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Bennett JW, Jones D, Huang X, Hamers RJ, Mason SE. Dissolution of Complex Metal Oxides from First-Principles and Thermodynamics: Cation Removal from the (001) Surface of Li(Ni 1/3Mn 1/3Co 1/3)O 2. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:5792-5802. [PMID: 29653050 DOI: 10.1021/acs.est.8b00054] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The rapid increase in use of Li-ion batteries in portable electronics has created a pressing need to understand the environmental impact and long-term fate of electonic waste (e-waste) products such as heavy and/or reactive metals. The type of e-waste that we focus on here are the complex metal oxide nanomaterials that compose Li-ion battery cathodes. While in operation the complex metal oxides are in a hermetically sealed container. However, at the end of life, improper disposal can cause structural transformations such as dissolution and metal leaching, resulting in a significant exposure risk to the surrounding environment. The transformations that occur between operational to environmental settings gives rise to a stark knowledge gap between macroscopic design and molecular-level behavior. In this study we use theory and modeling to describe and explain previously published experimental data for cation release from Li(Ni1/3Mn1/3Co1/3)O2 (NMC) nanoparticles in an aqueous environment ( Chem. Mater. 2016 (28) 1092-1100). To better understand the transformations that may occur when this material is exposed to the environment, we compute the free energy of surface dissolution, Δ G, from the complex metal oxide NMC for a range of surface terminations and pH.
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Liang D, Hong J, Fang D, Bennett JW, Mason SE, Hamers RJ, Cui Q. Analysis of the conformational properties of amine ligands at the gold/water interface with QM, MM and QM/MM simulations. Phys Chem Chem Phys 2018; 20:3349-3362. [DOI: 10.1039/c7cp06709g] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We describe a strategy of integrating quantum mechanical (QM), hybrid quantum mechanical/molecular mechanical (QM/MM) and MM simulations to analyze the physical properties of a solid/water interface.
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Bennett JW, Bjorklund JL, Forbes TZ, Mason SE. Systematic Study of Aluminum Nanoclusters and Anion Adsorbates. Inorg Chem 2017; 56:13014-13028. [DOI: 10.1021/acs.inorgchem.7b01803] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Corum KW, Mason SE. Using density functional theory to study shape-reactivity relationships in Keggin Al-nanoclusters. WATER RESEARCH 2016; 102:413-420. [PMID: 27393966 DOI: 10.1016/j.watres.2016.06.043] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Revised: 06/17/2016] [Accepted: 06/18/2016] [Indexed: 06/06/2023]
Abstract
Keggin-based aluminum nanoclusters have been shown to be efficient sorbents for the removal of arsenic from water. Obtaining a molecular-level understanding of the adsorption processes associated with these molecules is of fundamental importance, and could pave the way for rational design strategies for water treatment. Due to their size and the availability of experimental crystal structures, Al nanoclusters are computationally tractable at the density functional theory (DFT) level. Here, we compare the reactivity of three aluminum polycations: [Al13O4(OH)24(H2O)12](7+) (Al13), [Al30O8(OH)56(H2O)26](18+) (Al30), and [Al32O8(OH)60(H2O)30](20+) (Al32). We use DFT calculations to determine reactivity as a function of particle topography, using sulfate and chloride as adsorption probes. Our comparative modeling of outer-sphere adsorption of Cl(-) and SO4(2-) on Al13, Al30, and A132 supports that the unique "hourglass" shape characteristic to Al30 gives rise to relatively strong adsorption in the molecular beltway, as well as a wide range of reaction energies as a function of particle topography.
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Cui Q, Hernandez R, Mason SE, Frauenheim T, Pedersen JA, Geiger F. Sustainable Nanotechnology: Opportunities and Challenges for Theoretical/Computational Studies. J Phys Chem B 2016; 120:7297-306. [PMID: 27388532 DOI: 10.1021/acs.jpcb.6b03976] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
For assistance in the design of the next generation of nanomaterials that are functional and have minimal health and safety concerns, it is imperative to establish causality, rather than correlations, in how properties of nanomaterials determine biological and environmental outcomes. Due to the vast design space available and the complexity of nano/bio interfaces, theoretical and computational studies are expected to play a major role in this context. In this minireview, we highlight opportunities and pressing challenges for theoretical and computational chemistry approaches to explore the relevant physicochemical processes that span broad length and time scales. We focus discussions on a bottom-up framework that relies on the determination of correct intermolecular forces, accurate molecular dynamics, and coarse-graining procedures to systematically bridge the scales, although top-down approaches are also effective at providing insights for many problems such as the effects of nanoparticles on biological membranes.
