Differences In Wall Thickness Research Articles

Clinical and diagnostic value of transrectal ultrasound in assessing the severity of ulcerative colitis

Background. Endoscopic and histological studies play a decisive role in the diagnosis of inflammatory bowel diseases, as they allow confirming the diagnosis, determining the degree of inflammatory activity, the extent of intestinal damage, and monitoring the course of disease and the effectiveness of therapy. Howe­ver, it is not possible to assess the state of all intestinal layers with colonoscopy. Modern non-invasive methods such as ultrasound, computed tomography, and magnetic resonance imaging cope best with this purpose. With their help, you can assess the state of the intestinal wall and obtain a cross-sectional image of the intestine, evaluate extraintestinal structures (lymph nodes, vessels, fatty tissue). It can be said that endoscopy and ultrasound search for the same type of information but look at different things. Deepening the knowledge about the role of ultrasound of the distal parts of the colon in ulcerative colitis (UC) will contribute to the improvement of diagnosis, development of methods for determining the activity of UC, control of therapy, which will allow optimizing the choice of adequate treatment measures. The goal of the work: to improve the diagnosis of ulcerative colitis based on the study of ultrasonographic parameters of the rectum. Materials and methods. Transrectal ultrasound was performed on an expert-class SonoScape S60 ultrasound scanner using a low-frequency convex probe of 3.5 MHz and a rectovaginal convex probe of 6 MHz. Transperineal and transrectal approaches were used. Results. Wall thickness and submucosal thickness differed significantly in moderate and severe UC. Analysis of transrectal ultrasound indicators depending on the endoscopic activity of the UC revealed no significant differences in the rectal wall thickness. But there was a tendency to increase in the thickness of the mucous layer and the coefficient of deformation with increasing endoscopic activity. Most patients had an increase in the degree of blood flow density, which depended on the disease severity. During the regression analysis, a relationship was found between the intestinal wall thickness (r = 0.44; p = 0.0121) and submucosal layer thickness (r = 0.86; p = 0.006) with the Mayo index. A correlation was revealed between the thickness of the colon wall and the frequency of bowel movements (r = 0.37; p = 0.018), leukocytosis (r = 0.38; p = 0.016) and erythrocyte sedimentation rate (r = 0.35; p = 0.027). The blood flow density in the intestinal wall positively correlated with the presence of edema (r = 0.32; р = 0.045), the severity of the vascular pattern (r = 0.42; р = 0.008), the presence of erosions (r = 0.4; р = 0.011) and bleeding of the mucous membrane (r = 0.50; p = 0.001). The coefficient of deformation positively correlated with the presence of flatulence (r = 0.35; р = 0.048). Conclusions. Endoscopic exa­mination in patients with UC should be supplemented with transrectal ultrasound. A correlation was found between the intestinal wall thickness and the thickness of the submucosal layer in patients with UC and the Mayo index. A tendency to increase in the thickness of the mucous layer and the coefficient of deformation with increasing endoscopic activity was determined. Relationships between endoscopic and ultrasound parameters can be used to assess disease activity.

Multi-Objective Optimization of a Multi-Cavity, Significant Wall Thickness Difference Extrusion Profile Mold Design for New Energy Vehicles.

With the rapid development of the new energy vehicle market, the demand for extruded profiles for battery trays, mainly characterized by significant wall thickness differences in multiple chambers, is increasing, posing new challenges to production and quality control. This study examines the multi-objective optimization problem in the design process of aluminum profile dies with multi-cavity profiles and significant wall thickness differences. Using QFORM-extrusion professional aluminum extrusion finite element analysis software and the response surface analysis method, the standard deviation of the velocity (SDV), standard deviation of the pressure (SDP), and thick wall hydrostatic pressure (TWHP) on the profile section at the die exit are optimized. By analyzing the functional relationship between the key die structure parameters (the height of the baffle plates, the length of the bearing, and the height of the false mandrel) and the optimization objective, the optimal combination scheme of die structure parameters was obtained using the NSGA2 (non-dominated sorting genetic algorithm-2) multi-objective genetic optimization algorithm. The results show that, compared with the initial design scheme, the standard deviation of profile section velocity was reduced by 5.33%, the standard deviation of pressure was reduced by 11.16%, and the thick wall hydrostatic pressure was increased by 26.47%. The die designed and manufactured using this scheme successfully completed the hot extrusion production task, and the profile quality met the predetermined requirements, thus verifying the effectiveness of this study in optimizing the design of a multi-cavity aluminum profile die with significant differences in wall thickness for complex structures.

