The Island CGH, a new coding scheme: concept and demonstration.

Computer generated holograms (CGHs) are powerful optical elements used in many fields, such as wavefront shaping, quality testing of complex optics, and anti-counterfeiting devices. The Lee algorithm is the most used to generate binary amplitude Fourier holograms. Grayscale CGHs are known to give a higher reconstruction quality than binary holograms, but they usually require a cumbersome production process. A very simple and straightforward method of manufacturing rewritable grayscale CGHs is proposed here by taking advantage of two key components: a digital micro-mirror device (DMDs) and a photochromic plate. An innovative algorithm, named Island algorithm, able to generate grayscale amplitude Fourier CGHs, is reported and compared with the standard Lee approach, based on 9 levels. A crucial advantage lies on the fact that the increase or decrease of the quantification does not affect the spatial resolution. In other words, the new coding leads to a higher spatial resolution (for a given CGH size) and a reconstructed image with an order of magnitude higher contrast with respect to the classical Lee-coded hologram. In order to show the huge potential of our approach, a 201 level Island hologram is designed, produced and reconstructed, pushing the contrast to values higher than104. These results reveal the potential of our process as well as our algorithm for generating programmable grayscale CGHs.

Programmable CGH on photochromic plates coded with DMD generated masks.

Computer Generated Holograms (CGHs) are used for wavefront shaping and complex optics testing. Present technology allows for recording binary CGHs. We propose a Digital Micro-mirror Device (DMD) as a reconfigurable mask, to record rewritable binary and grayscale CGHs on a photochromic plate. Opaque at rest, this plate becomes transparent when it is illuminated with visible light of suitable wavelength. We have successfully recorded the very first amplitude grayscale CGH, with a contrast greater than 50, which was reconstructed with a high fidelity in shape, intensity, size and location. These results reveal the high potential of this method for generating programmable/rewritable grayscale CGHs, which combine DMDs and photochromic substrates.

Metal-enhanced Förster resonance energy transfer (ME-FRET) in anthracene/tetracene-doped crystal systems.

Anthracene tetracene-doped crystals (TA) dispersed in a thin polymer film matrix have been reported as efficient down converting systems based on Förster Resonance Energy Transfer (FRET) which occurs efficiently from donor (anthracene) to acceptor (tetracene) molecules. In this work, we demonstrate that the efficiency of this system can be further improved by a metal-enhanced FRET, which is obtained by incorporating metal nanoparticles into the polymer matrix. We report on the preparation and optical responses of polymeric transparent thin films where dodecanethiol-capped silver or gold nanoparticles are dispersed with TA in a polymethylmethacrylate (PMMA) matrix. A maximum of 11-fold and 6.5-fold enhancement was achieved with silver and gold nanoparticles, respectively. Efficiency is discussed in terms of film morphology and plasmon resonance induced effects.

Outside rules inside: the role of electron-active substituents in thiophene-based heterophenoquinones.

The biradicaloid vs. quinoidal character of the ground state of thiophene-based heterophenoquinones bearing donor or acceptor groups is investigated. Keeping the conjugation length fixed, namely, the 5,5'-bis(3,5-di-tert-butyl-4-oxo-2,5-cyclohexadiene-1-ylidene)-2,2'-dihydroxy bithiophene backbone, an opposite effect occurs depending on the donating or withdrawing nature of the substituents. The character of the ground state depends not only on the electronic nature of the substituents but also on their position on the molecular skeleton: donor groups on the 3,3'-positions of the bithiophene central core stabilize a quinoidal ground state, whereas a biradicaloid electronic structure results from the introduction of the same donor groups onto the lateral phenones. Withdrawing groups behave similar to donors, but in the opposite direction.

Light-triggered cardiac microphysiological model.

Light is recognized as an accurate and noninvasive tool for stimulating excitable cells. Here, we report on a non-genetic approach based on organic molecular phototransducers that allows wiring- and electrode-free tissue modulation. As a proof of concept, we show photostimulation of an in vitro cardiac microphysiological model mediated by an amphiphilic azobenzene compound that preferentially dwells in the cell membrane. Exploiting this optical based stimulation technology could be a disruptive approach for highly resolved cardiac tissue stimulation.

