Enhanced Non-Contact Grip Force and Swirl Stability by a Combined Venturi-Vortex Air Head.

A combination of the venturi module and the vortex cup was proposed to solve vortex instability and to enhance grip capacity. Mounting a venturi suction pad inside the vortex cup improved vacuum generation efficiency. When the vortex cup properly maintained the non-contact air gap and generated an equivalent vacuum to achieve a sealing effect around the open gap of the suction pad, the combined head improved grip capacity and stabilized the non-contact environment. Furthermore, the flow patterns around the venturi chamber and the swirl inside the vortex cup were analyzed based on the design elements of each module. In a module that integrated some of the venturi's features internally, increased air consumption of the vortex cup was required than that of the venturi. However, it supported a wide range of non-contact grips. The coupled model effectively protected the vacuum suction features of the venturi suction pad in all non-contact environments in that range.

Antioxidant Properties of Hydrogen Gas Attenuates Oxidative Stress in Airway Epithelial Cells.

Oxidative stress plays a crucial role in the development of airway diseases. Recently, hydrogen (H2) gas has been explored for its antioxidant properties. This study investigated the role of H2 gas in oxidative stress-induced alveolar and bronchial airway injury, where A549 and NCI-H292 cells were stimulated with hydrogen peroxide (H2O2) and lipopolysaccharide (LPS) in vitro. Results show that time-dependent administration of 2% H2 gas recovered the cells from oxidative stress. Various indicators including reactive oxygen species (ROS), nitric oxide (NO), antioxidant enzymes (catalase, glutathione peroxidase), intracellular calcium, and mitogen-activated protein kinase (MAPK) signaling pathway were examined to analyze the redox profile. The viability of A549 and NCI-H292 cells and the activity of antioxidant enzymes were reduced following induction by H2O2 and LPS but were later recovered using H2 gas. Additionally, the levels of oxidative stress markers, including ROS and NO, were elevated upon induction but were attenuated after treatment with H2 gas. Furthermore, H2 gas suppressed oxidative stress-induced MAPK activation and maintained calcium homeostasis. This study suggests that H2 gas can rescue airway epithelial cells from H2O2 and LPS-induced oxidative stress and may be a potential intervention for airway diseases.

A flow visualization model of duodenogastric reflux after esophagectomy with gastric interposition.

BACKGROUND: Our goal was to verify surgical factors that affect duodenogastric reflux (DGR) after esophagectomy through the use of a flow visualization model that would mimic an intrathoracic gastric tube. METHODS: Transparent gastric tube models for different routes (retrosternal space [RS] and posterior mediastinum [PM]) were fabricated. Various distal pressures were applied to the experimental model filled with water, and the flow was recorded with a high-speed camera. The volume and maximum height of the refluxate through the pylori of two different sizes (7.5 mm, 15 mm) in two different postures (upright, semi-Fowler) was measured by analyzing the video clips. RESULTS: For the large pylorus setting, when the pressures of 20, 30, and 40 mmHg were applied in the upright position, the volumes of the refluxate in the RS/PM tubes were 87.7 ± 1.1/96.4 ± 1.7 mL, 150.8 ± 1.1/158.0 ± 3.2 mL, and 156.8 ± 3.3/198.0 ± 4.7 mL (p < 0.05), and the maximum heights were 101.6 ± 4.8/113.4 ± 2.9 mm, 151.4 ± 2.2/165.4 ± 1.5 mm, and 166.1 ± 1.7/193.7 ± 6.6 mm (p < 0.05). The data for the small pylorus setting or in the semi-Fowler position showed similar tendencies. For any given route, posture or pressure setting, DGR in the large pylorus model was definitively higher than that for small one. CONCLUSIONS: This fluid mechanics study demonstrates posterior mediastinal gastric interposition or pyloric drainage procedure, or both, is associated with high reflux of duodenal contents.

A flow visualization model of gastric emptying in the intrathoracic stomach after esophagectomy.

BACKGROUND: Our goal was to verify surgical factors that affect gastric emptying after esophagectomy through the use of a flow visualization model to mimic an intrathoracic gastric tube. METHODS: The route and length of the gastric tube model was determined from postoperative computed tomography (CT) images of 5 patients who underwent esophagectomy with gastric interposition. Transparent tubes of various sizes (20, 40 and 60 mm in diameter) were fabricated cylindrically for comparison. 200 mL of liquid with a different viscosity were poured through the gastric tube, and the flow was recorded with a high-speed camera. Transit time to pass the pylori of different sizes (7.5 and 15 mm in diameter) was measured by analyzing the video clips. RESULTS: For the small pylorus setting, emptying times in the 20-, 40-, and 60-mm tubes were 3.17 ± 0.07, 6.55 ± 0.28, and 7.60 ± 0.69 seconds for water (p < 0.000), and 15.56 ± 0.55, 19.75 ± 0.47, and 23.28 ± 0.32 seconds for glycerine (p < 0.000). For the large pylorus setting, emptying times were 2.66 ± 0.10, 2.93 ± 0.05, and 3.37 ± 0.10 seconds for water (p < 0.000) and 9.95 ± 0.18, 11.18 ± 0.33, and 10.95 ± 0.16 seconds for glycerin (p < 0.000). For any given tube size and liquid setting, emptying times for the small pylorus model were always significantly longer than those for the large one (p < 0.000). CONCLUSIONS: This fluid mechanics study demonstrates a narrow gastric tube or pyloric drainage procedure, or both, improves gastric emptying. This finding may help reduce the incidence of delayed gastric emptying after esophagectomy with gastric interposition.

Effects of arterial port design on blood flow distribution in hemodialyzers.

BACKGROUND/AIMS: Blood flow profiles in fiber bundles depend on the design of the arterial port and affects the biocompatibility of the hemodialyzer. We analyzed the effects of arterial port design on blood flow distribution in fiber bundles using nonintrusive imaging techniques. METHODS: The velocity fields in arterial ports and the hemodynamics in fiber bundles were analyzed for hemodialyzers with different configurations using particle image velocimetry and perfusion computed tomography. RESULTS: In a hemodialyzer with standard arterial ports, high blood flow profiles in the central and peripheral regions and low blood profiles in the middle region were developed due to jet flow and vortices around the jet. In a hemodialyzer with spiral arterial ports, higher flow profiles were developed due to the central vortices that decrease perfusion into the fiber bundles. CONCLUSION: The arterial port design of hemodialyzers should be optimized such that jet flow and vortices do not impair dialysis efficiency and biocompatibility.