In this paper, the problem of load transportation and robust mitigation of payload oscillations in uncertain tower-cranes is addressed. This problem is tackled through a control scheme based on the philosophy of activ...In this paper, the problem of load transportation and robust mitigation of payload oscillations in uncertain tower-cranes is addressed. This problem is tackled through a control scheme based on the philosophy of active-disturbance-rejection. Here, a general disturbance model built with two dominant components: polynomial and harmonic, is stated. Then, a disturbance observer is formulated through state-vector augmentation of the tower-crane model. Thus, better performance of estimations for system states and disturbances is achieved. The control law is then formulated to actively reject the disturbances but also to accommodate the closed-loop system dynamics even under system uncertainty. The proposed control schema is validated via experimentation using a small-scale tower-crane,and compared with other relevant active disturbance rejection control(ADRC)-based techniques. The experimental results show that the proposed control scheme is robust under parametric uncertainty of the system, and provides improved attenuation of payload oscillations even under system uncertainty.展开更多
This paper presents a novel active disturbance rejection control(ADRC)scheme based on a cascade connection of generalized proportional integral observers(GPIOs)with internal models designed to estimate both polynomial...This paper presents a novel active disturbance rejection control(ADRC)scheme based on a cascade connection of generalized proportional integral observers(GPIOs)with internal models designed to estimate both polynomial and resonant disturbances.In this estimator structure,referred to as Cascade GPIO(CGPIO),the total disturbance sensitivity is the product of the sensitivities at each cascade level.This approach improves system performance against both periodic and non-periodic disturbances and enhances robustness under frequency variations in harmonic components.Additionally,the decoupled nature of the estimator reduces the order of the GPIOs,thereby simplifying tuning and limiting observer gains.The proposed control scheme is supported by a frequency-domain analysis and is experimentally validated in the current control of a grid-connected converter subject to control gain uncertainties,harmonic distortion,frequency deviations,and measurement noise.Experimental results demonstrate that the CGPIO-based ADRC outperforms benchmark solutions,including proportional-integral(PI)and proportional-resonant(PR)controllers.展开更多
In this study,we investigate the potential of mark-weighted angular correlation functions,which integrateβ-cosmic-web classification with angular correlation function analysis to improve cosmological constraints.Usin...In this study,we investigate the potential of mark-weighted angular correlation functions,which integrateβ-cosmic-web classification with angular correlation function analysis to improve cosmological constraints.Using SDSS DR12 CMASS-NGC galaxies and mock catalogs withΩ_(m)varying from 0.25 to 0.40,we assess the discriminative power of different statistics via the average improvement in chi-squared,ΔX^(2),across six redshift bins.This metric quantifies how effectively each statistic distinguishes between different cosmological models.Incorporating cosmic-web weights leads to substantial improvements.Using statistics weighted by the mean neighbor distance(Dnei)increasesΔX^(2)by approximately 40%–130%,while applying inverse mean neighbor distance weighting(1/Dnei)yields even larger gains,boostingΔX^(2)by a factor of 2–3 compared to traditional unweighted angular statistics.These enhancements are consistent with previous 3D clustering results,demonstrating the superior sensitivity of theβ-weighted approaches.Our method,based on thin redshift slices,is particularly suitable for slitless surveys(e.g.,Euclid,CSST)where redshift uncertainties limit 3D analyses.This study also offers a framework for applying marked statistics to 2D angular clustering.展开更多
Emerging infectious diseases are a major threat to biodiversity and an important public health issue.Flaviviruses are the cause of several emerging vector-borne zoonotic arboviruses whose distribution is currently inc...Emerging infectious diseases are a major threat to biodiversity and an important public health issue.Flaviviruses are the cause of several emerging vector-borne zoonotic arboviruses whose distribution is currently increasing in Europe.The evidence that West Nile virus(WNV)circulates in resident and migratory species has implications for both animal and public health and should therefore be studied in depth.USUTU(USUV),Bagaza(BAGV)and tick-borne encephalitis virus(TBEV)are other viruses that are beginning to spread more widely.An integrated surveillance program,namely in birds,is essential for reducing the risk of infection in human populations within the One Health principles.In the present study,wild birds admitted to wildlife rehabilitation centers in Portugal were sampled.Two hundred eight blood samples were assayed serologically for antibodies to flaviviruses by using a commercial ELISA kit.An over-all seroprevalence of 19.6%(95%confidence