Challenges in quantification of photocatalytic NO2 abatement effectiveness under real world exposure conditions illustrated by a case study

Health risks due to NO₂ exposure commonly exceed acceptable levels in modern societies. Among the measures to reduce such risks, photocatalytic materials present a promising technology. However, while the pollutant remediation of such materials has been extensively validated in laboratory studies, the performance under real world environmental exposure conditions is still subject to controversy. Indeed, a comparison of available in-situ monitoring studies manifests non-conclusive and highly scattered results regarding the photocatalytic effectiveness observed. The reasons for this behaviour must be carefully explored in order to prevent non-efficient photocatalytic applications from being put into practice on a larger scale. This paper presents a comprehensive large-scale study for assessing the photocatalytic NO₂ remediation by active pavements in a street of Madrid (Spain), comprising different in-situ monitoring techniques. The discussion is enriched by relating the obtained results to those of other large-scale studies. The discrepancies between these results may be traced back to different circumstances, among them the distance between the active pavement and the pollutant concentration sampling inlet, as well as to significant site-specific and time-dependent variations of pollutant concentrations and climatic parameters. Under due consideration of these influences, for materials with relatively high initial effectiveness, it was concluded that in most such applications, the average NO₂ removal effectiveness, if evaluated at a typical inlet height of Air Quality Stations (3 m), will not exceed a value of 4% (averaged over a sufficiently large number of measurement points in the area of application and a sustained amount of time, i.e. several months). When considering more realistic human exposure conditions (lower heights and daytime), it might be justified to assume somewhat higher average effectiveness.

Predicting the Olea pollen concentration with a machine learning algorithm ensemble

Air pollution in large cities produces numerous diseases and even millions of deaths annually according to the World Health Organization. Pollen exposure is related to allergic diseases, which makes its prediction a valuable tool to assess the risk level to aeroallergens. However, airborne pollen concentrations are difficult to predict due to the inherent complexity of the relationships among both biotic and environmental variables. In this work, a stochastic approach based on supervised machine learning algorithms was performed to forecast the daily Olea pollen concentrations in the Community of Madrid, central Spain, from 1993 to 2018. Firstly, individual Light Gradient Boosting Machine (LightGBM) and artificial neural network (ANN) models were applied to predict the day of the year (DOY) when the peak of the pollen season occurs, resulting the estimated average peak date 149.1 ± 9.3 and 150.1 ± 10.8 DOY for LightGBM and ANN, respectively, close to the observed value (148.8 ± 9.8). Secondly, the daily pollen concentrations during the entire pollen season have been calculated using an ensemble of two-step GAM followed by LightGBM and ANN. The results of the prediction of daily pollen concentrations showed a coefficient of determination (r²) above 0.75 (goodness of the model following cross-validation). The predictors included in the ensemble models were meteorological variables, phenological metrics, specific site-characteristics, and preceding pollen concentrations. The models are state-of-the-art in machine learning and their potential has been shown to be used and deployed to understand and to predict the pollen risk levels during the main olive pollen season.

Assessment and statistical modelling of airborne microorganisms in Madrid

The limited evidence available suggests that the interaction between chemical pollutants and biological particles may intensify respiratory diseases caused by air pollution in urban areas. Unlike air pollutants, which are routinely measured, records of biotic component are scarce. While pollen concentrations are daily surveyed in most cities, data related to airborne bacteria or fungi are not usually available. This work presents the first effort to understand atmospheric pollution integrating both biotic and abiotic agents, trying to identify relationships among the Proteobacteria, Actinobacteria and Ascomycota phyla with palynological, meteorological and air quality variables using all biological historical records available in the Madrid Greater Region. The tools employed involve statistical hypothesis contrast tests such as Kruskal-Wallis and machine learning algorithms. A cluster analysis was performed to analyse which abiotic variables were able to separate the biotic variables into groups. Significant relationships were found for temperature and relative humidity. In addition, the relative abundance of the biological phyla studied was affected by PM₁₀ and O₃ ambient concentration. Preliminary Generalized Additive Models (GAMs) to predict the biotic relative abundances based on these atmospheric variables were developed. The results (r = 0.70) were acceptable taking into account the scarcity of the available data. These models can be used as an indication of the biotic composition when no measurements are available. They are also a good starting point to continue working in the development of more accurate models and to investigate causal relationships.