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Fairley M, Corum KW, Johns A, Unruh DK, Basile M, de Groot J, Mason SE, Forbes TZ. Isolation and characterization of the [Ga2Al18O8(OH)36(H2O)12](8+) cluster: cationic variations on the Wells-Dawson topology. Chem Commun (Camb) 2015; 51:12467-9. [PMID: 26146343 DOI: 10.1039/c5cc03069b] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The structural chemistry of Group 13 polyoxometalates lags far behind related negatively charged transition metal species and limits the development of advanced materials. A novel heterometallic cluster [Ga2Al18O8(OH)36(H2O)12](8+) (Ga2Al18) has been isolated using a supramolecular approach and structurally characterized using single-crystal X-ray diffraction. Ga2Al18 represents the Wells-Dawson structure polycations and variations in the structural topology may be related to the initial stabilization of the Keggin isomer. DFT calculations on the related ε-Keggins (GaAl12 and Al13), Ga2Al18, and theoretical Al2Al18 clusters reveal similar features of electronic structure, suggesting additional heteroatom substitution in other isostructural clusters should be possible.
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Corum KW, Fairley M, Unruh DK, Payne MK, Forbes TZ, Mason SE. Characterization of Phosphate and Arsenate Adsorption onto Keggin-Type Al30 Cations by Experimental and Theoretical Methods. Inorg Chem 2015; 54:8367-74. [DOI: 10.1021/acs.inorgchem.5b01039] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Scott AJ, Mason SE, Arunakirinathan M, Reissis Y, Kinross JM, Smith JJ. Risk stratification by the Appendicitis Inflammatory Response score to guide decision-making in patients with suspected appendicitis. Br J Surg 2015; 102:563-72. [PMID: 25727811 DOI: 10.1002/bjs.9773] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Revised: 08/28/2014] [Accepted: 12/12/2014] [Indexed: 12/29/2022]
Abstract
BACKGROUND Current management of suspected appendicitis is hampered by the overadmission of patients with non-specific abdominal pain and a significant negative exploration rate. The potential benefits of risk stratification by the Appendicitis Inflammatory Response (AIR) score to guide clinical decision-making were assessed. METHODS During this 50-week prospective observational study at one institution, the AIR score was calculated for all patients admitted with suspected appendicitis. Appendicitis was diagnosed by histological examination, and patients were classified as having non-appendicitis pain if histological findings were negative or surgery was not performed. The diagnostic performance of the AIR score and the potential for risk stratification to reduce admissions, optimize imaging and prevent unnecessary explorations were quantified. RESULTS A total of 464 patients were included, of whom 210 (63·3 per cent) with non-appendicitis pain were correctly classified as low risk. However, 13 low-risk patients had appendicitis. Low-risk patients accounted for 48·1 per cent of admissions (223 of 464), 57 per cent of negative explorations (48 of 84) and 50·7 per cent of imaging requests (149 of 294). An AIR score of 5 or more (intermediate and high risk) had high sensitivity for all severities of appendicitis (90 per cent) and also for advanced appendicitis (98 per cent). An AIR score of 9 or more (high risk) was very specific (97 per cent) for appendicitis, and the majority of patients with appendicitis in the high-risk group (21 of 30, 70 per cent) had perforation or gangrene. Ultrasound imaging could not exclude appendicitis in low-risk patients (negative likelihood ratio (LR) 1·0) but could rule-in the diagnosis in intermediate-risk patients (positive LR 10·2). CT could exclude appendicitis in low-risk patients (negative LR 0·0) and rule-in appendicitis in the intermediate group (positive LR 10·9). CONCLUSION Risk stratification of patients with suspected appendicitis by the AIR score could guide decision-making to reduce admissions, optimize utility of diagnostic imaging and prevent negative explorations.