Bulked Segregant RNA-Seq Reveals Different Gene Expression Patterns and Mutant Genes Associated with the Zigzag Pattern of Tea Plants (Camellia sinensis).

The unique zigzag-patterned tea plant is a rare germplasm resource. However, the molecular mechanism behind the formation of zigzag stems remains unclear. To address this, a BC1 genetic population of tea plants with zigzag stems was studied using histological observation and bulked segregant RNA-seq. The analysis revealed 1494 differentially expressed genes (DEGs) between the upright and zigzag stem groups. These DEGs may regulate the transduction and biosynthesis of plant hormones, and the effects on the phenylpropane biosynthesis pathways may cause the accumulation of lignin. Tissue sections further supported this finding, showing differences in cell wall thickness between upright and curved stems, potentially due to lignin accumulation. Additionally, 262 single-nucleotide polymorphisms (SNPs) across 38 genes were identified as key SNPs, and 5 genes related to zigzag stems were identified through homologous gene function annotation. Mutations in these genes may impact auxin distribution and content, resulting in the asymmetric development of vascular bundles in curved stems. In summary, we identified the key genes associated with the tortuous phenotype by using BSR-seq on a BC1 population to minimize genetic background noise.

Effect of local loading on microstructure and enhanced mechanical property of large complex castings prepared by Al–Si–Fe–Mn–Mg–Cu alloy during squeeze casting

Flywheel shells with a complex structure and large wall-thickness difference, as key components in heavy trucks, serve to connect the engine and transmission. Formability and mechanical performance control of such components should be taken into consideration. In this work, an Al–Si–Fe–Mn–Mg–Cu alloy was used to manufacture the flywheel shell via squeeze casting. The role of local loading on microstructure and mechanical property at thick-walled positions was investigated. Furthermore, the effect of the squeeze casting specific pressure and heat treatment on the microstructure and mechanical property of the Al–Si–Fe–Mn–Mg–Cu alloy flywheel shells was also analyzed. The results showed that at the thick-walled positions, local loading not only helped eliminate the solidification defects, but also refined the microstructure including α-Al grains and secondary dendrite arm spacing. With increasing the squeeze casting specific pressure from 24 MPa to 32 MPa, microstructure refinement and mechanical property enhancement of squeeze casting flywheel shells were obtained. After T6 heat treatment, the yield strength and ultimate tensile strength of flywheel shells were further increased to 261.8 and 318.4 MPa, respectively, owing to the formation of spherical eutectic Si phases and nano-sized β'', Q and S precipitates.

Advanced maternal age alters cardiac functional and structural adaptations to pregnancy in rats.

A significant number of pregnancies occur at advanced maternal age (>35 yr), which is a risk factor for pregnancy complications. Healthy pregnancies require massive hemodynamic adaptations, including an increased blood volume and cardiac output. There is growing evidence that these cardiovascular adaptations are impaired with age, however, little is known about maternal cardiac function with advanced age. We hypothesized that cardiac adaptations to pregnancy are impaired with advanced maternal age. Younger (4 mo; ∼early reproductive maturity in humans) and aged (9 mo; ∼35 yr in humans) pregnant Sprague-Dawley rats were assessed and compared with age-matched nonpregnant controls. Two-dimensional echocardiographic images were obtained (ultrasound biomicroscopy; under anesthesia) on gestational day 19 (term = 22 days) and compared with age-matched nonpregnant rats (n = 7-9/group). Left ventricular structure and function were assessed using short-axis images and transmitral Doppler signals. During systole, left ventricular anterior wall thickness increased with age in the nonpregnant rats, but there was no age-related difference between the pregnant groups. There were no significant pregnancy-associated differences in left ventricular wall thickness. Calculated left ventricular mass increased with age in nonpregnant rats and increased with pregnancy only in young rats. Compared with young pregnant rats, the aortic ejection time of aged pregnant rats was greater and Tei index was lower. Overall, the greater aortic ejection time and lower Tei index with age in pregnant rats suggest mildly altered cardiac adaptations to pregnancy with advanced maternal age, which may contribute to adverse outcomes in advanced maternal age pregnancies.NEW & NOTEWORTHY We demonstrated that even before the age of reproductive senescence, rats show signs of age-related alterations in cardiac structure that suggests increased cardiac work. Our data also demonstrate, using an in vivo echocardiographic approach, that advanced maternal age in a rat model is associated with altered cardiac function and structure relative to younger pregnant controls.

