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A pumped storage power station operates on the principal of multiple pump-turbines sharing one tunnel. However, safety is a concern, particularly under one-after-another load rejection of multiple pump-turbines. In this study, we have implemented a model experiment based on water column separation experiment under the condition of one-after-another load rejection of a pumped storage model experimental platform with two pump-turbines sharing one tunnel. The results show that the unit with water column separation, which is Unit # 2, has the worst moment when it rejects full load 0.8 s after Unit #1. At this condition, the wall pressure of the draft tube of unit # 2 attains the vapor pressure and reverse water hammer pressure attains the maximum value of 6.8 m during water column bridging. However, the reverse water hammer pressure was 290 m in prototype unit. Under one-after-another load rejection, water column separation occurs when the draft tube attains the second extreme value, and the unit located in the turbine braking condition area. It was observed that the pressure pulsation frequency of the draft tube after one-after-another load rejection is composed of two parts. First, pressure pulsation frequency caused by swirling flow with a value of 0.4 f / f n and second, a broadband of 40–200 Hz generated by the reverse water hammer due to water column bridging and structural response of the unit. • Clarifying the characteristic parameters of the unit at the worst moment and its adjacent moment. • Analyzing water column separation phenomenon at different intervals of one-after-another load rejection. • Analyzing the reverse water hammer pressure and pressure pulsation characteristics of water column bridge. [ABSTRACT FROM AUTHOR]

Whether the superposition of pressure pulsation and water hammer pressure caused by the fast closing of guide vanes causes water column separation in draft tube inlets is a hot topic in engineering and academic fields. It is also not known whether the bridging of water column separation endangers the operation of the units. This study uses a model pumped storage power station platform with two units to perform water column separation. Data on the pressure pulsation at different measurement points, discharges, and speeds are collected by an acquisition system, whereas the development process of water column separation is characterized by a high-speed camera. The measured pressure is decomposed into the water hammer pressure, which migrates with the unit operation point and pressure pulsation. The test results reveal that the pressure in the inlet section of the draft tube below the vaporization pressure that lasts for several seconds is a sufficient and necessary condition for water column separation to occur. The water hammer pressure has a significant influence on the water column separation, while low-frequency pressure pulsation has less influence. Water column separation is divided into four stages: starting, improvement, separation, and bridging. The main frequency of the pressure pulsation in the water column separation process is the frequency of the water hammer caused by load rejection and has a value of 0.47 f / f n. Cavity bridging generates a frequency of 0.30 f / f n. The flow-speed curve remains in the braking condition of turbine for 1.25 s. The separation and part of the bridging stage occur under the braking condition of turbine. • The development stages of water column separation are proposed. • The frequency and amplitude of pressure pulsation in different stages are proposed. • The migration trajectory of water column separation is analyzed. • The occurrence criterion of water column separation is discussed. [ABSTRACT FROM AUTHOR]

The development of high-head pumped-storage projects presents various opportunities and challenges. One challenge is the operational stability of pumped-storage power plants, which is closely associated with the characteristics of pump-turbines. In this study, the design and experimental verification of the hydraulic performance of a pump-turbine runner with splitter blades are investigated. The effects of several main parameters on the performance curve and S-shaped characteristics of pump-turbines in turbine mode are examined via numerical simulation. Subsequently, model tests are conducted to validate the improvements in the performance curve, including a comparison of the S-shaped characteristic curve at a constant guide vane opening and under the same initial conditions. An emergency load rejection test based on the same guide vane closing scheme is performed to verify improvements in transient pressure in the spiral case, draft tube, and rotational speed. The results confirm the enhancement in the S-shaped characteristics and transient global parameters of the splitter blade design. Furthermore, a reduction in pressure pulsation intensity in the vaneless space during off-design conditions is confirmed. [ABSTRACT FROM AUTHOR]

