By and large the research communities today are not fully aware of the remarkable universality in the dynamic properties of many-body relaxation/diffusion processes manifested in experiments and simulations on condens...By and large the research communities today are not fully aware of the remarkable universality in the dynamic properties of many-body relaxation/diffusion processes manifested in experiments and simulations on condensed matter with diverse chemical compositions and physical structures. I shall demonstrate the universality first from the dynamic processes in glass-forming systems. This is reinforced by strikingly similar properties of different processes in contrasting interacting systems all having nothing to do with glass transition. The examples given here include glass-forming systems of diverse chemical compositions and physical structures, conductivity relaxation of ionic conductors（liquid, glassy, and crystalline）,translation and orientation ordered phase of rigid molecule, and polymer chain dynamics. Universality is also found in the change of dynamics when dimension is reduced to nanometer size in widely different systems. The remarkable universality indicates that many-body relaxation/diffusion is governed by fundamental physics to be unveiled. One candidate is classical chaos on which the coupling model is based, Universal properties predicted by this model are in accord with diverse experiments and simulations.展开更多
The present study investigates the effect of a silver (Ag)-containing nanocomposite coating on Staphylococcus epidermidis adhesion and icaA gene expression. Bacterial interactions with organic coatings with and withou...The present study investigates the effect of a silver (Ag)-containing nanocomposite coating on Staphylococcus epidermidis adhesion and icaA gene expression. Bacterial interactions with organic coatings with and without Ag nanoclusters were assessed through a combination of both conventional phenotypic analysis, using microscopy, and genotypic analysis, using the relative reverse transcription Real-Time Polymerase Chain Reaction (RT-PCR). The results suggest that the incorporation of Ag in organic coatings can significantly decrease bacterial adhesion and viability with time, in comparison to the organic coating alone. The initial Ag release though at concentrations lower than the bactericidal, significantly increased icaA gene expression for the bacteria interacting with the Ag containing coating two hours post adhesion, especially under the higher shear rate. Stress-inducing conditions such as sub-bactericidal concentrations of Ag and high shear rate can therefore increase icaA expression, indicating that analysis of gene expression can not only refine our knowledge of bacterial-material interactions, but also yield novel biomarkers for potential use in assessing biomaterials antimicrobial performance.展开更多
In recent years the development of chitosan (CH) based materials as useful adsorbent polymeric matrices is an expanding field in the area of adsorption science. Even though CH has been successfully used for dye remova...In recent years the development of chitosan (CH) based materials as useful adsorbent polymeric matrices is an expanding field in the area of adsorption science. Even though CH has been successfully used for dye removal from aqueous solutions due to its low cost, no considerations have been made about, for example, the effect of changing the pH of chitosan hydrogelor about the dehydrating effect of Ethanol (EtOH) treatment of chitosan film on the dyes removal from water. Consequently in our laboratory we carried out a study focusing the attention, mainly, on the potential use of CH films under different conditions, such as reducing the intrinsic pH, increasing the hydrophobic character by means of ethanol treatment and neutralization of CH films to improve their absorption power. Textile anionic dyes named Direct Red 83:1, Direct Yellow 86 and Direct Blue 78 have been studied with the aim of reducing the contact time of CH film in waste water improving the bleaching efficiency. Neutralized acid CH film and longtime dehydrated one result to be the better films in dye removal from water. Also the reduction of the CH solution acidity during the film preparation determines the decreasing of the contact time improving the results. The effect of initial dye concentration has been examined and the amount of dye adsorption in function of time t, qt (mg/cm2), for each analyzed film has been evaluated comparing the long term effect with the decoloration rate. A linear form of pseudo-first-order Lagergren model has been used and described. The best condition for removing all examined dyes from various dye solutions appears to be the dehydration of a novel projected CH film obtained by means of the film immersion in EtOH for 4 days. Also CH films prepared by well-known literature procedure and neutralized with NaOH treatment appear having an excellent behavior, however the film treatment requires a large quantity of water and time.展开更多
