Segregation Properties Research Articles

LSD alters dynamic integration and segregation in the human brain

Investigating changes in brain function induced by mind-altering substances such as LSD is a powerful method for interrogating and understanding how mind interfaces with brain, by connecting novel psychological phenomena with their neurobiological correlates. LSD is known to increase measures of brain complexity, potentially reflecting a neurobiological correlate of the especially rich phenomenological content of psychedelic-induced experiences. Yet although the subjective stream of consciousness is a constant ebb and flow, no studies to date have investigated how LSD influences the dynamics of functional connectivity in the human brain. Focusing on the two fundamental network properties of integration and segregation, here we combined graph theory and dynamic functional connectivity from resting-state functional MRI to examine time-resolved effects of LSD on brain networks properties and subjective experiences. Our main finding is that the effects of LSD on brain function and subjective experience are non-uniform in time: LSD makes globally segregated sub-states of dynamic functional connectivity more complex, and weakens the relationship between functional and anatomical connectivity. On a regional level, LSD reduces functional connectivity of the anterior medial prefrontal cortex, specifically during states of high segregation. Time-specific effects were correlated with different aspects of subjective experiences; in particular, ego dissolution was predicted by increased small-world organisation during a state of high global integration. These results reveal a more nuanced, temporally-specific picture of altered brain connectivity and complexity under psychedelics than has previously been reported.

Critical Properties of Segregation for Al1−xBix Liquid Binary Alloys

Critical properties of segregation for Al1−xBix liquid binary alloys are studied systematically using both static and dynamic effects. The static method involves thermodynamics of mixing such as en...

CARTECH Ti-3Al-8V-6Cr-4Mo-4Zr (BETA C)

Abstract CarTech Ti-3Al-8V-6Cr-4Mo-4Zr, also known as Ti-3-8-6-4-4 and Beta C, is a metastable beta alloy used in the solution heat treated or solution heat treated and aged condition. It is appropriate for applications where very high strength, minimum weight, and corrosion resistance are important. Ti-3Al-8V-6Cr-4Mo-4Zr has gained in popularity among beta alloys because it is easier to melt and process, exhibiting low segregation, good workability, and good heat-treating properties. This datasheet provides information on composition, physical properties, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: Ti-172. Producer or source: Carpenter Technology Corporation.

Atomic modeling of the segregation of vacancies on [formula omitted] dislocations in α-iron by diffusive molecular dynamics simulations

The interaction between dislocations and vacancies at finite temperature is crucial for many physical properties and phenomena in materials, such as vacancy segregation, strengthening effect, dislocation motion, and crystal plasticity. Conventional dislocation-vacancy interaction models use approximations based on elasticity theory and assumption that transition state energy can be deduced from the binding energy of the vacancies. The long-term vacancy diffusion near dislocation and the change of dislocation core induced by vacancy segregation are still difficult to capture. In this paper, we present the theoretical study on diffusion and segregation properties of vacancies near 111 edge or screw dislocation on slip planes of {110}, {112} and {123} in bcc iron. The calculations are performed with the distribution of vacancy concentration and dislocation-vacancy interaction energy as a function of distance from dislocation core using diffusive molecular dynamics (DMD). Meanwhile, the accompanying effects of the interaction on vacancy segregation, dislocation motion, and crystal plasticity are discussed. The vacancy diffusion near dislocation is a process highly anisotropic and inter-correlated towards equilibrium. The interaction of vacancies with the tensile stress field of edge dislocations is numerically stronger than that with the pure shear stress field of screw dislocations. The Peierls stress are calculated to reflect the effect of the vacancy segregation on dislocation motion. The slip planes of 111 dislocations have a significant influence on this interaction. With the slip planes changing from {110} to {123} to {112}, the absorption intensity of dislocation to vacancy and the ranges of the “effective interaction region” of both edge and screw dislocation decrease while the ranges of “absorption region” increases gradually. In addition, vacancy segregation produces a regulatory mechanism for the structure of dislocation core and promotes the transformation of dislocations on different slip planes to a more stable intermediate structure. This study visually presents the evolution of vacancies near dislocation, providing fundamental insights on the vacancy transport mechanisms which are essential for understanding dislocation-vacancy interaction, dislocation motion and plasticity of metallic materials.