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Mason SE, Nicolay CR, Darzi A. The use of Lean and Six Sigma methodologies in surgery: a systematic review. Surgeon 2014; 13:91-100. [PMID: 25189692 DOI: 10.1016/j.surge.2014.08.002] [Citation(s) in RCA: 170] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Accepted: 08/05/2014] [Indexed: 11/24/2022]
Abstract
BACKGROUND Lean and Six Sigma are improvement methodologies developed in the manufacturing industry and have been applied to healthcare settings since the 1990 s. They use a systematic and reproducible approach to provide Quality Improvement (QI), with a flexible process that can be applied to a range of outcomes across different patient groups. This review assesses the literature with regard to the use and utility of Lean and Six Sigma methodologies in surgery. METHODS MEDLINE, Embase, PsycINFO, Allied and Complementary Medicine Database, British Nursing Index, Cumulative Index to Nursing and Allied Health Literature, Health Business Elite and the Health Management Information Consortium were searched in January 2014. Experimental studies were included if they assessed the use of Lean or Six Sigma on the ability to improve specified outcomes in surgical patients. RESULTS Of the 124 studies returned, 23 were suitable for inclusion with 11 assessing Lean, 6 Six Sigma and 6 Lean Six Sigma. The broad range of outcomes can be collated into six common aims: to optimise outpatient efficiency, to improve operating theatre efficiency, to decrease operative complications, to reduce ward-based harms, to reduce mortality and to limit unnecessary cost and length of stay. The majority of studies (88%) demonstrate improvement; however high levels of systematic bias and imprecision were evident. CONCLUSION Lean and Six Sigma QI methodologies have the potential to produce clinically significant improvement for surgical patients. However there is a need to conduct high-quality studies with low risk of systematic bias in order to further understand their role.
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Mullen KAE, Lee AR, Lyman RL, Mason SE, Washburn SP, Anderson KL. Short communication: an in vitro assessment of the antibacterial activity of plant-derived oils. J Dairy Sci 2014; 97:5587-91. [PMID: 25022682 DOI: 10.3168/jds.2013-7806] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Accepted: 06/05/2014] [Indexed: 11/19/2022]
Abstract
Nonantibiotic treatments for mastitis are needed in organic dairy herds. Plant-derived oils may be useful but efficacy and potential mechanisms of action of such oils in mastitis therapy have not been well documented. The objective of the current study was to evaluate the antibacterial activity of the plant-derived oil components of Phyto-Mast (Bovinity Health LLC, Narvon, PA), an herbal intramammary product, against 3 mastitis-causing pathogens: Staphylococcus aureus, Staphylococcus chromogenes, and Streptococcus uberis. Plant-derived oils evaluated were Thymus vulgaris (thyme), Gaultheria procumbens (wintergreen), Glycyrrhiza uralensis (Chinese licorice), Angelica sinensis, and Angelica dahurica. Broth dilution testing according to standard protocol was performed using ultrapasteurized whole milk instead of broth. Controls included milk only (negative control), milk + bacteria (positive control), and milk + bacteria + penicillin-streptomycin (antibiotic control, at 1 and 5% concentrations). Essential oil of thyme was tested by itself and not in combination with other oils because of its known antibacterial activity. The other plant-derived oils were tested alone and in combination for a total of 15 treatments, each replicated 3 times and tested at 0.5, 1, 2, and 4% to simulate concentrations potentially achievable in the milk within the pre-dry-off udder quarter. Thyme oil at concentrations ≥2% completely inhibited bacterial growth in all replications. Other plant-derived oils tested alone or in various combinations were not consistently antibacterial and did not show typical dose-response effects. Only thyme essential oil had consistent antibacterial activity against the 3 mastitis-causing organisms tested in vitro. Further evaluation of physiological effects of thyme oil in various preparations on mammary tissue is recommended to determine potential suitability for mastitis therapy.
