Resistance of Geopolymer, Epoxy and Cement Mortar to Hydrocarbon-Based Synthetic Engine Lubricant, Hydraulic Fluid, Jet Fuel and Elevated Temperatures

Due to routine maintenance of aircraft on the concrete pavement at army airbases, a large part of the pavement surface is often found saturated with different hydrocarbon-based oil, fuel, and fluid. In addition, the pavement concrete is subjected to the aircraft’s exhaust temperature during operation. This study examined the resistance ability of 3 different cementitious materials: (i) epoxy, (ii) fly ash (FA) based geopolymer with various alkali to fly ash (AL/FA) ratios and (iii) Portland cement (PC) mortar under a simulated airfield circumstance. The mortar specimens were repetitively exposed to a mixture of synthetic engine oil, hydraulic fluids, jet fuel and elevated temperatures (175 °C) for 5 months simultaneously. During the exposures, geopolymer and PC mortar both suffered saponification. The degree of saponification of geopolymer samples is found to be highly reliant on the AL/FA ratios. On the contrary, the epoxy mortar was found to be resistant to saponification. It was also found that the PC mortar developed numerous thermal cracks but epoxy and geopolymer did not experience any visual thermal cracks under the same conditions

Proton exchange membrane fuel cells in electric vehicles: Innovations, challenges, and pathways to sustainability

Proton exchange membrane fuel cells are leading the shift to sustainable energy, especially in fuel-cell electric vehicles. In PEMFCs, hydrogen is converted into electricity which contributes to reduced greenhouse gas emissions and decreased dependence on fossil fuels. Many works have been conducted to improve the power density and longevity of the whole system to be adopted in vehicles. The power density was considerably increased by a stack design incorporating lightweight material such as graphene-coated Ni form and weak carbon nanofiber films. Hydrogen refueling failures such as overfilling with hydrogen, hydrogen flow overfill, and hydrogen leakage need mitigation by developing advanced materials and the improvement of refueling techniques. Hybrid Energy Storage Systems focus on combining technologies for storing electrical energy, structural and functional elements, and the optimization of ranges of power-management novel approaches and their principles. However, dynamic response performance, low-cost hydrogen refueling infrastructure, and diverse extensions with varying hydrogen capacity remain challenges. This article provides a comprehensive review of recent technological developments, policy frameworks, and energy sector developments for PEMFC applications in the automobile industry aiming to forecast recent achievements in the fields of PEMFC power management, cell structure, and optimization methodologies of power system energy

The Proportion of Periodontal Diseases among Type 2 Diabetes Mellitus Patients in a Selected Area of Dhaka, Bangladesh

This descriptive type of cross sectional study was conducted to find out the proportions of periodontal diseases among type 2 diabetes mellitus patients at National Healthcare Network (NHN) Mirpur Centre, Dhaka, Bangladesh using a pre-tested modified interviewer administrated semi structured questionnaire having purposively selected 120 samples. The study showed that 34.2% and 28.3% of the respondents were in the age group of 36 to 45 years and 46 to 55 years respectively with the mean age 46.95±10.31. Proportions of periodontitis were the highest approximately 56% followed by gingivitis was 32.5%. A highly significant association found between education level of the respondents and knowledge about cleaning teeth before going to bed and after breakfast (p=0.000). More than half of the respondents (55%) applied improper technique or method of tooth brushing followed by 39.2% applied mixed technique and the rest of 5.8% applied proper technique respectively. Although there was no significant relationship found between current smoker and periodontal diseases, chewing betel leaf was significantly associated with the occurrence of periodontal diseases (p=0.048). Multivariate logistic regression was also reveled this relationship. These periodontal diseases are multi-factorial diseases and the factors responsible for these diseases are preventable.DOI: http://doi.dx.org/10.3329/bjdre.v2i2.16242 Bangladesh Journal of Dental Research &amp; Education Vol.2(2) 2012: 36-41</jats:p

Resistance of Geopolymer, Epoxy and Cement Mortar to Hydrocarbon-Based Synthetic Engine Lubricant, Hydraulic Fluid, Jet Fuel and Elevated Temperatures

