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Fabrication of covalent organic framework (COF) membranes for molecular transport has excited highly pragmatic interest as a low energy and cost-effective route for molecular separations. However, currently, most COF membranes are assembled via a one-step procedure in liquid phase(s) by concurrent polymerization and crystallization, which are often accompanied by a loosely packed and less ordered structure. Herein, we propose a two-step procedure via a phase switching strategy, which decouples the polymerization process and the crystallization process to assemble compact and highly crystalline COF membranes. In the pre-assembly step, the mixed monomer solution is casted into a pristine membrane in the liquid phase, along with the completion of polymerization process. In the assembly step, the pristine membrane is transformed into a COF membrane in the vapour phase of solvent and catalyst, along with the completion of crystallization process. Owing to the compact and highly crystalline structure, the resultant COF membranes exhibit an unprecedented permeance (water ≈ 403 L m −2  bar −1  h −1 and acetonitrile ≈ 519 L m −2  bar −1  h −1 ). Our two-step procedure via phase switching strategy can open up a new avenue to the fabrication of advanced organic crystalline microporous membranes. Covalent organic framework (COF) membranes are important in low energy and cost-effective molecular separations but most COF membranes are assembled via a one-step procedure by concurrent polymerization and crystallization which compromises the ordered structure. Here, the authors propose a two-step phase switching strategy for assembling compact and highly crystalline COF membranes decoupling the polymerization and the crystallization process.

Ionic covalent organic frameworks (iCOFs) are new examples of porous materials and have shown great potential for various applications. When functionalized with suitable emission sites, guest uptake via the ionic moieties of iCOFs can cause a significant change in luminescence, making them excellent candidates for chemosensors. In here, we present a luminescence sensor in the form of an ionic covalent organic framework (TGH + •PD) composed of guanidinium and phenanthroline moieties for the detection of ammonia and primary aliphatic amines. TGH + •PD exhibits strong emission enhancement in the presence of selective primary amines due to the suppression of intramolecular charge transfer (ICT) with an ultra-low detection limit of 1.2 × 10 ‒7 M for ammonia. The presence of ionic moieties makes TGH + •PD highly dispersible in water, while deprotonation of the guanidinium moiety by amines restricts its ICT process and signals their presence by enhanced fluorescence emission. The presence of ordered pore walls introduces size selectivity among analyte molecules, and the iCOF has been successfully used to monitor meat products that release biogenic amine vapors upon decomposition due to improper storage. Ionic covalent organic frameworks (iCOFs) are new examples of porous materials and show great potential for various applications. Here, the authors demonstrate functionalization of an iCOFs with suitable emission sites and application as chemosensor for amine detection with high sensitivity which can be used to monitor meat spoilage.

In the stems of terrestrial vascular plants studied to date, the diameter of xylem water-conducting conduits D widens predictably with distance from the stem tip L approximating D ∝ Lb , with b ≈ 0.2. Because conduit diameter is central for conductance, it is essential to understand the cause of this remarkably pervasive pattern. We give reason to suspect that tip-to-base conduit widening is an adaptation, favored by natural selection because widening helps minimize the increase in hydraulic resistance that would otherwise occur as an individual stem grows longer and conductive path length increases. Evidence consistent with adaptation includes optimality models that predict the 0.2 exponent. The fact that this prediction can be made with a simple model of a single capillary, omitting much biological detail, itself makes numerous important predictions, e.g. that pit resistance must scale isometrically with conduit resistance. The idea that tip-to-base conduit widening has a nonadaptive cause, with temperature, drought, or turgor limiting the conduit diameters that plants are able to produce, is less consistent with the data than an adaptive explanation. We identify empirical priorities for testing the cause of tip-to-base conduit widening and underscore the need to study plant hydraulic systems leaf to root as integrated wholes.

Controlling the number of molecular switches and their relative positioning within porous materials is critical to their functionality and properties. The proximity of many molecular switches to one another can hinder or completely suppress their response. Herein, a synthetic strategy involving mixed linkers is used to control the distribution of spiropyran-functionalized linkers in a covalent organic framework (COF). The COF contains a spiropyran in each pore which exhibits excellent reversible photoswitching behavior to its merocyanine form in the solid state in response to UV/Vis light. The spiro-COF possesses an urchin-shaped morphology and exhibits a morphological transition to 2D nanosheets and vesicles in solution upon UV light irradiation. The merocyanine-equipped COFs are extremely stable and possess a more ordered structure with enhanced photoluminescence. This approach to modulating structural isomerization in the solid state is used to develop inkless printing media, while the photomediated polarity change is used for water harvesting applications. Controlling the number of molecular switches and their relative positioning within porous materials is critical to their functionality and properties. Here the authors systematically control the number of spiropyran units in a covalent organic framework using a mixed-linker synthetic strategy which resulted in one photoresponsive unit per pore.

It is common for studies that employ the comparative method for the study of adaptation, that is, documentation of potentially adaptive across-species patterns of trait–environment or trait–trait correlation, to be designated as “macroevolutionary.” Authors are justified in using “macroevolution” in this way by appeal to definitions such as “evolution above the species level.” I argue that regarding the comparative method as “macroevolutionary” is harmful because it hides in serious ways the true causal content of hypotheses tested with the comparative method. The comparative method is a means of testing hypotheses of adaptation and their alternatives. Adaptation is a population-level phenomenon, involving heritable interindividual variation that is associated with fitness differences. For example, given heritable intrapopulational variation, more streamlined individuals in populations of fast-moving aquatic animals have higher locomotory efficiency and thus better survivorship and more resources directed to reproduction than less streamlined ones. Direct evidence consistent with this population-level scenario includes the observation that many unrelated species of fast-moving aquatic animals have similar streamlined shapes, an example of the comparative method. Crucial to note in this example is that although the data are observed across species, the comparative method for studying adaptation tests hypotheses regarding standard population-level natural selection with no content that can be construed as “macro.” Even less “macro,” individual-level developmental dynamics can limit or bias the range of variants available for selection. Calling any of these studies “macroevolutionary” implies that some additional process is at work, shrouding the need to test adaptation hypotheses and study the range of variants that can be produced in development.

