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MAX phases are layered solids with unique properties combining characteristics of ceramics and metals. MXenes are their two‐dimensional siblings that can be synthesized as van der Waals‐stacked and multi‐/single‐layer nanosheets, which possess chemical and physical properties that make them interesting for a plethora of applications. Both families of materials are highly versatile in terms of their chemical composition and theoretical studies suggest that many more members are stable and can be synthesized. This is very intriguing because new combinations of elements, and potentially new structures, can lead to further (tunable) properties. In this review, we focus on the synthesis science (including non‐conventional approaches) and structure of members less investigated, namely compounds with more exotic M‐, A‐, and X‐elements, for example nitrides and (carbo)nitrides, and the related family of MAB phases. This review highlights the breadth of compounds within the families of MAX phases (layered solids) and MXenes (two‐dimensional nanosheets) with a focus on their synthesis science, structure, and less‐explored members, such as (carbo)nitrides.

The US Environmental Protection Agency (EPA) and US Army Corps of Engineers have promulgated a definitional rule to clarify the scope of “waters of the United States” protected under the Clean Water Act (CWA). The Clean Water Rule, published in June 2015, defines 8 categories of waters for jurisdiction and expressly excludes certain features from jurisdiction, based on law, science, public input, and 40+ y of experience implementing the CWA. It also defines terms used in regulation including, for the first time, “tributary,” “neighboring,” and “significant nexus”. Much of the scientific basis for this rule is contained in a report titled “Connectivity of Streams and Wetlands to Downstream Waters: A Review and Synthesis of the Scientific Evidence” developed by EPA’s Office of Research and Development to inform the rulemaking process. As a scientific review, the report does not consider or set forth legal standards for CWA jurisdiction. Rather, it summarizes current scientific understanding of the connections and functions by which small or temporary streams, nontidal wetlands, and other source waters, singly or in aggregate, exert a strong influence on the chemical, physical, or biological integrity of waters protected by the CWA. It is the result of a multiyear collaboration by scientists and nonscientists working across disciplinary and organizational boundaries to synthesize the best available science in response to evolving policy needs. Here I summarize the major conclusions from the report, the influence of science on policy decisions in the final rule, and some challenges of synthesizing, interpreting, reviewing, and communicating the large body of scientific evidence needed for development of this rule.

Scenario studies have emerged as a powerful approach for synthesizing diverse forms of research and for articulating and evaluating alternative socioecological futures. Unlike predictive modeling, scenarios do not attempt to forecast the precise or probable state of any variable at a given point in the future. Instead, comparisons among a set of contrasting scenarios are used to understand the systemic relationships and dynamics of complex socioecological systems and to define a range of possibilities and uncertainties in quantitative and qualitative terms. We describe five examples of scenario studies affiliated with the US Long Term Ecological Research (LTER) Network and evaluate them in terms of their ability to advance the LTER Network's capacity for conducting science, promoting social and ecological science synthesis, and increasing the saliency of research through sustained outreach activities. We conclude with an argument that scenario studies should be advanced programmatically within large socioecological research programs to encourage prescient thinking in an era of unprecedented global change.

This study consists of a reliable process for synthesizing ZnO NPs by green method. Here, Eucalyptus globulus Labill. leaf extract is utilized as an efficient chelating and capping agent for synthesizing ZnO NPs from zinc nitrate hexahydrate salt. The plant ingredients, structure, morphology, thermal behavior, chemical composition and optical properties of ZnO nanoparticles were investigated using several characterization techniques, namely XRD, FE-SEM, EDX, BET, Zeta potential, DLS, differential scanning calorimetry (DSC) analysis, FT-IR analysis and UV–Vis spectroscopy. The UV–Vis and FTIR analysis of Eucalyptus globulus leaf extract verified that this extract is a promising candidate for biosynthesizing ZnO NPs. The XRD spectrum, DLS and the SEM images confirmed the crystallinity and the spherical-shape of the ZnO NPs with an average size between 27 and 35 nm. The band-gap of the ZnO were measured to be around 2.67 eV. Zeta potential and BET analysis showed that, the biosynthesized ZnO NPs possess good stability and the their specific surface area is 23.481 m 2 /g. DSC analysis exhibits two endothermic peaks related to the water evaporation absorbed by the NPs and modification of zinc complex to zinc hydroxide, with a single exothermic peak related to the crystallization of ZnO NPs and degradation of organic materials.

At seven small-group dialogues held across the United States, field natural-resource professionals were asked to describe the toughest problems facing them over the next 10–15 years. Thirty-five problems were identified, spanning all three components of sustainability—ecological, economic, and social. Most were socioeconomic problems related to people’s choices and values. Key science gaps contributing to the problems’ toughness and top investment priorities to fill critical gaps were described. The problems and priorities identified were then compared to ones identified since 1996 by panels of experts who compiled previous national research reports. Field professionals’ views were consistent with the previous findings and illustrated they have detailed, nuanced understandings of the challenges facing them. Top priorities from the dialogues suggest that socioeconomic forces driving ecological changes are poorly understood. Potential mitigation measures will depend on broader interdisciplinary research delving into sciences beyond ecology, such as demographics, sociology, political science, governance, and economics.

