Long-axis Direction Research Articles

Application of Computer-Aided Design Software to the Simulation and Analysis of Composite Material Properties in Housing Engineering Structures

Reinforced polymer composites are widely used in engineering applications due to their excellent mechanical properties, and this paper combines experiments and numerical simulations to fully examine the properties of the composites. The article takes the reinforced concrete structure of civil engineering as the basis for experimental testing on the basic properties of carbon fiber composites in its application. Subsequently, the intrinsic model of reinforced concrete and carbon fiber composites was constructed, and each finite element unit of the member was selected to simulate and finite element analysis the performance of the composites through ABAQUS computer-aided design software. The results show that increasing the diameter of carbon fibers will reduce the number of carbon fibers at the same time, which will reduce the toughness of the composite material, random and chaotic distribution of carbon fibers for the improvement of the compressive properties of concrete can achieve a relatively balanced effect, and the high elastic modulus carbon fibers for the improvement of uniaxial and cyclic compressive properties of concrete play a dominant role. In addition, the oriented elliptical fibers in the long-axis direction have a significant increase in the modulus of elasticity and strength of the material, and this phenomenon will become more and more obvious with the increase of the length-to-diameter ratio. The reasonable structural design may help to improve the performance of composites and enhance their adaptability for engineering applications.

Drag force on a microrobot propelled through blood

Controlling microrobot locomotion in vessels and capillaries is crucial for precise drug delivery and minimally invasive surgeries. However, this is challenging due to the complex interactions with red blood cells (RBCs) and the difficulty navigating within the dense environment. Here, we construct a numerical framework to evaluate the relative resistance coefficient (Cr*\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${C}_{{{{{{{{\\rm{r}}}}}}}}}^{* }$$\\end{document}) of a microrobot propelled through RBC suspensions. Our experiments validate the numerical results. We find that Cr*\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${C}_{{{{{{{{\\rm{r}}}}}}}}}^{* }$$\\end{document} increases for smaller microrobots and higher hematocrit levels, while magnetic force strength weakly impacts Cr*\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${C}_{{{{{{{{\\rm{r}}}}}}}}}^{* }$$\\end{document}. Cr*\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${C}_{{{{{{{{\\rm{r}}}}}}}}}^{* }$$\\end{document} is smaller than the resistance coefficient of a macroscale robot estimated from the apparent viscosity of the RBC suspension. The aspect ratio of a prolate ellipsoidal microrobot influences Cr*\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${C}_{{{{{{{{\\rm{r}}}}}}}}}^{* }$$\\end{document} along its long-axis direction. Additionally, machine learning accurately predicts Cr*\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${C}_{{{{{{{{\\rm{r}}}}}}}}}^{* }$$\\end{document}. These insights could enhance the design and control of microrobots for medical applications.

Simplification of selective imaging of dislocation loops: diffraction-selected on-zone STEM

ABSTRACT Contrary to the conventional belief that, in transmission electron microscopy (TEM), selective and sharp imaging of dislocation loops can be realized only by accurate tilting of a specimen from the condition that the symmetrical axis of incident electron beam distribution is parallel to a zone axis of the TEM specimen (on-zone condition), we demonstrate that selective dark-field (DF) imaging of dislocation loops at on-zone condition is possible with a scanning TEM (STEM) mode that uses an objective lens aperture to select a diffraction disk of interest. Diffraction-selected on-zone STEM (DsoZ-STEM) has been applied to selective DF imaging of dislocation loops with a short axis length of <2 nm in a single-crystal aluminum irradiated by argon ions and an electron beam at room temperature. It was found that a Kikuchi line enhances the contrast among the dislocation loops and the matrix of DsoZ-STEM images. DsoZ-STEM obeyed g·b invisibility criterion and showed good agreement with a typical visibility change of a dislocation line and a loop in conventional DF images with a specific pair of ± g. In addition, dislocation loops always showed much higher brightness in the inner side compared to the outer side in DsoZ-STEM images, simplifying the distinction of dislocation loops with apparently the same long-axis direction but different b. Thus, DsoZ-STEM can simplify the selective DF imaging for the determination of the number and the character of dislocation loops.

Non-covalent Supramolecular 1D Alternating Copolymer in Crystal toward 2D Anisotropic Photon Transport.

