Mechanical Properties of Natural Fiber Reinforced Foamed Concrete.

The mechanical characterization of plain foamed concrete (PFC) and fiber-reinforced foamed concrete (FRFC) with a density of 700 kg/m3 was performed with compression and tension tests. FRFC was reinforced with the natural fiber henequen (untreated or alkaline-treated) at volume fractions of 0.5%, 1% and 1.5%. Polypropylene fiber reinforcement was also used as a reference. For all FRFCs, the inclusion of the fibers enhanced the compressive and tensile strengths and plastic behavior, which was attributed to the increase of specimen integrity. Under compressive loading, after the peak strength, there was no considerable loss in strength and a plateau-like regime was observed. Under tensile loading, the fibers significantly increased the tensile strength of the FRFCs and prevented a sudden failure of the specimens, which was in contrast to the brittle behavior of the PFC. The tensile behavior enhancement was higher when treated henequen fibers were used, which was attributed to the increase in the fiber-matrix bond produced by the alkaline treatment. The microscopic characterization showed that the inclusion of fibers did not modify the air-void size and its distribution. Higher energy absorption was observed for FRFCs when compared to the PFC, which was attributed to the enhanced toughness and ductility by the fibers. The results presented herein warrant further research of FRFC with natural henequen fibers for engineering applications.

Clinical study of the correlation between complement factor H polymorphism and age-related macular degeneration.

This study aimed to investigate the correlation between age-related macular degeneration (AMD) of the liver-kidney yin-deficiency type and complement factor H (CFH) polymorphism, and to determine whether the C allele of the T1277C (Y402H) variant is a risk factor for this condition. We performed a case-control investigation of 60 patients with liver-kidney yin-deficiency AMD and 60 normal control subjects. Peripheral blood was collected from each participant for DNA extraction. Following amplification by polymerase chain reaction, the DNA samples were sequenced, and polymorphism of the CFH gene was examined. Data were analyzed with the chi-square test, with P < 0.05 signifying statistical significance. The frequency of the C allele was significantly higher in the wet than in the dry AMD group (P = 0.044). In addition, the TC and CC genotypes were markedly more common in the former than in the control group (P = 0.013), and there was a significant difference in the distribution of the T and C alleles between wet AMD patients and control subjects (P < 0.05). Based on this, we conclude that liver-kidney yin-deficiency AMD is associated with the C allele and TC and CC genotypes of the CFH Y402H polymorphism. Among patients with this condition, CFH genotypes were normally distributed. The principal CFH genotypes that induce liver-kidney yin-deficiency AMD are the mutant homozygote CC and heterozygote TC forms. Moreover, C allele carriers are at higher risk of developing this disease.