This paper presents results of aerodynamic enhancement of axial compressors utilizing optimum natural aspiration through a circumferential slot made within the casing wall upstream the rotor blades ...row. The method of investigation is based on numerical simulation of flow field. Geometries of the slot walls were optimized to find the maximum stall margin and pressure ratio of the compressor. The optimum case is accompanied by boosting more momentum within the blades tip region through the slot. Consequently, tip leakage vortex flow weakens and compressor stability margin increases. Final results showed that in comparison to the untreated casing, the optimum geometry of the slot causes the total pressure ratio and stall margin to increase by 4.2% and 3%, respectively. This state-of-the-art technique is simple and economic which can be easily implemented in practical cases while the compressor is exposed to commencement of flow instabilities in the forms of the rotating stall or surge phenomena.
Blades tip leakage flow structure in axial compressors has dominant effects on flow stability and losses. Accordingly, in the present study, three different ideas are introduced for alleviation of ...undesirable effects of the blades tip leakage flow. These ideas utilize circumferential tape, S-shape nozzle and natural aspiration slot, all imposed upstream the rotor blades row. The method of investigation is based on numerical simulation of the governing flow field. Results, in terms of the flow field structure and performance curves are compared with those of the untreated case. Final results, showed that the natural aspiration idea works better than the other ones. In comparison to the plane case, it is accompanied by augmentation of 3.5% in the total pressure ratio and 3% in the surge margin. It was also found that the mass flow rate passing through the blades row tip gap has increased by 2.33 g/s in the natural aspiration case.
Abstract
In this report, the novel UiO‑66‑NH
2
based-MOF(Zr) catalytic system which further modified with nitrogen-rich organic ligand (5-aminotetrazole) using post synthetic modification (PSM) ...approach has been prepared here as an efficient catalyst to promote the A
3
-coupling preparation of propargyl amines in green aquatic media. This newly highly efficient catalyst was synthesized upon Zr-based MOF (UiO‑66‑NH
2
) which successfully functionalized with 2,4,6‑trichloro‑1,3,5‑triazine (TCT) and 5‑aminotetrazole, following through stabilization of gold metal (Au) nanopartilces. The addition of
N
-rich organic ligand through post-synthesis modification which can be assisted to stabilize the bister and stable gold nanoparticles caused to unique structure of the final composite in favor of the progress of the A
3
coupling reaction. Also several strategies comprising XRD, FT-IR, SEM, BET, TEM, TGA, ICP, EDS and elemental mapping analyzes, were used to indicate the successful preparation of the UiO-66-NH
2
@ Cyanuric Chloride@ 5-amino tetrazole/Au-NPs. The results of productivity catalyst are accomplished in good to excellent yields for all sort of reactions under mild conditions which is a proof of superior activity heterogeneous catalyst containing Au-nanoparticles. In addition, the suggested catalyst represented excellent reusability with no remarkable loss in activity up 9 sequential runs.
Different modes of transitional flows are numerically analyzed in a two-stage low-pressure axial turbine, while being exposed to various clocking of second stator blades and results are presented in ...this paper. The numerical method utilizes coupled approach of SST k-ω turbulence andγ−Re˜θt transitional models. Kinematic of the wake flow in the blades passage and flow topology are presented and discussed. Different types of transitional flows including “separation induced transition” (i.e., “laminar separation bubble”), “reverse transition” and “bypass transition” are distinguished. Results of surface distribution of pressure and skin friction coefficients, turbulence intensity, intermittency and also transition momentum thickness Reynolds number are presented for the worst and optimum clocking cases, in detail. Results show that the onset points of separation induced transition and bypass transition move upstream by 6.64% and 5.47% in the optimum clocking in comparison to the worst case, respectively. In the optimum clocking the separation bubble length decreases by 1.57% and the onset point of the reverse transition moves downstream by 1.2%. All these beneficial effects happen basically as a result of impinging the first stage wake flow on the leading edge of the second stator blade suction side, which in turn, causes transition from laminar to turbulent to occur within the boundary layer.
Herein, two novel mesoporous cross-linked poly(vinyl imidazole)s with sulfonic acid tags, PVI-SO3HCl (1) and PVI-SO3HFeCl4 (2), were prepared and characterized by a variety of techniques such as ...Fourier transform infrared spectroscopy, scanning electron microscopy, elemental mapping, energy dispersive X-ray analysis, transmission electron microscopy, thermal gravimetry, derivative thermal gravimetry, and N2 adsorption–desorption isotherms (Brunauer–Emmett–Teller). In addition, magnetic properties of poly(vinyl imidazole) sulfonic acid iron(IV) chloride PVI-SO3HFeCl4 (2) as an ionically tagged magnetic polymer were investigated using a vibrating sample magnetometer. The presented polymers, PVI-SO3HCl (1) and PVI-SO3HFeCl4 (2), were successfully applied as reusable and efficient catalysts for the preparation of N-heterocycle spiropyrans. The described catalysts were recycled and reused with a marginal decrease in their catalytic activities. The desired products were prepared under mild and green conditions. The structures of the obtained products were confirmed by various analysis techniques.
