In asymmetric rolling(ASR) the circumferential velocities of the working rolls are different. This yields a complex deformation mode with shear, compression and rigid body rotation components. The main microstructural...In asymmetric rolling(ASR) the circumferential velocities of the working rolls are different. This yields a complex deformation mode with shear, compression and rigid body rotation components. The main microstructural modification is on crystallographic texture, and, for aluminium alloys, this may improve the deformability after recrystallization. This work correlated the process variables, thickness reduction per pass(TRP) and velocity ratio between the upper and bottom rolls, with the texture development and the plastic properties after annealing. Finite element(FE) simulations were performed to quantify the influence of the strain components. Experimental data on texture, and plastic anisotropy were analyzed. In the sheet centre a crystallographic rotation of the compression components about the TD(transverse direction) axis was obtained, which yielded the development of {111}//ND(normal direction) texture components. On the surfaces the local variation of the velocity gradients caused an extra rotation component about ND. This yielded the increment of rotated cube components. After annealing the main texture components at the sheet centre were maintained and the texture intensity decreased. The planar anisotropy(△r) was reduced but the normal anisotropy and deep drawability obtained by the Erichsen test were similar for all conditions. The most favourable reduction of △r was obtained at a velocity ratio of 1.5 and TRP of 10%.展开更多
In this study,the relationship between spinodal decomposition and the formation of Ni-rich clusters and G-phase in the ferrite on hardening and pitting corrosion of two thermally aged duplex stainless steels(DSSs)at ...In this study,the relationship between spinodal decomposition and the formation of Ni-rich clusters and G-phase in the ferrite on hardening and pitting corrosion of two thermally aged duplex stainless steels(DSSs)at 475℃was investigated.Results indicate that,for 2205 DSS,pitting corrosion behavior is influenced by the presence and size of G-phase precipitates for longer aging times,but this contribution is masked by the advanced stage of spinodal decomposition in the ferritic structure.On the other hand,for 2101 DSS,the formation of Cr-richer nitrides impairs pitting corrosion resistance more than spinodal decomposition.展开更多
Nowadays,the production of consumer goods is based on the use of non-renewable raw materials,which in recent years has been performing as a problem for the environment.Considering the large number of available biofibe...Nowadays,the production of consumer goods is based on the use of non-renewable raw materials,which in recent years has been performing as a problem for the environment.Considering the large number of available biofibers in nature,their use in the development of polymeric composites has inevitably emerged,it is also necessary to take into account the countless discarded plastics that still have the potential to be reused.In this work,fibers were extracted from pineapple crown residues and utilized to compose sustainable composites using recycled polypropylene from cups discarded in the trash as a matrix.However,it is known that for good performance,it is necessary to achieve a good chemical interaction between the fiber and the matrix.In order to improve this interaction,alkaline mercerization treatment was carried out on the surface of the fibers removing some components incompatible with the polymer.In this work,the effect of the mercerization treatment on the properties of the fibers was studied,as well as their interaction with the matrix.The effect of fiber concentration on the mechanical and thermal properties of composites was also evaluated.Levels of 5 and 7 wt%were used for both natural and mercerized fibers.A decrease in the number of degradation stages was observed through thermogravimetry analyses(from four in natural fiber to two in mercerized fibers),showing that the mercerization performed on the fibers was effective.An increase in the degree of crystallinity of mercerized fibers was also observed through the results of X-ray diffraction.Both techniques indicate that amorphous compounds,such as hemicellulose and lignin,were partially removed.Through the tensile test,it could be noted that all composites presented higher values of de elastic modulus than recycled polypropylene without added load;however,there were no differences in the elastic modulus between the different types of fibers and load levels.Therefore,it is interesting to use fibers as reinforcing agents in polymers;however,the treatment did not increase the mechanical properties of the composites.In parallel,other factors,such as the dispersion of the components,must be taken into account to justify this result.展开更多
Re-deposition is a non-volatile etching by-product in reactive ion etching systems that is well known to cause dirt on etching work.In this study,we propose a novel etching method called the polymer-rich re-deposition...Re-deposition is a non-volatile etching by-product in reactive ion etching systems that is well known to cause dirt on etching work.In this study,we propose a novel etching method called the polymer-rich re-deposition technique,used particularly for improving the etched sidewall where the re-deposition is able to accumulate.This technique works by allowing the accumulated re-deposition on the etched sidewall to have a higher polymer species than the new compounds in the non-volatile etching by-product.The polymer-rich re-deposition is easy to remove along with the photo-resist mask residual at the photo-resist strip step using an isopropyl alcohol-based solution.The traditional,additional cleaning process step used to remove the re-deposition material is not required anymore,so this reduces the overall processing time.The technique is demonstrated on an Al_(2)O_(3)-TiC substrate by C4F8 plasma,and the EDX spectrum confirms that the polymer re-deposition has C and F atoms as the dominant atoms,suggesting that it is a C–F polymer re-deposition.展开更多
