An instrument for internal standard flame photometry and its application to the determination of calcium in the rare earths

Details are given for simple modifications of a laboratory monochromator so that selected internal standard line pairs from flame spectra may be isolated and measured simultaneoualy with a multiplier phototube differential photometer. The basic design is applicable to most spectrometers or spectrographs. An atomizing system with provisions for sample recycling and recovery is also described. This equipment has been applied to the determination of calcium in the rare earths in the concentration range of 0.025 to 2.5%. Average deviation for a series of repeated determinations at various concentrations is about plus or minus 1.5%

Quantitative separation of small amounts of rare earths from thorium, uranium, and zirconium by ion exchange

A successful method has been developed for the determination of certain rare earths in thorium in the fractional ppm range. The procedure is based on the ion-exchange chromatographic separation of the rare earths plus added yttrium carrier from the thorium, followed by emission spectrometric determination of the rare-earth impurities in the yttrium carrier. A simultaneous separation from the rare earths of the common element impurities present in the thorium has been accomplished. A high degree of compensation for procedural errors is achieved by the use of a pure rare earth as both the carrier in the separation and purification procedure and the matrix material in the spectrographic determination

Lysine Effect on Ruthenium Red and Alcian Blue Preservation and Staining of the Staphylococcal Glycocalyx

The effect of lysine on ruthenium red (RR) and alcian blue (AB) preservation arid/or staining for transmission electron microscopy of glycocalyces was evaluated for three species of the gram-positive, coagulase-negative staphylococci. A RR and an AB procedure were compared with and without lysine included in the glutaraldehyde prefixation. Minimal or no glycocalyx was preserved or stained by glutaraldehyde fixation only. For all species, the inclusion of lysine increased visualization of fibrous material. RR treatment without lysine, results in sparse or limited fibrous material or artifactual condensations which contrasts with enhanced fibrous material seen when lysine is included with RR. The effect of lysine is also to enhance the visualization of staphylococcal glycocalyx by AB. Without lysine, condensed curved structures are consistently seen following AB processing. In contrast, extensive and elaborate glycocalyces are observed with inclusion of lysine with AB. Thus, ultrastructural visualization by RR and AB of the staphylococcal glycocalyx in the species studied was enhanced by use of lysine

Impact of the slaughter process on the pork carcasses contamination by Yersinia entrocolitica

The aim of the study was to evaluate the impact of the tongue handling practice on the contamination of the pork carcasses: the tongue removed with the pluck set (3 slaughterhouses) vs the intact tongue inside the head (3 slaughterhouses). A total of 1920 pigs from 120 different farms were sampled both on their tonsils and carcass surfaces over a one year period. The individual prevalence of Y. enterocolitica on tonsils and carcasses was unexpectedly low and estimated respectively to be 5.7% [4.7-6.9] and 0.6% [0.3-1.0] from the pooled samples. The presence of Y. enterocolitica on the carcasses was statistically linked to its presence on tonsils. It was nearly five times higher on pigs with positive tonsils, than on pigs with negative tonsils. Despite the experimental design, we were not able to confirm that the removal of the tongue on the slaughter line had a significant impact on the carcass contamination with Yersinia enterocolitica. These results confirm that cross contaminations occur during the slaughtering process and that good hygiene practices are necessary to limit the transfer of Y. enterocolitca from the tonsils, or the feces, to the carcasses

Studies on the preparation, properties and analysis of high purity yttrium oxide and yttrium metal at the Ames Laboratory

