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1.
Clin Exp Dermatol ; 48(4): 345-351, 2023 Mar 22.
Artigo em Inglês | MEDLINE | ID: mdl-36763771

RESUMO

BACKGROUND: Dermatology faces a workforce crisis against a backdrop of wider medical education shifts towards generalism. A pivot towards generalism may have an impact on dermatology trainee professional identity, which, to our knowledge, has not been investigated and is known to have an impact on competence and conceptualization of ethics among physicians. Disruption because of the COVID-19 pandemic led to dermatology trainee redeployment and therefore presents a unique opportunity to examine dermatology trainee professional identity during times of pressure. AIM: To identify the impact of COVID-19 redeployment on dermatology trainee professional identity, the factors influencing identity and whether such factors affect trainees' perceptions about their future careers. METHODS: Ten trainees were purposively recruited to the study. Data were collected through semistructured interviews and were analysed phenomenologically using the template analysis method. Central and integrative themes were identified. RESULTS: Three central themes were identified: trainee identity and values; redeployment transitions; and future clarity. Three integrative themes were found: tribes; sense of purpose; and uncertainty. Trainees see competence and community as central to the dermatologist identity. Most trainees experienced a reaffirmation of their prior values, psychologically retreating to close-knit communities. However, some underwent disorienting dilemmas, later reflecting on their futures as dermatologists. CONCLUSION: Healthcare crises may have a significant impact on dermatology trainee professional identity and may lead to reaffirmation of prior tribal values or disorienting reflection upon future career trajectories. Improved support among diverse communities, minimization of uncertainty and fostering a sense of purpose among trainees may aid identity enrichment and safeguard the future dermatology consultant workforce.


Assuntos
COVID-19 , Dermatologia , Humanos , Dermatologistas , Dermatologia/educação , Crise de Identidade , Pandemias
2.
ACS Appl Mater Interfaces ; 12(14): 16327-16341, 2020 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-32180402

RESUMO

Ce-bastnäsite is the single largest mineral source for light rare-earth elements. In view of the growing industrial importance of rare-earth minerals, it is critical to develop more efficient methods for separating the valuable rare-earth-containing minerals from the surrounding gangue. In this work, we employ a combination of periodic density functional theory (DFT) and molecular mechanics (MM) calculations together with the de novo molecular design program HostDesigner to identify bis-phosphinate ligands that preferentially bind to the (100) Ce-bastnäsite surface rather than the (104) calcite surface. DFT calculations for a simple phosphinate ligand were employed to qualitatively understand key behaviors involved in ligand-metal, ligand-solvent, and solvent-metal interactions. These insights were then used to guide the search for flexible, rigid, and semirigid hydrocarbon linkers to identify candidate bis-phosphinate ligands with the potential to bind preferentially to Ce-bastnäsite. Among the five most promising bis-phosphinate ligands suggested by theoretical studies, three ligands were synthesized and their adsorption characteristics to bastnäsite (100) interfaces were characterized using vibrational sum-frequency (vSFG) spectroscopy, attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, and isothermal titration calorimetry (ITC). The efficacy of the selective interfacial molecular binding was demonstrated by identifying a bis-phosphinate ligand capable of providing an overall higher surface coverage of alkyl groups relative to a monophosphinate ligand. The results highlight the interplay between adsorption binding strength and maximum surface coverage in determining ligand efficiency to render the mineral surface hydrophobic. DFT calculations further indicate that all tested ligands have higher affinity for Ce-bastnäsite than for calcite. This is consistent with the ITC data showing stronger adsorption enthalpy to bastnäsite than to calcite, making these ligands promising candidates for selective flotation of Ce-bastnäsite.

