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Based on the principle of dynamic programming model, this paper studies the market transaction problem and establishes a transaction model to help decision-making. First, on the basis of the historical price data of gold and bitcoin, the data is processed by the wavelet transform method to ensure the accuracy of the model. Second, a time-series forecasting model and a back-propagation neural network are employed to predict the future prices of gold and bitcoin. And use a dynamic programming model to recursively determine the specific investment ratio of each asset in each transaction to achieve the best return. Finally, the effect of the model is verified by the evaluation index and transaction cost sensitivity test. The results show that transaction costs affect both strategy and outcomes. As transaction costs increase, both transaction frequency and total assets show a downward trend.

Mass independent fractionation (MIF) of even mercury (Hg) isotopes has long been observed in atmospheric related samples and is confirmed to be generated in the atmosphere, but its exact mechanism is covered up by the Hg sources and atmospheric transformations and stays unclear. Here, we present the first Hg isotope compositions of particulate bound mercury (PBM) in the Northwest Pacific and observe highly positive Δ200Hg values (up to 0.42 ‰). The MIF signatures are mainly controlled by photoreduction, gaseous elemental mercury (GEM) oxidation, and even-MIF dominated oxidation processes. Mercury in a small part of samples influenced by anthropogenic emissions is recognized by Hg concentrations and Δ199Hg signatures. The correlation between Δ200Hg and light conditions confirms that even-MIF is linked to photochemical reactions. The correlation between Δ200Hg and altitudes suggests that a max even-MIF signatures existed in the troposphere. We use Δ199Hg/Δ200Hg ratios and ternary isotopic mixing model to estimate the contributions of photoreduction, GEM oxidation and even-MIF dominated oxidation. Our results demonstrate that atmospheric transformations are far more important than Hg sources in shifting Hg isotope compositions of PBM samples, especially in the marine boundary layer of the open ocean, which is characterized by less anthropogenic influences and has implications for our understanding of the mechanism of even-MIF and subsequently Hg behaviors in the atmosphere.

A simple resorcinol method to determine nitrate (NO

As one of the most productive marine ecosystems in the tropics and subtropics, mangroves are an important part of the global mercury (Hg) cycling. The environmental processes and effects of Hg in mangroves are complex and affect human Hg exposure, and it is crucial to understand Hg behaviors in the mangrove ecosystem. However, clarifying Hg behaviors in the mangrove ecosystem remains difficult because of an insufficient understanding of the dominant pathways. In this study, measurements of mercury (Hg) concentration and isotope ratios in sediment and plant tissues from a mangrove wetland were used to investigate Hg isotope fractionation in mangrove plants and sediments. Spatial patterns in Hg concentration and isotope signatures indicate that Hg re-emission in the sediment was suppressed by mangrove plants. The ratio of Δ199Hg/Δ201Hg was 0.93 for all sediments, indicating that Hg mass-independent fractionation in the mangrove ecosystem was primarily affected by photoreduction, while the ratios of Δ199Hg/Δ201Hg and Δ199Hg/δ202Hg for plant tissues suggested that natural organic matter reduction of Hg(II) was occurred in the plants. The distinct positive Δ199Hg values found in mangrove plants were supposed to be the results of the unique physiological characteristics of mangroves. The exterior Hg sources from atmosphere and seawater emphasize the role of mangrove ecosystems in the global Hg biogeochemistry. Our study highlights the distinct Hg isotope signatures in the mangrove from that in forests and indicates unique Hg behaviors in the mangrove ecosystem.