Effect of the Flow Curve Determination on the Thinning of Drawn Parts

This study presents the results of finite element simulations based on different variations of the flow curve of DC04 automotive thin sheet. The aim of our research is to investigate how different flow curve equations affect the variation of sheet thickness in cup drawing tests. In order to exclude other influencing factors in the experiment, both the sheet material and the geometric properties of the specimen, as well as the external state factors were considered to be the same in all cases. The finite element simulations were performed using Simufact 2021.1 software. Our results shows that there are no significant differences in wall thicknesses until we reach the zone of double necking, where essential differences are observed.

Effect of Local Pressurization on Microstructure and Mechanical Properties of Aluminum Alloy Flywheel Housing with Complex Shape.

In this work, squeeze casting experiments of flywheel housing components with a large wall thickness difference and a complex shape were carried out with AlSi9Mg aluminum alloy. The defects, microstructures, and mechanical properties under different process parameters were investigated. Furthermore, the local pressurization process was applied to the thick-walled positions to force-feed the cast defects. The mechanical properties and microstructures at these positions were analyzed. The results showed that the surface quality of formed components was good and that local pressurization could effectively reduce the shrinkage cavity and shrinkage porosity in thick walls, but the scope and effect of forced feeding were limited. The optimum process parameters were a pouring temperature of 650 °C, a specific pressure of 48 MPa, a mold temperature of 220 °C, a local pressurization of 800 MPa, and pressure delay times of 15 s (side A) and 17 s (side B). The ultimate tensile strength, yield strength, and elongation of the formed component under validation experiments of the optimum process parameters were 201 MPa, 103 MPa, and 5.1%. Meanwhile, the fine grains of primary α-Al were mainly rosette and equiaxed grains, and the average grain size was about 40 μm. The microstructure of the eutectic silicon was acicular and was prone to segregation under pressure. According to profile morphology, the positions after pressurization were divided into a deformation zone, a direct action zone, and an indirect action zone. The coexistence of as-cast and plastic deformation microstructures was observed. The effect of local pressurization mainly involved a change in the solidification process, plastic deformation, and forced feeding.

Effects of heat treatment on microstructure and mechanical properties of squeeze casting AlSi9Mg alloy flywheel housings formed with local supplementary pressure

Targeted squeeze casting components of the thick-walled locations with local supplementary pressure (LSP) can effectively realize the local forced shrinkage, which is very significant for the elimination of shrinkage defects. In this paper, the effects of solid solution temperature, solid solution time, aging temperature and aging time on AlSi9Mg aluminum alloy flywheel housing with large wall thickness difference and complex structure formed with LSP were investigated. The results showed that the LSP effectively refined the microstructure and accelerated the spheroidization process of eutectic silicon, which reduced the heat treatment holding time significantly. The twinning growth of silicon particles effectively hindered the dislocation motion, relieved the stress concentration, and improved the strength. The fishbone-like AlSiMnFe phase were passivated after heat treatment. Heat treatment can enhance the plasticity by breaking and spheroidizing the coarse needle-like eutectic silicon, and enhance the strength by refining and homogenizing the β" phase precipitated in the alloy. The optimum heat treatment parameters are solid solution at 540 °C for 210 min and aging at 175 °C for 480 min. Under the optimum heat treatment condition, the ultimate tensile strength, yield strength and elongation for the position with LSP reached 306.1 MPa, 237.5 MPa, 13.29 %.

