Synthesis and Photophysical Properties of 9,10-Disubstituted Anthracenes

We report the synthesis and photophysical characterization of four 9,10-disubstituted diphenylanthracenes with specific modifications of the model backbone which involve both the 9,10 para substituents at the phenyl rings and the substitution with carbon-carbon triple bonds. The effects of such modifications on the photoluminescence and electroluminescence properties have been investigated on the basis of the diphenylanthracene molecular characteristics and in view of application to light-emitting devices. We have found that the substitution with the carbon-carbon triple bonds at the two 9,10-phenyls noticeably alters the electronic states of the reference molecule, also introducing a certain degree of sensitivity to the phenyl substituents, which improves the tunability of the optical emission. Differently, the 9,10 para substituents produce minor changes in the single-molecule properties, due to the lack of electronic conjugation across the 9,10-phenyls. However, even a single nitro substituent in the phenyl para position produces the formation of excimers, which appreciably reduces the optical quantum efficiency. These properties are maintained in solid-state blends and simple spin-coated bilayer electroluminescent devices have been fabricated

Aesthetic satisfaction in lip and palate clefts: a comparative study between secondary and tertiary bone grafting

Lip and palate cleft represent one of the most frequently occurring congenital deformity, which includes dental anomalies, such as variation in tooth number and position. In case of hypodontia implant-prosthetic rehabilitation offers significant advantages in terms of function, aesthetics and quality of life and bone graft is usually needed. Secondary bone grafting, generally performed in the mixed dentition phase (years 8-11) seems to be the most successful method to allow for rehabilitation. It's often necessary to perform a tertiary bone grafting in adult age in order to achieve better bone quantity and quality before implant placement. Aim of this retrospective study was to evaluate the aesthetic perception that patients had of themselves comparing dental implants placed in tertiary grafted alveolar cleft sites with a previous secondary grafting to only secondary grafting. Between 2009 and 2012, fourteen alveolar cleft were treated with implant rehabilitation and eleven of them received tertiary bone grafting six months prior to implant placement. All patients were questioned to give a score from 1 to 10 their aesthetic satisfaction of their smile before and after implant rehabilitation and during pre-surgery provisional rehabilitation. At the end of their prosthesis rehabilitation patients who received tertiary bone grafting resulted more satisfied than those who had secondary bone grafting only (9.5 vs 8)

Suppression and Enhancement of Soliton Switching During Interaction in Periodically Twisted Birefringent Fiber

Soliton interaction in periodically twisted birefringent optical fibers has been analysed analytically with refernce to soliton switching. For this purpose we construct the exact general two-soliton solution of the associated coupled system and investigate its asymptotic behaviour. Using the results of our analytical approach we point out that the interaction can be used as a switch to suppress or to enhance soliton switching dynamics, if one injects multi-soliton as an input pulse in the periodically twisted birefringent fiber.Comment: 10 pages, 4 figures, Latex, submitted to Phys. Rev.

Impossibility of spontaneously breaking local symmetries and the sign problem

Elitzur's theorem stating the impossibility of spontaneous breaking of local symmetries in a gauge theory is reexamined. The existing proofs of this theorem rely on gauge invariance as well as positivity of the weight in the Euclidean partition function. We examine the validity of Elitzur's theorem in gauge theories for which the Euclidean measure of the partition function is not positive definite. We find that Elitzur's theorem does not follow from gauge invariance alone. We formulate a general criterion under which spontaneous breaking of local symmetries in a gauge theory is excluded. Finally we illustrate the results in an exactly solvable two dimensional abelian gauge theory.Comment: Latex 6 page

Stacked optical antennas for plasmon propagation in a 5 nm-confined cavity

The sub-wavelength concentration and propagation of electromagnetic energy are two complementary aspects of plasmonics that are not necessarily co-present in a single nanosystem. Here we exploit the strong nanofocusing properties of stacked optical antennas in order to highly concentrate the electromagnetic energy into a 5 nm metal-insulator-metal (MIM) cavity and convert free radiation into guided modes. The proposed nano-architecture combines the concentration properties of optical nanoantennas with the propagation capability of MIM systems, paving the way to highly miniaturized on-chip plasmonic waveguiding

