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Biomedical Optics Express Nov 2019We develop a suitable geometrical-optics approach and demonstrate that it is possible to measure the optical density (OD) of bacterial cultures using a light emitting...
We develop a suitable geometrical-optics approach and demonstrate that it is possible to measure the optical density (OD) of bacterial cultures using a light emitting diode (LED)-based photometer. We measure both attenuation and spot-size variation, and we compensate for diffraction and stray-light impairment related to the incoherent source and large detection area. The approach is validated for different concentrations of two bacterial species, and , that present different shapes and clustering organization.
PubMed: 31799033
DOI: 10.1364/BOE.10.005600 -
Atmospheric Chemistry and Physics Sep 2021During the 3 years of the ObseRvations of Aerosols above CLouds and their intEractionS (ORACLES) campaign, the NASA Orion P-3 was equipped with a 2D stereo (2D-S) probe...
During the 3 years of the ObseRvations of Aerosols above CLouds and their intEractionS (ORACLES) campaign, the NASA Orion P-3 was equipped with a 2D stereo (2D-S) probe that imaged particles with maximum dimension () ranging from 10 < < 1280 μm. The 2D-S recorded supermicron-sized aerosol particles (SAPs) outside of clouds within biomass burning plumes during flights over the southeastern Atlantic off Africa's coast. Numerous SAPs with 10 < < 1520 μm were observed in 2017 and 2018 at altitudes between 1230 and 4000 m, 1000 km from the coastline, mostly between 7-11° S. No SAPs were observed in 2016 as flights were conducted further south and further from the coastline. Number concentrations of refractory black carbon (rBC) measured by a single particle soot photometer ranged from 200 to 1200 cm when SAPs were observed. Transmission electron microscopy images of submicron particulates, collected on Holey carbon grid filters, revealed particles with potassium salts, black carbon (BC), and organics. Energy-dispersive X-ray spectroscopy spectra also detected potassium, a tracer for biomass burning. These measurements provided evidence that the submicron particles originated from biomass burning. NOAA Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) 3 d back trajectories show a source in northern Angola for times when large SAPs were observed. Fire Information for Resource Management System (FIRMS) Moderate Resolution Imaging Spectroradiometer (MODIS) 6 active fire maps showed extensive biomass burning at these locations. Given the back trajectories, the high number concentrations of rBC, and the presence of elemental tracers indicative of biomass burning, it is hypothesized that the SAPs imaged by the 2D-S are examples of BC aerosol, ash, or unburned plant material.
PubMed: 34675969
DOI: 10.5194/acp-21-14815-2021 -
Sensors (Basel, Switzerland) Aug 2021The main features of SG-WAS (SkyGlow Wireless Autonomous Sensor), a low-cost device for measuring Night Sky Brightness (NSB), are presented. SG-WAS is based on the...
The main features of SG-WAS (SkyGlow Wireless Autonomous Sensor), a low-cost device for measuring Night Sky Brightness (NSB), are presented. SG-WAS is based on the TSL237 sensor -like the Unihedron Sky Quality Meter (SQM) or the STARS4ALL Telescope Encoder and Sky Sensor (TESS)-, with wireless communication (LoRa, WiFi, or LTE-M) and solar-powered rechargeable batteries. Field tests have been performed on its autonomy, proving that it can go up to 20 days without direct solar irradiance and remain hibernating after that for at least 4 months, returning to operation once re-illuminated. A new approach to the acquisition of average NSB measurements and their instrumental uncertainty (of the order of thousandths of a magnitude) is presented. In addition, the results of a new Sky Integrating Sphere (SIS) method have shown the possibility of performing mass device calibration with uncertainties below 0.02 mag/arcsec2. SG-WAS is the first fully autonomous and wireless low-cost NSB sensor to be used as an independent or networked device in remote locations without any additional infrastructure.
PubMed: 34451029
DOI: 10.3390/s21165590 -
The Science of the Total Environment Jan 2024We propose a simple technique for microplastic detection based on their interaction with a hydrophilic and anionic fluorescent dye 1,3,6,8 pyrene tetrasulfonate (PTSA)....
We propose a simple technique for microplastic detection based on their interaction with a hydrophilic and anionic fluorescent dye 1,3,6,8 pyrene tetrasulfonate (PTSA). Synthetic microfibers derived from surgical face masks (an abundantly generated plastic waste post COVID) were considered as model microplastics. The interactions between microfibers and the dye were studied as a function of physiological parameters (pH, contact time and temperature), external agents, dye dosage and polymer variants. A pocket-sized photometer (by Lovibond Tintometer group) was employed for the detection and further validated using advanced equipment set-ups (fluorescence microscope, Fourier transform infrared spectroscopy and benchtop spectrofluorometer). Risk assessment studies were conducted on Artemia salina as a model organism. As a risk mitigation strategy, dye recovery followed by sunlight mediated degradation were performed. The detection study was performed in real water samples collected from fresh, estuarine and seawater samples spiked with microfibers. As an outcome, an optimized standard operational conditions were determined for the effective detection of synthetic microfibers. The data obtained could have scientific and industrial impact, in particular for experts working in the broad arena of clean water, who are specifically interested in developing cost-effective solutions for effective detection and biomonitoring of emerging pollutants.
