Effects of particle size and content of RDX on burning stability of RDX-based propellants

Abstract Particle size and content of RDX are the two main factors that affect the burning stability of RDX-based propellants. However, these effects and the corresponding mechanisms are still controversial. In this work, we investigated the physicochemical processes during burning and the corresponding mechanisms through the technologies of structure compactness analysis on the base of voidage measurement and theoretical interfacial area estimation, apparent burning rate measurement using closed vessel (CV) and extinguished burning surface characterization relying on interrupted closed vessel (ICV) and scanning electron microscope (SEM). The results indicate that the voidage increased with the increase of RDX content and particle size due to the increasing interfacial area and increasing interface gap size, respectively. The apparent burning rate increased with the increase of RDX particle size because of the decreasing RDX specific surface area on the burning surface, which could decrease the heat absorbing rates of the melting and evaporation processes of RDX in the condensed phase. Similarly, the apparent burning rate decreased with the increase of RDX content at pressures lower than around 55 MPa due to the increasing RDX specific surface area. Whereas, an opposite trend could be observed at pressures higher than around 55 MPa, which was attributed to the increasing heat feedback from the gas phase as the result of the increasing propellant energy. For propellants containing very coarse RDX particles, such as 97.8 and 199.4 μm average size, the apparent burning rate increased stably with a flat extinguished surface at pressures lower than around 30 MPa, while increased sharply above around 30 MPa with the extinguished surface becoming more and more rugged as the pressure increased. In addition, the turning degree of u-p curve increased with the increase of coarse RDX content and particle size, and could be reduced by improving the structure compactness

Electromagnetically induced transparency of interacting Rydberg atoms with two-body dephasing

We study electromagnetically induced transparency in a three-level ladder type configuration in ultracold atomic gases, where the upper level is an electronically highly excited Rydberg state. An effective distance dependent two-body dephasing can be induced in a regime where dipole-dipoles interaction couple nearly degenerate Rydberg pair states. We show that strong two-body dephasing can enhance the excitation blockade of neighboring Rydberg atoms. Due to the dissipative blockade, transmission of the probe light is reduced drastically by the two-body dephasing in the transparent window. The reduction of transmission is accompanied by a strong photon-photon anti-bunching. Around the Autler-Townes doublets, the photon bunching is amplified by the two-body dephasing, while transmission is largely unaffected. Besides relevant to the ongoing Rydberg atom studies, our study moreover provides a setting to explore and understand two-body dephasing dynamics in many-body systems

Effect of wooden breast degree on lipid and protein oxidation and citrate synthase activity of chicken pectoralis major muscle

In this study, 154 pectoralis major breast muscles from three chicken age groups were separated into different severity levels of wooden breast condition by manual palpation to investigate the changes of lipid and protein oxidation and citrate synthase activity. TBARS values, carbonyl contents and loss of free thiol groups were greater (P < 0.05) in the superficial (ventral) part of severe wooden breast samples, whereas no clear change was found in the deep (dorsal) part. Mitochondrial citrate synthase activity declined with increasing severity of wooden breast myopathy. Both bird age and wooden breast degree showed significant main effects on these indicators, while no interaction effect was observed. Moreover, there were significant correlations between lipid and protein oxidation and citrate synthase activity. Here, we propose a hypothesis that lipid and protein damages and mitochondrial dysfunction is linked to the aggravation of the wooden breast myopathy.Peer reviewe

Using Machine Learning to Improve PDF Uncertainties

Parton Distribution Functions (PDFs) contribute significantly to the uncertainty on the determination of the top-quark pole mass and other precision measurements at the Large Hadron Collider (LHC). It is crucial to understand these uncertainties and reduce them to obtain the next generation of precision measurements at the LHC. The region of high momentum fraction offers an opportunity to make improvements to the PDFs. This study uses machine learning techniques in $t\bar{t}$ production to target this region of the PDF set and has potential to significantly reduce its uncertainty.Comment: Poster presentation at the 16th International Workshop on Top Quark Physics (Top2023), 24-29 September 202

Yellow–colored mesoporous pure titania and its high stability in visible light photocatalysis

AbstractYellow–colored pure titania with a mesoporous structure was prepared by the aggregate of titania nanocrystals, which were stabilized by exfoliated titanate nanosheets via an electrostatic interaction. X–ray diffraction patterns and images of transmission electron microscope confirm that titanate sheets are randomly dispersed into the assembled titania nanocrystals without forming any self–restacked phase. This nanocrystals–nanosheets composite exhibits a mesoporous structure with pore size of ~6.5nm and surface area of 236.3m2g−1. Greatly different from the UV–responded properties of titania nanocrystals and titanate nanosheets, the absorption edge of nanocomposite red–shifts to visible light region. The visible light photocatalytic tests demonstrate that this nanocomposited titania shows excellent activity for the degradation of organic dyes, as well as a colorless organic pollutant of 2, 4–dichlorophenol. The possible photocatalytic mechanism that photogenerated holes as the mainly oxidant species in photocatalysis is proposed based on the trapping experiments of hydroxyl radicals or photogenerated holes. Moreover, as the nanocomposite depicts an extreme stability, no obvious deactivation occurs after five cycles

