The European Physical Journal E最新文献

{"title":"The Soret coefficient of human low-density lipoprotein in solution: a thermophilic behavior","authors":"Luciene Oliveira Machado,&nbsp;Dennys Reis,&nbsp;Antônio Martins Figueiredo Neto","doi":"10.1140/epje/s10189-023-00377-5","DOIUrl":"10.1140/epje/s10189-023-00377-5","url":null,"abstract":"<div><p>Thermodiffusion, or Soret effect, is the physical phenomenon of matter gradients originated by the migration of chemical species induced by thermal gradients. Thermodiffusion has been widely applied in the study of colloidal suspensions. In this study, we investigate the termodiffusion behavior of low-density lipoprotein (LDL) particles, by the Soret coefficient measurement. It is a new approach to studies of plasma lipoproteins. The experimental work was based on thermal- and Soret-lens effects. These effects were induced by laser irradiation of the samples, at two different time scales, in a Z-scan setup. LDL samples were analyzed under physiological conditions, notedly, ionic strength and pH, and at different temperatures. Temperature dependence of Soret coefficient showed a slight decrease in the absolute value of this coefficient, as a function of temperature increasing. However, its sign does not change at the temperatures investigated (15, 22.5 and 37.5 °C). The results show that LDL particles exhibit thermophilic behavior. The origin of this thermophilic behavior is not yet completely understood. We discuss some aspects that can be related with the Soret effect in LDL samples.</p><h3>Graphical abstract</h3><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"46 12","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138497467","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Statics and dynamics of point boojums, line and modified Saturn ring topological defects in nematic confined geometry","authors":"P. V. Dolganov,&nbsp;N. A. Spiridenko,&nbsp;V. K. Dolganov","doi":"10.1140/epje/s10189-023-00387-3","DOIUrl":"10.1140/epje/s10189-023-00387-3","url":null,"abstract":"<div><p>In this paper we study the static structure and the dynamics of topological defects associated with isotropic droplets in nematic environment. Investigations were made in confined geometry of optical cells when the droplet size was of the order of or larger than the gap of the cell. We observed the coexistence of point boojums and Saturn ring or modified Saturn ring defects. We found transformation of the Saturn ring defect to two localized broad defects at increasing the droplet size. At droplet coalescence antipodes of point and localized broad defects were born and the dynamics of their annihilation with existing defects was investigated. We found strong difference in the process of annihilation of point and localized broad defects.</p><h3>Graphical Abstract</h3><div><figure><div><div><picture><source><img></source></picture></div><div><p>Microscope images of isotropic droplets in nematic environment in a planar cell. The director orientation far from the droplets is in horizontal direction. The photographs were taken with crossed vertical and horizontal polarizers (<b>a</b>) and with a single horizontal polarizer (<b>b</b>). The cell thickness is 100 μm. Droplet diameter is less than the cell thickness. 1 and 2 are point boojums, L is the Saturn ring defect</p></div></div></figure></div></div>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"46 12","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epje/s10189-023-00387-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138497466","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Induced phase transformation in ionizable colloidal nanoparticles","authors":"Leticia López-Flores,&nbsp;Monica Olvera de la Cruz","doi":"10.1140/epje/s10189-023-00386-4","DOIUrl":"10.1140/epje/s10189-023-00386-4","url":null,"abstract":"<p>Acid–base equilibria directly influence the functionality and behavior of particles in a system. Due to the ionizing effects of acid–base functional groups, particles will undergo charge exchange. The degree of ionization and their intermolecular and electrostatic interactions are controlled by varying the pH and salt concentration of the solution in a system. Although the pH can be tuned in experiments, it is hard to model this effect using simulations or theoretical approaches. This is due to the difficulty in treating charge regulation and capturing the cooperative effects in a colloidal suspension with Coulombic interaction. In this work, we analyze a suspension of ionizable colloidal particles via molecular dynamics (MD) simulations, along with Monte Carlo simulations for charge regulation (MC-CR) and derive a phase diagram of the system as a function of pH. It is observed that as pH increases, particles functionalized with acid groups change their arrangement from face-centered cubic (FCC) packing to a disordered state. We attribute these transitions to an increase in the degree of charge polydispersity arising from an increase in pH. Our work shows that charge regulation leads to amorphous solids in colloids when the mean nanoparticle charge is sufficiently high.