Complex centers of polynomial differential equations

Directory of Open Access Journals (Sweden)

Mohamad Ali M. Alwash

2007-07-01

Full Text Available We present some results on the existence and nonexistence of centers for polynomial first order ordinary differential equations with complex coefficients. In particular, we show that binomial differential equations without linear terms do not have complex centers. Classes of polynomial differential equations, with more than two terms, are presented that do not have complex centers. We also study the relation between complex centers and the Pugh problem. An algorithm is described to solve the Pugh problem for equations without complex centers. The method of proof involves phase plane analysis of the polar equations and a local study of periodic solutions.

Electrical studies of Fe-related defect complexes in silicon

Energy Technology Data Exchange (ETDEWEB)

Tang, Chi Kwong

2012-09-15

Iron (Fe) is an important impurity in solar-grade silicon which contributes substantially in degrading the efficiency of solar cells. The degradation is mainly caused by the Fe atoms situating at an unperturbed tetrahedral interstitial sites (Fei) in the silicon crystal, consequently acting as a recombination center. By altering the position and the neighbouring environment at which the Fe atoms reside, there are opportunities in minimizing or neutralizing the electrical activity of Fe. Furthermore, utilizing the high mobility of Fe, one can increase the performance of a device by accumulating the Fe atoms from critical regions into regions where Fe can be tolerated. These approaches can help in realizing high efficient solar cells based on cheap and highly Fe-contaminated silicon. In this work, we have investigated the interaction between Fe and defects relevant to solar cells, using mainly electrical characterization methods such as capacitance-voltage measurement, deep level transient spectroscopy and admittance spectroscopy. From the study of potential hydrogen passivation of Fe, hydrogen was introduced through wet chemical etching and further driven to a defined region. Using depth profiles, it is found that incorporation of hydrogen stimulates the dissociation of the iron-boron (Fe-B) pair, releasing and resulting in the unwanted Fei. At the same time, no passivation of Fe by hydrogen has been observed. On the investigation of the mechanism of phosphorus gettering of metal impurities, vacancies have been generated through proton-irradiation. The resulting irradiation-induced defects were examined for reactions with Fe after heat treatments. Based on the evolution of defect concentrations by isochronal annealings, it is found that Fe interacts with the divacancy and the vacancy-oxygen complexes, forming deep levels of 0.28 eV and 0.34 eV above the valence band edge (EV), respectively. In the search for substitutional Fe to investigate its electrical activity

Revitalizing Complex Analysis: A Transition-to-Proof Course Centered on Complex Topics

Science.gov (United States)

Sachs, Robert

2017-01-01

A new transition course centered on complex topics would help in revitalizing complex analysis in two ways: first, provide early exposure to complex functions, sparking greater interest in the complex analysis course; second, create extra time in the complex analysis course by eliminating the "complex precalculus" part of the course. In…

Selection and Characterization of Palmitic Acid Responsive Patients with an OXPHOS Complex I Defect

Directory of Open Access Journals (Sweden)

Tom E. J. Theunissen

2017-10-01

Full Text Available Mitochondrial disorders are genetically and clinically heterogeneous, mainly affecting high energy-demanding organs due to impaired oxidative phosphorylation (OXPHOS. Currently, effective treatments for OXPHOS defects, with complex I deficiency being the most prevalent, are not available. Yet, clinical practice has shown that some complex I deficient patients benefit from a high-fat or ketogenic diet, but it is unclear how these therapeutic diets influence mitochondrial function and more importantly, which complex I patients could benefit from such treatment. Dietary studies in a complex I deficient patient with exercise intolerance showed increased muscle endurance on a high-fat diet compared to a high-carbohydrate diet. We performed whole-exome sequencing to characterize the genetic defect. A pathogenic homozygous p.G212V missense mutation was identified in the TMEM126B gene, encoding an early assembly factor of complex I. A complementation study in fibroblasts confirmed that the p.G212V mutation caused the complex I deficiency. The mechanism turned out to be an incomplete assembly of the peripheral arm of complex I, leading to a decrease in the amount of mature complex I. The patient clinically improved on a high-fat diet, which was supported by the 25% increase in maximal OXPHOS capacity in TMEM126B defective fibroblast by the saturated fatty acid palmitic acid, whereas oleic acid did not have any effect in those fibroblasts. Fibroblasts of other patients with a characterized complex I gene defect were tested in the same way. Patient fibroblasts with complex I defects in NDUFS7 and NDUFAF5 responded to palmitic acid, whereas ACAD9, NDUFA12, and NDUFV2 defects were non-responding. Although the data are too limited to draw a definite conclusion on the mechanism, there is a tendency that protein defects involved in early assembly complexes, improve with palmitic acid, whereas proteins defects involved in late assembly, do not. Our data show at

Hydrogen interaction with radiation defects in p-type silicon

CERN Document Server

Feklisova, O V; Yakimov, E B; Weber, J

2001-01-01

Hydrogen interaction with radiation defects in p-type silicon has been investigated by deep-level non-stationary spectroscopy. Hydrogen is introduced into the high-energy electron-irradiated crystals under chemical etching in acid solutions at room temperature followed by the reverse-bias annealing at 380 K. It is observed that passivation of the irradiation-induced defects is accompanied by formation of novel electrically active defects with hydrogen-related profiles. Effect of hydrogen on the electrical activity of the C sub s C sub i complexes is shown for the first time. Based on the spatial distribution and passivation kinetics, possible nature of the novel complexes is analyzed. The radii for hydrogen capture by vacancies, K-centers, C sub s C sub i centers and the novel complexes are determined

Defect complexes in carbon and boron nitride nanotubes

CSIR Research Space (South Africa)

Mashapa, MG

2012-05-01

Full Text Available The effect of defect complexes on the stability, structural and electronic properties of single-walled carbon nanotubes and boron nitride nanotubes is investigated using the ab initio pseudopotential density functional method implemented...

Controlled coupling of NV defect centers to plasmonic and photonic nanostructures

Energy Technology Data Exchange (ETDEWEB)

Barth, Michael, E-mail: michael.barth@physik.hu-berlin.d [Institute of Physics, Humboldt-Universitaet zu Berlin, Hausvogteiplatz 5-7, D-10117 Berlin (Germany); Schietinger, Stefan; Schroeder, Tim; Aichele, Thomas; Benson, Oliver [Institute of Physics, Humboldt-Universitaet zu Berlin, Hausvogteiplatz 5-7, D-10117 Berlin (Germany)

2010-09-15

Nitrogen-vacancy (NV) defect centers in diamond have recently emerged as promising candidates for a number of applications in the fields of quantum optics and quantum information, such as single photon generation and spin qubit operations. The performance of these defect centers can strongly be enhanced through coupling to plasmonic and photonic nanostructures, such as metal particles and optical microcavities. Here, we demonstrate the controlled assembly of such hybrid structures via manipulation with scanning near-field probes. In particular, we investigate the plasmonic enhancement of the single photon emission through coupling to gold nanospheres as well as the coupling of diamond nanocrystals to the optical modes of microsphere resonators and photonic crystal cavities. These systems represent prototypes of fundamental nanophotonic/plasmonic elements and provide control on the generation and coherent transfer of photons on the level of a single quantum emitter.

Rapid screening for nuclear genes mutations in isolated respiratory chain complex I defects.

Science.gov (United States)

Pagniez-Mammeri, Hélène; Lombes, Anne; Brivet, Michèle; Ogier-de Baulny, Hélène; Landrieu, Pierre; Legrand, Alain; Slama, Abdelhamid

2009-04-01

Complex I or reduced nicotinamide adenine dinucleotide (NADH): ubiquinone oxydoreductase deficiency is the most common cause of respiratory chain defects. Molecular bases of complex I deficiencies are rarely identified because of the dual genetic origin of this multi-enzymatic complex (nuclear DNA and mitochondrial DNA) and the lack of phenotype-genotype correlation. We used a rapid method to screen patients with isolated complex I deficiencies for nuclear genes mutations by Surveyor nuclease digestion of cDNAs. Eight complex I nuclear genes, among the most frequently mutated (NDUFS1, NDUFS2, NDUFS3, NDUFS4, NDUFS7, NDUFS8, NDUFV1 and NDUFV2), were studied in 22 cDNA fragments spanning their coding sequences in 8 patients with a biochemically proved complex I deficiency. Single nucleotide polymorphisms and missense mutations were detected in 18.7% of the cDNA fragments by Surveyor nuclease treatment. Molecular defects were detected in 3 patients. Surveyor nuclease screening is a reliable method for genotyping nuclear complex I deficiencies, easy to interpret, and limits the number of sequence reactions. Its use will enhance the possibility of prenatal diagnosis and help us for a better understanding of complex I molecular defects.

Defect-impurity complex induced long-range ferromagnetism in GaN nanowires

KAUST Repository

Assa Aravindh, S

2015-12-14

Present work investigates the structural, electronic and magnetic properties of Gd doped wurtzite GaN nanowires (NWs) oriented along the [0001] direction in presence of intrinsic defects by employing the GGA + U approximation. We find that Ga vacancy (VGa) exhibits lower formation energy compared to N vacancy. Further stabilization of point defects occurs due to the presence of Gd. The strength of ferromagnetism (FM) increases by additional positive charge induced by the VGa. Electronic structure analysis shows that VGa introduces defect levels in the band gap leading to ferromagnetic coupling due to the hybridization of the p states of the Ga and N atoms with the Gd d and f states. Ferromagnetic exchange coupling energy of 76.4 meV is obtained in presence of Gd-VGa complex; hence, the FM is largely determined by the cation vacancy-rare earth complex defects in GaN NWs.

Defect-impurity complex induced long-range ferromagnetism in GaN nanowires

KAUST Repository

Assa Aravindh, S; Roqan, Iman S.

2015-01-01

Present work investigates the structural, electronic and magnetic properties of Gd doped wurtzite GaN nanowires (NWs) oriented along the [0001] direction in presence of intrinsic defects by employing the GGA + U approximation. We find that Ga vacancy (VGa) exhibits lower formation energy compared to N vacancy. Further stabilization of point defects occurs due to the presence of Gd. The strength of ferromagnetism (FM) increases by additional positive charge induced by the VGa. Electronic structure analysis shows that VGa introduces defect levels in the band gap leading to ferromagnetic coupling due to the hybridization of the p states of the Ga and N atoms with the Gd d and f states. Ferromagnetic exchange coupling energy of 76.4 meV is obtained in presence of Gd-VGa complex; hence, the FM is largely determined by the cation vacancy-rare earth complex defects in GaN NWs.

Ab initio study of metastability of Eu{sup 3+} defect complexes in GaN

Energy Technology Data Exchange (ETDEWEB)

Ouma, Cecil N.M., E-mail: Cecil.Ouma@up.ac.za; Meyer, Walter E.

2014-04-15

Density functional theory (DFT) within the generalized gradient approximation (GGA) has been used to study the structural and electronic properties of Eu{sup 3+} defect complexes in GaN under Ga-rich conditions. Two distinct configurations of the Eu{sub Ga}V{sub N} defect complex, the axial and basal configuration, have been investigated. We report two forms of metastable defects namely; the Negative U defect in the lower half of the GaN band-gap and a metastable defect with two distinct configurations each with levels at E{sub C} −0.46 eV and −0.56 eV in the upper half of the GaN band-gap.

Energetics and Defect Interactions of Complex Oxides for Energy Applications

Science.gov (United States)

Solomon, Jonathan Michael

The goal of this dissertation is to employ computational methods to gain greater insights into the energetics and defect interactions of complex oxides that are relevant for today's energy challenges. To achieve this goal, the development of novel computational methodologies are required to handle complex systems, including systems containing nearly 650 ions and systems with tens of thousands of possible atomic configurations. The systems that are investigated in this dissertation are aliovalently doped lanthanum orthophosphate (LaPO4) due to its potential application as a proton conducting electrolyte for intermediate temperature fuel cells, and aliovalently doped uranium dioxide (UO2) due to its importance in nuclear fuel performance and disposal. First we undertake density-functional-theory (DFT) calculations on the relative energetics of pyrophosphate defects and protons in LaPO4, including their binding with divalent dopant cations. In particular, for supercell calculations with 1.85 mol% Sr doping, we investigate the dopant-binding energies for pyrophosphate defects to be 0.37 eV, which is comparable to the value of 0.34 eV calculated for proton-dopant binding energies in the same system. These results establish that dopant-defect interactions further stabilize proton incorporation, with the hydration enthalpies when the dopants are nearest and furthest from the protons and pyrophosphate defects being -1.66 eV and -1.37 eV, respectively. Even though our calculations show that dopant binding enhances the enthalpic favorability of proton incorporation, they also suggest that such binding is likely to substantially lower the kinetic rate of hydrolysis of pyrophosphate defects. We then shift our focus to solid solutions of fluorite-structured UO 2 with trivalent rare earth fission product cations (M3+=Y, La) using a combination of ionic pair potential and DFT based methods. Calculated enthalpies of formation with respect to constituent oxides show higher

Laparoscopic omentoplasty to support anastomotic urethroplasty in complex and redo pelvic fracture urethral defects.

Science.gov (United States)

Kulkarni, Sanjay B; Barbagli, Guido; Joshi, Pankaj M; Hunter, Craig; Shahrour, Walid; Kulkarni, Jyotsna; Sansalone, Salvatore; Lazzeri, Massimo

2015-05-01

To test the hypothesis that a new surgical technique using elaborated perineal anastomotic urethroplasty combined with laparoscopic omentoplasty for patients with complex and prior failed pelvic fracture urethral defect repair was feasible, safe, and effective. We performed a prospective, observational, stage 2a study to observe treatment outcomes of combined perineal and laparoscopic approach for urethroplasty in patients with pelvic fracture urethral defect at a single center in Pune, India, between January 2012 and February 2013. Complex and redo patients with pelvic fracture urethral defect occurring after pelvic fracture urethral injury were included in the study. Anterior urethral strictures were excluded. The primary study outcome was the success rate of the surgical technique, and the secondary outcome was to evaluate feasibility and safety of the procedure. The clinical outcome was considered a failure when any postoperative instrumentation was needed. Fifteen male patients with a median age of 19 years were included in the study. Seven patients were adolescents (12-18 years) and 8 patients (53.3%) were adults (19-49 years). The mean number of prior urethroplasties was 1.8 (range, 1-3). All patients underwent elaborated bulbomembranous anastomosis using a perineal approach with inferior pubectomy combined with laparoscopic mobilization of the omentum into the perineum to envelope the anastomosis and to fill the perineal dead space. Of 15 patients, 14 (93.3%) were successful and 1 (6.6%) failed. One adolescent boy 14 years old developed a recurrent stricture 2 months after the procedure and was managed using internal urethrotomy. Median follow-up was 18 months (range, 13-24 months). Combining a laparoscopic omentoplasty to a membranobulbar anastomosis for complex and redo pelvic fracture urethral injury is successful, feasible, safe, and with minimal additional morbidity to the patient. The technique has the advantage of a perineal incision and the ability

Investigation of the chlorine A-Center in polycrystalline CdTe layers by photoluminescence spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Kraft, Christian; Metzner, Heiner; Haedrich, Mathias [Institut fuer Festkoerperphysik, Universitaet Jena, Max-Wien-Platz 1, 07743 Jena (Germany); Schley, Pascal [Institut fuer Physik, Technische Universitaet Ilmenau, 98684 Ilmenau (Germany); Goldhahn, Ruediger [Institut fuer Experimentelle Physik, Universitaet Magdeburg, 39016 Magdeburg (Germany)

2012-07-01

Polycrystalline CdTe is a well known absorber material for thin film solar cells. However, the improvement of CdTe-based solar cells for industrial application is mainly based on empirical enhancements of certain process steps which are not concerning the absorber itself. Hence, the defect structure of CdTe is still not understood in detail. One of the most discussed defects in CdTe is the so called chlorine A-center. In general, the A-Center describes a defect complex of the intrinsic cadmium vacancy defect and an extrinsic impurity. By means of photoluminescence spectroscopy at temperatures of 5 K we investigated the behavior of the chlorine A-center under different CdTe activation techniques. Therefore, we were able to determine the electronic level of that defect and to analyze its influence on the crystal quality and the functionality of solar cells that were prepared of the corresponding samples.

Study of new complexes of uranium and comba radical. I.- Complexes defective in sodium carbonate

International Nuclear Information System (INIS)

Vera Palomino, J.; Galiano Sedano, J. A.; Parellada Bellod, R.; Bellido Gonzalez, A.

1975-01-01

Some complexes formed in presence of defect of sodium carbonate with respect to the stoichiometric ratio (U): (C0 3 ) = 1:3 are studied. This ratio corresponds to the main complex which is responsible for the uranium extraction with CDMBAC organic solutions and from U(VI) aqueous solutions with an excess of sodium carbonate. (Author) 10 refs

Phenotypic Spectrum in Osteogenesis Imperfecta Due to Mutations in TMEM38B: Unraveling a Complex Cellular Defect.

Science.gov (United States)

Webb, Emma A; Balasubramanian, Meena; Fratzl-Zelman, Nadja; Cabral, Wayne A; Titheradge, Hannah; Alsaedi, Atif; Saraff, Vrinda; Vogt, Julie; Cole, Trevor; Stewart, Susan; Crabtree, Nicola J; Sargent, Brandi M; Gamsjaeger, Sonja; Paschalis, Eleftherios P; Roschger, Paul; Klaushofer, Klaus; Shaw, Nick J; Marini, Joan C; Högler, Wolfgang

2017-06-01

Recessive mutations in TMEM38B cause type XIV osteogenesis imperfecta (OI) by dysregulating intracellular calcium flux. Clinical and bone material phenotype description and osteoblast differentiation studies. Natural history study in pediatric research centers. Eight patients with type XIV OI. Clinical examinations included bone mineral density, radiographs, echocardiography, and muscle biopsy. Bone biopsy samples (n = 3) were analyzed using histomorphometry, quantitative backscattered electron microscopy, and Raman microspectroscopy. Cellular differentiation studies were performed on proband and control osteoblasts and normal murine osteoclasts. Type XIV OI clinical phenotype ranges from asymptomatic to severe. Previously unreported features include vertebral fractures, periosteal cloaking, coxa vara, and extraskeletal features (muscular hypotonia, cardiac abnormalities). Proband lumbar spine bone density z score was reduced [median -3.3 (range -4.77 to +0.1; n = 7)] and increased by +1.7 (1.17 to 3.0; n = 3) following bisphosphonate therapy. TMEM38B mutant bone has reduced trabecular bone volume, osteoblast, and particularly osteoclast numbers, with >80% reduction in bone resorption. Bone matrix mineralization is normal and nanoporosity low. We demonstrate a complex osteoblast differentiation defect with decreased expression of early markers and increased expression of late and mineralization-related markers. Predominance of trimeric intracellular cation channel type B over type A expression in murine osteoclasts supports an intrinsic osteoclast defect underlying low bone turnover. OI type XIV has a bone histology, matrix mineralization, and osteoblast differentiation pattern that is distinct from OI with collagen defects. Probands are responsive to bisphosphonates and some show muscular and cardiovascular features possibly related to intracellular calcium flux abnormalities. Copyright © 2017 Endocrine Society

Defect complexes and thermoluminescence in lithium fluoride. [X radiation

Energy Technology Data Exchange (ETDEWEB)

McKeever, S.W.S. (Oklahoma State Univ., Stillwater (USA). Dept. of Physics)

1984-01-01

X-ray induced luminescence measurements indicate that the emission wavelength is dependent upon the aggregation state of Mg within the LiF lattice. This suggests a close association between Mg and Ti within a defect complex. Pulse annealing measurements indicate that peak 5 may be due to the dissociation of trimers, followed by charge release.

Using the Dual-Tree Complex Wavelet Transform for Improved Fabric Defect Detection

Directory of Open Access Journals (Sweden)

Hermanus Vermaak

2016-01-01

Full Text Available The dual-tree complex wavelet transform (DTCWT solves the problems of shift variance and low directional selectivity in two and higher dimensions found with the commonly used discrete wavelet transform (DWT. It has been proposed for applications such as texture classification and content-based image retrieval. In this paper, the performance of the dual-tree complex wavelet transform for fabric defect detection is evaluated. As experimental samples, the fabric images from TILDA, a textile texture database from the Workgroup on Texture Analysis of the German Research Council (DFG, are used. The mean energies of real and imaginary parts of complex wavelet coefficients taken separately are identified as effective features for the purpose of fabric defect detection. Then it is shown that the use of the dual-tree complex wavelet transform yields greater performance as compared to the undecimated wavelet transform (UDWT with a detection rate of 4.5% to 15.8% higher depending on the fabric type.

New fundamental defects in a-SiO2

International Nuclear Information System (INIS)

Karna, S.P.; Kurtz, H.A.; Shedd, W.M.; Pugh, R.D.; Singaraju, B.K.

1999-01-01

Throughout the three decades of research into radiation-induced degradation of metal-oxide-semiconductor (MOS) devices, investigators understood that point defects in the Si-SiO 2 structure (localized deviations from stoichiometrically pure Si and SiO 2 ) are responsible for many observed anomalies. Basic research in this area has progressed along two tracks: (i) differentiating the anomalies based upon subtle differences in their characteristic behavior, and (ii) precise description of the defects responsible for the anomalous behavior. These two research tracks are complementary since often a discovery in one area provides insight and ultimately leads to discoveries in the other. Here, the atomic structure and spin properties of two previously undescribed amorphous silicon dioxide fundamental point defects have been characterized for the first time by ab initio quantum mechanical calculations. Both defects are electrically neutral trivalent silicon centers in the oxide. One of the defects, the X-center, is determined to have an O 2 Sitriple b ondSi ↑ atomic structure. The other defect, called the Y-center, is found to have an OSi 2 triple b ondSi ↑ structure. Calculated electronic and electrical properties of the new defect centers are consistent with the published characteristics of the oxide switching trap or border trap precursors

Radiation defects in lithium fluoride induced by heavy ions

Energy Technology Data Exchange (ETDEWEB)

Trautmann, C.; Schwartz, K.; Steckenreiter, T. [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Costantini, J.M. [CEA Centre d`Etudes de Bruyeres-le-Chatel, 91 (France). DPTA/SPMC; Toulemonde, M. [Centre Interdisciplinaire de Recherches avec les Ions Lourds (CIRIL), 14 - Caen (France)

1998-07-01

Single crystals of lithium fluoride were irradiated with various species of heavy ions in the energy regime between 1 and 30 MeV/u. The induced radiation damage was studied with techniques such as optical absorption spectroscopy, small-angle x-ray scattering, chemical etching and profilometry, complemented by annealing experiments. Clear evidence is given for a complex track structure and defect morphology. Single defects such as F-centers are produced in a large halo of several tens of nanometers around the ion trajectory. The defect creation in this zone is similar to that under conventional radiation. For heavy ions above a critical energy loss of 10 keV/nm, new effects occur within a very small core region of 2-4 nm in diameter. The damage in this zone is responsible for chemical etching and for a characteristic anisotropic x-ray scattering. It is assumed that in this core, complex defect aggregates (e.g., cluster of color centers, molecular anions and vacancies) are created. Their formation is only slightly influenced by the irradiation temperature and takes place even at 15 K where diffusion processes of primary defects are frozen. Furthermore, irradiation with heavy ions leads to pronounced swelling effects which can be related to an intermediate zone of around 10 nm around the ion path. (orig.) 40 refs.

Effect of the defect-phosphorus atom complex interaction on the formation of the properties of neutron-doped silicon

International Nuclear Information System (INIS)

Kolesnik, L.I.; Lejferov, B.M.

1984-01-01

Radiation-induced defect annealing and changes in the concentration of substituting phosphorus atoms in silicon irradiated with different neutron doses have been studied by the low-temperature photoluminescence (PL) method at 4 K. Based on the PL spectrum character dependence on the fast-to-thermal neutron ration in a flux, series of lines and bands associated with the preferential formation of radiation-induced defects (within the 1.100 eV energy range) and with the presence of phosphorus impurity (1.15-1.12 eV) are identified. Some peculiarities are studied of the stage-by-stage annealing (250-500, 430-600, 600-800 deg C) of recombination-active centers (RAC) determining the radiation in the mentioned spectrum region. The relation between the RAC variations within the 1.12-1.15 eV range and the substituting phosphorus atom concentration in the 400-500 deg C temperature range is found. Activation energy of the substituting phosphorus atom concentration variation is estimated (approximately 0.5 eV). It is shown that the formation of defect-phosphorus complexes plays an important role in the formation of neutron-doped silicon properties, the presence of fast neutron in a flux being most importants

Influence of neutrophil defects on Burkholderia cepacia complex pathogenesis

Directory of Open Access Journals (Sweden)

Laura A. Porter

2011-11-01

Full Text Available The Burkholderia cepacia complex (Bcc is a group of Gram-negative bacteria that are ubiquitous in the environment and have emerged as opportunistic pathogens in immunocompromised patients. The primary patient populations infected with Bcc include individuals with cystic fibrosis (CF, as well as those with chronic granulomatous disease (CGD. While Bcc infection in CF is better characterized than in CGD, these two genetic diseases are not obviously similar and it is currently unknown if there is any commonality in host immune defects that is responsible for the susceptibility to Bcc. CF is caused by mutations in the CF transmembrane conductance regulator, resulting in manifestations in various organ systems, however the major cause of morbidity and mortality is currently due to bacterial respiratory infections. CGD, on the other hand, is a genetic disorder that is caused by defects in phagocyte NADPH oxidase. Because of the defect in CGD, phagocytes in these patients are unable to produce reactive oxygen species, which results in increased susceptibility to bacterial and fungal infections. Despite this significant defect in microbial clearance, the spectrum of pathogens frequently implicated in infections in CGD is relatively narrow and includes some bacterial species that are considered almost pathognomonic for this disorder. Very little is known about the cause of the specific susceptibility to Bcc over other potential pathogens more prevalent in the environment, and a better understanding of specific mechanisms required for bacterial virulence has become a high priority. This review will summarize both the current knowledge and future directions related to Bcc virulence in immunocompromised individuals with a focus on the roles of bacterial factors and neutrophil defects in pathogenesis.

Argon defect complexes in low energy Ar irradiated molybdenum

International Nuclear Information System (INIS)

Veen, A. van; Buters, W.T.M.; Kolk, G.J. van der; Caspers, L.M.; Armstrong, T.R.

1982-01-01

Thermal desorption spectrometry has been used to study the defects created in Mo irradiated along the direction with Ar ions ranging in energy from 0.1 to 2 keV. In addition to monitoring the release of the implanted Ar, additional information has been obtained by decoration of the defects with low energy helium and subsequent monitoring of the helium release. The studies show evidence that the Ar can be trapped in both substitutional sites and in a configuration in which the Ar is associated with vacancies (ArVsub(n), n >= 2). Most of the Ar implanted at high energy is released at approx. equal to 1500 K by thermal vacancy assisted diffusion. Argon trapped closer to the surface is released at lower temperatures via at least three different surface related release mechanisms. Additional results are presented on the interaction of self interstitial atoms (introduced by 100 eV Xe bombardment) with the Ar defects. Substitutional Ar is found to convert to interstitial Ar which seems to be mobile at room temperature. The Ar-vacancy complexes are found to be reduced to substitutional Ar. The results of atomistic calculations of the release mechanisms will also be presented. (orig.)

Stabilization of primary mobile radiation defects in MgF{sub 2} crystals

Energy Technology Data Exchange (ETDEWEB)

Lisitsyn, V.M. [National Research Tomsk Polytechnic University, pr. Lenina 30, Tomsk 634050 (Russian Federation); Lisitsyna, L.A. [State University of Architecture and Building, pl. Solyanaya 2, Tomsk 634003 (Russian Federation); Popov, A.I., E-mail: popov@ill.fr [Institute of Solid State Physics, University of Latvia, 8 Kengaraga Str., LV-1063 Riga (Latvia); Kotomin, E.A. [Institute of Solid State Physics, University of Latvia, 8 Kengaraga Str., LV-1063 Riga (Latvia); Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart (Germany); Abuova, F.U.; Akilbekov, A. [L.N. Gumilyov Eurasian National University, 3 Munaitpasova Str., Astana (Kazakhstan); Maier, J. [Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart (Germany)

2016-05-01

Non-radiative decay of the electronic excitations (excitons) into point defects (F–H pairs of Frenkel defects) is main radiation damage mechanism in many ionic (halide) solids. Typical time scale of the relaxation of the electronic excitation into a primary, short-lived defect pair is about 1–50 ps with the quantum yield up to 0.2–0.8. However, only a small fraction of these primary defects are spatially separated and survive after transformation into stable, long-lived defects. The survival probability (or stable defect accumulation efficiency) can differ by orders of magnitude, dependent on the material type; e.g. ∼10% in alkali halides with f.c.c. or b.c.c. structure, 0.1% in rutile MgF{sub 2} and <0.001% in fluorides MeF{sub 2} (Me: Ca, Sr, Ba). The key factor determining accumulation of stable radiation defects is stabilization of primary defects, first of all, highly mobile hole H centers, through their transformation into more complex immobile defects. In this talk, we present the results of theoretical calculations of the migration energies of the F and H centers in poorely studied MgF{sub 2} crystals with a focus on the H center stabilization in the form of the interstitial F{sub 2} molecules which is supported by presented experimental data.

Preoperative Botulinum toxin A enabling defect closure and laparoscopic repair of complex ventral hernia.

Science.gov (United States)

Rodriguez-Acevedo, Omar; Elstner, Kristen E; Jacombs, Anita S W; Read, John W; Martins, Rodrigo Tomazini; Arduini, Fernando; Wehrhahm, Michael; Craft, Colette; Cosman, Peter H; Dardano, Anthony N; Ibrahim, Nabeel

2018-02-01

Operative management of complex ventral hernia still remains a significant challenge for surgeons. Closure of large defects in the unprepared abdomen has serious pathophysiological consequences due to chronic contraction and retraction of the lateral abdominal wall muscles. We report outcomes of 56 consecutive patients who had preoperative Botulinum toxin A (BTA) abdominal wall relaxation facilitating closure and repair. This was a prospective observational study of 56 patients who underwent ultrasound-guided BTA into the lateral abdominal oblique muscles prior to elective ventral hernia repair between November 2012 and January 2017. Serial non-contrast abdominal CT imaging was performed to evaluate changes in lateral oblique muscle length and thickness. All hernias were repaired laparoscopically, or laparoscopic-open-laparoscopic (LOL) using intraperitoneal onlay mesh. 56 patients received BTA injections at predetermined sites to the lateral oblique muscles, which were well tolerated. Mean patient age was 59.7 years, and mean BMI was 30.9 kg/m 2 (range 21.8-54.0). Maximum defect size was 24 × 27 cm. A subset of 18 patients underwent preoperative pneumoperitoneum as an adjunct procedure. A comparison of pre-BTA to post-BTA imaging demonstrated an increase in mean lateral abdominal wall length from 16.1 cm to 20.1 cm per side, a mean gain of 4.0 cm/side (range 1.0-11.7 cm/side) (p LOL primary closure was achieved in all cases, with no clinical evidence of raised intra-abdominal pressures. One patient presented with a new fascial defect 26 months post-operative. Preoperative BTA to the lateral abdominal wall muscles is a safe and effective technique for the preparation of patients prior to operative management of complex ventral hernias. BTA temporary flaccid paralysis relaxes, elongates and thins the chronically contracted abdominal musculature. This in turn reduces lateral traction forces facilitating laparoscopic repair and fascial closure of large

Semiconductor color-center structure and excitation spectra: Equation-of-motion coupled-cluster description of vacancy and transition-metal defect photoluminescence

Science.gov (United States)

Lutz, Jesse J.; Duan, Xiaofeng F.; Burggraf, Larry W.

2018-03-01

Valence excitation spectra are computed for deep-center silicon-vacancy defects in 3C, 4H, and 6H silicon carbide (SiC), and comparisons are made with literature photoluminescence measurements. Optimizations of nuclear geometries surrounding the defect centers are performed within a Gaussian basis-set framework using many-body perturbation theory or density functional theory (DFT) methods, with computational expenses minimized by a QM/MM technique called SIMOMM. Vertical excitation energies are subsequently obtained by applying excitation-energy, electron-attached, and ionized equation-of-motion coupled-cluster (EOMCC) methods, where appropriate, as well as time-dependent (TD) DFT, to small models including only a few atoms adjacent to the defect center. We consider the relative quality of various EOMCC and TD-DFT methods for (i) energy-ordering potential ground states differing incrementally in charge and multiplicity, (ii) accurately reproducing experimentally measured photoluminescence peaks, and (iii) energy-ordering defects of different types occurring within a given polytype. The extensibility of this approach to transition-metal defects is also tested by applying it to silicon-substituted chromium defects in SiC and comparing with measurements. It is demonstrated that, when used in conjunction with SIMOMM-optimized geometries, EOMCC-based methods can provide a reliable prediction of the ground-state charge and multiplicity, while also giving a quantitative description of the photoluminescence spectra, accurate to within 0.1 eV of measurement for all cases considered.

In-Situ Photoexcitation-Induced Suppression of Point Defect Generation in Ion Implanted Silicon

International Nuclear Information System (INIS)

Cho, C.R.; Rozgonyi, G.A.; Yarykin, N.; Zuhr, R.A.

1999-01-01

The formation of vacancy-related defects in n-type silicon has been studied immediately after implantation of He, Si, or Ge ions at 85 K using in-situ DLTS. A-center concentrations in He-implanted samples reach a maximum immediately after implantation, whereas, with Si or Ge ion implanted samples they continuously increase during subsequent anneals. It is proposed that defect clusters, which emit vacancies during anneals, are generated in the collision cascades of Si or Ge ions. An illumination-induced suppression of A-center formation is seen immediately after implantation of He ions at 85 K. This effect is also observed with Si or Ge ions, but only after annealing. The suppression of vacancy complex formation via photoexcitation is believed to occur due to an enhanced recombination of defects during ion implantation, and results in reduced number of vacancies remaining in the defect clusters. In p-type silicon, a reduction in K-center formation and an enhanced migration of defects are concurrently observed in the illuminated sample implanted with Si ions. These observations are consistent with a model where the injection of excess carriers modifies the defect charge state and impacts their diffusion

Quantum computing with defects

Science.gov (United States)

Varley, Joel

2011-03-01

The development of a quantum computer is contingent upon the identification and design of systems for use as qubits, the basic units of quantum information. One of the most promising candidates consists of a defect in diamond known as the nitrogen-vacancy (NV-1) center, since it is an individually-addressable quantum system that can be initialized, manipulated, and measured with high fidelity at room temperature. While the success of the NV-1 stems from its nature as a localized ``deep-center'' point defect, no systematic effort has been made to identify other defects that might behave in a similar way. We provide guidelines for identifying other defect centers with similar properties. We present a list of physical criteria that these centers and their hosts should meet and explain how these requirements can be used in conjunction with electronic structure theory to intelligently sort through candidate systems. To elucidate these points, we compare electronic structure calculations of the NV-1 center in diamond with those of several deep centers in 4H silicon carbide (SiC). Using hybrid functionals, we report formation energies, configuration-coordinate diagrams, and defect-level diagrams to compare and contrast the properties of these defects. We find that the NC VSi - 1 center in SiC, a structural analog of the NV-1 center in diamond, may be a suitable center with very different optical transition energies. We also discuss how the proposed criteria can be translated into guidelines to discover NV analogs in other tetrahedrally coordinated materials. This work was performed in collaboration with J. R. Weber, W. F. Koehl, B. B. Buckley, A. Janotti, C. G. Van de Walle, and D. D. Awschalom. This work was supported by ARO, AFOSR, and NSF.

A new fundamental hydrogen defect in alkali halides

International Nuclear Information System (INIS)

Morato, S.P.; Luety, F.

1978-01-01

Atom hydrogen in neutral (H 0 ) and negative (H - ) form on substitutional and interstitial lattice sites gives rise to well characterized model defects in alkali-halides (U,U 1 ,U 2 ,U 3 centers), which have been extensively investigated in the past. When studying the photo-decomposition of OH - defects, a new configuration of atomic charged hidrogen was discovered, which can be produced in large quantities in the crystal and is apparently not connected to any other impurity. This new hidrogen defect does not show any pronounced electronic absorption, but displays a single sharp local mode band (at 1114cm -1 in KCl) with a perfect isotope shift. The defect can be produced by various UV or X-ray techniques in crystais doped with OH - , Sh - or H - defects. A detailed study of its formation kinetics at low temperature shows that it is primarily formed by the reaction of a mobile CI 2 - crowdion (H-center) with hidrogen defects [pt

Capture of impurity atoms by defects and the distribution of the complexes under ion bormbardment of growing films

International Nuclear Information System (INIS)

Radzhabov, T.D.; Iskanderova, Z.A.; Arutyunova, E.O.; Samigulin, K.R.

1982-01-01

Theoretical study of capture of impurity gas atoms with defects during ion introduction of the impurity in the process of film growth with simultaneous diffusion has been carried out. Concentration profiles of forned impurity-defect complexes have been calculated analytically and numerically by means of a computer in film depth and in a substrate; basic peculiarities of impurity component formation captured with defects in a wide range of changing basic experimental parameters have been revealed. Effect of impurity capture with defects on amount and distribution of total concentration of impurity atoms and intensity of complete absorption of bombarding ions in films have been analyzed. Shown is a possibility for producing films with a high concentration level and almost uniform distribution of the impurity-defect complexes for real, achievable an experiment, values of process parameters as well as a possibility for increasing complete absorption of gaseous impurity wiht concentration growth of capture defects-traps

Quantum computing with defects.

Science.gov (United States)

Weber, J R; Koehl, W F; Varley, J B; Janotti, A; Buckley, B B; Van de Walle, C G; Awschalom, D D

2010-05-11

Identifying and designing physical systems for use as qubits, the basic units of quantum information, are critical steps in the development of a quantum computer. Among the possibilities in the solid state, a defect in diamond known as the nitrogen-vacancy (NV(-1)) center stands out for its robustness--its quantum state can be initialized, manipulated, and measured with high fidelity at room temperature. Here we describe how to systematically identify other deep center defects with similar quantum-mechanical properties. We present a list of physical criteria that these centers and their hosts should meet and explain how these requirements can be used in conjunction with electronic structure theory to intelligently sort through candidate defect systems. To illustrate these points in detail, we compare electronic structure calculations of the NV(-1) center in diamond with those of several deep centers in 4H silicon carbide (SiC). We then discuss the proposed criteria for similar defects in other tetrahedrally coordinated semiconductors.

Energy landscape of defects in body-centered cubic metals

International Nuclear Information System (INIS)

Alexander, Rebecca

2016-01-01

The structural materials in nuclear reactors are subjected to severe irradiation conditions, leading to changes in their mechanical properties. The aging of these materials raises important issues such as those related to the safety of existing plants and future reactors. In many cases, materials with body-centered cubic bcc crystal structure are used with iron, tungsten, vanadium and tantalum as base metal. Collisions between irradiating particles and atoms constituting materials generate point defects whose migration leads to the formation of clusters responsible for aging. In this thesis, we studied the energetic properties of point defects in the bcc metals mentioned above at the atomic scale. Modeling point defects at the atomic scale can be achieved with different methods that differ only in the quality of the description of the interaction between atoms. Studies using accurate atomic interactions such ab initio calculations are computationally costly making it impossible to directly study clusters of large sizes. The modeling of atomic interactions using semi-empirical potentials reduces the reliability of predictive calculations but allow calculations for large-sized clusters. In this thesis we have developed a unique energy model for dislocation loops as well as for three-dimensional interstitial cluster of type C15. The resulting model has no size limit and can be set entirely by ab initio calculations. To test its robustness for large sizes of clusters we also set this model with semi-empirical potentials calculations and compared the predictions of the model to atomic simulations. With our development we have determined: (i) The relative stability of interstitial dislocation loops according to their Burgers vectors. (ii) The stability of the clusters C15 compared to the type of cluster loop. We showed that the C15 type clusters are more stable when they involve less than 41 interstitials in iron. (iii) In Ta we were able to show the same stability till

Congenital heart defects: the 10-year experience at a single center.

Science.gov (United States)

Aydin, Emine; Aypar, Ebru; Oktem, Ahmet; Ozyuncu, Ozgur; Yurdakok, Murat; Guvener, Murat; Demircin, Metin; Beksac, M Sinan

2018-06-18

We aimed to evaluate congenital heart disease (CHD) cases according to EUROCAT subgroup classification that were diagnosed during the prenatal period in our center. CHDs that were prenatally diagnosed using ultrasonography and confirmed by fetal echocardiography were reviewed over a 10-year period. Subgroup classification was finalized at the post-partum period in terms of the EUROCAT guide 1.3. Congenital heart defect subtypes and obstetric outcomes (gestational week at delivery, birth weight, gender, extracardiac structural abnormalities, karyotype results if performed) were analyzed. The data of 180 cases with CHD was examined. Left ventricular outflow tract obstruction (LVOT) was the most common CHD subtype (57/180; 31.6%), which included 48, five, and four cases of hypoplastic left heart syndrome (HLHS), coarctation of the aorta, and aortic valve atresia/stenosis, respectively. Eighteen pregnancies were terminated; the most common CHD subtype among patients of terminated pregnancies was hypoplastic left heart syndrome (HLHS) (n = 7, 38.8%). The most common extracardiac malformations were a single umbilical artery, esophageal atresia, and situs inversus in our study group. Eighteen of the 96 (18.75%) neonates with CHD died during the neonatal period. The most common CHD subtype was HLHS (7/18; 38%) among the newborns who died after birth. Prenatal diagnosis of a CHD and subgroup classification is very important for clinical decision making, including prenatal management, recommendations for termination of the pregnancy, postnatal management of the patient, and for early referral to pediatric cardiology and cardiovascular surgery centers.

Defect phase diagram for doping of Ga2O3

Science.gov (United States)

Lany, Stephan

2018-04-01

For the case of n-type doping of β-Ga2O3 by group 14 dopants (C, Si, Ge, Sn), a defect phase diagram is constructed from defect equilibria calculated over a range of temperatures (T), O partial pressures (pO2), and dopant concentrations. The underlying defect levels and formation energies are determined from first-principles supercell calculations with GW bandgap corrections. Only Si is found to be a truly shallow donor, C is a deep DX-like (lattice relaxed donor) center, and Ge and Sn have defect levels close to the conduction band minimum. The thermodynamic modeling includes the effect of association of dopant-defect pairs and complexes, which causes the net doping to decline when exceeding a certain optimal dopant concentration. The optimal doping levels are surprisingly low, between about 0.01% and 1% of cation substitution, depending on the (T, pO2) conditions. Considering further the stability constraints due to sublimation of molecular Ga2O, specific predictions of optimized pO2 and Si dopant concentrations are given. The incomplete passivation of dopant-defect complexes in β-Ga2O3 suggests a design rule for metastable doping above the solubility limit.

Energy Frontier Research Center, Center for Materials Science of Nuclear Fuels

International Nuclear Information System (INIS)

Allen, Todd R.

2011-01-01

The Office of Science, Basic Energy Sciences, has funded the INL as one of the Energy Frontier Research Centers in the area of material science of nuclear fuels. This document is the required annual report to the Office of Science that outlines the accomplishments for the period of May 2010 through April 2011. The aim of the Center for Material Science of Nuclear Fuels (CMSNF) is to establish the foundation for predictive understanding of the effects of irradiation-induced defects on thermal transport in oxide nuclear fuels. The science driver of the center's investigation is to understand how complex defect and microstructures affect phonon mediated thermal transport in UO2, and achieve this understanding for the particular case of irradiation-induced defects and microstructures. The center's research thus includes modeling and measurement of thermal transport in oxide fuels with different levels of impurities, lattice disorder and irradiation-induced microstructure, as well as theoretical and experimental investigation of the evolution of disorder, stoichiometry and microstructure in nuclear fuel under irradiation. With the premise that thermal transport in irradiated UO2 is a phonon-mediated energy transport process in a crystalline material with defects and microstructure, a step-by-step approach will be utilized to understand the effects of types of defects and microstructures on the collective phonon dynamics in irradiated UO2. Our efforts under the thermal transport thrust involved both measurement of diffusive phonon transport (an approach that integrates over the entire phonon spectrum) and spectroscopic measurements of phonon attenuation/lifetime and phonon dispersion. Our distinct experimental efforts dovetail with our modeling effort involving atomistic simulation of phonon transport and prediction of lattice thermal conductivity using the Boltzmann transport framework.

Coupling of single nitrogen-vacancy defect centers in diamond nanocrystals to optical antennas and photonic crystal cavities

Energy Technology Data Exchange (ETDEWEB)

Wolters, Janik; Kewes, Guenter; Schell, Andreas W.; Aichele, Thomas; Benson, Oliver [Humboldt-Universitaet zu Berlin, Institut fuer Physik, Berlin (Germany); Nuesse, Nils; Schoengen, Max; Loechel, Bernd [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Berlin (Germany); Hanke, Tobias; Leitenstorfer, Alfred [Department of Physics and Center for Applied Photonics, Universitaet Konstanz, Konstanz (Germany); Bratschitsch, Rudolf [Department of Physics and Center for Applied Photonics, Universitaet Konstanz, Konstanz (Germany); Technische Universitaet Chemnitz, Institut fuer Physik, Chemnitz (Germany)

2012-05-15

We demonstrate the ability to modify the emission properties and enhance the interaction strength of single-photon emitters coupled to nanophotonic structures based on metals and dielectrics. Assembly of individual diamond nanocrystals, metal nanoparticles, and photonic crystal cavities to meta-structures is introduced. Experiments concerning controlled coupling of single defect centers in nanodiamonds to optical nanoantennas made of gold bowtie structures are reviewed. By placing one and the same emitter at various locations with high precision, a map of decay rate enhancements was obtained. Furthermore, we demonstrate the formation of a hybrid cavity quantum electrodynamics system in which a single defect center is coupled to a single mode of a gallium phosphite photonic crystal cavity. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

[Complex skull defects reconstruction with САD/САМ titanium and polyetheretherketone (PEEK) implants].

Science.gov (United States)

Eolchiyan, S A

2014-01-01

Predictable and stable functional and aesthetic result is the aim of priority for the neurosurgeon dealing with the reconstruction of large cranial bone defects and complex-formed skull defects involving cranio-orbital region. the paper presents the experience with САD/САМ titanium and polyetheretherketone (PEEK) implants for complex-formed and large skull bone defects reconstruction. Between 2005 and 2013 nine patients (5 females and 4 males) underwent cranioplasty and cranio-facial reconstruction with insertion of the customized САD/САМ titanium and PEEK implants. Computer-assisted preoperative planning was undertaken by the surgeon and the engineer together in 3 cases to provide accurate implant design. Eight patients had complex-formed and large posttraumatic defects of fronto-orbital (7 cases) and parietal (one case) regions. In two of these cases one-step reconstruction surgery for posttraumatic fronto-orbital defects combined with adjacent orbital roof (one case) and orbito-zygomatic (one case) deformities was performed. One patient underwent one-step primary cranioplasty after cranio-orbital fibrous dysplasia focus resection. Titanium implants were used in 4 cases while PEEK implants - in 5 ones. The follow-up period ranged from 6 months till 8,5 years (median 4,4 years). The accuracy of the implant intraoperative fit was perfect in all cases. Postoperative wounds healed primary and there were no any complications in the series presented. Post-op clinical assessment and CT data testified to high implants precision, good functional and aesthetic outcomes in all patients. САD/САМ titanium and PEEK implants application should allow for optimal reconstruction in the challenging patients with complex-formed and large skull bone defects providing predictable good functional and aesthetic result together with surgery morbidity and duration reduction. Computer-assisted preoperative planning should be undertaken for САD/САМ implants creation in

The defects produced by electron irradiation in tellurium-doped germanium

International Nuclear Information System (INIS)

Fukuoka, Noboru; Saito, Haruo

1989-01-01

The nature of the irradiation induced defects in a germanium single crystal doped with tellurium was studied by DLTS and electrical measurements. The E c -0.21 eV level produced by irradiation with 1.5 MeV electrons was studied using the DLTS technique. It was found that the defect associated with this level is a divacancy. The E-center like defect (group V impurity-vacancy pair) introduces the E c -0.20 eV level in samples doped with a group V impurity. The level introduced by a tellurium (group VI impurity)-vacancy pair is deeper. The E c -0.16 eV level was generated by annealing at 430 K. A tellurium-vacancies complex is proposed as the defect associated with this level. (author)

Nonlinear stability of source defects in the complex Ginzburg–Landau equation

International Nuclear Information System (INIS)

Beck, Margaret; Nguyen, Toan T; Sandstede, Björn; Zumbrun, Kevin

2014-01-01

In an appropriate moving coordinate frame, source defects are time-periodic solutions to reaction–diffusion equations that are spatially asymptotic to spatially periodic wave trains whose group velocities point away from the core of the defect. In this paper, we rigorously establish nonlinear stability of spectrally stable source defects in the complex Ginzburg–Landau equation. Due to the outward transport at the far field, localized perturbations may lead to a highly non-localized response even on the linear level. To overcome this, we first investigate in detail the dynamics of the solution to the linearized equation. This allows us to determine an approximate solution that satisfies the full equation up to and including quadratic terms in the nonlinearity. This approximation utilizes the fact that the non-localized phase response, resulting from the embedded zero eigenvalues, can be captured, to leading order, by the nonlinear Burgers equation. The analysis is completed by obtaining detailed estimates for the resolvent kernel and pointwise estimates for Green's function, which allow one to close a nonlinear iteration scheme. (paper)

Coenzyme Q10 defects may be associated with a deficiency of Q10-independent mitochondrial respiratory chain complexes

Directory of Open Access Journals (Sweden)

Konstantina Fragaki

Full Text Available BACKGROUND: Coenzyme Q10 (CoQ10 or ubiquinone deficiency can be due either to mutations in genes involved in CoQ10 biosynthesis pathway, or to mutations in genes unrelated to CoQ10 biosynthesis. CoQ10 defect is the only oxidative phosphorylation disorder that can be clinically improved after oral CoQ10 supplementation. Thus, early diagnosis, first evoked by mitochondrial respiratory chain (MRC spectrophotometric analysis, then confirmed by direct measurement of CoQ10 levels, is of critical importance to prevent irreversible damage in organs such as the kidney and the central nervous system. It is widely reported that CoQ10 deficient patients present decreased quinone-dependent activities (segments I + III or G3P + III and II + III while MRC activities of complexes I, II, III, IV and V are normal. We previously suggested that CoQ10 defect may be associated with a deficiency of CoQ10-independent MRC complexes. The aim of this study was to verify this hypothesis in order to improve the diagnosis of this disease. RESULTS: To determine whether CoQ10 defect could be associated with MRC deficiency, we quantified CoQ10 by LC-MSMS in a cohort of 18 patients presenting CoQ10-dependent deficiency associated with MRC defect. We found decreased levels of CoQ10 in eight patients out of 18 (45 %, thus confirming CoQ10 disease. CONCLUSIONS: Our study shows that CoQ10 defect can be associated with MRC deficiency. This could be of major importance in clinical practice for the diagnosis of a disease that can be improved by CoQ10 supplementation.

