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Acenapththylene-imide (AnI), similar to naphthalene diimide (NDI), is an outstanding building block for organic functional materials and has gained a lot of research attention. Herein, Sulphur and Selenium-embedded AnI-containing polycyclic aromatic hydrocarbon molecules, AnI-SQ and AnI-SeQ, with [1,2,5]thiadiazolo[3,4-g]quinoxaline (SQ) and [1,2,5]selenadiazolo[3,4-g]quinoxaline (SeQ) are designed and synthesized with low-lying LUMO energy levels. The absorption and emission of AnI-SQ and AnI-SeQ displayed a bathochromic shift upon protonation of the C = N bond. Besides, theoretical calculation indicates remarkable rigid planar backbones for both AnI-SQ and AnI-SeQ. Through self-assembly with polymeric Pluronic® F-127, corresponding hydrophilic nanoparticles (NPs) were prepared with low cytotoxicity. And AnI-SQ NPs could be applied for in vitro two-photon fluorescence imaging.

Herein, we present a mild and efficient method for synthesizing enantioenriched tetrahydroquinoline-fused cyclobutenes through a cascade reaction between 1,2-dihydroquinolines and alkynones with catalysis by chiral spiro-bicyclic bisboranes. The bisboranes served two functions: first they catalyzed a hydride transfer to convert the 1,2-dihydroquinoline substrate to a 1,4-dihydroquinoline, and then they activated the alkynone substrate for an enantioselective [2+2] cycloaddition reaction with the 1,4-dihydroquinoline generated in situ.

Plesiomonas shigelloides, a member of the family Vibrionaceae, is a gram-negative, rod-shaped, facultative anaerobic bacterium with flagella. P. shigelloides has been isolated from such sources as freshwater, surface water, and many wild and domestic animals. P. shigelloides contains 102 Oantigens and 51 H-antigens. The diversity of O-antigen gene clusters is relatively poorly understood. In addition to O1 and O17 reported by other laboratories, and the 12 O serogroups (O2, O10, O12, O23, O25, O26, O32, O33, O34, O66, O75, and O76) reported previously by us, in the present study, nine new P. shigelloides serogroups (O8, O17, O18, O37, O38, O39, O44, O45, and O61) were sequenced and annotated. The genes for the O-antigens of these nine groups are clustered together in the chromosome between rep and aqpZ. Only O38 possesses the wzm and wzt genes for the synthesis and translocation of O-antigens via the ATP-binding cassette (ABC) transporter pathway; the other eight use the Wzx/Wzy pathway. Phylogenetic analysis using wzx and wzy showed that both genes are diversified. Among the nine new P. shigelloides serogroups, eight use wzx/wzy genes as targets. In addition, we developed an O-antigen-specific PCR assay to detect these nine distinct serogroups with no cross reactions among them.

In this paper, the east ore section of the Pulang porphyry copper deposit is selected as the research object. The micro-thermometer and laser Raman spectroscopic technique are utilized to study the parameters of ore-forming fluids such as pressure, temperature, and compositions. In the meantime, the fractal models, including the perimeter-area (P-A) model and number-size (N-S) model, are introduced to quantify the shape of fluid inclusions, and distinguish the stages of ore-forming fluids, respectively. The results show that the types of fluid inclusions are diversified, namely two-phase liquid-rich type, two-phase vapor-rich type, three-phase CO2-rich type, three-phase halite-bearing type and pure liquid type. The fluids of main mineralization stage are characterized by medium-high temperature (170.2–421.4 °C), medium-high salinity (9.3 wt.%–33.3 wt.%), and low density (0.73–1.06 g/cm3). With the migration and evolution, the temperature, salinity, and pressure of ore-forming fluids gradually decrease, while the density of fluids increases. The liquid-phase compositions mainly include H2O, and the vapor-phase compositions consist of H2O, CH4, N2, and CO2, indicating the characteristics of reducing fluids and the mixing of atmospheric precipitation. In general, the characteristics of ore-forming fluids in the east ore section are similar to those of the first mining area, suggesting that the ore-forming fluids in the east ore section may not migrate from the first mining area. And the east ore section may be a relatively independent metallogenic system. Moreover, the fractal analysis results demonstrate that the shape of fluid inclusions formed in the same hydrothermal activity features self-similarity. The DAP values of fluid inclusions in B veins, ED veins, and D veins are 1.04, 1.06 and 1.10, respectively, showing a gradually increasing trend from the main stage to the late stage of mineralization. Meanwhile, the shape of fluid inclusions ranging from B veins to D veins becomes increasingly irregular. It also reveals that the homogenization temperature satisfies fractal distribution with four scale-invariant intervals, suggesting that all B veins, ED veins, and D veins have experienced at least four hydrothermal activities. Compared with histogram, the N-S fractal model is able to describe the distribution characteristics of the ore-forming fluids’ homogenization temperature more precisely. Therefore, it presents a potential tool for the stage division of ore-forming fluids. This research provides information about the characteristics of ore-forming fluids in the east ore section of the Pulang porphyry copper deposit, which is beneficial for further exploration in this region, and the extension of the application of fractal models in the study of fluid inclusions. However, further testing of fractal models on the fluid inclusion study is warranted to fully determine the universality.

This work focused on the rain-induced characteristics of synthetic aperture radar (SAR) at the C- and X-bands. Six SAR images were collected in tropical cyclones: four C-band dual-polarized Sentine...

