ABSTRACT
The key elements used for receiving and processing signals in communication systems are the bandpass filters. Initially, a common operating mechanism was applied for the design of broadband filters, i.e., by cascading low-pass filters or high-pass filters using multiple line resonators with length quarter-half- or full-wavelength with central frequency, but using these approaches, the design topology becomes expensive and complex. The above mechanisms can be possibly overcome using a planar microstrip transmission line structure due to its simple design fabrication procedure and low cost. So, pointing out the above problems in bandpass filters such as low-cost, low insertion loss, and good out-of-band performance, this article presents a broadband filter with multifrequency suppression capability at 4.9 GHz, 8.3 GHz, and 11.5 GHz using a T-shaped shorted stub-loaded resonator with a central square ring coupled to the basic broadband filter. Initially, the C-shaped resonator is utilized for the formation of a stopband at 8.3 GHz for a satellite communication system, and then a shorted square ring resonator is added to the existing C-shaped structure for the realization of two more stopbands at 4.9 GHz and 11.5 GHz for 5G (WLAN 802.11j) communication, respectively. The overall circuit area covered with the proposed filter is 0.52 λg × 0.32 λg (λg is the wavelength of the feed lines at frequency 4.9 GHz). All the loaded stubs are folded in order to save the circuit area, which is an important requirement of next-generation wireless communication systems. The proposed filter has been analyzed using a well-known transmission line theory, even-odd-mode, and simulated with the 3D software HFSS. After the parametric analysis, some attractive features were obtained, i.e., compact structure, simple planar topology, low insertion losses of 0.4 dB over the entire band, good return loss greater than 10 dB, and independently controlled mutli stopbands, which make the proposed design unique and can be used in various wireless communication system applications. Finally, a Rogers RO-4350 substrate is selected for the fabrication of the prototype using an LPKF S63 ProtoLaser machine and then measured using a ZNB20 vector network analyzer for matching the simulated and measured results. After testing the prototype, a good agreement was found between the results.
ABSTRACT
OBJECTIVES: Radical surgery for rectal tumours has high morbidity. Local excision of such tumours can be achieved without compromising oncologic safety. However tumours that are not accessible to local excision can be approached using Transanal Minimal Invasive Surgery (TAMIS). The aim of our study was to assess feasibility of TAMIS procedure in terms of complications, operating time, resection margin positivity, hospital stay and local recurrence rate. MATERIAL AND METHODS: Forty eight patients with benign adenomas or early stage adenocarcinoma, within 4 to 12 cm from anal verge who were subjected to TAMIS over a period of 3 years were included in the study. Short and long term outcomes were assessed. RESULTS: TAMIS was performed for 36 benign adenomas and 12 adenocarcinomas, which were located at an average distance of 6.2 cm from anal verge. The mean operating time was 72 minutes. There were no intraoperative complications.1 (2.08%) patient suffered post operative bleeding, which was managed conservatively. 2 (4.16%) patients developed acute urinary retention who required indwelling catheterisation. Resection margin was positive in 3 (6.25%) benign cases. Average hospital stay was 2.7 days. Local recurrence occurred in 2 (4.16%) villous adenoma patients (after 11 and 13 months), whereas in malignant patients there was no recurrence at a follow up period ranging between 12 to 36 months. CONCLUSION: TAMIS is a safe and feasible procedure for benign tumours and early rectal cancers, located in low and middle rectum.
ABSTRACT
An optical diagnostic technique to determine the order and concentration of lithium polysulfides in lithium-sulfur (Li-S) battery electrolytes has been developed. One of the major challenges of lithium-sulfur batteries is the problem of polysulfide shuttling between the electrodes, which leads to self-discharge and loss of active material. Here we present an optical diagnostic for quantitative in situ measurements of lithium polysulfides using attenuated total reflection Fourier transform infrared (FT-IR) spectroscopy. Simulated infrared spectra of lithium polysulfide molecules were generated using computational quantum chemistry routines implemented in Gaussian 09. The theoretical spectra served as a starting point for experimental characterization of lithium polysulfide solutions synthesized by the direct reaction of lithium sulfide and sulfur. Attenuated total reflection FT-IR spectroscopy was used to measure absorption spectra. The lower limit of detection with this technique is 0.05 M. Measured spectra revealed trends with respect to polysulfide order and concentration, consistent with theoretical predictions, which were used to develop a set of equations relating the order and concentration of lithium polysulfides in a sample to the position and area of a characteristic infrared absorption band. The diagnostic routine can measure the order and concentration to within 5% and 0.1 M, respectively.
