Three modes of the nonstationary holographic current excitation in a gallium oxide crystal

We report the nonstationary holographic current excitation in a β-Ga2O3 crystal at light wavelength λ=457 nm. The material demonstrates insulating properties and high transparency for a visible light, but this, however, does not prevent the dynamic space-charge grating formation and the holographic current observation for various external electric fields - zero, dc and ac ones. The signal amplitude is measured and analyzed versus the frequency of phase modulation, spatial frequency and electric field value. The main photoelectric parameters such as specific photoconductivity, sensor responsivity and diffusion length of carriers are determined for the blue region of spectrum.

Influence of light wavelength on viability and reproductive function of hens

The article presents the results of influence of monochrome light with different light wavelengths on the hens’ viability and productivity. For this purpose, in the conditions of a modern complex for production of food eggs in a poultry house with an area of 2915 m2, 4 groups of hens of the industrial herd “Hy-Line W-36” were formed, each of which was kept in a separate poultry house similar in area and cage equipment. Each poultry house was equipped with “Big Dutchman” cage batteries, consisting of 1176 cages with an area of 40544 cm2. The differences between the poultry houses applied only to LED lamps. Hens of the 1st group were kept using LED lamps with a peak light wavelength of 458 nm (blue color of the spectrum), the 2nd group – 603 nm (yellow color of the spectrum), the 3rd group – 632 nm (orange color of the spectrum) and 4 groups – 653 nm (red color of the spectrum). Every day, for 34 weeks of the productive period (up to 52 weeks of age), the number of eggs laid by the laying hens of each group was determined. The number of hatched hens (due to death and culling) was also counted daily and the number of livestock was determined. Once a week, the weight of eggs and live weight of laying hens were measured from certain labeled cages. It was found that the reduction of the wavelength of light during the keeping of hens in the cages of multi-tiered batteries affects their viability and reproductive function. The decrease in the peak wavelength from 653 to 632 nm, which was manifested by a change in the color of light from red to orange, was accompanied by a decrease in the preservation by 0.3 %, body weight – by 0.8 %, egg laying on the initial laying – by 3.1 %, egg-laying per average laying hen – by 2.8 % and feed costs – by 0.2 %. The decrease in the peak wavelength to 603 nm, that is the change in the color of light from red and orange to yellow, was accompanied by a decrease in the preservation by 6.4–6.7 %, body weight – by 0.5–1.3 %, egg production by initial laying hen – by 7.1–10.0 %, laying hens on the average laying hen – by 0.4–3.2 % and feed costs – by 2.0–2.1 %. The decrease in the peak wavelength to 458 nm, that is the change in light color from red, orange and yellow to blue, was accompanied by a decrease in the preservation by 3.2–9.9 %, body weight – by 5.2–6.5 %, laying hens per initial laying hen – by 6.4–15.8 %, laying hens per middle laying hen – by 2.9–6.0 % and feed costs – by 1.0–3.1 %.

Thoracic Outlet Syndrome: Fingertip Cannot Replace Forearm Photoplethysmography in the Evaluation of Positional Venous Outflow Impairments

Objective: Fingertip photoplethysmography (PPG) resulting from high-pass filtered raw PPG signal is often used to record arterial pulse changes in patients with suspected thoracic outlet syndrome (TOS). Results from venous (low-pass filtered raw signal) forearm PPG (V-PPG) during the Candlestick-Prayer (Ca + Pra) maneuver were recently classified into four different patterns in patients with suspected TOS, two of which are suggestive of the presence of outflow impairment. We aimed to test the effect of probe position (fingertip vs. forearm) and of red (R) vs. infrared (IR) light wavelength on V-PPG classification and compared pattern classifications with the results of ultrasound (US).Methods: In patients with suspected TOS, we routinely performed US imaging (US + being the presence of a positional compression) and Ca + Pra tests with forearm V-PPGIR. We recruited patients for a Ca + Pra maneuver with the simultaneous fingertip and forearm V-PPGR. The correlation of each V-PPG recording to each of the published pattern profiles was calculated. Each record was classified according to the patterns for which the coefficient of correlation was the highest. Cohen’s kappa test was used to determine the reliability of classification among forearm V-PPGIR, fingertip V-PPGR, and forearm V-PPGR.Results: We obtained 40 measurements from 20 patients (40.2 ± 11.3 years old, 11 males). We found 13 limbs with US + results, while V-PPG suggested the presence of venous outflow impairment in 27 and 20 limbs with forearm V-PPGIR and forearm V-PPGR, respectively. Fingertip V-PPGR provided no patterns suggesting outflow impairment.Conclusion: We found more V-PPG patterns suggesting venous outflow impairment than US + results. Probe position is essential if aiming to perform upper-limb V-PPG during the Ca + Pra maneuver in patients with suspected TOS. V-PPG during the Ca + Pra maneuver is of low cost and easy and provides reliable, recordable, and objective evidence of forearm swelling. It should be performed on the forearm (close to the elbow) with either PPGR or PPGIR but not at the fingertip level.

