Investigation of the thermo-stimulated surface segregation in the ternary Co-Cr-Mo alloy by means of Ionization Spectroscopy

Ionization Spectroscopy has been used to study thermo-induced surface segregation in the near-surface region of the ternary Co-Cr-Mo alloy. For the non-annealed alloy the Mo atoms preferred segregation in the outermost layers and Cr atoms segregation in the underlying layers of surface was observed at room temperature. Heating of the alloy promotes increasing of Co concentration and decreasing of Mo concentration in the near-surface region. For the annealed alloy the insignificant Mo atoms segregation on the outermost layers and enrichment with Co and Cr atoms in underlayers are displayed. The present results are compared with several theories of segregation.     

Low energy electron induced characteristic losses in the Fe73.6Cu1Nb2.4Si15.8B7.2 (FINEMET) alloy surface

Electron Energy Loss Spectroscopy has been employed for investigation of the electronic states of amorphous and crystalline Fe_73.6Cu₁Nb_2.4Si_15.8B_7.2 (FINEMET) alloy surface and alloy components. Electron energy losses have been measured for primary electron beam energies E₀ from 150 to 650 eV. The characteristic energy loss spectra were composed of main peaks which we have interpreted due to surface and bulk plasmons, a combination of surface and bulk losses, high harmonics of plasma losses, inter-band transitions and ionization of core levels. The measured energies for the plasmon excitations were found not to agree with calculated values according to the classical theory for the collective oscillations in solids. Changes in the intensity lines of the surface and bulk plasmons were observed for all specimens depending on primary electron energy E₀. The present results are compared with characteristic energy loss data reported in the literature.     

Spatially Resolved Analytical Electron Microscopy at Grain Boundaries of а-Al2O3

In this work the electronic structure and the impurity excess of the basal and rhombohedral twin grain boundaries are investigated, using electron energy loss spectroscopy (EELS) and energy dispersive X-ray spectroscopy (EDXS).The measurability of electronic structures of the twin grain boundaries are discussed by comparing theoretical density of states (DOS) from bulk material with interfacial DOS, obtained from local density functional theory (LDFT)calculations.     

One-pot mechanical synthesis of the nanocomposite granule of LiCoO2 nanoparticles

The layered rock-salt LiCoO₂ granules consisted of the primary nanoparticles were successfully synthesized by one-pot mechanical method without external heating. The sizes of the primary nanoparticle and the granule observed using electron microscopy were 50–200 nm and 20 μm, respectively. The surface property of the primary nanoparticle was evaluated by STEM-EELS, which revealed that the primary particle possesses the lithium defective part at the surface. The penetration behavior of an electrolyte into the granule was also evaluated by STEM-EDX, which indicated that the electrolyte could not fully penetrate into the granule. The first charge and discharge capacities of Li-ion cell assembled with the synthesized LiCoO₂ granules were 140 and 120 mA h/g, respectively. The relationship between the particle structures of the synthesized LiCoO₂ granules and the electrochemical properties were discussed.     

Microstructural characterization of terbium-doped ceria

The microstructures of Ce_1−xTb_xO_2−δ (0.10 ≤ x ≤ 0.50) sintered samples were studied systematically using transmission electron microscopy. The sintered samples consist of not only fluorite-structured matrix but also nano-sized precipitates. Correspondingly, diffuse scattering and extra reflections related to the precipitates were observed in the selected area diffraction patterns. The composition of the precipitates was studied quantitatively by electron energy-loss spectroscopy, indicating that the precipitates have higher Tb concentration than that of the matrix. Furthermore, Tb³⁺ and Ce³⁺ cations were observed to segregate in the precipitates.     

