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D Coscia

Publications and source records attributed to D Coscia.

At least 19 recordsLinked to original sources
PubMed2002

Gas chromatography for in situ analysis of a cometary nucleus. IV. Study of capillary column robustness for space application.

As part of the development of the European Space Agency Rosetta space mission to investigate a cometary nucleus, the selection of columns dedicated to the gas chromatographic subsystem of the Cometary Sampling and Composition (COSAC) experiment was achieved. Once the space probe launched, these columns will be exposed to the harsh environmental constraints of space missions: vibrations, radiation (by photons or energetic particles), space vacuum, and large temperature range. In order to test the resistance of the flight columns and their stationary phases, the columns were exposed to these rough conditions reproduced in the laboratory. The comparison of the analytical performances of the columns, evaluated prior and after the environmental tests, demonstrated that all the columns withstand space constraints, and that their analytical properties were preserved. Therefore, all the selected capillary columns, even having porous layer or chiral stationary phases, were qualified for space exploration.

Chromatography, Gas↗
PubMed2002

Gas chromatography for in situ analysis of a cometary nucleus III. Multi-capillary column system for the cometary sampling and composition experiment of the Rosetta lander probe.

The cometary sampling and composition (COSAC) experiment is one of the principal experiments of the surface lander probe of the European Space Agency Rosetta mission to be launched in January 2003. The instrument is designed for the in situ chemical analysis of a cometary nucleus as the details of the nucleus composition are of primary importance for understanding both the formation of the solar system, and the origin of life on Earth. The COSAC experiment consists of an evaporation/pyrolysis device and two analytical systems: a multi-column gas chromatograph and a high-resolution time-of-flight mass spectrometer which may either be operated alone or in a coupled mode. The gas chromatograph includes five general purpose chromatographic columns and three chiral ones, all mounted in parallel. Taking into account the chemical species potentially present in the cometary nucleus as well as the space constraints, a set of five complementary columns was selected to perform the separation and identification of the compounds present in the cometary nucleus. This set of columns includes a carbon molecular sieve porous-layer open tubular (PLOT) column used for the separation of both the noble and other permanent gases, and the C1-C2 hydrocarbons. A second PLOT column uses a divinylbenzene-ethylene glycol-dimethylacrylate porous polymer as stationary phase for the analysis of a wide range of C1-C2 organic molecules, Two complementary wall-coated open tubular (WCOT) columns with polydimethylsiloxane (PDMS) liquid stationary phases, one containing cyanopropyl-phenylsiloxane and the other diphenylsiloxane groups, are designed to target the same range of organic compounds (C3-C7) which could be representative of the widest range of cometary compounds. A third WCOT column with an apolar stationary phase made of non-substituted PDMS is used for the separation and identification of higher-molecular-mass compounds (up to C10) and aromatic species (monoaromatic and polyaromatic). This paper describes these five general-purpose capillary PLOT and WCOT columns, selected to be used in the COSAC GC system. The analytical capabilities are examined with a special emphasis on the exobiological and planetological implications.

Chromatography, Gas↗
PubMed2002

Third molar extraction. Current trends.

Extraction of third molars is the operation most frequently performed by oral and maxillofacial surgeons. The American National Institute of Health (1979) and the American Association of Oral and Maxillofacial Surgeons (1993) have organised consensus conferences to systematically analyse the scientific evidence and provide official guidelines for the management of third molars. However, some clinical aspects are still controversial: indications for preventive extraction, early extraction, prognosis of impacted teeth, continuous follow-up, relationship with anterior crowding and temporo-mandibular disorders. This article reviews the conclusions from the consensus conferences and integrates them with more recent data. The actual trend seems to justify a more conservative clinical approach rather than an aggressive extraction policy.

Adolescent↗
PubMed2001

Detection of martian amino acids by chemical derivatization coupled to gas chromatography: in situ and laboratory analysis.

If there is, or ever was, life in our solar system beyond the Earth, Mars is the most likely place to search for. Future space missions will have then to take into account the detection of prebiotic molecules or molecules of biological significance such as amino acids. Techniques of analysis used for returned samples have to be very sensitive and avoid any chemical or biological contamination whereas in situ techniques have to be automated, fast and low energy consuming. Several possible methods could be used for in situ amino acid analyses on Mars, but gas chromatography would likely be the most suitable. Returned samples could be analyzed by any method in routine laboratory use such as gas chromatography, already successfully performed for analyses of organic matter including amino acids from martian meteorites. The derivatization step, which volatilizes amino acids to perform both in situ and laboratory analysis by gas chromatography, is discussed here.

