Fabrication and performance evaluation of new nanocomposite membranes based on sulfonated poly(phthalazinone ether ketone) for PEM fuel cells

The purpose of this work is to enhance the proton conductivity and fuel cell performance of sulfonated poly(phthalazinone ether ketone) (SPPEK) as a proton exchange membrane through the application of SrTiO₃ perovskite nanoparticles. Nanocomposite membranes based on SPPEK and SrTiO₃ perovskite nanoparticles were prepared via a casting method. The highest proton conductivity of nanocomposite membranes obtained was 120 mS cm⁻¹ at 90 °C and 95% RH. These enhancements could be related to the hygroscopic structure of SrTiO₃ perovskite nanoparticles and the formation of hydrogen bonds between nanoparticles and water molecules. The satisfactory power density, 0.41 W cm⁻² at 0.5 V and 85 °C, of the nanocomposite membrane (5 wt% content of nanoparticles) confirms their potential for application in the PEM fuel cells.

The purpose of this work is to enhance the proton conductivity and fuel cell performance of sulfonated poly(phthalazinone ether ketone) (SPPEK) as a proton exchange membrane through the application of SrTiO₃ perovskite nanoparticles.     

Bone Demineralization With Citric Acid Enhances Adhesion and Spreading of Preosteoblasts

Background: Previous studies have demonstrated that bone demineralization can improve consolidation in bone grafts. The biologic mechanisms underlying this phenomenon remain unclear. Methods: Twelve adult male guinea pigs were used in this experiment. Forty‐five bone samples removed from the calvaria of nine animals were divided in groups (n = 9) according to the time of demineralization with citric acid (50%, pH 1): 15, 30, 90, and 180 seconds and non‐demineralized samples (control). Preosteoblasts (MC3T3‐E1) were cultured on the bone samples for 24, 48, and 72 hours (n = 3). Fifteen samples removed from the remaining three animals were analyzed by scanning electron microcopy/energy dispersive spectrometry (SEM/EDS) after demineralization (n = 3). Results: The number of preosteoblasts increased significantly with time in all groups. The bone surface area covered by these cells increased with time, except in the control group. Intragroup differences occurred between 24 and 72 hours (P <0.05). Samples demineralized for 30 seconds showed greater area covered by preosteoblast cells than for the other times of demineralization in all periods of cell culture (P <0.05) without a statistically significant difference compared with 15 seconds. SEM/EDS showed diminished content of calcium (Ca) after 15 seconds of demineralization, but the Ca content increased after 180 seconds of demineralization (P <0.05). The phosphorus (P) amount increased significantly only after 30 seconds of demineralization (P <0.5). The sulfur (S) content was increased in demineralized samples in relation to non‐demineralized ones, reaching the highest level after 90 seconds, when the difference became significant in relation to all the other times of demineralization (P <0.05). Magnesium (Mg) content did not differ significantly between demineralized and non‐demineralized samples. Conclusions: Bone surfaces demineralized for 30 seconds increased the spreading of preosteoblasts as well as the surface area covered by these cells. Bone demineralization deserves to be studied in periodontal and maxillofacial regenerative procedures.     

miRNA-binding site polymorphism in IL-15RA gene in rheumatoid arthritis and systemic lupus erythematosus: correlation with disease risk and clinical characteristics

Clinical Rheumatology - MiRSNPs may interfere with mRNA stability through effects on microRNAs (miRNAs)-mRNA interactions via direct changes in miRNA binding site or effect on the secondary...     

Paraneoplastic rheumatic syndromes: report of eight cases and review of literature

Malignant neoplasms are associated with a wide variety of paraneoplastic rheumatological syndromes. The paraneoplastic nature should be based on specific criteria. We report a series of eight cases of paraneoplastic rheumatic syndromes revealing an underlying neoplasia. Our series consists of six men and two women, with a mean age of 46.1 (20-69?years). The first case is a hypertrophic osteoarthropathy of Pierre Marie that occurred in a 20-year-old man 1?month after treatment for his nasopharyngeal carcinoma; the paraclinical examinations showed lung and bone metastasis. The second case is that of a bilateral shoulder-hand syndrome revealing an invasive squamous cell carcinoma of the cervix in a 63-year-old woman. The third case involved a 69-year-old patient who had surgery 2?years ago for prostate adenocarcinoma and presented with polymyalgia rheumatica revealing bone metastasis. We also report two cases of leukemia in adults revealed by polyarthritis. The sixth observation is that of a paraneoplastic scleroderma that occurred concomitantly with prostate cancer. The seventh case of an acute arthritis showed a B lymphoma. The eighth case is that of a 52-year-old patient who presented with inflammatory arthralgias, and digital clubbing revealing a squamous cell carcinoma of the skin. Paraneoplastic rheumatism remains a rare event, but knowledge of it is essential for early diagnosis of underlying cancer.