In reply to the letter to the editor regarding "Palisade cartilage tympanoplasty compared to one-piece composite cartilage-perichondrium grafts for transcanal endoscopic treatment of subtotal tympanic membrane perforations: a retrospective study".

This is a reply letter to the manuscript "The size and diameter of pieces of cartilage are not fixed for the palisade technique and one-piece technique", regarding the elevation of a tympanomeatal flap and keratin pearl formation in "Palisade cartilage tympanoplasty compared to one-piece composite cartilage-perichondrium grafts for transcanal endoscopic treatment of subtotal tympanic membrane perforations: a retrospective study" ( https://doi.org/10.1007/s00405-020-05947-3 ).

(67)Ga and (68)Ga purification studies: preliminary results.

The positron emission tomography technique is very useful for diagnosis of several diseases. (68)Ga is a positron emitter with half-life of 67.7 min. As it is available from (68)Ge/(68)Ga generator systems, it is not necessary to have a nearby cyclotron. However, the eluate from commercial generators contains high levels of metallic impurities, which compete with (68)Ga in biomolecular labeling. Thus, a subsequent purification step is needed after generator elution. Here we present the results of two different methods developed for handmade purification of (68)Ga and (67)Ga for subsequent radiolabeling of biomolecules. Two purification methods were employed. The first one uses a cation exchange resin, and (68)Ga is eluted with a solution of acetone/acid. The second method of purification is performed by column chromatography solvent extraction, with (68)Ga recovery in deionized water. The best result was achieved with cationic resin AG50W-X8 (>400 mesh). However, the resin is not commercially available. The extraction chromatography column based on absorption of diisopropyl ether in XAD-16 is the most promising purification method. Although the levels of (68)Ga recovery and purification were smaller with the cationic resin method, its advantage is the (68)Ga recovery in deionized water.

Technetium-99m -- new production and processing strategies to provide adequate levels for SPECT imaging.

The most important radioisotope for use in Nuclear Medicine is (99m)Tc, supplied in the form of a (99)Mo/(99m)Tc generator. After the supply crisis of (99)Mo starting in 2008 the availability of (99)Mo became a worldwide concern. The purpose of this work is to do a brief story of the availability of (99)Mo in the world followed by an overview of the production routes of (99)Mo and the generators technology.

Photoluminescence spectroscopy of pure pentacene, perfluoropentacene, and mixed thin films.

We report detailed temperature dependent photoluminescence (PL) spectra of pentacene (PEN), perfluoropentacene (PFP), and PEN:PFP mixed thin films grown on SiO(2). PEN and PFP are particularly suitable for this study, since they are structurally compatible for good intermixing and form a model donor/acceptor system. The PL spectra of PEN are discussed in the context of existing literature and compared to the new findings for PFP. We analyze the optical transitions observed in the spectra of PEN and PFP using time-dependent density functional theory calculations. Importantly, for the mixed PEN:PFP film we observe an optical transition in PL at 1.4 eV providing evidence for coupling effects in the blend. We discuss a possible charge-transfer (CT) and provide a tentative scheme of the optical transitions in the blended films.

Retrieving the spatial distribution of cavity modes in dielectric resonators by near-field imaging and electrodynamics simulations.

For good performance of photonic devices whose working principle is based on the enhancement of electromagnetic fields obtained by confining light into dielectric resonators with dimensions in the nanometre length scale, a detailed knowledge of the optical mode structure becomes essential. However, this information is usually lacking and can only be indirectly obtained by conventional spectroscopic techniques. Here we unraveled the influence of wire size, incident wavelength, degree of polarization and the presence of a substrate on the optical near fields generated by cavity modes of individual hexagonal ZnO nanowires by combining scanning near-field optical microscopy (SNOM) with electrodynamics calculations within the discrete dipole approximation (DDA). The near-field patterns obtained with very high spatial resolution, better than 50 nm, exhibit striking size and spatial-dispersion effects, which are well accounted for within DDA, using a wavevector-dependent dipolar interaction and considering the dielectric anisotropy of ZnO. Our results show that both SNOM and DDA simulations are powerful tools for the design of optoelectronic devices able to manipulate light at the nanoscale.