Despite the fact that studies indicate that earthquake trauma is associated with numerous psychological consequences, the mediating mechanisms leading to these outcomes have not been well-studied. ...Therefore, this study investigates the relationship between trauma exposure with substance use tendency, depression, and suicidal thoughts, with the mediating role of peritraumatic dissociation and experiential avoidance.
The descriptive-correlational approach was employed in this study. The participants were people who had experienced the Kermanshah earthquake in 2017. A total of 324 people were selected by convenient sampling method. The Traumatic Exposure Severity Scale, the Peritraumatic Dissociative Experiences Questionnaire, the Acceptance and Action Questionnaire, the Iranian Addiction Potential Scale, Beck's Depression Inventory BDI-II, and Beck's Suicidal Thoughts Scale were used to collect data. The gathered data was analyzed using structural equation modeling in SPSS Ver. 24 and LISREL Ver. 24.
The study findings indicated that the intensity of the trauma exposure is directly and significantly associated with depression symptoms, peritraumatic dissociation, and experiential avoidance. The severity of exposure to trauma had a significant indirect effect on the tendency to use substances through experiential avoidance. This is while the severity of the trauma experience did not directly correlate with substance use and suicidal thoughts. In addition, peritraumatic dissociation did not act as a mediator in the relationship between the severity of trauma exposure with substance use, depression, and suicidal thoughts.
The severity of exposure to the earthquake was associated with symptoms of depression and these findings indicate the importance of experiential avoidance in predicting the tendency to use drugs. Hence, it is essential to design and implement psychological interventions that target experiential avoidance to prevent drug use tendencies and to establish policies that lower depression symptoms following natural disasters.
Background
Aneurysmal subarachnoid hemorrhage results in significant mortality and disability, which is worsened by the development of delayed cerebral ischemia. Tests to identify patients with ...delayed cerebral ischemia prospectively are of high interest.
Objective
We created a machine learning system based on clinical variables to predict delayed cerebral ischemia in aneurysmal subarachnoid hemorrhage patients. We also determined which variables have the most impact on delayed cerebral ischemia prediction using SHapley Additive exPlanations method.
Methods
500 aneurysmal subarachnoid hemorrhage patients were identified and 369 met inclusion criteria: 70 patients developed delayed cerebral ischemia (delayed cerebral ischemia+) and 299 did not (delayed cerebral ischemia−). The algorithm was trained based upon age, sex, hypertension (HTN), diabetes, hyperlipidemia, congestive heart failure, coronary artery disease, smoking history, family history of aneurysm, Fisher Grade, Hunt and Hess score, and external ventricular drain placement. Random Forest was selected for this project, and prediction outcome of the algorithm was delayed cerebral ischemia+. SHapley Additive exPlanations was used to visualize each feature's contribution to the model prediction.
Results
The Random Forest machine learning algorithm predicted delayed cerebral ischemia: accuracy 80.65% (95% CI: 72.62–88.68), area under the curve 0.780 (95% CI: 0.696–0.864), sensitivity 12.5% (95% CI: −3.7 to 28.7), specificity 94.81% (95% CI: 89.85–99.77), PPV 33.3% (95% CI: −4.39 to 71.05), and NPV 84.1% (95% CI: 76.38–91.82). SHapley Additive exPlanations value demonstrated Age, external ventricular drain placement, Fisher Grade, and Hunt and Hess score, and HTN had the highest predictive values for delayed cerebral ischemia. Lower age, absence of hypertension, higher Hunt and Hess score, higher Fisher Grade, and external ventricular drain placement increased risk of delayed cerebral ischemia.
Conclusion
Machine learning models based upon clinical variables predict delayed cerebral ischemia with high specificity and good accuracy.
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•This is the first experimental study to evaluate the effect of T. lestoquardi infection on the cardiovascular system of infected sheep by biochemical, pathological and ...electrocardiographic methods.•T. lestoquardi infection was caused to increase in cTnI, LDH and AST activities and to decrease CPK activity.•Electrocardiography revealed sinus tachycardia, sinus arrhythmia, sino-atrial (SA) block and ST-elevation, atrial premature beat, alteration in QRS and T waves amplitude.•Heart histopathological examination showed infiltration of mononuclear inflammatory cells, endocarditis and focal necrosis of cardiac muscle cells.