Marine debris characterization is fundamental for developing policies aiming at ending the flow of marine debris at the source. China has the largest coastal population in the world. For this emerging economy, the sources of debris might be different from those in regions at different developmental stages. As a typical coastal tourist city and a special economic zone in East China, there are multiple sources of marine debris continuously produced around Xiamen. Marine debris characterization here could provide insights into regulatory measures. Therefore, the abundance and composition of marine debris around Xiamen were investigated. Average densities of floating, beached, benthic macro-debris and floating microplastics (0.5 mm - 5 mm) were 3963 ± 2027 items km−2, 0.13 ± 0.08 items m−2, 20,274 ± 15,873 items km−2 and 36,455 ± 33,935 items km−2, respectively. Based on the Clean Coast Indexes, the beaches investigated were supposed to be “very clean” most of the time (73.2% ± 34.9%). Wastes with low value for recycling/reuse, such as grocery bags, ropes, and foams, were the main items of marine debris in the study area. Both domestic sources from the upstream and local fishing/aquaculture activities significantly contributed to marine debris. Obvious regional differences in benthic debris categories could be explained by both natural factors and the rural-urban gap in economic levels, waste-management strategies and infrastructure. These might be common features in this emerging market and densely populated economy. The findings provide insights into the sources of mismanaged waste around this tourist city and some neglected deficiencies in China's current solid waste management system.

An isotope binary mixing model was applied for high precision measurement of mercury isotope ratios in samples with low mercury concentrations by multicollector inductively coupled plasma mass spectrometry (MC-ICPMS). Standard addition was used to evaluate the precision and accuracy of the isotope composition calculations resulting from the isotope binary mixing model. A high, steady 202Hg signal of approximately 2.13 V was achieved, with the mercury concentration reaching 3 ng/mL. The isotopic composition of three standards (NIST SRM 1646a; NIST SRM 1575a; BCR 482) and natural samples were precisely determined. The standards and natural samples were diluted to low mercury concentrations (low to 0.90 ng/mL) and mixed with standard solutions (NIST SRM 3133) with high mercury concentrations (50 ng/mL); the isotopic compositions of low mercury concentration samples were calculated using an isotope binary mixing model after the isotopic compositions of the mixing solutions were measured. The results showed that the uncertainty of the calculated mercury isotopic compositions was in an acceptable range and the calculation isotope data were in good agreement with direct measurements. Our method allows the precise determination of mercury isotope composition in mercury solutions of concentrations (0.90 ng/mL) below the detection limit of the current system (3.00 ng/mL).

Long non-coding RNAs are associated with cancer progression. Long intergenic non-protein coding RNA (linc)-regulator of reprogramming (ROR) enhances tumor development in hepatocellular carcinoma (HCC). However, the effect of chemoresistance and its underlying mechanisms in HCC are not completely understood. The present study aimed to identify the effect of ROR on sensitivity to doxorubicin (DOX) in HCC cells. In the present study, Cell Counting Kit-8 and EdU assays were performed to assess cell viability and proliferation, respectively. In addition, E-cadherin and vimentin protein expression levels were assessed via western blotting and immunofluorescence. The results of the present study demonstrated that HCC cells with high linc-ROR expression levels were more resistant to DOX, and linc-ROR knockdown increased HCC cell DOX sensitivity compared with the control group. The results indicated that compared with the NC siRNA group, linc-ROR knockdown notably suppressed epithelial-mesenchymal transition by downregulating twist family bHLH transcription factor 1 (TWIST1) expression. TWIST1 knockdown displayed a similar effect on HCC cell DOX sensitivity to linc-ROR knockdown. Moreover, linc-ROR knockdown-induced HCC cell DOX sensitivity was inhibited by TWIST1 overexpression. The present study provided evidence that linc-ROR promoted HCC resistance to DOX by inducing EMT via interacting with TWIST1. Therefore, linc-ROR might serve as a therapeutic target for reducing DOX resistance in HCC.

Pharmaceuticals and personal care products (PPCPs) in the sea area surrounding a densely populated tourist city in southeastern China were investigated. In total, 32 PPCP pollutants classified into 23 categories were detected. Different spatial distribution patterns of PPCPs indicated possible contamination from runoff and multiple local sources. The labile-to-conservative ratios of PPCPs showed the influence of untreated domestic sewage. In addition, increased concentrations of ciprofloxacin, enrofloxacin, and erythromycin around aquaculture farms imply that aquaculture cannot be neglected as a source. The concentrations of oxytetracycline, ranitidine, ciprofloxacin, miconazole, and sulfamethizole were higher in the wet season than those in the dry season, and the difference in pharmaceutical consumption was suspected to be the main driving factor of this seasonal variation. The risk quotients calculated with the maximum concentrations of miconazole, triclosan, dehydronifedipine, and triclocarban exceeded 0.1, indicating potential moderate or high risks. Antibacterial agents in daily chemicals and azole broad-spectrum antifungals were associated with the highest risks in this study; this might be another significant pollution characteristic in the sea area around this subtropical tourist city. Supplementary Information The online version contains supplementary material available at 10.1007/s11356-020-12335-1.

