A note on the breathing mode of an elastic sphere in Newtonian and complex fluids

Experiments on the acoustic vibrations of elastic nanostructures in fluid media have been used to study the mechanical properties of materials, as well as for mechanical and biological sensing. The medium surrounding the nanostructure is typically modeled as a Newtonian fluid. A recent experiment however suggested that high-frequency longitudinal vibration of bipyramidal nanoparticles could trigger a viscoelastic response in water-glycerol mixtures [M. Pelton et al., "Viscoelastic flows in simple liquids generated by vibrating nanostructures," Phys. Rev. Lett. 111, 244502 (2013)]. Motivated by these experimental studies, we first revisit a classical continuum mechanics problem of the purely radial vibration of an elastic sphere, also called the breathing mode, in a compressible viscous fluid, and then extend our analysis to a viscoelastic medium using the Maxwell fluid model. The effects of fluid compressibility and viscoelasticity are discussed. Although in the case of longitudinal vibration of bipyramidal nanoparticles, the effects of fluid compressibility were shown to be negligible, we demonstrate that it plays a significant role in the breathing mode of an elastic sphere. On the other hand, despite the different vibration modes, the breathing mode of a sphere triggers a viscoelastic response in water-glycerol mixtures similar to that triggered by the longitudinal vibration of bipyramidal nanoparticles. We also comment on the effect of fluid viscoelasticity on the idea of destroying virus particles by acoustic resonance

Quality Evaluation of Parmigiano Reggiano Cheese by a Novel Nanowire Device S3 and Evaluation of the VOCs Profile

Abstract A novel nanowire-based sensor device is presented for the quality evaluation of the Italian Parmigiano Reggiano (PR) cheese. As a Protected Designation of Origin (PDO) trademark product, the cheese should follow stringent manufacturing guidelines and must exhibit the representative aromatic volatile organic compounds (VOCs) biomarkers and sensory profile. Any alteration in these features indicates an adulteration of the product as many low quality and substandard PR cheeses are widely available in the market. Different types of grated cheese samples were analyzed and the VOCs were characterized by evaluating the samples with the portable sensor device S3 and Gas Chromatography–Mass Spectrometry technique. The ability of S3 device to distinguish the cheese quality demonstrates its suitability for monitoring the quality control and authenticity of PR cheese

Effects of nonzero photon momentum in (\gamma,2e) processes

We study the effects of nonzero photon momentum on the triply-differential cross section for (\gamma,2e) processes. Due to the low value of the photon momentum, these effects are weak and manifest only in special kinematical conditions like the back-to-back emission of the electrons with equal energy sharing. Helium and a few light helium-like ions are treated in detail. Quite unexpectedly, the magnitude of these effects is maximal for relatively small photon energies. However, although this effect on the TDCS remains rather small, of the order of a few mbarn eV^{-1} sr^{-2}, it is sufficient to be observed experimentally.Comment: 8 pages, 7 figures, 1 tabl

Transfer ionization and its sensitivity to the ground-state wave function

We present kinematically complete theoretical calculations and experiments for transfer ionization in H$^++$He collisions at 630 keV/u. Experiment and theory are compared on the most detailed level of fully differential cross sections in the momentum space. This allows us to unambiguously identify contributions from the shake-off and two-step-2 mechanisms of the reaction. It is shown that the simultaneous electron transfer and ionization is highly sensitive to the quality of a trial initial-state wave function

Static field limit of excitation probabilities in laser-atom interactions

We consider the interaction of atomic hydrogen, in its ground state, with an electromagnetic pulse whose duration is fixed in terms of the number of optical cycles. We study the probability of excitation of the atom in the static field limit i.e. for field frequencies going to zero. Despite the fact that the well-known Born–Fock adiabatic theorem is valid only for a system whose energy spectrum is discrete, we show that it is still possible to use this theorem to derive, in the low frequency limit, an analytical formula which gives the probability of transition to any excited state of the atom as a function of the field intensity, the carrier envelope phase and the number of optical cycles within the pulse. The results for the probability of excitation to lowlying excited states, obtained with this formula, agree with those we get by solving the timedependent Schrödinger equation. The domain of validity is discussed in detail

Practical aspects of initiation and use of SGLT2 inhibitors: inpatient and outpatient perspectives

In today`s therapy of type 2 diabetes mellitus, SGLT2 inhibitors have taken their rightful place both due to their positive hypoglycemic and outstanding cardiorenometabolic effects. Recent randomized clinical trials, such as DAPA HF, EMPEROR-Reduced and EMPEROR-Preserved, show the benefits of their use in the treatment of patients with chronic heart failure without regard to the status of type 2 diabetes mellitus and so significantly expands the range of use of SGLT2 in the practice of doctors of various specialties. This review presents not only the results of the most significant studies of SGLT2 inhibitors, but also the main approaches to the starting therapy with this class of drugs in various clinical situations, both inpatient and outpatient. In addition, potential adverse events and limitations associated with the use of SGLT2 inhibitors are discussed in detail, which must be taken into account when prescribing in particular patient. The practical aspects of SGLT2 inhibitors` prescription are considered separately through the prism of their safe use in the perioperative and postinfarction periods, as well as during other special conditions. Particular attention is paid to the monitoring of physical and general examination data and laboratory instrumental tests, the consideration of which will minimize adverse events and best benefit for many cardiological, endocrinological and nephrological patients