Major and Minor Contributions to X-ray Characteristic Lines in the Framework of the Boltzmann Transport Equation

The emission of characteristic lines after X-ray excitation is usually explained as the consequence of two independent and consecutive physical processes: the photoelectric ionization produced by incoming photons and the successive spontaneous atomic relaxation. However, the photoelectric effect is not the only ionization mechanism driven by incoming photons. It has been recently shown that Compton ionization is another possible process that contributes not negligibly to the ionization of the L and M shells. In addition, the secondary electrons from these two interactions, photoelectric and Compton, are also able to ionize the atom by means of so-called impact ionization. Such a contribution has been recently described, showing that it can be relevant in cases of monochromatic excitation for certain lines and elements. A third mechanism of line modification is the so-called self-enhancement produced by absorption of the tail of Lorentzian distribution of the characteristic line, which mainly modifies the shape of the lines but also produces an intensity increase. The four effects contribute to the formation of the characteristic line and must be considered to obtain a precise picture in terms of the shell and the element. This work furnishes a review of these contributions and their formal theoretical descriptions. It gives a complete picture of the photon kernel, describing the emission of characteristic X-rays comprising the main photoelectric contribution and the three effects of lower extent. All four contributions to the characteristic X-ray line must be followed along successive photon interactions to describe multiple scattering using the Boltzmann transport equation for photons

Sensible Heat Transfer during Droplet Cooling:Experimental and Numerical Analysis

This study presents the numerical reproduction of the entire surface temperature field resulting from a water droplet spreading on a heated surface, which is compared with experimental data. High-speed infrared thermography of the back side of the surface and high-speed images of the side view of the impinging droplet were used to infer on the solid surface temperature field and on droplet dynamics. Numerical reproduction of the phenomena was performed using OpenFOAM CFD toolbox. An enhanced volume of fluid (VOF) model was further modified for this purpose. The proposed modifications include the coupling of temperature fields between the fluid and the solid regions, to account for transient heat conduction within the solid. The results evidence an extremely good agreement between the temporal evolution of the measured and simulated spreading factors of the considered droplet impacts. The numerical and experimental dimensionless surface temperature profiles within the solid surface and along the droplet radius, were also in good agreement. Most of the differences were within the experimental measurements uncertainty. The numerical results allowed relating the solid surface temperature profiles with the fluid flow. During spreading, liquid recirculation within the rim, leads to the appearance of different regions of heat transfer that can be correlated with the vorticity field within the droplet

Erythrocyte morphology automated analysis: proposal for a new prediction tool of essential hypertension diagnosis

Erythrocyte morphology has already been studied in essential hypertension (EH) and cell membrane alterations have been observed. Relationships among red cell rheological, biochemical, and morphological properties still appear complex and are not clearly understood

Mating activates the heme peroxidase HPX15 in the sperm storage organ to ensure fertility in Anopheles gambiae

Anopheles gambiae mosquitoes are major African vectors of malaria, a disease that kills more than 600,000 people every year. Given the spread of insecticide resistance in natural mosquito populations, alternative vector control strategies aimed at reducing the reproductive success of mosquitoes are being promoted. Unlike many other insects, An. gambiae females mate a single time in their lives and must use sperm stored in the sperm storage organ, the spermatheca, to fertilize a lifetime’s supply of eggs. Maintenance of sperm viability during storage is therefore crucial to the reproductive capacity of these mosquitoes. However, to date, no information is available on the factors and mechanisms ensuring sperm functionality in the spermatheca. Here we identify cellular components and molecular mechanisms used by An. gambiae females to maximize their fertility. Pathways of energy metabolism, cellular transport, and oxidative stress are strongly regulated by mating in the spermatheca. We identify the mating-induced heme peroxidase (HPX) 15 as an important factor in long-term fertility, and demonstrate that its function is required during multiple gonotrophic cycles. We find that HPX15 induction is regulated by sexually transferred 20-hydroxy-ecdysone (20E), a steroid hormone that is produced by the male accessory glands and transferred during copulation, and that expression of this peroxidase is mediated via the 20E nuclear receptor. To our knowledge, our findings provide the first evidence of the mechanisms regulating fertility in Anopheles, and identify HPX15 as a target for vector control

Effect of wettability on nucleate boiling

Papers presented to the 11th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 20-23 July 2015.Heat transfer enhancement at liquid-solid interfaces is often achieved by modifying the surface properties. However, deep efforts to describe the actual role of surface modification only started at the 1980’s and much work has left undone since then. The wettability is a key parameter governing heat, mass and momentum transport at liquid-solid interfaces. However it is usually quantified using macroscopic quantities, which cannot be related with the micro-and-nano-scale phenomena occurring at the interface. In this context, the present paper revises the potential and limitations of using macroscopic apparent contact angles to predict the wetting regimes. Then, these angles are used to relate the wetting regimes with bubble dynamics and heat transfer processes occurring at pool boiling. The results show that the macroscopic angles are useful to establish general trends and differentiate bubble dynamics behaviour occurring for opposite wetting regimes. However, milder wetting changes occurring within each regime, caused, for instance, by surface topography are not well captured by the apparent angle, as the surface topography is not scaled to affect this macroscopic angle, although it can clearly influence the bubble formation and departure mechanisms and, consequently the heat transfer coefficients. In line with this, the concept of the micro-scale contact angle, as introduced by Phan et al. [1] is used here together with a geometrical parameter to include the effect of surface topography, to describe the role of the wettability on bubble dynamics. Based on this analysis, a multi-scale approach is proposed to include the role of wettability on correlations predicting the pool boiling heat transfer coefficients.am201

New Histamine-Related Five-Membered N-Heterocycle Derivatives as Carbonic Anhydrase I Activators

A series of histamine (HST)-related compounds were synthesized and tested for their activating properties on five physiologically relevant human Carbonic Anhydrase (hCA) isoforms (I, II, Va, VII and XIII). The imidazole ring of HST was replaced with different 5-membered heterocycles and the length of the aliphatic chain was varied. For the most interesting compounds some modifications on the terminal amino group were also performed. The most sensitive isoform to activation was hCA I (K(A) values in the low micromolar range), but surprisingly none of the new compounds displayed activity on hCA II. Some derivatives (1, 3a and 22) displayed an interesting selectivity for activating hCA I over hCA II, Va, VII and XIII