The multiple roles of small-angle tilt grain boundaries in annihilating radiation damage in SiC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang, Hao; Wang, Xing; Szlufarska, Izabela

Lattice defects generated by radiation damage can diffuse to grain boundaries (GBs) and be annihilated at GBs. However, the precise role of GBs in annihilating the segregated defects remains unclear. Here, we employed multi-scale models to determine how interstitials are annihilated at small-angle tilt GBs (STGBs) in SiC. First of all, we found the pipe diffusion of interstitials in STGBs is slower than bulk diffusion. This is because the increased interatomic distance at dislocation cores raises the migration barrier of interstitial dumbbells. Furthermore, we found both the annihilation of interstitials at jogs and jog nucleation from clusters are diffusion-controlled andmore » can occur under off-stoichiometric interstitial fluxes. Finally, a dislocation line model is developed to predict the role of STGBs in annihilating radiation damage. This model includes defect flux to GBs, pipe diffusion in STGBs, and the interaction of defects with jogs. The model predicts the role of STGBs in annihilating defects depends on the rate of defects segregation to and diffusion along STGBs. STGBs mainly serve as diffusion channel for defects to reach other sinks when defect diffusivity is high at boundaries. As a result, when defect diffusivity is low, most of the defects segregated to STGBs are annihilated by dislocation climb.« less

The effects of self-interstitial clusters on cascade defect evolution beyond the primary damage state

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heinisch, H.L.

1997-04-01

The intracascade evolution of the defect distributions of cascades in copper is investigated using stochastic annealing simulations applied to cascades generated with molecular dynamics (MD). The temperature and energy dependencies of annihilation, clustering and free defect production are determined for individual cascades. The annealing simulation results illustrate the strong influence on intracascade evolution of the defect configuration existing in the primary damage state. Another factor significantly affecting the evolution of the defect distribution is the rapid one-dimensional diffusion of small, glissile interstitial loops produced directly in cascades. This phenomenon introduces a cascade energy dependence of defect evolution that is apparentmore » only beyond the primary damage state, amplifying the need for further study of the annealing phase of cascade evolution and for performing many more MD cascade simulations at higher energies.« less

Oxygen transport in off-stoichiometric uranium dioxide mediated by defect clustering dynamics

DOE PAGES

Yu, Jianguo; Bai, Xian -Ming; El-Azab, Anter; ...

2015-03-05

In this study, oxygen transport is central to many properties of oxides such as stoichiometric changes, phase transformation and ionic conductivity. In this paper, we report a mechanism for oxygen transport in uranium dioxide (UO 2) in which the kinetics is mediated by defect clustering dynamics. In particular, the kinetic Monte Carlo (KMC) method has been used to investigate the kinetics of oxygen transport in UO 2 under the condition of creation and annihilation of oxygen vacancies and interstitials as well as oxygen interstitial clustering, with variable offstoichiometry and temperature conditions. It is found that in hypo-stoichiometric UO 2-x, oxygenmore » transport is well described by the vacancy diffusion mechanism while in hyper-stoichiometric UO 2+x, oxygen interstitial cluster diffusion contributes significantly to oxygen transport kinetics, particularly at high temperatures and high off-stoichiometry levels. It is also found that diinterstitial clusters and single interstitials play dominant roles in oxygen diffusion while other larger clusters have negligible contributions. However, the formation, coalescence and dissociation of these larger clusters indirectly affects the overall oxygen diffusion due to their interactions with mono and di-interstitials, thus providing a explanation of the experimental observation of saturation or even drop of oxygen diffusivity at high off-stoichiometry.« less

Effects of applied strain on nanoscale self-interstitial cluster formation in BCC iron

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Ning; Setyawan, Wahyu; Kurtz, Richard J.

2017-09-01

The effect of applied strains on the configurational evolution of self-interstitial clusters in BCC iron (Fe) is explored with atomistic simulations. A novel cluster configuration is discovered at low temperatures (<600 K), which consists of <110> dumbbells and <111> crowdions in a specific configuration, resulting in an immobile defect. The stability and diffusion of this cluster at higher temperatures is explored. In addition, an anisotropy distribution factor of a particular [hkl] interstitial loop within the family of loops is calculated as a function of strain. The results show that loop anisotropy is governed by the angle between the stress directionmore » and the orientation of the <111> crowdions in the loop, and directly linked to the stress induced preferred nucleation of self-interstitial atoms.« less

First-Principles Study of Carbon and Vacancy Structures in Niobium

DOE PAGES

Ford, Denise C.; Zapol, Peter; Cooley, Lance D.

2015-04-03

The interstitial chemical impurities hydrogen, oxygen, nitrogen, and carbon are important for niobium metal production, and particularly for the optimization of niobium SRF technology. These atoms are present in refined sheets and can be absorbed into niobium during processing treatments, resulting in changes to the residual resistance and the performance of SRF cavities. A first-principles approach is taken to study the properties of carbon in niobium, and the results are compared and contrasted with the properties of the other interstitial impurities. The results indicate that C will likely form precipitates or atmospheres around defects rather than strongly bound complexes withmore » other impurities. Based on the analysis of carbon and hydrogen near niobium lattice vacancies and small vacancy chains and clusters, the formation of extended carbon chains and hydrocarbons is not likely to occur. Association of carbon with hydrogen atoms can, however, occur through the strain fields created by interstitial binding of the impurity atoms. In conclusion, calculated electronic densities of states indicate that interstitial C may have a similar effect as interstitial O on the superconducting transition temperature of Nb.« less

Effects of applied strain on nanoscale self-interstitial cluster formation in BCC iron

NASA Astrophysics Data System (ADS)

Gao, Ning; Setyawan, Wahyu; Kurtz, Richard J.; Wang, Zhiguang

2017-09-01

The effect of applied strains on the configurational evolution of self-interstitial clusters in BCC iron (Fe) is explored with atomistic simulations. A novel cluster configuration is discovered at low temperatures (<600 K), which consists of 〈 110 〉 dumbbells and 〈 111 〉 crowdions in a specific configuration, resulting in an immobile defect. The stability and diffusion of this cluster at higher temperatures is explored. In addition, an anisotropy distribution factor of a particular [ hkl ] interstitial loop within the family of 〈 hkl 〉 loops is calculated as a function of strain. The results show that loop anisotropy is governed by the angle between the stress direction and the orientation of the 〈 111 〉 crowdions in the loop, and directly linked to the stress induced preferred nucleation of self-interstitial atoms.

Defect processes in Be12X (X = Ti, Mo, V, W)

NASA Astrophysics Data System (ADS)

Jackson, M. L.; Burr, P. A.; Grimes, R. W.

2017-08-01

The stability of intrinsic point defects in Be12X intermetallics (where X  =  Ti, V, Mo or W) are predicted using density functional theory simulations and discussed with respect to fusion energy applications. Schottky disorder is found to be the lowest energy complete disorder process, closely matched by Be Frenkel disorder in the cases of Be12V and Be12Ti. Antitisite and X Frenkel disorder are of significantly higher energy. Small clusters of point defects including Be divacancies, Be di-interstitials and accommodation of the X species on two Be sites were considered. Some di-interstitial, divacancy and X2Be combinations exhibit negative binding enthalpy (i.e. clustering is favourable), although this is orientationally dependent. None of the Be12X intermetallics are predicted to exhibit significant non-stoichiometry, ruling out non-stoichiometry as a mechanism for accommodating Be depletion due to neutron transmutation.

Average structure and local configuration of excess oxygen in UO(2+x).

PubMed

Wang, Jianwei; Ewing, Rodney C; Becker, Udo

2014-03-19

Determination of the local configuration of interacting defects in a crystalline, periodic solid is problematic because defects typically do not have a long-range periodicity. Uranium dioxide, the primary fuel for fission reactors, exists in hyperstoichiometric form, UO(2+x). Those excess oxygen atoms occur as interstitial defects, and these defects are not random but rather partially ordered. The widely-accepted model to date, the Willis cluster based on neutron diffraction, cannot be reconciled with the first-principles molecular dynamics simulations present here. We demonstrate that the Willis cluster is a fair representation of the numerical ratio of different interstitial O atoms; however, the model does not represent the actual local configuration. The simulations show that the average structure of UO(2+x) involves a combination of defect structures including split di-interstitial, di-interstitial, mono-interstitial, and the Willis cluster, and the latter is a transition state that provides for the fast diffusion of the defect cluster. The results provide new insights in differentiating the average structure from the local configuration of defects in a solid and the transport properties of UO(2+x).

The thermodynamic and kinetic interactions of He interstitial clusters with bubbles in W

DOE PAGES

Perez, Danny; Sandoval, Luis; Uberuaga, Blas P.; ...

2016-05-26

Due to its enviable properties, tungsten is a leading candidate plasma facing material in nuclear fusion reactors. But, like many other metals, tungsten is known to be affected by the high doses of helium atoms incoming from the plasma. Indeed, the implanted interstitial helium atoms cluster together and, upon reaching a critical cluster size, convert into substitutional nanoscale He bubbles. These bubbles then grow by absorbing further interstitial clusters from the matrix. This process can lead to deleterious changes in microstructure, degradation of mechanical properties, and contamination of the plasma. In order to better understand the growth process, we usemore » traditional and accelerated molecular dynamics simulations to investigate the interactions between interstitial He clusters and pre-existing bubbles. These interactions are characterized in terms of thermodynamics and kinetics. We also show that the proximity of the bubble leads to an enhancement of the trap mutation rate and, consequently, to the nucleation of satellite bubbles in the neighborhood of existing ones. Finally, we uncover a number of mechanisms that can lead to the subsequent annihilation of such satellite nanobubbles.« less

The thermodynamic and kinetic interactions of He interstitial clusters with bubbles in W

NASA Astrophysics Data System (ADS)

Perez, Danny; Sandoval, Luis; Uberuaga, Blas P.; Voter, Arthur F.

2016-05-01

Due to its enviable properties, tungsten is a leading candidate plasma facing material in nuclear fusion reactors. However, like many other metals, tungsten is known to be affected by the high doses of helium atoms incoming from the plasma. Indeed, the implanted interstitial helium atoms cluster together and, upon reaching a critical cluster size, convert into substitutional nanoscale He bubbles. These bubbles then grow by absorbing further interstitial clusters from the matrix. This process can lead to deleterious changes in microstructure, degradation of mechanical properties, and contamination of the plasma. In order to better understand the growth process, we use traditional and accelerated molecular dynamics simulations to investigate the interactions between interstitial He clusters and pre-existing bubbles. These interactions are characterized in terms of thermodynamics and kinetics. We show that the proximity of the bubble leads to an enhancement of the trap mutation rate and, consequently, to the nucleation of satellite bubbles in the neighborhood of existing ones. We also uncover a number of mechanisms that can lead to the subsequent annihilation of such satellite nanobubbles.

Transport properties of dilute α -Fe (X ) solid solutions (X = C, N, O)

NASA Astrophysics Data System (ADS)

Schuler, Thomas; Nastar, Maylise

2016-06-01

We extend the self-consistent mean field (SCMF) method to the calculation of the Onsager matrix of Fe-based interstitial solid solutions. Both interstitial jumps and substitutional atom-vacancy exchanges are accounted for. A general procedure is introduced to split the Onsager matrix of a dilute solid solution into intrinsic cluster Onsager matrices, and extract from them flux-coupling ratios, mobilities, and association-dissociation rates for each cluster. The formalism is applied to vacancy-interstitial solute pairs in α -Fe (V X pairs, X = C, N, O), with ab initio based thermodynamic and kinetic parameters. Convergence of the cluster mobility contribution gives a controlled estimation of the cluster definition distance, taking into account both its thermodynamic and kinetic properties. Then, the flux-coupling behavior of each V X pair is discussed, and qualitative understanding is achieved from the comparison between various contributions to the Onsager matrix. Also, the effect of low-activation energy second-nearest-neighbor interstitial solute jumps around a vacancy on these results is addressed.

Grain boundary resistance to amorphization of nanocrystalline silicon carbide

PubMed Central

Chen, Dong; Gao, Fei; Liu, Bo

2015-01-01

Under the C displacement condition, we have used molecular dynamics simulation to examine the effects of grain boundaries (GBs) on the amorphization of nanocrystalline silicon carbide (nc-SiC) by point defect accumulation. The results show that the interstitials are preferentially absorbed and accumulated at GBs that provide the sinks for defect annihilation at low doses, but also driving force to initiate amorphization in the nc-SiC at higher doses. The majority of surviving defects are C interstitials, as either C-Si or C-C dumbbells. The concentration of defect clusters increases with increasing dose, and their distributions are mainly observed along the GBs. Especially these small clusters can subsequently coalesce and form amorphous domains at the GBs during the accumulation of carbon defects. A comparison between displacement amorphized nc-SiC and melt-quenched single crystal SiC shows the similar topological features. At a dose of 0.55 displacements per atom (dpa), the pair correlation function lacks long range order, demonstrating that the nc-SiC is fully amorphilized. PMID:26558694

Grain boundary resistance to amorphization of nanocrystalline silicon carbide.

PubMed

Chen, Dong; Gao, Fei; Liu, Bo

2015-11-12

Under the C displacement condition, we have used molecular dynamics simulation to examine the effects of grain boundaries (GBs) on the amorphization of nanocrystalline silicon carbide (nc-SiC) by point defect accumulation. The results show that the interstitials are preferentially absorbed and accumulated at GBs that provide the sinks for defect annihilation at low doses, but also driving force to initiate amorphization in the nc-SiC at higher doses. The majority of surviving defects are C interstitials, as either C-Si or C-C dumbbells. The concentration of defect clusters increases with increasing dose, and their distributions are mainly observed along the GBs. Especially these small clusters can subsequently coalesce and form amorphous domains at the GBs during the accumulation of carbon defects. A comparison between displacement amorphized nc-SiC and melt-quenched single crystal SiC shows the similar topological features. At a dose of 0.55 displacements per atom (dpa), the pair correlation function lacks long range order, demonstrating that the nc-SiC is fully amorphilized.

Ab initio simulations of the structure, energetics and mobility of radiation-induced point defects in bcc Nb

NASA Astrophysics Data System (ADS)

Cerdeira, M. A.; Palacios, S. L.; González, C.; Fernández-Pello, D.; Iglesias, R.

2016-09-01

The formation, binding and migration energetics of helium clusters inside a niobium crystal have been analysed via ab initio simulations. The effect of placing several He atoms within an n-vacancy previously formed or as interstitials inside the initial perfect bulk matrix has been studied. DFT-based results show that He atoms prefer to aggregate forming small clusters at n-vacancy sites rather than at interstitial positions in the perfect crystal. The minimum formation energy is found when NHe is equal to the number of vacancies, n. It follows that vacancies act as almost perfect traps for He atoms, as is well known for other metals. The migration barriers of He atoms inside vacancies increase considerably when compared to what happens for vacancies alone. A secondary consequence is that the full set of energies obtained will be highly relevant as an input for new approaches to KMC simulations of defects in Nb.

Evolution of Radiation Induced Defects in SiC: A Multiscale Simulation Approach

NASA Astrophysics Data System (ADS)

Jiang, Hao

Because of various excellent properties, SiC has been proposed for many applications in nuclear reactors including cladding layers in fuel rod, fission products container in TRISO fuel, and first wall/blanket in magnetic controlled fusion reactors. Upon exposure to high energy radiation environments, point defects and defect clusters are generated in materials in amounts significantly exceeding their equilibrium concentrations. The accumulation of defects can lead to undesired consequences such as crystalline-to-amorphous transformation1, swelling, and embrittlement, and these phenomena can adversely affect the lifetime of SiC based components in nuclear reactors. It is of great importance to understand the accumulation process of these defects in order to estimate change in properties of this material and to design components with superior ability to withstand radiation damages. Defect clusters are widely in SiC irradiated at the operation temperatures of various reactors. These clusters are believed to cause more than half of the overall swelling of irradiated SiC and can potentially lead to lowered thermal conductivity and mechanical strength. It is critical to understand the formation and growth of these clusters. Diffusion of these clusters is one importance piece to determine the growth rate of clusters; however it is unclear so far due to the challenges in simulating rare events. Using a combination of kinetic Activation Relaxation Technique with empirical potential and ab initio based climbing image nudged elastic band method, I performed an extensive search of the migration paths of the most stable carbon tri-interstitial cluster in SiC. This research reveals paths with the lowest energy barriers to migration, rotation, and dissociation of the most stable cluster. Based on these energy barriers, I concluded defect clusters are thermally immobile at temperatures lower than 1500 K and can dissociate into smaller clusters and single interstitials at temperatures beyond that. Even though clusters cannot diffuse by thermal vibrations, we found they can migrate at room temperature under the influence of electron radiation. This is the first direct observation of radiation-induced diffusion of defect clusters in bulk materials. We show that the underlying mechanism of this athermal diffusion is elastic collision between incoming electrons and cluster atoms. Our findings suggest that defect clusters may be mobile under certain irradiation conditions, changing current understanding of cluster annealing process in irradiated SiC. With the knowledge of cluster diffusion in SiC demonstrated in this thesis, we now become able to predict cluster evolution in SiC with good agreement with experimental measurements. This ability can enable us to estimate changes in many properties of irradiated SiC relevant for its applications in reactors. Internal interfaces such as grain boundaries can behave as sinks to radiation induced defects. The ability of GBs to absorb, transport, and annihilate radiation-induced defects (sink strength) is important to understand radiation response of polycrystalline materials and to better design interfaces for improved resistance to radiation damage. Nowadays, it is established GBs' sink strength is not a static property but rather evolves with many factors, including radiation environments, grain size, and GB microstructure. In this thesis, I investigated the response of small-angle tilt and twist GBs to point defects fluxes in SiC. First of all, I found the pipe diffusion of interstitials in tilt GBs is slower than bulk diffusion. This is because the increased interatomic distance at dislocation cores raises the migration barrier of interstitial dumbbells. Furthermore, I show that both the annihilation of interstitials at jogs and jog nucleation from clusters are diffusion-controlled and can occur under off-stoichiometric interstitial fluxes. Finally, a dislocation line model is developed to predict the role of tilt GBs in annihilating radiation damage. The model predicts the role of tilt GBs in annihilating defects depends on the rate of defects segregation to and diffusion along tilt GBs. Tilt GBs mainly serve as diffusion channel for defects to reach other sinks when defect diffusivity is high at boundaries. When defect diffusivity is low, most of the defects segregated to tilt GBs are annihilated by dislocation climb. Up-to-date, the response of twist GBs under irradiation has been rarely reported in literature and is still unclear. It is important to develop atom scale insight on this question in order to predict twist GBs' sink strength for a better understanding of radiation response of polycrystalline materials. By using a combination of molecular dynamics and grand canonical Monte Carlo, here I demonstrate the defect kinetics in {001} and {111} twist GBs and the microstructural evolution of these GBs under defect fluxes in SiC. I found due to the deep potential well for interstitials at dislocation intersections within the interface, the mobility of defects on dislocation grid is retard and this leads to defect accumulation at GBs for many cases. Furthermore, I conclude both types of twist GBs have to form mixed dislocations with edge component in order to absorb accumulated interstitials at the interface. The formation of mixed dislocation is either by interstitial loop nucleation or by dislocation reactions at the interface. The continuous formation and climb of these mixed dislocations make twist GBs unsaturatable sinks to radiation induced defects.

On Defect Cluster Aggregation and Non-Reducibilty in Tin-Doped Indium Oxide

NASA Astrophysics Data System (ADS)

Warschkow, Oliver; Ellis, Donald E.; Gonzalez, Gabriela; Mason, Thomas O.

2003-03-01

The conductivity of tin-doped indium oxide (ITO), a transparent conductor, is critically dependent on the amount of tin-doping and oxygen partial pressure during preparation and annealing. Frank and Kostlin (Appl. Phys. A 27 (1982) 197-206) rationalized the carrier concentration dependence by postulating the formation of two types of neutral defect clusters at medium tin-doping levels: "Reducible" and "non-reducible" defect clusters; so named to indicate their ability to create carriers under reduction. According to Frank and Kostlin, both are composed of a single oxygen interstitial and two tin atoms substituting for indium, positioned in non-nearest and nearest coordination, respectively. This present work, seeking to distinguish reducible and non-reducible clusters by use of an atomistic model, finds only a weak correlation of oxygen interstitial binding energies with the relative positioning of dopants. Instead, the number of tin-dopants in the vicinity of the interstitial has a much larger effect on how strongly it is bound, a simple consequence of Coulomb interactions. We postulate that oxygen interstitials become non-reducible when clustered with three or more Sn_In. This occurs at higher doping levels as reducible clusters aggregate and share tin atoms. A simple probabilistic model, estimating the average number of clusters so aggregated, provides a qualitatively correct description of the carrier density in reduced ITO as a function of Sn doping level.

Characterization of Oxygen Defect Clusters in UO2+ x Using Neutron Scattering and PDF Analysis.

PubMed

Ma, Yue; Garcia, Philippe; Lechelle, Jacques; Miard, Audrey; Desgranges, Lionel; Baldinozzi, Gianguido; Simeone, David; Fischer, Henry E

2018-06-18

In hyper-stoichiometric uranium oxide, both neutron diffraction work and, more recently, theoretical analyses report the existence of clusters such as the 2:2:2 cluster, comprising two anion vacancies and two types of anion interstitials. However, little is known about whether there exists a region of low deviation-from-stoichiometry in which defects remain isolated, or indeed whether at high deviation-from-stoichiometry defect clusters prevail that contain more excess oxygen atoms than the di-interstitial cluster. In this study, we report pair distribution function (PDF) analyses of UO 2 and UO 2+ x ( x ≈ 0.007 and x ≈ 0.16) samples obtained from high-temperature in situ neutron scattering experiments. PDF refinement for the lower deviation from stoichiometry sample suggests the system is too dilute to differentiate between isolated defects and di-interstitial clusters. For the UO 2.16 sample, several defect structures are tested, and it is found that the data are best represented assuming the presence of center-occupied cuboctahedra.

Clustering of Ca2+ transients in interstitial cells of Cajal defines slow wave duration

PubMed Central

Drumm, Bernard T.; Hennig, Grant W.; Battersby, Matthew J.; Sung, Tae Sik

2017-01-01

Interstitial cells of Cajal (ICC) in the myenteric plexus region (ICC-MY) of the small intestine are pacemakers that generate rhythmic depolarizations known as slow waves. Slow waves depend on activation of Ca2+-activated Cl− channels (ANO1) in ICC, propagate actively within networks of ICC-MY, and conduct to smooth muscle cells where they generate action potentials and phasic contractions. Thus, mechanisms of Ca2+ regulation in ICC are fundamental to the motor patterns of the bowel. Here, we characterize the nature of Ca2+ transients in ICC-MY within intact muscles, using mice expressing a genetically encoded Ca2+ sensor, GCaMP3, in ICC. Ca2+ transients in ICC-MY display a complex firing pattern caused by localized Ca2+ release events arising from multiple sites in cell somata and processes. Ca2+ transients are clustered within the time course of slow waves but fire asynchronously during these clusters. The durations of Ca2+ transient clusters (CTCs) correspond to slow wave durations (plateau phase). Simultaneous imaging and intracellular electrical recordings revealed that the upstroke depolarization of slow waves precedes clusters of Ca2+ transients. Summation of CTCs results in relatively uniform Ca2+ responses from one slow wave to another. These Ca2+ transients are caused by Ca2+ release from intracellular stores and depend on ryanodine receptors as well as amplification from IP3 receptors. Reduced extracellular Ca2+ concentrations and T-type Ca2+ channel blockers decreased the number of firing sites and firing probability of Ca2+ transients. In summary, the fundamental electrical events of small intestinal muscles generated by ICC-MY depend on asynchronous firing of Ca2+ transients from multiple intracellular release sites. These events are organized into clusters by Ca2+ influx through T-type Ca2+ channels to sustain activation of ANO1 channels and generate the plateau phase of slow waves. PMID:28592421

Stochastic annealing simulations of defect interactions among subcascades

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heinisch, H.L.; Singh, B.N.

1997-04-01

The effects of the subcascade structure of high energy cascades on the temperature dependencies of annihilation, clustering and free defect production are investigated. The subcascade structure is simulated by closely spaced groups of lower energy MD cascades. The simulation results illustrate the strong influence of the defect configuration existing in the primary damage state on subsequent intracascade evolution. Other significant factors affecting the evolution of the defect distribution are the large differences in mobility and stability of vacancy and interstitial defects and the rapid one-dimensional diffusion of small, glissile interstitial loops produced directly in cascades. Annealing simulations are also performedmore » on high-energy, subcascade-producing cascades generated with the binary collision approximation and calibrated to MD results.« less

DISPLACEMENT CASCADE SIMULATION IN TUNGSTEN UP TO 200 KEV OF DAMAGE ENERGY AT 300, 1025, AND 2050 K

DOE Office of Scientific and Technical Information (OSTI.GOV)

Setyawan, Wahyu; Nandipati, Giridhar; Roche, Kenneth J.

2015-09-22

We generated molecular dynamics database of primary defects that adequately covers the range of tungsten recoil energy imparted by 14-MeV neutrons. During this semi annual period, cascades at 150 and 200 keV at 300 and 1025 K were simulated. Overall, we included damage energy up to 200 keV at 300 and 1025 K, and up to 100 keV at 2050 K. We report the number of surviving Frenkel pairs (NF) and the size distribution of defect clusters. The slope of the NF curve versus cascade damage energy (EMD), on a log-log scale, changes at a transition energy (μ). For EMDmore » > μ, the cascade forms interconnected damage regions that facilitate the formation of large clusters of defects. At 300 K and EMD = 200 keV, the largest size of interstitial cluster and vacancy cluster is 266 and 335, respectively. Similarly, at 1025 K and EMD = 200 keV, the largest size of interstitial cluster and vacancy cluster is 296 and 338, respectively. At 2050 K, large interstitial clusters also routinely form, but practically no large vacancy clusters do« less

The interaction between atomic displacement cascades and tilt symmetrical grain boundaries in α-zirconium

NASA Astrophysics Data System (ADS)

Kapustin, P.; Svetukhin, V.; Tikhonchev, M.

2017-06-01

The atomic displacement cascade simulations near symmetric tilt grain boundaries (GBs) in hexagonal close packed-Zirconium were considered in this paper. Further defect structure analysis was conducted. Four symmetrical tilt GBs -∑14?, ∑14? with the axis of rotation [0 0 0 1] and ∑32?, ∑32? with the axis of rotation ? - were considered. The molecular dynamics method was used for atomic displacement cascades' simulation. A tendency of the point defects produced in the cascade to accumulate near the GB plane, which was an obstacle to the spread of the cascade, was discovered. The results of the point defects' clustering produced in the cascade were obtained. The clusters of both types were represented mainly by single point defects. At the same time, vacancies formed clusters of a large size (more than 20 vacancies per cluster), while self-interstitial atom clusters were small-sized.

Theoretical investigation of microstructure evolution and deformation of zirconium under neutron irradiation

DOE PAGES

Barashev, A. V.; Golubov, S. I.; Stoller, R. E.

2015-06-01

We studied the radiation growth of zirconium using a reaction–diffusion model which takes into account intra-cascade clustering of self-interstitial atoms and one-dimensional diffusion of interstitial clusters. The observed dose dependence of strain rates is accounted for by accumulation of sessile dislocation loops during irradiation. Moreover, the computational model developed and fitted to available experimental data is applied to study deformation of Zr single crystals under irradiation up to hundred dpa. Finally, the effect of cold work and the reasons for negative prismatic strains and co-existence of vacancy and interstitial loops are elucidated.

INTERACTION OF INTERSTITIAL CLUSTERS WITH RHENIUM, OSMIUM, AND TANTALUM IN TUNGSTEN

DOE Office of Scientific and Technical Information (OSTI.GOV)

Setyawan, Wahyu; Nandipati, Giridhar; Kurtz, Richard J.

2016-09-01

In the previous semi annual report, we explored the stability of interstitial clusters in W up to size seven. In this report, we study the binding of those clusters to Re, Os, and Ta atoms. For each cluster size, the three most stable configurations are considered to average the binding property. The average binding energy to a Re decreases from 0.79 eV for a size-1 cluster (a [111] dumbbell) to 0.65 eV for a size-7 cluster. For Os, the binding decreases from 1.61 eV for a [111] dumbbell to 1.34 eV for a size-7 cluster. Tantalum is repulsive to interstitialmore » clusters with binding energy ranges from -0.61 eV for a [111] dumbbell to -0.5 eV for a size-7 cluster.« less

Phosphorus-defect interactions during thermal annealing of ion implanted silicon

NASA Astrophysics Data System (ADS)

Keys, Patrick Henry

Ion implantation of dopant atoms into silicon generates nonequilibrium levels of crystal defects that can lead to the detrimental effects of transient enhanced diffusion (TED), incomplete dopant activation, and p-n junction leakage. In order to control these effects, it is vital to have a clear understanding of dopant-defect interactions and develop models that account for these interactions. This research focuses on experimentally investigating and modeling the clustering of phosphorus dopant atoms with silicon interstitials. Damage recovery of 40keV Si+ implants in phosphorus doped wells is experimentally analyzed. The effects of background phosphorus concentration, self implant dose, and anneal temperature are investigated. Phosphorus concentrations ranging from 2.0 x 1017 to 4.0 x 1019 cm-3 and Si+ doses ranging from 5.0 x 1013 cm-2 to 2.0 x 1014 cm-2 are studied during 650-800°C anneals. A dramatic reduction in the number of interstitials bound in {311} defects with increasing phosphorus background concentration is observed. It is suggested that the reduction of interstitials in {311} defects at high phosphorus concentrations is due to the formation of phosphorus-interstitial clusters (PICs). The critical concentration for clustering (approximately 1.0 x 1019 cm-3 at 750°C) is strongly temperature dependent and in close agreement with the kink concentration of phosphorus diffusion. Information gained from these "well experiments" is applied to the study of direct phosphorus implantation. An experimental study is conducted on 40keV phosphorus implanted to a dose of 1.0 x 1014 cm-2 during 650-800°C anneals. Electrically inactive PICs are shown to form at concentrations below the solid solubility limit due to high interstitial supersaturations. Data useful for developing a model to accurately predict phosphorus diffusion under nonequilibrium conditions are extracted from the experimental results. A cluster-mediated diffusion model is developed using the Florida Object Oriented Process Simulator (FLOOPS). The nucleation of defects is controlled by the diffusion-limited competition for excess interstitials between PICs and {311} clusters. The release of interstitials is driven by cluster dissolution. Modeling results show a strong correlation to those experimentally observed over a wide temporal and thermal domain using a single set of parameters. Improvements in process simulator accuracy are demonstrated with respect to dopant activation, TED, and dose loss.

Simulation of defects in fusion plasma first wall materials

NASA Astrophysics Data System (ADS)

T, Troev; N, Nankov; T, Yoshiie

2014-06-01

Numerical calculations of radiation damages in beryllium, alpha-iron and tungsten irradiated by fusion neutrons were performed using molecular dynamics (MD) simulations. The displacement cascades efficiency has been calculated using the Norgett-Robinson-Torrens (NRT) formula, the universal pair-potential of Ziegler-Biersack-Littmark (ZBL) and the EAM inter-atomic potential. The pair potential overestimates the defects production by a factor of 2. The ZBL pair potential results and the EAM are comparable at higher primary knock-on atom (PKA) energies (E > 100 keV). We found that the most common types of defects are single vacancies, di-vacancies, interstitials and small number of interstitial clusters. On the bases of calculated results, the behavior of vacancies, empty nano-voids and nano-voids with hydrogen and helium were discussed.

Primary damage formation in bcc iron

NASA Astrophysics Data System (ADS)

Stoller, R. E.; Odette, G. R.; Wirth, B. D.

1997-11-01

Primary defect formation in bee iron has been extensively investigated using the methods of molecular dynamics (MD) and Monte Carlo (MC) simulation. This research has employed a modified version of the Finnis-Sinclair interatomic potential. MD was used in the simulation of displacement cascades with energies up to 40 keV and to examine the migration of the interstitial clusters that were observed to form in the cascade simulations. Interstitial cluster binding energies and the stable cluster configurations were determined by structural relaxation and energy minimization using a MC method with simulated annealing. Clusters containing up to 19 interstitials were examined. Taken together with the previous work, these new simulations provide a reasonably complete description of primary defect formation in iron. The results of the displacement cascade simulations have been used to characterize the energy and temperature dependence of primary defect formation in terms of two parameters: (1) the number of surviving point defects and (2) the fraction of the surviving defects that are contained in clusters. The number of surviving point defects is expressed as a fraction of the atomic displacements calculated using the secondary displacement model of Norgett-Robinson-Torrens (NRT). Although the results of the high energy simulations are generally consistent with those obtained at lower energies, two notable exceptions were observed. The first is that extensive subcascade formation at 40 keV leads to a higher defect survival fraction than would be predicted from extrapolation of the results obtained for energies up to 20 keV. The stable defect fraction obtained from the MD simulations is a smoothly decreasing function up to 20 keV. Subcascade formation leads to a slight increase in this ratio at 40 keV, where the value is about the same as at 10 keV. Secondly, the potential for a significant level of in-cascade vacancy clustering was observed. Previous cascade studies employing this potential have reported extensive interstitial clustering, but little evidence of vacancy clustering. Interstitial clusters were found to be strongly bound, with binding energies in excess of 1 eV. The larger clusters exhibited a complex, 3D structure and were composed of <111> crowdions. These clusters were observed to migrate by collective <111> translations with an activation energy on the order of 0.1 eV.

Endohedral beryllium atoms in germanium clusters with eight and fewer vertices: how small can a cluster be and still encapsulate a central atom?

PubMed

Uţă, M M; King, R B

2012-05-31

Structures of the beryllium-centered germanium clusters Be@Ge(n)(z) (n = 8, 7, 6; z = -4, -2, 0, +2) have been investigated by density functional theory to provide some insight regarding the smallest metal cluster that can encapsulate an interstitial atom. The lowest energy structures of the eight-vertex Be@Ge(8)(z) clusters (z = -4, -2, 0, +2) all have the Be atom at the center of a closed polyhedron, namely, a D(4d) square antiprism for Be@Ge(8)(4-), a D(2d) bisdisphenoid for Be@Ge(8)(2-), an ideal O(h) cube for Be@Ge(8), and a C(2v) distorted cube for Be@Ge(8)(2+). The Be-centered cubic structures predicted for Be@Ge(8) and Be@Ge(8)(2+) differ from the previously predicted lowest energy structures for the isoelectronic Ge(8)(2-) and Ge(8). This appears to be related to the larger internal volume of the cube relative to other closed eight-vertex polyhedra. The lowest energy structures for the smaller seven- and six-vertex clusters Be@Ge(n)(z) (n = 7, 6; z = -4, -2, 0, +2) no longer have the Be atom at the center of a closed Ge(n) polyhedron. Instead, either the Ge(n) polyhedron has opened up to provide a larger volume for the Be atom or the Be atom has migrated to the surface of the polyhedron. However, higher energy structures are found in which the Be atom is located at the center of a Ge(n) (n = 7, 6) polyhedron. Examples of such structures are a centered C(2v) capped trigonal prismatic structure for Be@Ge(7)(2-), a centered D(5h) pentagonal bipyramidal structure for Be@Ge(7), a centered D(3h) trigonal prismatic structure for Be@Ge(6)(4-), and a centered octahedral structure for Be@Ge(6). Cluster buildup reactions of the type Be@Ge(n)(z) + Ge(2) → Be@Ge(n+2)(z) (n = 6, 8; z = -4, -2, 0, +2) are all predicted to be highly exothermic. This suggests that interstitial clusters having an endohedral atom inside a bare post transition element polyhedron with eight or fewer vertices are less than the optimum size. This is consistent with the experimental observation of several types of 10-vertex polyhedral bare post transition element clusters with interstitial atoms but the failure to observe such clusters with external polyhedra having eight or fewer vertices.

An improved interatomic potential for xenon in UO2: a combined density functional theory/genetic algorithm approach.

PubMed

Thompson, Alexander E; Meredig, Bryce; Wolverton, C

2014-03-12

We have created an improved xenon interatomic potential for use with existing UO2 potentials. This potential was fit to density functional theory calculations with the Hubbard U correction (DFT + U) using a genetic algorithm approach called iterative potential refinement (IPR). We examine the defect energetics of the IPR-fitted xenon interatomic potential as well as other, previously published xenon potentials. We compare these potentials to DFT + U derived energetics for a series of xenon defects in a variety of incorporation sites (large, intermediate, and small vacant sites). We find the existing xenon potentials overestimate the energy needed to add a xenon atom to a wide set of defect sites representing a range of incorporation sites, including failing to correctly rank the energetics of the small incorporation site defects (xenon in an interstitial and xenon in a uranium site neighboring uranium in an interstitial). These failures are due to problematic descriptions of Xe-O and/or Xe-U interactions of the previous xenon potentials. These failures are corrected by our newly created xenon potential: our IPR-generated potential gives good agreement with DFT + U calculations to which it was not fitted, such as xenon in an interstitial (small incorporation site) and xenon in a double Schottky defect cluster (large incorporation site). Finally, we note that IPR is very flexible and can be applied to a wide variety of potential forms and materials systems, including metals and EAM potentials.

Off-stoichiometric defect clustering in irradiated oxides

NASA Astrophysics Data System (ADS)

Khalil, Sarah; Allen, Todd; EL-Azab, Anter

2017-04-01

A cluster dynamics model describing the formation of vacancy and interstitial clusters in irradiated oxides has been developed. The model, which tracks the composition of the oxide matrix and the defect clusters, was applied to the early stage formation of voids and dislocation loops in UO2, and the effects of irradiation temperature and dose rate on the evolution of their densities and composition was investigated. The results show that Frenkel defects dominate the nucleation process in irradiated UO2. The results also show that oxygen vacancies drive vacancy clustering while the migration energy of uranium vacancies is a rate-limiting factor for the nucleation and growth of voids. In a stoichiometric UO2 under irradiation, off-stoichiometric vacancy clusters exist with a higher concentration of hyper-stoichiometric clusters. Similarly, off-stoichiometric interstitial clusters form with a higher concentration of hyper-stoichiometric clusters. The UO2 matrix was found to be hyper-stoichiometric due to the accumulation of uranium vacancies.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perez, Danny, E-mail: danny-perez@lanl.gov; Sandoval, Luis; Voter, Arthur F.

Due to its enviable properties, tungsten is a leading candidate plasma facing material in nuclear fusion reactors. However, like many other metals, tungsten is known to be affected by the high doses of helium atoms incoming from the plasma. Indeed, the implanted interstitial helium atoms cluster together and, upon reaching a critical cluster size, convert into substitutional nanoscale He bubbles. These bubbles then grow by absorbing further interstitial clusters from the matrix. This process can lead to deleterious changes in microstructure, degradation of mechanical properties, and contamination of the plasma. In order to better understand the growth process, we usemore » traditional and accelerated molecular dynamics simulations to investigate the interactions between interstitial He clusters and pre-existing bubbles. These interactions are characterized in terms of thermodynamics and kinetics. We show that the proximity of the bubble leads to an enhancement of the trap mutation rate and, consequently, to the nucleation of satellite bubbles in the neighborhood of existing ones. We also uncover a number of mechanisms that can lead to the subsequent annihilation of such satellite nanobubbles.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perez, Danny; Sandoval, Luis; Uberuaga, Blas P.

Due to its enviable properties, tungsten is a leading candidate plasma facing material in nuclear fusion reactors. But, like many other metals, tungsten is known to be affected by the high doses of helium atoms incoming from the plasma. Indeed, the implanted interstitial helium atoms cluster together and, upon reaching a critical cluster size, convert into substitutional nanoscale He bubbles. These bubbles then grow by absorbing further interstitial clusters from the matrix. This process can lead to deleterious changes in microstructure, degradation of mechanical properties, and contamination of the plasma. In order to better understand the growth process, we usemore » traditional and accelerated molecular dynamics simulations to investigate the interactions between interstitial He clusters and pre-existing bubbles. These interactions are characterized in terms of thermodynamics and kinetics. We also show that the proximity of the bubble leads to an enhancement of the trap mutation rate and, consequently, to the nucleation of satellite bubbles in the neighborhood of existing ones. Finally, we uncover a number of mechanisms that can lead to the subsequent annihilation of such satellite nanobubbles.« less

Damage structures in fission-neutron irradiated Ni-based alloys at high temperatures

NASA Astrophysics Data System (ADS)

Yamakawa, K.; Shimomura, Y.

1999-01-01

The defects formed in Ni based (Ni-Si, Ni-Cu and Ni-Fe) alloys which were irradiated with fission-neutrons were examined by electron microscopy. Irradiations were carried out at 473 K and 573 K. In the 473 K irradiated specimens, a high density of large interstitial loops and small vacancy clusters with stacking fault tetrahedra (SFT) were observed. The number densities of these two types of defects did not strongly depend on the amount of solute atoms in each alloy. The density of the loops in Ni-Si alloys was much higher than those in Ni-Cu and Ni-Fe alloys, while the density of SFT only slightly depended on the kind of solute. Also, the size of the loops depended on the kinds and amounts of solute. In 573 K irradiated Ni-Cu specimens, a high density of dislocation lines developed during the growth of interstitial loops. In Ni-Si alloys, the number density and size of the interstitial loops changed as a function of the amount of solute. Voids were formed in Ni-Cu alloys but scarcely formed in Ni-Si alloys. The number density of voids was one hundredth of that of SFT observed in 473 K irradiated Ni-Cu alloys. Possible formation processes of interstitial loops, SFT dislocation lines and voids are discussed.

The effects of cation–anion clustering on defect migration in MgAl 2O 4

DOE PAGES

Zamora, Richard J.; Voter, Arthur F.; Perez, Danny; ...

2016-06-28

Magnesium aluminate spinel (MgAl 2O 4), like many other ceramic materials, offers a range of technological applications, from nuclear reactor materials to military body armor. For many of these applications, it is critical to understand both the formation and evolution of lattice defects throughout the lifetime of the material. We use the Speculatively Parallel Temperature Accelerated Dynamics (SpecTAD) method to investigate the effects of di-vacancy and di-interstitial formation on the mobility of the component defects. From long-time trajectories of the state-to-state dynamics, we characterize the migration pathways of defect clusters, and calculate their self-diffusion constants across a range of temperatures.more » We find that the clustering of Al and O vacancies drastically reduces the mobility of both defects, while the clustering of Mg and O vacancies completely immobilizes them. For interstitials, we find that the clustering of Mg and O defects greatly reduces O interstitial mobility, but has only a weak effect on Mg. Lastly, these findings illuminate important new details regarding defect kinetics relevant to the application of MgAl 2O 4 in extreme environments.« less

Atomic diffusion in strain fields near solutes

NASA Astrophysics Data System (ADS)

Shropshire, Steven L.; Collins, Gary S.

1993-03-01

Annihilation reactions between mobile self-interstitial defects and complexes of vacancies with111In probe solutes in Au were studied. Measurements were made using the technique of perturbed angular correlations of gamma rays (PAC). Au samples were doped with complexes and plastically deformed at a low temperature to generate fluxes of self-interstitials. Changes in the concentrations of monovacancy (1V) to tetravacancy (4V) complexes induced by annihilation reactions were measured. These are now analysed using a system of coupled first-order equations in order to obtain interstitial annihilation cross sections of the complexes and the fractional amounts of different interstitial clusters in the flux. Relative cross sections obtained for Au are 1.0(1), 3.3(3), 1.2(2) and 7.5(2.5), respectively, for 1V to 4V complexes. The large increase in the cross sections with vacancy number is attributed to a progressive relaxation of the dilatational strain surrounding the oversized In solute as more vacancies are trapped. Also obtained from the analysis are values 0.34(5), 0.66(7), 0.0(1) and 0.0(2), respectively, for the fractions of mobile 1I to 4I clusters in deformed Au, indicating that di-interstitials are produced more readily than mono-interstitials during plastic deformation.

Change of Energy of the Cubic Subnanocluster of Iron Under Influence of Interstitial and Substitutional Atoms.

PubMed

Nedolya, Anatoliy V; Bondarenko, Natalya V

2016-12-01

Energy change of an iron face-centred cubic subnanocluster was evaluated using molecular mechanics method depending on the position of a carbon interstitial atom and substitutional atoms of nickel. Calculations of all possible positions of impurity atoms show that the energy change of the system are discrete and at certain positions of the atoms are close to continuous.In terms of energy, when all impurity atoms are on the same edge of an atomic cluster, their positions are more advantageous. The presence of nickel atoms on the edge of a cubic cluster resulted in decrease of potential barrier for a carbon atom and decrease in energy in the whole cluster. A similar drift of a carbon atom from central octahedral interstitial site to the surface in the direction <011> occurred under the influence of surface factors.Such configuration corresponds to decreasing symmetry and increasing the number of possible energy states of a subnanocluster, and it corresponds to the condition of spontaneous crystallization process in an isolated system.Taking into account accidental positions of the nickel atom in the iron cluster, such behaviour of the carbon atom can explain the mechanism of growth of a new phase and formation of new clusters in the presence of other kind of atoms because of surface influence.

Cluster dynamics modeling and experimental investigation of the effect of injected interstitials

NASA Astrophysics Data System (ADS)

Michaut, B.; Jourdan, T.; Malaplate, J.; Renault-Laborne, A.; Sefta, F.; Décamps, B.

2017-12-01

The effect of injected interstitials on loop and cavity microstructures is investigated experimentally and numerically for 304L austenitic stainless steel irradiated at 450 °C with 10 MeV Fe5+ ions up to about 100 dpa. A cluster dynamics model is parametrized on experimental results obtained by transmission electron microscopy (TEM) in a region where injected interstitials can be safely neglected. It is then used to model the damage profile and study the impact of self-ion injection. Results are compared to TEM observations on cross-sections of specimens. It is shown that injected interstitials have a significant effect on cavity density and mean size, even in the sink-dominated regime. To quantitatively match the experimental data in the self-ions injected area, a variation of some parameters is necessary. We propose that the fraction of freely migrating species may vary as a function of depth. Finally, we show that simple rate theory considerations do not seem to be valid for these experimental conditions.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Setyawan, Wahyu; Nandipati, Giridhar; Kurtz, Richard J.

The stability of tungsten self-interstitial atom (SIA) clusters is studied using first-principles methods. Clusters from one to seven SIAs are systematically explored from 1264 unique configurations. Finite-size effect of the simulation cell is corrected based on the scaling of formation energy versus inverse volume cell. Furthermore, the accuracy of the calculations is improved by treating the 5p semicore states as valence states. Configurations of the three most stable clusters in each cluster size n are presented, which consist of parallel [111] dumbbells. The evolution of these clusters leading to small dislocation loops is discussed. The binding energy of size-n clustersmore » is analyzed relative to an n → (n-1) + 1 dissociation and is shown to increase with size. Extrapolation for n > 7 is presented using a dislocation loop model. In addition, the interaction of these clusters with a substitutional Re, Os, or Ta solute is explored by replacing one of the dumbbells with the solute. Re and Os strongly attract these clusters, but Ta strongly repels. The strongest interaction is found when the solute is located on the periphery of the cluster rather than in the middle. The magnitude of this interaction decreases with cluster size. Empirical fits to describe the trend of the solute binding energy are presented.« less

Molecular dynamics study of the role of symmetric tilt grain boundaries on the helium distribution in nickel

NASA Astrophysics Data System (ADS)

Torres, E.; Pencer, J.

2018-04-01

Helium impurities, from either direct implantation or transmutation reactions, have been associated with embrittlement in nickel-based alloys. Helium has very low solubility in nickel, and has been found to aggregate at lattice defects such as vacancies, dislocations, and grain boundaries. The retention and precipitation of helium in nickel-based alloys have deleterious effects on the material mechanical properties. However, the underlying mechanisms that lead to helium effects in the host metal are not fully understood. In the present work, we investigate the role of symmetric tilt grain boundary (STGB) structures on the distribution of helium in nickel using molecular dynamics simulations. We investigate the family of STGBs specific to the 〈 110 〉 tilt axis. The present results indicate that accumulation of helium at the grain boundary may be modulated by details of grain boundary geometry. A plausible correlation between the grain boundary energy and misorientation with the accumulation and mobility of helium is proposed. Small clusters with up to 6 helium atoms show significant interstitial mobility in the nickel bulk, but also become sites for nucleation and grow of more stable helium clusters. High-energy GBs are found mainly populated with small helium clusters. The high mobility of small clusters along the GBs indicates the role of these GBs as fast two-dimensional channels for diffusion. In contrast, the accumulation of helium in large helium clusters at low-energy STGB creates a favorable environment for the formation of large helium bubbles, indicating a potential role for low-energy STGB in promoting helium-induced GB embrittlement.

The safety and efficacy of carboplatin plus nanoparticle albumin-bound paclitaxel in the treatment of non-small cell lung cancer patients with interstitial lung disease.

PubMed

Yasuda, Yuichiro; Hattori, Yoshihiro; Tohnai, Rie; Ito, Shoichi; Kawa, Yoshitaka; Kono, Yuko; Urata, Yoshiko; Nogami, Munenobu; Takenaka, Daisuke; Negoro, Shunichi; Satouchi, Miyako

2018-01-01

The optimal chemotherapy regimen for non-small cell lung cancer patients with interstitial lung disease is unclear. We therefore investigated the safety and efficacy of carboplatin plus nab-paclitaxel as a first-line regimen for non-small cell lung cancer in patients with interstitial lung disease. We retrospectively reviewed advanced non-small cell lung cancer patients with interstitial lung disease who received carboplatin plus nab-paclitaxel as a first-line chemotherapy regimen at Hyogo Cancer Center between February 2013 and August 2016. interstitial lung disease was diagnosed according to the findings of pretreatment chest high-resolution computed tomography. Twelve patients were included (male, n = 11; female, n = 1). The overall response rate was 67% and the disease control rate was 100%. The median progression free survival was 5.1 months (95% CI: 2.9-8.3 months) and the median overall survival was 14.9 months (95% CI: 4.8-not reached). A chemotherapy-related acute exacerbation of interstitial lung disease was observed in one patient; the extent of this event was Grade 2. There were no treatment-related deaths. Carboplatin plus nab-paclitaxel, as a first-line chemotherapy regimen for non-small cell lung cancer, showed favorable efficacy and safety in patients with preexisting interstitial lung disease. © The Author 2017. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com

Investigation of defect clusters in ion-irradiated Ni and NiCo using diffuse X-ray scattering and electron microscopy

DOE PAGES

Olsen, Raina J.; Jin, Ke; Lu, Chenyang; ...

2015-11-23

The nature of defect clusters in Ni and Nimore » $$_{50}$$Co$$_{50}$$ (NiCo) irradiated at room temperature with 2–16 MeV Ni ions is studied using asymptotic diffuse X-ray scattering and transmission electron microscopy (TEM). Analysis of the scattering data provides separate size distributions for vacancy and interstitial type defect clusters, showing that both types of defect clusters have a smaller size and higher density in NiCo than in Ni. Diffuse scattering results show good quantitative agreement with TEM results for cluster sizes greater than 4 nm diameter, but find that the majority of vacancy clusters are under 2 nm in NiCo, which, if not detected, would lead to the conclusion that defect density was actually lower in the alloy. Interstitial dislocation loops and stacking fault tetrahedra are identified by TEM. Lastly comparison of diffuse scattering lineshapes to those calculated for dislocation loops and SFTs indicates that most of the vacancy clusters are SFTs.« less

DISPLACEMENT CASCADE SIMULATION IN TUNGSTEN AT 1025 K

DOE Office of Scientific and Technical Information (OSTI.GOV)

Setyawan, Wahyu; Nandipati, Giridhar; Roche, Kenneth J.

2013-09-30

Molecular dynamics simulation was employed to investigate the irradiation damage properties of bulk tungsten at 1025 K (0.25 melting temperature). A comprehensive data set of primary cascade damage was generated up to primary knock-on atom (PKA) energies 100 keV. The dependence of the number of surviving Frenkel pairs (NFP) on the PKA energy (E) exhibits three different characteristic domains presumably related to the different cascade morphologies that form. The low-energy regime < 0.2 keV is characterized by a hit-or-miss type of Frenkel pair (FP) production near the displacement threshold energy of 128 eV. The middle regime 0.3 – 30 keVmore » exhibits a sublinear dependence of log(NFP) vs log(E) associated with compact cascade morphology with a slope of 0.73. Above 30 keV, the cascade morphology consists of complex branches or interconnected damage regions. In this extended morphology, large interstitial clusters form from superposition of interstitials from nearby damage regions. Strong clustering above 30 keV results in a superlinear dependence of log(NFP) vs log(E) with a slope of 1.365. At 100 keV, an interstitial cluster of size 92 and a vacancy cluster of size 114 were observed.« less

Interstitial telomeric sequences in human chromosomes cluster with common fragile sites, mutagen sensitive sites, viral integration sites, cancer breakpoints, proto-oncogenes and breakpoints involved in primate evolution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adekunle, S.S.A.; Wyandt, H.; Mark, H.F.L.

1994-09-01

Recently we mapped the telomeric repeat sequences to 111 interstitial sites in the human genome and to sites of gaps and breaks induced by aphidicolin and sister chromatid exchange sites detected by BrdU. Many of these sites correspond to conserved fragile sites in man, gorilla and chimpazee, to sites of conserved sister chromatid exchange in the mammalian X chromosome, to mutagenic sensitive sites, mapped locations of proto-oncogenes, breakpoints implicated in primate evolution and to breakpoints indicated as the sole anomaly in neoplasia. This observation prompted us to investigate if the interstitial telomeric sites cluster with these sites. An extensive literaturemore » search was carried out to find all the available published sites mentioned above. For comparison, we also carried out a statistical analysis of the clustering of the sites of the telomeric repeats with the gene locations where only nucleotide mutations have been observed as the only chromosomal abnormality. Our results indicate that the telomeric repeats cluster most with fragile sites, mutagenic sensitive sites and breakpoints implicated in primate evolution and least with cancer breakpoints, mapped locations of proto-oncogenes and other genes with nucleotide mutations.« less

Atomistic Simulation of Displacement Cascades in Zircon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Devanathan, Ram; Weber, William J.; Corrales, Louis R.

2002-05-06

Low energy displacement cascades in zircon (ZrSiO4) initiated by a Zr primary knock-on atom have been investigated by molecular dynamics simulations using a Coulombic model for long-range interactions, Buckingham potential for short-range interactions and Ziegler-Biersack potentials for close pair interactions. Displacements were found to occur mainly in the O sublattice, and O replacements by a ring mechanism were predominant. Clusters containing Si interstitials bridged by O interstitials, vacancy clusters and anti-site defects were found to occur. This Si-O-Si bridging is considerable in quenched liquid ZrSiO4.

Controlled Expansion of a Strong-Field Iron Nitride Cluster: Multi-Site Ligand Substitution as a Strategy for Activating Interstitial Nitride Nucleophilicity.

PubMed

Drance, Myles J; Mokhtarzadeh, Charles C; Melaimi, Mohand; Agnew, Douglas W; Moore, Curtis E; Rheingold, Arnold L; Figueroa, Joshua S

2018-05-02

Multimetallic clusters have long been investigated as molecular surrogates for reactive sites on metal surfaces. In the case of the μ 4 -nitrido cluster [Fe 4 (μ 4 -N)(CO) 12 ] - , this analogy is limited owing to the electron-withdrawing effect of carbonyl ligands on the iron nitride core. Described here is the synthesis and reactivity of [Fe 4 (μ 4 -N)(CO) 8 (CNAr Mes2 ) 4 ] - , an electron-rich analogue of [Fe 4 (μ 4 -N)(CO) 12 ] - , where the interstitial nitride displays significant nucleophilicity. This characteristic enables rational expansion with main-group and transition-metal centers to yield unsaturated sites. The resulting clusters display surface-like reactivity through coordination-sphere-dependent atom rearrangement and metal-metal cooperativity. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Long-time atomistic dynamics through a new self-adaptive accelerated molecular dynamics method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, N.; Yang, L.; Gao, F.

2017-02-27

A self-adaptive accelerated molecular dynamics method is developed to model infrequent atomic- scale events, especially those events that occur on a rugged free-energy surface. Key in the new development is the use of the total displacement of the system at a given temperature to construct a boost-potential, which is slowly increased to accelerate the dynamics. The temperature is slowly increased to accelerate the dynamics. By allowing the system to evolve from one steady-state con guration to another by overcoming the transition state, this self-evolving approach makes it possible to explore the coupled motion of species that migrate on vastly differentmore » time scales. The migrations of single vacancy (V) and small He-V clusters, and the growth of nano-sized He-V clusters in Fe for times in the order of seconds are studied by this new method. An interstitial- assisted mechanism is rst explored for the migration of a helium-rich He-V cluster, while a new two-component Ostwald ripening mechanism is suggested for He-V cluster growth.« less

Deficiency of interstitial cells of Cajal in the small intestine of patients with Crohn's disease.

PubMed

Porcher, Christophe; Baldo, Marjolaine; Henry, Monique; Orsoni, Pierre; Julé, Yvon; Ward, Sean M

2002-01-01

Interstitial cells of Cajal are critical for the generation of electrical slow waves that regulate the phasic contractile activity of the tunica muscularis of the GI tract. Under certain pathophysiological conditions loss of interstitial cells of Cajal may play a role in the generation of certain motility disorders. The aim of the present study was to determine if there is an abnormality in the density or distribution of interstitial cells of Cajal from patients with Crohn's disease. Small intestines from control subjects and patients with Crohn's disease were examined using immunohistochemistry and antibodies against the Kit receptor, which is expressed in interstitial cells of Cajal within the tunica muscularis of the GI tract. The density and distribution of interstitial cells of Cajal were assessed in the longitudinal and circular muscle layers and in the myenteric and deep muscular plexus regions of Crohn's and control tissues. Tissues from Crohn's disease patients showed an almost complete abolition of interstitial cells of Cajal within the longitudinal and circular muscle layers and a significant reduction in numbers at the level of the myenteric and deep muscular plexuses. In tissues from Crohn's disease patients, the density of interstitial cells of Cajal was reduced throughout the tunica muscularis in comparison to control small intestines. The disturbance of intestinal motility that occurs in patients with Crohn's disease may be a consequence of the loss of or defects in specific populations of interstitial cells of Cajal within the tunica muscularis.

Depletion of interstitial oxygen in silicon and the thermal donor model

NASA Technical Reports Server (NTRS)

Borenstein, Jeffrey T.; Singh, Vijay A.; Corbett, James W.

1987-01-01

It is shown here that the experimental results of Newman (1985) and Tan et al. (1986) regarding the loss of oxygen interstitials during 450 C annealing of Czochralski silicon are consistent with the recently proposed model of Borenstein, Peak, and Corbett (1986) for thermal donor formation. Calculations were carried out for TD cores corresponding to O2, O3, O4, and/or O5 clusters. A simple model which attempts to capture the essential physics of the interstitial depletion has been constructed, and is briefly described.

Bevacizumab-induced chronic interstitial pneumonia during maintenance therapy in non-small cell lung cancer.

PubMed

Sekimoto, Yasuhito; Kato, Motoyasu; Shukuya, Takehiko; Koyama, Ryo; Nagaoka, Tetsutaro; Takahashi, Kazuhisa

2016-04-01

Bevacizumab is a monoclonal antibody targeting the vascular endothelial growth factor receptor and a key drug for advanced non-small cell lung cancer. There are few reports describing bevacizumab-induced chronic interstitial pneumonia. A 62-year-old man with advanced non-small cell lung cancer was admitted to our hospital with dyspnea. He previously received four courses of carboplatin plus paclitaxel with bevacizumab combination therapy and thereafter received four courses of maintenance bevacizumab monotherapy. A chest-computed tomography scan on admission revealed diffuse ground glass opacity. He had not received any other drugs and did not have pneumonia. Thus, he was diagnosed with bevacizumab-induced chronic interstitial pneumonia and was treated with a high dose of corticosteroids. After steroid treatment, his dyspnea and radiological findings improved. This case report is the first description of bevacizumab-induced chronic interstitial pneumonia during maintenance therapy in a patient with non-small cell lung cancer.

Recombination radius of a Frenkel pair and capture radius of a self-interstitial atom by vacancy clusters in bcc Fe

NASA Astrophysics Data System (ADS)

Nakashima, Kenichi; Stoller, Roger E.; Xu, Haixuan

2015-08-01

The recombination radius of a Frenkel pair is a fundamental parameter for the object kinetic Monte Carlo (OKMC) and mean field rate theory (RT) methods that are used to investigate irradiation damage accumulation in irradiated materials. The recombination radius in bcc Fe has been studied both experimentally and numerically, however there is no general consensus about its value. The detailed atomistic processes of recombination also remain uncertain. Values from 1.0a0 to 3.3a0 have been employed as a recombination radius in previous studies using OKMC and RT. The recombination process of a Frenkel pair is investigated at the atomic level using the self-evolved atomistic kinetic Monte Carlo (SEAKMC) method in this paper. SEAKMC calculations reveal that a self-interstitial atom recombines with a vacancy in a spontaneous reaction from several nearby sites following characteristic pathways. The recombination radius of a Frenkel pair is estimated to be 2.26a0 by taking the average of the recombination distances from 80 simulation cases. In addition, we apply these procedures to the capture radius of a self-interstitial atom by a vacancy cluster. The capture radius is found to gradually increase with the size of the vacancy cluster. The fitting curve for the capture radius is obtained as a function of the number of vacancies in the cluster.

Point defect induced segregation of alloying solutes in α-Fe

NASA Astrophysics Data System (ADS)

You, Yu-Wei; Zhang, Yange; Li, Xiangyan; Xu, Yichun; Liu, C. S.; Chen, J. L.; Luo, G.-N.

2016-10-01

Segregation of alloying solute toward clusters and precipitates can result in hardening and embrittlement of ferritic and ferritic/martensitic steels in aging nuclear power plants. Thus, it is essential to study the segregation of solute in α-Fe. In this study, the segregation of eight kinds of alloying solutes (Al, Si, P, S, Ga, Ge, As, Se) in defect-free system and at vacancy, divacancy, and self-interstitial atom in α-Fe has been systematically studied by first-principles calculations. We find that it is energetically favorable for multiple solute S or Se atoms to segregate in defect-free system to form solute clusters, whereas it is very difficult for the other solute atoms to form the similar clusters. With the presence of vacancy and divacancy, the segregation of all the solutes are significantly promoted to form vacancy-solute and divacancy-solute clusters. The divacancy-solute cluster is more stable than the vacancy-solute cluster. The most-stable self-interstitial atom 〈110〉 dumbbell is also found to tightly bind with multiple solute atoms. The 〈110〉-S is even more stable than divacancy-S cluster. Meanwhile, the law of mass action is employed to predict the concentration evolution of vacancy-Si, vacancy-P, and vacancy-S clusters versus temperature and vacancy concentration.

Primary radiation damage characterization of α-iron under irradiation temperature for various PKA energies

NASA Astrophysics Data System (ADS)

Sahi, Qurat-ul-ain; Kim, Yong-Soo

2018-04-01

The understanding of radiation-induced microstructural defects in body-centered cubic (BCC) iron is of major interest to those using advanced steel under extreme conditions in nuclear reactors. In this study, molecular dynamics (MD) simulations were implemented to examine the primary radiation damage in BCC iron with displacement cascades of energy 1, 5, 10, 20, and 30 keV at temperatures ranging from 100 to 1000 K. Statistical analysis of eight MD simulations of collision cascades were carried out along each [110], [112], [111] and a high index [135] direction and the temperature dependence of the surviving number of point defects and the in-cascade clustering of vacancies and interstitials were studied. The peak time and the corresponding number of defects increase with increasing irradiation temperature and primary knock-on atom (PKA) energy. However, the final number of surviving point defects decreases with increasing lattice temperature. This is associated with the increase of thermal spike at high PKA energy and its long timespan at higher temperatures. Defect production efficiency (i.e., surviving MD defects, per Norgett-Robinson-Torrens displacements) also showed a continuous decrease with the increasing irradiation temperature and PKA energy. The number of interstitial clusters increases with both irradiation temperature and PKA energy. However, the increase in the number of vacancy clusters with PKA energy is minimal-to-constant and decreases as the irradiation temperature increases. Similarly, the probability and cluster size distribution for larger interstitials increase with temperature, whereas only smaller size vacancy clusters were observed at higher temperatures.

The effect of primary recoil spectrum on radiation induced segregation in nickel-silicon alloys

NASA Astrophysics Data System (ADS)

Averback, R. S.; Rehn, L. E.; Wagner, W.; Ehrhart, P.

1983-08-01

Segregation of silicon to the surface of Ni-12.7 at% Si alloys during 2.0-MeV He and 3.25-MeV Kr irradiations was measured using Rutherford backscattering spectrometry. For equal calculated defect production rates the Kr irradiation was < 3 % as efficient as the He irradiation for promoting segregation in the temperature range, 450 °C-580 °C. It was further observed that Kr preirradiation of specimens dramatically reduced segregation during subsequent He irradiation. A model for cascade annealing in Ni-Si alloys is presented which qualitatively explains the segregation results. The model assumes that small interstitial-atom-clusters form in individual cascades and that these clusters become trapped at silicon solute atoms. The vacancy thereby becomes the more mobile defect. The model should also have relevance for the observation that void swelling in nickel is suppressed by the addition of silicon solute.

Recombination radius of a Frenkel pair and capture radius of a self-interstitial atom by vacancy clusters in bcc Fe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakashima, Kenichi; Stoller, Roger E.; Xu, Haixuan

The recombination radius of a Frenkel pair is a fundamental parameter for the object kinetic Monte Carlo (OKMC) and mean field rate theory (RT) methods that are used to investigate irradiation damage accumulation in neutron irradiated nuclear materials. The recombination radius in bcc Fe has been studied both experimentally and numerically, however there is no general consensus about its value. The detailed atomistic processes of recombination also remain uncertain. Values from 1:0a₀ to 3:3a₀ have been employed as a recombination radius in previous studies using OKMC and RT. The recombination process of a Frenkel pair is investigated at the atomicmore » level using the self-evolved atomistic kinetic Monte Carlo (SEAKMC) method in this paper. SEAKMC calculations reveal that a self-interstitial atom recombines with a vacancy in a spontaneous reaction from several nearby sites following characteristic pathways. The recombination radius of a Frenkel pair is estimated to be 2.26a₀ by taking the average of the recombination distances from 80 simulation cases. This value agrees well with the experimental estimate. In addition, we apply these procedures to the capture radius of a self-interstitial atom by a vacancy cluster. The capture radius is found to gradually increase with the size of the vacancy cluster. The fitting curve for the capture radius is obtained as a function of the number of vacancies in the cluster.« less

Recombination radius of a Frenkel pair and capture radius of a self-interstitial atom by vacancy clusters in bcc Fe

DOE PAGES

Nakashima, Kenichi; Stoller, Roger E.; Xu, Haixuan

2015-08-04

The recombination radius of a Frenkel pair is a fundamental parameter for the object kinetic Monte Carlo (OKMC) and mean field rate theory (RT) methods that are used to investigate irradiation damage accumulation in neutron irradiated nuclear materials. The recombination radius in bcc Fe has been studied both experimentally and numerically, however there is no general consensus about its value. The detailed atomistic processes of recombination also remain uncertain. Values from 1:0a₀ to 3:3a₀ have been employed as a recombination radius in previous studies using OKMC and RT. The recombination process of a Frenkel pair is investigated at the atomicmore » level using the self-evolved atomistic kinetic Monte Carlo (SEAKMC) method in this paper. SEAKMC calculations reveal that a self-interstitial atom recombines with a vacancy in a spontaneous reaction from several nearby sites following characteristic pathways. The recombination radius of a Frenkel pair is estimated to be 2.26a₀ by taking the average of the recombination distances from 80 simulation cases. This value agrees well with the experimental estimate. In addition, we apply these procedures to the capture radius of a self-interstitial atom by a vacancy cluster. The capture radius is found to gradually increase with the size of the vacancy cluster. The fitting curve for the capture radius is obtained as a function of the number of vacancies in the cluster.« less

Identification of Clinical Phenotypes in Idiopathic Interstitial Pneumonia with Pulmonary Emphysema.

PubMed

Sato, Suguru; Tanino, Yoshinori; Misa, Kenichi; Fukuhara, Naoko; Nikaido, Takefumi; Uematsu, Manabu; Fukuhara, Atsuro; Wang, Xintao; Ishida, Takashi; Munakata, Mitsuru

2016-01-01

Objective Since the term "combined pulmonary fibrosis and emphysema" (CPFE) was first proposed, the co-existence of pulmonary fibrosis and pulmonary emphysema (PE) has drawn considerable attention. However, conflicting results on the clinical characteristics of patients with both pulmonary fibrosis and PE have been published because of the lack of an exact definition of CPFE. The goal of this study was thus to clarify the clinical characteristics and phenotypes of idiopathic interstitial pneumonia (IIP) with PE. Methods We retrospectively analyzed IIP patients who had been admitted to our hospital. Their chest high-resolution computed tomography images were classified into two groups according to the presence of PE. We then performed a cluster analysis to identify the phenotypes of IIP patients with PE. Results Forty-four (53.7%) out of 82 patients had at least mild emphysema in their bilateral lungs. The cluster analysis separated the IIP patients with PE into three clusters. The overall survival rate of one cluster that consisted of mainly idiopathic pulmonary fibrosis (IPF) patients was significantly worse than those of the other clusters. Conclusion Three different phenotypes can be identified in IIP patients with PE, and IPF with PE is a distinct clinical phenotype with a poor prognosis.

Modeling the suppression of boron transient enhanced diffusion in silicon by substitutional carbon incorporation

NASA Astrophysics Data System (ADS)

Ngau, Julie L.; Griffin, Peter B.; Plummer, James D.

2001-08-01

Recent work has indicated that the suppression of boron transient enhanced diffusion (TED) in carbon-rich Si is caused by nonequilibrium Si point defect concentrations, specifically the undersaturation of Si self-interstitials, that result from the coupled out-diffusion of carbon interstitials via the kick-out and Frank-Turnbull reactions. This study of boron TED reduction in Si1-x-yGexCy during 750 °C inert anneals has revealed that the use of an additional reaction that further reduces the Si self-interstitial concentration is necessary to describe accurately the time evolved diffusion behavior of boron. In this article, we present a comprehensive model which includes {311} defects, boron-interstitial clusters, a carbon kick-out reaction, a carbon Frank-Turnbull reaction, and a carbon interstitial-carbon substitutional (CiCs) pairing reaction that successfully simulates carbon suppression of boron TED at 750 °C for anneal times ranging from 10 s to 60 min.

Dynamics of defect-loaded grain boundary under shear deformation in alpha iron

NASA Astrophysics Data System (ADS)

Yang, L.; Zhou, H. L.; Liu, H.; Gao, F.; Zu, X. T.; Peng, S. M.; Long, X. G.; Zhou, X. S.

2018-02-01

Two symmetric tilt grain boundaries (GBs) (Σ3〈110〉{112} and Σ11〈110〉{332}) in alpha iron were performed to investigate the dynamics of defect-loaded GBs under shear deformation. The results show that the loaded self-interstitial atoms (SIAs) reduce the critical stress of the coupled GB motion in the Σ3 GB, but increase the critical stress in the Σ11 GB. The loaded SIAs in the Σ3 GB easily form 〈111〉 clusters and remain in the bulk when the GB moves away. However, the SIAs move along with the Σ11 GB and combine with the vacancies in the bulk, leading to the defect self-healing. The helium (He) atoms loaded into the GBs significantly affect the coupled GB motion. Once He clusters emit interstitials, the Σ11 GB carries those interstitials away but the Σ3 does not. The loaded He atoms reduce the critical stress of the Σ3 GB, but increase the critical stress of the Σ11 GB.

Numerical analysis of stress effects on Frank loop evolution during irradiation in austenitic Fe&z.sbnd;Cr&z.sbnd;Ni alloy

NASA Astrophysics Data System (ADS)

Tanigawa, Hiroyasu; Katoh, Yutai; Kohyama, Akira

1995-08-01

Effects of applied stress on early stages of interstitial type Frank loop evolution were investigated by both numerical calculation and irradiation experiments. The final objective of this research is to propose a comprehensive model of complex stress effects on microstructural evolution under various conditions. In the experimental part of this work, the microstructural analysis revealed that the differences in resolved normal stress caused those in the nucleation rates of Frank loops on {111} crystallographic family planes, and that with increasing external applied stress the total nucleation rate of Frank loops was increased. A numerical calculation was carried out primarily to evaluate the validity of models of stress effects on nucleation processes of Frank loop evolution. The calculation stands on rate equuations which describe evolution of point defects, small points defect clusters and Frank loops. The rate equations of Frank loop evolution were formulated for {111} planes, considering effects of resolved normal stress to clustering processes of small point defects and growth processes of Frank loops, separately. The experimental results and the predictions from the numerical calculation qualitatively coincided well with each other.

First-principles calculations of niobium hydride formation in superconducting radio-frequency cavities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ford, Denise C.; Cooley, Lance D.; Seidman, David N.

Niobium hydride is suspected to be a major contributor to degradation of the quality factor of niobium superconducting radio-frequency (SRF) cavities. In this study, we connect the fundamental properties of hydrogen in niobium to SRF cavity performance and processing. We modeled several of the niobium hydride phases relevant to SRF cavities and present their thermodynamic, electronic, and geometric properties determined from calculations based on density-functional theory. We find that the absorption of hydrogen from the gas phase into niobium is exothermic and hydrogen becomes somewhat anionic. The absorption of hydrogen by niobium lattice vacancies is strongly preferred over absorption intomore » interstitial sites. A single vacancy can accommodate six hydrogen atoms in the symmetrically equivalent lowest-energy sites and additional hydrogen in the nearby interstitial sites affected by the strain field: this indicates that a vacancy can serve as a nucleation center for hydride phase formation. Small hydride precipitates may then occur near lattice vacancies upon cooling. Vacancy clusters and extended defects should also be enriched in hydrogen, potentially resulting in extended hydride phase regions upon cooling. We also assess the phase changes in the niobium-hydrogen system based on charge transfer between niobium and hydrogen, the strain field associated with interstitial hydrogen, and the geometry of the hydride phases. The results of this study stress the importance of not only the hydrogen content in niobium, but also the recovery state of niobium for the performance of SRF cavities.« less

Effect of post-implantation annealing on Al-N isoelectronic trap formation in silicon: Al-N pair formation and defect recovery mechanisms

NASA Astrophysics Data System (ADS)

Mori, Takahiro; Morita, Yukinori; Matsukawa, Takashi

2018-05-01

The effect of post-implantation annealing (PIA) on Al-N isoelectronic trap (IET) formation in silicon has been experimentally investigated to discuss the Al-N IET formation and implantation-induced defect recovery mechanisms. We performed a photoluminescence study, which indicated that self-interstitial clusters and accompanying vacancies are generated in the ion implantation process. It is supposed that Al and N atoms move to the vacancy sites and form stable Al-N pairs in the PIA process. Furthermore, the PIA process recovers self-interstitial clusters while transforming their atomic configuration. The critical temperature for the formation/dissociation of Al-N pairs was found to be 450 °C, with which we describe the process integration for devices utilizing Al-N IET technology.

Development of a Scanning Microscale Fast Neutron Irradiation Platform for Examining the Correlation Between Local Neutron Damage and Graphite Microstructure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pinhero, Patrick; Windes, William

2015-03-10

The fast particle radiation damage effect of graphite, a main material in current and future nuclear reactors, has significant influence on the utilization of this material in fission and fusion plants. Atoms on graphite crystals can be easily replaced or dislocated by fast protons and result in interstitials and vacancies. The currently accepted model indicates that after most of the interstitials recombine with vacancies, surviving interstitials form clusters and furthermore gather to create loops with each other between layers. Meanwhile, surviving vacancies and interstitials form dislocation loops on the layers. The growth of these inserted layers cause the dimensional increase,more » i.e. swelling, of graphite. Interstitial and vacancy dislocation loops have been reported and they can easily been observed by electron microscope. However, observation of the intermediate atom clusters becomes is paramount in helping prove this model. We utilize fast protons generated from the University of Missouri Research Reactor (MURR) cyclotron to irradiate highly- oriented pyrolytic graphite (HOPG) as target for this research. Post-irradiation examination (PIE) of dosed targets with high-resolution transmission electron microscopy (HRTEM) has permit observation and analysis of clusters and dislocation loops to support the proposed theory. Another part of the research is to validate M.I. Heggie’s Ruck and Tuck model, which introduced graphite layers may fold under fast particle irradiation. Again, we employed microscopy to image irradiated specimens to determine how the extent of Ruck and Tuck by calculating the number of folds as a function of dose. Our most significant accomplishment is the invention of a novel class of high-intensity pure beta-emitters for long-term lightweight batteries. We have filed four invention disclosure records based on the research conducted in this project. These batteries are lightweight because they consist of carbon and tritium and can be fabricated to conform to many geometric shapes. In addition, we have published eight peer-reviewed American Nuclear Society (ANS) transactions, and presented our findings at ANS National Meetings, and several universities.« less

The deep muscular plexus of the pig duodenum: a histochemical and ultrastructural study with special reference to the interstitial cells.

PubMed

Henry, M; Porcher, C; Julé, Y

1998-06-10

The aim of the present study was to describe the deep muscular plexus of the pig duodenum and to characterize its cellular components. Numerous nerve varicosities have been detected in the deep muscular plexus using anti-synaptophysin antibodies. Nerve fibres were also detected here in the outer circular muscle layer, whereas no nerve fibres were observed in the inner circular muscle layer. In the deep muscular plexus, nerve fibres projected to interstitial cells which were characterized at the ultrastructural level. The interstitial cells were of two kinds: the interstitial fibroblastic-like cells (FLC) and the interstitial dense cells (IDC), both of which were interposed between nerve fibres and smooth muscle cells. The FLC were characterized by their elongated bipolar shape, the lack of basal lamina, a well-developed endoplasmic reticulum, a Golgi apparatus, and intermediate filaments. They were closely apposed to axon terminals containing small clear synaptic vesicles and/or dense-cored vesicles. They were frequently connected to each other and to smooth muscle cells of the inner and outer circular layer by desmosomes and more rarely by gap junctions. The IDC are myoid-like cells. They had a stellate appearance and were characterized by a dense cell body, numerous caveolae, and a discontinuous basal lamina. The IDC were always closely apposed to nerve fibres and were connected to smooth muscle cells by desmosomes and small gap junctions. The present results show the unique pattern of cellular organization of the deep muscular plexus of the pig small intestine. They suggest that the interstitial cells in the deep muscular plexus are involved in the integration and transmission of nervous inputs from myenteric neurons to the inner and outer circular muscle layers. The clear-cut distinction observed here between the two types of interstitial cells (fibroblastic and myoid-like) suggests that the interstitial cells of each type may also be involved in some other specific activity, which still remains to be determined.