Vertebral defect, anal atresia, cardiac defect, tracheoesophageal fistula/esophageal atresia, renal defect, and limb defect association with Mayer-Rokitansky-Küster-Hauser syndrome in co-occurrence

DEFF Research Database (Denmark)

Bjørsum-Meyer, Thomas; Herlin, Morten; Qvist, Niels

2016-01-01

Background: The vertebral defect, anal atresia, cardiac defect, tracheoesophageal fistula/esophageal atresia, renal defect, and limb defect association and Mayer-Rokitansky-Küster-Hauser syndrome are rare conditions. We aimed to present two cases with the vertebral defect, anal atresia, cardiac...... defect, tracheoesophageal fistula/esophageal atresia, renal defect, and limb defect association and Mayer-Rokitansky-Küster-Hauser co-occurrence from our local surgical center and through a systematic literature search detect published cases. Furthermore, we aimed to collect existing knowledge...... in the embryopathogenesis and genetics in order to discuss a possible link between the vertebral defect, anal atresia, cardiac defect, tracheoesophageal fistula/esophageal atresia, renal defect, and limb defect association and Mayer-Rokitansky-Küster-Hauser syndrome. Case presentation: Our first case was a white girl...

Defect phase diagram for doping of Ga2O3

Directory of Open Access Journals (Sweden)

Stephan Lany

2018-04-01

Full Text Available For the case of n-type doping of β-Ga2O3 by group 14 dopants (C, Si, Ge, Sn, a defect phase diagram is constructed from defect equilibria calculated over a range of temperatures (T, O partial pressures (pO2, and dopant concentrations. The underlying defect levels and formation energies are determined from first-principles supercell calculations with GW bandgap corrections. Only Si is found to be a truly shallow donor, C is a deep DX-like (lattice relaxed donor center, and Ge and Sn have defect levels close to the conduction band minimum. The thermodynamic modeling includes the effect of association of dopant-defect pairs and complexes, which causes the net doping to decline when exceeding a certain optimal dopant concentration. The optimal doping levels are surprisingly low, between about 0.01% and 1% of cation substitution, depending on the (T, pO2 conditions. Considering further the stability constraints due to sublimation of molecular Ga2O, specific predictions of optimized pO2 and Si dopant concentrations are given. The incomplete passivation of dopant-defect complexes in β-Ga2O3 suggests a design rule for metastable doping above the solubility limit.

Perforator chimerism for the reconstruction of complex defects: A new chimeric free flap classification system.

Science.gov (United States)

Kim, Jeong Tae; Kim, Youn Hwan; Ghanem, Ali M

2015-11-01

Complex defects present structural and functional challenges to reconstructive surgeons. When compared to multiple free flaps or staged reconstruction, the use of chimeric flaps to reconstruct such defects have many advantages such as reduced number of operative procedures and donor site morbidity as well as preservation of recipient vessels. With increased popularity of perforator flaps, chimeric flaps' harvest and design has benefited from 'perforator concept' towards more versatile and better reconstruction solutions. This article discusses perforator based chimeric flaps and presents a practice based classification system that incorporates the perforator flap concept into "Perforator Chimerism". The authors analyzed a variety of chimeric patterns used in 31 consecutive cases to present illustrative case series and their new classification system. Accordingly, chimeric flaps are classified into four types. Type I: Classical Chimerism, Type II: Anastomotic Chimerism, Type III: Perforator Chimerism and Type IV Mixed Chimerism. Types I on specific source vessel anatomy whilst Type II requires microvascular anastomosis to create the chimeric reconstructive solution. Type III chimeric flaps utilizes the perforator concept to raise two components of tissues without microvascular anastomosis between them. Type IV chimeric flaps are mixed type flaps comprising any combination of Types I to III. Incorporation of the perforator concept in planning and designing chimeric flaps has allowed safe, effective and aesthetically superior reconstruction of complex defects. The new classification system aids reconstructive surgeons and trainees to understand chimeric flaps design, facilitating effective incorporation of this important reconstructive technique into the armamentarium of the reconstruction toolbox. Copyright © 2015 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

Vertebral defect, anal atresia, cardiac defect, tracheoesophageal fistula/esophageal atresia, renal defect, and limb defect association with Mayer-Rokitansky-Küster-Hauser syndrome in co-occurrence: two case reports and a review of the literature.

Science.gov (United States)

Bjørsum-Meyer, Thomas; Herlin, Morten; Qvist, Niels; Petersen, Michael B

2016-12-21

The vertebral defect, anal atresia, cardiac defect, tracheoesophageal fistula/esophageal atresia, renal defect, and limb defect association and Mayer-Rokitansky-Küster-Hauser syndrome are rare conditions. We aimed to present two cases with the vertebral defect, anal atresia, cardiac defect, tracheoesophageal fistula/esophageal atresia, renal defect, and limb defect association and Mayer-Rokitansky-Küster-Hauser co-occurrence from our local surgical center and through a systematic literature search detect published cases. Furthermore, we aimed to collect existing knowledge in the embryopathogenesis and genetics in order to discuss a possible link between the vertebral defect, anal atresia, cardiac defect, tracheoesophageal fistula/esophageal atresia, renal defect, and limb defect association and Mayer-Rokitansky-Küster-Hauser syndrome. Our first case was a white girl delivered by caesarean section at 37 weeks of gestation; our second case was a white girl born at a gestational age of 40 weeks. A co-occurrence of vertebral defect, anal atresia, cardiac defect, tracheoesophageal fistula/esophageal atresia, renal defect, and limb defect association and Mayer-Rokitansky-Küster-Hauser syndrome was diagnosed in both cases. We performed a systematic literature search in PubMed ((VACTERL) OR (VATER)) AND ((MRKH) OR (Mayer-Rokitansky-Küster-Hauser) OR (mullerian agenesis) OR (mullerian aplasia) OR (MURCS)) without limitations. A similar search was performed in Embase and the Cochrane library. We added two cases from our local center. All cases (n = 9) presented with anal atresia and renal defect. Vertebral defects were present in eight patients. Rectovestibular fistula was confirmed in seven patients. Along with the uterovaginal agenesis, fallopian tube aplasia appeared in five of nine cases and in two cases ovarian involvement also existed. The co-occurrence of the vertebral defect, anal atresia, cardiac defect, tracheoesophageal fistula/esophageal atresia, renal

Defects in the COG complex and COG-related trafficking regulators affect neuronal Golgi function.

Directory of Open Access Journals (Sweden)

Leslie K Climer

2015-10-01

Full Text Available The Conserved Oligomeric Golgi (COG complex is an evolutionarily conserved hetero-octameric protein complex that has been proposed to organize vesicle tethering at the Golgi apparatus. Defects in seven of the eight COG subunits are linked to Congenital Disorders of Glycosylation (CDG-type II, a family of rare diseases involving misregulation of protein glycosylation, alterations in Golgi structure, variations in retrograde trafficking through the Golgi and system-wide clinical pathologies. A troublesome aspect of these diseases are the neurological pathologies such as low IQ, microcephaly and cerebellar atrophy. The essential function of the COG complex is dependent upon interactions with other components of trafficking machinery, such as Rab-GTPases and SNAREs. COG-interacting Rabs and SNAREs have been implicated in neurodegenerative diseases like Alzheimer’s disease and Parkinson’s disease. Defects in Golgi maintenance disrupts trafficking and processing of essential proteins, frequently associated with and contributing to compromised neuron function and human disease. Despite the recent advances in molecular neuroscience, the subcellular bases for most neurodegenerative diseases are poorly understood. This article gives an overview of the potential contributions of the COG complex and its Rab and SNARE partners in the pathogenesis of different neurodegenerative disorders.

Natural disease course and genotype-phenotype correlations in Complex I deficiency caused by nuclear gene defects

DEFF Research Database (Denmark)

Koene, S; Rodenburg, R J; van der Knaap, M S

2012-01-01

cases and 126 from literature) with mutations in nuclear genes encoding structural complex I proteins or those involved in its assembly. Complex I deficiency caused by a nuclear gene defect is usually a non-dysmorphic syndrome, characterized by severe multi-system organ involvement and a poor prognosis...

Vacancy-impurity centers in diamond: prospects for synthesis and applications

Science.gov (United States)

Ekimov, E. A.; Kondrin, M. V.

2017-06-01

The bright luminescence of impurity-vacancy complexes, combined with high chemical and radiation resistance, makes diamond an attractive platform for the production of single-photon emitters and luminescent biomarkers for applications in nanoelectronics and medicine. Two representatives of this kind of defects in diamond, silicon-vacancy (SiV) and germanium-vacancy (GeV) centers, are discussed in this review; their similarities and differences are demonstrated in terms of the more thoroughly studied nitrogen-vacancy (NV) complexes. The recent discovery of GeV luminescent centers opens a unique opportunity for the controlled synthesis of single-photon emitters in nanodiamonds. We demonstrate prospects for the high-pressure high-temperature (HPHT) technique to create single-photon emitters, not only as an auxiliary to chemical vapor deposition (CVD) and ion-implantation methods but also as a primary synthesis tool for producing color centers in nanodiamonds. Besides practical applications, comparative studies of these two complexes, which belong to the same structural class of defects, have a fundamental importance for deeper understanding of shelving levels, the electronic structure, and optical properties of these centers. In conclusion, we discuss several open problems regarding the structure, charge state, and practical application of these centers, which still require a solution.

Effect of the V{sub As}V{sub Ga} complex defect doping on properties of the semi-insulating GaAs

Energy Technology Data Exchange (ETDEWEB)

Ma, Deming, E-mail: xautmdm@163.com; Qiao, Hongbo; Shi, Wei; Li, Enling [Department of Applied Physics, Xi' an University of Technology, Xi' an 710054 (China)

2014-04-21

The different position V{sub As}V{sub Ga} cluster defect doping in semi-insulating (SI) GaAs has been studied by first-principles calculation based on hybrid density functional theory. Our calculated results show that EL6 level is formed due to the V{sub As}V{sub Ga} complex defect, which is very close to the experimental result. It provides the explanation of the absorption of laser with the wavelength beyond in semi-insulating GaAs. The formation energy of V{sub As}V{sub Ga} complex defect is found to decrease from surface to interior gradually. The conduction band minima and valence band maxima of GaAs (001) surface with the V{sub As}V{sub Ga} complex defect are all located at Γ point, and some defect levels are produced in the forbidden band. In contrast, the conduction band minima and valence band maxima of GaAs with the interior V{sub As}V{sub Ga} complex defect are not located at the same k-point, so it might involve the change of momentum in the electron transition process. The research will help strengthen the understanding of photoelectronic properties and effectively guide the preparation of the SI-GaAs materials.

Ventricular septal defect in children and adolescents in Angola: experience of a tertiary center.

Science.gov (United States)

Manuel, Valdano; Morais, Humberto; Manuel, Ana; David, Bruna; Gamboa, Sebastiana

2014-10-01

This is the first study in Angola with the aim of characterizing ventricular septal defect (VSD) among children and adolescents. A cross-sectional study based on echocardiographic records of the largest pediatric cardiology center in Angola included all children and adolescents (0 to 18 years old) with VSD between April 2010 and March 2011. The diagnosis was made by transthoracic and Doppler echocardiography with a Medison SA 8000 system. The sample was divided into two groups: Group 1, isolated VSD; and Group 2, VSD associated with other congenital heart defects (CHDs). Age, gender, type of VSD, associated CHDs and genetic syndromes were assessed. A total of 490 CHDs were diagnosed, of which 283 were VSDs. In Group 1 (140, 49%) the mean age was 29±36 months. The most frequent age (mode) at diagnosis was 24 months. There was no predominance of gender (ratio 1:1). The majority (127, 91%) had perimembranous VSD. In Group 2 (143, 51%) 113 patients (79%) had one, 27 patients (19%) had two and three patients (2%) had three other CHDs. Trisomy 21 was the most common genetic syndrome (23, 96%). The study shows that VSD is the most common CHD in childhood, the diagnosis is made late and almost half of VSDs are associated with other CHDs. Copyright © 2014 Sociedade Portuguesa de Cardiologia. Published by Elsevier España. All rights reserved.

Vacancy complexes induce long-range ferromagnetism in GaN

KAUST Repository

Zhang, Zhenkui

2014-11-14

By means of density functional theory, we argue that ferromagnetism in GaN can be induced by vacancy complexes. Spin polarization originates from the charge compensation between neutral N and Ga vacancies. Defect formation energy calculations predict that a vacancy complex of two positively charged N vacancies and one doubly negative Ga vacancy is likely to form. This defect complex induces a net moment of 1 μB, which is localized around the negative Ga center and exhibits pronounced in-plane ferromagnetic coupling. In contrast to simple Ga vacancy induced ferromagnetism, the proposed picture is in line with the fact that N vacancies have a low formation energy. Formation energies indicate mutual stabilization of the intrinsic defects in GaN.

Vacancy complexes induce long-range ferromagnetism in GaN

Energy Technology Data Exchange (ETDEWEB)

Zhang, Zhenkui; Schwingenschlögl, Udo, E-mail: Udo.Schwingenschlogl@kaust.edu.sa, E-mail: Iman.Roqan@kaust.edu.sa; Roqan, Iman S., E-mail: Udo.Schwingenschlogl@kaust.edu.sa, E-mail: Iman.Roqan@kaust.edu.sa [Physical Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900 (Saudi Arabia)

2014-11-14

By means of density functional theory, we argue that ferromagnetism in GaN can be induced by vacancy complexes. Spin polarization originates from the charge compensation between neutral N and Ga vacancies. Defect formation energy calculations predict that a vacancy complex of two positively charged N vacancies and one doubly negative Ga vacancy is likely to form. This defect complex induces a net moment of 1 μ{sub B}, which is localized around the negative Ga center and exhibits pronounced in-plane ferromagnetic coupling. In contrast to simple Ga vacancy induced ferromagnetism, the proposed picture is in line with the fact that N vacancies have a low formation energy. Formation energies indicate mutual stabilization of the intrinsic defects in GaN.

Vacancy complexes induce long-range ferromagnetism in GaN

KAUST Repository

Zhang, Zhenkui; Schwingenschlö gl, Udo; Roqan, Iman S.

2014-01-01

By means of density functional theory, we argue that ferromagnetism in GaN can be induced by vacancy complexes. Spin polarization originates from the charge compensation between neutral N and Ga vacancies. Defect formation energy calculations predict that a vacancy complex of two positively charged N vacancies and one doubly negative Ga vacancy is likely to form. This defect complex induces a net moment of 1 μB, which is localized around the negative Ga center and exhibits pronounced in-plane ferromagnetic coupling. In contrast to simple Ga vacancy induced ferromagnetism, the proposed picture is in line with the fact that N vacancies have a low formation energy. Formation energies indicate mutual stabilization of the intrinsic defects in GaN.

Monti’s procedure as an alternative technique in complex urethral distraction defect

Directory of Open Access Journals (Sweden)

Jalil Hosseini

2010-06-01

Full Text Available PURPOSE: Pelvic fracture urethral distraction defect is usually managed by the end to end anastomotic urethroplasty. Surgical repair of those patients with post-traumatic complex posterior urethral defects, who have undergone failed previous surgical treatments, remains one of the most challenging problems in urology. Appendix urinary diversion could be used in such cases. However, the appendix tissue is not always usable. We report our experience on management of patients with long urethral defect with history of one or more failed urethroplasties by Monti channel urinary diversion. MATERIALS AND METHODS: From 2001 to 2007, we evaluated data from 8 male patients aged 28 to 76 years (mean age 42.5 in whom the Monti technique was performed. All cases had history of posterior urethral defect with one or more failed procedures for urethral reconstruction including urethroplasty. A 2 to 2.5 cm segment of ileum, which had a suitable blood supply, was cut. After the re-anastomosis of the ileum, we closed the opened ileum transversely surrounding a 14-16 Fr urethral catheter using running Vicryl sutures. The newly built tube was used as an appendix during diversion. RESULTS: All patients performed catheterization through the conduit without difficulty and stomal stenosis. Mild stomal incontinence occurred in one patient in the supine position who became continent after adjustment of the catheterization intervals. There was no dehiscence, necrosis or perforation of the tube. CONCLUSION: Based on our data, Monti’s procedure seems to be a valuable technique in patients with very long complicated urethral defect who cannot be managed with routine urethroplastic techniques.

Defect formation in heavily doped Si upon irradiation

International Nuclear Information System (INIS)

Gubskaya, V.I.; Kuchinskii, P.V.; Lomako, V.M.

1981-01-01

The rates of the carrier removal and radiation defect introduction into n- and p-Si in the concentration range of 10 14 to 10 17 cm -3 upon 7-MeV-electron irradiation have been studied. The spectrum of the vacancy-type defects, defining the carrier removal rate in lightly doped crystals has been found. With doping level increase the carrier removal rate grows irrespective of conductivity type, and at n 0 , p 0 > 10 17 cm -3 is close to the total displacement number. At the same time a decrease in the introduction rate of the known vacancy-type defects is observed. x It is shown that a considerable growth of the carrier removal rate is defined neither by introduction of shallow compensating centers, nor by change in the primary defect charge state. It is suggested that at high doping impurity concentrations compensation in Si is due to the introduction of complexes doping impurity-interstitial or (impurity atom-interstitial) + vacancy, which give deep levels. (author)

Nature of oxygen donors and radiation defects in oxygen-doped germanium

International Nuclear Information System (INIS)

Fukuoka, Noboru; Atobe, Kozo; Honda, Makoto; Matsuda, Koji.

1991-01-01

The nature of oxygen donors and radiation defects in oxygen-doped germanium were studied through measurements of the infrared absorption spectrum, deep level transient spectroscopy spectrum and carrier concentration. It is revealed that a new donor is not formed in oxygen-doped germanium. An A-center (interstitial oxygen-vacancy pair) forms a complex with a thermal donor in its annealing stage at 60degC-140degC. The introduction rate of defects by 1.5 MeV electron irradiation was enhanced in thermal-donor-doped samples. (author)

[Progression of nerve fiber layer defects in retrobulbar optic neuritis by the macular ganglion cell complex].

Science.gov (United States)

Hong, D; Bosc, C; Chiambaretta, F

2017-11-01

Recent studies with SD OCT had shown early axonal damage to the macular ganglion cell complex (which consists of the three innermost layers of the retina: Inner Plexiform Layer [IPL], Ganglion Cell Layer [GCL], Retinal Nerve Fibre layer [RNFL]) in optic nerve pathology. Retrobulbar optic neuritis (RBON), occurring frequently in demyelinating diseases, leads to atrophy of the optic nerve fibers at the level of the ganglion cell axons, previously described in the literature. The goal of this study is to evaluate the progression of optic nerve fiber defects and macular ganglion cell complex defects with the SPECTRALIS OCT via a reproducible method by calculating a mean thickness in each quadrant after an episode of retrobulbar optic neuritis. This is a prospective monocentric observational study including 8 patients at the Clermont-Ferrand university medical center. All patients underwent ocular examination with macular and disc OCT analysis and a Goldmann visual field at the time of inclusion (onset or recurrence of RBON), at 3 months and at 6 months. Patients were 40-years-old on average at the time of inclusion. After 6 months of follow-up, there was progression of the atrophy of the macular ganglion cell complex in the affected eye on (11.5% or 11μm) predominantly inferonasally (13.9% or 16μm) and superonasally (12.9% or 14μm) while the other eye remained stable. The decrease in thickness occurred mainly in the most internal 3 layers of the retina. On average, the loss in thickness of the peripapillary RNFL was predominantly inferotemporal (24.9% or 39μm) and superotemporal (21.8% or 28μm). In 3 months of progression, the loss of optic nerve fibers is already seen on macular and disc OCT after an episode of RBON, especially in inferior quadrants in spite of the improvement in the Goldmann visual field and visual acuity. Segmentation by quadrant was used here to compare the progression of the defect by region compared to the fovea in a global and reproducible

Atomic-Scale Structure of the Tin DX Center and Other Related Defects in Aluminum Gallium Arsenide Semiconductors Using Moessbauer Spectroscopy.

Science.gov (United States)

Greco, Luigi Alessandro

/or radiation-induced capture. After annealing the x = 0.25 sample at 1000^circC for 2 hours under a Ga + Al overpressure, evidence of PPC was found via Hall measurements but no effect was seen by Mossbauer suggesting radiation-induced capture and/or non-nearest-neighbor lattice relaxation. The Ga + Al overpressure also served to decrease the loss of Sn through the SiO _{rm x} film, possibly through the removal of Ga and Al vacancies. The x = 0.15 absorber showed a persistent 15-18% change in the electrical resistance (10% change in n) between the light and dark. However, the observation of this effect was not apparent, even assuming negative-U (2 electron) behavior, in the Mossbauer measurements. This was also consistent with EXAFS results. These studies do not support the broken-bond model of Chadi and Chang, which is considered to be a widely accepted atomic-scale model of the DX center. A defect complex consisting of a substitutional Sn_{rm Ga(Al) }^+ site, and a (V_{ rm III}^-Al_{ rm As}^{-2}) complex, which localizes 3 electrons and may not be a nearest-neighbor to the donor, was chosen for the DX center in the x = 0.15 sample which supports EXAFS, recent positron annihilation and these Mossbauer studies.

Omphalocele, exstrophy of cloaca, imperforate anus, and spinal defect complex, multiple major reconstructive surgeries needed

Directory of Open Access Journals (Sweden)

Nada Neel

2018-01-01

Full Text Available OEIS complex is a rare combination of serious birth defects including omphalocele, exstrophy of cloaca, imperforate anus, and spinal defects. The aim of managements has shifted from merely providing survival to improve patient outcomes and quality of life with higher level of physical and social independence. Multiple complicated reconstructive surgeries always needed for achieving the goals of treatment. In this case report, we aimed to present our surgical approach for this rare abnormality to achieve functionally and socially acceptable outcome.

An inherited immunoglobulin class-switch recombination deficiency associated with a defect in the INO80 chromatin remodeling complex.

Science.gov (United States)

Kracker, Sven; Di Virgilio, Michela; Schwartzentruber, Jeremy; Cuenin, Cyrille; Forveille, Monique; Deau, Marie-Céline; McBride, Kevin M; Majewski, Jacek; Gazumyan, Anna; Seneviratne, Suranjith; Grimbacher, Bodo; Kutukculer, Necil; Herceg, Zdenko; Cavazzana, Marina; Jabado, Nada; Nussenzweig, Michel C; Fischer, Alain; Durandy, Anne

2015-04-01

Immunoglobulin class-switch recombination defects (CSR-D) are rare primary immunodeficiencies characterized by impaired production of switched immunoglobulin isotypes and normal or elevated IgM levels. They are caused by impaired T:B cooperation or intrinsic B cell defects. However, many immunoglobulin CSR-Ds are still undefined at the molecular level. This study's objective was to delineate new causes of immunoglobulin CSR-Ds and thus gain further insights into the process of immunoglobulin class-switch recombination (CSR). Exome sequencing in 2 immunoglobulin CSR-D patients identified variations in the INO80 gene. Functional experiments were performed to assess the function of INO80 on immunoglobulin CSR. We identified recessive, nonsynonymous coding variations in the INO80 gene in 2 patients affected by defective immunoglobulin CSR. Expression of wild-type INO80 in patients' fibroblastic cells corrected their hypersensitivity to high doses of γ-irradiation. In murine CH12-F3 cells, the INO80 complex accumulates at Sα and Eμ regions of the IgH locus, and downregulation of INO80 as well as its partners Reptin and Pontin impaired CSR. In addition, Reptin and Pontin were shown to interact with activation-induced cytidine deaminase. Finally, an abnormal separation of sister chromatids was observed upon INO80 downregulation in CH12-F3 cells, pinpointing its role in cohesin activity. INO80 deficiency appears to be associated with defective immunoglobulin CSR. We propose that the INO80 complex modulates cohesin function that may be required during immunoglobulin switch region synapsis. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

Omphalocele, exstrophy of bladder, imperforate anus and spinal defect complex with genital anomalies in a late preterm infant

Directory of Open Access Journals (Sweden)

Faisal Othman Al-Qurashi

2017-01-01

Full Text Available Omphalocele, exstrophy of the bladder, imperforate anus and spinal defect (OEIS complex is a rare congenital multisystemic malformation representing unique anomalies. It was first reported in 1978 through a series of cases with an abnormality of body wall development. We are reporting a case of an infant of 36 weeks gestation, with a family history of consanguinity and oral contraceptive pill intake that was discontinued when the mother was 1-month pregnant. The neonatal examination revealed findings that were consistent with OEIS complex along with the presence of genital anomalies. The infant required multi-staged surgical intervention. We conclude that this case report might illustrate some of the possible risk factors and variability of OEIS complex.

Investigation of the oxygen-vacancy (A-center) defect complex profile in neutron irradiated high resistivity silicon junction particle detectors

International Nuclear Information System (INIS)

Li, Zheng; Kraner, H.W.; Verbitskaya, E.; Eremin, V.; Ivanov, A.; Rubinelli, F.A.; Fonash, S.J.

1992-02-01

Distributions of the A-center (oxygen-vacancy) in neutron silicon detectors have been studied using Deep Level Transient Spectroscopy. A-centers have been found to be nearly uniformly distributed in the silicon water depth for medium resistivity (0.1 - 0.2 kΩ-cm) silicon detectors. A positive filling pulse was needed to detect the A-centers in high resistivity (>4 kΩ-cm) silicon detectors, and this effect was found to be dependent on the oxidation temperature. A discussion of this effect is presented. 16 refs

Carbon-hydrogen defects with a neighboring oxygen atom in n-type Si

Science.gov (United States)

Gwozdz, K.; Stübner, R.; Kolkovsky, Vl.; Weber, J.

2017-07-01

We report on the electrical activation of neutral carbon-oxygen complexes in Si by wet-chemical etching at room temperature. Two deep levels, E65 and E75, are observed by deep level transient spectroscopy in n-type Czochralski Si. The activation enthalpies of E65 and E75 are obtained as EC-0.11 eV (E65) and EC-0.13 eV (E75). The electric field dependence of their emission rates relates both levels to single acceptor states. From the analysis of the depth profiles, we conclude that the levels belong to two different defects, which contain only one hydrogen atom. A configuration is proposed, where the CH1BC defect, with hydrogen in the bond-centered position between neighboring C and Si atoms, is disturbed by interstitial oxygen in the second nearest neighbor position to substitutional carbon. The significant reduction of the CH1BC concentration in samples with high oxygen concentrations limits the use of this defect for the determination of low concentrations of substitutional carbon in Si samples.

Cumulative complexity: a functional, patient-centered model of patient complexity can improve research and practice.

Science.gov (United States)

Shippee, Nathan D; Shah, Nilay D; May, Carl R; Mair, Frances S; Montori, Victor M

2012-10-01

To design a functional, patient-centered model of patient complexity with practical applicability to analytic design and clinical practice. Existing literature on patient complexity has mainly identified its components descriptively and in isolation, lacking clarity as to their combined functions in disrupting care or to how complexity changes over time. The authors developed a cumulative complexity model, which integrates existing literature and emphasizes how clinical and social factors accumulate and interact to complicate patient care. A narrative literature review is used to explicate the model. The model emphasizes a core, patient-level mechanism whereby complicating factors impact care and outcomes: the balance between patient workload of demands and patient capacity to address demands. Workload encompasses the demands on the patient's time and energy, including demands of treatment, self-care, and life in general. Capacity concerns ability to handle work (e.g., functional morbidity, financial/social resources, literacy). Workload-capacity imbalances comprise the mechanism driving patient complexity. Treatment and illness burdens serve as feedback loops, linking negative outcomes to further imbalances, such that complexity may accumulate over time. With its components largely supported by existing literature, the model has implications for analytic design, clinical epidemiology, and clinical practice. Copyright © 2012 Elsevier Inc. All rights reserved.

Complex of GRAD programs for analytical calculation of radiation defects generation in solids

International Nuclear Information System (INIS)

Suvorov, A.L.; Zabolotnyj, V.T.; Babaev, V.P.

1989-01-01

Complex of programms for analytical calculation of generation of radiation defects (GRAD) in solids, and also of their recombination during cascade area relaxation and postradiation annealing, of mass removing by atomic collisions in volume (mixing) and through the surface (sputtering), of structure - phase state and property changes is suggested. The complex volume is less than 10 KBytes and it may be realized by computer of any type. Satisfactional agreement with more wide range of experimental data in comparison with tradition models is obtained. 27 refs.; 2 figs

On holographic defect entropy

International Nuclear Information System (INIS)

Estes, John; Jensen, Kristan; O’Bannon, Andy; Tsatis, Efstratios; Wrase, Timm

2014-01-01

We study a number of (3+1)- and (2+1)-dimensional defect and boundary conformal field theories holographically dual to supergravity theories. In all cases the defects or boundaries are planar, and the defects are codimension-one. Using holography, we compute the entanglement entropy of a (hemi-)spherical region centered on the defect (boundary). We define defect and boundary entropies from the entanglement entropy by an appropriate background subtraction. For some (3+1)-dimensional theories we find evidence that the defect/boundary entropy changes monotonically under certain renormalization group flows triggered by operators localized at the defect or boundary. This provides evidence that the g-theorem of (1+1)-dimensional field theories generalizes to higher dimensions

Extrusion product defects: a statistical study

International Nuclear Information System (INIS)

Qamar, S.Z.; Arif, A.F.M.; Sheikh, A.K.

2003-01-01

In any manufacturing environment, defects resulting in rework or rejection are directly related to product cost and quality, and indirectly linked with process, tooling and product design. An analysis of product defects is therefore integral to any attempt at improving productivity, efficiency and quality. Commercial aluminum extrusion is generally a hot working process and consists of a series of different but integrated operations: billet preheating and sizing, die set and container preheating, billet loading and deformation, product sizing and stretching/roll-correction, age hardening, and painting/anodizing. Product defects can be traced back to problems in billet material and preparation, die and die set design and maintenance, process variable aberrations (ram speed, extrusion pressure, container temperature, etc), and post-extrusion treatment (age hardening, painting/anodizing, etc). The current paper attempts to analyze statistically the product defects commonly encountered in a commercial hot aluminum extrusion setup. Real-world rejection data, covering a period of nine years, has been researched and collected from a local structural aluminum extrusion facility. Rejection probabilities have been calculated for all the defects studied. The nine-year rejection data have been statistically analyzed on the basis of (i) an overall breakdown of defects, (ii) year-wise rejection behavior, (iii) breakdown of defects in each of three cost centers: press, anodizing, and painting. (author)

Characteristics of accumulation of recombination centers due to irradiation of p-type Si

International Nuclear Information System (INIS)

Kazakevich, L.A.; Lugakov, P.F.; Filippov, I.M.

1989-01-01

Irradiation of Czochralski-grown p-type Si single crystals results primarily in creation of recombination-active radiation defects which give rise to a donor energy level at E v + 0.30-0.38 eV in the band gap. The ideas on the structure and mechanisms of formation of these radiation defects are continuously evolving and at present the most widely held view is that which assumes that the K centers can be carbon-oxygen-divacancy complexes or interstitial carbon-interstitial oxygen pairs. The authors investigated the recombination properties of such centers

Cardiac fusion and complex congenital cardiac defects in thoracopagus twins: diagnostic value of cardiac CT

Energy Technology Data Exchange (ETDEWEB)

Goo, Hyun Woo [University of Ulsan College of Medicine, Asan Medical Center, Department of Radiology and Research Institute of Radiology, Seoul (Korea, Republic of); Park, Jeong-Jun [University of Ulsan College of Medicine, Asan Medical Center, Department of Pediatric Cardiac Surgery, Seoul (Korea, Republic of); Kim, Ellen Ai-Rhan [University of Ulsan College of Medicine, Asan Medical Center, Division of Neonatology, Department of Pediatrics, Seoul (Korea, Republic of); Won, Hye-Sung [University of Ulsan College of Medicine, Asan Medical Center, Department of Obstetrics and Gynecology, Seoul (Korea, Republic of)

2014-09-15

Most thoracopagus twins present with cardiac fusion and associated congenital cardiac defects, and assessment of this anatomy is of critical importance in determining patient care and outcome. Cardiac CT with electrocardiographic triggering provides an accurate and quick morphological assessment of both intracardiac and extracardiac structures in newborns, making it the best imaging modality to assess thoracopagus twins during the neonatal period. In this case report, we highlight the diagnostic value of cardiac CT in thoracopagus twins with an interatrial channel and complex congenital cardiac defects. (orig.)

Sonic Hedgehog mutations are not a common cause of congenital hypopituitarism in the absence of complex midline cerebral defects.

Science.gov (United States)

Paulo, Sabrina Soares; Fernandes-Rosa, Fábio L; Turatti, Wendy; Coeli-Lacchini, Fernanda Borchers; Martinelli, Carlos E; Nakiri, Guilherme S; Moreira, Ayrton C; Santos, Antônio C; de Castro, Margaret; Antonini, Sonir R

2015-04-01

Sonic Hedgehog (SHH) and GLI2, an obligatory mediator of SHH signal transduction, are holoprosencephaly (HPE)-associated genes essential in pituitary formation. GLI2 variants have been found in patients with congenital hypopituitarism without complex midline cerebral defects (MCD). However, data on the occurrence of SHH mutations in these patients are limited. We screened for SHH and GLI2 mutations or copy number variations (CNV) in patients with congenital hypopituitarism without MCD or with variable degrees of MCD. Detailed data on clinical, laboratory and neuroimaging findings of 115 patients presenting with congenital hypopituitarism without MCD, septo-optic dysplasia or HPE were analysed. The SHH and GLI2 genes were directly sequenced, and the presence of gene CNV was analysed by multiplex ligation-dependent probe amplification (MLPA). Anterior pituitary deficiency was found in 74% and 53% of patients with SOD or HPE, respectively. Diabetes insipidus was common in patients with HPE (47%) but infrequent in patients with congenital hypopituitarism or SOD (7% and 8%, respectively). A single heterozygous nonsense SHH mutation (p.Tyr175Ter) was found in a patient presenting with hypopituitarism and alobar HPE. No other SHH mutations or CNV were found. Nine GLI2 variations (8 missense and 1 frameshift) including a homozygous and a compound heterozygous variation were found in patients with congenital hypopituitarism or SOD, but not in HPE patients. No GLI2 CNV were found. SHH mutations or copy number variations are not a common cause of congenital hypopituitarism in patients without complex midline cerebral defects. GLI2 variants are found in some patients with congenital hypopituitarism without complex midline cerebral defects or septo-optic dysplasia. However, functional analyses of these variants are needed to strengthen genotype-phenotype relationship. © 2014 John Wiley & Sons Ltd.

A lightning strike to the head causing a visual cortex defect with simple and complex visual hallucinations

Science.gov (United States)

Kleiter, Ingo; Luerding, Ralf; Diendorfer, Gerhard; Rek, Helga; Bogdahn, Ulrich; Schalke, Berthold

2009-01-01

The case of a 23-year-old mountaineer who was hit by a lightning strike to the occiput causing a large central visual field defect and bilateral tympanic membrane ruptures is described. Owing to extreme agitation, the patient was sent into a drug-induced coma for 3 days. After extubation, she experienced simple and complex visual hallucinations for several days, but otherwise largely recovered. Neuropsychological tests revealed deficits in fast visual detection tasks and non-verbal learning and indicated a right temporal lobe dysfunction, consistent with a right temporal focus on electroencephalography. At 4 months after the accident, she developed a psychological reaction consisting of nightmares, with reappearance of the complex visual hallucinations and a depressive syndrome. Using the European Cooperation for Lightning Detection network, a meteorological system for lightning surveillance, the exact geographical location and nature of the lightning strike were retrospectively retraced PMID:21734915

Simulation and analysis on ultrasonic testing for the cement grouting defects of the corrugated pipe

Energy Technology Data Exchange (ETDEWEB)

Qingbang, Han; Ling, Chen; Changping, Zhu [Changzhou Key Laboratory of Sensor Networks and Environmental Sensing, College of IOT, Hohai University Changzhou, Jiangsu, 213022 (China)

2014-02-18

The defects exist in the cement grouting process of prestressed corrugated pipe may directly impair the bridge safety. In this paper, sound fields propagation in concrete structures with corrugated pipes and the influence of various different defects are simulated and analyzed using finite element method. The simulation results demonstrate a much complex propagation characteristic due to multiple reflection, refraction and scattering, where the scattering signals caused by metal are very strong, while the signals scattered by an air bubble are weaker. The influence of defect both in time and frequency domain are found through deconvolution treatment. In the time domain, the deconvolution signals correspond to larger defect display a larger head wave amplitude and shorter arrive time than those of smaller defects; in the frequency domain, larger defect also shows a stronger amplitude, lower center frequency and lower cutoff frequency.

Simulation and analysis on ultrasonic testing for the cement grouting defects of the corrugated pipe

International Nuclear Information System (INIS)

Qingbang, Han; Ling, Chen; Changping, Zhu

2014-01-01

The defects exist in the cement grouting process of prestressed corrugated pipe may directly impair the bridge safety. In this paper, sound fields propagation in concrete structures with corrugated pipes and the influence of various different defects are simulated and analyzed using finite element method. The simulation results demonstrate a much complex propagation characteristic due to multiple reflection, refraction and scattering, where the scattering signals caused by metal are very strong, while the signals scattered by an air bubble are weaker. The influence of defect both in time and frequency domain are found through deconvolution treatment. In the time domain, the deconvolution signals correspond to larger defect display a larger head wave amplitude and shorter arrive time than those of smaller defects; in the frequency domain, larger defect also shows a stronger amplitude, lower center frequency and lower cutoff frequency

Birth–death process of local structures in defect turbulence described by the one-dimensional complex Ginzburg–Landau equation

Energy Technology Data Exchange (ETDEWEB)

Uchiyama, Yusuke, E-mail: r1230160@risk.tsukuba.ac.jp; Konno, Hidetoshi

2014-04-01

Defect turbulence described by the one-dimensional complex Ginzburg–Landau equation is investigated and analyzed via a birth–death process of the local structures composed of defects, holes, and modulated amplitude waves (MAWs). All the number statistics of each local structure, in its stationary state, are subjected to Poisson statistics. In addition, the probability density functions of interarrival times of defects, lifetimes of holes, and MAWs show the existence of long-memory and some characteristic time scales caused by zigzag motions of oscillating traveling holes. The corresponding stochastic process for these observations is fully described by a non-Markovian master equation.

Nanoscale interfacial defect shedding in a growing nematic droplet.

Science.gov (United States)

Gurevich, Sebastian; Provatas, Nikolas; Rey, Alejandro

2017-08-01

Interfacial defect shedding is the most recent known mechanism for defect formation in a thermally driven isotropic-to-nematic phase transition. It manifests in nematic-isotropic interfaces going through an anchoring switch. Numerical computations in planar geometry established that a growing nematic droplet can undergo interfacial defect shedding, nucleating interfacial defect structures that shed into the bulk as +1/2 point defects. By extending the study of interfacial defect shedding in a growing nematic droplet to larger length and time scales, and to three dimensions, we unveil an oscillatory growth mode involving shape and anchoring transitions that results in a controllable regular distributions of point defects in planar geometry, and complex structures of disclination lines in three dimensions.

Simulations of defect spin qubits in piezoelectric semiconductors

Science.gov (United States)

Seo, Hosung

In recent years, remarkable advances have been reported in the development of defect spin qubits in semiconductors for solid-state quantum information science and quantum metrology. Promising spin qubits include the nitrogen-vacancy center in diamond, dopants in silicon, and the silicon vacancy and divacancy spins in silicon carbide. In this talk, I will highlight some of our recent efforts devoted to defect spin qubits in piezoelectric wide-gap semiconductors for potential applications in mechanical hybrid quantum systems. In particular, I will describe our recent combined theoretical and experimental study on remarkably robust quantum coherence found in the divancancy qubits in silicon carbide. We used a quantum bath model combined with a cluster expansion method to identify the microscopic mechanisms behind the unusually long coherence times of the divacancy spins in SiC. Our study indicates that developing spin qubits in complex crystals with multiple types of atom is a promising route to realize strongly coherent hybrid quantum systems. I will also discuss progress and challenges in computational design of new spin defects for use as qubits in piezoelectric crystals such as AlN and SiC, including a new defect design concept using large metal ion - vacancy complexes. Our first principles calculations include DFT computations using recently developed self-consistent hybrid density functional theory and large-scale many-body GW theory. This work was supported by the National Science Foundation (NSF) through the University of Chicago MRSEC under Award Number DMR-1420709.

Effective implantation of light emitting centers by plasma immersion ion implantation and focused ion beam methods into nanosized diamond

International Nuclear Information System (INIS)

Himics, L.; Tóth, S.; Veres, M.; Tóth, A.; Koós, M.

2015-01-01

Highlights: • Characteristics of nitrogen implantation of nanodiamond using two low ion energy ion implantation methods were compared. • Formation of complex nitrogen-related defect centers was promoted by subsequent helium implantation and heat treatments. • Depth profiles of the implanted ions and the generated vacancies were determined using SRIM calculations. • The presence of nitrogen impurity was demonstrated by Fourier-transform infrared spectroscopic measurements. • A new nitrogen related band was detected in the photoluminescence spectrum of the implanted samples that was attributed to the N3 color center in nanodiamond. - Abstract: Two different implantation techniques, plasma immersion ion implantation and focused ion beam, were used to introduce nitrogen ions into detonation nanodiamond crystals with the aim to create nitrogen-vacancy related optically active centers of light emission in near UV region. Previously samples were subjected to a defect creation process by helium irradiation in both cases. Heat treatments at different temperatures (750 °C, 450 °C) were applied in order to initiate the formation of nitrogen-vacancy related complex centers and to decrease the sp 2 carbon content formed under different treatments. As a result, a relatively narrow and intensive emission band with fine structure at 2.98, 2.83 and 2.71 eV photon energies was observed in the light emission spectrum. It was assigned to the N3 complex defect center. The formation of this defect center can be expected by taking into account the relatively high dose of implanted nitrogen ions and the overlapped depth distribution of vacancies and nitrogen. The calculated depth profiles distribution for both implanted nitrogen and helium by SRIM simulation support this expectation

Implementing the patient-centered medical home in complex adaptive systems: Becoming a relationship-centered patient-centered medical home.

Science.gov (United States)

Flieger, Signe Peterson

This study explores the implementation experience of nine primary care practices becoming patient-centered medical homes (PCMH) as part of the New Hampshire Citizens Health Initiative Multi-Stakeholder Medical Home Pilot. The purpose of this study is to apply complex adaptive systems theory and relationship-centered organizations theory to explore how nine diverse primary care practices in New Hampshire implemented the PCMH model and to offer insights for how primary care practices can move from a structural PCMH to a relationship-centered PCMH. Eighty-three interviews were conducted with administrative and clinical staff at the nine pilot practices, payers, and conveners of the pilot between November and December 2011. The interviews were transcribed, coded, and analyzed using both a priori and emergent themes. Although there is value in the structural components of the PCMH (e.g., disease registries), these structures are not enough. Becoming a relationship-centered PCMH requires attention to reflection, sensemaking, learning, and collaboration. This can be facilitated by settings aside time for communication and relationship building through structured meetings about PCMH components as well as the implementation process itself. Moreover, team-based care offers a robust opportunity to move beyond the structures to focus on relationships and collaboration. (a) Recognize that PCMH implementation is not a linear process. (b) Implementing the PCMH from a structural perspective is not enough. Although the National Committee for Quality Assurance or other guidelines can offer guidance on the structural components of PCMH implementation, this should serve only as a starting point. (c) During implementation, set aside structured time for reflection and sensemaking. (d) Use team-based care as a cornerstone of transformation. Reflect on team structures and also interactions of the team members. Taking the time to reflect will facilitate greater sensemaking and learning and

Radiation-induced bistable centers with deep levels in silicon n{sup +}–p structures

Energy Technology Data Exchange (ETDEWEB)

Lastovskii, S. B., E-mail: lastov@ifttp.bas-net.by [Scientific and Practical Materials Research Center of the National Academy of Sciences of Belarus (Belarus); Markevich, V. P. [Manchester University, Photon Science Institute (United Kingdom); Yakushevich, H. S.; Murin, L. I. [Scientific and Practical Materials Research Center of the National Academy of Sciences of Belarus (Belarus); Krylov, V. P. [Vladimir State University (Russian Federation)

2016-06-15

The method of deep level transient spectroscopy is used to study electrically active defects in p-type silicon crystals irradiated with MeV electrons and α particles. A new radiation-induced defect with the properties of bistable centers is determined and studied. After keeping the irradiated samples at room temperature for a long time or after their short-time annealing at T ∼ 370 K, this defect does not display any electrical activity in p-type silicon. However, as a result of the subsequent injection of minority charge carriers, this center transforms into the metastable configuration with deep levels located at E{sub V} + 0.45 and E{sub V} + 0.54 eV. The reverse transition to the main configuration occurs in the temperature range of 50–100°C and is characterized by the activation energy ∼1.25 eV and a frequency factor of ∼5 × 10{sup 15} s{sup –1}. The determined defect is thermally stable at temperatures as high as T ∼ 450 K. It is assumed that this defect can either be a complex of an intrinsic interstitial silicon atom with an interstitial carbon atom or a complex consisting of an intrinsic interstitial silicon atom with an interstitial boron atom.

Combined Respiratory Chain Deficiency and UQCC2 Mutations in Neonatal Encephalomyopathy: Defective Supercomplex Assembly in Complex III Deficiencies

Directory of Open Access Journals (Sweden)

René G. Feichtinger

2017-01-01

Full Text Available Vertebrate respiratory chain complex III consists of eleven subunits. Mutations in five subunits either mitochondrial (MT-CYB or nuclear (CYC1, UQCRC2, UQCRB, and UQCRQ encoded have been reported. Defects in five further factors for assembly (TTC19, UQCC2, and UQCC3 or iron-sulphur cluster loading (BCS1L and LYRM7 cause complex III deficiency. Here, we report a second patient with UQCC2 deficiency. This girl was born prematurely; pregnancy was complicated by intrauterine growth retardation and oligohydramnios. She presented with respiratory distress syndrome, developed epileptic seizures progressing to status epilepticus, and died at day 33. She had profound lactic acidosis and elevated urinary pyruvate. Exome sequencing revealed two homozygous missense variants in UQCC2, leading to a severe reduction of UQCC2 protein. Deficiency of complexes I and III was found enzymatically and on the protein level. A review of the literature on genetically distinct complex III defects revealed that, except TTC19 deficiency, the biochemical pattern was very often a combined respiratory chain deficiency. Besides complex III, typically, complex I was decreased, in some cases complex IV. In accordance with previous observations, the presence of assembled complex III is required for the stability or assembly of complexes I and IV, which might be related to respirasome/supercomplex formation.

