The Impact of Laser Evolution on Modern Fluorescence Spectroscopy

2016 ◽  
pp. 163-178
Author(s):  
Jianhua Xu ◽  
Jay R. Knutson
Keyword(s):  
Fluorescence Spectroscopy ◽  
The Impact

scholarly journals Influence of Fluorine on Clinker burnability and mechanical properties of CPA Moroccan cement

2018 ◽  
Vol 149 ◽  
pp. 01075 ◽  
Author(s):  
A. Bouregba ◽  
A. Diouri ◽  
B. Elghattas ◽  
A. Boukhari ◽  
T. Guedira
Keyword(s):  
Mechanical Properties ◽  
Fluorescence Spectroscopy ◽  
Calcium Fluoride ◽  
X Ray Diffraction ◽  
Free Lime ◽  
X Ray ◽  
The Subject ◽  
Lower Temperature ◽  
The Impact ◽  
Cement Raw Mix

It has been found that the addition of certain components, despite their low concentration in raw mix, may accelerate and enhance the reactivity of the cement raw mix. The utilization of mineralizers to facilitate and quicken the process of clinkerization backpedals numerous years, the concept of using such mineralizers to burn normal raw mixes at a much lower temperature with the end goal of decreasing the fuel necessities of the furnace and to enhance the cement proprieties has become to be seriously considered over the most recent couple of years. The subject of this paper is to investigate the impact of calcium fluoride as mineralizer on addition during the clinkerization process of industrial raw mixtures and its effect on chemical, mineralogical, and mechanical properties of CPA Moroccan cement. Five different raw meals were utilized and were burned with 2% of calcium fluoride. The resulting clinker was analyzed by X-ray diffraction (XRD) and fluorescence spectroscopy to determine the chemical phases of the obtained clinker, and the mechanical properties of resulting CPA cement were determined. The results show that the addition of 2% of CaF2 to the clinker raw meal induced a decrease in the burning temperature and free lime, while improving the clinker phase formation and the mechanical properties of obtained cement.

scholarly journals Laser-Induced Fluorescence Spectroscopy in the Diagnosis of Tissue Hypoxia (Review)

2019 ◽  
Vol 15 (6) ◽  
pp. 50-61
Author(s):  
Anastasiya S. Babkina
Keyword(s):  
Fluorescence Spectroscopy ◽  
Clinical Medicine ◽  
Laser Induced Fluorescence ◽  
Tissue Hypoxia ◽  
Endogenous Factors ◽  
Tissue Ischemia ◽  
Promising Area ◽  
Reduced Nicotinamide Adenine Dinucleotide ◽  
The Impact

The aim of review is to discuss the results of studies on diagnosis of tissue hypoxia by laser-induced spectroscopy, as well as to identify promising trends and prospects of this technique for its further application in experimental and clinical medicine.The review presents the findings of studies of the fluorescence intensity of endogenous fluorophore molecules (reduced nicotinamide adenine dinucleotide, oxidized flavin adenine dinucleotide) as markers of ischemic injury of internal organs (brain, heart, liver, kidneys, etc.). The principles of fluorescence laser-induced spectroscopy in vivo are discussed. The historical aspects of the subject are also covered. The results of the use of the technique in experimental and clinical studies of tissue hypoxia and ischemia are shown. Difficulties in interpreting the intensity values of autofluorescent signal of the studied molecules are revealed. It was noted that the tissue autofluorescence in a long-term anoxia remains unknown, and there are no structured ideas about the impact of exogenous and endogenous factors on autofluorescence intensity.In conclusion, the use of laser-induced fluorescence spectroscopy to diagnose tissue ischemia is a promising area of experimental and clinical medicine, which still has various unresolved issues, despite a large number of studies in this domain.

scholarly journals Evidence of high Sr/Ca in a Middle Jurassic murolith coccolith species

