Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 15 de 15
Filter
1.
Materials (Basel) ; 16(9)2023 May 07.
Article in English | MEDLINE | ID: mdl-37176468

ABSTRACT

In line with global environmental regulations, the demand for eco-friendly and highly efficient aircraft propulsion systems is increasing. The combination of axial flux motors and superconductors could be a key technology used to address these needs. In this paper, an axial flux high temperature superconducting (HTS) motor for aircraft propulsion was designed and its characteristics were analyzed. A 2G HTS wire with high magnetic flux characteristic was used for the field winding of the 120 kW axial flux HTS motor, and the rotational speed and rated voltage of the motor were 2000 rpm and 220 V, respectively. The axial flux HTS motor implements a revolving armature type for solid cooling of the HTS field coil. The electromagnetic and thermal features of the motor were analyzed and designed utilizing a 3D finite element method program. The HTS coil was maintained at the target temperature by effectively designing the current lead and cooling system to minimize heat loss. These results can be effectively used in the design of propulsion systems for large commercial aircraft in the future as well as for the design of small aircraft with less than 4 seats.

2.
J Am Chem Soc ; 144(21): 9217-9221, 2022 Jun 01.
Article in English | MEDLINE | ID: mdl-35588478

ABSTRACT

The ternary neptunium(V) (Np(V)) hydroxides Na0.5[NpO2(OH)1.5]·0.5H2O (I) and Na[NpO2(OH)2] (II) were synthesized in aqueous NaOH solutions at T = 80 °C, and their crystal structures were determined to be monoclinic, P21, Z = 2, a = 5.9859(2), b = 10.1932(3), c = 12.1524(4) Å, ß = 98.864(1)°, V = 732.63(4) Å3 for (I) and orthorhombic, P212121, Z = 4, a = 5.856(7), b = 7.621(9), c = 8.174(9) Å, V = 364.8(7) Å3 for (II). By combining the detailed structural information with results from systematic solubility investigations, a comprehensive chemical and thermodynamic model of the Np(V) behavior in NaCl-NaOH solutions was evaluated. The results reveal a great stability of the ternary Na-Np(V)-OH solid phases that significantly enhances the predominance field of the entire Np(V) redox state to high alkalinity.

3.
Anal Chim Acta ; 1202: 339636, 2022 Apr 15.
Article in English | MEDLINE | ID: mdl-35341521

ABSTRACT

The recently emerged actinide (An) M4,5-edge high-energy resolution X-ray absorption near-edge structure (HR-XANES) technique has proven to be very powerful for oxidation state studies of actinides. In this work, for the first time, Np M5-edge HR-XANES was applied to study Np sorption on illite. By improving the experimental conditions, notably by operation of the spectrometer under He atmosphere, it was possible to measure Np M5-edge HR-XANES spectra of a sample with ≈ 1 µg Np/g illite (1 ppm). This is 30-2000 times lower than Np loadings on mineral surfaces usually investigated by X-ray absorption spectroscopy. A newly designed cryogenic configuration enabled sample temperatures of 141.2 ± 1.5 K and successfully prevented beam-induced changes of the Np oxidation state. The described approach paves the way for the examination of coupled redox/solid-liquid interface reactions of actinide ions via An M4,5-edge HR-XANES spectroscopy at low metal ion concentrations, which are of specific relevance for contaminated sites and nuclear waste disposal studies.


