With the pressing concern of the climate change,hydrogen will undoubtedly play an essential role in the future to accelerate the way out from fossil fuel-based economy.In this case,the role of membrane-based separatio...With the pressing concern of the climate change,hydrogen will undoubtedly play an essential role in the future to accelerate the way out from fossil fuel-based economy.In this case,the role of membrane-based separation cannot be neglected since,compared with other conventional process,membrane-based process is more effective and consumes less energy.Regarding this,metal-based membranes,particularly palladium,are usually employed for hydrogen separation because of its high selectivity.However,with the advancement of various microporous materials,the status quo of the metal-based membranes could be challenged since,compared with the metal-based membranes,they could offer better hydrogen separation performance and could also be cheaper to be produced.In this article,the advancement of membranes fabricated from five main microporous materials,namely silica-based membranes,zeolite membranes,carbon-based membranes,metal organic frameworks/covalent organic frameworks(MOF/COF)membranes and microporous polymeric membranes,for hydrogen separation from light gases are extensively discussed.Their performances are then summarized to give further insights regarding the pathway that should be taken to direct the research direction in the future.展开更多
Sea urchin spines were chosen as a model system for biomimetic ceramics obtained using starch-blended slip casting. Porous alumina ceramics with cap-shaped layers with different alternating porosities were found to ha...Sea urchin spines were chosen as a model system for biomimetic ceramics obtained using starch-blended slip casting. Porous alumina ceramics with cap-shaped layers with different alternating porosities were found to have superior fracture behavior under bulk compression compared to ceramics with uniform porosity.They fail in a cascading manner,absorbing high amounts of energy during extended compression paths.The porosity variation in an otherwise single phase material mimicks the architectural microstructure design of sea urchin spines of Heterocentrotus mammillatus,which are promising model materials for impact protection.展开更多
The theory here developed, makes use of the decomposition of matter (mass) in different spatial frequencies k’s using spatial Fourier transforms, and the posterior use of modified inverse Fourier transforms to constr...The theory here developed, makes use of the decomposition of matter (mass) in different spatial frequencies k’s using spatial Fourier transforms, and the posterior use of modified inverse Fourier transforms to construct an accurate description of the classical Newtonian gravitational field. Introducing the concept of quantization of the spatial frequency <em>k</em>, which means allowing only discrete values, such as <em>k<sub>m</sub></em>, 2<em>k<sub>m</sub></em>, 3<em>k<sub>m</sub></em>, leads to the appearance of extra gravitational force regions that occur at distances equally spaced apart in 2π/<em>k<sub>m</sub></em>. These areas of extra gravitational force decrease inscribed in an inverse of the distance envelope (1/<em>r</em>). The value of 2π/<em>k<sub>m</sub></em> can be adjusted to be of the order of kiloparsec (kpc), being this way a plausible explanation for the effect of the dark matter since this causes practically flat rotation curves for most of the galaxies. As these regions of extra gravitational force also have adjacent areas of negative values (repulsive gravitational force), it is possible to show that any mass placed in the gravitational field far from the galaxy center will acquire, on average, a null acceleration, thereby remains the “light push,” or in other words, the “mean luminosity density” between galaxies as an explanation for the accelerating expansion of the universe, today being considered mainly due to dark energy. Along with the article, it is showed that the effect of light push is sufficient to explain the expansion of the universe. The present work also explains the nonlinear behavior of gravitational fields near massive objects such as blackholes, not contradicting the theory of general relativity, instead giving a complementary description of how black holes work, even describing the gravitational field internally to it, which is not available in the GR theory.展开更多
The SONE oil/water was prepared using the pseudo-ternary phase diagram, using a low energy method with phase inversion by changing the composition. In order to optimize the preparation of SONE, three speeds were used ...The SONE oil/water was prepared using the pseudo-ternary phase diagram, using a low energy method with phase inversion by changing the composition. In order to optimize the preparation of SONE, three speeds were used in the agitator arm and two different rods. The particle size and polydispersity index were determined by Dynamic Light Scattering (DLS) and the stability test by the freeze-thaw cycle. Angiogenesis in chicken embryo egg chorioallantoic membrane and zebrafish (<em>Danio rerio</em>) embryotoxicity was performed. The lower stirring speed and propeller shaft induced smaller particle size (550.2 nm). Regarding angiogenesis, there was a statistically significant