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Heat transfer and mixing of highly viscous fluid in shell-and-tube heat exchangers are challenging. Computational fluid dynamics was applied to investigate the hydrodynamics, mixing, heat transfer and residence time distribution characteristics for highly viscous fluid in a shell-and-tube heat exchanger with X-type baffle (HEX), which is a novel baffle configuration proposed in this work. The influence of structural parameters, including the length-diameter ratio, the combination pattern of baffles and the crossbar number, was discussed. The results indicate that a smaller length-diameter ratio results in better dispersive and distribution mixing performance, and higher heat transfer coefficient, but leads to higher pressure drop. The increase of crossbar number will reduce the heat transfer coefficient and pressure drop, while improve the comprehensive performance. The analysis on the impact of structural parameters provides guidance for the design and optimization of HEX. For the evaluation of process intensification effect, HEX was considered for comparison with Sulzer mixer reactor (SMR), which has been proved to be an efficient heat exchanger for highly viscous fluid. The significant radial flow motion and effective splitting and remixing processes of fluid in HEX result in better distribution mixing performance. The heat transfer performance of HEX is equivalent to that of SMR when Re<0.03 and better than SMR when Re>0.03 at the cost of higher pressure drop. In addition, the residence time distribution of HEX is narrower than that of SMR, making it easier for the process control of highly viscous fluid.

Crop production is a large source of atmospheric ammonia (NH3), which poses risks to air quality, human health and ecosystems1–5. However, estimating global NH3emissions from croplands is subject to uncertainties because of data limitations, thereby limiting the accurate identification of mitigation options and efficacy4,5. Here we develop a machine learning model for generating crop-specific and spatially explicit NH3emission factors globally (5-arcmin resolution) based on a compiled dataset of field observations. We show that global NH3emissions from rice, wheat and maize fields in 2018 were 4.3 ± 1.0 Tg N yr−1, lower than previous estimates that did not fully consider fertilizer management practices6–9. Furthermore, spatially optimizing fertilizer management, as guided by the machine learning model, has the potential to reduce the NH3emissions by about 38% (1.6 ± 0.4 Tg N yr−1) without altering total fertilizer nitrogen inputs. Specifically, we estimate potential NH3emissions reductions of 47% (44–56%) for rice, 27% (24–28%) for maize and 26% (20–28%) for wheat cultivation, respectively. Under future climate change scenarios, we estimate that NH3emissions could increase by 4.0 ± 2.7% under SSP1–2.6 and 5.5 ± 5.7% under SSP5–8.5 by 2030–2060. However, targeted fertilizer management has the potential to mitigate these increases.

Correcting atmospheric effects over inland and coastal waters poses a significant challenge in ocean color applications due to the prevalence of strongly absorbing aerosols, often resulting in overcorrection during atmospheric correction (AC) processes. To address this challenge, our previous study introduced novel global gridded aerosol models tailored for inland and coastal regions. However, further comprehensive validation is needed to assess the performance of these new aerosol models in obtaining remote sensing reflectance (Rrs) under different water conditions and across various satellite missions. In this study, we compiled global in situ Rrs data to compare the performance of the new gridded aerosol models with NASA’s standard aerosol models in AC across three satellite missions: MODIS Aqua (MODISA), Visible Infrared Imaging Radiometer Suite (VIIRS), and Landsat 8 Operational Land Imager (OLI). Our findings indicate that the new aerosol model consistently outperforms the standard aerosol model across nearly all spectral bands of the three satellite missions. Importantly, it notably mitigates the overcorrections typically observed with the standard models. These results underscore the effectiveness and applicability of globally gridded aerosol models for AC over inland and coastal waters across different satellite missions.

In this paper, a nonlocal two-component complex modified Korteweg–de Vries (mKdV) equation is investigated and its Darboux transformation is derived. By using the Darboux transformation, soliton solutions are obtained which include dark soliton solution, quasi-W-type soliton, quasi-M-type soliton and periodic solution.

