Water Dynamics in Composite Aqueous Suspensions of Cellulose Nanocrystals and a Clay Mineral Studied through Magnetic Resonance Relaxometry.

1H spin-lattice relaxation time (T1) measurements were performed to probe the dynamic behavior of water in aqueous suspensions of cellulose nanocrystals (CNCs) and a layered smectite clay mineral with different degrees of concentration. 1H-T1 experiments were carried out over a wide frequency domain, ranging from a few kilohertz to 500 MHz, with the aid of conventional and fast field cycling nuclear magnetic resonance (NMR) techniques. The experimental relaxometry data illustrate differences between the dynamic behavior of bulk water and that confined in the vicinity of CNC-clay surfaces. Clay alone in moderate concentration was found to enforce almost no effect on the water dynamics, whereas introducing CNCs to the system presented a significantly enhanced relaxivity. The modeling of the relaxation dispersions allowed the determination of dynamical processes and variables explaining the dynamic behavior of water in CNC-clay suspensions. It turned out that reorientations mediated by translational displacements are a leading NMR relaxation mechanism for water interacting with the surfaces of CNC-clay particles in the low-frequency domain. In the high-frequency regime, however, the inner-sphere paramagnetic relaxation mechanism dominates, which is caused by the interaction of water protons with dissolved Fe ions.

IL17A Polymorphism Is Not Associated with Human T-Lymphotropic Virus 1-Associated Myelopathy/Tropical Spastic Paraparesis.

The human T-lymphotropic virus 1 (HTLV-1) is the causative agent of HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). The present study investigated the association between the rs2275913 polymorphism in the IL17A gene and the development of HAM/TSP. Peripheral blood samples were collected from 116 patients (29 symptomatic patients with HAM/TSP and 87 asymptomatic) with a positive diagnosis of HTLV-1. The single nucleotide polymorphism genotyping was carried out by real time PCR using TaqMan probes. In addition, serum levels of IL-2, IFN-γ, TNF-α, IL-4, IL-6, IL-10, and IL-17 were measured in 64 infected individuals from the study (47 asymptomatic and 17 HAM/TSP), using cytometric bead array technique. No significant differences were found in genotypic and allelic frequencies between the groups. Analysis of cytokine levels showed highest concentrations of IFN-γ and TNF-α in HAM/TSP patients. The results of the present study, therefore, suggest a lack of association between the rs2275913 polymorphism in the IL17A gene and the presence of HAM/TSP.

Perversions with a twist.

Perversions connecting two helices with symmetric handedness are a common occurrence in nature, for example in tendrils. These defects can be found in our day life decorating ribbon gifts or when plants use tendrils to attach to a support. Perversions arise when clamped elastic filaments coil into a helical shape but have to conserve zero overall twist. We investigate whether other types of perversions exist and if they display different properties. Here we show mathematically and experimentally that a continuous range of different perversions can exist and present different geometries. Experimentally, different perversions were generated using micro electrospun fibres. Our experimental results also confirm that these perversions behave differently upon release and adopt different final configurations. These results also demonstrate that it is possible to control on demand the formation and shape of microfilaments, in particular, of electrospun fibres by using ultraviolet light.

First curl, then wrinkle.

The excellent properties of elastomers are exploited to trigger wrinkling instabilities in curved shells. Micro- and nano-fibres are produced by electrospinning and UV irradiated: each fibre consists of a soft core and a stiff outer half-shell. Upon solvent de-swelling, the fibres curl because the shell and the core have different natural lengths. Wrinkling only starts after the fibre has attained a well-defined helical shape. A simple analytical model is proposed to find the curling curvature and wrinkle wavelength, as well as the transition between the "curling" and "wrinkling" regimes. This new instability resembles that found in the tendrils of climbing plants as they dry and lignify.