1.Introduction Optimizing the efficiency of platinum group metal(PGM)utilization in supported catalysts is critical due to the naturally low abundance,high costs,current demands,and expanding proposed applications of ...1.Introduction Optimizing the efficiency of platinum group metal(PGM)utilization in supported catalysts is critical due to the naturally low abundance,high costs,current demands,and expanding proposed applications of these metals.An emerging class of supported PGM catalysts that provides the potential for perfect metal utilization efficiency is single atom,or isolated site,PGMiso,catalysts where single PGM atoms are dispersed on a support[1–10].The potential for perfect metal utilization requires that all PGMiso sites exist in similar local bonding environments creating a constant reactivity across all sites.While many reports have demonstrated the utility of PGMiso catalysts,the limited“space”for reactant adsorption at such sites suggests that the range of potential applications may ultimately be dictated by an ability to introduce additional functionality around PGMiso species.In addition to the design of synthesis methods for producing these atomically precise supported catalysts,it is critical to develop site-specific characterization approaches that identify the existence of PGMiso species on supports,provide insight into their local bonding environment,and assess their reactivity.展开更多
A new modulated structure consisting of periodic （1120） stacking faults （SFs） in the α-Fe2O3 nanowires （NWs） formed by the thermal oxidation of Fe foils is reported, using a combination of high-resolution trans...A new modulated structure consisting of periodic （1120） stacking faults （SFs） in the α-Fe2O3 nanowires （NWs） formed by the thermal oxidation of Fe foils is reported, using a combination of high-resolution transmission electron microscopy （HRTEM） observations and HRTEM image simulations. The periodicity of the modulated structure is 1.53 nm, which is ten times （3500） interplanar spacing and can be described by a shift of every ten （3500） planes with 1/2 the interplanar spacing of the （1120） plane. An atomic model for the Fe203 structure is proposed to simulate the modulated structure. HRTEM simulation results confirm that the modulated structure in α-Fe2O3 NWs is caused by SFs.展开更多
Caffeine is an alkaloid present in a wide variety of plants. Currently the most consumed psychostimulant worldwide, its consumption is associated with several health benefits, including modulation of the innate and ad...Caffeine is an alkaloid present in a wide variety of plants. Currently the most consumed psychostimulant worldwide, its consumption is associated with several health benefits, including modulation of the innate and adaptive immune response, reduction of oxidative cellular stress, and decreased incidence of some cancers, including breast cancer. Breast cancer is the most common cause of cancer among women and the second leading cause of cancer death in women worldwide. The interaction between biomaterials and drugs has enabled a great advance in science for developing controlled drug delivery systems and has been used to treat numerous pathologies. This work aimed to evaluate the immunomodulatory effects of caffeine associated or not with polyethylene glycol adsorbed in microemulsion (MLP) on MCF-7 cells, phagocytic cells (MN), and coculture. For biological assays, ATCC (American Type Culture Collection, USA) cell lines of breast adenocarcinoma (MCF-7) and phagocytes (MN) obtained from voluntary donors were used. The cells (MN and MCF-7) and coculture were treated with caffeine and MLP and incubated for rheological characterization analyses: flow curve and viscosity, oxidative stress: superoxide anion assay (), and activity of the enzyme superoxide dismutase (Cu-Zn-SOD). Caffeine and MLP increased viscosity and blood and MCF-7 cells and affected the immunomodulation of oxidative stress metabolism of MN and MCF-7 cells treated with caffeine and associated caffeine to the MLP. These data suggest that caffeine is associated or not with MLP-induced immunomodulatory effects on MN phagocytes and MCF-7 cells, demonstrating the antitumor activity via oxidative stress and can be a complementary alternative for treating breast cancer.展开更多
Hierarchical plasmonic biomaterials constructed from small nanoparticles(NPs)that combine into larger micron-sized structures exhibit unique properties that can be harnessed for various applications.Using diffusion-li...Hierarchical plasmonic biomaterials constructed from small nanoparticles(NPs)that combine into larger micron-sized structures exhibit unique properties that can be harnessed for various applications.Using diffusion-limited aggregation(DLA)and defined peptide sequences,we developed fractal silver biomaterials with a Brownian tree structure.This method avoids complex redox chemistry and allows precise control of interparticle distance and material morphology through peptide design and concentration.Our systematic investigation revealed how peptide charge,length,and sequence impact biomaterial morphology,confirming that peptides act as bridging motifs between particles and induce coalescence.Characterization through spectroscopy and microscopy demonstrated that arginine-based peptides are optimal for fractal assembly based on both quantitative and qualitative measurements.Additionally,our study of diffusion behavior confirmed the effect of particle size,temperature,and medium viscosity on nanoparticle mobility.This work also provides insights into the facet distribution in silver NPs and their assembly mechanisms,offering potential advancements in the design of materials for medical,environmental,and electronic applications.展开更多
