Enlargement Of Diameter Research Articles

Drilling pressure relief under confining pressure: energy effect and numerical simulation analysis

ABSTRACT Mine pressure bump can be effectively mitigated through drilling pressure relief, with the success of this method largely dependent on the selection of appropriate drilling parameters. This study investigates the pressure relief behaviour of rock masses subjected to various drilling parameters, accounting for lateral constraints and vertical stress, and employing independently designed drilling testing equipment. A combination of theoretical research, laboratory experiments and numerical simulations was employed to derive the findings. The results indicate that increases in borehole size and depth lead to a decrease in both the peak strength of the rock mass and the accumulated elastic strain energy prior to reaching peak stress. Furthermore, higher peak stresses are transmitted to deeper sections of the rock, thereby enhancing the overall pressure relief effect. Additionally, rock creep becomes more pronounced with greater pressure relief. The study also reveals that the degree of initial rock mass damage and the frequency of acoustic emission events increase with the efficiency of pressure relief. The findings suggest that an effective strategy to optimise borehole pressure relief involves first prioritising joint pressure relief through multiple boreholes, followed by the strategic expansion of borehole diameters, and ultimately, the increase in borehole depth.

Chromatic aberration in homogeneous diameter expansion growth of AlN crystals by the PVT method

AbstractHomogeneous diameter expansion growth is the preferred method for preparing large-sized AlN single crystals using the PVT method. However, chromatic aberration between the expansion and seed regions, as well as localized chromatic aberrations within the expansion region, are commonly observed, but not deeply investigated yet. This paper investigates the homoepitaxial lateral growth of AlN crystals using Al-polar face seeds and analyzes the crystal structure, composition, and optical properties of both the expansion and seed regions. XRD and Raman spectroscopy indicate no significant differences in crystallization quality between the expansion and seed regions. XPS and photoluminescence characterizations reveal that the light yellow color of the seed region is mainly due to $$V_{Al}$$ V Al defects. In contrast, the deeper yellow color in the expansion region is caused by $$V_{Al}$$ V Al –$$O_N$$ O N complex defects. Additionally, etching results exhibit a polarity reversal from the Al-polar to N-polar growth face in localized chromatic aberration region. The bonding angle of approximately $${90}^\circ$$ 90 ∘ at the $$B_{1}$$ B 1 bond (formation by the half-filled orbitals of the Al and N atoms) site, which occurs during the bonding of Al and N atoms, results in the polarity reversal during m-plane lateral growth. This work provides implications for the preparation of large-sized AlN single crystals.

Unveiling the importance of controllable growth of c-axis oriented Sn-doped ZnO nanorod arrays: towards humidity sensing applications

In this study, tin (Sn)-doped zinc oxide (ZnO) nanorod arrays (SZO) were prepared using a sonication assisted sol-gel immersion method, with the growth of the nanorod arrays controlled by varying the immersion time in the precursor material. Morphology images taken using a Field Emission Scanning Electron Microscope (FESEM) demonstrated an enlargement of the average diameter of the nanorod arrays from 55 nm at 5 min immersion to 122 nm at 200 min immersion. The cross-sectional and surface elemental analysis showed that the sample immersed for 60 min has the highest detection of Sn, with a bulk concentration of 1.8 at.% and surface concentration of 1 at.%. Interestingly, we noticed that Sn is not exist on the surface of 200 min immersion, indicating the depletion of the Sn precursor due to the prolongation of the immersion time. From the current voltage (I-V) analysis, 60 min immersion sample generated the lowest thin film resistivity, which engendered the best humidity sensitivity of 4.05. This study demonstrated the significant importance of optimizing the immersion or growth time for doped 1-D nanostructures to obtain the best humidity sensing performance.

GP VI-Mediated Platelet Activation and Procoagulant Activity Aggravate Inflammation and Aortic Wall Remodeling in Abdominal Aortic Aneurysm.

