Spatial-temporal differentiation and influencing factors of carbon emission trajectory in Chinese cities - A case study of 247 prefecture-level cities

Cities, where human energy activities and greenhouse gas emissions are concentrated, contribute significantly to alleviating the impacts of global climate change. Utilizing the China Carbon Emissions Accounting Database (CEADs) to provide carbon dioxide emission inventories for urban areas in China at the prefecture level, this study closely examines the historical evolution trajectories of carbon emissions across 247 urban units from 2005 to 2019. The logarithmic cubic function model was employed to simulate these trajectories, evaluating urban emission peaks and classifying the different carbon emission trajectories. Further, the Geographical and Temporal Weighted Regression model was employed to explore spatiotemporal traits and essential variables that impact the variations in carbon emissions among four identified trajectory types. Our results showed that Chinese urban carbon emission trajectories can be classified into four categories: a) peaking emissions, b) fluctuating growth, c) continuous growth, and d) passive decline. Specifically, 43 cities, primarily in North China, proactively attained their emission peak post-2010, driven by the reduction in secondary industry and energy intensity. 90 cities, largely industrial hubs in the southeast coast and inland, reached an emission plateau around 2015, exhibiting fluctuating growth due to dependencies on secondary industries. 101 cities, predominantly located in western and central regions, demonstrated a clear upward trend in carbon emissions, propelled by rapid urbanization and heavy industry-oriented economic development. Lastly, 13 cities, typically in the northeastern and southwestern regions, experienced a passive decline in carbon emissions, attributable to resource depletion or economic downturns. It is evident that China's city-level carbon peaking has demonstrated some effectiveness, yet considerable progress is still required.

Quantifying the influence of size, shape, and density of microplastics on their transport modes: A modeling approach

Microplastics (MPs) pose significant risks to marine ecosystems and human health, necessitating accurate predictions of their distributions in aquatic environments for effective risk mitigation. However, understanding MP transport dynamics is challenging because of the inadequate representation of MP characteristics such as size, shape, and density in numerical models. Further, the accuracy of the MP vertical profiles in existing models has not been thoroughly validated. Thus, we developed an MP transport model within the Finite Volume Community Ocean Model framework (FVCOM-MP) by integrating MP characteristics. We validated FVCOM-MP against experimental and analytical data, focusing on various MP transport modes and transitions. FVCOM-MP successfully replicates MP profiles in different transport modes, including the bedload, surface load, suspended load, and mixed load modes. Additionally, we introduce phase diagrams for classifying MP transport modes based on particle characteristics, enhancing our understanding of MP dynamics in aquatic systems. The transport modes for a number of real-world MP particles, including fishing line, plastic bag/bottle fragments, synthetic fibers, tire wear particles, polyvinyl chloride and expanded polystyrene pellets, were analyzed with these phase diagrams.

A comparative study of satellite altimetry-based and DEM-based methods for estimating lake water volume changes

This study compared two different methods, the satellite altimetry-based and DEM (digital elevation model)-based, for estimating lake water volume changes. We focused on 34 lakes in China as the testing sites to compare the two methods for lake water volume changes from 2005 to 2020. The satellite altimetry-based method used water levels provided by the DAHITI (Database for Hydrological Time Series of Inland Waters) data and surface areas derived from Landsat imagery. The DEM-based method used the SRTM DEM data in combination with Landsat-derived lake extents. Our results showed a high degree of consistency in lake water volume changes estimated between the two methods (R2 > 0.90), but each method has its limitations. In terms of temporal coverage, the satellite altimetry-based method with the DAHITI data is limited by missing water level data in certain periods. The performance of the DEM-based method in extracting lake shore boundaries in regions with flat terrains (slope <1.5°) is not satisfactory. The DEM-based method has complete regional applicability (100%) in the Tibetan Plateau (TP) Lake Region, yet its effectiveness drops significantly in the Xinjiang and Eastern China Plain Lake Regions, with applicability rates of 50 and 40%, respectively.

BF3-Promoted Ring Expansion of Iminylphosphiranes and Acylphosphiranes for Divergent Access to 1,2-Azaphospholidines and 1,2-Dihydrophosphetes

Ring expansion of strained small rings provides an efficient method for the synthesis of various high-value carbocycles and heterocycles. Here we report BF3·Et2O as both an activating reagent and fluorine source, enabling ring expansion of phosphirane and P-F bond formation. Treatment of 1-iminylphosphirane complexes with BF3·Et2O resulted in 1,2-azaphospholidines, while the reaction of 1-acylphosphirane complexes with BF3·Et2O afforded 1,2-dihydrophosphetes. The reaction path was tuned by the nucleophilicity of the N and O atoms toward the intermediate phosphenium cation.

Towards tetrasubstituted furans through rearrangement and cyclodimerization of acetylenic ketones

Cyclodimerization of readily accessible acetylenic ketones facilitated by a phosphane-borane complex under basic conditions is achieved. This methodology allows one-pot synthesis of phosphorus-involved tetrasubstituted furans via the construction of a C-P bond and a furan ring within a single procedure. A plausible reaction mechanism is proposed.

Engineering High-Performance Hypergolic Propellant by Synergistic Contribution of Metal-Organic Framework Shell and Aluminum Core

Hypergolicity is a highly desired characteristic for hybrid rocket engine-based fuels because it eliminates the need for a separate ignition system. Introducing hypergolic additives into conventional fuels through physical mixing is a feasible approach, but achieving highly reliable hypergolic ignition and energy release remains a major challenge. Here, the construction of core-shell Al@metal organic framework (MOF) heterostructures is reported as high-performance solid hypergolic propellants. Upon contact with the liquid oxidizer the uniformly distributed hypergolic MOF (Ag-MOF) shell can induce the ignition of hypergolic-inert fuel Al, resulting in Al combustion. Such a synthetic strategy is demonstrated to be favorable in hotspot generation and heat transfer relative to a simple physical mixture of Al/Ag-MOF, thus producing shorter ignition delay times and more efficient combustion. Thermal reactivity study indicated that the functionalization of the Ag-MOF shell changes the energy release process of the inner Al, which is accompanied by a thermite reaction. The synergistic effect of implantation of hypergolic MOF and high energy Al contributes to high specific impulses of 230-270 s over a wide range of oxidizer-to-fuel ratios.