Beyond traditional rooftop and building-integrated photovoltaics(BIPV),photovoltaic(PV)devices find applications in agrivoltaics,space,and indoor settings.However,the underwater(UW)environment remains largely unexplor...Beyond traditional rooftop and building-integrated photovoltaics(BIPV),photovoltaic(PV)devices find applications in agrivoltaics,space,and indoor settings.However,the underwater(UW)environment remains largely unexplored.Below 50 m,the solar spectrum shifts dramatically,with only blue-green light(400–600 nm)available.Perovskite solar cells(PSCs),known for their high-power conversion efficiencies(PCEs)and tunable bandgaps,offer potential for this environment.Initially,simulations compared the intensity of the solar radiation based on three models,each based on a different water body,down to a depth of 10 m.展开更多
We produced a microstructured,electroconductive and nano-functionalized drug eluting cardiac patch(MEN-DEP)designed to attract endogenous precursor cells,favor their differentiation and counteract adverse ven-tricular...We produced a microstructured,electroconductive and nano-functionalized drug eluting cardiac patch(MEN-DEP)designed to attract endogenous precursor cells,favor their differentiation and counteract adverse ven-tricular remodeling in situ.MENDEP showed mechanical anisotropy and biaxial strength comparable to porcine myocardium,reduced impedance,controlled biodegradability,molecular recognition ability and controlled drug release activity.In vitro,cytocompatibility and cardioinductivity were demonstrated.Migration tests showed the chemoattractive capacity of the patches and conductivity assays showed unaltered cell-cell interactions and cell beating synchronicity.MENDEP was then epicardially implanted in a rat model of ischemia/reperfusion(I/R).Histological,immunofluorescence and biomarker analysis indicated that implantation did not cause damage to the healthy myocardium.After I/R,MENDEP recruited precursor cells into the damaged myocardium and triggered their differentiation towards the vascular lineage.Under the patch,the myocardial tissue appeared well preserved and cardiac gap junctions were correctly distributed at the level of the intercalated discs.The fibrotic area measured in the I/R group was partially reduced in the patch group.展开更多
We report on the unconventional optical properties exhibited by a two-dimensional array of thin Si nanowires arranged in a random fractal geometry and fabricated using an inexpensive,fast and maskless process compatib...We report on the unconventional optical properties exhibited by a two-dimensional array of thin Si nanowires arranged in a random fractal geometry and fabricated using an inexpensive,fast and maskless process compatible with Si technology.The structure allows for a high light-trapping efficiency across the entire visible range,attaining total reflectance values as low as 0.1%when the wavelength in the medium matches the length scale of maximum heterogeneity in the system.We show that the random fractal structure of our nanowire array is responsible for a strong in-plane multiple scattering,which is related to the material refractive index fluctuations and leads to a greatly enhanced Raman scattering and a bright photoluminescence.These strong emissions are correlated on all length scales according to the refractive index fluctuations.The relevance and the perspectives of the reported results are discussed as promising for Si-based photovoltaic and photonic applications.展开更多
The degradation process of cellulose-made materials was investigated by means of nuclear magnetic resonance （NMR） spectroscopy, with particular emphasis on the role of water and on the hydration mechanism of cellulo...The degradation process of cellulose-made materials was investigated by means of nuclear magnetic resonance （NMR） spectroscopy, with particular emphasis on the role of water and on the hydration mechanism of cellulose fibrils. To accomplish this, the structure and dynamics of water within ancient and modern samples with different aging histories were investigated. The results mainly indicated that hydrolytic and oxidative reactions provoked the formation of acidic by-products. Furthermore, degradation processes were enhanced by higher amounts of water giving a progressive consumption of the amorphous regions of the cellulose. We propose NMR experiments as a benchmark for character- ization of the degradation state of paper, as well as for investigating the effectiveness of restoration treatments.展开更多
Living photovoltaics are microbial electrochemical devices that use whole cell–electrode interactions to convert solar energy to electricity.The bottleneck in these technologies is the limited electron transfer betwe...Living photovoltaics are microbial electrochemical devices that use whole cell–electrode interactions to convert solar energy to electricity.The bottleneck in these technologies is the limited electron transfer between the microbe and the electrode surface.This study focuses on enhancing this transfer by engineering a polydopamine(PDA)coating on the outer membrane of the photosynthetic microbe Synechocystis sp.PCC6803.This coating provides a conductive nanoparticle shell to increase electrode adhesion and improve microbial charge extraction.A combination of scanning electron microscopy(SEM),transmission electron microscopy(TEM),UV–Vis absorption,and Raman spectroscopy measurements were used to characterize the nanoparticle shell under various synthesis conditions.The cell viability and activity were further assessed through oxygen evolution,growth curve,and confocal fluorescence microscopy measurements.The results show sustained cell growth and detectable PDA surface coverage under slightly alkaline conditions(pH 7.5)and at low initial dopamine(DA)concentrations(1 mM).The exoelectrogenicity of the cells prepared under these conditions was also characterized through cyclic voltammetry(CV)and chronoamperometry(CA).The measurements show a three-fold enhancement in the photocurrent at an applied bias of 0.3 V(vs.Ag/AgCl[3 M KCl])compared to non-coated cells.This study thus lays the framework for engineering the next generation of living photovoltaics with improved performances using biosynthetic electrodes.展开更多
