分类： 物理学 >> 核物理学 提交时间： 2023-07-12
摘要： To guarantee the exact proton dose applied to patients and ensure treatment safety while disrupting and destroying tumor cells, it is essential to accurately monitor the proton beam current in real-time during patient treatment. Because clinical treatment requires a proton beam current in the ~nA range, nondestructive beam current monitors (BCMs) are preferred to minimize the degradation of beam quality. However, this poses significant challenges in accurately monitoring such extremely low beam intensities. This study proposes a cavity-type BCM equipped with a dielectric plate to reduce its dimensions and achieve sufficient measurement sensitivity for practical requirements. A prototype cavity BCM was fabricated, and offline testing was performed using a metal wire to simulate the beam to study its performance. Both the simulation and experimental results showed that the cavity BCM could measure ultralow proton beam currents with a resolution up to 0.03 nA.
分类： 生物学 >> 生物物理学 提交时间： 2016-05-12
Wang, Yan
Wang, Mingxia
Wang, Jian
Xu, Tao
Yin, Sanwen
Jang, Richard
Xue, Zhidong
Jang, Richard
Xu, Tao
摘要： Neuropeptides play a variety of roles in many physiological processes and serve as potential therapeutic targets for the treatment of some nervous-system disorders. In recent years, there has been a tremendous increase in the number of identified neuropeptides. Therefore, we have developed NeuroPep, a comprehensive resource of neuropeptides, which holds 5949 non-redundant neuropeptide entries originating from 493 organisms belonging to 65 neuropeptide families. In NeuroPep, the number of neuropeptides in invertebrates and vertebrates is 3455 and 2406, respectively. It is currently the most complete neuropeptide database. We extracted entries deposited in UniProt, the database (www.neuropeptides.nl) and NeuroPedia, and used text mining methods to retrieve entries from the MEDLINE abstracts and full text articles. All the entries in NeuroPep have been manually checked. 2069 of the 5949 (35%) neuropeptide sequences were collected from the scientific literature. Moreover, NeuroPep contains detailed annotations for each entry, including source organisms, tissue specificity, families, names, post-translational modifications, 3D structures (if available) and literature references. Information derived from these peptide sequences such as amino acid compositions, iso-electric points, molecular weight and other physicochemical properties of peptides are also provided. A quick search feature allows users to search the database with keywords such as sequence, name, family, etc., and an advanced search page helps users to combine queries with logical operators like AND/OR. In addition, user-friendly web tools like browsing, sequence alignment and mapping are also integrated into the NeuroPep database.
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