Platelets play an important role in cardiovascular and cerebrovascular diseases. Abdominal aortic aneurysm (AAA) is a highly lethal, atherosclerosis-related disease with characteristic features of progressive dilatation of the abdominal aorta and degradation of the vessel wall, accompanied by chronic inflammation. Platelet activation and procoagulant activity play a decisive role in the AAA pathology as they might trigger AAA development in both mice and humans. The present study investigated the impact of the major platelet collagen receptor GP (platelet glycoprotein) VI in pathophysiological processes underlying AAA initiation and progression. For experimental AAA induction in mice, PPE (porcine pancreatic elastase) and the external PPE model were used. Genetic deletion of GP VI offered protection of mice against aortic diameter expansion in experimental AAA. Mechanistically, GP VI deficiency resulted in decreased inflammation with reduced infiltration of neutrophils and platelets into the aortic wall. Furthermore, remodeling of the aortic wall was improved in the absence of GP VI, as indicated by reduced MMP (matrix metalloproteinase)-2/9 and OPN (osteopontin) plasma levels and an enhanced α-SMA (α-smooth muscle actin) content within the aortic wall, accompanied by reduced cell apoptosis. Consequently, an elevation in intima/media thickness and elastin content was observed in GP VI-deficient PPE mice, resulting in a significantly reduced aortic diameter expansion and reduced aneurysm incidence. In patients with AAA, enhanced plasma levels of soluble GP VI and fibrin, as well as fibrin accumulation within the intraluminal thrombus might serve as new biomarkers to detect AAA early. Moreover, we hypothesize that GP VI might play a role in procoagulant activity and thrombus stabilization via binding to fibrin. In conclusion, our results emphasize the potential need for a GP VI-targeted antiplatelet therapy to reduce AAA initiation and progression, as well as to protect patients with AAA from aortic rupture.

Numerical study on structural design and mechanical analysis of anti-migration tracheal stent with non-uniform Poisson's ratio

Stent migration is one of the common complications after tracheal stent implantation. The causes of stent migration include size mismatch between the stent and the trachea, physiological movement of the trachea, and so on. In order to solve the above problems, this study designed a non-uniform Poisson ratio tracheal stent by combining the size and structure of the trachea and the physiological movement of the trachea to improve the migration of the stent, meanwhile ensuring the support of the stent. In this study, the stent corresponding to cartilage was constructed with negative Poisson's ratio, and the stent corresponding to the circular connective tissue and muscular membrane was constructed with positive Poisson's ratio. And four kinds of non-uniform Poisson's ratio tracheal stents with different link lengths and negative Poisson's ratio were designed. Then, this paper numerically simulated the expansion and rebound process of the stent after implantation to observe the support of the stent, and further simulated the stretch movement of the trachea to calculate the diameter changes of the stent corresponding to different negative Poisson's ratio structures. The axial migration of the stent was recorded by applying different respiratory pressure to the wall of the tracheal wall to evaluate whether the stent has anti-migration effect. The research results show that the non-uniform Poisson ratio stent with connecting rod length of 3 mm has the largest diameter expansion in the negative Poisson ratio section when the trachea was stretched. Compared with the positive Poisson's ratio structure, the axial migration during vigorous breathing was reduced from 0.024 mm to 0.012 mm. The negative Poisson's ratio structure of the non-uniform Poisson's ratio stent designed in this study did not fail in the tracheal expansion effect. Compared with the traditional stent, the non-uniform Poisson's ratio tracheal stent has an anti-migration effect under the normal movement of the trachea while ensuring the support force of the stent.