The past decades have witnessed tremendous progress on radical reactions. However, in comparison with carbon, nitrogen, oxygen, and other main group element centered radicals, the synthetic chemistry of boron centered radicals was less studied, mainly due to the high electron-deficiency and instability of such 3-center–5-electron species. In the 1980s, Roberts and co-workers found that the coordination of a Lewis base (amines or phosphines) with the boron center could form 4-center–7-electron boryl radicals (Lewis base–boryl radicals, LBRs) that are found to be more stable. However, only limited synthetic applications were developed. In 2008, Curran and co-workers achieved a breakthrough with the discovery of N-heterocyclic carbene (NHC) boryl radicals, which could enable a range of radical reduction and polymerization reactions. Despite these exciting findings, more powerful and valuable synthetic applications of LBRs would be expected, given that the structures and reactivities of LBRs could be easily modulated, which would provide ample opportunities to discover new reactions. In this Account, a summary of our key contributions in LBR-enabled radical borylation reactions and selective activation of inert carbon–heteroatom bonds will be presented.

Phytoplankton blooms in coastal oceans can be beneficial to coastal fisheries production and ecosystem function, but can also cause major environmental problems1,2—yet detailed characterizations of bloom incidence and distribution are not available worldwide. Here we map daily marine coastal algal blooms between 2003 and 2020 using global satellite observations at 1-km spatial resolution. We found that algal blooms occurred in 126 out of the 153 coastal countries examined. Globally, the spatial extent (+13.2%) and frequency (+59.2%) of blooms increased significantly (P< 0.05) over the study period, whereas blooms weakened in tropical and subtropical areas of the Northern Hemisphere. We documented the relationship between the bloom trends and ocean circulation, and identified the stimulatory effects of recent increases in sea surface temperature. Our compilation of daily mapped coastal phytoplankton blooms provides the basis for global assessments of bloom risks and benefits, and for the formulation or evaluation of management or policy actions.

Here, in situ Raman spectroscopy is used to develop a method for determining in real time the percentage of esterification denoted as Ester%, a key quality index of polymerization processes in polyester industries. Specifically, Raman spectra of the polymerization (esterification and polyesterification) of terephthalic acid (PTA) and 1,4-butanediol (BDO) to obtain poly(butylene terephthalate) (PBT) are monitored as a function of reaction time. They are processed through a background subtraction algorithm to yield Raman spectra, which allows for the identification and quantification of Raman bands corresponding to the ester and carboxylic groups. The Ester% is calculated by the ratio between the ester and carboxylic groups in terms of the characteristic peak intensities or areas. The ratio based on the Raman peak areas yields more satisfactory results, namely, the calculated values of the Ester% are less noisy and agree better with those obtained by titration. The established in situ Raman spectroscopy method allows for real-time monitoring and quantification of the Ester% during the polymerization process. It will be adopted for process optimization and control at a pilot scale and ultimately at an industrial production scale.

The construction of diversely substituted all-carbon quaternary centers has been a longstanding challenge in organic synthesis. Methods that add three alkyl substituents to a simple C(sp3) atom rely heavily on lengthy multiple processes, which usually involve several preactivation steps. Here, we describe a straightforward three-step sequence that uses a range of readily accessible activated trichloromethyl groups as the carbon source, the three C–Cl bonds of which are selectively functionalized to introduce three alkyl chains. In each step, only a single C–Cl bond was cleaved with the choice of an appropriate Lewis base–boryl radical as the promoter. A vast range of diversely substituted all-carbon quaternary centers could be accessed directly from these activated CCl3trichloromethyl groups or by simple derivatizations. The use of different alkene traps in each of the three steps enabled facile collections of a large library of products. The utility of this strategy was demonstrated by the synthesis of variants of two drug molecules, whose structures could be easily modulated by varying the alkene partner in each step. The results of kinetic and computational studies enabled the design of the three-step reaction and provided insights into the reaction mechanisms.

