The 3?Nitro?1,2,4?triazole?5?one(NTO)is a high energy density materials of keen interest for both commercial and scientific worlds owing to its reduced sensitivity,better thermal stability and high performances. It pl...The 3?Nitro?1,2,4?triazole?5?one(NTO)is a high energy density materials of keen interest for both commercial and scientific worlds owing to its reduced sensitivity,better thermal stability and high performances. It plays a significant role to replace the current energetic ingredients. In this review,we summarize various strategies involved in the synthesis of NTO as well as the existing approaches to tailor its particle morphology and sizes. The most prominent properties of NTO,such as insensitivity and performance,which are usually required to produce efficient formulations,have been concisely discussed. In addition,this overview reports on some newer forms of NTO including derivatives and co?crystals available in the literature,which can enhance the NTO features and extend its applications. The advantages and shortcomings of various NTO forms for specific and potential use are also highlighted together with the attempts made to overcome these issues. Therefore,efforts will certainly continue to improve characteristics and performances of NTO either by chemical modification or by co?crystallization in order to produce promising formulations for widespread applications in the near future.展开更多
In this study,the kerogen of oil shale from Moroccan Tarfaya deposits was isolated and the changes in the initial organic matter during the removal of the mineral matrix were examined.Chloroform extraction of the oil ...In this study,the kerogen of oil shale from Moroccan Tarfaya deposits was isolated and the changes in the initial organic matter during the removal of the mineral matrix were examined.Chloroform extraction of the oil shale increases the intensity of the peaks in the X-ray diffractograms.Infrared spectra and X-ray diffractograms reveal the presence of mineral,calcite,quartz,kaolinite,and pyrite in the mineral matrix of the oil shale.Hydrochloric and hydrofluoric acids dissolution do not alter the organic matter.The nonisothermal weight loss measurements indicate that thermal decomposition of the isolated kerogen can be described by first-order reaction.A single kinetic expression is valid over the temperature range of kerogen pyrolysis between 433K and 873K.Furthermore,the results indicate that the removal of mineral matter causes a decrease in the activation energies of the pyrolysis reactions of oil shale.展开更多
Li4Si O4 has been regarded as one of the most promising high-temperature CO2 sorbents.However,for practical applications,its CO2sorption kinetics,cycling stability and sorption properties at lower temperatures or lowe...Li4Si O4 has been regarded as one of the most promising high-temperature CO2 sorbents.However,for practical applications,its CO2sorption kinetics,cycling stability and sorption properties at lower temperatures or lower CO2 concentrations have to be improved.In this contribution,four Li4Si O4 sorbents were synthesized from zeolite precursors MCM-41,MCM-48,TS-1,and ZSM-5.The CO2 uptake,cycling stability and the optimal CO2 sorption conditions were investigated.Among the samples,MCM-41-Li4Si O4 showed the best cycling stability at 650°C,with a stable reversible CO2 uptake of 29.1 wt%under 100 vol%CO2 during 20 cycles.But its sorption kinetics and CO2 uptakes at lower temperatures and lower CO2 concentrations need to be improved.We then demonstrated that the sorption kinetics can be improved by modifying the MCM-41 precursor with metals such as Al,Ti,Ca,and Na.The Na-MCM-41-Li4Si O4 sample exhibited the highest sorption rate,and reached the equilibrium sorption capacity close to the theoretical value of 36.7 wt%within 20 min.In addition,we proved that coating the MCM-41-Li4Si O4with Na2CO3and K2CO3can significantly increase the CO2uptakes at lower temperatures(e.g.550℃)and lower CO2concentrations(10–20 vol%).At 550℃ and under 20 vol%CO2,15 wt%K2CO3-MCM-41-Li4Si O4 and 10 wt%Na2CO3-MCM-41-Li4Si O4 sorbents resulted in a CO2 uptake of 32.2 wt%and 34.7 wt%,respectively,which are much higher than that of MCM-41-Li4Si O4(11.8 wt%).These two sorbents also showed good cycling stability.The promoiting mechasnim by alkali carbonate coating was discussed by a doubleshell model.展开更多
This paper demonstrates the thermal pyrolysis of olive residue,low density polyethylene(LDPE) and olive residue/LDPE mixture in an inert atmosphere of N2 using thermogravimetric analysis(TGA).Measurements were carried...This paper demonstrates the thermal pyrolysis of olive residue,low density polyethylene(LDPE) and olive residue/LDPE mixture in an inert atmosphere of N2 using thermogravimetric analysis(TGA).Measurements were carried out in the temperature range 300K^973K at heating rates of 2K/min,10K/min,20K/min and 50K/min.Based on the results obtained,three temperature regimes were selected for studying the non-isothermal kinetics of olive residue/LDPE mixture.The first two were dominated by the olive residue pyrolysis,while the third was linked to the LDPE pyrolysis,which occurred at much higher temperatures.Discrepancies between the experimental and calculated TG/DTG profiles were considered as a measurement of the extent of interactions occurring on co-pyrolysis.The maximum degradation temperatures of each component in the mixture were higher than those the individual components;thus an increase in thermal stability was expected.The kinetic parameters associated with thermal degradation were determined using Friedman isoconversional method.展开更多
