Background:Acute cholangitis is an infection due to the bile duct obstruction.Despite progress in treat-ment,acute cholangitis remains potentially fatal.Early diagnosis and treatment improve the patient out-comes.The ...Background:Acute cholangitis is an infection due to the bile duct obstruction.Despite progress in treat-ment,acute cholangitis remains potentially fatal.Early diagnosis and treatment improve the patient out-comes.The present study aimed to identify clinical and biological factors at admission associated with 30-day mortality in acute cholangitis,to build an efficient prognostic score based on these parameters and to study the performances of this new score.Methods:We enrolled all adult patients consecutively hospitalized for acute cholangitis between January 2017 and December 2021.We developed a score system named ProChol using variables significantly asso-ciated with 30-day mortality in multivariate logistic analysis and simplified this system(named sProChol)based on a simple points-based approach.Results:In total,528 patients were included,with an average age of 77±13 years,a male predominance(54.2%)and a majority of lithiasis etiology(66.5%).Mortality in 30 days was 11.9%.In multivariate logis-tic analysis,tumor etiology[adjusted odds ratio(aOR)=15.43,95%confidence interval(CI):5.90-40.40],stent obstruction(aOR=5.12,95%CI:2.02-12.99),hypoalbuminemia(aOR=3.50,95%CI:1.25-9.81),renal failure(aOR=6.51,95%CI:2.62-16.18),oxygen therapy(aOR=4.63,95%CI:1.02-20.92)and cu-rative anticoagulation(aOR=2.60,95%CI:1.23-5.52)were independently associated with the 30-day mortality while fever was a protective factor(aOR=0.37,95%CI:0.16-0.84).ProChol score using these 7 parameters and sProChol using the 3 robust factors(etiology,renal failure and anticoagulation)presented respectively an area under receiver operating characteristic(ROC)curves(AUC)of 0.81 and 0.77,higher than Tokyo(AUC=0.72)and Gravito-Soares et al.score(AUC=0.71).Patients with sProChol≥4 had a significantly higher risk of transfer to intensive care unit(13.3%vs.5.1%;P<0.001)and longer length of stay(P=0.0006).Conclusions:ProChol and sProChol constructed from simple clinico-biological parameters at admission,present interesting performances in predicting the 30-day mortality in acute cholangitis.展开更多
Gallstone pancreatitis is the leading cause of acute pancreatitis,accounting for more than 40%of cases.Etiological treatment is a critical issue in acute biliary pancreatitis as it helps reduce the risk of recurrence....Gallstone pancreatitis is the leading cause of acute pancreatitis,accounting for more than 40%of cases.Etiological treatment is a critical issue in acute biliary pancreatitis as it helps reduce the risk of recurrence.Patients who have ex-perienced a complicated form of biliary disease are at high risk for recurrent episodes,and the severity of these new episodes can be unpredictable.In recent years,the role and timing of cholecystectomy and endoscopic retrograde cholan-giopancreatography(ERCP),which are the main therapeutic interventions in the etiological treatment,have been considerably clarified.This review aims to detail the different aspects of the etiological treatment of acute biliary pancreatitis.Currently,it is established that cholecystectomy should be performed early during the initial hospitalization in cases of non-severe acute pancreatitis.However,the optimal timing of this procedure in severe acute pancreatitis remains a subject of debate.Emergency ERCP is no longer indicated for acute biliary pancreatitis,except in cases of associated acute cholangitis.ERCP can be useful for the management of persistent bile duct stones.Finally,the role of interval sphincterotomy in frail or elderly patients or to reduce the risk of re-currence in those awaiting cholecystectomy in cases of severe acute pancreatitis remains to be fully established.展开更多
With the increasing railway vehicle speed, pantograph--catenary （PAC） system has become an important part as its incidents still stand among the prin- cipal causes of railway traffic interruption. Indeed, when a rai...With the increasing railway vehicle speed, pantograph--catenary （PAC） system has become an important part as its incidents still stand among the prin- cipal causes of railway traffic interruption. Indeed, when a rail vehicle moves, the pantograph should constantly press against the underside of the catenary. Nonetheless, it is difficult to get around the complexity of the physical interaction between the pantograph and the contact wire, which could deteriorate the quality of the electricity transfer. Thus, PAC system performances could dramati- cally be reduced because of bad current collection. Therefore, in this paper, we present an output feedback solution in order to design an active control of PAC system. The proposed solution is based on the backstepping control and an adaptive observer that estimates both the （unknown） catenary parameters and the system state. All synthesis steps are given and the closed-loop analysis shows asymptotic tracking behavior regardless of the time-vary- ing catenary stiffness. Furthermore, a numerical example shows that the PAC contact can be regulated with desired effect.展开更多
