Photocatalyzed C3-H Nitrosylation of Imidazo[1,2-a]pyridine under Continuous Flow and External Photocatalyst-, Oxidant-, and Additive-Free Conditions.

This study reports a protocol for the highly regioselective photocatalyzed C-H nitrosylation of imidazo[1,2-a]pyridine scaffolds at the C3 position under a combination of visible-light irradiation and continuous flow without any external photocatalyst. This protocol involves mild and safe conditions and shows good tolerance to air and water along with excellent functional group compatibility and site selectivity, generating various 3-nitrosoimidazo[1,2-a]pyridines in excellent yields under photocatalyst-, oxidant-, and additive-free conditions.Notably, the proposed nitrosylation reaction, which introduces the chromophore NO into imidazo[1,2-a]pyridine scaffolds, occurs efficiently under visible-light irradiation without any additional photocatalyst owing to the intense light-absorption characteristics of the nitrosylation products. This study could guide future studies on the development of green organic-synthesis strategies with a wide variety of potential applications.

Modeling the risk of aquatic species invasion spread through boater movements and river connections.

Aquatic invasive species (AIS) are one of the greatest threats to the functioning of aquatic ecosystems worldwide. Once an invasive species has been introduced to a new region, many governments develop management strategies to reduce further spread. Nevertheless, managing AIS in a new region is challenging because of the vast areas that need protection and limited resources. Spatial heterogeneity in invasion risk is driven by environmental suitability and propagule pressure, which can be used to prioritize locations for surveillance and intervention activities. To better understand invasion risk across aquatic landscapes, we developed a simulation model to estimate the likelihood of a waterbody becoming invaded with an AIS. The model included waterbodies connected via a multilayer network that included boater movements and hydrological connections. In a case study of Minnesota, we used zebra mussels (Dreissena polymorpha) and starry stonewort (Nitellopsis obtusa) as model species. We simulated the impacts of management scenarios developed by stakeholders and created a decision-support tool available through an online application provided as part of the AIS Explorer dashboard. Our baseline model revealed that 89% of new zebra mussel invasions and 84% of new starry stonewort invasions occurred through boater movements, establishing it as a primary pathway of spread and offering insights beyond risk estimates generated by traditional environmental suitability models alone. Our results highlight the critical role of interventions applied to boater movements to reduce AIS dispersal.

Modelo del riesgo de la invasión de especies acuáticas dispersadas por movimiento de botes y conexiones entre ríos Resumen Las especies acuáticas invasoras (EAI) son una de las principales amenazas para el funcionamiento de los ecosistemas acuáticos a nivel mundial. Una vez que una especie invasora ha sido introducida a una nueva región, muchos gobiernos desarrollan estrategias de manejo para disminuir la dispersión. Sin embargo, el manejo de las especies acuáticas invasoras en una nueva región se complica debido a las amplias áreas que necesitan protección y los recursos limitados. La heterogeneidad espacial de un riesgo de invasión es causada por la idoneidad ambiental y la presión de propágulo, que puede usarse para priorizar la ubicación de las actividades de vigilancia e intervención. Desarrollamos una simulación para estimar la probabilidad de que un cuerpo de agua sea invadido por EAI para tener un mejor entendimiento del riesgo de invasión en los paisajes acuáticos. El modelo incluyó cuencas conectadas a través de una red multicapa que incluía movimiento de botes y conexiones hidrológicas. Usamos como especies modelo a Dreissena polymorpha y a Nitellopsis obtusa en un estudio de caso en Minnesota. Simulamos el impacto de los escenarios de manejo desarrollado por los actores y creamos una herramienta de decisiones por medio de una aplicación en línea proporcionada como parte del tablero del Explorer de EAI. Nuestro modelo de línea base reveló que el 89% de las invasiones nuevas de D. polymorpha y el 84% de las de N. obtusa ocurrieron debido al movimiento de los botes, lo que lo estableció como una vía primaria de dispersión y nos proporcionó información más allá de las estimaciones de riesgo generadas por los modelos tradicionales de idoneidad ambiental. Nuestros resultados resaltan el papel crítico de las intervenciones aplicadas al movimiento de los botes para reducir la dispersión de especies acuáticas invasoras.

