Analysis of n-Si(111) during photocurrent oscillations in Fluoridic solutions

The surface condition of n-Si(111) exposed to an acidic fluoride solution under white light illumination is strongly influenced by the applied electrode potential. Photocurrent oscillations at n-Si(111) are investigated in-situ by ellipsometry and Fourier-transform infrared spectroscopy (FTIR). In-situ ellipsometric data show that the current oscillation is concomitant with the fluctuation of the optical parameters D and Y. The FTIR investigations revelate that the Si-O signal has a self-oscillating mode and varies by more than ± 20% what explains the fluctuation in D and Y.The surface condition of n-Si(111) exposed to an acidic fluoride solution under white light illumination is strongly influenced by the applied electrode potential. Photocurrent oscillations at n-Si(111) are investigated in-situ by ellipsometry and Fourier-transform infrared spectroscopy (FTIR). In-situ ellipsometric data show that the current oscillation is concomitant with the fluctuation of the optical parameters D and Y. The FTIR investigations revelate that the Si-O signal has a self-oscillating mode and varies by more than ± 20% what explains the fluctuation in D and Y

Membrane Destabilization Induced By Beta-Amyloid Peptide 29-42: Importance Of The Amino-Terminus

Increasing evidence implicates interactions between Abeta-peptides and membrane lipids in Alzheimer's disease. To gain insight into the potential role of the free amino group of the N-terminus of Abeta29-42 fragment in these processes, we have investigated the ability of Abeta29-42 unprotected and Abeta29-42 N-protected to interact with negatively-charged liposomes and have calculated the interaction with membrane lipids by conformational analysis. Using vesicles mimicking the composition of neuronal membranes, we show that both peptides have a similar capacity to induce membrane fusion and permeabilization. The fusogenic effect is related to the appearance of non-bilayer structures where isotropic motions occur as shown by 31P and 2H NMR studies. The molecular modeling calculations confirm the experimental observations and suggest that lipid destabilization could be due to the ability of both peptides to adopt metastable positions in the presence of lipids. In conclusion, the presence of a free or protected (acetylated) amino group in the N-terminus of Abeta29-42 is therefore probably not crucial for destabilizing properties of the C-terminal fragment of Abeta peptides

A Phase III randomized study comparing a chemotherapy with cisplatin and etoposide to a etoposide regimen without cisplatin for patients with extensive small-cell lung cancer

Introduction: In a literature meta-analysis, we showed survival benefits for regimens including cisplatin [hazard ratio (HR) 0.61; 95% confidence interval (CI), 0.57-0.66] and for those including etoposide (HR 0.65; 0.61-0.69). That benefit was mainly observed when etoposide alone or in combination with cisplatin was included in the chemotherapy regimens. Our objective was to determine if chemotherapy with both drugs improves survival in comparison to a non-platinum regimen with etoposide. Methods: Extensive small-cell lung cancer patients were randomized between cisplatin-etoposide (CE) and ifosfamide + etoposide + epirubicin regimen (IVE) between 2000 and 2013. Results: 176 and 170 eligible patients were allocated to CE and IVE (315 deaths were required before analysis), respectively. Objective response rates were not significantly different: 60% with CE and 59% with IVE. No statistically significant difference in median survival and 1-year and 2-year was observed with rates of 9.6 months, 31 and 5% for CE and 10 months, 39 and 9% for IVE, respectively. HR was 0.84 (95% CI 0.68-1.05, p = 0.16). Only two prognostic factors for survival were retained in multivariate analysis: sex with HR = 0.69 (95% CI 0.49-0.97, p = 0.03) and performance status with HR = 0.53 (95% CI 0.49-0.97, p < 0.0001). After adjustment for these prognostic factors, HR for survival was 0.83 (95% CI 0.65-1.08, p = 0.17). There was more thrombopenia in the CE regimen and more leukopenia with IVE. Conclusion: Combination of CE failed to improve survival in comparison to an etoposide-containing regimen without cisplatin. Clinical Trial Registration: https://clinicaltrials.gov/ct2/show/NCT00658580?term=ELCWP+01994&rank=1, identifier NCT00658580. © 2017 Berghmans, Scherpereel, Meert, Giner, Lecomte, Lafitte, Leclercq, Paesmans and Sculier

Chemical and electrochemical oxidation of silicon surfaces functionalized with APTES: the role of surface roughness in the AuNPs anchoring kinetics

Oxidation of Si(111) surfaces is a procedure widely used for their further functionalization with 3-aminopropyltriethoxysilane (APTES). In the present work, the formation of silicon oxide is carried out by chemical and electrochemical oxidation of the hydrogenated-silicon surfaces, giving rise to Si-OxChem and Si-OxEchem surfaces, respectively. Both surfaces are then functionalized with APTES solution to form an aminopropylsilane (APS) film, using two quite different concentrations of APTES (0.001 and 0.1% v/v), to compare two limiting situations. At the lowest APTES concentration, the comparison of the kinetics of gold nanoparticles (AuNPs) anchoring process on both surfaces is found to be quite different, not only in the initial rate of NPs anchoring but also in the maximum percentage of coverage. In contrast, the kinetics behavior is almost the same when the surfaces are modified with the highest APTES concentration, reaching the same value of surface coverage. The different or similar behavior of both surfaces is analyzed by a careful characterization of Si-OxChem and Si-OxEchem surfaces using XP spectroscopy and AFM measurements, before and after APS functionalization. The significant differences in the surface roughness of the Si-Ox samples, together with the determination of the number of −NH3 + moieties after silanization at both APTES concentrations, leads to the conclusion that the availability of −NH3 + moieties is dependent on two factors: the roughness of the Si-OxChem and Si-OxEchem surfaces as well as the concentration of the APTES solutions. When the APS layer is formed at the lowest APTES concentration, surface roughness controls the number of different types of nitrogen functional groups. In contrast, at the highest APTES concentration, the surface roughness does not have any significant role in the number of −NH3 + moieties present on both surfaces. Because the kinetics of AuNPs anchoring depends mainly on the probability of interacting with the −NH3 + groups, the above characterization allows us to explain in a consistent way the kinetics behavior observed for each particular condition of surface preparation.Fil: Klug, Joaquín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Pérez, Luis Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Coronado, Eduardo A.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Lacconi, Gabriela Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentin