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See detailHigh-resolution spectra of comet C/2013 R1 (Lovejoy)
Rousselot, P.; Decock, A.; Korsun, P. P. et al

in Astronomy and Astrophysics (2015), 580

Context. High-resolution spectra of comets permit deriving the physical properties of the coma. In the optical range, relative production rates can be computed, and information about isotopic ratios and ... [more ▼]

Context. High-resolution spectra of comets permit deriving the physical properties of the coma. In the optical range, relative production rates can be computed, and information about isotopic ratios and the origin of oxygen atoms can be obtained. <BR /> Aims: The main objective of the work presented here was to obtain information about the chemical composition of comet C/2013 R1 (Lovejoy), a bright and long-period comet that passed perihelion (0.81 au) on 22 December 2013. <BR /> Methods: We used the HARPS-North echelle spectrograph at the 3.5 m telescope TNG to obtain high-resolution spectra of comet C/2013 R1 (Lovejoy) in the optical range immediately after its perihelion passage during four consecutive nights in the period December 23 to 26, 2013. <BR /> Results: Our results demonstrate the ability of HARPS-North to efficiently obtain cometary spectra. Very faint emission lines, such as those of [SUP]15[/SUP]NH[SUB]2[/SUB], have been detected, leading to a rough estimate of the [SUP]14[/SUP]N/[SUP]15[/SUP]N ratio in NH[SUB]2[/SUB]. The [SUP]12[/SUP]C/[SUP]13[/SUP]C ratio was measured in the C[SUB]2[/SUB] lines and is equal to 80 ± 30. The oxygen lines were studied as well (green to red line intensity ratios and widths), confirming that H[SUB]2[/SUB]O is the main parent molecule that photodissociates to produce oxygen atoms. This suggests that this comet has a high CO[SUB]2[/SUB] abundance. Relative production rates for C[SUB]2[/SUB] and NH[SUB]2[/SUB] were computed, but we found no significant deviation from a typical NH[SUB]2[/SUB]/C[SUB]2[/SUB] ratio. Based on observations made with the Italian Telescopio Nazionale Galileo (TNG) operated on the island of La Palma by the Fundación Galileo Galilei of the INAF (Istituto Nazionale di Astrofisica) at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. [less ▲]

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See detailHigh-resolution spectra of comet C/2013 R1 (Lovejoy)
Rousselot, P.; Decock, A.; Jehin, Emmanuel ULiege et al

in Muinonen, Karri (Ed.) Asteroids, Comets, Meteors - Book of Abstracts (2014, July 01)

Comet C/2013 R1 (Lovejoy) is a long-period comet discovered on 7 September 2013 by Terry Lovejoy with a 0.2-m telescope (Guido et al., 2013), it passed its perihelion (0.81 au) on 22 December 2013. It was ... [more ▼]

Comet C/2013 R1 (Lovejoy) is a long-period comet discovered on 7 September 2013 by Terry Lovejoy with a 0.2-m telescope (Guido et al., 2013), it passed its perihelion (0.81 au) on 22 December 2013. It was a bright comet visible to the naked eye. We obtained high-resolution spectra of this comet immediately after its perihelion passage during 4 nights in the period 23-26 December 2013. These spectra have been obtained with the 3.5-m Telescopio Nazionale Galileo (TNG) and the High Accuracy Radial velocity Planet Searcher in North hemisphere (HARPS-N) echelle spectrograph. HARPS-N is an echelle spectrograph covering the spectral range from 383 to 693 nm, with a spectral resolution of R=115000 (Cosentino et al., 2012). It is designed to measure stellar radial velocities in view of detecting extrasolar planets. Our observations are the first successful cometary observations performed with this instrument. They demonstrate that this spectrograph can also be efficient for getting cometary spectra, even if the sensitivity of this instrument is low in the blue part of its spectral coverage. We will present the results of our data analysis for these spectra. This analysis is focused on isotopic ratios, mainly ^{12}C/^{13}C with C_2 emission lines (with the method described in Rousselot et al. 2012) and ^{14}N/^{15}N with ^{14}NH_2 and ^{15}NH_2 emission lines (with the line wavelengths given in Rousselot et al. 2014), atomic oxygen emission lines at 557.7, 630.0 and 636.4 nm (intensity ratios and widths, see Decock et al. 2013) and relative production rates of the detected species. [less ▲]