Defect study of Zn-doped p-type gallium antimonide using positron lifetime spectroscopy

International Nuclear Information System (INIS)

Ling, C. C.; Fung, S.; Beling, C. D.; Huimin, Weng

2001-01-01

Defects in p-type Zn-doped liquid-encapsulated Czochralski--grown GaSb were studied by the positron lifetime technique. The lifetime measurements were performed on the as-grown sample at temperature varying from 15 K to 297 K. A positron trapping center having a characteristic lifetime of 317 ps was identified as the neutral V Ga -related defect. Its concentration in the as-grown sample was found to be in the range of 10 17 --10 18 cm -3 . At an annealing temperature of 300 o C, the V Ga -related defect began annealing out and a new defect capable of trapping positrons was formed. This newly formed defect, having a lifetime value of 379 ps, is attributed to a vacancy--Zn-defect complex. This defect started annealing out at a temperature of 580 o C. A positron shallow trap having binding energy and concentration of 75 meV and 10 18 cm -3 , respectively, was also observed in the as-grown sample. This shallow trap is attributed to positrons forming hydrogenlike Rydberg states with the ionized dopant acceptor Zn

Energy Frontier Research Center, Center for Materials Science of Nuclear Fuels

Energy Technology Data Exchange (ETDEWEB)

Todd R. Allen, Director

2011-04-01

The Office of Science, Basic Energy Sciences, has funded the INL as one of the Energy Frontier Research Centers in the area of material science of nuclear fuels. This document is the required annual report to the Office of Science that outlines the accomplishments for the period of May 2010 through April 2011. The aim of the Center for Material Science of Nuclear Fuels (CMSNF) is to establish the foundation for predictive understanding of the effects of irradiation-induced defects on thermal transport in oxide nuclear fuels. The science driver of the center’s investigation is to understand how complex defect and microstructures affect phonon mediated thermal transport in UO2, and achieve this understanding for the particular case of irradiation-induced defects and microstructures. The center’s research thus includes modeling and measurement of thermal transport in oxide fuels with different levels of impurities, lattice disorder and irradiation-induced microstructure, as well as theoretical and experimental investigation of the evolution of disorder, stoichiometry and microstructure in nuclear fuel under irradiation. With the premise that thermal transport in irradiated UO2 is a phonon-mediated energy transport process in a crystalline material with defects and microstructure, a step-by-step approach will be utilized to understand the effects of types of defects and microstructures on the collective phonon dynamics in irradiated UO2. Our efforts under the thermal transport thrust involved both measurement of diffusive phonon transport (an approach that integrates over the entire phonon spectrum) and spectroscopic measurements of phonon attenuation/lifetime and phonon dispersion. Our distinct experimental efforts dovetail with our modeling effort involving atomistic simulation of phonon transport and prediction of lattice thermal conductivity using the Boltzmann transport framework.

X-ray and optical study on point defect formation and interaction under irradiation adn doping of KCl

Energy Technology Data Exchange (ETDEWEB)

Braude, I S; Rogozyanskaya, L M [AN Ukrainskoj SSR, Kharkov. Fiziko-Tekhnicheskij Inst. Nizkikh Temperatur

1978-08-01

Optical and X-ray diffuse scattering methods have been applied to investigate structural changes, taking place in KCl crystals during irradiation with ..gamma..-quanta and doping with barium. It is shown that ..gamma..-irradiation of ''pure'' and doped KCl crystals mainly leads to formation of F-centers and spherical vacancy complexes. F-center concentration in irradiated addition crystals (3x10/sup -6/) has turned out to be 25% lower, than in irradiated pure ones (4x10/sup -6/), which is connected with interaction of radiation and addition defects. The type of defects, causing assymetry in the distribution of diffuse scattering has been determined. Appearance of scattering ability modulation over direction < 100 > during irradiation of KCl pure crystals has been found. Critical radius of spherical complexes formed during irradiation has been estimated, it appeared to be 2.5 a, where a is a lattice period.

Electroreduction of CO2 Catalyzed by a Heterogenized Zn–Porphyrin Complex with a Redox-Innocent Metal Center

Science.gov (United States)

2017-01-01

Transition-metal-based molecular complexes are a class of catalyst materials for electrochemical CO2 reduction to CO that can be rationally designed to deliver high catalytic performance. One common mechanistic feature of these electrocatalysts developed thus far is an electrogenerated reduced metal center associated with catalytic CO2 reduction. Here we report a heterogenized zinc–porphyrin complex (zinc(II) 5,10,15,20-tetramesitylporphyrin) as an electrocatalyst that delivers a turnover frequency as high as 14.4 site–1 s–1 and a Faradaic efficiency as high as 95% for CO2 electroreduction to CO at −1.7 V vs the standard hydrogen electrode in an organic/water mixed electrolyte. While the Zn center is critical to the observed catalysis, in situ and operando X-ray absorption spectroscopic studies reveal that it is redox-innocent throughout the potential range. Cyclic voltammetry indicates that the porphyrin ligand may act as a redox mediator. Chemical reduction of the zinc–porphyrin complex further confirms that the reduction is ligand-based and the reduced species can react with CO2. This represents the first example of a transition-metal complex for CO2 electroreduction catalysis with its metal center being redox-innocent under working conditions. PMID:28852698

Stepladder Reconstructive Options in Post-Ablative Complex Surgical Defects in the Head and Neck

International Nuclear Information System (INIS)

EL MARAKBY, H.H.; NAGUIB, Sh.F.; EL-SAWY, A.F.; AMIN, A.A.

2008-01-01

Background: Reconstruction of head and neck defects can pose many challenges to the reconstructive head and neck surgeon. Achieving the best cosmetic and functional results without compromising the safety of oncologic surgery are the primary reconstructive goals. Speech and articulation are particularly important in oral reconstructive procedures. In addition, preservation of the integrity and function of the donor sites should always be considered in all reconstructive procedures. Aim of the Study: The aim of the study is to evaluate different reconstructive options in complex defects of the head and neck region after resection of malignant tumours. The feasibility of the reconstructive ladder starting from simple techniques such as local flaps and skin grafts up to free flaps will be assessed. Patients and Methods: In this study we evaluated different reconstructive procedures used in 50 patients with complex head and neck defects undertaken at the department of surgery at the National Cancer Institute between July 2003 and December 2007. Results: The average age of patients was 52 years and the range was 26-67 years. Most of the tumours were either squamous cell carcinoma (74%) or Basal cell carcinoma (20%). Tumour sites included the nose (6%), lip (10%), cheek (12%) scalp (6%) as well as mucosal defects of the oral cavity (40%) and the hypopharynx (20%). We used local flaps and skin grafts in reconstruction in 36% of cases and pedicled flaps in 32% while free flaps were used in 32% of cases. Complications occurred in 32% of patients of which total flaps loss constituted 6% and partial flap loss 4%. Minor complications such as oro-cutaneous fistulae, wound infection, seroma and haematoma were noticed in 22% and all of them were treated conservatively. The final functional and aesthetic results were satisfactory in 60% of cases while poor results were encountered in patients who suffered some degree of flap loss.

Defect of the Eyelids.

Science.gov (United States)

Lu, Guanning Nina; Pelton, Ron W; Humphrey, Clinton D; Kriet, John David

2017-08-01

Eyelid defects disrupt the complex natural form and function of the eyelids and present a surgical challenge. Detailed knowledge of eyelid anatomy is essential in evaluating a defect and composing a reconstructive plan. Numerous reconstructive techniques have been described, including primary closure, grafting, and a variety of local flaps. This article describes an updated reconstructive ladder for eyelid defects that can be used in various permutations to solve most eyelid defects. Copyright © 2017 Elsevier Inc. All rights reserved.

Dynamics of Defects and Dopants in Complex Systems: Si and Oxide Surfaces and Interfaces

Science.gov (United States)

Kirichenko, Taras; Yu, Decai; Banarjee, Sanjay; Hwang, Gyeong

2004-10-01

Fabrication of forthcoming nanometer scale electronic devices faces many difficulties including formation of extremely shallow and highly doped junctions. At present, ultra-low-energy ion implantation followed by high-temperature thermal annealing is most widely used to fabricate such ultra-shallow junctions. In the process, a great challenge lies in achieving precise control of redistribution and electrical activation of dopant impurities. Native defects (such as vacancies and interstitials) generated during implantation are known to be mainly responsible for the TED and also influence significantly the electrical activation/deactivation. Defect-dopant dynamics is rather well understood in crystalline Si and SiO2. However, little is known about their diffusion and annihilation (or precipitation) at the surfaces and interfaces, despite its growing importance in determining junction profiles as device dimensions get smaller. In this talk, we will present our density functional theory calculation results on the atomic and electronic structure and dynamical behavior of native defects and dopant-defect complexes in disordered/strained Si and oxide systems, such as i) clean and absorbent-modified Si(100) surface and subsurface layers, ii) amorphous-crystalline Si interfaces and iii) amorphous SiO2/Si interfaces. The fundamental understanding and data is essential in developing a comprehensive kinetic model for junction formation, which would contribute greatly in improving current process technologies.

Intrinsic and extrinsic defects in a family of coal-derived graphene quantum dots

Science.gov (United States)

Singamaneni, Srinivasa Rao; van Tol, Johan; Ye, Ruquan; Tour, James M.

2015-11-01

In this letter, we report on the high frequency (239.2 and 336 GHz) electron spin resonance (ESR) studies performed on graphene quantum dots (GQDs), prepared through a wet chemistry route from three types of coal: (a) bituminous, (b) anthracite, and (c) coke; and from non-coal derived GQDs. The microwave frequency-, power-, and temperature-dependent ESR spectra coupled with computer-aided simulations reveal four distinct magnetic defect centers. In bituminous- and anthracite-derived GQDs, we have identified two of them as intrinsic carbon-centered magnetic defect centers (a broad signal of peak to peak width = 697 (10-4 T), g = 2.0023; and a narrow signal of peak to peak width = 60 (10-4 T), g = 2.003). The third defect center is Mn2+ (6S5/2, 3d5) (signal width = 61 (10-4 T), g = 2.0023, Aiso = 93(10-4 T)), and the fourth defect is identified as Cu2+ (2D5/2, 3d9) (g⊥ = 2.048 and g‖ = 2.279), previously undetected. Coke-derived and non-coal derived GQDs show Mn2+ and two-carbon related signals, and no Cu2+ signal. The extrinsic impurities most likely originate from the starting coal. Furthermore, Raman, photoluminescence, and ESR measurements detected no noticeable changes in the properties of the bituminous GQDs after one year. This study highlights the importance of employing high frequency ESR spectroscopy in identifying the (magnetic) defects, which are roadblocks for spin relaxation times of graphene-based materials. These defects would not have been possible to probe by other spin transport measurements.

Defect-impurity interactions in ion-implanted metals

International Nuclear Information System (INIS)

Turos, A.

1986-01-01

An overview of defect-impurity interactions in metals is presented. When point defects become mobile they migrate towards the sinks and on the way can be captured by impurity atoms forming stable associations so-called complexes. In some metallic systems complexes can also be formed athermally during ion implantation by trapping point defects already in the collision cascade. An association of a point defect with an impurity atom leads to its displacement from the lattice site. The structure and stability of complexes are strongly temperature dependent. With increasing temperature they dissociate or grow by multiple defect trapping. The appearance of freely migrating point defects at elevated temperatures, due to ion bombardment or thermal annealing, causes via coupling with defect fluxes, important impurity redistribution. Because of the sensitivity of many metal-in-metal implanted systems to radiation damage the understanding of this processes is essential for a proper interpretation of the lattice occupancy measurements and the optimization of implantation conditions. (author)

Synthetic Defects for Vibrothermography

Science.gov (United States)

Renshaw, Jeremy; Holland, Stephen D.; Thompson, R. Bruce; Eisenmann, David J.

2010-02-01

Synthetic defects are an important tool used for characterizing the performance of nondestructive evaluation techniques. Viscous material-filled synthetic defects were developed for use in vibrothermography (also known as sonic IR) as a tool to improve inspection accuracy and reliability. This paper describes how the heat-generation response of these VMF synthetic defects is similar to the response of real defects. It also shows how VMF defects can be applied to improve inspection accuracy for complex industrial parts and presents a study of their application in an aircraft engine stator vane.

Ectopic germinal center and megalin defect in primary Sjogren syndrome with renal Fanconi syndrome.

Science.gov (United States)

Wang, Jing; Wen, Yubing; Zhou, Mengyu; Shi, Xiaoxiao; Jiang, Lanping; Li, Mingxi; Yu, Yang; Li, Xuemei; Li, Xuewang; Zhang, Wen; Lundquist, Andrew L; Chen, Limeng

2017-06-02

This study reports the clinical and pathological features of 12 cases of primary Sjogren syndrome (pSS) with renal involvement presenting with proximal tubular dysfunction in a single center, and investigates the possible correlation of ectopic germinal center formation and megalin/cubilin down-expression. Clinical and pathological records were reviewed. Immunohistochemistry was carried out to detect megalin, cubilin, CD21 and IL-17 expression. Patients presented with different degrees of proximal renal tubule lesion and decreased estimated glomerular filtration rate (eGFR). Renal biopsy revealed tubulointerstitial nephritis, with tubular epithelial cell degeneration, tubular atrophy, interstitial inflammation and focal fibrosis. Immunohistochemistry revealed decreased expression of megalin and cubilin, two important multiligand protein receptors on the brush border of proximal tubular epithelial cells. IL-17 secreted by Th17 subtype effector T cells was diffusely detected in the renal proximal tubule, with a negative correlation of IL-17 and megalin expression. In addition, ectopic germinal centers characterized by CD21 + follicular dendritic cells were present in the renal interstitium. In patients with a decreased eGFR, treatment with 4 weeks of glucocorticoid therapy resulted in an improved eGFR in 75% of patients. We report 12 cases of pSS characterized by Fanconi syndrome. The decreased megalin and cubilin expression may contribute to the proximal tubular reabsorption defect, possibly secondary to Th17 infiltration and formation of ectopic germinal centers.

Recombination centers and electrical characteristics in silicon power p-i-n diodes irradiated with high energy electrons

International Nuclear Information System (INIS)

Fuochi, P.G.; Martelli, A.; Passerini, B.; Zambelli, M.

1988-01-01

Recombination centers introduced by irradiation with 12 MeV electrons in large area silicon diodes with p-i-n structure are studied with the Deep Level Transient Spectroscopy technique (DLTS). The effects of these levels on the electrical characteristics of the devices are related to their position Esub(t) in the silicon forbidden gap, their concentration and their electron capture cross section. Changes of defect configuration during an annealing process at 360 0 C have been observed and a detailed analysis of the DLTS spectra has shown a complex defect pattern. Four major recombination centers have been identified: Esub(c) - Esub(t) = 0.17 eV, Esub(c) - Esub(t) = 0.19 eV, Esub(c) -Esub(t) 0.31 eV, Esub(c) - Esub(t) = 0.39 eV, where Esub(c) is the energy corresponding to the lower limit of the conduction band. The first energy level, known as A-center, is the dominant recombination level controlling the minority carrier lifetime after room temperature irradiation. As the annealing proceeds the center at Esub(c) - Esub(t) = 0.31 eV becomes the dominant one. The complex structure of the centers has been studied and demonstrated with the aid of proper modelling implemented on a set of numerical simulation tools. In this way it has been possible to analyze more accurately the defect kinetics during annealing. The study of the defect behaviour during the annealing process has resulted in an improved application of electron irradiation as a standard production technique in the manufacturing process of high power devices. (author)

Impact of interstitial iron on the study of meta-stable B-O defects in Czochralski silicon: Further evidence of a single defect

Science.gov (United States)

Kim, Moonyong; Chen, Daniel; Abbott, Malcolm; Nampalli, Nitin; Wenham, Stuart; Stefani, Bruno; Hallam, Brett

2018-04-01

We explore the influence of interstitial iron (Fei) on lifetime spectroscopy of boron-oxygen (B-O) related degradation in p-type Czochralski silicon. Theoretical and experimental evidence presented in this study indicate that iron-boron pair (Fe-B) related reactions could have influenced several key experimental results used to derive theories on the fundamental properties of the B-O defect. Firstly, the presence of Fei can account for higher apparent capture cross-section ratios (k) of approximately 100 observed in previous studies during early stages of B-O related degradation. Secondly, the association of Fe-B pairs can explain the initial stage of a two-stage recovery of carrier lifetime with dark annealing after partial degradation. Thirdly, Fei can result in high apparent k values after the permanent deactivation of B-O defects. Subsequently, we show that a single k value can describe the recombination properties associated with B-O defects throughout degradation, that the recovery during dark annealing occurs with a single-stage, and both the fast- and slow-stage B-O related degradation can be permanently deactivated during illuminated annealing. Accounting for the recombination activity of Fei provides further evidence that the B-O defect is a single defect, rather than two separate defects normally attributed to fast-forming recombination centers and slow-forming recombination centers. Implications of this finding for the nature of the B-O defect are also discussed.

Introduction and recovery of point defects in electron-irradiated ZnO

International Nuclear Information System (INIS)

Tuomisto, F.; Saarinen, K.; Look, D.C.; Farlow, G.C.

2005-01-01

We have used positron annihilation spectroscopy to study the introduction and recovery of point defects in electron-irradiated n-type ZnO. The irradiation (E el =2 MeV, fluence 6x10 17 cm -2 ) was performed at room temperature, and isochronal annealings were performed from 300 to 600 K. In addition, monochromatic illumination of the samples during low-temperature positron measurements was used in identification of the defects. We distinguish two kinds of vacancy defects: the Zn and O vacancies, which are either isolated or belong to defect complexes. In addition, we observe negative-ion-type defects, which are attributed to O interstitials or O antisites. The Zn vacancies and negative ions act as compensating centers and are introduced at a concentration [V Zn ]≅c ion ≅2x10 16 cm -3 . The O vacancies are introduced at a 10-times-larger concentration [V O ]≅3x10 17 cm -3 and are suggested to be isolated. The O vacancies are observed as neutral at low temperatures, and an ionization energy of 100 meV could be fitted with the help of temperature-dependent Hall data, thus indicating their deep donor character. The irradiation-induced defects fully recover after the annealing at 600 K, in good agreement with electrical measurements. The Zn vacancies recover in two separate stages, indicating that the Zn vacancies are parts of two different defect complexes. The O vacancies anneal simultaneously with the Zn vacancies at the later stage, with an activation energy of E V,O m =1.8±0.1 eV. The negative ions anneal out between the two annealing stages of the vacancies

CLASSIFICATION AND COMPLEX STATE VALUE OF SHOPPING CENTERS: PROJECT-ORIENTED APPROACH

Directory of Open Access Journals (Sweden)

Юрій Павлович РАК

2016-02-01

Full Text Available Was done the analysis of projects objects of trade and entertainment centers from the perspective of improving the life safety and is proposed the definition of "Trade and entertainment center", "Trade and entertainment center" and "Complex value of trade and entertainment center." A classification of shopping centers on the classification criteria and the criteria are characterized by increased security status and attractiveness of their operation. The classification of trade and entertainment centers on the criteria of classification features were made. It characterizes the security situation and will increase the attractiveness of their operation. In the nearest future the most secure and modern TEC will be those buildings who will have unique qualities such as safety systems, excellent customer service, and thus by a high level of trust (the client to the mall. The important role will play those TEC, who have clearly formed value oriented project management, including communication values using innovative methods and models. Trade and entertainment centers as an organization are included in the complex process of interaction management. They being both as an enterprise that serves the public and satisfying a great range of his interests and architectural site, which is leased and increases the business attractiveness of the district of TEC location. This duality of the essence of TEC center makes difficult to assess the effectiveness of its security.

Superficial temporal artery flap for reconstruction of complex facial defects: A new algorithm

Directory of Open Access Journals (Sweden)

Tarek M. Elbanoby

2018-03-01

Full Text Available Background A variety of island flaps can be based on the superficial temporal artery with variable tissue composition. They can be used for defect reconstruction, cavity resurfacing, facial hair restoration, or contracture release. Methods Seventy-two patients underwent facial reconstruction using a superficial temporal artery island flap from October 2010 to October 2014. The defects had various etiologies, including trauma, burns, tumors, exposed hardware, and congenital causes. We classified the patients by indication into 5 groups: cavity resurfacing, contracture release, facial hair restoration, skin coverage, and combined. The demographic data of the patients, defect characteristics, operative procedures, postoperative results, and complications were retrospectively documented. The follow-up period ranged from 24 to 54 months. Results A total of 24 females and 48 males were included in this study. The mean age of the patients was 33.7±15.6 years. The flaps were used for contracture release in 13 cases, cavity resurfacing in 10 cases, skin coverage in 17 cases, facial hair restoration in 19 cases, and combined defects in 13 cases. No major complications were reported. Conclusion: Based on our experiences with the use of superficial temporal artery island flaps, we have developed a detailed approach for the optimal management of patients with composite facial defects. The aim of this article is to provide the reader with a systematic algorithm to use for such patients.

A novel malformation complex of bilateral and symmetric preaxial radial ray-thumb aplasia and lower limb defects with minimal facial dysmorphic features: a case report and literature review.

Science.gov (United States)

Al Kaissi, Ali; Klaushofer, Klaus; Krebs, Alexander; Grill, Franz

2008-10-24

Radial hemimelia is a congenital abnormality characterised by the partial or complete absence of the radius. The longitudinal hemimelia indicates the absence of one or more bones along the preaxial (medial) or postaxial (lateral) side of the limb. Preaxial limb defects occurred more frequently with a combination of microtia, esophageal atresia, anorectal atresia, heart defects, unilateral kidney dysgenesis, and some axial skeletal defects. Postaxial acrofacial dysostoses are characterised by distinctive facies and postaxial limb deficiencies, involving the 5th finger, metacarpal/ulnar/fibular/and metatarsal. The patient, an 8-year-old-boy with minimal craniofacial dysmorphic features but with profound upper limb defects of bilateral and symmetrical absence of the radius and the thumbs respectively. In addition, there was a unilateral tibio-fibular hypoplasia (hemimelia) associated with hypoplasia of the terminal phalanges and malsegmentation of the upper thoracic vertebrae, causing effectively the development of thoracic kyphosis. In the typical form of the preaxial acrofacial dysostosis, there are aberrations in the development of the first and second branchial arches and limb buds. The craniofacial dysmorphic features are characteristic such as micrognathia, zygomatic hypoplasia, cleft palate, and preaxial limb defects. Nager and de Reynier in 1948, who used the term acrofacial dysostosis (AFD) to distinguish the condition from mandibulofacial dysostosis. Neither the facial features nor the limb defects in our present patient appear to be absolutely typical with the previously reported cases of AFD. Our patient expands the phenotype of syndromic preaxial limb malformation complex. He might represent a new syndromic entity of mild naso-maxillary malformation in connection with axial and extra-axial malformation complex.

Phase Defects as a Measure of Disorder in Traveling-Wave Convection

International Nuclear Information System (INIS)

La Porta, A.; Surko, C.M.

1996-01-01

Spatiotemporal disorder is studied in traveling-wave convection in an ethanol-water mixture. A technique for calculating the complex order parameter of the pattern is described, and the identification of phase defects is demonstrated. Point defects, domain boundaries, and standing wave patterns are shown to produce unique defect structures. The transition from a disordered state to a more ordered pattern is described in terms of the dynamics of defects and their statistics. copyright 1996 The American Physical Society

Intrinsic and extrinsic defects in a family of coal-derived graphene quantum dots

Energy Technology Data Exchange (ETDEWEB)

Singamaneni, Srinivasa Rao, E-mail: ssingam@ncsu.edu, E-mail: tour@rice.edu [Materials Science Division, Army Research Office, Research Triangle Park, North Carolina 27709 (United States); Department of Material Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Tol, Johan van [National High Magnetic Field Laboratory, Florida State University, 1800 E. Paul Dirac Drive, Tallahassee, Florida 32310 (United States); Ye, Ruquan [Department of Chemistry, Rice University, MS-222, 6100 Main Street, Houston, Texas 77005 (United States); Tour, James M., E-mail: ssingam@ncsu.edu, E-mail: tour@rice.edu [Department of Chemistry, Rice University, MS-222, 6100 Main Street, Houston, Texas 77005 (United States); Department of Materials Science and NanoEngineering, Rice University, MS-222, 6100 Main Street, Houston, Texas 77005 (United States); Smalley Institute for Nanoscale Science and Technology, Rice University, MS-222, 6100 Main Street, Houston, Texas 77005 (United States)

2015-11-23

In this letter, we report on the high frequency (239.2 and 336 GHz) electron spin resonance (ESR) studies performed on graphene quantum dots (GQDs), prepared through a wet chemistry route from three types of coal: (a) bituminous, (b) anthracite, and (c) coke; and from non-coal derived GQDs. The microwave frequency-, power-, and temperature-dependent ESR spectra coupled with computer-aided simulations reveal four distinct magnetic defect centers. In bituminous- and anthracite-derived GQDs, we have identified two of them as intrinsic carbon-centered magnetic defect centers (a broad signal of peak to peak width = 697 (10{sup −4} T), g = 2.0023; and a narrow signal of peak to peak width = 60 (10{sup −4} T), g = 2.003). The third defect center is Mn{sup 2+} ({sup 6}S{sub 5/2}, 3d{sup 5}) (signal width = 61 (10{sup −4} T), g = 2.0023, A{sub iso} = 93(10{sup −4} T)), and the fourth defect is identified as Cu{sup 2+} ({sup 2}D{sub 5/2}, 3d{sup 9}) (g{sub ⊥} = 2.048 and g{sub ‖} = 2.279), previously undetected. Coke-derived and non-coal derived GQDs show Mn{sup 2+} and two-carbon related signals, and no Cu{sup 2+} signal. The extrinsic impurities most likely originate from the starting coal. Furthermore, Raman, photoluminescence, and ESR measurements detected no noticeable changes in the properties of the bituminous GQDs after one year. This study highlights the importance of employing high frequency ESR spectroscopy in identifying the (magnetic) defects, which are roadblocks for spin relaxation times of graphene-based materials. These defects would not have been possible to probe by other spin transport measurements.

[TVT (transvaginal mesh) surgical method for complex resolution of pelvic floor defects].

Science.gov (United States)

Adamík, Z

2006-01-01

Assessment of the effects of a new surgical method for complex resolution of pelvic floor defects. Case study. Department of Obstetrics and Gynaecology, Bata Hospital, Zlín. We evaluated the procedures and results of the new TVM (transvaginal mesh) surgical method which we used in a group of 12 patients. Ten patients had vaginal prolapse following vaginal hysterectomy and in two cases there was uterine prolapse and vaginal prolapse. Only in one case there was a small protrusion in the range of 0.5 cm which we resolved by removal of the penetrated section. The resulting anatomic effect was very good in all the cases.

Vacancy defects and defect clusters in alkali metal ion-doped MgO nanocrystallites studied by positron annihilation and photoluminescence spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Sellaiyan, S.; Uedono, A. [University of Tsukuba, Division of Applied Physics, Tsukuba, Ibaraki (Japan); Sivaji, K.; Janet Priscilla, S. [University of Madras, Department of Nuclear Physics, Chennai (India); Sivasankari, J. [Anna University, Department of Physics, Chennai (India); Selvalakshmi, T. [National Institute of Technology, Nanomaterials Laboratory, Department of Physics, Tiruchirappalli (India)

2016-10-15

Pure and alkali metal ion (Li, Na, and K)-doped MgO nanocrystallites synthesized by solution combustion technique have been studied by positron lifetime and Doppler broadening spectroscopy methods. Positron lifetime analysis exhibits four characteristic lifetime components for all the samples. Doping reduces the Mg vacancy after annealing to 800 C. It was observed that Li ion migrates to the vacancy site to recover Mg vacancy-type defects, reducing cluster vacancies and micropores. For Na- and K-doped MgO, the aforementioned defects are reduced and immobile at 800 C. Coincidence Doppler broadening studies show the positron trapping sites as vacancy clusters. The decrease in the S parameter is due to the particle growth and reduction in the defect concentration at 800 C. Photoluminescence study shows an emission peak at 445 nm and 498 nm, associated with F{sub 2} {sup 2+} and recombination of higher-order vacancy complexes. Further, annealing process is likely to dissociate F{sub 2} {sup 2+} to F{sup +} and this F{sup +} is converted into F centers at 416 nm. (orig.)

Vacancy defects and defect clusters in alkali metal ion-doped MgO nanocrystallites studied by positron annihilation and photoluminescence spectroscopy

Science.gov (United States)

Sellaiyan, S.; Uedono, A.; Sivaji, K.; Janet Priscilla, S.; Sivasankari, J.; Selvalakshmi, T.

2016-10-01

Pure and alkali metal ion (Li, Na, and K)-doped MgO nanocrystallites synthesized by solution combustion technique have been studied by positron lifetime and Doppler broadening spectroscopy methods. Positron lifetime analysis exhibits four characteristic lifetime components for all the samples. Doping reduces the Mg vacancy after annealing to 800 °C. It was observed that Li ion migrates to the vacancy site to recover Mg vacancy-type defects, reducing cluster vacancies and micropores. For Na- and K-doped MgO, the aforementioned defects are reduced and immobile at 800 °C. Coincidence Doppler broadening studies show the positron trapping sites as vacancy clusters. The decrease in the S parameter is due to the particle growth and reduction in the defect concentration at 800 °C. Photoluminescence study shows an emission peak at 445 nm and 498 nm, associated with F2 2+ and recombination of higher-order vacancy complexes. Further, annealing process is likely to dissociate F2 2+ to F+ and this F+ is converted into F centers at 416 nm.

Vacancy defects and defect clusters in alkali metal ion-doped MgO nanocrystallites studied by positron annihilation and photoluminescence spectroscopy

International Nuclear Information System (INIS)

Sellaiyan, S.; Uedono, A.; Sivaji, K.; Janet Priscilla, S.; Sivasankari, J.; Selvalakshmi, T.

2016-01-01

Pure and alkali metal ion (Li, Na, and K)-doped MgO nanocrystallites synthesized by solution combustion technique have been studied by positron lifetime and Doppler broadening spectroscopy methods. Positron lifetime analysis exhibits four characteristic lifetime components for all the samples. Doping reduces the Mg vacancy after annealing to 800 C. It was observed that Li ion migrates to the vacancy site to recover Mg vacancy-type defects, reducing cluster vacancies and micropores. For Na- and K-doped MgO, the aforementioned defects are reduced and immobile at 800 C. Coincidence Doppler broadening studies show the positron trapping sites as vacancy clusters. The decrease in the S parameter is due to the particle growth and reduction in the defect concentration at 800 C. Photoluminescence study shows an emission peak at 445 nm and 498 nm, associated with F_2 "2"+ and recombination of higher-order vacancy complexes. Further, annealing process is likely to dissociate F_2 "2"+ to F"+ and this F"+ is converted into F centers at 416 nm. (orig.)

Characterizing complexity in socio-technical systems: a case study of a SAMU Medical Regulation Center.

Science.gov (United States)

Righi, Angela Weber; Wachs, Priscila; Saurin, Tarcísio Abreu

2012-01-01

Complexity theory has been adopted by a number of studies as a benchmark to investigate the performance of socio-technical systems, especially those that are characterized by relevant cognitive work. However, there is little guidance on how to assess, systematically, the extent to which a system is complex. The main objective of this study is to carry out a systematic analysis of a SAMU (Mobile Emergency Medical Service) Medical Regulation Center in Brazil, based on the core characteristics of complex systems presented by previous studies. The assessment was based on direct observations and nine interviews: three of them with regulator of emergencies medical doctor, three with radio operators and three with telephone attendants. The results indicated that, to a great extent, the core characteristics of complexity are magnified) due to basic shortcomings in the design of the work system. Thus, some recommendations are put forward with a view to reducing unnecessary complexity that hinders the performance of the socio-technical system.

Defects in dilute nitrides

International Nuclear Information System (INIS)

Chen, W.M.; Buyanova, I.A.; Tu, C.W.; Yonezu, H.

2005-01-01

We provide a brief review our recent results from optically detected magnetic resonance studies of grown-in non-radiative defects in dilute nitrides, i.e. Ga(In)NAs and Ga(Al,In)NP. Defect complexes involving intrinsic defects such as As Ga antisites and Ga i self interstitials were positively identified.Effects of growth conditions, chemical compositions and post-growth treatments on formation of the defects are closely examined. These grown-in defects are shown to play an important role in non-radiative carrier recombination and thus in degrading optical quality of the alloys, harmful to performance of potential optoelectronic and photonic devices based on these dilute nitrides. (author)

A fast button surface defects detection method based on convolutional neural network

Science.gov (United States)

Liu, Lizhe; Cao, Danhua; Wu, Songlin; Wu, Yubin; Wei, Taoran

2018-01-01

Considering the complexity of the button surface texture and the variety of buttons and defects, we propose a fast visual method for button surface defect detection, based on convolutional neural network (CNN). CNN has the ability to extract the essential features by training, avoiding designing complex feature operators adapted to different kinds of buttons, textures and defects. Firstly, we obtain the normalized button region and then use HOG-SVM method to identify the front and back side of the button. Finally, a convolutional neural network is developed to recognize the defects. Aiming at detecting the subtle defects, we propose a network structure with multiple feature channels input. To deal with the defects of different scales, we take a strategy of multi-scale image block detection. The experimental results show that our method is valid for a variety of buttons and able to recognize all kinds of defects that have occurred, including dent, crack, stain, hole, wrong paint and uneven. The detection rate exceeds 96%, which is much better than traditional methods based on SVM and methods based on template match. Our method can reach the speed of 5 fps on DSP based smart camera with 600 MHz frequency.

EUV actinic defect inspection and defect printability at the sub-32 nm half pitch

Energy Technology Data Exchange (ETDEWEB)

Huh, Sungmin; Kearney, Patrick; Wurm, Stefan; Goodwin, Frank; Han, Hakseung; Goldberg, Kenneth; Mochi, Iacopp; Gullikson, Eric M.

2009-08-01

Extreme ultraviolet (EUV) mask blanks with embedded phase defects were inspected with a reticle actinic inspection tool (AIT) and the Lasertec M7360. The Lasertec M7360, operated at SEMA TECH's Mask Blank Development Center (MBDC) in Albany, NY, has a sensitivity to multilayer defects down to 40-45 nm, which is not likely sufficient for mask blank development below the 32 nm half-pitch node. Phase defect printability was simulated to calculate the required defect sensitivity for a next generation blank inspection tool to support reticle development for the sub-32 nm half-pitch technology node. Defect mitigation technology is proposed to take advantage of mask blanks with some defects. This technology will reduce the cost of ownership of EUV mask blanks. This paper will also discuss the kind of infrastructure that will be required for the development and mass production stages.

Maxillectomy defects: a suggested classification scheme.

Science.gov (United States)

Akinmoladun, V I; Dosumu, O O; Olusanya, A A; Ikusika, O F

2013-06-01

The term "maxillectomy" has been used to describe a variety of surgical procedures for a spectrum of diseases involving a diverse anatomical site. Hence, classifications of maxillectomy defects have often made communication difficult. This article highlights this problem, emphasises the need for a uniform system of classification and suggests a classification system which is simple and comprehensive. Articles related to this subject, especially those with specified classifications of maxillary surgical defects were sourced from the internet through Google, Scopus and PubMed using the search terms maxillectomy defects classification. A manual search through available literature was also done. The review of the materials revealed many classifications and modifications of classifications from the descriptive, reconstructive and prosthodontic perspectives. No globally acceptable classification exists among practitioners involved in the management of diseases in the mid-facial region. There were over 14 classifications of maxillary defects found in the English literature. Attempts made to address the inadequacies of previous classifications have tended to result in cumbersome and relatively complex classifications. A single classification that is based on both surgical and prosthetic considerations is most desirable and is hereby proposed.

Electroreduction of CO ₂ Catalyzed by a Heterogenized Zn–Porphyrin Complex with a Redox-Innocent Metal Center

Energy Technology Data Exchange (ETDEWEB)

Wu, Yueshen [Department; Energy; Jiang, Jianbing [Department; Energy; Weng, Zhe [Department; Energy; Wang, Maoyu [School; Broere, Daniël L. J. [Department; Zhong, Yiren [Department; Energy; Brudvig, Gary W. [Department; Energy; Feng, Zhenxing [School; Wang, Hailiang [Department; Energy

2017-07-26

Transition-metal-based molecular complexes are a class of catalyst materials for electrochemical CO2 reduction to CO that can be rationally designed to deliver high catalytic performance. One common mechanistic feature of these electrocatalysts developed thus far is an electrogenerated reduced metal center associated with catalytic CO2 reduction. Here we report a heterogenized zinc–porphyrin complex (zinc(II) 5,10,15,20-tetramesitylporphyrin) as an electrocatalyst that delivers a turnover frequency as high as 14.4 site–1 s–1 and a Faradaic efficiency as high as 95% for CO2 electroreduction to CO at -1.7 V vs the standard hydrogen electrode in an organic/water mixed electrolyte. While the Zn center is critical to the observed catalysis, in situ and operando X-ray absorption spectroscopic studies reveal that it is redox-innocent throughout the potential range. Cyclic voltammetry indicates that the porphyrin ligand may act as a redox mediator. Chemical reduction of the zinc–porphyrin complex further confirms that the reduction is ligand-based and the reduced species can react with CO2. This represents the first example of a transition-metal complex for CO2 electroreduction catalysis with its metal center being redox-innocent under working conditions.

Identification of nickel-vacancy defects by combining experimental and ab initio simulated photocurrent spectra

Science.gov (United States)

Londero, E.; Bourgeois, E.; Nesladek, M.; Gali, A.

2018-06-01

There is a continuous search for solid state spin qubits operating at room temperature with excitation in the infrared communication bandwidth. Recently, we have introduced the photoelectric detection of magnetic resonance (PDMR) to read the electron spin state of nitrogen-vacancy (NV) centers in diamond, a technique which is promising for applications in quantum information technology. By measuring the photoionization spectra on a diamond crystal, we found two ionization thresholds of unknown origin. On the same sample we also observed absorption and photoluminescence signatures that were identified in the literature as Ni-associated defects. We performed ab initio calculations of the photoionization cross section of the nickel split-vacancy complex (NiV) and N-related defects in their relevant charge states and fitted the concentration of these defects to the measured photocurrent spectrum, which led to a surprising match between experimental and calculated spectra. This study enabled us to identify the two unknown ionization thresholds with the two acceptor levels of NiV. Because the excitation of NiV is in the infrared, the photocurrent detected from the paramagnetic NiV color centers is a promising way towards the design of electrically readout qubits.

Robotic Transversus Abdominis Release (TAR: is it possible to offer minimally invasive surgery for abdominal wall complex defects?

Directory of Open Access Journals (Sweden)

MARIA VITÓRIA FRANÇA DO AMARAL

Full Text Available ABSTRACT We describe the preliminary national experience and the early results of the use of robotic surgery to perform the posterior separation of abdominal wall components by the Transversus Abdominis Release (TAR technique for the correction of complex defects of the abdominal wall. We performed the procedures between 04/2/2015 and 06/15/2015 and the follow-up time was up to six months, with a minimum of two months. The mean surgical time was five hours and 40 minutes. Two patients required laparoscopic re-intervention, since one developed hernia by peritoneal migration of the mesh and one had mesh extrusion. The procedure proved to be technically feasible, with a still long surgical time. Considering the potential advantages of robotic surgery and those related to TAR and the results obtained when these two techniques are associated, we conclude that they seem to be a good option for the correction of complex abdominal wall defects.

Atrial septal defect in a Korean wild raccoon dog.

Science.gov (United States)

Yim, Soomi; Choi, Sooyoung; Kim, Jongtaek; Chung, Jin-Young; Park, Inchul

2017-10-07

An approximately two-year-old, male 6.1 kg body weight, Korean wild raccoon dog (Nyctereutes procyonoides koreensis) was captured by the wildlife medical rescue center of Kangwon National University. Upon physical examination, the heart rate was 87 beats per min and there were no clinical signs. The hematological, and blood biochemical profiles revealed no remarkable findings; however, thoracic radiographs showed cardiac enlargement, especially in the right atrium. On electrocardiogram, sinus node dysfunction and bradyarrhythmia were revealed. Echocardiography showed a left-to-right shunting atrial septal defect. Based on these findings, this Korean wild raccoon dog was diagnosed with atrial septal defect. This is the rare case report of atrial septal defect in wildlife.

The role of point defects and defect complexes in silicon device processing. Summary report and papers

Energy Technology Data Exchange (ETDEWEB)

Sopori, B.; Tan, T.Y.

1994-08-01

This report is a summary of a workshop hold on August 24--26, 1992. Session 1 of the conference discussed characteristics of various commercial photovoltaic silicon substrates, the nature of impurities and defects in them, and how they are related to the material growth. Session 2 on point defects reviewed the capabilities of theoretical approaches to determine equilibrium structure of defects in the silicon lattice arising from transitional metal impurities and hydrogen. Session 3 was devoted to a discussion of the surface photovoltaic method for characterizing bulk wafer lifetimes, and to detailed studies on the effectiveness of various gettering operations on reducing the deleterious effects of transition metals. Papers presented at the conference are also included in this summary report.

Electron paramagnetic resonance study on the ionizing radiation induced defects of the tooth enamel hydroxyapatite

International Nuclear Information System (INIS)

Oliveira, Liana Macedo de

1995-01-01

Hydroxyapatite is the main constituent of calcified tissues. Defects induced by ionizing radiations in this biomineral can present high stability and then, these are used as biological markers in radiological accidents, irradiated food identifying and geological and archaeological dating. In this work, paramagnetic centers induced on the enamel of the teeth by environmental ionizing radiation, are investigated by electron paramagnetic resonance (EPR). Decay thermal kinetic presents high complexity and shows the formation of different electron ligation energy centers and structures

Electronic and atomic structure of complex defects in Al- and Ga-highly doped ZnO films

Energy Technology Data Exchange (ETDEWEB)

Menéndez-Proupin, Eduardo [Instituto de Energía Solar, Universidad Politécnica de Madrid (UPM), Ciudad Universitaria, 28040 Madrid (Spain); Departamento de Física, Facultad de Ciencias, Universidad de Chile, Las Palmeras 3425, 780-0003 Ñuñoa, Santiago (Chile); Palacios, Pablo, E-mail: pablo.palacios@upm.es [Instituto de Energía Solar, Universidad Politécnica de Madrid (UPM), Ciudad Universitaria, 28040 Madrid (Spain); Dpt. FAIAN, E.T.S.I. Aeronáutica y del Espacio, UPM, Pz. Cardenal Cisneros 3, 28040 Madrid (Spain); Wahnón, Perla [Instituto de Energía Solar, Universidad Politécnica de Madrid (UPM), Ciudad Universitaria, 28040 Madrid (Spain); Dpt. TFO, E.T.S.I. Telecomunicación, UPM, Ciudad Universitaria, 28040 Madrid (Spain)

2015-06-15

Point defects in Ga- and Al-doped ZnO thin films are studied by means of first principles electronic structure calculations. Candidate defects are identified to explain recently observed differences in electrical and spectroscopic behavior of both systems. Substitutional doping in Ga–ZnO explain the metallic behavior of the electrical properties. Complexes of interstitial oxygen with substitutional Ga can behave as acceptor and cause partial compensation, as well as gap states below the conduction band minimum as observed in photoemission experiments. Zn vacancies can also act as compensating acceptors. On the other hand, the semiconducting behavior of Al–ZnO and the small variation in the optical gap compared with pure ZnO, can be explained by almost complete compensation between acceptor Zn vacancies and substitutional Al donors. Interstitial Al can also be donor levels and can be the origin of the small band observed in photoemission experiments below the Fermi level. Combinations of substitutional Al with interstitial oxygen can act simultaneously as compensating acceptor and generator of the mentioned photoemission band. The theoretical calculations have been done using density functional theory (DFT) within the generalized gradient approximation with on-site Coulomb interaction. In selected cases, DFT calculations with semilocal-exact exchange hybrid functionals have been performed. Results explain photoelectron spectra of Ga–ZnO and Al–ZnO at the corresponding doping levels. - Highlights: • Defects in Ga- and Al-heavy-doped ZnO films are studied by quantum calculations. • Defects compatible with electrical, optical, and HAXPES spectra are proposed. • Doping efficiency is reduced by Zn vacancies and O interstitials. • HAXPES bands near the Fermi level are induced by Al{sub i}, and complexes Ga{sub Zn}-O{sub i}, and Al{sub Zn}-O{sub i}.

Ebstein's anomaly in children: a single-center study in Angola.

Science.gov (United States)

Manuel, Valdano; Morais, Humberto; Magalhães, Manuel Pedro; Nunes, Maria Ana Sampaio; Leon, Gilberto; Ferreira, Manuel; Filipe Júnior, António Pedro

2015-10-01

Ebstein's anomaly is a rare complex congenital heart defect of the tricuspid valve. We aimed to describe the frequency, clinical profile, and early and short-term post-operative results in patients under the age of 18 years operated for this anomaly in a tertiary center in Angola. A retrospective cross-sectional study was conducted over a period of 37 months. We analyzed all patients diagnosed with congenital heart defects. Of the 1362 patients studied, eight (0.6%) had Ebstein's anomaly; six patients (75%) were female. Mean age was 69±59 months. Five patients were in NYHA functional class III or IV. Mean cardiothoracic index was 0.72. Seven patients (87.5%) had severe tricuspid regurgitation and five (62.5%) had another associated congenital heart defect. All patients were operated: two had complications and one (12.5%) died in the early post-operative period. The mean follow-up time was 1.22±0.6 years, and mortality during follow-up was 12.5% (n=1). At the end of the study, of the five patients in whom cone reconstruction was performed, four (80%) were in functional class I. Mean cardiothoracic index decreased to 0.64. Three patients had mild and two had moderate tricuspid regurgitation. The patient who underwent cone reconstruction and a Glenn procedure was in functional class I. The frequency of Ebstein's anomaly was similar to that in other centers. Cone reconstruction was viable in the majority of patients, with good early and short-term results. Copyright © 2015 Sociedade Portuguesa de Cardiologia. Published by Elsevier España. All rights reserved.

Direct comparison of photoluminescence lifetime and defect densities in ZnO epilayers studied by time-resolved photoluminescence and slow positron annihilation techniques

Energy Technology Data Exchange (ETDEWEB)

Koida, T. [Institute of Applied Physics and Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8573 (Japan); NICP, ERATO, Japan Science and Technology Agency (JST), Chiyoda 102-0071 (Japan); Uedono, A. [Institute of Applied Physics and Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8573 (Japan); Tsukazaki, A. [Institute for Materials Research, Tohoku University, Sendai 980-8755 (Japan); Sota, T. [Department of Electrical, Engineering and Bioscience, Waseda University, Shinjuku 169-8555 (Japan); Kawasaki, M. [Institute for Materials Research, Tohoku University, Sendai 980-8755 (Japan); Combinatorial Materials Exploration and Technology (COMET), Tsukuba 305-0044 (Japan); Chichibu, S.F. [NICP, ERATO, Japan Science and Technology Agency (JST), Chiyoda 102-0071 (Japan); Photodynamics Research Center, RIKEN, Sendai 980-0868 (Japan)

2004-09-01

The roles of point defects and defect complexes governing nonradiative processes in ZnO epilayers were studied using time-resolved photoluminescence (PL) and slow positron annihilation measurements. The density or size of Zn vacancies (V{sub Zn}) decreased and the nonradiative PL lifetime ({tau}{sub nr}) increased with higher growth temperature for epilayers grown on a ScAlMgO{sub 4} substrate. Accordingly, the steady-state free excitonic PL intensity increased with increase in {tau}{sub nr} at room temperature. The use of a homoepitaxial substrate further decreased the V{sub Zn} concentration. However, no perfect relation between {tau}{sub nr} and the density or size of V{sub Zn} or other positron scattering centers was found. The results indicated that nonradiative recombination processes are governed not solely by single point defects, but by certain defect species introduced by the presence of V{sub Zn} such as vacancy complexes. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Defect mediated optical properties in ZnAl2O4 phosphor

Science.gov (United States)

Pathak, Nimai; Saxena, Suryansh; Kadam, R. M.

2018-04-01

The present work describes defect mediated optical properties in ZnAl2O4 phosphor material, synthesized through sol-gel combustion method, which has potential to be used both as a blue emitting phosphor material as well as white emitting, depending upon the annealing temperature during the synthesis procedure. Various defect centers such as anionic vacancy, cationic vacancy, antisite defects etc. create different electronic states inside the band gap, which are responsible for the multicolour emission. The interesting colour tunable emission characteristics can be linked with the various defect centers and their changes upon annealing.

