Electron beam melting(EBM) process is an additive manufacturing process largely used to produce complex metallic components made of high-performance materials for aerospace and medical applications.Especially,lattice ...Electron beam melting(EBM) process is an additive manufacturing process largely used to produce complex metallic components made of high-performance materials for aerospace and medical applications.Especially,lattice structures made by Ti-6A1-4V have represented a hot topic for the industrial sectors because of having a great potential to combine lower weights and higher performances that can also be tailored by subsequent heat treatments.However,the little knowledge about the mechanical behaviour of the lattice structures is limiting their applications.The present work aims to provide a comprehensive review of the studies on the mechanical behaviour of the lattice structures made of Ti-6A1-4V.The main steps to produce an EBM part were considered as guidelines to review the literature on the lattice performance:(1) design,(2) process and(3) post-heat treatment.Thereafter,the correlation between the geometrical features of the lattice structure and their mechanical behaviour is discussed.In addition,the correlation among the mechanical performance of the lattice structures and the process precision,surface roughness and working temperature are also reviewed.An investigation on the studies about the properties of heat-treated lattice structure is also conducted.展开更多
In this study,the mechanical properties of glass scaffolds manufactured by robocasting are investigated through micro computed tomography(/x-CT)based finite element modeling.The scaffolds are obtained by printing fibe...In this study,the mechanical properties of glass scaffolds manufactured by robocasting are investigated through micro computed tomography(/x-CT)based finite element modeling.The scaffolds are obtained by printing fibers along two perpendicular directions on parallel layers with a 90°tilting between two adjacent layers.A parametric study is first presented with the purpose to assess the effect of the major design parameters on the elastic and strength properties of the scaffold;the mechanical properties of the 3D printed scaffolds are eventually estimated by using the\i-CT data with the aim of assessing the effect of defects on the final geometry which are intrinsic in the manufacturing process.The macroscopic elastic modulus and strength of the scaffold are determined by simulating a uniaxial compressive test along the direction which is perpendicular to the layers of the printed fibers.An iterative approach has been used in order to determine the scaffold strength.A partial validation of the computational model has been obtained through comparison of the computed results with experimental values presented in[10]on a ceramic scaffold having the same geometry.All the results have been presented as non-dimensional values.The finite element analyses have shown which of the selected design parameters have the major effect on the stiffness and strength,being the porosity and fiber shifting between adjacent layers the most important ones.The analyses carried out on the basis of the/x-C7 data have shown elastic modulus and strength which are consistent with that found on ideal geometry at similar macroscopic porosity.展开更多
An historical collection of more than one hundred samples of minerals and ore, used in the second half of the XVIII century was found and acquired during Munich Mineralientage 2014. The samples contained in numbered g...An historical collection of more than one hundred samples of minerals and ore, used in the second half of the XVIII century was found and acquired during Munich Mineralientage 2014. The samples contained in numbered glass vials but lacking description, were prepared for teaching purpose about determinative mineralogy and ore recognition. All samples were analysed and identified. The identification effort drove the authors along a historical excursus about the didactics of mineralogy and the dry method analysis, nowadays neglected.展开更多
Ti-6Al-4Zr-2Sn-6Mo alloy is one of the most recent titanium alloys processed using powder bed fusion-laser beam(PBF-LB)technology.This alloy has the potential to replace Ti-6Al-4V in automotive and aerospace applicati...Ti-6Al-4Zr-2Sn-6Mo alloy is one of the most recent titanium alloys processed using powder bed fusion-laser beam(PBF-LB)technology.This alloy has the potential to replace Ti-6Al-4V in automotive and aerospace applications,given its superior mechanical properties,which are approximately 10%higher in terms of ultimate tensile strength(UTS)and yield strength after appropriate heat treatment.In as-built conditions,the alloy is characterized by the presence of soft orthorhombicα″martensite,necessitating a postprocessing heat treatment to decompose this phase and enhance the mechanical properties of the alloy.Usually,PBFed Ti6246 components undergo an annealing process that transforms theα″martensite into anα-βlamellar microstructure.The primary objective of this research was to develop a solution treatment and aging(STA)heat treatment tailored to the unique microstructure produced by the additive manufacturing process to achieve an ultrafine bilamellar microstructure reinforced by precipitation hardening.This study investigated the effects of various solution temperatures in theα-βfield(ranging from 800 to 875℃),cooling media(air and water),and aging time to determine the optimal heat treatment parameters for achieving the desired bilamellar microstructure.For each heat treatment condition,differentα-βmicrostructures were found,varying in terms of theα/βratio and the size of the primaryα-phase lamellae.Particular attention was given to how these factors were influenced by increases in solution temperature and how microhardness correlated with the percentage of the metastableβphase present after quenching.Tensile tests were performed on samples subjected to the most promising heat treatment parameters.A comparison with literature data revealed that the optimized STA treatment enhanced hardness and UTS by13%and 23%,respectively,compared with those of the annealed alloy.Fracture surface analyses were conducted to investigate fracture mechanisms.展开更多
