Direct Z-Scheme Heterostructure of Vertically Oriented SnS2 Nanosheet on BiVO4 Nanoflower for Self-Powered Photodetectors and Water Splitting.

The construction of nanostructured Z-scheme heterostructure is a powerful strategy for realizing high-performance photoelectrochemical (PEC) devices such as self-powered photodetectors and water splitting. Considering the band structure and internal electric field direction, BiVO4 is a promising candidate to construct SnS2 -based heterostructure. Herein, the direct Z-scheme heterostructure of vertically oriented SnS2 nanosheet on BiVO4 nanoflower is rationally fabricated for efficient self-powered PEC photodetectors. The Z-scheme heterostructure is identified by ultraviolet photoelectron spectroscopy, photoluminescence spectroscopy, PEC measurement, and water splitting. The SnS2 /BiVO4 heterostructure shows a superior photodetection performance such as excellent photoresponsivity (10.43 mA W-1 ), fast response time (6 ms), and long-term stability. Additionally, by virtue of efficient Z-scheme charge transfer and unique light-trapping nanostructure, the SnS2 /BiVO4 heterostructure also displays a remarkable photocatalytic hydrogen production rate of 54.3 µmol cm-2 h-1 in Na2 SO3 electrolyte. Furthermore, the synergistic effect between photo-activation and bias voltage further improves the PEC hydrogen production rate of 360 µmol cm-2 h-1 at 0.8 V, which is an order of magnitude above the BiVO4 . The results provide useful inspiration for designing direct Z-scheme heterostructures with special nanostructured morphology to signally promote the performance of PEC devices.

High-Performance Flexible Broadband Photoelectrochemical Photodetector Based on Molybdenum Telluride.

Flexible broadband photodetectors are desired but challenging to be fabricated for next-generation wearable intelligent optoelectronic devices. Considering the narrow bandgap and strong light absorption, molybdenum telluride (MoTe2 ) based photoelectrochemical photodetectors are successfully assembled by liquid phase exfoliation accompanied with the electrophoretic deposited method. This MoTe2 -based photodetector shows a broadband detection in ultraviolet-near-infrared band, long-term stability within 18000 s, and fast response in millisecond-level (response time≈19 ms, recovery time≈26 ms). More importantly, even though the MoTe2 photodetector is bent and twisted at a high degree for several hundred times, it still shows excellent flexibility with stable on-off switching characteristics. Additionally, this photodetector displays a good response for rotation angles in the range from 0° to 360°, and the extracted Iph maintain almost the same value approximately 0.97 µA cm-2 , suggesting an omnidirectional detection capability. This work demonstrates the proposed flexible photoanode shows a great potential in future broadband omnidirectional detection systems.

Uncertainty-based saltwater intrusion prediction using integrated Bayesian machine learning modeling (IBMLM) in a deep aquifer.

Data-driven machine learning approaches are promising to substitute physically based groundwater numerical models and capture input-output relationships for reducing computational burden. But the performance and reliability are strongly influenced by different sources of uncertainty. Conventional researches generally rely on a stand-alone machine learning surrogate approach and fail to account for errors in model outputs resulting from structural deficiencies. To overcome this issue, this study proposes a flexible integrated Bayesian machine learning modeling (IBMLM) method to explicitly quantify uncertainties originating from structures and parameters of machine learning surrogate models. An Expectation-Maximization (EM) algorithm is combined with Bayesian model averaging (BMA) to find out maximum likelihood and construct posterior predictive distribution. Three machine learning approaches representing different model complexity are incorporated in the framework, including artificial neural network (ANN), support vector machine (SVM) and random forest (RF). The proposed IBMLM method is demonstrated in a field-scale real-world "1500-foot" sand aquifer, Baton Rouge, USA, where overexploitation caused serious saltwater intrusion (SWI) issues. This study adds to the understanding of how chloride concentration transport responds to multi-dimensional extraction-injection remediation strategies in a sophisticated saltwater intrusion model. Results show that most IBMLM exhibit r values above 0.98 and NSE values above 0.93, both slightly higher than individual machine learning, confirming that the IBMLM is well established to provide better model predictions than individual machine learning models, while maintaining the advantage of high computing efficiency. The IBMLM is found useful to predict saltwater intrusion without running the physically based numerical simulation model. We conclude that an explicit consideration of machine learning model structure uncertainty along with parameters improves accuracy and reliability of predictions, and also corrects uncertainty bounds. The applicability of the IBMLM framework can be extended in regions where a physical hydrogeologic model is difficult to build due to lack of subsurface information.

