Surface smoothing of additively manufactured Ti-6Al-4V alloy by combination of grit blasting and large-area electron beam irradiation

Additively manufactured (AMed) titanium products are typically produced by electron beam melting (EBM), since oxidation of titanium alloy surface can be suppressed in vacuum environment. The surface roughness of AMed titanium products becomes more than 200 µm Rz, and the very rough surface would lead to reduction in fatigue strength. Therefore, a post surface finishing process is required. Abrasive blasting is one of the common surface smoothing processes of AMed metal products. Large surface roughness can be decreased, and compressive residual stress can be introduced to the surface. However, there is a limitation to reduction of surface roughness to several µm Rz. On the other hand, it was recently found that AMed metal surface produced by powder bed fusion with laser beam could be smoothed by large-area electron beam (LEB) irradiation. However, it is difficult to smooth surface with large initial surface roughness, and a tensile residual stress may be generated on the surface. In this study, surface smoothing and change in residual stress of AMed titanium alloy (Ti-6Al-4 V) were proposed by combination of grit blasting and LEB irradiation. Surface roughness of AMed Ti-6Al-4 V alloy significantly decreases from 265 to about 2.0 µm Rz by combination of grit blasting and LEB irradiation. Reduction rate of surface roughness by LEB irradiation linearly increases with decreasing mean width of blasted surface. Influence of the mean width on smoothing effect by LEB irradiation can be explained by thermo-fluid analysis. Moreover, tensile residual stress caused by LEB irradiation can be reduced when LEB is irradiated to blasted surface

Penetration of the Optic Nerve or Chiasm by Anterior Communicating Artery Aneurysms: Three Case Reports

Although large and giant aneurysms can induce visual disturbance by compression of the anterior visual pathway, splitting and penetration of the optic apparatus are extremely rare. The authors describe three patients who underwent clipping surgery for anterior communicating artery aneurysm infiltrating into the optic nerve or chiasm. These findings were suspected on preoperative magnetic resonance imaging and confirmed at surgery. Two aneurysms were ruptured and one unruptured. The authors review the literature and discuss the mechanism of cranial nerve penetration by an aneurysm.ArticleNEURO-OPHTHALMOLOGY. 35(3):128-132 (2011)journal articl

Spontaneous Bilateral Pneumothorax in a Patient with Anorexia Nervosa: The Management of Prolonged Postoperative Air Leakage

A 24-year-old Japanese female with anorexia nervosa presented to our hospital for bilateral pneumothorax, and 12-Fr thoracostomy catheters were inserted into the bilateral pleural cavities. On hospital day 9, a thoracoscopic bullectomy was performed. However, air leakage relapsed on both sides on postoperative day 1. The air leakage on the right side was particularly persistent, and we switched the drainage to a Heimlich valve. Both lungs expanded gradually and the chest tube was removed on postoperative day 19. Passive pleural drainage might be an option for prolonged air leakage after a bullectomy in patients with anorexia nervosa

Effects of Erbium-Doped: Yttrium Aluminum Garnet (Er: YAG) Laser on Bacteremia due to Scaling and Root Planing

INTRODUCTION: The aims of the present study were: [1] to evaluate whether Erbium-Doped: Yttrium, Aluminum and Garnet (Er: YAG) laser could be a prophylactic methods against transient bacteremia during scaling and root planing (SRP) [2] to confirm the efficacies of SRP with Er: YAG laser by clinical and microbiologic evaluations.METHODS: Twenty chronic periodontitis subjects were randomly treated for quadrant SRP with either conventional hand instrument (n=10) or Er: YAG laser (n=10) monotherapy. Peripheral blood samples were drawn at baseline and 6 minutes after initiation of SRP, and were cultured for the analysis of bacteremia. Clinical measurements of full mouth plaque control record (PCR), probing pocket depth (PPD), clinical attachment level (CAL) and bleeding on probing (BOP) were made at baseline and 1 month after SRP. In addition, microbiologic analyses of subgingival samples were also performed at baseline and 1 month after SRP using the polymerase chain reaction Invader method.RESULTS: The incidence of bacteremia during SRP was 0% (0/10) in the Er: YAG laser group and 80% (8/10) in the hand instrument group, which was significantly different (P = 0.0003). All isolates from blood were facultative or obligate anaerobes and more than half of the microorganisms were species of streptococci. Intragroup comparison revealed that the mean PPD and CAL significantly decreased compared to baseline in both groups (P < 0.05). However, the percentage of BOP positive significantly decreased only in Er: YAG laser group (P = 0.005). In addition, the reductions of the subgingival bacterial counts between baseline and 1 month after SRP were also comparable between the two groups.CONCLUSION: The present study demonstrated that SRP with Er: YAG laser could not only be an alternative treatment for improvement of clinical and microorganisms situations but also a novel prophylactic method against transient bacteremia

