In this study phenolic compounds extraction from grape byproducts was conducted using pure water as a solvent. High temperatures and low time incubation periods were used in the aim of reducing the cost of the process...In this study phenolic compounds extraction from grape byproducts was conducted using pure water as a solvent. High temperatures and low time incubation periods were used in the aim of reducing the cost of the process and heightening the phenolic compounds yield. Response surface methodology (RSM) was realized to study the effect of time and temperature on crushed and uncrushed grape pomace. The phenolic content was evaluated considering the quantity (total phenolics (TPC), flavonoids (FC), total monomeric anthocyanins (TMA) and tannins (TC)), and quality (antiradical activity (AA) and antioxidant capacity (AC)) of the extracts. High temperature low time extraction design used in this study was compared to the extraction process at moderate temperatures with relatively long periods of time. This was proved to ameliorate the quantitative extraction of phenolic compounds from grape pomace without affecting their bioactivity. Moreover, multiple response optimization showed the optimal extraction parameters to be 81?C and 140 minutes for the unmilled pomace samples, and 88?C and 5 minutes for the milled. TPC, FC, TMA, TC, AA and AC are almost the same for both optimums. Thus the possibility of replacing the milling process by the extraction time prolongation (for the unmilled pomace) of 135 minutes seems to be very plausible. HPLC analysis showed different quantity and diversity of extracted phenolics for the optimums. However this difference did not significantly affect the overall activity, showing that PC in the different extracts act in complete synergy all together leading to important biological properties. The obtained results using the extraction strategy adopted in this work could lead to several industrial applications.展开更多
The current work concerns the optimization process of phenolic compounds solid liquid extraction from grape byproducts at high temperatures and short incubation times. The effect of five experimental parameters (solid...The current work concerns the optimization process of phenolic compounds solid liquid extraction from grape byproducts at high temperatures and short incubation times. The effect of five experimental parameters (solidliquid ratio, particle size, time, temperature and solvent mixture) mostly believed to affect the extraction process was undertaken. A first response surface methodology experimental design was used to optimize the solid-liquid ratio and milling time parameters. A second design was used for the optimization of the quantitative and qualitative parameters. The quantitative parameters studied are: total phenolic compounds, flavonoid content, total monomeric anthocyanin composition and tannin concentration. The qualitative parameters analyzed are: antiradical activity and antioxidant capacity. The second design was based on the use of time, temperature and solvent mixture as optimization parameters. The assays were first conducted separately revealing the best experimental conditions for the maximization of each response variable alone. A simultaneous response surface methodology of all the responses taken together was then conducted, showing the optimal extraction conditions to be: 93 minutes at 94?C and in 66% ethanol/water solvent. The maximal response values obtained for each parameter are: Total Phenolic Compounds yield (5.5 g GAE/100g DM), Flavonoid Content (5.4 g GAE/100g DM), Total Monomeric Anthocyanin yield (70.3 mg/100g DM), Tannin Concentration (12.3 g/L), Antiradical Activity (67.3%) and Total Antioxidant Capacity (393 mgAAE/L). All of the optimal values were acquired at 3 mL/g solid-liquid ratio and 6.8 min milling time. The obtained extracts could be used as natural bioactive compounds in several industrial applications.展开更多
Botrytis cinerea is a necrotrophic fungusth at a ffects various plant species.Chemical control is an ecessity and as much as possible,eco-friendly conditions and bioresources to obtain these chemicals should be used.I...Botrytis cinerea is a necrotrophic fungusth at a ffects various plant species.Chemical control is an ecessity and as much as possible,eco-friendly conditions and bioresources to obtain these chemicals should be used.In this context,a series of products w as obtained from salicylaldehyde using zinc as a powerful reagent and tested for antifungal activity against Botrytis cinerea.展开更多
