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The supercritical CO2 Brayton cycle has potential to be used in electricity generation occasions with its advantages of high efficiency and compact structure. Focusing on a so-called self-condensing CO2 transcritical power cycle, a model was established and four different layouts of heat recuperation process were analyzed, a without-recuperation cycle, a post-recuperation cycle, a pre-recuperation cycle and a re-recuperation cycle. The results showed that the internal normal cycle's share of the whole cycle increases with increasing the cooling pressure and decreasing the final cooled temperature. Heat load in the supercritical heater decreases with increasing the cooling pressure. From perspective of performance, the re-recuperation cycle and the pre-recuperation cycle have similar thermal efficiency which is much higher than other two layouts. Both thermal efficiency and net power output have a maximum value with the cooling pressure, except in the condition with the final cooled temperature of 31°C. Considering both the complexity and the economy, the pre-recuperation cycle is more applicable than the other options. Under 35°C of the final cooled temperature, the thermal efficiency of the pre-recuperation cycle reaches the peak 0.34 with the cooling pressure of 8.4 MPa and the maximum net power output is 2355.24 kW at 8.2 MPa of the cooling pressure. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) semiconductors with suitable band gaps, high carrier mobility, and environmental stability are crucial for applications in the next generation of electronics and optoelectronics. However, current candidate materials each have one or more issues. In this work, two novel C3N2 monolayers, P-C3N2 and I-C3N2 are proposed by first-principles calculations. Both structures have demonstrated excellent dynamical and mechanical stability, with thermal stability approaching 3000 K. Importantly, P-C3N2 shows a distinct advantage in formation energy compared to currently synthesized 2D carbon nitride materials, indicating its potential for experimental synthesis. Electronic structure calculations reveal that both P-C3N2 and I-C3N2 are intrinsic semiconductors with moderate band gaps of 2.19 and 1.81 eV, respectively. Additionally, both C3N2 monolayers display high absorption coefficients up to 105 cm−1, with P-C3N2 showing significant absorption capabilities in the visible light region. Remarkably, P-C3N2 possesses an ultra-high carrier mobility of up to 104 cm2 V−1 s−1. These findings provide theoretical insights and candidates for future applications in the electronics and optoelectronics fields. [ABSTRACT FROM AUTHOR]

Background China is currently making efforts to transform the current hospital-centric service delivery system to people-centred primary health care (PHC)-based delivery system, with service delivery organized around the health needs and expectations of people. To help direct China's PHC reform efforts, a profile of high-quality PHC from the public's perspective is required. Objectives To profile high-quality PHC from the perspective of the Chinese public. Methods Semistructured interviews were conducted in 6 provinces (Henan, Shandong, Zhejiang, Shaanxi, Shanxi, and Heilongjiang) in China. In total, 58 interviewees completed the recorded interview. For transcription, trained research assistant listened to the recording of the interviews, summarizing each 30-s segment in English. Next, thematic analysis was performed on the narrative summaries to identify thematic families. Results Seven themes and 16 subthemes were generated from the analysis of our interview data. In order of their frequency, the interviewees expressed a high expectation for interpersonal communication and technical quality; followed by access, comprehensive care, cost, continuity, and coordination. Conclusions Using qualitative data from 6 provinces in China, knowledge was generated to reveal the public's views and expectations for high-quality PHC. Our results confirm the urgent need for quality improvement efforts to improve patient experience and technical quality. The government also needs to further improve the delivery system and medical training programme to better meet public expectation in these areas, especially in establishing an innovative integrated primary care model, and strengthening interpersonal and clinical competency training for family doctors. [ABSTRACT FROM AUTHOR]