Coral-like structures of the Y_(3-x)Pr_(x)Fe_(5-y)Yb_(y)O_(12),(0.00 ≤ x ≤ 0.04, 0.00 ≤ y ≤ 0.02) compound were synthesized using the sol-gel method. Structural investigation certified the YIG cubic crystal struct...Coral-like structures of the Y_(3-x)Pr_(x)Fe_(5-y)Yb_(y)O_(12),(0.00 ≤ x ≤ 0.04, 0.00 ≤ y ≤ 0.02) compound were synthesized using the sol-gel method. Structural investigation certified the YIG cubic crystal structure formation, without any secondary phase. It is shown that, the relatively large ionic radius of the dopant cations results in an expansion of the lattice parameter, variations in the Iona-O-Iondangle, Iona-O,Iond-O and Ionc-O bond distances and decrease in the average crystallite size. Fourier transform infrared(FTIR) and Raman measurements are essential to testify the single-phase formation of YIG crystal structure and are observed changes in the stretching and vibrational modes, respectively. The morphological study, energy dispersive spectroscopy(EDS) spectra and textural properties show corallike structures, peaks associated with Pr^(3+) and Yb^(3+) atoms and the effect of dopants on surface area,diameter, and pore volume, respectively. The optical analysis from diffuse reflectance spectra witnessed an increase in the optical gap band, a decrease in Urbach energy and blue shift in the charge transfer,correlated with the expansion of the unit cell due to the dopant's insertion in the YIG structure. A typical ferrimagnetic behavior is exhibited by the Y_(3-x)Pr_(x)Fe_(5-y)Yb_(y)O_(12)compound. The saturation magnetization(M_(s)), cubic anisotropy constant(K_(1)) and coercive field(H_(c)) increase with the Pr^(3+)cations content, as consequence of their magnetic nature and distribution around of Fe^(3+)ions due to the coexistence with the Yb^(3+). Finally, for the first time, antibacterial tests by mean of the direct contact method were performed for YIG co-doped with Pr^(3+)and Yb^(3+)and it is shown that, relatively high dosages of Pr^(3+) cations favored the activity against S. aureus, therefore, a new biological property for YIG doped with rare earths is presented.展开更多
Anisotropic structures, nanoneedles, and nanospindles of rare earth hydroxychloride （RE（OH）2Cl） and oxychloride （REOCl） （rare earth=Eu and Tb） were synthesized. The rare earth hydroxychloride nanostructures we...Anisotropic structures, nanoneedles, and nanospindles of rare earth hydroxychloride （RE（OH）2Cl） and oxychloride （REOCl） （rare earth=Eu and Tb） were synthesized. The rare earth hydroxychloride nanostructures were formed via a thermally assisted hydrolysis of the rare-earth sesquioxide nanocrystals. The morphological evolution of the nanostructures was studied using high-resolution transmission electron microscopy and scanning electron microscopy, while the structural evolution was investigated using X-ray diffraction techniques. The thermal stability of the rare earth hydroxychlorides was investigated using thermogravimetric analysis. The rare earth oxychloride nanospindles were synthesized via a simple heat-treatment of rare earth hydroxychloride nanospindles.展开更多
We hereby propose a software solution to perform high quality electrical measurements for the characterization of WORM (write-once read many), a new generation memory device which is being intensively studied for non-...We hereby propose a software solution to perform high quality electrical measurements for the characterization of WORM (write-once read many), a new generation memory device which is being intensively studied for non-volatile data storage. The as-proposed software is completely based on .NET framework and sample C# code. The paper performed a relevant measurement based on this software. Working WORM devices, based on a polymeric matrix embedded with gold and copper sulfide nanoparticles, have been used for test measurements. The aim of this paper is to show the main steps to develop a fully working measurement software without using any expensive dedicated software.展开更多
Compositionally complex solid electrolyte(Li_(0.375)Sr_(0.4375))(Ta_(0.375)Nb_(0.375)Zr_(0.125)Hf_(0.125))O_(3)(LSTNZH)samples are synthesized using different sintering temperatures,durations,and cooling conditions(fu...Compositionally complex solid electrolyte(Li_(0.375)Sr_(0.4375))(Ta_(0.375)Nb_(0.375)Zr_(0.125)Hf_(0.125))O_(3)(LSTNZH)samples are synthesized using different sintering temperatures,durations,and cooling conditions(furnace cooling(FC)vs.air quenching(AQ)).The temperature-dependent grain growth has been examined to investigate the microstructural evolution and the origin of exaggerated(abnormal)grain growth.At moderate temperatures,the grain growth of LSTNZH follows a cubic root growth model with an Arrhenius temperature dependence.With increasing temperature,bimodal microstructures develop,and the Arrhenius temperature dependence breaks down.Notably,increasing the temperature induces increased Nb segregation at general grain boundaries(GBs),in contrast to classical GB segregation models but suggesting premelting-like GB disordering,which can explain the observed abnormal grain growth(AGG).In addition,the large grains become faceted with increasing temperature,which occurs concurrently with the temperature-induced transitions in GB segregation and grain growth,thereby further supporting the occurrence of a GB phase-like(complexion)transition.The impacts on the densification,ionic conductivity,and hardness are also examined.This work provides a new insight into the fundamental understanding of the grain growth mechanisms of the emergent class of medium-and high-entropy compositionally complex ceramics(CCCs),which is essential for tailoring microstructures and material properties.展开更多
