Search

Carbapenem-resistant Klebsiella pneumoniae (CRKP) has emerged as a severe threat globally and is associated with increased lengths of hospital stay and high mortality in affected patients. The spread of CRKP is largely driven by a few dominant lineages, including ST11-KL64, the dominant type in China with a worldwide distribution.

In this study, we investigate mechanisms that generate regularly-spaced, iron banding in upland soils. These redoximorphic features appear in soils worldwide, but their genesis has been heretofore unresolved. Upland soils are highly redox dynamic, with significant redox fluctuations driven by rainfall, groundwater changes, or irrigation. Pattern formation in these highly dynamic systems provides an opportunity to investigate the temporal dimension of spatial self-organization, which is not often explored. By comparing multiple alternative mechanisms, we find that regular redox patterns in upland soils are formed by coupling two sets of scale-dependent feedbacks (SDF), the general framework underlying Turing instability. The first set of SDF is based on clay aggregation and disaggregation. The second set is realized by threshold-dependent, negative root responses to aggregated crystalline Fe(III). The former SDF amplifies Fe(III) aggregation and crystallinity to trigger the latter SDF. Neither set of SDF alone is sufficient to reproduce observed patterns. Redox oscillations driven by environmental variability play an indispensable role in pattern formation. Environmental variability creates a range of conditions at the same site for various processes in SDF to occur, albeit in different temporal windows of differing durations. In effect, environmental variability determines mean rates of pattern-forming processes over the timescale relevant to pattern formation and modifies the likelihood that pattern formation will occur. As such, projected climate change might significantly alter many self-organized systems, as well as the ecological consequences associated with the striking patterns they present. This temporal dimension of pattern formation is previously unreported and merits close attention.Statement of SignificanceIron reactions create redox features in soils around the world. This study investigates mechanisms forming regularly-spaced iron stripes in upland soils. Upland soil redox conditions, driven by environmental variability, are highly dynamic. We show that two sets of scale-dependent feedbacks are coupled to form redox patterns and environmental variability plays a critical role in both. Significantly, environmental variability creates opportunities for various pattern-forming processes to occur at the same site in different temporal windows and determines mean process rates over the timescale relevant to pattern formation. Hence, environmental variability dictates the likelihood of pattern formation. Such a critical role of the temporal dimension in spatial self-organization has rarely been reported and has great potential for application in other self-organized ecosystems.

Freshwater ecosystems receive substantial terrestrial organic matter (t-OM) from surrounding landscapes. How the t-OM is transferred affects aquatic food webs and global carbon budgets. Previous studies have emphasized terrestrial support of aquatic ecosystems via direct organic carbon subsidy, overlooking the dissolved inorganic carbon (DIC) pathway, that is, DIC from t-OM decomposition is used by aquatic primary producers, supporting higher trophic levels. Using 2-year13C and15N measurements of phytoplankton, zooplankton, terrestrial plants, sediments, dissolved and particulate organic matter from seasonal wetlands, we found that while zooplankton (mid-trophic consumers) used t-OM directly in January, in March and May zooplankton were mainly supported by phytoplankton that used DIC recycled from t-OM mineralization and methanogenesis. The dominance of this DIC pathway is tightly coupled with the characteristics of these systems. Mineralization and methanogenesis of rich fresh t-OM resulted in supersaturated CO2with high CO2and CH4emissions. Atmospheric CO2diffusion and methanogenesis significantly enrichedδ13Cof DIC, leading to wide variations inδ13Cof DIC between -12.4 and 6.7 ‰, which provided ideal conditions to quantify carbon cycling in these widespread but understudied ecosystems. Our findings draw attention to potentially high carbon emissions from temporary freshwater ecosystems that are being increasingly common under warming climate.

Background Reaction kinetics was an important tool for quantitative expression of micro-chemical processes. In this study, a kinetic evaluation method of microwave liquid-phase desorption mechanism was established, which was of great value to reveal the non-thermal effect of microwave desorption. Methods Desorption kinetics of basic aluminum sulfate (aluminum base) desulfurization rich liquid were monitored with a microwave simultaneous cooling system. The effect of microwave power on its chemical reaction was investigated by linear and nonlinear regression analysis. Significant findings The kinetic analysis showed that the pre-exponential factor and activation energy decreased with the increase of microwave power, and the dependence on microwave power was more consistent with the first-order linear model and the second-order polynomial model. At the same temperature, the microwave desorption rate was 1.3–2.6 times that of water bath thermal desorption. At the same desorption reaction rate, the microwave desorption temperature was 10 K–20 K lower than that of thermal desorption. Compared with thermal desorption, although the reaction order did not change under different microwave power, the pre-exponential factor and activation energy decreased, and the reaction rate constant was about 1.1–2.1 times that of the same temperature.

