Biofilm dynamics characterization using a novel DO-MEA sensor: mass transport and biokinetics

Biodegradation process modeling is an essential tool for the optimization of biotechnologies related to gaseous pollutant treatment. In these technologies, the predominant role of biofilm, particularly under conditions of no mass transfer limitations, results in a need to determine what processes are occurring within the same. By measuring the interior of the biofilms, an increased knowledge of mass transport and biodegradation processes may be attained. This information is useful in order to develop more reliable models that take biofilm heterogeneity into account. In this study, a new methodology, based on a novel dissolved oxygen (DO) and mass transport microelectronic array (MEA) sensor, is presented in order to characterize a biofilm. Utilizing the MEA sensor, designed to obtain DO and diffusivity profiles with a single measurement, it was possible to obtain distributions of oxygen diffusivity and biokinetic parameters along a biofilm grown in a flat plate bioreactor (FPB). The results obtained for oxygen diffusivity, estimated from oxygenation profiles and direct measurements, revealed that changes in its distribution were reduced when increasing the liquid flow rate. It was also possible to observe the effect of biofilm heterogeneity through biokinetic parameters, estimated using the DO profiles. Biokinetic parameters, including maximum specific growth rate, the Monod half-saturation coefficient of oxygen, and the maintenance coefficient for oxygen which showed a marked variation across the biofilm, suggest that a tool that considers the heterogeneity of biofilms is essential for the optimization of biotechnologies.Peer ReviewedPostprint (published version

Evaluation of mass transfer coefficients in biotrickling filters: experimental determination and comparison to correlations

This is the pre-peer reviewed version of the following article: Dorado, A.D. [et al.]. Evaluation of mass transfer coefficients in biotrickling filters: experimental determination and comparison to correlations. "Chemical engineering and technology", Setembre 2009, vol. 32, núm. 12, p. 1941-1950, which has been published in final form at https://doi.org/10.1002/ceat.200900275. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.Overall mass transfer coefficients (KGa and KLa) were determined experimentally for four different-nature packing materials used in gas-phase biotrickling filters. A simple methodology based on overall mass balances and following a standard procedure allowed to calculate the mass transfer coefficients under different operating conditions corresponding to usual biotrickling filtration situations. Results showed an increase of mass transfer resistance when increasing the empty bed residence time (EBRT) of the reactor for all packing materials. Experimental results were fitted to existing and well-accepted correlations used in conventional biofilter or biotrickling filter modeling. The comparison of experimental and theoretical data showed huge discrepancies. Simple correlations for the experimental data obtained in this study were also suggested.Peer ReviewedPostprint (author's final draft

Dynamic characterization of external and internal mass transport in heterotrophic biofilms from microsensors measurements

Peer ReviewedPreprin

A novel MEMS-based sensor for simultaneous pH and dissolved oxygen profiling in biofilms

Peer ReviewedPostprint (published version

System to control indoor air quality in energy efficient buildings

This work looks at monitoring air quality in indoor environments through the integration of several sensing technologies into a single robust, reliable and cheap detection platform, which shares air pre-conditioning and electronics. Target gases and detection limits have been set according to recommendations of different agencies in Europe and the US. The system has reached detection limits stated by the OSHA (Occupational Safety and Health Administration) for benzene. The pre-conditioning fluidic platform has also been designed, simulated, fabricated and tested with sensors so the gas flow has been optimized. Field tests in real buildings are being carried out to contrast current measurement procedures and results with the obtained using the device under development. The main aim of the system is to control HVAC (Heat Ventilation and Air Conditioning) in energy-efficient way while keeping a high air quality standard inside the building

