Iterative methods for tomography problems: implementation to a cross-well tomography problem

The velocity distribution between two boreholes is reconstructed by cross-well tomography, which is commonly used in geology. In this paper, iterative methods, Kaczmarz's algorithm, algebraic reconstruction technique (ART), and simultaneous iterative reconstruction technique (SIRT), are implemented to a specific cross-well tomography problem. Convergence to the solution of these methods and their CPU time for the cross-well tomography problem are compared. Furthermore, these three methods for this problem are compared for different tolerance values

Multislice/multidetector-row computed tomography findings of a rare coronary anomaly: the first septal perforator branch originating from the left main coronary artery

Multislice/multidetector-row computed tomography (MDCT) is now widely used for noninvasive assessment of coronary arteries, and it may sometimes reveal coronary anomalies. Detection of such anomalies may be relevant both during follow-up and for planning cardiac or coronary surgical/interventional procedures. These anomalies may be missed unless carefully sought. In this paper, we present the MDCT images of a first septal perforator branch originating from the left main coronary artery, which represents an extremely rare coronary anomaly. To the bestof our knowledge, this is the first case in the literature where MDCT images are presented

Thermodynamic modeling of La2O3-SrO-Mn2O3-Cr2O3 for solid oxide fuel cell applications

The thermodynamic La-Sr-Mn-Cr-O oxide database is obtained as an extension of thermodynamic descriptions of oxide subsystems using the calculation of phase diagrams approach. Concepts of the thermodynamic modeling of solid oxide phases are discussed. Gibbs energy functions of SrCrO4, Sr2.67Cr2O8, Sr2CrO4, and SrCr2O4 are presented, and thermodynamic model parameters of La-Sr-Mn-Chromite perovskite are given. Experimental solid solubilities and nonstoichiometries in La1−x Sr x CrO3−δ and LaMn1−x Cr x O3−δ are reproduced by the model. The presented oxide database can be used for applied computational thermodynamics of traditional lanthanum manganite cathode with Cr-impurities. It represents the fundament for extensions to higher orders, aiming on thermodynamic calculations in noble symmetric solid oxide fuel cell

Thermodynamic Assessment of the La-Fe-O System

The La-Fe and the La-Fe-O systems are assessed using the Calphad approach, and the Gibbs energy functions of ternary oxides are presented. Oxygen and mutual La and Fe solubilities in body-centered cubic (bcc) and face-centered cubic (fcc) structured metallic phases are considered in the modeling. Oxygen nonstoichiometry of perovskite-structured La1±x Fe1±y O3−δ is modeled using the compound energy formalism (CEF), and the model is submitted to a defect chemistry analysis. The contribution to the Gibbs energy of LaFeO3 due to a magnetic order-disorder transition is included in the model description. Lanthanum-doped hexaferrite, LaFe12O19, is modeled as a stoichiometric phase. Δf,elements°H 298K (LaFe12O19)=−5745kJ/mol, °S 298K (LaFe12O19)=683J/mol·K, and Δf,oxides°G (LaFe12O19)=4634−37.071T (J/mol) from 1073 to 1723K are calculated. The liquid phase is modeled using the two-sublattice model for ionic liquids. The calculated La-Fe phase diagram, LaO1.5-FeO x phase diagrams at different oxygen partial pressures, and phase equilibria of the La-Fe-O system at 873, 1073, and 1273K as a function of oxygen partial pressures are presente

Project PROMETHEUS: Design and Construction of a Radio Frequency Quadrupole at TAEK

The PROMETHEUS Project is ongoing for the design and development of a 4-vane radio frequency quadrupole (RFQ) together with its H+ ion source, a low energy beam transport (LEBT) line and diagnostics section. The main goal of the project is to achieve the acceleration of the low energy ions up to 1.5 MeV by an RFQ (352 MHz) shorter than 2 meter. A plasma ion source is being developed to produce a 20 keV, 1 mA H+ beam. Simulation results for ion source, transmission and beam dynamics are presented together with analytical studies performed with newly developed RFQ design code DEMIRCI. Simulation results shows that a beam transmission 99% could be achieved at 1.7 m downstream reaching an energy of 1.5 MeV. As the first phase an Aluminum RFQ prototype, the so-called cold model, will be built for low power RF characterization. In this contribution the status of the project, design considerations, simulation results, the various diagnostics techniques and RFQ manufacturing issues are discussed.Comment: 4 pages, 8 figures, Proceedings of the 2nd International Beam Instrumentation Conference 2013 (IBIC'13), 16-19 Sep 2013, WEPC02, p. 65

Graphene oxide integrated sensor for electrochemical monitoring ofmitomycin C–DNA interaction

