جستجوی مقالات مرتبط با کلیدواژه "visible light" در نشریات گروه "پزشکی"

The toxicity of oxytetracycline (OTC) antibiotic remains in the environment and threatens the life of living things. In this research, two series of ZnO nanoparticle catalysts with different particle sizes were prepared.. The structural and optical characteristics of the samples were analyzed and the photocatalytic degradation of OTC was investigated under a 100 W visible light irradiation. The samples prepared using zinc nitrate and zinc acetate showed different photocatalytic performance. The catalysts prepared at lower calcination temperatures show higher photocatalytic performance due to the active surface of the particles. The intensity of the peaks in the XRD patterns of samples also increases with increasing calcination temperature, which confirms the increase in the size of the nanoparticles. The decrease in particle size with increasing calcination temperature was confirmed by FESEM images. On the other hand, the band gap energy was reduced by decreasing the calcination temperature, which increases the performance of the photocatalytic activity. The 27 nm ZnO nanoparticles prepared using zinc nitrate showed 100 % degradation efficiency. As a result, we reached the maximum performance of pure ZnO by only controlling the size and morphology, without making nanocomposite or doping different elements.

As the use of electronic devices such as mobile phones, tablets, and computers continues to rise globally, concerns have been raised about their potential impact on human health. Exposure to high energy visible (HEV) blue light, emitted from digital screens, particularly the so-called artificial light at night (ALAN), has been associated with adverse health effects, ranging from disruption of circadian rhythms to cancer. Breast cancer incidence rates are also increasing worldwide.

This study aimed at finding a correlation between breast cancer and exposure to blue light from mobile phone.

In this retrospective matched case-control study, we aimed to investigate whether exposure to blue light from mobile phone screens is associated with an increased risk of female breast cancer. We interviewed 301 breast cancer patients (cases) and 294 controls using a standard questionnaire and performed multivariate analysis, chi-square, and Fisher’s exact tests for data analysis.

Although heavy users in the case group of our study had a statistically significant higher mean 10-year cumulative exposure to digital screens compared to the control group (7089±14985 vs 4052±12515 hours, respectively, P=0.038), our study did not find a strong relationship between exposure to HEV and development of breast cancer. 

Our findings suggest that heavy exposure to HEV blue light emitted from mobile phone screens at night might constitute a risk factor for promoting the development of breast cancer, but further large-scale cohort studies are warranted.

This present study involves the sonochemical and microwave synthesis of an efficient light harvesting nanocomposite photocatalyst, ZnO/GO embedded with copper nanoparticles. The synthesised nanocomposite was characterised by various spectroscopic methods like XRD, SEM, EDX, FT-IR, UV-DRS and fluorescence analysis. The catalytic activity of the synthesised nanocomposite was tested using an organophosphorous pesticide, as the test solution and its percentage efficiency of degradation were studied. About 99 % of 40 ppm of Quinalphos pesticide could be degraded using ZnO/Cu/GO nanocomposite (3 mg/L) under visible light radiation within20 min at neutral pH. The presence of an intrinsic defects and the fluorescence property of the prepared nanocomposite were also detected. The degradation efficiency was estimated by COD and TOC measurements. The reaction rate followed pseudo - first order kinetics with a rate constant of 0.042 min-1. Furthermore, the composite has demonstrated a reusable feature and was utilised for eight cycles without any change in its activity. These findings has illustrated an ecofriendly, more stable and well organised photocatalytic nanocomposite, which could be preferred much for the treatment of industrial and agricultural waste water containing organic contaminants within a short span of time under irradiation using sunlight.

