Co-doped Dy3+ and Pr3+ Ga5Ge20Sb10S65 fibers for mid-infrared broad emission.

Rare earth ion doped materials are means to obtain cost-effective infrared light sources, with enough brilliance for applications such as gas sensing. Within a sulfide matrix, the simultaneous luminescence of both Pr3+ and Dy3+ in the Ga5Ge20Sb10S65 glass is reported. The use of these two rare earths is giving rise to a broad continuous luminescence in the 2.2-5.5 µm wavelength range, which could be used as a mid-infrared light source for gas-sensing applications. The demonstration of CO2 and CH4 detection using a fiber drawn from these materials is reported.

Experimental design approach for deposition optimization of RF sputtered chalcogenide thin films devoted to environmental optical sensors.

The development of the optical bio-chemical sensing technology is an extremely important scientific and technological issue for diagnosis and monitoring of diseases, control of industrial processes, environmental detection of air and water pollutants. Owing to their distinctive features, chalcogenide amorphous thin films represent a keystone in the manufacture of middle infrared integrated optical devices for a sensitive detection of biological or environmental variations. Since the chalcogenide thin films characteristics, i.e. stoichiometric conformity, structure, roughness or optical properties can be affected by the growth process, the choice and control of the deposition method is crucial. An approach based on the experimental design is undoubtedly a way to be explored allowing fast optimization of chalcogenide film deposition by means of radio frequency sputtering process. Argon (Ar) pressure, working power and deposition time were selected as potentially the most influential factors among all possible. The experimental design analysis confirms the great influence of the Ar pressure on studied responses: chemical composition, refractive index in near-IR (1.55 µm) and middle infrared (6.3 and 7.7 µm), band-gap energy, deposition rate and surface roughness. Depending on the intended application and therefore desired thin film characteristics, mappings of the experimental design meaningfully help to select suitable deposition parameters.

Free-Volume Nanostructurization in Ga-Modified As2Se3 Glass.

Different stages of intrinsic nanostructurization related to evolution of free-volume voids, including phase separation, crystalline nuclei precipitation, and growth, were studied in glassy As2Se3 doped with Ga up to 5 at. %, using complementary techniques of positron annihilation lifetime spectroscopy, X-ray powder diffraction, and scanning electron microscopy with energy-dispersive X-ray analysis. Positron lifetime spectra reconstructed in terms of a two-state trapping model testified in favor of a native void structure of g-As2Se3 modified by Ga additions. Under small Ga content (below 3 at. %), the positron trapping in glassy alloys was dominated by voids associated with bond-free solid angles of bridging As2Se4/2 units. This void agglomeration trend was changed on fragmentation with further Ga doping due to crystalline Ga2Se3 nuclei precipitation and growth, these changes being activated by employing free volume from just attached As-rich glassy matrix with higher content of As2Se4/2 clusters. Respectively, the positron trapping on free-volume voids related to pyramidal AsSe3/2 units (like in parent As2Se3 glass) was in obvious preference in such glassy crystalline alloys.

Study of Ga incorporation in glassy arsenic selenides by high-resolution XPS and EXAFS.

Effect of Ga addition on the structure of vitreous As2Se3 is studied using high-resolution X-ray photoelectron spectroscopy and extended X-ray absorption fine structure techniques. The "8-N" rule is shown to be violated for Ga atoms and, possibly, for certain number of As atoms. On the contrary, Se keeps its 2-fold coordination according to "8-N" rule in the amorphous phase throughout all the compositions. Crystalline inclusions appear in the amorphous structure of the investigated glasses at Ga concentrations greater than 3 at. %. These inclusions are presumably associated with Ga2Se3 crystallites and transition phases/defects formed at the boundaries of these crystallites and host amorphous matrix. The existence of Ga-As and Se-Se bonds in the samples with higher Ga content is supported by present studies.

Wavelength conversion in Er(3+) doped chalcogenide fibers for optical gas sensors.

