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Cryogenic machining uses liquid nitrogen (LN2) as a coolant. This machining process can reduce the cutting temperature and increase tool life. Titanium alloys have been widely used in the aerospace and automobile industries because of their high strength-to-weight ratio. However, they are difficult to machine because of their poor thermal properties, which reduce tool life. In this study, we applied cryogenic machining to titanium alloys. Orthogonal cutting experiments were performed at a low cutting speed (1.2 - 2.1 m/min) in three cooling conditions: dry, cryogenic, and cryogenic plus heat. Cutting force and friction coefficients were observed to evaluate the machining characteristics for each cooling condition. For the cryogenic condition, cutting force and friction coefficients increased, but decreased for the cryogenic plus heat condition

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The surface roughness and cutting forces are the important factors for the machine-part quality during the hard-turning process. The aim of this paper is to optimize hard-cutting conditions via implementation of response surface methodology (RSM). The experiments were conducted for the hard-turning process with the Box-Behnken design. The validation of the surface roughness and cutting forces was performed with the obtained 2nd order polynomial regression model. The results showed that the surface roughness was strongly dependent upon the RPM. The diminution of the cutting force was attributed to the low feed rate and the depth of cut. On the basis of the RSM, optimized cutting conditions of RPM, feed rate, and depth of cut are 3440, 0.0352 [mm/rev], and 0.03 [mm]. In this optimal cutting condition, the surface roughness can be around Ra= 0.202 ??m

Simultaneous Aortic and Tricuspid Valve Endocarditis due to Complication of Sinus of Valsalva Rupture

We experienced a case of ruptured aneurysm of the sinus of Valsalva, and this resulted in simultaneous aortic and tricuspid valve endocarditis through a shunt. The echocardiography showed a ruptured sinus of Valsalva aneurysm to the right atrium with a shunt. The aortic non-coronary cusp was fibro-thickened with vegetation. Vegetations of the septal leaflet and the anterior leaflet of the tricuspid valve were also found. The blood culture grew Enterococcus garllinarum. We replaced both tricuspid and aortic valve with successful surgical result

Experimental Study on Coordinated Heading Control of Four Vessels Moored Side by Side

A floating type liquefied natural gas (LNG) bunkering terminal has been under development in Korea since 2014; the terminal is designed to receive LNG from an LNG carrier (LNGC) and transfer it to two other LNG bunkering shuttles (LNGBS) simultaneously. The operational feasibility of the LNG loading and unloading processes has been confirmed. When four vessels are moored side by side with mooring ropes and fenders, their positions must be maintained within the designed allowable criteria. In addition, the floating bunkering terminal (FLBT) has its own mooring system, an internal turret with catenary mooring lines and stern tunnel thrusters to maintain its own position and control the vessel heading. In this study, we investigated the operational feasibility of the FLBT during the LNG loading and unloading operations with four vessel mooring configurations and heading controls. A series of model tests was done in the ocean engineering basin of the Korea Research Institute of Ships and Ocean engineering. The motion responses of the four vessels were determined using an optical measurement system, and the tensile loads on ship-to-ship mooring ropes and the compressive loads on ship-to-ship fenders were measured using one-axis load cells. A white noise test was done and the results were compared with the numerical results for the purpose of validation. Then, four combined environmental conditions were presented both without heading control and with several heading control cases. Finally, we determined the available safe bunkering heading ranges taking into account the tensile loads on the mooring ropes

TSLP Induces Mast Cell Development and Aggravates Allergic Reactions through the Activation of MDM2 and STAT6

Thymic stromal lymphopoietin (TSLP) is known to promote T helper type 2 cell–associated inflammation. Mast cells are major effector cells in allergic inflammatory responses. We noted that the population and maturation of mast cells were reduced in TSLP-deficient mice (TSLP-/-). Thus, we hypothesized that TSLP might affect mast cell development. We found that TSLP induced the proliferation and differentiation of mast cells from bone marrow progenitors. TSLP-induced mast cell proliferation was abolished by depletion of mouse double minute 2 (MDM2) and signal transducers and activators of transcription 6 (STAT6), as an upstream activator of MDM2. TSLP-/-, in particular, had a considerable deficit in the expression of MDM2 and STAT6. Also, the TSLP deficiency attenuated mast cell–mediated allergic reactions through the downregulation of STAT6 and MDM2. In an antibody microarray chip analysis, MDM2 expression was increased in atopic dermatitis patients. These observations indicate that TSLP is a factor for mast cell development, and that it aggravates mast cell–mediated immune responses

The effect of Cs/FA ratio on the long-term stability of mixed cation perovskite solar cells

Formamidinium lead iodide (FAPbI3) is ideal for highly efficient and operationally stable perovskite solar cells (PSC). However, a primary challenge for FAPbI3 PSC is to suppress the phase transition from the photoactive black phase into the yellow nonperovskite δ-phase. The preparation of Cs-containing mixed FAPbI3 perovskite by cation stoichiometric engineering is demonstrated and the influence of the Cs/FA ratio on its phase stability and device performance is discussed. By exploring the optimal ratio of Cs and FA cations in Cs x FA1−x Pb(I0.94Br0.06)3 perovskite, an inverted planar device with Cs0.17FA0.83Pb(I0.94Br0.06)3 composition shows the best power conversion efficiency (PCE) of 16.5% in an active area of 1.08 cm2. More importantly, the Cs0.17FA0.83Pb(I0.94Br0.06)3 perovskite photoactive layer showed remarkable long-term stability, maintaining 88.1% of its initial efficiency for 1128 h in the presence of moisture and oxygen and without any encapsulation. The excellent long-term stability is found to originate from the appropriate tolerance factor and low thermodynamic decomposition energy, which underpins the strong potential for the commercialization of Cs-containing mixed FAPbI3 PSCs

Pilot KaVA monitoring on the M87 jet: confirming the inner jet structure and superluminal motions at sub-pc scales

We report the initial results of our high-cadence monitoring program on the radio jet in the active galaxy M87, obtained by the KVN and VERA Array (KaVA) at 22 GHz. This is a pilot study that preceded a larger KaVA-M87 monitoring program, which is currently ongoing. The pilot monitoring was mostly performed every two to three weeks from December 2013 to June 2014, at a recording rate of 1 Gbps, obtaining the data for a total of 10 epochs. We successfully obtained a sequence of good quality radio maps that revealed the rich structure of this jet from <~1 mas to 20 mas, corresponding to physical scales (projected) of ~0.1-2 pc (or ~140-2800 Schwarzschild radii). We detected superluminal motions at these scales, together with a trend of gradual acceleration. The first evidence for such fast motions and acceleration near the jet base were obtained from recent VLBA studies at 43 GHz, and the fact that very similar kinematics are seen at a different frequency and time with a different instrument suggests these properties are fundamental characteristics of this jet. This pilot program demonstrates that KaVA is a powerful VLBI array for studying the detailed structural evolution of the M87 jet and also other relativistic jets.Comment: 10 pages, 9 figures, accepted for publication in PAS