Physical filtration efficiency analysis of a polyaniline hybrid composite filter with graphite oxide for particulate matter 2.5

Particulate matter (PM) 2.5 pollution is a prevalent environmental and public health issue that has raised serious global concerns. Because standard heating, ventilation, and air conditioning filters are incapable of filtering out PM 2.5 particles efficiently, different methods of PM 2.5 filtration, such as physical filtration and electrostatic filtration, are under investigation to develop a filter with a high filtration efficiency and a low pressure drop. According to various studies, pressure drop has a significant influence on the filtration efficiency. An equation for the theoretical trend was generated based on the composite data gathered from similar filtration studies and was used to evaluate the relationship between pressure drop and filtration efficiency. Here, the theoretical equation indicated that the filtration efficiency increased as the pressure drop on a filter increased until 0.01 psi where the efficiency remained near constant at approximately 99.9%. In this study, we introduce a graphite oxide (GO) and polyaniline (PANi) composite hybrid filter in order to create a low-pressure (1.2 psi) drop filter. By adding GO flakes to the PANi matrix, we not only produced a highly permeable filter while allowing continuous gas flow, but also achieved a remarkable and highly effective PM 2.5 filter with a filtration efficiency of 99.7 ± 0.08%.     

The Role of Cholesterol on Triterpenoid Saponin-Induced Endolysosomal Escape of a Saporin-Based Immunotoxin

Cholesterol seems to play a central role in the augmentation of saporin-based immunotoxin (IT) cytotoxicity by triterpenoid saponins. Endolysosomal escape has been proposed as one mechanism for the saponin-mediated enhancement of targeted toxins. We investigated the effects of lipid depletion followed by repletion on Saponinum album (SA)-induced endolysosomal escape of Alexa Fluor labelled saporin and the saporin-based immunotoxin OKT10-SAP, directed against CD38, in Daudi lymphoma cells. Lipid deprived cells showed reduced SA-induced endolysosomal escape at two concentrations of SA, as determined by a flow cytometric method. The repletion of membrane cholesterol by low density lipoprotein (LDL) restored SA-induced endolysosomal escape at a concentration of 5 µg/mL SA but not at 1 µg/mL SA. When LDL was used to restore the cholesterol levels in lipid deprived cells, the SA augmentation of OKT10-SAP cytotoxicity was partially restored at 1 µg/mL SA and fully restored at 5 µg/mL SA. These results suggest that different mechanisms of action might be involved for the two different concentrations of SA and that endosomal escape may not be the main mechanism for the augmentation of saporin IT cytotoxicity by SA at the sub-lytic concentration of 1 µg/mL SA.     

Tunable temperature‐ and shear‐responsive hydrogels based on poly(alkyl glycidyl ether)s

We describe the synthesis, characterization and direct‐write 3D printing of triblock copolymer hydrogels that have a tunable response to temperature and shear stress. In aqueous solutions, these polymers utilize the temperature‐dependent self‐association of poly(alkyl glycidyl ether) ‘A’ blocks and a central poly(ethylene oxide) segment to create a physically crosslinked three‐dimensional network. The temperature response of these hydrogels was dependent upon composition, chain length and concentration of the ‘A’ block in the copolymer. Rheological experiments confirmed the existence of sol–gel transitions and the shear‐thinning behavior of the hydrogels. The temperature‐ and shear‐responsive properties enabled direct‐write 3D printing of complex objects with high fidelity. Hydrogel cytocompatibility was also confirmed by incorporating HeLa cells into select hydrogels resulting in high viabilities over 24 h. The tunable temperature response and innate shear‐thinning properties of these hydrogels, coupled with encouraging cell viability results, present an attractive opportunity for additive manufacturing and tissue engineering applications. © 2018 Society of Chemical Industry     

Plasmonic‐Induced Photon Recycling in Metal Halide Perovskite Solar Cells

Organic–inorganic metal halide perovskite solar cells have emerged in the past few years to promise highly efficient photovoltaic devices at low costs. Here, temperature‐sensitive core–shell Ag@TiO₂ nanoparticles are successfully incorporated into perovskite solar cells through a low‐temperature processing route, boosting the measured device efficiencies up to 16.3%. Experimental evidence is shown and a theoretical model is developed which predicts that the presence of highly polarizable nanoparticles enhances the radiative decay of excitons and increases the reabsorption of emitted radiation, representing a novel photon recycling scheme. The work elucidates the complicated subtle interactions between light and matter in plasmonic photovoltaic composites. Photonic and plasmonic schemes such as this may help to move highly efficient perovskite solar cells closer to the theoretical limiting efficiencies.     

