Solvatochromic effects in absorption and luminescence spectra and stability of emission quantum yield of carbon nanoparticles (part I)

2021 ◽  
Vol 7 ◽  
pp. 5-24
Author(s):  
S. A. Kazaryan ◽  
◽  
V. N. Nevolin ◽  
S. Kh. Pilosyan ◽  
◽  
...  
Keyword(s):  
Quantum Yield ◽  
Carbon Nanoparticles ◽  
Significant Contribution ◽  
Luminescence Spectra ◽  
Specific Interactions ◽  
Fundamental Properties ◽  
Wide Range ◽  
Absorption And Luminescence Spectra ◽  
Emission Quantum Yield

The features of the solvatochromic effects of absorption (Ab) and photoluminescence (PL) spectra, as well as the quantum yield of emission (QYE) of carbon nanoparticles (CNPs) synthesized by various methods from a mixture of citric acid and nitrogen-containing precursors, in protic and aprotic solvents have been studied. It has been shown that the parameters of the spectra Ab, PL and the QYE value of particle solutions to a large extent depend on the method, conditions and modes of synthesis, the method of modification and separation of CNPs, the types and composition of precursors, and also the fundamental properties and pH of solvents. In solvents with a dielectric constant of 4.5 – 109.5, the QYE value of particles varies in a wide range from 10.8 to 100.0 %, and the PL band peak shifts from 466.4 to 536.8 nm. The presence of strong solvatochromic effects in the spectra of Ab and PL particles was shown, and the important role of the processes of protonation and deprotonation of surface groups of CNPs was established. The influence of universal and specific interactions on the spectroscopic parameters of CNPs has been investigated, and a significant contribution to the solvatochromic effects of specific interactions has been demonstrated.

scholarly journals Influence of PDA Coating on the Structural, Optical and Surface Properties of ZnO Nanostructures

Nanomaterials ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2438 ◽  
Author(s):  
Daina Damberga ◽  
Viktoriia Fedorenko ◽  
Kārlis Grundšteins ◽  
Şahin Altundal ◽  
Andris Šutka ◽  
...  
Keyword(s):  
Optical Properties ◽  
Surface Properties ◽  
Optical Sensors ◽  
Zno Nanostructures ◽  
Sensor Applications ◽  
Fundamental Properties ◽  
Model Molecule ◽  
Wide Range ◽  
Pl Quenching

Polydopamine (PDA) is a new biocompatible material, which has prospects in biomedical and sensor applications. Due to functional groups, it can host wide range of biomolecules. ZnO nanostructures are well known templates for optical sensors and biosensors. The combination of ZnO and PDA results in a change of optical properties of ZnO–PDA composites as a shift of photoluminescence (PL) peaks and PL quenching. However, to date, the effect of the PDA layer on fundamental properties of ZnO–PDA nanostructures has not been studied. The presented paper reports on optical and surface properties of novel ZnO–PDA nanocomposites. PDA layers were chemically synthesized on ZnO nanostructures from different solution concentrations of 0.3, 0.4, 0.5 and 0.7 mg/mL. Structure, electronic and optical properties were studied by SEM, Raman, FTIR, diffuse reflectance and photoluminescence methods. The Z-potential of the samples was evaluated in neutral pH (pH = 7.2). The response of the samples towards poly-l-lysine adsorption, as a model molecule, was studied by PL spectroscopy to evaluate the correlation between optical and surface properties. The role of the PDA concentration on fundamental properties was discussed.

Qualitative perspectives: through a methodological lens

2014 ◽  
Vol 11 (1) ◽  
pp. 13-28 ◽  
Author(s):  
Lee Parker
Keyword(s):  
Qualitative Research ◽  
Significant Contribution ◽  
Research Literature ◽  
Management Research ◽  
Content Type ◽  
Wide Range ◽  
Qualitative Methodologies ◽  
Insight Into ◽  
Management Scholarship

Purpose – This paper aims to offer an insight into the emergent qualitative methodological profile and its distinctive contribution to accounting and management scholarship, particularly reflecting upon the contribution of Qualitative Research in Accounting & Management (QRAM). Design/methodology/approach – It examines the range of qualitative methodologies employed in the research published across the ten years of QRAM and analyses the methodological discourse and its contribution to the armoury available to qualitative researchers. In association with these methodological developments, the paper offers a critique of the articulated role of theory in contemporary accounting and management qualitative research. Findings – A wide range of qualitative methodologies are found to be in evidence, with considerable scope for further adoption and development of some. Methodological exposition papers are found to be a significant contribution in the past decade and include methodological framework building, methodological applications, methodological critiques, and methodological development exemplars. Alongside methodology, the dual role of theory as either informing or reflecting methodology is presented. Originality/value – The paper provides a critical analysis and consideration of qualitative methodological literature development in the last ten years of accounting and management research literature, particularly reflected in QRAM. It identifies dominant methodologies in use, as well as opportunities for expanding the methodological menu in accounting and management research. Furthermore, it classifies groups of methodological papers and their contributing perspectives, as well as addressing the often-vexed relationship between theory and methodology.

