Search

Microcontrollers and single-board computers are widespread tools for innovative educational labs, for prototyping and for accomplish everyday tasks by expert users. Moreover, these modules are opening new exciting possibilities in the area of biological and chemical assays. In this study a Raspberry Pi computer assembled with 3D printed parts and inexpensive opto-electronic components were employed to analyse the antioxidant capacity of several bottled tea performing diphenylpicryl-hydrazyl (DPPH) tests. A dedicated python software allowed the execution of the analysis controlling the device through a small LCD touch screen or remotely through secure connections with other devices. The Raspberry Pi-based measurements were compared with a research-grade spectrophotometer showing excellent correlation (R2 = 0.9996) and no significant differences (p

Single-board computers (SBCs) and microcontroller boards (MCBs) are extensively used nowadays as prototyping platforms to accomplish innovative tasks. Very recently, implementations of these devices for diagnostics applications are rapidly gaining ground for research and educational purposes. Among the available solutions, Raspberry Pi represents one of the most used SBCs. In the present work, two setups based on Raspberry Pi and its CMOS-based camera (a 3D-printed device and an adaptation of a commercial product named We-Lab) were investigated as diagnostic instruments. Different camera elaboration processes were investigated, showing how direct access to the 10-bit raw data acquired from the sensor before downstream imaging processes could be beneficial for photometric applications. The developed solution was successfully applied to the evaluation of the oxidative stress using two commercial kits (d-ROM Fast, PAT). We suggest the analysis of raw data applied to SBC and MCB platforms in order to improve results.

Optical fiber-based biosensors are an emerging field of research with an extremely broad area of possible applications and a disruptive potential to turn the paradigm known as lab-on-fiber into reality. In the past few years, a variety of system choices has been explored, ranging from the type of sensing fiber, to the optical transducing element, to possible sensing amplification strategies. We revise some of the possible approaches to the design of a biosensor, highlighting their advantages and disadvantages, based on previous literature and on the experience of our research groups. The discussion is focused onto DNA sensing systems, especially in a label-free format, where the hybridization and recognition of the sought DNA sequence is translated directly into a modification of the optical fiber properties.

Objectives: The introduction of diode lasers in dentistry had several advantages, principally consisting on the reduced size, reduced cost and possibility to beam delivering by optical fibbers. Up today only the wavelengths around 810 and 980 nm were the most utilized in oral surgery but recently more different lasers had been proposed. The aim of this study was to compare the efficacy of four diode laser wavelengths (810, 980, 1470 and 1950 nm) for the ablation of soft tissues. Material and methods: Specimens were surgically collected from the dorsal surface of four bovine tongues and irradiated by four different diode wavelengths. Thermal increase was measured by two thermocouples, the first at a depth of 0.5 mm, and the second at a depth of 2 mm. Initial and final surface temperatures were recorded by IR thermometer. Epithelial changes, connective tissue modifications, presence of vascular modification and incision morphology were histologically evaluated by two blind pathologists. Results: The time necessary to perform the excision varied between 271 seconds (808 nm, 2W) and 112 seconds (1950 nm, 4W). Temperature increase superficial level varied from 16.3° (980 nm, 4W) and 9.2° (1950 nm, 2 W). The most significant deep temperature increase was recorded by 980 nm, 4 W (17.3°) and the lowest by 1950 nm, 2 W (9.7°). The width of epithelial tissue injuries varied between 74 pm from 1950 nm diode laser at 2 W to 540 pm for 1470 nm diode laser at 4 W. Conclusion: The quality of incision was better and the width of overall tissue injuries was minor in the specimens obtained with higher wavelength (1950 nm) at lower power (2W).

