1,748 research outputs found
Chitosan and its char as fillers in cement-base composites: A case study
No full textThe continuous research of new functional materials combining both advanced properties and increased sustainability has dramatically risen up in the last decades. Instead of searching for new solutions, composites (formed by a combination of already present materials) are subject of different studies due to their capability of merging the advantages of components. Hence, chitosan, a biowaste-derived biopolymer, has been thermally-converted into chars by pyrolysis treatment. Subsequently, both chitosan and its char are introduced into cementitious matrix forming cement-based composites. The analysis of the mechanical properties of these materials evidenced that char-containing composites show an incipient fracture toughness capability, very appealing for possible structural applications
Analysis of human mitochondrial genome co-occurrence networks of Asian population at varying altitudes
No full textNetworks have been established as an extremely powerful framework to understand and predict the behavior of many large-scale complex systems. We studied network motifs, the basic structural elements of networks, to describe the possible role of co-occurrence of genomic variations behind high altitude adaptation in the Asian human population. Mitochondrial DNA (mtDNA) variations have been acclaimed as one of the key players in understanding the biological mechanisms behind adaptation to extreme conditions. To explore the cumulative effects of variations in the mitochondrial genome with the variation in the altitude, we investigated human mt-DNA sequences from the NCBI database at different altitudes under the co-occurrence motifs framework. Analysis of the co-occurrence motifs using similarity clustering revealed a clear distinction between lower and higher altitude regions. In addition, the previously known high altitude markers 3394 and 7697 (which are definitive sites of haplogroup M9a1a1c1b) were found to co-occur within their own gene complexes indicating the impact of intra-genic constraint on co-evolution of nucleotides. Furthermore, an ancestral ‘RSRS50’ variant 10,398 was found to co-occur only at higher altitudes supporting the fact that a separate route of colonization at these altitudes might have taken place. Overall, our analysis revealed the presence of co-occurrence interactions specific to high altitude at a whole mitochondrial genome level. This study, combined with the classical haplogroups analysis is useful in understanding the role of co-occurrence of mitochondrial variations in high altitude adaptation
Measurement of B0 --> Ds(*)+D*- branching fractions and B0 --> Ds*+D*- polarization with a partial reconstruction technique
No full textWe present a study of the decays B0→Ds (*)+D*-, using 20.8 fb-1 of e +e- annihilation data recorded with the BABAR detector. The analysis is conducted with a partial reconstniction technique, in which only the Ds(*)+ and the soft pion from the D*- decay are reconstructed. We measure the branching fractions B(B0→Ds+D*-) = (1.03±0.14±0.13±0.26)% and B(B0→D* s+D*-) = (1.97±0.15±0. 30±0.49)%, where the first error is statistical, the second is systematic, and the third is the error due to the Ds+ → φπ+ branching fraction uncertainty. From the B 0→D*s+D*- angular distributions, we measure the fraction of longitudinal polarization ΓL/Γ = (51.9±5.0±2.8)%, which is consistent with theoretical predictions based on factorization
Measurement of branching fractions of color-suppressed decays of the (B)over-bar(0) meson to D-(*)0 pi(0), D-(*)0 eta, D-(*)0 omega, and D-0 eta `
No full textUsing a sample of 88.8×10^6 BB̅ events collected with the BABAR detector at the PEP-II storage rings at the Stanford Linear Accelerator Center, we measure the branching fractions of seven color-suppressed B-meson decays: B(B0→D0π0)=[2.9±0.2(stat)±0.3(syst)]×10-4, B(B0→D*0π0)=[2.9±0.4(stat)±0.5(syst)]×10-4, B(B0→D0η)=[2.5±0.2(stat)±0.3(syst)]×10-4, B(B0→D*0η)=[2.6±0.4(stat)±0.4(syst)]×10-4, B(B0→D0ω)=[3.0±0.3(stat)±0.4(syst)]×10-4, B(B0→D*0ω)=[4.2±0.7(stat)±0.9(syst)]×10-4, and B(B0→D0η′)=[1.7±0.4(stat)±0.2(syst)]×10-4. We set the 90% confidence-level upper limit: B(B0→D*0η′)<2.6×10-4. The channels B0→D*0η, D*0ω, and D0η′ are seen with more than five-sigma statistical significance. All of these branching fractions are significantly larger than theoretical expectations based on the “naive” factorization model
Improving rubber concrete strength and toughness by plasma-induced end-of-life tire rubber surface modification
No full textThis study evaluates the effectiveness of using different plasma treatments to favor the compatibility between rubber and a cement matrix in composites,
thus leading to a different surface reactivity of the rubber component. Plasmatreated rubbers were introduced into two d ifferent types of concr ete.