Nanoscale quantum dot-antibody conjugates have been shown to self-assemble to form micron-scale aggregates in the presence of specific proteomic antigen.The self-assembly process exhibits sigmoidal kinetics,suggesting...Nanoscale quantum dot-antibody conjugates have been shown to self-assemble to form micron-scale aggregates in the presence of specific proteomic antigen.The self-assembly process exhibits sigmoidal kinetics,suggesting that nucleation limits aggregation.Self-assembly kinetics in this study is characterized by flow cytometric analysis of the aggregation reaction over time.A range of physiologically relevant concentrations of the protein angiopoietin-2,a candidate cancer biomarker,are incubated with quantum dots conjugated with a polyclonal mixture of anti-angiopoietin-2 antibodies.Antigen concentration modulates the slopes and inflection times of the sigmoidal kinetics curves.An understanding of self-assembly kinetics in this system may lead to improvements in sensitivity and specificity of this novel proteomic biomarker detection technique and improve the screening,diagnostics,and therapy response monitoring for cancers and other diseases.This approach to studying the kinetics of nanoparticle self-assembly may also provide a valuable tool for understanding the fundamental characteristics of nanoscale particle aggregation.展开更多
This study investigates the influence of waste characteristics,especially zeta potential,on the properties of cement pastes and solutions.The focus is to evaluate the impact of the zeta potential of cement particles a...This study investigates the influence of waste characteristics,especially zeta potential,on the properties of cement pastes and solutions.The focus is to evaluate the impact of the zeta potential of cement particles and waste materials on the sedimentation speed,rheology,and hardening time of stabilized cement pastes.Portland Cement II F 40,retarder additive,silica,and fly ash were used in the research.The pastes were prepared,and during the stabilization period,their rheological properties and pH were evaluated.The zeta potential and sedimentation speed of the cement and waste particles were measured at the pH that the pastes presented during the entire stabilization period.After the stabilization period,the pastes were subjected to the hardening time test.The zeta potential analyses revealed diverse values for the different powder types,with the cement particles exhibiting a zeta potential of−3.0 mV,the silica particles exhibiting−10.5 mV,and the fly ash particles exhibiting−20.3 mV.The influence of the high zeta potential modulus was observed on the sedimentation speed,with the solution containing fly ash exhibiting a speed of 40.01μm/s,whereas the solution containing only cement exhibited a speed of 99.38μm/s.In the pastes,the results indicate that the presence of fly ash particles with a significantly negative zeta potential led to a 16%reduction in hardening time compared to particles with a lower modulus of zeta potential.Rheometry tests showed that the inclusion of fly ash particles prevented the formation of agglomerates.Although the zeta potential influenced agglomerate formation and hardening time,it was found to have no effect on yield stress or viscosity.展开更多
Machine learning is an emerging tool in the field of materials chemistry for uncovering a principle from large datasets.Here,we focus on the spherical precipitation behavior of polymers and computationally extract a h...Machine learning is an emerging tool in the field of materials chemistry for uncovering a principle from large datasets.Here,we focus on the spherical precipitation behavior of polymers and computationally extract a hidden trend that is orthogonal to the availability bias in the chemical space.For constructing a dataset,four polymers were precipitated from 416 solvent/nonsolvent combinations,and the morphology of the resulting precipitates were collected.The dataset was subjected to computational investigations consisting of principal component analysis and machine learning based on random forest model and support vector machine.Thereby,we eliminated the effect of the availability bias and found a linear combination of Hansen parameters to be the most suitable variable for predicting precipitation behavior.The predicted appropriate solvents are those with low hydrogen bonding capability,low polarity,and small molecular volume.Furthermore,we found that the capability for spherical precipitation is orthogonal to the availability bias and forms an extraordinary axis in Hansen space,which is the origin of the conventional difficulty in identifying the trend.The extraordinary axis points toward a void region,indicating the potential value of synthesizing novel solvents located therein.展开更多
基金supported by Sao Paulo State Research Foundation (FAPESP 2016/10997-0)by CAPES–Brazil
文摘In asymmetric rolling(ASR) the circumferential velocities of the working rolls are different. This yields a complex deformation mode with shear, compression and rigid body rotation components. The main microstructural modification is on crystallographic texture, and, for aluminium alloys, this may improve the deformability after recrystallization. This work correlated the process variables, thickness reduction per pass(TRP) and velocity ratio between the upper and bottom rolls, with the texture development and the plastic properties after annealing. Finite element(FE) simulations were performed to quantify the influence of the strain components. Experimental data on texture, and plastic anisotropy were analyzed. In the sheet centre a crystallographic rotation of the compression components about the TD(transverse direction) axis was obtained, which yielded the development of {111}//ND(normal direction) texture components. On the surfaces the local variation of the velocity gradients caused an extra rotation component about ND. This yielded the increment of rotated cube components. After annealing the main texture components at the sheet centre were maintained and the texture intensity decreased. The planar anisotropy(△r) was reduced but the normal anisotropy and deep drawability obtained by the Erichsen test were similar for all conditions. The most favourable reduction of △r was obtained at a velocity ratio of 1.5 and TRP of 10%.