Coherent injection photocurrent in bismuth sulfide film induced by one-plus-two photon absorption quantum interference.

Quantum interference (QuI) effect is a powerful method to generate and control the ultrafast photocurrent in semiconductors. We utilize two-color pulsed light excitation in bismuth sulfide (Bi2S3) film to induce the photocurrent through the QuI effect. Experimentally, the photocurrent is indirectly monitored using a standard terahertz (THz) time-domain spectroscopic system. Due to the QuI, an asymmetric photon injection occurs in Bi2S3 film, resulting in coherent injection current and subsequently THz wave generation. Our results on the pump pulse energy dependence of the THz electric field suggests that the THz wave generation process follows the third-order nonlinear optical process.

Temperature Influenced the Comammox Community Composition in Drinking Water and Wastewater Treatment Plants.

Nitrification is a pivotal step applied in water engineered systems for nitrogen removal. Temperature variation due to seasonal changes is a great challenge for maintaining nitrogen removal efficiency in water engineered ecosystems by affecting nitrifier activities. Research on the abundance, activity, and metabolic characteristics of nitrifiers can provide information for selecting suitable design parameters to ensure efficient nitrogen removal in different seasons. To date, the temperature-related niche separation of comammox, a newly discovered nitrifier with potential high-growth yield, has been rarely investigated. This study addressed the distribution of comammox and canonical nitrifying guilds in drinking water treatment plants (DWTPs) and wastewater treatment plants (WWTPs) in different seasons. qPCR-based surveys showed that comammox ubiquitously distributed and greatly outnumbered other ammonia-oxidizing prokaryotes in both DWTPs and WWTPs, except in Aug samples from DWTPs, suggesting the potential competitive advantage of AOA in summer. The nitrificans-like comammox and nitrosa-like comammox comprised the majority of the comammox community in DWTPs and WWTPs, respectively, and COD and NH4+ concentrations significantly contributed to the distinct comammox phylotype distribution between DWTPs and WWTPs. The temperature-related distribution pattern of the comammox community was observed at each site. Moreover, the network complex of comammox communities was highest in Dec at all the sites, possibly contributing to the survival of comammox community in low temperature conditions.

Abnormal regional homogeneity and its relationship with symptom severity in cervical dystonia: a rest state fMRI study.

BACKGROUND: Although several brain networks play important roles in cervical dystonia (CD) patients, regional homogeneity (ReHo) changes in CD patients have not been clarified. We investigated to explore ReHo in CD patients at rest and analyzed its correlations with symptom severity as measured by Tsui scale. METHODS: A total of 19 CD patients and 21 gender-, age-, and education-matched healthy controls underwent fMRI scans at rest state. Data were analyzed by ReHo method. RESULTS: Patients showed increased ReHo in the right cerebellum crus I and decreased ReHo in the right superior medial prefrontal cortex (MPFC). Moreover, the right precentral gyrus, right insula, and bilateral middle cingulate gyrus also showed increased ReHo values. A significantly positive correlation was observed between ReHo value in the right cerebellum crus I and symptom severity (p < 0.05). CONCLUSIONS: Our investigation suggested abnormal ReHo existed in brain regions of the "pain matrix" and salience network (the right insula and bilateral middle cingulate gyrus), the motor network (the right precentral gyrus), the cerebellum and MPFC and further highlighted the significance of these networks in the pathology of CD.

Measuring sustainability as distance to ideal position of economy, society and environment: Application to China's provincial water resources (2004-17).

