Type I collagen-mediated synthesis of noble metallic nanoparticles networks and the applications in Surface-Enhanced Raman Scattering and electrochemistry

In this paper, we demonstrated an effective enviromentally friendly synthesis route to prepare noble metallic (Au, Ag, Pt and Pd) nanoparticles (NPs) networks mediated by type I collagen in the absence of any seeds or surfactants. In the reactions, type I collagen served as stabilizing agent and assembly template for the synthesized metallic NPs. The hydrophobic interaction between collagen and mica interface as well as the hydrogen bonds between inter- and intra-collagen molecules play important roles in the formation of collagen-metallic NPs networks. The noble metallic NPs networks have many advantages in the applications of Surface-Enhanced Raman Scattering (SERS) and electrochemistry detection. Typically, the as-prepared Ag NPs networks reveal great Raman enhancement activity for 4-ATP, and can even be used to detect low concentration of DNA base, adenine.

Half metallic properties of Sr2CuOsO6

The half metallic properties of the recent synthesized Sr2CuOsO6 were predicted by using the density functional theory. The effects of electron correlation and spin-orbit coupling (SOC) were studied. The calculations show that without considering SOC effect, Sr2CuOsO6 is half metallic and ferrimagnetic. By including both electron correlation and spin-orbit coupling, the total spin magnetic moment is 0.89 mu(B), total orbital moment 0.43 mu(B) in opposite direction, making the net magnetic moment 0.46 mu(B). SOC ruins the half metallic character. Crown Copyright (C) 2009 Published by Elsevier B. V. All rights reserved.

Luminescent and Mesoporous Europium-Doped Bioactive Glasses (MBG) as a Drug Carrier

Luminescent and mesoporous europium-doped bioactive glasses (MBG:Eu) were successfully synthesized by a two-step acid-catalyzed self-assembly process combined with hydrothermal treatment in an inorganic-organic system. The obtained MBG was performed as a drug delivery carrier to investigate the drug storage/release properties using ibuprofen (IBU) as a model drug. The structural, morphological, textural and optical properties were well characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N-2 adsorption/desorption, and photoluminescence (PL) spectra, respectively. The results reveal that the MBG exhibit the typical ordered characteristics of the hexagonal mesostructure. This composite shows sustained release profile with ibuprofen as the model drug. The IBU-loaded samples still show red luminescence of Eu3+ (D-5(0)-F-7(1, 2)) under UV irradiation, and the emission intensities of Eu3+ in the drug carrier system vary with the released amount of IBU, thus making the drug release be easily tracked and monitored by the change of the luminescence intensity.

Ferrimagnetic and half-metallic CaCu3Fe4O12: Prediction from first principles investigation

The structural stability and physical properties of CaCu3Fe4O12 were studied by the use of the full-potential linearized augmented plane wave method. The authors' calculated result indicates that the title compound is stable both thermodynamically and mechanically. It is ferrimagnetic and half-metallic. The calculated magnetic structure reveals that the coupling of Cu-Fe is antiferromagnetic, while those of Cu-Cu and Fe-Fe are ferromagnetic.

Long lasting phosphorescence of Eu2+ in reduced SrO-B2O3 glasses

The blue long-lasting phosphorescence (LLP) phenomenon was observed for Eu2+-doped SrO-B2O3 glasses prepared in the reducing atmosphere. The phosphorescence peaks at about 450 nm due to the 4f5d -> 4f transition of Eu2+. With the doping of different amounts of Eu2+, the concentration-quenching phenomenon was observed for both the LLP and photoluminescence of the glasses, and the critical concentration for the two cases was same, i.e., 0.02 mol% Eu2+. And by the investigation of the TL curves, the content of Eu2+ had an effect on the trap depth of the samples. At last the possible mechanism of the LLP of the samples was suggested.

Long lasting phosphorescence in Eu3+ and Ce3+ co-doped strontium borate glasses

Long lasting phosphorescence (LLP) was observed in Eu2+, Ce3+ co-doped strontium borate glasses prepared under the reducing atmosphere due to the emission of both Eu2+ and Ce3+. The methods of photoluminescence, thermoluminescence and phosphorescence were used to study the samples, and possible mechanism was suggested. The co-doping of Ce3+ ions poisoned the phosphorescence emission of Eu2+ because of the competition to obtain the trapped electron. The phosphorescence of Ce3+ in the sample decays more quickly than that of Eu2+, which is suggested for the reason that the emission energy of Ce3+ is higher or the distance between Ce3+ and electron traps of the glasses is longer.

