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Abstract Objective This study investigates the MRI characteristics of primary and metastatic adult granulosa cell tumor with normal estrogen levels (AGCT-NEL) to enhance clinical understanding and diagnostic accuracy of this disease. Methods We collected clinical data from 10 patients with AGCT-NEL, confirmed by pathology, treated at our hospital from January 2016 to January 2024. We retrospectively analyzed the MRI features of primary and metastatic lesions from aspects such as shape, edge characteristics, MRI signal, and enhancement features. Results A total of 10 AGCT-NEL patients were included in this study, aged 28 to 81 years, with an average age of 54 ± 16 years. The primary tumors primarily presented as unilocular cystic, solid, and cystic-solid types. The solid components showed isointense to slightly hypointense signals on T1-weighted imaging (T1WI), slightly hyperintense signals on T2-weighted imaging (T2WI), and high signals on diffusion-weighted imaging (DWI), with possible internal hemorrhage or cystic degeneration. The cystic components exhibited low signal on T1WI, high signal on T2WI, uniform wall thickness, and no wall nodules, typically showing hemorrhagic fluid levels. Honeycomb and Swiss cheese signs are sometimes observed in cystic-solid tumors. All metastatic lesions were cystic (either unilocular or multilocular), presenting low signal on T1WI and high signal on T2WI, with no wall nodules and possible internal hemorrhagic fluid levels. The multilocular metastatic tumors demonstrated unevenly thickened partitions, also displaying honeycomb and Swiss cheese signs. Conclusion The MRI characteristics of primary and metastatic lesions in AGCT-NEL possess specific features, such as signs of hemorrhage, absence of wall nodules in the cystic portions of the tumors, and distinctive honeycomb and Swiss cheese signs, with metastatic lesions being cystic. Understanding these features can aid in improving preoperative diagnostic capabilities and reducing misdiagnosis.

IntroductionCerebral ischemia–reperfusion (IR) causes severe secondary brain injury. Previous studies have demonstrated that ferroptosis is involved in IR-induced brain injury. However, whether IR induces ferroptosis in brain microvascular endothelial cells (BMVECs) is not fully understood.Materials and methodsOxygen–glucose deprivation/reoxygenation (OGDR) was performed in bEND.3 cells to mimic IR injury in vitro, and a focal cerebral IR model was created in C57BL/6 mice. Transcriptomic sequencing of the cells was performed first, followed by bioinformatics analysis. Differentially expressed gene (DEG) enrichment analysis highlighted ferroptosis-related pathways.ResultsUsing Venn analysis, nine ferroptosis-related DEGs were identified, namely, Slc3a2, Slc7a11, Ccn2, Tfrc, Atf3, Chac1, Gch1, Lcn2, and Sesn2. Protein–protein interaction (PPI) analysis combined with molecular complex detection (MCODE) identified six hub genes, namely, Ddit3, Atf3, Sesn2, Trib3, Ppp1r15a, and Gadd45a. Spearman’s correlation analysis revealed a significant correlation between the hub genes and ferroptosis-related DEGs. After reperfusion, the levels of ferroptosis indicators were elevated, and the expression of the ferroptosis-related proteins Xc− and GPX4 decreased. SESN2 is a hub gene and key antioxidant regulator. SESN2 silencing reduced the expression of System Xc− and GPX4, whereas overexpression of SESN2 promoted the expression of System Xc− and GPX4.DiscussionThese results suggest that SESN2 is a negative regulator of ferroptosis. Enhancing the expression of SESN2 can alleviate ferroptosis through the activation of the System Xc−/GPX4 pathway. By integrating bioinformatics analysis with mechanistic exploration, this study revealed that ferroptosis plays a crucial role in IR-induced BMVECs injury, with SESN2 acting as a negative regulator via the System Xc−/GPX4 pathway.