Water is fundamental for life and hence, ensuring its sustainability is essential. Indices can be useful tools to monitor sustainability, understand trends and take necessary actions. China is one of the world's most water-strained countries, and herein, a spatially and temporally-replicable index is developed to measure the sustainability of water resources in its provinces (from 2004-17). Unlike previous indices that aggregate contributing indicators by taking their mean (weighted, unweighted, arithmetic, geometric, etc.), the present study proposes a distance-approach to measure sustainability - enabling it to circumvent concerns on choice of weights and aggregation method. This method of quantification is in conjunction with the 'tripartite' conceptualization of sustainability - which says that it is the equilibrium among the economy, society and environment. It is assumed that provinces can be plotted in a 3-dimensional plane using numeric values denoting their economic, social and environmental development. Thereafter, the measure of sustainability would be the distance of the province to the ideal point of development in these three dimensions. The economic, social and environmental dimensions of water resources are computed by choosing appropriate indicators and applying TOPSIS (Technique -for Order Preference by Similarity to Ideal Solution). The trends in indices over the years are analyzed using a modified Mann-Kendall test. Further, the indices are checked for any spatial correlation (among the provinces) using Moran's I. Lastly, factors (such as forest cover, fertilizer use and illiteracy) that may act as determinants of the indices are examined through panel regression. The results of the study provide an extensive view of water resources sustainability in China since the past decade, and can be useful for steering the direction of water policy actions in the future.

Dissolution monitoring of diclofenac sodium and codeine phosphate tablets using fibre optic chemical sensor assisted by dual-wavelength isosbestic point spectrophotometry.

The purpose of this investigation was to establish a mathematical model for determining the dissolution of diclofenac sodium and codeine phosphate simultaneously. Based on the dual-wavelength isosbestic point spectrophotometry, the dissolution of diclofenac sodium and codeine phosphate tablets was determined using Fiber-Optic Dissolution Test (FODT) instrument capable of real-time measurement. Dissolution curves showed that the dissolution process of diclofenac sodium was similar to that of codeine phosphate. The dissolution profile of diclofenac sodium and codeine phosphate at 45 min was concordant with that stated in Chinese pharmacopoeia. There was no significant difference between results obtained from FODT and HPLC (p>0.05). A fibre-optic dissolution test system assisted by the mathematical separation model of linear equations was able to detect the dissolution of diclofenac sodium and codeine phosphate simultaneously. The dissolution profiles and overall data, which can directly reflect the dissolution speed at each time point, can provide the basis for establishing standards for the quality evaluation of drugs.

Molecular Characteristics of Dissolved Organic Nitrogen and Its Interaction with Microbial Communities in a Prechlorinated Raw Water Distribution System.

Dissolved organic nitrogen (DON) represents a unique challenge in prechlorinated raw water distribution systems (PRWDSs) because of its contribution to the formation of harmful nitrogen-disinfection byproducts, influence upon biogeochemical processes, and unclear molecular characteristics. Here, Fourier transform ion cyclotron resonance mass spectrometry in combination with high-throughput sequencing was applied to elucidate the molecular changes of DON and biofilm microbial communities in a PRWDS in Yixing, China. Our study revealed that dynamic characteristics of DON are significantly correlated with the biofilm. The accumulation of refractory lignin-like compounds and CnHmOpN1 contributes to the higher recalcitrance molecular characteristics of DON in the effluent associated with Alphaproteobacteria, Planctomycetes, and Bacteroidetes. Additionally, with the help of prechlorination, the biofilm may change the DON characteristics and lead to higher oxygenation, higher m/z, and lower saturation during transportation. Despite the promotion of CnHmOpN1 and CnHmOpN3 at the early stage, we suggest that appropriate concentration of chlorine can add to the front end of raw water distribution pipes. Prechlorination may control the nitrification process and stabilize the rapid growth of diversity and concentration of low molecular weight DON, especially the refractory CnHmOpN1 in the effluent, which may help to improve treatment efficiency of drinking water treatment plants.

100 m/500 Mbps underwater optical wireless communication using an NRZ-OOK modulated 520 nm laser diode.