The cancer risk of patients with inflammatory bowel diseases (IBD) has not been well documented in southern Europe. This study aimed to evaluate the overall pattern of cancer risk among patients with IBD in Friuli Venezia Giulia, northeastern Italy. A population-based cohort study was performed through a record linkage between local healthcare databases and the cancer registry (1995–2013). We identified 3664 IBD patients aged 18–84 years, including 2358 with ulcerative colitis (UC) and 1306 with Crohn’s disease (CD). Sex- and age-standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) were used to compare the cancer incidence of IBD patients with the general population. The cumulative cancer risk among IBD patients reached about 10% after 10 years of follow-up. A total of 246 cancers occurred among UC patients (SIR = 1.05, 95% CI: 0.92–1.19), and 141 among CD patients (SIR = 1.20, 95% CI: 1.01–1.41). As compared with the general population, no increased risk of colorectal cancers was observed for either UC or CD patients, whereas the risk of anal cancer was significantly elevated among UC patients (SIR = 6.03, 95% CI: 1.24–17.60). Increased risks were seen for specific extra-intestinal cancers, including corpus uteri (SIR = 2.67, 95% CI: 1.07–5.50) and kidney (SIR = 2.06, 95% CI: 1.03–3.69) among UC patients; thyroid (SIR = 5.58, 95% CI: 2.41–11.00) and skin non-melanoma (SIR = 1.86, 95% CI: 1.32–2.55) among CD patients. This population-based study showed that both UC and CD patients had a colorectal cancer risk similar to that of the general population. However, they were at a higher risk of developing certain extra-intestinal cancer types. Although detection biases cannot be excluded, the study findings pointed to a role of long-standing exposures to immunosuppressive therapies, underlying disease status, as well as the interactions with lifestyle factors. Our findings lent additional support to the need for monitoring the cancer burden in this at-risk population.

Poster: "ECR 2015 / B-0456 / The impact of Gadolinium-based contrast agent in the assessment of Crohn’s disease activity: Is it contrast agent injection necessary?" by: "E. Quaia, M. Pontello, R. Angileri, M. A. Cova; Trieste/IT"

The CdTe thin film technology for photovoltaics (PV) is attractive because of its potential low cost and good performance. In thin film technology the efficiency of large area cells can be maintained if small segments are interconnected in series to reduce the photocurrent and resistance losses. In respect to this, the scribing process is critical for the performance of the device. Today, fiber lasers represent the most advanced and cheap technology that can be used in PV industry to carry out the cuts, needed for the monolithic integration, at different deposition stages. We will present our results on the scribing of CdTe thin film solar cells by means of fiber lasers, with pulse duration of a few nanoseconds and solid state lasers in the picosecond regime. The quality of the scribing was evaluated by optical and scanning electron microscopy. Finally, mini-modules with a total area of 10 × 10 cm 2 were fabricated, in which the cells were interconnected in series by means of a scribing system, equipped with a fiber laser with the same characteristics of the system mounted on production lines. The mini-modules were characterized by photovoltaic and electrical measurements.

The inscription of relief Bragg grating reflectors on the capillary walls of a solid-core photonic crystal fiber (PCF) using laser radiation is presented. The inscription method followed is based on the infiltration and adsorption of a thin layer of toluene on the capillaries of the PCF and the subsequent exposure of the infiltrated fiber using 248-nm excimer laser radiation and phase mask interference. Gratings are characterized spectrally and by scanning electron microscopy while their sensing capabilities are exemplified by infiltrating them with organic solvents. Thermal studies revealed that the gratings exhibit high thermal endurance characteristics, withstanding tens of hours annealing at 950°C.

Background: The Er:YAG laser in conservative dentistry is. good alternative to conventional instruments. Though several studies show the advantages of these devices, some drawbacks and unsolved problems are still present, such as the cost of the device and the large dimensions of the equipment. Purpose: In the present study, the effectiveness of dental surface ablation with a picosecond infrared diode-pumped solid-state (DPSS) laser was investigated. In vitro tests on extracted human teeth were carried out, with assessment of the ablation quality in the tooth and thermal increase inside the pulp chamber. Materials and Methods: A solid-state picosecond laser was used for the experiments. The samples were exposed to laser energy at 1064 nm at a frequency of 30 kHz and a 500 ps pulse width. The target teeth were cooled during exposures. The internal temperature of the pulp chamber was monitored with. thermocouple. Results: Optical microscope images showed effective ablation with the absence of carbonisation and micro-cracks. The cooling maintained the temperature rise in the pulp chamber below the permitted 5.5°C. Discussion: The main problem with the use of lasers in dentistry when teeth are the target is the heat generated in the pulp chamber of the target teeth. With lasers operating in the femtosecond mode, a better management of the internal temperature is possible, but is offset by the high cost of such devices. With the ps domain system used in the present study together with cooling using chilled water, effective and clean ablation could be achieved with a controlled thermal effect in the pulp chamber. Conclusions: In this preliminary study with a picosecond domain DPSS laser using water cooling for the target, effective hard tissue ablation was achieved keeping the thermal increase in the pulp within the permitted range. The results suggest that this system could be used in clinical practice with appropriate modifications.

