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Liao Y, Pourzal R, Wimmer MA, Jacobs JJ, Fischer A, Marks LD. Graphitic tribological layers in metal-on-metal hip replacements. Science 2012; 334:1687-90. [PMID: 22194573 DOI: 10.1126/science.1213902] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Arthritis is a leading cause of disability, and when nonoperative methods have failed, a prosthetic implant is a cost-effective and clinically successful treatment. Metal-on-metal replacements are an attractive implant technology, a lower-wear alternative to metal-on-polyethylene devices. Relatively little is known about how sliding occurs in these implants, except that proteins play a critical role and that there is a tribological layer on the metal surface. We report evidence for graphitic material in the tribological layer in metal-on-metal hip replacements retrieved from patients. As graphite is a solid lubricant, its presence helps to explain why these components exhibit low wear and suggests methods of improving their performance; simultaneously, this raises the issue of the physiological effects of graphitic wear debris.
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Cherry KE, Brown JS, Marks LD, Galea S, Volaufova J, Lefante C, Su LJ, Welsh DA, Jazwinski SM. Longitudinal Assessment of Cognitive and Psychosocial Functioning After Hurricanes Katrina and Rita: Exploring Disaster Impact on Middle-Aged, Older, and Oldest-Old Adults. ACTA ACUST UNITED AC 2012; 16:187-211. [PMID: 23526570 DOI: 10.1111/j.1751-9861.2011.00073.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The authors examined the effects of Hurricanes Katrina and Rita (HKR) on cognitive and psychosocial functioning in a lifespan sample of adults 6 to 14 months after the storms. Participants were recruited from the Louisiana Healthy Aging Study (LHAS). Most were assessed during the immediate impact period and retested for this study. Analyses of pre-and post-disaster cognitive data confirmed that storm-related decrements in working memory for middle-aged and older adults observed in the immediate impact period had returned to pre-hurricane levels in the post-disaster recovery period. Middle-aged adults reported more storm-related stressors and greater levels of stress than the two older groups at both waves of testing. These results are consistent with a burden perspective on post-disaster psychological reactions.
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Ringe E, Van Duyne RP, Marks LD. Wulff construction for alloy nanoparticles. NANO LETTERS 2011; 11:3399-403. [PMID: 21744799 DOI: 10.1021/nl2018146] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The Wulff construction is an invaluable tool to understand and predict the shape of nanoparticles. We demonstrate here that this venerable model, which gives a size-independent thermodynamic shape, becomes size dependent in the nanoscale regime for an alloy and that the infinite reservoir approximation breaks down. The improvements in structure and energetic modeling have wide-ranging implications both in areas where energetics govern (e.g., nucleation and growth) and where the surface composition is important (e.g., heterogeneous catalysis).
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Tausch C, Marks LD, Brown JS, Cherry KE, Frias T, McWilliams Z, Melancon M, Sasser DD. Religion and Coping with Trauma: Qualitative Examples from Hurricanes Katrina and Rita. JOURNAL OF RELIGION SPIRITUALITY & AGING 2011; 23:236-253. [PMID: 23335865 DOI: 10.1080/15528030.2011.563203] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
In this article, we consider the intersection of religious coping and the experience of Hurricanes Katrina and Rita in a lifespan sample of adults living in South Louisiana during the 2005 storms. Participants were young, middle-age, older, and oldest-old adults who were interviewed during the post-disaster recovery period. Qualitative analyses confirmed that three dimensions of religion were represented across participants' responses. These dimensions included: 1) faith community, in relation to the significant relief effort and involvement of area churches; 2) religious practices, in the sense of participants' behavioral responses to the storms, such as prayer; and c) spiritual beliefs, referring to faith as a mechanism underlying individual and family-level adjustment, acceptance and personal growth in the post-disaster period. Implications for future disaster preparedness are considered.
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Kienzle DM, Becerra-Toledo AE, Marks LD. Vacant-site octahedral tilings on SrTiO(3) (001), the (sqrt[13]×sqrt[13])R33.7° surface, and related structures. PHYSICAL REVIEW LETTERS 2011; 106:176102. [PMID: 21635052 DOI: 10.1103/physrevlett.106.176102] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2011] [Indexed: 05/24/2023]
Abstract
The structure of the SrTiO(3) (001) (sqrt[13]×sqrt[13])R33.7° surface reconstruction has been determined using transmission electron diffraction combined with direct methods and density functional theory. It has a TiO(2)-rich surface with a 2D tiling of edge or corner-sharing TiO(5)□ octahedra. Additionally, different arrangements of these octahedral units at the surface, dictated by local bond-valence sums, form 2D networks that can account for many ordered surface reconstructions as well as disordered glasslike structures consistent with the multitude of structures observed experimentally, and potentially other materials and interfaces.