In this paper, we proposed and experimentally demonstrated a long-distance high-speed underwater optical wireless communication (UOWC) system in a laboratory environment by using a low-cost green laser diode (LD) and power-efficient non-return-to-zero on-off keying (NRZ-OOK) modulation. The system successfully achieved a data rate of 500 Mbps through a 100 m tap-water channel by using a pigtailed single-mode fiber 520 nm green LD. The tap water was measured to have an attenuation coefficient comparable to pure seawater. The measured system bit error rate (BER) value of 2.5 × 10-3 was below the forward error correction (FEC) limit of 3.8 × 10-3 with 7% overhead. The distance can be extended if the received optical power is allowed to reduce to the minimum power to meet the data rate requirement. Based on the measured minimum required power and the power decay model in the water channel, the transmission performance was predicted to be 146 m/500 Mbps and 174 m/100 Mbps.

Prescribing patterns of coronary artery aneurysm in Taiwan.

BACKGROUND: Coronary artery aneurysm (CAA) is a rare disease, and there are limited data on prescribing patterns for CAA. The aim of our study was to investigate prescribing patterns for CAA in Taiwan via the National Health Insurance Research Database (NHIRD). METHODS: We included all CAA patients in Taiwan from 2005 to 2011. Data from 1 year before and after the CAA diagnosis were used to analyze examinations, comorbidities and prescribing patterns. RESULTS: A total of 1397 patients diagnosed with CAA were enrolled in our study. Most pediatric patients with CAA were diagnosed with Kawasaki disease (95.7%). In pediatric CAA patients, the utilization rates of aspirin and gamma globulins were 82.9 and 53.6%, respectively, after CAA diagnosis. Among the antithrombotic agents, aspirin was used most commonly, followed by dipyridamole (16.9%), heparin (5.8%) and warfarin (4.6%). In adult CAA patients, common comorbidities included hypertension (63.4%), hyperlipidemia (39.6%), and diabetes mellitus (26.1%). Coronary atherosclerosis was identified in 72.5% of adult patients after CAA diagnosis. Antithrombotic agents, particularly aspirin, clopidogrel and heparin, were prescribed more frequently after CAA diagnosis. Among the prescribed medications, aspirin (75.8%), ß-blockers (48.3%), statins (47.6%), metformin (14.4%), sulfonylureas (14.4%) and isosorbide mononitrate (32.9%) were frequently observed in each category. CONCLUSIONS: Kawasaki disease was the main cause of CAA in pediatric patients, and coronary artery disease was the most common comorbidity in adult CAA patients. The most commonly used antithrombic agent after CAA diagnosis was aspirin in both adult and pediatric patients.

Effects of Rate-Limited Mass Transfer on Modeling Vapor Intrusion with Aerobic Biodegradation.

Most of the models for simulating vapor intrusion accept the local equilibrium assumption for multiphase concentration distributions, that is, concentrations in solid, liquid and vapor phases are in equilibrium. For simulating vapor transport with aerobic biodegradation controlled by counter-diffusion processes, the local equilibrium assumption combined with dual-Monod kinetics and biomass decay may yield near-instantaneous behavior at steady state. The present research investigates how predicted concentration profiles and fluxes change as interphase mass transfer resistances are increased for vapor intrusion with aerobic biodegradation. Our modeling results indicate that the attenuation coefficients for cases with and without mass transfer limitations can be significantly different by orders of magnitude. Rate-limited mass transfer may lead to larger overlaps of contaminant vapor and oxygen concentrations, which cannot be simulated by instantaneous reaction models with local equilibrium mass transfer. In addition, the contaminant flux with rate-limited mass transfer is much smaller than that with local equilibrium mass transfer, indicating that local equilibrium mass transfer assumption may significantly overestimate the biodegradation rate and capacity for mitigating vapor intrusion through the unsaturated zone. Our results indicate a strong research need for field tests to examine the validity of local equilibrium mass transfer, a widely accepted assumption in modeling vapor intrusion.

Rational Sine-Gordon expansion method to analyze the dynamical behavior of the time-fractional phi-four and (2 + 1) dimensional CBS equations.