Analysis of Efficacy and Safety of Small-Volume-Plasma Artificial Liver Model in the Treatment of Acute-On-Chronic Liver Failure

To explore the efficacy and safety of a small-volume-plasma artificial liver support system (ALSS) in the treatment of acute-on-chronic liver failure (ACLF). A retrospective analysis was performed. All ACLF patients received ALSS of plasma exchange & double plasma molecular absorb system (PE+DPMAS) treatment, and successfully completed this treatment. Patients were divided into small-volume and half-volume plasma groups. We compared the changes of the indicators on liver function, kidney function, blood coagulation function, and blood ammonia level before and after PE+DPMAS treatment; we compared the short-term and long-term curative effects between small-volume and half-volume plasma groups; and the factors influencing Week 4 and Week 12 mortality of ACLF patients were analyzed. The Week 4 improvement rates were 63.96 % and 66.86 % in the small-volume and half-volume plasma groups, respectively. The Week 12 survival rates in the small-volume-plasma and half-volume plasma groups were 66.72 % and 64.61 %, respectively. We found several risk factors affecting Week 4 and Week 12 mortality. Kaplan-Meier survival curves suggested no significant difference in Week 4 and Week 12 survival rates between the small-volume and half-volume plasma groups (P=0.34). The small-volume-plasma PE+DPMAS treatment could effectively reduce bilirubin and bile acids, and this was an approach with high safety and few complications, similar to the half-volume-plasma PE+DPMAS treatment. The small-volume-plasma PE+DPMAS has the advantage of greatly reducing the need for intraoperative plasma, which is especially of importance in times of shortage of plasma.

π-Electron Fluctuation-Induced P+ /C- Ambiphilic Interaction for Intramolecular CAr -H Bond Activation

Herein, we describe how computational mechanistic understanding has led directly to the discovery of new 2H-phosphindole for C-CAr bond activation and dearomatization reaction. We uncover an unexpected intramolecular C-H bond activation with a 2H-phosphindole derivative. This new intriguing experimental observation and further theoretical studies led to an extension of the reaction mechanism with 2H-phosphindole. Through DFT calculations, we confirm that within a five-membered ring, the polarizable PC3 unit orchestrates the formation of an electrophilic phosphorus atom (P+ ) and a nucleophilic carbon atom (C- ). This kinetically accessible ambiphilic phosphorus/carbon couple is spatially separated by geometric constraints, and their reactivity is modulated through structural resonance.

Nanobody-Based ImmunoPET for Hepatocellular Carcinoma

PURPOSE/OBJECTIVE(S)

HCC accounts for 75-90% of all primary liver cancers, the majority of which are treated with liver-directed therapy. Treatment response and recurrence are difficult to discern using conventional imaging with MR/CT. Tumor-selective PET imaging could help with clinical management in this setting. Here, we engineer HN3, a single-domain antibody (nanobody) specific to GPC3, a histopathologically-defining HCC marker, as an immunoPET agent. We compared both conventional and sortase-based site-specific modification methods for synthesizing HN3 immunoPET tracers.

MATERIALS/METHODS

Stochastic lysine conjugation with deferoxamine (DFO-NCS) was done to synthesize nHN3-DFO. ssHN3-DFO was engineered utilizing sortase-mediated conjugation of HN3 containing an LPETG C-terminal tag and a triglycine-DFO chelator. Biolayer interferometry (BLI) and radioligand saturation assays were done to determine binding affinity pre- and post-Zirconium-89 labeling. Following, PET/CT with a terminal 3-hour biodistribution was done in mice inoculated with isogenic A431 and A431-GPC3+ xenografts to determine conjugate specificity for GPC3. Finally, conjugates were evaluated in a HepG2 liver cancer model via ex vivo biodistribution studies and a comparative PET/CT study in mice bearing HepG2 tumors that were imaged with both [18F]FDG and 89Zr-ssHN3.

RESULTS

Both conjugates exhibited nanomolar binding affinity for GPC3 in vitro (11-30 nM for nHN3 and 10-15 nM for ssHN3). A431 and A431-GPC3+ PET/CT and biodistribution studies showed specificity to GPC3 by both probes, with more favorable tumor uptake by 89Zr-ssHN3 at 3 hours post-injection (14% IA/g vs. 7% IA/g for nHN3). Both tracers also displayed uptake in HepG2 (GPC3+) liver tumors, again with the site specifically conjugated probe having higher tumor accumulation and lower liver signal than the conventionally modified HN3 (7% IA/g vs. 5 % IA/g for tumor and 2% IA/g vs. 4% IA/g for liver at 1-hour post-injection). PET/CT studies in mice imaged with [18F]FDG and 89Zr-ssHN3 demonstrated more consistent tumor accumulation for the nanobody conjugate (4/4 mice had uptake by the tumor vs. 1/4 for FDG).

CONCLUSION

We successfully designed, synthesized, and characterized novel GPC3-selective nanobody PET probes that can image liver tumors in vivo. The site-specifically conjugated tracer showed more favorable biodistribution and pharmacokinetic properties, resulting in a much higher tumor: liver signal compared to 89Zr-nHN3. We also show the superiority of the 89Zr-ssHN3 imaging over conventional [18F]FDG, highlighting a clear advantage in using targeted tumor imaging for this cancer type. Successful translation of the site-specifically conjugated nanobody may ultimately aid in characterizing lesions following liver-directed therapy and allow for more comprehensive screening, early diagnosis, and post-treatment surveillance of HCC.