To realize organic integrated optoelectronic circuits, there is a need for anisotropic optical waveguides at the micro/nanoscale. Anisotropic alignment of one-dimensional (1D)-ordered supramolecular structures composed of light-emissive π-conjugated molecules in a crystal may meet the requirements of such waveguides. Here, we designed a bipyridyl-appended acrylonitrile-based π-conjugated molecule 1, which produced a 1D supramolecular polymer constructed through non-covalent bonding between a lone pair in 1 and a σ-hole in 1,4-diiodo-2,3,5,6-tetrafluorobenzene 2. The 1D copolymer of 1 and 2 is aligned horizontally with the two-dimensional (2D) crystal surface because of the angle-controlled supramolecular synthons. As a result of control over the non-covalent bonding direction, anisotropic photoluminescence and photon transport (optical waveguiding) characteristics are realized by orienting the transition dipole moment horizontally with respect to the 2D surface. Compared with the loss coefficient αL =52dBcm-1 for the long-axis direction of the 2D platelet cocrystal, a very large difference of αS =2111dBcm-1 is present in the crystal short-axis direction. The anisotropic waveguiding ability, αL/αS, is estimated to be 41, which is more than an order of magnitude greater than previously reported 2D platelet crystal waveguides. This supramolecular synthon provides an approach to designing anisotropic photon transporters and highly regulated optical logic circuits.

Cardiomyocyte orientation recovery at micrometer scale reveals long-axis fiber continuum in heartwalls.

Coordinated cardiomyocyte contraction drives the mammalian heart to beat and circulate blood. No consensus model of cardiomyocyte geometrical arrangement exists, due to the limited spatial resolution of whole heart imaging methods and the piecemeal nature of studies based on histological sections. By combining microscopy and computer vision, we produced the first-ever three-dimensional cardiomyocyte orientation reconstruction across mouse ventricular walls at the micrometer scale, representing a gain of three orders of magnitude in spatial resolution. We recovered a cardiomyocyte arrangement aligned to the long-axis direction of the outer ventricular walls. This cellular network lies in a thin shell and forms a continuum with longitudinally arranged cardiomyocytes in the inner walls, with a complex geometry at the apex. Our reconstruction methods can be applied at fine spatial scales to further understanding of heart wall electrical function and mechanics, and set the stage for the study of micron-scale fiber remodeling in heart disease.

Development, sand control mechanism and hydrocarbon accumulation of beach-bar sandstone in a saline lake basin: A case from the Neogene of southwestern Qaidam Basin, NW China

Based on the data of field outcrops, drilling cores, casting thin sections, well logging interpretation, oil/gas shows during drilling, and oil/gas testing results, and combined with modern salt-lake sediments in the Qinghai Lake, the Neogene saline lake beach-bars in southwestern Qaidam Basin are studied from the perspective of sedimentary characteristics, development patterns, sand control factors, and hydrocarbon accumulation characteristics. Beach-bar sand bodies are widely developed in the Neogene saline lake basin, and they are lithologically fine sandstone and siltstone, with wavy bedding, low-angle cross bedding, and lenticular-vein bedding. In view of spatial-temporal distribution, the beach-bar sand bodies are stacked in multiple stages vertically, migratory laterally, and extensive and continuous in NW−SE trending pattern in the plane. The stacking area of the Neogene beach-bar sandstone is predicted to be 3 000 km2. The water salinity affects the sedimentation rate and offshore distance of beach-bar sandstone, and the debris input from the source area affects the scale and enrichment of beach-bar sandstone. The ancient landform controls the morphology and stacking style of beach-bar sandstone, and the northwest monsoon driving effect controls the long-axis extension direction of beach-bar sandstone. The beach-bars have a reservoir-forming feature of “one reservoir in one sand body”, with thick beach-bar sand bodies controlling the effective reservoir distribution and oil-source faults controlling the oil/gas migration and accumulation direction. Three favorable exploration target zones in Zhahaquan, Yingdong−eastern Wunan and Huatugou areas are proposed based on the analysis of reservoir-forming elements.

Polymerized Thermally Activated Delayed-Fluorescence Small Molecules: Long-Axis Polymerization Leads to a Nearly Concentration-Independent Luminescence.