基金PPGCEM/UFSCar(Materials Science and Engineering Postgraduate Program at the Federal University of São Carlos)CNPq(National Council for Scientific and Technological Development,Brazil-grant no.311163/2017-3 and 312614/2020-9)FAPESP(São Paulo Research Foundation,Brazil–grant no.2020/03205-6)
文摘In this study,the relationship between spinodal decomposition and the formation of Ni-rich clusters and G-phase in the ferrite on hardening and pitting corrosion of two thermally aged duplex stainless steels(DSSs)at 475℃was investigated.Results indicate that,for 2205 DSS,pitting corrosion behavior is influenced by the presence and size of G-phase precipitates for longer aging times,but this contribution is masked by the advanced stage of spinodal decomposition in the ferritic structure.On the other hand,for 2101 DSS,the formation of Cr-richer nitrides impairs pitting corrosion resistance more than spinodal decomposition.
基金The authors would like to thank CAPES(Finance Code 001 and Process PNPD20131474-33001014004P9)and CNPq for financial support.
文摘Nowadays,the production of consumer goods is based on the use of non-renewable raw materials,which in recent years has been performing as a problem for the environment.Considering the large number of available biofibers in nature,their use in the development of polymeric composites has inevitably emerged,it is also necessary to take into account the countless discarded plastics that still have the potential to be reused.In this work,fibers were extracted from pineapple crown residues and utilized to compose sustainable composites using recycled polypropylene from cups discarded in the trash as a matrix.However,it is known that for good performance,it is necessary to achieve a good chemical interaction between the fiber and the matrix.In order to improve this interaction,alkaline mercerization treatment was carried out on the surface of the fibers removing some components incompatible with the polymer.In this work,the effect of the mercerization treatment on the properties of the fibers was studied,as well as their interaction with the matrix.The effect of fiber concentration on the mechanical and thermal properties of composites was also evaluated.Levels of 5 and 7 wt%were used for both natural and mercerized fibers.A decrease in the number of degradation stages was observed through thermogravimetry analyses(from four in natural fiber to two in mercerized fibers),showing that the mercerization performed on the fibers was effective.An increase in the degree of crystallinity of mercerized fibers was also observed through the results of X-ray diffraction.Both techniques indicate that amorphous compounds,such as hemicellulose and lignin,were partially removed.Through the tensile test,it could be noted that all composites presented higher values of de elastic modulus than recycled polypropylene without added load;however,there were no differences in the elastic modulus between the different types of fibers and load levels.Therefore,it is interesting to use fibers as reinforcing agents in polymers;however,the treatment did not increase the mechanical properties of the composites.In parallel,other factors,such as the dispersion of the components,must be taken into account to justify this result.
基金Supported by the Industry/University Cooperative Research Center in Data Storage Technology and Applications,King Mongkut’s Institute of Technology Ladkrabang and the National Electronics and Computer Technology Center,the National Science and Technology Development Agencythe Commission of Higher Education under the National Research University(NRU)Project.
文摘Re-deposition is a non-volatile etching by-product in reactive ion etching systems that is well known to cause dirt on etching work.In this study,we propose a novel etching method called the polymer-rich re-deposition technique,used particularly for improving the etched sidewall where the re-deposition is able to accumulate.This technique works by allowing the accumulated re-deposition on the etched sidewall to have a higher polymer species than the new compounds in the non-volatile etching by-product.The polymer-rich re-deposition is easy to remove along with the photo-resist mask residual at the photo-resist strip step using an isopropyl alcohol-based solution.The traditional,additional cleaning process step used to remove the re-deposition material is not required anymore,so this reduces the overall processing time.The technique is demonstrated on an Al_(2)O_(3)-TiC substrate by C4F8 plasma,and the EDX spectrum confirms that the polymer re-deposition has C and F atoms as the dominant atoms,suggesting that it is a C–F polymer re-deposition.