Objectives: The introduction of diode lasers in dentistry had several advantages, principally consisting on the reduced size, reduced cost and possibility to beam delivering by optical fibbers. Up today only the wavelengths around 810 and 980 nm were the most utilized in oral surgery but recently more different lasers had been proposed.

Rationale and Objectives: To define the best independent predictors for active inflammation in patients with Crohn disease (CD) examined by contrast-enhanced magnetic resonance (MR) enterography. Materials and Methods: Ninety-one patients (47 men and 44 women; aged 39.58 17.1 years) with a diagnosis of CD; CD activity index (CDAI)$150 (n = 19 patients) or

Purpose To assess whether contrast material-enhanced ultrasonography (US) can be used to differentiate responders from nonresponders among patients with clinically active Crohn disease after 6 weeks of pharmacologic treatment. Materials and Methods This prospective study was approved by our ethics committee, and written informed consent was obtained from all patients. Fifty consecutive patients (26 men and 24 women; mean age, 34.76 years ± 9) with a proved diagnosis of active Crohn disease who were scheduled to begin therapy with biologics (infliximab or adalimumab) were included, with enrollment from June 1, 2013, to June 1, 2015. In each patient, the terminal ileal loop was imaged with contrast-enhanced US before the beginning and at the end of week 6 of pharmacologic treatment. Time-intensity curves obtained in responders (those with a decrease in the Crohn disease endoscopic index of severity score of 25-44 before treatment to 10-15 after treatment, an inflammatory score

An outcladding sensitized label-free DNA biosensor is developed based on tilted fiber Bragg gratings. The biosensor, functionalized with peptide nucleic acid (PNA) probes, is based on a double tilted fiber Bragg grating that forms a modified Fabry-Perot core-cladding closed-loop cavity. Interference is set up between an injected guided mode and the reflected core mode and cladding modes created by the light scattered by the tilted gratings, leading to the generation of interference fringes within both these spectral notches. When the DNA binds to the PNA probes attached onto the fiber cladding, a refractive index change occurs at the cladding-PNA interface and the fringe visibility changes accordingly. Real-time spectral measurement results are reported, showing that a 10-nM DNA solution induces a 10% modulation of the corresponding fringes visibility. Cycling tests are performed for measuring and checking the repeatability of the sensor.

The feasibility of a biosensor for DNA detection based on suspended-core photonic crystal fibers is investigated. The possibility of functionalization of the hole surface, which allows DNA strand binding, is demonstrated, along with the selective detection of DNA through hybridization of immobilized peptide nucleic acid probes with their full-complementary and mismatched DNA segments.

In this work the application of different laser wavelengths, in combination with different photosensitizing dyes, to bacterial cultures, in liquid or solid mean, has been investigated. Two types of Streptococcus mutans cultures have been used for the experiments, inside agar and saline solution. Three different laser wavelengths have been applied to the bacterial cultures together with a photosensitizing dye: red diode (650 nm) on cultures stained with Toluidine Blue, blueviolet diode (450 nm) on cultures stained with Curcumin and KTP laser (532 nm) on cultures stained with Erythrosine. The choice of the dye has been made considering the color affinity with the used wavelength. Tests without dyes have also been performed. Experimental results show that the maximum inhibition of bacterial growth with the blue laser has been obtained in a saline solution with a growth of 40.77%. While the combination with Curcumin lead to an inhibition growth of about 99.1%, for a laser fluence of 30J/cm 2 . No inhibition has been observed using the red laser in saline solution without dye, while the combination with Toluidine Blue resulted in a 100% inhibition growth for 20 and 30 J/cm 2 fluences. An inhibition growth of just 16.26% has been obtained with the use of KTP laser in saline solution without dye. The use of Erythrosine had the effect of a complete inhibition growth. From the obtained results it is possible to observe that the combination of laser wavelength with a particular photosensitizing dye can dramatically increase the bacterial growth.