Amino Acids↗
PubMed2000

Gas chromatography for in situ analysis of a cometary nucleus. II. Analysis of permanent gases and light hydrocarbons with a carbon molecular sieve porous layer open tubular column.

Considering the severe constraints of space instrumentation, a great improvement for the in situ gas chromatographic (GC) determination of permanent and noble gases in a cometary nucleus is the use of a new carbon molecular sieve porous layer open tubular (PLOT) column called Carbobond. No exhaustive data dealing with this column being available, studies were carried out to entirely characterize its analytical performances, especially when used under the operating conditions of the cometary sampling and composition (COSAC) experiment of the European Space Agency (ESA) Rosetta space mission to be launched in 2003 for a rendezvous with comet 46 P/Wirtanen in 2011. The high efficiency and speed of analysis of this column at both atmospheric and vacuum outlet column pressure is demonstrated, and the kinetic mass transfer contribution of this carbon molecular sieve adsorbent is calculated. Besides, differential adsorption enthalpies of several gases and light hydrocarbons were determined from the variation of retention volume with temperature. The data indicate close adsorption behaviors on the Carbobond porous layer adsorbent and on the carbon molecular sieve Carboxen support used to prepare the packed columns. Moreover, taking into account the in situ operating conditions of the experiment, a study of two columns with different porous layer thicknesses allowed one to optimize the separation of the target components and to select the column parameters compatible with the instrument constraints. Comparison with columns of similar selectivity shows that these capillary columns are the first ones able to perform the same work as the packed and micro-packed columns dedicated to the separation of this range of compounds in GC space exploration.

Adsorption↗
PubMed1999

Gas chromatography for in situ analysis of a cometary nucleus: characterization and optimization of diphenyl/dimethylpolysiloxane stationary phases.

The development of a gas chromatograph for the cometary sampling and composition (COSAC) experiment is described in the context of the preparation for the European Space Agency (ESA) Mission Rosetta for investigation of a cometary nucleus. COSAC is one out of ten experiments on the Rosetta Lander. Its scientific goal is to analyze in situ the chemical composition of the volatile constituents of the nucleus of the target comet P/Wirtanen. Constituted of several (up to eight) capillary wall-coated and porous-layer open tubular columns operating in parallel, the GC system is designed to separate and identify both organic and inorganic compounds which evolve from the comet naturally or are obtained from cometary samples through stepwise heating in a miniaturized pyrolizer. In this first part of our study, dimethylpolysiloxane (DMPS) stationary phases with increasing percentages of diphenyl substituted group (DP) have been investigated. A coupled experimental and theoretical approach has been taken in order to predict chromatographic data. By the use of a four-point experimental calibration (0 to 65% diphenyl group) in conjunction with Pro ezGC modeling software, results in prediction of multicomponent chromatograms with a mean error less than 5% for each compound retention time were obtained, irrespective of the stationary phase's diphenyl content and column physical parameters. The possibility to associate such phases is illustrated by the evolution of coelutions obtained on a non-polar (100% DMPS) and a medium polar (65% DP-DMPS) stationary phase, respectively. This study showed that with a small number of well tuned DP-DMPS columns, the separation and identification of most of the targeted compounds can be achieved with a minimum amount of coelutions and within the experiment requirements.

Alcohols↗
PubMed1999

[The chin hole. Position and correlation with other mandibular parameters].

BACKGROUND: The present study analyzes the position of mental foramen, in order to research possible correlations with other mandibular parameters. METHODS: The study has been conducted on 76 dry mandibles, for each mandible we have measured the exact position of the mental forum respect the other mandibular parameters. Both linear and angular relations and misurations have been made. RESULTS AND CONCLUSIONS: The results obtained confirm that the mental foramen maintains its position by increasing GoGn. The results did not show particularly significant aspects in comparison with the literature on the subject, thus confirming other authors' opinion.

Adolescent↗
PubMed1999

[Surgical wound healing in oral surgery].

BACKGROUND: Aim of this study is to improve the in vivo knowledge about the real effects and the physiologic repair by a detached stitches silk suture in the 8th zone. METHODS: The study has been carried out on 44 patients submitted to surgical extraction of the impacted 8th (19 upper and 25 lower) teeth. RESULTS: Clinical and histological controls have demonstrated the usefulness of this suture procedure, since it gives a good histological reaction and in easy and safe. CONCLUSIONS: Histological and clinical results have confirmed the usefulness of silk suture, presenting however the inconvenience of stitches removal and bacterial plaque on the surgical wound.

