Some remarks on the chemical potential of a system in an external field

The chemical potential change provides a criterion for predicting the spontaneity of any physical and chemical process. If asked to calculate the chemical potential change of a system in which several forces vary, a student might find the task quite complicate at first glance. However, the chemical potential is a state function. This property permits a precise definition of the contribution of each force to the chemical potential when all other relevant parameters are kept constant. The total chemical potential change can easily be calculated by summing up the above contributions. After a brief review of the role played by some parameters of the system, like activity (a) of the components, temperature (T), pressure (p) and surface tension (gamma), as well as of external fields, i.e. gravitational (Mgh), centrifugal (Mcp) and electric field (Fz(i) Phi), an equation for the computation of the chemical potential (mu) including all the above contributes is reported:-, where refers not only to p = p degrees = 1 bar but also to a chosen value of T, h, rho, Phi and r. Finally, applicative examples are illustrated.The chemical potential change provides a criterion for predicting the spontaneity of any physical and chemical process. If asked to calculate the chemical potential change of a system in which several forces vary, a student might find the task quite complicate at first glance. However, the chemical potential is a state function. This property permits a precise definition of the contribution of each force to the chemical potential when all other relevant parameters are kept constant. The total chemical potential change can easily be calculated by summing up the above contributions. After a brief review of the role played by some parameters of the system, like activity ( of the components, temperature (T), pressure (p) and surface tension (), as well as of external fields, i.e. gravitational (ℎ, centrifugal () and electric field (Φ), an equation for the computation of the chemical potential (µ) including all the above contributes is reported: °′ ° ° ℎ Φ 2 , where ° refers not only to p = p° =1 bar but also to a chosen value of T, h, ρ, Φ and r. Finally, applicative examples are illustrated

Semiempirical model for assessing dewatering process by flocculation of dredged sludge in an artificial reservoir

Understanding sedimentation behaviour of clay material is crucial in planning project for sediment removal from bottom of a reservoir. The sedimentation of samples taken from Occhito reservoir ( Italy) is investigated. Samples containing and not containing polyacrylamide have been monitored. Results reveal that polymer induces bridging flocculation and the particle-size distribution tends to become uniform. The sedimentation profiles follow a mater curve. Such experimental observation is used to develop a semi-empirical model for assessment of dewatering process by flocculation of dredged sludge in artificial reservoir. A two-step stage model for assessing the volume of solids in a geotextile tube is suggested. Such model is based on the idea that for very long dewatering times solids reach the configuration of free sedimentation

Could nearby star-forming galaxies light up the point-like neutrino sky?

Star-forming and starburst galaxies, which are well-known cosmic-rays reservoirs, are expected to emit gamma-rays and neutrinos predominantly via hadronic collisions. In this Letter, we analyze the 10-year Fermi-LAT spectral energy distributions of 13 nearby galaxies by means of a physical model which accounts for high-energy proton transport in starburst nuclei and includes the contribution of primary and secondary electrons. In particular, we test the hypothesis that the observed gamma-ray fluxes are mostly due to star-forming activity, in agreement with the available star formation rates coming from IR and UV observations. Through this observation-based approach, we determine the most-likely neutrino counterpart from star-forming and starburst galaxies and quantitatively assess the ability of current and upcoming neutrino telescopes to detect them as point-like sources. Remarkably, we find that the cores of the Small Magellanic Cloud and the Circinus galaxy are potentially observable by KM3NeT/ARCA with 6 years of observation. Moreover, most of the nearby galaxies are likely to be just a factor of a few below the KM3NeT and IceCube-Gen2 point-like sensitivities. After investigating the prospects for detection of gamma-rays above TeV energies from these sources, we conclude that the joint observations of high-energy neutrinos and gamma-rays with upcoming telescopes will be an objective test for our emission model and may provide compelling evidence of star-forming activity as a tracer of neutrino production.Comment: 7 pages, 2 figure

Electrical transport properties of microcrystalline silicon grown by PECVD

The dark conductivity and Hall mobility of hydrogenated silicon films deposited varying the silane concentration f=SiH4/(SiH4+H2) in a conventional plasma enhanced chemical vapor deposition system have been investigated as a function of temperature, taking into account their structural properties. The electrical properties have been studied in terms of a structural two-phase model. A clear transition from the electrical transport governed by a crystalline phase, in the range 1%3%, has been evidenced. Some metastable effects of the dark conductivity have been noticed

Poly(Lactic-co-glycolic) Acid and Phospholipids Hybrid Nanoparticles for Regeneration of Biological Tissue