It is well known that the safety and efficacy profile of an inhaled cortocosteroid(ICS) is influenced by the pharmacokinetic properties and associated pharmacodynamic effects of the drug. Freely circulating,protein un...It is well known that the safety and efficacy profile of an inhaled cortocosteroid(ICS) is influenced by the pharmacokinetic properties and associated pharmacodynamic effects of the drug. Freely circulating,protein unbound, and active ICS can cause systemic adverse effects. Therefore, a detailed investigation of drug-protein interaction could be of great interest to understand the pharmacokinetic behaviour of corticosteroids and for the design of new analogues with effective pharmacological properties. In the present work, the interaction between some corticosteroids and human serum albumin(HSA) has been studied by spectroscopic approaches. UV–Vis spectroscopy confirmed that all the investigated corticosteroids can bind to HSA forming a protein-drug complex. The intrinsic fluorescence of HSA was quenched by all the investigated drugs, which was rationalized in terms of a static quenching mechanism. The thermodynamic parameters determined by the Van't Hoff analysis of the binding constants(negative ΔH and ΔS values) clearly indicate thathydrogen bonds and van der Waals forces play a major role in the binding process between albumin and betamethasone, flunisolide and prednisolone, while hydrophobic forces may play a major role in stabilizing albumin-triamcinolone complexes.展开更多
Sodium potassium niobate (KNN) (K0.5Na0.5NbO3) nanopowder with a mean particle size of about 20 - 30 nm was synthesized by wet chemical route using Nb2O5 as Nb source. A solution of K, Na and Nb cations was prepared, ...Sodium potassium niobate (KNN) (K0.5Na0.5NbO3) nanopowder with a mean particle size of about 20 - 30 nm was synthesized by wet chemical route using Nb2O5 as Nb source. A solution of K, Na and Nb cations was prepared, which resulted in a clear gel after the thermal treatment. Phase analysis, microstructure and morphology of the powder were determined by X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Field Emission Scanning Electron Microscopy (FESEM). The obtained gel was first analyzed by Thermo Gravimetric Analyzer (TGA) and Differential Scanning Calorimetry (DSC), and then calcined at different temperatures of 400℃, 500℃, 600℃ and 700℃. The X-Ray Diffraction (XRD) patterns of the synthesized samples confirmed the formation of the orthorhombic crystal phase of K0.5Na0.5NbO3 at 500?C, a temperature significantly lower than that typically used in the conventional mixed oxide route. The process developed in this work is convenient to realize the mass production of KNN nanopowders at low cost and suitable for various industrial applications.展开更多
In the quest for the development of safer lithium-metal batteries(LMBs),the integration of inorganic fillers and ionic liquids into polymer matrices has emerged as a promising strategy to enhance safety,ionic conducti...In the quest for the development of safer lithium-metal batteries(LMBs),the integration of inorganic fillers and ionic liquids into polymer matrices has emerged as a promising strategy to enhance safety,ionic conductivity and battery performance.This study introduces a novel composite ionogel(IG)synthesized through a facile one-pot method,incorporating butyl methacrylate(BMA)and poly(ethylene glycol)diacrylate(PEGDA)with the ionic liquid 1-butyl-1-methylpyrrolidinium bis(fluorosulfonyl)imide(PYR_(14)FSI)and garnet Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)(LLZTO)nanoparticles.A distinctive feature of the approach is the use of an organosilane functionalization of the LLZTO nanoparticles,which ensures their full integration into the polymer matrix during free-radical polymerization.Moreover,this method effectively eliminates the Li_(2)CO_(3)passivation layer that typically forms on the surface of the LLZTO nanoparticles,thus,further contributing to an enhanced performance.As a result,a LMB with the functionalized LLZTO IG electrolyte delivered more than 160 mA h g^(−1)with a very good capacity retention of 97.7%after 400 cycles in Li|IG|LFP cells.展开更多
In the present work, carbon nano/microparticles obtained by controlled pyrolysis of peanut （PS） and hazelnut （HS） shells are presented. These materials were characterized by Raman spectroscopy and field emissionsc...In the present work, carbon nano/microparticles obtained by controlled pyrolysis of peanut （PS） and hazelnut （HS） shells are presented. These materials were characterized by Raman spectroscopy and field emissionscanning electron microscopy （FE-SEM）. When added to cement paste, up to 1 wt%, these materials led to an increase of the cement matrix flexural strength and of toughness. Moreover, with respect to plain cement, the total increase in electromagnetic radiation shielding effect when adding 0.5 wt% of PS or HS in cement composites is much higher in comparison to the ones reported in the literature for CNTs used in the same content.展开更多
