The variability of mass concentrations and source apportionment analysis of equivalent black carbon across urban Europe.

This study analyzed the variability of equivalent black carbon (eBC) mass concentrations and their sources in urban Europe to provide insights into the use of eBC as an advanced air quality (AQ) parameter for AQ standards. This study compiled eBC mass concentration datasets covering the period between 2006 and 2022 from 50 measurement stations, including 23 urban background (UB), 18 traffic (TR), 7 suburban (SUB), and 2 regional background (RB) sites. The results highlighted the need for the harmonization of eBC measurements to allow for direct comparisons between eBC mass concentrations measured across urban Europe. The eBC mass concentrations exhibited a decreasing trend as follows: TR > UB > SUB > RB. Furthermore, a clear decreasing trend in eBC concentrations was observed in the UB sites moving from Southern to Northern Europe. The eBC mass concentrations exhibited significant spatiotemporal heterogeneity, including marked differences in eBC mass concentration and variable contributions of pollution sources to bulk eBC between different cities. Seasonal patterns in eBC concentrations were also evident, with higher winter concentrations observed in a large proportion of cities, especially at UB and SUB sites. The contribution of eBC from fossil fuel combustion, mostly traffic (eBCT) was higher than that of residential and commercial sources (eBCRC) in all European sites studied. Nevertheless, eBCRC still had a substantial contribution to total eBC mass concentrations at a majority of the sites. eBC trend analysis revealed decreasing trends for eBCT over the last decade, while eBCRC remained relatively constant or even increased slightly in some cities.

Assessment of Skin Maturity by LED Light at Birth and Its Association With Lung Maturity: Clinical Trial Secondary Outcomes.

BACKGROUND: Clinicians face barriers when assessing lung maturity at birth due to global inequalities. Still, strategies for testing based solely on gestational age to predict the likelihood of respiratory distress syndrome (RDS) do not offer a comprehensive approach to addressing the challenge of uncertain outcomes. We hypothesize that a noninvasive assessment of skin maturity may indicate lung maturity. OBJECTIVE: This study aimed to assess the association between a newborn's skin maturity and RDS occurrence. METHODS: We conducted a case-control nested in a prospective cohort study, a secondary endpoint of a multicenter clinical trial. The study was carried out in 5 Brazilian urban reference centers for highly complex perinatal care. Of 781 newborns from the cohort study, 640 were selected for the case-control analysis. Newborns with RDS formed the case group and newborns without RDS were the controls. All newborns with other diseases exhibiting respiratory manifestations were excluded. Skin maturity was assessed from the newborn's skin over the sole by an optical device that acquired a reflection signal through an LED sensor. The device, previously validated, measured and recorded skin reflectance. Clinical data related to respiratory outcomes were gathered from medical records during the 72-hour follow-up of the newborn, or until discharge or death, whichever occurred first. The main outcome measure was the association between skin reflectance and RDS using univariate and multivariate binary logistic regression. Additionally, we assessed the connection between skin reflectance and factors such as neonatal intensive care unit (NICU) admission and the need for ventilatory support. RESULTS: Out of 604 newborns, 470 (73.4%) were from the RDS group and 170 (26.6%) were from the control group. According to comparisons between the groups, newborns with RDS had a younger gestational age (31.6 vs 39.1 weeks, P<.001) and birth weight (1491 vs 3121 grams, P<.001) than controls. Skin reflectance was associated with RDS (odds ratio [OR] 0.982, 95% CI 0.979-0.985, R2=0.632, P<.001). This relationship remained significant when adjusted by the cofactors antenatal corticosteroid and birth weight (OR 0.994, 95% CI 0.990-0.998, R2=0.843, P<.001). Secondary outcomes also showed differences in skin reflectance. The mean difference was 0.219 (95% CI 0.200-0.238) between newborns that required ventilatory support versus those that did not and 0.223 (95% CI 0.205-0.241) between newborns that required NICU admission versus those that did not. Skin reflectance was associated with ventilatory support (OR 0.996, 95% CI 0.992-0.999, R2=0.814, P=.01) and with NICU admission (OR 0.994, 95% CI 0.990-0.998, R2=0.867, P=.004). CONCLUSIONS: Our findings present a potential marker of lung immaturity at birth using the indirect method of skin assessment. Using the RDS clinical condition and a medical device, this study demonstrated the synchrony between lung and skin maturity. TRIAL REGISTRATION: Registro Brasileiro de Ensaios Clínicos (ReBEC) RBR-3f5bm5; https://tinyurl.com/9fb7zrdb. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): RR2-10.1136/bmjopen-2018-027442.