The safety and feasibility of laparoscopic versus open liver resection (LLR vs. OLR) associated lymphadenectomy for intrahepatic cholangiocarcinoma (ICC) are still controversial. The aim of the present study was to compare short and long-term outcomes. We reviewed data on 43 consecutive patients who underwent curative liver resection with associated lymphadenectomy for ICC. The short-term outcomes including postoperative morbidity and mortality, and the long-term outcomes including overall survival (OS) and recurrence-free survival (RFS) were compared. The median survival, 1- and 3-year OS in LLR and OLR groups were 22.5 months, 76.9% and 47.1%, and 12.1 months, 43.1% and 20.0%, respectively. The median survival, 1- and 3-year RFS in LLR and OLR groups were 10.3 months, 27.8% and 0%, and 8.1 months, 24.0% and 4.0%, respectively. The results showed that LLR obviously reduced intraoperative blood loss (median, 375 vs. 500ml, p = 0.016) and postoperative hospital stay (median, 6 vs. 9 days, p = 0.016). Moreover, there was no significant difference in short-term outcomes including postoperative morbidity (including wound infection, bile leakage, liver failure and pneumonia) and mortality within 30 days, and long-term outcomes including OS and RFS between LLR and OLR. (all p > 0.05). Multivariate analysis showed that CA19-9 level, TNM stage, and tumor differentiation were independent risk factors for OS and RFS. LLR for ICC is safety and feasibility compared with OLR. The advantage of LLR was to reduce intraoperative blood loss and postoperative hospital stay.

Real-time determination of nitrate (NO3−) concentration is critical for scientific research and water quality monitoring. However, few methods have been reported for underway determination of NO3− concentration in seawater. In this study, a reverse flow injection system coupled with a custom-made linear light path flow cell and vanadium reduction was developed for the spectrophotometric determination of NO3− in seawater. Sulfamic acid was used to remove the initial NO2− content in samples prior to NO3− reduction. A custom-made linear light path flow cell was constructed using simple components. The reagent concentration was optimized and the effects of organic nitrogen and salinity on NO3− determination were investigated. Method detection limits were 0.02 µM and 0.03 µM for freshwater and seawater, while the working range reached a maximum of 6 µM and 7.5 µM, respectively. The upper limits of the working range could be extended by using a shorter flow cell or applying a lower reaction temperature. The recoveries varied from 88.0% to 106.0% for spiked samples with different matrices. The analytical results obtained using the proposed method were found to exhibit good correlation with the results generated using two reference methods. Furthermore, the proposed method was successfully applied to the underway analysis of NO3− concentration in the Jiulong River estuary and Xiamen coastal seawater (Fujian, China). Overall, these results indicate that the newly developed method has high potential for use in environmental monitoring.

Resistance to chemotherapy drugs remains a significant problem for the treatment of many types of cancer. Fascin‑1 (FSCN‑1) is an actin-bundling protein involved in the invasion and metastasis of a variety of tumors. However, its involvement in drug resistance in hepatocellular carcinoma (HCC) remains unclear. The present study aimed to investigate the function of FSCN‑1 in HCC resistance to doxorubicin (DOX). FSCN‑1 expression was increased in DOX-resistant HCC cell lines (SNU449 and SNU387) compared with DOX-sensitive cell lines (Huh7 and Hep3B). The resistance of HCC cells to DOX was decreased following FSCN‑1 knockdown with small interfering RNA. FSCN‑1 knockdown also significantly altered the expression of key markers of epithelial-mesenchymal transition (EMT). Notably, vimentin expression was reduced and epithelial‑cadherin expression was increased. Furthermore, when EMT was suppressed through knockdown of Twist, an essential pathway of DOX-induced EMT, the viability of HCC cells following treatment with DOX was not affected by FSCN‑1 expression. Furthermore, FSCN‑1 knockdown eliminated hypoxia-induced doxorubicin resistance and EMT. The results of the present study indicated that FSCN‑1 expression increased DOX resistance in HCC cells via the promotion of EMT, and this phenomenon was maintained in a hypoxic environment. FSCN‑1 potentially represents a novel target to overcome resistance to DOX in HCC.