Introduction: Angiogenesis is an essential feature of liver cancer. Tumor hypoxia results from abnormal vessel architecture. Numerous studies have sufficiently demonstrated that Tanshinone IIA (Tan IIA) can increase blood flow and enhance microcirculation. The objectives of this study are to: 1 assess the impact of Tan IIA on tumor angiogenesis and architecture, 2 determine the impact of Tan IIA on tumor hypoxia and susceptibility to Sorafenib, and 3 clarify the relevant mechanisms.Methods: CCK8 and flow cytometry measured cell proliferation and apoptosis, respectively. Tube creation assay was used to investigate medication effects on angiogenesis and structure. Drug effects on tumor development, metastasis, and hypoxic tumor microenvironment are assessed in an orthotopic xenograft model of liver tumors. Protein expression was measured by Western blotting and immunohistochemistry.Results: Our results demonstrated that Tan IIA could not reduce tumor proliferation or enhance Sorafenib’s anti-tumor effect in vitro. Nevertheless, it can prevent Sorafenib from demolishing the typical vascular structure and aid sorafenib in blocking the recruitment of vascular endothelial cells by liver cancer cells. Although Tan IIA cannot inhibit tumor growth in vivo, it can significantly boost Sorafenib’s inhibitory effect on liver cancer, alleviate tumor microenvironment hypoxia, and minimize lung metastasis. This effect may be achieved by reducing HIF-1α and HIF-2α expression via the PI3K-AKT signal pathway.Discussion: Our results reveal the mechanism of Tan IIA in normalizing tumor blood vessels, provide innovative concepts and approaches to overcome chemotherapy resistance, and provide a theoretical basis for the clinical transformation and usage of Tan IIA.

BackgroundPhosphoinositide 3-kinases (PI3Ks) are lipid enzymes that regulate a wide range of intracellular functions. In contrast to Class I and Class III PI3K, which have more detailed descriptions, Class II PI3K has only recently become the focus of functional research. PIK3C2A is a classical member of the PI3Ks class II. However, the role of PIK3C2A in cancer prognosis and progression remains unknown.MethodsThe expression pattern and prognostic significance of PIK3C2A in human malignancies were investigated using multiple datasets and scRNA-seq data. The PIK3C2A expression in renal clear cell carcinoma (KIRC) was then validated utilizing Western blot. The functional role of PIK3C2A in KIRC was assessed using combined function loss experiments with in vitro experiments. Furthermore, the correlation of PIK3C2A expression with tumor immunity was investigated in KIRC. The TCGA database was employed to investigate PIK3C2A functional networks.ResultsSignificant decrease in PIK3C2A expression in KIRC, demonstrated that it potentially influences the prognosis of diverse tumors, particularly KIRC. In addition, PIK3C2A was significantly correlated with the T stage, M stage, pathologic stage, and histologic grade of KIRC. Nomogram models were constructed and used to predict patient survival based on the results of multivariate Cox regression analysis. PIK3C2A knockdown resulted in significantly increased KIRC cell proliferation. Of note, PIK3C2A expression demonstrated a significant correlation with the infiltrating levels of primary immune cells in KIRC.ConclusionThese findings support the hypothesis that PIK3C2A is a novel biomarker for tumor progression and indicates dynamic shifts in immune infiltration in KIRC. Furthermore, aberrant PIK3C2A expression can influence the biological activity of cancer cells.

PurposeTo compare survival in different strategies, preoperative systemic treatment versus upfront surgery, in HER2-positive early breast cancer patients in the real world.MethodsAccording to the actual upfront treatment, eligible patients from 2012 to 2015 were classified as preoperative systemic treatment or upfront surgery group prospectively. The primary endpoint is disease-free survival; the second endpoint is overall survival. All the outcomes were examined in the propensity score matching model and inverse probability of treatment weighting model.ResultsIncluded in the analysis were 1,067 patients (215 in the preoperative systemic treatment group, 852 in the upfront surgery group). In the propensity score matching model (matching at 1:1 ratio), the disease-free survival of the preoperative systemic treatment group was significantly higher than that of the upfront surgery group (hazard ratio, 0.572, 95%CI, 0.371–0.881, P, 0.012). In the inverse probability of treatment weighting model, there was no significant difference in disease-free survival between the two groups (hazard ratio, 0.946, 95%CI, 0.763–1.172, P, 0.609). For overall survival, there was no significant difference between the two groups.ConclusionThe HER2-positive patients who accepted preoperative systemic treatment had better disease-free survival than those who underwent upfront surgery by real-world statistic methods.Clinical Trial RegistrationClinicaltrials.gov, identifier NCT04249440.