High-quality oxygen isotope analysis of composition-variable minerals (e.g., ubiquitous carbonates) using secondary ion mass spectrometry (SIMS) is extremely challenging. The classical off-line procedure, which requires additional electron probe microanalyzer (EPMA) chemical compositions for calibrating instrumental mass fractionation (IMF), is inherently inaccurate and analytically inefficient. In this study, the first accurate and paired SIMS analysis of δ18O and Fe# [molar Fe/(Mg + Fe)] in dolomite is reported. Based on five newly developed dolomite O-isotopic standards with an Fe# range of 0.01–0.35 obtained by SIMS, a novel accurate and rapid online matrix effect calibration method for dolomite O-isotope analysis was developed using concurrent SIMS 18O–16O–56Fe16O–24Mg16O measurements without additional chemical electron probe microanalysis. A logistic equation was proposed as the best-fit curve to represent the δ18O matrix effect based on the 56Fe16O/24Mg16O ratios. For CTD-4 carbonatitic dolomite with variable Fe# but homogeneous oxygen isotopes, the off-line method exhibited highly variable apparent δ18O values in the range of 5.74–10.11‰. The online method yielded a homogeneous δ18O value of 7.94 ± 0.34‰ (2SD, n= 40), which is comparable with that of bulk analysis (7.94 ± 0.20‰; 2SD). Comprehensive analyses validated the online method as the best strategy for performing accurate δ18O analysis of samples with highly heterogeneous compositions. Based on its accuracy, simplicity, and economic feasibility, this method has potential applications in the analysis of composition-complex dolomites, detrital dolomites, and other precious terrestrial and extraterrestrial materials.

Objective This study aims to investigate potential beneficial actions of icariin (ICA) on testicular spermatogenic function in male rats with streptozotocin (STZ)-induced diabetes and to explore the underlying mechanisms. Background:ICA was found to reduce blood glucose, regulate the endocrine function of the reproductive system, and improve testicular spermatogenic function.Methods Adult rats were intraperitoneally injected with STZ (65 mg/kg) to induce type 1 diabetes mellitus (T1DM). Diabetic rats were randomly classified intoT1DM (n= 6) and T1DM + ICA (n= 6) groups. Rats without STZ and ICA treatment were assigned as control group (n= 6). The morphology of testicular tissues was examined by histological staining. The mRNA and protein expression levels were determined by quantitative real-time PCR, Western blot and immunostaining, respectively.Results Rats from T1DM group showed a reduction in epididymis and testis weight, and a decrease in sperm count when compared to control group (p< 0.01), which was attenuated by ICA treatment (p< 0.05) Diabetic rats from T1DM group also exhibited reduced diameter and area of seminiferous tubules, along with decreased spermatogonia and primary spermatocytes number when compared to control group (p< 0.01), which was partially reversed by ICA treatment (p< 0.05) Rats from T1DM group exhibited down-regulation of PCNA mRNA and protein in the testis when compared to control group (p< 0.01); while ICA treatment up-regulated PCNA expression in the testis of diabetic rats compared to T1DM group (p< 0.05). Rats from T1DM group showed up-regulation of Bax and capase-3 and down-regulation of Bcl-2, PKM2, HK2 and lactate dehydrogenase A in the testes when compared to control group (p< 0.05), which was reversed by ICA treatment (p< 0.05).Conclusion These findings suggest that ICA may exert its protective effects on testicular damage in diabetic rats through modulation of glycolysis pathway and suppression of apoptosis.