A microwave liquid-phase desorption technique for enhancing mass transfer with chemical dissociation has been proposed for the first time. In this paper, the static desorption system of basic aluminium sulfate (aluminium base) desulfurization rich liquid was investigated through an experiment and numerical simulation. By establishing a desorption mass transfer rate equation and the internal heat source and concentration source of microwave desorption, the mechanism of microwave desorption thermal and non-thermal effect was revealed. Results showed that desorption mass transfer rate (NSO2) is related to temperature, pressure, film thickness and liquid SO2 concentration (CSO2). Desorption temperature and gas film thickness have limited influence on desorption performance, while CSO2 and liquid film thickness have significant influence. The increase in NSO2 per unit reduction of liquid film thickness increased five times when liquid film thickness decreased from 50 to 30 and then to 10 μm. At the same film thickness, microwave thermal desorption was controlled on the basis of desorption temperature and time, and microwave power only changed the heating rate. The important value of microwave non-thermal effect was that CSO2 was greatly increased by enhancing the chemical dissociation ability of SO2. At 800 W, the NSO2, mass transfer rate chemical influence factor (Φ) and physical influence factor (ψ) of thermal desorption end point were 0.98, 0.92 and 1.07 times those at 480 W, respectively, at the same film thickness, whereas microwave desorption end point were 3.28, 3.18 and 1.03 times, respectively, those at 480 W. Furthermore, the impact ratio (X) between non-thermal and thermal effects on NSO2 of microwave desorption was between 6.3 and 15.5 at 800 W and between 2.8 and 10.6 at 480 W. High microwave power showed stronger non-thermal effect capability.

The underlying physical and biogeochemical mechanisms associated with low dissolved oxygen (DO) levels below 5 mg L −1 were examined through field data analyses and water quality modeling of the lower 40 miles of the Minnesota River. Insights into flow and water quality data of nineteen years (1999–2017) at five sites demonstrate that low DO levels parallel the obvious longitudinal (upstream-to-downstream) decline in phytoplankton biomass and increase in ammonium nitrogen (NH4) and dissolved orthophosphate (PO4) in the last 22-mile river reach (i.e., navigation channel) during late summer low flow conditions. River discharge is inversely related to the magnitude of the longitudinal change in DO, phytoplankton biomass, NH4 and PO4, indicating that the late summer low flow hydrodynamics in the navigation channel with a longer residence time, deeper water and slower velocity provide an extended opportunity for the biogeochemical reactions involving phytoplankton, DO and nutrients. Moreover, the ratio of the longitudinal decline in DO versus the longitudinal increase in NH4 is particularly close to the Redfield O:N ratio, suggesting that the decline in DO and increase in nutrients most likely result from the decomposition of phytoplankton detritus under aerobic conditions. This is further proved by the water quality modeling of the lower Minnesota River. The primary reasons for impaired water quality are substantially elevated sediment oxygen consumption and nutrient release derived from the decomposition of settled phytoplankton detritus in the navigation channel. Therefore, we recommend that active prevention of abrupt phytoplankton blooms and collapses through regulation of river discharge and local hydrodynamics may assist in maintaining acceptable water quality in eutrophic rivers with a high level of phytoplankton biomass.

