Showing papers by "Giuseppe Coppola published in 2009"

Mitochondria and human preimplantation embryo development

Abstract: Human reproduction, like all biological systems, is characterised by a large level of variability. In this field, the variability is observed as a large difference in implantation potential of human embryos developing in vitro, despite similarities in observable parameters such as rate of development and morphology of these embryos. One of the underlying factors that determines developmental potential in these embryos is the availability of energy in the form of ATP for development. Here, we suggest that, despite the evidence suggesting that mitochondrial metabolism is relatively inactive during preimplantation embryo development, aerobic (mitochondrial) metabolism contributes a major role in the supply of ATP. A second pathway, anaerobic respiration, is also active and the two pathways work in synchrony to supply all the ATP necessary. We discuss the differences in the two forms of energy production and suggest that, although anaerobic respiration can supplement deficiencies in the energy supply in the short term, this is not sufficient to substitute for aerobic respiration over long periods. Therefore, we suggest that deficiencies in the levels of aerobic respiration can explain variability in the implantation potential of apparently equivalent embryos.

A porous silicon-based Bragg grating waveguide sensor for chemical monitoring

Abstract: We have fabricated, and characterized a Bragg grating, having a pitch of 10 μm, directly etched on a porous silicon-based planar waveguide to be used as an optical sensor for chemical substances. The transmission spectrum of this device shows a well-defined peak in the near infrared wavelength region due to a high order resonance of the Bragg grating. On exposure to different volatile organic compounds the peak undergoes distinct shifts. The phenomenon is fast and completely reversible. Limits of detection of hundred of ppm can be estimated from the experimental data.

Mid-infrared tunable two-dimensional Talbot array illuminator

Abstract: We report the realization and characterization of a tunable, two-dimensional Talbot array illuminator for mid-infrared (MIR) wavelengths. A phase array, prepared by deposing tin-doped indium oxide electrodes on a square-lattice-geometry poled LiNbO3 sample, is illuminated by a difference-frequency generator emitting at 3 μm. Then, combining the electro-optic with the Talbot effect allows generation of a variety of light patterns under different values of distance and external electric field. Several potential applications with great relevance to the MIR spectral region are discussed.

Back-illuminated silicon resonant cavity-enhanced photodetector at 1550 nm

Abstract: In this paper a novel photodetector at 1550 nm, working at room temperature and completely silicon compatible, is reported. The detector is a resonant cavity-enhanced structure incorporating a Schottky diode back-illuminated and its working principle is based on the internal photoemission effect. The device performances in terms of responsivity are numerically calculated for different values of bottom reflectivity. Finally, a preliminary device was realized and characterized in order to validate the theoretical results.

A cytogenetic study of breeding boars in Canada.

Abstract: Chromosome abnormalities are well known for their negative impact on the reproductive performance of carriers Such abnormalities could have severe effect on animal industries which rely heavily on efficient reproduction We conducted a cytogenetic survey of breeder pigs from 4 different Canadian farms to investigate the frequency of chromosome abnormalities and to assess their reproductive impact on pig populations Our study revealed that 50% of the 'hypoprolific' boars and 25% of the young boars raised for service in artificial insemination were carriers of chromosome anomalies while no chromosome defect was noted in any of the 'proven' breeder boars G-banding technique to determine the type of abnormalities detected 3 previously unreported translocations involving chromosomes 1 and 6, chromosomes 10 and 13 and chromosomes 9 and 14 The reciprocal nature of these translocations was confirmed either using fluorescent in situ hybridization (FISH) technique or immunostaining for synaptonemal complex delineation and were named rcp(1;6)(p22,q12), rcp(10;13), and rcp(9;14) (p24;q27), respectively Prolificacy of 1/6 and 10/13 translocation carriers was noted to be reduced by more than 40% compared to their normal counterparts while it was reduced by 26% in carriers of the 9/14 translocation Carriers of 1/6 and 9/14 translocations displayed a higher repeat breeding tendency, compared to their herd average (5 and 16%, respectively) While for the 9/14 translocation the prevalence of stillbirths was lower than that in their herd [87 vs 104% (p < 0001)] The present results, albeit based on a relatively small number of pigs, indicate that the prevalence of chromosome abnormalities could be much higher in Canadian pigs compared to that reported in European pigs and underline the urgent need to initiate cytogenetic screening programs as one of the effective ways to reduce reproductive problems in Canadian pig populations

