Quasi-two-dimensional or hcp palladium nanoparticles with host-guest interaction prepared at room temperature

Quasi-two-dimensional palladium nanoparticles with an average lateral dimension of 7 nm have been prepared by reduction of a PdCl₂ graphite intercalation compound precursor by lithium-diphenylide in tetrahydrofuran at room temperature. Selected-area electron diffraction patterns provide evidence that the palladium nanoparticles are hcp single-crystal particles. Owing to the template effect of the graphite lattice, the lattice parameter of palladium was found to have a strong relation with the graphite, and a 3a _graphite superstructure was inferred. The palladium structure is rotated by 30^o with regard to the carbon host lattice. Raman spectroscopy on this sample showed that a charge transfer between carbon and palladium occurs. The sample can be considered as a common Pd-graphite intercalation compound with palladium nanoparticles as guest. This behaviour is different from palladium nanoparticles prepared by hydrogen reduction at higher temperatures from the same precursor material. These particles may represent an early stage of nanoparticle formation.     

Effects of load direction on the mechanical properties of open-cellular epoxy with a cubic prism structure

The mechanical properties of open-cellular epoxies with a cubic prism structure have been investigated by compressive tests with angles between the beam and the load direction of 0^o (90^o) and 45^o. When the angle was 45^o, the stress fluctuated in a plateau region about a roughly constant flow up to a strain of 77%. However, when the angle was 0^o (90^o), the flow stress changed significantly with the strain passing through a series of peaks. The absorption energy per unit volume was found to be essentially independent of the angle between the beam and the load direction.     

Density evolution during the growth of disc-shaped aluminium nanoparticles on a liquid surface

Aluminium (Al) nanoparticles (NPs) have been successfully fabricated on a liquid surface by thermal evaporation at room temperature. The Al NPs exhibit a disc-shaped morphology with mean diameter and height in the ranges 20–35 and 1.3–3.7?nm, respectively. As the nominal film thickness increases from 0.02 to 0.18?nm, the mean diameter and height are nearly independent of the thickness, implying that the density of the NPs increases during their growth. An explanation for this phenomenon is presented.     

Amorphization of cubic zirconia by caesium-ion implantation

Stabilized cubic zirconia is a promising candidate material for use as an inert fuel matrix for 'burning' excess Pu in light-water nuclear reactors. Zirconia is also considered to be an excellent nuclear waste form for direct geological disposal. Both applications are based on zirconia's high solubility for actinides, high chemical durability and high stability under irradiation. We report the first evidence of solid-state amorphization of yttria-stabilized cubic zirconia (YSZ) by 400keV Cs-ion implantation to 1 x 10²¹ ions m^-2 at room temperature. Amorphization of YSZ is caused by the large size incompatibility and low mobility of Cs ions in the YSZ structure, reflecting a relatively low solubility of Cs in YSZ. Nevertheless, the Cs concentration at which amorphization of YSZ occurred (about 8at.%) is well above the value that will typically be reached in an inert fuel matrix.     

The role of cognitive factors in body-size perception and recall-size estimation in normal-weight women

ObjectiveBased on the hypothesis that remembered body size differs from perceived body size, the objectives of this study were to assess the difference between body-size perception and recall size and to investigate the neuropsychological correlates of body-size estimation.MethodNinety-one normal-weight women were randomized into three body-size estimation conditions: photo-size estimation, mirror-size estimation and recall-size estimation without a photo or mirror. All participants first estimated the size of a neutral object, then adjusted distorted images of themselves according to experimental conditions. Finally, the participants completed the Trail Making Test (TMT) as a neuropsychological measure.ResultsBody-size estimations were influenced by the experimental condition in opposite directions for body-size perception and recall-size estimation. Participants who overestimated their body size took longer to complete the TMT-B, a measure of cognitive flexibility.ConclusionBody perception and body memory are clearly separable components of body image. An individual's amount of mental flexibility appears to be associated with body-size distortions, particularly body-size overestimations. Further research is needed on the nature of potential causal mechanisms for this phenomenon, including the use of relevant tests to explore cognitive flexibility and the effects of potentially confounding variables.     