Silicon separation and purification process from hypereutectic aluminum-silicon for organosilicon use

Industrial silicon is always used for the manufacture of organosilicon. This study evaluated the segregation properties of hypereutectic aluminum–silicon melts and revealed the silicon separation process from hypereutectic aluminum-silicon melts dealt with alternating electromagnetic directional solidification (AEM-DS). During the electromagnetic refining, the electromagnetic force can not penetrate Al–Si melts deeply and melts flow was generated by the outer thin surface, when the frequencies are 3, 30 and 50 kHz, the corresponding skin depths are 5.930, 1.876 and 1.027 mm, which show sharp attenuations. Moreover, the numerical simulation was used to simulate the electromagnetic field distribution. The experimental phenomenon can accord well with the simulation and calculation results. Moreover, this study reveal the middle process of hypereutectic Al–Si melt dealt with AEM-DS. The better separation effect will be helpful to eliminate Si, Al and acid waste in the following acid leaching.

The effect of a progressive taxation scheme on the endogenous formation of jurisdictions

AbstractThis paper analyzes the effect of a progressive taxation scheme on the segregative properties of the endogenous formation of jurisdictions. Households living in the same place form a jurisdiction which aims to produce a local public good and implement a redistribution policy by granting every household a demogrant of an amount determined by the jurisdiction. In every jurisdiction, production of local public services and the demogrant are financed with a local tax based upon the households wealth. Local wealth tax rates and the level of the demogrant are exogenously determined in every jurisdiction. Households are free to leave their jurisdiction for another jurisdiction that would provide them with their highest utility. We found that the existence of a demogrant seems to mitigate the segregative properties of endogenous jurisdiction formation, because the condition identified by Gravel and Thoron to ensure segregation of any stable jurisdiction structure remains necessary, but is no longer sufficient.

Enhanced 2.86 μm emission from a Ho,Pr:CaGdAlO4 crystal

The novel Ho,Pr:CaGdAlO4 crystal was grown successfully by the Czochralski method. The crystal structure, segregation, absorption and luminescence properties were investigated in detail. The concentration of Pr3+ and Ho3+ ions are 0.76 × 1020 cm−3 and 3.49 × 1020 cm−3, respectively. The effect of Pr3+ co-doping on the ~2.86 μm emission of Ho3+ was analyzed. The fluorescence intensity of Ho,Pr:CaGdAlO4 is three times higher than that of Ho:CaGdAlO4. The efficiency of energy transfer from Ho3+: 5I7 to Pr3+: 3F2 energy level was calculated to be 96.2%, which restrains the self-termination effect to a large extent in Ho,Pr:CaGdAlO4 crystal. The absorption cross-section at 1146 nm is 0.83 × 10−20 cm2 with the FWHM of 19 nm. The fluorescence branching ratio, emission cross-section and measured fluorescence lifetime at 2.86 μm are 12.7%, 2.38 × 10−20 cm2 and 0.194 ms, respectively. All these results suggest that Ho,Pr:CaGdAlO4 crystal is promising candidate for the 2.86 μm laser application pumped by the 1150 nm Raman fiber laser.

Dynamic properties of the two-dimensional density-driven segregation

We discuss some dynamic properties of the segregation in vertically vibrated binary granular mixtures with the same size. We present a method that can accurately calculate the order parameter in the simulation. By use of the time evolution of the order parameter, we have found that the convergence of the segregated state depends at least on the vibration amplitude, the total mass of the particles, and also the density difference between the lighter and heavier particles. The convergence is quicker for larger vibration amplitude, lighter total mass of the particles and more density difference between the lighter and heavier particles. We have also found that the fluctuation is larger even after the steady state is reached for lighter total mass of the particles and less density difference between the lighter and heavier particles.

