Characterization of nanoparticles in aerosolized photocatalytic and regular cement

Photocatalytic cement containing nano-TiO2 has been introduced to the construction industry because of its biocidal and self-cleaning properties. Although, TiO2 is classified as possibly carcinogenic to humans, the cancer risk among cement workers is currently unknown. This is partly because an assessment of exposures to airborne photocatalytic cement is missing. We characterized airborne photocatalytic cement in an experimental aerosolization set-up and compared it to regular cement. Aerosolized nanoparticle size distributions and concentrations were measured with a scanning mobility particle sizer (SMPS) and a portable aerosol spectrometer (PAS). Particle morphology was analyzed with a scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Energy dispersive X-ray analysis (SEM-EDX) was used for elemental determination. The aerosolized photocatalytic cement powder contained 5% nanosized particles in number concentration while regular cement had only a negligible amount. Airborne photocatalytic cement concentration was 14,900 particles per cubic centimeter (pt/cm3) with a geometric mean diameter (GMD) of 249 nm (geometric standard deviation; GSD ±2 nm). Airborne regular cement concentration and GMD (GSD) were 9,700 pt/cm3 and 417 nm (±2 nm), respectively. Photocatalytic cement contained 18.5 times more airborne nano-TiO2 (37%) compare to bagged powder (2%). Aerosolized photocatalytic cement had a significantly smaller particle size distribution and greater particle concentration compared to regular cement. Both types of cement had 99% of the particles with sizes less than 1 μm. Nano-TiO2 was directly aerosolized from the cement, followed with a coagulation/agglomeration process. Future studies should evaluate workers’ exposures associated with the use of photocatalytic cement. Copyright © 2019 American Association for Aerosol Research</p

Airborne reactive oxygen species (ROS) is associated with nano TiO2 concentrations in aerosolized cement particles during simulated work activities

Photocatalytic cement is self-cleaning due to the addition of titanium dioxide (TiO2) nanoparticles, which react with sunlight (UV) and produce reactive oxygen species (ROS). Construction workers using photocatalytic cement are exposed not only to cement particles that are irritants but also to nano TiO(2)and UV, both carcinogens, as well as the generated ROS. Quantifying ROS generated from added nano TiO(2)in photocatalytic cement is necessary to efficiently assess combined health risks. We designed and built an experimental setup to generate, under controlled environmental conditions (i.e., temperature, relative humidity, UV irradiance), both regular and photocatalytic cement aerosols. In addition, cement working activities-namely bag emptying and concrete cutting-were simulated in an exposure chamber while continuously measuring particle size distribution/concentration with a scanning mobility particle sizer (SMPS). ROS production was measured with a newly developed photonic sensing system based on a colorimetric assay. ROS production generated from the photocatalytic cement aerosol exposed to UV (3.3.10(-9) nmol/pt) was significantly higher than for regular cement aerosol, either UV-exposed (0.5.10(-9) nmol/pt) or not (1.1.10(-9) nmol/pt). Quantitatively, the level of photocatalytic activity measured for nano TiO2-containing cement aerosol was in good agreement with the one obtained with only nano TiO(2)aerosol at similar experimental conditions of temperature and relative humidity (around 60%). As a consequence, we recommend that exposure reduction strategies, in addition to cement particle exposures, also consider nano TiO(2)and in situ-generated ROS, in particular if the work is done in sunny environment

Absorbance enhancement in microplate wells for improved-sensitivity biosensors

A generic optical biosensing strategy was developed that relies on the absorbance enhancement phenomenon occurring in a multiple scattering matrix. Experimentally, inserts made of glass fiber membrane were placed into microplate wells in order to significantly lengthen the trajectory of the incident light through the sample and therefore increase the corresponding absorbance. Enhancement factor was calculated by comparing the absorbance values measured for a given amount of dye with and without the absorbance-enhancing inserts in the wells. Moreover, the dilution of dye in solutions with different refractive indices (RI) clearly revealed that the enhancement factor increased with the ΔRI between the membrane and the surrounding medium, reaching a maximum value (EF&gt;25) when the membranes were dried. On this basis, two H2O2-biosensing systems were developed based on the biofunctionalization of the glass fiber inserts either with cytochrome c or horseradish peroxidase (HRP) and the analytical performances were systematically compared with the corresponding bioassay in solution. The efficiency of the absorbance-enhancement approach was particularly clear in the case of the cytochrome c-based biosensor with a sensitivity gain of 40 folds and wider dynamic range. Therefore, the developed strategy represents a promising way to convert standard colorimetric bioassays into optical biosensors with improved sensitivity

Challenges in Quantifying 8-OHdG and 8-Isoprostane in Exhaled Breath Condensate

Exhaled breath condensate (EBC) has attracted substantial interest in the last few years, enabling the assessment of airway inflammation with a non-invasive method. Concentrations of 8-Hydroxydesoxyguanosine (8-OHdG) and 8-isoprostane in EBC have been suggested as candidate biomarkers for lung diseases associated with inflammation and oxidative stress. EBC is a diluted biological matrix and consequently, requires highly sensitive chemical analytic methods (picomolar range) for biomarker quantification. We developed a new liquid chromatography coupled to tandem mass spectrometry method to quantify 8-OHdG and 8-isoprostane in EBC simultaneously. We applied this novel biomarker method in EBC obtained from 10 healthy subjects, 7 asthmatic subjects, and 9 subjects with chronic obstructive pulmonary disease. Both biomarkers were below the limit of detection (LOD) despite the good sensitivity of the chemical analytical method (LOD = 0.5 pg/mL for 8-OHdG; 1 pg/mL for 8-isoprostane). This lack of detection might result from factors affecting EBC collections. These findings are in line with methodological concerns already raised regarding the reliability of EBC collection for quantification of 8-OHdG and 8-isoprostane. Precaution is therefore needed when comparing literature results without considering methodological issues relative to EBC collection and analysis. Loss of analyte during EBC collection procedures still needs to be resolved before using these oxidative stress biomarkers in EBC

