Threat of allergenic airborne grass pollen in Szczecin, NW Poland: the dynamics of pollen seasons, effect of meteorological variables and air pollution

The dynamics of Poaceae pollen season, in particularly that of the Secale genus, in Szczecin (western Poland) 2004–2008 was analysed to establish a relationship between the meteorological variables, air pollution and the pollen count of the taxa studied. Consecutive phases during the pollen season were defined for each taxon (1, 2.5, 5, 25, 50, 75, 95, 97.5, 99% of annual total), and duration of the season was determined using the 98% method. On the basis of this analysis, the temporary differences in the dynamics of the seasons were most evident for Secale in 2005 and 2006 with the longest main pollen season (90% total pollen). The pollen season of Poaceae started the earliest in 2007, when thermal conditions were the most favourable. Correlation analysis with meteorological factors demonstrated that the relative humidity, mean and maximum air temperature, and rainfall were the factors influencing the average daily pollen concentrations in the atmosphere; also, the presence of air pollutants such as ozone, PM10 and SO2 was statistically related to the pollen count in the air. However, multiple regression models explained little part of the total variance. Atmospheric pollution induces aggravation of symptoms of grass pollen allergy

New findings of airborne fungal spores in the atmosphere of Havana, Cuba, using aerobiological non-viable methodology

Introduction. Although airborne fungal diversity in tropical countries is known to be considerable, aerobiological research to-date has identified only a part of the fungal mycobiota that may have an impact both on human health and on crops. Previous studies in Havana city identified only 30 genera and 5 spore types; therefore,new research is required in these latitudes. This study sought to investigate airborne spore levels in Havana, with a view to learning more about local fungal diversity and assessing its influence in quantitative terms. Materials and method. A Hirst type volumetric sampler was located on the rooftop of a building 35 meters above ground level, in a busy area of the city. Sampling was carried out continuously (operating 24hours/day), at 10 L per minute during the year 2015. The fungal spores were collected on a Melinex tape coated with a 2% silicone solution. The results were expressed as spores per cubic meter (spores/m3) of air when to referring to daily values, and spores count if referring to annual value. Results. Fourteen new genera were identified in the course of volumetric sampling: six produce ascospores and eight conidia. Morphobiometric characteristics were noted for all genera, and airborne concentrations were calculated. These genera accounted for 56.4% of relative fungal frequency over the study year. Conclusions. Many airbone fungi are primary causes of both respiratory disease and crop damage. These new findings constitute a major contribution to Cuba’s aerobiological database

Post-hot isostatic pressing: A healing treatment for process related defects and laboratory grinding damage of dental zirconia?

Objective. Processing parameters (powder granulation, compaction, debinding, greenbody shaping, sintering) and post-sinter rough, even fine grinding are influencing the final mechanical properties of 3Y-TZP. The hypothesis of this study was that post-sinter hot isostatic pressing (post-HIP) would be beneficial for improving reliability and strength of both sintered and coarse ground sintered zirconia by closing or reducing surface and/or small volume defects. Methods. 75 sintered bars of an experimental 3Y-TZP (3 mm × 4 mm × 45 mm) with chamfered edges and 15 μm diamond surface finish were provided by the manufacturer (Ivoclar Vivadent) and randomly distributed in five groups of N = 15 each. G1 served as control (as received); G2 was post-HIPed at 1400 ◦C and G3 at 1350 ◦C, both using a pressure of 195 MPa in Ar for 1 h; G4 was coarse ground with 120 μm diamond disk grain size; G5 was ground 120 μm and post-HIPed at 1350 ◦C at 195 MPa, 1 h in Ar. The specimens were fractured in air in 4 point-bending. Weibull characteristic strength (σ0) in MPa, m parameter (reliability) and confidence intervals (CI) at 90% confidence level are reported. Identification of the critical flaw was performed by SEM on the fractured surface of all specimens and XRD performed in all groups. Results. G1: σ0 = 973 (932–1016), m = 10.6 (7.45–15.1); G2: σ0 = 930 (871–995), m = 6.9 (4.87–9.9); G3: σ0 = 898 (848–952), m = 7.94 (5.6–11.4); G4: σ0 = 921 (857–991), m = 6.35 (4.48–9.11); G5: σ0 = 881 (847–918), m = 11.4 (8.03–16.3). G5 had a significantly lower σ0 than G1. No significant differences were seen in the reliability (m) among the groups. Fractography revealed critical intrinsic subsurface flaws of 10–60 μm present in all groups resulting from the processing parameters. No “healing” (i.e. closing of defects by densification) resulted after post-HIP. Grinding sintered zirconia with 120 μm diamond disks induced radial cracks of 10–20 μm and an important pseudo-cubic phase transformation (56 wt%) that was not completely removed after post-HIP. Post-HIP increased slightly the relative density by 0.1% but without improving the strength and reliability