interval[CI]:13.7-26.7%)was observed.Antibodies against flaviviruses were detected in 13(35.1%)different species of wild birds.Accipitriformes(26.7%;95%CI:18.5-36.2%)and Strigi-formes(26.7%;95%CI:14.6-42.0%)were the orders with the highest seroprevalence rates recorded.There were no statistically significant differences(p=0.725)between the geographical regions(NUTSⅡ)studied,but a statistically significant difference(p=0.017)was found between sex(male:34.4%;female:4.8%).A higher seroprevalence was detected in adults(32.1%)than in juvenile birds(9.3%)(p=0.014),and age was considered a risk factor for flavivirus infection in wild birds(odds ratio 1.4;95%CI:0.5-4.0).More epidemiological studies are needed in Portugal since the actual spread of the genus Flavivirus throughout the country is unknown.展开更多
This work applies stress tensors inversions and quantification of fracture patterns along the Mesa de Los Santos, in the Eastern Cordillera of Colombia, to better understand the potential fluid flow. It thus contribut...This work applies stress tensors inversions and quantification of fracture patterns along the Mesa de Los Santos, in the Eastern Cordillera of Colombia, to better understand the potential fluid flow. It thus contributes to the conceptual hydrogeological model. The area was subdivided into three blocks, separated by the NW Potreros and the Los Santos faults, having minor inner faults of different orientations. This separation facilitates the analysis of the fractures measured in the field, which in general show high dip angles and a conjugate geometry in the northern block, tension fractures(Mode I) in the central block, and a random distribution in the southwestern block. WinTensor treatment of slickensides yielded a maximum horizontal stress(SHmax) of 111o, which coincides with the WNW-ESE tensor observed from the conjugate and tension joints. We then used Frac Pa Q to generate interpolation maps of fracture intensity and density. The maps show the highest values in the central block and the lowest in the northern block,where the precipitation is higher, causing intensive rock weathering and homogenization of the fracture planes. Although the highest values of connectivity by line are found to the south of the mesa, we suggest the possibility of greater flow from the recharge zone(NE) along bedding planes and open NW-SE fractures.展开更多
In a time characterized by the availability of vast amounts of data,the effective utilization of information is critical for timely decision-making in military operations.However,processing large amounts of data requi...In a time characterized by the availability of vast amounts of data,the effective utilization of information is critical for timely decision-making in military operations.However,processing large amounts of data requires computational resources and time.Therefore,decision makers have used data-centric technologies to take advantage of public and private data sources to support military operations.This survey explores the integration and application of data-centric technologies,such as data analytics,data science,and machine learning,to optimize decision-making workflows within military contexts supporting the deployment of military assets and resources.To address the information gap,this article presents a literature review,specifically a survey.Our survey examines the use of the mentioned technologies to process and analyze information that contributes to the phases of situational awareness,and planning in military environments.We then introduce a taxonomy of the approaches associated with implementing these technologies in military scenarios.Furthermore,we discuss relevant factors for the seamless integration of data-centric technologies into military decision-making processes,and reveal the importance of specialized personnel,architectures,and cybersecurity issues in the task of developing prototypes and models.The findings of this paper aim to provide valuable insights for military institutions,offering a deeper understanding of the use of data-centric technologies as innovative practices to enhance the effectiveness of military decision-making.展开更多
Background and Objective: HIV, hepatitis B virus (HBV) and hepatitis C virus (HCV) are very widespread in the world, however, less than 20% of the people affected are diagnosed and treated. This study aimed to determi...Background and Objective: HIV, hepatitis B virus (HBV) and hepatitis C virus (HCV) are very widespread in the world, however, less than 20% of the people affected are diagnosed and treated. This study aimed to determine the prevalence of HIV, HCV and HBV co-infections in pregnant women at Bangui Community University Hospital and the cost of screening. Methods: A cross-sectional study involving consenting pregnant women who came for antenatal care was performed. HIV, HCV antibodies and HBV antigens were detected using Exacto Triplex<sup>?