Atomistic simulations to characterize the influence of applied strain and PKA energy on radiation damage evolution in pure aluminum

NASA Astrophysics Data System (ADS)

Sahi, Qurat-ul-ain; Kim, Yong-Soo

2018-05-01

Knowledge of defects generation, their mobility, growth rate, and spatial distribution is the cornerstone for understanding the surface and structural evolution of a material used under irradiation conditions. In this study, molecular dynamics simulations were used to investigate the coupled effect of primary knock-on atom (PKA) energy and applied strain (uniaxial and hydrostatic) fields on primary radiation damage evolution in pure aluminum. Cascade damage simulations were carried out for PKA energy ranging between 1 and 20 keV and for applied strain values ranging between -2% and 2% at the fixed temperature of 300 K. Simulation results showed that as the atomic displacement cascade proceeds under uniaxial and hydrostatic strains, the peak and surviving number of Frenkel point defects increases with increasing tension; however, these increments were more prominent under larger volume changing deformations (hydrostatic strain). The percentage fraction of point defects that aggregate into clusters increases under tension conditions; compared to the reference conditions with no strain, these increases are around 13% and 7% for interstitials and vacancies, respectively (under 2% uniaxial strain), and 19% and 11% for interstitials and vacancies, respectively (under 2% hydrostatic strain). Clusters formed of vacancies and interstitials were both larger under tensile strain conditions, with increases in both the average and maximum cluster sizes. The rate of increase/decrease in the number of Frenkel pairs, their clustering, and their size distributions under expansion/compression strain conditions were higher for higher PKA energies. Overall, the present results suggest that strain effects should be considered carefully in radiation damage environments, specifically for conditions of low temperature and high radiation energy. Compressive strain conditions could be beneficial for materials used in nuclear reactor power systems.

Dynamics of Helium-Loaded Grain Boundaries under Shear Deformation in α-Fe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Fei; Yang, Li; Heinisch, Howard L.

2014-03-30

The defects produced in collision cascades will interact with microstructural features in materials, such as GBs and dislocations. The coupled motion of GBs under stress has been widely observed in simulations and experiments. Two symmetric tilt GBs with a common <110> tilt axis (Σ3 and Σ11) in bcc iron are used to investigate the coupled motion of GBs under shear deformation. Also, we have explored the effect of self-interstitial atoms (SIAs) loading on the GB motion, with different concentrations of interstitials randomly inserted around the GB plane. The simulation results show that the interstitial loading reduces the critical stress ofmore » the GB coupled motion for the Σ3 GB. Furthermore, the interstitials and vacancies are inserted randomly at the GB plane and at a distance of 1 nm away from the GB plane, respectively, to understand the self-healing mechanism of GBs under stress. The behavior of the defect-loaded GBs depends on the GB structure. The loaded interstitials in the Σ3 GB easily form <111> interstitial clusters that do not move along with the GB. The vacancies in the Σ3 GB impede the GB motion. However, the interstitials move along with the Σ11 GB and annihilate with vacancies when the GB moves into the vacancy-rich region, leading to the self-healing and damage recovery of the Σ11 GB.« less

Late glaucoma after interstitial keratitis.

PubMed

Grant, W M

1975-01-01

In a systematic study of 45 patients who had syphilitic interstitial keratitis early in life and, many years later, were discovered to have glaucoma, there was evidence of two different but equally common mechanisms. In one group of patients, a deep-chamber type of glaucoma was superimposed on old inflammatory changes, was characteristically refractory to medical treatment, but did well with filtering surgery. The other group of patients had reversible angle-closure glaucoma associated with anatomically small anterior segments, and typically responded well to iridectomy. The late, refractory, deep-chamber type of glaucoma may involve endothelialization and formation of glass membrane in the angle, as seen in one excised eye. Occurrence of the shallow-chamber, reversible angle-closure type of glaucoma after interstitial keratitis may be coincidental, since no other evidence supports the idea that small anterior segments might be particularly prevalent among patients who have had congenital syphilis or interstitial keratitis.

Studies of Point Defects and Defect Interactions in Metals Using Perturbed Gamma Gamma Angular Correlations

NASA Astrophysics Data System (ADS)

Shropshire, Steven Leslie

Point defects in plastically deformed Au, Pt, and Ni were studied with atomic-scale sensitivity using the perturbed gamma-gamma angular correlations (PAC) technique by monitoring formation and transformation of complexes of vacancy defects with very dilute ^{111}In/ ^{111}Cd solute probes. Three topics were investigated: (1) Production of vacancy defects during plastic deformation of Au was investigated to differentiate models of defect production. Concentrations of mono-, di-, and tri-vacancy species were measured in Au, and the ratio of mono- to di-vacancies was found to be independent of the amount of deformation. Results indicate that point defects are produced in correlated lattice locations, such as in "strings", as a consequence of dislocation interactions and not at random locations. (2) Hydrogen interactions with vacancy-solute complexes were studied in Pt. From thermal detrapping experiments, binding of hydrogen in complexes with mono-, di- and tri-vacancies was determined using a model for hydrogen diffusing in a medium with traps, with enthalpies all measured in the narrow range 0.23-0.28 eV, proving that the binding is insensitive to the precise structure of small vacancy clusters. Nuclear relaxation of the probe in a trivacancy complex in Pt was studied as a function of temperature, from which an activation energy of 0.34 eV was measured. This value is inconsistent with relaxation caused by diffusion or trapping of hydrogen, but explainable by dynamical hopping of the PAC probe atom in a cage of vacancies. (3) By observing transformations between vacancy-solute complexes induced by annihilation reactions, it was demonstrated that interstitials are produced during plastic deformation. The evolution of concentrations of the different vacancy complexes under an interstitial flux was measured and analyzed using a kinetic-rate model, from which interstitial capture cross-sections for the different vacancy complexes and the relative quantities of interstitial species in the flux were determined. Deformation of Au was found to produce only mono- and di-interstitial fluxes in a 1:2 ratio. Cross-sections increased rapidly with the number of vacancies, which is attributed to the amount of relaxation of lattice strains around solute-vacancy complexes.

Paragenesis of multiple platinum-group mineral populations in Shetland ophiolite chromitite: 3D X-ray tomography and in situ Os isotopes

NASA Astrophysics Data System (ADS)

Prichard, H. M.; Barnes, Stephen J.; Dale, C. W.; Godel, B.; Fisher, P. C.; Nowell, G. M.

2017-11-01

Chromitite from the Harold's Grave locality in the mantle section of the Shetland ophiolite complex is extremely enriched in Ru, Os and Ir, at μg/g concentrations. High-resolution X-ray computed tomography on micro-cores from these chromitites was used to determine the location, size, distribution and morphology of the platinum-group minerals (PGM). There are five generations of PGM in these chromitites. Small (average 5 μm in equivalent sphere diameter, ESD) euhedral laurites, often with Os-Ir alloys, are totally enclosed in the chromite and are likely to have formed first by direct crystallisation from the magma as the chromite crystallised. Also within the chromitite there are clusters of larger (50 μm ESD) aligned elongate crystals of Pt-, Rh-, Ir-, Os- and Ru-bearing PGM that have different orientations in different chromite crystals. These may have formed either by exsolution, or by preferential nucleation of PGMs in boundary layers around particular growing chromite grains. Thirdly there is a generation of large (100 μm ESD) composite Os-Ir-Ru-rich PGM that are all interstitial to the chromite grains and sometimes form in clusters. It is proposed that Os, Ir and Ru in this generation were concentrated in base metal sulfide droplets that were then re-dissolved into a later sulfide-undersaturated magma, leaving PGM interstitial to the chromite grains. Fourthly there is a group of almost spherical large (80 μm ESD) laurites, hosting minor Os-Ir-Ru-rich PGM that form on the edge or enclosed in chromite grains occurring in a sheet crosscutting a chromitite layer. These may be hosted in an annealed late syn- or post magmatic fracture. Finally a few of the PGM have been deformed in localised shear zones through the chromitites. The vast majority of the PGM - including small PGM enclosed within chromite, larger interstitial PGM and elongate aligned PGM - have Os isotope compositions that give Re-depletion model ages approximately equal to the age of the ophiolite at ∼492 Ma. A number of other PGM - not confined to a single textural group - fall to more or less radiogenic values, with four PGM giving anomalously unradiogenic Os corresponding to an older age of ∼1050 Ma. The 187Os/188Os isotopic ratios for PGM from Cliff and Quoys, from the same ophiolite section, are somewhat more radiogenic than those at Harold's Grave. This may be due to a distinct mantle source history or possibly the assimilation of radiogenic crustal Os.

Point defect evolution in Ni, NiFe and NiCr alloys from atomistic simulations and irradiation experiments

DOE PAGES

Aidhy, Dilpuneet S.; Lu, Chenyang; Jin, Ke; ...

2015-08-08

Using molecular dynamics simulations, we elucidate irradiation-induced point defect evolution in fcc pure Ni, Ni 0.5Fe 0.5, and Ni 0.8Cr 0.2 solid solution alloys. We find that irradiation-induced interstitials form dislocation loops that are of 1/3 <111>{111}-type, consistent with our experimental results. While the loops are formed in all the three materials, the kinetics of formation is considerably slower in NiFe and NiCr than in pure Ni, indicating that defect migration barriers and extended defect formation energies could be higher in the alloys than pure Ni. As a result, while larger size clusters are formed in pure Ni, smaller andmore » more clusters are observed in the alloys. The vacancy diffusion occurs at relatively higher temperatures than interstitials, and their clustering leads to formation of stacking fault tetrahedra, also consistent with our experiments. The results also show that the surviving Frenkel pairs are composition-dependent and are largely Ni dominated.« less

Analysis of Dissolved Organic Nutrients in the Interstitial Water of Natural Biofilms.

PubMed

Tsuchiya, Yuki; Eda, Shima; Kiriyama, Chiho; Asada, Tomoya; Morisaki, Hisao

2016-07-01

In biofilms, the matrix of extracellular polymeric substances (EPSs) retains water in the interstitial region of the EPS. This interstitial water is the ambient environment for microorganisms in the biofilms. The nutrient condition in the interstitial water may affect microbial activity in the biofilms. In the present study, we measured the concentrations of dissolved organic nutrients, i.e., saccharides and proteins, contained in the interstitial water of biofilms formed on the stones. We also analyzed the molecular weight distribution, chemical species, and availability to bacteria of some saccharides in the interstitial water. Colorimetric assays showed that the concentrations of saccharides and proteins in the biofilm interstitial water were significantly higher (ca. 750 times) than those in the surrounding lake waters (p < 0.05). Chromatographic analyses demonstrated that the saccharides in the interstitial waters were mainly of low molecular-weight saccharides such as glucose and maltose, while proteins in the interstitial water were high molecular-weight proteins (over 7000 Da). Bacterial growth and production of EPS occurred simultaneously with the decrease in the low molecular-weight saccharide concentrations when a small portion of biofilm suspension was inoculated to the collected interstitial water, suggesting that the dissolved saccharides in the interstitial water support bacterial growth and formation of biofilms.

From solid solution to cluster formation of Fe and Cr in α-Zr

NASA Astrophysics Data System (ADS)

Burr, P. A.; Wenman, M. R.; Gault, B.; Moody, M. P.; Ivermark, M.; Rushton, M. J. D.; Preuss, M.; Edwards, L.; Grimes, R. W.

2015-12-01

To understand the mechanisms by which the re-solution of Fe and Cr additions increase the corrosion rate of irradiated Zr alloys, the solubility and clustering of Fe and Cr in model binary Zr alloys was investigated using a combination of experimental and modelling techniques - atom probe tomography (APT), x-ray diffraction (XRD), thermoelectric power (TEP) and density functional theory (DFT). Cr occupies both interstitial and substitutional sites in the α-Zr lattice; Fe favours interstitial sites, and a low-symmetry site that was not previously modelled is found to be the most favourable for Fe. Lattice expansion as a function of Fe and Cr content in the α-Zr matrix deviates from Vegard's law and is strongly anisotropic for Fe additions, expanding the c-axis while contracting the a-axis. Matrix content of solutes cannot be reliably estimated from lattice parameter measurements, instead a combination of TEP and APT was employed. Defect clusters form at higher solution concentrations, which induce a smaller lattice strain compared to the dilute defects. In the presence of a Zr vacancy, all two-atom clusters are more soluble than individual point defects and as many as four Fe or three Cr atoms could be accommodated in a single Zr vacancy. The Zr vacancy is critical for the increased apparent solubility of defect clusters; the implications for irradiation induced microstructure changes in Zr alloys are discussed.

Kinetics of self-interstitial migration in bcc and fcc transition metals

NASA Astrophysics Data System (ADS)

Bukkuru, S.; Bhardwaj, U.; Srinivasa Rao, K.; Rao, A. D. P.; Warrier, M.; Valsakumar, M. C.

2018-03-01

Radiation damage is a multi-scale phenomenon. A thorough understanding of diffusivities and the migration energies of defects is a pre-requisite to quantify the after-effects of irradiation. We investigate the thermally activated mobility of self-interstitial atom (SIA) in bcc transition metals Fe, Mo, Nb and fcc transition metals Ag, Cu, Ni, Pt using molecular dynamics (MD) simulations. The self-interstitial diffusion involves various mechanisms such as interstitialcy, dumbbell or crowdion mechanisms. Max-Space Clustering (MSC) method has been employed to identify the interstitial and its configuration over a wide range of temperature. The self-interstitial diffusion is Arrhenius like, however, there is a slight deviation at high temperatures. The migration energies, pre-exponential factors of diffusion and jump-correlation factors, obtained from these simulations can be used as inputs to Monte Carlo simulations of defect transport. The jump-correlation factor shows the degree of preference of rectilinear or rotational jumps. We obtain the average jump-correlation factor of 1.4 for bcc metals and 0.44 for fcc metals. It indicates that rectilinear jumps are preferred in bcc metals and rotational jumps are preferred in fcc metals.

Short-range order in the Ca sub 1-x La sub x F sub 2+x solid solution: 1:0:3 or 1:0:4 clusters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Laval, J.P.; Abaouz, A.; Frit, B.

1989-08-01

The defect structure of the Ca{sub 1-x}La{sub x}F{sub 2+x} solid solution (0 {le} x {le} 0.38) has been examined at room temperature by powder neutron diffraction. Two kinds of (xxx) interstitial anions, whose respective numbers increase linearly with increasing dopant cation concentration, have been found: one labeled F{sup 0} (x {approx} 0.41) is a true interstitial; the other labeled F{sup {prime}{double prime}} (x {approx} 0.31) can be considered a relaxed normal anion. Two 1:0:n defect clusters are compatible, within the experimental errors, with these results: the 1:0:3 (1V{sub F}, OF{prime}, 3F{sup {double prime}}, 2 La{sup 3+}) and the 1:0:4 (1V{submore » F}, OF{prime}, 4F{sup {double prime}}, 3La{sup 3+}) clusters. Charge balance considerations and comparisons with the homologous Ca{sub 1-x}M{sub x}{sup IV}F{sub 2+2x} solid solutions (M{sup IV} = Th, U) allow us to think that the less dense 1:0:3 cluster is present for the whole domain of both kinds of solid solutions.« less

Two unrelated children with overlapping 6q25.3 deletions, motor speech disorders, and language delays.

PubMed

Peter, Beate; Lancaster, Hope; Vose, Caitlin; Fares, Amna; Schrauwen, Isabelle; Huentelman, Matthew

2017-10-01

Interstitial and terminal 6q25 deletions are associated with developmental delays, hypotonia, eye pathologies, craniofacial dysmorphologies, and structural brain anomalies. In most cases, speech and language deficits are not described in detail. We report on a case (Patient 1, age 7 years) with a de novo 6q25.3-qter deletion, 11.1 Mb long and encompassing 108 genes, and a case (Patient 2, age 5 years) with an inherited interstitial 6q25.3 deletion, located within Patient 1's deletion region and 403 kb long, the smallest 6q25 deletion reported to date. Both children have hypotonia, motor speech disorders, and expressive language delays. Patient 1's speech was characterized by childhood apraxia of speech (CAS) and dysarthria. Other findings include developmental delay, ataxic cerebral palsy, optic nerve dysplagia, and atypical brain morphologies regarding the corpus callosum and gyration patterns, a clinical profile that closely matches a previously reported case with a nearly identical deletion. Patient 2 had speech characterized by CAS and typical nonverbal processing abilities. His father, a carrier, had typical speech and language but showed difficulties with complex motor speech and hand motor tasks, similar to other adults with residual signs of CAS. The small deletion in this family contains the IGF2R-AIRN-SLC22A2-SLC22A3 gene cluster, which is associated with imprinting and maternal-specific expression of Igf2R, Slc22a2, and Slc22a3 in mice, whereas imprinting in humans is a polymorphic trait. The shared phenotypes in the two patients might be associated with the deletion of the gene cluster. © 2017 Wiley Periodicals, Inc.

Rheb/mTORC1 Signaling Promotes Kidney Fibroblast Activation and Fibrosis

PubMed Central

Jiang, Lei; Xu, Lingling; Mao, Junhua; Li, Jianzhong; Fang, Li; Zhou, Yang; Liu, Wei; He, Weichun; Zhao, Allan Zijian

2013-01-01

Ras homolog enriched in brain (Rheb) is a small GTPase that regulates cell growth, differentiation, and survival by upregulating mammalian target of rapamycin complex 1 (mTORC1) signaling. The role of Rheb/mTORC1 signaling in the activation of kidney fibroblasts and the development of kidney fibrosis remains largely unknown. In this study, we found that Rheb/mTORC1 signaling was activated in interstitial myofibroblasts from fibrotic kidneys. Treatment of rat kidney interstitial fibroblasts (NRK-49F cell line) with TGFβ1 also activated Rheb/mTORC1 signaling. Blocking Rheb/mTORC1 signaling with rapamycin or Rheb small interfering RNA abolished TGFβ1-induced fibroblast activation. In a transgenic mouse, ectopic expression of Rheb activated kidney fibroblasts. These Rheb transgenic mice exhibited increased activation of mTORC1 signaling in both kidney tubular and interstitial cells as well as progressive interstitial renal fibrosis; rapamycin inhibited these effects. Similarly, mice with fibroblast-specific deletion of Tsc1, a negative regulator of Rheb, exhibited activated mTORC1 signaling in kidney interstitial fibroblasts and increased renal fibrosis, both of which rapamycin abolished. Taken together, these results suggest that Rheb/mTORC1 signaling promotes the activation of kidney fibroblasts and contributes to the development of interstitial fibrosis, possibly providing a therapeutic target for progressive renal disease. PMID:23661807

Energy Partitioning and Impulse Dispersion in the Decorated, Tapered, Strongly Nonlinear Granular Alignment: A System with Many Potential Applications

DTIC Science & Technology

2010-03-01

finally discuss some preliminary experimental results using systems with chrome spheres and small Nitinol interstitial grains to present the... Nitinol interstitial grains to present the underlying nonlinear dynamics of this so-called decorated tapered granular alignment. We are specifically...second was the DTC setup. In this case, small Nitinol 2.38 mm diameter particles were in- troduced between the main STC particles so that NDTC=9. 53 The

Radiation-induced segregation and precipitation behaviours around cascade clusters under electron irradiation.

PubMed

Sueishi, Yuichiro; Sakaguchi, Norihito; Shibayama, Tamaki; Kinoshita, Hiroshi; Takahashi, Heishichiro

2003-01-01

We have investigated the formation of cascade clusters and structural changes in them by means of electron irradiation following ion irradiation in an austenitic stainless steel. Almost all of the cascade clusters, which were introduced by the ion irradiation, grew to form interstitial-type dislocation loops or vacancy-type stacking fault tetrahedra after electron irradiation at 623 K, whereas a few of the dot-type clusters remained in the matrix. It was possible to recognize the concentration of Ni and Si by radiation-induced segregation around the dot-type clusters. After electron irradiation at 773 K, we found that some cascade clusters became precipitates (delta-Ni2Si) due to radiation-induced precipitation. This suggests that the cascade clusters could directly become precipitation sites during irradiation.

Synthesized interstitial lung texture for use in anthropomorphic computational phantoms

NASA Astrophysics Data System (ADS)

Becchetti, Marc F.; Solomon, Justin B.; Segars, W. Paul; Samei, Ehsan

2016-04-01

A realistic model of the anatomical texture from the pulmonary interstitium was developed with the goal of extending the capability of anthropomorphic computational phantoms (e.g., XCAT, Duke University), allowing for more accurate image quality assessment. Contrast-enhanced, high dose, thorax images for a healthy patient from a clinical CT system (Discovery CT750HD, GE healthcare) with thin (0.625 mm) slices and filtered back- projection (FBP) were used to inform the model. The interstitium which gives rise to the texture was defined using 24 volumes of interest (VOIs). These VOIs were selected manually to avoid vasculature, bronchi, and bronchioles. A small scale Hessian-based line filter was applied to minimize the amount of partial-volumed supernumerary vessels and bronchioles within the VOIs. The texture in the VOIs was characterized using 8 Haralick and 13 gray-level run length features. A clustered lumpy background (CLB) model with added noise and blurring to match CT system was optimized to resemble the texture in the VOIs using a genetic algorithm with the Mahalanobis distance as a similarity metric between the texture features. The most similar CLB model was then used to generate the interstitial texture to fill the lung. The optimization improved the similarity by 45%. This will substantially enhance the capabilities of anthropomorphic computational phantoms, allowing for more realistic CT simulations.

Statistical model and first-principles simulation on concentration of HenV cluster and He bubble formation in α-Fe and W

NASA Astrophysics Data System (ADS)

Liu, Yue-Lin; Yu, Yang; Dai, Zhen-Hong

2015-01-01

Using first-principles calculations, we investigate the stabilities of He and Hen-vacancy (HenV) clusters in α-Fe and W. Vacancy formation energies are 2.08 eV in α-Fe and 3.11 eV in W, respectively. Single He in both α-Fe and W prefers to occupy the tetrahedral interstitial site. We recalculated the He solution energy considering the effect of zero-point energy (ZPE). The ZPEs of He in α-Fe and W at the tetrahedral (octahedral) interstitial site are 0.072 eV (0.031 eV) and 0.078 eV (0.034 eV), respectively. The trapping energies of single He at vacancy in α-Fe and W are -2.39 eV and -4.55 eV, respectively. By sequentially adding He into vacancy, a monovacancy trap up to 10 He atoms distributing in the vacancy vicinity. Based on the above results combined with statistical model, we evaluate the concentrations of all relevant HenV clusters as a function of He chemical potential. The critical HenV concentration is found to be ∼10-40 (atomic) at the critical temperature T = 600 K in α-Fe and T = 1600 K in W, respectively. Beyond the critical HenV concentrations, considerable HenV aggregate to form HenVm clusters. By further growing of HenVm, the HenVm clusters grow bigger resulting in the larger He bubble formation.

CENH3 morphogenesis reveals dynamic centromere associations during synaptonemal complex formation and the progression through male meiosis in hexaploid wheat.

PubMed

Sepsi, Adél; Higgins, James D; Heslop-Harrison, John S Pat; Schwarzacher, Trude

2017-01-01

During meiosis, centromeres in some species undergo a series of associations, but the processes and progression to homologous pairing is still a matter of debate. Here, we aimed to correlate meiotic centromere dynamics and early telomere behaviour to the progression of synaptonemal complex (SC) construction in hexaploid wheat (2n = 42) by triple immunolabelling of CENH3 protein marking functional centromeres, and SC proteins ASY1 (unpaired lateral elements) and ZYP1 (central elements in synapsed chromosomes). We show that single or multiple centromere associations formed in meiotic interphase undergo a progressive polarization (clustering) at the nuclear periphery in early leptotene, leading to formation of the telomere bouquet. Critically, immunolabelling shows the dynamics of these presynaptic centromere associations and a structural reorganization of the centromeric chromatin coinciding with key events of synapsis initiation from the subtelomeric regions. As short stretches of subtelomeric synapsis emerged at early zygotene, centromere clusters lost their strong polarization, gradually resolving as individual centromeres indicated by more than 21 CENH3 foci associated with unpaired lateral elements. Only following this centromere depolarization were homologous chromosome arms connected, as observed by the alignment and fusion of interstitial ZYP1 loci elongating at zygotene so synapsis at centromeres is a continuation of the interstitial synapsis. Our results thus reveal that centromere associations are a component of the timing and progression of chromosome synapsis, and the gradual release of the individual centromeres from the clusters correlates with the elongation of interstitial synapsis between the corresponding homologues. © 2016 The Authors The Plant Journal © 2016 John Wiley & Sons Ltd.

The effect of injected interstitials on void formation in self-ion irradiated nickel containing concentrated solid solution alloys

DOE PAGES

Yang, Tai-ni; Lu, Chenyang; Jin, Ke; ...

2017-02-21

Pure nickel and three nickel containing single-phase concentrated solid solution alloys (SP-CSAs) have been irradiated using 3 MeV Ni 2+ ions at 500 C to fluences of 1.5 x 10 16 and 5.0 x 10 16 cm 2. We characterized the radiation-induced voids using cross sectional transmission electron microscopy that distributions of voids and dislocation loops were presented as a function of depth. We also observed a various degree of void suppression on the tested samples and a defect clusters migration mechanism was proposed for NiCo. Furthermore, in order to sufficiently understand the defect dynamics in these SP-CSAs, the injectedmore » interstitial effect has been taken into account along with the 1-dimentional (1-D) and 3-dimentional (3-D) interstitial movement mechanisms.« less

Smoking-related interstitial lung diseases.

PubMed

Caminati, A; Graziano, P; Sverzellati, N; Harari, S

2010-12-01

In pulmonary pathology, a wide spectrum of morphological changes is related to the consequences of smoking, and recognizing them on surgical specimens and on small transbronchial biopsies represents a challenge for the pathologist. Respiratory bronchiolitis, also referred to as smoker's bronchiolitis, is a common histologic feature found in the lung tissue of cigarette smokers. When identified as the sole histopathologic finding in the clinical setting of symptomatic interstitial lung disease, a diagnosis of respiratory bronchiolitis-interstitial lung disease is made. Since smoking is recognized to cause a variety of histologic patterns encompassing respiratory bronchiolitis, respiratory bronchiolitis-interstitial lung disease, desquamative interstitial pneumonia and pulmonary Langerhans cell hystiocytosis, smoking-related interstitial lung disease may be a useful concept to keep in mind for the pathologists. The relationship of smoking with each of these entities has been largely established on the basis of epidemiologic evidence. Although they have been retained as distinct and separate conditions in various classifications of interstitial lung diseases, these entities share a number of clinical, radiologic, and pathologic features suggesting that they represent a spectrum of patterns of interstitial lung disease occurring in predisposed individuals who smoke. Evaluation of histologic features, particularly in surgical lung biopsy samples, is important in making the distinction between these disorders. However, even after tissue biopsy, it may sometimes be difficult to clearly separate these entities. Recently, respiratory bronchiolitis-interstitial lung disease with fibrosis has been described and postulated that this is a smoking-related condition distinct from fibrotic non-specific interstitial pneumonia.

Correlation of gene expression with bladder capacity in interstitial cystitis/bladder pain syndrome.

PubMed

Colaco, Marc; Koslov, David S; Keys, Tristan; Evans, Robert J; Badlani, Gopal H; Andersson, Karl-Erik; Walker, Stephen J

2014-10-01

Interstitial cystitis and bladder pain syndrome are terms used to describe a heterogeneous chronic pelvic and bladder pain disorder. Despite its significant prevalence, our understanding of disease etiology is poor. We molecularly characterized interstitial cystitis/bladder pain syndrome and determined whether there are clinical factors that correlate with gene expression. Bladder biopsies from female subjects with interstitial cystitis/bladder pain syndrome and female controls without signs of the disease were collected and divided into those with normal and low anesthetized bladder capacity, respectively. Samples then underwent RNA extraction and microarray assay. Data generated by these assays were analyzed using Omics Explorer (Qlucore, Lund, Sweden), GeneSifter® Analysis Edition 4.0 and Ingenuity® Pathway Analysis to determine similarity among samples within and between groups, and measure differentially expressed transcripts unique to each phenotype. A total of 16 subjects were included in study. Principal component analysis and unsupervised hierarchical clustering showed clear separation between gene expression in tissues from subjects with low compared to normal bladder capacity. Gene expression in tissue from patients with interstitial cystitis/bladder pain syndrome who had normal bladder capacity did not significantly differ from that in controls without interstitial cystitis/bladder pain syndrome. Pairwise analysis revealed that pathways related to inflammatory and immune response were most involved. Microarray analysis provides insight into the potential pathological condition underlying interstitial cystitis/bladder pain syndrome. This pilot study shows that patients with this disorder who have low compared to normal bladder capacity have significantly different molecular characteristics, which may reflect a difference in disease pathophysiology. Copyright © 2014 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

Effects of hydration on steric and electric charge-induced interstitial volume exclusion--a model.

PubMed

Øien, Alf H; Justad, Sigrid R; Tenstad, Olav; Wiig, Helge

2013-09-03

The presence of collagen and charged macromolecules like glycosaminoglycans (GAGs) in the interstitial space limits the space available for plasma proteins and other macromolecules. This phenomenon, known as interstitial exclusion, is of importance for interstitial fluid volume regulation. Physical/mathematical models are presented for calculating the exclusion of electrically charged and neutral macromolecules that equilibrate in the interstitium under various degrees of hydration. Here, a central hypothesis is that the swelling of highly electrically charged GAGs with increased hydration shields parts of the neutral collagen of the interstitial matrix from interacting with electrically charged macromolecules, such that exclusion of charged macromolecules exhibits change due to steric and charge effects. GAGs are also thought to allow relatively small neutral, but also charged macromolecules neutralized by a very high ionic strength, diffuse into the interior of GAGs, whereas larger macromolecules may not. Thus, in the model, relatively small electrically charged macromolecules, such as human serum albumin, and larger neutral macromolecules such as IgG, will have quite similar total volume exclusion properties in the interstitium. Our results are in agreement with ex vivo and in vivo experiments, and suggest that the charge of GAGs or macromolecular drugs may be targeted to increase the tissue uptake of macromolecular therapeutic agents. Copyright © 2013 Biophysical Society. Published by Elsevier Inc. All rights reserved.

The energy and stability of helium-related cluster in nickel: A study of molecular dynamics simulation

NASA Astrophysics Data System (ADS)

Gong, Hengfeng; Wang, Chengbin; Zhang, Wei; Xu, Jian; Huai, Ping; Deng, Huiqiu; Hu, Wangyu

2016-02-01

Using molecular dynamics simulation, we investigated the energy and stability of helium-related cluster in nickel. All the binding energies of the He-related clusters are demonstrated to be positive and increase with the cluster sizes. Due to the pre-existed self-interstitial nickel atom, the trapping capability of vacancy to defects becomes weak. Besides, the minimum energy configurations of He-related clusters exhibit the very high symmetry in the local atomistic environment. And for the HeN and HeNV1SIA1 clusters, the average length of He-He bonds shortens, but it elongates for the HeNV1 clusters with helium cluster sizes. The helium-to-vacancy ratio plays a decisive role on the binding energies of HeNVM cluster. These results can provide some excellent clues to insight the initial stage of helium bubbles nucleation and growth in the Ni-based alloys for the Generation-IV Molten Salt Reactor.

Interstitial loop transformations in FeCr

DOE PAGES

Béland, Laurent Karim; Osetsky, Yuri N.; Stoller, Roger E.; ...

2015-03-27

Here, we improve the Self-Evolving Atomistic Kinetic Monte Carlo (SEAKMC) algorithm by integrating the Activation Relaxation Technique nouveau (ARTn), a powerful open-ended saddle-point search method, into the algorithm. We use it to investigate the reaction of 37-interstitial 1/2[1 1 1] and 1/2[View the MathML source] loops in FeCr at 10 at.% Cr. They transform into 1/2[1 1 1], 1/2[View the MathML source], [1 0 0] and [0 1 0] 74-interstitial clusters with an overall barrier of 0.85 eV. We find that Cr decoration locally inhibits the rotation of crowdions, which dictates the final loop orientation. Moreover, the final loop orientationmore » depends on the details of the Cr decoration. Generally, a region of a given orientation is favored if Cr near its interface with a region of another orientation is able to inhibit reorientation at this interface more than the Cr present at the other interfaces. Also, we find that substitutional Cr atoms can diffuse from energetically unfavorable to energetically favorable sites within the interlocked 37-interstitial loops conformation with barriers of less than 0.35 eV.« less

Severe acute interstitial lung disease in a patient with anaplastic lymphoma kinase rearrangement-positive non-small cell lung cancer treated with alectinib.

PubMed

Yamamoto, Yuzo; Okamoto, Isamu; Otsubo, Kohei; Iwama, Eiji; Hamada, Naoki; Harada, Taishi; Takayama, Koichi; Nakanishi, Yoichi

2015-10-01

Alectinib, the second generation anaplastic lymphoma kinase (ALK) inhibitor, has significant potency in patients with ALK rearrangement positive non-small cell lung cancer (NSCLC), and its toxicity is generally well tolerable. We report a patient who developed severe acute interstitial lung disease after alectinib treatment. An 86-year-old woman with stage IV lung adenocarcinoma positive for rearrangement of ALK gene was treated with alectinib. On the 215th day after initiation of alectinib administration, she was admitted to our hospital with the symptom of progressive dyspnea. Computed tomography (CT) revealed diffuse ground glass opacities and consolidations in both lungs, and analysis of bronchoalveolar lavage fluid revealed pronounced lymphocytosis. There was no evidence of infection or other specific causes of her condition, and she was therefore diagnosed with interstitial lung disease induced by alectinib. Her CT findings and respiratory condition improved after steroid pulse therapy. As far as we are aware, this is the first reported case of alectinib-induced severe interstitial lung disease (ILD). We should be aware of the possibility of such a severe adverse event and should therefore carefully monitor patients treated with this drug.

Small supernumerary marker chromosome derived from proximal p-arm of chromosome 2: identification by fluorescent in situ hybridization.

PubMed

Lasan Trcić, Ruzica; Hitrec, Vlasta; Letica, Ljiljana; Cuk, Mario; Begović, Davor

2003-08-01

Conventional cytogenetics detected an interstitial deletion of proximal region of p-arm of chromosome 2 in a 6-month-old boy with a phenotype slightly resembling Down's syndrome. The deletion was inherited from the father, whose karyotype revealed a small ring-shaped marker chromosome, in addition to interstitial deletion. Fluorescence in situ hybridization identified the marker, which consisted of the proximal region of the p-arm of chromosome 2, including a part of its centromere. This case shows that molecular cytogenetic analysis can reveal the mechanism of the formation of the marker chromosome.

Report on simulation of fission gas and fission product diffusion in UO 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andersson, Anders David; Perriot, Romain Thibault; Pastore, Giovanni

2016-07-22

In UO 2 nuclear fuel, the retention and release of fission gas atoms such as xenon (Xe) are important for nuclear fuel performance by, for example, reducing the fuel thermal conductivity, causing fuel swelling that leads to mechanical interaction with the clad, increasing the plenum pressure and reducing the fuel–clad gap thermal conductivity. We use multi-­scale simulations to determine fission gas diffusion mechanisms as well as the corresponding rates in UO 2 under both intrinsic and irradiation conditions. In addition to Xe and Kr, the fission products Zr, Ru, Ce, Y, La, Sr and Ba have been investigated. Density functionalmore » theory (DFT) calculations are used to study formation, binding and migration energies of small clusters of Xe atoms and vacancies. Empirical potential calculations enable us to determine the corresponding entropies and attempt frequencies for migration as well as investigate the properties of large clusters or small fission gas bubbles. A continuum reaction-­diffusion model is developed for Xe and point defects based on the mechanisms and rates obtained from atomistic simulations. Effective fission gas diffusivities are then obtained by solving this set of equations for different chemical and irradiation conditions using the MARMOT phase field code. The predictions are compared to available experimental data. The importance of the large Xe U3O cluster (a Xe atom in a uranium + oxygen vacancy trap site with two bound uranium vacancies) is emphasized, which is a consequence of its high mobility and high binding energy. We find that the Xe U3O cluster gives Xe diffusion coefficients that are higher for intrinsic conditions than under irradiation over a wide range of temperatures. Under irradiation the fast-­moving Xe U3O cluster recombines quickly with irradiation-induced interstitial U ions, while this mechanism is less important for intrinsic conditions. The net result is higher concentration of the Xe U3O cluster for intrinsic conditions than under irradiation. We speculate that differences in the irradiation conditions and their impact on the Xe U3O cluster can explain the wide range of diffusivities reported in experimental studies. However, all vacancy-­mediated mechanisms underestimate the Xe diffusivity compared to the empirical radiation-­enhanced rate used in most fission gas release models. We investigate the possibility that diffusion of small fission gas bubbles or extended Xe-­vacancy clusters may give rise to the observed radiation-­enhanced diffusion coefficient. These studies highlight the importance of U divacancies and an octahedron coordination of uranium vacancies encompassing a Xe fission gas atom. The latter cluster can migrate via a multistep mechanism with a rather low effective barrier, which together with irradiation-induced clusters of uranium vacancies, gives rise to the irradiation-enhanced diffusion coefficient observed in experiments.« less

Quantifying macropore recharge: Examples from a semi-arid area

USGS Publications Warehouse

Wood, W.W.; Rainwater, Ken A.; Thompson, D.B.

1997-01-01

The purpose of this paper is to illustrate the significantly increased resolution of determining macropore recharge by combining physical, chemical, and isotopic methods of analysis. Techniques for quantifying macropore recharge were developed for both small-scale (1 to 10 km2) and regional-scale areas in and semi-arid areas. The Southern High Plains region of Texas and New Mexico was used as a representative field site to test these methods. Macropore recharge in small-scale areas is considered to be the difference between total recharge through floors of topographically dosed basins and interstitial recharge through the same area. On the regional scale, macropore recharge was considered to be the difference between regional average annual recharge and interstitial recharge measured in the unsaturated zone. Stable isotopic composition of ground water and precipitation was used us an independent estimate of macropore recharge on the regional scale. Results of this analysis suggest that in the Southern High Plains recharge flux through macropores is between 60 and 80 percent of the total 11 mm/y. Between 15 and 35 percent of the recharge occurs by interstitial recharge through the basin floors. Approximately 5 percent of the total recharge occurs as either interstitial or matrix recharge between the basin floors, representing approximately 95 percent of the area. The approach is applicable to other arid and semi-arid areas that focus rainfall into depressions or valleys.The purpose of this paper is to illustrate the significantly increased resolution of determining macropore recharge by combining physical, chemical, and isotopic methods of analysis. Techniques for quantifying macropore recharge were developed for both small-scale (1 to 10 km2) and regional-scale areas in arid and semi-arid areas. The Southern High Plains region of Texas and New Mexico was used as a representative field site to test these methods. Macropore recharge in small-scale areas is considered to be the difference between total recharge through floors of topographically closed basins and interstitial recharge through the same area. On the regional scale, macropore recharge was considered to be the difference between regional average annual recharge and interstitial recharge measured in the unsaturated zone. Stable isotopic composition of ground water and precipitation was used as an independent estimate of macropore recharge on the regional scale. Results of this analysis suggest that in the Southern High Plains recharge flux through macropores is between 60 and 80 percent of the total 11 mm/y. Between 15 and 35 percent of the recharge occurs by interstitial recharge through the basin floors. Approximately 5 percent of the total recharge occurs as either interstitial or matrix recharge between the basin floors, representing approximately 95 percent of the area. The approach is applicable to other arid and semi-arid areas that focus rainfall into depressions or valleys.

Effect of nickel on point defects diffusion in Fe – Ni alloys

DOE PAGES

Anento, Napoleon; Serra, Anna; Osetsky, Yury N.

2017-05-05

Iron-Nickel alloys are perspective alloys as nuclear energy structural materials because of their good radiation damage tolerance and mechanical properties. Understanding of experimentally observed features such as the effect of Ni content to radiation defects evolution is essential for developing predictive models of radiation. Recently an atomic-scale modelling study has revealed one particular mechanism of Ni effect related to the reduced mobility of clusters of interstitial atoms in Fe-Ni alloys. In this paper we present results of the microsecond-scale molecular dynamics study of point defects, i.e. vacancies and self-interstitial atoms, diffusion in Fe-Ni alloys. It is found that the additionmore » of Ni atoms affects diffusion processes: diffusion of vacancies is enhanced in the presence of Ni, whereas diffusion of interstitials is reduced and these effects increase at high Ni concentration and low temperature. As a result, the role of Ni solutes in radiation damage evolution in Fe-Ni alloys is discussed.« less

Interstitial pneumonitis after acetylene welding: a case report.

PubMed

Brvar, Miran

2014-01-01

Acetylene is a colorless gas commonly used for welding. It acts mainly as a simple asphyxiant. In this paper, however, we present a patient who developed a severe interstitial pneumonitis after acetylene exposure during aluminum welding. A 44-year old man was welding with acetylene, argon and aluminum electrode sticks in a non-ventilated aluminum tank for 2 h. Four hours after welding dyspnea appeared and 22 h later he was admitted at the Emergency Department due to severe respiratory insufficiency with pO2 = 6.7 kPa. Chest X-ray showed diffuse interstitial infiltration. Pulmonary function and gas diffusion tests revealed a severe restriction (55% of predictive volume) and impaired diffusion capacity (47% of predicted capacity). Toxic interstitial pneumonitis was diagnosed and high-dose systemic corticosteroid methylprednisolone and inhalatory corticosteroid fluticasone therapy was started. Computed Tomography (CT) of the lungs showed a diffuse patchy ground-glass opacity with no signs of small airway disease associated with interstitial pneumonitis. Corticosteroid therapy was continued for the next 8 weeks gradually reducing the doses. The patient's follow-up did not show any deterioration of respiratory function. In conclusion, acetylene welding might result in severe toxic interstitial pneumonitis that improves after an early systemic and inhalatory corticosteroid therapy.

Ground-state geometries and stability of impurity doped clusters: LinBe and LinMg (n=1-12)

NASA Astrophysics Data System (ADS)

Deshpande, M.; Dhavale, A.; Zope, R. R.; Chacko, S.; Kanhere, D. G.

2000-12-01

We have investigated the ground-state geometries of LinBe and LinMg (n=1-12) clusters using ab initio molecular dynamics. These divalent impurities Be and Mg induce different geometries and follow a different growth path for n>5. LinMg clusters are significantly different from the host geometries while LinBe clusters can be approximately viewed as Be occupying an interstitial site in the host. Our results indicate that Be gets trapped inside the Li cage, while Mg remains on the surface of the cluster. Mg-induced geometries become three-dimensional earlier at n=4 as compared to the Be system. In spite of a distinct arrangement of atoms in both cases the character of the wave functions in the d manifold is remarkably similar. In both cases an eight valence electron system has been found to be the most stable, in conformity with the spherical jellium model.

Impact of Interstitial Ni on the Thermoelectric Properties of the Half-Heusler TiNiSn.

PubMed

Barczak, Sonia A; Buckman, Jim; Smith, Ronald I; Baker, Annabelle R; Don, Eric; Forbes, Ian; Bos, Jan-Willem G

2018-03-30

TiNiSn is an intensively studied half-Heusler alloy that shows great potential for waste heat recovery. Here, we report on the structures and thermoelectric properties of a series of metal-rich TiNi 1+y Sn compositions prepared via solid-state reactions and hot pressing. A general relation between the amount of interstitial Ni and lattice parameter is determined from neutron powder diffraction. High-resolution synchrotron X-ray powder diffraction reveals the occurrence of strain broadening upon hot pressing, which is attributed to the metastable arrangement of interstitial Ni. Hall measurements confirm that interstitial Ni causes weak n-type doping and a reduction in carrier mobility, which limits the power factor to 2.5-3 mW m -1 K -2 for these samples. The thermal conductivity was modelled within the Callaway approximation and is quantitively linked to the amount of interstitial Ni, resulting in a predicted value of 12.7 W m -1 K -1 at 323 K for stoichiometric TiNiSn. Interstitial Ni leads to a reduction of the thermal band gap and moves the peak ZT = 0.4 to lower temperatures, thus offering the possibility to engineer a broad ZT plateau. This work adds further insight into the impact of small amounts of interstitial Ni on the thermal and electrical transport of TiNiSn.

Impact of Interstitial Ni on the Thermoelectric Properties of the Half-Heusler TiNiSn

PubMed Central

Barczak, Sonia A.; Smith, Ronald I.; Baker, Annabelle R.; Don, Eric; Forbes, Ian

2018-01-01

TiNiSn is an intensively studied half-Heusler alloy that shows great potential for waste heat recovery. Here, we report on the structures and thermoelectric properties of a series of metal-rich TiNi1+ySn compositions prepared via solid-state reactions and hot pressing. A general relation between the amount of interstitial Ni and lattice parameter is determined from neutron powder diffraction. High-resolution synchrotron X-ray powder diffraction reveals the occurrence of strain broadening upon hot pressing, which is attributed to the metastable arrangement of interstitial Ni. Hall measurements confirm that interstitial Ni causes weak n-type doping and a reduction in carrier mobility, which limits the power factor to 2.5–3 mW m−1 K−2 for these samples. The thermal conductivity was modelled within the Callaway approximation and is quantitively linked to the amount of interstitial Ni, resulting in a predicted value of 12.7 W m−1 K−1 at 323 K for stoichiometric TiNiSn. Interstitial Ni leads to a reduction of the thermal band gap and moves the peak ZT = 0.4 to lower temperatures, thus offering the possibility to engineer a broad ZT plateau. This work adds further insight into the impact of small amounts of interstitial Ni on the thermal and electrical transport of TiNiSn. PMID:29601547

Computational Modeling of Radiation Phenomenon in SiC for Nuclear Applications

NASA Astrophysics Data System (ADS)

Ko, Hyunseok

Silicon carbide (SiC) material has been investigated for promising nuclear materials owing to its superior thermo-mechanical properties, and low neutron cross-section. While the interest in SiC has been increasing, the lack of fundamental understanding in many radiation phenomena is an important issue. More specifically, these phenomena in SiC include the fission gas transport, radiation induced defects and its evolution, radiation effects on the mechanical stability, matrix brittleness of SiC composites, and low thermal conductivities of SiC composites. To better design SiC and SiC composite materials for various nuclear applications, understanding each phenomenon and its significance under specific reactor conditions is important. In this thesis, we used various modeling approaches to understand the fundamental radiation phenomena in SiC for nuclear applications in three aspects: (a) fission product diffusion through SiC, (b) optimization of thermodynamic stable self-interstitial atom clusters, (c) interface effect in SiC composite and their change upon radiation. In (a) fission product transport work, we proposed that Ag/Cs diffusion in high energy grain boundaries may be the upper boundary in unirradiated SiC at relevant temperature, and radiation enhanced diffusion is responsible for fast diffusion measured in post-irradiated fuel particles. For (b) the self-interstitial cluster work, thermodynamically stable clusters are identified as a function of cluster size, shape, and compositions using a genetic algorithm. We found that there are compositional and configurational transitions for stable clusters as the cluster size increases. For (c) the interface effect in SiC composite, we investigated recently proposed interface, which is CNT reinforced SiC composite. The analytical model suggests that CNT/SiC composites have attractive mechanical and thermal properties, and these fortify the argument that SiC composites are good candidate materials for the cladding. We used grand canonical monte carlo to optimize the interface, as a part of the stepping stone for further study using the interface.

An Effective Histological Staining Process to Visualize Bone Interstitial Fluid Space Using Confocal Microscopy

PubMed Central

Ciani, Cesare; Doty, Stephen B.; Fritton, Susannah P.

2009-01-01

Bone is a composite porous material with two functional levels of porosity: the vascular porosity that surrounds blood vessels and the lacunar-canalicular porosity that surrounds the osteocytes. Both the vascular porosity and lacunar-canalicular porosity are directly involved in interstitial fluid flow, thought to play an important role in bone’s maintenance. Because of the small dimensions of the lacunar-canalicular porosity, interstitial fluid space has been difficult to visualize and quantify. We report a new staining protocol that is reliable and easily reproducible, using fluorescein isothiocyanate (FITC) as a probe visualized by confocal microscopy. Reconstructed FITC-stained cross sections enable effective visualization of bone microstructure and microporosities. This new staining process can be used to analyze interstitial fluid space, providing high-resolution quantification of the vascular pores and the lacunar-canalicular network of cortical and cancellous bone. PMID:19442607

Kinetic Monte Carlo Simulation of Oxygen Diffusion in Ytterbium Disilicate

NASA Technical Reports Server (NTRS)

Good, Brian S.

2015-01-01

Ytterbium disilicate is of interest as a potential environmental barrier coating for aerospace applications, notably for use in next generation jet turbine engines. In such applications, the transport of oxygen and water vapor through these coatings to the ceramic substrate is undesirable if high temperature oxidation is to be avoided. In an effort to understand the diffusion process in these materials, we have performed kinetic Monte Carlo simulations of vacancy-mediated and interstitial oxygen diffusion in Ytterbium disilicate. Oxygen vacancy and interstitial site energies, vacancy and interstitial formation energies, and migration barrier energies were computed using Density Functional Theory. We have found that, in the case of vacancy-mediated diffusion, many potential diffusion paths involve large barrier energies, but some paths have barrier energies smaller than one electron volt. However, computed vacancy formation energies suggest that the intrinsic vacancy concentration is small. In the case of interstitial diffusion, migration barrier energies are typically around one electron volt, but the interstitial defect formation energies are positive, with the result that the disilicate is unlikely to exhibit experience significant oxygen permeability except at very high temperature.

Reversal of a Neurospora Translocation by Crossing over Involving Displaced Rdna, and Methylation of the Rdna Segments That Result from Recombination

PubMed Central

Perkins, David D.; Metzenberg, Robert L.; Raju, Namboori B.; Selker, Eric U.; Barry, Edward G.

1986-01-01

In translocation OY321 of Neurospora crassa, the nucleolus organizer is divided into two segments, a proximal portion located interstitially in one interchange chromosome, and a distal portion now located terminally on another chromosome, linkage group I. In crosses of Translocation x Translocation, exceptional progeny are recovered nonselectively in which the chromosome sequence has apparently reverted to Normal. Genetic, cytological, and molecular evidence indicates that reversion is the result of meiotic crossing over between homologous displaced rDNA repeats. Marker linkages are wild type in these exceptional progeny. They differ from wild type, however, in retaining an interstitial block of rRNA genes which can be demonstrated cytologically by the presence of a second, small interstitial nucleolus and genetically by linkage of an rDNA restriction site polymorphism to the mating-type locus in linkage group I. The interstitial rDNA is more highly methylated than the terminal rDNA. The mechanism by which methylation enzymes distinguish between interstitial rDNA and terminal rDNA is unknown. Some hypotheses are considered. PMID:2947829

The effect of interstitial pressure on tumor growth: coupling with the blood and lymphatic vascular systems

PubMed Central

Wu, Min; Frieboes, Hermann B.; McDougall, Steven R.; Chaplain, Mark A.J.; Cristini, Vittorio; Lowengrub, John

2013-01-01

The flow of interstitial fluid and the associated interstitial fluid pressure (IFP) in solid tumors and surrounding host tissues have been identified as critical elements in cancer growth and vascularization. Both experimental and theoretical studies have shown that tumors may present elevated IFP, which can be a formidable physical barrier for delivery of cell nutrients and small molecules into the tumor. Elevated IFP may also exacerbate gradients of biochemical signals such as angiogenic factors released by tumors into the surrounding tissues. These studies have helped to understand both biochemical signaling and treatment prognosis. Building upon previous work, here we develop a vascular tumor growth model by coupling a continuous growth model with a discrete angiogenesis model. We include fluid/oxygen extravasation as well as a continuous lymphatic field, and study the micro-environmental fluid dynamics and their effect on tumor growth by accounting for blood flow, transcapillary fluid flux, interstitial fluid flow, and lymphatic drainage. We thus elucidate further the non-trivial relationship between the key elements contributing to the effects of interstitial pressure in solid tumors. In particular, we study the effect of IFP on oxygen extravasation and show that small blood/lymphatic vessel resistance and collapse may contribute to lower transcapillary fluid/oxygen flux, thus decreasing the rate of tumor growth. We also investigate the effect of tumor vascular pathologies, including elevated vascular and interstitial hydraulic conductivities inside the tumor as well as diminished osmotic pressure differences, on the fluid flow across the tumor capillary bed, the lymphatic drainage, and the IFP. Our results reveal that elevated interstitial hydraulic conductivity together with poor lymphatic function is the root cause of the development of plateau profiles of the IFP in the tumor, which have been observed in experiments, and contributes to a more uniform distribution of oxygen, solid tumor pressure and a broad-based collapse of the tumor lymphatics. We also find that the rate that IFF is fluxed into the lymphatics and host tissue is largely controlled by an elevated vascular hydraulic conductivity in the tumor. We discuss the implications of these results on microenvironmental transport barriers, and the tumor invasive and metastatic potential. Our results suggest the possibility of developing strategies of targeting tumor cells based on the cues in the interstitial fluid. PMID:23220211

A tungsten-rhenium interatomic potential for point defect studies

DOE PAGES

Setyawan, Wahyu; Gao, Ning; Kurtz, Richard J.

2018-05-28

A tungsten-rhenium (W-Re) classical interatomic potential is developed within the embedded atom method (EAM) interaction framework. A force-matching method is employed to fit the potential to ab initio forces, energies, and stresses. Simulated annealing is combined with the conjugate gradient technique to search for an optimum potential from over 1000 initial trial sets. The potential is designed for studying point defects in W-Re systems. It gives good predictions of the formation energies of Re defects in W and the binding energies of W self-interstitial clusters with Re. The potential is further evaluated for describing the formation energy of structures inmore » the σ and χ intermetallic phases. The predicted convex-hulls of formation energy are in excellent agreement with ab initio data. In pure Re, the potential can reproduce the formation energies of vacancy and self-interstitial defects sufficiently accurately, and gives the correct ground state self-interstitial configuration. Furthermore, by including liquid structures in the fit, the potential yields a Re melting temperature (3130 K) that is close to the experimental value (3459 K).« less

A tungsten-rhenium interatomic potential for point defect studies

NASA Astrophysics Data System (ADS)

Setyawan, Wahyu; Gao, Ning; Kurtz, Richard J.

2018-05-01

A tungsten-rhenium (W-Re) classical interatomic potential is developed within the embedded atom method interaction framework. A force-matching method is employed to fit the potential to ab initio forces, energies, and stresses. Simulated annealing is combined with the conjugate gradient technique to search for an optimum potential from over 1000 initial trial sets. The potential is designed for studying point defects in W-Re systems. It gives good predictions of the formation energies of Re defects in W and the binding energies of W self-interstitial clusters with Re. The potential is further evaluated for describing the formation energy of structures in the σ and χ intermetallic phases. The predicted convex-hulls of formation energy are in excellent agreement with ab initio data. In pure Re, the potential can reproduce the formation energies of vacancies and self-interstitial defects sufficiently accurately and gives the correct ground state self-interstitial configuration. Furthermore, by including liquid structures in the fit, the potential yields a Re melting temperature (3130 K) that is close to the experimental value (3459 K).

A tungsten-rhenium interatomic potential for point defect studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Setyawan, Wahyu; Gao, Ning; Kurtz, Richard J.

A tungsten-rhenium (W-Re) classical interatomic potential is developed within the embedded atom method (EAM) interaction framework. A force-matching method is employed to fit the potential to ab initio forces, energies, and stresses. Simulated annealing is combined with the conjugate gradient technique to search for an optimum potential from over 1000 initial trial sets. The potential is designed for studying point defects in W-Re systems. It gives good predictions of the formation energies of Re defects in W and the binding energies of W self-interstitial clusters with Re. The potential is further evaluated for describing the formation energy of structures inmore » the σ and χ intermetallic phases. The predicted convex-hulls of formation energy are in excellent agreement with ab initio data. In pure Re, the potential can reproduce the formation energies of vacancy and self-interstitial defects sufficiently accurately, and gives the correct ground state self-interstitial configuration. Furthermore, by including liquid structures in the fit, the potential yields a Re melting temperature (3130 K) that is close to the experimental value (3459 K).« less

The stability of vacancy clusters and their effect on helium behaviors in 3C-SiC

NASA Astrophysics Data System (ADS)

Sun, Jingjing; Li, B. S.; You, Yu-Wei; Hou, Jie; Xu, Yichun; Liu, C. S.; Fang, Q. F.; Wang, Z. G.

2018-05-01

We have carried out systematical ab initio calculations to study the stability of vacancy clusters and their effect on helium behaviors in 3C-SiC. It is found that the formation energies of vacancy clusters containing only carbon vacancies are the lowest although the vacancies are not closest to each other, while the binding energies of vacancy clusters composed of both silicon and carbon vacancies in the closest neighbors to each other are the highest. Vacancy clusters can provide with free space for helium atoms to aggregate, while interstitial sites are not favorable for helium atoms to accumulate. The binding energies of vacancy clusters with helium atoms increase almost linearly with the ratio of helium to vacancy, n/m. The binding strength of vacancy cluster having the participation of the silicon vacancy with helium is relatively stronger than that without silicon vacancy. The vacancy clusters with more vacancies can trap helium atoms more tightly. With the presence of vacancy clusters in the material, the diffusivity of helium will be significantly reduced. Moreover, the three-dimension electron density is calculated to analyze the interplay of vacancy clusters with helium.

Direct Observation of Defect Range and Evolution in Ion-Irradiated Single Crystalline Ni and Ni Binary Alloys.

PubMed

Lu, Chenyang; Jin, Ke; Béland, Laurent K; Zhang, Feifei; Yang, Taini; Qiao, Liang; Zhang, Yanwen; Bei, Hongbin; Christen, Hans M; Stoller, Roger E; Wang, Lumin

2016-02-01

Energetic ions have been widely used to evaluate the irradiation tolerance of structural materials for nuclear power applications and to modify material properties. It is important to understand the defect production, annihilation and migration mechanisms during and after collision cascades. In this study, single crystalline pure nickel metal and single-phase concentrated solid solution alloys of 50%Ni50%Co (NiCo) and 50%Ni50%Fe (NiFe) without apparent preexisting defect sinks were employed to study defect dynamics under ion irradiation. Both cross-sectional transmission electron microscopy characterization (TEM) and Rutherford backscattering spectrometry channeling (RBS-C) spectra show that the range of radiation-induced defect clusters far exceed the theoretically predicted depth in all materials after high-dose irradiation. Defects in nickel migrate faster than in NiCo and NiFe. Both vacancy-type stacking fault tetrahedra (SFT) and interstitial loops coexist in the same region, which is consistent with molecular dynamics simulations. Kinetic activation relaxation technique (k-ART) simulations for nickel showed that small vacancy clusters, such as di-vacancies and tri-vacancies, created by collision cascades are highly mobile, even at room temperature. The slower migration of defects in the alloy along with more localized energy dissipation of the displacement cascade may lead to enhanced radiation tolerance.

Features of primary damage by high energy displacement cascades in concentrated Ni-based alloys

DOE PAGES

Béland, Laurent Karim; Lu, Chenyang; Osetskiy, Yuri N.; ...

2016-02-25

Alloying of Ni with Fe or Co reduces primary damage production under ion irradiation. Similar results have been obtained from classical molecular dynamics simulations of 1, 10, 20, and 40 keV collision cascades in Ni, NiFe, and NiCo. In all cases, a mix of imperfect stacking fault tetrahedra, faulted loops with a 1/3 {111} Burgers vector, and glissile interstitial loops with a 1/2 {110} Burgers vector were formed, along with small sessile point defect complexes and clusters. Primary damage reduction occurs by three mechanisms. First, Ni-Co, Ni-Fe, Co-Co, and Fe-Fe short-distance repulsive interactions are stiffer than Ni-Ni interactions, which leadmore » to a decrease in damage formation during the transition from the supersonic ballistic regime to the sonic regime. This largely controls final defect production. Second, alloying decreases thermal conductivity, leading to a longer thermal spike lifetime. The associated annealing reduces final damage production. These two mechanisms are especially important at cascades energies less than 40 keV. Third, at the higher energies, the production of large defect clusters by subcascades is inhibited in the alloys. A number of challenges and limitations pertaining to predictive atomistic modeling of alloys under high-energy particle irradiation are discussed.« less

Direct Observation of Defect Range and Evolution in Ion-Irradiated Single Crystalline Ni and Ni Binary Alloys

PubMed Central

Lu, Chenyang; Jin, Ke; Béland, Laurent K.; Zhang, Feifei; Yang, Taini; Qiao, Liang; Zhang, Yanwen; Bei, Hongbin; Christen, Hans M.; Stoller, Roger E.; Wang, Lumin

2016-01-01

Energetic ions have been widely used to evaluate the irradiation tolerance of structural materials for nuclear power applications and to modify material properties. It is important to understand the defect production, annihilation and migration mechanisms during and after collision cascades. In this study, single crystalline pure nickel metal and single-phase concentrated solid solution alloys of 50%Ni50%Co (NiCo) and 50%Ni50%Fe (NiFe) without apparent preexisting defect sinks were employed to study defect dynamics under ion irradiation. Both cross-sectional transmission electron microscopy characterization (TEM) and Rutherford backscattering spectrometry channeling (RBS-C) spectra show that the range of radiation-induced defect clusters far exceed the theoretically predicted depth in all materials after high-dose irradiation. Defects in nickel migrate faster than in NiCo and NiFe. Both vacancy-type stacking fault tetrahedra (SFT) and interstitial loops coexist in the same region, which is consistent with molecular dynamics simulations. Kinetic activation relaxation technique (k-ART) simulations for nickel showed that small vacancy clusters, such as di-vacancies and tri-vacancies, created by collision cascades are highly mobile, even at room temperature. The slower migration of defects in the alloy along with more localized energy dissipation of the displacement cascade may lead to enhanced radiation tolerance. PMID:26829570

A Feasibility Study to Determine Whether Clinical Contrast Enhanced Magnetic Resonance Imaging can Detect Increased Bladder Permeability in Patients with Interstitial Cystitis.

PubMed

Towner, Rheal A; Wisniewski, Amy B; Wu, Dee H; Van Gordon, Samuel B; Smith, Nataliya; North, Justin C; McElhaney, Rayburt; Aston, Christopher E; Shobeiri, S Abbas; Kropp, Bradley P; Greenwood-Van Meerveld, Beverley; Hurst, Robert E

2016-03-01

Interstitial cystitis/bladder pain syndrome is a bladder pain disorder associated with voiding symptomatology and other systemic chronic pain disorders. Currently diagnosing interstitial cystitis/bladder pain syndrome is complicated as patients present with a wide range of symptoms, physical examination findings and clinical test responses. One hypothesis is that interstitial cystitis symptoms arise from increased bladder permeability to urine solutes. This study establishes the feasibility of using contrast enhanced magnetic resonance imaging to quantify bladder permeability in patients with interstitial cystitis. Permeability alterations in bladder urothelium were assessed by intravesical administration of the magnetic resonance imaging contrast agent Gd-DTPA (Gd-diethylenetriaminepentaacetic acid) in a small cohort of patients. Magnetic resonance imaging signal intensity in patient and control bladders was compared regionally and for entire bladders. Quantitative assessment of magnetic resonance imaging signal intensity indicated a significant increase in signal intensity in anterior bladder regions compared to posterior regions in patients with interstitial cystitis (p <0.01) and significant increases in signal intensity in anterior bladder regions (p <0.001). Kurtosis (shape of probability distribution) and skewness (measure of probability distribution asymmetry) were associated with contrast enhancement in total bladders in patients with interstitial cystitis vs controls (p <0.05). Regarding symptomatology interstitial cystitis cases differed significantly from controls on the SF-36®, PUF (Pelvic Pain and Urgency/Frequency) and ICPI (Interstitial Cystitis Problem Index) questionnaires with no overlap in the score range in each group. ICSI (Interstitial Cystitis Symptom Index) differed significantly but with a slight overlap in the range of scores. Data suggest that contrast enhanced magnetic resonance imaging provides an objective, quantifiable measurement of bladder permeability that could be used to stratify bladder pain patients and monitor therapy. Copyright © 2016 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

Electrical resistivity of V-Cr-Ti alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zinkle, S.J.; Gubbi, A.N.; Eatherly, W.S.

1997-04-01

Room temperature electrical resistivity measurements have been performed on vanadium alloys containing 3-6%Cr and 3-6%Ti in order to evaluate the microstructural stability of these alloys. A nonlinear dependence on Cr and Ti concentration was observed, which suggests that either short range ordering or solute precipitation (perhaps in concert with interstitial solute clustering) has occurred in V-6Cr-6Ti.

Comparative study of displacement cascades simulated with 'magnetic' potentials and Mendelev-type potential in α-Fe

NASA Astrophysics Data System (ADS)

Gao, Chan; Tian, Dongfeng; Li, Maosheng; Qian, Dazhi

2017-04-01

Different interatomic potentials produce displacement cascades with different features, and hence they significantly influence the results obtained from the displacement cascade simulations. The displacement cascade simulations in α-Fe have been carried out by molecular dynamics with three 'magnetic' potentials (MP) and Mendelev-type potential in this paper. Prior to the cascade simulations, the 'magnetic' potentials are hardened to suit for cascade simulations. We find that the peak time, maximum of defects, cascade volume and cascade density with 'magnetic' potentials are smaller than those with Mendelev-type potential. There is no significant difference within statistical uncertainty in the defect production efficiency with Mendelev-type potential and the second 'magnetic' potential at the same cascade energy, but remarkably smaller than those with the first and third 'magnetic' potential. Self interstitial atom (SIA) clustered fractions with 'magnetic' potentials are smaller than that with Mendelev-type potential, especially at the higher energy, due to the larger interstitial formation energies which result from the 'magnetic' potentials. The defect clustered fractions, which are input data for radiation damage accumulation models, may influence the prediction of microstructural evolution under radiation.

Optimal doping control of magnetic semiconductors via subsurfactant epitaxy.

PubMed

Zeng, Changgan; Zhang, Zhenyu; van Benthem, Klaus; Chisholm, Matthew F; Weitering, Hanno H

2008-02-15

"Subsurfactant epitaxy" is established as a conceptually new approach for introducing manganese as a magnetic dopant into germanium. A kinetic pathway is devised in which the subsurface interstitial sites on Ge(100) are first selectively populated with Mn, while lateral diffusion and clustering on or underneath the surface are effectively suppressed. Subsequent Ge deposition as a capping layer produces a novel surfactantlike phenomenon as the interstitial Mn atoms float towards newly defined subsurface sites at the growth front. Furthermore, the Mn atoms that failed to float upwards are uniformly distributed within the Ge capping layer. The resulting doping levels of order 0.25 at. % would normally be considered too low for ferromagnetic ordering, but the Curie temperature exceeds room temperature by a comfortable margin. Subsurfactant epitaxy thus enables superior dopant control in magnetic semiconductors.

Tracing the `ninth sulfur' of the nitrogenase cofactor via a semi-synthetic approach

NASA Astrophysics Data System (ADS)

Tanifuji, Kazuki; Lee, Chi Chung; Sickerman, Nathaniel S.; Tatsumi, Kazuyuki; Ohki, Yasuhiro; Hu, Yilin; Ribbe, Markus W.

2018-05-01

The M-cluster is the [(homocitrate)MoFe7S9C] active site of nitrogenase that is derived from an 8Fe core assembled viacoupling and rearrangement of two [Fe4S4] clusters concomitant with the insertion of an interstitial carbon and a `ninth sulfur'. Combining synthetic [Fe4S4] clusters with an assembly protein template, here we show that sulfite can give rise to the ninth sulfur that is incorporated in the catalytically important belt region of the cofactor after the radical S-adenosyl-l-methionine-dependent carbide insertion and the concurrent 8Fe-core rearrangement have already taken place. Based on the differential reactivity of the formed cluster species, we also propose a new [Fe8S8C] cluster intermediate, the L*-cluster, which is similar to the [Fe8S9C] L-cluster, but lacks the ninth sulfur from sulfite. This work provides a semi-synthetic tool for protein reconstitution that could be widely applicable for the functional analysis of other FeS systems.

Tracing the 'ninth sulfur' of the nitrogenase cofactor via a semi-synthetic approach.

PubMed

Tanifuji, Kazuki; Lee, Chi Chung; Sickerman, Nathaniel S; Tatsumi, Kazuyuki; Ohki, Yasuhiro; Hu, Yilin; Ribbe, Markus W

2018-05-01

The M-cluster is the [(homocitrate)MoFe 7 S 9 C] active site of nitrogenase that is derived from an 8Fe core assembled viacoupling and rearrangement of two [Fe 4 S 4 ] clusters concomitant with the insertion of an interstitial carbon and a 'ninth sulfur'. Combining synthetic [Fe 4 S 4 ] clusters with an assembly protein template, here we show that sulfite can give rise to the ninth sulfur that is incorporated in the catalytically important belt region of the cofactor after the radical S-adenosyl-L-methionine-dependent carbide insertion and the concurrent 8Fe-core rearrangement have already taken place. Based on the differential reactivity of the formed cluster species, we also propose a new [Fe 8 S 8 C] cluster intermediate, the L*-cluster, which is similar to the [Fe 8 S 9 C] L-cluster, but lacks the ninth sulfur from sulfite. This work provides a semi-synthetic tool for protein reconstitution that could be widely applicable for the functional analysis of other FeS systems.

Non-malignant chest x ray changes in patients with mesothelioma in a large cohort of asbestos insulation workers.

PubMed Central

Lilis, R; Ribak, J; Suzuki, Y; Penner, L; Bernstein, N; Selikoff, I J

1987-01-01

To assess the prevalence of non-malignant chest x ray abnormalities in cases of mesothelioma 184 cases of mesothelioma (72 pleural and 112 peritoneal) which had occurred in a cohort of asbestos insulation workers followed up since 1967 were studied. Chest x ray films of satisfactory quality, on which the presence or absence of non-malignant radiological changes indicating interstitial pulmonary fibrosis or pleural fibrosis or both, could be assessed with a high degree of certainty were available. In some cases (20% for pleural mesothelioma, 11.6% for peritoneal mesothelioma) non-malignant radiological changes were not radiologically detectable. Parenchymal interstitial fibrosis (small irregular opacities) only was found in a proportion of cases (25.4% of pleural mesotheliomas, 12.5% of peritoneal mesotheliomas). Pleural fibrosis only was detected in 17% of cases of pleural mesothelioma and 27% of cases of peritoneal mesothelioma. Most patients had both parenchymal and pleural fibrosis. Although these results tend to indicate that in peritoneal mesothelioma the proportion of pleural fibrosis is significantly higher, these findings might have been due to the fact that in most cases of pleural mesothelioma non-malignant changes were interpreted in one hemithorax only. In 46 cases (21 pleural, 25 peritoneal) in which sufficient lung tissue was available histopathology of lung parenchyma indicated the presence of interstitial fibrosis; in 20 (43.5%) of these the chest x ray film had been read as negative. Thus the absence of radiologically detectable small opacities on the chest x ray film does not exclude the existence of interstitial pulmonary fibrosis in cases of mesothelioma among insulation workers. With lower levels of exposure (such as in family contacts of asbestos workers) it is conceivable that mesothelioma might occur in the absence of interstitial pulmonary fibrosis. PMID:3606969

Polyhydrido Copper Clusters: Synthetic Advances, Structural Diversity, and Nanocluster-to-Nanoparticle Conversion.

PubMed

Dhayal, Rajendra S; van Zyl, Werner E; Liu, C W

2016-01-19

Metal hydride clusters have historically been studied to unravel their aesthetically pleasing molecular structures and interesting properties, especially toward hydrogen related applications. Central to this work is the hydride ligand, H¯, the smallest closed-shell spherical anion known. Two new developments in polyhydrido nanocluster chemistry include the determination of heretofore unknown hydride coordination modes and novel structural constructs, and conversion from the molecular entities to rhombus-shaped copper nanoparticles (CuNPs). These advances, together with hydrogen evolution and catalysis, have provided both experimentalists and theorists with a rich scientific directive to further explore. The isolation of hexameric [{(Ph3P)CuH}6] (Stryker reagent) could be regarded as the springboard for the recent emergence of polyhydrido copper cluster chemistry due to its utilization in a variety of organic chemical transformations. The stability of clusters of various nuclearity was improved through phosphine, pyridine, and carbene type ligands. Our focus lies with the isolation of novel copper (poly)hydride clusters using mostly the phosphor-1,1-dithiolato type ligands. We found such chalcogen-stabilized clusters to be exceptionally air and moisture stable over a wide range of nuclearities (Cu7 to Cu32). In this Account, we (i) report on state-of-the-art copper hydride cluster chemistry, especially with regards to the diverse and novel structural types generally, and newly discovered hydride coordination modes in particular, (ii) demonstrate the indispensable power of neutron diffraction for the unambiguous assignment and location of hydride ligand(s) within a cluster, and (iii) prove unique transformations that can occur not only between well characterized high nuclearity clusters, but also how such clusters can transform to uniquely shaped nanoparticles of several nanometers in diameter through copper hydride reduction. The increase in the number of low- to high-nuclearity hydride clusters allows for different means by which they can be classified. We chose a classification based on the coordination mode of hydride ligand within the cluster. This includes copper clusters associated with bridging (μ2-H) and capping (μ3-H) hydride modes, followed by an interstitial (μ4-H) hydride mode that was introduced for the first time into octa- and hepta-nuclear copper clusters stabilized by dichalcogen-type ligands. This breakthrough provided a means to explore higher nuclearity polyhydrido nanoclusters, which contain both capping (μ3-H) and interstitial (μ(4-6)-H) hydrides. The presence of bidentate ligands having mixed S/P dative sites led to air- and moisture-stable copper hydride nanoclusters. The formation of rhombus-shaped nanoparticles (CuNPs) from copper polyhydrides in the presence of excess borohydrides suggests the presence of metal hydrides as intermediates during the formation of nanoparticles.

Radiation damage and defect behavior in proton irradiated lithium-counterdoped n+p silicon solar cells

NASA Technical Reports Server (NTRS)

Stupica, John; Goradia, Chandra; Swartz, Clifford K.; Weinberg, Irving

1987-01-01

Two lithium-counterdoped n+p silicon solar cells with different lithium concentrations were irradiated by 10-MeV protons. Cell performance was measured as a function of fluence, and it was found that the cell with the highest concentration of lithium had the highest radiation resistance. Deep level transient spectroscopy which showed two deep level defects that were lithium related. Relating the defect energy levels obtained from this study with those from earlier work using 1-MeV electron irradiation shows no correlation of the defect energy levels. There is one marked similarity: the absence of the boron-interstitial-oxygen-interstitial defect. This consistency strengthens the belief that lithium interacts with oxygen to prevent the formation of the boron interstitial-oxygen interstitial defect. The results indicate that, in general, addition of lithium in small amounts to the p-base of a boron doped silicon solar cell such that the base remains p-type, tends to increase the radiation resistance of the cell.

A case of deletion 14(q22.1-->q22.3) associated with anophthalmia and pituitary abnormalities.

PubMed Central

Elliott, J; Maltby, E L; Reynolds, B

1993-01-01

An interstitial deletion of the region q22.1-->q22.3 of chromosome 14 is described in a child with bilateral anophthalmia, dysmorphic features including micrognathia, small tongue, and high arched palate, developmental and growth retardation, undescended testes with a micropenis, and hypothyroidism. Interstitial deletions of the long arm of chromosome 14 are extremely rare, but this case seems to confirm that the region q22 is specifically concerned with pituitary and eye development. Images PMID:7682620

Visualization of T Cell-Regulated Monocyte Clusters Mediating Keratinocyte Death in Acquired Cutaneous Immunity.

PubMed

Liu, Zheng; Yang, Fei; Zheng, Hao; Fan, Zhan; Qiao, Sha; Liu, Lei; Tao, Juan; Luo, Qingming; Zhang, Zhihong

2018-06-01

It remains unclear how monocytes are mobilized to amplify inflammatory reactions in T cell-mediated adaptive immunity. Here, we investigate dynamic cellular events in the cascade of inflammatory responses through intravital imaging of a multicolor-labeled murine contact hypersensitivity model. We found that monocytes formed clusters around hair follicles in the contact hypersensitivity model. In this process, effector T cells encountered dendritic cells under regions of monocyte clusters and secreted IFN-γ, which mobilizes CCR2-dependent monocyte interstitial migration and CXCR2-dependent monocyte cluster formation. We showed that hair follicles shaped the inflammatory microenvironment for communication among the monocytes, keratinocytes, and effector T cells. After disrupting the T cell-mobilized monocyte clusters through CXCR2 antagonization, monocyte activation and keratinocyte apoptosis were significantly inhibited. Our study provides a new perspective on effector T cell-regulated monocyte behavior, which amplifies the inflammatory reaction in acquired cutaneous immunity. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

Annealing in tellurium-nitrogen co-doped ZnO films: The roles of intrinsic zinc defects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, Kun, E-mail: ktang@nju.edu.cn; Gu, Ran; Gu, Shulin, E-mail: slgu@nju.edu.cn

2015-04-07

In this article, the authors have conducted an extensive investigation on the roles of intrinsic zinc defects by annealing of a batch of Te-N co-doped ZnO films. The formation and annihilation of Zn interstitial (Zn{sub i}) clusters have been found in samples with different annealing temperatures. Electrical and Raman measurements have shown that the Zn{sub i} clusters are a significant compensation source to holes, and the Te co-doping has a notable effect on suppressing the Zn{sub i} clusters. Meanwhile, shallow acceptors have been identified in photoluminescence spectra. The N{sub O}-Zn-Te complex, zinc vacancy (V{sub Zn})-N{sub O} complex, and V{sub Zn}more » clusters are thought to be the candidates as the shallow acceptors. The evolution of shallow acceptors upon annealing temperature have been also studied. The clustering of V{sub Zn} at high annealing temperature is proposed to be a possible candidate as a stable acceptor in ZnO.« less

Cutaneous Pseudallescheria boydii/Scedosporium apiospermum Complex (Molecular type: Scedosporium apiospermum [Clade 4]) Infection: A Case Report and Literature Review of Cases from Japan.

PubMed

Ishii, Satoko; Hiruma, Midori; Hayakawa, Yuji; Sugita, Takashi; Makimura, Koichi; Hiruma, Masataro; Yoshiike, Takashi

2015-01-01

We report a case of subcutaneous Pseudallescheria boydii/Scedosporium apiospermum complex infection occurring in a 77-year-old Japanese female farmer suffering from interstitial pneumonia. Seven months prior to the current presentation, she noticed nodes on her right forearm after pulling up weeds, and the nodes grew larger. Two soft dome-shaped, protruded nodes ( 15 mm and 30 mm in size ) had fused together on the extensor surface of the right forearm. Yellowish-white, rice-grain-sized pustules clustered on the surface. Histopathological examination of the skin specimen showed large and small abscesses surrounded by epithelioid granuloma; separate branching hyphae within the granulation tissue were stained with PAS. No grains were observed. Fungal culture yielded fast-growing, grayish-white, fluffy colonies which were identified as Scedosporium apiospermum (Clade 4) using sequence analysis of the β-tubulin gene. We also reviewed 28 previously reported Japanese cases of P. boydii or S. apiospermum infection presenting with skin manifestations.

Characterization of swift heavy ion irradiation damage in ceria

DOE PAGES

Yablinsky, Clarissa A.; Devanathan, Ram; Pakarinen, Janne; ...