Abstract: Strategies to enhance the efficacy of DNA vaccination against malignancy remain to be established. In this study, a plasmid expressing a tumor antigen incorporated into the signal peptide of human IL-2 was tested as a DNA vaccine in a murine model system. Results showed that antigen-specific CTL responses were elicited by intramuscular injection of these plasmids. Importantly, compared with a minigene vector expressing the same epitope, the OVA epitope-incorporated, IL-2 expression plasmid vaccination was more effective in protecting mice from OVA-expressing tumor challenge. The improved efficacy appears to result from enhanced antigen presentation as well as the immunostimulatory activity of IL-2. This approach may provide new perspectives in designing cytokine-adjuvant DNA vaccines for clinical applications. [Copyright &y& Elsevier]

With the increase in the designed net head and output capacity, the operational stability of the pump turbine, which is the core component of a pumped storage power station, requires further investigation. The originality of the current research lies in the analysis of the pressure pulsation characteristics in the vaneless space of a pump-turbine runner designed with splitter blades. Under the designed net head and high-flow-rate conditions, the dominant frequency of the pressure pulsation in the vaneless space corresponds to half the total number of runner blades, 4 f n. As the flow rate decreases, a blade-passing frequency of 8 f n corresponding to the total number of runner blades was observed. Subsequently, the amplitude of 8 f n increased, which gradually became the dominant frequency, whereas that of 4 f n diminished. The contribution of current research is that the transition of the amplitude-frequency characteristic of the rotor-stator interaction of pump-turbine runners with splitter blades is revealed, which is significantly different from the analysis of equal-blade pump-turbines in the existing literature. For pumped storage power stations equipped with pump-turbine runners with splitter blades, it is necessary to consider the dominant frequency in the vaneless space to avoid the adverse effect of the transition of the dominant frequency of the rotor–stator interaction on the structural response of the station. [ABSTRACT FROM AUTHOR]

How to extract the running feature information and realize multi-type faults diagnosis is the key to carry out intelligent operation and maintenance of energy conversion machinery. The pumped storage unit (PSU) has various operating conditions, both energy storage and power generation. It may lead to diversified types of failures under the joint influence of hydraulic and mechanical factors. The existing data-driven models often show excellent diagnostic performance with laboratory-specific fault types or single subsystem but are not satisfactory when applying real operating scenarios or migrating to other devices. Therefore, a universal hydraulic-mechanical diagnostic framework integrating signal acquisition, feature extraction and fault recognition is proposed in this paper. In Stage 1, eight types of datasets caused by the hydraulic-mechanical coupling characteristics via abnormal on-field measurements form an on-site benchmark; for Stages 2 and 3, a novel refined composite multiscale cosine similarity Lempel-Ziv complexity method is proposed to quantify the various fault features based on multiscale signal processing and the nonlinear dynamics methodology, and random forests model is introduced to realize the efficient recognition of different status signals. Its core advantage is versatility, which is not limited to specific components but can be applied to different subsystems of pumped storage, such as hydraulic system (identification of vortex conditions, detection of hydraulic imbalances) and mechanical system (wear of shaft, bearing and runner). This framework is applied in the micro PSUs, the comprehensive experiments show that all evaluation indexes are above 92%. Various comparative analysis indicates that the framework is not only applicable to the detection and analysis of hydraulic anomalies but also has a competitive advantage in the diagnosis of hydraulic-mechanical faults. It is suitable for fault detection of different subsystems in real power stations, and also could be flexibly extended to other rotating energy storage systems, as a helpful tool to improve energy conversion efficiency and reduce maintenance cost. [Display omitted] • Building a universal hydraulic-mechanical diagnostic framework. • Eight types of datasets caused by the hydraulic-mechanical coupling characteristics form an on-site benchmark. • Verifying the superiority of the framework by applying in the micro pumped storage system. • Providing a potential tool to improve energy conversion efficiency and reduce maintenance cost. [ABSTRACT FROM AUTHOR]