As an effective non-petroleum based process for producing light olefins, the methanol-to-olefin(MTO) route has become an indispensable alternative to the industrial production of light olefins. The silicoaluminophosph...As an effective non-petroleum based process for producing light olefins, the methanol-to-olefin(MTO) route has become an indispensable alternative to the industrial production of light olefins. The silicoaluminophosphate SAPO-34 zeolite(CHA-type structure) has proven to be an efficient industrial catalyst for the production of ethylene and propylene by the MTO reaction. However, the inherent structure and related diffusion limitations of SAPO-34 limit the mass transport and thus cause rapid deactivation of the catalyst. Fabrication of hierarchical SAPO-34 zeolite is one of the most effective strategies to address the intrinsic diffusion limitation. As simple, inexpensive, and efficient approach, the post-synthetic route has attracted considerable attention and widely used to introduce secondary meso-/macropores into the microporous SAPO-34 material. Significant effort has been dedicated to the development of post-synthesis strategies to prepare hierarchical SAPO-34 zeolite, thereby enhancing its catalytic performance in the MTO process. This mini-review addresses the post-synthesis preparation of hierarchical SAPO-34 catalysts and their MTO performance. Furthermore, some current problems and prospects of the post-synthesis route to hierarchical SAPO-34 catalysts are also revised. We expect this minireview to inspire the more efficient preparation of hierarchical SAPO-34 catalysts for the MTO process.展开更多
Synthesis of superheavy elements beyond oganesson is facing new challenges as new target–projectile combinations are necessary. Guidance from models is thus expected for future experiments. However, hindered fusion m...Synthesis of superheavy elements beyond oganesson is facing new challenges as new target–projectile combinations are necessary. Guidance from models is thus expected for future experiments. However, hindered fusion models are not well established and predictions in the fission barriers span few MeVs. Consequently, predictions are not reliable. Strategies to constrain both fusion hindrance and fission barriers are necessary to improve the predictive power of the models. But, there is no hope to get an accuracy better than one order of magnitude in fusion–evaporation reactions leading to superheavy elements synthesis.展开更多
Brain-derived neurotrophic factor(BDNF)is one of the neurotrophins,a specific polypeptide growth factor,which plays a crucial role in the proliferation,differentiation,survival,and death of neurons and non-neuronal ce...Brain-derived neurotrophic factor(BDNF)is one of the neurotrophins,a specific polypeptide growth factor,which plays a crucial role in the proliferation,differentiation,survival,and death of neurons and non-neuronal cells.It is not only essential to maintain the balance between death on one side and survival of neurons on the other,but also it mediates additional higher-order activities such as learning,memory,and behavior.It is initially synthesized as a precursor protein,proBDNF,that can be secreted as it is or it can be cleaved intracellularly by furin and proconvertases,or extracellularly by extracellular proteases such as matrix metalloprotease-9 and matrix metalloprotease-2,or plasmin to give mature BDNF.展开更多
Particulate matter in ambient air constitutes a complex mixture of fine and ultrafine particles composed of various chemical compounds including metals, ions, and organics. A multidisciplinary approach was developed b...Particulate matter in ambient air constitutes a complex mixture of fine and ultrafine particles composed of various chemical compounds including metals, ions, and organics. A multidisciplinary approach was developed by studying physico-chemical characteristics and mechanisms involved in the toxicity of particulate atmospheric pollution. PM0.3-2.s and PM2.5 including ultrafine particles were sampled in Dunkerque, a French industrialized seaside city. PM samples were characterized from a chemical and toxicological point of view. Physico-chemical characterization evidenced that PM2.5 comes from several sources： natural ones, such as soil resuspension and marine sea-salt emissions, as well as anthropogenic ones, such as shipping traffic, road traffic, and industrial activities. Human BEAS-2B tung cells were exposed to PM0.3-2.5, or to the Extractable Organic Matter （EOM） of PM0.3-2.5 and PM2.s. These exposures induced several mechanisms of action implied in the genotoxicity, such as oxidative DNA adducts and DNA Damage Response. The toxicity of PM-EOM was higher for the sample including the ultrafine fraction （PM2.5） containing also higher concentrations of polycyclic aromatic hydrocarbons. These results evidenced the major role of organic compounds in the toxicity of PM.展开更多
The first case of Prinzmetal angina was described in 1959 by Prinzmetal, et al. Since this description, several triggering factors have been associated with vasospastic angina （VA） and included： illicit drugs such ...The first case of Prinzmetal angina was described in 1959 by Prinzmetal, et al. Since this description, several triggering factors have been associated with vasospastic angina （VA） and included： illicit drugs such as cocaine, amphetamine or marijuana, but also bitter-orange, alcohol, butane, chemotherapy drugs, over-the-counter medication and different antibiotics. Smoking is also a major risk factor for developing VA.t21 Thus, except for smoking, many of conventional atherosclerosis risk factors do not appear to be applicable to VA.t21 However, vasospastic angina can also occur without any triggering factor.展开更多
