Chlorinated volatile organic compounds (CVOCs) and 1,4-dioxane kinetics and equilibrium adsorption studies on selective macrocyclic adsorbents.

Chlorinated volatile organic compounds (CVOCs) are often found in combination with 1,4-dioxane which has been used as a solvent stabilizer. It would be desirable to separate these compounds since biodegradation of 1,4-dioxane follows an aerobic pathway while anaerobic conditions are needed for biodegrading CVOCs. Conventional adsorbents such as activated carbon (AC) and carbonaceous resins have high adsorption capacities for 1,4-dioxane and CVOCs but lack selectivity, limiting their use for separation (Liu et al.

Isolation and characterization of pure cultures for metabolizing 1,4-dioxane in oligotrophic environments.

1,4-Dioxane concentration in most contaminated water is much less than 1 mg/L, which cannot sustain the growth of most reported 1,4-dioxane-metabolizing pure cultures. These pure cultures were isolated following enrichment of mixed cultures at high concentrations (20 to 1,000 mg/L). This study is based on a different strategy: 1,4-dioxane-metabolizing mixed cultures were enriched by periodically spiking 1,4-dioxane at low concentrations (≤1 mg/L).

Application of β-Cyclodextrin Adsorbents in the Removal of Mixed Per- and Polyfluoroalkyl Substances.

The extensive use of per- and polyfluoroalkyl substances (PFASs) in industrial consumer products has led to groundwater contamination, raising concerns for human health and the environment. These persistent chemicals exist in different forms with varying properties, which makes their removal challenging. In this study, we assessed the effectiveness of three different β-cyclodextrin (β-CD) adsorbents at removing a mixture of PFASs, including anionic, neutral, and zwitterionic compounds, at neutral pH.

Photosynthetic biohybrid coculture for tandem and tunable CO and N fixation.

Solar-driven bioelectrosynthesis represents a promising approach for converting abundant resources into value-added chemicals with renewable energy. Microorganisms powered by electrochemical reducing equivalents assimilate CO, HO, and N building blocks. However, products from autotrophic whole-cell biocatalysts are limited.

Enhancing Biohybrid CO to Multicarbon Reduction via Adapted Whole-Cell Catalysts.

Catalytic CO conversion to renewable fuel is of utmost importance to establish a carbon-neutral society. Bioelectrochemical CO reduction, in which a solid cathode interfaces with CO-reducing bacteria, represents a promising approach for renewable and sustainable fuel production. The rational design of biocatalysts in the biohybrid system is imperative to effectively reduce CO into valuable chemicals.

Beating natural proteins at filtering water.

Artificial fluorous channels outperform aquaporins in water permeation.

Interaction between humic acid and silica in reverse osmosis membrane fouling process: A spectroscopic and molecular dynamics insight.

Combined organic and inorganic fouling is a primary barrier constraining the performance of reverse osmosis (RO) membrane. In this work, we conducted a systematic study focusing on the synergetic fouling effects of silica and humic acid (HA) in RO process, and found the critical silica concentration where the fouling pattern changed qualitatively. When the silica concentration was lower than 6 mM at a typical HA concentration of 50 mg·L, no severe fouling was observed, while silica reaching this critical point could cause severe synergetic fouling with HA.

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).

Author Correction: Artificial water channels enable fast and selective water permeation through water-wire networks.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Artificial water channels enable fast and selective water permeation through water-wire networks.

Artificial water channels are synthetic molecules that aim to mimic the structural and functional features of biological water channels (aquaporins). Here we report on a cluster-forming organic nanoarchitecture, peptide-appended hybrid[4]arene (PAH[4]), as a new class of artificial water channels. Fluorescence experiments and simulations demonstrated that PAH[4]s can form, through lateral diffusion, clusters in lipid membranes that provide synergistic membrane-spanning paths for a rapid and selective water permeation through water-wire networks.

Stokes Shift and Specific Fluorescence as Potential Indicators of Organic Matter Hydrophobicity and Molecular Weight in Membrane Bioreactors.

Hydrophobicity and molecular weight (MW) are two fundamental properties of dissolved organic matter (DOM) in wastewater treatment systems. This study proposes fluorescence Stokes shift and specific fluorescence intensity (SFI) as novel indicators of hydrophobicity and MW. These indicators originate from the energy gap and photon efficiency of the fluorescence process and can be readily extracted from a fluorescence excitation-emission matrix (EEM).

Characteristic Regions of the Fluorescence Excitation-Emission Matrix (EEM) To Identify Hydrophobic/Hydrophilic Contents of Organic Matter in Membrane Bioreactors.

This study systematically investigated the correlations between fluorescence distributions characterized by the excitation-emission matrix (EEM) and hydrophobic/hydrophilic composition of dissolved organic matter (DOM) in membrane bioreactors (MBRs). On the basis of samples from 10 full-scale MBRs, we performed point-to-point comparisons among different components using an EEM fluorescence quotient (FQ) method and obtained a hydrophobic/hydrophilic fluorophore distribution map via Wilcoxon signed rank test. Hydrophobic acids/bases (HOA/HOB) concentrated in the low-wavelength region [excitation wavelength (Ex) < 235 nm], while hydrophilic substances (HIS) were enriched in the region of Ex > 235 nm [especially with emission wavelength (Em) = 300-360 nm].