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Corum KW, Mason SE. Establishing trends in ion adsorption on the aqueous aluminium hydroxide nanoparticle Al30. MOLECULAR SIMULATION 2014. [DOI: 10.1080/08927022.2014.895001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Abeysinghe S, Corum KW, Neff DL, Mason SE, Forbes TZ. Contaminant adsorption on nanoscale particles: structural and theoretical characterization of Cu2+ bonding on the surface of Keggin-type polyaluminum (Al30) molecular species. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:14124-14134. [PMID: 24144137 DOI: 10.1021/la402736t] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The adsorption of contaminants onto metal oxide surfaces with nanoscale Keggin-type structural topologies has been well established, but identification of the reactive sites and the exact binding mechanism are lacking. Polyaluminum species can be utilized as geochemical model compounds to provide molecular level details of the adsorption process. An Al30 Keggin-type species with two surface-bound Cu(2+) cations (Cu2Al30-S) has been crystallized in the presence of disulfonate anions and structurally characterized by single-crystal X-ray diffraction. Density functional theory (DFT) calculations of aqueous molecular analogues for Cu2Al30-S suggest that the reactivity of Al30 toward Cu(2+) and SO4(2-) shows opposite trends in preferred adsorption site as a function of particle topology, with anions preferring the beltway and cations preferring the caps. The bonding competition was modeled using two stepwise reaction schemes that consider Cu2Al30-S formation through initial Cu(2+) or SO4(2-) adsorption. The associated DFT energetics and charge density analyses suggest that strong electrostatic interactions between SO4(2-) and the beltway of Al30 play a vital role in governing where Cu(2+) binds. The calculated electrostatic potential of Al30 provides a theoretical interpretation of the topology-dependent reactivity that is consistent with the present study as well as other results in the literature.
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Mason SE, Trainor TP, Goffinet CJ. DFT study of Sb(III) and Sb(V) adsorption and heterogeneous oxidation on hydrated oxide surfaces. COMPUT THEOR CHEM 2012. [DOI: 10.1016/j.comptc.2011.11.031] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Goffinet CJ, Mason SE. Comparative DFT study of inner-sphere As(iii) complexes on hydrated α-Fe2O3(0001) surface models. ACTA ACUST UNITED AC 2012; 14:1860-71. [DOI: 10.1039/c2em30355h] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Mason SE, McShane R, Ritchie CW. Diagnostic tests for Alzheimer's disease: rationale, methodology, and challenges. Int J Alzheimers Dis 2010; 2010. [PMID: 20811564 PMCID: PMC2929623 DOI: 10.4061/2010/972685] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2010] [Accepted: 07/01/2010] [Indexed: 11/20/2022] Open
Abstract
There has been a large increase in the amount of research seeking to define or diagnose Alzheimer's disease before patients develop dementia. If successful, this would principally have clinical benefits both in terms of treatment as well as risk modification. Moreover, a better method for diagnosing predementia disease would assist research which seeks to develop such treatments and risk modification strategies. The evidence-based definition of a diagnostic test's accuracy is fundamental to achieve the above goals and to address this, the Cochrane Collaboration has established a Diagnostic Test Accuracy group dedicated to examining the utility and accuracy of proposed tests in dementia and cognitive impairment. We present here the assumptions and observations underpinning the chosen methodology as well as the initial methodological approach decided upon.