EELS and AES investigation of Rh thin film growth on polycrystalline Al substrate

A Rh/Al model catalyst was prepared by depositing rhodium atoms onto polycrystalline aluminium substrates. The plasmon loss associated with the Al (LMM) Auger peak was measured and the plasmon gain was successfully resolved. The loss channel at 16-17 eV which occurs in electron energy loss spectroscopy (EELS) as well as in Auger electron spectroscopy (AES) was established to be a Rh 4 d→p transition. The spectral shape of the Rh N_2,3 (4p) states generated by inner-shell transitions, is identical in both samples (polycrystalline Rh foil and Rh deposited onto Al foil), suggesting similar local electronic environment for Rh atoms although the macroscopic electronic structure of these samples are essentially different. The dramatic changes found during the sample heating and CO adsorption/desorption experiments by AES and TDS can be correlated to EELS results showing a gradual suppression of plasmon losses characteristic of Rh and an increase of the concentration of nearly free electrons at the surface. A Rh-Al alloy is probably formed on the surface after annealing to 673 K.     

Chemical and photoluminescence analyses of new carbon-based boron oxynitride phosphors

Analyses of newly developed carbon-based boron oxynitride phosphors using an electron energy-loss spectrometer and a spectroflurophotometer were carried out. The results showed that the prepared phosphor powder has covalently bonded boron, nitrogen, and oxygen atoms with a soft carbon framework. Photoluminescence characterization revealed that the resultant phosphor has a direct bandgap transition with defect broadened band edges, resulting in a high quantum efficiency, because the atomic distances of the phosphor are smaller than those of conventional carbon-based boron nitride compounds, which have an indirect bandgap transition and a low quantum efficiency. The atomic distances of the phosphor are smaller owing to the presence of oxygen atoms, which have a higher electron affinity and a smaller covalent bond radius compared with boron, carbon and nitrogen.     

A localized surface plasmon resonance based immunosensor for the detection of casein in milk

In this research, a localized surface plasmon resonance (LSPR) immunosensor based on gold-capped nanoparticle substrate for detecting casein, one of the most potent allergens in milk, was developed. The fabrication of the gold-capped nanoparticle substrate involved a surface-modified silica nanoparticle layer (core) on the slide glass substrate between bottom and top gold layers (shell). The absorbance peak of the gold-capped nanoparticle substrate was observed at ∼520 nm. In addition, the atomic force microscopy (AFM) images demonstrated that the nanoparticles formed a monolayer on the slide glass. After immobilizing anti-casein antibody on the surface, our device, casein immunosensor, could be applied easily for the detection of casein in the raw milk sample without a difficult pretreatment. Under the optimum conditions, the detection limit of the casein immunosensor was determined as 10 ng/mL. Our device brings several advantages to the existing LSPR-based biosensors with its easy fabrication, simple handling, low-cost, and high sensitivity.     

A localized surface plasmon resonance based immunosensor for the detection of casein in milk

In this research, a localized surface plasmon resonance (LSPR) immunosensor based on gold-capped nanoparticle substrate for detecting casein, one of the most potent allergens in milk, was developed. The fabrication of the gold-capped nanoparticle substrate involved a surface-modified silica nanoparticle layer (core) on the slide glass substrate between bottom and top gold layers (shell). The absorbance peak of the gold-capped nanoparticle substrate was observed at ～520 nm. In addition, the atomic force microscopy (AFM) images demonstrated that the nanoparticles formed a monolayer on the slide glass. After immobilizing anti-casein antibody on the surface, our device, casein immunosensor, could be applied easily for the detection of casein in the raw milk sample without a difficult pretreatment. Under the optimum conditions, the detection limit of the casein immunosensor was determined as 10 ng/mL. Our device brings several advantages to the existing LSPR-based biosensors with its easy fabrication, simple handling, low-cost, and high sensitivity.     

Synthesis of boron nitride nanotubes with SiC nanowire as template

A novel template method for the preparation of boron nitride nanotubes (BNNTs) using SiC nanowire as template and ammonia borane as precursor is reported. We find out that the SiC nanowires could be effectively etched out by the vapors decomposed from ammonia borane, leading to the formation of BNNTs. The as-prepared products are well characterized by means of complementary analytical techniques. A possible formation mechanism is disclosed. The method developed here paves the way for large scale production of BNNTs.     

