Filtration performances of HVAC filters for PM10 and microbial aerosols— Influence of management in a lab-scale air handling unit

Filtration performances of air handling unit (AHU) filters for particles and microbial aerosols were investigated. The influence of the AHU operational conditions on the behavior of microorganisms collected on the filters was also studied. A lab-scale AHU with two filtration stages was developed and validated for the study of downsized filters with industrial geometries. Three types of filters of different efficiency were considered: G4, F7, and F9, according to European standard EN 779. Two configurations of filters were studied: G4 pleated/F7 bag and F7/F9 bag. Filters were sequentially clogged by alumina particles, which provided a mineral fraction in the particulate cake, and then by micronized rice particles, which provided the fungus Penicillium chrysogenum and an organic fraction that acts as a substrate for microorganisms. Finally, a microbial aerosol composed of endospores of Bacillus subtilis and spores of Aspergillus niger was nebulized to contaminate filters. After clogging, periods of 5 days on and 2 day weekend stops with restarts of ventilation were simulated for 6 weeks. The results showed that the filter efficiency for particles was quite comparable to that for microbial aerosols expressed in cultivable concentration. The particulate cake composed of alumina and micronized rice particles enabled the growth of the endogenous species P. chrysogenum and the survival of exogenous species B. subtilis and A. niger on filters. During restarts of ventilation, low particle concentrations were detected downstream of the second filtration stages by release but the microbial concentration from the fraction of air sampled was below the detection limit.

© 2016 American Association for Aerosol Research     

Packaging technology for improving shelf‐life of fruits based on a nanoporous–crystalline polymer

The ability of films with an active layer of nanoporous–crystalline syndiotactic polystyrene (s‐PS) to prolong shelf‐life, not only of climacteric but also of non‐climacteric fruits, is discussed. Studies on oxygen and carbon dioxide concentrations in the environment of packaged fruits as well as in s‐PS active layers have been combined. Reported results indicate that prolonged shelf‐life can be associated with large increases and decreases of carbon dioxide and oxygen concentrations inside the package, respectively. These data are consistent with a higher barrier offered to both gases by nanoporous–crystalline s‐PS layers. This barrier phenomenon is due to reduction of gas diffusivity typical of nanoporous–crystalline polymer films, which is further enhanced by orientation, parallel to the film plane, of crystalline planes of closely packed s‐PS helices. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46256.     

Solution structure of human corticotropin releasing factor by 1H NMR and distance geometry with restrained molecular dynamics

The structure of human corticotropin releasing factor (hCRF)has been determined by proton nuclear magnetic resonance (¹HNMR) in a mixed-solvent system of 66% trifluoroethanol/34% H₂Oat pH 3.8 and 37°C. Nearly complete resonance assignmentwas achieved by using standard two-dimensional methods. Distancerestraints for structure calculations were obtained by qualitativeanalysis of intra- and interresidue nuclear Overhauser effects.Structures were obtained from the distance restraints by distancegeometry, followed by refinement using molecular dynamics andwere completed with amide hydrogen exchange data. The structureof hCRF in this solvent comprises an extended N-terminal tetrapeptideconnected to a well-defined -helix between residues 6 and 36.The first half of the -helix (residues 6–20) is clearlyamphipathic. The five carboxy-terminal residues are predominantlydisordered.     

The Effects of Electronic Impurities and Electron–Hole Recombination Dynamics on Large‐Grain Organic–Inorganic Perovskite Photovoltaic Efficiencies

Hybrid organic‐inorganic perovskites have attracted considerable attention after promising developments in energy harvesting and other optoelectronic applications. However, further optimization will require a deeper understanding of the intrinsic photophysics of materials with relevant structural characteristics. Here, the dynamics of photoexcited charge carriers in large‐area grain organic‐inorganic perovskite thin films is investigated via confocal time‐resolved photoluminescence spectroscopy. It is found that the bimolecular recombination of free charges is the dominant decay mechanism at excitation densities relevant for photovoltaic applications. Bimolecular coefficients are found to be on the order of 10^?9 cm³ s^?1, comparable to typical direct‐gap semiconductors, yet significantly smaller than theoretically expected. It is also demonstrated that there is no degradation in carrier transport in these thin films due to electronic impurities. Suppressed electron–hole recombination and transport that is not limited by deep level defects provide a microscopic model for the superior performance of large‐area grain hybrid perovskites for photovoltaic applications.     

Stability Study of a Mixed Islanded Power Network

This paper presents the modelling, simulation and analysis of the dynamic behaviour of a mixed power network of 2.78 GW including hydro, thermal and wind power plants. The modelling of each power plant is described. The set of parameters of the turbine speed governor of the hydroelectric power plant is determined with a specific identification procedure to achieve stable operation for different cases such as interconnected, isolated or islanded operation. The analysis of the stability of the entire mixed islanded power plant is investigated through time domain simulations for different sets of controllers parameters and for different disturbances （load rejection and turbulent wind speed profile）.     

Flowering as the Most Highly Sensitive Period of Grapevine (Vitis vinifera L. cv Mourvèdre) to the Botryosphaeria Dieback Agents Neofusicoccum parvum and Diplodia seriata Infection

Botryosphaeria dieback is a fungal grapevine trunk disease that currently represents a threat for viticulture worldwide because of the important economical losses due to reduced yield of affected plants and their premature death. Neofusicoccum parvum and Diplodia seriata are among the causal agents. Vine green stems were artificially infected with N. parvum or D. seriata at the onset of three different phenological stages (G stage (separated clusters), flowering and veraison). Highest mean lesion lengths were recorded at flowering. Major proteome changes associated to artificial infections during the three different phenological stages were also reported using two dimensional gel electrophoresis (2D)-based analysis. Twenty (G stage), 15 (flowering) and 13 (veraison) differentially expressed protein spots were subjected to nanoLC-MS/MS and a total of 247, 54 and 25 proteins were respectively identified. At flowering, a weaker response to the infection was likely activated as compared to the other stages, and some defense-related proteins were even down regulated (e.g., superoxide dismutase, major latex-like protein, and pathogenesis related protein 10). Globally, the flowering period seemed to represent the period of highest sensitivity of grapevine to Botryosphaeria dieback agent infection, possibly being related to the high metabolic activity in the inflorescences.     

The Stroop and Reverse Stroop Effects as Measured by an Interactive Tabletop

An interactive tabletop equipped with RFID technology implemented the Stroop and reverse-Stroop tasks. Participants moved a tangible object into one of four displayed virtual zones, which were identified either by a color border or the name of a color written in black. The correct target zone corresponded either to the color (Stroop) or meaning (reverse Stroop) of a word displayed in congruent or incongruent colored LED lights (e.g., “YELLOW” displayed in yellow or red, respectively). Participants took more time to place the object in a zone, made more errors, and found the task more difficult when the word was lit with an incongruent than congruent color. This interference was influenced by both the types of task and response zone in a way that fits with a dual step processing account. Results also showed that the outcomes of the conflicting information streams might be judged as fun.