Chemical composition of outdoor airborne particles at urban schools and possible implications for the air quality in classrooms

Vehicle emissions are a significant source of fine particles (Dp < 2.5 µm) in an urban environment. These fine particles have been shown to have detrimental health effects, with children thought to be more susceptible. Vehicle emissions are mainly carbonaceous in nature, and carbonaceous aerosols can be defined as either elemental carbon (EC) or organic carbon (OC). EC is a soot-like material emitted from primary sources while OC fraction is a complex mixture of hundreds of organic compounds from either primary or secondary sources (Cao et al., 2006). Therefore the ratio of OC/EC can aid in the identification of source. The purpose of this paper is to use the concentration of OC and EC in fine particles to determine the levels of vehicle emissions in schools. It is expected that this will improve the understanding of the potential exposure of children in a school environment to vehicle emissions

Re-Entry Aeroheating Analysis of Tile-Repair Augers for the Shuttle Orbiter

Computational re-entry aerothermodynamic analysis of the Space Shuttle Orbiter s tile overlay repair (TOR) sub-assembly is presented. Entry aeroheating analyses are conducted to characterize the aerothermodynamic environment of the TOR and to provide necessary inputs for future TOR thermal and structural analyses. The TOR sub-assembly consists of a thin plate and several augers and spacers that serve as the TOR fasteners. For the computational analysis, the Langley Aerothermodynamic Upwind Relaxation Algorithm (LAURA) is used. A 5-species non-equilibrium chemistry model with a finite rate catalytic recombination model and a radiation equilibrium wall condition are used. It is assumed that wall properties are the same as reaction cured glass (RCG) properties with a surface emissivity of epsilon = 0.89. Surface heat transfer rates for the TOR and tile repair augers (TRA) are computed at a STS-107 trajectory point corresponding to Mach 18 free stream conditions. Computational results show that the average heating bump factor (BF), which is a ratio of local heat transfer rate to a design reference point located at the damage site, for the auger head alone is about 1.9. It is also shown that the average BF for the combined auger and washer heads is about 2.0

Towards an evidence-based probabilistic risk model for ship-grounding accidents

AbstractMost of the risk models for ship-grounding accidents do not fully utilize available evidence, since it is based on accident statistics and expert opinions. The major issue with such kinds of models is their limitation in supporting the process of risk-management with respect to grounding accidents, since they do not reflect the reality to the extent required. This paper presents an evidence-based and expert-supported approach to structure a model assessing the probability of ship-grounding accidents, to make it more suitable for risk-management purposes. The approach focuses on using evidential data of ship-grounding accidents extracted from the actual accident and incident reports as well as the judgement elicited from the experts regarding the links and probabilities not supported by the reports. The developed probabilistic model gathers, in a causal fashion, the evidential contributing factors in ship-grounding accidents. The outcome of the model is the probability of a ship-grounding accident given the prior and posterior probabilities of the contributing factors. Moreover, the uncertainties associated with the elements of the model are clearly communicated to the end-user adopting a concept of strength-of-knowledge. The model can be used to suggest proper risk-control-measures to mitigate the risk. By running uncertainty and sensitivity analyses of the model, the areas that need more research for making educated decisions are defined. The model suggests the high-level critical parameters that need proper control measures are complexity of waterways, traffic situations encountered, and off-coursed ships. The critical area that calls for more investigation is the onboard presence of a sea-pilot

Knowledge and Attitude Level of Students about Solid Waste Recycling; Kashan University of Medical Sciences

Abstract Aims: Increasing of the population and development of urban areas, has led to solid waste generation increasing which is one of the problems and difficulties that put human and environmental health in danger. The aim of present study was to determine the knowledge and attitude level of Kashan University of Medical Sciences&rsquo; students about solid waste recycling. Instrument &amp; Methods: This cross-sectional study was carried out in the fall of 2012 at the Kashan University of Medical Sciences and all the 250 students studying at nursing, medical, and paramedical schools were participated in it. A researcher-made questionnaire consisting of 20 questions was used to determine the knowledge about and attitude toward solid waste recycling. Data was analyzed by ANOVA, Pearson correlation and independent T test. Findings: The knowledge of students was the highest about the definition of recycling (84.4) and lowest about delivery of recycled materials to badgers (23.6). Most medical (55.1) and paramedical (75.3) students had &ldquo;weak&rdquo; and most nursing students (47.1) had &ldquo;moderate&rdquo; knowledge about solid waste recycling. 69.2 of paramedical, 27.3 of medical and 25.5 of nursing students stated that &ldquo;there is no information about recycling in the university courses&rdquo;. Conclusion: Most of the students of Kashan University of Medical Sciences have weak knowledge regarding to solid waste recycling and their knowledge are different among schools