A-centers in silicon studied with hybrid density functional theory

KAUST Repository

Wang, Hao; Chroneos, Alexander; Londos, C. A.; Schwingenschlö gl, Udo; Sgourou, E. N.

2013-01-01

Density functional theory employing hybrid functional is used to gain fundamental insight into the interaction of vacancies with oxygen interstitials to form defects known as A-centers in silicon. We calculate the formation energy of the defect with respect to the Fermi energy for all possible charge states. It is found that the neutral and doubly negatively charged A-centers dominate. The findings are analyzed in terms of the density of states and discussed in view of previous experimental and theoretical studies.

A-centers in silicon studied with hybrid density functional theory

KAUST Repository

Wang, Hao

2013-07-29

Density functional theory employing hybrid functional is used to gain fundamental insight into the interaction of vacancies with oxygen interstitials to form defects known as A-centers in silicon. We calculate the formation energy of the defect with respect to the Fermi energy for all possible charge states. It is found that the neutral and doubly negatively charged A-centers dominate. The findings are analyzed in terms of the density of states and discussed in view of previous experimental and theoretical studies.

Ionization-induced rearrangement of defects in silicon

International Nuclear Information System (INIS)

Vinetskij, V.L.; Manojlo, M.A.; Matvijchuk, A.S.; Strikha, V.I.; Kholodar', G.A.

1988-01-01

Ionizing factor effect on defect rearrangement in silicon including centers with deep local electron levels in the p-n-transition region is considered. Deep center parameters were determined using non-steady-state capacity spectroscopy of deep levels (NCDLS) method. NCDLS spectrum measurement was performed using source p + -n - diodes and after their irradiation with 15 keV energy electrons or laser pulses. It is ascertained that in silicon samples containing point defect clusters defect rearrangement under ionizing factor effect takes place, i.e. deep level spectra are changed. This mechanism is efficient in case of silicon irradiation with subthreshold energy photons and electrons and can cause degradation of silicon semiconducting structures

Cor triatriatum dexter associated with atrial septal defect: Management in a complex clinical case.

Science.gov (United States)

Sozzi, Fabiola B; Montanaro, Claudia; Bacà, Laura; Viani, Giacomo M; Zilocchi, Massimo; Canetta, Ciro; Meazza, Roberto; Pavone, Laura; Lombardi, Federico

2017-11-01

The coexistence of an atrial septal defect and a prominent eustachian valve is a rare congenital anomaly, rarely reported in literature. Differentiation between a giant eustachian valve and cor triatriatum dexter can be difficult. A case of a large atrial septal defect associated with cor triatriatum dexter diagnosed by echocardiography in an asymptomatic woman is reported. A watchful waiting strategy was adopted. © 2017, Wiley Periodicals, Inc.

Identification of vacancy defect complexes in transparent semiconducting oxides ZnO, In2O3 and SnO2

International Nuclear Information System (INIS)

Makkonen, Ilja; Korhonen, Esa; Prozheeva, Vera; Tuomisto, Filip

2016-01-01

Positron annihilation spectroscopy, when combined with supporting high-quality modeling of positron states and annihilation in matter, is a powerful tool for detailed defect identification of vacancy-type defects in semiconductors and oxides. Here we demonstrate that the Doppler broadening of the positron annihilation radiation is a very sensitive means for observing the oxygen environment around cation vacancies, the main open-volume defects trapping positrons in measurements made for transparent semiconducting oxides. Changes in the positron annihilation signal due to external manipulation such as irradiation and annealing can be correlated with the associated changes in the sizes of the detected vacancy clusters. Our examples for ZnO, In 2 O 3 and SnO 2 demonstrate that oxygen vacancies in oxides can be detected directly using positron annihilation spectroscopy when they are complexed with cation vacancies. (paper)

Identification of vacancy defect complexes in transparent semiconducting oxides ZnO, In2O3 and SnO2

Science.gov (United States)

Makkonen, Ilja; Korhonen, Esa; Prozheeva, Vera; Tuomisto, Filip

2016-06-01

Positron annihilation spectroscopy, when combined with supporting high-quality modeling of positron states and annihilation in matter, is a powerful tool for detailed defect identification of vacancy-type defects in semiconductors and oxides. Here we demonstrate that the Doppler broadening of the positron annihilation radiation is a very sensitive means for observing the oxygen environment around cation vacancies, the main open-volume defects trapping positrons in measurements made for transparent semiconducting oxides. Changes in the positron annihilation signal due to external manipulation such as irradiation and annealing can be correlated with the associated changes in the sizes of the detected vacancy clusters. Our examples for ZnO, In2O3 and SnO2 demonstrate that oxygen vacancies in oxides can be detected directly using positron annihilation spectroscopy when they are complexed with cation vacancies.

Defect creation in solids by a decay of electronic excitations

International Nuclear Information System (INIS)

Klinger, M.I.; Lushchik, Ch.B.; Mashovets, T.V.; Kholodar', G.A.; Shejnkman, M.K.; Ehlango, M.A.; Kievskij Gosudarstvennyj Univ.; AN Ukrainskoj SSR, Kiev. Inst. Poluprovodnikov)

1985-01-01

A new type of radiationless transitions in nonmetallic solids accompanied by neither the extraction of a heat nor the luminescence, but by a large (in comparison with the interatomic distance) displacements of a small number of atoms is discussed. A classification is given of the instabilities (electrostatic, electron-vibrational, structural) leading to a creation of the defects in crystalline and glassy solids. The processes of the defect creation, due to both the decay of self-trapped excitions in ionic crystals and the multiple ionization of atoms near the pre-existing charged centres in semiconductor are described. The mechanisms of the complex defects reconstruction in semiconductors by nonequilibrium charge carriers and by an electron-hole recombination are discussed. The role of charge carriers in a thermal defect generation is considered. A mechanism of the peculiar defect creation in glassy semiconductors is discussed

Extrinsic- and intrinsic-defect creation in amorphous SiO2

International Nuclear Information System (INIS)

Devine, R.A.B.; Francou, J.

1990-01-01

We have studied the creation efficiency of various intrinsic and extrinsic defects in high-[OH] amorphous silica subjected to the ultraviolet emission from an O 2 plasma or 60 Co γ-ray radiation. Both oxygen-vacancy- and nitrogen-related defects are observed following γ-ray irradiation or ultraviolet exposure. The wavelength range responsible for defect creation is estimated to be 200 approx-lt λ approx-lt 300 nm (4 approx-lt E photon approx-lt 5.9 eV). The ultraviolet power output of the plasma estimated by comparing defect yields with those from a Hg lamp (λ=185 and 254 nm) suggests 200 approx-lt P approx-lt 900 mW cm -2 for a plasma power density ∼300 mW cm -3 . Nonbridging oxygen-hole centers and hydrogen-related defect centers as well as methyl radical (CH 3 . ) defects are observed after γ-ray irradiation but not after ultraviolet exposure. The efficiency of creation of the various defects is material dependent

Quantum interference between two phonon paths and reduced heat transport in diamond lattice with atomic-scale planar defects

Science.gov (United States)

Kosevich, Yu. A.; Strelnikov, I. A.

2018-02-01

Destructive quantum interference between the waves propagating through laterally inhomogeneous layer can result in their total reflection, which in turn reduces energy flux carried by these waves. We consider the systems of Ge atoms, which fully or partly, in the chequer-wise order, fill a crystal plane in diamond-like Si lattice. We have revealed that a single type of the atomic defects, which are placed in identical positions in different unit cells in the defect crystal plane, can result in double transmission antiresonances of phonon wave packets. This new effect we relate with the complex structure of the diamond-like unit cell, which comprises two atoms in different positions and results in two distinct vibration resonances in two interfering phonon paths. We also consider the propagation of phonon wave packets in the superlatticies made of the defect planes, half-filled in the chequer-wise order with Ge atoms. We have revealed relatively broad phonon stop bands with center frequencies at the transmission antiresonances. We elaborate the equivalent analytical quasi-1D lattice model of the two phonon paths through the complex planar defect in the diamond-like lattice and describe the reduction of phonon heat transfer through the atomic-scale planar defects.

Point-Defect Nature of the Ultraviolet Absorption Band in AlN

Science.gov (United States)

Alden, D.; Harris, J. S.; Bryan, Z.; Baker, J. N.; Reddy, P.; Mita, S.; Callsen, G.; Hoffmann, A.; Irving, D. L.; Collazo, R.; Sitar, Z.

2018-05-01

We present an approach where point defects and defect complexes are identified using power-dependent photoluminescence excitation spectroscopy, impurity data from SIMS, and density-functional-theory (DFT)-based calculations accounting for the total charge balance in the crystal. Employing the capabilities of such an experimental computational approach, in this work, the ultraviolet-C absorption band at 4.7 eV, as well as the 2.7- and 3.9-eV luminescence bands in AlN single crystals grown via physical vapor transport (PVT) are studied in detail. Photoluminescence excitation spectroscopy measurements demonstrate the relationship between the defect luminescent bands centered at 3.9 and 2.7 eV to the commonly observed absorption band centered at 4.7 eV. Accordingly, the thermodynamic transition energy for the absorption band at 4.7 eV and the luminescence band at 3.9 eV is estimated at 4.2 eV, in agreement with the thermodynamic transition energy for the CN- point defect. Finally, the 2.7-eV PL band is the result of a donor-acceptor pair transition between the VN and CN point defects since nitrogen vacancies are predicted to be present in the crystal in concentrations similar to carbon-employing charge-balance-constrained DFT calculations. Power-dependent photoluminescence measurements reveal the presence of the deep donor state with a thermodynamic transition energy of 5.0 eV, which we hypothesize to be nitrogen vacancies in agreement with predictions based on theory. The charge state, concentration, and type of impurities in the crystal are calculated considering a fixed amount of impurities and using a DFT-based defect solver, which considers their respective formation energies and the total charge balance in the crystal. The presented results show that nitrogen vacancies are the most likely candidate for the deep donor state involved in the donor-acceptor pair transition with peak emission at 2.7 eV for the conditions relevant to PVT growth.

Metastable and bistable defects in silicon

International Nuclear Information System (INIS)

Mukashev, Bulat N; Abdullin, Kh A; Gorelkinskii, Yurii V

2000-01-01

Existing data on the properties and structure of metastable and bistable defects in silicon are analyzed. Primary radiation-induced defects (vacancies, self-interstitial atoms, and Frenkel pairs), complexes of oxygen, carbon, hydrogen, and other impurity atoms and defects with negative correlation energy are considered. (reviews of topical problems)

Annealing study of the electron-irradiation-induced defects H4 and E11 in InP: Defect transformation (H4-E11)→H4'

International Nuclear Information System (INIS)

Bretagnon, T.; Bastide, G.; Rouzeyre, M.

1990-01-01

Capacitance spectroscopy has been used to study the two dominant deep levels, H 4 and E 11 , produced in InP by low-energy electron irradiation. The annealing rates of H 4 and E 11 in the p-type material are found to be identical, as is also the dependence on free-carrier recombination and on the chemical nature of the acceptor (Cd or Zn). Recombination-enhanced annealing converts these traps to a hole trap H 4 ' , which is not detectable by conventional deep-level transient spectroscopy. Its emission and capture properties are measured and analyzed. The similarity of the creation and annealing behavior of H 4 and E 11 shows that they share a common point defect. Our results lead to the tentative identification of the defect as a phosphorous vacancy-acceptor complex and we show how this may anneal to the H 4 ' center

G-centers in irradiated silicon revisited: A screened hybrid density functional theory approach

KAUST Repository

Wang, H.

2014-05-13

Electronic structure calculations employing screened hybrid density functional theory are used to gain fundamental insight into the interaction of carbon interstitial (Ci) and substitutional (Cs) atoms forming the CiCs defect known as G-center in silicon (Si). The G-center is one of the most important radiation related defects in Czochralski grown Si. We systematically investigate the density of states and formation energy for different types of CiCs defects with respect to the Fermi energy for all possible charge states. Prevalence of the neutral state for the C-type defect is established.

Electronic structure properties of deep defects in hBN

Science.gov (United States)

Dev, Pratibha; Prdm Collaboration

In recent years, the search for room-temperature solid-state qubit (quantum bit) candidates has revived interest in the study of deep-defect centers in semiconductors. The charged NV-center in diamond is the best known amongst these defects. However, as a host material, diamond poses several challenges and so, increasingly, there is an interest in exploring deep defects in alternative semiconductors such as hBN. The layered structure of hBN makes it a scalable platform for quantum applications, as there is a greater potential for controlling the location of the deep defect in the 2D-matrix through careful experiments. Using density functional theory-based methods, we have studied the electronic and structural properties of several deep defects in hBN. Native defects within hBN layers are shown to have high spin ground states that should survive even at room temperature, making them interesting solid-state qubit candidates in a 2D matrix. Partnership for Reduced Dimensional Material (PRDM) is part of the NSF sponsored Partnerships for Research and Education in Materials (PREM).

Short-term outcomes of transcatheter closure of secundum atrial septal defect in children and adolescents: An experience of two centers in Upper Egypt

Directory of Open Access Journals (Sweden)

Safaa H. Ali

2018-01-01

Conclusions: Transcatheter closure of ASDs in children and adolescents was feasible and safe in the first 4 years experience in our centers, with good short-term outcome. Balloon sizing is not necessary for transcatheter closure of secundum ASD. Multiple defects can be safety closed by a single device.

Amelia: A Multi-Center Descriptive Epidemiologic Study in a Large Dataset from the International Clearinghouse for Birth Defects Surveillance and Research, and Overview of the Literature

Science.gov (United States)

BERMEJO-SÁNCHEZ, EVA; CUEVAS, LOURDES; AMAR, EMMANUELLE; BAKKER, MARIAN K.; BIANCA, SEBASTIANO; BIANCHI, FABRIZIO; CANFIELD, MARK A.; CASTILLA, EDUARDO E.; CLEMENTI, MAURIZIO; COCCHI, GUIDO; FELDKAMP, MARCIA L.; LANDAU, DANIELLE; LEONCINI, EMANUELE; LI, ZHU; LOWRY, R. BRIAN; MASTROIACOVO, PIERPAOLO; MUTCHINICK, OSVALDO M.; RISSMANN, ANKE; RITVANEN, ANNUKKA; SCARANO, GIOACCHINO; SIFFEL, CSABA; SZABOVA, ELENA; MARTÍNEZ-FRÍAS, MARÍA-LUISA

2015-01-01

This study describes the epidemiology of congenital amelia (absence of limb/s), using the largest series of cases known to date. Data were gathered by 20 surveillance programs on congenital anomalies, all International Clearinghouse for Birth Defects Surveillance and Research members, from all continents but Africa, from 1968 to 2006, depending on the program. Reported clinical information on cases was thoroughly reviewed to identify those strictly meeting the definition of amelia. Those with amniotic bands or limb-body wall complex were excluded. The primary epidemiological analyses focused on isolated cases and those with multiple congenital anomalies (MCA). A total of 326 amelia cases were ascertained among 23,110,591 live births, stillbirths and (for some programs) elective terminations of pregnancy for fetal anomalies. The overall total prevalence was 1.41 per 100,000 (95% confidence interval: 1.26–1.57). Only China Beijing and Mexico RYVEMCE had total prevalences, which were significantly higher than this overall total prevalence. Some under-registration could influence the total prevalence in some programs. Liveborn cases represented 54.6% of total. Among monomelic cases (representing 65.2% of nonsyndromic amelia cases), both sides were equally involved, and the upper limbs (53.9%) were slightly more frequently affected. One of the most interesting findings was a higher prevalence of amelia among offspring of mothers younger than 20 years. Sixty-nine percent of the cases had MCA or syndromes. The most frequent defects associated with amelia were other types of musculoskeletal defects, intestinal, some renal and genital defects, oral clefts, defects of cardiac septa, and anencephaly. PMID:22002956

Experimental evidence for an associated defect model for the neutron generated As/sub Ga/ center in gallium arsenide

International Nuclear Information System (INIS)

Golzene, A.; Meyer, B.; Schwab, C.

1984-01-01

The thermal dependence of EPR spectra of fast neutron irradiated n-type GaAs over the whole 4.2 to 300 K temperature range has been studied using the decomposition of spectra into a quadruplet of four identical Gaussian lines and a Lorentzian singlet. Quadruplet and singlet spectra as well as their proper parameters (inverse of paramagnetic susceptibility, hyperfine constants) could be determined separately. Experiments give evidence that the neutron generated anionic antisites As/sub Ga/ in GaAs are constituting associated defect centers, most likely of intrinsic nature

THE RESULTS OF THE DEFECT PLACES INVESTIGATION OF DONETSK RAILWAY ROAD BED BY GROUND PENETRATING RADAR COMPLEX

Directory of Open Access Journals (Sweden)

V. D. Petrenko

2014-10-01

Full Text Available Purpose. Defective places definition of road bed at ground penetrating radar is examined. Methodology. For achievement of this goal the experimental research on ground penetrating radar inspection of road bed defective places of the Donetsk Railway, which are caused by a complex of various reasons of geotechnical and constructive character, were conducted. Findings. According to these diagnostic results of road bed on the three districts of the Donetsk Railway is revealed the main causes which lead to the defects appearance, deformities and injuries in it, there is abuse of process parameters and modify its physic mechanical soil properties of natural and technology-related factors. As it is established, the use of ground penetrating radar of series “Losa” on the railways of Ukraine allows searching ballast tank in the body of road bed, defining damp places in soil road bed and foundations, to find arrangement of foreign matter in the soil road bed and work search heterogeneity and places weakening soil. In addition, the use of ground penetrating radar provides rapid detection of defects, deformation and damage of railway track, especially in areas the most dangerous for rolling stock that creates the high level security at the main and auxiliary lines of Ukrzaliznytsia. In conducting the research was justified the high level of reliability and performance with autonomous use of ground penetrating radar. Originality. In modern conditions of defects determination, deformations and damages by traditional methods with application of engineering-geological investigations, it is impossible in connection with their insufficient efficiency. Therefore the using of highly effective methodology of expeditious tool identification of defective places allows reducing significantly the periods of repair of a railway track which is very important for introduction of the high-speed movement on the Ukrainian Railways. Practical value. On the basis of the

Positron annihilation lifetime in float-zone n-type silicon irradiated by fast electrons: a thermally stable vacancy defect

International Nuclear Information System (INIS)

Arutyunov, Nikolay; Emtsev, Vadim; Oganesyan, Gagik; Krause-Rehberg, Reinhard; Elsayed, Mohamed; Kozlovskii, Vitalii

2016-01-01

Temperature dependency of the average positron lifetime has been investigated for n-type float-zone silicon, n-FZ-Si(P), subjected to irradiation with 0.9 MeV electrons at RT. In the course of the isochronal annealing a new defect-related temperature-dependent pattern of the positron lifetime spectra has been revealed. Beyond the well known intervals of isochronal annealing of acceptor-like defects such as E-centers, divacancies and A-centers, the positron annihilation at the vacancy defects has been observed in the course of the isochronal annealing from ∝ 320 C up to the limit of reliable detecting of the defect-related positron annihilation lifetime at ≥ 500 C. These data correlate with the ones of recovery of the concentration of the charge carriers and their mobility which is found to continue in the course of annealing to ∝ 570 C; the annealing is accomplished at ∝650 C. A thermally stable complex consisting of the open vacancy volume and the phosphorus impurity atom, V_o_p-P, is suggested as a possible candidate for interpreting the data obtained by the positron annihilation lifetime spectroscopy. An extended couple of semi-vacancies, 2V_s_-_e_x_t, as well as a relaxed inwards a couple of vacancies, 2V_i_n_w, are suggested as the open vacancy volume V_o_p to be probed with the positron. It is argued that a high thermal stability of the V_s_-_e_x_t PV_s_-_e_x_t (or V_i_n_wPV_i_n_w_.) configuration is contributed by the efficiency of PSi_5 bonding. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Radiation-induced defect production in MgF2-Co crystals

International Nuclear Information System (INIS)

Nuritdinov, I.; Turdanov, K.; Mirinoyatova, N.M.; Rejterov, V.M.

1996-01-01

Impact of Co-admixture on structural radiation defects formation in the MgF 2 crystals is studied. It is found that the Co admixture facilitates the probability of generating the F- and m-type centers of radiation defects as well as creation of the F- and M-centers, perturbed by admixtures. The availability of structural defects leads in its turn to the admixture ions perturbation. It is reflected in the removal of prohibition on spin-prohibited transitions of the Co 2 + ions. It is assumed that creation of the M-centers is the main cause for removal of the prohibition on the spin-prohibited transitions. 8 refs., 4 figs

Defective FANCI binding by a fanconi anemia-related FANCD2 mutant.

Directory of Open Access Journals (Sweden)

Koichi Sato

Full Text Available FANCD2 is a product of one of the genes associated with Fanconi anemia (FA, a rare recessive disease characterized by bone marrow failure, skeletal malformations, developmental defects, and cancer predisposition. FANCD2 forms a complex with FANCI (ID complex and is monoubiquitinated, which facilitates the downstream interstrand crosslink (ICL repair steps, such as ICL unhooking and nucleolytic end resection. In the present study, we focused on the chicken FANCD2 (cFANCD2 mutant harboring the Leu234 to Arg (L234R substitution. cFANCD2 L234R corresponds to the human FANCD2 L231R mutation identified in an FA patient. We found that cFANCD2 L234R did not complement the defective ICL repair in FANCD2-/- DT40 cells. Purified cFANCD2 L234R did not bind to chicken FANCI, and its monoubiquitination was significantly deficient, probably due to the abnormal ID complex formation. In addition, the histone chaperone activity of cFANCD2 L234R was also defective. These findings may explain some aspects of Fanconi anemia pathogenesis by a FANCD2 missense mutation.

Effect of interaction between irradiation-induced defects and intrinsic defects in the pinning improvement of neutron irradiated YBaCuO sample

International Nuclear Information System (INIS)

Topal, Ugur; Sozeri, Huseyin; Yavuz, Hasbi

2004-01-01

Interaction between the intrinsic (native) defects and the irradiation-induced defects created by neutron irradiation was examined for the YBCO sample. For this purpose, non-superconducting Y-211 phase was included to the Y-123 samples at different contents as a source of large pinning center. The critical current density enhancement with the irradiation for these samples were analysed and then the role of defects on pinning improvement was discussed

Effect of interaction between irradiation-induced defects and intrinsic defects in the pinning improvement of neutron irradiated YBaCuO sample

Energy Technology Data Exchange (ETDEWEB)

Topal, Ugur; Sozeri, Huseyin; Yavuz, Hasbi

2004-08-01

Interaction between the intrinsic (native) defects and the irradiation-induced defects created by neutron irradiation was examined for the YBCO sample. For this purpose, non-superconducting Y-211 phase was included to the Y-123 samples at different contents as a source of large pinning center. The critical current density enhancement with the irradiation for these samples were analysed and then the role of defects on pinning improvement was discussed.

Electrical characterization of defects introduced in n-Si during electron beam deposition of Pt

Energy Technology Data Exchange (ETDEWEB)

Auret, F.D.; Coelho, S.M.M.; Nel, J.M.; Meyer, W.E. [Physics Department, University of Pretoria, Pretoria (South Africa)

2012-10-15

We have used deep level transient spectroscopy (DLTS) and high resolution DLTS to characterize the defects introduced in epitaxially grown n-type, P-doped, Si during electron beam deposition (EBD) of Pt for Schottky contact formation. The identity of some of these defects could be established by comparing their properties to those of well-known defects introduced by high energy electron irradiation of the same material. The most prominent EBD-induced defects thus identified were the E-center (VP center), the A-center (VO center), interstitial carbon (C{sub i}), and the interstitial carbon-substitutional carbon (C{sub i}C{sub s}) pair. EBD also introduced some defects that were not observed after high energy electron irradiation. DLTS depth profiling revealed that the main defects, VO and VP, could be detected up to 0.5 {mu}m below the metal-Si interface. Shielding the sample from particles originating in the region of the electron beam significantly reduced defect introduction and resulted in Schottky contacts with improved rectification properties. Finally, we have found that exposing the sample to EBD conditions, without actually depositing metal, introduced a different set of electron traps, not introduced by the EBD process. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Information Center Complex publications and presentations, 1971-1980

International Nuclear Information System (INIS)

Gill, A.B.; Hawthorne, S.W.

1981-08-01

This indexed bibliography lists publications and presentations of the Information Center Complex, Information Division, Oak Ridge National Laboratory, from 1971 through 1980. The 659 entries cover such topics as toxicology, air and water pollution, management and transportation of hazardous wastes, energy resources and conservation, and information science. Publications range in length from 1 page to 3502 pages and include topical reports, books, journal articles, fact sheets, and newsletters. Author, title, and group indexes are provided. Annual updates are planned

Information Center Complex publications and presentations, 1971-1980

Energy Technology Data Exchange (ETDEWEB)

Gill, A.B.; Hawthorne, S.W.

1981-08-01

This indexed bibliography lists publications and presentations of the Information Center Complex, Information Division, Oak Ridge National Laboratory, from 1971 through 1980. The 659 entries cover such topics as toxicology, air and water pollution, management and transportation of hazardous wastes, energy resources and conservation, and information science. Publications range in length from 1 page to 3502 pages and include topical reports, books, journal articles, fact sheets, and newsletters. Author, title, and group indexes are provided. Annual updates are planned.

Study of irradiation induced defects in silicon

International Nuclear Information System (INIS)

Pal, Gayatri; Sebastian, K.C.; Somayajulu, D.R.S.; Chintalapudi, S.N.

2000-01-01

Pure high resistivity (6000 ohm-cm) silicon wafers were recoil implanted with 1.8 MeV 111 In ions. As-irradiated wafers showed a 13 MHz quadrupole interaction frequency, which was not observed earlier. The annealing behaviour of these defects in the implanted wafers was studied between room temperature and 1073 K. At different annealing temperatures two more interaction frequencies corresponding to defect complexes D2 and D3 are observed. Even though the experimental conditions were different, these are identical to the earlier reported ones. Based on an empirical point charge model calculation, an attempt is made to identify the configuration of these defect complexes. (author)

Temperature dependence of radiation induced defect creation in a-SiO2

International Nuclear Information System (INIS)

Devine, R.A.B.; Grouillet, A.; Berlivet, J.Y.

1988-01-01

The efficiency of oxygen vacancy defect creation in samples of amorphous SiO 2 subjected to ultraviolet laser or ionizing particle radiation (energetic H + ions) has been measured as a function of sample temperature during irradiation. For the case of laser radiation (E photon ≅ 5 eV) we find that vacancy centers are only created when the irradiation temperature is above 150 K. The efficiency of peroxy radical defect creation observed after post irradiation annealing is consistent with the behaviour of the oxygen vacancy creation efficiency. In samples with energetic protons, the opposite behaviour is observed and one finds that defect creation is enhanced as the implantation temperature is lowered. Possible physical mechanisms controlling the defect creation efficiency as a function of sample temperature and radiation are discussed. (orig.)

Peculiarities of radiation defect formation and annealing in n-Si due to their interaction with each other and defect clusters

International Nuclear Information System (INIS)

Lugakov, P.F.; Lukyanitsa, V.V.

1984-01-01

Rearrangement processes proceeding during annealing (T/sub a/ = 50 to 500 0 C) of radiation defects in 60 Co γ-irradiated (T/sub irr/ 0 C) n-Si crystals (rho = 100 to 600 Ωcm) grown by the vacuum float-zone technique are studied. The temperature dependences of the Hall coefficient are measured. The results obtained are interpreted taking into account the interaction during annealing of vacancy-type defects (E-centres, divacancies) with each other and interstitial radiation defects (C/sub i/-C/sub s/ complexes, interstitial carbon C/sub i/). Phosphorus-two vacancies complexes, stable to T/sub a/ >= 500 0 C, are shown to be formed as a result of rearrangements and interaction of E-centres between themselves. The character of interaction of vacancy defects with interstitial ones is found to change significantly in the presence of defect clusters in the bulk of the crystal which are formed under heat treatment (T = 800 0 C, two hours) of the samples preliminary irradiated with fast neutrons (flux PHI/sub n/ = 1x10 14 to 1x10 16 cm -2 ). The peculiarities of radiation defects annealing observed in this case are explained taking into account the influence of defect clusters on the migration processes of mobile defects. Nature of radiation defects being formed at various stages of annealing is discussed. (author)

ILT based defect simulation of inspection images accurately predicts mask defect printability on wafer

Science.gov (United States)

Deep, Prakash; Paninjath, Sankaranarayanan; Pereira, Mark; Buck, Peter

2016-05-01

At advanced technology nodes mask complexity has been increased because of large-scale use of resolution enhancement technologies (RET) which includes Optical Proximity Correction (OPC), Inverse Lithography Technology (ILT) and Source Mask Optimization (SMO). The number of defects detected during inspection of such mask increased drastically and differentiation of critical and non-critical defects are more challenging, complex and time consuming. Because of significant defectivity of EUVL masks and non-availability of actinic inspection, it is important and also challenging to predict the criticality of defects for printability on wafer. This is one of the significant barriers for the adoption of EUVL for semiconductor manufacturing. Techniques to decide criticality of defects from images captured using non actinic inspection images is desired till actinic inspection is not available. High resolution inspection of photomask images detects many defects which are used for process and mask qualification. Repairing all defects is not practical and probably not required, however it's imperative to know which defects are severe enough to impact wafer before repair. Additionally, wafer printability check is always desired after repairing a defect. AIMSTM review is the industry standard for this, however doing AIMSTM review for all defects is expensive and very time consuming. Fast, accurate and an economical mechanism is desired which can predict defect printability on wafer accurately and quickly from images captured using high resolution inspection machine. Predicting defect printability from such images is challenging due to the fact that the high resolution images do not correlate with actual mask contours. The challenge is increased due to use of different optical condition during inspection other than actual scanner condition, and defects found in such images do not have correlation with actual impact on wafer. Our automated defect simulation tool predicts

Electron-spin-resonance study of radiation-induced paramagnetic defects in oxides grown on (100) silicon substrates

International Nuclear Information System (INIS)

Kim, Y.Y.; Lenahan, P.M.

1988-01-01

We have used electron-spin resonance to investigate radiation-induced point defects in Si/SiO 2 structures with (100) silicon substrates. We find that the radiation-induced point defects are quite similar to defects generated in Si/SiO 2 structures grown on (111) silicon substrates. In both cases, an oxygen-deficient silicon center, the E' defect, appears to be responsible for trapped positive charge. In both cases trivalent silicon (P/sub b/ centers) defects are primarily responsible for radiation-induced interface states. In earlier electron-spin-resonance studies of unirradiated (100) substrate capacitors two types of P/sub b/ centers were observed; in oxides prepared in three different ways only one of these centers, the P/sub b/ 0 defect, is generated in large numbers by ionizing radiation

Defects in Cu(In,Ga)Se{sub 2} chalcopyrite semiconductors: a comparative study of material properties, defect states, and photovoltaic performance

Energy Technology Data Exchange (ETDEWEB)

Cao, Qing; Gunawan, Oki; Copel, Matthew; Reuter, Kathleen B; Chey, S Jay; Mitzi, David B [IBM T.J. Watson Research Center, Yorktown Heights, NY (United States); Deline, Vaughn R [IBM Almaden Resesarch Center, San Jose, CA (United States)

2011-10-15

Understanding defects in Cu(In,Ga)(Se,S){sub 2} (CIGS), especially correlating changes in the film formation process with differences in material properties, photovoltaic (PV) device performance, and defect levels extracted from admittance spectroscopy, is a critical but challenging undertaking due to the complex nature of this polycrystalline compound semiconductor. Here we present a systematic comparative study wherein varying defect density levels in CIGS films were intentionally induced by growing CIGS grains using different selenium activity levels. Material characterization results by techniques including X-ray diffraction, scanning electron microscopy, transmission electron microscopy, secondary ion mass spectrometry, X-ray photoelectron spectroscopy, and medium energy ion scattering indicate that this process variation, although not significantly affecting CIGS grain structure, crystal orientation, or bulk composition, leads to enhanced formation of a defective chalcopyrite layer with high density of indium or gallium at copper antisite defects ((In, Ga){sub Cu}) near the CIGS surface, for CIGS films grown with insufficient selenium supply. This defective layer or the film growth conditions associated with it is further linked with observed current-voltage characteristics, including rollover and crossover behavior, and a defect state at around 110 meV (generally denoted as the N1 defect) commonly observed in admittance spectroscopy. The impact of the (In, Ga){sub Cu} defects on device PV performance is also established. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Parameterization of the prosthetic redox centers of the bacterial cytochrome bc(1) complex for atomistic molecular dynamics simulations

DEFF Research Database (Denmark)

Kaszuba, K.; Postila, P. A.; Cramariuc, O.

2013-01-01

studied in large-scale classical molecular dynamics (MD) simulations. In part, this is due to lack of suitable force field parameters, centered atomic point charges in particular, for the complex's prosthetic redox centers. Accurate redox center charges are needed to depict realistically the inter-molecular...... interactions at different redox stages of the cyt bc(1) complex. Accordingly, here we present high-precision atomic point charges for the metal centers of the cyt bc(1) complex of Rhodobacter capsulatus derived from extensive density functional theory calculations, fitted using the restrained electrostatic...

Anomalous defect processes in Si implanted amorphous SiO2, II

International Nuclear Information System (INIS)

Fujita, Tetsuo; Fukui, Minoru; Okada, Syunji; Shimizu-Iwayama, Tsutomu; Hioki, Tatsumi; Itoh, Noriaki

1994-01-01

Aanomalous features of the defects in Si implanted amorphous SiO 2 are reported. The numbers of E 1 prime centers and B 2 centers are found to increase monotonically with implanted Si dose, in contrast to the saturating feature of these numbers in Ar implanted samples. Moreover, when H ions are implanted in amorphous SiO 2 predamaged by Si implantation, both of the density and the number of E 1 prime centers increase and they reach a constant value at a small H dose. We point out that these anomalies can be explained in terms of the difference in the cross-section for defect annihilation in the specimens implanted with Si ions and other ions, in accordance with the homogeneous model proposed by Devine and Golanski. We consider that the main mechanism of defect annihilation is the recombination of an E 1 prime center and an interstitial O, which is stabilized by an implanted Si, reducing the cross-section in Si-implanted specimens. ((orig.))

Formation and relaxation processes of photoinduced defects in a Ge-doped SiO2 glass

International Nuclear Information System (INIS)

Yamaguchi, M.; Saito, K.; Ikushima, A.J.

2002-01-01

The defect centers induced by ArF laser irradiation in Ge-doped SiO 2 have been investigated by the electron-spin resonance method. In order to observe formation and relaxation processes of the defects, step annealing has been carried out after the irradiation at 77 K. The thermally induced decay of the self-trapped hole (STH) and formation of the so-called Ge(2) centers have been observed with increasing temperature. The result suggests that the holes are transferred from the STH to the Ge(2)

A clinical case of single-stage correction of penetration combined orofacial defect with two microsurgical autografts

Directory of Open Access Journals (Sweden)

A. D. Kaprin

2015-01-01

Full Text Available After surgical treatment for locally advanced oral tumors with resection of soft tissues, mucosal membrane, and facial skeletal structures, there are penetration combined defects, removal of which is a challenge for reconstructive surgeons. Mandibular repair is one of the problems in the correction of combined oral defects. Surgeons use different grafts to remove mandibular defects. One-flap transplantation does not always solve all reconstruction problems and ensure the repair of the mucosal membrane, a soft-tissue component, skin integuments, and facial skeleton.The authors describe a clinical case of successful single-stage correction of penetration combined orofacial defect after resection of the tongue, mouth floor, en bloc resection of the lower jaw and mental soft tissues, bilateral cervical supramyochoroidal lymphadenectomy, stage LCL CM mandibular defect formation after J. Boyd, by using two microsurgical autografts (a peroneal skin-muscle-skin autograft and a radial skin-fascia one in a 39-year-old female patient clinically diagnosed with carcinoma of the left mandibular alveolar ridge mucosa, Stage IVA (T4аN0M0.The Department of Microsurgery, P.A. Herzen Moscow Oncology Research Institute, Ministry of Health of Russia, has gained experience in comprehensively correcting extensive combined maxillofacial defects with two or more grafts in 27 patients who underwent autografting with a total of 73 flaps. The most functionally incapacitating and life-incompatible defect was removed at Stage 1 of reconstructive treatment. Delayed reconstruction was made after a complex of specialized antitumor therapy and assessment of treatment results in the absence of progressive growth. A great problem during multi-stage defect correction is presented by the lack of recipient vessels after cervical lymphadenectomy, the presence of soft tissue scar changes, trismus, temporomandibular joint ankylosis, contractures and displacement of the edges of the

Functional LH1 antenna complexes influence electron transfer in bacterial photosynthetic reaction centers

NARCIS (Netherlands)

Visschers, R.W.; Vulto, S.I.E.; Jones, M.R.; van Grondelle, R.; Kraayenhof, R.

1999-01-01

The effect of the light harvesting 1 (LH1) antenna complex on the driving force for light-driven electron transfer in the Rhodobacter sphaeroides reaction center has been examined. Equilibrium redox titrations show that the presence of the LH1 antenna complex influences the free energy change for

Functional LH1 antenna complexes influence electron transfer in bacterial photosynthetic reaction centers.

NARCIS (Netherlands)

Visschers, R.W.; Vulto, S.I.E.; Jones, M.R.; van Grondelle, R.; Kraayenhof, R.

1999-01-01

The effect of the light harvesting 1 (LH1) antenna complex on the driving force for light-driven electron transfer in the Rhodobacter sphaeroides reaction center has been examined. Equilibrium redox titrations show that the presence of the LH1 antenna complex influences the free energy change for

Angular detector of defects in a metallic tube by eddy currents

International Nuclear Information System (INIS)

Broudeur, R.

1990-01-01

The angular detector of defects in a metallic tube has two centering pieces for the clad positioning on both sides of a backing ring of the measuring coil. The inner diameter of the backing ring and the diameter of the centering pieces are in the ratio 4/3±0.6/3 and their axis are eccentric. This setting over associated at the guiding piece of the sheath in rotation gives at the measuring coil a functioning as a ponctual probe [fr

Defect complexes formed with Ag atoms in CDTE, ZnTe, and ZnSe

CERN Document Server

Wolf, H; Ostheimer, V; Hamann, J; Lany, S; Wichert, T

2000-01-01

Using the radioactive acceptor $^{111}\\!$Ag for perturbed $\\gamma$-$\\gamma$-angular correlation (PAC) spectroscopy for the first time, defect complexes formed with Ag are investigated in the II-VI semiconductors CdTe, ZnTe and ZnSe. The donors In, Br and the Te-vacancy were found to passivate Ag acceptors in CdTe via pair formation, which was also observed in In-doped ZnTe. In undoped or Sb-doped CdTe and in undoped ZnSe, the PAC experiments indicate the compensation of Ag acceptors by the formation of double broken bond centres, which are characterised by an electric field gradient with an asymmetry parameter close to h = 1. Additionally, a very large electric field gradient was observed in CdTe, which is possibly connected with residual impurities.

A Study of Defect Behavior in Almandine Garnet

Science.gov (United States)

Geiger, C. A.; Brearley, A. J.; Dachs, E.; Tipplet, G.; Rossman, G. R.

2016-12-01

Transport and diffusion in crystals are controlled by defects. However, a good understanding of the defect types in many silicates, including garnet, is not at hand. We undertook a study on synthetic almandine, ideal end-member Fe3Al2Si3O12, to better understand its precise chemical and physical properties and defect behavior. Crystals were synthesized at high pressures and temperatures under different fO2 conditions using various starting materials with H2O and without. The almandine obtained came in polycrystalline and single-crystal form. The synthetic reaction products and crystals were carefully characterized using X-ray powder diffraction, electron microprobe and TEM analysis and with 57Fe Mössbauer, UV/VIS single-crystal absorption and IR single-crystal spectroscopy. Various possible intrinsic defects, such as the Frenkel, Schottky and site-disorder types, along with Fe3+, in both synthetic and natural almandine crystals, were analyzed based on model defects expressed in Kröger-Vink notation. Certain types of minor microscopic- to macroscopic-sized precipitation or exsolution phases, including some that are nanosized, that are observed in synthetic almandine (e.g., magnetite), as well as in more compositionally complex natural crystals (e.g., magnetite, rutile, ilmenite), may result from defect reactions. An explanation for their origin through minor amounts of defects in garnet has certain advantages over other models that have been put forth in the literature that assume strict garnet stoichiometry for their formation and/or open-system atomic transport over relatively long length scales. Physical properties, including magnetic, electrical conductivity and diffusion behavior, as well as the color, of almandine are also analyzed in terms of various possible model defects. It is difficult, if not impossible, to synthesize stoichiometric end-member almandine, Fe3Al2Si3O12, in the laboratory, as small amounts of extrinsic OH- and/or Fe3+ defects, for example

Single d-metal atoms on F(s) and F(s+) defects of MgO(001): a theoretical study across the periodic table.

Science.gov (United States)

Neyman, Konstantin M; Inntam, Chan; Matveev, Alexei V; Nasluzov, Vladimir A; Rösch, Notker

2005-08-24

Single d-metal atoms on oxygen defects F(s) and F(s+) of the MgO(001) surface were studied theoretically. We employed an accurate density functional method combined with cluster models, embedded in an elastic polarizable environment, and we applied two gradient-corrected exchange-correlation functionals. In this way, we quantified how 17 metal atoms from groups 6-11 of the periodic table (Cu, Ag, Au; Ni, Pd, Pt; Co, Rh, Ir; Fe, Ru, Os; Mn, Re; and Cr, Mo, W) interact with terrace sites of MgO. We found bonding with F(s) and F(s+) defects to be in general stronger than that with O2- sites, except for Mn-, Re-, and Fe/F(s) complexes. In M/F(s) systems, electron density is accumulated on the metal center in a notable fashion. The binding energy on both kinds of O defects increases from 3d- to 4d- to 5d-atoms of a given group, at variance with the binding energy trend established earlier for the M/O2- complexes, 4d period, group 7 atoms are slightly destabilized compared to their group 6 congeners in both the F(s) and F(s+) complexes; for later transition elements, the binding energy increases gradually up to group 10 and finally decreases again in group 11, most strongly on the F(s) site. This trend is governed by the negative charge on the adsorbed atoms. We discuss implications for an experimental detection of metal atoms on oxide supports based on computed core-level energies.

A molecular dynamics simulation study of irradiation induced defects in gold nanowire

Science.gov (United States)

Liu, Wenqiang; Chen, Piheng; Qiu, Ruizhi; Khan, Maaz; Liu, Jie; Hou, Mingdong; Duan, Jinglai

2017-08-01

Displacement cascade in gold nanowires was studied using molecular dynamics computer simulations. Primary knock-on atoms (PKAs) with different kinetic energies were initiated either at the surface or at the center of the nanowires. We found three kinds of defects that were induced by the cascade, including point defects, stacking faults and crater at the surface. The starting points of PKAs influence the number of residual point defects, and this consequently affect the boundary of anti-radiation window which was proposed by calculation of diffusion of point defects to the free surface of nanowires. Formation of stacking faults that expanded the whole cross-section of gold nanowires was observed when the PKA's kinetic energy was higher than 5 keV. Increasing the PKA's kinetic energy up to more than 10 keV may lead to the formation of crater at the surface of nanowires due to microexplosion of hot atoms. At this energy, PKAs started from the center of nanowires can also result in the creation of crater because length of cascade region is comparable to diameter of nanowires. Both the two factors, namely initial positions of PKAs as well as the craters induced by higher energy irradiation, would influence the ability of radiation resistance of metal nanowires.

Subsurface defects structural evolution in nano-cutting of single crystal copper

International Nuclear Information System (INIS)

Wang, Quanlong; Bai, Qingshun; Chen, Jiaxuan; Sun, Yazhou; Guo, Yongbo; Liang, Yingchun

2015-01-01

Highlights: • An innovative analysis method is adopted to analyze nano-cutting process accurately. • A characteristic SFT and stair-rod dislocation are found in subsurface defect layer. • The formation mechanism of stair-rod dislocation is investigated. • The local atomic structure of subsurface defects is introduced. - Abstract: In this work, molecular dynamics simulation is performed to study the subsurface defects structural distribution and its evolution during nano-cutting process of single crystal copper. The formation mechanism of chip and machined surface is interviewed by analyzing the dislocation evolution and atomic migration. The centro-symmetry parameter and spherical harmonics method are adopted to characterize the distribution and evolution of the subsurface defect structures and local atomic structures. The results show that stacking faults, dislocation loops, “V-shaped” dislocation loops, and plenty of point defects are formed during the machined surface being formed in shear-slip zone. In subsurface damage layers, stair-rod dislocation, stacking fault tetrahedra, atomic cluster defect, and vacancy defect are formed. And the formation mechanism of stair-rod dislocation is investigated by atomic-scale structure evolution. The local atomic structures of subsurface defects are icosahedrons, hexagonal close packed, body-centered cubic, and defect face center cubic, and the variations of local atomic structures are investigated

Subsurface defects structural evolution in nano-cutting of single crystal copper

Energy Technology Data Exchange (ETDEWEB)

Wang, Quanlong [School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China); Center for Precision Engineering, Harbin Institute of Technology, Harbin 150001 (China); Bai, Qingshun [School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China); Chen, Jiaxuan, E-mail: wangquanlong0@hit.edu.cn [Center for Precision Engineering, Harbin Institute of Technology, Harbin 150001 (China); Sun, Yazhou [School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China); Guo, Yongbo [Center for Precision Engineering, Harbin Institute of Technology, Harbin 150001 (China); Liang, Yingchun [School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China)

2015-07-30

Highlights: • An innovative analysis method is adopted to analyze nano-cutting process accurately. • A characteristic SFT and stair-rod dislocation are found in subsurface defect layer. • The formation mechanism of stair-rod dislocation is investigated. • The local atomic structure of subsurface defects is introduced. - Abstract: In this work, molecular dynamics simulation is performed to study the subsurface defects structural distribution and its evolution during nano-cutting process of single crystal copper. The formation mechanism of chip and machined surface is interviewed by analyzing the dislocation evolution and atomic migration. The centro-symmetry parameter and spherical harmonics method are adopted to characterize the distribution and evolution of the subsurface defect structures and local atomic structures. The results show that stacking faults, dislocation loops, “V-shaped” dislocation loops, and plenty of point defects are formed during the machined surface being formed in shear-slip zone. In subsurface damage layers, stair-rod dislocation, stacking fault tetrahedra, atomic cluster defect, and vacancy defect are formed. And the formation mechanism of stair-rod dislocation is investigated by atomic-scale structure evolution. The local atomic structures of subsurface defects are icosahedrons, hexagonal close packed, body-centered cubic, and defect face center cubic, and the variations of local atomic structures are investigated.

Neuroradiologic findings in children with mitochondrial disorder: correlation with mitochondrial respiratory chain defects

International Nuclear Information System (INIS)

Kim, Jinna; Lee, Seung-Koo; Kim, Dong Ik; Kim, Eung Yeop; Lee, Young-Mock; Lee, Joon Soo; Kim, Heung Dong

2008-01-01

Mitochondrial disorders are a heterogeneous group of disorders affecting energy metabolism that can present at any age with a wide variety of clinical symptoms. We investigated brain magnetic resonance (MR) findings in 40 children with defects of the mitochondrial respiratory chain (MRC) complex and correlated them with the type of MRC defects. Enrolled were 40 children with MRC defects in biochemical enzyme assay of the muscle specimen. Twenty-one children were found to have classical syndromes of mitochondrial disorders and 19 children presented nonspecific mitochondrial encephalomyopathies. Their brain MR imaging findings were retrospectively reviewed and correlated with the biochemical defect in the MRC complex. Children with MRC defects showed various neuroradiologic features on brain MR imaging that resulted from a complex genetic background and a heterogeneous phenotype. Rapid progression of atrophy involving all structures of the brain with variable involvement of deep gray and white matter are the most frequent MR findings in children with MRC defects in both classical syndromes of mitochondrial disorder and nonspecific mitochondrial encephalomyopathies. The type of biochemical defect in the MRC complex enzyme did not correlate with brain MR findings in child patients. (orig.)