Physicochemical characterization and heavy metals analysis from industrial discharges in Upper Awash River Basin, Ethiopia.

The recent expansion of industries in Addis Ababa is causing additional environmental pollution through wastewater discharges; this is becoming a critical concern. Addis Ababa is located in the upper Awash River basin, and is the main source of industrial pollutants to the river. In this study, physicochemical parameters, nutrients and heavy metal content of wastewaters released from 16 factories, 6 tanneries, 6 beverages and 4 diverse factories, and the Akaki-Kality central wastewater treatment plant in Addis Ababa, were sampled to assess the level of pollutants. Heavy metals were determined using inductively coupled plasma optical emission spectroscopy (ICP-OES). Analysis of nutrients were conducted using Palintest Photometer. Physicochemical characteristics were measured either in situ using a portable micro meter or in the laboratory. Among the measured physicochemical properties, critical issues were observed with electrical conductivity, total dissolved solids and total hardness. Effluents from all of the tanneries, and a number of other factories, were found at levels higher than the maximum limits of various guideline standards. In addition, samples from two of the tanneries (T1 and T5), two beverage factories (B3 and B6) and the central wastewater treatment plant showed elevated concentrations of PO4 3-, which violated the limit (10 mg/l) set by Environmental Protection Agency of Ethiopia (ETHEPA). The two tanneries (T1 and T5) also contained higher SO4 2- than the guideline limit of 1000 mg/l. On the other hand, only one factory, one brewery (B3), exhibited NO3 - above the standard limit of 20 mg/l. Whereas NH3, NH4 +, Cl-, S2- and NO2 - were within the limits in all of the samples. Severe pollution was found in wastewaters from tanneries, where half of them (T1, T5 and T6) contained Cr beyond the maximum limit of 2000 µg/l. Furthermore, a third of the tanneries (T1 and T5) and a beverage factory (B5) contained Fe, Mn, Zn and Cu, higher than the ETHEPA limits of 10000, 5000, 5000 and 2000 µg/l, respectively. Waste disposal from factories without proper treatment can cause great harm to the local people and the environment. Hence, the results of this study call for regulatory bodies to pay close attention to factories, particularly tanneries, in Addis Ababa in implementing adequate treatments of their wastewater discharges.

Photometric flow injection analysis of As(III) by using a homemade, LED-based flow-cell device and methyl orange reagent.

Inorganic arsenic especially As(III) is considered a carcinogenic substance and its measurement is important in water samples. In this work, an inexpensive flow injection analysis system was designed for the photometric determination of As(III) at low concentrations. For this purpose, a light-emitting diode (LED) based photometer with a miniaturized detector, was fabricated and used as a determination apparatus and methyl orange was used as a detecting reagent. The fabricated photometer employed the LEDs, as a light source and the light detector. The λmax of emission for emitter and detector LEDs were 525 and 625 nm, respectively. Determination of As (III) was based on its inhibition effect on the redox reaction between methyl orange and X2 (Cl2 or Br2). The decolorization of the reaction products in the FIA system was monitored using the homemade flow cell detector. Analytical figures of merit including linear responses ranging from 0.03 to 3.0 mg/l of As(III) (r = 0.994), detection limits of 0.007 mg/l As(III), RSD% of 1.5% (n = 7), low reagent consumption per determination, and sampling throughput of 50 determinations per hour were achieved.

[Aerosol Optical Characteristics with Ground-based Measurements via Sun Photometer and Its Relationship with PM Particle Concentration in Chang'an].