The assessment of the real in-service-time(RIST)and the equivalent in-service-time(EIST)of double base rocket propellants(DBRPs)is of utmost importance for the safe storage and use of weapon systems as well as the eff...The assessment of the real in-service-time(RIST)and the equivalent in-service-time(EIST)of double base rocket propellants(DBRPs)is of utmost importance for the safe storage and use of weapon systems as well as the efficiency of the accelerated aging plans.In this work,four DBRPs with similar chemical composition and different natural aging have been artificially aged at T?338.65 K for 4 months with sampling every 30 days.The unaged and artificially aged samples have been investigated by vacuum stability test(VST)at five isothermal temperatures(T?333.15 K,343.15 K,353.15 K,363.15 K,and 373.15 K).The volume of the evolved gases in VST was found to decrease with natural/artificial aging.Furthermore,the VST data were treated and subjected to principal component analysis(PCA).The results showed excellent discrimination of the DBRP samples according to their stability thermal properties.Most of the variance was described by the first principal component(PC1)whose scores were linearly correlated with the natural aging durations when PCA is applied on VST data obtained at T?363.15 K.In light of the obtained results,a new experimental way for the estimation of the real/equivalent IST was proposed,which takes into account the impact of the natural aging of the sample.The approach predicts successfully the RIST of two similar DBRPs with a relative deviation of less than 2%.At the specific heating temperature T?338.65 K,the developed model provides more conceivable EIST values,with asymptotic behavior against artificial aging duration evolution,thus overcoming some shortcomings of the common generalized van’t Hoff formula(GvH).展开更多
The process of ultrafiltration(UF)of natural seawater often encounters the problems of variation in water quality and coastal blooms.To validate the feasibility of UF in shellfish farms,this study compared the hydraul...The process of ultrafiltration(UF)of natural seawater often encounters the problems of variation in water quality and coastal blooms.To validate the feasibility of UF in shellfish farms,this study compared the hydraulic performance and pollutant removal efficiency of the UF process with those of the commonly used treatments that combine several filtration steps with ultraviolet(UV)disinfection.The comparison was conducted in the cases of natural seawater and a coastal bloom.Given that the UF process encountered the specific type of pollution,this study evaluated the filtration performance of the UF process and the retention of total suspended solids(TSS),bacteria,phytoplankton,and zooplankton.A real coastal bloom was considered in the case study of an experimental shellfish hatchery/nursery in France.The results show that both treatments were able to eliminate approximately 50%of TSS.However,in contrast with UV treatment combined with filtration,the UF process retained total amounts of phytoplankton,zooplankton,and bacteria in the bloom.Although the hydraulic performance of the UF process was impacted by the coastal bloom,the fouling was eliminated through chemical cleaning conducted at a frequency less than once per 12 h.Despite the severe pollution,this study confirmed the pollution resistance and treatment performance of the UF process,indicating that UF has the potential to enhance the biosecurity level.展开更多
This investigation deals with the effects of slip, magnetic field, and non- Newtonian flow parameters on the flow and heat transfer of an incompressible, electrically conducting fourth-grade fluid past an infinite por...This investigation deals with the effects of slip, magnetic field, and non- Newtonian flow parameters on the flow and heat transfer of an incompressible, electrically conducting fourth-grade fluid past an infinite porous plate. The heat transfer analysis is carried out for two heating processes. The system of highly non-linear differential equations is solved by the shooting method with the fourth-order Runge-Kutta method for moderate values of the parameters. The effective Broyden technique is adopted in order to improve the initial guesses and to satisfy the boundary conditions at infinity. An exceptional cross-over is obtained in the velocity profile in the presence of slip. The fourth-grade fluid parameter is found to increase the momentum boundary layer thickness, whereas the slip parameter substantially decreases it. Similarly, the non-Newtonian fluid parameters and the slip have opposite effects on the thermal boundary layer thickness.展开更多
