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A cloud computing multi-objective task scheduling optimization based on fuzzy self-defense algorithm is proposed. Select the shortest time, the degree of resource load balance and the cost of multi-objective task completion as the goal of cloud computing multi-objective task scheduling, establish a mathematical model to measure the effect of multi-objective task scheduling, and construct the objective function of cloud computing multi-objective task scheduling. The experimental results show that the cloud computing multi-objective task scheduling optimization method based on fuzzy self-defense algorithm can improve the performance of multi-objective maximum completion time, deadline violation rate and virtual machine resource utilization.

Boroles are attracting broad interest for their myriad and diverse applications, including in synthesis, small molecule activation and functional materials. Their properties and reactivity are closely linked to the cyclic conjugated diene system, which has been shown to participate in cycloaddition reactions, such as the Diels‐Alder reaction with alkynes. The reaction steps leading to boranorbornadienes, borepins and tricyclic boracyclohexenes from the thermal reaction of boroles with alkynes are seemingly well understood as judged from the literature. Herein, we question the long‐established mechanistic picture of pericyclic rearrangements by demonstrating that seven‐membered borepins (i. e., heptaphenylborepin and two derivatives substituted with a thienyl and chloride substituent on boron) exist in a dynamic equilibrium with the corresponding bicyclic boranorbornadienes, the direct Diels‐Alder products, but are not isolable products from the reactions. Heating gradually converts the isomeric mixtures into fluorescent tricyclic boracyclohexenes, the most stable isomers in the series. Results from mechanistic DFT calculations reveal that the tricyclic compounds derive from the boranorbornadienes and not the borepins, which were previously believed to be intermediates in purely pericyclic processes., New insights into the reactivity of perarylated boroles toward alkynes have been derived from both experimental and computational studies. It is shown that borepins (the formal alkyne insertion products) can readily isomerize to the thermodynamically more favorable boranorbornadienes (the formal Diels‐Alder products), thus obscuring the mechanism of product formation (see Figure). In addition, the fluorescent nature of the tricyclic boracyclohexenes, the most stable isomers of the addition reactions, has been investigated by absorption and emission spectroscopy.

Owing to an empty p orbital and a lone pair of electrons on the Si center, silylene exhibits reactivity similar to a transition-metal system capable of activating H2/C-H bonds and small molecules. In this work, with the aid of density functional theory calculations, we systematically investigated the reactions of an acyclic silylene with CO, CO2, and N2O. The detailed mechanisms obtained lead to an in-depth understanding of the silylene single-site ambiphilic reactivity.

Transition metal–boryl complexes play an important role as reactive intermediates in catalytic borylation processes and have enjoyed tremendous exploration. Over the years, it has been well establi...

Biomimetic modularization and function-oriented synthesis of structurally diversified natural product-like macrocycles in a step-economical fashion is highly desirable. Inspired by marine furanocembranoids, herein, we synthesize diverse alkenes substituted furan-embedded macrolactams via a modular biomimetic assembly strategy. The success of this assembly is the development of crucial Pd-catalyzed carbene coupling between ene-yne-ketones as donor/donor carbene precursors and unactivated Csp3‒H bonds which represents a great challenge in organic synthesis. Notably, this method not only obviates the use of unstable, explosive, and toxic diazo compounds, but also can be amenable to allenyl ketones carbene precursors. DFT calculations demonstrate that a formal 1,4-Pd shift could be involved in the mechanism. Moreover, the collected furanocembranoids-like macrolactams show significant anti-inflammatory activities against TNF-α, IL-6, and IL-1β and the cytotoxicity is comparable to Dexamethasone.

The rhodium-catalyzed deoxygenation and borylation of ketones with B2pin2 have been developed, leading to efficient formation of alkenes, vinylboronates, and vinyldiboronates. These reactions feature mild reaction conditions, a broad substrate scope, and excellent functional-group compatibility. Mechanistic studies support that the ketones initially undergo a Rh-catalyzed deoxygenation to give alkenes via boron enolate intermediates, and the subsequent Rh-catalyzed dehydrogenative borylation of alkenes leads to the formation of vinylboronates and diboration products, which is also supported by density functional theory calculations.

[(η6-p-cymene)OsI2]2 was found to be a good catalyst for the cyclopropanation reaction of isobutyl vinyl ether with 3-tert-butyldiazoindene. In contrast, the complexes [(η6-p-cymene)OsX2]2 (X = Cl,...

Highly-efficient and eco-friendly materials and technologies are urgently needed to meet the requirements of nowadays green development. Photocatalysis with using solar energy and enzymatic catalysis with eco-friendly nature are effective alternatives to address the problem. Notably, beneficial use of the synergistic effect of artificial enzyme and advanced photocatalyst has attracted wide attention. This work presents a biomimetic photocatalytic material, two-dimensional (2D) biomimetic hemin-bismuth tungstate (HBWO). Stable HBWO composites formed by immobilization of monomeric hemin on 2D bismuth tungstate layer, exhibit high photocatalytic performance, better than that of pure 2D bismuth tungstate and unsupported hemin. HBWO shows layered structure with the interlayer spacing at ˜0.35 nm. In the photocatalytic process, hemin can not only act as an electron shuttle, also play an important role in oxygen transfer. Additionally, the synthesized HBWO composites exhibit nice binding affinities and high photocatalytic activity in tetracycline degradation. It is anticipated that beneficial use of synergistic effect of artificial enzyme and photocatalyst via HBWO composites can be a promising eco-friendly and efficient solution for addressing the environmental crisis.

