Metallic sample preparation for phase transformation analysis.

Metallic materials characterization is a important part of phase transformation studies, and the sample preparation plays a crucial role in the measured properties. The methodologies available are not fully described and refer in its majority only to iron-based and aluminum-based alloys focusing in industrial analysis. In this paper the authors fully described the preparation methodology for metallic samples used by their research group. This method aims to attend different characterization techniques, producing samples of complex metallic systems from pure base materials by arc melting. •The melting of metallic ingots from pure base materials was fully described.•The correct sample cutting, sanding and polishing procedures were described.•A full detailed procedure is described to prepare the samples for different analyses.

The role of apolipoprotein N-acyl transferase, Lnt, in the lipidation of factor H binding protein of Neisseria meningitidis strain MC58 and its potential as a drug target.

BACKGROUND AND PURPOSE: The level of cell surface expression of the meningococcal vaccine antigen, Factor H binding protein (FHbp) varies between and within strains and this limits the breadth of strains that can be targeted by FHbp-based vaccines. The molecular pathway controlling expression of FHbp at the cell surface, including its lipidation, sorting to the outer membrane and export, and the potential regulation of this pathway have not been investigated until now. This knowledge will aid our evaluation of FHbp vaccines. EXPERIMENTAL APPROACH: A meningococcal transposon library was screened by whole cell immuno-dot blotting using an anti-FHbp antibody to identify a mutant with reduced binding and the disrupted gene was determined. KEY RESULTS: In a mutant with markedly reduced binding, the transposon was located in the lnt gene which encodes apolipoprotein N-acyl transferase, Lnt, responsible for the addition of the third fatty acid to apolipoproteins prior to their sorting to the outer membrane. We provide data indicating that in the Lnt mutant, FHbp is diacylated and its expression within the cell is reduced 10 fold, partly due to inhibition of transcription. Furthermore the Lnt mutant showed 64 fold and 16 fold increase in susceptibility to rifampicin and ciprofloxacin respectively. CONCLUSION AND IMPLICATIONS: We speculate that the inefficient sorting of diacylated FHbp in the meningococcus results in its accumulation in the periplasm inducing an envelope stress response to down-regulate its expression. We propose Lnt as a potential novel drug target for combination therapy with antibiotics. LINKED ARTICLES: This article is part of a themed section on Drug Metabolism and Antibiotic Resistance in Micro-organisms. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.14/issuetoc.

Nature of vibrational coupling in helical peptides: an isotopic labeling study.

Infrared (IR) and vibrational circular dichroism (VCD) spectra were measured for a series of isotopically ((13)C on two or more amide Cdouble bond]O) labeled, 25 residue, alpha-helical peptides of the sequence Ac-(AAAAK)(4)AAAAY-NH(2) that were also studied in the previous paper. Theoretical IR and VCD simulations were performed for correspondingly isotopically labeled Ac-A(24)-NHCH(3) constrained to an alpha-helical conformation by use of property tensor transfer from density functional theory (DFT) calculations on Ac-A(10)-NHCH(3). The simulations predicted and experiments confirmed that the vibrational coupling constants between i, i + 1 and i, i + 2 residues differ in sign, thus leading to a reversal of the (13)C VCD pattern and explaining the large shift in the (13)C amide I frequency as reported in the previous paper. The sign of the coupling constant remained consistent for larger label separation (with the exception of i, i + 4) and for more labels with uniform separation. Such effects confirm that the isotopically labeled group vibrations are essentially only coupled to each other and are effectively uncoupled from those of the unlabeled groups. This development confirms the utility of isotopic labels for site-specific structural studies with vibrational spectra. Observed spectral effects cannot be explained by considering only transition dipole coupling (TDC) between amide oscillators, particularly for smaller label separations, but the TDC and ab initio predicted couplings roughly converge at large separation.

Características do leite fluido consumido em Belém, Pará / Characteristics of fluid milk distributed for consumptiom in Belém, Brazil

Empregando-se métodos físico-químicos oficiais foram determinadas algumas características do leite fluido consumido em Belém, Estado do Pará, observando-se flagrantes irregularidades nos três tipos de apresentaçäo do produto em relaçäo aos padröes regulamentares. No leite cru, 24 (39,4 por cento) amostras apresentaram densidade abaixo do limite regulamentar, 10 (15,9 por cento) e 34 (54,0 por cento) amostras tinham acidez titulável respectivamente abaixo e acima da faixa regulamentar, 17 (42,5 por cento) mostraram instabilidade frente ao álcool-alizarol, 31 (83,8 por cento) apresentavam sujidades, seis (9,8 por cento) continham peróxido de hidrogênio e 21 (32,3 por cento) foram classificadas como de péssima qualidade na prova da redutase. O leite pasteurizado reconstituído com 3 por cento de gordura apresentou 23 (95,8 por cento) amostras com densidade abaixo do limite regulamentar, 19 (67,9 por cento) e três (10,7 por cento) com acidez titulável respectivamente abaixo e acima do limite regulamentar, cinco (16,1 por cento) continham peróxido de hidrogênio e 25 (86,2 por cento) mostraram superaquecimento no teste de peroxidase. No leite pasteurizado tipo "C", duas (33,3 por cento) amostras tinham acidez titulável acima do limite regulamentar e 100 por cento delas mostraram superaquecimento no teste de peroxidase