Interface characteristics and wear resistance of Ni-B_(4)C plated ZTA reinforced high chromium cast iron composite

A chemical composite plating of Ni-B_(4)C was used to prepare the surface-modified zirconia toughened alumina(ZTA)ceramic particles.The ceramic preforms were prepared by the plated ZTA and sodium silicate solution binder,followed by casting infiltration to prepare the ZTA particles reinforced high chromium cast iron(HCCI)composites.The result reveals that a distinct interface layer forms at the ZTA/HCCI interface,which consists of phases of ZrB_(2),FeB,Fe_(2)B,and NaSiO_(4).The interfacial wettability between ZTA and HCCI is improved by the diffusion and reaction of Ni and B_(4)C.The wear test reveals that the Ni-B_(4)C plated ZTA particles can effectively improve the wear resistance of the ZTA/HCCI composite,and the wear rate of the composite is decreased to 11.6%of HCCI.

Alterations of intestinal flora and the effects of probiotics in children with recurrent respiratory tract infection

Background Recurrent respiratory tract infection (RRTI) is a disease occurred frequently in preschool children.Methods A total of 120 RRTI children were randomly divided into active group,remission group,intervention group and control group,meanwhile 30 healthy children were selected as the healthy group.Children in the intervention group were given oral Bifidobaeterium tetravaccine tablets (Live) for 2 months,while the control group received routine treatment.Stool sample were detected to analyze the bacterial strains.The occurrence of respiratory tract infection (RTI) was compared between different groups during 1 year follow-up.Results Compared with the healthy group,the number of Bifidobacteria and Lactobacilli in the active group,remission group,intervention group and control group was significantly decreased (P < 0.05).The number of Bifidobacteria and Lactobacilli in the intervention group was significantly higher compared to other RRTI groups (P < 0.05).During the follow-up period,the average annual frequency of different acute RTI and use of antibiotics were significantly reduced (P < 0.05),the average duration of cough,fever and use of antibiotics at each episode were also significantly shortened (P < 0.05) in the intervention group compared to the control group.Conclusions Children with RRTI are susceptible to intestinal flora imbalance.Oral probiotics can effectively improve the RRTI intestinal microecological balance in children and reduce the frequency of RTI.