Mechanical tests highlighted that Portland concrete composites filled with N2/H2 plasmatreated rubber had increased flexural strength, toughness, and
compression strength compared to composites containing untreated rubber. A scaling law is also proposed to qualitatively discriminate between
related effects due to topological/roughness or intrinsic/chemical adhesion modifications. Plasma treatment can improve both intrinsic adhesion
and roughness of the rubber–cement interface and thus the overall concrete strength and toughness
Selenium-doped hydroxyapatite nanoparticles for potential application in bone tumor therapy
No full textIn the present study we have studied the incorporation and release of selenite ions (SeO32−) in hydroxyapatite nanoparticles for the treatment of bone tumors. Two types of selenium-doped hydroxyapatite (HASe) nanoparticles (NPs) with a nominal Se/(P + Se) molar ratio ranging from 0.01 up to 0.40 have been synthesized by a new and mild wet method. The two series of samples were thoroughly characterized and resulted to be slightly different in chemical composition, but they had similar properties in terms of morphology and degree of crystallinity. Selenium release from HASe was investigated under neutral and acidic conditions to simulate both healthy tissues and the low-pH environment surrounding a tumor mass, respectively. The comparison of the release profiles at two pH values clearly showed the possibility of modulating the Se release by simply changing the amount of Se in the HASe particles. The correlation between the physicochemical properties of HASe and their dissolution as a function of pH has been also investigated to facilitate future application of the NPs as chemotherapeutic adjuvant agents. Finally, the cytotoxic activity of HASe was evaluated using prostate (PC3) and breast (MDA-MB-231) cancer cells as well as healthy human bone marrow stem cells (hBMSc). HASe NPs exerted a good cytocompatibility at low concentration of Se but, with high Se doping concentration, they displayed strong cytotoxicity
Measurement of B0 ---> D(*)+ D*- branching fractions and B0 ---> D*+(s) D*- polarization with a partial reconstruction technique
No full textWe present a study of the decays B0→Ds(*)+D*-, using 20.8 fb-1 of e+e- annihilation data recorded with the BABAR detector. The analysis is conducted with a partial reconstruction technique, in which only the Ds(*)+ and the soft pion from the D*- decay are reconstructed. We measure the branching fractions B(B0→Ds+D*-)=(1.03±0.14±0.13±0.26)% and B(B0→Ds*+D*-)=(1.97±0.15±0.30±0.49)%, where the first error is statistical, the second is systematic, and the third is the error due to the Ds+→φπ+ branching fraction uncertainty. From the B0→Ds*+D*- angular distributions, we measure the fraction of longitudinal polarization ΓL/Γ=(51.9±5.0±2.8)%, which is consistent with theoretical predictions based on factorization
Combined Effect of Citrate and Fluoride Ions on Hydroxyapatite Nanoparticles
No full textCitrate and fluoride ions are two constituents of dental enamel hydroxyapatite (HA) nanocrystals. Their individual effect on HA crystallization has already been studied, and it was proven that both citrate and fluoride ions regulate HA crystal growth. However, the combined effect of citrate and fluoride ions on HA nanocrystals has never been reported so far. In this work, we have prepared citrate-fluoride-HA (citrate-FHA) nanoparticles in mild conditions, and we have studied the evolution of morphology and composition upon maturation. We have proven that even in the presence of citrate, fluoride ions are incorporated in the apatitic structure (replacing hydroxyl ions) and accelerate the crystallization process. Interestingly, citrate-FHA nanoparticles exhibit a flattened hexagonal rod-like morphology in contrast to the needle-like platelet morphology of citrate-HA. The density of citrate ions bound on the citrate-FHA surface is higher than that on citrate-HA. Moreover, the relative amount of unidentate citrate-Ca2+ adducts versus the ionic-like ones is higher for citrate-FHA than for citrate-HA. Our results provide a deeper understanding of the combined effect of citrate and fluoride ions on HA nanocrystals that can be used for the design of advanced biomaterials with tailored features, for a better comprehension of the enamel biomineralization process, and for the synthesis of enamel-like nanocrystals
Measurement of D-s(+) and D-s(*+) production in B meson decays and from continuum e(+)e(-) annihilation at root s=10.6 GeV
No full textNew measurements of D-s(+) and D-s(*+) meson production rates from B decays and from q(q) over bar continuum events near the Y(4S) resonance are presented. Using 20.8 fb(-1) of data on the Y(4S) resonance and 2.6 fb(-1) off-resonance, we find the inclusive branching fractions B(B-->Ds+X) = (10.93+/-0.19+/-0.58+/-2.73)% and B(B-->Ds*+X) = (7.9+/-0.8+/-0.7+/-2.0)%, where the first error is statistical, the second is systematic, and the third is due to the D-s(+)-->phipi(+) branching fraction uncertainty. The production cross sections sigma(e(+)e(-)-->Ds+X)xB(D-s(+)-->phipi(+)) = 7.55+/-0.20+/-0.34 pb and sigma(e(+)e(-)-->Ds*+/-X)xB(D-s(+)-->phipi(+)) = 5.8+/-0.7+/-0.5 pb are measured at center-of-mass energies about 40 MeV below the Y(4S) mass. The branching fractions SigmaB(B-->D-s((*)+)(D) over bar ((*))) = (5.07+/-0.14+/-0.30+/-1.27)% and SigmaB(B-->D-s(*+)(D) over bar ((*))) = (4.1+/-0.2+/-0.4+/-1.0)% are determined from the D-s((*)+) momentum spectra. The mass difference m(D-s(+)) -m(D+) = 98.4+/-0.1+/-0.3 MeV/c(2) is also measured
Measurement of B-0 -> D-s(*)D+*(-) branching fractions and B-0 -> D-s*D+*(-) polarization with a partial reconstruction technique
No full textWe present a study of the decays B-0 --> D-s((*)) D*-, using 20.8 fb(-1) of e(+)e(-) annihilation data recorded with the BABAR detector. The analysis is conducted with a partial reconstruction technique, in which only the D-s((*)+) and the soft pion from the D*- decay are reconstructed. We measure the branching fractions B(B-0 --> Ds+D*-) = (1.03 +/- 0.14 +/- 0.13 +/- 0.26)% and B(B-0 --> D-s(*+) D*-) = (1.97 +/- 0.15 +/- 0.30+/- 0.49)%, where the first error is statistical, the second is systematic, and the third is the error due to the D-s(+) --> phipi(+) branching fraction uncertainty. From the B-0 --> D-s(*+) D*- angular distributions, we measure the fraction of longitudinal polarization Gamma(L)/Gamma = (51.9 +/- 5.0 +/- 2.8)%, which is consistent with theoretical predictions based on factorization
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