Development of high throughput microfluidic platforms for the measurement of the protein solution thermodynamic properties

Les travaux de cette thèse portent sur le développement de système microfluidiques génériques pour la mesure de propriétés thermodynamiques de solutions de proteines. Un procédé simple de fabrication de puces microfluidiques résistantes à la pression ainsi qu'à la majorité des solvants organiques a été développé. En outre, les propriétés de surface des microcanaux peuvent être ajustées afin de générer des émulsions eau dans huile ou huile dans l'eau. L'étude des interactions proteines-proteines en solution a été réalisée en couplant ces dispositifs expérimentaux à la diffusion de rayonnement X aux petits angles. Avec seulement quelque milligramme de produit, les données expérimentales obtenues ont permis de calculer le second coefficient du Viriel, grandeur thermodynamique permettant de quantifier les interactions entre protéines. Une nouvelle approche expérimentale a également été développée afin de déterminer l'équation d'état du lysozyme, équation reliant la pression osmotique à la fraction volumique. Ce système microfluidique est basé sur le transfert de matière entre d'une phase dispersée vers une phase continue. Dans une certaine gamme d'activité de l'eau, l'équation d'état obtenu est en bon accord avec les données de la littérature. Afin de relier la dynamique du transfert aux propriétés thermodynamique du système une première approche de modélisation est proposée. Cette approche a pour but de déterminer l'équation d'état de la protéine avec une seule goutte.This thesis is focused on the development of more efficient protocols and systems, by means of generic microfluidic platforms for measuring thermodynamic properties of protein solutions. A simple method for manufacturing pressure-resistant microfluidic structures with high chemical resistance has been developed. In addition, the surface properties of the fabrication materials can be adjusted to generate hydrophilic and hydrophobic surfaces allowing to generate aqueous and non-aqueous emulsions. On a first approach, the study of protein-protein interactions in solution was successfully performed using just a few milligrams of product by coupling a microfluidic platform, developed ad-hoc for this application, to small angle X-ray scattering. The obtained experimental data were used to calculate the second virial coefficient, thermodynamic parameter which quantifies protein interactions. A second and new experimental approach has also been developed to determine protein equations of state (EOS), which relate protein osmotic pressure to its volume fraction in solution. This novel methodology is based on the study of the mass transfer between a dispersed and a continuous phase, which are generated and controlled by means of a microfluidic setup. For a given range of water activity, the resulting EOS was found to be in good agreement with data reported in the literature. To link the mass transfer dynamics to the thermodynamic properties of the system a first modeling approach was proposed. This approach aims to determine the EOS of the protein using a single droplet

Ultrasonic-Assisted Cathodic Plasma Electrolysis Approach for Producing of Graphene Nanosheets

In this chapter, we review on the production of graphene by ultrasonic-assisted cathodic plasma electrolysis approach which involves a combination process of conventional electrolysis and plasma at ambient pressure and moderate temperature. Firstly, we review on the techniques for electrochemical preparation of graphene. Then, we briefly describe plasma electrolysis approach for producing of graphene. The mechanism, advantages, and disadvantages of this technique are discussed in detail

Influence of Reaction Temperature on Optical Property of Mn-Doped ZnS Nanoparticles

The reaction temperature has essential effect on quality of the product synthesized by hydrothermal method. We report here the variation of the optical characteristics of Mn-doped ZnS nanocrystallites prepared by mean of the stated method from Zn(CH$_{3}$COO)$_{2}$.2H$_{2}$O, Mn(CH$_{3}$COO)$_{2}$.4H$_{2}$O and Na$_{2}$S$_{2}$O$_{3}$.5H$_{2}$O as the precursors. The reaction temperature was set to vary from 120\r{}C to 240\r{}C at a constant reaction time of 15 hours. The XRD patterns showed that, for the reaction temperature range from 120 to 160\r{}C, the obtained products possessed a cubic $T_d^2 - F\overline 4 3m$ and a wurtzite $C_{6v}^4 - P6_3 mc$structure, in which the cubic phase was dominant. At the temperature range from 180 to 240\r{}C, the structures exhibited a cubic phase with the lattice constant increased from 5.41 to 5.43 {\AA}. The photoluminescence spectra showed that with the increase of reaction temperature from 120 to 240\r{}C the intensity of a blue band around 425 - 500 nm (attributed to both Zn, S vacancies) gradually decreased while the intensity of a yellow-orange band at 585 nm (attributed to the $^{4}$T$_{1}(^{4}$G) - $^{6}$A$_{1}(^{6}$S) transition of Mn$^{2 + }$ ions) was enhanced and reached maximum at 220\r{}C. The excitation spectra of the 585 nm band recorded at 160\r{}C showed a band at 335 nm which should be assigned to the near band-edge absorption. With increasing temperature to 200-240\r{}C the new bands appeared at 390, 430, 467, 494 nm. The intensity of these bands increased with temperature and achieved the maxima at 220\r{}C. They should be attributed to the absorption transitions of electrons from ground state $^{6}$A$_{1}(^{6}$S) to excited states$^{ 4}$E($^{4}$D); $^{4}$T$_{2}(^{4}$D); $^{4}$A$_{1}(^{4}$G) - $^{4}$E($^{4}$G); $^{4}$T$_{2}(^{4}$G) of Mn$^{2 + }$(3d$^{5})$ ions, respectively. The bands at 467, 494 nm only exposed clearly in the absorption spectra at 220\r{}C and 240\r{}C

