scholarly journals Photophysical Detection of Singlet Oxygen

2021 ◽  
Author(s):  
Arnab Maity
Keyword(s):  
Singlet Oxygen ◽  
Indirect Method ◽  
Chemical Reactivity ◽  
Direct Method ◽  
Therapeutic Process ◽  
Fluorescence Emission ◽  
Electronically Excited ◽  
Detection Probe ◽  
Current Research Interest

The chemical reactivity of singlet oxygen (1O2) (SO) derives from its electronically excited state. Being a unique reactive oxygen species SO takes part in many important atmospheric, biological physical, chemical, and therapeutic process and attracted current research interest. To understand the mechanistic pathways in various process the detection and quantification of SO is very important. The direct method of detection is very challenging due to its highly reactive nature. Only direct method of determination of phosphorescence of SO at 1270 nm has been utilised but that also puts some limitation due to very low luminescence quantum yield. Indirect method using UV–Vis spectrophotometric, fluorescent and chemiluminescent probes has been extensively studied for this purpose. Elucidation of various mechanistic processes improvised the use of sophisticated spectroscopic detection probe for SO have been discussed in a simple and lucid manner in this article through citation of literature examples. Four major spectroscopic methods i.e. spectrophotometry, fluorescence, emission and chemiluminescence are elaborately discussed with special emphasis to chemical probes having high selectivity and sensitivity for SO.

scholarly journals The determination of the heat of dissociation of fluorine and of the latent heat of vaporisation of lithium

1932 ◽  
Vol 136 (829) ◽  
pp. 76-82 ◽  
Keyword(s):  
High Temperature ◽  
Absorption Spectra ◽  
Latent Heat ◽  
Chemical Reactivity ◽  
Direct Method ◽  
Thermal Methods ◽  
Heat Of Dissociation

The heats of dissociation of chlorine, bromine, and iodine have been determined by thermal methods and estimated to be 58·9, 45·2 and 35·2 kilo-cals. respectively. But no data are yet known concerning the heat of dissociation of fluorine. It is very difficult to subject fluorine to the same treatment as Cl 2 , Br 2 and I 2 ( i. e ., heating to a high temperature in a sealed quartz bulb) owing to its extreme chemical reactivity, and hence no direct method of determining the heat of dissociation of fluorine has yet been devised. In the present paper I have determined it indirectly by interpretation of the absorption spectra of alkali fluorides (for the present only NaF and KF). A short theory of the experiment is given below.

Präzise Messung der γ-Absolutintensität niederenergetischer Übergänge bei (n, γ)-Reaktionen und beim radioaktiven Zerfall mit einem Kristallspektrometer

1966 ◽  
Vol 21 (9) ◽  
pp. 1328-1343 ◽  
Author(s):  
Horst A. Neumann
Keyword(s):  
Neutron Capture ◽  
Indirect Method ◽  
Research Reactor ◽  
Direct Method ◽  
Capture Rate ◽  
Radioactive Decay ◽  
Low Energy ◽  
Crystal Spectrometer ◽  
Γ Rays

A direct and an indirect method for accurate measurement of absolute intensities of low-energy γ-rays from neutron capture and radioactive decay by means of a crystal spectrometer is described. The 478-keV peak of Li7 (target B10) is used in the direct method while the 412-keV peak of Hg198 (target Au) is used in the indirect method. In addition the intensity calibration of the crystal spectrometer used in FRM (Munich Research Reactor), determination of the neutron capture rate and corrections for γ and neutron self-absorption are discussed in some detail. Absolute γ-intensities per neutron capture or decay respectively were determined for a number of strong low energy γ transitions in Rh104, Cd114, Sm150, Sm153, Eu152, Eu153, Eu154, Gd156, Gd158, Dy162, Dy163, Dy164, Dy165, Ho165, Ho166 and Er166. An accuracy of 2% was obtained in the most favorable cases.

