Objective Maintaining muscle function throughout life is critical for healthy ageing. Although in-vitro studies consistently indicate beneficial effects of 25-hydroxyvitamin D (25-OHD) on muscle function, findings from population-based studies remain inconclusive. We therefore aimed to examine the association between 25-OHD concentration and handgrip strength across a wide age range, and assess potential modifying effects of age, sex and season. Methods We analysed cross-sectional baseline data of 2,576 eligible participants out of the first 3,000 participants (recruited from March 2016 to March 2019) of the Rhineland Study, a community-based cohort study in Bonn, Germany. Multivariate linear regression models were used to assess the relation between 25-OHD levels and grip strength, while adjusting for age, sex, education, smoking, season, body mass index, physical activity levels, osteoporosis and vitamin D supplementation. Results Compared to participants with deficient 25-OHD levels (<30 nmol/L), grip strength was higher in those with inadequate (30 to <50 nmol/L) and adequate (≥50 to ≤125 nmol/L) levels (ßinadequate=1.222 [95%CI: 0.377; 2.067], p=0.005; ßadequate=1.228 [95%CI: 0.437; 2.019], p=0.002). Modeling on a continuous scale revealed grip strength to increase with higher 25-OHD levels up to ~100 nmol/L, after which the direction reversed (ßlinear=0.505, [95%CI: 0.179; 0.830], p=0.002; ßquadratic=-0.153 [95%CI: -0.269; -0.038], p=0.009). Older adults showed weaker effects of 25-OHD levels on grip strength than younger adults (ß25OHDxAge=-0.309, [95%CI: -0.594; -0.024], p=0.033). Conclusions Our findings highlight the importance of sufficient 25-OHD levels for optimal muscle function across the adult lifespan. However, vitamin D supplementation should be closely monitored to avoid detrimental effects.

Abstract. Using the diffusion couple technique, diffusion of CO2 in a leucititic melt from the Colli Albani Volcanic District in Italy was investigated at temperatures between 1200 and 1350 ∘C in an internally heated pressure vessel at 300 MPa. To examine the effect of dissolved H2O in the melt, experiments were performed for a nominally dry melt (0.18 ± 0.03 wt % H2O) and for a hydrous melt containing 3.36 ± 0.28 wt % H2O. Diffusion experiments were run for 40 to 120 min and terminated by rapid quench. CO2 concentration profiles were subsequently measured via attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and fitted with error functions to obtain individual diffusion coefficients. For the anhydrous and hydrous sample series, seven diffusion coefficients were determined each. Diffusivity was found to increase exponentially with temperature for both melts following an Arrhenius behaviour. The Arrhenius equation for the nominally dry leucititic melt is described by log⁡DCO2=-1.44(±0.24)⋅10000T-1.95(±1.59), where DCO2 is the diffusion coefficient in m2 s−1 and T is the temperature in K. In the experimental temperature range, H2O has an accelerating effect on CO2 diffusion. At 1200 ∘C, diffusivity increases from 1.94 × 10−12 m2 s−1 in the dry melt to 1.54 × 10−11 m2 s−1 in the hydrous melt. The Arrhenius equation for the leucititic melt containing 3.36±0.28 wt % H2O is given by log⁡DCO2=-1.09(±0.30)⋅10000T-3.41(±1.99). The activation energies for CO2 were determined to be 275 ± 47 kJ mol−1 for the anhydrous melt and 209 ± 58 kJ mol−1 for the hydrous melt. The high CO2 activation energy in the leucititic melt indicates that the diffusion might be partly attributed to the carbonate species. At high magmatic temperatures above 1200 ∘C, CO2 diffusivity in the leucititic melt is only slightly lower than CO2 diffusion in rhyolitic and basaltic melts, suggesting that CO2 diffusion in natural melts is relatively independent from the bulk melt composition at such temperatures. CO2 diffuses slower than other volatile components such as halogens and H2O in depolymerized silicate melts. Thus, a fractionation of volatiles can occur during magma ascent and degassing. The experimental data on CO2 diffusion can be used for modelling the degassing mechanisms of ultrapotassic mafic melts.

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Desde la Ilustración, las consideraciones en torno a la reflexión se hicieron ex negativo, describiendo sus condicionantes. Al abordar la reflexión en el aprendizaje de lenguas extranjeras, por tanto, no se pueden aplicar las definiciones filosóficas sin preguntarse cuáles son sus condicionantes específicos. En esta contribución se describen tres condicionantes de la reflexión para el aprendizaje de lenguas: 1. La sobrecarga cognitiva lingüística, acompañada del miedo específico a hablar la L2, puede inhibir y frustrar la reflexión en las fases de interlengua; 2. La dificultad de modificar hábitos de aprendizaje relacionados con la propia autoorganización y autopercepción puede frenar o bloquear la reflexión en el aprendizaje; 3. Sin una práctica reflexiva del profesorado será difícil superar ambos condicionantes, pero si se superan, el aprendizaje de lenguas extranjeras probablemente contribuirá a una educación que promueve una reflexión crítica con las creencias de la propia cultura.