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Brown adipose tissue (BAT) activity contributes to cardiovascular health by its energy-dissipating capacity but how BAT modulates vascular function and atherosclerosis through endocrine mechanisms remains poorly understood. Here we show that BAT-derived neuregulin-4 (Nrg4) ameliorates atherosclerosis in mice. BAT-specific Nrg4 deficiency accelerates vascular inflammation and adhesion responses, endothelial dysfunction and apoptosis and atherosclerosis in male mice. BAT-specific Nrg4 restoration alleviates vascular inflammation and adhesion responses, attenuates leukocyte homing and reduces endothelial injury and atherosclerosis in male mice. In endothelial cells, Nrg4 decreases apoptosis, inflammation and adhesion responses induced by oxidized low-density lipoprotein. Mechanistically, protein kinase B (Akt)–nuclear factor-κB signaling is involved in the beneficial effects of Nrg4 on the endothelium. Taken together, the results reveal Nrg4 as a potential cross-talk factor between BAT and arteries that may serve as a target for atherosclerosis.

Whether bone marrow regulates bone metabolism through endocrine and paracrine mechanism remains largely unknown. Here, we found that (i) myeloid cell-specific myeloid-derived growth factor (MYDGF) deficiency decreased bone mass and bone strength in young and aged mice; (ii) myeloid cell-specific MYDGF restoration prevented decreases in bone mass and bone strength in MYDGF knockout mice; moreover, myeloid cell-derived MYDGF improved the progress of bone defects healing, prevented ovariectomy (OVX)-induced bone loss and age-related osteoporosis; (iii) MYDGF inhibited osteoclastogenesis and promoted osteoblast differentiation in vivo and in vitro; and (iv) PKCβ-NF-κB and MAPK1/3-STAT3 pathways were involved in the regulation of MYDGF on bone metabolism. Thus, we concluded that myeloid cell-derived MYDGF is a positive regulator of bone homeostasis by inhibiting bone resorption and promoting bone formation. MYDGF may become a potential novel therapeutic drug for osteoporosis, and bone marrow may become a potential therapeutic target for bone metabolic disorders.

The pressure drop characteristics of supercritical carbon dioxide (S-CO2) are experimentally studied in horizontal rectangular microchannels with hydraulic diameters of 1 and 2 mm, which are used in printed circuit heat exchangers. The operating conditions include an operating pressure of 9–12 MPa, a mass flux of 290–1200 kg/m2 s, and a heat flux of 25–50 kW/m2. The four contributors to pressure drop in the S-CO2 microchannels were investigated. The results indicate that the total pressure drop decreases for lower operating pressures and mass fluxes, whereas the heat flux has little impact. The most significant contributor to the total pressure drop is the frictional pressure drop. The accelerational pressure drop increases with the heat flux. Eventually, a new frictional resistance correlation is proposed where the microchannel size and thermophysical property variations are considered.

Whether the widespread anti-osteoporosis treatments in postmenopausal women also benefit the change of body composition (lean body mass [LBM] and body fat mass [FM]) remains controversial. In order to solve this issue and find out the most effective treatment, we conducted this meta-analysis.We searched the literature, via PubMed, Embase, Scopus, Web of Science, and Cochrane to screen citations from inception to March 26, 2022, for inclusion in this study. Only clinical trials that used anti-osteoporosis treatments in postmenopausal women and displayed the alteration of body composition were included. Stata 14.0 was used for the meta-analysis.Our meta-analysis results presented that: compared with placebo, hormone replacement therapy (HRT) was associated with increased LBM (standardized mean differences [SMD] = 0.32, 95% confidence interval [CI] = 0.02-0.61) and reduced FM (SMD = -0.30, 95% CI = -0.51 to -0.09) in postmenopausal women. Compared with placebo, physical exercise training showed an effect of decreasing FM (SMD = -0.66, 95% CI = -0.94 to -0.38) but not significant influence LBM (SMD = 1.31, 95% CI = -0.29 to 2.91). The network meta-analysis of our study showed that oral estrogen and progestogen plus exercise (OEPE) treatment might be the most effective anti-osteoporosis treatment (surface under the cumulative ranking curve 99.9) to reduce FM in postmenopausal women.anti-osteoporosis treatments, especially HRT, affect body composition. Furthermore, the combination of HRT and exercise training are the most effective treatment to reduce FM while maintaining LBM.