Neuroradiologic findings in children with mitochondrial disorder: correlation with mitochondrial respiratory chain defects

Energy Technology Data Exchange (ETDEWEB)

Kim, Jinna; Lee, Seung-Koo; Kim, Dong Ik [Yonsei University College of Medicine, Department of Radiology, Research Institute of Radiological Science, Seoul (Korea); Kim, Eung Yeop [Yonsei University College of Medicine, Department of Radiology, Research Institute of Radiological Science, Brain Korea 21 Project for Medical Science, Seoul (Korea); Lee, Young-Mock; Lee, Joon Soo [Yonsei University College of Medicine, Department of Pediatrics, Pediatric Epilepsy Clinics, Severance Children' s Hospital, Brain Research Institute, Seoul (Korea); Kim, Heung Dong [Yonsei University College of Medicine, Department of Pediatrics, Pediatric Epilepsy Clinics, Severance Children' s Hospital, Brain Research Institute, Seoul (Korea); Yonsei University College of Medicine, Department of Pediatrics, Seoul (Korea)

2008-08-15

Mitochondrial disorders are a heterogeneous group of disorders affecting energy metabolism that can present at any age with a wide variety of clinical symptoms. We investigated brain magnetic resonance (MR) findings in 40 children with defects of the mitochondrial respiratory chain (MRC) complex and correlated them with the type of MRC defects. Enrolled were 40 children with MRC defects in biochemical enzyme assay of the muscle specimen. Twenty-one children were found to have classical syndromes of mitochondrial disorders and 19 children presented nonspecific mitochondrial encephalomyopathies. Their brain MR imaging findings were retrospectively reviewed and correlated with the biochemical defect in the MRC complex. Children with MRC defects showed various neuroradiologic features on brain MR imaging that resulted from a complex genetic background and a heterogeneous phenotype. Rapid progression of atrophy involving all structures of the brain with variable involvement of deep gray and white matter are the most frequent MR findings in children with MRC defects in both classical syndromes of mitochondrial disorder and nonspecific mitochondrial encephalomyopathies. The type of biochemical defect in the MRC complex enzyme did not correlate with brain MR findings in child patients. (orig.)

Tibial and fibular developmental fields defects

International Nuclear Information System (INIS)

Khoury, N.J.; Haddad, M.C.; Hourani, M.H.

1999-01-01

Malformations of the lower limbs are rare and heterogeneous anomalies. To explain the diversity and complexity of these abnormalities, authors introduced the concept of tibial and fibular developmental fields. Defects in these fields are responsible for different malformations, which have been described, to our knowledge, in only one report in the radiology literature. We present a case of a newborn with femoral bifurcation, absent fibulae and talar bones, ankle and foot malformations, and associated atrial septal defect. Our case is an example of defects in both fibular and tibial developmental fields. (orig.)

Improving Defect-Based Quantum Emitters in Silicon Carbide via Inorganic Passivation.

Science.gov (United States)

Polking, Mark J; Dibos, Alan M; de Leon, Nathalie P; Park, Hongkun

2018-01-01

Defect-based color centers in wide-bandgap crystalline solids are actively being explored for quantum information science, sensing, and imaging. Unfortunately, the luminescent properties of these emitters are frequently degraded by blinking and photobleaching that arise from poorly passivated host crystal surfaces. Here, a new method for stabilizing the photoluminescence and charge state of color centers based on epitaxial growth of an inorganic passivation layer is presented. Specifically, carbon antisite-vacancy pairs (CAV centers) in 4H-SiC, which serve as single-photon emitters at visible wavelengths, are used as a model system to demonstrate the power of this inorganic passivation scheme. Analysis of CAV centers with scanning confocal microscopy indicates a dramatic improvement in photostability and an enhancement in emission after growth of an epitaxial AlN passivation layer. Permanent, spatially selective control of the defect charge state can also be achieved by exploiting the mismatch in spontaneous polarization at the AlN/SiC interface. These results demonstrate that epitaxial inorganic passivation of defect-based quantum emitters provides a new method for enhancing photostability, emission, and charge state stability of these color centers. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Study of new complexes of uranium and comba radical. I.- Complexes defective in sodium carbonate; Estudio de nuevos complejos entre el uranio y el radical CDMBA. I. Complejos con defectos de carbonato sodico

Energy Technology Data Exchange (ETDEWEB)

Vera Palomino, J; Galiano Sedano, J A; Parellada Bellod, R; Bellido Gonzalez, A

1975-07-01

Some complexes formed in presence of defect of sodium carbonate with respect to the stoichiometric ratio (U): (C0{sub 3}) = 1:3 are studied. This ratio corresponds to the main complex which is responsible for the uranium extraction with CDMBAC organic solutions and from U(VI) aqueous solutions with an excess of sodium carbonate. (Author) 10 refs.

VV and VO2 defects in silicon studied with hybrid density functional theory

KAUST Repository

Christopoulos, Stavros Richard G

2014-12-07

The formation of VO (A-center), VV and VO2 defects in irradiated Czochralski-grown silicon (Si) is of technological importance. Recent theoretical studies have examined the formation and charge states of the A-center in detail. Here we use density functional theory employing hybrid functionals to analyze the formation of VV and VO2 defects. The formation energy as a function of the Fermi energy is calculated for all possible charge states. For the VV and VO2 defects double negatively charged and neutral states dominate, respectively.

A magnetically tunable non-Bragg defect mode in a corrugated waveguide filled with liquid crystals

Science.gov (United States)

Zhang, Lu; Fan, Ya-Xian; Liu, Huan; Han, Xu; Lu, Wen-Qiang; Tao, Zhi-Yong

2018-04-01

A magnetically tunable, non-Bragg defect mode (NBDM) was created in the terahertz frequency range by inserting a defect in the middle of a periodically corrugated waveguide filled with liquid crystals (LCs). In the periodic waveguide, non-Bragg gaps beyond the Bragg ones, which appear in the transmission spectra, are created by different transverse mode resonances. The transmission spectra of the waveguide containing a defect showed that a defect mode was present inside the non-Bragg gap. The NBDM has quite different features compared to the Bragg defect mode, which includes more complex, high-order guided wave modes. In our study, we filled the corrugated waveguide with LCs to realize the tunability of the NBDM. The simulated results showed that the NBDM in a corrugated waveguide filled with LCs can be used in filters, sensors, switches, and other terahertz integrated devices.

Defect identification in semiconductors with positron annihilation: experiment and theory

Science.gov (United States)

Tuomisto, Filip

2015-03-01

Positron annihilation spectroscopy is a very powerful technique for the detection, identification and quantification of vacancy-type defects in semiconductors. In the past decades, it has been used to reveal the relationship between opto-electronic properties and specific defects in a wide variety of materials - examples include parasitic yellow luminescence in GaN, dominant acceptor defects in ZnO and broad-band absorption causing brown coloration in natural diamond. In typical binary compound semiconductors, the selective sensitivity of the technique is rather strongly limited to cation vacancies that possess significant open volume and suitable charge (negative of neutral). On the other hand, oxygen vacancies in oxide semiconductors are a widely debated topic. The properties attributed to oxygen vacancies include the inherent n-type conduction, poor p-type dopability, coloration (absorption), deep level luminescence and non-radiative recombination, while the only direct experimental evidence of their existence has been obtained on the crystal surface. We will present recent advances in combining state-of-the-art positron annihilation experiments and ab initio computational approaches. The latter can be used to model both the positron lifetime and the electron-positron momentum distribution - quantities that can be directly compared with experimental results. We have applied these methods to study vacancy-type defects in III-nitride semiconductors (GaN, AlN, InN) and oxides such as ZnO, SnO2, In2O3andGa2O3. We will show that cation-vacancy-related defects are important compensating centers in all these materials when they are n-type. In addition, we will show that anion (N, O) vacancies can be detected when they appear as complexes with cation vacancies.

A quantum-chemical study of oxygen-vacancy defects in PbTiO3 crystals

International Nuclear Information System (INIS)

Stashans, Arvids; Serrano, Sheyla; Medina, Paul

2006-01-01

Investigation of an oxygen vacancy and F center in the cubic and tetragonal lattices of PbTiO 3 crystals is done by means of quantum-chemical simulations. Displacements of defect-surrounding atoms, electronic and optical properties, lattice relaxation energies and some new effects due to the defects presence are reported and analyzed. A comparison with similar studies is made and conclusions are drawn on the basis of the obtained results

Repairing Nanoparticle Surface Defects.

Science.gov (United States)

Marino, Emanuele; Kodger, Thomas E; Crisp, Ryan W; Timmerman, Dolf; MacArthur, Katherine E; Heggen, Marc; Schall, Peter

2017-10-23

Solar devices based on semiconductor nanoparticles require the use of conductive ligands; however, replacing the native, insulating ligands with conductive metal chalcogenide complexes introduces structural defects within the crystalline nanostructure that act as traps for charge carriers. We utilized atomically thin semiconductor nanoplatelets as a convenient platform for studying, both microscopically and spectroscopically, the development of defects during ligand exchange with the conductive ligands Na 4 SnS 4 and (NH 4 ) 4 Sn 2 S 6 . These defects can be repaired via mild chemical or thermal routes, through the addition of L-type ligands or wet annealing, respectively. This results in a higher-quality, conductive, colloidally stable nanomaterial that may be used as the active film in optoelectronic devices. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Isotopic fingerprints of gold-containing luminescence centers in 28Si

CERN Document Server

Steger, M; Sekiguchi, T; Saeedi, K; Thewalt, M L W; Henry, M O; Johnston, K; Riemann, H; Abrosimov, N V; Churbanov,; Gusev, A V; Bulanov, A D; Kaliteevski, I D; Godisov, O N; Becker, P; Pohl, H J

2009-01-01

We have recently shown that the dramatic reduction in linewidth of many deep luminescence centers in highly enriched 28Si can lead to the observation of isotopic fingerprints, revealing not only that a specific element is involved in the defect complex, but also the number of atoms of that element. This has led to many surprises regarding the actual constituents of supposedly well known luminescence centers, as well as the discovery of new members of a family of four-atom centers where the constituents can be chosen from Cu, Ag, Au and Li. Obtaining the isotopic fingerprint of Au is problematic, since only 197Au is stable, but we have now used the relatively long-lived 195Au to reveal the presence, and the number, of Au atoms in several of these centers. We find a series of four-atom centers containing one Au plus Cu and/or Li. Surprisingly, the Au isotopic fingerprint also reveals a series of five-atom centers containing a single Au plus Cu and/or Li. Further evidence for the ubiquity of these four- and five...

Defect branes as Alice strings

International Nuclear Information System (INIS)

Okada, Takashi; Sakatani, Yuho

2015-01-01

There exist various defect-brane backgrounds in supergravity theories which arise as the low energy limit of string theories. These backgrounds typically have non-trivial monodromies, and if we move a charged probe around the center of a defect, its charge will be changed by the action of the monodromy. During the process, the charge conservation law seems to be violated. In this paper, to resolve this puzzle, we examine a dynamics of the charge changing process and show that the missing charge of the probe is transferred to the background. We then explicitly construct the resultant background after the charge transfer process by utilizing dualities. This background has the same monodromy as the original defect brane, but has an additional charge which does not have any localized source. In the literature, such a charge without localized source is known to appear in the presence of Alice strings. We argue that defect branes can in fact be regarded as a realization of Alice strings in string theory and examine the charge transfer process from that perspective.

Defect branes as Alice strings

Energy Technology Data Exchange (ETDEWEB)

Okada, Takashi [Theoretical Biology Laboratory, RIKEN,Wako 351-0198 (Japan); Sakatani, Yuho [Department of Physics and Astronomy,Seoul National University, Seoul 151-747 (Korea, Republic of)

2015-03-25

There exist various defect-brane backgrounds in supergravity theories which arise as the low energy limit of string theories. These backgrounds typically have non-trivial monodromies, and if we move a charged probe around the center of a defect, its charge will be changed by the action of the monodromy. During the process, the charge conservation law seems to be violated. In this paper, to resolve this puzzle, we examine a dynamics of the charge changing process and show that the missing charge of the probe is transferred to the background. We then explicitly construct the resultant background after the charge transfer process by utilizing dualities. This background has the same monodromy as the original defect brane, but has an additional charge which does not have any localized source. In the literature, such a charge without localized source is known to appear in the presence of Alice strings. We argue that defect branes can in fact be regarded as a realization of Alice strings in string theory and examine the charge transfer process from that perspective.

Interference effect on annealing temperature of A and E centers in silicon.

Science.gov (United States)

Fang, P. H.; Tanaka, T.

1971-01-01

The significance of recent experimental observations on the annealing defects in n-type silicon has been examined. The observed anomalous annealing temperatures of A and E centers and their impurity concentration dependence are explained by an interference between the two centers.

First-principles study of point defects in CePO{sub 4} monazite

Energy Technology Data Exchange (ETDEWEB)

Yi, Yong; Zhao, Xiaofeng [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); Teng, Yuancheng, E-mail: tyc239@163.com [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); Bi, Beng [Joint Laboratory for Extreme Conditions Matter Properties, Southwest University of Science and Technology, Mianyang 621010 (China); Wang, Lili [Institute of Computer Application, China Academy of Engineering Physics, Mianyang 621900 (China); Wu, Lang; Zhang, Kuibao [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China)

2016-12-15

CePO{sub 4} monazite is an important radiation-resistant material that may act as a potential minor actinides waste form. Here, we present the results of the calculations for the basic radiation defect modellings in CePO{sub 4} crystals, along with the examination of their defect formation energies and effect of the defect concentrations. This study focused on building a fully-relaxed CePO{sub 4} model with the step iterative optimization from the DFT-GGA calculations using the VASP and CASTEP databases. The results show that the Frenkel defect configuration resulting from the center interstitials has a lower energy when compared to two adjacent orthophosphate centers (the saddle point position). High formation energies were found for all the types of intrinsic Frenkel and vacancy defects. The formation energies conform to the following trend (given in the decreasing order of energy): Ce Frenkel (12.41 eV) > O Frenkel (11.02 eV) > Ce vacancy (9.09 eV) > O vacancy (6.69 eV). We observed almost no effect from the defect concentrations on the defect formation energies.

Detection of oxygen-related defects in GaAs by exo-electron emission spectroscopy

International Nuclear Information System (INIS)

Hulluvarad, Shiva S.; Naddaf, M.; Bhoraskar, S.V.

2001-01-01

The influence of intentional introduction of oxygen, at the surface of GaAs, on its native surface states was studied. Oxygen was made to interact with the surface of GaAs by three different means: (1) by growing native oxides, (2) exposing to oxygen plasma in an electron cyclotron resonance (ECR) plasma reactor and by (3) high energy oxygen ion irradiation. Thermally stimulated exo-electron emission (TSEE) spectroscopy was used to estimate the relative densities and energies of the surface states induced by the three different modes of introducing oxygen. Out of the two native defect levels found in GaAs by TSEE; at 325 K (0.7 eV below E c ) and at 415 K (0.9 below E c ); the former is seen to get broadened or split into multiple peaks in each of the methods. Multiple peaks in TSEE signify the presence of a closely spaced band of defect levels. Therefore the results exclusively point out that oxygen-related complexes contribute to the formation of a band of defects centered at 325 K in TSEE which is correlated to an energy level 0.7 eV below E c known as the EL2 defect level. The results reported in this paper thus confirm that the TSEE peak at 0.7 eV below E c is related to oxygen induced defects whereas the peak at 0.9 eV is not affected by the presence of oxygen-related species

Detection of oxygen-related defects in GaAs by exo-electron emission spectroscopy

Science.gov (United States)

Hulluvarad, Shiva S.; Naddaf, M.; Bhoraskar, S. V.

2001-10-01

The influence of intentional introduction of oxygen, at the surface of GaAs, on its native surface states was studied. Oxygen was made to interact with the surface of GaAs by three different means: (1) by growing native oxides, (2) exposing to oxygen plasma in an electron cyclotron resonance (ECR) plasma reactor and by (3) high energy oxygen ion irradiation. Thermally stimulated exo-electron emission (TSEE) spectroscopy was used to estimate the relative densities and energies of the surface states induced by the three different modes of introducing oxygen. Out of the two native defect levels found in GaAs by TSEE; at 325 K (0.7 eV below Ec) and at 415 K (0.9 below Ec); the former is seen to get broadened or split into multiple peaks in each of the methods. Multiple peaks in TSEE signify the presence of a closely spaced band of defect levels. Therefore the results exclusively point out that oxygen-related complexes contribute to the formation of a band of defects centered at 325 K in TSEE which is correlated to an energy level 0.7 eV below Ec known as the EL2 defect level. The results reported in this paper thus confirm that the TSEE peak at 0.7 eV below Ec is related to oxygen induced defects whereas the peak at 0.9 eV is not affected by the presence of oxygen-related species.

Detection of oxygen-related defects in GaAs by exo-electron emission spectroscopy

International Nuclear Information System (INIS)

Hulluvarad, Shiva S.; Naddaf, M.; Bhoraskar, S.V.

2004-01-01

The influence of intentional introduction of oxygen, at the surface of GaAs, on its native surface states was studied. Oxygen was made to interact with the surface of GaAs by three different means: (1) by growing native oxides, (2) exposing to oxygen plasma in an electron cyclotron resonance (ECR) plasma reactor and by (3) high energy oxygen ion irradiation. Thermally stimulated exo-electron emission (TSEE) spectroscopy was used to estimate the relative densities and energies of the surface states induced by the three different modes of introducing oxygen. Out of the two native defect levels found in GaAs by TSEE; at 325 K (0.7 eV below E c ) and at 415 K (0.9 below E c ); the former is seen to get broadened or split into multiple peaks in each of the methods. Multiple peaks in TSEE signify the presence of a closely spaced band of defect levels. Therefore the results exclusively point out that oxygen-related complexes contribute to the formation of a band of defects centered at 325 K in TSEE which is correlated to an energy level 0.7 eV below E c known as the EL2 defect level. The results reported in this paper thus confirm that the TSEE peak at 0.7 eV below E c is related to oxygen induced defects whereas the peak at 0.9 eV is not affected by the presence of oxygen-related species. (author)

Limb-body wall defect: experience of a reference service of fetal medicine from Southern Brazil.

Science.gov (United States)

Gazolla, Ana C; da Cunha, André C; Telles, Jorge A B; Betat, Rosilene da S; Romano, Mayara A; Marshall, Isabel; Gobatto, Amanda M; de H Bicca, Anna M; Arcolini, Camila P; Dal Pai, Thaís K V; Vieira, Luciane R; Targa, Luciano V; Betineli, Ildo; Zen, Paulo R G; Rosa, Rafael F M

2014-10-01

Limb-body wall defect is a rare condition characterized by a combination of large and complex defects of the ventral thorax and abdominal wall with craniofacial and limb anomalies. The aim of this study was to describe the experience of our fetal medicine service, a reference from Southern Brazil, with prenatally diagnosed patients with a limb-body wall defect in a 3 years period. Only patients who fulfilled the criteria suggested by Hunter et al. (2011) were included in the study. Clinical data and results of radiological and cytogenetic evaluation were collected from their medical records. Our sample was composed of 8 patients. Many of their mothers were younger than 25 years (50%) and in their first pregnancy (62.5%). It is noteworthy that one patient was referred due to suspected anencephaly and another due to a twin pregnancy with an embryonic sac. Craniofacial defects were verified in three patients (37.5%), thoracic/abdominal abnormalities in 6 (75%) and limb defects in eight (100%). Congenital heart defects were observed in five patients (62.5%). One of them presented a previously undescribed complex heart defect. The results disclosed that complementary exams, such as MRI and echocardiography, are important to better define the observed defects. Some of them, such as congenital heart defects, may be more common than previously reported. This definition is essential for the proper management of the pregnancy and genetic counseling of the family. The birth of these children must be planned with caution and for the prognosis a long survival possibility, despite unlikely and rare, must be considered. © 2014 Wiley Periodicals, Inc.

Molecular Epidemiology and Clinical Impact of Acinetobacter calcoaceticus-baumannii Complex in a Belgian Burn Wound Center.

Directory of Open Access Journals (Sweden)

Daniel De Vos

Full Text Available Multidrug resistant Acinetobacter baumannii and its closely related species A. pittii and A. nosocomialis, all members of the Acinetobacter calcoaceticus-baumannii (Acb complex, are a major cause of hospital acquired infection. In the burn wound center of the Queen Astrid military hospital in Brussels, 48 patients were colonized or infected with Acb complex over a 52-month period. We report the molecular epidemiology of these organisms, their clinical impact and infection control measures taken. A representative set of 157 Acb complex isolates was analyzed using repetitive sequence-based PCR (rep-PCR (DiversiLab and a multiplex PCR targeting OXA-51-like and OXA-23-like genes. We identified 31 rep-PCR genotypes (strains. Representatives of each rep-type were identified to species by rpoB sequence analysis: 13 types to A. baumannii, 10 to A. pittii, and 3 to A. nosocomialis. It was assumed that isolates that belonged to the same rep-type also belonged to the same species. Thus, 83.4% of all isolates were identified to A. baumannii, 9.6% to A. pittii and 4.5% to A. nosocomialis. We observed 12 extensively drug resistant Acb strains (10 A. baumannii and 2 A. nosocomialis, all carbapenem-non-susceptible/colistin-susceptible and imported into the burn wound center through patients injured in North Africa. The two most prevalent rep-types 12 and 13 harbored an OXA-23-like gene. Multilocus sequence typing allocated them to clonal complex 1 corresponding to EU (international clone I. Both strains caused consecutive outbreaks, interspersed with periods of apparent eradication. Patients infected with carbapenem resistant A. baumannii were successfully treated with colistin/rifampicin. Extensive infection control measures were required to eradicate the organisms. Acinetobacter infection and colonization was not associated with increased attributable mortality.

Molecular Epidemiology and Clinical Impact of Acinetobacter calcoaceticus-baumannii Complex in a Belgian Burn Wound Center

Science.gov (United States)

Bilocq, Florence; Jennes, Serge; Verbeken, Gilbert; Rose, Thomas; Keersebilck, Elkana; Bosmans, Petra; Pieters, Thierry; Hing, Mony; Heuninckx, Walter; De Pauw, Frank; Soentjens, Patrick; Merabishvili, Maia; Deschaght, Pieter; Vaneechoutte, Mario; Bogaerts, Pierre; Glupczynski, Youri; Pot, Bruno; van der Reijden, Tanny J.; Dijkshoorn, Lenie

2016-01-01

Multidrug resistant Acinetobacter baumannii and its closely related species A. pittii and A. nosocomialis, all members of the Acinetobacter calcoaceticus-baumannii (Acb) complex, are a major cause of hospital acquired infection. In the burn wound center of the Queen Astrid military hospital in Brussels, 48 patients were colonized or infected with Acb complex over a 52-month period. We report the molecular epidemiology of these organisms, their clinical impact and infection control measures taken. A representative set of 157 Acb complex isolates was analyzed using repetitive sequence-based PCR (rep-PCR) (DiversiLab) and a multiplex PCR targeting OXA-51-like and OXA-23-like genes. We identified 31 rep-PCR genotypes (strains). Representatives of each rep-type were identified to species by rpoB sequence analysis: 13 types to A. baumannii, 10 to A. pittii, and 3 to A. nosocomialis. It was assumed that isolates that belonged to the same rep-type also belonged to the same species. Thus, 83.4% of all isolates were identified to A. baumannii, 9.6% to A. pittii and 4.5% to A. nosocomialis. We observed 12 extensively drug resistant Acb strains (10 A. baumannii and 2 A. nosocomialis), all carbapenem-non-susceptible/colistin-susceptible and imported into the burn wound center through patients injured in North Africa. The two most prevalent rep-types 12 and 13 harbored an OXA-23-like gene. Multilocus sequence typing allocated them to clonal complex 1 corresponding to EU (international) clone I. Both strains caused consecutive outbreaks, interspersed with periods of apparent eradication. Patients infected with carbapenem resistant A. baumannii were successfully treated with colistin/rifampicin. Extensive infection control measures were required to eradicate the organisms. Acinetobacter infection and colonization was not associated with increased attributable mortality. PMID:27223476

Automatic classification of blank substrate defects

Science.gov (United States)

Boettiger, Tom; Buck, Peter; Paninjath, Sankaranarayanan; Pereira, Mark; Ronald, Rob; Rost, Dan; Samir, Bhamidipati

2014-10-01

Technology Center (MPMask). The Calibre ADC tool was qualified on production mask blanks against the manual classification. The classification accuracy of ADC is greater than 95% for critical defects with an overall accuracy of 90%. The sensitivity to weak defect signals and locating the defect in the images is a challenge we are resolving. The performance of the tool has been demonstrated on multiple mask types and is ready for deployment in full volume mask manufacturing production flow. Implementation of Calibre ADC is estimated to reduce the misclassification of critical defects by 60-80%.

Anelastic relaxation of interstitial foreign atoms and their complexes with intrinsic defects in B.C.C. metals

International Nuclear Information System (INIS)

Weller, M.

1985-01-01

In body-centred cubic metals, heavy interstitial foreign atoms (IFA) O, N and C give rise to relaxations of Snoek type. For dilute alloys, relaxation parameters are summarized. In concentrated alloys (group Va metals containing O or N) Snoek relaxations are influenced by the interaction of IFA. The recent controversy is discussed as to whether this interaction is based on clustering or anticlustering. In irradiated metals complexes of IFA with intrinsic atomic defects (vacancies or self interstitial atoms) also give rise to relaxations

Defect States Emerging from a Non-Hermitian Flatband of Photonic Zero Modes

Science.gov (United States)

Qi, Bingkun; Zhang, Lingxuan; Ge, Li

2018-03-01

We show the existence of a flatband consisting of photonic zero modes in a gain and loss modulated lattice system as a result of the underlying non-Hermitian particle-hole symmetry. This general finding explains the previous observation in parity-time symmetric systems where non-Hermitian particle-hole symmetry is hidden. We further discuss the defect states in these systems, whose emergence can be viewed as an unconventional alignment of a pseudospin under the influence of a complex-valued pseudomagnetic field. These defect states also behave as a chain with two types of links, one rigid in a unit cell and one soft between unit cells, as the defect states become increasingly localized with the gain and loss strength.

Repair of tetralogy of Fallot associated with atrioventricular septal defect.

Science.gov (United States)

Tláskal, T; Hucín, B; Kostelka, M; Chaloupecký, V; Marek, J; Tax, P; Janouàek, J; Kuèera, V; Hruda, J; Reich, O; Skovránek, J

1998-01-01

Tetralogy of Fallot, when associated with atrioventricular septal defect permitting shunting at ventricular level, represents a complex cyanotic congenital malformation. Experience with surgical repair is limited, and results vary considerably. Between 1984 and 1996, we repaired 14 consecutive patients with this combination seen in our center. Their ages ranged from 8 months to 21 years (median 7.4 years). Six (42.9%) had Down's syndrome. In eight patients the correct diagnosis was made using echocardiography alone. In the remaining six patients, who had previously-constructed arterial shunts and/or suspected pulmonary arterial stenosis, catheterization and angiocardiography were also performed. The repair consisted of double patch closure of the septal defect, reconstruction of two atrioventricular orifices, and relief of pulmonary stenosis at all levels. In five patients with a hypoplastic pulmonary trunk, a monocusp transannular patch (four patients) or an allograft (one patient) was used for restoration of continuity from the right ventricle to the pulmonary arteries. Patch enlargement of one or both pulmonary arteries was necessary in five patients. One patient (7.1%) died early, and another late. The twelve surviving (85.8%) patients have been followed for 1.2-12.5 years after surgery (median 4.9 years, mean 5.9+/-3.9 years). During the follow-up, reoperation was necessary for repair of residual ventricular septal defect and pulmonary regurgitation in two patients, and closure of an atrial septal defect and alteration to left atrioventricular valvar regurgitation in one patient. Seven patients are in class I of the New York Heart Association, four in class II, and one in class III. Tetralogy of Fallot associated with atrioventricular septal defect can be corrected with low mortality and good long-term results. Residual lesions, however, have a tendency to progress, especially when seen in combination. After surgery, all patients need long-term close follow-up.

Sirenomelia: A Multi-systemic Polytopic Field Defect with Ongoing Controversies.

Science.gov (United States)

Boer, Lucas L; Morava, Eva; Klein, Willemijn M; Schepens-Franke, Annelieke N; Oostra, Roelof Jan

2017-06-01

The most impressive phenotypic appearance of sirenomelia is the presence of a 180°-rotated, axially positioned, single lower limb. Associated gastrointestinal and genitourinary anomalies are almost always present. This rare anomaly is still the subject of ongoing controversies concerning its nosology, pathogenesis, and possible genetic etiology. Sirenomelia can be part of a syndromic continuum, overlapping with other complex conditions including caudal dysgenesis and VATER/VACTERL/VACTERL-H associations, which could all be part of a heterogeneous spectrum, and originate from an early defect in blastogenesis. It is imaginable that different "primary field defects," whether or not genetically based, induce a spectrum of caudal malformations. In the current study, we review the contemporary hypotheses and conceptual approaches regarding the etiology and pathogenesis of sirenomelia, especially in the context of concomitant conditions. To expand on the latter, we included the external and internal dysmorphology of one third trimester sirenomelic fetus from our anatomical museum collection, in which multiple concomitant but discordant anomalies were observed compared with classic sirenomelia, and was diagnosed as VACTERL-H association with sirenomelia. Birth Defects Research 109:791-804, 2017. © 2017 The Authors. Birth Defects Research Published by Wiley Periodicals, Inc. © 2017 The Authors. Birth Defects Research Published by Wiley Periodicals, Inc.

DX centers in III-V semiconductors under hydrostatic pressure

International Nuclear Information System (INIS)

Wolk, J.A.

1992-11-01

DX centers are deep level defects found in some III-V semiconductors. They have persistent photoconductivity and large difference between thermal and optical ionization energies. Hydrostatic pressure was used to study microstructure of these defects. A new local vibrational mode (LVM) was observed in hydrostatically stressed, Si-doped GaAs. Corresponding infrared absorption peak is distinct from the Si Ga shallow donor LVM peak, which is the only other LVM peak observed in our samples, and is assigned to the Si DX center. Analysis of the relative intensities of the Si DX LVM and the Si shallow donor LVM peaks, combined with Hall effect and resistivity indicate that the Si DX center is negatively charged. Frequency of this new mode provides clues to the structure of this defect. A pressure induced deep donor level in S-doped InP was also discovered which has the properties of a DX center. Pressure at which the new defect becomes more stable than the shallow donor is 82 kbar. Optical ionization energy and energy dependence of the optical absorption cross section was measured for this new effect. Capture barrier from the conduction band into the DX state were also determined. That DX centers can be formed in InP by pressure suggests that DX states should be common in n-type III-V semiconductors. A method is suggested for predicting under what conditions these defects will be the most stable form of the donor impurity

Improving surface and defect center chemistry of fluorescent nanodiamonds for imaging purposes-a review

NARCIS (Netherlands)

Nagl, Andreas; Hemelaar, Simon Robert; Schirhagl, Romana

2015-01-01

Diamonds are widely used for jewelry owing to their superior optical properties accounting for their fascinating beauty. Beyond the sparkle, diamond is highly investigated in materials science for its remarkable properties. Recently, fluorescent defects in diamond, particularly the negatively

Disclinations, dislocations, and continuous defects: A reappraisal

Science.gov (United States)

Kleman, M.; Friedel, J.

2008-01-01

Disclinations were first observed in mesomorphic phases. They were later found relevant to a number of ill-ordered condensed-matter media involving continuous symmetries or frustrated order. Disclinations also appear in polycrystals at the edges of grain boundaries; but they are of limited interest in solid single crystals, where they can move only by diffusion climb and, owing to their large elastic stresses, mostly appear in close pairs of opposite signs. The relaxation mechanisms associated with a disclination in its creation, motion, and change of shape involve an interplay with continuous or quantized dislocations and/or continuous disclinations. These are attached to the disclinations or are akin to Nye’s dislocation densities, which are particularly well suited for consideration here. The notion of an extended Volterra process is introduced, which takes these relaxation processes into account and covers different situations where this interplay takes place. These concepts are illustrated by a variety of applications in amorphous solids, mesomorphic phases, and frustrated media in their curved habit space. These often involve disclination networks with specific node conditions. The powerful topological theory of line defects considers only defects stable against any change of boundary conditions or relaxation processes compatible with the structure considered. It can be seen as a simplified case of the approach considered here, particularly suited for media of high plasticity or/and complex structures. It cannot analyze the dynamical properties of defects nor the elastic constants involved in their static properties; topological stability cannot guarantee energetic stability, and sometimes cannot distinguish finer details of the structure of defects.

Innovation in user-centered skills and performance improvement for sustainable complex service systems.

Science.gov (United States)

Karwowski, Waldemar; Ahram, Tareq Z

2012-01-01

In order to leverage individual and organizational learning and to remain competitive in current turbulent markets it is important for employees, managers, planners and leaders to perform at high levels over time. Employee competence and skills are extremely important matters in view of the general shortage of talent and the mobility of employees with talent. Two factors emerged to have the greatest impact on the competitiveness of complex service systems: improving managerial and employee's knowledge attainment for skills, and improving the training and development of the workforce. This paper introduces the knowledge-based user-centered service design approach for sustainable skill and performance improvement in education, design and modeling of the next generation of complex service systems. The rest of the paper cover topics in human factors and sustainable business process modeling for the service industry, and illustrates the user-centered service system development cycle with the integration of systems engineering concepts in service systems. A roadmap for designing service systems of the future is discussed. The framework introduced in this paper is based on key user-centered design principles and systems engineering applications to support service competitiveness.

Observation and analysis of defect cluster production and interactions with dislocations

International Nuclear Information System (INIS)

Zinkle, S.J.; Matsukawa, Y.

2004-01-01

The current understanding of defect production fundamentals in neutron-irradiated face centered cubic (FCC) and body centered cubic (BCC) metals is briefly reviewed, based primarily on transmission electron microscope observations. Experimental procedures developed by Michio Kiritani and colleagues have been applied to quantify defect cluster size, density, and nature. Differences in defect accumulation behavior of irradiated BCC and FCC metals are discussed. Depending on the defect cluster obstacle strength, either the dispersed barrier hardening model or the Friedel-Kroupa-Hirsch weak barrier model can be used to describe major aspects of radiation hardening. Irradiation at low temperature can cause a change in deformation mode from dislocation cell formation at low doses to twinning or dislocation channeling at higher doses. The detailed interaction between dislocations and defect clusters helps determine the dominant deformation mode. Recent observations of the microstructure created by plastic deformation of quenched and irradiated metals are summarized, including in situ deformation results. Examples of annihilation of stacking fault tetrahedra by gliding dislocations and subsequent formation of mobile superjogs are shown

Infrared studies of defects formed during postirradiation anneals of Czochralski silicon

Science.gov (United States)

Londos, C. A.; Sarlis, N. V.; Fytros, L. G.

1998-10-01

This article reports on defect studies of neutron-irradiated Czochralski-grown silicon (Cz-Si) material by means of infrared spectroscopy. In particular, the investigation was focused on the evolution of the 828 cm-1 well-known band of A-center, due to isochronal anneals from room temperature (RT) up to ≈700 °C. The strength of the VO band begins to increase above ≈200 gradually up to 300 °C (stage I); then, it begins to decrease up to ≈400 °C (stage II), where upon it stabilizes up to ≈550 °C (stage III). Upon re-irradiation under exactly the same conditions and repeating the annealing process, the increase of the VO signal in stage I disappears. The phenomenon is ascribed to the existence of defect aggregates labeled as Xi centers which are correlated with (impurity-defect) clusters that compete with Oi in capturing vacancies. The presence of Xi centers is related to the thermal annealings performed. Comparison of the evolution of VO (828 cm-1) and VO2 (887 cm-1) bands between irradiated and re-irradiated materials, during stage II, is made and the results are discussed in the framework of established reaction patterns. The stabilization of the amplitude of the 828 cm-1 line in stage III is examined. The prevailing aspect is that a portion of A-centers in neutron-irradiated Si acquires larger thermal stability by relaxing in the vicinity of larger defects.

Calculations of the optical properties for FA1:Ag+ centers and CN interactions at the regular and defect sites of the LiI (0 0 1) surface: First principle calculations

International Nuclear Information System (INIS)

Abdel Aal, S.

2007-01-01

The optical properties of the F A1 :Ag + color centers and CN interactions at the flat, edge and corner surfaces of LiI (0 0 1) were investigated by using quantum mechanical configuration interaction singles (CIS) and density functional theory (DFT) ab initio methods. Clusters of variable sizes were embedded in the simulated Coulomb fields that closely approximate the Madelung fields of the host surfaces, and the nearest-neighbor ions to the defect site were allowed to relax to equilibrium in order to calculate the optical properties. The sensitivity of the calculated transition energies (Stokes shifts) of F A1 :Ag + centers as well as related optical properties such as optical-optical conversion efficiency, relaxed excited states of the defect-containing surface, orientational destruction of the point defect, recording sensitivity, and the Glasner-Tompkins empirical rule, to the coordination number of the surface ion and artificial polarization were examined. The dependance of the adsorption energies of CN at LiI (0 0 1) surface, the coadsorption of CN, and the charge transfer reactions between CN and the paramagnetic iodine vacancy on the coordination number and artificial polarization effects were also clarified

Study of defectiveness in orthosilicates of alkali earth metals by the method of radiospectroscopy

International Nuclear Information System (INIS)

Bikbau, M.Ya.; Akramov, R.

1978-01-01

With a view to investigating the defectiveness of the orthosilicates of alkali-earth metals, the spectra of the electronic paramagnetic resonance of γ-irradiated orthosilicates of Be, Mg, Ca, Sr and Ba have been examined. The spectra are obtained at 77 and 298 K. The maximum concentration and stability of paramagnetic centers is observed on the defects of the crystalline-optical structure of orthosilicates of Sr and Ba, as well as of β-Ca 2 SiO 4 . This is attributed to a great defectiveness of those compounds. On the basis of an analysis of the possible nature of electron and hole paramagnetic centers that are formed in the compounds examined by means of γ-irradiation, it has been suggested to form the electron centers of [M 2+ ]sub(n)sup(e) type. The formation of hole centers has been shown in aluminium used as addition

Defects in low temperature electron irradiated InP

International Nuclear Information System (INIS)

Suski, J.; Bourgoin, J.

1984-01-01

n and p-InP has been irradiated at 25K with 1MeV electrons and the created defects were studied by deep level transient spectroscopy (DLTS) in the range 25K-400K. In n-InP, four traps are directly observed, with low introduction rates except for one. They anneal in three stages, and four new centers of still lower concentration appear after 70 0 C heat treatment. In p-InP, two dominant traps stable up to approx.= 400K with introduction rates close to the theoretical ones, which might be primary defects are found, while another one is clearly a secondary defect likely associated to Zn dopant. At least two of the low concentration irradiation induced electron traps, created between 25K and 100K are also secondary defects, which implies a mobility of some primary defects down to 100K at least. (author)

Study of the irradiation defects in 3C-SiC

International Nuclear Information System (INIS)

Lefevre, J.

2007-01-01

This work deals with the study of the irradiation defects in the cubic polytype 3C of the n type silicon carbide. Low temperature photoluminescence and electron spin resonance techniques have been used. In situ photoluminescence measurements after irradiation at 10 K by electrons have shown that the nature of the defects induced is identical to those observed after irradiation at ambient temperature with electrons, protons or carbon ions. No regeneration of these defects has been revealed after in situ annealings until 300 K. The electrons Van de Graff accelerator of the Irradiated Solid Laboratory has allowed to irradiate sample of 3C in a range of energies between 190 keV and 1 MeV. It has then been possible to estimate the appearance threshold of the irradiation defects but especially to be able to determine the displacement threshold energy of silicon in this SiC polytype. The found value of 25 eV is in good agreement with the first experimental result proposed by X. Kerbiriou with the use of the ESR. Annealings in the range of high temperatures have been carried out. The evolution of the irradiation defects has been followed in photoluminescence and in ESR. The results show that, in one part, the vacancy of the silicon negatively charged is essentially the only compensating defect in 3C-SiC of n type and that, in another part, the majority of the defects are annealed below 1200 C. Only the D1 defect remains after annealings until 1600 C. The D1 center is in fact a native defect in SiC; indeed, it has been identified alone in non irradiated samples. A systematic study of these last samples show the absence of D1 in samples strongly compensated. The compared results of photoluminescence and of positons annihilation are in good agreement for the possible attribution of D1 to the bi-vacancy V C -V Si . One of the most interesting result of this last work has been obtained using the ESR technique under excitation with a neodymium laser. The measurements, carried

Genetics Home Reference: abdominal wall defect

Science.gov (United States)

... are two main types of abdominal wall defects: omphalocele and gastroschisis . Omphalocele is an opening in the center of the ... covering the exposed organs in gastroschisis. Fetuses with omphalocele may grow slowly before birth (intrauterine growth retardation) ...

Quantum computing with defects in diamond

International Nuclear Information System (INIS)

Jelezko, F.; Gaebel, T.; Popa, I.; Domhan, M.; Wittmann, C.; Wrachtrup, J.

2005-01-01

Full text: Single spins in semiconductors, in particular associated with defect centers, are promising candidates for practical and scalable implementation of quantum computing even at room temperature. Such an implementation may also use the reliable and well known gate constructions from bulk nuclear magnetic resonance (NMR) quantum computing. Progress in development of quantum processor based on defects in diamond will be discussed. By combining optical microscopy, and magnetic resonance techniques, the first quantum logical operations on single spins in a solid are now demonstrated. The system is perspective for room temperature operation because of a weak dependence of decoherence on temperature (author)

Human diseases associated with defective DNA repair

International Nuclear Information System (INIS)

Friedberg, E.C.; Ehmann, U.K.; Williams, J.I.

1979-01-01

The observations on xeroderma pigmentosum (XP) cells in culture were the first indications of defective DNA repair in association with human disease. Since then, a wealth of information on DNA repair in XP, and to a lesser extent in other diseases, has accumulated in the literature. Rather than clarifying the understanding of DNA repair mechanisms in normal cells and of defective DNA repair in human disease, the literature suggests an extraordinary complexity of both of the phenomena. In this review a number of discrete human diseases are considered separately. An attempt was made to systematically describe the pertinent clinical features and cellular and biochemical defects in these diseases, with an emphasis on defects in DNA metabolism, particularly DNA repair. Wherever possible observations have been correlated and unifying hypotheses presented concerning the nature of the basic defect(s) in these diseases. Discussions of the following diseases are presented: XP, ataxia telangiectasia; Fanconi's anemia; Hutchinson-Gilford progeria syndrome; Bloom's syndrome, Cockayne's syndrome; Down's syndrome; retinoblastoma; chronic lymphocytic leukemia; and other miscellaneous human diseases with possble DNA repair defects

Varying stiffness and load distributions in defective ball bearings: Analytical formulation and application to defect size estimation

Science.gov (United States)

Petersen, Dick; Howard, Carl; Prime, Zebb

2015-02-01

This paper presents an analytical formulation of the load distribution and varying effective stiffness of a ball bearing assembly with a raceway defect of varying size, subjected to static loading in the radial, axial and rotational degrees of freedom. The analytical formulation is used to study the effect of the size of the defect on the load distribution and varying stiffness of the bearing assembly. The study considers a square-shaped outer raceway defect centered in the load zone and the bearing is loaded in the radial and axial directions while the moment loads are zero. Analysis of the load distributions shows that as the defect size increases, defect-free raceway sections are subjected to increased static loading when one or more balls completely or partly destress when positioned in the defect zone. The stiffness variations that occur when balls pass through the defect zone are significantly larger and change more rapidly at the defect entrance and exit than the stiffness variations that occur for the defect-free bearing case. These larger, more rapid stiffness variations generate parametric excitations which produce the low frequency defect entrance and exit events typically observed in the vibration response of a bearing with a square-shaped raceway defect. Analysis of the stiffness variations further shows that as the defect size increases, the mean radial stiffness decreases in the loaded radial and axial directions and increases in the unloaded radial direction. The effects of such stiffness changes on the low frequency entrance and exit events in the vibration response are simulated with a multi-body nonlinear dynamic model. Previous work used the time difference between the low frequency entrance event and the high frequency exit event to estimate the size of the defect. However, these previous defect size estimation techniques cannot distinguish between defects that differ in size by an integer number of the ball angular spacing, and a third feature

Repairing Nanoparticle Surface Defects

NARCIS (Netherlands)

Marino, Emanuele; Kodger, Thomas E.; Crisp, R.W.; Timmerman, Dolf; MacArthur, Katherine E.; Heggen, Marc; Schall, Peter

2017-01-01

Solar devices based on semiconductor nanoparticles require the use of conductive ligands; however, replacing the native, insulating ligands with conductive metal chalcogenide complexes introduces structural defects within the crystalline nanostructure that act as traps for charge carriers. We

Electronic structure of point defects in semiconductors

International Nuclear Information System (INIS)

Bruneval, Fabien

2014-01-01

This 'Habilitation a diriger des Recherches' memoir presents most of my scientific activities during the past 7 years, in the field of electronic structure calculations of defects in solids. Point defects (vacancies, interstitials, impurities) in functional materials are a key parameter to determine if these materials will actually fill the role they have been assigned or not. Indeed, the presence of defects cannot be avoided when the temperature is increased or when the material is subjected to external stresses, such as irradiation in the nuclear reactors and in artificial satellites with solar radiations. However, in many cases, defects are introduced in the materials on purpose to tune the electronic transport, optical or even magnetic properties. This procedure is called the doping of semiconductors, which is the foundation technique for transistors, diodes, or photovoltaic cells. However, doping is not always straightforward and unexpected features may occur, such as doping asymmetry or Fermi level pinning, which can only be explained by complex phenomena involving different types of defects or complexes of defects. In this context, the calculations of electronic structure ab initio is an ideal tool to complement the experimental observations, to gain the understanding of phenomena at the atomic level, and even to predict the properties of defects. The power of the ab initio calculations comes from their ability to describe any system of electrons and nuclei without any specific adjustment. But although there is a strong need for numerical simulations in this field, the ab initio calculations for defects are still under development as of today. The work presented in this memoir summarizes my contributions to methodological developments on this subject. These developments have followed two main tracks. The first topic is the better understanding of the unavoidable finite size effects. Indeed, defects in semiconductors or insulators are generally present in

Experimental study of defect power reactor fuel. Final report

International Nuclear Information System (INIS)

Forsyth, R.S.; Jonsson, T.

1982-01-01

Two BWR fuel rods, one intact and one defect, with the same manufacturing and irradiation data have been examined in a comparative study. The defect rod has been irradiated in a defect condition during approximately one reactor cycle and has consequently some secondary defects. The defect rod has two penetrating defects at a distance of about 1.5 meters from each other. Comparison with the intact rod shows a large Cs loss from the defect rod, especially between the cladding defects, where the loss is measured to about 30 %. The leachibility in deionized water is higher for Cs, U and Cm for fuel from the defect rod. The leaching results are more complex for Sr-90, Pu and Am. The fuel in the defect rod has undergone a change of structure with gain growth and formation of oriented fuel structure. The cladding of the defect rod is hydrided locally in some parts of the lower part of the rod and furthermore over a more extended region near the end of the rod. (Authors)

Menaquinone-7 in the reaction center complex of the green sulfur bacterium Chlorobium vibrioforme functions as the electron acceptor A1

DEFF Research Database (Denmark)

Kjaer, B; Frigaard, N-U; Yang, F

1998-01-01

Photosynthetically active reaction center complexes were prepared from the green sulfur bacterium Chlorobium vibrioforme NCIMB 8327, and the content of quinones was determined by extraction and high-performance liquid chromatography. The analysis showed a stoichiometry of 1.7 molecules of menaqui......Photosynthetically active reaction center complexes were prepared from the green sulfur bacterium Chlorobium vibrioforme NCIMB 8327, and the content of quinones was determined by extraction and high-performance liquid chromatography. The analysis showed a stoichiometry of 1.7 molecules...

A quantum-chemical study of oxygen-vacancy defects in PbTiO{sub 3} crystals

Energy Technology Data Exchange (ETDEWEB)

Stashans, Arvids [Laboratorio de Fisica, Escuela de Electronica y Telecomunicaciones, Universidad Tecnica Particular de Loja, Apartado 11-01-608, Loja (Ecuador)]. E-mail: arvids@utpl.edu.ec; Serrano, Sheyla [Centro de Investigacion en Fisica de Materia Condensada, Corporacion de Fisica Fundamental y Aplicada, Apartado 17-12-637, Quito (Ecuador); Escuela de Ingenierias, Universidad Politecnica Salesiana, Campus Sur, Rumichaca s/n y Moran Valverde, Apartado 17-12-536, Quito (Ecuador); Medina, Paul [Centro de Investigacion en Fisica de Materia Condensada, Corporacion de Fisica Fundamental y Aplicada, Apartado 17-12-637, Quito (Ecuador)

2006-05-31

Investigation of an oxygen vacancy and F center in the cubic and tetragonal lattices of PbTiO{sub 3} crystals is done by means of quantum-chemical simulations. Displacements of defect-surrounding atoms, electronic and optical properties, lattice relaxation energies and some new effects due to the defects presence are reported and analyzed. A comparison with similar studies is made and conclusions are drawn on the basis of the obtained results.