Emergency laparoscopic ileo-colic resection and primary intracorporeal anastomosis for Crohn's acute ileitis with free perforation and faecal peritonitis: first ever reported laparoscopic treatment.

INTRODUCTION: Laparoscopy for abdominal surgical emergencies is gaining increasing acceptance given the spreading of advanced laparoscopic skills among modern surgeons, as it may allow at the same time an accurate diagnosis and appropriate treatment of acute abdomen. The use of the laparoscopic approach also in case of diffuse peritonitis is now becoming accepted provided hemodynamic stability, despite the common belief in the past decades that such severe condition represented an indication for conversion to open surgery or an immediate contraindication to continue laparoscopy. Crohn's Disease (CD) is a rare cause of acute abdomen and peritonitis, only a few cases of CD acute perforations are reported in the published literature; these cases have always been approached and treated by open laparotomy. CASE DESCRIPTION: We report on a case of a faecal peritonitis due to an acute perforation caused by a terminal ileitis in an undiagnosed CD. The patient underwent diagnostic laparoscopy followed by a laparoscopic ileo-colic resection and primary intracorporeal anastomosis, with a successful postoperative outcome. CONCLUSIONS: Complicated CD has to be considered within the possible causes of small bowel non-traumatic perforation. Emergency laparoscopy with resection and primary intra-corporeal anastomosis can be feasible and may be a safe and effective minimally invasive alternative to open surgery even in case of faecal peritonitis, in selected stable patients and in presence of appropriate laparoscopic colorectal surgical skills and experience. To the best of our knowledge the present experience is the first ever reported case managed with a totally laparoscopic extended ileocecal resection with intracorporeal anastomosis in case of acutely perforated CD and diffuse peritonitis.

Prognostic relevance of cell proliferation in major salivary gland carcinomas.

Several proliferation markers, such as DNA ploidy, Ki67, MiB1 and proliferating cell nuclear antigen have been shown to correlate with clinical course and prognosis in several epithelial tumours and lymphomas. In the present study, the prognostic relevance of these markers was evaluated in major salivary gland carcinomas. A sample of 36 cases out of 85 patients submitted to surgery for major salivary gland carcinomas at our institution between 1987 and 1997 were studied. The sample comprised 8 adenoid-cystic carcinomas, 6 ductal carcinomas, 11 mucoepidermoid carcinomas and 11 acinic cell carcinomas. Follow-up ranged from 1 to 12 years (mean 6.2). In some patients, DNA ploidy (euploid or aneuploid) was studied by flow cytometry. In others, proliferation activity was studied by means of monoclonal antibody MiB1, identifying cells in the proliferative cycle. In some patients, both techniques were used. Follow-up was related to these indices, TNM and stage. Even if ploidy suggested a favourable outcome in diploid cancer (13 favourable vs. 2 unfavourable) and poor outcome in aneuploid cancer (4 favourable vs. 5 unfavourable), the difference was not statistically significant with p = 0.06 in Fisher's exact test. Instead, the proliferative tumour cell fraction, evaluated by MiB1, was statistically correlated with prognosis. Comparing survival curves by Log rank Test it yielded p = 0.007 using an MiB1 cut-off of 5. Applying a cut-off of 20 yielded p = 0.001. Of particular interest were MiB1 values in acinic cell carcinomas for which grading is challenging and lacks consensus. In our group of acinic cell carcinomas, survival correlated with values of MiB1 > or < 15 with p = 0.009 in Log rank test. In conclusion, despite a trend towards correlation between ploidy and prognosis, the present study yielded p = 0.06, whereas the proliferative fraction assessed by MiB1 was significantly correlated with outcomes. Indeed, "growth fraction" in acinic cell carcinomas may stratify different classes of risk.

Subungual keratoacanthoma: a variant of verrucous squamous cell carcinoma of the skin.

A case of so-called subungual keratoacanthoma is reported. Clinically and morphologically, this lesion is similar to a verrucous carcinoma of the skin. It is possible that subungual keratoacanthoma and carcinoma cuniculatum (verrucous carcinoma) are different aspects of the same entity.