Subject(s)
X-Ray Absorption Spectroscopy , Clay , Oxidation-Reduction , Temperature , X-Ray Absorption Spectroscopy/methods , X-Rays
4.
Clin Imaging ; 83: 172-176, 2022 Mar.
Article in English | MEDLINE | ID: mdl-35092925

ABSTRACT

OBJECTIVES: To describe national practice trends in bone radiofrequency ablation (RFA) and cryoablation for osseous lesions by physician specialty and site-of-service from 2015 to 2018. MATERIALS AND METHODS: This study used data from the US Centers for Medicare and Medicaid Services public use files for 2015-2018. Current Procedural Terminology (CPT) codes for bone RFA (20982) and cryoablation (20983) were analyzed. Based on the specialty code, the specialty was sorted into five categories: radiology (diagnostic and interventional), orthopedic surgery, neurosurgery, pain management (pain management, anesthesiology, physical medicine and rehabilitation, and interventional pain management), and all others. Annual volume of billed services was additionally evaluated by site of service and provider specialty. RESULTS: Aggregate claims dramatically increased from 2015 to 2018. The enrollment adjusted overall growth averaged 45.2.% year-over-year, strongly driven by growth in RFA. Annual market share for radiology decreased slightly from 80.6% to 73.3% with neurosurgery making the largest gain, increasing from 4.7% to 11.3% from 2015 to 2018. Clinical site-of-service analysis demonstrated that outpatient is the main site-of-service for ablation (62.7% cumulatively from 2015 to 2018). Growth rates of outpatient and inpatient services are about the same over this time. CONCLUSIONS: There has been significant growth in osseous ablation between 2015 and 2018, with the growth dominated by Radiologists, although the overall growth rate and the market share of radiology are declining as the growth is outstripped by neurosurgery and orthopedics. Further consideration of these trends will be important for interventional radiologists to assure their involvement and expertise in ablation procedures.


Subject(s)
Neoplasms , Radiology , Aged , Humans , Insurance Claim Review , Medicare , Practice Patterns, Physicians' , Radiologists , United States/epidemiology
5.
Korean J Intern Med ; 37(2): 304-312, 2022 Mar.
Article in English | MEDLINE | ID: mdl-34905815

ABSTRACT

BACKGROUND/AIMS: Helicobacter pylori infection is presumably associated with iron deficiency and iron deficiency anemia (IDA). This study aimed to evaluate the relationship between H. pylori infection and the decline in iron stores in non-elderly adults during their health check-ups. METHODS: We identified a total of 1,069 subjects who were tested for iron, ferritin, and total iron-binding capacity during their health check-ups, from January 2016 to May 2017. Of these, subjects who underwent endoscopy via rapid urease test and those aged 65 years or below were finally enrolled. RESULTS: Overall, 281 subjects were enrolled, and 187 patients (66.5%) tested positive for H. pylori. The mean age was 36.1 years (range, 22 to 65), and 176 subjects (62.6%) were male. The mean levels of hemoglobin (14.1 ± 1.7 g/dL vs. 14.6 ± 1.4 g/dL, p = 0.019) and ferritin (121.7 ± 106.9 ng/mL vs. 151.8 ± 107.8 ng/mL, p = 0.027) in the H. pylori-positive group were significantly lower than those in the H. pylori-negative group. Iron deficiency (ferritin < 30 ng/mL) was more common in patients with H. pylori infection (p = 0.002). There was no significant difference in anemia (hemoglobin < 13 g/dL in men, < 12 g/dL in women) or IDA (anemia, ferritin < 10 ng/mL, and transferrin saturation < 16%) with H. pylori. Logistic regression analysis demonstrated that female sex (odds ratio, 197.559; 95% confidence interval, 26.461 to 1,475.015) and H. pylori infection (odds ratio, 3.033; 95% confidence interval, 1.216 to 7.567) were factors associated with iron deficiency. CONCLUSION: H. pylori infection is associated with iron deficiency, suggesting a decline in iron stores among infected non-elderly adults.