The simultaneous quantitative investigation of aerosol ground observation data and particle concentration data is important for a better understanding of the vertical distribution characteristics of air pollution and formulating reasonable air pollution control measures in Chang'an, Xi'an. CE-318 measurements from October 2018 to April 2021 were systematically analyzed to reveal the seasonal and yearly variations in atmospheric aerosols in Chang'an. Then, the relationship between AOD and particle concentration in different seasons and different pollution degrees was explored. The obtained results were as follows:① the seasonal variation in AOD in Chang'an was determined, whereby autumn (1.02)>winter (1.00)>summer (0.63)>spring (0.47). Distinct monthly and inter-annual differences in AOD were observed, showing that the annual average of AOD in 2019 was higher than that in 2020. ② Obvious seasonal and monthly differences in aerosol main control modes were observed; the dominant mode of aerosols gradually changed from coarse mode to fine mode from spring to winter. The seasonal variation in the main control mode of aerosols in 2019 was similar to that in the whole observation period. The seasonal aerosol Angstrom wavelength index (Angstrom) was evenly distributed in 2020, and aerosol particles existed in coarse mode form. Generally speaking, the aerosol type in Chang'an was mostly mixed aerosol throughout the whole observation period. ③ Significant seasonal variations in the relationship between AOD and Angstrom was shown, in which the air pollution in spring was dominated by coarse mode aerosol particles. The local pollution in summer was caused by coarse and fine mode aerosol particles, and the fine mode particles were dominant when the pollution was obvious. The characteristic distribution of Angstrom in autumn and winter was similar; in case of local pollution, the coarse mode aerosol particles were dominant, and in case of obvious pollution, the fine mode aerosol particles were dominant. ④ The monthly concentration variation trend of PM2.5 and PM10 in Chang'an consistent with the maximum and minimum values appeared in January and summer, respectively. Seasonal variation in the concentration of PM2.5 and PM10 was apparent, with the highest values in winter. ⑤ A positive correlation between AOD and particulate matter concentration in different seasons and pollution levels was obtained during the observation periods, but the correlation coefficient differed. The specific characteristics were as follows:the correlation between AOD and PM2.5 concentration was greater than that with PM10 concentration; the correlation between AOD and particle concentration in autumn and winter was greater than that in spring and summer; and the correlation between AOD and particulate matter concentration was greater in polluted weather. Particle concentration was the most important determinant of AOD change, followed by relative humidity, which was the meteorological factor with the highest interpretation rate of AOD change in Chang'an. This indicates that a higher correlation between AOD and particle concentration would benefit from a reasonable humidity correction of AOD.

Visibility, aerosol optical depth, and low-visibility events in Bangkok during the dry season and associated local weather and synoptic patterns.

Visibility and aerosol optical depth (AOD) characterization, and their relationship with PM10 and local and synoptic meteorology, were studied for January-March in 2014 and 2015 over Bangkok. Visibility degradation intensifies in the dry season as compared to the wet season due to increase in PM10 and unfavorable meteorological conditions. The average visibility is lower in January and February as compared to the other months. Relatively higher AOD in March despite lower PM10 is attributed to the synergetic effect of moderate relative humidity, secondary aerosols, elevated aerosol layer due to summertime convection, and biomass burning. Larger variability in visibility and PM10 in winter months is due to more synoptic weather fluctuations while AOD shows similar variability for all months attributed partly to fires. Higher PM10 and moderate-to-high relative humidity cause lower visibility in the morning while it improves in afternoon as PM10 and relative humidity decrease. AOD is higher in the afternoon as compared to that in the morning and evening as it is less sensitive to diurnal change in aerosols and meteorology at the surface level. Visibility and AOD relationships with PM10 are dependent on relative humidity. Weaker winds lead to lower visibility, higher PM10, and higher AOD irrespective of wind direction. Stronger winds improve visibility and decrease PM10 for all directions while AOD is higher for all directions except eastern and northeastern. The back-trajectory results show that the transport of pollutant and moist air is coupled with the synoptic weather and influence visibility and AOD. Two low-visibility events were investigated. The first event is potentially caused by the combined effect of local emissions and their accumulation due to stagnant weather conditions, secondary aerosols, and forest fires in the nearby regions. The second event can be attributed to the local emission and fires in the nearby area with hygroscopic growth of aerosols due to moist air from the Gulf of Thailand. Based on these findings, some policy implications have also been given.