Nowadays numerous thermally activated delayed fluorescence (TADF) polymers have been developed for PLEDs to realize high device performance and tunable emission colors. However, they often possess a strong concentration dependence on their luminescence including aggregation-caused quenching (ACQ) and aggregation-induced emission (AIE). Herein, we first report a nearly concentration-independent TADF polymer based on the strategy of polymerized TADF small molecules. It is found that when a donor-acceptor-donor (D-A-D) type TADF small molecule is polymerized through its long-axis direction, the triplet state is distributed along the polymeric backbone to effectively suppress the unwanted concentration quenching. Unlike the short-axis one with an ACQ effect, the photoluminescent quantum yield (PLQY) of the resultant long-axis polymer remains almost unchanged with the increasing doping concentration. Accordingly, a promising external quantum efficiency (EQE) up to 20 % is successfully achieved in a whole doping control window of 5-100 wt. %.

Dependence of apparent diffusion coefficient on slice position in magnetic resonance diffusion imaging

PurposeThe position dependence of the apparent diffusion coefficient (ADC) in magnetic resonance imaging (MRI) by echo-planar imaging (EPI)- and turbo spin echo (TSE)-diffusion-weighted imaging (DWI) was assessed using phantoms. MethodsSix pure water-filled containers were placed parallel to the direction of the static magnetic field from the center of the magnetic field to the foot direction (five containers) and the head direction (one container). Six slice positions were set, and a cross-section image was scanned at the center of each container using a 1.5-T MRI scanner. Diffusion times for both EPI- and TSE-DWI were matched as much as possible. The slice thickness was adjusted to match the signal-to-noise ratio (SNR) at the center of the magnetic field for both sequences. A B1 map was analyzed. The ADC and SNR at each position of both sequences were tested using the Wilcoxon signed-rank test (P = 0.05) and compared using Friedman and Steel–Dwass multiple comparison tests (P = 0.05). Pearson correlation coefficients between ADC and SNR and between ADC and flip angle (FA) were calculated. ResultsADC decreased significantly with distance from the center of the magnetic field for both EPI-DWI and TSE-DWI (P < 0.05). TSE-ADC was significantly higher than EPI-ADC for all combinations (P < 0.01). Based on the Friedman test, the SNR of EPI- and TSE-DWI was significantly different and depended on the slice position (P < 0.01). The Pearson correlation coefficient between ADC and SNR was 0.78 in EPI-DWI and 0.60 in TSE-DWI, whereas that between ADC and FA was 0.97 in EPI-DWI and 0.94 in TSE-DWI. The FA decreased by 0.048 and 0.047° per mm from the center of the magnetic field to head and foot directions, respectively. ConclusionADC depends on the slice position and decreases with an increase in distance from the magnetic field center. Caution should be taken when comparing and quantitatively evaluating the ADC at sites shifted in the long-axis direction.

Experimental investigation of a novel sleeved member with additional friction dampers

A novel sleeved member with additional friction dampers, which is abbreviated as the frictional sleeved member (FSM) in this paper, was proposed to ensure the stability and greater energy dissipation of compression members in space structures. The FSM consisted of an inner core, an outer sleeve, and additional friction dampers. Two semicircular pipes were fastened by high-strength bolts to obtain the outer sleeve. Friction dampers using composite friction materials were distributed on both sides of the sleeve in the long-axis direction. Cyclic compression-unloading tests of four compression members were completed in this paper. The test results showed that the FSM exhibited the following characteristics compared with an ordinary assembled sleeve member (ASM): comparable lateral-constraint capacity, greater resistance, and greater energy dissipation capacity under tiny axial displacement (0–4 mm). Nonmetallic friction pads had a stable energy dissipation capacity and slight start-sliding displacement, which met the energy dissipation requirements of the FSM under tiny displacements. The additional friction dampers of the FSM had a slight effect on the deformation mode of the inner core, but the resistance and secant stiffness of the specimen were both significantly improved. The outer sleeve of the FSM adopted an asymmetric friction connection, leading to a periodic local increase and an overall decrease in the clamping force of the high-strength bolts. The extrusion between the outer sleeve and the buckling inner core had a negligible effect on the clamping force of the high-strength bolts.