2020 ◽  
Author(s):  
Baptiste Suchéras-Marx ◽  
Fabienne Giraud ◽  
Alexandre Simionovici ◽  
Rémi Tucoulou ◽  
Isabelle Daniel
Keyword(s):  
Fluorescence Spectroscopy ◽  
Middle Jurassic ◽  
Photic Zone ◽  
X Ray ◽  
Continuous Record ◽  
The Common ◽  
Geochemical Analyses ◽  
Set Up ◽  
The Impact ◽  
Very High

Paleoceanographical reconstructions are often based on microfossil geochemical analyses. Coccoliths are the most ancient, abundant and continuous record of pelagic photic zone calcite producer organisms. Hence, they could be valuable substrates for geochemically based paleoenvironmental reconstructions but only Sr/Ca is exploited even if it remains poorly understood. For example, some murolith coccoliths species have very high Sr/Ca compared to the common 1-4 mmol/mol recorded in placolith coccoliths. In this study, we analyzed the elemental composition of the Middle Jurassic murolith Crepidolithus crassus by synchrotron-based nanoXRF (X-ray Fluorescence Spectroscopy) mapping focusing on Sr/Ca and compared the record to two placolith species, namely Watznaueria contracta and Discorhabdus striatus. In C. crassus, Sr/Ca is more than ten times higher than in both placoliths and seems higher in the proximal cycle. By comparison with the placoliths analyzed in the same analytical set-up and from the same sample, we exclude the impact of the diagenesis and seawater Sr/Ca to explain the high Sr/Ca in C. crassus. Based on comparisons to Pontosphaera discopora and Scyphosphaera apsteinii which also have high Sr/Ca, it seems more likely that high Sr/Ca in C. crassus is either due to the vertical elongation of the R-units of the proximal cycle or related to the action of the special polysaccharide controlling the growth of those vertically elongated R-units that may have affinities to Sr2+. In order to apply the Sr/Ca proxy to muroliths, further investigations are needed on cultured coccoliths.

scholarly journals Excitation-emission fluorescence matrix acquired from glutathione capped CdSeS/ZnS quantum dots in combination with chemometric tools for pattern-based sensing of neurotransmitters

2021 ◽  
Vol 188 (10) ◽  
Author(s):  
Klaudia Głowacz ◽  
Marcin Drozd ◽  
Patrycja Ciosek-Skibińska
Keyword(s):  
Quantum Dots ◽  
Fluorescence Spectroscopy ◽  
Least Squares ◽  
Partial Least Squares ◽  
Fluorescence Signal ◽  
Response Patterns ◽  
Least Squares Regression ◽  
Sensing Element ◽  
Fluorescent Response ◽  
The Impact

AbstractThe presented work concerns pattern-based sensing with quantum dots for the identification and quantification of neurotransmitters by means of excitation-emission fluorescence spectroscopy (2D fluorescence). In the framework of this study, glutathione capped CdSeS/ZnS nanocrystals were used as non-specific nanoreceptors capable of differentiated interaction with neurotransmitters. The pattern-based sensing with QDs was realized by using excitation-emission fluorescence spectroscopy to provide analyte-specific multidimensional optical information. These characteristic fluorescent response patterns were processed by unfolded partial least squares–discriminant analysis, showing that satisfactory identification of all investigated neurotransmitters: dopamine, norepinephrine, epinephrine, serotonin, GABA, and acetylcholine, can be achieved through the proposed sensing strategy. The impact of the considered fluorescence signal (datum, i.e. zeroth-order data acquired per sample; spectrum, i.e. first-order data acquired per sample; excitation-emission matrix, i.e. second-order data acquired per sample) on the sensing capability of glutathione capped QDs was also verified. The best performance parameters such as accuracy, precision, sensitivity, and specificity were obtained using excitation-emission matrices (88.9–93.3%, 0.93–0.95, 0.89–0.93, and 0.99–1.00, respectively). Thus, it was revealed that excitation-emission fluorescence spectroscopy may improve the recognition of neurotransmitters while using only one type of nanoreceptor. Furthermore, is was demonstrated that the proposed excitation-emission fluorescence spectroscopy assisted QD assay coupled with unfolded partial least squares regression can be successfully utilized for quantitative determination of catecholamine neurotransmitters at the micromolar concentration range with R2 in the range 0.916–0.987. Consequently, the proposed sensing strategy has the potential to significantly simplify the sensing element and to expand the pool of bioanalytes so far detectable with the use of QDs. Graphical abstract

scholarly journals Fluorescence Spectroscopy Study of Protoporphyrin IX in Optical Tissue Simulating Liquid Phantoms

