scholarly journals Jean-Louis Luche and the Interpretation of Sonochemical Reaction Mechanisms

Molecules ◽  
2021 ◽  
Vol 26 (3) ◽  
pp. 755
Author(s):  
Mircea Vinatoru ◽  
Timothy J. Mason
Keyword(s):  
Free Radical ◽  
Ultrasonic Irradiation ◽  
Reaction Mechanisms ◽  
Acoustic Cavitation ◽  
Early Years ◽  
Sound Energy ◽  
Mechanical Effects ◽  
Sonochemical Reaction ◽  
Young Branch ◽  
The Difference

Sonochemistry can be broadly defined as the science of chemical and physical transformations produced under the influence of sound. The use of sound energy is rather a young branch of chemistry and does not have the clear definitive rules of other, more established, divisions such as those in cycloaddition reactions or photochemistry. Nevertheless, there are a few guidelines which can help to predict what is going to happen when a reaction mixture is submitted to ultrasonic irradiation. Jean-Louis Luche, formulated some ideas of the mechanistic pathways involved in sonochemistry more than 30 years ago. He introduced the idea of “true” and “false” sonochemical reactions both of which are the result of acoustic cavitation. The difference was that the former involved a free radical component whereas only mechanical effects played a role the latter. The authors of this paper were scientific collaborators and friends of Jean-Louis Luche during those early years and had the chance to discuss and work with him on the mechanisms of sonochemistry. In this paper we will review the original rules (laws) as predicted by Jean-Louis Luche and how they have been further developed and extended in recent years.

Effect of ring substituents on the fluorescence spectra of substituted diarylcarbenes

1988 ◽  
Vol 66 (3) ◽  
pp. 491-494 ◽  
Author(s):  
J. C. Scaiano ◽  
D. Weir
Keyword(s):  
Free Radical ◽  
Temperature Dependence ◽  
Fluorescence Spectra ◽  
Excellent Correlation ◽  
Emission Data ◽  
The Difference

The fluorescence spectra of a series of ring-substituted diarylcarbenes have been examined. The solution spectra are generally red shifted by 25–30 nm with respect to the band positions in matrices at 77 K. The difference is believed to reflect emission from non-relaxed conformations at 77 K. Both electron-withdrawing and -donating substituents lead to red shifts in the emission. These shifts are essentially additive, and the carbene emission data show an excellent correlation with free radical fluorescence data for the corresponding diarylmethyl radicals. The temperature dependence of excited carbene lifetimes have been examined for a few representative examples.

Pure and Applied Research in Linguistics: Is the Difference Merely One of Motivation?

1979 ◽  
Vol 1 (2) ◽  
pp. 77-90 ◽  
Author(s):  
S.P. Corder
Keyword(s):  
Personal Identity ◽  
Applied Research ◽  
Applied Linguistics ◽  
Early Years ◽  
Academic World ◽  
The Social ◽  
Learned Societies ◽  
The Difference ◽  
Own Name ◽  
Do So

It is perhaps natural that in the early years of emergence of a new field of study and research its practitioners should from time to time ask themselves what is the nature of the activity they are engaged in. The need to do so may stem from a number of different causes: philosophical, sociological and psychological. The practitioners may feel the need to establish a personal identity, that is, some accepted place for themselves in the social structure of the academic world, to achieve respect and recognition as workers in the field of scholarship, a role in the institution of higher studies. They may feel that the discipline they profess is not properly recognised within the scholarly domain, its place not clearly determined in the structure of science or scholarship, its value to society not appreciated; and that consequently it does not attract research funds in its own name, permit the establishment of courses and programmes which lead to academic degrees or qualifications bearing its name, or of learned societies devoted to discussing its problems and disseminating its notions. All of these factors I believe play a part in the motivations for the constantly renewed discussion of WHAT IS APPLIED LINGUISTICS? None of them is in any way reprehensible or unworthy. The intensity or frequency with which these discussions occur is a response to the prevailing orthodox views about the discipline itself and its relation to neighbouring disciplines found in the society where the discussions take place, and to the degree to which its practitioners (i.e. people who call themselves applied linguists) feel oppressed, unrecognised or undervalued by the members of the institution in which they work and with whom they interact. This is a whole field of investigation open to the sociologist of science to describe and explain.

scholarly journals Gasification Pathways and Reaction Mechanisms of Primary Alcohols in Supercritical Water

2019 ◽  
Author(s):  
Brian Pinkard ◽  
John Kramlich ◽  
Igor V. Novosselov
Keyword(s):  
Free Radical ◽  
Supercritical Water ◽  
Reaction Mechanisms ◽  
Radical Reaction ◽  
Water Environment ◽  
Waste To Energy ◽  
Reaction Pathways ◽  
Free Radical Reaction ◽  
Reaction Products ◽  
Primary Alcohols

<div> <p></p><p>Supercritical water gasification is a promising waste-to-energy technology with the ability to convert aqueous and/or heterogeneous organic feedstocks to high-value gaseous products. Reaction behavior of complex molecules in supercritical water can be inferred through knowledge of the reaction pathways of model compounds in supercritical water. In this study methanol, ethanol, and isopropyl alcohol are gasified in a continuous supercritical water reactor at temperatures between 500 and 560 °C, and for residence times between 3 and 8 s. <i>In situ</i> Raman spectroscopy is used to rapidly identify and quantify reaction products. The results suggest the dominance of chain-branching, free radical reaction mechanisms that are responsible for decomposing primary alcohols in the supercritical water environment. The presence of a catalytic surface is proposed to be highly significant for initiating radical reactions. Global reaction pathways are proposed, and mechanisms for free radical reaction initiation, propagation, and termination are discussed in light of these and previously published experimental results.</p><br><p></p></div>

scholarly journals Gasification Pathways and Reaction Mechanisms of Primary Alcohols in Supercritical Water

