RESUMO
In this paper we studied the reversal magnetization of La1-x Sr x Fe0.5Cr0.5O3-δ (x = 0, 0.1 and 0.2) samples produced by combustion synthesis. The structural analysis was carried out by x-ray diffraction with Rietveld analysis. These analyses revealed that all samples have an orthorhombic structure with space group Pbnm (62) and that the Sr-doping induces a decrease of the lattice parameter. The x-ray photoelectron spectroscopy analysis indicates that the Sr-doping favor the change of the valence states of the Fe3+ to Fe4+. The magnetization as a function of the temperature reveals an unusual magnetic behavior with a reversal of magnetization. The increase of the Sr content induces a decrease of the temperature where occurs an inversion of the magnetization and do the value of the magnetization at 5 K more negative. This effect is attributed to the increase of the concentration of Fe4+ with increasing of the Sr content. The Fe and Cr with a valence of 4+ act as paramagnetic impurities in the antiferromagnetic lattice and are responsible for the changes in the magnetic behavior.
RESUMO
We report the first observation of the field distribution and flux-line lattice (FLL) depinning in the vortex-state (VS) of a type-II superconductor probed by conduction electron spin resonance (CESR). CESR was performed in MgB (2) (T(c) approximately 39 K) at 4.1 GHz (1455 Oe) and 9.5 GHz (3390 Oe). The field distribution, n(H), and a standard deviation of sigma approximately 14 Oe (at 28 K/4.1 GHz and at 7 K/9.5 GHz) were inferred, respectively, from the distortion and broadening of the CESR in the VS. For both frequencies, the FLL depinning temperature was determined.
RESUMO
The exchange interactions in polycrystalline samples of Ca1-xLaxMnO3 (0.00< or =x< or =0.05) are studied by means of Raman scattering and electron paramagnetic resonance. Dramatic reductions in the spin-phonon interactions and magnetic correlations are observed for La doping levels as small as approximately 2%-3%. These results show that the charge carriers play an important role in the overall exchange coupling in the electron-doped manganites, even at very low doping levels.
RESUMO
The purpose of this study is to report the results of the authors' investigation to apply the western blot technique (WB UP-LCS) in the diagnosis of human immunodeficiency virus type 1 (HIV-1) infection. To do this, the authors separated the proteins of the HIV-1 virus by electrophoresis, based on their molecular weight, in poliacilamide gel with SDS (SDS-PAGE) during 3 hours at 200 volts. Then they electrotransferred these proteins to nitrocellulose paper during four hours at 200 milliamperes, with the aid of external cooling. The nitrocellulose strips were evaluated considering the incubation time (1 and 16 hours), two conjugates (human anti IgG with Peroxidase and human anti IgG Biotin plus Streptatividine with Peroxidase) and two dilutions of the patients' sera (1/50 and 1/100). Based on their results the Authors conclude that, in the first place, the optimal conditions for the test include a dilution of 1/100 of the patients serum, incubation of the serum for 16 hours and the use of the conjugate of anti human IgG with Biotin and Streptavidine with Peroxidase; secondary, that the immunologic reactivity against proteins p24 and gp 160/120 is the most important diagnostic criterion for the confirmation of infection with HIV-1 and that they obtained a diagnostic correlation of 100% at a cost which was 5 to 7 times less than that of the commercial system
Assuntos
Humanos , HIV-1 , Anticorpos Anti-HIV/sangue , Infecções por HIV/diagnóstico , Western Blotting/métodos , Eletroforese em Gel de Poliacrilamida/métodos , Estudo de Avaliação , Fatores de Tempo , Western Blotting/estatística & dados numéricosRESUMO
The purpose of this study is to report the results of the authors' investigation to apply the western blot technique (WB UP-LCS) in the diagnosis of human immunodeficiency virus type 1 (HIV-1) infection. To do this, the authors separated the proteins of the HIV-1 virus by electrophoresis, based on their molecular weight, in poliacilamide gel with SDS (SDS-PAGE) during 3 hours at 200 volts. Then they electrotransferred these proteins to nitrocellulose paper during four hours at 200 milliamperes, with the aid of external cooling. The nitrocellulose strips were evaluated considering the incubation time (1 and 16 hours), two conjugates (human anti IgG with Peroxidase and human anti IgG Biotin plus Streptatividine with Peroxidase) and two dilutions of the patients' sera (1/50 and 1/100). Based on their results the Authors conclude that, in the first place, the optimal conditions for the test include a dilution of 1/100 of the patients serum, incubation of the serum for 16 hours and the use of the conjugate of anti human IgG with Biotin and Streptavidine with Peroxidase; secondary, that the immunologic reactivity against proteins p24 and gp 160/120 is the most important diagnostic criterion for the confirmation of infection with HIV-1 and that they obtained a diagnostic correlation of 100% at a cost which was 5 to 7 times less than that of the commercial system.