CO2 adsorption on the surface of hydrotalcite-derived mixed oxide catalysts was investigated under low pressure glow discharge plasma in opercindo conditions via FT-IR spectroscopy.Nickel catalysts were promoted with ...CO2 adsorption on the surface of hydrotalcite-derived mixed oxide catalysts was investigated under low pressure glow discharge plasma in opercindo conditions via FT-IR spectroscopy.Nickel catalysts were promoted with various transition metal species(Ce,Fe,La,Zr)to influence their physico-chemical properties.Fe and Zr species were successfully incorporated into hydrotalcite brucite layers.After calcination formed a single phase with Ni(Mg,A1)O mixed oxide,while La and Ce species formed separate phases.This had a consequence in the distribution of surface basic sites as well as in the affinity to CO produced upon CO2 dissociation in plasma.Plasma treatment activated the surface of prepared materials and changed their properties via the generation of strong basic sites associated with low coordinated surface oxygen anions.Moreover,the CO2 adsorption capacity of prepared materials increased after plasma treatment.展开更多
The present study analyses the spatio-temporal variability of the macrozoobenthos from the intertidal zone of the Kneiss Islands (Gulf of Gabès, Tunisia). Samples were collected once from 34 stations, while seaso...The present study analyses the spatio-temporal variability of the macrozoobenthos from the intertidal zone of the Kneiss Islands (Gulf of Gabès, Tunisia). Samples were collected once from 34 stations, while seasonal variations were studied by sampling four times at 12 stations over the period 2013-2014. A total of 159 macrobenthos taxa associated with intertidal Zostera noltei beds are identified from the 34 stations, with a taxonomic dominance of crustaceans (32%), molluscs (29%) and annelids (27%). Abundance varies from 9244 to 36,844 ind·m<sup>-2</sup> with a mean value of 14,346 ind·m<sup>-2</sup>. Analysis of the trophic structure shows that the majority of stations are strongly represented by carnivores (41%), followed by the non-selective deposit feeders (16%). Cluster analysis and multidimensional scaling allow identification of three main benthic assemblages based on species abundance, corresponding to different sediment types and organic matter contents. The seasonal variability in abundance, diversity and community structure is mainly due to spring and summer recruitment. The biotic indices (i.e. AMBI, BO2A and BENTIX) show that the intertidal area of Kneiss Islands exhibits a good ecological status.展开更多
Zeolites and zeo-type materials with nanosized dimensions are of great practical interest owing to their favorable transport properties,faster adsorption kinetics,and large external surface area.This mini-review prese...Zeolites and zeo-type materials with nanosized dimensions are of great practical interest owing to their favorable transport properties,faster adsorption kinetics,and large external surface area.This mini-review presents recent developments in the organic template-free synthesis of nanosized zeolites and related materials.The advantages and challenges of these methods are addressed with particular attention to the green synthesis of nanozeolites.展开更多
Ultrafine particles represent a growing concern in the public health community but their precise role in many illnesses is still unknown. This lack of knowledge is related to the experimental difficulty in linking the...Ultrafine particles represent a growing concern in the public health community but their precise role in many illnesses is still unknown. This lack of knowledge is related to the experimental difficulty in linking their biological effects to their multiple properties, which are important determinants of toxicity. Our aim is to propose an interdisciplinary approach to study fine(FP) and ultrafine(UFP) particles, generated in a controlled manner using a mini CAST(Combustion Aerosol Standard) soot generator used with two different operating conditions(CAST1 and CAST3). The chemical characterization was performed by an untargeted analysis using ultra-high resolution mass spectrometry. In conjunction with this approach, subsequent analysis by gas chromatography–mass spectrometry(GC–MS) was performed to identify polycyclic aromatic hydrocarbons(PAH). CAST1 enabled the generation of FP with a predominance of small PAH molecules, and CAST3 enabled the generation of UFP, which presented higher numbers of carbon atoms corresponding to larger PAH molecules. Healthy normal human bronchial epithelial(NHBE) cells differentiated at the air-liquid interface(ALI) were directly exposed to these freshly emitted FP and UFP. Expression of MUC5AC, FOXJ1, OCLN and ZOI as well as microscopic observation confirmed the ciliated pseudostratified epithelial phenotype. Study of the mass deposition efficiency revealed a difference between the two operating conditions, probably due to the morphological differences between the two categories of particles. We demonstrated that only NHBE cells exposed to CAST3 particles induced upregulation in the gene expression of IL-8 and NQO1. This approach offers new perspectives to study FP and UFP with stable and controlled properties.展开更多
The integrated molar absorption coefficients for ν(OH) (3655 cm-1), δ(OH) (Q branch at 1176 cm-1 or whole bands), [ν(CCring) + δ(OH)] (Q branch at 1344 cm-1 or whole bands) and γ(CH) (752 cm-1) were determined at...The integrated molar absorption coefficients for ν(OH) (3655 cm-1), δ(OH) (Q branch at 1176 cm-1 or whole bands), [ν(CCring) + δ(OH)] (Q branch at 1344 cm-1 or whole bands) and γ(CH) (752 cm-1) were determined at 342 K, by recording infrared spectra of pure gaseous phenol at different partial pressure (from 0 to 33 Pa). The integrated molar absorption coefficients (ε) values were obtained with a good reproducibility and the relative uncertainty on the given values is below 2%. The influence of water on the integrated molar absorption coefficients of phenol has been investigated in a large range of nwater/nphenol values (from 0.5 to 6.1 and from 44 to 94) using distinct setups. The infrared spectra of a gas mixture containing a constant amount of phenol and different amount of water were recorded (closed cell) whereas in dynamic condition (under flow) the water partial pressure was kept constant at 1.3 kPa and the phenol partial pressure was increased from 0 to 30 Pa. It is here demonstrated that, at 342 or 355 K, the presence of water does not affect the epsilon values of δ(OH) and [ν(CCring) + δ(OH)] bands.展开更多