为了研究热塑性聚合物粉末的烧结合并过程,在Frenkel、Eshelby和Pokluda等人模型的基础上建立2D数学模型,同时用尼龙纤维(长度远大于直径,可视为无限长)进行烧结实验,观察其横截面的合并过程。将数学模型预测结果与实验结果以及Constrai...为了研究热塑性聚合物粉末的烧结合并过程,在Frenkel、Eshelby和Pokluda等人模型的基础上建立2D数学模型,同时用尼龙纤维(长度远大于直径,可视为无限长)进行烧结实验,观察其横截面的合并过程。将数学模型预测结果与实验结果以及Constrained Natural Element Method(C-NEM)数值模拟结果进行对比,其结果基本一致,所获得的数学模型和实验结果可为烧结合并过程的数值模拟和理论研究提供依据。展开更多
The integration of additive manufacturing(AM)in design and engineering has prompted a wide spectrum of research efforts,involving topologically optimized solid/lattice structures,multimaterial structures,bioinspired o...The integration of additive manufacturing(AM)in design and engineering has prompted a wide spectrum of research efforts,involving topologically optimized solid/lattice structures,multimaterial structures,bioinspired organic structures,and multiscale structures,to name a few.However,except for obvious cases,very little attention has been given to the design and printing of more complex three-dimensional(3D)hollow structures or folded/creased structures.One of the main reasons is that such complex open or closed 3D cavities and regular/freeform folds generally lead to printing difficulties from support-structure-related issues.To address this barrier,this paper aims to investigate four-dimensional(4D)printing as well as origami-based design as an original research direction to design and build 3D support-free hollow structures.This work consists of describing the rough 3D hollow structures in terms of two-dimensional(2D)printed origami precursor layouts without any support structure.Such origami-based definitions are then embodied with folding functions that can be actuated and fulfilled by 3D printed smart materials.The desired 3D shape is then built once an external stimulus is applied to the active materials,therefore ensuring the transformation of the 2D origami layout to 3D structures.To demonstrate the relevance of the proposal,some illustrative cases are introduced.展开更多
Bimetallic Au_xCu_y/CeO_2（x/y = 3/1,1/1,and 1 /3） catalysts were prepared by direct anion exchange（DAE）,following impregnation（IMP） methods,and used for selective hydrogenation of cinnamaldehyde.The effects of p...Bimetallic Au_xCu_y/CeO_2（x/y = 3/1,1/1,and 1 /3） catalysts were prepared by direct anion exchange（DAE）,following impregnation（IMP） methods,and used for selective hydrogenation of cinnamaldehyde.The effects of pretreatments,such as calcination or reduction on the catalytic activities of these catalysts were investigated.XRD and HRTEM showed that for the reduced catalysts,there is the formation of an Au-Cu alloy.HAADF-STEM displayed that reduction pretreatment leads to a very homogenous distribution of Au and Cu on the external catalyst surface.Reaction parameters,such as CAL concentration,the stirring speed,nature of the solvent influence the catalytic activities.Pretreatments lead to a major effect on CAL conversion and HCAL selectivity.Catalysts Au_xCu_y/CeO_2 pretreated under reduction display higher CAL conversion and HCAL selectivity than that of under calcination mainly due to the synergistic effect resulting in a formation of Au-Cu alloy.展开更多
The aqueous extracts of different parts (old leaves (OL), young leaves (YL), peels (PE) and delipidated seed residues (DS)) of three varieties of papaya are studied. Extraction conditions are optimized: an extraction ...The aqueous extracts of different parts (old leaves (OL), young leaves (YL), peels (PE) and delipidated seed residues (DS)) of three varieties of papaya are studied. Extraction conditions are optimized: an extraction time of 20 minutes, a temperature of 70°C and a plant material/water mixture of 1% give the best yield of polyphenol. The amount of polyphenols, flavonoids, saponins and proanthocyanins of each aqueous extract was investigated. Antioxidant activities are measured using two different methods (DPPH and ABTS). The delipidated seeds (DS) of V1 have the highest total phenolic content (TPC = 72.56 ± 3.16 mg GAE/g) while they have the lowest total flavonoid content (TFC = 0.22 ± 0.01). With regard to saponins, the PE of V3 is much richer in saponins (194.03 ± 15.78 mg AeE/g) than all the other extracts studied. The OL of V2 and PE of V1 contain the most proanthocyanidins with very similar values of 2.51 ± 0.03 mg CE/g and 2.53 ± 0.34 mg CE/g respectively. The study of the antioxidant activities of the extracts showed a correlation between the amount of polyphenols and IC50. DPPH OL and YL V2, which are rich in polyphenols, have the lowest IC50 of 0.072 mg/ml and 0.080 mg/ml respectively, whereas for ABTS we have PE of V1 that is very rich in polyphenols which has the smallest IC50 value of 0.218 mg/ml.展开更多
