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  • Articles  (29)
  • BioMed Central  (11)
  • Oxford University Press  (10)
  • American Institute of Physics (AIP)  (8)
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  • Articles  (29)
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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 1128-1135 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Raman spectroscopy is used to investigate strong band bending at the interface in semi-insulating substrates of ZnSe/GaAs heterostructures grown at high epitaxy rates. Direct evidence is given of the enhancement of polar modes strength, on the substrate side, by the electric field of the space-charge zone associated with Fermi-level pinning. The latter is qualitatively analyzed by following band flattening under illumination through the evolution of interfacial coupled LO-phonon–plasmon modes. Corresponding Raman line shapes are discussed within the phenomenological approach of D. H. Hon and W. L. Faust [Appl. Phys. 1, 241 (1973)]. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 1241-1248 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Apparent p-type conductivity in nonintentionally doped ZnSe layers, grown at high temperature on semi-insulating GaAs substrates, is investigated by Raman spectroscopy. The microprobe technique provides direct evidence for carrier location on the GaAs side of the structures, close to the interface. Line-shape analysis of the coupled LO phonon-plasmon mode for different exciting wavelengths can be achieved, within the model of Hon and Faust [Appl. Phys. 1, 241 (1973)], only when incorporating plasma inhomogeneity. Electronic band bending at the junction in GaAs is deduced from the inferred carrier-density profile. Changes in Raman spectra under strong illumination are shown to proceed from the flattening of the bands through selective carrier photoinjection. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 63 (1993), S. 3236-3237 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 519-521 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Long wavelength longitudinal optical (LO) and transverse optical (TO) phonons of BeSe and ZnxBe1−xSe layers are identified in a wide composition range by using Raman spectroscopy. A two-mode behavior is clearly evidenced. As predicted by the dielectric model of Hon and Faust, the eigenfrequencies of the BeSe- and ZnSe-like LO modes correspond to the maxima of Im〈−cursive-epsilon(ω, x)−1〉. Excellent agreement is obtained with a model where the calculations are performed by using the equations of motion and polarization derived from the modified random element isodisplacement model. Besides, the TO and LO frequencies for BeSe are determined to be 501 and 579 cm−1, respectively. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 80 (2002), S. 3081-3083 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Zone-center longitudinal (LO) and transverse (TO) optical phonons of Zn1−xBexTe epilayers are identified by Raman spectroscopy. On top of the expected BeTe- and ZnTe-like modes, which obey the modified-random-element-isodisplacement model, we observe an extra BeTe-like (TO, LO) doublet at intermediate x values. It has the same atypical characteristics as its BeSe-like counterpart in ZnBeSe alloy. Its activation validates our percolative picture for multimode description in Be–chalcogenide alloys that open the attractive class of mixed crystals with a sharp contrast in the bond stiffness. Also, the local modes of Be in ZnTe and of Zn in BeTe are identified at 411 cm−1 and 195 cm−1, respectively. © 2002 American Institute of Physics.
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 2371-2376 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The activation of inhomogeneous electric field-induced Raman scattering (IEFIRS) at ZnSe/GaAs interfaces is investigated. The consideration of the inhomogeneous character of the electric field brings additional conditions on top of those predicted by the microscopic and perturbative approaches. These conditions concern the relative orientations of (i) the wave vector of the vibrational modes in the matter, (ii) the direction of the electric field at the junction, and (iii) the gradient vector of the electric field magnitude in the space charge regions. As latter vector has opposite directions in the layer and the substrate, IEFIRS is only observed from one side of the junction for a given scattering geometry. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 7
    Publication Date: 2013-04-17
    Description: Background: Deliberate cellular reprogramming is becoming a realistic objective in the clinic. While the origin of the target cells is critical, delivery of bioactive molecules to trigger a shift in cell-fate remains the major hurdle. To date, several strategies based either on non-integrative vectors, protein transfer or mRNA delivery have been investigated. In a recent study, a unique modification in the retroviral genome was shown to enable RNA transfer and its expression. Results: Here, we used the retroviral mRNA delivery approach to study the impact of modifying gene-flanking sequences on RNA transfer. We designed modified mRNAs for retroviral packaging and used the quantitative luciferase assay to compare mRNA expression following viral transduction of cells. Cloning the untranslated regions of the vimentin or non-muscular myosin heavy chain within transcripts improved expression and stability of the reporter gene while slightly modifying reporter-RNA retroviral delivery. We also observed that while the modified retroviral platform was the most effective for retroviral mRNA packaging, the highest expression in target cells was achieved by the addition of a non-viral UTR to mRNAs containing the packaging signal. Conclusions: Through molecular engineering we have assayed a series of constructs to improve retroviral mRNA transfer. We showed that an authentic RNA retroviral genomic platform was most efficiently transferred but that adding UTR sequences from highly expressed genes could improve expression upon transfection while having only a slight effect on expression from transferred RNA. Together, these data should contribute to the optimisation of retroviral mRNA-delivery systems that test combinations of UTRs and packaging platforms.