Correlated cell migration in fibrous extracellular matrix (ECM) is important in many biological processes. During migration, cells can remodel the ECM, leading to the formation of mesoscale structures such as fiber bundles. However, how such mesoscale structures regulate correlated single-cells migration remains to be elucidated. Here, using a quasi-3D in vitro model, we investigate how collagen fiber bundles are dynamically re-organized and guide cell migration. By combining laser ablation technique with 3D tracking and active-particle simulations, we definitively show that only the re-organized fiber bundles that carry significant tensile forces can guide strongly correlated cell migration, providing for the first time a direct experimental evidence supporting that matrix-transmitted long-range forces can regulate cell migration and self-organization. This force regulation mechanism can provide new insights for studies on cellular dynamics, fabrication or selection of biomedical materials in tissue repairing, and many other biomedical applications.

The occurrence of economic policies and other sudden and large shocks often bring out jumps in financial data, which can be characterized through continuous-time jump-diffusion model. In this paper...

Wearable and implantable pressure sensors are in great demand for personalized health monitoring. Pressure sensors with low operation voltage and low power-consumption are desired for energy-saving devices. Organic iontronic devices, such as organic electrochemical transistors (OECTs), have demonstrated great potential for low power-consumption bioelectronic sensing applications. The ability to conduct both electrons and ions, in addition to their low-operation voltage has enabled the widespread use of OECTs in different biosensing fields. However, despite these merits, OECTs have not been demonstrated for pressure sensing applications. This is because most OECTs are gated with aqueous electrolyte, which fails to respond to external pressure. Here, a low power-consumption iontronic pressure sensor is presented based on an OECT, in which an ionic hydrogel is used as a solid gating medium. The resultant iontronic device operated at voltages less than 1 V, with a power-consumption between ~ 101– $10^{3} \mu \text{W}$ , while maintaining a tunable sensitivity between 1 ~ 10 kPa−1. This work places OECTs on the frontline for developing low power-consumption iontronic pressure sensors and for biosensing applications.

For non-fullerene acceptors (NFAs) with linear A2-A1-D-A1-A2 backbone, there are three kinds of possible intermolecular interaction, A1-A1, A1-A2 and A2-A2 stacking. Hence, it is a huge challenge to control this interaction and investigate the effect of intermolecular stacking model on the photovoltaic performance. Here, we adopt a feasible strategy, by utilizing different substituent groups on terminal A2 unit of dicyanomethylene rhodanine (RCN), to modulate this stacking model. According to theoretical calculation results, the molecule BTA3 with ethyl substituent packs via heterogeneous interaction between A2 and A1 unit in neighboring molecules. Surprisingly, the benzyl group can effectively transform the aggregation of BTA5 into homogeneous packing of A2-A2 model, which might be driven by the strong interaction between benzyl and A1 (benzotriazole) unit. However, different with benzyl, phenyl end group impedes the intermolecular interaction of BTA4 due to the large steric hindrance. When using a BTA-based D-π-A polymer J52-F as donor according to “Same-A-Strategy”, BTA3-5 could achieve ultrahigh open-circuit voltage ( V OC) of 1.17–1.21 V. Finally, BTA5 with benzyl groups realized an improved power conversion efficiency (PCE) of 11.27%, obviously higher than that of BTA3 (PCE=9.04%) and BTA4 (PCE=5.61%). It is also worth noting that the same trend can be found when using other four classic p-type polymers of P3HT, PTB7, PTB7-Th and PBDB-T. This work not only investigates the intermolecular interaction of A2-A1-D-A1-A2 type NFAs for the first time, but also provides a straightforward and universal method to change the interaction model and improve the photovoltaic performance.

Herein, we report that highly chemoselective and enantioselective reduction of 2-vinyl-substituted pyridines has been achieved for the first time. The reaction, which uses chiral spiro-bicyclic bisboranes as catalysts and HBpin and an acidic amide as reducing reagents, proceeds through a cascade process involving 1,4-hydroboration followed by transfer hydrogenation of a dihydropyridine intermediate. The retained double bond in the reduction products permits their conversion to natural products and other useful heterocyclic compounds by simple transformations.

For the selection of fund managers in fund investment, traditional measurement methods were mainly based on descriptive analysis and regression modeling for a small sample of numerical data. They did not make full use of the relevant big data information of fund managers and ignored the nonlinearity between data. As a result, the prediction error was large. In this paper, we use the heterogeneous data of fund managers, such as numerical data and textual data, to fully explore the characteristic factors of fund performance, and further employ the artificial intelligence algorithms including the traditional machine learning models and deep learning model to consider the nonlinear characteristics between the data to identify the style of fund managers. It is found that there is a nonlinear characteristic between the characteristic factor and the performance of the fund. The artificial intelligence algorithm, especially, the deep learning method has a better performance in the classification and prediction of fund managers, especially, after adding text information. The research in this paper has enriched the application of intelligent investment advisor in fund investment to a certain extent, and provided a scientific basis for investors’ choice.

J- and H-aggregates of π-conjugated dyes are particularly interesting because of their unique optical and excitonic properties. However, the control of sizes and morphology of J- and H-aggregates r...

ortho-Selective carbene C-H insertion of unprotected phenols is achieved with dimethyl diazomalonate under the catalysis of [Rh(COD)Cl]2. After the C-H insertion, subsequent cyclization and electrophilic addition of another carbene molecule affords tris-carboxylate-substituted 2-benzofuranones as the final reaction products. The enantioselective variant has been developed with the use of chiral diene ligands. Mechanistic experiments indicate that a transient oxonium ylide directing group might be responsible for the regiocontrol at the C-H activation step.