Based on experimental test results,flax fiber reinforced polymer composites are characterized by nonlinear visco-elastoplastic behavior.The aim of this work is to model the quasi-unidirectional flax fiber reinforced c...Based on experimental test results,flax fiber reinforced polymer composites are characterized by nonlinear visco-elastoplastic behavior.The aim of this work is to model the quasi-unidirectional flax fiber reinforced composite behavior through a three dimensional formulation with orthotropic elasticity and orthotropic plasticity using Hill criterion.The isotropic hardening and Johnson Cook parameters are identified from unidirectional tensile tests at different strain rates.The adjustment of Hill’s yield criterion is developed based on yield stresses obtained in tensile tests at different directions.The numerical integration of the constitutive equations is implemented in a user-defined material,UMAT subroutines for the commercial finite element code ABAQUS.Once model parameters are identified using tensile tests,the model needs to be validated by confronting it with other experimental results.That is why experimental and numerical three-point bending tests are carried out in order to validate the proposed model with tests that have not served for the identification.Finally,a numerical parametric study on low velocity impact of a flax/epoxy composite circular plate is investigated.展开更多
In France,the use of flax fibers as reinforcement in composite materials is growing exponentially in the automotive sector,thanks to their good physicochemical properties,environmental reasons,health neutrality and du...In France,the use of flax fibers as reinforcement in composite materials is growing exponentially in the automotive sector,thanks to their good physicochemical properties,environmental reasons,health neutrality and due to the European Council Directives on the reuse,recycling and valorization of car components and materials.The aim of our study is to investigate biochemical,physicochemical,and mechanical properties of technical flax fibers to evaluate the impact of transformation processes(scutching,hackling,and homogenization)on final properties of associated composite materials.Different chemical analysis such as Van Soest(biochemical fraction measurement),FTIR(Fourier Transform InfraRed spectroscopy),and XRD(X-ray diffraction)were carried out on different process modalities and show that there is no significant difference in terms of biochemical fraction and crystallinity index.By the same token,mechanical behavior shows that Young’s modulus is not affected by the transformation process.This result is also observed for thermal behavior.The results highlight the fact that the transformation processes of technical fibers do not really affect their physicochemical and mechanical performances.展开更多
Alkane coupling with CO_(2) by metal-containing zeolites catalysis is found to be a promising way to produce aromatics and syngas in recent years,but the real active sites and the role of CO_(2) are still unclear owin...Alkane coupling with CO_(2) by metal-containing zeolites catalysis is found to be a promising way to produce aromatics and syngas in recent years,but the real active sites and the role of CO_(2) are still unclear owing to the quick evolution of the metallic active sites and the complex reaction processes including direct propane aromatization,CO_(2) hydrogenation,reverse water-gas shift reaction,and propane-CO_(2) coupling aromatization.Herein,Ga/ZSM-5 catalysts were constructed to study the dynamic evolution of the metallic active sites and the role of CO_(2) during the propane and CO_(2) coupling reaction.After optimizing the reaction conditions,a notable propane conversion rate of 97.9%and an impressive aromatics selectivity of 80.6%in hydrocarbons can be achieved at the conditions of 550℃and CO_(2)/C_(3)H_(8) of 4.^(13)CO_(2)isotope experiments illustrate that C-atoms of CO_(2) can enter into CO(86.5%)and aromatics(10.8%)during the propane-CO_(2) coupling reaction process.In situ XANES and FTIR spectroscopies at 550℃and H_(2)/C_(3)H_(8) atmosphere reveal that GaO_(x) species can be gradually dispersed into[GaH_(2)]^(+)/[GaH]^(2+)on the Bronsted acid sites of ZSM-5 zeolite during H_(2) and/or C_(3)H_(8) treatment,which are the real active sites for propane-CO_(2) coupling conversion.In situ CO_(2)-FTIR experiments demonstrate that the[GaH_(2)]^(+)/[GaH]^(2+)species can react with CO_(2) and accelerate the propane and CO_(2) coupling process.This work not only presents a cost-effective avenue for CO_(2) utilization,but also contributes to the active site design for improved alkane and CO_(2) activation in coupling reaction system.展开更多
This paper investigates a fixed-time distributed voltage and reactive power compensation of islanded microgrids using sliding-mode and multi-agent consensus design.A distributed sliding-mode control protocol is propos...This paper investigates a fixed-time distributed voltage and reactive power compensation of islanded microgrids using sliding-mode and multi-agent consensus design.A distributed sliding-mode control protocol is proposed to ensure voltage regulation and reference tracking before the desired preset fixed-time despite the unknown disturbances.Accurate reactive power sharings among distributed generators are maintained.The secondary controller is synthesized without the knowledge of any parameter of the microgrid.It is implemented using a sparse one-way communication network modeled as a directed graph.A comparative simulation study is conducted to highlight the performance of the proposed control strategy in comparison with finite-time and asymptotic control systems with load power variations.展开更多
