Emissions of Volatile Organic Compounds Inferred From Airborne Flux Measurements over a Megacity

Toluene and benzene are used for assessing the ability to measure disjunct eddy covariance (DEC) fluxes of Volatile Organic Compounds (VOC) using Proton Transfer Reaction Mass Spectrometry (PTR-MS) on aircraft. Statistically significant correlation between vertical wind speed and mixing ratios suggests that airborne VOC eddy covariance (EC) flux measurements using PTR-MS are feasible. City-median midday toluene and benzene fluxes are calculated to be on the order of 14.1±4.0 mg/m<sup>2</sup>/h and 4.7±2.3 mg/m<sup>2</sup>/h, respectively. For comparison the adjusted CAM2004 emission inventory estimates toluene fluxes of 10 mg/m<sup>2</sup>/h along the footprint of the flight-track. Wavelet analysis of instantaneous toluene and benzene measurements during city overpasses is tested as a tool to assess surface emission heterogeneity. High toluene to benzene flux ratios above an industrial district (e.g. 10–15 g/g) including the International airport (e.g. 3–5 g/g) and a mean flux (concentration) ratio of 3.2±0.5 g/g (3.9±0.3 g/g) across Mexico City indicate that evaporative fuel and industrial emissions play an important role for the prevalence of aromatic compounds. Based on a tracer model, which was constrained by BTEX (BTEX– Benzene/Toluene/Ethylbenzene/m, p, o-Xylenes) compound concentration ratios, the fuel marker methyl-tertiary-butyl-ether (MTBE) and the biomass burning marker acetonitrile (CH<sub>3</sub>CN), we show that a combination of industrial, evaporative fuel, and exhaust emissions account for >87% of all BTEX sources. Our observations suggest that biomass burning emissions play a minor role for the abundance of BTEX compounds in the MCMA (2–13%)

The Applicability of Taylor’s Model to the Drilling of CFRP Using Uncoated WC-Co Tools: The Influence of Cutting Speed on Tool Wear

This work investigates the applicability of Taylor’s model on the drilling of CFRP using uncoated WC-Co tools, by assessing the influence of cutting speed (Vc) on tool wear. Two different resins, possessing low and high glass transition temperatures (Tg), and two different reinforcements, high strength and high modulus woven fabrics, were combined into three different systems. Flank wear rate gradient exhibited to be more reinforcement dependent, while the actual flank wear rate showed to be sensible also to the type of resin. In terms of tool life, all CFRP systems adjusted into a power-type tool life vs. cutting speed curve through the full range of cutting speeds (1,000 RPM to 18,000 RPM). Therefore, Taylor’s model can be applied to estimate the tool life in the drilling of CFRP using uncoated WC-Co tools with good accuracy

Raising security awareness using cybersecurity challenges in embedded programming courses

Security bugs are errors in code that, when exploited, can lead to serious software vulnerabilities. These bugs could allow an attacker to take over an application and steal information. One of the ways to address this issue is by means of awareness training. The Sifu platform was developed in the industry, for the industry, with the aim to raise software developers' awareness of secure coding. This paper extends the Sifu platform with three challenges that specifically address embedded programming courses, and describes how to implement these challenges, while also evaluating the usefulness of these challenges to raise security awareness in an academic setting. Our work presents technical details on the detection mechanisms for software vulnerabilities and gives practical advice on how to implement them. The evaluation of the challenges is performed through two trial runs with a total of 16 participants. Our preliminary results show that the challenges are suitable for academia, and can even potentially be included in official teaching curricula. One major finding is an indicator of the lack of awareness of secure coding by undergraduates. Finally, we compare our results with previous work done in the industry and extract advice for practitioners.info:eu-repo/semantics/acceptedVersio

Anaplasma phagocytophilum in White-tailed Deer

We examined the reservoir potential of white-tailed deer for Anaplasma phagocytophilum. Results suggest that white-tailed deer harbor a variant strain not associated with human infection, but contrary to published reports, white-tailed deer are not a reservoir for strains that cause human disease. These results will affect surveillance studies of vector and reservoir populations

Applicability and sensitivity of PCR-SSCP method for milk species identification in cheese

Species identification in food has become a prominent issue in recent years as the importance of consumer protection has increased. DNA-based species identification methods were developed by researchers in the last two decades, as these are reliable, accurate, and low-cost techniques for species identification in raw and processed food products as well. In our study, universal primers were designed to conserved regions of mitochondrial 12S rRNA. Amplicons were heat-denatured and a PCR single strand conformation polymorphism (SSCP) method was developed to identify cattle, buffalo, sheep, and goat DNA. Sensitivity of this technique was tested on DNA mixtures of cattle-sheep, cattle-goat, and cattle-buffalo and the threshold limit of cattle DNA was 5%, 5%, and 3%, respectively. One hundred and five cheeses were purchased and collected from Bosnian and Hungarian farmers, retails, and supermarkets to reveal fraud, 32 percent of them (34 cheeses) were found to be mislabelled by species