This study uses the rational Sine-Gordon expansion (RSGE) method to investigate the dynamical behavior of traveling wave solutions of the water wave phenomena for the time-fractional phi-four equation and the (2 + 1) dimensional Calogero-Bogoyavlanskil schilf (CBS) equation based on the conformable derivative. The technique uses the sine-Gordon equation as an auxiliary equation to generalize the well-known sine-Gordon expansion. It adopts a more broad strategy, a rational function rather than a polynomial one, of the solutions of the auxiliary equation, in contrast to the traditional sine-Gordon expansion technique. Several explanations for hyperbolic functions may be produced using the previously stated approach. The approach mentioned above is employed to provide diverse solutions of the time-fractional phi-four equation and the (2 + 1) dimensional CBS equations involving hyperbolic functions, such as soliton, single soliton, multiple-soliton, kink, cusp, lump-kink, kink double-soliton, and others. The RSGE approach enhances our comprehension of nonlinear processes, offers precise solutions to nonlinear equations, facilitates the investigation of solitons, propels the development of mathematical tools, and is applicable in many scientific and technical fields. The solutions are graphically shown in three-dimensional (3D) surface and contour plots using MATLAB software. All screens display the absolute wave configurations in the resolutions of the equation with the proper parameters. Furthermore, it can be deduced that the physical properties of the found solutions and their characteristics may help us comprehend how shallow water waves move in nonlinear dynamics.

Dynamical behavior of water wave phenomena for the 3D fractional WBBM equations using rational sine-Gordon expansion method.

To examine the dynamical behavior of travelling wave solutions of the water wave phenomenon for the family of 3D fractional Wazwaz-Benjamin-Bona-Mahony (WBBM) equations, this work employs the rational Sine-Gordon expansion (RSGE) approach based on the conformable fractional derivative. The method generalizes the well-known sine-Gordon expansion using the sine-Gordon equation as an auxiliary equation. In contrast to the conventional sine-Gordon expansion method, it takes a more general approach, a rational function rather than a polynomial one of the solutions of the auxiliary equation. The method described above is used to generate various solutions of the WBBM equations for hyperbolic functions, including soliton, singular soliton, multiple-soliton, kink, cusp, lump-kink, kink double-soliton, etc. The RSGE method contributes to our understanding of nonlinear phenomena, provides exact solutions to nonlinear equations, aids in studying solitons, advances mathematical techniques, and finds applications in various scientific and engineering disciplines. The answers are graphically shown in three-dimensional (3D) surface plots and contour plots using the MATLAB program. The resolutions of the equation, which have appropriate parameters, exhibit the absolute wave configurations in all screens. Furthermore, it can be inferred that the physical characteristics of the discovered solutions and their features may aid in our understanding of the propagation of shallow water waves in nonlinear dynamics.

Epidemiology of Osteoporosis in Patients with Chronic Obstructive Pulmonary Disease in Taiwan.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is a preventable and treatable chronic condition characterized by progressive, partially reversible airflow obstruction. Osteoporosis represents a significant comorbidity in individuals with COPD. However, the incidence and prevalence of osteoporosis among the COPD population remain unclear in Taiwan. Therefore, our objective is to investigate the incidence and prevalence of osteoporosis in patients with COPD. METHODS: In this cross-sectional study, we enrolled a COPD population retrieved from the Taiwan National Health Insurance Research Database (NHIRD) spanning the years 2003 to 2016. Osteoporosis patients were identified using diagnosis codes. The study included newly diagnosed COPD patients from 2003 to 2016. The case group comprised patients who developed osteoporosis or osteoporotic fractures after their COPD diagnosis. We calculated the prevalence and incidence of osteoporosis in individuals with COPD and conducted trend tests. RESULTS: A total of 1,297,579 COPD patients were identified during the period from 2003 to 2016, with 275,233 of them in the osteoporosis group. The average prevalence of osteoporosis among individuals with COPD was 21.21% from 2003 to 2016 in Taiwan. The number of osteoporosis cases increased from 6,727 in 2003 to 24,184 in 2016. The prevalence of osteoporosis among COPD patients increased from 3.62% in 2003 to 18.72% in 2016. The number of osteoporosis cases among individuals with COPD continued to rise over the years, reaching its highest point in 2016 with 24,184 new cases. The incidence of osteoporosis fluctuated during the study period but generally remained around 3,000 cases per 100,000 person-years. Notably, there was a significant upward trend in incidence from 2003 to 2006, after which the trend stabilized and remained relatively constant. CONCLUSIONS: Our study highlights an increase in both the prevalence and incidence of osteoporosis in individuals with COPD. Given the significant medical, economic, and social implications associated with osteoporosis, a comprehensive and robust assessment of its healthcare burden can offer valuable insights for healthcare system planning and policymaking.

