Analysis of the effect of initial conditions on the initial development of a turbulent jet

The effect of the initial condition at the jet exit on the downstream evolution, particularly within the potential core length, were numerically investigated as well as with available experimental data. In order to select the most dependable computational model for the present numerical experiment, a comparative study has been performed with different turbulence models at k-epsilon level, and it was found that the k-epsilon-gammma model yields superior prediction accuracy over other conventional models. The calculated results show that the potential core length and the spreading rate the initial mixing layer are dependent on the initial length scale as well as the turbulent kinetic energy at the jet exit. Such effect of the initial length scale increases with higher initial turbulence level. An empirical parameter has been devised to collapse the calculated data of the potential core length and the spreading rate with various initial conditions onto a single curve

Comparison of 4-French versus 5-French sheaths for diagnostic coronary angiography via the snuffbox approach

Background: Although a shorter hemostasis duration would be expected when compared with the conventional radial approach as the diameter of the distal radial artery is smaller than that of the conventional radial artery, the optimal duration of hemostasis in diagnostic coronary angiography (CAG) via the distal radial approach, termed the snuffbox approach, has not been well investigated.Methods: Data from 171 patients were retrospectively collected (55 and 116 patients in the 4-French [Fr] and 5-Fr sheath groups, respectively). The patients had suspected myocardial ischemia and were undergoing diagnostic CAG via the snuffbox approach at a single center between January 2019 and August 2019.Results: The mean age of the study population was 67.6 ± 11.0 years, and 69% were male. The left snuffbox approach was performed in 146 (85.4%) patients. The mean snuffbox puncture time, defined as the time interval between local anesthesia and sheath cannulation, was 145.1 ± 120.8 s. The hemostasis duration was significantly shorter in the 4-Fr sheath group than in the 5-Fr sheath group (70 [62–90] vs. 120 [120–130] min; p < 0.001). There were local hematomas, defined as ≤ 5 cm in diameter, at the puncture site in 8 (4.7%) patients. Moreover, there were no conventional and distal radial artery occlusions, assessed by manual pulse, after hemostasis in the study population during hospitalization.Conclusions: Successful hemostasis was obtained within 2 h for diagnostic CAG via the snuffbox approach using the 4-Fr or 5-Fr sheaths

Ultralow noise optical pulse generation in an actively mode-locked quantum-dot semiconductor laser

We report excellent noise performance of an external-cavity actively mode-locked laser based on quantum-dot gain medium. Optical pulse trains with less than 7.5 fs residual timing jitter (1 Hz to 10 MHz) for a 12.8 GHz harmonically mode-locked ring laser were obtained. This result represents, to our knowledge, the lowest residual jitter reported from actively mode-locked semiconductor lasers, and shows that quantum-dot mode-locked lasers are promising as sources of ultralow noise optical pulse trains

Investigation of Enhanced Polygon Wall Boundary Model in PNU-MPS Method

With regard to demonstration of fluid flow, there are two descriptions which are Eulerian description and Lagrangian description. In the field of CFD (Computational Fluid Dynamics), a number of studies relevant to grid method based on Eulerian description have been conducted generally. However, when the grid method is employed to simulate flow field, it is inevitable to give consideration to convection term which generates severe numerical diffusion and fluctuation. To obtain the accuracy of solution, a different type of method based on Lagrangian description is come to the fore. Numerical approaches following Lagrangian description have been called meshfree or particle method. Even though particle method does not accompany convection term and fully satisfies conservation of mass, its studies have not been carried out extensively because it is difficult to implement the boundary conditions correctly due to insufficient number of particles in the vicinity of boundary. It affects directly the stability of flow field and accuracy in computation. In MPS (Moving Particle Semi-implicit) method [1], fixed-type of dummy particles are placed inside wall boundary. By placing extra particles as the wall, it seems to be not easy to satisfy the boundary condition for sharp-edged or extremely thin body configuration. In this study, the enhanced polygon wall boundary model, which was suggested originally by Mitsume et al. [2], is employed to the PNU-MPS (Pusan-National-University-modified MPS) method [3] to improve and stabilize the analysis of fluid flow with arbitrary-shaped body including sharp-edged body configuration without any additional particles. The developed simulation method, called as PNU-MPS-POLY, is adopted to the Couette flow and the lid-driven cavity flow with various corner angles. The present simulation results are validated through comparison with the analytic solutions, the experiments [4], and other simulation results [5,6]

Optimization of extraction process for enhancement of antioxidant activity of Acer mono bark

Response surface methodology (RSM) was used for finding the optimum extraction condition of Acer mono bark. Twenty experimental conditions were set based on three key variables such as temperature, time and pressure by signalling reaction variables with 5 levels of - 2, - 1, 0, 1, 2 in accordance with central composite design for proceeding extraction and antioxidant tests. The optimized condition for the highest extraction yields was 13.10% at 83.48°C, 54.36 MPa for 13.08 minutes. For DPPH radical scavenging ability, an optimal condition was 92.89% at 88.50°C, 49.69 MPa for 15.08 minutes, and for SOD-like activity 40.69% at 85.21°C, 53.28 MPa for 15.83 minutes. The optimized condition for total polyphenol content was 4.23 mg/g at 81.51°C, 52.92 MPa for 14.79 minutes. The most optimized extraction condition was determined to be at 85°C, 52 MPa for 14 minutes for considering both extraction yield and its biological activities of this plant

Ring finger protein 126 (RNF126) suppresses ionizing radiation-induced p53-binding protein 1 (53BP1) focus formation

Cells have evolved sophisticated mechanisms to maintain genomic integrity in response to DNA damage. Ionizing radiation (IR)-induced DNA damage results in the formation of IR-induced foci (iRIF) in the nucleus. The iRIF formation is part of the DNA damage response (DDR), which is an essential signaling cascade that must be strictly regulated because either the loss of or an augmented DDR leads to loss of genome integrity. Accordingly, negative regulation of the DDR is as critical as its activation. In this study, we have identified ring finger protein 126 (RNF126) as a negative regulator of the DDR from a screen of iRIF containing 53BP1. RNF126 overexpression abolishes not only the formation of 53BP1 iRIF but also of RNF168, FK2, RAP80, and BRCA1. However, the iRIF formation of H2AX, MDC1, and RNF8 is maintained, indicating that RNF126 acts between RNF8 and RNF168 during the DDR. In addition, RNF126 overexpression consistently results in the loss of RNF168-mediated H2A monoubiquitination at lysine 13/15 and inhibition of the non-homologous end joining capability. Taken together, our findings reveal that RNF126 is a novel factor involved in the negative regulation of DDR, which is important for sustaining genomic integrity