Syntheses and structural characterization of zirconium-tin and zirconium-lead binary and ternary systems

The binary zirconium-tin system was reinvestigated. The A15 phase appears to be a line phase with a Zr[subscript]4Sn composition. This phase is extremely unstable with oxygen contamination. The Zr[subscript]5Sn[subscript]3 (Mn[subscript]5Si[subscript]3-type) and Zr[subscript]5Sn[subscript]4 (Ti[subscript]5Ga[subscript]4-type) compounds are line phases below 1000°C, the latter being a self-interstitial phase of the former. ZrSn[subscript]2 is the tin-richest phase. There is an one-phase region between these phases with partial self-interstitials at high temperatures. The zirconium-lead system behaves similarly: there are an A15 phase with a Zr[subscript]~5.8Pb composition, Zr[subscript]5Pb[subscript]3 (Mn[subscript]5Si[subscript]3-type) and Zr[subscript]5Pb[subscript]4 (Ti[subscript]5Ga[subscript]4-type) compounds, and a high temperature solid solution between Zr[subscript]5Pb[subscript]\u3e3.5 and Zr[subscript]5Pb[subscript]4 from below 1000°C; however, the ZrSn[subscript]2 analogue is not formed;The Mn[subscript]5Si[subscript]3-type phases in these systems can accommodate third elements interstitially to form stoichiometric compounds Zr[subscript]5Sn[subscript]3Z (Z = B, C, N, O, Al, Si, P, S, Cu, Zn, Ga, Ge, As and Se) and Zr[subscript]5Pb[subscript]3Z (Z = Al, Si, P, S, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Ag, Cd, In, Sn, Sb and Te) as well as their self-interstitial derivatives. The stoichiometric nature of most of the interstitial phases was confirmed by structure analyses of single crystals for Z = C, O, and Ge in Zr[subscript]5Sn[subscript]3Z and Z=Zn and Pb in Zr[subscript]5Pb[subscript]3Z and of powder for Zr[subscript]5Sn[subscript]3Ga as well as by synthetic considerations. The crystal structures show strong zirconium-interstitial interactions. A substoichiometric interstitial phase also exists for Zr[subscript]5Sn[subscript]3S[subscript] x (0.5 ≤ x ≤ 1.0). Vapor phase transport reactions for Z = Al, Zn, and Pb in Zr[subscript]5Pb[subscript]3Z were successful with the transporting agent ZrCl[subscript]4;The systems Zr-Sn-T, T = Fe, Co and Ni, did not produce stoichiometric interstitial phases Zr[subscript]5Sn[subscript]3T. Instead, the interstitial phases for these elements are formed only with excess tin that partially occupies the interstitial site together with a T element. Reducing the amount of tin in these systems yields two new phases; Zr[subscript]5Sn[subscript] 2 + xFe[subscript] 1 - x (0 ≤ x ≤ 0.28) (W[subscript]5Si[subscript]3-type) and Zr[subscript]6Sn[subscript]2Fe (Zr[subscript]6Al[subscript]2Co-type) as characterized by X-ray single crystal analyses. A cobalt analogue for the latter was also synthesized. ftn*DOE Report IS-T-1505. This work was performed under contract No. W-7405-Eng-82 with the U.S. Department of Energy

Behavior of Connections Between SHS Columns & W-section Beams

Connections between SHS (Square Hollow Section) columns and W-section beams are generally fabricated by welding with or without endplates in the factory. These welded connections possess some finite degree of rotational stiffness which falls between fully rigid and ideally pinned joints. The influence of partially restrained connections on structural response not only changes the moment distribution but also increases frame drift. In this paper, a series of connection tests joining SHS column and W-section beam were executed and the test results compared with theoretical values. A method to utilize nonlinear moment-rotation relations of beam-to-column connections in steel framed structures is proposed. For the problem of contact in endplate-type connections, a simple and efficient method is also introduced

Conventional Vickers and true instrumented indentation hardness determined by instrumented indentation tests

We evaluate Vickers hardness and true instrumented indentation test (IIT) hardness of 24 metals over a wide range of mechanical properties using just IIT parameters by taking into account the real contact morphology beneath the Vickers indenter. Correlating the conventional Vickers hardness, indentation contact morphology, and IIT parameters for the 24 metals reveals relationships between contact depths and apparent material properties. We report the conventional Vickers and true IIT hardnesses measured only from IIT contact depths; these agree well with directly measured hardnesses within ±6% for Vickers hardness and ±10% for true IIT hardness

Redirected Walking in Infinite Virtual Indoor Environment Using Change-blindness

We present a change-blindness based redirected walking algorithm that allows a user to explore on foot a virtual indoor environment consisting of an infinite number of rooms while at the same time ensuring collision-free walking for the user in real space. This method uses change blindness to scale and translate the room without the user's awareness by moving the wall while the user is not looking. Consequently, the virtual room containing the current user always exists in the valid real space. We measured the detection threshold for whether the user recognizes the movement of the wall outside the field of view. Then, we used the measured detection threshold to determine the amount of changing the dimension of the room by moving that wall. We conducted a live-user experiment to navigate the same virtual environment using the proposed method and other existing methods. As a result, users reported higher usability, presence, and immersion when using the proposed method while showing reduced motion sickness compared to other methods. Hence, our approach can be used to implement applications to allow users to explore an infinitely large virtual indoor environment such as virtual museum and virtual model house while simultaneously walking in a small real space, giving users a more realistic experience.Comment: https://www.youtube.com/watch?v=s-ZKavhXxd

Ultrasound-guided supraclavicular brachial plexus block in pediatric patients -A report of four cases-

Supraclavicular brachial plexus blocks are not common in pediatric patients due to the risk of pneumothorax. Ultrasonography is an important tool for identifying nerves during regional anesthesia. Directly visualizing the target nerves and monitoring the distribution of the local anesthetic are potentially significant. In addition, ultrasound monitoring helps avoid complications, such as inadvertent intravascular injection or pneumothorax. This paper reports four cases of pediatric patients who received ultrasound-guided supraclavicular brachial plexus block for upper limb surgery

Preoperative and Postoperative Evaluation of Multiple Giant Coronary Aneurysms by the Use of Coronary CT Angiography with 64-MDCT: A Case of Multiple Giant Coronary Aneurysms Treated with Aneurysmectomy and Coronary Artery Bypass Surgery

A coronary artery aneurysm is an uncommon disorder and is seen as a characteristic dilatation of a localized portion of the coronary artery. Clinical manifestation of a coronary artery aneurysm varies from an asymptomatic presentation to sudden death of a patient. Although coronary aneurysms are typically diagnosed by the use of coronary angiography, a new generation of coronary 64-slice multidetector computed tomography (64-MDCT) scanners have successfully been used for evaluating this abnormality in a noninvasive manner. In the present case, we performed coronary 64-MDCT scanning preoperatively and postoperatively on a patient with multiple giant coronary aneurysms. The use of coronary 64-MDCT may provide an evaluation technique not only for diagnosis but also for follow-up after surgery for this condition