Graphical Abstract Unlabelled image Abstract Background Interleukin-35 (IL-35) has recently been identified as an immunosuppressive cytokine that has been used as a potential therapy for chronic inflammatory and autoimmune diseases. However, there remains a paucity of data regarding its potential benefits after integration into mesenchymal stem cells (MSCs). Methods We used a dextran sulfate sodium (DSS)–induced colitis mice model and treated them with IL-35-MSCs, MSCs or saline. The body weight was recorded daily and inflammatory processes were determined. Cytokine secretion by lamina propria lymphocytes (LPLs) and percentage of regulatory T cells (Tregs) were also measured. Results The data showed that mice in the two treated groups recovered their body weight more rapidly than mice treated with saline in the later stage of colitis. The colon lengths of IL-35-MSC–treated mice were markedly longer than those in the other two groups and the inflammation reduced significantly. Furthermore, the percentage of Foxp3 + Tregs increased significantly and the level of proinflammatory cytokines produced by LPLs decreased significantly in the IL-35-MSC–treated group. Discussion The results demonstrate that IL-35-MSCs could ameliorate ulcerative colitis by down-regulating the expression of pro-inflammatory cytokines. [ABSTRACT FROM AUTHOR]

The current development trend of China's hydropower is moving toward ultra-high heads, complex geological scenarios, ultra-large capacities, and the Tibetan region. The construction of hydropower stations with super-long headrace tunnels is conducive to overcoming the constraints of complex geological conditions and making full use of hydropower resources. However, these stations have unique technical problems that limit their commercial development, including pressure fluctuations during load rejection and the operational stability of the power-frequency regulation. In this study, a potential problem in hydropower stations with super-long headrace tunnels, the instability during load acceptance, is studied by combining prototype experiments with 1D transient numerical simulations. First, according to a test case using a prototype hydropower station, the instability phenomenon occurring during a simultaneous load acceptance of two Francis turbines in a hydropower station with a 20-km headrace tunnel is described. Next, using 1D steady-state and transient simulations, the factors leading to the instability are analyzed in detail. Finally, countermeasures for the safe operation of hydropower stations are proposed based on numerical simulations and supplementary prototype experiments. Hydropower stations with super-long headrace tunnels exhibit a characteristic where the net head decreases sharply with an increase in the flow rate. Therefore, prior to load acceptance, the maximum output achievable by the multiple units under the operating net head has to be carefully determined to avoid over-adjustment of the guide vane opening and detrimental phenomena such as operational instability and extremely low pressure in the draft tube. • Instability of a hydropower station with a super-long headrace tunnel has been discovered. • This instability has been reasonably simulated by one-dimensional transient simulation. • The effect of a super-long headrace tunnel on the operational instability has been revealed. • Countermeasures for the safe operation are proposed. [ABSTRACT FROM AUTHOR]

• Proposing an efficient nonlinear dynamics method named TPPI for quantifying anomaly information of PSUs. • Constructing a novel fault identification model of PSUs around the TPPI algorithm. • Validating the effectiveness of the proposed model through two case studies of the micro-PSHP. • Providing a potential tool to promote the intelligent construction of PSHPs. Efficiently extracting information from the massive data that characterize the abnormal condition is an important topic for pumped storage units (PSUs) operation and maintenance. Existing feature extraction methods for PSUs have weakened the connection between time and frequency domain features of signals, and the extracted information cannot fully represent the PSU operational state. Therefore, the paper proposes tensor Poincaré plot index (TPPI), a feature extraction method for quantifying PSU operation on multiple time and frequency scales. Firstly, the operational datasets are hierarchically decomposed and coarsely granulated to obtain components at different time and frequency scales. Secondly, the different components are sequentially transformed into Poincaré plots, and the key indexes of these plots are extracted, respectively. Finally, the proposed model is constructed by the extracted features and random forests. The proposed model is applied to two case of hydraulic anomaly identification and mechanical fault diagnosis, based on the measurement of the actual PSUs. The results show that indicators of this method are no less than 99.629 % and 99.660 %. In comparison experiments with 15 popular methods, the proposed model exhibits superior competitiveness, robustly affirming the advantages of the TPPI. The proposed method is helpful for promoting the intelligent construction of PSUs. [ABSTRACT FROM AUTHOR]