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Brown JS, Cherry KE, Marks LD, Jackson EM, Volaufova J, Lefante C, Jazwinski SM. After Hurricanes Katrina and Rita: gender differences in health and religiosity in middle-aged and older adults. Health Care Women Int 2010; 31:997-1012. [PMID: 20924874 PMCID: PMC3410670 DOI: 10.1080/07399332.2010.514085] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
We examined health-related quality of life in adults in the Louisiana Health Aging Study (LHAS) after Hurricanes Katrina and Rita (HK/R) that made landfall on the U.S. Gulf Coast region in 2005. Analyses of pre- and post-disaster SF-36 scores yielded changes in physical function and bodily pain. Mental health scores were lower for women than men. Gender differences were observed in religious beliefs and religious coping, favoring women. Religious beliefs and religious coping were negatively correlated with physical function, implying that stronger reliance on religiosity as a coping mechanism may be more likely among those who are less physically capable.
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Lambert NM, Fincham FD, Marks LD, Stillman TF. Invocations and intoxication: does prayer decrease alcohol consumption? PSYCHOLOGY OF ADDICTIVE BEHAVIORS 2010; 24:209-19. [PMID: 20565147 DOI: 10.1037/a0018746] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Four methodologically diverse studies (N = 1,758) show that prayer frequency and alcohol consumption are negatively related. In Study 1 (n = 824), we used a cross-sectional design and found that higher prayer frequency was related to lower alcohol consumption and problematic drinking behavior. Study 2 (n = 702) used a longitudinal design and found that more frequent prayer at Time 1 predicted less alcohol consumption and problematic drinking behavior at Time 2, and this relationship held when controlling for baseline levels of drinking and prayer. In Study 3 (n = 117), we used an experimental design to test for a causal relationship between prayer frequency and alcohol consumption. Participants assigned to pray every day (either an undirected prayer or a prayer for a relationship partner) for 4 weeks drank about half as much alcohol at the conclusion of the study as control participants. Study 4 (n = 115) replicated the findings of Study 3, as prayer again reduced drinking by about half. These findings are discussed in terms of prayer as reducing drinking motives.
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Marks LD. Prayer and Marital Intervention: Asking for Divine Help … or Professional Trouble? JOURNAL OF SOCIAL AND CLINICAL PSYCHOLOGY 2008. [DOI: 10.1521/jscp.2008.27.7.678] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Warschkow O, Wang Y, Subramanian A, Asta M, Marks LD. Structure and local-equilibrium thermodynamics of the c(2x2) reconstruction of rutile TiO2 (100). PHYSICAL REVIEW LETTERS 2008; 100:086102. [PMID: 18352638 DOI: 10.1103/physrevlett.100.086102] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2007] [Indexed: 05/26/2023]
Abstract
We resolve the structure of a c(2x2) reconstruction of the rutile TiO2 (100) surface using a combination of transmission electron diffraction, direct methods analysis, and density functional theory. The surface structure contains an ordered array of subsurface oxygen vacancies and is in local thermodynamic equilibrium with bulk TiO2, but not the with oxygen gas-phase environment. The transition into a bulklike (1x1) reconstruction offers insights into the time-dependent local thermodynamics of TiO2 surface reconstruction under global nonequilibrium conditions.
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Ciston J, Deng B, Marks LD, Own CS, Sinkler W. A quantitative analysis of the cone-angle dependence in precession electron diffraction. Ultramicroscopy 2007; 108:514-22. [PMID: 17854997 DOI: 10.1016/j.ultramic.2007.08.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2007] [Revised: 06/29/2007] [Accepted: 08/01/2007] [Indexed: 11/26/2022]
Abstract
Precession electron diffraction (PED) is a technique which is gaining increasing interest due to its ease of use and reduction of the dynamical scattering problem in electron diffraction. To further investigate the usefulness of this technique, we have performed a systematic study of the effect of precession angle on the mineral andalusite where the semiangle was varied from 6.5 to 32 mrad in five discrete steps. The purpose of this study was to determine the optimal conditions for the amelioration of kinematically forbidden reflections, and the measurement of valence charge density. We show that the intensities of kinematically forbidden reflections decay exponentially as the precession semiangle (varphi) is increased. We have also determined that charge density effects are best observed at moderately low angles (6.5-13 mrad) even though PED patterns become more kinematical in nature as the precession angle is increased further.