Using digital pathology to analyze the murine cerebrovasculature

Research on the cerebrovasculature may provide insights into brain health and disease. Immunohistochemical staining is one way to visualize blood vessels, and digital pathology has the potential to revolutionize the measurement of blood vessel parameters. These tools provide opportunities for translational mouse model research. However, mouse brain tissue presents a formidable set of technical challenges, including potentially high background staining and cross-reactivity of endogenous IgG. Formalin-fixed paraffin-embedded (FFPE) and fixed frozen sections, both of which are widely used, may require different methods. In this study, we optimized blood vessel staining in mouse brain tissue, testing both FFPE and frozen fixed sections. A panel of immunohistochemical blood vessel markers were tested (including CD31, CD34, collagen IV, DP71, and VWF), to evaluate their suitability for digital pathological analysis. Collagen IV provided the best immunostaining results in both FFPE and frozen fixed murine brain sections, with highly-specific staining of large and small blood vessels and low background staining. Subsequent analysis of collagen IV-stained sections showed region and sex-specific differences in vessel density and vessel wall thickness. We conclude that digital pathology provides a useful tool for relatively unbiased analysis of the murine cerebrovasculature, provided proper protein markers are used.

Research on the integral forming process of thin walled and thick mouth seamless gas cylinders

There is a considerable difference in wall thickness between the mouth and the cavity of thin-walled and thick-mouthed seamless gas cylinders, and the existing manufacturing processes are unable to effectively meet product requirements. To overcome such issue, a step-by-step boring-necking-spinning solution for gas cylinders was proposed, in which sufficient wall thickness is reserved for the mouth area of the cylinder blank, followed by necking-spinning to realize the overall forming of thin-walled, thick-mouthed seamless gas cylinders. The stress–strain distribution and geometric dimensional changes of gas cylinders during the spinning process were investigated by means of finite element simulation, and the effects of different process parameters on the stress and wall thickness of the bottle mouth were analyzed. Further, multi-objective optimization of the response surface model was performed using the NSGA-II algorithm to derive a set of optimal process parameters. Finally, the correctness of the simulation and optimization results was verified experimentally, and the expected geometry and optimal strain state of the gas cylinder were obtained. The newly developed processing solution represents a groundbreaking advancement in the manufacturing of thin-walled and thick-mouthed gas cylinders.

Acoustic behaviour in bottlenose dolphins during two different target discrimination tasks

Echolocation is an active sensory system that gives an acoustic representation of the surroundings by the animal emitting clicks, detecting and analysing echoes. However, little is known about dolphin biosonar in moving animals, as well as of the process of controlling click emissions, and the cues used by the animal to discriminate between different targets. We studied how bottlenose dolphins may use their dynamic sound production and hearing abilities, along with head and body movements, to detect and classify objects through echolocation. We designed two different experiments with blindfolded bottlenose dolphins (Tursiups truncatus) swimming freely along the pool and actively discriminating between two targets of three different materials, and a second one to determine the capability to discriminate wall thickness differences in cylindrical targets of the same material. By means of synchronized cameras and hydrophones, we observed clear differences between individuals of the same species in terms of ability to discriminate, but similar performance with the harbor porpoises in relation to the materials chosen with the difficulty of the task. Studying how the dolphins solved a simplified echolocation task, allow a better understanding of the processes behind target detection and discrimination capabilities during natural biosonar circumstances .

Stomatal opening efficiency is controlled by cell wall organization in Arabidopsis thaliana.

Stomatal function in plants is regulated by the nanoscale architecture of the cell wall and turgor pressure, which together control stomatal pore size to facilitate gas exchange and photosynthesis. The mechanical properties of the cell wall and cell geometry are critical determinants of stomatal dynamics. However, the specific biomechanical functions of wall constituents, for example, cellulose and pectins, and their impact on the work required to open or close the stomatal pore are unclear. Here, we use nanoindentation in normal and lateral directions, computational modeling, and microscopic imaging of cells from the model plant Arabidopsis thaliana to investigate the precise influences of wall architecture and turgor pressure on stomatal biomechanics. This approach allows us to quantify and compare the unique anisotropic properties of guard cells with normal composition, lower cellulose content, or alterations in pectin molecular weight. Using these data to calculate the work required to open the stomata reveals that the wild type, with a circumferential-to-longitudinal modulus ratio of 3:1, is the most energy-efficient of those studied. In addition, the tested genotypes displayed similar changes in their pore size despite large differences in wall thickness and biomechanical properties. These findings imply that homeostasis in stomatal function is maintained in the face of varying wall compositions and biomechanics by tuning wall thickness.

