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"Phillip, William A."
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The Future of Seawater Desalination: Energy, Technology, and the Environment
In recent years, numerous large-scale seawater desalination plants have been built in water-stressed countries to augment available water resources, and construction of new desalination plants is expected to increase in the near future. Despite major advancements in desalination technologies, seawater desalination is still more energy intensive compared to conventional technologies for the treatment of fresh water. There are also concerns about the potential environmental impacts of large-scale seawater desalination plants. Here, we review the possible reductions in energy demand by state-of-the-art seawater desalination technologies, the potential role of advanced materials and innovative technologies in improving performance, and the sustainability of desalination as a technological solution to global water shortages.
Journal Article
Achieving high permeability and enhanced selectivity for Angstrom-scale separations using artificial water channel membranes
Synthetic polymer membranes, critical to diverse energy-efficient separations, are subject to permeability-selectivity trade-offs that decrease their overall efficacy. These trade-offs are due to structural variations (e.g., broad pore size distributions) in both nonporous membranes used for Angstrom-scale separations and porous membranes used for nano to micron-scale separations. Biological membranes utilize well-defined Angstrom-scale pores to provide exceptional transport properties and can be used as inspiration to overcome this trade-off. Here, we present a comprehensive demonstration of such a bioinspired approach based on pillar[5]arene artificial water channels, resulting in artificial water channel-based block copolymer membranes. These membranes have a sharp selectivity profile with a molecular weight cutoff of ~ 500 Da, a size range challenging to achieve with current membranes, while achieving a large improvement in permeability (~65 L m
−2
h
−1
bar
−1
compared with 4–7 L m
−2
h
−1
bar
−1
) over similarly rated commercial membranes.
Synthetic polymeric membranes used for separations suffer from permeability-selectivity trade-offs. Here the authors demonstrate how a bioinspired pillar[5]arene artificial water channel embedded in a copolymer membrane can improve selectivity while still achieving high permeability.
Journal Article
Rapid fabrication of precise high-throughput filters from membrane protein nanosheets
Biological membranes are ideal for separations as they provide high permeability while maintaining high solute selectivity due to the presence of specialized membrane protein (MP) channels. However, successful integration of MPs into manufactured membranes has remained a significant challenge. Here, we demonstrate a two-hour organic solvent method to develop 2D crystals and nanosheets of highly packed pore-forming MPs in block copolymers (BCPs). We then integrate these hybrid materials into scalable MP-BCP biomimetic membranes. These MP-BCP nanosheet membranes maintain the molecular selectivity of the three types of β-barrel MP channels used, with pore sizes of 0.8 nm, 1.3 nm, and 1.5 nm. These biomimetic membranes demonstrate water permeability that is 20–1,000 times greater than that of commercial membranes and 1.5–45 times greater than that of the latest research membranes with comparable molecular exclusion ratings. This approach could provide high performance alternatives in the challenging sub-nanometre to few-nanometre size range.
Protein channels are highly selective, but application in membranes is limited due to low protein content. Here, protein channels are embedded into block copolymers to form nanosheets using rapid solvent casting, with better water permeability and similar molecular exclusions relative to other membrane systems.
Journal Article
Publisher Correction: Achieving high permeability and enhanced selectivity for Angstrom-scale separations using artificial water channel membranes
The original version of this Article contained an error in the spelling of the author Woochul Song, which was incorrectly given as Woochul C. Song. This has been corrected in both the PDF and HTML versions of the Article.
Journal Article
Fit-for-purpose block polymer membranes molecularly engineered for water treatment
Continued stresses on fresh water supplies necessitate the utilization of non-traditional resources to meet the growing global water demand. Desalination and hybrid membrane processes are capable of treating non-traditional water sources to the levels demanded by users. Specifically, desalination can produce potable water from seawater, and hybrid processes have the potential to recover valuable resources from wastewater while producing water of a sufficient quality for target applications. Despite the demonstrated successes of these processes, state-of-the-art membranes suffer from limitations that hinder the widespread adoption of these water treatment technologies. In this review, we discuss nanoporous membranes derived from self-assembled block polymer precursors for the purposes of water treatment. Due to their well-defined nanostructures, myriad chemical functionalities, and the ability to molecularly-engineer these properties rationally, block polymer membranes have the potential to advance water treatment technologies. We focus on block polymer-based efforts to: (1) nanomanufacture large areas of high-performance membranes; (2) reduce the characteristic pore size and push membranes into the reverse osmosis regime; and (3) design and implement multifunctional pore wall chemistries that enable solute-specific separations based on steric, electrostatic, and chemical affinity interactions. The use of molecular dynamics simulations to guide block polymer membrane design is also discussed because its ability to systematically examine the available design space is critical for rapidly translating fundamental understanding to water treatment applications. Thus, we offer a full review regarding the computational and experimental approaches taken in this arena to date while also providing insights into the future outlook of this emerging technology.