difference for all the evaluated parameters (length, caliber, junctions, and number of blood vessel complexes) and the result was higher in SONE when compared to the inhibition control (Dexamethasone), but lower than the induction control (Regederm<span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;"><sup>®</sup></span>) and there was no statistically significant difference between SONE and distilled water. It was observed that the exposure of the zebrafish embryos to SONE caused an increase in the mortality rate dependent on time and concentration. The LC<sub>50</sub> for SONE decreased statistically with increasing exposure (p-value = 0.046). Heart rate decreased significantly with increasing concentration at all exposure times (p-value < 0.05), as a result of progressive embryo mortality. The hatching rate was late until the concentration of 0.0193 mg/mL and no hatching rate was verified from that concentration. Exposure of zebrafish embryos to different concentrations of SONE induced malformations such as spinal changes, pericardial edema and yolk sac edema, but there was no significant difference in the malformation rate of embryos exposed to SONE when compared to the control group. The SONE produced remained stable in the freeze-thaw cycle, with changes only in pH. Despite the low results for embryotoxicity, further studies are needed, aiming at the ideal formulation for angiogenesis purposes.展开更多
xThis study has as its objective to collaborate with the expansion in the market of electric energy in rural areas,offering as such an innovative prospect to the solution of associated problems through use of the asym...xThis study has as its objective to collaborate with the expansion in the market of electric energy in rural areas,offering as such an innovative prospect to the solution of associated problems through use of the asymmetric three-phase induction motor,supplied by a single-phase source.In this system,capacitor switching is applied during operation,while theoretical and practical results are presented for the application of this switching in a three-phase asymmetric induction motor of 20 hp.展开更多
Nowadays,globalization has become essential,and interconnection between people and cargo has become necessary due to international trade and investment.In this context,aviation is an important modal because of its eff...Nowadays,globalization has become essential,and interconnection between people and cargo has become necessary due to international trade and investment.In this context,aviation is an important modal because of its efficiency in security,range,and speed;however,the aerodrome infrastructure capacity is not always sized according to the demand and safety regulations required during operations.The number of runway occurrences in Brazil increased considerably since 2011.These occurrences are consequences of several contributing factors,of which runway conditions and airport infrastructure can be considered the most important;however,the quality of runways and the flight safety they provide can’t be quantified through direct statistics.Adhering to a high standard of airfield quality while also knowing airport infrastructure,a study that applies an evaluation of the Pavement Condition Index(PCI)methodology has been developed.First,the airfield pavement at a military base was analyzed and later compared to the results found in a civil airfield study done by another author.The methods used to identify distress in the pavement’s surface were based on ASTM D 5340-12,as are PCI calculations.Secondly,the system was infused into PAVEAIR-FAA(Federal Aviation Administration)to apply an airport management method at a military base to compare the results obtained by other authors for a civil airfield study,where it was intended to analyze the performance characteristics of the runway for each type use.Subsequently,one can obtain subsidies of decisions for the optimization of resources used in airfield maintenance and rehabilitation,and increase operational safety.展开更多
Silica gel (SG) was synthesized via acidification of sodium silicate solution then doped with Fˉ or Zr(IV) in molar ratios of F/Si 3/100, and Zr/Si 0.75/100 and 3.75/100 and sintered at 500°C, 800°C and 100...Silica gel (SG) was synthesized via acidification of sodium silicate solution then doped with Fˉ or Zr(IV) in molar ratios of F/Si 3/100, and Zr/Si 0.75/100 and 3.75/100 and sintered at 500°C, 800°C and 1000°C. The samples were investigated by X-ray diffractometry, infrared absorption and Raman spectra, surface area measurement, and inductively coupled plasma-optical emission spectrometry-monitored silica hydrolysis. All samples are mesoporous with BET surface areas 181.5 - 523.9 m2·gˉ1. The surface area of the silica samples decreases as the sintering temperature increases. The hydrolysis process of silica decreases as the sintering temperature increases and as the surface area decreases. The pH and the type of buffer solution affect the hydrolysis of silica samples due to a SN2 reaction mechanism favored in basic media using ammonia buffer. Zr(IV) increases the stability of silica samples against the hydrolysis as confirmed by the structural investigation, surface area and silica hydrolysis. Fˉ observably decreases the silica hydrolysis process when presenting on the surface of SG.展开更多