Extensive characterization of aerosol optical properties and chemical component concentrations: Application of the GRASP/Component approach to long-term AERONET measurements.

A recently developed GRASP/Component approach (GRASP: Generalized Retrieval of Atmosphere and Surface Properties) was applied to AERONET (Aeronet Robotic Network) sun photometer measurements in this study. Unlike traditional aerosol component retrieval, this approach allows the inference of some information about aerosol composition directly from measured radiance, rather than indirectly through the inversion of optical parameters, and has been integrated into the GRASP algorithm. The newly developed GRASP/Component approach was applied to 13 AERONET sites for different aerosol types under the assumption of aerosol internal mixing rules to analyze the characteristics of aerosol components and their distribution patterns. The results indicate that the retrievals can characterize well the spatial and temporal variability of the component concentration for different aerosol types. A reasonable agreement between GRASP BC retrievals and MERRA-2 BC products is found for all different aerosol types. In addition, the relationships between aerosol component content and aerosol optical parameters such as aerosol optical depth (AOD), fine-mode fraction (FMF), absorption Ångström exponent (AAE), scattering Ångström exponent (SAE), and single scattering albedo (SSA) are also analyzed for indirect verifying the reliability of the component retrieval. It was demonstrated the GRASP/Component optical retrievals are in good agreement with AERONET standard products [e.g., correlation coefficient (R) of 0.93-1.0 for AOD, fine-mode AOD (AODF), coarse-mode AOD (AODC) and Ångström exponent (AE); R = ~ 0.8 for absorption AOD (AAOD) and SSA; RMSE (root mean square error) < 0.03 for AOD, AODF, AODC, AAOD and SSA]. Thus, it is demonstrated the GRASP/Component approach can provide aerosol optical products with comparable accuracy as the AERONET standard products from the ground-based sun photometer measurements as well as some additional important inside on aerosol composition.

Effect of light backscattering from anterior segment structures on automated flare meter measurements.

BACKGROUND: To evaluate effect of maximal anterior cortical lens density, iris scatter and anterior chamber depth on laser flare photometry. METHODS: Patients diagnosed with clinical uveitis were enrolled in the study. Clinical flare gradings were recorded upon the Standardization of Uveitis Nomenclature. Aqueous flare was measured with an automated device (Kowa FM-700). Back-scattering from anterior cortical lens and anterior iris surface was calculated from Scheimpflug images. A curvilinear regression model was used to calculate estimated values for each clinical grade. These values were used to split cases in Group I (laser flare photometry lower than estimated) and Group II (laser flare photometry higher than estimated). Mean anterior chamber depth, pupil aperture, maximal anterior cortical lens density and iris scatter values were compared between two groups. A stepwise multiple regression analysis was performed to determine the effect of clinical flare gradings and ocular parameters on aqueous flare measurements. RESULTS: The study included 228 eyes of 114 cases. Scheimpflug images were obtained from 105 eyes. Estimated aqueous flare measurements (in photons/milliseconds) were 4.87, 8.50, 14.81, 25.83, 45.04 and 136.93 for 0, 0.5+, 1+, 1.5+, 2+ and 3+ clinical flare respectively. Group II had higher maximal anterior cortical lens density than Group I (96.6 ± 37.1 vs 77.9 ± 17.1 pixel unit, p = 0.001). The measured aqueous flare was significantly related to clinical flare, maximal anterior cortical lens density and pupil aperture (adjusted R2: 0.480, p < 0.001). CONCLUSION: The back-scattered light from anterior cortical lens could affect laser flare photometry measurements. This effect might be quantified by Scheimpflug imaging.

Colorimetric Phosphate Detection Using Organic DFB Laser Based Absorption Spectroscopy.

A novel compact laser absorption spectrometer is developed for colorimetric detection. We demonstrate the realization of the system as well as example measurements of phosphate in water samples based on the malachite green (MG) method. A phosphate concentration range of 1 mg/L to 31.25 µg/L (which corresponds to a molar concentration range of 10.5 µmol/L to 329 nmol/L) is investigated. This photometer demonstrates the ease of integration of organic distributed feedback (DFB) lasers and their miniaturizability, leading the way toward optofluidic on-chip absorption spectrometers. We constructed an optically pumped organic second-order DFB laser on a transparent substrate, including a transparent encapsulation layer, to have access to both emission directions of the surface-emitting laser. Using the two different surface emission directions of the laser resonator allows monitoring of the emitted light intensity without using additional optical elements. Based on these advances, it is possible to miniaturize the measurement setup of a laser absorption spectrometer and to measure analytes, such as phosphate.