</sup> HIV/HCV/HBsAg rapid test, cross-validated by ELISA tests. Sociodemographic and professional data, the modes of transmission and prevention of HIV and both hepatitis viruses were collected in a standard sheet and analyzed using the Epi-Info software version 7. Results: Pregnant women aged 15 to 24 were the most affected (45.3%);high school girls (46.0%), and pregnant women living in cohabitation (65.3%) were the most represented. Twenty-five (16.7%) worked in the formal sector, 12.7% were unemployed housewives and the remainder in the informal sector. The prevalence of HIV, HBV, and HCV viruses was 11.8%, 21.9% and 22.2%, respectively. The prevalence of co-infections was 8.6% for HIV-HBV, 10.2% for HIV-HCV, 14.7% for HBV-HCV and 6.5% for HIV-HBV-HCV. All positive results and 10% of negative results by the rapid test were confirmed by ELISA tests. The serology of the three viruses costs 39,000 FCFA (60 Euros) by ELISA compared to 10,000 FCFA (15.00 Euros) with Exacto Triplex<sup>?</sup> HIV/HCV/AgHBs (BioSynex, Strasbourg, France). Conclusion: The low level of education and awareness of hepatitis are barriers to development and indicate the importance of improving the literacy rate of women in the Central African Republic (CAR). Likewise, the high prevalence of the three viruses shows the need for the urgent establishment of a national program to combat viral hepatitis in the CAR.展开更多
The present study aims to develop multilayer barrier-bioactive hybrid sol-gel coatings from a mixture of the silane precursors tetraethylorthosilicate(TEOS)and glycidoxypropyltriethoxysilane(GPTMS)deposited on the Ele...The present study aims to develop multilayer barrier-bioactive hybrid sol-gel coatings from a mixture of the silane precursors tetraethylorthosilicate(TEOS)and glycidoxypropyltriethoxysilane(GPTMS)deposited on the Elektron 21 magnesium alloy.The purpose of the inner layer(barrier coating)was to provide corrosion protection to the magnesium alloy,whereas the outer layer(bioactive coating)was doped with different Ca and Mg contents to produce a bioactive material.The coatings were characterised using scanning electron microscopy(SEM)and their corrosion behaviour was evaluated by anodic polarisation and electrochemical impedance spectroscopy after immersion in simulated body fluid(SBF)at 37±0.5°C.The experimental results showed that the multilayer coatings increased the corrosion resistance of the alloy up to three orders of magnitude during immersion in SBF solution.On the other hand,the presence of Ca and Mg in the bioactive coating promoted the growth of apatite-like phases.However,an increment of salt content favoured the formation of porous coatings,which allowed the access of the electrolyte to the substrate leading to their rapid deterioration.Despite the latter,this research endorses the premise that the TEOS-GPTMS hybrid system represents a promising alternative to produce bifunctional barrier-bioactive coatings.展开更多
Due to metal leaching and poor catalyst stability, the chemical industry's fine chemical and pharmaceutical sectors have been historically reluctant to use supported transition metal catalysts to manufacture fine ...Due to metal leaching and poor catalyst stability, the chemical industry's fine chemical and pharmaceutical sectors have been historically reluctant to use supported transition metal catalysts to manufacture fine chemicals and active pharmaceutical ingredients. With the advent of new generation supported metal catalysts and flow chemistry, we argue in this study, this situation is poised to quickly change. Alongside heterogenized metal nanoparticles, both single-site molecular and single-atom catalyst will become ubiquitous. This study offers a critical outlook taking into account both technical and economic aspects.展开更多
Background:Species turnover(β-diversity)along elevational gradients is one of the most important concepts in plant ecology.However,there is a lack of consensus about the main driving mechanisms of treeβ-diversity at...Background:Species turnover(β-diversity)along elevational gradients is one of the most important concepts in plant ecology.However,there is a lack of consensus about the main driving mechanisms of treeβ-diversity at local scales in very diverse ecosystems(e.g.,Andean mountains),as well as how the sampling effect can alterβ-diversity estimations.Recently,it has been hypothesized that patterns of change inβ-diversity at local scales along elevational gradients are driven by sampling effects stemming from differences in the size of the species pool rather than by underlying community assembly mechanisms.Thus,we aim to evaluate the relative extent to which sampling effects,such as species pool size,grain size,and tree size cut-off,determine species sorting,and thus,the variability ofβ-diversity at local scales along elevational gradients in the northwest of Colombia.Results:Using 151-ha permanent plots spread out along a 3000m elevational gradient,we used standardizedβ-deviation to assess the extent to which either sampling effects or the community assembly mechanisms determine the changes in species composition at local scales.Standardizedβ-deviation was measured as the difference between the observed and nullβ-diversity divided by the standard deviation of the nullβ-diversity.We found that the magnitude of change in localβ-deviation along the elevational gradient was significant and dependent on the employed spatial grain size and tree size cut-off.However,β-deviation increased with elevation in all sampling designs,which suggests that underlying community assembly mechanisms play a key role in shaping localβ-diversity along the elevational gradient.Conclusions:Our findings suggest that grain size enlargement and the inclusion of trees with small diameters will improve our ability to quantify the extent to which the community assembly mechanisms shape patterns ofβ-diversity along elevational gradients.Overall,we emphasize the scale-dependent nature of the assessment ofβ-diversity.Likewise,we call for the need of a new generation of enlarged forest inventory plots along gradients of elevation in tropical forests that include small individuals to improve our understanding about the likely response of diversity and function to global change.展开更多