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2105
Author(s):  
Huihui Lu ◽  
Francesco Floris ◽  
Marc Rensing ◽  
Stefan Andersson-Engels
Keyword(s):  
Fluorescence Spectroscopy ◽  
Protoporphyrin Ix ◽  
Biological Tissues ◽  
Disease Diagnosis ◽  
Tween 20 ◽  
Dimethyl Formamide ◽  
Background Medium ◽  
Clinical Procedures ◽  
Biomedical Device ◽  
The Impact

Fluorescence spectroscopy has been extensively investigated for disease diagnosis. In this framework, optical tissue phantoms are widely used for validating the biomedical device system in a laboratory environment outside of clinical procedures. Moreover, it is fundamental to consider that there are several scattering components and chromophores inside biological tissues and the interplay between scattering and absorption may result in a distortion of the emitted fluorescent signal. In this work, the photophysical behaviour of a set of liquid, tissue-like phantoms containing different compositions was analysed: phosphate buffer saline (PBS) was used as the background medium, low fat milk as a scatterer, Indian ink as an absorber and protoporphyrin IX (PpIX) dissolved in dimethyl formamide (DMF) as a fluorophore. We examined the collected data in terms of the impact of surfactant Tween-20 on the background medium, scattering effects and combination of scattering and absorption within a luminescent body on PpIX. The results indicated that the intrinsic emission peaks are red shifted by the scattering particles or surfactant, whilst the scattering agent and the absorbent can alter the emission intensity substantially. We corroborated that phantoms containing higher surfactant content (>0.5% Tween 20) are essential to prepare stable aqueous phantoms.

scholarly journals Assembly of a G-Quadruplex Repair Complex by the FANCJ DNA Helicase and the REV1 Polymerase

Genes ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 5
Author(s):  
Kaitlin Lowran ◽  
Laura Campbell ◽  
Phillip Popp ◽  
Colin G. Wu
Keyword(s):  
Dna Replication ◽  
Fluorescence Spectroscopy ◽  
Dna Helicase ◽  
Human Cells ◽  
Loop Length ◽  
Interacting Protein ◽  
Biolayer Interferometry ◽  
G4 Dna ◽  
G Quadruplex ◽  
The Impact

The FANCJ helicase unfolds G-quadruplexes (G4s) in human cells to support DNA replication. This action is coupled to the recruitment of REV1 polymerase to synthesize DNA across from a guanine template. The precise mechanisms of these reactions remain unclear. While FANCJ binds to G4s with an AKKQ motif, it is not known whether this site recognizes damaged G4 structures. FANCJ also has a PIP-like (PCNA Interacting Protein) region that may recruit REV1 to G4s either directly or through interactions mediated by PCNA protein. In this work, we measured the affinities of a FANCJ AKKQ peptide for G4s formed by (TTAGGG)4 and (GGGT)4 using fluorescence spectroscopy and biolayer interferometry (BLI). The effects of 8-oxoguanine (8oxoG) on these interactions were tested at different positions. BLI assays were then performed with a FANCJ PIP to examine its recruitment of REV1 and PCNA. FANCJ AKKQ bound tightly to a TTA loop and was sequestered away from the 8oxoG. Reducing the loop length between guanine tetrads increased the affinity of the peptide for 8oxoG4s. FANCJ PIP targeted both REV1 and PCNA but favored interactions with the REV1 polymerase. The impact of these results on the remodeling of damaged G4 DNA is discussed herein.

