Mass transfer characteristics, rheological behavior and fractal dimension of anammox granules: The roles of upflow velocity and temperature.

In this study, the mass transfer, rheological behavior and fractal dimension of anaerobic ammonium oxidation (anammox) granules in upflow anaerobic sludge blanket reactors at various temperatures (8.5-34.5°C) and upflow velocities (0.06, 0.18mh-1) were investigated. The results demonstrated that a lower temperature increased the external mass transfer coefficient and apparent viscosity and impaired the performance of anammox granules. The external mass transfer coefficient was decreased, but efficient nitrogen removal of up to 96% was achieved under high upflow velocity, which also decreased the apparent viscosity. Furthermore, a fractal dimension of up to 2.93 achieved at low temperature was higher than the previously reported values for mesophilic anammox granules. A higher upflow velocity was associated with the lower fractal dimension. Because of the disturbance in granule flaking, the effectiveness factor was less suitable than the external mass transfer coefficient for characterization of mass transfer resistance.

Individual and combined inhibition of phenol and thiocyanate on microbial activity of partial nitritation.

This study evaluated the individual and interactive effect of phenol and thiocyanate (SCN-) on partial nitritation (PN) activity using batch test and response surface methodology. The IC50 of phenol and SCN- on PN sludge were 5.6 and 351 mg L-1, respectively. The PN sludge was insensitive to phenol and SCN- at levels lower than 1.77 and 43.3 mg L-1, respectively. A regression model equation was developed and validated to predict the relative specific respiration rate (RSRR) of PN sludge exposed to different phenol and SCN- concentrations. In the range of independent variables, the most severe inhibition was observed with a valley value (17%) for RSRR, when the phenol and SCN- concentrations were 4.08 and 198 mg L-1, respectively. An isobole plot was used to judge the combined toxicity of phenol and SCN-, and the joint inhibitory effect was variable depending on the composition and concentration of the toxic components. Furthermore, the toxic compounds showed independent effects, which is the most common type of combined toxicity.

[Characterization and spectral analysis of the stable mineral phases alpha, beta-FeOOH included in iron oxyhydroxides].

In the present work, based on the stable phase of alpha-FeOOH and beta-FeOOH easily formed in ferric solutions of Fe (NO3)3 and FeCl3 at the appropriate pH values, respectively, the phase and crystallizability, morphologies and sizes for the particles of FeOOH minerals prepared under the conditions of heating at 40 and 70 degreeC, and magnetic stirring at 25 degreeC were identified and examined by X-ray diffraction (XRD), transmission/scanning electron microscopy (TEM/SEM) and laser scattering particle analyzer. Meanwhile the surface chemistry properties were also detected and analyzed by Fourier transform infrared spectrometer (FTIR). Investigation results showed that the prepared minerals Gth-T70 (alpha-FeOOH), Aka-T40 and Aka-T70 (beta-FeOOH) have good properties of nanocrystallity, homogeneous particles and higher specific surface areas, which induced that the above alpha, beta-FeOOH are potentially excellent adsorbent materials for removal of some contaminants in circumstances.

[Spectral analysis of FeOOH prepared through hydrolysis and neutralization of ferric solutions under different conditions].

In the present work, the iron oxyhydroxides were prepared by hydrolysis and neutralization of ferric ion from FeCl3, Fe(NO3)3 and Fe2 (SO4)3 salts, under the conditions of various pH values and aging for about 6 days at 60 degrees C. These iron minerals were identified and characterized using X-ray diffraction (XRD), infrared spectroscopy (IR) and scanning electron microscopy (SEM). In addition, particle size distributions of FeOOH suspension were also determined by LS-230 model laser grainsize analyzer. Results showed that ferrihydrite formed in the ferric solutions containing Cl-, NO3- and SO4(2-) at pH values of 8 and 10. It was testified that the presence of Cl- was favorable for the formation of akaganéite. Meanwhile, the poor crystalline goethite phase was observed to be formed in FeCl3 or Fe(NO3)3 solution, but not be formed in Fe2 (SO4)3 solution at pH 12. It indicated that the presence of SO4(2-) obviously inhibited the formation of goethite. However, the goethite phase formed in Fe2 (SO4)3 solution with addition of ferrous ion, indicating that ferrous ion could promote the formation of goethite in SO4(2-) -rich solution. In addition, it was usually easy for the crystalline goethite to be transformed from the above generated ferrihydrite precipitates by aging at 60 degrees C. Furthermore, the phase of akaganéite also was obtained in the Cl(-) -rich acid (pH < or = 5) solution by aging at 60 degrees C. In conclusion, the prepared FeOOH samples show some differences in their properties such as the phase, surface properties, morphology structures and particle size.