Cathodoluminescence investigation of Ge-point defects in silica-based optical fibers

Energy Technology Data Exchange (ETDEWEB)

Reghioua, I., E-mail: imene.reghioua@univ-st-etienne.fr [Univ-Lyon, Laboratoire H. Curien, UMR CNRS 5516, 18 rue du Pr. Benoît Lauras, 42000 Saint-Etienne (France); Girard, S.; Alessi, A.; Di Francesca, D. [Univ-Lyon, Laboratoire H. Curien, UMR CNRS 5516, 18 rue du Pr. Benoît Lauras, 42000 Saint-Etienne (France); Martin-Samos, L.; Fanetti, M. [Materials Research Laboratory, University of Nova Gorica, Vipavska 11c 5270-Ajdovscina (Slovenia); Richard, N.; Raine, M. [CEA, DAM, DIF, F91297, Arpajon (France); Valant, M. [Materials Research Laboratory, University of Nova Gorica, Vipavska 11c 5270-Ajdovscina (Slovenia); Boukenter, A.; Ouerdane, Y. [Univ-Lyon, Laboratoire H. Curien, UMR CNRS 5516, 18 rue du Pr. Benoît Lauras, 42000 Saint-Etienne (France)

2016-11-15

Cathodoluminescence (CL) measurements have been performed on Ge doped and Ge/F co-doped optical fibers, in the aim of studying the spatial distributions of the emitting precursor defects present in the as-drawn optical fiber as well as those of the radiation induced centers generated by the 10 keV electron exposure. Using the CL instrument, we recorded different emission bands located in the visible spectral domain (300–750 nm) as well as CL imaging of associated defects, with a spatial resolution of about 1 µm, along the fiber transverse cross sections. In the pristine fiber, Germanium Lone Pair Centers (GLPCs) emitting at 400 nm are the main precursor sites observed in both fibers. Whereas during electron exposure, these centers are converted into other Ge-related defects. In this paper, we studied in situ their bleaching kinetic using CL monochromatic imaging. As expected, our results show that the GLPC signal decreases with the electron fluence, confirming its precursor role. Thanks to the CL abilities, we also demonstrate that the GLPC conversion into radiation induced defects (and then its bleaching kinetic) depends on the germanium concentration, opening the way to a better control of the radiation sensitivity of germanosilicate glass.

Characterization of point defects in CdTe by positron annihilation spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Elsharkawy, M. R. M. [Carnegie Laboratory of Physics, SUPA, School of Science and Engineering, University of Dundee, Dundee DD1 4HN (United Kingdom); Physics Department, Faculty of Science, Minia University, P.O. Box 61519, Minia (Egypt); Kanda, G. S.; Keeble, D. J., E-mail: d.j.keeble@dundee.ac.uk [Carnegie Laboratory of Physics, SUPA, School of Science and Engineering, University of Dundee, Dundee DD1 4HN (United Kingdom); Abdel-Hady, E. E. [Physics Department, Faculty of Science, Minia University, P.O. Box 61519, Minia (Egypt)

2016-06-13

Positron lifetime measurements on CdTe 0.15% Zn-doped by weight are presented, trapping to monovacancy defects is observed. At low temperatures, localization at shallow binding energy positron traps dominates. To aid defect identification density functional theory, calculated positron lifetimes and momentum distributions are obtained using relaxed geometry configurations of the monovacancy defects and the Te antisite. These calculations provide evidence that combined positron lifetime and coincidence Doppler spectroscopy measurements have the capability to identify neutral or negative charge states of the monovacancies, the Te antisite, A-centers, and divacancy defects in CdTe.

How the Center for Public Partnerships and Research Navigates Complex Social Problems to Make a Collective Difference.

Science.gov (United States)

Counts, Jacqueline; Gillam, Rebecca; Garstka, Teri A; Urbach, Ember

2018-01-01

The challenge of maximizing the well-being of children, youth, and families is recognizing that change occurs within complex social systems. Organizations dedicated to improving practice, advancing knowledge, and informing policy for the betterment of all must have the right approach, structure, and personnel to work in these complex systems. The University of Kansas Center for Public Partnerships and Research cultivates a portfolio of innovation, research, and data science approaches positioned to help move social service fields locally, regionally, and nationally. Mission, leadership, and smart growth guide our work and drive our will to affect positive change in the world.

Complex defects in the oxidation of uranium

International Nuclear Information System (INIS)

MacCrone, R.K.; Sankaran, S.; Shatynski, S.R.; Colmenares, C.A.

1986-01-01

We are reporting EPR results obtained with uranium powder samples fully oxidized in dry air, water vapor, and air/water vapor mixtures. The results reported previously are confirmed and additional paramagnetic centers, associated with chemisorbed species, have been identified. The temperature dependence of the g-value for these centers from room temperature to 10K is also reported

Laser-induced positive ion and neutral atom/molecule emissions from single-crystal CaHPO4 center dot 2H20: The role of electron-beam-induced defects

International Nuclear Information System (INIS)

Dawes, Mary L.; Hess, Wayne P.; Kawaguchi, Yuji; Langford, S C.; Dickinson, J. Tom

1998-01-01

We examine laser-induced ion and neutral emissions from single-crystal CaHPO4 center dot 2H2O (brushite), a wide-band-gap, hydrated inorganic single crystal, with 248-nm excimer laser radiation. Both laser-induced ion and neutral emissions are several orders magnitude higher following exposure to 2keV electrons at current densities of 200 uA/cm2 and doses of 1 C/cm2. In addition to intense Ca+ signals, electron-irradiated surfaces yield substantial CaO+, PO+, and P+ signals. As-grown and as-cleaved brushite show only weak neutral O2 and Ca emissions, whereas electron-irradiated surfaces yield enhanced O2, Ca, PO, PO2, and P emissions. Electron irradiation (i) significantly heats the sample, leading to thermal dehydration (CaHPO4 formation) and pyrolysis (Ca2P2O7 formation)and (ii) chemically reduces the surface via electron stimulated desorption. The thermal effects are accompanied by morphological changes, including recrystallization. Although complex, these changes lead to high defect densities, which are responsible for the dramatic enhancements in the observed laser desorption

Use of customized polyetheretherketone (PEEK) implants in the reconstruction of complex maxillofacial defects.

Science.gov (United States)

Kim, Michael M; Boahene, Kofi D O; Byrne, Patrick J

2009-01-01

Extensive maxillofacial defects resulting from trauma or oncologic resection present reconstructive challenges. Various autografts and alloplastic materials in conjunction with standard soft-tissue techniques have been used in the reconstruction of these types of defects. Polyetheretherketone (PEEK) is a semicrystalline polyaromatic linear polymer exhibiting an excellent combination of strength, stiffness, durability, and environmental resistance. Recent investigations of PEEK as a biomaterial resulted in the successful treatment of cervical disk disease. We describe a series of 4 patients whose defects were reconstructed using customized PEEK implants. All had excellent postoperative aesthetic and functional results without complications such as infections or extrusions. Because PEEK implants are customizable, easily workable, inert, and nonporous, they represent an ideal alloplastic material for maxillofacial reconstruction.

Ultrasonographic diagnosis of limb-body wall complex: a case report

Energy Technology Data Exchange (ETDEWEB)

Goo, Dong Erk; Yoo, Shi Joon; Cho, Kyoung Sik; Choi, Kee Young; Kim, Am [University of Ulsan College of Medicine, Asan Medical Center, Ulsan (Korea, Republic of)

1993-12-15

Limb-body wall complex (LBWC) is a rare congenital process believed to result from early rupture of the amnion, possibly as a consequence of vascular disruption. Characteristic fetal deformities include limb defects, scoliosis, thoracoschisis and/or abdominoschisis, and severe craniofacial anomalies. This complex should be distinguished from other body-wall defect including omphalocele and gastroschisis since the prognosis of LBWC is uniformly poor. We report a case of LBWC which was diagnosed by prenatal ultrasonography in 26 weeks of gestation. Prenatal ultrasonograms are correlated with the gross pathologic findings. The present case demonstrates the superb capability of modern ultrasonography in the diagnosis of complex fetal anomalies

Ultrasonographic diagnosis of limb-body wall complex: a case report

International Nuclear Information System (INIS)

Goo, Dong Erk; Yoo, Shi Joon; Cho, Kyoung Sik; Choi, Kee Young; Kim, Am

1993-01-01

Limb-body wall complex (LBWC) is a rare congenital process believed to result from early rupture of the amnion, possibly as a consequence of vascular disruption. Characteristic fetal deformities include limb defects, scoliosis, thoracoschisis and/or abdominoschisis, and severe craniofacial anomalies. This complex should be distinguished from other body-wall defect including omphalocele and gastroschisis since the prognosis of LBWC is uniformly poor. We report a case of LBWC which was diagnosed by prenatal ultrasonography in 26 weeks of gestation. Prenatal ultrasonograms are correlated with the gross pathologic findings. The present case demonstrates the superb capability of modern ultrasonography in the diagnosis of complex fetal anomalies

Deep-level defects in semiconductors: studies by magnetic resonance

International Nuclear Information System (INIS)

Ammerlaan, C.A.J.

1983-01-01

This work is divided into two parts. In the first one, the following topics are discussed: paramagnetic centers in semiconductors, principles of magnetic resonance, spin-Hamiltonian, g-tensor, hyperfine interaction, magnetic resonance spectrometer. In the second part it is dicussed defects studied by magnetic resonance including vacancy and divacancy in silicon, iron in silicon, nitrogen in diamond and antisite defects in III-V compounds. (A.C.A.S.) [pt

A study of the electrical properties of defects in silicon

International Nuclear Information System (INIS)

Blood, A.M.

1998-01-01

This work contains the most comprehensive qualitative and quantitative electron beam induced current (EBIC) study of recombination at contaminated defects in silicon. It is also a rigorous quantitative investigation of the effect of hydrogen on individual transition metal contaminated defects. In addition, the recombination behaviour exhibited by point and extended defects has been investigated using EBIC and deep level transient spectroscopy (DLTS). As a result of these measurements, techniques for the preparation of transition metal contaminated specimens have been refined. Successful hydrogen passivation of copper, nickel and iron contaminated silicon specimens containing oxidation-induced stacking faults has been achieved in two experimental systems. It is found that hydrogen passivates those states that are deepest in the semiconductor band gap in preference to those that are shallow. Furthermore, it has been concluded that during hydrogen passivation treatment, even at low temperatures, unwanted metallic impurities can be introduced. Three types of recombination behaviour have been identified from the defects-studied in this work and they are discussed with relevance to present recombination models. An investigation of the recombination behaviour of defects that lie in the depletion region and in the specimen bulk has concluded that the recombination type observed is independent of the depth of the defect. Evidence for the presence of compound defects showing mixed recombination behaviour type is presented. In conclusion, it is postulated that the transition metal impurities introduce a 'band of states' with a range of energies rather than a single energy state. This proposal is provided as an explanation for the recombination types found in this work and the effect of the hydrogen passivation. This work is placed in context of previous investigations into the behaviour of dislocations in silicon in the presence of transition metals, and the ability of

Defect phase diagram for doping of Ga2O3

OpenAIRE

Stephan Lany

2018-01-01

For the case of n-type doping of β-Ga2O3 by group 14 dopants (C, Si, Ge, Sn), a defect phase diagram is constructed from defect equilibria calculated over a range of temperatures (T), O partial pressures (pO2), and dopant concentrations. The underlying defect levels and formation energies are determined from first-principles supercell calculations with GW bandgap corrections. Only Si is found to be a truly shallow donor, C is a deep DX-like (lattice relaxed donor) center, and Ge and Sn have d...

Detection of oxygen-related defects in GaAs by exo-electron emission spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Hulluvarad, Shiva S.; Naddaf, M.; Bhoraskar, S.V. E-mail: svb@physics.unipune.ernet.in

2001-10-01

The influence of intentional introduction of oxygen, at the surface of GaAs, on its native surface states was studied. Oxygen was made to interact with the surface of GaAs by three different means: (1) by growing native oxides, (2) exposing to oxygen plasma in an electron cyclotron resonance (ECR) plasma reactor and by (3) high energy oxygen ion irradiation. Thermally stimulated exo-electron emission (TSEE) spectroscopy was used to estimate the relative densities and energies of the surface states induced by the three different modes of introducing oxygen. Out of the two native defect levels found in GaAs by TSEE; at 325 K (0.7 eV below E{sub c}) and at 415 K (0.9 below E{sub c}); the former is seen to get broadened or split into multiple peaks in each of the methods. Multiple peaks in TSEE signify the presence of a closely spaced band of defect levels. Therefore the results exclusively point out that oxygen-related complexes contribute to the formation of a band of defects centered at 325 K in TSEE which is correlated to an energy level 0.7 eV below E{sub c} known as the EL2 defect level. The results reported in this paper thus confirm that the TSEE peak at 0.7 eV below E{sub c} is related to oxygen induced defects whereas the peak at 0.9 eV is not affected by the presence of oxygen-related species.

Defects in tor regulatory complexes retard aging and carbonyl/oxidative stress development in yeast Sассharomyces cerevisiae

Directory of Open Access Journals (Sweden)

B. V. Homza

2014-02-01

Full Text Available TOR signaling pathway first described in yeast S. сerevisiae is the highly conserved regulator of eukaryotic cell growth, aging and stress resistance. The effect of nitrogen sources, in particular amino acids, on the activity of TOR signaling pathway is well studied, however its relation to carbohydrates is poor understood. The aim of the present study is expanding of our understanding of potential role of TOR regulatory complexes in development of carbonyl/oxidative stress that can result from yeast cultivation on glucose and fructose. It has been shown that the level of α-dicarbonyl compounds and protein carbonyl groups increased with time of yeast cultivation and was higher in cells grown on fructose that demonstrated their accelerated aging and carbonyl/oxidative stress development as compared with cells grown on glucose. The strains defective in TOR proteins cultivated in the presence of glucose as well as fructose demonstrated lower markers of the stress and aging than parental strain. Thus these data confirmed the previous conclusion on fructose more potent ability to cause carbonyl/oxidative stress and accelerated aging in S. cerevisiae as compared with glucose. However, defects in TOR regulatory complexes retard aging and development of the stress in yeast independent on the type of carbohydrate in the cultivation medium.

Deep level centers in electron-irradiated silicon crystals doped with copper at different temperatures

Energy Technology Data Exchange (ETDEWEB)

Yarykin, Nikolai [Institute of Microelectronics Technology, RAS, Chernogolovka (Russian Federation); Weber, Joerg [Technische Universitaet Dresden (Germany)

2017-07-15

The effect of bombardment with energetic particles on the deep-level spectrum of copper-contaminated silicon wafers is studied by space charge spectroscopy methods. The p-type FZ-Si wafers were doped with copper in the temperature range of 645-750 C and then irradiated with the 10{sup 15} cm{sup -2} fluence of 5 MeV electrons at room temperature. Only the mobile Cu{sub i} species and the Cu{sub PL} centers are detected in significant concentrations in the non-irradiated Cu-doped wafers. The properties of the irradiated samples are found to qualitatively depend on the copper in-diffusion temperature T{sub diff}. For T{sub diff} > 700 C, the irradiation partially reduces the Cu{sub i} concentration and introduces additional Cu{sub PL} centers while no standard radiation defects are detected. If T{sub diff} was below ∝700 C, the irradiation totally removes the mobile Cu{sub i} species. Instead, the standard radiation defects and their complexes with copper appear in the deep-level spectrum. A model for the defects reaction scheme during the irradiation is derived and discussed. DLTS spectrum of the Cu-contaminated and then irradiated silicon qualitatively depends on the copper in-diffusion temperature. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Origin of dislocation luminescence centers and their reorganization in p-type silicon crystal subjected to plastic deformation and high temperature annealing.

Science.gov (United States)

Pavlyk, Bohdan; Kushlyk, Markiyan; Slobodzyan, Dmytro

2017-12-01

Changes of the defect structure of silicon p-type crystal surface layer under the influence of plastic deformation and high temperature annealing in oxygen atmosphere were investigated by deep-level capacitance-modulation spectroscopy (DLCMS) and IR spectroscopy of molecules and atom vibrational levels. Special role of dislocations in the surface layer of silicon during the formation of its energy spectrum and rebuilding the defective structure was established. It is shown that the concentration of linear defects (N ≥ 10 4  cm -2 ) enriches surface layer with electrically active complexes (dislocation-oxygen, dislocation-vacancy, and dislocation-interstitial atoms of silicon) which are an effective radiative recombination centers.

Classification of maxillectomy defects: a systematic review and criteria necessary for a universal description.

Science.gov (United States)

Bidra, Avinash S; Jacob, Rhonda F; Taylor, Thomas D

2012-04-01

Maxillectomy defects are complex and involve a number of anatomic structures. Several maxillectomy defect classifications have been proposed with no universal acceptance among surgeons and prosthodontists. Established criteria for describing the maxillectomy defect are lacking. This systematic review aimed to evaluate classification systems in the available literature, to provide a critical appraisal, and to identify the criteria necessary for a universal description of maxillectomy and midfacial defects. An electronic search of the English language literature between the periods of 1974 and June 2011 was performed by using PubMed, Scopus, and Cochrane databases with predetermined inclusion criteria. Key terms included in the search were maxillectomy classification, maxillary resection classification, maxillary removal classification, maxillary reconstruction classification, midfacial defect classification, and midfacial reconstruction classification. This was supplemented by a manual search of selected journals. After application of predetermined exclusion criteria, the final list of articles was reviewed in-depth to provide a critical appraisal and identify criteria for a universal description of a maxillectomy defect. The electronic database search yielded 261 titles. Systematic application of inclusion and exclusion criteria resulted in identification of 14 maxillectomy and midfacial defect classification systems. From these articles, 6 different criteria were identified as necessary for a universal description of a maxillectomy defect. Multiple deficiencies were noted in each classification system. Though most articles described the superior-inferior extent of the defect, only a small number of articles described the anterior-posterior and medial-lateral extent of the defect. Few articles listed dental status and soft palate involvement when describing maxillectomy defects. No classification system has accurately described the maxillectomy defect, based on

Bipolar Alq3-based complexes: Effect of hole-transporting substituent on the properties of Alq3-center

International Nuclear Information System (INIS)

Luo Jianxin; Lu Mangeng; Yang Chaolong; Tong Bihai; Liang Liyan

2012-01-01

Two bipolar Alq 3 -based complexes, tris{5-[(carbazole-9'-yl)methyl]-8-hydroxyquinoline} aluminum (Al(CzHQ) 3 ) and tris{5-[(phenothiazine-9'-yl)methyl]-8-hydroxyquinoline} aluminum (Al(PHQ) 3 ), involving an Alq 3 -center and three hole-transporting substituents (carbazole or phenothiazine), were prepared and characterized. Effects of hole-transporting substituent on the properties of Alq 3 -center were investigated in detail. It is found that the two complexes have improved hole-transporting performance and appropriate thermal stability (the 5%-weight-loss temperatures T 5% >260 °C). Photoluminescence (PL) spectra indicate that both energy transfer and electron transfer can take place simultaneously in the PL process of these complexes. Both thermodynamics and dynamics of the electron transfer were studied and corresponding parameters were calculated. Energy transfer is favorable for the PL of Alq 3 -center, while electron transfer is unfavorable for the PL of Alq 3 -center. These results will be useful to explore novel OLEDs material with increased efficiency. - Highlights: ► Effects of substituent on the properties of Alq 3 -center were investigated. ► Energy transfer and electron transfer can transfer from substituent to Alq 3 -center. ► The thermodynamics and dynamics of electron transfer were studied. ► The mechanisms of PL and EL of Al(CzHQ) 3 were studied and compared with each other.

Limb body wall complex: A rare anomaly

Directory of Open Access Journals (Sweden)

Panduranga Chikkannaiah

2013-01-01

Full Text Available We present autopsy findings of a case of limb body wall complex (LBWC. The fetus had encephalocele, genitourinary agenesis, skeletal anomalies and body wall defects. The rare finding in our case is the occurrence of both cranial and urogenital anomalies. The presence of complex anomalies in this fetus, supports embryonal dysplasia theory of pathogenesis for LBWC.

Universe as a topological defect

International Nuclear Information System (INIS)

Anabalon, Andres; Willison, Steven; Zanelli, Jorge

2008-01-01

Four-dimensional Einstein's general relativity is shown to arise from a gauge theory for the conformal group, SO(4,2). The theory is constructed from a topological dimensional reduction of the six-dimensional Euler density integrated over a manifold with a four-dimensional topological defect. The resulting action is a four-dimensional theory defined by a gauged Wess-Zumino-Witten term. An ansatz is found which reduces the full set of field equations to those of Einstein's general relativity. When the same ansatz is replaced in the action, the gauged WZW term reduces to the Einstein-Hilbert action. Furthermore, the unique coupling constant in the action can be shown to take integer values if the fields are allowed to be analytically continued to complex values

Thyroid Medication Use and Birth Defects in the National Birth Defects Prevention Study.

Science.gov (United States)

Howley, Meredith M; Fisher, Sarah C; Van Zutphen, Alissa R; Waller, Dorothy K; Carmichael, Suzan L; Browne, Marilyn L

2017-11-01

Thyroid disorders are common among reproductive-aged women, with hypothyroidism affecting 2 to 3% of pregnancies, and hyperthyroidism affecting an additional 0.1 to 1%. We examined associations between thyroid medications and individual birth defects using data from the National Birth Defects Prevention Study (NBDPS). The NBDPS is a multisite, population-based, case-control study that included pregnancies with estimated delivery dates from 1997 to 2011. We analyzed self-reported thyroid medication use from mothers of 31,409 birth defect cases and 11,536 unaffected controls. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using logistic regression for birth defects with five or more exposed cases, controlling for maternal age, race/ethnicity, and study center. Crude ORs and exact 95% CIs were estimated for defects with 3 to 4 exposed cases. Thyroid hormone was used by 738 (2.3%) case and 237 (2.1%) control mothers, and was associated with anencephaly (OR = 1.68; 95% CI, 1.03-2.73), holoprosencephaly (OR = 2.48; 95% CI, 1.13-5.44), hydrocephaly (1.77; 95% CI, 1.07-2.95) and small intestinal atresia (OR = 1.81; 95% CI, 1.04-3.15). Anti-thyroid medication was used by 34 (0.1%) case and 10 (<0.1%) control mothers, and was associated with aortic valve stenosis (OR = 6.91; 95% CI, 1.21-27.0). While new associations were identified, our findings are relatively consistent with previous NBDPS analyses. Our findings suggest thyroid medication use is not associated with most birth defects studied in the NBDPS, but may be associated with some specific birth defects. These results should not be interpreted to suggest that medications used to treat thyroid disease are teratogens, as the observed associations may reflect effects of the underlying thyroid disease. Birth Defects Research 109:1471-1481, 2017.© 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Deterministic Electrical Charge-State Initialization of Single Nitrogen-Vacancy Center in Diamond

Directory of Open Access Journals (Sweden)

Y. Doi

2014-03-01

Full Text Available Apart from applications in classical information-processing devices, the electrical control of atomic defects in solids at room temperature will have a tremendous impact on quantum devices that are based on such defects. In this study, we demonstrate the electrical manipulation of individual prominent representatives of such atomic solid-state defects, namely, the negative charge state of single nitrogen-vacancy defect centers (NV^{−} in diamond. We experimentally demonstrate, deterministic, purely electrical charge-state initialization of individual NV centers. The NV centers are placed in the intrinsic region of a p-i-n diode structure that facilitates the delivery of charge carriers to the defect for charge-state switching. The charge-state dynamics of a single NV center were investigated by time-resolved measurements and a nondestructive single-shot readout of the charge state. Fast charge-state switching rates (from negative to neutrally charged defects, which are greater than 0.72 ± 0.10  μs^{−1}, were realized. Furthermore, in no-operation mode, the realized charge states were stable for presumably much more than 0.45 s. We believe that the results obtained are useful not only for ultrafast electrical control of qubits, long T_{2} quantum memory, and quantum sensors associated with single NV centers but also for classical memory devices based on single atomic storage bits working under ambient conditions.

On Complex Nuclei Energetics in LENR

Science.gov (United States)

Miley, George H.; Hora, Heinz

2005-03-01

Swimming Electron Layer (SEL) theory plus fission of ``complex nuclei'' were proposed earlier to explain reaction products observed in electrolysis with multi-layer thin-film metallic electrodesootnotetext1.G.H. Miley, and J.A. Patterson, J. New Energy, Vol. 1, pp.11-15, (1996).. SEL was then extended to treat gas-diffusion driven transmutation experimentsootnotetextG. H. Miley and H. Hora, ``Nuclear Reactions in Solids,'' APS DNP Mtg., East Lansing, MI, Oct (2002).. It is also consistent with measured charged-particle emission during thin-film electrolysis and x-ray emission during plasma bombardment experimentsootnotetextA. Karabut, ``X-ray emission in high-current glow discharge,'' Proc., ICCF-9, Beijing China, May (2002).. The binding energy per complex nucleon can be estimated by an energy balance combined with identification of products for each complex e.g. complexes of A 39 have ˜ 0.05 MeV/Nucleon, etc, in thin film electrolysis. Energies in gas diffusion experiments are lower due to the reduced trap site potential at the multi-atom surface. In the case of x-ray emission, complexes involve subsurface defect center traps, giving only a few keV/Nucleon, consistent with experiments^3.

Radiation effects and defects in lithium borate crystals

Science.gov (United States)

Ogorodnikov, Igor N.; Poryvay, Nikita E.; Pustovarov, Vladimir A.

2010-11-01

The paper presents the results of a study of the formation and decay of lattice defects in wide band-gap optical crystals of LiB3O5 (LBO), Li2B4O7 (LTB) and Li6Gd(BO3)3 (LGBO) with a sublattice of mobile lithium cations. By means of thermoluminescence techniques, and luminescent and absorption optical spectroscopy with a nanosecond time resolution under excitation with an electron beam, it was revealed that the optical absorption in these crystals in the visible and ultraviolet spectral ranges is produced by optical hole-transitions from the local defect level to the valence band states. The valence band density of the states determines mainly the optical absorption spectral profile, and the relaxation kinetics is rated by the interdefect non-radiative tunnel recombination between the trapped-hole center and the Li0 trapped-electron centers. At 290 K, the Li0 centers are subject to thermally stimulated migration. Based on experimental results, the overall picture of thermally stimulated recombination processes with the participation of shallow traps was established for these crystals.

Spectral dependence of point defect production by x rays in RbBr

International Nuclear Information System (INIS)

Brown, F.C.; Heald, S.M.; Jiang, D.; Brewe, D.L.; Kim, K.H.; Stern, E.A.

1999-01-01

F-center formation by monochromatic x rays has been studied above and below the bromine and rubidium K-absorption edges in crystals of RbBr. The x-ray beam from a double silicon crystal monochromator on an undulator at the Advanced Photon Source was used to produce these point defects, which were detected by a sensitive laser-induced luminescence method. Experiments were carried out over a wide range of monochromatic x-ray intensity, with emphasis on the nearly linear initial slope of defect formation with exposure. No significant increase in F-center formation efficiency was found upon crossing the bromine K edge, which indicates that additional Auger-cascade mechanisms do not appreciably add to the usual multiple ionization electron-hole recombination processes known to generate point defects. copyright 1999 The American Physical Society

Phosphorescent heterobimetallic complexes involving platinum(iv) and rhenium(vii) centers connected by an unsupported μ-oxido bridge.

Science.gov (United States)

Molaee, Hajar; Nabavizadeh, S Masoud; Jamshidi, Mahboubeh; Vilsmeier, Max; Pfitzner, Arno; Samandar Sangari, Mozhgan

2017-11-28

Heterobimetallic compounds [(C^N)LMe 2 Pt(μ-O)ReO 3 ] (C^N = ppy, L = PPh 3 , 2a; C^N = ppy, L = PMePh 2 , 2b; C^N = bhq, L = PPh 3 , 2c; C^N = bhq, L = PMePh 2 , 2d) containing a discrete unsupported Pt(iv)-O-Re(vii) bridge have been synthesized through a targeted synthesis route. The compounds have been prepared by a single-pot synthesis in which the Pt(iv) precursor [PtMe 2 I(C^N)L] complexes are allowed to react easily with AgReO 4 in which the iodide ligand of the starting Pt(iv) complex is replaced by an ReO 4 - anion. In these Pt-O-Re complexes, the Pt(iv) centers have an octahedral geometry, completed by a cyclometalated bidentate ligand (C^N), two methyl groups and a phosphine ligand, while the Re(vii) centers have a tetrahedral geometry. Elemental analysis, single crystal X-ray diffraction analysis and multinuclear NMR spectroscopy are used to establish their identities. The new complexes exhibit phosphorescence emission in the solid and solution states at 298 and 77 K, which is an uncommon property of platinum complexes with an oxidation state of +4. According to DFT calculations, we found that this emission behavior in the new complexes originates from ligand centered 3 LC (C^N) character with a slight amount of metal to ligand charge transfer ( 3 MLCT). The solid-state emission data of the corresponding cycloplatinated(iv) precursor complexes [PtMe 2 I(C^N)L], 1a-1d, pointed out that the replacement of I - by an ReO 4 - anion helps enhancing the emission efficiency besides shifting the emission wavelengths.

Radiation-induced defect-formation in lithium hydride and deuteride monocrystals. [Electron and X-ray irradiation

Energy Technology Data Exchange (ETDEWEB)

Pustovarov, V.A.; Betenekova, T.A.; Zav' yalov, N.A.; Cholakh, S.O. (Ural' skij Politekhnicheskij Inst., Sverdlovsk (USSR))

1983-08-01

Methods of stationary and pulse absorption spectroscopy were used to investigate into processes of formation and decay of radiation defects in cubic LiH and LiD crystals. F- and V-centers form at low temperatures during crystal irradiation by photons, creating excitons selectively, accelerator electrons, X-ray radiation. Analysis of possible mechanisms of defect formation shows that radiation defect formation in LiH is based on radiationless exciton decay. It is shown that efficiency of F- and V-centers generation in pure and impure crystals in 80-298 K range is the same. Exciton decay with formation of Frenkel radiation defects in pure LiH and LiD crystals takes place, probably, in regular crystal lattice points. Process of radiation defect formation as a result of near activator exciton decay takes place in impure LiH-Na, LiD-Na crystals.

International Conference on Defects in Semiconductors (16th) Held in Bethlehem, Pennsylvania on 22-26 July 1991

Science.gov (United States)

1992-04-30

defects in crystalline silicon B.G. Svensson and M.O. Aboelfotoh PL .0 Interaction of a copper-induced defect with shallow acceptors and deep centers in...Electronics P.O. Box 1298, S-164 28 Kista-Stockholm, Sweden M.O. Aboelfotoh IBM Research Division, TJ. Watson Research Center P.O. Box 218, Yorktown Heights

Phase-enhanced defect sensitivity for EUV mask inspection

Science.gov (United States)

Wang, Yow-Gwo; Miyakawa, Ryan; Chao, Weilun; Goldberg, Kenneth; Neureuther, Andy; Naulleau, Patrick

2014-10-01

In this paper, we present a complete study on mask blank and patterned mask inspection utilizing the Zernike phase contrast method. The Zernike phase contrast method provides in-focus inspection ability to study phase defects with enhanced defect sensitivity. However, the 90 degree phase shift in the pupil will significantly reduce the amplitude defect signal at focus. In order to detect both types of defects with a single scan, an optimized phase shift instead of 90 degree on the pupil plane is proposed to achieve an acceptable trade-off on their signal strengths. We can get a 70% of its maximum signal strength at focus for both amplitude and phase defects with a 47 degree phase shift. For SNR, the tradeoff between speckle noise and signal strength has to be considered. The SNR of phase and amplitude defects at focus can both reach 11 with 13 degree phase shift and 50% apodization. Moreover, the simulation results on patterned mask inspection of partially hidden phase defects with die-to-database inspection approach on the blank inspection tool show that the improvement of the Zernike phase method is more limited. A 40% enhancement of peak signal strength can be achieved with the Zernike phase contrast method when the defect is centered in the space, while the enhancement drops to less than 10% when it is beneath the line.

A case difficult to diagnose in adults: High sinus venous atrial septal defect

Directory of Open Access Journals (Sweden)

Ozge Cetinarslan

2018-01-01

Full Text Available Sinus venous atrial septal defect (SVD is highly difficult to diagnose because of its location. Below, we report a case of SVD which is misdiagnosed as pulmonary hypertension and anomalous pulmonary venous return. A 57-year-old female patient was referred to congenital disease outpatient clinic of a tertiary center. She was admitted to the hospital with complaints of fatigue and exercise dyspnea which had started a year ago. She had transthoracic echocardiography (TTE examination done in another hospital which showed dilated right heart chambers and pulmonary hypertension. She underwent transesophageal echocardiography (TEE examination with the suspicion of atrial septal defect (ASD, but no defect was seen. As her symptoms persisted, we repeated the TTE and TEE examination in our center. TEE revealed 0.6 cm ASD on the upper side of the interatrial septum. All four pulmonary veins were draining into the left atrium. Right heart catheterization (RHC confirmed the diagnosis. A left-to-right shunt was detected and localized by a significant step-up in blood oxygen saturation found between mid and upper segments of the right atrium. According to our TEE and RHC results, we planned the surgical closure of the defect. Sinus venous ASD is deficiency of the superior portion of atrial septum adjacent to superior vena cava. Diagnosis of SVD is often more difficult than other forms of ASD and may require special imaging such as TEE, magnetic resonance imaging, or computed tomographic scanning. In conclusion, cardiologists must be aware about the possibility of SVD patients who have unexplained exertional dyspnea and fatigue, dilated right atrium and ventricle, pulmonary hypertension, paradoxical embolism, or atrial arrhythmias in their respective populations.

An atomistic vision of the Mass Action Law: Prediction of carbon/oxygen defects in silicon

Energy Technology Data Exchange (ETDEWEB)

Brenet, G.; Timerkaeva, D.; Caliste, D.; Pochet, P. [CEA, INAC-SP2M, Atomistic Simulation Laboratory, F-38000 Grenoble (France); Univ. Grenoble Alpes, INAC-SP2M, L-Sim, F-38000 Grenoble (France); Sgourou, E. N.; Londos, C. A. [University of Athens, Solid State Physics Section, Panepistimiopolis Zografos, Athens 157 84 (Greece)

2015-09-28

We introduce an atomistic description of the kinetic Mass Action Law to predict concentrations of defects and complexes. We demonstrate in this paper that this approach accurately predicts carbon/oxygen related defect concentrations in silicon upon annealing. The model requires binding and migration energies of the impurities and complexes, here obtained from density functional theory (DFT) calculations. Vacancy-oxygen complex kinetics are studied as a model system during both isochronal and isothermal annealing. Results are in good agreement with experimental data, confirming the success of the methodology. More importantly, it gives access to the sequence of chain reactions by which oxygen and carbon related complexes are created in silicon. Beside the case of silicon, the understanding of such intricate reactions is a key to develop point defect engineering strategies to control defects and thus semiconductors properties.

Evolution of E-centers during the annealing of Sb-doped Si0.8Ge0.2

DEFF Research Database (Denmark)

Kilpeläinen, S.; Tuomisto, F.; Slotte, J.

2011-01-01

Evolution of the chemical surroundings of vacancy complexes in Sb-doped ([Sb] = 2 × 1018 and 2 × 1019 cm−3) Si0.8Ge0.2 was studied with positron annihilation spectroscopy in Doppler broadening mode. The study was performed by annealing the samples both isochronally and isothermally. Defect...... evolution was observed at the temperature range 450–650 K. Both treatments were shown to induce changes in the chemical surroundings of the E-centers via introduction of Ge near the defects. Moreover, Sb was found to hinder these changes by stabilizing the E-centers and thus preventing them from finding Ge....... The stable state reached after the anneals was found to differ from that measured from an as-grown sample. This difference was deemed to be the result of Ge gathering in small clusters during the annealing thus breaking the initially random Ge distribution....

End-to-end probability for an interacting center vortex world line in Yang-Mills theory

International Nuclear Information System (INIS)

Teixeira, Bruno F.I.; Lemos, Andre L.L. de; Oxman, Luis E.

2011-01-01

Full text: The understanding of quark confinement is a very important open problem in Yang-Mills theory. In this regard, nontrivial topological defects are expected to play a relevant role to achieve a solution. Here we are interested in how to deal with these structures, relying on the Cho-Faddeev-Niemi decomposition and the possibility it offers to describe defects in terms of a local color frame. In particular, the path integral for a single center vortex is a fundamental object to handle the ensemble integration. As is well-known, in three dimensions center vortices are string-like and the associated physics is closely related with that of polymers. Using recent techniques developed in the latter context, we present in this work a detailed derivation of the equation for the end-to-end probability for a center vortex world line, including the effects of interactions. Its solution can be associated with a Green function that depends on the position and orientation at the boundaries, where monopole-like instantons are placed. In the limit of semi flexible polymers, an expansion only keeping the lower angular momenta for the final orientation leads to a reduced Green function for a complex vortex field minimally coupled to the dual Yang-Mills fields. This constitutes a key ingredient to propose an effective model for correlated monopoles, center vortices and the dual fields. (author)

Building diversity in a complex academic health center.

Science.gov (United States)

South-Paul, Jeannette E; Roth, Loren; Davis, Paula K; Chen, Terence; Roman, Anna; Murrell, Audrey; Pettigrew, Chenits; Castleberry-Singleton, Candi; Schuman, Joel

2013-09-01

For 30 years, the many diversity-related health sciences programs targeting the University of Pittsburgh undergraduate campus, school of medicine, schools of the health sciences, clinical practice plan, and medical center were run independently and remained separate within the academic health center (AHC). This lack of coordination hampered their overall effectiveness in promoting diversity and inclusion. In 2007, a group of faculty and administrators from the university and the medical center recognized the need to improve institutional diversity and to better address local health disparities. In this article, the authors describe the process of linking the efforts of these institutions in a way that would be successful locally and applicable to other academic environments. First, they engaged an independent consultant to conduct a study of the AHC's diversity climate, interviewing current and former faculty and trainees to define the problem and identify areas for improvement. Next, they created the Physician Inclusion Council to address the findings of this study and to coordinate future efforts with institutional leaders. Finally, they formed four working committees to address (1) communications and outreach, (2) cultural competency, (3) recruitment, and (4) mentoring and retention. These committees oversaw the strategic development and implementation of all diversity and inclusion efforts. Together these steps led to structural changes within the AHC and the improved allocation of resources that have positioned the University of Pittsburgh to achieve not only diversity but also inclusion and to continue to address the health disparities in the Pittsburgh community.

Defect reactions on the phosphorus sublattice in low-temperature electron-irradiated InP

International Nuclear Information System (INIS)

Sibille, A.; Suski, J.

1985-01-01

This Rapid Communication describes several thermally or electronically stimulated defect reactions involving the dominant deep centers in low-temperature (25--300 K) electron-irradiated InP. Some of these reactions result in an increased concentration of the centers, thereby revealing the existence of a secondary production mechanism of the related defects. Low-energy irradiations allows one to select the type of the ejected atom (P) and gives direct evidence that only a phosphorus species, interstitial or vacancy, is involved in the creation-reaction-annealing events

Tailoring defect structure and optical absorption of porous anodic aluminum oxide membranes

International Nuclear Information System (INIS)

Yan Hongdan; Lemmens, Peter; Wulferding, Dirk; Shi, Jianmin; Becker, Klaus Dieter; Lin, Chengtian; Lak, Aidin; Schilling, Meinhard

2012-01-01

Defects influence the optical and electronic properties of nanostructured materials that may be relevant for applications. In self-organized anodic aluminum oxide (AAO) templates we have investigated the effect of annealing, doping and nanoscale metal deposition. Optical absorption spectroscopy has been used as a sensitive probe for the defect density in AAO templates. The electronic spectra are found to be dominated by bands which originate from oxygen-deficient color centers (F + , F and F 2 ). In annealing studies, the integrated absorption of the bands changes non-monotonically with annealing temperature and annealing time. This demonstrates that the concentration of defects can be optimized to tailor the optical properties of the AAO. Metallic Au wires are deposited in the template to establish a plasmonic template or array. The investigations provide an interesting insight into the interplay of reactivity and diffusivity on nanoscales. - Highlights: ► Preparation of metal wire arrays in oxide templates with tailored plasmonic properties. ► Oxygen defects are characterized using optical absorption and fluorescence. ► Optical absorption spectra are assigned to energy levels of oxygen vacancies (color centers). ► Annealing and electrodeposition of Au wires minimize defects maintaining the morphology.

Cor triatriatum dexter and atrial septal defect in a 43-year-old woman.

Science.gov (United States)

Vukovic, Petar M; Kosevic, Dragana; Milicic, Miroslav; Jovovic, Ljiljana; Stojanovic, Ivan; Micovic, Slobodan

2014-08-01

Cor triatriatum dexter is a rare congenital heart anomaly in which a membrane divides the right atrium into 2 chambers. We report the case of a 43-year-old woman who had cor triatriatum dexter and a large atrial septal defect. During attempted percutaneous closure, the balloon disrupted the membrane and revealed that the defect had no inferior rim, precluding secure placement of an Amplatzer Septal Occluder. Surgical treatment subsequently proved to be successful. In patients with an incomplete membrane and a septal defect with well-defined rims, percutaneous treatment can be the first choice. In patients who have cor triatriatum dexter and unfavorable anatomic features or concomitant complex heart anomalies, open-heart surgery remains the gold standard for treatment.

The center for plant and microbial complex carbohydrates at the University of Georgia Complex Carbohydrate Research Center

Energy Technology Data Exchange (ETDEWEB)

Albersheim, P.; Darvill, A.

1991-08-01

Research from the Complex Carbohydrates Research Center at the University of Georgia is presented. Topics include: Structural determination of soybean isoflavones which specifically induce Bradyrhizobium japonicum nodD1 but not the nodYABCSUIJ operon; structural analysis of the lipopolysaccharides (LPSs) from symbiotic mutants of Bradyrhizobium japonicum; structural characterization of lipooligosaccharides from Bradyrhizobium japonicum that are required for the specific nodulation of soybean; structural characterization of the LPSs from R. Leguminosarum biovar phaseoli, the symbiont of bean; characterization of bacteroid-specific LPS epitopes in R. leguminosarum biovar viciae; analysis of the surface polysaccharides of Rhizobium meliloti mutants whose lipopolysaccharides and extracellular polysaccharides can have the same function in symbiosis; characterization of a polysaccharide produced by certain Bradyrhizobium japonicum strains within soybean nodules; structural analysis of a streptococcal adhesin polysaccharide receptor; conformational studies of xyloglucan, the role of the fucosylated side chain in surface-specific cellulose-xyloglucan interactions; the structure of an acylated glucosamine oligosaccharide signal molecule (nod factor) involved in the symbiosis of Rhizobium leguminosarum biovar viciae with its host Vicia sativa; investigating membrane responses induced by oligogalacturonides in cultured cells; the polygalacturonase inhibitor protein; characterization of the self-incompatability glycoproteins from Petunia hybrida; investigation of the cell wall polysaccharide structures of Arabidopsis thaliana; and the glucan inhibition of virus infection of tabacco.

Complex Interaction Mechanisms between Dislocations and Point Defects Studied in Pure Aluminium by a Two-Wave Acoustic Coupling Technique

Science.gov (United States)

Bremnes, O.; Progin, O.; Gremaud, G.; Benoit, W.

1997-04-01

Ultrasonic experiments using a two-wave coupling technique were performed on 99.999% pure Al in order to study the interaction mechanisms occurring between dislocations and point defects. The coupling technique consists in measuring the attenuation of ultrasonic waves during low-frequency stress cycles (t). One obtains closed curves () called signatures whose shape and evolution are characteristic of the interaction mechanism controlling the low-frequency dislocation motion. The signatures observed were attributed to the interaction of the dislocations with extrinsic point defects. A new interpretation of the evolution of the signatures measured below 200 K with respect to temperature and stress frequency had to be established: they are linked to depinning of immobile point defects, whereas a thermally activated depinning mechanism does not fit the observations. The signatures measured between 200 and 370 K were interpreted as dragging and depinning of extrinsic point defects which are increasingly mobile with temperature.

Evolution of defects in a multicomponent glass irradiated by 1 MeV electrons

International Nuclear Information System (INIS)

Wang Qingyan; Geng Hongbin; Sun Chengyue; Zhang Zhonghua; He Shiyu

2010-01-01

The optical properties and microstructural degradation of a multicomponent glass after exposure to 1 MeV electrons for fluences of 10 13 to 10 16 e - /cm 2 , as well as the recovery during annealing at room temperature (RT) for the fluence of 10 16 e - /cm 2 , are investigated. The non-bridging oxygen hole centers (NBOHCs), as well as trapped electrons (TEs), are mainly attributed to optical absorption bands and paramagnetic spectra. In comparison of the exponential curves, the in-growth kinetics for each type of defect with increasing fluence are separable, and a new linearly-combined exponential model is used to describe the structural responses during irradiation. Accordingly, RT bleaching curves of defects follow a linearly-combined exponential decay function. Consistent results from optical and paramagnetic signals suggest that this linearly-combined model provides a reasonable kinetic description of the growth and bleaching process of defects.

Modeling of extended defects in silicon

International Nuclear Information System (INIS)

Law, M.E.; Jones, K.S.; Earles, S.K.; Lilak, A.D.; Xu, J.W.

1997-01-01

Transient Enhanced Diffusion (TED) is one of the biggest modeling challenges present in predicting scaled technologies. Damage from implantation of dopant ions changes the diffusivities of the dopants and precipitates to form complex extended defects. Developing a quantitative model for the extended defect behavior during short time, low temperature anneals is a key to explaining TED. This paper reviews some of the modeling developments over the last several years, and discusses some of the challenges that remain to be addressed. Two examples of models compared to experimental work are presented and discussed

Anatomy of a wrong diagnosis: false Sinus Venosus Atrial Septal Defect

Directory of Open Access Journals (Sweden)

Montresor Graziano

2003-11-01

Full Text Available Abstract In contrast with transthoracic echocardiography, transesophageal echocardiography provides a sure way to make the diagnosis of sinus venosus atrial septal defect; on the other hand this abnormality is more complex than that seen with the secundum atrial septal defect, and inexperienced operators may fail to recognize properly the defect. In front of a high reported sensitivity using transesophageal echocardiography, specificity is difficult to assess, due to possible underreporting of diagnostic errors. We describe a false positive diagnosis of sinus venosus atrial septal defect, in the setting of enlarged right chambers of the heart because of pressure overload. Modified anatomy of the heart, together with the presence of a prominent linear structure(probably Eustachian Valve and an incomplete examination in this case made image interpretation very prone to misinterpretation. In this anatomical setting transesophageal longitudinal "bicaval" view may be sub-optimal for examining the atrial septum, potentially showing false images that need to be known for correct image interpretation. Nonetheless, a scan plane taken more accurately at the superior level would have demonstrated/excluded the pathognomonic feature of sinus venosus atrial septal defect in the high atrial septum, between the fatty limbus and the inferior aspect of the right pulmonary artery; moreover TEE allows morphological information about the posterior structures of the heart that need to be investigated in detail for a complete diagnosis.

Rabbit Calvarial Defect Model for Customized 3D-Printed Bone Grafts.

Science.gov (United States)

Lee, Kang-Gon; Lee, Kang-Sik; Kang, Yu-Jeoung; Hwang, Jong-Hyun; Lee, Se-Hwan; Park, Sang-Hyug; Park, Yongdoo; Cho, Young-Sam; Lee, Bu-Kyu

2018-05-01

Bone graft materials are commonly used to regenerate various bone defects, but their application is often limited because of the complex defect shape in various clinical conditions. Hence, customized bone grafts using three-dimensional (3D) printing techniques have been developed. However, conventional simple bone defect models are limited for evaluating the benefits and manufacturing accuracy of 3D-printed customized bone grafts. Thus, the aim of the present study was to develop a complex-shaped bone defect model. We designed an 8-shaped bony defect that consists of two simple circles attached to the rabbit calvarium. To determine the critical-sized defect (CSD) of the 8-shaped defects, 5.6- and 7-mm-diameter trephine burs were tested, and the 7-mm-diameter bur could successfully create a CSD, which was easily reproducible on the rabbit calvarium. The rate of new bone formation was 28.65% ± 8.63% at 16 weeks following creation of the defect. To confirm its efficacy for clinical use, the 8-shaped defect was created on a rabbit calvarium and 3D computed tomography (CT) was performed. A stereolithography file was produced using the CT data, and a 3D-printed polycaprolactone graft was fabricated. Using our 8-shaped defect model, we were able to modify the tolerances of the bone graft and calvarial defect to fabricate a more precise bone graft. Customized characteristics of the bone graft were then used to improve the accuracy of the bone graft. In addition, we confirmed the fitting ability of the 3D-printed graft during implantation of the graft. Our 8-shaped defect model on the rabbit calvarium using a 7.0-mm trephine bur may be a useful CSD model for evaluating 3D-printed graft materials.