Open data and code can be transformative tools in supporting evidence‐informed solutions for stakeholders. Data can take many forms of evidence in the discipline of applied ecology including tables, lists, maps and visualizations to name a few. Endangered and listed species are often a catalyst for research, conservation and planning. Here, a novel, open data set summarizing all the reported diet and prey items for all endangered, terrestrial dryland species listed in central California is provided as a case study. These data highlight the critical need for sharing data rapidly and transparently to support ecological solution science. Systematic review practices were used, data were compiled and the resulting data set was published in an open access, federated data repository using ecological metadata language and FAIR principles. The goal is to show that these data can now be used and analysed by applied ecologists and stakeholders to identify not only the habitat and spatial needs for the endangered species but to widen the conservation protection net to include prey species. Conserving viable habitat with higher likelihoods of prey presence will better support conservation of endangered species, and data describing reported species are a crucial first step. Interactive tables, local species lists and maps are simple tools that can now be developed regionally with open data such as these. Knowledge of prey items that support endangered species within a region is a critical conservation planning tool. This is an example of a scientific synthesis of the relative frequency of reported prey items and collection methods for listed and endangered terrestrial vertebrate species within the central drylands of California.

Biological ion channels have remarkable ion selectivity, permeability and rectification properties, but it is challenging to develop artificial analogues. Here, we report a metal–organic framework-based subnanochannel (MOFSNC) with heterogeneous structure and surface chemistry to achieve these properties. The asymmetrically structured MOFSNC can rapidly conduct K + , Na + and Li + in the subnanometre-to-nanometre channel direction, with conductivities up to three orders of magnitude higher than those of Ca 2+ and Mg 2+ , equivalent to a mono/divalent ion selectivity of 10 3 . Moreover, by varying the pH from 3 to 8 the ion selectivity can be tuned further by a factor of 10 2 to 10 4 . Theoretical simulations indicate that ion–carboxyl interactions substantially reduce the energy barrier for monovalent cations to pass through the MOFSNC, and thus lead to ultrahigh ion selectivity. These findings suggest ways to develop ion selective devices for efficient ion separation, energy reservation and power generation. Here, using an interfacial growth strategy, UiO-66 MOF nanocrystals are asymmetrically embedded into conical pores in a polymer membrane. These pores have a mono/divalent cation selectivity of 10 3 , which can be tuned by pH, and act as ionic rectifiers.

Materials with flat electronic bands often exhibit exotic quantum phenomena owing to strong correlations. An isolated low-energy flat band can be induced in bilayer graphene by simply rotating the layers by 1.1°, resulting in the appearance of gate-tunable superconducting and correlated insulating phases. In this study, we demonstrate that in addition to the twist angle, the interlayer coupling can be varied to precisely tune these phases. We induce superconductivity at a twist angle larger than 1.1°—in which correlated phases are otherwise absent—by varying the interlayer spacing with hydrostatic pressure. Our low-disorder devices reveal details about the superconducting phase diagram and its relationship to the nearby insulator. Our results demonstrate twisted bilayer graphene to be a distinctively tunable platform for exploring correlated states.

The present study aims at investigating the dry sliding wear behavior of Al-based 6082 metal matrix composites (AMMCs) reinforced with red mud particles by pin-on-disc configuration. AMMCs were fabricated with three different weight fractions of red mud particles ranging from 2 to 6% by using the stir-casting method. The friction coefficients and volumetric wear rates were continuously evaluated under normal loads of 10–30 N and sliding speed of 1.5 m s −1 for the constant sliding distance of 1000 m. Microstructural analysis indicated that red mud particles are more or less uniformly dispersed throughout the Al matrix with minimal agglomeration. Experimental data shows that microhardness and tensile strengths of both the as-cast and heat-treated composites are steadily improved by increasing the amount of reinforced red mud particles but at the cost of ductility. Analysis of worn surfaces revealed that delamination and abrasion are dominant wear mechanisms for the case of the heat-treated composites are whereas the adhesion wear mechanism for the base alloy. The composite containing 4% red mud particles experienced the lowest wear rate at a normal load of 30 N and sliding speed of 1.5 m s −1 as compared to other composites including the base alloy. While the composite with 2% red mud particles shows the lowest friction coefficient, base alloy exhibited the highest friction coefficient.

In this present work, the synthesis of g-C 3 N 4 /TiO 2 nanocomposites with different wt.% g-C 3 N 4 to form a type-II heterostructure and its potential application towards photoelectrocatalytic water splitting was discussed. The synthesized g-C 3 N 4 nanoplatelets incorporated TiO 2 nanocomposites were characterized by various analytical techniques such as UV–vis diffuse reflectance spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, photoluminescence spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis and high-resolution transmission electron microscopy (HRTEM). HRTEM confirms the formation of type-II heterostructure consists of g-C 3 N 4 nanoplatelets incorporated titania in the nanocomposite. The photoelectrocatalytic activity of the TiO 2 , g-C 3 N 4 , and g-C 3 N 4 /TiO 2 nanocomposite were investigated under AM 1.5G (100 mW cm −2 ) illumination in 1 M KOH. The g-C 3 N 4 /TiO 2 (with 10 wt.% of g-C 3 N 4 ) nanocomposite photoanode exhibits photocurrent density of 142.7 μA cm −2 (at 1.23 V vs. RHE) which is ~ 1.8-fold higher than bare TiO 2 (80.5 μA cm −2 at 1.23 V vs. RHE). The enhancement in PEC activity explained by formation of type-II heterostructure between g-C 3 N 4 and TiO 2 , which reduced the recombination rate of photo-generated electron–hole pairs and also extends the absorption of TiO 2 to visible light range and boost up the interfacial charge transfer between electrode/electrolyte interface, which enhance the PEC activity of the g-C 3 N 4 /TiO 2 nanocomposite towards water splitting.