MZB1-mediated IgA secretion suppresses the development and progression of colorectal cancer triggered by gut inflammation.

Colorectal cancer (CRC) ranks among the top causes of mortality globally. Gut inflammation is one crucial risk factor that augments CRC development since patients suffering from inflammatory bowel disease have an increased incidence of CRC. The role of immunoglobulin (Ig)A in maintaining gut homeostasis and preventing inflammation has been well established. Our earlier work demonstrated that the marginal zone and B1 cell-specific protein (MZB1) promotes gut IgA secretion and its absence results in pronounced dextran sulfate sodium salt (DSS)-induced colitis. In the present study, we explored the role of MZB1 in CRC development using the azoxymethane (AOM)/DSS-induced CRC model. We observed an increase in both the number and size of the tumor nodules in Mzb1-/- mice compared with Mzb1+/+ mice. The increase in CRC development and progression in Mzb1-/- mice was associated with reduced intestinal IgA levels, altered gut flora, and more severe gut and systemic inflammation. Oral administration of the monoclonal IgA, W27, alleviated both the gut inflammation and AOM/DSS-induced CRC. Notably, cohousing Mzb1+/+ and Mzb1-/- mice from the 10th day after birth led to similar CRC development. Our findings underscore the pivotal role of MZB1-mediated IgA secretion in suppressing the onset and progression of CRC triggered by gut inflammation. Moreover, our study highlights the profound impact of microbiota composition, modulated by gut IgA levels, on gut inflammation. Nonetheless, establishing a direct correlation between the severity of colitis and subsequent CRC development and the presence or absence of a particular microbiota is challenging.

Twitterati on COVID-19 pandemic-environment linkage: Insights from mining one year of tweets.

The COVID-19 pandemic seems to have had positive (although short-lived, e.g., reduction in pollution due to lockdown) as well as negative (e.g., increasing plastic pollution due to use of disposable masks, etc.) impacts on the environment. The pandemic-environment linkage also includes circumstances when regions experienced extreme weather events, such as floods and cyclones, and disaster management became challenging. This study aims to examine the trends in public discourses on Twitter on these interactions between the pandemic and environment. The present study follows the most recent literature on understanding public perceptions - which acknowledges Twitter to be an abundant source of information on public discussions on any global issue, including the pandemic. A Python-based code is developed to extract Twitter data spanning over a year, and analyze the presence of covid-environment related keywords and other attributes. It is found that the Twitterati aggressively viewed the impacts (such as economic slowdown and high mortality) of the pandemic as miniatures of the results of future climate change. The community was also highly concerned about the varying air and plastic pollution levels with the change in lockdown and covid prevention policies. Extreme weather events were a high-frequency topic when they impacted countries such as India, the USA, Australia, the Philippines and Vietnam. This study makes a novel attempt to provide an overview of public discourses on the pandemic-environment linkage and; can be a crucial addition to the literature on assessing public perception of environmental threats through Twitter data mining.

Two-step approach based multi-objective groundwater remediation using enhanced random vector functional link integrated with evolutionary marine predator algorithm.