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See detailHIGH-RESOLUTION SPECTRA OF JUPITER NORTHERN AURORAL ULTRAVIOLET EMISSION WITH THE HUBBLE-SPACE-TELESCOPE
TRAFTON, L. M.; Gérard, Jean-Claude ULiege; Munhoven, Guy ULiege et al

in Astrophysical Journal (1994), 421(2), 816-827

The first spectroscopic observations of planetary aurora with the HST are reported. These include spectral regions centered on the H-2 Lyman and Werner bands of a region of Jupiter's northern aurora. The ... [more ▼]

The first spectroscopic observations of planetary aurora with the HST are reported. These include spectral regions centered on the H-2 Lyman and Werner bands of a region of Jupiter's northern aurora. The observations were made with the Goddard High Resolution Spectrograph (GHRS) using the Large Science Aperture as part of a campaign to study Jupiter at the time of the Ulysses flyby. The individual rotational-vibrational bands are resolved and the observed emissions are essentially all from H-2. A rotational-vibrational temperature for H-2 of 530 +/- 100 K is derived, a value significantly less than the 850-1100 K reported for Jovian H-3(+) in the near-infrared but consistent with the temperature reported for fundamental-band quadrupole H-2 emission. Comparison with the Faint Object Camera (FOC) images shows that the observed region was not one of the hot spots of the aurora. The results are interpreted in terms of electron impact excitation of H-2 from secondary particles generated by primaries precipitating into Jupiter's atmosphere from the magnetosphere. In the region of the aurora observed, the homopause level is found to be significantly hotter but not necessarily higher than observed at nonauroral latitudes. The equatorial H-2 dayglow spectrum was also detected; its intensity was 3.2 kR or 13% of the strength of the observed auroral emission. [less ▲]

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See detailHigh-resolution spectropolarimetric observations of hot subdwarfs
Petit, P.; Van Grootel, Valérie ULiege; Bagnulo, S. et al

in Leaflet - Astronomical Society of the Pacific (2012, March 01), 452

We report on high-resolution spectropolarimetric observations of the hot subdwarf stars HD 76431 and Feige 66, using the ESPaDOnS echelle spectropolarimeter at CFHT. We compute cross-correlation Stokes I ... [more ▼]

We report on high-resolution spectropolarimetric observations of the hot subdwarf stars HD 76431 and Feige 66, using the ESPaDOnS echelle spectropolarimeter at CFHT. We compute cross-correlation Stokes I and V line profiles to enhance the signal-to-noise ratio. We then average all available cross-correlation profiles of each star to further decrease the noise level. Although both targets were previously reported to host kilo-gauss magnetic fields, we do not derive any evidence of large-scale photospheric fields from our sets of observations, in spite of tight error bars on the longitudinal field of the order of 60 gauss for HD 76431 and 200 gauss for Feige 66. A new analysis of FORS1 observations of HD 76431, which provided the basis for the original claim of field detection, confirms the absence of any detectable Zeeman signature, with an error bar of about 100 gauss on the longitudinal magnetic field. [less ▲]

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See detailHigh-resolution spectroscopy of the C2 Swan 0-0 band from Comet P/Halley
Lambert, D. L.; Sheffer, Y.; Danks, A. C. et al

in Astrophysical Journal (1990), 353

High-resolution spectra of the C2 Swan system's 0-0 band from Comet P/Halley in March 1986 show that the populations of the upper state's rotational levels may be described by two rotational temperatures ... [more ▼]