Background Previous studies have suggested that metabolic syndrome (MetS) and its component conditions are linked to the development of many benign or malignant diseases. Some studies have described relationships among metabolic syndrome or diabetes and liver cancer, but not many articles described the relationships between MetS and cirrhosis, acute hepatic failure, end-stage liver disease, and even death. However, liver cancers, cirrhosis, acute hepatic failure, end-stage liver disease, and liver-related mortality—collectively described as liver-related events (LREs)—may have different relationships with MetS. We undertook this meta-analysis to examine the association between MetS and LREs, and to determine whether geographic region or hepatitis B virus (HBV) positivity might influence the association. Methods Relevant studies were identified from PubMed, EMBASE, and the Cochrane database. Two reviewers independently searched records from January 1980 to December 2017. The search terms included ‘metabolic syndrome’, ‘diabetes mellitus’, ‘insulin resistance syndrome’, and ‘metabolic abnormalities’, combined with ‘cirrhosis’, ‘hepatic fibrosis ’, ‘hepatocellular carcinoma’, ‘complication’, ‘LRE’, ‘HCC’, ‘liver-related events’, and ‘liver cancer’. No language restriction was applied to the search. We chose the studies reporting an association between MetS and LREs. We used Begg’s and Egger’s tests and visually examined a funnel plot to assess publication bias. All analyses were conducted in Stata 14.0 software. Results There were 19 studies (18 cohort and 1 case-control) included in the analysis, with a total of 1,561,457 participants. The subjects’ ages ranged from 18 to 84 years. The combined analysis showed an overall 86% increase risk of LREs in cases with MetS (RR: 1.86,95% CI: 1.56–2.23). The funnel plot was asymmetrical, and the Egger’s test p values showed a publication bias in this meta analysis. However, through the trim and fill method, we obtained a new RR value for LREs with MetS of 1.49 (95% CI: 1.40–1.58, p = 0.000). There was no obvious difference with the two answers, so we concluded that the results were robust. For hepatitis B positive patients, the RR for MetS and LREs was 2.15 (95% CI:1.02–4.53, p = 0.038), but for the hepatitis B negative patients, the RR was 1.85 (95% CI:1.53–2.24, p = 0.000). And for non-Asians, the RR for MetS and LREs was 2.21 (95% CI: 1.66–2.69, p = 0.000), while for Asians, the RR was 1.73 (95% CI: 1.35–2.22, p = 0.000). Conclusions This meta-analysis showed that MetS is associated with a moderately increased risk of LREs prevalence. Patients with MetS together with hepatitis B are more likely to develop hepatic events. For non-Asians, MetS is more likely to increase the incidence of LREs.

Background: Clinical management and the prognosis of endometrial cancer is closely related to cervical invasion. The diagnostic performance of MRI for detecting cervical invasion has not been comprehensively assessed. We aim to evaluate the diagnostic accuracy of magnetic resonance imaging (MRI) in the preoperative assessment of cervical invasion and to analyze the influence of different imaging protocols in patients with endometrial carcinoma.Methods: An extensive search of articles about MRI in assessing cervical invasion in patients with endometrial carcinoma was performed in PubMed, Embase, Web of Science, Cochrane Library, and Clinical Trials from January 2000 to July 2019. Two reviewers independently evaluated the methodological quality of each study by using the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2). Diagnostic accuracy results and additional useful information were extracted. Pooled estimation data was obtained by statistical analysis. Results: A total of 42 eligible studies were included in the meta-analysis. Significant evidence of heterogeneity was found for detecting cervical invasion (I2 = 74.1%, P = 0.00 for sensitivity and I2 = 56.2%, P = 0.00 for specificity). And the pooled sensitivity and specificity of MRI were 0.58 and 0.95 respectively. The use of higher field strength (3.0 T) demonstrated higher pooled sensitivity (0.74). Using diffusion-weighted imaging (DWI) alone presented higher pooled sensitivity (0.86) than using other sequences. Studies that used dynamic contrast-enhanced MRI (DCE-MRI) alone showed higher sensitivity (0.80) and specificity (0.96) than that used T2-weighted image (T2WI) alone.Conclusions: MRI shows high specificity for detecting cervical infiltration in endometrial carcinoma. Using DWI or a 3.0-T device may improve the pooled sensitivity. The use of DCE-MRI demonstrate higher pooled sensitivity and specificity than T2WI.