Isotope signatures of mercury (Hg) were determined for Hg fractions in seawater, sediments, porewaters, core sediments and fish from the Yundang Lagoon, Xiamen, China. Sequential extraction was used to extract Hg fractions in sediments and the purge-trap method was used to preconcentrate Hg in seawater. A large variation in mass dependent fractionation (δ202Hg: −2.50‰ to −0.36‰) was observed in the lagoon. Seawater and fish samples showed positive mass-independent fractionation (Δ199Hg: −0.06‰–0.45‰), while most of sediment and porewater samples displayed insignificant mass-independent fractionation (Δ199Hg: −0.10‰–0.07‰). Ancillary parameters (total organic carbon, sulfide, pH, Eh, water content and grain size) were also measured in the sediments to investigate correlations with Hg isotopes. Three sources (domestic sewage, sediments and atmospheric deposition) were identified as the main sources of Hg in the lagoon seawater. Photochemical reaction was the main process causing isotope fractionation in seawater. Through Hg partitioning and deposition, light isotopes were enriched from dissolved Hg to particulate Hg, then to sediments, and then to porewaters. Finally, Hg isotope signatures were used to identify the Hg sources and fractionation processes in core sediments from different depths. Our results demonstrate that Hg isotopes are powerful tools for tracing Hg sources and arriving at a better understanding of Hg biogeochemical cycling in the lagoon after long-term interventions.

By making use of the critical point theory, we establish some new existence criteria to guarantee that a 2nth-order nonlinear difference equation containing both advance and retardation with p-Laplacian has a nontrivial homoclinic orbit. Our conditions on the potential are rather relaxed, and some existing results in the literature are improved.

Microplastic pollution is widespread across most ocean basins around the world. Microplastics (MPs) are small plastic particles that have a significant impact on the marine environment. Various research on plastic pollution have been conducted in several regions. However, currently, there is limited data on the distribution and concentration of MPs in the mid-west Pacific Ocean. Therefore, this study we investigated the abundance, distribution, characteristics, and compositions of MPs in this region. Sea surface water samples collected from 18 stations showed a microplastic concentration range of 6028–95,335 pieces/km2 and a mean concentration of 34,039 ± 25,101 pieces/km2. Highest microplastic concentrations were observed in the seamount region of western Pacific. We observed a significant positive correlation between microplastic abundance and latitude across the study region. It was observed that microplastic concentrations decreased with increasing offshore distance at sites located on a 154° W transect. Fibres/filaments were the dominant microparticles observed in this study (57.4%), followed by fragments (18.3%). The dominant particle size range was 1–2.5 mm (35.1%), followed by 0.5–1 mm (28.5%), and the dominant particle colour was white (33.8%), followed by transparent (31.0%) and green (24.6%). The most common polymer identified by μ-Raman was polypropylene (39.1%), followed by polymethyl methacrylate (16.2%), polyethylene (14.1%) and polyethylene terephthalate (14.2%). The possible sources and pathways of microplastics in the study area were proposed based on the morphological and compositional characteristics of particles, their spatial distribution patterns, and shipboard current profiling (ADCP). Our study contributes to the further understanding of MPs in remote ocean areas.

Taxi is one of the important connections between large transportation hubs and urban transportation. This paper addresses the decision-making strategy for airport taxi drivers in order to improve transportation efficiency. Firstly, the decision-making model of taxi drivers based on opportunity cost is established. This paper also takes Beijing Capital International Airport as an example to solve this model by combining the queuing theory and Monte Carlo method, and uses the Logit model to analyze the correlative factors. Then, the suggestion of setting up the taxi pick-up points is proposed to improve the efficiency of traffic flow. Finally, result of computer simulation further shows that when the entrance of the fast lane is about 11 parking spaces away from the taxi pick-up point, it can improve the efficiency of traffic flow and lead to a tripartite win-win situation: taxi drivers get higher revenue, passengers leave the airport in time and the managers to execute the airport more efficiently.

