Investigation of ambient aerosol effective density with and without using a catalytic stripper

Lin, Yue,Bahreini, Roya,Zimmerman, Stephen,Fofie, Emmanuel A.,Asa-Awuku, Akua,Park, Kihong,Lee, Seung-Bok,Bae, Gwi-Nam,Jung, Heejung S. Elsevier 2018 Atmospheric environment Vol.187 No.-

<P><B>Abstract</B></P> <P>Size-resolved effective densities of ambient aerosols in Riverside, CA were determined over 4 periods during 2015–2016. A DMA-CPMA-CPC technique was used to measure effective density for particles with selected diameters of 50, 70, 101 and 152 nm. A catalytic stripper (CS) was used alternately to remove the volatile fraction of aerosol before density measurements. Aerosol non-refractory composition measurement was conducted in June 2016 campaign to understand the effect of chemical composition on particle density. The average densities for particles over all the measurement campaigns over BP mode (i.e. bypassing the CS) were 1.17 g/cm<SUP>3</SUP> at 50 nm and 1.25–1.28 g/cm<SUP>3</SUP> at 70, 101 and 152 nm. The average density after CS conditioning (CS mode) showed a decreasing trend from 1.22 g/cm<SUP>3</SUP> to 1.04 g/cm<SUP>3</SUP>, with increase in the selected size, and a mass fractal dimension (D<SUB>f</SUB>) of 2.85. Both the BP and CS mode particles showed the lowest effective density at 6–9 am and highest density at 11 a.m.-3 pm. The diurnal variation of density for both modes became more intensive as particle size increased. The variation was also more intense for the CS mode compared to the BP mode. Organic aerosol and ammonium nitrate mass in the size range of density measurements correlated well positively (R<SUP>2</SUP> = 0.78) and negatively (R<SUP>2</SUP> = 0.62), respectively with BP mode effective density. The study provides an update to the aerosol density profiles of a well-known receptor site (Riverside, CA) and investigates the transformation of particles in different seasons. The effective density profiles will be used in a follow-up study to better estimate the respiratory-deposited ambient aerosol mass.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Seasonal variation of ambient particle effective densities. </LI> <LI> Size dependent refractive particle effective densities. </LI> <LI> Influence of particle chemical composition on diurnal variation of particle effective density. </LI> </UL> </P>

Polyethersulfone/poly (butylene succinate) membrane: Effect of preparation conditions on properties and performance

Vahideh Ghaffarian,Seyed Mahmoud Mousavi,Maesumeh Bahreini,Hossein Jalaei 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.4

In this study, biodegradable polymer of poly (butylene succinate) (PBS) was blended with polyethersulfone (PES) to prepare a novel semi-biodegradable membrane. The effect of blend ratio and coagulation bath temperature (CBT) was investigated on membrane characteristics including membrane morphology, mechanical strength and also treatment ability. Moreover, Fourier transform infrared (FTIR) spectrum, thermal stability, biodegradation and contact angle of the membranes were studied. Results demonstrated that the wastewater permeation through the prepared membranes was increased by blending the polymers and reached to maximum at blend ratio of 50/50. The wastewater treatment of PES/PBS blend membranes was improved by increasing PBS content.

Static analysis of FGM cylinders by a mesh-free method

M. Foroutan,R. Moradi-Dastjerdi,R. Sotoodeh-Bahreini 국제구조공학회 2012 Steel and Composite Structures, An International J Vol.12 No.1

In this paper static analysis of FGM cylinders subjected to internal and external pressure was carried out by a mesh-free method. In this analysis MLS shape functions are used for approximation of displacement field in the weak form of equilibrium equation and essential boundary conditions are imposed by transformation method. Mechanical properties of cylinders were assumed to be variable in the radial direction. Two types of cylinders were analyzed in this work. At first cylinders with infinite length were considered and results obtained for these cylinders were compared with analytical solutions and a very good agreement was seen between them. Then the proposed mesh-free method was used for analysis of cylinders with finite length and two different types of boundary conditions. Results obtained from these analyses were compared with results of finite element analyses and a very good agreement was seen between them.

Use of membrane separation in enzymatic hydrolysis of waste paper

Narges Milani Rad,Seyed Mahmoud Mousavi,Masoumeh Bahreini,Ehsan Saljoughi 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.3

A three-stage process containing phosphoric acid pretreatment, enzymatic hydrolysis, and membrane filtration was performed on waste paper as a lignocellulosic material. In the first two stages, the effect of phosphoric acid concentration, enzyme loading, hydrolysis time, and substrate concentration on the amount of products was investigated. At the third stage using a proper membrane, the effect of substrate concentration and transmembrane pressure (TMP) on yield of the reducing sugars was studied. The novelty of the present study was to demonstrate the application of ultrafiltration membrane on the enzymatic hydrolysis process of waste paper. The reducing sugars concentration was determined by using the 3,5-dinitrosalicylic acid (DNS) reagent method. According to the results, a value of 0.5% was determined as the optimum concentration for phosphoric acid in the pretreatment stage. The reducing sugars yield was obtained as 67.4% in this concentration. Moreover, for the enzymatic hydrolysis of waste paper, the suitable amounts of cellulase enzyme loading and hydrolysis time were determined as 50 mg/g substrate and 48 h, respectively. In the filtration stage, increase of substrate concentration and decrease of TMP resulted in higher rejection of the reducing sugars. The experimental results revealed that the highest rejection was 19.2% at TMP of 3 bar and substrate concentration of 100 g/L.

PCR-based Identification of Aflatoxigenic Fungi Associated with Iranian Saffron

Reihaneh Noorbakhsh,Ahmad Reza Bahrami,Seyed Ali Mortazavi,Bita Forghani,Maesoomeh Bahreini 한국식품과학회 2009 Food Science and Biotechnology Vol.18 No.4

Aflatoxins are secondary metabolites produced by the aflatoxigenic fungi in suitable conditions. Saffron, Crocus sativus, is the most expensive spice in the world. Saffron is normally contaminated with soil and hand microflora during harvest and post-harvest operations. In this study, rapid assessment of aflatoxigenic fungi in saffron was accomplished using polymerase chain reaction. In total, 37 market samples were assayed in order to isolate aflatoxin-producing fungi. The 18.9% of the total samples were contaminated with aflatoxigenic fungi. Our results also show that most of the isolated fungi were saprophytes which are normally originated from soil during harvest and postharvest process.

Differentiation of adipose-derived stem cells into Schwann-like cells: fetal bovine serum or human serum?

Elham Younesi,Vahid Bayati,Mahmoud Hashemitabar,Seyyed Saeed Azandeh,Dariush Bijannejad,Amin Bahreini 대한해부학회 2015 Anatomy & Cell Biology Vol.48 No.3

Access to autologous Schwann cells is limited due to lack of donor site and its difficult isolation and culture. Therefore, one of the possible ways to obtain to Schwann cells is to differentiate mesenchymal stem cells into glial pathway using various materials and protocols. The aim of this study was to compare the effects of fetal bovine serum and human serum on Schwann cell differentiation of adipose-derived stem cells to choose the best serum for use in future research. For this purpose, after isolation of human adipose-derived stem cells, it was characterized and differentiated into Schwann cell lineage using two protocols which one of them contained fetal bovine serum and the other human serum. At the end, morphological evaluation declared an increased detachment of cells in response to human serum. On the other side, immunocytochemistry showed that there was a significant increase in the number of cells expressing glial fibrillary acidic proteins and S100 in fetal bovine serum-treated group when compared to human serum-treated one (P