In this work, hydrothermal technique and precursor materials obtained from the wastes of filtration unit of gas pressure reduction station were used to create ZnO-Fe2O3 nanocomposite. FT-IR, FE-SEM, XRD and TEM analyzes were used to investigate the properties of the produced nanocomposite. XRD analysis showed the structure of ZnO and Fe2O3 without impurities. The crystal size of ZnO-Fe2O3 nanocomposite was determined to be about 53 nm. FE-SEM images showed a nanocomposite pattern with an approximate diameter of 50 nm. Finally, visual decomposition of anionic and cationic dyes under visible light was used to study the photocatalytic activity of ZnO-Fe2O3 nanocomposite. By exposing a metal halide lamp to light and darkness for 60 minutes and 150 minutes, respectively, it was possible to study the photocatalytic activity of the synthesized nanocomposite in removing anionic and cationic dyes from aqueous medium. In the photocatalytic degradation of anionic and cationic dyes, the following factors were considered as essential variables: pH, initial dye concentration, nanocomposite content and exposure time. In this study, the degradation percentage of anionic and cationic dyes of ZnO-Fe2O3 nanocomposite with a ratio of 0.75:1 was 99.89 and 99.9%, respectively. The amount of band gap was calculated by Tack plot method and electrical conductivity was calculated using electrochemical impedance spectroscopy, which reduced the band gap. And the resistance increases. Due to the acceleration of charge transfer at the heterogeneous junction surface and the suppression of electron/hole pairs from recombination, the ZnO-Fe2O3 nanocomposite significantly increased the visible light current response.

Nowadays, there is a growing global concern over rapidly increasing screen time (smartphones, tablets, and computers). An accumulating body of evidence indicates that prolonged exposure to short-wavelength visible light (blue component) emitted from digital screens may cause cancer. The application of machine learning (ML) methods has significantly improved the accuracy of predictions in fields such as cancer susceptibility, recurrence, and survival. 

To develop an ML model for predicting the risk of breast cancer in women via several parameters related to exposure to ionizing and non-ionizing radiation.

In this analytical study, three ML models Random Forest (RF), Support Vector Machine (SVM), and Multi-Layer Perceptron Neural Network (MLPNN) were used to analyze data collected from 603 cases, including 309 breast cancer cases and 294 gender and age-matched controls. Standard face-to-face interviews were performed using a standard questionnaire for data collection. 

The examined models RF, SVM, and MLPNN performed well for correctly classifying cases with breast cancer and the healthy ones (mean sensitivity> 97.2%, mean specificity >96.4%, and average accuracy >97.1%).  

Machine learning models can be used to effectively predict the risk of breast cancer via the history of exposure to ionizing and non-ionizing radiation (including blue light and screen time issues) parameters. The performance of the developed methods is encouraging; nevertheless, further investigation is required to confirm that machine learning techniques can diagnose breast cancer with relatively high accuracies automatically.

Visible light active ZnWO4/ZrO2 nanocomposite was prepared via hydrothermal method. The nanocomposite was characterized by UV-visible diffuse reflectance spectroscopy (UV-vis-DRS), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Scanning Electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and transmission electron microscopy (TEM) techniques. The XRD results showed that average particle size of ZrO2, ZnWO4 and ZnWO4/ZrO2 were found to be 29.20 nm, 23.78 nm and 20.14 nm respectively and the phase structure for ZrO2 and ZnWO4 in the composite was Rhombohedral and Monoclinic respectively. The UV–vis absorption spectra of the ZnWO4/ZrO2 nanocomposite noticeably shifted to the visible light region compared to that of the ZrO2. The prepared photocatalyst were composed of plate and spongy sphere with little agglomeration was seen from SEM result. The photocatalytic activities of the prepared nanocomposite was evaluated for the degradation of methyl orange (MO) under visible light irradiations. The effect of operational parameters such as initial dye concentration, pH, catalyst concentration and irradiation time have been investigated in detail. The photocatalytic degradation efficiency of ZnWO4/ZrO2, ZnWO4 and ZrO2 for 95%, 72% and 60 % respevtively. The high photocatalytic activity can be attributed to stronger absorption in the visible light region, a greater specific surface area, smaller crystal sizes, more surface OH groups, and to the effect of ZnWO4 doping, which resulted in a lower band gap energy.

The solar radiation consists of a vast spectrum of wavelengths such as visible light and ultraviolet radiation (UVR). The amount of UVR that reaches the Earthchr('39')s surface is very important due to its role in vitamin D synthesis and causing skin cancers. The hourly and daily mean values of solar UV type A, B, and visible light radiation were measured for the first time during the year.

The hourly and daily mean values of UVR and visible light intensity of solar radiation at Tabriz were measured and analyzed between the 2017 and 2018 years. The intensity of solar UVA and UVB radiation was measured by Hand-held Lux-UV meter device from sunrise to sunset for one hour.