High-resolution spectra of the C2 Swan system's 0-0 band from Comet P/Halley in March 1986 show that the populations of the upper state's rotational levels may be described by two rotational temperatures. The low rotational levels provide a low temperature, Trot = about 600 - 700 K. The higher levels correspond to about 3200 K. If a contribution from the 3200-K molecules is subtracted from the populations of the low-J-prime levels, the latter are characterized by Trot = about 190 K. A comparison with recent predictions for C2 molecules fluorescing in sunlight shows that the observed and predicted level populations are in good agreement for J-prime greater than about 15, but there is a sharp disagreement for the low rotational levels. [less ▲]

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See detailHigh-resolution X-ray microtomography to determine the kinetics of water vapour adsorption
Lodewyckx, Peter; Léonard, Angélique ULiege; Blacher, Silvia ULiege

Conference (2005, October)

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See detailHigh-resolution X-ray spectroscopy of the magnetic Of?p star HD148937
Nazé, Yaël ULiege; Zhekov, S. A.; Walborn, N. R.

in Astrophysical Journal (2012), 746

High-resolution data of the peculiar magnetic massive star HD148937 were obtained with Chandra-HETGS, and are presented here in combination with a re-analysis of the older XMM-RGS data. The lines of the ... [more ▼]

High-resolution data of the peculiar magnetic massive star HD148937 were obtained with Chandra-HETGS, and are presented here in combination with a re-analysis of the older XMM-RGS data. The lines of the high-Z elements (Mg, Si, S) were found to be unshifted and relatively narrow (FWHM of about 800km/s), i.e. narrower than the O line recorded by RGS, which possibly indicates that the hot plasma is multi-thermal and has several origins. These data further indicate a main plasma temperature of about 0.6keV and a formation of the X-ray emission at about one stellar radius above the photosphere. From the spectral fits and the H-to-He line ratios, the presence of very hot plasma is however confirmed, though with a smaller relative strength than for the prototype magnetic oblique rotator $\theta^1$\,Ori\,C. Both stars thus share many similarities, but HD148937 appears less extreme than $\theta^1$\,Ori\,C despite having also a large magnetic confinement parameter. [less ▲]

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See detailHigh-resolution X-ray spectroscopy of theta Carinae
Nazé, Yaël ULiege; Rauw, Grégor ULiege

in Astronomy and Astrophysics (2008), 490(2), 801-806

Context. The peculiar hot star. Car in the open cluster IC2602 is a blue straggler as well as a single-line binary with a short period (2.2d). Aims. Its high-energy properties are not well known, though X ... [more ▼]

Context. The peculiar hot star. Car in the open cluster IC2602 is a blue straggler as well as a single-line binary with a short period (2.2d). Aims. Its high-energy properties are not well known, though X-rays can provide useful constraints on the energetic processes at work in binaries as well as in peculiar, single objects. Methods. We present the analysis of a 50 ks exposure taken with the XMM-Newton observatory. It provides medium as well as high-resolution spectroscopy. Results. Our high-resolution spectroscopy analysis reveals a very soft spectrum with multiple temperature components (1-6 MK) and an X-ray flux slightly below the 'canonical' value (log [L-X(0.1-10.)/L-BOL]similar to -7). The X-ray lines appear surprisingly narrow and unshifted, reminiscent of those of beta Cru and tau Sco. Their relative intensities confirm the anomalous abundances detected in the optical domain (C strongly depleted, N strongly enriched, O slightly depleted). In addition, the X-ray data favor a slight depletion in neon and iron, but they are less conclusive for the magnesium abundance, which may be solar-like. While no significant changes occur during the XMM-Newton observation, variability in the X-ray domain is detected in the long-term range. The formation radius of the X-ray emission is loosely constrained to < 5 R-circle dot, which allows for a range of models (wind-shock, corona, magnetic confinement,...) though not all of them can be reconciled with the softness of the spectrum and the narrowness of the lines. [less ▲]