Nutrients such as phosphorus and nitrogen lead to extensive growth of harmful algae in lakes and reservoirs, which results in eutrophication. The driving mechanism of primary productivity change in lakes and reservoirs at a wide spatial and temporal scale remains largely unknown. We establish a water quality database using a stacking machine learning model, including monthly chlorophyll‐a (Chl‐a), total nitrogen (TN) and phosphorus (TP) concentrations in 255 lakes and 332 reservoirs from 1980 to 2018. We find an increase in the number of lakes and reservoirs at risk of algal blooms, with approximately 2.66% exhibiting Chl‐a concentrations exceeding 30 μg L−1by 2018. Variations in Chl‐a concentrations were not entirely synchronized at the individual and regional levels with TN and TP concentrations, or their stoichiometric ratios, as estimated by a hierarchical linear model spanning 1980 to 2018. Further, we discovered unexpected effects of geographical features (i.e., latitude, longitude, and slope) and meteorological factors (i.e., air temperature) on Chl‐a concentrations in the lakes and reservoirs with higher TP concentrations (>0.041 mg L−1for lakes and >0.027 mg L−1for reservoirs), through the use of multiple regression trees and structural equation model analysis. Our findings underscore the importance of (a) implementing flexible nutrient pollution control approaches based on nutrient ecoregions that consider geographical variations, and (b) developing mitigation and adaptation strategies to address the uncertain risks posed by climate change in the prevention and control of eutrophication in lakes and reservoirs. We achieved high accuracy in predicting Chl‐a concentrations using a stacking modelTN and TP and their stoichiometric ratios did not always align with Chl‐a concentrationsGeographical characteristics and climatic influences dominate the Chl‐a concentrations with higher TP concentrations We achieved high accuracy in predicting Chl‐a concentrations using a stacking model TN and TP and their stoichiometric ratios did not always align with Chl‐a concentrations Geographical characteristics and climatic influences dominate the Chl‐a concentrations with higher TP concentrations

Algal blooms constitute an emerging threat to global inland water quality, yet their spatial and temporal distribution at the global scale remains largely unknown. Here we establish a global bloom database, using 2.91 million Landsat satellite images from 1982 to 2019 to characterize algal blooms in 248,243 freshwater lakes, representing 57.1% of the global lake area. We show that 21,878 lakes (8.8%) spread across six continents have experienced algal blooms. The median bloom occurrence of affected lakes was 4.6%, but this frequency is increasing; we found increased bloom risks in the 2010s, globally (except for Oceania). The most pronounced increases were found in Asia and Africa, mostly in developing countries that remain reliant on agricultural fertilizer. As algal blooms continue to expand in scale and magnitude, this baseline census will be vital towards future risk assessments and mitigation efforts.

Introduction: Based on the modified couple stress theory and the hyperbolic tangential mixed shear deformation theory, the free vibration and the transient responses of the functionally graded piezoelectric (FGP) sandwich microplates with considering the thermal–electric effects are investigated. Methods: By introducing the porosity volume fraction, the perfect FGP sandwich mocroplate are destroyed and porous FGP sandwich plates are constructed. Electro-elastic material properties of porous FGP microplate vary across the thickness based on the modified power-law model. The governing equations derived from Hamilton's principle are solved analytically. Results: By comparisons with the FEM simulation results and the previous results in the literature, the accuracy of the present established models is confirmed. Then the influences of thermal loadings, porosity volune fraction, material gradation, length scale to thickness ratios and facesheet thickness on the dynamic behaviors of FGP sandwich microplates are discussed. Significance: These research can provide a theoretical basis for the accurate design of smart structures made of functionally graded piezoelectric materials.

The unique geometry of screw extruders allows handling very viscous media; thus, they can be used as continuous reactors to conduct polymerization reactions without using any solvents. This is called reactive extrusion polymerization. It is an intensified process as it maximizes reaction rates upon maximizing the concentrations of monomers and an initiator/catalyst (if there is any). It also allows conducting polymerization reactions at higher temperatures, without having to take measures to prevent solvents from evaporating or to work under pressure. However, screw extruders are not suitable for the early stage of polymerization in which the viscosity of the polymerization system may not be high enough for the rotation of the screws to generate a steady flow. A combination of continuously stirred tank reactors and a twin-screw extruder or several in series is preferred for the polymerization process. This review shows how reactive extrusion may intensify different types of polymerization processes under the constraint of no solvents, such as free-radical polymerization, anionic polymerization, ring-opening polymerization, and polycondensation, on one hand; and how challenges are met, on the other hand.