Water and Wastewater Minimization: the Aire and Calder Project

The reduction of the waste of raw materials at source using clean technologies, recycling, and good housekeeping has considerable benefits for both the environment and industry. A demonstration project on wastewater minimization was completed in 1995 in the Aire and Calder catchments of West Yorkshire. The findings indicated cost savings for eleven firms of over $3 million/annum and further opportunities which, when implemented, could realize another $1 million/annum. The reduction in the amount of wastewater discharged either to sewer or river was 27%, with a potential to increase to over 40%. The payback period for 63% of the waste minimization opportunities is less than one year and many involve only a small initial investment. Waste minimization when widely adopted has prospects for cutting industry's costs, reducing demand for water and reducing the volume of effluent produced.     

The influence of oxidation reduction potential and water treatment processes on quartz lamp sleeve fouling in ultraviolet disinfection reactors

Ultraviolet (UV) disinfection systems are incorporated into drinking water production facilities because of their broad-spectrum antimicrobial capabilities, and the minimal disinfection by-product formation that generally accompanies their use. Selection of an optimal location for a UV system within a drinking water treatment facility depends on many factors; a potentially important consideration is the effect of system location on operation and maintenance issues, including the potential for fouling of quartz surfaces. To examine the effect of system location on fouling, experiments were conducted at a groundwater treatment facility, wherein aeration, chlorination, and sand filtration were applied sequentially for treatment. In this facility, access to the water stream was available prior to and following each of the treatment steps. Therefore, it was possible to examine the effects of each of these unit operations on fouling dynamics within a UV system. Results indicated zero-order formation kinetics for the fouling reactions at all locations. Increases in oxidation reduction potential, caused by water treatment steps such as aeration and chlorination, increased the rate of sleeve fouling and the rate of irradiance loss within the reactor. Analysis of metals in the sleeve foulant showed that calcium and iron predominate, and relative comparisons of foulant composition to water chemistry highlighted a high affinity for incorporation into the foulant matrix for both iron and manganese, particularly after oxidizing treatment steps. Fouling behavior was observed to be in qualitative agreement with representations of the degree of saturation, relative to the metal:ligand combinations that are believed to comprise a large fraction of the foulants that accumulate on the surfaces of quartz jackets in UV systems used to treat water.     

Accelerated development of CuSbS2 thin film photovoltaic device prototypes

Development of alternative thin film photovoltaic technologies is an important research topic because of the potential of low‐cost, high‐efficiency solar cells to produce terawatt levels of clean power. However, this development of unexplored yet promising absorbers can be hindered by complications that arise during solar cell fabrication. Here, a high‐throughput combinatorial method is applied to accelerate development of photovoltaic devices, in this case, using the novel CuSbS₂ absorber via a newly developed three‐stage self‐regulated growth process to control absorber purity and orientation. Photovoltaic performance of the absorber, using the typical substrate CuIn_xGa_{1 − x}Se₂ (CIGS) device architecture, is explored as a function of absorber quality and thickness using a variety of back contacts. This study yields CuSbS₂ device prototypes with ~1% conversion efficiency, suggesting that the optimal CuSbS₂ device fabrication parameters and contact selection criteria are quite different than for CIGS, despite the similarity of these two absorbers. The CuSbS₂ device efficiency is at present limited by low short‐circuit current because of bulk recombination related to defects, and a small open‐circuit voltage because of a theoretically predicted cliff‐type conduction band offset between CuSbS₂ and CdS. Overall, these results illustrate both the potential and limits of combinatorial methods to accelerate the development of thin film photovoltaic devices using novel absorbers. Copyright © 2016 John Wiley & Sons, Ltd.