Characterization of the aggregated phase in KCl:Cd2+ and KCl:Mn2+ by Raman spectroscopy

Abstract

The aggregated phase of the impurities in the systems KCl:Cd²⁺ and KCl:Mn²⁺ has been identified as the Suzuki phase by Raman spectroscopy. The linear increase in the integrated scattering intensities of the Raman lines with concentration of the impurities may be attributed to an increase in the mean precipitate size of the Suzuki phase.     

Conduction-electron mediated 1H nuclear spin-lattice relaxation in Ti45Zr38Ni17H x icosahedral quasicrystals

Nuclear magnetic resonance spin-lattice relaxation rates for ¹H in quasicrystalline Ti₄₅Zr₃₈Ni₁₇H _x are presented as a function of temperature and hydrogen concentration x. The temperature dependence demonstrates that the relaxation is via interaction with conduction electrons. The relaxation rate is extremely sensitive to hydrogen content, with the rate changing by a factor of as much as two for samples that differ in x     

Structure of a phase induced with Xe-ion irradiation-implantation in γ-TiAl

A phase transformation in γ-TiAl intermetallic alloy was found to be induced with 50keV Xe-ion irradiation-implantation at doses larger than 2.2 x 10¹⁸ ions m^-2 at room temperature. The structure and the chemical composition of the induced phase were investigated with high-resolution transmission electron microscopy and energy-dispersive X-ray spectroscopy. The zones of the induced phase have sizes up to about several tens of nanometres. The phase has a hexagonal structure with a = 0.286 nm and c = 0.462nm. The crystallographic orientation relationship between the phase (P) and the gamma-TiAl matrix is (001)_P//(111)_γ and \[100]_P//[011]_γ. The \[Al]/[Ti] atomic composition ratio in the phase is analysed to be 56/44, slightly different from that of the matrix, 51/49. These results suggest that the induced phase is an Al solid solution of α-Ti alloy phase, which has different structural parameters and chemical composition from those of the reported phase. It is suggested that the size of the ions is important in the phase transformation.     

Mental imagery increases self-determined motivation to exercise with university enrolled women: A randomized controlled trial using a peer-based intervention

ObjectivesThe purpose of this study was to examine the effects of a peer-based mental imagery intervention on the self-determined motivation and cardio-respiratory fitness of university enrolled women.DesignRandomized controlled trial.Method43 University enrolled women were randomized to peer-mentored or peer-mentored plus mental imagery conditions while 32 completed three meetings with peer-mentors and post-testing (M^age = 19.91; SD = 1.70).ResultsSignificant improvements in cardio-respiratory endurance, ratings of perceived endurance, and self-determined motivation to exercise were observed across both study conditions. Participants assigned to the peer mentored plus mental imagery condition reported significantly greater increases in self-determined motivation to exercise at post-test compared to those in the peer-mentored condition.ConclusionsPeer-based interventions are a viable way to improve fitness and health outcomes while mental imagery appears to be associated with increases in autonomous forms of exercise motivation.     

Changes in microstructure near the R-phase transformation in Ti50Ni48Fe2 studied by in-situ electron microscopy

Microstructural changes associated with the martensitic transformation from cubic (parent phase) to trigonal (R phase) which occurs with decreasing temperature in Ti₅₀Ni₄₈Fe₂ have been intensively studied by in-situ electron microscopy. Although the parent phase shows a characteristic microstructure with small domains, which are due to lattice modulation as a precursor to the transformation, their temperature dependence is contrasted with that of domains which appear below the transformation temperature in the R phase. The observations convince us that there is an essential difference between the natures of the domains observed in each state, and also reveal the formation of peculiar antiphase-like boundaries within a needle-like variant of the R phase. We also estimate the approximate size of the R phase just after nucleation and compare this with a theoretical consideration on the size of nuclei in martensites.     