Norfloxacin (NOR) in milk may influence mammalian cell replication and bring about a decrease in the efficiency for treating infection in humans. However, current techniques for detecting NOR usually require expensive instruments and trained personnel. In this work, we have developed a low-cost and simple method via paper-based fluorescent immunoassay for highly sensitive and selective detection of NOR in milk at picogram level. The NOR monoclonal antibody labeled with quantum dots is used as a detection probe to recognize the corresponding NOR, which can quantitatively detect NOR on paper-based devices. The detection limits in aqueous solution and milk are 1 pg/mL and 10 pg/mL, respectively. The developed paper-based method provides a cheap, sensitive, eco-friendly, and rapid approach for quantitative detection of trace NOR in milk, which may find wide applications in food safety inspection. Noteworthy, the method is especially suitable for applications at resource-limited and on-site settings.

Biochar, a green material that possesses high catalytic potential due to its persistent free radicals (PFRs), has attracted increasing attention in the removal of refractory pollutants from water. The influences of biomass types (bamboo, corn stalk, and pig manure) and its compositions (metals and phenolic compounds) on the formation of PFRs in biochar were investigated by electron paramagnetic resonance (EPR). It was found that the amounts of PFRs in biochar would decrease sharply with the decrease of the initial metals and phenolic compounds existed in biomass, and the effect of metals contents on PFRs formation was much greater than that of phenolic compounds contents. This finding was supported by the results obtained from elemental analysis and molar H/C analysis of three types of biochar, which suggested that pig-manure biochar (PM500) had the highest concentrations of PFRs of 14.13 × 1018 spins·g−1 due to the high content of metals and phenolic compounds in pig manure. The EPR trapping experiment and Linear sweep voltammetry (LSV) measurements in biochar/H2O2 systems showed that OH was the dominant reactive radical and electrons transfer pathways might be responsible for the activation of H2O2 by biochar. Possible degradation pathways of the tetracycline in biochar/H2O2 systems were also proposed. Besides, high degradation efficiency and good stability were observed in real wastewater application of the PM500/H2O2 system. These findings would provide a clearer insight into the formation mechanisms of PFRs in biochar, and also present a better strategy for biochar preparation and application in Fenton-like system.

Nowadays, Nano-biotechnology is emerging to be one of the most promising tools in environmental remediation. In this study, the degradation efficiency of lignocellulose by white-rot fungi was improved by addition of Fe3O4 nanomaterials (NMs) in solid-state fermentation. The highly-ordered cellulose crystalline was demonstrated to be broken down through infrared spectroscopy (FT-IR) and crystallinity index analysis. The decay of fluorescence intensity presented a lower degree of aromatic polycondensation and less conjugated chromophores in lignocellulose. Mechanistic analysis showed that NMs participated in the Fenton reaction and affected lignocellulose biodegradation process by regulating enzyme secretion. Specifically, the time variation curves of hydroxyl radicals and Fe2+ were discussed to illustrate the degradation pattern. The NMs remained stable after the fermentation and were possible to be recycled for the next cycle. All the results support that the synergism of Fe3O4 NMs and white-rot fungi would be a promising research direction in lignocellulose treatment.

Bismuth tungstate with different structures and morphologies show different properties. The structure and morphology have been proven to be critical factors to tune the electronic properties to influence photocatalytic performance. Notably, nano-structured bismuth tungstate were found to exhibit high activity in photocatalytic degradation process. Controllable fabrication on nano structures with desired morphology is indispensable to achieve the related properties well. However, a review that declare the correlation between the property and the fabrication, structure and morphology of bismuth tungstate is still absent. Therefore, we firstly summarize a series of recent fabrication methods for various dimensional nano structures of bismuth tungstate. Then the modification of nano-structured BWO to improve the photocatalytic performance are presented, including morphological manipulation, doping or substitution, solid solution fabrication, and compound formation. The mechanism of photocatalytic oxidation and reduction process over nano-structured bismuth tungstate is also explored, especially the role of radical species. Additionally, advanced environmental application are summarized. Finally, unresolved challenges and potential applications of nano-structured bismuth tungstate are presented for future research directions.

Density functional theory calculations have been performed to study the diverse reactivity of pentaphenylborole toward different epoxides. We systematically investigated the effect of substituents on epoxides for the preference/competition of three experimentally observed pathways, that is, intramolecular proton transfer, direct ring expansion via insertion of one epoxide molecule, and ring expansion via insertion of two epoxide molecules. Our calculations also predicted a high competitivity between the proton transfer and direct ring expansion pathways for the epoxide containing both alkyl and aryl substituents.

