Electrochemical modification of Bi2S3 coatings in a nickel plating electrolyte

The electrochemical behavior of Bi₂S₃ coatings in Watts nickel plating electrolyte was investigated using the cyclic voltammetry, electrochemical quartz crystal microbalance, X-ray diffraction, and energy dispersive X-ray analysis methods. During the bismuth sulfide coating reduction in Watts background electrolyte in the potential region from −0.4 to −0.6 V, the Bi₂S₃ and Bi(III) oxygen compounds are reduced to metallic Bi, and the decrease in coating mass is related to the transfer of S²⁻ ions from the electrode surface. When the bismuth sulfide coating is reduced in Watts nickel plating electrolyte, the observed increase in coating mass in the potential region −0.1 to −0.4 V is conditioned by Ni²⁺ ions reduction before the bulk deposition of Ni, initiated by Bi₂S₃. In this potential region, the reduction of Bi(III) oxygen compounds can occur. After the treatment of as-deposited bismuth sulfide coating in nickel plating electrolyte at E = −0.3 V, the sheet resistance of the layer decreases from 10¹³ to 500–700 Ω cm. A metal-rich mixed sulfide Ni₃Bi₂S₂–parkerite is obtained when as-deposited bismuth sulfide coating is treated in Watts nickel plating electrolyte at a potential close to the equilibrium potential of the Ni/Ni²⁺ system and then annealed at temperatures higher than 120 °C.     

Synthesis and bioactive properties of macroporous nanoscale SiO2–CaO–P2O5 bioactive glass

A macroporous nanoscale bulk bioactive glass (SiO₂–CaO–P₂O₅ system) was prepared by sol–gel co-template method. Porosimeter analysis showed that the as-synthesized bioactive glasses (BGs) had a porosity of 85% and exhibited a multimodal pore size distribution, nanopores (10–40 nm) and macropores (100 nm–10 μm). Morphological and structural characterizations showed the pores were interconnected with pore walls of about 250 nm in width and 1 μm in length. In vitro bioactivity test indicated that the as-synthesized bulk BGs exhibited faster apatite layer formation capability than the conventional sol–gel BGs. Additionally, the deposited layer was identified as hydroxycarbonate apatite, which is similar to the inorganic part of human bone.     

Preparation and characterization of the sol-gel nano-bioactive glasses modified by the coupling agent gamma-aminopropyltriethoxysilane

The sol-gel derived bioactive glasses (SBG) have been used in bone-tissue engineering because of their excellent biocompatibility and osteoconductivity. In this study, nano-SBG was successfully achieved through a wet mechanical grinding technique, and to further improve its dispersibility and cells proliferation, a silane coupling agent was coupled onto the surface of nano-SBG. Gamma-aminopropyltriethoxysilane (APTES) was used to the surface modification of the nano-SBG (60 mol%SiO₂, 36 mol%CaO, 4 mol%P₂O₅) by a wet-chemical method in a dynamic inert nitrogen atmosphere. The surface properties of the biomaterials before and after modification were characterized and compared using FTIR and XPS. The characteristic peaks in FTIR spectra indicated that -CH₂CH₃ and -NH₂ groups appeared on the surface of modified nano-SBG, and also, XPS spectra analysis revealed that nitrogen element was detected and carbon concentration increased on the surface of nano-SBG after modification. The above analysis proved that the desired groups of APTES had been covalently bonded onto the surface of nano-SBG.     

Full-range, complex spatial light modulator for real-time holography

We demonstrate a full-range complex and transmissive spatial light modulator (SLM) for simultaneous and independent amplitude and phase modulation of an input wave field. Arbitrary scalar complex optical fields are generated by stacking a pixelated liquid crystal display operating in phase-only (2π) modulation with passive polarization-sensitive components. The principle is based on optical combining the light fields of two neighboring phase-only modulating pixels, which were made orthogonally polarized by a structured half-wave plate, then passing through a birefringent plate to laterally shift one of the beams collinear to the other, and finally bringing to interference by a linear polarizer. Complex modulation by the proposed SLM is experimentally verified in monochrome green operation.     

Ferroelectric phase transition in SbSI type crystals

In this work Lorenz field coefficients F for SbSI type crystals are estimated. Also transverse and longitudinal frequencies (ω _T and ω _l) of optical vibrations are determined. From a study of these quantities it was concluded that a combination of F is an inadequate condition for ferroelectric phase transitions to take place. Taking the electronic structure, chemical bond model, electronic potential and condition ω _T—>0 into account, the phase transition in SbSI type crystals was investigated. The dependence of the electronic potential upon the composition of V-VI-VII crystals and mixed crystals has revealed the factors that change the phase transition temperature T _c and the dynamics of the soft mode.     

Multiplexed recording based on the reference wave correlation for computer-generated holographic data storage

Optical Review - Holographic data storage (HDS) based on a computer-generated hologram (CGH) technique has been proposed as a promising approach to realize an in-line and simple HDS system. This...     

Morphological control and in vitro bioactivity of nanoscale bioactive glasses

In this study, nanoscale bioactive glasses with different morphologies were prepared through sol-gel process using lactic acid as hydrolysis promoter. The effect of lactic acid concentration on the morphology of bioactive glass was characterized. The influence of the morphology on the in vitro bioactivity of samples was investigated in simulated body fluid and examined by various methods. The results showed that nanoscale surface morphologies with high roughness, created by addition of lactic acid, greatly enhanced the in vitro bioactivity of as-prepared samples. It was found that the morphology with nanoscale surface feature and pore size distribution, in addition to specific surface area and pore volume, plays an important role in accelerating the formation of carbonated hydroxyapatite. According to our results, bioactive glasses possessing surface morphology with significant numbers of nanoscale bioactive glass particles and a narrow unimodal or bimodal mesopore structure, exhibit the best in vitro bioactivity.     

Investigation of the electronic structure of the SbSeBr cluster

The energy levels of valence bands (VB) in SbSeBr crystals were calculated for investigation of the photoelectron emission spectra of A⁵B⁶C⁷ — type crystals. The molecular model of this crystal was used for calculation of VB by the Density Functional Theory (DFT) and Unrestricted Hartree — Fock (UHF) methods. The molecular cluster consisting of 20 molecules of SbSeBr was used for calculations of averaged total density of states including atom vibrations. The spectra of averaged total density of states from VB in the SbSeBr cluster were compared with experimental photoelectron emission spectra from VB of A⁵B⁶C⁷ — type crystals. The results of comparison clarify that the atomic vibrations are one of possible reasons for the smoother appearance of the experimental X-ray photoelectron spectrum (XPS).      

Acetic acid derived mesoporous bioactive glasses with an enhanced in vitro bioactivity

In this paper, a novel mesoporous bioactive glass (MBG) with a nanoscale surface feature in the SiO₂–CaO–P₂O₅ system has been synthesized by means of the acetic acid-assisted sol–gel process. As a comparison, the normal sol–gel derived bioactive glass (NBG) with the same composition was also synthesized. The structure and in vitro bioactivity of as-prepared samples were characterized using various methods. The results indicated that using acetic acid as a structure-assisted agent and hydrolysis catalyst is in favor of preparing the bioactive glass with nanoscale surface morphology, larger specific surface area, relatively homogeneous sized mesopore distribution. Depending on this novel structure, MBG presented an enhanced formation of hydroxyl-carbonate apatite layer and high in vitro bioactivity.