China is the largest plastic consumer in the world. Despite its plastic waste import ban in 2017, this populous economy inevitably generates a large amount of waste, including plastic waste, a considerable part of which has become marine litter. Data from the 2018 National Coastal Cleanup and Monitoring Project, the largest beach litter monitoring activities using the citizen science approach in China, have been retrieved and analyzed to understand spatial patterns, composition, and original usage of marine litter. Within this project, 24 beaches were surveyed every two months. As a result, the mean density was 3.85 ± 5.39 items m−2, much higher than that reported by previous studies in China. There were great differences in the spatial distribution of litter. The highest densities appeared in the runoff-affected area of the Yangtze River, which was another difference from previous studies. Low-density, easy-to-transport foamed plastics were the major contributor to marine litter in these areas. Along China's coast, approximately 90% of litter was from land-based sources, and over half of that originated from domestic sources. Including foamed plastic products, plastic litter with low recycling value dominated. Both natural and human factors influencing the spatiotemporal distribution and composition of litter are discussed. Socioeconomic factors, such as the lifestyle and consumption levels of citizens and local waste management systems, are possible explanations for the low-value characteristic of marine litter. The deviation between previous data and citizen science data in this study may be caused by many factors. Based on the discussion on these factors, some suggestions for citizen science research in China are also put forward.

People are increasingly aware of ubiquitous microplastic (MP) pollution in the world's ocean due to its far-reaching harmful impacts on marine ecosystem and potential hazards to human health, yet surprisingly comparatively limited studies about the abundance, source, transport, and fate of MPs in the Northwestern Pacific Ocean are available. We conducted the field survey of MPs pollution at the surface of the Northwestern Pacific Ocean between August 25 and September 26, 2017. MPs were collected from 18 sampling stations in the Northwestern Pacific Ocean using a manta trawl net with a mesh size of ∼330 μm and a rectangular net opening of 0.45 × 1 m. The abundance, shape, color, size, chemical composition, and surface morphology were characterized using light microscopy, μ-Raman spectroscopy, and scanning electron microscopy (SEM). The results show surface MPs at concentrations ranging over two orders of magnitude (6.4 × 102 to 4.2 × 104 particles km−2) and a mean abundance of 1.0 × 104 particles km−2. The most concentrated MPs were found at XTJ3-9, which may be associated with the convergence of surface currents collectively affected by the Kuroshio and its extension, adjacent eddies, and flow regimes. Polyethylene accounts for 57.8% of enumerated MPs, followed by polypropylene (36.0%) and nylon (3.4%). Pellets, sheets, lines, and films are major forms which may be linked to the breakdown of larger particles, aging processes, and movement over long distances by prevailing currents. Four possible MPs migration pathways were proposed based on the source-specific distribution, chemical fingerprints, size distribution patterns, and the observed physical oceanographic parameters.

Objective: To investigate the application of proximal splenic vein (SV) ligation in laparoscopic splenectomy plus pericardial devascularization (LSPD) surgery. Methods: From January 2017 to December 2018, 31 patients with portal hypertension of liver cirrhosis in Zhejiang Provincial people’s Hospital were treated with LSPD surgery with the ligation of proximal SV. Results: All the 31 patients were performed without any transfer to open operation. The operation time were 139.35 ± 19.48 min, blood loss were 138.06 ± 54.49 ml. Postoperative hospital stay (PHS) was 8.26 ± 1.59 days. There were 4 patients with postoperative portal vein thrombosis (PVT), among them 2 patients were degree I and 2 patients were degree II. There are no severe postoperative PVT cases. There were no abdominal infection, no pancreatic leakage, no abdominal hemorrhage, no liver failure or no upper gastrointestinal bleeding cases. Conclusion: LSPD combined with ligation of proximal SV is safe and feasible, and short-term follow-up can effectively prevent the formation of PVT after operation.