This work proposes a soft sensor based on a phenomenological model for online estimation of the density and viscosity of a slurry flowing through a pipe-and-fittings assembly(PFA). The model is developed considering t...This work proposes a soft sensor based on a phenomenological model for online estimation of the density and viscosity of a slurry flowing through a pipe-and-fittings assembly(PFA). The model is developed considering the conservation principle applied to mass and momentum transfer and considering frictional energy losses to include the variables directly affecting slurry properties. A reported proposal for state observers with unknown inputs is used to develop the first block of the observer structure. The second block is constructed with two options for evaluating slurry viscosity, generating two possible estimator structures, which are tested using real data. A comparison between them indicates different uses and capabilities according to available process information.展开更多
Experimental mole fraction solubility of lamotrigine(LTG)in ternary aqueous mixtures of two ionic liquids(ILs),1-hexyl and 1-octyl-3-methylimidazolium bromide,[HMIm][Br]and[OMIm][Br]were reported at several temperatur...Experimental mole fraction solubility of lamotrigine(LTG)in ternary aqueous mixtures of two ionic liquids(ILs),1-hexyl and 1-octyl-3-methylimidazolium bromide,[HMIm][Br]and[OMIm][Br]were reported at several temperatures T=(293.15 to 313.15)K.The van’t Hoff and(Jouyban-Acree-van’t Hoff,E-Jouyban-Acree-van’t Hoff,e-NRTL,UNIQUAC and Wilson)models were used to correlate the solubility data.The comparison of the models with temperature and solvent composition dependencies shows that the Wilson model has the minimum ARD which are relatively close to those obtained from Jouyban-Acree-van’t Hoff and E-Jouyban-Acree-van’t Hoff models and maximum ARD belonged to the UNIQUAC model.The order of ARDs for these models is:Wilson b Jouyban-Acree-van’t Hoff,E-Jouyban-Acree-van’t Hoff b e-NRTL b UNIQUAC.Moreover,the apparent thermodynamic functions,Gibbs free energy,enthalpy and entropy of dissolution and mixing were calculated based on the van’t Hoff and Gibbs free energy equations.The strong LTG-ILs interactions and enthalpic contribution of the dissolution process resulted from the calculated thermodynamic functions.展开更多
In this work,NiTi samples with different thicknesses(0.15-1.00 mm)were fabricated by laser powder bed fusion(LPBF)under variable scanning speeds(500-1200 mm s^(-1)).The densification behavior,phase transformation beha...In this work,NiTi samples with different thicknesses(0.15-1.00 mm)were fabricated by laser powder bed fusion(LPBF)under variable scanning speeds(500-1200 mm s^(-1)).The densification behavior,phase transformation behavior,and mechanical properties of the sample with different thicknesses are studied.The results indicate a strong size effect in the LPBF-fabricated NiTi alloy.The decrease of the sample thickness results in(i)the increase of porosity,(ii)the decrease of the number of adhered NiTi powder particles at the surface,(iii)the monotonous decrease of the martensitic transformation temperatures(MTTs),and(iv)the decrease of the shape recovery temperature.The influence of sample thickness on the melt-pool behavior,and thus the microstructure and performance of NiTi alloys are discussed.It is suggested that the melt-pool is deeper and narrower in the thin samples than in the thick samples.We conclude that,apart from the LPBF process conditions,the sample dimensions have also to be considered to fabricate NiTi structures with predictable properties.展开更多
文摘In this paper, the problem of load transportation and robust mitigation of payload oscillations in uncertain tower-cranes is addressed. This problem is tackled through a control scheme based on the philosophy of active-disturbance-rejection. Here, a general disturbance model built with two dominant components: polynomial and harmonic, is stated. Then, a disturbance observer is formulated through state-vector augmentation of the tower-crane model. Thus, better performance of estimations for system states and disturbances is achieved. The control law is then formulated to actively reject the disturbances but also to accommodate the closed-loop system dynamics even under system uncertainty. The proposed control schema is validated via experimentation using a small-scale tower-crane,and compared with other relevant active disturbance rejection control(ADRC)-based techniques. The experimental results show that the proposed control scheme is robust under parametric uncertainty of the system, and provides improved attenuation of payload oscillations even under system uncertainty.