The epigenetic modification of hepatitis B virus (HBV) covalently closed circular DNA (cccDNA) plays a crucial role in cccDNA transcription and viral persistence. Interferon-α (IFN-α) is a pivotal agent against HBV cccDNA. However, the mechanism by which IFN-α modulates the epigenetic regulation of cccDNA remains poorly understood. In this study, we report that IFN-α2b enhances the histone deacetylase 3 (HDAC3)-mediated de-2-hydroxyisobutyrylation of histone H4 lysine 8 (H4K8) on HBV cccDNA minichromosome to restrict the cccDNA transcription in liver. By screening acetyltransferases and deacetylases, we identified that HDAC3 was an effective restrictor of HBV transcription and replication. Moreover, we found that HDAC3 was able to mediate the de-2-hydroxyisobutyrylation of H4K8 in HBV-expressing hepatoma cells. Then, the 2-hydroxyisobutyrylation of histone H4K8 (H4K8hib) was identified on the HBV cccDNA minichromosome, promoting the HBV transcription and replication. The H4K8hib was regulated by HDAC3 depending on its deacetylase domain in the system. The low level of HDAC3 and high level of H4K8hib were observed in the liver tissues from HBV-infected human liver-chimeric mice. The levels of H4K8hib on HBV cccDNA minichromosome were significantly elevated in the liver biopsy specimens from clinical hepatitis B patients, which was consistent with the high transcriptional activity of cccDNA. Strikingly, IFN-α2b effectively facilitated the histone H4K8 de-2-hydroxyisobutyrylation mediated by HDAC3 on the HBV cccDNA minichromosome in primary human hepatocytes and hepatoma cells, leading to the inhibition of HBV transcription and replication. Our finding provides new insights into the mechanism by which IFN-α modulates the epigenetic regulation of HBV cccDNA minichromosome.

Inspired by chameleons’ structural color regulation capability, a simple, but effective, swelling method is proposed for the first time to prepare an ionic polyacrylamide (PAAm) organogel for simultaneous tactile sensing and interactive color changing. The PAAm organogel obtained by swelling the PAAm scaffold in the dimethyl sulfoxide solution of organic electrochromic material (OECM) shows an extremely large stretchability with an elongation of 1600%, a supersoftness with a compressive modulus of 7.2 kPa, an excellent transmittance up to 90%, and a very fast response time of 0.5 s combined with the characteristic of interactive color changing. The PAAm organogel also suggests a universal design ability to tailor coloration spectra for tactile sensors via simply changing the type and content of OECM. The tactile sensor based on a PAAm organogel is capable of serving as a wearable device for precisely tracing human body motion performance and directly visualizing the stress distribution via interactive color changing capability. It is demonstrated that the swelling method proposed here is a simple and practical strategy to prepare ionic organogels with both piezo-resistive and electrochromic effects.

A copper-catalyzed anti-Markovnikov hydrosilylation of alkynes with PhSiH3was reported. This reaction represents a notable and efficient example on copper-catalyzed hydrosilylatioin of alkynes, which shows excellent recognition between the terminal and internal triple bonds. Various (hetero)aromatic and aliphatic substituted terminal alkynes underwent this reaction to afford the (E)-vinylsilanes in high yields and with excellent regioselectivity.

The hydrodynamics and local turbulent mixing of parallel multiple liquid jets, submerged in liquid, were investigated by means of experiments and computational fluid dynamics (CFD). A renormalization group (RNG) k-ε turbulence model was used to simulate the flow field. The model was validated experimentally by particle image velocimetry (PIV) measurements. In the converging region adjacent to the nozzle exits, the recirculation region disappears, and there is only ambient fluid entrainment. Different jet arrays were compared to evaluate the effects of the jet spatial arrangement on the hydrodynamics and mixing performance. A shorter mixing length in the merging region suggests that mixing is more efficient in the triple-jet system than in other jet systems. Compared with the jet Reynolds number, the jet spacing plays a more significant role in determining the critical mixing regions, while the linear relationship between them is more sensitive than that for multiple parallel plane jets.

