Membrane separation properties are constrained by a tradeoff relationship between permeability and selectivity. This tradeoff relationship has been well established for gas separation membranes in ...the form of the Robeson's upper bound. In contrast, the upper bound relationship is much less established for thin-film composite (TFC) polyamide membranes used for desalination. In this work, we analyzed the tradeoff between the water permeance and the water/NaCl selectivity for TFC membranes gathered from more than 300 published papers. A clear upper bound behavior relationship is established, and the various effects of membrane synthesis conditions and modifications are reviewed in relation to this permeance-selectivity tradeoff. Our work provides a critical tool for the evaluation and benchmarking of future membrane development works in the context of desalination and water reuse.
Display omitted
•TFC polyamide membranes are constrained by permeance-selectivity tradeoff.•An upper bound is established based on TFC membranes from >300 papers.•The upper bound is given by A/B = 16000A−3.2 (A/B in bar−1 and A in Lm−2h−1bar−1).•The effects of various parameters on membrane performance are summarized.
In situ, reversible coacervate formation within lipid vesicles represents a key step in the development of responsive synthetic cellular models. Herein, we exploit the pH responsiveness of a ...polycation above and below its pKa, to drive liquid–liquid phase separation, to form single coacervate droplets within lipid vesicles. The process is completely reversible as coacervate droplets can be disassembled by increasing the pH above the pKa. We further show that pH‐triggered coacervation in the presence of low concentrations of enzymes activates dormant enzyme reactions by increasing the local concentration within the coacervate droplets and changing the local environment around the enzyme. In conclusion, this work establishes a tunable, pH responsive, enzymatically active multi‐compartment synthetic cell. The system is readily transferred into microfluidics, making it a robust model for addressing general questions in biology, such as the role of phase separation and its effect on enzymatic reactions using a bottom‐up synthetic biology approach.
The pH responsiveness of a polycation above and below its pKa is used to drive liquid–liquid phase separation to form coacervate droplets within lipid vesicles. This is reversible as the coacervate droplets can be disassembled by increasing the pH above the pKa. pH‐triggered coacervation in the presence of low concentrations of enzymes activates dormant reactions as the local enzyme and substrate concentrations are increased in the coacervate droplets which concomitantly changes the local environment of enzymes and reactants.
A large German research consortium mainly within the Max Planck Society (“MaxSynBio”) was formed to investigate living systems from a fundamental perspective. The research program of MaxSynBio relies ...solely on the bottom‐up approach to synthetic biology. MaxSynBio focuses on the detailed analysis and understanding of essential processes of life through modular reconstitution in minimal synthetic systems. The ultimate goal is to construct a basic living unit entirely from non‐living components. The fundamental insights gained from the activities in MaxSynBio could eventually be utilized for establishing a new generation of biotechnological processes, which would be based on synthetic cell constructs that replace the natural cells currently used in conventional biotechnology.
To the Max: A research consortium associated with the Max Planck Society (“MaxSynBio”) was formed to investigate living systems from a fundamental perspective. The research program relies solely on the bottom‐up approach and focuses on the detailed analysis and understanding of essential processes of life through modular reconstitution in minimal synthetic systems. The ultimate goal is to construct a basic living unit entirely from non‐living components.
Massively parallel sequencing of DNA molecules in the plasma of pregnant women has been shown to allow accurate and noninvasive prenatal detection of fetal trisomy 21. However, whether the sequencing ...approach is as accurate for the noninvasive prenatal diagnosis of trisomy 13 and 18 is unclear due to the lack of data from a large sample set. We studied 392 pregnancies, among which 25 involved a trisomy 13 fetus and 37 involved a trisomy 18 fetus, by massively parallel sequencing. By using our previously reported standard z-score approach, we demonstrated that this approach could identify 36.0% and 73.0% of trisomy 13 and 18 at specificities of 92.4% and 97.2%, respectively. We aimed to improve the detection of trisomy 13 and 18 by using a non-repeat-masked reference human genome instead of a repeat-masked one to increase the number of aligned sequence reads for each sample. We then applied a bioinformatics approach to correct GC content bias in the sequencing data. With these measures, we detected all (25 out of 25) trisomy 13 fetuses at a specificity of 98.9% (261 out of 264 non-trisomy 13 cases), and 91.9% (34 out of 37) of the trisomy 18 fetuses at 98.0% specificity (247 out of 252 non-trisomy 18 cases). These data indicate that with appropriate bioinformatics analysis, noninvasive prenatal diagnosis of trisomy 13 and trisomy 18 by maternal plasma DNA sequencing is achievable.