Report on childhood obesity in China (7). Comparison of NCHS and WGOC.

OBJECTIVE: To test the validity of Working Group on Obesity in China (WGOC) reference in screening childhood obesity using obesity-related metabolic syndrome (MS) and its components as disease risk evidence. METHODS: A total of 2020 adolescents (1007 boys and 1013 girls) aged 14-16 years were sampled in Beijing, China. Anthropometric and biochemical measurements, as well as blood pressure parameters were available. Prevalence of overweight/obesity and related MS risk factors were analyzed across different body mass index (BMI) categories. The sensitivity and specificity of the WGOC cut-offs were compared with those of National Central Health Statistics (NCHS). RESULTS: Significantly high prevalence of MS and its components were found both in the obesity and overweight groups, which were classified by the WGOC and NCHS references. Similar distribution pattern of MS risk factors existed among different BMI categories, but the frequency and clustering of these factors in the obesity group classified by the NCHS were much higher. Owing to its irrelevant high cut-offs for overweight/obesity (especially for girls since the mid- adolescence), the NCHS reference had a high specificity but a low sensitivity. By contrast, the WGOC reference with a high sensitivity (90.1% for boys and 89.2% for girls) and a relative high specificity (96.4% and 92.8% for obese boys and girls, 78.1% and 68.9% for overweight boys and girls respectively) was more suitable to support the need for early screening, intervention, and treatment of childhood obesity in China. CONCLUSION: High sensitivity is more important than specificity in choosing appropriate screening tools for childhood obesity. Validity test demonstrates that it is rational to use the WGOC reference, established on the basis of the Chinese own reference population as a uniform screening tool for childhood obesity, which can effectively overcome the unnecessary treatment and psychosocial implications of stigmatization caused by misclassification.

Prevalence of the metabolic syndrome in secondary school adolescents in Beijing, China.

AIM: To estimate the prevalence and distribution of the metabolic syndrome and to determine the risk factors associated with the metabolic syndrome in secondary school adolescents. METHODS: In 2006, we conducted a school-based survey in Beijing, China. Questionnaire data, anthropometric, blood pressure, and biochemical measurements were available for 2020 adolescents aged 14-16 years. The metabolic syndrome was assessed using the National Cholesterol Education Program's (NCEP) Adult Treatment Panel (ATP) criteria modified for age. RESULTS: The overall prevalence of the metabolic syndrome among adolescents was 3.3%. In Beijing, 4.2% of boys and 2.5% of girls were affected (p<0.05). The syndrome was present in 28.1% of obese adolescents compared with 6.0% of overweight and 0.2% of normal status (p<0.001). Abdominal obesity and elevated blood pressure were the most common components of the metabolic syndrome in boys, and elevated triglyceride (TG) and abdominal obesity were the most common in girls. The prevalence of the metabolic syndrome was influenced by body mass index (BMI) status, father's educational degree and pubertal development. CONCLUSION: The metabolic syndrome and its components are frequent in overweight and obese adolescents in Beijing. Early identification and treatment of these risk factors may help target intervention to improve future cardiovascular health.

Study of the effects of mild hypothermia on cerebral PO2, PCO2 and pH and body temperature in patients with acute severe head injury.

OBJECTIVE: To study the effects of mild hypothermia on cerebral oxygen partial pressure, carbon dioxide partial pressure, pH and body temperature (PbrO2, PbrCO2, pHbr and BT) in patients with acute severe head injury. METHODS: Thirty-eight patients with acute severe head injury were treated with mild hypothermia, meantime PbrO2, PbrCO2, pHbr and BT were monitored in order to study the changes of PbrO2, PbrCO2, pHbr and BT. RESULTS: In patients with acute head injury, mild hypothermia obviously increased PbrO2, decreased PbrCO2 and CO2 accumulation and acidosis in brain tissue. BT was 1-1.5 deg. higher than rectal temperature (RT) after injury. The BT and RT were decreased when the patients were treated with mild hypothermia, but at the same time the difference between BT and RT was increased. CONCLUSIONS: In patients with acute severe head injury the direct monitoring of PbrO2, PbrCO2, pHbr and BT was safe and reliable, and is helpful in estimating prognosis and mild hypothermia therapy.