Development of a novel microsensor for the study of oxygen profiles in biofilms

Understanding of the processes taking place inside biofilms is a key parameter to progress in the optimization of biofiltration technologies. This study was conducted with the aim of developing a novel dissolved oxygen (DO) microsensor specially designed for biofilms monitoring. The microsensor was fabricated through standard photolithography techniques, resulting in a microelectrodes array (MEA) of 11 gold circular working electrodes, with a diameter of 50 µm , and a gold reference electrode, which allows obtaining a snapshot oxygen profile of 1 mm of depth. The performance of the sensor was fully characterized under different conditions, inwhich the sensor presented high sensitivity and repeatability, and low detection and quantification limits. Monitoring of sensor performance showed a stable and reliable response. The developed sensor was used in obtaining micropofiles in an aerobic heterotrophic biofilm, showing similar response to Clark-type commercial microsensors. These studies concluded that the novel MEA sensor for DO monitoring allows obtaining oxygen profiles within biofilms, becoming a useful tool for the research of many biological applications.Postprint (author's final draft

Athletes' exposure to air pollution during World Athletics Relays: A pilot study

Potential adverse consequences of exposure to air pollutants during exercise include decreased lung function, and exacerbation of asthma and exercise-induced bronchoconstriction. These effects are especially relevant for athletes and during international competitions, as they may impact athletic performance. Thus, assessing and mitigating exposure to air pollutants during exercising should be encouraged in sports venues. A comprehensive air quality assessment was carried out during the World Relays Yokohama 2019, in the stadium and the warm-up track. The pilot included on-line and off-line instrumentation for gaseous and particulate pollutants and meteo- rological parameters, and the comparison with local reference data. Air quality perception and exacerbation of symptoms of already-diagnosed diseases (mainly respiratory and cardiovascular) were assessed by athletes by means of questionnaires during training sessions. Median NO2 concentrations inside the stadium (25.6–31.9 μgm−3) were in the range of the Yokohama urban background, evidencing the impact of urban sources (e.g., traffic) on athletes' exposure during training and competition. The assessment of hourly air pollutant trends was identified as a valuable tool to provide guidance to reduce atheletes' exposure, by identifying the periods of Inhalation Track and field Respiratory diseases World Athletics 1. Introduction Evidence supports adverse effects from short-term and long-term inhalation of air pollution to the respiratory and the cardiovascular sys- tems (Brook et al., 2002; Pietropaoli et al., 2004; Gauderman et al., 2007; de Prado Bert et al., 2018). Health impacts have been assessed for gen- eral and high-risk populations, and even for general populations performing physical activities such as walking or cycling while com- muting (de Nazelle et al., 2012; Hofman et al., 2018; Luengo-Oroz and Reis, 2019; Qiu et al., 2019; Quiros et al., 2013; Rivas et al., 2014). How- ever, research is scarce on the effects of ambient air pollution on exercis- ing athletes and their athletic performance, who may have greater than average susceptibility and exposure to air pollutants because of the physiological changes that occur during prolonged exercise (Quin et al., 2019). Specifically, there are 3 reasons why athletes are at higher risk from air pollution (McCafferty, 1981): (1) increased ventilation during exer- cise; (2) a greater fraction of air is inhaled through the mouth during ex- ercise, effectively bypassing the normal nasal filtration mechanisms; and (3) the increased airflow velocity carries pollutants deeper into the respiratory tract. Furthermore, pulmonary diffusion capacity in- creases with exercise (Turcotte et al., 1997; Stokes et al., 1981; Fisher and Cerny, 1982; Flaherty et al., 2013), increasing gaseous pollutant in- take. Nasal mucociliary clearance, impaired in long-distance runners, may also contribute to the higher susceptibility of endurance athletes given that pollutants which are normally cleared from the respiratory system, are instead absorbed (Atkinson, 1987). Even though research is scarce, studies on the relationship between air quality, athletic performance, and respiratory symptoms encourage pursuing further investigations. Lichter et al. (2015) assessed the effects of particulate air pollution on soccer players in German stadiums, re- vealing that performance was reduced under poor air quality condi- tions. Bos et al. (2011) and Quin et al. (2019) observed that the health benefits of active commuting could be negatively influenced by exercis- ing in polluted environments, while Rundell and Caviston (2008) re- ported that the acute inhalation of PM1 at concentrations in the range of many urban environments could impair exercise performance. Carlisle and Sharp (2001) and Cakmak et al. (2011) concluded that O3 was particularly damaging to athletes, with subjects achieving a lower aerobic fitness score on high ozone days. Finally, long-term exposure to outdoor air pollution may trigger intermittent endogenous airway acidification episodes indicative of pollution-related lung inflammation (Ferdinands et al., 2008). These results have particularly relevant impli- cations for top-level athletes participating in international competi- tions: the performance of athletes training in highly polluted environments may be impaired compared to athletes training in cleaner environments and, similarly, athletes used to training in cleaner envi- ronments may be adversely affected when competing in highly polluted locations. Thus, assessing exposure to air pollution in athletics venues becomes a necessity when aiming at understanding environmental drivers of both athletic performance, and athletes' health. In this framework, the aim of this study was to characterize air pol- lutant concentrations in the Yokohama stadium (in the competition and the training area) during the Yokohama 2019 World Relays the day with lowest ambient concentrations. This strategy could be adopted to define training and competition schedules, and would have special added value for athletes with respiratory conditions. Personal exposure to polycyclic aromatic hydrocarbons was quantified through wearable silicone wristbands, and showed highly var- iability across volunteers. The wristbands are a simple approach to assess personal exposure to potentially toxic organic compounds. Further research would be necessary with regard to specific air pollutants that may trigger or exacerbate respiratory conditions typical of the athlete community. The availability of high time-resolved ex- posure data in the stadiums opens up the possibility to calculate doses of specific pollutants for individual ath- letes in future athletics events, to understand the impact of environmental factors on athletic performance