Herein, we report a method for in situ generation of N-aryliminium ions via reactions of N,N-dimethylanilines with diiodomethane. We used the method to prepare tetrahydroquinolines via one-pot three-component reactions between N,N-dimethylanilines, diiodomethane, and olefins. This transformation involves initial reaction of the aniline with diiodomethane to form an iodomethylammonium salt, which undergoes fragmentation accompanied by elimination of methyl iodide to give an N-aryliminium ion, which is trapped by the olefin via [4 + 2] cycloaddition to give the final product. This method for generating N-aryliminium ions requires neither a catalyst nor a strong oxidant, suggesting that it can be expected to find broad utility, especially for substrates that are sensitive to Lewis acids, transition metals, or strong oxidants.

With the development of large-area fabrication technologies for organic solar cells (OSCs), poly(3-hexylthiophene) (P3HT) is the best choice as a photovoltaic donor polymer because it can be easily synthesized in the scale of kilograms at low cost. However, non-fullerene acceptors (NFAs) matching with P3HT for high performance OSCs are very rare. Herein, by introducing oxygen atoms into the side chains or the fused-ring core of indaceno[1,2

During rainfall, asphalt pavement structure layers are often not saturated. To study the dynamic response of unsaturated permeable asphalt pavement under moving load, 3-D finite element models for asphalt pavements with coupling of water–air–force were built based on unsaturated seepage theory. The vertical stress, the transverse stress, and the pore-water pressure, the vertical displacement responses of the asphalt pavement under moving loads were investigated. In addition, the results were compared and analyzed with that of the saturated permeable asphalt pavement. The results showed that the maximum transverse stress of the unsaturated asphalt pavement was about 200 kPa, while the saturated asphalt pavement was about 300 kPa. It is showed that the discharge of water has a great effect on avoiding cracks in the pavement. The maximum pore-water pressure of the unsaturated asphalt pavement is 56.67 kPa, and that of the saturated asphalt pavement decreases by 40.70 % in the same condition. The change of displacement in the area near the upper layer is more remarkable, and the maximum displacement of the saturated asphalt pavement is less than that of the unsaturated asphalt pavement. The vertical stress, transverse stress and pore-water pressure of the unsaturated asphalt pavement are smaller than saturated asphalt pavement. The asphalt pavement is prone to structural damage such as fatigue cracking and pit slot by dynamic water scouring when it is saturated condition. Therefore, the drainage inside the pavement is very important for the service life of the asphalt pavement. It ensures the asphalt pavement is unsaturated during rainfall. In future road construction, more permeable pavements should be considered. Keywords: Unsaturated seepage, Water–air–force coupling, Vertical stress, Transverse stress, Pore-water pressure

Odd-numbered primary alcohols are components of plant cuticular wax, but their biosynthesis remains unknown. We isolated a rice wax crystal-sparse leaf 5 (WSL5) gene using a map-based cloning strategy. The function of WSL5 was illustrated by overexpression and knockout in rice, heterologous expression in Arabidopsis and transient expression in tobacco leaves. WSL5 is predicted to encode a cytochrome P450 family member CYP96B5. The wsl5 mutant lacked crystalloid platelets on the surface of cuticle membrane, and its cuticle membrane was thicker than that of the wild-type. The wsl5 mutant is more tolerant to drought stress. The load of C23 -C33 alkanes increased, whereas the C29 primary alcohol reduced significantly in wsl5 mutant and WSL5 knockout transgenic plants. Overexpression of WSL5 increased the C29 primary alcohol and decreased alkanes in rice leaves. Heterologous expression of WSL5 increased the C29 primary alcohol and decreased alkanes, secondary alcohol, and ketone in Arabidopsis stem wax. Transient expression of WSL5 in tobacco leaves also increased the production C29 primary alcohol. WSL5 catalyzes the terminal hydroxylation of alkanes, yielding odd-numbered primary alcohols, and is involved in the formation of epidermal wax crystals on rice leaf, affecting drought sensitivity.

The main objective of this paper is to propose a newly developed ocean Significant Wave Height (SWH) retrieval method from Envisat Advanced Synthetic Aperture Radar (ASAR) imagery. A series of wave mode imagery from January, April and May of 2011 are collocated with ERA-Interim reanalysis SWH data. Based on the matched datasets, a simplified empirical relationship between 22 types of SAR imagery parameters and SWH products is developed with the Genetic Algorithms Partial Least-Squares (GA-PLS) model. Two major features of the backscattering coefficient S10 and the frequency parameter S10 are chosen as the optimal training feature subset of SWH retrieval by using cross validation. In addition, we also present a comparison of the retrieval results of the simplified empirical relationship with the collocated ERA-Interim data. The results show that the assessment index of the correlation coefficient, the bias, the root-mean-square error of cross validation (RMSECV) and the scattering index (SI) are 0.78, 0.07 m, 0.76 m and 0.5, respectively. In addition, the comparison of the retrieved SWH data between our simplifying model and the Jason-2 radar altimeter data is proposed in our study. Moreover, we also make a comparison of the retrieval of SWH data between our developed model and the wellknown CWAVE_ENV model. The results show that satisfying retrieval results are acquired in the low-moderate sea state, but major bias appears in the high sea state, especially for SWH>5 m.

