True Strength of Ceramic Fiber Bundles: Experiments and Simulations

A study on the strength of ceramic fiber bundles based on experimental and computational procedures is presented. Tests were performed on single filaments and bundles composed of two fibers with different nominal fiber counts. A method based on fiber rupture signals was developed to estimate the amount of filament rupture during the test. Through this method, the fiber bundle true strength was determined and its variation with the initial fiber count observed. By using different load-sharing models and the single filament data as input parameter, simulations were also developed to verify this behavior. Through different approaches between experiments and simulations, it was noted that the fiber bundle true strength increased with the fiber count. Moreover, a variation of the fibers’ final proportion in the bundles relative to the initial amount was verified in both approaches. Finally, discussions on the influence of different load-sharing models on the results are presented.     

Short-term treatment of gastric ulcer

Gastric ulcer is relatively infrequent, and clinical trials are often based on small-sized samples. The aim of this study was to define the gold standard therapy of active gastric ulcer. We included all single- or double-blind clinical trials on the short-term treatment of gastric ulcer. All the articles published over the period 1977–1994 were reviewed. Meta-analysis was done with both fixed and random effect models; results were shown using Galbraith's radial plot. Forty-eight papers comprising 52 studies were evaluated. Cimetidine, ranitidine, and famotidine proved significantly better than placebo [odds ratio (OR) and 95% confidence interval (CI 95%) at four to six weeks were: 2.67 (2.03–3.52), 3.94 (2.28–6.80), 1.76 (1.08–2.88), respectively]. Cimetidine and ranitidine had results comparable with the newer H₂ blockers [OR (CI 95%) at four weeks: 1.16 (0.91–1.47), 1.11 (0.80–1.55), respectively]. H₂ blockers were proved comparable with either sucralfate [OR (CI 95%) at eight weeks: 0.81 (0.37–1.79)] or bismuth [OR (CI 95%) at four to six weeks: 0.67 (0.37–1.20)]. Omeprazole is more effective than H₂ blockers [OR (CI 95%) at four weeks: 2.00 (1.57–2.55)]. It is concluded that H₂ blockers are preferred to either a placebo or sucralfate for short-term gastric ulcer treatment; the newer H₂ blockers do not have significant advantages over the older types; omeprazole can be regarded as the gold standard for active gastric ulcer treatment.The statistical analysis and computing with plot program was performed by G. Leandro, MD, Biostatistician. This work was performed under the auspices of the Roberto Farini Foundation for Gastroenterological Research.     

Green synthesis of Au decorated CoFe2O4 nanoparticles for catalytic reduction of 4-nitrophenol and dimethylphenylsilane oxidation

Gold nanoparticles (Au NPs) have been widely employed in catalysis. Here, we report on the synthesis and catalytic evaluation of a hybrid material composed of Au NPs deposited at the surface of magnetic cobalt ferrite (CoFe₂O₄). Our reported approach enabled the synthesis of well-defined Au/CoFe₂O₄ NPs. The Au NPs were uniformly deposited at the surface of the support, displayed spherical shape, and were monodisperse in size. Their catalytic performance was investigated towards the reduction of 4-nitrophenol and the selective oxidation of dimethylphenylsilane to dimethylphenylsilanol. The material was active towards both transformations. In addition, the LSPR excitation in Au NPs could be employed to enhance the catalytic performance, which was demonstrated in the 4-nitrophenol reduction. Finally, the magnetic support allowed for the easy recovery and reuse of the Au/CoFe₂O₄ NPs. In this case, our data showed that no significant loss of performance took place even after 10 reaction cycles in the oxidation of dimethylphenylsilane to dimethylphenylsilanol. Overall, our results indicate that Au/CoFe₂O₄ are interesting systems for catalytic applications merging high performances, recovery and re-use, and enhancement of activities under solar light illumination.

We present a cleaner chemical synthesis process of a magnetic recoverable Au/CoFe₂O₄ hybrid nanocomposite catalyst that has remarkable activity in catalytic reduction and oxidation, improved by surface plasmon resonance.