Reducing Laser Exposure Time of PBF-LB/P by Providing High Energy Without Thermal Degradation and Its Effect on Part Strength and Process Time

Abstract One of the most promising additive manufacturing technologies for the production of end-use parts is powder bed fusion of polymer with laser beam (PBF-LB/P). This technology can reduce production costs by increasing process efficiency and production speed. As PBF-LB/P is a layer-wise additive manufacturing process, the production speed can be increased by reducing the layering time. Although some operations such as recoating are performed during the layering process, considerable time is spent on laser scanning. To reduce the laser exposure time while maintaining proper powder melting, a high-power beam should be irradiated to the powder layer to prevent energy shortage. However, as the laser beam power increases, the irradiance at the beam center increases significantly, causing powder degradation such as thermal decomposition or sublimation. In this study, an appropriate input energy range was determined by obtaining an input energy limit that does not cause powder deterioration via experimental observations and temperature estimations during the process. Furthermore, the influence of the scanning parameters on the mechanical properties of built specimens was investigated to reduce the layering time within an indicated range. Results show that the mechanical strength of the built parts decreases slightly as the scan spacing increases following the expansion of the beam diameter. This study also validated the effects of scanning parameters on layering time. As a result, by doubling the scan speed and spacing, the layering time can be reduced by up to 1/3.

Preparation and carrier preference of synergistic antibacterial cetylpyridinium/Cu2+/halloysite composite

By employing halloysite (Hal) as the carrier, a synergistic cetylpyridinium (CP+)/Cu2+/Hal (PCH) system was constructed via a vacuum loading method. Hal’s lumen serves as a storage “container” for CP+ and Cu2+, achieving their optimized thermal stability and “burst + sustained” release. Antibacterial agents’ loading makes PCH tend to hydrophobicity and exhibit synergistic antibacterial efficacy. With the released antibacterial agents and adsorbed PCH particles, 100 % of Staphylococcus aureus and Escherichia coli are inactivated by PCH in 120 min at concentrations of 20 mg/L and 150 mg/L, respectively. The effect of Hal’s tubular structure on PCH’s performance shows that the shortening of Hal’s nanotube and the expansion of lumen diameter with the preservation of intact tubular structure can intensify the loading-release and antibacterial process of CP+ and Cu2+. However, it requires balancing the demands of rapid bactericidal and durable antibacterial activity. The obtained PCH is well dispersed and compatible with thermoplastic polyurethane, enhancing its mechanical properties. The composite film containing 10 wt% PCH inactivates 100 % Staphylococcus aureus and 98.5 % Escherichia coli in 4 h, while exhibiting excellent elongation at break (274.3 %) and tensile strength (40.7 MPa). Therefore, the developed PCH holds promise for manufacturing antibacterial functional products to combat bacterial infections.

Outcomes of Watchful Waiting Strategy and Predictors of Postoperative Prognosis in Asymptomatic or Equivocally Symptomatic Chronic Severe Aortic Regurgitation With Preserved Left Ventricular Function.

The optimal surgical timing for asymptomatic or equivocally symptomatic chronic severe aortic regurgitation with preserved left ventricular ejection fraction remains controversial. Two hundred ten consecutive patients (median age 65 years) with asymptomatic or equivocally symptomatic chronic severe aortic regurgitation and left ventricular ejection fraction ≥50% were registered. First, the treatment plans (aortic valve replacement or watchful waiting) after initial diagnosis were investigated. Then, 2 studies were set: Study A (n=144) investigated the prognosis of patients who were managed under the watchful waiting strategy after initial diagnosis; Study B (n=99) investigated the postoperative prognosis in patients who underwent aortic valve replacement at initial diagnosis or after watchful waiting. The primary outcomes were all-cause death in Study A and postoperative cardiovascular events in Study B. In Study A, 3 died of noncardiovascular causes during a median follow-up of 3.2 years. In Kaplan-Meier analysis, the survival curve was similar to that of an age-sex-matched general population in Japan. In Study B, 9 experienced the primary outcome during a median follow-up of 5.0 years. In Cox regression analysis, preoperative left ventricular end-systolic diameter enlargement (hazard ratio, 1.11; P=0.048) and left ventricular end-systolic diameter >45 mm (hazard ratio, 12.75; P=0.02) were significantly associated with poor postoperative prognosis. In Kaplan-Meier analysis, left ventricular end-systolic diameter >45 mm predicted a higher risk of the primary outcome (P <0.01). Watchful waiting was achieved safely in asymptomatic or equivocally symptomatic chronic severe aortic regurgitation with preserved left ventricular ejection fraction. Preoperative left ventricular end-systolic diameter >45 mm predicted a poor postoperative outcome and may be an optimal cut-off value for surgical indication.