Stability Analysis on the Moon’s Rotation in a Perturbed Binary Asteroid

Numerical calculation provides essential tools for deep space exploration, which are indispensable to mission design and planetary research. In a specific case of binary asteroid defense such as the DART mission, an accurate understanding of the possible dynamical responses and the system’s stability and engineers’ prerequisite. In this paper, we discuss the numeric techniques for tracking the year-long motion of the secondary after being perturbed, based upon which its rotational stability is analyzed. For long-term simulations, we compared the performances of several integrating schemes in the scenario of a post-impact full two-body system, including low- and high-order Runge–Kutta methods, and a symplectic integrator that combines the finite element method with a symplectic integral format. For rotational stability analysis of the secondary, we focus on the rotation of the secondary around its long-axis. We calculated a linearised error propagation matrix and found that, in the case of tidal locking of the secondary to the primary, the rotation is stable; as the perturbation amplitude of the spin angular velocity of the secondary increases, the rotation will lose stability and will be prone to being unstable in the long-axis direction of the secondary. Furthermore, we investigated the one-year-long influences of the non-spherical perturbations of the primary and the secondary.

Growth kinetics of ceramic grains during liquid phase sintering in Mo2FeB2-based cermets

Mo2FeB2-based cermets with different hard phases were fabricated by reaction boronizing sintering. SEM, EDS, and TEM were utilized to evaluate the growth kinetics of Mo2FeB2 hard-phase grains with different morphologies during liquid phase sintering. During the sintering stages of L1 and L2, the growth of elongated grains along the long-axis conformed to the cubic law. Combined with the observed rough interface between the hard and binder phases, the growth mechanism along the long-axis could be identified as diffusion-controlled since atoms did not have to overcome large energy barriers to nucleate. Meanwhile, the grain growth along the short-axis was primarily accomplished via 2-D nucleation on the smooth interface, which was mainly controlled by interface reaction during the liquid phase sintering since the driving force in the short-axis direction failed to meet the requirements of critical driving force (∆Gc). In addition, the principal control mechanism of nearly equiaxed grains growing in L1 and L2 was identical to the long-axis direction of elongated grains. Nevertheless, the third phase (Fe23B6) at the interface of nearly equiaxed grains affected grain growth, resulting in variations in grain size and growth activation energy during the L1 and L2 sintering stages.

Facilitated harvesting of a radial artery superficial palmar branch flap for reconstruction of moderate finger skin defects

Radial artery superficial palmar branch harvesting is technically challenging, especially for inexperienced hand surgeons. The short pedicle and a damaged recipient digital artery require proximal digital artery dissection and relatively long pedicles. Herein, we describe a facilitated flap elevation technique and its application in various cases. From 2013 to 2021, 10 patients with finger injuries received radial artery superficial palmar flaps. We assessed flap survival, sizes, complications, two-point discrimination, and the Semmes-Weinstein monofilament test results. The main shortcoming of a radial artery superficial palmar flap is its short pedicle. Therefore, we developed a long skin flap design in the long axis direction, and the accompanying vein was dissected proximally to the radial artery to obtain a long pedicle. All flaps survived. The median flap dimension was 5.0×2.2cm (maximum size: 6.0×2.0+5.0×2.0cm [for a bilobed flap]). While nerve reconstruction was performed in one patient, all patients had preserved sensation. A sufficiently long pedicle can be obtained by dissecting the accompanying vein proximally to the radial artery. Perforators found in the skin around the scaphoid tubercle in all cases suggest value in including this region in flap design. To obtain a longer pedicle, the flap was developed with the long-skin design in the long-axis direction. Although the accompanying vein is usually thin and difficult to anastomose with the finger vein, its proximal dissection led to the accompanying vein of the radial artery that facilitated the harvesting of a sufficiently long vein.

Two Stage Intravital Imaging Mouse Model to Assess Venous Thromboembolism in Sickle Cell Disease