Two-sided asymmetric subduction; implications for tectonomagmatic and metallogenic evolution of the Lut Block, Eastern Iran

West directed subduction zones show common characteristics, such as low structural elevation, deep trench, steep slab and a conjugate back-arc basin that are opposite to those of the east directed subduction zones. The tectonomagmatic and metallogenic setting of the Lut Block is still a matter of debate and several hypotheses have been put forward. Despite some authors denying the influence of the operation of Benioff planes, the majority propose that it occurred beneath the Afghan Block, while others consider that oceanic lithosphere was dragged under the Lut Block. Cu-Au porphyry deposits seem to occur in an island arc geotectonic setting during the middle Eocene while Mo-bearing deposits are coincident with the crustal thickening during Oligocene. We introduce new trace element and isotope geochemical data for granitoids and structural evidences testifying the two-sided asymmetric subduction beneath both Afghan and Lut Blocks, with different rates of consumption of oceanic lithosphere

A Study of Ablation-Flowfield Coupling Relevant to the Orion Heatshield

The coupled interaction between an ablating surface and the surrounding aerothermal environment is studied. An equilibrium ablation model is coupled to the LAURA flowfield solver, which allows the char ablation rate (m-dot(sub c)) to be computed as part of the flowfield solution. The wall temperature (T(sub w)) and pyrolysis ablation rate (m-dot(sub g)) may be specified by the user, obtained from the steady-state ablation approximation, or computed from a a material response code. A 32 species thermochemical nonequilibrium flowfield model is applied, which permits the treatment of C, H, O, N, and Si containing species. Coupled ablation cases relevant to the Orion heatshield are studied. These consist of diffusion-limited oxidation cases with Avcoat as the ablation material. The m-dot(sub c) values predicted from the developed coupled ablation analysis were compared with those obtained from a typical uncoupled ablation analysis. The coupled results were found to be as much as 50% greater than the uncoupled values. This is shown to be a result of the cumulative effect of the two fundamental approximations inherent in the uncoupled analysis

COMPARATIVE STUDY OF EXHAUSTION AND PAD-STEAM METHODS FOR IMPROVEMENT OF HANDLE, DYE UPTAKE AND WATER ABSORPTION OF POLYESTER/COTTON FABRIC

In this study, a pad-steam process for treatment of polyester/cotton fabric with sodium hydroxide is developed and the effects of process parameters on selected properties of the fabric are investigated. The results are compared with the conventional exhaustion process. Both processes improved the handle, dyeability and water absorption of the polyester/cotton fabric, but the pad-steam process has the advantages of less strength loss of the fibers, shorter treatment time, lower consumption of water and chemicals that make the process less hazardous to the environment

Peak alpha frequency as a candidate biomarker of pain sensitivity: the importance of distinguishing slow from slowing

The study by Valentini et al. (2022) observed that the peak alpha frequency (PAF) of participants became slower after they were exposed to painful, as well as non-painful but unpleasant stimuli. The authors interpreted this as a challenge to our previous studies which propose that the speed of resting PAF, independently of pain-induced changes to PAF, can be a reliable biomarker marker for gaging individual pain sensitivity. While investigations into the role that PAF plays in pain perception are timely, we have some concerns about the assumptions and methodology employed by Valentini et al. Moreover, we believe the authors here have also misrepresented some of our previous work. In the current commentary, we detail the critical differences between our respective studies, with the ultimate aim of guiding future investigations

Effect of parasite infection with Posthodiplostomum cuticola (Nordmann, 1832) on fish growth rate in Zaringol Stream in Golestan Province

This study investigated the effect of parasite infection with Posthodiplostomum cuticola on fish growth rate in Zaringol Stream in Golestan Province. A total number of 447 fish specimens (173 Capoeta capoeta gracilis, 111 Alburnoides eichwaldii, 131 Paracobitis malapterura, 32 Neogobius fluviatilis) were captured by electrofishing during December 2009 to September 2010. Total number of parasite on fish body was counted by investigating internal organ and surface of skin and branch. Results showed that slope of regression curves and condition factor were significantly lower in infected C. c. gracilis. N. fluviatilis was the most abundant infected fish in Zarringol Stream. It seems that it's feeding dependence on benthos makes this fish more susceptible to infection by parasite