763 research outputs found
Quantum enhanced X-ray detection
We present the first experimental demonstration of quantum-enhanced detection
at x-ray wavelengths. We show that x-ray pairs that are generated by
spontaneous down-conversion can be used for the generation of heralded x-ray
photons and measure directly the sub-Poissonian statistics of the single
photons by using photon number resolving detectors. We utilize the properties
of the strong time-energy correlations of the down converted photons to
demonstrate the ability to improve the visibility and the signal-to-noise ratio
of an image with a small number of photons in an environment with a noise level
that is higher than the signal by many orders of magnitude. In our work we
demonstrate a new protocol for the measurement of quantum effects with x-rays
using advantages such as background free measurements that the x-ray regime
offers for experiments aiming at testing fundamental concepts in quantum
optics.Comment: 12 page
Surface Engineering Strategy Using Urea To Improve the Rate Performance of Na2Ti3O7 in NaâIon Batteries
Na2Ti3O7 (NTO) is considered a promising anode material for Naâion batteries due to its layered structure with an open framework and low and safe average operating voltage of 0.3â
V vs. Na+/Na. However, its poor electronic conductivity needs to be addressed to make this material attractive for practical applications among other anode choices. Here, we report a safe, controllable and affordable method using urea that significantly improves the rate performance of NTO by producing surface defects such as oxygen vacancies and hydroxyl groups, and the secondary phase Na2Ti6O13. The enhanced electrochemical performance agrees with the higher Na+ ion diffusion coefficient, higher charge carrier density and reduced bandgap observed in these samples, without the need of nanosizing and/or complex synthetic strategies. A comprehensive study using a combination of diffraction, microscopic, spectroscopic and electrochemical techniques supported by computational studies based on DFT calculations, was carried out to understand the effects of this treatment on the surface, chemistry and electronic and charge storage properties of NTO. This study underscores the benefits of using urea as a strategy for enhancing the charge storage properties of NTO and thus, unfolding the potential of this material in practical energy storage applications
Heat-Up Colloidal Synthesis of Shape-Controlled Cu-Se-S NanostructuresâRole of Precursor and Surfactant Reactivity and Performance in N2 Electroreduction
Copper selenide-sulfide nanostructures were synthesized using metal-organic chemical routes in the presence of Cu- and Se-precursors as well as S-containing compounds. Our goal was first to examine if the initial Cu/Se 1:1 molar proportion in the starting reagents would always lead to equiatomic composition in the final product, depending on other synthesis parameters which affect the reagents reactivity. Such reaction conditions were the types of precursors, surfactants and other reagents, as well as the synthesis temperature. The use of âhot-injectionâ processes was avoided, focusing on ânon-injectionâ ones; that is, only heat-up protocols were employed, which have the advantage of simple operation and scalability. All reagents were mixed at room temperature followed by further heating to a selected high temperature. It was found that for samples with particles of bigger size and anisotropic shape the CuSe composition was favored, whereas particles with smaller size and spherical shape possessed a Cu2âxSe phase, especially when no sulfur was present. Apart from elemental Se, Al2Se3 was used as an efficient selenium source for the first time for the acquisition of copper selenide nanostructures. The use of dodecanethiol in the presence of trioctylphosphine and elemental Se promoted the incorporation of sulfur in the materials crystal lattice, leading to Cu-Se-S compositions. A variety of techniques were used to characterize the formed nanomaterials such as XRD, TEM, HRTEM, STEM-EDX, AFM and UV-Vis-NIR. Promising results, especially for thin anisotropic nanoplates for use as electrocatalysts in nitrogen reduction reaction (NRR), were obtained
Postextubation pulmonary edema: A case series and review
SummaryWe report a series of patients with postextubation pulmonary edema who had no obvious risk factors for the development of this syndrome.MethodsPatients identified by the pulmonary consultation service at an academic medical center were reviewed.ResultsFourteen cases were collected and analyzed. The average age was 34.5 years; 12 patients were male. The average BMI was 25.5. None had documented previous lung disease. Most operations were scheduled as outpatient procedures, and the type of surgery ranged from an incision and drainage of a bite wound to an open reduction- internal fixation of the radius. None of the patients had upper airway surgery. The length of surgeries ranged from 27 to 335min. Laryngospasm was the most commonly identified obstructing event postextubation. Treatment involved airway support when needed, supplemental oxygen, and diuretics.ConclusionsIt would appear that all patients, especially young men, are at risk for the development of this syndrome and that the pathogenesis remains uncertain in many cases
Genetic Loci of Beta-Aminoisobutyric Acid Are Associated With Aging-Related Mild Cognitive Impairment