The Qinghai-Tibet Plateau sensu lato (QTP s.l.) harbors an exceptionally high biodiversity, especially at its southeastern margin: this area encompasses the Hengduan Mountains and the eastern Himalayas, which have been listed as biodiversity hotspots. To the contrary, the plateau interior (namely the Qinghai-Tibet Plateau sensu stricto, QTP s.s.) is relatively species-poor because of its particularly harsh climate. With contrasting geological histories and environmental conditions of the Hengduan Mountains, the Himalayas and the QTP s.s., it would be expected that floristic compositions and diversity patterns of these three regions would differ between each other. To compare the floristic diversity of these three regions, we assembled data on seed plant’s distribution in the three regions based on county-level mapping from published monographs and online databases, and we then analyzed their floristic features and species diversity patterns (horizontal and elevational). We found that the Hengduan Mountains hosted the most seed plant species (8,439), as expected. The highest percentage of shrub (22.88%) and tree species (9.80%) were in the Himalayas, whereas herbaceous species (81.50%) were relatively more prominent in the QTP s.s.. The Hengduan Mountains also had the most species-rich genera (10) with more than 50% of their total species diversity in China. Also, temperate genera dominated across these three regions, with a highest percentage (77.61%) within the QTP s.s.. Across the QTP s.l., species diversity gradually decreased from the southeastern part to the northwest, and most of seed plants were distributed in the southern and eastern margin of the Hengduan Mountains and East Himalayas. Along elevational gradients, species richness all demonstrated a hump-shape curve, but the most species-rich elevation zone differed for each type of life-form across the three regions. Our study sets a base for exploring the origin and evolution of mountain taxa, as well as provides a snapshot of the current plant distribution, which will certainly be modified by climate change.

The 4-coordinated RuII chalcogenolate complexes [Ru(STipp)2(PPh3)2] (Tipp = 2,4,6-triisopropylphenyl, 1) and [Ru(SeMes)2(PPh3)2] (Mes = 2,4,6-trimethylphenyl, 2) have been synthesized, and their reactions with PhICl2 and organic azides have been studied. Complex 2 synthesized from [RuII(PPh3)3Cl2] and NaSeMes displays a seesaw structure with P–Ru–P and Se–Ru–Se bond angles of 103.43(13) and 145.26(6)°, respectively. Natural bond order analyses revealed that in each of 1 and 2, there are two n → σ* (donor–acceptor) π interactions between the chalcogen lone pairs and the Ru–P antibonding molecular orbitals. The calculated second-order perturbation interaction energies of the two interactions for 1 (20.5 and 18.3 kcal mol−1) are stronger than those of 2 (13.6 and 11.0 kcal mol−1), suggesting the thiolate ligand (TippS−) is a stronger π-donor than the selenolate ligand (MesSe−) with respect to RuII. Chlorination of 1 with PhICl2 afforded the dichloride complex [Ru(STipp)2Cl2(PPh3)] (3), which was hydrolyzed to the hydroxo complex [Ru(STipp)2(OH)Cl(PPh3)] (4) after column chromatography on silica in air. Treatment of 4 with HCl and methyl triflate gave 3 and [Ru(STipp)2(OH)(OTf)(PPh3)] (OTf = triflate, 5), respectively. Reactions of 1 and 2 with p-tolyl azide (p-tolN3) afforded the tetrazene complexes [Ru{N4(p-tol)2}(ER)2(PPh3)] (ER = STipp (6), SeMes (7)), whereas that with tosyl azide (TsN3) gave the imido complexes [Ru(κ2-NTs)(STipp)2(PPh3)] (ER = STipp (8), SeMes (10)). The short Ru–Nimido distances in 8 [1.883(3) A] and 10 [1.892(2) A] are indicative of multiple bond character. Treatment of 8 with TsN3 afforded the tetrazene complex [Ru(N4Ts2)(STipp)2(PPh3)] (9), but no cycloaddition was found between 10 and TsN3. Nucleophilic attack of the imido ligand in 10 with methyl triflate yielded the amido complex [Ru(κ2-NMeTs)(SeMes)2(PPh3)](OTf) (11). The crystal structures of 2, 4, 6, and 8–11 have been determined.

Composting is an economic and effective technology for solid waste treatment, which is an essential method to promote the biogeochemical cycle of contaminants. However, the application of this technology was limited by the bio-degradative recalcitrance of lignin and other kind of phytotoxic substances release. The combination with microorganisms and enzymes is a popular and efficient way to enhanced composting. This study, referring to metabolic mechanisms, fungal molecular and biogeochemical cycles, was performed to investigate the effects of lignin degradation, carbon metabolic diversity, as well as the related changes induced by these two kinds of complex enzymes in composting. The biological diversity is important indicator in ecosystem, which concerns the environmental applicability of one technology. The carbon metabolism diversity reflected the biogeochemical cycles of organic matter, which was also an essential input to analyze the effects of composting. The changes on the diversity characteristics of carbon are essential to comprehensively understand the deep mechanisms of this process, and extended the application of complex enzymes in the field of enhanced composting. The analysis of Biolog revealed that the utilization of pyruvic acid methyl ester, α-Cyclodextrin, d -Mannitol, d -Galacturonic, Itaconic acid and l -asparagine were deeply promoted, and that of d , l -α-Glycerol-phosphate, l -Threonine, Glycyl- l -Glutamic acid and putrescine were depressed by adding the complex enzyme in composting. Moreover, according to the data, the addition of complex enzymes improved the degradation efficiency and the metabolic capacity of carbon in composting. These findings undoubtedly contribute to the development of enzyme-based technologies and the applications of complex enzymes in composting, which is of great benefit to eliminate the limitation and extend the application of composting.

