Author
Marian Paluch
Other affiliations: Silesian University of Technology, Complutense University of Madrid, Max Planck Society ...read more
Bio: Marian Paluch is an academic researcher from University of Silesia in Katowice. The author has contributed to research in topics: Glass transition & Relaxation (physics). The author has an hindex of 54, co-authored 594 publications receiving 13940 citations. Previous affiliations of Marian Paluch include Silesian University of Technology & Complutense University of Madrid.
Papers published on a yearly basis
Papers
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TL;DR: This work identifies the class of secondary relaxations that bears a strong connection or correlation to the primary relaxation in all the dynamic properties and proposes that only these should be called the Johari-Goldstein beta-relaxation.
Abstract: Dynamic properties, derived from dielectric relaxation spectra of glass-formers at variable temperature and pressure, are used to characterize and classify any resolved or unresolved secondary relaxation based on their different behaviors. The dynamic properties of the secondary relaxation used include: (1) the pressure and temperature dependences; (2) the separation between its relaxation time τβ and the primary relaxation time τα at any chosen τα; (3) whether τβ is approximately equal to the independent (primitive) relaxation time τ0 of the coupling model; (4) whether both τβ and τ0 have the same pressure and temperature dependences; (5) whether it is responsible for the “excess wing” of the primary relaxation observed in some glass-formers; (6) how the excess wing changes on aging, blending with another miscible glass-former, or increasing the molecular weight of the glass-former; (7) the change of temperature dependence of its dielectric strength Δeβ and τβ across the glass transition temperature Tg; ...
715 citations
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TL;DR: In this paper, a review of the mechanisms underlying the relaxation properties of glass-forming liquids and polymers is provided, with an emphasis in the insight provided into the mechanism underlying the glass relaxation properties.
Abstract: An intriguing problem in condensed matter physics is understanding the glass transition, in particular the dynamics in the equilibrium liquid close to vitrification Recent advances have been made by using hydrostatic pressure as an experimental variable These results are reviewed, with an emphasis in the insight provided into the mechanisms underlying the relaxation properties of glass-forming liquids and polymers
638 citations
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TL;DR: It is an unlikely result that the dispersion of the structural relaxation would be uniquely defined by taualpha, but the shape of the alpha-relaxation function depends only on the relaxation time.
Abstract: Upon decreasing temperature or increasing pressure, a noncrystallizing liquid will vitrify; that is, the structural relaxation time, τα, becomes so long that the system cannot attain an equilibrium configuration in the available time. Theories, including the well-known free volume and configurational entropy models, explain the glass transition by invoking a single quantity that governs the structural relaxation time. The dispersion of the structural relaxation (i.e., the structural relaxation function) is either not addressed or is derived as a parallel consequence (or afterthought) and thus is independent of τα. In these models the time dependence of the relaxation bears no fundamental relationship to the value of τα or other dynamic properties. Such approaches appear to be incompatible with a general experimental fact recently discovered in glass-formers: for a given material at a fixed value of τα, the dispersion is constant, independent of thermodynamic conditions (T and P); that is, the shape of th...
212 citations
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TL;DR: In this paper, the electrical properties of disordered perovskite-like ceramics in a wide temperature range were investigated by using the x-ray diffraction analysis.
Abstract: Broadband dielectric spectroscopy is applied to investigate the electrical properties of disordered perovskite-like ceramics in a wide temperature range. From the x-ray diffraction analysis it was found that the newly obtained (Na0.75Bi0.25) (Mn0.25Nb0.75)O3 ceramics consist of two chemically different phases. The major perovskite one has an orthorhombic structure described by the Pbcm space group (No 57, in yxz setting). The minor phase shows an orthorhombic symmetry, all-face-centred lattice F, with the lattice parameters a = 10.797(4) A, b = 7.601(3) A and c = 7.691(3) A. The electric modulus M* formalism used in the analysis enabled us to distinguish and separate the relaxation processes, dominated by marked conductivity in the e*(ω) representation. In the ceramics studied, the relaxation times are thermally activated and the dipole process has a clearly non-Debye behaviour. The relaxation process described with the use of the activation energy of approximately 0.4 eV and the characteristic relaxation time, τ0 = 1 × 10−11 s, was found to be related to oxygen vacancies. The low frequency relaxation shows Debye behaviour with a slightly lower activation energy and a longer characteristic time.