Subject(s)
Anemia, Iron-Deficiency , Anemia , Helicobacter Infections , Helicobacter pylori , Iron Deficiencies , Adult , Anemia/complications , Anemia, Iron-Deficiency/diagnosis , Anemia, Iron-Deficiency/epidemiology , Female , Ferritins , Helicobacter Infections/complications , Helicobacter Infections/diagnosis , Helicobacter Infections/epidemiology , Hemoglobins/analysis , Hemoglobins/metabolism , Humans , Iron , Male , Middle Aged
6.
Nanomaterials (Basel) ; 11(11)2021 Nov 09.
Article in English | MEDLINE | ID: mdl-34835768

ABSTRACT

A cadmium selenide/zinc sulfide (CdSe/ZnS) quantum dot (QD)-based multi-level memory device with the structure [ITO/PEDOT:PSS/QDs/ZnO/Al:Al2O3/QDs/Al] was fabricated via a spin-coating method used to deposit thin films. Two layers of QD thin films present in the device act as charge storage layers to form three distinct states. Zinc oxide (ZnO) and aluminum oxide (Al2O3) were added to prevent leakage. ZnO NPs provide orthogonality between the two QD layers, and a poly(3,4-ethylenedioxythio-phene): poly(styrenesulfonate) (PEDOT:PSS) thin film was formed for effective hole injection from the electrodes. The core/shell structure of the QDs provides the quantum well, which causes the trapping of injected charges. The resistance changes according to the charging and discharging of the QDs' trap site and, as a result, the current through the device also changes. There are two quantum wells, two current changes, and three stable states. The role of each thin film was confirmed through I-V curve analysis and the fabrication conditions of each thin film were optimized. The synthesized QDs and ZnO nanoparticles were evaluated via X-ray diffraction, transmission electron microscopy, and absorbance and photoluminescence spectroscopy. The measured write voltages of the fabricated device were at 1.8 and 2.4 V, and the erase voltages were -4.05 and -4.6 V. The on/off ratio at 0.5 V was 2.2 × 103. The proposed memory device showed retention characteristics of ≥100 h and maintained the initial write/erase voltage even after 200 iterative operations.

7.
Materials (Basel) ; 14(5)2021 Mar 05.
Article in English | MEDLINE | ID: mdl-33807877

ABSTRACT

In this study, the Fe-8Cr-3V-2Mo-2W tool steel powder was deposited on the SCM420 substrate through the directed energy deposition (DED) process. This study focuses on the mechanical properties of the deposited Fe-8Cr-3V-2Mo-2W and the effect of heat treatment on it. The changes in the microstructural characteristics of the deposited region due to heat treatment after deposition were observed. The influence of heat treatment on the mechanical properties was then analyzed accordingly and hence, the hardness, wear, impact and tensile tests were conducted on the deposited material. These properties were compared with those of the commercial tool steel powder M2-deposited material and the carburized specimen. In the deposited Fe-8Cr-3V-2Mo-2W layer, an increased martensite phase fraction was obtained through post-heat treatment and the amount of precipitated carbides was also increased. This increased the hardness from 48 to 62 HRc after heat treatment and the wear resistance was significantly improved as well. The amount of impact energy absorbed decreased from 11 J before heat treatment to 6 J after heat treatment, but the tensile strength significantly increased from 607 to 922 MPa. When compared with the M2-deposited surface, the Fe-8Cr-3V-2Mo-2W deposits had 3% lower surface hardness and 76% lower fracture toughness but exhibited 56% higher tensile strength. When compared with the carburized SCM420, the Fe-8Cr-3V-2Mo-2W deposits exhibited 3% higher surface hardness and wear resistance, 90% lower fracture toughness and 5% higher tensile strength. This study shows that surface hardening through DED can exhibit similar or superior mechanical properties when compared to carburizing.