The malignant ovine theileriosis is caused by Theileria lestoquardi, which is highly pathogenic in sheep. Theileriosis involves different organs in ruminants, but the effect of the disease on the cardiovascular system is unclear. To understand the pathogenesis of T. lestoquardi on the cardiovascular system, Baluchi breed sheep were infected with the mentioned parasite by releasing unfed adults of Hyalomma anatolicum anatolicum, which were infected with T. lestoquardi. The infected sheep were clinically examined on days 0, 2, 5, 7, 10, 12, 14, 17, and 21, and the blood samples were collected for biochemical parameters measurement. At termination of the experiment, the infected sheep were euthanized and pathological examinations of heart tissue were conducted. During experimental infection of sheep with T. lestoquardi, activities of cardiac troponin I (cTnI), lactate dehydrogenase, and aspartate aminotransferase, were significantly increased (P˂0.05), while a conspicuous decrease (P˂0.05) was observed in creatine phosphokinase activities. Alterations made in biochemical factors almost coincided with the presence of piroplasm in the blood and schizont in lymph nodes. Maximum and minimum of parasitemia in the sheep stood between 3.3% and 0.28%, respectively. In addition, electrocardiography revealed sinus tachycardia, sinus arrhythmia, sino-atrial block and ST-elevation, atrial premature beat, and alteration in QRS and in T waves’ amplitude. Heart histopathological examination showed hyperemia, infiltration of mononuclear inflammatory cells into interstitial tissue, endocarditis, and focal necrosis of cardiac muscle cells. In addition, in one of the sheep, definite occurrence of infarction was observed. The results indicate that T. lestoquardi infection has devastating pathological impacts on the cardiovascular system of sheep. Furthermore, measurement of the cTnI amount is a useful biochemical factor for diagnosis and for better understanding of the severity and progression of the disease and its effects on cardiac tissue.
Abstract
Background
Neuroendocrine tumors (NETs), as a rare and heterogeneous category of solid tumors, feature various morphologies and behaviors. In recent years, the incidence of NETs has ...continued to increase. Endoscopic mucosal resection (EMR) is one of the therapeutic modalities for the treatment of gastric and rectal NETs.
Methods
We evaluated patients with well-differentiated NETs of the stomach, duodenum, or rectum between 2011 and 2018. In this study, all cases with tumors confined to the mucosal or submucosal layers and smaller than 20 mm were resected using the EMR technique. We used EUS, CT scan, or MRI to exclude patients with advanced disease. All patients were actively monitored for recurrence according to the recommended protocols.
Results
A total of 36 patients with NETs entered the study; 17 (47.2%) were female and the remaining 19 (52.8%) were male, with a total age range of 20–74 years (mean: 52.47 ± 13.47 years). Among the tumors, 31 cases (86.1%) were G1 and the remaining 5 (13.9%) were G2. Based on the pathology reports, 22 tumors (61.1%) were smaller than 1 cm, while the remaining 14 (38.9%) were between 1–2 cm. Twenty-two patients (61.1%) had a margin of specimen involved with the tumor. No recurrence was observed during the mean follow-up time of 63.5 ± 19.8 months (range: 39–103 months). All 36 cases survived during the study period.
Conclusion
Conventional EMR procedure provides low chance of R0 (complete resection) achievement in gastrointestinal NETs smaller than 20 mm and limited to the mucosa or sub mucosa. However, it could be an option if patients are closely followed. Postoperative marginal involvement is not a reliable predictor of disease recurrence, which may be explained by the deleterious effect of heat coagulation and cauterization applied during tumor removal.
A large body of evidence indicated that patients with schizophrenia spectrum disorders show deficit in perceptual and visual processing, but little is known about the origin of this defect. One of ...the strategies used to reveal the origin of such defects is to use tests that have a strong neuropsychological basis in normal individuals. In this study, we used the Hermann grid task to reveal the source of visual deficit in patients with schizophrenia. Several findings have shown that the Hermann grid illusion results from lateral inhibition of neuro-visual pathway cells. We compared 26 patients with schizophrenia to 26 participants with high schizotypy traits and 26 normal controls in a computer test we designed for the Hermann grid illusion. Chi-square analysis revealed that the patients with schizophrenia and the participants with high schizotypy traits reported significantly less the Hermann grid illusion than healthy controls. Therefore, the results support the hypothesis of a defect in lateral inhibition of patients with schizophrenia. This might suggest that the visual pathway cells in schizophrenic patients failed to properly combine the data from the visual receptors as they do in healthy people.
•The Hermann grid illusion has wealthy neuropsychological background.•Visual perception difficulties in schizophrenia have been always reported.•Patients with schizophrenia do not report the Hermann grid illusion.•Evidence show that lateral inhibition contributes in the Hermann grid illusion.•Lack of Hermann grid illusion support a lateral inhibition defect in schizophrenia.
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