A novel As(III) sensor was developed by co-electrodepositing a Fe-Chitosan composite to a screen-printed carbon electrode sensor. The newly developed Fe-Chitosan-coated carbon electrode sensor exhibited successful As(III) detection in mining wastewater and soil leachate using square wave anodic stripping voltammetry (SWASV). A noticeable peak was observed at +0.15 V associated with stripping current of As(III) for both real wastewater samples. The calibration curves showed strong correlations with respect to As(III) with the limit of detection (LOD) of 1.12 ppb for mining wastewater and 1.01 ppb for soil leachate, respectively. Lower relative standard deviations (RSD) were obtained with 2.91% for mining wastewater and 4.54% for soil leachate during repeated measurements (n = 8), respectively, indicating enhanced stability for As(III) detection in the real wastewater application. The interference from copper and other metal ions (e.g., Zn(II), Pb(II) and Cd(II)) was found negligible for As(III) detection using the polymer modified Fe-coated electrode sensor, which suggests that the Fe-chitosan composite imparted the selectivity in the presence of other metal ions to As(III) detection in complex water matrix. These results demonstrate the applicability of a novel Fe-Chitosan-coated carbon electrode sensor to real wastewater As(III) pollution monitoring with the acceptable range of characteristics.

Thermogalvanic cells (TGCs) directly convert waste heat to electricity, but the efficiency has been limited largely by the contradiction between thermal resistance and electrical conductance. Here ...

The objective of this paper is to study the spatial and temporal variation characteristics of the UNESCO aridity index (AI) at annual and seasonal temporal scales in northwestern China during the 55-year study period (1961–2015). Based on climate data from 178 meteorological stations provided by the China Meteorological Data Service Center, AI trends were investigated by the Mann-Kendall test. The results showed that the annual and seasonal AIs displayed a mixed pattern of positive and negative trends for the period of 1961–2015 across the study area. In most regions, both annual and seasonal AIs exhibited slightly positive trends in northwestern China. Significant (P

Three quinoxaline-based “D−π–A” conjugated polymers, named as PE61, PE62, and PE63, are utilized to investigate the effect of introducing fluorine and sulfur atoms into the thiophene side chains on...

Canopy conductance (Gc) largely regulates carbon/water cycling and land–atmosphere interactions, but quantifying Gc using eddy flux data is limited by the difficulty of partitioning plant transpiration (T) and surface evaporation (E). We introduced an underlying water use efficiency (uWUE) method to partition evapotranspiration (ET) in an oasis maize ecosystem, and cross–compared with the Shuttleworth and Wallace (SW) model, the lysimeter and isotope measurements. We then estimated surface conductance (Gs) by ET and Gc by T partitioned using the uWUE method, followed by a performance evaluation on the Jarvis model parameterized with both Gs and Gc. The results showed that T/ET estimated by the uWUE method was close to the isotope method in the peak growing season of 2012, it showed similar seasonal variations with the lysimeter/eddy covariance method and the SW model throughout this growing season. Daily T partitioned by the uWUE method was in good agreement with the SW model from 2012 to 2015 (r2 = 0.91). Additionally, Gc had more significant seasonal variations than Gs. The Jarvis model parameterized with Gc exhibited superior performance than those with Gs. Our study suggests that the uWUE method can exclude influences of nonstomatal conductances, and will have great potential to provide more reasonable parameterization for simulation of plant stomata.

A catalytic carbonylative ring-opening and functionalization reaction of poorly activated cyclopropanes has been developed. The key achievement of this work is the accomplishment of an unprecedented effective intermolecular trapping of the rhodacyclopentanone intermediate, which is derived from rhodium-mediated carbonylative insertion of poorly activated cyclopropanes, by an external reactant. The success of this development hinges upon the use of a dual directing strategy.

This paper presents the compact polarized (CP) pseudo quad-pol parameters for the detection of marine oil spills and segregation of lookalikes using simulated CP SAR data from full-polarized (FP) SAR imagery. According to the CP theory, 11 polarized parameters generally used for the detection of oil spills were derived from reconstructed pseudo quad-pol data for both C and L bands. In addition, the reconstruction performance between C and L bands was also compared by evaluating the reconstruction accuracy of retrieved polarized parameters. The results show that apart from σHV and RH, other polarized parameters of σHH, σVV, H, α, φH–V, r, ρH–V, and γ can be reconstructed with satisfactory accuracy for both C and L bands. Furthermore, C band has a higher reconstruction accuracy than L band, especially for φH–V. Moreover, the effect of reconstruction of polarized parameters on oil spill classification was also evaluated using the maximum likelihood classification (MLC) method. According to the evaluation of kappa coefficients and mapping accuracy, it is recommended to use σHH, σVV, H, ρH–V, and γ of the C band CP SAR for marine oil spill classification.

Excellent fouling resistance to various foulants is crucial to maintain the separation performance of membranes in providing potable water. Antimicrobial modification is effective for antibiofouling but fails to mitigate organic fouling. Improving surface charges can improve the resistance to charged foulants, but the lack of antimicrobial ability results in bacterial aggregation. Herein, a silver nanoparticle modified carbon nanotube (Ag-CNT)/ceramic membrane was prepared with enhanced antifouling and antimicrobial properties under electrochemical assistance. The presence of silver nanoparticles endows the composite membrane with antimicrobial ability by which biofilm formation is inhibited. Its steady-state flux is 1.9 times higher than that for an unmodified membrane in filtering bacterial suspension. Although the formation of organic fouling did weaken the biofouling resistance, the negatively charged bacteria and organic matter can be sufficiently repelled away from the cathodic membrane under electrochemical assistance. The flux loss under a low-voltage of 2.0 V decreased to 35% for the membrane alone when bacteria and organic matter coexisted in the feedwater. More importantly, silver dissolution was significantly inhibited via an in situ electroreduction process by which the Ag+ concentration in the effluent (

A new series of spiro-bicyclic bisborane catalysts has been prepared by means of hydroboration reactions of C2 -symmetric spiro-bicyclic dienes with HB(C6 F5 )2 and HB(p-C6 F4 H)2 . When used for hydrogenation of quinolines, these catalysts give excellent yields and enantiomeric excesses, and show turnover numbers of up to 460. The most attractive feature of these metal-free hydrogenation reactions was the broad functional-group tolerance, making this method complementary to existing methods for quinoline hydrogenation.

