Mapping Brittle and Ductile Behaviors of Polymeric Glasses under Large Extension

We have carried out a series of tensile extension tests on the two most common polymer glasses to describe their generic mechanical responses as a function of deformation rate at different temperatures. The essentially defect-free polystyrene and poly­(methyl methacrylate) both show remarkable re-entrant failure: being ductile at intermediate rates and showing diminishing toughness at both higher and lower rates. We draw phase diagrams to map out the relationship between brittle-like and yield-like states in terms of temperature, rate, and stress. A coherent understanding of the rich phenomenology requires us to describe in more detail the interplay between the chain network and the primary structure bonded by intersegmental van der Waals forces

Establishing the relationship between urban land-cover configuration and night time land-surface temperature using spatial regression

Studies suggest that urban form can influence microclimate regulation. Remote sensing studies have contributed to these findings through analysis of high-resolution land cover maps, landscape ecology metrics, and thermal imagery. Collectively, these have been referred to as land cover configuration studies. There are three objectives to this study. The first is to assess the relationship between nighttime land surface temperatures (LST) and land cover configuration and composition. The second objective is to outline a comprehensive methodology that includes ordinary least squares (OLS), spatial regression, variable selection, and multicollinearity analysis. Our last objective is to test three hypotheses about the relationship between LST and land cover, which can briefly be described as: 1) the importance of land-use regimes in modeling LST from land cover composition and configuration variables; 2) the strength of the correlation between LST and roads, buildings, and vegetation; and 3) the improved quality of models using landscape metrics in modeling the relationship between LST and land cover. Based on 16 different models (8 OLS, 8 spatial regression) we could confirm the above hypotheses, but we found that the configuration of buildings, roads, and vegetation have a complex relationship with LST. Our interpretation of this complexity, combined with the strength of composition variables, is that parsimonious models, for now, are more useful to urban planners because they are more generalizable. Finally, spatial regression models of land cover configuration and LST demonstrated an improvement over non-spatial linear models (OLS). Spatial regression models reduced heteroskedasticity and clusters of residuals, and tempered coefficients, suggesting that the OLS models could be biased. OLS models were still found to be a valuable tool for exploratory analysis.</p

Metal–Organic Framework Structure with Fe–Co–Se (MIL-88A/Fe–Co@Se) as a Cathode for Aluminum Batteries

Rechargeable aluminum-ion batteries have received more and more attention because of their high theoretical energy density, high safety, and reasonable price. The cathode material of aluminum batteries is one of the key bottlenecks that limits their development. Although there are many reports on aluminum battery cathode materials, many of these reports fail to simultaneously solve the poor cycling stability and low specific capacity of aluminum batteries. Therefore, we formed YSNT@Se hybrids by compounding the MOFsMIL-88A@Fe–Co hydroxide yolk–shell nanotubes (YSNTs) with selenium for the first time. It was finally determined that the FeSe2 in YSNT@Se is the main redox reaction participant during charging/discharging. In the charge/discharge of YSNT@Se 500 °C, it achieved a first cycle discharge specific capacity of 292.21 mA h g–1. After 500 cycles, the discharge capacity was 233.34 mA h g–1 and the capacity retention rate reached 79.85%. This result proves that the redox process is highly reversible at the same time. This work makes it possible for aluminum batteries to have a high cycling performance and a high capacity and broadens the research direction of cathode materials for aluminum batteries

DataSheet1_Temporal changes of the food web structure and function driven by changes in hydrological regimes and water quality in a large shallow lake.docx

