Showing papers by "Sylwester J. Rzoska published in 2014"
TL;DR: The densification of these glasses is found to occur at temperatures much below the glass transition temperature, indicating that a non-viscous mechanism is at play, and density relaxes in a stretched exponential manner upon subsequent annealing at ambient pressure with an exponent of ∼0.62.
Abstract: The mixed modifier effect (MME) in oxide glasses manifests itself as a non-additive variation in certain properties when one modifier oxide species is substituted by another one at constant total modifier content. However, the structural and topological origins of the MME are still under debate. This study provides new insights into the MME by investigating the effect of isostatic compression on density and hardness of mixed MgO/CaO sodium aluminosilicate glasses. This is done using a specially designed setup allowing isostatic compression of bulk glass samples up to 1 GPa at elevated temperature. A mixed alkaline earth effect is found in the compressibility and relative change of hardness, viz., a local maximum of density as a function of Mg/Ca ratio appears following compression, whereas a local minimum of hardness in the uncompressed glasses nearly disappears after compression. Moreover, the densification of these glasses is found to occur at temperatures much below the glass transition temperature, indicating that a non-viscous mechanism is at play. This is further supported by the fact that density relaxes in a stretched exponential manner upon subsequent annealing at ambient pressure with an exponent of ∼0.62. This is close to the Phillips value of 3/5 for relaxation in three dimensions when both short- and long-range interactions are activated.
50 citations
TL;DR: In this paper, the authors reveal a linear dependence of the plastic compressibility of borosilicate glasses on both initial trigonal boron content and relative change in hardness with pressure, with important implications for manufacturing tailored damage resistant glassy materials.
Abstract: Glass is ubiquitous, yet our understanding of its structure-function relationships remains far from complete and limits technology. For example, while compression is an important tool in the synthesis of crystalline materials, comparable breakthroughs in preparing bulk glasses are still largely lacking. This work reveals the striking linear dependence of the plastic compressibility of borosilicate glasses on both initial trigonal boron content and relative change in hardness with pressure, with important implications for manufacturing tailored damage-resistant glassy materials.
46 citations
TL;DR: Cells exposed to different physical and chemical treatments, including high hydrostatic pressure (HHP), suffer from injuries that could be reversible in food materials when stored.
Abstract: Cells exposed to different physical and chemical treatments, including high hydrostatic pressure (HHP), suffer from injuries that could be reversible in food materials when stored. Escherichia coli and Listeria innocua cells suspended in phosphate-buffered saline (PBS) (model suspensions), and acidified beetroot juice were subjected to a pressure of 400 MPa at a temperature of 20°C for up to 10 min. The difference between the viable and non-injured cells was used to estimate the number of injured survivors.The reduction in E. coli cell number was 3.4–4.1 log after 10 min pressurization in model suspensions and 6.2 log in beetroot juice. Sublethally injured cells in PBS accounted for up to 2.7 log after 10 min HHP treatment and 0.8 log in beetroot juice. The reduction in L. innocua cell number after 10 min pressure treatment reached from 3.8 to 4.8 log, depending on the initial concentration in model suspensions. Among the surviving L. innocua cells, even up to 100% were injured. L. innocua cells were comp...
34 citations
TL;DR: In this paper, a specially designed gas pressure chamber is employed to compress bulk glass samples isostatically up to 1.5 times the ambient pressure, and the interplay among isostatic compression, pressure-induced changes in alkali diffusivity, compressive stress generated through ion exchange, and resulting mechanical properties are poorly understood.
Abstract: Glass exhibits a significant change in properties when subjected to high pressure because the short- and intermediate-range atomic structures of glass are tunable through compression. Understanding the link between the atomic structure and macroscopic properties of glass under high pressure is an important scientific problem because the glass structures obtained via quenching from elevated pressure may give rise to properties unattainable under standard ambient pressure conditions. In particular, the chemical strengthening of glass through K+-for-Na+ ion exchange is currently receiving significant interest due to the increasing demand for stronger and more damage-resistant glass. However, the interplay among isostatic compression, pressure-induced changes in alkali diffusivity, compressive stress generated through ion exchange, and the resulting mechanical properties are poorly understood. In this work, we employ a specially designed gas pressure chamber to compress bulk glass samples isostatically up to ...
25 citations
TL;DR: It is shown that the positive sign of NDE in DEE is also possible, in the supercritical domain, and NDE on approaching the gas-liquid critical point exhibits a unique critical effect described by the critical exponent.
Abstract: Nonlinear dielectric effect (NDE) describes changes of dielectric permittivity induced by a strong electric field in a liquid dielectric. The most classical finding related to this magnitude is the negative sign of NDE in liquid diethyl ether (DEE), recalled by Peter Debye in his Nobel Prize lecture. This article shows that the positive sign of NDE in DEE is also possible, in the supercritical domain. Moreover, NDE on approaching the gas-liquid critical point exhibits a unique critical effect described by the critical exponent ψ ≈ 0.4 close to critical temperature (T C) and ψ ≈ 0.6 remote from T C . This can be linked to the emergence of the mean-field behavior in the immediate vicinity of T C , contrary to the typical pattern observed for critical phenomena. The multi-frequency mode of NDE measurements made it possible to estimate the evolution of lifetime of critical fluctuations. The new way of data analysis made it possible to describe the critical effect without a knowledge of the non-critical background contribution in prior.
18 citations
Posted Content•
TL;DR: In this paper, the Debye-Stokes-Einstein relation FDSE sigma times tau to the power S equals const, where tau and sigma are for the structural relaxation time and electric conductivity are functions of T and P, respectively.
Abstract: Orientational and translational decouplings in ultraviscous glass forming glycerol and its nanocolloid based on Ag nanoparticles, as the function of temperature and pressure up to challenging P more than 1.5 GPa, are discussed. The analysis is focused on the fractional Debye-Stokes-Einstein relation FDSE sigma times tau to the power S equals const., where tau and sigma are for the structural relaxation time and electric conductivity are functions of T and P, respectively. For temperature tests in glycerol the clear evidence for the almost coupled exponent S equals 1 was obtained. For the supercooled nanocolloid the crossover to the decoupled domain associated with S equals 0.91 was noted. In super pressed glycerol and the nanocolloid the clear cross over from the domain described by the exponent S equals 1 to S less than 1 appeared on the GPa domain. For the nanocolloid it is associated with particularly strong decoupling, related to S equals 0.5, and occurs at well-defined pressure. This can suggest a possible fluid-fluid transition. Questions related to the validity of the Debye-Stokes tau equals approx. eta over T and Maxwell tau equals approx. eta relations, where eta is for viscosity, are also addressed. Results obtained do not support the recently suggested universality of the fractional exponent describing orientational and translational decoupling.