Carbon Nanotube and Carbon Fibre Based Radiation Dosimetry

The principle of radiobiology and, hence, clinical outcomes in radiotherapy are inherently dependent on accurate radiation dosimetry. Over the last few decades, ionization chambers, thermoluminescence dosimeters (TLDs), film dosimeters, and semiconducting dosimeters have been commonly used in radiotherapy. However, the shortcomings of each type of dosimeter limit their applications for in vivo radiation measurements for provision of accurate and precise dosimetric information in real-time. The objective of this thesis is to explore a new generation of radiation dosimeters by using state-of-the-art nanomaterials and technologies to realize real-time monitoring of dose delivery in radiotherapy. This thesis investigates the use of carbon nanotubes (CNTs) and carbon fibres as sensing materials for dosimetric measurements. First, a parallel plate ionization chamber with CNT electrodes was designed to study the ionization collection efficiency of the CNTs. The prototype chamber had two stainless steel electrodes, which were customized to accommodate the CNT samples. Experiments, such as saturation characteristics, linearity, and electrode separation, were performed to characterize the prototype chamber. Secondly, dosimeters based on the resistance change of CNTs and carbon fibres were studied. The proposed dosimeters, based on carbon fibre sheets and CNT films, were designed and fabricated. Dose rate, dose, and field size measurements were carried out to evaluate these novel dosimeters that were able to provide dose rate and dose information at the same time. Thirdly, a transparent and flexible CNT-based film dosimeter was investigated. The flexible dosimeter can perform dosimetric measurements when it was bent to fit the curvature of the measured surface. Finally, a dosimeter array system, consisting of a CNT-based film dosimeter array, a readout circuit, and user interface software, was designed and implemented. The array with the parallel electrode structure and a 3 × 3 mm^2 sensing area for each pixel provided good signal responses. The array system displayed excellent repeatability in the measurements.1 yea

Overview of Multi-source Parameter Estimation and Jamming Mitigation for Monopulse Radars

Monopulse is a mainstream technique used to acquire the angle information about active radar systems that are widely used in air defense warning, target tracking, and precision guidance. This study briefly reviews the development history of the monopulse theory and technology for the main-lobe multi-source condition. The importance of several key technologies within multi-source parameters estimation and multisource jamming mitigation is also summarized. Finally, the future development of monopulse technology to resolve the problem of multi-source jamming is considered

Discrete Spectrum cover Signal Waveform Design and Generation Method

Radio Frequency-screen is one of the earliest radar active antijamming measures. It achieves antijamming by transmitting cover pulses of different frequencies before the radar pulse signal to induce enemy jammers. As the demand for antijamming measures has become increasingly urgent in recent years, Radio Frequency-screen technology has been further developed. The most representative is the use of discontinuous spectrum signals as a cover signal. However, energy utilization for sending the cover signal can be improved further. To address this problem, this paper proposes a discrete spectrum cover signal based on the discontinuous spectrum cover signal and establishes the waveform design function under the joint constraint of constant modulus and spectral amplitude. The cover signal with discrete spectrum and energy aggregation is generated using the Alternating Direction Method of Multipliers (ADMM) and spectrum shaping algorithm solution. The simulation results show that the discrete spectrum cover signal has a higher spectral amplitude of approximately 5～12 dB than the discontinuous-spectrum cover signal for the same energy and bandwidth. Moreover, the discrete spectrum cover signal can cover a larger spectral range with the same energy and close spectral amplitude, realizing a better antijamming cover effect

Genome-Wide Analysis Reveals Stress and Hormone Responsive Patterns of JAZ Family Genes in Camellia Sinensis

JAZ (Jasmonate ZIM-domain) proteins play pervasive roles in plant development and defense reaction. However, limited information is known about the JAZ family in Camellia sinensis. In this study, 12 non-redundant JAZ genes were identified from the tea plant genome database. Phylogenetic analysis showed that the 12 JAZ proteins belong to three groups. The cis-elements in promoters of CsJAZ genes and CsJAZ proteins interaction networks were also analyzed. Quantitative RT–PCR analysis showed that 7 CsJAZ genes were preferentially expressed in roots. Furthermore, the CsJAZ expressions were differentially induced by cold, heat, polyethylene glycol (PEG), methyl jasmonate (MeJA), and gibberellin (GA) stimuli. The Pearson correlations analysis based on expression levels showed that the CsJAZ gene pairs were differentially expressed under different stresses, indicating that CsJAZs might exhibit synergistic effects in response to various stresses. Subcellular localization assay demonstrated that CsJAZ3, CsJAZ10, and CsJAZ11 fused proteins were localized in the cell nucleus. Additionally, the overexpression of CsJAZ3, CsJAZ10, and CsJAZ11 in E. coli enhanced the growth of recombinant cells under abiotic stresses. In summary, this study will facilitate the understanding of the CsJAZ family in Camellia sinensis and provide new insights into the molecular mechanism of tea plant response to abiotic stresses and hormonal stimuli