This paper studied the efficiency of electrocoagulation/electroflotation in removing colour from real textile wastewater by using aluminum and iron electrodes in an innovative pilot external-loop airlift reactor of 15...This paper studied the efficiency of electrocoagulation/electroflotation in removing colour from real textile wastewater by using aluminum and iron electrodes in an innovative pilot external-loop airlift reactor of 150 L. The reactor was designed to operate in batch and continuous modes. The real effluent contained 90% of disperse dye and 10% of reactive dye. A complete flotation of pollutants with acceptable mixing was achieved in this reactor using only the overall liquid recirculation induced by H2 microbubbles. The treatment of these discharges was easier using electrodes of iron rather than aluminum. The optimal initial pH was 10 for both aluminum and iron electrodes. By using iron electrodes, the maximum decolourisation efficiency and COD reduction efficiency reached respectively 96% and 65% for 90 minutes of treatment. Similarly, by using aluminum electrodes, the maximum decolourisation efficiency reached 90%, COD reduction reached 51% for 120 minutes of treatment. In the case of an initial pH slightly different to 10, the required time to reach 90% ranged from double to triple.展开更多
In this paper the influence of sample initial size on their convective drying at 80°C using convective dryer is determined. Results prove that initial size must be taken into account when drying process was estim...In this paper the influence of sample initial size on their convective drying at 80°C using convective dryer is determined. Results prove that initial size must be taken into account when drying process was estimated. This influence is limited by its form of cut. Comparing cubic form and parallelepiped (slice) one;results seem to show that thickness is the most important parameter governing the transfer phenomena during foodstuff convective drying. Three slices with thickness of 0.5 cm and surface area of 17, 82 and 112 cm2 respectively, dry better than cubic sample with a = 1 cm or a = 2 cm of arrest and having respectively 6 and 24 cm2 of surface area. All things seem to show that initial surface is not only the essential parameter;but also the thickness of the sample must be taken into account. Indeed, all of the samples with equal thickness (0.5 cm) and different exchange surfaces dry at the same time, about 210 min, comparing with cubic form 1 cm of arrest and 6 cm2 of surface and drying time of 230 min. A new parameter noted Dc called characteristic diameter is so considered to bridge the gaps. It is defined to be the diameter of the biggest sphere we can cut into a sample. This parameter is independent of form of the sample, and time increase with characteristic diameter increasing.展开更多
Modeling experimental design was used to study the main effects and the interaction effects between operational parameters in the photocatalytic degradation of pesticide methomyl. The important parameters which affect...Modeling experimental design was used to study the main effects and the interaction effects between operational parameters in the photocatalytic degradation of pesticide methomyl. The important parameters which affect the removal efficiency of methomyl such as concentration of Fe(NO3)3, concentration of H2O2, initial concentration of the pesticide and pH. The parameters were coded as x1, x2, x3 and x4, consecutively, and were investigated at two levels (–1 and +1). The effects of individual variables and their interaction effects for dependent variables, namely, photocatalytic degradation efficiency (%) were determined. From the statistical analysis, the most effective parameters in the photocatalytic degradation efficiency were initial concentrations of the methomyl and Fe(NO3)3. The interaction between initial concentration of the pesticide and Fe(NO3)3 was the most influencing interaction. The optimum conditions that were obtained for the photocatalytic degradation of methomyl were: minimum quantity of contaminant: 6 × 10–5 mol.L–1, maximum quantity of Fe(NO3)3: 5 × 10–4 mol.L-1, initial pH of the solution: 3 and maximum quantity H2O2: 10–2 mol.L–1.展开更多
The reinforcing impact of Lignocellulosic micro and nanofibrillated cellulose(L-MNFCs)obtained from Eucalyp-tus Globulus bark in Urea-Formaldehyde UF adhesive was tested.L-MNFCs were prepared by an environmentally fri...The reinforcing impact of Lignocellulosic micro and nanofibrillated cellulose(L-MNFCs)obtained from Eucalyp-tus Globulus bark in Urea-Formaldehyde UF adhesive was tested.L-MNFCs were prepared by an environmentally friendly,low-cost process using a combination process involving steam explosion followed by refining and ultra-fine grinding.Obtained L-MNFCs showed a web-like morphology with some aggregates and lignin nanodroplets.They present a mixture of residual fibers and fine elements with a width varying between 5 nm to 20μm,respec-tively.The effects of the addition of low amounts of L-MNFCs(1%wt.)on the properties of three different adhe-sives(Urea-Formaldehyde UF,Phenol-Formaldehyde PF,and Tannin-Hexamine TH)were studied by the evolution of the pH,the viscosity,and the mechanical properties.Results showed that the viscosity of PF and UF adhesives increased with the addition of L-MNFCs,unlike TH.Meanwhile,the addition led to better mechan-ical behavior for the three adhesives.Particleboards were then prepared using modified UF with L-MNFCs and tested.Results showed that an amount of 1%wt.of L-MNFCs was sufficient to increase the internal bonding by≈67%,the modulus of elasticity by≈43%,and the modulus of rupture by≈29%.展开更多