Assessing the EDIP potential for atomic simulation of carbon diffusion, segregation and solubility in silicon melt

Molecular simulation based on empirical interatomic potential is an important tool in the study of impurity thermophysical properties, e.g. carbon diffusion, segregation and solubility in liquid silicon, which are key factors determining the carbon concentration and distribution during silicon crystal growth. The Tersoff potentials, although being very successful in describing many silicon and carbon properties, overestimate the silicon crystal melting temperature severely which incurs many criticism and restrictions when comparing the simulation results with experiments. In this study, the EDIP potential, which predicts an experimental comparable silicon melting temperature, was assessed whether it can reasonably capture the carbon diffusivity, segregation and solubility properties in silicon melt while avoiding the well-known temperature issue. We found that the EDIP potential, without requiring scaling the temperature, predicts consistent carbon and silicon diffusion coefficients with other potentials. The segregation coefficient estimated by EDIP is slightly higher than the experimental results. It fails in capturing the carbon solubility property by overestimating nearly two orders of magnitude higher than the experimental values. Based on potential energy and entropy calculation, we suggest that the problem of the EDIP potential is caused by the high entropy of the silicon melt phase. Overall, the research will provide useful information for other thermophysical studies based on EDIP potential and also be benefit to empirical potential optimization.

Trait-related changes in brain network topology in premenstrual dysphoric disorder

The female predominance in the prevalence of depression is partially accounted by reactivity to hormonal fluctuations. Premenstrual dysphoric disorder (PMDD) is a reproductive subtype of depression characterized by cyclic emotional and somatic symptoms that recur before menstruation. Despite the growing understanding that most psychiatric disorders arise from dysfunctions in distributed brain circuits, the brain's functional connectome and its network properties of segregation and integration were not investigated in PMDD. To this end, we examined the brain's functional network organization in PMDD using graph theoretical analysis. 24 drug naïve women with PMDD and 27 controls without premenstrual symptoms underwent 2 resting-state fMRI scans, during the mid-follicular and late-luteal menstrual cycle phases. Functional connectivity MRI, graph theory metrics, and levels of sex hormones were computed during each menstrual phase. Altered network topology was found in PMDD across symptomatic and remitted stages in major graph metrics (characteristic path length, clustering coefficient, transitivity, local and global efficiency, centrality), indicating decreased functional network segregation and increased functional network integration. In addition, PMDD patients exhibited hypoconnectivity of the anterior temporal lobe and hyperconnectivity of the basal ganglia and thalamus, across menstrual phases. Furthermore, the relationship between difficulties in emotion regulation and PMDD was mediated by specific patterns of functional connectivity, including connections of the striatum, thalamus, and prefrontal cortex. The shifts in the functional connectome and its topology in PMDD may suggest trait vulnerability markers of the disorder.

Effect of sintering temperatures on mixed phases and thermoelectric properties of nanostructured copper telluride

Abstract Nanostructured Copper Telluride was prepared by high energy ball milling method. The impact of sintering temperatures on phase segregation, structural, morphological and thermoelectric properties of Copper Telluride nanostructures were investigated by sintering the samples at various temperatures from 474 to 973 K. XRD patterns confirm the presence of mixed phases of Cu2.8Te2 and Cu7Te4 in the samples sintered at temperatures below 773 K, whereas pure phase of Cu2Te was observed in the sample sintered at temperatures higher than 773 K. The EDX data confirm the deficiency of Te content in the sample as a function of sintering temperatures. Due to high vapour pressure and volatile nature, part of Te may be released from copper telluride during high temperature sintering which resulted Te deficiency thereby phase change in the sample. The Seebeck coefficients of the samples increased with sintering temperature and the sample sintered at high temperatures (>773 K) exhibit relatively high seebeck coefficient compared to low temperature sintered samples (

Effect of In Situ Annealing on Phase Segregation And Optoelectronic Properties of Ultrasonic-Spray Deposited Polymer Blend Films