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Lanier CH, Rondinelli JM, Deng B, Kilaas R, Poeppelmeier KR, Marks LD. Surface Reconstruction with a Fractional Hole: (sqrt[5] x sqrt[5])R26.6 degrees LaAlO3 (001). PHYSICAL REVIEW LETTERS 2007; 98:086102. [PMID: 17359114 DOI: 10.1103/physrevlett.98.086102] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2006] [Indexed: 05/14/2023]
Abstract
The structure of the (sqrt[5] x sqrt[5])R26.6 degrees reconstruction of LaAlO3 (001) has been determined using transmission electron diffraction combined with direct methods. It has a lanthanum oxide termination with one lanthanum vacancy per surface unit cell. Density functional calculations indicate that charge compensation occurs by a fractional number of highly delocalized holes, and that the surface contains no oxygen vacancies and the holes are not filled with hydrogen. The reconstruction can be understood in terms of expulsion of the more electropositive cation from the surface and increased covalency.
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Own CS, Marks LD, Sinkler W. Precession electron diffraction 1: multislice simulation. Acta Crystallogr A 2006; 62:434-43. [PMID: 17057352 DOI: 10.1107/s0108767306032892] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2006] [Accepted: 08/17/2006] [Indexed: 11/10/2022] Open
Abstract
Precession electron diffraction (PED) is a method that considerably reduces dynamical effects in electron diffraction data, potentially enabling more straightforward solution of structures using the transmission electron microscope. This study focuses upon the characterization of PED data in an effort to improve the understanding of how experimental parameters affect it in order to predict favorable conditions. A method for generating simulated PED data by the multislice method is presented and tested. Data simulated for a wide range of experimental parameters are analyzed and compared to experimental data for the (Ga,In)(2)SnO(4) (GITO) and ZSM-5 zeolite (MFI) systems. Intensity deviations between normalized simulated and kinematical data sets, which are bipolar for dynamical diffraction data, become unipolar for PED data. Three-dimensional difference plots between PED and kinematical data sets show that PED data are most kinematical for small thicknesses, and as thickness increases deviations are minimized by increasing the precession cone semi-angle phi. Lorentz geometry and multibeam dynamical effects explain why the largest deviations cluster about the transmitted beam, and one-dimensional diffraction is pointed out as a strong mechanism for deviation along systematic rows. R factors for the experimental data sets are calculated, demonstrating that PED data are less sensitive to thickness variation. This error metric was also used to determine the experimental specimen thickness. R(1) (unrefined) was found to be about 12 and 15% for GITO and MFI, respectively.
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Deng B, Marks LD. Theoretical structure factors for selected oxides and their effects in high-resolution electron-microscope (HREM) images. Acta Crystallogr A 2006; 62:208-16. [PMID: 16614493 DOI: 10.1107/s010876730601004x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2005] [Accepted: 03/17/2006] [Indexed: 11/10/2022] Open
Abstract
A reasonably detailed analysis of the effects of charge redistribution on both X-ray and electron structure factors as well as for high-resolution electron-microscope images are presented for a series of light-element oxides. The charge redistribution leads to differences of 2-3% for the X-ray structure factors and 5-7% for electron structure factors in the 0-0.5 A(-1) region. There are detectable changes in images of about 10% of the contrast, somewhat dependent upon the alignment of atom columns, specimen thickness and defocus. These studies suggest that charge redistribution may be detectable using a Cc-limited aberration-corrected microscope with a specimen thickness of about 50 A.
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Garrison MEB, Marks LD, Lawrence FC, Braun B. Religious beliefs, faith community involvement and depression: a study of rural, low-income mothers. Women Health 2005; 40:51-62. [PMID: 15829445 DOI: 10.1300/j013v40n03_04] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The current study investigated the connection between religion and mental health of 131 rural, low-income mothers. Two dimensions of religion, beliefs and faith community involvement, were included and depression was assessed by the CES-D. The sample consisted of mothers who participated in Wave 2 of a multi-state research project. As hypothesized, both religious beliefs and faith community involvement were negatively related to depressive symptoms indicating that mothers with stronger religious beliefs and more involvement in religious activities may experience less depressive symptoms. The results of the current study confirm previous work and support a multifaceted view of religion.