WOS: 000302308600025PubMed ID: 22439135We present a graphene oxide (GO) integrated disposable electrochemical sensor for the enhanced detection of nucleic acids and the sensitive monitoring of the surface-confined interactions between the anticancer drug mitomycin C (MC) and DNA. Interfacial interactions between immobilized calf thymus double-stranded (dsDNA) and anticancer drug MC were investigated using differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) techniques. Based on three repetitive voltammetric measurements of 120 mu g mL(-1) DNA immobilized on GO-modified electrodes, the RSD % (n = 3) was calculated as 10.47% and the detection limit (DL) for dsDNA was found to be 9.06 mu g mL(-1). EIS studies revealed that the binding of the drug MC to dsDNA leads to a gradual decrease of its negative charge. As a consequence of this interaction, the negative redox species were allowed to approach the electrode, and thus increase the charge transfer kinetics. On the other hand, DPV studies exploited the decrease of the guanine signal due to drug binding as the basis for specifically probing the biointeraction process between MC and dsDNA.Royal Society through Joint Project Scheme [1212R0168]; Turkish Academy of Sciences (TUBA)Turkish Academy of SciencesThis work was supported by the Royal Society through Joint Project Scheme (Project No. 1212R0168). A.E. acknowledges the Turkish Academy of Sciences (TUBA) as an Associate member for its partial support. Authors would like to thank Dr. M. McMullan for the assistance on the synthesis of graphene oxide

Improved Thermodynamic Descriptions of Carbides in Ni-Based Superalloys

The Ni-based superalloy René 41 has sparked recent interest for applications in next-generation aircraft engines due to its high-temperature strength that is superior to all similar grades. These desirable properties are achieved by careful control of the microstructure evolution during thermomechanical processing, and this is commonly informed by simulations. In particular, the grain boundary carbides M6C and M23C6 play an essential role in controlling the grain size and strength of the final product. Therefore, a solid understanding of the thermodynamic stability and thermokinetic evolution of these carbides is essential. However, thermokinetic simulations using existing thermodynamic databases have been demonstrated to have discrepancies between thermodynamic stabilities and experimental observations. Here, we collected a new experimental time–temperature–precipitation diagram. In conjunction with improved crystallographic descriptions, these experimental results are used to modify a CALPHAD database for M6C and M23C6. The modified database correctly identifies temperature regions with rapid carbide precipitation kinetics. Further, kinetic simulations and strengthening models successfully predict the hardness increase due to γ′ precipitation. The modified database has been applied to Udimet 700, Waspaloy, and Haynes 282, demonstrating improved results. These updates will facilitate more accurate simulations of the microstructure evolution during thermomechanical processing of advanced Ni-based superalloys for aerospace and other applications

Helicobacter pylori Seropositivity and Stool Antigen in Patients With Hyperemesis Gravidarum

The objective of this paper is to investigate whether Helicobacter pylori is an etiologic factor in hyperemesis gravidarum. Thirty one patients with hyperemesis gravidarum and twenty nine pregnant controls without hyperemesis gravidarum were included in this prospective study. All pregnant women were examined both for Helicobacter pylori serum immunoglobulin G antibodies (HpIgG Ab), showing chronic infection, and Helicobacter pylori stool antigens (HpSA), showing active gastrointestinal colonization. Chi-square and Student t tests were used accordingly for statistical analysis. Helicobacter pylori seropositivity was 67.7% in the patients with hyperemesis gravidarum and 79.3% in the control group (χ(2) = 1.02, P = .31). HpSA was detected in 22.6% of patients with hyperemesis gravidarum, whereas 6.9% of patients in the control group. The difference was not statistically significant (χ(2) = 2.89, P = .08). In this study, no relation was found between Helicobacter pylori and hyperemesis gravidarum. The low social status of women in both groups could be one of the reasons for the high prevalence of Hp infection

Peripheral microcirculatory alterations are associated with the severity of acute respiratory distress syndrome in COVID-19 patients admitted to intermediate respiratory and intensive care units

