The aim of this study was to evaluate the influence of the age of bulls at grazing on their diurnal behaviour in Setaria sphacelata meadows. The forage variables were the availability and nutritive value of the diet, and the animal variables were body weight, size and frequency of bites, and diurnal behaviour. Four Brown Swiss x zebu crossed bulls with an initial live weight of 285.8 ± 18.1 kg that grazed in an area of 29 ha (11 paddocks) were selected from a group of 36 bulls. The evaluations were done when the animals reached the ages of 12 (T1), 15 (T2) and 18 (T3) months. A randomized complete block design was used. Forage availability showed differences (p<0.05) between treatments; however, the forage allocation and the nutritional quality of the diet did not compromise their performance. Bite weight was higher in T3 (0.87 ± 0.22 g per bite; p<0.05), but without differences ...

El autor da a conocer las diversas técnicas conductuales-cognitivas que el psicoterapeuta especialista en adicción puede aplicar en cada etapa del proceso de recuperación del paciente.

The authors are indebted to the group of Prof. Dr. A. Conde for sample supplies. This work was partially supported by the CONCYTEC of the Peruvian Government, by CNPq (PCI-program) of the Brazilian Government and by the Latin American Center of Physics. E. Baggio-Saitovitch thanks FAPERJ for the support as Cientista do Nosso Estado.

The possibility of using biomass as a precursor of silicon carbide (SiC) has been studied for many years. In this research, reaction-formed silicon carbide was synthesized from sawdust residues of Peruvian wood. Residues were packed into cylindrical solid pieces through hot pressing and they were subsequently pyrolyzed in an inert atmosphere and infiltrated with metallic silicon in a vacuum atmosphere. SiC pieces were obtained with silicon remaining in their pores, so a chemical attack was performed to clean the samples. Mechanical and thermomechanical properties were evaluated in different environments to know the behavior of SiC through compression tests. The highest values were obtained at room temperature under normal conditions, a maximum stress of 686 MPa was achieved. In all cases, the samples had a fragile behavior as expected. In thermomechanical tests it was observed that resis...

Fe 50 Ni 50 alloy powder was prepared by milling the 1:1 stoichiometric mixture of Fe and Ni high purity elements using high energy vibrational ball-mill. Final powdered material was obtained directly after 30 h of milling process and the Rietveld analysis of the X-ray diffraction pattern of the sample reveals the presence of two Fe–Ni phases: the disordered ?–(Fe 45 Ni 55 ) alloy, with 91% of total fraction of the material (Fe–Ni solid solution plus grain boundary regions) and the chemically-ordered FeNi phase (9%), with L1 0 tetragonal structure. Average grain sizes of these Fe–Ni phases are respectively 60 nm and 20 nm. Results of extended X-ray absorption fine structure of Ni and Fe as well as 57 Fe Mössbauer spectroscopy also suggest the presence of atomically ordered FeNi phase. Mössbauer data have also shown that both Fe–Ni phases are magnetically ordered at room tempe...

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This work presents the results of the analysis done on obsidians samples that belong to three archeological collections at the Museum of Archeology and Anthropology of San Marcos University (MacNeish's collection, • dated toan age 8000- 3500 b. C.) and the I.N.C. Regional Museum at lea (Maymi and Casa Vieja collections, corresponding to the Middle Horizon period 800 a. D.). Additionaly, with the idea ofundertaking future work on the establishment of trade routes and provenience studies in Andean populations, sorne obsidian samples from volcanic sources near to the gathering points are studied. 57Fe Mossbauer spectroscopy (MS), X Ray Fluorescence, Proton Induced X- Ray Emission Spectroscopy (PIXE), Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES) and Inductively Coupled Plasma-Mass Spectroscopy (ICP-MS) were used to analysis. MS study provides the cation ratio Fe2+/Fe3,...

In this research we studied the fruit of «Níspero de la Sierra>) as functional food. The carotenoids have been fractioned in two bands by layer chromatography. The major pigment was identified by it's spectral caractheristics in several solvents: ¡3-caroteno (15.18 mg/kg). The cuantification of minerals and proximal analysis were: potasium (1566 ppm), sodium (745 ppm), calciumn (424 ppm), magnesio (290 ppm), iron (5.40 ppm); and carbohidrates (34 .72%), respectively.