We here propose a two-step approach-based simulation-optimization model for multi-objective groundwater remediation using enhanced random vector functional link (ERVFL) and evolutionary marine predator algorithm (EMPA). In this study, groundwater flow and solute transport models are developed using MODFLOW and MT3DMS. The ERVFL network is used to approximate the flow and transport models, enhancing the computational performance. This study also improves the robustness of the ERVFL network using a kernel density estimator (KDE) based weighted least square approach. We further develop the EMPA by modifying the marine predator algorithm (MPA) using elite opposition-based learning, biological evolution operators, and elimination mechanisms. In the multi-objective version of EMPA, the non-dominated/Pareto-optimal solutions are stored in an external repository using an archive controller and adaptive grid mechanism to promote better convergence and diversity of the Pareto front. The proposed methodologies are applied for multi-objective groundwater remediation of a hypothetical unconfined aquifer based on the two-step method. The first step directly integrates flow and transport models with EMPA and finds the optimal locations of pumping wells by minimizing the percent of contaminant mass remaining in the aquifer. In the second step, the ERVL-based proxy model is integrated with EMPA and used for multi-objective optimization while explicitly using the pumping well locations obtained in the first step. The multi-objective optimization generates a Pareto-optimal solution representing the relationship between the rate of pumping and the amount of contaminant mass in the aquifer. Further analyses show a significant advantage of the two-step approach over a traditional method for multi-objective groundwater remediation.

Two dimensional NbSe2/Nb2O5 metal-semiconductor heterostructure-based photoelectrochemical photodetector with fast response and high flexibility.

Two dimensional (2D) metal-semiconductor heterostructures are promising for high-performance optoelectronic devices due to fast carrier separation and transportation. Considering the superior metallic characteristics accompanied by high electrical conductivity in NbSe2, surface oxidation provides a facile way to form NbSe2/Nb2O5 metal-semiconductor heterostructures. Herein, size-dependent NbSe2/Nb2O5 nanosheets were achieved by a liquid phase exfoliation method and a gradient centrifugation strategy. These NbSe2/Nb2O5 heterostructure-based photodetectors show high responsivity with 23.21 µA W-1, fast response time of millisecond magnitude, and wide band detection ability in the UV-Vis region. It is noticeable that the photocurrent density is sensitive to the surface oxygen layer due to the oxygen-sensitized photoconduction mechanism. The flexible testing of the NbSe2/Nb2O5 heterostructure-based PEC-type photodetectors exhibits high photodetection performance even after bending and twisting. Beyond that, the solid-state PEC-type NbSe2/Nb2O5 photodetector also achieves relatively stable photodetection and high stability. This work promotes the application of 2D NbSe2/Nb2O5 metal-semiconductor heterostructures in flexible optoelectronic devices.

Dynamics of upstream saltwater intrusion driven by tidal river in coastal aquifers.

For the coastal aquifers, recent research have shown that the tidal has a significant effect on saltwater intrusion in the near-shore aquifer. However, it is currently unclear how the tidal river contributes to the groundwater flow and salinity distribution in the upstream aquifer of the estuary. This study examined the effects of a tidal river on the dynamic characteristics of groundwater flow and salt transport in a tidal river-coastal aquifer system using field monitoring data and numerical simulations. It was found that changes in tidal-river level led to the reversal of groundwater flow. For a tidal cycle, the maximum area of seawater intrusion is about 41.16 km2 at the end of the high tide stage. Then the area gradually decreased to 39.02 km2 at the end of the low tide stage. More than 2 km2 area variation can be observed in a tidal cycle. Compared to the low tide stage, the area of SWI increased by 5 % at high tide stage. The SWI region was also spreading landward from the tidal river. In addition, we quantified the water exchange and salt flux between the tidal river and aquifer. When the tidal fell below the level of the riverbed, the water exchange rate was stabilized at about -1.6 m/h. The negative value indicated that the river was recharged by the groundwater. With the increasing of tidal water level, the water exchange rate gradually changes from negative to positive and reached the maximum value of 3.2 m/h at the beginning of the falling tide stage. The presence of a physical river dam can amplify the difference in water level between high and low tides, thereby enhancing the influence of a tidal river on water exchange and salt flux. The findings lay the foundation for gaining a comprehensive understanding of the tidal river on groundwater flow and salt transport in upstream aquifers.