The self-assembling properties, stability, and dynamics of hybrid nanocarriers （gold nanoparticles （AuNPs） functionalized with cysteine-based peptides） in solution are studied through a series of classical molecul...The self-assembling properties, stability, and dynamics of hybrid nanocarriers （gold nanoparticles （AuNPs） functionalized with cysteine-based peptides） in solution are studied through a series of classical molecular dynamics simulations based on a recently parametrized reactive force field. The results reveal, at the atomic level, all the details regarding the peptide adsorption mechanisms, nanoparticle stabilization, aggregation, and sintering. The data confirm and explain the experimental findings and disclose aspects that cannot be scrutinized by experiments. The biomolecules are both chemisorbed and physisorbed; self-interactions of the adsorbates and formation of stable networks of inter- connected molecules on the AuNP surfaces limit substrate reconstructions, protect the AuNPs from the action of the solvent, and prevent direct interactions of the gold surfaces. The possibility of agglomeration of the functionalized nanoparticles, compared with the sintering of the bare supports in a water solution, is demonstrated through relatively long simulations and fast steered dynamics. The analysis of the trajectories reveals that the AuNPs were well stabilized by the peptides. This prevented particle sintering and kept the particles far apart; however, part of their chains could form interconnections （crosslinks） between neighboring gold vehicles. The excellent agreement of these results with the literature confirm the reliability of the method and its potential application to the modeling of more complex materials relevant to the biomedical sector.展开更多
In this paper we propose a computational framework for the investigation of the correlated motion between positive and negative ions exposed to the attraction of a bubble surface that mimics the(oscillating)cell membr...In this paper we propose a computational framework for the investigation of the correlated motion between positive and negative ions exposed to the attraction of a bubble surface that mimics the(oscillating)cell membrane.Specifically we aim to investigate the role of surface traps with substances freely diffusing around the cell.The physical system we want to model is an anchored gas drop submitted to a diffusive flowof charged surfactants(ions).When the diffusing surfactantsmeet the surface of the bubble,they are reversibly adsorbed and their local concentration is accurately measured.The correlated diffusion of surfactants is described by a Poisson-Nernst-Planck(PNP)system,in which the drift term is given by the gradient of a potential which includes both the effect of the bubble and the Coulomb interaction between the carriers.The latter term is obtained from the solution of a self-consistent Poisson equation.For very short Debye lengths one can adopt the so called Quasi-Neutral limit which drastically simplifies the system,thus allowing for much faster numerical simulations.The paper has four main objectives.The first one is to present a PNP model that describes ion charges in presence of a trap.The second one is to provide benchmark tests for the validation of simplified multiscale models under current development[1].The third one is to explore the relevance of the term describing the interaction among the apolar tails of the anions.The last one is to quantitatively explore the validity of the Quasi-Neutral limit by comparison with detailed numerical simulation for smaller and smaller Debye lengths.In order to reach these goals,we propose a simple and efficient Alternate Direction Implicit method for the numerical solution of the non-linear PNP system,which guarantees second order accuracy both in space and time,without requiring solution of nonlinear equation at each time step.New semi-implicit scheme for a simplified PNP system near quasi neutrality is also proposed.展开更多
The spatial domain of Molecular Dynamics simulations is usually a regular box that can be easily divided in subdomains for parallel processing.Recent efforts aimed at simulating complex biological systems,like the blo...The spatial domain of Molecular Dynamics simulations is usually a regular box that can be easily divided in subdomains for parallel processing.Recent efforts aimed at simulating complex biological systems,like the blood flow inside arteries,require the execution of Parallel Molecular Dynamics(PMD)in vessels that have,by nature,an irregular shape.In those cases,the geometry of the domain becomes an additional input parameter that directly influences the outcome of the simulation.In this paper we discuss the problems due to the parallelization of MD in complex geometries and show an efficient and general method to perform MD in irregular domains.展开更多
