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56 result(s) for "Zhang, Hexuan"
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Numerical Investigations and Optimized Design of the Active Cooling Performance with Phase Change for Aircraft Rudder Shaft
During hypersonic flight, the air rudder shaft can undergo huge aerodynamic heating load, where it is necessary to design the thermal protection system of the air rudder shaft. Aiming to prevent the rudder shaft from thermal failure due to the heat endurance limit of materials, numerical investigations are conducted systemically to predict the active cooling performance of the rudder shaft with liquid water considering phase change. The validation of the numerical simulation method considering phase-change heat transfer is further investigated by experiments. The effect of coolant injection flow velocity on the active cooling performance is further analyzed for both the steady state and transient state. Finally, to achieve better cooling performance, an optimized design of the cooling channels is performed in this work. The results of the transient numerical simulation show that, employing the initial cooling structures, it may undergo the heat transfer deterioration phenomenon under the coolant injection velocity below 0.2 m/s. For the rudder shaft with an optimized structure, the heat transfer deterioration can be significantly reduced, which significantly reduces the risk of thermal failure. Moreover, the total pressure drop of the optimized rudder shaft under the same coolant injection condition can be reduced by about 19% compared with the initial structure. This study provides a valuable contribution to the thermal protection performance for the rudder shaft, as a key component of aircraft under the aero heating process.
Meriones unguiculatus serves as a spontaneous primary aldosteronism rodent model
Primary aldosteronism (PA) is the most common form of endocrine hypertension. The available animal models of PA rely on gene manipulation, thus fail to duplicate the general pathological process of PA in humans. Meriones unguiculatus (MU) has been reported to possess a large size of adrenal gland and an elevated ability to save water. In this study, we aimed to confirm whether MU can serve as an ideal animal model of PA. Sprague Dawley rats of the same body weight (SD1) or age (SD2) as MU were used as control groups. Blood pressure and serum aldosterone, renin and electrolyte levels were measured, and the oral salt loading test was used as confirmatory test to compare the inhibition level of the renin angiotensin aldosterone system (RAAS) among the three groups. The expression and distribution of CYP11B2 (aldosterone synthase) were evaluated in the adrenal gland of each group. MU exhibited typical clinical manifestations of PA, including hypertension, hyperaldosteronism, low renin levels and strong sodium retention and potassium excretion abilities. Compared with control groups, the inhibitory effect of a high-sodium diet on the RAAS was milder in MU, accompanied by significant cardiac dysfunction. The protein expression level and distribution area of CYP11B2 were significantly increased in the adrenal gland of MU. The current study reveals that MU could serve as an ideal spontaneous PA model. The increased expression and distribution of CYP11B2 stimulate the excessive aldosterone production in a renin-independent manner, leading to a significant increase in blood pressure in MU.
Catheter-based adrenal ablation: an alternative therapy for patients with aldosterone-producing adenoma
Unilateral adrenalectomy is the standard treatment for patients with aldosterone-producing adenoma (APA), but it lacks an option for patients with APA who refuse or are not suitable for surgery. In this study, we studied whether catheter-based adrenal ablation for APA is comparable to adrenalectomy. A total of 2185 hypertensive patients were screened, and 112 patients with APA were recruited and counselled on the treatment options. Fifty-two patients opted for catheter-based adrenal ablation, and 60 opted for adrenalectomy. Clinical and biochemical outcomes were assessed at 6 months after treatment. Factors associated with hypertension remission and the advantages and limitations of this approach were evaluated. According to the primary aldosteronism surgical outcome (PASO) criteria, complete and partial clinical success was achieved in 21 (40.4%) and 23 (44.2%) patients in the ablation group vs. 33 (55.0%) and 23 (38.3%) patients in the adrenalectomy group, respectively. Complete and partial biochemical success was achieved in 30 (57.7%) and 17 (32.7%) patients in the ablation group vs. 51 (85.0%) and 5 (8.3%) patients in the adrenalectomy group, respectively. The complete clinical success rate was not (P > 0.05), but the complete biochemical success rate was significantly different between the two groups (P < 0.01). Factors associated with adrenal ablation-mediated hypertension remission were hypertension duration and serum potassium level at baseline. Compared with surgery, adrenal ablation requires a shorter operating time and time to resume physical activity. Catheter-based adrenal ablation may be an alternative and feasible option for APA patients unwilling to receive surgical treatment.