文摘1.Introduction Optimizing the efficiency of platinum group metal(PGM)utilization in supported catalysts is critical due to the naturally low abundance,high costs,current demands,and expanding proposed applications of these metals.An emerging class of supported PGM catalysts that provides the potential for perfect metal utilization efficiency is single atom,or isolated site,PGMiso,catalysts where single PGM atoms are dispersed on a support[1–10].The potential for perfect metal utilization requires that all PGMiso sites exist in similar local bonding environments creating a constant reactivity across all sites.While many reports have demonstrated the utility of PGMiso catalysts,the limited“space”for reactant adsorption at such sites suggests that the range of potential applications may ultimately be dictated by an ability to introduce additional functionality around PGMiso species.In addition to the design of synthesis methods for producing these atomically precise supported catalysts,it is critical to develop site-specific characterization approaches that identify the existence of PGMiso species on supports,provide insight into their local bonding environment,and assess their reactivity.
基金Project supported by the National Key Basic Research Development Program of China (Grant No.2012CB722705)the Natural Science Foundation for Outstanding Young Scientists in Shandong Province,China (Grant No.JQ201002)+2 种基金the Program for Foreign Cultural and Educational Experts (Grant No.20123702083)the Program for Higher Education Science and Technology in Shandong Province (Grant No.J12LA17)Wang Yi-Qian would like to thank the financial support from Taishan Outstanding Overseas Scholar Program of Shandong Province,China
文摘A new modulated structure consisting of periodic （1120） stacking faults （SFs） in the α-Fe2O3 nanowires （NWs） formed by the thermal oxidation of Fe foils is reported, using a combination of high-resolution transmission electron microscopy （HRTEM） observations and HRTEM image simulations. The periodicity of the modulated structure is 1.53 nm, which is ten times （3500） interplanar spacing and can be described by a shift of every ten （3500） planes with 1/2 the interplanar spacing of the （1120） plane. An atomic model for the Fe203 structure is proposed to simulate the modulated structure. HRTEM simulation results confirm that the modulated structure in α-Fe2O3 NWs is caused by SFs.
文摘Caffeine is an alkaloid present in a wide variety of plants. Currently the most consumed psychostimulant worldwide, its consumption is associated with several health benefits, including modulation of the innate and adaptive immune response, reduction of oxidative cellular stress, and decreased incidence of some cancers, including breast cancer. Breast cancer is the most common cause of cancer among women and the second leading cause of cancer death in women worldwide. The interaction between biomaterials and drugs has enabled a great advance in science for developing controlled drug delivery systems and has been used to treat numerous pathologies. This work aimed to evaluate the immunomodulatory effects of caffeine associated or not with polyethylene glycol adsorbed in microemulsion (MLP) on MCF-7 cells, phagocytic cells (MN), and coculture. For biological assays, ATCC (American Type Culture Collection, USA) cell lines of breast adenocarcinoma (MCF-7) and phagocytes (MN) obtained from voluntary donors were used. The cells (MN and MCF-7) and coculture were treated with caffeine and MLP and incubated for rheological characterization analyses: flow curve and viscosity, oxidative stress: superoxide anion assay (), and activity of the enzyme superoxide dismutase (Cu-Zn-SOD). Caffeine and MLP increased viscosity and blood and MCF-7 cells and affected the immunomodulation of oxidative stress metabolism of MN and MCF-7 cells treated with caffeine and associated caffeine to the MLP. These data suggest that caffeine is associated or not with MLP-induced immunomodulatory effects on MN phagocytes and MCF-7 cells, demonstrating the antitumor activity via oxidative stress and can be a complementary alternative for treating breast cancer.
基金University of California,San Diego-Cellular and Molecular Medicine Electron Microscopy Core,Grant/Award Number:SCR_022039National Institutes of Health,Grant/Award Numbers:S10 OD023527,R21 DE029917,R01 DE031307,S10OD023555-A1National Science Foundation,Grant/Award Numbers:DMR-2242375,DMR-2011924,ECCS-2025752。
文摘Hierarchical plasmonic biomaterials constructed from small nanoparticles(NPs)that combine into larger micron-sized structures exhibit unique properties that can be harnessed for various applications.Using diffusion-limited aggregation(DLA)and defined peptide sequences,we developed fractal silver biomaterials with a Brownian tree structure.This method avoids complex redox chemistry and allows precise control of interparticle distance and material morphology through peptide design and concentration.Our systematic investigation revealed how peptide charge,length,and sequence impact biomaterial morphology,confirming that peptides act as bridging motifs between particles and induce coalescence.Characterization through spectroscopy and microscopy demonstrated that arginine-based peptides are optimal for fractal assembly based on both quantitative and qualitative measurements.Additionally,our study of diffusion behavior confirmed the effect of particle size,temperature,and medium viscosity on nanoparticle mobility.This work also provides insights into the facet distribution in silver NPs and their assembly mechanisms,offering potential advancements in the design of materials for medical,environmental,and electronic applications.