Abstract In this paper, we explore the fixed point theory of n-vaiued maps using configuration spaces and braid groups, focusing on two fundamental problems, the Wecken property, and the computation of the Nielsen num...Abstract In this paper, we explore the fixed point theory of n-vaiued maps using configuration spaces and braid groups, focusing on two fundamental problems, the Wecken property, and the computation of the Nielsen number. We show that the projective plane （resp. the 2-sphere S2） has the Wecken property for n-valued maps for all n ∈N （resp. all n ≥ 3）. In the case n = 2 and S2, we prove a partial result about the Wecken property. We then describe the Nielsen number of a non-split n-valued map φ ： X → X of an orientable, compact manifold without boundary in terms of the Nielsen coincidence numbers of a certain finite covering q： ）→ X with a subset of the coordinate maps of a lift of the n-valued split map → q ： →X.展开更多
文摘Background:Acute cholangitis is an infection due to the bile duct obstruction.Despite progress in treat-ment,acute cholangitis remains potentially fatal.Early diagnosis and treatment improve the patient out-comes.The present study aimed to identify clinical and biological factors at admission associated with 30-day mortality in acute cholangitis,to build an efficient prognostic score based on these parameters and to study the performances of this new score.Methods:We enrolled all adult patients consecutively hospitalized for acute cholangitis between January 2017 and December 2021.We developed a score system named ProChol using variables significantly asso-ciated with 30-day mortality in multivariate logistic analysis and simplified this system(named sProChol)based on a simple points-based approach.Results:In total,528 patients were included,with an average age of 77±13 years,a male predominance(54.2%)and a majority of lithiasis etiology(66.5%).Mortality in 30 days was 11.9%.In multivariate logis-tic analysis,tumor etiology[adjusted odds ratio(aOR)=15.43,95%confidence interval(CI):5.90-40.40],stent obstruction(aOR=5.12,95%CI:2.02-12.99),hypoalbuminemia(aOR=3.50,95%CI:1.25-9.81),renal failure(aOR=6.51,95%CI:2.62-16.18),oxygen therapy(aOR=4.63,95%CI:1.02-20.92)and cu-rative anticoagulation(aOR=2.60,95%CI:1.23-5.52)were independently associated with the 30-day mortality while fever was a protective factor(aOR=0.37,95%CI:0.16-0.84).ProChol score using these 7 parameters and sProChol using the 3 robust factors(etiology,renal failure and anticoagulation)presented respectively an area under receiver operating characteristic(ROC)curves(AUC)of 0.81 and 0.77,higher than Tokyo(AUC=0.72)and Gravito-Soares et al.score(AUC=0.71).Patients with sProChol≥4 had a significantly higher risk of transfer to intensive care unit(13.3%vs.5.1%;P<0.001)and longer length of stay(P=0.0006).Conclusions:ProChol and sProChol constructed from simple clinico-biological parameters at admission,present interesting performances in predicting the 30-day mortality in acute cholangitis.
文摘Gallstone pancreatitis is the leading cause of acute pancreatitis,accounting for more than 40%of cases.Etiological treatment is a critical issue in acute biliary pancreatitis as it helps reduce the risk of recurrence.Patients who have ex-perienced a complicated form of biliary disease are at high risk for recurrent episodes,and the severity of these new episodes can be unpredictable.In recent years,the role and timing of cholecystectomy and endoscopic retrograde cholan-giopancreatography(ERCP),which are the main therapeutic interventions in the etiological treatment,have been considerably clarified.This review aims to detail the different aspects of the etiological treatment of acute biliary pancreatitis.Currently,it is established that cholecystectomy should be performed early during the initial hospitalization in cases of non-severe acute pancreatitis.However,the optimal timing of this procedure in severe acute pancreatitis remains a subject of debate.Emergency ERCP is no longer indicated for acute biliary pancreatitis,except in cases of associated acute cholangitis.ERCP can be useful for the management of persistent bile duct stones.Finally,the role of interval sphincterotomy in frail or elderly patients or to reduce the risk of re-currence in those awaiting cholecystectomy in cases of severe acute pancreatitis remains to be fully established.
文摘With the increasing railway vehicle speed, pantograph--catenary （PAC） system has become an important part as its incidents still stand among the prin- cipal causes of railway traffic interruption. Indeed, when a rail vehicle moves, the pantograph should constantly press against the underside of the catenary. Nonetheless, it is difficult to get around the complexity of the physical interaction between the pantograph and the contact wire, which could deteriorate the quality of the electricity transfer. Thus, PAC system performances could dramati- cally be reduced because of bad current collection. Therefore, in this paper, we present an output feedback solution in order to design an active control of PAC system. The proposed solution is based on the backstepping control and an adaptive observer that estimates both the （unknown） catenary parameters and the system state. All synthesis steps are given and the closed-loop analysis shows asymptotic tracking behavior regardless of the time-vary- ing catenary stiffness. Furthermore, a numerical example shows that the PAC contact can be regulated with desired effect.