The aims of this work turn towards the valorization of the underutilized Raw Sugar Beet Pulp by-product to produce white Cellulose Microfibers(CMFs),and its potential effect as a reinforcement for the development of H...The aims of this work turn towards the valorization of the underutilized Raw Sugar Beet Pulp by-product to produce white Cellulose Microfibers(CMFs),and its potential effect as a reinforcement for the development of High-Density Polyethylene(HDPE)composites.Pure CMFs were first obtained by subjecting raw SBP to alkali and bleaching treatments.Several characterization techniques were performed to confirm the successful removal of the amorphous compounds from the surface of individual fibers,including SEM,XRD,TGA,and FT-IR analysis.Various CMF loadings(5–10 wt%)were incorporated as bio-fillers into HDPE polymer to evaluate their reinforcing ability in comparison to raw and alkali-treated SBP using twin-screw extrusion followed by injection molding.Styrene–(Ethylene–Butene)–Styrene Three-Block Co-Polymer Grafted with Maleic Anhydride was used as a compatibilizer to improve the interfacial adhesion between fibers and the matrix.Thermal,mechanical,and rheological properties of the produced composite samples were investigated.It was found that the Young’s modulus were gradually increased with increasing of fibers loadings,with a maximum increase of 30%and 26%observed for composite containing 10 wt%of CMFs and raw SBP,respectively,over neat HDPE.While,the use of coupling agent enhances the ductile behavior of the composites.It was also found that all fiber improves the hardness and toughness behavior of all reinforced composites as well as the complex modulus particularly at 10 wt%.The thermal stability slightly increases with the addition of fibers.This study demonstrates a new route for the valorization of SBP by-products.These fibers can be considered as a valuable bio-fillers candidate for the development of composite materials with enhanced properties.展开更多
Due to their beneficial effects on human health, phenolic compounds are increasingly attracting the attention of scientists and researchers all over the world. The main interest is in the extraction process of those n...Due to their beneficial effects on human health, phenolic compounds are increasingly attracting the attention of scientists and researchers all over the world. The main interest is in the extraction process of those natural plant-originated compounds from fruits, vegetables and plant wastes, namely grape wastes, in which phenolic compounds are the most abundant secondary metabolites. This waste exploitation not only re-assimilates those byproducts into the food cycle, but also avoids major environmental problems. Herein, the optimization of the phenolic compounds concentration and free radical scavenging activity from Cabernet Sauvignon grape byproducts was conducted, using multi-response surface methodology. A conventional solid-liquid extraction process was performed with pure water as a solvent to study the effects of both time and temperature on the procedure. The maximal phenolic compounds concentration (878.9 mg/L) was reached at 47℃ after 30 hours while the optimal free radical scavenging activity (41.15%) was obtained at 30℃ after 20 hours. A multi-response surface methodology compromised between the quantity and the quality of the extracted phenolics, and the parameters maximizing both responses were obtained at 37℃ and 28 hours. This low-cost and energy saving process provides an excellent tool for further industrial applications.展开更多
S-ALOHA （Slotted ALOHA） random access protocol is a widely used protocol mainly for the transmission of short packets in wireless networks. Most papers consider either an infinite population model where the impact o...S-ALOHA （Slotted ALOHA） random access protocol is a widely used protocol mainly for the transmission of short packets in wireless networks. Most papers consider either an infinite population model where the impact of the backoff protocol cannot be adequately evaluated or a finite population model where the number of nodes is fixed. In this letter, a combination of both models is proposed using the time-scale decomposition technique. This methodology allows to study the system under more realistic conditions where the dynamics of users enter and leaving the system are reflected on the performance of the system as well as the impact of the backoff protocol. Also, it allows studying the system in non-saturation conditions. The proposed methodology divides the analysis in two parts： packet-level and connection-level. This analysis renders suitable results when the time scale of the packet level and connection level statistics is different. On the other hand, when these scales are similar, the proposed methodology is no longer suited.展开更多
Quercetin is a bioflavonoid compound with low water solubility in both foods and the gastrointestinal tract,which limits the exploitation of its health-promoting properties.This study aims to formulate solid dispersio...Quercetin is a bioflavonoid compound with low water solubility in both foods and the gastrointestinal tract,which limits the exploitation of its health-promoting properties.This study aims to formulate solid dispersions(SDs)of quercetin with hydrophilic polyethylene glycol PEG matrices,using the melt-mixing method,to improve the dissolution and antioxidant activity of quercetin.Initially,the total Gibbs free energy for different binary mixtures was modelled to predict the miscibility of the compounds.Then,the physicochemical properties of the formulated SDs were characterised and dissolution tests and antioxidant activity measurements were performed in vitro to evaluate the improved profiles and antioxidant activity of the SDs developed.The group contribution methods of Hoy and Van Krevelen and Hoftyzer,used for PEG solubility parameter calculations,presented a suitable prediction of interaction and miscibility behaviour.The results suggested the presence of amorphous quercetin precipitates in the crystalline matrix of PEG 4000 and PEG 6000,and the formation of an amorphous SD between quercetin and PEG 1000.These formulations achieved good radical scavenging activity and better dissolution,especially the quercetin-PEG 1000 SDs.展开更多