Strain rate response of a Ni–Ti shape memory alloy after hydrogen charging

In this work, we investigate the susceptibility of Ni–Ti superelastic wires to the strain rates during tensile testing after hydrogen charging. Cathodic hydrogen charging is performed at a current density of 10?A/m² during 2–12?h in 0.9% NaCl solution and aged for 24?h at room temperature. Specimens underwent one cycle of loading-unloading reaching a stress value of 700 MPa. During loading, strain rates from 10^?6 to 5?×?10^?2?^?s^?1 have been achieved. After 8?h of hydrogen charging, an embrittlement has been detected in the tensile strain rate range of 10^?6 to 10^?4?s^?1. In contrast, no embrittlement has been detected for strain rates of 10^?3?s^?1 and higher. However, after 12?h of hydrogen charging and 24?h of annealing at room temperature, the embrittlement occurs in the beginning of the austenite-martensite transformation for all the studied strain rate values. These results show that for a range of critical amounts of diffused hydrogen, the embrittlement of the Ni–Ti superelastic alloy strongly depends on the strain rate during the tensile test. Moreover, it has been shown that this embrittlement occurs for low values of strain rates rather than the higher ones. This behaviour is attributed to the interaction between the diffused hydrogen and growth of the martensitic domain.     

Are perfectionism dimensions risk factors for anxiety symptoms? A meta-analysis of 11 longitudinal studies

Background: Over 50 years of theory and research implicates perfectionism in anxiety. However, it is unclear which (if any) perfectionism dimensions are risk factors for anxiety.

Objective: To address this, we conducted a meta-analysis testing whether socially prescribed perfectionism, concern over mistakes, doubts about actions, self-oriented perfectionism, and personal standards predict increases in anxiety.

Method: Our literature search yielded 11 relevant studies for inclusion, composed of children, adolescents, undergraduates, community adults, and psychiatric patients.

Results: Meta-analysis using random-effects models revealed concern over mistakes (r^+?=?.11), doubts about actions (r^+?=?.13), and personal standards (r^+?=?.08), but not socially prescribed perfectionism or self-oriented perfectionism, displayed significant small positive relationships with follow-up anxiety, after controlling for baseline anxiety.

Conclusion: Research is needed to understand the conditions under which the connection between perfectionism and anxiety becomes stronger (e.g., stress).     

Plastic deformation behaviour of decagonal Al70Ni15Co15 single quasicrystals

High-temperature deformation experiments have been performed on decagonal Al₇₀Ni₁₅Co₁₅ single quasicrystals at a constant strain rate of 10^-5s^-1 in the temperature range between 700 and 860°C. The samples were deformed in compression with the compression axis in different orientations, parallel to, inclined by 45° and perpendicular to the tenfold symmetry axis. Stress relaxation tests and temperature changes were carried out to determine thermodynamic activation parameters. The flow stress and the activation enthalpy were found to depend on the sample orientation whereas dependences of the activation volume and the stress exponent on the orientation were not observed. Additionally, deformation tests were performed on samples of the basic Co-rich modification of the decagonal phase at the temperature of 860°C in the same three orientations. The deformation behaviours of the two different modifications of the decagonal phase are discussed.     

A meta-analysis of the effectiveness of the low-ball compliance-gaining procedure

IntroductionThe low-ball (Cialdini et al., 1978)¹ is a compliance-gaining technique consisting of making an attractive initial offer to get a person to agree to the request and then making the terms less favorable (target request).Objective and methodsThe effectiveness of this technique was evaluated in a meta-analysis using 17 references, 23 studies, 44 subgroups and a combined sample size of 4733.ResultsAnalysis reported a weighted mean correlation coefficient of r = .16 and a weighted mean odds ratio of OR = 2.47. Moderator analysis reported that the low-ball was more efficient with a high cost request in terms of effort for the participant and when the solicitation of the target request is deferred.ConclusionThese findings appeared congruent with commitment theoretical explanation of the low-ball.     