Sickle cell disease (SCD) patients have an increased risk of venous thromboembolism (VTE). Population-based studies demonstrated that VTE has a cumulative incidence rate of approximately 25% in adult SCD patients and is associated with higher risk of mortality. VTE in SCD is most commonly manifested as deep vein thrombosis (DVT) with associated pulmonary embolism (PE). Although autopsy studies have regularly discovered pulmonary thromboembolic lesions in SCD patients, the pathophysiology of VTE in SCD remains largely unknown mostly due to the lack of relevant animal VTE model. Understanding the mechanisms that promote VTE in SCD is imperative to identify its prevention and treatment measures.To elucidate the cellular, molecular and biophysical mechanisms of VTE in SCD we developed an innovative two stage intravital imaging analysis experimental model in SCD mice. DVT in SCD mice was induced by surgical ligation of femoral vein. Venous thrombus formation was visualized using intravital multi-photon-excitation (MPE) microscopy. Venous thrombus took the form of a large mass of elliptical shape which extended in the long-axis direction of the femoral vein. It was composed of fibrin, erythrocytes and sparse platelets. Over time, thrombus was infiltrated by migrating neutrophils. To trigger acute PE, femoral vein ligation was removed and the venous thrombus was observed to spontaneously detach and travel to the SCD mouse lung. This method allowed real time visualization of acute PE in vivo using MPE microscopy of intact lung in live breathing mice. Acute PE involved embolization of the pulmonary arterioles and the arteriolar bottle-necks located at the junction of pulmonary arterioles and capillaries. The embolization of arteriolar circulation led to loss of blood flow in the arterioles and the down-stream capillaries.Herein we introduce an intravital microscopy approach to probe VTE in SCD live mouse. Our model has potential application in investigating the molecular determinants of VTE associated with SCD as well as evaluating efficacy of new antithrombotic drugs. DisclosuresSundd: Bayer: Research Funding; CSL Behring Inc: Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding.

Perineal stapled prolapse resection in combination with Thiersch operation for relapsed rectal prolapse: a case report

BackgroundTreatment options for complete rectal prolapse include over 100 procedures. In previous reports, operative rectal prolapse repair, regardless of the technique by perineal approach, was associated with high recurrence rates. However, there is no consensus on the optimal surgical procedure for relapsed rectal prolapse.Case presentationA 97-year-old woman was admitted to our hospital with a chief complaint of complete rectal prolapse measuring > 5 cm. The patient had a history of laparoscopic anterior suture rectopexy without sigmoid resection under general anesthesia for complete rectal prolapse one year prior. The patient’s postoperative course was uneventful. However, her dementia worsened (Hasegawa’s dementia scale: 5/30 points) after the first operation. Further, moderate-to-severe aortic valve stenosis was first diagnosed with heart failure 6 months after the operation. Nine months after the initial surgery, she experienced a recurrence of complete rectal prolapse measuring approximately 5 cm. Considering the coexistence of advanced age, severe dementia, and aortic valve stenosis, surgery under general anesthesia was not indicated. Perineal stapled prolapse resection in combination with the t operation was planned because of its minimal invasiveness and shortened hospital stay. The procedure was performed by a team of two surgeons in the jack knife position, under spinal anesthesia.The prolapse was cut along the long-axis direction with three linear staplers and resected along the short-axis direction with four linear staplers. The cross-section of the linear stapler was reinforced with 3-0 Vicryl sutures. After rectal resection, the Thiersch operation using 1-0 nylon thread 1 cm away from the anal verge was additionally performed. The operative time was 24 min, and intraoperative blood loss was 1 mL. The postoperative course was uneventful. Three months after the operation, no recurrence was observed, and defecation function was good with improvements of Wexner score.ConclusionsPerineal stapled prolapse resection in combination with the Thiersch operation could be a useful option for patients with relapsed rectal prolapse and with poor general condition, who are not indicated for other surgical procedures.

Spatiotemporal Dynamic Analysis of A-Level Scenic Spots in Guizhou Province, China

A-level scenic spots are a unique evaluation form of tourist attractions in China, which have an important impact on regional tourism development. Guizhou is a key tourist province in China. In recent years, the number of A-level scenic spots in Guizhou Province has been increasing, and the regional tourist economy has improved rapidly. The spatial distribution evolution characteristics and influencing factors of A-level scenic spots in Guizhou Province from 2005 to 2019 were measured using spatial data analysis methods, trend analysis methods, and geographical detector methods. The results elaborated that the number of A-level scenic spots in all counties of Guizhou Province increased, while in the south it developed slowly. From 2005 to 2019, the spatial distribution in A-level scenic spots were characterized by spatial agglomeration. The spatial distribution equilibrium degree of scenic spots in nine cities in Guizhou Province was gradually developed to reach the “relatively average” level. By 2019, the kernel density distribution of A-level scenic spots had formed the “two-axis, multi-core” layout. One axis was located in the north central part of Guizhou Province, and the other axis ran across the central part. The multi-core areas were mainly located in Nanming District, Yunyan District, Honghuagang District, and Xixiu District. From 2005 to 2007, the standard deviation ellipses of the scenic spots distribution changed greatly in direction and size. After 2007, the long-axis direction of the ellipses gradually formed a southwest to northeast direction. We chose elevation, population density, river density, road network density, tourism income, and GDP as factors, to discuss the spatiotemporal evolution of the scenic spots’ distribution with coupling and attribution analysis. It was found that the river, population distribution, road network density, and the A-level scenic spots’ distribution had a relatively high coupling phenomenon. Highway network density and tourist income have a higher influence on A-level tourist resorts distribution. Finally, on account of the spatiotemporal pattern characteristics of A-level scenic spots in Guizhou Province and the detection results of influencing factors, we put forward suggestions to strengthen the development of scenic spots in southern Guizhou Province and upgrade the development model of “point-axis network surface” to the current “two-axis multi-core” pattern of tourism development. This study can explain the current situation of the spatial development of tourist attractions in Guizhou Province, formulate a regulation mechanism of tourism development, and provide a reference for decision-making to boost the high-quality development of the tourist industry.