A Study of the metabolism of fowls: I. A calorimeter for the direct determination of the metabolism of fowls

1939 ◽  
Vol 29 (3) ◽  
pp. 431-451 ◽  
Author(s):  
Thomas Deighton
Keyword(s):  
Heat Capacity ◽  
Indirect Method ◽  
Direct Method ◽  
Direct Determination ◽  
Heat Evolution ◽  
Point Of View ◽  
Heat Output ◽  
Human Being ◽  
Margin Of Strength

Some years ago my colleague, Mr E. T. Halnan, suggested the construction of the present instrument for the purpose of determining figures for domestic fowls corresponding to those of Kellner for ruminants.Owing to the activity of the fowl, it is essential that an instrument for this purpose should be capable of recording accurately a heat output which may be varying with some rapidity.From this point of view the advantages of the indirect method were considered but were eventually rejected for the following reasons: (a) the advantage accruing from our greater experience of the direct method in this laboratory, (b) the work of Adams & Poulton (1933, 1934, 1935) calling in question the fundamental bases of the indirect method, and (c) the very variable R.Q.'S obtained in earlier work by numerous investigators working with birds.That the decision was wise soon became apparent when work on birds was begun. It is certain that no ordinary apparatus of that kind could possibly take account of the variations caused by the constant changes in activity.The principle of a “compensatory” or “balanced” calorimeter more or less as developed by Noyons (1927), Benedict (1927) and Heyster (1933), was selected as the most likely to give promptness in registration, and this choice has been amply justified in the result. Such instruments can be very lightly constructed, although where living animals are concerned, since their movements cannot be controlled, as can those of a human being, a greater margin of strength has to be provided, which naturally increases the heat capacity and lag and reduces sensitivity to small changes in heat evolution.

Determination of the Speed of an Unmanned Rescue Vehicle

2015 ◽  
Vol 220-221 ◽  
pp. 940-945 ◽  
Author(s):  
Andrzej Zbrowski ◽  
Wojciech Jóźwik
Keyword(s):  
Rotational Speed ◽  
Indirect Method ◽  
Direct Method ◽  
Indirect Measurement ◽  
Measurement Range ◽  
Test System ◽  
Correct Operation ◽  
Linear Speed ◽  
A Direct Method

The article presents the process of determining the speed of an unmanned rescue vehicle.The conducted investigations involved a measurement system developed for testing dynamic lorries. The application of a test system for low-speed all-terrain vehicles was possible due to a wide measurement range of sensors. Speed was tested employing two following methods:an indirect method consisting of the measurement of the instantaneous rotational speed of the wheel;a direct method consisting of the measurement of speed against the ground, taken with an optical speed sensor.The authors also describe the sources of interferences characteristic of both methods that include:the wheelspin affecting the correctness of speed determination in the indirect measurement;the unevenness of the surface (ground) hindering the correct operation of the optical speed sensor.The paper also presents the characteristics of the rotational speed of the wheels obtained in road and off-road conditions. Based on the obtained signals, linear speed was determined. Additionally, the article discusses methods for eliminating measurement disturbances.

scholarly journals Turbidimetry as an alternative method to determine the rating curve of suspended sediments

2011 ◽  
Vol 31 (3) ◽  
pp. 598-606 ◽  
Author(s):  
Kayla Poletto ◽  
Silvio C. Sampaio ◽  
Manoel M. F. de Queiroz ◽  
Benedito M. Gomes ◽  
Rosimaldo Soncela
Keyword(s):  
Indirect Method ◽  
Direct Method ◽  
Suspended Sediments ◽  
Left Bank ◽  
Alternative Procedure ◽  
Rating Curve ◽  
The West ◽  
Function Type ◽  
Indirect Determination

Understanding hydrosedimental behavior of a watershed is essential for properly managing and using its hydric resources. The objective of this study was to verify the feasibility of the alternative procedure for the indirect determination of the sediment key curve using a turbidimeter. The research was carried out on the São Francisco Falso River, which is situated in the west of the state of Paraná on the left bank of ITAIPU reservoir. The direct method was applied using a DH-48 sediment suspended sampler. The indirect method consisted of the use of a linigraph and a turbidimeter. Based on the results obtained, it was concluded that the indirect method using a turbidimeter showed to be fully feasible, since it gave a power function-type mathematical model equal of the direct method. Furthermore, the average suspended sediment discharge into the São Francisco Falso River during the 2006/2007 harvest was calculated at 7.26 metric t day-1.

