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J Charlier

Publications and source records attributed to J Charlier.

At least 19 recordsLinked to original sources
PubMed2003

Evidence of the key role of metal-molecule bonding in metal-molecule-metal transport experiments.

The transport properties of two oligothiophene derivatives, that differ only by the chemical group coupling to gold, are compared. It is shown that the role of the coupling group in the transport properties can be decoupled from that of the conjugated body of the molecules and that Se is a better electronic coupling group than S. These results are accounted for semiquantitatively within the frame of the scattering theory of transport, using results from ultraviolet photoemission spectroscopy experiments as inputs for the position in energy of the molecular orbitals with respect to the Fermi level of the electrodes.

Journal Article↗
PubMed2001

Brevibacterium paucivorans sp. nov., from human clinical specimens.

Seven isolates from various human body sites displayed general chemotaxonomic and phenotypic characteristics of the genus Brevibacterium. This was corroborated by the 16S rRNA gene sequence analysis of strain CF62T, showing a sequence similarity of 99% to Brevibacterium mcbrellneri. However, DNA-DNA hybridization, a peculiar amino acid content of the cell wall and some phenotypic properties clearly suggested that these strains belong to a new species, for which the name Brevibacterium paucivorans sp. nov. is proposed. The type strain of B. paucivorans is CF62T (= DSM 13657T = LMG 19814T). The DNA G+C content of the type strain is 55.8 mol%.

Brevibacterium↗
PubMed2001

Optokinetic nystagmus in patients with central scotomas in age related macular degeneration.

BACKGROUND: Reports on the impact of a loss in the central field of vision on optokinetic nystagmus (OKN) are varied. A study was therefore undertaken to reassess the role of the central retina in the generation of OKN in a large group of patients with age related macular degeneration. METHODS: Four groups of 20 patients were examined: a control group without scotoma and three groups with absolute central scotomas measuring 1 degrees--10 degrees, 11 degrees--20 degrees, and 21 degrees--30 degrees. OKN was elicited with black and white stripes moving nasally to temporally or temporally to nasally on a screen subtending 54 degrees x 41 degrees at four velocities (15, 30, 45, and 60 degrees /s). OKN gain was measured using infrared oculography. RESULTS: There was no significant difference in OKN gain between the control group and those with scotomas of 1 degrees--10 degrees and 11 degrees--20 degrees. A significant difference in OKN gain was found between the group with scotomas of 21 degrees--30 degrees and all other groups at stimulus velocities of 30, 45, and 60 degrees/s (p<0.05). OKN gain significantly diminished with increasing stimulus velocity (p<0.05). No statistically significant difference was found in OKN gain between stimuli moving temporally to nasally and nasally to temporally. CONCLUSION: Abnormalities of OKN gain were noted only in patients with large scotomas. An intact macula is therefore not necessary for the generation of OKN.

Aged↗
PubMed2000

Dangling bond defects at Si-SiO2 interfaces: atomic structure of the P(b1) center

Using a first-principles approach, we characterize dangling bond defects at Si-SiO2 interfaces by calculating hyperfine parameters for several relaxed structures. Interface models, in which defect Si atoms remain close to crystalline sites of the substrate upon relaxation, successfully describe P(b) and P(b0) defects at (111) and (100) interfaces, respectively. On the basis of calculated hyperfine parameters, we discard models of the P(b1) defect containing a first neighbor shell with an O atom or a strained bond. A novel model consisting of an asymmetrically oxidized dimer yields hyperfine parameters in excellent agreement with experiment and is proposed as the structure of the P(b1) center.

Journal Article↗
PubMed2000

Coalescence of single-walled carbon nanotubes

The coalescence of single-walled nanotubes is studied in situ under electron irradiation at high temperature in a transmission electron microscope. The merging process is investigated at the atomic level, using tight-binding molecular dynamics and Monte Carlo simulations. Vacancies induce coalescence via a zipper-like mechanism, imposing a continuous reorganization of atoms on individual tube lattices along adjacent tubes. Other topological defects induce the polymerization of tubes. Coalescence seems to be restricted to tubes with the same chirality, explaining the low frequency of occurrence of this event.