From experime nts, the influe nee of the physical characteristics of different bin ary mixtures of solids on the spouting regime of a pyramidal square-based spouted bed reactor is assessed. The applied methodology per...From experime nts, the influe nee of the physical characteristics of different bin ary mixtures of solids on the spouting regime of a pyramidal square-based spouted bed reactor is assessed. The applied methodology permits a more precise evaluation of the effects of the tested variables (diameter, density, sphericity) on the response variables (minimum air flows at which spouting begins and at which to maintain spouting con ditions). The associated pressure drops along the bed of particles a nd the height of the formed fountai n are analysed in each case. During the initial stages of fluidisation, binary mixtures containing different density ratios show dead zones. Segregation becomes more evident at large-size and high-density ratios. The lack of sphericity was found to be the main reason leading to blocking, channelling, and start-up problems when system failures occur. Nevertheless, the extent of segregation in all cases decreases with increasing the spouting velocity. In addition, a computational fluid dynamic model based on the discrete element method, previously validated for a single solid bed, is proposed as a tool to predict and evaluate potential segregation phenomena in binary mixtures. This model reproduced with high accuracy the encountered segregation phenomena. Its use may help define the technical limts inherent in the pyramidal spouted bed reactor.展开更多
In many optical applications,there is an increasing need for dynamically tunable optical elements that are able to shape the wavefront of light‘on demand’.In this work,an elastomeric easy-to-fabricate optical elemen...In many optical applications,there is an increasing need for dynamically tunable optical elements that are able to shape the wavefront of light‘on demand’.In this work,an elastomeric easy-to-fabricate optical element whose transmission functions can be reversibly phase configured by visible light is demonstrated.The light responsivity of proper azopolymers incorporated within an elastomeric matrix is exploited to induce a light-controlled graded refractive index(GRIN)distribution within the bulk compound.The induced refractive index distribution is continuous and conformal to the intensity profile of the illumination at moderate power.A 100mW doubled-frequency Nd:YAG Gaussian beam focused to a 650μm waist is shown to induce a maximum relative refractive index change of~0.4%in the elastomeric matrix,with an approximately parabolic profile.The restoring characteristics of the elastomeric matrix enable full recovery of the initial homogeneous refractive index distribution within a few seconds when the incident laser is switched off.As an exemplary application,the configurable GRIN element is used in a microscope-based imaging system for light control of the effective focal length.展开更多
文摘Electron beam melting(EBM) process is an additive manufacturing process largely used to produce complex metallic components made of high-performance materials for aerospace and medical applications.Especially,lattice structures made by Ti-6A1-4V have represented a hot topic for the industrial sectors because of having a great potential to combine lower weights and higher performances that can also be tailored by subsequent heat treatments.However,the little knowledge about the mechanical behaviour of the lattice structures is limiting their applications.The present work aims to provide a comprehensive review of the studies on the mechanical behaviour of the lattice structures made of Ti-6A1-4V.The main steps to produce an EBM part were considered as guidelines to review the literature on the lattice performance:(1) design,(2) process and(3) post-heat treatment.Thereafter,the correlation between the geometrical features of the lattice structure and their mechanical behaviour is discussed.In addition,the correlation among the mechanical performance of the lattice structures and the process precision,surface roughness and working temperature are also reviewed.An investigation on the studies about the properties of heat-treated lattice structure is also conducted.
文摘In this study,the mechanical properties of glass scaffolds manufactured by robocasting are investigated through micro computed tomography(/x-CT)based finite element modeling.The scaffolds are obtained by printing fibers along two perpendicular directions on parallel layers with a 90°tilting between two adjacent layers.A parametric study is first presented with the purpose to assess the effect of the major design parameters on the elastic and strength properties of the scaffold;the mechanical properties of the 3D printed scaffolds are eventually estimated by using the\i-CT data with the aim of assessing the effect of defects on the final geometry which are intrinsic in the manufacturing process.The macroscopic elastic modulus and strength of the scaffold are determined by simulating a uniaxial compressive test along the direction which is perpendicular to the layers of the printed fibers.An iterative approach has been used in order to determine the scaffold strength.A partial validation of the computational model has been obtained through comparison of the computed results with experimental values presented in[10]on a ceramic scaffold having the same geometry.All the results have been presented as non-dimensional values.The finite element analyses have shown which of the selected design parameters have the major effect on the stiffness and strength,being the porosity and fiber shifting between adjacent layers the most important ones.The analyses carried out on the basis of the/x-C7 data have shown elastic modulus and strength which are consistent with that found on ideal geometry at similar macroscopic porosity.