Journal Article
Thermal-energy conversion: Under pressure
The conversion of low-grade waste heat into electrical energy is an attractive opportunity to harvest a sustainable energy resource. A thermo-osmotic energy conversion process that uses Earth-abundant materials has now been shown to convert waste heat into electrical energy from sources at temperatures as low as 40 °C.
Journal Article
Block polymer membranes for selective separations
Polymeric membranes are used for many separations. Some act as selective filters, separating viruses and other undesirable solutes from drinking water. Others perform chemical separations, separating air to make an atmosphere which extends fruit shelf-life. The ability of a membrane to perform a separation is determined by its chemistry and microstructure. Block polymers are macromolecules composed of two or more chemically incompatible polymers (blocks) covalently bonded together. Depending upon the relative amounts of each block, the polymer forms different ordered structures 5-50 nm in scale. This control over the constituent polymers and microstructure will be used to produce membranes with different transport properties. Ammonia selective membranes which retain selectivity in mixed gas systems are made from poly(cycloocetene-b-styrene sulfonate). Using poly(styrene-b-lactide) as a template, ultrafiltration membranes with a monodisperse pore size distribution are formed.
Dissertation
The opportunity cost of androgen suppression in locally advanced prostate cancer
The use of androgen suppression ther- apy （AST） and radiotherapy for locallyadvanced prostate cancer has become the standard of care worldwide. At the same time, it has become clear that AST carries significant risk for side effects. Recently, Denham and colleagues have reported ini- tial quality of life （QoL） results from the TROG 03.04 RADAR trial. The authors identify clinically meaningful decrements in patient-reported QoL for those treated with 18 months of AST vs. 6 months but only marginal differences at 36 months. Once survival data becomes available, these data will help to frame any benefits seen for longer courses of AST.
Journal Article
Longitudinal assessment of sputum microbiome by sequencing of the 16S rRNA gene in non-cystic fibrosis bronchiectasis patients
Bronchiectasis is accompanied by chronic bronchial infection that may drive disease progression. However, the evidence base for antibiotic therapy is limited. DNA based methods offer better identification and quantification of microbial constituents of sputum than standard clinical culture and may help inform patient management strategies. Our study objective was to determine the longitudinal variability of the non-cystic fibrosis (CF) bronchiectasis microbiome in sputum with respect to clinical variables. Eighty-five patients with non-CF bronchiectasis and daily sputum production were recruited from outpatient clinics and followed for six months. Monthly sputum samples and clinical measurements were taken, together with additional samples during exacerbations. 16S rRNA gene sequencing of the sputum microbiota was successful for 381 samples from 76 patients and analysed in conjunction with clinical data.
Microbial communities were highly individual in composition and stability, usually with limited diversity and often containing multiple pathogens. When compared to DNA sequencing, microbial culture had restricted sensitivity in identifying common pathogens such as Pseudomonas aeruginosa, Haemophilus influenzae, Moraxella catarrhalis. With some exceptions, community characteristics showed poor correlations with clinical features including underlying disease, antibiotic use and exacerbations, with the subject showing the strongest association with community structure. When present, the pathogens mucoid Pseudomonas aeruginosa and Haemophilus influenzae may also shape the structure of the rest of the microbial community.
The use of microbial community analysis of sputum added to information from microbial culture. A simple model of exacerbations driven by bacterial overgrowth was not supported, suggesting a need for revision of principles for antibiotic therapy. In individual patients, the management of chronic bronchial infection may be improved by therapy specific to their microbiome, taking into account pathogen load, community stability, and acute and chronic community responses to antibiotics.
Journal Article