Vibration investigation of rotor system with unbalance and blade-casing rubbing coupling faults

In order to investigate the mechanism of a rotor system with unbalance and blade-casing rubbing coupling faults, the vibration and rub force in a rotor system resulting from unbalance and blade-casing rubbing coupling faults are simulated. At first, a dynamic model of 0-2-1 form rotor is established, and a blade-casing model, which considered blade number, clearance between the blade tip and stator, stiffness and size of the blade, is introduced to the rotor model. The characteristics of unbalance and blade-casing rubbing coupling faults are analyzed by waterfall plot, spectrum, time domain chart of vibration and rub force, and the effects of speed and clearance between the blade tip and stator. Secondly, a rotor system tester is established according to the model structure. The experimental test of rubbing is simulated by adjusting the Feeding Device to control the clearance between the blade and stator. After simulation and experimental results were compared, it was found that fraction frequencies and high integer frequencies were affected by a blade-casing rubbing fault, the clearance and speed had different influence on the dynamic characteristic of rotor system with blade-casing rubbing fault

Vibration investigation of rotor system with unbalance and blade-casing rubbing coupling faults

In order to investigate the mechanism of a rotor system with unbalance and blade-casing rubbing coupling faults, the vibration and rub force in a rotor system resulting from unbalance and blade-casing rubbing coupling faults are simulated. At first, a dynamic model of 0-2-1 form rotor is established, and a blade-casing model, which considered blade number, clearance between the blade tip and stator, stiffness and size of the blade, is introduced to the rotor model. The characteristics of unbalance and blade-casing rubbing coupling faults are analyzed by waterfall plot, spectrum, time domain chart of vibration and rub force, and the effects of speed and clearance between the blade tip and stator. Secondly, a rotor system tester is established according to the model structure. The experimental test of rubbing is simulated by adjusting the Feeding Device to control the clearance between the blade and stator. After simulation and experimental results were compared, it was found that fraction frequencies and high integer frequencies were affected by a blade-casing rubbing fault, the clearance and speed had different influence on the dynamic characteristic of rotor system with blade-casing rubbing fault

Tailoring mSiO2-SmCox nanoplatforms for magnetic/photothermal effect-induced hyperthermia therapy

Hyperthermia therapy is a hotspot because of its minimally invasive treatment process and strong targeting effect. Herein, a synergistic magnetic and photothermal therapeutic nanoplatform is rationally constructed. The well-dispersive mSiO2-SmCox nanoparticles (NPs) were synthesized through a one-step procedure with the regulated theoretical molar ratio of Sm/Co among 1:1, 1:2, and 1:4 for controlling the dispersion and magnetism properties of SmCox NPs in situ growth in the pore structure of mesoporous SiO2 (mSiO2), where mSiO2 with diverse porous structures and high specific surface areas serving for locating the permanent magnetic SmCox NPs. The mSiO2-SmCox (Sm/Co = 1:2) NPs with highly dispersed and uniform morphology has an average diameter of ∼73.08 nm. The photothermal conversion efficiency of mSiO2-SmCox (Sm/Co = 1:2) NPs was determined to be nearly 41%. The further in vitro and in vivo anti-tumor evaluation of mSiO2-SmCox (Sm/Co = 1:2) NPs present promising potentials for hyperthermia-induced tumor therapy due to magnetic and photothermal effects

Low levels of vitamin C in dialysis patients is associated with decreased prealbumin and increased C-reactive protein

<p>Abstract</p> <p>Background</p> <p>Subclinical inflammation is a common phenomenon in patients on either continuous ambulatory peritoneal dialysis (CAPD) or maintenance hemodialysis (MHD). We hypothesized that vitamin C had anti-inflammation effect because of its electron offering ability. The current study was designed to test the relationship of plasma vitamin C level and some inflammatory markers.</p> <p>Methods</p> <p>In this cross-sectional study, 284 dialysis patients were recruited, including 117 MHD and 167 CAPD patients. The demographics were recorded. Plasma vitamin C was measured by high-performance liquid chromatography. And we also measured body mass index (BMI, calculated as weight/height²), Kt/V, serum albumin, serum prealbumin, high-sensitivity C-reactive protein (hsCRP), ferritin, hemoglobin. The relationships between vitamin C and albumin, pre-albumin and hsCRP levels were tested by Spearman correlation analysis and multiple regression analysis.</p> <p>Patients were classified into three subgroups by vitamin C level according to previous recommendation <abbrgrp><abbr bid="B1">1</abbr><abbr bid="B2">2</abbr></abbrgrp> in MHD and CAPD patients respectively: group A: < 2 ug/ml (< 11.4 umol/l, deficiency), group B: 2-4 ug/ml (11.4-22.8 umol/l, insufficiency) and group C: > 4 ug/ml (> 22.8 umol/l, normal and above).</p> <p>Results</p> <p>Patients showed a widely distribution of plasma vitamin C levels in the total 284 dialysis patients. Vitamin C deficiency (< 2 ug/ml) was present in 95(33.45%) and insufficiency (2-4 ug/ml) in 88(30.99%). 73(25.70%) patients had plasma vitamin C levels within normal range (4-14 ug/ml) and 28(9.86%) at higher than normal levels (> 14 ug/ml). The similar proportion of different vitamin C levels was found in both MHD and CAPD groups.</p> <p>Plasma vitamin C level was inversely associated with hsCRP concentration (Spearman r = -0.201, P = 0.001) and positively associated with prealbumin (Spearman r = 0.268, P < 0.001), albumin levels (Spearman r = 0.161, P = 0.007). In multiple linear regression analysis, plasma vitamin C level was inversely associated with log₁₀hsCRP (P = 0.048) and positively with prealbumin levels (P = 0.002) adjusted for gender, age, diabetes, modality of dialysis and some other confounding effects.</p> <p>Conclusions</p> <p>The investigation indicates that vitamin C deficiency is common in both MHD patients and CAPD patients. Plasma vitamin C level is positively associated with serum prealbumin level and negatively associated with hsCRP level in both groups. Vitamin C deficiency may play an important role in the increased inflammatory status in dialysis patients. Further studies are needed to determine whether inflammatory status in dialysis patients can be improved by using vitamin C supplements.</p