Highly-efficient materials and technologies for environmental pollutant treatment and hydrogen production are urgently needed in "green" 21st century. Notably, photocatalytic process over carbon nanomaterials (CNMs)-modified photocatalysts is an effective solution for these crises. CNMs (e.g., fullerenes, carbon nanotubes, graphene, carbon nanofibers, and carbon quantum dots) reveal remarkable morphological, mechanical, electrical and optical properties, which have been of significantly scientific and technological interest in photocatalysis. Until now, many efforts have been made to take advantage of these unique size- and surface-dependent properties of CNMs for photocatalytic process. In this review, we firstly summarize selective preparation of CNMs that has a great impact on their photocatalytic performance. Then we provide an updated outline of advanced photocatalytic application of CNMs in addressing both environmental pollution and hydrogen energy crisis. The difference in the role of various CNMs play in the enhancement of photocatalytic performance is also discussed. Lastly, we discuss the limitations of CNMs applied in photocatalysis or even wider fields. We hope this review will project a fast developmental path with providing a wide view of recent preparation methods, applications, prospects and challenges.

Microorganism biotransformation of sulfamethazine (SMT) in aqueous environments is a major concern, especially considering their exposure to coexisting SMT and heavy metals. Phanerochaete chrysosporium (P. chrysosporium) is a more concerned Cadmium (Cd) and SMT hyper accumulation specie. This study, referring to metabolic mechanisms and application, was performed to investigate the single and combined effects of Cd-SMT, including toxicity, resistance, as well as the accumulation and biotransformation by P. chrysosporium. The results revealed that Cd-SMT co-contamination caused increasing active oxygen accumulation, and the number of antioxidant enzyme and non-enzymatic antioxidants were higher than that under the stress of their individual pollution. It was found that P. chrysosporium accumulated high levels of Cd with the increment of 6.98–23.96% induced by Cd-SMT co-contamination compared to under the stress of Cd individual pollution. What's more, the addition of Cd reduced the toxicity of SMT to P. chrysosporium. The decrease of malonaldehyde and the increase of protein also proved that P. chrysosporium held enormous potential to fit in the co-contaminated environment, and to remediate the co-contaminated water especially in the long-term treatment. These results undoubtedly contribute to the development of fungi-based technologies and the applications of P. chrysosporium in realistic environment rather than laboratory simulation environment.

We report a phosphine-catalyzed trans hydroboration of alkynoate esters and amides. The reaction proceeds under mild conditions with exclusive ( E)-selectivity to afford ( E)-β-boryl acrylates and ( E)-β-boryl acrylamides in good to excellent yields. The reaction is tolerant of a variety of functional groups and allows efficient access to novel oxaboroles as well as a pargyline derivative (MAO inhibitor). Theoretical calculations suggest an internal hydride generates a phosphonium allenoxyborane followed by the formation of a key phosphonocyclobutene intermediate that collapses in a stereoselective, rate-limiting step.

Some rivers in China have been seriously contaminated due to the discharge of lead (Pb) smelting wastewater. In this study, biochar-supported nano-chlorapatite (BC-nClAP) was synthesized to immobilize Pb in contaminated sediment. The remediation effect of BC-nClAP on Pb-contaminated sediment was evaluated through batch experiments and the materials were characterized by x-ray diffraction, scanning electron microscope, Brunner-Emmet-Teller and electronic differential system. It was found that BC-nClAP can transform Pb effectively from labile fraction into stable fraction with a maximum transformation efficiency increasing to 94.1% after 30 days of treatment, and the stabilization efficiency of toxicity characteristic leaching procedure reached 100% only after 16 days of treatment. The content of available phosphorus (AP) in the sediments treated by BC-nClAP was much less than that treated by nClAP, which indicated a lower risk of eutrophication and suggested the dissolution-precipitation mechanism involved in Pb immobilization. BC-nClAP presented the best immobilization efficiency of Pb and the content of organic matters in BC-nClAP treated samples increased the most, thus the OM might play an important role during the Pb immobilization.

A remarkable bioinspired EDDA-mediated method for the selective construction of biologically interesting and highly strained bridged methanodibenzo[b,f][1,5]dioxocin flavonoid scaffold was uncovered by starting from a variety of readily available acylphloroglucinol and 2-hydroxycinnamaldehyde substrates. This method merges a fascinating olefin isomerization/hemiacetallization/dehydration/[3 + 3]-type cycloaddition cascade reaction driven by an in situ generated chromenylium intermediate and provides a convenient and viable synthetic strategy for the efficient access of such flavonoid analogues.