2H-Phosphindole-Enabled Dearomatization and [4+2] Cycloaddition of (Hetero)Arenes

The heavier main group multiple bonds offer an effective tool for small molecule activation. Transient 2H-phosphinidole working as a reactive phosphadiene system undergoes phospha-Diels-Alder reaction with a wide range of non-activated aromatic carbocycles and heterocycles, including naphthalene, anthracene, phenanthrene, furan, thiophene, pyrrole, pyridine, and benzo-fused heterocycles, affording concise access to a range of polycyclic fused rings feature with phosphorus at the bridgehead. These results demonstrate that non-activated (hetero)arenes are capable of acting as 2π systems in [4+2] cycloaddition with highly reactive 2H-phosphindole complex.

Increasing riverine export of dissolved organic carbon from China

River transport of dissolved organic carbon (DOC) to the ocean is a crucial but poorly quantified regional carbon cycle component. Large uncertainties remaining on the riverine DOC export from China, as well as its trend and drivers of change, have challenged the reconciliation between atmosphere-based and land-based estimates of China's land carbon sink. Here, we harmonized a large database of riverine in-situ measurements and applied a random forest model, to quantify riverine DOC fluxes (FDOC ) and DOC concentrations (CDOC ) in rivers across China. This study proposes the first DOC modeling effort capable of reproducing well the magnitude of riverine CDOC and FDOC , as well as its trends, on a monthly scale and with a much wider spatial distribution over China compared to previous studies that mainly focused on annual-scale estimates and large rivers. Results show that over the period 2001-2015, the average CDOC was 2.25 ± 0.45 mg/L and average FDOC was 4.04 ± 1.02 Tg/year. Simultaneously, we found a significant increase in FDOC (+0.044 Tg/year2 , p = .01), but little change in CDOC (-0.001 mg/L/year, p > .10). Although the trend in CDOC is not significant at the country scale, it is significantly increasing in the Yangtze River Basin and Huaihe River Basin (0.005 and 0.013 mg/L/year, p < .05) while significantly decreasing in the Yellow River Basin and Southwest Rivers Basin (-0.043 and -0.014 mg/L/year, p = .01). Changes in hydrology, play a stronger role than direct impacts of anthropogenic activities in determining the spatio-temporal variability of FDOC and CDOC across China. However, and in contrast with other basins, the significant increase in CDOC in the Yangtze River Basin and Huaihe River Basin is attributable to direct anthropogenic activities. Given the dominance of hydrology in driving FDOC , the increase in FDOC is likely to continue under the projected increase in river discharge over China resulting from a future wetter climate.

Synthesis and properties of photoluminescent phosphorus-doped triptycenes

A new class of phosphorus-doped triptycenes was designed and synthesized via a Diels-Alder reaction between alkynylphosphonates and anthracene, followed by oxidative cyclization. The packing interaction and molecular alignment in the single crystals revealed that the weak C-H⋯π (2.825 Å) interaction guides the self-assembly of phosphindole oxide iptycenes. The photophysical and electrochemical properties of these photoluminescent phosphorus-doped iptycenes were characterized to gain a deeper understanding of their fluorescence tunability. The presence of functional groups on the phenyl ring of the P-doped fin and the chemical environment of the P atom both had an effect on the fluorescence emission.

[Tumor antigen-loaded dendritic cells combined with cytokine-induced killer (CIK) enhance the killing activity of human esophageal cancer cells by promoting ASK1 activation]

Objective To clarify the effect and mechanism of tumor antigen-loaded dendritic cells (Ag-DCs) combined with cytokine-induced killers (CIKs) on the killing of esophageal cancer tumor cells. Methods Peripheral blood DCs and CIKs were induced and cultured, and the DCs were loaded with tumor antigen to obtain Ag-DCs, and Ag-DCs were co-cultured with CIKs. The experiment was divided into CIK group, DC combined with CIK group, Ag-DC combined with CIK group. Flow cytometry was used to detect the phenotype of cells. MTT assay was employed to determine the killing activity against EC9706 cells. Annexin V-FITC/PI double staining was used to detect the apoptosis rate of cells, immunofluorescence staining to detect the expression of phosphorylated apoptotic signal-regulated kinase 1 (p-ASK1) and Western blot analysis to detect the expression of ASK1 pathway related proteins. A nude mouse model of esophageal cancer transplantation tumor was constructed and divided into control group, DC combined with CIK group and Ag-DC combined with CIK group. The corresponding immune cells were injected into the tail vein for treatment and the tumor volume was measured every 2 days. After 21 days, all nude mice were sacrificed with the tumors taken out. HE staining was used to observe the tumor pathological changes and immunohistochemical staining was performed to detect the expression of ki67 and ASK1 in the tumor tissue. Results Comparedwith the CIK group alone and the DC combined with CIK group, the ratio of CD3⁺ CD8⁺ and CD3⁺ CD56⁺ in the cells significantly increased after Ag-DCs and CIKs co-culture, along with the increased killing rate of EC9706 cells, increased apoptosis rate of EC9706 cells, and the improved activation level of ASK1. Compared with the CIK group and the DC combined with CIK group, the growth of the transplanted tumor in nude mice treated with Ag-DCs combined with CIKs was significantly inhibited, and after 21 days, it was observed that the tumor tissue mass in this group was relatively smaller, with sparsely arranged cells in the tumor tissue and a decline in the positive rate of ki67 in tumor tissue, while the positive rate of ASK1 was significantly increased. Conclusion Co-cultivation of tumor antigen-loaded DCs with CIKs can significantly increase the killing activity of esophageal cancer tumor cells. The mechanism of action may be related to the activation of the ASK1 pathway.

