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To examine the associations between serum 25-hydroxyvitamin D (25(OH)D) levels and serum liver enzymes in a representative sample of US adults.
The cross-sectional study sample consisted of 24 229 adults with data on serum 25(OH)D levels and serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP) and gamma-glutamyl transaminase (GGT) concentrations, in addition to data on other potential confounders. Multivariate logistic regression and linear regression were applied to assess the associations between serum 25(OH)D levels and ALT, AST, ALP and GGT concentrations.
The National Health and Nutrition Examination Survey, 2001–2006.
The cross-sectional study sample consisted of 24 229 adults.
We found a significant association between low serum 25(OH)D levels (<30 nmol/l) and ALP levels in all participants (OR 2·67; 95 % CI 1·98, 3·59; P < 0·001), a confirmed healthy population (OR 3·02; 95 % CI 2·25, 4·07; P < 0·001) and individuals with viral hepatitis (OR 2·87; 95 % CI 1·52, 5·44; P = 0·006) compared with those who had normal 25(OH)D levels (>50 nmol/l). Moreover, in both the logistic regression and linear regression, the associations between 25(OH)D levels and ALP levels were stronger in the subgroups with obesity. No association was present between ALT, AST or GGT levels and serum 25(OH)D levels in this population.
The results of the present study provide epidemiological evidence that vitamin D deficiency is associated with liver ALP levels in humans. This finding suggests a potential adverse effect of low 25(OH)D levels on human liver function. However, the underlying mechanisms still need further investigation.
Our experiments show that external focusing and initial laser energy strongly influences filament generated by the femtosecond Ti–sapphire laser in air. The experimental measurements show the filament length can be extended both by increasing the laser energy and focal length of focusing lens. On the other hand, the plasma fluorescence emission can be enhanced by increasing the laser energy with fixed focal length or decreasing the focal length. In addition, the collapse distance measured experimentally are larger than the calculated ones owing to the group-velocity-dispersion effect. In addition, we find that the line widths of the spectral lines from
is independent of filament positions, laser energies and external focusing.
In this paper, the effect of an annealing treatment on the microstructure, mechanical
properties and electrical conductivity of a deformed Cu-12.8 wt%Fe composite prepared by
the “casting/cold working” process is investigated. The Fe filaments exhibit the shape
characteristic in the as-drawn composite as the annealing temperature is lower than 500
°C. When the annealing temperature is above 500 °C, the Fe filaments undergo the
instability process in terms of boundary splitting, coarsening and breakup gradually. The
tensile strength gradually decreases with increasing annealing temperature due to the
coarsening of filament spacing. The work hardening for the composite annealed above 600 °C
is slower than that annealed at a lower temperature. The electrical conductivity reaches a
maximum of 60%IACS at a temperature of 450 °C for one hour of annealing, and it further
increases with increasing annealing time at 450 °C to reach a plateau of 68% IACS. The
curve between the tensile strength and electrical conductivity under different annealing
processes indicates that the optimum annealing temperature for the Cu-Fe composite is 450
We use weakly nonlinear analysis via a two-parameter expansion to study bifurcation of conduction into cellular convection of an internally heated fluid in a porous medium that forms a horizontal layer between two isothermal walls. The Darcy–Boussinesq model of convection is enhanced by including two nonlinear terms: (i) quadratic (Forchheimer) drag; and (ii) hydrodynamic dispersion enhancement of the thermal conductivity described by a weak linear relationship between effective conductivity and local amplitude of filtration velocity. The impact of the second term on the shape of the bifurcation curve for two-dimensional rolls is profound in the presence of uniform volumetric heating. The resulting bifurcation structure is unlike any pitchfork bifurcations typical of the classical Bénard problem. Although direct experimental validation of the novel bifurcation is not available, we would like to register it as an alternative or a supplement to models of small imperfections, and as an attempt to account for the scatter of observed critical values for the first bifurcation.
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