Accelerated neuronal and synaptic maturation by BrainPhys medium increases Aβ secretion and alters Aβ peptide ratios from iPSC-derived cortical neurons

One of the neuropathological hallmarks of Alzheimer’s disease (AD) is cerebral deposition of amyloid plaques composed of amyloid β (Aβ) peptides and the cerebrospinal fluid concentrations of those peptides are used as a biomarker for AD. Mature induced pluripotent stem cell (iPSC)-derived cortical neurons secrete Aβ peptides in ratios comparable to those secreted to cerebrospinal fluid in human, however the protocol to achieve mature neurons is time consuming. In this study, we investigated if differentiation of neuroprogenitor cells (NPCs) in BrainPhys medium, previously reported to enhance synaptic function of neurons in culture, would accelerate neuronal maturation and, thus increase Aβ secretion as compared to the conventional neural maintenance medium. We found that NPCs cultured in BrainPhys displayed increased expression of markers for cortical deep-layer neurons, increased synaptic maturation and number of astroglial cells. This accelerated neuronal maturation was accompanied by increased APP processing, resulting in increased secretion of Aβ peptides and an increased Aβ38 to Aβ40 and Aβ42 ratio. However, during long-term culturing in BrainPhys, non-neuronal cells appeared and eventually took over the cultures. Taken together, BrainPhys culturing accelerated neuronal maturation and increased Aβ secretion from iPSC-derived cortical neurons, but changed the cellular composition of the cultures

On the temperatures developed in CFRP drilling using uncoated WC-Co tools Part II: Nanomechanical study of thermally aged CFRP composites

Abstract This study focused on the thermal degradation of the polymer phase of carbon fibre reinforced polymer (CFRP) composites through thickness by applying the nanoindentation technique. The results were compared for the elastic modulus (E) and hardness (H) of a non-aged sample and the samples aged at 200 °C and 350 °C during a short period of 60 s, in order to experimentally simulate the thermal conditions of drilling. Compared to the non-aged specimen, the results showed an increase of 16% in the elastic modulus and 12% in the hardness for the specimen aged at 200 °C. In contrast, the results for the specimen aged at 350 °C showed a variation of 0.8% and −3% in the elastic modulus and hardness respectively. These results contribute to a better understanding of the effect of the heat developed during the machining of composites on the properties of the resin phase in CFRP. Hereby we present the evidence of a post-curing effect at the temperatures close to the glass transition temperature (Tg) in the drilling of CFRPs

Explicit modeling of organic chemistry and secondary organic aerosol partitioning for Mexico City and its outflow plume

The evolution of organic aerosols (OA) in Mexico City and its outflow is investigated with the nearly explicit gas phase photochemistry model GECKO-A (Generator of Explicit Chemistry and Kinetics of Organics in the Atmosphere), wherein precursor hydrocarbons are oxidized to numerous intermediate species for which vapor pressures are computed and used to determine gas/particle partitioning in a chemical box model. Precursor emissions included observed C3-10 alkanes, alkenes, and light aromatics, as well as larger <i>n</i>-alkanes (up to C25) not directly observed but estimated by scaling to particulate emissions according to their volatility. Conditions were selected for comparison with observations made in March 2006 (MILAGRO). The model successfully reproduces the magnitude and diurnal shape for both primary (POA) and secondary (SOA) organic aerosols, with POA peaking in the early morning at 15–20 μg m<sup>−3</sup>, and SOA peaking at 10–15 μg m<sup>−3</sup> during mid-day. The majority (≥75%) of the model SOA stems from reaction products of the large <i>n</i>-alkanes, used here as surrogates for all emitted hydrocarbons of similar volatility, with the remaining SOA originating mostly from the light aromatics. Simulated OA elemental composition reproduces observed H/C and O/C ratios reasonably well, although modeled ratios develop more slowly than observations suggest. SOA chemical composition is initially dominated by δ-hydroxy ketones and nitrates from the large alkanes, with contributions from peroxy acyl nitrates and, at later times when NOx is lower, organic hydroperoxides. The simulated plume-integrated OA mass continues to increase for several days downwind despite dilution-induced particle evaporation, since oxidation chemistry leading to SOA formation remains strong. In this model, the plume SOA burden several days downwind exceeds that leaving the city by a factor of >3. These results suggest significant regional radiative impacts of SOA