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Excessive energy requirement for the cryogenic condition is still the challenge for the current cryogenic CO2 capture system. In this work, the capture performance is investigated for the aim of en...

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.

Osteoarthritis (OA) is characterized by chondrocyte apoptosis and increased degradation of type II collagen. Inflammation is one of the major risk factors involved in the pathophysiology of OA. Neuregulin 4 (Nrg4) plays a protective role in a variety of low-level inflammatory diseases, such as non-alcoholic fatty liver disease, inflammatory bowel disease, or type 2 diabetes mellitus. Here we found that (1) Nrg4 deficiency aggravated the destruction and inflammation of articular cartilage and the apoptosis of chondrocytes in vivo. (2) Nrg4 restoration reversed these changes in vivo. (3) Murine recombinant Nrg4 (rNrg4) suppressed inflammation and apoptosis of chondrocytes and decreased the degradation of extracellular matrix in vitro. (4) Mechanistically, the mitogen-activated protein kinase/c-jun N-terminal kinase (MAPK/JNK) signaling pathway may be involved in the regulation of Nrg4 in the pathophysiology of OA. Therefore, we concluded that Nrg4 alleviated the progression of OA by inhibiting the inflammation, protecting against apoptosis of chondrocyte, and decreasing the degradation of extracellular matrix in a manner involving MAPK/JNK signaling.

In intelligent transportation systems, there are many tasks that rely on the detection of road congestion, such as traffic signal scheduling and traffic accident detection. As traditional methods for traffic congestion detection are difficult to use, expensive, and may cause damage to the road surface, this paper presents a method for road congestion detection that is based on multidimensional visual features and a convolutional neural network (CNN). This method first detects the density of foreground objects by using a gray-level co-occurrence matrix; second, the speed of moving objects is detected by using the Lucas–Kanade optical flow with pyramid implementation. Third, a Gaussian mixture model is used to model the background, and the CNN is then used to accurately detect the final foreground from the candidate foregrounds. Finally, the proposed method performs road congestion detection in terms of a multidimensional feature space, including traffic density, traffic velocity, road occupancy, and traffic flow. Furthermore, we propose an information entropy method using a histogram of optical flow to enhance the accuracy and reliability of road congestion detection. Simulation results via quantitative and qualitative assessment indicate that the proposed method is able to significantly outperform the state-of-the-art road-traffic congestion detection methods due to the fusion of multidimensional features using the CNN.

For engine waste heat recovery, CO2-based Transcritical Rankine Cycle (CTRC) system with preheating process has a strong capability of combining exhaust gas and engine coolant, thereby leading to improvement of output, efficiency improvement and the reduction in cooling load reduction. In previous researches, all the benefits were achieved and investigated mainly under ideal and stable engine conditions in previous researches. But in this study, various engine conditions were considered for a preheated CTRC test bench, namely starting and ‘warm up’ condition, stopping and idling condition, restarting condition and random condition. After system parameters (e.g. pressure, temperature) were measured, heat absorption quantity was calculated, and meanwhile net power output and thermal efficiency were estimated. The results show that the preheating process can improve the dynamic performance of the CTRC at various engine conditions. Firstly, the preheating process is beneficial for continuous output capacity and safe operation of CTRC. Besides, the preheating process also can avoid the sudden rise in the expansion inlet pressure under the stopping condition of engine, and meanwhile it plays an important energy supplement role in the random conditions of the engine, resulting in the cross change in the waste heat absorption from engine coolant and exhaust gas.

CO2-based Transcritical Rankine Cycle (CTRC) system has attracted more and more attention for exhaust gas recovery currently due to CO2's environmental and stable performance, as well as the miniaturization potential of components. Among the CTRC researches, parameters analysis is an eternal theme, and turbine inlet pressure and temperature are the focus. In real operation, the temperature is mainly influenced by pump speed. In this study, various operating pressure and various pump speed of a CTRC test bench were set for a parameter analysis. Two configurations were considered at a constant engine condition, basic CTRC (B-CTRC) and regenerated CTRC (R-CTRC). After measuring parameters (e.g. pressure, temperature, mass flow rate), heat absorption quantity was calculated, while net power output, thermal efficiency, exergy efficiency were estimated. Results showed that the pressure ratio had significantly positive impact on the CTRC performance. And the law for the effect of mass flow rate was not obvious. The R-CTRC can realize 42.4%, 71% and 48.9% improvement of net power output, thermal efficiency and exergy efficiency relative to the B-CTRC. After the parameter analysis, the optimal condition based on the maximum net power output was predicted by the regression of experimental data.

Great energy conservation potential has been found in engine waste heat recovery, and CO2 transcritical power cycle (CTPC) driven by internal combustion engines has been recognized a promising technological path. Traditional recuperative configuration leads to an increase in thermal efficiency but also has an impact on engine exhaust utilization. Hence, based on the CTPC layout with a recuperator, a splitting design is proposed with an additional heater to reduce the irreversibility from the engine exhaust. Experimental investigation was conducted to reveal the splitting performances compared with the basic recuperative layout. Results showed that the predicted net generated power could be increased by 54.8% from 5.4 kW to 8.4 kW in maximum. The engine exhaust utilization could be improved with a lower exhaust outlet temperature. It should also be noted that the thermal efficiency was also improved by 47.5% compared with the baseline although a higher heat absorption was found in the splitting layout.

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.