Studies of free radical-mediated cryoinjury in the unicellular green algaEuglena gracilisusing a non-destructive hydroxyl radical assay: A novel approach for developing protistan cryopreservation strategies

2000 ◽  
Vol 32 (2) ◽  
pp. 157-170 ◽  
Author(s):  
Roland A. Fleck ◽  
Erica E. Benson ◽  
David H. Bremner ◽  
John G. Day
Keyword(s):  
Free Radical ◽  
Hydroxyl Radical ◽  
Novel Approach ◽  
Non Destructive

scholarly journals A New Prototype for Automatic Identification of Stone Block Internal Structure

2021 ◽  
Vol 11 (14) ◽  
pp. 6630
Author(s):  
Bernardo Anes ◽  
Joao Figueiredo ◽  
Mouhaydine Tlemçani
Keyword(s):  
Internal Structure ◽  
Empirical Method ◽  
Automatic Process ◽  
Automatic Identification ◽  
Ultrasonic Tomography ◽  
Stone Block ◽  
Novel Approach ◽  
Process Measurements ◽  
Automatic Positioning ◽  
Non Destructive

Nowadays, the inner shape and economic viability of a stone block is dependent on the skill and experience of the “expert” that makes predictions based on external observations. This actual procedure is an extremely high empirical method, and when it fails, substantial work, time, and money is wasted. At present, researchers are committed to developing models to predict the stone block internal structure based on non-destructive tests. Ultrasonic tomography and electrical resistivity tomography are the tests that best fit these objectives. Trying to improve the existing procedures for collecting stone information and data exporting, a novel approach to perform both tomographies is proposed in this paper. This novel approach presents sound advantages regarding the current manual procedure: namely, (i) high accuracy due to a new automatic positioning system; (ii) no need for highly skilled operators to process measurements; (iii) measurements are much easier to derive, and results are quickly delivered. A comparison between the new automatic process and the current manual procedure shows that the manual procedure has a very low accuracy when compared to the new developed automatic system. The automatic measurements show extremely significant time savings, which is a relevant issue for the future competitiveness of the stone sector.

Evaluation of antioxidant activity of Melothria maderaspatana in vitro

2010 ◽  
Vol 5 (2) ◽  
pp. 224-230 ◽  
Author(s):  
Boobalan Raja ◽  
Kodukkur Pugalendi
Keyword(s):  
Hydrogen Peroxide ◽  
Antioxidant Activity ◽  
Free Radical ◽  
Hydroxyl Radical ◽  
Superoxide Anion ◽  
Radical Scavenging ◽  
Reducing Power ◽  
Free Radical Scavenging ◽  
Melothria Maderaspatana

AbstractIn this study, an aqueous extract of leaves from Melothria maderaspatana was tested for in vitro antioxidant activity. Free radical scavenging assays, such as hydroxyl radical, hydrogen peroxide, superoxide anion radical and 2,2-diphenyl-1-picryl hydrazyl (DPPH), 2,2’-azinobis-(3-ethyl-enzothiazoline-6-sulfonic acid) (ABTS) radical scavenging, and reducing power assay, were studied. The extract effectively scavenged hydroxyl radical, hydrogen peroxide and superoxide anion radicals. It also scavenged DPPH and ABTS radicals. Furthermore, it was found to have reducing power. All concentrations of leaf extract exhibited free radical scavenging and antioxidant power, and the preventive effects were in a dose-dependent manner. The antioxidant activities of the above were compared to standard antioxidants such as butylated hydroxytoluene (BHT), ascorbic acid, and α-tocopherol. The results obtained in the present study indicate that the M. maderaspatana extract could be considered a potential source of natural antioxidant.