文摘This paper presents a novel active disturbance rejection control(ADRC)scheme based on a cascade connection of generalized proportional integral observers(GPIOs)with internal models designed to estimate both polynomial and resonant disturbances.In this estimator structure,referred to as Cascade GPIO(CGPIO),the total disturbance sensitivity is the product of the sensitivities at each cascade level.This approach improves system performance against both periodic and non-periodic disturbances and enhances robustness under frequency variations in harmonic components.Additionally,the decoupled nature of the estimator reduces the order of the GPIOs,thereby simplifying tuning and limiting observer gains.The proposed control scheme is supported by a frequency-domain analysis and is experimentally validated in the current control of a grid-connected converter subject to control gain uncertainties,harmonic distortion,frequency deviations,and measurement noise.Experimental results demonstrate that the CGPIO-based ADRC outperforms benchmark solutions,including proportional-integral(PI)and proportional-resonant(PR)controllers.
基金supported by the Ministry of Science and Technology of China(2020SKA0110401,2020SKA0110402 and 2020SKA0110100)the National Key Research and Development Program of China(2018YFA0404504,2018YFA0404601 and 2020YFC2201600)+2 种基金the National Natural Science Foundation of China(12373005,11890691,12205388,12220101003 and 12473097)the China Manned Space Project with numbers CMS-CSST-2021(A02,A03,B01)Guangdong Basic and Applied Basic Research Foundation(2024A1515012309)。
文摘In this study,we investigate the potential of mark-weighted angular correlation functions,which integrateβ-cosmic-web classification with angular correlation function analysis to improve cosmological constraints.Using SDSS DR12 CMASS-NGC galaxies and mock catalogs withΩ_(m)varying from 0.25 to 0.40,we assess the discriminative power of different statistics via the average improvement in chi-squared,ΔX^(2),across six redshift bins.This metric quantifies how effectively each statistic distinguishes between different cosmological models.Incorporating cosmic-web weights leads to substantial improvements.Using statistics weighted by the mean neighbor distance(Dnei)increasesΔX^(2)by approximately 40%–130%,while applying inverse mean neighbor distance weighting(1/Dnei)yields even larger gains,boostingΔX^(2)by a factor of 2–3 compared to traditional unweighted angular statistics.These enhancements are consistent with previous 3D clustering results,demonstrating the superior sensitivity of theβ-weighted approaches.Our method,based on thin redshift slices,is particularly suitable for slitless surveys(e.g.,Euclid,CSST)where redshift uncertainties limit 3D analyses.This study also offers a framework for applying marked statistics to 2D angular clustering.