基金supported by the National Natural Science Foundation of China(21971082)the Jilin Province Science and Technology Development Plan(20190201229JC and 20200201096JC)+1 种基金the China Postdoctoral Science Foundation(2018M640280 and 2019T120235)for supporting this workthe National 111 Project(B17020)。
文摘As an effective non-petroleum based process for producing light olefins, the methanol-to-olefin(MTO) route has become an indispensable alternative to the industrial production of light olefins. The silicoaluminophosphate SAPO-34 zeolite(CHA-type structure) has proven to be an efficient industrial catalyst for the production of ethylene and propylene by the MTO reaction. However, the inherent structure and related diffusion limitations of SAPO-34 limit the mass transport and thus cause rapid deactivation of the catalyst. Fabrication of hierarchical SAPO-34 zeolite is one of the most effective strategies to address the intrinsic diffusion limitation. As simple, inexpensive, and efficient approach, the post-synthetic route has attracted considerable attention and widely used to introduce secondary meso-/macropores into the microporous SAPO-34 material. Significant effort has been dedicated to the development of post-synthesis strategies to prepare hierarchical SAPO-34 zeolite, thereby enhancing its catalytic performance in the MTO process. This mini-review addresses the post-synthesis preparation of hierarchical SAPO-34 catalysts and their MTO performance. Furthermore, some current problems and prospects of the post-synthesis route to hierarchical SAPO-34 catalysts are also revised. We expect this minireview to inspire the more efficient preparation of hierarchical SAPO-34 catalysts for the MTO process.
基金supported in part by the NSF of China(Nos.11747312,U1732138,11790325,11790323)the Joint International Laboratory between France and Japan(LIA FJNSP)
文摘Synthesis of superheavy elements beyond oganesson is facing new challenges as new target–projectile combinations are necessary. Guidance from models is thus expected for future experiments. However, hindered fusion models are not well established and predictions in the fission barriers span few MeVs. Consequently, predictions are not reliable. Strategies to constrain both fusion hindrance and fission barriers are necessary to improve the predictive power of the models. But, there is no hope to get an accuracy better than one order of magnitude in fusion–evaporation reactions leading to superheavy elements synthesis.
基金funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No 765704(to CR).
文摘Brain-derived neurotrophic factor(BDNF)is one of the neurotrophins,a specific polypeptide growth factor,which plays a crucial role in the proliferation,differentiation,survival,and death of neurons and non-neuronal cells.It is not only essential to maintain the balance between death on one side and survival of neurons on the other,but also it mediates additional higher-order activities such as learning,memory,and behavior.It is initially synthesized as a precursor protein,proBDNF,that can be secreted as it is or it can be cleaved intracellularly by furin and proconvertases,or extracellularly by extracellular proteases such as matrix metalloprotease-9 and matrix metalloprotease-2,or plasmin to give mature BDNF.
基金supported by the Institut National du Cancer (INCa Convention no. 2010-368)+2 种基金the Hauts-de-France Region (Convention No. 14003399)the French Agency of the Environment and Energy (ADEME Convention no. 1494c008283-84)
文摘Particulate matter in ambient air constitutes a complex mixture of fine and ultrafine particles composed of various chemical compounds including metals, ions, and organics. A multidisciplinary approach was developed by studying physico-chemical characteristics and mechanisms involved in the toxicity of particulate atmospheric pollution. PM0.3-2.s and PM2.5 including ultrafine particles were sampled in Dunkerque, a French industrialized seaside city. PM samples were characterized from a chemical and toxicological point of view. Physico-chemical characterization evidenced that PM2.5 comes from several sources： natural ones, such as soil resuspension and marine sea-salt emissions, as well as anthropogenic ones, such as shipping traffic, road traffic, and industrial activities. Human BEAS-2B tung cells were exposed to PM0.3-2.5, or to the Extractable Organic Matter （EOM） of PM0.3-2.5 and PM2.s. These exposures induced several mechanisms of action implied in the genotoxicity, such as oxidative DNA adducts and DNA Damage Response. The toxicity of PM-EOM was higher for the sample including the ultrafine fraction （PM2.5） containing also higher concentrations of polycyclic aromatic hydrocarbons. These results evidenced the major role of organic compounds in the toxicity of PM.
文摘The first case of Prinzmetal angina was described in 1959 by Prinzmetal, et al. Since this description, several triggering factors have been associated with vasospastic angina （VA） and included： illicit drugs such as cocaine, amphetamine or marijuana, but also bitter-orange, alcohol, butane, chemotherapy drugs, over-the-counter medication and different antibiotics. Smoking is also a major risk factor for developing VA.t21 Thus, except for smoking, many of conventional atherosclerosis risk factors do not appear to be applicable to VA.t21 However, vasospastic angina can also occur without any triggering factor.
文摘CO2 adsorption on the surface of hydrotalcite-derived mixed oxide catalysts was investigated under low pressure glow discharge plasma in opercindo conditions via FT-IR spectroscopy.Nickel catalysts were promoted with various transition metal species(Ce,Fe,La,Zr)to influence their physico-chemical properties.Fe and Zr species were successfully incorporated into hydrotalcite brucite layers.After calcination formed a single phase with Ni(Mg,A1)O mixed oxide,while La and Ce species formed separate phases.This had a consequence in the distribution of surface basic sites as well as in the affinity to CO produced upon CO2 dissociation in plasma.Plasma treatment activated the surface of prepared materials and changed their properties via the generation of strong basic sites associated with low coordinated surface oxygen anions.Moreover,the CO2 adsorption capacity of prepared materials increased after plasma treatment.
