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Implications of inherent inhomogeneities in thin carbon fiber-based gas diffusion layers: A comparative modeling study
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Critical minerals mining and Native American sovereignty: Comparing case studies of lithium, copper, antimony, nickel and graphite mining in the United States
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Comparative Reactivity Study of Forsterite and Antigorite in Wet Supercritical CO2 by In Situ Infrared Spectroscopy
The carbonation reactions of forsterite (Mg2SiO4) and antigorite [Mg3Si2O5(OH)4], representatives of olivine and serpentine minerals, in dry and wet supercritical carbon dioxide (scCO2) at conditions relevant to geologic carbon sequestration (35 °C and 100 bar) were studied by in-situ Fourier transform infrared (FT-IR) spectroscopy. Our results confirm that water plays a critical role in the reactions between metal silicate minerals and scCO2. For neat scCO2, no reaction was observed in 24 hr for either mineral. When water was added to the scCO2, a thin water film formed on the minerals’ surfaces, and the reaction rates and extents increased as the water saturation level was raised from 54% to 116% (excess water). For the first time, the presence of bicarbonate, a key reaction intermediate for metal silicate reactions with scCO2, was observed in a heterogeneous system where mineral solids, an adsorbed water film, and bulk scCO2 co-exist. In excess-water experiments, approximately 4% of forsterite and less than 2% of antigorite transformed into hydrated Mg-carbonates. A precipitate similar to nesquehonite (MgCO3•3H2O) was observed for forsterite within 6 hr of reaction time, but no such precipitate was formed from antigorite until after water was removed from the scCO2 following a 24-hr reaction period. The reduced reactivity and carbonate-precipitation behavior of antigorite was attributed to slower, incongruent dissolution of the mineral and lower concentrations of Mg2+ and HCO3- in the water film. The in situ measurements employed in this work make it possible to quantify metal carbonate precipitates and key reaction intermediates such as bicarbonate for the investigation of carbonation reaction mechanisms relevant to geologic carbon sequestration.
Multi-institutional Pooled Analysis on Adjuvant Chemoradiation in Pancreatic Cancer
Purpose: To determine the impact of chemoradiation therapy (CRT) on overall survival (OS) after resection of pancreatic adenocarcinoma. Methods and Materials: A multicenter retrospective review of 955 consecutive patients who underwent complete resection with macroscopically negative margins (R0-1) for invasive carcinoma (T1-4; N0-1; M0) of the pancreas was performed. Exclusion criteria included metastatic or unresectable disease at surgery, macroscopic residual disease (R2), treatment with intraoperative radiation therapy (IORT), and a histological diagnosis of no ductal carcinoma, or postoperative death (within 60 days of surgery). In all, 623 patients received postoperative radiation therapy (RT), 575 patients received concurrent chemotherapy (CT), and 462 patients received adjuvant CT. Results: Median follow-up was 21.0 months. Median OS after adjuvant CRT was 39.9 versus 24.8 months after no adjuvant CRT (P<.001) and 27.8 months after CT alone (P<.001). Five-year OS was 41.2% versus 24.8% with and without postoperative CRT, respectively. The positive impact of CRT was confirmed by multivariate analysis (hazard ratio [HR] = 0.72; confidence interval [CI], 0.60-0.87; P=.001). Adverse prognostic factors identified by multivariate analysis included the following: R1 resection (HR = 1.17; CI = 1.07-1.28; P<.001), higher pT stage (HR = 1.23; CI = 1.11-1.37; P<.001), positive lymph nodes (HR = 1.27; CI = 1.15-1.41; P<.001), and tumor diameter >20 mm (HR = 1.14; CI = 1.05-1.23; P=.002). Multivariate analysis also showed a better prognosis in patients treated in centers with >10 pancreatic resections per year (HR = 0.87; CI = 0.78-0.97; P=.014) Conclusion: This study represents the largest comparative study on adjuvant therapy in patients after resection of carcinoma of the pancreas. Overall survival was better in patients who received adjuvant CRT.
A comparative experimental study of gas injection in shale plugs by flooding and huff-n-puff processes
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An in silico comparative dosimetric study of postmastectomy locoregional irradiation using intensity-modulated vs 3-dimensional conventional radiotherapy
An in silico dosimetric evaluation of intensity-modulated radiation therapy (IMRT) vs 3-dimensional conventional radiation therapy (3D-CRT) treatment plans in postmastectomy radiation therapy (PMRT) to the chest wall and regional lymphatics was conducted. Twenty-five consecutive patients with breast cancer referred for locoregional PMRT, stages T{sub 2-4} with N{sub 1-3}, were planned to receive 50 Gy in 25 fractions with IMRT. Additionally, a 3D-CRT plan was generated using identical contours for the clinical target volumes (CTV), planning target volumes (PTV), and organs at risk (OAR). Treatment plans were assessed using dose-volume histogram (DVH) parameters of D{sub 98}, D{sub 95}, D{sub 50}, D{sub 2}, and homogeneity index for individual CTVs and PTVs. OARs evaluated were ipsilateral and contralateral lungs, heart, spinal cord, and opposite breast. Most DVH parameters pertaining to CTVs and PTVs significantly favored IMRT. V{sub 20} for ipsilateral and contralateral lungs, D{sub 33} of heart and maximum dose to spinal cord favored IMRT (all p vs 2.0 ± 1.0 Gy, p < 0.001). Thus, except for the mean dose to the opposite breast, the compliance to DVH constraints applied to PTV and OARs were significantly better with IMRT. At a median follow-up of 76 months (7-91), none had locoregional failure or pulmonary or cardiac morbidity. For PMRT, requiring comprehensive irradiation to both chest wall and regional lymphatics, IMRT offers superior dosimetric advantages over 3D-CRT. This was also corroborated by long-term outcomes in these patients treated with IMRT.