The introduction of diode lasers in dentistry has several advantages, mainly consisting on the reduced size, reduced cost and possibility to beam delivering by optical fibers. At the moment the two diode wavelengths normally utilized in the dental field are 810 and 980 nm for soft tissues treatments. The aim of this study was to compare the efficacy of four different diode wavelengths: 810, 980, 1470 and 1950 nm diode laser for the ablation of soft tissues. Several samples of veal tongue were exposed to the four different wavelengths, at different fluences. The internal temperature of the soft tissues, in the area close to the beam, was monitored with thermocouple during the experiment. The excision quality of the exposed samples have been characterized by means of an optical microscope. Tissue damages and the cut regularity have been evaluated on the base of established criteria. The lowest thermal increase was recorded for 1950 nm laser. Best quality and speed of incision were obtained by the same wavelength. By evaluating epithelial, stromal and vascular damages for all the used wavelengths, the best result, in terms of “tissue respect”, have been obtained for 1470 and 1950 nm exposures. From the obtained results 1470 and 1950 nm diode laser showed to be the best performer wavelengths among these used in this “ex vivo” study, probably due to their greatest affinity to water.

The introduction of photo-activators, with absorption spectra in the violet region, in composite resins raised interest in the use of 405 nm diode lasers for polymerization. The purpose of this research is the evaluation of the resins polymerization by means of violet diode laser compared to traditional lamps. Two different resins have been used for the experiments: Filtek Supreme XT flow (3M ESPE, USA) and Tetric Evo flow (Ivoclar, Vivadent). The photo-activator used is Camphoroquinone, alone, or in combination with Lucirin TPO. The resins have been cured with an halogen lamp (Heliolux DXL, Vivadent Ivoclar, Austria), a broadband LED curing light (Valo Ultradent, USA) and a 405 nm laser (Euphoton, Italy). The measure of cure depth, of the volumetric shrinkage, and the conversion degree (DC%) of the double bond during the curing process have been evaluated. A composite layer of 3 mm was cured in Filtek Supreme resin (Camphoroquinone activator), lower if compared to the use of the other two light sources. Tests on Tetric Evo (Camphoroquinone + Lucirin) didn’t show any improvement of the use of laser compared to the halogen lamp and the broadband LED. By measuring the volumetric shrinkage the laser induced the lower change with both the composites. In terms of DC% the lower performance was obtained with the laser. Considering that the polymerization process strongly depends on the kind of composite used the effectiveness of 405 nm laser proved to be lower than halogen lamps and broadband LEDs.

Plastic materials are characterised by low absorption to laser radiation of wavelength < 2 μm; yet, above a certain threshold fluence non-linear absorption mechanisms can lead to efficient material ablation. Several studies on PMMA exist in the literature [1], whilst only a limited number of work presents pulsed laser processing of polypropylene (PP) and polyethylene (PE) [2,3]. In the present study, thin PP and PE films, 20 μm and 50 μm thick respectively, and their multi-layer combinations with aluminium (AL) as Triplex (PP 20 μm-AL 9 μm-PP 20 μm) and Duplex (PP 20 μm-AL

Bio-functionalization of inner surfaces of all silica Hollow Core–Photonic Crystal Fibers (HC-PCF) has been investigated. The approach is based on layer-by-layer self-assembly Peptide Nucleic Acid (PNA) probes, which is an oligonucleotide mimic that is well suited for specific DNA target recognition. Two kinds of HC-PCFs have been considered: a photonic Bragg fiber and a hollow core (HC-1060) fiber. After spectral characterization and internal surface functionalization by using PNA probes, genomic DNA solutions from soy flour were infiltrated into the fibers. The experimental results indicate that hybridization of the complementary strand of target DNA increases the thickness of the silica layer and leads up to the generation of surface modes, resulting in a significant modulation of the transmission spectra. Numerical analysis confirms such behavior, suggesting the possibility to realize biological sensing.

Single layer thin-film materials such as aluminum, polyethylene, polypropylene, and their multi-layer combinations such as aluminum-paper have been exposed to different laser radiation. A wide number of samples have been processed with 10 - 12.5 ns IR and Green, and 500 - 800 ps IR laser radiation at different translating speeds ranging from 50 mm/s to 1 m/s. High quality incisions have been obtained for all tested materials within the experimental conditions. The presented results provide the necessary parameters for an efficient cut and processing of the tested materials, for the employment of pulsed laser sources in the packaging industry, allowing the laser to prevail in lieu of more costly and energy intensive methods. © 2014 SPIE.