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Mason SE, Iceman CR, Trainor TP, Chaka AM. Molecular-level understanding of environmental interfaces using density functional theory modeling. ACTA ACUST UNITED AC 2010. [DOI: 10.1016/j.phpro.2010.08.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Mason SE, Sokol EA, Cooper VR, Rappe AM. Spontaneous Formation of Dipolar Metal Nanoclusters. J Phys Chem A 2009; 113:4134-7. [DOI: 10.1021/jp8105088] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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Wong JH, Dukes J, Levy RE, Sos B, Mason SE, Fong TS, Weiss EJ. Sex differences in thrombosis in mice are mediated by sex-specific growth hormone secretion patterns. J Clin Invest 2008; 118:2969-78. [PMID: 18618017 DOI: 10.1172/jci34957] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2008] [Accepted: 05/27/2008] [Indexed: 11/17/2022] Open
Abstract
Sex differences in thrombosis are well described, but their underlying mechanism(s) are not completely understood. Coagulation proteins are synthesized in the liver, and liver gene expression is sex specific and depends on sex differences in growth hormone (GH) secretion--males secrete GH in a pulsatile fashion, while females secrete GH continuously. Accordingly, we tested the hypothesis that sex-specific GH secretion patterns cause sex differences in thrombosis. Male mice were more susceptible to thrombosis than females in the thromboplastin-induced pulmonary embolism model and showed shorter clotting times ex vivo. GH-deficient little (lit) mice were protected from thrombosis, and pulsatile GH given to lit mice restored the male clotting phenotype. Moreover, pulsatile GH administration resulted in a male clotting phenotype in control female mice, while continuous GH caused a female clotting phenotype in control male mice. Expression of the coagulation inhibitors Proc, Serpinc1, Serpind1, and Serpina5 were strongly modulated by sex-specific GH patterns, and GH modulated resistance to activated protein C. These results reveal what we believe to be a novel mechanism whereby sex-specific GH patterns mediate sex differences in thrombosis through coordinated changes in the expression of coagulation inhibitor genes in the liver.
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Grinberg I, Suchomel MR, Dmowski W, Mason SE, Wu H, Davies PK, Rappe AM. Structure and polarization in the high Tc ferroelectric Bi(Zn,Ti)O3-PbTiO3 solid solutions. PHYSICAL REVIEW LETTERS 2007; 98:107601. [PMID: 17358566 DOI: 10.1103/physrevlett.98.107601] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2006] [Indexed: 05/14/2023]
Abstract
Theoretical ab initio and experimental methods are used to investigate the [Bi(Zn1/2Ti1/2)O3]x[PbTiO3]1-x solid solution. We find that hybridization between Zn 4s and 4p and O 2p orbitals allows the formation of short, covalent Zn-O bonds, enabling favorable coupling between A-site and B-site displacements. This leads to unusually large polarization, strong tetragonality, and an elevated ferroelectric to paraelectric phase transition temperature.
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Mason SE, Grinberg I, Rappe AM. Adsorbate−Adsorbate Interactions and Chemisorption at Different Coverages Studied by Accurate ab initio Calculations: CO on Transition Metal Surfaces. J Phys Chem B 2006; 110:3816-22. [PMID: 16494441 DOI: 10.1021/jp0548669] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We use density functional theory (DFT) with the generalized gradient approximation (GGA) and our first-principles extrapolation method for accurate chemisorption energies (Mason et al. Phys. Rev. B 2004, 69, 161401R) to calculate the chemisorption energy for CO on a variety of transition metal surfaces for various adsorbate densities and patterns. We identify adsorbate through-space repulsion, bonding competition, and substrate-mediated electron delocalization as key factors determining the preferred chemisorption patterns for different metal surfaces and adsorbate coverages. We discuss how the balance of these interactions, along with the inherent adsorption site preference on each metal surface, can explain the observed CO adsorbate patterns at different coverages.
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Abstract
The need for educating patients about the dangers of unprotected sexual activity is well documented in the literature. Using clinical examples, the authors describe safe-sex strategies for patients experiencing their first episode of schizophrenia. Interventions are based on a 2-year experience of working in a hospital-based treatment and research project with 68 patients. Strategies that begin in the healing phase of schizophrenia take place in both individual and group sessions. First-episode patients are encouraged to speak explicitly about their sex-related behaviors, and HIV testing is suggested when needed. The goal of this approach is to emphasize safe-sex/HIV prevention strategies within a framework of good clinical practice.
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Miller R, Mason SE. Phase-specific psychosocial interventions for first-episode schizophrenia. Bull Menninger Clin 2000; 63:499-519. [PMID: 10589141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
Phase-specific psychosocial interventions for first-episode schizophrenia are outlined and described using examples from clinical practice with 68 patients. These interventions are based on the unique aspects of the first episode and patients' clinical states. Although schizophrenia may run an uneven and often unpredictable course, most patients experience three distinct phases: (1) the acute phase, (2) the healing phase, and (3) the maintenance phase. The timeliness of phase-specific interventions is crucial in helping both patients and families understand the illness, evaluate options, accept treatment, and adjust to changes in functioning and expectations.
