The dynamics of supercooled ortho-terphenyl has been studied using photon-correlation spectroscopy (PCS) in the depolarized scattering geometry. The obtained relaxation curves are analyzed according to the mode-coupling theory (MCT) for supercooled liquids. The main results are: i) the observation of the secondary Johari-Goldstein relaxation (β) that has its onset just at the dynamical crossover temperature TB (TM > TB > Tg); ii) the confirmation, of the suggestion of a recent statistical mechanical study, that such a molecular system remains ergodic also below the calorimetric glass-transition temperature Tg. Our experimental data give evidence that the time scales of the primary (α) and this secondary relaxations are correlated. Finally a comparison with recent PCS experiments in a colloidal system confirms the primary role of the dynamical crossover in the physics of the dynamical arrest.
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http://dx.doi.org/10.1038/srep03747 | DOI Listing |
Soft Matter
January 2025
Division of Physical Chemistry, Department of Chemistry, Lund University, PO Box 124, SE-221 00 Lund, Sweden.
Attempts to use colloid science concepts to better understand the dynamic properties of concentrated or crowded protein solutions are challenging due to the fact that globular proteins generally have heterogeneous surfaces that result in anisotropic or patchy contributions to their interaction potential. This is particularly difficult when targeting non-equilibrium transitions such as glass and gel formation in concentrated protein solutions. Here we report a systematic study of the reduced zero shear viscosity of the globular protein -crystallin, an eye lens protein that plays a vital role in vision-related phenomena such as cataract formation or presbyopia, and compare the results to the existing structural and dynamic data.
View Article and Find Full Text PDFEcotoxicol Environ Saf
January 2025
Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou 510080, China. Electronic address:
Di(2-ethylhexyl) phthalate (DEHP) is a widespread ubiquitous phthalate environmental contaminant. The male reproductive toxicity (MRT) from exposure to DEHP and its main metabolite, mono(2-ethylhexyl) phthalate (MEHP), has been well documented. Fully elucidating its toxic mechanism and discovering effective antagonists are desirable means to reduce the health risks of DEHP.
View Article and Find Full Text PDFBiol Reprod
January 2025
Laboratory of Animal Genetics and Reproduction, Research Faculty of Agriculture, Hokkaido University, Sapporo 060-8589, Japan.
Unlike differentiated somatic cells, which possess elongated mitochondria, undifferentiated cells, such as those of preimplantation embryos, possess round, immature mitochondria. Mitochondrial morphology changes dynamically during cell differentiation in a process called mitochondrial maturation. The significance of the alignment between cell differentiation and mitochondrial maturity in preimplantation development remains unclear.
View Article and Find Full Text PDFRev Med Suisse
January 2025
Service des urgences, Département des centres interdisciplinaires, Centre hospitalier universitaire vaudois, 1011 Lausanne.
Emergency medicine plays a crucial vital role as the gateway to the Swiss healthcare system. Although it has not yet been officially recognized with a specialist title, unlike most European countries - emergency medicine in Switzerland is characterized by robust research activity. This scientific article demonstrates a dynamic and rigorous evolution.
View Article and Find Full Text PDFMed Chem
January 2025
Department of Chemistry and Biochemistry, Faculty of Medicine and Pharmacy, Ibn Zohr University, Laayoune 70000, Morocco.
Background: Oxidative stress is strongly linked to neurodegeneration through the activation of c-Abl kinase, which arrests α-synuclein proteolysis by interacting with parkin interacting substrate (PARIS) and aminoacyl tRNA synthetase complex-interacting multifunctional protein 2 (AIMP2). This activation, triggered by ataxia-telangiectasia mutated (ATM) kinase, leads to dopaminergic neuron loss and α-synuclein aggregation, a critical pathophysiological aspect of Parkinson's disease (PD). To halt PD progression, pharmacological inhibition of c-Abl kinase is essential.
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