Controllable direction of liquid jets generated by thermocavitation within a droplet.

A high-velocity fluid stream ejected from an orifice or nozzle is a common mechanism to produce liquid jets in inkjet printers or to produce sprays among other applications. In the present research, we show the generation of liquid jets of controllable direction produced within a sessile water droplet by thermocavitation. The jets are driven by an acoustic shock wave emitted by the collapse of a hemispherical vapor bubble at the liquid-solid/substrate interface. The generated shock wave is reflected at the liquid-air interface due to acoustic impedance mismatch generating multiple reflections inside the droplet. During each reflection, a force is exerted on the interface driving the jets. Depending on the position of the generation of the bubble within the droplet, the mechanical energy of the shock wave is focused on different regions at the liquid-air interface, ejecting cylindrical liquid jets at different angles. The ejected jet angle dependence is explained by a simple ray tracing model of the propagation of the acoustic shock wave inside the droplet

Effects of site dilution on the magnetic properties of geometrically frustrated antiferromagnets

The effect of site dilution by non magnetic impurities on the susceptibility of geometrically frustrated antiferromagnets (kagome and pyrochlore lattices) is discussed in the framework of the Generalized Constant Coupling model, for both classical and quantum Heisenberg spins. For the classical diluted pyrochlore lattice, excellent agreement is found when compared with Monte Carlo data. Results for the quantum case are also presented and discussed.Comment: 5 pages, 3 figure

Critical behavior of 2 and 3 dimensional ferro- and antiferromagnetic spin ice systems in the framework of the Effective Field Renormalization Group technique

In this work we generalize and subsequently apply the Effective Field Renormalization Group technique to the problem of ferro- and antiferromagnetically coupled Ising spins with local anisotropy axes in geometrically frustrated geometries (kagome and pyrochlore lattices). In this framework, we calculate the various ground states of these systems and the corresponding critical points. Excellent agreement is found with exact and Monte Carlo results. The effects of frustration are discussed. As pointed out by other authors, it turns out that the spin ice model can be exactly mapped to the standard Ising model but with effective interactions of the opposite sign to those in the original Hamiltonian. Therefore, the ferromagnetic spin ice is frustrated, and does not order. Antiferromagnetic spin ice (in both 2 and 3 dimensions), is found to undergo a transition to a long range ordered state. The thermal and magnetic critical exponents for this transition are calculated. It is found that the thermal exponent is that of the Ising universality class, whereas the magnetic critical exponent is different, as expected from the fact that the Zeeman term has a different symmetry in these systems. In addition, the recently introduced Generalized Constant Coupling method is also applied to the calculation of the critical points and ground state configurations. Again, a very good agreement is found with both exact, Monte Carlo, and renormalization group calculations for the critical points. Incidentally, we show that the generalized constant coupling approach can be regarded as the lowest order limit of the EFRG technique, in which correlations outside a frustrated unit are neglected, and scaling is substituted by strict equality of the thermodynamic quantities.Comment: 28 pages, 9 figures, RevTeX 4 Some minor changes in the conclussions. One reference adde

<em>Theobroma genus</em>: Exploring the therapeutic potential of <em>T. grandiflorum</em> and <em>T. bicolor</em> in biomedicine

\ua9 2024 The Authors. The Amazon rainforest hosts a plethora of fruit-bearing plants, yet many remain untapped for commercial purposes. Among these, Theobroma genus stands out for its unique characteristics deeply rooted in culinary and traditional medicinal practices, significantly contributing to Amazonian biodiversity and cultural heritage. Particularly, T. cacao, the most renowned species, exhibits versatile applications owing to its health benefits, with distinct groups influencing cocoa quality. Similarly, T. bicolor, thriving in humid regions, has undergone domestication to yield pulp and seeds valuable in food and cosmetic industries. Meanwhile, T. grandiflorum, found across tropical regions of Central and South America, presents unique sensory profiles and fruit characteristics, making it a significant player in Amazonian agriculture. This review primarily aims to offer insights into the therapeutic potential of T. grandiflorum and T. bicolor, with comparisons to T. cacao, revealing a notable increase in publications concerning the physico-chemical and biological properties of these species in recent years. Specifically, the review examines their chemical composition, bioactive compounds, and methodologies for determination, with a focus on biological evaluations encompassing enzymatic, cellular, and animal tests, thereby shedding light on the medicinal properties of these species. Finally, future research perspectives, emphasising the utilisation of waste biomass and further exploration of these invaluable Amazonian resources, have been discussed

Winds in Star Clusters Drive Kolmogorov Turbulence

Intermediate and massive stars drive fast and powerful isotropic winds that interact with the winds of nearby stars in star clusters and the surrounding interstellar medium (ISM). Wind-ISM collisions generate astrospheres around these stars that contain hot $T\sim 10^7$ K gas that adiabatically expands. As individual bubbles expand and collide they become unstable, potentially driving turbulence in star clusters. In this paper we use hydrodynamic simulations to model a densely populated young star cluster within a homogeneous cloud to study stellar wind collisions with the surrounding ISM. We model a mass-segregated cluster of 20 B-type young main sequence stars with masses ranging from 3--17 $M_{\odot}$. We evolve the winds for $\sim$11 kyrs and show that wind-ISM collisions and over-lapping wind-blown bubbles around B-stars mixes the hot gas and ISM material generating Kolmogorov-like turbulence on small scales early in its evolution. We discuss how turbulence driven by stellar winds may impact the subsequent generation of star formation in the clusterComment: 12 pages, 5 figures, Accepted for publication in ApJ