Rainfall homogenizes while fruiting increases diversity of spore deposition in Mediterranean conditions

There is a lack of knowledge regarding the main factors modulating fungal spore deposition in forest ecosystems. We have described the local spatio-temporal dynamics of fungal spore deposition along a single fruiting season and its relation with fruit body emergence and rainfall events. Passive spore traps were weekly sampled during autumn and analysed by metabarcoding of the ITS2 region in combination with qPCR. There were larger compositional changes of deposited spores across sampling weeks than amongst sampling plots. Spore diversity and abundance correlated with mushroom emergence and weekly rainfall. Spore compositional changes were related to rainfall, with lower spatial compositional heterogeneity across plots during weeks with higher rainfall. Soil saprotrophs, and amongst them, puffball species, showed the strongest positive correlation with rainfall across fungal guilds. We saw high fine-scale temporal changes of deposited spores, and both mushroom emergence and rainfall may be important factors driving airborne spore deposition.This work was partially supported by the Spanish Ministry of Science, Innovation and Universities, grants N° AGL2015-66001-C3, RTI2018-099315-A-I00, the CERCA Programme / Generalitat de Catalunya, and by the European project StarTree (No. 311919). J.G.A. was supported by Juan de la Cierva (Grant number IJCI-2014-21393) and Ramon y Cajal fellowships (RYC-2016-20528), while JO was supported by Ramon y Cajal fellowship (RYC-2015-17459). José Antonio Bonet benefitted from a Serra-Húnter Fellowship provided by the Generalitat of Catalunya. Carles Castaño received the support of the Secretaria d’Universitats i Recerca del Departament d’Economia i Coneixement de la Generalitat de Catalunya through the program of Doctorats Industrials, and benefitted from a STSM grant from COST Action FP1203

Biofilm oxygen profiling using an array of microelectrodes on a microfabricated needle

A novel microelectrode array (DO-MEA) sensor was designed and fabricated using microelectromechanical systems technology on a needle for real time measurement of dissolved oxygen (DO). The sensor consisted of eleven gold disk microelectrodes and a rectangular auxiliary electrode along them. The sensor can also be operated with an integrated reference system. Three different sensor designs were fabricated, and their responses were fully characterized and evaluated. The DO-MEA sensor presented a linear response in the 0-8 mg DO·L-1 concentration range in water, displaying high sensitivity and repeatability. Knowledge of bacterial activity inside biofilms is key to the optimization of applied biotechnologies. The developed sensor was validated against a commercial Clark-type microelectrode overcoming its drawbacks, by profiling a heterotrophic biofilm cultivated in a flat-plate bioreactor. The DO-MEA sensor provided a multipoint, simultaneous dissolved oxygen snapshot profile inside a biofilm with high spatial resolution due to its micrometric dimensions, thus becoming a powerful tool for the research of many similar biological-based processes and applications.Peer ReviewedPostprint (author’s final draft