Left ventricular remodelling in mitral valve prolapse patients: implications of apical papillary muscle insertion.

Mitral valve prolapse (MVP) causes left ventricular (LV) remodelling even in the absence of significant mitral regurgitation. To evaluate whether apical insertion of the papillary muscle (PM) influences the pattern and severity of MVP-related LV remodelling. All MVP patients who underwent CMR at our institution between December 2008 and December 2019 were included, thoroughly reviewed and grouped according to apical/non-apical PM insertion. Apical PM insertion was found in 53/92 patients (58%) and associated with mitral leaflet thickening (P < 0.01) and a trend towards higher prevalence of mitral annular disjunction (P = 0.05). Whereas no differences in ventricular volumes or ejection fraction were found, patients with apical PM insertion showed more lateral wall remodelling with mid lateral wall thinning [2.1 (1.8-2.5) vs. 4.0 (3.5-5.0) mm, P < 0.01], increased LV eccentricity and a lower GCS at this level (15 ± 3% vs. 20 ± 3%, P < 0.01). In long-axis direction, increased end-diastolic mid lateral wall angulation was found (i.e. angle <155° measured in the thinnest point of the mid lateral wall in four-chamber view) with a higher angle variation during systole (25 ± 11° vs. 17 ± 8°, P < 0.01). Remarkably, PM fibrosis was significantly more frequent in patients with apical PM insertion (i.e. 66% vs. 28%, P < 0.01). Finally, a higher burden of premature ventricular complexes (>5%) and non-sustained ventricular tachyarrhythmias was found in patients with apical PM insertion: 53% vs. 25% (P = 0.04) and 38% vs. 18% (P = 0.04), respectively. Apical PM insertion is part of the phenotypic spectrum of MVP, impacts significantly LV remodelling, and potentially may be related to increased ventricular arrhythmogenicity.

Left ventricular remodeling in mitral valve prolapse patients: implications of apical papillary muscle implantation

Abstract Funding Acknowledgements Type of funding sources: None. BACKGROUND Mitral valve prolapse (MVP) causes left ventricle (LV) remodeling even in the absence of significant mitral regurgitation. PURPOSE We sought to evaluate whether apical implantation of the papillary muscle (PM) has an influence on the pattern and severity of MVP-related LV remodeling. METHODS All MVP patients who underwent Cardiovascular Magnetic Resonance at our institution between December 2008 and December 2019 were included, thoroughly reviewed and grouped according to apical/non-apical PM implantation. RESULTS Apical PM implantation was found in 53/92 patients (58%) and associated with mitral leaflet thickening (p &amp;lt; 0.01) and a trend toward higher prevalence of mitral annular disjunction (p = 0.05). Whereas there were no differences between groups concerning ventricular volumes and ejection fraction, mitral valve prolapse location or severity of mitral valve insufficiency, patients with apical PM implantation showed more lateral wall remodeling with mid lateral wall thinning (2.1 [1.8-2.5]mm vs. 4.0 [3.5-5.0]mm, p &amp;lt; 0.01), increased LV eccentricity and a lower Global Circumferential Strain at this level (15 ± 3% vs. 20 ± 3%, p &amp;lt; 0.01). In long-axis direction, increased end-diastolic mid lateral wall angulation was found (i.e., angle &amp;lt;155° measured in the thinnest point of the mid lateral wall in 4-chamber view) with a higher angle variation during systole (25 ± 11° vs. 17 ± 8° p &amp;lt; 0.01). Remarkably, PM fibrosis was significantly more frequent in patients with apical PM implantation (i.e., 66% vs. 28%, p &amp;lt; 0.01). Importantly, PM fibrosis was observed in the apically implanted PM in the vast majority of cases (86%), showing a strong association between PM fibrosis and its apical implantation. Finally, a higher burden of premature ventricular complexes (&amp;gt;5%) and non-sustained ventricular tachyarrhythmias was found in patients with apical PM implantation: 53% vs. 25% (p = 0.04) and 38% vs. 18% (p = 0.04), respectively. CONCLUSIONS Apical PM implantation is part of the phenotypic spectrum of MVP, significantly impacts LV remodeling and potentially may be related to increased ventricular arrhythmogenicity.