基金funded by the Portuguese Foundation for Science and Technology(FCT)sup-ported by the projects UIDB/00772/2020(https://doi.org/10.54499/UIDB/00772/2020)。
文摘Emerging infectious diseases are a major threat to biodiversity and an important public health issue.Flaviviruses are the cause of several emerging vector-borne zoonotic arboviruses whose distribution is currently increasing in Europe.The evidence that West Nile virus(WNV)circulates in resident and migratory species has implications for both animal and public health and should therefore be studied in depth.USUTU(USUV),Bagaza(BAGV)and tick-borne encephalitis virus(TBEV)are other viruses that are beginning to spread more widely.An integrated surveillance program,namely in birds,is essential for reducing the risk of infection in human populations within the One Health principles.In the present study,wild birds admitted to wildlife rehabilitation centers in Portugal were sampled.Two hundred eight blood samples were assayed serologically for antibodies to flaviviruses by using a commercial ELISA kit.An over-all seroprevalence of 19.6%(95%confidence interval[CI]:13.7-26.7%)was observed.Antibodies against flaviviruses were detected in 13(35.1%)different species of wild birds.Accipitriformes(26.7%;95%CI:18.5-36.2%)and Strigi-formes(26.7%;95%CI:14.6-42.0%)were the orders with the highest seroprevalence rates recorded.There were no statistically significant differences(p=0.725)between the geographical regions(NUTSⅡ)studied,but a statistically significant difference(p=0.017)was found between sex(male:34.4%;female:4.8%).A higher seroprevalence was detected in adults(32.1%)than in juvenile birds(9.3%)(p=0.014),and age was considered a risk factor for flavivirus infection in wild birds(odds ratio 1.4;95%CI:0.5-4.0).More epidemiological studies are needed in Portugal since the actual spread of the genus Flavivirus throughout the country is unknown.
基金the financial backing provided by the Universidad Industrial de Santander through project 2534 “Estudio Integral del Agua en la Mesa de Los Santos”。
文摘This work applies stress tensors inversions and quantification of fracture patterns along the Mesa de Los Santos, in the Eastern Cordillera of Colombia, to better understand the potential fluid flow. It thus contributes to the conceptual hydrogeological model. The area was subdivided into three blocks, separated by the NW Potreros and the Los Santos faults, having minor inner faults of different orientations. This separation facilitates the analysis of the fractures measured in the field, which in general show high dip angles and a conjugate geometry in the northern block, tension fractures(Mode I) in the central block, and a random distribution in the southwestern block. WinTensor treatment of slickensides yielded a maximum horizontal stress(SHmax) of 111o, which coincides with the WNW-ESE tensor observed from the conjugate and tension joints. We then used Frac Pa Q to generate interpolation maps of fracture intensity and density. The maps show the highest values in the central block and the lowest in the northern block,where the precipitation is higher, causing intensive rock weathering and homogenization of the fracture planes. Although the highest values of connectivity by line are found to the south of the mesa, we suggest the possibility of greater flow from the recharge zone(NE) along bedding planes and open NW-SE fractures.
文摘In a time characterized by the availability of vast amounts of data,the effective utilization of information is critical for timely decision-making in military operations.However,processing large amounts of data requires computational resources and time.Therefore,decision makers have used data-centric technologies to take advantage of public and private data sources to support military operations.This survey explores the integration and application of data-centric technologies,such as data analytics,data science,and machine learning,to optimize decision-making workflows within military contexts supporting the deployment of military assets and resources.To address the information gap,this article presents a literature review,specifically a survey.Our survey examines the use of the mentioned technologies to process and analyze information that contributes to the phases of situational awareness,and planning in military environments.We then introduce a taxonomy of the approaches associated with implementing these technologies in military scenarios.Furthermore,we discuss relevant factors for the seamless integration of data-centric technologies into military decision-making processes,and reveal the importance of specialized personnel,architectures,and cybersecurity issues in the task of developing prototypes and models.The findings of this paper aim to provide valuable insights for military institutions,offering a deeper understanding of the use of data-centric technologies as innovative practices to enhance the effectiveness of military decision-making.