The research and development work carried out at the Ames Laboratory on the chemistry and metallurgy of yttrium is described in detail in this report or companion reports to which references are herein made. Discussions of the separation of yttrium from the rare-earth elements by ion exchange, of comprehensive investigations of the preparation of yttrium fluoride, and of various ways of reducing the fluoride to the metallic state are presented. Chemical and spectrographic methods of analyzing yttrium and its compounds for oxygen and other impurities are described and comparisons made between the different methods. A pilot plant process for producing tonnage quantities of yttrium metal is presented with detailed descriptions of the equipment and operating procedures employed. The complete process entails the extraction of an yttrium and rare earth mixture from xenotime sand, separation of the yttrium from this mixture in thirty-inch-diameter columns, hydrofluorination of the resulting oxide and its subsequent reduction to the metal. The basic metal process consists of the reduction of yttrium fluoride with calcium, forming a low melting yttrium-magnesium alloy. The magnesium is subsequently removed by vacuum sublimation, producing a porous yttrium product. This is consolidated by vacuum arc melting into a six-inch-diameter ingot. Quantities of high purity yttrium metal were prepared by vacuum distillation and by-a sa,lt extraction refining process. Yttrium metal containing 100 to 300 ppm oxygen is soft, ductile and easily fabricated at room temperature

Automated on-line determination of PPB levels of sodium and potassium in low-Btu coal gas and fluidized bed combustor exhaust by atomic emission spectrometry

The Morgantown Energy Technology Center (METC), US Department of Energy, is involved in the development of processes and equipment for production of low-Btu gas from coal and for fluidized bed combustion of coal. The ultimate objective is large scale production of electricity using high temperature gas turbines. Such turbines, however, are susceptible to accelerated corrosion and self-destruction when relatively low concentrations of sodium and potassium are present in the driving gas streams. Knowledge and control of the concentrations of those elements, at part per billion levels, are critical to the success of both the gas cleanup procedures that are being investigated and the overall energy conversion processes. This presentation describes instrumentation and procedures developed at the Ames Laboratory for application to the problems outlined above and results that have been obtained so far at METC. The first Ames instruments, which feature an automated, dual channel flame atomic emission spectrometer, perform the sodium and potassium determinations simultaneously, repetitively, and automatically every two to three minutes by atomizing and exciting a fraction of the subject gas sample stream in either an oxyhydrogen flame or a nitrous oxide-acetylene flame. The analytical results are printed and can be transmitted simultaneously to a process control center

Specifications for an inductively coupled plasma simultaneous multielement analysis system

Specifications are presented for those items of hardware, software, and overall system performance which are of known importance in atomic emission spectroscopy--simultaneous multielement analyses (ICP-SMA) instrument systems. Particular attention is directed to the specified data reporting and quality assurance features which are required for improving the validity and interpretability of the analytical results, and the specified background correction procedures which are necessary for accurate quantitative determinations near the limit of detection. The specification package was prepared to specify and purchase an ICP-SMA system which will provide maximum value and utility for the simultaneous determination of major, minor and trace quantities of the elements in a wide variety of sample materials. Modifications of the analytical line array specified here may be appropriate for other, more specific, analytical tasks. Budgetary realities may necessitate additional, appropriate modifications. It is anticipated, however, that the specification package presented here will have general utility as a guide in the preparation of ICP-SMA procurement packages for other laboratories and other analytical applications

c-Type Cytochrome-Dependent Formation of U(IV) Nanoparticles by Shewanella oneidensis

Modern approaches for bioremediation of radionuclide contaminated environments are based on the ability of microorganisms to effectively catalyze changes in the oxidation states of metals that in turn influence their solubility. Although microbial metal reduction has been identified as an effective means for immobilizing highly-soluble uranium(VI) complexes in situ, the biomolecular mechanisms of U(VI) reduction are not well understood. Here, we show that c-type cytochromes of a dissimilatory metal-reducing bacterium, Shewanella oneidensis MR-1, are essential for the reduction of U(VI) and formation of extracelluar UO (2) nanoparticles. In particular, the outer membrane (OM) decaheme cytochrome MtrC (metal reduction), previously implicated in Mn(IV) and Fe(III) reduction, directly transferred electrons to U(VI). Additionally, deletions of mtrC and/or omcA significantly affected the in vivo U(VI) reduction rate relative to wild-type MR-1. Similar to the wild-type, the mutants accumulated UO (2) nanoparticles extracellularly to high densities in association with an extracellular polymeric substance (EPS). In wild-type cells, this UO (2)-EPS matrix exhibited glycocalyx-like properties and contained multiple elements of the OM, polysaccharide, and heme-containing proteins. Using a novel combination of methods including synchrotron-based X-ray fluorescence microscopy and high-resolution immune-electron microscopy, we demonstrate a close association of the extracellular UO (2) nanoparticles with MtrC and OmcA (outer membrane cytochrome). This is the first study to our knowledge to directly localize the OM-associated cytochromes with EPS, which contains biogenic UO (2) nanoparticles. In the environment, such association of UO (2) nanoparticles with biopolymers may exert a strong influence on subsequent behavior including susceptibility to oxidation by O (2) or transport in soils and sediments