2015-03-04

Swift heavy ion induced radiation damage is investigated for ceria (CeO 2), which serves as a UO 2 fuel surrogate. Microstructural changes resulting from an irradiation with 940 MeV gold ions of 42 keV/nm electronic energy loss are investigated by means of electron microscopy accompanied by electron energy loss spectroscopy showing that there exists a small density reduction in the ion track core. While chemical changes in the ion track are not precluded, evidence of them was not observed. Classical molecular dynamics simulations of thermal spikes in CeO 2 with an energy deposition of 12 and 36 keV/nm show damagemore » consisting of isolated point defects at 12 keV/nm, and defect clusters at 36 keV/nm, with no amorphization at either energy. Furthermore, inferences are drawn from modeling about density changes in the ion track and the formation of interstitial loops that shed light on features observed by electron microscopy of swift heavy ion irradiated ceria.« less

The defect chemistry of UO2 ± x from atomistic simulations

NASA Astrophysics Data System (ADS)

Cooper, M. W. D.; Murphy, S. T.; Andersson, D. A.

2018-06-01

Control of the defect chemistry in UO2 ± x is important for manipulating nuclear fuel properties and fuel performance. For example, the uranium vacancy concentration is critical for fission gas release and sintering, while all oxygen and uranium defects are known to strongly influence thermal conductivity. Here the point defect concentrations in thermal equilibrium are predicted using defect energies from density functional theory (DFT) and vibrational entropies calculated using empirical potentials. Electrons and holes have been treated in a similar fashion to other charged defects allowing for structural relaxation around the localized electronic defects. Predictions are made for the defect concentrations and non-stoichiometry of UO2 ± x as a function of oxygen partial pressure and temperature. If vibrational entropy is omitted, oxygen interstitials are predicted to be the dominant mechanism of excess oxygen accommodation over only a small temperature range (1265 K-1350 K), in contrast to experimental observation. Conversely, if vibrational entropy is included oxygen interstitials dominate from 1165 K to 1680 K (Busker potential) or from 1275 K to 1630 K (CRG potential). Below these temperature ranges, excess oxygen is predicted to be accommodated by uranium vacancies, while above them the system is hypo-stoichiometric with oxygen deficiency accommodated by oxygen vacancies. Our results are discussed in the context of oxygen clustering, formation of U4O9, and issues for fuel behavior. In particular, the variation of the uranium vacancy concentrations as a function of temperature and oxygen partial pressure will underpin future studies into fission gas diffusivity and broaden the understanding of UO2 ± x sintering.

Energy partitioning and impulse dispersion in the decorated, tapered, strongly nonlinear granular alignment: A system with many potential applications

NASA Astrophysics Data System (ADS)

Doney, Robert L.; Agui, Juan H.; Sen, Surajit

2009-09-01

Rapid absorption of impulses using light-weight, small, reusable systems is a challenging problem. An axially aligned set of progressively shrinking elastic spheres, a "tapered chain," has been shown to be a versatile and scalable shock absorber in earlier simulational, theoretical, and experimental works by several authors. We have recently shown (see R. L. Doney and S. Sen, Phys. Rev. Lett. 97, 155502 (2006)) that the shock absorption ability of a tapered chain can be dramatically enhanced by placing small interstitial grains between the regular grains in the tapered chain systems. Here we focus on a detailed study of the problem introduced in the above mentioned letter, present extensive dynamical simulations using parameters for a titanium-aluminum-vanadium alloy Ti6Al4V, derive attendant hard-sphere analyses based formulae to describe energy dispersion, and finally discuss some preliminary experimental results using systems with chrome spheres and small Nitinol interstitial grains to present the underlying nonlinear dynamics of this so-called decorated tapered granular alignment. We are specifically interested in small systems, comprised of several grains. This is because in real applications, mass and volume occupied must inevitably be minimized. Our conclusion is that the decorated tapered chain offers enhanced energy dispersion by locking in much of the input energy in the grains of the tapered chain rather than in the small interstitial grains. Thus, the present study offers insights into how the shock absorption capabilities of these systems can be pushed even further by improving energy absorption capabilities of the larger grains in the tapered chains. We envision that these scalable, decorated tapered chains may be used as shock absorbing components in body armor, armored vehicles, building applications and in perhaps even in applications in rehabilitation science.

Synthesis and isolation of [Fe@Ge(10)](3-): a pentagonal prismatic Zintl ion cage encapsulating an interstitial iron atom.

PubMed

Zhou, Binbin; Denning, Mark S; Kays, Deborah L; Goicoechea, Jose M

2009-03-04

Reaction of an ethylenediamine (en) solution of the Zintl phase precursor K(4)Ge(9) with FeAr(2) (Ar = 2,6-Mes(2)C(6)H(3)) in the presence of 2,2,2-crypt (4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane) yielded the endohedral Zintl ion [Fe@Ge(10)](3-) (1) which was crystallographically characterized as a [K(2,2,2-crypt)](+) salt in [K(2,2,2-crypt)](3)[Fe@Ge(10)]*2en. This unprecedented Zintl ion exhibits a pentagonal prismatic 10-atom germanium cage with an interstitial iron atom in the central cavity. Confirmation of the existence of the cluster anion in solution was corroborated by positive and negative ion mode electrospray mass spectrometry.

Xenon Defects in Uranium Dioxide From First Principles and Interatomic Potentials

NASA Astrophysics Data System (ADS)

Thompson, Alexander

In this thesis, we examine the defect energetics and migration energies of xenon atoms in uranium dioxide (UO2) from first principles and interatomic potentials. We also parameterize new, accurate interatomic potentials for xenon and uranium dioxide. To achieve accurate energetics and provide a foundation for subsequent calculations, we address difficulties in finding consistent energetics within Hubbard U corrected density functional theory (DFT+U). We propose a method of slowly ramping the U parameter in order to guide the calculation into low energy orbital occupations. We find that this method is successful for a variety of materials. We then examine the defect energetics of several noble gas atoms in UO2 for several different defect sites. We show that the energy to incorporate large noble gas atoms into interstitial sites is so large that it is energetically favorable for a Schottky defect cluster to be created to relieve the strain. We find that, thermodynamically, xenon will rarely ever be in the interstitial site of UO2. To study larger defects associated with the migration of xenon in UO 2, we turn to interatomic potentials. We benchmark several previously published potentials against DFT+U defect energetics and migration barriers. Using a combination of molecular dynamics and nudged elastic band calculations, we find a new, low energy migration pathway for xenon in UO2. We create a new potential for xenon that yields accurate defect energetics. We fit this new potential with a method we call Iterative Potential Refinement that parameterizes potentials to first principles data via a genetic algorithm. The potential finds accurate energetics for defects with relatively low amounts of strain (xenon in defect clusters). It is important to find accurate energetics for these sorts of low-strain defects because they essentially represent small xenon bubbles. Finally, we parameterize a new UO2 potential that simultaneously yields accurate vibrational properties and defect energetics, important properties for UO2 because of the high temperature and defective reactor environment.. Previously published potentials could only yield accurate defect energetics or accurate phonons, but never both.

Towards understanding the mechanism of rhenium and osmium precipitation in tungsten and its implication for tungsten-based alloys

NASA Astrophysics Data System (ADS)

Li, Yu-Hao; Zhou, Hong-Bo; Deng, Huiqiu; Lu, Gang; Lu, Guang-Hong

2018-07-01

Using a first-principles method in combination with thermodynamic models, we investigate the interaction between rhenium/osmium (Re/Os) and defects to explore the mechanism of radiation-induced Re/Os precipitation in tungsten (W). We demonstrate that radiation-induced defects play a key role in the solute precipitation in W, especially for self-interstitial atoms (SIAs). The presence of SIAs can significantly reduce the total nucleation free energy change of Re/Os, and thus facilitate the nucleation of Re/Os in W. Further, SIA is shown to be easily trapped by Re/Os once overcoming a low energy barrier, forming a W-Re/Os mixed dumbbell. Such W-Re/Os dumbbell forms a high stable Re/Os-Re/Os dumbbell structure with the substitutional Re/Os atoms, which can serve as a trapping centre for subsequent interstitial-Re/Os, leading to the growth of Re/Os-rich clusters. Consequently, an interstitial-mediated migration and aggregation mechanism for Re/Os precipitation in W has been proposed. Our results reveale that the alloying elements-defects interaction has significantly effect on their behaviors under irradiation, which should be considered in the design of W-based alloys for future fusion devices.

Identifying self-interstitials of bcc and fcc crystals in molecular dynamics

NASA Astrophysics Data System (ADS)

Bukkuru, S.; Bhardwaj, U.; Warrier, M.; Rao, A. D. P.; Valsakumar, M. C.

2017-02-01

Identification of self-interstitials in molecular dynamics (MD) simulations is of critical importance. There exist several criteria for identifying the self-interstitial. Most of the existing methods use an assumed cut-off value for the displacement of an atom from its lattice position to identify the self-interstitial. The results obtained are affected by the chosen cut-off value. Moreover, these chosen cut-off values are independent of temperature. We have developed a novel unsupervised learning algorithm called Max-Space Clustering (MSC) to identify an appropriate cut-off value and its dependence on temperature. This method is compared with some widely used methods such as effective sphere (ES) method and nearest neighbor sphere (NNS) method. The cut-off radius obtained using our method shows a linear variation with temperature. The value of cut-off radius and its temperature dependence is derived for five bcc (Cr, Fe, Mo, Nb, W) and six fcc (Ag, Au, Cu, Ni, Pd, Pt) crystals. It is seen that the ratio of the cut-off values "r" to the lattice constant "a" lies between 0.23 and 0.3 at 300 K and this ratio is on an average smaller for the fcc crystals. Collision cascade simulations are carried out for Primary knock-on Atom (PKA) energies of 5 keV in Fe (at 300 K and 1000 K) and W (at 300 K and 2500 K) and the results are compared using the various methods.

Structure, stability and magnetism of cobalt doped (ZnO)n clusters.

PubMed

Yang, Jack; Zhang, Y B; Li, Sean

2011-03-01

Clusters of magnetic impurities are believed to play an important role in retaining ferromagnetism in diluted magnetic semiconductors (DMS), the origin of which has been a long debated issue. Controlling the dopant homogeneity in magnetic semiconductors is therefore a critical issue for the fabrication of high performance DMS. The current paper presents a first principle study on the stability and magnetic properties of Co doped (ZnO)n (n = 12 and 15) clusters using density functional theory. The results show that cobalt ions in these clusters tend to increase their stabilities by maximizing their co-ordination numbers to oxygen. This will likely to be the case for (ZnO)n clusters with n other than 12 and 15 in order for Co to reside in a stable local crystal field. Expansive (shrinkage) stress is introduced when cobalt resides in exohedral substitutional (endohedral interstitial) sites; such strain can be offset by the cluster deformation. Bidoped cluster is found to be unstable due to the increase of system strain energy. All the doped clusters were found to preserve 3 microg of magnetic moments from Co in the overall clusters, but with part of the local moments on cobalt re-distributed onto neighboring oxygen atoms. Current findings may provide a better understanding on the structural chemistry of magnetic dopants in nanocrystallined DMS materials.

Investigation of Synthetic Mg(1.3)V(1.7)O4 Spinel with MgO Inclusions: Case Study of a Spinel with an Apparently occupied Interstitial Site

NASA Technical Reports Server (NTRS)

Uchida, Hinako; Righter, Kevin; Lavina, Barbara; Nowell, Matthew M.; Wright, Stuart I.; Downs, Robert T.; Yang, Hexiong

2007-01-01

A magnesium vanadate spinel crystal, ideally MgV2O4, synthesized at 1 bar, 1200 C and equilibrated under FMQ + 1.3 log f(sub o2) condition, was investigated using single-crystal X-ray diffraction, electron microprobe, and electron backscatter (EBSD). The initial X-ray structure refinements gave tetrahedral and octahedral site occupancies, along with the presence of 0.053 apfu Mg at an interstitial octahedral site . Back-scattered electron (BSE) images and electron microprobe analyses revealed the existence of an Mg-rich phase in the spinel matrix, which was too small (less than or equal to 3microns) for an accurate chemical determination. The EBSD analysis combined with X-ray energy dispersive spectroscop[y (XEDS) suggested that the Mg-rich inclusions are periclase oriented coherently with the spinel matrix. The final structure refinements were optimized by subtracting the X-ray intensity contributions (approx. 9%) of periclase reflections, which eliminated the interstitial Mg. This study provides insight into possible origins of refined interstitial cations reported in the the literature for spinel, and points to the difficulty of using only X-ray diffraction data to distinguish a spinel with interstitial cations from one with coherently oriented MgO inclusions.

An empirical potential for simulating vacancy clusters in tungsten.

PubMed

Mason, D R; Nguyen-Manh, D; Becquart, C S

2017-12-20

We present an empirical interatomic potential for tungsten, particularly well suited for simulations of vacancy-type defects. We compare energies and structures of vacancy clusters generated with the empirical potential with an extensive new database of values computed using density functional theory, and show that the new potential predicts low-energy defect structures and formation energies with high accuracy. A significant difference to other popular embedded-atom empirical potentials for tungsten is the correct prediction of surface energies. Interstitial properties and short-range pairwise behaviour remain similar to the Ackford-Thetford potential on which it is based, making this potential well-suited to simulations of microstructural evolution following irradiation damage cascades. Using atomistic kinetic Monte Carlo simulations, we predict vacancy cluster dissociation in the range 1100-1300 K, the temperature range generally associated with stage IV recovery.

Direct Observation of Defect Range and Evolution in Ion-Irradiated Single Crystalline Ni and Ni Binary Alloys

DOE PAGES

Lu, Chenyang; Jin, Ke; Béland, Laurent K.; ...

2016-02-01

We report that energetic ions have been widely used to evaluate the irradiation tolerance of structural materials for nuclear power applications and to modify material properties. It is important to understand the defect production, annihilation and migration mechanisms during and after collision cascades. In this study, single crystalline pure nickel metal and single-phase concentrated solid solution alloys of 50%Ni50%Co (NiCo) and 50%Ni50%Fe (NiFe) without apparent preexisting defect sinks were employed to study defect dynamics under ion irradiation. Both cross-sectional transmission electron microscopy characterization (TEM) and Rutherford backscattering spectrometry channeling (RBS-C) spectra show that the range of radiation-induced defect clusters farmore » exceed the theoretically predicted depth in all materials after high-dose irradiation. Defects in nickel migrate faster than in NiCo and NiFe. Both vacancy-type stacking fault tetrahedra (SFT) and interstitial loops coexist in the same region, which is consistent with molecular dynamics simulations. Kinetic activation relaxation technique (k-ART) simulations for nickel showed that small vacancy clusters, such as di-vacancies and tri-vacancies, created by collision cascades are highly mobile, even at room temperature. The slower migration of defects in the alloy along with more localized energy dissipation of the displacement cascade may lead to enhanced radiation tolerance.« less

Non-invasive imaging of barriers to drug delivery in tumors.

PubMed

Hassid, Yaron; Eyal, Erez; Margalit, Raanan; Furman-Haran, Edna; Degani, Hadassa

2008-08-01

Solid tumors often develop high interstitial fluid pressure (IFP) as a result of increased water leakage and impaired lymphatic drainage, as well as changes in the extracellular matrix composition and elasticity. This high fluid pressure forms a barrier to drug delivery and hence, resistance to therapy. We have developed techniques based on contrast enhanced magnetic resonance imaging for mapping in tumors the vascular and transport parameters determining the delivery efficiency of blood borne substances. Sequential images are recorded during continuous infusion of a Gd-based contrast agent and analyzed according to a new physiological model, yielding maps of microvascular transfer constants, as well as outward convective interstitial transfer constants and steady state interstitial contrast agent concentrations both reflecting IFP distribution. We further demonstrated in non small cell human lung cancer xenografts the capability of our techniques to monitor in vivo collagenase induced increase in contrast agent delivery as a result of decreased IFP. These techniques can be applied to test drugs that affect angiogenesis and modulate interstitial fluid pressure and has the potential to be extended to cancer patients for assessing resistance to drug delivery.

Non-Invasive Imaging of Barriers to Drug Delivery in Tumors

PubMed Central

Hassid, Yaron; Eyal, Erez; Margalit, Raanan; Furman-Haran, Edna; Degani, Hadassa

2011-01-01

Solid tumors often develop high interstitial fluid pressure (IFP) as a result of increased water leakage and impaired lymphatic drainage, as well as changes in the extracellular matrix composition and elasticity. This high fluid pressure forms a barrier to drug delivery and hence, resistance to therapy. We have developed techniques based on contrast enhanced magnetic resonance imaging for mapping in tumors the vascular and transport parameters determining the delivery efficiency of blood borne substances. Sequential images are recorded during continuous infusion of a Gd-based contrast agent and analyzed according to a new physiological model, yielding maps of microvascular transfer constants, as well as outward convective interstitial transfer constants and steady state interstitial contrast agent concentrations both reflecting IFP distribution. We further demonstrated in non small cell human lung cancer xenografts the capability of our techniques to monitor in vivo collagenase induced increase in contrast agent delivery as a result of decreased IFP. These techniques can be applied to test drugs that affect angiogenesis and modulate interstitial fluid pressure and has the potential to be extended to cancer patients for assessing resistance to drug delivery. PMID:18638494

Characterization of the Tumor Secretome from Tumor Interstitial Fluid (TIF).

PubMed

Gromov, Pavel; Gromova, Irina

2016-01-01

Tumor interstitial fluid (TIF) surrounds and perfuses bodily tumorigenic tissues and cells, and can accumulate by-products of tumors and stromal cells in a relatively local space. Interstitial fluid offers several important advantages for biomarker and therapeutic target discovery, especially for cancer. Here, we describe the most currently accepted method for recovering TIF from tumor and nonmalignant tissues that was initially performed using breast cancer tissue. TIF recovery is achieved by passive extraction of fluid from small, surgically dissected tissue specimens in phosphate-buffered saline. We also present protocols for hematoxylin and eosin (H&E) staining of snap-frozen and formalin-fixed, paraffin-embedded (FFPE) tumor sections and for proteomic profiling of TIF and matched tumor samples by high-resolution two-dimensional gel electrophoresis (2D-PAGE) to enable comparative analysis of tumor secretome and paired tumor tissue.

Leg blood flow is impaired during small muscle mass exercise in patients with COPD.

PubMed

Iepsen, U W; Munch, G W; Rugbjerg, M; Ryrsø, C K; Secher, N H; Hellsten, Y; Lange, P; Pedersen, B K; Thaning, P; Mortensen, S P

2017-09-01

Skeletal muscle blood flow is regulated to match the oxygen demand and dysregulation could contribute to exercise intolerance in patients with chronic obstructive pulmonary disease (COPD). We measured leg hemodynamics and metabolites from vasoactive compounds in muscle interstitial fluid and plasma at rest, during one-legged knee-extensor exercise, and during arterial infusions of sodium nitroprusside (SNP) and acetylcholine (ACh), respectively. Ten patients with moderate to severe COPD and eight age- and sex-matched healthy controls were studied. During knee-extensor exercise (10 W), leg blood flow was lower in the patients compared with the controls (1.82 ± 0.11 vs. 2.36 ± 0.14 l/min, respectively; P < 0.05), which compromised leg oxygen delivery (372 ± 26 vs. 453 ± 32 ml O 2 /min, respectively; P < 0.05). At rest, plasma endothelin-1 (vasoconstrictor) was higher in the patients with COPD ( P < 0.05) and also tended to be higher during exercise ( P = 0.07), whereas the formation of interstitial prostacyclin (vasodilator) was only increased in the controls. There was no difference between groups in the nitrite/nitrate levels (vasodilator) in plasma or interstitial fluid during exercise. Moreover, patients and controls showed similar vasodilatory capacity in response to both endothelium-independent (SNP) and endothelium-dependent (ACh) stimulation. The results suggest that leg muscle blood flow is impaired during small muscle mass exercise in patients with COPD possibly due to impaired formation of prostacyclin and increased levels of endothelin-1. NEW & NOTEWORTHY This study demonstrates that chronic obstructive pulmonary disease (COPD) is associated with a reduced blood flow to skeletal muscle during small muscle mass exercise. In contrast to healthy individuals, interstitial prostacyclin levels did not increase during exercise and plasma endothelin-1 levels were higher in the patients with COPD. Copyright © 2017 the American Physiological Society.

High-Performance and Traditional Multicrystalline Silicon: Comparing Gettering Responses and Lifetime-Limiting Defects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Castellanos, Sergio; Ekstrom, Kai E.; Autruffe, Antoine

2016-05-01

In recent years, high-performance multicrystalline silicon (HPMC-Si) has emerged as an attractive alternative to traditional ingot-based multicrystalline silicon (mc-Si), with a similar cost structure but improved cell performance. Herein, we evaluate the gettering response of traditional mc-Si and HPMC-Si. Microanalytical techniques demonstrate that HPMC-Si and mc-Si share similar lifetime-limiting defect types but have different relative concentrations and distributions. HPMC-Si shows a substantial lifetime improvement after P-gettering compared with mc-Si, chiefly because of lower area fraction of dislocation-rich clusters. In both materials, the dislocation clusters and grain boundaries were associated with relatively higher interstitial iron point-defect concentrations after diffusion, which ismore » suggestive of dissolving metal-impurity precipitates. The relatively fewer dislocation clusters in HPMC-Si are shown to exhibit similar characteristics to those found in mc-Si. Given similar governing principles, a proxy to determine relative recombination activity of dislocation clusters developed for mc-Si is successfully transferred to HPMC-Si.« less

Effect of solute atom concentration on vacancy cluster formation in neutron-irradiated Ni alloys

NASA Astrophysics Data System (ADS)

Sato, Koichi; Itoh, Daiki; Yoshiie, Toshimasa; Xu, Qiu; Taniguchi, Akihiro; Toyama, Takeshi

2011-10-01

The dependence of microstructural evolution on solute atom concentration in Ni alloys was investigated by positron annihilation lifetime measurements. The positron annihilation lifetimes in pure Ni, Ni-0.05 at.%Si, Ni-0.05 at.%Sn, Ni-Cu, and Ni-Ge alloys were about 400 ps even at a low irradiation dose of 3 × 10 -4 dpa, indicating the presence of microvoids in these alloys. The size of vacancy clusters in Ni-Si and Ni-Sn alloys decreased with an increase in the solute atom concentration at irradiation doses less than 0.1 dpa; vacancy clusters started to grow at an irradiation dose of about 0.1 dpa. In Ni-2 at.%Si, irradiation-induced segregation was detected by positron annihilation coincidence Doppler broadening measurements. This segregation suppressed one-dimensional (1-D) motion of the interstitial clusters and promoted mutual annihilation of point defects. The frequency and mean free path of the 1-D motion depended on the solute atom concentration and the amount of segregation.

The role of nickel in radiation damage of ferritic alloys

DOE PAGES

Osetsky, Y.; Anento, Napoleon; Serra, Anna; ...

2014-11-26

According to modern theory, damage evolution under neutron irradiation depends on the fraction of self-interstitial atoms (SIAs) produced in the form of one-dimensional glissile clusters. These clusters, having a low interaction cross-section with other defects, are absorbed mainly by grain boundaries and dislocations, creating the so-called production bias. It is known empirically that the addition of certain alloying elements influences many radiation effects, including swelling; however, the mechanisms are unknown in many cases. In this study, we report the results of an extensive multi-technique atomistic level modeling study of SIA clusters mobility in body-centered cubic Fe–Ni alloys. We have foundmore » that Ni interacts strongly with the periphery of clusters, affecting their mobility. The total effect is defined by the number of Ni atoms interacting with the cluster at the same time and can be significant, even in low-Ni alloys. Thus a 1 nm (37SIAs) cluster is practically immobile at T < 500 K in the Fe–0.8 at.% Ni alloy. Increasing cluster size and Ni content enhances cluster immobilization. Finally, this effect should have quite broad consequences in void swelling, matrix damage accumulation and radiation induced hardening and the results obtained help to better understand and predict the effects of radiation in Fe–Ni ferritic alloys.« less

Assessment and management of refractory breathlessness in interstitial lung disease.

PubMed

Speakman, Lucy; Walthall, Helen

2017-09-02

Interstitial lung disease (ILD) refers to a cluster of fibroinflammatory conditions. There are limited treatment options and most patients have severe dyspnoea. The prognosis is poor. This study aims to evaluate current literature on the assessment and management of refractory breathlessness in ILD. Few tools are available to assess dyspnoea in advanced respiratory disease. Holistic assessment requires a combination of tools but there are few disease specific tools. The role of opioids is well established in the reduction of breathlessness, but there is insufficient evidence that benzodiazepines are beneficial. Non-pharmcolological breathlessness intervention services can give patients mastery of their disease, reduced distress due to breathlessness and were more cost effective. More research on holistic interventions for use in advanced disease needs to be done. Patient-reported outcome measures could elicit valuable evidence to describe the benefit of breathlessness management services in advanced respiratory disease.

Interstitial water studies on small core samples, Deep Sea Drilling Project: Leg 10

USGS Publications Warehouse

Manheim, Frank T.; Sayles, Fred L.; Waterman, Lee S.

1973-01-01

Leg 10 interstitial water analyses provide new indications of the distribution of rock salt beneath the floor of the Gulf of Mexico, both confirming areas previously indicated to be underlain by salt bodies and extending evidence of salt distribution to seismically featureless areas in the Sigsbee Knolls trend and Isthmian Embayment. The criterion for presence of salt at depth is a consistent increase in interstitial salinity and chlorinity with depth. Site 86, on the northern margin of the Yucatan Platform, provided no evidence of salt at depth. Thus, our data tend to rule out the suggestion of Antoine and Bryant (1969) that the Sigsbee Knolls salt was squeezed out from beneath the Yucatan Scarp. Cores from Sites 90 and 91, in the central Sigsbee Deep, were not obtained from a great enough depth to yield definite evidence for the presence of buried salt.

Radiation tolerance of nanocrystalline ceramics: insights from Yttria Stabilized Zirconia.

PubMed

Dey, Sanchita; Drazin, John W; Wang, Yongqiang; Valdez, James A; Holesinger, Terry G; Uberuaga, Blas P; Castro, Ricardo H R

2015-01-13

Materials for applications in hostile environments, such as nuclear reactors or radioactive waste immobilization, require extremely high resistance to radiation damage, such as resistance to amorphization or volume swelling. Nanocrystalline materials have been reported to present exceptionally high radiation-tolerance to amorphization. In principle, grain boundaries that are prevalent in nanomaterials could act as sinks for point-defects, enhancing defect recombination. In this paper we present evidence for this mechanism in nanograined Yttria Stabilized Zirconia (YSZ), associated with the observation that the concentration of defects after irradiation using heavy ions (Kr(+), 400 keV) is inversely proportional to the grain size. HAADF images suggest the short migration distances in nanograined YSZ allow radiation induced interstitials to reach the grain boundaries on the irradiation time scale, leaving behind only vacancy clusters distributed within the grain. Because of the relatively low temperature of the irradiations and the fact that interstitials diffuse thermally more slowly than vacancies, this result indicates that the interstitials must reach the boundaries directly in the collision cascade, consistent with previous simulation results. Concomitant radiation-induced grain growth was observed which, as a consequence of the non-uniform implantation, caused cracking of the nano-samples induced by local stresses at the irradiated/non-irradiated interfaces.

Radiation Tolerance of Nanocrystalline Ceramics: Insights from Yttria Stabilized Zirconia

PubMed Central

Dey, Sanchita; Drazin, John W.; Wang, Yongqiang; Valdez, James A.; Holesinger, Terry G.; Uberuaga, Blas P.; Castro, Ricardo H. R.

2015-01-01

Materials for applications in hostile environments, such as nuclear reactors or radioactive waste immobilization, require extremely high resistance to radiation damage, such as resistance to amorphization or volume swelling. Nanocrystalline materials have been reported to present exceptionally high radiation-tolerance to amorphization. In principle, grain boundaries that are prevalent in nanomaterials could act as sinks for point-defects, enhancing defect recombination. In this paper we present evidence for this mechanism in nanograined Yttria Stabilized Zirconia (YSZ), associated with the observation that the concentration of defects after irradiation using heavy ions (Kr+, 400 keV) is inversely proportional to the grain size. HAADF images suggest the short migration distances in nanograined YSZ allow radiation induced interstitials to reach the grain boundaries on the irradiation time scale, leaving behind only vacancy clusters distributed within the grain. Because of the relatively low temperature of the irradiations and the fact that interstitials diffuse thermally more slowly than vacancies, this result indicates that the interstitials must reach the boundaries directly in the collision cascade, consistent with previous simulation results. Concomitant radiation-induced grain growth was observed which, as a consequence of the non-uniform implantation, caused cracking of the nano-samples induced by local stresses at the irradiated/non-irradiated interfaces. PMID:25582769

Radiation tolerance of nanocrystalline ceramics: Insights from yttria stabilized zirconia

DOE PAGES

Dey, Sanchita; Drazin, John W.; Wang, Yongqiang; ...

2015-01-13

Materials for applications in hostile environments, such as nuclear reactors or radioactive waste immobilization, require extremely high resistance to radiation damage, such as resistance to amorphization or volume swelling. Nanocrystalline materials have been reported to present exceptionally high radiation-tolerance to amorphization. In principle, grain boundaries that are prevalent in nanomaterials could act as sinks for point-defects, enhancing defect recombination. In this paper we present evidence for this mechanism in nanograined Yttria Stabilized Zirconia (YSZ), associated with the observation that the concentration of defects after irradiation using heavy ions (Kr⁺, 400 keV) is inversely proportional to the grain size. HAADF imagesmore » suggest the short migration distances in nanograined YSZ allow radiation induced interstitials to reach the grain boundaries on the irradiation time scale, leaving behind only vacancy clusters distributed within the grain. Because of the relatively low temperature of the irradiations and the fact that interstitials diffuse thermally more slowly than vacancies, this result indicates that the interstitials must reach the boundaries directly in the collision cascade, consistent with previous simulation results. Concomitant radiation-induced grain growth was observed which, as a consequence of the non-uniform implantation, caused cracking of the nano-samples induced by local stresses at the irradiated/non-irradiated interfaces.« less

Smoking-related interstitial fibrosis combined with pulmonary emphysema: computed tomography-pathologic correlative study using lobectomy specimens.

PubMed

Otani, Hideji; Tanaka, Tomonori; Murata, Kiyoshi; Fukuoka, Junya; Nitta, Norihisa; Nagatani, Yukihiro; Sonoda, Akinaga; Takahashi, Masashi

2016-01-01

To evaluate the incidence and pathologic correlation of thin-section computed tomography (TSCT) findings in smoking-related interstitial fibrosis (SRIF) with pulmonary emphysema. Our study included 172 consecutive patients who underwent TSCT and subsequent lobectomy. TSCT findings including clustered cysts with visible walls (CCVW) and ground-glass attenuation with/without reticulation (GGAR) were evaluated and compared in nonsmokers and smokers and among lung locations. TSCT findings, especially CCVW, were also compared with histological findings using lobectomy specimens. The incidence of CCVW and GGAR was significantly higher in smokers than in nonsmokers (34.1% and 40.7%, respectively, vs 2.0% and 12.2%). CCVW and GGAR were frequently found in the lower and peripheral zones. Histologically, CCVW corresponded more often with SRIF with emphysema than usual interstitial pneumonia (UIP, 63.3% vs 30%). CCVW of irregular size and shape were seen in 19 of 20 SRIF with emphysema and in seven of nine UIP-manifested areas with similar round cysts. A less-involved subpleural parenchyma was observed more frequently in SRIF with emphysema. SRIF with emphysema is a more frequent pathological finding than UIP in patients with CCVW on TSCT. The irregular size and shape of CCVW and a less-involved subpleural parenchyma may be a clue suggesting the presence of SRIF with emphysema.

Microstructure, mixing rules and interfacial behavior in high k barium titanate epoxy composite

NASA Astrophysics Data System (ADS)

Shi, Yitong (Thomas)

2001-07-01

In this thesis, we have demonstrated the importance of two issues in BaTiO3/epoxy composites. They are (1) the miscibility of a particle blend in organic vehicle, i.e. the capability of particles with different particle sizes to mix at the particle level, and (2) the ceramic/polymer interface as a role in determining the effective dielectric constant. The epoxy matrix between the BaTiO3 particles is not homogeneous and has to be modeled as a two-layer structure. The inhomogeneity causes not only failure of the existing mixing rules but also the particle size dependence of the effective dielectric constant. Since the interfacial behavior is determined by the materials chemistry, the effective dielectric properties experimentally demonstrate strong dependence on the materials selection and processing. If BaTiO3 particles in liquid epoxy resin has a bimodal particle size distribution, the smaller particles do not experimentally fit into the interstitial spaces between the larger spheres in an organic vehicle. ESEM observations indicated that the large particles separated from the small ones. Depending on the paste formula, the particle separation led to either a layer-like or cluster-like microstructure. The mixing free energy of blending smaller particles with larger particles explains the observed phenomena and suggests general criteria for particle miscibility. Whenever the mixing free energy is negative and the mixing free energy curve is convex, the particle blend remains in a random particle distribution. Otherwise, the particles separate into a larger-particle rich "phase" and a smaller-particle rich "phase". A random particle distribution may be the largest degree of mixing we can achieve in an organic vehicle. If there is no specific interaction between the small particles and the large particles, there is no thermodynamic driving force for small particles to fill preferentially into the interstitial spaces between the large spheres. The Hamaker constant H significantly influences the miscibility of a particle blend. An increase in Hamaker constant H causes not only greater driving force for a particle blend to separate but also a more narrowed convex shape---the mixing window. At a specific composition, a particle blend separates in one vehicle but may remain in a random distribution in another vehicle if the later vehicle has significantly reduced the Hamaker constant H.

Sphere based fluid systems

NASA Technical Reports Server (NTRS)

Elleman, Daniel D. (Inventor); Wang, Taylor G. (Inventor)

1989-01-01

Systems are described for using multiple closely-packed spheres. In one system for passing fluid, a multiplicity of spheres lie within a container, with all of the spheres having the same outside diameter and with the spheres being closely nested in one another to create multiple interstitial passages of a known size and configuration and smooth walls. The container has an inlet and outlet for passing fluid through the interstitial passages formed between the nested spheres. The small interstitial passages can be used to filter out material, especially biological material such as cells in a fluid, where the cells can be easily destroyed if passed across sharp edges. The outer surface of the spheres can contain a material that absorbs a constitutent in the flowing fluid, such as a particular contamination gas, or can contain a catalyst to chemically react the fluid passing therethrough, the use of multiple small spheres assuring a large area of contact of these surfaces of the spheres with the fluid. In a system for storing and releasing a fluid such as hydrogen as a fuel, the spheres can include a hollow shell containing the fluid to be stored, and located within a compressable container that can be compressed to break the shells and release the stored fluid.

Co-located hAT transposable element and 5S rDNA in an interstitial telomeric sequence suggest the formation of Robertsonian fusion in armored catfish.

PubMed

Glugoski, Larissa; Giuliano-Caetano, Lucia; Moreira-Filho, Orlando; Vicari, Marcelo R; Nogaroto, Viviane

2018-04-15

Co-located 5S rDNA genes and interstitial telomeric sites (ITS) revealed the involvement of multiple 5S rDNA clusters in chromosome rearrangements of Loricariidae. Interstitial (TTAGGG)n vestiges, in addition to telomeric sites, can coincide with locations of chromosomal rearrangements, and they are considered to be hotspots for chromosome breaks. This study aimed the molecular characterization of 5S rDNA in two Rineloricaria latirostris populations and examination of roles of 5S rDNA in breakpoint sites and its in situ localization. Rineloricaria latirostris from Brazil's Das Pedras river (2n = 46 chromosomes) presented five pairs identified using a 5S rDNA probe, in addition to a pair bearing a co-located ITS/5S rDNA. Rineloricaria latirostris from the Piumhi river (2n = 48 chromosomes) revealed two pairs containing 5S rDNA, without ITS. A 702-bp amplified sequence, using 5S rDNA primers, revealed an insertion of the hAT transposable element (TE), referred to as a degenerate 5S rDNA. Double-FISH (fluorescence in situ hybridization) demonstrated co-localization of 5S rDNA/degenerate 5S rDNA, 5S rDNA/hAT and ITS/5S rDNA from the Das Pedras river population. Piumhi river isolates possessed only 5S rDNA sites. We suggest that the degenerate 5S rDNA was generated by unequal crossing over, which was driven by invasion of hAT, establishing a breakpoint region susceptible to chromosome breakage, non-homologous recombination and Robertsonian (Rb) fusion. Furthermore, the presence of clusters of 5S rDNA at fusion points in other armored catfish species suggests its re-use and that these regions represent hotspots for evolutionary rearrangements within Loricariidae genomes. Copyright © 2018 Elsevier B.V. All rights reserved.

Histological evolution of pleuroparenchymal fibroelastosis

PubMed Central

Hirota, Takako; Yoshida, Yuji; Kitasato, Yasuhiko; Yoshimi, Michihiro; Koga, Takaomi; Tsuruta, Nobuko; Minami, Masato; Harada, Taishi; Ishii, Hiroshi; Fujita, Masaki; Nabeshima, Kazuki; Nagata, Nobuhiko; Watanabe, Kentaro

2015-01-01

Aims To investigate the histological evolution in the development of pleuroparenchymal fibroelastosis (PPFE). Methods and results We examined four patients who had undergone surgical lung biopsy twice, or who had undergone surgical lung biopsy and had been autopsied, and in whom the histological diagnosis of the first biopsy was not PPFE, but the diagnosis of the second biopsy or of the autopsy was PPFE. The histological patterns of the first biopsy were cellular and fibrotic interstitial pneumonia, cellular interstitial pneumonia (CIP) with organizing pneumonia, CIP with granulomas and acute lung injury in cases 1, 2, 3, and 4, respectively. Septal elastosis was already present in the non-specific interstitial pneumonia-like histology of case 1, but a few additional years were necessary to reach consolidated subpleural fibroelastosis. In case 3, subpleural fibroelastosis was already present in the first biopsy, but only to a small extent. Twelve years later, it was replaced by a long band of fibroelastosis. The septal inflammation and fibrosis and airspace organization observed in the first biopsies were replaced by less cellular subpleural fibroelastosis within 3–12 years. Conclusions Interstitial inflammation or acute lung injury may be an initial step in the development of PPFE. PMID:25234959

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dhayal, Rajendra S.; Liao, Jian-Hong; Kahlal, Samia

An air- and moisture-stable nanoscale polyhydrido copper cluster [Cu 32(H) 20{S 2P(O i Pr) 2 } 12 ] (1 H) was synthesized and structurally characterized. The molecular structure of 1 H exhibits a hexacapped pseudo-rhombohedral core of 14 Cu atoms sandwiched between two nestlike triangular cupola fragments of (2x9) Cu atoms in an elongated triangular gyrobicupola polyhedron. The discrete Cu 32 cluster is stabilized by 12 dithiophosphate ligands and a record number of 20 hydride ligands, which were found by high-resolution neutron diffraction to exhibit tri-, tetra-, and pentacoordinated hydrides in capping and interstitial modes. We conclude that this resultmore » was further supported by a density functional theory investigation on the simplified model [Cu 32(H) 20(S 2PH 2) 12].« less

Distribution and components of interstitial inflammation and fibrosis in IgG4-related kidney disease: analysis of autopsy specimens.

PubMed

Hara, Satoshi; Kawano, Mitsuhiro; Mizushima, Ichiro; Harada, Kenichi; Takata, Takuma; Saeki, Takako; Ubara, Yoshifumi; Sato, Yasuharu; Nagata, Michio

2016-09-01

IgG4-related kidney disease (IgG4-RKD) occasionally progresses to chronic renal failure and is pathologically characterized by IgG4-positive lymphoplasmacyte-rich tubulointerstitial nephritis with storiform fibrosis (bird's-eye pattern fibrosis). Although radiology reveals a heterogeneous distribution of affected areas in this disease, their true distribution within the whole kidney is still unknown because of difficulty in estimating this from needle biopsy samples. Using 5 autopsy specimens, the present study histologically characterized the distribution and components of interstitial inflammation and fibrosis in IgG4-RKD. Interstitial lymphoplasmacytic infiltration or fibrosis was observed in a variety of anatomical locations such as intracapsular, subcapsular, cortical, perivascular, and perineural regions heterogeneously in a patchy distribution. They tended to be more markedly accumulated around medium- and small-sized vessels. Storiform fibrosis was limited to the cortex. Immunostaining revealed nonfibrillar collagens (collagen IV and VI) and fibronectin predominance in the cortical lesion, including storiform fibrosis. In contrast, fibril-forming collagens (collagen I and III), collagen VI, and fibronectin were the main components in the perivascular lesion. In addition, α-smooth muscle actin-positive myofibroblasts were prominently accumulated in the early lesion and decreased with progression, suggesting that myofibroblasts produce extracellular matrices forming a peculiar fibrosis. In conclusion, perivascular inflammation or fibrosis of medium- and small-sized vessels is a newly identified pathologic feature of IgG4-RKD. Because storiform fibrosis contains mainly nonfibrillar collagens, "interstitial fibrosclerosis" would be a suitable term to reflect this. The relation between the location and components of fibrosis determined in whole kidney samples provides new clues to the pathophysiology underlying IgG4-RKD. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Image guidance, treatment planning and evaluation of cancer interstitial focal therapy using liposomal radionuclides

NASA Astrophysics Data System (ADS)

Ware, Steve William

Focally ablative therapy of cancer has gained significant interest recently. Improvements in diagnostic techniques have created possibilities for treatment which were once clinically unfeasible. Imaging must be capable of allowing accurate diagnosis, staging and planning upon initiation of therapy. Recent improvements in MRI and molecular imaging techniques have made it possible to accurately localize lesions and in so doing, improve the accuracy of proposed focal treatments. Using multimodality imaging it is now possible to target, plan and evaluate interstitial focal treatment using liposome encapsulated beta emitting radionuclides in a variety of cancer types. Since most absorbed dose is deposited early and heterogeneously in beta-radionuclide therapy, investigation of the resultant molecular and cellular events during this time is important for evaluating treatment efficacy. Additionally, investigating a multifocal entity such as prostate cancer is helpful for determining whether MRI is capable of discriminating the proper lesion for therapy. Correlation of MRI findings with histopathology can further improve the accuracy of interstitial focal radionuclide therapy by providing non-invasive surrogates for tissue compartment sizes. In the application of such therapies, compartmental sizes are known to heavily influence the distribution of injected agents. This has clear dosimetric implications with the potential to significantly alter the efficacy of treatment. The hypothesis of this project was that multimodality imaging with magnetic resonance imaging (MRI), autoradiography (AR), and single photon emission computed tomography (SPECT) could be used to target, plan, and evaluate interstitial focal therapy with non-sealed source, liposome-encapsulated 186Re beta emitting radionuclides. The specific aims of this project were to 1) Identify suitable targets for interstitial focal therapy. This was done by retrospectively analyzing MRI data to characterize the tumor microenvironment through correlation with in-plane compartmental sizes obtained from histopathology analysis of step-sectioned prostatectomy specimens; 2) Gauge the ability of a reader to plan an interstitial focal treatment using MRI. This was accomplished by objective measures of contrast and volume measurement with subjective reader analysis of tumor conspicuities; 3) Evaluation of the early biologic response to 186Re interstitial focal therapy. This was achieved by correlation of histochemistry (HC) markers: hetrochromatin protein alpha (HP1α), cluster of differentiation 34 (CD34), terminal deoxynucleotidal transferase nick end labeling (TUNEL), caspase 3, Ki-67 and hematoxylin & eosin (H&E) to the radiation distribution as seen on AR and radiation absorbed dose as computed from planar imaging. The conclusions of this study are that prostate MRI allows targeting of appropriate lesions for therapy by its ability to inform on the tumor microenvironment. MRI distinguishes prostatic tumors on the basis of tissue composition. Readers are better able reproduce volumes and thus plan interstitial therapy for tumors which have a denser, more homogeneous composition. The combination of SPECT and autoradiography showed a dose and position dependent expression of HC markers. These results demonstrate that multimodality imaging is capable of targeting, planning and evaluating interstitial focal therapy.

Inhibition of Necroptosis Attenuates Kidney Inflammation and Interstitial Fibrosis Induced By Unilateral Ureteral Obstruction.

PubMed

Xiao, Xia; Du, Chunyang; Yan, Zhe; Shi, Yonghong; Duan, Huijun; Ren, Yunzhuo

2017-01-01

Inflammation plays a crucial role in renal interstitial fibrosis, the pathway of chronic kidney diseases. Necroptosis is a novel form of regulated cell death, which plays a potential role in inflammation and renal diseases. The small molecule necrostatin-1 (Nec-1) is a specific inhibitor of necroptosis. This study was aimed at determining the role of necroptosis, RIP1/RIP3/mixed lineage kinase domain-like (MLKL) signaling pathway, in renal inflammation and interstitial fibrosis related to primitive tubulointerstitial injury. It was also aimed at evaluating the effect of Nec-1 in renal fibrosis induced by unilateral ureteral obstruction (UUO). Renal histology, immunohistochemistry, western blot, and real-time polymerase chain reaction were performed using UUO C57BL/6J mice model. Moreover, we tested whether Nec-1 was renal-protective in the interstitial fibrosis kidney. Mice were exposed to UUO and injected intraperitoneal with Nec-1 or vehicle. The levels of RIP1/RIP3/MLKL protein and mRNA were increased in the obstructed kidneys 7 days after UUO; this was accompanied by changes in renal pathological lesions. Renal histological examination showed lesser renal damage in Nec-1-treated UUO mice. Renal inflammation, assessed by tumor necrosis factor-α, interleukin-1β, and monocyte chemotactic protein-1 was markedly attenuated by Nec-1. Furthermore, Nec-1 treatment also significantly reduced TGF-β and α-smooth muscle actin, indicating lesser renal interstitial fibrosis. These findings suggest that the participation of necroptosis in UUO is partly demonstrated. And necroptosis inhibition may have a potential role in the treatment of diseases with increased inflammatory response and interstitial fibrosis in renal. © 2017 S. Karger AG, Basel.

AB INITIO calculation of the electromigration wind valence of interstitial hydrogen in f.c.c metals

NASA Astrophysics Data System (ADS)

van Ek, J.; Lodder, A.

1990-02-01

Calculated electromigration wind valences, obtained within a KKR-Green function description, are presented. It is shown that the electromigration wind valence of hydrogen along different migration paths in Cu, Ag and Pd can be calculated including charge transfer effects in the impurity cluster. A nice procedure for retrieving the scalar character of the wind valence in an f.c.c metal introduces an explanation for the isotope effect in the wind valence.

Role of lipids in the progression of renal disease in systemic lupus erythematosus patients.

PubMed

Luzar, B; Ferluga, D

2000-08-25

Systemic lupus erythematosus (SLE) is an autoimmune connective tissue disease marked by immune-complex mediated lesions in small blood vessels of various organs, especially the kidneys, although other factors may also be implicated in the pathogenesis of the disease. This article focuses on the role of lipids in the progression of glomerular, vascular and tubulo-interstitial lesions in two patients with lupus nephritis associated with pronounced hyper- and dyslipidemia. The pathogenesis of progressive glomerulosclerosis in both patients appears to be multifactorial. In addition to immune complex mediated lupus glomerulonephritis, progressively active in the first patient, severe nephrotic-range persistent proteinuria, arterial hypertension associated with hyperfiltration and hyperperfusion injuries and, to a minor extent, hyper- and dyslipidemia were observed. Immunological and non-immunological factors were shown to contribute to the development of tubulo-interstitial lesions. In both patients, in addition to local immune deposits, prominent tubulo-interstitial lipid deposits were probably causally related to both hyperlipidemia and the increased permeability of the glomerular filtration barrier. Tubular lesions were highlighted by intracytoplasmic lipid droplets as well as small cleft-like spaces found to be impacted in the tubular lumina. They were seen to penetrate tubular epithelial cells and eventually lodge in the interstitium, surrounded by mononuclear cell infiltrates and foam cells. In both patients, hypertensive angiopathy and extraglomerular vascular immune deposits were demonstrated. In addition, in the second patient, arteriolar and small arterial hyaline was found at the age of 28 years to be full of lipids and calcium precipitates, suggesting a peripheral atherosclerosis-like process which never occurs as a natural age-related condition. In conclusion, all parts of the nephron may be involved in the pathogenetic process causally related or influenced by hyper- or dyslipidemia. Associated either with endothelial cell injury and consequent insudation of lipids in the vascular walls, glomerular filtration barrier injury with hyperfiltration, or tubulo-interstitial lipid deposition, the mechanism of tissue damage by lipids in all parts of the nephron shares similarities with the pathogenesis of systemic atherosclerosis.

Alagille syndrome with deletion 20p12.2-p12.3 and hypoplastic left heart.

PubMed

Robert, Marie Leema P; Lopez, Tony; Crolla, John; Huang, Shuwen; Owen, Carol; Burvill-Holmes, Lisa; Stumper, Oliver; Turnpenny, Peter D

2007-10-01

We report a male patient born at 37-weeks gestation, weighing 1.885 kg (<0.4th centile). Shortly after birth, he was diagnosed with hypoplastic left heart syndrome for which he underwent a Norwood procedure. Subsequently, he developed problems with failure to thrive and developmental delay. At the age of 4 years his delay in growth and development led to further investigations, which revealed a small de-novo interstitial deletion of chromosome 20p12.2. JAGGED1 haploinsufficiency was confirmed by fluorescence in situ hybridization. Array-comparative genomic hybridization analysis confirmed and quantified an approximate 5.4 Mb interstitial deletion involving the chromosomal region 20p12.2-p12.3. This precise interstitial deletion has not been previously reported. Further clinical evaluation revealed posterior embryotoxon and butterfly vertebrae. He has normal liver function tests, facial features consistent with Alagille syndrome, and mild learning difficulties. To our knowledge this is the first report of Alagille syndrome associated with hypoplastic left heart syndrome.

Clinical phenotypes and survival of pre-capillary pulmonary hypertension in systemic sclerosis.

PubMed

Launay, David; Montani, David; Hassoun, Paul M; Cottin, Vincent; Le Pavec, Jérôme; Clerson, Pierre; Sitbon, Olivier; Jaïs, Xavier; Savale, Laurent; Weatherald, Jason; Sobanski, Vincent; Mathai, Stephen C; Shafiq, Majid; Cordier, Jean-François; Hachulla, Eric; Simonneau, Gérald; Humbert, Marc

2018-01-01

Pre-capillary pulmonary hypertension (PH) in systemic sclerosis (SSc) is a heterogeneous condition with an overall bad prognosis. The objective of this study was to identify and characterize homogeneous phenotypes by a cluster analysis in SSc patients with PH. Patients were identified from two prospective cohorts from the US and France. Clinical, pulmonary function, high-resolution chest tomography, hemodynamic and survival data were extracted. We performed cluster analysis using the k-means method and compared survival between clusters using Cox regression analysis. Cluster analysis of 200 patients identified four homogenous phenotypes. Cluster C1 included patients with mild to moderate risk pulmonary arterial hypertension (PAH) with limited or no interstitial lung disease (ILD) and low DLCO with a 3-year survival of 81.5% (95% CI: 71.4-88.2). C2 had pre-capillary PH due to extensive ILD and worse 3-year survival compared to C1 (adjusted hazard ratio [HR] 3.14; 95% CI 1.66-5.94; p = 0.0004). C3 had severe PAH and a trend towards worse survival (HR 2.53; 95% CI 0.99-6.49; p = 0.052). Cluster C4 and C1 were similar with no difference in survival (HR 0.65; 95% CI 0.19-2.27, p = 0.507) but with a higher DLCO in C4. PH in SSc can be characterized into distinct clusters that differ in prognosis.

A study of the effect of helium concentration and displacement damage on the microstructure of helium ion irradiated tungsten

NASA Astrophysics Data System (ADS)

Harrison, R. W.; Greaves, G.; Hinks, J. A.; Donnelly, S. E.

2017-11-01

Transmission electron microscopy (TEM) with in-situ He ion irradiation has been used to examine the damage microstructure of W when varying the helium concentration to displacement damage ratio, irradiation temperature and total dose. Irradiations employed 15, 60 or 85 keV He ions, at temperatures between 500 and 1000 °C up to doses of ∼3.0 DPA. Once nucleated and grown to an observable size in the TEM, bubble diameter as a function of irradiation dose did not measurably increase at irradiation temperatures of 500 °C between 1.0 and 3.0 DPA; this is attributed to the low mobility of vacancies and He/vacancy complexes at these temperatures. Bubble diameter increased slightly for irradiation temperatures of 750 °C and rapidly increased when irradiated at 1000 °C. Dislocation loops were observed at irradiation temperatures of 500 and 750 °C and no loops were observed at 1000 °C. Burgers vectors of the dislocations were determined to be b = ±½<111> type only and both vacancy and interstitial loops were observed. The proportion of interstitial loops increased with He-appm/DPA ratio and this is attributed to the concomitant increase in bubble areal density, which reduces the vacancy flux for both the growth of vacancy-type loops and the annihilation of interstitial clusters.

Smoking-related interstitial fibrosis combined with pulmonary emphysema: computed tomography-pathologic correlative study using lobectomy specimens

PubMed Central

Otani, Hideji; Tanaka, Tomonori; Murata, Kiyoshi; Fukuoka, Junya; Nitta, Norihisa; Nagatani, Yukihiro; Sonoda, Akinaga; Takahashi, Masashi

2016-01-01

Purpose To evaluate the incidence and pathologic correlation of thin-section computed tomography (TSCT) findings in smoking-related interstitial fibrosis (SRIF) with pulmonary emphysema. Patients and methods Our study included 172 consecutive patients who underwent TSCT and subsequent lobectomy. TSCT findings including clustered cysts with visible walls (CCVW) and ground-glass attenuation with/without reticulation (GGAR) were evaluated and compared in nonsmokers and smokers and among lung locations. TSCT findings, especially CCVW, were also compared with histological findings using lobectomy specimens. Results The incidence of CCVW and GGAR was significantly higher in smokers than in nonsmokers (34.1% and 40.7%, respectively, vs 2.0% and 12.2%). CCVW and GGAR were frequently found in the lower and peripheral zones. Histologically, CCVW corresponded more often with SRIF with emphysema than usual interstitial pneumonia (UIP, 63.3% vs 30%). CCVW of irregular size and shape were seen in 19 of 20 SRIF with emphysema and in seven of nine UIP-manifested areas with similar round cysts. A less-involved subpleural parenchyma was observed more frequently in SRIF with emphysema. Conclusion SRIF with emphysema is a more frequent pathological finding than UIP in patients with CCVW on TSCT. The irregular size and shape of CCVW and a less-involved subpleural parenchyma may be a clue suggesting the presence of SRIF with emphysema. PMID:27445472

Rare variants in RTEL1 are associated with familial interstitial pneumonia.

PubMed

Cogan, Joy D; Kropski, Jonathan A; Zhao, Min; Mitchell, Daphne B; Rives, Lynette; Markin, Cheryl; Garnett, Errine T; Montgomery, Keri H; Mason, Wendi R; McKean, David F; Powers, Julia; Murphy, Elissa; Olson, Lana M; Choi, Leena; Cheng, Dong-Sheng; Blue, Elizabeth Marchani; Young, Lisa R; Lancaster, Lisa H; Steele, Mark P; Brown, Kevin K; Schwarz, Marvin I; Fingerlin, Tasha E; Schwartz, David A; Lawson, William E; Loyd, James E; Zhao, Zhongming; Phillips, John A; Blackwell, Timothy S

2015-03-15

Up to 20% of cases of idiopathic interstitial pneumonia cluster in families, comprising the syndrome of familial interstitial pneumonia (FIP); however, the genetic basis of FIP remains uncertain in most families. To determine if new disease-causing rare genetic variants could be identified using whole-exome sequencing of affected members from FIP families, providing additional insights into disease pathogenesis. Affected subjects from 25 kindreds were selected from an ongoing FIP registry for whole-exome sequencing from genomic DNA. Candidate rare variants were confirmed by Sanger sequencing, and cosegregation analysis was performed in families, followed by additional sequencing of affected individuals from another 163 kindreds. We identified a potentially damaging rare variant in the gene encoding for regulator of telomere elongation helicase 1 (RTEL1) that segregated with disease and was associated with very short telomeres in peripheral blood mononuclear cells in 1 of 25 families in our original whole-exome sequencing cohort. Evaluation of affected individuals in 163 additional kindreds revealed another eight families (4.7%) with heterozygous rare variants in RTEL1 that segregated with clinical FIP. Probands and unaffected carriers of these rare variants had short telomeres (<10% for age) in peripheral blood mononuclear cells and increased T-circle formation, suggesting impaired RTEL1 function. Rare loss-of-function variants in RTEL1 represent a newly defined genetic predisposition for FIP, supporting the importance of telomere-related pathways in pulmonary fibrosis.

Electron Microscopic Observations of the Carotid Body of the Cat

PubMed Central

Ross, Leonard L.

1959-01-01

Carotid bodies were removed from cats, fixed in buffered 1 per cent osmic acid, embedded in deaerated, nitrogenated methacrylate, and cut into thin sections for electron microscopic study. The carotid body is seen to be composed of islands of chemoreceptor and sustentacular cells surrounded by wide irregular sinusoids. These cells are separated from the sinusoids by relatively broad interstitial spaces which are filled with collagen, fibroblasts, and many unmyelinated nerve fibers with their Schwann cell sheaths. The chemoreceptor cells are surrounded by the flattened, multiprocessed sustentacular cells which serve to convey the axons from an interstitial to a pericellular location. These sustentacular cells are assumed to be lemmoblastic in origin. Relatively few axons are seen to abut on the chemoreceptor cells. The cytoplasm of the chemoreceptor cell is characterized by numerous small mitochondria, units of granular endoplasmic reticulum, a small Golgi complex, and a variety of vesicles. There are many small vesicles diffusely scattered throughout the cytoplasm. In addition, there is a small number of dark-cored vesicles of the type which has been previously described in the adrenal medulla. These are usually associated with the Golgi complex. These findings are discussed in relation to the concepts of the origin of the chemoreceptor cell and the nature of the synapse. PMID:14439171

Role of interstitial branching in the development of visual corticocortical connections: a time-lapse and fixed-tissue analysis.

PubMed

Ruthazer, Edward S; Bachleda, Amelia R; Olavarria, Jaime F

2010-12-15

We combined fixed-tissue and time-lapse analyses to investigate the axonal branching phenomena underlying the development of topographically organized ipsilateral projections from area 17 to area 18a in the rat. These complementary approaches allowed us to relate static, large-scale information provided by traditional fixed-tissue analysis to highly dynamic, local, small-scale branching phenomena observed with two-photon time-lapse microscopy in acute slices of visual cortex. Our fixed-tissue data revealed that labeled area 17 fibers invaded area 18a gray matter at topographically restricted sites, reaching superficial layers in significant numbers by postnatal day 6 (P6). Moreover, most parental axons gave rise to only one or occasionally a small number of closely spaced interstitial branches beneath 18a. Our time-lapse data showed that many filopodium-like branches emerged along parental axons in white matter or deep layers in area 18a. Most of these filopodial branches were transient, often disappearing after several minutes to hours of exploratory extension and retraction. These dynamic behaviors decreased significantly from P4, when the projection is first forming, through the second postnatal week, suggesting that the expression of, or sensitivity to, cortical cues promoting new branch addition in the white matter is developmentally down-regulated coincident with gray matter innervation. Together, these data demonstrate that the development of topographically organized corticocortical projections in rats involves extensive exploratory branching along parental axons and invasion of cortex by only a small number of interstitial branches, rather than the widespread innervation of superficial cortical layers by an initially exuberant population of branches. © 2010 Wiley-Liss, Inc.

Role of Interstitial Branching in the Development of Visual Corticocortical Connections: A Time-Lapse and Fixed-Tissue Analysis

PubMed Central

Ruthazer, Edward S.; Bachleda, Amelia R.; Olavarria, Jaime F.

2013-01-01

We combined fixed-tissue and time-lapse analyses to investigate the axonal branching phenomena underlying the development of topographically organized ipsilateral projections from area 17 to area 18a in the rat. These complementary approaches allowed us to relate static, large-scale information provided by traditional fixed-tissue analysis to highly dynamic, local, small-scale branching phenomena observed with two-photon time-lapse microscopy in acute slices of visual cortex. Our fixed-tissue data revealed that labeled area 17 fibers invaded area 18a gray matter at topographically restricted sites, reaching superficial layers in significant numbers by postnatal day 6 (P6). Moreover, most parental axons gave rise to only one or occasionally a small number of closely spaced interstitial branches beneath 18a. Our time-lapse data showed that many filopodium-like branches emerged along parental axons in white matter or deep layers in area 18a. Most of these filopo-dial branches were transient, often disappearing after several minutes to hours of exploratory extension and retraction. These dynamic behaviors decreased significantly from P4, when the projection is first forming, through the second postnatal week, suggesting that the expression of, or sensitivity to, cortical cues promoting new branch addition in the white matter is developmentally down-regulated coincident with gray matter innervation. Together, these data demonstrate that the development of topographically organized corticocortical projections in rats involves extensive exploratory branching along parental axons and invasion of cortex by only a small number of interstitial branches, rather than the widespread innervation of superficial cortical layers by an initially exuberant population of branches. PMID:21031561

SBA Innovation Clusters

DTIC Science & Technology

2012-03-02

Programs and services to help you start, grow and succeed www.sba.gov U.S. Small Business Administration Your Small Business Resource 1Approved for...Public Release SBA Innovation Clusters RADM Steven G. Smith USN (Ret) Advanced Defense Technology Cluster Coordinator U.S. Small Business ...UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) U.S. Small Business Administration ,Advanced Defense Technology Cluster,409 3rd St, SW

Immunohistochemical detection of virus through its nuclear cytopathic effect in idiopathic interstitial pneumonia other than acute exacerbation

PubMed Central

dos Santos, G.C.; Parra, E.R.; Stegun, F.W.; Cirqueira, C.S.; Capelozzi, V.L.

2013-01-01

Idiopathic interstitial pneumonias include complex diseases that have a strong interaction between genetic makeup and environmental factors. However, in many cases, no infectious agent can be demonstrated, and these clinical diseases rapidly progress to death. Theoretically, idiopathic interstitial pneumonias could be caused by the Epstein-Barr virus, cytomegalovirus, adenovirus, hepatitis C virus, respiratory syncytial virus, and herpesvirus, which may be present in such small amounts or such configuration that routine histopathological analysis or viral culture techniques cannot detect them. To test the hypothesis that immunohistochemistry provides more accurate results than the mere histological demonstration of viral inclusions, this method was applied to 37 open lung biopsies obtained from patients with idiopathic interstitial pneumonias. As a result, immunohistochemistry detected measles virus and cytomegalovirus in diffuse alveolar damage-related histological patterns of acute exacerbation of idiopathic pulmonary fibrosis and nonspecific interstitial pneumonia in 38 and 10% of the cases, respectively. Alveolar epithelium infection by cytomegalovirus was observed in 25% of organizing pneumonia patterns. These findings were coincident with nuclear cytopathic effects but without demonstration of cytomegalovirus inclusions. These data indicate that diffuse alveolar damage-related cytomegalovirus or measles virus infections enhance lung injury, and a direct involvement of these viruses in diffuse alveolar damage-related histological patterns is likely. Immunohistochemistry was more sensitive than the histological demonstration of cytomegalovirus or measles virus inclusions. We concluded that all patients with diffuse alveolar damage-related histological patterns should be investigated for cytomegalovirus and measles virus using sensitive immunohistochemistry in conjunction with routine procedures. PMID:24270907

Robustness of cluster synchronous patterns in small-world networks with inter-cluster co-competition balance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Jianbao; Ma, Zhongjun, E-mail: mzj1234402@163.com; Chen, Guanrong

All edges in the classical Watts and Strogatz's small-world network model are unweighted and cooperative (positive). By introducing competitive (negative) inter-cluster edges and assigning edge weights to mimic more realistic networks, this paper develops a modified model which possesses co-competitive weighted couplings and cluster structures while maintaining the common small-world network properties of small average shortest path lengths and large clustering coefficients. Based on theoretical analysis, it is proved that the new model with inter-cluster co-competition balance has an important dynamical property of robust cluster synchronous pattern formation. More precisely, clusters will neither merge nor split regardless of adding ormore » deleting nodes and edges, under the condition of inter-cluster co-competition balance. Numerical simulations demonstrate the robustness of the model against the increase of the coupling strength and several topological variations.« less

Robustness of cluster synchronous patterns in small-world networks with inter-cluster co-competition balance

NASA Astrophysics Data System (ADS)

Zhang, Jianbao; Ma, Zhongjun; Chen, Guanrong

2014-06-01

All edges in the classical Watts and Strogatz's small-world network model are unweighted and cooperative (positive). By introducing competitive (negative) inter-cluster edges and assigning edge weights to mimic more realistic networks, this paper develops a modified model which possesses co-competitive weighted couplings and cluster structures while maintaining the common small-world network properties of small average shortest path lengths and large clustering coefficients. Based on theoretical analysis, it is proved that the new model with inter-cluster co-competition balance has an important dynamical property of robust cluster synchronous pattern formation. More precisely, clusters will neither merge nor split regardless of adding or deleting nodes and edges, under the condition of inter-cluster co-competition balance. Numerical simulations demonstrate the robustness of the model against the increase of the coupling strength and several topological variations.

Density-based clustering of small peptide conformations sampled from a molecular dynamics simulation.

PubMed

Kim, Minkyoung; Choi, Seung-Hoon; Kim, Junhyoung; Choi, Kihang; Shin, Jae-Min; Kang, Sang-Kee; Choi, Yun-Jaie; Jung, Dong Hyun

2009-11-01

This study describes the application of a density-based algorithm to clustering small peptide conformations after a molecular dynamics simulation. We propose a clustering method for small peptide conformations that enables adjacent clusters to be separated more clearly on the basis of neighbor density. Neighbor density means the number of neighboring conformations, so if a conformation has too few neighboring conformations, then it is considered as noise or an outlier and is excluded from the list of cluster members. With this approach, we can easily identify clusters in which the members are densely crowded in the conformational space, and we can safely avoid misclustering individual clusters linked by noise or outliers. Consideration of neighbor density significantly improves the efficiency of clustering of small peptide conformations sampled from molecular dynamics simulations and can be used for predicting peptide structures.

Analysis of pulsed-neutron powder diffraction patterns of the icosahedral quasicrystals Pd3Siu and AlCuLiMg (three alloys) as twinned cubic crystals with large units.

PubMed Central

Pauling, L

1991-01-01

The low-Q peaks on three pulsed-neutron powder patterns (total, U differential, and Pd differential) of the icosahedral quasicrystal Pd3SiU have been indexed on the basis of an assumed cubic structure of the crystals that by icosahedral twinning form the quasicrystal. The primitive unit cube is found to have edge length 56.20 A and to contain approximately 12,100 atoms. Similar analyses of pulsed-neutron patterns of Al55Cu10Li35, Al55Cu10Li30Mg5, and Al510Cu125Li235Mg130 give values of the cube edge length 58.3, 58.5, and 58.4 A, respectively, with approximately 11,650 atoms in the unit cube. It is suggested that the unit contains eight complexes in the beta-W positions, plus some small interstitial groups of atoms, with each complex consisting of a centered icosahedron of 13 clusters, each of 116 atoms with the icosahedral structure found in the body-centered cubic crystal Mg32(Al,Zn)49. PMID:11607201

Analysis of pulsed-neutron powder diffraction patterns of the icosahedral quasicrystals Pd3Siu and AlCuLiMg (three alloys) as twinned cubic crystals with large units.

PubMed

Pauling, L

1991-08-01

The low-Q peaks on three pulsed-neutron powder patterns (total, U differential, and Pd differential) of the icosahedral quasicrystal Pd3SiU have been indexed on the basis of an assumed cubic structure of the crystals that by icosahedral twinning form the quasicrystal. The primitive unit cube is found to have edge length 56.20 A and to contain approximately 12,100 atoms. Similar analyses of pulsed-neutron patterns of Al55Cu10Li35, Al55Cu10Li30Mg5, and Al510Cu125Li235Mg130 give values of the cube edge length 58.3, 58.5, and 58.4 A, respectively, with approximately 11,650 atoms in the unit cube. It is suggested that the unit contains eight complexes in the beta-W positions, plus some small interstitial groups of atoms, with each complex consisting of a centered icosahedron of 13 clusters, each of 116 atoms with the icosahedral structure found in the body-centered cubic crystal Mg32(Al,Zn)49.

An integrated approach in the diagnosis of smoking-related interstitial lung diseases.

PubMed

Caminati, Antonella; Cavazza, Alberto; Sverzellati, Nicola; Harari, Sergio

2012-09-01

Cigarette smoke consists of several chemical compounds with a variety of effects in many organs. In the lung, apart being the main cause of chronic obstructive pulmonary disease, carcinoma and idiopathic spontaneous pneumothorax, tobacco smoke is associated with interstitial lung diseases (ILDs), including respiratory bronchiolitis-associated ILD (RB-ILD), desquamative interstitial pneumonia (DIP), pulmonary Langerhans' cell histiocytosis (PLCH), idiopathic pulmonary fibrosis, acute eosinophilic pneumonia, ILD in rheumatoid arthritis and pulmonary haemorrhage in Goodpasture syndrome. This review will focus on the diseases with a stronger epidemiological association with tobacco smoke, namely RB-ILD, DIP and PLCH. Although the exact pathogenetic evidence linking smoking with these disorders is still not completely understood, there is growing evidence that tobacco smoke targets the terminal or respiratory bronchioles in these diseases, and the differences are reflective of the degree of severity of small airway and parenchymal reaction to the smoke exposure. Despite considerable clinical, radiological and histological overlap between RB-ILD, DIP and PLCH, it is useful to retain the separate classifications for prognostic and therapeutic implications.

Early interstitial lung disease in microscopic polyangiitis: Case report and literature review.

PubMed

García-Nava, Marcos; Mateos-Toledo, Heidegger; Guevara-Canseco, Ana Patricia Georgina; Infante-González, Cesar Eduardo; Reyes-Nava, Diego Alberto; Estrada-Castro, Emilio

Microscopic polyangiitis (MPA) is a systemic disease included in the Chapel Hill 2012 Classification as necrotizing vasculitis affecting capillaries, venules and arterioles. It usually expresses antineutrophil cytoplasmic antibodies (ANCA) and has a perinuclear immunofluorescence pattern and correlation with anti-myeloperoxidase (MPO) antibodies. Capillaritis with alveolar hemorrhage is the most common manifestation of lung disease. Interstitial lung disease (ILD) is uncommon, with usual interstitial pneumonia being the predominant pattern. However, other patterns such as organizing pneumonia have been described. No guidelines exist for treating patients with ILD and, currently, ANCA-associated vasculitis (AAV) is managed along the lines of small vessel vasculitis. The prognosis with this association is uncertain, with possibilities of relapse and a fatal outcome. We present a case in which ILD was the first manifestation of MPA, without alveolar hemorrhage, with subsequent renal involvement and, in which, the established treatment produced a significant clinical improvement. Copyright © 2016 Elsevier España, S.L.U. and Sociedad Española de Reumatología y Colegio Mexicano de Reumatología. All rights reserved.

Interstitial lung disease induced by alectinib (CH5424802/RO5424802).

PubMed

Ikeda, Satoshi; Yoshioka, Hiroshige; Arita, Machiko; Sakai, Takahiro; Sone, Naoyuki; Nishiyama, Akihiro; Niwa, Takashi; Hotta, Machiko; Tanaka, Tomohiro; Ishida, Tadashi

2015-02-01

A 75-year-old woman with anaplastic lymphoma kinase (ALK)-rearranged Stage IV lung adenocarcinoma was administered the selective anaplastic lymphoma kinase inhibitor, alectinib, as a third-line treatment in a Phase 1-2 study. On the 102nd day, chest computed tomography showed diffuse ground glass opacities. Laboratory data revealed high serum levels of KL-6, SP-D and lactate dehydrogenase without any clinical symptoms. There was no evidence of infection. Marked lymphocytosis was seen in bronchoalveolar lavage fluid analysis, and transbronchial lung biopsy showed mild thickening of alveolar septa and lymphocyte infiltration. Interstitial lung disease was judged to be related to alectinib based on improvements in imaging findings and serum biomarkers after discontinuation of alectinib. To our knowledge, this is the first reported case of alectinib-induced interstitial lung disease. Alectinib is a promising drug for ALK-rearranged non-small cell lung cancer. Clinical trials of this selective anaplastic lymphoma kinase inhibitor will facilitate the meticulous elucidation of its long-term safety profile. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Evidence for independent motional processes on the two interstitial sublattices of a layer-structured metal hydride: Hydrogen spin-lattice relaxation and motional narrowing in zirconium monohalide hemihydrides, ZrXH0.5

NASA Astrophysics Data System (ADS)

Hwang, T. Y.; Schoenberger, R. J.; Torgeson, D. R.; Barnes, R. G.

1983-01-01

We report the results of a proton-magnetic-resonance investigation of hydrogen location and motion in the hemihydrides ZrXH0.5 of the metallic layer-structured monohalides ZrX of zirconium (X=Br,Cl). Wide-line and pulsed NMR methods were employed to measure the temperature dependence of the linewidth and second moment and of the spin-lattice relaxation time in the laboratory and rotating frames. The results indicate that hydrogen forms an ordered structure on the tetrahedral (T) interstitial sublattice within the Zr metal bilayers, with some (small) random occupancy of octahedral (O) sites. Two stages of motional narrowing observed in the wide-line measurements and double minima found in the relaxation times are consistent with the occurrence of essentially independent hydrogen motional processes on the T and O interstitial sublattices. Hydrogen site occupancy probabilities, jump frequencies, activation energies for hydrogen diffusion, and conduction-electron contributions to the proton spin-lattice relaxation rate are deduced from the measurements.

Rare Variants in RTEL1 Are Associated with Familial Interstitial Pneumonia

PubMed Central

Cogan, Joy D.; Zhao, Min; Mitchell, Daphne B.; Rives, Lynette; Markin, Cheryl; Garnett, Errine T.; Montgomery, Keri H.; Mason, Wendi R.; McKean, David F.; Powers, Julia; Murphy, Elissa; Olson, Lana M.; Choi, Leena; Cheng, Dong-Sheng; Blue, Elizabeth Marchani; Young, Lisa R.; Lancaster, Lisa H.; Steele, Mark P.; Brown, Kevin K.; Schwarz, Marvin I.; Fingerlin, Tasha E.; Schwartz, David A.; Lawson, William E.; Loyd, James E.; Zhao, Zhongming; Phillips, John A.; Blackwell, Timothy S.

2015-01-01

Rationale: Up to 20% of cases of idiopathic interstitial pneumonia cluster in families, comprising the syndrome of familial interstitial pneumonia (FIP); however, the genetic basis of FIP remains uncertain in most families. Objectives: To determine if new disease-causing rare genetic variants could be identified using whole-exome sequencing of affected members from FIP families, providing additional insights into disease pathogenesis. Methods: Affected subjects from 25 kindreds were selected from an ongoing FIP registry for whole-exome sequencing from genomic DNA. Candidate rare variants were confirmed by Sanger sequencing, and cosegregation analysis was performed in families, followed by additional sequencing of affected individuals from another 163 kindreds. Measurements and Main Results: We identified a potentially damaging rare variant in the gene encoding for regulator of telomere elongation helicase 1 (RTEL1) that segregated with disease and was associated with very short telomeres in peripheral blood mononuclear cells in 1 of 25 families in our original whole-exome sequencing cohort. Evaluation of affected individuals in 163 additional kindreds revealed another eight families (4.7%) with heterozygous rare variants in RTEL1 that segregated with clinical FIP. Probands and unaffected carriers of these rare variants had short telomeres (<10% for age) in peripheral blood mononuclear cells and increased T-circle formation, suggesting impaired RTEL1 function. Conclusions: Rare loss-of-function variants in RTEL1 represent a newly defined genetic predisposition for FIP, supporting the importance of telomere-related pathways in pulmonary fibrosis. PMID:25607374

High-intensity intermittent exercise increases pulmonary interstitial edema at altitude but not at simulated altitude.

PubMed

Edsell, Mark E; Wimalasena, Yashvi H; Malein, William L; Ashdown, Kimberly M; Gallagher, Carla A; Imray, Chris H; Wright, Alex D; Myers, Stephen D

2014-12-01

Ascent to high altitude leads to a reduction in ambient pressure and a subsequent fall in available oxygen. The resulting hypoxia can lead to elevated pulmonary artery (PA) pressure, capillary stress, and an increase in interstitial fluid. This fluid can be assessed on lung ultrasound (LUS) by the presence of B-lines. We undertook a chamber and field study to assess the impact of high-intensity exercise in hypoxia on the development of pulmonary interstitial edema in healthy lowlanders. Thirteen volunteers completed a high-intensity intermittent exercise (HIIE) test at sea level, in acute normobaric hypoxia (12% O2, approximately 4090 m equivalent altitude), and in hypobaric hypoxia during a field study at 4090 m after 6 days of acclimatization. Pulmonary interstitial edema was assessed by the evaluation of LUS B-lines. After HIIE, no increase in B-lines was seen in normoxia, and a small increase was seen in acute normobaric hypoxia (2 ± 2; P < .05). During the field study at 4090 m, 12 participants (92%) demonstrated 7 ± 4 B-lines at rest, which increased to 17 ± 5 immediately after the exercise test (P < .001). An increase was evident in all participants. There was a reciprocal fall in peripheral arterial oxygen saturations (Spo2) after exercise from 88% ± 4% to 80% ± 8% (P < .01). B-lines and Spo2 in all participants returned to baseline levels within 4 hours. HIIE led to an increase in B-lines at altitude after subacute exposure but not during acute exposure at equivalent simulated altitude. This may indicate pulmonary interstitial edema. Copyright © 2014 Wilderness Medical Society. Published by Elsevier Inc. All rights reserved.

Velo-cardio-facial and partial DiGeorge phenotype in a child with interstitial deletion at 10p13 - implications for cytogenetics and molecular biology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lipson, A.; Sholler, G.; Issacs, D.

We report on a female with a interstitial deletion of 10p13 and a phenotype similar to that seen with the 22q deletion syndromes (DiGeorge/velo-cardio-facial). She had a posterior cleft palate, perimembranous ventricular septal defect, dyscoordinate swallowing, T-cell subset abnormalities, small ears, maxillary and mandibular hypoplasia, broad nasal bridge, deficient alae nasi, contractures of fingers and developmental delay. This could indicate homology of some developmental genes at 22q and 10p so that patients with the velocardiofacial phenotype who do not prove to be deleted on 22q are candidates for a 10p deletion. 58 refs., 3 figs.

Dynamic behaviour of nanometre-sized defect clusters emitted from an atomic displacement cascade in Au at 50 K

NASA Astrophysics Data System (ADS)

Ono, K.; Miyamoto, M.; Arakawa, K.; Birtcher, R. C.