Our aim was to assess whether the Helicobacter pylori population recovered from experimentally infected mice show heterogeneity in cag genotypes. Wild-type FVB/N mice were challenged with strain Hp1 and sacrificed 8 weeks later. Direct PCR on gastric tissue was performed using primers for glmM and cagA, and for these two genes and for cagE and virB11 using DNA from the infecting and the emerging strains. The gastric tissues of two of five mice were PCR+ for glmM but not cagA. For the infecting strain, the PCRs for all four genes studied were strongly positive, but the sweeps from the emerging strains from both mice gave weaker signals for cagA and cagE. Examination of single colonies showed reduced or absent signals for cagA and cagE in relation to glmM and virB11. Serial dilution PCR of sweep isolates from the mice showed a 10- to 100-fold decrease in cagA signal compared to the infecting strain. The decrease of cagA and cagE, but not virB11, amplification and lack of cagA hybridization in Southern blots indicates a selective loss of the right half of the cag island during murine infection. This phenomenon is consistent with host-induced adaptive changes of cag genotype in the population of colonizing H. pylori cells.

Relief Bragg and long period gratings are inscribed inside the capillaries of microstructured optical fibres using laser induced backside wet etching method. Inscription results are presented and discussed with respect to machining and scattering effects.

The label-free detection of DNA strands based on Double Tilted Fiber Bragg Grating (DTFBG) has been demonstrated. The external fiber surface has been modified with peptide nucleic acid (PNA). The changes of the interference fringes visibility of the grating, due to the PNA-DNA binding, proved the occurred fiber hybridization. The re-use of the fiber for multiple measurements and the selectivity of the sensor have been also investigated

In this work the inner surface of a microstructured optical fiber, where a Bragg grating was previously inscribed, has been functionalized using peptide nucleic acid probe targeting a DNA sequence of the cystic fibrosis disease. The solution of DNA molecules, matched with the PNA probes, has been infiltrated inside the fiber capillaries and hybridization has been realized according to the Watson - Crick Model. In order to achieve signal amplification, oligonucleotide-functionalized gold nanoparticles were then infiltrated and used to form a sandwich-like system. Experimental measurements show a clear wavelength shift of the reflected high order mode for a 100 nM DNA solution. Several experiments have been carried out on the same fiber using the identical concentration, showing the same modulation and proving a good reproducibility of the results, suggesting the possibility of the reuse of the sensor. Measurements have been also made using a 100 nM mis-matched DNA solution, containing a single nucleotide polymorphism, demonstrating the high selectivity of the sensor.

The pico- and nano-second ablation thresholds and subsequent pulse-energy cut-depth and width relationships of aluminium, polypropylene (PP), polyethylene (PE) and their various thin-film combinations have been determined at 515 nm and 1064 nm. High quality incisions were obtained for all structures within certain parameter ranges. All ablation thresholds were found to be functions of the temporal pulse-width. Numerical simulations revealed the underlying mechanisms as phase explosion and thermal conduction. The presented results provide necessary parameters for the efficient cut and scribe of such materials, allowing the laser to prevail in lieu of more costly and energy intensive methods.

The growing demand for high productivity in the thin-film photovoltaic module industry, together with the request for more and more efficient devices, needs high-performance laser-scribing. The results of scribing tests on CdTe and CIGS solar cells samples are here presented. A comparison between the scribes obtained with ns regime fiber lasers, and a ps regime diode pumped solid state laser will be also reported.

The effects of thermally-induced refractive index change on the guiding properties of different large mode area fibers have been numerically analyzed. A simple but accurate model has been applied to obtain the refractive index change in the fiber cross-section, and a full-vector modal solver based on the finite-element method has been used to calculate the guided modes of the fibers operating at high power levels. The results demonstrate that resonant structures added to the fiber cross-section can be exploited to provide efficient suppression of high-order modes with a good resilience to thermal effects.

