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Supercritical CO2 Brayton cycle has high efficiency, compactness, and excellent power generation potential. In the design of the cycle, some parameters, such as recuperator pinch point temperature difference (ΔTrec,pp), turbine inlet temperature (Ttur,in), and maximum cycle pressure (pmax), are often preset without optimization. Furthermore, different preferences on efficiency and cost tradeoff can significantly affect the optimal design of the cycle, and the influence of different parameters on the design condition and the optimum cycle configuration becomes unclear as the preference changes. In this study, different preferences on efficiency and cost tradeoff are considered, and the effects of cycle configuration and optimization parameter addition on the tradeoff are investigated. In addition, four configurations under different preferences on tradeoff are recommended. Results show that the design condition parameters ΔTrec,pp decrease and Ttur,in and pmax increase as the preference of thermal efficiency (Wth) increases. Different optimized parameters affect the results of the design point and cycle performance. In addition, the simple recuperative cycle and reheating cycle are recommended when low cycle initial cost dominates (Wth 0.701). The decision maker can select appropriate configuration according to specific preferences.

Background: Hepatocellular Carcinoma (HCC) is one of the most common malignant tumors with high mortality. Fatty acid metabolism is associated with the development and treatment of HCC. This study aimed to build a fatty acid metabolism-related gene model to evaluate the prognosis of HCC patients and provide guidance for individualized treatment.Methods: RNA-sequencing data of HCC from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) database were extracted as the training set and validation set. Fatty acid metabolism-related genes predictive signature was built using univariate and least absolute shrinkage and selection operator (LASSO) Cox regression analyses. The predictive value of prognostic model was evaluated by Kaplan-Meier (K-M) curves, ROC curves, univariate and multivariate Cox regression. In addition, the immune infiltration and drug sensitivity were also explored.Results: A twelve-gene fatty acid metabolism-related risk signature was constructed. Patients were divided into low-risk and high-risk groups according to risk scores. High-risk patients with the higher risk scores had a poor prognosis. Then, univariate and multivariate Cox regression showed that risk score was an independent risk factor for the overall survival of HCC. K-M and ROC curves further verified the predictive value of the signature. Besides, nomograms were drawn and exhibited the good performance in the prognostic prediction. Finally, the immune cell infiltration and sensitivity to chemotherapy drugs exhibited a correlation with different risk levels.Conclusion: This novel fatty acid metabolism-related gene predictive signature may be useful for improving prognosis evaluation and individualized treatment for HCC patients.

Hepatocellular Carcinoma (HCC) is a highly heterogeneous malignant tumor, and its prognostic prediction is extremely challenging. Ferroptosis is a cell mechanism dependent on iron, which is very significant for HCC development. Long non-coding RNA (lncRNA) is also linked to HCC progression. This work aimed to establish a prognosis risk model for HCC and to discover a possible biomarker and therapeutic target.The Cancer Genome Atlas (TCGA) database was used to obtain RNA-seq transcriptome data and clinic information of HCC patients. Firstly, univariate Cox was utilized to identify 66 prognostic ferroptosis-related lncRNAs. Then, the identified lncRNAs were further included in the multivariate Cox analysis to construct the prognostic model. Eventually, we performed quantitative polymerase chain reaction (q-PCR) to validate the risk model.We established a prognostic seventeen-ferroptosis-related lncRNA signature model. The signature could categorize patients into two risk subgroups, with the low-risk subgroup associated with a better prognosis. Additionally, the area under the curve (AUC) of the lncRNAs signature was 0.801, indicating their reliability in forecasting HCC prognosis. Risk score was an independent prognostic factor by regression analyses. Gene set enrichment analysis (GSEA) analyses demonstrated a remarkable enrichment of cancer-related and immune-related pathways in the high-risk group. Besides, the immune status was decreased in the high-risk group. Eventually, three prognostic lncRNAs were validated in human HCCLM3 cell lines.The risk model based on seventeen-ferroptosis-related lncRNA has significant prognostic value for HCC and may be therapeutic targets associated with ferroptosis in clinical ways.