2017-09-01

We demonstrate the emission of nanometre-sized defect clusters from an isolated displacement cascade formed by irradiation of high-energy self-ions and their subsequent 1-D motion in Au at 50 K, using in situ electron microscopy. The small defect clusters emitted from a displacement cascade exhibited correlated back-and-forth 1-D motion along the [-1 1 0] direction and coalescence which results in their growth and reduction of their mobility. From the analysis of the random 1-D motion, the diffusivity of the small cluster was evaluated. Correlated 1-D motion and coalescence of clusters were understood via elastic interaction between small clusters. These results provide direct experimental evidence of the migration of small defect clusters and defect cascade evolution at low temperature.

Diffusion and recrystallization of B implanted in crystalline and pre-amorphized Ge in the presence of F

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hsu, William, E-mail: william.hsu@utexas.edu; Kim, Taegon; Chou, Harry

2016-07-07

Although the diffusion control and dopant activation of Ge p-type junctions are straightforward when using B{sup +} implantation, the use of the heavier BF{sub 2}{sup +} ions or even BF{sup +} is still favored in terms of shallow junction formation and throughput—because implants can be done at higher energies, which can give higher beam currents and beam stability—and thus the understanding of the effect of F co-doping becomes important. In this work, we have investigated diffusion and end-of-range (EOR) defect formation for B{sup +}, BF{sup +}, and BF{sub 2}{sup +} implants in crystalline and pre-amorphized Ge, employing rapid thermal annealingmore » at 600 °C and 800 °C for 10 s. It is demonstrated that the diffusion of B is strongly influenced by the temperature, the presence of F, and the depth of amorphous/crystalline interface. The B and F diffusion profiles suggest the formation of B–F complexes and enhanced diffusion by interaction with point defects. In addition, the strong chemical effect of F is found only for B in Ge, while such an effect is vanishingly small for samples implanted with F alone, or co-implanted with P and F, as evidenced by the high residual F concentration in the B-doped samples after annealing. After 600 °C annealing for 10 s, interstitial-induced compressive strain was still observed in the EOR region for the sample implanted with BF{sup +}, as measured by X-ray diffraction. Further analysis by cross-sectional transmission electron microscopy showed that the {311} interstitial clusters are the majority type of EOR defects. The impact of these {311} defects on the electrical performance of Ge p{sup +}/n junctions formed by BF{sup +} implantation was evaluated.« less

Thermal desorption behavior of helium in aged titanium tritide films

NASA Astrophysics Data System (ADS)

Cheng, G. J.; Shi, L. Q.; Zhou, X. S.; Liang, J. H.; Wang, W. D.; Long, X. G.; Yang, B. F.; Peng, S. M.

2015-11-01

The desorption behavior of helium in TiT(1.5∼1.8)-x3Hex film samples (x = 0.0022-0.22) was investigated by thermal desorption technique in vacuum condition in this paper. The thermal helium desorption spectrometry (THDS) of aging titanium tritide films prepared by electron beam evaporation revealed that, depending on the decayed 3He concentration in the samples, there are more than four states of helium existing in the films. The divided four zones in THDS based on helium states represent respectively: (1) the mobile single helium atoms with low activation energy in all aging samples resulted from the interstitial sites or dissociated from interstitial clusters, loops and dislocations, (2) helium bubbles inside the grain lattices, (3) helium bubbles in the grain boundaries and interconnected networks of dislocations in the helium concentration of 3Hegen/Ti > 0.0094, and (4) helium bubbles near or linked to the film surface by interconnected channel for later aging stage with 3Hegen/Ti > 0.18. The proportion of helium desorption in each zone was estimated, and dissociated energies of helium for different trapping states were given.

Detection of one-dimensional migration of single self-interstitial atoms in tungsten using high-voltage electron microscopy

PubMed Central

Amino, T.; Arakawa, K.; Mori, H.

2016-01-01

The dynamic behaviour of atomic-size disarrangements of atoms—point defects (self-interstitial atoms (SIAs) and vacancies)—often governs the macroscopic properties of crystalline materials. However, the dynamics of SIAs have not been fully uncovered because of their rapid migration. Using a combination of high-voltage transmission electron microscopy and exhaustive kinetic Monte Carlo simulations, we determine the dynamics of the rapidly migrating SIAs from the formation process of the nanoscale SIA clusters in tungsten as a typical body-centred cubic (BCC) structure metal under the constant-rate production of both types of point defects with high-energy electron irradiation, which must reflect the dynamics of individual SIAs. We reveal that the migration dimension of SIAs is not three-dimensional (3D) but one-dimensional (1D). This result overturns the long-standing and well-accepted view of SIAs in BCC metals and supports recent results obtained by ab-initio simulations. The SIA dynamics clarified here will be one of the key factors to accurately predict the lifetimes of nuclear fission and fusion materials. PMID:27185352

Displacement damage and predicted non-ionizing energy loss in GaAs

NASA Astrophysics Data System (ADS)

Gao, Fei; Chen, Nanjun; Hernandez-Rivera, Efrain; Huang, Danhong; LeVan, Paul D.

2017-03-01

Large-scale molecular dynamics (MD) simulations, along with bond-order interatomic potentials, have been applied to study the defect production for lattice atom recoil energies from 500 eV to 20 keV in gallium arsenide (GaAs). At low energies, the most surviving defects are single interstitials and vacancies, and only 20% of the interstitial population is contained in clusters. However, a direct-impact amorphization in GaAs occurs with a high degree of probability during the cascade lifetime for Ga PKAs (primary knock-on atoms) with energies larger than 2 keV. The results reveal a non-linear defect production that increases with the PKA energy. The damage density within a cascade core is evaluated, and used to develop a model that describes a new energy partition function. Based on the MD results, we have developed a model to determine the non-ionizing energy loss (NIEL) in GaAs, which can be used to predict the displacement damage degradation induced by space radiation on electronic components. The calculated NIEL predictions are compared with the available data, thus validating the NIEL model developed in this study.

First principles calculations of point defect diffusion in CdS buffer layers: Implications for Cu(In,Ga)(Se,S){sub 2} and Cu{sub 2}ZnSn(Se,S){sub 4}-based thin-film photovoltaics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Varley, J. B.; Lordi, V.; He, X.

2016-01-14

We investigate point defects in CdS buffer layers that may arise from intermixing with Cu(In,Ga)Se{sub 2} (CIGSe) or Cu{sub 2}ZnSn(S,Se){sub 4} (CZTSSe) absorber layers in thin-film photovoltaics (PV). Using hybrid functional calculations, we characterize the migration barriers of Cu, In, Ga, Se, Sn, Zn, Na, and K impurities and assess the activation energies necessary for their diffusion into the bulk of the buffer. We find that Cu, In, and Ga are the most mobile defects in CIGS-derived impurities, with diffusion expected to proceed into the buffer via interstitial-hopping and cadmium vacancy-assisted mechanisms at temperatures ∼400 °C. Cu is predicted to stronglymore » favor migration paths within the basal plane of the wurtzite CdS lattice, which may facilitate defect clustering and ultimately the formation of Cu-rich interfacial phases as observed by energy dispersive x-ray spectroscopic elemental maps in real PV devices. Se, Zn, and Sn defects are found to exhibit much larger activation energies and are not expected to diffuse within the CdS bulk at temperatures compatible with typical PV processing temperatures. Lastly, we find that Na interstitials are expected to exhibit slightly lower activation energies than K interstitials despite having a larger migration barrier. Still, we find both alkali species are expected to diffuse via an interstitially mediated mechanism at slightly higher temperatures than enable In, Ga, and Cu diffusion in the bulk. Our results indicate that processing temperatures in excess of ∼400 °C will lead to more interfacial intermixing with CdS buffer layers in CIGSe devices, and less so for CZTSSe absorbers where only Cu is expected to significantly diffuse into the buffer.« less

Raman spectroscopic studies of defect structures and phase transition in hyper-stoichiometric UO(2+x).

PubMed

He, Heming; Shoesmith, David

2010-07-28

A method to determine the defect structures in hyper-stoichiometric UO(2+x) using a combination of XRD and Raman spectroscopy has been developed. A sequence of phase transitions, from cubic to tetragonal symmetry, occurs with increasing degree of non-stoichiometry. This sequence proceeds from a cubic phase through an intermediate t''-type tetragonal (axial ratio c/a = 1) phase to a final t-type tetragonal (c/a not = 1) phase. Four distinct structural defect regions can be identified in the stoichiometry range, UO(2) to U(3)O(7): (i) a random point defect structure (x (in UO(2+x)) < or = 0.05); (ii) a non-stoichiometry region (0.05 < or = x < or = 0.15) over which point defects are gradually eliminated and replaced by the Willis 2:2:2 cluster; (iii) a mixture of Willis and cuboctahedral clusters (0.15 < or = x < or = 0.23); (iv) the cuboctahedral cluster (x > or = 0.23). The geometry and steric arrangement of these defects is primarily determined by the concentration of the excess-oxygen interstitials.

Electronic structure, stability and magnetic properties of small M1-4(M = Fe, Co, Ni) clusters encapsulated inside a (BN)48 cage

NASA Astrophysics Data System (ADS)

Liang, Wenjuan; Jia, Jianfeng; Lv, Jin; Wu, Haishun

2015-02-01

The geometrical structure and magnetic properties of M1-4(M = Fe, Co and Ni) clusters within a (BN)48 cage were calculated at the BPW91/LanL2DZ level. The small M1-4 clusters generally prefer an off-centered position near the hexagonal rings in the (BN)48 cages. The (BN)48 cages can increase the stability of these small magnetic clusters while protecting the magnetic nature of M and M2 clusters.

Cryptic insertion of 3'FOXO1 into inverted chromosome arm 2q in the presence of two normal chromosome 13s and 13 small interstitial duplications in a patient with alveolar rhabdomyosarcoma.

PubMed

Hackman, Sarah; Calvey, Laura; Bernreuter, Kristen; Mark, Mengya Wang; Starnes, Sarah; Batanian, Jacqueline R

2015-09-01

Alveolar rhabdomyosarcoma (ARMS) is a pediatric soft tissue neoplasm with a characteristic translocation, t(2;13)(q35;q14), which is detected in 70-80% of cases. This well-described translocation produces the gene fusion product PAX3-FOXO1. Cryptic rearrangements of this fusion have never before been reported in ARMS. Here we describe a patient with ARMS that showed, by fluorescence in situ hybridization and G-banded chromosomes, a cryptic insertion of 3'FOXO1 into inverted chromosome 2q. The inversion breakpoints were depicted by array comparative genomic hybridization as two small interstitial duplications, one of which involved the PAX3 gene. In addition, the array comparative genomic hybridization results revealed 1q gain, 16q loss, and 11 more small duplications, with one of them involving the FOXO1 gene. Although the pathogenesis in classic ARMS cases is thought to be driven by the 5'PAX3-3'FOXO1 fusion on derivative chromosome 13, here we report a novel cryptic insertion of 3'FOXO1 resulting in a pathogenic fusion with 5'PAX3 on inverted chromosome 2q. Copyright © 2015 Elsevier Inc. All rights reserved.

Advances in the treatment of rheumatic interstitial lung disease.

PubMed

Vassallo, Robert; Thomas, Charles F

2004-05-01

Interstitial lung disease frequently complicates the rheumatic diseases. The purpose of this review is to outline recent advances and current concepts regarding the management of these interstitial lung diseases. Several histologic lesions cause interstitial lung disease in rheumatic diseases, including nonspecific interstitial pneumonia, usual interstitial pneumonia, organizing pneumonia, lymphocytic interstitial pneumonia, desquamative interstitial pneumonia, and acute interstitial pneumonia. Although the relative frequency of occurrence of these histopathologic lesions is not definitively established, it seems that nonspecific interstitial pneumonia accounts for a large proportion of rheumatic disease-associated interstitial lung diseases. Although usual interstitial pneumonia generally responds poorly to corticosteroid therapy, other forms of interstitial pneumonia are often steroid responsive and have a more favorable long-term prognosis. Pulmonary hypertension is increasingly recognized as a complication of these interstitial lung diseases. Treatment of pulmonary hypertension in these patients provides clinical benefit and may suppress pulmonary inflammation and fibrosis. Lung transplantation is a treatment option for selected patients with severe pulmonary involvement and limited life expectancy. Interstitial lung disease is common in the rheumatic diseases, may be caused by a variety of lesions that respond differently to treatment, and may lead to the development of pulmonary hypertension. Whether the prognosis of interstitial lung disease associated with rheumatic disease is similar to that associated with the idiopathic interstitial pneumonias is not known. Treatment of these interstitial lung diseases should take into account the specific histologic lesion, the activity of the underlying rheumatic disease, and associated pulmonary hypertension, if present. The diagnosis of a rheumatic disease is no longer an absolute contraindication to lung transplantation.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, Chenyang; Niu, Liangliang; Chen, Nanjun

A grand challenge in material science is to understand the correlation between intrinsic properties and defect dynamics. Radiation tolerant materials are in great demand for safe operation and advancement of nuclear and aerospace systems. Unlike traditional approaches that rely on microstructural and nanoscale features to mitigate radiation damage, this study demonstrates enhancement of radiation tolerance with the suppression of void formation by two orders magnitude at elevated temperatures in equiatomic single-phase concentrated solid solution alloys, and more importantly, reveals its controlling mechanism through a detailed analysis of the depth distribution of defect clusters and an atomistic computer simulation. The enhancedmore » swelling resistance is attributed to the tailored interstitial defect cluster motion in the alloys from a long-range one-dimensional mode to a short-range three-dimensional mode, which leads to enhanced point defect recombination. Finally, the results suggest design criteria for next generation radiation tolerant structural alloys.« less

[Cu 32(H) 20{S 2P(O i Pr) 2 } 12 ]: The Largest Number of Hydrides Recorded in a Molecular Nanocluster by Neutron Diffraction

DOE PAGES

Dhayal, Rajendra S.; Liao, Jian-Hong; Kahlal, Samia; ...

2015-04-20

An air- and moisture-stable nanoscale polyhydrido copper cluster [Cu 32(H) 20{S 2P(O i Pr) 2 } 12 ] (1 H) was synthesized and structurally characterized. The molecular structure of 1 H exhibits a hexacapped pseudo-rhombohedral core of 14 Cu atoms sandwiched between two nestlike triangular cupola fragments of (2x9) Cu atoms in an elongated triangular gyrobicupola polyhedron. The discrete Cu 32 cluster is stabilized by 12 dithiophosphate ligands and a record number of 20 hydride ligands, which were found by high-resolution neutron diffraction to exhibit tri-, tetra-, and pentacoordinated hydrides in capping and interstitial modes. We conclude that this resultmore » was further supported by a density functional theory investigation on the simplified model [Cu 32(H) 20(S 2PH 2) 12].« less

Enhancing radiation tolerance by controlling defect mobility and migration pathways in multicomponent single-phase alloys

NASA Astrophysics Data System (ADS)

Lu, Chenyang; Niu, Liangliang; Chen, Nanjun; Jin, Ke; Yang, Taini; Xiu, Pengyuan; Zhang, Yanwen; Gao, Fei; Bei, Hongbin; Shi, Shi; He, Mo-Rigen; Robertson, Ian M.; Weber, William J.; Wang, Lumin

2016-12-01

A grand challenge in material science is to understand the correlation between intrinsic properties and defect dynamics. Radiation tolerant materials are in great demand for safe operation and advancement of nuclear and aerospace systems. Unlike traditional approaches that rely on microstructural and nanoscale features to mitigate radiation damage, this study demonstrates enhancement of radiation tolerance with the suppression of void formation by two orders magnitude at elevated temperatures in equiatomic single-phase concentrated solid solution alloys, and more importantly, reveals its controlling mechanism through a detailed analysis of the depth distribution of defect clusters and an atomistic computer simulation. The enhanced swelling resistance is attributed to the tailored interstitial defect cluster motion in the alloys from a long-range one-dimensional mode to a short-range three-dimensional mode, which leads to enhanced point defect recombination. The results suggest design criteria for next generation radiation tolerant structural alloys.

Bardoxolone Methyl Evaluation in Patients With Pulmonary Hypertension (PH) - LARIAT

ClinicalTrials.gov

2018-06-08

Pulmonary Arterial Hypertension; Pulmonary Hypertension; Interstitial Lung Disease; Idiopathic Interstitial Pneumonia; Idiopathic Pulmonary Fibrosis; Sarcoidosis; Respiratory Bronchiolitis Associated Interstitial Lung Disease; Desquamative Interstitial Pneumonia; Cryptogenic Organizing Pneumonia; Acute Interstitial Pneumonitis; Idiopathic Lymphoid Interstitial Pneumonia; Idiopathic Pleuroparenchymal Fibroelastosis

Data on surface-water, streambed-interstitial water, and bed-sediment quality for selected locations in the small arms impact area of central Fort Gordon, Georgia, September 4-6, 2001

USGS Publications Warehouse

Priest, Sheryln; Stamey, Timothy C.; Lawrence, Stephen J.

2002-01-01

In September 2001, the U.S. Geological Survey, in cooperation with the Environmental and Natural Resources Management Office of the U.S. Army Signal Center and Fort Gordon (U.S. Department of the Army), conducted a chemical assessment of surface water, streambed-interstitial water, and bed sediments within the small arms impact area of Fort Gordon Military Installation. The study was conducted in support of the development of an Integrated Natural Resources Management Plan (INRMP) for Fort Gordon, Georgia. An effective INRMP ensures that natural resources conservation measures and U.S. Army activities on the military base are integrated and consistent with Federal requirements to manage military installations on an ecosystem basis. Filtered water samples were collected from five sites along South Prong Creek and three sites along Marcum Branch Creek for chemical analyses of major ions, nutrients, and selected trace elements. On-site measurements of pH, temperature, specific conductance, and dissolved oxygen were made at the eight sites. Filtered water collected showed varying concentrations in both surface- and streambed-interstitial water. Bed-sediment samples collected from South Prong Creek contain elevated levels of arsenic, barium, beryllium, cadmium, chromium, cobalt, copper, iron, lead, manganese, nickel, selenium, vanadium, and total organic carbon relative to previous concentrations (McConnell and others, 2000). Bed-sediment samples collected from Marcum Branch Creek contain elevated levels of beryllium, copper, lead, manganese, mercury, selenium, and total organic carbon relative to previous concentrations (McConnell and others, 2000).

Layered hydrothermal barite-sulfide mound field, East Diamante Caldera, Mariana volcanic arc

USGS Publications Warehouse

Hein, James R.; de Ronde, Cornel E. J.; Koski, Randolph A.; Ditchburn, Robert G.; Mizell, Kira; Tamura, Yoshihiko; Stern, Robert J.; Conrad, Tracey; Ishizuka, Osamu; Leybourne, Matthew I.

2014-01-01

East Diamante is a submarine volcano in the southern Mariana arc that is host to a complex caldera ~5 × 10 km (elongated ENE-WSW) that is breached along its northern and southwestern sectors. A large field of barite-sulfide mounds was discovered in June 2009 and revisited in July 2010 with the R/V Natsushima, using the ROV Hyper-Dolphin. The mound field occurs on the northeast flank of a cluster of resurgent dacite domes in the central caldera, near an active black smoker vent field. A 40Ar/39Ar age of 20,000 ± 4000 years was obtained from a dacite sample. The mound field is aligned along a series of fractures and extends for more than 180 m east-west and >120 m north-south. Individual mounds are typically 1 to 3 m tall and 0.5 to 2 m wide, with lengths from about 3 to 8 m. The mounds are dominated by barite + sphalerite layers with the margins of each layer composed of barite with disseminated sulfides. Rare, inactive spires and chimneys sit atop some mounds and also occur as clusters away from the mounds. Iron and Mn oxides are currently forming small (<1-m diam, ~0.5-m tall) knolls on the top surface of some of the barite-sulfide mounds and may also drape their flanks. Both diffusely and focused fluids emanate from the small oxide knolls. Radiometric ages of the layered barite-sulfide mounds and chimneys vary from ~3,920 to 3,350 years. One layer, from an outcrop of 10- to 100-cm-thick Cu-rich layers, is notably younger with an age of 2,180 years. The Fe-Mn oxides were <5 years old at the time of collection in 2009.Most mound, chimney, and layered outcrop samples are dominated by barite, silica, and sphalerite; other sulfides, in decreasing order of abundance, are galena, chalcopyrite, and rare pyrite. Anglesite, cerussite, and unidentified Pb oxychloride and Pb phosphate minerals occur as late-stage interstitial phases. The samples contain high Zn (up to 23 wt %), Pb (to 16 wt %), Ag (to 487 ppm), and Au (to 19 ppm) contents. Some layered outcrop samples are dominated by chalcopyrite resulting in ≤4.78 wt % Cu in a bulk sample (28 wt % for a single lens), with a mean of 0.28 wt % for other samples. Other significant metal enrichments are Sb (to 1,320 ppm), Cd (to 1,150 ppm), and Hg (to 55 ppm).The East Diamante mound field has a unique set of characteristics compared to other hydrothermal sites in the Mariana arc and elsewhere. The geochemical differences may predominantly reflect the distribution of fractures and faults and consequently the rock/water ratio, temperature of the fluid in the upper parts of the circulation system, and extensive and prolonged mixing with seawater. The location of mineralization is controlled by fractures. Following resurgent doming within the caldera, mineralization resulted from focused flow along small segments of linear fractures rather than from a point source, typical of hydrothermal chimney fields. Based on the mineral assemblage, the maximum fluid temperatures were ~260°C, near the boiling point for the water depths of the mound field (367–406 m). Lateral fluid flow within the mounds precipitated interstitial sphalerite, silica, and Pb minerals within a network of barite with disseminated sulfides; silica was the final phase to precipitate. The current low-temperature precipitation of Fe and Mn oxides and silica may represent rejuvenation of the system.

Small-scale Conformity of the Virgo Cluster Galaxies

NASA Astrophysics Data System (ADS)

Lee, Hye-Ran; Lee, Joon Hyeop; Jeong, Hyunjin; Park, Byeong-Gon

2016-06-01

We investigate the small-scale conformity in color between bright galaxies and their faint companions in the Virgo Cluster. Cluster member galaxies are spectroscopically determined using the Extended Virgo Cluster Catalog and the Sloan Digital Sky Survey Data Release 12. We find that the luminosity-weighted mean color of faint galaxies depends on the color of adjacent bright galaxy as well as on the cluster-scale environment (gravitational potential index). From this result for the entire area of the Virgo Cluster, it is not distinguishable whether the small-scale conformity is genuine or if it is artificially produced due to cluster-scale variation of galaxy color. To disentangle this degeneracy, we divide the Virgo Cluster area into three sub-areas so that the cluster-scale environmental dependence is minimized: A1 (central), A2 (intermediate), and A3 (outermost). We find conformity in color between bright galaxies and their faint companions (color-color slope significance S ˜ 2.73σ and correlation coefficient {cc}˜ 0.50) in A2, where the cluster-scale environmental dependence is almost negligible. On the other hand, the conformity is not significant or very marginal (S ˜ 1.75σ and {cc}˜ 0.27) in A1. The conformity is not significant either in A3 (S ˜ 1.59σ and {cc}˜ 0.44), but the sample size is too small in this area. These results are consistent with a scenario in which the small-scale conformity in a cluster is a vestige of infallen groups and these groups lose conformity as they come closer to the cluster center.

Interstitial Lung Disease Induced by Osimertinib for Epidermal Growth Factor Receptor (EGFR) T790M-positive Non-small Cell Lung Cancer.

PubMed

Matsumoto, Yoshiya; Kawaguchi, Tomoya; Yamamoto, Norio; Sawa, Kenji; Yoshimoto, Naoki; Suzumura, Tomohiro; Watanabe, Tetsuya; Mitsuoka, Shigeki; Asai, Kazuhisa; Kimura, Tatsuo; Yoshimura, Naruo; Kuwae, Yuko; Hirata, Kazuto

2017-09-01

A 75-year-old man with stage IV lung adenocarcinoma was treated with osimertinib due to disease progression despite having been administered erlotinib. Both an epidermal growth factor receptor (EGFR) L858R mutation on exon 21 and a T790M mutation on exon 20 were detected in a specimen from a recurrent primary tumor. Five weeks after osimertinib initiation, he developed general fatigue and dyspnea. Chest computed tomography scan revealed diffuse ground glass opacities and consolidation on both lungs. An analysis of the bronchoalveolar lavage fluid revealed marked lymphocytosis, and a transbronchial lung biopsy specimen showed a thickened interstitium with fibrosis and prominent lymphocytic infiltration. We diagnosed the patient to have interstitial lung disease induced by osimertinib.

Interstitial Lung Disease Induced by Osimertinib for Epidermal Growth Factor Receptor (EGFR) T790M-positive Non-small Cell Lung Cancer

PubMed Central

Matsumoto, Yoshiya; Kawaguchi, Tomoya; Yamamoto, Norio; Sawa, Kenji; Yoshimoto, Naoki; Suzumura, Tomohiro; Watanabe, Tetsuya; Mitsuoka, Shigeki; Asai, Kazuhisa; Kimura, Tatsuo; Yoshimura, Naruo; Kuwae, Yuko; Hirata, Kazuto

2017-01-01

A 75-year-old man with stage IV lung adenocarcinoma was treated with osimertinib due to disease progression despite having been administered erlotinib. Both an epidermal growth factor receptor (EGFR) L858R mutation on exon 21 and a T790M mutation on exon 20 were detected in a specimen from a recurrent primary tumor. Five weeks after osimertinib initiation, he developed general fatigue and dyspnea. Chest computed tomography scan revealed diffuse ground glass opacities and consolidation on both lungs. An analysis of the bronchoalveolar lavage fluid revealed marked lymphocytosis, and a transbronchial lung biopsy specimen showed a thickened interstitium with fibrosis and prominent lymphocytic infiltration. We diagnosed the patient to have interstitial lung disease induced by osimertinib. PMID:28794368

Interstitial effects of B and Li on the magnetic phase transition and magnetocaloric effects in Gd2In alloy

NASA Astrophysics Data System (ADS)

Yang, Yang; Xie, Yigao; Zhou, Xiaoqian; Zhong, Hui; Jiang, Qingzheng; Ma, Shengcan; Zhong, Zhenchen; Cui, Weibin; Wang, Qiang

2018-05-01

Interstitial effects of B and Li on the phase transition and magnetocaloric effect in Gd2In alloys had been studied. The antiferromagnetic (AFM) - ferromagnetic (FM) phase transition was found to be of first-order nature while ferromagnetic - paramagnetic (PM) phase transition was of second-order nature in B- or Li-doped Gd2In alloys. AFM-FM phase transition temperature was increased while FM-PM phase transition was decreased with more doping concentrations. During AFM-FM phase transition, the slope of temperature-dependent critical field (μ0Hcr) was increased by increased doping amounts. The magnetic entropy changes under small field change were enhanced by B and Li addition, which showed the beneficial effects of B and Li additions.

Visual observations of historical lake trout spawning grounds in western Lake Huron

USGS Publications Warehouse

Nester, Robert T.; Poe, Thomas P.

1987-01-01

Direct underwater video observations were made of the bottom substrates at 12 spawning grounds formerly used by lake trout Salvelinus namaycush in western Lake Huron to evaluate their present suitability for successful reproduction by lake trout. Nine locations examined north of Saginaw Bay in the northwestern end of the lake are thought to provide the best spawning habitat. The substrate at these sites consisted of angular rough cobble and rubble with relatively deep interstitial spaces (a?Y 0.5 m), small amounts of fine sediments, and little or no periphytic growth. Conditions at the three other sampling locations south of Saginaw Bay seemed much less suitable for successful reproduction based on the reduced area of high-quality substrate, shallow interstitial spaces, high infiltration of fine sediments, and greater periphytic growth.

Molecular dynamics simulations of the diffusion and coalescence of helium in tungsten

NASA Astrophysics Data System (ADS)

Zhou, Y. L.; Wang, J.; Hou, Q.; Deng, A. H.

2014-03-01

Molecular dynamics (MD) simulations are performed on the diffusion and coalescence of helium in tungsten. A new method for determining the effective capture radii (ECRs) and the dissociation energies of helium-related defects is proposed in this work. It is observed that the ECR of an interstitial helium atom trapping helium interstitials (denoted as He-Hen, n = 1-3) decreases with increasing temperature, except for He-He2 at T < 400 K. The traditional view that the ECR is approximately equal to the lattice constant, which has been widely used in kinetic Monte Carlo (KMC) and rate theory (RT) models, is only valid in some cases. However, the ECR between an interstitial helium atom and a substitutional helium atom (denoted as He-HeV) always approximates the third nearest-neighbor tetrahedral positions of the HeV. The diffusion coefficients Dn for helium clusters are also investigated. He2 migrates more quickly than a single He atom does at T < 400 K, whereas the diffusion path of He2 changes at higher temperatures. Another counterintuitive observation is that D5 > D3 > D4 at T < 500 K, which can be attributed to the disordered structure of He5. The Arrhenius relation describes the diffusion of Hen well in the temperature range from 300 K to 550 K, whereas the diffusion is not a standard thermally activated process at higher temperatures. Taken together, these results help elucidate the initial stage of helium bubble formation in tungsten as well as the requirements of long-term evolution methods such as KMC or RT models.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ohori, N.P.; Sciurba, F.C.; Owens, G.R.

We report four cases of giant-cell interstitial pneumonia that occurred in association with exposure to hard metals. All patients presented with chronic interstitial lung disease and had open-lung biopsies that revealed marked interstitial fibrosis, cellular interstitial infiltrates, and prominent intraalveolar macrophages as well as giant cells displaying cellular cannibalism. We also review the literature to determine the sensitivity and specificity of giant-cell interstitial pneumonia for hard-metal pneumoconiosis. Although hard-metal pneumoconiosis may take the form of usual interstitial pneumonia, desquamative interstitial pneumonia, and giant-cell interstitial pneumonia, the finding of giant-cell interstitial pneumonia is almost pathognomonic of hard-metal disease and should provokemore » an investigation of occupational exposure. 25 references.« less

Rheumatoid Arthritis-Associated Interstitial Lung Disease and Idiopathic Pulmonary Fibrosis: Shared Mechanistic and Phenotypic Traits Suggest Overlapping Disease Mechanisms.

PubMed

Paulin, Francisco; Doyle, Tracy J; Fletcher, Elaine A; Ascherman, Dana P; Rosas, Ivan O

2015-01-01

The prevalence of clinically evident interstitial lung disease in patients with rheumatoid arthritis is approximately 10%. An additional 33% of undiagnosed patients have interstitial lung abnormalities that can be detected with high-resolution computed tomography. Rheumatoid arthritis-interstitial lung disease patients have three times the risk of death compared to those with rheumatoid arthritis occurring in the absence of interstitial lung disease, and the mortality related to interstitial lung disease is rising. Rheumatoid arthritis-interstitial lung disease is most commonly classified as the usual interstitial pneumonia pattern, overlapping mechanistically and phenotypically with idiopathic pulmonary fibrosis, but can occur in a non-usual interstitial pneumonia pattern, mainly nonspecific interstitial pneumonia. Based on this, we propose two possible pathways to explain the coexistence of rheumatoid arthritis and interstitial lung disease: (i) Rheumatoid arthritis-interstitial lung disease with a non-usual interstitial pneumonia pattern may come about when an immune response against citrullinated peptides taking place in another site (e.g. the joints) subsequently affects the lungs; (ii) Rheumatoid arthritis-interstitial lung disease with a usual interstitial pneumonia pattern may represent a disease process in which idiopathic pulmonary fibrosis-like pathology triggers an immune response against citrullinated proteins that promotes articular disease indicative of rheumatoid arthritis. More studies focused on elucidating the basic mechanisms leading to different sub-phenotypes of rheumatoid arthritis-interstitial lung disease and the overlap with idiopathic pulmonary fibrosis are necessary to improve our understanding of the disease process and to define new therapeutic targets.

Quantifying substructures in Hubble Frontier Field clusters: comparison with ΛCDM simulations

DOE PAGES

Mohammed, Irshad; Saha, Prasenjit; Williams, Liliya L. R.; ...

2016-04-13

The Hubble Frontier Fields (HFF) are six clusters of galaxies, all showing indications of recent mergers, which have recently been observed for lensed images. As such they are the natural laboratories to study the merging history of galaxy clusters. In this work, we explore the 2D power spectrum of the mass distributionmore » $$P_{\\rm M}(k)$$ as a measure of substructure. We compare $$P_{\\rm M}(k)$$ of these clusters (obtained using strong gravitational lensing) to that of $$\\Lambda$$CDM simulated clusters of similar mass. In order to compute lensing $$P_{\\rm M}(k)$$, we produced free-form lensing mass reconstructions of HFF clusters, without any light traces mass (LTM) assumption. Moreover, the inferred power at small scales tends to be larger if (i)~the cluster is at lower redshift, and/or (ii)~there are deeper observations and hence more lensed images. In contrast, lens reconstructions assuming LTM show higher power at small scales even with fewer lensed images; it appears the small scale power in the LTM reconstructions is dominated by light information, rather than the lensing data. The average lensing derived $$P_{\\rm M}(k)$$ shows lower power at small scales as compared to that of simulated clusters at redshift zero, both dark-matter only and hydrodynamical. The possible reasons are: (i)~the available strong lensing data are limited in their effective spatial resolution on the mass distribution, (ii)~HFF clusters have yet to build the small scale power they would have at $$z\\sim 0$$, or (iii)~simulations are somehow overestimating the small scale power.« less

Alkaline degradation studies of anion exchange polymers to enable new membrane designs

NASA Astrophysics Data System (ADS)

Nunez, Sean Andrew

Current performance targets for anion-exchange membrane (AEM) fuel cells call for greater than 95% alkaline stability for 5000 hours at temperatures up to 120 °C. Using this target temperature of 120 °C, an incisive 1H NMR-based alkaline degradation method to identify the degradation products of n-alkyl spacer tetraalkylammonium cations in various AEM polymers and small molecule analogs. Herein, the degradation mechanisms and rates of benzyltrimethylammonium-, n-alkyl interstitial spacer- and n-alkyl terminal pendant-cations are studied on several architectures. These findings demonstrate that benzyltrimethylammonium- and n-alkyl terminal pendant cations are more labile than an n-alkyl interstitial spacer cation and conclude that Hofmann elimination is not the predominant mechanism of alkaline degradation. Additionally, the alkaline stability of an n-alkyl interstitial spacer cation is enhanced when combined with an n-alkyl terminal pendant. Interestingly, at 120 °C, an inverse trend was found in the overall alkaline stability of AEM poly(styrene) and AEM poly(phenylene oxide) samples than was previously shown at 80 °C. Successive small molecule studies suggest that at 120 °C, an anion-induced 1,4-elimination degradation mechanism may be activated on styrenic AEM polymers bearing an acidic alpha-hydrogen. In addition, an ATR-FTIR based method was developed to assess the alkaline stability of solid membranes and any added resistance to degradation that may be due to differential solubilities and phase separation. To increase the stability of anion exchange membranes, Oshima magnesate--halogen exchange was demonstrated as a method for the synthesis of new anion exchange membranes that typically fail in the presence of organolithium or Grignard reagents alone. This new chemistry, applied to non-resinous polymers for the first time, proved effective for the n-akyl interstitial spacer functionalization of poly(phenylene oxide) and poly(styrene- co-ethylene-co-butylene-co-styrene) polymer backbones. The comprehensive methodologies for the assessment of alkaline stability in AEMs as well as the new synthetic methodologies are intended as a guide toward robust AEM synthetic designs that approach current performance standards.

Resolving the problem of galaxy clustering on small scales: any new physics needed?

NASA Astrophysics Data System (ADS)

Kang, X.

2014-02-01

Galaxy clustering sets strong constraints on the physics governing galaxy formation and evolution. However, most current models fail to reproduce the clustering of low-mass galaxies on small scales (r < 1 Mpc h-1). In this paper, we study the galaxy clusterings predicted from a few semi-analytical models. We first compare two Munich versions, Guo et al. and De Lucia & Blaizot. The Guo11 model well reproduces the galaxy stellar mass function, but overpredicts the clustering of low-mass galaxies on small scales. The DLB07 model provides a better fit to the clustering on small scales, but overpredicts the stellar mass function. These seem to be puzzling. The clustering on small scales is dominated by galaxies in the same dark matter halo, and there is slightly more fraction of satellite galaxies residing in massive haloes in the Guo11 model, which is the dominant contribution to the clustering discrepancy between the two models. However, both models still overpredict the clustering at 0.1 < r < 10 Mpc h-1 for low-mass galaxies. This is because both models overpredict the number of satellites by 30 per cent in massive haloes than the data. We show that the Guo11 model could be slightly modified to simultaneously fit the stellar mass function and clusterings, but that cannot be easily achieved in the DLB07 model. The better agreement of DLB07 model with the data actually comes as a coincidence as it predicts too many low-mass central galaxies which are less clustered and thus brings down the total clustering. Finally, we show the predictions from the semi-analytical models of Kang et al. We find that this model can simultaneously fit the stellar mass function and galaxy clustering if the supernova feedback in satellite galaxies is stronger. We conclude that semi-analytical models are now able to solve the small-scales clustering problem, without invoking of any other new physics or changing the dark matter properties, such as the recent favoured warm dark matter.

Diffusion and interactions of interstitials in hard-sphere interstitial solid solutions

NASA Astrophysics Data System (ADS)

van der Meer, Berend; Lathouwers, Emma; Smallenburg, Frank; Filion, Laura

2017-12-01

Using computer simulations, we study the dynamics and interactions of interstitial particles in hard-sphere interstitial solid solutions. We calculate the free-energy barriers associated with their diffusion for a range of size ratios and densities. By applying classical transition state theory to these free-energy barriers, we predict the diffusion coefficients, which we find to be in good agreement with diffusion coefficients as measured using event-driven molecular dynamics simulations. These results highlight that transition state theory can capture the interstitial dynamics in the hard-sphere model system. Additionally, we quantify the interactions between the interstitials. We find that, apart from excluded volume interactions, the interstitial-interstitial interactions are almost ideal in our system. Lastly, we show that the interstitial diffusivity can be inferred from the large-particle fluctuations alone, thus providing an empirical relationship between the large-particle fluctuations and the interstitial diffusivity.

Axial compartmentation of descending and ascending thin limbs of Henle's loops

PubMed Central

Westrick, Kristen Y.; Serack, Bradley; Dantzler, William H.

2013-01-01

In the inner medulla, radial organization of nephrons and blood vessels around collecting duct (CD) clusters leads to two lateral interstitial regions and preferential intersegmental fluid and solute flows. As the descending (DTLs) and ascending thin limbs (ATLs) pass through these regions, their transepithelial fluid and solute flows are influenced by variable transepithelial solute gradients and structure-to-structure interactions. The goal of this study was to quantify structure-to-structure interactions, so as to better understand compartmentation and flows of transepithelial water, NaCl, and urea and generation of the axial osmotic gradient. To accomplish this, we determined lateral distances of AQP1-positive and AQP1-negative DTLs and ATLs from their nearest CDs, so as to gauge interactions with intercluster and intracluster lateral regions and interactions with interstitial nodal spaces (INSs). DTLs express reduced AQP1 and low transepithelial water permeability along their deepest segments. Deep AQP1-null segments, prebend segments, and ATLs lie equally near to CDs. Prebend segments and ATLs abut CDs and INSs throughout much of their descent and ascent, respectively; however, the distal 30% of ATLs of the longest loops lie distant from CDs as they approach the outer medullary boundary and have minimal interaction with INSs. These relationships occur regardless of loop length. Finally, we show that ascending vasa recta separate intercluster AQP1-positive DTLs from descending vasa recta, thereby minimizing dilution of gradients that drive solute secretion. We hypothesize that DTLs and ATLs enter and exit CD clusters in an orchestrated fashion that is important for generation of the corticopapillary solute gradient by minimizing NaCl and urea loss. PMID:23195680

Axial compartmentation of descending and ascending thin limbs of Henle's loops.

PubMed

Westrick, Kristen Y; Serack, Bradley; Dantzler, William H; Pannabecker, Thomas L

2013-02-01

In the inner medulla, radial organization of nephrons and blood vessels around collecting duct (CD) clusters leads to two lateral interstitial regions and preferential intersegmental fluid and solute flows. As the descending (DTLs) and ascending thin limbs (ATLs) pass through these regions, their transepithelial fluid and solute flows are influenced by variable transepithelial solute gradients and structure-to-structure interactions. The goal of this study was to quantify structure-to-structure interactions, so as to better understand compartmentation and flows of transepithelial water, NaCl, and urea and generation of the axial osmotic gradient. To accomplish this, we determined lateral distances of AQP1-positive and AQP1-negative DTLs and ATLs from their nearest CDs, so as to gauge interactions with intercluster and intracluster lateral regions and interactions with interstitial nodal spaces (INSs). DTLs express reduced AQP1 and low transepithelial water permeability along their deepest segments. Deep AQP1-null segments, prebend segments, and ATLs lie equally near to CDs. Prebend segments and ATLs abut CDs and INSs throughout much of their descent and ascent, respectively; however, the distal 30% of ATLs of the longest loops lie distant from CDs as they approach the outer medullary boundary and have minimal interaction with INSs. These relationships occur regardless of loop length. Finally, we show that ascending vasa recta separate intercluster AQP1-positive DTLs from descending vasa recta, thereby minimizing dilution of gradients that drive solute secretion. We hypothesize that DTLs and ATLs enter and exit CD clusters in an orchestrated fashion that is important for generation of the corticopapillary solute gradient by minimizing NaCl and urea loss.

Density functional theory calculations of UO2 oxidation: evolution of UO(2+x), U4O(9-y), U3O7, and U3O8.

PubMed

Andersson, D A; Baldinozzi, G; Desgranges, L; Conradson, D R; Conradson, S D

2013-03-04

Formation of hyperstoichiometric uranium dioxide, UO2+x, derived from the fluorite structure was investigated by means of density functional theory (DFT) calculations. Oxidation was modeled by adding oxygen atoms to UO2 fluorite supercells. For each compound ab initio molecular dynamics simulations were performed to allow the ions to optimize their local geometry. A similar approach was used for studying the reduction of U3O8. In agreement with the experimental phase diagram we identify stable line compounds at the U4O9-y and U3O7 stoichiometries. Although the transition from fluorite to the layered U3O8 structure occurs at U3O7 (UO2.333) or U3O7.333 (UO2.444), our calculated low temperature phase diagram indicates that the fluorite derived compounds are favored up to UO2.5, that is, as long as the charge-compensation for adding oxygen atoms occurs via formation of U(5+) ions, after which the U3O8-y phase becomes more stable. The most stable fluorite UO2+x phases at low temperature (0 K) are based on ordering of split quad-interstitial oxygen clusters. Most existing crystallographic models of U4O9 and U3O7, however, apply the cuboctahedral cluster. To better understand these discrepancies, the new structural models are analyzed in terms of existing neutron diffraction data. DFT calculations were also performed on the experimental cuboctahedral based U4O9-y structure, which enable comparisons between the properties of this phase with the quad-interstitial ones in detail.

Defects in Amorphous Semiconductors: The Case of Amorphous Indium Gallium Zinc Oxide

NASA Astrophysics Data System (ADS)

de Jamblinne de Meux, A.; Pourtois, G.; Genoe, J.; Heremans, P.

2018-05-01

Based on a rational classification of defects in amorphous materials, we propose a simplified model to describe intrinsic defects and hydrogen impurities in amorphous indium gallium zinc oxide (a -IGZO). The proposed approach consists of organizing defects into two categories: point defects, generating structural anomalies such as metal—metal or oxygen—oxygen bonds, and defects emerging from changes in the material stoichiometry, such as vacancies and interstitial atoms. Based on first-principles simulations, it is argued that the defects originating from the second group always act as perfect donors or perfect acceptors. This classification simplifies and rationalizes the nature of defects in amorphous phases. In a -IGZO, the most important point defects are metal—metal bonds (or small metal clusters) and peroxides (O - O single bonds). Electrons are captured by metal—metal bonds and released by the formation of peroxides. The presence of hydrogen can lead to two additional types of defects: metal-hydrogen defects, acting as acceptors, and oxygen-hydrogen defects, acting as donors. The impact of these defects is linked to different instabilities observed in a -IGZO. Specifically, the diffusion of hydrogen and oxygen is connected to positive- and negative-bias stresses, while negative-bias illumination stress originates from the formation of peroxides.

Volume shift and charge instability of simple-metal clusters

NASA Astrophysics Data System (ADS)

Brajczewska, M.; Vieira, A.; Fiolhais, C.; Perdew, J. P.

1996-12-01

Experiment indicates that small clusters show changes (mostly contractions) of the bond lengths with respect to bulk values. We use the stabilized jellium model to study the self-expansion and self-compression of spherical clusters (neutral or ionized) of simple metals. Results from Kohn - Sham density functional theory are presented for small clusters of Al and Na, including negatively-charged ones. We also examine the stability of clusters with respect to charging.

Crohn's disease-associated interstitial lung disease mimicking sarcoidosis: a case report and review of the literature.

PubMed

Thao, Choua; Lagstein, Amir; Allen, Tadashi; Dincer, Huseyin Erhan; Kim, Hyun Joo

2016-10-07

Respiratory involvement in Crohn's disease (CD) is a rare manifestation known to involve the large and small airways, lung parenchyma, and pleura. The clinical presentation is nonspecific, and diagnostic tests can mimic other pulmonary diseases, posing a diagnostic challenge and delay in treatment. We report a case of a 60-year-old female with a history of CD and psoriatic arthritis who presented with dyspnea, fever, and cough with abnormal radiological findings. Diagnostic testing revealed an elevated CD4:CD8 ratio in the bronchoalveolar lavage fluid, and cryoprobe lung biopsy results showed non-necrotizing granulomatous inflammation. We describe here the second reported case of pulmonary involvement mimicking sarcoidosis in Crohn's disease and a review of the literature on the approaches to making a diagnosis of CD-associated interstitial lung disease.

Radiologists' confidence in detecting abnormalities on chest images and their subjective judgments of image quality

NASA Astrophysics Data System (ADS)

King, Jill L.; Gur, David; Rockette, Howard E.; Curtin, Hugh D.; Obuchowski, Nancy A.; Thaete, F. Leland; Britton, Cynthia A.; Metz, Charles E.

1991-07-01

The relationship between subjective judgments of image quality for the performance of specific detection tasks and radiologists' confidence level in arriving at correct diagnoses was investigated in two studies in which 12 readers, using a total of three different display environments, interpreted a series of 300 PA chest images. The modalities used were conventional films, laser-printed films, and high-resolution CRT display of digitized images. For the detection of interstitial disease, nodules, and pneumothoraces, there was no statistically significant correlation (Spearman rho) between subjective ratings of quality and radiologists' confidence in detecting these abnormalities. However, in each study, for all modalities and all readers but one, a small but statistically significant correlation was found between the radiologists' ability to correctly and confidently rule out interstitial disease and their subjective ratings of image quality.

Epigenetic regulation of cardiac fibrosis

PubMed Central

Stratton, Matthew S.; McKinsey, Timothy A.

2016-01-01

Fibrosis is defined as excess deposition of extracellular matrix (ECM), resulting in tissue scarring and organ dysfunction. In the heart, fibrosis may be reparative, replacing areas of myocyte loss with a structural scar following infarction, or reactive, which is triggered in the absence of cell death and involves interstitial ECM deposition in response to long-lasting stress. Interstitial fibrosis can increase the passive stiffness of the myocardium, resulting in impaired relaxation and diastolic dysfunction. Additionally, fibrosis can lead to disruption of electrical conduction in the heart, causing arrhythmias, and can limit myocyte oxygen availability and thus exacerbate myocardial ischemia. Here, we review recent studies that have illustrated key roles for epigenetic events in the control of pro-fibrotic gene expression, and highlight the potential of small molecules that target epigenetic regulators as a means of treating fibrotic cardiac diseases. PMID:26876451

Oxygen-related vacancy-type defects in ion-implanted silicon

NASA Astrophysics Data System (ADS)

Pi, X. D.; Burrows, C. P.; Coleman, P. G.; Gwilliam, R. M.; Sealy, B. J.

2003-10-01

Czochralski silicon samples implanted to a dose of 5 × 1015 cm-2 with 0.5 MeV O and to a dose of 1016 cm-2 with 1 MeV Si, respectively, have been studied by positron annihilation spectroscopy. The evolution of divacancies to vacancy (V)-O complexes is out-competed by V-interstitial (I) recombination at 400 and 500 °C in the Si- and O-implanted samples; the higher oxygen concentration makes the latter temperature higher. The defective region shrinks as the annealing temperature increases as interstitials are injected from the end of the implantation range (Rp). VmOn (m> n) are formed in the shallow region most effectively at 700 °C for both Si and O implantation. VxOy (x< y) are produced near Rp by the annealing. At 800 °C, implanted Si ions diffuse and reduce m and implanted O ions diffuse and increase n in VmOn. All oxygen-related vacancy-type defects appear to begin to dissociate at 950 °C, with the probable formation of oxygen clusters. At 1100 °C, oxygen precipitates appear to form just before Rp in O-implanted silicon.

γH2AX foci on apparently intact mitotic chromosomes: Not signatures of misrejoining events but signals of unresolved DNA damage

PubMed Central

Martín, Marta; Terradas, Mariona; Hernández, Laia; Genescà, Anna

2014-01-01

The presence of γH2AX foci on apparently intact mitotic chromosomes is controversial because they challenge the assumed relationship between γH2AX foci and DNA double-strand breaks (DSBs). In this work, we show that after irradiation during interphase, a variety of γH2AX foci are scored in mitotic cells. Surprisingly, approximately 80% of the γH2AX foci spread over apparently undamaged chromatin at Terminal or Interstitial positions and they can display variable sizes, thus being classified as Small, Medium and Big foci. Chromosome and chromatid breaks that reach mitosis are spotted with Big (60%) and Medium (30%) Terminal γH2AX foci, but very rarely are they signaled with Small γH2AX foci. To evaluate if Interstitial γH2AX foci might be signatures of misrejoining, an mFISH analysis was performed on the same slides. The results show that Interstitial γH2AX foci lying on apparently intact chromatin do not mark sites of misrejoining, and that misrejoined events were never signaled by a γH2AX foci during mitosis. Finally, when analyzing the presence of other DNA-damage response (DDR) factors we found that all γH2AX foci—regardless their coincidence with a visible break—always colocalized with MRE11, but not with 53BP1. This pattern suggests that these γH2AX foci may be hallmarks of both microscopically visible and invisible DNA damage, in which an active, although incomplete or halted DDR is taking place. PMID:25486563

Pemetrexed-related interstitial lung disease reported from post marketing surveillance (malignant pleural mesothelioma/non-small cell lung cancer).

PubMed

Tomii, Keisuke; Kato, Terufumi; Takahashi, Masashi; Noma, Satoshi; Kobashi, Yoichiro; Enatsu, Sotaro; Okubo, Sumiko; Kobayashi, Noriko; Kudoh, Shoji

2017-04-01

Interstitial lung disease (ILD) is important drug related toxicity because it commonly forced to discontinue the treatment. To characterize the prevalence and patterns of pemetrexed induced ILD, an independent ILD advisory board composed of external experts performed reassessment of ILD in two post marketing surveillance (PMS) studies for malignant pleural mesothelioma (MPM) and non-small cell lung cancer (NSCLC). ILD incidences were originally 1.6% and 2.6% in 903 MPM and 683 NSCLC patients in safety analyses, respectively. Based on the reassessment by the board, the incidence was 1.1% MPM and 1.8% NSCLC. Common possible risk factors of ILD in MPM and NSCLC patients were male gender, 60 years or older age, and pre-existing ILD. Asbestosis in MPM, and smoking history in NSCLC are also considered as risk, respectively. In terms of computed tomography (CT) pattern, 7 of 10 cases in MPM patients had acute interstitial pneumonia pattern, which four were fatal. Eight of the 12 NSCLC patients had diffuse grand glass opacity, which all had recovered. Onset of ILD in MPM varied between the first and the fifth courses of pemetrexed treatment, and the latest onset was 48 days after the last administration. For NSCLC, it was between the second and the ninth course, 7 and 56 days after the last administration. The risk of pemetrexed-related ILD is similar level as other anti-cancer drugs under clinical settings. Careful observations continuously during and at least for 2 months after the last administration of pemetrexed are advised. © The Author 2017. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Displacement cascades and defects annealing in tungsten, Part I: Defect database from molecular dynamics simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Setyawan, Wahyu; Nandipati, Giridhar; Roche, Kenneth J.

Molecular dynamics simulations have been used to generate a comprehensive database of surviving defects due to displacement cascades in bulk tungsten. Twenty-one data points of primary knock-on atom (PKA) energies ranging from 100 eV (sub-threshold energy) to 100 keV (~780 × Ed, where Ed = 128 eV is the average displacement threshold energy) have been completed at 300 K, 1025 K and 2050 K. Within this range of PKA energies, two regimes of power-law energy-dependence of the defect production are observed. A distinct power-law exponent characterizes the number of Frenkel pairs produced within each regime. The two regimes intersect atmore » a transition energy which occurs at approximately 250 × Ed. The transition energy also marks the onset of the formation of large self-interstitial atom (SIA) clusters (size 14 or more). The observed defect clustering behavior is asymmetric, with SIA clustering increasing with temperature, while the vacancy clustering decreases. This asymmetry increases with temperature such that at 2050 K (~0.5 Tm) practically no large vacancy clusters are formed, meanwhile large SIA clusters appear in all simulations. The implication of such asymmetry on the long-term defect survival and damage accumulation is discussed. In addition, <100> {110} SIA loops are observed to form directly in the highest energy cascades, while vacancy <100> loops are observed to form at the lowest temperature and highest PKA energies, although the appearance of both the vacancy and SIA loops with Burgers vector of <100> type is relatively rare.« less

Neurokinin B-producing projection neurons in the lateral stripe of the striatum and cell clusters of the accumbens nucleus in the rat.

PubMed

Zhou, Ligang; Furuta, Takahiro; Kaneko, Takeshi

2004-12-06

Neurons producing preprotachykinin B (PPTB), the precursor of neurokinin B, constitute 5% of neurons in the dorsal striatum and project to the substantia innominata (SI) selectively. In the ventral striatum, PPTB-producing neurons are collected mainly in the lateral stripe of the striatum (LSS) and cell clusters of the accumbens nucleus (Acb). In the present study, we first examined the distribution of PPTB-immunoreactive neurons in rat ventral striatum and found that a large part of the PPTB-immunoreactive cell clusters was continuous to the LSS, but a smaller part was not. Thus, we divided the PPTB-immunoreactive cell clusters into the LSS-associated and non-LSS-associated ones. We next investigated the projection targets of the PPTB-producing ventral striatal neurons by combining immunofluorescence labeling and retrograde tracing. After injection of Fluoro-Gold into the basal component of the SI (SIb) and medial part of the interstitial nucleus of posterior limb of the anterior commissure, many PPTB-immunoreactive neurons were retrogradely labeled in the LSS-associated cell clusters and LSS, respectively. When the injection site included the ventral part of the sublenticular component of the SI(SIsl), retrogradely labeled neurons showed PPTB-immunoreactivity frequently in non-LSS-associated cell clusters. Furthermore, these PPTB-immunoreactive projections were confirmed by the double-fluorescence method after anterograde tracer injection into the ventral striatum containing the cell clusters. Since the dorsalmost part of the SIsl is known to receive strong inputs from PPTB-producing dorsal striatal neurons, the present results indicate that PPTB-producing ventral striatal neurons project to basal forebrain target regions in parallel with dorsal striatal neurons without significant convergence. 2004 Wiley-Liss, Inc.

Study of point- and cluster-defects in radiation-damaged silicon

NASA Astrophysics Data System (ADS)

Donegani, Elena M.; Fretwurst, Eckhart; Garutti, Erika; Klanner, Robert; Lindstroem, Gunnar; Pintilie, Ioana; Radu, Roxana; Schwandt, Joern

2018-08-01

Non-ionising energy loss of radiation produces point defects and defect clusters in silicon, which result in a significant degradation of sensor performance. In this contribution results from TSC (Thermally Stimulated Current) defect spectroscopy for silicon pad diodes irradiated by electrons to fluences of a few 1014 cm-2 and energies between 3.5 and 27 MeV for isochronal annealing between 80 and 280∘C, are presented. A method based on SRH (Shockley-Read-Hall) statistics is introduced, which assumes that the ionisation energy of the defects in a cluster depends on the fraction of occupied traps. The difference of ionisation energy of an isolated point defect and a fully occupied cluster, ΔEa, is extracted from the TSC data. For the VOi (vacancy-oxygen interstitial) defect ΔEa = 0 is found, which confirms that it is a point defect, and validates the method for point defects. For clusters made of deep acceptors the ΔEa values for different defects are determined after annealing at 80∘C as a function of electron energy, and for the irradiation with 15 MeV electrons as a function of annealing temperature. For the irradiation with 3.5 MeV electrons the value ΔEa = 0 is found, whereas for the electron energies of 6-27 MeV ΔEa > 0. This agrees with the expected threshold of about 5 MeV for cluster formation by electrons. The ΔEa values determined as a function of annealing temperature show that the annealing rate is different for different defects. A naive diffusion model is used to estimate the temperature dependencies of the diffusion of the defects in the clusters.

Volumetric Optical Frequency Domain Imaging of Pulmonary Pathology With Precise Correlation to Histopathology

PubMed Central

Hariri, Lida P.; Applegate, Matthew B.; Mino-Kenudson, Mari; Mark, Eugene J.; Medoff, Benjamin D.; Luster, Andrew D.; Bouma, Brett E.; Tearney, Guillermo J.

2013-01-01

Background: Lung cancer is the leading cause of cancer-related mortality. Radiology and bronchoscopy techniques do not have the necessary resolution to evaluate lung lesions on the microscopic scale, which is critical for diagnosis. Bronchial biopsy specimens can be limited by sampling error and small size. Optical frequency domain imaging (OFDI) provides volumetric views of tissue microstructure at near-histologic resolution and may be useful for evaluating pulmonary lesions to increase diagnostic accuracy. Bronchoscopic OFDI has been evaluated in vivo, but a lack of correlated histopathology has limited the ability to develop accurate image interpretation criteria. Methods: We performed OFDI through two approaches (airway-centered and parenchymal imaging) in 22 ex vivo lung specimens, using tissue dye to precisely correlate imaging and histology. Results: OFDI of normal airway allowed visualization of epithelium, lamina propria, cartilage, and alveolar attachments. Carcinomas exhibited architectural disarray, loss of normal airway and alveolar structure, and rapid light attenuation. Squamous cell carcinomas showed nested architecture. Atypical glandular formation was appreciated in adenocarcinomas, and uniform trabecular gland formation was seen in salivary gland carcinomas. Mucinous adenocarcinomas showed alveolar wall thickening with intraalveolar mucin. Interstitial fibrosis was visualized as signal-dense tissue, with an interstitial distribution in mild interstitial fibrotic disease and a diffuse subpleural pattern with cystic space formation in usual interstitial pneumonitis. Conclusions: To our knowledge, this study is the first demonstration of volumetric OFDI with precise correlation to histopathology in lung pathology. We anticipate that OFDI may play a role in assessing airway and parenchymal pathology, providing fresh insights into the volumetric features of pulmonary disease. PMID:22459781

Autoantibodies against TIF-1-γ and CADM-140 in Spanish patients with clinically amyopathic dermatomyositis (CADM): clinical significance and diagnostic utility.

PubMed

Cuesta-Mateos, C; Colom-Fernández, B; Portero-Sainz, I; Tejedor, R; García-García, C; Concha-Garzón, M J; De las Heras-Alonso, M E; Martínez, M A; Juarez, C; Muñoz-Calleja, C

2015-03-01

Patients with clinically amyopathic dermatomyositis (CADM) appear to be at risk for developing cancer and interstitial lung diseases, but population data to confirm this hypothesis are limited. Moreover, CADM presents cutaneous and histological findings that may overlap with subacute cutaneous lupus erythematosus (SCLE). To determine the association between myositis-specific autoantibodies, myositis-associated autoantibodies and CADM in Spanish patients. In addition, to study the usefulness of these autoantibodies in the differential diagnosis between CADM and SCLE. Serum samples were tested for myositis-specific autoantibodies and myositis-associated autoantibodies through immunoprecipitation and other standardized methods. Anti-CADM-p140 and anti-p155 antibodies were the only myositis-specific autoantibodies found and were associated with interstitial lung diseases and cancer respectively. No myositis-associated autoantibodies were found in CADM. Moreover, clinical subsets and proportions seemed to differ from Asian cohorts, where anti-CADM-p140 is considered a CADM hallmark antibody and a risk factor for the development of interstitial lung disease. Interestingly, anti-SSA was highly associated with SCLE, whereas no myositis-specific autoantibodies were found in this entity. Association between CADM and myositis-specific autoantibodies and differences between CADM and SCLE were tested on a relatively small cohort of patients. There is an association between cancer-associated myositis and interstitial lung diseases and their hallmark autoantibodies in our cohort. In addition, the combined determination of myositis-specific autoantibodies and SSA autoantibodies may help to accurately discriminate SCLE from CADM. © 2014 European Academy of Dermatology and Venereology.

Nitric oxide activation by distal redox modulation in tetranuclear iron nitrosyl complexes.

PubMed

de Ruiter, Graham; Thompson, Niklas B; Lionetti, Davide; Agapie, Theodor

2015-11-11

A series of tetranuclear iron complexes displaying a site-differentiated metal center was synthesized. Three of the metal centers are coordinated to our previously reported ligand, based on a 1,3,5-triarylbenzene motif with nitrogen and oxygen donors. The fourth (apical) iron center is coordinatively unsaturated and appended to the trinuclear core through three bridging pyrazolates and an interstitial μ4-oxide moiety. Electrochemical studies of complex [LFe3(PhPz)3OFe][OTf]2 revealed three reversible redox events assigned to the Fe(II)4/Fe(II)3Fe(III) (-1.733 V), Fe(II)3Fe(III)/Fe(II)2Fe(III)2 (-0.727 V), and Fe(II)2Fe(III)2/Fe(II)Fe(III)3 (0.018 V) redox couples. Combined Mössbauer and crystallographic studies indicate that the change in oxidation state is exclusively localized at the triiron core, without changing the oxidation state of the apical metal center. This phenomenon is assigned to differences in the coordination environment of the two metal sites and provides a strategy for storing electron and hole equivalents without affecting the oxidation state of the coordinatively unsaturated metal. The presence of a ligand-binding site allowed the effect of redox modulation on nitric oxide activation by an Fe(II) metal center to be studied. Treatment of the clusters with nitric oxide resulted in binding of NO to the apical iron center, generating a {FeNO}(7) moiety. As with the NO-free precursors, the three reversible redox events are localized at the iron centers distal from the NO ligand. Altering the redox state of the triiron core resulted in significant change in the NO stretching frequency, by as much as 100 cm(-1). The increased activation of NO is attributed to structural changes within the clusters, in particular, those related to the interaction of the metal centers with the interstitial atom. The differences in NO activation were further shown to lead to differential reactivity, with NO disproportionation and N2O formation performed by the more electron-rich cluster.

A computer-aided differential diagnosis between UIP and NSIP using automated assessment of the extent and distribution of regional disease patterns at HRCT: comparison with the radiologist's decision

NASA Astrophysics Data System (ADS)

Kim, Namkug; Seo, Joon Beom; Park, Sang Ok; Lee, Youngjoo; Lee, Jeongjin

2009-02-01

To evaluate the accuracy of computer aided differential diagnosis (CADD) between usual interstitial pneumonia (UIP) and nonspecific interstitial pneumonia (NSIP) at HRCT in comparison with that of a radiologist's decision. A computerized classification for six local disease patterns (normal, NL; ground-glass opacity, GGO; reticular opacity, RO; honeycombing, HC; emphysema, EM; and consolidation, CON) using texture/shape analyses and a SVM classifier at HRCT was used for pixel-by-pixel labeling on the whole lung area. The mode filter was applied on the results to reduce noise. Area fraction (AF) of each pattern, directional probabilistic density function (pdf) (dPDF: mean, SD, skewness of pdf /3 directions: superior-inferior, anterior-posterior, central-peripheral), regional cluster distribution pattern (RCDP: number, mean, SD of clusters, mean, SD of centroid of clusters) were automatically evaluated. Spatially normalized left and right lungs were evaluated separately. Disease division index (DDI) on every combination of AFs and asymmetric index (AI) between left and right lung ((left-right)/left) were also evaluated. To assess the accuracy of the system, fifty-four HRCT data sets in patients with pathologically diagnosed UIP (n=26) and NSIP (n=28) were used. For a classification procedure, a CADD-SVM classifier with internal parameter optimization, and sequential forward floating feature selection (SFFS) were employed. The accuracy was assessed by a 5-folding cross validation with 20- times repetition. For comparison, two thoracic radiologists reviewed the whole HRCT images without clinical information and diagnose each case either as UIP or NSIP. The accuracies of radiologists' decision were 0.75 and 0.87, respectively. The accuracies of the CADD system using the features of AF, dPDF, AI of dPDF, RDP, AI of RDP, DDI were 0.70, 0.79, 0.77, 0.80, 0.78, 0.81, respectively. The accuracy of optimized CADD using all features after SFFS was 0.91. We developed the CADD system to differentiate between UIP and NSIP using automated assessment of the extent and distribution of regional disease patterns at HRCT.

Energetics of halogen impurities in thorium dioxide

NASA Astrophysics Data System (ADS)

Kuganathan, Navaratnarajah; Ghosh, Partha S.; Arya, Ashok K.; Dey, Gautam K.; Grimes, Robin W.

2017-11-01

Defect energies for halogen impurity atoms (Cl, Br and I) in thoria are calculated using the generalized gradient approximation and projector augmented plane wave potentials under the framework of density functional theory. The energy to place a halogen atom at a pre-existing lattice site is the incorporation energy. Seven sites are considered: octahedral interstitial, O vacancy, Th vacancy, Th-O di-vacancy cluster (DV) and the three O-Th-O tri-vacancy cluster (NTV) configurations. For point defects and vacancy clusters, neutral and all possible defect charge states up to full formal charge are considered. The most favourable incorporation site for Cl is the singly charged positive oxygen vacancy while for Br and I it is the NTV1 cluster. By considering the energy to form the defect sites, solution energies are generated. These show that in both ThO2-x and ThO2 the most favourable solution equilibrium site for halides is the single positively charged oxygen vacancy (although in ThO2, I demonstrates the same solubility in the NTV1 and DV clusters). Solution energies are much lower in ThO2-x than in ThO2 indicating that stoichiometry is a significant factor in determining solubility. In ThO2, all three halogens are highly insoluble and in ThO2-x Br and I remain insoluble. Although ½Cl2 is soluble in ThO2-x alternative phases such as ZrCl4 exist which are of lower energy.

Clusterization Effects in III-V Nitrides: Nitrogen Vacancies, and Si and Mg Impurities in Aluminum Nitride and Gallium Nitride

NASA Astrophysics Data System (ADS)

Gubanov, V. A.; Pentaleri, E. A.; Boekema, C.; Fong, C. Y.; Klein, B. M.

1997-03-01

We have investigated clusterization of nitrogen vacancies and Si and Mg doping impurities in zinc-blende aluminum nitride (c-AlN) and gallium nitride (c-GaN) by the tight-binding LMTO technique. The calculations used 128-site supercells. Si and Mg atoms replacing ions in both the cation and anion sublattices of the host lattices of the host crystals have been considered. The Mg impurity at cation sites is found to form partially occupied states at the valence-band edge, and may result in p-type conductivity. When Si substitutes for Ga, the impurity band is formed at the conduction-band edge, resulting in n-type conductivity. Si impurities at cation sites, and Mg impurity at anion sites are able to form resonance states in the gap. The influence of impurity clusterization in the host lattice and interstitial sites on electronic properties of c-AlN and c-GaN crystals are modeled. The changes in vacancy- and impurity-state energies, bonding type, localization, density of states at the Fermi level in different host lattices, their dependence on impurity/vacancy concentration are analyzed and compared with the experimental data.

Hydrogen-enhanced clusterization of intrinsic defects and impurities in silicon

NASA Astrophysics Data System (ADS)

Mukashev, B. N.; Abdullin, Kh. A.; Gorelkinskii, Yu. V.; Tamendarov, M. F.; Tokmoldin, S. Zh

2001-01-01

Formation of intrinsic and impurity defect complexes in hydrogenated monocrystalline silicon is studied. Hydrogen was incorporated into samples by different ways: either by proton implantation at 80 and 300 K, or by annealing at 1250°C for 30-60 min in a sealed quartz ampoule containing ∼10 -3 ml of distilled water, or by treatment in hydrogen plasma. Radiation defects were incorporated either during the hydrogen implantation or by additional irradiation with protons or α-particles. The measurements were performed by electron paramagnetic resonance (EPR), deep level transient spectroscopy (DLTS) and infrared absorption (IR) methods. Essential differences of defect formation processes in hydrogenated samples as compared with reference samples were detected. The main reasons responsible for the differences are (i) hydrogen precipitation in a supersaturated solution during thermal treatment; (ii) interaction of hydrogen with defects and impurities and hydrogen-induced formation of defects; (iii) ability of hydrogen to play the role of accelerator of impurities precipitation. These factors result in the formation of vacancy-related, interstitial-related and impurity clusters which are observed only in the presence of hydrogen. The nature of the clusters and possible models of their structure are discussed.

Septicemia in a neonatal calf associated with Chromobacterium violaceum.

PubMed

Ajithdoss, D K; Porter, B F; Calise, D V; Libal, M C; Edwards, J F

2009-01-01

Chromobacterium violaceum infections are highly fatal and rarely reported in domestic animals. This report describes a fatal case of C. violaceum septicemia in a 7-day-old female beef calf. The calf had necrosuppurative omphalophlebitis, necrotizing interstitial pneumonia, necrosuppurative hepatitis and splenitis, anterior uveitis with hypopyon, suppurative polyarthritis, and disseminated hemorrhagic meningitis with multifocal necrotizing encephalitis. Histologically, clusters of gram-negative bacilli were found in many of the lesions. C. violaceum was isolated in high numbers from the lungs, liver, spleen, carpus, and in pure culture from the cerebrospinal fluid. To our knowledge, this is the first case report of chromobacteriosis in a calf.

Interstitial cystitis - resources

MedlinePlus

Resources - interstitial cystitis ... The following organizations are good resources for information on interstitial cystitis : Interstitial Cystitis Association -- www.ichelp.org National Institute of Diabetes and Digestive and Kidney Diseases -- www. ...

Sound controlled rotation of a cluster of small particles on an ultrasonically vibrating metal strip

NASA Astrophysics Data System (ADS)

Zhang, Xueyi; Zheng, Yun; Hu, Junhui

2008-01-01

We show that a vibrating metal strip, mechanically driven by an ultrasonic transducer, can rotate a cluster of small particles around a fixed point, and the diameter of the cluster of small particles can reach a stable value (steady diameter) for a given driving condition. The rotation is very stable when the vibration of the metal strip is appropriate. The revolution speed, its direction, and steady diameter of the particle cluster can be controlled by the operating frequency of the ultrasonic transducer. For shrimp eggs, a revolution speed up to 360rpm can be obtained.

Effects of gap junction inhibition on contraction waves in the murine small intestine in relation to coupled oscillator theory.

PubMed

Parsons, Sean P; Huizinga, Jan D

2015-02-15

Waves of contraction in the small intestine correlate with slow waves generated by the myenteric network of interstitial cells of Cajal. Coupled oscillator theory has been used to explain steplike gradients in the frequency (frequency plateaux) of contraction waves along the length of the small intestine. Inhibition of gap junction coupling between oscillators should lead to predictable effects on these plateaux and the wave dislocation (wave drop) phenomena associated with their boundaries. It is these predictions that we wished to test. We used a novel multicamera diameter-mapping system to measure contraction along 25- to 30-cm lengths of murine small intestine. There were typically two to three plateaux per length of intestine. Dislocations could be limited to the wavefronts immediately about the terminated wave, giving the appearance of a three-pronged fork, i.e., a fork dislocation; additionally, localized decreases in velocity developed across a number of wavefronts, ending with the terminated wave, which could appear as a fork, i.e., slip dislocations. The gap junction inhibitor carbenoxolone increased the number of plateaux and dislocations and decreased contraction wave velocity. In some cases, the usual frequency gradient was reversed, with a plateau at a higher frequency than its proximal neighbor; thus fork dislocations were inverted, and the direction of propagation was reversed. Heptanol had no effect on the frequency or velocity of contractions but did reduce their amplitude. To understand intestinal motor patterns, the pacemaker network of the interstitial cells of Cajal is best evaluated as a system of coupled oscillators. Copyright © 2015 the American Physiological Society.

A systems approach for tumor pharmacokinetics.

PubMed

Thurber, Greg Michael; Weissleder, Ralph

2011-01-01

Recent advances in genome inspired target discovery, small molecule screens, development of biological and nanotechnology have led to the introduction of a myriad of new differently sized agents into the clinic. The differences in small and large molecule delivery are becoming increasingly important in combination therapies as well as the use of drugs that modify the physiology of tumors such as anti-angiogenic treatment. The complexity of targeting has led to the development of mathematical models to facilitate understanding, but unfortunately, these studies are often only applicable to a particular molecule, making pharmacokinetic comparisons difficult. Here we develop and describe a framework for categorizing primary pharmacokinetics of drugs in tumors. For modeling purposes, we define drugs not by their mechanism of action but rather their rate-limiting step of delivery. Our simulations account for variations in perfusion, vascularization, interstitial transport, and non-linear local binding and metabolism. Based on a comparison of the fundamental rates determining uptake, drugs were classified into four categories depending on whether uptake is limited by blood flow, extravasation, interstitial diffusion, or local binding and metabolism. Simulations comparing small molecule versus macromolecular drugs show a sharp difference in distribution, which has implications for multi-drug therapies. The tissue-level distribution differs widely in tumors for small molecules versus macromolecular biologic drugs, and this should be considered in the design of agents and treatments. An example using antibodies in mouse xenografts illustrates the different in vivo behavior. This type of transport analysis can be used to aid in model development, experimental data analysis, and imaging and therapeutic agent design.

Theoretical research program to study transition metal trimers and embedded clusters

NASA Technical Reports Server (NTRS)

Walch, S. P.

1984-01-01

Small transition metal clusters were studied at a high level of approximation, including all the valence electrons in the calculation and extensive electron correlation, in order to understand the electronic structure of these small metal clusters. By comparison of dimers, trimers, and possibly higher clusters, the information obtained was used to provide insights into the electronic structure of bulk transition metals. Small metal clusters are currently of considerable experimental interest and some information is becomming available both from matrix electron spin resonance studies and from gas phase spectroscopy. Collaboration between theorists and experimentalists is thus expected to be especially profitable at this time since there is some experimental information which can serve to guide the theoretical work.

Blind Leak Detection for Closed Systems

NASA Technical Reports Server (NTRS)

Oelgoetz, Peter; Johnson, Ricky; Todd, Douglas; Russell, Samuel; Walker, James

2003-01-01

The current inspection technique for locating interstitial leaking in the Space Shuttle Main Engine nozzles is the application of a liquid leak check solution in the openings where the interstitials space between the tubing and the structural jacket vent out the aft end of the nozzle, while its cooling tubes are pressurized to 25 psig with Helium. When a leak is found, it is classified, and if the leak is severe enough the suspect tube is cut open so that a boroscope can be inserted to find the leak point. Since the boroscope can only cover a finite tube length and since it is impossible to identify which tube (to the right or left of the identified interstitial) is leaking, many extra and undesired repairs have been made to fix just one leak. In certain instances when the interstitials are interlinked by poor braze bonding, many interstitials will show indications of leaking from a single source. What is desired is a technique that can identify the leak source so that a single repair can be performed. Dr, Samuel Russell and James Walker, both with NASA/MSFC have developed a thermographic inspection system that addresses a single repair approach. They have teamed with Boeing/Rocketdyne to repackage the inspection processes to be suitable to address full scale Shuttle development and flight hardware and implement the process at NASA centers. The methods and results presented address the thermographic identification of interstitial leaks in the Space Shuttle Main Engine nozzles. A highly sensitive digital infrared camera (capable of detecting a delta temperature difference of 0.025 C) is used to record the cooling effects associated with a leak source, such as a crack or pinhole, hidden within the nozzle wall by observing the inner hot wall surface as the nozzle is pressurized, These images are enhanced by digitally subtracting a thermal reference image taken before pressurization. The method provides a non-intrusive way of locating the tube that is leaking and the exact leak source position to within a very small axial distance. Many of the factors that influence the inspectability of the nozzle are addressed; including pressure rate, peak pressure, gas type, ambient temperature and surface preparation. Other applications for this thermographic inspection system are the Reinforced-Carbon-Carbon (RCC) leading edge of the Space Shuttle orbiter and braze joint integrity.

Recommendations of the Spanish brachytherapy group (GEB) of Spanish Society of Radiation Oncology (SEOR) and the Spanish Society of Medical Physics (SEFM) for high-dose rate (HDR) non melanoma skin cancer brachytherapy.

PubMed

Rodríguez, S; Arenas, M; Gutierrez, C; Richart, J; Perez-Calatayud, J; Celada, F; Santos, M; Rovirosa, A

2018-04-01

Clinical indications of brachytherapy in non-melanoma skin cancers, description of applicators and dosimetry recommendations are described based on the literature review, clinical practice and experience of Spanish Group of Brachytherapy and Spanish Society of Medical Physics reported in the XIV Annual Consensus Meeting on Non Melanoma Skin Cancer Brachytherapy held in Benidorm, Alicante (Spain) on October 21st, 2016. All the recommendations for which consensus was achieved are highlighted in blue. Regular and small surfaces may be treated with Leipzig, Valencia, flap applicators or electronic brachytherapy (EBT). For irregular surfaces, customized molds or interstitial implants should be employed. The dose is prescribed at a maximum depth of 3-4 mm of the clinical target volume/planning target volume (CTV/PTV) in all cases except in flaps or molds in which 5 mm is appropriate. Interstitial brachytherapy should be used for CTV/PTV >5 mm. Different total doses and fraction sizes are used with very similar clinical and toxicity results. Hypofractionation is very useful twice or 3 times a week, being comfortable for patients and practical for Radiotherapy Departments. In interstitial brachytherapy 2 fractions twice a day are applied.

Icotinib combined with rapamycin in a renal transplant recipient with epidermal growth factor receptor-mutated non-small cell lung cancer: A case report.