基金The authors are grateful to the Brazilian Agencies:Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior(CAPES),Conselho Nacional de Desenvolvimento Cientifico e Tecnologico(CNPq),(CNPq N 4/2021-Bolsa de Produtividade em Pesquisa-PQ 307659/2021-6),(Chamada CNPq/MCTI/FNDCT N°18/2021-Faixa A,407796/2021-5)Financiadora de Estudos e Projetos(FINEP)and Fundacao de Amparo a Ciencia e Tecnologia de Pernambuco(FACEPE)(APQ-0635-3.03/21-Jovens Pesquisadores).
文摘Coral-like structures of the Y_(3-x)Pr_(x)Fe_(5-y)Yb_(y)O_(12),(0.00 ≤ x ≤ 0.04, 0.00 ≤ y ≤ 0.02) compound were synthesized using the sol-gel method. Structural investigation certified the YIG cubic crystal structure formation, without any secondary phase. It is shown that, the relatively large ionic radius of the dopant cations results in an expansion of the lattice parameter, variations in the Iona-O-Iondangle, Iona-O,Iond-O and Ionc-O bond distances and decrease in the average crystallite size. Fourier transform infrared(FTIR) and Raman measurements are essential to testify the single-phase formation of YIG crystal structure and are observed changes in the stretching and vibrational modes, respectively. The morphological study, energy dispersive spectroscopy(EDS) spectra and textural properties show corallike structures, peaks associated with Pr^(3+) and Yb^(3+) atoms and the effect of dopants on surface area,diameter, and pore volume, respectively. The optical analysis from diffuse reflectance spectra witnessed an increase in the optical gap band, a decrease in Urbach energy and blue shift in the charge transfer,correlated with the expansion of the unit cell due to the dopant's insertion in the YIG structure. A typical ferrimagnetic behavior is exhibited by the Y_(3-x)Pr_(x)Fe_(5-y)Yb_(y)O_(12)compound. The saturation magnetization(M_(s)), cubic anisotropy constant(K_(1)) and coercive field(H_(c)) increase with the Pr^(3+)cations content, as consequence of their magnetic nature and distribution around of Fe^(3+)ions due to the coexistence with the Yb^(3+). Finally, for the first time, antibacterial tests by mean of the direct contact method were performed for YIG co-doped with Pr^(3+)and Yb^(3+)and it is shown that, relatively high dosages of Pr^(3+) cations favored the activity against S. aureus, therefore, a new biological property for YIG doped with rare earths is presented.
文摘Anisotropic structures, nanoneedles, and nanospindles of rare earth hydroxychloride （RE（OH）2Cl） and oxychloride （REOCl） （rare earth=Eu and Tb） were synthesized. The rare earth hydroxychloride nanostructures were formed via a thermally assisted hydrolysis of the rare-earth sesquioxide nanocrystals. The morphological evolution of the nanostructures was studied using high-resolution transmission electron microscopy and scanning electron microscopy, while the structural evolution was investigated using X-ray diffraction techniques. The thermal stability of the rare earth hydroxychlorides was investigated using thermogravimetric analysis. The rare earth oxychloride nanospindles were synthesized via a simple heat-treatment of rare earth hydroxychloride nanospindles.
文摘We hereby propose a software solution to perform high quality electrical measurements for the characterization of WORM (write-once read many), a new generation memory device which is being intensively studied for non-volatile data storage. The as-proposed software is completely based on .NET framework and sample C# code. The paper performed a relevant measurement based on this software. Working WORM devices, based on a polymeric matrix embedded with gold and copper sulfide nanoparticles, have been used for test measurements. The aim of this paper is to show the main steps to develop a fully working measurement software without using any expensive dedicated software.
基金supported by the National Science Foundation(NSF)Materials Research Science and Engineering Center(MRSEC)program through the UC Irvine Center for Complex and Active Materials(CCAM)under No.DMR2011967This work used shared facilities at the Irvine Materials Research Institute(also supported in part by the NSF DMR2011967)+3 种基金the San Diego Nanotechnology Infrastructure(SDNI)of UCSD,a member of the National Nanotechnology Coordinated Infrastructure(NSF ECCS-2025752)the NSF Center for Chemistry at the Space–Time Limit(CHE-0802913)the UC San Diego MRSEC shared instrumentation(NSF Grant DMR2011924)the UC San Diego Nanoengineering Materials Research Center(NE-MRC).