For a large hydropower plant (HPP) with long-distance tunnels, a surge tank needs to be installed to ensure the safety of the HPP during hydraulic transients (i. e., load changes in hydro-turbines). The head losses of the surge tank and its throttle are necessary conditions and evidence of the hydraulic design and one-dimensional (1D) simulation of the HPP. This study is conducted to investigate the head losses of a complex throttled surge tank for a refined 1D HPP simulation. Based on model experiments and computational fluid dynamics (CFD) simulations, the statistical laws of the total head loss coefficient are determined, and the dynamic refined formulas for the resistance and discharge coefficients are proposed. Finally, the proposed discharge coefficients are applied to refined 1D HPP simulations and compared with the traditional discharge coefficient. It is preliminarily revealed that the discharge coefficient undergoes a step change under load rejection and a continuous hump-shaped change under increasing loads. The water level results calculated using the proposed discharge coefficient differ by 1.69 m, i. e., 3.65% of the total height of the surge tank, compared with using the traditional discharge coefficient. This study can facilitate the understanding of hydraulic design and HPP optimization. [ABSTRACT FROM AUTHOR]

Aims Midkine is a multifunctional cytokine identified to be a promising cancer biomarker. We aimed to prospectively investigate serum midkine as a diagnostic and prognostic biomarker in differentiated thyroid cancer (DTC). Main methods 162 patients with thyroid nodules participated in the surgical cohort (post-surgical pathology proved 70 cases with DTC and 92 cases with benign thyroid nodules), 75 healthy subjects served as control. Diagnostic values of pre-surgical midkine and thyroglobulin for DTC were conducted by receiver operating characteristic (ROC) curves. 214 DTC patients participated in the 131 I treatment cohort. Prognostic values of pre- 131 I-ablative midkine and thyroglobulin to predict 131 I-avid metastases were performed by ROC curves. Metastasis-free survival was analyzed by the Kaplan–Meier method. Key findings Much better diagnostic capability of midkine than thyroglobulin was shown to differentiate DTC from benign thyroid nodules, with cut-off midkine value of 323.12 pg/ml and diagnostic accuracy of 75.31%. Nearly similar diagnostic capabilities of midkine and thyroglobulin were shown to distinguish DTC from normal participants. Pre- 131 I-ablative thyroglobulin demonstrated perfect ability to predict metastases, with cut-off value and diagnostic accuracy of 19.50 ng/ml and 96.73%. Midkine also performed well with a cut-off value and diagnostic accuracy of 504.71 pg/ml and 89.25%. DTC patients with midkine or thyroglobulin levels higher than those of thresholds (500 pg/ml or 20 ng/ml) showed a significantly worse 131 I-avid metastasis-free survival by the Kaplan–Meier method (P < 0.01). Significance Our results show that midkine is as good as or even better than thyroglobulin to screen patients with thyroid nodules for DTC before surgery, and to predict whether metastases exist before the first 131 I ablative therapy. [ABSTRACT FROM AUTHOR]

Aims Midkine (MK) is a multifunctional cytokine identified to be a promising cancer biomarker. Nuclear factor-kappa B (NF-κB) is an important transcription factor that plays a pivotal role in tumorigenesis. We aimed to investigate values of MK and NF-κB as markers for diagnosis and synchronous metastasis prediction in papillary thyroid cancer (PTC). Main methods 76 cases of PTC and 70 cases of multi-nodular goiter (MNG) were retrieved. The PTC group was further divided into subgroup 1 (16 cases with synchronous metastases) and subgroup 2 (60 cases without metastases). A retrospective review of demographic and clinical information was performed. Immunohistochemistry of MK, NF-κB p65 and Ki-67 was performed on paraffin-embedded specimens and results were quantified. Diagnostic values of the parameters were conducted by receiver operating characteristic (ROC) curves. Protein levels of MK and NF-κB p65 were then confirmed by Western blot. Key findings Immunoreactivities of MK, NF-κB p65 and Ki-67 were significantly higher in the PTC group than in the MNG group with good differential diagnostic capabilities. Moreover, immunoreactivities of all three parameters were significantly higher in subgroup 1 than in subgroup 2 with good synchronous metastasis predictive efficacies. Western blot showed that MK and NF-κB p65 protein levels in lesions from subgroup 1 were significantly higher than those from subgroup 2, both of which were significantly higher than in MNG lesions. Significance We discovered that MK and NF-κB immunohistochemistries can potentially be used for differential diagnosis between PTC and MNG, and for prediction of synchronous metastases. [ABSTRACT FROM AUTHOR]