Label-free biosensing by means of optical micro-ring resonator

Abstract: Micro-ring resonators have been widely employed, in recent years, as wavelength filters, switches and frequency converters in optical communication circuits, but can also be successfully used as transducing elements in optical sensing and biosensing. Their operation is based on the optical coupling between a ring-shaped waveguide and one or more linear waveguides patterned on a planar surface, typically an input and an output waveguide. When incoming light has a wavelength which satisfies the resonance conditions, it couples into the micro-ring and continuously re-circulates within it. A fraction of this resonant light escapes the micro-ring structure and couples into the output waveguide. The presence of a target analyte over the top surface of the micro-ring (i.e. within the evanescent field) changes the effective refractive index of the mode propagating into the structure, thus causing a shift in resonance wavelength which can be determined by monitoring the spectrum at the output port. Proper functionalization of the micro-ring surface allows to add selectivity to the sensing system and to detect specific interaction between a bioprobe and its proper target (e.g. protein-ligand, DNA-cDNA interactions). We present our preliminary results on the design of micro-ring resonators on silicon-oninsulator substrate, aimed at selective detection of several biomolecules. The design of the structure has been accomplished with the help of FDTD 2D numerical simulations of the distribution of the electromagnetic fields inside the waveguides, the micro-ring and near the micro-ring surface. Furthermore, all the functionalization reactions and the bio/non-bio interfaces have been studied and modelled by means of spectroscopic ellipsometry.

Microfluidic system based on the digital holography microscope for analysis of motile sperm

Abstract: Digital holography (DH) has been employed in the retrieval of three dimensional images of bull's sperm heads. The system allows a three dimensional analysis of the sperm morphology by means of a Digital Holographic Microscope (DHM). Microscopic holography measurements are performed by projecting a magnified image of a microscopic hologram plane onto a CCD plane. This could constitute the basis of an alternative method for the zoothecnic industry aimed at the investigation of morphological features and the sorting of the motile sperm cells. Indeed, one of the main advantages of digital holography consists in its full non-invasivity and in the capability of investigating the shape of the sperm cells without altering their characteristics. In particular the proposed technique could be applied to investigate the frequency of aberrant spermatozoa. Until now, in fact, such industrial investigations have been mainly performed by means of specific painting probes: unfortunately this technique dramatically reduces the vitality of the sperm cells and can even cause chromosome aberration, making them useless for the zootechnical applications.

Micro and nanophotonics in silicon: new perspectives and applications

Abstract: In the last few years, silicon photonics has been characterized by a wide range of applications in several fields, from communications to sensing, from biophotonics to the development of new artificial materials. In this communication, we report a review of the main results obtained in our laboratories in design, fabrication and characterization of new silicon-based optical structures and devices, including metamaterials, photodetectors, raman light amplifiers, and porous silicon based bio-chemical sensors and biochips. Future perspectives in integration of silicon based MEMS and MOEMS are also presented.

Imaging 3-D Objects by Extending the Depth of Focus in Digital Holography

Abstract: Digital holography is an imaging technique offering both sub-wavelength resolution and real-time capabilities to record 3-D objects using the interference between an object wave and a reference wave captured by an image sensor such as a CCD array. The basic advantage of digital holography is that it can quantitatively extract the three-dimensional (3-D) information of the object from the numerical reconstruction of a single digitally recorded hologram [1,2,3]. Since the information of the optically interfering waves is stored in the form of matrices, the numerical reconstruction process enables full digital processing of the holograms and offers many more possibilities than conventional optical processing. It is possible to numerically focus on any section of the 3-D volume object without mechanical focusing adjustment. This opens the field to a variety applications, such as 3-D microscopic investigations and real-time imaging of biological specimens where wavelength-scanning digital interference holography [4] is used to reconstruct the 3-D volume from a set of scanning tomographic images, hybrid holographic microscopy [5], 3-D microscopy by optical scanning holography [6], phase shifting digital holog-