Search

Near β Ti alloys typically show high specific strength and provide a wide spectrum of mechanical properties with different heat treatments. In this work, a commercial near β Ti alloy Ti-5553 (Ti-5Al-5V-5Mo-3Cr-0.5Fe) was prepared through powder metallurgy using the blended elemental powder approach. Additionally, alloy modifications with 6 wt.% Nb (Ti-6Nb-5Al-2.5V-5Mo-3Cr-0.5Fe) and 12 wt.% Nb (Ti-12Nb-5Al-5Mo-3Cr-0.5Fe) were investigated. Specimens were prepared by uniaxial cold compaction of blended powders at room temperature with sintering conducted at 1300°C for 2 h under Ar atmosphere. Microstructure investigation revealed reasonable homogenisation of alloying elements and colony sizes in the order of 80-100 μm with porosity below 10%. Moreover, the bending strength of as-sintered Ti-12Nb-5Al-5Mo-3Cr-0.5Fe was about 850 MPa and the micro-Vickers hardness was approximately 370 HV. The alloy modifications with Nb increased strength without loss in flexural strain. [ABSTRACT FROM AUTHOR]

Background: Hepatocellular carcinoma (HCC) is a common malignant disease of the liver in China and Japan. The purpose of this study was to compare the outcomes of HCC patients after hepatectomy between two regional medical centers in China and Japan. Methods: Data on HCC after hepatectomy were collected from January 2005 to December 2014 from Nagasaki University Hospital in Nagasaki, Japan and the Second Affiliated Hospital of Nanchang University in Nanchang, China. The patient and tumor characteristics, HCC etiology, and overall survival rates after hepatectomy were investigated. Results: Two hundred patients in the Nagasaki group and 238 patients in the Nanchang group were diagnosed with HCC and underwent hepatectomy. The major underlying liver diseases were hepatitis C infection (32%, 64/200) and nonalcoholic steatohepatitis (NASH) (34.5%, 69/200) in the Nagasaki group, while in the Nanchang group, hepatitis B infection (79.4%, 189/238) was the dominant etiology. Large tumors (> 5 cm), the presence of a tumor capsule and a high alpha-fetoprotein value (≥ 400 U/L) were more frequently observed in the Nanchang group as compared with the Nagasaki group (p

The cavitation cloud generated by submerged high-speed water jet has periodicity. The periodicity is provided by alternately repeating the bubbles generation and shedding process and cavitation nucleus filling process. Therefore, the construction of the filling process allows control of the shedding frequency of the cavitation clouds and may improve the aggressive intensity of the cavitating jet. In this paper, the water flow holes were provided at the nozzle throat outlet in order to form a stable and continuous filling flow. The aggressive intensity of this nozzle was compared by the mass loss of JIS A1050P. In addition, the cavitating jet was observed with a high speed video camera to confirm the characteristics of the jet. As a result, the mass loss per unit area increased as the diameter of the water flow holes increased. It is speculated that the enhanced flow around the cavitating jet due to the action of the water flow holes caused the increase in the damming pressure on the specimen. The increase in damming pressure increased the impact density and collapse impact force of the cavitation bubbles. Moreover, the large water flow holes resulted in stabilization of the shedding frequency of the cavitation clouds and growth scale. It may be a factor that the stable supply of cavitation nuclei to the cavitation main generation field was realized. However, since the water flow holes did not change the shedding frequency significantly, it is considered that the influence of the frequency on the aggressive intensity is small in this experiment.

During conventional submerged laser peening, the impact force induced by laser ablation is used to produce local plastic deformation pits to enhance metallic material properties, such as fatigue performance. However, a bubble, which behaves like a cavitation, is generated after laser ablation, known as “laser cavitation.” On the contrary, in conventional cavitation peening, cavitation is generated by injecting a high-speed water jet into the water, and the impacts of cavitation collapses are utilized for mechanical surface treatment. In the present paper, a mechanical surface treatment mechanism using laser cavitation impact, i.e., “laser cavitation peening”, was investigated, and an improvement in fatigue strength from laser cavitation peening was demonstrated. The impact forces induced by laser ablation and laser cavitation collapse were evaluated with a polyvinylidene fluoride (PVDF) sensor and a submerged shockwave sensor, and the diameter of the laser cavitation was measured by observing a high-speed video taken with a camera. It was revealed that the impact of laser cavitation collapse was larger than that of laser ablation, and the peening effect was closely related to the volume of laser cavitation. Laser cavitation peening improved the fatigue strength of stainless-steel welds.