    Electronic ISSN: 1472-6750
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Published by BioMed Central
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  • 8
    Publication Date: 2013-04-19
    Description: Background Only patients with wild-type (WT) KRAS tumors benefit from anti-epidermal growth factor receptor (EGFR) monoclonal antibodies (Mabs) in metastatic colorectal cancer (mCRC). Pyrosequencing is now widely used for the determination of KRAS mutation burden and a conservative cut-off point of 10% has been defined. Up until now, the impact of low-frequency KRAS mutations (〈10%) on the response to anti-EGFR Mabs has yet to be evaluated. Patients and methods Tumors from patients receiving anti-EGFR Mabs based on a WT genotype for KRAS , as determined using direct sequencing, have been retrospectively analyzed by pyrosequencing. Patients were categorized as WT (no KRAS mutation) or low-frequency mutation when KRAS mutation was 〈10% ( KRAS low MT). Results A total of 168 patients treated by anti-EGFR Mabs for mCRC were analyzed. According to pyrosequencing, 138 tumors remained KRAS WT, while 30 tumors were KRAS low MT. In the KRAS low MT and KRAS WT groups, the response rates were 6.7% and 37.0%, respectively, while stabilization amounted to 23.3% versus 32.6% and progression to 70% versus 29% ( P 〈 0.01). Progression-free survival (PFS) was 2.7 ± 0.5 months for KRAS low MT and was 6.0 ± 0.3 months for KRAS WT ( P 〈 0.01). Conclusions These results appear to validate consideration of low-frequency KRAS mutation tumors as positive, and justify a large-scale prospective study.
    Print ISSN: 0923-7534
    Electronic ISSN: 1569-8041
    Topics: Medicine
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  • 9
    Publication Date: 2012-10-10
    Description: Although most deoxyribonucleic acid (DNA) lesions are accurately repaired before replication, replication across unrepaired lesions is the main source of point mutations. The lesion tolerance processes, which allow damaged DNA to be replicated, entail two branches, error-prone translesion synthesis (TLS) and error-free damage avoidance (DA). While TLS pathways are reasonably well established, DA pathways are poorly understood. The fate of a replication-blocking lesion is generally explored by means of plasmid-based assays. Although such assays represent efficient tools to analyse TLS, we show here that plasmid-borne lesions are inappropriate models to study DA pathways due to extensive replication fork uncoupling. This observation prompted us to develop a method to graft, site-specifically, a single lesion in the genome of a living cell. With this novel assay, we show that in Escherichia coli DA events massively outweigh TLS events and that in contrast to plasmid, chromosome-borne lesions partially require RecA for tolerance.
    Keywords: Repair, Replication
    Print ISSN: 0305-1048
    Electronic ISSN: 1362-4962
    Topics: Biology
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  • 10
    Publication Date: 2014-07-22
    Description: Background: The cognitive consequences of carbon monoxide (CO) poisoning are well described. However, most studies have been carried out without an ad-hoc group of control subjects. The main aim of this study was to evaluate cognitive and psychiatric outcome after CO exposure during the storm Klaus in the South West of France (January 2009) in a homogeneous group of patients compared to a group of 1:1 paired controls. Methods: Patients and controls were asked to fill out questionnaires about quality of life and cognitive complaints. They then underwent a cognitive assessment derived from the Carbon Monoxide Neuropsychological Screening Battery. Psychiatric assessment was performed using subtests of the Mini International Neuropsychiatric Interview. Results: 38 patients and 38 paired controls were included (mean age 38.8 years) and evaluated 51 days after the poisoning. No difference was found between groups on the cognitive complaint questionnaire but patients had a lower quality of life than controls. Patients showed significantly lower cognitive performance than controls on processing speed, mental flexibility, inhibition and working and verbal episodic memories. Patients were more depressed than controls, and suffered more from post-traumatic stress disorder. Conclusions: We report the first study investigating cognitive and psychiatric outcome in consecutive patients after CO poisoning during a natural disaster, using a group comparison method. CO poisoning during storms needs to be dealt with adequately and clinicians should be aware of its possible consequences.
    Electronic ISSN: 1471-2377
    Topics: Medicine
    Published by BioMed Central
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