文摘The present study analyses the spatio-temporal variability of the macrozoobenthos from the intertidal zone of the Kneiss Islands (Gulf of Gabès, Tunisia). Samples were collected once from 34 stations, while seasonal variations were studied by sampling four times at 12 stations over the period 2013-2014. A total of 159 macrobenthos taxa associated with intertidal Zostera noltei beds are identified from the 34 stations, with a taxonomic dominance of crustaceans (32%), molluscs (29%) and annelids (27%). Abundance varies from 9244 to 36,844 ind·m<sup>-2</sup> with a mean value of 14,346 ind·m<sup>-2</sup>. Analysis of the trophic structure shows that the majority of stations are strongly represented by carnivores (41%), followed by the non-selective deposit feeders (16%). Cluster analysis and multidimensional scaling allow identification of three main benthic assemblages based on species abundance, corresponding to different sediment types and organic matter contents. The seasonal variability in abundance, diversity and community structure is mainly due to spring and summer recruitment. The biotic indices (i.e. AMBI, BO2A and BENTIX) show that the intertidal area of Kneiss Islands exhibits a good ecological status.
基金supported by the National Natural Science Foundation of China(Grant 21971082 and 22001090)the Jilin Province Science and Technology Development Plan(Grant 20190201229JC and 20200201096JC)。
文摘Zeolites and zeo-type materials with nanosized dimensions are of great practical interest owing to their favorable transport properties,faster adsorption kinetics,and large external surface area.This mini-review presents recent developments in the organic template-free synthesis of nanosized zeolites and related materials.The advantages and challenges of these methods are addressed with particular attention to the green synthesis of nanozeolites.
基金supported by ANSES (French Agency for Food,Environmental and Occupational Health and SafetyPUFBIO project,Grant number EST-2017-190)+5 种基金co-supported by the Regional Council of Normandy and the European Union in the framework of the ERDF-ESF (CellSTEM project)a PhD fellowship funded by ADEME(Agency for Ecological Transition)financed by the Labex SynOrg(ANR-11-LABX-0029)the European Regional Development Fund (ERDF HN0001343)Financial support from the National Fourier transform ion cyclotron resonance network (FR 3624 CNRS)the European Union’s Horizon 2020 Research Infrastructures program (grant agreement 731077).
文摘Ultrafine particles represent a growing concern in the public health community but their precise role in many illnesses is still unknown. This lack of knowledge is related to the experimental difficulty in linking their biological effects to their multiple properties, which are important determinants of toxicity. Our aim is to propose an interdisciplinary approach to study fine(FP) and ultrafine(UFP) particles, generated in a controlled manner using a mini CAST(Combustion Aerosol Standard) soot generator used with two different operating conditions(CAST1 and CAST3). The chemical characterization was performed by an untargeted analysis using ultra-high resolution mass spectrometry. In conjunction with this approach, subsequent analysis by gas chromatography–mass spectrometry(GC–MS) was performed to identify polycyclic aromatic hydrocarbons(PAH). CAST1 enabled the generation of FP with a predominance of small PAH molecules, and CAST3 enabled the generation of UFP, which presented higher numbers of carbon atoms corresponding to larger PAH molecules. Healthy normal human bronchial epithelial(NHBE) cells differentiated at the air-liquid interface(ALI) were directly exposed to these freshly emitted FP and UFP. Expression of MUC5AC, FOXJ1, OCLN and ZOI as well as microscopic observation confirmed the ciliated pseudostratified epithelial phenotype. Study of the mass deposition efficiency revealed a difference between the two operating conditions, probably due to the morphological differences between the two categories of particles. We demonstrated that only NHBE cells exposed to CAST3 particles induced upregulation in the gene expression of IL-8 and NQO1. This approach offers new perspectives to study FP and UFP with stable and controlled properties.
文摘The integrated molar absorption coefficients for ν(OH) (3655 cm-1), δ(OH) (Q branch at 1176 cm-1 or whole bands), [ν(CCring) + δ(OH)] (Q branch at 1344 cm-1 or whole bands) and γ(CH) (752 cm-1) were determined at 342 K, by recording infrared spectra of pure gaseous phenol at different partial pressure (from 0 to 33 Pa). The integrated molar absorption coefficients (ε) values were obtained with a good reproducibility and the relative uncertainty on the given values is below 2%. The influence of water on the integrated molar absorption coefficients of phenol has been investigated in a large range of nwater/nphenol values (from 0.5 to 6.1 and from 44 to 94) using distinct setups. The infrared spectra of a gas mixture containing a constant amount of phenol and different amount of water were recorded (closed cell) whereas in dynamic condition (under flow) the water partial pressure was kept constant at 1.3 kPa and the phenol partial pressure was increased from 0 to 30 Pa. It is here demonstrated that, at 342 or 355 K, the presence of water does not affect the epsilon values of δ(OH) and [ν(CCring) + δ(OH)] bands.
文摘Based on experimental test results,flax fiber reinforced polymer composites are characterized by nonlinear visco-elastoplastic behavior.The aim of this work is to model the quasi-unidirectional flax fiber reinforced composite behavior through a three dimensional formulation with orthotropic elasticity and orthotropic plasticity using Hill criterion.The isotropic hardening and Johnson Cook parameters are identified from unidirectional tensile tests at different strain rates.The adjustment of Hill’s yield criterion is developed based on yield stresses obtained in tensile tests at different directions.The numerical integration of the constitutive equations is implemented in a user-defined material,UMAT subroutines for the commercial finite element code ABAQUS.Once model parameters are identified using tensile tests,the model needs to be validated by confronting it with other experimental results.That is why experimental and numerical three-point bending tests are carried out in order to validate the proposed model with tests that have not served for the identification.Finally,a numerical parametric study on low velocity impact of a flax/epoxy composite circular plate is investigated.