Ferromagnetic (FM) interlayer exchange coupling of ion-beam sputtered Fe/Ge multilayers was investigated by off-specular polarized neutron scattering measurements. We observed a monotonously growing correlation of magnetic moments in the out-of-plane direction with decreasing Ge thickness. The magnetic properties of the multilayers with and without the FM interlayer exchange coupling agree well with the three- and two-dimensional random anisotropy model, respectively, assuming an FM interlayer exchange coupling comparable to the direct exchange interaction within the sample plane. The results of the Fe/Ge multilayers were used to invoke FM interlayer exchange coupling in a neutron polarizing supermirror in order to extend its bandwidth. Typically, the bandwidth is limited due to a Curie temperature close to room temperature of the thinnest Fe layers with less than 3 nm. We propose a modified layer sequence of the neutron polarizing supermirror, where the minimum Fe thickness was set to 3.5 nm, whereas the Ge thickness was reduced. A performance test of the neutron polarizing supermirror showed that the FM interlayer exchange coupling contributed to the presence of the magnetization comparable to the bulk and resulted in a marked extension in the bandwidth. [ABSTRACT FROM AUTHOR]

Friction stir welding (FSW) is an attractive solid-state joining technique for lightweight metals; however, fatigue properties of FSWed metals are lower than those of bulk metals. A novel mechanical surface treatment using cavitation impact, i.e., cavitation peening, can improve fatigue life and strength by introducing compressive residual stress into the FSWed part. To demonstrate the enhancement of fatigue properties of FSWed metal sheet by cavitation peening, aluminum alloy AA5754 sheet jointed by FSW was treated by cavitation peening using cavitating jet in air and water and tested by a plane bending fatigue test. The surface residual stress of the FSWed part was also evaluated by an X-ray diffraction method. It was concluded that the fatigue life and strength of FSWed specimen were improved by cavitation peening. Whereas the fatigue life at σa = 150 MPa of FSWed specimen was about 1/20 of the bulk sheet, cavitation peening was able to extend the fatigue life of the non-peened FSW specimen by 3.6 times by introducing compressive residual stress into the FSWed part. This is the first paper to demonstrate the improvement of fatigue properties of FSWed metallic sheet by cavitation peening.

Background: The current high‐level hepatectomy (HLH) is certified by the Japanese Society of Hepato‐Biliary‐Pancreatic Surgery (JSHBPS), comprising only anatomical hepatectomies above Couinaud's segmentectomy. This multicenter study aimed to identify the conditions of non‐HLH that satisfy equivalent technical difficulties to HLH. Methods: Between 2018 and 2021, 595 first open hepatectomies without biliary reconstruction (374 HLHs and 221 non‐HLHs) were performed in the five institutions. Non‐HLHs belonging to at least one of the three conditions; depth of hepatectomy ≥5 cm, number of resections ≥3 locations and at least one location with a depth of hepatectomy ≥3 cm, and hepatectomy involving the paracaval portion of the caudate lobe was proposed as the candidate for difficult non‐HLH. The technical difficulty was estimated by the operative time and blood loss. Results: Difficult non‐HLHs were neither associated with shorter operative time (373 min vs. 354 min, p =.184) nor lesser blood loss than those with HLHs (503 mL vs. 436 mL, p =.126). Postoperative complications such as Clavien‐Dindo classification grade III or more were not significant between the two groups (18.6% vs. 13.4%, p = 0212). Conclusions: Difficult non‐HLHs were associated with no lesser technical difficulty than those with HLH. [ABSTRACT FROM AUTHOR]