Ecological niche conservatism spurs diversification in response to climate change.

Lengthy debate has surrounded the theoretical and empirical science of whether climatic niche evolution is related to increased or decreased rates of biological diversification. Because species can persist for thousands to millions of years, these questions cross broad scales of time and space. Thus, short-term experiments may not provide comprehensive understanding of the system, leading to the emergence of contrasting opinions: niche evolution may increase diversity by allowing species to explore and colonize new geographic areas across which they could speciate; or, niche conservatism might augment biodiversity by supporting isolation of populations that may then undergo allopatric speciation. Here, we use a simulation approach to test how biological diversification responds to different rates and modes of niche evolution. We find that niche conservatism promotes biological diversification, whereas labile niches-whether adapting to the conditions available or changing randomly-generally led to slower diversification rates. These novel results provide a framework for understanding how Earth-life interactions produced such a diverse biota.

Modulating the Oxygen Reduction Reaction Performance via Precisely Tuned Reactive Sites in Porphyrin-Based Covalent Organic Frameworks.

Covalent organic frameworks (COFs) have emerged as promising electrocatalysts due to their controllable architectures, highly exposed molecular active sites, and ordered structures. In this study, a series of porphyrin-based COFs (TAPP-x-COF) with various transition metals (Co, Ni, Fe) were synthesized via a facile post-metallization strategy under solvothermal synthesis. The resulting porphyrin-based COFs showed oxygen reduction reaction (ORR) activity with a trend in Co > Fe > Ni. Among them, TAPP-Co-COF exhibited the best ORR activity (E1/2 = 0.66 V and jL = 4.82 mA cm-2) in alkaline media, which is comparable to those of Pt/C under the same conditions. Furthermore, TAPP-Co-COF was employed as a cathode in a Zn-air battery, demonstrating a high power density of 103.73 mW cm-2 and robust cycling stability. This work presents a simple method for using COFs as a smart platform to fabricate efficient electrocatalysts.

Photoactive Covalent Organic Frameworks for Catalyzing Organic Reactions.

Because of their large surface areas, long-range order, π-π stacking interactions and hierarchically integrated building blocks, covalent organic frameworks (COFs) have attracted increasing attention. Recently, COFs have been regarded as promising heterogeneous photocatalysts, owing to their remarkable light-harvesting and energy transition capabilities. The research progress of COFs in photocatalytic organic synthesis is summarized, such as preparation of imines through the oxidation of amines, selective oxidation of sulfides, oxidative hydroxylation of arylboronic acids, C-H bond activation, cyclization, asymmetric organic synthesis and so on. Finally, a perspective of the present challenges of photoactive COFs in organic transformations is given.

Fluorinated covalent organic frameworks for efficient drug delivery.

In this study, two novel fluorine-functionalized crystalline covalent organic frameworks (COFs), namely DF-TAPB-COF and DF-TATB-COF, were synthesized, and their ordered structure, porosity, suitable pore size, and abundant fluorine groups were expected to serve as effective carriers in drug delivery. The excellent cell viability of DF-TAPB-COF and DF-TATB-COF was verified using MTT assays. Both COFs exhibited very high loading capacities in terms of drug loading performance, in particular the drug loading rate of DF-TAPB-COF for 5-fluorouracil (5-FU) was up to 69%. They also exhibited efficient drug release performance in a simulated body fluid environment. Cell endocytosis experiments demonstrated that DF-TAPB-COF and DF-TATB-COF could be effectively endocytosed by cells. Hence, this study offers new insight into the design and development of COF-based drug carrier systems.

Covalent Organic Frameworks with Tailored Functionalities for Modulating Surface Potentials in Triboelectric Nanogenerators.

