Study of Mycoplasma mycoides subsp. Mycoides exopolysaccharides

Mycoplasma mycoides subsp. mycoides (Mmm) is responsible for contagious bovine pleuropneumonia, a severe lung disease of cattle and buffaloes. Mmm belongs to the class Mollicutes, grouping wall-less bacteria that have evolved by major gene losses and are considered the smallest self-replicating organisms. Mmm cells are known to be surrounded by a galactan pseudo-capsule, which has been associated to Mmm pathogenicity. Mmm is also able to secrete free exopolysaccharides (EPS) both in vitro and in vivo. However, these EPS have not been characterized yet because of technical difficulties due to the complexity of the mycoplasma growth medium

SYNTHESIS AND CHARACTERIZATION OF POLYIMIDEZEOLITE MIXED MATRIX MEMBRANE FOR BIOGAS PURIFICATION

Biogas has become an attractive alternative energy source due to the limitation of energy from fossil. In this study, a new type of mixed matrix membrane (MMM) consisting of polyimide-zeolite was synthesized and characterized for biogas purification. The MMM consists of medium concentration of polymer (20% wt polyimide), 80% N-Methyl-2-pyrrolidone (NMP) and 25% zeolite 4A in total solid were prepared by a dry/wet phase inversion technique. The fabricated MMM was characterized using SEM, DSC, TGA and gas permeation. Post treatment coating procedure was also conducted. The research showed that surface coating by 3% silicone rubber toward MMM PI 20% gave the significant effect to improve membrane selectivity. The ideal selectivity for CO2/CH4 separation increased from 0.99 for before coating to 7.9 after coating for PI-Zeolite MMM, respectively. The results suggest that PI-Zeolite MMM with good post treatment procedure will increase the membrane selectivity and permeability with more saver polymer requirement as well as energy saving due to low energy for mixing

Facilitated transport effect of Ag+ ion exchanged halloysite nanotubes on the performance of polyetherimide mixed matrix membrane for gas separation

This study investigated the facilitated transport effect of Ag+ ion exchanged halloysite nanotubes (HNTs) as filler on the gas separation performance of asymmetric mixed matrix membranes (MMMs). The polymer matrix employed in this study was commercial polyetherimide (PEI) Ultem 1000. The modified HNTs were prepared by treating HNTs with N-ß-(aminoethyl)-?-aminopropyltrimethoxy silane (AEAPTMS) and silver nitrate. FESEM, XRD, FTIR, TGA, DSC, EDX and pure gas permeation testing were used to characterise the modified HNTs and the fabricated MMMs. Three protocols were performed: (i) S-HNT MMM (no Ag+ ion exchange treatment), (ii) S-Ag-HNT MMM (first Ag+ ion exchanging and then silylation of HNTs), and (iii) Ag-S-HNT MMM (first silylation and then Ag+ ion exchanging of HNTs). FTIR and TGA showed that silylation occurred successfully. From XRD we found out that, the Ag+ ion exchanging did not affect the HNT crystalline structure. EDX revealed that, Ag+ ion exchanging after silylation of HNTs resulted in much higher concentration of Ag+ ions in the Ag-S-HNT product. This in turn showed that AEAPTMS could successfully enhance the HNTs cation exchange capacity (CEC), which resulted in higher concentration of Ag+ ions in the modified HNTs. DSC disclosed depression in the glass transition temperature (Tg) of MMMs possessed Ag+ ions. Three major factors were discussed: (i) facilitated transport affect of Ag+ ions, (ii) Knudsen diffusion and (iii) Tg depression. By increasing the fillers loading, all of the factors exhibited an additive influence on the permeability. The order of closeness of the resultant MMMs to the ideal morphology was as follows: Ag-S-HNT MMM > S-Ag-HNT MMM > S-HNT MMM. Ag-S-HNT MMM exhibited outstanding performance among the three protocols

Can extra dimensions accessible to the SM explain the recent measurement of anomalous magnetic moment of the muon?

We investigate whether models with flat extra dimensions in which SM fields propagate can give a significant contribution to the anomalous magnetic moment of the muon (MMM). In models with only SM gauge and Higgs fields in the bulk, the contribution to the MMM from Kaluza-Klein (KK) excitations of gauge bosons is very small. This is due to the constraint on the size of the extra dimensions from tree-level effects of KK excitations of gauge bosons on precision electroweak observables such as Fermi constant. If the quarks and leptons are also allowed to propagate in the (same) bulk (``universal'' extra dimensions), then there are no contributions to precision electroweak observables at tree-level. However, in this case, the constraint from one-loop contribution of KK excitations of (mainly) the top quark to T parameter again implies that the contribution to the MMM is small. We show that in models with leptons, electroweak gauge and Higgs fields propagating in the (same) bulk, but with quarks and gluon propagating in a sub-space of this bulk, both the above constraints can be relaxed. However, with only one Higgs doublet, the constraint from the process b -> s gamma requires the contribution to the MMM to be smaller than the SM electroweak correction. This constraint can be relaxed in models with more than one Higgs doublet.Comment: Latex, 11 pages, 1 ps fig. included. In the revised version, a reference has been added. Version to be published in Phys. Lett.