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ACS Omega Apr 2024This study explored the impact of varying weight percentages of TiMoVWCr high-entropy alloy (HEA) powder addition on A356 composites produced using friction stir...
This study explored the impact of varying weight percentages of TiMoVWCr high-entropy alloy (HEA) powder addition on A356 composites produced using friction stir processing (FSP). Unlike previous research that often focused on singular aspects, such as mechanical properties, or microstructural analysis, this investigation systematically examined the multifaceted performance of A356 composites by comprehensively assessing the microstructure, interfacial bonding strength, mechanical properties, and wear behavior. The study identified a uniform distribution of TiMoVWCr HEA powder in the composition A356/2%Ti2%Mo2%V2%W2%Cr, highlighting the effectiveness of the FSP technique in achieving homogeneous dispersion. Strong bonding between the reinforcement and matrix material was observed in the same composition, indicating favorable interfacial characteristics. Mechanical properties, including tensile strength and hardness, were evaluated for various compositions, demonstrating significant improvements across the board. The addition of 2%Ti2%Mo2%V2%W2%Cr powder enhanced the tensile strength by 36.39%, while hardness improved by 62.71%. Similarly, wear resistance showed notable enhancements ranging from 35.56 to 48.89% for different compositions. Microstructural analysis revealed approximately 1640.59 grains per square inch for the A356/2%Ti2%Mo2%V2%W2%Cr processed composite at 500 magnifications. In reinforcing Al composites with Ti, Mo, V, W, and Cr high-entropy alloy (HEA) particles, each element imparted distinct benefits. Titanium (Ti) enhanced strength and wear resistance, molybdenum (Mo) contributed to improved hardness, vanadium (V) promoted hardenability, tungsten (W) enhanced wear resistance, and chromium (Cr) provided wear resistance and hardness. Anticipating the potential applications of the developed composite, the study suggests its suitability for the aerospace sector, particularly in casting lightweight yet high-strength parts such as aircraft components, engine components, and structural components, underlining the significance of the investigated TiMoVWCr HEA powder-modified A356 composites.
PubMed: 38708242
DOI: 10.1021/acsomega.3c07837 -
Frontiers in Cardiovascular Medicine 2024Closure of paravalvular leak (PVL) regurgitation after self-expandable (SE) transcatheter aortic valve implantation (TAVI) may be more challenging than after...
Intravascular lithotripsy (IVL) enabled the percutaneous closure of a severely calcified paravalvular leak regurgitation following implantation of a self-expandable transcatheter aortic valve: a case report.
BACKGROUND
Closure of paravalvular leak (PVL) regurgitation after self-expandable (SE) transcatheter aortic valve implantation (TAVI) may be more challenging than after balloon-expandable (BE) valve implantation.
CASE SUMMARY
An 85-year-old woman suffering from long-standing atrial fibrillation and severe symptomatic aortic stenosis underwent SE TAVI (26 mm Evolut™ R®, Medtronic Inc., MN, USA). A total of eighteen months after TAVI she was admitted for congestive heart failure and two-dimensional (2D) transesophageal echocardiography (TEE) color Doppler showed moderate-severe PVL regurgitation due to a long and heavily calcified leak located below the left coronary sinus. The patient was deemed to be at prohibitive surgical risk and a catheter-based PVL closure procedure was planned. A first attempt to cross the PVL from the femoral artery was unsuccessful due to an inappropriate angle between the catheter and the entry site of this hard-to-approach calcified leak. A Terumo hydrophilic guidewire 0.35 inch-260 cm from the right radial artery was then successfully advanced across the leak to the left ventricle (LV); however, of most of the catheters used, only a Glidecath 4-Fr could cross the leak over the hydrophilic wire. The hydrophilic guidewire was replaced with a stiffer guidewire that, after creating a loop in the LV, was advanced across the self-expandable valve into the descending aorta where it was snared and externalized through the left femoral artery, thus creating an arterio-arterial (AA) loop. A 6-Fr Multipurpose guiding catheter was advanced over the exchange wire and the leak was crossed with an additional 0.0014 coronary guidewire (PILOT, Abbott Vascular), predilated with two non-compliant balloon dilatation catheters, and finally, the PVL was engaged with a 3.0 mm × 12 mm Shockwave balloon (Shockwave Medical Inc, Santa Clara, California, USA). Intravascular lithotripsy (IVL) application to this highly calcified leak and the increased support provided by the stiff guidewire finally allowed the progression of the 6-Fr dedicated delivery sheath (ODS III) into the LV. A 5 mm square twist (ST) device (PLD, Occlutech, Helsingborg, Sweden) was successfully deployed within the leak and the final echocardiographic and angiographic control confirmed the effective PVL closure.