Gerbode defect and multivalvular dysfunction: Complex complications in adult congenital heart disease.

Science.gov (United States)

Ruivo, Catarina; Guardado, Joana; Montenegro Sá, Fernando; Saraiva, Fátima; Antunes, Alexandre; Correia, Joana; Morais, João

2017-07-01

We report a clinical case of a 40-year-old male with surgically corrected congenital heart disease (CHD) 10 years earlier: closure of ostium primum, mitral annuloplasty, and aortic valve and root surgery. The patient was admitted with acute heart failure. Transesophageal echocardiography (TEE) revealed a dysmorphic and severely incompetent aortic valve, a partial tear of the mitral valve cleft repair and annuloplasty ring dehiscence. A true left ventricular-to-right atrial shunt confirmed a direct Gerbode defect. The authors aim to discuss the diagnostic challenge of adult CHD, namely the key role of TEE on septal defects and valve regurgitations description. © 2017, Wiley Periodicals, Inc.

Radiation defects in SrB4O7:Eu2+ crystals

International Nuclear Information System (INIS)

Yavetskiy, R.P.; Dolzhenkova, E.F.; Tolmachev, A.V.; Parkhomenko, S.V.; Baumer, V.N.; Prosvirnin, A.L.

2007-01-01

Radiation-induced defects in SrB 4 O 7 :Eu 2+ (0.033 at.%) single crystal irradiated with γ and X-ray quanta has been studied. The induced optical absorption in the 400-700 nm region has been ascribed to F + centers. The Eu 2+ ions have been shown to act simultaneously as traps and as radiative recombination centers of charge carriers. Basing on the thermally stimulated luminescence (TSL), optical absorption and photoluminescence studies of SrB 4 O 7 :Eu 2+ crystals, a TSL mechanism has been proposed associated with the decay of F + centers being in non-equivalent crystallographic positions followed by radiative recombination of charge carriers on europium ions. Various positions of localization of the radiation-induced defects in the SrB 4 O 7 crystal structure have been discussed

Mechanism for radiative recombination and defect properties of GaP/GaNP core/shell nanowires

International Nuclear Information System (INIS)

Dobrovolsky, A.; Stehr, J. E.; Chen, S. L.; Chen, W. M.; Buyanova, I. A.; Kuang, Y. J.; Sukrittanon, S.; Tu, C. W.

2012-01-01

Recombination processes in GaP/GaNP core/shell nanowires (NWs) grown on a Si substrate by molecular beam epitaxy are examined using a variety of optical characterization techniques, including cw- and time-resolved photoluminescence and optically detected magnetic resonance (ODMR). Superior optical quality of the structures is demonstrated based on the observation of intense emission from a single NW at room temperature. This emission is shown to originate from radiative transitions within N-related localized states. From ODMR, growth of GaP/GaNP NWs is also found to facilitate formation of complex defects containing a P atom at its core that act as centers of competing non-radiative recombination.

The reverse sural artery fasciomusculocutaneous flap for small lower-limb defects: the use of the gastrocnemius muscle cuff as a plug for small bony defects following debridement of infected/necrotic bone.

Science.gov (United States)

Al-Qattan, M M

2007-09-01

The reverse sural artery fasciomusculocutaneous flap is a modification of the original fasciocutaneous flap in which a midline gastrocnemius muscle cuff around the buried sural pedicle is included in the flap. This modification was done to improve the blood supply of the distal part of the flap, which is harvested from the upper leg. The aim of this paper is to demonstrate that there is another important advantage of the modified flap: the use of the muscle cuff as a "plug" for small lower limb defects following debridement of infected/necrotic bone. A total of 10 male adult patients with small complex lower-limb defects with underlying bone pathology were treated with the modified flap using the muscle component to fill up the small bony defects. The bony pathology included necrotic exposed bone without evidence of osteomyelitis or wound infection (n = 1), an underlying neglected tibial fracture with wound infection (n = 4), and a sinus at the heel with underlying calcaneal osteomyelitis (n = 5). Primary wound healing of the flap into the defect was noted in all patients. No recurrence of calcaneal osteomyelitis was seen and all tibial fractures united following appropriate orthopedic fixation. It was concluded that the reverse sural artery fasciomusculocutaneous flap is well suited for small complex lower-limb defects with underlying bone pathology.

Magnetic circular dichroism study of electron-irradiation induced defects in InP

International Nuclear Information System (INIS)

Gislason, H.P.

1989-01-01

A strong magnetic circular dichroism (MCD) absorption band centered at 1.07 eV in electron irradiated InP is reported. Temperature and magnetic field dependence of the signal reveal that the centre giving rise to this band is a spin triplet. By simulating neutral and reverse bias conditions of junction measurements through a careful choice of irradiation dose and starting material, the MCD band is shown to have an annealing behaviour closely resembling that of the majority carrier traps which control the Fermi level position in n- and p-type InP. The 1.07 eV MCD band represents the first magneto-optical signal connected with this family of complex irradiation-induced defects in InP. (author) 19 refs., 5 figs., 1 tab

The effect of defects on structural failure: A two-criteria approach

International Nuclear Information System (INIS)

Dowling, A.R.; Townley, C.H.A.

1976-01-01

The two-criteria approach to the study of defects in structures assumes that failure occurs when the applied load reaches the lower of either a load to cause brittle failure in accordance with the theories of linear elastic fracture mechanics or a collapse load dependent on the ultimate stress of the material and the structural geometry. This simple approach is described and compared with previously published experimental results for various geometries and materials. The simplicity of this method of defect analysis lies in the fact that each criterion is sufficiently well understood to permit scaling and geometry changes to be accommodated readily. It becomes apparent that a sizeable transition region exists between the two criteria but this can be described in an expression relating the criteria. This expression adequately predicts the behaviour of cracked structures of both simple and complex geometry. A design curve for defect assessment is proposed for which it is unnecessary to consider the transition region. (author)

Nanocarbon: Defect Architectures and Properties

Science.gov (United States)

Vuong, Amanda

The allotropes of carbon make its solid phases amongst the most diverse of any element. It can occur naturally as graphite and diamond, which have very different properties that make them suitable for a wide range of technological and commercial purposes. Recent developments in synthetic carbon include Highly Oriented Pyrolytic Graphite (HOPG) and nano-carbons, such as fullerenes, nanotubes and graphene. The main industrial application of bulk graphite is as an electrode material in steel production, but in purified nuclear graphite form, it is also used as a moderator in Advanced Gas-cooled Reactors across the United Kingdom. Both graphene and graphite are damaged over time when subjected to bombardment by electrons, neutrons or ions, and these have a wide range of effects on their physical and electrical properties, depending on the radiation flux and temperature. This research focuses on intrinsic defects in graphene and dimensional change in nuclear graphite. The method used here is computational chemistry, which complements physical experiments. Techniques used comprise of density functional theory (DFT) and molecular dynamics (MD), which are discussed in chapter 2 and chapter 3, respectively. The succeeding chapters describe the results of simulations performed to model defects in graphene and graphite. Chapter 4 presents the results of ab initio DFT calculations performed to investigate vacancy complexes that are formed in AA stacked bilayer graphene. In AB stacking, carbon atoms surrounding the lattice vacancies can form interlayer structures with sp2 bonding that are lower in energy compared to in-plane reconstructions. From the investigation of AA stacking, sp2 interlayer bonding of adjacent multivacancy defects in registry creates a type of stable sp2 bonded wormhole between the layers. Also, a new class of mezzanine structure characterised by sp3 interlayer bonding, resembling a prismatic vacancy loop has also been identified. The mezzanine, which is a

Point defect states in Sb-doped germanium

Energy Technology Data Exchange (ETDEWEB)

Patel, Neil S., E-mail: neilp@mit.edu; Monmeyran, Corentin, E-mail: comonmey@mit.edu [Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, Massachusetts 02139 (United States); Agarwal, Anuradha [Microphotonics Center, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, Massachusetts 02139 (United States); Kimerling, Lionel C. [Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, Massachusetts 02139 (United States); Microphotonics Center, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, Massachusetts 02139 (United States)

2015-10-21

Defect states in n-type Sb-doped germanium were investigated by deep-level transient spectroscopy. Cobalt-60 gamma rays were used to generate isolated vacancies and interstitials which diffuse and react with impurities in the material to form four defect states (E{sub 37}, E{sub 30}, E{sub 22}, and E{sub 21}) in the upper half of the bandgap. Irradiations at 77 K and 300 K as well as isothermal anneals were performed to characterize the relationships between the four observable defects. E{sub 37} is assigned to the Sb donor-vacancy associate (E-center) and is the only vacancy containing defect giving an estimate of 2 × 10{sup 11 }cm{sup −3} Mrad{sup −1} for the uncorrelated vacancy-interstitial pair introduction rate. The remaining three defect states are interstitial associates and transform among one another. Conversion ratios between E{sub 22}, E{sub 21}, and E{sub 30} indicate that E{sub 22} likely contains two interstitials.

Arabidopsis thaliana plants lacking the ARP2/3 complex show defects in cell wall assembly and auxin distribution.

Science.gov (United States)

Pratap Sahi, Vaidurya; Cifrová, Petra; García-González, Judith; Kotannal Baby, Innu; Mouillé, Gregory; Gineau, Emilie; Müller, Karel; Baluška, František; Soukup, Aleš; Petrášek, Jan; Schwarzerová, Katerina

2017-12-25

The cytoskeleton plays an important role in the synthesis of plant cell walls. Both microtubules and actin cytoskeleton are known to be involved in the morphogenesis of plant cells through their role in cell wall building. The role of ARP2/3-nucleated actin cytoskeleton in the morphogenesis of cotyledon pavement cells has been described before. Seedlings of Arabidopsis mutants lacking a functional ARP2/3 complex display specific cell wall-associated defects. In three independent Arabidopsis mutant lines lacking subunits of the ARP2/3 complex, phenotypes associated with the loss of the complex were analysed throughout plant development. Organ size and anatomy, cell wall composition, and auxin distribution were investigated. ARP2/3-related phenotype is associated with changes in cell wall composition, and the phenotype is manifested especially in mature tissues. Cell walls of mature plants contain less cellulose and a higher amount of homogalacturonan, and display changes in cell wall lignification. Vascular bundles of mutant inflorescence stems show a changed pattern of AUX1-YFP expression. Plants lacking a functional ARP2/3 complex have decreased basipetal auxin transport. The results suggest that the ARP2/3 complex has a morphogenetic function related to cell wall synthesis and auxin transport. © The Author(s) 2017. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Study of crystalline defects in α-iron

International Nuclear Information System (INIS)

Dunlop, A.

1981-01-01

We study here the configurations of the defects produced in ferromagnetic metals (Fe, Co, Ni) during low-temperature irradiations. In the first part we find an anomalous shape of the damage production rate curves Δrho(.)(Δrho) (Δrho: resistivity increase; Δrho(.)=dΔrho/dPHI; PHI: irradiation fluence) of iron and nickel during neutron irradiations. We propose the following interpretation: - stability of the defect configurations created during low-temperature self-ion irradiations of these metals; - instability of these defect configurations where there is a sufficient cascade overlap. This agglomeration leads to a decrease of the average resistivity of the defects. Using this model, we can reproduce the iron results with the following parameters: - characteristic volume for the recovery: 3.3 x 10 -18 cm 3 ; - division of the average resistivity of the defects by 2.3 to 3 when they agglomerate. In the second part we study the influence of irradiation defects on the longitudinal magnetoresistance of the samples. The increase in the number of scattering centers (n, e - irradiations) makes the resistivity anisotropy (deltarho=rho// - rho perpendicular) change gradually from a region in which the 'normal' magnetoresistance is predominant to another in which the spontaneous anisotropy dominates. This last regime is studied with the two-current conduction model in ferromagnetics [fr

The SWI/SNF BAF-A complex is essential for neural crest development.

Science.gov (United States)

Chandler, Ronald L; Magnuson, Terry

2016-03-01

Growing evidence indicates that chromatin remodeler mutations underlie the pathogenesis of human neurocristopathies or disorders that affect neural crest cells (NCCs). However, causal relationships among chromatin remodeler subunit mutations and NCC defects remain poorly understood. Here we show that homozygous loss of ARID1A-containing, SWI/SNF chromatin remodeling complexes (BAF-A) in NCCs results in embryonic lethality in mice, with mutant embryos succumbing to heart defects. Strikingly, monoallelic loss of ARID1A in NCCs led to craniofacial defects in adult mice, including shortened snouts and low set ears, and these defects were more pronounced following homozygous loss of ARID1A, with the ventral cranial bones being greatly reduced in size. Early NCC specification and expression of the BRG1 NCC target gene, PLEXINA2, occurred normally in the absence of ARID1A. Nonetheless, mutant embryos displayed incomplete conotruncal septation of the cardiac outflow tract and defects in the posterior pharyngeal arteries, culminating in persistent truncus arteriosus and agenesis of the ductus arteriosus. Consistent with this, migrating cardiac NCCs underwent apoptosis within the circumpharyngeal ridge. Our data support the notion that multiple, distinct chromatin remodeling complexes govern genetically separable events in NCC development and highlight a potential pathogenic role for NCCs in the human BAF complex disorder, Coffin-Siris Syndrome. Copyright © 2016 Elsevier Inc. All rights reserved.

N+ ion-implantation-induced defects in ZnO studied with a slow positron beam

International Nuclear Information System (INIS)

Chen, Z Q; Sekiguchi, T; Yuan, X L; Maekawa, M; Kawasuso, A

2004-01-01

Undoped ZnO single crystals were implanted with multiple-energy N + ions ranging from 50 to 380 keV with doses from 10 12 to 10 14 cm -2 . Positron annihilation measurements show that vacancy defects are introduced in the implanted layers. The concentration of the vacancy defects increases with increasing ion dose. The annealing behaviour of the defects can be divided into four stages, which correspond to the formation and recovery of large vacancy clusters and the formation and disappearance of vacancy-impurity complexes, respectively. All the implantation-induced defects are removed by annealing at 1200 deg. C. Cathodoluminescence measurements show that the ion-implantation-induced defects act as nonradiative recombination centres to suppress the ultraviolet (UV) emission. After annealing, these defects disappear gradually and the UV emission reappears, which coincides with positron annihilation measurements. Hall measurements reveal that after N + implantation, the ZnO layer still shows n-type conductivity

Multi-frequency EDMR studies of light-activated paramagnetic centers in μc-Si:H thin-film solar cells

International Nuclear Information System (INIS)

Meier, Christoph

2014-01-01

This thesis presents a comprehensive study of paramagnetic centers in fully-processed microcrystalline silicon (μc-Si:H) thin-film solar cells. The heterogeneous material gives rise to a complex band structure with deep defects in the middle of the energy band gap as well as localized states close to the energy band edges. They can act as recombination centers and traps and, thereby, influence the charge transport of photogenerated charge carriers. Thus, they diminish the performance of the cell. To reduce the disadvantageous influence of the defect states on the cell efficiency, a detailed understanding of the charge transport processes via these states is necessary. In this work, light-activated paramagnetic centers are studied with electrically detected magnetic resonance (EDMR) at various microwave frequencies. This technique combines electron paramagnetic resonance spectroscopy (EPR) with the photocurrent measurement in the solar cell, thus, delivering information about the transport processes and magnetic parameters of the involved defect states. Multi-frequency EDMR at low temperatures reveals four paramagnetic states in μc-Si:H. Dangling bond (db) defects and holes in valence band tail (h) states are located in the disordered phase, whereas so-called CE and V states originate from the crystalline phase. The multi-frequency approach allows for a separation of field-dependent and -independent line widths. All EDMR signals are affected by line broadening due to spin-spin interaction, which could be used to estimate mean inter-spin distances of around ∼ 0.5 nm for the V center and of ∼ 1-2 nm for the remaining centers. Based on the strong spin-spin coupling and on transient nutation experiments the V signal could be correlated with a vacancy site in its excited triplet state. From the particular properties of the CE line it was concluded that the corresponding states are located in inversion layers and potential wells close to the conduction band of

Multimodality Renal Failure in a Patient with OEIS Complex

Directory of Open Access Journals (Sweden)

Jonathan D. Santoro

2015-10-01

Full Text Available Omphalocele-exstrophy of the bladder-imperforate anus-spinal defect (OEIS complex is a rare constellation of clinical abnormalities with wide phenotypic presentation. We describe a case of a preterm neonate with OEIS complex with acute renal failure, and the challenges in diagnosis and management of this patient as renal failure can be a multifactorial process when encountered with this rare complex.

Spontaneous symmetry breaking, and strings defects in hypercomplex gauge field theories

Energy Technology Data Exchange (ETDEWEB)

Cartas-Fuentevilla, R. [Universidad Autonoma de Puebla, Instituto de Fisica, Puebla, Pue. (Mexico); Meza-Aldama, O. [Universidad Autonoma de Puebla, Facultad de Ciencias Fisico-Matematicas, Puebla, Pue. (Mexico)

2016-02-15

Inspired by the appearance of split-complex structures in the dimensional reduction of string theory, and in the theories emerging as byproducts, we study the hypercomplex formulation of Abelian gauge field theories by incorporating a new complex unit to the usual complex one. The hypercomplex version of the traditional Mexican hat potential associated with the U(1) gauge field theory, corresponds to a hybrid potential with two real components, and with U(1) x SO(1,1) as symmetry group. Each component corresponds to a deformation of the hat potential, with the appearance of a new degenerate vacuum. Hypercomplex electrodynamics will show novel properties, such as spontaneous symmetry breaking scenarios with running masses for the vectorial and scalar Higgs fields, and such as Aharonov-Bohm type strings defects as exact solutions; these topological defects may be detected only by quantum interference of charged particles through gauge invariant loop integrals. In a particular limit, the hyperbolic electrodynamics does not admit topological defects associated with continuous symmetries. (orig.)

VV and VO2 defects in silicon studied with hybrid density functional theory

KAUST Repository

Christopoulos, Stavros Richard G; Wang, Hao; Chroneos, Alexander I.; Londos, Charalampos A.; Sgourou, Efstratia N.; Schwingenschlö gl, Udo

2014-01-01

The formation of VO (A-center), VV and VO2 defects in irradiated Czochralski-grown silicon (Si) is of technological importance. Recent theoretical studies have examined the formation and charge states of the A-center in detail. Here we use density

First-principles engineering of charged defects for two-dimensional quantum technologies

Science.gov (United States)

Wu, Feng; Galatas, Andrew; Sundararaman, Ravishankar; Rocca, Dario; Ping, Yuan

2017-12-01

Charged defects in two-dimensional (2D) materials have emerging applications in quantum technologies such as quantum emitters and quantum computation. The advancement of these technologies requires a rational design of ideal defect centers, demanding reliable computation methods for the quantitatively accurate prediction of defect properties. We present an accurate, parameter-free, and efficient procedure to evaluate the quasiparticle defect states and thermodynamic charge transition levels of defects in 2D materials. Importantly, we solve critical issues that stem from the strongly anisotropic screening in 2D materials, that have so far precluded the accurate prediction of charge transition levels in these materials. Using this procedure, we investigate various defects in monolayer hexagonal boron nitride (h -BN ) for their charge transition levels, stable spin states, and optical excitations. We identify CBVN (nitrogen vacancy adjacent to carbon substitution of boron) to be the most promising defect candidate for scalable quantum bit and emitter applications.

Radiation effects and defects in lithium borate crystals

Energy Technology Data Exchange (ETDEWEB)

Ogorodnikov, Igor N; Poryvay, Nikita E; Pustovarov, Vladimir A, E-mail: igor.ogorodnikov@bk.ru [Ural Federal University, Mira Street, 19, Ekaterinburg 620002 (Russian Federation)

2010-11-15

The paper presents the results of a study of the formation and decay of lattice defects in wide band-gap optical crystals of LiB{sub 3}O{sub 5} (LBO), Li{sub 2}B{sub 4}O{sub 7} (LTB) and Li{sub 6}Gd(BO{sub 3}){sub 3} (LGBO) with a sublattice of mobile lithium cations. By means of thermoluminescence techniques, and luminescent and absorption optical spectroscopy with a nanosecond time resolution under excitation with an electron beam, it was revealed that the optical absorption in these crystals in the visible and ultraviolet spectral ranges is produced by optical hole-transitions from the local defect level to the valence band states. The valence band density of the states determines mainly the optical absorption spectral profile, and the relaxation kinetics is rated by the interdefect non-radiative tunnel recombination between the trapped-hole center and the Li{sup 0} trapped-electron centers. At 290 K, the Li{sup 0} centers are subject to thermally stimulated migration. Based on experimental results, the overall picture of thermally stimulated recombination processes with the participation of shallow traps was established for these crystals.

Nuclear Pasta: Topology and Defects

Science.gov (United States)

da Silva Schneider, Andre; Horowitz, Charles; Berry, Don; Caplan, Matt; Briggs, Christian

2015-04-01

A layer of complex non-uniform phases of matter known as nuclear pasta is expected to exist at the base of the crust of neutron stars. Using large scale molecular dynamics we study the topology of some pasta shapes, the formation of defects and how these may affect properties of neutron star crusts.

Topological Defects in a Living Nematic Ensnare Swimming Bacteria

Science.gov (United States)

Genkin, Mikhail M.; Sokolov, Andrey; Lavrentovich, Oleg D.; Aranson, Igor S.

2017-01-01

Active matter exemplified by suspensions of motile bacteria or synthetic self-propelled particles exhibits a remarkable propensity to self-organization and collective motion. The local input of energy and simple particle interactions often lead to complex emergent behavior manifested by the formation of macroscopic vortices and coherent structures with long-range order. A realization of an active system has been conceived by combining swimming bacteria and a lyotropic liquid crystal. Here, by coupling the well-established and validated model of nematic liquid crystals with the bacterial dynamics, we develop a computational model describing intricate properties of such a living nematic. In faithful agreement with the experiment, the model reproduces the onset of periodic undulation of the director and consequent proliferation of topological defects with the increase in bacterial concentration. It yields a testable prediction on the accumulation of bacteria in the cores of +1 /2 topological defects and depletion of bacteria in the cores of -1 /2 defects. Our dedicated experiment on motile bacteria suspended in a freestanding liquid crystalline film fully confirms this prediction. Our findings suggest novel approaches for trapping and transport of bacteria and synthetic swimmers in anisotropic liquids and extend a scope of tools to control and manipulate microscopic objects in active matter.

Paramagnetic centers in nanocrystalline TiC/C system

International Nuclear Information System (INIS)

Guskos, N.; Bodziony, T.; Maryniak, M.; Typek, J.; Biedunkiewicz, A.

2008-01-01

Electron paramagnetic resonance is applied to study the defect centers in nanocrystalline titanium carbide dispersed in carbon matrix (TiC x /C) synthesized by the non-hydrolytic sol-gel process. The presence of Ti 3+ paramagnetic centers is identified below 120 K along with a minor contribution from localized defect spins coupled with the conduction electron system in the carbon matrix. The temperature dependence of the resonance intensity of the latter signal indicates weak antiferromagnetic interactions. The presence of paramagnetic centers connected with trivalent titanium is suggested to be the result of chemical disorder, which can be further related to the observed anomalous behavior of conductivity, hardness, and corrosion resistance of nanocrystalline TiC x /C

Dynamic properties of interstitial carbon and carbon-carbon pair defects in silicon

International Nuclear Information System (INIS)

Leary, P.; Jones, R.; Oeberg, S.; Torres, V.J.

1997-01-01

Interstitial carbon, C i , defects in Si exhibit a number of unexplained features. The C i defect in the neutral charge state gives rise to two almost degenerate vibrational modes at 920 and 931 cm -1 whose 2:1 absorption intensity ratio naturally suggests a trigonal defect in conflict with uniaxial stress measurements. The dicarbon, C s -C i , defect is bistable, and the energy difference between its A and B forms is surprisingly small even though the bonding is very different. In the B form appropriate to the neutral charge state, a silicon interstitial is believed to be located near a bond-centered site between two C s atoms. This must give rise to vibrational modes which involve the motion of both C atoms in apparent conflict with the results of photoluminescence experiments. We use an ab initio local density functional cluster method, AIMPRO, to calculate the structure and vibrational modes of these defects and find that the ratio of the absorption intensities of the local modes of C i is in reasonable agreement with experiment even though the structure of the defect is not trigonal. We also show that modes in the vicinity of those detected by photoluminescence for the B form of the dicarbon center involve independent movements of the two C atoms. Finally, the trends in the relative energies of the A and B forms in three charge states are investigated. copyright 1996 The American Physical Society

A defect in the thymidine kinase 2 gene causing isolated mitochondrial myopathy without mtDNA depletion.

Science.gov (United States)

Leshinsky-Silver, E; Michelson, M; Cohen, S; Ginsberg, M; Sadeh, M; Barash, V; Lerman-Sagie, T; Lev, D

2008-07-01

Isolated mitochondrial myopathies (IMM) are either due to primary defects in mtDNA, in nuclear genes that control mtDNA abundance and structure such as thymidine kinase 2 (TK2), or due to CoQ deficiency. Defects in the TK2 gene have been found to be associated with mtDNA depletion attributed to a depleted mitochondrial dNTP pool in non-dividing cells. We report an unusual case of IMM, homozygous for the H90N mutation in the TK2 gene but unlike other cases with the same mutation, does not demonstrate mtDNA depletion. The patient's clinical course is relatively mild and a muscle biopsy showed ragged red muscle fibers with a mild decrease in complexes I and an increase in complexes IV and II activities. This report extends the phenotypic expression of TK2 defects and suggests that all patients who present with an IMM even with normal quantities of mtDNA should be screened for TK2 mutations.

Chondrogenic Differentiation of Human Adipose-Derived Stem Cells: A New Path in Articular Cartilage Defect Management?

Directory of Open Access Journals (Sweden)

Jan-Philipp Stromps

2014-01-01

Full Text Available According to data published by the Centers for Disease Control and Prevention, over 6 million people undergo a variety of medical procedures for the repair of articular cartilage defects in the U.S. each year. Trauma, tumor, and age-related degeneration can cause major defects in articular cartilage, which has a poor intrinsic capacity for healing. Therefore, there is substantial interest in the development of novel cartilage tissue engineering strategies to restore articular cartilage defects to a normal or prediseased state. Special attention has been paid to the expansion of chondrocytes, which produce and maintain the cartilaginous matrix in healthy cartilage. This review summarizes the current efforts to generate chondrocytes from adipose-derived stem cells (ASCs and provides an outlook on promising future strategies.

Simplistic and complex thought in medicine: the rationale for a person-centered care model as a medical revolution

Directory of Open Access Journals (Sweden)

Reach G

2016-04-01

Full Text Available Gérard Reach1,2 1Department of Endocrinology, Diabetes and Metabolic Diseases, Avicenne Hospital AP-HP, 2EA 3412, Centre de Recherche en Nutrition Humaine Ile-de-France (CRNH-IDF, Paris 13 University, Sorbonne Paris Cité, Bobigny, France Abstract: According to the concept developed by Thomas Kuhn, a scientific revolution occurs when scientists encounter a crisis due to the observation of anomalies that cannot be explained by the generally accepted paradigm within which scientific progress has thereto been made: a scientific revolution can therefore be described as a change in paradigm aimed at solving a crisis. Described herein is an application of this concept to the medical realm, starting from the reflection that during the past decades, the medical community has encountered two anomalies that, by their frequency and consequences, represent a crisis in the system, as they deeply jeopardize the efficiency of care: nonadherence of patients who do not follow the prescriptions of their doctors, and clinical inertia of doctors who do not comply with good practice guidelines. It is proposed that these phenomena are caused by a contrast between, on the one hand, the complex thought of patients and doctors that sometimes escapes rationalization, and on the other hand, the simplification imposed by the current paradigm of medicine dominated by the technical rationality of evidence-based medicine. It is suggested therefore that this crisis must provoke a change in paradigm, inventing a new model of care defined by an ability to take again into account, on an individual basis, the complex thought of patients and doctors. If this overall analysis is correct, such a person-centered care model should represent a solution to the two problems of patients’ nonadherence and doctors’ clinical inertia, as it tackles their cause. These considerations may have important implications for the teaching and the practice of medicine. Keywords: person-centered

Lithium niobate. Defects, photorefraction and ferroelectric switching

Energy Technology Data Exchange (ETDEWEB)

Volk, Tatyana [Russian Academy of Sciences, Inst. for Crystallography, Moscow (Russian Federation); Woehlecke, Manfred [Osnabrueck Univ. (Germany). Fachbereich Physik

2008-07-01

The book presents the current state of studies of point defects, both intrinsic and extrinsic (impurities, radiation centers, etc.), in LiNbO{sub 3}. The contribution of intrinsic defects to photoinduced charge transport, i.e. to the photorefraction, is explained. The photorefractive and optical properties of LiNbO{sub 3} crystals with different stoichiometry and of those doped with so-called ''optical-damage resistant'' impurities controlling the intrinsic defect structure are described in detail. Applications included are to the problem of non-erasable recording of photorefractive holograms in LiNbO{sub 3} and the current situation of studies in the ferroelectric switching and domain structure of LiNbO{sub 3}, as well as the creation of periodically-poled structures for the optical frequency conversion. (orig.)

The Correlation Between Dislocations and Vacancy Defects Using Positron Annihilation Spectroscopy

Science.gov (United States)

Pang, Jinbiao; Li, Hui; Zhou, Kai; Wang, Zhu

2012-07-01

An analysis program for positron annihilation lifetime spectra is only applicable to isolated defects, but is of no use in the presence of defective correlations. Such limitations have long caused problems for positron researchers in their studies of complicated defective systems. In order to solve this problem, we aim to take a semiconductor material, for example, to achieve a credible average lifetime of single crystal silicon under plastic deformation at different temperatures using positron life time spectroscopy. By establishing reasonable positron trapping models with defective correlations and sorting out four lifetime components with multiple parameters, as well as their respective intensities, information is obtained on the positron trapping centers, such as the positron trapping rates of defects, the density of the dislocation lines and correlation between the dislocation lines, and the vacancy defects, by fitting with the average lifetime with the aid of Matlab software. These results give strong grounds for the existence of dislocation-vacancy correlation in plastically deformed silicon, and lay a theoretical foundation for the analysis of positron lifetime spectra when the positron trapping model involves dislocation-related defects.

Ferromagnetically coupled local moments along an extended line defect in graphene

Science.gov (United States)

White, Carter T.; Vasudevan, Smitha; Gunlycke, Daniel

2011-03-01

Recently an extended line defect was observed composed of octagonal and pentagonal carbon rings embedded in a graphene sheet [Nat. Nanotech. 5, 326 (2010)]. We report results of studies we have made of this defect using both first-principles and semi-empirical methods. Two types of boundary-localized states arising from the defect are identified. The first (second) type has eigenstates with wavefunctions that are anti- symmetric (symmetric) with respect to a mirror plane that is perpendicular to the graphene sheet and passes through the line defect center line. The boundary-localized anti-symmetric states are shown to be intimately connected to the zigzag edge states of semi-infinite graphene. They exhibit little dispersion along the defect line and lie close to the Fermi level giving rise to a spontaneous spin polarization along the defect once electron-electron interactions are included at the level of a mean field approximation to a Hubbard Model. Within this approach, symmetry requires that the principal moments couple ferromagnetically both along and across the line defect leading to approximately 2/3 more up than down spin electrons per defect repeat unit. This work was supported by ONR, directly and through NRL.

Reassignment of oxygen-related defects in CdTe and CdSe

International Nuclear Information System (INIS)

Bastin, Dirk

2015-01-01

This thesis reassigns the O_T_e-V_C_d complex in CdTe and the O_S_e-V_C_d complex in CdSe to a sulfur-dioxygen complex SO_2*, and the O_C_d defect in CdSe to a V_C_dH_2 complex using Fourier transformed infrared absorption spectroscopy. The publications of the previous complexes were investigated by theoreticians who performed first-principle calculations of theses complexes. The theoreticians ruled out the assignments and proposed alternative defects, instead. The discrepancy between the experimentally obtained and theoretically proposed defects was the motivation of this work. Two local vibrational modes located at 1096.8 (ν_1) and 1108.3 cm"-"1 (ν_2) previously assigned to an O_T_e-V_C_d complex are detected in CdTe single crystals doped with CdSO_4 powder. Five weaker additional absorption lines accompanying ν_1 and ν_2 could be detected. The relative intensities of the absorption lines match a sulfur-dioxygen complex SO_2* having two configurations labeled ν_1 and ν_2. A binding energy difference of 0.5±0.1 meV between the two configurations and an energy barrier of 53±4 meV separating the two configurations are determined. Uniaxial stress applied to the crystal leads to a splitting of the absorption lines which corresponds to an orthorhombic and monoclinic symmetry for ν_1 and ν_2, respectively. In virgin and oxygen-doped CdSe single crystals, three local vibrational modes located at 1094.1 (γ_1), 1107.5 (γ_2), and 1126.3 cm"-"1 (γ_3) previously attributed to an O_S_e-V_C_d complex could be observed. The signals are accompanied by five weaker additional absorption features in their vicinity. The additional absorption lines are identified as isotope satellites of a sulfur-dioxygen complex SO_2* having three configurations γ_1, γ_2, and γ_3. IR absorption measurements with uniaxial stress applied to the CdSe crystal yield a monoclinic C_1_h symmetry for γ_1 and γ_2. The SO_2* complex is stable up to 600 C. This thesis assigns the ν-lines in

The development and application of composite complexity models and a relative complexity metric in a software maintenance environment

Science.gov (United States)

Hops, J. M.; Sherif, J. S.

1994-01-01

A great deal of effort is now being devoted to the study, analysis, prediction, and minimization of software maintenance expected cost, long before software is delivered to users or customers. It has been estimated that, on the average, the effort spent on software maintenance is as costly as the effort spent on all other software costs. Software design methods should be the starting point to aid in alleviating the problems of software maintenance complexity and high costs. Two aspects of maintenance deserve attention: (1) protocols for locating and rectifying defects, and for ensuring that noe new defects are introduced in the development phase of the software process; and (2) protocols for modification, enhancement, and upgrading. This article focuses primarily on the second aspect, the development of protocols to help increase the quality and reduce the costs associated with modifications, enhancements, and upgrades of existing software. This study developed parsimonious models and a relative complexity metric for complexity measurement of software that were used to rank the modules in the system relative to one another. Some success was achieved in using the models and the relative metric to identify maintenance-prone modules.

Current Strategies in Reconstruction of Maxillectomy Defects

Science.gov (United States)

Andrades, Patricio; Militsakh, Oleg; Hanasono, Matthew M.; Rieger, Jana; Rosenthal, Eben L.

2014-01-01

Objective To outline a contemporary review of defect classification and reconstructive options. Design Review article. Setting Tertiary care referral centers. Results Although prosthetic rehabilitation remains the standard of care in many institutions, the discomfort of wearing, removing, and cleaning a prosthesis; the inability to retain a prosthesis in large defects; and the frequent need for readjustments often limit the value of this cost-effective and successful method of restoring speech and mastication. However, flap reconstruction offers an option for many, although there is no agreement as to which techniques should be used for optimal reconstruction. Flap reconstruction also involves a longer recovery time with increased risk of surgical complications, has higher costs associated with the procedure, and requires access to a highly experienced surgeon. Conclusion The surgeon and reconstructive team must make individualized decisions based on the extent of the maxillectomy defect (eg, the resection of the infraorbital rim, the extent of palate excision, skin compromise) and the need for radiation therapy. PMID:21844415

A stereotactic system for guiding complex craniofacial reconstruction.

Science.gov (United States)

Fialkov, J A; Phillips, J H; Gruss, J S; Kassel, E E; Zuker, R M

1992-02-01

A stereotactic system has been designed to address the problem of achieving symmetry in complex and extensive craniofacial defects. Preliminary testing suggests that such a system, which allows for the intraoperative application of preoperative CT planning, will be useful in guiding the reconstruction of congenital or acquired bony time, is being used to investigate the correlation of intraoperative globe position following enophthalmos correction with long-term outcome, particularly as it relates to the size and location of the orbital defect, and the timing of the procedure.

dc-Hydrogen plasma induced defects in bulk n-Ge

Energy Technology Data Exchange (ETDEWEB)

Nyamhere, C., E-mail: cloud.nyamhere@nmmu.ac.za [Department of Physics, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031 (South Africa); Venter, A.; Murape, D.M. [Department of Physics, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031 (South Africa); Auret, F.D.; Coelho, S.M.M. [Department of Physics, University of the Pretoria, Lynnwood Road, Pretoria 0002 (South Africa); Botha, J.R. [Department of Physics, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031 (South Africa)

2012-08-01

Bulk antimony doped germanium (n-Ge) has been exposed to a dc-hydrogen plasma. Capacitance-voltage depth profiles revealed extensive near surface passivation of the shallow donors as evidenced by {approx}a 1.5 orders of magnitude reduction in the free carrier concentration up to depth of {approx}3.2 {mu}m. DLTS and Laplace-DLTS revealed a prominent electron trap 0.30 eV below the conduction (E{sub C} -0.30 eV). The concentration of this trap increased with plasma exposure time. The depth profile for this defect suggested a uniform distribution up to 1.2 {mu}m. Annealing studies show that this trap, attributed to a hydrogen-related complex, is stable up to 200 Degree-Sign C. Hole traps, or vacancy-antimony centers, common in this material after high energy particle irradiation, were not observed after plasma exposure, an indication that this process does not create Frenkel (V-I) pairs.

dc-Hydrogen plasma induced defects in bulk n-Ge

International Nuclear Information System (INIS)

Nyamhere, C.; Venter, A.; Murape, D.M.; Auret, F.D.; Coelho, S.M.M.; Botha, J.R.

2012-01-01

Bulk antimony doped germanium (n-Ge) has been exposed to a dc-hydrogen plasma. Capacitance-voltage depth profiles revealed extensive near surface passivation of the shallow donors as evidenced by ∼a 1.5 orders of magnitude reduction in the free carrier concentration up to depth of ∼3.2 μm. DLTS and Laplace-DLTS revealed a prominent electron trap 0.30 eV below the conduction (E C -0.30 eV). The concentration of this trap increased with plasma exposure time. The depth profile for this defect suggested a uniform distribution up to 1.2 μm. Annealing studies show that this trap, attributed to a hydrogen-related complex, is stable up to 200 °C. Hole traps, or vacancy-antimony centers, common in this material after high energy particle irradiation, were not observed after plasma exposure, an indication that this process does not create Frenkel (V-I) pairs.

Positron annihilation study of vacancy-type defects in fast-neutron-irradiated MgO·nAl2O3

International Nuclear Information System (INIS)

Rahman, Abu Zayed Mohammad Saliqur; Li, Zhuoxin; Cao, Xingzhong; Wang, Baoyi; Wei, Long; Xu, Qiu; Atobe, Kozo

2014-01-01

Highlights: •Detection of Al monovacancy by positron lifetime spectroscopy in fast neutron-irradiated MgO·nAl 2 O 3 (n=2). •Concentration of defects is also estimated for Al monovacancy. •O atom peak was observed by using coincidence Doppler broadening spectroscopy. -- Abstract: The positron lifetimes of fast-neutron-irradiated MgO·nAl 2 O 3 single crystals were measured to investigate the formation of cation vacancies. Al monovacancy was possibly observed in samples irradiated by fast neutrons at ultra-low temperatures. Additionally, vacancy-oxygen complex centers were possibly observed in samples irradiated at higher temperatures and fast neutron fluences. Coincidence Doppler broadening (CDB) spectra were measured to obtain information regarding the vicinity of vacancy-type defects. A peak at approximately 11 × 10 −3 m 0 c was observed, which may be due to the presence of oxygen atoms in the neighborhood of the vacancies

Optical excitation of Er centers in GaN epilayers grown by MOCVD

Science.gov (United States)

George, D. K.; Hawkins, M. D.; Jiang, H. X.; Lin, J. Y.; Zavada, J. M.; Vinh, N. Q.

2016-02-01

In this paper we present results of photoluminescence (PL), photoluminescence excitation (PLE), and time resolved PL spectroscopy of the 4I13/2 → 4I15/2 transition in Er optical centers in GaN epilayers grown by metal-organic chemical vapor deposition. Under resonance excitation via the higher-lying inner 4f shell transitions and band-to-band excitation of the semiconductor host, the PL and PLE spectra reveal an existence of two types of Er optical centers from isolated and the defect-related Er centers in GaN epilayers. These centers have different PL spectra, local defect environments, decay dynamics, and excitation cross-sections. The isolated Er optical center, which can be excited by either excitation mechanism, has the same decay dynamics, but possesses a much higher cross-section under band-to-band excitation. In contrast, the defect-related Er center can only be observed through band-to-band excitation but has the largest crosssection. Our results indicate pathways for efficient optical excitation of Er-doped GaN semiconductors.

N{sup +} ion-implantation-induced defects in ZnO studied with a slow positron beam

Energy Technology Data Exchange (ETDEWEB)

Chen, Z Q [Japan Atomic Energy Research Institute, 1233 Watanuki, Takasaki, Gunma 370-1292, Japan (Japan); Sekiguchi, T [Nanomaterials Laboratory, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Yuan, X L [Nanomaterials Laboratory, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Maekawa, M [Japan Atomic Energy Research Institute, 1233 Watanuki, Takasaki, Gunma 370-1292, Japan (Japan); Kawasuso, A [Japan Atomic Energy Research Institute, 1233 Watanuki, Takasaki, Gunma 370-1292, Japan (Japan)

2004-01-21

Undoped ZnO single crystals were implanted with multiple-energy N{sup +} ions ranging from 50 to 380 keV with doses from 10{sup 12} to 10{sup 14} cm{sup -2}. Positron annihilation measurements show that vacancy defects are introduced in the implanted layers. The concentration of the vacancy defects increases with increasing ion dose. The annealing behaviour of the defects can be divided into four stages, which correspond to the formation and recovery of large vacancy clusters and the formation and disappearance of vacancy-impurity complexes, respectively. All the implantation-induced defects are removed by annealing at 1200 deg. C. Cathodoluminescence measurements show that the ion-implantation-induced defects act as nonradiative recombination centres to suppress the ultraviolet (UV) emission. After annealing, these defects disappear gradually and the UV emission reappears, which coincides with positron annihilation measurements. Hall measurements reveal that after N{sup +} implantation, the ZnO layer still shows n-type conductivity.

Phase defects and spatiotemporal disorder in traveling-wave convection patterns

International Nuclear Information System (INIS)

La Porta, A.; Surko, C.M.

1997-01-01

Spatiotemporal disorder is studied in traveling-wave convection in ethanol-water mixtures. Spectral measures of disorder, linear correlation functions, and mutual information are used to characterize the patterns, and are found to give a weak indication of the level of disorder. The calculation of the complex order parameter for experimental patterns is described. It is found that the ordering of the patterns is accompanied by a dramatic change in the topological structure of the order parameter. Specific arrangements of defects are found to be associated with the elements of traveling-wave patterns, and the net charge and total number of defects is introduced as a measure of disorder in the patterns. The coarsening of the patterns is marked by an accumulation of net charge and a dramatic decrease in the number of defects. The physical significance of the defects is discussed, and it is shown that the phase velocity of the waves is lower in the vicinity of the defects. The defect-defect correlation functions are calculated for the convection patterns. It is shown that the ordering of the patterns is closely related to the apparent defect-defect interactions. copyright 1997 The American Physical Society

Limb-body wall complex: Prenatal sonographic findings versus autopsy findings

International Nuclear Information System (INIS)

Song, Mi Jin; Cho, Jeong Yeon; Lee, Young Ho

2001-01-01

To evaluate prenatal ultrasonographic findings of limb-body wall complex and to correlate them with autopsy findings. From October 1995 to June 2000, a retrospectively review of prenatal ultrasonography (US) of 11 patients with pathologically proven limb-body wall complex was done. US findings were then compared with autopsy findings. Prenatal ultrasonography revealed thoraco-abdominoschists (n=7.64%), kyphoscoliosis (n=7.64%), cranial defect (n=5.45%), limb defect (n=4.36%), facial defect (n=1.10%), amniotic band (n=5.45%), and umbilical cord anomaly (n=3.27%). Meanwhile, autopsy findings showed thoraco-abdominoschisis (n=8.72%), limb defect (n=7.64%), facial defect (n=7.64%), kyphoscoliosis (n=5.45%), cranial defect (n=5.45%), amniotic band (n=5.45%) and umbilical cord anomaly (n=4.36%). The most common ultrasonography features of limb-body wall complex were thoraco-abdominoschisis and kyphoscoliosis while the thoraco-abdominoschisis and limb defects were the most frequent findings at autopsy.

Multiscale crystal defect dynamics: A coarse-grained lattice defect model based on crystal microstructure

Science.gov (United States)

Lyu, Dandan; Li, Shaofan

2017-10-01

Crystal defects have microstructure, and this microstructure should be related to the microstructure of the original crystal. Hence each type of crystals may have similar defects due to the same failure mechanism originated from the same microstructure, if they are under the same loading conditions. In this work, we propose a multiscale crystal defect dynamics (MCDD) model that models defects by considering its intrinsic microstructure derived from the microstructure or material genome of the original perfect crystal. The main novelties of present work are: (1) the discrete exterior calculus and algebraic topology theory are used to construct a scale-up (coarse-grained) dual lattice model for crystal defects, which may represent all possible defect modes inside a crystal; (2) a higher order Cauchy-Born rule (up to the fourth order) is adopted to construct atomistic-informed constitutive relations for various defect process zones, and (3) an hierarchical strain gradient theory based finite element formulation is developed to support an hierarchical multiscale cohesive (process) zone model for various defects in a unified formulation. The efficiency of MCDD computational algorithm allows us to simulate dynamic defect evolution at large scale while taking into account atomistic interaction. The MCDD model has been validated by comparing of the results of MCDD simulations with that of molecular dynamics (MD) in the cases of nanoindentation and uniaxial tension. Numerical simulations have shown that MCDD model can predict dislocation nucleation induced instability and inelastic deformation, and thus it may provide an alternative solution to study crystal plasticity.

Excitation mechanisms of Er optical centers in GaN epilayers

International Nuclear Information System (INIS)

George, D. K.; Hawkins, M. D.; McLaren, M.; Vinh, N. Q.; Jiang, H. X.; Lin, J. Y.; Zavada, J. M.

2015-01-01

We report direct evidence of two mechanisms responsible for the excitation of optically active Er 3+ ions in GaN epilayers grown by metal-organic chemical vapor deposition. These mechanisms, resonant excitation via the higher-lying inner 4f shell transitions and band-to-band excitation of the semiconductor host, lead to narrow emission lines from isolated and the defect-related Er optical centers. However, these centers have different photoluminescence spectra, local defect environments, decay dynamics, and excitation cross sections. The photoluminescence at 1.54 μm from the isolated Er optical center which can be excited by either mechanism has the same decay dynamics, but possesses a much higher excitation cross-section under band-to-band excitation. In contrast, the photoluminescence at 1.54 μm from the defect-related Er optical center can only be observed through band-to-band excitation but has the largest excitation cross-section. These results explain the difficulty in achieving gain in Er doped GaN and indicate approaches for realization of optical amplification, and possibly lasing, at room temperature

Marshak Lectureship: Vibrational properties of isolated color centers in diamond

Science.gov (United States)

Alkauskas, Audrius

In this talk we review our recent work on first-principles calculations of vibrational properties of isolated defect spin qubits and single photon emitters in diamond. These properties include local vibrational spectra, luminescence lineshapes, and electron-phonon coupling. They are key in understanding physical mechanisms behind spin-selective optical initialization and read-out, quantum efficiency of single-photon emitters, as well as in the experimental identification of as yet unknown centers. We first present the methodology to calculate and analyze vibrational properties of effectively isolated defect centers. We then apply the methodology to the nitrogen-vacancy and the silicon-vacancy centers in diamond. First-principles calculations yield important new insights about these important defects. Work performed in collaboration with M. W. Doherty, A. Gali, E. Londero, L. Razinkovas, and C. G. Van de Walle. Supported by the Research Council of Lithuania (Grant M-ERA.NET-1/2015).

Photochemistry and reactions of OH- defects and F centers in alkali halides

International Nuclear Information System (INIS)

Morato, S.P.; Luety, F.

