Effects of an external electric field on the collection efficiency of air filters: Filtration mechanisms with an external e-field

An external electric field was applied on the filter to improve its collection efficiency, and the collection efficiencies of the different filters under various conditions were evaluated. Dominant electrical filtration mechanisms for each condition were investigated using experimental and theoretical approaches. Four types of air filters were used as test filters: a charged fiber filter, a low-grade filter with 50% collection efficiency in the most penetration particle size (MPPS) zone, and two high-grade filters with more than 95% collection efficiency in the MPPS zone. Three different particle charge states—neutralized, single-charged and uncharged—were considered. For neutralized particles, the external electric field led to a 14.5%p. and 2.5%p. increase in the collection efficiencies of the low-grade filter and charged fiber filter, respectively. With the electric field, the collection efficiency of the low-grade filter increased by 30%p. for single-charged particles. The electric field also affected the collection efficiencies of the charged filter and high-grade filters, but the effect was not significant. For uncharged particles, the electric field did not lead to a remarkable increase in the collection efficiencies of any of the filters. Through experimental and theoretical analysis, it was found that the polarization force imposed on the charged fiber was the dominant factor for the charged fiber filter regardless of application of the external electric field. The Coulombic force imposed on the electric field was the dominant factor for the low-grade filter, while both the Coulombic and the polarization forces affected the collection efficiency of the high-grade filter.

Copyright © 2017 American Association for Aerosol Research     

Development of chitosan/Spirulina bio‐blend films and its biosorption potential for dyes

Chitosan/Spirulina bio‐blends (CSBB) in films form were developed to be an alternative/renewable biosorbent, able to remove anionic and cationic dyes from aqueous solutions. CSBB potential as biosorbent was investigated for cationic dye Methylene Blue (MB), and anionic dyes Tartrazine Yellow (TY) and Reactive Black 5 (RB5). Chitosan and Spirulina samples were obtained and characterized, and CSBB films were prepared with different chitosan/Spirulina ratios. The CSBB films characteristics, as, mechanical properties, thermal profile, crystallinity, functional groups, morphology, and biosorption potential were strongly dependent of chitosan/Spirulina ratio. CSBB films preserved its mechanical structures at pH from 4.0 to 8.0. The biosorption capacities were 120, 110, and 100 mg g^?1 for RB5, TY, and MB, respectively. The increase of chitosan amount favored the TY and RB5 biosorption; however, the increase of Spirulina amount favored the MB biosorption. Thus, the CSBB in film form is a renewable biosorbent suitable to remove anionic and cationic dyes from aqueous solutions. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44580.     

Systemized organic functional group controls in polydiacetylenes and their effects on color changes

A variety of organic functional groups have been successfully installed into polydiacetylenes (PDAs) and applied to the color change‐controlled system of PDA sensors. Ten diacetylene compounds possessing different functionalities and lengths were systemically synthesized and fully characterized using spectroscopic methods. The polymerized vesicle solution with these compounds showed different temperatures required to induce a color change (from blue to red) depending on the functionalities installed on 10,12‐pentacosadiynoic acid (PCDA) molecules. In addition, the results reported here reveal that the intermolecular interactions of PCDA molecules and the intermolecular distance play a key role to the color of PDA system. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45011.     

Fabrication of photochromic hydrogels using an interpenetrating chitosan network

The synthesis of a novel interpenetrating chitosan network post‐modified with spiropyran (SP) derivatives has been used to develop photochromic hydrogels. We have synthesized succinyl chitosan polymers containing a considerable number of both amines and carboxylic groups. Their intra/inter molecular amide coupling reactions and postmodification with SP derivatives resulted in the photochromic hydrogels functionalized with chitosan‐based interpenetrating polymer network structures. In this hydrogel system, SPs undergo reversible photoresponsive structural switching between a ring‐closed colorless SP form and a ring‐opened purple merocyanine form under specific light‐irradiation conditions. Notably, the photo‐mediated wettabilities and color intensities of the hydrogels increase by the increment in the molecular weight of SP‐functionalized chitosans. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45120.     

Rapid and efficient deoxygenation of sulfoxides to sulfides with tantalum(V) chloride/sodium iodide system

TaCl₅/NaI system converts a wide range of sulfoxides to the corresponding sulfides in high yields with short reaction times, under mild conditions. It is worth mentioning that this protocol is chemoselective and tolerates various functional groups (such as –Br, –Cl, –OCH₃, –CHO, and –NO₂) and double bond.     

No effect of creatine supplementation on oxidative stress and cardiovascular parameters in spontaneously hypertensive rats

Background

Exacerbated oxidative stress is thought to be a mediator of arterial hypertension. It has been postulated that creatine (Cr) could act as an antioxidant agent preventing increased oxidative stress. The aim of this study was to investigate the effects of nine weeks of Cr or placebo supplementation on oxidative stress and cardiovascular parameters in spontaneously hypertensive rats (SHR).