A novel modified nanoporous bismuth electrode (modified-NPBiE) sensor was prepared by consecutive procedures which consist of bismuth (Bi) and tin (Sn) electroplating, thermal treatment for alloying Bi-Sn film, and selective chemical dealloying of Sn. The newly prepared modified-NPBiE sensor exhibited improved lifetime (2.7 times longer than a conventional nanoporous Bi-filmed electrode with over 40 repeated measurements) sensor with lower relative standard deviation (RSD), indicating enhanced stability and reproducibility for heavy metal detection. Using square wave anodic stripping voltammetry (SWASV), two noticeable peaks were observed at −0.65 V and −0.45 V associated with stripping currents of Cd2+ and Pb2+ in 0.1 M acetate buffer solution at pH 4.6, respectively. The calibration curves showed strong correlations with respect to various concentrations of Cd2+ and Pb2+ with the limit of detection (LOD) of 1.3 ppb for Cd2+ and 1.5 ppb for Pb2+. The newly modified-NPBiE sensor was then successfully applied for detecting Cd2+ and Pb2+ in a tap water environment and exhibited an acceptable performance for measuring heavy metals with a good reliability.

To investigate side chain effect of ETVT based photovoltaic polymers, we designed and synthesized the polymers with different solubilizing substituents. The impact of side chains on the solubility, planarity, optical and electronic properties of these ETVT based conjugated polymers was systematically studied. Extending the intrinsic alkyl group or adding new alkyl substituent to the polymer obviously increased the solubility of the resulting polymers. Thus, the polymerization reaction yield was improved to 88% and 81%, for PETVT-TBT24 and PETVT8-TBT, compared to that of 39% for PETVT-TBT. PETVT8-TBT showed blue-shifted absorption spectrum, reduced hole mobility and consequently inferior photovoltaic performance, owing to the steric hindrance caused by redundant octyl group on ETVT unit. However, the introduction of alkyl substitutes in ETVT remarkably increases the open-circuit voltage of PETVT8-TBT based PSCs to 1.03 V, by both decreasing HOMO of the polymer and reducing the energy losses. Extending the intrinsic alkyl group resolved the problem of low solubility of PETVT-TBT, and furthermore, was benefit to improve charge carrier mobility in the resulting polymer based solar cells. As a result, PETVT-TBT24 basically maintained the advantages of ETVT based photovoltaic polymers, realizing a moderate PCE of 7.8% when paired with the non-fullerene acceptor of ITIC.

Herein, we report that, by using chiral bicyclic bisborane catalysts, we have achieved the first highly regio-, diastereo-, and enantioselective direct asymmetric vinylogous Mannich reactions of acyclic α,β-unsaturated ketones. The strong Lewis acidity and steric bulk of the bisborane catalysts were essential for the observed high yields and selectivities.

We designed a turn-off near-infrared fluorescent fluoride chemosensor NIR-BODIPY-Si through the density functional theory/time-dependent functional theory calculations. In the designed sensor, the tert-butyldimethylsilyloxy moiety responses to the fluoride-triggered desilylation process, and the BODIPY dye serves as fluorophore. The molecular design firstly showed that the possibility of photoinduced electron transfer is low/high in NIR-BODIPY-Si/NIR-BODIPY-O (the desilylation product), thus referring that the fluorescence sensing mechanism is a photoinduced electron transfer mechanism that quenched the sensor's fluorescence after detection of fluoride anions. Absorption and emission spectra further demonstrated that the designed sensor is a near-infrared chemosensor. The largest binding energy between NIR-BODIPY-Si and F- suggests that the sensor has an excellent selectivity to F- and the low barrier of the desilylation reaction accounts for the sensor's rapid response speed to F-. We also provided the synthetic routine for the molecule sensor, with the expectation that this molecular design can shed some light on the experimentally based design procedure.

Collective cell migration is crucial to many physiological and pathological processes such as embryo development, wound healing, and cancer invasion. Recent experimental studies have indicated that the active traction forces generated by migrating cells in a fibrous extracellular matrix (ECM) can mechanically remodel the ECM, giving rise to bundlelike mesostructures bridging individual cells. Such fiber bundles also enable long-range propagation of cellular forces, leading to correlated migration dynamics regulated by the mechanical communication among the cells. Motivated by these experimental discoveries, we develop an active-particle model with polarized effective attractions (APPA) to investigate emergent multicellular migration dynamics resulting from ECM-mediated mechanical communications. In particular, the APPA model generalizes the classic active-Brownian-particle (ABP) model by imposing a pairwise polarized attractive force between the particles, which depends on the instantaneous dynamic states of the particles and mimics the effective mutual pulling between the cells via the fiber bundle bridge. The APPA system exhibits enhanced aggregation behaviors compared to the classic ABP system, and the contrast is more apparent at lower particle densities and higher rotational diffusivities. Importantly, in contrast to the classic ABP system where the particle velocities are not correlated for all particle densities, the high-density phase of the APPA system exhibits strong dynamic correlations, which are characterized by the slowly decaying velocity correlation functions with a correlation length comparable to the linear size of the high-density phase domain (i.e., the cluster of particles). The strongly correlated multicellular dynamics predicted by the APPA model is subsequently verified in in vitro experiments using MCF-10A cells. Our studies indicate the importance of incorporating ECM-mediated mechanical coupling among the migrating cells for appropriately modeling emergent multicellular dynamics in complex microenvironments.

