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Abstract: Growth of sexithiophene films on both ordered and disordered TiO2(110) surfaces has been investigated by angle-resolved ultraviolet photoemission spectroscopy, atomic force microscopy, and X-ray diffraction including grazing-incidence characterization. The order (or disorder) of the TiO2(110)-1×1 surface has been observed to profoundly influence the electronic, morphological, and structural properties of the 6T films: the band alignment, which determines the injection efficiency of contacts, has been considerably modified by 0.6eV, and a morphology with either needle-like or dendritic-like islands has been obtained. The changes in the 6T film properties are associated with the orientational modifications of sexithiophene molecules within the films, either flat-lying or upright standing, 6T(010) or 6T(100) crystallites, respectively. The growth of different crystallite orientations is argued to be controlled by the kinetics mediated by the (dis)order of the TiO2(110) surface rather than exclusively by chemical interaction between the molecule and the substrate. [Copyright &y& Elsevier]

Abstract: This work focuses on structural and morphological studies of para-sexiphenyl thin films grown on freshly cleaved KCl(100) surfaces. Atomic force microscopy images show different morphologies, namely terrace like growth and different kinds of needle like growths. By X-ray diffraction methods different crystal alignments of the organic film on the substrate are found. The different crystal alignments are assigned to the observed morphologies by transmission electron microscopy and diffraction. Regarding the incommensurate interfaces (on the part of the surface unit cells) it is concluded that the epitaxy is dominated by an alignment of small crystallites on the KCl(100) surface. [Copyright &y& Elsevier]

Abstract: In this work we use atomic force microscopy and X-ray diffraction to study morphology and growth kinetics of para-sexiphenyl layers deposited by hot wall epitaxy on crystalline KCl(001) substrates. It is shown that the growth on KCl(001) is characterized by co-existence of long needles (“laying” molecules) and terraces structured islands (“standing” molecules). The former are the initial growth stage of the films, generating a rectangular network in accordance with surface symmetry of the substrate. It is in contrast to mica substrates, where para-sexiphenyl forms only needles with one preferential direction. [Copyright &y& Elsevier]

Abstract: Itraconazole-loaded NLC for pulmonary application were developed. In Precirol ATO 5 and oleic acid Itraconazole had the highest solubility. The solid lipid and the oil were mixable in a ratio 9:1 possessing a melting point above body temperature. 0.4% Itraconazole was dissolved in this lipid blend. Eumulgin SLM 20 was the stabilizer with the highest affinity to the lipid blend used as particle matrix. 2.5% Eumulgin SLM 20 was sufficient to obtain NLC with a narrow particle size distribution and sufficient stability. The tonicity of the formulation was adjusted with glycerol. Sterility was obtained by autoclaving. Neither the addition of glycerol nor autoclaving had an influence on the particle size and the zeta potential of Itraconazole-loaded NLC. SEM images showed spherical particles confirming the particle size measured by light scattering techniques. An entrapment efficiency of 98.78% was achieved. Burst release of Itraconazole from the developed carrier system was found. Itraconazole-loaded NLC possessed good storage stability. Nebulizing Itraconazole-loaded NLC with a jet stream and an ultrasonic nebulizer had no influence on the particle size and the entrapment efficiency of Itraconazole in the particle matrix, being a precondition for pulmonary application. [Copyright &y& Elsevier]

Abstract: Quaterphenyl thin films were grown on Au(111) surfaces which were intentionally covered by different amounts of carbon. The films were investigated by X-ray diffraction and atomic force microscopy. An epitaxial character of the quaterphenyl crystallites could be confirmed for films grown on a clean Au(111) surface, with the (211) plane of quaterphenyl parallel to the Au(111) surface. It was found that the in-plane orientation of the quaterphenyl crystallites is determined by aligning the long molecular axes along and , facing the aromatic units of the molecules parallel to Au(111). Carbon coverages of 15% or 50% of the Au(111) surface cause a change in the orientation of the crystallites and a loss of the epitaxial orientation of the crystallites. In case of 15% carbon coverage the (201) plane of quaterphenyl crystallites develops parallel to Au(111), and 50% carbon coverage causes a (001) orientation of the crystallites. Both planes are cleavage planes of quaterphenyl. The film morphology consists of aligned needles for quaterphenyl films grown on the clean Au(111) surface, bent and randomly oriented needles at 15% carbon coverage and of uniformly distributed hillocks at 50% carbon coverage. The corresponding morphologies can be explained by the crystal structure features of quaterphenyl in combination with the orientation of the molecules within the thin films. [Copyright &y& Elsevier]

A thermomechanical model for an oxide-confined GaAs-based VCSEL emitter is presented. The impact of the lattice mismatch, the oxide shrinkage and the thermal stress on the mechanical reliability is evaluated. Under standard operating conditions, calculations show that the temperature increase has a negligible influence on the overall mechanical stress. The oxide shrinkage highly deforms the epitaxial structure at the edge of the optical aperture. At oxide corners, the calculated stress is beyond the experimental yield strength of GaAs micro-pillars, enabling the nucleation of the dislocations forming dark line defects. The high misfit stress in the quantum well layers can favor there the dislocation propagation. • Degradation of oxide confined VCSELs is associated with dark lines (dislocations). • The oxide formation is associated with a mechanical deformation of the structure. • Dislocations form at oxide edge and propagate toward the optical aperture. • Degradation causes further oxidation, deforming the VCSEL beyond the yield strength. • The lattice mismatch strains the quantum well, favoring the defect propagation. [ABSTRACT FROM AUTHOR]

Abstract: A para-sexiphenyl monolayer of near up-right standing molecules (nominal thickness of 30Å) is investigated in-situ by X-ray diffraction using synchrotron radiation and ex-situ by atomic force microscopy. A terrace like morphology is observed, the step height between the terraces is approximately one molecular length. The monolayer terraces, larger than 20μm in size, are extended along the [001] direction of the TiO2(110) substrate i.e. along the Ti–O rows of the reconstructed substrate surface. The structure of the monolayer and its epitaxial relationship to the substrate is determined by grazing incidence X-ray diffraction. Extremely sharp diffraction peaks reveal high crystalline order within the monolayer, which was found to have the bulk structure of sexiphenyl. The monolayer terraces are epitaxially oriented with the (001) plane parallel to the substrate surface (out-of-plane order). Four epitaxial relationships are observed. This in-plane alignment is determined by the arrangement of the terminal phenyl rings of the sexiphenyl molecules parallel to the oxygen rows of the substrate. [Copyright &y& Elsevier]