</p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"46 12","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epje/s10189-023-00386-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138497464","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Lipid vesicle pools studied by passive X-ray microrheology","authors":"Titus Czajka,&nbsp;Charlotte Neuhaus,&nbsp;Jette Alfken,&nbsp;Moritz Stammer,&nbsp;Yuriy Chushkin,&nbsp;Diego Pontoni,&nbsp;Christian Hoffmann,&nbsp;Dragomir Milovanovic,&nbsp;Tim Salditt","doi":"10.1140/epje/s10189-023-00375-7","DOIUrl":"10.1140/epje/s10189-023-00375-7","url":null,"abstract":"<p>Vesicle pools can form by attractive interaction in a solution, mediated by proteins or divalent ions such as calcium. The pools, which are alternatively also denoted as vesicle clusters, form by liquid-liquid phase separation (LLPS) from an initially homogeneous solution. Due to the short range liquid-like order of vesicles in the pool or cluster, the vesicle-rich phase can also be regarded as a condensate, and one would like to better understand not only the structure of these systems, but also their dynamics. The diffusion of vesicles, in particular, is expected to change when vesicles are arrested in a pool. Here we investigate whether passive microrheology based on X-ray photon correlation spectroscopy (XPCS) is a suitable tool to study model systems of artificial lipid vesicles exhibiting LLPS, and more generally also other heterogeneous biomolecular fluids. We show that by adding highly scattering tracer particles to the solution, valuable information on the single vesicle as well as collective dynamics can be inferred. While the correlation functions reveal freely diffusing tracer particles in solutions at low CaCl<span>(_{2})</span> concentrations, the relaxation rate <span>(Gamma (q))</span> shows a nonlinear dependence on <span>(q^2)</span> at a higher concentration of around 8 mM CaCl<span>(_{2})</span>, characterised by two linear regimes with a broad cross-over. We explain this finding based on arrested diffusion in percolating vesicle clusters.</p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"46 12","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epje/s10189-023-00375-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138497465","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Connection number topological aspect for backbone DNA networks","authors":"Ali Ahmad,&nbsp;Ali N. A. Koam,&nbsp;Ibtisam Masmali,&nbsp;Muhammad Azeem,&nbsp;Haleemah Ghazwani","doi":"10.1140/epje/s10189-023-00381-9","DOIUrl":"10.1140/epje/s10189-023-00381-9","url":null,"abstract":"<p>The present study investigates the complex topological characteristics of DNA networks, with a specific emphasis on the innovative metric known as Connection Number (CN) as a key factor in determining network structure. The Connection Number, represented as <i>CN</i>(<i>v</i>) for a vertex <i>v</i>, measures the count of unique paths that link <i>v</i> to every other vertex in the network. By employing rigorous mathematical modeling and analysis techniques, we are able to reveal the profound implications of CN (complex networks) in characterizing the structural robustness and dynamics of information flow within DNA networks. The study of how the theory of graphs and chemicals interact is known as chemical graph theory. This paper, computing the hyper Zagreb connection index, augmented connection index, inverse sum connection index, harmonic connection index, symmetric division connection index, geometric arithmetic connection index, and atom bond connectivity connection index, of two significant types of backbone DNA and Barycentric subdivision of backbone DNA networks. Direct method computation is used to produce these Connection-based topological descriptors.</p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"46 12","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epje/s10189-023-00381-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138486369","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spontaneous bilayer wrapping of virus particles by a phospholipid Langmuir monolayer","authors":"J. F. Torres-Salgado,&nbsp;M. V. Villagrana-Escareño,&nbsp;A. L. Duran-Meza,&nbsp;X. F. Segovia-Gonzalez,&nbsp;R. D. Cadena-Nava,&nbsp;W. M. Gelbart,&nbsp;C. M. Knobler,&nbsp;J. Ruiz-García","doi":"10.1140/epje/s10189-023-00366-8","DOIUrl":"10.1140/epje/s10189-023-00366-8","url":null,"abstract":"<div><p>We report here the spontaneous formation of lipid-bilayer-wrapped virus particles, following the injection of “naked” virus particles into the subphase of a Langmuir trough with a liquid monolayer of lipids at its air–water interface. The virus particles are those of the well-studied cowpea chlorotic mottle virus, CCMV, which are negatively charged at the pH 6 of the subphase; the lipids are a 9:1 mix of neutral DMPC and cationic CTAB molecules. Before adding CCMV particles to the subphase we establish the mixed lipid monolayer in its liquid-expanded state at a fixed pressure (17.5 mN/m) and average area-per-molecule of (41Ų). Keeping the total area fixed, the surface pressure is observed to decrease at about 15 h after adding the virus particles in the subphase; by 37 h it has dropped to zero, corresponding to essentially all the lipid molecules having been removed from the air–water interface. By collecting particles from the subphase and measuring their sizes by atomic force microscopy, we show that the virus particles have been wrapped by lipid bilayers (or by two lipid bilayers). These results can be understood in terms of thermal fluctuations and electrostatic interactions driving the wrapping of the anionic virus particles by the cationic lipids.</p><h3>Graphical Abstract</h3><div><figure><div><div><picture><source><img></source></picture></div><div><p>Spontaneous acquisition by a virus particle of, first, a hydrophobic lipid monolayer envelope and, then, a hydrophilic lipid bilayer envelope, as it interacts from the subphase with an oppositely charged Langmuir monolayer</p></div></div></figure></div></div>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"46 12","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epje/s10189-023-00366-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138486371","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effective interactions and phase behavior of protein solutions in the presence of hexamine cobalt(III) chloride","authors":"Maximilian D. Senft,&nbsp;Ralph Maier,&nbsp;Anusha Hiremath,&nbsp;Fajun Zhang,&nbsp;Frank Schreiber","doi":"10.1140/epje/s10189-023-00376-6","DOIUrl":"10.1140/epje/s10189-023-00376-6","url":null,"abstract":"<div><p>It is well established that deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) exhibit a reentrant condensation (RC) phase behavior in the presence of the