Convergence and divergence emerging in climatic controls of polynomial trends for northern ecosystem productivity over 2000-2018

Recent rapid warming has caused uneven impacts on the composition, structure, and functioning of northern ecosystems. It remains unknown how climatic drivers control linear and non-linear trends in ecosystem productivity. Based on a plant phenology index (PPI) product at a spatial resolution of 0.05° over 2000-2018, we used an automated polynomial fitting scheme to detect and characterize trend types (i.e., polynomial trends and no-trends) in the yearly-integrated PPI (PPI_INT) for northern (> 30°N) ecosystems and their dependence on climatic drivers and ecosystem types. The averaged slope for the linear trends (p < 0.05) of PPI_INT was positive across all the ecosystems, among which deciduous broadleaved forests and evergreen needle-leaved forests (ENF) showed the highest and lowest mean slopes, respectively. More than 50% of the pixels in ENF, arctic and boreal shrublands, and permanent wetlands (PW) had linear trends. A large fraction of PW also showed quadratic and cubic trends. These trend patterns agreed well with estimates of global vegetation productivity based on solar-induced chlorophyll fluorescence. Across all the biomes, PPI_INT in pixels with linear trends showed lower mean values and higher partial correlation coefficients with temperature or precipitation than in pixels without linear trends. Overall, our study revealed the emergence of latitudinal convergence and divergence in climatic controls on the linear and non-linear trends of PPI_INT, implying that northern shifts of vegetation and climate change may potentially increase the non-linear nature of climatic controls on ecosystem productivity. These results can improve our understanding and prediction of climate-induced changes in plant phenology and productivity and facilitate sustainable management of ecosystems by accounting for their resilience and vulnerability to future climate change.

[A semi-supervised material quantitative intelligent imaging algorithm for spectral CT based on prior information perception learning]

OBJECTIVE

To propose a semi-supervised material quantitative intelligent imaging algorithm based on prior information perception learning (SLMD-Net) to improve the quality and precision of spectral CT imaging.

METHODS

The algorithm includes a supervised and a self- supervised submodule. In the supervised submodule, the mapping relationship between low and high signal-to-noise ratio (SNR) data was constructed through mean square error loss function learning based on a small labeled dataset. In the self- supervised sub-module, an image recovery model was utilized to construct the loss function incorporating the prior information from a large unlabeled low SNR basic material image dataset, and the total variation (TV) model was used to to characterize the prior information of the images. The two submodules were combined to form the SLMD-Net method, and pre-clinical simulation data were used to validate the feasibility and effectiveness of the algorithm.

RESULTS

Compared with the traditional model-driven quantitative imaging methods (FBP-DI, PWLS-PCG, and E3DTV), data-driven supervised-learning-based quantitative imaging methods (SUMD-Net and BFCNN), a material quantitative imaging method based on unsupervised learning (UNTV-Net) and semi-supervised learning-based cycle consistent generative adversarial network (Semi-CycleGAN), the proposed SLMD-Net method had better performance in both visual and quantitative assessments. For quantitative imaging of water and bone materials, the SLMD-Net method had the highest PSNR index (31.82 and 29.06), the highest FSIM index (0.95 and 0.90), and the lowest RMSE index (0.03 and 0.02), respectively) and achieved significantly higher image quality scores than the other 7 material decomposition methods (P < 0.05). The material quantitative imaging performance of SLMD-Net was close to that of the supervised network SUMD-Net trained with labeled data with a doubled size.

CONCLUSIONS

A small labeled dataset and a large unlabeled low SNR material image dataset can be fully used to suppress noise amplification and artifacts in basic material decomposition in spectral CT and reduce the dependence on labeled data-driven network, which considers more realistic scenario in clinics.

Environmental assessment of landfill gas mitigation using biocover and gas collection with energy utilisation at aging landfills

A life cycle-based environmental assessment was conducted on the mitigation of landfill gas emissions, by implementing biocover and gas collection along with energy utilisation at aging landfills. Based on recent studies about gas generation at Danish landfills, the efficiency of the mitigation technologies involved and the composition of substituted energy production, 15 scenarios were modelled using the EASETECH life cycle assessment model, through which potential environmental impacts in the category "Climate change" were calculated. In all scenarios, biocover and gas collection systems with energy utilisation led to significant environmental improvements compared to the baseline scenario with no emission mitigation action. Scenarios representing biocovers with methane oxidation efficiencies between 70 and 90 % were environmentally superior in terms of climate change impact - in comparison to scenarios with 20-30 years of gas collection and energy utilisation (collection efficiencies between 40 and 80 %). Combining gas collection with energy utilisation and the subsequent installation of a biocover saw major improvements in comparison to where only gas collection and energy utilisation were in effect. Overall, it can be concluded that a biocover under the given assumptions is environmentally more appropriate than gas collection and utilisation at aging landfills, mainly due to methane emissions escaping through the landfill cover during and after the gas collection period playing a crucial role in the latter situation. Maintaining high methane oxidation efficiency for a biocover throughout the lifetime of a landfill is vital for reducing environmental impacts.

Estimation of dissolved organic carbon from inland waters at a large scale using satellite data and machine learning methods