The pulsed laser ablation of 20 micron thick aluminium foil is investigated by exposing moving samples to picosecond pulses of wavelength 1064nm and nanosecond pulses of wavelength 515nm and 1030nm. Ablation thresholds and depths are determined for a range of conditions using an optical microscope and 3D optical profiler. Complete three-dimensional crater profiles for single and multiple pulses are presented. The results reveal a variation in ablation threshold with wavelength, pulse duration and the number of pulses; a large reduction is observed for picosecond pulses. Ablation rates per pulse are expressed by general equations and found to vary strongly with both laser type and the number of pulses. The green nanosecond laser is found to ablate most efficiently for fluences above 10J/cm2, whilst the picosecond source is instead advantageous for low fluences. A large reduction in ablation depth per pulse is observed with an increasing number of pulses. The present work affords prediction of scribe and cut parameters for the processing of thin aluminium layers and, more generally, characterises the driving parameters of pulsed picosecond and nanosecond laser ablation of metals.Copyright © 2013 by ASME

Results are presented on the laser etching of relief Bragg and long period grating on the capillary walls of solid core photonic crystal fibres. Preliminary results on gratings in hollow core fibers are also appended.

The FP7 EU funded ALPINE project is focused on the processing of new type of thin film CdTe and CIGS photovoltaic modules by means of pulsed fiber laser scribing. The latest results of scribing tests performed for different laser parameters for P1, P2 and P3 steps in both CdTe and CIGS solar cells are discussed showing examples for CdTe module processing.

The modal cut-off properties of Yb-doped Double-Cladding Photonic Crystal Fibers (DC-PCFs) with 19-cell core have been analyzed considering an innovative approach, where the avoided crossing between the guided modes and the highest-index cladding mode of the real fiber is taken as the cut-off condition. A finite element-based full-vector modal solver has been applied to calculate the modes of DC-PCFs with different normalized air-hole size and core refractive index. Simulations have shown the possibility to find generalized results for the modal cut-off wavelengths of 19-cell DC-PCFs.

The realization of a DNA biosensor based on Double Tilted Fiber Bragg Grating (DTFBG) for label-free detection has been demonstrated. To our knowledge this is the first time that a biosensor has been realized with such kind of device. The surface of the optical fiber has been functionalized with peptide nucleic acid (PNA) in order to capture DNA strands. The changes of the interference fringes visibility of the grating, due to the PNA-DNA binding, proved the occurred fiber hybridization. The re-use of the fiber for multiple measurements and the selectivity of the sensor have been also investigated.

Relief Bragg gratings are inscribed inside the capillaries of solid core photonic crystal fibres using 248nm laser radiation and toluene vapors. These gratings exhibit reflection extinction ratios greater than 20dB, while surviving up to 1200oC.

We present a new approach for developing a label-free biosensor for detection of DNA. The biosensor based on a biofunctionalized Double Tilt Fiber Bragg Grating transduces the presence of DNA into a change of visibility of fringes of its interference spectrum. Real-time spectral measurement results are reported, showing that a 10nM DNA solution induces a 10% modulation of the corresponding fringes visibility.

The feasibility of a DNA biosensor based on a long period grating inscribed in an optical fiber has been investigated. The sensor can perform a label-free detection, due to the functionalization of the optical fiber external surface with peptide nucleic acid probes matched with the DNA target strands. A wavelength shift of 1.2 nm for a 120 nM DNA solution has been measured. Fluorescence measurements have been also taken, in order to give a further proof of the fiber functionalization and hybridization.

Several studies have been presented on the photosensitivity and index engineering of phosphate glasses using high intensity ultraviolet [1, 2] lasers. These studies are of particular interest due to the increased number of applications of rare-earth codoped phosphate glasses in the development of high efficiency planar and fibre active components. We present results on the Bragg grating recording behavior and photosensitivity of an all-phosphate glass rare earth doped optical fibre, utilizing 248nm, 500fs laser radiation. In the grating inscription results presented, non-monotonic refractive index changes with respect to accumulated energy density are observed. This unique behavior resembles that of the Type IIA photosensitivity mechanism that usually occurs during grating recording in high-Ge doped silicate glass optical fibres using deep ultraviolet laser sources; however, never been observed before in grating recording in soft glasses, including phosphate glass fibres. Moreover, the origin of the negative refractive index changes induced, is investigated utilizing Knoop micro-hardness (HK) measurements, performed in irradiated and side-polished fibres [3]. The Bragg grating inscription was performed using a 248nm, 500-fs KrF excimer-dye laser system, at a 10Hz repetition rate. The experimental set-up used for grating recording was a double phase mask interferometer, being described elsewhere [4]. A single mode phosphate glass, Er/Yb codoped phosphate glass optical fibre, manufactured by INO-Canada, was exposed. The concentration of the rare earth dopants in the fibre are 0.90wt% for Er, and 7.0wt% for Yb.

