Search results for "Microwave"

Image-Guided Thermal Ablation as an Alternative to Surgery for Papillary Thyroid Microcarcinoma: Preliminary Results of an Italian Experience

2021

PurposeTo report the results of our preliminary experience in treating patients with papillary thyroid microcarcinoma (PTMC) with image-guided thermal ablation, in particular estimating the feasibility, safety and short-term efficacyMaterials and MethodsFrom 2018 patients with cytologically proven PTMC < 10 mm were discussed in a multidisciplinary team and evaluated for feasibility of image-guided thermal ablation. In case of technical feasibility, the three possible alternatives (i.e., image-guided thermal ablation, surgery, and active surveillance) were discussed with patients. Patients who agreed to be treated with image guided thermal ablation underwent radiofrequency (RFA) or la…

Methane line parameters in the HITRAN2012 database

2013

International audience; The compilation of methane molecular line parameters was updated to include new global analyses and measurements for 12CH4, 13CH4 and 12CH3D. Over 70% of the methane parameters in HITRAN2008 were replaced; existing parameters retained were the microwave lines and the Dyad of 13CH4 near 7 μm and ν6 of 13CH3D near 8.7 μm, 12CH3D (7-4076 cm-1), hot bands of 12CH4 (1887-3370 cm-1) and normal sample CH4 (4800-5550 cm-1 and 8000-9200 cm-1). With a minimum intensity at 296 K in units of cm-1/(molecule cm-2) set to 10-37 for the far-IR and 10-29 for the mid- and near-IR, the methane database increased from 290,091 lines in HITRAN2008 to 468,013 lines, and three-fourths of th…

Thermo-Chemical Conversion of Microwave Activated Biomass Mixtures

2018

Thermal Decomposition and Combustion of Microwave Pre-Treated Biomass Pellets

2021

The objective of the study was to investigate a more effective use of commercially available biomass pellets (wheat straw, wood, peat) using microwave pretreatment to improve heat production. Pellets were pretreated using the originally designed microwave torrefaction device. The effects of microwave (mw) pretreatment were quantified, providing measurements of the weight loss and elemental composition of pellets and estimating the effect of mw pretreatment on their porosity, surface area and calorific values at pretreatment temperatures of T = 448–553 K. Obtained results show that the highest structural variations and elemental composition during mw pretreatment were obtained for wheat stra…

Analysis of the electromagnetic radiation generated by a multipactor discharge occurring within a microwave passive component

2010

International audience; Multipactoring is a non-linear phenomenon that appears in highpower microwave equipments operating under vacuum conditions and causes several undesirable effects. In this manuscript, a theoretical and experimental study of the RF spectrum radiated by a multipactor discharge, occurring within a realistic microwave component based on rectangular waveguides, is reported. The electromagnetic coupling of a multipactor current to the fundamental propagative mode of a uniform waveguide has been analyzed in the context of the microwave network theory. The discharge produced under a single-carrier RF voltage regime has been approached as a shunt current source exciting such a…

VUV irradiance measurement of a 2.45 GHz microwave-driven hydrogen discharge

2015

Absolute values of VUV-emission of a 2.45 GHz microwave-driven hydrogen discharge are reported. The measurements were performed with a robust and straightforward method based on a photodiode and optical filters. It was found that the volumetric photon emission rate in the VUV-range (80-250 nm) is $10^{16}$-$10^{17}$ 1/cm$^3$s, which corresponds to approximately 8% dissipation of injected microwave power by VUV photon emission. The volumetric emission of characteristic emission bands was utilized to diagnostics of molecular plasma processes including volumetric rates of ionization, dissociation and excitation to high vibrational levels and metastable states. The estimated reaction rates impl…

Non-destructive technique to detect local buried defects in metal sample by scanning microwave microscopy

2012

International audience; Based on the skin effect, our recent developments using scanning microwave microscopy lead to propose a non-destructive method to detect located buried defect in metal samples like stainless steel. A 3D tomography is possible by taking advantage of microwave measurement, using a vector network analyzer in bandwidth frequencies, and the nanometer resolution positioning capabilities with atomic force microscopy. At each used frequency, an incident electromagnetic wave is sent to the sample and the reflected wave gives information on a specific depth layer in the material. With diagnostic tools of nanotechnologies (SEM. AFM, etc.), different stainless steel samples (fro…

Development of gas sensors by microwave transduction with phthalocyanine film

2012

International audience; This work presents a new transduction mode for gas sensing using a passive microwave circuit at room temperature. The design of the sensor includes a microstrip line where is deposited a thin molecular layer of cobalt phthalocyanine (CoPc). The material is sensitive to ammonia and toluene. Submitted to an electromagnetic incident wave in the microwave range, the sensor response is a reflected wave. In the presence of ammonia, the reflected wave is specific to the species concentration. The sensor response is the reflected wave over the incident wave ratio at each frequency traduced by the reflected coefficient. The study deals with the influence of molecular sensitiv…

Zirconia Based Nanomaterials for Oxygen Sensors – Generation, Characterisation and Optical Properties

2007

Microwave driven hydrothermal synthesis and hydrothermal synthesis were used to obtain ZrO2 nanopowders. Their production with varying phase composition, the characterisation and selected optical properties concerning their potential use as luminescence oxygen sensors are reported. It was found that the powders obtained by the microwave driven hydrothermal method and annealed at 750 0C in air show experiment repeatability within an accuracy of 6 %.

Rapid Microwave Preparation of Thermoelectric TiNiSn and TiCoSb Half-Heusler Compounds

2012

The 18-electron ternary intermetallic systems TiNiSn and TiCoSb are promising for applications as high-temperature thermoelectrics and comprise earth-abundant, and relatively nontoxic elements. Heusler and half-Heusler compounds are usually prepared by conventional solid state methods involving arc-melting and annealing at high temperatures for an extended period of time. Here, we report an energy-saving preparation route using a domestic microwave oven, reducing the reaction time significantly from more than a week to one minute. A microwave susceptor material rapidly heats the elemental starting materials inside an evacuated quartz tube resulting in near single phase compounds. The initia…