COVID-19; Endothelial dysfunction; MicrocirculationCOVID-19; Disfunción endotelial; MicrocirculaciónCOVID-19; Disfunció endotelial; MicrocirculacióBackground COVID-19 is primarily a respiratory disease; however, there is also evidence that it causes endothelial damage in the microvasculature of several organs. The aim of the present study is to characterize in vivo the microvascular reactivity in peripheral skeletal muscle of severe COVID-19 patients. Methods This is a prospective observational study carried out in Spain, Mexico and Brazil. Healthy subjects and severe COVID-19 patients admitted to the intermediate respiratory (IRCU) and intensive care units (ICU) due to hypoxemia were studied. Local tissue/blood oxygen saturation (StO2) and local hemoglobin concentration (THC) were non-invasively measured on the forearm by near-infrared spectroscopy (NIRS). A vascular occlusion test (VOT), a three-minute induced ischemia, was performed in order to obtain dynamic StO2 parameters: deoxygenation rate (DeO2), reoxygenation rate (ReO2), and hyperemic response (HAUC). In COVID-19 patients, the severity of ARDS was evaluated by the ratio between peripheral arterial oxygen saturation (SpO2) and the fraction of inspired oxygen (FiO2) (SF ratio). Results Healthy controls (32) and COVID-19 patients (73) were studied. Baseline StO2 and THC did not differ between the two groups. Dynamic VOT-derived parameters were significantly impaired in COVID-19 patients showing lower metabolic rate (DeO2) and diminished endothelial reactivity. At enrollment, most COVID-19 patients were receiving invasive mechanical ventilation (MV) (53%) or high-flow nasal cannula support (32%). Patients on MV were also receiving sedative agents (100%) and vasopressors (29%). Baseline StO2 and DeO2 negatively correlated with SF ratio, while ReO2 showed a positive correlation with SF ratio. There were significant differences in baseline StO2 and ReO2 among the different ARDS groups according to SF ratio, but not among different respiratory support therapies. Conclusion Patients with severe COVID-19 show systemic microcirculatory alterations suggestive of endothelial dysfunction, and these alterations are associated with the severity of ARDS. Further evaluation is needed to determine whether these observations have prognostic implications. These results represent interim findings of the ongoing HEMOCOVID-19 trial. Trial registration ClinicalTrials.gov NCT04689477. Retrospectively registered 30 December 2020.The study has received funding from Fundació CELLEX Barcelona, Fundació Mir-Puig, Ajuntament de Barcelona, Agencia Estatal de Investigación (PHOTOMETABO, PID2019-106481RB-C31/10.13039/501100011033), the "Severo Ochoa" Programme for Centers of Excellence in R&D (CEX2019-000910-S), the Obra social “La Caixa” Foundation (LlumMedBcn), Generalitat de Catalunya (CERCA, AGAUR-2017-SGR-1380, RIS3CAT-001-P-001682 CECH), European Commission Horizon 2020 (FEDER, 688303/LUCA, 101016087/VASCOVID, 87114/LASERLAB-EUROPE V). We also acknowledge the collaboration and an instrument loan from Artinis (Netherlands)

New tetracyclic heteroaromatic compounds based on dehydroamino acids : photophysical and electrochemical studies of interaction with DNA

A benzothienoindole (BTIN) and a benzofuroindole (BFIN) were synthesized in high yields, as potential new target DNA compounds, using a metal-assisted intramolecular C-N cyclization, developed by us, of the methyl esters of N-(t-butoxycarbonyl)-b,b-bis(dibenzothien-4-yl or dibenzofuro-4-yl)dehydroalanines. The latter were obtained by a bis-Suzuki coupling of a b,b-dibromodehydroalanine with the corresponding heteroarylboronic acids. The absorption and fluorescence properties of the novel tetracyclic heteroaromatic compounds were studied in different solvents and in the presence of natural double-stranded (ds) salmon sperm DNA. The results in several solvents show that either BTIN or BFIN can be used as fluorescence solvent sensitive probes. Spectroscopic studies of the interaction of both compounds with dsDNA allowed to determine binding constant (Ki) values and binding site sizes (n). Fluorescence quenching experiments using iodide ion allowed the determination of the accessibilities to the quencher, showing that intercalation is the preferred mode of binding of these molecules to DNA. From the results obtained BTIN is the more intercalative compound and has a higher affinity to DNA. The interaction of this more promising compound with DNA was also studied electrochemically, by using differential pulse voltammetry (DPV) in connection with disposable pencil graphite electrode (PGE). These studies are based on the differences in the BTIN and adenine oxidation signals. After the interaction of BTIN with DNA, the oxidation signals of BTIN and adenine strongly decreased. The latter was attributed to the binding of the BTIN to DNA and the former points to a possible damage of the oxidizable groups of the compound after intercalation into DNA. Several concentrations of BTIN were tested and 50 μg/mL was found to be the optimum concentration in order to detect its interaction with DNA. In addition, the detection limit and the reproducibility were determined by using a disposable electrochemical transducer. The results of spectroscopic and electrochemical detection of BTIN interaction with DNA are in good agreement.Academy of Pharmacists and Turkish Pharmacists Association (TEB)Turkish Academy of Sciences - Young Scientist Award Program (KAE/TUBA-GEBIP/2001-2-8)FEDERFundação para a Ciência e a Tecnologia (FCT) - Projecto POCI/QUI/59407/2004. A.S.A. acknowledges a post-doc. grant SFRH/BPD/24548/2005, Bolsa SFRH/BPD/24548/2005.Scientific and Technical Research Council of Turkey (TUBITAK)