Background/Aims: Neighborhood socioeconomic status (SES) can affect cognitive function. We assessed cognitive function and cognitive impairment among community-dwelling elderly in a multi-ethnic urban low-SES Asian neighborhood and compared them with a higher-SES neighborhood. Methods: The study population involved all residents aged ≥60 years in two housing estates comprising owner-occupied housing (higher SES) and rental flats (low SES) in Singapore in 2012. Cognitive impairment was defined as <24 on the Mini Mental State Examination. Demographic/clinical details were collected via questionnaire. Multilevel linear regression was used to evaluate factors associated with cognitive function, while multilevel logistic regression determined predictors of cognitive impairment. Results: Participation was 61.4% (558/909). Cognitive impairment was found in 26.2% (104/397) of residents in the low-SES community and in 16.1% (26/161) of residents in the higher-SES community. After adjusting for other sociodemographic variables, living in a low-SES community was independently associated with poorer cognitive function (β = –1.41, SD = 0.58, p < 0.01) and cognitive impairment (adjusted odds ratio 5.13, 95% CI 1.98–13.34). Among cognitively impaired elderly in the low-SES community, 96.2% (100/104) were newly detected. Conclusion: Living in a low-SES community is independently associated with cognitive impairment in an urban Asian society.

The Ni-P/SiC composite coating was prepared by chemical deposition technique. The corrosion behavior of electroless Ni-P/SiC composite coating was investigated. The results show that the corrosion resistance of electroless composite coating decreased with the increasing SiC concentration in bath solution. There were some little pores among the composite coating and the pores would increased with the increasing SiC content among the coating, which made the corrosion resistance decreased. The corrosion rate increased with the increasing temperature of corrosion liquid. The corrosion resistance was improved for T gradient electroless Ni-P/SiC composite coating comparing with the single electroless composite coating whether the corrosion solution was acid solution or alkaline solution. The corrosion rate were less than 5 mg/cm2for all specimens in alkaline solution, which indicated that the corrosion resistance of electroless composite coating was better than that in acid solution.

The Ni-P/SiC composite coating was prepared by chemical deposition technique. The micro-structure and wear behavior of electroless Ni-P/SiC composite coating was investigated. The results show that the composite coating was dense and no any defects at the interface between substrate and electroless composite coating. Its thickness could reach 40 μm. Wear resistance was increased with the increasing content of SiC particles for single composite coating when the SiC concentration was less than 6g/L, then decreased with the increased SiC concentration. The wear resistance of gradient composite coating was improved above 16% comparing with the single composite coating. The wear resistance of T1gradient coating was best for all electroless Ni-P/SiC composite coatings because the bonding strength was improved owing to the gradient change of SiC content.

The surface composite layer Ni/WC on the cast iron substrate was fabricated through vacuum infiltration casting technique using Ni-based powder and WC particles with different content as raw materials. The micro-structure of infiltrated layer was compact for all infiltrated layer with different WC content, and WC particles distributed uniformly. The surface infiltrated layer was mainly composed of WC particle, intermetallic compound and solid solution. The thermal cycles were beyond 108 times when the infiltrated layer peeled off, which indicated that the specimen with infiltrated layer offered excellent thermal fatigue property. The oxidation rate of substrate was nearly three times as large as that of the infiltrated layer with 20% WC content. The oxidation resistance of the infiltrated layer improved obviously comparing with the substrate because the oxide layer for infiltrated layer was compact.

The plate of the heat exchanger leaked owing to its corrosion during the running of the whole equipment. The composition of the failure plate, microstructure, corrosion appearance and the chemical composition of the corrosion products were analyzed through Optical microscope, scanning electron microscope and chemical analysis method to find out the reason of the failure. The results show that the chemical composition of the plate meet the requirement of S31254 (254SMO) according to standard A240 /A240M-2005. The main phase was austenite among which the ferrite distributed in stripe. The corrosion happened firstly at the ferrite area under the condition of running medium with chlorine ion and sulfur ion. Incomplete solution of ferrite during the solid solution treatment was the main cause of spot corrosion, which ultimately resulted in the leaking failure owing to the corrosion.