Herein, a flow injection analysis (FIA) was established for the spectrophotometric determination of total dissolved nitrogen (TDN) in natural waters. An on-line ultraviolet digester was used for sample digestion, and a nontoxic and soluble reductant, vanadium chloride (VCl3), was for the first time used in flow injection method for TDN determination. The digestion mode, reagent concentration, and influence of organic matter were investigated. The experimental results revealed a detection limit of 0.04 mgN L−1 and linearity of up to 3.0 mgN L−1. Recovery from natural water samples was between 87.0 and 104.4%. The accuracy of the method was ensured by using national certified reference materials of total nitrogen GSB 07-3168-2014 (batch NO. 203261 and 203262), and satisfactory results were achieved. The proposed method was used to the determination of TDN in natural water samples, and results obtained were similar to those provided by the autoclave alkaline persulfate digestion and copperized cadmium column reduction method. The results obtained herein showed that the proposed method had a high potential for field or monitoring application.

Coastal upwelling that brings to the surface both CO2- and nutrient-rich deep seawater is related to acidification and intense biological productivities in surface waters. However, the impact of biological activities on upwelling-induced acidification from nearshore to offshore areas in an upwelling zone remains insufficiently known. In this paper, we present daily records of high-resolution profiles of carbonate chemistry and hydrographic parameters from the nearshore to the offshore upwelling zone off the east coast of Hainan Island (ECH) in July 2014 (summer season). A three end-member mixing model was adopted to discriminate biological processes from physical mixing and to further semiquantitatively diagnose biological contribution to the upwelling-induced acidification. The results show divergent responses in pH, aragonite saturation state (ΩAr) and biomediated nonconservative dissolved inorganic carbon (ΔDIC) at depths of 10 m–30 m between nearshore and offshore regimes under the on-going coastal upwelling, which were attributed to the distinct roles of biological activities in mediating acidification in the upper 30 m across the ECH. Specifically, in the offshore regime, enhanced photosynthesis reduced the upwelling-induced acidification by 40% (i.e., type C: relief role), whereas aerobic respiration increased acidification in the subsurface waters of the nearshore regime by 15% (i.e., type B: aggravation role). This led to the pH and ΩAr minimum in upwelled waters along the transect from the nearshore to the offshore. In contrast, the biological contribution was almost negligible over surface waters in the nearshore regime because of the balance between net community productivity and net community calcification (i.e., type A: limited or minor role).

We investigate the discrete nonlinear Schrodinger equations with indefinite sign subquadratic potentials. Making use of the critical point theory, we obtain a new result concerning the existence of a standing wave solution.

By making use of the critical point theory, the existence of periodic solutions for fourth-order nonlinear p-Laplacian difference equations is obtained. The main approach used in our paper is a variational technique and the Saddle Point Theorem. The problem is to solve the existence of periodic solutions of fourth-order nonlinear p-Laplacian difference equations. The results obtained successfully generalize and complement the existing one.

Using the critical point method, the existence of periodic solutions for second-order nonlinear difference equations containing both advance and retardation is established. The proof is based on the Saddle Point Theorem in combination with variational technique.

The discrete non-linear Schrödinger equation is one of the most important inherently discrete models, having a crucial role in the modelling of a great variety of phenomena, ranging from solid-state and condensed-matter physics to biology. In this paper, a class of discrete non-linear Schrödinger equations are considered. Using critical point theory in combination with periodic approximations, we establish some new sufficient conditions on the existence results for solitons of the equation. The classical Ambrosetti–Rabinowitz superlinear condition is improved.

By using the critical point method, some new criteria are obtained for the existence and multiplicity of homoclinic solutions to a 2nth-order nonlinear difference equation. The proof is based on the Mountain Pass Lemma in combination with periodic approximations. Our results extend and improve some known ones.

In this paper, we obtain a new sufficient condition on the existence of breathers for the discrete nonlinear Schrodinger equations by using critical point theory in combination with periodic approximations. The classical Ambrosetti–Rabinowitz superlinear condition is improved.

