A numerical study on the performance evaluation of ventilation systems for indoor radon reduction

Numerical simulations were conducted using computational fluid dynamics to evaluate the effect of ventilation conditions on radon (²²²Rn) reduction performance in a residential building. The results indicate that at the same ventilation rate, a mechanical ventilation system is more effective in reducing indoor radon than a natural ventilation system. For the same ventilation type, the indoor radon concentration decreases as the ventilation rate increases. When the air change per hour (ACH) was 1, the indoor radon concentration was maintained at less than 100 Bq/m³. However, when the ACH was lowered to 0.01, the average indoor radon concentration in several rooms exceeded 148 Bq/m³. The angle of the inflow air was found to affect the indoor air stream and consequently the distribution of the radon concentration. Even when the ACH was 1, the radon concentrations of some areas were higher than 100 Bq/m³ for inflow air angles of 5° and 175°.     

Fe-doped LaCoO<Subscript>3</Subscript> perovskite catalyst for NO oxidation in the post-treatment of marine diesel engine’s exhaust emissions

New post-treatment process for marine diesel engine exhaust emissions was proposed by combining NO oxidation and wet scrubbing technology for the simultaneous removal of SO_X, NO_X and PM. NO, insoluble in aqueous scrubbing absorbent, is preferentially oxidized to NO₂, which then turns fully soluble in it. Fe substituted LaCo_1-xFe_xO₃ perovskite catalysts were developed for NO oxidation to NO₂. The catalysts were prepared by co-precipitation method and analyzed with XRD, XRF, BET, FT-IR, NO-TPD and XPS techniques. Crystal structure change from rhombohedral to orthorhombic was observed with the increased amount of Fe substituted in the B site of the perovskite by XRD analysis. From FT-IR and NO-TPD analysis, nitrate on perovskite species was found to be the active species for NO oxidation. Quantitative analysis was performed within the prepared catalysts. Catalytic activity was measured using a packed bed reactor operated at 150–400 °C, atmospheric pressure and with gas hourly space velocity (GHSV) of 20,000 h^-1 using a simulated exhaust gas composed of NO 400 ppm, O₂ 10% balanced with N2. Formation of Fe⁴⁺ cation enhanced the redox property as well as the mobility of the lattice oxygen present in the perovskite catalysts, confirmed by XPS analysis. Reaction mechanism of NO oxidation on Fe substituted LaCo_1-xFe_xO₃ was discussed based on Mars-van Krevelen mechanism.     

Nb modified structural,magnetic and magnetocaloric properties of double perovskite Ba2FeMo1−xNbxO6

A systematic study focusing on the effect of Niobium (Nb) doping on the structural, magnetic and magnetocaloric properties of Ba₂FeMoO₆ samples is presented here. The samples of interest Ba₂FeMo_1?xNb_xO₆ (0 ≤ x ≤ 0.4) were prepared using the solid state reaction method and were confirmed to possess a cubic structure with Fm-3m space group using the X-ray diffraction analysis and Rietveld refinement. A second order of ferromagnetic phase transition was recorded in both the pure as well as the Nb doped samples using the temperature dependent magnetization and Arrott plots analysis. The pristine Ba₂FeMoO₆ (BFMO) sample indicated a spontaneous magnetization (34.6 emu/g at 100 K) with a relatively sharp magnetic transition at the Curie temperature (T_C) of 315 K as compared to the doped samples. A magnetic entropy change of 0.93 Jkg^?1K^?1 at an applied magnetic field of 2.5 T was measured for the pure BFMO sample. The doped BFMO samples with Mo partially substituted by Nb however, were observed to effectively modify the T_C accompanied by a decrease in magnetization. The results investigated in this work suggest that the magnetic and magnetocaloric properties of the BFMO can be tailored by controlled Nb doping which is of significant importance in order to realize the numerous potential applications of the material in the magnetic refrigeration technology.     

Preparation and characterizations of interpenetrating polymer network hydrogels of poly(ethylene oxide) and poly(methyl methacrylate)

Interpenetrating polymer network (IPN) hydrogels based on poly(ethylene oxide) and poly(methyl methacrylate) were prepared by radical polymerization using 2,2‐dimethyl‐2‐phenylacetophenone and ethylene glycol dimethacrylate as initiators and crosslinkers, respectively. The IPN hydrogels were analyzed for sorption behavior at 25°C and at a relative humidity of 95% using dynamic vapor sorption. The IPN hydrogels exhibited a relatively high equilibrium water content in the range of 13–68%. The state of water in the swollen IPN hydrogels was investigated using differential scanning calorimetry. The free water in the hydrogels increased as the hydrophilic content increased. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 258–262, 2003     