PubMed

Zhao, Qiong; Wang, Yina; Tang, Yemin; Peng, Ling

2014-01-01

As kidney transplant recipients are at increased risk of developing cancer, regular monitoring should be undertaken to monitor the balance between immunosuppression and graft function and to identify malignancy. The present study reports the outcome of the treatment of adenocarcinoma of the lung (T1aN0M1a, stage IV) using the molecular-targeted therapy, icotinib, in a 66-year-old male renal transplant patient receiving rapamycin and prednisolone as ongoing renal immunosuppressive therapy. An initial partial response to icotinib was achieved, and graft function remained good. However, the patient subsequently developed interstitial pneumonitis. The plasma concentrations of rapamycin and icotinib were within the normal ranges, which excluded the possibility of a pharmacokinetic drug interaction and indicated that the interstitial pneumonitis was likely to be associated with the side-effects of icotinib. Drug therapy was discontinued and the patient underwent a segmentectomy. Tacrolimus was administered for ongoing renal graft immunosuppression. To the best of our knowledge, this is the first report of the concomitant administration of icotinib and rapamycin in post-transplant de novo lung cancer. It is also the first report of interstitial pneumonitis associated with icotinib in a post-transplant patient.

Taenia crassiceps: infections of male mice lead to severe disruption of seminiferous tubule cells and increased apoptosis.

PubMed

Zepeda, Nadia; Copitin, Natalia; Solano, Sandra; González, Maricarmen; Fernández, Ana M; Tato, Patricia; Molinari, José L

2011-01-01

This research was carried out to study the effects of infection with Taenia crassiceps cysticerci on the seminiferous epithelium histoarchitecture in the testes of male mice. Our results showed a severe disruption of the histoarchitecture of the testis epithelium in infected mice. In these animals, a significant infiltration of macrophages within seminiferous tubules was observed (P < 0.001). Generalized apoptosis of germ cells within the seminiferous tubules was observed, as assessed by TUNEL assay and apoptotic nuclei were quantified. The total number of fluorescent objects (DNA) (including clusters, singles, and objects in clusters) was significantly higher in the infected cells than in the control group (P = 0.0286). Observation of the interstitial tissue showed disorder and deterioration of many Leydig cells of infected mice, as well as intense vacuolization and destruction of their inter-cellular junctions. Several ultrastructural abnormalities were observed through electron microscopy as well. The observed pathology could lead to a state of infertility. Copyright © 2010 Elsevier Inc. All rights reserved.

Icosahedral and decagonal quasicrystals of intermetallic compounds are multiple twins of cubic or orthorhombic crystals composed of very large atomic complexes with icosahedral point-group symmetry in cubic close packing or body-centered packing: Structure of decagonal Al6Pd

PubMed Central

Pauling, Linus

1989-01-01

A doubly icosahedral complex involves roughly spherical clusters of atoms with icosahedral point-group symmetry, which are themselves, in parallel orientation, icosahedrally packed. These complexes may form cubic crystallites; three structures of this sort have been identified. Analysis of electron diffraction photographs of the decagonal quasicrystal Al6Pd has led to its description as involving pentagonal twinning of an orthorhombic crystal with a = 51.6 Å, b = 37.6 Å, and c = 33.24 Å, with about 4202 atoms in the unit, comprising two 1980-atom doubly icosahedral complexes, each involving icosahedral packing of 45 44-atom icosahedral complexes (at 0 0 0 and 1/2 1/2 1/2) and 242 interstitial atoms. The complexes and clusters are oriented with one of their fivefold axes in the c-axis direction. Images PMID:16594092

Icosahedral and decagonal quasicrystals of intermetallic compounds are multiple twins of cubic or orthorhombic crystals composed of very large atomic complexes with icosahedral point-group symmetry in cubic close packing or body-centered packing: Structure of decagonal Al(6)Pd.

PubMed

Pauling, L

1989-12-01

A doubly icosahedral complex involves roughly spherical clusters of atoms with icosahedral point-group symmetry, which are themselves, in parallel orientation, icosahedrally packed. These complexes may form cubic crystallites; three structures of this sort have been identified. Analysis of electron diffraction photographs of the decagonal quasicrystal Al(6)Pd has led to its description as involving pentagonal twinning of an orthorhombic crystal with a = 51.6 A, b = 37.6 A, and c = 33.24 A, with about 4202 atoms in the unit, comprising two 1980-atom doubly icosahedral complexes, each involving icosahedral packing of 45 44-atom icosahedral complexes (at 0 0 0 and 1/2 1/2 1/2) and 242 interstitial atoms. The complexes and clusters are oriented with one of their fivefold axes in the c-axis direction.

Enhancing radiation tolerance by controlling defect mobility and migration pathways in multicomponent single-phase alloys

DOE PAGES

Lu, Chenyang; Niu, Liangliang; Chen, Nanjun; ...

2016-12-15

A grand challenge in material science is to understand the correlation between intrinsic properties and defect dynamics. Radiation tolerant materials are in great demand for safe operation and advancement of nuclear and aerospace systems. Unlike traditional approaches that rely on microstructural and nanoscale features to mitigate radiation damage, this study demonstrates enhancement of radiation tolerance with the suppression of void formation by two orders magnitude at elevated temperatures in equiatomic single-phase concentrated solid solution alloys, and more importantly, reveals its controlling mechanism through a detailed analysis of the depth distribution of defect clusters and an atomistic computer simulation. The enhancedmore » swelling resistance is attributed to the tailored interstitial defect cluster motion in the alloys from a long-range one-dimensional mode to a short-range three-dimensional mode, which leads to enhanced point defect recombination. Finally, the results suggest design criteria for next generation radiation tolerant structural alloys.« less

Adsorption behavior of Fe atoms on a naphthalocyanine monolayer on Ag(111) surface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yan, Ling -Hao; Wu, Rong -Ting; Bao, De -Liang

2015-05-29

Adsorption behavior of Fe atoms on a metal-free naphthalocyanine (H 2Nc) monolayer on Ag(111) surface at room temperature has been investigated using scanning tunneling microscopy combined with density functional theory (DFT) based calculations. We found that the Fe atoms adsorbed at the centers of H 2Nc molecules and formed Fe-H 2Nc complexes at low coverage. DFT calculations show that the configuration of Fe at the center of a molecule is the most stable site, in good agreement with the experimental observations. After an Fe-H 2Nc complex monolayer was formed, the extra Fe atoms self-assembled to Fe clusters of uniform sizemore » and adsorbed dispersively at the interstitial positions of Fe-H 2Nc complex monolayer. Furthermore, the H 2Nc monolayer grown on Ag(111) could be a good template to grow dispersed magnetic metal atoms and clusters at room temperature for further investigation of their magnetism-related properties.« less

Power and money in cluster randomized trials: when is it worth measuring a covariate?

PubMed

Moerbeek, Mirjam

2006-08-15

The power to detect a treatment effect in cluster randomized trials can be increased by increasing the number of clusters. An alternative is to include covariates into the regression model that relates treatment condition to outcome. In this paper, formulae are derived in order to evaluate both strategies on basis of their costs. It is shown that the strategy that uses covariates is more cost-efficient in detecting a treatment effect when the costs to measure these covariates are small and the correlation between the covariates and outcome is sufficiently large. The minimum required correlation depends on the cluster size, and the costs to recruit a cluster and to measure the covariate, relative to the costs to recruit a person. Measuring a covariate that varies at the person level only is recommended when cluster sizes are small and the costs to recruit and measure a cluster are large. Measuring a cluster level covariate is recommended when cluster sizes are large and the costs to recruit and measure a cluster are small. An illustrative example shows the use of the formulae in a practical setting. Copyright 2006 John Wiley & Sons, Ltd.

WFPC2 Observations of Star Clusters in the Magellanic Clouds. Report 2; The Oldest Star Clusters in the Small Magellanic Cloud

NASA Technical Reports Server (NTRS)

Mighell, Kenneth J.; Sarajedini, Ata; French, Rica S.

1998-01-01

We present our analysis of archival Hubble Space Telescope Wide Field Planetary Camera 2 (WFPC2) observations in F45OW ( approximately B) and F555W (approximately V) of the intermediate-age populous star clusters NGC 121, NGC 339, NGC 361, NGC 416, and Kron 3 in the Small Magellanic Cloud. We use published photometry of two other SMC populous star clusters, Lindsay 1 and Lindsay 113, to investigate the age sequence of these seven populous star clusters in order to improve our understanding of the formation chronology of the SMC. We analyzed the V vs B-V and M(sub V) vs (B-V)(sub 0) color-magnitude diagrams of these populous Small Magellanic Cloud star clusters using a variety of techniques and determined their ages, metallicities, and reddenings. These new data enable us to improve the age-metallicity relation of star clusters in the Small Magellanic Cloud. In particular, we find that a closed-box continuous star-formation model does not reproduce the age-metallicity relation adequately. However, a theoretical model punctuated by bursts of star formation is in better agreement with the observational data presented herein.

Atomistic Simulation of Interstitial Dislocation Loop Evolution under Applied Stresses in BCC Iron

DOE Office of Scientific and Technical Information (OSTI.GOV)

Long, Xue Hao; Wang, Dong; Setyawan, Wahyu

Evolution of an interstitial 1/2⟨111⟩ dislocation loop under tensile, shear, and torsion stresses is studied with molecular statics method. Under a tensile stress, the dependence of ultimate tensile strength on size of loop is calculated. The formation of small shear loops around the initial prismatic loop is confirmed as an intermediate state to form the final dislocation network. Under a shear stress, the rotation of a loop is observed not only by a change of the habit plane but also through a transformation between a shear and a prismatic loop. Under torsion, a perfect BCC crystal may undergo a BCCmore » to FCC or BCC to HCP transformation. The present work indicates that a 1/2⟨111⟩ loop can delay these transformations, resulting in the formation of micro-crack on the surface.« less

A Rate-Theory-Phase-Field Model of Irradiation-Induced Recrystallization in UMo Nuclear Fuels

NASA Astrophysics Data System (ADS)

Hu, Shenyang; Joshi, Vineet; Lavender, Curt A.

2017-12-01

In this work, we developed a recrystallization model to study the effect of microstructures and radiation conditions on recrystallization kinetics in UMo fuels. The model integrates the rate theory of intragranular gas bubble and interstitial loop evolutions and a phase-field model of recrystallization zone evolution. A first passage method is employed to describe one-dimensional diffusion of interstitials with a diffusivity value several orders of magnitude larger than that of fission gas xenons. With the model, the effect of grain sizes on recrystallization kinetics is simulated. The results show that (1) recrystallization in large grains starts earlier than that in small grains, (2) the recrystallization kinetics (recrystallization volume fraction) decrease as the grain size increases, (3) the predicted recrystallization kinetics are consistent with the experimental results, and (4) the recrystallization kinetics can be described by the modified Avrami equation, but the parameters of the Avrami equation strongly depend on the grain size.

Lack of small-scale clustering in 21-cm intensity maps crossed with 2dF galaxy densities at z ~ 0.08

NASA Astrophysics Data System (ADS)

Anderson, Christopher; Luciw, Nicholas; Li, Yi-Chao; Kuo, Cheng-Yu; Yadav, Jaswant; Masui, Kiyoshi; Chang, Tzu-Ching; Chen, Xuelei; Oppermann, Niels; Pen, Ue-Li; Timbie, Peter T.

2017-06-01

I report results from 21-cm intensity maps acquired from the Parkes radio telescope and cross-correlated with galaxy maps from the 2dF galaxy survey. The data span the redshift range 0.057

Method and apparatus for detecting and/or imaging clusters of small scattering centers in the body

DOEpatents

Perez-Mendez, V.; Sommer, F.G.

1982-07-13

An ultrasonic method and apparatus are provided for detecting and imaging clusters of small scattering centers in the breast wherein periodic pulses are applied to an ultrasound emitting transducer and projected into the body, thereafter being received by at least one receiving transducer positioned to receive scattering from the scattering center clusters. The signals are processed to provide an image showing cluster extent and location. 6 figs.

Method and apparatus for detecting and/or imaging clusters of small scattering centers in the body

DOEpatents

Perez-Mendez, Victor; Sommer, Frank G.

1982-01-01

An ultrasonic method and apparatus are provided for detecting and imaging clusters of small scattering centers in the breast wherein periodic pulses are applied to an ultrasound emitting transducer and projected into the body, thereafter being received by at least one receiving transducer positioned to receive scattering from the scattering center clusters. The signals are processed to provide an image showing cluster extent and location.

Hot and solid gallium clusters: too small to melt.

PubMed

Breaux, Gary A; Benirschke, Robert C; Sugai, Toshiki; Kinnear, Brian S; Jarrold, Martin F

2003-11-21

A novel multicollision induced dissociation scheme is employed to determine the energy content for mass-selected gallium cluster ions as a function of their temperature. Measurements were performed for Ga(+)(n) (n=17 39, and 40) over a 90-720 K temperature range. For Ga+39 and Ga+40 a broad maximum in the heat capacity-a signature of a melting transition for a small cluster-occurs at around 550 K. Thus small gallium clusters melt at substantially above the 302.9 K melting point of bulk gallium, in conflict with expectations that they will remain liquid to below 150 K. No melting transition is observed for Ga+17.

The Interstitial Duplication 15q11.2-q13 Syndrome Includes Autism, Mild Facial Anomalies and a Characteristic EEG Signature

PubMed Central

Urraca, Nora; Cleary, Julie; Brewer, Victoria; Pivnick, Eniko K; McVicar, Kathryn; Thibert, Ronald L; Schanen, N Carolyn; Esmer, Carmen; Lamport, Dustin; Reiter, Lawrence T

2013-01-01

Chromosomal copy number variants (CNV) are the most common genetic lesion found in autism. Many autism-associated CNVs are duplications of chromosome 15q. Although most cases of interstitial (int) dup(15) that present clinically are de novo and maternally derived or inherited, both pathogenic and unaffected paternal duplications of 15q have been identified. We performed a phenotype/genotype analysis of individuals with interstitial 15q duplications to broaden our understanding of the 15q syndrome and investigate the contribution of 15q duplication to increased autism risk. All subjects were recruited solely on the basis of interstitial duplication 15q11.2-q13 status. Comparative array genome hybridization was used to determine the duplication size and boundaries while the methylation status of the maternally methylated small nuclear ribonucleoprotein polypeptide N gene was used to determine the parent of origin of the duplication. We determined the duplication size and parental origin for 14 int dup(15) subjects: 10 maternal and 4 paternal cases. The majority of int dup(15) cases recruited were maternal in origin, most likely due to our finding that maternal duplication was coincident with autism spectrum disorder. The size of the duplication did not correlate with the severity of the phenotype as established by Autism Diagnostic Observation Scale calibrated severity score. We identified phenotypes not comprehensively described before in this cohort including mild facial dysmorphism, sleep problems and an unusual electroencephalogram variant. Our results are consistent with the hypothesis that the maternally expressed ubiquitin protein ligase E3A gene is primarily responsible for the autism phenotype in int dup(15) since all maternal cases tested presented on the autism spectrum. PMID:23495136

Patterns of interstitial lung disease during everolimus treatment in patients with metastatic renal cell carcinoma.

PubMed

Mizuno, Ryuichi; Asano, Koichiro; Mikami, Shuji; Nagata, Hirohiko; Kaneko, Gou; Oya, Mototsugu

2012-05-01

To elucidate the patterns of interstitial lung disease during everolimus treatment in patients with metastatic renal cell carcinoma, we reviewed seven cases of everolimus-induced interstitial lung disease. Seven patients with metastatic renal cell carcinoma, which continued to progress despite treatment with sunitinib or sorafenib, developed interstitial lung disease after treatment with everolimus. Chest X-ray demonstrated diffuse infiltrates in lung fields, and chest computed tomography showed bilateral reticular and ground-glass opacities. Serum levels of lactate dehydrogenase (7/7), C-reactive protein (6/7), pulmonary surfactant associated protein D (1/7) and Krebs von den Lungen 6 (5/7) were elevated. The bronchoalveolar lavage fluid obtained from four patients with Grade 3 interstitial lung disease showed lymphocytosis. The transbronchial lung biopsy specimens showed interstitial lymphocytic infiltration and septal thickening of alveolar walls. In two cases with mild interstitial lung disease, the everolimus therapy was successfully continued. In four cases with Grade 3 interstitial lung disease, the drug was discontinued and steroid therapy was initiated. Pulmonary symptoms and radiological abnormalities resolved within 2 months. Serum Krebs von den Lungen 6 was elevated compared with baseline in all cases with interstitial lung disease. Some patients who developed mild interstitial lung disease during everolimus treatment could continue to receive the treatment. Even when severe interstitial lung disease developed, withdrawal of the drug and short-term use of high-dose steroids resulted in rapid recovery. Prompt recognition of interstitial lung disease exacerbation as well as exclusion of progressive disease or infection is of primary importance.

Changes in the interstitial fluid and the muscle water in rabbits in hemorrhagic shock.

PubMed Central

Wolcott, M W; Malinin, T I; Wu, N M

1976-01-01

Dynamics and changes in the biochemical composition in the interstitial fluid and the muscle water were studied in hemorrhagic shock. The interstitial fluid was collected from implanted perforated capsules. Muscle biopsies were examined with regard to their water content by the steady state magnetic nuclear resonance spectroscopy. The consistent and what appears to be the most significant changes were the fall in the interstitial fluid pressures, the quantitative reduction of muscle water, a sharp fall in the blood and interstitial blood pH, the moderate hyperkalemia and lack of change in blood an interstitial fluid sodium, and the rise in blood glucose levels not accompanied by a rise in the interstitial fluid glucose levels. PMID:11754

Modulation of Pacemaker Potentials in Murine Small Intestinal Interstitial Cells of Cajal by Gamisoyo-San, a Traditional Chinese Herbal Medicine.

PubMed

Kim, Doeun; Kim, Jung Nam; Nam, Joo Hyun; Lee, Jong Rok; Kim, Sang Chan; Kim, Byung Joo

2018-04-19

The Gamisoyo-san (GSS) has been used for -improving the gastrointestinal (GI) symptoms. The purpose of this study was to investigate the effects of GSS, a traditional Chinese herbal medicine, on the pacemaker potentials of mouse small intestinal interstitial cells of Cajal (ICCs). ICCs from the small intestines were dissociated and cultured. Whole-cell patch-clamp configuration was used to record pacemaker potentials and membrane currents. GSS depolarized ICC pacemaker potentials in a dose-dependent manner. Pretreatment with 4-diphenylacetoxypiperidinium iodide completely inhibited GSS-induced pacemaker potential depolarizations. Intracellular GDP-β-S inhibited GSS-induced effects, and in the presence of U-73122, GSS-induced effects were inhibited. Also, GSS in the presence of a Ca2+-free solution or thapsigargin did not depolarize pacemaker potentials. However, in the presence of calphostin C, GSS slightly depolarized pacemaker potentials. Furthermore, GSS inhibited both transient receptor potential melastatin7 and Ca2+-activated Cl- channel (anoctamin1) currents. GSS depolarized pacemaker potentials of ICCs via G protein and muscarinic M3 receptor signaling pathways and through internal or external Ca2+-, phospholipase C-, and protein kinase C-dependent and transient receptor potential melastatin 7-, and anoctamin 1-independent pathways. The study shows that GSS may regulate GI tract motility, suggesting that GSS could be a basis for developing novel prokinetic agents for treating GI motility dysfunctions. © 2018 S. Karger AG, Basel.

Magic Numbers in Small Iron Clusters: A First-Principles Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Eunja; Mohrland, Andrew B.; Weck, Philippe F.

2014-10-03

We perform ab initio spin-polarized density functional calculations of Fen aggregates with n ≤ 17 atoms to reveal the origin of the observed magic numbers, which indicate particularly high stability of clusters with 7, 13 and 15 atoms. Our results clarify the controversy regarding the ground state geometry of clusters such as Fe5and indicate that magnetism plays an important role in determining the stability and magic numbers in small iron clusters.

[Airway-centered interstitial fibrosis related to exposure to fumes from cleaning products].

PubMed

Serrano, Mario; Molina-Molina, María; Ramírez, José; Sánchez, Marcelo; Xaubet, Antoni

2006-10-01

Airway-centered interstitial fibrosis is a little known clinical entity that has only recently been described in the literature. Its pathology is characterized by bronchial fibrosis and localized interstitial pulmonary fibrosis around the airways. The disease has been associated with inhalation of a variety of substances, environmental or occupational, organic or inorganic. Clinical signs, radiographic manifestations, and lung function in patients with airway-centered interstitial fibrosis are similar to those of patients with idiopathic interstitial pneumonia. We describe a case of airway-centered interstitial fibrosis related to exposure to fumes from cleaning products.

On the Clustering of Europa's Small Craters

NASA Technical Reports Server (NTRS)

Bierhaus, E. B.; Chapman, C. R.; Merline, W. J.

2001-01-01

We analyze the spatial distribution of Europa's small craters and find that many are too tightly clustered to result from random, primary impacts. Additional information is contained in the original extended abstract.

Interstitial space and collagen alterations of the developing rat diaphragm

NASA Technical Reports Server (NTRS)

Gosselin, L. E.; Martinez, D. A.; Vailas, A. C.; Sieck, G. C.

1993-01-01

The effect of growth on the relative interstitial space [%total cross-sectional area (CSA)] and collagen content of the rat diaphragm muscle was examined at postnatal ages of 0, 7, 14, and 21 days as well as in adult males. The proportion of interstitial space relative to total muscle CSA was determined by computerized image analysis of lectin-stained cross sections of diaphragm muscle. To assess collagen content and extent of collagen maturation (i.e., cross-linking), high-pressure liquid chromatography analysis was used to measure hydroxyproline concentration and the nonreducible collagen cross-link hydroxylysylpyridinoline (HP), respectively. At birth, interstitial space accounted for approximately 47% of total diaphragm muscle CSA. During postnatal growth, the relative contribution of interstitial space decreased such that by adulthood the interstitial space accounted for approximately 18% of total muscle CSA. The change in relative interstitial space occurred without a concomitant change in hydroxyproline concentration. However, the concentration of HP markedly increased with age such that the adult diaphragm contained approximately 17 times more HP than at birth. These results indicate that during development the relative CSA occupied by interstitial space decreases as muscle fiber size increases. However, the reduction in relative interstitial space is not associated with a change in collagen concentration. Thus collagen density in the interstitial space may increase with age. It is possible that the observed changes in relative interstitial space and collagen influence the passive length-force properties of the diaphragm.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ben-Naim, Eli; Krapivsky, Paul

Here we generalize the ordinary aggregation process to allow for choice. In ordinary aggregation, two random clusters merge and form a larger aggregate. In our implementation of choice, a target cluster and two candidate clusters are randomly selected and the target cluster merges with the larger of the two candidate clusters.We study the long-time asymptotic behavior and find that as in ordinary aggregation, the size density adheres to the standard scaling form. However, aggregation with choice exhibits a number of different features. First, the density of the smallest clusters exhibits anomalous scaling. Second, both the small-size and the large-size tailsmore » of the density are overpopulated, at the expense of the density of moderate-size clusters. Finally, we also study the complementary case where the smaller candidate cluster participates in the aggregation process and find an abundance of moderate clusters at the expense of small and large clusters. Additionally, we investigate aggregation processes with choice among multiple candidate clusters and a symmetric implementation where the choice is between two pairs of clusters.« less

First-principles characterization of potassium intercalation in the hexagonal 2H-MoS2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andersen, Amity; Kathmann, Shawn M.; Lilga, Michael A.

2012-01-12

Periodic density functional theory calculations were performed to study the structural and electronic properties of potassium intercalated into hexagonal MoS{sub 2} (2H-MoS{sub 2}). Metallic potassium (K) atoms are incrementally loaded in the hexagonal sites of the interstitial spaces between MoS2 sheets of the 2H-MoS{sub 2} bulk structure generating 2H-KxMoS2 (0.125 {<=} x {<=} 1.0) structures. To accommodate the potassium atoms, the interstitial spacing c parameter in the 2H-MoS{sub 2} bulk expands from 12.816 {angstrom} in 2H-MoS{sub 2} to 16.086 {angstrom} in 2H-K{sub 0.125}MoS{sub 2}. The second lowest potassium loading concentration (K{sub 0.25}MoS{sub 2}) results in the largest interstitial spacing expansionmore » (to c = 16.726 {angstrom}). Our calculations show that there is a small gradual contraction of the interstitial spacing as the potassium loading increases with c = 14.839 {angstrom} for KMoS{sub 2}. This interstitial contraction is correlated with an in-plane expansion of the MoS{sub 2} sheets, which is in good agreement with experimental X-ray diffraction (XRD) measurements. The electronic analysis shows that potassium readily donates its 4s electron to the conduction band of the 2H-K{sub x}MoS{sub 2}, and is largely ionic in character. As a result of the electron donation, the 2H-K{sub x}MoS{sub 2} system changes from a semiconductor to a more metallic system with increasing potassium intercalation. For loadings 0.25 {<=} x {<=} 0.625, triangular Mo-Mo-Mo moieties are prominent and tend to form rhombitrihexagonal motifs. Intercalation of H{sub 2}O molecules that solvate the K atoms is likely to occur in catalytic conditions. The inclusion of two H{sub 2}O molecules per K atom in the K{sub 0.25}MoS{sub 2} structure shows good agreement with XRD measurements.« less

Study of irradiation induced surface pattern and structural changes in Inconel 718 alloy

NASA Astrophysics Data System (ADS)

Wan, Hao; Si, Naichao; Zhao, Zhenjiang; Wang, Jian; Zhang, Yifei

2018-05-01

Helium ions irradiation induced surface pattern and structural changes of Inconel 718 alloy were studied with the combined utilization of atomic force microscopy (AFM), x-ray diffraction (XRD) and transmission electron microscopy (TEM). In addition, SRIM-2013 software was used to calculate the sputtering yield and detailed collision events. The result shows that, irradiation dose play an important role in altering the pattern of the surface. Enhanced irradiation aggravated the surface etching and increased the surface roughness. In ion irradiated layer, large amount of interstitials, vacancies and defect sinks were produced. Moreover, in samples with increasing dose irradiation, the dependence of interplanar spacing variation due to point defects clustering on sink density was discussed.

Di-μ-cyanido-tetra-cyanido(5,5,7,12,12,14-hexa-methyl-1,4,8,11-tetra-aza-cyclo-tetra-decane)[N-(quinolin-8-yl)quinoline-2-carboxamidato]diiron(III)nickel(II) 2.07-hydrate.

PubMed

Yang, Yuqi; Zhou, Hongbo; Shen, Xiaoping

2013-05-01

The asymmetric unit of the title complex, [Fe2Ni(C19H12N3O)2(CN)6(C16H36N4)]·2.07H2O, contains one [Fe(qcq)(CN)3](-) anion, half a [Ni(teta)](2+) cation and two partially occupied inter-stitial water mol-ecules [qcq(-) is the N-(quinolin-8-yl)quinoline-2-carboxamidate anion and teta is 5,5,7,12,12,14-hexa-methyl-1,4,8,11-tetra-aza-cyclo-tetra-deca-ne]. In the complex mol-ecule, two [Fe(qcq)(CN)3](-) anions additionally coordinate the central [Ni(teta)](2+) cation through cyanide groups in a trans mode, resulting in a trinuclear structure with the Ni(2+) cation lying on an inversion centre. The two inter-stitial water mol-ecules are partially occupied, with occupancy factors of 0.528 (10) and 0.506 (9). O-H⋯O and O-H⋯N hydrogen bonding involving the two lattice water molecules and the carbonyl function and a teta N atom in an adjacent cluster leads to the formation of layers extending parallel to (010).

Prion protein- and cardiac troponin T-marked interstitial cells from the adult myocardium spontaneously develop into beating cardiomyocytes

PubMed Central

Omatsu-Kanbe, Mariko; Nishino, Yuka; Nozuchi, Nozomi; Sugihara, Hiroyuki; Matsuura, Hiroshi

2014-01-01

Atypically-shaped cardiomyocytes (ACMs) constitute a novel subpopulation of beating heart cells found in the cultures of cardiac myocyte-removed crude fraction cells obtained from adult mouse cardiac ventricles. Although ~500 beating ACMs are observed under microscope in the cell cultures obtained from the hearts of either male or female mice, the origin of these cells in cardiac tissue has yet to be elucidated due to the lack of exclusive markers. In the present study, we demonstrate the efficacy of cellular prion protein (PrP) as a surface marker of ACMs. Cells expressing PrP at the plasma membrane in the culture of the crude fraction cells were found to develop into beating ACMs by themselves or fuse with each other to become larger multinuclear beating ACMs. Combining PrP with a cardiac-specific contractile protein cardiac troponin T (cTnT) allowed us to identify native ACMs in the mouse cardiac ventricles as either clustered or solitary cells. PrP- and cTnT-marked cells were also found in the adult, even aged, human cardiac ventricles. These findings suggest that interstitial cells marked by PrP and cTnT, native ACMs, exhibit life-long survival in the cardiac ventricles of both mice and humans. PMID:25466571

Effect of W self-implantation and He plasma exposure on early-stage defect and bubble formation in tungsten

NASA Astrophysics Data System (ADS)

Thompson, M.; Drummond, D.; Sullivan, J.; Elliman, R.; Kluth, P.; Kirby, N.; Riley, D.; Corr, C. S.

2018-06-01

To determine the effect of pre-existing defects on helium-vacancy cluster nucleation and growth, tungsten samples were self-implanted with 1 MeV tungsten ions at varying fluences to induce radiation damage, then subsequently exposed to helium plasma in the MAGPIE linear plasma device. Positron annihilation lifetime spectroscopy was performed both immediately after self-implantation, and again after plasma exposure. After self-implantation vacancies clusters were not observed near the sample surface (<30 nm). At greater depths (30–150 nm) vacancy clusters formed, and were found to increase in size with increasing W-ion fluence. After helium plasma exposure in the MAGPIE linear plasma device at ~300 K with a fluence of 1023 He-m‑2, deep (30–150 nm) vacancy clusters showed similar positron lifetimes, while shallow (<30 nm) clusters were not observed. The intensity of positron lifetime signals fell for most samples after plasma exposure, indicating that defects were filling with helium. The absence of shallow clusters indicates that helium requires pre-existing defects in order to drive vacancy cluster growth at 300 K. Further samples that had not been pre-damaged with W-ions were also exposed to helium plasma in MAGPIE across fluences from 1  ×  1022 to 1.2  ×  1024 He-m‑2. Samples exposed to fluences up to 1  ×  1023 He-m‑2 showed no signs of damage. Fluences of 5  ×  1023 He-m‑2 and higher showed significant helium-cluster formation within the first 30 nm, with positron lifetimes in the vicinity 0.5–0.6 ns. The sample temperature was significantly higher for these higher fluence exposures (~400 K) due to plasma heating. This higher temperature likely enhanced bubble formation by significantly increasing the rate interstitial helium clusters generate vacancies, which is we suspect is the rate-limiting step for helium-vacancy cluster/bubble nucleation in the absence of pre-existing defects.

Hierarchical poroelasticity: movement of interstitial fluid between porosity levels in bones.

PubMed

Cowin, Stephen C; Gailani, Gaffar; Benalla, Mohammed

2009-09-13

The governing equations for the theory of poroelastic materials with hierarchical pore space architecture and compressible constituents undergoing small deformations are developed. These equations are applied to the problem of determining the exchange of pore fluid between the vascular porosity (PV) and the lacunar-canalicular porosity (PLC) in bone tissue due to cyclic mechanical loading and blood pressure oscillations. The result is basic to the understanding of interstitial flow in bone tissue that, in turn, is basic to understanding of nutrient transport from the vasculature to the bone cells buried in the bone tissue and to the process of mechanotransduction by these cells. A formula for the volume of fluid that moves between the PLC and PV in a cyclic loading is obtained as a function of the cyclic mechanical loading and blood pressure oscillations. Formulas for the oscillating fluid pore pressure in both the PLC and the PV are obtained as functions of the two driving forces, the cyclic mechanical straining and the blood pressure, both with specified amplitude and frequency. The results of this study also suggest a PV permeability greater than 10(-9) m(2) and perhaps a little lower than 10(-8) m(2). Previous estimates of this permeability have been as small as 10(-14) m(2).

Understanding the role of the perivascular space in cerebral small vessel disease.

PubMed

Brown, Rosalind; Benveniste, Helene; Black, Sandra E; Charpak, Serge; Dichgans, Martin; Joutel, Anne; Nedergaard, Maiken; Smith, Kenneth J; Zlokovic, Berislav V; Wardlaw, Joanna M

2018-05-02

Small vessel diseases are a group of disorders that result from pathological alteration of the small blood vessels in the brain, including the small arteries, capillaries and veins. Of the 35-36 million people that are estimated to suffer from dementia worldwide, up to 65% have an SVD component. Furthermore, SVD causes 20-25% of strokes, worsens outcome after stroke and is a leading cause of disability, cognitive impairment and poor mobility. Yet the underlying cause(s) of SVD are not fully understood.Magnetic resonance imaging (MRI) has confirmed enlarged perivascular spaces (PVS) as a hallmark feature of SVD. In healthy tissue, these spaces are proposed to form part of a complex brain fluid drainage system which supports interstitial fluid exchange and may also facilitate clearance of waste products from the brain. The pathophysiological signature of PVS, and what this infers about their function and interaction with cerebral microcirculation, plus subsequent downstream effects on lesion development in the brain has not been established. Here we discuss the potential of enlarged PVS to be a unique biomarker for SVD and related brain disorders with a vascular component. We propose that widening of PVS suggests presence of peri-vascular cell debris and other waste products that forms part of a vicious cycle involving impaired cerebrovascular reactivity (CVR), blood-brain barrier (BBB) dysfunction, perivascular inflammation and ultimately impaired clearance of waste proteins from the interstitial fluid (ISF) space, leading to accumulation of toxins, hypoxia and tissue damage.Here, we outline current knowledge, questions and hypotheses regarding understanding the brain fluid dynamics underpinning dementia and stroke through the common denominator of SVD.

The impact of coexisting lung diseases on outcomes in patients with pathological Stage I non-small-cell lung cancer.

PubMed

Tao, Hiroyuki; Onoda, Hideko; Okabe, Kazunori; Matsumoto, Tsuneo

2018-06-01

Cigarette smoking is a well-known cause of interstitial lung disease (ILD), pulmonary emphysema and lung cancer. Coexisting pulmonary disease can affect prognosis in patients with lung cancer. The aim of this study was to determine the influence of pulmonary disease on outcomes in patients with a smoking history who had undergone surgery for pathological Stage I non-small-cell lung cancer. Medical records of 257 patients with a smoking history who underwent surgery for pathological Stage I non-small-cell lung cancer between June 2009 and December 2014 were reviewed. Coexisting ILDs were evaluated using high-resolution computed tomography. The degree of pulmonary emphysema was determined using image analysis software according to the Goddard classification. The impact of clinicopathological factors on outcome was evaluated. Among the 257 patients, ILDs were detected via high-resolution computed tomography in 60 (23.3%) patients; of these, usual interstitial pneumonia (UIP) patterns and non-UIP patterns were seen in 25 (9.7%) and 35 (13.6%) patients, respectively. The degree of pulmonary emphysema was classified as none, mild and moderate and included 50 (19.5%), 162 (63.0%) and 45 (17.5%) patients, respectively. The 5-year overall survival, cancer-specific survival and relapse-free survival were 80.7%, 88.0% and 74.9%, respectively, during a median follow-up period of 50.5 months. In multivariate analysis, the presence of a UIP pattern was shown to be an independent risk factor for poor outcome. The presence of a UIP-pattern ILD on high-resolution computed tomography images was shown to be a risk factor for poor outcome in patients with a smoking history who had undergone surgery for pathological Stage I non-small-cell lung cancer.

Computational Design of Clusters for Catalysis

NASA Astrophysics Data System (ADS)

Jimenez-Izal, Elisa; Alexandrova, Anastassia N.

2018-04-01

When small clusters are studied in chemical physics or physical chemistry, one perhaps thinks of the fundamental aspects of cluster electronic structure, or precision spectroscopy in ultracold molecular beams. However, small clusters are also of interest in catalysis, where the cold ground state or an isolated cluster may not even be the right starting point. Instead, the big question is: What happens to cluster-based catalysts under real conditions of catalysis, such as high temperature and coverage with reagents? Myriads of metastable cluster states become accessible, the entire system is dynamic, and catalysis may be driven by rare sites present only under those conditions. Activity, selectivity, and stability are highly dependent on size, composition, shape, support, and environment. To probe and master cluster catalysis, sophisticated tools are being developed for precision synthesis, operando measurements, and multiscale modeling. This review intends to tell the messy story of clusters in catalysis.

OGLE Collection of Star Clusters. New Objects in the Magellanic Bridge and the Outskirts of the Small Magellanic Cloud

NASA Astrophysics Data System (ADS)

Sitek, M.; Szymański, M. K.; Udalski, A.; Skowron, D. M.; Kostrzewa-Rutkowska, Z.; Skowron, J.; Karczmarek, P.; Cieślar, M.; Wyrzykowski, Ł.; Kozłowski, S.; Pietrukowicz, P.; Soszyński, I.; Mróz, P.; Pawlak, M.; Poleski, R.; Ulaczyk, K.

2017-12-01

The Magellanic System (MS) encompasses the nearest neighbors of the Milky Way, the Large (LMC) and Small (SMC) Magellanic Clouds, and the Magellanic Bridge (MBR). This system contains a diverse sample of star clusters. Their parameters, such as the spatial distribution, chemical composition and age distribution yield important information about the formation scenario of the whole Magellanic System. Using deep photometric maps compiled in the fourth phase of the Optical Gravitational Lensing Experiment (OGLE-IV) we present the most complete catalog of star clusters in the Magellanic System ever constructed from homogeneous, long time-scale photometric data. In this second paper of the series, we show the collection of star clusters found in the area of about 360 square degrees in the MBR and in the outer regions of the SMC. Our sample contains 198 visually identified star cluster candidates, 75 of which were not listed in any of the previously published catalogs. The new discoveries are mainly young small open clusters or clusters similar to associations.

Interstitial nephritis.

PubMed

Papper, S

1980-01-01

There are many causes of interstitial nephritis other than pyelonephritis. The term interstitial nephritis does not connote a single etiologic or pathogenetic mechanism; it rather arbitrarily places together a wider variety of renal diseases that have a predilection for early and major involvement of the renal interstitium. The prototype of acute interstitial nephritis is acute pyelonephritis. In addition, there is a drug-related acute interstitial disease that is probably of immunological nature and usually reverses with discontinuance of the offending drug. Chronic interstitial nephritis includes many diverse illnesses. Nonobstructive pyelonephritis occurs but its prevalence is debated. Analgesic abuse nephropathy is not rare and is potentially reversible. Papillary necrosis has many causes and a wide spectrum of clinical presentations. Heavy metals, such as lead, cause interstitial nephritis. Balkan nephropathy occurs in an endemic area and although not bacterial in origin is of unknown cause.

Self-evolving atomistic kinetic Monte Carlo simulations of defects in materials

DOE PAGES

Xu, Haixuan; Beland, Laurent K.; Stoller, Roger E.; ...

2015-01-29

The recent development of on-the-fly atomistic kinetic Monte Carlo methods has led to an increased amount attention on the methods and their corresponding capabilities and applications. In this review, the framework and current status of Self-Evolving Atomistic Kinetic Monte Carlo (SEAKMC) are discussed. SEAKMC particularly focuses on defect interaction and evolution with atomistic details without assuming potential defect migration/interaction mechanisms and energies. The strength and limitation of using an active volume, the key concept introduced in SEAKMC, are discussed. Potential criteria for characterizing an active volume are discussed and the influence of active volume size on saddle point energies ismore » illustrated. A procedure starting with a small active volume followed by larger active volumes was found to possess higher efficiency. Applications of SEAKMC, ranging from point defect diffusion, to complex interstitial cluster evolution, to helium interaction with tungsten surfaces, are summarized. A comparison of SEAKMC with molecular dynamics and conventional object kinetic Monte Carlo is demonstrated. Overall, SEAKMC is found to be complimentary to conventional molecular dynamics, especially when the harmonic approximation of transition state theory is accurate. However it is capable of reaching longer time scales than molecular dynamics and it can be used to systematically increase the accuracy of other methods such as object kinetic Monte Carlo. Furthermore, the challenges and potential development directions are also outlined.« less

The evolution of vacancy-type defects in silicon-on-insulator structures studied by positron annihilation spectroscopy

NASA Astrophysics Data System (ADS)

Coleman, P. G.; Nash, D.; Edwardson, C. J.; Knights, A. P.; Gwilliam, R. M.

2011-07-01

Variable-energy positron annihilation spectroscopy (VEPAS) has been applied to the study of the formation and evolution of vacancy-type defect structures in silicon (Si) and the 1.5 μm thick Si top layer of silicon-on-insulator (SOI) samples. The samples were implanted with 2 MeV Si ions at fluences between 1013 and 1015 cm-2, and probed in the as-implanted state and after annealing for 30 min at temperatures between 350 and 800 °C. In the case of SOI the ions were implanted such that their profile was predominantly in the insulating buried oxide layer, and thus their ability to combine with vacancies in the top Si layer, and that of other interstitials beyond the buried oxide, was effectively negated. No measurable differences in the positron response to the evolution of small clusters of n vacancies (Vn, n ˜ 3) in the top Si layer of the Si and SOI samples were observed after annealing up to 500 °C; at higher temperatures, however, this response persisted in the SOI samples as that in Si decreased toward zero. At 700 and 800 °C the damage in Si was below detectable levels, but the VEPAS response in the top Si layer in the SOI was consistent with the development of nanovoids.

Photoinduced Disaggregation of TiO2 Nanoparticles Enables Transdermal Penetration

PubMed Central

Bennett, Samuel W.; Zhou, Dongxu; Mielke, Randall; Keller, Arturo A.

2012-01-01

Under many aqueous conditions, metal oxide nanoparticles attract other nanoparticles and grow into fractal aggregates as the result of a balance between electrostatic and Van Der Waals interactions. Although particle coagulation has been studied for over a century, the effect of light on the state of aggregation is not well understood. Since nanoparticle mobility and toxicity have been shown to be a function of aggregate size, and generally increase as size decreases, photo-induced disaggregation may have significant effects. We show that ambient light and other light sources can partially disaggregate nanoparticles from the aggregates and increase the dermal transport of nanoparticles, such that small nanoparticle clusters can readily diffuse into and through the dermal profile, likely via the interstitial spaces. The discovery of photoinduced disaggregation presents a new phenomenon that has not been previously reported or considered in coagulation theory or transdermal toxicological paradigms. Our results show that after just a few minutes of light, the hydrodynamic diameter of TiO2 aggregates is reduced from ∼280 nm to ∼230 nm. We exposed pigskin to the nanoparticle suspension and found 200 mg kg−1 of TiO2 for skin that was exposed to nanoparticles in the presence of natural sunlight and only 75 mg kg−1 for skin exposed to dark conditions, indicating the influence of light on NP penetration. These results suggest that photoinduced disaggregation may have important health implications. PMID:23155401

Balance point characterization of interstitial fluid volume regulation.

PubMed

Dongaonkar, R M; Laine, G A; Stewart, R H; Quick, C M

2009-07-01

The individual processes involved in interstitial fluid volume and protein regulation (microvascular filtration, lymphatic return, and interstitial storage) are relatively simple, yet their interaction is exceedingly complex. There is a notable lack of a first-order, algebraic formula that relates interstitial fluid pressure and protein to critical parameters commonly used to characterize the movement of interstitial fluid and protein. Therefore, the purpose of the present study is to develop a simple, transparent, and general algebraic approach that predicts interstitial fluid pressure (P(i)) and protein concentrations (C(i)) that takes into consideration all three processes. Eight standard equations characterizing fluid and protein flux were solved simultaneously to yield algebraic equations for P(i) and C(i) as functions of parameters characterizing microvascular, interstitial, and lymphatic function. Equilibrium values of P(i) and C(i) arise as balance points from the graphical intersection of transmicrovascular and lymph flows (analogous to Guyton's classical cardiac output-venous return curves). This approach goes beyond describing interstitial fluid balance in terms of conservation of mass by introducing the concept of inflow and outflow resistances. Algebraic solutions demonstrate that P(i) and C(i) result from a ratio of the microvascular filtration coefficient (1/inflow resistance) and effective lymphatic resistance (outflow resistance), and P(i) is unaffected by interstitial compliance. These simple algebraic solutions predict P(i) and C(i) that are consistent with reported measurements. The present work therefore presents a simple, transparent, and general balance point characterization of interstitial fluid balance resulting from the interaction of microvascular, interstitial, and lymphatic function.

Adsorption and Formation of Small Na Clusters on Pristine and Double-Vacancy Graphene for Anodes of Na-Ion Batteries.

PubMed

Liang, Zhicong; Fan, Xiaofeng; Zheng, Weitao; Singh, David J

2017-05-24

Layered carbon is a likely anode material for Na-ion batteries (NIBs). Graphitic carbon has a low capacity of approximately 35 (mA h)/g due to the formation of NaC 64 . Using first-principles methods including van der Waals interactions, we analyze the adsorption of Na ions and clusters on graphene in the context of anodes. The interaction between Na ions and graphene is found to be weak. Small Na clusters are not stable on the surface of pristine graphene in the electrochemical environment of NIBs. However, we find that Na ions and clusters can be stored effectively on defected graphene that has double vacancies. In addition, the adsorption energy of small Na clusters near a double vacancy is found to decrease with increasing cluster size. With high concentrations of vacancies the capacity of Na on defective graphene is found to be as much as 10-30 times higher than that of graphitic carbon.

Clustering Methods with Qualitative Data: A Mixed Methods Approach for Prevention Research with Small Samples

PubMed Central

Henry, David; Dymnicki, Allison B.; Mohatt, Nathaniel; Allen, James; Kelly, James G.

2016-01-01

Qualitative methods potentially add depth to prevention research, but can produce large amounts of complex data even with small samples. Studies conducted with culturally distinct samples often produce voluminous qualitative data, but may lack sufficient sample sizes for sophisticated quantitative analysis. Currently lacking in mixed methods research are methods allowing for more fully integrating qualitative and quantitative analysis techniques. Cluster analysis can be applied to coded qualitative data to clarify the findings of prevention studies by aiding efforts to reveal such things as the motives of participants for their actions and the reasons behind counterintuitive findings. By clustering groups of participants with similar profiles of codes in a quantitative analysis, cluster analysis can serve as a key component in mixed methods research. This article reports two studies. In the first study, we conduct simulations to test the accuracy of cluster assignment using three different clustering methods with binary data as produced when coding qualitative interviews. Results indicated that hierarchical clustering, K-Means clustering, and latent class analysis produced similar levels of accuracy with binary data, and that the accuracy of these methods did not decrease with samples as small as 50. Whereas the first study explores the feasibility of using common clustering methods with binary data, the second study provides a “real-world” example using data from a qualitative study of community leadership connected with a drug abuse prevention project. We discuss the implications of this approach for conducting prevention research, especially with small samples and culturally distinct communities. PMID:25946969

Clustering Methods with Qualitative Data: a Mixed-Methods Approach for Prevention Research with Small Samples.

PubMed

Henry, David; Dymnicki, Allison B; Mohatt, Nathaniel; Allen, James; Kelly, James G

2015-10-01

Qualitative methods potentially add depth to prevention research but can produce large amounts of complex data even with small samples. Studies conducted with culturally distinct samples often produce voluminous qualitative data but may lack sufficient sample sizes for sophisticated quantitative analysis. Currently lacking in mixed-methods research are methods allowing for more fully integrating qualitative and quantitative analysis techniques. Cluster analysis can be applied to coded qualitative data to clarify the findings of prevention studies by aiding efforts to reveal such things as the motives of participants for their actions and the reasons behind counterintuitive findings. By clustering groups of participants with similar profiles of codes in a quantitative analysis, cluster analysis can serve as a key component in mixed-methods research. This article reports two studies. In the first study, we conduct simulations to test the accuracy of cluster assignment using three different clustering methods with binary data as produced when coding qualitative interviews. Results indicated that hierarchical clustering, K-means clustering, and latent class analysis produced similar levels of accuracy with binary data and that the accuracy of these methods did not decrease with samples as small as 50. Whereas the first study explores the feasibility of using common clustering methods with binary data, the second study provides a "real-world" example using data from a qualitative study of community leadership connected with a drug abuse prevention project. We discuss the implications of this approach for conducting prevention research, especially with small samples and culturally distinct communities.

Transbronchial cryobiopsy in interstitial lung disease: experience in 106 cases – how to do it

PubMed Central

Bango-Álvarez, Antonio; Torres-Rivas, Hector; Fernández-Fernández, Luis; Prieto, Amador; Sánchez, Inmaculada; Gil, Maria; Pando-Sandoval, Ana

2017-01-01

Transbronchial biopsy using forceps (TBB) is the first diagnostic technique performed on patients with interstitial lung disease (ILD). However, the small size of the samples and the presence of artefacts in the tissue obtained make the yield variable. Our objectives were 1) to attempt to reproduce transbronchial cryobiopsy under the same conditions with which we performed conventional TBB, that is, in the bronchoscopy unit without intubating the patient and without fluoroscopy or general anaesthesia; 2) to describe the method used for its execution; and 3) to analyse the diagnostic yield and its complications. We carried out a prospective study that included 106 patients with clinical and radiological features suggestive of ILD who underwent cryo-transbronchial lung biopsy (cryo-TBB) under moderate sedation without endotracheal intubation, general anaesthesia or use of fluoroscopy. We performed the procedure using two flexible bronchoscopes connected to two video processors, which we alternated until obtaining the number of desired samples. A definitive diagnosis was obtained in 91 patients (86%). As for complications, there were five pneumothoraces (4.7%) and in no case was there severe haemorrhage or exacerbation of the underlying interstitial disease. Cryo-TBB following our method is a minimally invasive, rapid, safe and economic technique that can be performed in a bronchoscopy suite under moderate sedation without the need for intubating the patient or using fluoroscopy and without requiring general anaesthesia. PMID:28344982

A case of acute kidney injury caused by granulomatous interstitial nephritis associated with sarcoidosis.

PubMed

Horino, Taro; Matsumoto, Tatsuki; Inoue, Kosuke; Ichii, Osamu; Terada, Yoshio

2018-05-01

Sarcoidosis affects multiple organs including lung, heart and kidney. Sarcoidosis causes hypercalcemia, hypergammaglobulinemia, and rarely, granulomatous interstitial nephritis, resulting in renal stromal damage. Granulomatous interstitial nephritis is characterized as interstitial nephritis with noncaseating epithelioid granulomas. Diagnosing granulomatous interstitial nephritis before patient's death is challenging; hence, only few cases proven by renal biopsy have been reported till date. We present a case of acute kidney injury caused by granulomatous interstitial nephritis as a renal manifestation of sarcoidosis proven by renal biopsy, which can be confirmed by 18 F-fluorodeoxyglucose positron emission tomography/computed tomography. Glucocorticoid therapy was helpful for improving and maintaining her renal function over a 6-year period.

Lowest-energy structures of (C60)nX (X=Li+,Na+,K+,Cl-) and (C60)nYCl (Y=Li,Na,K) clusters for n

PubMed

Hernández-Rojas, J; Bretón, J; Gomez Llorente, J M; Wales, D J

2004-12-22

Basin-hopping global optimization is used to find likely candidates for the lowest minima on the potential energy surface of (C(60))(n)X (X=Li(+),Na(+),K(+),Cl(-)) and (C(60))(n)YCl (Y=Li,Na,K) clusters with n

Evolution of anisotropy in bcc Fe distorted by interstitial boron

NASA Astrophysics Data System (ADS)

Gölden, Dominik; Zhang, Hongbin; Radulov, Iliya; Dirba, Imants; Komissinskiy, Philipp; Hildebrandt, Erwin; Alff, Lambert

2018-01-01

The evolution of magnetic anisotropy in bcc Fe as a function of interstitial boron atoms was investigated in thin films grown by molecular beam epitaxy. The thermodynamic nonequilibrium conditions during film growth allowed one to stabilize an interstitial boron content of about 14 at .% accompanied by lattice tetragonalization. The c /a ratio scaled linearly with the boron content up to a maximum value of 1.05 at 300 °C substrate growth temperature, with a room-temperature magnetization of. In contrast to nitrogen interstitials, the magnetic easy axis remained in-plane with an anisotropy of approximately -5.1 ×106erg /cm3 . Density functional theory calculations using the measured lattice parameters confirm this value and show that boron local ordering indeed favors in-plane magnetization. Given the increased temperature stability of boron interstitials as compared to nitrogen interstitials, this study will help to find possible ways to manipulate boron interstitials into a more favorable local order.

Chylothorax in dermatomyositis complicated with interstitial pneumonia.

PubMed

Isoda, Kentaro; Kiboshi, Takao; Shoda, Takeshi

2017-04-01

Chylothorax is a disease in which chyle leaks and accumulates in the thoracic cavity. Interstitial pneumonia and pneumomediastinum are common thoracic manifestations of dermatomyositis, but chylothorax complicated with dermatomyositis is not reported. We report a case of dermatomyositis with interstitial pneumonia complicated by chylothorax. A 77-year-old woman was diagnosed as dermatomyositis with Gottron's papules, skin ulcers, anti-MDA5 antibody and rapid progressive interstitial pneumonia. Treatment with betamethasone, tacrolimus and intravenous high-dose cyclophosphamide was initiated, and her skin symptoms and interstitial pneumonia improved once. However, right-sided chylothorax began to accumulate and gradually increase, and at the same time, her interstitial pneumonia began to exacerbate, and skin ulcers began to reappear on her fingers and auricles. Although her chylothorax improved by fasting and parenteral nutrition, she died due to further exacerbations of dermatomyositis and interstitial pneumonia in spite of steroid pulse therapy, increase in the betamethasone dosage, additional intravenous high-dose cyclophosphamide and plasma pheresis. An autopsy showed no lesions such as malignant tumors in the thoracic cavity. This is the first report of chylothorax complicated by dermatomyositis with interstitial pneumonia.

Euchromatic Transposon Insertions Trigger Production of Novel Pi- and Endo-siRNAs at the Target Sites in the Drosophila Germline

PubMed Central

Olovnikov, Ivan; Abramov, Yuri; Kalmykova, Alla

2014-01-01

The control of transposable element (TE) activity in germ cells provides genome integrity over generations. A distinct small RNA–mediated pathway utilizing Piwi-interacting RNAs (piRNAs) suppresses TE expression in gonads of metazoans. In the fly, primary piRNAs derive from so-called piRNA clusters, which are enriched in damaged repeated sequences. These piRNAs launch a cycle of TE and piRNA cluster transcript cleavages resulting in the amplification of piRNA and TE silencing. Using genome-wide comparison of TE insertions and ovarian small RNA libraries from two Drosophila strains, we found that individual TEs inserted into euchromatic loci form novel dual-stranded piRNA clusters. Formation of the piRNA-generating loci by active individual TEs provides a more potent silencing response to the TE expansion. Like all piRNA clusters, individual TEs are also capable of triggering the production of endogenous small interfering (endo-si) RNAs. Small RNA production by individual TEs spreads into the flanking genomic regions including coding cellular genes. We show that formation of TE-associated small RNA clusters can down-regulate expression of nearby genes in ovaries. Integration of TEs into the 3′ untranslated region of actively transcribed genes induces piRNA production towards the 3′-end of transcripts, causing the appearance of genic piRNA clusters, a phenomenon that has been reported in different organisms. These data suggest a significant role of TE-associated small RNAs in the evolution of regulatory networks in the germline. PMID:24516406

Kinetics of Aggregation with Choice

DOE PAGES

Ben-Naim, Eli; Krapivsky, Paul

2016-12-01

Here we generalize the ordinary aggregation process to allow for choice. In ordinary aggregation, two random clusters merge and form a larger aggregate. In our implementation of choice, a target cluster and two candidate clusters are randomly selected and the target cluster merges with the larger of the two candidate clusters.We study the long-time asymptotic behavior and find that as in ordinary aggregation, the size density adheres to the standard scaling form. However, aggregation with choice exhibits a number of different features. First, the density of the smallest clusters exhibits anomalous scaling. Second, both the small-size and the large-size tailsmore » of the density are overpopulated, at the expense of the density of moderate-size clusters. Finally, we also study the complementary case where the smaller candidate cluster participates in the aggregation process and find an abundance of moderate clusters at the expense of small and large clusters. Additionally, we investigate aggregation processes with choice among multiple candidate clusters and a symmetric implementation where the choice is between two pairs of clusters.« less

Proteomics detection of S100A6 in tumor tissue interstitial fluid and evaluation of its potential as a biomarker of cholangiocarcinoma.

PubMed

Onsurathum, Sudarat; Haonon, Ornuma; Pinlaor, Porntip; Pairojkul, Chawalit; Khuntikeo, Narong; Thanan, Raynoo; Roytrakul, Sittiruk; Pinlaor, Somchai

2018-04-01

Tumor interstitial fluid contains tumor-specific proteins that may be useful biomarkers for cancers. In this study, we identified proteins present in cholangiocarcinoma interstitial fluid. Proteins derived from three samples of tumor interstitial fluid and paired samples of adjacent normal interstitial fluid from cholangiocarcinoma patients were subjected to two-dimensional liquid chromatography with tandem mass spectrometry. Candidate proteins were selected based on a greater than twofold change in expression levels between tumor interstitial fluid and normal interstitial fluid. Upregulation of six proteins in tumor interstitial fluid, including S100 calcium binding protein A6 (S100A6), S100 calcium binding protein A9, aldo-keto reductase family 1 member C4, neuropilin-1, 14-3-3 zeta/delta, and triosephosphate isomerase was assessed by western blot and immunohistochemistry. Their potential as markers was evaluated in human cholangiocarcinoma tissue arrays, and in serum using enzyme-linked immunosorbent assay. Expression of S100A6 was higher in tumor interstitial fluid than in normal interstitial fluid and showed the highest positive rate (98.96%) in cholangiocarcinoma tissues. Serum levels of S100A6 did not differ between cholangitis and cholangiocarcinoma patients, but were significantly higher than in healthy individuals ( p < 0.0001). In cholangiocarcinoma cases, S100A6 level was associated with vascular invasion ( p = 0.007) and could distinguish cholangiocarcinoma patients from healthy individuals as effectively as the carbohydrate antigen 19-9. In addition, potential for drug treatment targeting S100A6 and other candidate proteins was also demonstrated using STITCH analysis. In conclusion, proteomics analysis of tumor interstitial fluid could be a new approach for biomarker discovery, and S100A6 is a potential risk marker for screening of cholangiocarcinoma.

Pulmonary fibrosis in a carpenter with long-lasting exposure to fiberglass.

PubMed

Takahashi, T; Munakata, M; Takekawa, H; Homma, Y; Kawakami, Y

1996-11-01

A 56-year-old male carpenter had a history of glass fiber inhalation for 41 years without any protective device. His chest radiograph showed small nodular opacities in lower lung fields and multiple cystic lesions and low attenuation areas in upper lung fields. Light and polarizing microscopic examinations of his transbronchial lung biopsy specimen revealed mild interstitial fibrosis and mononuclear cell infiltration in alveolar walls without birefringent substances. However, widespread depositions of small glass fibers (< 2.5 microns in length and 0.3 micron in diameter) were detected by analytical electron microscopy, which suggested their possible contribution to the development of his pulmonary fibrosis.

OGLE Collection of Star Clusters. New Objects in the Outskirts of the Large Magellanic Cloud

NASA Astrophysics Data System (ADS)

Sitek, M.; Szymański, M. K.; Skowron, D. M.; Udalski, A.; Kostrzewa-Rutkowska, Z.; Skowron, J.; Karczmarek, P.; Cieślar, M.; Wyrzykowski, Ł.; Kozłowski, S.; Pietrukowicz, P.; Soszyński, I.; Mróz, P.; Pawlak, M.; Poleski, R.; Ulaczyk, K.

2016-09-01

The Magellanic System (MS), consisting of the Large Magellanic Cloud (LMC), the Small Magellanic Cloud (SMC) and the Magellanic Bridge (MBR), contains diverse sample of star clusters. Their spatial distribution, ages and chemical abundances may provide important information about the history of formation of the whole System. We use deep photometric maps derived from the images collected during the fourth phase of the Optical Gravitational Lensing Experiment (OGLE-IV) to construct the most complete catalog of star clusters in the Large Magellanic Cloud using the homogeneous photometric data. In this paper we present the collection of star clusters found in the area of about 225 square degrees in the outer regions of the LMC. Our sample contains 679 visually identified star cluster candidates, 226 of which were not listed in any of the previously published catalogs. The new clusters are mainly young small open clusters or clusters similar to associations.

Investigation of Metal and Metal Oxide Clusters Small Enough to Constitute the Critical Size for Gas Phase Nucleation in Combustion Processes.

DTIC Science & Technology

1980-11-01

Ao-A093 950 NORTHWESTERN UNIV EVANSTON IL DEPT OF M4ECHANICAL ND-ETC F/S 7/4 INVESTIGATION OF 1ETAL AND METAL OXIDE CLUSTERS S1ALL ENOUGH TO--ETC(U...34 " 18. SUPPLEMENTARY NOTES 19. KEY WORDS (Continue on reveroe side if necessary snd Identify by block number) Clusters , Nucleation, Molecular Beam, Free...contract a variety of techniques have been employed to study the properties of small atomic and molecular clusters formed in the gas phase via

Ultra-small rhenium clusters supported on graphene.

PubMed

Miramontes, Orlando; Bonafé, Franco; Santiago, Ulises; Larios-Rodriguez, Eduardo; Velázquez-Salazar, Jesús J; Mariscal, Marcelo M; Yacaman, Miguel José

2015-03-28

The adsorption of very small rhenium clusters (2-13 atoms) supported on graphene was studied by high-angle annular dark field-scanning transmission electron microscopy (HAADF-STEM). The atomic structure of the clusters was fully resolved with the aid of density functional theory calculations and STEM simulations. It was found that octahedral and tetrahedral structures work as seeds to obtain more complex morphologies. Finally, a detailed analysis of the electronic structure suggested that a higher catalytic effect can be expected in Re clusters when adsorbed on graphene than in isolated ones.

Ultra-small rhenium clusters supported on graphene

PubMed Central

Miramontes, Orlando; Bonafé, Franco; Santiago, Ulises; Larios-Rodriguez, Eduardo; Velázquez-Salazar, Jesús J.; Mariscal, Marcelo M.; Yacaman, Miguel José

2015-01-01

The adsorption of very small rhenium clusters (2 – 13 atoms) supported on graphene was studied with high annular dark field - scanning transmission electron microscopy (HAADF-STEM). The atomic structure of the clusters was fully resolved with the aid of density functional calculations and STEM simulations. It was found that octahedral and tetrahedral structures work as seeds to obtain more complex morphologies. Finally, a detailed analysis of the electronic structure suggested that a higher catalytic effect can be expected in Re clusters when adsorbed on graphene than in isolated ones. PMID:25721176

Cooling system for continuous metal casting machines

DOEpatents

Draper, Robert; Sumpman, Wayne C.; Baker, Robert J.; Williams, Robert S.

1988-01-01

A continuous metal caster cooling system is provided in which water is supplied in jets from a large number of small nozzles 19 against the inner surface of rim 13 at a temperature and with sufficient pressure that the velocity of the jets is sufficiently high that the mode of heat transfer is substantially by forced convection, the liquid being returned from the cooling chambers 30 through return pipes 25 distributed interstitially among the nozzles.

Cooling system for continuous metal casting machines

DOEpatents

Draper, R.; Sumpman, W.C.; Baker, R.J.; Williams, R.S.

1988-06-07

A continuous metal caster cooling system is provided in which water is supplied in jets from a large number of small nozzles against the inner surface of rim at a temperature and with sufficient pressure that the velocity of the jets is sufficiently high that the mode of heat transfer is substantially by forced convection, the liquid being returned from the cooling chambers through return pipes distributed interstitially among the nozzles. 9 figs.

Diffusion of vaporous guests into a seemingly non-porous organic crystal

DOE Office of Scientific and Technical Information (OSTI.GOV)

Herbert, Simon A.; Janiak, Agnieszka; Thallapally, Praveen K.

2014-10-07

In this research, the tetragonal apohost phase of p-tert-butyltetramethoxythiacalix[4]arene absorbs hydrochloric acid and iodine. These guest molecules occupy different sites in the solid-state structure -- either within the small intrinsic voids of the macrocycle or within the interstitial spaces between the host molecules. This study illustrates the dynamic deformation of the host, providing strong mechanistic insight into the diffusion of guests into this seemingly non-porous material.

Transient regulation of three clustered tomato class-I small heat-shock chaperone genes by ethylene is mediated by SIMADS-RIN transcription factor

USDA-ARS?s Scientific Manuscript database

An intronless cluster of three class I small heat shock protein (sHSP) chaperone genes, Sl17.6, Sl20.0 and Sl20.1, resident on the short arm of chromosome 6 in tomato, was previously characterized (Goyal et al., 2012). This shsp chaperone gene cluster was found decorated with cis sequences known to ...

Cluster-to-cluster transformation among Au6, Au8 and Au11 nanoclusters.

PubMed

Ren, Xiuqing; Fu, Junhong; Lin, Xinzhang; Fu, Xuemei; Yan, Jinghui; Wu, Ren'an; Liu, Chao; Huang, Jiahui

2018-05-22

We present the cluster-to-cluster transformations among three gold nanoclusters, [Au6(dppp)4]2+ (Au6), [Au8(dppp)4Cl2]2+ (Au8) and [Au11(dppp)5]3+ (Au11). The conversion process follows a rule that states that the transformation of a small cluster to a large cluster is achieved through an oxidation process with an oxidizing agent (H2O2) or with heating, while the conversion of a large cluster to a small one occurs through a reduction process with a reducing agent (NaBH4). All the reactions were monitored using UV-Vis spectroscopy and ESI-MS. This work may provide an alternative approach to the synthesis of novel gold nanoclusters and a further understanding of the structural transformation relationship of gold nanoclusters.

Quasi-planar elemental clusters in pair interactions approximation

NASA Astrophysics Data System (ADS)

Chkhartishvili, Levan

2016-01-01

The pair-interactions approximation, when applied to describe elemental clusters, only takes into account bonding between neighboring atoms. According to this approach, isomers of wrapped forms of 2D clusters - nanotubular and fullerene-like structures - and truly 3D clusters, are generally expected to be more stable than their quasi-planar counterparts. This is because quasi-planar clusters contain more peripheral atoms with dangling bonds and, correspondingly, fewer atoms with saturated bonds. However, the differences in coordination numbers between central and peripheral atoms lead to the polarization of bonds. The related corrections to the molar binding energy can make small, quasi-planar clusters more stable than their 2D wrapped allotropes and 3D isomers. The present work provides a general theoretical frame for studying the relative stability of small elemental clusters within the pair interactions approximation.

Myeloid Clusters Are Associated with a Pro-Metastatic Environment and Poor Prognosis in Smoking-Related Early Stage Non-Small Cell Lung Cancer

PubMed Central

Zhang, Wang; Pal, Sumanta K.; Liu, Xueli; Yang, Chunmei; Allahabadi, Sachin; Bhanji, Shaira; Figlin, Robert A.; Yu, Hua; Reckamp, Karen L.

2013-01-01

Background This study aimed to understand the role of myeloid cell clusters in uninvolved regional lymph nodes from early stage non-small cell lung cancer patients. Methods Uninvolved regional lymph node sections from 67 patients with stage I–III resected non-small cell lung cancer were immunostained to detect myeloid clusters, STAT3 activity and occult metastasis. Anthracosis intensity, myeloid cluster infiltration associated with anthracosis and pSTAT3 level were scored and correlated with patient survival. Multivariate Cox regression analysis was performed with prognostic variables. Human macrophages were used for in vitro nicotine treatment. Results CD68+ myeloid clusters associated with anthracosis and with an immunosuppressive and metastasis-promoting phenotype and elevated overall STAT3 activity were observed in uninvolved lymph nodes. In patients with a smoking history, myeloid cluster score significantly correlated with anthracosis intensity and pSTAT3 level (P<0.01). Nicotine activated STAT3 in macrophages in long-term culture. CD68+ myeloid clusters correlated and colocalized with occult metastasis. Myeloid cluster score was an independent prognostic factor (P = 0.049) and was associated with survival by Kaplan-Maier estimate in patients with a history of smoking (P = 0.055). The combination of myeloid cluster score with either lymph node stage or pSTAT3 level defined two populations with a significant difference in survival (P = 0.024 and P = 0.004, respectively). Conclusions Myeloid clusters facilitate a pro-metastatic microenvironment in uninvolved regional lymph nodes and associate with occult metastasis in early stage non-small cell lung cancer. Myeloid cluster score is an independent prognostic factor for survival in patients with a history of smoking, and may present a novel method to inform therapy choices in the adjuvant setting. Further validation studies are warranted. PMID:23717691

First-principles investigation of the dissociation and coupling of methane on small copper clusters: Interplay of collision dynamics and geometric and electronic effects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Varghese, Jithin J.; Mushrif, Samir H., E-mail: shmushrif@ntu.edu.sg

Small metal clusters exhibit unique size and morphology dependent catalytic activity. The search for alternate minimum energy pathways and catalysts to transform methane to more useful chemicals and carbon nanomaterials led us to investigate collision induced dissociation of methane on small Cu clusters. We report here for the first time, the free energy barriers for the collision induced activation, dissociation, and coupling of methane on small Cu clusters (Cu{sub n} where n = 2–12) using ab initio molecular dynamics and metadynamics simulations. The collision induced activation of the stretching and bending vibrations of methane significantly reduces the free energy barriermore » for its dissociation. Increase in the cluster size reduces the barrier for dissociation of methane due to the corresponding increase in delocalisation of electron density within the cluster, as demonstrated using the electron localisation function topology analysis. This enables higher probability of favourable alignment of the C–H stretching vibration of methane towards regions of high electron density within the cluster and makes higher number of sites available for the chemisorption of CH{sub 3} and H upon dissociation. These characteristics contribute in lowering the barrier for dissociation of methane. Distortion and reorganisation of cluster geometry due to high temperature collision dynamics disturb electron delocalisation within them and increase the barrier for dissociation. Coupling reactions of CH{sub x} (x = 1–3) species and recombination of H with CH{sub x} have free energy barriers significantly lower than complete dehydrogenation of methane to carbon. Thus, competition favours the former reactions at high hydrogen saturation on the clusters.« less

Influence of reactive gas admixture on transition metal cluster nucleation in a gas aggregation cluster source

NASA Astrophysics Data System (ADS)

Peter, Tilo; Polonskyi, Oleksandr; Gojdka, Björn; Mohammad Ahadi, Amir; Strunskus, Thomas; Zaporojtchenko, Vladimir; Biederman, Hynek; Faupel, Franz

2012-12-01

We quantitatively assessed the influence of reactive gases on the formation processes of transition metal clusters in a gas aggregation cluster source. A cluster source based on a 2 in. magnetron is used to study the production rate of titanium and cobalt clusters. Argon served as working gas for the DC magnetron discharge, and a small amount of reactive gas (oxygen and nitrogen) is added to promote reactive cluster formation. We found that the cluster production rate depends strongly on the reactive gas concentration for very small amounts of reactive gas (less than 0.1% of total working gas), and no cluster formation takes place in the absence of reactive species. The influence of discharge power, reactive gas concentration, and working gas pressure are investigated using a quartz micro balance in a time resolved manner. The strong influence of reactive gas is explained by a more efficient formation of nucleation seeds for metal-oxide or nitride than for pure metal.

Alveolar epithelial cells undergo epithelial-mesenchymal transition in acute interstitial pneumonia: a case report

PubMed Central

2014-01-01

Background Acute interstitial pneumonia is a rare interstitial lung disease that rapidly progresses to respiratory failure or death. Several studies showed that myofibroblast plays an important role in the evolution of diffuse alveolar damage, which is the typical feature of acute interstitial pneumonia. However, no evidence exists whether alveolar epithelial cells are an additional source of myofibroblasts via epithelial-mesenchymal transition in acute interstitial pneumonia. Case presentation In this report, we present a case of acute interstitial pneumonia in a previously healthy 28-year-old non-smoking woman. Chest high-resolution computed tomography scan showed bilateral and diffusely ground-glass opacification. The biopsy was performed on the fifth day of her hospitalization, and results showed manifestation of acute exudative phase of diffuse alveolar damage characterized by hyaline membrane formation. On the basis of the preliminary diagnosis of acute interstitial pneumonia, high-dose glucocorticoid was used. However, this drug showed poor clinical response and could improve the patient’s symptoms only during the early phase. The patient eventually died of respiratory dysfunction. Histological findings in autopsy were consistent with the late form of acute interstitial pneumonia. Conclusions The results in this study revealed that alveolar epithelial cells underwent epithelial-mesenchymal transition and may be an important origin of myofibroblasts in the progression of acute interstitial pneumonia. Conducting research on the transformation of alveolar epithelial cells into myofibroblasts in the lung tissue of patients with acute interstitial pneumonia may be beneficial for the treatment of this disease. However, to our knowledge, no research has been conducted on this topic. PMID:24755111

Mass Distribution in Galaxy Cluster Cores

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hogan, M. T.; McNamara, B. R.; Pulido, F.

Many processes within galaxy clusters, such as those believed to govern the onset of thermally unstable cooling and active galactic nucleus feedback, are dependent upon local dynamical timescales. However, accurate mapping of the mass distribution within individual clusters is challenging, particularly toward cluster centers where the total mass budget has substantial radially dependent contributions from the stellar ( M {sub *}), gas ( M {sub gas}), and dark matter ( M {sub DM}) components. In this paper we use a small sample of galaxy clusters with deep Chandra observations and good ancillary tracers of their gravitating mass at both largemore » and small radii to develop a method for determining mass profiles that span a wide radial range and extend down into the central galaxy. We also consider potential observational pitfalls in understanding cooling in hot cluster atmospheres, and find tentative evidence for a relationship between the radial extent of cooling X-ray gas and nebular H α emission in cool-core clusters. At large radii the entropy profiles of our clusters agree with the baseline power law of K ∝ r {sup 1.1} expected from gravity alone. At smaller radii our entropy profiles become shallower but continue with a power law of the form K ∝ r {sup 0.67} down to our resolution limit. Among this small sample of cool-core clusters we therefore find no support for the existence of a central flat “entropy floor.”.« less

Small Sample Performance of Bias-corrected Sandwich Estimators for Cluster-Randomized Trials with Binary Outcomes

PubMed Central

Li, Peng; Redden, David T.

2014-01-01

SUMMARY The sandwich estimator in generalized estimating equations (GEE) approach underestimates the true variance in small samples and consequently results in inflated type I error rates in hypothesis testing. This fact limits the application of the GEE in cluster-randomized trials (CRTs) with few clusters. Under various CRT scenarios with correlated binary outcomes, we evaluate the small sample properties of the GEE Wald tests using bias-corrected sandwich estimators. Our results suggest that the GEE Wald z test should be avoided in the analyses of CRTs with few clusters even when bias-corrected sandwich estimators are used. With t-distribution approximation, the Kauermann and Carroll (KC)-correction can keep the test size to nominal levels even when the number of clusters is as low as 10, and is robust to the moderate variation of the cluster sizes. However, in cases with large variations in cluster sizes, the Fay and Graubard (FG)-correction should be used instead. Furthermore, we derive a formula to calculate the power and minimum total number of clusters one needs using the t test and KC-correction for the CRTs with binary outcomes. The power levels as predicted by the proposed formula agree well with the empirical powers from the simulations. The proposed methods are illustrated using real CRT data. We conclude that with appropriate control of type I error rates under small sample sizes, we recommend the use of GEE approach in CRTs with binary outcomes due to fewer assumptions and robustness to the misspecification of the covariance structure. PMID:25345738

Fuzzy-C-Means Clustering Based Segmentation and CNN-Classification for Accurate Segmentation of Lung Nodules

PubMed

K, Jalal Deen; R, Ganesan; A, Merline

2017-07-27

Objective: Accurate segmentation of abnormal and healthy lungs is very crucial for a steadfast computer-aided disease diagnostics. Methods: For this purpose a stack of chest CT scans are processed. In this paper, novel methods are proposed for segmentation of the multimodal grayscale lung CT scan. In the conventional methods using Markov–Gibbs Random Field (MGRF) model the required regions of interest (ROI) are identified. Result: The results of proposed FCM and CNN based process are compared with the results obtained from the conventional method using MGRF model. The results illustrate that the proposed method can able to segment the various kinds of complex multimodal medical images precisely. Conclusion: However, in this paper, to obtain an exact boundary of the regions, every empirical dispersion of the image is computed by Fuzzy C-Means Clustering segmentation. A classification process based on the Convolutional Neural Network (CNN) classifier is accomplished to distinguish the normal tissue and the abnormal tissue. The experimental evaluation is done using the Interstitial Lung Disease (ILD) database. Creative Commons Attribution License

Fuzzy-C-Means Clustering Based Segmentation and CNN-Classification for Accurate Segmentation of Lung Nodules

PubMed Central

K, Jalal Deen; R, Ganesan; A, Merline

2017-01-01

Objective: Accurate segmentation of abnormal and healthy lungs is very crucial for a steadfast computer-aided disease diagnostics. Methods: For this purpose a stack of chest CT scans are processed. In this paper, novel methods are proposed for segmentation of the multimodal grayscale lung CT scan. In the conventional methods using Markov–Gibbs Random Field (MGRF) model the required regions of interest (ROI) are identified. Result: The results of proposed FCM and CNN based process are compared with the results obtained from the conventional method using MGRF model. The results illustrate that the proposed method can able to segment the various kinds of complex multimodal medical images precisely. Conclusion: However, in this paper, to obtain an exact boundary of the regions, every empirical dispersion of the image is computed by Fuzzy C-Means Clustering segmentation. A classification process based on the Convolutional Neural Network (CNN) classifier is accomplished to distinguish the normal tissue and the abnormal tissue. The experimental evaluation is done using the Interstitial Lung Disease (ILD) database. PMID:28749127

Factors Affecting Impact Toughness in Stabilized Intermediate Purity 21Cr Ferritic Stainless Steels and Their Simulated Heat-Affected Zones

NASA Astrophysics Data System (ADS)

Anttila, Severi; Alatarvas, Tuomas; Porter, David A.

2017-12-01

The correlation between simulated weld heat-affected zone microstructures and toughness parameters has been investigated in four intermediate purity 21Cr ferritic stainless steels stabilized with titanium and niobium either separately or in combination. Extensive Charpy V impact toughness testing was carried out followed by metallography including particle analysis using electron microscopy. The results confirmed that the grain size and the number density of particle clusters rich in titanium nitride and carbide with an equivalent circular diameter of 2 µm or more are statistically the most critical factors influencing the ductile-to-brittle transition temperature. Other inclusions and particle clusters, as well as grain boundary precipitates, are shown to be relatively harmless. Stabilization with niobium avoids large titanium-rich inclusions and also suppresses excessive grain growth in the heat-affected zone when reasonable heat inputs are used. Thus, in order to maximize the limited heat-affected zone impact toughness of 21Cr ferritic stainless steels containing 380 to 450 mass ppm of interstitials, the stabilization should be either titanium free or the levels of titanium and nitrogen should be moderated.

Geometrically Necessary Dislocation Density Evolution in Interstitial Free Steel at Small Plastic Strains

NASA Astrophysics Data System (ADS)

Kundu, Amrita; Field, David P.