The organic Rankine cycle (ORC) is a promising engine waste heat recovery (WHR) technology. However, with a change in the engine operating conditions, the choice of ORC-WHR system operating parameters have great influence on system performance. Therefore, this study investigated the changing law of ORC-WHR system operating parameters optimal value and the sensitivity of the system to the operating parameters under eight different engine operating conditions. That is, the research on operating parameters matching characteristic. The two key operating parameters selected were expander speed (Sexp_shaft) and superheat degree (SD). The performance indexes of the system included expander shaft efficiency (ηexp_shaft), thermal efficiency (ηth), evaporator heat exchange (Qeva), expander output work (Wexp_shaft), pump work consumption (Wpump), and net power output (Wnet). The results showed that Sexp_shaft was the most significant parameter affecting the system performance. As engine load increased from 1000 rpm, 300 Nm to 1350 rpm, 650 Nm, the best Sexp_shaft of Wnet increased from 1200 to 1600 rpm. As the engine load increased, the sensitivity of the system to Sexp_shaft and SD gradually decreased. The influence of the Sexp_shaft on Wnet decreased from 90.28% to 7.78%. The effect of the SD on the Qeva decreased from 11.26% to 5.16%.

Exhaust waste heat recovery technology based on power cycles requires high efficiency, low flow resistance, and a compact structure for exhaust gas heat exchangers. It is a huge challenge for traditional heat exchangers, such as double tube or shell and tube heat exchangers. A printed circuit heat exchanger (PCHE), which is a compact heat exchanger, has not been used in the heat exchange process between the exhaust gas and supercritical CO2. Focusing on this application, a novel design concept of PCHE based on a comprehensive performance index is proposed, which fully considers the differences in physical properties and working conditions between the exhaust gas side and the CO2 side. A series of experiments were carried out in a CO2-based transcritical power cycle system. The experimental test results show that the PCHE with a novel structure is stable and feasible. To further optimise the PCHE, a numerical analysis of different structures was conducted. The calculation results show that the comprehensive performance of the PCHE with an optimised structure was improved by 11.92%. This research shows that PCHE has great potential for achieving a compact design with excellent performance, especially for use in engine waste heat recovery.

CO2-based mixture is a potential working fluid choice of combined cooling and power cycle (CCP) due to its superior thermodynamic performances and the removal of the limit of CO2 critical temperature. This study proposes a CCP system using CO2-based mixtures, loaded on a refrigerated truck, to realize multi-mode transformations for diverse cooling and power demands. The components of mixtures are strictly screened and key parameter analyses and optimization in terms of energy, exergy, adjustability, and economic performance are conducted to find the general laws and the best composition of the mixtures. The results show CO2-based mixtures have better energy-saving potential, adaptability, adjustability, and compactness than CO2. By comparison, CO2/R32 is recommended for superior output capacity, lower operation parameters, remarkable adjustability, and cheaper investment cost. CCP using CO2/R32 can maximally achieve 6.9% power enhancement or 5.9 times cooling enhancement relative to the refrigerated truck using a stand-alone refrigerator, and 19% power increase or 80% cooling increase relative to the CO2 system. It can realize smooth and steady mode transformation to achieve complex and diverse allocation of refrigeration and power in actual operation.

To ameliorate the adaptability of the ship waste heat recovery system (SWHRS) to the variable energy demand, this paper proposes a CO2-mixture-based SWHRS providing refrigerating output as well as adjustable heating and electrical output. The adjustability deriving from mixture composition regulation profits from liquid separation condensers. A scientific vessel YUKUN is selected as the recovery target, the energy demand characteristics of which in different seasons (spring/autumn, summer, and winter) and conditions (sailing and berthing) are exploited to determine six operating modes. Well-designed configurations of SWHRS’s subsystems with different energy exportation emphases improve the matching of SWHRS to changes in energy demand. Moreover, composition adjustment corresponding to various energy requirements further modifies the energy conversion tendency of waste heat to heating or electrical energy desired by the target ship. Comparative research demonstrates that SWHRS possesses certain superiority over the non-adjustable system due to the regulation of mixture composition corresponding to variation in energy requirement. Thus, the SWHRS can reduce the fuel consumption rate by 4.9% to 17.2% compared to the original waste heat recovery system in YUKUN at different modes. Based on actual operating data, the SWHRS can realize a decline of 10.3% in the annual fuel consumption rate. Hence, a fuel charge of 245 000 USD could be saved for YUKUN equipped with SWHRS for one year.

The integrated design of gas heat exchanger and after-treatment unit can reduce the size and weight of the engine waste heat recovery system, releasing the back pressure of exhaust gas and enhancing net benefit of the waste heat recovery system. In this study, we propose a silencing heat exchanger that integrates an exhaust heat exchanger with an impedance composite muffler in the post-treatment system, using metal foam material instead of the sound absorbing material in the impedance composite muffler. By adapting ANSYS Fluent and LMS Virtual.Lab, thermal simulation and acoustic simulation of the silencing heat exchanger were realized, and comparative analysis of the modified structure and the basic structure was carried out. The modified silencing heat exchanger was then designed and fabricated, and the thermal and acoustic performance were tested. The results show that the modified silencing heat exchanger can achieve improved heat transfer and flow performance, and more uniform temperature distribution at the hot side, simultaneously resulting in an 8.4% reduction in exhaust pressure drop. Even more, the improvement of silence effect in the middle and high frequency band is fairly obvious, and the overall transmission loss is 44.4% higher than that of the basic structure.