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15 pages, 2174 KiB

Open AccessArticle

Electromagnetic Characterization of EAC-1A and JSC-2A Lunar Regolith Simulants

by David Ramos Somolinos, Borja Plaza Gallardo, José Cidrás Estévez, Narek Stepanyan, Aidan Cowley, Alicia Auñón Marugán and David Poyatos Martínez

Materials 2024, 17(15), 3633; https://doi.org/10.3390/ma17153633 - 23 Jul 2024

Cited by 1 | Viewed by 1217

Abstract

The development of devices for the in situ resource utilization (ISRU) of lunar surface powder (regolith) by means of microwaves needs regolith simulants with electromagnetic properties similar to the lunar regolith. This document deals with the measurement of complex permittivity and dielectric loss tangent of the aforementioned simulants at ambient temperature from 400 MHz to 20 GHz, performing measurements using two lunar dust simulants, EAC-1A and JSC-2A, resulting, on the one hand, in permittivity values of

ε^{'} = - 0.0432 f + 4.0397

for the EAC-1A lunar dust simulant and

ε^{'} = - 0.0432 f + 4.0397

for the JSC-2A simulant, and on the other hand, in loss tangent values of

t a n δ_{e} = - 0.0015 f + 0.0659

for the EAC-1A powder and

t a n δ_{e} = - 0.0039 f + 0.1429

for the JSC-2A powder. In addition, further studies are carried out taking into account the humidity of the samples and their densities at room temperature. The obtained results are applicable for comparing the measured values of EAC-1A and JSC-2A between them and with other previously measured simulants and real samples. The measurements are carried out by applying two different nonresonant techniques: Open-Ended Coaxial Probe (OECP) and transmission line. For this purpose, the DAK and EpsiMu commercial kits are used, respectively. Full article

(This article belongs to the Section Advanced Materials Characterization)

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10 pages, 11481 KiB

Open AccessArticle

Endoscopic Pilonidal Sinus Treatment: Preliminary Results, Learning Curve and Comparison with Standard Open Approach

by Giovanni Parente, Francesca Ruspi, Eduje Thomas, Marco Di Mitri, Sara Maria Cravano, Simone D’Antonio, Tommaso Gargano and Mario Lima

Children 2023, 10(6), 1063; https://doi.org/10.3390/children10061063 - 15 Jun 2023

Cited by 3 | Viewed by 5991

Abstract

Background: Pilonidal sinus (PNS) is a common disease which can lead to complications including infection and abscess formation. Different surgical approaches have been suggested, based on primary or secondary wound closure intention healing or endoscopic treatment (EPSiT). The aim of this study is to verify the superior outcomes of EPSiT, especially in comparison with the traditional open approach, and discuss the operators’ learning curve. Methods: A retrospective study was conducted identifying all the patients who underwent surgical treatment for PNS with EPSiT technique between 2019 and 2022 and with open technique between 2002 and 2022. We divided patients in two groups: open procedure (group 1) and EPSiT (group 2). We considered a p value < 0.05 as statistically significant. Results: The mean operative time was 58.6 ± 23.7 min for group 1 and 42.8 ± 17.4 min for group 2 (p < 0.01). The mean hospital stay was 2.6 ± 1.7 days for group 1 patients and of 0.8 ± 0.4 days for group 2 (p < 0.01). Complete healing was obtained in 18.7 ± 5.6 days for group 1 and 38.3 ± 23.5 days for group 2 (p < 0.01). Recurrences were of 23.4% for group 1 and 5.4% for group 2 (p = 0.03). Conclusions: EPSiT is a minimally invasive and effective approach for the treatment of pilonidal cyst that can be safely performed in pediatric patients with promising results concerning aesthetic outcome and pain control, and with a rapid and less complicated recovery compared to traditional open procedures. Full article

(This article belongs to the Section Pediatric Surgery)

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17 pages, 813 KiB

Open AccessArticle

Multi-Echo-Based Echo-Planar Spectroscopic Imaging Using a 3T MRI Scanner

by Jon K. Furuyama, Brian L. Burns, Neil E. Wilson and M. Albert Thomas

Materials 2011, 4(10), 1818-1834; https://doi.org/10.3390/ma4101818 - 17 Oct 2011

Cited by 4 | Viewed by 7564

Abstract

The use of spin-echoes has been employed in an Echo-Planar Spectroscopic Imaging (EPSI) sequence to collect multiple phase encoded lines within a single TR in a Multi-Echo-based Echo-Planar Spectroscopic Imaging technique (MEEPSI). Despite the T₂ dependence on the amplitude of the spin-echoes, the Full Width at Half Maximum (FWHM) of the derived multi-echo Point Spread Function (PSF) is shown to decrease, indicating an improved overall spatial resolution without requiring any additional scan time. The improved spatial resolution is demonstrated in the one-dimensional (1D) spatial profiles of the N-Acetyl Aspartate (NAA) singlet along the phase encode dimension in a gray matter phantom. Although the improved spatial resolution comes at the expense of spectral resolution, it is shown in vivo that peak broadening due to T₂^*decay is more significant than the loss of resolution from using spin-echoes and therefore does not affect the ability to quantify metabolites using the LCModel fitting algorithm. Full article

(This article belongs to the Special Issue High Field Magnetic Resonance Methods and Materials)

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