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See detailHigh-resolution X-ray structures of human apoferritin H-chain mutants correlated with their activity and metal-binding sites.
Toussaint, Louise ULiege

in Journal of Molecular Biology (2007), 365(2), 440-52

Ferritins are a family of proteins distributed widely in nature. In bacterial, plant, and animal cells, ferritin appears to serve as a soluble, bioavailable, and non-toxic form of iron provider. Ferritins ... [more ▼]

Ferritins are a family of proteins distributed widely in nature. In bacterial, plant, and animal cells, ferritin appears to serve as a soluble, bioavailable, and non-toxic form of iron provider. Ferritins from animal sources are heteropolymers composed of two types of subunit, H and L, which differ mainly by the presence (H) or absence (L) of active ferroxidase centres. We report the crystallographic structures of four human H apoferritin variants at a resolution of up to 1.5 Angstrom. Crystal derivatives using Zn(II) as redox-stable alternative for Fe(II), allows us to characterize the different metal-binding sites. The ferroxidase centre, which is composed of sites A and B, binds metal with a preference for the A site. In addition, distinct Zn(II)-binding sites were found in the 3-fold axes, 4-fold axes and on the cavity surface near the ferroxidase centre. To study the importance of the distance of the two metal atoms in the ferroxidase centre, single and double replacement of glutamate 27 (site A) and glutamate 107 (site B), the two axial ligands, by aspartate residues have been carried out. The consequences for metal binding and the correlation with Fe(II) oxidation rates are discussed. [less ▲]

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See detailHigh-Resolution, Human-Bovine Comparative Mapping Based on a Closed Yac Contig Spanning the Bovine Mh Locus
Pirottin, Dimitri ULiege; Poncelet, D.; Grobet, Luc ULiege et al

in Mammalian Genome : Official Journal of the International Mammalian Genome Society (1999), 10(3), 289-93

A closed YAC contig spanning the mh locus was assembled by STS content mapping with seven microsatellite markers, eight genes or EST, and nine STS corresponding to YAC ends. The contig comprises 27 YACs ... [more ▼]

A closed YAC contig spanning the mh locus was assembled by STS content mapping with seven microsatellite markers, eight genes or EST, and nine STS corresponding to YAC ends. The contig comprises 27 YACs, has an average depth of 4.3 YACs, and spans an estimated 1.2 Mb. A linkage map was constructed based on five of the microsatellite markers anchored to the contig and shown to span 7 cM, yielding a ratio of 160 kb/1 cM for the corresponding chromosome region. Comparative mapping data indicate that the constructed contig spans an evolutionary breakpoint connecting two chromosome segments that are syntenic but not adjacent in the human. Consolidation of human gene order by means of whole genome radiation hybrids and its comparison with the bovine order as inferred from the contig confirm conservation of gene order within segments. [less ▲]

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See detailHigh-risk HPV type-specific clearance rates in cervical screening.
Bulkmans, N. W. J.; Berkhof, J.; BULK, Saskia ULiege et al

in British journal of cancer (2007), 96(9), 1419-24

We assessed clearance rates of 14 high-risk human papillomavirus (hrHPV) types in hrHPV-positive women with normal cytology and borderline/mild dyskaryosis (BMD) in a population-based cervical screening ... [more ▼]

We assessed clearance rates of 14 high-risk human papillomavirus (hrHPV) types in hrHPV-positive women with normal cytology and borderline/mild dyskaryosis (BMD) in a population-based cervical screening cohort of 44,102 women. The 6-month hrHPV type-specific clearance rates, that is, clearance of the same type as detected at baseline, in women with normal and BMD smears were 43% (95% confidence interval (CI) 39-47) and 29% (95% CI 24-34), respectively. Corresponding 18-month clearance rates were markedly higher, namely 65% (95% CI 60-69) and 41% (95% CI 36-47), respectively. The lowest clearance rates in women with normal cytology were observed for HPV16, HPV18, HPV31, and HPV33. Significantly reduced 18-month clearance rates at a significance level of 1% were observed for HPV16 (49%, 95% CI 41-59) and HPV31 (50%, 95% CI 39-63) in women with normal cytology, and for HPV16 (19%, 95% CI 12-29) in women with BMD. Among women who did not clear hrHPV, women with HPV16 persistence displayed an increased detection rate of >or=CIN3 (normal P<0.0001; BMD, P=0.005). The type-specific differences in clearance rates indicate the potential value of hrHPV genotyping in screening programs. Our data support close surveillance (i.e. referral directly, or within 6 months) of women with HPV16 and are inconclusive for surveillance of women with HPV18, HPV31, and HPV33. For the other hrHPV-positive women, it seems advisable to adopt a conservative management with a long waiting period, as hrHPV clearance is markedly higher after 18 months than after 6 months and the risk for >or=CIN3 is low. [less ▲]

