Statistical Analysis of the Droplet Size Distribution of Tire Pyrolysis Oil-Diesel Oil Sprays

The liquid product obtained from tire pyrolysis process, called tire pyrolysis oil (TPO), has a great attraction as an alternative fuel, as it has a viscosity of 5.43 cSt (Sharma et al., 2016), density of 921 kg/m³ (Gamboa et al., 2020), surface tension of 0.028 N/m (Chumpitaz et al., 2019), and higher heating value of 46.32 MJ/kg (Das et al., 2017), which are similar to diesel oil. These physical and chemical properties have motivated research into its application in furnaces, boilers and compression ignition engines. Generally, TPO is blended with diesel or biodiesel in order to decrease the percentage of sulfur and improve the cetane number of the fuel blend (Sharma et al., 2016). However, the evaluation of the quality and applicability of TPO has been focused mainly on combustion emissions and the performance of thermal equipment fueled with this fuel (and diesel/biodiesel blends), where the atomization process has been ignored, which is closely linked with the efficiency of liquid fuel evaporation and combustion. Thus, in this work, an evaluation of the atomization quality of blends of tire pyrolysis oil and diesel oil was carried out based on the comparison of the uniformity parameters of the drop size distribution of fuel sprays. The distribution function used was the Log-Normal function, as it allowed reconstructing the droplet size distribution of the sprays with only the mass median diameter and Sauter mean diameter. These values were measured using the Malvern Spraytec laser diffraction system model STP5936 (Chumpitaz et al., 2019). The fuel sprays were generated with a twin-fluid atomizer (type Y-jet) operating at air-to-fuel mass ratio (RAL) in the range of 0.05 to 0.35. The results showed that the higher the percentage by mass of TPO in the fuel blend, the lower the uniformity of the spray. Furthermore, a uniform TPO-DO spray with smaller mean diameters (0.15) are applied and percentages of TPO in the blend less than 5% are used

Potential health impact of ultrafine particles under clean and polluted urban atmospheric conditions: a model-based study

The main goal of this study was to improve the knowledge of ultrafine particle number distributions in large urban areas and also to call the attention to the importance of these particles on assessing health risks. Measurements of aerosol size distributions were performed during 2 weeks, with distinct pollutant concentrations (polluted and clean periods), on the rooftop of a building located in downtown of the megacity of São Paulo, Brazil. CO, NO2, PM10, SO2, and O3 concentrations and meteorological variables were also used. Aerosol size distribution measurements showed that geometric mean diameters of the size spectra in the polluted period are on average considerably larger than those in the clean one. Besides the fact that total number of ultrafine particles did not show significant differences, during the polluted period, geometric mean diameter was larger than during the clean one. The results of a mathematical model of particle deposition on human respiratory tract indicated a more significant effect of smaller particles fraction of the spectra, which predominate under clean atmospheric conditions. The results also indicated that urban environmental conditions usually considered good for air quality, under the criteria of low mass concentration, do not properly serve as air quality standard to very small particles. In the size range of ultrafine particles, this traditional clean atmospheric condition can offer a strong risk to pulmonary hazards, since the cleansing of the atmosphere creates good conditions to increase the concentration of nucleation mode particles

Effects of Size Distributions From Two Distinct Polluted Environments On Dry Deposition of Atmospheric Aerosols

Um modelo matemático simples foi utilizado para estudar oefeito da distribuição de tamanho das partículas sobre a eficiência deremoção por deposição seca. Para esta finalidade foram utilizadas duasdistribuições de tamanho de aerossóis, típicas de ambientes poluídos:uma distribuição de ambiente de queimada (Amazônia) e outra de ambienteurbano (São Paulo). Os resultados mostraram que partículas origináriasde ambiente urbano são mais eficientemente removidas por deposiçãoseca do que partículas de queimada. Este comportamento está associadoao fato de que a natureza de remoção das partículas por deposiçãoseca é pouco eficiente para diâmetros entre 0,1 e 1,0 mm, domínioem que se concentra a maior parte das partículas de queimada. Esse mecanismodiferencial de deposição é o que explica o maior efeito deletériodas partículas ultra-finas no sistema respiratório humano

Variabilidade das Concentrações do o3 Troposférico: Dados de Superfície e Sondagens Medidos durante a Campanha Primavera de o3. Em 2006

Variabilidade das concentrações do O3 troposférico: dadosde superfície e sondagens medidos durante a campanha“Primavera de O3” em 200

HPA e Nitro-HPA em Ambiente Semifechado Impactado por Emissão da Combustão de Diesel/Biodiesel (B5)

In order to verify the presence of polycyclic aromatic hydrocarbons (PAHs) and nitro-PAH (NPAH) associated with the fine fraction of particulate matter (PM1.0 and PM2.5) from the combustion of diesel/biodiesel mixture (B5), daily samples were carried out in the urban bus station of Londrina. A high performance liquid chromatography with mass spectrometry (LC-APCI-MS) was used for the determination of nitro-PAH and the PAHs were determined by high performance liquid chromatography equipped with fluorescence detector (LC-FLD). 9 PAHs and 1-nitropyrene were determined. The concentrations of the PAHs with 4 to 6 rings (fluoranthene, pyrene, crysene, benzo(b)fluoranthene, benzo(k)fluoranthene and dibenzo(a,h)antharacene) were higher in comparison to the lighter PAHs (acenaphthene, fluorene and anthracene). The ∑PAH associated to the PM1.0 corresponded to 66% of the PM2.5 with concentrations that exceed the levels recommended by WHO. The diagnostic ratios (DR) of PAHs and NPAH were calculated and the results suggest diesel/biodiesel (B5) emissions. The use of biofuel in Brazil is encouraged and the monitoring of changes in emissions arising from combustion processes is important and necessary to follow the change of air quality and the impact on the environment.  DOI: http://dx.doi.org/10.17807/orbital.v7i3.73

