Atmospheric corrosion of austenitic stainless steels

Atmospheric corrosion was investigated using electrochemical and droplet studies. The effects of changes in bulk solution concentration and local pit chemistry on pit propagation and repassivation of 304L and 316L stainless steels were investigated using $in$ $situ$ synchrotron X-radiation and electrochemical techniques. Radiography and zig-zag electrochemical sweeps showed that in dilute chloride solutions, partial passivation was observed to initiate locally and propagate across the corroding surface. This caused repassivation gradually rather than as a uniform event. In concentrated chloride solutions, repassivation did not show a sudden drop in current but rather a gradual decrease as potential swept down. Pitting behaviour was also affected by solution concentration. Dilute solutions showed metastable pitting followed by a sharp breakdown (pitting) potential. Concentrated solutions however showed no metastability and a gradual increase in current when pitting. To determine the cause of current oscillations in 304L artificial pits in NaCl:NaNO$_3$ solutions near the repassivation potential, the salt layers were scanned $in$ $situ$ using XRD. The salt layer was confirmed to be FeCl$_2$.4H$_2$O and no nitrate salt was found. A mechanism was suggested to explain the current oscillations in terms of partial passivation being undercut by the advancing corrosion front

An Unstructured CFD Mini-Application for the Performance Prediction of a Production CFD Code

Maintaining the performance of large scientific codes is a difficult task. To aid in this task, a number of mini-applications have been developed that are more tractable to analyze than large-scale production codes while retaining the performance characteristics of them. These “mini-apps” also enable faster hardware evaluation and, for sensitive commercial codes, allow evaluation of code and system changes outside of access approval processes. In this paper, we develop MG-CFD, a mini-application that represents a geometric multigrid, unstructured computational fluid dynamics (CFD) code, designed to exhibit similar performance characteristics without sharing commercially sensitive code. We detail our experiences of developing this application using guidelines detailed in existing research and contributing further to these. Our application is validated against the inviscid flux routine of HYDRA, a CFD code developed by Rolls-Royce plc for turbomachinery design. This paper (1) documents the development of MG-CFD, (2) introduces an associated performance model with which it is possible to assess the performance of HYDRA on new HPC architectures, and (3) demonstrates that it is possible to use MG-CFD and the performance models to predict the performance of HYDRA with a mean error of 9.2% for strong-scaling studies

Developing and Using a Geometric Multigrid, Unstructured Grid Mini-Application to Assess Many-Core Architectures

Achieving high-performance of large scientific codes is a difficult task. This has led to the development of numerous mini-applications that are more tractable to analyse, while retaining performance characteristics of their full-sized counterparts. These 'mini-apps' also enable faster hardware evaluation, and for sensitive codes allow evaluation of systems outside of access approval processes. In this paper we develop a mini-application of a geometric multigrid, unstructured grid Computational Fluid Dynamics (CFD) code, designed to exhibit similar performance characteristics without sharing code. We detail our experiences developing this application, using guidelines detailed in existing research, and contribute further additions to these to aid future mini-application developers. Our application is validated against the inviscid flux routine of HYDRA, a CFD code developed by Rolls-Royce, which confirms that the parent kernel and mini-application share fundamental causes of parallel inefficiency. We then use the mini-application to assess the impact of Intel's Knights Landing (KNL) on performance. We find that the mini-app and parent kernel continue to share scaling characteristics, however a comparison with Broadwell performance exposed significant differences between the kernels that were undetected by the validation

Evaluation of the influence of kyphosis and scoliosis on intervertebral disc extrusion in French bulldogs

Although thoracic vertebral malformations with kyphosis and scoliosis are often considered incidental findings on diagnostic imaging studies of screw-tailed brachycephalic breeds, they have been suggested to interfere with spinal biomechanics and intervertebral disc degeneration. It is however unknown if an abnormal spinal curvature also predisposes dogs to develop clinically relevant intervertebral disc herniations. The aim of this study was to evaluate if the occurrence of thoracic vertebral malformations, kyphosis or scoliosis would be associated with a higher prevalence of cervical or thoracolumbar intervertebral disc extrusion in French bulldogs