We report for the first time the conversion of incoherent infrared light around 4.4µm into a near-infrared signal at 810nm in erbium-doped GaGeSbS fibers and bulk glass samples. This energy conversion is made possible by pumping erbium doped chalcogenide samples at 982 nm and simultaneously exciting them with a 4.4µm infrared signal. This result paves the way for the development of an "all-optical" gas sensor able to detect various gas traces using a remote detection based on commercial silica fibers.

Structural evolution of Ga-Ge-Te glasses by combined EXAFS and XPS analysis.

The structural evolution of GaxGeyTe100-x-y glasses in the vicinity of GeTe4-GaTe3 pseudo-binary tie-line is determined with high-resolution X-ray photoelectron (XPS) and extended X-ray absorption fine structure (EXAFS) spectroscopies. The analysis of XPS data is complicated by similar electronegativity values for the constituent chemical elements, but then the interpretation is facilitated by information from complementary EXAFS analysis of the structure around each element independently. The results show 4∕4∕2 coordination for Ga∕Ge∕Te atoms and absence of Ga(Ge)-Ge(Ga) bonds or extended Te clusters in significant concentrations within the whole range of studied composition. The observed structural features correlate well with the measured basic physical properties of Ga-containing germanium telluride glasses.

77Se solid-state NMR investigations on As(x)Se(1-x) glasses using CPMG acquisition under MAS.

(77)Se (I=1/2) solid-state NMR is a very sensitive probe of the local structure of selenide glasses, which themselves are promising for optical applications. In this work, we show that although (77)Se has a low natural abundance (7.58%) and a wide spectral range, the sensitivity can be dramatically increased using Carr-Purcell-Meiboom-Gill (CPMG) trains of rotor-synchronized π pulses during the detection of (77)Se magnetization but may be affected by chemical shift anisotropy when the Magic Angle Spinning rate is not fast enough and by offset effects. The indirect dimension of the T(2)(CPMG)-resolved spectrum shows a strong influence of the J-couplings between naturally occurring (77)Se pairs. The resulting spectra show that the structural model known as "chains crossing model" is not entirely suitable to describe the glassy network of the Se-rich compositions.

Apatite forming ability and cytocompatibility of pure and Zn-doped bioactive glasses.

The use of bone grafts permits the filling of a bone defect without risk of virus transmission. In this work, pure bioactive glass (46S6) and zinc-doped bioactive glass (46S6Zn10) with 0.1 wt% zinc are used to elaborate highly bioactive materials by melting and rapid quenching. Cylinders of both types of glasses were soaked in a simulated body fluid (SBF) solution with the aim of determining the effect of zinc addition as a trace element on the chemical reactivity and bioactivity of glass. Several physico-chemical characterization methods such as x-ray diffraction, Fourier transform infrared spectroscopy and nuclear magnetic resonance methods, with particular focus on the latter, were chosen to investigate the fine structural behaviour of pure and Zn-doped bioactive glasses as a function of the soaking time of immersion in SBF. Inductively coupled plasma-optical emission spectroscopy (ICP-OES) was used to measure the concentrations of Ca and P ions in the SBF solution after different durations of immersion. The effect of the investigated samples on the proliferation rate of human osteoblast cells was assessed by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay, and tested on two different sizes of pure and zinc-doped glasses in powder form, with particle sizes that ranged between 40 to 63 µm and 500 to 600 µm. The obtained results showed the delay release of ions by Zn-doped glass (46S6Zn10) and the slower CaP deposition. Cytotoxicity and cell viability were affected by the particle size of the glass. The release rate of ions was found to influence the cell viability.

Infrared single mode chalcogenide glass fiber for space.