The feasibility of a biosensor for DNA label-free detection, based on long period fiber gratings, has been investigated. The surface of the grating has been functionalized with Peptide Nucleic Acid (PNA) probes. DNA strands, matched with the PNA probes, have been immobilized on the surface itself. The possibility of a resonant wavelength shift in the transmission spectrum due to the DNA capture will be discussed. The problem of reusing the sensor for multiple measurements will also be addressed.

Microstructured optical fibers have the potential to provide improved performance relative to more traditional spectroscopic fiber sensors. In fact the manipulation of the geometry of the fiber cross section can allow to maximize the interaction of light and sample. Recently, solid air-suspended core fibers have been appointed as the most promising design for evanescent field sensing. In this kind of device, sensing is carried out through the interaction between evanescent tails of index-guided modes and sample, which fills cladding holes. Suspended core fibers are made by three silica webs joining in the fiber center and forming the core. This design can provide an evanescent field power fraction greater than any other structure previously proposed, together with a wide transmission band. In this paper, the electromagnetic field behaviour of the guided modes of a range of suspended-core fibers is investigated, using a full-vectorial finite element based modal solver. The impact of different design parameters and materials on guidance, the amount of power in the cladding and the possibility of obtaining effective single-mode guidance are also investigated.

Helicobacter pylori infecting strains may include colony subtypes with different cytotoxin-associated gene (cag) genotypes. We sought to determine whether the cag heterogeneity of infecting strains is related to the clinical outcome of infection. Gastric biopsies for culture and histologic study were taken from 19 patients infected with cagA-positive strains (6 with duodenal ulcer, 8 with atrophic gastritis, and 5 with nonatrophic gastritis). For each biopsy, DNA was extracted from 10 single colonies and from a sweep of colonies. Polymerase chain reaction (PCR) for cagA and cagE (both located in the right half of cag) and virB11 (located in the left half of cag) was performed. Random amplified polymorphic DNA PCR (RAPD-PCR) and sequencing of glmM PCR product were performed to verify strain identity of colonies with different cag genotypes. In all patients, PCR from sweeps were positive for cagA, showing that all specimens contained cagA-positive H. pylori subtypes. In 11 patients, PCR products from all colonies were positive for cagA, cagE, and virB11, but in 8 patients, PCR products from varying numbers of colonies were negative for 1 or more cag genes. RAPD-PCR and sequencing of glmM PCR product confirmed the strain identities of colonies with different cag genotypes. We detected cag deletions in 6 of 8, 2 of 5, and 0 of 6 patients with atrophic gastritis, nonatrophic gastritis, and duodenal ulcer, respectively (P = .02). In conclusion, changes in cag genotype in single colony isolates from subjects infected with cagA-positive H. pylori strains are more common in atrophic than in nonatrophic gastritis or duodenal ulcer. These findings are consistent with host-induced (acid secretion?) adaptive changes in cag genotype during infection.

The Helicobacter pylori chromosomal cluster of genes known as the cytotoxin-associated gene ( cag ) island may have different compositions in infecting strains. In this study, we analyzed 150 single colonies obtained from gastric biopsy specimens from 10 patients infected with cagA -positive H . pylori strains and sweep isolates (isolates harvested with sweep in different points of the plate) from 6 patients infected with cagA -negative strains. Three loci in the cag island ( cagA , cagE , and virB11 ) and the conserved gene glmM ( ureC ) were investigated by PCR. The levels of anti- H . pylori and anti-CagA antibodies in patient sera were also measured. For subjects infected with cagA -negative strains, all sweep isolates were also negative for cagE and virB11 , suggesting the complete absence of the cag island. For subjects infected with cagA -positive strains, most of the isolates were positive for all three genes studied, whereas 24.7% of the isolates had a partial or total deletion of the cag island. cagA , cagE , and virB11 were, respectively, present in 87.3, 77.3, and 90% of the colonies. The deletion of virB11 was always associated with the deletion of cagA and/or cagE . H . pylori colonies with different cag genotypes were isolated within a single gastric biopsy specimen from 3 of the 10 patients and were further characterized by random amplified polymorphic DNA (RAPD) analysis and by sequencing of an arbitrarily selected gene segment. Although the colonies had different cag genotypes, their RAPD profiles were highly similar within each patient, and the nucleotide sequences of the selected gene segment were identical. All of the patients had detectable antibodies against H . pylori , and 9 of 10 had anti-CagA antibodies. In conclusion, we show that a single infecting H . pylori strain may include variable proportions of colony subtypes with different cag genotypes. The extension of our analysis to patients with well-characterized gastric diseases may provide significant information on the relationship between cag genotypes and clinical outcomes of H . pylori infections.