Findings

Lipid hydroperoxidation, one important oxidative stress marker, remained unchanged in the coronary artery (Cr: 12.6 ± 1.5 vs. Pl: 12.2 ± 1.7 nmol·mg^-1; p = 0.87), heart (Cr: 11.5 ± 1.8 vs. Pl: 14.6 ± 1.1 nmol·mg^-1; p = 0.15), plasma (Cr: 67.7 ± 9.1 vs. Pl: 56.0 ± 3.2 nmol·mg^-1; p = 0.19), plantaris (Cr: 10.0 ± 0.8 vs. Pl: 9.0 ± 0.8 nmol·mg^-1; p = 0.40), and EDL muscle (Cr: 14.9 ± 1.4 vs. Pl: 17.2 ± 1.5 nmol·mg^-1; p = 0.30). Additionally, Cr supplementation affected neither arterial blood pressure nor heart structure in SHR (p > 0.05).

Conclusions

Using a well-known experimental model of systemic arterial hypertension, this study did not confirm the possible therapeutic effects of Cr supplementation on oxidative stress and cardiovascular dysfunction associated with arterial hypertension.     

Rapid and selective separation for mixed proteins with thiol functionalized magnetic nanoparticles

ABSTRACT: Thiol group functionalized silica-coated magnetic nanoparticles (Si-MNPs@SH) were synthesized for rapid and selective magnetic field-based separation of mixed proteins. The highest adsorption efficiencies of binary proteins, bovine serum albumin (BSA; 66 kDa; pI = 4.65) and lysozyme (LYZ; 14.3 kDa; pI = 11) were shown at the pH values corresponding to their own pI in the single-component protein. In the mixed protein, however, the adsorption performance of BSA and LYZ by Si-MNPs@SH was governed not only by pH but also by the molecular weight of each protein in the mixed protein.     

Graphene transfer: key for applications

The first micrometer-sized graphene flakes extracted from graphite demonstrated outstanding electrical, mechanical and chemical properties, but they were too small for practical applications. However, the recent advances in graphene synthesis and transfer techniques have enabled various macroscopic applications such as transparent electrodes for touch screens and light-emitting diodes (LEDs) and thin-film transistors for flexible electronics in particular. With such exciting potential, a great deal of effort has been put towards producing larger size graphene in the hopes of industrializing graphene production. Little less than a decade after the first discovery, graphene now can be synthesized up to 30 inches in its diagonal size using chemical vapour deposition methods. In making this possible, it was not only the advances in the synthesis techniques but also the transfer methods that deliver graphene onto target substrates without significant mechanical damage. In this article, the recent advancements in transferring graphene to arbitrary substrates will be extensively reviewed. The methods are categorized into mechanical exfoliation, polymer-assisted transfer, continuous transfer by roll-to-roll process, and transfer-free techniques including direct synthesis on insulating substrates.     

Competitive adsorption of protocatechuic acid and caffeic acid on C18 particles

Comparisons of protocatechuic acid (PA) and caffeic acid (CA) adsorption isotherm on C₁₈ column and competitive adsorption of the two compounds were investigated. By linear and nonlinear regression analysis, the experimental parameters in the equilibrium isotherms were estimated. Adsorption equilibrium data of the two compounds were investigated using six different models including linear, Langmuir, Freundlich, Langmuir-Freundlich, competitive Langmuir and Quadratic. In the moderate range of concentrations, the competitive Langmuir isotherm proved to be the best model for these experimental data. The regression coefficients of the competitive Langmuir adsorption isotherms were 0.9860 for PA and 0.9898 for CA, respectively. The coefficients obtained for the six isotherm models confirmed the superiority of the competitive Langmuir isotherm for analyzing the competitive adsorption data of solutes.     

Optical properties of TiO2 nanorods modified by electron-donating stabilizers

A significant change in the UV-vis absorption of TiO₂ nanorods (NRs) was induced by changing electrondonating stabilizer from oleic acid (OA) to acrylic acid (AcA). When TiO₂ NRs with an average size of 2.5 nm in diameter and 30 nm in length were dispersed in an aqueous AcA solution, a red shift in the optical absorption (0.73 eV at the band edge and 0.55 eV at the onset) was observed. The red shift was attributed to an increase in the electron density inside the TiO₂ NRs. The applicability of the AcA-exchanged TiO₂ NRs for the photocatalyst as well as a UV sensor was evaluated. The AcA-exchanged TiO₂ NRs showed significant photocatalytic activity on the degradation of toluene in the visible light region. Moreover, thin film of the AcA-exchanged TiO₂ NRs on a quartz plate was tested as a UV sensor and it exhibited a good response to a wide range of the UV light.