An important measuring technique under study for the DARWIN planet finding mission, is nulling interferometry, enabling the detection of the weak infrared emission lines of an orbiting planet. This technique requires a perfect wavefront of the light beams to be combined in the interferometer. By using a single mode waveguide before detection, wavefront errors are filtered and a virtually perfect plane wavefront is obtained. In this paper the results on the development and the optical characterisation of suitable infrared transmitting chalcogenide glasses and mid-IR guiding optical fibers are reported. Two different perform techniques for manufacturing core-cladding chalcogenide fibers are described. Two types of step index fibers, prepared with Te(2)As(3)Se(5) chalcogenide glasses, offer single mode guidance at 10.6 mum.

Metabolic imaging of tissues by infrared fiber-optic spectroscopy: an efficient tool for medical diagnosis.

Infrared fingerprints of molecules in biology contain much information on cells metabolism allowing one to distinguish between healthy and altered tissues. Here, to collect infrared signatures, we used evanescent wave spectroscopy based on an original infrared transmitting tapered glass fiber. A strict control of the fiber diameter in the tapered sensing zone allows high sensitivity and wide spectral range exploration from 800 to 3000 cm(-1). Then, merely in depositing the mouse liver biopsies on the fiber, this device has enable us to differentiate between tumorous and healthy tissues.

In situ sensing of volatile organic compounds in groundwater: first field tests of a mid-infrared fiber-optic sensing system.

A prototype mid-infrared sensor system for the determination of volatile organic pollutants in groundwater was developed and tested under real-world conditions. The sensor comprises a portable Fourier transform infrared spectrometer, coupled to the sensor head via mid-infrared transparent silver halide fiber-optic cables. A 10 cm unclad middle section of the 6-m-long fiber is coated with ethylene propylene copolymer in order to enrich the analytes within the penetration depth of the evanescent field protruding from the fiber sensor head. A mixture of tetrachloroethylene, dichlorobenzene, diethyl phthalate, and xylene isomers at concentrations in the low ppm region was investigated qualitatively and quantitatively in an artificial aquifer system filled with Munich gravel. This simulated real-world site at a pilot scale enables in situ studies of the sensor response and spreading of the pollutants injected into the system with controlled groundwater flow. The sensor head was immersed into a monitoring well of the aquifer system at a distance of 1 m downstream of the sample inlet and at a depth of 30 cm. Within one hour, the analytes were clearly identified in the fingerprint region of the IR spectrum (1300 to 700 cm(-1)). The results have been validated by head-space gas chromatography, using samples collected during the field measurement. Five out of six analytes could be discriminated simultaneously; for two of the analytes the quantitative results are in agreement with the reference analysis.

Body image perception among men in three countries.

OBJECTIVE: The authors tested the hypothesis that men in modern Western societies would desire to have a much leaner and more muscular body than the body they actually had or perceived themselves to have. METHOD: The height, weight, and body fat of college-aged men in Austria (N=54), France (N=65), and the United States (N=81) were measured. Using the somatomorphic matrix, a computerized test devised by the authors, the men chose the body image that they felt represented 1) their own body, 2) the body they ideally would like to have, 3) the body of an average man of their age, and 4) the male body they believed was preferred by women. The men's actual fat and muscularity was compared with that of the four images chosen. RESULTS: Only slight demographic and physical differences were found among the three groups of men. Modest differences were found between the men's measured fat and the fat of the images chosen. However, measures of muscularity produced large and highly significant differences. In all three countries, men chose a ideal body that was a mean of about 28 lb (13 kg) more muscular than themselves and estimated that women preferred a male body about 30 lb (14 kg) more muscular than themselves. In a pilot study, however, the authors found that actual women preferred an ordinary male body without added muscle. CONCLUSIONS: The wide discrepancy between men's actual muscularity and their body ideals may help explain the apparent rise in disorders such as muscle dysmorphia and anabolic steroid abuse.

From crystalline to glassy gallium fluoride materials: an NMR study of 69Ga and 71Ga quadrupolar nuclei.

Owing to the implementation of acquisition techniques specific for nuclei with very large quadrupolar interaction (full shifted echo and variable offset cumulative spectra (VOCS)), NMR spectra of 69Ga and 71Ga are obtained in crystallised (PbGaF5, Pb3Ga2F12, Pb9Ga2F24 and CsZnGaF6) and glassy (PbF2-ZnF2-GaF3) gallium fluorides. Simulations of both static (full echo or VOCS) and 15 kHz MAS spectra allow to obtain consistent determinations of isotropic chemical shifts and very large quadrupolar parameters (nu(Q) up to 14 MHz). In the crystalline compounds whose structures are unknown, the number and the local symmetry of the different gallium sites are tentatively worked out. For the glassy systems, a continuous Czjzek's distribution of the NMR quadrupolar parameters accounts for the particular shape of the NMR spectrum.

CP-MAS 207Pb with 19F decoupling NMR spectroscopy: medium range investigation in fluoride materials.

The isotropic chemical shift of 207Pb is used to perform structural investigations of crystalline fluoride compounds (PbF2, Pb2ZnF6, PbGaF5, Pb3Ga2F12 and Pb9Ga2F24) and transition metal fluoride glasses (TMFG) of the PZG family (PbF2-ZnF2-GaF3). Using 207Pb Cross Polarisation Magic Angle Spinning (CP-MAS) NMR with 19F decoupling, it is shown that the isotropic chemical shift of 207Pb varies on a large scale (1000 ppm) and that the main changes of its value are not due to the nearest neighbour fluorines but may be related to the number of next nearest neighbour (nnn) Pb2+ ions. In this way, it is demonstrated that 207Pb chemical shift is an interesting probe to investigate medium range order in either crystalline or glassy fluoride systems. The 207Pb delta(iso) parameter has been linearly correlated to the number of nnn Pb2+ ions.

From crystalline to glassy gallium fluoride materials: an NMR study of 69Ga and 71Ga quadrupolar nuclei.

Owing to the implementation of acquisition techniques specific for nuclei with very large quadrupolar interaction (full shifted echo and variable offset cumulative spectra (VOCS)), NMR spectra of 69Ga and 71Ga are obtained in crystallised (PbGaF5, Pb3Ga2F12, Pb9Ga2F24 and CsZnGaF6) and glassy (PbF2-ZnF2-GaF3) gallium fluorides. Simulations of both static (full echo or VOCS) and 15 kHz MAS spectra allow to obtain consistent determinations of isotropic chemical shifts and very large quadrupolar parameters (nuQ up to 14 MHz). In the crystalline compounds whose structures are unknown, the number and the local symmetry of the different gallium sites are tentatively worked out. For the glassy systems, a continuous Czjzek's distribution of the NMR quadrupolar parameters accounts for the particular shape of the NMR spectrum.

[Epstein-Barr virus research by in situ hybridization in 65 cutaneous T cell epidermotropic lymphomas]. / Recherche de l'Epstein-Barr virus par hybridation in situ chez 65 malades atteints de lymphomes cutanés T épidermotropes.

BACKGROUND: The Epstein-Barr virus (EBV) is a highly mutagenic virus known to be the cause of several types of lymphoma. There has been some controversy concerning EBV in cutaneous T-cell lymphomas. The aim of this study was to search for EBV with a sensitive method: in situ hybridization in 65 patients with cutaneous T-cell lymphomas. PATIENTS AND METHODS: From 1990 to 1995, 158 samples from 65 patients with cutaneous T-cell lymphoma (2 stage IA, 12 IB, 4 IIA, 29 IIB, 16 Sézary syndrome, 2 stage IV) were collected. In situ hybridization with EBER and Bam W probes recognizing the viral latency genes were used to search for EBV. RESULTS: EBV was evidenced with at least one of the two probes in 43 samples (26 p. 100). Prior to alpha interferon treatment, 18 p. 100 of the samples were positive for EBER compared with 18 p. 100 for Bam W. After alpha interferon treatment, there was a significantly higher percentage of EBER positive samples (39 p. 100; p = 0.03). Inversely, there was no difference for the Bam W probe (p = 0.2). Clinical stage had no effect on the presence of EBV (p = 0.18). CONCLUSION: Our series evidenced the variable presence of EBV, identified by in situ hybridization, in cutaneous T-cell lymphoma. Few infiltrating cells are infected. This would be an argument in favor of an indirect role of the EBV in the transformation process. In addition, alpha interferon increases the life time of EBERs, sensitizing detection of this latency gene.