Water properties are dominated by the hydrogen bond interaction that gives rise in the stable liquid phase to the formation of a dynamical network.The latter drives the water thermodynamics and is at the origin of its...Water properties are dominated by the hydrogen bond interaction that gives rise in the stable liquid phase to the formation of a dynamical network.The latter drives the water thermodynamics and is at the origin of its well known anomalies.The HB structural geometry and its changes remain uncertain and still are challenging research subjects.A key question is the role and effects of the HB tetrahedral structure on the local arrangement of neighboring molecules in water.Here the hydrogen dynamics in bulk water is studied through the combined use of Neutron Compton Scattering and NMR techniques.Results are discussed in the framework of previous studies performed in a wide temperature range,in the liquid,solid,and amorphous states.For the first time this combined studies provide an experimental evidence of the onset of the water tetrahedral network at T^315 K,originally proposed in previous studies of transport coefficients and thermodynamical data;below this temperature the local order in water changes and the lifetime of local hydrogen bond network becomes long enough to gradually develop the characteristic tetrahedral network of water.展开更多
We study the dynanfics of the first hydration shell of lysozyme to determine the role of hydra- tion water that accompanies lysozyme thermal denaturation. We use nuclear magnetic resonance spectroscopy to investigate ...We study the dynanfics of the first hydration shell of lysozyme to determine the role of hydra- tion water that accompanies lysozyme thermal denaturation. We use nuclear magnetic resonance spectroscopy to investigate both the translational and rotational contributions. Data on proton self-diffusion and reorentational correlation time indicate that the kinetics of the lysozyme fold- ing/unfolding process is controlled by the dynamics of the water molecules in the first hydration shell. When the hydration water dynamics change, because of the weakening of the hydrogen bond network, the three-dimensional structure of the lysozyme is lost and denaturation is triggered. Our data indicates that at temperatures above approximately 315 K, water behaves as a simple liquid and is no longer a good solvent.展开更多
Herein we study the different microscopic interactions occurring in water/methanol solutions at dif- ferent methanol molar fractions, using NMR spctroscopy. Temperature was found to determine which interaction dominat...Herein we study the different microscopic interactions occurring in water/methanol solutions at dif- ferent methanol molar fractions, using NMR spctroscopy. Temperature was found to determine which interaction dominates. It was found that the mixing between water and methanol is non-ideal because of the presence of interactions like hydrophobicity and hydrophilicity. These results indicate that the competition between hydrophilic and hydrophobic interactions is different in different thermal regions, and that the physical properties of the solution are determined by the character of the solution itself, which in turn depends on the mole fraction of methanol and on the temperature.展开更多
The hydrogen mean force from experimental neutron Compton profiles is derived using deep inelastic neutron scattering on amorphous and polycrystalline ice. The formalism of mean force is extended to probe its sensitiv...The hydrogen mean force from experimental neutron Compton profiles is derived using deep inelastic neutron scattering on amorphous and polycrystalline ice. The formalism of mean force is extended to probe its sensitivity to anharmonicity in the hydrogen-nucleus effective potential. The shape of the mean force for amorphous and polycrystalline ice is primarily determined by the anisotropy of the underlying quasi-harmonic effective potential. The data from amorphous ice show an additional curvature reflecting the more pronounced anharmonicity of the effective potential with respect to that of ice Ih.展开更多
文摘By and large the research communities today are not fully aware of the remarkable universality in the dynamic properties of many-body relaxation/diffusion processes manifested in experiments and simulations on condensed matter with diverse chemical compositions and physical structures. I shall demonstrate the universality first from the dynamic processes in glass-forming systems. This is reinforced by strikingly similar properties of different processes in contrasting interacting systems all having nothing to do with glass transition. The examples given here include glass-forming systems of diverse chemical compositions and physical structures, conductivity relaxation of ionic conductors（liquid, glassy, and crystalline）,translation and orientation ordered phase of rigid molecule, and polymer chain dynamics. Universality is also found in the change of dynamics when dimension is reduced to nanometer size in widely different systems. The remarkable universality indicates that many-body relaxation/diffusion is governed by fundamental physics to be unveiled. One candidate is classical chaos on which the coupling model is based, Universal properties predicted by this model are in accord with diverse experiments and simulations.
