A Laboratory Study of Low-Temperature CO Removal from Mobile Exhaust Gas Using In-Plasma Catalysis

The combination of nonthermal plasma (NTP) with catalytic methods has been shown to improve catalyst light-off temperature via reactions among plasma discharge products and by-products. Thus, NTP may improve selectivity, process, and removal efficiency. In this study, NTP was combined with a catalytic film of mixed metal oxides (ceria-zirconia-gamma alumina layer) in the discharge zone to investigate low-temperature CO removal. Three different reactors having identical geometries were used: a plasma reactor, a catalytic reactor, and a hybrid plasma-catalytic reactor. The CO removal efficiency of 36.5 was achieved using hybrid plasma-catalytic reactor at 80 °C with 860 J/lit. The temperature and flow rate were found to have significant impacts (P-value � 0.05), which is unexpected due to the key role of hydroxyl and active radicals induced by plasma discharge. Calculated synergy factor of about 2 signals call for further study on the hybrid properties of catalytic efficiency and plasma physics for optimal CO removal. © 2020, Springer Nature Switzerland AG

Conformational analysis and nonlinear optical properties of the N, N'-pentamethylenebis(salicylideneiminato)manganase(II) complex

Conformational analysis of the tricyclic Schiff base chelate complex N,N'-pentamethylenebis(salicylideneiminato)manganese(II) is performed by means of the molecular mechanic (MM+), semi-empirical PM3 and density functional (B3LYP/LanL2DZ) methods, respectively. Eight starting structures of the complex are minimized. The structures of the three lowest minimum energy conformations of cyclooctane, boat-chair (bc), chair-chair (cc) and boat-boat (bb), are used as initial approximations to the geometry of the eight-membered chelate ring. The absolute-MEC (Mn-bc4) and the most unstable one (Mn-bb) originate from the boat-chair-shaped form of the eight-membred cycle, differing in the position of the metal atom. After the conformational analysis of the tricyclic Schiff base chelate complex, nonlinear optical properties and optical band gap (E HOMO-LUMO) were calculated with B3LYP/LanL2DZ level of theory for all conformations. The frontier molecular orbital calculations clearly show the inverse relationship of optical band gap (E HOMO-LUMO) with the total static hyperpolarizability

The effect of different teaching methods to understanding of chemical equilibrium at micro level [Kimyasal denge konusunun mikro boyutta anlaşılmasına farklı öğretim yöntemlerinin etkisi1]

The aim of this study is to determine students’ understandings related to chemical equilibrium at micro level by using different teaching methods. It was used quasi-experimental method with pre-and posttest. The sample was comprised of 90 first class science teacher education program students. It was studied with three groups: cooperative learning group (student teams achievement divisions method, STAD) (CLG, N=22), cooperative-model group (STAD + models) (CMG, N=41) and control group (CG, N=27). In order to compare the groups it was used a multiple choices Particulate Nature of Matter Test (PNMTa) related to chemical equilibrium. The PNMTa consists of six questions. For determining students’ conceptual understandings related to the subject, the PNMTa was rearranged as open-ended with removing choices (PNMTb). According to ANOVA results, it was not found significant difference among groups. Also, according to open-ended question, it was determined some misconceptions related to topic. © 2017, Ankara University. All rights reserved

Occupational exposure of health care personnel to SARS-CoV-2 particles in the intensive care unit of Tehran hospital

The outbreak of SARS-CoV-2 (COVID-19) has attracted much attention to study its possible presence and airborne transmission. The possibility of COVID-19 airborne transmission in indoor environments is debatable. The present study examined the concentration of viral RNA-containing particles produced directly or indirectly by breathing or coughing of confirmed COVID-19 patients or by carriers without symptoms. Some studies do not accept this method of transmission (COVID-19 airborne transmission). The present study aimed to measure the possible exposure of health care personnel to SARS-CoV-2 particles that may have been suspended in the air to respond to the hypothesis of COVID-19 airborne transmission. Airborne particle sampling was performed using impingement method based on NIOSH (chapter BA) and ASHRAE. Selection of sampling sections was in line with the WHO guidelines. The samples were analyzed using RT-PCR technique. Based on the given results, airborne particles of COVID-19 may present in the air and affect the health of hospital personnel. In fact, the analysis of gene expression in ambient conditions and thereby aerosol transmission of SARS-CoV-2 through air is possible and may lead to occupational exposure of health care personnel. Furthermore, it was found that airborne emission of COVID-19 through the breathing zone of patients, particularly in ICU wards with confirmed cases of COVID-19, may be higher than in other ICU wards. Also, the demonstrated results showed that there is a possibility of reaerosolization (reintroduction) of previously airborne SARS-CoV-2 particles into the atmosphere due to health care personnel frequently walking between different wards and stations of ICU. © 2021, The Author(s)