Micro-patterned Nafion membranes for direct methanol fuel cell applications

In this work, we report the direct methanol fuel cell (DMFC) performance of micro-patterned (μp) Nafion® 117 (N117) membranes prepared by hot embossing and compare them with that of normal N117 and heat and pressure treated (hp) N117 non-patterned (smooth) membranes.\ud \ud Our results suggest that the heat and pressure treatment during hot embossing probably makes the membrane structure more compact and decreases the membrane swelling due to decrease of amount of freezable water in the membrane. This leads to lower methanol flux for both hp N117 and μp N117 membranes in comparison to the non-patterned N117. Nonetheless, all three membranes have similar electrical resistance because they probably have the same amount of non-freezable water. Non-freezable water is the one which is strongly bound to the ionic groups and facilitates the proton transport and it is not influenced by the heat treatment.\ud \ud In the DMFC, the hp N117 has rather similar performance with normal N117 membrane despite its lower methanol crossover. The μp N117, however, has better performance than normal N117 probably due to better catalyst utilization by the micro-pattern. In DMFC stacks, which contain multiple MEAs, this can lead to a higher power output gain and/or lower system volume

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Analysis of [U-13C6]glucose in human plasma using liquid chromatography/isotope ratio mass spectrometry compared with two other mass spectrometry techniques

The use of stable isotope labelled glucose provides insight into glucose metabolism. The 13C-isotopic enrichment of glucose is usually measured by gas chromatography/mass spectrometry (GC/MS) or gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). However, in both techniques the samples must be derivatized prior to analysis, which makes sample preparation more labour-intensive and increases the uncertainty of the measured isotopic composition. A novel method for the determination of isotopic enrichment of glucose in human plasma using liquid chromatography/isotope ratio mass spectrometry (LC/IRMS) has been developed. Using this technique, for which hardly any sample preparation is needed, we showed that both the enrichment and the concentration could be measured with very high precision using only 20 µL of plasma. In addition, a comparison with GC/MS and GC/IRMS showed that the best performance was achieved with the LC/IRMS method making it the method of choice for the measurement of 13C-isotopic enrichment in plasma samples

Observational outcome results following a randomized controlled trial of early amino acid administration in preterm infants

Several reports have investigated amino acid administration in premature infants during the early postnatal phase. Most of these previous studies, however, have only evaluated short-term in-hospital outcomes. Our aim was to describe long-term outcomes in premature infants previously subjected to different nutritional regimens in a randomized controlled trial. The primary outcome was survival without major disabilities, and the secondary outcomes included anthropometry and mental development. Infants born <32 weeks' gestation and <1500 g were randomized to receive glucose (n = 69) or glucose with 2.4 g · kg(-1) · day(-1 amino acids) (n = 63) from birth. From postnatal day 3 onward, the nutritional intake was similar. At 2 years of corrected age, the surviving infants were assessed for neurodevelopmental outcome and anthropometry. Ninety-seven percent of the surviving infants were examined at follow-up, with no overall effect on survival without major disabilities. Boys, however, had a normal outcome significantly more often if amino acids were administered from birth onward (crude odds ratio 3.8, 95% confidence interval 1.3-11.4) and following adjustment for confounders (odds ratio 6.2, 95% confidence interval 1.0-38.0). The secondary outcomes exhibited no differences in anthropometric data. The mental developmental index was lower in the small number of girls who survived without major disabilities following the early administration of amino acids. In this hypothesis-generating outcome study, premature boys, but not girls, benefited from amino acid administration directly following birth. The observed lower mental developmental index in a subgroup of girls, however, warrants further studie