Di-amidosils with tunable structure, morphology and emission quantum yield: the role of hydrogen bonding

2015 ◽  
Vol 3 (26) ◽  
pp. 6844-6861 ◽  
Author(s):  
S. C. Nunes ◽  
J. Hümmer ◽  
V. T. Freitas ◽  
R. A. S. Ferreira ◽  
L. D. Carlos ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Variable Structure ◽  
Photoluminescence Properties ◽  
Experimental Conditions ◽  
Yield Value ◽  
Structure Morphology ◽  
Tunable Structure ◽  
Degree Of Order ◽  
Emission Quantum Yield

Di-amidosil hybrids with variable structure, morphology and photoluminescence properties were obtained using different experimental conditions. A correlation between the emission quantum yield value and the degree of order of the amide–amide hydrogen-bonded array was established for mono- and di-amidosils.

scholarly journals Correction: Di-amidosils with tunable structure, morphology and emission quantum yield: the role of hydrogen bonding

2015 ◽  
Vol 3 (31) ◽  
pp. 8272-8272 ◽  
Author(s):  
S. C. Nunes ◽  
J. Hümmer ◽  
V. T. Freitas ◽  
R. A. S. Ferreira ◽  
L. D. Carlos ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Quantum Yield ◽  
Structure Morphology ◽  
Tunable Structure ◽  
Emission Quantum Yield

Correction for ‘Di-amidosils with tunable structure, morphology and emission quantum yield: the role of hydrogen bonding’ by S. C. Nunes et al., J. Mater. Chem. C, 2015, 3, 6844–6861.

scholarly journals DISCIPLES OF PASTEUR FROM RUSSIA

2019 ◽  
Vol 8 (4) ◽  
pp. 418-424
Author(s):  
M. M. Karapats ◽  
L. A. Kraeva
Keyword(s):  
Significant Contribution ◽  
Future Generations ◽  
Educational Institutions ◽  
Pasteur Institute ◽  
Petersburg Institute ◽  
Diagnostic Laboratory ◽  
Military Medical Academy ◽  
Medical Academy ◽  
Wide Range

Abstract. Outstanding scientist, microbiologist, chemist Louis Pasteur left a great legacy to future generations: many discoveries in the relevant fields of science, a large number of disciples, followers and the Paris Institute, bearing his name. Among Pasteur's disciples were more than a hundred Russian scientists, whose fate was different. Some of them returned Home and were able to make a significant contribution to the development of microbiology and immunology in Russia. Not all the names of Pasteur's disciples are known to a wide range of microbiologists. Therefore, the article presents brief materials about some more or less well known scientists-followers of Louis Pasteur. L.S. Tsenkovsky may be considered the founder of microbiology in Russia, who in 1882 published the book "Microorganisms", and later was able to independently create a vaccine against anthrax. Numerous trips to the Pasteur Institute in Paris had a positive value — Lev Semenovich was able to assess how to be equipped laboratories that deal with serious problems in the field of microbiology. Students of Pasteur L.L. Heydenreich, A.D. Pavlovsky, M.F. Popov, A.I. Sudakov, A.A. Raevsky was able not only to develop scientific areas in microbiology, but also to transfer their knowledge to students of medical and veterinary faculties of universities in various cities of Russia, students of the St. Petersburg Military medical Academy and military doctors. I.I. Mechnikov and N.F. Gamalea were great friends and colleagues of Pasteur for many years. Together with Pasteur, they made a great contribution to the prosperity of the Paris Institute and the maintenance of the glory of its founder. The role of these scientists in the world heritage in the field of immunology and microbiology is difficult to overestimate. Associate I.I. Mechnikova was also D.K. Zabolotny, who managed to organize the departments of microbiology and epidemiology in several higher educational institutions of Russia and Ukraine. And, of course, the unsurpassed contribution to the organization of the Pasteur Institute in Russia on the model of the Paris Institute belongs to G.D. Belonovsky. Thanks to his efforts, the Sero-diagnostic laboratory gradually developed into the St. Petersburg Pasteur Institute. Many disciples of Pasteur laid the foundation of a number of scientific areas in Russia: microbiology, immunology, toxicology, hygiene. Thanks to the efforts of enthusiasts among the followers of Louis Pasteur managed to establish in Russia (St. Petersburg) Institute, similar to Paris, also named after him. Each of the disciples of Pasteur thanks to selfless work was able to prove his high rank and make a significant contribution to the development of science for the health of the population of the Homeland.