Journal Article↗
PubMed2000

Dynamic behavior of nickel atoms in graphitic networks

The dynamic behavior of nickel atoms in graphitic carbon onions, observed by in situ atomic-resolution electron microscopy, shows the formation of stable new C-Ni phases. Nickel is observed to take substitutional in-plane positions in graphene layers, forming a planar graphitelike C-Ni lattice. Evidence is furthermore seen for the formation of a cubic C-Ni phase, suggesting a possible phase transformation in C-Ni from a graphitelike to a diamondlike structure. The stability of the planar phases is shown by first-principles calculations which also indicate that the C-Ni planes are metallic.

Journal Article↗
PubMed2000

Identification of Arthrobacter oxydans, Arthrobacter luteolus sp. nov., and Arthrobacter albus sp. nov., isolated from human clinical specimens.

Five Arthrobacter isolates from clinical specimens were studied by phenotypic, chemotaxonomic, and genetic characterization. Two strains had characteristics consistent with those of Arthrobacter oxydans. One strain was related to A. citreus; however, DNA-DNA hybridization and phenotypic characteristics indicated that this strain belongs to a new species, for which the name Arthrobacter luteolus sp. nov. is proposed. Two strains were closely related to A. cumminsii by 16S rRNA gene sequencing, but DNA-DNA hybridization, peptidoglycan type, and some phenotypic features indicated that they should be assigned to a new species, for which the name Arthrobacter albus sp. nov. is proposed. The type strain of A. luteolus is CF25 (DSM 13067). The type strain of A. albus is CF43 (DSM 13068).

Arthrobacter↗
PubMed1998

The development of visual pursuit during the first months of life.

BACKGROUND: There are few previous investigations of smooth pursuit in infants. The aim of our study was to quantify visual pursuit in infants between 1 day and 16 weeks of age. METHODS: Eye movements of 97 healthy infants between 1 day and 16 weeks of age were recorded one to seven times with infrared photo-oculography. For stimulation of visual pursuit a square of 9.4 deg of visual angle with vertical gratings moved horizontally at a constant velocity of 7.5 deg/s. RESULTS: In the first 2 weeks of life, segments of smooth pursuit were measured with a maximum velocity of 7.93 deg/s, with a maximum gain of 1.06 and a maximal duration of 3.16 s. In sequential recordings no significant increases of velocity, gain or duration were found. However, the total time the subjects followed the stimulus with smooth plus saccadic pursuit increased significantly with age (from a median of 39.0% to a median of 61.5% of examination time). CONCLUSION: This study clearly demonstrates that smooth pursuit is already present in the first week of life. We found no significant increase in velocity, gain and duration of smooth pursuit segments in the first 16 weeks of life with our recording technique. However, the total pursuit time, reflecting attention, increased with age. The ocular machinery to drive pursuit appears to be in place at birth and seems not to be influenced by increased attention in the first months of life.

Aging↗
PubMed1998

Surveillance of human Yersinia enterocolitica infections in Belgium: 1967-1996.

Between 1967 and 1996, > 18,700 strains of Yersinia species, excluding Yersinia pestis, were recovered in Belgium from a variety of gastrointestinal and extraintestinal sites in patients. Full identification and serotyping were performed by the two Belgian reference laboratories. Yersinia enterocolitica serogroup O:3 predominated (79.4% of strains), followed by serogroup O:9 (11.1%). The remaining 9.5% of isolates belonged to serogroups and related species generally considered nonpathogenic. Acute enterocolitis was the most common clinical form of Y. enterocolitica infection, affecting primarily children younger than 5 years of age. Since 1967, there was a steady increase in isolations every year, with 305 cases in 1975 and up to 1,469 in 1986. From 1987 on, there was a clear decrease in the number of reported cases, although the number of participating laboratories and culture techniques remained constant. This significant decrease in the occurrence of Y. enterocolitica infections may be explained by changes in the slaughtering procedures and eating habits of the population.

Adolescent↗