Evaluating the Effect of Termination by Chain - Chain Coupling in Living Free-Radical Polymerizations

2003 ◽  
Vol 56 (8) ◽  
pp. 775 ◽  
Author(s):  
Jeffrey Pyun ◽  
Ian Rees ◽  
Jean M. J. Fréchet ◽  
Craig J. Hawker
Keyword(s):  
Free Radical ◽  
Star Polymers ◽  
Star Polymer ◽  
Direct Result ◽  
Vinyl Monomers ◽  
Linear Polymers ◽  
Radical Coupling ◽  
Novel Approach ◽  
Vis Spectroscopy ◽  
Radical Polymerizations

A novel approach based on the reaction of multifunctional star polymers with chromophore-labelled linear polymers is presented for evaluating the extent of termination by chain–chain coupling during living free-radical polymerizations. A mixed initiating system consisting of an unlabelled, multifunctional initiator and an excess of a monofunctional alkoxyamine initiator containing a chromophore, such as pyrene, is used to initiate the living polymerization of vinyl monomers leading to a mixture of star and linear polymers. The occurrence of chain–chain coupling is readily identified and quantified by isolating the star polymer that is obtained and elucidating the level of incorporation of pyrene units by UV/vis spectroscopy. This allows the level of chain–chain coupling to be determined since the inclusion of pyrene into the star structure is a direct result of termination by radical coupling.

MODELING A THERMAL IMAGING PROCESS IN AN IMPACT DAMAGED COMPOSITE STRUCTURE

2005 ◽  
Vol 02 (01) ◽  
pp. 63-76
Author(s):  
M. Z. ISKANDARANI ◽  
N. F. SHILBAYEH
Keyword(s):  
Data Analysis ◽  
Composite Structure ◽  
Thermal Imaging ◽  
Electronic Circuit ◽  
Impact Damage ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Novel Approach ◽  
Wavelength Variation ◽  
Non Destructive

An innovative NDT (non-destructive testing) technique for interrogating materials for their defects has been developed successfully. The technique has a novel approach to data analysis by employing intensity, RGB signal re-mix and wavelength variation of a thermally generated IR-beam onto the specimen under test which can be sensed and displayed on a computer screen as an image. Specimen inspection and data analysis are carried out through pixel level re-ordering and shelving techniques within a transformed image file using a sequence grouping and regrouping software system, which is specifically developed for this work. The interaction between an impact damaged RIM composite structure and thermal energy is recorded, analyzed, and modeled using an equivalent Electronic circuit. Effect of impact damage on the integrity of the composite structure is also discussed.

scholarly journals Ca2+-dependent K+ channels and Na+-K+-ATPase mediate H2O2- and superoxide-induced relaxations in canine trachealis

2000 ◽  
Vol 88 (2) ◽  
pp. 745-752 ◽  
Author(s):  
Luke J. Janssen ◽  
Stuart J. Netherton ◽  
Denise K. Walters
Keyword(s):  
Free Radical ◽  
Hydroxyl Radical ◽  
Xanthine Oxidase ◽  
Radical Scavenger ◽  
Membrane Hyperpolarization ◽  
K Channels ◽  
Hydroxyl Radical Scavenger ◽  
Ionic Mechanisms ◽  
Resting Tone

We examined the ionic mechanisms underlying the responses of canine trachealis to superoxide (generated in vitro by using xanthine oxidase or added exogenously) and peroxide (generated spontaneously in vitro by the dismutation of superoxide or added exogenously). Although neither had any effect on resting tone, both triggered relaxations in carbachol-precontracted tissues. These relaxations were eliminated by catalase but were much less sensitive to the hydroxyl radical scavenger dimethylthiourea, indicating they were mediated primarily by peroxide. These relaxations were decreased in magnitude and/or slowed by nifedipine (10− 6 M), ouabain (10− 6 M), or tetraethylammonium (25 mM), but not by 4-aminopyridine (5 mM), and were small or absent in tissues precontracted with 30 mM KCl. Finally, peroxide triggered membrane hyperpolarization and elevated cytosolic concentration of Ca2+ (primarily via release from the internal store). Thus peroxide-mediated relaxations seem to involve Ca2+ release, opening of Ca2+-dependent K+ channels, hyperpolarization, closure of Ca2+ channels, and relaxation. In addition, some other free radical (hydroxyl radical?) may activate the Na+-K+ pump, also hyperpolarizing the membrane and causing relaxation.

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