Modelling of carob batch fermentation is established basing on mass transfer balances. The modelling treats the reaction kinetics of substrate （S）, the micro-organisms （X） and the ethanol （E）. Nine models are ta...Modelling of carob batch fermentation is established basing on mass transfer balances. The modelling treats the reaction kinetics of substrate （S）, the micro-organisms （X） and the ethanol （E）. Nine models are taken from the literature to describe specific organism growth rate and specific ethanol development rate. These models treat all types of fermentation. The Phisalapbong et al. model and the Ghose and Tyagi model show the best fit of the experimental data. This affirms that the batch fermentation of carob is conducted with substrate and/or ethanol inhibition. Some simulations and relationships （X = f（S）, E = f（S）） are obtained from the Phisalaphong et al. model. Those simulations show a lot of important and useful results of carob batch fermentation process.展开更多
文摘The 3?Nitro?1,2,4?triazole?5?one(NTO)is a high energy density materials of keen interest for both commercial and scientific worlds owing to its reduced sensitivity,better thermal stability and high performances. It plays a significant role to replace the current energetic ingredients. In this review,we summarize various strategies involved in the synthesis of NTO as well as the existing approaches to tailor its particle morphology and sizes. The most prominent properties of NTO,such as insensitivity and performance,which are usually required to produce efficient formulations,have been concisely discussed. In addition,this overview reports on some newer forms of NTO including derivatives and co?crystals available in the literature,which can enhance the NTO features and extend its applications. The advantages and shortcomings of various NTO forms for specific and potential use are also highlighted together with the attempts made to overcome these issues. Therefore,efforts will certainly continue to improve characteristics and performances of NTO either by chemical modification or by co?crystallization in order to produce promising formulations for widespread applications in the near future.
文摘In this study,the kerogen of oil shale from Moroccan Tarfaya deposits was isolated and the changes in the initial organic matter during the removal of the mineral matrix were examined.Chloroform extraction of the oil shale increases the intensity of the peaks in the X-ray diffractograms.Infrared spectra and X-ray diffractograms reveal the presence of mineral,calcite,quartz,kaolinite,and pyrite in the mineral matrix of the oil shale.Hydrochloric and hydrofluoric acids dissolution do not alter the organic matter.The nonisothermal weight loss measurements indicate that thermal decomposition of the isolated kerogen can be described by first-order reaction.A single kinetic expression is valid over the temperature range of kerogen pyrolysis between 433K and 873K.Furthermore,the results indicate that the removal of mineral matter causes a decrease in the activation energies of the pyrolysis reactions of oil shale.
基金supported by the National Natural Science Foundation of China (51622801, 51572029)Beijing Excellent Young Scholar (2015000026833ZK11)the Beijing Natural Science Foundation (2184114)
文摘Li4Si O4 has been regarded as one of the most promising high-temperature CO2 sorbents.However,for practical applications,its CO2sorption kinetics,cycling stability and sorption properties at lower temperatures or lower CO2 concentrations have to be improved.In this contribution,four Li4Si O4 sorbents were synthesized from zeolite precursors MCM-41,MCM-48,TS-1,and ZSM-5.The CO2 uptake,cycling stability and the optimal CO2 sorption conditions were investigated.Among the samples,MCM-41-Li4Si O4 showed the best cycling stability at 650°C,with a stable reversible CO2 uptake of 29.1 wt%under 100 vol%CO2 during 20 cycles.But its sorption kinetics and CO2 uptakes at lower temperatures and lower CO2 concentrations need to be improved.We then demonstrated that the sorption kinetics can be improved by modifying the MCM-41 precursor with metals such as Al,Ti,Ca,and Na.The Na-MCM-41-Li4Si O4 sample exhibited the highest sorption rate,and reached the equilibrium sorption capacity close to the theoretical value of 36.7 wt%within 20 min.In addition,we proved that coating the MCM-41-Li4Si O4with Na2CO3and K2CO3can significantly increase the CO2uptakes at lower temperatures(e.g.550℃)and lower CO2concentrations(10–20 vol%).At 550℃ and under 20 vol%CO2,15 wt%K2CO3-MCM-41-Li4Si O4 and 10 wt%Na2CO3-MCM-41-Li4Si O4 sorbents resulted in a CO2 uptake of 32.2 wt%and 34.7 wt%,respectively,which are much higher than that of MCM-41-Li4Si O4(11.8 wt%).These two sorbents also showed good cycling stability.The promoiting mechasnim by alkali carbonate coating was discussed by a doubleshell model.
