TM surface-wave power combining by a planar active-lens amplifier

Power combining of TM surface waves by a planar active-lens amplifier is the subject of this paper. An amplifier gain of 11 dB at 8.25 GHz with a 3-dB bandwidth of 0.65 GHz has been demonstrated. Gain is measured from input to output connector to facilitate comparisons with more conventional amplifiers. Measurements of output power versus input power are also presented. The amplifier behaved in a linear manner and no problems with spurious oscillations were encountered. Construction of the amplifier is compatible with planar fabrication technologies. A key component of the combiner is a microstrip-fed Yagi-Uda slot-array antenna for TM surface-wave excitation of a thick dielectric slab. Design and optimization guidelines for the antenna are presented as well as detailed spectral-domain and finite-difference time-domain (FDTD) analysis results. Measured and simulation results show an input return loss and front-to-back ratio better than 10 dB over a 5% bandwidth. Calculated and measured results for the fields radiated by the antenna confirm forward radiation of the dominant TM mode in the thick dielectric slab. Integration of the computed radiated fields shows the antenna has a surface-wave launching efficiency of 85%     

Profiling of the Beneficial and Potentially Harmful Components of Trichodesma indicum Seed and Seed Oil Obtained by Ultrasound-Assisted Extraction

The beneficial and potentially harmful bioactive components in the seeds and seed oil of Trichodesma indicum L. (Boraginaceae) were investigated in the present study. The T. indicum seeds were rich in oil (29.0%), phenolic compounds (PC, 1881.2 mg per 100 g), and pyrrolizidine alkaloids (PA, 2,702,338 ng g⁻¹). Seven PC were identified in T. indicum seeds by liquid chromatography-quadrupole-time-of-flight mass spectrometry system (LC-Q-TOF-MS). Rosmarinic acid (67%) and isomers of salvianolic acid B/E/L (26%) were the main phenolics, while melitric acid A and sebestenoid C/D constituted 6% and 1%, respectively. Only a minor part of the total PC and PA was transferred from the seeds into the oil fraction during the extraction procedure (<0.03%). The T. indicum seed oil was predominated by the following polyunsaturated fatty acids (PUFA):linoleic (23.2%), γ-linolenic (6.0%), α-linolenic (26.8%), and stearidonic (5.9%). High levels were also observed for oleic (26.7%) and palmitic (7.4%) acids. Additionally, notable amounts of γ-tocopherol (92% of total tocochromanols) and β-sitosterol (53% of total sterols) were found in T. indicum seed oil. The total content of tocochromanols, sterols, and carotenoids in T. indicum seed oil was 102.7, 236.0, and 0.6 mg per 100 g oil, respectively. Among 10 detected hepatotoxic PA in T. indicum seeds, intermedine/lycopsamine/indicine (90.9%), intermedine N-oxide (4.9%), and lycopsamine N-oxide (4.1%) consisted 99.9% of the total PA concentration. The T. indicum seeds should be used carefully due to the presence of PA.