Adolescent↗
PubMed1999

[Orodental management in patients with malignant hematologic diseases who are waiting for bone marrow transplantation].

BACKGROUND: This study aims to identify the main oral lesions caused by the use of chemotherapeutic agents pre- and post-transplant in malignant hemopathologies and to highlight the importance of dental prevention during this treatment in order to reduce and, if possible, avoid the resulting local and systemic complications. METHODS: Twenty-five patients were controlled, monitored and prepared to undergo the necessary chemo- and radiotherapy, as well as bone marrow transplantation in the majority of cases under the best possible oral conditions. RESULTS: The most commonly detected secondary lesions were reactions to cyclophosphamide and/or methotrexate. In general, this mucositis appeared 5-7 days after treatment and continued for 1-2 weeks before regressing without residue. Another post-radiotherapeutic complication observed was xerostomy. CONCLUSIONS: Lastly, it is important to underline that patients receiving correct dental infection preventive treatment showed fewer tertiary lesions than those who did not undergo the same procedure.

Adult↗
PubMed1999

[New suture techniques in oral surgery. Description and comparison with traditional sutures].

The study aimed to evaluate the healing of intraoral surgical wounds sutured with alpha-cyanoacrylate and silk in clinical and histological terms. Forty-four patients were checked 7 and 14 days after surgery. An incisional biopsy was made at the level of the discharge cut and histological tests were performed on the fragment. On the basis of the results, the authors affirm that in some areas (upper eighths), alpha-cyanoacrylate plays a useful role and simplifies the suture technique. On the contrary, this material was not sufficiently reliable in areas subject to excessive traction (lower eighths).

Adolescent↗
PubMed1998

The latest in ultrasound: three-dimensional imaging. Part II.

INTRODUCTION: The three-dimensional (3D) reconstruction of ultrasound images has become a widespread option in ultrasound equipment. Specific softwares have become available and 3D reconstruction feasible since the early 1990s, particularly since 1994. POSSIBLE CLINICAL APPLICATIONS: Several clinical applications are feasible in all parenchymatous organs (mainly the liver and prostate), hollow viscera (e.g. the bladder and gallbladder), peripheral vessels (supra-aortic trunks and limb vessels) and central (the aorta and iliac arteries) or cerebral vessels. Moreover, tumoral vessels in parenchymatous organs can be reconstructed, and even the fetus in the uterine cavity, with excellent detailing. The recent introduction of echocontrast agents and second harmonic imaging has permitted to study normal and abnormal peripheral, central and parenchymatous vessels, with similar patterns to those obtained with digital angiography. The spatial relationships between the vascular structures of the liver, kidney and placenta were studied with 3D ultrasound angiograms. The applications of this new technique include the analysis of vascular anatomy and the potential assessment of organ perfusion. THE LATEST APPLICATIONS--INTRAVASCULAR STUDIES: Some catheters with an ultrasound transducer in the tip have been tested for intravascular studies. Just like conventional transducers, they provide two-dimensional (2D) images which are then postprocessed into longitudinal 3D or volume reconstructions. The former resemble angiographic images and can be viewed 3D rotating the image along its longitudinal axis. Volume images, which are more complex and slower to obtain, can be rotated on any spatial plane and provide rich detailing of the internal vascular lumen. The clinical importance of intravascular ultrasound with 3D volume reconstructions lies in the diagnosis of vascular conditions and the assessment and monitoring of intravascular interventional procedures--e.g. to detect inaccurate deployment of intravascular stents and endoluminal grafts during the maneuver. Three-dimensional reconstructions involve geometric data assembly and volumetric interpolation of a spatially related sequence of tomographic cross sections generated by an ultrasound catheter withdrawn at a constant rate through a vascular segment of interest, resulting in the display of a straight segment. Therefore particular care is needed and there are some useful hints to avoid mistakes. CONCLUSIONS: Three dimensional reconstructions of B-mode and color Doppler images are no longer a work in progress and their clinical importance and possible applications are both established and ever-increasing. On the other hand, independent of the different types of energy used, also computed tomography and magnetic resonance 3D reconstructions are very useful from a clinical viewpoint and they have become an established routine technique for both these methods. It is very likely that 3D volume reconstructions in ultrasound will find numerous applications in the near future. They may help to increase the diagnostic confidence and to facilitate diagnosis, intraprocedure monitoring in interventional radiology and follow-up and also to reduce the number of invasive examinations with iodinated contrast agents. This could result in cutting the cost and duration of the most expensive examinations. New, although invasive, applications can be hypothesized for intravascular or intraluminal catheters with an ultrasound transducer inside.