文摘An historical collection of more than one hundred samples of minerals and ore, used in the second half of the XVIII century was found and acquired during Munich Mineralientage 2014. The samples contained in numbered glass vials but lacking description, were prepared for teaching purpose about determinative mineralogy and ore recognition. All samples were analysed and identified. The identification effort drove the authors along a historical excursus about the didactics of mineralogy and the dry method analysis, nowadays neglected.
基金financed by the European Union-Next Generation EU(National Sustainable Mobility Center CN00000023,Italian Ministry of University and Research Decree n.1033-17/06/2022,Spoke 11-Innovative Materials&Lightweighting)。
文摘Ti-6Al-4Zr-2Sn-6Mo alloy is one of the most recent titanium alloys processed using powder bed fusion-laser beam(PBF-LB)technology.This alloy has the potential to replace Ti-6Al-4V in automotive and aerospace applications,given its superior mechanical properties,which are approximately 10%higher in terms of ultimate tensile strength(UTS)and yield strength after appropriate heat treatment.In as-built conditions,the alloy is characterized by the presence of soft orthorhombicα″martensite,necessitating a postprocessing heat treatment to decompose this phase and enhance the mechanical properties of the alloy.Usually,PBFed Ti6246 components undergo an annealing process that transforms theα″martensite into anα-βlamellar microstructure.The primary objective of this research was to develop a solution treatment and aging(STA)heat treatment tailored to the unique microstructure produced by the additive manufacturing process to achieve an ultrafine bilamellar microstructure reinforced by precipitation hardening.This study investigated the effects of various solution temperatures in theα-βfield(ranging from 800 to 875℃),cooling media(air and water),and aging time to determine the optimal heat treatment parameters for achieving the desired bilamellar microstructure.For each heat treatment condition,differentα-βmicrostructures were found,varying in terms of theα/βratio and the size of the primaryα-phase lamellae.Particular attention was given to how these factors were influenced by increases in solution temperature and how microhardness correlated with the percentage of the metastableβphase present after quenching.Tensile tests were performed on samples subjected to the most promising heat treatment parameters.A comparison with literature data revealed that the optimized STA treatment enhanced hardness and UTS by13%and 23%,respectively,compared with those of the annealed alloy.Fracture surface analyses were conducted to investigate fracture mechanisms.
基金supported by a grant from the University of Torino(Ricerca Locale ex-60%,Bando 2015)
文摘It is well known that the safety and efficacy profile of an inhaled cortocosteroid(ICS) is influenced by the pharmacokinetic properties and associated pharmacodynamic effects of the drug. Freely circulating,protein unbound, and active ICS can cause systemic adverse effects. Therefore, a detailed investigation of drug-protein interaction could be of great interest to understand the pharmacokinetic behaviour of corticosteroids and for the design of new analogues with effective pharmacological properties. In the present work, the interaction between some corticosteroids and human serum albumin(HSA) has been studied by spectroscopic approaches. UV–Vis spectroscopy confirmed that all the investigated corticosteroids can bind to HSA forming a protein-drug complex. The intrinsic fluorescence of HSA was quenched by all the investigated drugs, which was rationalized in terms of a static quenching mechanism. The thermodynamic parameters determined by the Van't Hoff analysis of the binding constants(negative ΔH and ΔS values) clearly indicate thathydrogen bonds and van der Waals forces play a major role in the binding process between albumin and betamethasone, flunisolide and prednisolone, while hydrophobic forces may play a major role in stabilizing albumin-triamcinolone complexes.