One novel nucleoside analogue having a hex-5-enyl group and an allyl group in the 5'-C and 3-N position was synthesized regioand diastereoselectively from D-glucose in twelve steps.In order to reach a particular c...One novel nucleoside analogue having a hex-5-enyl group and an allyl group in the 5'-C and 3-N position was synthesized regioand diastereoselectively from D-glucose in twelve steps.In order to reach a particular conformation of nucleosides the nucleoside formation of restricted cyclonucleoside analogues was studied via Ring-Closing Metathesis.展开更多
文摘In this study phenolic compounds extraction from grape byproducts was conducted using pure water as a solvent. High temperatures and low time incubation periods were used in the aim of reducing the cost of the process and heightening the phenolic compounds yield. Response surface methodology (RSM) was realized to study the effect of time and temperature on crushed and uncrushed grape pomace. The phenolic content was evaluated considering the quantity (total phenolics (TPC), flavonoids (FC), total monomeric anthocyanins (TMA) and tannins (TC)), and quality (antiradical activity (AA) and antioxidant capacity (AC)) of the extracts. High temperature low time extraction design used in this study was compared to the extraction process at moderate temperatures with relatively long periods of time. This was proved to ameliorate the quantitative extraction of phenolic compounds from grape pomace without affecting their bioactivity. Moreover, multiple response optimization showed the optimal extraction parameters to be 81?C and 140 minutes for the unmilled pomace samples, and 88?C and 5 minutes for the milled. TPC, FC, TMA, TC, AA and AC are almost the same for both optimums. Thus the possibility of replacing the milling process by the extraction time prolongation (for the unmilled pomace) of 135 minutes seems to be very plausible. HPLC analysis showed different quantity and diversity of extracted phenolics for the optimums. However this difference did not significantly affect the overall activity, showing that PC in the different extracts act in complete synergy all together leading to important biological properties. The obtained results using the extraction strategy adopted in this work could lead to several industrial applications.
文摘The current work concerns the optimization process of phenolic compounds solid liquid extraction from grape byproducts at high temperatures and short incubation times. The effect of five experimental parameters (solidliquid ratio, particle size, time, temperature and solvent mixture) mostly believed to affect the extraction process was undertaken. A first response surface methodology experimental design was used to optimize the solid-liquid ratio and milling time parameters. A second design was used for the optimization of the quantitative and qualitative parameters. The quantitative parameters studied are: total phenolic compounds, flavonoid content, total monomeric anthocyanin composition and tannin concentration. The qualitative parameters analyzed are: antiradical activity and antioxidant capacity. The second design was based on the use of time, temperature and solvent mixture as optimization parameters. The assays were first conducted separately revealing the best experimental conditions for the maximization of each response variable alone. A simultaneous response surface methodology of all the responses taken together was then conducted, showing the optimal extraction conditions to be: 93 minutes at 94?C and in 66% ethanol/water solvent. The maximal response values obtained for each parameter are: Total Phenolic Compounds yield (5.5 g GAE/100g DM), Flavonoid Content (5.4 g GAE/100g DM), Total Monomeric Anthocyanin yield (70.3 mg/100g DM), Tannin Concentration (12.3 g/L), Antiradical Activity (67.3%) and Total Antioxidant Capacity (393 mgAAE/L). All of the optimal values were acquired at 3 mL/g solid-liquid ratio and 6.8 min milling time. The obtained extracts could be used as natural bioactive compounds in several industrial applications.
基金ESCOM for fundingWallonie-Bruxelles International et le Fonds National de la Recherche Scientifique pour la communaute francaise de BelgiqueMinistere des Affaires Etrangeres et du Developpement International(MAEDI)et Ambassade de France en Belgique pour la France and by the Region of Picardie,France(cofunding of equipment under CPER 2007-2020 project)。
文摘Botrytis cinerea is a necrotrophic fungusth at a ffects various plant species.Chemical control is an ecessity and as much as possible,eco-friendly conditions and bioresources to obtain these chemicals should be used.In this context,a series of products w as obtained from salicylaldehyde using zinc as a powerful reagent and tested for antifungal activity against Botrytis cinerea.
基金financial assistance of the Moroccan National Center for Scientific and Technical Research(CNRST)toward this research is hereby acknowledgedThanks to Abou El Kacem QAISS from Moroccan Foundation for Advanced Science,Innovation and Research(MAScIR)for his help to elaborate and characterize all our composites.
