Search

Cylindrical milling of a screw rotor groove in a single screw compressor has higher machining efficiency than turning. However, the screw groove bottom produced by the flat end of the milling cutter fails to mesh hermetically with the flat tooth tip due to the oversized clearance between them. The clearance forms two leakage paths leading to a compressed gas leakage. The shape of the path is roughly the same as that of two parallel oblate divergent nozzles in an inverse orientation. A mathematical simulation is presented for the surface profile of the screw groove bottom for a single screw compressor generated using several cylindrical milling cutters. The results contribute to improving the design of the meshing pairs in the single screw compressor. [DOI: 10.1115/1.3151802] Keywords: screw groove bottom, single screw compressor, surface profile, grooves and tooth tips, cylindrical milling, geometrical simulation

Background and objective: Nationally representative reports on the characteristics and long‐term survival of pulmonary arterial hypertension (PAH) from developing countries are scarce. The applicability of the current main risk stratifications and the longitudinal changes in goal‐oriented treatments have yet to be elucidated in real‐world settings. Therefore, we aimed to provide insights into the characteristics, goal‐oriented treatments and survival of PAH in China and to explore the applicability of the main risk stratifications in our independent cohort. Methods: PAH patients were consecutively enrolled from a national prospective multicentre registry. Data on baseline, follow‐up re‐evaluation and therapeutic changes were collected. Results: A total of 2031 patients were enrolled, with congenital heart disease (CHD)‐PAH (45.2%) being the most common aetiology. The mean age was 35 ± 12 years, and 76.2% were females. At baseline, approximately 20% of the patients with intermediate or high risk received combination treatment. At follow‐up, approximately half of the re‐evaluated patients did not achieve low‐risk profiles, and even among patients who received combination therapy at baseline, 4% of them still worsened. The rate of combination therapy increased significantly from 6.7% before 2015 to 35.5% thereafter. The main risk assessment tools demonstrated good performance for predicting survival both at baseline and at follow‐up. Conclusion: Chinese PAH patients show both similar and distinct features compared to other countries. Current main risk stratifications can significantly discriminate patients at different risk levels. There were still many patients not achieving low‐risk profiles at follow‐up, indicating more aggressive treatment should be implemented to optimize the goal‐oriented treatment strategy. This Chinese registry study revealed that Chinese patients with pulmonary arterial hypertension showed both similar and distinct features compared to other countries. Many patients did not achieve low‐risk profiles at follow‐up, indicating more aggressive treatment should be implemented to optimize goal‐oriented therapy for these patients. [ABSTRACT FROM AUTHOR]

Single screw compressor (SSC), a strong competitor of the twin screw compressor, is regarded as an excellent gas compressor because of symmetrical structure and balanced gas forces on the screw rotor. However, the market for the SSC is tiny compared with that for the twin screw compressor because of the serious abrasion of star-wheel teeth. In recent years, this problem has been solved due to the development of the new profiles of meshing pairs, and the SSC has attracted more attention due to its high application potential for low-temperature heat pump, mechanical vapor recompression, and two-phase expansion. Nevertheless, there are still many technical problems remained to be solved for applying SSC to these fields urgently. In this paper, a comprehensive review on the progress and development of SSC technologies is presented. The review first combs the current situation of SSC products. Besides, the design and processing of meshing pairs are clarified and analyzed. Moreover, the working process of SSC and its performance in new applications are discussed in detail. Finally, the further research direction of the SSC is also discussed, which will be beneficial for designing high-efficiency SSC. [ABSTRACT FROM AUTHOR]

• A novelty screw rotor structure is proposed to smooth the compressed gas-force torque. • A novelty method is presented to calculate the gas force and torque of screw rotor. • The compressed gas-force torque of the screw rotor is contrastively analyzed. • The influences of the pressure difference and compression capacity are discussed. • The load brought by the novelty structure on the bearing is investigated. Recently, the single screw compressor (SSC) has been applied in the low-temperature heat pump system with the purpose of achieving higher system efficiency. However, the traditional SSC with even-grooves screw rotor behaves high torque fluctuation to the motor, thanks to its work synchronously and doubled compressed gas-induced torque on the screw rotor axis. It is more serious in the low-temperature heat pump system because of the higher pressure ratio. In this paper, an odd-grooves screw rotor design is proposed to smooth the compressed gas-induced torque on the screw rotor axis, by arranging the two compression chambers work alternatively. A dynamic model for the screw rotor is established to calculate the gas force and the gas-induced torque on screw rotors under different working conditions. The results show that the odd-grooves screw rotor design can remarkably reduce the gas-induced torque fluctuation of the SSC. Meanwhile, the maximal load on the bearing caused by the odd grooves design could be controlled below the maximum allowable load of the bearing. [ABSTRACT FROM AUTHOR]