Assuntos
Western Blotting/métodos , Anticorpos Anti-HIV/sangue , Infecções por HIV/diagnóstico , HIV-1 , Western Blotting/estatística & dados numéricos , Eletroforese em Gel de Poliacrilamida/métodos , Estudos de Avaliação como Assunto , Humanos , Fatores de TempoRESUMO
The authors examined 70 original samples obtained from 70 women seen at the Nuevo Veranillo Community Health Center because of suspected Mycoplasma infection. 23 (33%) of the cultures were positive for Mycoplasma. The microscopic and chemical characteristics identified 3 (13%) as Ureaplasma urealyticum, 9 (39%) were Mycoplasma hominis and 11 (48%) were positive for both organisms. The rate of positive cultures for Mycoplasma was high, which could be an important finding since these organisms are associated to a variety of pathologic conditions in adults of both sexes, in pregnant women and in their offspring.
Assuntos
Colo do Útero/microbiologia , Mycoplasma/isolamento & purificação , Ureaplasma urealyticum/isolamento & purificação , Adolescente , Adulto , Feminino , Humanos , Pessoa de Meia-Idade , Infecções por Mycoplasma/microbiologia , Panamá , Infecções por Ureaplasma/microbiologia , Vaginose Bacteriana/microbiologiaRESUMO
The authors examined 70 original samples obtained from 70 women seen at the Nuevo Veranillo Community Health Center because of suspected Mycoplasma infection. 23 (33%) of the cultures were positive for Mycoplasma. The microscopic and chemical characteristics identified 3 (13%) as Ureaplasma urealyticum, 9 (39%) were Mycoplasma hominis and 11 (48%) were positive for both organisms. The rate of positive cultures for Mycoplasma was high, which could be an important finding since these organisms are associated to a variety of pathologic conditions in adults of both sexes, in pregnant women and in their offspring
Assuntos
Humanos , Feminino , Adolescente , Adulto , Pessoa de Meia-Idade , Colo do Útero/microbiologia , Mycoplasma/isolamento & purificação , Ureaplasma urealyticum/isolamento & purificação , Infecções por Mycoplasma/microbiologia , Infecções por Ureaplasma/microbiologia , Panamá , Vaginose Bacteriana/microbiologiaRESUMO
70 samples of vaginal secretions were collected from women with bacterial vaginosis syndrome, that were attended in Nuevo Veranillo' Health Center. All samples were tested in order to determinate the presence of amine and to Gram'methods stain to observe the morphologic characteristics of the "Clue" cells (epithelial cells with adhered bacteria). Samples were cultured in a selective media of blood agar in Columbia base with colistine and nalidixic acid, and incubated in an environment of CO2 at 37 degrees C. Tests of oxidase, catalase, glucid fermentation, hippurate hydrolysis and starch hydrolysis were made on the grown colonies. 27 out of 70 samples resulted in positive cultures for Gardnerella vaginalis, 11 to pregnant women and 16 to nonpregnant women; among these, 14 women used some kind of contraceptive methods as DIU or pill.
Assuntos
Gardnerella vaginalis/isolamento & purificação , Vaginose Bacteriana/microbiologia , Adolescente , Adulto , Feminino , HumanosRESUMO
Mycoplasma pneumoniae was isolated for first time in Panama and identified from a nine years old girl with pneumonia. SP4 medium was used to isolate the bacteria. Confirmatory serological results were obtained by indirect immunofluorescence and were also suggested by the presence of cryoagglutinins in the sera of this patient. DNA hybridization tests (Gen--Probe) were carried out.