Numerous studies have investigated the prognosis value of the liver stiffness measurement (LSM) by transient elastography in assessing the risk of liver‐related events (LREs) and all‐cause mortality in patients with chronic liver disease (CLD). However, the shape of the dose–response relationship between them remains unclear. We searched PubMed, Embase, the Cochrane Library, and reference lists of articles for studies published up to July 1, 2017, that assessed the LSM in predicting LREs and all‐cause mortality among subjects with CLD. Fifty‐four observational cohort studies with 35,249 participants were included. Summary relative risks (RRs) were calculated using a random‐effects model, and a restricted cubic spline function was used to model the dose–response association. LREs and all‐cause mortality were increased in subjects with a high LSM (LRE: RR, 7.90; 95% confidence interval [CI], 5.65, 11.05; I 2 = 71.6%; all‐cause mortality: RR, 4.15; 95% CI, 2.56, 6.72; I 2 = 68.5%). For each unit increment of liver stiffness, the summary RR was 1.06 (95% CI, 1.06, 1.07; I 2 = 74.6%) for LREs and 1.06 (95% CI, 1.04, 1.07; I 2 = 55.7%) for all‐cause mortality. A positive relationship with a nonlinear trend for LSM with LREs and all‐cause mortality was examined by a dose–response meta‐analysis (P < 0.001). When stratified by etiology, a nonlinear association was also found in patients infected with hepatitis C virus and those coinfected with hepatitis C virus and human immunodeficiency virus. In contrast, there was no evidence of departure from linearity among patients with hepatitis B virus infection (P nonlinearity = 0.072). Conclusion: LSM is useful in screening LREs and all‐cause mortality in patients with CLD. Further studies are warranted in assessing the application of LSM in monitoring the risk of LREs and all‐cause mortality in clinical practice. (Hepatology Communications 2018;2:467‐476)

Life cycles of riparian vegetation are substantially impacted by river flow regime, groundwater and morphodynamics. The polygon-based riparian vegetation simulation module (RVSM) was developed and integrated into HEC-RAS one-dimensional flow model to predict spatially-explicit seed germination, seedling establishment, plant growth and mortality in response to fluvial processes. The HEC-RAS – RVSM system was applied to the Sacramento River reach to evaluate its capability in modeling temporal and spatial changes of riparian vegetation and the interactions between flow and riparian vegetation dynamics. River hydraulics, groundwater level and five vegetation types of the study reach were simulated for the eight-year (1999–2007) period. Model results demonstrate that the HEC-RAS – RVSM system reproduced the coverage increase of cottonwood, riparian shrub, invasive species and grass as well as the coverage decrease in mixed forest over the eight-year. The RVSM was able to capture sites for cottonwood establishment observed on certain point bars. The modeled variations of cottonwood coverage in response to dynamic flow regime facilitated determining and managing environmental flow for riparian vegetation restoration. The height of capillary fringe and root growth rate were two key parameters influencing riparian vegetation distribution.

Proton pump inhibitors (PPIs) are among the most commonly prescribed medications in the US, but their safety in cirrhosis has recently been questioned. We performed a meta-analysis of observational studies to evaluate the impact of PPIs on adverse clinical outcomes in the setting of chronic liver disease (CLD). We searched several databases from inception to 26 May 2019 to identify comparative studies evaluating the effect of PPIs in CLD. Outcomes of interest were the associations between PPIs use and the occurrence of hepatic encephalopathy, hepatocellular carcinoma, spontaneous bacterial peritonitis, bacterial infections, and mortality in CLD. We performed a meta-analysis in accordance to the PRISMA guidelines. Of 14,662 papers evaluated, 47 studies with 169,806 participants were identified. Of these, 35 were cohort studies and 12 were case–control studies. The pooled odds ratio (OR) for hepatic encephalopathy in individuals with PPI users, compared with those without, was 2.31 (95% CI 1.63–3.28). The pooled OR for spontaneous bacterial peritonitis in individuals with PPI users was significantly higher compared with non-PPI users (OR = 1.72, 95% CI 1.42–2.09). Results were also consistent with a higher risk of the bacterial infections and mortality in PPI users compared with non-PPI users. For hepatocellular carcinoma, the final conclusion cannot be drawn because of the limited number of studies. This study identifies a significant relationship between PPIs therapies and several specific adverse clinical outcomes in CLD. However, these results should be carefully considered given the potential selection bias and unmeasured confounding variables in observational studies, it may be reasonable to re-evaluate the need for PPIs in patients with CLD.