NOx removal efficiency of urban photocatalytic pavements at pilot scale

Photocatalytic technology implemented in construction materials is a promising solution to contribute to alleviate air quality issues found in big cities. Photocatalysis has been proved able to mineralise most harmful contaminants. However, important problems associated with monitoring the efficiency of these solutions under real conditions still remain, including the lack of affordable analytical tools to measure NO_x concentrations with enough accuracy. In this work, two pilot scale demonstration platforms were built at two different locations to assess the photocatalytic NO_X removal efficiency of ten selected materials exposed outdoors for AQmesh low-cost sensor PODs were used to measure ground-level to measure NO and NO₂ concentrations during nearly one year. The pollutant removal efficiency of the materials was then calculated based on a comparison with simultaneously concentration measurements carried-out on reference, non-active materials. It was found that the NO₂ removal efficiency presented large variations across the seasons, with maxima during the warmer months, while NO efficiencies were comparatively steadier. Statistical analysis delivered evidence that the efficiencies significantly depend on different meteorological variables (irradiance and relative humidity) besides NO, NO₂ ambient concentrations. Lower efficiencies were observed for higher concentration levels and vice versa. The influence of water vapour could be related to two different effects: a short-term contribution by the instantaneous air humidity and a long-term component associated with the hygroscopic state of the material. The contribution of wind to the pollutant removal efficiencies was principally related to the humidity of air masses moving above the location and to the advection of pollutants from specific emission sources.

[Radioguided surgery in neuroendocrine tumors. A review of the literature]

Radioguided surgery can be a useful technique in the localization of neuroendocrine tumors. It detects more and smaller lesions compared to pre-surgical imaging and intraoperative digital palpation by the surgeon. It detects residual lesions and also indicates the shortest access route to the lesion. Nevertheless, its use has not become widespread because of technical difficulties. There is a limited number of published series, a lack of standardized protocol because of the great variability regarding type of radiopharmaceutical, dose of radiotracer, timing between injection and surgery. In this paper, we review these issues, describing the experience of different authors in diverse tumors.

[Study of the sentinel node in breast cancer using lymphoscintigraphy and a fast method for cytokeratin]

INTRODUCTION

Histopathological examination of the axillary sentinel node (SN) is becoming a routine procedure in the surgical phase of infiltrating ductal carcinoma of the breast (IDC). The SN exam may yield false negative cases mainly due to identification failure of the SN but some of the false negative cases may be the result of the pathological examination procedure applied.

MATERIAL AND METHODS

Sixty two (62) cases of clinically staged N0 IDC of the breast by TNM nomenclature were assigned to breast surgery along with conventional axillary node dissection. The identification technique included lymphoscintigraphy and intraoperative gamma-detecting probe after peritumoral injection of 99mTc-labeled colloids.The histological study of SN was performed with paired 4 microm slices and staining with hematoxylin-eosin and with a fast method of cytokeratins for freezing.

RESULTS

In only two of the 62 patients, it was not possible to identify the SN. Eighteen of the remaining 60 had SN involvement by metastasis, having no metastases in the other nodes of the axillary dissection in 6 of them. Ten of those were micrometastasis (size of metastasis= or <0.2 cm). In two out of these last 10 cases, diagnosis of the micrometastasis was only possible using slices stained with CK. There were no false negative results.

CONCLUSIONS

The lymphoscintigraphy, after peritumoral injection of small volumes and low dose of the tracer, makes it possible to obtain excellent results in the intraoperative detection of the SN in breast cancer. The study of this SN with a fast method for CK decreases the number of false negative results of the technique.

Effect of the treatment of Helicobacter pylori infection on gastric emptying and its influence on the glycaemic control in type 1 diabetes mellitus

Helicobacter pylori (Hp) infection plays a role in gastric emptying (GE) in type 1 diabetic patients and may have implications for glycaemic control. The aim of our study was to investigate this relationship. Gastric emptying was studied in 13 patients with type 1 diabetes and Hp infection. The Hp infection status was assessed by serology and urease breath test (UBT). In addition upper gastrointestinal endoscopy with gastric mucosal biopsy was performed to look for gastritis. A radionuclide-labeled solid meal was used to study GE before and after eradication therapy (amoxicillin, clarithromycin and omeprazole) for Hp infection. All patients were evaluated for autonomic and peripheral neuropathy and were asked for symptoms of gastrointestinal motor dysfunction. Blood glucose levels were determined before the meal and at 30,60,90 and 120 min after the start of the meal. Home blood glucose self-monitoring and HbA(1c) were performed to document glycaemic control during the study. Three months after treatment, five patients were free of Hp infection and were without gastritis (group I: no Hp infection, no gastritis); eight of the patients continued to have gastritis after treatment (group II) and of these eight patients, six had gastritis without Hp infection and two had gastritis plus persistent Hp infection. These last two patients were re-treated with eradication therapy. Patients with gastritis were re-evaluated 6 months after initial treatment; at which time four were now free of gastritis and were added to group I (n=9) while four continual to have gastritis although without Hp infection (group II, n=4). In group I, GE half-time showed an increase (30.6+/-10.3 min vs. 60.2+/-15.4 min; P<0.05) while no change (28.8+/-9.5 vs. 26.9+/-8.7 min; n.s.) was observed in group II. GE half-time was not altered by autonomic and peripheral neuropathy or blood glucose during solid meal test. HbA(1c) did not change significantly after treatment in either groups but the blood glucose levels were more stable in group I compared to group II. A delay in GE was observed with disappearance of gastritis associated to H. pylori infection after eradication treatment in patients with type 1 diabetes. This change in GE could help to stabilise the blood glucose levels in these patients treated with insulin before each meal.