Impact of Intraoperative Branch Embolization for Type 2 Endoleak Prevention During Endovascular Abdominal Aortic Repair

Endovascular abdominal aortic repair (EVAR) has a significantly higher revision rate than open repair, primarily due to type 2 endoleak (2EL). Although 2ELs are considered benign, late open conversion (LOC) due to the expansion of the aneurysm diameter of the 2EL is a concern in the mid- and long-term. In this study, we investigated the impact of embolization of the inferior mesenteric artery (IMA) or lumbar artery (LA) at the time of the initial EVAR and its long-term outcomes. Between April 2008 and December 2021, 743 EVAR procedures for abdominal aortic aneurysms were performed at our institution. The patients were divided into 2 groups at the time of initial surgery, namely, 215 and 528 patients in the embolization (Group E) and nonembolization (Group N) groups, respectively. Branch embolization was performed in patients with an IMA diameter ≥3mm and LA diameter ≥2mm on preoperative computed tomography. Re-embolization with EL was performed in patients with a diameter enlargement ≥10mm, and LOC was performed in patients with continued enlargement ≥15mm after re-embolization. The mean follow-up period was 7.0years. The mean number of branch embolizations was 2.3±1.1. Intraoperatively, the operative time, fluoroscopy time, irradiation dose, and contrast medium use were significantly higher in Group E than in Group N. There was a significant difference between the 2 groups regarding shrinkage (Group E versus Group N: 45.6% versus 37.3%; P=0.03) and enlargement (Group E versus Group N: 9.3% vs. 19.5%; P<0.001) of the aneurysm diameter by>5mm after EVAR. In the mid- and long-term, the avoidance rate of 2EL reintervention was significantly lower in Group E at 5years (93.5% vs. 88.6%) and 10years (87.5% vs. 76.4%; P=0.04). LOC prevention was 5years; Group E: 100% vs. 96.9% for Group N and 10years; Group E: 98.8% vs. 92.5% for Group N, significantly lower in Group E (P=0.02). The impact of branch embolization at the time of the initial EVAR is believed to prevent enlargement of the aneurysmal sac and LOC. However, prolonged operation time, increased radiation exposure, and the use of contrast medium have been debated. To improve the long-term results of EVAR, embolisms of both the IMA and LA are required.

A case of salvage surgery following chemoradiotherapy and durvalumab for initially unresectable superior sulcus tumor with N3 involvement

BackgroundDurvalumab after chemoradiation (PACIFIC regimen) provides favorable treatment outcomes for unresectable stage III non-small cell lung cancer (NSCLC). The feasibility of salvage surgery after the PACIFIC regimen has been reported in some studies; however, its efficacy remains unclear. We herein present the first case of salvage surgery after the PACIFIC regimen for a superior sulcus tumor with N3 involvement, in which a pathological complete response was achieved.Case presentationA 53-year-old man with a left superior sulcus tumor with N3 (# 1L, #4R) involvement (adenocarcinoma, clinical T3N3M0/IIIC) underwent concurrent chemoradiotherapy (2 cycles of cisplatin plus vinorelbine with 60 Gy radiotherapy) followed by durvalumab treatment for 1 year at a previous hospital. The PACIFIC regimen provided a significant primary tumor shrinkage (diameter 3.1 cm to 0.5 cm) with the disappearance of 18F-fluorodeoxyglucose uptake in all nodes. Six months after the end of the PACIFIC regimen, only the primary tumor showed enlargement (diameter 0.5 cm to 2.0 cm). Accordingly, local tumor recurrence was suspected. Salvage surgery (left upper lobectomy with combined chest wall resection [1st to 4th rib]) was performed. The histological examination revealed no viable tumor cells (ypT0N0M0). At 7 months after salvage surgery, the patient remains alive with no signs of tumor recurrence.ConclusionsThe present case suggests that salvage surgery may be feasible after the PACIFIC regimen for superior sulcus tumors. A long-term follow-up is essential to determine the efficacy of salvage surgery.