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.

Electron tomography reveals details of the internal microstructure of desalination membranes.

As water availability becomes a growing challenge in various regions throughout the world, desalination and wastewater reclamation through technologies such as reverse osmosis (RO) are becoming more important. Nevertheless, many open questions remain regarding the internal structure of thin-film composite RO membranes. In this work, fully aromatic polyamide films that serve as the active layer of state-of-the-art water filtration membranes were investigated using high-angle annular dark-field scanning transmission electron microscopy tomography.

Unique selectivity trends of highly permeable PAP[5] water channel membranes.

Artificial water channels are a practical alternative to biological water channels for achieving exceptional water permeability and selectivity in a stable and scalable architecture. However, channel-based membrane fabrication faces critical barriers such as: (1) increasing pore density to achieve measurable gains in permeability while maintaining selectivity, and (2) scale-up to practical membrane sizes for applications. Recently, we proposed a technique to prepare channel-based membranes using peptide-appended pillar[5]arene (PAP[5]) artificial water channels, addressing the above challenges.

Creating cross-linked lamellar block copolymer supporting layers for biomimetic membranes.

The long-standing goal in membrane development is creating materials with superior transport properties, including both high flux and high selectivity. These properties are common in biological membranes, and thus mimicking nature is a promising strategy towards improved membrane design. In previous studies, we have shown that artificial water channels can have excellent water transport abilities that are comparable to biological water channel proteins, aquaporins.

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.

Membrane Protein Insertion into and Compatibility with Biomimetic Membranes.

Membrane protein and membrane protein-mimic functionalized materials are rapidly gaining interest across a wide range of applications, including drug screening, DNA sequencing, drug delivery, sensors, water desalination, and bioelectronics. In these applications, material performance is highly dependent on activity-per-protein and protein packing density in bilayer and bilayer-like structures collectively known as biomimetic membranes. However, a clear understanding of, and accurate tools to study these properties of biomimetic membranes does not exist.

Multiple antibiotic resistance genes distribution in ten large-scale membrane bioreactors for municipal wastewater treatment.

Wastewater treatment plants are thought to be potential reservoirs of antibiotic resistance genes. In this study, GeoChip was used for analyzing multiple antibiotic resistance genes, including four multidrug efflux system gene groups and three β-lactamase genes in ten large-scale membrane bioreactors (MBRs) for municipal wastewater treatment. Results revealed that the diversity of antibiotic genes varied a lot among MBRs, but about 40% common antibiotic resistance genes were existent.

Salt-Excluding Artificial Water Channels Exhibiting Enhanced Dipolar Water and Proton Translocation.

Aquaporins (AQPs) are biological water channels known for fast water transport (∼10(8)-10(9) molecules/s/channel) with ion exclusion. Few synthetic channels have been designed to mimic this high water permeability, and none reject ions at a significant level. Selective water translocation has previously been shown to depend on water-wires spanning the AQP pore that reverse their orientation, combined with correlated channel motions.

Highly permeable artificial water channels that can self-assemble into two-dimensional arrays.

Bioinspired artificial water channels aim to combine the high permeability and selectivity of biological aquaporin (AQP) water channels with chemical stability. Here, we carefully characterized a class of artificial water channels, peptide-appended pillar[5]arenes (PAPs). The average single-channel osmotic water permeability for PAPs is 1.

Linkages between microbial functional potential and wastewater constituents in large-scale membrane bioreactors for municipal wastewater treatment.

Large-scale membrane bioreactors (MBRs) have been widely used for the municipal wastewater treatment, whose performance relies on microbial communities of activated sludge. Nevertheless, microbial functional structures in MBRs remain little understood. To gain insight into functional genes and their steering environmental factors, we adopted GeoChip, a high-throughput microarray-based tool, to examine microbial genes in four large-scale, in-operation MBRs located in Beijing, China.

Molecular cloning, overexpression and characterization of a novel water channel protein from Rhodobacter sphaeroides.

Aquaporins are highly selective water channel proteins integrated into plasma membranes of single cell organisms; plant roots and stromae; eye lenses, renal and red blood cells in vertebrates. To date, only a few microbial aquaporins have been characterized and their physiological importance is not well understood. Here we report on the cloning, expression and characterization of a novel aquaporin, RsAqpZ, from a purple photosynthetic bacterium, Rhodobacter sphaeroides ATCC 17023.

Improvement on the modified Lowry method against interference of divalent cations in soluble protein measurement.

This paper systematically investigated the interference of calcium and magnesium in protein measurement with a modified Lowry method first proposed by Frølund et al. (Appl Microbiol Biotechnol 43:755-761, 1995). This interference has in the past been largely ignored resulting in variable and unreliable results when applied to natural water matrices.

High-density reconstitution of functional water channels into vesicular and planar block copolymer membranes.

The exquisite selectivity and unique transport properties of membrane proteins can be harnessed for a variety of engineering and biomedical applications if suitable membranes can be produced. Amphiphilic block copolymers (BCPs), developed as stable lipid analogs, form membranes that functionally incorporate membrane proteins and are ideal for such applications. While high protein density and planar membrane morphology are most desirable, BCP-membrane protein aggregates have so far been limited to low protein densities in either vesicular or bilayer morphologies.