Lifetime exposure to brominated trihalomethanes in drinking water and swimming pool attendance are associated with chronic lymphocytic leukemia: a Multicase-Control Study in Spain (MCC-Spain)

Background: Chronic lymphocytic leukemia (CLL) etiology is poorly understood, and carcinogenic chemicals in drinking and recreational water are candidates. Objective: To evaluate the association between drinking-water exposure to trihalomethanes (THMs) and nitrate as well as lifetime swimming pool attendance and CLL. Methods: During 2010-2013, hospital-based CLL cases and population-based controls were recruited in Spain, providing information on residential histories, type of water consumed and swimming pool attendance. Average THMs and nitrate levels in drinking water were linked to lifetime water consumption. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using mixed models. Results: Final samples for residential tap water analyses and swimming pool attendance analyses were 144 cases/1230 controls and 157 cases/1240 controls, respectively. Mean (SD) values for average lifetime residential brominated THMs and chloroform in tap water (μg/L), and ingested nitrate (mg/day) were 48.1 (35.6), 18.5 (6.7) and 13.7 (9.6) respectively in controls; and 72.9 (40.7), 17.9 (5.4), and 14.1 (8.8) in CLL cases. For each 10 μg/L increase of brominated THMs and chloroform lifetime-average levels, the ORs (95% CI) were 1.22 (1.14, 1.31) and 0.54 (0.34, 0.87), respectively. For each 5 mg/day increase of ingested nitrate, the OR of CLL was 0.91 (0.80, 1.04). The OR of lifetime pool users (vs. non-users) was 2.38 (1.61, 3.52). Upon performing annual frequency of attending pools analysis through categorization, the second and third categories showed an ORs of 2.36 (1.49, 3.72) and 2.40 (1.51, 3.83), respectively, and P-trend of 0.001. Impact statement: This study identifies an association of long-term exposure to THMs in drinking water, at concentrations below the regulatory thresholds and WHO guidelines, and swimming pool attendance, with chronic lymphocytic leukemia (CLL). These unprecedented findings are highly relevant since CLL is an incurable cancer with still unknown etiology and because the widespread exposure to chlorination by-products that remain in drinking and recreational water worldwide. Despite the demonstrated carcinogenicity in animals of several chlorination by-products, little is known about their potential risks on human health. This study makes a significant contribution to the search for environmental factors involved in the etiology of CLL and to the evidence of the health impact of these high prevalent water contaminants.The study was partially funded by the “Accion Transversal del Cancer”, approved on the Spanish Ministry Council on the 11th October 2007, by the Instituto de Salud Carlos III-FEDER (PI08/1770, PI08/0533, PI08/1359, PS09/00773, PS09/01286, PS09/01903, PS09/02078, PS09/01662, PI11/01889, PI11/00226, PI12/01270, PI12/00715, PI14/0613, PI15/00914, PI17CIII/00034), by the Fundación Marqués de Valdecilla (API 10/09), by the Conselleria de Sanitat of the Generalitat Valenciana (AP_061/10), by the European Commission grants FOOD-CT-2006-036224-HIWATE, by the Spanish Association Against Cancer (AECC) Scientific Foundation, by the Catalan Government Agency for Management of University and Research Grants (AGAUR) grants 2017SGR723, 2021SGR01354 and 2014SGR850, by the Fundación Caja de Ahorros de Asturias and by the University of Oviedo. ISGlobal acknowledges support from the Spanish Ministry of Science and Innovation through the “Centro de Excelencia Severo Ochoa 2019-2023” Program (CEX2018-000806-S), and support from the Generalitat de Catalunya through the CERCA Program.S