Near infrared long lasting emission of Yb3+ and its influence on the optical storage ability of Mn2+-activated zinc borosilicate glasses

The near infrared long lasting phosphorescence of Yb3+ is observed in Yb3+ and Mn2+ codoped zinc borosilicate glasses. Compared with the glasses solely activated by Mn2+, when the Yb3+ ion is codoped, the red long lasting phosphorescence of the samples is largely improved in both brightness and persistent time but the photostimulated long lasting phosphorescence is greatly depressed. It is considered that the appearance of the phosphorescence of Yb3+ is due to the alteration of the energy transfer channel; additionally, Yb3+ also changes the trap depth of the glasses with the shallower trap predominating therefrom the red long lasting phosphorescence is improved and the photostimulated long lasting phosphorescence is degraded.

Effect of samarium on Mn activated zinc borosilicate storage glasses

Samarium and manganese co-doped zinc borosilicate storage glasses were prepared by high temperature solid state method. The effect of doping samarium on the defect of Mn activated sample was studied by means of thermoluminescence spectra. It was found that the shallower traps of the sample predominate with the addition of samarium, as a result, the phosphorescence and storage properties of the manganese doped zinc borosilicate glasses were greatly changed.

Aggregation-based fabrication and assembly of roughened composite metallic nanoshells: Application in surface-enhanced Raman scattering

This paper reports an aggregation-based method for the fabrication of composite Au/Ag nanoshells with tunable thickness and surface roughness. It is found that the resultant roughened composite Au/Ag nanoshells can attract each other spontaneously to form films at the air-water interface. Importantly, such films can be transferred onto the solid substrates without being destroyed and show excellent surface-enhanced Raman scattering (SERS) enhancement ability. Their strong enhancement ability may stem from the unique two-dimensional structure itself.

Hydrogen peroxide biosensor based on sol-gel-derived glasses doped with Eastman AQ polymer

A hydrogen peroxide biosensor based on sol-gel-derived glasses doped with poly(ester sulfonic acid) Eastman AQ 55D was constructed. Thionine (TH), as a mediator, was incorporated in this matrix by electrostatic force between TH+ and the negatively charged sulfonic acid group in Eastman AQ polymer. Performance and characteristics of the sensor were evaluated with respect to response time, sensitivity and storage stability. The enzyme electrode has a sensitivity of 11.36 muA mM(-1) with a detection limit of 5.0 x 10(-7) M H2O2, and the sensor achieved 95% of the steady state current within 20 s. (C) 2001 Elsevier Science B.V. All rights reserved.

Roles of oxygen vacancy and lower valence metallic ion in direct decomposition of NO over La-2-x(Sr,Th)(x)CuO4+/-lambda

Two systems of La2-xSrxCuO4+/-lambda and La2-xThxCuO4+/-lambda, mixed oxides with K2NiF4 structure were synthesized. The compositions and structures of the catalysts were characterized by means of XRD, XPS, chemical analysis and so on. The catalytic behavior for the direct decomposition of NO has been investigated. The results show that the catalytic activity is closely related to the oxygen vacancy and lower valence metallic ion in the direct decomposition of NO. The presence of oxygen vacancy is necessary for mixed oxide to have steady activity in NO decomposition.

Metallic foam processing from the liquid state

Cox, S.J., Bradley, G. and Weaire, D. (2001) Metallic foam processing from the liquid state: the competition between solidification and drainage. Eur. Phys. J. AP 14:87-97. Sponsorship: This research was supported by the Prodex programme of ESA, and is a contribution to ESA contract C14308/AO-075-99. SJC was supported by Enterprise Ireland and a Marie Curie fellowship. GB was supported by the HPC Programme of TCD.

Coordination changes in magnesium silicate glasses

Wilding, Martin; Benmore, C.J.; Tangeman, J.A.; Sampath, S., (2004) 'Coordination changes in magnesium silicate glasses', Europhysics Letters 67 pp.212-218 RAE2008

Inorganic glasses, glass-forming liquids and amorphizing solids

Greaves, George; Sen, S., (2007) 'Inorganic glasses, glass-forming liquids and amorphizing solids', Advances in Physics 56(1) pp.1-166 RAE2008

Structure of glasses and melts

Wilding, M. C., Benmore, C. J. (2006). Structure and Glasses and Melts. reviews in Mineralogy and Geochemistry, 63 (1), 275-311 RAE2008