BACKGROUND: The prevalence of obesity is increasing rapidly and abdominal obesity especially is known to be a risk factor for metabolic syndrome and other non-communicable diseases. Waist circumference percentile curves are useful tools which can help to identify abdominal obesity among the childhood and adolescent populations.
OBJECTIVE: To develop age- and sex-specific waist circumference (WC) percentile curves for multi-ethnic Malaysian children and adolescents aged 6.0-16.9 years. Subjects and methods. A total of 16,203 participants comprising 8,093 boys and 8,110 girls recruited from all regions of Malaysia were involved in this study. Height, weight, WC were measured and BMI calculated. Smoothed WC percentile curves and values for the 3rd, 5th, 10th, 25th, 50th, 75th, 90th, 95th and 97th percentiles were constructed using the LMS Method.
RESULTS: WC was found to increase with age in both sexes, but boys had higher WC values at every age and percentile. Z-scores generated using the UK reference data shows that Chinese children had the highest WC compared to Malays, Indians and other ethnicities. Comparisons with other studies indicate that at the 50th percentile, Malaysian curves did not differ from the UK, Hong Kong and Turkish curves, but at the 90th percentile, Malaysian curves were higher compared with other countries, starting at 10 years of age. The 90th percentile was adopted as the cut-off point to indicate abdominal obesity in Malaysian children and adolescents.
CONCLUSION: These curves represent the first WC percentiles reported for Malaysian children, and they can serve as a reference for future studies.
In this work we have tried to prepare Ni and Ag doped ZnO nanopowders using the sol gel technique. The influence of Ni and Ag (1, 3 and 5 mol.%) on the crystalline structure and optical properties of ZnO was investigated. The samples were characterized by XRD, FTIR and UV-visible spectrophotometer. XRD patterns confirmed the wurtzite formation of doped and undoped ZnO nanopowders. The average crystallite sizes of the prepared samples found from XRD were 19 nm for undoped ZnO, from 17 to 22 nm for Ni-ZnO and from 19 to 26 nm for Ag-ZnO. The average crystallite size of Ag-ZnO increased with increasing Ag contents. Different optical properties of Ni-ZnO and Ag-ZnO nanopowders were observed for different Ni and Ag content. The band gaps of Ni-ZnO and Ag-ZnO nanopowders were lower than that of the undoped ZnO (3.1 eV). The band gaps of Ag-ZnO were lower than that of Ni-ZnO. The optical properties of ZnO were enhanced by Ni (mol.%) in the UV region and by Ag (3 and 5 mol.%) in the visible region.