LSST: from Science Drivers to Reference Design and Anticipated Data Products

(Abridged) We describe here the most ambitious survey currently planned in the optical, the Large Synoptic Survey Telescope (LSST). A vast array of science will be enabled by a single wide-deep-fast sky survey, and LSST will have unique survey capability in the faint time domain. The LSST design is driven by four main science themes: probing dark energy and dark matter, taking an inventory of the Solar System, exploring the transient optical sky, and mapping the Milky Way. LSST will be a wide-field ground-based system sited at Cerro Pach\'{o}n in northern Chile. The telescope will have an 8.4 m (6.5 m effective) primary mirror, a 9.6 deg$^2$ field of view, and a 3.2 Gigapixel camera. The standard observing sequence will consist of pairs of 15-second exposures in a given field, with two such visits in each pointing in a given night. With these repeats, the LSST system is capable of imaging about 10,000 square degrees of sky in a single filter in three nights. The typical 5$\sigma$ point-source depth in a single visit in $r$ will be $\sim 24.5$ (AB). The project is in the construction phase and will begin regular survey operations by 2022. The survey area will be contained within 30,000 deg$^2$ with $\delta<+34.5^\circ$, and will be imaged multiple times in six bands, $ugrizy$, covering the wavelength range 320--1050 nm. About 90\% of the observing time will be devoted to a deep-wide-fast survey mode which will uniformly observe a 18,000 deg$^2$ region about 800 times (summed over all six bands) during the anticipated 10 years of operations, and yield a coadded map to $r\sim27.5$. The remaining 10\% of the observing time will be allocated to projects such as a Very Deep and Fast time domain survey. The goal is to make LSST data products, including a relational database of about 32 trillion observations of 40 billion objects, available to the public and scientists around the world.Comment: 57 pages, 32 color figures, version with high-resolution figures available from https://www.lsst.org/overvie

Significant benefits of AIP testing and clinical screening in familial isolated and young-onset pituitary tumors

Context Germline mutations in the aryl hydrocarbon receptor-interacting protein (AIP) gene are responsible for a subset of familial isolated pituitary adenoma (FIPA) cases and sporadic pituitary neuroendocrine tumors (PitNETs). Objective To compare prospectively diagnosed AIP mutation-positive (AIPmut) PitNET patients with clinically presenting patients and to compare the clinical characteristics of AIPmut and AIPneg PitNET patients. Design 12-year prospective, observational study. Participants & Setting We studied probands and family members of FIPA kindreds and sporadic patients with disease onset ≤18 years or macroadenomas with onset ≤30 years (n = 1477). This was a collaborative study conducted at referral centers for pituitary diseases. Interventions & Outcome AIP testing and clinical screening for pituitary disease. Comparison of characteristics of prospectively diagnosed (n = 22) vs clinically presenting AIPmut PitNET patients (n = 145), and AIPmut (n = 167) vs AIPneg PitNET patients (n = 1310). Results Prospectively diagnosed AIPmut PitNET patients had smaller lesions with less suprasellar extension or cavernous sinus invasion and required fewer treatments with fewer operations and no radiotherapy compared with clinically presenting cases; there were fewer cases with active disease and hypopituitarism at last follow-up. When comparing AIPmut and AIPneg cases, AIPmut patients were more often males, younger, more often had GH excess, pituitary apoplexy, suprasellar extension, and more patients required multimodal therapy, including radiotherapy. AIPmut patients (n = 136) with GH excess were taller than AIPneg counterparts (n = 650). Conclusions Prospectively diagnosed AIPmut patients show better outcomes than clinically presenting cases, demonstrating the benefits of genetic and clinical screening. AIP-related pituitary disease has a wide spectrum ranging from aggressively growing lesions to stable or indolent disease course

Catalytic Conversion of Ethanol to <i>n</i>‑Butanol Using Ruthenium P–N Ligand Complexes

We report several ruthenium catalysts incorporating mixed donor phosphine-amine ligands for the upgrade of ethanol to the advanced biofuel <i>n</i>-butanol, which show high selectivity (≥90%) at good (up to 31%) conversion. In situ formation of catalysts from mixtures of [RuCl₂(η⁶-<i>p</i>-cymene)]₂ and 2-(diphenylphosphino)­ethylamine (<b>1</b>) shows enhanced activity at initial water concentrations higher than those of our previously reported diphosphine systems. Preliminary mechanistic studies (electrospray ionization mass spectrometry and nuclear magnetic resonance spectroscopy) suggest the possibility of ligand-assisted proton transfer in some derivatives

Keystrokes, Mouse Clicks, and Gazing at the Computer: How Physician Interaction with the EHR Affects Patient Participation