A nanoenzyme linked immunochromatographic sensor for rapid and quantitative detection of SARS-CoV-2 nucleocapsid protein in human blood.

The establishment of a simple, low-cost, high-sensitive and rapid immunoassay for detecting SARS-CoV-2 antigen in human blood is an effective mean of discovering early SARS-CoV-2 infection and controlling the pandemic of COVID-19. Herein, a smartphone based nanozyme linked immunochromatographic sensor (NLICS) for the detection of SARS-CoV-2 nucleocapsid protein (NP) has been developed on demand. The system is integrated by disposable immunochromatography assay (ICA) and optical sensor devices. Immunoreaction and enzyme-catalyzed substrate color reaction were carried out on the chromatographic strip in a device, of which the light signal was read by a photometer through a biosensor channel, and the data was synchronously transmitted via the Bluetooth to the app in-stored smartphone for reporting the result. With a limit of detection (LOD) of 0.026 ng/mL NP, NLICS had the linear detection range (LDR) between 0.05 and 1.6 ng/mL NP, which was more sensitive than conventional ICA. NLICS took 25 min for reporting results. For detection of NP antigen in clinical serum samples from 21 COVID-19 patients and 80 healthy blood donor controls, NLICS and commercial enzyme linked immunosorbent assay (ELISA) had 76.2% or 47.6% positivity, and 100% specificity, respectively (P = 0.057), while a good correlation coefficient (r = 0.99) for quantification of NP between two assays was obtained. In conclusion, the NLICS was a rapid, simple, cheap, sensitive and specific immunochromatographic sensing assay for early diagnosis of SARS-CoV-2 infection.

SG-WAS: A New Wireless Autonomous Night Sky Brightness Sensor.

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.

[Specular microscopy findings in active uveitis]. / Résultats de la microscopie spéculaire au cours des uvéites actives.

PURPOSE: To study the effect of ocular inflammation in active uveitis on the corneal endothelium. MATERIALS AND METHODS: This is a prospective cross-sectional study involving 63 eyes of 38 patients with active newly-diagnosed uveitis. Eighty-four eyes of 42 non-uveitic subjects served as a control group. All patients underwent detailed ophthalmic examination, laser flare photometry, and non-contact specular microscopy. Eyes with uveitis had a follow-up visit at one month after initiation of treatment, including laser flare photometry and specular microscopy. RESULTS: The mean age of the active uveitis patients was 33 (range: 9-67 years) with 21 men (55%) and 17 women (45%). For the uveitis patients at baseline, the mean flare value was 32ph/ms (range: 15-100ph/ms) with flare photometry value ≥50ph/ms in 13 eyes (21%) and<50ph/ms in 50 eyes (79%). At baseline, cell density (CD) of the uveitis patients was similar to CD in control eyes (p꞊0.16). The percent of hexagonality was significantly lower (p<0.0001), and the coefficient of variance (CV) (p<0.0001) and central corneal thickness (CCT) (p<0.0001) were significantly higher than in the control group. After one month, there was a significant decrease in flare photometry values (p<0.0001), with a mean flare value of 14.5ph/ms (range: 4-60ph/ms). In the active uveitis group, the overall results of specular microscopy did not significantly vary between the initial examination and the 1-month examination. For eyes with flare photometry value ≥50ph/ms at baseline, CD and hexagonal cell count significantly increased on the 1-month examination (p꞊0.01 and p꞊0.02 respectively), while CV and CCT decreased significantly at the one-month follow-up visit (p꞊0.007/p꞊0.03 respectively). For eyes with flare photometry value at baseline <50ph/ms, there was no significant differences in specular microscopy results between the initial examination and the 1-month examination. CONCLUSIONS: In eyes with newly-diagnosed uveitis and active anterior chamber inflammation, specular microscopy shows transient qualitative abnormalities of the corneal endothelium that depend on the severity of the anterior chamber inflammation as measured by the laser flare meter.