Safety and efficacy of tenecteplase in patients with wake-up stroke assessed by non-contrast CT (TWIST): a multicentre, open-label, randomised controlled trial

Background: Current evidence supports the use of intravenous thrombolysis with alteplase in patients with wake-up stroke selected with MRI or perfusion imaging and is recommended in clinical guidelines. However, access to advanced imaging techniques is often scarce. We aimed to determine whether thrombolytic treatment with intravenous tenecteplase given within 4·5 h of awakening improves functional outcome in patients with ischaemic wake-up stroke selected using non-contrast CT. Methods: TWIST was an investigator-initiated, multicentre, open-label, randomised controlled trial with blinded endpoint assessment, conducted at 77 hospitals in ten countries. We included patients aged 18 years or older with acute ischaemic stroke symptoms upon awakening, limb weakness, a National Institutes of Health Stroke Scale (NIHSS) score of 3 or higher or aphasia, a non-contrast CT examination of the head, and the ability to receive tenecteplase within 4·5 h of awakening. Patients were randomly assigned (1:1) to either a single intravenous bolus of tenecteplase 0·25 mg per kg of bodyweight (maximum 25 mg) or control (no thrombolysis) using a central, web-based, computer-generated randomisation schedule. Trained research personnel, who conducted telephone interviews at 90 days (follow-up), were masked to treatment allocation. Clinical assessments were performed on day 1 (at baseline) and day 7 of hospital admission (or at discharge, whichever occurred first). The primary outcome was functional outcome assessed by the modified Rankin Scale (mRS) at 90 days and analysed using ordinal logistic regression in the intention-to-treat population. This trial is registered with EudraCT (2014–000096–80), ClinicalTrials.gov (NCT03181360), and ISRCTN (10601890). Findings: From June 12, 2017, to Sept 30, 2021, 578 of the required 600 patients were enrolled (288 randomly assigned to the tenecteplase group and 290 to the control group [intention-to-treat population]). The median age of participants was 73·7 years (IQR 65·9–81·1). 332 (57%) of 578 participants were male and 246 (43%) were female. Treatment with tenecteplase was not associated with better functional outcome, according to mRS score at 90 days (adjusted OR 1·18, 95% CI 0·88–1·58; p=0·27). Mortality at 90 days did not significantly differ between treatment groups (28 [10%] patients in the tenecteplase group and 23 [8%] in the control group; adjusted HR 1·29, 95% CI 0·74–2·26; p=0·37). Symptomatic intracranial haemorrhage occurred in six (2%) patients in the tenecteplase group versus three (1%) in the control group (adjusted OR 2·17, 95% CI 0·53–8·87; p=0·28), whereas any intracranial haemorrhage occurred in 33 (11%) versus 30 (10%) patients (adjusted OR 1·14, 0·67–1·94; p=0·64). Interpretation: In patients with wake-up stroke selected with non-contrast CT, treatment with tenecteplase was not associated with better functional outcome at 90 days. The number of symptomatic haemorrhages and any intracranial haemorrhages in both treatment groups was similar to findings from previous trials of wake-up stroke patients selected using advanced imaging. Current evidence does not support treatment with tenecteplase in patients selected with non-contrast CT. Funding: Norwegian Clinical Research Therapy in the Specialist Health Services Programme, the Swiss Heart Foundation, the British Heart Foundation, and the Norwegian National Association for Public Health