文摘Compositionally complex solid electrolyte(Li_(0.375)Sr_(0.4375))(Ta_(0.375)Nb_(0.375)Zr_(0.125)Hf_(0.125))O_(3)(LSTNZH)samples are synthesized using different sintering temperatures,durations,and cooling conditions(furnace cooling(FC)vs.air quenching(AQ)).The temperature-dependent grain growth has been examined to investigate the microstructural evolution and the origin of exaggerated(abnormal)grain growth.At moderate temperatures,the grain growth of LSTNZH follows a cubic root growth model with an Arrhenius temperature dependence.With increasing temperature,bimodal microstructures develop,and the Arrhenius temperature dependence breaks down.Notably,increasing the temperature induces increased Nb segregation at general grain boundaries(GBs),in contrast to classical GB segregation models but suggesting premelting-like GB disordering,which can explain the observed abnormal grain growth(AGG).In addition,the large grains become faceted with increasing temperature,which occurs concurrently with the temperature-induced transitions in GB segregation and grain growth,thereby further supporting the occurrence of a GB phase-like(complexion)transition.The impacts on the densification,ionic conductivity,and hardness are also examined.This work provides a new insight into the fundamental understanding of the grain growth mechanisms of the emergent class of medium-and high-entropy compositionally complex ceramics(CCCs),which is essential for tailoring microstructures and material properties.
文摘Nanoscale quantum dot-antibody conjugates have been shown to self-assemble to form micron-scale aggregates in the presence of specific proteomic antigen.The self-assembly process exhibits sigmoidal kinetics,suggesting that nucleation limits aggregation.Self-assembly kinetics in this study is characterized by flow cytometric analysis of the aggregation reaction over time.A range of physiologically relevant concentrations of the protein angiopoietin-2,a candidate cancer biomarker,are incubated with quantum dots conjugated with a polyclonal mixture of anti-angiopoietin-2 antibodies.Antigen concentration modulates the slopes and inflection times of the sigmoidal kinetics curves.An understanding of self-assembly kinetics in this system may lead to improvements in sensitivity and specificity of this novel proteomic biomarker detection technique and improve the screening,diagnostics,and therapy response monitoring for cancers and other diseases.This approach to studying the kinetics of nanoparticle self-assembly may also provide a valuable tool for understanding the fundamental characteristics of nanoscale particle aggregation.
文摘This study investigates the influence of waste characteristics,especially zeta potential,on the properties of cement pastes and solutions.The focus is to evaluate the impact of the zeta potential of cement particles and waste materials on the sedimentation speed,rheology,and hardening time of stabilized cement pastes.Portland Cement II F 40,retarder additive,silica,and fly ash were used in the research.The pastes were prepared,and during the stabilization period,their rheological properties and pH were evaluated.The zeta potential and sedimentation speed of the cement and waste particles were measured at the pH that the pastes presented during the entire stabilization period.After the stabilization period,the pastes were subjected to the hardening time test.The zeta potential analyses revealed diverse values for the different powder types,with the cement particles exhibiting a zeta potential of−3.0 mV,the silica particles exhibiting−10.5 mV,and the fly ash particles exhibiting−20.3 mV.The influence of the high zeta potential modulus was observed on the sedimentation speed,with the solution containing fly ash exhibiting a speed of 40.01μm/s,whereas the solution containing only cement exhibited a speed of 99.38μm/s.In the pastes,the results indicate that the presence of fly ash particles with a significantly negative zeta potential led to a 16%reduction in hardening time compared to particles with a lower modulus of zeta potential.Rheometry tests showed that the inclusion of fly ash particles prevented the formation of agglomerates.Although the zeta potential influenced agglomerate formation and hardening time,it was found to have no effect on yield stress or viscosity.
基金CREST,Grant/Award Number:JPMJCR20T4ACT-X,Grant/Award Number:JPMJAX201JGrant-in-Aid for Young Scientist,Grant/Award Number:JP22K14656。
文摘Machine learning is an emerging tool in the field of materials chemistry for uncovering a principle from large datasets.Here,we focus on the spherical precipitation behavior of polymers and computationally extract a hidden trend that is orthogonal to the availability bias in the chemical space.For constructing a dataset,four polymers were precipitated from 416 solvent/nonsolvent combinations,and the morphology of the resulting precipitates were collected.The dataset was subjected to computational investigations consisting of principal component analysis and machine learning based on random forest model and support vector machine.Thereby,we eliminated the effect of the availability bias and found a linear combination of Hansen parameters to be the most suitable variable for predicting precipitation behavior.The predicted appropriate solvents are those with low hydrogen bonding capability,low polarity,and small molecular volume.Furthermore,we found that the capability for spherical precipitation is orthogonal to the availability bias and forms an extraordinary axis in Hansen space,which is the origin of the conventional difficulty in identifying the trend.The extraordinary axis points toward a void region,indicating the potential value of synthesizing novel solvents located therein.
