanolamps”. The agreement of the collected data with the previous published results validates this approach.

scholarly journals A photochemical determination of luminescence efficiency of upconverting nanoparticles

2019 ◽  
Author(s):  
Baptiste AMOUROUX ◽  
Clément ROUX ◽  
Jean-Claude MICHEAU ◽  
Fabienne GAUFFRE ◽  
Christophe M COUDRET
Keyword(s):  
Green Emission ◽  
Accurate Estimation ◽  
Luminescent Probes ◽  
Luminescence Efficiency ◽  
Visible Spectra ◽  
Non Linear ◽  
Precise Quantification ◽  
The Impact

Upconverting nanoparticles are a rising class of non-linear luminescent probes burgeoning since the beginning of the 2000’s, especially for their attractiveness in biology. However, the precise quantification of the light delivered remains a hot problem in order to estimate the impact in biology, resulting in the development by a few teams of sophisticated photophysical measurements (operable under NIR excitation). Here, we present the first attempt towards a simple and cheap photochemical approach consisting of a pseudo-actinometric characterization of the green emission of NaYF4:Yb,Er. Using the recently calibrated actinometer 1,2-bis(2,4-dimethyl-5-phenyl-3-thienyl)-3,3,4,4,5,5-hexafluoro-1-cyclopentene operating in the green region of the visible spectra, we propose simple photochemical experiments to get an accurate estimation of the efficiency of these green-emitting “nanolamps”. The agreement of the collected data with the previous published results validates this approach.

scholarly journals Measuring specific surface area of snow by near-infrared photography

2006 ◽  
Vol 52 (179) ◽  
pp. 558-564 ◽  
Author(s):  
Margret Matzl ◽  
Martin Schneebeli
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Near Infrared ◽  
Two Dimensions ◽  
Chemical Models ◽  
Snow Stratigraphy ◽  
Physical And Chemical

AbstractThe specific surface area (SSA) is considered an essential microstructural parameter for the characterization of snow. Photography in the near-infrared (NIR) spectrum is sensitive to the SSA. We calculated the snow reflectance from calibrated NIR images of snow-pit walls and measured the SSA of samples obtained at the same locations. This new method is used to map the snow stratigraphy. The correlation between reflectance and SSA was found to be 90%. Calibrated NIR photography allows quantitative determination of SSA and its spatial variation in a snow profile in two dimensions within an uncertainty of 15%. In an image covering 0.5–1.0 m2, even layers of 1mm thickness can be documented and measured. Spatial maps of SSA are an important tool in initializing and validating physical and chemical models of the snowpack.

Heat Generation in Laser Irradiated Tissue

1989 ◽  
Vol 111 (1) ◽  
pp. 62-68 ◽  
Author(s):  
A. J. Welch ◽  
J. A. Pearce ◽  
K. R. Diller ◽  
G. Yoon ◽  
W. F. Cheong
Keyword(s):  
Heat Source ◽  
Heat Generation ◽  
Near Infrared ◽  
Scattered Light ◽  
Incident Beam ◽  
Accurate Estimation ◽  
Optical Parameters ◽  
Infrared Wavelengths ◽  
Improved Model

Many medical applications involving lasers rely upon the generation of heat within the tissue for the desired therapeutic effect. Determination of the absorbed light energy in tissue is difficult in many cases. Although UV wavelengths of the excimer laser and 10.6 μm wavelength of the CO2 laser are absorbed within the first 20 μm of soft tissue, visible and near infrared wavelengths are scattered as well as absorbed. Typically, multiple scattering is a significant factor in the distribution of light in tissue and the resulting heat source term. An improved model is presented for estimating heat generation due to the absorption of a collimated (axisymmetric) laser beam and scattered light at each point r and z in tissue. Heat generated within tissue is a function of the laser power, the shape and size of the incident beam and the optical properties of the tissue at the irradiation wavelength. Key to the calculation of heat source strength is accurate estimation of the light distribution. Methods for experimentally determining the optical parameters of tissue are discussed in the context of the improved model.

scholarly journals Field Spectroscopy Applied to the Kaolinite Polytypes Identification

2021 ◽  
Vol 6 (1) ◽  
pp. 16
Author(s):  
Andrea García-Vicente ◽  
Adrián Lorenzo ◽  
Juan Morales ◽  
Emilia García-Romero ◽  
Mercedes Suárez
Keyword(s):  
Near Infrared ◽  
Short Wave ◽  
Second Derivative ◽  
X Ray Diffraction ◽  
Components Analysis ◽  
Xrd Patterns ◽  
Good Agreement

A detailed characterization of a group of kaolin samples rich in some minerals of the kaolinite group was done. The mineralogical and structural characterization was conducted by X-ray diffraction (XRD) together with the study of the spectroscopy response in visible-near infrared and short wave (VNIR–SWIR), and the main objective was the determination of kaolinite polytypes. The XRD patterns group the samples according to the kaolinite polytype into five kaolinites, two dickites and six halloysites. Diagnostic peaks for kaolinite, dickite polytypes and halloysite were identified in the spectra and in the second derivative of the SWIR region. The position and intensity of the peaks in the second derivative were statistically treated with the aim of classifying the spectra according to the polytype. In good agreement with the XRD results, the statistical analysis of the spectroscopic data, both by cluster analysis and by principal components analysis, allows an unequivocal classification of the samples according to the polytype from their VNIR–SWIR spectra.

Characterization of Impressed Current Technique to Model Corrosion of Reinforcement in Concrete

2020 ◽  
Vol 11 (1) ◽  
pp. 93-99
Author(s):  
Abu Zakir Morshed ◽  
Sheikh Shakib ◽  
Tanzim Jahin
Keyword(s):  
Immersion Time ◽  
Chloride Content ◽  
Engineering Science ◽  
Coastal Regions ◽  
Faraday’S Law ◽  
Current Technique ◽  
Corrosion Cell ◽  
Impressed Current

Corrosion of reinforcement is an important durability concern for the structures exposed to coastal regions. Since corrosion of reinforcement involves long periods of time, impressed current technique is usually used to accelerate the corrosion of reinforcement in laboratories. Characterization of impressed current technique was the main focus of this research,which involved determination of optimum chloride content and minimum immersion time of specimens for which the application of Faraday’s law could be efficient. To obtain optimum chloride content, the electrolytes in the corrosion cell were prepared similar to that of concrete pore solutions. Concrete prisms of 200 mm by 200 mm by 300 mm were used to determine the minimum immersion time for saturation. It was found that the optimum chloride content was 35 gm/L and the minimum immersion time for saturation was 140 hours. Accounting the results, a modified expression based on Faraday’s law was proposed to calculate weight loss due to corrosion. Journal of Engineering Science 11(1), 2020, 93-99

The Determination of Sense via Deleuze and Blanchot: Paradoxes of the Habitual, the Immemorial, and the Eternal Return

2008 ◽  
Vol 2 (2) ◽  
pp. 155-177 ◽  
Author(s):  
Eugene Brently Young
Keyword(s):  
Eternal Return

Eternal return is the paradox that accounts for the interplay between difference and repetition, a dynamic at the heart of Deleuze's philosophy, and Blanchot's approach to this paradox, even and especially through what it elides, further illuminates it. Deleuze draws on Blanchot's characterisations of difference, forgetting, and the unlivable to depict the ‘sense’ produced via eternal return, which, for Blanchot, is where repetition implicates or ‘carries’ pure difference. However, for Deleuze, difference and the unlivable are also developed by the living repetition or ‘contraction’ of habit, which results in his distinctive characterization of ‘force’, ‘levity’, and sense in eternal return.

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