Polymer Sensors for the Quantification of Waterborne Uranium

Clandestine activities involving the separation, concentration or manipulation of special nuclear material for the express purpose of developing a weapon of mass destruction is likely to result in the contamination of environmental water sources. The capability to conduct isotopic analyses for waterborne special nuclear material, like uranium, would be a powerful nuclear forensics tool. Despite widespread interest, there currently is no on-line or field-able measurement system available for low-level quantification of uranium in aqueous solutions. A recent development in environmental sensing is a portable, flow cell detector that utilizes extractive scintillating (ES) resin. The ES resin serves the dual purpose of (1) concentrating the radionuclide of interest and (2) serving as a radiation transducer. Currently, such resins are produced by physically absorbing organic extractants and fluors into a polymer matrix. Unfortunately, this approach yields resins with poor stability as the active components leach from the resin over time. This contribution describes our work to increase resin stability by synthesizing ES resin in which the active components are bound covalently within the polymer matrix. The extraction and fluorescence properties of the resin were studied separately before the resin was applied in flow cell detector where detection efficiencies of 40% were achieved

Strukturna i dielektrična svojstva nanostrukturnih prahova BaTiO3 punjenih ionima Eu3+ I pripremljenih sol-gel procesom

Nano-structure BaTiO3 powders doped with Eu3+ ions have been prepared by a sol-gel technique. X-ray diffraction (XRD) results indicate that BaTiO3 gel powders crystallize into tetragonal symmetry on heat treatment at 750 ◦C. Particle sizes as small as 3.5 nm were measured for pure BaTiO3 powders. The XRD data were confirmed by transmission electron microscope. Room-temperature luminescence spectra of BaTiO3:0.5% Eu3+, BaTiO3:1% Eu3+ and BaTiO3:2% Eu3+ powders have been measured. The luminescence spectra of prepared ultrafine powders are dominated by the 5D0 →7F2 transition in Eu3+, suggesting a strong distortion of the Eu3+ sites. The foreign ions are mainly accommodated in Ba2+ tetragonal sites, which are then distorted by the occurrence of different ionic charge of the two cations Ba2+ and Eu3+. The dielectric constant, ε, of BaTiO3, BaTiO3:0.5% Eu3+, BaTiO3:1% Eu3+ and BaTiO3:2% Eu3+ powders at frequency 100 Hz was found to be equal to 1000, 1211, 1455 and 1800, respectively. This high dielectric constant is believed to arise from the increase of the crystallite size, when increasing the concentration of Eu3+ ions. After annealing in argon at 400 ◦C for two hours, at 100 Hz, the dielectric constant of the pure sample was 625 and the AC resistivity also decreased. The room temperature (RT) AC resistivity of the samples depends on the concentration of Eu3+ ions in BaTiO3 powders, and was found to decrease as the concentration of Eu3+ ions increased.Pripremali smo sol-gel metodom nanostrukturne prahove BaTiO3 punjene Eu3+ ionima. Difrakcija X-zračenja (DXZ) pokazuje da se gel prahovi BaTiO3 kristaliziraju u tetragonalnoj simetriji zagrijavanjem na 750 ◦C. Utvrdili smo veličine zrna od samo 3.5 nm u čistom prahu BaTiO3. Podatke od DXZ potvrdili smo prolaznom elektronskom mikroskopijom. Mjerili smo fotoluminescentne spektre prahova BaTiO3:0.5% Eu3+, BaTiO3:1% Eu3+ i BaTiO3:2% Eu3+ na sobnoj temperaturi. U luminescentnim spektrima pripremljenih ultrafinih prahova prevladava prijelaz 5D0 →7F2 u Eu3+, što ukazuje na snažna izobličenja na mjestima Eu3+ iona. Ugrađeni se ioni Eu3+ uglavnom smještaju na tetragonalne položaje Ba2+, a velika razlika ionskih naboja dvaju kationa, Ba2+ i Eu3+, uzrokuje snažne promjene oko tog defekta. Dielektrične konstante, ε, prahova BaTiO3, BaTiO3:0.5% Eu3+, BaTiO3:1% Eu3+ i BaTiO3:2% Eu3+ na frekvenciji 100 Hz prema našim mjerenjima iznose 1000, 1211, 1455 odn. 1800. Smatramo da su tako velike vrijednosti dielektrične konstante posljedica povećanih veličina kristalita za veća punjenja ionima Eu3+. Nakon opuštanja u argonu na 400 ◦C tijekom dva sata, dielektrična konstanta čistog praha bila je 625, a otpornost se također smanjila. Izmjenična otpornost prahova BaTiO3 ovisi o punjenju ionima Eu3+ i nalazi se da se smanjuje kada se poveća sadržaj iona Eu3+

How Supraphysiological Oxygen Levels in Standard Cell Culture Affect Oxygen-Consuming Reactions.

Most mammalian tissue cells experience oxygen partial pressures in vivo equivalent to 1-6% O2 (i.e., physioxia). In standard cell culture, however, headspace O2 levels are usually not actively regulated and under these conditions are ~18%. This drives hyperoxia in cell culture media that can affect a wide variety of cellular activities and may compromise the ability of in vitro models to reproduce in vivo biology. Here, we review and discuss some specific O2-consuming organelles and enzymes, including mitochondria, NADPH oxidases, the transplasma membrane redox system, nitric oxide synthases, xanthine oxidase, and monoamine oxidase with respect to their sensitivities to O2 levels. Many of these produce reactive oxygen and/or nitrogen species (ROS/RNS) as either primary end products or byproducts and are acutely sensitive to O2 levels in the range from 1% to 18%. Interestingly, many of them are also transcriptional targets of hypoxia-inducible factors (HIFs) and chronic cell growth at physioxia versus 18% O2 may alter their expression. Aquaporins, which facilitate hydrogen peroxide diffusion into and out of cells, are also regulated by HIFs, indicating that O2 levels may affect intercellular communication via hydrogen peroxide. The O2 sensitivities of these important activities emphasize the importance of maintaining physioxia in culture.Peer Reviewe

