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Author(s):  
Olga Yuryevna Ridzel ◽  
Henryk Kalbe ◽  
Vytautas Astašauskas ◽  
Pavel Kuksa ◽  
Alessandra Bellissimo ◽  
...  

2021 ◽  
Vol 11 (40) ◽  
pp. 117-117
Author(s):  
Ursula Wolf ◽  
Sabine Klein ◽  
Annegret Sandig ◽  
Stephan Baumgartner

Background Several series of experiments from our research group have shown ultraviolet (UV) light transmission of homeopathic preparations to slightly but significantly differ from controls. We now investigated whether visible and near infrared spectroscopy were also useful for exploring properties of homeopathic preparations. Materials and methods Homeopathic preparations of copper sulfate (CuSO4), hypericum and sulfur (S8) were produced in 30 sequential steps of 1:100 dilutions (c-preparations). As controls, succussed potentization medium was used. Transmission of the samples from 190-1100nm was measured 4 times on 5 days with a double beam Shimadzu UV PC 1601 spectrophotometer. To correct for the daily variations of the spectrophotometer, transmission of the samples at each nm was divided by the average transmission of the controls. Median transmissions of the samples were calculated for the ranges of 190-340nm (near and middle UV), 340-640nm (visible light without red), and 640-1100nm (red and near infrared). Differences in the median transmission between potency levels from 6c to 30c were determined using Kruskal-Wallis and Jonckheere-Terpstra tests. Results Differences in transmissions of the various potency levels were more pronounced in the UV range than in the visible or red/near infrared range. The Kruskal-Wallis test revealed significant differences for homeopathic preparations of CuSO4, hypericum and S8 in the UV range (p=0.032, 0.008, 0.009, respectively) and of S8 in the visible range (p=0.026). Jonckheere's test showed a tendency towards ascending medians with ascending potency levels for CuSO4 in the UV range (p=0.080). Significant trends were revealed for hypericum in the visible range (p=0.042, descending medians) and S8 in the UV range (p=0.015, ascending medians). Conclusion UV spectroscopy seemed to be more suitable for investigating homeopathic preparations than visible or near infrared spectroscopy, since differences in transmission were more pronounced in the UV range.


Chemosensors ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 300
Author(s):  
Soumaya Jaballah ◽  
Yazeed Alaskar ◽  
Ibrahim AlShunaifi ◽  
Imed Ghiloufi ◽  
Giovanni Neri ◽  
...  

In this work, the main objective is to enhance the gas sensing capability through investigating the effect of Al and Mg doping on ZnO based sensors. ZnO, Mg1% doped ZnO, Al5% doped ZnO and (Al5%, Mg1%) co-doped ZnO nanoparticles (NPs) were synthesized by a modified sol-gel method. The structural characterization showed the hexagonal crystalline structure of the prepared samples. Morphological characterizations confirmed the nanometric sizes of the NPs (27–57 nm) and elemental composition investigation proved the existence of Al and Mg with low concentrations. The optical characterization showed the high absorbance of the synthesized samples in the UV range. The gas sensing performances of the synthesized samples, prepared in the form of thick films, were investigated. Sensing tests demonstrated the high influence of the Al and Mg on the sensing performances towards H2 and CO gas, respectively. The 5A1MZO-based sensor exhibits high sensitivity and low detection limits to H2 (<2 ppm) and CO (<1 ppm). It showed a response around 70 (at 250 °C) towards 2000 ppm H2 and 2 (at 250 °C) towards CO.


2021 ◽  
Author(s):  
Valery Shalatonin ◽  
Gerald H. Pollack

Abstract We investigated the effects of unipolar magnetic fields (N or S polarity) on the physical properties of deionized water. Long-term experiments revealed significant pole-dependent changes in water absorption in the UV range (180 – 350 nm). In the case of water in open vessels, the order of absorption values was C-N-S. That is, control (C) water absorbed the most, N-pole-influenced water absorbed less, and S pole the least. The differences in absorption between N and S waters were substantial. In the case of closed vessels, the differences in absorption spectra substantially diminished, and the arrangement of the absorption values became C-S-N (highest to lowest). A correlation between UV absorption values and evaporation rates was also found. The relative order of evaporation rates, C-N-S (highest to lowest), was the same as the order of the absorption values, also C-N-S. The differences in UV absorption spectra of the N- and S-treated waters persisted for several months after removing the magnets. Hence, the effects of magnetic fields were long term. The interaction of magnetic fields with water is of interest not only from a physical sciences perspective, but also in the context of the significant applications in medicine and biology.


2021 ◽  
Vol 2 ◽  
Author(s):  
L. Rodríguez-Suné ◽  
J. Trull ◽  
N. Akozbek ◽  
D. de Ceglia ◽  
M. A. Vincenti ◽  
...  