Formation of Lunar Craters and Bright Rays as a Result of Meteorite Impacts

1962 ◽  
Vol 14 ◽  
pp. 415-418
Author(s):  
K. P. Stanyukovich ◽  
V. A. Bronshten
Keyword(s):  
Explosive Charge ◽  
The Moon ◽  
Meteorite Impacts ◽  
The Earth ◽  
Lunar Craters ◽  
The Impact

The phenomena accompanying the impact of large meteorites on the surface of the Moon or of the Earth can be examined on the basis of the theory of explosive phenomena if we assume that, instead of an exploding meteorite moving inside the rock, we have an explosive charge (equivalent in energy), situated at a certain distance under the surface.

The Geosciences Applied to Lunar Exploration

1962 ◽  
Vol 14 ◽  
pp. 169-257 ◽  
Author(s):  
J. Green
Keyword(s):  
Lunar Surface ◽  
Probable Mechanism ◽  
Point Of View ◽  
Lunar Exploration ◽  
Geological Model ◽  
Apply Geophysics ◽  
Surface Features ◽  
The Impact

The term geo-sciences has been used here to include the disciplines geology, geophysics and geochemistry. However, in order to apply geophysics and geochemistry effectively one must begin with a geological model. Therefore, the science of geology should be used as the basis for lunar exploration. From an astronomical point of view, a lunar terrain heavily impacted with meteors appears the more reasonable; although from a geological standpoint, volcanism seems the more probable mechanism. A surface liberally marked with volcanic features has been advocated by such geologists as Bülow, Dana, Suess, von Wolff, Shaler, Spurr, and Kuno. In this paper, both the impact and volcanic hypotheses are considered in the application of the geo-sciences to manned lunar exploration. However, more emphasis is placed on the volcanic, or more correctly the defluidization, hypothesis to account for lunar surface features.

Asteroid and Comet Impact Speeds upon Mars: Significance for Panspermia and the Supply of Organics

1997 ◽  
Vol 161 ◽  
pp. 197-201 ◽  
Author(s):  
Duncan Steel
Keyword(s):  
Probability Distributions ◽  
Regions Of Interest ◽  
Significant Fraction ◽  
Organic Chemicals ◽  
Impact Speed ◽  
The Mean ◽  
The Impact

AbstractWhilst lithopanspermia depends upon massive impacts occurring at a speed above some limit, the intact delivery of organic chemicals or other volatiles to a planet requires the impact speed to be below some other limit such that a significant fraction of that material escapes destruction. Thus the two opposite ends of the impact speed distributions are the regions of interest in the bioastronomical context, whereas much modelling work on impacts delivers, or makes use of, only the mean speed. Here the probability distributions of impact speeds upon Mars are calculated for (i) the orbital distribution of known asteroids; and (ii) the expected distribution of near-parabolic cometary orbits. It is found that cometary impacts are far more likely to eject rocks from Mars (over 99 percent of the cometary impacts are at speeds above 20 km/sec, but at most 5 percent of the asteroidal impacts); paradoxically, the objects impacting at speeds low enough to make organic/volatile survival possible (the asteroids) are those which are depleted in such species.

Organic Syntheses During the Impact of a Comet with a Gaseous Planet

1997 ◽  
Vol 161 ◽  
pp. 189-195
Author(s):  
Cesare Guaita ◽  
Roberto Crippa ◽  
Federico Manzini
Keyword(s):  
Polymeric Material ◽  
Molecular Form ◽  
Parent Compound ◽  
Blue Filter ◽  
Organic Syntheses ◽  
The Impact

AbstractA large amount of CO has been detected above many SL9/Jupiter impacts. This gas was never detected before the collision. So, in our opinion, CO was released from a parent compound during the collision. We identify this compound as POM (polyoxymethylene), a formaldehyde (HCHO) polymer that, when suddenly heated, reformes monomeric HCHO. At temperatures higher than 1200°K HCHO cannot exist in molecular form and the most probable result of its decomposition is the formation of CO. At lower temperatures, HCHO can react with NH3 and/or HCN to form high UV-absorbing polymeric material. In our opinion, this kind of material has also to be taken in to account to explain the complex evolution of some SL9 impacts that we observed in CCD images taken with a blue filter.

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