Blood Vessels↗
PubMed1998

Review and latest results of laboratory investigations of Titan's aerosols.

Titan, the largest satellite of Saturn, has an atmosphere chiefly made up of N2 and CH4, and including many organics. This atmosphere also partly consists of hazes and aerosol particles which shroud the surface of this satellite, giving it a reddish appearance. The aerosols observed in Titan's atmosphere are thought to be synthesized at high altitudes (>300 km) and fall to the surface. Varying with temperature profiles, condensation phenomena take place in the lower atmosphere, about 100 km below. These solid particles, often called 'tholins', have been currently investigated for many years by laboratory scientists and physics modellers. This paper assesses past research and results in different fields (elemental composition, optical constants, pyrolysis, particle size), hightlighting interests and questions aroused by these studies. It also presents the latest results and advances, and concludes with existing problems and future pathways.

Aerosols↗
PubMed1997

Clinical usefulness of CT in the treatment of stage I endometrial carcinoma.

This retrospective study was aimed at assessing Computed Tomography (CT) capabilities in identifying low- and high-risk groups of clinical stage I endometrial carcinoma patients. CT of the pelvis was performed on 125 endometrial carcinoma patients who were divided into two groups based on T (stage and depth of myometrial invasion) and N (lymph node status) parameters. All patients had histologic evidence of well/moderately-differentiated adenocarcinoma (G1-G2). The low-risk group consisted of stage I patients with superficial myometrial involvement and no lymphadenopathy, while the high-risk group consisted of the patients with deep myometrial invasion and/or stage II and/or positive lymph nodes. All patients were operated on-i.e., total abdominal hysterectomy with vaginal cuff, bilateral salpingo-oophorectomy and pelvic lymphadenectomy. The patients were followed-up for 36 months at least. On the basis of CT findings, 85 patients were included in the low-risk group, but 11 misstaged cases were found at surgery in which lymphadenectomy never changed the factor risk. Only four relapses (4.7%) were observed in this group. Forty patients were included in the high-risk group: CT misstaged 20 cases and 12 relapses (30%) were observed. This study demonstrates the clinical value of CT in the assessment of radiologic risk factors in stage I endometrial carcinoma; CT findings can be used as guidelines for different treatments.

Adenocarcinoma↗
PubMed1995

Organic chemistry in Titan's atmosphere: new data from laboratory simulations at low temperature.

Many experiments have already been carried out to simulate organic chemistry on Titan, the largest satellite of Saturn. They can provide fruitful information on the nature of minor organic constituents likely to be present in Titan's atmosphere, both in gas and aerosol phases. Indeed, all the organic compounds but one already detected in Titan's atmosphere have been identified in simulation experiments. The exception, C4N2, as well as other compounds expected in Titan from theoretical modeling, such as other N-organics, and polyynes, first of all C6H2, have never been detected in experimental simulation thus far. All these compounds are thermally unstable, and the temperature conditions used during the simulation experiments were not appropriate. We have recently started a new program of simulation experiments with temperature conditions close to that of Titan's environment. It also uses dedicated analytical techniques and procedures compatible with the analysis of organics only stable at low temperatures, as well solid products of low stability in the presence of O2 and H2O. Spark discharge of N2-CH4 gas mixtures was carried out at low temperature in the range 100-150 K. Products were analysed by FTIR, GC and GC-MS techniques. GC-peaks were identified by their mass spectrum, and, in most cases, by comparison of the retention time and mass spectrum with standard ones. We report here the first detection in Titan simulation experiments of C6H2 and HC5N. Their abundance is a few percent relative to C4H2 and HC3N, respectively. Preliminary data on the solid products indicate an elemental composition corresponding to (H11C11N)n. These results open new prospects in the modeling of Titan's haze making.

Acetylene↗
PubMed1989

[The correlation between dental pathology and ophthalmic pathology].

The study aims to assess the correlation between dental pathologies and ophthalmic diseases. Based on a statistical evaluation, the study examines the presence of dental diseases in patients suffering from optic neuritis or uveitis in comparison to a control group of subjects. The possible interactions between the two ophthalmic pathologies and dental diseases are then analyzed in order to highlight possible clinical signs which may be useful for their identification.

Adolescent↗