Associations between electrocardiographic findings and echocardiographic profiles in patients with hypertrophic cardiomyopathy

BackgroundThe relationships between electrocardiography (ECG) findings and echocardiographic profiles in patients with hypertrophic cardiomyopathy (HCM) are not fully understood. MethodsOne hundred forty patients (mean age: 62.9 ± 15.3 years, 96 men) with HCM were studied. We assessed the associations between ECG findings and echocardiographic findings including maximum left ventricular wall thickness, HCM subtypes and distribution of left ventricular hypertrophy (LVH): the LV was divided into basal, mid, and apical segments by dividing it into thirds along the long axis. ResultsIn ECG, LVH by voltage criteria, abnormal Q wave, negative T wave, and giant negative T wave (GNT) were observed in 74 (53 %), 30 (21 %), 132 (94 %), and 25 (18 %) of the patients, respectively. In two groups with and without an LVH pattern according to voltage criteria in ECG, there were no significant differences in maximum LV wall thickness, subtype of HCM, and distribution of LVH. Regarding an abnormal Q wave, the proportion of patients with LVH in the basal segment was significantly higher in patients with an abnormal Q wave than in patients without an abnormal Q wave (87 % vs 61 %, p = 0.008). An abnormal Q wave was not observed in patients with LVH confined to the apex. Patients with a GNT included patients with LVH located at only the apex (apical HCM), LVH from the mid segment to apex, and LVH from the base to apex. No GNT was found in patients with hypertrophy located in the upper region from the base to mid segment of the LV. ConclusionsIn patients with HCM, there was no significant correlation between the presence of LVH by voltage criteria in ECG and echocardiographic findings. An abnormal Q wave was associated with disproportionate hypertrophy of the basal wall and a GNT reflected the presence of LVH in the apical segment.

Investigation on the wall thickness variation of an eccentric tube in the rotary draw bending process

PurposeWhen bending a large diameter thin-walled tube, the thickn ess of outer side wall will reduce greatly, which leads to a decrease of structural strength of the tube. To solve this problem, this paper investigated the deformation principles of an eccentric tube in the rotary draw bending process, trying to find a way to reduce the wall thickness difference between inner and outer diameters.Design/methodology/approachAn finite element model is established for analyzing the deformation of an eccentric tube in rotary draw bending process. The wall thickness distribution of the formed pipe was analyzed along the axis and diameter, respectively.FindingsIt is found that there exists an optimal eccentricity between the inner and outer circle center of the tube cross-section. If the eccentricity of the tube is chosen properly, it is possible to get a bent tube with equal thickness of inner and outer side walls. In addition, it is also found the optimal eccentricity on the cross-section can be influenced by bending radius, wall thickness, diameter and bending angle. The optimal eccentricity increases greatly with the decreasing of bending radius, the increase of outer diameter and the increase of wall thickness. The influence of bending angle on the optimal eccentricity can be divided into two situations. When the bending angle is small, the optimal eccentricity increases with the increase of bending angle. When the bending angle exceeds a certain value, the pipe enters a stable forming state. The optimal eccentricity of the stable forming region does not change with the bending angle.Originality/valueSuch a research is beneficial for reducing the thickness difference between inner and outer side walls in the rotary draw bending process.

TRPC6 deficiency impairs middle cerebral artery myogenic response and brain spatial memory

Transient receptor potential channel 6 (TRPC6) is a nonselective cation channel belonging to the TRP ion channel family and expressed in vascular smooth muscle cells. TRPC6 regulates calcium influx in response to vascular wall mechanical stretch. A previous study reported that TRPC6 is critical for the myogenic response of the middle cerebral artery (MCA). Impaired MCA myogenic response is implicated in cerebral blood flow dysfunction and may promote cognitive deficits. In this study, we investigated whether TRPC6 contributes to the MCA myogenic response at pressure range (from 40 to 180 mmHg) in 12-week-old male wild-type (WT) and whole-body TRPC6 knock-out (TRPC6 KO) mice (n=5-8). Cognitive function (spatial learning and reference memory) was examined at 22 weeks of age using the Morris water maze test. Myogenic response in MCA was similar in WT and TRPC6 KO mice when perfusion pressure was increased from 40 to 80 mmHg. At higher pressures (>120 mmHg), however, TRPC6 KO mice displayed significantly reduced myogenic response compared to WT mice (3 % less of myogenic tone in TRPC6 KO compared to WT) which was further exacerbated when perfusion pressure was increased to 180 mmHg (9 % less of myogenic tone in TRPC6 KO compared to WT). There were no significant differences in wall thickness, wall-to-lumen ratio, vascular distensibility, incremental distensibility, or elastic modulus curves in MCA between WT and TRPC6 KO mice. Compared to WT mice, TRPC6 KO mice displayed similar spatial learning curves after 4 days of training but showed significantly impaired reference memory (14±1 % vs 29±4 % in the target quadrant) and reduced frequency (1.0±0.3 vs 2.1±0.4 in the target area crossing) compared to WT. These findings suggest that TRPC6 deficiency impairs myogenic response at higher perfusion pressures and spatial memory, even at a young age. (AG050049 (F.F), AG057842 (F.F), AG079336 (F.F), NIDDK R00DK113280, R01DK121411, NIGMS P20GM104357 and NIGMS U54GM115428) This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Age-related changes to cerebral artery stiffness and structure in mice