1978-01-01

Aditively colored KCl:OH - crystals showed under a combined UV and VIS irradiation, a nearly complete and irreversible destruction of all F centers and visible absorption in the crystal. Only upon heating the crystal above 650 0 C the F center coloration becomes partially restored. The photodissociation of the OH - (under UV light) together with the photoionization of the F center (under VIS light) produces a not effects where all the F centers are converted into U centers. These photoreactions produces high contrast visible images that are completely stable under light at RT. Besides the optical information storage aspect of this effect these photoreaction s can also be used for controlled production of Usub(A) centers if the crystal also contains a foreign metallic impurity such a Na + ion [pt

Modeling local structure using crystal field and spin Hamiltonian parameters: the tetragonal FeK3+-OI2- defect center in KTaO3 crystal

International Nuclear Information System (INIS)

Gnutek, P; Rudowicz, C; Yang, Z Y

2009-01-01

The local structure and the spin Hamiltonian (SH) parameters, including the zero-field-splitting (ZFS) parameters D and (a+2F/3), and the Zeeman g factors g || and g perpendicular , are theoretically investigated for the Fe K 3+ -O I 2- center in KTaO 3 crystal. The microscopic SH (MSH) parameters are modeled within the framework of the crystal field (CF) theory employing the CF analysis (CFA) package, which also incorporates the MSH modules. Our approach takes into account the spin-orbit interaction as well as the spin-spin and spin-other-orbit interactions omitted in previous studies. The superposition model (SPM) calculations are carried out to provide input CF parameters for the CFA/MSH package. The combined SPM-CFA/MSH approach is used to consider various structural models for the Fe K 3+ -O I 2- defect center in KTaO 3 . This modeling reveals that the off-center displacement of the Fe 3+ ions, Δ 1 (Fe 3+ ), combined with an inward relaxation of the nearest oxygen ligands, Δ 2 (O 2- ), and the existence of the interstitial oxygen O I 2- give rise to a strong tetragonal crystal field. This finding may explain the large ZFS experimentally observed for the Fe K 3+ -O I 2- center in KTaO 3 . Matching the theoretical MSH predictions with the available structural data as well as electron magnetic resonance (EMR) and optical spectroscopy data enables predicting reasonable ranges of values of Δ 1 (Fe 3+ ) and Δ 2 (O 2- ) as well as the possible location of O I 2- ligands around Fe 3+ ions in KTaO 3 . The defect structure model obtained using the SPM-CFA/MSH approach reproduces very well the ranges of the experimental SH parameters D, g || and g perpendicular and importantly yields not only the correct magnitude of D but also the sign, unlike previous studies. More reliable predictions may be achieved when experimental data on (a+2F/3) and/or crystal field energy levels become available. Comparison of our results with those arising from alternative models existing

F-type centers in neutron-irradiated AIN

International Nuclear Information System (INIS)

Atobe, Kozo; Honda, Makoto; Fukuoka, Noboru; Okada, Moritami; Nakagawa, Masuo.

1990-01-01

The production of point defects by neutron irradiation and thermal decay in sintered AIN polycrystal are investigated. The absorption band at 370 nm is observed after reactor neutron irradiation to a dose of 10 16 n/cm 2 (E > 0.1 MeV). The defect corresponding to the band is tentatively assigned as an F-type center from the optical absorption and electron spin resonance. (author)

Antigravity from a spacetime defect

OpenAIRE

Klinkhamer, F. R.; Queiruga, J. M.

2018-01-01

We argue that there may exist spacetime defects embedded in Minkowski spacetime, which have negative active gravitational mass. One such spacetime defect then repels a test particle, corresponding to what may be called "antigravity."

Radiation color and electron-hole centers of serpentines

International Nuclear Information System (INIS)

Lyutoev, V.P.; Yukhtanov, P.P.

1999-01-01

Radiation-induced coloring of serpentine (Mg 3 [Si 2 O 5 ](OH) 4 ), gamma radiation dose being 30 Mrad, is studied by the ESR and absorption spectroscopy methods. It is ascertained that ionizing radiation gives rise to formation of radiation centers on the mineral basic structural elements. paramagnetic centers and coloring centers, relating to radiation centers, stem from the same type of defects - O - oxygen centers, formed as a result of radiation-induced break of OH-bonds [ru

Defects and defect processes in nonmetallic solids

CERN Document Server

Hayes, W

2004-01-01

This extensive survey covers defects in nonmetals, emphasizing point defects and point-defect processes. It encompasses electronic, vibrational, and optical properties of defective solids, plus dislocations and grain boundaries. 1985 edition.

Energetics of intrinsic point defects in uranium dioxide from electronic-structure calculations

International Nuclear Information System (INIS)

Nerikar, Pankaj; Watanabe, Taku; Tulenko, James S.; Phillpot, Simon R.; Sinnott, Susan B.

2009-01-01

The stability range of intrinsic point defects in uranium dioxide is determined as a function of temperature, oxygen partial pressure, and non-stoichiometry. The computational approach integrates high accuracy ab initio electronic-structure calculations and thermodynamic analysis supported by experimental data. In particular, the density functional theory calculations are performed at the level of the spin polarized, generalized gradient approximation and includes the Hubbard U term; as a result they predict the correct anti-ferromagnetic insulating ground state of uranium oxide. The thermodynamic calculations enable the effects of system temperature and partial pressure of oxygen on defect formation energy to be determined. The predicted equilibrium properties and defect formation energies for neutral defect complexes match trends in the experimental literature quite well. In contrast, the predicted values for charged complexes are lower than the measured values. The calculations predict that the formation of oxygen interstitials becomes increasingly difficult as higher temperatures and reducing conditions are approached

Ab initio theory of the N2V defect in diamond for quantum memory implementation

Science.gov (United States)

Udvarhelyi, Péter; Thiering, Gergő; Londero, Elisa; Gali, Adam

2017-10-01

The N2V defect in diamond is characterized by means of ab initio methods relying on density functional theory calculated parameters of a Hubbard model Hamiltonian. It is shown that this approach appropriately describes the energy levels of correlated excited states induced by this defect. By determining its critical magneto-optical parameters, we propose to realize a long-living quantum memory by N2V defect, i.e., H 3 color center in diamond.

Reassignment of oxygen-related defects in CdTe and CdSe

Energy Technology Data Exchange (ETDEWEB)

Bastin, Dirk

2015-05-22

This thesis reassigns the O{sub Te}-V{sub Cd} complex in CdTe and the O{sub Se}-V{sub Cd} complex in CdSe to a sulfur-dioxygen complex SO{sub 2}*, and the O{sub Cd} defect in CdSe to a V{sub Cd}H{sub 2} complex using Fourier transformed infrared absorption spectroscopy. The publications of the previous complexes were investigated by theoreticians who performed first-principle calculations of theses complexes. The theoreticians ruled out the assignments and proposed alternative defects, instead. The discrepancy between the experimentally obtained and theoretically proposed defects was the motivation of this work. Two local vibrational modes located at 1096.8 (ν{sub 1}) and 1108.3 cm{sup -1} (ν{sub 2}) previously assigned to an O{sub Te}-V{sub Cd} complex are detected in CdTe single crystals doped with CdSO{sub 4} powder. Five weaker additional absorption lines accompanying ν{sub 1} and ν{sub 2} could be detected. The relative intensities of the absorption lines match a sulfur-dioxygen complex SO{sub 2}* having two configurations labeled ν{sub 1} and ν{sub 2}. A binding energy difference of 0.5±0.1 meV between the two configurations and an energy barrier of 53±4 meV separating the two configurations are determined. Uniaxial stress applied to the crystal leads to a splitting of the absorption lines which corresponds to an orthorhombic and monoclinic symmetry for ν{sub 1} and ν{sub 2}, respectively. In virgin and oxygen-doped CdSe single crystals, three local vibrational modes located at 1094.1 (γ{sub 1}), 1107.5 (γ{sub 2}), and 1126.3 cm{sup -1} (γ{sub 3}) previously attributed to an O{sub Se}-V{sub Cd} complex could be observed. The signals are accompanied by five weaker additional absorption features in their vicinity. The additional absorption lines are identified as isotope satellites of a sulfur-dioxygen complex SO{sub 2}* having three configurations γ{sub 1}, γ{sub 2}, and γ{sub 3}. IR absorption measurements with uniaxial stress applied to the

The quantitative evaluation of complex defect signals from eddy current testings with multi-frequency methods

International Nuclear Information System (INIS)

Naegele, W.

1982-01-01

The usual formulation of multi-frequency eddy current signals of large defects by linearized impedance diagrams may lead to misinterpretations. Here a developement of the linear superposition principle is proposed, which takes into account also the curvature of the impedance diagrams thus allowing to identify even large defects in an unambiguous way. (orig.) [de

Defect evolution in a Ni−Mo−Cr−Fe alloy subjected to high-dose Kr ion irradiation at elevated temperature

Energy Technology Data Exchange (ETDEWEB)

Reyes, Massey de los [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, 2234 (Australia); Nuclear Fuel Cycle Royal Commission (NFCRC), 50 Grenfell Street Adelaide South Australia, 5000 (Australia); Voskoboinikov, Roman [The National Research Centre ‘Kurchatov Institute’, Kurchatov Sq 1, Moscow 123182 (Russian Federation); Kirk, Marquis A. [Nuclear Engineering Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Huang, Hefei [Shanghai Institute of Applied Physics, Chinese Academy of Science (CAS), 2019 Jialuo Road, Jiading District, Shanghai 201800 (China); Lumpkin, Greg [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, 2234 (Australia); Bhattacharyya, Dhriti, E-mail: dhriti.bhattacharyya@ansto.gov.au [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, 2234 (Australia)

2016-06-15

A candidate Ni−Mo−Cr−Fe alloy (GH3535) for application as a structural material in a molten salt nuclear reactor was irradiated with 1 MeV Kr{sup 2+} ions (723 K, max dose of 100 dpa) at the IVEM-Tandem facility. The evolution of defects like dislocation loops and vacancy- and self-interstitial clusters was examined in-situ. For obtaining a deeper insight into the true nature of these defects, the irradiated sample was further analysed under a TEM post-facto. The results show that there is a range of different types of defects formed under irradiation. Interaction of radiation defects with each other and with pre-existing defects, e.g., linear dislocations, leads to the formation of complex microstructures. Molecular dynamics simulations used to obtain a greater understanding of these defect transformations showed that the interaction between linear dislocations and radiation induced dislocation loops could form faulted structures that explain the fringed contrast of these defects observed in TEM.

NMR studies of defects created by irradiation in metals

International Nuclear Information System (INIS)

Minier, M.; Minier, C.

1983-06-01

Nuclear Magnetic Resonance has been rarely used to study point defects created by irradiation in metals. Information obtained in this field using N.M.R. are shown. Some results are also described: characterization of migrating defects in electron irradiated copper; mobility of the complex interstitial-impurity in Al with 150 ppm of chromium; interstitial structure in irradiated aluminum and autodiffusion in metals [fr

Microvascular free flaps in the management of war wounds with tissue defects

Directory of Open Access Journals (Sweden)

Kozarski Jefta

2003-01-01

Full Text Available Background. War wounds caused by modern infantry weapons or explosive devices are very often associated with the defects of soft and bone tissue. According to their structure, tissue defects can be simple or complex. In accordance with war surgical doctrine, at the Clinic for Plastic Surgery and Burns of the Military Medical Academy, free flaps were used in the treatment of 108 patients with large tissue defects. With the aim of closing war wounds, covering deep structures, or making the preconditions for reconstruction of deep structures, free flaps were applied in primary, delayed, or secondary term. The main criteria for using free flaps were general condition of the wounded, extent, location, and structure of tissue defects. The aim was also to point out the advantages and disadvantages of the application of free flaps in the treatment of war wounds. Methods. One hundred and eleven microvascular free flaps were applied, both simple and complex, for closing the war wounds with extensive tissue defects. The main criteria for the application of free flaps were: general condition of the wounded, size, localization, and structure of tissue defects. For the extensive defects of the tissue, as well as for severely contaminated wounds latissimus dorsi free flaps were used. For tissue defects of distal parts of the lower extremities, scapular free flaps were preferred. While using free tissue transfer for recompensation of bone defects, free vascularized fibular grafts were applied, and in skin and bone defects complex free osteoseptocutaneous fibular, free osteoseptocutaneous radial forearm, and free skin-bone scapular flaps were used. Results. After free flap transfer 16 (14,4% revisions were performed, and after 8 unsuccessful revisions another free flaps were utilized in 3 (37,5% patients, and cross leg flaps in 5 (62,5% patients. Conclusion. The treatment of war wounds with large tissue defects by the application of free microvascular flaps

Public health approach to birth defects: the Argentine experience.

Science.gov (United States)

Bidondo, María Paz; Groisman, Boris; Barbero, Pablo; Liascovich, Rosa

2015-04-01

Birth defects are a global problem, but their impact is particularly severe in low and middle income countries, where the conditions for prevention, treatment, and rehabilitation are more critical. The epidemiological transition in the infant mortality causes, and the concern of the community and the mass media about the teratogenic risk of environmental pollutants, has made health authorities aware of the importance of birth defects in Argentina. The objective of this paper is to outline those actions specifically taken in Argentina aimed at the prevention of birth defects at a national level. Firstly, we focus on birth defects in Argentina on a general basis, and then we present different laws and actions taken in terms of surveillance and public health programs, primary, secondary, and tertiary prevention. Finally, we present the Teratology Information Service "Fetal Health Line", and the genetic services organization and health professionals training by the National Center of Medical Genetics and the National Program of Genetics Network. In conclusion, in the country, several programs focus on different approaches to the problem, and the challenge is to coordinate the teamwork between them. Finally, we list tips to address birth defects from the public health perspective.

Defect studies in electron-irradiated ZnO and GaN

International Nuclear Information System (INIS)

Tuomisto, F.; Look, D.C.; Farlow, G.C.

2007-01-01

We present experimental results obtained with positron annihilation spectroscopy in room-temperature electron-irradiated n-type ZnO and GaN. The cation vacancies act as important compensating centers in 2 MeV electron-irradiated samples, even though their introduction rates are different by 2 orders of magnitude. In addition, negatively charged non-open volume defects that also compensate the n-type conductivity are produced together with the cation vacancies at similar introduction rates. The low introduction rates of compensating defects in ZnO demonstrate the radiation hardness of the material. Isochronal thermal annealings were performed to study the dynamics of the irradiation-induced defects. In 2 MeV electron-irradiated ZnO, all the defects introduced in the irradiation disappear already at 600 K, while 1100 K is needed in GaN. Several separate annealing stages of the defects are observed in both materials, the first at 400 K

Defect studies in electron-irradiated ZnO and GaN

Energy Technology Data Exchange (ETDEWEB)

Tuomisto, F. [Laboratory of Physics, Helsinki University of Technology, 02015 TKK Espoo (Finland)], E-mail: filip.tuomisto@tkk.fi; Look, D.C. [Semiconductor Research Center, Wright State University, Dayton, OH 45435 (United States); Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, OH 45433 (United States); Farlow, G.C. [Physics Department, Wright State University, Dayton, OH 45435 (United States)

2007-12-15

We present experimental results obtained with positron annihilation spectroscopy in room-temperature electron-irradiated n-type ZnO and GaN. The cation vacancies act as important compensating centers in 2 MeV electron-irradiated samples, even though their introduction rates are different by 2 orders of magnitude. In addition, negatively charged non-open volume defects that also compensate the n-type conductivity are produced together with the cation vacancies at similar introduction rates. The low introduction rates of compensating defects in ZnO demonstrate the radiation hardness of the material. Isochronal thermal annealings were performed to study the dynamics of the irradiation-induced defects. In 2 MeV electron-irradiated ZnO, all the defects introduced in the irradiation disappear already at 600 K, while 1100 K is needed in GaN. Several separate annealing stages of the defects are observed in both materials, the first at 400 K.

Electron paramagnetic resonance study on the ionizing radiation induced defects of the tooth enamel hydroxyapatite; Estudo por ressonancia paramagnetica eletronica de defeitos induzidos pelas radiacoes ionizantes na hidroxiapatita do esmalte dentario

Energy Technology Data Exchange (ETDEWEB)

Oliveira, Liana Macedo de

1995-01-01

Hydroxyapatite is the main constituent of calcified tissues. Defects induced by ionizing radiations in this biomineral can present high stability and then, these are used as biological markers in radiological accidents, irradiated food identifying and geological and archaeological dating. In this work, paramagnetic centers induced on the enamel of the teeth by environmental ionizing radiation, are investigated by electron paramagnetic resonance (EPR). Decay thermal kinetic presents high complexity and shows the formation of different electron ligation energy centers and structures 65 refs., 40 figs., 5 tabs.

Promotion of mitochondrial membrane complex assembly by a proteolytically inactive yeast Lon

NARCIS (Netherlands)

Rep, M; van Dijl, J M; Suda, K; Schatz, G; Grivell, L A; Suzuki, C K

1996-01-01

Afg3p and Rca1p are adenosine triphosphate (ATP)-dependent metalloproteases in yeast mitochondria. Cells lacking both proteins exhibit defects in respiration-dependent growth, degradation of mitochondrially synthesized proteins, and assembly of inner-membrane complexes. Defects in growth and protein

Structural defects in monocrystalline silicon: from radiation ones to growing and technological

International Nuclear Information System (INIS)

Gerasimenko, N.N.; Pavlyuchenko, M.N.; Dzhamanbalin, K.K.

2001-01-01

The systematical review of properties and conditions of radiation structures in monocrystalline silicon including own defects (elementary and complex, disordered fields) as well as defect-impurity formations is presented. The most typical examples of principle effects influence of known defects on radiation-induced processes (phase transformations, diffusion and heteration and others are considered. Experimental facts and models of silicon radiation amorphization have been analyzed in comparison of state of the radiation amorphization radiation problem of metals and alloys. The up-to-date status of the problem of the radiation defects physics are discussed, including end-of-range -, n+-, rod-like- defects. The phenomenon self-organization in crystals with defects has been considered. The examples of directed using radiation defects merged in independent trend - defects engineering - are given

Study of defects in radiation tolerant semiconductor SiC

Energy Technology Data Exchange (ETDEWEB)

Itoh, Hisayoshi; Kawasuso, Atsuo; Ohshima, Takeshi; Yoshikawa, Masahito; Nashiyama, Isamu [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment; Okumura, Hajime; Yoshida, Sadafumi

1997-03-01

Electron spin resonance (ESR) was used to study defects introduced in n-type 6H-SiC by 3 MeV electron irradiation. Two ESR signals labeled A and B related to radiation induced defects were observed. An ESR signal B can be explained by a fine interaction with an effective spin S=1. The g and D tensors of the signal B were found to be axially symmetric along the c-axis. The principal values of the g were obtained to be g parallel = 2.003 and g perpendicular = 2.008, and the absolute value of the D was 3.96x10{sup -2} cm{sup -1} at 100 K for this signal. It was also found that the value |D| decreased with increasing temperature. Isochronal annealing showed that the A and B centers have annealing stages of {approx_equal}200degC and {approx_equal}800degC, respectively. Tentative structural models are discussed for these ESR centers. (author)

Birth Defects

Science.gov (United States)

A birth defect is a problem that happens while a baby is developing in the mother's body. Most birth defects happen during the first 3 months of ... in the United States is born with a birth defect. A birth defect may affect how the ...

Near-infrared 808 nm light boosts complex IV-dependent respiration and rescues a Parkinson-related pink1 model.

Directory of Open Access Journals (Sweden)

Melissa Vos

Full Text Available Mitochondrial electron transport chain (ETC defects are observed in Parkinson's disease (PD patients and in PD fly- and mouse-models; however it remains to be tested if acute improvement of ETC function alleviates PD-relevant defects. We tested the hypothesis that 808 nm infrared light that effectively penetrates tissues rescues pink1 mutants. We show that irradiating isolated fly or mouse mitochondria with 808 nm light that is absorbed by ETC-Complex IV acutely improves Complex IV-dependent oxygen consumption and ATP production, a feature that is wavelength-specific. Irradiating Drosophila pink1 mutants using a single dose of 808 nm light results in a rescue of major systemic and mitochondrial defects. Time-course experiments indicate mitochondrial membrane potential defects are rescued prior to mitochondrial morphological defects, also in dopaminergic neurons, suggesting mitochondrial functional defects precede mitochondrial swelling. Thus, our data indicate that improvement of mitochondrial function using infrared light stimulation is a viable strategy to alleviate pink1-related defects.

Improving reticle defect disposition via fully automated lithography simulation

Science.gov (United States)

Mann, Raunak; Goodman, Eliot; Lao, Keith; Ha, Steven; Vacca, Anthony; Fiekowsky, Peter; Fiekowsky, Dan

2016-03-01

Most advanced wafer fabs have embraced complex pattern decoration, which creates numerous challenges during in-fab reticle qualification. These optical proximity correction (OPC) techniques create assist features that tend to be very close in size and shape to the main patterns as seen in Figure 1. A small defect on an assist feature will most likely have little or no impact on the fidelity of the wafer image, whereas the same defect on a main feature could significantly decrease device functionality. In order to properly disposition these defects, reticle inspection technicians need an efficient method that automatically separates main from assist features and predicts the resulting defect impact on the wafer image. Analysis System (ADAS) defect simulation system[1]. Up until now, using ADAS simulation was limited to engineers due to the complexity of the settings that need to be manually entered in order to create an accurate result. A single error in entering one of these values can cause erroneous results, therefore full automation is necessary. In this study, we propose a new method where all needed simulation parameters are automatically loaded into ADAS. This is accomplished in two parts. First we have created a scanner parameter database that is automatically identified from mask product and level names. Second, we automatically determine the appropriate simulation printability threshold by using a new reference image (provided by the inspection tool) that contains a known measured value of the reticle critical dimension (CD). This new method automatically loads the correct scanner conditions, sets the appropriate simulation threshold, and automatically measures the percentage of CD change caused by the defect. This streamlines qualification and reduces the number of reticles being put on hold, waiting for engineer review. We also present data showing the consistency and reliability of the new method, along with the impact on the efficiency of in

Size-controlled fluorescent nanodiamonds: A facile method of fabrication and color-center counting

KAUST Repository

Mahfouz, Remi

2013-01-01

We present a facile method for the production of fluorescent diamond nanocrystals (DNCs) of different sizes and efficiently quantify the concentration of emitting defect color centers (DCCs) of each DNC size. We prepared the DNCs by ball-milling commercially available micrometer-sized synthetic (high pressure, high temperature (HPHT)) diamonds and then separated the as-produced DNCs by density gradient ultracentrifugation (DGU) into size-controlled fractions. A protocol to enhance the uniformity of the nitrogen-vacancy (NV) centers in the diamonds was devised by depositing the DNCs as a dense monolayer on amino-silanized silicon substrates and then subjecting the monolayer to He+ beam irradiation. Using a standard confocal setup, we analyzed the average number of NV centers per crystal, and obtained a quantitative relationship between the DNC particle size and the NV number per crystal. This relationship was in good agreement with results from previous studies that used more elaborate setups. Our findings suggest that nanocrystal size separation by DGU may be used to control the number of defects per nanocrystal. The efficient approaches described herein to control and quantify DCCs are valuable to researchers as they explore applications for color centers and new strategies to create them. © 2013 The Royal Society of Chemistry.

Vision Algorithms Catch Defects in Screen Displays

Science.gov (United States)

2014-01-01

Andrew Watson, a senior scientist at Ames Research Center, developed a tool called the Spatial Standard Observer (SSO), which models human vision for use in robotic applications. Redmond, Washington-based Radiant Zemax LLC licensed the technology from NASA and combined it with its imaging colorimeter system, creating a powerful tool that high-volume manufacturers of flat-panel displays use to catch defects in screens.

Numerical simulation of a metal corrosion for a point defect for a organic protection layer

International Nuclear Information System (INIS)

Vautrin-Ul, Ch.; Chausse, A.; Stafiej, J.; Badiali, J.P.

2005-01-01

The safety of radioactive wastes disposal requires a big knowledge on their aging facing a corrosive environment. The corrosion is a complex phenomenon which implies many processes bound to the physic and the chemistry of the system. This approach proposes, from a little number of simple processes, numerical simulation which will define theses complex phenomenon. The presented model is a 2 dimension model at a mesoscopic scale and based on cellular automates. It allows the simulation of a metal evolution, protected by a polymer layer and in contact at one point with a corrosive media at a defect of the layer. (A.L.B.)

TorsinA dysfunction causes persistent neuronal nuclear pore defects.

Science.gov (United States)

Pappas, Samuel S; Liang, Chun-Chi; Kim, Sumin; Rivera, CheyAnne O; Dauer, William T

2018-02-01

A critical challenge to deciphering the pathophysiology of neurodevelopmental disease is identifying which of the myriad abnormalities that emerge during CNS maturation persist to contribute to long-term brain dysfunction. Childhood-onset dystonia caused by a loss-of-function mutation in the AAA+ protein torsinA exemplifies this challenge. Neurons lacking torsinA develop transient nuclear envelope (NE) malformations during CNS maturation, but no NE defects are described in mature torsinA null neurons. We find that during postnatal CNS maturation torsinA null neurons develop mislocalized and dysfunctional nuclear pore complexes (NPC) that lack NUP358, normally added late in NPC biogenesis. SUN1, a torsinA-related molecule implicated in interphase NPC biogenesis, also exhibits localization abnormalities. Whereas SUN1 and associated nuclear membrane abnormalities resolve in juvenile mice, NPC defects persist into adulthood. These findings support a role for torsinA function in NPC biogenesis during neuronal maturation and implicate altered NPC function in dystonia pathophysiology. © The Author(s) 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Stability and electronic structure of iron nanoparticle anchored on defective hexagonal boron nitrogen nanosheet: A first-principle study

International Nuclear Information System (INIS)

Lin, Sen; Huang, Jing; Ye, Xinxin

2014-01-01

Highlights: • Fe 13 nanoparticle strongly interacts with the monovacancy of h-BN nanosheet. • Significant charges are transferred from Fe 13 to the defective h-BN nanosheet. • The upshift of d-band center makes the surface Fe atoms of supported Fe 13 with higher reactivity. - Abstract: By first-principle methods, we investigate the stability and electronic structures of Fe 13 nanoparticles anchored on hexagonal boron nitrogen nanosheets (h-BNNSs) with monovacancy defect sites. It is found that the defect sites such as boron and nitrogen vacancy significantly increase the adsorption energies of Fe 13 , suggesting that the supported Fe 13 nanoparticles should be very stable against sintering at high temperatures. From the calculated density of states, we testify that the strong interaction is attributed to the coupling between the 3d orbitals of Fe atoms with the sp 2 dangling bonds at the defect sites. The Bader charge and differential charge density analyses reveal that there is significant charge redistribution at the interface between Fe 13 and the substrates, leading to positive charges located on most of the Fe atoms. Additionally, our results show that the strong binding of the nanoparticle results in the upshift of d-band center of Fe 13 toward the Fermi level, thus making the surface Fe atoms with higher reactivity. This work gives a detailed understanding the interaction between Fe 13 nanoparticle and defective h-BNNS and will provide helpful instructions in the design and synthesis of supported Fe-based catalysts in heterogeneous catalysis

Low-temperature annealing of radiation defects in electron-irradiated gallium phosphide

International Nuclear Information System (INIS)

Kolb, A.A.; Megela, I.G.; Buturlakin, A.P.; Goyer, D.B.

1990-01-01

The isochronal annealing of radiation defects in high-energy electron irradiated n-GaP monocrystals within the 77 to 300 K range has been investigated by optical and electrical techniques. The changes in conductance and charge carrier mobility as functions of annealing temperature as well as the variation of optical absorption spectra of GaP under irradiation and annealing provide evidence that most of radiation defects are likely secondary complexes of defects

First-Principles Investigations of Defects in Minerals

Science.gov (United States)

Verma, Ashok K.

2011-07-01

The ideal crystal has an infinite 3-dimensional repetition of identical units which may be atoms or molecules. But real crystals are limited in size and they have disorder in stacking which as called defects. Basically three types of defects exist in solids: 1) point defects, 2) line defects, and 3) surface defects. Common point defects are vacant lattice sites, interstitial atoms and impurities and these are known to influence strongly many solid-state transport properties such as diffusion, electrical conduction, creep, etc. In thermal equilibrium point defects concentrations are determined by their formation enthalpies and their movement by their migration barriers. Line and surface defects are though absent from the ideal crystal in thermal equilibrium due to higher energy costs but they are invariably present in all real crystals. Line defects include edge-, screw- and mixed-dislocations and their presence is essential in explaining the mechanical strength and deformation of real crystals. Surface defects may arise at the boundary between two grains, or small crystals, within a larger crystal. A wide variety of grain boundaries can form in a polycrystal depending on factors such growth conditions and thermal treatment. In this talk we will present our first-principles density functional theory based defect studies of SiO2 polymorphs (stishovite, CaCl2-, α-PbO2-, and pyrite-type), Mg2SiO4 polymorphs (forsterite, wadsleyite and ringwoodite) and MgO [1-3]. Briefly, several native point defects including vacancies, interstitials, and their complexes were studied in silica polymorphs upto 200 GPa. Their values increase by a factor of 2 over the entire pressure range studied with large differences in some cases between different phases. The Schottky defects are energetically most favorable at zero pressure whereas O-Frenkel pairs become systematically more favorable at pressures higher than 20 GPa. The geometric and electronic structures of defects and migrating

Surgical removal of atrial septal defect occlusion device and mitral valve replacement in a 39-year-old female patient with infective endocarditis

Directory of Open Access Journals (Sweden)

A S Zotov

2018-02-01

Full Text Available Atrial septal defects represent the second most frequent congenital heart disease after ventricular septal defects. Transcatheter closure of an atrial septal defect is usually performed following strict indications on patients with significant left-to-right shunt. Infective endocarditis after transcatheter implantation of atrial septal defect occluder is an extremely rare complication. We report a case of infective endocarditis of the mitral valve (with severe mitral valve insufficiency in a 39-year-old female patient 13 years after transcatheter closure of an atrial septal defect. Complex prophylactic antibiotic coverage was performed prior to surgical intervention. Surgical removal of atrial septal defect occluder, mitral valve replacement, atrial septal defect closure and left atrial appendage resection were performed. Postoperative course was uneventful.

Regularities of radiation defects build up on oxide materials surface

International Nuclear Information System (INIS)

Bitenbaev, M.I.; Polyakov, A.I.; Tuseev, T.

2005-01-01

Analysis of experimental data by radiation defects study on different oxide elements (silicon, beryllium, aluminium, rare earth elements) irradiated by the photo-, gamma-, neutron-, alpha- radiation, protons and helium ions show, that gas adsorption process on the surface centers and radiation defects build up in metal oxide correlated between themselves. These processes were described by the equivalent kinetic equations for analysis of radiation defects build up in the different metal oxides. It was revealed in the result of the analysis: number of radiation defects are droningly increasing up to limit value with the treatment temperature growth. Constant of radicals death at ionizing radiation increases as well. Amount of surface defects in different oxides defining absorbing activity of these materials looks as: silicon oxide→beryllium oxide→aluminium oxide. So it was found, that most optimal material for absorbing system preparation is silicon oxide by it power intensity and berylium oxide by it adsorption efficiency

Annealing study on radiation-induced defects in 6H-SiC

International Nuclear Information System (INIS)

Pinheiro, M.V.B.; Lingner, T.; Caudepon, F.; Greulich-Weber, S.; Spaeth, J.M.

2004-01-01

We present the results of a systematic isochronal annealing investigation of vacancy-related defects in electron-irradiated n-type 6H-SiC:N. A series of 10 samples cut from a commercial wafer and annealed up to 1200 C after electron-irradiation (1.5 x 10 18 cm -3 ) was characterized with photoluminescence (PL), Magnetic circular dichroism of the absorption (MCDA) and conventional electron paramagnetic resonance (EPR). Apart from less stable triplet-related defects which vanished between 150 C and 300 C, the thermal behavior of three radiation-induced defects was studied: the silicon vacancy (V Si ), the carbon-antisite-carbon-vacancy pair (C Si -V C ) and the D1 center. Their annealing behavior showed that the destruction of the isolated V Si between 750 C and 900 C is followed by the formation of thermally more stable C Si -V C pairs, a result that has been theoretically predicted recently. By further heating the samples the C Si -V C pairs are annealed out between 900 C and 1050 C and were followed by an increase in the D1 center concentration. (orig.)

Analyzing the defect structure of CuO-doped PZT and KNN piezoelectrics from electron paramagnetic resonance.

Science.gov (United States)

Jakes, Peter; Kungl, Hans; Schierholz, Roland; Eichel, Rüdiger-A

2014-09-01

The defect structure for copper-doped sodium potassium niobate (KNN) ferroelectrics has been analyzed with respect to its defect structure. In particular, the interplay between the mutually compensating dimeric (Cu(Nb)'''-V(O)··) and trimeric (V(O)··-Cu(Nb)'''-V(O)··)· defect complexes with 180° and non-180° domain walls has been analyzed and compared to the effects from (Cu'' - V(O)··)(x)× dipoles in CuO-doped lead zirconate titanate (PZT). Attempts are made to relate the rearrangement of defect complexes to macroscopic electromechanical properties.

Atomic structure of defects in GaN:Mg grown with Ga polarity

International Nuclear Information System (INIS)

Liliental-Weber, Z.; Tomaszewicz, T.; Zakharov, D.; Jasinski, J.; O'Keefe, M.A.; Hautakangas, S.; Laakso, A.; Saarinen, K.

2003-01-01

Electron microscope phase images, produced by direct reconstruction of the scattered electron wave from a focal series of high-resolution images, were used to determine the nature of defects formed in GaN:Mg crystals. We studied bulk crystals grown from dilute solutions of atomic nitrogen in liquid gallium at high pressure and thin films grown by the MOCVD method. All the crystals were grown with Ga-polarity. In both types of samples the majority of defects were three dimensional Mg-rich hexagonal pyramids with bases on the (0001) plane and six walls on {11(und 2)3} planes seen in cross-section as triangulars. Some other defects appear in cross-section as trapezoidal (rectangular) defects as a result of presence of truncated pyramids. Both type of defects have hollow centers. They are decorated by Mg on all six side walls and a base. The GaN which grows inside on the defect walls shows polarity inversion. It is shown that change of polarity starts from the defect tip and propagates to the base, and that the stacking sequence changes from ab in the matrix to bc inside the defect. Exchange of the Ga sublattice with the N sublattice within the defect leads to 0.6 ± 0.2(angstrom) displacement between Ga sublattices outside and inside the defects. It is proposed that lateral overgrowth of the cavities formed within the defect takes place to restore matrix polarity on the defect base

Stress intensity factors for underclad and through clad defects in a reactor pressure vessel submitted to a pressurised thermal shock

International Nuclear Information System (INIS)

Marie, S.; Menager, Y.; Chapuliot, S.

2005-01-01

CEA has launched important work on the development of a Stress Intensity Factors compendium for cracks in a Reactor Pressure Vessel (RPV) taking into account the cladding. The work is performed by Finite Element analysis with a parametric mesh for two types of defects (under clad defect and through clad defect) and a wide range of geometrical and material parameters. In addition, an analytical stress solution for Pressurised Thermal Shock (PTS) on the RPV is proposed to allow a complete analytical estimation of the stress intensity factor K I for the PTS problem. The results are validated by comparison with a complete 3D finite element calculation performed on a complex and realistic case study

Defects in oxide surfaces studied by atomic force and scanning tunneling microscopy

Directory of Open Access Journals (Sweden)

Thomas König

2011-01-01

Full Text Available Surfaces of thin oxide films were investigated by means of a dual mode NC-AFM/STM. Apart from imaging the surface termination by NC-AFM with atomic resolution, point defects in magnesium oxide on Ag(001 and line defects in aluminum oxide on NiAl(110, respectively, were thoroughly studied. The contact potential was determined by Kelvin probe force microscopy (KPFM and the electronic structure by scanning tunneling spectroscopy (STS. On magnesium oxide, different color centers, i.e., F0, F+, F2+ and divacancies, have different effects on the contact potential. These differences enabled classification and unambiguous differentiation by KPFM. True atomic resolution shows the topography at line defects in aluminum oxide. At these domain boundaries, STS and KPFM verify F2+-like centers, which have been predicted by density functional theory calculations. Thus, by determining the contact potential and the electronic structure with a spatial resolution in the nanometer range, NC-AFM and STM can be successfully applied on thin oxide films beyond imaging the topography of the surface atoms.

A proposed defect tracking model for classifying the inserted defect reports to enhance software quality control.

Science.gov (United States)

Sultan, Torky; Khedr, Ayman E; Sayed, Mostafa

2013-01-01

NONE DECLARED Defect tracking systems play an important role in the software development organizations as they can store historical information about defects. There are many research in defect tracking models and systems to enhance their capabilities to be more specifically tracking, and were adopted with new technology. Furthermore, there are different studies in classifying bugs in a step by step method to have clear perception and applicable method in detecting such bugs. This paper shows a new proposed defect tracking model for the purpose of classifying the inserted defects reports in a step by step method for more enhancement of the software quality.

Positron annihilation study of vacancy-type defects in fast-neutron-irradiated MgO·nAl2O3

Science.gov (United States)

Rahman, Abu Zayed Mohammad Saliqur; Li, Zhuoxin; Cao, Xingzhong; Wang, Baoyi; Wei, Long; Xu, Qiu; Atobe, Kozo

2014-09-01

The positron lifetimes of fast-neutron-irradiated MgO·nAl2O3 single crystals were measured to investigate the formation of cation vacancies. Al monovacancy was possibly observed in samples irradiated by fast neutrons at ultra-low temperatures. Additionally, vacancy-oxygen complex centers were possibly observed in samples irradiated at higher temperatures and fast neutron fluences. Coincidence Doppler broadening (CDB) spectra were measured to obtain information regarding the vicinity of vacancy-type defects. A peak at approximately 11 × 10-3 m0c was observed, which may be due to the presence of oxygen atoms in the neighborhood of the vacancies.

Influence of chemical disorder on energy dissipation and defect evolution in concentrated solid solution alloys

International Nuclear Information System (INIS)

Zhang, Yanwen; Wang, Lumin; Caro, Alfredo; Weber, William J.; Univ. of Tennessee, Knoxville, TN

2015-01-01

A long-standing objective in materials research is to understand how energy is dissipated in both the electronic and atomic subsystems in irradiated materials, and how related non-equilibrium processes may affect defect dynamics and microstructure evolution. Here we show that alloy complexity in concentrated solid solution alloys having both an increasing number of principal elements and altered concentrations of specific elements can lead to substantial reduction in the electron mean free path and thermal conductivity, which has a significant impact on energy dissipation and consequentially on defect evolution during ion irradiation. Enhanced radiation resistance with increasing complexity from pure nickel to binary and to more complex quaternary solid solutions is observed under ion irradiation up to an average damage level of 1 displacement per atom. Understanding how materials properties can be tailored by alloy complexity and their influence on defect dynamics may pave the way for new principles for the design of radiation tolerant structural alloys

Optical properties of implanted Xe color centers in diamond

Science.gov (United States)

Sandstrom, Russell; Ke, Li; Martin, Aiden; Wang, Ziyu; Kianinia, Mehran; Green, Ben; Gao, Wei-bo; Aharonovich, Igor

2018-03-01

Optical properties of color centers in diamond have been the subject of intense research due to their promising applications in quantum photonics. In this work we study the optical properties of Xe related color centers implanted into nitrogen rich (type IIA) and an ultrapure, electronic grade diamond. The Xe defect has two zero phonon lines at ∼794 nm and 811 nm, which can be effectively excited using both green and red excitation, however, its emission in the nitrogen rich diamond is brighter. Near resonant excitation is performed at cryogenic temperatures and luminescence is probed under strong magnetic field. Our results are important towards the understanding of the Xe related defect and other near infrared color centers in diamond.

Reconstruction of Nasal Skin Cancer Defects with Local Flaps

Directory of Open Access Journals (Sweden)

A. C. Salgarelli

2011-01-01

Full Text Available Reconstruction of nasal defects must preserve the integrity of complex facial functions and expressions, as well as facial symmetry and a pleasing aesthetic outcome. The reconstructive modality of choice will depend largely on the location, size, and depth of the surgical defect. Individualized therapy is the best course, and numerous flaps have been designed to provide coverage of a variety of nasal-specific defects. We describe our experience in the aesthetic reconstruction of nasal skin defects following oncological surgery. The use of different local flaps for nasal skin cancer defects is reported in 286 patients. Complications in this series were one partial flap dehiscence that healed by secondary intention, two forehead flaps, and one bilobed flap with minimal rim necrosis that resulted in an irregular scar requiring revision. Aesthetic results were deemed satisfactory by all patients and the operating surgeons. The color and texture matches were aesthetically good, and the nasal contour was distinct in all patients. All scars were inconspicuous and symmetrical. No patient had tenting or a flat nose.

Reconstruction of Nasal Skin Cancer Defects with Local Flaps

International Nuclear Information System (INIS)

Salgarelli, A. C.; Bellini, P.; Multinu, A.; Consolo, U.; Magnoni, C.; Francomano, M.; Fantini, F.; Seidenari, S.

2011-01-01

Reconstruction of nasal defects must preserve the integrity of complex facial functions and expressions, as well as facial symmetry and a pleasing aesthetic outcome. The reconstructive modality of choice will depend largely on the location, size, and depth of the surgical defect. Individualized therapy is the best course, and numerous flaps have been designed to provide coverage of a variety of nasal-specific defects. We describe our experience in the aesthetic reconstruction of nasal skin defects following oncological surgery. The use of different local flaps for nasal skin cancer defects is reported in 286 patients. Complications in this series were one partial flap dehiscence that healed by secondary intention, two forehead flaps, and one bilobed flap with minimal rim necrosis that resulted in an irregular scar requiring revision. Aesthetic results were deemed satisfactory by all patients and the operating surgeons. The color and texture matches were aesthetically good, and the nasal contour was distinct in all patients. All scars were inconspicuous and symmetrical. No patient had tenting or a flat nose.

Spectroscopic properties of reaction center pigments in photosystem II core complexes: revision of the multimer model.

Science.gov (United States)

Raszewski, Grzegorz; Diner, Bruce A; Schlodder, Eberhard; Renger, Thomas

2008-07-01

Absorbance difference spectra associated with the light-induced formation of functional states in photosystem II core complexes from Thermosynechococcus elongatus and Synechocystis sp. PCC 6803 (e.g., P(+)Pheo(-),P(+)Q(A)(-),(3)P) are described quantitatively in the framework of exciton theory. In addition, effects are analyzed of site-directed mutations of D1-His(198), the axial ligand of the special-pair chlorophyll P(D1), and D1-Thr(179), an amino-acid residue nearest to the accessory chlorophyll Chl(D1), on the spectral properties of the reaction center pigments. Using pigment transition energies (site energies) determined previously from independent experiments on D1-D2-cytb559 complexes, good agreement between calculated and experimental spectra is obtained. The only difference in site energies of the reaction center pigments in D1-D2-cytb559 and photosystem II core complexes concerns Chl(D1). Compared to isolated reaction centers, the site energy of Chl(D1) is red-shifted by 4 nm and less inhomogeneously distributed in core complexes. The site energies cause primary electron transfer at cryogenic temperatures to be initiated by an excited state that is strongly localized on Chl(D1) rather than from a delocalized state as assumed in the previously described multimer model. This result is consistent with earlier experimental data on special-pair mutants and with our previous calculations on D1-D2-cytb559 complexes. The calculations show that at 5 K the lowest excited state of the reaction center is lower by approximately 10 nm than the low-energy exciton state of the two special-pair chlorophylls P(D1) and P(D2) which form an excitonic dimer. The experimental temperature dependence of the wild-type difference spectra can only be understood in this model if temperature-dependent site energies are assumed for Chl(D1) and P(D1), reducing the above energy gap from 10 to 6 nm upon increasing the temperature from 5 to 300 K. At physiological temperature, there are

Influence of stacking fault energies on the size distribution and character of defect clusters formed by collision cascades in face-centered cubic metals

Directory of Open Access Journals (Sweden)

Y. Yang

2016-12-01

Full Text Available Molecular dynamics simulations are performed to evaluate the influence of the stacking fault energy (SFE as a single variable parameter on defect formation by collision cascades in face-centered cubic metals. The simulations are performed for energies of a primary knock-on atom (EPKA up to 50keV at 100K by using six sets of the recently developed embedded atom method–type potentials. Neither the number of residual defects nor their clustering behavior is found to be affected by the SFE, except for the mean size of the vacancy clusters at EPKA=50keV. The mean size increases as the SFE decreases because of the enhanced formation of large vacancy clusters, which prefer to have stacking faults inside them. On the other hand, the ratio of glissile self-interstitial atom (SIA clusters decreases as the SFE increases. At higher SFEs, both the number of Frank loops and number of perfect loops tend to decrease; instead, three-dimensional irregular clusters with higher densities appear, most of which are sessile. The effect of SFE on the number of Frank loops becomes apparent only at a high EPKA of 50keV, where comparably large SIA clusters can be formed with a higher density.

Lattice defects in rutile, TiO2

International Nuclear Information System (INIS)

Nakagawa, M.; Itoh, H.; Nakanishi, S.; Kondo, K.; Okada, M.; Atobe, K.

1991-01-01

Rutile, TiO 2 , having a relatively high melting point exhibits strong optical absorption after neutron irradiation (8 x 10 16 n f /cm 2 ) at 15K. The band peak is located near 0.96 μ, having a FWHM of 0.87 eV (at liquid nitrogen temperature). After inverse recovery at 120K, lattice defects due probably to F centers are annealed out at about 220K. (author)

A Comparative Experimental Study on Identification of Defect Severity in Rolling Element Bearings using Acoustic Emission and Vibration Analysis

Directory of Open Access Journals (Sweden)

V.V. Rao

2015-06-01

Full Text Available This paper describes the comparison between Vibration Analysis (VA and Acoustic Emission (AE method to predict the defect severity in rolling element bearings with respect to the gradual increase of defect size. In bearing fault diagnosis vibration based methods are very popular, but the signals acquired by its transducers from the bearings are distorted by other faults and mechanical noise from the equipment. Vibration based methods are effective when the defect in the bearings has already become severe. AE is a non destructive testing (NDT technique used in structural health monitoring and its application for bearing defect diagnosis is gaining momentum as an alternate diagnostic tool because of its inherent high signal-to-noise-ratio (SNR. A bearing test rig was designed and set up to study the various defects in rolling element bearings in real environment. In earlier cases, though the researchers studied on different types of seeded defects with random sizes, they could not ascertain the correlation between their defect sizes and the vibration amplitude. The experimental investigation reported in this paper is centered on seeded defect of same type with gradual increase of its size on outer race of radially loaded cylindrical roller bearings and running the defective bearing at different speeds and loads. Data acquired through AE & vibration probes simultaneously for better diagnosis. Comparisons between AE and VA over a range of speed and load conditions at gradual increase of defect size are presented and from them it is concluded that AE method is superior to identify the severity of defect.

Optical spectroscopy and microscopy of radiation-induced light-emitting point defects in lithium fluoride crystals and films

Science.gov (United States)

Montereali, R. M.; Bonfigli, F.; Menchini, F.; Vincenti, M. A.

2012-08-01

Broad-band light-emitting radiation-induced F2 and F3+ electronic point defects, which are stable and laser-active at room temperature in lithium fluoride crystals and films, are used in dosimeters, tuneable color-center lasers, broad-band miniaturized light sources and novel radiation imaging detectors. A brief review of their photoemission properties is presented, and their behavior at liquid nitrogen temperatures is discussed. Some experimental data from optical spectroscopy and fluorescence microscopy of these radiation-induced point defects in LiF crystals and thin films are used to obtain information about the coloration curves, the efficiency of point defect formation, the effects of photo-bleaching processes, etc. Control of the local formation, stabilization, and transformation of radiation-induced light-emitting defect centers is crucial for the development of optically active micro-components and nanostructures. Some of the advantages of low temperature measurements for novel confocal laser scanning fluorescence microscopy techniques, widely used for spatial mapping of these point defects through the optical reading of their visible photoluminescence, are highlighted.

Electron paramagnetic resonance of isolated Assub(Ga)+ antisite defect in neutron-transmutation doped semi-insulating GaAs

International Nuclear Information System (INIS)

Manasreh, M.O.; McDonald, P.F.; Kivlighn, S.A.; Minton, J.T.; Covington, B.C.

1988-01-01

The isolated Assub(Ga) antisite defect produced by the neutron-transmutation doping in semi-insulating GaAs was studied using the electron paramagnetic resonance technique. The results show that the optically induced quenching of the isolated Assub(Ga) + antisite defect is quite different from that of the EL2 center. Illumination with white light seems to always reduce the electron paramagnetic resonance spectrum suggesting that depopulation of the EL2 center does not introduce a noticeable change in the Assub(Ga) + antisite concentration. (author)