A reverse flow injection method was established for simultaneous spectrophotometric determination of NO2− and NO3− in seawater. Vanadium chloride, a nontoxic and soluble reductant, was used to replace highly toxic cadmium for the reduction of NO3− to NO2−. Sulfamic acid was used in the automated spectrophotometric method, to remove NO2− interference before NO3− reduction was performed. The concentrations of NO2− and NO3− were directly quantified using their respective calibration curves. The experimental parameters for both NO2− and NO3− determination were optimized with a univariate experimental design process. The salinity effect was investigated, indicating that measurement correction was not necessary. Method detection limits of the proposed method for NO2− and NO3− detection were 0.09 µM and 0.18 µM, with linearity up to 12 µM and 70 µM, respectively. Recovery from seawater samples varied from 95.0% to 105.0% for NO2− and 95.0% to 104.3% for NO3−. The relative standard deviations of spiked samples with different concentrations were all below 1.2% (n = 7). The accuracy of the method was validated by comparison with the copper-coated cadmium column reduction method, showing that the results were satisfactory. The proposed method was then successfully applied to NO2− and NO3− concentration determination in seawater samples. The proposed method exhibited no significant interference from salinity, with easier operation and calculation methods, making it highly suitable for routine analysis and potentially for underway monitoring.

High-resolution satellite observations of sea surface temperature (SST) were used to derive the daily SST fronts and monthly frontal probability (FP) in the South China Sea (SCS). A gradient-based frontal detection method was applied to increase the accuracy for frontal identification. The current study offered a comprehensive description for the variability of SST front and the associated dynamics in the SCS. Large variability was found along the coast of China and Vietnam, northwest of Luzon Island, and the corresponding seasonal cycle captured highest (lowest) values in winter (fall). The wind pattern was found highly influential for frontogenesis. The northeast monsoon in winter drove onshore Ekman transport near the coast of China, which induced convergence between coastal cold water and onshore warm water. The southwest monsoon during summer induced offshore transport, which brought upwelling near the coast of southeast Vietnam and east of Hainan Island. There were fronts generated between cold coastal water and offshore warm water during both monsoon patterns for impacted regions. The integrated effect from intrusion of the Kuroshio Current, wind stress curl and eddy activity were found favorable for generating fronts near Luzon Island. The dynamical relationship was more prominent at anomalous field that higher FP was associated with larger wind stress. And the interannual variability of fronts in the basin was clearly impacted by El Nino related large-scale atmospheric signals.

As a measure of the sustainability of a country, a state’s fragility is attributed to numerous elements. Meanwhile, climate change is a potential global threat in the 21st century, which may further aggravate the fragility of countries. Concerning this issue, we propose an index system, the Fragile States Metric System (FSMS) to measure state fragility, which includes five dimensions: climate change, cohesion, economy, politics and society. Our FSMS consists of the Climate Change Metric System (CCMS) and Modified Conflict Assessment System (M-CAS). While establishing the model, we introduce a new hybrid evaluation method, Gray Relational Analysis (GRA)-Entropy method and variable weight function model, to calculate the weights. As the result, from 2007 to 2017, European countries, in particular Finland, Norway, Switzerland, Sweden and Denmark, remained the top 5 most stable countries. Robustness analysis proves that FSMS is a relatively stable model. In addition, in the application of FSMS, we introduce the economic theory, Pareto Optimum, to measure intervention costs while mitigating state fragility.

In the fourth Chinese National Arctic Research Expedition (from July to September, 2010), 14 surface sediment samples were collected from the Bering Sea, Chukchi Sea, and Canadian Basin to examine the spatial distributions, potential sources, as well as ecological and health risk assessment of polycyclic aromatic hydrocarbons (PAHs). The ∑PAH (refers to the sum of 16 priority PAHs) concentration range from 27.66 ng/g to 167.48 ng/g (dry weight, d.w.). Additionally, the concentrations of ∑PAH were highest in the margin edges of the Canadian Basin, which may originate from coal combustion with an accumulation of Canadian point sources and river runoff due to the surface ocean currents. The lowest levels occurred in the northern of Canadian Basin, and the levels of ∑PAH in the Chukchi Sea were slightly higher than those in the Being Sea. Three isomer ratios of PAHs (Phenanthrene/Anthracene, BaA/(BaA+Chy), and LMW/HMW) were used to investigate the potential sources of PAHs, which showed the main source of combustion combined with weaker petroleum contribution. Compared with four sediment quality guidelines, the concentrations of PAH are much lower, indicating a low potential ecological risk. All TEQPAH also showed a low risk to human health. Our study revealed the important role of the ocean current on the redistribution of PAHs in the Arctic.

