Seismic Analysis on Cylindrical Tanks Subjected to Horizontal Acceleration

The dynamic behaviour of inviscid fluid contained in horizontally accelerated cylindrical tanks is considered. Mechanical equations describing the fluid motion are developed and simplified by use of small amplitude wave approximations, enabling expressions for the different modes of vibrations, sloshing frequencies and the free surface displacements to be obtained. The expression for free surface displacement is formulated in such a way that the time histories of the free surface displacement can be calculated for tanks subjected to real earthquake accelerograms. Comparisons of predicted and finite element analysis of different modes of vibration of the cylindrical tank, sloshing frequencies and free surface displacements of a model cylindrical water tank subjected to sinusoidal acceleration was found to be in close agreement

Selective ion-permeable membranes by insertion of biopores into polymersomes

In nature there are various specific reactions for which highly selective detection or support is required to preserve their bio-specificity or/and functionality. In this respect, mimics of cell membranes and bio-compartments are essential for developing tailored applications in therapeutic diagnostics. Being inspired by nature, we present here biomimetic nanocompartments with ion-selective membrane permeability engineered by insertion of ionomycin into polymersomes with sizes less than 250 nm. As a marker to assess the proper insertion and functionality of ionomycin inside the synthetic membrane, we used a Ca2+-sensitive dye encapsulated inside the polymersome cavity prior to inserting the biopore. The calcium sensitive dye, ionomycin, and Ca2+ did not influence the architecture and the size of polymersomes. Successful ionomycin functionality inside the synthetic membrane with a thickness of 10.7 nm was established by a combination of fluorescence spectroscopy and stopped-flow spectroscopy. Polymersomes equipped with ion selective membranes are ideal candidates for the development of medical applications, such as cellular ion nanosensors or nanoreactors in which ion exchange is required to support in situ reactions

Photon polarization in light-by-light scattering: Finite size effects

We derive a simple expression for the photon helicity and polarization-flip probabilities in arbitrary background fields, in the low-energy regime. Taking the background to model a focused laser beam, we study the impact of pulse shape and collision geometry on the probabilities and on ellipticity signals of vacuum birefringence. We find that models which do not account for pulse duration can overestimate all signals in near head-on collisions by up to an order of magnitude. Taking pulse duration into account, the flip probability becomes relatively insensitive to both angular incidence and the fine details of the pulse structure

Vacuum refractive indices and helicity flip in strong-field QED

Vacuum birefringence is governed by the amplitude for a photon to flip helicity or polarisation state in an external field. Here we calculate the flip and non-flip amplitudes in arbitrary plane wave backgrounds, along with the induced spacetime-dependent refractive indices of the vacuum. We compare the behaviour of the amplitudes in the low energy and high energy regimes, and analyse the impact of pulse shape and energy. We also provide the first lightfront-QED derivation of the coefficients in the Heisenberg-Euler effective action.Comment: Version 2: additional results added, including discussion of vacuum refractive indices, analysis of flip and non-flip ampltidues at high-energy, additional plots, new title. Now 17 pages, 10 figure

Climate change impacts on plant phenology: Grapevine (vitis vinifera) bud break in wintertime in southern italy

The effects of global warming on plants are not limited to the exacerbation of summer stresses; they could also induce dormancy dysfunctions. In January 2020, a bud break was observed in an old poly-varietal vineyard. Meteorological data elaboration of the 1951–2020 period confirmed the general climatic warming of the area and highlighted the particular high temperatures of the last winter. Phenological records appeared to be significantly correlated to wood hydration and starch reserve consumption, demonstrating a systemic response of the plant to the warm conditions. The eight cultivars, identified by single-nucleotide polymorphism (SNP) profiles and ampelographic description, grown in this vineyard showed different behaviors. Among them, the neglected Sprino, Baresana, Bianco Palmento, and Uva Gerusalemme, as well as the interspecific hybrid Seyve Villard 12.375, appeared to be the most interesting. Among the adaptation strategies to climate changes, the cultivar selection should be considered a priority, as it reduces the inputs required for the plant management over the entire life cycle of the vineyard. Hot Mediterranean areas, such as Salento, are a battlefront against the climate change impacts, and, thus, they represent a precious source of biodiversity for viticulture

Silicon Photo-Multiplier radiation hardness tests with a beam controlled neutron source

We report radiation hardness tests performed at the Frascati Neutron Generator on silicon Photo-Multipliers, semiconductor photon detectors built from a square matrix of avalanche photo-diodes on a silicon substrate. Several samples from different manufacturers have been irradiated integrating up to 7x10^10 1-MeV-equivalent neutrons per cm^2. Detector performances have been recorded during the neutron irradiation and a gradual deterioration of their properties was found to happen already after an integrated fluence of the order of 10^8 1-MeV-equivalent neutrons per cm^2.Comment: 7 pages, 6 figures, Submitted to Nucl. Inst. Meth.

Membrane protein channels equipped with a cleavable linker for inducing catalysis inside nanocompartments

Precisely timed initiation of reactions and stability of the catalysts are fundamental in catalysis. We introduce here an efficient closing-opening method for nanocompartments that contain sensitive catalysts and so achieve a controlled and extended catalytic activity. We developed a chemistry-oriented approach for modifying a pore-forming membrane protein which allows for a stimuli-responsive pore opening within the membrane of polymeric nanocompartments. We synthesized a diol-containing linker that selectively binds to the pores, blocking them completely. In the presence of an external stimulus (periodate), the linker is cleaved allowing the diffusion of substrate through the pores to the nanocompartment interior where it sets off the in situ enzymatic reaction. Besides the precise initiation of catalytic activity by opening of the pores, oxidation by periodate guarantees the cleavage of the linker under mild conditions. Accordingly, this kind of responsive nanocompartment lends itself to harboring a large variety of sensitive catalysts such as proteins and enzymes