Electrically heated tobacco products (EHTPs) could release effective aerosol components from tobacco materials at relatively low temperatures without a burning phenomenon. It is essential to grasp the temperature distribution and release mechanism of key components in heated tobacco materials. The existing experimental studies have provided initial insights into the thermodynamic behavior of tobacco materials under various conditions. However, current numerical models are still in their early stages of development, with the majority failing to correlate heat transfer with component release. Based on this, a coupled numerical model of gas flow, heat transfer, and the release of key components in the electrically heated tobacco product is established in this study, which exhibits improvements in revealing the internal heat and mass transfer characteristics in the porous media of tobacco and is capable of evaluating the influence of component contents and product design parameters. The release rates of water, glycerol, and nicotine components are quantitatively described by the first-order Arrhenius formula, and the transport of heat and gas flow is simulated using the Navier-Stokes equation. The accuracy of the model is validated through experiments, including temperature monitoring at multiple measurement points and determination of residual contents in the tobacco substrate after each puff. The simulation results suggest that an appropriate component ratio and tobacco filler mass can enhance both the release amount and release efficiency of key components, and reducing either the diameter or length of the tobacco section can help to improve the heat transfer performance. A slower heating rate matched with longer preheating times enables the complementary release of water and glycerol components, which helps to regulate the uniformity of component content in the aerosol to some extent. This study helps to provide suggestions for the design and optimization of electrically heated tobacco products.

The terminal-connected series dynamic braking resistor (SDBR) is applied to assist the low-voltage ride-through (LVRT) of the doubly-fed induction generator (DFIG). With the fault current and switch-in of the SDBR, the stator voltage oscillates, thus the constant stator voltage drop assumption is invalid and the effect of the converter current control is weakened with the changing voltage-oriented reference frame. In this paper, the xy frame of the point of common coupling is applied to the converter control to avoid oscillation of the reference frame. The analytical expression of fault current with the SDBR and constant converter current control is derived. To evaluate the LVRT effect, the analytical analysis of the LVRT transient is carried out. The resistance of the SDBR is optimized based on an index combining the capabilities of the DFIG to provide the active power support and damp the electromagnetic torque oscillation. The uncertainties of the fault scenario are considered in the optimization algorithm by applying the probabilistic method. Simulation results show that the improved LVRT effect of the DFIG is realized with optimization to the SDBR resistance and its switch-in criterion.

To improve the DC-bus voltage and the switching frequency of the boost circuit and reduce the volume of the passive filter element and the heatsink, the SiC MOSFET should be used as the main switching device. It is necessary to keep the SiC MOSFET working in the synchronous working mode to minimize the on-state loss of the SiC MOSFET. In this mode, the dead-time should be inserted into the gate signals of two SiC MOSFETs in the bridge. However, because of the high switching frequency and the output capacitance of the SiC MOSFET and the freewheeling SiC diode, there will be a large loss during the dead-time. Thus, a self-adaption dead-time setting has been proposed in this paper. Firstly, it analyzes the detailed switching process and establishes the models around dead-times when the SiC MOSFET boost circuit works in the continuous and discontinuous mode respectively. Secondly, based on the analyses and models, the dead-time before the active SiC MOSFET turns on can be set as a fixed value calculated by the parameters of the SiC MOSFET and the driver board in the continuous mode ( $T_{\text {d1}}{}^{\text {con}}$ ) and can be set as a variable value relevant to the duty cycle, the switching period, the input and output voltage in the discontinuous mode ( $T_{\text {d1}}{}^{\text {discon}}$ ). Thirdly, also based on the analyses and models, the dead-time after the active SiC MOSFET turns off can be set as a variable value in the continuous mode ( $T_{\text {d2}}{}^{\text {con}}$ ), which depends on the real-time measured output voltage, the real-time measured maximum current in the boost inductor and the value of $T_{\text {d1}}{}^{\text {con}}$ . In the discontinuous mode, it can be set as a variable value relevant to the real-time measured output voltage, the inductance value, the duty cycle, the switching period, the input voltage and the value of $T_{\text {d1}}{}^{\text {con}}$ ( $T_{\text {d2}}{}^{\text {discon}}$ ). The dead-times before the active SiC MOSFET turns on and after the active SiC MOSFET turns off in the continuous and discontinuous mode constitute the self-adaption dead-time, which can be automatically adjusted according to circuit parameters and decrease the loss around the dead-time especially at the high switching frequency. The effectiveness of the proposed self-adaption dead-time setting is proved by the experiment finally, which can reduce the loss by 12.5% in the continuous mode when the output voltage is 400V, the output power is 880W and the switching frequency is 100kHz and can reduce the loss by 12.0% in the discontinuous mode when the output voltage is 400V, the output power is 440W and the switching frequency is 20kHz.

