A collection of lactic acid bacteria isolates from fish viscera was studied and investigated regarding to their functional properties and safety aspects. From these, three isolates GM1, GM2 and GM3 were identified as ...A collection of lactic acid bacteria isolates from fish viscera was studied and investigated regarding to their functional properties and safety aspects. From these, three isolates GM1, GM2 and GM3 were identified as Enterococcus feacium species using molecular methods. Partial Amplified rDNA Restriction Analysis (partial ARDRA) with restriction enzyme HaeIII separated these isolates into distinctive group which suggest genotypic variability within enterococci strains isolated from fish viscera. The three strains GM1, GM2 and GM3 exhibited antimicrobial activity. Indeed strains have been shown to produce bacteriocins with inhibitory effect against food spoilage bacteria and pathogenic fish including Carnobacterium maltaromaticum. The molecular mass of bacteriocin, as calculated by tricine-SDS-PAGE, was found to be 4.5 kDa. All isolates were tested positive upon PCR amplification of enterocin A structural gene. Investigations of antibiotic resistance show that the isolates were mostly sensitive to several antibiotics (ampicillin, penicillin, tetracycline, gentamycine) and resistance to rifampicin. All isolates grow in esculin azide agar as a selective medium for enumeration of probiotic enterococci. This study suggests that our strains can be employed as probiotic or to improve the safety of food products.展开更多
Objective: To investigate phenolics, fatty acids composition and biological activities of various extracts and fractions of Malaysian Aaptos aaptos. Methods: Fatty acid methyl ester was analyzed by gas chromatography-...Objective: To investigate phenolics, fatty acids composition and biological activities of various extracts and fractions of Malaysian Aaptos aaptos. Methods: Fatty acid methyl ester was analyzed by gas chromatography-flame ionization detector. Antioxidant activity was determined using 2,2-diphenyl-picrylhydrazyl radical scavenging assay and total phenolics content by Folin-Ciocalteu procedure. Vero cells viability was evaluated using methyl thiazole tetrazolium and the inactivation of herpes simplex virus type 1 by neutral red uptake assay. p-Hydroxybenzamide isolated by column chromatography was characterized by utilizing nuclear magnetic resonance spectroscopy and electron impact mass spectrometry. Results: The chloroform, ethyl acetate and methanol extracts of Aaptos aaptos produced higher portions of straight-chain saturated fatty acid, while hexane extract mainly consisted of unsaturated fatty acid. The five majors of fatty acid methyl ester were identified as behenic acid, cis-10-heptadecenoic acid and cis-10-pentadecenoic acids, palmitic acid and tricosanoic acid. In addition, among all organic extracts, chloroform extract inactivated herpes simplex virus type 1 while exhibited weak cytotoxic activity against normal Vero cells and also exhibited strong cytotoxic activity on HL-60, MCF-7, K562, CEM-SS and WEHI-3 B cells. A phenolic compound, p-hydroxybenzamide was also isolated from the sponge. Conclusions: Aaptos aaptos could be a source to derive the potential antiviral and anticancer agents. However, further studies are needed to determine the mechanism involved in the process.展开更多
Cameroon lives in the era of great infrastructures in order to reach the economic emergence by 2035. These infrastructures require a solid framework of energy provisions from many natural energy sources and resources ...Cameroon lives in the era of great infrastructures in order to reach the economic emergence by 2035. These infrastructures require a solid framework of energy provisions from many natural energy sources and resources that the country possesses. Speaking of natural energy resources, the country is particularly gifted by solar energy potential in the far north. This region of the land is densely populated but much of the populations do not have access to electricity since they live in remote areas far from national electricity grid. Solar thermal energy appears then as real potential to fulfill the growing demand of energy and reduce fossil fuel use dependence. Moreover, it would also be a grandiose opportunity for hospitals in these regions to provide hot water for Sterilization. As the design of a solar thermal plant strongly relies on the potential of direct solar irradiance and the performance of a solar parabolic trough collector (PTC) estimated under the local climate conditions, in this paper, we annually compute direct solar radiation based on monthly average Linke turbidity factor and various tracking modes in two chosen sites in the far north region of Cameroon. Also, a detailed two dimensional numerical heat