Correlation between fabrication factor and superconducting properties of the Tl-and-Bi-based high-Tc superconductor

Large critical current densities (J(sub c)) were obtained in c axis oriented Tl-1 223/Ag composite tapes fabricated by spraying methods without a vacuum. Transport measurements at 77K under a zero field indicated a J(sub c) of 9 x 10(exp 4) A/sq cm and 7 x 10(exp 3) A/sq cm at 1T for the tapes fabricated by spray pyrolysis. The novel GPM method was also applied for Bi-2212/Ag PIT composite wire, and found to be very effective for improving the distribution of voids, which caused from the melt-solidifying process. The GPM showed a marked effect for obtaining homogeneous long wire. A 1 T class coil was successfully fabricated with monocore wire

Effect of Fullerene Encapsulation on Radial Vibrational Breathing-Mode Frequencies of Single-Wall Carbon Nanotubes

We investigate the effects of C60 fullerene encapsulation on the radial breathing mode (RBM) of semiconducting single-wall carbon nanotubes (SWCNTs) under tunable laser excitations. The changes in the RBM frequencies after C60 insertions show characteristic behavior; higher frequency shifts are observed in the case of smaller diameter tubes (dt~1.32 nm). The observed frequency shifts are satisfactorily explained by the diameter-dependent interaction between the encapsulated C60 and the host SWCNTs

Versatile Multilinked Aerial Robot with Tilting Propellers: Design, Modeling, Control and State Estimation for Autonomous Flight and Manipulation

Multilinked aerial robot is one of the state-of-the-art works in aerial robotics, which demonstrates the deformability benefiting both maneuvering and manipulation. However, the performance in outdoor physical world has not yet been evaluated because of the weakness in the controllability and the lack of the state estimation for autonomous flight. Thus we adopt tilting propellers to enhance the controllability. The related design, modeling and control method are developed in this work to enable the stable hovering and deformation. Furthermore, the state estimation which involves the time synchronization between sensors and the multilinked kinematics is also presented in this work to enable the fully autonomous flight in the outdoor environment. Various autonomous outdoor experiments, including the fast maneuvering for interception with target, object grasping for delivery, and blanket manipulation for firefighting are performed to evaluate the feasibility and versatility of the proposed robot platform. To the best of our knowledge, this is the first study for the multilinked aerial robot to achieve the fully autonomous flight and the manipulation task in outdoor environment. We also applied our platform in all challenges of the 2020 Mohammed Bin Zayed International Robotics Competition, and ranked third place in Challenge 1 and sixth place in Challenge 3 internationally, demonstrating the reliable flight performance in the fields

Preparation of a Nanoscaled Poly(vinyl alcohol)/Hydroxyapatite/DNA Complex Using High Hydrostatic Pressure Technology for In Vitro and In Vivo Gene Delivery

Our previous research showed that poly(vinyl alcohol) (PVA) nanoparticles incorporating DNA with hydrogen bonds obtained by high hydrostatic pressurization are able to deliver DNA without any significant cytotoxicity. To enhance transfection efficiency of PVA/DNA nanoparticles, we describe a novel method to prepare PVA/DNA nanoparticles encapsulating nanoscaled hydroxyapatites (HAps) prepared by high hydrostatic pressurization (980 MPa), which is designed to facilitate endosomal escape induced by dissolving HAps in an endosome. Scanning electron microscopic observation and dynamic light scattering measurement revealed that HAps were significantly encapsulated in PVA/HAp/DNA nanoparticles. The cytotoxicity, cellular uptake, and transgene expression of PVA/HAp/DNA nanoparticles were investigated using COS-7 cells. It was found that, in contrast to PVA/DNA nanoparticles, their internalization and transgene expression increased without cytotoxicity occurring. Furthermore, a similar level of transgene expression between plasmid DNA and PVA/HAp/DNA nanoparticles was achieved using in vivo hydrodynamic injection. Our results show a novel method of preparing PVA/DNA nanoparticles encapsulating HAp nano-crystals by using high hydrostatic pressure technology and the potential use of HAps as an enhancer of the transfection efficiency of PVA/DNA nanoparticles without significant cytotoxicity