The grid-integrated doubly fed induction generator (DFIG) is required to participate in the frequency regulation of the power system. The supercapacitor energy storage (SES) is capable of enhancing the frequency regulation capability of the DFIG in a coupled manner. The SES is connected to the DC capacitor of the DFIG and provides active power response through the droop control. The dynamic power flow (DPF) model is established to quantify the frequency response of the power system when the DFIG-SES system participates in the frequency regulation. The integration of the SES affects the internal power flow distribution of the DFIG; thus, the detailed model of the DFIG is incorporated into the DPF analysis. Considering the different response speeds of the synchronous generator (SG), the SES, and the DFIG to the frequency regulation, the first-order inertia delay in the governor control of the SG is included in the DPF model. The impact of the delay time constant on the continued operation time of the SES is analyzed. With the same deloading percentage, the output power of the DFIG is adjusted based on a variable droop coefficient scheme to fully utilize its active power reserve. The feasibility and effectiveness of the DFIG-SES scheme to participate in the frequency regulation are analyzed based on the DPF and verified through numerical analysis.

As a large scale of renewable energy generation including wind energy generation is integrated into a power system, the system frequency stability becomes a challenge. The battery energy storage system (BESS) is a better option for enhancing the system frequency stability. This research suggests an improved frequency regulation scheme of the BESS to suppress the maximum frequency deviation and improve the maximum rate of change of the system frequency and the system frequency of the steady state. To this end, the droop control with the input of the system frequency excursions is employed into the controller of the BESS. To improve the frequency-supporting capability and prevent the over-discharging phenomenon, the control coefficient is defined as a proportional function of the instantaneous state of charge of the BESS and excursions of the system frequency. The contributions of the proposed frequency regulation scheme are investigated with various wind power penetration level conditions and disturbances. Results clearly indicate that the proposed frequency regulation scheme of the BESS is able to achieve objectives in terms of enhancing the maximum frequency excursion, the system frequency of the steady state, and the rate of change of the system frequency under various wind power penetration level conditions, initial SOCs, and disturbances.

The doubly-fed induction generators (DFIGs) integrated to the grid through the voltage source converter-high voltage direct current (VSC-HVDC), the cascaded droop control from the system frequency to the DC voltage, then to the active output of the DFIG, was applied to enhance the frequency regulation capability of the power system. The improved dynamic power flow (DPF) model was newly proposed to quantify the frequency response of the coordinated regulation with the inertia of the VSC-HVDC and the DFIGs, and the primary regulation of the synchronous generators (SGs) and the DFIGs. New features of the proposed model include: (i) the SGs’ output in the DPF considering the governor delay, (ii) setting of the virtual inertia of the VSC-HVDC within the DC voltage constraint, and (iii) variable inertia of the DFIGs following changing the kinetic energy of the rotor. The numerical results show the feasibility of the proposed model, and validate the regulation effect and accuracy of the modified inertia of the DFIGs and the maximized virtual inertia of the VSC-HVDC.

Fast and accurate simulation of the outdoor airflow distribution is important for studying urban microclimate. In this paper, two pressure-correction schemes (i.e., NIPC and NSPF) for solving the N-S equation item by item are implemented in OpenFOAM and their differences from the PISO algorithm in simulating the airflow around a single 1:1:2 bluff body are analyzed. The RNG k-ε turbulence model is chosen to study the airflow disturbance, while the second-order discretization scheme of Gauss limitedLinear is used to solve the advection term in the N-S equation. The results show that the NIPC can accurately predict the main airflow characteristics around the bluff body, while the NSPF cannot predict the recirculation region on its top. The two pressure-correction schemes underestimate the TKE distribution on the top and leeward sides of the bluff body when applying the RNG k-ε turbulence model, and the maximum relative error is about 30%. However, they are consistent with the results of the PISO algorithm under the same conditions. The two schemes are about 2.5-3.0 times faster than the PSIO algorithm when run on a CPU, and the NSPF is about 12% faster than the NIPC scheme.