9.
Eye (Lond) ; 34(9): 1504-1511, 2020 09.
Article in English | MEDLINE | ID: mdl-32350451

ABSTRACT

BACKGROUND/OBJECTIVES: Patients with ophthalmic emergencies often present to emergency rooms. Emergency medicine (EM) physicians should feel comfortable encountering these conditions. We assessed EM physicians' comfort working up, diagnosing, and managing ophthalmic emergencies. SUBJECTS/METHODS: 329 EM physicians participated in this cross-sectional multicentre survey. Questions inquired about the amount, type, and self-perceived adequacy of ophthalmic training. Likert scales were used to assess confidence and comfort working up, diagnosing, and managing ophthalmic emergencies. RESULTS: Participants recall receiving a median of 5 and 10 h of ophthalmic training in medical school and residency, respectively. Few feel this prepared them for residency (16.5%) or practice (52.0%). Only 50.6% feel confident with their ophthalmic exam. Most (75.0%) feel confident in their ability to identify an ophthalmic emergency, but 58.8% feel well prepared to work them up. Responders feel more comfortable diagnosing acute retrobulbar hematoma (72.5%), retinal detachment (69.8%), and acute angle closure glaucoma (78.0%) than central retinal artery occlusion (28.9%) or giant cell arteritis (53.2%). Only 60.2% feel comfortable determining if canthotomy and cantholysis is necessary in the setting of acute retrobulbar hematoma, and 40.3% feel comfortable performing the procedure. There was a trend towards attending physicians and providers in urban and academic settings feeling more comfortable diagnosing and managing ophthalmic emergencies compared to trainees, non-urban, and non-academic physicians. CONCLUSIONS: Many participants do not feel comfortable using ophthalmic equipment, performing an eye exam, making vision or potentially life-saving diagnoses, or performing vision-saving procedures, suggesting the need to increase ophthalmic training in EM curricula.


Subject(s)
Emergency Medicine , Internship and Residency , Physicians , Clinical Competence , Cross-Sectional Studies , Emergencies , Emergency Medicine/education , Humans , United States
10.
Sensors (Basel) ; 18(8)2018 Aug 06.
Article in English | MEDLINE | ID: mdl-30082620

ABSTRACT

A tunable Fabry-Perot interferometer (TFPI)-type wavelength filter designed for the long-wavelength infrared (LWIR) region is fabricated using micro electro mechanical systems (MEMS) technology and the novel polydimethylsiloxane (PDMS) micro patterning technique. The structure of the proposed infrared sensor consists of a Fabry-Perot interferometer (FPI)-based optical filter and infrared (IR) detector. An amorphous Si-based thermal IR detector is located under the FPI-based optical filter to detect the IR-rays filtered by the FPI. The filtered IR wavelength is selected according to the air etalon gap between reflectors, which is defined by the thickness of the patterned PDMS. The 8 µm-thick PDMS pattern is fabricated on a 3 nm-thick Al layer used as a reflector. The air etalon gap is changed using the electromagnetic force between the permanent magnet and solenoid. The measured PDMS gap height is about 2 µm, ranging from 8 µm to 6 µm, with driving current varying from 0 mA to 600 mA, resulting in a tunable wavelength range of 4 µm. The 3-dB bandwidth (full width at half maximum, FWHM) of the proposed filter is 1.5 nm, while the Free Spectral Range (FSR) is 8 µm. Experimental results show that the proposed TFPI can detect a specific wavelength at the long LWIR region.

11.
J Environ Radioact ; 182: 63-69, 2018 Feb.
Article in English | MEDLINE | ID: mdl-29195123

ABSTRACT

Uranium sorption on minerals and related solids depends to a large degree on its aqueous speciation. The present work attempts to understand the U(VI) sorption behavior on silica under environmentally relevant conditions, i.e. at neutral to weakly alkaline pH and in the presence of dissolved calcium and carbonate. Under these conditions, Ca(UO2)(CO3)32- and Ca2(UO2)(CO3)3(aq) complexes emerge as the dominant aqueous U(VI) species. The U(VI) sorption affinity was measured as a function of contact time, solution pH, and humic acid. The U(VI) sorption decreased with increase of pH and was not affected by the addition of 50 mg/L humic acid. On the other hand, nitric acid was more effective than EDTA and carbonate at desorbing U(VI). Generally, the U(VI) sorbed on silica at neutral pH was less readily desorbed than that sorbed at higher pH values. Therefore, the U(VI) complex favorably sorbed on silica at the neutral pH is more strongly bound to the silica surface than that sorbed at higher pH values. Time-resolved laser fluorescence spectroscopy confirmed the results of the batch sorption experiments and revealed the presence of two surface U(VI) complexes with fluorescence lifetimes 251 ± 8 µs and 807 ± 24 µs.