Introduction: With advancing age, there are changes in the structural and material properties of the arterial wall. While the age-related increase in stiffness is well described for large arteries, less is known about the structural changes to cerebral arteries with age. In response to increased blood pressure, as occurs with aging, arteries typically undergo remodeling that includes smooth muscle cell proliferation and collagen accumulation. This remodeling contributes to increased stiffness and reduces pulse pressure dampening, potentially leading to damage to arterioles and capillaries. We hypothesized that old cerebral arteries would display greater stiffness, wall thickness, collagen content, and smooth muscle content compared with young cerebral arteries. Methods: We studied old male (n=10, 24-27 months) and young male (n=9, 4-7 months) C57BL/6 mice. For measures of stiffness, isolated posterior cerebral arteries were exposed to pulsatile pressure (37.5 to 87.5 mmHg, 400 pulses/min) for 30 minutes. Artery diameters during the pulsation were recorded and used to calculate distension, β-stiffness index, and Peterson modulus of elasticity (EP). In sections of the middle cerebral arteries, total wall thickness and total collagen were measured in Masson’s trichrome-stained arteries. Collagen-1 and α-smooth muscle actin content were measured by immunofluorescence in middle cerebral artery sections. Data were analyzed by a Shapiro-Wilks test for normality, and young and old groups were compared by student’s t-test. Group comparisons for β-stiffness, EP, and percent change in diameter were made using a Mann-Whitney test. A p<0.05 was considered statistically significant. Data are mean±SD. Results: Cerebral arteries from young mice, compared with old mice, had a higher distensibility during the application of pulsatile pressure, measured by the percent change in diameter (8.0±4.0% vs. 5.1±2.5%, p=0.03) or absolute change in diameter (12.0±5.4 μm vs. 7.8±3.8 μm, p=0.03). Cerebral artery stiffness, calculated by β-stiffness index (13.1±6.5 AU vs. 21.9±13.8 AU, p=0.03) and EP (777±384 kPa 102 vs.1293±816 kPa 102, p=0.03) was lower in young mice compared with old mice. There was no difference in cerebral artery wall thickness between groups (6.9±3.0 μm vs. 9.6±2.3 μm, p=0.08). Cerebral arteries from old mice had greater amounts of α-smooth muscle actin compared to young mice (1.4±0.2 AU vs. 1.0±0.2 AU, p=0.009). Interestingly, cerebral arteries from old mice had lower collagen-1 compared to young mice (0.8±0.1 vs. 1.0±0.1 AU, p=0.01), but the opposite trend was observed for total collagen (26.3±13.6 AU vs. 17.6±9.6, p=0.06). Conclusion: These results demonstrate that advancing age results in increased functional stiffness of cerebral arteries. An age-related increase in smooth muscle is a potential cause of higher cerebral artery stiffness. This project was funded by NIH R01 AG064016 and the Oregon Medical Research Foundation. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Numerical simulation of squeeze casting of aluminum alloy flywheel housing with large wall thickness difference and complex shape

The squeeze casting process of ZL104 aluminum alloy flywheel housing with large wall thickness difference and complex shape was simulated by ProCAST software. The results show that the filling process was stable and could be divided into four stages: connection of channels, filling of horizontal zone, vertical direction, and difficult-filling zone. There were six characteristic zones with solidification lag, where shrinkage cavity and shrinkage porosity were obvious. The location prediction of defects was accurate. Through range analysis of defects volume, the optimal combination of process parameters was determined as pouring temperature of 650 °C, specific pressure of 48 MPa, mold temperature of 220 °C, local specific pressure of 800 MPa, and pressure delay time of 10 s (Side A) and 12 s (Side B). The maximum stress occurred in the thin-walled structure with fast solidification and large curvature. The simulation results were verified by the actual process.