文摘This paper demonstrates the thermal pyrolysis of olive residue,low density polyethylene(LDPE) and olive residue/LDPE mixture in an inert atmosphere of N2 using thermogravimetric analysis(TGA).Measurements were carried out in the temperature range 300K^973K at heating rates of 2K/min,10K/min,20K/min and 50K/min.Based on the results obtained,three temperature regimes were selected for studying the non-isothermal kinetics of olive residue/LDPE mixture.The first two were dominated by the olive residue pyrolysis,while the third was linked to the LDPE pyrolysis,which occurred at much higher temperatures.Discrepancies between the experimental and calculated TG/DTG profiles were considered as a measurement of the extent of interactions occurring on co-pyrolysis.The maximum degradation temperatures of each component in the mixture were higher than those the individual components;thus an increase in thermal stability was expected.The kinetic parameters associated with thermal degradation were determined using Friedman isoconversional method.
文摘The assessment of the real in-service-time(RIST)and the equivalent in-service-time(EIST)of double base rocket propellants(DBRPs)is of utmost importance for the safe storage and use of weapon systems as well as the efficiency of the accelerated aging plans.In this work,four DBRPs with similar chemical composition and different natural aging have been artificially aged at T?338.65 K for 4 months with sampling every 30 days.The unaged and artificially aged samples have been investigated by vacuum stability test(VST)at five isothermal temperatures(T?333.15 K,343.15 K,353.15 K,363.15 K,and 373.15 K).The volume of the evolved gases in VST was found to decrease with natural/artificial aging.Furthermore,the VST data were treated and subjected to principal component analysis(PCA).The results showed excellent discrimination of the DBRP samples according to their stability thermal properties.Most of the variance was described by the first principal component(PC1)whose scores were linearly correlated with the natural aging durations when PCA is applied on VST data obtained at T?363.15 K.In light of the obtained results,a new experimental way for the estimation of the real/equivalent IST was proposed,which takes into account the impact of the natural aging of the sample.The approach predicts successfully the RIST of two similar DBRPs with a relative deviation of less than 2%.At the specific heating temperature T?338.65 K,the developed model provides more conceivable EIST values,with asymptotic behavior against artificial aging duration evolution,thus overcoming some shortcomings of the common generalized van’t Hoff formula(GvH).
基金This work was supported by Fonds Europeen Pour les Affaires Maritimes et la P^eche(FEAMP)(Grant No.R FEA 4700 16FA 1000001).
文摘The process of ultrafiltration(UF)of natural seawater often encounters the problems of variation in water quality and coastal blooms.To validate the feasibility of UF in shellfish farms,this study compared the hydraulic performance and pollutant removal efficiency of the UF process with those of the commonly used treatments that combine several filtration steps with ultraviolet(UV)disinfection.The comparison was conducted in the cases of natural seawater and a coastal bloom.Given that the UF process encountered the specific type of pollution,this study evaluated the filtration performance of the UF process and the retention of total suspended solids(TSS),bacteria,phytoplankton,and zooplankton.A real coastal bloom was considered in the case study of an experimental shellfish hatchery/nursery in France.The results show that both treatments were able to eliminate approximately 50%of TSS.However,in contrast with UV treatment combined with filtration,the UF process retained total amounts of phytoplankton,zooplankton,and bacteria in the bloom.Although the hydraulic performance of the UF process was impacted by the coastal bloom,the fouling was eliminated through chemical cleaning conducted at a frequency less than once per 12 h.Despite the severe pollution,this study confirmed the pollution resistance and treatment performance of the UF process,indicating that UF has the potential to enhance the biosecurity level.
文摘This investigation deals with the effects of slip, magnetic field, and non- Newtonian flow parameters on the flow and heat transfer of an incompressible, electrically conducting fourth-grade fluid past an infinite porous plate. The heat transfer analysis is carried out for two heating processes. The system of highly non-linear differential equations is solved by the shooting method with the fourth-order Runge-Kutta method for moderate values of the parameters. The effective Broyden technique is adopted in order to improve the initial guesses and to satisfy the boundary conditions at infinity. An exceptional cross-over is obtained in the velocity profile in the presence of slip. The fourth-grade fluid parameter is found to increase the momentum boundary layer thickness, whereas the slip parameter substantially decreases it. Similarly, the non-Newtonian fluid parameters and the slip have opposite effects on the thermal boundary layer thickness.