4.
J Phys Condens Matter ; 30(29): 295901, 2018 Jul 25.
Artigo em Inglês | MEDLINE | ID: mdl-29882745

RESUMO

Lattice based kinetic Monte Carlo (KMC) is often used for simulating the dynamics of systems at a supramolecular scale, based on molecular scale transitions. A common challenge in KMC simulations is rapid 'back-and-forth' reactions, which dominate the events executed during simulations and inhibit the ability for simulations to reach longer time scales. Such processes are fast frivolous processes (FFPs) and are one manifestation of a phenomenon referred to as KMC-stiffness. Here, an algorithm for staggered quasi-equilibrium rank-based throttling geared towards transient kinetics (SQERT-T) is presented. Within the SQERT-T methodology, a pace-restrictor reaction and an FFP floor are utilized along with throttling of the process transition rate constants to accelerate the KMC simulations while still retaining sufficient time resolution for sampling of the data. KMC simulations were performed for CO oxidation over RuO2(1 1 0) and over RuO2(1 1 1), and the results were compared to experimental data obtained using RuO2 powders. The experiments and simulations were for transient conditions: the system was subjected to a temperature program which included temperatures in the range of 363 to 453 K. The timescales that were achieved during the KMC simulations in this study would not have been accessible without KMC acceleration, and were enabled by the use of SQERT-T.

5.
J Phys Chem Lett ; 8(23): 5810-5814, 2017 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-29136471

RESUMO

Upgrading of primary alcohols by C-H bond breaking currently requires temperatures of >200 °C. In this work, new understanding from simulation of a temperature-programmed reaction study with methanol over a CeO2(111) surface shows C-H bond breaking and the subsequent desorption of formaldehyde, even below room temperature. This is of particular interest because CeO2 is a naturally abundant and inexpensive metal oxide. We combine density functional theory and kinetic Monte Carlo methods to show that the low-temperature C-H bond breaking occurs via disproportionation of adjacent methoxy species. We further show from calculations that the same transition state with comparable activation energy exists for other primary alcohols; with ethanol, 1-propanol, and 1-butanol explicitly calculated. These findings indicate a promising class of transition states to search for in seeking low-temperature C-H bond breaking over inexpensive oxides.

6.
Nat Chem ; 8(4): 331-7, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-27001728

RESUMO

Kinetic models based on first principles are becoming common place in heterogeneous catalysis because of their ability to interpret experimental data, identify the rate-controlling step, guide experiments and predict novel materials. To overcome the tremendous computational cost of estimating parameters of complex networks on metal catalysts, approximate quantum mechanical calculations are employed that render models potentially inaccurate. Here, by introducing correlative global sensitivity analysis and uncertainty quantification, we show that neglecting correlations in the energies of species and reactions can lead to an incorrect identification of influential parameters and key reaction intermediates and reactions. We rationalize why models often underpredict reaction rates and show that, despite the uncertainty being large, the method can, in conjunction with experimental data, identify influential missing reaction pathways and provide insights into the catalyst active site and the kinetic reliability of a model. The method is demonstrated in ethanol steam reforming for hydrogen production for fuel cells.

7.
Langmuir ; 29(7): 2193-9, 2013 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-23360298

RESUMO

Bioinspired bottom-up assembly and layer-by-layer (LbL) construction of inorganic materials from lithographically defined organic templates enables the fabrication of nanostructured systems under mild temperature and pH conditions. Such processes open the door to low-impact manufacturing and facile recycling of hybrid materials for energy, biology, and information technologies. Here, templated LbL assembly of silica was achieved using a combination of electron beam lithography, chemical lift-off, and aqueous solution chemistry. Nanopatterns of lines, honeycomb-lattices, and dot arrays were defined in polymer resist using electron beam lithography. Following development, exposed areas of silicon were functionalized with a vapor deposited amine-silane monolayer. Silicic acid solutions of varying pH and salt content were reacted with the patterned organic amine-functional templates. Vapor treatment and solution reaction could be repeated, allowing LbL deposition. Conditions for the silicic acid deposition had a strong effect on thickness of each layer, and the morphology of the amorphous silica formed. "Defects" in the arrays of silica nanostructures were minor and do not affect the overall organization of the layers. The bioinspired method described here facilitates the bottom-up assembly of inorganic nanostructures defined in three dimensions and provides a path, via LbL processing, for the construction of layered hybrid materials under mild conditions.


Assuntos
Nanoestruturas/química , Dióxido de Silício/química , Microscopia de Força Atômica , Microscopia Eletrônica de Varredura , Nanotecnologia
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