International audience; Microchannels created in poly-2-hydroxyethyl methacrylate (poly(HEMA)) hydrogels have the potential to prevent dry-eye disease by facilitating tear exchange. Biosensors are further demonstrated for wearable biosensing applications.Microchannels in hydrogels play an essential role in enabling a smart contact lens. However, microchannels have rarely been created in commercial hydrogel contact lenses due to their sensitivity to conventional microfabrication techniques. Here, we report the fabrication of microchannels in poly(2-hydroxyethyl methacrylate) (poly(HEMA)) hydrogels that are used in commercial contact lenses with a three-dimensional (3D) printed mold. We investigated the corresponding capillary flow behaviors in these microchannels. We observed different capillary flow regimes in these microchannels, depending on their hydration level. In particular, we found that a peristaltic pressure could reinstate flow in a dehydrated channel, indicating that the motion of eye-blinking may help tears flow in a microchannel-containing contact lens. Colorimetric pH and electrochemical Na+ sensing capabilities were demonstrated in these microchannels. This work paves the way for the development of microengineered poly(HEMA) hydrogels for various biomedical applications such as eye-care and wearable biosensing.

The focus of this comparative study was to evaluate the oxidation behavior and related properties of exhaust particulates from dual fuel combustion with various low reactivity fuels. Samples from premixed gasoline, n-butanol and gasoline/n-butanol blends with a fixed substitution of 40% (noted as G40, B40 and G20B20, respectively) were characterized by high-resolution transmission electron microscope (HR-TEM), Raman spectroscopy (RS) and X-ray photoelectron spectroscopy (XPS) and thermogravimetric (TG). TG results showed that the oxidation reactivity of particulates from dual fuel combustion followed the order of G40 > G20B20 > B40, and above particles were more reactive to oxidation than diesel soot. It can be inferred that applying gasoline/diesel dual fuel combustion has beneficial implications for the diesel particulate filter regeneration and even lifetime, in comparison to n-butanol/diesel dual fuel combustion. In comparison to G40 soot, B40 soot exhibited a more ordered nanostructure with longer fringe length but shorter tortuosity from HR-TEM as well as lower ID1/IG and ID3/IG values from RS. Note that the differences in the soot nanostructure between B40 and G20B20 samples were low, and actually the effects of premixed fuels on both soot reactivity and nanostructure were slight. Hence, soot reactivity is only partially structure-controlled. In addition, TEM images showed that soot from premixed butanol had smaller primary particle than premixed gasoline. Particulates from dual fuel combustion exhibited higher C–OH concentrations than diesel soot, but no significant trend can be observed for C O concentrations among various samples. Both primary particle size and oxygenated surface functional groups were not correlated with soot oxidation reactivity.

A mild general method for difluoromethylthiolation of aldehydes with PhSO2SCF2H and a decatungstate photocatalyst under redox-neutral conditions has been developed. This reaction is highly efficient, scalable, and oxidant-free. The broad substrate scope and excellent functional group tolerance of the reaction make it suitable for generating libraries of difluoromethyl thioesters. We demonstrated the utility and sustainability of the method by synthesizing several structurally complex difluoromethyl thioesters.

Due to intensive marine activities and the use of low-quality fuel oils, the marine transport accounts for a considerable part of air pollution in the transportation sector. Although ships provide the convenient transportation, they exhaust a large number of hazardous pollutants, especially nitrogen oxides (NOx) and sulfur oxides (SOx), which have a significant side effect on environment and human health. To alleviate the impact of global shipping on the environment, international maritime organization established the more stringent emission regulations from Tier I to Tier III in order to reduce emissions from ships. As a result, various emission reduction technologies need to be developed in order to meet more stringent regulations in the future and reduce the pollutant emissions. Under this background, it is indispensable to examine the existing emission reduction technologies when exploring another possible method to reduce the pollutant emissions. Based on a significant number of related literatures, it is general to utilize the marine alternative fuels to reduce the pollutant emissions. Especially, liquid natural gas (LNG) is considered to be one of the most promising marine alternative fuels due to its economy and environmentally friendly features. This review thus aims to summarize the different emission reduction technologies of marine diesel engines through three reduction paths of fuel optimization, pre-combustion control and exhaust after-treatment. Furthermore, the utilization of LNG in the marine diesel engines are evaluated comprehensively from three aspects of environmental protection, energy structure and economic benefits. At the end, some suggestions on the future research are given based on the extensive review on the state-of-the-art literature.

The objective of this paper is to analyze land use change on Daishan Island using a multi-temporal remote sensing imagery. Four Landsat optical remote sensing images were collected from 1987, 1996, 2007, and 2016, and eight land cover types were recognized and extracted using the collected time series imagery. In addition, a land use-type transfer matrix was used for temporal analysis of land use conditions. The experimental results reveal that the total area of Daishan Island increased slightly in the past 30 years, during which time the shipbuilding industry rapidly grew and the salt mining industry gradually shrank. The industry changed greatly but there was no large-scale land reclamation. Moreover, forested area increased, which was conducive to the sustainable development of Daishan Island.