Helicobacter pylori (H. pylori) is a major factor in determining the risk for development of gastric adenocarcinoma through the intermediate steps of atrophic gastritis and intestinal metaplasia. Because H. pylori infection is highly prevalent in asymptomatic populations and only a few people develop cancer, additional factors may influence the risk for development of cancer, once infection is established. Some factors may pertain to differences among bacterial strains. Because infection by H. pylori strains possessing cagA (cytotoxin-associated gene A), a gene encoding a high-molecular-weight immunodominant antigen (CagA), is associated with enhanced induction of gastritis, the aim of our study was to evaluate potential differences in the prevalence and intensity of atrophy and intestinal metaplasia between CagA-positive and CagA-negative H. pylori-infected patients.Eighty H. pylori-infected patients among 120 consecutive dyspeptic patients referred for upper gastrointestinal endoscopy were studied. Six bioptic specimens were taken from the gastric antrum: five for histological examination, and one for urease test. The H. pylori status was determined by histology, CLO test, and serology (in a standardized ELISA) for serum IgG and IgA directed to H. pylori. The CagA status was determined by Western blotting to detect serum IgG antibodies to CagA. Gastritis was classified according to the Sydney System. A score from 0 to 3 was assigned to each of the following morphological variables: atrophy, intestinal metaplasia, and mononuclear and neutrophilic cell infiltration. The association between CagA status and histological features was assessed by means of the chi2 test for trend.Among the 80 H. pylori-infected patients 53 (66%) were CagA seropositive and 27 (34%) were CagA seronegative. The mean age of the two groups was similar. CagA-positive patients had significantly higher scores for atrophy (p = 0.006), intestinal metaplasia (p = 0.01), and mononuclear (p0.001) and polymorphonuclear (p = 0.002) cell infiltration than did CagA-negative patients. No differences in contrast, were found for H. pylori density.Infection with CagA-positive H. pylori strains is associated with an increased prevalence and intensity of antral atrophy and intestinal metaplasia, in addition to higher degrees of gastritis. Our results seem to suggest that the CagA status could be a helpful parameter to define a subgroup of H. pylori-infected patients at increased risk of developing gastric adenocarcinoma.

Microstructured optical fibers (MOFs) and photonic crystal fibers (PCFs) offer advanced photonic and microfluidic functionalities in a single, integrated platform. This unique combination constitutes the main axis for the emerging “lab-in-fiber” protocol. The microcapillaries of MOFs and PCFs can be used as a lab bench for attaching molecules, infiltrating nanomaterials or performing photochemical processes, being useful in sensors and actuators development.

A young man with a previous history of episodes of mild solid food dysphagia was admitted with a total dysphagia. The esophagogastroduodenoscopy (EGDS) showed an extensive disruption of mucosal layer with a cul-de-sac in the lower part of the esophagus. Soon after the procedure, the patient suffered from an acute chest pain and subsequent CT scan demonstrated an intramural circumferential dissection of thoracic esophagus, and a mediastinal emphysema. An emergency right thoracotomy was performed, followed by a total esophagectomy with esophagogastroplasty and jejunostomy. The histopathology confirmed that mucosal and submucosal layers were circumferentially detached from muscular wall and showed an eosinophilic infiltration of the whole organ with necrosis and erosions of mucosal, submucosal and muscular layers. The diagnosis was esophageal perforation in eosinophilic esophagitis.