Circulating Endothelial Cells and Chronic Kidney Disease

Endothelial dysfunction may play a crucial role in initiation of the pathogenesis of vascular disease and atherosclerosis. The identification and quantification of circulating endothelial cells (CEC) have been developed as a novel marker of endothelial function. We describe, in great detail, mechanisms of endothelial dysfunction and CEC detachment. We also review the relationship between numbers of CEC and disease severity and response to treatment. In addition, we describe the possible clinical use of CEC in chronic kidney disease (CKD) and kidney transplantation. In summary, CEC have been developed as a novel approach to assess the endothelial damage. Measurement of the CEC level would provide an important diagnostic and prognostic value on the endothelium status and the long-term outcome of vascular dysfunction

Effect of Thermal Growth Oxide Composition and Morphology on Local Stresses in Thermal Barrier Coatings

The failure of thermal barrier coatings (TBCs) during operation depends mainly on the thermal mismatch between the ceramic top coat (TC) and the metal bond coat (BC). The thermal mismatch at the interface is influenced by the dynamic changes in the composition and morphology of the thermally grown oxide (TGO) between TC and BC during thermal cycling. This work focuses on the establishment of a TGO dynamic growth model, which considers the changes in TGO composition and morphology for investigating the effect of dynamic growth of TGO on local mismatch stresses during thermal cycling. The results show that the sharp locations at the TGO/BC interface are more prone to high tensile stresses during thermal cycling due to the uneven growth behavior of TGO, leading to crack initiation. The valley region of the interface is in a state of compressive stress &sigma;xx during the early stages of thermal exposure. The peak region preferentially forms a concentration of tensile stress &sigma;yy. Once large-scale &ldquo;layer&rdquo; (Ni, Co)Al2O4-based spinel-like mixed oxides(MO) growth occurs in TGO, the stress &sigma;xx changes from compressive stress to tensile stress in the valley region, eventually forming high tensile stress (Max: +158 MPa). The maximum tensile stress &sigma;yy in the peak region is increased to 256 MPa, which is more than two times larger than the early period of thermal exposure. As a result, the dramatic changes in local stresses seriously affect the time and location of microcracks

Comprehensive use of a high-frequency electric knife, balloon dilatation, and cryotherapy for tuberculous central tracheobronchial cicatricial constriction

Abstract Background To examine the benefits of interventional therapy for cicatricial constriction using a high-frequency electric knife, saccular dilatation, and cryotherapy. Methods This case series included patients with central tracheobronchial cicatricial constriction admitted to the Department of Tuberculosis of Henan Provincial Chest Hospital from July 2018 to March 2021 and treated with bronchoscopic interventional therapies based on systemic anti-tuberculosis treatment. Results 96 patients were included, in whom 443 interventional therapies were performed. The total mid-(3 months) and long-term (12 months) effective rates were both 100%. The internal diameter of tracheobronchial stenosis increased after the operation, and the difference was statistically significant (all < 0.05). After interventional treatment, patients’ symptoms of choking sensation in the chest and shortness of breath were relieved. Respiratory function was obviously improved. The ratios of hemorrhage, granulation hyperplasia, chest pain, and postoperative fever were 58.2%, 42.6%, 31.3%, and 26.7%, respectively. No focal transmission and progression of tuberculosis occurred, and no serious complications were observed. Conclusion The use of a high-frequency electric knife, saccular dilatation, and/or cryotherapy according to the pathological stage of the tracheobronchial cicatricial constriction is feasible, with good mid- and long-term curative effects and few complications

Association between the triglyceride-glucose index and calcified aortic stenosis in elderly patients: a cross-sectional study

Abstract Insulin resistance (IR) is associated with a variety of cardiovascular diseases, but there are few studies on the correlation between IR and calcified aortic stenosis (CAS). In this study, the triglyceride-glucose (TyG) index, which reflects IR, was used to investigate the correlation between IR and CAS. The study included 183 elderly patients who were diagnosed with CAS by transthoracic echocardiography. The patients were matched 1:1 according to age and sex, and elderly patients who were hospitalized during the same period and underwent transthoracic echocardiography without aortic stenosis were included as the control group. The relationship between the TyG index and CAS was analyzed by a multivariable logistic regression model, curve fitting and trend test. Multivariate logistic regression analysis showed that the TyG index as a continuous variable was negatively associated with CAS (P < 0.001); trend tests and curve fitting further supported this association. Our study showed that the TyG index was negatively associated with CAS in elderly patients, which may be related to the impairment of insulin receptors and signaling pathways in IR