CoWO 4 microrings assembled by nanorods were synthesized by a simple solvothermal method. The morphology and structure of the as-prepared unique CoWO 4 microrings were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and high-resolution TEM (HRTEM). The as-prepared CoWO 4 sample with abundant active sites demonstrated good catalytic activity for glucose electrooxidation in alkaline solution. CoWO 4 modified glass carbon electrode (CoWO 4 -GCE) exhibited good electro-catalytic performance towards glucose detection, it offered a wider linear range, a low detection limit of 0.27 μM, high selectivity, and long-term operational stability. The results showed the as-prepared CoWO 4 microrings can be utilized to construct an enzyme-free glucose sensor based on GCE.

Endocrine-disrupting compounds (EDCs) can interfere with endocrine systems and bio-accumulate through the food chain and even decrease biodiversity in contaminated areas. This review discusses a critical overview of recent research progress in the biotransformation of EDCs (including polychlorinated biphenyl and nonylphenol, and suspected EDCs such as heavy metals and sulfonamide antibiotics) by white rot fungi (WRF) based on techniques with an emphasis on summarizing and analyzing fungal molecular, metabolic and genetic mechanisms. Not only intracellular metabolism which seems to perform essential roles in the ability of WRF to transform EDCs, but also advanced applications are deeply discussed. This review mainly reveals the removal pathway of heavy metal and antibiotic pollutants because the single pollution almost did not exist in a real environment while the combined pollution has become more serious and close to people's life. The trends in WRF technology and its related advanced applications which use the combined technology, including biocatalysis of WRF and adsorption of nanomaterials, to degrade EDCs have also been introduced. Furthermore, challenges and future research needs EDCs biotransformation by WRF are also discussed. This research, referring to metabolic mechanisms and the combined technology of WRF with nanomaterials, undoubtedly contributes to the applications of biotechnology. This review will be of great benefit to an understanding of the trends in biotechnology for the removal of EDCs.

Biomass power generation projects involve green and renewable energy. This study regards Laifa Straw Recycling Company of Henan Sheqi as an example. Field survey and economic analysis are employed as the main research methods. The problems of straw collection, storage, and transportation are examined. According to the data obtained from the investigation and the mathematical model, when the straw recycling company uses the artificial model, the average price of each ton of straw is 385.4 yuan; when the straw recycling company uses the mechanical model, the average price of each ton of straw is 264.4 yuan. Comparison of the mechanical and artificial models reveals that the average price of each ton of straw differs by 121 yuan. Under the assumption that the annual purchase amount of straw is 2 × 10 5 tons, the cost of 2.42 × 10 7 yuan per year can be saved. Thus, Laifa Straw Recycling Company of Henan Sheqi should consider the mechanical model. Sensitivity analysis of the two models shows that the collection cost is the most sensitive factor when the straw recycling company utilizes the artificial model because most farmers go out to work, so a shortage in rural labor force occurs; this shortage results in increased cost of artificial collection. When the straw recycling company utilizes the mechanical model, the cost of storage is the most sensitive factor because of the large storage amount. High current land leasing and management costs lead to increased storage cost.

Astronomers have discovered thousands of planets outside the solar system, most of which orbit stars that will eventually evolve into red giants and then into white dwarfs. During the red giant phase, any close-orbiting planets will be engulfed by the star, but more distant planets can survive this phase and remain in orbit around the white dwarf. Some white dwarfs show evidence for rocky material floating in their atmospheres, in warm debris disks, or orbiting very closely, which has been interpreted as the debris of rocky planets that were scattered inward and tidally disrupted. Recently, the discovery of a gaseous debris disk with a composition similar to ice giant planets demonstrated that massive planets might also find their way into tight orbits around white dwarfs, but it is unclear whether the planets can survive the journey. So far, the detection of intact planets in close orbits around white dwarfs has remained elusive. Here, we report the discovery of a giant planet candidate transiting the white dwarf WD 1856+534 (TIC 267574918) every 1.4 days. The planet candidate is roughly the same size as Jupiter and is no more than 14 times as massive (with 95% confidence). Other cases of white dwarfs with close brown dwarf or stellar companions are explained as the consequence of common-envelope evolution, wherein the original orbit is enveloped during the red-giant phase and shrinks due to friction. In this case, though, the low mass and relatively long orbital period of the planet candidate make common-envelope evolution less likely. Instead, the WD 1856+534 system seems to demonstrate that giant planets can be scattered into tight orbits without being tidally disrupted, and motivates searches for smaller transiting planets around white dwarfs., Comment: 50 pages, 12 figures, 2 tables. Published in Nature on Sept. 17, 2020. The final authenticated version is available online at: https://www.nature.com/articles/s41586-020-2713-y

The reactions of organic azides with diaryl(dihalo)diboranes(4) were explored, resulting in the observation of a number of surprising reactivity patterns. The reaction of phenyl azide with 1,2-diaryl-1,2-dihalodiboranes(4) resulted in the formation of five-membered rings comprising diboryl-triazenes with retention of the boron-boron bond, while the reaction of the peculiar 1,1-di(9-anthryl)-2,2-difluorodiborane(4) with phenyl azide yielded a six-membered ring bearing a diboryl-triazene, whereby the B-B bond was ruptured by the insertion of an arylnitrene-like reactive intermediate. Both types of heterocycles feature unprecedented connectivity patterns and are very rare examples of boryl triazenes beyond the more common 1,2,3-triazolatoboranes. They are also the product of a unique type of aryl migration from a boron center to the phenyl azide γ-nitrogen center. Lastly, the substitution of 1,2-diaryl-1,2-dihalodiboranes(4) with azide groups, using trimethylsilyl azide as the transfer reagent, yielded boryl-tetrazaboroles and diboryldiazadiboretidines (as side-products), invoking the intermediacy of the first N-boryl-substituted iminoboranes, which are BN isosteres of monoborylated alkynes. The synthetic results are complemented with mechanistic proposals derived from quantum-chemical calculations.