Designing materials with high triboelectric is an efficient way of improving output performance of triboelectric nanogenerators (TENGs). Herein, we synthesized a series of covalent organic frameworks (COFs) with similar skeletons but various functional groups ranging between electron-donating and electron-withdrawing. These COFs form an ideal platform for clarifying the contribution of each group to TENG performance because the pore wall is perturbed in a predesigned manner. Kelvin probe force microscopy and computational data suggest that surface potentials and electron affinities of COFs can be improved by introducing electron-donating or withdrawing groups, with the highest values observed for fluorinated COF. The TENG with fluorinated COF delivered an output voltage and current of 420 V and 64 µA, respectively, which are comparable to other reported materials. This strategy can be used to efficiently screen suitable frameworks as TENG materials with excellent output performance.

Ecological Niche Shifts Affect the Potential Invasive Risk of Rapistrum rugosum (L.) All. in China.

Ecological niche is a key concept that links species distributions. Ecological niche shifts are expected to affect the potential invasive risk of alien species. Rapistrum rugosum is an invasive agricultural weed in many countries. Wild populations of R. rugosum have been recorded in China, representing a great threat to the regional crops. Based on distribution records from different regions and relevant environmental variables, the present study predicted the potential distribution and estimated the invasive risk of R. rugosum in China. Ecological niche shifts strongly affected the potential invasive risk of R. rugosum in China. The two most important variables were annual temperature range (Bio7) and mean temperature of the coldest quarter (Bio11). The total suitable habitat for the species covered an area of 287.53 × 104km2 and was mainly distributed in Southwest, Southeast, and Central China. Australia, Canada, Brazil, the United States, and Argentina accounted for over 90% of the inspection records of R. rugosum from Chinese entry ports during 2015-2018. The intercepted R. rugosum was frequently mixed in Glycine max (L.) Merr., Hordeum vulgare L., linseed, Triticum aestivum L., and Sorghum bicolor (L.) Moench. Moreover, 80% interceptions were recorded from Tianjin, Guangdong, Nanjing, and Chengdu customs. Climatic conditions do not limit the establishment capability of R. rugosum in China. Our results provide a theoretical reference for the development of monitoring and control measures for this invasive weed.

Design of Photoactive Covalent Organic Frameworks as Heterogeneous Catalyst for Preparation of Thiophosphinates from Phosphine Oxides and Thiols.

Two new covalent organic frameworks (COFs) were synthesized from 4,4',4'',4'''-(pyrene-1,3,6,8-tetrayl)tetraaniline and 2,5-dimethoxyterephthalaldehyde (Py-DMTA-COF) or 2',5'-dimethoxy-[1,1':4',1''-terphenyl]-4,4''-dicarbaldehyde (Py-DMTPDA-COF) under solvothermal conditions. These two COFs were further facilely developed as efficient photocatalytic platforms for the synthesis of thiophosphinates. Py-DMTA-COF exhibited better photocatalytic activity, broad substrate applicability, and excellent recycling capacity for the preparation of thiophosphinates from P(O)H compounds and thiols compared to Py-DMTPDA-COF. This methodology was further extended to the seamless gram-scale production of target phosphorothioate derivatives. The results demonstrate that COFs can provide a robust platform for developing metal-free, base-free, highly efficient, and reusable heterogeneous photocatalysts for organic transformations.

Past climate cooling promoted global dispersal of amphipods from Tian Shan montane lakes to circumboreal lakes.

Climate changes have substantial impacts on the geographic distribution of montane lakes and evolutionary dynamics of cold-adapted species. Past climate cooling is hypothesized to have promoted the dispersal of cold-adapted species via montane lakes, while future climate warming is thought to constrain their distributions. We test this hypothesis by using phylogeographic analysis and niche modeling of the Holarctic crustacean Gammarus lacustris with global sampling comprised of 567 sequenced individuals and 3180 occurrence records. We found that the species arose in Tian Shan in Central Asia and dispersed into montane lakes along the Alps, Himalayas, Tibet, East Asia, and the North American Rocky Mountain ranges, with accelerated diversification rates outside Tian Shan. Climatically suitable regions for geographic lineages of G. lacustris were larger during cooling periods (LGM), but smaller during warming periods (Mid-Holocene). In the future (2070) scenario, potential distributions in the Himalayas, North Tibet, South Tibet and North America are predicted to expand, whereas ranges in East Asia, Europe and Tian Shan will decline. Our results suggest that Mid-Miocene-to-Pleistocene continuous cooling promoted multiple independent dispersal events out of Tian Shan due to increased availability of montane lakes via "budding" of lineages. Montane lakes are conduits through which cold-adapted amphipods globally dispersed, dominating circumboreal lakes. However, future climate warming is likely to force organisms to shift upward in altitude and northward in latitude, leading to a future change in local populations. These findings highlight the importance of conservation of montane lakes, especially in the context of climate change.