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Own CS, Sinkler W, Marks LD. Rapid structure determination of a metal oxide from pseudo-kinematical electron diffraction data. Ultramicroscopy 2005; 106:114-22. [PMID: 16125847 DOI: 10.1016/j.ultramic.2005.06.058] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2005] [Revised: 06/13/2005] [Accepted: 06/22/2005] [Indexed: 12/01/2022]
Abstract
The electron precession diffraction technique is employed to provide quasi-kinematical data for determination of atom positions in the (Ga,In)2SnO5m-phase. Precession data are compared with conventional diffraction data captured under identical conditions and show a distinct superiority because they exhibit kinematical characteristics in the structure-defining reflections. Precessed data are not usable within a kinematical interpretation in all cases, and a simple basis is presented for omission of errant reflections to improve adherence to kinematical behavior. A second approach is demonstrated where intensities are used with direct methods instead of amplitudes, enhancing the contrast between strong and weak beams. The unrefined atom positions recovered a priori via direct methods are consistent between the two approaches and fall on average within 4 picometers of positions in the previously refined structure.
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Kilaas R, Marks LD, Own CS. EDM 1.0: Electron direct methods. Ultramicroscopy 2005; 102:233-7. [PMID: 15639355 DOI: 10.1016/j.ultramic.2004.10.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2004] [Revised: 09/30/2004] [Accepted: 10/12/2004] [Indexed: 11/24/2022]
Abstract
A computer program designed to provide a number of quantitative analysis tools for high-resolution imaging and electron diffraction data is described. The program includes basic image manipulation, both real space and reciprocal space image processing, Wiener-filtering, symmetry averaging, methods for quantification of electron diffraction patterns and two-dimensional direct methods. The program consists of a number of sub-programs written in a combination of C++, C and Fortran. It can be downloaded either as GNU source code or as binaries and has been compiled and verified on a wide range of platforms, both Unix based and PC's. Elements of the design philosophy as well as future possible extensions are described.
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Subramanian A, Marks LD, Warschkow O, Ellis DE. Direct observation of charge transfer at a MgO(111) surface. PHYSICAL REVIEW LETTERS 2004; 92:026101. [PMID: 14753947 DOI: 10.1103/physrevlett.92.026101] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2003] [Indexed: 05/24/2023]
Abstract
Transmission electron diffraction (TED) combined with direct methods have been used to study the sqrt[3]xsqrt[3]R30 degrees reconstruction on the polar (111) surface of MgO and refine the valence charge distribution. The surface is nonstoichiometric and is terminated by a single magnesium atom. A charge-compensating electron hole is localized in the next oxygen layer and there is a nominal charge transfer from the oxygen atoms to the top magnesium atom. The partial charges that we obtain for the surface atoms are in reasonable agreement with empirical bond-valence estimations.
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Subramanian A, Marks LD. Surface crystallography via electron microscopy. Ultramicroscopy 2004; 98:151-7. [PMID: 15046794 DOI: 10.1016/j.ultramic.2003.08.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2003] [Revised: 07/08/2003] [Indexed: 10/27/2022]
Abstract
The study of atomic structure of surfaces is fundamental to the understanding of electronic, chemical and mechanical properties of surfaces and numerous techniques have been developed to this end. Transmission Electron Microscopy techniques, namely transmission electron imaging (TEM) and diffraction (TED), due to their ability to provide structural information at very high resolutions, have emerged as powerful tools for the study of surface structure. In this article we review the experimental method alongside the various post-processing routines that are necessary to extract vital structural information from experimental data.
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Marks LD, Sinkler W. Sufficient conditions for Direct Methods with swift electrons. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2003; 9:399-410. [PMID: 19771696 DOI: 10.1017/s1431927603030332] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We investigate cases where one can argue that sufficient conditions exist for Direct Methods to work with swift electrons. In addition to simple cases where kinematical scattering holds (e.g., surfaces in plan view), we identify three other configurations: (a) when 1s channeling holds and kinematical scattering is statistically correct; (b) when there is a mapping from kinematical to dynamical intensities that preserves the order of the intensities, for instance with powder or precession data, and (c) when the scattering is dominated by one type of atom. We also briefly discuss the possibility of using Direct Methods to restore the complex exit wave leaving a sample in the most general case.
