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Introduction High altitude polycythemia (HAPC) is a common chronic disease at high altitudes. It is characterized by excessive erythrocytosis (≥190 g·L-1 in females or ≥210 g·L-1 in males). HAPC severely jeopardizes the health status of plateau dwellers. The Qinghai-Tibet plateau, with an elevation above 4000 m, is the highest plateau in the world. Both Han and Tibetan populations residing there face the threat of HAPC. Therapeutic erythrocytapheresis (TE) was introduced to Tibet as an alternative to phlebotomy in 2015. Methods In this study, we retrospectively analyzed 155 patients with HAPC treated with TE in Tibet. Routine blood testing values before and after TE were compared to evaluate treatment efficacy. The efficiency rate, defined as the rate of increase in red blood cell depletion attained by TE compared with 450 mL whole blood phlebotomy, was calculated using whole blood volume and hematocrit before and after treatment and used to identify patients who maintained a normal hemoglobin level in the year after the TE procedure. Results On average, TE reduced red blood cell levels by 1.5×1012·L-1, hemoglobin concentration by 52 g·L-1, and hematocrit by 14% (P Conclusions TE is a feasible therapeutic method to treat HAPC on the Qinghai-Tibet plateau. The efficiency rate is a useful tool to predict the expected interval between TE procedures.

In this paper, a novel axial slot casing treatment design is introduced via optimization to improve the stall margin of the compressor with minimal efficiency loss. Besides the conventional design parameters including the height, length, position, inclination angle and open area ratio of the slots, a series of new parameters are put forward to increase the freedom of the slot meridional profile. An in-house design optimization platform is constructed based on NSGA-II and Kriging surrogate model to perform the optimization. A Pareto Front is obtained through optimization, from which the optimal design is selected by comprehensively considering both stability and efficiency performances of the compressor, i.e. the stall margin is improved by 11.23% in conjunction with the peak efficiency reduced by 0.21%. The database is analyzed to investigate how different parameters affect the performance of the slots. Three non-dominated representative designs are selected from the Pareto Front and their influencing mechanisms on stability and efficiency are further studied. Results show that the application of slots would generate a circulated flow, which exerts suction and reinjection effects at the rotor tip region and alleviate the blockage in the blade passages. Entropy analysis indicates that the viscous shearing interaction between the reinjection flow and incoming main flow causes additional entropy generation, thus slightly reducing the peak efficiency of the compressor.

In this study, inspired by the limit streamlines on the compressor casing. Combined with computer data technology to reduce the efficiency loss caused by the increase of casing processing.

The aim of this study was to investigate the effect of integripetal rhodiola herb on pulmonary arterial remodeling and expression of vascular endothelial growth factor (VEGF) in high altitude pulmonary hypertension in rats. Fifty healthy male Wistar rats were divided into five groups randomly: Plain control group (LC group), 10-day plateau group (H(10) group), 30-day plateau group (H(30) group), 10-day rhodiola-treated plateau group (R(10) group), and 30-day rhodiola-treated plateau group (R(30) group). Each group included 10 rats. The rats in LC group were kept in Chengdu (500 meters above sea level), and rats in H and R groups were kept in Lhasa (3 700 meters above sea level). The rats in R group were daily treated with integripetal rhodiola herb extract (24%, 10 mL/kg) intragastrically for 10 d or 30 d, while rats in LC and H groups were treated with the same volume of saline. Mean pulmonary arterial pressure (mPAP) was detected via a catheter in the pulmonary artery by pressure waveform monitoring. The ratio value of right ventricle weight to left ventricle plus septum weight [RV/(LV + S)] was measured. The microstructure of pulmonary arterioles was examined by electron microscopy. The expression of VEGF in the lung was investigated using immunohistochemistry. The results showed that mPAP and [RV/(LV + S)] in H(10) group and H(30) group were higher than those in LC group (P0.05); but there was no significant difference between H(10) group and R(10) group (P0.05); and mPAP and [RV/(LV + S)] in H(30) group were lower than those in H(30) group (P0.05). Electron microscopy showed that compared to LC group, arteriolar endothelial cells were arranged in a columnar or palisading form, protruding into the lumen, accompanied with luminal stenosis, irregular internal elastic membrane, and proliferation of vascular smooth muscle cells in H groups, which was more obvious in H(30) group than in H(10) group; while these pathological changes were attenuated in the R groups compared to H groups. The levels of VEGF protein in H groups were also higher than those in LC group (P0.05); while the expression of VEGF in R(30) group was lower than that in H(30) group. In summary, the results show that the integripetal rhodiola herb can attenuate high altitude-induced pulmonary arterial remodeling in rats, and the inhibition of VEGF protein expression by rhodiola may be one of the mechanisms.