Dissolved Organic Carbon (DOC) in inland waters plays an essential role in the global carbon cycle and has significant public health effects. Machine learning (ML) together with remote sensing has emerged as a powerful and promising combination to quantify water quality parameters from space. However, inland water sample data for DOC is limited. Hence, little is known about the potential to quantify DOC content in inland waters, especially over large-scale areas. This study presents the first attempt to estimate DOC in inland waters over a large-scale area using satellite data and ML methods with the newly published open-source dataset AquaSat. Four ML approaches, namely Random Forest Regression (RFR), Support Vector Regression (SVR), Gaussian Process Regression (GPR), and a Multilayer Backpropagation Neural Network (MBPNN) were trained using more than 16 thousand samples across the continental United States matched with satellite data from Landsat 5, 7 and 8 missions. Satellite data from the Landsat missions were further extended with environmental data from the ERA5-Land product and used as input to train the ML algorithms. Our results show that including environmental data as inputs considerably improved the prediction of DOC for all ML algorithms, with GPR showing the most promising performance results with moderate estimation errors (RMSE: 4.08 mg/L). Permutation feature importance analysis showed that the wavelength range in the visible Green band (from Landsat) and the monthly average air temperature (from ERA5-Land) were the most important variables for the ML approaches. The results demonstrate the predictive strength of GPR and its useful feature to derive per pixel standard deviations for detailed analysis. Our results further highlight the important role of considering environmental processes to explain DOC variations over large scales. The application and performance of the GPR in mapping spatiotemporal variations of DOC in an entire water body were discussed by taking Lake Okeechobee (the 8^th largest freshwater lake in the U.S.) as an illustrative example. While performance evaluation showed that DOC concentrations can be retrieved with adequate accuracy, algorithm development was challenged by the heterogenous nature of large-scale open source in situ data, issues related to atmospheric correction, and the low spatial and temporal resolution of the environmental predictors. This research demonstrates how open source, large-scale datasets like AquaSat in combination with ML and satellite remote sensing can make research toward large-scale estimation of inland water DOC more realistic while highlighting its remaining limitations and challenges.

Phosphorus-Involved Wagner-Meerwein Rearrangement of Phosphiranes: An Entry to Four-Membered Phosphacycles

Phosphenium ions [R₂P]⁺ are important and highly reactive dicoordinate phosphorus species. Herein, we report a rearrangement of the carbocation into the phosphenium cation driven by ring strain. This phosphorus-involved Wagner-Meerwein rearrangement pathway converted the 1-acylphosphirane complex into phosphetane and 1,2-dihydrophosphete derivatives depending on the reaction temperature. The generation of the intermediate phosphenium cation was identified by the intramolecular reaction with ether, which also disclosed its strong Lewis acidity. This work expands the boundary of the phosphorus-carbon analogy.

Rigid P-Chiral Phosphorus Ligands for Highly Selective Palladium-Catalyzed (4+2) and (4+4) Annulations

We developed novel shackled P-chiral ligands based on 1-phosphanorbornenes and oxazolines. They were subsequently evaluated in palladium-catalyzed (4+2) annulations, producing enantioenriched tetrahydropyran scaffolds in good yields with high site selectivity and enantioselectivity. Moreover, chemoselective (4+4) products were also achieved by using acyclic imines. In addition, density functional theory calculations were performed to afford the energy profile of the Michael addition step and ring formation step. This demonstrated that the enantioselective (4+2) annulations and the chemoselective reaction between (4+2) and (4+4) products were mostly under thermodynamic control.

Multi-parameter influenced acquisition model with an in-orbit jitter for inter-satellite laser communication of the LCES system

With the development of large low earth orbit (LEO) communication constellations, the efficiency of laser inter-satellite link (ISL) establishing become the bottleneck for subsequent large-scale launch and rapid networking applications of LEO communication constellations. Hence, we establish the pointing jitter error structure of LEO communication experiment satellites (LCES) system. The error structure can be used to trace the source of errors and evaluate the in-orbit jitter. And we derive an analytical expression of the acquisition probability density function (PDF) which comprehensively considering the influence of the scanning region, the pointing jitter error, the overlap factor and the in-orbit jitter error. The multi-parameter influenced acquisition model is validated by Monte Carlo (MC) simulations and semi-physical tests. The results reveals that the multi-parameter influenced acquisition model can be used to guide the in-orbit ISL establishing.

One Stone Three Birds: Regiodivergent Access to Amino-Substituted Benzophospholes and Their Structure-Property Relationships

Three series new NH₂-benzophosphole oxides were synthesized from cycloaddition of o-aminophenyl phosphine oxide with alkynes. The relationship between the location of the amino group and the photophysical properties were studied by absorption and emission spectroscopies and theoretical calculation. 4-NH₂-benzophosphole oxides show strong fluorescence emission and high fluorescence quantum efficiency. This "One stone three birds" process provides rapid access to multiple organophosphorus-based luminogens for the structure-property relationship study.

Activation of CS2 with the 2H-Phosphindole Complex to Construct P,S-Polycycles

The activation of CS₂ by the 2H-phosphindole complex with a low-coordinate phosphadiene moiety is reported. The successive hetero-Diels-Alder reaction between 2H-phosphindoles and CS₂ constructs two bridged rings and one spirocycle simultaneously, affording structurally complex P,S-polycyclic products. The two 2H-phosphindoles approach the C═S bond in a head-to-head disposition to minimize steric hindrance. This work reveals the unique reactivity of low-coordinate organophosphorus species and their potential applications in small molecule activation.

Dearomatization [4+2] Cycloaddition of Nonactivated Benzene Derivatives

Dearomatization reactions have recently emerged as a powerful tool for the rapid buildup of molecular complexity. Here, an unparalleled thermal dearomatization [4+2] cycloaddition reaction between benzene derivatives and a 2H-phosphindole tungsten complex was reported. The unique reactivity of the in situ-generated 2H-phosphindole complex toward benzene was revealed by density functional theory calculations. We thus provide new insights into the dearomatization of nonactivated arenes and pave the way for the manipulation of the dearomatization for further applications.

