High cycle fatigue of ARMCO iron severely deformed by ECAP

The high-cycle fatigue behavior of ARMCO iron severely deformed by Equal Channel Angular Pressing (ECAP) at room temperature through route Bc until 8 passes, with an average grain size of ~365 nm, was studied and compared with the same material in the annealed state with an average grain size of ~72 µm. The fatigue limit of the 8 passes ECAPed sample increased with respect to the annealed material by more than 250% rising from 274 MPa to 717 MPa. Striations and dimpled relief were observed on the fracture surfaces of the fatigued ultrafine and coarse grain fatigue samples. The microstructure was characterized by Electron Backscattered Diffraction (EBSD) before and after the fatigue tests and it was observed in both samples an increment in the fraction of Low Angle Grain Boundaries (LAGB) at high number of cycles to failure. A texture analysis for the materials after the fatigue failure was done. This study shown a preferential orientation towards the ¿ fiber for both conditions.Peer ReviewedPostprint (author's final draft

Structure-acidity-IR spectra correlations for p-substituted N-phenylsulfonylbenzamides

The wavenumbers of the IR absorption bands of the C=O, S=O and N-H stretching vibrations for a series of p-substituted N-phenylsulfonylbenzamides were measured in trichloromethane. The bond orders, Mulliken charges, charge densities and heats of formation were calculated using the PM3 method. Fifty significant mutual mono parameter (MP) and six dual parameter (DP) correlations were found for the IR spectral, theoretical structural data, substituent constants and previously reported dissociation constants in five polar organic solvents. The transmission of the substituent effects has been discussed and the solvent effect on the slopes of some linear correlations was evaluated using different solvent parameters. The results showed that the factors describing the electronic structure and controlling the dissociation equilibrium and the IR spectra properties of p-substituted N-phenylsulfonylbenzamides must be the same

Las alteraciones de la medula ósea en el perro y el gato

El estudio de la médula ósea, como órgano hématopoyético, es necesario siempre que existan anomalías persistentes o no explicables en el hemograma. En este trabajo se realiza una revisión de las diferentes alteraciones que pueden presentarse en la médula ósea señalando especialmente los detalles morfológicos más importantes para el diagnóstico de los procesos hematológicos a los que acompañan o de los que son origen

Human Cytomegalovirus: detection of congenital and perinatal infection in Argentina

BACKGROUND: Human cytomegalovirus (CMV) is one of the most commonly found agents of congenital infections. Primary maternal infection is associated with risk of symptomatic congenital diseases, and high morbidity is frequently associated with very low birth weight. Neonates with asymptomatic infection develop various sequelae during infancy. This is the first Argentine study performed in neonates with congenital and postnatal HCMV infection. The purpose of this study was to evaluate the performance of the polymerase chain reaction (PCR) technique with different pairs of primers, to detect cytomegalovirus isolated in tissue cultures and directly in urine and dried blood spot (DBS) specimens. Results were compared with IgM detection. METHODS: The study was performed between 1999 and 2001 on routine samples in the Laboratory. A total of 61 urine and 56 serum samples were selected from 61 newborns/infants, 33 patients whose samples were analyzed during the first two to three weeks of life were considered congenital infections; the remaining 28 patients whose samples were taken later than the third week were grouped as perinatal infections, although only in 4 the perinatal transmission of infection was determined unequivocally Cytomegalovirus diagnosis was made by isolating the virus from urine samples in human foreskin fibroblast cells. Three different primer pairs directed to IE, LA and gB genes were used for the HCMV PCR assay in viral isolates. Subsequently, PCR and nested PCR (nPCR) assays with gB primers were performed directly in urine and in 11 samples of dried blood spot (DBS) on Guthrie Card, these results were then compared with serology. RESULTS: The main clinical manifestations of the 33 patients with congenital infection were purpura, jaundice, hepatomegaly and anaemia. Three patients presented low birth weight as single symptom, 10, intracranial calcifications, and 2, kidney failure. In the 28 patients grouped as with perinatal infection, anaemia, hepatosplenomegaly and enzymatic alteration were predominant, and 4 patients were HIV positive. The primers used to amplify the gB region had a PCR positivity rate of 100%, whereas those that amplified IE and LA regions had a PCR positivity rate of 54% and 61% respectively, in CMV isolates. Amplification by PCR of urine samples (with no previous DNA extraction), using primers for the gB region, detected 34/61 positive samples. Out of the 33 samples from patients with congenital infection, 24 (73%) were positive. When nPCR was used in these samples, all were positive, whereas in the remaining 28 patients, two negative cases were found. Cytomegalovirus DNA detection in 11 samples was also carried out in DBS: 7 DBS samples were positive and 4 were negative. CONCLUSIONS: Primers directed to the gB fragment region were the best choice for the detection of CMV DNA in positive isolates. In congenital infections, direct PCR in urine was positive in a high percentage (73%) of samples; however, in patients grouped as with perinatal infection only 36% of the cases were positive. With n-PCR, total sample positivity reached 97%. PCR technique performed in DBS allowed identifying congenital infection in four patients and to be confirmed in 3. These results show the value of nPCR for the detection of all cases of CMV infection. The assay offers the advantage that it may be performed within the normal working day and provides reliable results in a much shorter time frame than that required for either traditional tissue culture or the shell-viral assay

Historia natural del águila <i>Geranoaetus melanoleucus</i>: una revisión

Realizamos una revisión de la literatura y condensamos la informacion de diferentes autores acerca de la historia natural del águila Geranoaetus melanoleucus. Complementamos esta información con nuestras propias observaciones de campo entre localidades a lo largo de Chile. Ellas provienen de la Reserva Nacional Las Chinchillas (300 km al norte de Santiago), de San Carlos de Apoquindo (20 km al este de Santiago) y del Parque Nacional Torres del Paine (350 km al norte de Punta Arenas). Tratamos detalladamente los siguientes tópicos: distribución y taxonomía, color del plumaje e identificación, morfometría y peso, historia de vida y reproducción, uso del hábitat, dieta, ritmos de actividad, tipos de vuelo y conductas de caza, agresión, vocalizaciones, abundancia, mortalidad y otros hábitos.Con este trabajo se actualiza el estado del conocimiento de la biología del águila y se hace accesible la información que se ha documentado en revistas de circulación local y documentos de dificil acceso a la comunidad científica interesada.Natural history of the Grey Eagle-buzzard, Geranoaetus melanolucus: a review. We reviewed and summarized the literature concerning the natural history of the Grey Eagle-buzzard Geranoaetus melanoleucus. We suplement this information with our own field records from three sites along Chile. They are the Chinchilla National Reserve (300 km north of Santiago), San Carlos de Apoquindo (20km east of Santiago), and Torres del Paine National Park (350 km north of Punta Arenas).We covered in detail the following topics: distribution and taxonomy, color and field identification, morphometry and weigth, life history and reproduction, habitat use, diet, activity, flight modes and hunting behavior, aggression, vocalizations, abundance, mortality, and other topics. With this review we update the current knowledge of the biology of the Grey Eagly-buzzard, and render more accessible the information documented in journals and books of local circulation to the interested scientific community

Biopsia de médula ósea en perro : técnica y utilidad diagnóstica

La biopsia de médula ósea demuestra ser una técnica importante en el diagnóstico de algunos procesos caninos. Se describen las indicaciones para la evaluación de una muestra de médula ósea en el perro así como la técnica detallada para la obtención de la misma.The bone marrow biopsy is revealed as a important tool in some canine diseases. Clinical indications for the assesment of canine bone marrow samples are described A detailed technique to get the sample is also shown