trivalent hexamine cobalt(III) cations (Hac) which can be important for their packing and folding. A similar behavior can be observed for negatively charged globular proteins in the presence of trivalent metal cations, such as Y³⁺ or La³⁺. This phase behavior is mainly driven by charge inversion upon an increasing salt concentration for a fixed protein concentration (<i>c</i>_p). However, as Hac exhibits structural differences compared to other multivalent metal cations, with six ammonia ligands (NH₃) covalently bonded to the central cobalt atom, it is not clear that Hac can induce a similar phase behavior for proteins. In this work, we systematically investigate whether negatively charged globular proteins β-lactoglobulin (BLG), bovine serum albumin (BSA), human serum albumin (HSA) and ovalbumin (OVA) feature Hac-induced RC. Effective protein–protein interactions were investigated by small-angle X-ray scattering. The reduced second virial coefficient (B₂/B₂^HS) was obtained as a function of salt concentration. The virial coefficient analysis performed confirms the reentrant interaction (RI) behavior for BLG without actually inducing RC, given the insufficient strengths of the interactions for the latter to occur. In contrast, the strength of attraction for BSA, HSA and OVA are too weak to show RC. Model free analysis of the inverse intensity <span>(1/Ileft( {q to 0} right))</span> also supports this finding. Looking at different <i>q</i>-range by employing static (SLS) and dynamic light scattering experiments, the presence of RI behavior can be confirmed. The results are further discussed in view of metal cation binding sites in nucleic acids (DNA and RNA), where Hac induced RC phase behavior.</p><h3>Graphical abstract</h3>\u0000<div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"46 12","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1140/epje/s10189-023-00376-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138486370","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Chilling alcohol on the computer: isothermal compressibility and the formation of hydrogen-bond clusters in liquid propan-1-ol","authors":"Luis A. Baptista,&nbsp;Mauricio Sevilla,&nbsp;Manfred Wagner,&nbsp;Kurt Kremer,&nbsp;Robinson Cortes-Huerto","doi":"10.1140/epje/s10189-023-00380-w","DOIUrl":"10.1140/epje/s10189-023-00380-w","url":null,"abstract":"<p>Molecular dynamics simulations have been performed to compute the isothermal compressibility <span>(kappa _T)</span> of liquid propan-1-ol in the temperature range <span>(200 le Tle 300)</span> K. A change in behaviour, from normal (high <i>T</i>) to anomalous (low <i>T</i>), has been identified for <span>(kappa _T)</span> at <span>(210&lt;T&lt;230)</span> K. The average number of hydrogen bonds (H–bond) per molecule turns to saturation in the same temperature interval, suggesting the formation of a relatively rigid network. Indeed, simulation results show a strong tendency to form H–bond clusters with distinct boundaries, with the average largest size and width of the size distribution growing upon decreasing temperature, in agreement with previous theoretical and experimental studies. These results also emphasise a connection between the behaviour of <span>(kappa _T)</span> and the formation of nanometric structures.</p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"46 11","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10687148/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138450677","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Electrostatic interactions between charge regulated spherical macroions","authors":"Hu Ruixuan,&nbsp;Arghya Majee,&nbsp;Jure Dobnikar,&nbsp;Rudolf Podgornik","doi":"10.1140/epje/s10189-023-00373-9","DOIUrl":"10.1140/epje/s10189-023-00373-9","url":null,"abstract":"<p>We study the interaction between two charge regulating spherical macroions with dielectric interior and dissociable surface groups immersed in a monovalent electrolyte solution. The charge dissociation is modelled via the Frumkin-Fowler-Guggenheim isotherm, which allows for multiple adsorption equilibrium states. The interactions are derived from the solutions of the mean-field Poisson-Boltzmann type theory with charge regulation boundary conditions. For a range of conditions we find symmetry breaking transitions from symmetric to asymmetric charge distribution exhibiting annealed charge patchiness, which results in like-charge attraction even in a univalent electrolyte—thus fundamentally modifying the nature of electrostatic interactions in charge-stabilized colloidal suspensions.</p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"46 11","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138450678","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Surface tension between liquids containing antagonistic and regular salts","authors":"Roni Kroll,&nbsp;Moshe Gottlieb,&nbsp;Yoav Tsori","doi":"10.1140/epje/s10189-023-00378-4","DOIUrl":"10.1140/epje/s10189-023-00378-4","url":null,"abstract":"<p>We investigate theoretically the surface tension between two immiscible liquids containing antagonistic and regular salts. The mean-field model includes the electrostatic energy and the Gibbs transfer energy of the ions. We find the Donnan potential difference between the liquids and solve the Poisson–Boltzmann equation to calculate the potential and ion density profiles. When the liquids contain only a regular salt, the surface tension increases when compared to the no-salt case; in contrast, the surface tension is reduced when they contain only an antagonistic salt. When both salts are present, the surface tension can either further decrease or increase depending on the preferential solvation of the ions, in agreement with published experimental observations.</p>","PeriodicalId":790,"journal":{"name":"The European Physical Journal E","volume":"46 11","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138450679","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}