Using a single test to comprehensively evaluate multiple cardiac biomarkers for early diagnosis and prevention of acute myocardial infarction (AMI) has faced enormous challenges. Here, we have developed paper-based fluorogenic immunodevices for multiplexed detection of three cardiac biomarkers, namely, human heart-type fatty acid binding protein (FABP), cardiac troponin I (cTnI), and myoglobin, simultaneously. The detection is based on a strategy using zinc oxide nanowires (ZnO NWs) to enhance fluorescence signals (∼5-fold compared to that on pure paper). The immunodevices showed high sensitivity and selectivity for FABP, cTnI, and myoglobin with detection limits of 1.36 ng/mL, 1.00 ng/mL, and 2.38 ng/mL, respectively. Additionally, the paper-based immunoassay was rapid (∼5 min to complete the test) and portable (using a homemade chamber with a smartphone and an ultraviolet lamp). The developed devices integrated with ZnO NWs enable quantitative, sensitive, and simultaneous detection of multiple cardiac biomarkers in point-of-care settings, which provides a useful approach for monitoring AMI diseases and may be extended to other medical diagnostics and environmental assessments.

In this paper, we report a simple, feasible and low-cost method to fabricate self-standing metallic materials using cellulose-based biomass as sacrificial templates. This process involves the impregnation of metallic precursors to the cellulose fibers of biomass templates and the transformation of the precursors to corresponding metals or metal oxides (as well as the removal of the cellulose framework) at an elevated temperature. The structures of the metallic materials as fabricated take the form of architectures of biomass templates (e.g., chromatography paper, medical absorbent cotton, catkins of reed, seed balls of oriental plane, and petals of peach blossom), and the various kinds of metals and metal oxides fabricated with these templates include silver, gold, anatase, cupric oxide, zinc oxide, etc. We have demonstrated photocatalytic and bactericidal applications of such metallic materials, and they should find more applications in electronics, catalysis, energy storage, biomedicine and so on.

Cytorhizins A–D, four novel polyketide heterodimers, were isolated from the endophytic fungus Cytospora rhizophorae A761. These new compounds shared an unprecedented 6/6/5/6/8 or 6/6/5/6/7 pentacyclic ring system and fused as a fascinating cagelike skeleton, embodying by a polyoxygenated isopentyl unit and a highly structure-combined benzophenone scaffold. Their structures were elucidated by extensive spectroscopic analyses and X-ray diffraction techniques. Moreover, compounds 1–4 were evaluated for in vitro cytotoxicity and antimicrobial activity.

Five new compounds including two stilbenes, designated thujasutchins A (1) and B (2), two phenolic compounds namely thujasutchins C (3) and D (4), as well as one sesquiterpene thujasutchin E (5), were isolated from the 95% ethanolic extract from the trunks and roots of Thuja sutchuenensis. Their structures were determined by means of extensively spectroscopic analysis including UV, IR, HRESIMS, 1H and 13C NMR (COSY, HSQC, HMBC). Moreover, compounds 1, 3-5 were evaluated for in vitro cytotoxic activities against SF-268, MCF-7, HepG-2, and A549 tumor cell lines.

Low-mass M dwarfs represent the most common outcome of star formation, but their complex emergent spectra hinder detailed studies of their composition and initial formation. The measurement of isotopic ratios is a key tool that has been used to unlock the formation of our Solar System, the Sun, and the nuclear processes within more massive stars. We observed GJ 745AB, two M dwarfs orbiting in a wide binary, with the IRTF/iSHELL spectrograph. Our spectroscopy of CO in these stars at the 4.7 micron fundamental and 2.3 micron first-overtone rovibrational bandheads reveals 12C16O, 13C16O, and 12C18O in their photospheres. Since the stars are fully convective, the atomic constituents of these isotopologues should be uniformly mixed throughout the stars' interiors. We find that in these M dwarfs, both 12C/13C and 16O/18O greatly exceed the Solar values. These measurements cannot be explained solely by models of Galactic chemical evolution, but require that the stars formed from an ISM significantly enriched by material ejected from an exploding core-collape supernova. These isotopic measurements complement the elemental abundances provided by large-scale spectroscopic surveys, and open a new window onto studies of Galactic evolution, stellar populations, and individual systems., 11 pages, 4 data files, 3 figures, 2 tables. ApJ in press