Direct imaging of the visible emission bands from individual ZnO nanowires by near-field optical spectroscopy.

Room-temperature photoluminescence (PL) measurements have been performed on single-crystal ZnO nanowires grown on SiO2/Si and quartz substrates by the vapor transport method using Au as a catalyst. Two emission bands are apparent, one in the UV spectral region around 380 nm (3.26 eV) associated with exciton recombination processes and a much broader structure in the visible range from 420 to 700 nm, which exhibits two distinct peak-like features around 520 and 590 nm (2.38 and 2.10 eV). Spectrally resolved scanning near-field optical microscopy (SNOM) of single ZnO nanowires have been performed for a direct imaging of the PL emission with spatial resolution below 100 nm. SNOM results provide evidence that the yellow emission band observed at 590 nm is a unique property of the ZnO nanowires, being most likely related to radiative recombination processes associated with Au impurities introduced during the catalytic growth.

Thickness-dependent structural transitions in fluorinated copper-phthalocyanine (F16CuPc) films.

The detailed structure of F16CuPc films on SiO2 has been determined by means of in situ grazing incidence X-ray diffraction from the first monolayer to thicker films. In contrast to films of the homologous H16CuPc molecule, the F16CuPc films exhibit the same structure independently from the deposition temperature. The films show a thickness-dependent polymorphism manifested in the in-plane crystal structure, which implies large differences in the molecular tilt within the cofacial stacking of the molecules.

In situ study of the growth of nanodots in organic heteroepitaxy.

We report the self-organization of organic nanodots with high crystallinity during the growth of organic heterostructures of Di-indenoperylene (DIP) onto copper-hexadecafluorophthalocyanine (F16CuPc), donor and acceptor molecules, respectively. The process is related to the Stranski-Krastanov growth mode, which is accompanied by a novel type of structural reconstruction of the underlying organic film. This reconstruction affects three monolayers adjacent to the organic interface. In spite of the close resemblance to the formation of semiconductor nanostructures for inorganic heteroepitaxy, the present results conclusively demonstrate a distinctly different growth mechanism for organic heteroepitaxy whose understanding demands further theoretical studies.

Structural rearrangements during the initial growth stages of organic thin films of F16CuPc on SiO2.

We present an experimental study on the first stages of the thin film growth of the organic molecule F(16)CuPc (hexadecafluoro-copper-phthalocyanines) on SiO(2). By means of in situ X-ray reflectivity, in situ grazing incidence X-ray diffraction (GIXD), and ex situ atomic force microscopy (AFM), we provide a detailed picture of the film growth mode and its structural evolution at the nanometer scale. We discovered the formation of a low-density layer of molecular aggregates with heights between 5 and 10 A at the interface with the SiO(2) and show that, on top of this interfacial layer, the nucleation and two-dimensional growth of elongated islands of upright standing molecules take place. Structural changes are observed, pointing to significant relaxations of the lattice parameters within the first layers of standing molecules.

Influence of Si interdiffusion on carbon-induced growth of Ge quantum dots: a strategy for tuning island density.

We have studied the epitaxial growth of self-assembled Ge quantum dots when a submonolayer of carbon is deposited on a Ge wetting layer (WL) prior to the growth of the dots. Using atomic-force microscopy combined with optical techniques like Raman and ellipsometry, we performed a systematic study of the role played by thermally activated Si interdiffusion on dot density, composition and morphology, by changing only the growth temperature T(WL) of the WL. Strikingly, we observe that higher dot densities and a narrower size distribution are achieved by increasing the deposition temperature T(WL), i.e. by enhancing Si interdiffusion from the substrate. We suggest a two-stage growth procedure for fine tuning of dot topography (density, shape and size) useful for possible optoelectronic applications.