Asprosin induces vascular endothelial-to-mesenchymal transition in diabetic lower extremity peripheral artery disease
Background Altered adipokine secretion in dysfunctional adipose tissue facilitates the development of atherosclerotic diseases including lower extremity peripheral artery disease (PAD). Asprosin is a recently identified adipokine and displays potent regulatory role in metabolism, but the relationship between asprosin and lower extremity PAD remains uninvestigated. Methods 33 type 2 diabetes mellitus (T2DM) patients (DM), 51 T2DM patients with PAD (DM + PAD) and 30 healthy normal control (NC) volunteers were recruited and the blood samples were collected for detecting the circulatory asprosin level and metabolomic screening. RNA sequencing was performed using the aorta tissues from the type 2 diabetic db/db mice and human umbilical vein endothelial cells (HUVECs) were treated with asprosin to determine its impact on the endothelial-to-mesenchymal transition (EndMT). Results The circulating levels of asprosin in DM + PAD group were significantly higher than that of NC group and the DM group. Circulating asprosin level was remarkably negatively correlated with ankle-brachial index (ABI), even after adjusting for age, sex, body mass index (BMI) and other traditional risk factors of PAD. Logistic regression analysis revealed that asprosin is an independent risk factor for PAD and receiver-operator characteristic (ROC) curve determined a good sensitivity (74.5%) and specificity (74.6%) of asprosin to distinguish PAD. Data from metabolomics displayed a typical characteristics of de novo amino acid synthesis in collagen protein production by myofibroblasts in patients with PAD and activation of TGF-β signaling pathway appeared in the aortic tissue of db/db mice. Asprosin directly induces EndMT in HUVECs in a TGF-β-dependent manner as TGF-β signaling pathway inhibitor SB431542 erased the promotional effect of asprosin on EndMT. Conclusions Elevated circulatory asprosin level is an independent risk factor of lower extremity PAD and might serve as a diagnostic marker. Mechanistically, asprosin directly induces EndMT that participates in vascular injury via activation of TGF-β signaling pathway. Trial registration This trial was registered at clinicaltrials.gov as NCT05068895
Rationality and implication of catheter-based adrenal ablation for bilateral primary aldosteronism
Mineralocorticoid receptor antagonists (MRAs) for bilateral primary aldosteronism (PA) are the mainstay option recommended by guidelines, but poor compliance occurs due to numerous side effects. We aimed to examine whether catheter-based adrenal ablation could be an alternative treatment for bilateral PA.644 PA patients were included from a total of 6054 hypertensive patients. Adrenal CT scan and adrenal venous sampling (AVS) were both performed for PA subtype classification. Clinical and biochemical outcomes were assessed at 6 months after treatment according to the Primary Aldosteronism Surgical Outcome (PASO) criteria.93 patients with PA were recruited to be treated by adrenal ablation, including 25 bilateral PA and 68 unilateral PA according to AVS results. Office SBP and DBP significantly decreased from baseline levels, serum potassium levels increased and ARR significantly decreased ( p  < 0.01) in both the bilateral and unilateral groups. In the bilateral group, complete, partial and absent clinical success was achieved in 6 (24.0%), 11 (44.0%) and 8(32.0%) patients, respectively. In the unilateral group, complete, partial and absent clinical success was achieved in 12 (17.6%), 37 (54.4%), and 19 (27.9%) patients, respectively. The numbers of patients achieving complete, partial, and absent biochemical success were 15 (60.0%), 6 (24.0%), and 4 (16.0%), respectively, in the bilateral group versus 37 (54.4%), 9 (13.2%), and 22 (32.3%), respectively, in the unilateral group. In conclusion, we provide evidence for the beneficial outcomes of unilateral adrenal ablation for patients with bilateral PA. Our findings provide insight into an alternative option for patients with bilateral excess aldosterone.
Laws and Mechanism of the Fe (III) Clogging of Porous Media in Managed Aquifer Recharge
The use of stormwater for managed aquifer recharge (MAR) has become one of the most important ways to deal with water shortages and the corresponding environmental geological problems, especially in the north of China. The Fe (III) clogging of porous media is a common and significant problem that influences the effect of the infiltration rate. This paper focuses on the migration characteristics and clogging mechanisms of iron hydroxides in sand columns. The results indicate that the permeability of porous media significantly decreased at the inlet of the fine sand column and inside the coarse sand column. We demonstrated that, when the Fe (III) concentration was higher, a smaller infiltration medium size was produced more rapidly, and there was more significant clogging. More than 80% of the injected Fe (III) remained in the sand column, and more than 50% was retained within 1 cm of the column inlet. The mass retention increased with the decrease in the size of the infiltration medium particles and with the increase in the injected Fe (III) concentration. The main material that caused Fe (III) clogging was iron hydroxide colloids, which were in the form of a granular or flocculent membrane coating the quartz sand. The mechanisms of clogging and retention were blocking filtration and deep bed filtration, adsorption, and deposition, which were strongly affected by the coagulation of Fe (III) colloidal particles.
Bilateral Adrenal Ablation for the Treatment of Ectopic ACTH Syndrome With Severe Hypokalemia: A Case Report and a Literature Review
Ectopic ACTH secretion‐related Cushing's syndrome may manifest as a rapid onset of hypercortisolism, elevated urinary free cortisol (UFC) and blood ACTH concentrations, and hypokalemia. However, for patients whose primary lesions are difficult to remove, bilateral adrenalectomy is the recommended treatment method according to guidelines. Here, we present a case of non‐small cell lung cancer with metastasis. Due to significant deconditioning, the patient was unable to undergo bilateral adrenalectomy and instead underwent catheter‐based adrenal ablation; subsequently, he achieved clinical remission and completed the first phase of chemotherapy.