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See detailHigh-risk human papillomavirus infection of the genital tract of women with a previous history or current high-grade vulvar intraepithelial neoplasia
Goffin, Frédéric ULiege; Mayrand, Marie-Hélène; Gauthier, Philippe et al

in Journal of Medical Virology (2006), 78(6), 814-819

Human papillomavirus (HPV) infection is associated with high-grade vulvar intraepithelial neoplasia (VIN-3). The prevalence of anogenital HPV infection in women with previously treated VIN-3 has not been ... [more ▼]

Human papillomavirus (HPV) infection is associated with high-grade vulvar intraepithelial neoplasia (VIN-3). The prevalence of anogenital HPV infection in women with previously treated VIN-3 has not been documented yet. This cross-sectional study compared high-risk HPV DNA detection rates in women with past (n = 30) and current (n = 22) VIN-3 to those without current or past VIN (n = 86). HPV DNA was detected in vulvar and cervical samples with Hybrid Capture 2 (HC-2). Smoking was associated in multivariate analysis with current VIN-3 (odds ratio (OR) 8.3, 95% confidence interval (CI) 2.0-8.2) and any VIN-3 history (OR 6.5, 95% CI 2.5-16.5). High-risk HPV DNA was found on the vulva of 64%, 33%, and 20% of women with current VIN-3, past VIN-3, and without previous or current VIN, respectively. After controlling for age and smoking, high-risk HPV vulvar infection was associated with cervical high-risk HPV infection (OR 8.6, 95% CI 2.8-26.5; P = 0.001). After controlling for age, HPV infection was more often multifocal in women with current VIN-3 compared to women with previous but no current VIN-3 lesion (OR 17.6, 95% CI 1.4-227.2). Multifocal vulvar HPV infection was detected in women with previous or active VIN-3. Longitudinal studies are required to determine if the multifocality of HPV infection on the vulva could explain the high recurrence rate of VIN-3. [less ▲]

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See detailHigh-risk human papillomavirus is present in cytologically false-negative smears: an analysis of "normal" smears preceding CIN2/3.
BULK, Saskia ULiege; Rozendaal, L.; Zielinski, G. D. et al

in Journal of clinical pathology (2008), 61(3), 385-9

AIMS: Cervical screening, currently performed by cervical cytology, depends on the timely detection of malignant lesions for its success. The presence of high-risk human papillomavirus (hrHPV) is ... [more ▼]

AIMS: Cervical screening, currently performed by cervical cytology, depends on the timely detection of malignant lesions for its success. The presence of high-risk human papillomavirus (hrHPV) is associated with an increased risk of subsequent high-grade cervical intra-epithelial neoplasia (CIN2/3) and cervical cancer. The aim of this study was to determine the extent to which hrHPV is present in cervical smears with a high a priori chance of being false negative (ie, in normal smears preceding CIN2/3). METHODS: Archival specimens of 187 women with CIN2/3 and preceding normal conventional smears were identified retrospectively. Of these specimens, 144 (77%) had adequate cytological samples for further HPV DNA testing. RESULTS: Of 144 CIN2/3 lesions, preceding normal smears showed hrHPV positivity in 80% of cases. Of the hrHPV-positive smears, 69% were upgraded cytologically at rescreening compared with 24% of hrHPV-negative smears (p<0.001). Upgrading of smears was not associated with specific hrHPV types (p = 0.217). In over 90% of cases, type concordance in smear and CIN2/3 lesion was demonstrated. CONCLUSIONS: hrHPV is present in a high proportion of normal archival smears preceding CIN2/3, and false-negative cytology was highly associated with the presence of hrHPV. This supports the current notion that hrHPV testing can be used as a primary cervical screening tool. If so, hrHPV-positive cervical smears should be carefully examined for cytological abnormalities to reduce false-negative cervical cytology. [less ▲]