Effect of precipitates on the cryogenic fracture toughness of 9%Ni steel flux cored arc weld

The microstructure and fracture toughness of 9%Ni steel flux cored arc welds with different heat input were investigated. CTOD results showed that the fracture toughness of the weld decreased with the increasing amount of precipitates at room temperature and at cryogenic temperature. Micro-regional force and deformation (MRFD) of the weld was investigated by finite element analysis. Precipitates have a significant impact on MRFD. In the stretching process, high stress concentration and local plastic deformation occurred around precipitates, which decreased crack propagation resistance in interdendritic region. The increment of precipitate amount enhanced the stress concentration and local plastic deformation. The effect of rod-shaped Laves phase on MRFD is much higher than globular-shaped carbide. For Laves phase, the maximum local plastic strain and peak stress has close relationship with its aspect ratio and its angle between long-axis direction and load-direction. The size of carbide has little influence on MRFD. Due to the high local plastic deformation and peak stress, microcracks formed at interdendritic region near precipitates during stretching at cryogenic temperature.

Bioactive hierarchical silk fibers created by bioinspired self-assembly

Artificial recapitulation of the hierarchy of natural protein fibers is crucial to providing strategies for developing advanced fibrous materials. However, it is challenging due to the complexity of the natural environment. Inspired by the liquid crystalline spinning of spiders, we report the development of natural silk-like hierarchical fibers, with bundles of nanofibrils aligned in their long-axis direction, by self-assembly of crystallized silk fibroin (SF) droplets. The formation of self-assembled SF fibers is a process of coalesced droplets sprouting to form a branched fibrous network, which is similar to the development of capillaries in our body. The as-assembled hierarchical SF fibers are highly bioactive and can significantly enhance the spreading and growth of human umbilical vein endothelial cells compared to the natural SF fibers. This work could help to understand the natural silk spinning process of spiders and provides a strategy for design and development of advanced fibrous biomaterials for various applications.

Predicting Near-Field Strong Ground Motion of the Huaxian Ms8.5 Earthquake Based on Uncertainty Factors of Asperities

The Weihe Plain is at high risk of disastrous earthquakes, such as the Huaxian Ms8.5 earthquake, which caused enormous casualties and economic losses. Therefore, reproducing the strong ground motion characteristics of the Huaxian earthquake is important for seismic design and disaster mitigation. The empirical Green’s function method is used to predict the ground motion characteristics of the Huaxian Ms8.5 earthquake by considering the uncertainty factors of asperities, considering the limited observations in the Weihe Plain and the inaccessibility of the Earth’s interior. The uncertainty asperity factors can be studied by the logic tree method, and source models considering these factors are constructed here. The uncertainty factors include the seismic moment M0, number of subfaults N, stress drop of an asperity Δσ, and asperity area Sa. The asperity area is assigned values of 19%, 22%, and 25% of the fault rupture area; the M0 values of the corresponding asperities account for 40%, 44%, and 48% of the entire M0; and there are two to four asperities. The permutations are combined into multiple-asperity source models. The two-asperity source models reflect the Huaxian earthquake characteristics better than the three- or four-asperity models. The asperity area accounts for approximately 22–25% of the fault rupture area, while the M0 of the corresponding asperities accounts for 44% and 48% of the entire M0. The long-axis direction of the ground motion distribution is the same as that of the mountains southeast of the Weihe Plain. The azimuth angle of the elliptical long axis is approximately 40–60° northeast. The greater the magnitude is, the more complex the number, location, and area of the asperities. This research extends the application of the empirical Green’s function method and can numerically simulate seismic intensity characteristics in areas with destructive earthquakes but few seismic records.