Assessing food web structural properties and energy fluxes under changing hydrological regimes and water quality reveals the temporal patterns of ecosystem dynamics in shallow lakes. Here, we studied northern China’s largest shallow lake (Lake Baiyangdian) using quantitative food web models for five representative years (1958, 1980, 1993, 2009, and 2019). We analyzed the temporal patterns of food web structure and function by combining a Bayesian isotope mixing model with a food web energetics model. We further examined the temporal changes of unweighted and weighted food web topological attributes. Lake Baiyangdian changed from a detritus-based into a phytoplankton-based food web based on the relative contributions of basal food sources and energy flux distributions. The trophic position of fingerlings, large omnivorous fish, and carnivorous fish decreased with increasing eutrophication. The highest energy fluxes were from detritus to zooplankton and mollusks in 1958, from detritus and phytoplankton to zooplankton in 1980, 1993, and 2009, and from phytoplankton to zooplankton and detritus to mollusks in 2019. The highest total energy flux was in 1993, followed by 2019, with the lowest value in 1958. Unweighted food web metrics showed similar patterns. We observed more pronounced temporal variability in the node- and link-weighted food web metrics than in the unweighted metrics. In addition, hydrological factors (threshold, duration, reversals between high, and low water levels), eutrophication, and some water quality factors (chemical oxygen demand, dissolved oxygen, and pH) played important roles in the temporal changes of food web dynamics in Lake Baiyangdian. Our findings demonstrate the importance of integrating unweighted and weighted indicators to holistically comprehend how highly aggregated food webs respond to changing hydrological regimes and water quality, thereby improving management and restoration of shallow lake ecosystems.</p

sj-docx-1-sgo-10.1177_21582440221085270 – Supplemental material for Biosafety Management Risk Analysis for Clinical Departments of Military Central Hospitals in the Fujian Province of China

Supplemental material, sj-docx-1-sgo-10.1177_21582440221085270 for Biosafety Management Risk Analysis for Clinical Departments of Military Central Hospitals in the Fujian Province of China by Xiaoxiao Li, Maihong He, Xian Lin and Ying Lin in SAGE Open</p

DataSheet_1_Trophic Diversity and Food Web Structure of Vegetated Habitats Along a Coastal Topographic Gradient.docx

Land–sea interactions in coastal wetlands create heterogeneous vegetated habitats with regular zonation along a topographic gradient. However, it’s unclear how the trophic diversity of communities and trophic structure of food webs change along the gradient. Here, we investigated the empirically resolved food web structure and trophic diversity across four vegetated habitats (Phragmites australis, Suaeda salsa, Spartina alterniflora, and Zostera japonica seagrass) along a gradient from upland to near-shore waters in the Yellow River Delta wetland. We quantified δ13C and δ15N of carbon sources (detritus, primary producers) and consumers (zooplankton, macroinvertebrates, fish). δ13C and δ15N of the carbon sources and consumers differed significantly among the four habitats. Carbon sources and consumers became more 13C-enriched and 15N-enriched along the gradient, respectively. The consumer trophic position was higher in the S. salsa habitat than in the seagrass habitat, followed by the S. alterniflora and P. australis habitats. The habitat formed by invasive S. alterniflora had the lowest corrected standard ellipse areas in the δ13C vs. δ15N plots for the basal carbon sources and all consumers combined, and the lowest Layman community metrics for the δ13C range, total area, and centroid distance; thus, trophic groups in this habitat had the lowest isotopic trophic diversity. Using a Bayesian isotope mixing model, we found that consumer diet compositions differed greatly among the habitats where the consumer was present, except for shrimps and polychaetes. Food web topological properties (species richness, number of trophic links, linkage density, proportions of intermediate consumers and omnivores) increased along the gradient. Generally, habitat heterogeneity created highly variable food webs. Our results provide insights into the spatial variation in coastal ecosystems along a topographic gradient, and demonstrate the need to protect habitat heterogeneity in coastal wetlands, combined with adaptive management to control invasive species.</p

Metal-Free C–H Functionalization of Allenamides: An Access to Branched Allylic Esters