Mitigation of flow-induced vibrations in high-speed flows using triply periodic minimal surface structures

Flow-induced vibrations (FIVs) pose challenges and limit intended functionalities in many industrial sectors, especially in high-tech industries such as semiconductor manufacturing. Because of extreme precision requirements, any mechanical perturbation to the manufacturing process detrimentally affects production quality and process yield. The impact of FIV must, thus, be minimized. This study investigates the FIV reducing properties of triply periodic minimal surface (TPMS) inserts in industrial cooling systems by expanding the Darcy–Forchheimer model for flow through porous media to a turbulent regime. Using the expanded model, we performed full-scale finite-element simulations for high-speed flows in a pipe with an abrupt expansion of diameter and analyzed the effects of TPMS inserts on the reduction of induced turbulence and FIV. Our data revealed that the TPMS inserts exhibit promising characteristics for FIV mitigation revealing up to 97.6% reduction in turbulent kinetic energy and 32.7% reduction in vorticity. These results complement available data on using TPMS inserts to eliminate geometry-induced instabilities in internal pipe flows.

Growing simplicial complex with face dimension selection and preferential attachment.

When simplicial complexes are used to represent higher-order systems, information regarding when and how interactions happen may be lost. In this paper, we propose the concept of temporal simplicial complexes, in which simplices with timestamps (or temporal simplices) are used to represent interactions, and faces with weights are used to represent relations. Then, we propose a growing model with two rules, face dimension selection (FDS), and preferential attachment. By properly setting the probability parameter vector q in the FDS rule, one can balance network diameter expansion and network centrality, thus attaining more flexibility in the growing process. Our theoretical analysis and simulations that followed show the generalized degree of faces of any dimension follows a power-law distribution, with a scaling component controlled by q. Our work provides a flexible growing model and can be used to study higher-order systems with temporal properties.

Computational Fluid Dynamics investigation of the impact of 6% crept pressure tubes on flow behaviour, fuel temperature, and pressure tube wall temperature of a single CANDU 37M fuel bundle

CANDU nuclear generating stations experience aging effects that affect the reactor operation, including pressure tube deformation (i.e., diametral expansion, sag, and elongation). The diametral expansion of the pressure tube will alter coolant flow behaviour, which will impact CANDU fuel and pressure tube temperatures, thereby directly affecting the reactor’s operational performance and safety margins. However, these impacts are not yet fully understood at this point. In this study, two Computational Fluid Dynamics simulations were conducted with STAR CCM+ on a single CANDU Modified 37-element (37M) fuel bundle placed in both non-crept and 6% crept pressure tubes under normal operating conditions. The predicted coolant flow behaviour, fuel temperatures, and pressure tube wall temperatures were compared between both cases to predict the impact of diametral expansion on these aspects. The results indicate that approximately 29% of the coolant flow bypasses the bundle in the 6% crept pressure tube, leading to a reduction of up to 25% in subchannel flow velocity and a maximum increase of 36.7 K in fuel maximum temperature. Both the non-crept and 6% crept pressure tube wall temperature profiles were found to be asymmetric with respect to the bundle’s horizontal axis. The temperature at the bottom of the pressure tube is relatively higher than at the top in the non-crept case, while the temperature difference is noticeably greater in the 6% crept case.

Risk factors for proximal and distal aortic events after type A acute aortic dissection.

