Fluctuation-Induced Conductivity of Polycrystalline (Ho–Ce)Ba2Cu3O$_{7-boldsymboldelta}$ Superconductor

We report on systematic conductivity fluctuation measurements on samples of Ho_1 − x Ce _x Ba₂Cu₃O_7 − δ with x = 0.00, 0.05, and 0.10. The samples were produced by a standard solid-state reaction method, and the microstructure was analyzed by X-ray diffraction. To identify power-law divergences of the conductivity, the results were analyzed in terms of the temperature derivative of the resistivity dρ/dT and with the logarithmic derivative of the conductivity with respect to temperature − dln (Δσ)/dT. It was observed that the critical temperature decreases and that the transition width increases with increasing Ce doping. The data showed the occurrence of a two-stage transition besides the pairing transition splitting, associated with Ce doping and related with the occurrence of a phase separation. Above the critical temperature, the Gaussian and critical regimes were observed. On approaching the zero resistance state, our results showed a power-law behavior that corresponds to a phase transition from a paracoherent to a coherent state of the granular array.     

Development and validation of an HPLC/MS/MS method for the determination of sufentanil and morphine in human plasma

A sensitive and fast HPLC/MS/MS method for measurement of sufentanil and morphine in plasma was developed and validated. A single liquid-liquid extraction in alkaline medium was used for the cleanup of plasma, and fentanyl was added as an internal standard (IS). The analyses were carried out using a C18 column and the mobile phase acetonitrile-5 mM ammonium acetate + 0.25% formic acid (70 + 30, v/v). The triple-quadrupole mass spectrometer equipped with an electrospray source in positive mode was set up in the selective reaction monitoring mode to detect precursor --> product ion transition 387.0 > 238.0, 285.7 > 165.1, and 337.0 > 188.0 for sufentanil, morphine, and IS, respectively. The method was linear in the 0.05 (LOQ) - 500 ng/mL range for sufentanil and 10 (LOQ) - 1000 ng/mL range for morphine. Good selectivity, linearity, precision, accuracy, and robustness were obtained for the HPLC/MS/MS method. The proposed method was successfully applied for the determination of sufentanil and morphine in patients undergoing cardiac surgery.     

Synthesis routes for the growth of complex nanostructures

The interest in research on inorganic colloidal nanoparticles has moved to more complex structures, such as anisotropically shaped particles and branched objects. Recently, schemes for the synthesis of heterostructures have also been presented. In this article we discuss the synthesis conditions for spherical and branched nanoparticles. The influence of parameters as temperature and composition of the mixture of surfactants on the shape of the growing particles is discussed. Also, an overview on different approaches for the formation of heterostructures is presented briefly.     

Selection of excipients for the development of carvedilol loaded lipid-based drug delivery systems

Journal of Thermal Analysis and Calorimetry - Carvedilol (CARV) is a widely used drug, which has shown low oral bioavailability. Lipid-based drug delivery systems (LBDDS) appear as promising...     

Preformulation studies to guide the development of raloxifene lipid-based delivery systems

Journal of Thermal Analysis and Calorimetry - The composition and temperature dependence of viscosity and configuration entropy of glasses with chemical composition close to that used for CHROMPIC...     

Two useful identities involving spherical harmonics

We present two identities that permit a simplification of some lengthy derivations with spherical harmonics. Examples of their use are given.     

FT-IR determinations in charge-transfer interactions between phenylhydrazones and organic acceptors

Unhindered phenylhydrazones form charge-transfer complexes with organic acceptors like tetracyanoethylene and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone. FT-IR determinations on starting hydrazones allow to predict the possibility of suitable molecular associations.     

Implementation of Good Laboratory Practices (NIT-DICLA-035, Inmetro) in a technological platforms network: the Fiocruz experience

The technological platforms network (TPN) of the Oswaldo Cruz Foundation was developed as the result of the need to provide technical and scientific services to the Brazilian public health and health research networks through the use of high cost, state-of-the-art, multiuser equipment. In order to improve the quality of the services offered, a quality management system (QMS) was implemented in a group of subunits of the TPN. To achieve the planned objectives, a review of all the existing guidelines was carried out first, which led to the choice of a Brazilian guideline: Inmetro NIT-DICLA-035, ??Good Laboratory Practices?? (GLP). The next steps were the choice of the platform subunits (Pilot Project), the drafting of relevant documentation, and the creation of a quality assurance structure as well as other activities. It was clear that a proper interpretation and understanding of GLP in these platforms could make a difference in the efficacy and effectiveness of the system defined. The expertise gained through the implementation of QMS in the Pilot Project has enabled GLP implementation in the other TPN subunit platforms.     

Diffraction theory applied to X‐ray imaging with clessidra prism array lenses

Clessidra (hourglass) lenses, i.e. two large prisms each composed of smaller identical prisms or prism‐like objects, can focus X‐rays. As these lenses have a periodic structure perpendicular to the incident radiation, they will diffract the beam like a diffraction grating. Refraction in the prisms is responsible for blazing, i.e. for the concentration of the diffracted intensity into only a few diffraction peaks. It is found that the diffraction of coherent radiation in clessidra lenses needs to be treated in the Fresnel, or near‐field, regime. Here, diffraction theory is applied appropriately to the clessidra structure in order to show that blazing in a perfect structure with partly curved prisms can indeed concentrate the diffracted intensity into only one peak. When the lens is entirely composed of identical perfect prisms, small secondary peaks are found. Nevertheless, the loss in intensity in the central peak will not lead to any significant widening of this peak. Clessidras with perfect prisms illuminated by full coherent X‐ray radiation can then provide spatial resolutions, which are consistent with the increased aperture, and which are far below the height of the single small prisms.