Assessment of sublingual microcirculation for the screening of diabetic nephropathy
Objective To investigate the potential of employing sublingual microcirculation as an early noninvasive screening technique for diabetic nephropathy (DN). Research design and methods We recruited 89 patients with type 2 diabetes mellitus (T2DM) and 41 healthy subjects in this cross-sectional observational study. All participants underwent fluorescein fundus angiography, vibration perception testing, 10 g (Semmes–Weinstein) monofilament examination, nerve conduction velocity, and 24-h urine microalbumin determination. HbA1c, fasting plasma glucose, blood lipid, and estimated glomerular filtration rate(eGFR) were measured. Sublingual microcirculatory images were captured using side-stream dark-field (SDF) microcirculation microscopy, and total and perfused vascular density (TVD and PVD) were calculated. Results The sublingual microcirculatory parameters denoting microvascular density and perfusion were negatively correlated with both fasting plasma glucose (TVD, r =  − 0.316, P  < 0.001; PVD, r =  − 0.350, P  < 0.001; PPV, r =  − 0.279, P  = 0.001) and HbA1c (TVD, r =  − 0.367, P  < 0.001; PVD, r =  − 0.423, P  < 0.001; PPV, r =  − 0.399, P  < 0.001). Diabetes patients already had a reduction in sublingual microcirculation compared with healthy control, and more severe reductions in TVD (7.07 ± 1.64 vs. 9.67 ± 1.94 mm/mm 2 , P  < 0.001) and PVD (5.88 ± 1.82 vs. 8.64 ± 2.46 mm/mm 2 , P  < 0.001) were found in those diabetes patients developed microvascular complications. Sublingual microcirculation impairment was accompanied with higher urinary albumin creatinine ratio (UACR). Receiver operating characteristic (ROC) analysis showed that TVD (area under the curve, AUC = 0.890 [0.836 0.944], P  < 0.001) and PVD (AUC = 0.883 [0.826, 0.940], P  < 0.001) could be indicators for DN screening. We derived a combined predictor index (CPI) considering both TVD and PVD for screening DN, and both the AUC (0.892, [0.838 0.945], P  < 0.001) and cutoff point of 11.30 mm/mm 2 showed great improvement (sensitivity: 95.5%, specificity: 67.4%). Conclusions Diabetes patients experienced impaired sublingual microcirculation, which was closely correlated with UACR. Sublingual microcirculation monitoring could be used for the noninvasive early detection of DN.
Flow Velocity Effects on Fe(III) Clogging during Managed Aquifer Recharge Using Urban Storm Water
Storm water harvesting and storage has been employed for nearly a hundred years, and using storm water to recharge aquifers is one of the most important ways to relieve water scarcity in arid and semi-arid regions. However, it cannot be widely adopted because of clogging problems. The risk of chemical clogging is mostly associated with iron oxyhydroxide precipitation; anhydrous ferric oxide (HFO) clogging remains a problem in many wellfields. This paper investigates Fe(III) clogging levels at three flow velocities (Darcy velocities, 0.46, 1.62 and 4.55 m/d). The results indicate that clogging increases with flow velocity, and is mostly affected by the first 0–3 cm of the column. The highest water velocity caused full clogging in 35 h, whereas the lowest took 53 h to reach an stable 60% reduction in hydraulic conductivity. For the high flow velocity, over 90% of the HFO was deposited in the 0–1 cm section. In contrast, the lowest flow velocity deposited only 75% in this section. Fe(III) deposition was used as an approximation for Fe(OH)3. High flow velocity may promote Fe(OH)3 flocculent precipitate, thus increasing Fe(III) deposition. The main mechanism for a porous matrix interception of Fe(III) colloidal particles was surface filtration. Thus, the effects of deposition, clogging phenomena, and physicochemical mechanisms, are more significant at higher velocities.
Determination of adrenal hypersecretion in primary Aldosteronism without aldosterone-production adenomas
Background Primary aldosteronism (PA) is highly prevalent in hypertensive population. Adrenal vein sampling (AVS) is the only procedure to assess adrenal aldosterone hypersecretion in PA. PA patients without aldosterone-producing adenomas (APA) frequently have unilateral aldosterone hypersecretion (UAH). These patients could bear inappropriate adrenalectomy without AVS. This study aims to identify which clinical characteristics should be recommended to perform AVS in these PA patients. Methods This study was performed from January 2018 to July 2019 at a center for hypertension and metabolic diseases. Adrenal computed tomography (CT) scan, biochemical evaluation, and AVS were performed. Results Total 141 patients were included in this study. Aldosterone to renin ratio (ARR) after confirmatory test is highly associated with adrenal laterality. The specificity of ARR > 10 (ng/dL)/(mU/L) after confirmatory test is 100%. After confirmatory test, patients with ARR > 10 (ng/dL)/(mU/L) had higher plasma aldosterone concentration and incidences of ischemic heart diseases and renal damage( p  < 0.05). Conclusions After confirmatory tests, ARR > 10 (ng/dL)/(mU/L) indicates adrenal laterality, with increasingly cardiorenal damage in PA patients without APA. Thus, AVS should be recommended in these patients before surgery. Trial registration NCT03398785 , Date of Registration: December 24, 2017.