文摘The present study investigates the effect of a silver (Ag)-containing nanocomposite coating on Staphylococcus epidermidis adhesion and icaA gene expression. Bacterial interactions with organic coatings with and without Ag nanoclusters were assessed through a combination of both conventional phenotypic analysis, using microscopy, and genotypic analysis, using the relative reverse transcription Real-Time Polymerase Chain Reaction (RT-PCR). The results suggest that the incorporation of Ag in organic coatings can significantly decrease bacterial adhesion and viability with time, in comparison to the organic coating alone. The initial Ag release though at concentrations lower than the bactericidal, significantly increased icaA gene expression for the bacteria interacting with the Ag containing coating two hours post adhesion, especially under the higher shear rate. Stress-inducing conditions such as sub-bactericidal concentrations of Ag and high shear rate can therefore increase icaA expression, indicating that analysis of gene expression can not only refine our knowledge of bacterial-material interactions, but also yield novel biomarkers for potential use in assessing biomaterials antimicrobial performance.
基金supported by the European“DYES4EVER”(Demonstration of cyclodextrin techniques in treatment of waste water in textile industry to recover and reuse textile dyes,LIFE12 ENV/ES/000309)within the LIFE+2012 program“Environment Policy and Governance project application”.
文摘In recent years the development of chitosan (CH) based materials as useful adsorbent polymeric matrices is an expanding field in the area of adsorption science. Even though CH has been successfully used for dye removal from aqueous solutions due to its low cost, no considerations have been made about, for example, the effect of changing the pH of chitosan hydrogelor about the dehydrating effect of Ethanol (EtOH) treatment of chitosan film on the dyes removal from water. Consequently in our laboratory we carried out a study focusing the attention, mainly, on the potential use of CH films under different conditions, such as reducing the intrinsic pH, increasing the hydrophobic character by means of ethanol treatment and neutralization of CH films to improve their absorption power. Textile anionic dyes named Direct Red 83:1, Direct Yellow 86 and Direct Blue 78 have been studied with the aim of reducing the contact time of CH film in waste water improving the bleaching efficiency. Neutralized acid CH film and longtime dehydrated one result to be the better films in dye removal from water. Also the reduction of the CH solution acidity during the film preparation determines the decreasing of the contact time improving the results. The effect of initial dye concentration has been examined and the amount of dye adsorption in function of time t, qt (mg/cm2), for each analyzed film has been evaluated comparing the long term effect with the decoloration rate. A linear form of pseudo-first-order Lagergren model has been used and described. The best condition for removing all examined dyes from various dye solutions appears to be the dehydration of a novel projected CH film obtained by means of the film immersion in EtOH for 4 days. Also CH films prepared by well-known literature procedure and neutralized with NaOH treatment appear having an excellent behavior, however the film treatment requires a large quantity of water and time.