Functional,porous metal-organic frameworks(MOFs)have attracted much attention as a very flexible class of crystalline,porous materials.For more advanced applications that exploit photophysical properties,the fabricati...Functional,porous metal-organic frameworks(MOFs)have attracted much attention as a very flexible class of crystalline,porous materials.For more advanced applications that exploit photophysical properties,the fabrication of hierarchical assemblies,including the creation of MOF/MOF heterointerfaces,is important.For the manufacturing of superstructures with length scales well beyond that of the MOF pore size,layer-by-layer(Ibl)methods are particularly attractive.These allow the isoreticular approach to be extended to superstructures with micrometer length scales,a range that is not accessible using conventional MOF design.The Ibl approach further substantially extends the compositional diversity in MOFs.At the same time,the favorable elastic properties of MOFs allow for heteroepitaxial growth,even in the case of lattice misfits as large as 20%.While the MOF-on-MOF approach to designing multicomponent superstructures with synergistic multifunctionality can also be realized with sophisticated solvothermal synthesis schemes,the Ibl(or liquid-phase epitaxy)approach carries substantial advantages,in particular when it comes to the integration of such MOF superstructures into optical or electronic devices.While the structure vertical to the substrate can be adjusted using the Ibl method,photolithographic methods can be used for lateral structuring.In this review,we will discuss the Ibl liquid-phase epitaxy approach to growing surface-anchored MOF thins films(SURMOFs)as well as other relevant one-pot synthesis methods for constructing such hierarchically designed structures and their emerging applications.展开更多
Oriented metal-organic framework(MOF)films are attracting great attention due to their fascinating physicochemical properties and unique functionalities.Here,we report an[110]-oriented biomolecularγ-cyclodextrin(γCD...Oriented metal-organic framework(MOF)films are attracting great attention due to their fascinating physicochemical properties and unique functionalities.Here,we report an[110]-oriented biomolecularγ-cyclodextrin(γCD)MOF film with arrayed CD channels running perpendicular to the substrate surface.This sophisticated architecturewas realized by combining liquid phase epitaxial layer-by-layer(lbl)methods with aγCD-based thiol self-assembled monolayer(SAM)functionalized surface.This first demonstration of the lbl method for MOF growth from aqueous conditions yielded oriented,highly homogeneous,and chiralγCD-SURMOFs(surfacecoordinated MOFs)with tunable thickness.Using a quartz crystal microbalance(QCM)to monitor adsorption of biomolecules,we demonstrated thatγCD-SURMOF provides highly-efficient recognition of tripeptide enantiomers(Tyr-(L-Ala)-Phe vs Tyr-(D-Ala)-Phe),clearly outperformingγCD(SH)_(8) SAMs as well as polycrystalline,mixed-orientationsγCDMOF film.The presence of well-alignedγCD-channels enables highly efficient transport channels with large adsorption capacity and fast loading,along with high enantioselectivity.In addition,the fast and highly specific loading rates allow for the realization of highly specific sensors for biomolecules with short response times.展开更多
基金funding from the Alexander von Humboldt Postdoctoral Fellowship(Ref-3.3-GBR-1219268-HFST-P)。
文摘With the pressing concern of the climate change,hydrogen will undoubtedly play an essential role in the future to accelerate the way out from fossil fuel-based economy.In this case,the role of membrane-based separation cannot be neglected since,compared with other conventional process,membrane-based process is more effective and consumes less energy.Regarding this,metal-based membranes,particularly palladium,are usually employed for hydrogen separation because of its high selectivity.However,with the advancement of various microporous materials,the status quo of the metal-based membranes could be challenged since,compared with the metal-based membranes,they could offer better hydrogen separation performance and could also be cheaper to be produced.In this article,the advancement of membranes fabricated from five main microporous materials,namely silica-based membranes,zeolite membranes,carbon-based membranes,metal organic frameworks/covalent organic frameworks(MOF/COF)membranes and microporous polymeric membranes,for hydrogen separation from light gases are extensively discussed.Their performances are then summarized to give further insights regarding the pathway that should be taken to direct the research direction in the future.
基金funded by European sources within the ERASMUS-SOCRATES program
文摘Sea urchin spines were chosen as a model system for biomimetic ceramics obtained using starch-blended slip casting. Porous alumina ceramics with cap-shaped layers with different alternating porosities were found to have superior fracture behavior under bulk compression compared to ceramics with uniform porosity.They fail in a cascading manner,absorbing high amounts of energy during extended compression paths.The porosity variation in an otherwise single phase material mimicks the architectural microstructure design of sea urchin spines of Heterocentrotus mammillatus,which are promising model materials for impact protection.