Background: Buyang Huanwu Decoction (BHD) is a classical Chinese Medicine formula empirically used for diabetic nephropathy (DN). However, its therapeutic efficacies and the underlying mechanisms remain obscure. In our study, we aim to evaluate the renoprotective effect of BHD on a streptozotocin (STZ)-induced diabetic nephropathy mouse model and explore the potential underlying mechanism in mouse mesangial cells (MCs) treated with high glucose in vitro, followed by screening the active compounds in BHD. Methods: Mice were received 50 mg/kg streptozotocin (STZ) or citrate buffer intraperitoneally for 5 consecutive days. BHD was intragastrically administrated for 12 weeks starting from week 4 after the diabetes induction. The quality control and quantitative analysis of BHD were studied by high-performance liquid chromatography (HPLC). Renal function was evaluated by urinary albumin excretion (UAE) using ELISA. The mesangial matrix expansion and renal fibrosis were measured using periodic acid-schiff (PAS) staining and Masson Trichrome staining. Mouse mesangial cells (MCs) were employed to study molecular mechanisms. Results: We found that the impaired renal function in diabetic nephropathy was significantly restored by BHD, as indicated by the decreased UAE without affecting the blood glucose level. Consistently, BHD markedly alleviated STZ-induced diabetic glomerulosclerosis and tubulointerstitial injury as shown by PAS staining, accompanied by a reduction of renal inflammation and fibrosis. Mechanistically, BHD inhibited the activation of TGF-β1/Smad3 and NF-κB signaling in diabetic nephropathy while suppressing Arkadia expression and restoring renal Smad7. We further found that calycosin-7-glucoside (CG) was one of the active compounds from BHD, which significantly suppressed high glucose-induced inflammation and fibrosis by inhibiting TGF-β1/Smad3 and NF-κB signaling pathways in mesangial cells. Conclusion: BHD could attenuate renal fibrosis and inflammation in STZ-induced diabetic kidneys via inhibiting TGF-β1/Smad3 and NF-κB signaling while suppressing the Arkadia and restoring renal Smad7. CG could be one of the active compounds in BHD to suppress renal inflammation and fibrosis in diabetic nephropathy. [ABSTRACT FROM AUTHOR]

Viral myocarditis (VMC) is the major cause of sudden death in adolescents. To date, no effective treatment has been identified for VMC. Studies have shown that T helper (Th) cells such as Th1, Th2, Th17, and Th22 cells are involved in the pathogenesis of VMC. However, the role of B cells and their impact on Th cells in VMC is unclear. In this study, we investigated the role of B cells in Th cell differentiation in myocardial damage in an animal model of VMC. C57BL/6 mice were infected with Coxsackievirus B3 (CVB3) intraperitoneally or injected with phosphate-buffered saline as a control condition. At day 7, samples from these mice were analyzed by histology, ELISA, flow cytometry, and gene expression assays. We found that TNF-α-, IL-6-, and IL-17-producing B cell numbers were significantly increased, while IL-4-producing B cell population was significantly reduced in acute VMC. Furthermore, we performed B cell knockout (BKO), SCID, and SCID+B cells reconstitution experiments. We found that BKO alleviated the cardiac damage following CVB3 infection, may hamper the differentiation of Th1 and Th17 cells, may promote the differentiation of Th2 cells, and proved ineffective for the differentiation of Th22 cells. In contrast, SCID+B cells reconstitution experiment exacerbated the cardiac damage. Ex vivo studies further revealed that B cells promote the differentiation of Th1 and Th17 cells and inhibit the differentiation of Th2 cells. Our study shows that B cells are activated and have strong abilities of antigen presentation and producing cytokines in VMC; B cells not only play a pathogenic role in VMC independent of T cells but also promote Th1 and Th17 cell differentiation, and hamper Th2 cell differentiation in VMC. [ABSTRACT FROM AUTHOR]

This paper introduces a new meshing pair profile envelope by multicolumn in single screw compressors. The screw groove flank of the new meshing pair is a multisegment surface, and the star-wheel tooth flank consisted of multicylindrical surfaces. When the compressor is operating, the position of the contact line on the tooth flank with the screw groove flank uniformly moves in one revolution, which is rather different from the stationary contact position of existing meshing pair profiles. The new meshing pair will result in the improved wear-resistance and longer operation life, lower gas leakage, and higher efficiency of the compressor. [DOI: 10.1115/1.3151799]