Subject(s)
Models, Chemical , Silicon Dioxide/chemistry , Uranium/analysis , Adsorption , Calcium/chemistry , Carbonates/chemistry , Humic Substances , Hydrogen-Ion Concentration
12.
World J Gastroenterol ; 23(3): 505-515, 2017 Jan 21.
Article in English | MEDLINE | ID: mdl-28210087

ABSTRACT

AIM: To evaluate the prognostic value of the neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) in patients with colorectal cancer (CRC). METHODS: Between April 1996 and December 2010, medical records from a total of 1868 patients with CRC were retrospectively reviewed. The values of simple inflammatory markers including NLR and PLR in predicting the long-term outcomes of these patients were evaluated using Kaplan-Meier curves and Cox regression models. RESULTS: The median follow-up duration was 46 mo (interquartile range, 22-73). The estimation of NLR and PLR was based on the time of diagnosis. In multivariate Cox regression analysis, high NLR (≥ 3.0) and high PLR (≥ 160) were independent risk factors predicting poor long-term outcomes in patients with stage III and IV CRC. However, high NLR and high PLR were not prognostic factors in patients with stage I and II CRC. CONCLUSION: In this study, we identified that high NLR (≥ 3.0) and high PLR (≥ 160) are useful prognostic factors to predict long-term outcomes in patients with stage III and IV CRC.


Subject(s)
Blood Platelets , Colorectal Neoplasms/blood , Colorectal Neoplasms/mortality , Lymphocytes , Neutrophils , Adult , Aged , Aged, 80 and over , Biomarkers, Tumor/blood , Colorectal Neoplasms/pathology , Feasibility Studies , Female , Humans , Kaplan-Meier Estimate , Lymphocyte Count , Male , Middle Aged , Neoplasm Staging , Platelet Count , Predictive Value of Tests , Prognosis , Proportional Hazards Models , Retrospective Studies , Survival Rate
13.
Medicine (Baltimore) ; 95(47): e5424, 2016 Nov.
Article in English | MEDLINE | ID: mdl-27893682

ABSTRACT

INTRODUCTION: Halomonas hamiltonii is a Gram-negative, halophilic, motile, and nonspore-forming rod bacterium. Although most Halomonas sp. are commonly found in saline environments, it has rarely been implicated as a cause of human infection. Herein, the authors present a case report of continuous ambulatory peritoneal dialysis (CAPD)-related peritonitis attributed to H hamiltonii. CASE PRESENTATION: An 82-year-old male patient who had been receiving CAPD therapy presented to an emergency department with complaints of abdominal pain and cloudy dialysate that had persisted for 2 days. The peritoneal dialysate was compatible with CAPD peritonitis, with white blood cell count of peritoneal effluent of 810/mm and neutrophils predominated (60%). Two days after culture on blood agar medium, nonhemolytic pink mucoid colonies showed, with cells showing Gram-negative, nonspore-forming rods with a few longer and larger bacilli than usual were found. We also performed biochemical tests and found negative responses in K/K on the triple sugar iron test and H2S and equivocal (very weak) response in the motility test, but positive responses to catalase, oxidase, and urease tests. The partial sequence of the 16S rRNA gene of a bacterium detected by peritoneal fluid culture was utilized for a Basic Local Alignment Search Tool search, which revealed that the organism was H hamiltonii. Intraperitoneal antibiotics were administered for 21 days, and the patient was discharged without clinical problems. CONCLUSION: We present here the first case report of CAPD-related peritonitis caused by H hamiltonii, which was identified using molecular biological techniques. Although guidelines do not exist for the treatment of infections caused by this organism, conventional treatment for Gram-negative organisms could be effective.