Improving generalisation capability of artificial intelligence-based solar radiation estimator models using a bio-inspired optimisation algorithm and multi-model approach

One way of reducing environmental pollution is to reduce our dependence on fossil fuels by replacing them with solar radiation (Rs), which is one of the main sources of clean and renewable energy. In this study, daily Rs values at seven meteorological stations in Iran (Ahvaz, Isfahan, Kermanshah, Mashhad, Bandar Abbas, Kerman and Tabriz) over 2010-2019 were estimated using empirical models, support vector machine (SVM), SVM coupled with cuckoo search algorithm (SVM-CSA) and multi-model approach in the form of two structures. In structure 1, data from each station were divided into training and testing sets. In structure 2, data from the former four stations were used for model training, and those from the latter three stations were used to test the models. The results showed that using meteorological parameters improved estimation accuracy compared with the use of geographical parameters for both SVM and SVM-CSA models. Coupling the CSA to SVM did improve the accuracy of radiation estimates, reducing RMSE by up to 38% (Kermanshah station) and 36% (Tabriz station) for the first structure and about 42.4% (Tabriz station) for the second. Performance analysis of the models over three intervals including, the first, middle and last third of measured radiation values at each station showed that for both structures (except at Tabriz station), the best model performance in under- and over-estimation sets of radiation values was obtained, respectively, in the first third interval (first structure, Mashhad station, RMSE = 28.39 J.cm^-2.day^-1) and the last third interval (first structure, Bandar Abbas station, RMSE = 12.23 J.cm^-2.day^-1). Determining the effects of climate change on Rs estimation and using remotely sensed data as inputs of the models could be considered as future works.

Methotrexate/mifepristone-combined with embryo removal in the treatment of caesarean scar pregnancy

OBJECTIVE

The aim of this study was to compare the effect of different administration modalities of methotrexate (MTX)/mifepristone in the initial medication stage, followed by embryo transfer in the treatment of caesarean scar pregnancy (CSP).

PATIENTS AND METHODS

A retrospective analysis of 66 CSP patients who received treatment in our hospital from January 2015 to July 2021 was performed, and participants were divided into three groups: Group one (n=14) received mifepristone followed by embryo removal treatment, Group two (n=29) received MTX followed by embryo removal, and Group three (n=23) received a methotrexate/mifepristone combined treatment followed by embryo removal. The basic findings were analysed, along with the curative effects between the three groups. Risk factors predicting additional treatment after initial intervention failure were analysed.

RESULTS

There were statistically significant differences in gestational age, hospitalization days, costs, myometrial thickness, cardiac activity, and mean sac diameter between groups (p<0.05) after grouping by eight weeks. The initial intervention success rates were 92.86%, 89.66%, and 65.22% in Group one, two, and three, respectively (p<0.05), while the complication rates were 14.29%, 6.90%, and 26.87%, respectively (p>0.05). After grouping according to eight weeks of gestational age, the difference in initial serum β-hCG between Group two and three was statistically significant (p<0.05). Mean sac diameter was a risk factor for additional treatment after initial intervention failure, with an odds ratio of 1.113 (p<0.05). A cut-off of 22.75 mm was a preferable indicator.

CONCLUSIONS

MTX/mifepristone followed by embryo removal is a reliable way to treat CSP. Mean sac diameter was a risk factor for additional treatment after initial intervention failure.

Insight into fragmentation of a phosphirane to form phosphinidene complexes: an illustration with the 1-phenylselenylphosphirane W(CO)5 complex

Density functional theory (DFT) calculations with 1-phenylselenylphosphirane complex 1 provide an insight into phosphirane fragmentation to phosphinidene complexes. FMO and ELF analyses show that the cleavage of two P-C σ bonds of phosphirane proceeds via an asynchronous concerted pathway. Transient [PhSeP-W(CO)₅] was generated by dissociation of 1 at 90 °C and trapped with different reagents. The 1-phenoxylphosphirane complex undergoes [1 + 2] retroaddition at a comparatively higher temperature which implies that the lone pair of the adjacent atom center of phosphorus plays a major role in phosphirane fragmentation.

Resonance-Mediated Dynamic Modulation of Perovskite Crystallization for Efficient and Stable Solar Cells

Manipulating perovskite crystallization to prepare high-quality perovskite films is the key to achieving highly efficient and stable perovskite solar cells (PSCs). Here, a dynamic strategy is proposed to modulate perovskite crystallization using a resonance hole-transporting material (HTM) capable of fast self-adaptive tautomerization between multiple electronic states with neutral and charged resonance forms for mediating perovskite crystal growth and defect passivation in situ. This approach, based on resonance variation with self-adaptive molecular interactions between the HTM and the perovskite, produces high-quality perovskite films with smooth surface, oriented crystallization, and low charge recombination, leading to high-performance inverted PSCs with power conversion efficiencies approaching 22% for small-area devices (0.09 cm² ) and up to 19.5% for large-area devices (1.02 cm² ). Also, remarkably high stability of the PSCs is observed, retaining over 90%, 88%, or 83% of the initial efficiencies in air with relative humidity of 40-50%, under continuous one-sun illumination, or at 75 °C annealing for 1000 h without encapsulation.

Intramolecular Activation of Enones by Electrophilic Phosphinidene Complexes to Construct 2-Phosphafurans

Herein, we report a facile and highly atom-economic approach to 2-phosphafurans by using simple 2-chloroethylphosphine and acetylenic ketones. The key step of this protocol utilizes the Lewis acidity of electrophilic phosphinidenes to induce an intramolecular cyclization with enones. Dearomative hetero-Diels-Alder reactions of 2-phosphafurans provide two series of bicyclic phosphacycles. This rare synthetic application of Lewis acidity of electrophilic phosphinidene complexes represents a new frontier of phosphinidene chemistry.

Tandem [5 + 1]/[8 + 2] cycloaddition reactions involving phosphiranes and tropones: facile access to 6,5,7-fused tricyclic skeletons

Tandem [5 + 1] carbonyl cyclization/[8 + 2] cycloaddition reactions of phosphiranes and tropones were developed as a straightforward method to access 6,5,7-fused tricyclic scaffolds.

