Enlarged ferromagnetic hysteresis in InMnP:Be epilayers formed by thermal diffusion using MBE-grown Mn/InP:Be bilayers

The p-type InMnP:Be epilayers, which were prepared by thermal diffusion of Mn through in-situ deposition of Mn layer using molecular beam epitaxy (MBE) onto MBE-grown InP:Be epilayers and subsequent in-situ annealing at 300–350 °C, were investigated. InMnP:Be epilayers prepared by the above sequence clearly showed the Mn-related emission band at 1.1–1.2 eV, which indicates the effective incorporation of Mn²⁺ ions into the host layer InP:Be. The samples demonstrated very large ferromagnetic hysteresis loops with enhanced coercivity, and the ferromagnetic-to-paramagnetic transition of the samples was observed to occur at ∼85 K. These results suggest that InP-based ferromagnetic semiconductor layers having enhanced ferromagnetism can be effectively formed by the above-mentioned sequential in-situ processes.     

Quantum-dot-sensitized solar cells fabricated by the combined process of the direct attachment of colloidal CdSe quantum dots having a ZnS glue layer and spray pyrolysis deposition

We were able to attach CdSe quantum dots (QDs) having a ZnS inorganic glue layer directly to a mesoporous TiO(2) (mp-TiO(2)) surface by spray coating and thermal annealing. Quantum-dot-sensitized solar cells based on CdSe QDs having ZnS as the inorganic glue layer could easily transport generated charge carriers because of the intimate bonding between CdSe and mp-TiO(2). The application of spray pyrolysis deposition (SPD) to obtain additional CdSe layers improved the performance characteristics to V(oc) = 0.45 V, J(sc) = 10.7 mA/cm(2), fill factor = 35.8%, and power conversion efficiency = 1.7%. Furthermore, ZnS post-treatment improved the device performance to V(oc) = 0.57 V, J(sc) = 11.2 mA/cm(2), fill factor = 35.4%, and power conversion efficiency = 2.2%.     

Surface characterization and dissolution study of biodegradable calcium metaphosphate coated by sol–gel method

Coatings of biomedical implant surfaces by a bioactive calcium phosphate film render bioactivity to the implant surface and shorten the healing time. In this present study, calcium metaphosphate (CMP) sol was synthesized by sol–gel method and coated onto the titanium alloys (Ti-6Al-4V). CMP sol was first synthesized by reacting Ca(NO₃)₂4H₂O (Sigma–Aldrich 99%, USA) with (OC₂H₅)₃P (Fluka 97%, Japan) in methyl alcohol. A stoichiometric Ca/P ratio of 0.5 was obtained by varying the amounts of the reactants. Sol was then coated on Ti-6Al-4V substrates by spin coating. The coated-specimens were then dried at 70 °C for 24 h, followed by a heat treatment at 650 °C for 1 h. Structural and chemical properties of the coatings were evaluated using XRD, SEM, and EPMA. The dissolution property of the coated-CMP layer was investigated by immersing the samples in the simulated body fluid (SBF) for 1, 3, 7 and 21 days. The concentration of Ca²⁺ released was measured using ICP. After heat treatment, SEM indicated a smooth and uniform CMP layer, with CMP grains of approximately 100 nm. The CMP phase was identified with δ-CMP (JCPDS #9-363). After immersion in SBF, coatings were observed to be roughened and porous. The concentration of Ca²⁺ in SBF was observed to increase over time, indicating continuous dissolution. The presence of titanium oxide phosphate compounds were also observed on CMP surfaces after immersion. It was thus concluded that the ability to control coating properties as well as the need for low heat treatment temperature offers advance for the use of CMP coating by sol–gel process on Ti-6Al-4V implant surfaces.     

Enhancement of cyclability using recombination reaction of Cu for Sn2Fe nanocomposite anode for lithium-ion batteries

A Sn₂Fe/C nanocomposite containing Cu was evaluated as an anode material for rechargeable lithium-ion batteries. The electrochemical reaction mechanism of this nanocomposite was examined by ex-situ X-ray diffraction and high resolution transmission electron microscopy. The Sn₂Fe/C nanocomposite containing Cu showed dramatically improved cycling performance. The enhanced cyclability of the Sn₂Fe/C nanocomposite containing Cu was attributed to both amorphization of the Sn₂Fe phase and a recombination reaction between Sn and Cu during the charging step.     

Separation of branched polystyrene by comprehensive two-dimensional liquid chromatography

Branched polystyrenes (PS) featuring a bivariate distribution in the molecular weight and in the number of branches were characterized by comprehensive two-dimensional liquid chromatography (2D-LC). The branched PS were prepared by anionic polymerization using n-butyl Li as an initiator and a subsequent linking reaction with p-(chlorodimethylsilyl)styrene (CDMSS). The n-butyl Li initiator yields polystyryl anions with broad molecular weight distribution (MWD) and the linking reaction with CDMSS yields branched PS with different number of branches. For the first dimension (1st-D) separation, reversed-phase temperature gradient interaction chromatography (RP-TGIC) was employed to separate the branched polymer according to mainly the molecular weight. In the second dimension (2nd-D) separation, the effluents from the RP-TGIC separation are subjected to liquid chromatography at chromatographic critical conditions (LCCC), in which the separation was carried out at the critical condition of linear homo-PS to separate the branched PS in terms of the number of branches. The 2D-LC resolution of RP-TGICxLCCC combination worked better than the common LCCCxsize-exclusion chromatography (SEC) configuration due to the higher resolution of RP-TGIC in molecular weight than SEC. Furthermore, by virtue of using the same eluent in RP-TGIC and LCCC (only the column temperature is different), RP-TGICxLCCC separation is free from possible 'break through' and large system peak problems. This type of 2D-LC separation could be utilized efficiently for the analysis of branched polymers with branching units distinguishable by LC separation.     

On iterations methods for zeros of accretive operators in Banach spaces

In this paper, three iterations are designed to approach zeros of set-valued accretive operators in Banach spaces. The first one is the continuous Picard type iteration involving the resolvent, the second one is the approximate Picard type iteration involving the resolvent and the third one is the Halpern type iteration involving the resolvent. Some strong convergence theorems for three iterations are proved.     

Maneuvering the surface plasmon resonance of silver nanostructures through shape-controlled synthesis

Silver nanostructures are containers for surface plasmons - the collective oscillation of conduction electrons in phase with incident light. By controlling the shape of the container, one can control the ways in which electrons oscillate, and in turn how the nanostructure scatters light, absorbs light, and enhances local electric fields. With a series of discrete dipole approximation (DDA) calculations, each of a distinctive morphology, we illustrate how shape control can tune the optical properties of silver nanostructures. Calculated predictions are validated by experimental measurements performed on nanocubes with controllable corner truncation, right bipyramids, and pentagonal nanowires. Control of nanostructure shape allows optimization of plasmon resonance for molecular detection and spectroscopy.