A STUDY ON THE RELATION BETWEEN MORPHOLOGICAL AND CHEMICAL CHANGES AND WETTABILITY MODIFICATION OF POLYETHERSULFONE SURFACE AFTER IRRADIATION WITH A PULSED KrF LASER

Laser irradiation is used for surface modification of polymers aiming to improve their properties for different applications. The wettability of a polymeric surface can significantly affect its performance for biological applications. In this paper, the interaction of high-energy KrF laser photons in the two above- and below-threshold regimes with polyethersulfone polymer is studied. The role of morphological and chemical changes of the irradiated polymer and their correlation in the modification of the wetting property of this polymer is investigated. The obtained results show that the morphological parameter of surface roughness is the dominant mechanism in the below-threshold regime, while in the above-threshold region, the competition between this parameter and the carbonization amount of the surface determines the final hydrophilic response.

The interplay between subcritical fluctuations and import: understanding COVID-19 epidemiology dynamics

The effective reproduction ratio r(t) parameter of an epidemic, defined as the average number of secondary infected cases per infectious case in a population in the current state, including both susceptible and non-susceptible hosts, controls the transition between a sub-critical threshold regime (r(t) < 1) and a supercritical threshold regime r(t) > 1). While in sub-critical regimes, an index infected case will cause an outbreak that will die out sooner or later, with large fluctuations observed when approaching the epidemic threshold, the supercritical regimes leads to an exponential growths of infection.The super- or sub-critical regime of an outbreak is often not distinguished when close to the epidemic threshold, but its behaviour is of major importance to understand the course of an epidemic and public health management of disease control. In a sub-critical parameter regime undetected infection, here called “imported case” or import, i.e. a susceptible individual becoming infected from outside the study area e.g., can either spark recurrent isolated outbreaks or keep the ongoing levels of infection, but cannot cause an exponential growths of infection. However, when the community transmission becomes super-critical, any index case or few “imported cases” will lead the epidemic to an exponential growths of infections, hence being distinguished from the sub-critical dynamics by a critical epidemic threshold in which large fluctuations occur in stochastic versions of the considered processes.As a continuation of the COVID-19 Basque Modeling Task Force (BMTF), we now investigate the role of critical fluctuations and import in basic Susceptible-Infected-Susceptible (SIS) and Susceptible-Infected-Recovered (SIR) epidemiological models on disease spreading dynamics. Without loss of generality, these simple models can be treated analytically and, when considering the mean field approximation of more complex underlying stochastic and eventually spatially extended or generalized network processes, results can be applied to more complex models used to describe the COVID-19 epidemics. In this paper, we explore possible features of the course of an epidemic, showing that the sub-critical regime can explain the dynamic behaviour of COVID-19 spreading in the Basque Country, with this theory supported by real data.

Memristor: A Unique Discovery for Reducing Power

A Process parameter variation has increasing, which results unpredictable device behaviour, due to occurrence of deep submicron CMOS technology. As the time passage this issue is exasperated by low power requirements which are approaching transistor operation into sub threshold regime. Principally for portable devices efficient, capable and process variation amiable memory is the most demandable in the market. In designing of low power memories, leakage power is observant parameter to design low power devices, because leakage power plays a dominant role in the total power utilization of the devices. In this paper, simple 6T SRAM formed with memristor has compared with the technique based 6T SRAM for the various parameters like total power and leakage power

Stress-Controlled Frequency Tuning and Parametric Amplification of the Vibrations of Coupled Nanomembranes

Noninvasive tuning of the mechanical resonance frequencies of suspended parallel nanomembranes in various monolithic arrays is achieved by piezoelectric control of their tensile stress. Parametric amplification of their thermal fluctuations is shown to be enhanced by the piezoelectric actuation and amplification factors of up to 20 dB in the sub-parametric oscillation threshold regime are observed.