DISCUSSION
In patients at high surgical risk with moderate to severe regurgitation after SE TAVI due to a hard-to-approach calcified long tract, an extra AA support loop is mandatory during percutaneous PVL closure. Furthermore, IVL application greatly facilitates the progression of the delivery sheath and occluder which is key to a successful procedure.
PubMed: 38450376
DOI: 10.3389/fcvm.2024.1359711 -
Science Advances Jan 2024Organic light-emitting diodes (OLEDs) that efficiently emit near-infrared (NIR) light and consume little power will create valuable applications for OLEDs beyond just...
Organic light-emitting diodes (OLEDs) that efficiently emit near-infrared (NIR) light and consume little power will create valuable applications for OLEDs beyond just displays. Here, we report such a NIR-OLED with high operational stability that can be used as a light source for three-dimensional sensing of object's surfaces. Using a narrow-energy-gap material as a host for producing NIR hyperfluorescence system, we fabricated a NIR-OLED exhibiting intense emission at 930 nm with a high external electroluminescence quantum efficiency of more than 1% at a current density of 100 milliamperes per square meter without any degradation even after more than 300 hours of operation. The NIR-OLEDs were integrated with dense complementary metal-oxide semiconductor circuits to make a micro-NIR-OLED projector (0.21 inch, 230,400 pixels). By actively driving the projector on a pixel by pixel and projecting their emission onto objects, we successfully scanned and sensed the surfaces in three dimensions with invisible NIR.
PubMed: 38181084
DOI: 10.1126/sciadv.adj6583 -
Data in Brief Oct 2023Floods are common natural disasters worldwide and pose substantial risks to life, property, food production, and natural resources. Effective measures for flood...
Floods are common natural disasters worldwide and pose substantial risks to life, property, food production, and natural resources. Effective measures for flood mitigation and warning are essential. Southeast Texas is still at significant risk of flooding, and Lamar University is assisting the region with asset management of a flood sensor network for flooding events. This network provides real-time water stage information. Lamar University developed a survey program to measure elevation and coordinates at each sensor site location to make this data more useful for flood monitoring and mapping. This paper overviews the measurement of the elevation and coordinates of 74 networked flood sensors and various flood stage thresholds at critical points that flood decision-makers can use for reference at each site. In the first phase of this program, these sensors were deployed throughout a 7-county region spanning nearly 6,000 square miles in Southeast Texas. The latitude and longitude of the sensors and their elevations were determined using survey-grade Global Navigation Satellite System (GNSS) technology. Various Continually Operating Reference Stations (CORS) were utilized for post-processing to achieve sub-inch resolution. The flood stage thresholds, water level sensors elevation, and the elevations and positions of other critical surrounding points are viewable to the public through two online repositories and a web-based sensor management dashboard. The data is used to aid with decisions related to road closures or modeling efforts by mitigation decision-makers, emergency managers, and the public, including the Texas Department of Transportation, Houston Transtar, the National Weather Service, and the Sabine River Authority of Texas (SRA).
PubMed: 37680348
DOI: 10.1016/j.dib.2023.109504 -
Micromachines May 2023This paper presents the fabrication and characterization of a biaxial MEMS (MicroElectroMechanical System) scanner based on PZT (Lead Zirconate Titanate) which...
This paper presents the fabrication and characterization of a biaxial MEMS (MicroElectroMechanical System) scanner based on PZT (Lead Zirconate Titanate) which incorporates a low-absorption dielectric multilayer coating, i.e., a Bragg reflector. These 2 mm square MEMS mirrors, developed on 8-inch silicon wafers using VLSI (Very Large Scale Integration) technology are intended for long-range (>100 m) LIDAR (LIght Detection And Ranging) applications using a 2 W (average power) pulsed laser at 1550 nm. For this laser power, the use of a standard metal reflector leads to damaging overheating. To solve this problem, we have developed and optimised a physical sputtering (PVD) Bragg reflector deposition process compatible with our sol-gel piezoelectric motor. Experimental absorption measurements, performed at 1550 nm and show up to 24 times lower incident power absorption than the best metallic reflective coating (Au). Furthermore, we validated that the characteristics of the PZT, as well as the performance of the Bragg mirrors in terms of optical scanning angles, were identical to those of the Au reflector. These results open up the possibility of increasing the laser power beyond 2W for LIDAR applications or other applications requiring high optical power. Finally, a packaged 2D scanner was integrated into a LIDAR system and three-dimensional point cloud images were obtained, demonstrating the scanning stability and operability of these 2D MEMS mirrors.