Type A acute aortic dissection (TAAAD) is a life-threatening condition often requiring emergency surgery, with approximately 30% of patients needing reoperation. This study aimed to identify predictors of long-term aortic events from early postoperative computed tomography (CT) examinations. A total of 336 cases underwent TAAAD surgery at two institutions between 2002 and 2018. Of these, 302 patients received CT examinations immediately after initial TAAAD surgery. Predictors of aortic events were evaluated from these early postoperative CT exams. Aortic events were defined as any events involving aortic-related death, open surgery, reoperation, endovascular stenting, or thoracic aorta diameter enlargement to ≥ 55mm. Excluding 34 in-hospital deaths (10.1%; 34/336), the 1-, 5-, and 10-year actuarial survival rates after primary TAAAD surgery were 98.2%, 88.6%, and 81.7%, respectively. Over a mean follow-up period of 7.4 ± 5.1years, 67 aortic events (proximal: 19, distal: 45, both: 3) were observed. Freedom from proximal aortic events was 98.6%, 93.9%, and 85.2% at 1, 5, and 10years, respectively. Proximal anastomosis new entry was identified as a significant risk factor for aortic events, with a 92% vs. 42% incidence at 10years (p < 0.001). Freedom from distal aortic events was 99.6%, 84.5%, and 67.2% at 1, 5, and 10years, respectively. A false/true area ratio greater than 1 and distal anastomosis new entry were significant risk factors for aortic events (low-risk group: 83.3% vs. high-risk group: 42.3% at 10years, p < 0.001). Detailed analysis of early postoperative CT scans following primary TAAAD surgery may help identify predictors of subsequent aortic events, potentially improving long-term patient management and outcomes.

Structural reconstruction of mouse acute aortic dissection by intravenously administered human Muse cells without immunosuppression

BackgroundStanford type B-acute aortic dissection (type B-AAD) is often life-threatening without invasive surgery. Multilineage-differentiating stress enduring cell (Muse cells), which comprise several percent of mesenchymal stem cells (MSCs), are endogenous pluripotent-like stem cells that selectively home to damaged tissue and replace damaged/apoptotic cells by in-vivo differentiation.MethodsMortality, aortic diameter expansion, cell localization, cell differentiation, and inflammation of the dissected aorta were evaluated in type B-AAD model mice intravenously injected with human-Muse cells, -elastin-knockdown (KD)-Muse cells, -human leukocyte antigen-G (HLA-G)-KD-Muse cells, or MSCs, all without immunosuppressant.ResultsHere, we show the Muse (50,000 cells) group has a lower incidence of aortic rupture and mortality of AAD compared with the MSC-50K (50,000 human-MSCs) and vehicle groups. Spectrum computed tomography in-vivo dynamics and 3-dimensional histologic analyses demonstrate that Muse cells more effectively home to the AAD tissue and survive for 8 weeks in the Muse group than in the MSC-750K (750,000 human-MSCs containing 50,000 Muse cells) group. Homing of Muse cells is impeded in the HLA-G-KD-Muse (50,000 cells) group. Differentiation of homed Muse cells into CD31(+) and alpha-smooth muscle actin (+) cells, production and reorganization of elastic fibers in the AAD tissue, and suppression of diameter expansion are greater in the Muse group than in the MSC-750K and elastin-KD-Muse (50,000 cells) groups.ConclusionsIntravenously administered Muse cells reconstruct the dissected aorta and improve mortality and diameter enlargement rates. Moreover, small doses of purified Muse cells are more effective than large doses of MSCs. HLA-G is suggested to contribute to the successful survival and homing of Muse cells.

Myocardial work in idiopathic premature ventricular contractions: Assessing left ventricular function and prognosis.