210 citations
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TL;DR: It is found that in sorbitol the dynamics of the whole molecule contributes equally to the beta process, while in glycerol the hydrogen bond forming OH groups remain rather rigid compared to the hydrogens bonded to the carbon skeleton.
Abstract: We have studied details of the molecular origin of slow secondary relaxation near T(g) in a series of neat polyalcohols by means of dielectric spectroscopy and (2)H NMR. From glycerol to threitol, xylitol, and sorbitol the appearance of the secondary relaxation changes gradually from a wing-type scenario to a pronounced beta peak. It is found that in sorbitol the dynamics of the whole molecule contributes equally to the beta process, while in glycerol the hydrogen bond forming OH groups remain rather rigid compared to the hydrogens bonded to the carbon skeleton.
182 citations
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TL;DR: The article provides an integrated and contemporary discussion of current approaches to solubility and dissolution enhancement but has been deliberately structured as a series of stand-alone sections to allow also directed access to a specific technology where required.
Abstract: Drugs with low water solubility are predisposed to low and variable oral bioavailability and, therefore, to variability in clinical response. Despite significant efforts to "design in" acceptable developability properties (including aqueous solubility) during lead optimization, approximately 40% of currently marketed compounds and most current drug development candidates remain poorly water-soluble. The fact that so many drug candidates of this type are advanced into development and clinical assessment is testament to an increasingly sophisticated understanding of the approaches that can be taken to promote apparent solubility in the gastrointestinal tract and to support drug exposure after oral administration. Here we provide a detailed commentary on the major challenges to the progression of a poorly water-soluble lead or development candidate and review the approaches and strategies that can be taken to facilitate compound progression. In particular, we address the fundamental principles that underpin the use of strategies, including pH adjustment and salt-form selection, polymorphs, cocrystals, cosolvents, surfactants, cyclodextrins, particle size reduction, amorphous solid dispersions, and lipid-based formulations. In each case, the theoretical basis for utility is described along with a detailed review of recent advances in the field. The article provides an integrated and contemporary discussion of current approaches to solubility and dissolution enhancement but has been deliberately structured as a series of stand-alone sections to allow also directed access to a specific technology (e.g., solid dispersions, lipid-based formulations, or salt forms) where required.
1,201 citations
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TL;DR: In this paper, the authors reviewed the basic characteristics of the liquid-glass transition, emphasizing its universality and briefly summarizing the most popular phenomenological models, focusing on a number of alternative models which one way or the other connect the fast and slow degrees of freedom of viscous liquids.
Abstract: Basic characteristics of the liquid-glass transition are reviewed, emphasizing its universality and briefly summarizing the most popular phenomenological models. Discussion is focused on a number of alternative models which one way or the other connect the fast and slow degrees of freedom of viscous liquids. It is shown that all these ``elastic'' models are equivalent in the simplest approximation.
1,080 citations
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TL;DR: The accumulated data on the biological activity of ionic liquids, including their antimicrobial and cytotoxic properties, are discussed in view of possible applications in drug synthesis and drug delivery systems.
Abstract: Ionic liquids are remarkable chemical compounds, which find applications in many areas of modern science. Because of their highly tunable nature and exceptional properties, ionic liquids have become essential players in the fields of synthesis and catalysis, extraction, electrochemistry, analytics, biotechnology, etc. Apart from physical and chemical features of ionic liquids, their high biological activity has been attracting significant attention from biochemists, ecologists, and medical scientists. This Review is dedicated to biological activities of ionic liquids, with a special emphasis on their potential employment in pharmaceutics and medicine. The accumulated data on the biological activity of ionic liquids, including their antimicrobial and cytotoxic properties, are discussed in view of possible applications in drug synthesis and drug delivery systems. Dedicated attention is given to a novel active pharmaceutical ingredient-ionic liquid (API-IL) concept, which suggests using traditional drugs in ...
1,065 citations