Background: The comparison between microbiota of cecal and colonic mucosa in irritable bowel syndrome (IBS) was rarely studied. In addition, enterochromaffin (EC) cell had interaction with IBS. The aim of this study was to investigate the relationship among gut microbiota, EC cell and diarrhea-predominant IBS (IBS-D) symptoms in cecum and descending colon. Methods: Biopsies from cecum and descending colon were taken during endoscopy withdrawal. We assessed EC cell numbers, expression of tryptophan hydroxylase 1 (TPH1) and microbial diversity.Results: Total of 22 IBS-D patients and 22 health controls (HCs) were enrolled. The relative abundance of Ruminococcus_torques_group (4.91% vs. 2.20%, P = 0.04763) of cecum increased in IBS-D, while Raoultella (1.58% vs. 1.76%, P = 0.03117) and Fusobacterium (0.12% vs. 1.66%, P = 0.01892) were less abundant. In descending colon, the relative abundances of Ruminococcus_torques_group (5.94% vs. 2.29%, P = 0.04183) and Dorea (2.68% vs. 1.14%, P = 0.04962) of IBS-D increased but Fusobacterium (1.52% vs. 1.89%, P = 0.0345) decreased. EC cells number in cecum of IBS-D was higher than that in HCs and TPH1 level of IBS-D was higher than that of HCs in cecum and descending colon. Correlation analysis showed that Ruminococcus_torques_group were positively associated with HAM-A (r= 0.66, P = 0.004), HAM-D (r= 0.61, P = 0.009), EC cell number (r= 0.49, P = 0.047), IBS-SSS (r= 0.65, P = 0.004), Degree of Abdominal Pain (r = 0.63, P = 0.007), Frequency of Abdominal Pain (r = 0.63, P = 0.007), Frequency of Defecation (r = 0.60, P = 0.011). The abundance of Dorea were positively associated with EC cell number (r = 0.57, P = 0.018), IBS-SSS (r = 0.52, P = 0.034), HAM-A (r = 0.72, P = 0.001), HAM-D (r = 0.59, P = 0.012), Frequency of Abdominal Pain (r = 0.67, P = 0.003).Conclusions: EC cells number increased in IBS-D patients and the expression of TPH1 was higher than HCs. In addition, our results suggested Ruminococcus_torques_group and Dorea may be targets for treatment of IBS-D but still need further studies.

Solar organic Rankine cycle (SORC) is a promising approach for solar energy utilization under low and moderate temperatures due to low investment and small-to-medium scale. The stable output of the SORC system under variable solar irradiation conditions is necessary to weaken the impact on the power grid and provide a base load. A novel operating mode was designed to obtain the stable output of 1 MWe for a SORC system operated under variable solar irradiation for 1 day. The parabolic trough collector was selected for solar heat reception, and a two-tank direct thermal storage unit was used for heat storage. Given the variations in solar irradiation, the mass flow rate of the heat transfer fluid (HTF) in the solar collectors was adjusted to guarantee a constant HTF inlet temperature for the ORC unit, and the mass flow rate of the HTF from the hot tank to the ORC unit was kept constant. Thus, the SORC system could operate under stable conditions. Four organic working fluids and two cycle types were subjected to thermodynamic analysis and parametric optimization. Results show that as the HTF inlet temperature increases, the optimal efficiency of system with non-recuperative cycle and toluene increases, whereas those of systems with non-recuperative cycles and cyclohexane, hexamethyldisiloxane, and pentane as working fluids first increase and then remain constant. The increment in the superheat degree increases the efficiency of the system with recuperation. By contrast, the system with non-recuperation demonstrates the maximum system efficiency in the absence of or at a low superheat degree. The maximum system efficiency reaches 17.9%. The system efficiency of this novel operating mode is 4.2% higher than that of an unstable output operating mode when operated for 1 day.

