AIM To examine two types of orthodontic separators, focusing on the separating effect and patients' perception of pain and discomfort. METHODS The separators tested were spring-type and elastomeric separators. Thirty teenagers participated, and all were scheduled for treatment with a fixed orthodontic appliance. Two spring-type and two elastomeric separators were placed alternately in the lef...

Air Pollution is one of the significant problems in Tehran. Understanding the role of different sources can result in better decision-making. Some pollutions are not emitted directly from sources and are present in the atmosphere due to chemical reactions. Therefore, using air quality modeling can be beneficial to our understanding of these phenomena. An air quality modeling system was used fir...

the wide availability of data on air pollutant emissions, the knowledge already achieved on theset of chemical and photochemical reactions in the troposphere, the ability to access real time weatherconditions at the local scale that determine the transport and transformation of gases and aerosol, now make it possible to obtain credible and reliable predictions, retrospective analyses and/or fut...

the main objective of a research program, whose output is presented here, has been to estimate “ventilation coefficients”, a critical parameter in determining air pollution concentration near the surface ground which signifies the ability for natural ventilation of an air shed in an urban or rural area. relevant measured data from the city of tehran has been used to calibrate and further de...

the wide availability of data on air pollutant emissions, the knowledge already achieved on theset of chemical and photochemical reactions in the troposphere, the ability to access real time weatherconditions at the local scale that determine the transport and transformation of gases and aerosol, now make it possible to obtain credible and reliable predictions, retrospective analyses and/or fut...

today, the cement industry is one of the major air polluting industries in the world. hence, in this study, owing to the importance and role of contaminants from the plant, an appraisal of the emission contributions in addition to other factors have been discussed. there are several reasons behind the importance of modeling air pollutants. first, the assessment of standards for air pollution, a...

The fructose/dioxygen biofuel cell, one of the direct electron transfer (DET)-type bioelectrochemical devices, utilizes fructose dehydrogenase (FDH) on the anode and multi-copper oxidase such as bilirubin oxidase (BOD) on the cathode as catalysts. The power density in the literature is limited by the biocathode performance. We show that the DET-type biocathode performance is greatly improved, w...

A shorter start-up time and highly negative anode potentials are needed to improve single-chamber air-cathode microbial fuel cells (MFCs). Using a glass fiber separator reduced the start-up time from 10d to 8d at 20°C, and from 4d to 2d at 30°C, and enhanced coulombic efficiency (CE) from <60% to 89% (20°C) and 87% (30°C). Separators also reduced anode potentials by 20-190mV, charge transfer re...

G. A. Dirac characterized chordal graphs as those in which minimal vertex separators always induce complete subgraphs. I generalize a traditional (2-)vertex separator to a k-vertex separator — meaning a set S of vertices whose removal puts k independent vertices into k separate components. Generalizing Dirac’s theorem, the {P5, 2P3}-free chordal graphs are the graphs in which minimal k-separato...