Objectives To assess the diagnostic accuracy of magnetic resonance imaging (MRI) for detecting myometrial invasion, cervical invasion, and lymph node metastases in endometrial cancer. Materials and Methods A systematic literature search was performed in PubMed, Embase, Cochrane Library, Web of Science, and Clinical trials. The methodological quality of each study was assessed by using the standard Quality Assessment of Diagnostic Accuracy Studies-2. Statistical analysis included evaluating publication bias, assessing threshold effect, exploring heterogeneity, pooling data, meta-regression, forest plot, and summary receiver-operating characteristics curves construction. Results Fourteen studies could be analyzed. For detecting deep myometrial invasion, the pooled sensitivity and specificity were 0.79 and 0.81 respectively, and patients younger than 60 years old demonstrated higher sensitivity (0.84) and specificity (0.90). The diagnostic accuracy is highest by jointly using T2-weighted image, dynamic contrast-enhanced MRI, and diffusion weighted imaging to detect the deep myometrial invasion. There were low sensitivity and high specificity for the diagnosis of cervical invasion (0.53, 0.95), cervical stromal invasion (0.50, 0.95), pelvic or/and para-aortic lymph node metastases (0.59, 0.95), and pelvic lymph node metastases (0.65, 0.95). Conclusion MRI has good diagnostic performance for assessing myometrial invasion in patients with endometrial cancer, especially in patients younger than 60 years old. Dynamic contrast-enhanced MRI and diffusion weighted imaging can help improve sensitivity and specificity for detecting myometrial invasion. MRI shows high specificity for detecting cervical invasion and lymph node metastases in endometrial cancer.

Determining the roughness of riparian vegetation is often a challenge in river hydraulic modeling. A large number of quantitative methods have been developed, but none of them have been int...

Low-grade metallurgical silicon (MG-Si, purity ∼98%–99%, $1/kg) with annual production over six million tons is an attractive feedstock to produce active photocatalysts. However, MG-Si is known as an electronically dead material due to serious charge recombination associated with high metal impurity levels. Upgrading MG-Si close to solar grade is essential to achieve desired performance; nevertheless, the traditional silicon refinement process is cost ineffective, has high energy consumption, and causes environmental pollution. Here, we address this critical issue by employing a room-temperature one-step Cu-assisted chemical etching (CuACE) process, which successfully purifies MG-Si into active photocatalysts. We discover that the use of reducing agent (H3PO3) instead of commonly employed oxidant (H2O2) in the etchant system induces a novel phenomenon called “chemical cracking effect”. This effect significantly decreases the granularity of bulk MG-Si particles and simultaneously exposes fresh surfaces car...

Transport and fate of phytoplankton blooms and excessive nutrients along salinity and turbidity gradients of a river-estuary continuum could determine when and where impaired water quality occurs. However, the general spatiotemporal patterns, underlying mechanisms and their implication for water quality management are not well understood. This study reveals typical seasonal variations and longitudinal patterns of phytoplankton, dissolved oxygen (DO) and nutrients (C, N, and P) in the lower St. Johns River estuary in Florida based on 23 years of data and a model which spans 3 years. Evident declines in freshwater phytoplankton and DO concentrations were observed in the freshwater-saltwater transition zone and the estuarine turbidity maxima along the river-estuary continuum. Observations show that most cyanobacteria blooms originating from upstream lakes collapsed in the freshwater-saltwater transition zone where salinity was greater than 1 ppt, but data analysis and model simulation both indicate salinity stress was not the sole reason, other factors such as changes in hydrodynamics and river morphology also contributed to the bloom crashes. Inorganic nutrients (ammonium, nitrate, and phosphate) exhibited inverse longitudinal patterns with phytoplankton. Due to algal uptake, summer concentrations of inorganic nutrients were low in the freshwater, but substantially elevated in the marine reach as a result of large point source inputs and nutrient regeneration from organic detritus. However, because of strong river-ocean mixing, the dramatic increase in nutrients did not promote a phytoplankton bloom in the local marine reach. The nutrients were eventually transported into coastal waters or oceans where they fueled phytoplankton blooms. Our findings highlight that strategies for nutrient reduction and phytoplankton bloom management should be developed beyond local reaches and across a river-estuary-ocean continuum, exploring the possibility that freshwater phytoplankton blooms and excessive nutrients may be transported to downstream estuaries, coastal waters and even oceans that are vulnerable to poor water quality.