Water Oxidation on TiO 2 : A Comparative DFT Study of 1e – , 2e – , and 4e – Processes on Rutile, Anatase, and Brookite
water oxidation in artificial intelligence, with semiconductor materials - comparison between three phases of titania TiO2
Comparative Computational Study of Electronic Excitations of Neutral and Charged Small Oligothiophenes and Their Extrapolations Based on Simple Models
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The effectiveness of TRIS and ammonium buffers in glass dissolution studies: a comparative analysis
Abstract Selecting appropriate buffers is crucial for evaluating the chemical durability of glass under controlled conditions such as in the EPA 1313 test designed to measure elemental release as a function of pH. The efficacy of two alkali-metal free buffers, TRIS (NH 2 C(CH 2 OH) 3 ) and ammonium chloride—ammonia (NH 3 /NH 4 Cl), was investigated during EPA 1313 testing of a simulated Hanford low-activity waste borosilicate glass in the alkaline regime (pH 8.5–10.5) at varying temperatures (RT, 40 °C, and 60 °C). While both buffers maintained the desired pH at room temperature, and up to 40 °C, the effectiveness of TRIS decreased at elevated temperatures, particularly at pH 10.5. Although 11 B NMR showed evidence of TRIS-B complexation, its effect on the rate of elemental release was found to be negligible under the test conditions. With ammonium buffer, the release of alkali cations was slightly elevated when compared to the same conditions with TRIS at early time points.
Comparative numerical study of highly nonlinear flip-through impact experiment
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Comparative optical study of epitaxial InGaAs quantum rods grown with As{sub 2} and As{sub 4} sources
Photoreflectance and photoluminescence (PL) spectroscopies are used to examine the optical properties and electronic structure of InGaAs quantum rods (QRs), embedded within InGaAs quantum well (QW). The nanostructures studied were grown by molecular beam epitaxy using As{sub 2} or As{sub 4} sources. The impact of As source on spectral features associated with interband optical transitions in the QRs and the surrounding QW are demonstrated. A red shift of the QR- and a blue shift of the QW-related optical transitions, along with a significant increase in PL intensity, have been observed if an As{sub 4} source is used. The changes in optical properties are attributed mainly to carrier confinement effects caused by variation of In content contrast between the QR material and the surrounding well.
A comparative wear study on Al-Li and Al-Li/SiC composite
Aluminum-lithium based unreinforced (Al-8090) alloy and Al-8090/SiCp/17 vol.% metal matrix composite produced by extrusion after spray co-deposition. A dry ball-on disk wear test was carried out for both alloy and composite. The tests were performed against an Al{sub 2}O{sub 3} ball, 10 mm in diameter, at room temperature and in laboratory air conditions with a relative humidity of 40-60%. Sliding speed was chosen as 1.0 ms{sup −1} and normal loads of 1.0, 3.0 and 5.0 N were employed at a constant sliding distance of 1000 m. The wear damage on the specimens was evaluated via measurement of wear depth and diameter. Microstructural and wear characterization was carried out via scanning electron microscopy (SEM). The results showed that wear loss of the Al-8090/SiC composite was less than that of the Al-8090 matrix alloy. Plastic deformation observed on the wear surface of the composite and the matrix alloy, and the higher the applied load the greater the plastic deformation. Scanning electron microscopy examinations of wear tracks also reveal that delamination fracture was the dominant wear mechanism during the wear progression. Friction coefficient was maximum at the low applied load in the case of the Al-8090/SiC composite while a gradual increase was observed with applied load for the matrix alloy.
A comparative theoretical study on core-hole excitation spectra of azafullerene and its derivatives
The core-hole excitation spectra—near-edge x-ray absorption spectroscopy (NEXAFS), x-ray emission spectroscopy (XES), and x-ray photoelectron spectroscopy (XPS) shake-up satellites have been simulated at the level of density functional theory for the azafullerene C{sub 59}N and its derivatives (C{sub 59}N){sup +}, C{sub 59}HN, (C{sub 59}N){sub 2}, and C{sub 59}N–C{sub 60}, in which the XPS shake-up satellites were simulated using our developed equivalent core hole Kohn-Sham (ECH-KS) density functional theory approach [B. Gao, Z. Wu, and Y. Luo, J. Chem. Phys. 128, 234704 (2008)] which aims for the study of XPS shake-up satellites of large-scale molecules. Our calculated spectra are generally in good agreement with available experimental results that validates the use of the ECH-KS method in the present work. The nitrogen K-edge NEXAFS, XES, and XPS shake-up satellites spectra in general can be used as fingerprints to distinguish the azafullerene C{sub 59}N and its different derivatives. Meanwhile, different carbon K-edge spectra could also provide detailed information of (local) electronic structures of different molecules. In particular, a peak (at around 284.5 eV) in the carbon K-edge NEXAFS spectrum of the heterodimer C{sub 59}N–C{sub 60} is confirmed to be related to the electron transfer from the C{sub 59}N part to the C{sub 60} part in this charge-transfer complex.