The moringa tree Moringa oleifera is a fast-growing, drought-resistant tree cultivated across the lowland dry tropics worldwide for its nutritious leaves. Despite its nutritious reputation, there has been no systematic survey of the variation in leaf nutritional quality across M. oleifera grown worldwide, or of the other species of the genus. To guide informed use of moringa, we surveyed protein, macro-, and micro- nutrients across 67 common garden samples of 12 Moringa taxa, including 23 samples of M. oleifera. Moringa oleifera, M. concanensis, M. stenopetala, an M. concanensis X oleifera hybrid, and M. longituba were highest in protein, with M. ruspoliana having the highest calcium levels. A protein-dry leaf mass tradeoff may preclude certain breeding possibilities, e.g. maximally high protein with large leaflets. These findings identify clear priorities and limitations for improved moringa varieties with traits such as high protein, calcium, or ease of preparation.

The goal of evolutionary biology is to explain the diversity of the entire sweep of the natural world; population biology only examines tiny slices of time of a few individuals of single species. What gives the tiny scale of population biology its relevance to evolutionary biology is the following assumption: processes identical or similar to those observed in a given population biology study are operative in unexamined individuals in the same species, have been operative throughout the history of the species, and are operative in other species. Without this assumption, population biology studies are just very detailed descriptions of a handful of individuals of a species. Population biology lacks the means to test its jusifying assumption. It is tested by the comparative method, studies of convergent evolution across species. The comparative method has its own blind spots, mainly its inability to examine intraspecific variation, heritability, and fitness directly, exactly the purview of population biology. Population and comparative biology thus provide complementary sources of direct evidence regarding evolutionary process. Both, along with optimality models, evo-devo studies of the variants that can or can’t be produced in development, together with assumptions about unseeable ancestral populations, make up essential parts of a maximally well-supported evolutionary explanation. Recognizing this essential epistemic interdependence shows why it is necessary to select sources of evidence from across population, comparative, optimality, and developmental studies, leading to collaboration rather than criticism across these fields, and stronger explanations accounting for the evolution of diversity in organismal form and function.

Plant ecology is increasingly turning to evolutionary questions, just as evolutionary biology pushes out of the strictures of the Modern Synthesis into what some regard as an “Extended Evolutionary Synthesis.” As plant ecology becomes increasingly evolutionary, it is essential to ask how aspects of the Extended Synthesis might impinge on plant ecological theory and practice. I examine the contribution of plant evolutionary ecology to niche construction theory, as well as the potential for developmental systems theory and genes-as-followers adaptive evolution, all important post-Modern Synthesis themes, in providing novel perspectives for plant evolutionary ecology. I also examine ways that overcoming dichotomies such as “genetic vs. plastic” and “constraint vs. adaptation” provide fertile opportunities for plant evolutionary ecologists. Along the same lines, outgrowing vague concepts such as “stress” and replacing them with more precise terminology in all cases provides vastly increased causal clarity. As a result, the synthetic path that plant ecologists are blazing, becoming more evolutionary every year, bodes extremely well for the field, with vast potential for expansion into important scientific territory.

Global climate change-induced droughts are provoking events of forest mortality worldwide, with loss of tree biomass and consequent ecosystem services. Ameliorating the effects of drought requires understanding the causes of forest mortality, with failure of the hydraulic system being an important contributor. Comparative anatomical data strongly suggest that, all else being equal, wider conduits are more vulnerable to drought-induced embolism than narrow ones. However, physiology experiments do not provide consistent support for such a link. If a vulnerability-diameter link exists, though, it would contribute not only to explaining and predicting forest mortality but also to interventions to render individual trees more drought resistant. Given that xylem conduits scale with plant height, taller plants have wider conduits. If there is a vulnerability-diameter link, then this would help explain why taller plants are often more vulnerable to climate change-induced drought. Links between conduit diameter, plant height, and vulnerability would also provide guidance for standardizing sampling of hydraulic variables across individuals and suggest that selecting for relatively narrow conduits at given height from the tree top could produce more drought resistant varieties. As a result, given current ambiguities, together with the potential importance of a link, it is important to maintain the vulnerability-diameter link as a research priority.

The contamination of water by per- and polyfluorinated substances (PFAS) is a pressing global issue due to their harmful effects on health and the environment. This study explores a cationic covalent organic framework (COF), TG-PD COF, for the efficient detection and removal of perfluorooctanoic acid (PFOA) from water. Synthesized via a simple sonochemical method, TG-PD COF shows remarkable selectivity and sensitivity to PFOA, with a detection limit as low as 1.8 µg·L⁻¹. It achieves significant PFOA adsorption exceeding 2600 mg·g⁻¹ within seconds over several cycles in batch mode and complete removal at environmentally relevant concentrations in column adsorption. Results reveal unique adsorption behavior characterized by two phases, leveraging PFOA aggregation through hydrophobic interactions. Computer simulations elucidate the mechanisms underlying TG-PD COF’s sensing, adsorption, and charge transfer dynamics. Our findings position this COF design strategy as a promising solution for combating PFAS contamination in water bodies worldwide. The contamination of water by per- and polyfluorinated substances is a pressing global issue. Here, the authors explore a cationic covalent-organic framework for efficient detection and removal of perfluorooctanoic acid (PFOA) from water.