This work presents an improved approach to characterize human head tissue by the microwave imaging technique. Microwave imaging is a non-invasive and non-ionizing imaging technique that employs low-power microwave signals. The detector is a highly directional Antipodal Vivaldi Antenna with a trapezoidal parasitic patch at the aperture and operates at a resonance frequency of 3.2 GHz. The interaction of the electromagnetic wave with human head tissue is analyzed by modelling a heterogeneous head mimicking phantom whose dielectric properties are like human head tissue. The tumor tissue is detected by analyzing reflected signals from an antenna. Tumor tissue produces strong reflections compared to surrounding healthy tissues because of changes in permittivity and conductivity. The size of the tumor is measured by the Resonant Frequency Shifting technique and the depth of the tumor is precisely detected by the Ground Penetrating Radar algorithm.
The vibration of the human middle ear shows sharp variations in the amplitude and phase over the audible frequency range. Measurements often differ between subjects, and it is difficult to determine the average response of the human middle ear. However, such an average response curve is of great value in detecting pathological ears. Simply averaging the amplitude and phase for each frequency results in a “washed-out” view due to differences in the locations of the maxima and minima of the curves. Therefore, a method is required to consider each individual curve's shape in the average.This paper discusses a novel method based on frequency-response transfer functions. Each of the individual measurements is fitted with a rational polynomial. The average frequency response is determined by a weighted averaging of the individual curves' numerator and denominator polynomial coefficients. Such an average preserves the shape of the individual curves. The method is applied to vibrational data of the human stapes. As expected from the literature, two resonance frequencies at 1.14 ± 0.13 kHz and 3.61 ± 0.43 kHz were found. A comparison with other methods is made to discuss the method's advantages and disadvantages.
Nickel-based catalysts are currently the subject of intensive study in the search for novel electrode materials for non-enzymatic glucose sensing. Their strong activity towards glucose electrooxidation and intrinsic resistance to chloride poisoning makes these catalysts ideal candidates for the development of affordable and stable glucose sensors. In this review, the mechanism of glucose electrooxidation at Ni electrodes is described, clarifying the effect of the different phases of Ni on their catalytic activity. Moreover, a brief background on chloride poisoning is provided, supplemented by computational studies. Furthermore, this article details the most intriguing compounds of Ni (selenides, sulfides, nitrates) and the analytical performance of the respective sensors. Additional focus points of this work are multimetallic nanosystems where Ni is a component, and the growing field of conductive metal organic frameworks with Ni centers. This review will be beneficial for researchers who aim at delving deeper into the potential of Ni-based materials for glucose sensing.
Uniform and Monodisperse AgNPs were synthesized via a simple chemical reduction approach the synthesized AgNPs' characterizations were as follows: UV–Vis analysis displayed Surface plasmon resonance (SPR) of AgNPs peaked around 425 nm. AgNPs were shown to have a crystalline structure with a face-centered cubic (FCC) lattice using X-ray diffraction (XRD) investigation. Transmission electron microscopy (TEM) images illustrated a spherical in shape and well dispersant AgNPs, having a 12 nm average size. The AgNPs' stability was confirmed by dynamic light scattering (DLS) data with the coincidence of hydrodynamic diameter to the nominal particle size obtained from TEM. Interestingly, the synthesized AgNPs demonstrated a dose-dependent reduction of thyroid carcinoma growth, the Papillary (MDA-T22) and the Follicular (FTC-133) cells with determined IC50 values of 71.35 and 52.79 μg/ml, respectively. Meanwhile, against normal cells (WRL-68) the AgNPs had no cytotoxic effect at low concentrations and minimal cytotoxicity at higher of 200–400 μg/ml with a significantly increased IC50 value reached to 218.4 μg ml−1. The induced apoptosis of AgNPs treated cancer cells was determined by a High-content screening (HCS) assay. Moreover, the apoptotic morphological changes were explored and the mechanism of affected living cells to apoptosis showed an increase in cell membrane permeability, cytochrome c level, and nuclear intensity in dose-dependent with a significant deferent at higher concentrations (100 and 200 μg mL−1) (p < 0.0001). Conversely, a noticeable decrease in cell viable count and mitochondrial membrane permeability was observed with AgNPs treatment compared with control. Our findings indicate the potential suitability of these nanoparticles for biological and clinical applications.
PEM (Positron Emission Mammography) imaging is a molecular imaging technique for early diagnosis and staging of breast cancer. So, it is very important to check the performance of the PAM device in order to improve the image quality. The aim of this work was to investigate the effects of Time Of Flight (TOF) and Depth Of Interaction (DOI) corrections in the PEM system's performance. For this purpose, the commercially available clinical PEM scanner (PEM Flex Solo II, Naviscan) was simulated using GATE software. This system consists of two non-rotating detector heads that are positioned in an opposing fashion on each side of the body part. Each detector head contains 12 sensitive PMTs with a 6 × 2 array. Also, each PMT is coupled by a light guide to 169 crystals with a 13 × 13 array of 2 mm × 2 mm × 13 mm LYSO crystals. The sensitivity parameter and the scattering fraction of the system were investigated according to the NEMA NU4-2008 standard's manual. Then to assessment the effect of TOF, the coincidence time resolution was changed from 900ps to 100ps. The maximum of NECR curve increases by 42.3% for considering the TOF in the simulation. Also, the Phoswich detector with BGO and LYSO crystals was used to investigate the effect of DOI. The results also show that in Phoswich detector with LYSO crystal with a thickness of 5 mm and BGO crystal with a thickness of 9 mm, the maximum NECR curve increases by 54%. The spatial resolution of the system improves from 2.4 mm to 1 mm by considering TOF and DOI. According to these results, considering the TOF and DOI have a significant role in improving the performance of the PEM system.