2018-06-01

Measurement of geometrically necessary dislocation (GND) density using electron backscatter diffraction (EBSD) has become rather common place in modern metallurgical research. The utility of this measure as an indicator of the expected flow behavior of the material is not obvious. Incorporation of total dislocation density into the Taylor equation relating flow stress to dislocation density is generally accepted, but this does not automatically extend to a similar relationship for the GND density. This is discussed in the present work using classical equations for isotropic metal plasticity in a rather straight-forward theoretical framework. This investigation examines the development of GND structure in a commercially produced interstitial free steel subject to tensile deformation. Quantification of GND density was carried out using conventional EBSD at various strain levels on the surface of a standard dog-bone-shaped tensile specimen. There is linear increase of the average GND density with imposed macroscopic strain. This is in agreement with the established framework.

Multi-Phonon Relaxation of H^- Local Modes in CaF_2

NASA Astrophysics Data System (ADS)

Davison, C. P.; Happek, U.; Campbell, J. A.; Engholm, J. R.; Schwettman, H. A.

1998-03-01

Local modes play an important role in the relaxation of vibrational modes of small molecules in solids (J.R. Engholm, C.W. Rella, H.A. Schwettman, and U. Happek; Phys. Rev. Lett. 77), 1302 (1996)., but only few attempts have been reported to study the relaxation of these local modes. Here we report on experiments to investigate the non-radiative relaxation of H^- local modes in CaF_2. Using a pump-probe technique, saturation experiments on the H^- local modes, both interstitial and substitutional, were performed at the Stanford Free Electron Laser Center. At low temperature we find a relaxation time T1 of 45 psec for the substitutional H^- local mode, and a more rapid relaxation for the interstitial H^- local modes next to La^3+ and Lu^3+ impurities. Information on the decay channels of the local modes are obtained from the characteristic temperature dependence of the relaxation rates. This work is supported in part by the ONR, Grant No. N00014-94-1024.

First reported association of chronic lymphocytic leukaemia and interstitial granulomatous dermatitis.

PubMed

Riaz, Irbaz Bin; Kamal, Muhammad Umar; Segal, Robert J; Anwer, Faiz

2016-05-18

Interstitial granulomatous dermatitis (IGD), a rare disease, is well known to be associated with connective tissue disorders, malignancies and several drugs. We describe this first case of IGD in association with chronic lymphocytic leukaemia/small lymphocytic lymphoma (CLL/SLL). A 66-year-old woman with a 6-year history of untreated CLL/SLL, presented with a 2-month history of progressively worsening eruption of the left thigh, along with fatigue, lymphadenopathy and night sweats. Skin biopsy showed findings consistent with IGD and infiltration of CLL. The eruption was non-responsive to treatment with antibiotics and local steroids. There was a significant improvement in the rash after an initial cycle of chemotherapy (combination therapy with bendamustine and rituximab) and complete resolution by the third cycle, for the treatment of her CLL. We suggest that the possibility of an underlying haematological malignancy should be investigated in patients with a skin rash non-responsive to conventional therapy. 2016 BMJ Publishing Group Ltd.

Tunneling interstitial impurity in iron-chalcogenide-based superconductors

NASA Astrophysics Data System (ADS)

Huang, Huaixiang; Zhang, Degang; Gao, Yi; Ren, Wei; Ting, C. S.

2016-02-01

A pronounced local in-gap zero-energy bound state (ZBS) has been observed by recent scanning tunneling microscopy experiments on the interstitial Fe impurity (IFI) and its nearest-neighboring sites in an FeTe0.5Se0.5 superconducting (SC) compound. By introducing an impurity mechanism, the so-called tunneling impurity, and based on the Bogoliubov-de Gennes equations, we investigate the low-lying energy states of the IFI and the underlying Fe plane. The calculations are performed in the presence as well as in the absence of a magnetic field. We find the IFI-induced ZBS does not shift or split in a magnetic field as long as the tunneling parameter between the IFI and the Fe plane is sufficiently small and the Fe plane is deep in the SC state. Our results are in good agreement with experiments. We also show that in the underdoped cases, modulation of the spin density wave or charge density wave will suppress the intensity of the ZBS on the Fe plane in a vortex state.

Digesting a Path Forward: The Utility of Collagenase Tumor Treatment for Improved Drug Delivery.

PubMed

Dolor, Aaron; Szoka, Francis C

2018-06-04

Collagen and hyaluronan are the most abundant components of the extracellular matrix (ECM) and their overexpression in tumors is linked to increased tumor growth and metastasis. These ECM components contribute to a protective tumor microenvironment by supporting a high interstitial fluid pressure and creating a tortuous setting for the convection and diffusion of chemotherapeutic small molecules, antibodies, and nanoparticles in the tumor interstitial space. This review focuses on the research efforts to deplete extracellular collagen with collagenases to normalize the tumor microenvironment. Although collagen synthesis inhibitors are in clinical development, the use of collagenases is contentious and clinically untested in cancer patients. Pretreatment of murine tumors with collagenases increased drug uptake and diffusion 2-10-fold. This modest improvement resulted in decreased tumor growth, but the benefits of collagenase treatment are confounded by risks of toxicity from collagen breakdown in healthy tissues. In this review, we evaluate the published in vitro and in vivo benefits and limitations of collagenase treatment to improve drug delivery.

Focus-based filtering + clustering technique for power-law networks with small world phenomenon

NASA Astrophysics Data System (ADS)

Boutin, François; Thièvre, Jérôme; Hascoët, Mountaz

2006-01-01

Realistic interaction networks usually present two main properties: a power-law degree distribution and a small world behavior. Few nodes are linked to many nodes and adjacent nodes are likely to share common neighbors. Moreover, graph structure usually presents a dense core that is difficult to explore with classical filtering and clustering techniques. In this paper, we propose a new filtering technique accounting for a user-focus. This technique extracts a tree-like graph with also power-law degree distribution and small world behavior. Resulting structure is easily drawn with classical force-directed drawing algorithms. It is also quickly clustered and displayed into a multi-level silhouette tree (MuSi-Tree) from any user-focus. We built a new graph filtering + clustering + drawing API and report a case study.

Endemic chronic kidney disease of unknown etiology in Sri Lanka: Correlation of pathology with clinical stages.

PubMed

Wijetunge, S; Ratnatunga, N V I; Abeysekera, T D J; Wazil, A W M; Selvarajah, M

2015-01-01

Chronic kidney disease of unknown etiology (CKDU) is endemic among the rural farming communities in several localities in and around the North Central region of Sri Lanka. This is an interstitial type renal disease and typically has an insidious onset and slow progression. This study was conducted to identify the pathological features in the different clinical stages of CKDU. This is a retrospective study of 251 renal biopsies identified to have a primary interstitial disease from regions endemic for CKDU. Pathological features were assessed and graded in relation to the clinical stage. The mean age of those affected by endemic CKDU was 37.3 ± 12.5 years and the male to female ratio was 3.3:1. The predominant feature of stage I disease was mild and moderate interstitial fibrosis; most did not have interstitial inflammation. The typical stage II disease had moderate interstitial fibrosis with or without mild interstitial inflammation. Stage III disease had moderate and severe interstitial fibrosis, moderate interstitial inflammation, tubular atrophy and some glomerulosclerosis. Stage IV disease typically had severe interstitial fibrosis and inflammation, tubular atrophy and glomerulosclerosis. The mean age of patients with stage I disease (27 ± 10.8 years) was significantly lower than those of the other stages. About 79.2%, 55%, 49.1% and 50% in stage I, II, III and IV disease respectively were asymptomatic at the time of biopsy.

Intravesical NGF Antisense Therapy Using Lipid Nanoparticle for Interstitial Cystitis

DTIC Science & Technology

2015-10-01

intravesical botulinum toxin type A injec- tions plus hydrodistention with hydrodis- tention alone for the treatment of refractory interstitial cystitis/ painful ...SUPPLEMENTARY NOTES 14. ABSTRACT Interstitial cystitis/bladder pain syndrome (IC/BPS) is a debilitating disorder characterized by persistent pelvic pain ...from an animal efficacy experiment conducted during the previous period. The project is ongoing. 15. SUBJECT TERMS Interstitial cystitis/ painful

In vivo interstitial glucose characterization and monitoring in the skin by ATR-FTIR spectroscopy

NASA Astrophysics Data System (ADS)

Skrebova Eikje, Natalja

2011-03-01

Successful development of real-time non-invasive glucose monitoring would represent a major advancement not only in the treatment and management of patients with diabetes mellitus and carbohydrate metabolism disorders, but also for understanding in those biochemical, metabolic and (patho-)physiological processes of glucose at the molecular level in vivo. Here, ATR-FTIR spectroscopy technique has been challenged not only for in vivo measurement of interstitial glucose levels, but also for their non-invasive molecular qualitative and quantitative comparative characterization in the skin tissue. The results, based on calculated mean values of determined 5 glucose-specific peaks in the glucose-related 1000-1160 cm-1 region, showed intra- and inter-subject differences in interstitial glucose activity levels with their changes at different times and doses of OGTT, while raising questions about the relationships between interstitial and blood glucose levels. In conclusion, the introduction of ATR-FTIR spectroscopy technique has opened up an access to the interstitial fluid space in the skin tissue for interstitial glucose characterization and monitoring in vivo. Though interstitial versus blood glucose monitoring has different characteristics, it can be argued that accurate and precise measurements of interstitial glucose levels may be more important clinically.

New insights into canted spiro carbon interstitial in graphite

NASA Astrophysics Data System (ADS)

EL-Barbary, A. A.

2017-12-01

The self-interstitial carbon is the key to radiation damage in graphite moderator nuclear reactor, so an understanding of its behavior is essential for plant safety and maximized reactor lifetime. The density functional theory is applied on four different graphite unit cells, starting from of 64 carbon atoms up to 256 carbon atoms, using AIMPRO code to obtain the energetic, athermal and mechanical properties of carbon interstitial in graphite. This study presents first principles calculations of the energy of formation that prove its high barrier to athermal diffusion (1.1 eV) and the consequent large critical shear stress (39 eV-50 eV) necessary to shear graphite planes in its presence. Also, for the first time, the gamma surface of graphite in two dimensions is calculated and found to yield the critical shear stress for perfect graphite. Finally, in contrast to the extensive literature describing the interstitial of carbon in graphite as spiro interstitial, in this work the ground state of interstitial carbon is found to be canted spiro interstitial.

Stability and minimum size of colloidal clusters on a liquid-air interface.

PubMed

Pergamenshchik, V M

2012-02-01

A vertical force applied to each of two colloids, trapped at a liquid-air interface, induces their logarithmic pairwise attraction. I recently showed [Phys. Rev. E 79, 011407 (2009)] that in clusters of size R much larger than the capillary length λ, the attraction changes to that of a power law and is much stronger due to a many-body effect, and I derived two equations that describe the equilibrium coarse-grained meniscus profile and colloid density in such clusters. In this paper, this theory is shown also to describe small clusters with R≪ λ provided the number N of colloids therein is sufficiently large. An analytical solution for a small circular cluster with an arbitrary short-range power-law pairwise repulsion is found. The energy of a cluster is obtained as a function of its radius R and colloid number N. As in large clusters, the attraction force and energy universally scale with the distance L between colloids as L(-3) and L(-2), respectively, for any repulsion forces. The states of an equilibrium cluster, predicted by the theory, are shown to be stable with respect to small perturbations of the meniscus profile and colloid density. The minimum number of colloids in a circular cluster, which sustains the thermal motion, is estimated. For standard parameters, it can be very modest, e.g., in the range 20-200, which is in line with experimental findings on reversible clusterization on a liquid-air interface. © 2012 American Physical Society

Small traveling clusters in attractive and repulsive Hamiltonian mean-field models.

PubMed

Barré, Julien; Yamaguchi, Yoshiyuki Y

2009-03-01

Long-lasting small traveling clusters are studied in the Hamiltonian mean-field model by comparing between attractive and repulsive interactions. Nonlinear Landau damping theory predicts that a Gaussian momentum distribution on a spatially homogeneous background permits the existence of traveling clusters in the repulsive case, as in plasma systems, but not in the attractive case. Nevertheless, extending the analysis to a two-parameter family of momentum distributions of Fermi-Dirac type, we theoretically predict the existence of traveling clusters in the attractive case; these findings are confirmed by direct N -body numerical simulations. The parameter region with the traveling clusters is much reduced in the attractive case with respect to the repulsive case.

Clustering of water molecules in ultramicroporous carbon: In-situ small-angle neutron scattering

DOE PAGES

Bahadur, Jitendra; Contescu, Cristian I.; Rai, Durgesh K.; ...

2016-10-19

The adsorption of water is central to most of the applications of microporous carbon as adsorbent material. We report early kinetics of water adsorption in the microporous carbon using in-situ small-angle neutron scattering. It is observed that adsorption of water occurs via cluster formation of molecules. Interestingly, the cluster size remains constant throughout the adsorption process whereas number density of clusters increases with time. The role of surface chemistry of microporous carbon on the early kinetics of adsorption process was also investigated. Lastly, the present study provides direct experimental evidence for cluster assisted adsorption of water molecules in microporous carbonmore » (Do-Do model).« less

Theoretical and experimental insights into the origin of the catalytic activity of subnanometric gold clusters: attempts to predict reactivity with clusters and nanoparticles of gold.

PubMed

Boronat, Mercedes; Leyva-Pérez, Antonio; Corma, Avelino

2014-03-18

Particle size is one of the key parameters determining the unexpected catalytic activity of gold, with reactivity improving as the particle gets smaller. While this is valid in the 1-5 nm range, chemists are now investigating the influence of particle size in the subnanometer regime. This is due to recent advances in both characterization techniques and synthetic routes capable of stabilizing these size-controlled gold clusters. Researchers reported in early studies that small clusters or aggregates of a few atoms can be extremely active in some reactions, while 1-2 nm nanoparticles are catalytically more efficient for other reactions. Furthermore, the possibility that small gold clusters generated in situ from gold salts or complexes could be the real active species in homogeneous gold-catalyzed organic reactions should be considered. In this Account, we address two questions. First, what is the origin of the enhanced reactivity of gold clusters on the subnanometer scale? And second, how can we predict the reactions where small clusters should work better than larger nanoparticles? Both geometric factors and electronic or quantum size effects become important in the subnanometer regime. Geometric reasons play a key role in hydrogenation reactions, where only accessible low coordinated neutral Au atoms are needed to dissociate H2. The quantum size effects of gold clusters are important as well, as clusters formed by only a few atoms have discrete molecule-like electronic states and their chemical reactivity is related to interactions between the cluster's frontier molecular orbitals and those of the reactant molecules. From first principles calculations, we predict an enhanced reactivity of small planar clusters for reactions involving activation of CC multiple bonds in alkenes and alkynes through Lewis acid-base interactions, and a better catalytic performance of 3D gold nanoparticles in redox reactions involving bond dissociation by oxidative addition and new bond formation by reductive elimination. In oxidation reactions with molecular O2, initial dissociation of O2 into basic oxygen atoms would be more effectively catalyzed by gold nanoparticles of ∼1 nm diameter. In contrast, small planar clusters should be more active for reactions following a radical pathway involving peroxo or hydroperoxo intermediates. We have experimentally confirmed these predictions for a series of Lewis acid and oxidation reactions catalyzed by gold clusters and nanoparticles either in solution or supported on solid carriers.

Cluster Free Energies from Simple Simulations of Small Numbers of Aggregants: Nucleation of Liquid MTBE from Vapor and Aqueous Phases.

PubMed

Patel, Lara A; Kindt, James T

2017-03-14

We introduce a global fitting analysis method to obtain free energies of association of noncovalent molecular clusters using equilibrated cluster size distributions from unbiased constant-temperature molecular dynamics (MD) simulations. Because the systems simulated are small enough that the law of mass action does not describe the aggregation statistics, the method relies on iteratively determining a set of cluster free energies that, using appropriately weighted sums over all possible partitions of N monomers into clusters, produces the best-fit size distribution. The quality of these fits can be used as an objective measure of self-consistency to optimize the cutoff distance that determines how clusters are defined. To showcase the method, we have simulated a united-atom model of methyl tert-butyl ether (MTBE) in the vapor phase and in explicit water solution over a range of system sizes (up to 95 MTBE in the vapor phase and 60 MTBE in the aqueous phase) and concentrations at 273 K. The resulting size-dependent cluster free energy functions follow a form derived from classical nucleation theory (CNT) quite well over the full range of cluster sizes, although deviations are more pronounced for small cluster sizes. The CNT fit to cluster free energies yielded surface tensions that were in both cases lower than those for the simulated planar interfaces. We use a simple model to derive a condition for minimizing non-ideal effects on cluster size distributions and show that the cutoff distance that yields the best global fit is consistent with this condition.

Delivery of Iron-Sulfur Clusters to the Hydrogen-Oxidizing [NiFe]-Hydrogenases in Escherichia coli Requires the A-Type Carrier Proteins ErpA and IscA

PubMed Central

Pinske, Constanze; Sawers, R. Gary

2012-01-01

During anaerobic growth Escherichia coli synthesizes two membrane-associated hydrogen-oxidizing [NiFe]-hydrogenases, termed hydrogenase 1 and hydrogenase 2. Each enzyme comprises a catalytic subunit containing the [NiFe] cofactor, an electron-transferring small subunit with a particular complement of [Fe-S] (iron-sulfur) clusters and a membrane-anchor subunit. How the [Fe-S] clusters are delivered to the small subunit of these enzymes is unclear. A-type carrier (ATC) proteins of the Isc (iron-sulfur-cluster) and Suf (sulfur mobilization) [Fe-S] cluster biogenesis pathways are proposed to traffic pre-formed [Fe-S] clusters to apoprotein targets. Mutants that could not synthesize SufA had active hydrogenase 1 and hydrogenase 2 enzymes, thus demonstrating that the Suf machinery is not required for hydrogenase maturation. In contrast, mutants devoid of the IscA, ErpA or IscU proteins of the Isc machinery had no detectable hydrogenase 1 or 2 activities. Lack of activity of both enzymes correlated with the absence of the respective [Fe-S]-cluster-containing small subunit, which was apparently rapidly degraded. During biosynthesis the hydrogenase large subunits receive their [NiFe] cofactor from the Hyp maturation machinery. Subsequent to cofactor insertion a specific C-terminal processing step occurs before association of the large subunit with the small subunit. This processing step is independent of small subunit maturation. Using western blotting experiments it could be shown that although the amount of each hydrogenase large subunit was strongly reduced in the iscA and erpA mutants, some maturation of the large subunit still occurred. Moreover, in contrast to the situation in Isc-proficient strains, these processed large subunits were not membrane-associated. Taken together, our findings demonstrate that both IscA and ErpA are required for [Fe-S] cluster delivery to the small subunits of the hydrogen-oxidizing hydrogenases; however, delivery of the Fe atom to the active site might have different requirements. PMID:22363723

Barrier-free subsurface incorporation of 3 d metal atoms into Bi(111) films

DOE PAGES

Klein, C.; Vollmers, N. J.; Gerstmann, U.; ...

2015-05-27

By combining scanning tunneling microscopy with density functional theory it is shown that the Bi(111) surface provides a well-defined incorporation site in the first bilayer that traps highly coordinating atoms such as transition metals (TMs) or noble metals. All deposited atoms assume exactly the same specific sevenfold coordinated subsurface interstitial site while the surface topography remains nearly unchanged. Notably, 3 d TMs show a barrier-free incorporation. The observed surface modification by barrier-free subsorption helps to suppress aggregation in clusters. Thus, it allows a tuning of the electronic properties not only for the pure Bi(111) surface, but may also be observedmore » for topological insulators formed by substrate-stabilized Bi bilayers.« less

Magnetic nanostructures.

PubMed

Bennemann, K

2010-06-23

Characteristic results of magnetism in small particles, thin films and tunnel junctions are presented. As a consequence of the reduced atomic coordination in small clusters and thin films the electronic states and density of states are modified. Thus, magnetic moments and magnetization are affected. Generally, in clusters and thin films magnetic anisotropy plays a special role. In tunnel junctions the interplay of magnetism, spin currents and superconductivity are of particular interest. In ring-like mesoscopic systems Aharonov-Bohm-induced currents are studied. Results are given for single transition metal clusters, cluster ensembles, thin films, mesoscopic structures and tunnel systems. © 2010 IOP Publishing Ltd

Analysis of radiation-induced small Cu particle cluster formation in aqueous CuCl2

USGS Publications Warehouse

Jayanetti, Sumedha; Mayanovic, Robert A.; Anderson, Alan J.; Bassett, William A.; Chou, I.-Ming

2001-01-01

Radition-induced small Cu particle cluster formation in aqueous CuCl2 was analyzed. It was noticed that nearest neighbor distance increased with the increase in the time of irradiation. This showed that the clusters approached the lattice dimension of bulk copper. As the average cluster size approached its bulk dimensions, an increase in the nearest neighbor coordination number was found with the decrease in the surface to volume ratio. Radiolysis of water by incident x-ray beam led to the reduction of copper ions in the solution to themetallic state.

Monogenetic Volcano Clusters within the wider Michoacán-Guanajuato Volcanic Field (México) and their Significance

NASA Astrophysics Data System (ADS)

Siebe, C.

2017-12-01

The Trans-Mexican Volcanic Belt, one of the most complex and active continental arcs worldwide, displays several volcanic fields dominated by monogenetic volcanoes. Of these, the Plio-Quaternary Michoacán-Guanajuato Volcanic Field (MGVF) situated in central Mexico, is the largest monogenetic volcanic field in the world and includes more than 1000 scoria cones and associated lava flows and about 400 medium-sized volcanoes (Mexican shields). The smaller monogenetic vents occur either isolated or form small clusters within the wider MGVF. The recent identification of small clusters comprising several monogenetic volcanoes that erupted in a sequence of geologically short time intervals (hundreds to few thousands of years) in small areas within the much wider MGVF opens several questions in regard to future volcanic hazard assessments in this region: Are the youngest (Holocene) clusters still "active" and is a new eruption likely to occur within their surroundings? How long are such clusters "active"? Will the next monogenetic eruption in the MGVF be a single short-lived isolated eruption, or the beginning of a cluster? Furthermore, is it possible that the historic eruptions of Jorullo (1759) and Paricutin (1943) represent each the beginning of a cluster and should a new eruption in their proximity be expected in the future? In order to address these questions, two Holocene clusters, namely Tacámbaro and Malpaís de Zacapu are currently under study and preliminary results will be presented. Each comprises four monogenetic vents that erupted in a sequence of geologically short time intervals (hundreds to few thousands of years) within a small area (few tens of km2) Geologic mapping, geochemical analyses, radiometric dating, and paleomagnetic studies will help to establish the sequence of eruption of the different vents, and shed more light on the conditions that allow several magma sources to be formed and then tapped in close temporal and spatial proximity to each other and produce such small "flare-ups".

Lung volumes and emphysema in smokers with interstitial lung abnormalities.

PubMed

Washko, George R; Hunninghake, Gary M; Fernandez, Isis E; Nishino, Mizuki; Okajima, Yuka; Yamashiro, Tsuneo; Ross, James C; Estépar, Raúl San José; Lynch, David A; Brehm, John M; Andriole, Katherine P; Diaz, Alejandro A; Khorasani, Ramin; D'Aco, Katherine; Sciurba, Frank C; Silverman, Edwin K; Hatabu, Hiroto; Rosas, Ivan O

2011-03-10

Cigarette smoking is associated with emphysema and radiographic interstitial lung abnormalities. The degree to which interstitial lung abnormalities are associated with reduced total lung capacity and the extent of emphysema is not known. We looked for interstitial lung abnormalities in 2416 (96%) of 2508 high-resolution computed tomographic (HRCT) scans of the lung obtained from a cohort of smokers. We used linear and logistic regression to evaluate the associations between interstitial lung abnormalities and HRCT measurements of total lung capacity and emphysema. Interstitial lung abnormalities were present in 194 (8%) of the 2416 HRCT scans evaluated. In statistical models adjusting for relevant covariates, interstitial lung abnormalities were associated with reduced total lung capacity (-0.444 liters; 95% confidence interval [CI], -0.596 to -0.292; P<0.001) and a lower percentage of emphysema defined by lung-attenuation thresholds of -950 Hounsfield units (-3%; 95% CI, -4 to -2; P<0.001) and -910 Hounsfield units (-10%; 95% CI, -12 to -8; P<0.001). As compared with participants without interstitial lung abnormalities, those with abnormalities were more likely to have a restrictive lung deficit (total lung capacity <80% of the predicted value; odds ratio, 2.3; 95% CI, 1.4 to 3.7; P<0.001) and were less likely to meet the diagnostic criteria for chronic obstructive pulmonary disease (COPD) (odds ratio, 0.53; 95% CI, 0.37 to 0.76; P<0.001). The effect of interstitial lung abnormalities on total lung capacity and emphysema was dependent on COPD status (P<0.02 for the interactions). Interstitial lung abnormalities were positively associated with both greater exposure to tobacco smoke and current smoking. In smokers, interstitial lung abnormalities--which were present on about 1 of every 12 HRCT scans--were associated with reduced total lung capacity and a lesser amount of emphysema. (Funded by the National Institutes of Health and the Parker B. Francis Foundation; ClinicalTrials.gov number, NCT00608764.).

Interstitial Lung Diseases

MedlinePlus

Interstitial lung disease is the name for a large group of diseases that inflame or scar the lungs. The inflammation and ... is responsible for some types of interstitial lung diseases. Specific types include Black lung disease among coal ...

Cluster size dependence of high-order harmonic generation

NASA Astrophysics Data System (ADS)

Tao, Y.; Hagmeijer, R.; Bastiaens, H. M. J.; Goh, S. J.; van der Slot, P. J. M.; Biedron, S. G.; Milton, S. V.; Boller, K.-J.

2017-08-01

We investigate high-order harmonic generation (HHG) from noble gas clusters in a supersonic gas jet. To identify the contribution of harmonic generation from clusters versus that from gas monomers, we measure the high-order harmonic output over a broad range of the total atomic number density in the jet (from 3×1016 to 3 × 1018 {{cm}}-3) at two different reservoir temperatures (303 and 363 K). For the first time in the evaluation of the harmonic yield in such measurements, the variation of the liquid mass fraction, g, versus pressure and temperature is taken into consideration, which we determine, reliably and consistently, to be below 20% within our range of experimental parameters. By comparing the measured harmonic yield from a thin jet with the calculated corresponding yield from monomers alone, we find an increased emission of the harmonics when the average cluster size is less than 3000. Using g, under the assumption that the emission from monomers and clusters add up coherently, we calculate the ratio of the average single-atom response of an atom within a cluster to that of a monomer and find an enhancement of around 100 for very small average cluster size (∼200). We do not find any dependence of the cut-off frequency on the composition of the cluster jet. This implies that HHG in clusters is based on electrons that return to their parent ions and not to neighboring ions in the cluster. To fully employ the enhanced average single-atom response found for small average cluster sizes (∼200), the nozzle producing the cluster jet must provide a large liquid mass fraction at these small cluster sizes for increasing the harmonic yield. Moreover, cluster jets may allow for quasi-phase matching, as the higher mass of clusters allows for a higher density contrast in spatially structuring the nonlinear medium.

Endemic chronic kidney disease of unknown etiology in Sri Lanka: Correlation of pathology with clinical stages

PubMed Central

Wijetunge, S.; Ratnatunga, N. V. I.; Abeysekera, T. D. J.; Wazil, A. W. M.; Selvarajah, M.

2015-01-01

Chronic kidney disease of unknown etiology (CKDU) is endemic among the rural farming communities in several localities in and around the North Central region of Sri Lanka. This is an interstitial type renal disease and typically has an insidious onset and slow progression. This study was conducted to identify the pathological features in the different clinical stages of CKDU. This is a retrospective study of 251 renal biopsies identified to have a primary interstitial disease from regions endemic for CKDU. Pathological features were assessed and graded in relation to the clinical stage. The mean age of those affected by endemic CKDU was 37.3 ± 12.5 years and the male to female ratio was 3.3:1. The predominant feature of stage I disease was mild and moderate interstitial fibrosis; most did not have interstitial inflammation. The typical stage II disease had moderate interstitial fibrosis with or without mild interstitial inflammation. Stage III disease had moderate and severe interstitial fibrosis, moderate interstitial inflammation, tubular atrophy and some glomerulosclerosis. Stage IV disease typically had severe interstitial fibrosis and inflammation, tubular atrophy and glomerulosclerosis. The mean age of patients with stage I disease (27 ± 10.8 years) was significantly lower than those of the other stages. About 79.2%, 55%, 49.1% and 50% in stage I, II, III and IV disease respectively were asymptomatic at the time of biopsy. PMID:26628792

Computed tomographic features of idiopathic fibrosing interstitial pneumonia: comparison with pulmonary fibrosis related to collagen vascular disease.

PubMed

Hwang, Jeong-Hwa; Misumi, Shigeki; Sahin, Hakan; Brown, Kevin K; Newell, John D; Lynch, David A

2009-01-01

To compare the computed tomographic (CT) features of idiopathic fibrosing interstitial pneumonia with those of pulmonary fibrosis related to collagen vascular disease (CVD). We reviewed the CT scans of 177 patients with diffuse interstitial pulmonary fibrosis, of which 97 had idiopathic fibrosing interstitial pneumonia and 80 had CVD. The CT images were systematically scored for the presence and extent of pulmonary and extrapulmonary abnormalities. Computed tomographic diagnosis of usual interstitial pneumonia (UIP) or nonspecific interstitial pneumonia (NSIP) was assigned. A CT pattern of UIP was identified in 59 (60.8%) of patients with idiopathic fibrosing interstitial pneumonia compared with 15 (18.7%) of those patients with CVD; conversely, the CT diagnosis of NSIP was made in 51 (64%) of patients with CVD compared with 36 (37%) of patients with idiopathic disease (P < 0.01). In 113 patients who had lung biopsy, the CT diagnoses of UIP and NSIP were concordant with the histologic diagnoses in 36 of 50 patients and 34 of 41 patients, respectively. Pleural effusions, esophageal dilation, and pericardial abnormalities were more frequent in patients with CVD than in patients with idiopathic fibrosing interstitial pneumonia. Compared with patients with CVD, those patients with an idiopathic fibrosing interstitial pneumonia showed a higher prevalence of a UIP pattern and lower prevalence of an NSIP pattern as determined by CT. Identification of coexisting extrapulmonary abnormalities on CT can support a diagnosis of CVD.

[Convergence nystagmus and vertical gaze palsy of vascular origin].

PubMed

Jouvent, E; Benisty, S; Fenelon, G; Créange, A; Pierrot-Deseilligny, C

2005-05-01

A case of convergence-retraction nystagmus with upward vertical gaze paralysis and skew deviation (right hypotropia), without any other neurological signs, is reported. The probably vascular lesion was located at the mesodiencephalic junction, lying between the right border of the posterior commissure, the right interstitial nucleus of Cajal and the periaqueductal grey matter, accounting for the three ocular motor signs. The particular interest of this case is due to the relative smallness of the lesion.

Osimertinib-induced interstitial lung disease in a patient with non-small cell lung cancer pretreated with nivolumab: A case report.

PubMed

Takakuwa, Osamu; Oguri, Tetsuya; Uemura, Takehiro; Sone, Kazuki; Fukuda, Satoshi; Okayama, Minami; Kanemitsu, Yoshihiro; Ohkubo, Hirotsugu; Takemura, Masaya; Ito, Yutaka; Maeno, Ken; Niimi, Akio

2017-09-01

Osimertinib (AZD9291) is a third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor approved for EGFR-T790M-positive non-small cell lung cancer. A high incidence of interstitial lung disease (ILD) during combination treatment with osimertinib and anti-programmed cell death-ligand 1 (PD-L1) inhibitor has been reported. The current study presents a case of ILD development during osimertinib treatment following nivolumab (an anti-PD-1 antibody) treatment. The 59-year-old female was diagnosed with stage IV lung adenocarcinoma harboring a deletion in exon 19 of the EGFR gene. Following nivolumab as a sixth-line treatment, an EGFR-T790M-encoding mutation in EGFR exon 20 was identified by re-biopsy. Osimertinib was therefore initiated as a seventh-line treatment. A partial response was subsequently noted; however, 63 days after initiation of the treatment the patient presented with dyspnea with decreased oxygenation in the absence of fever and sputum. A computed tomography scan revealed the emergence of ground-glass opacities with bronchiectasis in both lungs, and a diagnosis of ILD due to osimertinib was made. Following steroid pulse therapy with discontinuation of osimertinib, the patient's chest findings and respiratory condition improved. Therefore, it is considered that anti-PD-1 therapies may be associated with a risk of ILD during subsequent osimertinib treatment.

Carbachol regulates pacemaker activities in cultured interstitial cells of Cajal from the mouse small intestine.

PubMed

So, Keum Young; Kim, Sang Hun; Sohn, Hong Moon; Choi, Soo Jin; Parajuli, Shankar Prasad; Choi, Seok; Yeum, Cheol Ho; Yoon, Pyung Jin; Jun, Jae Yeoul

2009-05-31

We studied the effect of carbachol on pacemaker currents in cultured interstitial cells of Cajal (ICC) from the mouse small intestine by muscarinic stimulation using a whole cell patch clamp technique and Ca2+-imaging. ICC generated periodic pacemaker potentials in the current-clamp mode and generated spontaneous inward pacemaker currents at a holding potential of-70 mV. Exposure to carbachol depolarized the membrane and produced tonic inward pacemaker currents with a decrease in the frequency and amplitude of the pacemaker currents. The effects of carbachol were blocked by 1-dimethyl-4-diphenylacetoxypiperidinium, a muscarinic M(3) receptor antagonist, but not by methotramine, a muscarinic M(2) receptor antagonist. Intracellular GDP-beta-S suppressed the carbachol-induced effects. Carbachol-induced effects were blocked by external Na+-free solution and by flufenamic acid, a non-selective cation channel blocker, and in the presence of thapsigargin, a Ca2+-ATPase inhibitor in the endoplasmic reticulum. However, carbachol still produced tonic inward pacemaker currents with the removal of external Ca2+. In recording of intracellular Ca2+ concentrations using fluo 3-AM dye, carbachol increased intracellular Ca2+ concentrations with increasing of Ca2+ oscillations. These results suggest that carbachol modulates the pacemaker activity of ICC through the activation of non-selective cation channels via muscarinic M(3) receptors by a G-protein dependent intracellular Ca2+ release mechanism.

Tantalum induced butterfly-like clusters on Si (111)-7 × 7 surface: STM/STS study at low coverage

NASA Astrophysics Data System (ADS)

Shukrynau, Pavel; Mutombo, Pingo; Švec, Martin; Hietschold, Michael; Cháb, Vladimír

2012-02-01

The adsorption of the small amounts of tantalum on Si (111)-7 × 7 reconstructed surface is investigated systematically using scanning tunneling microscopy and tunneling spectroscopy combined with first-principles density functional theory calculations. We find out that the moderate annealing of the Ta covered surface results in the formation of clusters of the butterfly-like shape. The clusters are sporadically distributed over the surface and their density is metal coverage dependent. Filled and empty state STM images of the clusters differ strongly suggesting the existence of covalent bonds within the cluster. Tunneling spectroscopy measurements reveal small energy gap, showing semiconductor-like behavior of the constituent atoms. The cluster model based on experimental images and theoretical calculations has been proposed and discussed. Presented results show that Ta joins the family of adsorbates, that are known to form magic clusters on Si (111)-7 × 7, but its magic cluster has the structural and electronic properties that are different from those reported before.

Induced Autologous Stem Cell Transplantation for Treatment of Rabbit Renal Interstitial Fibrosis

PubMed Central

Ruan, Guang-Ping; Xu, Fan; Li, Zi-An; Zhu, Guang-Xu; Pang, Rong-Qing; Wang, Jin-Xiang; Cai, Xue-Min; He, Jie; Yao, Xiang; Ruan, Guang-Hong; Xu, Xin-Ming; Pan, Xing-Hua

2013-01-01

Introduction Renal interstitial fibrosis (RIF) is a significant cause of end-stage renal failure. The goal of this study was to characterize the distribution of transplanted induced autologous stem cells in a rabbit model of renal interstitial fibrosis and evaluate its therapeutic efficacy for treatment of renal interstitial fibrosis. Methods A rabbit model of renal interstitial fibrosis was established. Autologous fibroblasts were cultured, induced and labeled with green fluorescent protein (GFP). These labeled stem cells were transplanted into the renal artery of model animals at 8 weeks. Results Eight weeks following transplantation of induced autologous stem cells, significant reductions (P < 0.05) were observed in serum creatinine (SCr) (14.8 ± 1.9 mmol/L to 10.1 ± 2.1 mmol/L) and blood urea nitrogen (BUN) (119 ± 22 µmol/L to 97 ± 13 µmol/L), indicating improvement in renal function. Conclusions We successfully established a rabbit model of renal interstitial fibrosis and demonstrated that transplantation of induced autologous stem cells can repair kidney damage within 8 weeks. The repair occurred by both inhibition of further development of renal interstitial fibrosis and partial reversal of pre-existing renal interstitial fibrosis. These beneficial effects lead to the development of normal tissue structure and improved renal function. PMID:24367598

Carbon, oxygen and their interaction with intrinsic point defects in solar silicon ribbon material: A speculative approach

NASA Technical Reports Server (NTRS)

Goesele, U.; Ast, D. G.

1983-01-01

Some background information on intrinsic point defects is provided and on carbon and oxygen in silicon in so far as it may be relevant for the efficiency of solar cells fabricated from EFG ribbon material. The co-precipitation of carbon and oxygen and especially of carbon and silicon self interstitials are discussed. A simple model for the electrical activity of carbon-self-interstitial agglomerates is presented. The self-interstitial content of these agglomerates is assumed to determine their electrical activity and that both compressive stresses (high self-interstitial content) and tensile stresses (low self-interstitial content) give rise to electrical activity of the agglomerates. The self-interstitial content of these carbon-related agglomerates may be reduced by an appropriate high temperature treatment and enhanced by a supersaturation of self-interstitials generated during formation of the p-n junction of solar cells. Oxygen present in supersaturation in carbon-rich silicon may be induced to form SiO, precipitates by self-interstitials generated during phosphorus diffusion. It is proposed that the SiO2-Si interface of the precipates gives rise to a continuum of donor stables and that these interface states are responsible for at least part of the light inhancement effects observed in oxygen containing EFG silicon after phosphorus diffusion.

A Case of Clinically Amyopathic Dermatomyositis with Interstitial Pneumonia that Was Successfully Treated with Plasma Exchange.

PubMed

Yagishita, Mizuki; Kondo, Yuya; Terasaki, Toshihiko; Terasaki, Mayu; Shimizu, Masaru; Honda, Fumika; Oyama, Ayako; Takahashi, Hiroyuki; Yokosawa, Masahiro; Asashima, Hiromitsu; Hagiwara, Shinya; Tsuboi, Hiroto; Matsumoto, Isao; Sumida, Takayuki

2018-02-28

Patients with clinically amyopathic dermatomyositis (CADM), a subset of dermatomyositis characterized by a lack of muscle involvement, frequently develop rapidly progressive and treatment-resistant interstitial lung disease. We report the case of a 49-year-old man who was diagnosed with CADM. He developed interstitial pneumonia, which did not respond to combination therapy with methylprednisolone pulse therapy, cyclophosphamide, and cyclosporine. We therefore attempted plasma exchange. After 7 courses of therapeutic plasma exchange, the interstitial pneumonia gradually improved. This case suggests that plasma exchange might be an effective therapeutic option for patients with progressive interstitial lung disease in steroid- and immunosuppressive therapy-refractive CADM.

Molecular dynamics growth modeling of InAs1-xSbx-based type-II superlattice

NASA Astrophysics Data System (ADS)

Ciani, Anthony J.; Grein, Christoph H.; Irick, Barry; Miao, Maosheng; Kioussis, Nicholas

2017-09-01

Type-II strained-layer superlattices (T2SL) based on InAs1-xSbx are a promising photovoltaic detector material technology for thermal imaging; however, Shockley-Read-Hall recombination and generation rates are still too high for thermal imagers based on InAs1-xSbx T2SL to reach their ideal performance. Molecular dynamics simulations using the Stillinger-Weber (SW) empirical potentials are a useful tool to study the growth of tetrahedral coordinated crystals and the nonequilibrium formation of defects within them, including the long-range effects of strain. SW potentials for the possible atomic interactions among {Ga, In, As, Sb} were developed by fitting to ab initio calculations of elastically distorted zinc blende and diamond unit cells. The SW potentials were tested against experimental observations of molecular beam epitaxial (MBE) growth and then used to simulate the MBE growth of InAs/InAs0.5Sb0.5 T2SL on GaSb substrates over a range of processes parameters. The simulations showed and helped to explain Sb cross-incorporation into the InAs T2SL layers, Sb segregation within the InAsSb layers, and identified medium-range defect clusters involving interstitials and their induction of interstitial-vacancy pairs. Defect formation was also found to be affected by growth temperature and flux stoichiometry.

A nonlinear model for myogenic regulation of blood flow to bone: equilibrium states and stability characteristics.

PubMed

Harrigan, T P

1996-01-01

A simple compartmental model for myogenic regulation of interstitial pressure in bone is developed, and the interaction between changes in interstitial pressure and changes in arterial and venous resistance is studied. The arterial resistance is modeled by a myogenic model that depends on transmural pressure, and the venous resistance is modeled by using a vascular waterfall. Two series capacitances model blood storage in the vascular system and interstitial fluid storage in the extravascular space. The static results mimic the observed effect that vasodilators work less well in bone than do vasoconstrictors. The static results also show that the model gives constant flow rates over a limited range of arterial pressure. The dynamic model shows unstable behavior at small values of bony capacitance and at high enough myogenic gain. At low myogenic gain, only a single equilibrium state is present, but a high enough myogenic gain, two new equilibrium states appear. At additional increases in gain, one of the two new states merges with and then separates from the original state, and the original state becomes a saddle point. The appearance of the new states and the transition of the original state to a saddle point do not depend on the bony capacitance, and these results are relevant to general fluid compartments. Numerical integration of the rate equations confirms the stability calculations and shows limit cycling behavior in several situations. The relevance of this model to circulation in bone and to other compartments is discussed.

Molecular dynamic simulation study of plasma etching L10 FePt media in embedded mask patterning (EMP) process

NASA Astrophysics Data System (ADS)

Zhu, Jianxin; Quarterman, P.; Wang, Jian-Ping

2017-05-01

Plasma etching process of single-crystal L10-FePt media [H. Wang et al., Appl. Phys. Lett. 102(5) (2013)] is studied using molecular dynamic simulation. Embedded-Atom Method [M. S. Daw and M. I. Baskes, Phy. Rev. B 29, 6443 (1984); X. W. Zhou, R. A. Johnson and H. N. G. Wadley, Phy. Rev. B 69, 144113 (2004)] is used to calculate the interatomic potential within atoms in FePt alloy, and ZBL potential [J.F. Ziegler, J. P. Biersack and U. Littmark, "The Stopping and Range of Ions in Matter," Volume 1, Pergamon,1985] in comparison with conventional Lennard-Jones "12-6" potential is applied to interactions between etching gas ions and metal atoms. It is shown the post-etch structure defects can include amorphized surface layer and lattice interstitial point defects that caused by etchant ions passed through the surface layer. We show that the amorphized or damaged FePt lattice surface layer (or "magnetic dead-layer") thickness after etching increases with ion energy for Ar ion impacts, but significantly small for He ions at up to 250eV ion energy. However, we showed that He sputtering creates more interstitial defects at lower energy levels and defects are deeper below the surface compared to Ar sputtering. We also calculate the interstitial defect level and depth as dependence on ion energy for both Ar and He ions. Media magnetic property loss due to these defects is also discussed.

Modeling of heat transfer in a vascular tissue-like medium during an interstitial hyperthermia process.

PubMed

Hassanpour, Saeid; Saboonchi, Ahmad

2016-12-01

This paper aims to evaluate the role of small vessels in heat transfer mechanisms of a tissue-like medium during local intensive heating processes, for example, an interstitial hyperthermia treatment. To this purpose, a cylindrical tissue with two co- and counter-current vascular networks and a central heat source is introduced. Next, the energy equations of tissue, supply fluid (arterial blood), and return fluid (venous blood) are derived using porous media approach. Then, a 2D computer code is developed to predict the temperature of blood (fluid phase) and tissue (solid phase) by conventional volume averaging method and a more realistic solution method. In latter method, despite the volume averaging the blood of interconnect capillaries is separated from the arterial and venous blood phases. It is found that in addition to blood perfusion rate, the arrangement of vascular network has considerable effects on the pattern and amount of the achieved temperature. In contrast to counter-current network, the co-current network of vessels leads to considerable asymmetric pattern of temperature contours and relocation of heat affected zone along the blood flow direction. However this relocation can be prevented by changing the site of hyperthermia heat source. The results show that the cooling effect of co-current blood vessels during of interstitial heating is more efficient. Despite much anatomical dissimilarities, these findings can be useful in designing of protocols for hyperthermia cancer treatment of living tissue. Copyright © 2016 Elsevier Ltd. All rights reserved.

In-vitro analysis of early calcification in aortic valvular interstitial cells using Laser-Induced Breakdown Spectroscopy (LIBS).

PubMed

Davari, Seyyed Ali; Masjedi, Shirin; Ferdous, Zannatul; Mukherjee, Dibyendu

2018-01-01

Calcific aortic valve disease (CAVD) is a major cardiovascular disorder caused by osteogenic differentiation of valvular interstitial cells (VICs) within aortic valves. Conventional methods like colorimetric assays and histology fail to detect small calcium depositions during in-vitro VIC cultures. Laser-induced breakdown spectroscopy (LIBS) is a robust analytical tool used for inorganic materials characterizations, but relatively new to biomedical applications. We employ LIBS, for the first time, for quantitative in-vitro detection of calcium depositions in VICs at various osteogenic differentiation stages. VICs isolated from porcine aortic valves were cultured in osteogenic media over various days. Colorimetric calcium assays based on arsenazo dye and Von Kossa staining measured the calcium depositions within VICs. Simultaneously, LIBS signatures for Ca I (422.67 nm) atomic emission lines were collected for estimating calcium depositions in lyophilized VIC samples. Our results indicate excellent linear correlation between the calcium assay and our LIBS measurements. Furthermore, unlike the assay results, the LIBS results could resolve calcium signals from cell samples with as early as 2 days of osteogenic culture. Quantitatively, the LIBS measurements establish the limit of detection for calcium content in VICs to be ∼0.17±0.04 μg which indicates a 5-fold improvement over calcium assay. Picture: Quantitative LIBS enables in-vitro analysis for early stage detection of calcium deposition within aortic valvular interstitial cells (VICs). © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Interstitial water studies on small core samples, Leg 15

USGS Publications Warehouse

Sayles, Fred L.; Manheim, Frank T.; Waterman, Lee S.

1973-01-01

Analyses of pore fluids from reducing environments demonstrate that reduction of SO4 is accompanied by large increases in alkalinity and strong depletion of Ca and Mg. The data are compatible with a model of replacement of Fe3+ in clay lattices by Mg from the interstitial solutions and the precipitation of pyrite. Depletions of Na in the interstitial solutions are related to Mg losses by a ratio of approximately 1:3. Pore fluids from oxidizing pelagic sediments exhibit little SO4 depletion. Losses of Mg are accompanied by the addition of Ca to the pore solutions on a nearly 1:1 basis. Strong Sr enrichment is also found in these solutions. The magnitude of the Sr increase suggests that considerable carbonate recrystallization has occurred. As part of an extensive interlaboratory and analytical calibration, the effect of squeezing sediment at different temperatures has been studied in depth. Samples of a variety of lithologies have been included. Enrichment of K by as much as 24 percent and depletion of Mg and Ca by up to 7 percent occurs during warming. However, no significant effect upon Cl and SO4 could be detected. The strongest effects are seen in the minor constituents studied. On warming, Sr, Si, and B are enriched as much as 19, 40, and 60 percent, respectively. The size of the observed concentration changes varies with the mineralogy of the sediment, but is significant in all types studied, particularly with regards to Mg and K.

Local Higher-Order Graph Clustering

PubMed Central

Yin, Hao; Benson, Austin R.; Leskovec, Jure; Gleich, David F.

2018-01-01

Local graph clustering methods aim to find a cluster of nodes by exploring a small region of the graph. These methods are attractive because they enable targeted clustering around a given seed node and are faster than traditional global graph clustering methods because their runtime does not depend on the size of the input graph. However, current local graph partitioning methods are not designed to account for the higher-order structures crucial to the network, nor can they effectively handle directed networks. Here we introduce a new class of local graph clustering methods that address these issues by incorporating higher-order network information captured by small subgraphs, also called network motifs. We develop the Motif-based Approximate Personalized PageRank (MAPPR) algorithm that finds clusters containing a seed node with minimal motif conductance, a generalization of the conductance metric for network motifs. We generalize existing theory to prove the fast running time (independent of the size of the graph) and obtain theoretical guarantees on the cluster quality (in terms of motif conductance). We also develop a theory of node neighborhoods for finding sets that have small motif conductance, and apply these results to the case of finding good seed nodes to use as input to the MAPPR algorithm. Experimental validation on community detection tasks in both synthetic and real-world networks, shows that our new framework MAPPR outperforms the current edge-based personalized PageRank methodology. PMID:29770258

Low-temperature irradiation-induced defects in germanium: In situ analysis

NASA Astrophysics Data System (ADS)

Mesli, A.; Dobaczewski, L.; Nielsen, K. Bonde; Kolkovsky, Vl.; Petersen, M. Christian; Larsen, A. Nylandsted

2008-10-01

The electronic properties of defects resulting from electron irradiation of germanium at low temperatures have been investigated. The recent success in preparing n+p junctions on germanium has opened a new opportunity to address fundamental questions regarding point defects and their related energy levels by allowing an access to the lower half of the band gap. In this work we apply various space-charge capacitance-transient spectroscopy techniques connected on line with the electron-beam facility. In n -type germanium we identify a level at about 0.14 eV below the conduction band whose properties resemble in many respects those of a defect assigned previously to the close vacancy-interstitial or Frenkel pair. This pair seems to annihilate over a small barrier at about 70 K, and its stability is particularly sensitive to the irradiation temperature and energy. We also observe two coupled levels at 0.08 and 0.24 eV below the conduction band stable up to 160 K. Recent independent theoretical work has predicted the existence of the single and double donor of the germanium interstitial with energy levels matching exactly these two values. Given these identifications hold, they mark a major difference with silicon where both the Frenkel pair and self-interstitial have never been caught. In p -type germanium, two levels were found. The shallower one, located at about 0.14 eV above the valence band, is tentatively assigned to the vacancy. It exhibits a field-driven instability at about 80 K making its analysis quite difficult. The application of a reverse bias, required by the space-charge spectroscopy, leads to a strong drift process sweeping this defect out of the observation area without necessarily provoking its annealing. Unlike silicon, in which the vacancy has four charge states, only one vacancy-related level seems to exist in germanium and this level is very likely a double acceptor. Finally, a very peculiar observation is made on a hole midgap trap, which, in many respects, behaves as the boron interstitial in silicon. This has led us to suggest that it may stem from the gallium interstitial, a natural dopant of our germanium materials, whose presence would be the fingerprint of the Watkins replacement mechanism in germanium.

Implant strategies for endocervical and interstitial ultrasound hyperthermia adjunct to HDR brachytherapy for the treatment of cervical cancer

NASA Astrophysics Data System (ADS)

Wootton, Jeffery H.; Prakash, Punit; Hsu, I.-Chow Joe; Diederich, Chris J.

2011-07-01

Catheter-based ultrasound devices provide a method to deliver 3D conformable heating integrated with HDR brachytherapy delivery. Theoretical characterization of heating patterns was performed to identify implant strategies for these devices which can best be used to apply hyperthermia to cervical cancer. A constrained optimization-based hyperthermia treatment planning platform was used for the analysis. The proportion of tissue >=41 °C in a hyperthermia treatment volume was maximized with constraints Tmax <= 47 °C, Trectum <= 41.5 °C, and Tbladder <= 42.5 °C. Hyperthermia treatment was modeled for generalized implant configurations and complex configurations from a database of patients (n = 14) treated with HDR brachytherapy. Various combinations of endocervical (360° or 2 × 180° output; 6 mm OD) and interstitial (180°, 270°, or 360° output; 2.4 mm OD) applicators within catheter locations from brachytherapy implants were modeled, with perfusion constant (1 or 3 kg m-3 s-1) or varying with location or temperature. Device positioning, sectoring, active length and aiming were empirically optimized to maximize thermal coverage. Conformable heating of appreciable volumes (>200 cm3) is possible using multiple sectored interstitial and endocervical ultrasound devices. The endocervical device can heat >41 °C to 4.6 cm diameter compared to 3.6 cm for the interstitial. Sectored applicators afford tight control of heating that is robust to perfusion changes in most regularly spaced configurations. T90 in example patient cases was 40.5-42.7 °C (1.9-39.6 EM43 °C) at 1 kg m-3 s-1 with 10/14 patients >=41 °C. Guidelines are presented for positioning of implant catheters during the initial surgery, selection of ultrasound applicator configurations, and tailored power schemes for achieving T90 >= 41 °C in clinically practical implant configurations. Catheter-based ultrasound devices, when adhering to the guidelines, show potential to generate conformal therapeutic heating ranging from a single endocervical device targeting small volumes local to the cervix (<2 cm radial) to a combination of a 2 × 180° endocervical and directional interstitial applicators in the lateral periphery to target much larger volumes (6 cm radial), while preferentially limiting heating of the bladder and rectum.

Tuberculosis outbreaks predicted by characteristics of first patients in a DNA fingerprint cluster.

PubMed

Kik, Sandra V; Verver, Suzanne; van Soolingen, Dick; de Haas, Petra E W; Cobelens, Frank G; Kremer, Kristin; van Deutekom, Henk; Borgdorff, Martien W

2008-07-01

Some clusters of patients who have Mycobacterium tuberculosis isolates with identical DNA fingerprint patterns grow faster than others. It is unclear what predictors determine cluster growth. To assess whether the development of a tuberculosis (TB) outbreak can be predicted by the characteristics of its first two patients. Demographic and clinical data of all culture-confirmed patients with TB in the Netherlands from 1993 through 2004 were combined with DNA fingerprint data. Clusters were restricted to cluster episodes of 2 years to only detect newly arising clusters. Characteristics of the first two patients were compared between small (2-4 cases) and large (5 or more cases) cluster episodes. Of 5,454 clustered cases, 1,756 (32%) were part of a cluster episode of 2 years. Of 622 cluster episodes, 54 (9%) were large and 568 (91%) were small episodes. Independent predictors for large cluster episodes were as follows: less than 3 months' time between the diagnosis of the first two patients, one or both patients were young (<35 yr), both patients lived in an urban area, and both patients came from sub-Saharan Africa. In the Netherlands, patients in new cluster episodes should be screened for these risk factors. When the risk pattern applies, targeted interventions (e.g., intensified contact investigation) should be considered to prevent further cluster expansion.

Extracting Aggregation Free Energies of Mixed Clusters from Simulations of Small Systems: Application to Ionic Surfactant Micelles.

PubMed

Zhang, X; Patel, L A; Beckwith, O; Schneider, R; Weeden, C J; Kindt, J T

2017-11-14

Micelle cluster distributions from molecular dynamics simulations of a solvent-free coarse-grained model of sodium octyl sulfate (SOS) were analyzed using an improved method to extract equilibrium association constants from small-system simulations containing one or two micelle clusters at equilibrium with free surfactants and counterions. The statistical-thermodynamic and mathematical foundations of this partition-enabled analysis of cluster histograms (PEACH) approach are presented. A dramatic reduction in computational time for analysis was achieved through a strategy similar to the selector variable method to circumvent the need for exhaustive enumeration of the possible partitions of surfactants and counterions into clusters. Using statistics from a set of small-system (up to 60 SOS molecules) simulations as input, equilibrium association constants for micelle clusters were obtained as a function of both number of surfactants and number of associated counterions through a global fitting procedure. The resulting free energies were able to accurately predict micelle size and charge distributions in a large (560 molecule) system. The evolution of micelle size and charge with SOS concentration as predicted by the PEACH-derived free energies and by a phenomenological four-parameter model fit, along with the sensitivity of these predictions to variations in cluster definitions, are analyzed and discussed.

Analysis of the electron density features of small boron clusters and the effects of doping with C, P, Al, Si, and Zn: Magic B7P and B8Si clusters

NASA Astrophysics Data System (ADS)

Saha, P.; Rahane, A. B.; Kumar, V.; Sukumar, N.

2016-05-01

Boron atomic clusters show several interesting and unusual size-dependent features due to the small covalent radius, electron deficiency, and higher coordination number of boron as compared to carbon. These include aromaticity and a diverse array of structures such as quasi-planar, ring or tubular shaped, and fullerene-like. In the present work, we have analyzed features of the computed electron density distributions of small boron clusters having up to 11 boron atoms, and investigated the effect of doping with C, P, Al, Si, and Zn atoms on their structural and physical properties, in order to understand the bonding characteristics and discern trends in bonding and stability. We find that in general there are covalent bonds as well as delocalized charge distribution in these clusters. We associate the strong stability of some of these planar/quasiplanar disc-type clusters with the electronic shell closing with effectively twelve delocalized valence electrons using a disc-shaped jellium model. {{{{B}}}9}-, B10, B7P, and B8Si, in particular, are found to be exceptional with very large gaps between the highest occupied molecular orbital and the lowest unoccupied molecular orbital, and these are suggested to be magic clusters.

Synthesis, characterization and optical properties of an amino-functionalized gold thiolate cluster: Au10(SPh-pNH2)10.

PubMed

Lavenn, Christophe; Albrieux, Florian; Tuel, Alain; Demessence, Aude

2014-03-15

Research interest in ultra small gold thiolate clusters has been rising in recent years for the challenges they offer to bring together properties of nanoscience and well-defined materials from molecular chemistry. Here, a new atomically well-defined Au10 gold nanocluster surrounded by ten 4-aminothiophenolate ligands is reported. Its synthesis followed the similar conditions reported for the elaboration of Au144(SR)60, but because the reactivity of thiophenol ligands is different from alkanethiol derivates, smaller Au10 clusters were formed. Different techniques, such as ESI-MS, elemental analysis, XRD, TGA, XPS and UV-vis-NIR experiments, have been carried out to determine the Au10(SPh-pNH2)10 formula. Photoemission experiment has been done and reveals that the Au10 clusters are weakly luminescent as opposed to the amino-based ultra-small gold clusters. This observation points out that the emission of gold thiolate clusters is highly dependent on both the structure of the gold core and the type of the ligands at the surface. In addition, ultra-small amino-functionalized clusters offer the opportunity for extended work on self-assembling networks or deposition on substrates for nanotechnologies or catalytic applications. Copyright © 2013 Elsevier Inc. All rights reserved.

Finite-sample corrected generalized estimating equation of population average treatment effects in stepped wedge cluster randomized trials.

PubMed

Scott, JoAnna M; deCamp, Allan; Juraska, Michal; Fay, Michael P; Gilbert, Peter B

2017-04-01

Stepped wedge designs are increasingly commonplace and advantageous for cluster randomized trials when it is both unethical to assign placebo, and it is logistically difficult to allocate an intervention simultaneously to many clusters. We study marginal mean models fit with generalized estimating equations for assessing treatment effectiveness in stepped wedge cluster randomized trials. This approach has advantages over the more commonly used mixed models that (1) the population-average parameters have an important interpretation for public health applications and (2) they avoid untestable assumptions on latent variable distributions and avoid parametric assumptions about error distributions, therefore, providing more robust evidence on treatment effects. However, cluster randomized trials typically have a small number of clusters, rendering the standard generalized estimating equation sandwich variance estimator biased and highly variable and hence yielding incorrect inferences. We study the usual asymptotic generalized estimating equation inferences (i.e., using sandwich variance estimators and asymptotic normality) and four small-sample corrections to generalized estimating equation for stepped wedge cluster randomized trials and for parallel cluster randomized trials as a comparison. We show by simulation that the small-sample corrections provide improvement, with one correction appearing to provide at least nominal coverage even with only 10 clusters per group. These results demonstrate the viability of the marginal mean approach for both stepped wedge and parallel cluster randomized trials. We also study the comparative performance of the corrected methods for stepped wedge and parallel designs, and describe how the methods can accommodate interval censoring of individual failure times and incorporate semiparametric efficient estimators.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lupi, Laura; Kastelowitz, Noah; Molinero, Valeria, E-mail: Valeria.Molinero@utah.edu

Carbonaceous surfaces are a major source of atmospheric particles and could play an important role in the formation of ice. Here we investigate through molecular simulations the stability, metastability, and molecular pathways of deposition of amorphous ice, bilayer ice, and ice I from water vapor on graphitic and atomless Lennard-Jones surfaces as a function of temperature. We find that bilayer ice is the most stable ice polymorph for small cluster sizes, nevertheless it can grow metastable well above its region of thermodynamic stability. In agreement with experiments, the simulations predict that on increasing temperature the outcome of water deposition ismore » amorphous ice, bilayer ice, ice I, and liquid water. The deposition nucleation of bilayer ice and ice I is preceded by the formation of small liquid clusters, which have two wetting states: bilayer pancake-like (wetting) at small cluster size and droplet-like (non-wetting) at larger cluster size. The wetting state of liquid clusters determines which ice polymorph is nucleated: bilayer ice nucleates from wetting bilayer liquid clusters and ice I from non-wetting liquid clusters. The maximum temperature for nucleation of bilayer ice on flat surfaces, T{sub B}{sup max} is given by the maximum temperature for which liquid water clusters reach the equilibrium melting line of bilayer ice as wetting bilayer clusters. Increasing water-surface attraction stabilizes the pancake-like wetting state of liquid clusters leading to larger T{sub B}{sup max} for the flat non-hydrogen bonding surfaces of this study. The findings of this study should be of relevance for the understanding of ice formation by deposition mode on carbonaceous atmospheric particles, including soot.« less

Fragile sites, dysfunctional telomere and chromosome fusions: What is 5S rDNA role?

PubMed

Barros, Alain Victor; Wolski, Michele Andressa Vier; Nogaroto, Viviane; Almeida, Mara Cristina; Moreira-Filho, Orlando; Vicari, Marcelo Ricardo

2017-04-15

Repetitive DNA regions are known as fragile chromosomal sites which present a high flexibility and low stability. Our focus was characterize fragile sites in 5S rDNA regions. The Ancistrus sp. species shows a diploid number of 50 and an indicative Robertsonian fusion at chromosomal pair 1. Two sequences of 5S rDNA were identified: 5S.1 rDNA and 5S.2 rDNA. The first sequence gathers the necessary structures to gene expression and shows a functional secondary structure prediction. Otherwise, the 5S.2 rDNA sequence does not contain the upstream sequences that are required to expression, furthermore its structure prediction reveals a nonfunctional ribosomal RNA. The chromosomal mapping revealed several 5S.1 and 5S.2 rDNA clusters. In addition, the 5S.2 rDNA clusters were found in acrocentric and metacentric chromosomes proximal regions. The pair 1 5S.2 rDNA cluster is co-located with interstitial telomeric sites (ITS). Our results indicate that its clusters are hotspots to chromosomal breaks. During the meiotic prophase bouquet arrangement, double strand breaks (DSBs) at proximal 5S.2 rDNA of acrocentric chromosomes could lead to homologous and non-homologous repair mechanisms as Robertsonian fusions. Still, ITS sites provides chromosomal instability, resulting in telomeric recombination via TRF2 shelterin protein and a series of breakage-fusion-bridge cycles. Our proposal is that 5S rDNA derived sequences, act as chromosomal fragile sites in association with some chromosomal rearrangements of Loricariidae. Copyright © 2017 Elsevier B.V. All rights reserved.

Interactions of small platinum clusters with the TiC(001) surface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mao, Jianjun; Li, Shasha; Chu, Xingli

2015-11-14

Density functional theory calculations are used to elucidate the interactions of small platinum clusters (Pt{sub n}, n = 1–5) with the TiC(001) surface. The results are analyzed in terms of geometric, energetic, and electronic properties. It is found that a single Pt atom prefers to be adsorbed at the C-top site, while a Pt{sub 2} cluster prefers dimerization and a Pt{sub 3} cluster forms a linear structure on the TiC(001). As for the Pt{sub 4} cluster, the three-dimensional distorted tetrahedral structure and the two-dimensional square structure almost have equal stability. In contrast with the two-dimensional isolated Pt{sub 5} cluster, the adsorbed Pt{submore » 5} cluster prefers a three-dimensional structure on TiC(001). Substantial charge transfer takes place from TiC(001) surface to the adsorbed Pt{sub n} clusters, resulting in the negatively charged Pt{sub n} clusters. At last, the d-band centers of the absorbed Pt atoms and their implications in the catalytic activity are discussed.« less

Spectroscopic determination of fundamental parameters of small angular diameter galactic open clusters

NASA Astrophysics Data System (ADS)

Ahumada, A. V.; Claria, J. J.; Bica, E.; Parisi, M. C.; Torres, M. C.; Pavani, D. B.

We present integrated spectra obtained at CASLEO (Argentina) for 9 galactic open clusters of small angular diameter. Two of them (BH 55 and Rup 159) have not been the target of previous research. The flux-calibrated spectra cover the spectral range approx. 3600-6900 A. Using the equivalent widths (EWs) of the Balmer lines and comparing the cluster spectra with template spectra, we determined E(B-V) colour excesses and ages for the present cluster sample. The parameters obtained for 6 of the clusters show good agreement with previous determinations based mainly on photometric methods. This is not the case, however, for BH 90, a scarcely reddened cluster, for which Moffat and Vogt (1975, Astron. and Astroph. SS, 20, 125) derived E(B-V) = 0.51. We explain and justify the strong discrepancy found for this object. According to the present analysis, 3 clusters are very young (Bo 14, Tr 15 and Tr 27), 2 are moderately young (NGC 6268 and BH 205), 3 are Hyades-like clusters (Rup 164, BH 90 and BH 55) and only one is an intermediate-age cluster (Rup 159).

Internal velocity and mass distributions in simulated clusters of galaxies for a variety of cosmogonic models

NASA Technical Reports Server (NTRS)

Cen, Renyue

1994-01-01

The mass and velocity distributions in the outskirts (0.5-3.0/h Mpc) of simulated clusters of galaxies are examined for a suite of cosmogonic models (two Omega(sub 0) = 1 and two Omega(sub 0) = 0.2 models) utilizing large-scale particle-mesh (PM) simulations. Through a series of model computations, designed to isolate the different effects, we find that both Omega(sub 0) and P(sub k) (lambda less than or = 16/h Mpc) are important to the mass distributions in clusters of galaxies. There is a correlation between power, P(sub k), and density profiles of massive clusters; more power tends to point to the direction of a stronger correlation between alpha and M(r less than 1.5/h Mpc); i.e., massive clusters being relatively extended and small mass clusters being relatively concentrated. A lower Omega(sub 0) universe tends to produce relatively concentrated massive clusters and relatively extended small mass clusters compared to their counterparts in a higher Omega(sub 0) model with the same power. Models with little (initial) small-scale power, such as the hot dark matter (HDM) model, produce more extended mass distributions than the isothermal distribution for most of the mass clusters. But the cold dark matter (CDM) models show mass distributions of most of the clusters more concentrated than the isothermal distribution. X-ray and gravitational lensing observations are beginning providing useful information on the mass distribution in and around clusters; some interesting constraints on Omega(sub 0) and/or the (initial) power of the density fluctuations on scales lambda less than or = 16/h Mpc (where linear extrapolation is invalid) can be obtained when larger observational data sets, such as the Sloan Digital Sky Survey, become available.

The Distribution of Ammonia-Oxidizing Betaproteobacteria in Stands of Black Mangroves (Avicennia germinans)

PubMed Central

Laanbroek, Hendrikus J.; Keijzer, Rosalinde M.; Verhoeven, Jos T. A.; Whigham, Dennis F.

2012-01-01

The distribution of species of aerobic chemolitho-autotrophic microorganisms such as ammonia-oxidizing bacteria are governed by pH, salinity, and temperature as well as the availability of oxygen, ammonium, carbon dioxide, and other inorganic elements required for growth. Impounded mangrove forests in the Indian River Lagoon, a coastal estuary on the east coast of Florida, are dominated by mangroves, especially stands of Black mangrove (Avicennia germinans) that differ in the size and density of individual plants. In March 2009, the management of one impoundment was changed to a regime of pumping estuarine water into the impoundment at critical times of the year to eliminate breeding sites for noxious insects. We collected soil samples in three different Black mangrove habitats before and after the change in management to determine the impacts of the altered hydrologic regimes on the distribution of 16s rRNA genes belonging to ammonia-oxidizing betaproteobacteria (β-AOB). We also sampled soils in an adjacent impoundment in which there had not been any hydrologic alteration. At the level of 97% mutual similarity in the 16s rRNA gene, 13 different operational taxonomic units were identified; the majority related to the lineages of Nitrosomonas marina (45% of the total clones), Nitrosomonas sp. Nm143 (23%), and Nitrosospira cluster 1 (19%). Long-term summer flooding of the impoundment in 2009, after initiation of the pumping regime, reduced the percentage of N. marina by half between 2008 and 2010 in favor of the two other major lineages and the potential ammonia-oxidizing activity decreased by an average of 73%. Higher interstitial salinities, probably due to a prolonged winter drought, had a significant effect on the composition of the β-AOB in March 2009 compared to March 2008: Nitrosomonas sp. Nm143 was replaced by Nitrosospira cluster 1 as the second most important lineage. There were small, but significant differences in the bacterial communities between the flooded and non-flooded impoundments. There were also differences in the community composition of the bacteria in the three Black mangrove habitats. N. marina was most dominant in all three habitats, but was partly replaced by Nitrosospira cluster 1 in sites dominated by sparsely distributed trees and by Nitrosomonas sp. Nm143 in sites characterized by taller, more densely distributed Black mangrove trees. PMID:22536201

Coupled multipolar interactions in small-particle metallic clusters.

PubMed

Pustovit, Vitaly N; Sotelo, Juan A; Niklasson, Gunnar A

2002-03-01

We propose a new formalism for computing the optical properties of small clusters of particles. It is a generalization of the coupled dipole-dipole particle-interaction model and allows one in principle to take into account all multipolar interactions in the long-wavelength limit. The method is illustrated by computations of the optical properties of N = 6 particle clusters for different multipolar approximations. We examine the effect of separation between particles and compare the optical spectra with the discrete-dipole approximation and the generalized Mie theory.

A Theoretical Study of Structural, Electronic and Vibrational Properties of Small Fluoride Clusters

NASA Astrophysics Data System (ADS)

Waters, Kevin; Pandey, Ratnesh; Nigam, Sandeep; He, Haiying; Pingle, Subhash; Pandey, Avinash; Pandey, Ravindra

2014-03-01

Alkaline earth metal fluorides are an interesting family of ionic crystals having a wide range of applications in solid state lasers, luminescence, scintillators, to name just a few. In this work, small stoichiometric clusters of (MF2)n (M = Mg, Ca Sr, Ba, n =1-6) were studied for structural, vibrational and electronic properties using first-principles methods based on density functional theory. A clear trend of structural and electronic structure evolution was found for all the alkaline earth metal fluorides when the cluster size n increases from 1 to 6. Our study reveals that these fluoride clusters mimic the bulk-like behavior at the very small size. Among the four series of metal fluorides, however, (MgF2)n clusters stands out to be different in its preference of equilibrium structures owing to the much smaller ionic radius of Mg and the higher degree of covalency in the Mg-F bonding. The calculated binding energy, highest stretching frequency, ionization potential, and HOMO-LUMO gap decrease from MgF2 to BaF2 for the same cluster size. These variations are explained in terms of the change in the ionic radius and the basicity of the metal ions.

Relative dispersion of clustered drifters in a small micro-tidal estuary

NASA Astrophysics Data System (ADS)

Suara, Kabir; Chanson, Hubert; Borgas, Michael; Brown, Richard J.

2017-07-01

Small tide-dominated estuaries are affected by large scale flow structures which combine with the underlying bed generated smaller scale turbulence to significantly increase the magnitude of horizontal diffusivity. Field estimates of horizontal diffusivity and its associated scales are however rare due to limitations in instrumentation. Data from multiple deployments of low and high resolution clusters of GPS-drifters are used to examine the dynamics of a surface flow in a small micro-tidal estuary through relative dispersion analyses. During the field study, cluster diffusivity, which combines both large- and small-scale processes ranged between, 0.01 and 3.01 m2/s for spreading clusters and, -0.06 and -4.2 m2/s for contracting clusters. Pair-particle dispersion, Dp2, was scale dependent and grew as Dp2 ∼ t1.83 in streamwise and Dp2 ∼ t0.8 in cross-stream directions. At small separation scale, pair-particle (d < 0.5 m) relative diffusivity followed the Richardson's 4/3 power law and became weaker as separation scale increases. Pair-particle diffusivity was described as Kp ∼ d1.01 and Kp ∼ d0.85 in the streamwise and cross-stream directions, respectively for separation scales ranging from 0.1 to 10 m. Two methods were used to identify the mechanism responsible for dispersion within the channel. The results clearly revealed the importance of strain fields (stretching and shearing) in the spreading of particles within a small micro-tidal channel. The work provided input for modelling dispersion of passive particle in shallow micro-tidal estuaries where these were not previously experimentally studied.

Casting core for a cooling arrangement for a gas turbine component

DOEpatents

Lee, Ching-Pang; Heneveld, Benjamin E

2015-01-20

A ceramic casting core, including: a plurality of rows (162, 166, 168) of gaps (164), each gap (164) defining an airfoil shape; interstitial core material (172) that defines and separates adjacent gaps (164) in each row (162, 166, 168); and connecting core material (178) that connects adjacent rows (170, 174, 176) of interstitial core material (172). Ends of interstitial core material (172) in one row (170, 174, 176) align with ends of interstitial core material (172) in an adjacent row (170, 174, 176) to form a plurality of continuous and serpentine shaped structures each including interstitial core material (172) from at least two adjacent rows (170, 174, 176) and connecting core material (178).

Critical behavior of the contact process on small-world networks

NASA Astrophysics Data System (ADS)

Ferreira, Ronan S.; Ferreira, Silvio C.

2013-11-01

We investigate the role of clustering on the critical behavior of the contact process (CP) on small-world networks using the Watts-Strogatz (WS) network model with an edge rewiring probability p. The critical point is well predicted by a homogeneous cluster-approximation for the limit of vanishing clustering ( p → 1). The critical exponents and dimensionless moment ratios of the CP are in agreement with those predicted by the mean-field theory for any p > 0. This independence on the network clustering shows that the small-world property is a sufficient condition for the mean-field theory to correctly predict the universality of the model. Moreover, we compare the CP dynamics on WS networks with rewiring probability p = 1 and random regular networks and show that the weak heterogeneity of the WS network slightly changes the critical point but does not alter other critical quantities of the model.

The prevalence and overlap of interstitial cystitis/bladder pain syndrome and chronic prostatitis/chronic pelvic pain syndrome in men: results of the RAND Interstitial Cystitis Epidemiology male study.

PubMed

Suskind, Anne M; Berry, Sandra H; Ewing, Brett A; Elliott, Marc N; Suttorp, Marika J; Clemens, J Quentin

2013-01-01

As part of the RICE (RAND Interstitial Cystitis Epidemiology) study, we developed validated case definitions to identify interstitial cystitis/bladder pain syndrome in women and chronic prostatitis/chronic pelvic pain syndrome in men. Using population based screening methods, we applied these case definitions to determine the prevalence of these conditions in men. A total of 6,072 households were contacted by telephone to screen for men who had symptoms of interstitial cystitis/bladder pain syndrome or chronic prostatitis/chronic pelvic pain syndrome. An initial 296 men screened positive, of whom 149 met the inclusionary criteria and completed the telephone interview. For interstitial cystitis/bladder pain syndrome 2 case definitions were applied (1 with high sensitivity and 1 with high specificity), while for chronic prostatitis/chronic pelvic pain syndrome a single case definition (with high sensitivity and specificity) was used. These case definitions were used to classify subjects into groups based on diagnosis. The interstitial cystitis/bladder pain syndrome weighted prevalence estimates for the high sensitivity and high specificity definitions were 4.2% (3.1-5.3) and 1.9% (1.1-2.7), respectively. The chronic prostatitis/chronic pelvic pain syndrome weighted prevalence estimate was 1.8% (0.9-2.7). These values equate to 1,986,972 (95% CI 966,042-2,996,924) men with chronic prostatitis/chronic pelvic pain syndrome and 2,107,727 (95% CI 1,240,485-2,974,969) men with the high specificity definition of interstitial cystitis/bladder pain syndrome in the United States. The overlap between men who met the high specificity interstitial cystitis/bladder pain syndrome case definition or the chronic prostatitis/chronic pelvic pain syndrome case definition was 17%. Symptoms of interstitial cystitis/bladder pain syndrome and chronic prostatitis/chronic pelvic pain syndrome are widespread among men in the United States. The prevalence of interstitial cystitis/bladder pain syndrome symptoms in men approaches that in women, suggesting that this condition may be underdiagnosed in the male population. Copyright © 2013 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

A comparison of confidence interval methods for the intraclass correlation coefficient in community-based cluster randomization trials with a binary outcome.

PubMed

Braschel, Melissa C; Svec, Ivana; Darlington, Gerarda A; Donner, Allan

2016-04-01

Many investigators rely on previously published point estimates of the intraclass correlation coefficient rather than on their associated confidence intervals to determine the required size of a newly planned cluster randomized trial. Although confidence interval methods for the intraclass correlation coefficient that can be applied to community-based trials have been developed for a continuous outcome variable, fewer methods exist for a binary outcome variable. The aim of this study is to evaluate confidence interval methods for the intraclass correlation coefficient applied to binary outcomes in community intervention trials enrolling a small number of large clusters. Existing methods for confidence interval construction are examined and compared to a new ad hoc approach based on dividing clusters into a large number of smaller sub-clusters and subsequently applying existing methods to the resulting data. Monte Carlo simulation is used to assess the width and coverage of confidence intervals for the intraclass correlation coefficient based on Smith's large sample approximation of the standard error of the one-way analysis of variance estimator, an inverted modified Wald test for the Fleiss-Cuzick estimator, and intervals constructed using a bootstrap-t applied to a variance-stabilizing transformation of the intraclass correlation coefficient estimate. In addition, a new approach is applied in which clusters are randomly divided into a large number of smaller sub-clusters with the same methods applied to these data (with the exception of the bootstrap-t interval, which assumes large cluster sizes). These methods are also applied to a cluster randomized trial on adolescent tobacco use for illustration. When applied to a binary outcome variable in a small number of large clusters, existing confidence interval methods for the intraclass correlation coefficient provide poor coverage. However, confidence intervals constructed using the new approach combined with Smith's method provide nominal or close to nominal coverage when the intraclass correlation coefficient is small (<0.05), as is the case in most community intervention trials. This study concludes that when a binary outcome variable is measured in a small number of large clusters, confidence intervals for the intraclass correlation coefficient may be constructed by dividing existing clusters into sub-clusters (e.g. groups of 5) and using Smith's method. The resulting confidence intervals provide nominal or close to nominal coverage across a wide range of parameters when the intraclass correlation coefficient is small (<0.05). Application of this method should provide investigators with a better understanding of the uncertainty associated with a point estimator of the intraclass correlation coefficient used for determining the sample size needed for a newly designed community-based trial. © The Author(s) 2015.