In tissue regeneration, biomaterials facilitate biological processes. However, a treatment with biomaterials will be successful only if supported by simple and inexpensive technologies which stimulate the regenerative processes. The present study focused on the possibility of creating formulations from which then to obtain suitable materials for the regeneration of heart tissue. The experimental procedure for precipitation of polymer- nanoparticles was modified ad hoc to obtain hybrid poly lactic-co-glycolic acid (PLGA)-phospholipid nanoparticles. The properties of the formulations produced by direct PLGA-phospholipid co-precipitation depend on the mass ratio R= polymer mass/phospholipid mass. The value of this parameter allows us to modulate the properties of the formulations. Formulations with R = 1.5, 2.3, 4, and 9 were prepared, and for each of them the particle-size distribution obtained by dynamic light scattering was studied. All samples showed that the hydrodynamic diameter decreases with increasing R value. This behavior is interpreted as polymer coil shrinkage due to contacts with the non-solvent. The spreadability and ease of obtaining thin sheets were evaluated for each formulation. The formulation with R=4 resulted in a homogeneous and easily workable material in thin sheets

A New In Vivo Model System to Assess the Toxicity of Semiconductor Nanocrystals

In the emerging area of nanotechnology, a key issue is related to the potential impacts of the novel nanomaterials on the environment and human health, so that this technology can be used with minimal risk. Specifically designed to combine on a single structure multipurpose tags and properties, smart nanomaterials need a comprehensive characterization of both chemicophysical properties and adequate toxicological evaluation, which is a challenging endeavour; the in vitro toxicity assays that are often employed for nanotoxicity assessments do not accurately predict in vivo response. To overcome these limitations and to evaluate toxicity characteristics of cadmium telluride quantum dots in relation to surface coatings, we have employed the freshwater polyp Hydra vulgaris as a model system. We assessed in vivo acute and sublethal toxicity by scoring for alteration of morphological traits, population growth rates, and influence on the regenerative capabilities providing new investigation clues for nanotoxicology purposes

Starburst galaxies strike back: a multi-messenger analysis with Fermi-LAT and IceCube data

Starburst galaxies, which are known as "reservoirs" of high-energy cosmic-rays, can represent an important high-energy neutrino "factory" contributing to the diffuse neutrino flux observed by IceCube. In this paper, we revisit the constraints affecting the neutrino and gamma-ray hadronuclear emissions from this class of astrophysical objects. In particular, we go beyond the standard prototype-based approach leading to a simple power-law neutrino flux, and investigate a more realistic model based on a data-driven blending of spectral indexes, thereby capturing the observed changes in the properties of individual emitters. We then perform a multi-messenger analysis considering the extragalactic gamma-ray background (EGB) measured by Fermi-LAT and different IceCube data samples: the 7.5-year High-Energy Starting Events (HESE) and the 6-year high-energy cascade data. Along with starburst galaxies, we take into account the contributions from blazars and radio galaxies as well as the secondary gamma-rays from electromagnetic cascades. Remarkably, we find that, differently from the highly-constrained prototype scenario, the spectral index blending allows starburst galaxies to account for up to $40\%$ of the HESE events at $95.4\%$ CL, while satisfying the limit on the non-blazar EGB component. Moreover, values of $\mathcal{O}(100~\mathrm{PeV})$ for the maximal energy of accelerated cosmic-rays by supernovae remnants inside the starburst are disfavoured in our scenario. In broad terms, our analysis points out that a better modeling of astrophysical sources could alleviate the tension between neutrino and gamma-ray data interpretation.Comment: 20 pages, 15 figures. v2: updated to published versio

Corneal epithelial wound healing promoted by verbascoside-based liposomal eyedrops

Different liposomal formulations were prepared to identify those capable of forming eyedrops for corneal diseases. Liposomes with neutral or slightly positive surface charge interact very well with the cornea. Then these formulations were loaded with verbascoside to heal a burn of corneal epithelium induced by alkali. The cornea surface affected involved in wound was monitored as a function of time. Experimental results were modeled by balance equation between the rate of healing, due to the flow of phenylpropanoid, and growth of the wound. The results indicate a latency time of only three hours and furthermore the corneal epithelium heals in 48 hours.Thus, the topical administration of verbascoside appears to reduce the action time of cells, as verified by histochemical and immunofluorescence assays

Terahertz thermometry: combining hyperspectral imaging and temperature mapping at terahertz frequencies

The accurate and non-invasive determination of multiple physical parameters, with well-defined spatial resolution, is crucial for applications in manufacturing, chemistry, medicine and biology. Specifically, the ability to simultaneously measure both temperature and spectral signatures is still experimentally unavailable. To this end, we propose a mapping technique for biological systems, which exploits a linear correlation between terahertz wave reflectivity and temperature, and allows to spatially and spectrally resolve thermal distributions. This method is applied to a model biological system in two relevant cases where in one example, nanoplasmonic-induced photothermal effects are imaged gaining new insights into collective heating phenomena. In the second example, we demonstrate a joint thermal-hyperspectral imaging approach to chemically map the presence of a model drug formulation and simultaneously investigate its thermal stability in our biological system. This concept can be easily extended and widely applied to all materials that demonstrate a measurable change in their dielectric properties