A regioselective acyloxylation with carboxylic acids at the proximal carbon of allenamides by an N-iodosuccinimide-mediated C–H functionalization is reported. The reaction proceeds rapidly, is scalable to a gram scale, and displays a broad substrate scope, providing an efficient and practical protocol for the synthesis of branched allylic esters. Notably, protected amino acids were tolerated under the reaction conditions and afforded allylic amino acid esters in moderate yields

PhI(OAc)₂‑Mediated Regioselective Hydrothiolation of Allenamides with Thiophenol via a Radical Process: Synthesis of Vinyl Sulfides

An efficient PhI­(OAc)2-mediated regioselective hydrothiolation of allenamides with thiophenol via a radical process was developed to create a workable route to vinyl sulfides. The reaction exhibits a good functional group tolerance and high efficiency, affording the products in good to excellent yields. Mechanistic investigations indicated that the radical cascade proceeds through an allyl radical intermediate, which is formed via the addition of the PhS radical to the central carbon of allenamides. Moreover, the reaction was also efficient with selenophenol, providing the corresponding product, vinyl selenide, in a 99% yield

Mutations in Amino Acid Residues of Limosilactobacillus reuteri 121 GtfB 4,6-α-Glucanotransferase that Affect Reaction and Product Specificity

Limosilactobacillus reuteri 121 4,6-α-glucanotransferase (Lr121 4,6-α-GTase), belonging to the glycosyl hydrolase (GH) 70 GtfB subfamily, converts starch and maltodextrins into linear isomalto/malto polysaccharides (IMMPs) with consecutive (α1 → 6) linkages. The recent elucidation of its crystal structure allowed identification and analysis of further structural features that determine its reaction and product specificity. Herein, sequence alignments between GtfB enzymes with different product linkage specificities (4,6-α-GTase and 4,3-α-GTase) identified amino acid residues in GH70 homology motifs, which may be critical for reaction and product specificity. Based on these alignments, four Lr121 GtfB-ΔN mutants (I1020M, S1057P, H1056G, and Q1126I) were constructed. Compared to wild-type Lr121 GtfB-ΔN, mutants S1057P and Q1126I had considerably improved catalytic efficiencies. Mutants H1056G and Q1126I showed a 9% decrease and an 11% increase, respectively, in the ratio of (α1 → 6) over (α1 → 4) linkages in maltodextrin-derived products. A change in linkage type (e.g., (α1 → 6) linkages to (α1 → 3) linkages) was not observed. The possible functional roles of these Lr121 GtfB-ΔN residues located around the acceptor substrate-binding subsites are discussed. The results provide new insights into structural determinants of the reaction and product specificity of Lr121 GtfB 4,6-α-GTase

Facile Synthesis of Nickel–Iron/Nanocarbon Hybrids as Advanced Electrocatalysts for Efficient Water Splitting

Developing active, stable, and low-cost electrocatalysts which can promote the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in the same electrolyte is undoubtedly a vital progress toward a hydrogen economy. Herein, we report that such electrocatalysts can be easily prepared by pyrolyzing a precursor composed of nickel and iron salts with urea under inert atmospheres without any post-treatments. The obtained products are composed of metallic nickel–iron alloy nanoparticles either encapsulated in or dispersed on nitrogen-doped bamboo-like carbon nanotubes (CNTs). This simple synthesis route could simultaneously realize nanostructuring, doping, and hybridizing with nanocarbon, which have been demonstrated as efficient strategies to optimize the catalytic activity of an electrocatalyst. The in situ formed hybrid catalysts exhibit good catalytic performances for both OER and HER under alkaline conditions, and the doping content of iron significantly affects the activities. When the best electrocatalyst is loaded on nickel foam with a loading of 2 mg cm^–2, a symmetric two-electrode cell can execute overall water splitting at a current density of 10 mA cm^–2 with only 1.58 V and shows negligible degradation after 24 h of operation. The excellent electrocatalytic activity and facile preparation method enable this hybrid electrocatalyst to be a promising candidate for future large-scale applications in water splitting