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See detailHigh-sensitivity staining of proteins for one- and two-dimensional gel electrophoresis using post migration covalent staining with a ruthenium fluorophore.
Tokarski, Caroline; Cren-Olive, Cecile; Fillet, Marianne ULiege et al

in Electrophoresis (2006), 27(7), 1407-16

This paper describes the use of a ruthenium complex ((bis(2,2'-bipyridine)-4'-methyl-4-carboxybipyridine-ruthenium-N-succidimyl ester-bis(hexafluorophosphate), abbreviated below as ASCQ_Ru) commercially ... [more ▼]

This paper describes the use of a ruthenium complex ((bis(2,2'-bipyridine)-4'-methyl-4-carboxybipyridine-ruthenium-N-succidimyl ester-bis(hexafluorophosphate), abbreviated below as ASCQ_Ru) commercially available and chemically pure. This new ruthenium complex ASCQ_Ru brings an activated ester, allowing the selective acylation of amino acid side chain amines for the post migration staining of proteins separated in 1-DE and 2-DE. The protocol used is a simple three-step protocol fixing the proteins in the gel, staining and then washing, as no lengthy destaining step is required. First the critical staining step was optimized. Although in solution the best described pH for acylating proteins with this reagent is phosphate buffer at pH 7.0, we found that best medium for in-gel staining is unbuffered ACN/water solution (20/80 v/v). The two other steps are less critical and classical conditions are satisfactory: fixing with 7% acetic acid/10% ethanol solution and washing four times for 10 min with water. Sensitivity tests were performed using 1-DE on protein molecular weight markers. We obtained a higher sensitivity than SYPRO Ruby with a detection limit of 80 pg of protein per well. However, contrary to SYPRO Ruby, ASCQ_Ru exhibits a logarithmic dependency on the amount of protein. The dynamic range is similar to SYPRO Ruby and is estimated between three and four orders of magnitude. Finally, the efficiency of the post migration ASCQ_Ru staining for 2-D gel separation is demonstrated on the whole protein extract from human colon carcinoma cells lines HCT 116. ASCQ_Ru gave the highest number of spot detected compared to other common stains Colloidal CBB, SYPRO Ruby and Deep Purple. [less ▲]

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See detailHigh-speed imaging use to predict spray retention on barley leaves
Boukhalfa, Hassina dite Hafida ULiege; Massinon, Mathieu ULiege; Lebeau, Frédéric ULiege

in Communications in Agricultural and Applied Biological Sciences (2013, May 21), Vol 78(2)(1-386 (2013)), 31-36

Laboratory studies were conducted to validate the effectiveness of the use of high-speed imaging method to replace chemical nalysis by fluoremetrie. Measurements were performed with a high-speed camera ... [more ▼]

Laboratory studies were conducted to validate the effectiveness of the use of high-speed imaging method to replace chemical nalysis by fluoremetrie. Measurements were performed with a high-speed camera coupled with a retro-LED lighting. Size and velocity of the drop were extracted by image analysis. Drop impact types were determined by the operator. Drops were produced with a flat-fan nozzle mounted on a movable ramp. Two surfactants (Break-Thru® S240 and Li700 ®) were sprayed on BBCH 12 barley leaves to highlight the effect of the reduction of surface tension. Relative volume proportions were computed within of an energy scale divided into 11 classes based on the Weber number. results are compared to the results of the chemical analysis by spectrofluerometry. [less ▲]