The utilization of osmosis for engineered applications sparked off various emerging technologies relying on osmotically driven membrane processes (ODMPs). Represented by forward osmosis (FO) and ...pressure retarded osmosis (PRO), ODMPs show great promise to leverage the global water-energy nexus and have drawn considerable attention in recent years. However, their performance in practical applications is significantly affected by membrane fouling. Membrane fouling is a complex problem and is associated with the foulant deposition, concentration polarization and reverse solute diffusion (RSD) in ODMPs. The current paper provides a comprehensive review on membrane fouling in ODMPs with a focus on the elaboration of the factors and mechanisms governing the fouling behavior. Among those fouling factors and mechanisms, some are also applicable for pressure-driven membrane processes (e.g., reverse osmosis (RO) and nanofiltration (NF)), such as the effects of hydrodynamic conditions, feedwater composition, and membrane material and properties, and the cake-enhanced concentration polarization (CE-CP) mechanism. Others are unique for ODMPs, such as the effects of draw solution composition and membrane orientation, the internal concentration polarization (ICP) self-compensation effect, and the RSD-enhanced fouling. A general osmotic-resistance filtration model for ODMPs is presented in this paper to assist in the interpretation of the intrinsic interrelationships among those fouling factors and mechanisms. The impact and mechanisms of membrane fouling on contaminates removal are also reviewed briefly based on the limited existing literature on this topic. Finally, the available membrane fouling control strategies for ODMPs are summarized upon understanding the cause and effect of fouling. Based on the current review, future research prospects are proposed for further studying the membrane fouling in ODMPs.
Display omitted
•Membrane fouling in osmotically-driven membrane processes (ODMPs) is comprehensively reviewed.•An osmotic-resistance filtration model is proposed for interpreting the effects of fouling in ODMPs.•Effect and mechanisms of membrane fouling on contaminants removal are reviewed.•Strategies for mitigating membrane fouling are discussed.•Future research needs on membrane fouling and control in ODMPs are recommended.
A solution is given to a conjecture proposed recently by Y. Wigderson and A. Wigderson concerning a “Heisenberg-like” uncertainty principle. That conjecture is about the image of the map
f
↦
f
q
f
⌢
...q
f
2
f
⌢
2
,
f
∈
ℓ
ℝ
\
0
,
where ℓ(ℝ) stands for the Schwartz class of functions on the real line. Also, a more general question is answered, where the
L
2
norm is replaced by the
L
p
norm in the denominator.
It has long been proposed that phase-separated compartments can provide a basis for the formation of cellular precursors in prebiotic environments. However, we know very little about the properties ...of coacervates formed from simple peptides, their compatibility with ribozymes or their functional significance. Here we assess the conditions under which functional ribozymes form coacervates with simple peptides. We find coacervation to be most robust when transitioning from long homopeptides to shorter, more pre-biologically plausible heteropeptides. We mechanistically show that these RNA-peptide coacervates display peptide-dependent material properties and cofactor concentrations. We find that the interspacing of cationic and neutral amino acids increases RNA mobility, and we use isothermal calorimetry to reveal sequence-dependent Mg
partitioning, two critical factors that together enable ribozyme activity. Our results establish how peptides of limited length, homogeneity and charge density facilitate the compartmentalization of active ribozymes into non-gelating, magnesium-rich coacervates, a scenario that could be applicable to cellular precursors with peptide-dependent functional phenotypes.
Lithium production has become increasingly critical for sustainable development. The extraction of lithium from aqueous sources, particularly salt-lake brine, has become a trend in the lithium ...recovery industry because of its low cost and abundant reserves. Among various technologies applied for lithium recovery, membrane processes driven by pressure, electrical field, and thermal gradient have received considerable attention in the past few decades because of their high energy efficiency and low environmental impact. This paper presents a comprehensive review of the advantages and challenges of the current membrane-based technologies applied to the recovery of a water lithium resource. Here, we highlight that the combination of membrane processes (e.g. nanofiltration, selective electrodialysis, and membrane distillation crystallization) with a conventional lithium precipitation process will lead to higher performance efficiency and lower cost. Although the membrane-based separation technology is technically feasible, it is restricted by its high capital and operating costs. Therefore, the future development of membrane-based technologies should include efforts for the improvement of the separation efficiency, material stability, and some engineering aspects such as membrane fouling control, module design, and process optimisation.
Display omitted
•Membrane-based technologies for lithium recovery from water resource are reviewed.•Technologies covered in review include NF, SLM, IIM, LISM, MDC, S-ED and PSMCDI.•The advantages and challenges of these membrane-based technologies are explained.•The techno-economic feasibility of these technologies is evaluated.•The diresssssctions for future research and development are identified.
PDF