transfer analysis of a PTC has been performed. The receiver has been divided into many control volumes along his length and each of them is a column consisting of glass, vacuum, absorber and fluid along which mass and energy balance have been applied. Direct solar irradiation, ambient temperature optical and thermal analyses of the collector receiver takes into consideration all modes of heat transfer and the nonlinear algebraic equations were solved simultaneously at each instant during a day of computation using Engineering Equation Solver (EES). To validate the numerical results, the model was compared with experimental data obtained from Sandia National Laboratory (SNL). It has shown a great concordance with a maximum relative error value of 0.35% and thermal efficiency range of systems about 66.67% - 73.2%. It has also been found that the one axis polar East-West and horizontal East-West tracking with 96% and 94% of full tracking mode respectively, were most suitable for a parabolic trough collector throughout the whole year in the two towns considered.展开更多
The use of air scrubbers to reduce ammonia (NH<sub>3</sub>) emissions from buildings on pig farms is one of the most promising techniques in the GÖteborg protocol and other European regulations includ...The use of air scrubbers to reduce ammonia (NH<sub>3</sub>) emissions from buildings on pig farms is one of the most promising techniques in the GÖteborg protocol and other European regulations including the Industrial Emission Directive. In France, some air scrubbers are currently used on pig farms, mainly to reduce odours from livestock buildings. However, recent research revealed the production of N<sub>2</sub>O resulting from the treatment of air from pig buildings. In this context, a two-month study was conducted on a pig farm with 750 places for fattening pigs to check the abatement of NH3 emissions and to assess the possible production of N<sub>2</sub>O during treatment of exhausted air from buildings housing fattening pigs by a air scrubber. Concentrations of NH<sub>3</sub> and N<sub>2</sub>O in the inlet and outlet air of the scrubber were continuously monitored using an Innova 1412 infrared analyzer. With the scrubber operating parameters (airflow, design, size), our results confirmed the production of N<sub>2</sub>O in the order of 5% of NH<sub>3</sub>-N reduced. N<sub>2</sub>O was produced by biological nitrification and/or denitrification inside the air scrubber. Statistical analysis (Pearson’s test) showed that the production of N<sub>2</sub>O was strongly influenced by the rate of airflow and the outside temperature. The abatement of NH<sub>3</sub> emissions from the building was only 33%, i.e. much lower than the 70% - 90% usually cited in the literature.展开更多
This work presents expeditious synthesis of C-glycoside amphiphiles in aqueous media from unprotected di-or mono-saccharides.A Horner-Wadsworth-Emmons/Michael addition/Barbier allylation sequence led to C-glycosides t...This work presents expeditious synthesis of C-glycoside amphiphiles in aqueous media from unprotected di-or mono-saccharides.A Horner-Wadsworth-Emmons/Michael addition/Barbier allylation sequence led to C-glycosides that exhibit hydrotropic properties.The hydrotropic and solubilizing properties of these homoallylic alcohols including a β-C-glycoside moiety as well as additional β-C-glycosidic ketones with a short(C7) alkyl chain are also described and compared with those of commercial O-glucoside references.展开更多
文摘A collection of lactic acid bacteria isolates from fish viscera was studied and investigated regarding to their functional properties and safety aspects. From these, three isolates GM1, GM2 and GM3 were identified as Enterococcus feacium species using molecular methods. Partial Amplified rDNA Restriction Analysis (partial ARDRA) with restriction enzyme HaeIII separated these isolates into distinctive group which suggest genotypic variability within enterococci strains isolated from fish viscera. The three strains GM1, GM2 and GM3 exhibited antimicrobial activity. Indeed strains have been shown to produce bacteriocins with inhibitory effect against food spoilage bacteria and pathogenic fish including Carnobacterium maltaromaticum. The molecular mass of bacteriocin, as calculated by tricine-SDS-PAGE, was found to be 4.5 kDa. All isolates were tested positive upon PCR amplification of enterocin A structural gene. Investigations of antibiotic resistance show that the isolates were mostly sensitive to several antibiotics (ampicillin, penicillin, tetracycline, gentamycine) and resistance to rifampicin. All isolates grow in esculin azide agar as a selective medium for enumeration of probiotic enterococci. This study suggests that our strains can be employed as probiotic or to improve the safety of food products.