文摘The theory here developed, makes use of the decomposition of matter (mass) in different spatial frequencies k’s using spatial Fourier transforms, and the posterior use of modified inverse Fourier transforms to construct an accurate description of the classical Newtonian gravitational field. Introducing the concept of quantization of the spatial frequency <em>k</em>, which means allowing only discrete values, such as <em>k<sub>m</sub></em>, 2<em>k<sub>m</sub></em>, 3<em>k<sub>m</sub></em>, leads to the appearance of extra gravitational force regions that occur at distances equally spaced apart in 2π/<em>k<sub>m</sub></em>. These areas of extra gravitational force decrease inscribed in an inverse of the distance envelope (1/<em>r</em>). The value of 2π/<em>k<sub>m</sub></em> can be adjusted to be of the order of kiloparsec (kpc), being this way a plausible explanation for the effect of the dark matter since this causes practically flat rotation curves for most of the galaxies. As these regions of extra gravitational force also have adjacent areas of negative values (repulsive gravitational force), it is possible to show that any mass placed in the gravitational field far from the galaxy center will acquire, on average, a null acceleration, thereby remains the “light push,” or in other words, the “mean luminosity density” between galaxies as an explanation for the accelerating expansion of the universe, today being considered mainly due to dark energy. Along with the article, it is showed that the effect of light push is sufficient to explain the expansion of the universe. The present work also explains the nonlinear behavior of gravitational fields near massive objects such as blackholes, not contradicting the theory of general relativity, instead giving a complementary description of how black holes work, even describing the gravitational field internally to it, which is not available in the GR theory.
文摘The SONE oil/water was prepared using the pseudo-ternary phase diagram, using a low energy method with phase inversion by changing the composition. In order to optimize the preparation of SONE, three speeds were used in the agitator arm and two different rods. The particle size and polydispersity index were determined by Dynamic Light Scattering (DLS) and the stability test by the freeze-thaw cycle. Angiogenesis in chicken embryo egg chorioallantoic membrane and zebrafish (<em>Danio rerio</em>) embryotoxicity was performed. The lower stirring speed and propeller shaft induced smaller particle size (550.2 nm). Regarding angiogenesis, there was a statistically significant difference for all the evaluated parameters (length, caliber, junctions, and number of blood vessel complexes) and the result was higher in SONE when compared to the inhibition control (Dexamethasone), but lower than the induction control (Regederm<span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;"><sup>®</sup></span>) and there was no statistically significant difference between SONE and distilled water. It was observed that the exposure of the zebrafish embryos to SONE caused an increase in the mortality rate dependent on time and concentration. The LC<sub>50</sub> for SONE decreased statistically with increasing exposure (p-value = 0.046). Heart rate decreased significantly with increasing concentration at all exposure times (p-value < 0.05), as a result of progressive embryo mortality. The hatching rate was late until the concentration of 0.0193 mg/mL and no hatching rate was verified from that concentration. Exposure of zebrafish embryos to different concentrations of SONE induced malformations such as spinal changes, pericardial edema and yolk sac edema, but there was no significant difference in the malformation rate of embryos exposed to SONE when compared to the control group. The SONE produced remained stable in the freeze-thaw cycle, with changes only in pH. Despite the low results for embryotoxicity, further studies are needed, aiming at the ideal formulation for angiogenesis purposes.
文摘xThis study has as its objective to collaborate with the expansion in the market of electric energy in rural areas,offering as such an innovative prospect to the solution of associated problems through use of the asymmetric three-phase induction motor,supplied by a single-phase source.In this system,capacitor switching is applied during operation,while theoretical and practical results are presented for the application of this switching in a three-phase asymmetric induction motor of 20 hp.
文摘Nowadays,globalization has become essential,and interconnection between people and cargo has become necessary due to international trade and investment.In this context,aviation is an important modal because of its efficiency in security,range,and speed;however,the aerodrome infrastructure capacity is not always sized according to the demand and safety regulations required during operations.The number of runway occurrences in Brazil increased considerably since 2011.These occurrences are consequences of several contributing factors,of which runway conditions and airport infrastructure can be considered the most important;however,the quality of runways and the flight safety they provide can’t be quantified through direct statistics.Adhering to a high standard of airfield quality while also knowing airport infrastructure,a study that applies an evaluation of the Pavement Condition Index(PCI)methodology has been developed.First,the airfield pavement at a military base was analyzed and later compared to the results found in a civil airfield study done by another author.The methods used to identify distress in the pavement’s surface were based on ASTM D 5340-12,as are PCI calculations.Secondly,the system was infused into PAVEAIR-FAA(Federal Aviation Administration)to apply an airport management method at a military base to compare the results obtained by other authors for a civil airfield study,where it was intended to analyze the performance characteristics of the runway for each type use.Subsequently,one can obtain subsidies of decisions for the optimization of resources used in airfield maintenance and rehabilitation,and increase operational safety.