Gestational bisphenol A exposure impairs hepatic lipid metabolism by altering mTOR/CRTC2/SREBP1 in male rat offspring

Lipid metabolism is an important biochemical process in the body. Recent studies have found that environmental endocrine disruptors play an important role in the regulation of lipid metabolism. Bisphenol A (BPA), a common environmental endocrine disruptor, has adverse effects on lipid metabolism, but the mechanism is still unclear. This study aimed to investigate the effects of gestational BPA exposure on hepatic lipid metabolism and its possible mechanism in male offspring. The pregnant Sprague-Dawley rats were exposed to BPA (0, 0.05, 0.5, 5 mg/kg/day) from day 5 to day 19 of gestation to investigate the levels of triglyceride (TG) and total cholesterol (TC), and the expression of liver lipid metabolism-related genes in male offspring rats. The results showed that compared with the control group, the TG and TC levels in serum and liver in BPA-exposed groups was increased. And the expressions of liver fatty acid oxidation related genes, such as peroxisome proliferators-activated receptor α (PPARα) and carnitine palmitoyl transferase 1α (CPT1α), were down-regulated. However, the expressions of fatty acid synthesis related genes, such as sterol regulatory element binding proteins 1 (SREBP-1), acetyl-CoA carboxylase 1 (ACC1), fatty acid synthase (FAS) and stearoyl-CoA desaturase 1 (SCD-1), were up-regulated. The increased protein levels of mTOR and p-CRTC2 suggested that CREB-regulated transcription coactivator 2 (CRTC2) might be an important mediator in the mTOR/SREBP-1 pathway. In conclusion, these results demonstrated that mTOR/CRTC2/SREBP-1 could be affected by gestational BPA exposure, which may involve in the lipid metabolic disorders in later life.

Diastereodivergent synthesis of fully disubstituted spiro[indoline-3,2′-pyrrolidin]-2-ones via tuneable Lewis base/Brønsted base-promoted (3 + 2) cycloadditions

We have developed unique base-promoted diastereoselective (3 + 2) cycloadditions. A diastereodivergent synthesis of fully disubstituted spiro[indoline-3,2′-pyrrolidin]-2-ones was realized by tuning a Lewis base/Brønsted base.

Cooperative Palladium-Catalyzed and P(NEt2)3-Mediated (4+1) Annulation of Isatins with 2-Hydroxymethylallylcarbonates

P(NR2)3-promoted transformations of isatins with electron-withdrawing alkenes have received consistently attention over the last decades. However, no example involving chemical transformations of nonactivated or weakly activated alkenes is discovered in...

Ligand-dependent, palladium-catalyzed stereodivergent synthesis of chiral tetrahydroquinolines

The most fundamental tasks in asymmetric synthesis are the development of fully stereodivergent strategies to access the full complement of stereoisomers of products bearing multiple stereocenters. Although great progress has been made in the past few decades, developing general and practical strategies that allow selective generation of any diastereomer of a reaction product bearing multiple stereocentres through switching distinct chiral catalysts is a significant challenge. Here, attaining precise switching of the product stereochemistry, we develop a novel P-chirogenic ligand, i.e.YuePhos, which can be easily derived from inexpensive and commercially available starting materials in four chemical operations. Through switching of three chiral ligands, an unprecedented ligand-dependent diastereodivergent Pd-catalyzed asymmetric intermolecular [4 + 2] cycloaddition reaction of vinyl benzoxazinanone with α-arylidene succinimides was developed. This novel method provides an efficient route for the stereodivergent synthesis of six stereoisomers of pyrrolidines bearing up to three adjacent stereocenters (one quaternary center). Despite the anticipated challenges associated with controlling stereoselectivity in such a complex system, the products are obtained in enantiomeric excesses ranging up to 98% ee. In addition, the synthetic utilities of optically active hexahydrocarbazoles are also shown.

An unprecedented ligand-dependent stereodivergent Pd-catalyzed asymmetric intermolecular [4 + 2] cycloaddition reaction of vinyl benzoxazinanone with α-aryliene succinimides was developed.

Improving streamflow simulation by combining hydrological process-driven and artificial intelligence-based models

Accurate and timely monitoring of streamflow and its variation is crucial for water resources management in watersheds. This study aimed at evaluating the performance of two process-driven conceptual rainfall-runoff models (HBV: Hydrologiska Byråns Vattenbalansavdelning, and NRECA: Non Recorded Catchment Areas) and seven hybrid models based on three artificial intelligence (AI) methods (adaptive neuro-fuzzy inference system (ANFIS), support vector machine (SVM), and group method of data handling (GMDH)) in simulating streamflow in four river basins in Indonesia. HBV and NRECA were developed based on precipitation data. Various combinations of 1-month lagged precipitation data together with outputs of HBV and NRECA were used for developing ANFIS and SVM models, and the best results of ANFIS and SVM formed the inputs to GMDH. Results showed that AI-based hybrid models have generally led to more accurate streamflow estimates compared with HBV and NRECA, and the GMDH model had the best performance at Cipero, Kedungdowo, Notog, and Sukowati stations, with RMSEs of 12.21, 6.07, 20.35, and 24.2 m³ s^-1, respectively. More accurate estimation of peak values in training set at Cipero and Sukowati stations, and in both training and testing sets at Kedungdowo station was another advantage of GMDH. Hybrid models based on AI methods can be suitable alternatives to hydrological models, particularly in watersheds where there is a lack of measured data (e.g. climatic parameters, land cover-plant growth data, soil data, stream conditions, and properties of groundwater aquifers), provided that appropriate inputs are used.

