Modeling the effects of aluminum and ammonium perchlorate addition on the detonation of the high explosives C_4H_8O_8N_8 (HMX) and C_3H_6O_6N_6(RDX)

Metalized high explosives effectively tailor the explosion impulse at lowered detonation pressures of common high performance explosives such as C_3H_6O_6N_6 (RDX) and C_4H_8O_8N_8 (HMX). The presence of aluminum (Al) with and without ammonium perchlorate (AP) allows the subsequent burning for longer and sustained reactions of enhanced blast explosives. The modeling of reaction rate laws for three explosives with varied amounts of Al, AP, RDX, and HMX is reported. The model validation included the rate stick test for understanding the explosive reaction of the three samples and the large-scale gap test for determining their ignition sensitivity. The experimental results confirmed the accuracy of the model in simulating the shock sensitivity and the size effects before detonation failure. The effect of enhanced blast of these explosives in the presence of Al and AP is also reported

ACLS: Adaptive and Conditional Label Smoothing for Network Calibration

We address the problem of network calibration adjusting miscalibrated confidences of deep neural networks. Many approaches to network calibration adopt a regularization-based method that exploits a regularization term to smooth the miscalibrated confidences. Although these approaches have shown the effectiveness on calibrating the networks, there is still a lack of understanding on the underlying principles of regularization in terms of network calibration. We present in this paper an in-depth analysis of existing regularization-based methods, providing a better understanding on how they affect to network calibration. Specifically, we have observed that 1) the regularization-based methods can be interpreted as variants of label smoothing, and 2) they do not always behave desirably. Based on the analysis, we introduce a novel loss function, dubbed ACLS, that unifies the merits of existing regularization methods, while avoiding the limitations. We show extensive experimental results for image classification and semantic segmentation on standard benchmarks, including CIFAR10, Tiny-ImageNet, ImageNet, and PASCAL VOC, demonstrating the effectiveness of our loss function.Comment: Accepted to ICCV 2023 (Oral presentation

Optimal view detection for ultrasound-guided supraclavicular block using deep learning approaches

Abstract Successful ultrasound-guided supraclavicular block (SCB) requires the understanding of sonoanatomy and identification of the optimal view. Segmentation using a convolutional neural network (CNN) is limited in clearly determining the optimal view. The present study describes the development of a computer-aided diagnosis (CADx) system using a CNN that can determine the optimal view for complete SCB in real time. The aim of this study was the development of computer-aided diagnosis system that aid non-expert to determine the optimal view for complete supraclavicular block in real time. Ultrasound videos were retrospectively collected from 881 patients to develop the CADx system (600 to the training and validation set and 281 to the test set). The CADx system included classification and segmentation approaches, with Residual neural network (ResNet) and U-Net, respectively, applied as backbone networks. In the classification approach, an ablation study was performed to determine the optimal architecture and improve the performance of the model. In the segmentation approach, a cascade structure, in which U-Net is connected to ResNet, was implemented. The performance of the two approaches was evaluated based on a confusion matrix. Using the classification approach, ResNet34 and gated recurrent units with augmentation showed the highest performance, with average accuracy 0.901, precision 0.613, recall 0.757, f1-score 0.677 and AUROC 0.936. Using the segmentation approach, U-Net combined with ResNet34 and augmentation showed poorer performance than the classification approach. The CADx system described in this study showed high performance in determining the optimal view for SCB. This system could be expanded to include many anatomical regions and may have potential to aid clinicians in real-time settings. Trial registration The protocol was registered with the Clinical Trial Registry of Korea (KCT0005822, https://cris.nih.go.kr )

Radiation Damage of Polydimethylsiloxane and Polyimide by X-ray Free-Electron Laser