Monitoring of atopic dermatitis using leaky coaxial cable

In our daily life, inadvertent scratching may increase the severity of skin diseases (such as atopic dermatitis, etc.). However, people rarely pay attention to this matter, so the known measurement behavior of the movement is also very little. Nevertheless, the behavior and frequency of scratching represent the degree of itching, and the analysis of scratching frequency is helpful to the doctor's clinical dosage. In this paper, a novel system is proposed to monitor the scratching motion of a sleeping human body at night. The core device of the system are just a Leaky coaxial cable (LCX) and a router. Commonly, LCX is used in the blind field or semi blind field in wireless communication. The new idea is that the leaky cable is placed on the bed, then the state information of physical layer of wireless communication channels is acquired to identify the scratching motion and other small body movements in the human sleep process. The results show that it can be used to detect the movement and its duration. Channel state information (CSI) packet is collected by card installed in the computer based on the 802.11n protocol. The characterization of the scratch motion in the collected channel state information is unique, so it can be distinguished from the wireless channel amplitude variation trend

Authentication in Millimeter-Wave Body-Centric Networks Through Wireless Channel Characterization

Advent of 5G technologies has ensued in massive growth of body-centric communications (BCCs), especially at millimeter-wave (mm-wave) frequencies. As a result, the portable/handheld terminals are becoming more and more “intelligent” but not without the cost of being less secure. Improved authentication measures need to be explored, as effective identity authentication is the first level of security in these devices. This paper presents a novel keyless authentication method exploiting wireless channel characteristics. Human palm has distinct transmission coefficient (S21) for each of the users and is used for in vivo fingerprint identification in this paper. A detailed channel modeling using data acquisition from real environment and empirical approach is adopted to evaluate the usability of this method. The results show that this method can provide a secure operation for the mm-wave 5G BCCs

Feasibility and safety of expandable mediastinoscopic and laparoscopic radical esophagectomy

BackgroundAt present, minimally invasive radical esophagectomy is the main surgical method for esophageal cancer treatment, but it has inherent limitations. We have developed a novel method of radical esophagectomy without thoracotomy to improve this situation, namely, by using EMLE. We evaluated the feasibility and safety of expandable mediastinoscopic and laparoscopic radical esophagectomy (EMLE) through a retrospective analysis.MethodsFrom January 2019 to June 2022, we successfully performed 106 cases of radical resection of esophageal cancer with this new surgical technique, gradually improved the surgical path, and recorded the perioperative data and postoperative complications of all patients.ResultsThe operation was successfully performed in all patients except for two patients who required a switch to open surgery. The mean operation time was 171.11 ± 33.29 min and the mean intraoperative blood loss was 93.53 ± 56.32 ml. The mean number of removed lymph nodes was 23.59 ± 5.42. The postoperative complications included pneumonia (3.77%), recurrent laryngeal nerve palsy (1.89%), anastomotic leak (14.15%), pleural effusion (5.66%), chylothorax (2.83%), and reoperation (4.72%). All complications were graded I–III per the Clavien–Dindo classification. No perioperative death was recorded.ConclusionExpandable mediastinoscopic and laparoscopic radical esophagectomy is feasible for radical resection of esophageal cancer, with good therapeutic effect and safety. Because of its minimal impact on patients and convenient operation, it is a novel surgical option for patients with esophageal cancer and is expected to become a standard surgical method for radical esophagectomy in the future

Helium bubble nucleation in Laser Powder Bed Fusion processed 304L stainless steel

The interest in application of Additive Manufacturing (AM) to nuclear industry stems not only from the benefits of design freedom and shortened lead time, but also from the possibility of enhancing the performance through microstructure control. One of the most important requirements for in-core structural material in nuclear power plants is helium resistance. The Laser Powder Bed Fusion (LPBF) processed 304L stainless steel possesses strong defect sinks such as high densities of dislocation-surrounded sub-grains and dispersed nano-inclusions. In this work the LPBF processed 304L in as-built and solution-annealed conditions along with a conventionally rolled counterpart were implanted with 350\ua0keV He+\ua0ion at 300\ua0\ub0C to 0.24 dpa (displacement per atom). Transmission Electron Microscopy (TEM) observations indicate significantly higher helium resistance of the as-built LPBF 304L compared to the other two samples. The sink strengths in the three samples are calculated based on the measurements of the microstructural features using simplified equations for the correlation between microstructural characteristics and helium tolerance. Based on the calculation, the cellular sub-grains and the dispersed nano-inclusions are the primary and secondary contributors to the helium resistance of LPBF 304L steel

Experience and Lessons Learned in the Treatment of Transforming Small Cell Neuroendocrine Carcinoma of the Prostate: A Case Report and Literature Review

Introduction: Small cell neuroendocrine carcinoma of the prostate (SCNECP) is a rare and highly malignant tumor that commonly transforms into conventional prostate adenocarcinoma (CPAC). Most of SCNECP cases cannot be detected and diagnosed early, and SCNECP is often diagnosed when there is liver and lung metastasis. Therefore, the early detection of the process from CPAC to SCNECP is crucial. Case Report: We present a case of a 73-year-old man who was initially admitted to our hospital with metastatic CPAC. He was administered goserelin acetate 3.6 mg combined with bicalutamide tablets (50 mg) once daily for endocrine therapy and docetaxel (100 mg) combined with prednisone (5 mg) twice a day. After treatment, the prostate-specific antigen (PSA) level decreased significantly, but the CEA, CA199, and CA125 levels began to increase progressively after a short decline. However, no solid tumor recurrence was observed in multiple reexaminations. It was not until 9 months after the elevation of tumor markers that multiple metastatic lesions appeared in the liver, which finally confirmed the diagnosis of metastatic SCNECP. After chemotherapy with etoposide 360 mg combined with carboplatin 200 mg, the tumor size was significantly reduced, and tumor markers decreased. However, the remission time was only 3 months. The patient’s liver metastases continued to grow, and CEA, CA199, and CA125 levels continued to increase. Conclusion: During CPAC treatment, PSA levels continued to decrease, whereas CEA, CA199, and CA125 levels continued to increase. This suggests the possibility of the transformation of CPAC into SCNECP