Premature ventricular contractions (PVCs) can lead to impairment of left ventricular function. The noninvasive myocardial work technique, which incorporates left ventricular afterload, represents a new method for assessing left ventricular functional. The aim of this study is to explore the value of noninvasive myocardial work technique in assessing left ventricular systolic function in patients with PVCs. Compare the clinical data, two-dimensional echocardiography parameters, and myocardial work parameters of 66 patients with PVCs and 35 healthy volunteers and explore the relevant risk factors for postoperative recurrence in patients with PVCs. In patients with PVCs compared to the control group, they exhibit enlargement of left atrial diameter (LAD) and left ventricular internal dimension in diastole (LVIDd), as well as thickening of the left ventricular wall. The global work waste (GWW) increases, while the global work efficiency (GWE) decreases. There is a significant negative correlation between the PVC burden and GWE (r = -0.70, p <0.01), and a significant positive correlation between the PVC burden and GWW (r = 0.58, p <0.01). GWE is a sensitive indicator for predicting the recurrence of PVCs after radiofrequency ablation. Patients with GWE <91.5%, global longitudinal strain (GLS) <15.5%, and ejection fraction (EF) <62.5% have a higher postoperative recurrence rate. PVCs can cause impairment of left ventricular systolic function. GWE is the most sensitive indicator for predicting postoperative recurrence in patients with PVCs. Patients with GWE <91.5%, GLS <15.5%, and EF <62.5% have a higher postoperative recurrence rate.

Coronary Artery Aneurysm or Ectasia as a Form of Coronary Artery Remodeling: Etiology, Pathogenesis, Diagnostics, Complications, and Treatment.

Coronary artery aneurysm or ectasia (CAAE) is a term that includes both coronary artery ectasia (CAE) and coronary artery aneurysm (CAA), despite distinct phenotypes and definitions. This anomaly can be found in 0.15-5.3% of coronary angiography. CAE is a diffuse dilatation of the coronary artery at least 1.5 times wider than the diameter of the normal coronary artery in a patient with a length of over 20 mm or greater than one-third of the vessel. CAE can be further subdivided into diffuse and focal dilations by the number and the length of the dilated vessels. Histologically, it presents with extensive destruction of musculoelastic elements, marked degradation of collagen and elastic fibers, and disruption of the elastic lamina. Conversely, CAA is a focal lesion manifesting as focal dilatation, which can be fusiform (if the longitudinal diameter is greater than the transverse) or saccular (if the longitudinal diameter is smaller than the transverse). Giant CAA is defined as a 4-fold enlargement of the vessel diameter and is observed in only 0.02% of patients after coronary. An aneurysmal lesion can be either single or multiple. It can be either a congenital or acquired phenomenon. The pathophysiological mechanisms responsible for the formation of CAAE are not well understood. Atherosclerosis is the most common etiology of CAAE in adults, while Kawasaki disease is the most common in children. Other etiological factors include systemic connective tissue diseases, infectious diseases, vasculitis, congenital anomalies, genetic factors, and idiopathic CAA. Invasive assessment of CAAE is based on coronary angiography. Coronary computed tomography (CT) is a noninvasive method that enables accurate evaluation of aneurysm size and location. The most common complications are coronary spasm, local thrombosis, distal embolization, coronary artery rupture, and compression of adjacent structures by giant coronary aneurysms. The approach to each patient with CAAE should depend on the severity of symptoms, anatomical structure, size, and location of the aneurysm. Treatment methods should be carefully considered to avoid possible complications of CAAE. Simultaneously, we should not unnecessarily expose the patient to the risk of intervention or surgical treatment. Patients can be offered conservative or invasive treatment. However, there are still numerous controversies and ambiguities regarding the etiology, prognosis, and treatment of patients with coronary artery aneurysms. This study summarizes the current knowledge about this disease's etiology, pathogenesis, and management.

Prevalence and associated factors of atrial fibrillation among patients with rheumatic heart disease attending public referral hospitals in Bahir Dar city, Northwest Ethiopia, 2023