Here, we report a systematic study on the various effects of in situ annealing on nanoscale phase segregation and optoelectronic properties of ultrasonic spray deposited Poly (3-hexylthiophene) (P3HT): [6,6]-Phenyl-C71-butyric acid methyl ester (PC71BM) blend film and compared their photovoltaic properties with state-of-art spin-coated devices. Detailed investigations have been carried out to understand the structure-property relationship between the polymer crystallization process, film formation, and charge transport for such deposition technique. It has been found that ultrasonic spray coating at moderate substrate temperature, well below the solvent boiling point, results in the best quality films with comparable properties to spin-coated samples. Films deposited at 80 °C showed uniform crystallite size of approximately 8.6 nm, photoluminescence quenching around ∼98%, and improved charge transport properties with electron and hole mobility of 7.8 × 10−3 cm2 V−1 s−1 and 9.41 × 10−6 cm2 V−1 s−1, respectively. The photovoltaic devices obtained for such condition exhibited a power conversion efficiency of 2.45%. The similarities in film characteristics and device performances between spin and ultrasonic spray deposited samples indicate its practical feasibility as a scalable technique for large area applications.

A cell-cell repulsion model on a hyperbolic Keller-Segel equation.

In this work, we discuss a cell-cell repulsion model based on a hyperbolic Keller-Segel equation with two populations, which aims at describing the cell growth and dispersion in the co-culture experiment from the work of Pasquier etal. (Biol Direct 6(1):5, 2011). We introduce the notion of solution integrated along the characteristics, which allows us to prove the existence and uniqueness of solutions and the segregation property for the two species. From a numerical perspective, we also observe that our model admits a competitive exclusion principle which is different from the classical competitive exclusion principle for the corresponding ODE model. More importantly, our model shows the complexity of the short term (6days) co-cultured cell distribution depending on the initial distribution of each species. Through numerical simulations, we show that the impact of the initial distribution on the proportion of each species in the final population lies in the initial number of cell clusters and that the final proportion of each species is not influenced by the precise distribution of the initial distribution. We also find that a fast dispersion rate gives a short-term advantage while the vital dynamics contributes to a long-term population advantage. When the initial condition for the two species is not segregated, the numerical simulations suggest that asymptotic segregation occurs when the dispersion coefficients are not equal for two populations.

Stability, magnetic order, and electronic properties of ultrathin Fe3O4 nanosheets

We study the stability, magnetic order, charge segregation, and electronic properties of a novel three-layered Fe3O4 film by means of Hubbard-corrected density functional theory calculations. The stable film is predicted to consist of close-packed iron and oxygen layers, comprising a center layer with octahedrally coordinated Fe sandwiched between two layers with tetrahedrally coordinated Fe. The film exhibits an antiferromagnetic type I spin order. A charge analysis confirms that the stable structure has distinct charge segregation, with Fe2+ ions in the center layer and Fe3+ in the tetrahedral surface layers. Examination of the electronic band structures and densities of states shows that the bandgap is substantially reduced, from 2.4 eV for the bulk rocksalt to 0.3 eV for the film. The reduction in the bandgap is a consequence of the 2+ to 3+ change in oxidation state of Fe in the surface layers.

Distribution and particle-scale thermochemical property of biomass in the gasifier of a dual fluidized bed

Steam-gasification of biomass feedstock via dual fluidized bed has been proven to be an efficient and promising approach for the thermochemical conversion of biogenic fuels into the high-quality nitrogen-free syngas. However, very little is known about the actual behavior of the biomass fuels in the bed. In this work, the reactive gas-solid flow in a full-loop pilot-scale (1MWth) dual fluidized bed biomass gasifier is numerically simulated with the multiphase particle-in-cell approach. The aim of this study is to explore the species segregation and particle-scale thermochemical property of biomass material. The results show that the species segregation induced by the size and density differences gives rise to a preferential distribution of biomass material close to the bed surface. The undesired segregation phenomenon inhibits the sufficient mixing of biomass and heat carrier, and results in the particular distribution of thermochemical property of biomass material, which therefore requires further optimization of geometrical design. Lagrangian tracking of solid phase provides insight in the particle-scale thermochemical properties (i.e., temperature, heat transfer coefficient, carbon content) of biomass material. The observation of lognormal distribution and large value in the splash zone of biomass heat transfer coefficient enhances the understanding of the heat transfer behavior of biomass material. Biomass locating near the bed surface has the largest temperature. The promoting effect of wider size distribution of heat carrier on biomass dispersion provides a guidance for the process operation. The results of this study provide a fundamental understanding of the high-fidelity microscopic biomass property in the gasifier of dual fluidized bed, which will be beneficial for the optimization of the process designs.

