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Objective In neuroendovascular treatment, there are many opportunities to guide multiple catheters into the intracranial blood vessels. We report the relationship between two microcatheters according to the guiding order with experimental in vitro studies. Materials and Methods We hypothesize that in a bent blood vessel such as a paraclinoid region of the internal carotid artery, the catheter that was first guided tended to pass through the inside, and the catheter that was guided later tended to pass through the outside. The in vitro verification was performed using a microcatheter and a balloon catheter in a silicone vascular aneurysmal model. Results As a result, it was found that the two catheters were arranged according to our hypothesis. This finding was also observed during the actual operation of balloon-assisted coil embolization. Conclusion The positional relationship between the two catheters according to the navigation order is very important, in particular during balloon-assisted coiling and stent-assisted coiling via a jailed microcatheter. [ABSTRACT FROM AUTHOR]

Hands-on training is a crucial part of education in neuroendovascular treatment to ensure safe and rapid acquisition of techniques. However, there is a significant gap between training and actual clinical practice. This study will introduce innovations for more practical thrombus retrieval training that was developed in this process. A Smart Vascular Model 3 in 1 was used. A pink pseudothrombus was inserted into the M1 (horizontal segment of the middle cerebral artery) section of the model. Then, a "red underlay" purchased at a stationery store was placed to cover the proximal part of M1 and beyond so that the pseudothrombus was not visible. The thrombus was retrieved during training by looking for the location of the thrombus based on the behavior and resistance of the tip of the guidewire and deployment of the stent retriever. The participants were required to have detailed observation skills and precise manipulation skills using a red film to prevent the direct visualization of the pseudothrombus. The implementation of this innovation to the previous hands-on training made the training more practical and effective. If the exact thrombus location can be determined by the behavior of the wire tip, the device's capabilities can be maximized, and rapid retrieval can be expected. It could also reduce complications, as unnecessary peripheral guidance of the device could be avoided. [ABSTRACT FROM AUTHOR]

Objective We noticed that the X-ray absorption value of the tip of each microcatheter used for aneurysm treatment varied from product to product. We hypothesized that the differences were caused by variations in the metal's density braid, which could be related to the ability of the tip to retain its shape. Methods The X-ray absorption value of each microcatheter tip was measured. Next, heat forming was performed using a shaping mandrel at 6 mm and 90 degrees to determine whether there was a correlation between the X-ray absorption value and the forming angle. Next, the optimal mandrel angle for forming each microcatheter at 90 degrees was investigated. We also examined the shape retention after 20 times wire insertions into each microcatheter. Conclusion It was found that the higher the X-ray absorption value, the harder it was for the microcatheter to be formed. The mandrel angle required to form 90 degrees was determined by the X-ray absorption value. The higher the X-ray absorption value, the higher the shape retention of the tip shape. The heat formation and shape-retention conditions of the microcatheter tip were correlated with the X-ray absorption value of the metal braid. Even for unknown microcatheters, the optimum shaping conditions can be inferred from the X-ray absorption value. [ABSTRACT FROM AUTHOR]

Extraction of As(III) from hydrochloric acid solution using various solvents on the basis of ion solvation has been reported, but a theoretical framework to describe the suitability of solvents for extraction has not been systematized. In this study, comprehensive extraction tests for As(III) using a variety of organic solvents were conducted to clarify the requirements for solvents to extract As(III). From the results of initial screening tests, various aromatics, ethers, and ketones were rated as candidates for the extraction of As(III) at high HCl concentrations, whereas aliphatic hydrocarbons were excluded. Many solvents showed high extraction capacity for As(III) to give organic fraction concentrations of 150 mM or higher. The logP value (P = partitioning coefficient between n-octanol and water) within a solvent class showed some correlation with extractability of As(III) but the correlation was invalid across solvent types. High correlation was shown between the Hansen solubility parameters of the solvents and As(III) extractability: Twenty of 22 solvents (90.9%) were appropriately classified as valid or invalid for the extraction of As(III) based on the Hansen sphere. 2-Nonanone was recommended as an ideal solvent for As(III) extraction because of its good balance between high extractability and its desirable physical properties for industrial operations. As(III) was quantitatively stripped from 2-nonanone into water with a concentration factor of 22.6. [ABSTRACT FROM AUTHOR]

The COVID-19 pandemic has demanded a change in learning modalities, which led us to develop a remote personal training system for clinicians performing neuroendovascular procedures. A portable vascular model designed for practicing catheter navigation guidance, thrombus retrieval, and intracranial aneurysm coil embolisation was established. We created an environment that enabled interactive dialogue and communication across long distances using the Internet. The instructor conducted approximately 2 h of hands-on training with two to four trainees at a time. Despite the restrictions enforced by the Government of Japan due to the COVID-19 pandemic, 17 online hands-on training were successfully conducted throughout Japan over 1 year for a total of 48 trainees. The developed remote training programme, to avoid the aggregation of a large number of trainees at a developed time, proved to be at par with the conventional learning system. The training was well-received since the operation time was longer and the question and answer sessions were more fulfilling compared to the conventional format in which a group of trainees had got a brief opportunity to receive actual hands-on experience. [ABSTRACT FROM AUTHOR]

Neuroendovascular catheterization using fluoroscopy poses the problem to operators and staffs of cumulative radiation exposure. To solve this problem, we are developing a remote-controlled master-slave robot. Because a wire-like elongated treatment device is inserted into a blood vessel using a catheter, the robot requires a sensor to detect the insertion force of the wire. The proposed sensor is integrated into a robot installed in an X-ray fluoroscopy room that is remotely controlled from another room. The features of this sensor include measurement of the insertion force with sufficient accuracy, simple wire attachment, and an inexpensive disposable sensor head, rendering it very suitable for practical application. In this paper, we report on these features, as well as the results of a practical test of the sensor using a cerebrovascular model. [ABSTRACT FROM AUTHOR]

A new ternary sodium magnesium bismuthide, NaMgBi, has been synthesized from the constituent metals, and its crystal structure was determined by single-crystal X-ray diffraction. NaMgBi crystallizes in a tetragonal PbFCl-type structure corresponding to the space group P4/nmm, where Z = 2, a = 4.7123(4) and c = 7.8158(7) Å. The structure is composed of layers formed by edge-sharing Bi tetrahedra centered with Mg stacked in the c-axis direction, and these layers sandwich the Na atoms. First-principles computations based on density functional theory calculations have verified that the most stable atomic configuration is the one in which the Na and Mg atoms occupy the 2a and 2c sites, respectively. The electrical resistivity measured for a sintered polycrystalline sample of NaMgBi with a relative density of 70% was found to gradually decrease from 868 to 26.4 mΩ cm upon increasing the temperature from 297 to 506 K, and the Seebeck coefficient decreased from 273 to 180 μV K−1 upon increasing the temperature from 298 to 496 K. Electronic structure calculations have revealed that NaMgBi must be a semiconductor with a small band gap of ∼0.1 eV. [ABSTRACT FROM AUTHOR]