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See detailHigh-speed Photometric Observations of ZZ Ceti White Dwarf Candidates
Green, E.M.; Limoges, M.-M.; Gianninas, A. et al

in Astronomical Society of the Pacific Conference Series (2015, June), 493

We present high-speed photometric observations of ZZ Ceti white dwarf candidates drawn from the spectroscopic survey of bright DA stars from the Villanova White Dwarf Catalog by Gianninas et al., and from ... [more ▼]

We present high-speed photometric observations of ZZ Ceti white dwarf candidates drawn from the spectroscopic survey of bright DA stars from the Villanova White Dwarf Catalog by Gianninas et al., and from the recent spectroscopic survey of white dwarfs within 40 parsecs of the Sun by Limoges et al. We report the discovery of six new ZZ Ceti pulsators from these surveys, and several photometrically constant DA white dwarfs, which we then use to refine the location of the ZZ Ceti instability strip. [less ▲]

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See detailHigh-Technology Service Innovation Success: A Decision-Making Perspective
Van Riel, Allard ULiege; Lemmink, Jos; Ouwersloot, Hans

in Journal of Product Innovation Management (2004), 21(5), 348-359

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See detailHigh-temperature and quantitative XRD study of typical Westerwald clays (Germany)
Fontaine, François ULiege; Fagel, Nathalie ULiege

Poster (2016, July 05)

The Westerwald is one of the largest and oldest clay mining area of Germany. Those deposits were formed during the Eocene and Oligocene as a result of the weathering, erosion and redeposition of Devonian ... [more ▼]

The Westerwald is one of the largest and oldest clay mining area of Germany. Those deposits were formed during the Eocene and Oligocene as a result of the weathering, erosion and redeposition of Devonian rocks. During the Miocene, intense volcanic activities led to a large basalt cover, protecting the clays from the erosion. The fine fraction is mainly composed of kaolinite and illite, with the possible presence of interstratified I S. Other minerals such as quartz, feldspars, hematite, goethite or anatase are present in variable concentrations. Four typical Westerwald clays were chosen for this study: kaolinite-rich clay, kaolinite-illite clay, a red and a yellow firing clays. The first goal is to perform quantitative XRD using two different methods and to compare them: reference intensity ratio (RIR) and Rietveld (using Topas and BGMN). The second goal is the study of those samples using high-temperature XRD (HTXRD). The samples were heated up to 1250°C and a XRD pattern was obtained in situ every 100°C. The results show the temperatures of vitrification and formation of mullite and cristobalite varying from one sample to another, which is mainly linked to their flux concentration. [less ▲]

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See detailHigh-temperature polyimide nanofoams for microelectronic applications
Hedrick, James L; Carter, K. R.; Cha, J. E. et al

in Reactive & Functional Polymers (1996), 30(1-3), 43-53

Foamed polyimides have been developed in order to obtain thin film dielectric layers with very low dielectric constants for use in microelectronic devices. In these systems the pore sizes are in the ... [more ▼]

Foamed polyimides have been developed in order to obtain thin film dielectric layers with very low dielectric constants for use in microelectronic devices. In these systems the pore sizes are in the nanometer range, thus, the term 'nanofoam'. The polyimide foams are prepared from block copolymers consisting of thermally stable and thermally labile blocks, the latter being the dispersed phase. Foam formation is effected by thermolysis of the thermally labile block, leaving pores of the size and shape corresponding to the initial copolymer morphology. Nanofoams prepared from a number of polyimides as matrix materials were investigated as well as from a number of thermally labile polymers. The foams were characterized by a variety of experiments including TEM, SAXS, WAXD, DMTA, density measurements. refractive index measurements and dielectric constant measurements. Thin film foams, with high thermal stability and low dielectric constants approaching 2.0, can be prepared using the copolymer/nanofoam approach. [less ▲]

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