基金the support of the Project“Network 4 Energy Sustainable Transition─NEST”,Spoke 1,Project code PE0000021funded under the National Recovery and Resilience Plan(NRRP),Mission 4,Component 2,Investment 1.3-Cal for tender No.1561 of 11.10.2022 of Ministero del’Universita e del a Ricerca(MUR)funded by the European Union-Next Generation EU。
文摘Beyond traditional rooftop and building-integrated photovoltaics(BIPV),photovoltaic(PV)devices find applications in agrivoltaics,space,and indoor settings.However,the underwater(UW)environment remains largely unexplored.Below 50 m,the solar spectrum shifts dramatically,with only blue-green light(400–600 nm)available.Perovskite solar cells(PSCs),known for their high-power conversion efficiencies(PCEs)and tunable bandgaps,offer potential for this environment.Initially,simulations compared the intensity of the solar radiation based on three models,each based on a different water body,down to a depth of 10 m.
基金transnational EU project INCIPIT M-ERA.NET 2 call 2016,MIUR(DD n.1218,June 21,2019)FIRSTPoC Instrument-II cut-off 2020,Fondazione Compagnia di San Paolo(Compagnia di San Paolo Foundation)+4 种基金European Union-NextGenerationEU,Mission 4,Compo-nent 2,Investment 1.1,financed within PRIN 2022 D.D.n.10402-02-2022-2022ATB4TP-Innovative development of a cardiac patch in the industrialization phase for the activation of regenerative and pro-tective processes of cardiac ischemic issues,CUP D53D23013370006,B53D23020090006local funds RASR_RILO_23_01 and GIAC_RILO_23_02the contribution of Luca Munaron for assistance in electrophysiological experimental designRachele Rosso,Lelio Sciulli,Emanuela Vitale,Matteo Aubry,Marco Lo Iacono and Erika Fiorino for assistance in cellular and molecular analysesThe graphical abstract was in part created with BioRender.com.
文摘We produced a microstructured,electroconductive and nano-functionalized drug eluting cardiac patch(MEN-DEP)designed to attract endogenous precursor cells,favor their differentiation and counteract adverse ven-tricular remodeling in situ.MENDEP showed mechanical anisotropy and biaxial strength comparable to porcine myocardium,reduced impedance,controlled biodegradability,molecular recognition ability and controlled drug release activity.In vitro,cytocompatibility and cardioinductivity were demonstrated.Migration tests showed the chemoattractive capacity of the patches and conductivity assays showed unaltered cell-cell interactions and cell beating synchronicity.MENDEP was then epicardially implanted in a rat model of ischemia/reperfusion(I/R).Histological,immunofluorescence and biomarker analysis indicated that implantation did not cause damage to the healthy myocardium.After I/R,MENDEP recruited precursor cells into the damaged myocardium and triggered their differentiation towards the vascular lineage.Under the patch,the myocardial tissue appeared well preserved and cardiac gap junctions were correctly distributed at the level of the intercalated discs.The fibrotic area measured in the I/R group was partially reduced in the patch group.
文摘We report on the unconventional optical properties exhibited by a two-dimensional array of thin Si nanowires arranged in a random fractal geometry and fabricated using an inexpensive,fast and maskless process compatible with Si technology.The structure allows for a high light-trapping efficiency across the entire visible range,attaining total reflectance values as low as 0.1%when the wavelength in the medium matches the length scale of maximum heterogeneity in the system.We show that the random fractal structure of our nanowire array is responsible for a strong in-plane multiple scattering,which is related to the material refractive index fluctuations and leads to a greatly enhanced Raman scattering and a bright photoluminescence.These strong emissions are correlated on all length scales according to the refractive index fluctuations.The relevance and the perspectives of the reported results are discussed as promising for Si-based photovoltaic and photonic applications.
文摘The degradation process of cellulose-made materials was investigated by means of nuclear magnetic resonance （NMR） spectroscopy, with particular emphasis on the role of water and on the hydration mechanism of cellulose fibrils. To accomplish this, the structure and dynamics of water within ancient and modern samples with different aging histories were investigated. The results mainly indicated that hydrolytic and oxidative reactions provoked the formation of acidic by-products. Furthermore, degradation processes were enhanced by higher amounts of water giving a progressive consumption of the amorphous regions of the cellulose. We propose NMR experiments as a benchmark for character- ization of the degradation state of paper, as well as for investigating the effectiveness of restoration treatments.