BackgroundAtrial fibrillation (AF) is a supraventricular arrhythmia associated with uncoordinated atrial activation. Atrial fibrillation is complication of rheumatic heart disease and is associated with substantial morbidity and mortality. It is a growing public health problem and economic and social burden. Studies investigating the prevalence and factors associated with atrial fibrillation among chronic rheumatic heart disease patients in Ethiopia are scarce. Therefore, this study aimed to determine the prevalence and factors associated with atrial fibrillation in patients with chronic rheumatic heart disease.Methods and materialsA hospital-based cross-sectional study was conducted. A total of 410 patients were selected using a systematic random sampling method. The data were entered into Epi-Data version 4.6 and subsequently exported to SPSS version 26 software for analysis. A binary logistic regression model was applied to identify significant variables related to AF.ResultsIn this study, 410 patient charts were reviewed. The prevalence of atrial fibrillation was 43% (95% CI of 38% up to 48%). Male (AOR = 3.81, 95% CI 2.00-7.26), age greater than 30 years (AOR = 7.26, 95% CI 3.93–13.41), heart failure (AOR = 4.65, 95% CI 2.39–9.04), mitral valve stenosis (AOR = 6.36, 95% CI 2.92–13.87), and left atrial diameter enlargement (AOR = 3.41, 95% CI 1.64–7.09) were associated with atrial fibrillation.Conclusions and recommendationsAtrial fibrillation leads patients to frequent hospital admission and increases hospital mortality. As a result, health care professionals need to pay more attention to and apply more clinical treatment for older patients, those with heart failure, those with mitral valve stenosis, and those with left atrial diameter enlargement-associated causes of atrial fibrillation.

Daily trunk radial growth patterns in relation to precipitation in orange trees in the dry-hot valley region of Southwest China

The dry-hot valley regions of Southwest China suffer droughts and high temperatures coexist environment. The efficient use of rainfall makes it possible for plants to safely cope with the environmental stress in the region. To reveal the driving mechanism of rainfall on typical tree secondary growth, orange tree (Citrus sinensis L. Osbeck), the commonly grown economic tree in the region was selected. Trunk diameter, sap flow, leaf humidity, meteorological conditions and soil water content were simultaneously monitored for the 2020–2022 period. Based on frequency distribution of trunk diameter changes data, trunk diameter changes were classified into positive growth (dramatic expansion, and common expansion), and negative growth (dramatic shrinkage, and common shrinkage) types. Furthermore, the relationships among the different growth patterns and rainfall or drought events were analyzed. The results showed: i) Trunk diameter maintained positive growth on rainy days, whereas both positive and negative growth occurred on rainless days. Although rainy period was not frequent, a high proportion of the total growth occurred during that time. ii) The common expansion type with a high frequency contributed to approximately 30% of the total growth, whereas the dramatic expansion type with a low frequency contributed to approximately 70% of the total growth. iii) There was a highly significant correlation between dramatic tree diameter expansion and rainfall. iv) Cumulative growth in tree diameter during rainy period was significantly driven by the duration of rainfall, the wetting time of leaf and the amount of rainfall. v) Compared with rainfall amount, the time rainfall related indexes were more closely related with tree dramatic diameter expansion. vi) While increasing soil water content and dry air mitigation due to rainfall enhanced average growth, it concurrently suppressed negative growth of tree trunk diameter after rainfall. The study confirmed that rainfall was critical for tree diameter growth in dry-hot valley regions of Southwest China. Relevant results are beneficial for improving understanding of plant precipitation utilization mechanism and could provide useful information on extreme meteorological hazards assessment in the context of climate change.

Assessment of a body force modeling approach to examine the aerodynamics of high bypass ratio fan stages

The primary focus of modern civil jet engine intake design is to enhance propulsive efficiency through an increase in the bypass ratio of the turbofan engine, which requires an enlargement in fan diameter. However, this enlargement results in increased weight and drag due to the need for a larger nacelle to surround the fan. To mitigate these issues, efforts are being made to shorten the axial length of the aircraft engine intakes. Nonetheless, this reduction leads to more vulnerable fan aerodynamics since the diffusion within the intake must occur over a shorter distance, causing a higher possibility of flow separation. Common intake design methods employ throughflow nacelle models that do not consider the aerodynamic effects of the fan, including blockage, mass flow redistribution, and suction. The utilization of a full annulus domain numerical setup, which is necessary to capture inlet distortions, demands excessive computational resources particularly during the design phase. As a result, reduced order models, such as the body force model, can be utilized to simulate fan intake aerodynamics. This paper will assess the body force model and its abilities by comparing conventional bladed single passage simulations with the body force approach.