A multi-faceted comparative perspective on elevational beta-diversity: the patterns and their causes.

The observed patterns and underlying mechanisms of elevational beta-diversity have been explored intensively, but multi-dimensional comparative studies remain scarce. Herein, across distinct beta-diversity components, dimensions and species groups, we designed a multi-faceted comparative framework aiming to reveal the general rules in the observed patterns and underlying causes of elevational beta-diversity. We have found that: first, the turnover process dominated altitudinal patterns of species beta-diversity (ßsim > ßsne), whereas the nestedness process appeared relatively more important for elevational trait dissimilarity (ßfuncsim < ßfuncsne); second, the taxonomic turnover was relative higher than its phylogenetic and functional analogues (ßsim > ßphylosim/ßfuncsim), conversely, nestedness-resultant trait dissimilarity tended to be higher than the taxonomic and phylogenetic measures (ßfuncsne > ßsne/ßphylosne); and third, as elevational distance increased, the contradicting dynamics of environmental filtering and limiting similarity have jointly led the elevational patterns of beta-diversity, especially at taxonomic dimension. Based on these findings, we infer that the species turnover among phylogenetic relatives sharing similar functional attributes appears to be the main cause of shaping the altitudinal patterns of multi-dimensional beta-diversity. Owing to the methodological limitation in the randomization approach, currently, it remains extremely challenging to distinguish the influence of the neutral process from the offset between opposing niche-based processes. Despite the complexities and uncertainties during species assembling, with a multi-dimensional comparative perspective, this work offers us several important commonalities of elevational beta-diversity dynamics.

The NIH public access policy did not harm biomedical journals.

The United States National Institutes of Health (NIH) imposed a public access policy on all publications for which the research was supported by their grants; the policy was drafted in 2004 and took effect in 2008. The policy is now 11 years old, yet no analysis has been presented to assess whether in fact this largest-scale US-based public access policy affected the vitality of the scholarly publishing enterprise, as manifested in changed mortality or natality rates of biomedical journals. We show here that implementation of the NIH policy was associated with slightly elevated mortality rates and mildly depressed natality rates of biomedical journals, but that birth rates so exceeded death rates that numbers of biomedical journals continued to rise, even in the face of the implementation of such a sweeping public access policy.

Spatio-temporal climate change contributes to latitudinal diversity gradients.

The latitudinal diversity gradient (LDG), where the number of species increases from the poles to the Equator, ranks among the broadest and most notable biodiversity patterns on Earth. The pattern of species-rich tropics relative to species-poor temperate areas has been recognized for well over a century, but the generative mechanisms are still debated vigorously. We use simulations to test whether spatio-temporal climatic changes could generate large-scale patterns of biodiversity as a function of only three biological processes-speciation, extinction and dispersal-omitting adaptive niche evolution, diversity-dependence and coexistence limits. In our simulations, speciation resulted from range disjunctions, whereas extinction occurred when no suitable sites were accessible to species. Simulations generated clear LDGs that closely match empirical LDGs for three major vertebrate groups. Higher tropical diversity primarily resulted from higher low-latitude speciation, driven by spatio-temporal variation in precipitation rather than in temperature. This suggests that spatio-temporal changes in low-latitude precipitation prompted geographical range disjunctions over Earth's history, leading to high rates of allopatric speciation that contributed to LDGs. Overall, we show that major global biodiversity patterns can derive from interactions of species' niches (fixed a priori in our simulations) with dynamic climate across complex, existing landscapes, without invoking biotic interactions or niche-related adaptations.