Indirect Method for Determination of Insoluble Solids in Processed Vegetable Products

1973 ◽  
Vol 56 (6) ◽  
pp. 1508-1508
Author(s):  
Dov Basker
Keyword(s):  
Filter Paper ◽  
Indirect Method ◽  
Direct Method ◽  
Vegetable Products ◽  
Good Agreement

Abstract An indirect method for determining insoluble solids in processed vegetable products has been developed which avoids the problem of clogged filter paper that occurs in the direct method. Good agreement was obtained when apricots and onions were analyzed by the 2 methods.

Ab initio structure determination of cytochrome c6 by combined reciprocal space-real space approach

2003 ◽  
Vol 218 (1) ◽  
Author(s):  
K. Chowdhury ◽  
S. Ghosh ◽  
M. Mukherjee
Keyword(s):  
Cytochrome C ◽  
Ab Initio ◽  
Structure Determination ◽  
Direct Method ◽  
Real Space ◽  
Reciprocal Space ◽  
Cytochrome C6 ◽  
Ab Initio Structure ◽  
Space Approach

AbstractThe direct method program SAYTAN has been applied successfully to redetermine the structure of cytochrome c

scholarly journals Photophysical Properties of Protoporphyrin IX, Pyropheophorbide-a, and Photofrin® in Different Conditions

2021 ◽  
Vol 14 (2) ◽  
pp. 138
Author(s):  
Bauyrzhan Myrzakhmetov ◽  
Philippe Arnoux ◽  
Serge Mordon ◽  
Samir Acherar ◽  
Irina Tsoy ◽  
...  
Keyword(s):  
Singlet Oxygen ◽  
Photophysical Properties ◽  
Protoporphyrin Ix ◽  
Fluorescence Emission ◽  
Solvent Polarity ◽  
Visible Absorption ◽  
Light Dosimetry ◽  
Time Resolved ◽  
Pyropheophorbide A ◽  
Influence Of Solvent

Photodynamic therapy (PDT) is an innovative treatment of malignant or diseased tissues. The effectiveness of PDT depends on light dosimetry, oxygen availability, and properties of the photosensitizer (PS). Depending on the medium, photophysical properties of the PS can change leading to increase or decrease in fluorescence emission and formation of reactive oxygen species (ROS) especially singlet oxygen (1O2). In this study, the influence of solvent polarity, viscosity, concentration, temperature, and pH medium on the photophysical properties of protoporphyrin IX, pyropheophorbide-a, and Photofrin® were investigated by UV-visible absorption, fluorescence emission, singlet oxygen emission, and time-resolved fluorescence spectroscopies.

UV-Vis Spectrophotometrical and Analytical Methodology for the Determination of Singlet Oxygen in New Antibacterials Drugs

2007 ◽  
Vol 2 ◽  
pp. 117739010700200 ◽  
Author(s):  
Tamara Zoltan ◽  
Franklin Vargas ◽  
Carla Izzo
Keyword(s):  
Reactive Oxygen Species ◽  
Singlet Oxygen ◽  
Nalidixic Acid ◽  
Reactive Oxygen ◽  
Oxygen Species ◽  
Inexpensive Method ◽  
Analytical Methodology ◽  
First Time

We have determined and quantified spectrophotometrically the capacity of producing reactive oxygen species (ROS) as 1O2 during the photolysis with UV-A light of 5 new synthesized naphthyl ester derivates of well-known quinolone antibacterials (nalidixic acid (1), cinoxacin (2), norfloxacin (3), ciprofloxacin (4) and enoxacin (5)). The ability of the naphthyl ester derivatives (6-10) to generate singlet oxygen were detecting and for the first time quantified by the histidine assay, a sensitive, fast and inexpensive method. The following tendency of generation of singlet oxygen was observed: compounds 7 >10 > 6 > 8 > 9 >> parent drugs 1-5.

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