Topics: Plastics; Water; Spectrometry, Fluorescence; Water Pollutants, Chemical; Microplastics; Staining and Labeling; Environmental Monitoring
PubMed: 37944615
DOI: 10.1016/j.scitotenv.2023.168144 -
Therapeutic Advances in Ophthalmology 2023Anthropometry facilitates the evaluation of risks associated with reduced macular pigment optical density (MPOD).
BACKGROUND
Anthropometry facilitates the evaluation of risks associated with reduced macular pigment optical density (MPOD).
OBJECTIVES
To investigate the predictors and anthropometric indices associated with MPOD in healthy adult in Arab population.
DESIGN
This is a cross-sectional study.
METHODS
The MPOD was measured at 0.5° from fovea using a heterochromatic flicker photometer. Healthy participants aged between 20 and 40 years were recruited. The study evaluated the following data of the participants: height, weight, body mass index, body fat percentage, basal metabolic rate, visceral fat level, muscle mass, bone mineral content, and percentage of protein and body water. The correlation between MPOD with anthropometrics and demographic data was evaluated using Spearman's correlation test. The differences among genders were investigated using the Mann-Whitney test. The smoking effect on MPOD was analyzed using the Friedman test.
RESULTS
In all, 143 participants were recruited. The median ± interquartile range was calculated for age (23 ± 4 years), visual acuity (0.00 ± 0.00 logMAR), and MPOD (0.41 ± 0.18). The average MPOD was higher in males than in females but it was not statistically significant ( > 0.05); on the other hand, they were statistically significantly different in most of the anthropometric data. A significant relationship was found between MPOD and percentage of body fat, protein, and body water ( = 0.30, < 0.05). The observed median MPOD value was higher in this study than that found in previous studies in white populations, but lower than that found in studies investigating Asian populations.
CONCLUSION
One of the most important risk factors of age-related macular degeneration is associated with a relative absence of macular pigment. This study brought into focus percentage of protein and body water for further studies as well as the well-established links with body fat and obesity. Unknown predictors of MPOD remain uncovered. The study also provided first report on normative values of MPOD for Arab population and confirmed the differences from other ethnicities.
PubMed: 37599800
DOI: 10.1177/25158414231189099 -
Sensors (Basel, Switzerland) Sep 2023This paper analyzes the light-scattering standards currently used for calibration (verification) and systematic research in photo and spectrophotometry tools. The...
This paper analyzes the light-scattering standards currently used for calibration (verification) and systematic research in photo and spectrophotometry tools. The application specificities in studying the diffuse reflected and transmitted light during biomedical CCD photometry are considered. The advantages of a new class of photometers with non-spherical reflectors as ellipsoids of revolution truncated along the focal planes with the internal mirror surface are presented. The ellipsoid first focal plane is combined with the surface of the under-study media, and the second is optically coupled to the CCD image sensor plane. The principles of zone analysis of spatial distribution reproduced in photometric images on a CCD sensor are substantiated. The illuminance levels of photometric image areas in reflected and transmitted light from the thickness of the standard for the wavelength of laser radiation of 650 nm of different power was experimentally investigated. Polynomial dependences were obtained, and regression coefficients of the illuminance of the external and middle rings in photometric images for the reflected and transmitted light on the laser power were determined.
PubMed: 37765756
DOI: 10.3390/s23187700 -
ACS Omega Aug 2023Herein, we present the immobilization of a technical grade β-d-galactosidase on amino-functionalized microtiter plates. Afterward, we transferred the results to a...
Herein, we present the immobilization of a technical grade β-d-galactosidase on amino-functionalized microtiter plates. Afterward, we transferred the results to a resin-based approach. For the covalent binding of the enzyme, an amino-functionalized microtiter plate was prefunctionalized with 1,4-phenylendiisothiocyanate. The cleavage of the substrate 5-bromo-4-chloro-3-indoxyl-β-d-galactopyranoside (X-Gal) produces a deep blue dye, which was quantified in a microtiter plate reader at 595 nm. The maximum reaction rates and the Michaelis-Menten constant were calculated. In addition, the unwanted blue precipitate formed during the experiments could be minimized by optimizing the experiments. When transferring the immobilization method to Rink amide resin, -nitrophenyl-β-d-galactopyranoside was used as the substrate and the measurement was carried out in a photometer at 420 nm.
PubMed: 37546597
DOI: 10.1021/acsomega.3c03279 -
Scientific Reports Oct 2023The problem of sky pollution with artificial light currently affects practically all branches that are related to the broadly understood environment. This is especially...