Persistent symptoms and decreased health-related quality of life after symptomatic pediatric COVID-19: A prospective study in a Latin American tertiary hospital

OBJECTIVES: To prospectively evaluate demographic, anthropometric and health-related quality of life (HRQoL) in pediatric patients with laboratory-confirmed coronavirus disease 2019 (COVID-19) METHODS: This was a longitudinal observational study of surviving pediatric post-COVID-19 patients (n=53) and pediatric subjects without laboratory-confirmed COVID-19 included as controls (n=52) was performed. RESULTS: The median duration between COVID-19 diagnosis (n=53) and follow-up was 4.4 months (0.8-10.7). Twenty-three of 53 (43%) patients reported at least one persistent symptom at the longitudinal follow-up visit and 12/53 (23%) had long COVID-19, with at least one symptom lasting for >12 weeks. The most frequently reported symptoms at the longitudinal follow-up visit were headache (19%), severe recurrent headache (9%), tiredness (9%), dyspnea (8%), and concentration difficulty (4%). At the longitudinal follow-up visit, the frequencies of anemia (11% versus 0%, p=0.030), lymphopenia (42% versus 18%, p=0.020), C-reactive protein level of >30 mg/L (35% versus 0%, p=0.0001), and D-dimer level of >1000 ng/mL (43% versus 6%, p=0.0004) significantly reduced compared with baseline values. Chest X-ray abnormalities (11% versus 2%, p=0.178) and cardiac alterations on echocardiogram (33% versus 22%, p=0.462) were similar at both visits. Comparison of characteristic data between patients with COVID-19 at the longitudinal follow-up visit and controls showed similar age (p=0.962), proportion of male sex (p=0.907), ethnicity (p=0.566), family minimum monthly wage (p=0.664), body mass index (p=0.601), and pediatric pre-existing chronic conditions (p=1.000). The Pediatric Quality of Live Inventory 4.0 scores, median physical score (69 [0-100] versus 81 [34-100], p=0.012), and school score (60 [15-100] versus 70 [15-95], p=0.028) were significantly lower in pediatric patients with COVID-19 at the longitudinal follow-up visit than in controls. CONCLUSIONS: Pediatric patients with COVID-19 showed a longitudinal impact on HRQoL parameters, particularly in physical/school domains, reinforcing the need for a prospective multidisciplinary approach for these patients. These data highlight the importance of closer monitoring of children and adolescents by the clinical team after COVID-19

Highly Active Microbial Phosphoantigen Induces Rapid yet Sustained MEK/Erk- and PI-3K/Akt-Mediated Signal Transduction in Anti-Tumor Human γδ T-Cells

BACKGROUND: The unique responsiveness of Vgamma9Vdelta2 T-cells, the major gammadelta subset of human peripheral blood, to non-peptidic prenyl pyrophosphate antigens constitutes the basis of current gammadelta T-cell-based cancer immunotherapy strategies. However, the molecular mechanisms responsible for phosphoantigen-mediated activation of human gammadelta T-cells remain unclear. In particular, previous reports have described a very slow kinetics of activation of T-cell receptor (TCR)-associated signal transduction pathways by isopentenyl pyrophosphate and bromohydrin pyrophosphate, seemingly incompatible with direct binding of these antigens to the Vgamma9Vdelta2 TCR. Here we have studied the most potent natural phosphoantigen yet identified, (E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate (HMB-PP), produced by Eubacteria and Protozoa, and examined its gammadelta T-cell activation and anti-tumor properties. METHODOLOGY/PRINCIPAL FINDINGS: We have performed a comparative study between HMB-PP and the anti-CD3epsilon monoclonal antibody OKT3, used as a reference inducer of bona fide TCR signaling, and followed multiple cellular and molecular gammadelta T-cell activation events. We show that HMB-PP activates MEK/Erk and PI-3K/Akt pathways as rapidly as OKT3, and induces an almost identical transcriptional profile in Vgamma9(+) T-cells. Moreover, MEK/Erk and PI-3K/Akt activities are indispensable for the cellular effects of HMB-PP, including gammadelta T-cell activation, proliferation and anti-tumor cytotoxicity, which are also abolished upon antibody blockade of the Vgamma9(+) TCR Surprisingly, HMB-PP treatment does not induce down-modulation of surface TCR levels, and thereby sustains gammadelta T-cell activation upon re-stimulation. This ultimately translates in potent human gammadelta T-cell anti-tumor function both in vitro and in vivo upon transplantation of human leukemia cells into lymphopenic mice, CONCLUSIONS/SIGNIFICANCE: The development of efficient cancer immunotherapy strategies critically depends on our capacity to maximize anti-tumor effector T-cell responses. By characterizing the intracellular mechanisms of HMB-PP-mediated activation of the highly cytotoxic Vgamma9(+) T-cell subset, our data strongly support the usage of this microbial antigen in novel cancer clinical trials