Primary cutaneous lymphomas: a study of 37 cases.

BACKGROUND: A retrospective clinical, histologic, and immunohistochemical study was performed in 37 cases of isolated primary cutaneous lymphoma (PCL) (22 B and 15 T phenotype). Patients with epidermotrophic infiltrate (mycosis fungoides and Sézary syndrome) were excluded. METHODS: Patients with PCL were selected according to strict criteria: isolated cutaneous involvement for at least 6 months and a negative exhaustive study of possible spread. Lesions were either limited to a single cutaneous region or were disseminated, involving at least two nonadjacent regions. The diagnosis was confirmed histologically, and an immunohistochemical study was performed. RESULTS: On the basis of the new Willemze classification for prognostic criteria, this study showed similarities between lymphomas of B and T phenotype in clinical features, therapeutic response, course, and overall prognosis. The clinical lesion was usually an erythematous nodule associated, or not, with an infiltrated layer and generally limited to a single cutaneous region. PCLs were highly sensitive to nonaggressive treatment, showing complete or more than 50% partial remission in all cases. CONCLUSIONS: The overall prognosis for these lymphomas was good, even for disseminated cutaneous forms. Patient survival at 48 months was 78% for T and 89% for B phenotype. In the latter group, the prognosis was comparable for CD30+ and CD30- T lymphomas; however, the course of PCL involved frequent cutaneous relapses, particularly with the disseminated forms, raising the problem of adjuvant treatment after complete remission was obtained. Extracutaneous involvement was rare, but always indicative of poor prognosis.

Keratinocyte-lymphocyte interaction in cutaneous T-cell lymphoma. Modulation of keratinocyte antigen My7 by a soluble factor produced by T lymphocytes.

OBJECTIVE: To test the hypothesis that the modulation of My7 antigen in the basal keratinocytes is directly related to the effect of dermal lymphocyte infiltrate of epidermotropic cutaneous T-cell lymphoma (CTCL). DESIGN: In vitro study with reconstituted skin model. SETTING: Department of Dermatology of University Hospital, Nantes, France. PATIENTS: Lymphocytes extracted from 11 skin samples with lesions of epidermotropic CTCL (mycosis fungoides, stages IIa to IV) and 6 skin samples with lesions of atopic dermatitis (control population) together with the supernatants of these infiltrating lymphocytes were incubated with normal reconstituted skin samples either alone or in the presence of interferon alfa-2a (10(2) IU/ mL). Moreover, normal peripheral blood mononuclear cells of 7 patients and 4 controls were incubated with reconstituted skin. INTERVENTION: None MAIN OUTCOME MEASURES: None. RESULTS: Ten of 11 samples of lymphocytes extracted from CTCL and 7 of 11 of their supernatants inhibited partially or completely My7 expression by basal cells. NO inhibition was noted for lymphocytes extracted from inflammatory skin or their supernatants. Addition of interferon alfa-2a in a culture medium of extracted lymphocytes or their supernatants blocked inhibition of My7 expression by keratinocytes in 8 of 10 reconstituted skin samples. No abrogation of My7 expression was noted with peripheral mononuclear cells. CONCLUSIONS: Our in vitro study demonstrated a direct and specific interaction between the tumor infiltrate of CTCL and keratinocytes. Moreover, this interaction appeared to be closely associated with a soluble factor produced by the tumor T-cell infiltrate and was at least partially blocked by interferon alfa-2a.