Featured Application: Our results provide insight into the material selection and directions to pursue in developing sample delivery devices used in XFEL studies. A crystal delivery system is essential in serial femtosecond crystallography experiments using an X-ray free-electron laser (XFEL). Investigating the XFEL-induced radiation damage to materials potentially applicable to sample delivery devices is vital for developing a sample delivery system. In this study, we investigated the radiation damage caused by an XFEL to polydimethylsiloxane (PDMS) and polyimide (PI), which are widely used as sample delivery materials in synchrotron X-rays. Upon XFEL exposure, the PDMS film produced irregularly shaped and sized holes, whereas the PI film produced relatively regular shaped and sized holes. When XFELs were exposed to the channel of the PDMS-based microfluidic device, holes were generated on the film by the radiation damage and the microfluidic device and the internal channel region were structurally destroyed. The PI-based microfluidic device experienced no structural destruction, except for the holes generated by the XFEL. However, as the XFELs were continuously exposed, bubbles generated from the solution due to radiation damage; the accumulation of these bubbles interfered with the path of the inner channel of the microfluidic device. Our results will not only help understand the phenomenon of radiation damage of PDMS and PI films by XFEL, but also provide insight into the directions to pursue in developing applications of PDMS and PI films in XFEL studies. © 2022 by the authors.11Nsciescopu

Application of a high-throughput microcrystal delivery system to serial femtosecond crystallography

Microcrystal delivery methods are pivotal in the use of serial femtosecond crystallography (SFX) to resolve the macromolecular structures of proteins. Here, the development of a novel technique and instruments for efficiently delivering microcrystals for SFX are presented. The new method, which relies on a one-dimensional fixed-target system that includes a microcrystal container, consumes an extremely low amount of sample compared with conventional two-dimensional fixed-target techniques at ambient temperature. This novel system can deliver soluble microcrystals without highly viscous carrier media and, moreover, can be used as a microcrystal growth device for SFX. Diffraction data collection utilizing this advanced technique along with a real-time visual servo scan system has been successfully demonstrated for the structure determination of proteinase K microcrystals at 1.85 Å resolution.11Ysciescopu

Viscous-medium-based crystal support in a sample holder for fixed-target serial femtosecond crystallography

Serial femtosecond crystallography (SFX) enables the determination of the room-temperature crystal structure of macromolecules, as well as providing time-resolved molecular dynamics data in pump-probe experiments. Fixed-target SFX (FT-SFX) can minimize sample consumption and physical effects on crystals during sample delivery. In FT-SFX studies, having a sample holder that can stably fix crystal samples is one of the key elements required for efficient data collection. Hence, development of sample holders from new materials capable of supporting various crystal sizes and shapes may expand the applications of FT-SFX. Here, a viscous-media-based crystal support in a sample holder for FT-SFX is introduced. Crystal samples were embedded in viscous media, namely gelatin and agarose, which were enclosed in a polyimide film. In the vertically placed sample holder, 10-15%(w/v) viscous gelatin and 1-4%(w/v) agarose gel stably supported crystals between two polyimide films, thereby preventing the crystals from descending owing to gravity. Using this method, FT-SFX experiments were performed with glucose isomerase and lysozyme embedded in gelatin and agarose, respectively. The room-temperature crystal structures of glucose isomerase and lysozyme were successfully determined at 1.75 and 1.80 angstrom resolutions, respectively. The glucose isomerase and lysozyme diffraction analyses were not impeded by excessive background scattering from the viscous media. This method is useful for delivering crystal samples of various sizes and shapes in FT-SFX experiments.11Nsciescopu

Reliable DC voltage generation based on the enhanced performance triboelectric nanogenerator fabricated by nanoimprinting-poling process and an optimized high efficiency integrated circuit

Intensive research on triboelectric nanogenerators (TENGs) has been established since they were first introduced, but their application as a practical power source remains to face several challenges. Herein, we report a one-step process of thermal nanoimprinting and simultaneous electric poling to increase the total energy obtained by each cycle of a TENG with a ferroelectric thermoplastic polymer. The synergetic effect generated by the resultant formation of surface topography and the enhancement of effective dipole strength is systematically verified, and a wind energy harvester with enhanced electrical output performance is demonstrated. Furthermore, this paper also presents a novel integrated circuit (IC) that can generate reliable DC voltage even when an intermittent and irregular electrical output of the TENG is supplied. In the automatic control of the moment when the electrical output of the TENG is transferred into the electronic device, the present IC shows a conversion efficiency over 70% even when the input power is about 2.5 mu W. This work intensively addresses the issues hindering the utilization of TENGs as a practical and reliable power source and thus may serve as a reference in the development of TENG-based self-powered systems in the future.11Nsciescopu