文摘Background and Objective: HIV, hepatitis B virus (HBV) and hepatitis C virus (HCV) are very widespread in the world, however, less than 20% of the people affected are diagnosed and treated. This study aimed to determine the prevalence of HIV, HCV and HBV co-infections in pregnant women at Bangui Community University Hospital and the cost of screening. Methods: A cross-sectional study involving consenting pregnant women who came for antenatal care was performed. HIV, HCV antibodies and HBV antigens were detected using Exacto Triplex<sup>?</sup> HIV/HCV/HBsAg rapid test, cross-validated by ELISA tests. Sociodemographic and professional data, the modes of transmission and prevention of HIV and both hepatitis viruses were collected in a standard sheet and analyzed using the Epi-Info software version 7. Results: Pregnant women aged 15 to 24 were the most affected (45.3%);high school girls (46.0%), and pregnant women living in cohabitation (65.3%) were the most represented. Twenty-five (16.7%) worked in the formal sector, 12.7% were unemployed housewives and the remainder in the informal sector. The prevalence of HIV, HBV, and HCV viruses was 11.8%, 21.9% and 22.2%, respectively. The prevalence of co-infections was 8.6% for HIV-HBV, 10.2% for HIV-HCV, 14.7% for HBV-HCV and 6.5% for HIV-HBV-HCV. All positive results and 10% of negative results by the rapid test were confirmed by ELISA tests. The serology of the three viruses costs 39,000 FCFA (60 Euros) by ELISA compared to 10,000 FCFA (15.00 Euros) with Exacto Triplex<sup>?</sup> HIV/HCV/AgHBs (BioSynex, Strasbourg, France). Conclusion: The low level of education and awareness of hepatitis are barriers to development and indicate the importance of improving the literacy rate of women in the Central African Republic (CAR). Likewise, the high prevalence of the three viruses shows the need for the urgent establishment of a national program to combat viral hepatitis in the CAR.
基金the Vicerrectorìa de Investigación y Extension of the Universidad Industrial de Santander,Colombia(grant number 2508)for the financial support of the present work
文摘The present study aims to develop multilayer barrier-bioactive hybrid sol-gel coatings from a mixture of the silane precursors tetraethylorthosilicate(TEOS)and glycidoxypropyltriethoxysilane(GPTMS)deposited on the Elektron 21 magnesium alloy.The purpose of the inner layer(barrier coating)was to provide corrosion protection to the magnesium alloy,whereas the outer layer(bioactive coating)was doped with different Ca and Mg contents to produce a bioactive material.The coatings were characterised using scanning electron microscopy(SEM)and their corrosion behaviour was evaluated by anodic polarisation and electrochemical impedance spectroscopy after immersion in simulated body fluid(SBF)at 37±0.5°C.The experimental results showed that the multilayer coatings increased the corrosion resistance of the alloy up to three orders of magnitude during immersion in SBF solution.On the other hand,the presence of Ca and Mg in the bioactive coating promoted the growth of apatite-like phases.However,an increment of salt content favoured the formation of porous coatings,which allowed the access of the electrolyte to the substrate leading to their rapid deterioration.Despite the latter,this research endorses the premise that the TEOS-GPTMS hybrid system represents a promising alternative to produce bifunctional barrier-bioactive coatings.
文摘Due to metal leaching and poor catalyst stability, the chemical industry's fine chemical and pharmaceutical sectors have been historically reluctant to use supported transition metal catalysts to manufacture fine chemicals and active pharmaceutical ingredients. With the advent of new generation supported metal catalysts and flow chemistry, we argue in this study, this situation is poised to quickly change. Alongside heterogenized metal nanoparticles, both single-site molecular and single-atom catalyst will become ubiquitous. This study offers a critical outlook taking into account both technical and economic aspects.
基金The project “Bosques Andinos” was funding by Helvetas Swiss development organizationdeveloped by Medellín Botanical Garden “Joaquín Antonio Uribe”.
文摘Background:Species turnover(β-diversity)along elevational gradients is one of the most important concepts in plant ecology.However,there is a lack of consensus about the main driving mechanisms of treeβ-diversity at local scales in very diverse ecosystems(e.g.,Andean mountains),as well as how the sampling effect can alterβ-diversity estimations.Recently,it has been hypothesized that patterns of change inβ-diversity at local scales along elevational gradients are driven by sampling effects stemming from differences in the size of the species pool rather than by underlying community assembly mechanisms.Thus,we aim to evaluate the relative extent to which sampling effects,such as species pool size,grain size,and tree size cut-off,determine species sorting,and thus,the variability ofβ-diversity at local scales along elevational gradients in the northwest of Colombia.Results:Using 151-ha permanent plots spread out along a 3000m elevational gradient,we used standardizedβ-deviation to assess the extent to which either sampling effects or the community assembly mechanisms determine the changes in species composition at local scales.Standardizedβ-deviation was measured as the difference between the observed and nullβ-diversity divided by the standard deviation of the nullβ-diversity.We found that the magnitude of change in localβ-deviation along the elevational gradient was significant and dependent on the employed spatial grain size and tree size cut-off.However,β-deviation increased with elevation in all sampling designs,which suggests that underlying community assembly mechanisms play a key role in shaping localβ-diversity along the elevational gradient.Conclusions:Our findings suggest that grain size enlargement and the inclusion of trees with small diameters will improve our ability to quantify the extent to which the community assembly mechanisms shape patterns ofβ-diversity along elevational gradients.Overall,we emphasize the scale-dependent nature of the assessment ofβ-diversity.Likewise,we call for the need of a new generation of enlarged forest inventory plots along gradients of elevation in tropical forests that include small individuals to improve our understanding about the likely response of diversity and function to global change.