文摘The aims of this work turn towards the valorization of the underutilized Raw Sugar Beet Pulp by-product to produce white Cellulose Microfibers(CMFs),and its potential effect as a reinforcement for the development of High-Density Polyethylene(HDPE)composites.Pure CMFs were first obtained by subjecting raw SBP to alkali and bleaching treatments.Several characterization techniques were performed to confirm the successful removal of the amorphous compounds from the surface of individual fibers,including SEM,XRD,TGA,and FT-IR analysis.Various CMF loadings(5–10 wt%)were incorporated as bio-fillers into HDPE polymer to evaluate their reinforcing ability in comparison to raw and alkali-treated SBP using twin-screw extrusion followed by injection molding.Styrene–(Ethylene–Butene)–Styrene Three-Block Co-Polymer Grafted with Maleic Anhydride was used as a compatibilizer to improve the interfacial adhesion between fibers and the matrix.Thermal,mechanical,and rheological properties of the produced composite samples were investigated.It was found that the Young’s modulus were gradually increased with increasing of fibers loadings,with a maximum increase of 30%and 26%observed for composite containing 10 wt%of CMFs and raw SBP,respectively,over neat HDPE.While,the use of coupling agent enhances the ductile behavior of the composites.It was also found that all fiber improves the hardness and toughness behavior of all reinforced composites as well as the complex modulus particularly at 10 wt%.The thermal stability slightly increases with the addition of fibers.This study demonstrates a new route for the valorization of SBP by-products.These fibers can be considered as a valuable bio-fillers candidate for the development of composite materials with enhanced properties.
文摘Due to their beneficial effects on human health, phenolic compounds are increasingly attracting the attention of scientists and researchers all over the world. The main interest is in the extraction process of those natural plant-originated compounds from fruits, vegetables and plant wastes, namely grape wastes, in which phenolic compounds are the most abundant secondary metabolites. This waste exploitation not only re-assimilates those byproducts into the food cycle, but also avoids major environmental problems. Herein, the optimization of the phenolic compounds concentration and free radical scavenging activity from Cabernet Sauvignon grape byproducts was conducted, using multi-response surface methodology. A conventional solid-liquid extraction process was performed with pure water as a solvent to study the effects of both time and temperature on the procedure. The maximal phenolic compounds concentration (878.9 mg/L) was reached at 47℃ after 30 hours while the optimal free radical scavenging activity (41.15%) was obtained at 30℃ after 20 hours. A multi-response surface methodology compromised between the quantity and the quality of the extracted phenolics, and the parameters maximizing both responses were obtained at 37℃ and 28 hours. This low-cost and energy saving process provides an excellent tool for further industrial applications.
文摘S-ALOHA （Slotted ALOHA） random access protocol is a widely used protocol mainly for the transmission of short packets in wireless networks. Most papers consider either an infinite population model where the impact of the backoff protocol cannot be adequately evaluated or a finite population model where the number of nodes is fixed. In this letter, a combination of both models is proposed using the time-scale decomposition technique. This methodology allows to study the system under more realistic conditions where the dynamics of users enter and leaving the system are reflected on the performance of the system as well as the impact of the backoff protocol. Also, it allows studying the system in non-saturation conditions. The proposed methodology divides the analysis in two parts： packet-level and connection-level. This analysis renders suitable results when the time scale of the packet level and connection level statistics is different. On the other hand, when these scales are similar, the proposed methodology is no longer suited.
文摘Quercetin is a bioflavonoid compound with low water solubility in both foods and the gastrointestinal tract,which limits the exploitation of its health-promoting properties.This study aims to formulate solid dispersions(SDs)of quercetin with hydrophilic polyethylene glycol PEG matrices,using the melt-mixing method,to improve the dissolution and antioxidant activity of quercetin.Initially,the total Gibbs free energy for different binary mixtures was modelled to predict the miscibility of the compounds.Then,the physicochemical properties of the formulated SDs were characterised and dissolution tests and antioxidant activity measurements were performed in vitro to evaluate the improved profiles and antioxidant activity of the SDs developed.The group contribution methods of Hoy and Van Krevelen and Hoftyzer,used for PEG solubility parameter calculations,presented a suitable prediction of interaction and miscibility behaviour.The results suggested the presence of amorphous quercetin precipitates in the crystalline matrix of PEG 4000 and PEG 6000,and the formation of an amorphous SD between quercetin and PEG 1000.These formulations achieved good radical scavenging activity and better dissolution,especially the quercetin-PEG 1000 SDs.
文摘One novel nucleoside analogue having a hex-5-enyl group and an allyl group in the 5'-C and 3-N position was synthesized regioand diastereoselectively from D-glucose in twelve steps.In order to reach a particular conformation of nucleosides the nucleoside formation of restricted cyclonucleoside analogues was studied via Ring-Closing Metathesis.