[Utilization of a post-anesthetic recovery index]

OBJECTIVES

1. To introduce use of the postanesthesia recovery score (assessing consciousness, mobility, ventilation, hemodynamics and blood analysis) as a good method for evaluating and classifying recovery from anesthesia in the postoperative care unit. 2. To determine overall patient progress and assess the influence of various patient, anesthetic and surgical factors.

PATIENTS AND METHODS

This was a multicenter study of 1,227 patients. We excluded all patients who were to be transferred to intensive care units after surgery. A score of 10 or more, with no single item score equal to 0, was considered optimal for discharge from the postanesthesia care unit.

RESULTS

The lowest score upon admission to the unit was among patients who had undergone high abdominal surgery (16.4%). Scores over 9 belonged to patients who had undergone lower abdominal and perineal surgery (87.5 and 95.3%, respectively). Scores were < or = 9 in patients who received inhaled anesthetics (42%). Intravenous anesthesia patients (84.4%) had scores over 9. The local-regional anesthetic procedures with the best scores were axilar blocks and local infiltrations. Patients staying longer in the recovery unit were those classified as ASA III, those whose procedures lasted longer than 120 minutes, those undergoing surgery on the upper abdomen or on extremities, those receiving isoflurane and pancuronium, and those suffering adverse events during and after the procedure. Factors influencing perioperative events were age, duration of procedure and history of intraoperative events.

[Analysis of preoperative reserve criteria and intraoperative transfusion of blood derivatives at an anesthesiology and recovery service]

Three hundred and three patients undergoing elective surgery were studied prospectively. Patient data and results of serial blood cell counts were recorded before and after surgery and used to evaluate the criteria used to reserve and transfuse blood and blood products, as well as to assess the outcome of transfusions performed. Six hundred and ninety-nine units were reserved, indicating a reservation-to-transfusion ratio of 1.8. The most often cited reasons for reserving blood were surgical technique, nature of disease and prolonged surgery. A high number of reservations were called for from the ward by the surgeons themselves. A total of 180 patients were given transfusions, the main reason being the anesthesiologist's judgement that the Hb count was low (in 26% of cases). Transfusions because of slight bleeding during surgery and prolonged surgery gave rise to the highest Hb counts. The lowest post-transfusion Hb counts recorded occurred when the reason cited was presence of signs of anemia. We conclude that the ratio of reservations to transfusions in our study was acceptable, as were the reasons justifying reserves. There is an overall tendency to achieve excessively high Hb counts (10-11 g/dl) in the early postoperative period. The best criterion for performing transfusion is the presence of signs of anemia.

[Adrenergic response during general anesthesia with propofol as maintenance agent]

To determine plasma catecholamine levels during the use of propofol for maintenance of anesthesia. We studied 20 randomly chosen patients undergoing elective orthopedic surgery under general intravenous anesthesia with propofol as the agent of maintenance along with pancuronium and fentanyl. Plasma concentrations of dopamine, noradrenalin and adrenalin were measured at the following times: baseline, after intubation and every 15 min during surgery. The levels obtained for the different samples were compared with baseline levels. At the doses used in our study, there were no significant differences in the way dopamine plasma levels varied. This was not the case with the other two hormones, however. Adrenalin levels were significantly higher at the first 3 extractions (post-intubation, 15 min and 30 min), and noradrenalin was significantly higher (p < 0.05) at all extraction times. Total intravenous anesthesia with propofol is associated with a significant increase in plasma concentrations of adrenalin and noradrenalin. Adrenalin returns to baseline levels 45 min after induction.

Superficial radiotherapy of warts: results of treating 531 warts

The fear of injurious effects has almost completely halted the use of radiotherapy in the cure of warts. Over a period of 24 years, the authors have treated 531 warts with both orthovoltage and superficial radiation equipment without any adverse effects. The selection of superficial or orthovoltage units was not dependent on the size of the lesion and was thought to be completely random.