Volumetric measurement of polyacrylamide hydrogel (PAHG) is useful for surgical planning. It is not only a significant factor in the preoperative evaluation of breast augmentation, but may also directly affect the postoperative shape of the breast. The objective of the present study was to evaluate whether magnetic resonance imaging (MRI) is able to provide precise calculations of injected PAHG volumes. MRI scans of ten randomly selected patients were imported to Mimics software. The volumes of PAHG were obtained following the reconstruction of the injected PAHG. In order to assess the precision and observer independency of the technique, the volumes of PAHG were estimated by three plastic surgeons using this method. No significant differences were identified among the PAHG injection volumes calculated by the three observers (P=0.173). The intra-observer correlation coefficient was 0.964, which indicates the precision and feasibility of this method for calculating the volume of PAHG. The use of MRI in combination with Mimics software to calculate PAHG volumes is likely to be of significant clinical benefit in preoperative surgical planning. [ABSTRACT FROM AUTHOR]

An inertial response emulated control strategy of doubly-fed induction generators (DFIGs) is able to arrest their frequency decline following a severe frequency event. Nevertheless, the control coefficient is unchanged, so as to limit the benefit potentiality of improving the inertial response capability for various disturbances and provide less of a benefit for boosting the frequency nadir. This paper addresses an enhanced inertial response emulated control scheme for a DFIG to improve the maximum frequency deviation and maximum rate of change of frequency for various disturbances. To this end, the control coefficient is coupled with the system frequency deviation so as to regulate the control coefficient according to the system frequency deviation (i.e., sizes of the disturbance). Results clearly indicate that the proposed inertial response emulated control strategy provides better performance in terms of improving the maximum rate of change of frequency and maximum frequency deviation under various sizes of disturbance and random wind speed conditions.

With the fast growth in the penetration of wind power, doubly fed induction generators (DFIGs) are recommended for their ability to enforce grid codes that provide inertial control services by releasing rotational energy. However, after supporting the system frequency, a second frequency drop (SFD) is prone to occurring to regain the rotor speed caused by the sudden reduction in output. In this article, we propose a torque limit-based fast stepwise inertial control scheme of a DFIG using a piecewise reference function for reducing the SFD while preserving the frequency nadir (FN) with less rotor energy released. To achieve the first objective, the power reference increases to the torque limit and then decays with the rotor speed toward the preset operating point. To achieve the second objective, the power reference smoothly lessens over time based on the exponential function. The performance of the proposed stepwise inertial control strategy was studied under various scenarios, including constant wind speed and ramp down wind speed conditions. The test results demonstrated that the frequency stability is preserved during the frequency support phase, while the second frequency drop and mechanical stress on the wind turbine reduce during the rotor speed restoration phase when the DFIG implements the proposed stepwise inertial control scheme.

Voltage source (VS) control based on inertia synchronization is a novel phase lock loop (PLL)-less autonomous grid-synchronization control strategy suitable for the permanent magnet synchronous generator (PMSG)-based wind turbine. It can autonomously sense grid frequency fluctuations by adopting the dynamics of DC-link capacitor, and it has the advantage of stable operation in an extremely weak grid. This paper further studies the low-voltage ride-through (LVRT) of the PMSG-based wind turbine under the VS control, and presents a wind turbine structure with the additional energy storage battery on the DC side, which not only improves its LVRT capability but also enables the wind turbine to participate in the grid primary frequency regulation. The transient characteristics of VS-controlled wind turbines after the occurrence of the short-circuit fault are analyzed, and a current suppression strategy via switching the virtual resistor in the control loop of the grid-side converter (GCS) is presented. Through coordination with the energy storage battery, the LVRT of the PMSG-based wind turbine is realized, which has the advantage of withstanding a long-time short-circuit fault. Finally, based on the PSCAD/EMTDC simulation platform, the feasibility of the control strategy and the correctness of the theoretical analysis are verified.