We studied the genetic associations of a previously developed Metabolomic Risk Score (MRS) for Mild Cognitive Impairment (MCI) and beta-aminoisobutyric acid metabolite (BAIBA)-the metabolite highlighted by results from a genome-wide association study (GWAS) of the MCI-MRS, and assessed their association with MCI in datasets of diverse race/ethnicities. We first performed a GWAS for the MCI-MRS and BAIBA, in Hispanic/Latino adults (n = 3890) from the Hispanic Community Health Study/Study of Latinos (HCHS/SOL). We identified ten independent genome-wide significant (p value \u3c5 Ă 10-8) variants associated with MCI-MRS or BAIBA. Variants associated with the MCI-MRS are located in the Alanine-Glyoxylate Aminotransferase 2 (AGXT2 gene), which is known to be associated with BAIBA metabolism. Variants associated with BAIBA are located in the AGXT2 gene and in the SLC6A13 gene. Next, we tested the variants\u27 association with MCI in independent datasets of n = 3178 HCHS/SOL older individuals, n = 3775 European Americans, and n = 1032 African Americans from the Atherosclerosis Risk In Communities (ARIC) study. Variants were considered associated with MCI if their p value \u3c0.05 in the meta-analysis of the three datasets and their direction of association was consistent with expectation. Rs16899972 and rs37369 from the AGXT2 region were associated with MCI. Mediation analysis supported the mediation effect of BAIBA between the two genetic variants and MCI (p value = 0.004 for causal mediated effect). In summary, genetic variants in the AGXT2 region are associated with MCI in Hispanic/Latino, African, and European American populations in the USA, and their effect is likely mediated by changes in BAIBA levels
Gender divisions of domestic labour and paid domestic services
This article investigates the relationship between sharing domestic tasks in dual-earner mixed-sex couples and using of paid domestic services. Results from a small-scale survey of the domestic outsourcing practices of employees of a large service-sector organisation in the UK show that in households: full-time working by women and presence of younger children is positively associated with using of domestic services; there is no association between the gender division of traditionally female domestic tasks carried out within the couple and paid services; in contrast, menâs greater involvement in traditionally male and traditionally gender-neutral tasks is positively associating with using paid domestic services. These findings tentatively suggest a new arrangement may be emerging whereby some couples address a heavy workload and desire for a less traditional division of domestic labour by men participating more in close-ended domestic tasks and outsourcing more time-consuming tasks traditionally undertaken by women to paid service providers
Functionalized metallic 2D transition metal dichalcogenide-based solid-state electrolyte for flexible all-solid-state supercapacitors
Highly efficient and durable flexible solid-state supercapacitors (FSSSCs) are emerging as low-cost devices for portable and wearable electronics due to the elimination of leakage of toxic/corrosive liquid electrolytes and their capability to withstand elevated mechanical stresses. Nevertheless, the spread of FSSSCs requires the development of durable and highly conductive solid-state electrolytes, whose electrochemical characteristics must be competitive with those of traditional liquid electrolytes. Here, we propose an innovative composite solid-state electrolyte prepared by incorporating metallic two-dimensional group-5 transition metal dichalcogenides, namely, liquid-phase exfoliated functionalized niobium disulfide (f-NbS2) nanoflakes, into a sulfonated poly(ether ether ketone) (SPEEK) polymeric matrix. The terminal sulfonate groups in f-NbS2 nanoflakes interact with the sulfonic acid groups of SPEEK by forming a robust hydrogen bonding network. Consequently, the composite solid-state electrolyte is mechanically/dimensionally stable even at a degree of sulfonation of SPEEK as high as 70.2%. At this degree of sulfonation, the mechanical strength is 38.3 MPa, and thanks to an efficient proton transport through the Grotthuss mechanism, the proton conductivity is as high as 94.4 mS cmâ1 at room temperature. To elucidate the importance of the interaction between the electrode materials (including active materials and binders) and the solid-state electrolyte, solid-state supercapacitors were produced using SPEEK and poly(vinylidene fluoride) as proton conducting and nonconducting binders, respectively. The use of our solid-state electrolyte in combination with proton-conducting SPEEK binder and carbonaceous electrode materials (mixture of activated carbon, single/few-layer graphene, and carbon black) results in a solid-state supercapacitor with a specific capacitance of 116 F gâ1 at 0.02 A gâ1, optimal rate capability (76 F gâ1 at 10 A gâ1), and electrochemical stability during galvanostatic charge/discharge cycling and folding/bending stresses
Statin Efficacy and Safety for Lipid Modification in Apparently Healthy Male Military Aircrew
Introduction: Military aircrew men represent an elite group of relatively young, fit, and healthy people. The effectiveness of statin treatment in reducing low-density lipoprotein cholesterol (LDL-C) according to the current National Cholesterol Education Program (NCEP) guidelines, its safety, and compliance in this group of people has not yet been determined. Methods: We prospectively evaluated 84 military aircrew men (mean age 43 ĎŽ 7 yr) with LDL-C above the current NCEP guidelines. The patients were divided into two groups according to their coronary risk factors: Group 1, LDL-C goal Ď˝ 160 mg â
dL ĎŞ1 ; Group 2, LDL-C goal Ď˝ 130 mg â
dL ĎŞ1 . All patients received statins in addition to therapeutic lifestyle changes and were followed for a mean of 3 ĎŽ 1 yr according to a simple flow chart. Lipoprotein levels, liver function tests, creatinine phosphokinase, and subjective adverse reactions were checked periodically. Results: LDL-C significantly declined by 32% (p Ď˝ 0.0001) within the first month of treatment and 99% of subjects achieved their LDL-C goal within 114 ĎŽ 35 d from statin therapy initiation. The Framingham estimated 10-yr coronary risk showed a reduction at an average of 12 mo after statin therapy initiation from a baseline value of 6.54% to 3.95% (p Ď 0.003). No subjects were grounded or disqualified from duty, there were no cardiovascular events during follow-up, and compliance to therapy was high [82/84 (98%)]. Discussion: Statin treatment in this highly select, relatively young group of aircrew men significantly and safely lowered LDL-C cholesterol levels
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