文摘Sodium potassium niobate (KNN) (K0.5Na0.5NbO3) nanopowder with a mean particle size of about 20 - 30 nm was synthesized by wet chemical route using Nb2O5 as Nb source. A solution of K, Na and Nb cations was prepared, which resulted in a clear gel after the thermal treatment. Phase analysis, microstructure and morphology of the powder were determined by X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Field Emission Scanning Electron Microscopy (FESEM). The obtained gel was first analyzed by Thermo Gravimetric Analyzer (TGA) and Differential Scanning Calorimetry (DSC), and then calcined at different temperatures of 400℃, 500℃, 600℃ and 700℃. The X-Ray Diffraction (XRD) patterns of the synthesized samples confirmed the formation of the orthorhombic crystal phase of K0.5Na0.5NbO3 at 500?C, a temperature significantly lower than that typically used in the conventional mixed oxide route. The process developed in this work is convenient to realize the mass production of KNN nanopowders at low cost and suitable for various industrial applications.
基金the German Federal Ministry for Education and Research(BMBF)for financial support within the FB2-Hybrid project(03XP0428B)Moreover,D.Bresser and T.Diemant would like to acknowledge financial support from the Helmholtz Association.
文摘In the quest for the development of safer lithium-metal batteries(LMBs),the integration of inorganic fillers and ionic liquids into polymer matrices has emerged as a promising strategy to enhance safety,ionic conductivity and battery performance.This study introduces a novel composite ionogel(IG)synthesized through a facile one-pot method,incorporating butyl methacrylate(BMA)and poly(ethylene glycol)diacrylate(PEGDA)with the ionic liquid 1-butyl-1-methylpyrrolidinium bis(fluorosulfonyl)imide(PYR_(14)FSI)and garnet Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)(LLZTO)nanoparticles.A distinctive feature of the approach is the use of an organosilane functionalization of the LLZTO nanoparticles,which ensures their full integration into the polymer matrix during free-radical polymerization.Moreover,this method effectively eliminates the Li_(2)CO_(3)passivation layer that typically forms on the surface of the LLZTO nanoparticles,thus,further contributing to an enhanced performance.As a result,a LMB with the functionalized LLZTO IG electrolyte delivered more than 160 mA h g^(−1)with a very good capacity retention of 97.7%after 400 cycles in Li|IG|LFP cells.
文摘In the present work, carbon nano/microparticles obtained by controlled pyrolysis of peanut （PS） and hazelnut （HS） shells are presented. These materials were characterized by Raman spectroscopy and field emissionscanning electron microscopy （FE-SEM）. When added to cement paste, up to 1 wt%, these materials led to an increase of the cement matrix flexural strength and of toughness. Moreover, with respect to plain cement, the total increase in electromagnetic radiation shielding effect when adding 0.5 wt% of PS or HS in cement composites is much higher in comparison to the ones reported in the literature for CNTs used in the same content.
文摘From experime nts, the influe nee of the physical characteristics of different bin ary mixtures of solids on the spouting regime of a pyramidal square-based spouted bed reactor is assessed. The applied methodology permits a more precise evaluation of the effects of the tested variables (diameter, density, sphericity) on the response variables (minimum air flows at which spouting begins and at which to maintain spouting con ditions). The associated pressure drops along the bed of particles a nd the height of the formed fountai n are analysed in each case. During the initial stages of fluidisation, binary mixtures containing different density ratios show dead zones. Segregation becomes more evident at large-size and high-density ratios. The lack of sphericity was found to be the main reason leading to blocking, channelling, and start-up problems when system failures occur. Nevertheless, the extent of segregation in all cases decreases with increasing the spouting velocity. In addition, a computational fluid dynamic model based on the discrete element method, previously validated for a single solid bed, is proposed as a tool to predict and evaluate potential segregation phenomena in binary mixtures. This model reproduced with high accuracy the encountered segregation phenomena. Its use may help define the technical limts inherent in the pyramidal spouted bed reactor.
基金from the Italian Flagship Project NANOMAX(Progetto Bandiera MIUR PNR 2011–2013).
文摘In many optical applications,there is an increasing need for dynamically tunable optical elements that are able to shape the wavefront of light‘on demand’.In this work,an elastomeric easy-to-fabricate optical element whose transmission functions can be reversibly phase configured by visible light is demonstrated.The light responsivity of proper azopolymers incorporated within an elastomeric matrix is exploited to induce a light-controlled graded refractive index(GRIN)distribution within the bulk compound.The induced refractive index distribution is continuous and conformal to the intensity profile of the illumination at moderate power.A 100mW doubled-frequency Nd:YAG Gaussian beam focused to a 650μm waist is shown to induce a maximum relative refractive index change of~0.4%in the elastomeric matrix,with an approximately parabolic profile.The restoring characteristics of the elastomeric matrix enable full recovery of the initial homogeneous refractive index distribution within a few seconds when the incident laser is switched off.As an exemplary application,the configurable GRIN element is used in a microscope-based imaging system for light control of the effective focal length.