Feed Curves for Controlling Ring Rolling Stability in Large-Scale Flat Ring Rolling Process.

Due to the large wall thickness difference and serious instability in the large-scale ring rolling process, most studies on the feed curve are not suitable for a large-scale ring. The production cost of the large-scale ring is high, and if plastic instability occurs, it will cause a great waste of resources. Therefore, in this study, a staged feed strategy based on the evolution of ring instability is proposed with the objective of controlling the rolling stability of a large-scale ring. Firstly, based on the law of rolling instability evolution, the rolling stage during the rolling process is divided. Secondly, the coordination of all rolling stages is proposed as a factor to design the feed curve. The feed scheme is determined using the central composite design (CCD) method, and then the established mathematical model is applied to obtain the radial feed curves of a large-scale flat ring with a 5 m diameter for different schemes. Next, the designed feed curve was submitted to finite element method (FEM) simulation. According to the FE simulation results, a rolling map for controlling roundness error, eccentricity and vibration is established. Finally, the feed curve in the stable region is input to the FE simulation and the production trial to obtain the results of roundness error, eccentricity and vibration. A comparison of the simulation and production trial results shows that they are in good agreement, which proves the reliability of the feed curve designed based on the stable rolling region in the roll map. Moreover, the machining amount for both the simulation and production trial is below the maximum machined value.

Conventional and genetic associations between resting heart rate, cardiac morphology and function as assessed by magnetic resonance imaging: Insights from the UK biobank population study.

To examine the direction, strength and causality of the associations of resting heart rate (RHR) with cardiac morphology and function in 20,062 UK Biobank participants. Participants underwent cardiac magnetic resonance (CMR) and we extracted CMR biventricular structural and functional metrics using automated pipelines. Multivariate linear regression adjusted for the main cardiovascular risk factors and Two-sample Mendelian Randomization analyses were performed to assess the potential relationship, grouped by heart rate and stratified by sex. Each 10 beats per minute increase in RHR was linked with smaller ventricular structure (lower biventricular end-diastolic volume and end-systolic volume), poorer left ventricular (LV) function (lower LV ejection fraction, global longitude strain and global function index) and unhealthy pattern of LV remodeling (higher values of myocardial contraction fraction), but there is no statistical difference in LV wall thickness. These trends are more pronounced among males and consistent with the causal effect direction of genetic variants interpretation. These observations reflect that RHR has an independent and broad impact on LV remodeling, however, genetically-predicted RHR is not statistically related to heart failure. We demonstrate higher RHR cause smaller ventricular chamber volume, poorer systolic function and unhealthy cardiac remodeling pattern. Our findings provide effective evidence for the potential mechanism of cardiac remodeling and help to explore the potential scope or benefit of intervention.

Effect of T6 heat treatment on microstructure and mechanical properties of large-weight aluminum alloy flywheel housing parts formed by local-loading squeeze casting

In this research, ZL104 aluminum alloy flywheel housing with large wall-thickness difference and complex shape were formed via local-loading squeeze casting. The effects of T6 heat treatment process parameters (solution time and temperature, aging time and temperature) on mechanical properties and microstructure of ZL104 aluminum flywheel housing were studied. The microstructure of the formed parts with heat treatment was analyzed by scanning electron microscope (SEM), electron backscattered diffraction (EBSD) and optical microscope (OM). The mechanical property test results indicated that the improvement of strength was limited with the increase of solution temperature and solution time, but the elongation improved significantly. For solution treatment, the optimum mechanical properties (ultimate tensile strength, yield strength, and elongation were 243 MPa, 133 MPa, and 14%) were obtained at 550 °C/3 h. The strength increased first and then decreased with the increase of aging time. After 8 h/175 °C aging treatment (following by solid solution), the maximum tensile strength and yield strength reached 312 MPa and 251 MPa, respectively. After T6 heat treatment, the morphology of Si spheroidized and coarsened obviously. The Si particles with fine size were formed. Continuous dynamic recrystallization occurred during heat treatment but was not very sufficient.