Hydrotalcites with heterogeneous anion distributions: a first approach to producing new materials to be used as vehicles for the successive delivery of compounds

ABSTRACTHydrotalcites with heterogeneous distributions of anions between their layers were synthesized. Some synthesis parameters were studied to verify their influence on the anionic segregation properties of the hydrotalcites. The nature of the divalent cation and the crystallization method were most relevant. Zinc, in contrast to magnesium, assisted in discriminating carbonates and attracting nitrates to form hydrotalcites with heterogeneous distributions using microwave irradiation. Furthermore, the identification of this kind of hydrotalcite could be easily verified by determining the presence of a double reflection in the 003 X-ray diffraction (XRD) maximum, which definitively characterized a heterogeneous anion distribution. Finally, the reason as to why in some cases the hydrotalcite presented two reflections in the 003 XRD peak was elucidated.

Characterising avenin-like proteins (ALPs) from albumin/globulin fraction of wheat grains by RP-HPLC, SDS-PAGE, and MS/MS peptides sequencing

BackgroundWheat grain avenin-like proteins (ALPs) belong to a recently discovered class of wheat grain storage protein. ALPs in wheat grains not only have beneficial effects on dough quality but also display antifungal activities, which is a novel observation for wheat storage proteins. Previous studies have shown that ALPs are likely present in the albumin/globulin fractions of total protein extract from wheat flour. However, the accumulation characteristics of these ALPs in the mature wheat grain remains unknown.ResultsIn the present study, a total of 13 ALPs homologs were isolated and characterized in the albumin/globulin fractions of the wheat protein extract. A combination of multiple techniques including RP-HPLC, SDS-PAGE, MALDI-TOF and peptide sequencing were used for accurate separation and identification of individual ALP homolog. The C-terminal TaALP-by-4AL/7DS, TaALP-by-4AL/7AS/7DS, TaALP-bx/4AL/7AS/7DS, TaALP-ay-7DS, TaALP-ay-4AL, TaALP-ax-4AL, TaALP-ax-7AS, and TaALP-ax-7DS, were separated as individual protein bands from wheat flour for the first time. These unique ALPs peptides were mapped to the latest wheat genome assembly in the IWGSC database. The characteristic defence related proteins present in albumin and globulin fractions, such as protein disulfide-isomerase (PDI), grain softness protein (GSP), alpha-amylase inhibitors (AAIs) and endogenous alpha-amylase/subtilisin inhibitor were also found to co-segregate with these identified ALPs, avenin-3 and α-gliadins. The molecular weight range and the electrophoresis segregation properties of ALPs were characterised in comparison with the proteins containing the tryp_alpha_amyl domain (PF00234) and the gliadin domain (PF13016), which play a role in plant immunity and grain quality. We examined the phylogenetic relationships of the AAIs, GSP, avenin-3, α-gliadins and ALPs, based on the alignment of their functional domains. MALDI-TOF profiling indicated the occurrence of certain post-translations modifications (PTMs) in some ALP subunits.ConclusionsWe reported for the first time the complete profiling of ALPs present in the albumin/globulin fractions of wheat grain protein extracts. We concluded that majority of the ALPs homologs are expressed in wheat grains. We found clear evidence of PTMs in several ALPs peptides. The identification of both gliadin domain (PF13016) and Tryp_alpha_amyl domain (PF00234) in the mature forms of ALPs highlighted the multiple functional properties of ALPs in grain quality and disease resistance.