基金support from the Swiss National Science Foundation(Sinergia Project,No.IZLIZ2_182972).
文摘Living photovoltaics are microbial electrochemical devices that use whole cell–electrode interactions to convert solar energy to electricity.The bottleneck in these technologies is the limited electron transfer between the microbe and the electrode surface.This study focuses on enhancing this transfer by engineering a polydopamine(PDA)coating on the outer membrane of the photosynthetic microbe Synechocystis sp.PCC6803.This coating provides a conductive nanoparticle shell to increase electrode adhesion and improve microbial charge extraction.A combination of scanning electron microscopy(SEM),transmission electron microscopy(TEM),UV–Vis absorption,and Raman spectroscopy measurements were used to characterize the nanoparticle shell under various synthesis conditions.The cell viability and activity were further assessed through oxygen evolution,growth curve,and confocal fluorescence microscopy measurements.The results show sustained cell growth and detectable PDA surface coverage under slightly alkaline conditions(pH 7.5)and at low initial dopamine(DA)concentrations(1 mM).The exoelectrogenicity of the cells prepared under these conditions was also characterized through cyclic voltammetry(CV)and chronoamperometry(CA).The measurements show a three-fold enhancement in the photocurrent at an applied bias of 0.3 V(vs.Ag/AgCl[3 M KCl])compared to non-coated cells.This study thus lays the framework for engineering the next generation of living photovoltaics with improved performances using biosynthetic electrodes.
文摘The self-assembling properties, stability, and dynamics of hybrid nanocarriers （gold nanoparticles （AuNPs） functionalized with cysteine-based peptides） in solution are studied through a series of classical molecular dynamics simulations based on a recently parametrized reactive force field. The results reveal, at the atomic level, all the details regarding the peptide adsorption mechanisms, nanoparticle stabilization, aggregation, and sintering. The data confirm and explain the experimental findings and disclose aspects that cannot be scrutinized by experiments. The biomolecules are both chemisorbed and physisorbed; self-interactions of the adsorbates and formation of stable networks of inter- connected molecules on the AuNP surfaces limit substrate reconstructions, protect the AuNPs from the action of the solvent, and prevent direct interactions of the gold surfaces. The possibility of agglomeration of the functionalized nanoparticles, compared with the sintering of the bare supports in a water solution, is demonstrated through relatively long simulations and fast steered dynamics. The analysis of the trajectories reveals that the AuNPs were well stabilized by the peptides. This prevented particle sintering and kept the particles far apart; however, part of their chains could form interconnections （crosslinks） between neighboring gold vehicles. The excellent agreement of these results with the literature confirm the reliability of the method and its potential application to the modeling of more complex materials relevant to the biomedical sector.
基金A.R.,G.L.and A.G.thank the University of Catania(Piano della Ricerca di Ateneo 2016-2018)for partial financial supportG.R.and C.A.thank ITN-ETN Horizon 2020 Project ModCompShock,Modeling and Computation on Shocks and Interfaces,Project Reference 642768the Italian Ministry of Instruction,University and Research(MIUR)to support this research with funds coming fromPRIN Project 2017(No.2017KKJP4X)entitled"Innovative numerical methods for evolutionary partial differential equations and applications".