Dating star clusters in the Small Magellanic Cloud by means of integrated spectra

NASA Astrophysics Data System (ADS)

Ahumada, A. V.; Clariá, J. J.; Bica, E.; Dutra, C. M.

2002-10-01

In this study flux-calibrated integrated spectra in the range (3600-6800) Å are presented for 16 concentrated star clusters in the Small Magellanic Cloud (SMC), approximately half of which constitute unstudied objects. We have estimated ages and foreground interstellar reddening values from the comparison of the line strengths and continuum distribution of the cluster spectra with those of template cluster spectra with known parameters. Most of the sample clusters are young blue clusters (6-50 Myr), while L 28, NGC 643 and L 114 are found to be intermediate-age clusters (1-6 Gyr). One well known SMC cluster (NGC 416) was observed for comparison purposes. The sample includes clusters in the surroundings and main body of the SMC, and the derived foreground reddening values are in the range 0.00 <= E(B-V) <= 0.15. The present data also make up a cluster spectral library at SMC metallicity. Based on observations made at Complejo Astronómico El Leoncito, which is operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina and the National Universities of La Plata, Córdoba and San Juan, Argentina.

Chromosomal organization of four classes of repetitive DNA sequences in killifish Orestias ascotanensis Parenti, 1984 (Cyprinodontiformes, Cyprinodontidae)

PubMed Central

Araya-Jaime, Cristian; Lam, Natalia; Pinto, Irma Vila; Méndez, Marco A.; Iturra, Patricia

2017-01-01

Abstract Orestias Valenciennes, 1839 is a genus of freshwater fish endemic to the South American Altiplano. Cytogenetic studies of these species have focused on conventional karyotyping. The aim of this study was to use classical and molecular cytogenetic methods to identify the constitutive heterochromatin distribution and chromosome organization of four classes of repetitive DNA sequences (histone H3 DNA, U2 snRNA, 18S rDNA and 5S rDNA) in the chromosomes of O. ascotanensis Parenti, 1984, an endemic species restricted to the Salar de Ascotán in the Chilean Altiplano. All individuals analyzed had a diploid number of 48 chromosomes. C-banding identified constitutive heterochromatin mainly in the pericentromeric region of most chromosomes, especially a GC-rich heterochromatic block of the short arm of pair 3. FISH assay with an 18S probe confirmed the location of the NOR in pair 3 and revealed that the minor rDNA cluster occurs interstitially on the long arm of pair 2. Dual FISH identified a single block of U2 snDNA sequences in the pericentromeric regions of a subtelocentric chromosome pair, while histone H3 sites were observed as small signals scattered in throughout the all chromosomes. This work represents the first effort to document the physical organization of the repetitive fraction of the Orestias genome. These data will improve our understanding of the chromosomal evolution of a genus facing serious conservation problems. PMID:29093798

Effect of Self-Assembly of Fullerene Nano-Particles on Lipid Membrane

PubMed Central

Zhang, Saiqun; Mu, Yuguang; Zhang, John Z. H.; Xu, Weixin

2013-01-01

Carbon nanoparticles can penetrate the cell membrane and cause cytotoxicity. The diffusion feature and translocation free energy of fullerene through lipid membranes is well reported. However, the knowledge on self-assembly of fullerenes and resulting effects on lipid membrane is poorly addressed. In this work, the self-assembly of fullerene nanoparticles and the resulting influence on the dioleoylphosphtidylcholine (DOPC) model membrane were studied by using all-atom molecular dynamics simulations with explicit solvents. Our simulation results confirm that gathered small fullerene cluster can invade lipid membrane. Simulations show two pathways: 1) assembly process is completely finished before penetration; 2) assembly process coincides with penetration. Simulation results also demonstrate that in the membrane interior, fullerene clusters tend to stay at the position which is 1.0 nm away from the membrane center. In addition, the diverse microscopic stacking mode (i.e., equilateral triangle, tetrahedral pentahedral, trigonal bipyramid and octahedron) of these small fullerene clusters are well characterized. Thus our simulations provide a detailed high-resolution characterization of the microscopic structures of the small fullerene clusters. Further, we found the gathered small fullerene clusters have significant adverse disturbances to the local structure of the membrane, but no great influence on the global integrity of the lipid membrane, which suggests the prerequisite of high-content fullerene for cytotoxicity. PMID:24204827

The origin of low mass particles within and beyond the dust coma envelopes of Comet Halley

NASA Technical Reports Server (NTRS)

Simpson, J. A.; Rabinowitz, D.; Tuzzolino, A. J.; Ksanfomality, L. V.; Sagdeev, R. Z.

1987-01-01

Measurements from the Dust Counter and Mass Analyzer (DUCMA) instruments on VEGA-1 and -2 revealed unexpected fluxes of low mass (up to 10 to the minus 13th power g) dust particles at very great distances from the nucleus (300,000 to 600,000 km). These particles are detected in clusters (10 sec duration), preceded and followed by relatively long time intervals during which no dust is detected. This cluster phenomenon also occurs inside the envelope boundaries. Clusters of low mass particles are intermixed with the overall dust distribution throughout the coma. The clusters account for many of the short-term small-scale intensity enhancements previously ascribed to microjets in the coma. The origin of these clusters appears to be emission from the nucleus of large conglomerates which disintegrate in the coma to yield clusters of discrete, small particles continuing outward to the distant coma.

Equilibrium geometries, electronic and magnetic properties of small AunNi- (n = 1-9) clusters

NASA Astrophysics Data System (ADS)

Tang, Cui-Ming; Chen, Xiao-Xu; Yang, Xiang-Dong

2014-05-01

Geometrical, electronic and magnetic properties of small AunNi- (n = 1-9) clusters have been investigated based on density functional theory (DFT) at PW91P86 level. An extensive structural search shows that the relative stable structures of AunNi- (n = 1-9) clusters adopt 2D structure for n = 1-5, 7 and 3D structure for n = 6, 8-9. And the substitution of a Ni atom for an Au atom in the Au-n+1 cluster obviously changes the structure of the host cluster. Moreover, an odd-even alternation phenomenon has been found for HOMO-LUMO energy gaps, indicating that the relative stable structures of the AunNi- clusters with odd-numbered gold atoms have a higher relative stability. Finally, the natural population analysis (NPA) and the vertical detachment energies (VDE) are studied, respectively. The theoretical values of VDE are reported for the first time to our best knowledge.

Thermodynamic properties of small aggregates of rare-gas atoms

NASA Technical Reports Server (NTRS)

Etters, R. D.; Kaelberer, J.

1975-01-01

The present work reports on the equilibrium thermodynamic properties of small clusters of xenon, krypton, and argon atoms, determined from a biased random-walk Monte Carlo procedure. Cluster sizes ranged from 3 to 13 atoms. Each cluster was found to have an abrupt liquid-gas phase transition at a temperature much less than for the bulk material. An abrupt solid-liquid transition is observed for thirteen- and eleven-particle clusters. For cluster sizes smaller than 11, a gradual transition from solid to liquid occurred over a fairly broad range of temperatures. Distribution of number of bond lengths as a function of bond length was calculated for several systems at various temperatures. The effects of box boundary conditions are discussed. Results show the importance of a correct description of boundary conditions. A surprising result is the slow rate at which system properties approach bulk behavior as cluster size is increased.

De novo interstitial tandem duplication of chromosome 4(q21-q28)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Navarro, E.G.; Ramon, F.J.H.; Jimenez, R.D.

1996-03-29

We describe a girl with a previously unreported de novo duplication of chromosome 4q involving segment q21-q28. Clinical manifestations included growth and psychomotor retardation, facial asymmetry, hypotelorism, epicanthic folds, mongoloid slant of palpebral fissures, apparently low-set auricles, high nasal bridge, long philtrum, small mouth, short neck, low-set thumbs, and bilateral club foot. This phenotype is compared with that of previously reported cases of duplication 4q. 12 refs., 3 figs., 1 tab.

Sm-Nd Isotopic Studies of Two Nakhlites, NWA 5790 and Nakhla

NASA Technical Reports Server (NTRS)

C.-Y. Shih; Nyquist, L. E.; Reese, Y.; Jambon, A.

2010-01-01

NWA 5790 is a Martian meteorite recently found in the Mauritania part of the Saharan desert and is classified as a nakhlite, containing a small amount of interstitial plagioclase. Unlike other Martian meteorites ( e.g., shergottites), nakhlites have been only moderately shocked and their original igneous textures are still well-preserved. In this report, we present Sm-Nd isotopic data for NWA 5790 and Nakhla, a rare "fall" nakhlite, correlate their ages with those of other nakhlites and discuss their petrogenesis.

Rotation of molecular hydrogen in Si: unambiguous identification of ortho-H(2) and para-D(2).

PubMed

Chen, E Elinor; Stavola, Michael; Beall Fowler, W; Zhou, J Anna

2002-06-17

The 3618.4 and 2642.6 cm(-1) infrared absorption lines of interstitial H(2) and D(2) in silicon have been studied under applied uniaxial stresses. The resulting splittings and their small dependence on isotope establish that H(2) in Si is a nearly free rotor and that these lines arise from vibrational transitions between rovibrational states with rotational quantum number J = 1 (T(2) in T(d) symmetry) for ortho-H(2) and para-D(2).

Interstitial Features at Chest CT Enhance the Deleterious Effects of Emphysema in the COPDGene Cohort.

PubMed

Ash, Samuel Y; Harmouche, Rola; Ross, James C; Diaz, Alejandro A; Rahaghi, Farbod N; Sanchez-Ferrero, Gonzalo Vegas; Putman, Rachel K; Hunninghake, Gary M; Onieva, Jorge Onieva; Martinez, Fernando J; Choi, Augustine M; Bowler, Russell P; Lynch, David A; Hatabu, Hiroto; Bhatt, Surya P; Dransfield, Mark T; Wells, J Michael; Rosas, Ivan O; San Jose Estepar, Raul; Washko, George R

2018-06-05

Purpose To determine if interstitial features at chest CT enhance the effect of emphysema on clinical disease severity in smokers without clinical pulmonary fibrosis. Materials and Methods In this retrospective cohort study, an objective CT analysis tool was used to measure interstitial features (reticular changes, honeycombing, centrilobular nodules, linear scar, nodular changes, subpleural lines, and ground-glass opacities) and emphysema in 8266 participants in a study of chronic obstructive pulmonary disease (COPD) called COPDGene (recruited between October 2006 and January 2011). Additive differences in patients with emphysema with interstitial features and in those without interstitial features were analyzed by using t tests, multivariable linear regression, and Kaplan-Meier analysis. Multivariable linear and Cox regression were used to determine if interstitial features modified the effect of continuously measured emphysema on clinical measures of disease severity and mortality. Results Compared with individuals with emphysema alone, those with emphysema and interstitial features had a higher percentage predicted forced expiratory volume in 1 second (absolute difference, 6.4%; P < .001), a lower percentage predicted diffusing capacity of lung for carbon monoxide (DLCO) (absolute difference, 7.4%; P = .034), a 0.019 higher right ventricular-to-left ventricular (RVLV) volume ratio (P = .029), a 43.2-m shorter 6-minute walk distance (6MWD) (P < .001), a 5.9-point higher St George's Respiratory Questionnaire (SGRQ) score (P < .001), and 82% higher mortality (P < .001). In addition, interstitial features modified the effect of emphysema on percentage predicted DLCO, RVLV volume ratio, 6WMD, SGRQ score, and mortality (P for interaction < .05 for all). Conclusion In smokers, the combined presence of interstitial features and emphysema was associated with worse clinical disease severity and higher mortality than was emphysema alone. In addition, interstitial features enhanced the deleterious effects of emphysema on clinical disease severity and mortality. © RSNA, 2018 Online supplemental material is available for this article.

Numerical Modeling of Fluid Flow in Solid Tumors

PubMed Central

Soltani, M.; Chen, P.

2011-01-01

A mathematical model of interstitial fluid flow is developed, based on the application of the governing equations for fluid flow, i.e., the conservation laws for mass and momentum, to physiological systems containing solid tumors. The discretized form of the governing equations, with appropriate boundary conditions, is developed for a predefined tumor geometry. The interstitial fluid pressure and velocity are calculated using a numerical method, element based finite volume. Simulations of interstitial fluid transport in a homogeneous solid tumor demonstrate that, in a uniformly perfused tumor, i.e., one with no necrotic region, because of the interstitial pressure distribution, the distribution of drug particles is non-uniform. Pressure distribution for different values of necrotic radii is examined and two new parameters, the critical tumor radius and critical necrotic radius, are defined. Simulation results show that: 1) tumor radii have a critical size. Below this size, the maximum interstitial fluid pressure is less than what is generally considered to be effective pressure (a parameter determined by vascular pressure, plasma osmotic pressure, and interstitial osmotic pressure). Above this size, the maximum interstitial fluid pressure is equal to effective pressure. As a consequence, drugs transport to the center of smaller tumors is much easier than transport to the center of a tumor whose radius is greater than the critical tumor radius; 2) there is a critical necrotic radius, below which the interstitial fluid pressure at the tumor center is at its maximum value. If the tumor radius is greater than the critical tumor radius, this maximum pressure is equal to effective pressure. Above this critical necrotic radius, the interstitial fluid pressure at the tumor center is below effective pressure. In specific ranges of these critical sizes, drug amount and therefore therapeutic effects are higher because the opposing force, interstitial fluid pressure, is low in these ranges. PMID:21673952

Influence of interstitial Mn on magnetism in the room-temperature ferromagnet Mn 1 + δ Sb

DOE PAGES

Taylor, Alice E.; Berlijn, Tom; Hahn, Steven E.; ...

2015-06-15

We repormore » t elastic and inelastic neutron scattering measurements of the high-TC ferromagnet Mn 1 + δ Sb . Measurements were performed on a large, T C = 434 K, single crystal with interstitial Mn content of δ ≈ 0.13. The neutron diffraction results reveal that the interstitial Mn has a magnetic moment, and that it is aligned antiparallel to the main Mn moment. We perform density functional theory calculations including the interstitial Mn, and find the interstitial to be magnetic in agreement with the diffraction data. The inelastic neutron scattering measurements reveal two features in the magnetic dynamics: i) a spin-wave-like dispersion emanating from ferromagnetic Bragg positions (H K 2n), and ii) a broad, non-dispersive signal centered at forbidden Bragg positions (H K 2n+1). The inelastic spectrum cannot be modeled by simple linear spin-wave theory calculations, and appears to be significantly altered by the presence of the interstitial Mn ions. Finally, the results show that the influence of the interstitial Mn on the magnetic state in this system is more important than previously understood.« less

The pulmonary histopathology of anti-KS transfer RNA synthetase syndrome.

PubMed

Schneider, Frank; Aggarwal, Rohit; Bi, David; Gibson, Kevin; Oddis, Chester; Yousem, Samuel A

2015-01-01

The clinical spectrum of the antisynthetase syndromes (AS) has been poorly defined, although some frequently present with pulmonary manifestations. The anti-KS anti-asparaginyl-transfer RNA synthetase syndrome is one in which pulmonary interstitial lung disease is almost always present and yet the histopathologic spectrum is not well described. To define the morphologic manifestations of pulmonary disease in those patients with anti-KS antiasparaginyl syndrome. We reviewed the connective tissue disorder registry of the University of Pittsburgh and identified those patients with anti-KS autoantibodies who presented with interstitial lung disease and had surgical lung biopsies. The 5 patients with anti-KS antisynthetase syndrome were usually women presenting with dyspnea and without myositis, but with mechanic's hands (60%) and Raynaud phenomenon (40%). They most often presented with a usual interstitial pneumonia pattern of fibrosis (80%), with the final patient displaying organizing pneumonia. Pulmonary interstitial lung disease is a common presentation in patients with the anti-KS-antisynthetase syndrome, who are often women with rather subtle or subclinical connective tissue disease, whereas the literature emphasizes the nonspecific interstitial pneumonia pattern often diagnosed clinically. Usual interstitial pneumonia and organizing pneumonia patterns of interstitial injury need to be added to this clinical differential diagnosis.

Extracting magnetic cluster size and its distributions in advanced perpendicular recording media with shrinking grain size using small angle x-ray scattering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mehta, Virat; Ikeda, Yoshihiro; Takano, Ken

2015-05-18

We analyze the magnetic cluster size (MCS) and magnetic cluster size distribution (MCSD) in a variety of perpendicular magnetic recording (PMR) media designs using resonant small angle x-ray scattering at the Co L{sub 3} absorption edge. The different PMR media flavors considered here vary in grain size between 7.5 and 9.5 nm as well as in lateral inter-granular exchange strength, which is controlled via the segregant amount. While for high inter-granular exchange, the MCS increases rapidly for grain sizes below 8.5 nm, we show that for increased amount of segregant with less exchange the MCS remains relatively small, even for grain sizesmore » of 7.5 and 8 nm. However, the MCSD still increases sharply when shrinking grains from 8 to 7.5 nm. We show evidence that recording performance such as signal-to-noise-ratio on the spin stand correlates well with the product of magnetic cluster size and magnetic cluster size distribution.« less

A DFT study of the stability of SIAs and small SIA clusters in the vicinity of solute atoms in Fe

NASA Astrophysics Data System (ADS)

Becquart, C. S.; Ngayam Happy, R.; Olsson, P.; Domain, C.

2018-03-01

The energetics, defect volume and magnetic properties of single SIAs and small SIA clusters up to size 6 have been calculated by DFT for different configurations like the parallel 〈110〉 dumbbell, the non parallel 〈110〉 dumbbell and the C15 structure. The most stable configurations of each type have been further analyzed to determine the influence on their stability of various solute atoms (Ti, V, Cr, Mn, Co, Ni, Cu, Mo, W, Pd, Al, Si, P), relevant for steels used under irradiation. The results show that the presence of solute atoms does not change the relative stability order among SIA clusters. The small SIA clusters investigated can bind to both undersized and oversized solutes. Several descriptors have been considered to derive interesting trends from results. It appears that the local atomic volume available for the solute is the main physical quantity governing the binding energy evolution, whatever the solute type (undersized or oversized) and the cluster configuration (size and type).

Effects of manganese doping on the structure evolution of small-sized boron clusters

NASA Astrophysics Data System (ADS)

Zhao, Lingquan; Qu, Xin; Wang, Yanchao; Lv, Jian; Zhang, Lijun; Hu, Ziyu; Gu, Guangrui; Ma, Yanming

2017-07-01

Atomic doping of clusters is known as an effective approach to stabilize or modify the structures and properties of resulting doped clusters. We herein report the effect of manganese (Mn) doping on the structure evolution of small-sized boron (B) clusters. The global minimum structures of both neutral and charged Mn doped B cluster \\text{MnB}nQ (n  =  10-20 and Q  =  0, ±1) have been proposed through extensive first-principles swarm-intelligence based structure searches. It is found that Mn doping has significantly modified the grow behaviors of B clusters, leading to two novel structural transitions from planar to tubular and then to cage-like B structures in both neutral and charged species. Half-sandwich-type structures are most favorable for small \\text{MnB}n-/0/+ (n  ⩽  13) clusters and gradually transform to Mn-centered double-ring tubular structures at \\text{MnB}16-/0/+ clusters with superior thermodynamic stabilities compared with their neighbors. Most strikingly, endohedral cages become the ground-state structures for larger \\text{MnB}n-/0/+ (n  ⩾  19) clusters, among which \\text{MnB}20+ adopts a highly symmetric structure with superior thermodynamic stability and a large HOMO-LUMO gap of 4.53 eV. The unique stability of the endohedral \\text{MnB}\\text{20}+ cage is attributed to the geometric fit and formation of 18-electron closed-shell configuration. The results significantly advance our understanding about the structure and bonding of B-based clusters and strongly suggest transition-metal doping as a viable route to synthesize intriguing B-based nanomaterials.

Vapor deposition of water on graphitic surfaces: formation of amorphous ice, bilayer ice, ice I, and liquid water.

PubMed

Lupi, Laura; Kastelowitz, Noah; Molinero, Valeria

2014-11-14

Carbonaceous surfaces are a major source of atmospheric particles and could play an important role in the formation of ice. Here we investigate through molecular simulations the stability, metastability, and molecular pathways of deposition of amorphous ice, bilayer ice, and ice I from water vapor on graphitic and atomless Lennard-Jones surfaces as a function of temperature. We find that bilayer ice is the most stable ice polymorph for small cluster sizes, nevertheless it can grow metastable well above its region of thermodynamic stability. In agreement with experiments, the simulations predict that on increasing temperature the outcome of water deposition is amorphous ice, bilayer ice, ice I, and liquid water. The deposition nucleation of bilayer ice and ice I is preceded by the formation of small liquid clusters, which have two wetting states: bilayer pancake-like (wetting) at small cluster size and droplet-like (non-wetting) at larger cluster size. The wetting state of liquid clusters determines which ice polymorph is nucleated: bilayer ice nucleates from wetting bilayer liquid clusters and ice I from non-wetting liquid clusters. The maximum temperature for nucleation of bilayer ice on flat surfaces, T(B)(max) is given by the maximum temperature for which liquid water clusters reach the equilibrium melting line of bilayer ice as wetting bilayer clusters. Increasing water-surface attraction stabilizes the pancake-like wetting state of liquid clusters leading to larger T(B)(max) for the flat non-hydrogen bonding surfaces of this study. The findings of this study should be of relevance for the understanding of ice formation by deposition mode on carbonaceous atmospheric particles, including soot.

A Comparison of Heuristic Procedures for Minimum within-Cluster Sums of Squares Partitioning

ERIC Educational Resources Information Center

Brusco, Michael J.; Steinley, Douglas

2007-01-01

Perhaps the most common criterion for partitioning a data set is the minimization of the within-cluster sums of squared deviation from cluster centroids. Although optimal solution procedures for within-cluster sums of squares (WCSS) partitioning are computationally feasible for small data sets, heuristic procedures are required for most practical…

Why do gallium clusters have a higher melting point than the bulk?

PubMed

Chacko, S; Joshi, Kavita; Kanhere, D G; Blundell, S A

2004-04-02

Density functional molecular dynamical simulations have been performed on Ga17 and Ga13 clusters to understand the recently observed higher-than-bulk melting temperatures in small gallium clusters [Phys. Rev. Lett. 91, 215508 (2003)

Lung transplantation and interstitial lung disease.

PubMed

Alalawi, Raed; Whelan, Timothy; Bajwa, Ravinder S; Hodges, Tony N

2005-09-01

Interstitial lung disease includes a heterogeneous group of disorders that leads to respiratory insufficiency and death in a significant number of patients. Lung transplantation is a therapeutic option in select candidates. The indications, transplant procedure options, and outcomes continue to evolve. Various recipient comorbidities influence the choice of procedure in patients with interstitial lung disease. Single lung transplants are used as the procedure of choice and bilateral transplants are reserved for patients with suppurative lung disease and patients with pulmonary hypertension. Issues unique to patients with interstitial lung disease affect the morbidity, mortality and recurrence of the disease. Lung transplantation is an effective therapy for respiratory failure in interstitial lung disease with survival following transplant being similar to that achieved in transplant recipients with other diseases.

Irradiation-induced microchemical changes in highly irradiated 316 stainless steel

NASA Astrophysics Data System (ADS)

Fujii, K.; Fukuya, K.

2016-02-01

Cold-worked 316 stainless steel specimens irradiated to 74 dpa in a pressurized water reactor (PWR) were analyzed by atom probe tomography (APT) to extend knowledge of solute clusters and segregation at higher doses. The analyses confirmed that those clusters mainly enriched in Ni-Si or Ni-Si-Mn were formed at high number density. The clusters were divided into three types based on their size and Mn content; small Ni-Si clusters (3-4 nm in diameter), and large Ni-Si and Ni-Si-Mn clusters (8-10 nm in diameter). The total cluster number density was 7.7 × 1023 m-3. The fraction of large clusters was almost 1/10 of the total density. The average composition (in at%) for small clusters was: Fe, 54; Cr, 12; Mn, 1; Ni, 22; Si, 11; Mo, 1, and for large clusters it was: Fe, 44; Cr, 9; Mn, 2; Ni, 29; Si, 14; Mo,1. It was likely that some of the Ni-Si clusters correspond to γ‧ phase precipitates while the Ni-Si-Mn clusters were precursors of G phase precipitates. The APT analyses at grain boundaries confirmed enrichment of Ni, Si, P and Cu and depletion of Fe, Cr, Mo and Mn. The segregation behavior was consistent with previous knowledge of radiation induced segregation.

Development of small scale cluster computer for numerical analysis

NASA Astrophysics Data System (ADS)

Zulkifli, N. H. N.; Sapit, A.; Mohammed, A. N.

2017-09-01

In this study, two units of personal computer were successfully networked together to form a small scale cluster. Each of the processor involved are multicore processor which has four cores in it, thus made this cluster to have eight processors. Here, the cluster incorporate Ubuntu 14.04 LINUX environment with MPI implementation (MPICH2). Two main tests were conducted in order to test the cluster, which is communication test and performance test. The communication test was done to make sure that the computers are able to pass the required information without any problem and were done by using simple MPI Hello Program where the program written in C language. Additional, performance test was also done to prove that this cluster calculation performance is much better than single CPU computer. In this performance test, four tests were done by running the same code by using single node, 2 processors, 4 processors, and 8 processors. The result shows that with additional processors, the time required to solve the problem decrease. Time required for the calculation shorten to half when we double the processors. To conclude, we successfully develop a small scale cluster computer using common hardware which capable of higher computing power when compare to single CPU processor, and this can be beneficial for research that require high computing power especially numerical analysis such as finite element analysis, computational fluid dynamics, and computational physics analysis.

Electronic structures and thermochemical properties of the small silicon-doped boron clusters B(n)Si (n=1-7) and their anions.

PubMed

Tai, Truong Ba; Kadłubański, Paweł; Roszak, Szczepan; Majumdar, Devashis; Leszczynski, Jerzy; Nguyen, Minh Tho

2011-11-18

We perform a systematic investigation on small silicon-doped boron clusters B(n)Si (n=1-7) in both neutral and anionic states using density functional (DFT) and coupled-cluster (CCSD(T)) theories. The global minima of these B(n)Si(0/-) clusters are characterized together with their growth mechanisms. The planar structures are dominant for small B(n)Si clusters with n≤5. The B(6)Si molecule represents a geometrical transition with a quasi-planar geometry, and the first 3D global minimum is found for the B(7)Si cluster. The small neutral B(n)Si clusters can be formed by substituting the single boron atom of B(n+1) by silicon. The Si atom prefers the external position of the skeleton and tends to form bonds with its two neighboring B atoms. The larger B(7)Si cluster is constructed by doping Si-atoms on the symmetry axis of the B(n) host, which leads to the bonding of the silicon to the ring boron atoms through a number of hyper-coordination. Calculations of the thermochemical properties of B(n)Si(0/-) clusters, such as binding energies (BE), heats of formation at 0 K (ΔH(f)(0)) and 298 K (ΔH(f)([298])), adiabatic (ADE) and vertical (VDE) detachment energies, and dissociation energies (D(e)), are performed using the high accuracy G4 and complete basis-set extrapolation (CCSD(T)/CBS) approaches. The differences of heats of formation (at 0 K) between the G4 and CBS approaches for the B(n)Si clusters vary in the range of 0.0-4.6 kcal mol(-1). The largest difference between two approaches for ADE values is 0.15 eV. Our theoretical predictions also indicate that the species B(2)Si, B(4)Si, B(3)Si(-) and B(7)Si(-) are systems with enhanced stability, exhibiting each a double (σ and π) aromaticity. B(5)Si(-) and B(6)Si are doubly antiaromatic (σ and π) with lower stability. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Self-optimized construction of transition rate matrices from accelerated atomistic simulations with Bayesian uncertainty quantification

NASA Astrophysics Data System (ADS)

Swinburne, Thomas D.; Perez, Danny

2018-05-01

A massively parallel method to build large transition rate matrices from temperature-accelerated molecular dynamics trajectories is presented. Bayesian Markov model analysis is used to estimate the expected residence time in the known state space, providing crucial uncertainty quantification for higher-scale simulation schemes such as kinetic Monte Carlo or cluster dynamics. The estimators are additionally used to optimize where exploration is performed and the degree of temperature acceleration on the fly, giving an autonomous, optimal procedure to explore the state space of complex systems. The method is tested against exactly solvable models and used to explore the dynamics of C15 interstitial defects in iron. Our uncertainty quantification scheme allows for accurate modeling of the evolution of these defects over timescales of several seconds.

SARCOCYSTIS NEURONA-ASSOCIATED MENINGOENCEPHALITIS IN A PACIFIC WALRUS ( ODOBENDUS ROSMARUS DIVERGENS).

PubMed

Krol, Lana; Fravel, Vanessa; Procter, Diana G; Colegrove, Kathleen M

2017-12-01

A 21-yr-old intact male walrus ( Odobendus rosmarus divergens) presented with acute onset of shifting lameness, initially associated with breeding behaviors. Further clinical signs manifested, including muscle tremors, anorexia, hematuria, and coughing. Diagnostics were limited, as the animal would not offer behaviors for voluntary sample collection. Signs were addressed with anti-inflammatories, anticonvulsants, and antibiotics. The walrus developed cluster seizures and ultimately, respiratory and cardiac arrest. Postmortem lesions included meningoencephalitis with intra- and extracellular protozoal zoites and schizonts, as well as interstitial pneumonia with intraendothelial protozoa. Immunolabeling of the protozoal organisms revealed Sarcocystis neurona. Previous S. neurona infections in an odobenid have not been reported. Protozoal infection should be considered in all species of captive marine mammals with nonspecific orthopedic, neurological, and respiratory clinical signs.

Subaru Weak-Lensing Survey II: Multi-Object Spectroscopy and Cluster Masses

NASA Astrophysics Data System (ADS)

Hamana, Takashi; Miyazaki, Satoshi; Kashikawa, Nobunari; Ellis, Richard S.; Massey, Richard J.; Refregier, Alexandre; Taylor, James E.

2009-08-01

We present the first results of a multi-object spectroscopic campaign to follow up cluster candidates located via weak lensing. Our main goals are to search for spatial concentrations of galaxies that are plausible optical counterparts of the weak-lensing signals, and to determine the cluster redshifts from those of member galaxies. Around each of 36 targeted cluster candidates, we obtained 15-32 galaxy redshifts. For 28 of these targets, we confirmed a secure cluster identification, with more than five spectroscopic galaxies within a velocity of ±3000km s-1. This includes three cases where two clusters at different redshifts are projected along the same line-of-sight. In 6 of the 8 unconfirmed targets, we found multiple small galaxy concentrations at different redshifts, each containing at least three spectroscopic galaxies. The weak-lensing signal around those systems was thus probably created by the projection of groups or small clusters along the same line-of-sight. In both of the remaining two targets, a single small galaxy concentration was found. In some candidate super-cluster systems, we found additional evidence of filaments connecting the main density peak to an additional nearby structure. For a subsample of our most cleanly measured clusters, we investigated the statistical relation between their weak-lensing mass (MNFW, σSIS) and the velocity dispersion of their member galaxies (σv), comparing our sample with optically and X-ray selected samples from the literature. Our lensing-selected clusters are consistent with σv = σSIS, with a similar scatter to that of optically and X-ray selected clusters. We also derived an empirical relation between the cluster mass and the galaxy velocity dispersion, M200E(z) = 11.0 × 1014 × (σv/1000km s-1)3.0 h-1 Modot, which is in reasonable agreement with predictions of N-body simulations in the Λ CDM cosmology.

Age determination of 15 old to intermediate-age small Magellanic cloud star clusters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parisi, M. C.; Clariá, J. J.; Piatti, A. E.

2014-04-01

We present color-magnitude diagrams in the V and I bands for 15 star clusters in the Small Magellanic Cloud (SMC) based on data taken with the Very Large Telescope (VLT, Chile). We selected these clusters from our previous work, wherein we derived cluster radial velocities and metallicities from calcium II infrared triplet (CaT) spectra also taken with the VLT. We discovered that the ages of six of our clusters have been appreciably underestimated by previous studies, which used comparatively small telescopes, graphically illustrating the need for large apertures to obtain reliable ages of old and intermediate-age SMC star clusters. Inmore » particular, three of these clusters, L4, L6, and L110, turn out to be among the oldest SMC clusters known, with ages of 7.9 ± 1.1, 8.7 ± 1.2, and 7.6 ± 1.0 Gyr, respectively, helping to fill a possible 'SMC cluster age gap'. Using the current ages and metallicities from Parisi et al., we analyze the age distribution, age gradient, and age-metallicity relation (AMR) of a sample of SMC clusters measured homogeneously. There is a suggestion of bimodality in the age distribution but it does not show a constant slope for the first 4 Gyr, and we find no evidence for an age gradient. Due to the improved ages of our cluster sample, we find that our AMR is now better represented in the intermediate/old period than we had derived in Parisi et al., where we simply took ages available in the literature. Additionally, clusters younger than ∼4 Gyr now show better agreement with the bursting model of Pagel and Tautvaišienė, but we confirm that this model is not a good representation of the AMR during the intermediate/old period. A more complicated model is needed to explain the SMC chemical evolution in that period.« less

Therapeutic Targeting of CC Ligand 21 or CC Chemokine Receptor 7 Abrogates Pulmonary Fibrosis Induced by the Adoptive Transfer of Human Pulmonary Fibroblasts to Immunodeficient Mice

PubMed Central

Pierce, Elizabeth M.; Carpenter, Kristin; Jakubzick, Claudia; Kunkel, Steven L.; Flaherty, Kevin R.; Martinez, Fernando J.; Hogaboam, Cory M.

2007-01-01

Idiopathic interstitial pneumonias (IIPs) are a collection of pulmonary fibrotic diseases of unknown etiopathogenesis. CC chemokine receptor 7 (CCR7) is expressed in IIP biopsies and primary fibroblast lines, but its role in pulmonary fibrosis was not previously examined. To study the in vivo role of CCR7 in a novel model of pulmonary fibrosis, 1.0 × 106 primary fibroblasts grown from idiopathic pulmonary fibrosis/usual interstitial pneumonia, nonspecific interstitial pneumonia, or histologically normal biopsies were injected intravenously into C.B-17 severe combined immunodeficiency (SCID)/beige (bg) mice. At days 35 and 63 after idiopathic pulmonary fibrosis/usual interstitial pneumonia fibroblast injection, patchy interstitial fibrosis and increased hydroxyproline were present in the lungs of immunodeficient mice. Adoptively transferred nonspecific interstitial pneumonia fibroblasts caused a more diffuse interstitial fibrosis and increased hydroxyproline levels at both times, but injected normal human fibroblasts did not induce interstitial remodeling changes in C.B-17SCID/bg mice. Systemic therapeutic immunoneutralization of either human CCR7 or CC ligand 21, its ligand, significantly attenuated the pulmonary fibrosis in groups of C.B-17SCID/bg mice that received either type of IIP fibroblasts. Thus, the present study demonstrates that pulmonary fibrosis is initiated by the intravenous introduction of primary human fibroblast lines into immunodeficient mice, and this fibrotic response is dependent on the interaction between CC ligand 21 and CCR7. PMID:17392156

Shield fields: Concentrations of small volcanic edifices on Venus

NASA Technical Reports Server (NTRS)

Aubele, J. C.; Crumpler, L. S.

1992-01-01

Pre-Magellan analysis of the Venera 15/16 data indicated the existence of abundant small volcanic edifices, each less than or equal to 20 km diameter, interpreted to be predominantly shield volcanoes and occurring throughout the plains terrain, most common in equidimensional clusters. With the analysis of Magellan data, these clusters of greater than average concentration of small volcanic edifices have been called 'shield fields'. Although individual small shields can and do occur almost everywhere on the plains terrain of Venus, they most commonly occur in fields that are well-defined, predominantly equant, clusters of edifices. Major questions include why the edifices are concentrated in this way, how they relate to the source of the eruptive material, and what the possible relationship of shield fields to plains terrain is. There are three possible models for the origin of fields and small shields: (1) a field represents an 'island' of higher topography subsequently surrounded by later plains material; and (2) a field represents the area of magma reservoir.

Hydrogen bonding interaction of small acetaldehyde clusters studied with core-electron excitation spectroscopy in the oxygen K-edge region

NASA Astrophysics Data System (ADS)

Tabayashi, K.; Chohda, M.; Yamanaka, T.; Tsutsumi, Y.; Takahashi, O.; Yoshida, H.; Taniguchi, M.

2010-06-01

In order to examine inner-shell electron excitation spectra of molecular clusters with strong multipole interactions, excitation spectra and time-of-flight (TOF) fragment-mass spectra of small acetaldehyde (AA) clusters have been studied under the beam conditions. The TOF spectra at the oxygen K-edge region showed an intense growth of the protonated clusters, MnH+ (M=CH3CHO) in the cluster beams. "cluster-specific" excitation spectra could be generated by monitoring partial-ion-yields of the protonated clusters. The most intense band of O1s→π*CO was found to shift to a higher energy by 0.15 eV relative to the monomer band upon clusterization. X-ray absorption spectra (XAS) were also calculated for the representative dimer configurations using a computer modelling program based on the density functional theory. The XAS prediction for the most stable (non-planar) configuration was found to give a close comparison with the cluster-band shift observed. The band shift was interpreted as being due to the HOMO-LUMO interaction within the complex where a contribution of vibrationally blue-shifting hydrogen bonding could be identified.

Ab initio calculations of optical properties of silver clusters: cross-over from molecular to nanoscale behavior

NASA Astrophysics Data System (ADS)

Titantah, John T.; Karttunen, Mikko

2016-05-01

Electronic and optical properties of silver clusters were calculated using two different ab initio approaches: (1) based on all-electron full-potential linearized-augmented plane-wave method and (2) local basis function pseudopotential approach. Agreement is found between the two methods for small and intermediate sized clusters for which the former method is limited due to its all-electron formulation. The latter, due to non-periodic boundary conditions, is the more natural approach to simulate small clusters. The effect of cluster size is then explored using the local basis function approach. We find that as the cluster size increases, the electronic structure undergoes a transition from molecular behavior to nanoparticle behavior at a cluster size of 140 atoms (diameter ~1.7 nm). Above this cluster size the step-like electronic structure, evident as several features in the imaginary part of the polarizability of all clusters smaller than Ag147, gives way to a dominant plasmon peak localized at wavelengths 350 nm ≤ λ ≤ 600 nm. It is, thus, at this length-scale that the conduction electrons' collective oscillations that are responsible for plasmonic resonances begin to dominate the opto-electronic properties of silver nanoclusters.

Mitochondrial filaments and clusters as intracellular power-transmitting cables.

PubMed

Skulachev, V P

2001-01-01

Mitochondria exist in two interconverting forms; as small isolated particles, and as extended filaments, networks or clusters connected with intermitochondrial junctions. Extended mitochondria can represent electrically united systems, which can facilitate energy delivery from the cell periphery to the cell core and organize antioxidant defence of the cell interior when O2 is consumed by mitochondrial clusters near the the outer cell membrane, and protonic potential is transmitted to the cell core mitochondria to form ATP. As to small mitochondria, they might represent a transportable form of these organelles.

Focal Solute Trapping and Global Glymphatic Pathway Impairment in a Murine Model of Multiple Microinfarcts

PubMed Central

Wang, Minghuan; Ding, Fengfei; Deng, SaiYue; Guo, Xuequn; Wang, Wei

2017-01-01

Microinfarcts occur commonly in the aging brain as a consequence of diffuse embolic events and are associated with the development of vascular dementia and Alzheimer's disease. However, the manner in which disperse microscopic lesions reduce global cognitive function and increase the risk for Alzheimer's disease is unclear. The glymphatic system, which is a brain-wide perivascular network that supports the recirculation of CSF through the brain parenchyma, facilitates the clearance of interstitial solutes including amyloid β and tau. We investigated whether glymphatic pathway function is impaired in a murine model of multiple microinfarcts induced by intraarterial injection of cholesterol crystals. The analysis showed that multiple microinfarcts markedly impaired global influx of CSF along the glymphatic pathway. Although suppression of global glymphatic function was transient, resolving within 2 weeks of injury, CSF tracers also accumulated within tissue associated with microinfarcts. The effect of diffuse microinfarcts on global glymphatic pathway function was exacerbated in the mice aged 12 months compared with the 2- to 3-month-old mice. These findings indicate that glymphatic function is focally disrupted around microinfarcts and that the aging brain is more vulnerable to this disruption than the young brain. These observations suggest that microlesions may trap proteins and other interstitial solutes within the brain parenchyma, increasing the risk of amyloid plaque formation. SIGNIFICANCE STATEMENT Microinfarcts, small (<1 mm) ischemic lesions, are strongly associated with age-related dementia. However, how these microscopic lesions affect global cognitive function and predispose to Alzheimer's disease is unclear. The glymphatic system is a brain-wide network of channels surrounding brain blood vessels that allows CSF to exchange with interstitial fluid, clearing away cellular wastes such as amyloid β. We observed that, in mice, microinfarcts impaired global glymphatic function and solutes from the CSF became trapped in tissue associated with microinfarcts. These data suggest that small, disperse ischemic lesions can impair glymphatic function across the brain and trapping of solutes in these lesions may promote protein aggregation and neuroinflammation and eventually lead to neurodegeneration, especially in the aging brain. PMID:28188218

Focal Solute Trapping and Global Glymphatic Pathway Impairment in a Murine Model of Multiple Microinfarcts.

PubMed

Wang, Minghuan; Ding, Fengfei; Deng, SaiYue; Guo, Xuequn; Wang, Wei; Iliff, Jeffrey J; Nedergaard, Maiken

2017-03-15

Microinfarcts occur commonly in the aging brain as a consequence of diffuse embolic events and are associated with the development of vascular dementia and Alzheimer's disease. However, the manner in which disperse microscopic lesions reduce global cognitive function and increase the risk for Alzheimer's disease is unclear. The glymphatic system, which is a brain-wide perivascular network that supports the recirculation of CSF through the brain parenchyma, facilitates the clearance of interstitial solutes including amyloid β and tau. We investigated whether glymphatic pathway function is impaired in a murine model of multiple microinfarcts induced by intraarterial injection of cholesterol crystals. The analysis showed that multiple microinfarcts markedly impaired global influx of CSF along the glymphatic pathway. Although suppression of global glymphatic function was transient, resolving within 2 weeks of injury, CSF tracers also accumulated within tissue associated with microinfarcts. The effect of diffuse microinfarcts on global glymphatic pathway function was exacerbated in the mice aged 12 months compared with the 2- to 3-month-old mice. These findings indicate that glymphatic function is focally disrupted around microinfarcts and that the aging brain is more vulnerable to this disruption than the young brain. These observations suggest that microlesions may trap proteins and other interstitial solutes within the brain parenchyma, increasing the risk of amyloid plaque formation. SIGNIFICANCE STATEMENT Microinfarcts, small (<1 mm) ischemic lesions, are strongly associated with age-related dementia. However, how these microscopic lesions affect global cognitive function and predispose to Alzheimer's disease is unclear. The glymphatic system is a brain-wide network of channels surrounding brain blood vessels that allows CSF to exchange with interstitial fluid, clearing away cellular wastes such as amyloid β. We observed that, in mice, microinfarcts impaired global glymphatic function and solutes from the CSF became trapped in tissue associated with microinfarcts. These data suggest that small, disperse ischemic lesions can impair glymphatic function across the brain and trapping of solutes in these lesions may promote protein aggregation and neuroinflammation and eventually lead to neurodegeneration, especially in the aging brain. Copyright © 2017 the authors 0270-6474/17/372870-08$15.00/0.

Comparisons of fish species traits from small streams to large rivers

USGS Publications Warehouse

Goldstein, R.M.; Meador, M.R.

2004-01-01

To examine the relations between fish community function and stream size, we classified 429 lotic freshwater fish species based on multiple categories within six species traits: (1) substrate preference, (2) geomorphic preference, (3) trophic ecology, (4) locomotion morphology, (5) reproductive strategy, and (6) stream size preference. Stream size categories included small streams, small, medium, and large rivers, and no size preference. The frequencies of each species trait category were determined for each stream size category based on life history information from the literature. Cluster analysis revealed the presence of covarying groups of species trait categories. One cluster (RUN) included the traits of planktivore and herbivore feeding ecology, migratory reproductive behavior and broadcast spawning, preferences for main-channel habitats, and a lack of preferences for substrate type. The frequencies of classifications for the RUN cluster varied significantly across stream size categories (P = 0.009), being greater for large rivers than for small streams and rivers. Another cluster (RIFFLE) included the traits of invertivore feeding ecology, simple nester reproductive behavior, a preference for riffles, and a preference for bedrock, boulder, and cobble-rubble substrate. No significant differences in the frequency of classifications among stream size categories were detected for the RIFFLE cluster (P = 0.328). Our results suggest that fish community function is structured by large-scale differences in habitat and is different for large rivers than for small streams and rivers. Our findings support theoretical predictions of variation in species traits among stream reaches based on ecological frameworks such as landscape filters, habitat templates, and the river continuum concept. We believe that the species trait classifications presented here provide an opportunity for further examination of fish species' relations to physical, chemical, and biological factors in lotic habitats ranging from small streams to large rivers.

Predicting the points of interaction of small molecules in the NF-κB pathway

PubMed Central

2011-01-01

Background The similarity property principle has been used extensively in drug discovery to identify small compounds that interact with specific drug targets. Here we show it can be applied to identify the interactions of small molecules within the NF-κB signalling pathway. Results Clusters that contain compounds with a predominant interaction within the pathway were created, which were then used to predict the interaction of compounds not included in the clustering analysis. Conclusions The technique successfully predicted the points of interactions of compounds that are known to interact with the NF-κB pathway. The method was also shown to be successful when compounds for which the interaction points were unknown were included in the clustering analysis. PMID:21342508

Dysregulated Functions of Lung Macrophage Populations in COPD.

PubMed

Kapellos, Theodore S; Bassler, Kevin; Aschenbrenner, Anna C; Fujii, Wataru; Schultze, Joachim L

2018-01-01

Chronic obstructive pulmonary disease (COPD) is a diverse respiratory disease characterised by bronchiolitis, small airway obstruction, and emphysema. Innate immune cells play a pivotal role in the disease's progression, and in particular, lung macrophages exploit their prevalence and strategic localisation to orchestrate immune responses. To date, alveolar and interstitial resident macrophages as well as blood monocytes have been described in the lungs of patients with COPD contributing to disease pathology by changes in their functional repertoire. In this review, we summarise recent evidence from human studies and work with animal models of COPD with regard to altered functions of each of these myeloid cell populations. We primarily focus on the dysregulated capacity of alveolar macrophages to secrete proinflammatory mediators and proteases, induce oxidative stress, engulf microbes and apoptotic cells, and express surface and intracellular markers in patients with COPD. In addition, we discuss the differences in the responses between alveolar macrophages and interstitial macrophages/monocytes in the disease and propose how the field should advance to better understand the implications of lung macrophage functions in COPD.

Adherence of Myxobolus cerebralis myxospores to waders: Implications for disease dissemination

USGS Publications Warehouse

Gates, K.K.; Guy, C.S.; Zale, A.V.; Horton, T.B.

2008-01-01

The vectors involved in the spread of whirling disease, which is caused by Myxobolus cerebralis, are only partly understood. However, the parasite has rapidly become established in many regions, suggesting that it is easily disseminated. We gained insight into transport vectors by examining the surface porosity of common wading equipment materials and the adherence of M. cerebralis myxospores to them. Interstitial spaces within rubber, felt, lightweight nylon, and neoprene were measured on scanning electron microscope images. Myxospores were applied to each material, the material was rinsed, and the myxospores recovered to assess adherence. The mean interstitial space size of rubber was the smallest (2.0 ??m), whereas that of felt was the largest (31.3 ??m). The highest recovery rates were from rubber and the glass control. Percent myxospore recovery varied by material, the recovery from felt being lower than that from all other materials. The potential for felt to carry even small numbers of myxospores suggests that the introduction of M. cerebralis by felt-soled wading boots is possible. ?? Copyright by the American Fisheries Society 2008.

Normal expiratory flow rate and lung volumes in patients with combined emphysema and interstitial lung disease: a case series and literature review.

PubMed

Heathcote, Karen L; Cockcroft, Donald W; Fladeland, Derek A; Fenton, Mark E

2011-01-01

Pulmonary function tests in patients with idiopathic pulmonary fibrosis characteristically show a restrictive pattern including small lung volumes and increased expiratory flow rates resulting from a reduction in pulmonary compliance due to diffuse fibrosis. Conversely, an obstructive pattern with hyperinflation results in emphysema by loss of elastic recoil, expiratory collapse of the peripheral airways and air trapping. When the diseases coexist, pulmonary volumes are compensated, and a smaller than expected reduction or even normal lung volumes can be found. The present report describes 10 patients with progressive breathlessness, three of whom experienced severe limitation in their quality of life. All patients showed lung interstitial involvement and emphysema on computed tomography scan of the chest. The 10 patients showed normal spirometry and lung volumes with severe compromise of gas exchange. Normal lung volumes do not exclude diagnosis of idiopathic pulmonary fibrosis in patients with concomitant emphysema. The relatively preserved lung volumes may underestimate the severity of idiopathic pulmonary fibrosis and attenuate its effects on lung function parameters.

The irradiation-induced microstructural development and the role of γ' on void formation in Ni-based alloys

NASA Astrophysics Data System (ADS)

Kato, Takahiko; Nakata, Kiyotomo; Masaoka, Isao; Takahashi, Heishichiro; Takeyama, Taro; Ohnuki, Soumei; Osanai, Hisashi

1984-05-01

The microstructural development for Inconel X-750, N1-13 at%A1, and Ni-11.5 at%Si alloys during irradiation was investigated. These alloys were previously heat-treated at temperatures of 723-1073 K, and γ' precipitates were produced. Irradiation was performed in a high voltage electron microscope (1000 kV) in the temperature range 673-823 K. In the case of solution-treated Inconel, interstitial dislocation loops were formed initially, while voids were nucleated after longer times. When the Inconel specimen containing a high number density of small γ' was irradiated, dislocation loops were formed in both the matrix and precipitate-matrix interface. The loops formed on the interface scarcely grew during irradiation. On the other hand, for the Ni-Al alloy fine γ' nucleated during irradiation, the large γ' precipitated by pre-aging, dissolved. A similar resolution process was also observed in Ni-Si alloy. Furthermore, in the Ni-Si alloy precipitates of γ' formed preferentially at interstitial dislocation loops and both specimen surfaces.

Dysregulated Functions of Lung Macrophage Populations in COPD

PubMed Central

Bassler, Kevin; Aschenbrenner, Anna C.

2018-01-01

Chronic obstructive pulmonary disease (COPD) is a diverse respiratory disease characterised by bronchiolitis, small airway obstruction, and emphysema. Innate immune cells play a pivotal role in the disease's progression, and in particular, lung macrophages exploit their prevalence and strategic localisation to orchestrate immune responses. To date, alveolar and interstitial resident macrophages as well as blood monocytes have been described in the lungs of patients with COPD contributing to disease pathology by changes in their functional repertoire. In this review, we summarise recent evidence from human studies and work with animal models of COPD with regard to altered functions of each of these myeloid cell populations. We primarily focus on the dysregulated capacity of alveolar macrophages to secrete proinflammatory mediators and proteases, induce oxidative stress, engulf microbes and apoptotic cells, and express surface and intracellular markers in patients with COPD. In addition, we discuss the differences in the responses between alveolar macrophages and interstitial macrophages/monocytes in the disease and propose how the field should advance to better understand the implications of lung macrophage functions in COPD. PMID:29670919

Involvement of mitochondrial Na+–Ca2+ exchange in intestinal pacemaking activity

PubMed Central

Kim, Byung Joo; Jun, Jae Yeoul; So, Insuk; Kim, Ki Whan

2006-01-01

AIM: Interstitial cells of Cajal (ICCs) are the pacemaker cells that generate slow waves in the gastrointestinal (GI) tract. We have aimed to investigate the involvement of mitochondrial Na+-Ca2+ exchange in intestinal pacemaking activity in cultured interstitial cells of Cajal. METHODS: Enzymatic digestions were used to dissociate ICCs from the small intestine of a mouse. The whole-cell patch-clamp configuration was used to record membrane currents (voltage clamp) and potentials (current clamp) from cultured ICCs. RESULTS: Clonazepam and CGP37157 inhibited the pacemaking activity of ICCs in a dose-dependent manner. Clonazepam from 20 to 60 µmol/L and CGP37157 from 10 to 30 µmol/L effectively inhibited Ca2+ efflux from mitochondria in pacemaking activity of ICCs. The IC50s of clonazepam and CGP37157 were 37.1 and 18.2 µmol/L, respectively. The addition of 20 µmol/L NiCl2 to the internal solution caused a “wax and wane” phenomenon of pacemaking activity of ICCs. CONCLUSION: These results suggest that mitochondrial Na+-Ca2+ exchange has an important role in intestinal pacemaking activity. PMID:16521198

Effects of ionization radiation on BICMOS components for space application

NASA Astrophysics Data System (ADS)

Rancoita, P. G.; Croitoru, N.; D'Angelo, P.; de Marchi, M.; Favalli, A.; Seidman, A.; Colder, A.; Levalois, M.; Marie, P.; Fallica, G.; Leonardi, S.; Modica, R.

2002-12-01

In this paper experimental results on radiation effects on a BICMOS high-speed standard commercial technology, manufactured by ST-Microelectronics, are reported. Bipolar transistors were irradiated by neutrons, ions, or by both of them. Fast neutrons, as well as other types of particles, produce defects, mainly by displacing silicon atoms from their lattice positions to interstitial locations, i.e. generating vacancy-interstitial pairs, the so-called Frenkel pairs. Defects introduce trapping energy states which degrade the common emitter current gain . The gain degradation has bee investigated for collector current, Ic, between 1 μA and1 mA. It was found a linear dependence of Δ(1/β) = 1/β- 1/βi(where βi and β are the gain after and before tirradiation) as a function of the concentration of Frenkel pairs. The bipolar transistors made on this technology have shown to be particularly radiation resistant. For instance, npn small area transistors have a gain variation (-i)/, lower than 10% for doses of about 0.5 MRad and collector currents of 1 μA, well suited for low power consumption space application

Cluster-specific small airway modeling for imaging-based CFD analysis of pulmonary air flow and particle deposition in COPD smokers

NASA Astrophysics Data System (ADS)

Haghighi, Babak; Choi, Jiwoong; Choi, Sanghun; Hoffman, Eric A.; Lin, Ching-Long

2017-11-01

Accurate modeling of small airway diameters in patients with chronic obstructive pulmonary disease (COPD) is a crucial step toward patient-specific CFD simulations of regional airflow and particle transport. We proposed to use computed tomography (CT) imaging-based cluster membership to identify structural characteristics of airways in each cluster and use them to develop cluster-specific airway diameter models. We analyzed 284 COPD smokers with airflow limitation, and 69 healthy controls. We used multiscale imaging-based cluster analysis (MICA) to classify smokers into 4 clusters. With representative cluster patients and healthy controls, we performed multiple regressions to quantify variation of airway diameters by generation as well as by cluster. The cluster 2 and 4 showed more diameter decrease as generation increases than other clusters. The cluster 4 had more rapid decreases of airway diameters in the upper lobes, while cluster 2 in the lower lobes. We then used these regression models to estimate airway diameters in CT unresolved regions to obtain pressure-volume hysteresis curves using a 1D resistance model. These 1D flow solutions can be used to provide the patient-specific boundary conditions for 3D CFD simulations in COPD patients. Support for this study was provided, in part, by NIH Grants U01-HL114494, R01-HL112986 and S10-RR022421.

Effect of electron injection on defect reactions in irradiated silicon containing boron, carbon, and oxygen

NASA Astrophysics Data System (ADS)

Makarenko, L. F.; Lastovskii, S. B.; Yakushevich, H. S.; Moll, M.; Pintilie, I.

2018-04-01

Comparative studies employing Deep Level Transient Spectroscopy and C-V measurements have been performed on recombination-enhanced reactions between defects of interstitial type in boron doped silicon diodes irradiated with alpha-particles. It has been shown that self-interstitial related defects which are immobile even at room temperatures can be activated by very low forward currents at liquid nitrogen temperatures. Their activation is accompanied by the appearance of interstitial carbon atoms. It has been found that at rather high forward current densities which enhance BiOi complex disappearance, a retardation of Ci annealing takes place. Contrary to conventional thermal annealing of the interstitial boron-interstitial oxygen complex, the use of forward current injection helps to recover an essential part of charge carriers removed due to irradiation.

Interstitial protein alterations in rabbit vocal fold with scar.

PubMed

Thibeault, Susan L; Bless, Diane M; Gray, Steven D

2003-09-01

Fibrous and interstitial proteins compose the extracellular matrix of the vocal fold lamina propria and account for its biomechanic properties. Vocal fold scarring is characterized by altered biomechanical properties, which create dysphonia. Although alterations of the fibrous proteins have been confirmed in the rabbit vocal fold scar, interstitial proteins, which are known to be important in wound repair, have not been investigated to date. Using a rabbit model, interstitial proteins decorin, fibromodulin, and fibronectin were examined immunohistologically, two months postinduction of vocal fold scar by means of forcep biopsy. Significantly decreased decorin and fibromodulin with significantly increased fibronectin characterized scarred vocal fold tissue. The implications of altered interstitial proteins levels and their affect on the fibrous proteins will be discussed in relation to increased vocal fold stiffness and viscosity, which characterizes vocal fold scar.

CT in the diagnosis of interstitial lung disease

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bergin, C.J.; Mueller, N.L.

1985-09-01

The computed tomographic (CT) appearance of interstitial lung disease was assessed in 23 patients with known interstitial disease. These included seven patients with fibrosing alveolitis, six with silicosis, two with hypersensitivity pneumonitis, three with lymphangitic spread of tumor, two with sarcoidosis, one with rheumatoid lung disease, and two with neurofibromatosis. The CT appearance of the interstitial changes in the different disease entities was assessed. Nodules were a prominent CT feature in silicosis, sarcoidosis, and lymphangitic spread of malignancy. Distribution of nodules and associated interlobular septal thickening provided further distinguishing features in these diseases. Reticular densities were the predominant CT changemore » in fibrosing alveolitis, rheumatoid lung disease, and extrinsic allergic alveolitis. CT can be useful in the investigation of selected instances of interstitial pulmonary disease.« less

Application of Scan Statistics to Detect Suicide Clusters in Australia

PubMed Central

Cheung, Yee Tak Derek; Spittal, Matthew J.; Williamson, Michelle Kate; Tung, Sui Jay; Pirkis, Jane

2013-01-01

Background Suicide clustering occurs when multiple suicide incidents take place in a small area or/and within a short period of time. In spite of the multi-national research attention and particular efforts in preparing guidelines for tackling suicide clusters, the broader picture of epidemiology of suicide clustering remains unclear. This study aimed to develop techniques in using scan statistics to detect clusters, with the detection of suicide clusters in Australia as example. Methods and Findings Scan statistics was applied to detect clusters among suicides occurring between 2004 and 2008. Manipulation of parameter settings and change of area for scan statistics were performed to remedy shortcomings in existing methods. In total, 243 suicides out of 10,176 (2.4%) were identified as belonging to 15 suicide clusters. These clusters were mainly located in the Northern Territory, the northern part of Western Australia, and the northern part of Queensland. Among the 15 clusters, 4 (26.7%) were detected by both national and state cluster detections, 8 (53.3%) were only detected by the state cluster detection, and 3 (20%) were only detected by the national cluster detection. Conclusions These findings illustrate that the majority of spatial-temporal clusters of suicide were located in the inland northern areas, with socio-economic deprivation and higher proportions of indigenous people. Discrepancies between national and state/territory cluster detection by scan statistics were due to the contrast of the underlying suicide rates across states/territories. Performing both small-area and large-area analyses, and applying multiple parameter settings may yield the maximum benefits for exploring clusters. PMID:23342098

Respiratory herpesvirus infection in two Indian Ringneck parakeets.

PubMed

Lazic, Tatjana; Ackermann, Mark R; Drahos, Jo M; Stasko, Judith; Haynes, Joseph S

2008-03-01

A flock of Indian Ringneck parakeets (Psittacula krameri manillensis) was imported to the United States from Australia. Soon after, 1 parakeet suddenly died, and a second parakeet died after a 2-day course of illness, which consisted of anorexia, lethargy, emaciation, and dyspnea. At necropsy, the affected birds had diffuse consolidation and red discoloration of the lungs, as well as thickened, congested air sacs. The microscopic examination revealed multifocal, necrotizing bronchitis, parabronchitis, and interstitial pneumonia. The lumen of the affected airways contained numerous, large syncytial cells with up to 15 nuclei. The nuclei of these syncytial cells often contained large, eosinophilic inclusion bodies, consistent with herpesvirus. The epithelium of the trachea and air sacs was hypertrophied and contained syncytial cells with intranuclear inclusion bodies similar to the bronchi. In addition, a few intranuclear inclusion bodies were also present in the epithelial cells that line the air capillaries. On ultrastructural examination, the nuclei of degenerating epithelial cells contained clusters of viral nucleocapsid proteins and unenveloped, icosahedral, viral particles that were approximately 90 nm in diameter. In addition, some epithelial cells contained clusters of enveloped viral particles approximately 105 nm in diameter, within the cytocavitary network. These lesions are characteristic of those caused by respiratory herpesvirus of parakeets.

Stressful jobs and non-stressful jobs: a cluster analysis of office jobs.

PubMed

Carayon, P

1994-02-01

The purpose of the study was to determine if office jobs could be characterized by a small number of combinations of stressors that could be related to job-title information and self-report of psychological strain. Two-hundred-and-sixty-two office workers from three public service organizations provided data on nine job stressors and seven indicators of psychological strain. Using cluster analysis on the nine stressors, office jobs were classified into three clusters. The first cluster included jobs with high skill utilization, task clarity, job control and social support and low future ambiguity, but also high on job demands such as quantitative work-load, attention and work pressure. The second cluster included jobs with high demands and future ambiguity and low skill utilization, task clarity, job control and social support. The third cluster was intermediary between the first two clusters. The three clusters were related to job-title information. The second cluster was the highest on a range of psychological strain indicators, while the other two clusters were high on certain strain indicators but low on others. The study showed that office jobs could be characterized by a small number of combinations of stressors that were related to job-title information and psychological strain.

Towards a comprehensive knowledge of the star cluster population in the Small Magellanic Cloud

NASA Astrophysics Data System (ADS)

Piatti, A. E.

2018-07-01

The Small Magellanic Cloud (SMC) has recently been found to harbour an increase of more than 200 per cent in its known cluster population. Here, we provide solid evidence that this unprecedented number of clusters could be greatly overestimated. On the one hand, the fully automatic procedure used to identify such an enormous cluster candidate sample did not recover ˜50 per cent, on average, of the known relatively bright clusters located in the SMC main body. On the other hand, the number of new cluster candidates per time unit as a function of time is noticeably different from the intrinsic SMC cluster frequency (CF), which should not be the case if these new detections were genuine physical systems. We found additionally that the SMC CF varies spatially, in such a way that it resembles an outside-in process coupled with the effects of a relatively recent interaction with the Large Magellanic Cloud. By assuming that clusters and field stars share the same formation history, we showed for the first time that the cluster dissolution rate also depends on position in the galaxy. The cluster dissolution becomes higher as the concentration of galaxy mass increases or if external tidal forces are present.

Hunter-McAlpine craniosynostosis phenotype associated with skeletal anomalies and interstitial deletion of chromosome 17q

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thomas, J.; Prescott, K.; Milner, R.

1994-09-01

Syndromic craniosynostosis is frequently associated with skeletal abnormalities, but the biological basis for this association is unclear. Molecular genetic studies have the biological basis for this association is unclear. Molecular genetic studies have identified a number of loci and at least one candidate gene, the MSX2 gene. We recently encountered a 9 y.o. boy with moderate mental retardation, congenital craniosynostosis, and multiple skeletal anomalies. Physical features strongly suggested Hunter-McAlpine syndrome (HMS). Specifically, he had triangular facies with a small mouth prominent chin, bulbous nose, thin vermillion border, malaligned and malformed teeth, and low set, rudimentary ears. Skeletal features included: bilambdoidal,more » bicoronal, and sagittal craniosynostosis; right preaxial polydactyly; bilateral talipes; coxa valga; genu valgum; bilateral fusion of the hamate and capitate; scoliosis; and small, irregular middle phalangeal epiphyses. High resolution chromosome analysis revealed an interstitial deletion of G negative material of subbands q23.1{r_arrow}23.3 or q23.3{r_arrow}q24.2 of a No. 17 homologue. HMS, a presumed autosomal dominant disorder associated with characteristic facies, variable degrees of mental retardation, craniosynostosis, and minor acral-skeletal anomalies, proved to be the most likely explanation for this patient`s findings. We propose that our patient has a new mutation for HMS with more severe skeletal involvement than previously reported. Linkage studies are in progress to test the hypothesis that familial HMS may be localized to chromosome 17.« less

Implications of using thermocouple thermometry in 27 MHz capacitively coupled interstitial hyperthermia.

PubMed

Crezee, J; van der Koijk, J F; Kaatee, R S; Lagendijk, J J

1997-04-01

The 27 MHz Multi Electrode Current Source (MECS) interstitial hyperthermia system uses segmented electrodes, 10-20 mm long, to steer the 3D power deposition. This power control at a scale of 1-2 cm requires detailed and accurate temperature feedback data. To this end seven-point thermocouples are integrated into the probes. The aim of this work was to evaluate the feasibility and reliability of integrated thermometry in the 27 MHz MECS system, with special attention to the interference between electrode and thermometry and its effect on system performance. We investigated the impact of a seven-sensor thermocouple probe (outer diameter 150 microns) on the apparent impedance and power output of a 20 mm dual electrode (O.D. 1.5 mm) in a polyethylene catheter in a muscle equivalent medium (sigma 1 = 0.6 S m-1). The cross coupling between electrode and thermocouple was found to be small (1-2 pF) and to cause no problems in the dual-electrode mode, and only minimal problems in the single-electrode mode. Power loss into the thermometry system can be prevented using simple filters. The temperature readings are reliable and representative of the actual tissue temperature around the electrode. Self-heating effects, occurring in some catheter materials, are eliminated by sampling the temperature after a short power-off interval. We conclude that integrated thermocouple thermometry is compatible with 27 MHz capacitively coupled interstitial hyperthermia. The performance of the system is not affected and the temperatures measured are a reliable indication of the maximum tissue temperatures.

Phosphorescence quenching microrespirometry of skeletal muscle in situ

PubMed Central

Golub, Aleksander S.; Tevald, Michael A.

2011-01-01

We have developed an optical method for the evaluation of the oxygen consumption (V̇o2) in microscopic volumes of spinotrapezius muscle. Using phosphorescence quenching microscopy (PQM) for the measurement of interstitial Po2, together with rapid pneumatic compression of the organ, we recorded the oxygen disappearance curve (ODC) in the muscle of the anesthetized rats. A 0.6-mm diameter area in the tissue, preloaded with the phosphorescent oxygen probe, was excited once a second by a 532-nm Q-switched laser with pulse duration of 15 ns. Each of the evoked phosphorescence decays was analyzed to obtain a sequence of Po2 values that constituted the ODC. Following flow arrest and tissue compression, the interstitial Po2 decreased rapidly and the initial slope of the ODC was used to calculate the V̇o2. Special analysis of instrumental factors affecting the ODC was performed, and the resulting model was used for evaluation of V̇o2. The calculation was based on the observation of only a small amount of residual blood in the tissue after compression. The contribution of oxygen photoconsumption by PQM and oxygen inflow from external sources was evaluated in specially designed tests. The average oxygen consumption of the rat spinotrapezius muscle was V̇o2 = 123.4 ± 13.4 (SE) nl O2/cm3·s (N = 38, within 6 muscles) at a baseline interstitial Po2 of 50.8 ± 2.9 mmHg. This technique has opened the opportunity for monitoring respiration rates in microscopic volumes of functioning skeletal muscle. PMID:20971766

Interstitial water studies on small core samples, Deep Sea Drilling Project, Leg 5

USGS Publications Warehouse

Manheim, F. T.; Chan, K.M.; Sayles, F.L.

1970-01-01

Leg 5 samples fall into two categories with respect to interstitial water composition: 1) rapidly deposited terrigenous or appreciably terrigenous deposits, such as in Hole 35 (western Escanaba trough, off Cape Mendocino, California); and, 2) slowly deposited pelagic clays and biogenic muds and oozes. Interstitial waters in the former show modest to slight variations in chloride and sodium, but drastic changes in non-conservative ions such as magnesium and sulfate. The pelagic deposits show only relatively minor changes in both conservative and non-conservative pore fluid constituents. As was pointed out in earlier Leg Reports, it is believed that much of the variation in chloride in pore fluids within individual holes is attributable to the manipulation of samples on board ship and in the laboratory. On the other hand, the scatter in sodium is due in part to analytical error (on the order of 2 to 3 per cent, in terms of a standard deviation), and it probably accounts for most of the discrepancies in total anion and cation balance. All constituents reported here, with the exception of bulk water content, were analyzed on water samples which were sealed in plastic tubes aboard ship and were subsequently opened and divided into weighed aliquots in the laboratory. Analytical methods follow the atomic absorption, wet chemical and emission spectrochemical techniques briefly summarized in previous reports, e.g. Manheim et al., 1969, and Chan and Manheim, 1970. The authors acknowledge assistance from W. Sunda, D. Kerr, C. Lawson and H. Richards, and thank D. Spencer, P. Brewer and E. Degens for allowing the use of equipment and laboratory facilities.

In situ Raman study on single- and double-walled carbon nanotubes as a function of lithium insertion.

PubMed

Kim, Yoong Ahm; Kojima, Masahito; Muramatsu, Hiroyuki; Umemoto, Souichiro; Watanabe, Takaaki; Yoshida, Kazuto; Sato, Keigo; Ikeda, Takuya; Hayashi, Takuya; Endo, Morinobu; Terrones, Mauricio; Dresselhaus, Mildred S

2006-05-01

We investigated the electrochemical lithium ion (Li(+)) insertion/desertion behavior on highly pure and bundled single- and double-walled carbon nanotubes (SWNTs and DWNTs) using an in situ Raman technique. In general, two storage sites could host Li(+) in SWNT and DWNT bundles when varying an external potential: a) the outer surface sites, and b) the interstitial spaces within the bundles. The most sensitive changes in the tangential mode (TM) of the Raman spectra upon doping with Li(+) can be divided into two regions. The first region was found from 2.8 to 1.0 V (the coverage of Li(+) on the outer surface of a bundled nanotube) and was characterized by the loss of resonant conditions via partial charge transfer, where the G(+) line of the SWNT and the TM of the outer tube of DWNTs experienced a highly depressed intensity, but remained almost constant in frequency. The appearance of a Breit-Wigner-Fano (BWF) profile provided strong evidence of metallic inner tubes within DWNTs. The second region was observed when the applied potentials ranged from 0.9 to 0 V and was characterized by Li(+) diffusion into the interstitial sites of the bundled nanotube material. This phenomenon invoked a large downshift of the G(-) band in SWNTs, and a small downshift of the TM of the inner tube of DWNTs caused by expansion of the C--C bonds due to the charge transferred to the nanotubes, and the disappearance of the BWF profile through the screening effect of the interstitial Li(+) layers.

Populations of subplate and interstitial neurons in fetal and adult human telencephalon.

PubMed

Judaš, Miloš; Sedmak, Goran; Pletikos, Mihovil; Jovanov-Milošević, Nataša

2010-10-01

In the adult human telencephalon, subcortical (gyral) white matter contains a special population of interstitial neurons considered to be surviving descendants of fetal subplate neurons [Kostovic & Rakic (1980) Cytology and the time of origin of interstitial neurons in the white matter in infant and adult human and monkey telencephalon. J Neurocytol9, 219]. We designate this population of cells as superficial (gyral) interstitial neurons and describe their morphology and distribution in the postnatal and adult human cerebrum. Human fetal subplate neurons cannot be regarded as interstitial, because the subplate zone is an essential part of the fetal cortex, the major site of synaptogenesis and the 'waiting' compartment for growing cortical afferents, and contains both projection neurons and interneurons with distinct input-output connectivity. However, although the subplate zone is a transient fetal structure, many subplate neurons survive postnatally as superficial (gyral) interstitial neurons. The fetal white matter is represented by the intermediate zone and well-defined deep periventricular tracts of growing axons, such as the corpus callosum, anterior commissure, internal and external capsule, and the fountainhead of the corona radiata. These tracts gradually occupy the territory of transient fetal subventricular and ventricular zones.The human fetal white matter also contains distinct populations of deep fetal interstitial neurons, which, by virtue of their location, morphology, molecular phenotypes and advanced level of dendritic maturation, remain distinct from subplate neurons and neurons in adjacent structures (e.g. basal ganglia, basal forebrain). We describe the morphological, histochemical (nicotinamide-adenine dinucleotide phosphate-diaphorase) and immunocytochemical (neuron-specific nuclear protein, microtubule-associated protein-2, calbindin, calretinin, neuropeptide Y) features of both deep fetal interstitial neurons and deep (periventricular) interstitial neurons in the postnatal and adult deep cerebral white matter (i.e. corpus callosum, anterior commissure, internal and external capsule and the corona radiata/centrum semiovale). Although these deep interstitial neurons are poorly developed or absent in the brains of rodents, they represent a prominent feature of the significantly enlarged white matter of human and non-human primate brains. © 2010 The Authors. Journal of Anatomy © 2010 Anatomical Society of Great Britain and Ireland.

Galaxy And Mass Assembly (GAMA): the signatures of galaxy interactions as viewed from small scale galaxy clustering

NASA Astrophysics Data System (ADS)

Gunawardhana, M. L. P.; Norberg, P.; Zehavi, I.; Farrow, D. J.; Loveday, J.; Hopkins, A. M.; Davies, L. J. M.; Wang, L.; Alpaslan, M.; Bland-Hawthorn, J.; Brough, S.; Holwerda, B. W.; Owers, M. S.; Wright, A. H.

2018-06-01

Statistical studies of galaxy-galaxy interactions often utilise net change in physical properties of progenitors as a function of the separation between their nuclei to trace both the strength and the observable timescale of their interaction. In this study, we use two-point auto, cross and mark correlation functions to investigate the extent to which small-scale clustering properties of star forming galaxies can be used to gain physical insight into galaxy-galaxy interactions between galaxies of similar optical brightness and stellar mass. The Hα star formers, drawn from the highly spatially complete Galaxy And Mass Assembly (GAMA) survey, show an increase in clustering on small separations. Moreover, the clustering strength shows a strong dependence on optical brightness and stellar mass, where (1) the clustering amplitude of optically brighter galaxies at a given separation is larger than that of optically fainter systems, (2) the small scale clustering properties (e.g. the strength, the scale at which the signal relative to the fiducial power law plateaus) of star forming galaxies appear to differ as a function of increasing optical brightness of galaxies. According to cross and mark correlation analyses, the former result is largely driven by the increased dust content in optically bright star forming galaxies. The latter could be interpreted as evidence of a correlation between interaction-scale and optical brightness of galaxies, where physical evidence of interactions between optically bright star formers, likely hosted within relatively massive halos, persist over larger separations than those between optically faint star formers.

Theoretical study of the electronic and optical properties of photochromic dithienylethene derivatives connected to small gold clusters.

PubMed

Perrier, Aurélie; Maurel, François; Aubard, Jean

2007-10-04

In the course of developing electronic devices on a molecular scale, dithienylethenes photochromic molecules constitute promising candidates for optoelectronic applications such as memories and switches. There is thus a great interest to understand and control the switching behavior of photochromic compounds deposited on metallic surfaces or nanoparticles. Within the framework of the density functional theory, we studied the effect of small gold clusters (Au3 and Au9) on the electronic structure and absorption spectrum of a model dithienylethene molecule. The molecular orbital interactions between the photochromic molecule and the gold cluster made it possible to rationalize some experimental findings (Dulic, D.; van der Molen, S. J.; Kudernac, T.; Jonkman, H. T.; de Jong, J. J. D.; Bowden, T. N.; van Esch, J.; Feringa, B. L.; van Wees, B. J. Phys. Rev. Lett. 2003, 91, 207402). For the closed-ring isomer, grafting a photochromic molecule on a small gold cluster does not change the characteristics of the electronic transition involved in the ring-opening reaction. On the opposite, the absorption spectrum of the photochromic open-ring isomer is strongly modified by the inclusion of the metallic cluster. In agreement with experimental results, our study thus showed that the cycloreversion reaction which involves the closed-ring isomer should be still possible, whereas the ring-closure reaction which involves the open-ring isomer should be inhibited. Connecting a dithienylethene molecule to a small gold cluster hence provides a qualitative comprehension of the photochromic activities of dithienylethenes connected to a gold surface.

Derivatized gold clusters and antibody-gold cluster conjugates

DOEpatents

Hainfeld, James F.; Furuya, Frederic R.

1994-11-01

Antibody- or antibody fragment-gold cluster conjugates are shown wherein the conjugate size can be as small as 5.0 nm. Methods and reagents are disclosed in which antibodies, Fab' or F(ab').sub.2 fragments thereof are covalently bound to a stable cluster of gold atoms. The gold clusters may contain 6, 8, 9, 11, 13, 55 or 67 gold atoms in their inner core. The clusters may also contain radioactive gold. The antibody-cluster conjugates are useful in electron microscopy applications as well as in clinical applications that include imaging, diagnosis and therapy.

Evaluation of phase II toxicity identification evaluation methods for freshwater whole sediment and interstitial water.

PubMed

Phillips, Bryn M; Anderson, Brian S; Hunt, John W; Clark, Sara L; Voorhees, Jennifer P; Tjeerdema, Ron S; Casteline, Jane; Stewart, Margaret

2009-02-01

Phase I whole sediment toxicity identification evaluation (TIE) methods have been developed to characterize the cause of toxicity as organic chemicals, metals, or ammonia. In Phase II identification treatments, resins added to whole sediment to reduce toxicity caused by metals and organics can be separated and eluted much like solid-phase extraction (SPE) columns are eluted for interstitial water. In this study, formulated reference sediments spiked with toxic concentrations of copper, fluoranthene, and nonylphenol were subjected to whole sediment and interstitial water TIE treatments to evaluate Phase I and II TIE procedures for identifying the cause of toxicity to Hyalella azteca. Phase I TIE treatments consisted of adding adsorbent resins to whole sediment, and using SPE columns to remove spiked chemicals from interstitial water. Phase II treatments consisted of eluting resins and SPE columns and the preparation and testing of eluates for toxicity and chemistry. Whole sediment resins and SPE columns significantly reduced toxicity, and the eluates from all treatments contained toxic concentrations of the spiked chemical except for interstitial water fluoranthene. Toxic unit analysis based on median lethal concentrations (LC50s) allowed for the comparison of chemical concentrations among treatments, and demonstrated that the bioavailability of some chemicals was reduced in some samples and treatments. The concentration of fluoranthene in the resin eluate closely approximated the original interstitial water concentration, but the resin eluate concentrations of copper and nonylphenol were much higher than the original interstitial water concentrations. Phase II whole sediment TIE treatments provided complementary lines of evidence to the interstitial water TIE results.

