Optimization of the Refractive Index of Antireflection Coatings on Monocrystalline Silicon Solar Cells for Photovoltaic Application

In this work, the following materials have been chosen as anti-reflection layer, namely hafnium (HfO2), magnesium fluoride (MgF2), silicon oxynitrides (SiOxNy), silicon oxides (SiOx), silicon nitride (Si3N4) and hydrogenated silicon nitride (SiNx:H). The calculations were made on the basis of values of layer thicknesses and refractive indices that allow the phase and amplitude conditions to be respected and amplitude conditions. Numerical simulations have shown that low reflectivities at the surface of the surface of the plane cell coated with a simple layer, can be obtained. For example, for simple coatings materials based on Si3N4 and HfO2, we obtain a value of reflectivity around 3 and 2 % respectively. The structures with multilayer coatings such as MgF2/SiNx:H/Si, give a reflectivity of around 1 %. Thus, the refraction index of the coating is an important parameter that plays a major parameter that plays a major role in the optical properties of materials. The closer the refractive index is close to the index of the substrate or the layer above the substrate, the higher the reflectivity.

Seasonal Distribution of the Radio Wave Refraction Index over the Territory of Buryatia

The values of the atmospheric refraction index N for ultra-short radio waves for the territory of Buryatia according to the data of meteorological stations were calculated. The monthly average values N contours maps for the central months of the seasons of 2020 were constructed. It is shown the humidity of Lake Baikal and the relief significantly influence N. On average, the values of the refractive index near the lake are 20–30 N-units higher. It is revealed the monthly average N values have maxima in winter and summer with minimums in spring and autumn, with the main maximum occurring in July.

Physical chemical and citotoxic evaluation of highly diluted solutions of Euphorbia tirucalli L. prepared through the fifty milesimal homeopathic method

Background: although Hahnemann described the fifty-milesimal (LM) method in the 6th edition of the Organon of the Medical Art, very little research has been carried out on the physical chemical properties of these homeopathic preparations. Furthermore, there is still no evidence allowing for the correlation between the alleged physical chemical properties and the biological effects of high dilutions. Aims: to evaluate physical chemical characteristics of LM preparations including electrical conductivity, pH and refraction index, and their effect on biological experimental models. Materials and methods: preparations tested for physical chemical analysis were dilutions 1 lm to 10 lm of Euphorbia tirucalli L. prepared from the latex and the juice of the plant. To rule the seasonal characteristics of this plant, 2 different populations were used, one collected in June 2007 and the other in May 2008. Furthermore, the cytotoxic effect of Euphorbia tirucalli 5 lm was tested on human breast cancer cells (MCF7) through MTT assay. Some differences among the two collections were observed. However, any clear correlation could be observed between physical chemical properties and biological activity.

Plane-wave propagation in media with electromagnetic anisotropy

The propagation of electromagnetic waves in a medium with electrical and magnetic anisotropy is a subject that is not usually handled in conventional optics and electromagnetism books. During this work, we try to give a pedagogical approach to the subject, using tools that are accessible to an average physics student. In this article, we obtain the Fresnel relation in a media with electromagnetic anisotropy, which corresponds to a quartic equation in the refraction index, assuming only that the principal axes of the electric and magnetic tensors coincide. Additionally, we find the geometric location related to the different situations the discriminant of the quartic equation provides. In order to illustrate our findings, we determine the refractive index together with the plane wave equations for certain values of the parameters that meet the established conditions. The target readers of the paper are students pursuing physics at the intermediate undergraduate level.

Two Kinds of Vacuum in Casimir Effect

The Casimir effect is one observable of the existence of the vacuum energy, i.e. the existence of vacuum electromagnetic field. The meaning of this word "vacuum" is physical vacuum, not technology vacuum. Then, we say that the change in the vacuum structure enforced by the plates. There are two kinds of vacuum, one is usual vacua or free vacua (outside the plates). Another is the negative energy vacua (inside the plates), and the refraction index less than 1(n<1). That cause a change in the light speed for electromagnetic waves propagating perpendicular to the plates: △c/c1.6×10-60d-4, and d is the plate distance. When d=10-9m(1nm), △c=10-24c. Then, a two-loop QED effect cause the phase and group velocities of an electromagnetic wave to slightly exceed c. Though the difference are very small, that raise interesting matters of principle. The focus of this paper is to improve the understanding of the nature of quantum vacuum. In the past, to say that "vacuum is not empty" was already a criticism and subversion of classical physics. Now it seems doubly strange to say that there is a negative energy vacuum that is "empty"than the normal physical vacuum. But these theories are rigorously justified; Casimir effect can create an environment with refractive index less than 1(n<1) and lead to the appearance of superluminality, which is one of the representations of "quantum superluminality". These advances in basic science will certainly open up new fields of application, In short, it is not the Casimir structure that creates the quantum vacuum, but the structure that makes the quantum vacuum "emerge"in a clever way as a perceptible physical reality. This is truly a scientific achievement.