Summary Larval abundance of fish species downstream of large dams generally declines with changes in flow and thermal regime caused by dam operation. Fish conservation strategies in dammed rivers may need to be modified because adjustments in life-history or spawning behaviour are necessary for adult fishes to survive in modified environments. We used genetic programming to identify significant pre- and post-dam environmental factors affecting larval abundance of four major Chinese carp species in the Yangtze River downstream of the Three Gorges Dam and to quantify their relationships with larval abundance during a 13-year period (1997–2009) that encompasses seven pre-dam years and six post-dam years. Significant pre-dam factors included duration and rise rate of flow increase. With a nonlinear correlation, larval abundance slightly increased with duration of flow increase (Duration) when 2 days ≤ Duration ≤ 4 days, but significantly increased with Duration when 5 days ≤ Duration ≤ 8 days. With an approximate linear correlation, larval abundance increased with average daily rise rate of flow increase (QRavg) when QRavg ≤ 2000 m3 s−1 day−1. Timing of flow increase was the most significant post-dam factor, with the majority of adult carp spawning 55–80 days after water temperature at Yichang gauge station reached 15 °C. Duration of flow increase remained significant and its relationship with larval abundance remained unchanged, but rise rate of flow increase was no longer identified as a significant factor. Water temperature became significant with larval abundance decreasing slightly with maximum water temperature of flow increase (WTmax) when 22 °C ≤ WTmax ≤ 26 °C. Changes in the significance of individual environmental factors were caused by adaptation to thermal regime alterations through a gradual delay in spawning time. Because the delayed spawning period was much closer to, or even overlapped with the main flood season, magnitude and rise rate of flow increase and water temperature all increased. These changes, coupled with a lack of long flow increase (Duration ≥ 5 days), the occurrence of dissolved gas super-saturation and the disappearance of most spawning grounds in the Three Gorges Reservoir, resulted in a substantial decline in carp larval abundance of the middle Yangtze River. Variation in the significant factors and their relationships to larval abundance implies that mimicking a natural flow regime without accounting for fish response to environmental changes may not provide the environmental flows needed to enhance native fish spawning. Based on pre- and post-dam relationships between significant factors and larval abundance, we recommend that in order to enhance the four carp species spawning, the Three Gorges Reservoir should plan at least one flow release with increased discharges (Duration ≥ 5 days, 900 ≤ QRavg ≤ 3000 m3 s−1 day−1 and discharge ≤ 30 000 m3 s−1) between 15 June and 20 July when water temperature is

Large dams often alter flow and thermal regimes downstream, resulting in fish spawning delays and larval abundance declines. Accurate prediction of the delayed spawning period under changed thermal regime is critical for selecting a correct timing to modify dam operation and to release the environmental flow needed to enhance fish spawning. We used correlation analysis to investigate the relationship between thermal regime alteration and spawning delay of the four major Chinese carps (FMCC) below the Three Gorges Dam in the Yangtze River, China, using a 13-year ecological data series (1997–2009). Eighteen variables were defined to quantify thermal regime and related to two variables representing spawning timing. Our results demonstrate that the start of FMCC spawning has been delayed from early May to middle June since the Three Gorges Dam initiated operation in 2003. Water temperature declines of 2 °C–4 °C in March, April and May (a critical period for gonad development) were the principal reason for the observed spawning delay. The variable most associated with spawning timing was the arrival date of the cumulative temperature needed for gonad development from stages IV to V (DDegDayIV–V), which describes the long-term impacts of the timing, magnitude and duration of thermal regime upon gonad development. Only the cumulative temperature for gonad development and the minimum temperature for FMCC spawning (18 °C) are both satisfied, the occurrence of suitable flow conditions, that is, flow increase or flash flood, would produce a successful spawning event. Consequently, we suggest that the experimental flow increase process of the Three Gorges Reservoir aimed at enhancing FMCC spawning should initiate after 15 June when the requisite thermal regime can be met. Copyright © 2013 John Wiley & Sons, Ltd.