The clinical relevance of oliguria in the critically ill patient : Analysis of a large observational database

Funding Information: Marc Leone reports receiving consulting fees from Amomed and Aguettant; lecture fees from MSD, Pfizer, Octapharma, 3 M, Aspen, Orion; travel support from LFB; and grant support from PHRC IR and his institution. JLV is the Editor-in-Chief of Critical Care. The other authors declare that they have no relevant financial interests. Publisher Copyright: © 2020 The Author(s). Copyright: Copyright 2020 Elsevier B.V., All rights reserved.Background: Urine output is widely used as one of the criteria for the diagnosis and staging of acute renal failure, but few studies have specifically assessed the role of oliguria as a marker of acute renal failure or outcomes in general intensive care unit (ICU) patients. Using a large multinational database, we therefore evaluated the occurrence of oliguria (defined as a urine output 16 years) patients in the ICON audit who had a urine output measurement on the day of admission were included. To investigate the association between oliguria and mortality, we used a multilevel analysis. Results: Of the 8292 patients included, 2050 (24.7%) were oliguric during the first 24 h of admission. Patients with oliguria on admission who had at least one additional 24-h urine output recorded during their ICU stay (n = 1349) were divided into three groups: transient - oliguria resolved within 48 h after the admission day (n = 390 [28.9%]), prolonged - oliguria resolved > 48 h after the admission day (n = 141 [10.5%]), and permanent - oliguria persisting for the whole ICU stay or again present at the end of the ICU stay (n = 818 [60.6%]). ICU and hospital mortality rates were higher in patients with oliguria than in those without, except for patients with transient oliguria who had significantly lower mortality rates than non-oliguric patients. In multilevel analysis, the need for RRT was associated with a significantly higher risk of death (OR = 1.51 [95% CI 1.19-1.91], p = 0.001), but the presence of oliguria on admission was not (OR = 1.14 [95% CI 0.97-1.34], p = 0.103). Conclusions: Oliguria is common in ICU patients and may have a relatively benign nature if only transient. The duration of oliguria and need for RRT are associated with worse outcome.publishersversionPeer reviewe

Verfahren zur Berechnung poroeser, luftgekuehlter Gasturbinenleitschaufeln und deren optimale Gestaltung zur Erhoehung der Effektivitaet von Luftstrahltriebwerken und anderen Gasturbinen

Available from TIB Hannover: DW 4359 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

OVERVIEW: PROCESS PARAMETERS FORHYDROTHERMAL SYNTHESIS OF HYDROXYAPATITE

Hydroxyapatite is the most interesting subject to be studied especially for its suitability as an alternative to human bone and has become a biomaterial ceramic that resembles the composition of our bone minerals and are able to respond biologically. The preferred synthesis method is Hydrothermal which produces HA nano-sized particles with customized morphology and desired crystallinity by varying the process parameters. The morphology and the crystallinity of the synthetic powder particles influence the mechanical properties of manufactured products. This paper reviews the variable factors in hydrothermal method which includes type and concentration of starting material, temperature, time, pressure and pH conditions and presence of additives

التأثير التثبيطي لسلفونات صويا الصوديوم تجاه تآكل الألمونيوم في حمض الهيدروكلوريك

The dissolution of aluminium in 2M hydrochloric acid in the presence of sodium soya sulphonate (SSS) as corrosion inhibitor has been studied using hydrogen evolution and thermometric methods. The two methods gave consistent results. The results obtained indicate that the inhibitive effect of the sulphonated mixture relates to chemisorption mechanism on the metal surface via the n electrons in the double bonds.تمت دراسة ذوبان الألمونيوم في محلول 2 مولارى من حمض الهيدروكلوريك في وجود سلفونات صويا الصوديوم كمثبط للتأكل باستخدام طريقة التصاعد الهيدروجيني والطريقة الحرارية . وقد أعطيت الطريقتان نتائج متطابقة . وقد بينت النتائج أن التأثير التثبيطي للسلفونات يعود إلى ادمصاصها على سطح الفلز من خلال الكترونات الباي الموجودة في الروابط الزوجية في مركبات السلفونات

Synthesis and Characterization of Extractive Scintillating Resin for Ultra-Trace-Level Quantification of Uranium in Aqueous Media

The detection and quantification of radionuclides in aqueous media is of interest to both the Environmental Protection Agency, for matters of public health, and international organizations like the Comprehensive Test Ban Treaty Organization, that use environmental samples to investigate claims of illicit nuclear activities. The current method of quantification involves batch style analytical techniques which utilize bulky instruments. Portable, flow cell detectors utilizing extractive scintillating resin with physically sorbed extractants and fluorophores have been developed; however, this resin shows poor long term stability as the active components leach from the resin over time. There is a need to develop chemically and mechanically stable extractive scintillating resin for flow cell detectors

Direct gamma-ray measurement of different radionuclides in the surface water of Suez Canal

The radioactivity levels of naturally-occurring 238U, 232Th, 226Ra and 40K and anthropogenic 137Cs in surface water from eight locations in the Suez Canal have been assessed by gamma-ray spectrometry. The samples were further characterized by determination of the common cations and anions using ion chromatography. A comparison of 137Cs radioactivity levels in surface water from the Suez Canal with those of other sea waters is presented. The radioactivity levels of 238U, 232Th, 226Ra and 40K from sea water are also reported. The effect of total dissolved solids (TDS), chloride, sulphate ion concentrations on the radioactivity levels of 238U, 232Th and 226Ra is discussed