[Temporal and Spatial Distribution Characteristics of Aerosol Optical Properties in Urban Agglomerations on the North Slope of the Tianshan Mountains].

In order to explore the temporal and spatial distribution characteristics of atmospheric aerosol optical depth (AOD) in the urban agglomeration on the northern slope of the Tianshan Mountains, the temporal and spatial distribution characteristics and trends of changes in the AOD in the study area from 2000 to 2019 were analyzed by MODIS aerosol products(MCD19-A2). For 2016-2019, when the AOD was relatively stable, the parameters such as the AOD and Ångström wavelength index (α) were analyzed using multi-band sun photometer ground-based remote sensing technology. The results showed that ① the spatial distribution of AOD in the study area was consistent with the topography, and high values were mainly distributed in the low altitude area. The spatial distribution of AOD in the four seasons showed a strong seasonal change from spring (0.15±0.03) > autumn (0.14±0.03) > summer (0.14±0.02). ② In terms of time, the annual average AOD value of the study area was 0.12 from 2000 to 2019 with an annual growth rate of 1.03%, thereby showing an overall increasing trend. The annual variation in the monthly mean value of AOD was bimodal; the first and second peaks were in May and November. The main reason for the increase in AOD was the release and transmission of dust from natural sources and heating. ③ Under the influence of dust weather, the AOD changed sharply in spring, and the size and change range of aerosol particles were larger than those in summer. The high value of AOD in the study area was mainly affected by coarse mode particles. The moisture absorption growth of fine mode particles caused a fluctuation in the AOD, but it was not the cause of the high value of AOD.

Low-Cost Clamp-On Photometers (ClampOD) and Tube Photometers (TubeOD) for Online Cell Density Determination.

Optical density (OD) measurement is the gold standard to estimate microbial cell density in aqueous systems. Recording microbial growth curves is essential to assess substrate utilization, gauge sensitivity to inhibitors or toxins, or determine the perfect sampling point. Manual sampling for cuvette-photometer-based measurements can cause disturbances and impact growth, especially for strictly anaerobic or thermophilic microbes. For slow growing microbes, manual sampling can cause data gaps that complicate analysis. Online OD measurement systems provide a solution, but are often expensive and ill-suited for applications such as monitoring microbial growth in custom or larger anaerobic vessels. Furthermore, growth measurements of thermophilic cultures are limited by the heat sensitivity of complex electronics. Here, we present two simple, low-cost, self-assembled photometers-a "TubeOD" for online measurement of anaerobic and thermophilic cultures in Hungate tubes and a "ClampOD" that can be attached to virtually any transparent growth vessel. Both OD-meters can be calibrated in minutes. We detail the manufacturing and calibration procedure and demonstrate continuous acquisition of high quality cell density data of a variety of microbes, including strict anaerobes, a thermophile, and gas-utilizing strains in various glassware. When calibrated and operated within their detection limits (ca. 0.3-90% of the photosensor voltage range), these self-build OD-meters can be used for continuous measurement of microbial growth in a variety of applications, thereby, simplifying and enhancing everyday lab operations.

Aerosol properties in the atmosphere of Natal/Brazil measured by an AERONET Sun-photometer.

We analyzed data measured by a Sun-photometer of the RIMA-AERONET network with the purpose to characterize the aerosol properties in the atmosphere over Natal, state capital of Rio Grande do Norte, at the coast of Northeast Brazil. Aerosol Optical Depth, Ångström Exponent, Volume Size Distribution, Single Scattering Albedo, Complex Refractive Index, Asymmetry Factor, and Precipitable Water were analyzed from August 2017 to March 2018. In addition, MODIS and CALIOP observations, local Lidar measurements, and modeled backward trajectories were analyzed in a case study on February 9, 2018, that consistently confirmed the identification of a persistent aerosol layer below 4 km agl. Aerosols present in the atmosphere of Natal showed monthly mean Aerosol Optical Depth at 500 nm below 0.15 (~ 75%), monthly means of the Ångström Exponent at 440-670 nm between 0.30 and 0.70 (~ 69%), bimodal Volume Size Distribution is dominantly coarse mode, Single Scattering Albedo at 440 nm is 0.80, Refractive Index - Real Part around 1.50, Refractive Index - Imaginary Part ranging from 0.01 to 0.04, and the Asymmetry Factor ranged from 0.73 to 0.80. The aerosol typing during the measurement period showed that atmospheric aerosol over Natal is mostly composed of mixed aerosol (58.10%), marine aerosol (34.80%), mineral dust (6.30%), and biomass burning aerosols (0.80%). Backward trajectories identified that 51% of the analyzed air masses over Natal originated from the African continent.