文摘Objective: To investigate phenolics, fatty acids composition and biological activities of various extracts and fractions of Malaysian Aaptos aaptos. Methods: Fatty acid methyl ester was analyzed by gas chromatography-flame ionization detector. Antioxidant activity was determined using 2,2-diphenyl-picrylhydrazyl radical scavenging assay and total phenolics content by Folin-Ciocalteu procedure. Vero cells viability was evaluated using methyl thiazole tetrazolium and the inactivation of herpes simplex virus type 1 by neutral red uptake assay. p-Hydroxybenzamide isolated by column chromatography was characterized by utilizing nuclear magnetic resonance spectroscopy and electron impact mass spectrometry. Results: The chloroform, ethyl acetate and methanol extracts of Aaptos aaptos produced higher portions of straight-chain saturated fatty acid, while hexane extract mainly consisted of unsaturated fatty acid. The five majors of fatty acid methyl ester were identified as behenic acid, cis-10-heptadecenoic acid and cis-10-pentadecenoic acids, palmitic acid and tricosanoic acid. In addition, among all organic extracts, chloroform extract inactivated herpes simplex virus type 1 while exhibited weak cytotoxic activity against normal Vero cells and also exhibited strong cytotoxic activity on HL-60, MCF-7, K562, CEM-SS and WEHI-3 B cells. A phenolic compound, p-hydroxybenzamide was also isolated from the sponge. Conclusions: Aaptos aaptos could be a source to derive the potential antiviral and anticancer agents. However, further studies are needed to determine the mechanism involved in the process.
文摘Cameroon lives in the era of great infrastructures in order to reach the economic emergence by 2035. These infrastructures require a solid framework of energy provisions from many natural energy sources and resources that the country possesses. Speaking of natural energy resources, the country is particularly gifted by solar energy potential in the far north. This region of the land is densely populated but much of the populations do not have access to electricity since they live in remote areas far from national electricity grid. Solar thermal energy appears then as real potential to fulfill the growing demand of energy and reduce fossil fuel use dependence. Moreover, it would also be a grandiose opportunity for hospitals in these regions to provide hot water for Sterilization. As the design of a solar thermal plant strongly relies on the potential of direct solar irradiance and the performance of a solar parabolic trough collector (PTC) estimated under the local climate conditions, in this paper, we annually compute direct solar radiation based on monthly average Linke turbidity factor and various tracking modes in two chosen sites in the far north region of Cameroon. Also, a detailed two dimensional numerical heat transfer analysis of a PTC has been performed. The receiver has been divided into many control volumes along his length and each of them is a column consisting of glass, vacuum, absorber and fluid along which mass and energy balance have been applied. Direct solar irradiation, ambient temperature optical and thermal analyses of the collector receiver takes into consideration all modes of heat transfer and the nonlinear algebraic equations were solved simultaneously at each instant during a day of computation using Engineering Equation Solver (EES). To validate the numerical results, the model was compared with experimental data obtained from Sandia National Laboratory (SNL). It has shown a great concordance with a maximum relative error value of 0.35% and thermal efficiency range of systems about 66.67% - 73.2%. It has also been found that the one axis polar East-West and horizontal East-West tracking with 96% and 94% of full tracking mode respectively, were most suitable for a parabolic trough collector throughout the whole year in the two towns considered.
文摘The use of air scrubbers to reduce ammonia (NH<sub>3</sub>) emissions from buildings on pig farms is one of the most promising techniques in the GÖteborg protocol and other European regulations including the Industrial Emission Directive. In France, some air scrubbers are currently used on pig farms, mainly to reduce odours from livestock buildings. However, recent research revealed the production of N<sub>2</sub>O resulting from the treatment of air from pig buildings. In this context, a two-month study was conducted on a pig farm with 750 places for fattening pigs to check the abatement of NH3 emissions and to assess the possible production of N<sub>2</sub>O during treatment of exhausted air from buildings housing fattening pigs by a air scrubber. Concentrations of NH<sub>3</sub> and N<sub>2</sub>O in the inlet and outlet air of the scrubber were continuously monitored using an Innova 1412 infrared analyzer. With the scrubber operating parameters (airflow, design, size), our results confirmed the production of N<sub>2</sub>O in the order of 5% of NH<sub>3</sub>-N reduced. N<sub>2</sub>O was produced by biological nitrification and/or denitrification inside the air scrubber. Statistical analysis (Pearson’s test) showed that the production of N<sub>2</sub>O was strongly influenced by the rate of airflow and the outside temperature. The abatement of NH<sub>3</sub> emissions from the building was only 33%, i.e. much lower than the 70% - 90% usually cited in the literature.
基金the ANRT (Association Nationale de la Recherche et de la Technologie) and the Armor Protéines Company for a grant to AR and for funding
文摘This work presents expeditious synthesis of C-glycoside amphiphiles in aqueous media from unprotected di-or mono-saccharides.A Horner-Wadsworth-Emmons/Michael addition/Barbier allylation sequence led to C-glycosides that exhibit hydrotropic properties.The hydrotropic and solubilizing properties of these homoallylic alcohols including a β-C-glycoside moiety as well as additional β-C-glycosidic ketones with a short(C7) alkyl chain are also described and compared with those of commercial O-glucoside references.