Characterization of bespoke force sensors for tailored applications

Bespoke force sensors made with active polymer composites are inexpensive, thin and flexible, hence popular in wearable electronics, however their wider application is limited due to the lack of literature studying their voltage response related errors. We present the voltage response characterization of bespoke force sensors made with an active polymer composite, silver coated fabric, stainless steel thread and silver epoxy. Characterization of the effects of static and dynamic loading was completed with a mechanical testing machine. Static tests consisted of loading and unloading at 0.01, 0.1, 0.5 and 1 N/s, and drift tests for 120 minutes up to 10 N every 1 N. Dynamic tests consisted of a sinusoidal load of 5 N ± 1 N applied at 0.05, 0.1 and 0.5 Hz for 60 minutes. The force-voltage relationships were modelled using an exponential function. Maximum mean drift error was observed when applying different static loads for 120 minutes each. Drift error is minimal at 5 s (<1%)and at 60 (< 5%) minutes with loads under 1 N. Maximum hysteresis of 18% was observed at a 1 N/s loading rate. The maximum drift error after one hour of dynamic loading was observed at 0.5 Hz and is minimal (-0.00004%). The cost of fabricating these sensors is very low compared with commercially available options. These sensors can be fabricated in any shape and size with the added advantage of being able to set the location of the electronic connections as desired

Modeling the Oxygen K Absorption in the Interstellar Medium: An XMM-Newton View of Sco X-1

We investigate the absorption structure of the oxygen in the interstellar medium by analyzing XMM-Newton observations of the low mass X-ray binary Sco X-1. We use simple models based on the O I atomic cross section from different sources to fit the data and evaluate the impact of the atomic data in the interpretation of astrophysical observations. We show that relatively small differences in the atomic calculations can yield spurious results. We also show that the most complete and accurate set of atomic cross sections successfully reproduce the observed data in the 21 - 24.5 Angstrom wavelength region of the spectrum. Our fits indicate that the absorption is mainly due to neutral gas with an ionization parameter of Epsilon = 10(exp -4) erg/sq cm, and an oxygen column density of N(sub O) approx. = 8-10 x 10(exp 17)/sq cm. Our models are able to reproduce both the K edge and the K(alpha) absorption line from O I, which are the two main features in this region. We find no conclusive evidence for absorption by other than atomic oxygen

Proper motions of the HH1 jet

We describe a new method for determining proper motions of extended objects, and a pipeline developed for the application of this method. We then apply this method to an analysis of four epochs of [S~II] HST images of the HH~1 jet (covering a period of $\sim 20$~yr). We determine the proper motions of the knots along the jet, and make a reconstruction of the past ejection velocity time-variability (assuming ballistic knot motions). This reconstruction shows an "acceleration" of the ejection velocities of the jet knots, with higher velocities at more recent times. This acceleration will result in an eventual merging of the knots in $\sim 450$~yr and at a distance of $\sim 80"$ from the outflow source, close to the present-day position of HH~1.Comment: 12 pages, 8 figure

Decision Support System of Innovative High-Temperature Latent Heat Storage for Waste Heat Recovery in the Energy-Intensive Industry

Reductions in energy consumption, carbon footprint, equipment size, and cost are key objectives for the forthcoming energy-intensive industries roadmaps. In this sense, solutions such as waste heat recovery, which can be replicated into different sectors (e.g., ceramics, concrete, glass, steel, aluminium, pulp, and paper) are highly promoted. In this line, latent heat thermal energy storage (TES) contributes as an innovative technology solution to improve the overall system efficiency by recovering and storing industrial waste heat. To this end, phase-change material (PCM) selection is assisted through a decision-support system (DSS). A simplified tool based on the MATLAB(R) model, based on correlations among the most relevant system parameters, was developed to prove the feasibility of a cross-sectorial approach. The research work conducted a parametric analysis to assess the techno-economic performance of the PCM-TES solution under different working conditions and sectors. Additionally, a multicriteria assessment was performed comparing the tool outputs from metal alloys and inorganic hydrated PCM salts. Overall, the inorganic PCMs presented higher net economic and energy savings (up to 25, 000 euro/yr; 480 MWh/yr), while metal alloys involved promising results, shorter cycles, and competitive economic ratios; its commercial development is still limited

Tidally-induced thermonuclear Supernovae

We discuss the results of 3D simulations of tidal disruptions of white dwarfs by moderate-mass black holes as they may exist in the cores of globular clusters or dwarf galaxies. Our simulations follow self-consistently the hydrodynamic and nuclear evolution from the initial parabolic orbit over the disruption to the build-up of an accretion disk around the black hole. For strong enough encounters (pericentre distances smaller than about 1/3 of the tidal radius) the tidal compression is reversed by a shock and finally results in a thermonuclear explosion. These explosions are not restricted to progenitor masses close to the Chandrasekhar limit, we find exploding examples throughout the whole white dwarf mass range. There is, however, a restriction on the masses of the involved black holes: black holes more massive than $2\times 10^5$ M$_\odot$ swallow a typical 0.6 M$_\odot$ dwarf before their tidal forces can overwhelm the star's self-gravity. Therefore, this mechanism is characteristic for black holes of moderate masses. The material that remains bound to the black hole settles into an accretion disk and produces an X-ray flare close to the Eddington limit of $L_{\rm Edd} \simeq 10^{41} {\rm erg/s} M_{\rm bh}/1000 M$_\odot$), typically lasting for a few months. The combination of a peculiar thermonuclear supernova together with an X-ray flare thus whistle-blows the existence of such moderate-mass black holes. The next generation of wide field space-based instruments should be able to detect such events.Comment: 8 pages, 2 figures, EuroWD0