8,387 research outputs found

    Modifying the hydrophobic nature of MAF-6

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    Using a combination of molecular simulations techniques, we evaluate the structural tunability of the metal azolate framework with zeolitic RHO topology, MAF-6. Two mechanisms are explored to induce hydrophilicity to this hydrophobic material. The study at a molecular level of water adsorption takes place under a variety of conditions. On a first step, we consider water mixtures containing benzene or alcohols, paying special attention to the effect of the size of the alcohol molecules. On a second approach, we analyse the effect of small weight percentages of salt into the MAF-6 on the water adsorption. We first validate the accuracy of the host–guest interactions by reproducing experimental data. A new set of Lennard-Jones parameters for the interaction water- MAF-6 is also provided. The water adsorption behaviour of MAF-6 is studied in terms of adsorption isotherms, heats of adsorption, radial distribution functions, hydrogen bonds formation, and water distribution inside the material. We found that the presence of long molecules of alcohols favours the water adsorption at low values of pressure by smoothing the phase transition of water withing the MAF-6. On the other hand the addition of salt to the structure creates additional adsorption sites for water enhancing its adsorption, while reducing the saturation capacity of the material since the presence of salt reduces the accessible pore volume

    Mali : Interessen, Intrigen, Interventionen

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    Volume: 71Start Page: 27End Page: 4

    Low birth weight and small for gestational age are associated with complications of childhood and adolescence obesity: systematic review and meta-analysis

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    In recent decades, the incidence of type 2 diabetes (T2D) has increased dramatically in children and adolescents, posing a real public health problem. Beyond unhealthy diets and sedentary lifestyles, growing evidence suggests that some perinatal factors, such as low birth weight (LBW), are associated with higher risk of T2D in adulthood. In this regard, it remains unclear whether the increased risk is already present in childhood and adolescence. We conducted a systematic review and meta-analysis to clarify the association of LBW or being small for gestational age (SGA) with insulin resistance in childhood and adolescence. The systematic review resulted in 28 individual studies, and those with the same outcome were included within two random-effects meta-analyses. Compared with children or adolescents born with adequate size for gestational age, those SGA had 2.33-fold higher risk of T2D (95% confidence interval [CI]: 1.05–5.17). Furthermore, LBW and being SGA were associated with 0.20 higher mean homeostasis model assessment of insulin resistance (HOMA-IR) values (95% CI: 0.02–0.38). Given the high prevalence of preterm babies, from a population perspective, these results may be of great importance as they point to the existence of a potentially vulnerable subgroup of children and adolescents that could benefit from screening tests and early preventive strategies

    Influence of parental healthy-eating attitudes and nutritional knowledge on nutritional adequacy and diet quality among preschoolers: the SENDO project

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    Parental nutrition knowledge and attitudes play a fundamental role in their children's food knowledge. However, little is known about their influence on their children's diet quality and micronutrient intake. Thus, we aimed to assess the association of parental nutrition knowledge and healthy-eating attitudes with their children's adherence to the Mediterranean dietary pattern and micronutrient adequacy. Parental healthy-eating attitudes and knowledge of the quality of their child's diet as well as anthropometric, lifestyle, and nutrient intake characteristics were recorded with a basal questionnaire that included a 140-item-food frequency-questionnaire. A total of 287 pre-school children were included in the analyses. Intake adequacy was defined using the Estimated Average Requirements (EAR) cut-off point method. We developed a parental nutrition knowledge and healthy-eating attitudes scores and evaluated whether they were independently associated with 1) children's inadequate intake (probability of failing to meet 3 EAR) of micronutrients, using logistic regression analyses, and 2) children's diet quality (adherence to the Mediterranean Diet according to a Mediterranean Diet Quality Index for children and adolescents, the KIDMED index), using multiple linear regression models. A higher score in the parental healthy-eating attitudes score was associated with lower risk of failing to meet 3 EAR compared with the reference category (odds ratio (OR): 0.3; 95% confidence interval (CI) 0.12-0.95; p for trend: 0.037) and a higher adherence to the Mediterranean diet in the most adjusted model ( coefficient: 0.34; 95% CI 0.01-0.67; p for trend: 0.045). Our results suggest a positive association of parental healthy-eating attitudes with nutritional adequacy and diet quality in a sample of Spanish preschoolers. Public health strategies should focus on encouraging parental healthy-eating attitudes rather than simply educating parents on what to feed their children, recognizing the important influence of parental behavior on children's practices

    Searching for dark-matter waves with PPTA and QUIJOTE pulsar polarimetry

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    The polarization of photons emitted by astrophysical sources might be altered as they travel through a dark matter medium composed of ultra light axion-like particles (ALPs). In particular, the coherent oscillations of the ALP background in the galactic halo induce a periodic change on the polarization of the electromagnetic radiation emitted by local sources such as pulsars. Building up on previous works, we develop a new, more robust, analysis based on the generalised Lomb-Scargle periodogram to search for this periodic signal in the emission of the Crab supernova remnant observed by the QUIJOTE MFI instrument and 20 galactic pulsars from the Parkes Pulsar Timing Array (PPTA) project. We also carefully take into account the stochastic nature of the axion field, an effect often overlooked in previous works. This refined analysis leads to the strongest limits on the axion-photon coupling for a wide range of dark matter masses spanning 10−23 eV≲ma≲10−19 eV10^{-23}\text{ eV}\lesssim m_a\lesssim10^{-19} \text{ eV}. Finally, we survey possible optimal targets and the potential sensitivity to axionic dark-matter in this mass range that could be achieved using pulsar polarimetry in the future
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