Methyl group dynamics in a confined glass

We present a neutron scattering investigation on methyl group dynamics in glassy toluene confined in mesoporous silicates of different pore sizes. The experimental results have been analysed in terms of a barrier distribution model, such a distribution following from the structural disorder in the glassy state. Confinement results in a strong decreasing of the average rotational barrier in comparison to the bulk state. We have roughly separated the distribution for the confined state in a bulk-like and a surface-like contribution, corresponding to rotors at a distance from the pore wall respectively larger and smaller than the spatial range of the interactions which contribute to the rotational potential for the methyl groups. We have estimated a distance of 7 Amstrong as a lower limit of the interaction range, beyond the typical nearest-neighbour distance between centers-of-mass (4.7 Amstrong).Comment: 5 pages, 3 figures. To be published in European Physical Journal E Direct. Proceedings of the 2nd International Workshop on Dynamics in Confinemen

Drift and Diffusion in Periodically Driven Renewal Processes

We consider the drift and diffusion properties of periodically driven renewal processes. These processes are defined by a periodically time dependent waiting time distribution, which governs the interval between subsequent events. We show that the growth of the cumulants of the number of events is asymptotically periodic and develop a theory which relates these periodic growth coefficients to the waiting time distribution defining the periodic renewal process. The first two coefficients, which are the mean frequency and effective diffusion coefficient of the number of events are considered in greater detail. They may be used to quantify stochastic synchronization.Comment: 29 pages, 6 figures, submitted to Journal of Statistical Physic

Nanoscale patterning of self-assembled monolayer (SAM)-functionalised substrates with single molecule contact printing

Defined arrangements of individual molecules are covalenty connected ("printed") onto SAM-functionalised gold substrates with nanometer resolution. Substrates were initially pre-functionlised by coating with 3,3′-dithiodipropionic acid (DTPA) to form a self-assembled monolayer (SAM), which was characterised by atomic force microscopy (AFM), contact angle goniometry, cyclic voltammetry and surface plasmon resonance (SPR) spectroscopy. Pre-defined "ink" patterns displayed on DNA origami-based single-use carriers ("stamp") were covalently conjugated to the SAM using 1-ethyl-3-(3-dimethylamino-propyl)carbodiimide (EDC) and N-hydroxy-succinimide (NHS). These anchor points were used to create nanometer-precise single-molecule arrays, here with complementary DNA and streptavidin. Sequential steps of the printing process were evaluated by AFM and SPR spectroscopy. It was shown that 30% of the detected arrangements closely match the expected length distribution of designed patterns, whereas another 40% exhibit error within the range of only 1 streptavidin molecule. SPR results indicate that imposing a defined separation between molecular anchor points within the pattern through this printing process enhances the efficiency for association of specific binding partners for systems with high sterical hindrance. This study expands upon earlier findings where geometrical information was conserved by the application of DNA nanostructures, by establishing a generalisable strategy which is universally applicable to nearly any type of prefunctionalised substrate such as metals, plastics, silicates, ITO or 2D materials

Urinary Bladder Innervation Within the Sacral Roots of a Sheep

Managing the urinary bladder after spinal cord injury is of primary importance because neurogenic dysfunction leads to life-threatening complications. Sacral Anterior Root Stimulators that control the bladder have been available for many years, however, these devices cannot sense the fullness of the bladder or detect the onset of reflex voiding. In order to address this fundamental limitation, this paper explores the possibility of recording the neural signals that encode bladder fullness from the sacral roots in sheep using extra-neural books. Stimulation of and recording from six roots (S1, S2 and S3 bilaterally) shows that efferent and afferent pathways seem to be co-located within roots, but also that simultaneous recording from multiple roots may be useful to enhance overall signal quality

Liesegang patterns: Effect of dissociation of the invading electrolyte

The effect of dissociation of the invading electrolyte on the formation of Liesegang bands is investigated. We find, using organic compounds with known dissociation constants, that the spacing coefficient, 1+p, that characterizes the position of the n-th band as x_n ~ (1+p)^n, decreases with increasing dissociation constant, K_d. Theoretical arguments are developed to explain these experimental findings and to calculate explicitly the K_d dependence of 1+p.Comment: RevTex, 8 pages, 3 eps figure