Herein, we report a protocol for visible-light-mediated allylation reactions between unactivated alkyl iodides and allyl sulfones under mild conditions with catalysis by inexpensive and readily available Mn2(CO)10. This protocol is compatible with a wide array of sensitive functional groups and has a broad substrate scope with regard to both alkyl iodides and allyl sulfones.

Bulk heterojunction organic solar cells based on perylenediimide (PDI) derivatives as electron acceptors have afforded high power conversion efficiency (PCE) but still lagged behind fullerene-based analogues. Design of novel molecular structures by adjusting the PDI ring and/or connection mode remains the breakthrough point to improve the photovoltaic performance. After introducing benzofuran at the inside bay positions and being linked with a single bond and a fluorene unit, mandatory planar PDI dimers were achieved and named FDI2 and F-FDI2. Both acceptors show high-lying LUMO energy levels and realize high VOC beyond 1.0 V when using the classic polymer of PBDB-T as an electron donor. However, FDI2 and F-FDI2 gave totally different photovoltaic performance with PCEs of 0.15 and 6.33%, respectively. The central fluorene linkage increased the miscibility of materials and ensured a much higher short-circuit current because of the formation of suitable phase separation. Our results demonstrated that utilizing the mandatory planar skeleton of PDI dimers is a simple and effective strategy to achieve high-performance nonfullerene electron acceptors, and the modulation of central conjugated units is also vital.

Herein, we report a mild protocol for direct visible-light-initiated Giese addition of unactivated alkyl iodides to electron-poor olefins (Michael acceptors) with catalysis by decacarbonyl dimanganese, Mn2(CO)10, an inexpensive earth-abundant-metal catalyst. This protocol is compatible with a wide array of sensitive functional groups and has a broad substrate scope with regard to both the alkyl iodide and the Michael acceptor.

Herein, we report a protocol for direct visible-light-mediated Minisci C–H alkylation of heteroarenes with unactivated alkyl halides using molecular oxygen as an oxidant at room temperature. This mild protocol is compatible with a wide array of sensitive functional groups and has a broad substrate scope. Notably, functionalization of (iso)quinolines, pyridines, phenanthrolines, quinazoline, and other heterocyclic compounds with unactivated primary, secondary, and tertiary alkyl halides proceeds smoothly under the standard conditions. The robustness of this protocol is further demonstrated by the late-stage functionalization of complex nitrogen-containing natural products and drugs.

As the most successful end-capped unit in conventional A–D–A type non-fullerene acceptors (NFAs), 1,1-dicyanomethylene-3-indanone (IC) plays a significant role in enhancing the power conversion efficiencies (PCEs) of organic solar cells (OSCs). Here, an A2–A1–D–A1–A2 type NFA of TP28, containing the bridge unit of thieno[3,4-b]pyrazine (TP) and the terminal unit of IC, is designed and synthesized. This is the first time that IC groups are introduced into the A2–A1–D–A1–A2 type NFAs. By selecting four kinds of common electron-withdrawing units including benzothiadiazole (BT), quinoxaline (Qx), benzo[d][1,2,3]triazole (BTA) and TP, we found that the steric hindrance of the A1 unit may be the key factor in controlling the condensation reaction and only the TP unit could obtain the target molecule. Although the electron-donating capability of the central fluorene unit is relatively weak, TP28 exhibits a quite narrow optical bandgap of 1.47 eV. The PBDB-T:TP28 photovoltaic devices demonstrate a moderate PCE of 5.31%, revealing great potential of such kind of NFA for highly efficient bulk-heterojunction (BHJ) OSCs.

The pandemic of coronavirus disease 2019(COVID-19) has threatened the social and economic structure all around the world. Generally, COVID-19 has three possible transmission routes, including pre-symptomatic, symptomatic, and asymptomatic transmission, among which the last one has brought a severe challenge for the containment of the disease. One core scientific question is to understand the influence of asymptomatic individuals and of the strength of control measures on the evolution of the disease, particularly on a second outbreak of the disease. To explore these issues, we proposed a novel compartmental model that takes the infection of asymptomatic individuals into account. We get the relationship between asymptomatic individuals and critical strength of control measures theoretically. Furthermore, we verify the reliability of our model and the accuracy of the theoretical analysis by using the real confirmed cases of COVID-19 contamination. Our results, showing the importance of the asymptomatic population on the control measures, would provide useful theoretical reference to the policymakers and fuel future studies of COVID-19.

Background Few epidemiological investigations have focused on the influence of environmental temperature on human sperm quality. Here, we evaluated the potential association between ambient temperature and human sperm quality in Wuhan, China, and examined the interactive effect of particulate matter (PM2.5) and temperature. Methods 1780 males who had been living in Wuhan for no less than three months and received semen analysis at the Department of Reproductive Medicine in Renmin Hospital of Wuhan University between April 8, 2013 and June 30, 2015 were recruited. Daily mean meteorological data and air pollution data (PM2.5, O3 and NO2) in Wuhan between 2013 and 2015 were collected. A generalized linear model was used to explore the associations between ambient temperature and sperm quality (including sperm concentration, percentage of normal sperm morphology, and progressive motility) at 0–9, 10–14, 15–69, 70–90, and 0–90 days before semen examination, and the interaction between temperature and PM2.5. Results The associations between ambient temperature and sperm quality were an inverted U-shape at five exposure windows, except for a lag of 0–9 days for sperm concentration. A 1 °C increase in ambient temperature above the thresholds was associated with a 2.038 (1.292 ~ 2.783), 1.814 (1.217 ~ 2.411), 1.458 (1.138 ~ 1.777), 0.934(0.617 ~ 1.251) and 1.604 (1.258 ~ 1.951) decrease in the percentage of normal sperm morphology at lag 0–9, lag 10–14, lag 15–69, lag 70–90, and lag 0–90 days, respectively. The interaction p-values of PM2.5 and temperature were mostly less than 0.05 at five exposure windows. When ambient temperature exposure levels were above the thresholds, a 0.979 (0.659–1.299) and 3.559 (0.251 ~ 6.867) decrease in percentage of normal sperm morphology per 1 °C increase in temperature at lag 0–90 days was observed in the PM2.5 ≤ P50 group and PM2.5 > P50 group, respectively. Conclusions Our results indicate that exposure to ambient temperature has a threshold effect on sperm quality, and PM2.5 enhances the effect of temperature on sperm quality when temperatures are above the threshold.