Design, fabrication, and characterization of deep-etched waveguide gratings

One-dimensional (1-D) deep-etched gratings on a specially grown AlGaAs wafer were designed and fabricated. The gratings were fabricated using state-of-the-art electron beam lithography and high-aspect-ratio reactive ion etching (RIE) in order to achieve the required narrow deep air slots with good accuracy and reproducibility. Since remarkable etch depths (up to 1.5 /spl mu/m), which completely cut through the waveguide core layer, have been attained, gratings composed of only five periods (and, thus, shorter than 6 /spl mu/m) have a bandgap larger than 100 nm. A defect was introduced by increasing the width of the central semiconductor tooth to create microcavities that exhibit a narrow transmission peak (less than 7 nm) around the wavelength of 1530 nm. The transmission spectra between 1460 and 1580 nm have been systematically measured, and the losses have been estimated for a set of gratings, both with and without a defect, for different periods and air slot dimensions. Numerical results obtained via a bidirectional beam propagation code allowed the evaluation of transmissivity, reflectivity, and diffraction losses. By comparing experimental results with the authors' numerical findings, a clear picture of the role of the grating's geometric parameters in determining its spectral features and diffractive losses is illustrated

Persistent systemic microbial translocation, inflammation, and intestinal damage during Clostridioides difficile infection

Background. Clostridioides difficile infection (CDI) might be complicated by the development of nosocomial bloodstream infection (n-BSI). Based on the hypothesis that alteration of the normal gut integrity is present during CDI, we evaluated markers of microbial translocation, inflammation, and intestinal damage in patients with CDI. Methods. Patients with documented CDI were enrolled in the study. For each subject, plasma samples were collected at T0 and T1 (before and after CDI therapy, respectively), and the following markers were evaluated: lipopolysaccharide-binding protein (LPB), EndoCab IgM, interleukin-6, intestinal fatty acid binding protein (I-FABP). Samples from nonhospitalized healthy controls were also included. The study population was divided into BSI+/BSI- and fecal microbiota transplantation (FMT) +/FMT- groups, according to the development of n-BSI and the receipt of FMT, respectively. Results. Overall, 45 subjects were included; 8 (17.7%) developed primary n-BSI. Markers of microbial translocation and intestinal damage significantly decreased between T0 and T1, however, without reaching values similar to controls (P < .0001). Compared with BSI-, a persistent high level of microbial translocation in the BSI+ group was observed. In the FMT+ group, markers of microbial translocation and inflammation at T1 tended to reach control values. Conclusions. CDI is associated with high levels of microbial translocation, inflammation, and intestinal damage, which are still present at clinical resolution of CDI. The role of residual mucosal perturbation and persistence of intestinal cell damage in the development of n-BSI following CDI, as well as the possible effect of FMT in the restoration of mucosal integrity, should be further investigated

A Next-to-Leading-Order Study of Dihadron Production

The production of pairs of hadrons in hadronic collisions is studied using a next-to-leading-order Monte Carlo program based on the phase space slicing technique. Up-to-date fragmentation functions based on fits to LEP data are employed, together with several versions of current parton distribution functions. Good agreement is found with data for the dihadron mass distribution. A comparison is also made with data for the dihadron angular distribution. The scale dependence of the predictions and the dependence on the choices made for the fragmentation and parton distribution functions are also presented. The good agreement between theory and experiment is contrasted to the case for single $\pi^0$ production where significant deviations between theory and experiment have been observed.Comment: 22 pages, 15 figures; 3 references added, one figure modified for clarit

Unitarity Bounds for Gauged Axionic Interactions and the Green-Schwarz Mechanism

We analyze the effective actions of anomalous models in which a four-dimensional version of the Green-Schwarz mechanism is invoked for the cancellation of the anomalies, and we compare it with those models in which gauge invariance is restored by the presence of a Wess-Zumino term. Some issues concerning an apparent violation of unitarity of the mechanism, which requires Dolgov-Zakharov poles, are carefully examined, using a class of amplitudes studied in the past by Bouchiat-Iliopoulos-Meyer (BIM), and elaborating on previous studies. In the Wess-Zumino case we determine explicitly the unitarity bound using a realistic model of intersecting branes (the Madrid model) by studying the corresponding BIM amplitudes. This is shown to depend significantly on the St\"uckelberg mass and on the coupling of the extra anomalous gauge bosons and allows one to identify Standard-Model-like regions (which are anomaly-free) from regions where the growth of certain amplitudes is dominated by the anomaly, separated by an inflection point which could be studied at the LHC. The bound can even be around 5-10 TeV's for a $Z'$ mass around 1 TeV and varies sensitively with the anomalous coupling. The results for the WZ case are quite general and apply to all the models in which an axion-like interaction is introduced as a generalization of the Peccei-Quinn mechanism, with a gauged axion.Comment: 50 pages, 28 figure