Experimental solid–liquid equilibria and solid formation kinetics for carbon dioxide in methane for LNG processing

In cryogenic liquefaction processes, CO₂ poses a solid-formation risk even in trace concentrations. We present solid–fluid equilibrium (SFE) data for CO₂ in liquid methane at CO₂ concentrations from (52 to 500) ppm, extending the available data and indicating that models tuned to existing data over predict the solubility of CO₂ at LNG storage temperatures (~112 K) by nearly a factor of 3. The new data are used to improve the SFE model in the ThermoFAST software package. The formation kinetics of CO₂ solids in liquid methane are elucidated at conditions relevant to cryogenic gas processing. Repeated, ramped-temperature formation measurements provide a statistical basis for quantifying solidification risk. Nucleation rates extracted from the ramped-temperature data, consistent with those measured at fixed temperature, were used to extract parameters describing CO₂ solid formation in methane. These results significantly improve the ability to predict CO₂ solid formation risk in cryogenic natural gas processing.     

The drying shrinkage of cellulosic fibres and isotropic paper sheets

We present theory for the shrinkage on drying of the cross-sectional area of cellulosic fibres and show that this depends on their initial moisture content only. For the linear shrinkage of cross-sectional dimensions, an additional parameter is required, which we estimate from comparison of the theory with experimental data from the literature. We proceed to combine our model of fibre shrinkage with probabilistic theory for fibre contacts in random fibrous networks to obtain a model for the unrestrained shrinkage of isotropic paper sheets. The expression obtained depends only on the moisture content of fibres and the extent of inter-fibre contact and exhibits good agreement with experimental data for laboratory-formed paper sheets. The results have relevance to the commercial manufacture of paper and potential for application to the study of cellulose nano-composites.     

A novel isoform of the mitochondrial outer membrane protein VDAC3 via alternative splicing of a 3-base exon. Functional characteristics and subcellular localization

Voltage-dependent anion channels (VDACs) are pore-forming proteins found in the outer mitochondrial membrane of all eucaryotes. VDACs are the major pathway for metabolites through the outer mitochondrial membrane and, in mammals, bind several cytosolic carbohydrate kinases. Whereas yeast contain a single VDAC (YVDAC), to date three isoforms have been described in the mouse that constitute a gene family. We have observed an additional isoform of VDAC3 that appears to be generated via the tissue-specific alternative splicing of a 3-base exon (ATG). The exon is predicted to introduce a methionine 39 amino acids downstream of the amino terminus of the polypeptide. Between exons 3 and 4 is an intronic sequence that potentially encodes the exon, with flanking splice enhancer elements. Expression of this alternative form in the mouse is limited to brain, heart, and skeletal muscle. Complementation of YVDAC-deficient yeast by the two isoforms and with other sequence variants of VDAC3 suggests this residue is an important modulator of VDAC3 function. In transfected mammalian cells both isoforms localize to mitochondria. A similar variant is present in humans.