文摘In this paper we propose a computational framework for the investigation of the correlated motion between positive and negative ions exposed to the attraction of a bubble surface that mimics the(oscillating)cell membrane.Specifically we aim to investigate the role of surface traps with substances freely diffusing around the cell.The physical system we want to model is an anchored gas drop submitted to a diffusive flowof charged surfactants(ions).When the diffusing surfactantsmeet the surface of the bubble,they are reversibly adsorbed and their local concentration is accurately measured.The correlated diffusion of surfactants is described by a Poisson-Nernst-Planck(PNP)system,in which the drift term is given by the gradient of a potential which includes both the effect of the bubble and the Coulomb interaction between the carriers.The latter term is obtained from the solution of a self-consistent Poisson equation.For very short Debye lengths one can adopt the so called Quasi-Neutral limit which drastically simplifies the system,thus allowing for much faster numerical simulations.The paper has four main objectives.The first one is to present a PNP model that describes ion charges in presence of a trap.The second one is to provide benchmark tests for the validation of simplified multiscale models under current development[1].The third one is to explore the relevance of the term describing the interaction among the apolar tails of the anions.The last one is to quantitatively explore the validity of the Quasi-Neutral limit by comparison with detailed numerical simulation for smaller and smaller Debye lengths.In order to reach these goals,we propose a simple and efficient Alternate Direction Implicit method for the numerical solution of the non-linear PNP system,which guarantees second order accuracy both in space and time,without requiring solution of nonlinear equation at each time step.New semi-implicit scheme for a simplified PNP system near quasi neutrality is also proposed.
文摘The spatial domain of Molecular Dynamics simulations is usually a regular box that can be easily divided in subdomains for parallel processing.Recent efforts aimed at simulating complex biological systems,like the blood flow inside arteries,require the execution of Parallel Molecular Dynamics(PMD)in vessels that have,by nature,an irregular shape.In those cases,the geometry of the domain becomes an additional input parameter that directly influences the outcome of the simulation.In this paper we discuss the problems due to the parallelization of MD in complex geometries and show an efficient and general method to perform MD in irregular domains.
基金supported by the framework of past and present(2014-2020)agreements between the CNRthe STFC for collaborative research between Italy and ISIS
文摘Water properties are dominated by the hydrogen bond interaction that gives rise in the stable liquid phase to the formation of a dynamical network.The latter drives the water thermodynamics and is at the origin of its well known anomalies.The HB structural geometry and its changes remain uncertain and still are challenging research subjects.A key question is the role and effects of the HB tetrahedral structure on the local arrangement of neighboring molecules in water.Here the hydrogen dynamics in bulk water is studied through the combined use of Neutron Compton Scattering and NMR techniques.Results are discussed in the framework of previous studies performed in a wide temperature range,in the liquid,solid,and amorphous states.For the first time this combined studies provide an experimental evidence of the onset of the water tetrahedral network at T^315 K,originally proposed in previous studies of transport coefficients and thermodynamical data;below this temperature the local order in water changes and the lifetime of local hydrogen bond network becomes long enough to gradually develop the characteristic tetrahedral network of water.
文摘We study the dynanfics of the first hydration shell of lysozyme to determine the role of hydra- tion water that accompanies lysozyme thermal denaturation. We use nuclear magnetic resonance spectroscopy to investigate both the translational and rotational contributions. Data on proton self-diffusion and reorentational correlation time indicate that the kinetics of the lysozyme fold- ing/unfolding process is controlled by the dynamics of the water molecules in the first hydration shell. When the hydration water dynamics change, because of the weakening of the hydrogen bond network, the three-dimensional structure of the lysozyme is lost and denaturation is triggered. Our data indicates that at temperatures above approximately 315 K, water behaves as a simple liquid and is no longer a good solvent.
文摘Herein we study the different microscopic interactions occurring in water/methanol solutions at dif- ferent methanol molar fractions, using NMR spctroscopy. Temperature was found to determine which interaction dominates. It was found that the mixing between water and methanol is non-ideal because of the presence of interactions like hydrophobicity and hydrophilicity. These results indicate that the competition between hydrophilic and hydrophobic interactions is different in different thermal regions, and that the physical properties of the solution are determined by the character of the solution itself, which in turn depends on the mole fraction of methanol and on the temperature.
文摘The hydrogen mean force from experimental neutron Compton profiles is derived using deep inelastic neutron scattering on amorphous and polycrystalline ice. The formalism of mean force is extended to probe its sensitivity to anharmonicity in the hydrogen-nucleus effective potential. The shape of the mean force for amorphous and polycrystalline ice is primarily determined by the anisotropy of the underlying quasi-harmonic effective potential. The data from amorphous ice show an additional curvature reflecting the more pronounced anharmonicity of the effective potential with respect to that of ice Ih.