Under investigation in this paper are the nonlocal symmetries and consistent Riccati expansion integrability of the (2 + 1)-dimensional Boussinesq equation, which can be used to describe the propagation of long waves in shallow water. By constructing the Bäcklund transformation, we obtain the truncated Painlevé expansion of the system. Its Schwarzian form is also derived, whose nonlocal symmetry is localized to provide the corresponding nonlocal group. Furthermore, we verify that the system is solvable via the consistent Riccati expansion (CRE). Based on the CRE, the interaction solutions between soliton and cnoidal periodic wave are explicitly studied.

Over the years, a number of state-of-the-art data analysis tools have been developed to provide a comprehensive analysis of data collected from gas chromatography–mass spectrometry (GC–MS). Unfortunately, the time shift problem remains unsolved in these tools. Here, we developed a novel comprehensive data analysis strategy for GC–MS-based untargeted metabolomics (AntDAS-GCMS) to perform total ion chromatogram peak detection, peak resolution, time shift correction, component registration, statistical analysis, and compound identification. Time shift correction was specifically optimized in this work. The information on mass spectra and elution profiles of compounds was used to search for inherent landmarks within analyzed samples to resolve the time shift problem across samples efficiently and accurately. The performance of our AntDAS-GCMS was comprehensively investigated by using four complex GC–MS data sets with various types of time shift problems. Meanwhile, AntDAS-GCMS was compared with advanced GC–MS data analysis tools and classic time shift correction methods. Results indicated that AntDAS-GCMS could achieve the best performance compared to the other methods.

A radical borylative cyclization reaction of 1,6-dienes was developed to assemble boron-handled six-membered heterocycles and carbocycles. This reaction was initiated by the chemo- and regio-controlled addition of an N-heterocyclic carbene–boryl radical to one of the alkene tethers, followed by an intramolecular 6-exocyclization to afford a six-membered ring framework. The utility of this method was demonstrated in the synthesis of diverse paroxetine analogues through late-stage derivatization of the boryl functional unit.

This work takes advantage of the unique thermally reversible dissociation/association feature of C–ON bonds in alkoxyamine (Diol) to facilitate the reprocessability of poly(butyl methanol methacrylate) (PBMM) rubber with excellent thermal and mechanical properties. Isocyanate groups were incorporated into the PBMM backbone and then reacted with hydroxyl groups in Diol to obtain cross-linked PBMM rubber. Although its cross-linking degree is slightly lower than the conventional cross-linked rubber by an irreversible cross-linker (Dieg), it shows a higher tensile strength and elongation at break. Its decomposition temperature is about 50 °C higher than PBMM cross-linked by Dieg. Furthermore, the dissociation of C–ON bond at high temperature can break the cross-linking network of PBMM rubber to form a flowable and reprocessable melt and show an excellent ability of reshaping and healing; the association of thermally reversible C–ON bond can completely recover the cross-linking network and mechanical properties at a low temperature.