In this research we studied the fruit of «Níspero de la Sierra>) as functional food. The carotenoids have been fractioned in two bands by layer chromatography. The major pigment was identified by it's spectral caractheristics in several solvents: ¡3-caroteno (15.18 mg/kg). The cuantification of minerals and proximal analysis were: potasium (1566 ppm), sodium (745 ppm), calciumn (424 ppm), magnesio (290 ppm), iron (5.40 ppm); and carbohidrates (34 .72%), respectively.

In this work, we study the synthesis process and structural and magnetic characterization of the ?-Al5Fe2 intermetallic alloy obtained by the arc-melting technique. Subsequently, in order to obtain homogeneous crystalline phase, all melted samples were annealed at 847?C during 2 days, and then quenched into water. The structural and micro-structural characterization of the samples were performed by X-ray diffraction and,57Fe transmission Mössbauer spectroscopy, while the morphological study was performed using scanning electron microscopy. Moreover, magnetic characterization was carried out using vibrating sample magnetometer. X-ray fluorescence was employed for elemental characterization. The results indicate that it is possible to employ the arc-melting technique to synthesize the ?-Al5Fe2 intermetallic phase with high structural quality: orthorhombic crystalline structure and Cmcm sp...

Geopolymers are a class of inorganic synthetic materials that in recent years have received extensive interest of the scientific community, mainly due to the variety of applications in which they can be used. The synthesis of these materials is based on a chemical process called geopolymerization, which consists of the alkaline activation of amorphous alumina and silica oxides present in many natural raw materials and industrial solid waste. Therefore, the present work proposes the use of inorganic mining residues (mine tailings) from gold mining in the southern region of Peru, for the manufacture of geopolymeric concrete. The first part of the research focused on the physical, structural and microstructural characterization of the raw material (fine sand and mining tailings), then the volumetric matrix of mixtures for five types of geopolymer concrete was determined. Cylindrical samples...

Geopolymeric materials have recently been considered a revolutionary class of materials, due to the diversity of applications where they can be used, this derived from their good mechanical resistance, thermochemical stability and good fire resistance. From 1970 to the present, a notable increase has been observed in the number of scientific publications dealing with the synthesis and applications of geopolymeric materials with industrial application. Several publications have reported geopolymers as alternative materials to Portland cement, which will allow having a green construction industry in the coming years. The elaboration of geopolymeric materials is relatively simple, beginning with the identification of a source rich in amorphous aluminosilicates and a hardening compound (mainly alkaline in nature) which are properly mixed until a homogeneous and workable paste is obtained, th...

Biomorphic SiC/Si compounds were fabricated from copaiba wood (Copaifera officinalis, natural wood native to Peru), by reactive infiltration of molten silicon in a porous carbon preform obtained by a controlled pyrolysis process of wood. Structural and microstructural characterization tests by X-ray diffraction and scanning electron microscopy, respectively, revealed, on the one hand, the presence of crystalline phases of SiC, Si and C, and on the other, the typical morphology of this type of material, which it consists of a continuous SiC scaffold with elongated channels in the direction of tree growth and the presence of residual Si and C located mainly in the porosities of the material. The mechanical behavior in uniaxial compression was also studied at a constant compression rate of 0.05 mm/min and as a function of temperature (from ambient to 1400 ºC) and test atmosphere (ambient a...

The Tropical Peruvian Andes host  a great ecosystem diversity such as the montane cloud forest at the southern east slopes. The subaerial moist habitats  along the Alccamayo creek  belong to Aguas Calientes,  Cusco . They were evaluated  in  winter (august 2017) between 2184  and 3000 m of elevation with the  mean temperature between 16 and 18°C. In the southern  highland Andean, the  cryosphere of  the  Allincapac glaciers, Carabaya  Cordillera, Puno,  was evaluated  in summer season (february 2018) between 4500 and 4700 m elevation. The thermogradients were between 0 and 10°C and pH between 6.0 and 6.5. Collections of subaerophytic assemblages with litophilic, and  chasmolithic microalgae and cyanobacterial  were carried out  by scraped the biofilms or crusts from the cliffs of  calcareous  rock  surfaces  or ice layers. Highland colonization (Allincapac  glaci...