High magnetization FeCo nanoparticles for magnetorheological fluids with enhanced response.

We present results concerning the fabrication of a new magnetorheological fluid with FeCo magnetic nanoparticles (NPs) as magnetic fillers. These NPs have been fabricated by using the chemical reduction technique and show a pure crystalline phase with size ranging among 30-50 nm and high magnetization, 212 ± 2 A m2 kg-1. They agglomerate due to the strong magnetic dipolar interaction among them. These FeCo nanoparticles were used to synthesize a magnetorheological fluid by using oleic acid as surfactant, mineral oil as carrier liquid and Aerosil 300 as additive to control the viscosity of the fluid. The synthesized fluid showed a strong magnetorheological response with increasing shear stress values as the magnetic field intensity increases. Thus, we have measured a superior performance up to 616.7 kA m-1, with a yield stress value of 2729 Pa, and good reversibility after demagnetization process. This value competes with the best ones reported in the most recent literature. We have compared the obtained results with our previous reported ones by using high magnetization Fe NPs fabricated by the electrical explosion of wire method (Fe-EEW).

Validation of the Child Feeding Questionnaire in Spanish Parents of Schoolchildren.

OBJECTIVE: To test the reliability and factorial validity of the Child Feeding Questionnaire (CFQ) within a Spanish sample. DESIGN: Cross-sectional study. SETTING: All schools in a Spanish Mediterranean city of about 100,000 inhabitants. PARTICIPANTS: From a potential population of 1,623 children (mean age, 8.5 years), 960 parents (459 fathers and 501 mothers) of 515 children participated (32% response). MAIN OUTCOME MEASURE(S): The Spanish version of the CFQ was completed by both parents. Body mass index of the children was obtained from measured heights and weights. Parents reported their anthropometric and employment data. ANALYSIS: Reliability was assessed using Cronbach α. Factorial validity was examined by Procrustes semi-confirmatory factor and confirmatory factor analyses. RESULTS: Seven major factors with loadings similar to those in the original questionnaire were found: perceived responsibility, perceived parent weight, perceived child weight, concern about child weight (CN), pressure to eat (PE), monitoring, and restriction. Reliability was adequate for each factor and overall CFQ (α = .86). Goodness of fit indexes for confirmatory factor analysis solutions was acceptable. Item loadings ranged from 0.30 to 0.92. The factor of CN was associated with restriction [multivariate coefficient (R(2)) = 0.14; P < .001] and PE (R(2) = 0.36; P< .001). Child's body mass index showed a negative association with PE (R(2) = 0.11; P < .001) and a positive association with CN (R(2) = 0.25; P < .001) and factors related to feeding control (monitoring and restriction, R(2) = 0.04 and R(2) = 0.09, respectively; P < .001). CONCLUSIONS AND IMPLICATIONS: Results support the reliability and validity of the CFQ for a Spanish population, allowing for comparisons across cultures. The CFQ may be useful to identify parental feeding attitudes that can contribute to preventing risky eating behaviors in their children.

Being overweight or obese is associated with inhibition control in children from six to ten years of age.

AIM: This study investigated the relationship between being overweight or obese and executive function in six- to ten-year-olds. METHODS: The participants were 515 children (250 boys) from schools in Reus, Spain. The initial sample was measured and weighed and assessed with the Children's Color Trail Test. Children classified as overweight, including obese, and their age- and gender-matched controls (n = 221), were assessed in a second phase with the Five Digit Test (FDT) and the Symbol Digit Modalities Test. Logistic regression models were applied to analyse the effect of executive functions on being overweight, including obese. RESULTS: We found that 28.9% of the children were overweight and 7.2% were obese. The FDT showed that inhibition (odds risk of 1.04, range 1.00-1.08, p = 0.04) and flexibility (odds risk of 1.04, range 1.00-1.07, p = 0.02) were significantly associated with overweight, including obesity, regardless of sociodemographic and psychopathological variables. CONCLUSION: These results suggest that children who were overweight or obese had a reduced ability to mobilise the cognitive effort required to inhibit involuntary responses and to switch between different mental operations. A developmental trajectory would provide important insights into the relationship between executive functioning pattern and the risk of being overweight or obese.