Antimicrobial activity of a monomer and its polymer based on quinolone

An acryl monomer containing the quinolone moiety was synthesized and then polymerized with azobisisobutyronitrile in a dimethylformamide solution. The resulting polymer as well as the corresponding monomer exhibited an excellent antibacterial activity. The poly(acrylated quinolone) (PQ) was compounded with other ordinary synthetic polymers such as low‐density polyethylene (LDPE), poly(butylene succinate) (PBS), poly(methyl methacrylate) (PMMA), maleated polypropylene (PPMA), and polycaprolactone (PCL). The polymer blends reduced the viable cell number significantly on contact during the shake flask test even when the PQ content was as low as 1 wt %. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1797–1801, 2003     

Ethylene polymerization over MgO‐supported zirconocene catalysts

Supported zirconcene catalysts on a new support, MgO, were prepared and tested in ethylene polymerization. Three types of impregnation methods were employed to find an optimum supporting method for MgO. The direct impregnation of Cp₂ZrCl₂ on MgO showed low metal loading and polymerization activity, while the catalyst had a higher metal loading and polymerization activity when MgO was treated with methylaluminoxane (MAO) before supporting. Treatment of MgO with MAO during the supporting step invoked two types of catalytic sites, which was evidenced by the bimodal molecular weight distribution of the polymer products. MgO is considered to have potential as a support for metallocenes.     

Meeting the challenge of water sustainability: The role of process systems engineering

This white paper is the result of discussions during the FIPSE-4 conference ( http://fi-in-pse.org ) in June 2018. It aims to highlight open problems and provide directions for future research in the area of water with emphasis on its agricultural usages. Some of the open problems discussed are: (a) the use of ecosystems as unit operations to understand their role in providing freshwater and in cleaning polluted water; (b) consideration of interactions and independencies between flows of water and other resources, such as food, energy, materials, ecosystem services, and environmental emissions; (c) challenges in modeling, sensing, and closed-loop control in precision irrigation. In particular, the development of agro-hydrological models that balance computing speed versus solution details and accuracy: (d) The use of state and parameter estimation approaches, through field measurements, to obtain soil moisture levels accurately; and (e) decision support systems to administer water and nutrient needs for optimum yields of agricultural products.     

Comparison of liquid-phase and methanol-swelling crosslinking processes of polyimide dense membrane for CO2/CH4 separation

To overcome the plasticization effect in polyimide membranes, many researchers have proposed crosslinking method. This can reduce an inter-segmental mobility by tightening and rigidifying the polymer chains. However, it is difficult to modify the whole polymer chains throughout the membrane because the reaction can be hindered by the diffusion rate of the crosslinker. In particular, it is hard for bulky crosslinker to penetrate a dense membrane with a small d-spacing. This study investigated the effect of crosslinking a dense Matrimid membrane with p-phenylenediamine (p-PDA) via two different crosslinking methods (i.e., methanol-swelling crosslinking process [M-SCP] and liquid-phase crosslinking process [L-PCP]). Most of the crosslinking reaction in M-SCP occurs on the membrane surface due to difficulty in penetration of the bulky p-PDA into the Matrimid dense membrane. In contrast, the L-PCP allows uniform crosslinking across the membrane. The membranes crosslinked using L-PCP showed excellent chemical resistance. Furthermore, the plasticization phenomenon was not observed in the membranes crosslinked using L-PCP with p-PDA more than 15%. Meanwhile, the membrane crosslinked using M-SCP exhibited poor plasticization and chemical resistance properties. These results showed that the L-PCP method can be more effective for the crosslinking of dense membrane to deliver both high plasticization and chemical resistance.     

Toll-Like Receptors: Expression and Roles in Otitis Media

Otitis media is mainly caused by upper respiratory tract infection and eustachian tube dysfunction. If external upper respiratory tract infection is not detected early in the middle ear, or an appropriate immune response does not occur, otitis media can become a chronic state or complications may occur. Therefore, given the important role of Toll-like receptors (TLRs) in the early response to external antigens, we surveyed the role of TLRs in otitis media. To summarize the role of TLR in otitis media, we reviewed articles on the expression of TLRs in acute otitis media (AOM), otitis media with effusion (OME), chronic otitis media (COM) with cholesteatoma, and COM without cholesteatoma. Many studies showed that TLRs 1–10 are expressed in AOM, OME, COM with cholesteatoma, and COM without cholesteatoma. TLR expression in the normal middle ear mucosa is absent or weak, but is increased in inflammatory fluid of AOM, effusion of OME, and granulation tissue and cholesteatoma of COM. In addition, TLRs show increased or decreased expression depending on the presence or absence of bacteria, recurrence of disease, tissue type, and repeated surgery. In conclusion, expression of TLRs is associated with otitis media. Inappropriate TLR expression, or delayed or absent induction, are associated with the occurrence, recurrence, chronicization, and complications of otitis media. Therefore, TLRs are very important in otitis media and closely related to its etiology.