2019 ◽  
Author(s):  
Brian Pinkard ◽  
John Kramlich ◽  
Igor V. Novosselov
Keyword(s):  
Free Radical ◽  
Supercritical Water ◽  
Reaction Mechanisms ◽  
Radical Reaction ◽  
Water Environment ◽  
Waste To Energy ◽  
Reaction Pathways ◽  
Free Radical Reaction ◽  
Reaction Products ◽  
Primary Alcohols

<div> <p></p><p>Supercritical water gasification is a promising waste-to-energy technology with the ability to convert aqueous and/or heterogeneous organic feedstocks to high-value gaseous products. Reaction behavior of complex molecules in supercritical water can be inferred through knowledge of the reaction pathways of model compounds in supercritical water. In this study methanol, ethanol, and isopropyl alcohol are gasified in a continuous supercritical water reactor at temperatures between 500 and 560 °C, and for residence times between 3 and 8 s. <i>In situ</i> Raman spectroscopy is used to rapidly identify and quantify reaction products. The results suggest the dominance of chain-branching, free radical reaction mechanisms that are responsible for decomposing primary alcohols in the supercritical water environment. The presence of a catalytic surface is proposed to be highly significant for initiating radical reactions. Global reaction pathways are proposed, and mechanisms for free radical reaction initiation, propagation, and termination are discussed in light of these and previously published experimental results.</p><br><p></p></div>

PERBANDINGAN METODE EKSTRAKSI MASERASI DAN SOKLETASI TERHADAP AKTIVITAS ANTIOKSIDAN EKSTRAK ETANOL DAUN JAMBU BOL (Syzygium malaccense L.)

2017 ◽  
Vol 3 (1) ◽  
pp. 91
Author(s):  
Henny Nurhasnawati ◽  
Sukarmi Sukarmi ◽  
Fitri Handayani
Keyword(s):  
Antioxidant Activity ◽  
Free Radical ◽  
Vitamin C ◽  
Extraction Methods ◽  
Natural Antioxidant ◽  
Comparison Of Methods ◽  
Activity Test ◽  
Ic50 Value ◽  
The Difference ◽  
Free Radical Activity

Malay apple (Syzygium malaccense L.) is a plant that can be used for treatment. Antioxidants have the activity to reduce free radical compounds which is one of the causes of the emergence of various diseases in humans. The purpose of this study to determine the comparison of methods of maceration and socletation extraction of antioxidant activity of malay apple leaf. Research stages include sampling, plant determination, making of simplisia, maceration extraction and socletation with 70% ethanol solvent and determine the antioxidant activity by UV-Vis spectrophotometry with DPPH (1,1-diphenyl-2-picrylhydrazyl) as free radical. The parameter is IC50 value that is the concentration of antioxidant compound which can cause 50% loss of DPPH free radical activity. Although both methods show very strong antioxidant activity, it can be concluded that the difference in extraction methods has an effect on the antioxidant activity produced. The results of antioxidant activity test showed that socletation methods gave an average IC50 value of 37.67 ppm, this value is higher than maceration methods with an average IC50 value of 47.80 ppm. Malay apple leaf has the potential as a natural antioxidant, although it has a lower IC50 value than vitamin C which is 9.72 ppm.

Entrepreneurial and Vocational Education and Training

2004 ◽  
Vol 18 (1) ◽  
pp. 53-61 ◽  
Author(s):  
Jay Mitra ◽  
Harry Matlay
Keyword(s):  
Small Business ◽  
Central Europe ◽  
Small Businesses ◽  
Western Europe ◽  
Longitudinal Research ◽  
Early Years ◽  
Vocational Education And Training ◽  
New Thinking ◽  
The Difference ◽  
The Uk

The social, economic and political systems of former communist countries have faced considerable changes since the late 1980s. Most countries in Eastern and Central Europe have undergone their own individual brand of transition from a centrally planned, command system to a more or less liberalized, Western-style market economy Many observers agree that in general there is still a great deal to be done to achieve the key goal of economic liberalization, but there is little agreement among academics as to what would constitute an effective and stabilizing transition in the region. In common with contemporary Western beliefs and attitudes, much of the new thinking and hopes for economic regeneration in Eastern and Central Europe have centred on entrepreneurship and small business development. In the early years of transition, the influx of international aid became a stumbling block to the establishment of the kind of support systems that had proved crucial for the survival and growth of small businesses in Western Europe. The demand for entrepreneurial skills and the deficiencies inherent in their new labour markets exposed post-communist economies to external shocks such as those caused by the termination of COMECON agreements and the Gulf War. The longitudinal research on which this paper is based was closely modelled on ongoing work by the authors, which involves an in-depth investigation of the ‘paradox of training’, the difference between attitude and practice, that exists in the small business sector of the UK economy. Following the results of a pilot study undertaken in the UK, the research was extended to include small business sectors across Eastern, Central and Western Europe.

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