PubMed: 37241642
DOI: 10.3390/mi14051019 -
Scientific Reports May 2023A clinical efficacy study of 0.025-inch guidewires (GWs) according to mechanical property analysis has not been reported yet. This study was designed to evaluate the... (Randomized Controlled Trial)
Randomized Controlled Trial
A clinical efficacy study of 0.025-inch guidewires (GWs) according to mechanical property analysis has not been reported yet. This study was designed to evaluate the clinical efficacy of a newly developed 0.025-inch GW for biliary access according to the basic mechanical property. Commercially available 0.025-inch GWs were in vitro tested based on parameters of mechanical property. Patients with naïve papilla requiring diagnostic or therapeutic ERCP were randomly assigned to an experimental 0.025-inch newly developed GW or a control 0.025-inch GW group. Technical success rate of wire-guided cannulation (WGC), difficult biliary cannulation (DBC), and adverse event rates were measured in this multicenter randomized trial. The technical success rate of primary WGC was 79.1% (151 of 191) in the experimental group and 70.8% (131 of 185) in the control group (95% two-sided confidence interval: 8.25%; p < 0.001; for a noninferiority margin of 15%). The technical success rate including cross-over to each other was also non-inferior. However, the chi-square test showed a statistical difference (81.7% vs. 68.1%; p = 0.002). Median biliary cannulation time was shorter in the experimental group (53 s vs. 77 s; p = 0.047). The rate of DBC was more frequent in the control group (34.6% vs. 50.3% p = 0.002). Multivariate analysis revealed that control group was one of contributing factors for DBC. Overall rate of post-ERCP pancreatitis was not different (4.7% vs. 8.6%; p = 0.125). WGC using a newly developed GW with superior physical performance GW in a bench test showed similar clinical efficacy and the rate of DBC was significantly lower in experimental GW.
Topics: Humans; Cholangiopancreatography, Endoscopic Retrograde; Catheterization; Biliary Tract; Pancreatitis; Treatment Outcome
PubMed: 37169945
DOI: 10.1038/s41598-023-34846-w -
Journal of Functional Morphology and... Feb 2023Firefighters often complete air management courses (AMC) to assess the ability to tolerate personal protective equipment, appropriately manage the breathing system and...
UNLABELLED
Firefighters often complete air management courses (AMC) to assess the ability to tolerate personal protective equipment, appropriately manage the breathing system and assess occupational performance. Little information is known relative to the physiological demands of AMCs, nor how to assess work efficiency in order to characterize occupational performance and evaluate progress.
PURPOSE
To assess the physiological demands of an AMC and examine differences across BMI categories. A secondary aim was to develop an equation to assess work efficiency in firefighters.
METHODS
Fifty-seven firefighters (Women, n = 4; age: 37.2 ± 8.4 yr.; height: 182.0 ± 6.9 cm; body mass: 90.8 ± 13.1 kg; BMI: 27.8 ± 3.6 kg·m) completed an AMC per routine evaluation while wearing a department issued self-contained breathing apparatus and full protective gear. Course completion time, starting pounds per square inch (PSI) on the air cylinder, changes in PSI, and distance traveled were recorded. All firefighters were equipped with a wearable sensor integrated with a triaxial accelerometer and telemetry to assess movement kinematics, heart rate, energy expenditure, and training impulse. The AMC consisted of an initial section involving a hose line advance, rescue (body drag), stair climb, ladder raise, and forcible entry. This section was followed by a repeating loop, which consisted of a stair climb, search, hoist, and recovery walk. Firefighters repeated the course loop until the self-contained breathing apparatus air supply pressure reached 200 PSI, at which time they were instructed to lay down until the PSI reached zero.
RESULTS
Average completion time was 22.8 ± 1.4 min, with a mean distance of 1.4 ± 0.3 km and an average velocity of 2.4 ± 1.2 m·s. Throughout the AMC, the mean heart rate was 158.7 ± 11.5 bpm equating to 86.8 ± 6.3% of the age-predicted max heart rate and a training impulse of 55 ± 3 AU. Mean energy expenditure was 464 ± 86 kcals and work efficiency was 49.8 ± 14.9 km·PSI·s. Regression analysis determined that fat-free mass index (R = 0.315; β = -5.069), body fat percentage (R = 0.139; β = -0.853), fat-free mass (R = 0.176; β = -0.744), weight (R = 0.329; β = -0.681), and age (R = 0.096; β = -0.571) were significant predictors of work efficiency.
CONCLUSIONS
The AMC is a highly aerobic task with near-maximal heart rates reached throughout the course. Smaller and leaner individuals achieved a higher degree of work efficiency during the AMC.
PubMed: 36810505
DOI: 10.3390/jfmk8010021