Theoretical assessment of a highly sensitive photonic crystal fibre based on surface plasmon resonance sensor operating in the near-infrared wavelength

A surface plasmon resonance (SPR) sensor comprising a photonic crystal fibre (PCF) with an annular analyte channel outside the fibre is described and analysed. The losses of the sensor are analysed by the finite element method (FEM) with the boundary condition of a perfectly matched layer (PML). The influence of the structural parameters on the performance of the sensor is investigated based on the loss spectra of the fundamental mode. The relationship between the resonance wavelengths and analyte refractive indexes is established for refractive indexes ranging from 1.395 to 1.425. An average spectral sensitivity of 12,592.86?nm/RIU can be achieved in the sensing range corresponding to a resolution of 7.94×10^?6?RIU. The maximum spectral sensitivity and the maximum figure of merit (FOM) are as high as 22,807.14?nm/RIU and 595.78, respectively.     

Synthesis and crystal structure of Cu2NiO(B2O5) and Cu2MgO(B2O5)

A transport reaction synthesis technique has been used to prepare single crystals of two pyroborate compounds having the formulas Cu₂NiO(B₂O₅) and Cu₂MgO(B₂O₅). The two compounds are isostructural and crystallize in the monoclinic space group P2₁/c. Cu₂NiO(B₂O₅): a=3.2003(10), b=14.775(3), c=9.097(3), β=93.28(4), V=429.4(2) Å³, Z=4; and Cu₂MgO(B₂O₅): a=3.2401(6), b=14.790(2), c=9.147(2), β=94.88(2), V=436.7(2) Å³, Z=4. The structures of Cu₂NiO(B₂O₅) and Cu₂MgO(B₂O₅) were, respectively, refined from 804 and 1000 independent reflections to the final residuals R1=0.0366, wR2=0.0911 and R1=0.0231, wR2=0.0644. Both compounds exhibit a chevron-like structure built up of ribbons, made of edge-connected copper and nickel-oxygen polyhedra, running along the (1 0 0) direction. These ribbons are connected from one another via oxygen atoms and the cohesion of the three-dimensional network is ensured by [B₂O₅] entities. Cu in part occupies the position for Ni or Mg, so that the compounds actually are solid solution compounds. Ni or Mg atoms are octahedrally coordinated by oxygen, while the two pure Cu sites show [4] and [4+1] coordination, for Cu(1) and Cu(2), respectively. The ELNES B-K edge spectra for the two compounds support that the borate group present is [B₂O₅].     

Complex investigation of electronic structure transformations in Lead Sulphide nanoparticles using a set of electron spectroscopy techniques

It has been reported recently that kinetic energy of photoelectrons emitted from core levels decreases with decreasing of the nanocrystal size. This phenomenon is called the size shift. The size shift value is the same for donor and acceptor in the compound. The present work is aimed on the explanation of this phenomenon. Crystals of lead sulfide PbS with different size from 50 to 350 nm were grown by chemical bath deposition (CBD) technique from alkaline solution onto Si and GaAs substrates. The morphology and size of crystals were analyzed by high resolution scanning electron microscopy (HRSEM). Complex electron spectroscopy investigations of electronic structure were carried out. In recent experiments X-ray photoelectron spectroscopy (XPS) was used for determination of Pb 4f, and S 2p electronic level positions and their size shifts. To explain the observed dependences in this work, we applied the following methods: analysis of PbS valence band (VB) and Pb 5d electronic level structure in the range ∼0-30 eV by XPS, high resolution electron energy losses spectroscopy (HREELS) for analysis of band gap transformations and work function measurements by Kelvin probe microscopy for the contact potential difference (CPD). The influence of work function increasing, widening of the band gap, transformations in VB and inter-level energy distances with decreasing of nanocrystal size on the size shift function ΔE(R) is discussed.     

Simplified model for the fatigue growth analysis of surface cracks in round bars under mode I

The fatigue growth of an edge flaw in a round bar under cyclic tension or bending loading is examined, using a two-parameter numerical model. First, it is shown that the crack front evolution is defined by a very small number of parameters, which varies during crack growth. Approximated solutions for both the crack propagation path and the stress intensity factor are derived, and the fatigue predictions using this simple analytical method are finally compared with the numerical results.     