Mapping regional surface water volume variation in reservoirs in northeastern Brazil during 2009-2017 using high-resolution satellite images

The multiple-year drought that started in 2011 and reached climax in 2015 was the most severe and prolonged one in the semiarid northeastern (NE) Brazil in recent decades. This study aimed to investigate the reservoir surface water volume (SWV) variation in NE Brazil from 2009 to 2017 in four representative regions covering a total area of approximately 10,000 km² there and encompassing 2,140 reservoirs (areas range from 0.003 to 21 km²). High-resolution (10 m) digital elevation models (DEMs) were generated from the TanDEM-X data acquired during October-December 2015 to represent the reservoirs' bathymetric maps. The water extents in the reservoirs were delineated from high-resolution (6.5 m) RapidEye images acquired during 2009-2017. The combination of the aforementioned two variables yielded reservoir SWV with an accuracy of 0.64 × 10⁶-1.06 × 10⁶ m³, corresponding to 3.1%-5.6% of the maximum SWV in the reservoirs. The results showed that: 1) 81%-99% of the reservoirs in the four regions were from the groups with maximum water extent <50 ha and contributed 2%-59% of the regional reservoir SWV. In contrast, 0.6%-20% of the reservoirs were from the group of >50 ha and contributed 40%-98% to the regional SWV; 2) From 2009 to 2017, reservoir SWV in the four regions decreased at the rates of 2.3 × 10⁶-17.8 × 10⁶ m³/year; and 3) The SWV in the reservoirs responded differently to the regional terrestrial water budget, i.e. the differences between precipitation and evapotranspiration (P-ET). This study filled the data gap of bathymetric maps for the 2140 reservoirs, regardless of their sizes and macrophyte coverage. The SWV variations derived in those reservoirs over a period covering the recent drought can support better preparedness for drought in NE Brazil and better understanding of the regional hydrology in semi-arid regions.

Design of 1-Phosphanorbornene Derivatives as Chiral Organocatalysts for Enantioselective (4 + 2) Annulation Reactions of γ-Benzyl Allenoates

Two novel diastereoisomeric P-chirogenic phosphine catalysts, i.e., JiaPhos, which can be easily derived from inexpensive and commercially available starting materials in five chemical operations (totally 4.16g scale), are introduced. To our delight, the JiaPhos catalysts display good performance in enantioselective (4 + 2) annulations involving 3-methylene-2-oxindoles and γ-benzyl allenoates, providing a wide range of 3,3'-spirocyclic oxindoles with good efficiency and enantioselectivity.

Phosphine-Catalyzed (4 + 2) Cycloaddition of Conjugated Dienes with Enones and Its Asymmetric Variant

Herein we reported a novel phosphine-catalyzed (4 + 2) cyclization reaction of electron-deficient conjugated dienes with enones to generate functionalized dihydropyran skeletons. A mechanistic investigation reveals that the reaction produces a new phosphonium zwitterion, which undergoes consecutive reactions. In addition, an asymmetric variant was developed by efficient and economical chiral phosphine catalysis.

FeCl2 Catalyzed Three-Component Reactions of Phospholes, Pyrrolidine, and Ketones (Aldehydes): Chemoselective Synthesis of 1-Phosphafulvenes

We have developed an unprecedented approach for the synthesis of transient 1-phosphafulvenes through three component reactions of phospholes. The generation of 1-phosphafulvenes was demonstrated by in situ [6 + 4] cycloaddition with 2H-phospholes and [6 + 6] self-dimerization. The [6 + 4] and [6 + 6] reaction pathway could be modulated by the starting ketones and aldehydes. The construction of 1-phosphafulvenes is illustrated by a proposed mechanism combining nucleophilic addition of phospholide to the iminium or isomerized azomethine ylide and a [1,5]-shift of phosphole.

Assessing glacier retreat and its impact on water resources in a headwater of Yangtze River based on CMIP6 projections

Glacier retreat caused by global warming alters the hydrological regime and poses far-reaching challenges to water resources and nature conservation of the headwater of Yangtze River, and its vast downstream regions with dense population. However, there is still lack of a robust modeling framework of the "climate-glacier-streamflow" in this water tower region, to project the future changes of glacier mass balance, glacier geometry, and the consequent impacts on runoff. Moreover, it is imperative to use the state-of-the-art sixth phase Coupled Model Intercomparison Project (CMIP6) to assess glacio-hydrology variations in future. In this study, we coupled a glacio-hydrological model (FLEX^G) with a glacier retreat method (Δh-parameterization) to simulate glacio-hydrological processes in the Dongkemadi Glacier (over 5155 m.a.s.l), which has the longest continuous glacio-hydrology observation on the headwater of Yangtze River. The FLEX^G-Δh model was forced with in-situ observed meteorological data, radar ice thickness, remote sensing topography and land cover data, and validated by measured runoff. The results showed that the model was capable to simulate hydrological processes in this glacierized basin, with Kling-Gupta efficiency (I_KGE) of daily runoff simulation 0.88 in calibration and 0.70 in validation. Then, forcing by the bias-corrected meteorological forcing from the eight latest CMIP6 Earth system models under two climate scenarios (RCP2.6 and RCP8.5), we assessed the impact of future climate change on glacier response and its hydrological effects. The results showed that, to the end of simulation in 2100, the volume of the Dongkemadi Glacier would continuously retreat. For the RCP2.6 and RCP8.5 scenarios, the glacier volume will decrease by 8.7 × 10⁸ m³ (74%) and 10.8 × 10⁸ m³ (92%) respectively in 2100. The glacier runoff will increase and reach to peak water around 2060 to 2085, after this tipping point water resources will likely decrease.

Recent Advances in Luminescent Annulated Borepins, Silepins, and Phosphepins

This review summarizes recent research on the molecular design, optical, and electronic properties of annulated borepins, silepins, and phosphepins, with emphasis on their structure–property relationships at the molecular level.

1 Introduction

2 Borepins

3 Silepins

4 Phosphepins

5 Summary and Outlook

Nonbenzenoid aromaticity of 1-phosphafulvenes: synthesis of phosphacymantrenes

The coordination chemistry of 1-phosphafulvenes was investigated by employing their [6 + 4] adducts or α-C₂-bridged biphospholes as a precursor. Unbridged phosphacymantrenes arise from 1-phosphafulvenes via proton abstraction. α-C₂-bridged biphosphacymantrenes are probably yielded by the reductive coupling of 1-phosphafulvene with Mn₂(CO)₁₀. The coordination behavior of 1-phosphafulvenes is comparable to that of pentafulvenes, which again demonstrates the phosphorus-carbon analogy in low-coordinate organophosphorus chemistry.