The problem of sky pollution with artificial light currently affects practically all branches that are related to the broadly understood environment. This is especially true for astronomical observations. This paper presents the results of measurements of the surface brightness of the night sky for the city of Rzeszów and the surrounding area, which were made in 2015, 2018 and 2021 using the photometer Sky Quality Meter (SQM-L). The measurements show that the surface brightness of the night sky in Rzeszów in 2015 was in the range from 19.20 to 18.67 mag/arcsec, in 2018 the value of brightness oscillated in the range from 18.53 to 16.47 mag/arcsec, and in 2021 this value was in the range from 17.13 by 15.11 mag/arcsec. Translating the obtained values on the Bortle scale, we can see an increase in the brightness of the night sky from class VI in 2015 to class IX in 2021. A similar trend applies to neighboring towns, for which an increase in brightness from class IV in 2015 to class VIII in 2021 was also observed. An increase in the surface brightness of the night sky causes a deterioration or even loss of visibility of astronomical objects in the night sky. This is especially true for comets and low-brightness stars. Based on the measurement results, a forecast of the development of light pollution was prepared for the study areas until 2025. This forecast shows that we will still have to deal with an increase in the surface brightness of the night sky. Due to the further projected increase in the brightness of the night sky, it should be expected that observers in small towns will experience changes in the quality of the sky over the coming years, which will undoubtedly make astronomical observations difficult, in particular for faint celestial bodies such as comets.
PubMed: 37816866
DOI: 10.1038/s41598-023-44423-w -
Atmospheric Measurement Techniques 2020The atmospheric products of the Multi-Angle Implementation of Atmospheric Correction (MAIAC) algorithm include column water vapor (CWV) at a 1 km resolution, derived...
The atmospheric products of the Multi-Angle Implementation of Atmospheric Correction (MAIAC) algorithm include column water vapor (CWV) at a 1 km resolution, derived from daily overpasses of NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) instruments aboard the Aqua and Terra satellites. We have recently shown that machine learning using extreme gradient boosting (XGBoost) can improve the estimation of MAIAC aerosol optical depth (AOD). Although MAIAC CWV is generally well validated (Pearson's >0.97 versus CWV from AERONET sun photometers), it has not yet been assessed whether machine-learning approaches can further improve CWV. Using a novel spatiotemporal cross-validation approach to avoid overfitting, our XGBoost model, with nine features derived from land use terms, date, and ancillary variables from the MAIAC retrieval, quantifies and can correct a substantial portion of measurement error relative to collocated measurements at AERONET sites (26.9% and 16.5% decrease in root mean square error (RMSE) for Terra and Aqua datasets, respectively) in the Northeastern USA, 2000-2015. We use machine-learning interpretation tools to illustrate complex patterns of measurement error and describe a positive bias in MAIAC Terra CWV worsening in recent summertime conditions. We validate our predictive model on MAIAC CWV estimates at independent stations from the SuomiNet GPS network where our corrections decrease the RMSE by 19.7% and 9.5% for Terra and Aqua MAIAC CWV. Empirically correcting for measurement error with machine-learning algorithms is a postprocessing opportunity to improve satellite-derived CWV data for Earth science and remote sensing applications.
PubMed: 33193906
DOI: 10.5194/amt-13-4669-2020 -
Sensors (Basel, Switzerland) Oct 2022Ubiquitous computing has enabled the proliferation of low-cost solutions for capturing information about the user's environment or biometric parameters. In this sense,...
Assessment of the Performance of a Portable, Low-Cost and Open-Source Device for Luminance Mapping through a DIY Approach for Massive Application from a Human-Centred Perspective.
Ubiquitous computing has enabled the proliferation of low-cost solutions for capturing information about the user's environment or biometric parameters. In this sense, the do-it-yourself (DIY) approach to build new low-cost systems or verify the correspondence of low-cost systems compared to professional devices allows the spread of application possibilities. Following this trend, the authors aim to present a complete DIY and replicable procedure to evaluate the performance of a low-cost video luminance meter consisting of a Raspberry Pi and a camera module. The method initially consists of designing and developing a LED panel and a light cube that serves as reference illuminance sources. The luminance distribution along the two reference light sources is determined using a Konica Minolta luminance meter. With this approach, it is possible to identify an area for each light source with an almost equal luminance value. By applying a frame that covers part of the panel and shows only the area with nearly homogeneous luminance values and applying the two systems in a dark space in front of the low-cost video luminance meter mounted on a professional reference camera photometer LMK mobile air, it is possible to check the discrepancy in luminance values between the low-cost and professional systems when pointing different homogeneous light sources. In doing so, we primarily consider the peripheral shading effect, better known as the vignetting effect. We then differentiate the correction factor S of the Radiance Pcomb function to better match the luminance values of the low-cost system to the professional device. We also introduce an algorithm to differentiate the S factor depending on the light source. In general, the DIY calibration process described in the paper is time-consuming. However, the subsequent applications in various real-life scenarios allow us to verify the satisfactory performance of the low-cost system in terms of luminance mapping and glare evaluation compared to a professional device.
Topics: Humans; Vision, Ocular; Photometry
PubMed: 36298068
DOI: 10.3390/s22207706