Most known terrestrial planets orbit small stars with radii less than 60% that of the Sun. Theoretical models predict that these planets are more vulnerable to atmospheric loss than their counterparts orbiting Sun-like stars. To determine whether a thick atmosphere has survived on a small planet, one approach is to search for signatures of atmospheric heat redistribution in its thermal phase curve. Previous phase curve observations of the super-Earth 55 Cancri e (1.9 Earth radii) showed that its peak brightness is offset from the substellar point $-$ possibly indicative of atmospheric circulation. Here we report a phase curve measurement for the smaller, cooler planet LHS 3844b, a 1.3 Earth radius world in an 11-hour orbit around a small, nearby star. The observed phase variation is symmetric and has a large amplitude, implying a dayside brightness temperature of $1040\pm40$ kelvin and a nightside temperature consistent with zero kelvin (at one standard deviation). Thick atmospheres with surface pressures above 10 bar are ruled out by the data (at three standard deviations), and less-massive atmospheres are unstable to erosion by stellar wind. The data are well fitted by a bare rock model with a low Bond albedo (lower than 0.2 at two standard deviations). These results support theoretical predictions that hot terrestrial planets orbiting small stars may not retain substantial atmospheres., Comment: Published in Nature on Aug 19, 2019. Co-authors Koll, Morley and Hu contributed equally to this manuscript

Recent years have seen increasing interest in the characterization of sub-Neptune sized planets because of their prevalence in the Galaxy, contrasted with their absence in our solar system. HD 97658 is one of the brightest stars hosting a planet of this kind, and we present the transmission spectrum of this planet by combining four HST transits, twelve Spitzer/IRAC transits, and eight MOST transits of this system. Our transmission spectrum has higher signal to noise ratio than that from previous works, and the result suggests that the slight increase in transit depth from wavelength 1.1 to 1.7 microns reported in previous works on the transmission spectrum of this planet is likely systematic. Nonetheless, our atmospheric modeling results are not conclusive as no model provides an excellent match to our data. Nonetheless we find that atmospheres with high C/O ratios (C/O >~ 0.8) and metallicities of >~ 100x solar metallicity are favored. We combine the mid-transit times from all the new Spitzer and MOST observations and obtain an updated orbital period of P=9.489295 +/- 0.000005 d, with a best-fit transit time center at T_0 = 2456361.80690 +/- 0.00038 (BJD). No transit timing variations are found in this system. We also present new measurements of the stellar rotation period (34 +/- 2 d) and stellar activity cycle (9.6 yr) of the host star HD 97658. Finally, we calculate and rank the Transmission Spectroscopy Metric of all confirmed planets cooler than 1000 K and with sizes between 1 and 4 R_Earth. We find that at least a third of small planets cooler than 1000 K can be well characterized using JWST, and of those, HD 97658b is ranked fifth, meaning it remains a high-priority target for atmospheric characterization., Accepted to AJ. 29 pages, 21 figures, 11 tables, 2 machine-readable tables (system RVs and TSM values). v2: updated typos

A novel three-dimensional (3D) vertical-flow paper-based device (3VPD), integrated with a sandwich-type fluorescent immunoassay, was developed for multiplexed detection of cancer biomarkers simultaneously based on the principle of origami. The developed 3VPD, composed of a sample layer, a splitting layer, and a test layer, could be fabricated simply by wax-printing on paper at a large scale. Herein, a vertical-flow immunoassay was introduced into the device, in which fluorescein isothiocyanate labeled antibodies were coated on the splitting layer and mouse monoclonal capture antibodies were functionalized on the test layer. The proposed 3VPD showed high sensitivity and selectivity for detecting three cancer biomarkers, carcinoembryonic antigen (CEA), a-fetoprotein (AFP), and cancer antigen 199 (CA199) with detection limits of 0.03 ng/mL, 0.05 ng/mL, and 0.09 U/mL in human serum, respectively. The results obtained in human serum were compatible with the reference values which were acquired from parallel single-analyte. The developed 3VPD provides a new strategy to develop an inexpensive and sensitive approach for simultaneous detection of multiple analytes and comprehensive clinical diagnosis by a single test.

Three new prenylated stilbenes, named as cajanusins A-C (1-3), and one new natural product cajanusin D (4), along with six known derivatives (5-10) were isolated from the leaves of Cajanus cajan. Their structures were fully elucidated by means of extensive spectroscopic methods and comparison with data in the reported literatures. The new compounds of 1 and 2 were evaluated for in vitro cytotoxic activities against a panel of human cancer cell lines.

In this study, the bamboo biomass loaded with ethylenediaminetetraacetic acid (EDTA) intercalated Mg/Al-layered double hydroxides (LDH) was calcined to obtain a novel nano-adsorbent (BC@EDTA-LDH), and BC@EDTA-LDH was used to remove hexavalent chromium (Cr(VI)) in aqueous solutions. The results showed that the interaction between LDH and Cr(VI) on biochar played a dominant part in adsorption. The LDH of Cr(VI) intercalation was successfully reconstructed after adsorption. Fourier transform infrared spectra and X-ray diffraction results confirmed the reconstruction of Mg/Al-LDH. LDH had sustained release effect on the solution. As the pH values increased, the electrostatic repulsion between Cr2O72− and OH– increased, and there existed competition for adsorption sites. The maximum adsorption capacity of Cr(VI) was 38 mg/g. The data was well-fitted with pseudo second-order model and Langmuir-Freundlich model. BC@EDTA-LDH showed a high adsorption capacity and was potentially suitable for removing heavy metals in wastewater.