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Howells M, Marks LD, Miao J. Lensless imaging: a workshop on "new approaches to the phase problem for non-periodic objects.". Ultramicroscopy 2001; 90:1-6. [PMID: 11794624 DOI: 10.1016/s0304-3991(01)00128-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Over the past two decades, theoretical tools and algorithms have been developed which, under not very restrictive conditions, allow the reconstruction of images from diffraction patterns of non-periodic objects. These methods promise lensless imaging for any radiation, free of aberrations, with wavelength-limited resolution. Recent experimental successes prompted an interdisciplinary international workshop on this topic at the Lawrence Berkeley National Laboratory, Berkeley, CA, USA, on May 17-19 2001, supported by the DOE, LBL and the Advanced Light Source. Our aim was to review the field, and to stimulate communication between the Signal Recovery, Coherent Optics, X-ray, Electron Microscopy and Applied Mathematics communities. The results are summarized in this paper and on the web. A second workshop is planned for 2003.
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Chukhovskii FN, Hu JJ, Marks LD. Statistical dynamical direct methods. II. The three-phase structure invariant. Acta Crystallogr A 2001; 57:231-9. [PMID: 11326107 DOI: 10.1107/s0108767300015786] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2000] [Accepted: 10/31/2000] [Indexed: 11/10/2022] Open
Abstract
The triplet distribution used for kinematical diffraction is extended to the complex case appropriate for dynamical transmission electron diffraction. It is demonstrated that this gives good results if the distributions are handled statistically rather than relying upon single triplet relationships. As a consequence, conventional statistical direct methods will yield a reasonable approximation to the effective dynamical potential for thicknesses when kinematical theory is not appropriate. The recovered effective dynamical potential may be similar to the kinematical potential, but does not have to be and in general will not be.
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Kumpf C, Marks LD, Ellis D, Smilgies D, Landemark E, Nielsen M, Feidenhans'l R, Zegenhagen J, Bunk O, Zeysing JH, Su Y, Johnson RL. Subsurface dimerization in III-V semiconductor (001) surfaces. PHYSICAL REVIEW LETTERS 2001; 86:3586-3589. [PMID: 11328029 DOI: 10.1103/physrevlett.86.3586] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2000] [Revised: 01/17/2001] [Indexed: 05/23/2023]
Abstract
We present the atomic structure of the c(8 x 2) reconstructions of InSb-, InAs-, and GaAs-(001) surfaces as determined by surface x-ray diffraction using direct methods. Contrary to common belief, group III dimers are not prominent on the surface, instead subsurface dimerization of group III atoms takes place in the second bilayer, accompanied by a major rearrangement of the surface atoms above the dimers to form linear arrays. By varying the occupancies of four surface sites the (001)-c(8 x 2) reconstructions of III-V semiconductors can be described in a unified model.
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Bengu E, Marks LD. Single-walled BN nanostructures. PHYSICAL REVIEW LETTERS 2001; 86:2385-2387. [PMID: 11289935 DOI: 10.1103/physrevlett.86.2385] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2000] [Indexed: 05/23/2023]
Abstract
We describe in situ synthesis and characterization of single-walled BN nanotubes terminated by fullerenelike structures using electron-cyclotron resonance nitrogen and electron beam boron sources onto polycrystalline tungsten substrates. Detailed comparisons of experimental high-resolution electron microscopy images and simulations based upon molecular models show a dominance of kinks and bends involving fourfold and eightfold ring structures as against fivefold or sevenfold which have been found with carbon. Analysis of the structures as a function of film thickness indicates that they are growing by addition of atoms to the exposed ends of single sheets, not at the substrate-nanostructure interface.
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Gai PL, Boyes ED, Carter CB, Cockayne DJ, Marks LD, Pennycook SJ. Celebrations in Pioneering Electron Microscopy: A Symposium in Honor of Professor Archie Howie-Introduction. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2000; 6:281-284. [PMID: 10898809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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50
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Leslie C, Landree E, Collazo-Davila C, Bengu E, Grozea D, Marks LD. Electron crystallography in surface structure analysis. Microsc Res Tech 1999; 46:160-77. [PMID: 10420173 DOI: 10.1002/(sici)1097-0029(19990801)46:3<160::aid-jemt2>3.0.co;2-#] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Surface structure analysis is an important area of research, and in recent years notable advances have been made in this field, both in improved techniques for studying surfaces and in methods of analyzing them. This review aims to summarize the techniques available, particularly those relating to electron microscopy, and also to outline one of the newest areas of development, the application of direct methods to surface structure analysis.
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