Background Accumulating evidence supports the pivotal role of intestinal flora in irritable bowel syndrome (IBS). Serotonin synthesis by enterochromaffin (EC) cells is influenced by the gut microbiota and has been reported to have an interaction with IBS. The comparison between the microbiota of the caecal and colonic mucosa in IBS has rarely been studied. The aim of this study was to investigate the relationship between the gut microbiota, EC cells in caecum and descending colon, and diarrhoea-predominant IBS (IBS-D) symptoms. Results A total of 22 IBS-D patients and 22 healthy controls (HCs) were enrolled in our study. Hamilton anxiety (HAM-A) and Hamilton depression (HAM-D) grades increased significantly in IBS-D patients. In addition, the frequency of defecation in IBS-D patients was higher than that in HCs. Among the preponderant bacterial genera, the relative abundance of the Ruminococcus_torques_ group increased in IBS-D patients in caecum samples while Raoultella and Fusobacterium were less abundant. In the descending colon, the abundance of the Ruminococcus_torques_group and Dorea increased in IBS-D patients and Fusobacterium decreased. No difference was observed between the descending colon and caecum in regards to the mucosal-associated microbiota. The number of EC cells in the caecum of IBS-D patients was higher than in HCs and the expression of TPH1 was higher in IBS-D patients both in the caecum and in the descending colon both at the mRNA and protein level. Correlation analysis showed that the Ruminococcus_torques_group was positively associated with HAM-A, HAM-D, EC cell number, IBS-SSS, degree of abdominal pain, frequency of abdominal pain and frequency of defecation. The abundance of Dorea was positively associated with EC cell number, IBS-SSS, HAM-A, HAM-D and frequency of abdominal pain. Conclusions EC cell numbers increased in IBS-D patients and the expression of TPH1 was higher than in HCs. The Ruminococcus torques group and Dorea furthermore seem like promising targets for future research into the treatment of IBS-D patients.

The supercritical CO2 Brayton cycle integrated with a solar power tower system has the advantages of high efficiency, compact cycle structure, strong scalability, and great power generation potential, which can positively deal with the energy crisis and global warming. The selection and optimization of design points are very important for actual operating situations. In this paper, the thermodynamic and economic models of the 10 MWe supercritical CO2 Brayton cycle for application in solar power tower system are established. Multi-objective optimizations of the simple recuperative cycle, reheating cycle, and recompression cycle at different compressor inlet temperature are completed. The thermal efficiency and the levelized energy cost are selected as the fitness functions. The ranges of the optimal compressor inlet pressure and reheating pressure on the Pareto frontier are analyzed. Finally, multiobjective optimizations and analysis of the supercritical CO2 Brayton cycle at different ambient temperature are carried out. This paper investigates the influence of the compressor inlet temperature and ambient temperature on the thermal efficiency and economic performance of the supercritical CO2 Brayton cycle.

A hybrid renewable energy system, including photovoltaic (PV) plant, wind farm, concentrated solar power (CSP) plant, battery, electric heater, and bidirectional inverter, is proposed. The optimal combination of power plants and energy storage devices, and their optimal capacities are obtained by the multi-objective optimization algorithm. A superior operation strategy of the system, which consists of multiple energy storage technologies and flexible power supplies, is proposed. Results show that the PV plant with an inverter can generate power at the lowest cost but with poor reliability. The combination of the CSP plant and PV plant is an effective way to improve power generation reliability economically. When low investment costs of PV plant, battery, and inverter are adopted, the battery is preferentially integrated into PV plant to reduce the loss of power supply probability (LPSP) to a certain level. But it still cannot meet the high power generation reliability requirements. The CSP plant is still an essential technology to further significantly reduce LPSP with good economic performance. The operation strategy in which the power cycle takes precedence over the battery to supplement the power shortage is recommended. The levelized cost of energy (LCOE) of the system with power cycle output priority is 8.36% lower than that of the system with battery output priority when the LPSP is 1.34%.

This study proposes a novel design optimization method for the solar power tower (SPT) system with a supercritical CO2 (S-CO2) Brayton cycle. The design conditions are determined based on annual off-design performance. The fluctuating solar irradiation and ambient temperature in different locations, and various power demand scenarios, including stable, light industry, and hybrid PV + CSP system types, are considered. The parameters of solar multiple (SM), thermal energy storage (TES) capacity, and designed compressor inlet temperature are simultaneously optimized by the multi-objective optimization algorithm. Results show that compared with the conventional design method, the novel design method can improve the maximum load cover factor by 6.38% under stable power demand and reduce the levelized cost of energy by 5.62% with a load cover factor of 0.9 under light industry power demand in Daggett. The optimal design conditions and actual operating performance are significantly affected by the weather conditions, power demand scenarios, and optimization objectives. For most cases to increase load cover factor in the most economical way, increasing SM and TES capacity coordinately is preferred to be implemented first, followed by increasing designed compressor inlet temperature. Whereas, for cases with a high frequency of simultaneous high ambient temperature and high power demand, increasing designed compressor inlet temperature will be advanced to the same priority as increasing SM and TES capacity.