The Transnational and the Text-Searchable: Digitized Sources and the Shadows They Cast

This working paper explores the consequences for historians' research practice of the twinned transnational and digital turns. The accelerating digitization of historians' sources (scholarly, periodical, and archival) and the radical shift in the granularity of access to information within them has radically changes historians' research practice. Yet this has incited remarkably little reflection regarding the consequences for individual projects or collective knowledge generation. What are the implications for international research in particular? This essay heralds the new kinds of historical knowledge-generation made possible by web access to digitized, text-searchable sources. It also attempts an accounting of all that we formerly, unwittingly, gained from the frictions inherent to international research in an analog world. What are the intellectual and political consequences of that which has been lost

Airborne nano-TiO 2 particles: an innate or environmentally-induced toxicity ?

Titanium oxide (TiO2) is a known photocatalyst, able to produce reactive oxygen species (ROS) when exposed to UV light. TiO2 phototoxicity has been abundantly demonstrated in aqueous solutions. Little is known; however, about its phototoxicity as an aerosol, particularly in the nano-size particle range. An experimental setting was developed to measure the oxidation capacity of TiO2 NP with or without exposure to UV light. TiO2 NP were generated using a Collison nebulizer, carried through a diffusion dryer and exposed to UV using the collimated beam of a solar light simulator. Their oxidation capacity was measured on-line via a photonic sensor based on multiscattering absorbance enhancement (MAE) strategy. The oxidative potential of aerosolized TiO2 nanoparticles is exacerbated by exposure to UV light. The oxidative response is affected by humidity and reaches its maximum in the 70%-90% relative humidity range. Gaseous hydrogen peroxide (H2O2) was found to be the predominant oxidative specie. Our results suggest that the use of TiO2 nanoparticles in outdoor environments or close to artificial UV sources lead to an involuntary exposure to ROS, to an extent greater than previously known. It raises also concerns about other environmental pollutants known to be UV photosensitive

GREEK-BERT: The Greeks visiting Sesame Street

Transformer-based language models, such as BERT and its variants, have achieved state-of-the-art performance in several downstream natural language processing (NLP) tasks on generic benchmark datasets (e.g., GLUE, SQUAD, RACE). However, these models have mostly been applied to the resource-rich English language. In this paper, we present GREEK-BERT, a monolingual BERT-based language model for modern Greek. We evaluate its performance in three NLP tasks, i.e., part-of-speech tagging, named entity recognition, and natural language inference, obtaining state-of-the-art performance. Interestingly, in two of the benchmarks GREEK-BERT outperforms two multilingual Transformer-based models (M-BERT, XLM-R), as well as shallower neural baselines operating on pre-trained word embeddings, by a large margin (5%-10%). Most importantly, we make both GREEK-BERT and our training code publicly available, along with code illustrating how GREEK-BERT can be fine-tuned for downstream NLP tasks. We expect these resources to boost NLP research and applications for modern Greek.Comment: 8 pages, 1 figure, 11th Hellenic Conference on Artificial Intelligence (SETN 2020

Lab-on-a-chip for multiplexed biosensing of residual antibiotics in milk

A multiplexed immunoassay-based antibiotic sensing device integrated in a lab-on-a-chip format is described. The approach is multidisciplinary and involves the convergent development of a multi-antibiotic competitive immunoassay based on sensitive wavelength interrogated optical sensor (WIOS) technology and a polymer-based self-contained microfluidic cartridge. Immunoassay solutions are pressure-driven through external and concerted actuation of a single syringe pump and multiposition valve. Moreover, the use of a novel photosensitive material in a one step fabrication process allowed the rapid fabrication of microfluidic components and interconnection port simultaneously. Pre-filled microfluidic cartridges were used as binary response rapid tests for the simultaneous detection of three antibiotic families – sulfonamides, fluoroquinolones and tetracyclines – in raw milk. For test interpretation, any signal lower than the threshold value obtained for the corresponding Maximum Residue Limit (MRL) concentration (100 µg L-1) was considered negative for a given antibiotic. The reliability of the multiplexed detection system was assessed by way of a validation test carried out on a series of six blind milk samples. A test accuracy of 95% was calculated from this experiment. The whole immunoassay procedure is fast (less than 10 minutes) and easy to handle (automated actuation)

Bridging the research-implementation gap in IUCN Red List assessments

The International Union for Conservation of Nature (IUCN) Red List of Threatened Species is central in biodiversity conservation, but insufficient resources hamper its long-term growth, updating, and consistency. Models or automated calculations can alleviate those challenges by providing standardised estimates required for assessments, or prioritising species for (re-)assessments. However, while numerous scientific papers have proposed such methods, few have been integrated into assessment practice, highlighting a critical research-implementation gap. We believe this gap can be bridged by fostering communication and collaboration between academic researchers and Red List practitioners, and by developing and maintaining user-friendly platforms to automate application of the methods. We propose that developing methods better encompassing Red List criteria, systems, and drivers is the next priority to support the Red List.Peer reviewe