文摘为了研究热塑性聚合物粉末的烧结合并过程,在Frenkel、Eshelby和Pokluda等人模型的基础上建立2D数学模型,同时用尼龙纤维(长度远大于直径,可视为无限长)进行烧结实验,观察其横截面的合并过程。将数学模型预测结果与实验结果以及Constrained Natural Element Method(C-NEM)数值模拟结果进行对比,其结果基本一致,所获得的数学模型和实验结果可为烧结合并过程的数值模拟和理论研究提供依据。
基金the Ministère de l’Enseignement Supérieur et de la Recherche, the French ‘Investissements d’Avenir’ program, project ISITE-BFC (contract ANR-15-IDEX-0003)China Scholarship Council as the main financial supports of this research program
文摘The integration of additive manufacturing(AM)in design and engineering has prompted a wide spectrum of research efforts,involving topologically optimized solid/lattice structures,multimaterial structures,bioinspired organic structures,and multiscale structures,to name a few.However,except for obvious cases,very little attention has been given to the design and printing of more complex three-dimensional(3D)hollow structures or folded/creased structures.One of the main reasons is that such complex open or closed 3D cavities and regular/freeform folds generally lead to printing difficulties from support-structure-related issues.To address this barrier,this paper aims to investigate four-dimensional(4D)printing as well as origami-based design as an original research direction to design and build 3D support-free hollow structures.This work consists of describing the rough 3D hollow structures in terms of two-dimensional(2D)printed origami precursor layouts without any support structure.Such origami-based definitions are then embodied with folding functions that can be actuated and fulfilled by 3D printed smart materials.The desired 3D shape is then built once an external stimulus is applied to the active materials,therefore ensuring the transformation of the 2D origami layout to 3D structures.To demonstrate the relevance of the proposal,some illustrative cases are introduced.
基金the Chinese Scholarship Council (CSC), French Eiffel Scholarship for financial supports of Xuemei Liaothe financial supported by the Open Research Subject of key laboratory (Research Base) of Grain and Oil Engineering and food safety (No. szjj2015-006)Agricultural and Forestry Talents in Food quality and safety, Key Research Fund of Xihua University (No. Z1520527)
文摘Bimetallic Au_xCu_y/CeO_2（x/y = 3/1,1/1,and 1 /3） catalysts were prepared by direct anion exchange（DAE）,following impregnation（IMP） methods,and used for selective hydrogenation of cinnamaldehyde.The effects of pretreatments,such as calcination or reduction on the catalytic activities of these catalysts were investigated.XRD and HRTEM showed that for the reduced catalysts,there is the formation of an Au-Cu alloy.HAADF-STEM displayed that reduction pretreatment leads to a very homogenous distribution of Au and Cu on the external catalyst surface.Reaction parameters,such as CAL concentration,the stirring speed,nature of the solvent influence the catalytic activities.Pretreatments lead to a major effect on CAL conversion and HCAL selectivity.Catalysts Au_xCu_y/CeO_2 pretreated under reduction display higher CAL conversion and HCAL selectivity than that of under calcination mainly due to the synergistic effect resulting in a formation of Au-Cu alloy.
文摘The aqueous extracts of different parts (old leaves (OL), young leaves (YL), peels (PE) and delipidated seed residues (DS)) of three varieties of papaya are studied. Extraction conditions are optimized: an extraction time of 20 minutes, a temperature of 70°C and a plant material/water mixture of 1% give the best yield of polyphenol. The amount of polyphenols, flavonoids, saponins and proanthocyanins of each aqueous extract was investigated. Antioxidant activities are measured using two different methods (DPPH and ABTS). The delipidated seeds (DS) of V1 have the highest total phenolic content (TPC = 72.56 ± 3.16 mg GAE/g) while they have the lowest total flavonoid content (TFC = 0.22 ± 0.01). With regard to saponins, the PE of V3 is much richer in saponins (194.03 ± 15.78 mg AeE/g) than all the other extracts studied. The OL of V2 and PE of V1 contain the most proanthocyanidins with very similar values of 2.51 ± 0.03 mg CE/g and 2.53 ± 0.34 mg CE/g respectively. The study of the antioxidant activities of the extracts showed a correlation between the amount of polyphenols and IC50. DPPH OL and YL V2, which are rich in polyphenols, have the lowest IC50 of 0.072 mg/ml and 0.080 mg/ml respectively, whereas for ABTS we have PE of V1 that is very rich in polyphenols which has the smallest IC50 value of 0.218 mg/ml.
文摘This paper studied the efficiency of electrocoagulation/electroflotation in removing colour from real textile wastewater by using aluminum and iron electrodes in an innovative pilot external-loop airlift reactor of 150 L. The reactor was designed to operate in batch and continuous modes. The real effluent contained 90% of disperse dye and 10% of reactive dye. A complete flotation of pollutants with acceptable mixing was achieved in this reactor using only the overall liquid recirculation induced by H2 microbubbles. The treatment of these discharges was easier using electrodes of iron rather than aluminum. The optimal initial pH was 10 for both aluminum and iron electrodes. By using iron electrodes, the maximum decolourisation efficiency and COD reduction efficiency reached respectively 96% and 65% for 90 minutes of treatment. Similarly, by using aluminum electrodes, the maximum decolourisation efficiency reached 90%, COD reduction reached 51% for 120 minutes of treatment. In the case of an initial pH slightly different to 10, the required time to reach 90% ranged from double to triple.