Objective: Training load is the key point of sports training. The training and practice present that appropriate load during altitude training plays a positive role in aerobic ability and performance. The purpose of this paper is to explore the characteristics and differences of the training loads of elite rowers during the 8-week altitude training, to explore the impact of different training loads on performance. It expects to provide a theoretical basis and methodological reference to improve rowing's altitude training. Methods : 32 rowers from the national rowing team is divided into two groups with 18 women of single oar and 14 women scullers and train at Huize Yunnan (2 280 m) for 8 weeks. The training load before, during and after the altitude training is recorded. The training volume (km) consist of water training, ergometer training and running; the training intensity consist of 5 levels, which are evaluated by heart rate and blood lactic acid. The specific performance by ergometer 6 km, 2 km and 4 level incremental load test before and after altitude training are tested. BU and CK at the morning after rest day are also tested. Results : (1) From the view of training volume, the average week's volume of women of singe oar is 7.1km less than women scullers at sea level, volume of water training is 11.2km less; the volume of women of single oar decreases from 195km at sea level to 164.1km during altitude training (-15. 85%), whereas the volume of women scullers decreases from 184. 2km to 171. 2km (-7. 06%); (2) from the view of training intensity, the proportion of oxygen utilize 2 of women of single oar is 118. 27% larger than women scullers whereas the proportions of oxygen utilize 1, anaerobic threshold and oxygen transport of women of single oar are less than women sculler, -30. 47% (P<0.01), -20.29% (P>0.05) and -48.65% (P>0.05); (3) after altitude training, ergometer 6km result of women of singe oar decreases by 0. 04% (P>0. 05) whereas women scullers improve by 0. 77%(P<0. 01), and result of women scullers is better than women of singe oar; the change of power and heart rate at lactic acid threshold of women scullers are better than women of single oar; ergometer 2km result of women of single oar decrease by 0. 31 %(P>0. 05) whereas women sculler improve by 0. 73% (P<0. 01); (4) during altitude training, average BU and CK of women of single oar is 6.1±1. 5mmol/l and 162.6±83.6 U/l, women scullers is 6.4±1.4mmol/ and 249. 4±176.7 U/l; there is a significant difference between CK of two groups (P<0.05). Conclusions: Training volume of Chinese rowers during altitude training should remain similar to the sea level; the training should rely mainly on water training, and ergometer training and running are supplementary; the training intensity of the Chinese rowers should rely mainly on oxygen utilize 1 (60-65%), and focus on developing aerobic ability, and anaerobic threshold and oxygen transport training are supplementary; the difference in load structure of Chinese rowers' altitude training is mainly load intensity of oxygen utilization 2 and oxygen utilization 1, and higher proportion of oxygen utilization 1 intensity training may be the main reason for better training effect. [ABSTRACT FROM AUTHOR]

A regioselective radical hydroboration of gem-difluoroalkenes was developed for the synthesis of α-difluoroalkylborons. The reaction features excellent regioselectivity, broad substrate scope, and good functional group capability. DFT calculations implicated the remarkable α-selectivity was driven from the kinetically and thermodynamically more favorable α-addition step. The resulting α-difluoroalkylborons could be readily converted into NHC–borane-tethered monofluoroalkenes, which demonstrated unique reactivity and applicability in the synthesis of monofluoroalkene derivatives through transformations of the boron unit.