Due to routine maintenance of aircraft on the concrete pavement at army airbases, a large part of the pavement surface is often found saturated with different hydrocarbon-based oil, fuel, and fluid. In addition, the pavement concrete is subjected to the aircraft’s exhaust temperature during operation. This study examined the resistance ability of 3 different cementitious materials: (i) epoxy, (ii) fly ash (FA) based geopolymer with various alkali to fly ash (AL/FA) ratios and (iii) Portland cement (PC) mortar under a simulated airfield circumstance. The mortar specimens were repetitively exposed to a mixture of synthetic engine oil, hydraulic fluids, jet fuel and elevated temperatures (175 °C) for 5 months simultaneously. During the exposures, geopolymer and PC mortar both suffered saponification. The degree of saponification of geopolymer samples is found to be highly reliant on the AL/FA ratios. On the contrary, the epoxy mortar was found to be resistant to saponification. It was also found that the PC mortar developed numerous thermal cracks but epoxy and geopolymer did not experience any visual thermal cracks under the same conditions.</jats:p

Resistance of Geopolymer, Epoxy and Cement Mortar to Hydrocarbon-Based Synthetic Engine Lubricant, Hydraulic Fluid, Jet Fuel and Elevated Temperatures

Due to routine maintenance of aircraft on the concrete pavement at army airbases, a large part of the pavement surface is often found saturated with different hydrocarbon-based oil, fuel, and fluid. In addition, the pavement concrete is subjected to the aircraft&rsquo;s exhaust temperature during operation. This study examined the resistance ability of 3 different cementitious materials: (i) epoxy, (ii) fly ash (FA) based geopolymer with various alkali to fly ash (AL/FA) ratios and (iii) Portland cement (PC) mortar under a simulated airfield circumstance. The mortar specimens were repetitively exposed to a mixture of synthetic engine oil, hydraulic fluids, jet fuel and elevated temperatures (175 &deg;C) for 5 months simultaneously. During the exposures, geopolymer and PC mortar both suffered saponification. The degree of saponification of geopolymer samples is found to be highly reliant on the AL/FA ratios. On the contrary, the epoxy mortar was found to be resistant to saponification. It was also found that the PC mortar developed numerous thermal cracks but epoxy and geopolymer did not experience any visual thermal cracks under the same conditions

Clinicopathologic Findings from Autopsy of the first autopsy done for Patient with COVID-19, Sylhet

The China Health Authority alerted the World Health Organization (WHO) on December 31 2019, to several cases of pneumonia of unknown aetiology in Wuhan City in Hubei Province in central China. Since December 8, 2019, these cases had been reported, worked at or lived around the local Huanan Seafood Market. Radiology finding may vary with patients age, disease progression, immunity status, comorbidity, and initial medical intervention. In a study describing 41 of the initial cases of 2019-nCoV infection, all 41 patients had pneumonia with abnormal findings on chest computed tomography (CT-scan). Abnormalities on chest CT-scan were also seen in another study of 6 cases, in which all of them showed multifocal patchy ground-glass opacities notably nearby the peripheral sections of the lungs. Complete autopsy studies were almost nonexistent in the initial phases of the outbreak; reasonably so, due to concerns related to infectivity, transmission rates, and biosafety. The few reports initially published were limited to postmortem biopsies in COVID-19–positive patients or from lobectomy specimens initially resected for lung adenocarcinoma, but patients were later found to be COVID-19–positive (7). Pathologic features of exudative and proliferative phases of diffuse alveolar damage (DAD) were noted in these initial reports and overlapping features with SARS were also noted. Later complete autopsies performed in United States further supported the presence of DAD. The predominant pattern of lung lesions in COVID-19 patients is DAD, as described for the other two coronavirus that infect humans, SARS-CoV and MERSCoV. Hyaline membrane formation and pneumocyte atypical hyperplasia are frequently found. The main relevant finding is the presence of platelet-fibrin thrombi in small arterial vessels; this important observation fits into the clinical context of coagulopathy which dominates in these patients and which is one of the main targets of therapy. The macroscopic features of COVID-19 are likely to be in the chest and may include pleurisy, pericarditis, lung consolidation and pulmonary oedema. Lung weight may be increased above normal. It should be noted a secondary infection may be superimposed on the viral infection that can lead to purulent inflammation more typical of bacterial infection. The pulmonary histologic characteristics of COVID-19 resembled those observed in diseases caused by other Betacoronavirus infections such as severe acute respiratory syndrome4 and Middle East respiratory syndrome. Histopathology of the lungs showed diffuse alveolar damage, consistent with early acute respiratory distress syndrome in 8 cases. Predominant findings were hyaline membranes, activated pneumocytes, microvascular thromboemboli, capillary congestion, and proteinenriched interstitial edema. As described by Wang and colleagues, a moderate degree of inflammatory infiltrates concurred with clinically described leukopenia in patients with COVID-19 and predominant infiltration of lymphocytes fit the picture of a viral pathogenesis.</jats:p