Microstructure, chemistry and coating properties of ion-plated TiN on type 304 stainless steel

Characterization of TiN coatings on type 304 stainless steel was carried out using a Zeiss EM 902A energy filtering transmission electron microscope equipped with an electron energy loss spectroscopy (EELS) detector. TiN thin films were produced by a hollow cathode discharge ion plating coater. It was found by plan-view transmission electron microscopy that the microstructure of the TiN coatings is thickness dependent. The grain size of TiN ranges from 88 nm at the coating surface down to 9 nm near the TiN/steel interface. In addition, the TiN surface layer shows some degree of texture, but the subsurface and internal TiN layers are mainly equiaxial and randomly oriented. Chemical analysis by EELS shows that the relative oxygen content increases linearly from the TiN surface to the TiN/steel interface, whereas the relative nitrogen content first decreases slowly and then drops rapidly near the interface. The presence of a Ti₂N phase and the deficiency of nitrogen near the TiN/steel interface suggest that the early-deposited TiN is nonstoichiometric. By the periodic cracking method, the ultimate shear stress at the TiN/steel interface and the residual stress in the TiN thin film were estimated to be 2.2 GPa and 12.8 GPa, respectively.     

Impact Assessment: assessing the social dimensions of fisheries research projects in the Asia-Pacific Region

Interest in understanding the social impact of publicly funded science research is growing globally. However, practical examples demonstrating how the social impacts of research for development are measured are negligible. This paper illustrates the utility of Impact Assessment (IA), Social Impact Assessment (SIA) in particular to measure and articulate the social dimensions of research for development. We employed substantive aspects of SIA to assess the social impacts of the Australian Centre for International Agricultural Research (ACIAR) funded fisheries research projects across Southeast Asia and the Pacific Island Countries. Data were collected through a survey, in-depth interviews, and case studies. Results illustrate that SIA can offer a nuanced understanding of the contribution of research for development to changes in culture, community health and wellbeing, livelihood and economy, and governance and politics, among others. We suggest that researchers, policymakers and research for development organisations consider incorporating SIA in their projects not only as a tool to assess impact but also as a process to manage and understand the social dimensions of science research.     

Evaluation of fundamental and functional properties of natural plant product powders for direct compaction based on multivariate statistical analysis

Direct compaction (DC) is the preferred choice for tablet manufacturing; however, its application in natural plant product (NPP) tablets is still extremely immature. In this study, NPP powders prepared by three commonly used methods were evaluated on their suitability for DC. Extensive characterizations of their physical properties were performed. Multivariate statistical analysis was utilized to explore the influence of preparation technology on the properties of NPP powders and identify the dominating factors that influence their DC properties. The results demonstrated that (i) the 27 kinds of model NPP powders selected randomly in this study could to some degree represent most NPP powders used in actual production; (ii) ～81.5% of the NPP powders exhibited both poor compactibility and flowability, and none of the NPP powders could be compacted into tablets via DC; (iii) the physical properties of NPP powders prepared by direct pulverization were significantly different from those of extracted ones, while there were no significant differences between the water and ethylalcohol extracted ones; and (iv) the DC properties of NPP powders could be improved through controlling some physical properties (e.g., density, particle size, morphology, and texture parameters) reasonably. Overall, this study comprehensively evaluated the current status and application of NPP powders in DC, and is significant in facilitating the development and modernization of NPPs through DC.     

Advances in metals and alloys for joint replacement

Metals, ceramics, polymers, and composites have been employed in joint arthroplasty with ever increasing success since the 1960s. New materials to repair or replace human skeletal joints (e.g. hip, knee, shoulder, ankle, fingers) are being introduced as materials scientists and engineers develop better understanding of the limitations of current joint replacement technologies. Advances in the processing and properties of all classes of materials are providing superior solutions for human health. However, as the average age of patients for joint replacement surgery decreases and the average lifespans of men and women increases worldwide, the demands upon the joint materials are growing. This article focuses solely on advances in metals, highlighting the current and emerging technologies in metals processing, metal surface treatment, and integration of metals into hybrid materials systems. The needed improvements in key properties such as wear, corrosion, and fatigue resistance are discussed in terms of the enhanced microstructures that can be achieved through advanced surface and bulk metal treatments. Finally, far reaching horizons in metals science that may further increase the effectiveness of total joint replacement solutions are outlined.