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Pawlik CA, Iyengar RV, Krull EJ, Mason SE, Khanna R, Harris LC, Potter PM, Danks MK, Guichard SM. Use of the ornithine decarboxylase promoter to achieve N-MYC-mediated overexpression of a rabbit carboxylesterase to sensitize neuroblastoma cells to CPT-11. Mol Ther 2000; 1:457-63. [PMID: 10933967 DOI: 10.1006/mthe.2000.0064] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Overexpression of specific transcription factors by tumor cells can be exploited to regulate expression of proteins that induce apoptosis or activate prodrugs, thereby producing tumor-selective toxicity. A majority of advanced-stage neuroblastomas overexpress the transcription factor N-MYC, and this overexpression is associated with poor prognosis. This study describes regulation of expression by N-MYC, via the ornithine decarboxylase (ODC) promoter, of a rabbit liver carboxylesterase (CE) that activates the prodrug CPT-11. Chloramphenicol acetyltransferase reporter assays and CE activity assays in transiently transfected neuroblastoma cell lines (SJNB-1, SJNB-4, NB-1691) and rhabdomyosarcoma cell lines (JR1neo20, JR1Nmyc6, JR1Nmyc9) support this approach as a potential method for sensitizing tumor cells to CPT-11. Clonogenic assays with IMR32 human neuroblastoma cells which express N-MYC and that had been stably transfected with a plasmid containing an ODC promoter/CE cassette corroborated results of enzyme activity assays. Specifically, IMR32.ODC.CE cells expressed approximately eightfold more CE activity than IMR32.CMV.neo cells; and 5 microM CPT-11 reduced the clonogenic potential of IMR32.ODC.CE cells to zero, while 50 microM CPT-11 was required to produce the same effect with IMR32.CMV.neo cells. Current experiments focus on adenoviral delivery of an ODC promoter/CE cDNA cassette for potential virus-directed enzyme prodrug therapy applications.
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Mason SE, Bermanzohn PC, Siris SG. Clinical trials and tribulations: implementation processes in schizophrenia research outcome. Psychiatry 1998; 61:288-301. [PMID: 9919624 DOI: 10.1080/00332747.1998.11024841] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
This article focuses on an area in clinical drug trials for new antipsychotic medications for the treatment of schizophrenia which has not received sufficient attention in the literature: the day-to-day implementation tasks performed by research staff which have potential effects on study results. Implementation tasks are viewed as dynamic processes involving interactions among research and nonresearch staff, patients, families, and pharmaceutical company staff. Research-related demands and possible sources of stress for all participants in the process, such as recruiting and maintaining patients in studies, are discussed. Suggestions are offered for increasing the ease of participation. Further investigation is called for in several areas including variability in the effectiveness of research teams and in the rarely discussed interactions between site staff and pharmaceutical company personnel, as they may affect research outcomes. It is posited that increased knowledge about implementation processes in schizophrenia drug development is needed to more fully understand study results and to enhance patients' and their families' willingness to participate.
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Thompson WB, Mason SE. Instability of individual differences in the association between confidence judgments and memory performance. Mem Cognit 1996; 24:226-34. [PMID: 8881325 DOI: 10.3758/bf03200883] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
There are large individual differences in the degree of association between the accuracy of memories and subjective confidence in those memories. Are these differences stable within the same test, and between alternate forms of a test? In Experiment 1, college students were tested on 3 recognition memory tasks, then retested 2 weeks later on alternate forms of the same tasks. The relationship between confidence judgments and recognition performance displayed low split-half stability and low alternate-forms stability. A second experiment with elderly adults replicated these findings. In a third experiment, college students recalled answers to general knowledge questions and rated confidence in the correctness of each answer. Individual differences in the association between confidence and recall performance were not stable across the odd- and even-numbered items on the test. These data indicate the need for the development of procedures that will produce stable estimates of individuals' metacognitive accuracy.
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