[Aerosol Optical Properties over the Ebinur Region].

The key to understanding the transport and deposition process of salt dust to Ebinur Lake involves the quantitative evaluation of the aerosol concentration and characteristics in Jinghe County. Based on the data of the CE-318 sun photometer station in Jinghe County during 2019, the characteristics of the aerosol optical depth (AOD) and Angström exponent (α) were analysed. The results showed that the daily variation of the AOD in Jinghe County was a single peak curve that increased or decreased monotonously in the early/late peak period and peaked at 12:00-14:00, which was opposite to the trend of the α. There were obvious seasonal differences in the aerosol concentration and dominant mode. The seasonal AOD was ranked as:spring (0.403±0.282) > summer (0.222±0.135) > autumn (0.218±0.112), whereas α was ranked as:summer (1.339±0.446) > autumn (1.116±0.278) > spring (0.914±0.269). During the spring, the range of the change in the AOD was more intense, the aerosol particle size was larger than that during the summer and autumn, and the range of the variation in the particle size was larger. There was a negative correlation between the AOD and α. During the spring and summer, the aerosol particle size varied over a wide range, and the composition was more complex. With the decrease of the α, the AOD tended to increase; during the autumn, the dominant aerosol mode (mainly fine particles) stabilized, and the AOD exhibited no obvious change with the α. From spring to autumn, aerosol gradually transited from a coarse to fine mode. Compared with the summer, local aerosols were more sensitive to the changes of the wind speed, wind direction, and relative humidity during the spring. The primary reason for the increase of the AOD during the spring was the main wind direction and the dust input brought by gale weather. Influenced by the soluble salt ions in the dust, the aerosol particles were able to undergo hygroscopic growth, but this was not the main reason for the high AOD. Temperature was not the internal factor for the change in the local aerosols; however, it was directly proportional to the diffusion ability of aerosol particles. Overall, the AOD of Jinghe County was primarily affected by dust aerosols. The increases in the amounts of small particles and aerosol moisture absorption were not the main reasons for the increase of the AOD in this area.

Cylindrical IR-ATR Sensors for Process Analytics.

Infrared attenuated total reflection (ATR) spectroscopy is a common laboratory technique for the analysis of highly absorbing liquids and solids. However, in a process environment, maintaining a sufficient sample exchange and cleaning of the sensitive surface of the element is a crucial issue. An important industrial application is the measurement of isocyanate concentrations. Isocyanates are necessary for the fabrication of polyurethane materials and are among the chemicals with the highest production volume worldwide. For process applications, narrowband photometers or MEMS spectrometers are more appropriate than the use of bulky FTIR instruments frequently encountered in a laboratory environment. Toluene diisocyanate (TDI) and hexamethylene diisocyanate (HDI) concentrations are measured with a planar ATR photometer setup. Using a miniature Fabry-Perot interferometer (FPI), trace concentrations below 100 ppm (m/m) are detected. By employing an ATR element of the cylindrical shape, sensors can be realized with a smooth surface ideally suited for an automatic cleaning system in a process environment. A laboratory setup with sapphire tubes as ATR elements for incorporation in a liquid flow system is described. Reflection and transmission configurations were investigated. Measurements with acetonitrile as a less toxic substitute showed that with cylindrical ATR sensors' detection limits for isocyanate concentrations below 100 ppm (m/m) are feasible.

Evaluation of a New Workplace Protection Factor-Measuring Method for Filtering Facepiece Respirator.