A recently developed algorithm to estimate surface ocean chlorophyll aconcentrations (Chl in mg m−3), namely, the ocean color index (OCI) algorithm, has been adopted by the U.S. National Aeronautics and Space Administration to apply to all satellite ocean color sensors to produce global Chl maps. The algorithm is a hybrid between a band‐difference color index algorithm for low‐Chl waters and the traditional band‐ratio algorithms (OCx) for higher‐Chl waters. In this study, the OCI algorithm is revisited for its algorithm coefficients and for its algorithm transition between color index and OCx using a merged data set of high‐performance liquid chromatography and fluorometric Chl. Results suggest that the new OCI algorithm (OCI2) leads to lower Chl estimates than the original OCI (OCI1) for Chl < 0.05 mg m−3, but smoother algorithm transition for Chl between 0.25 and 0.40 mg m−3. Evaluation using in situ data suggests that similar to OCI1, OCI2 has significantly improved image quality and cross‐sensor consistency between SeaWiFS, MODISA, and VIIRS over the OCx algorithms for oligotrophic oceans. Mean cross‐sensor difference in monthly Chl data products over global oligotrophic oceans reduced from ~10% for OCx to 1–2% for OCI2. More importantly, data statistics suggest that the current straylight masking scheme used to generate global Chl maps can be relaxed from 7 × 5 to 3 × 3 pixels without losing data quality in either Chl or spectral remote sensing reflectance (Rrs(λ), sr−1) for not just oligotrophic oceans but also more productive waters. Such a relaxed masking scheme yields an average relative increase of 39% in data quantity for global oceans, thus making it possible to reduce data product uncertainties and fill data gaps. There are generally two issues with any remote sensing data product: data quality (accuracy) and data quantity (coverage). In this work, these two issues for global ocean data products of chlorophyll aconcentrations (Chl in mg m−3) are investigated through revisiting a recently developed algorithm concept and statistical analyses of cloud‐adjacent data. The use of more data in algorithm development leads to slightly different algorithm coefficients and smoother transition between clear and turbid waters, and a new straylight masking scheme is proposed to “recover” some of the previously masked data in the global data products. The new algorithm leads to significantly improved cross‐sensor consistency (SeaWiFS, MODIS, VIIRS) as compared to the traditional band‐ratio algorithms, with mean monthly difference reduced from 10% to 1–2%. The new straylight masking scheme leads to relative increase of 39% in data quantity in the global ocean without losing data quality. These improvements are expected to reduce uncertainties and fill gaps in the global data products. OCI chlorophyll aalgorithm revisited for its algorithm coefficients and transitionNew quality‐control scheme proposed to mask straylightBoth data quality and data quantity improved for global oceans

The synergetic effect of a reactive compatibilizer and organo-montmorillonite (OMMT) on phase morphology and properties of polyamide 6 (PA6)/polydimethylsilicone (PDMS) blend with a high viscosity ratio of dispersed phase and matrix was studied. A small amount of an amine-terminated copolymer of polyether amine (PEA) and PDMS (PDMS-b-PEA) as a reactive compatibilizer can significantly decrease the dispersed phase domain size. However, the dispersed phase domain size has still been above 2 μm even when the PDMS-b-PEA concentration reaches 5 wt %. OMMT as the second additive can further dramatically decrease the dispersed phase domain size due to the barrier effect for effectively preventing the coalescence of the dispersed phase domain. Moreover, the presence of PDMS-b-PEA can promote the uniform dispersion of OMMT. The synergetic effect of PDMS-b-PEA and OMMT can also improve tensile properties and decrease water absorption.

A high crop yield with the minimum possible cost to the environment is generally desirable. However, the complicated relationships among crop production, nitrogen (N) use efficiency and environmental impacts must be clearly assessed. We conducted a series of on-farm N application rate experiments to establish the linkage between crop yield and N2O emissions in the Guanzhong Plain in Northwest China. We also examined crop yield, partial factor productivity of applied N (PFPN) and reactive N (Nr) losses through a survey of 1 529 and 1 497 smallholder farms that grow wheat and maize, respectively, in the region. The optimum N rates were 175 and 214 kg ha–1for winter wheat and summer maize, respectively, thereby achieving the yields of 6 799 and 7 518 kg ha–1, correspondingly, with low N2O emissions based on on-farm N rate experiments. Among the smallholder farms, the average N application rates were 215 and 294 kg ha–1season–1, thus producing 6 490 and 6 220 kg ha–1of wheat and maize, respectively. The corresponding PFPN values for the two crops were 36.8 and 21.2 kg N kg–1, and the total N2O emissions were 1.50 and 3.88 kg ha–1, respectively. High N balance, large Nr losses and elevated N2O emissions could be explained by the overdoses of N application and low grain yields under the current farming practice. The crop yields, N application rates, PFPN and total N2O for wheat and maize were 18 and 24% higher, 42 and 37% less, 75 and 116% higher, and 42 and 47% less, correspondingly, in the high-yield and high-PFPN group than in the average smallholder farms. In conclusion, closing the PFPN gap between the current average and the value for the high-yield and high-PFPN group would increase crop production and reduce Nr losses or the total N2O emissions for the investigated cropping system in Northwest China.