基金partly funded by the Alexander von Humboldt foundation,Germany,in the frame of a fellowship award.
文摘Silica gel (SG) was synthesized via acidification of sodium silicate solution then doped with Fˉ or Zr(IV) in molar ratios of F/Si 3/100, and Zr/Si 0.75/100 and 3.75/100 and sintered at 500°C, 800°C and 1000°C. The samples were investigated by X-ray diffractometry, infrared absorption and Raman spectra, surface area measurement, and inductively coupled plasma-optical emission spectrometry-monitored silica hydrolysis. All samples are mesoporous with BET surface areas 181.5 - 523.9 m2·gˉ1. The surface area of the silica samples decreases as the sintering temperature increases. The hydrolysis process of silica decreases as the sintering temperature increases and as the surface area decreases. The pH and the type of buffer solution affect the hydrolysis of silica samples due to a SN2 reaction mechanism favored in basic media using ammonia buffer. Zr(IV) increases the stability of silica samples against the hydrolysis as confirmed by the structural investigation, surface area and silica hydrolysis. Fˉ observably decreases the silica hydrolysis process when presenting on the surface of SG.
基金Deutsche Forschungsgemeinschaft(DFG,Germ an Research Foundation)under Germany’s Excellence Strategy-2082/1-390761711 and SPP 1928 wCOORNETS.M We thank Xiaojing Liu for comments on the manuscript.
文摘Functional,porous metal-organic frameworks(MOFs)have attracted much attention as a very flexible class of crystalline,porous materials.For more advanced applications that exploit photophysical properties,the fabrication of hierarchical assemblies,including the creation of MOF/MOF heterointerfaces,is important.For the manufacturing of superstructures with length scales well beyond that of the MOF pore size,layer-by-layer(Ibl)methods are particularly attractive.These allow the isoreticular approach to be extended to superstructures with micrometer length scales,a range that is not accessible using conventional MOF design.The Ibl approach further substantially extends the compositional diversity in MOFs.At the same time,the favorable elastic properties of MOFs allow for heteroepitaxial growth,even in the case of lattice misfits as large as 20%.While the MOF-on-MOF approach to designing multicomponent superstructures with synergistic multifunctionality can also be realized with sophisticated solvothermal synthesis schemes,the Ibl(or liquid-phase epitaxy)approach carries substantial advantages,in particular when it comes to the integration of such MOF superstructures into optical or electronic devices.While the structure vertical to the substrate can be adjusted using the Ibl method,photolithographic methods can be used for lateral structuring.In this review,we will discuss the Ibl liquid-phase epitaxy approach to growing surface-anchored MOF thins films(SURMOFs)as well as other relevant one-pot synthesis methods for constructing such hierarchically designed structures and their emerging applications.
基金This work was supported by the National Natural Science Foundation of China(grant nos.21872148 and 92161105)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(grant no.2018339)+1 种基金Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China(grant no.2021ZR131)C.W.acknowledges support from the Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)under the Germany Excellence Strategy via the Excellence Cluster 3D Matter Made to Order(grant no.EXC-2082/1-390761711).
文摘Oriented metal-organic framework(MOF)films are attracting great attention due to their fascinating physicochemical properties and unique functionalities.Here,we report an[110]-oriented biomolecularγ-cyclodextrin(γCD)MOF film with arrayed CD channels running perpendicular to the substrate surface.This sophisticated architecturewas realized by combining liquid phase epitaxial layer-by-layer(lbl)methods with aγCD-based thiol self-assembled monolayer(SAM)functionalized surface.This first demonstration of the lbl method for MOF growth from aqueous conditions yielded oriented,highly homogeneous,and chiralγCD-SURMOFs(surfacecoordinated MOFs)with tunable thickness.Using a quartz crystal microbalance(QCM)to monitor adsorption of biomolecules,we demonstrated thatγCD-SURMOF provides highly-efficient recognition of tripeptide enantiomers(Tyr-(L-Ala)-Phe vs Tyr-(D-Ala)-Phe),clearly outperformingγCD(SH)_(8) SAMs as well as polycrystalline,mixed-orientationsγCDMOF film.The presence of well-alignedγCD-channels enables highly efficient transport channels with large adsorption capacity and fast loading,along with high enantioselectivity.In addition,the fast and highly specific loading rates allow for the realization of highly specific sensors for biomolecules with short response times.