Simulated Study of High-Sensitivity Gas Sensor with a Metal-PhC Nanocavity via Tamm Plasmon Polaritons

An optical configuration was designed and simulated with a metal-photonic crystal (PhC) nanocavity, which had high sensitivity on gas detection. The simulated results shows that this configuration can generate a strong photonic localization through exciting Tamm plasmon polaritons. The strong photonic localization highly increases the sensitivity of gas detection. Furthermore, this configuration can be tuned to sense gases at different conditions through an adjustment of the detection light wavelength, the period number of photonic crystal and the thickness of the gas cavity. The sensing routes to pressure variations of air were revealed. The simulation results showed that the detection precision of the proposed device for gas pressure could reach 0.0004 atm.

Numerical simulation of a plasmonic lens for laser light focusing

In this paper, the design of a plasmonic lens in gold and silver thin films for focusing the light with radial polarization is presented. Using the finite difference time domain method the optimal parameters of the plasmonic lens design are found. It was shown that the silver plasmonic lens produces a tight focal spot with a full width at half maximum of 0.38 of the incident light wavelength.

Nonstationary holographic currents in a β-Ga2O3 crystal at wavelength λ = 457 nm

We report the excitation of nonstationary holographic currents in a monoclinic gallium oxide crystal. Although the crystal is almost transparent and insulating for a visible light, the dynamic space-charge gratings are recorded and holographic currents are observed for both the diffusion and drift modes. The anisotropy along the [100] and [010] directions is revealed, namely, there is a small difference in the transport parameters and a pronounced polarization dependence of the signal. The crystal’s photoconductivity, responsivity and diffusion length of electrons are estimated for the light wavelength λ = 457 nm.

Design and Implementation of a Semi-Reflective Plate Operating in the Visible and near Infrared Fields, with Reflection Coefficient Robust to the Light Wavelength and Angle of Incidence

This research illustrates the design of a parallel plate reflector operating in the visible and near infrared fields, with a reflection and/or transmission coefficients equal to 50%, and robust to the polarization of the used light and its extinction ratio (PER), in each of the two directions of polarization (perpendicular S and parallel P). Also there is no need for accurate adjustment of the plate so that the angle of incidence is exactly equal to 45°. The research has its various applications in optical measurements laboratories, laser technology laboratories, optical communication laboratories, and photography. One of the most important applications of this plate is ophthalmology devices, which can be used as glasses for people with impaired vision, light measurements in laser laboratories and optical measurements. Purpose of the Research: The need for the use of one semi-reflector plate for all the visible and near infrared fields, instead of using one for each wavelength or light field, which will reduce the number of needed optical pieces used in the optical measurement and laser technology laboratories, because of its wide applications.

Emerging Contaminants: An Overview of Recent Trends for Their Treatment and Management Using Light-Driven Processes

The management of contaminants of emerging concern (CECs) in water bodies is particularly challenging due to the difficulty in detection and their recalcitrant degradation by conventional means. In this review, CECs are characterized to give insights into the potential degradation performance of similar compounds. A two-pronged approach was then proposed for the overall management of CECs. Light-driven oxidation processes, namely photo/Fenton, photocatalysis, photolysis, UV/Ozone were discussed. Advances to overcome current limitations in these light-driven processes were proposed, focusing on recent trends and innovations. Light-based detection methodology was also discussed for the management of CECs. Lastly, a cost–benefit analysis on various light-based processes was conducted to access the suitability for CECs degradation. It was found that the UV/Ozone process might not be suitable due to the complication with pH adjustments and limited light wavelength. It was found that EEO values were in this sequence: UV only > UV/combination > photocatalyst > UV/O3 > UV/Fenton > solar/Fenton. The solar/Fenton process has the least computed EEO < 5 kWh m−3 and great potential for further development. Newer innovations such as solar/catalyst can also be explored with potentially lower EEO values.

Photocatalytic Treatment of An Actual Confectionery Wastewater Using Ag/TiO2/Fe2O3: Optimization of Photocatalytic Reactions Using Surface Response Methodology.

Titanium dioxide (TiO2) photocatalysis is one of the most commonly studied advanced oxidation processes (AOPs) for the mineralization of deleterious and recalcitrant compounds present in wastewater as it is stable, inexpensive, and effective. Out of all, doping with metal and non-metals, and the heterojunction with another semiconductor were proven to be efficient methods in enhancing the degradation of organic pollutants under ultraviolet (UV) and visible light. However, complex degradation processes in the treatment of an actual wastewater are difficult to model and optimize. In the present study, the application of a modified photocatalyst, Ag/TiO2/Fe2O3, for the degradation of an actual confectionery wastewater was investigated. Factorial studies and statistical design of experiments using the Box-Behnken method along with response surface methodology (RSM) were employed to identify the individual and cross-factor effects of independent parameters, including light wavelength (nm), photocatalyst concentration (g/L), initial pH, and initial total organic carbon (TOC) concentration (g/L). The maximum TOC removal at optimum conditions of light wavelength (254 nm), pH (4.68), photocatalyst dosage (480 mg/L), and initial TOC concentration (11,126.5 mg/L) was determined through the numerical optimization method (9.78%) and validated with experimental data (9.42%). Finally, the first-order rate constant with respect to TOC was found to be 0.0005 min−1 with a residual value of 0.998.