BackgroundEvidence is mixed regarding how physicians' use of the electronic health record (EHR) affects communication in medical encounters.ObjectiveTo investigate whether the different ways physicians interact with the computer (mouse clicks, key strokes, and gaze) vary in their effects on patient participation in the consultation, physicians' efforts to facilitate patient involvement, and silence.DesignCross-sectional, observational study of video and event recordings of primary care and specialty consultations.ParticipantsThirty-two physicians and 217 patients.Main measuresPredictor variables included measures of physician interaction with the EHR (mouse clicks, key strokes, gaze). Outcome measures included active patient participation (asking questions, stating preferences, expressing concerns), physician facilitation of patient involvement (partnership-building and supportive talk), and silence.Key resultsPatients were less active participants in consultations in which physicians engaged in more keyboard activity (b = -0.002, SE = 0.001, p = 0.02). More physician gaze at the computer was associated with more silence in the encounter (b = 0.21, SE = 0.09, p = 0.02). Physicians' facilitative communication, which predicted more active patient participation (b = 0.65, SE = 0.14, p &lt; 0.001), was not related to EHR activity measures.ConclusionsPatients may be more reluctant to actively participate in medical encounters when physicians are more physically engaged with the computer (e.g., keyboard activity) than when their behavior is less demonstrative (e.g., gazing at EHR). Using easy to deploy communication tactics (e.g., asking about a patient's thoughts and concerns, social conversation) while working on the computer can help physicians engage patients as well as maintain conversational flow

Keystrokes, Mouse Clicks, and Gazing at the Computer: How Physician Interaction with the EHR Affects Patient Participation

BackgroundEvidence is mixed regarding how physicians' use of the electronic health record (EHR) affects communication in medical encounters.ObjectiveTo investigate whether the different ways physicians interact with the computer (mouse clicks, key strokes, and gaze) vary in their effects on patient participation in the consultation, physicians' efforts to facilitate patient involvement, and silence.DesignCross-sectional, observational study of video and event recordings of primary care and specialty consultations.ParticipantsThirty-two physicians and 217 patients.Main measuresPredictor variables included measures of physician interaction with the EHR (mouse clicks, key strokes, gaze). Outcome measures included active patient participation (asking questions, stating preferences, expressing concerns), physician facilitation of patient involvement (partnership-building and supportive talk), and silence.Key resultsPatients were less active participants in consultations in which physicians engaged in more keyboard activity (b = -0.002, SE = 0.001, p = 0.02). More physician gaze at the computer was associated with more silence in the encounter (b = 0.21, SE = 0.09, p = 0.02). Physicians' facilitative communication, which predicted more active patient participation (b = 0.65, SE = 0.14, p &lt; 0.001), was not related to EHR activity measures.ConclusionsPatients may be more reluctant to actively participate in medical encounters when physicians are more physically engaged with the computer (e.g., keyboard activity) than when their behavior is less demonstrative (e.g., gazing at EHR). Using easy to deploy communication tactics (e.g., asking about a patient's thoughts and concerns, social conversation) while working on the computer can help physicians engage patients as well as maintain conversational flow

Stereoretentive enantioconvergent reactions

The stereoselective synthesis of chiral molecules in enantioenriched form – i.e., asymmetric synthesis – underpins many fields of pure and applied science. Enantioconvergent reactions are preeminent in contemporary asymmetric synthesis as they convert both enantiomers of a racemic starting material into a single enantioenriched product, thus avoiding the maximum 50% yield associated with resolutions. All currently known enantioconvergent processes necessitate the loss or partial-loss of the racemic substrate’s configuration, thus limiting the potential substrate scope to molecules that contain labile stereogenic units. Here we present a new approach to enantioconvergent reactions that can proceed with full retention of the racemic substrate’s configuration. This uniquely stereo-economic approach is possible if the two enantiomers of a racemic starting material are joined together to form one enantiomer of a non-meso product. Experimental validation of this concept is presented using two distinct strategies; (1) a direct unsymmetrical coupling approach and (2) a multi-component approach, which exhibits statistical-amplification of enantiopurity. Our results demonstrate that stereoretentive-enantioconvergent reactions can be achieved using a wide variety of synthetic tactics, including stoichiometric chiral reagents, chiral auxiliaries, and chiral catalysts. Thus, the established dogma that enantioconvergent reactions require substrates that contain labile stereogenic units is shown to be incorrect. We anticipate the concept of stereoretention in enantioconvergent reactions will lead to the development of novel methodologies that can utilize a hitherto unexplored range of racemic substrates