Polystyrene Particles and Mammalian Cells Motion Behaviour on Different Surfaces

The stochastic motion behaviour of polystyrene particles and  teratocarcinoma cells on plain and functionalised surfaces is investigated and analysed. The solution of 1 x 106 particles/cells per ml concentration is pipetted into a reservoir and images are captured and analysed using an in-house written software. A theoretical model was used to predict the motion and compared to the experimental results. The conditions and limitations to allow particles and cells to move freely in stochastic motion on surface are discussed in this paper. PEG functionalisation of the glass surface was found to improve the particles and cells mobility, on average 26%. Analysis technique proposed in this paper demonstrates that size distribution of different cell line can be determined. The results are presented in light of the potential application of the observed motion on functionalised surfaces for lab-on-a-chip devices, especially for adherent biological cells applications

Localised and delocalised plasmons in metallic nano-voids

Nanostructured metal films comprised of periodically arranged spherical voids are grown by electrochemical deposition through a self-assembled template. Detailed measurements of the angle- and orientation-dependent reflectivity for different sample geometries reveal the spectral dispersion of several different types of surface plasmon modes. The dependence of the energies of both delocalized Bragg and localized Mie plasmons on the void goemetry is presented, along with theoretical models to explain some of these experimental findings. Strong interactions between the different plasmon modes as well as other mixing processes are identified. Understanding such plasmonic crystals allows for the engineering of devices tailored for a wide range of sensing application

All-cause and liver-related mortality risk factors in excessive drinkers: Analysis of data from the UK biobank

Background: High alcohol intake is associated with increased mortality. We aimed to identify factors affecting mortality in people drinking extreme amounts of alcohol. Methods: We obtained information from the UK Biobank on approximately 500,000 participants aged 40–70 years at baseline assessment in 2006–2010. Habitual alcohol intake, lifestyle and physiological data, laboratory test results, and hospital diagnoses and death certificate data (to June 2020) for 5136 men (2.20% of male participants) and 1504 women (0.60%) who reported consuming ≥80 or ≥50 g/day, respectively, were used in survival analysis. Results: Mortality hazard ratios for these excessive drinkers, compared to all other participants, were 2.02 (95% CI 1.89–2.17) for all causes, 1.89 (1.69–2.12) for any cancer, 1.87 (1.61–2.17) for any circulatory disease, and 9.40 (7.00–12.64) for any liver disease. Liver disease diagnosis or abnormal liver function tests predicted not only deaths attributed to liver disease but also those from cancers or circulatory diseases. Mortality among excessive drinkers was also associated with quantitative alcohol intake; diagnosed alcohol dependence, harmful use, or withdrawal syndrome; and current smoking at assessment. Conclusions: People with chronic excessive alcohol intake experience decreased average survival, but there is substantial variation in their mortality, with liver abnormality and alcohol dependence or other alcohol use disorders associated with a worse prognosis. Clinically, patients with these risk factors and high alcohol intake should be considered for early or intensive management. Research can usefully focus on the factors predisposing to dependence or liver abnormality

Gradients and Modulation of K+ Channels Optimize Temporal Accuracy in Networks of Auditory Neurons

Accurate timing of action potentials is required for neurons in auditory brainstem nuclei to encode the frequency and phase of incoming sound stimuli. Many such neurons express “high threshold” Kv3-family channels that are required for firing at high rates (>∼200 Hz). Kv3 channels are expressed in gradients along the medial-lateral tonotopic axis of the nuclei. Numerical simulations of auditory brainstem neurons were used to calculate the input-output relations of ensembles of 1–50 neurons, stimulated at rates between 100–1500 Hz. Individual neurons with different levels of potassium currents differ in their ability to follow specific rates of stimulation but all perform poorly when the stimulus rate is greater than the maximal firing rate of the neurons. The temporal accuracy of the combined synaptic output of an ensemble is, however, enhanced by the presence of gradients in Kv3 channel levels over that measured when neurons express uniform levels of channels. Surprisingly, at high rates of stimulation, temporal accuracy is also enhanced by the occurrence of random spontaneous activity, such as is normally observed in the absence of sound stimulation. For any pattern of stimulation, however, greatest accuracy is observed when, in the presence of spontaneous activity, the levels of potassium conductance in all of the neurons is adjusted to that found in the subset of neurons that respond better than their neighbors. This optimization of response by adjusting the K+ conductance occurs for stimulus patterns containing either single and or multiple frequencies in the phase-locking range. The findings suggest that gradients of channel expression are required for normal auditory processing and that changes in levels of potassium currents across the nuclei, by mechanisms such as protein phosphorylation and rapid changes in channel synthesis, adapt the nuclei to the ongoing auditory environment