Kinetics of photoinduced changes in Ag nanoparticles deposited on an indium tin oxide surface

An enhancement of the UV-visible optical absorption spectra of Ag nanoparticles (NPs) deposited on indium tin oxide (ITO) surfaces of different resistance by a seed-mediated growth technique is presented. A bicolour coherent beam, obtained from a pulsed Nd:YAG laser providing a 1060-nm fundamental wavelength and a double-frequency one at 530?nm, was used. A significant change in the optical density is observed for Ag NPs on low-resistance ITO surfaces (≈4?Ω/square), while almost nothing occurs with high-resistance (≈50?Ω/square surfaces). The spectral position of the maximal absorption at 440?nm is almost preserved in both cases. This result is explained in terms of a local photoinduced static field and surface-plasmon polaritons interacting with photoexcited phonons. A grating effect, arising from the coherent bicolour light forming a superstructure as for quantum crystals, could be another contribution.     

Electron irradiation damage in SnO

In a study of radiation effects in SnO we have found that electron-beam damage is observable from changes in a high-resolution electron microscopy image or electron diffraction pattern. The early stage of the damage is not accompanied by a change in composition or a loss of crystallinity. The dose required for this damage (about 600 C cm^?2) is approximately independent of electron energy (between 100 and 400 keV) and specimen temperature (between 100 and 300 K). The damage is believed to start with displacement of oxygen atoms from their lattice position through a radiolytic mechanism with an efficiency of approximately 10^?4.     

The order–dsorder transition at twin boundaries in Cu3Au as studied by TEM

Abstract

The order-disorder phase transition at ∑ = 3{111}- and {211}-type twin boundaries has been studied in the L1²-ordered alloy Cu³Au employing in situ heating in a transmission electron microscope. Evidence is presented for an order-disorder phase transition occurring in these boundaries prior to the bulk transition. The temperature difference ΔT between the transition temperature of both boundary types and the bulk is estimated as 0.5K <ΔT<2K. No difference in T _c for the twin boundaries can be established as yet. The nature of the order-disorder transition in both twin boundaries is presumably a second-order phase transition.     

A molecular dynamics study of atom mobility on steps of a Si(100) surface

Thermally activated motions of atoms on steps of a Si(100) surface have been studied using molecular dynamics simulations with standard three-body potentials. In the temperature interval 100-450K, these motions have two salient characteristics: firstly, a growth rate t^m leading to displacements of 1A in some tens of picoseconds and secondly, a marked dependence on the step morphology. These results are discussed in the light of experimental observations of step dynamics.     

Dislocation relaxation in aluminium single crystals at 10 MHz frequency

Abstract

Dislocation relaxation, namely the Bordoni peak, in the three principal planes of a high-purity aluminium single crystal has been studied by measuring the ultrasonic attenuation of longitudinal waves at a frequency of 10 MHz using a conventional ultrasonic single-ended pulse-echo technique. The crystals of <100>, <110>, or <111> orientation were deformed by compression, and the temperature dependence of the ultrasonic attenuation was measured after applying resolved shear stresses ranging up to 60N mm^?2. The results lead to the following conclusions: (i) The temperature of the Bordoni peak is essentially independent of the orientation; (ii) the temperature of the peak decreases up to a resolved shear stress near 28 N mm^?2 and then increases slightly for higher prior stresses; (iii) the peak height increases with increasing deformation; and (iv) a subsidiary peak at the lower temperature side of the Bordoni peak (the Niblett-Wilks peak) appears only at low deformations.     

Spontaneous atom mixing and unmixing in metallic nanoparticles

The behaviour of atom mixing and unmixing in metallic nanoparticles has been studied in situ by transmission electron microscopy, using particles in the Au₂Pb-Sn system. It is confirmed that not only spontaneous mixing but also spontaneous unmixing take place in Au₂Pb particles. At room temperature, spontaneous mixing of tin atoms into Au₂Pb particles takes place, and this mixing induces unmixing of lead from Au₂Pb, resulting in the formation of AuSn particles accompanied by lead precipitates.