Cellulose nanocrystals-reinforced waterborne epoxy coatings with enhanced corrosion resistance for steel.

The practical applications of waterborne epoxy coatings are limited due to their poor barrier properties caused by the formation of numerous micropores and defects during the curing process. Herein, cellulose nanocrystals (CNCs)-reinforced waterborne epoxy coatings were fabricated by the direct addition of 0.2-1.0 wt% CNCs to waterborne epoxy emulsion followed by amine curing agent addition and spray coating. The incorporation of 0.2-0.5 wt% CNCs had no discernible impact on the stability of the waterborne epoxy emulsion. This led to the uniform dispersion of CNCs in the cured coating matrix, as evidenced by differential scanning calorimetry analysis. Because of the good compatibility, 0.2-0.5 wt% CNCs-reinforced epoxy coatings exhibited superior corrosion protection performance for steels. The impedance modulus of these coatings remained at 108 Ω cm2 after being immersed in a 3.5 wt% NaCl solution for 21 d. The hydroxyl groups present on the CNC surface undergo a reaction with the epoxy group, enhancing intermolecular interaction and leading to the formation of a defect-free dense structure that improves coating barrier properties. However, the incorporation of an excessive amount of CNCs (i.e., 0.8 and 1.0 wt%) significantly compromised the corrosion resistance of epoxy coatings due to aggregation-induced coating defects. Overall, this study provides a facile and green strategy for corrosion resistance improvement of waterborne epoxy coatings.

Homograft replacement of the mitral valve: eight-year results.

OBJECTIVE: The objective of this study was to assess whether the mitral homograft represents a valuable alternative for complete or partial mitral valve replacement. METHODS: Since 1993, 104 patients underwent mitral homograft replacement surgery. The mean age was 38 +/- 15 years. The causes of mitral valve disease were rheumatic disease (n = 76), infective endocarditis (n = 24), and others (n = 4). Sixty-five of these procedures were total homografts, and 39 were partial homografts. RESULTS: The mean follow-up was 52 +/- 35 months (maximum, 117 months). Overall hospital mortality was 4 (3.8%) of 104 patients and 2.5% versus 8.7% for patients without endocarditis and with endocarditis, respectively (P <.19). There were 9 late deaths (cardiac, 4; noncardiac, 5). There have been 5 early (<3 months) and 10 late reoperations. Of the remaining 77 patients, New York Heart Association class was I in 61, II in 14, and III in 2. Four patients had endocarditis, and 5 had an ischemic or hemorrhagic event. Freedom from major cardiac events was 71% +/- 6% at 8 years (partial at 81% vs total at 63%, P <.19). Among patients with a total homograft, freedom from major cardiac events was 61% +/- 9% and 85% +/- 8% at 6 years in patients younger than and older than 40 years, respectively (P =.09). CONCLUSION: The risk of early dysfunction related to a mismatch between the mitral homograft and the patient's valve is the main pitfall of the technique. Beyond that stage, the results were comparable with those of bioprostheses in a cohort of young patients.

Castleman's disease associated with myasthenia gravis.

Castleman's disease presents as a peculiar type of lymph node hyperplasia. Traditionally, the disease has been classified on clinical grounds (solitary or multicentric) and by histologic appearance (hyaline vascular pattern, plasma cell predominance, or mixed lesions). It is now increasingly clear that there are different etiologies for each of these different subtypes. Reported associations include POEMS syndrome (polyneuropathy, organomegally, endocrinopathy, monoclonal gammopathy, and skin changes), paraneoplastic pemphigus, Hodgkin's disease, and follicular dendritic cell sarcoma. We present a case of Castleman's disease associated with myasthenia gravis, the third reported case in the literature. We discuss Castleman's disease and review the literature.