BACKGROUND: This study aims to assess whether the TSI PortaCount (Model 8020) is a measuring instrument comparable with the flame photometer. This would provide an indication for the suitability of the PortaCount for determining the workplace protection factor for particulate filtering facepiece respirators. METHODS: The PortaCount (with and without the N95-Companion™) was compared with a stationary flame photometer from Moores (Wallisdown) Ltd (Type 1100), which is a measuring instrument used in the procedure for determining the total inward leakage of the particulate filtering facepiece respirator in the European Standard. Penetration levels of sodium chloride aerosol through sample respirators of two brands (A and B) were determined by the two measuring systems under laboratory conditions. For each brand, thirty-six measurements were conducted. The samples were split into groups according to their protection level, conditioning before testing, and aerosol concentration. The relationship between the gauged data from two measuring systems was determined. In addition, the particle size distribution inside the respirator and outside the respirator was documented. Linear regression analysis was used to calculate the association between the PortaCount (with and without the N95-Companion™) and the flame photometer. RESULTS: A linear relationship was found between the raw data scaled with the PortaCount (without N95-Companion™) and the data detected by the flame photometer (R2 = 0.9704) under all test conditions. The distribution of particle size was found to be the same inside and outside the respirator in almost all cases. CONCLUSION: Based on the obtained data, the PortaCount may be applicable for the determination of workplace protection factor.

The accuracy of artificial and natural light measurements by actigraphs.

Actigraphs are the reference standard for measuring light exposure in human non-laboratory experiments due to their portability and long battery lives. However, actigraphs typically have a limited illuminance operating range not representative of real-world conditions, and for many actigraphs, the accuracy of their light measurement has not been verified independently. We assessed the illuminances recorded by Activinsights GENEActiv Original and Philips Actiwatch 2 actigraphs in comparison to a calibrated, laboratory-standard photometer, under both artificial light-emitting diode (LED) and natural sunlight illuminations that might be encountered by a person under real-world conditions. We show that in response to ~20,000 lux white LED light, the GENEActiv and Actiwatch 2 underestimate illuminance by recording 50% and 25% of the true value, respectively. Under ~30,000 lux sunlight, the GENEActiv readily saturates whereas the Actiwatch 2 reports ~46% of the true illuminance. These underestimations are highly linear and we provide correction factors to estimate the illuminance levels of the ambient environment measured by the actigraphs. We also evaluate the application of neutral density filters for extending the operating range of both devices in natural sunlight illuminations (as high as 30,000 lux during our measurements) and demonstrate that this may be a viable approach for increasing the operating range of the Actiwatch 2 but not the GENEActiv. We conclude that both actigraphs provide good performance in monitoring the temporal patterning of light, whereas the absolute illuminance values require correction to accurately evaluate the effects of light intensity on human health and behaviours.

Development of a miniaturized photometer with paired emitter-detector light-emitting diodes for investigating thiocyanate levels in the saliva of smokers and non-smokers.

A simple, small and inexpensive photometer that uses a pair of light-emitting diodes (LEDs) and a simple operational amplifier was developed for investigating thiocyanate levels in saliva obtained from smokers and non-smokers. The photometer is based on paired emitter-detector diodes (PEDDs), and the entire system can be purchased for less than a hundred US dollars. The PEDD-based photometer can measure the transmittance of a solution in a 1-cm disposable polystyrene cuvette using only rechargeable dry-cell batteries, which makes it suitable for analysis outside of equipped laboratories. The metal complex formation between Fe (III) and thiocyanate ions in an acidic condition permits colorimetric detection of thiocyanate ions using LEDs emitting at 465 nm, because the complex shows maximum absorption at 457 nm. The developed photometer exhibits excellent performance with linearity ranging from 0.05 mmol L-1 to 0.75 mmol L-1 and a correlation coefficient (r2) > 0.999. The limits of detection and quantification were 0.01 mmol L-1 and 0.05 mmol L-1, respectively. Both intra- and inter-day precision were obtained with relative standard deviations (RSD) of less than 1% in the determination of thiocyanate. The proposed method is simple, facile, and sensitive enough to investigate the levels of thiocyanate in the saliva samples of smokers and non-smokers with centrifugation being the only special treatment for samples. The results showed that the concentrations of thiocyanate were approximately 5-fold higher in smokers than in non-smokers.