Total Cross Sections for Electron and Positron Scattering on Molecules: In Search of the Dispersion Relation

More than one hundred years of experimental and theoretical investigations of electron scattering in gases delivered cross-sections in a wide energy range, from few meV to keV. An analogy in optics, characterizing different materials, comes under the name of the dispersion relation, i.e., of the dependence of the refraction index on the light wavelength. The dispersion relation for electron (and positron) scattering was hypothesized in the 1970s, but without clear results. Here, we review experimental, theoretical, and semi-empirical cross-sections for N2, CO2, CH4, and CF4 in search of any hint for such a relation—unfortunately, without satisfactory conclusions.

Equivalence between positive and negative refractive index materials in electrostatic cloaks

We investigate, both theoretically and numerically, the equivalence relationship between the positive and negative refraction index dielectric materials in electrostatic invisibility cloak. We have derived an analytical formula that enables fast calculate the corresponding positive dielectric constant from the negative refraction index material. The numerical results show that the negative refraction index material can be replaced by the positive refractive index materials in the static field cloak. This offers some new viewpoints for designing new sensing systems and devices in physics, colloid science, and engineering applications.

Infrared spectroscopy, chemical composition and physical-chemical characteristics of the essential oil of red aroeira seeds (Schinus terebinthifolius Raddi) and it is antimicrobial and antioxidant activities

The aim of this study was to characterize the essential oil (EO) of red aroeira seeds and to evaluate their antimicrobial and antioxidant activities. The EO was extracted by hydrodistillation in a Clevenger-type device with a yield of 9.83% ± 0.31%; it was characterized by Fourier-transform infrared spectroscopy (FTIR), gas chromatography and mass spectrometry (GC-MS) to determine its physical-chemical characteristics. The EO showed acidity of 0.2814 mg KOH g-1, a 1.4763 ± 0.0014 refraction index and density of 0.9365 ± 0.01656 g cm-3. Through the FTIR, the absorption bands of the EO indicated the presence of the following components: limonene, delta -3-carene, a pinene and myrcene. By GC-MS the major compounds found were 4(10)-thujene (44.97%) α-Pinene (20.42%), o-Cymene (12.76%) and p-Menth-1-en-4-ol, (R)-(-)-(6.74%). Antimicrobial activity was evaluated against Gram-positive and Gram-negative bacteria. In the microdilution method, no inhibiting activity was found in the tested concentrations (serial dilutions from 25.6 to 0.05 μL mL-1) and in the disk diffusion method, inhibition halos were observed only when pure EO was added. Antioxidant activity was evaluated by DPPH (oxidation-reduction reaction) and FRAP (iron ion reduction). In the DPPH, the obtained result was 0.01119 ± 0.0001 μmol g-1 and in FRAP, 13.813 ± 0.02187 μmol g-1, which demonstrates antioxidant activity in the two evaluated methods, indicating the possible application of the essential oil of red aroeira seeds as a natural antioxidant agent.

Resonance refraction and neutrino oscillations

The refraction index and matter potential depend on neutrino energy and this dependence has a resonance character associated to the production of the mediator in the s−channel. For light mediators and light particles of medium (background) the resonance can be realized at energies accessible to laboratory experiments. We study properties of the energy dependence of the potential for different C-asymmetries of background. Interplay of the background potential and the vacuum term leads to (i) bump in the oscillation probability in the resonance region, (ii) dip related to the MSW resonance in the background, (iii) substantial deviation of the effective ∆m2 above the resonance from the low energy value, etc. We considered generation of mixing in the background. Interactions with background shifts the energy of usual MSW resonance and produces new MSW resonances. Searches of the background effects allow us to put bounds on new interactions of neutrinos and properties of the background. We show that explanation of the MiniBooNE excess, as the bump due to resonance refraction, is excluded.