Subject(s)
Gram-Negative Bacterial Infections/microbiology , Halomonas/isolation & purification , Peritoneal Dialysis, Continuous Ambulatory/adverse effects , Peritonitis/microbiology , Aged, 80 and over , Anti-Bacterial Agents/therapeutic use , Gram-Negative Bacterial Infections/drug therapy , Humans , Male , Peritonitis/drug therapy
14.
Genes Dev ; 29(13): 1362-76, 2015 Jul 01.
Article in English | MEDLINE | ID: mdl-26159996

ABSTRACT

Epigenetic mechanisms, including histone post-translational modifications, control longevity in diverse organisms. Relatedly, loss of proper transcriptional regulation on a global scale is an emerging phenomenon of shortened life span, but the specific mechanisms linking these observations remain to be uncovered. Here, we describe a life span screen in Saccharomyces cerevisiae that is designed to identify amino acid residues of histones that regulate yeast replicative aging. Our results reveal that lack of sustained histone H3K36 methylation is commensurate with increased cryptic transcription in a subset of genes in old cells and with shorter life span. In contrast, deletion of the K36me2/3 demethylase Rph1 increases H3K36me3 within these genes, suppresses cryptic transcript initiation, and extends life span. We show that this aging phenomenon is conserved, as cryptic transcription also increases in old worms. We propose that epigenetic misregulation in aging cells leads to loss of transcriptional precision that is detrimental to life span, and, importantly, this acceleration in aging can be reversed by restoring transcriptional fidelity.


Subject(s)
Epigenesis, Genetic/physiology , Histone Demethylases/genetics , Histone Demethylases/metabolism , Histones/metabolism , Longevity/genetics , Animals , Caenorhabditis elegans/enzymology , Caenorhabditis elegans/genetics , Epigenesis, Genetic/genetics , Gene Deletion , Gene Expression Regulation, Developmental , Methylation , Mutation , Protein Processing, Post-Translational/genetics , Repressor Proteins/genetics , Saccharomyces cerevisiae/enzymology , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae Proteins/genetics
15.
Dalton Trans ; 42(27): 9862-9, 2013 Jul 21.
Article in English | MEDLINE | ID: mdl-23689422

ABSTRACT

The chemical behavior of ternary Ca-UO2-CO3 complexes was investigated by using time-resolved laser fluorescence spectroscopy (TRLFS) in combination with EDTA complexation at pH 7-9. A novel TRLFS revealed two distinct fluorescence lifetimes of 12.7 ± 0.2 ns and 29.2 ± 0.4 ns for uranyl complexes which were formed increasingly dependent upon the calcium ion concentration, even though nearly indistinguishable fluorescence peak shapes and positions were measured for both Ca-UO2-CO3 complexes. For identifying the stoichiometric number of complexed calcium ions, slope analysis in terms of relative fluorescence intensity versus calcium concentration was employed in a combination with the complexation reaction of CaEDTA(2-) by adding EDTA. The formation of CaUO2(CO3)3(2-) and Ca2UO2(CO3)3(aq) was identified under given conditions and their formation constants were determined at I = 0.1 M Na/HClO4 medium, and extrapolated to infinitely dilute solution using specific ion interaction theory (SIT). As a result, the formation constants for CaUO2(CO3)3(2-) and Ca2UO2(CO3)3(aq) were found to be log ß113(0) = 27.27 ± 0.14 and log ß213(0) = 29.81 ± 0.19, respectively, providing that the ternary Ca-UO2-CO3 complexes were predominant uranium(vi) species at neutral to weakly alkaline pH in the presence of Ca(2+) and CO3(2-) ions.

SELECTION OF CITATIONS
SEARCH DETAIL
...