A.O. dos Santos

Hepatitis Delta virus genotype 8 infection in Northeast Brazil: Inheritance from African slaves?

Hepatitis Delta virus (HDV) is endemic worldwide, but its prevalence varies in different geographical areas. While in the Brazilian Amazon, HDV is known to be endemic and to represent a significant public health problem, few studies have assessed its prevalence in other regions in the country. This study evaluated the seroprevalence of HDV among HBsAg chronic carriers from Maranhão state, a region located in the Northeast of Brazil. Among 133 patients, 5 had anti-HD, of whom 3 had HDV RNA. HDV genotypes were characterized by Bayesian phylogenetic analysis of nucleotide sequences from the HDAg coding region. HDV-3 was identified in one patient who lives in Maranhão, but was born in Amazonas state (Western Amazon basin). Phylogenetic analysis shows that this HDV-3 sequence grouped with other HDV-3 sequences isolated in this state, which suggests that the patient probably contracted HDV infection there. Surprisingly, the other two patients were infected with HDV-8, an African genotype. These patients were born and have always lived in Urbano Santos, a rural county of Maranhão state, moreover they had never been to Africa and denied any contact with people from that continent. This is the first description of the HDV-8 in non-native African populations. This genotype may have been introduced to Brazil through the slaves brought to the country from the West Africa regions during the 16-18th centuries. Our results indicate that the need of clinical and epidemiological studies to investigate the presence of this infection in other areas in Brazil.

Study of the magnetocaloric properties of the antiferromagnetic compounds RGa2 (R = Ce, Pr, Nd, Dy, Ho and Er).

Magnetocaloric properties of antiferromagnetic RGa(2) (R = Ce, Pr, Nd, Dy, Ho and Er) compounds have been reported. These systems present an antiferromagnetic transition below 15 K and a field induced metamagnetic transition from the antiferromagnetic to ferromagnetic state. Our results show that the character of the magnetic field induced transition along the series affects the magnetocaloric properties. For the compounds with R = Ho, Dy and Er both negative and positive magnetocaloric effect (MCE) were observed above μ(0)ΔH = 2 T where the rate between negative and positive MCE contributions depends on how the magnetic transitions occur in these compounds. The evaluated values of maximum magnetocaloric properties of RGa(2) compounds are similar to other potential magnetic refrigerant materials reported in the literature.

High pressure Raman spectra of monoglycine nitrate single crystal.

Single crystal of monoglycine nitrate has been studied by Raman spectroscopy under high pressures up to 5.5 GPa. The results show changes in lattice modes in the pressure ranges of 1.1-1.6 GPa and 4.0-4.6 GPa. The first change occurs with appearance of bands related to the lattice modes as well as discontinuity in the slope of dΩ/dP of these modes. Moreover, bands associated with the skeleton of glycine suggest that the molecule undergoes conformational modifications. The appearance of a strong band at 55 cm(-1) point to a second phase transition associated with the lattice modes, while the internal modes remain unchanged. These anomalies are probably due to rearrangement of hydrogen bonds. Additionally, decompression to ambient pressure shows that the phase transitions are reversible. Finally, the results show that the nitrate anions play an important role on the stability of the monoglycine nitrate crystal.

Low-temperature Raman spectra of the 2-(α-methylbenzylamino)-5-nitropyridine crystal

The polar organic 2-(α-methylbenzylamino)-5-nitropyridine crystal (MBANP) has been studied by Raman spectroscopy at low temperatures (from 300 to 10K). The effect of temperature change on the vibrational spectrum is discussed with the aid of DFT calculations. The behavior of the Raman spectra indicates that MBANP molecules present a different conformation at low temperatures associated with the rotation of the phenyl and pyridine rings. Temperature-dependent X-ray measurements and differential scanning calorimetry (DSC) analysis were utilized as complementary techniques to investigate the structural stability of MBANP crystal.

KDP:Mn piezoelectric coefficients obtained by X-ray diffraction.

Crystals of pure potassium dihydrogen phosphate KH(2)PO(4) (KDP) and Mn-doped KDP (KDP:Mn) were grown from a water solution by the slow evaporation method and their piezoelectric properties were studied by X-ray diffraction methods. The results have shown an increase in the piezoelectric coefficients with the doping.