The fast and stable regulation of pumped storage is a basic guarantee for supporting various scenarios of renewable energy system. The operator pursues sensitive tracking performance, while underestimates the dynamic characteristics of hydraulic system and damping characteristics of pumped storage unit (PSU). These may aggravate the wear-tear of PSU operation, and decrease the frequency stability of power system. Therefore, a systematical study of improving overall regulation performance is conducted by applying PSU modeling, co-optimization and operation evaluation. First, the novel small signal model is proposed and the high-order hydraulic damping model is further derived. Apart from the ultra-low frequency oscillation mode, a new frequency oscillation mode caused by surge tanks is captured. Second, the co-optimization strategy is presented to coordinate the stability-tracking conflict. And then a comprehensive evaluation model, integrating 14 indicators is conducted to quantify the PSU performance and its contribution to power system, driving the favorable decision making of operators. Compared with the original scheme, the overall performance of PSU is improved by 20.76%, at the cost of 10.88% tracking capacity. The comparison of three measures including 12 scenarios verifies the competitive advantage of co-optimization strategy in multi-machine system. This paper supplies a novel tool for performance enhancement of PSU. It may have potential value in the stability of renewable energy systems with multiple hydropower units. • A framework integrating novel model, co-optimization, and operation evaluation. • The small signal model is competitive in simulation efficiency and applicability. • The adaptable co-optimization strategy could coordinate the stability-tracking conflict. • The 12 scenarios verify the competitive advantage of proposed method. [ABSTRACT FROM AUTHOR]

• A comprehensive analysis of STAD pathogenesis was conducted. • High expression of DERL3 suppresses the invasion, migration, and proliferation of gastric cancer cells. • DERL3 was screened and validated as a candidate diagnostic marker gene of STAD. • DERL3 is a potential molecular target for the treatment of STAD. Gastric cancer is a common malignant tumor in the clinic with a high mortality rate, ranking the first among malignant tumors of the digestive system. Early gastric cancer exhibits no specific clinical symptoms and signs, and most of the patients were diagnosed as advanced gastric cancer. The prognosis is poor, and the 5-year overall survival rate is still lower than 30%, seriously threatening people's life and health. However, the pathogenesis of gastric cancer is still unclear. This study aimed to identify methylated differentially expressed genes in gastric cancer and to study the cellular functions and pathways that may be involved in its regulation, as well as the biological functions of key methylated differentially expressed genes. The gene expression data set and methylation data set of gastric cancer genes based on TCGA were analyzed to identify prognostic methylated genes. This study showed that the methylation of the DERL3 promoter was correlated with the clinical analysis of tumors. Further studies were conducted on genes co-expressed with DERL3, whose functions and pathways to inhibit gastric cancer were adaptive immune response, T cell activation, immune response-regulating pathway, cell surface on molecules, and natural killer cell-mediated cytotoxicity. Finally, cell proliferation assay, cell scratch assay, and cell invasion assay confirmed that DERL3 as a tumor suppressor gene inhibited the malignant evolution of gastric cancer. The analysis of key methylated differentially expressed genes helped elucidate the epigenetic regulation mechanism in the development of gastric cancer. DERL3, as a methylation biomarker, has a predictive and prognostic value in the accurate diagnosis and treatment of gastric cancer and provides potential targets for the precision treatment of gastric cancer. Not applicable. [ABSTRACT FROM AUTHOR]