The current environmental flow assessment of Chinese rivers is thought to have three shortcomings: The first is that environmental flow requirements of reservoirs in dammed rivers are usually not explicitly considered; the second is that enough attentions have not been paid to the inherent links between flow regime and ecological processes; the third is that most studies focus on the variable range of merely one hydrological element such as discharge needed by riverine ecosystems. Here, first proposed is a holistic method for environmental flow assessment, the flow-ecological response relationship method that is suitable for large rivers with relatively abundant ecological data. Based on the conceptual models and quantitative relationships between flow and ecological response, this method comprehensively considers the ecological conservation requirements of both reservoir and its downstream reach. Then, it is applied to assessing the environmental flows of the Three Gorges Reservoir and its downstream reach by the following steps: 1) Construction of conceptual models of flow-ecological response; 2) identification of ecological targets of environmental flows and their key periods; 3) development of the quantitative relationships between hydrological indicators and ecological indictors; 4) preliminary assessment of environmental flow according to the tradeoff between ecological targets and water demands of human. The environmental flow hydrographs obtained have explicit ecological conservation targets, time schedule of achieving each target, and characteristics of multiple hydrological elements such as flow, water level, frequency, timing, duration and rate of change. The case study has tested the reasonability and feasibility of this method, and the results of this study are expected to provide technical support and decision reference for improving the operation of the Three Gorges-Gezhouba cascade reservoirs.

Information hidden in the characteristics and relationship data of a cascade hydropower stations can be extracted by data-mining approaches to be operation rules and optimization support information. In this paper, with Three-gorge and Gezhouba cascade hydropower stations as an example, two operation rules are proposed due to different operation efficiency of water turbines and tight water volume and hydraulic relationship between two hydropower stations. The rules are applied to improve optimization model with more exact decision and state variables and constraints. They are also used in the population initiation step to develop better individuals with culture algorithm with differential evolution as an optimization method. In the case study, total feasible population and the best solution based on an initial population with an operation rule can be obtained with a shorter computation time than that of a pure random initiated population. Amount of electricity generation in a dispatch period with an operation rule also increases with an average increase rate of 0.025%. For a fixed water discharge process of Three-gorge hydropower station, there is a better rule to decide an operation plan of Gezhouba hydropower station in which total hydraulic head for electricity generation is optimized and distributed with inner-plant economic operation considered.

Background Serum gamma-glutamyltransferase (GGT) elevation likely contributes to cardiovascular (CV) mortality, however it has remained unknown whether a dose-response relationship exists between serum GGT and CV mortality. Methods We searched the PubMed, EMBASE, and Cochrane library databases for prospective cohort studies published up to October 2, 2016. Summary hazard ratios (HRs) with their corresponding 95% confidence intervals (CIs) were calculated using a fixed effects model. Findings Nine prospective studies, including 527,589 participants and more than 7,011 cases, were included in this meta-analysis. For the moderate, high, and highest levels of GGT, the pooled HRs of CV mortality were 1.11 (95% CI = 1.04–1.19), 1.29 (95% CI = 1.21–1.38) and 1.59 (95% CI = 1.47–1.72), respectively (all p < 0.05 as compared to the lowest levels of GGT). Additionally, the HR per incremental increase of GGT by 10 U/L was 1.10 (95% CI = 1.08–1.11). Evidence of a positive relationship with nonlinear trend for GGT elevation with CV mortality in females was found (P = 0.04 for nonlinearity). However, a linear model was better fit to illustrate the GGT-CV mortality among males (P = 0.304 for nonlinearity). Conclusions These findings indicate that serum GGT activity within the reference interval is positively associated with increased risk of CV mortality in a dose-response manner.

The origin of the photocurrent enhancement and the overpotential reduction in solar water splitting employing nanostructured silicon is still a matter of debate. A set of tapered Si nanowires (SiNWs) has been designed for clarifying the impact of nanostructured Si on the hydrogen evolution reaction (HER) while precisely tailoring several interference factors such as surface area, light absorption and surface defect density. We find that defect passivation by KOH achieved by tapering is much more beneficial than the optical gain. Surfactant-mediated modification of SiNWs is capable of engineering the band structure. As a result, we suggest a guideline for nanostructured Si photoelectrodes optimized for the HER.

The purity of metallurgical-grade silicon can be increased to solar grade by metal-assisted chemical etching (MaCE). Metal impurities are removed during the formation of porous silicon nanowires (NW). We present a chemical etching model to explain the different levels of chemical reduction for various metals with pore growth during etching. Our study not only highlights the importance of controlling the metal ion concentration and selecting metal types for engineering porous features in NWs, but also explains the reason for the difficulty in removing noble metals such as Cu.