Performance of small cluster surveys and the clustered LQAS design to estimate local-level vaccination coverage in Mali.

PubMed

Minetti, Andrea; Riera-Montes, Margarita; Nackers, Fabienne; Roederer, Thomas; Koudika, Marie Hortense; Sekkenes, Johanne; Taconet, Aurore; Fermon, Florence; Touré, Albouhary; Grais, Rebecca F; Checchi, Francesco

2012-10-12

Estimation of vaccination coverage at the local level is essential to identify communities that may require additional support. Cluster surveys can be used in resource-poor settings, when population figures are inaccurate. To be feasible, cluster samples need to be small, without losing robustness of results. The clustered LQAS (CLQAS) approach has been proposed as an alternative, as smaller sample sizes are required. We explored (i) the efficiency of cluster surveys of decreasing sample size through bootstrapping analysis and (ii) the performance of CLQAS under three alternative sampling plans to classify local VC, using data from a survey carried out in Mali after mass vaccination against meningococcal meningitis group A. VC estimates provided by a 10 × 15 cluster survey design were reasonably robust. We used them to classify health areas in three categories and guide mop-up activities: i) health areas not requiring supplemental activities; ii) health areas requiring additional vaccination; iii) health areas requiring further evaluation. As sample size decreased (from 10 × 15 to 10 × 3), standard error of VC and ICC estimates were increasingly unstable. Results of CLQAS simulations were not accurate for most health areas, with an overall risk of misclassification greater than 0.25 in one health area out of three. It was greater than 0.50 in one health area out of two under two of the three sampling plans. Small sample cluster surveys (10 × 15) are acceptably robust for classification of VC at local level. We do not recommend the CLQAS method as currently formulated for evaluating vaccination programmes.

Free energy of singular sticky-sphere clusters.

PubMed

Kallus, Yoav; Holmes-Cerfon, Miranda

2017-02-01

Networks of particles connected by springs model many condensed-matter systems, from colloids interacting with a short-range potential and complex fluids near jamming, to self-assembled lattices and various metamaterials. Under small thermal fluctuations the vibrational entropy of a ground state is given by the harmonic approximation if it has no zero-frequency vibrational modes, yet such singular modes are at the epicenter of many interesting behaviors in the systems above. We consider a system of N spherical particles, and directly account for the singularities that arise in the sticky limit where the pairwise interaction is strong and short ranged. Although the contribution to the partition function from singular clusters diverges in the limit, its asymptotic value can be calculated and depends on only two parameters, characterizing the depth and range of the potential. The result holds for systems that are second-order rigid, a geometric characterization that describes all known ground-state (rigid) sticky clusters. To illustrate the applications of our theory we address the question of emergence: how does crystalline order arise in large systems when it is strongly disfavored in small ones? We calculate the partition functions of all known rigid clusters up to N≤21 and show the cluster landscape is dominated by hyperstatic clusters (those with more than 3N-6 contacts); singular and isostatic clusters are far less frequent, despite their extra vibrational and configurational entropies. Since the most hyperstatic clusters are close to fragments of a close-packed lattice, this underlies the emergence of order in sticky-sphere systems, even those as small as N=10.

Free energy of singular sticky-sphere clusters

NASA Astrophysics Data System (ADS)

Kallus, Yoav; Holmes-Cerfon, Miranda

2017-02-01

Networks of particles connected by springs model many condensed-matter systems, from colloids interacting with a short-range potential and complex fluids near jamming, to self-assembled lattices and various metamaterials. Under small thermal fluctuations the vibrational entropy of a ground state is given by the harmonic approximation if it has no zero-frequency vibrational modes, yet such singular modes are at the epicenter of many interesting behaviors in the systems above. We consider a system of N spherical particles, and directly account for the singularities that arise in the sticky limit where the pairwise interaction is strong and short ranged. Although the contribution to the partition function from singular clusters diverges in the limit, its asymptotic value can be calculated and depends on only two parameters, characterizing the depth and range of the potential. The result holds for systems that are second-order rigid, a geometric characterization that describes all known ground-state (rigid) sticky clusters. To illustrate the applications of our theory we address the question of emergence: how does crystalline order arise in large systems when it is strongly disfavored in small ones? We calculate the partition functions of all known rigid clusters up to N ≤21 and show the cluster landscape is dominated by hyperstatic clusters (those with more than 3 N -6 contacts); singular and isostatic clusters are far less frequent, despite their extra vibrational and configurational entropies. Since the most hyperstatic clusters are close to fragments of a close-packed lattice, this underlies the emergence of order in sticky-sphere systems, even those as small as N =10 .

Diabetes-related dysfunction of the small intestine and the colon: focus on motility.

PubMed

Horváth, Viktor József; Putz, Zsuzsanna; Izbéki, Ferenc; Körei, Anna Erzsébet; Gerő, László; Lengyel, Csaba; Kempler, Péter; Várkonyi, Tamás

2015-11-01

In contrast to gastric dysfunction, diabetes-related functional impairments of the small and large intestine have been studied less intensively. The gastrointestinal tract accomplishes several functions, such as mixing and propulsion of luminal content, absorption and secretion of ions, water, and nutrients, defense against pathogens, and elimination of waste products. Diverse functions of the gut are regulated by complex interactions among its functional elements, including gut microbiota. The network-forming tissues, the enteric nervous system) and the interstitial cells of Cajal, are definitely impaired in diabetic patients, and their loss of function is closely related to the symptoms in diabetes, but changes of other elements could also play a role in the development of diabetes mellitus-related motility disorders. The development of our understanding over the recent years of the diabetes-induced dysfunctions in the small and large intestine are reviewed in this article.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Shengtong; Chevrier, Daniel M.; Zhang, Peng

Amorphous intermediate phases are vital precursors in the crystallization of many biogenic minerals. While inherent short-range orders have been found in amorphous calcium carbonates (ACCs) relating to different crystalline forms, it has never been clarified experimentally whether such orders already exist in very small clusters less than 2 nm in size. Here, we studied the stability and structure of 10,12-pentacosadiynoic acid (PCDA) protected ACC clusters with a core size of ca. 1.4 nm consisting of only seven CaCO 3 units. Ligand concentration and structure are shown to be key factors in stabilizing the ACC clusters. More importantly, even in suchmore » small CaCO 3 entities, a proto-calcite short-range order can be identified but with a relatively high degree of disorder that arises from the very small size of the CaCO 3 core. Our findings support the notion of a structural link between prenucleation clusters, amorphous intermediates, and final crystalline polymorphs, which appears central to the understanding of polymorph selection.« less

Characteristics of voxel prediction power in full-brain Granger causality analysis of fMRI data

NASA Astrophysics Data System (ADS)

Garg, Rahul; Cecchi, Guillermo A.; Rao, A. Ravishankar

2011-03-01

Functional neuroimaging research is moving from the study of "activations" to the study of "interactions" among brain regions. Granger causality analysis provides a powerful technique to model spatio-temporal interactions among brain regions. We apply this technique to full-brain fMRI data without aggregating any voxel data into regions of interest (ROIs). We circumvent the problem of dimensionality using sparse regression from machine learning. On a simple finger-tapping experiment we found that (1) a small number of voxels in the brain have very high prediction power, explaining the future time course of other voxels in the brain; (2) these voxels occur in small sized clusters (of size 1-4 voxels) distributed throughout the brain; (3) albeit small, these clusters overlap with most of the clusters identified with the non-temporal General Linear Model (GLM); and (4) the method identifies clusters which, while not determined by the task and not detectable by GLM, still influence brain activity.

Depolarizing Effects of Daikenchuto on Interstitial Cells of Cajal from Mouse Small Intestine

PubMed Central

Kim, Hyungwoo; Kim, Hyun Jung; Yang, Dongki; Jung, Myeong Ho; Kim, Byung Joo

2017-01-01

Background: Daikenchuto (DKT; TJ-100, TU-100), a traditional herbal medicineis used in modern medicine to treat gastrointestinal (GI) functional disorders. Interstitial cells of Cajal (ICCs) are the pacemaker cells of the GI tract and play important roles in the regulation of GI motility. Objective: The objective of this study was to investigate the effects of DKT on the pacemaker potentials (PPs) of cultured ICCs from murine small intestine. Materials and Methods: Enzymatic digestions were used to dissociate ICCs from mouse small intestine tissues. All experiments on ICCs were performed after 12 h of culture. The whole-cell patch-clamp configuration was used to record ICC PPs (current clamp mode). All experiments were performed at 30-32°C. Results: In current-clamp modeDKT depolarized and concentration-dependently decreased the amplitudes of PPs. Y25130 (a 5-HT3 receptor antagonist) or SB269970 (a 5-HT7 receptor antagonist) did not block DKT-induced PP depolarization, but RS39604 (a 5-HT4 receptor antagonist) did. Methoctramine (a muscarinic M2 receptor antagonist) failed to block DKT-induced PP depolarization, but pretreating 4-diphenylacetoxy-N-methylpiperidine methiodide (a muscarinic M3 receptor antagonist) facilitated blockade of DKT-induced PP depolarization. Pretreatment with an external Ca2+-free solution or thapsigargin abolished PPsand under these conditions, DKT did not induce PP depolarization. Furthermore Ginseng radix and Zingiberis rhizomes depolarized PPs, whereas Zanthoxyli fructus fruit (the third component of DKT) hyperpolarized PPs. Conclusion: These results suggest that DKT depolarizes ICC PPs in an internal or external Ca2+-dependent manner by stimulating 5-HT4 and M3 receptors. Furthermore, the authors suspect that the component in DKT largely responsible for depolarization is probably also a component of Ginseng radix and Zingiberis rhizomes. SUMMARY Daikenchuto (DKT) depolarized and concentration-dependently decreased the amplitudes of pacemaker potentials (PPs)Y25130 (a 5-HT3 receptor antagonist) or SB269970 (a 5-HT7 receptor antagonist) did not block DKT-induced PP depolarization, but RS39604 (a 5-HT4 receptor antagonist) didMethoctramine (a muscarinic M2 receptor antagonist) failed to block DKT-induced PP depolarization, but pretreating 4-DAMP (a muscarinic M3 receptor antagonist) facilitated blockade of DKT-induced PP depolarizationGinseng radix and Zingiberis rhizomes depolarized PPswhereas Zanthoxyli fructus fruit (the third component of DKT) hyperpolarized PPs. Abbreviation used: DKT: Daikenchuto, GI: Gastrointestinal, ICCs: Interstitial cells of Cajal, PPs: Pacemaker Potentials. PMID:28216898

Depolarizing Effects of Daikenchuto on Interstitial Cells of Cajal from Mouse Small Intestine.

PubMed

Kim, Hyungwoo; Kim, Hyun Jung; Yang, Dongki; Jung, Myeong Ho; Kim, Byung Joo

2017-01-01

Daikenchuto (DKT; TJ-100, TU-100), a traditional herbal medicineis used in modern medicine to treat gastrointestinal (GI) functional disorders. Interstitial cells of Cajal (ICCs) are the pacemaker cells of the GI tract and play important roles in the regulation of GI motility. The objective of this study was to investigate the effects of DKT on the pacemaker potentials (PPs) of cultured ICCs from murine small intestine. Enzymatic digestions were used to dissociate ICCs from mouse small intestine tissues. All experiments on ICCs were performed after 12 h of culture. The whole-cell patch-clamp configuration was used to record ICC PPs (current clamp mode). All experiments were performed at 30-32°C. In current-clamp modeDKT depolarized and concentration-dependently decreased the amplitudes of PPs. Y25130 (a 5-HT 3 receptor antagonist) or SB269970 (a 5-HT 7 receptor antagonist) did not block DKT-induced PP depolarization, but RS39604 (a 5-HT 4 receptor antagonist) did. Methoctramine (a muscarinic M 2 receptor antagonist) failed to block DKT-induced PP depolarization, but pretreating 4-diphenylacetoxy-N-methylpiperidine methiodide (a muscarinic M 3 receptor antagonist) facilitated blockade of DKT-induced PP depolarization. Pretreatment with an external Ca 2+ -free solution or thapsigargin abolished PPsand under these conditions, DKT did not induce PP depolarization. Furthermore Ginseng radix and Zingiberis rhizomes depolarized PPs, whereas Zanthoxyli fructus fruit (the third component of DKT) hyperpolarized PPs. These results suggest that DKT depolarizes ICC PPs in an internal or external Ca 2+ -dependent manner by stimulating 5-HT 4 and M 3 receptors. Furthermore, the authors suspect that the component in DKT largely responsible for depolarization is probably also a component of Ginseng radix and Zingiberis rhizomes. Daikenchuto (DKT) depolarized and concentration-dependently decreased the amplitudes of pacemaker potentials (PPs)Y25130 (a 5-HT 3 receptor antagonist) or SB269970 (a 5-HT 7 receptor antagonist) did not block DKT-induced PP depolarization, but RS39604 (a 5-HT 4 receptor antagonist) didMethoctramine (a muscarinic M 2 receptor antagonist) failed to block DKT-induced PP depolarization, but pretreating 4-DAMP (a muscarinic M 3 receptor antagonist) facilitated blockade of DKT-induced PP depolarizationGinseng radix and Zingiberis rhizomes depolarized PPswhereas Zanthoxyli fructus fruit (the third component of DKT) hyperpolarized PPs. Abbreviation used: DKT: Daikenchuto, GI: Gastrointestinal, ICCs: Interstitial cells of Cajal, PPs: Pacemaker Potentials.

VizieR Online Data Catalog: Shape parameters for 154 Galactic open clusters (Zhai+, 2017)

NASA Astrophysics Data System (ADS)

Zhai, M.; Abt, H.; Zhao, G.; Li, C.

2017-06-01

The data used are from database WEBDA (http://www.univie.ac.at/webda/). We have found 946 open clusters with equatorial coordinates for each cluster member. Since cluster members are easily contaminated by field stars, we have only adopted stars with membership probabilities higher than 70% as cluster members. It is rarely possible to determine a cluster's shape with a small number of members, so we have only considered relatively richer clusters, which host more than 20 of the most probable member stars. After these selections, there are 154 clusters left. (1 data file).

Coxiella burnetii, a hidden pathogen in interstitial lung disease?

PubMed

Melenotte, Cléa; Izaaryene, Jalal-Jean; Gomez, Carine; Delord, Marion; Prudent, Elsa; Lepidi, Hubert; Mediannikov, Oleg; Lacoste, Marion; Djossou, Felix; Mania, Alexandre; Bernard, Noelle; Huchot, Eric; Mège, Jean-Louis; Brégeon, Fabienne; Raoult, Didier

2018-04-06

We report 7 patients with interstitial lung disease (ILD) on CT-scan reviewing. C. burnetii was diagnosed in situ in one lung biopsy performed. All patients had advanced interstitial lung fibrosis and persistent C. burnetii infection. Q fever may be a cofactor of ILD, especially in endemic areas.

[Modern Views on Children's Interstitial Lung Disease].

PubMed

Boĭtsova, E V; Beliashova, M A; Ovsiannikov, D Iu

2015-01-01

Interstitial lung diseases (ILD, diffuse lung diseases) are a heterogeneous group of diseases in which a pathological process primarily involved alveoli and perialveolar interstitium, resulting in impaired gas exchange, restrictive changes of lung ventilation function and diffuse interstitial changes detectable by X-ray. Children's interstitial lung diseases is an topical problem ofpediatricpulmonoogy. The article presents current information about classification, epidemiology, clinical presentation, diagnostics, treatment and prognosis of these rare diseases. The article describes the differences in the structure, pathogenesis, detection of various histological changes in children's ILD compared with adult patients with ILD. Authors cite an instance of registers pediatric patients with ILD. The clinical semiotics of ILD, the possible results of objective research, the frequency of symptoms, the features of medical history, the changes detected on chest X-rays, CT semiotics described in detail. Particular attention was paid to interstitial lung diseases, occurring mainly in newborns and children during the first two years of life, such as congenital deficiencies of surfactant proteins, neuroendocrine cell hyperplasia of infancy, pulmonary interstitial glycogenosis. The diagnostic program for children's ILD, therapy options are presented in this article.

Studies of O18 impurity trapping at interstitial dislocation loops in ion implanted Fe (1 1 0) by ion channeling and ab initio calculations

NASA Astrophysics Data System (ADS)

Mathayan, Vairavel; Kothalamuthu, Saravanan; Gnanasekaran, Jaiganesh; Balakrishnan, Sundaravel; Panigrahi, Binaykumar

2018-01-01

The O18 and self ions are implanted at same depth in Fe (1 1 0) crystal and annealed to study the oxygen trapping under excess self interstitial defects. Rutherford backscattering spectrometry, nuclear reaction analysis and channeling measurements have been performed to determine the lattice site position of O18. The presence of dislocation loops is confirmed by energy-dependent dechanneling parameter measurements. From the tilt angular scans of Fe and O18 signals along 〈1 0 0〉, 〈1 1 0〉 axes, O18 is found to be displaced 0.2 Å from tetrahedral towards octahedral interstitial site in O18. Similar lattice site location of oxygen with the displacement of 0.37 Å is predicted by density functional theory calculations for the interaction of oxygen with 〈1 0 0〉 interstitial dislocation loop structure. Our results provide strong evidence on oxygen trapping at interstitial dislocation loops in the presence of excess interstitial defects in iron.

Feasibility of interstitial diffuse optical tomography using cylindrical diffusing fiber for prostate PDT

PubMed Central

Liang, Xing; Wang, Ken Kang-Hsin; Zhu, Timothy C.

2013-01-01

Interstitial diffuse optical tomography (DOT) has been used to characterize spatial distribution of optical properties for prostate photodynamic therapy (PDT) dosimetry. We have developed an interstitial DOT method using cylindrical diffuse fibers (CDFs) as light sources, so that the same light sources can be used for both DOT measurement and PDT treatment. In this novel interstitial CDF-DOT method, absolute light fluence per source strength (in unit of 1/cm2) is used to separate absorption and scattering coefficients. A mathematical phantom and a solid prostate phantom including anomalies with known optical properties were used, respectively, to test the feasibility of reconstructing optical properties using interstitial CDF-DOT. Three dimension spatial distributions of the optical properties were reconstructed for both scenarios. Our studies show that absorption coefficient can be reliably extrapolated while there are some cross talks between absorption and scattering properties. Even with the suboptimal reduced scattering coefficients, the reconstructed light fluence rate agreed with the measured values to within ±10%, thus the proposed CDF-DOT allows greatly improved light dosimetry calculation for interstitial PDT. PMID:23629149

An observational and thermodynamic investigation of carbonate partial melting

NASA Astrophysics Data System (ADS)

Floess, David; Baumgartner, Lukas P.; Vonlanthen, Pierre

2015-01-01

Melting experiments available in the literature show that carbonates and pelites melt at similar conditions in the crust. While partial melting of pelitic rocks is common and well-documented, reports of partial melting in carbonates are rare and ambiguous, mainly because of intensive recrystallization and the resulting lack of criteria for unequivocal identification of melting. Here we present microstructural, textural, and geochemical evidence for partial melting of calcareous dolomite marbles in the contact aureole of the Tertiary Adamello Batholith. Petrographic observations and X-ray micro-computed tomography (X-ray μCT) show that calcite crystallized either in cm- to dm-scale melt pockets, or as an interstitial phase forming an interconnected network between dolomite grains. Calcite-dolomite thermometry yields a temperature of at least 670 °C, which is well above the minimum melting temperature of ∼600 °C reported for the CaO-MgO-CO2-H2O system. Rare-earth element (REE) partition coefficients (KDcc/do) range between 9-35 for adjacent calcite-dolomite pairs. These KD values are 3-10 times higher than equilibrium values between dolomite and calcite reported in the literature. They suggest partitioning of incompatible elements into a melt phase. The δ18O and δ13C isotopic values of calcite and dolomite support this interpretation. Crystallographic orientations measured by electron backscattered diffraction (EBSD) show a clustering of c-axes for dolomite and interstitial calcite normal to the foliation plane, a typical feature for compressional deformation, whereas calcite crystallized in pockets shows a strong clustering of c-axes parallel to the pocket walls, suggesting that it crystallized after deformation had stopped. All this together suggests the formation of partial melts in these carbonates. A Schreinemaker analysis of the experimental data for a CO2-H2O fluid-saturated system indeed predicts formation of calcite-rich melt between 650-880 °C, in agreement with our observations of partial melting. The presence of partial melts in crustal carbonates has important physical and chemical implications, including a drastic drop in rock viscosity and significant change in the dynamics and distribution of fluids within both the contact aureole and the intrusive body.

Vacancy clustering and acceptor activation in nitrogen-implanted ZnO

NASA Astrophysics Data System (ADS)

Børseth, Thomas Moe; Tuomisto, Filip; Christensen, Jens S.; Monakhov, Edouard V.; Svensson, Bengt G.; Kuznetsov, Andrej Yu.

2008-01-01

The role of vacancy clustering and acceptor activation on resistivity evolution in N ion-implanted n -type hydrothermally grown bulk ZnO has been investigated by positron annihilation spectroscopy, resistivity measurements, and chemical profiling. Room temperature 220keV N implantation using doses in the low 1015cm-2 range induces small and big vacancy clusters containing at least 2 and 3-4 Zn vacancies, respectively. The small clusters are present already in as-implanted samples and remain stable up to 1000°C with no significant effect on the resistivity evolution. In contrast, formation of the big clusters at 600°C is associated with a significant increase in the free electron concentration attributed to gettering of amphoteric Li impurities by these clusters. Further annealing at 800°C results in a dramatic decrease in the free electron concentration correlated with activation of 1016-1017cm-3 acceptors likely to be N and/or Li related. The samples remain n type, however, and further annealing at 1000°C results in passivation of the acceptor states while the big clusters dissociate.

Symmetries and stability of chimera states in small, globally-coupled networks

NASA Astrophysics Data System (ADS)

Hart, Joseph D.; Bansal, Kanika; Murphy, Thomas E.; Roy, Rajarshi

It has recently been demonstrated that symmetries in a network's topology can help predict the patterns of synchronized clusters that can emerge in a network of coupled oscillators. This and related discoveries have led to increased interest in both network symmetries and cluster synchronization. In parallel with these discoveries, interest in chimera states-dynamical patterns in which a network separates into coherent and incoherent portions-has grown, and chimeras have now been observed in a variety of experimental systems. We present an opto-electronic experiment in which both chimera states and synchronized clusters are observed in a small, globally-coupled network. We show that the symmetries and sub-symmetries of the network permit the formation of the chimera and cluster states. A recently developed group theoretical approach enables us to predict the stability of the observed chimera and cluster states, and highlights the close relationship between chimera and cluster states as belonging to the broader phenomenon of partial synchronization.

Size dependent fragmentation of argon clusters in the soft x-ray ionization regime

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gisselbrecht, Mathieu; Lindgren, Andreas; Burmeister, Florian

Photofragmentation of argon clusters of average size ranging from 10 up to 1000 atoms is studied using soft x-ray radiation below the 2p threshold and multicoincidence mass spectroscopy technique. For small clusters (=10), ionization induces fast fragmentation with neutral emission imparting a large amount of energy. While the primary dissociation takes place on a picosecond time scale, the fragments undergo slow degradation in the spectrometer on a microsecond time scale. For larger clusters ({>=}100) we believe that we observe the fragmentation pattern of multiply charged species on a time-scale which lasts a few hundred nanoseconds. The reason for these slowermore » processes is the large number of neutral atoms which act as an efficient cooling bath where the excess energy ('heat') dissipates among all degrees of freedom. Further degradation of the photoionic cluster in spectrometer then takes place on the microsecond time scale, similar to small clusters.« less

Polymorphism in magic-sized Au144(SR)60 clusters

NASA Astrophysics Data System (ADS)

Jensen, Kirsten M. Ø.; Juhas, Pavol; Tofanelli, Marcus A.; Heinecke, Christine L.; Vaughan, Gavin; Ackerson, Christopher J.; Billinge, Simon J. L.

2016-06-01

Ultra-small, magic-sized metal nanoclusters represent an important new class of materials with properties between molecules and particles. However, their small size challenges the conventional methods for structure characterization. Here we present the structure of ultra-stable Au144(SR)60 magic-sized nanoclusters obtained from atomic pair distribution function analysis of X-ray powder diffraction data. The study reveals structural polymorphism in these archetypal nanoclusters. In addition to confirming the theoretically predicted icosahedral-cored cluster, we also find samples with a truncated decahedral core structure, with some samples exhibiting a coexistence of both cluster structures. Although the clusters are monodisperse in size, structural diversity is apparent. The discovery of polymorphism may open up a new dimension in nanoscale engineering.

Cooperative network clustering and task allocation for heterogeneous small satellite network

NASA Astrophysics Data System (ADS)

Qin, Jing

The research of small satellite has emerged as a hot topic in recent years because of its economical prospects and convenience in launching and design. Due to the size and energy constraints of small satellites, forming a small satellite network(SSN) in which all the satellites cooperate with each other to finish tasks is an efficient and effective way to utilize them. In this dissertation, I designed and evaluated a weight based dominating set clustering algorithm, which efficiently organizes the satellites into stable clusters. The traditional clustering algorithms of large monolithic satellite networks, such as formation flying and satellite swarm, are often limited on automatic formation of clusters. Therefore, a novel Distributed Weight based Dominating Set(DWDS) clustering algorithm is designed to address the clustering problems in the stochastically deployed SSNs. Considering the unique features of small satellites, this algorithm is able to form the clusters efficiently and stably. In this algorithm, satellites are separated into different groups according to their spatial characteristics. A minimum dominating set is chosen as the candidate cluster head set based on their weights, which is a weighted combination of residual energy and connection degree. Then the cluster heads admit new neighbors that accept their invitations into the cluster, until the maximum cluster size is reached. Evaluated by the simulation results, in a SSN with 200 to 800 nodes, the algorithm is able to efficiently cluster more than 90% of nodes in 3 seconds. The Deadline Based Resource Balancing (DBRB) task allocation algorithm is designed for efficient task allocations in heterogeneous LEO small satellite networks. In the task allocation process, the dispatcher needs to consider the deadlines of the tasks as well as the residue energy of different resources for best energy utilization. We assume the tasks adopt a Map-Reduce framework, in which a task can consist of multiple subtasks. The DBRB algorithm is deployed on the head node of a cluster. It gathers the status from each cluster member and calculates their Node Importance Factors (NIFs) from the carried resources, residue power and compute capacity. The algorithm calculates the number of concurrent subtasks based on the deadlines, and allocates the subtasks to the nodes according to their NIF values. The simulation results show that when cluster members carry multiple resources, resource are more balanced and rare resources serve longer in DBRB than in the Earliest Deadline First algorithm. We also show that the algorithm performs well in service isolation by serving multiple tasks with different deadlines. Moreover, the average task response time with various cluster size settings is well controlled within deadlines as well. Except non-realtime tasks, small satellites may execute realtime tasks as well. The location-dependent tasks, such as image capturing, data transmission and remote sensing tasks are realtime tasks that are required to be started / finished on specific time. The resource energy balancing algorithm for realtime and non-realtime mixed workload is developed to efficiently schedule the tasks for best system performance. It calculates the residue energy for each resource type and tries to preserve resources and node availability when distributing tasks. Non-realtime tasks can be preempted by realtime tasks to provide better QoS to realtime tasks. I compared the performance of proposed algorithm with a random-priority scheduling algorithm, with only realtime tasks, non-realtime tasks and mixed tasks. It shows the resource energy reservation algorithm outperforms the latter one with both balanced and imbalanced workloads. Although the resource energy balancing task allocation algorithm for mixed workload provides preemption mechanism for realtime tasks, realtime tasks can still fail due to resource exhaustion. For LEO small satellite flies around the earth on stable orbits, the location-dependent realtime tasks can be considered as periodical tasks. Therefore, it is possible to reserve energy for these realtime tasks. The resource energy reservation algorithm preserves energy for the realtime tasks when the execution routine of periodical realtime tasks is known. In order to reserve energy for tasks starting very early in each period that the node does not have enough energy charged, an energy wrapping mechanism is also designed to calculate the residue energy from the previous period. The simulation results show that without energy reservation, realtime task failure rate can reach more than 60% when the workload is highly imbalanced. In contrast, the resource energy reservation produces zero RT task failures and leads to equal or better aggregate system throughput than the non-reservation algorithm. The proposed algorithm also preserves more energy because it avoids task preemption. (Abstract shortened by ProQuest.).

Impacts of nitric oxide and superoxide on renal medullary oxygen transport and urine concentration.

PubMed

Fry, Brendan C; Edwards, Aurélie; Layton, Anita T

2015-05-01

The goal of this study was to investigate the reciprocal interactions among oxygen (O2), nitric oxide (NO), and superoxide (O2 (-)) and their effects on medullary oxygenation and urinary output. To accomplish that goal, we developed a detailed mathematical model of solute transport in the renal medulla of the rat kidney. The model represents the radial organization of the renal tubules and vessels, which centers around the vascular bundles in the outer medulla and around clusters of collecting ducts in the inner medulla. Model simulations yield significant radial gradients in interstitial fluid oxygen tension (Po2) and NO and O2 (-) concentration in the OM and upper IM. In the deep inner medulla, interstitial fluid concentrations become much more homogeneous, as the radial organization of tubules and vessels is not distinguishable. The model further predicts that due to the nonlinear interactions among O2, NO, and O2 (-), the effects of NO and O2 (-) on sodium transport, osmolality, and medullary oxygenation cannot be gleaned by considering each solute's effect in isolation. An additional simulation suggests that a sufficiently large reduction in tubular transport efficiency may be the key contributing factor, more so than oxidative stress alone, to hypertension-induced medullary hypoxia. Moreover, model predictions suggest that urine Po2 could serve as a biomarker for medullary hypoxia and a predictor of the risk for hospital-acquired acute kidney injury. Copyright © 2015 the American Physiological Society.

Impacts of nitric oxide and superoxide on renal medullary oxygen transport and urine concentration

PubMed Central

Edwards, Aurélie; Layton, Anita T.

2015-01-01

The goal of this study was to investigate the reciprocal interactions among oxygen (O2), nitric oxide (NO), and superoxide (O2−) and their effects on medullary oxygenation and urinary output. To accomplish that goal, we developed a detailed mathematical model of solute transport in the renal medulla of the rat kidney. The model represents the radial organization of the renal tubules and vessels, which centers around the vascular bundles in the outer medulla and around clusters of collecting ducts in the inner medulla. Model simulations yield significant radial gradients in interstitial fluid oxygen tension (Po2) and NO and O2− concentration in the OM and upper IM. In the deep inner medulla, interstitial fluid concentrations become much more homogeneous, as the radial organization of tubules and vessels is not distinguishable. The model further predicts that due to the nonlinear interactions among O2, NO, and O2−, the effects of NO and O2− on sodium transport, osmolality, and medullary oxygenation cannot be gleaned by considering each solute's effect in isolation. An additional simulation suggests that a sufficiently large reduction in tubular transport efficiency may be the key contributing factor, more so than oxidative stress alone, to hypertension-induced medullary hypoxia. Moreover, model predictions suggest that urine Po2 could serve as a biomarker for medullary hypoxia and a predictor of the risk for hospital-acquired acute kidney injury. PMID:25651567

A characterization of the coupled evolution of grain fabric and pore space using complex networks: Pore connectivity and optimized flows in the presence of shear bands

NASA Astrophysics Data System (ADS)

Russell, Scott; Walker, David M.; Tordesillas, Antoinette

2016-03-01

A framework for the multiscale characterization of the coupled evolution of the solid grain fabric and its associated pore space in dense granular media is developed. In this framework, a pseudo-dual graph transformation of the grain contact network produces a graph of pores which can be readily interpreted as a pore space network. Survivability, a new metric succinctly summarizing the connectivity of the solid grain and pore space networks, measures material robustness. The size distribution and the connectivity of pores can be characterized quantitatively through various network properties. Assortativity characterizes the pore space with respect to the parity of the number of particles enclosing the pore. Multiscale clusters of odd parity versus even parity contact cycles alternate spatially along the shear band: these represent, respectively, local jamming and unjamming regions that continually switch positions in time throughout the failure regime. Optimal paths, established using network shortest paths in favor of large pores, provide clues on preferential paths for interstitial matter transport. In systems with higher rolling resistance at contacts, less tortuous shortest paths thread through larger pores in shear bands. Notably the structural patterns uncovered in the pore space suggest that more robust models of interstitial pore flow through deforming granular systems require a proper consideration of the evolution of in situ shear band and fracture patterns - not just globally, but also inside these localized failure zones.

Statistical study of defects caused by primary knock-on atoms in fcc Cu and bcc W using molecular dynamics

NASA Astrophysics Data System (ADS)

Warrier, M.; Bhardwaj, U.; Hemani, H.; Schneider, R.; Mutzke, A.; Valsakumar, M. C.

2015-12-01

We report on molecular Dynamics (MD) simulations carried out in fcc Cu and bcc W using the Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) code to study (i) the statistical variations in the number of interstitials and vacancies produced by energetic primary knock-on atoms (PKA) (0.1-5 keV) directed in random directions and (ii) the in-cascade cluster size distributions. It is seen that around 60-80 random directions have to be explored for the average number of displaced atoms to become steady in the case of fcc Cu, whereas for bcc W around 50-60 random directions need to be explored. The number of Frenkel pairs produced in the MD simulations are compared with that from the Binary Collision Approximation Monte Carlo (BCA-MC) code SDTRIM-SP and the results from the NRT model. It is seen that a proper choice of the damage energy, i.e. the energy required to create a stable interstitial, is essential for the BCA-MC results to match the MD results. On the computational front it is seen that in-situ processing saves the need to input/output (I/O) atomic position data of several tera-bytes when exploring a large number of random directions and there is no difference in run-time because the extra run-time in processing data is offset by the time saved in I/O.

The Cluster Environment of Two High-mass Protostars

NASA Astrophysics Data System (ADS)

Montes, Virginie; Hofner, Peter

2017-06-01

Characterizing the environment and stellar population in which high-mass stars form is an important step to decide between the main massive star formation theories. In the monolithic collapse model, the mass of the core will determine the final stellar mass (e.g., McKee & Tan 2003). In contrast, in the competitive accretion model (e.g., Bonnell & Bate 2006), the mass of the high-mass star is related to the properties of the cluster. As dynamical processes substantially affect the appearance of a cluster, we study early stages of high-mass star formation. These regions often show extended emission from hot dust at infrared wavelengths, which can cause difficulties to define the cluster. We use a multi-wavelength technique to study nearby high-mass star clusters, based on X-ray observations with the Chandra X-Ray Telescope, in conjunction with infrared data and VLA data. The technique relies on the fact that YSOs are particularly bright in X-ray and that contamination is relatively small. X-ray observations allow us to determine the cluster size. The cluster membership and YSOs classification is established using infrared identification of the X-ray sources, and color-color and color-magnitude diagrams.In this talk, I will present our findings on the cluster study of two high-mass star forming regions: IRAS 20126+4104 and IRAS 16562-3959. While most massive stars appear to be formed in rich a cluster environment, those two sources are candidates for the formation of massive stars in a relatively poor cluster. In contrast to what was found in previous studies (Qiu et al. 2008), the dominant B0-type protostar in IRAS 20126+4104 is associated with a small cluster of low-mass stars. I will also show our current work on IRAS 16562-3959, which contains one of the most luminous O-type protostars in the Galaxy. In the vicinity of this particularly interesting region there is a multitude of small clusters, for which I will present how their stellar population differ from the high-mass star-forming cluster IRAS 16562-3959.

Species collapse via hybridization in Darwin's tree finches.

PubMed

Kleindorfer, Sonia; O'Connor, Jody A; Dudaniec, Rachael Y; Myers, Steven A; Robertson, Jeremy; Sulloway, Frank J

2014-03-01

Species hybridization can lead to fitness costs, species collapse, and novel evolutionary trajectories in changing environments. Hybridization is predicted to be more common when environmental conditions change rapidly. Here, we test patterns of hybridization in three sympatric tree finch species (small tree finch Camarhynchus parvulus, medium tree finch Camarhynchus pauper, and large tree finch: Camarhynchus psittacula) that are currently recognized on Floreana Island, Galápagos Archipelago. Genetic analysis of microsatellite data from contemporary samples showed two genetic populations and one hybrid cluster in both 2005 and 2010; hybrid individuals were derived from genetic population 1 (small morph) and genetic population 2 (large morph). Females of the large and rare species were more likely to pair with males of the small common species. Finch populations differed in morphology in 1852-1906 compared with 2005/2010. An unsupervised clustering method showed (a) support for three morphological clusters in the historical tree finch sample (1852-1906), which is consistent with current species recognition; (b) support for two or three morphological clusters in 2005 with some (19%) hybridization; and (c) support for just two morphological clusters in 2010 with frequent (41%) hybridization. We discuss these findings in relation to species demarcations of Camarhynchus tree finches on Floreana Island.

First principles investigations of small bimetallic PdGa clusters as catalysts for hydrogen dissociation

NASA Astrophysics Data System (ADS)

Kaul, Indu; Ghosh, Prasenjit

2017-04-01

Using first principles density functional theory based calculations, we have studied hydrogen dissociation on sub nanometer bimetallic clusters formed from d-block (Pd) and p-block (Ga) elements in gas phase to explore the feasibility of using them as cheap catalysts for hydrogen dissociation. Our calculations show that the dimers, trimers and tetramers of these clusters are thermodynamically more stable than the pure ones for all Ga concentrations. For a given cluster size, we find that the clusters containing equal amount of Pd and Ga are the most stable ones. In contrast to bulk PdGa, the contribution of Pd-d states to the highest occupied molecular orbitals of the bimetallic clusters are either very small or absent. Study of adsorption of hydrogen molecule on these clusters show that hydrogen binds in an activated form only on the Pd rich clusters. From the calculations of hydrogen dissociation barriers on tetramers of pure Pd, 25% Ga (Pd3Ga) and 50% Ga (Pd2Ga2) we find that Pd3Ga is the most efficient catalyst for hydrogen dissociation with barriers even lower than that on the PdGa surfaces.

Observation of small cluster formation in concentrated monoclonal antibody solutions and its implications to solution viscosity.

PubMed

Yearley, Eric J; Godfrin, Paul D; Perevozchikova, Tatiana; Zhang, Hailiang; Falus, Peter; Porcar, Lionel; Nagao, Michihiro; Curtis, Joseph E; Gawande, Pradad; Taing, Rosalynn; Zarraga, Isidro E; Wagner, Norman J; Liu, Yun

2014-04-15

Monoclonal antibodies (mAbs) are a major class of biopharmaceuticals. It is hypothesized that some concentrated mAb solutions exhibit formation of a solution phase consisting of reversibly self-associated aggregates (or reversible clusters), which is speculated to be responsible for their distinct solution properties. Here, we report direct observation of reversible clusters in concentrated solutions of mAbs using neutron spin echo. Specifically, a stable mAb solution is studied across a transition from dispersed monomers in dilute solution to clustered states at more concentrated conditions, where clusters of a preferred size are observed. Once mAb clusters have formed, their size, in contrast to that observed in typical globular protein solutions, is observed to remain nearly constant over a wide range of concentrations. Our results not only conclusively establish a clear relationship between the undesirable high viscosity of some mAb solutions and the formation of reversible clusters with extended open structures, but also directly observe self-assembled mAb protein clusters of preferred small finite size similar to that in micelle formation that dominate the properties of concentrated mAb solutions. Copyright © 2014 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Temporal and spatial variations in kinetics of alkaline phosphatase in sediments of a shallow Chinese eutrophic lake (Lake Donghu).

PubMed

Yiyong, Zhou; Jianqiu, Li; Min, Zhang

2002-04-01

Monthly sediment and interstitial water samples were collected in a shallow Chinese freshwater lake (Lake Donghu) from three areas to determine if alkaline phosphatase activity (APA) plays an important role, in phosphorus cycling in sediment. The seasonal variability in the kinetics of APA and other relevant parameters were investigated from 1995-1996. The phosphatase hydrolyzable phosphorus (PHP) fluctuated seasonally in interstitial water, peaking in the spring. A synchronous pattern was observed in chlorophyll a contents in surface water in general. The orthophosphate (o-P) concentrations in the interstitial water increased during the spring. An expected negative relationship between PHP and Vmax of APA is not evident in interstitial water. The most striking feature of the two variables is their co-occurring, which can be explained in terms of an induction mechanism. It is argued that phosphatase activity mainly contributes to the driving force of o-P regeneration from PHP in interstitial water, supporting the development of phytoplankton biomass in spring. The Vmax values in sediment increased during the summer, in conjunction with lower Km values in interstitial water that suggest a higher affinity for the substrate. The accumulation of organic matter in the sediment could be traced back to the breakdown of the algal spring bloom, which may stimulate APA with higher kinetic efficiency, by a combination of the higher Vmax in sediments plus lower Km values in interstitial water, in summer. In summary, a focus on phosphatase and its substrate in annual scale may provide a useful framework for the development of novel P cycling, possible explanations for the absence of a clear relationship between PHP and APA were PHP released from the sediment which induced APA, and the presence of kinetically higher APA both in sediment and interstitial water which permitted summer mineralization of organic matter derived from the spring bloom to occur. The study highlighted the need for distinguishing functionally distinct extracellular enzymes between the sediment and interstitial water of lakes.

Native interstitial defects in ZnGeN2

NASA Astrophysics Data System (ADS)

Skachkov, Dmitry; Lambrecht, Walter R. L.

2017-10-01

A density functional study is presented of the interstitial Zni, Gei, and Ni in ZnGeN2. Corrections to the band gap are included by means of the LDA+U method. The Zn and Ge interstitials are both found to strongly prefer the larger octahedral site compared to the two types of tetrahedral sites. The Zn interstitial is found to be a shallow double donor, but it has higher energy than previously studied antisite defects. It has a resonance in the conduction band that is Zn-s like. The Ge interstitial is an even higher energy of formation defect and also behaves as a shallow double donor, but it also has a deep level in the gap corresponding to a Ge-s orbital character while the Ge-p forms a resonance in the conduction band. The nitrogen interstitial forms a split-interstitial configuration, as also occurs in GaN. Its electronic levels can be related to that of a N2 molecule. The defect levels in the gap correspond to the πg-like lowest unoccupied molecular orbital of the molecule, which here becomes filled with three electrons in the defect's neutral charge state. They are found to prefer a high-spin configuration in the q =+1 state. The corresponding transition levels are obtained and show that this is an amphoteric trap level occurring in +2 , +1 , 0, and -1 charge states. The two possible sites for this split interstitial, on top of Zn or on top of Ge, differ slightly in N2 bond length. While the Ni defects have the lowest formation energy among the interstitials, it is still higher than that of the antisites. Hence they are not expected to occur in sufficient concentration to affect the intrinsic Fermi level position. In particular, they do not contribute to the unintentional n -type background doping.

Impurity and defect interactions during laser thermal annealing in Ge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Milazzo, R., E-mail: ruggero.milazzo@unipd.it; De Salvador, D.; Carnera, A.

2016-01-28

The microscopic mechanisms involving dopants, contaminants, and defects in Ge during pulsed melting laser thermal annealing (LTA) are investigated in detail. Samples both un-implanted and implanted with As or B are processed by LTA as well as characterized in terms of chemical (1D and 3D), electrical, and strain profiling. The clustering of As is directly measured by 3D chemical profiling and correlated with its partial electrical activation along with a reduction of the lattice strain induced by As atoms. A semi-quantitative microscopic model involving the interaction with mobile As-vacancy (AsV) complexes is proposed to describe the clustering mechanism. Boron ismore » shown to follow different clustering behavior that changes with depth and marked by completely different strain levels. Oxygen penetrates from the surface into all the samples as a result of LTA and, only in un-implanted Ge, it occupies an interstitial position inducing also positive strain in the lattice. On the contrary, data suggest that the presence of As or B forces O to assume different configurations with negligible strain, through O-V or O-B interactions for the two dopant species, respectively. These data suggest that LTA does not inject a significant amount of vacancies in Ge, at variance with Si, unless As atoms or possibly other n-type dopants are present. These results have to be carefully considered for modeling the LTA process in Ge and its implementation in technology.« less

Lattice strain in irradiated materials unveils a prevalent defect evolution mechanism

NASA Astrophysics Data System (ADS)

Debelle, Aurélien; Crocombette, Jean-Paul; Boulle, Alexandre; Chartier, Alain; Jourdan, Thomas; Pellegrino, Stéphanie; Bachiller-Perea, Diana; Carpentier, Denise; Channagiri, Jayanth; Nguyen, Tien-Hien; Garrido, Frédérico; Thomé, Lionel

2018-01-01

Modification of materials using ion beams has become a widespread route to improve or design materials for advanced applications, from ion doping for microelectronic devices to emulation of nuclear reactor environments. Yet, despite decades of studies, major issues regarding ion/solid interactions are not solved, one of them being the lattice-strain development process in irradiated crystals. In this work, we address this question using a consistent approach that combines x-ray diffraction (XRD) measurements with both molecular dynamics (MD) and rate equation cluster dynamics (RECD) simulations. We investigate four distinct materials that differ notably in terms of crystalline structure and nature of the atomic bonding. We demonstrate that these materials exhibit a common behavior with respect to the strain development process. In fact, a strain build-up followed by a strain relaxation is observed in the four investigated cases. The strain variation is unambiguously ascribed to a change in the defect configuration, as revealed by MD simulations. Strain development is due to the clustering of interstitial defects into dislocation loops, while the strain release is associated with the disappearance of these loops through their integration into a network of dislocation lines. RECD calculations of strain depth profiles, which are in agreement with experimental data, indicate that the driving force for the change in the defect nature is the defect clustering process. This study paves the way for quantitative predictions of the microstructure changes in irradiated materials.

Interstitial-phase precipitation in iron-base alloys: a comparative study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pelton, A.R.

1982-06-01

Recent developments have elucidated the atomistic mechanisms of precipitation of interstitial elements in simple alloy systems. However, in the more technologically important iron base alloys, interstitial phase precipitation is generally not well understood. The present experimental study was therefore designed to test the applicability of these concepts to more complex ferrous alloys. Hence, a comparative study was made of interstitial phase precipitation in ferritic Fe-Si-C and in austenitic phosphorus-containing Fe-Cr-Ni steels. These systems were subjected to a variety of quench-age thermal treatments, and the microstructural development was subsequently characterized by transmission electron microscopy.

Quantum chemical study of small AlnBm clusters: Structure and physical properties

NASA Astrophysics Data System (ADS)

Loukhovitski, Boris I.; Sharipov, Alexander S.; Starik, Alexander M.

2017-08-01

The structure and physical properties, including rotational constants, characteristic vibrational temperatures, collision diameter, dipole moment, static polarizability, the energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), and formation enthalpy of the different isomeric forms of AlnBm clusters with n + m ⩽ 7 are studied using density functional theory. The search of the structure of isomers has been carried employing multistep hierarchical algorithm. Temperature dependencies of thermodynamic functions, such as enthalpy, entropy, and specific heat capacity, have been determined both for the individual isomers and for the ensembles with equilibrium and frozen compositions for the each class of clusters taking into account the anharmonicity of cluster vibrations and the contribution of their excited electronic states. The prospects of the application of small AlnBm clusters as the components of energetic materials are also considered.

Near-Infrared Spectroscopy of Small Protonated Water Clusters

NASA Astrophysics Data System (ADS)

Wagner, J. Philipp; McDonald, David C., II; McCoy, Anne B.; Duncan, Michael A.

2017-06-01

Small protonated water clusters and their argon tagged analogues of the general formula H^{+}(H_{2}O)_{n}Ar_{m} have been generated in a pulsed electric discharge source. Clusters containing n=1-8 water molecules were mass-selected and their absorptions in the near-infrared were probed with a tunable Nd/colonYAG pumped OPA/OPA laser system in the region from 4850-7350 cm^{-1}. A doublet corresponding to overtones of the free O-H stretches of the external waters was observed around 7200 cm^{-1} that was continuously decreasing in intensity with increasing cluster size. Broad, mostly featureless absorptions were found around 5300 cm^{-1} associated with stretch/bend combinations and with the hydrogen bonded waters in the core of the clusters. Vibrational assignments were substantiated by comparison to anharmonic frequency computations via second-order vibrational perturbation theory (VPT2) at the MP2/aug-cc-pVTZ level of theory.

Elucidation of Proton-Assisted Fluxionality in Transition-Metal Oxide Clusters

NASA Astrophysics Data System (ADS)

Ramabhadran, Raghunath O.; Mayhall, Nicholas J.; Becher, Edwin L. Becher, Iii; Chowdhury, Arefin; Raghavachari, Krishnan

2012-06-01

The phenomenon of fluxionality in the reactions of transition-metal oxide clusters provides many opportunities in various industrial and catalytic processes. We present an electronic structure investigation of the fluxionality pathways when anionic W3O6- and Mo3O6- clusters react with three small molecules - water, ammonia and hydrogen sulfide. The presentation features a detailed understanding of (a) how the fluxionality pathway occurs and (b) the various factors that affect the fluxionality pathway - such as the metal, different spin-states and the nature of the non-metal in the reacting small molecule.

A Case Control Study Reveals that Polyomaviruria Is Significantly Associated with Interstitial Cystitis and Vesical Ulceration

PubMed Central

Winter, Benjamin J.; O'Connell, Helen E.; Bowden, Scott; Carey, Marcus; Eisen, Damon P.

2015-01-01

Objectives To investigate whether polyomaviruses contribute to interstitial cystitis pathogenesis. Subjects and Methods A prospective study was performed with 50 interstitial cystitis cases compared with 50 age-matched, disease-free controls for the frequency of polyomaviruria. Associations between polyomaviruria and disease characteristics were analysed in cases. Polyomavirus in urine and bladder tissue was detected with species (JC virus vs. BK virus) specific, real-time PCR. Results Case patients were reflective of interstitial cystitis epidemiology with age range from 26–88 years (median 58) and female predominance (41/50 F). There was a significant increase in the frequency of polyomavirus shedding between cases and controls (p<0.02). Polyomavirus shedding, in particular BK viruria, was associated with vesical ulceration, a marker of disease severity, among interstitial cystitis cases after adjustment for age and sex (OR 6.8, 95% CI 1.89–24.4). There was a significant association among cases between the presence of BK viruria and response to intravesical Clorpactin therapy (OR 4.50, 95% CI 1.17–17.4). Conclusion The presence of polyomaviruria was found to be associated with the ulcerative form of interstitial cystitis. Clorpactin, which has anti-DNA virus activity, was more likely to improve symptoms in the presence of BK viruria. These data from this pilot study suggest associations between polyomaviruria and interstitial cystitis warranting further investigation. PMID:26325074

Primary radiation damage of Zr-0.5%Nb binary alloy: atomistic simulation by molecular dynamics method

NASA Astrophysics Data System (ADS)

Tikhonchev, M.; Svetukhin, V.; Kapustin, P.

2017-09-01

Ab initio calculations predict high positive binding energy (˜1 eV) between niobium atoms and self-interstitial configurations in hcp zirconium. It allows the expectation of increased niobium fraction in self-interstitials formed under neutron irradiation in atomic displacement cascades. In this paper, we report the results of molecular dynamics simulation of atomic displacement cascades in Zr-0.5%Nb binary alloy and pure Zr at the temperature of 300 K. Two sets of n-body interatomic potentials have been used for the Zr-Nb system. We consider a cascade energy range of 2-20 keV. Calculations show close estimations of the average number of produced Frenkel pairs in the alloy and pure Zr. A high fraction of Nb is observed in the self-interstitial configurations. Nb is mainly detected in single self-interstitial configurations, where its fraction reaches tens of percent, i.e. more than its tenfold concentration in the matrix. The basic mechanism of this phenomenon is the trapping of mobile self-interstitial configurations by niobium. The diffusion of pure zirconium and mixed zirconium-niobium self-interstitial configurations in the zirconium matrix at 300 K has been simulated. We observe a strong dependence of the estimated diffusion coefficients and fractions of Nb in self-interstitials produced in displacement cascades on the potential.

A systematic review of validated methods for identifying pulmonary fibrosis and interstitial lung disease using administrative and claims data.

PubMed

Jones, Natalie; Schneider, Gary; Kachroo, Sumesh; Rotella, Philip; Avetisyan, Ruzan; Reynolds, Matthew W

2012-01-01

The Food and Drug Administration's Mini-Sentinel pilot program initially aimed to conduct active surveillance to refine safety signals that emerge for marketed medical products. A key facet of this surveillance is to develop and understand the validity of algorithms for identifying health outcomes of interest (HOIs) from administrative and claims data. This paper summarizes the process and findings of the algorithm review of pulmonary fibrosis and interstitial lung disease. PubMed and Iowa Drug Information Service Web searches were conducted to identify citations applicable to the pulmonary fibrosis/interstitial lung disease HOI. Level 1 abstract reviews and Level 2 full-text reviews were conducted to find articles using administrative and claims data to identify pulmonary fibrosis and interstitial lung disease, including validation estimates of the coding algorithms. Our search revealed a deficiency of literature focusing on pulmonary fibrosis and interstitial lung disease algorithms and validation estimates. Only five studies provided codes; none provided validation estimates. Because interstitial lung disease includes a broad spectrum of diseases, including pulmonary fibrosis, the scope of these studies varied, as did the corresponding diagnostic codes used. Research needs to be conducted on designing validation studies to test pulmonary fibrosis and interstitial lung disease algorithms and estimating their predictive power, sensitivity, and specificity. Copyright © 2012 John Wiley & Sons, Ltd.

Interstitial Fluid Flow Increases Hepatocellular Carcinoma Cell Invasion through CXCR4/CXCL12 and MEK/ERK Signaling

PubMed Central

2015-01-01

Hepatocellular carcinoma (HCC) is the most common form of liver cancer (~80%), and it is one of the few cancer types with rising incidence in the United States. This highly invasive cancer is very difficult to detect until its later stages, resulting in limited treatment options and low survival rates. There is a dearth of knowledge regarding the mechanisms associated with the effects of biomechanical forces such as interstitial fluid flow (IFF) on hepatocellular carcinoma invasion. We hypothesized that interstitial fluid flow enhanced hepatocellular carcinoma cell invasion through chemokine-mediated autologous chemotaxis. Utilizing a 3D in vitro invasion assay, we demonstrated that interstitial fluid flow promoted invasion of hepatocellular carcinoma derived cell lines. Furthermore, we showed that autologous chemotaxis influences this interstitial fluid flow-induced invasion of hepatocellular carcinoma derived cell lines via the C-X-C chemokine receptor type 4 (CXCR4)/C-X-C motif chemokine 12 (CXCL12) signaling axis. We also demonstrated that mitogen-activated protein kinase (MEK)/extracellular signal-regulated kinase (ERK) signaling affects interstitial fluid flow-induced invasion; however, this pathway was separate from CXCR4/CXCL12 signaling. This study demonstrates, for the first time, the potential role of interstitial fluid flow in hepatocellular carcinoma invasion. Uncovering the mechanisms that control hepatocellular carcinoma invasion will aid in enhancing current liver cancer therapies and provide better treatment options for patients. PMID:26560447

Facile Syntheses of Monodisperse Ultra-Small Au Clusters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bertino, Massimo F.; Sun, Zhong-Ming; Zhang, Rui

2006-11-02

During our effort to synthesize the tetrahedral Au20 cluster, we found a facile synthetic route to prepare monodisperse suspensions of ultra-small Au clusters AuN (N<12) using diphosphine ligands. In our monophasic and single-pot synthesis, a Au precursor ClAu(I)PPh3 and a bidentate phosphine ligand P(Ph)2(CH2)MP(Ph)2 (Ph = phenyl) are dissolved in an organic solvent. Au(I) is reduced slowly by a borane-tert-butylamine complex to form Au clusters coordinated by the diphosphine ligand. The Au clusters are characterized by both high resolution mass spectrometry and UV-Vis absorption spectroscopy. We found that the mean cluster size obtained depends on the chain length M ofmore » the ligand. In particular, a single monodispersed Au11 cluster is obtained with the P(Ph)2(CH2)3P(Ph)2 ligand, whereas P(Ph)2(CH2)MP(Ph)2 ligands with M = 5 and 6 yield Au10 and Au8 clusters. The simplicity of our synthetic method makes it suitable for large-scale production of nearly monodisperse ultrasmall Au clusters. It is suggested that diphosphines provide a set of flexible ligands to allow size-controlled synthesis of Au nanoparticles.« less

Evaluation of antitumor efficiency of experimental interstitial photodynamic therapy on the model of M1 sarcoma.

PubMed

Skugareva, O A; Kaplan, M A; Malygina, A I; Mikhailovskaya, A A

2009-11-01

Antitumor efficiency of interstitial photodynamic therapy was evaluated in experiments on outbred albino rats with implanted M-1 sarcoma. Interstitial photodynamic therapy was carried out using one diffusor at different output power and duration of exposure. The percentage of complete regression of the tumors increased with increasing exposure parameters.

Binomial outcomes in dataset with some clusters of size two: can the dependence of twins be accounted for? A simulation study comparing the reliability of statistical methods based on a dataset of preterm infants.

PubMed

Sauzet, Odile; Peacock, Janet L

2017-07-20

The analysis of perinatal outcomes often involves datasets with some multiple births. These are datasets mostly formed of independent observations and a limited number of clusters of size two (twins) and maybe of size three or more. This non-independence needs to be accounted for in the statistical analysis. Using simulated data based on a dataset of preterm infants we have previously investigated the performance of several approaches to the analysis of continuous outcomes in the presence of some clusters of size two. Mixed models have been developed for binomial outcomes but very little is known about their reliability when only a limited number of small clusters are present. Using simulated data based on a dataset of preterm infants we investigated the performance of several approaches to the analysis of binomial outcomes in the presence of some clusters of size two. Logistic models, several methods of estimation for the logistic random intercept models and generalised estimating equations were compared. The presence of even a small percentage of twins means that a logistic regression model will underestimate all parameters but a logistic random intercept model fails to estimate the correlation between siblings if the percentage of twins is too small and will provide similar estimates to logistic regression. The method which seems to provide the best balance between estimation of the standard error and the parameter for any percentage of twins is the generalised estimating equations. This study has shown that the number of covariates or the level two variance do not necessarily affect the performance of the various methods used to analyse datasets containing twins but when the percentage of small clusters is too small, mixed models cannot capture the dependence between siblings.

Assessment of thermal effects of interstitial laser phototherapy on mammary tumors using proton resonance frequency method

PubMed Central

Le, Kelvin; Li, Xiaosong; Figueroa, Daniel; Towner, Rheal A.; Garteiser, Philippe; Saunders, Debra; Smith, Nataliya; Liu, Hong; Hode, Tomas; Nordquist, Robert E.; Chen, Wei R.

2011-01-01

Laser immunotherapy (LIT) uses a synergistic approach to treat cancer systemically through local laser irradiation and immunological stimulation. Currently, LIT utilizes dye-assisted noninvasive laser irradiation to achieve selective photothermal interaction. However, LIT faces difficulties treating deeper tumors or tumors with heavily pigmented overlying skin. To circumvent these barriers, we use interstitial laser irradiation to induce the desired photothermal effects. The purpose of this study is to analyze the thermal effects of interstitial irradiation using proton resonance frequency (PRF). An 805-nm near-infrared laser with an interstitial cylindrical diffuser was used to treat rat mammary tumors. Different power settings (1.0, 1.25, and 1.5 W) were applied with an irradiation duration of 10 min. The temperature distributions of the treated tumors were measured by a 7 T magnetic resonance imager using PRF. We found that temperature distributions in tissue depended on both laser power and time settings, and that variance in tissue composition has a major influence in temperature elevation. The temperature elevations measured during interstitial laser irradiation by PRF and thermocouple were consistent, with some variations due to tissue composition and the positioning of the thermocouple's needle probes. Our results indicated that, for a tissue irradiation of 10 min, the elevation of rat tumor temperature ranged from 8 to 11°C for 1 W and 8 to 15°C for 1.5 W. This is the first time a 7 T magnetic resonance imager has been used to monitor interstitial laser irradiation via PRF. Our work provides a basic understanding of the photothermal interaction needed to control the thermal damage inside a tumor using interstitial laser treatment. Our work may lead to an optimal protocol for future cancer treatment using interstitial phototherapy in conjunction with immunotherapy. PMID:22191937

Effect of small versus large clusters of fish school on the yield of a purse-seine small pelagic fishery including a marine protected area.

PubMed

Hieu, Nguyen Trong; Brochier, Timothée; Tri, Nguyen-Huu; Auger, Pierre; Brehmer, Patrice

2014-09-01

We consider a fishery model with two sites: (1) a marine protected area (MPA) where fishing is prohibited and (2) an area where the fish population is harvested. We assume that fish can migrate from MPA to fishing area at a very fast time scale and fish spatial organisation can change from small to large clusters of school at a fast time scale. The growth of the fish population and the catch are assumed to occur at a slow time scale. The complete model is a system of five ordinary differential equations with three time scales. We take advantage of the time scales using aggregation of variables methods to derive a reduced model governing the total fish density and fishing effort at the slow time scale. We analyze this aggregated model and show that under some conditions, there exists an equilibrium corresponding to a sustainable fishery. Our results suggest that in small pelagic fisheries the yield is maximum for a fish population distributed among both small and large clusters of school.

Measurement of the spectral signature of small carbon clusters at near and far infrared wavelengths

NASA Technical Reports Server (NTRS)

Tarter, J.; Saykally, R.

1991-01-01

A significant percentage of the carbon inventory of the circumstellar and interstellar media may be in the form of large refractory molecules (or small grains) referred to as carbon clusters. At the small end, uneven numbers of carbon atoms seem to be preferred, whereas above 12 atoms, clusters containing an even number of carbon atoms appear to be preferred in laboratory chemistry. In the lab, the cluster C-60 appears to be a particularly stable form and has been nicknamed Bucky Balls because of its resemblance to a soccer ball and to geodesic domes designed by Buckminster Fuller. In order to investigate the prevalence of these clusters, and their relationship to the polycyclic aromatic hydrocarbons (PAHs) that have become the newest focus of IR astronomy, it is necessary to determine the spectroscopic characteristics of these clusters at near and far infrared wavelengths. Described here is the construction of a near to far IR laser magnetic resonance spectrometer that has been built at the University of California Berkeley in order to detect and characterize these spectra. The equipment produces carbon clusters by laser evaporation of a graphitic target. The clusters are then cooled in a supersonic expansion beam in order to simulate conditions in the interstellar medium (ISM). The expansion beam feeds into the spectrometer chamber and permits concentrations of clusters sufficiently high as to permit ultra-high resolution spectroscopy at near and far IR wavelengths. The first successful demonstration of this apparatus occurred last year when the laboratory studies permitted the observational detection of C-5 in the stellar outflow surrounding IRC+10216 in the near-IR. Current efforts focus on reducing the temperature of the supersonic expansion beam that transport the C clusters evaporated from a graphite target into the spectrometer down to temperatures as low as 1 K.

Structural effects in the interstitial solid solution system (La,Ce)(Fe,Si)13Cx-H: Correlation with hydrogenation kinetics

NASA Astrophysics Data System (ADS)

Hai, X.; Porcher, F.; Mayer, C.; Miraglia, S.

2018-02-01

Steady state and in-situ neutron powder diffraction on selected compositions of the magneto-caloric (La,Ce)(Fe,Si)13CxHy compounds has been used to locate the sites accommodated by the interstitial species and to reveal the structural modifications (breathing) that occur upon metal substitution and/or interstitial insertion. The latter type of measurement in which the sequential filling of interstitial sites is followed allows one to extract some useful hydrogenation kinetics data. This structural investigation has allowed to precise the deformations undergone by the complex metallic alloys La(Fe,Si)13 when subjected to light interstitial insertion or rare earth substitution at the cation site of the NaZn13-structure type. We attempt to correlate hydrogenation kinetics variations (depression or enhancement of the hydrogen absorption rate) with a particular inhomogeneous cell variation (breathing) and bonding of the NaZn13 structure-type.

Interstitial granulomatous dermatitis with arthritis.

PubMed

Long, D; Thiboutot, D M; Majeski, J T; Vasily, D B; Helm, K F

1996-06-01

Interstitial granulomatous dermatitis with arthritis is an uncommon systemic disorder involving the cutaneous and musculoskeletal systems. The eruption may mimic other dermatoses including granuloma annulare, erythema chronicum migrans, and the inflammatory stage of morphea. Key histopathologic characteristics, along with clinical correlation, allow accurate diagnosis. We describe the clinical, serologic, and histologic features in three patients with interstitial granulomatous dermatitis with arthritis. Skin biopsy specimens were examined and correlated with the clinical and laboratory findings. Erythematous, annular, indurated plaques on the extremities were present in two women. An erythematous, papular eruption on the head and neck was present in a third patient. All patients had myalgia and migratory polyarthralgias of the extremities along with various serologic abnormalities. Histologic examination revealed a dense lymphohistiocytic interstitial infiltrate involving primarily the reticular dermis. Foci of necrobiotic collagen were present. Vasculitis was absent. Interstitial granulomatous dermatitis with arthritis is unique multisystem disease with variable cutaneous expression. Abnormal serologic findings indicate a possible connection to collagen vascular disease.

Diffuse Alveolar Damage: A Common Phenomenon in Progressive Interstitial Lung Disorders

PubMed Central

Kaarteenaho, Riitta; Kinnula, Vuokko L.

2011-01-01

It has become obvious that several interstitial lung diseases, and even viral lung infections, can progress rapidly, and exhibit similar features in their lung morphology. The final histopathological feature, common in these lung disorders, is diffuse alveolar damage (DAD). The histopathology of DAD is considered to represent end stage phenomenon in acutely behaving interstitial pneumonias, such as acute interstitial pneumonia (AIP) and acute exacerbations of idiopathic pulmonary fibrosis (IPF). Acute worsening and DAD may occur also in patients with nonspecific interstitial pneumonias (NSIPs), and even in severe viral lung infections where there is DAD histopathology in the lung. A better understanding of the mechanisms underlying the DAD reaction is needed to clarify the treatment for these serious lung diseases. There is an urgent need for international efforts for studying DAD-associated lung diseases, since the prognosis of these patients has been and is still dismal. PMID:21637367

A hierarchical cluster analysis of normal-tension glaucoma using spectral-domain optical coherence tomography parameters.

PubMed

Bae, Hyoung Won; Ji, Yongwoo; Lee, Hye Sun; Lee, Naeun; Hong, Samin; Seong, Gong Je; Sung, Kyung Rim; Kim, Chan Yun

2015-01-01

Normal-tension glaucoma (NTG) is a heterogenous disease, and there is still controversy about subclassifications of this disorder. On the basis of spectral-domain optical coherence tomography (SD-OCT), we subdivided NTG with hierarchical cluster analysis using optic nerve head (ONH) parameters and retinal nerve fiber layer (RNFL) thicknesses. A total of 200 eyes of 200 NTG patients between March 2011 and June 2012 underwent SD-OCT scans to measure ONH parameters and RNFL thicknesses. We classified NTG into homogenous subgroups based on these variables using a hierarchical cluster analysis, and compared clusters to evaluate diverse NTG characteristics. Three clusters were found after hierarchical cluster analysis. Cluster 1 (62 eyes) had the thickest RNFL and widest rim area, and showed early glaucoma features. Cluster 2 (60 eyes) was characterized by the largest cup/disc ratio and cup volume, and showed advanced glaucomatous damage. Cluster 3 (78 eyes) had small disc areas in SD-OCT and were comprised of patients with significantly younger age, longer axial length, and greater myopia than the other 2 groups. A hierarchical cluster analysis of SD-OCT scans divided NTG patients into 3 groups based upon ONH parameters and RNFL thicknesses. It is anticipated that the small disc area group comprised of younger and more myopic patients may show unique features unlike the other 2 groups.

Low-temperature cluster catalysis.

PubMed

Judai, Ken; Abbet, Stéphane; Wörz, Anke S; Heiz, Ulrich; Henry, Claude R

2004-03-10

Free and supported metal clusters reveal unique chemical and physical properties, which vary as a function of size as each cluster possesses a characteristic electron confinement. Several previous experimental results showed that the outcome of a given chemical reaction can be controlled by tuning the cluster size. However, none of the examples indicate that clusters prepared in the gas phase and then deposited on a support material are indeed catalytically active over several reaction cycles nor that their catalytic properties remain constant during such a catalytic process. In this work we report turn-over frequencies (TOF) for Pd(n) (n = 4, 8, 30) clusters using pulsed molecular beam experiments. The obtained results illustrate that the catalytic reactivity for the NO reduction by CO (CO + NO --> 1/2N(2) + CO(2)) is indeed a function of cluster size and that the measured TOF remain constant at a given temperature. More interestingly, the temperature of maximal reactivity is at least 100 K lower than observed for palladium nanoparticles or single crystals. One reason for this surprising observation is the character of the binding sites of these small clusters: N(2) forms already at relatively low temperatures (400 and 450 K) and therefore poisoning by adsorbed nitrogen adatoms is prevented. Thus, small clusters not only open the possibility of tuning a catalytic process by changing cluster size, but also of catalyzing chemical reactions at low temperatures.

The Aftermath of a Suicide Cluster in the Age of Online Social Networking: A Qualitative Analysis of Adolescent Grief Reactions

ERIC Educational Resources Information Center

Heffel, Carly J.; Riggs, Shelley A.; Ruiz, John M.; Ruggles, Mark

2015-01-01

Although suicide clusters have been identified in many populations, research exploring the role of online communication in the aftermath of a suicide cluster is extremely limited. This study used the Consensual Qualitative Research method to analyze interviews with ten high school students 1 year after a suicide cluster in a small suburban school…

Properties of Diamond and Diamond-Like Clusters in Nanometric Dimensions

NASA Technical Reports Server (NTRS)

Halicioglu, Timur; Langhoff, Stephen R. (Technical Monitor)

1996-01-01

Variations in materials properties of small clusters of nanometric dimensions were investigated. Investigations were carried out for diamond and diamond-like particles in spherical shapes. Calculations were performed for clusters containing over 1000 carbon atoms. Results indicate that as the cluster size diminishes, (i) the average cohesive energy becomes weaker, (ii) the excess surface energy increases, and (iii) the value for stiffness decreases.

Derivatized gold clusters and antibody-gold cluster conjugates

DOEpatents

Hainfeld, J.F.; Furuya, F.R.

1994-11-01

Antibody- or antibody fragment-gold cluster conjugates are shown wherein the conjugate size can be as small as 5.0 nm. Methods and reagents are disclosed in which antibodies, Fab' or F(ab')[sub 2] fragments are covalently bound to a stable cluster of gold atoms. The gold clusters may contain 6, 8, 9, 11, 13, 55 or 67 gold atoms in their inner core. The clusters may also contain radioactive gold. The antibody-cluster conjugates are useful in electron microscopy applications as well as in clinical applications that include imaging, diagnosis and therapy. 7 figs.

The Distribution and Ages of Star Clusters in the Small Magellanic Cloud: Constraints on the Interaction History of the Magellanic Clouds

NASA Astrophysics Data System (ADS)

Bitsakis, Theodoros; González-Lópezlira, R. A.; Bonfini, P.; Bruzual, G.; Maravelias, G.; Zaritsky, D.; Charlot, S.; Ramírez-Siordia, V. H.

2018-02-01

We present a new study of the spatial distribution and ages of the star clusters in the Small Magellanic Cloud (SMC). To detect and estimate the ages of the star clusters we rely on the new fully automated method developed by Bitsakis et al. Our code detects 1319 star clusters in the central 18 deg2 of the SMC we surveyed (1108 of which have never been reported before). The age distribution of those clusters suggests enhanced cluster formation around 240 Myr ago. It also implies significant differences in the cluster distribution of the bar with respect to the rest of the galaxy, with the younger clusters being predominantly located in the bar. Having used the same setup, and data from the same surveys as for our previous study of the LMC, we are able to robustly compare the cluster properties between the two galaxies. Our results suggest that the bulk of the clusters in both galaxies were formed approximately 300 Myr ago, probably during a direct collision between the two galaxies. On the other hand, the locations of the young (≤50 Myr) clusters in both Magellanic Clouds, found where their bars join the H I arms, suggest that cluster formation in those regions is a result of internal dynamical processes. Finally, we discuss the potential causes of the apparent outside-in quenching of cluster formation that we observe in the SMC. Our findings are consistent with an evolutionary scheme where the interactions between the Magellanic Clouds constitute the major mechanism driving their overall evolution.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Luo, Langli; Su, Mao; Yan, Pengfei

The presence of water vapor, intentional or unavoidable, is crucial to many materials applications, such as steam generator, turbine engine, fuel cell, catalyst, and corrosion 1-6. Phenomenologically, water vapor has been noticed to accelerate oxidation of metals/alloys 7,8, however, the atomistic mechanisms remain elusive. Herein, through direct in situ atomic-scale transmission electron microscopy observation and density functional theory calculation, we reveal that water vapor enhanced oxidation of Ni-Cr alloy is associated with proton dissolution promoted vacancy formation, migration and clustering. Protons derived from water dissociation occupy interstitial position in the oxide lattice, which consequently leads to the lowering of bothmore » vacancy formation energy and the cation diffusion barrier. The atomic scale observations reveal a water vapor derived proton mediated oxide growth mechanism, which provides insights for reckoning many technological processes concerning materials in moist environment at elevated temperatures.« less

Structure of the SnO2(110 ) -(4 ×1 ) Surface

NASA Astrophysics Data System (ADS)

Merte, Lindsay R.; Jørgensen, Mathias S.; Pussi, Katariina; Gustafson, Johan; Shipilin, Mikhail; Schaefer, Andreas; Zhang, Chu; Rawle, Jonathan; Nicklin, Chris; Thornton, Geoff; Lindsay, Robert; Hammer, Bjørk; Lundgren, Edvin

2017-09-01

Using surface x-ray diffraction (SXRD), quantitative low-energy electron diffraction (LEED), and density-functional theory (DFT) calculations, we have determined the structure of the (4 ×1 ) reconstruction formed by sputtering and annealing of the SnO2(110 ) surface. We find that the reconstruction consists of an ordered arrangement of Sn3O3 clusters bound atop the bulk-terminated SnO2(110 ) surface. The model was found by application of a DFT-based evolutionary algorithm with surface compositions based on SXRD, and shows excellent agreement with LEED and with previously published scanning tunneling microscopy measurements. The model proposed previously consisting of in-plane oxygen vacancies is thus shown to be incorrect, and our result suggests instead that Sn(II) species in interstitial positions are the more relevant features of reduced SnO2(110 ) surfaces.

Investigating the role of small vent volcanism during the development of Tharsis Province, Mars

NASA Astrophysics Data System (ADS)

Richardson, J. A.; Bleacher, J. E.; Connor, C.; Connor, L.; Glaze, L. S.

2014-12-01

Clusters of tens to hundreds of small volcanic vents have recently been recognized as a major component of Tharsis Province volcanism. These volcanic fields are formed from distributed-style, possibly monogenetic, volcanism and are composed of low sloped edifices with diameters of tens of kilometers and heights of tens to hundreds of meters. We report a new catalog of these small volcanic vents, now available through the USGS Astrogeology Science Center. This catalog was created with the use of gridded topographic data from the Mars Orbiter Laser Altimeter (MOLA) and images from the Thermal Emission Imaging System (THEMIS) and the High Resolution Stereo Camera (HRSC). We are now investigating isolated clusters of distributed volcanism in Tharsis with this dataset. We hypothesize that these clusters are formed from significant magmatic events that played a large role in the development of Tharsis. Currently, the catalog contains 1075 unique volcanic vents in the Tharsis Province. With the catalog, potentially isolated volcano clusters are identified with vent density estimation. Vent intensity for clusters is found to be 1 vent per 1000 sq km or less. Crater retention rates for one such cluster, Syria Planum, indicates that these distributed volcanic systems might continue as long as 700 Ma, or that monogenetic volcanic systems overprint older systems. Using a modified basal outlining algorithm with MOLA gridded data, shield volumes are found to be between 1-20 cubic km. Current results show distributed-style volcanism occuring in Tharsis orders of magnitude more dispersed than analogous volcano clusers on Earth, while individual edifices are found to be an order of magnitude larger than volcanoes in Earth clusters. Proof of concept results are reported for three identified clusters: Arsia Mons Caldera, Syria Planum, and Southern Pavonis Mons.

Performance of small cluster surveys and the clustered LQAS design to estimate local-level vaccination coverage in Mali

PubMed Central

2012-01-01

Background Estimation of vaccination coverage at the local level is essential to identify communities that may require additional support. Cluster surveys can be used in resource-poor settings, when population figures are inaccurate. To be feasible, cluster samples need to be small, without losing robustness of results. The clustered LQAS (CLQAS) approach has been proposed as an alternative, as smaller sample sizes are required. Methods We explored (i) the efficiency of cluster surveys of decreasing sample size through bootstrapping analysis and (ii) the performance of CLQAS under three alternative sampling plans to classify local VC, using data from a survey carried out in Mali after mass vaccination against meningococcal meningitis group A. Results VC estimates provided by a 10 × 15 cluster survey design were reasonably robust. We used them to classify health areas in three categories and guide mop-up activities: i) health areas not requiring supplemental activities; ii) health areas requiring additional vaccination; iii) health areas requiring further evaluation. As sample size decreased (from 10 × 15 to 10 × 3), standard error of VC and ICC estimates were increasingly unstable. Results of CLQAS simulations were not accurate for most health areas, with an overall risk of misclassification greater than 0.25 in one health area out of three. It was greater than 0.50 in one health area out of two under two of the three sampling plans. Conclusions Small sample cluster surveys (10 × 15) are acceptably robust for classification of VC at local level. We do not recommend the CLQAS method as currently formulated for evaluating vaccination programmes. PMID:23057445

Polymorphism in magic-sized Au144(SR)60 clusters

DOE PAGES

Jensen, Kirsten M. O.; Juhas, Pavol; Tofanelli, Marcus A.; ...

2016-06-14

Ultra-small, magic-sized metal nanoclusters represent an important new class of materials with properties between molecules and particles. However, their small size challenges the conventional methods for structure characterization. We present the structure of ultra-stable Au144(SR)60 magic-sized nanoclusters obtained from atomic pair distribution function analysis of X-ray powder diffraction data. Our study reveals structural polymorphism in these archetypal nanoclusters. Additionally, in order to confirm the theoretically predicted icosahedral-cored cluster, we also find samples with a truncated decahedral core structure, with some samples exhibiting a coexistence of both cluster structures. Although the clusters are monodisperse in size, structural diversity is apparent. Finally,more » the discovery of polymorphism may open up a new dimension in nanoscale engineering.« less