Sintesis Polianilin yang Diperkaya γ-Fe2o3 dari Pasir Besi Lokal Sulawesi Tenggara untuk Aplikasi

This research is aimed to develop the radar absorbing material based on polyaniline enriched by γ-Fe2O3 synthetized from the sandstone. γ-Fe2O3 is, then, derived from calcination process of Fe3O4 powder at the temperature of 400-600oC. Fe3O4 powder itself is extracted from the local sandstone of South East Sulawesi area by using the co-precitipation method with both HCl and NH4OH act as the solvent and precitipation agent, respectively. The polyaniline is synthetized from its monomer, aniline, where both HCl and NH4OH are also used as a dopant and an oxydator agent, respectively. Effect of reaction pH on the crystal size of Fe3O4 is also investigated. The XRD spectrum shows that a rather high purity of Fe3O4 in nano size is being achieved at the pH value of 8 and 9. However, at a rather low pH value (6.5 and 7.5), the additional weak peaks in XRD spectrum shows the existence other metal compounds impurity. The crystal sizes is approximately ~8.01 and 11.07 nm for pH value of 8 and 9. The VSM measurement result shows that the saturated magnetization value of Fe3O4 is 24.45 emu/g. The Fe3O4 is calcined at temperature of 500oC for 3 hours to get γ-Fe2O3. Finally, the polyaniline-γ-Fe2O3 composites were synthetized using an insitu polymerization method where the weight contents of γ-Fe2O3 are 5, 10, 15, and 20 percent. Those materials will be useful as a prospective application in radar absorbing materials technology at frequency ranges of 9-17 GHz

The dimerization domain of LFB1/HNF1 related transcription factors: A hidden four helix bundle?

LFB1/HNF1 alpha and LFB3/HNF1 beta bind DNA as dimers and form heterodimers together in vivo and in vitro. The dimerization domain has been located in both proteins in the 32 N-terminal residues. In previous papers we have described the conformational stability as determined by CD and the secondary structure by NMR studies of a peptide with the amino acid sequence of the dimerization domain of LFB1/HNF1 alpha. This study presents a more complete characterization of similar synthetic peptides spanning the LFB3/HNF1 beta dimerization domain and the alpha/beta heterodimer. The HNF1 peptides represent an example of structures which cannot be determined by NOE data alone because they are not sufficient to define one unique solution. An approach is presented which combines NMR data, the protein structure database and structural analyses according to known principles of protein structure. On this basis we are able to determine possible solutions and to identify a four helix bundle as the structure most consistent with the experimental evidence

Selective interaction of glycosomal enzymes from Trypanosoma brucei with hydrophobic cyclic hexapeptides.

Hydrophobic cyclic hexapeptides have been reported to selectively inhibit glycosomal triosephosphate isomerase from Trypanosoma brucei (Kuntz et al, 1992, Eur. J. Biochem., 207, 441-447). Here it is shown that this inhibition is not due to a specific interaction between the enzyme and soluble hydrophobic cyclic hexapeptides, but that it is the result of a coprecipitation of trypanosome triosephosphate isomerase with cyclic hexapeptides when the solubilities of the latter are exceeded. A study of the interaction of these hexapeptides with other glycosomal enzymes revealed that several of them, such as phosphoglycerate kinase and hexokinase, also coprecipitated with these peptides, whereas most of the homologous enzymes from other organisms did not coprecipitate, nor were they inactivated

The Performance of Wisconsin Retail and Service Markets

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