文摘In this paper the influence of sample initial size on their convective drying at 80°C using convective dryer is determined. Results prove that initial size must be taken into account when drying process was estimated. This influence is limited by its form of cut. Comparing cubic form and parallelepiped (slice) one;results seem to show that thickness is the most important parameter governing the transfer phenomena during foodstuff convective drying. Three slices with thickness of 0.5 cm and surface area of 17, 82 and 112 cm2 respectively, dry better than cubic sample with a = 1 cm or a = 2 cm of arrest and having respectively 6 and 24 cm2 of surface area. All things seem to show that initial surface is not only the essential parameter;but also the thickness of the sample must be taken into account. Indeed, all of the samples with equal thickness (0.5 cm) and different exchange surfaces dry at the same time, about 210 min, comparing with cubic form 1 cm of arrest and 6 cm2 of surface and drying time of 230 min. A new parameter noted Dc called characteristic diameter is so considered to bridge the gaps. It is defined to be the diameter of the biggest sphere we can cut into a sample. This parameter is independent of form of the sample, and time increase with characteristic diameter increasing.
文摘Modeling experimental design was used to study the main effects and the interaction effects between operational parameters in the photocatalytic degradation of pesticide methomyl. The important parameters which affect the removal efficiency of methomyl such as concentration of Fe(NO3)3, concentration of H2O2, initial concentration of the pesticide and pH. The parameters were coded as x1, x2, x3 and x4, consecutively, and were investigated at two levels (–1 and +1). The effects of individual variables and their interaction effects for dependent variables, namely, photocatalytic degradation efficiency (%) were determined. From the statistical analysis, the most effective parameters in the photocatalytic degradation efficiency were initial concentrations of the methomyl and Fe(NO3)3. The interaction between initial concentration of the pesticide and Fe(NO3)3 was the most influencing interaction. The optimum conditions that were obtained for the photocatalytic degradation of methomyl were: minimum quantity of contaminant: 6 × 10–5 mol.L–1, maximum quantity of Fe(NO3)3: 5 × 10–4 mol.L-1, initial pH of the solution: 3 and maximum quantity H2O2: 10–2 mol.L–1.
基金The authors gratefully acknowledge the financial support of Labex Tec21 and Labex Arbre for the thesis funding.This work was also supported by the Franco-Chilean EcosSud Collaborative Program C18E05,ANID PIA/Apoyo CCTE AFB170007 of Universidad de Concepcion.
文摘The reinforcing impact of Lignocellulosic micro and nanofibrillated cellulose(L-MNFCs)obtained from Eucalyp-tus Globulus bark in Urea-Formaldehyde UF adhesive was tested.L-MNFCs were prepared by an environmentally friendly,low-cost process using a combination process involving steam explosion followed by refining and ultra-fine grinding.Obtained L-MNFCs showed a web-like morphology with some aggregates and lignin nanodroplets.They present a mixture of residual fibers and fine elements with a width varying between 5 nm to 20μm,respec-tively.The effects of the addition of low amounts of L-MNFCs(1%wt.)on the properties of three different adhe-sives(Urea-Formaldehyde UF,Phenol-Formaldehyde PF,and Tannin-Hexamine TH)were studied by the evolution of the pH,the viscosity,and the mechanical properties.Results showed that the viscosity of PF and UF adhesives increased with the addition of L-MNFCs,unlike TH.Meanwhile,the addition led to better mechan-ical behavior for the three adhesives.Particleboards were then prepared using modified UF with L-MNFCs and tested.Results showed that an amount of 1%wt.of L-MNFCs was sufficient to increase the internal bonding by≈67%,the modulus of elasticity by≈43%,and the modulus of rupture by≈29%.
文摘Modelling of carob batch fermentation is established basing on mass transfer balances. The modelling treats the reaction kinetics of substrate （S）, the micro-organisms （X） and the ethanol （E）. Nine models are taken from the literature to describe specific organism growth rate and specific ethanol development rate. These models treat all types of fermentation. The Phisalapbong et al. model and the Ghose and Tyagi model show the best fit of the experimental data. This affirms that the batch fermentation of carob is conducted with substrate and/or ethanol inhibition. Some simulations and relationships （X = f（S）, E = f（S）） are obtained from the Phisalaphong et al. model. Those simulations show a lot of important and useful results of carob batch fermentation process.