Prevalence of microplastics (MPs) throughout the world's oceans has raised growing concerns due to its detrimental effects on the environment and living organisms. Most recent studies of MPs, however, have focused on the estuaries and coastal regions. There is a lack of study of MPs pollution in the open ocean. In the present study, we conducted field observations to investigate the abundance, spatial distribution, and characteristics (composite, size, color, shape and surface morphology) of MPs at the surface of the Northwestern Pacific Ocean. Samples of MPs were collected at 18 field stations in the Northwestern Pacific Ocean using a surface manta trawl with a mesh size of ~330 μm and width of 1 m from August 25 to September 26, 2017. The MPs were characterized using light microscopy, Micro-Raman spectroscopy, and scanning electron microscopy (SEM). Our field survey results indicate the ubiquity of MPs at all stations with an abundance from 6.4 × 102 items km−2 to 4.2 × 104 items km−2 and an average abundance of 1.0 × 104 items km−2. The Micro-Raman spectroscopic analysis of the MPs samples collected during our field survey indicates that the dominant MPs is polyethylene (57.8%), followed by polypropylene (36.0%) and nylon (3.4%). The individual chemical compositions of MPs from the stations within the latitude range 123–146°E are comparable with each other, with PE being the dominating composition. Similar chemical fingerprints were observed at these field stations, suggesting that the MPs originated from similar sources. In contrast, the major MPs at the field stations adjacent to Japan is polypropylene, which may originate from the nearby land along the coast of Japan. Physical oceanography parameters were also collected at these stations. The spatial distribution of MPs is largely attributed to the combined effects of flow pattern, adjacent ocean circulation eddies, the Kuroshio and Kuroshio Extension system.

In this paper, we investigate the solutions of boundary value problems for second-order p-Laplacian difference equations. By using the critical point theory, the existence and multiple results are obtained.

In this paper, a fourth-order nonlinear p-Laplacian difference equation is considered. Using the critical point theory, we establish various sets of sufficient conditions of the nonexistence and existence of solutions for Neumann boundary value problem and give some new results. The existing results are generalized and significantly complemented.

Our research was conducted to analyze the outcomes of two laparoscopic splenectomy plus pericardial devascularization (LSPD) techniques in the management of portal hypertension (PTH) and hypersplenism. Between May 2012 and May 2013, 41 patients with PTH and hypersplenism undergoing LSPD were retrospectively analyzed. Of them, 29 patients received LSPD by LigaSure™ Vessel Sealing System (LVSS) and Endo-GIA™ universal endoscopic vascular linear staplers (Endo-GIA) (EG Group) and 12 patients received LSPD by LVSS and Hem-o-Lock (HL Group). Operating time, intraoperative blood loss, postoperative course, and hospitalization costs were compared between the two LSPD combination techniques. There were no significant differences in preoperative patient characteristics of the two groups. Significantly less operating time, intraoperative blood loss, and postoperative complications were observed in EG Group. The incidence of portal vein thrombosis was lower in the EG Group (3.4 vs. 8.3 %), as well as the incidence of pancreatic fistula (0 vs. 8.3 %). Upper gastrointestinal hemorrhage was not observed in either group. Uncontrolled bleeding warranted conversion to open surgery in one case in EG Group (conversion rate 3.4 %) and in two cases in HL Group (conversion rate 16.7 %). Two patients (16.7 %) in HL Group underwent successful emergency exploratory laparotomy due to uncontrolled intraabdominal bleeding postoperatively. No re-operation was needed in EG Group. Two patients experienced liver failure after surgery in each group. Of those, three patients were managed successfully and one patient refused further therapy. While the overall complication rate was significantly lower in EG Group (17.2 vs. 58.3 %, P

Using the critical point theory, we obtain the existence of a nontrivial homoclinic orbit for second order \(p\)-Laplacian difference equations containing both advance and retardation. The proof is based on the Mountain Pass Lemma in combination with periodic approximations. One of our results generalizes and improves the results in the literature.