Catalytic amounts of B(C6F5)3 have been found to be able to promote the intramolecular cyclization of vinyl-substituted N,N-dialkyl arylamines to afford nitrogen-containing heterocycles. Our mechanistic studies indicate the reaction is initiated by abstraction of an α-hydride from an N-alkyl substituent by B(C6F5)3, which is followed by cyclization, and is concluded by delivery of the hydride to the cyclic cationic intermediate. The dual roles of B(C6F5)3, first as an oxidant and then as a hydride-carrying reductant, have enabled a rare redox-neutral cyclization process between a sp3 carbon and an electron-rich olefin without using a transition metal or an external oxidant.

Linear A–D–A or A−π–D−π–A architectures are predominant in the design of promising nonfullerene acceptors (NFAs), which promoted the rapid progress of organic solar cells. However, utilization of four electron-accepting units (A) to construct four-armed NFAs is rarely reported and the relationship of structure–properties–performance is unclear. In this study, we designed and synthesized a novel acceptor (A401) with an (AA)−π–D−π–(AA) configuration, where four 1,1-dicyanomethylene-3-indanone groups were used as the end-capped segments. When A401 was paired with a classic p-type polymer PBDB-T, a power conversion efficiency of 7.54% could be achieved, which was much higher than that of the reported two-armed analogue of DC-IDT-2T (3.93%). The improved photovoltaic performance of A401 should be ascribed to the high electron affinity. Our results indicate introducing more end-capped electron-accepting units is a simple and effective alternative strategy for the design of promising NFAs. Our conceptualized mol...

We prepared a new class of chiral C2 -symmetric bicyclic bisborane catalysts by addition reactions of internal dienes with the Piers borane, HB(C6 F5 )2 , and an analogue, HB(p-C6 F4 H)2 . The dependence of the addition pattern on the reaction temperature allowed us to selectively prepare two diastereomeric catalysts from a single diene precursor. The bisboranes prepared in situ exhibited excellent activity (turnover numbers up to 200 at -40 °C) and enantioselectivity (up to 95 % ee) in imine hydrogenation reactions.

Conductive polymer (CP) nanotubes are fascinating nanostructures with high electrical conductivity, fast charge/discharge capability, and high mechanical strength. Despite these attractive physical properties, progress in the synthesis of CP nanotube hydrogels is still limited. Here, we report a facile and effective approach for the synthesis of polypyrrole (PPy) nanotube hydrogels by using the weakly interconnected network of self-assembled nanotubes of lithocholic acid as a soft template. The PPy nanotube hydrogels are then converted to aerogels by freeze drying, in which PPy nanotubes form elastic and conductive networks with a density of 38 mg/cm3 and an electrical conductivity of 1.13 S/m. The PPy nanotube aerogels are able to sustain a compressive strain as high as 70% and show an excellent cyclic compressibility due to their robust nanotube networks and hierarchically porous structures, which allow the compressive stress to be easily dissipated. Furthermore, PPy nanotube aerogels show negative stra...

2-(1,1-Dicyanomethylene)rhodanine (RCN) is an important electron-deficient terminal unit to build non-fullerene acceptors (NFAs) having been realized high power conversion efficiency (PCE) beyond 12% with complicated p-type polymer as electron donor. However, the photovoltaic properties of RCN-based NFAs are unsatisfied when paired with the classic p-type polymer poly(3-hexylthiophene) (P3HT). In order to make a contribution in this regard, we designed two RCN-based small molecular acceptors with A2–A1–D–A1–A2 structure, BT3 and BTA3, where benzothiadiazole (BT) and benzotriazole (BTA) are bridged A1 segments, respectively, to modulate the optoelectronic properties. As a result, P3HT:BTA3 solar cell exhibits a promising PCE of 5.64%, with a VOC of 0.90 V and a fill factor (FF) of 0.65, which is obviously much better than that of P3HT:BT3 (PCE = 2.55%, VOC = 0.72 V, FF = 0.61). The higher electron mobility of P3HT:BTA3 film indicates BTA3 tends to form a continuous pathway for electron transport even at a ...

A self-nanocrystallization layer was prepared on the surface of a Ti alloy sample via shot peening to investigate its influence on the follow-up diffusion bonding between a titanium alloy and a TiAl-based alloy. The experiment results show that surface self-nanocrystallization treatment can accelerate the interface reaction between a Ti alloy and a TiAl alloy, lowering the bonding temperature of the sound joints by more than 50 K. Moreover, the thickness of the interface reaction layer plays an important role in the interfacial bonding strength. In this work, the maximum shear strength of the joint appears to have a thickness of about 1.8 μm. As a consequence, it is found that surface self-nanocrystallization treatment is helpful for optimizing the diffusion bonding process.