Hydrangea-like α-Ni1/3Co2/3(OH)2 Reinforced by Ethyl Carbamate "Rivet" for All-Solid-State Supercapacitors with Outstanding Comprehensive Performance.

Improving the self-conductivity and structural stability of electrode materials is a key strategy to improve the energy density, rate performance, and cycle life of supercapacitors. Controlled intercalation of ethyl carbamate (CH3CH2OCONH2) as the rivet between Ni-Co hydroxide layers can be used to obtain sufficient ion transport channels and robust structural stability of hydrangea-like α-Ni1/3Co2/3(OH)2 (NC). Combining the improved electronic conductivity offered by the coexistence of Ni2+ and Co2+ optimizing itself electronic conductivity and the addition of carbon nanotubes (CNTs) as the electron transport bridge between the active material and the current collector and the large specific surface area (296 m2 g-1) reducing the concentration polarization, the capacitance retention ratio of NC-CNT from 0.2 to 20 A g-1 is up to 93.4% and its specific capacitance is as high as 1228.7 F g-1 at 20 A g-1. The large total hole volume (0.40 cm3 g-1) and wide crystal plane spacing (0.71 nm) provide an adequate space to withstand structure deformation during charge/discharge processes and enhance the structural stability of the NC material. The capacitance fading ratio of NC-CNT is only 4.5% at 10 A g-1 for 10 000 cycles. The aqueous supercapacitor (NC-CNT//AC) and all-solid-state supercapacitor (PVA-NC-CNT//PVA-AC) exhibit high energy density (35.2 W h kg-1 at 100.0 W kg-1 and 35.4 W h kg-1 at 100.7 W kg-1), ultrahigh rate performance (the specific capacitances at 20 A g-1 are 92.8 and 87.2% compared to that at 0.5 A g-1), and long cycling life span (the specific capacitances after 100 000 cycles at 10 A g-1 are 91.5 and 90.8% compared with that of their initial specific capacitances), respectively. Therefore, hydrangea-like NC could be a promising material for advanced next-generation supercapacitors.

Ecological niche modeling re-examined: A case study with the Darwin's fox.

Many previous studies have attempted to assess ecological niche modeling performance using receiver operating characteristic (ROC) approaches, even though diverse problems with this metric have been pointed out in the literature. We explored different evaluation metrics based on independent testing data using the Darwin's Fox (Lycalopex fulvipes) as a detailed case in point. Six ecological niche models (ENMs; generalized linear models, boosted regression trees, Maxent, GARP, multivariable kernel density estimation, and NicheA) were explored and tested using six evaluation metrics (partial ROC, Akaike information criterion, omission rate, cumulative binomial probability), including two novel metrics to quantify model extrapolation versus interpolation (E-space index I) and extent of extrapolation versus Jaccard similarity (E-space index II). Different ENMs showed diverse and mixed performance, depending on the evaluation metric used. Because ENMs performed differently according to the evaluation metric employed, model selection should be based on the data available, assumptions necessary, and the particular research question. The typical ROC AUC evaluation approach should be discontinued when only presence data are available, and evaluations in environmental dimensions should be adopted as part of the toolkit of ENM researchers. Our results suggest that selecting Maxent ENM based solely on previous reports of its performance is a questionable practice. Instead, model comparisons, including diverse algorithms and parameterizations, should be the sine qua non for every study using ecological niche modeling. ENM evaluations should be developed using metrics that assess desired model characteristics instead of single measurement of fit between model and data. The metrics proposed herein that assess model performance in environmental space (i.e., E-space indices I and II) may complement current methods for ENM evaluation.

Summary results of the 2014-2015 DARPA Chikungunya challenge.