scholarly journals Towards a Reconsrtuction of Historical Materialism. IV: Legitimation

2016 ◽  
Vol 18 (1) ◽  
pp. 6-35
Author(s):  
Jurgen Habermas
Keyword(s):  
Social Identity ◽  
Social Theory ◽  
Significant Contribution ◽  
Historical Materialism ◽  
Contemporary State ◽  
Wide Range ◽  
German Philosopher ◽  
Marxist Concept ◽  
Contemporary Social Theory

The book of world-known German philosopher Jurgen Habermas is devoted to the Marxist social theory and in general to potential of the evolutionary concept of society. A wide range of topics is comprised: from the role of philosophy in Marxism and rational and ethical foundations of social identity to comparative theories and problem of legitimacy. J.Habermas does not only critically rethink Marxist concept, but builds a coherent theoretical alternative to it. The power of the book is that the key problems of social theory are considered not only in the abstract plane, but in the context of contemporary, keen, topical socio-political challenges. Namely the nature of current social crises, conflicts of legitimation of the contemporary state, the morality of power, the effect of innovations etc. The book has become not only one of the classical samples of Marxism analysis, but it was recognized significant contribution to contemporary social theory.

scholarly journals Do Saudi Learners of English Recognize the Benefits of Consciousness-raising Tasks and Communicative Tasks?

2020 ◽  
Vol 13 (6) ◽  
pp. 172
Author(s):  
Adnan Mukhrib
Keyword(s):  
Group Dynamics ◽  
Significant Contribution ◽  
School Context ◽  
Consciousness Raising ◽  
Individual Variations ◽  
Wide Range ◽  
Perceptions Of Students ◽  
Ability Groups ◽  
Actual Learning

This study examined perceptions of students of the benefits of consciousness-raising tasks (CRT) and communicative tasks (CT) when compared with actual learning outcomes in a Saudi secondary school context. Qualitative data were collected from 60 Saudi speaking learners of English, at various proficiency levels, who had engaged in a sequence of collaborative speaking and writing tasks. The results showed the value of the TBL approach which was not in question but makes a significant contribution regarding the importance of the role of interaction in mixed ability groups. The findings indicate that there was a variation in outcomes particularly in terms of how the students perceived the benefits and contribution of the intervention type to their learning. In addition, there was a further impact from the sociolinguistic context of the interaction, which indicates the role of group dynamics and individual variations of Saudi learners. This implies that fluency and accuracy during sociolinguistic interaction is influenced by a wide range of features than cannot be assessed through traditional fluency measures alone. The findings therefore lend support for a TBL approach to maintain the development of fluency, accuracy, and learning.

Concentration Dependence of Photoluminescence and Electroluminescence in 2,5 Bis[2'-(4”-Hydroxyhexanol Benzyl)-l'-Ethyl]3,4-Dibutyl Thiophenes

1997 ◽  
Vol 488 ◽  
Author(s):  
S. Blumstengel ◽  
I. Sokolik ◽  
R. Dorsinville ◽  
D. Voloschenko ◽  
M. He ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Concentration Dependence ◽  
Doping Concentration ◽  
Visible Spectrum ◽  
Concentration Quenching ◽  
Luminescence Spectra ◽  
Pure Material ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Absorption And Luminescence Spectra

AbstractA new thiophene-based compound 2,5 bis[2'-(4”-hydroxyhexanol benzyl)-l'-ethyl]3,4-dibutyl thiophene (HBDT) as well as a copolymer (HBDT-PU) consisting of alternating HBDT and urethane spacer units were synthesized. Absorption and luminescence properties of both compounds were studied in solution and in different polymer matrices. Absorption and luminescence spectra of HBDT and HBDT-PU coincide indicating that emission in HBDT-PU occurs from the thiopene containing unit. Photoluminescence (PL) is emitted in the blue-green region of the visible spectrum with a maximum at 460 nm. The PL efficiency of both compounds is strongly enhanced when dispersed in a PVK or PMMA matrix indicating that concentration quenching occurs in the pure material. Light emitting devices were fabricated utilizing a PVK/PBD blend doped with HBDT and HBDT-PU at different concentrations as emitter material. The electroluminescence (EL) spectra coincided with the PL spectra of HBDT indicating that EL emission originates from the dopant molecules. The dependence of the EL efficiency on the doping concentration was measured and found to be close to the concentration dependence of the PL quantum yield.

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