Cellular network configuration plays a critical role in network performance. In current practice, network configuration depends heavily on field experience of engineers and often remains static for a long period of time. This practice is far from optimal. To address this limitation, online-learning-based approaches have great potentials to automate and optimize network configuration. Learning-based approaches face the challenges of learning a highly complex function for each base station and balancing the fundamental exploration-exploitation tradeoff while minimizing the exploration cost. Fortunately, in cellular networks, base stations (BSs) often have similarities even though they are not identical. To leverage such similarities, we propose kernel-based multi-BS contextual bandit algorithm based on multi-task learning. In the algorithm, we leverage the similarity among different BSs defined by conditional kernel embedding. We present theoretical analysis of the proposed algorithm in terms of regret and multi-task-learning efficiency. We evaluate the effectiveness of our algorithm based on a simulator built by real traces.

Transiting planets in nearby young clusters offer the opportunity to study the atmospheres and dynamics of planets during their formative years. To this end, we focused on K2-25b -- a close-in ($P$=3.48 days), Neptune-sized exoplanet orbiting a M4.5 dwarf in the 650Myr Hyades cluster. We combined photometric observations of K2-25 covering a total of 44 transits and spanning >2 yr, drawn from a mix of space-based telescopes (Spitzer Space Telescope and K2) and ground-based facilities (Las Cumbres Observatory Global Telescope network and MEarth). The transit photometry spanned 0.6--4.5$��$m, which enabled our study of K2-25b's transmission spectrum. We combined and fit each dataset at a common wavelength within a Markov Chain Monte Carlo framework, yielding consistent planet parameters. The resulting transit depths ruled out a solar-composition atmosphere for K2-25b for the range of expected planetary masses and equilibrium temperature at a $>4��$ confidence level, and are consistent with a flat transmission spectrum. Mass constraints and transit observations at a finer grid of wavelengths (e.g., from the Hubble Space Telescope) are needed to make more definitive statements about the presence of clouds or an atmosphere of high mean molecular weight. Our precise measurements of K2-25b's transit duration also enabled new constraints on the eccentricity of K2-25's orbit. We find K2-25b's orbit to be eccentric ($e>0.20$) for all reasonable stellar densities and independent of the observation wavelength or instrument. The high eccentricity is suggestive of a complex dynamical history and motivates future searches for additional planets or stellar companions., v2 updated for proofs

The occurrence rate of hot Jupiters from the Kepler transit survey is roughly half that of radial velocity surveys targeting solar neighborhood stars. One hypothesis to explain this difference is that the two surveys target stars with different stellar metallicity distributions. To test this hypothesis, we measure the metallicity distribution of the Kepler targets using the Hectochelle multi-fiber, high-resolution spectrograph. Limiting our spectroscopic analysis to 610 dwarf stars in our sample with log(g)>3.5, we measure a metallicity distribution characterized by a mean of [M/H]_{mean} = -0.045 +/- 0.00, in agreement with previous studies of the Kepler field target stars. In comparison, the metallicity distribution of the California Planet Search radial velocity sample has a mean of [M/H]_{CPS, mean} = -0.005 +/- 0.006, and the samples come from different parent populations according to a Kolmogorov-Smirnov test. We refit the exponential relation between the fraction of stars hosting a close-in giant planet and the host star metallicity using a sample of dwarf stars from the California Planet Search with updated metallicities. The best-fit relation tells us that the difference in metallicity between the two samples is insufficient to explain the discrepant Hot Jupiter occurrence rates; the metallicity difference would need to be $\simeq$0.2-0.3 dex for perfect agreement. We also show that (sub)giant contamination in the Kepler sample cannot reconcile the two occurrence calculations. We conclude that other factors, such as binary contamination and imperfect stellar properties, must also be at play., 19 pages, 17 figures, submitted to ApJ

A problem of much current practical interest is the replacement of the wiring infrastructure connecting approximately 200 sensor and actuator nodes in automobiles by an access point. This is motivated by the considerable savings in automobile weight, simplification of manufacturability, and future upgradability. A key issue is how to schedule the nodes on the shared access point so as to provide regular packet delivery. In this and other similar applications, the mean of the inter-delivery times of packets, i.e., throughput, is not sufficient to guarantee service-regularity. The time-averaged variance of the inter-delivery times of packets is also an important metric. So motivated, we consider a wireless network where an Access Point schedules real-time generated packets to nodes over a fading wireless channel. We are interested in designing simple policies which achieve optimal mean-variance tradeoff in interdelivery times of packets by minimizing the sum of time-averaged means and variances over all clients. Our goal is to explore the full range of the Pareto frontier of all weighted linear combinations of mean and variance so that one can fully exploit the design possibilities. We transform this problem into a Markov decision process and show that the problem of choosing which node's packet to transmit in each slot can be formulated as a bandit problem. We establish that this problem is indexable and explicitly derive the Whittle indices. The resulting Index policy is optimal in certain cases. We also provide upper and lower bounds on the cost for any policy. Extensive simulations show that Index policies perform better than previously proposed policies.