Indicators for TQM 4.0 model: Delphi Method and Analytic Hierarchy Process (AHP) analysis

Anchoring on Socio-technical system (STS) theory, this study applied Delphi and analytic hierarchy process (AHP) techniques to explore the key factors and specific indicators of the TQM 4.0 model implementation in manufacturing enterprises. An analysis of two Delphi rounds through experts who are academia, consultants, and production/quality supervisors/managers found ten factors and 41 indicators. In the third round, the study weighted the importance of each factor and indicator through an analysis of the AHP technique. The research suggested that social factors were more important than technical factors. Importantly, the findings indicated three key factors of the TQM 4.0 model, including top management, quality culture 4.0, and integrating sustainable development. Furthermore, the study revealed that top management commitment, quality-driven mindfulness, and employee empowerment were specified as the most critical indicators of the TQM 4.0 model. Results could be valuable for both researchers and practitioners in assessing TQM 4.0 implementation in the manufacturing sector in the future. © 2022 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.Tomas Bata University in Zlin [VaV-IP-RO/2020/01

Chemical Components of Essential Oils From the Leaves of Seven Species Belonging to Rutaceae Family from Binh Chau-Phuoc Buu Nature Reserve, Vietnam

Several plant species of the Rutaceae family are medicinal plants, oil bearing and food crops. To provide more information for utilization of some species of this family in Binh Chau-Phuoc Buu Nature Reserve, we extracted essential oils from the leaves of seven species of the Rutaceae family: Acronychia pedunculata (L.) Miq., Atalantia citroides Pierre ex Guillaumin, Clausena excavata Burm.f., Glycosmis pentaphylla (Retz.) DC., Luvunga scandens (Roxb.) Buch.-Ham. ex Wight & Arn, Melicope pteleifolia (Champ. ex Benth.) T.G. Hartley, and Micromelum sp., via hydrodistillation, and identified their components using GC/MS analysis. A total of 60 compounds were identified from essential oils of seven species. The main components of the essential oils isolated from five species, including A. pedunculata, C. excavata, M. pteleifolia, G. pentaphylla, and Micromelum sp., were caryophyllene (57.63% and 55.41% in A. pedunculata and C. excavata, respectively), 1,9-decadiyne (32.59%, M. pteleifolia), β-ocimene (23.10%, G. pentaphylla), and 3-carene (58.03%, Micromelum sp.). Additionally, this study revealed the chemical composition of essential oils of L. scandens and A. citroides for the first time. The main constituent of A. citroides was 7-oxabicyclo[4.1.0] heptane, 3-oxiranyl- (53.91%) and that of L. scandens was caryophyllene (34.66%). These findings provide the basis for further application of these species in medicine

Extraction of Polyphenols from Mentha aquatica Linn. var. crispa

Mentha aquatica Linn. var. crispa is commonly used as a spice in many Asian countries. Although its biological activities, such as its applications, antimicrobial properties, have been studied, its antioxidation properties have not been investigated. This study establishes the most suitable extraction conditions concerning the independent variables affecting the total polyphenol content (TPC) and antioxidant activity (AA) of M. aquatica extract (stem and leaf). Investigated factors include the type of solvent used; solvent concentration, the ratio of raw material to solvent, extraction time and extraction temperature. The efficiency of polyphenol extraction was evaluated by TPC and AA through the ability to neutralize the free radicals 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2\u27-azinobis (3-ethylbenzothiazoline-6- sulfonic acid) (ABTS), and the ferric reducing antioxidant power (FRAP) was used as the evaluation indicator. The results have shown that acetone at a concentration of 50%, at a ratio of 1:20 (w/v), extraction time of 2 h and a temperature of 40 °C give the highest values of TPC and AA, with values of 120.92 mg GAE g-1 dw for TPC, 169.36 μmol TE g-1 dw by DPPH assay, 264.03 μmol by ABTS assay, and 425.35 μmol Fe2+ g-1 dw by FRAP assay. This study demonstrates that extracts of M. aquatica can be used for research as food antioxidant

Extraction of Polyphenols from Mentha aquatica Linn. var. crispa

Mentha aquatica Linn. var. crispa is commonly used as a spice in many Asian countries. Although its biological activities, such as its applications, antimicrobial properties, have been studied, its antioxidation properties have not been investigated. This study establishes the most suitable extraction conditions concerning the independent variables affecting the total polyphenol content (TPC) and antioxidant activity (AA) of M. aquatica extract (stem and leaf). Investigated factors include the type of solvent used; solvent concentration, the ratio of raw material to solvent, extraction time and extraction temperature. The efficiency of polyphenol extraction was evaluated by TPC and AA through the ability to neutralize the free radicals 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2\u27-azinobis (3-ethylbenzothiazoline-6- sulfonic acid) (ABTS), and the ferric reducing antioxidant power (FRAP) was used as the evaluation indicator. The results have shown that acetone at a concentration of 50%, at a ratio of 1:20 (w/v), extraction time of 2 h and a temperature of 40 °C give the highest values of TPC and AA, with values of 120.92 mg GAE g-1 dw for TPC, 169.36 μmol TE g-1 dw by DPPH assay, 264.03 μmol by ABTS assay, and 425.35 μmol Fe2+ g-1 dw by FRAP assay. This study demonstrates that extracts of M. aquatica can be used for research as food antioxidant