基金funded by FEDER and it was carried out in collaboration with LSM and LINEO Company.
文摘In France,the use of flax fibers as reinforcement in composite materials is growing exponentially in the automotive sector,thanks to their good physicochemical properties,environmental reasons,health neutrality and due to the European Council Directives on the reuse,recycling and valorization of car components and materials.The aim of our study is to investigate biochemical,physicochemical,and mechanical properties of technical flax fibers to evaluate the impact of transformation processes(scutching,hackling,and homogenization)on final properties of associated composite materials.Different chemical analysis such as Van Soest(biochemical fraction measurement),FTIR(Fourier Transform InfraRed spectroscopy),and XRD(X-ray diffraction)were carried out on different process modalities and show that there is no significant difference in terms of biochemical fraction and crystallinity index.By the same token,mechanical behavior shows that Young’s modulus is not affected by the transformation process.This result is also observed for thermal behavior.The results highlight the fact that the transformation processes of technical fibers do not really affect their physicochemical and mechanical performances.
基金supported by the National Key Research and Development Program of China (No.2022YFE0116000)the National Natural Science Foundation of China (No.22288101,21991092,21991090,22202193,and 22172166)+1 种基金the Youth Innovation Promotion Association CAS (2021182)the Innovation Research Foundation of Dalian Institute of Chemical Physics,Chinese Academy of Sciences (DICP I202429 and I202217)。
文摘Alkane coupling with CO_(2) by metal-containing zeolites catalysis is found to be a promising way to produce aromatics and syngas in recent years,but the real active sites and the role of CO_(2) are still unclear owing to the quick evolution of the metallic active sites and the complex reaction processes including direct propane aromatization,CO_(2) hydrogenation,reverse water-gas shift reaction,and propane-CO_(2) coupling aromatization.Herein,Ga/ZSM-5 catalysts were constructed to study the dynamic evolution of the metallic active sites and the role of CO_(2) during the propane and CO_(2) coupling reaction.After optimizing the reaction conditions,a notable propane conversion rate of 97.9%and an impressive aromatics selectivity of 80.6%in hydrocarbons can be achieved at the conditions of 550℃and CO_(2)/C_(3)H_(8) of 4.^(13)CO_(2)isotope experiments illustrate that C-atoms of CO_(2) can enter into CO(86.5%)and aromatics(10.8%)during the propane-CO_(2) coupling reaction process.In situ XANES and FTIR spectroscopies at 550℃and H_(2)/C_(3)H_(8) atmosphere reveal that GaO_(x) species can be gradually dispersed into[GaH_(2)]^(+)/[GaH]^(2+)on the Bronsted acid sites of ZSM-5 zeolite during H_(2) and/or C_(3)H_(8) treatment,which are the real active sites for propane-CO_(2) coupling conversion.In situ CO_(2)-FTIR experiments demonstrate that the[GaH_(2)]^(+)/[GaH]^(2+)species can react with CO_(2) and accelerate the propane and CO_(2) coupling process.This work not only presents a cost-effective avenue for CO_(2) utilization,but also contributes to the active site design for improved alkane and CO_(2) activation in coupling reaction system.
基金This work was supported by Morocco’s National Center for Scientific and Technical Research within the Research Excellence Scholarships Program.
文摘This paper investigates a fixed-time distributed voltage and reactive power compensation of islanded microgrids using sliding-mode and multi-agent consensus design.A distributed sliding-mode control protocol is proposed to ensure voltage regulation and reference tracking before the desired preset fixed-time despite the unknown disturbances.Accurate reactive power sharings among distributed generators are maintained.The secondary controller is synthesized without the knowledge of any parameter of the microgrid.It is implemented using a sparse one-way communication network modeled as a directed graph.A comparative simulation study is conducted to highlight the performance of the proposed control strategy in comparison with finite-time and asymptotic control systems with load power variations.
基金supported by Fundao de Amparo a Pesquisa do Estado de So Paulo(FAPESP)Projeto Temtico Topologia Algébrica,Geométrica e Diferencial(Grant No.2012/24454-8)supported by the same project as well as the Centre National de la Recherche Scientifique(CNRS)/Fundao de Amparo a Pesquisa do Estado de So Paulo(FAPESP)Projet de Recherche Conjoint(PRC)project(Grant No.275209)
文摘Abstract In this paper, we explore the fixed point theory of n-vaiued maps using configuration spaces and braid groups, focusing on two fundamental problems, the Wecken property, and the computation of the Nielsen number. We show that the projective plane （resp. the 2-sphere S2） has the Wecken property for n-valued maps for all n ∈N （resp. all n ≥ 3）. In the case n = 2 and S2, we prove a partial result about the Wecken property. We then describe the Nielsen number of a non-split n-valued map φ ： X → X of an orientable, compact manifold without boundary in terms of the Nielsen coincidence numbers of a certain finite covering q： ）→ X with a subset of the coordinate maps of a lift of the n-valued split map → q ： →X.