基金Colciencias and SUMICOL(Suministros de Colombia S.A.)for their support and financing for this project
文摘This work proposes a soft sensor based on a phenomenological model for online estimation of the density and viscosity of a slurry flowing through a pipe-and-fittings assembly(PFA). The model is developed considering the conservation principle applied to mass and momentum transfer and considering frictional energy losses to include the variables directly affecting slurry properties. A reported proposal for state observers with unknown inputs is used to develop the first block of the observer structure. The second block is constructed with two options for evaluating slurry viscosity, generating two possible estimator structures, which are tested using real data. A comparison between them indicates different uses and capabilities according to available process information.
基金a postdoctorate grant(693118)of Tabriz University of Medical Sciences,Iran for supporting this work.
文摘Experimental mole fraction solubility of lamotrigine(LTG)in ternary aqueous mixtures of two ionic liquids(ILs),1-hexyl and 1-octyl-3-methylimidazolium bromide,[HMIm][Br]and[OMIm][Br]were reported at several temperatures T=(293.15 to 313.15)K.The van’t Hoff and(Jouyban-Acree-van’t Hoff,E-Jouyban-Acree-van’t Hoff,e-NRTL,UNIQUAC and Wilson)models were used to correlate the solubility data.The comparison of the models with temperature and solvent composition dependencies shows that the Wilson model has the minimum ARD which are relatively close to those obtained from Jouyban-Acree-van’t Hoff and E-Jouyban-Acree-van’t Hoff models and maximum ARD belonged to the UNIQUAC model.The order of ARDs for these models is:Wilson b Jouyban-Acree-van’t Hoff,E-Jouyban-Acree-van’t Hoff b e-NRTL b UNIQUAC.Moreover,the apparent thermodynamic functions,Gibbs free energy,enthalpy and entropy of dissolution and mixing were calculated based on the van’t Hoff and Gibbs free energy equations.The strong LTG-ILs interactions and enthalpic contribution of the dissolution process resulted from the calculated thermodynamic functions.
基金supported by the National Nature Science Foun-dation of China(grant No.51905310)Natural Science Founda-tion of Shandong Province(Nos.ZR2020YQ39 and ZR2020ZD05)+2 种基金the Young Scholars Program of Shandong University(grant No.2018WLJH24)and Shandong Medical Products Administration(grant No.SDNMPAFZLX202204)the sup-port from MCIN/AEI/10.13039/501100011033 and FEDER Una Man-era de Hacer Europa,EU(project No.RTI2018-094683-B-C51).
文摘In this work,NiTi samples with different thicknesses(0.15-1.00 mm)were fabricated by laser powder bed fusion(LPBF)under variable scanning speeds(500-1200 mm s^(-1)).The densification behavior,phase transformation behavior,and mechanical properties of the sample with different thicknesses are studied.The results indicate a strong size effect in the LPBF-fabricated NiTi alloy.The decrease of the sample thickness results in(i)the increase of porosity,(ii)the decrease of the number of adhered NiTi powder particles at the surface,(iii)the monotonous decrease of the martensitic transformation temperatures(MTTs),and(iv)the decrease of the shape recovery temperature.The influence of sample thickness on the melt-pool behavior,and thus the microstructure and performance of NiTi alloys are discussed.It is suggested that the melt-pool is deeper and narrower in the thin samples than in the thick samples.We conclude that,apart from the LPBF process conditions,the sample dimensions have also to be considered to fabricate NiTi structures with predictable properties.
