Incorporation of aspirin modulates the dynamical and phase behavior of the phospholipid membrane

Effect of aspirin on the microscopic dynamics of a membrane has been investigated using quasielastic neutron scattering and neutron spin echo techniques.

Dynamical and Phase Behavior of a Phospholipid Membrane Altered by an Antimicrobial Peptide at Low Concentration

The mechanism of action of antimicrobial peptides is traditionally attributed to the formation of pores in the lipid cell membranes of pathogens, which requires a substantial peptide to lipid ratio. However, using incoherent neutron scattering, we show that even at a concentration too low for pore formation, an archetypal antimicrobial peptide, melittin, disrupts the regular phase behavior of the microscopic dynamics in a phospholipid membrane, dimyristoylphosphatidylcholine (DMPC). At the same time, another antimicrobial peptide, alamethicin, does not exert a similar effect on the DMPC microscopic dynamics. The melittin-altered lateral motion of DMPC at physiological temperature no longer resembles the fluid-phase behavior characteristic of functional membranes of the living cells. The disruptive effect demonstrated by melittin even at low concentrations reveals a new mechanism of antimicrobial action relevant in more realistic scenarios, when peptide concentration is not as high as would be required for pore formation, which may facilitate treatment with antimicrobial peptides.

A study on reaction kinetics and development of silicide coatings on Nb–1Zr–0.1C alloy by molten salt technique

In this study a molten salt technique has been used to produce silicide coating on Nb–1Zr–0.1C alloy using a NaCl–KCl–NaF–Na₂SiF₆–Si melt.

Low-temperature water dynamics in an aqueous methanol solution

An aqueous methanol solution (x(MeOH) = 0.30) has been studied by quasielastic neutron scattering. The single-particle water dynamics were effectively isolated by employing deuterated methanol. A smooth dynamic transition to a sub-Arrhenius temperature dependence has been observed in the relaxation times. We associate this behavior with the formation of small crystallites in the system. These findings are compared with molecular dynamics simulations and previous nuclear magnetic resonance measurements. We discuss possible dynamic signatures of structuring in the mixture.

What do we know about self-reported fatigue in systemic lupus erythematosus?

Fatigue is one of the most complex and ill understood symptoms of chronic illness often reported as the number one complaint by patients with systemic lupus erythematosus (SLE). This paper aims to provide a comprehensive review of the literature on fatigue in SLE. A pool of 55 relevant articles was retrieved via electronic searches of six databases including MEDLINE, EMBASE, CINAHL, AMED, PsychINFO and PubMed. Fatigue in the studies reviewed was assessed by a range of self-report instruments, the content of which is varied. The results displayed a consensus on the high prevalence of fatigue in SLE, which is significantly higher when compared with controls. The aetiology of fatigue appears to be multifactorial. Disease activity is not always significantly associated with fatigue, in comparison with other secondary features of SLE and psychological variables. The literature is limited by the cross-sectional nature of most of the studies, which does not permit for any firm conclusion regarding the direction of causal relationships to be made. The high prevalence of fatigue in SLE emphasizes the need for further detailed prospective research to inform the understanding of its aetiology, course and management.

Dynamics of biological macromolecules: not a simple slaving by hydration water

We studied the dynamics of hydrated tRNA using neutron and dielectric spectroscopy techniques. A comparison of our results with earlier data reveals that the dynamics of hydrated tRNA is slower and varies more strongly with temperature than the dynamics of hydrated proteins. At the same time, tRNA appears to have faster dynamics than DNA. We demonstrate that a similar difference appears in the dynamics of hydration water for these biomolecules. The results and analysis contradict the traditional view of slaved dynamics, which assumes that the dynamics of biological macromolecules just follows the dynamics of hydration water. Our results demonstrate that the dynamics of biological macromolecules and their hydration water depends strongly on the chemical and three-dimensional structures of the biomolecules. We conclude that the whole concept of slaving dynamics should be reconsidered, and that the mutual influence of biomolecules and their hydration water must be taken into account.

Glass transition and molecular mobility in polymer thin films

Extensive studies on polymer thin films to date have revealed their interesting but unusual properties such as film thickness dependence of glass transition temperature Tg and thermal expansivity. Recent studies have shown that the lower Tg is not always related to the higher mobility in polymer thin films, which contradicts our current understanding of the glass transition process. In this work, we report the results of inelastic neutron-scattering measurements on polystyrene thin films using two spectrometers with different energy resolutions as well as ellipsometry measurements. The results are interpreted in terms of cooperatively rearranging region and motional slowing down due to the surface effect that explain plausibly the anomalous relationship between the glass transition temperature Tg and the molecular mobility in thin films.