F112 Visualization of exothermic chemical reactions in microchannels using a near-infrared two-wavelength imaging method : Absorption spectra and two-wavelength images of aqueous solutions of HCl and NaOH

AbstractWe present an overview of recent results on optical coherence tomography with the use of extreme ultraviolet and soft X-ray radiation (XCT). XCT is a cross-sectional imaging method that has emerged as a derivative of optical coherence tomography (OCT). In contrast to OCT, which typically uses near-infrared light, XCT utilizes broad bandwidth extreme ultraviolet (XUV) and soft X-ray (SXR) radiation (Fuchs et al in Sci Rep 6:20658, 2016). As in OCT, XCT’s axial resolution only scales with the coherence length of the light source. Thus, an axial resolution down to the nanometer range can be achieved. This is an improvement of up to three orders of magnitude in comparison to OCT. XCT measures the reflected spectrum in a common-path interferometric setup to retrieve the axial structure of nanometer-sized samples. The technique has been demonstrated with broad bandwidth XUV/SXR radiation from synchrotron facilities and recently with compact laboratory-based laser-driven sources. Axial resolutions down to 2.2 nm have been achieved experimentally. XCT has potential applications in three-dimensional imaging of silicon-based semiconductors, lithography masks, and layered structures like XUV mirrors and solar cells.

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Spectral Probe for Electron Transfer and Addition Reactions of Azide Radicals with Substituted Quinoxalin-2-Ones in Aqueous Solutions

International Journal of Molecular Sciences ◽

10.3390/ijms22020633 ◽

2021 ◽

Vol 22 (2) ◽

pp. 633

Author(s):

Konrad Skotnicki ◽

Slawomir Ostrowski ◽

Jan Cz. Dobrowolski ◽

Julio R. De la Fuente ◽

Alvaro Cañete ◽

...

Keyword(s):

Electron Transfer ◽

Aqueous Solutions ◽

Absorption Spectra ◽

Density Functional ◽

Reduction Potential ◽

Biological Significance ◽

Radical Cations ◽

Basis Sets ◽

Double Bonds ◽

Reduction Potentials

The azide radical (N3●) is one of the most important one-electron oxidants used extensively in radiation chemistry studies involving molecules of biological significance. Generally, it was assumed that N3● reacts in aqueous solutions only by electron transfer. However, there were several reports indicating the possibility of N3● addition in aqueous solutions to organic compounds containing double bonds. The main purpose of this study was to find an experimental approach that allows a clear assignment of the nature of obtained products either to its one-electron oxidation or its addition products. Radiolysis of water provides a convenient source of one-electron oxidizing radicals characterized by a very broad range of reduction potentials. Two inorganic radicals (SO4●−, CO3●−) and Tl2+ ions with the reduction potentials higher, and one radical (SCN)2●− with the reduction potential slightly lower than the reduction potential of N3● were selected as dominant electron-acceptors. Transient absorption spectra formed in their reactions with a series of quinoxalin-2-one derivatives were confronted with absorption spectra formed from reactions of N3● with the same series of compounds. Cases, in which the absorption spectra formed in reactions involving N3● differ from the absorption spectra formed in the reactions involving other one-electron oxidants, strongly indicate that N3● is involved in the other reaction channel such as addition to double bonds. Moreover, it was shown that high-rate constants of reactions of N3● with quinoxalin-2-ones do not ultimately prove that they are electron transfer reactions. The optimized structures of the radical cations (7-R-3-MeQ)●+, radicals (7-R-3-MeQ)● and N3● adducts at the C2 carbon atom in pyrazine moiety and their absorption spectra are reasonably well reproduced by density functional theory quantum mechanics calculations employing the ωB97XD functional combined with the Dunning’s aug-cc-pVTZ correlation-consistent polarized basis sets augmented with diffuse functions.

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Using near infrared measurements to evaluate NaCl and KCl in water

Journal of Near Infrared Spectroscopy ◽

10.1177/0967033518821834 ◽

2019 ◽

Vol 27 (2) ◽

pp. 147-155

Author(s):

Reisha D Peters ◽

Scott D Noble

Keyword(s):

Aqueous Solutions ◽

Near Infrared ◽

Average Error ◽

Spectral Measurements ◽

Salt Solutions ◽

Saturation Point ◽

Test Set ◽

Solution Type ◽

All Solutions ◽

Infrared Measurements

Spectral differences between aqueous solutions of NaCl and KCl have received minimal attention in previous research due to strong similarities between the two salts and the lack of motivation to differentiate between them. Correlations between salinity and absorbance have been developed previously with varying degrees of linearity but have not been tested to saturation. This work will demonstrate that correlating spectral measurements and the concentration of NaCl and KCl in water can be extended up to the saturation point of both salts and that solutions of these salts with unknown concentrations can be distinguished. Spectral data for samples of NaCl and KCl in single-salt solutions were collected up to saturation and correlations were developed for differentiating between solutions of the two species. These correlations were able to correctly identify the solution type for all solutions in the test set and estimate their concentrations with an average error of 0.9%.

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Aggregation-induced emission nanoparticles for in vivo three-photon fluorescence microscopic rat brain angiography

Journal of Innovative Optical Health Sciences ◽

10.1142/s1793545819500123 ◽

2019 ◽

Vol 12 (06) ◽

pp. 1950012 ◽

Cited By ~ 2

Author(s):

Hequn Zhang ◽

Weisi Xie ◽

Ming Chen ◽

Liang Zhu ◽

Zhe Feng ◽

...

Keyword(s):

Rat Brain ◽

Blood Vessels ◽

Laser Scanning ◽

Near Infrared ◽

Brain Disease ◽

Laser Scanning Microscopy ◽

High Signal ◽

Imaging Method ◽

Photon Fluorescence

Rodents are popular biological models for physiological and behavioral research in neuroscience and rats are better models than mice due to their higher genome similarity to human and more accessible surgical procedures. However, rat brain is larger than mice brain and it needs powerful imaging tools to implement better penetration against the scattering of the thicker brain tissue. Three-photon fluorescence microscopy (3PFM) combined with near-infrared (NIR) excitation has great potentials for brain circuits imaging because of its abilities of anti-scattering, deep-tissue imaging, and high signal-to-noise ratio (SNR). In this work, a type of AIE luminogen with red fluorescence was synthesized and encapsulated with Pluronic F-127 to make up form nanoparticles (NPs). Bright DCDPP-2TPA NPs were employed for in vivo three-photon fluorescent laser scanning microscopy of blood vessels in rats brain under 1550[Formula: see text]nm femtosecond laser excitation. A fine three-dimensional (3D) reconstruction up to the deepness of 600[Formula: see text][Formula: see text]m was achieved and the blood flow velocity of a selected vessel was measured in vivo as well. Our 3PFM deep brain imaging method simultaneously recorded the morphology and function of the brain blood vessels in vivo in the rat model. Using this angiography combined with the arsenal of rodent’s brain disease, models can accelerate the neuroscience research and clinical diagnosis of brain disease in the future.

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