BACKGROUND: Emerging pathogens such as Zika, chikungunya, Ebola, and dengue viruses are serious threats to national and global health security. Accurate forecasts of emerging epidemics and their severity are critical to minimizing subsequent mortality, morbidity, and economic loss. The recent introduction of chikungunya and Zika virus to the Americas underscores the need for better methods for disease surveillance and forecasting. METHODS: To explore the suitability of current approaches to forecasting emerging diseases, the Defense Advanced Research Projects Agency (DARPA) launched the 2014-2015 DARPA Chikungunya Challenge to forecast the number of cases and spread of chikungunya disease in the Americas. Challenge participants (n=38 during final evaluation) provided predictions of chikungunya epidemics across the Americas for a six-month period, from September 1, 2014 to February 16, 2015, to be evaluated by comparison with incidence data reported to the Pan American Health Organization (PAHO). This manuscript presents an overview of the challenge and a summary of the approaches used by the winners. RESULTS: Participant submissions were evaluated by a team of non-competing government subject matter experts based on numerical accuracy and methodology. Although this manuscript does not include in-depth analyses of the results, cursory analyses suggest that simpler models appear to outperform more complex approaches that included, for example, demographic information and transportation dynamics, due to the reporting biases, which can be implicitly captured in statistical models. Mosquito-dynamics, population specific information, and dengue-specific information correlated best with prediction accuracy. CONCLUSION: We conclude that with careful consideration and understanding of the relative advantages and disadvantages of particular methods, implementation of an effective prediction system is feasible. However, there is a need to improve the quality of the data in order to more accurately predict the course of epidemics.

Silver(I)-Catalyzed C4-H Amination of 1-Naphthylamine Derivatives with Azodicarboxylates.

A simple and efficient protocol for silver(I)-catalyzed picolinamide directed C4-H amination of 1-naphthylamine derivatives with readily available azodicarboxylates has been developed, demonstrating a new approach to 1,4-naphthalenediamine derivatives in high yields. Note that this reaction system could proceed under external-oxidant- and additive-free conditions (only requires 5 mol % of AgOAc as the catalyst in acetone).

Ru/Cu Photoredox or Cu/Ag Catalyzed C4-H Sulfonylation of 1-Naphthylamides at Room Temperature.

A mild and efficient protocol for C4-H sulfonylation of 1-naphthylamine derivatives with sodium sulfinates has been described. This C4 sulfonylation proceeded smoothly at room temperature under Ru/Cu photoredox catalysis or Cu/Ag cocatalysis and could tolerate various functional groups. In addition, control experiments suggested that this C4-H sulfonylation reaction might proceed via a single-electron-transfer process.

Novel Methods in Disease Biogeography: A Case Study with Heterosporosis.

Disease biogeography is currently a promising field to complement epidemiology, and ecological niche modeling theory and methods are a key component. Therefore, applying the concepts and tools from ecological niche modeling to disease biogeography and epidemiology will provide biologically sound and analytically robust descriptive and predictive analyses of disease distributions. As a case study, we explored the ecologically important fish disease Heterosporosis, a relatively poorly understood disease caused by the intracellular microsporidian parasite Heterosporis sutherlandae. We explored two novel ecological niche modeling methods, the minimum-volume ellipsoid (MVE) and the Marble algorithm, which were used to reconstruct the fundamental and the realized ecological niche of H. sutherlandae, respectively. Additionally, we assessed how the management of occurrence reports can impact the output of the models. Ecological niche models were able to reconstruct a proxy of the fundamental and realized niche for this aquatic parasite, identifying specific areas suitable for Heterosporosis. We found that the conceptual and methodological advances in ecological niche modeling provide accessible tools to update the current practices of spatial epidemiology. However, careful data curation and a detailed understanding of the algorithm employed are critical for a clear definition of the assumptions implicit in the modeling process and to ensure biologically sound forecasts. In this paper, we show how sensitive MVE is to the input data, while Marble algorithm may provide detailed forecasts with a minimum of parameters. We showed that exploring algorithms of different natures such as environmental clusters, climatic envelopes, and logistic regressions (e.g., Marble, MVE, and Maxent) provide different scenarios of potential distribution. Thus, no single algorithm should be used for disease mapping. Instead, different algorithms should be employed for a more informed and complete understanding of the pathogen or parasite in question.