The predominant methods currently used to determine nonlinear optical constants like the nonlinear refractive index n2 or the third order susceptibility χ(3) rely mostly on experimental, open and closed z-scan techniques and beam deflection methods. While these methods work well when the linear absorption is relatively small or negligible, the retrieval process is more complicated for a strongly scattering, dispersive or absorbing medium. The study of optics at the nanoscale in the picosecond or femtosecond laser pulsed regimes demands the development of new theoretical tools, and diverse experimental approaches, to extract and verify both linear and nonlinear optical dispersions exhibited by matter, especially when material constituents are fashioned into nanostructures of arbitrary shape. We present a practical, combined experimental and theoretical approach based on the hydrodynamic model that uses experimental results of harmonic generation conversion efficiencies to retrieve complex, nonlinear dispersion curves, not necessarily only for third order processes. We provide examples for materials that are of special interest to nanophotonics, for example, silicon, gold, and indium tin oxide (ITO), which displays nonlocal effects and a zero-crossing of the real part of the dielectric constant. The results for silicon and gold compare well with analytical predictions of nonlinear dispersion based on the nonlinear oscillator model. Based on our assessment of third harmonic generation conversion efficiencies in silicon, we predict χω(3) and χ3ω(3) are of order 10−17 (m/V)2 in the visible and near IR ranges, with respective peaks of 10−14 (m/V)2 and 10−16 (m/V)2 in the UV range. Similarly, gold’s χω(3) and χ3ω(3) are of order 10−17–10−16 (m/V)2, and predict χω(3)∼10−17(m/V)2 and χ3ω(3)∼10−18(m/V)2 for ITO. These results clearly suggest that judicious exploitation of the nonlinear dispersion of ordinary semiconductors has the potential to transform device physics in spectral regions that extend well into the UV range.


2021 ◽  
Vol 224 (18) ◽  
Author(s):  
Susan D. Finkbeiner ◽  
Adriana D. Briscoe

ABSTRACT In true color vision, animals discriminate between light wavelengths, regardless of intensity, using at least two photoreceptors with different spectral sensitivity peaks. Heliconius butterflies have duplicate UV opsin genes, which encode ultraviolet and violet photoreceptors, respectively. In Heliconius erato, only females express the ultraviolet photoreceptor, suggesting females (but not males) can discriminate between UV wavelengths. We tested the ability of H. erato, and two species lacking the violet receptor, Heliconius melpomene and Eueides isabella, to discriminate between 380 and 390 nm, and between 400 and 436 nm, after being trained to associate each stimulus with a sugar reward. We found that only H. erato females have color vision in the UV range. Across species, both sexes show color vision in the blue range. Models of H. erato color vision suggest that females have an advantage over males in discriminating the inner UV-yellow corollas of Psiguria flowers from their outer orange petals. Moreover, previous models ( McCulloch et al., 2017) suggested that H. erato males have an advantage over females in discriminating Heliconius 3-hydroxykynurenine (3-OHK) yellow wing coloration from non-3-OHK yellow wing coloration found in other heliconiines. These results provide some of the first behavioral evidence for female H. erato UV color discrimination in the context of foraging, lending support to the hypothesis ( Briscoe et al., 2010) that the duplicated UV opsin genes function together in UV color vision. Taken together, the sexually dimorphic visual system of H. erato appears to have been shaped by both sexual selection and sex-specific natural selection.


2021 ◽  
Author(s):  
dongwei zhai ◽  
Emilie herault ◽  
FREDERIC GARET ◽  
Valdas Pasiskevicius ◽  
Fredrik Laurell ◽  
...  

2021 ◽  
Author(s):  
Thibaut Sylvestre

The physics and applications of fiber-based supercontinuum (SC) sources have been a subject of intense interest over the last decade, with a significant impact on both basic science and industry. New uses for SC sources are also constantly emerging due to their unique properties that combine high brightness, multi-octave frequency bandwidth, fiber delivery, and single-mode output. The last few years have seen significant research efforts focused on extending the wavelength coverage of SC sources towards the 2 to 20 μm molecular fingerprint mid-infrared (MIR) region and in the ultraviolet (UV) down to 100 nm, while also improving stability, noise, and coherence, output power and polarization properties. Here we review a selection of recent advances in SC generation in a range of specialty optical fibers including fluoride, chalcogenide, telluride, and silicon-core fibers for the MIR; UV-grade silica fibers, liquid-filled and gas-filled hollow-core fibers for the UV range; and all-normal dispersion fibers for ultra-low nose coherent SC generation.


Author(s):  
Yujun Hou ◽  
Chun Jiang

Since the growth of single layer of Si has emerged, silicene became a potential candidate material to make up the disadvantage of graphene. In this paper, the complex surface conductivity is applied to characterize the properties of silicene and we investigate the optical characterization of silicene-dielectric interfaces from IR to far UV range. The silicene-Si and silicene-Ge interfaces along both parallel and perpendicular polarization directions of electromagnetic field with normal incidence are considered in this work. The optical properties of the silicene-dielectric systems proposed in this paper lay a foundation for the performance of complex silicene-based optoelectronic devices such as sensors, detectors, filters, UV absorbers and so on.


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