The results showed that the highest values of UVA and UVB radiation, reaching the Earth were between 12 and 13 o’clock. The maximum and minimum values of UVR were recorded during the months of May and January, respectively. The maximum amounts of UVA and UVB during the whole year were 52.48 and 2.82 W/m2, respectively. Also, the lowest intensity of UVA and UVB radiation during the whole year was 22.19 and 0.79 W/m2, respectively.

Comparison of maximum and minimum UV amounts of type A and B in May was about 2.36 and 3.56 times more than in January. The measurements showed that the intensity of UVA was significantly higher than UVB amounts.

A flexible route for the electrosynthesis of visible light active CdxZn1-xO nanostructures has been proposed. Various nanostructures were prepared by anodic dissolution in 0.1M Me4NCl by using an applied potential of 15V for 30min. The prepared nanostructures were characterized by diffuse reflectance UV-Vis spectroscopy (DRS), Fourier transforms infrared spectrometry (FT-IR), X-Ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that the crystalline structure, morphology, and energy band gap of the products can be finely adjusted only by varying the duty cycle of the anodeswitching. The visible light activity of the obtained nanostructures was investigated using methyl orange as a model organic pollutant. It was found that the proposed method can be used to obtain very effective CdxZn1-xO photocatalysts by fine tuning of the morphology and energy band gap. The prepared photocatalyst retained 80% of its original activity after 5 replicated uses.

Wearing spectacles is the most common approach in correcting the refractive errors worldwide. Due to harmful effects of overexposure to solar ultraviolet radiations, the usage of multi-layer coatings in ophthalmic lenses has recently been increased. These lenses can reduce the reflections and hence increase the transmission of visible light; they can also decrease the transmission of ultraviolet rays. This study aims to compare the transmission of ultraviolet (A and B) and visible rays through coated and uncoated prescriptive ophthalmic plastic lenses. In this study, 39 minus non-photochromic multi-coated white plastic single-vision lenses; 9 similar lenses but without any coatings were assessed by spectral transmittancemeter for evaluation of the transmission of visible and ultraviolet rays. The transmission of visible light was 97.9%±1.07% for coated lenses and 93.5%±0.54% for lenses without coating. Ultraviolet-A transmission was 12.15%±8.02% for coated lenses compared to 66.27%±23.92% in lenses without coating. The transmission of ultraviolet-B rays was 1.21%±0.4% and 23.0%±15.97% for lenses with and without coatings, respectively. The transmission of visible light was significantly higher in multi-coated lenses compared to uncoated samples; whereas the transmissions of ultraviolet rays in multi-coated lenses were significantly lower than uncoated ones. Therefore, it is recommended that, except for particular cases, prescribed lenses be equipped with this multi-layer coating.

To compare the protection of eyes against visible light (VL) and ultraviolet radiation (UVR) by sunglasses available through the Iranian optician trade union (IOTU) shops and those provided by miscellaneous vendors.

Totally، 353 pairs of sunglasses، including 188 pairs from IOTU shops and 165 pairs from miscellaneous vendors were selected based on systematic random sampling. The amount of UVA، UVB and VL transmission of the samples were examined by spectrophotometer. American national standard institute (ANSI) standards were the reference for measuring the UV transmission.

All of the sunglasses from IOTU shops met ANSI standards in transmission of UVA، UVB، while these percentages in miscellaneous vendors were 92. 1% for UVB and 95. 8% for UVA transmission (P<0. 05). Mean of UVB transmission was 0. 78% in IOTU shops and 1. 8% in miscellaneous vendors. These percentages for UVA transmission was 0. 92% and 7. 1% respectively (P≤0. 001). All of the nonstandard sunglasses regarding UVA transmission had graduated tints. 8. 7% of graduated tints and 1. 45% of smoky tints regarding UVB transmission did not meet the ANSI standards.

Although a number of sunglasses presented by miscellaneous vendors were not standard، but in cases that it is not possible to buy expensive sunglasses، it is advisable to use inexpensive ones with non-graduated tints for eye protection against UVR for daily and non-industrial use.