In this work, the load matching and techno-economic performance of concentrated solar power (CSP) plants based on four supercritical CO2 (S–CO2) Brayton cycles, different solar multiple (SM) and thermal energy storage (TES) capacities are analyzed in a CSP-PV-wind hybrid system. The performance of CSP plant for meeting varied power demand in hybrid system and stable power demand are compared. Results show the lowest levelized cost of energy (LCOE) of CSP plant based on partial-cooling cycle under load following scenarios in hybrid system is 32.1% higher than that under stable output scenarios. The optimal SM to achieve the lowest LCOE under stable output scenarios is much larger than that under load following scenarios in hybrid system. As SM and TES capacity increase, the capacity factor of hybrid system increases and can even exceed 90%, which represents that CSP plant can cooperate well with PV and wind plants to provide stable base loads. The LCOE of CSP plant first decreases and then increases with the increase of SM and TES capacities. The CSP plant based on partial-cooling cycle has the best economic performance, and achieves the lowest LCOE of 0.2169 $/kWh with SM of 2.4 and TES capacity of 20 h.

The system that integrates solar power tower, molten salt thermal storage, and supercritical CO2 (S-CO2) Brayton cycle has emerged as a promising technology to provide a dispatchable power output following the power demand. Studying the part-load performance of the S-CO2 Brayton cycle is crucial to achieve an efficient system operation during power load adjustment. In this work, the performance of four typical S-CO2 Brayton cycles including simple recuperative cycle, reheating cycle, recompression cycle, and intercooling cycle are analyzed and compared under part-load conditions. The optimal cycle layouts under different power demand scenarios are revealed. Results show that the reheating cycle achieves higher efficiency than the simple recuperative cycle, and the recompression cycle and intercooling cycle perform better than the reheating cycle under part-load conditions. However, the intercooling cycle is more efficient than the recompression cycle only when the load exceeds 60%. Given that the relative reduction in the reheating cycle efficiency is minimal as the load decreases, this cycle shows the best response to the requirement of wide-range load adjustment. When the ratio of the actual total electricity generation to the maximum total electricity generation in a certain period is lower than 62.5%, the recompression cycle performs better. When this ratio is higher than 68.3%, the intercooling cycle performs better. In general, the efficiency of intercooling cycle is not significantly improved compared with that of the recompression cycle under the load-following scenarios.

This work focuses on the off-design performance of the system integrated a simple recuperative supercritical CO2 Brayton cycle, solar power tower, and thermal energy storage (TES). The system design parameters are obtained first; then, the off-design performance of power cycle and solar receiver are analyzed from the perspective of influencing factors; finally, the daily performance simulations of overall system are conducted. This work is aimed at analyzing the system performance under more realistic conditions, and clarifying the influence mechanism between parameters of solar field, TES and power cycle under off-design conditions. Results show that the increase in ambient temperature and input energy to the receiver, and the decrease in molten salt temperature from the cold tank are beneficial to improve the solar receiver efficiency. As the power demand deviates farther from design value, the temperature of molten salt at the heater outlet is higher, which leads to lower solar receiver efficiency. On the summer solstice, the system operates continuously for 24 h with 100% electricity powered by solar energy and 17.8% daily averaged solar-to-electricity efficiency. On the winter solstice, the system operates continuously for 17 h with 72.6% electricity powered by solar energy and 17.1% daily averaged solar-to-electricity efficiency.

Organic Rankine cycle (ORC) is a widely used technology to generate power from renewable energy and waste heat. Dual-pressure evaporation cycle holds immense potential to be used in ORC systems because it can remarkably increase the heat-work conversion efficiency and improve the adaptability of ORC to heat sources with various characteristics. This study compared the thermodynamic performance of single-pressure and dual-pressure evaporation ORCs for heat sources with outlet temperature limit, based on five organic fluids. Effects of the heat source outlet temperature limit on the characteristics of dual-pressure evaporation ORC system were also discussed. Results show that the dual-pressure evaporation cycle can substantially increase the net power output by increasing system efficiency, and is beneficial to reduce the charge volume of organic fluid in the system, compared to the single-pressure evaporation cycle. The increments in net power output of dual-pressure evaporation cycle over the single-pressure evaporation cycle can be 4.9%, 8.3%, 10.8%, 12.8%, and 14.0% at most for R227ea, R1234ze(E), R600a, R245fa, and R601a, respectively. While, compared to heat sources without outlet temperature limit, the increment in net power output of dual-pressure evaporation cycle is remarkably lower for heat sources with outlet temperature limit.