Development of a segregation model beyond McLean based on atomistic simulations

In the present atomistic study, layer-specific segregation to the surface is investigated for an exemplary (100) surface in iron–chromium alloys using an embedded-atom potential. Through a continuous variation of the chemical potential difference in the semi-grandcanonical ensemble, the full composition range is explored at temperatures between 600 K and 1400 K. The obtained layer-specific segregation curves demonstrate the well-known limitations of the widely used McLean model for interface segregation, i.e. a monolayer model imposing ideal behavior. However, keeping the original idea of McLean, the segregation model is extended in two ways in order to provide a complete analytical description of segregation: Firstly, the entire surface is hypothetically replaced by an equivalent single layer with identical segregation properties, which accounts for all subsurface layer effects, but also enables the application of an effective monolayer model with only one single energy of segregation. Secondly, directly following from the general treatment assuming non-ideal solution behavior, the energy of segregation becomes composition-dependent. The validity and accuracy of the proposed analytical model is confirmed by fitting the composition-dependent energy of segregation to the thermodynamically unambiguous solute excess. The change in surface formation energy according to the interfacial adsorption equation can be described excellently over the entire composition range for all investigated temperatures. The model can be applied to experimental data and directly transferred to grain boundaries.

Functionally Nb graded inconel 718 alloys fabricated by laser melting deposition: mechanical properties and corrosion behavior

Purpose Laser melting deposition (LMD) is an advanced additive manufacturing (AM) technology without powder waste, and nickel-based alloys with different Nb contents were created one-time by adjusting the ratio of mixed powders via a dual-feed system. Here, the authors provide a systematic report on the effects of the Nb content on the microstructure, Laves phase segregation and mechanical properties of as-received LMD nickel-based alloys. The effects of the Nb content on the microstructure, precipitation evolution and mechanical properties of the subsequent heat-treated LMD samples are also discussed in this paper. Design/methodology/approach Thus, the present research aims to obtain a better understanding of the effect of Nb content on the microstructural and mechanical properties of the as-received LMD Inconel 718 alloys through high-throughput sample fabrication. The microstructures were characterized by scanning electron microscopy and energy-dispersive spectroscopy, electron back-scattered diffraction and transmission electron microscopy methods. The mechanical properties were obtained from compressive tests and nano-indentation tests. Electrochemical tests, including electrochemical impedance spectroscopy and potentiodynamic polarizations, were carried out to evaluate the durability of the Inconel 718 alloys. Results can provide a factual basis for future applications of the functionally graded by AM technology. Findings The grain size of the as-received LMD Inconel 718 alloys decreased with the Nb content. The Laves phase distribution at the macro level was relatively uniform and the Laves phase exhibited a 1.5-fold nano-hardness compared with the matrix. The strength improvement for the as-received LMD Inconel 718 alloys with Nb content was attributed to grain refinement and enhancement of the Laves phase in terms of both hardness and content. Meanwhile, the corrosion resistance increased with the increase of the Nb content, especially for the pitting potential, which was attributed to the optimization of carbide precipitates due to the strong affinity between niobium and carbon. Originality/value The results provide a factual basis for the Nb content effect in LMD nickel-based alloys, and this method can greatly promote the development of new materials. The authors believe that this study makes a significant contribution to the literature and is suitable for publication.

Investigation of lead surface segregation during germanium–lead epitaxial growth

Crystalline germanium–lead (GePb) alloys were deposited on Ge(100) substrates via magnetron sputtering epitaxy. Strip-shaped Pb segregation along the direction was observed on the Ge0.976Pb0.024 film surface, as revealed by scanning electron microscopy. The chemical compositions and structural properties of the strip-shaped segregation were investigated by energy-dispersive X-ray spectroscopy, cross-sectional transmission electron microscopy and micro-Raman scattering spectra. The Ge0.976Pb0.024 film remained high crystal quality even after Pb segregation. The strip-shaped segregation was mainly composed of polycrystalline Pb, and its surface was covered with a GePb nanocrystalline layer.