Federal University of Roraima

About: Federal University of Roraima is a based out in . It is known for research contribution in the topics: Population & Thermogravimetry. The organization has 981 authors who have published 1218 publications receiving 7849 citations. The organization is also known as: Federal University of Roraima.

Carbon Nanotube with Square Cross-section: An Ab Initio Investigation

Abstract: Recently, Lagos et al. (Nature Nanotechnology 4, 149 (2009)) reported the discovery of the smallest possible silver square cross-section nanotube. A natural question is whether similar carbon nanotubes can exist. In this work we report ab initio results for the structural, stability and electronic properties for such hypothetical structures. Our results show that stable (or at least metastable) structures are possible with metallic properties. They also show that these structures can be obtained by a direct interconversion from SWNT(2,2). Large finite cubane-like oligomers, topologically related to these new tubes were also investigated.

A construção do espaço étnico roraimense, ou: os Taurepáng existem mesmo?

Abstract: Taking the publication - in 1989 and 1990 - of of two "historic-anthropological" booklets as an typically "orientalist" trial of the Diocese of Roraima to impose a "consensus" on Roraima society with relation to the "ethnic reality" of that state of Brazil, we reconstruct the history of the formation of that "consensus", starting in the 18th century, up to the decisive ethnography of Theodor Koch-Grunberg.

Qualidade microbiológica de polpas de frutas congeladas

Abstract: The production of fruit pulps is an economical alternative in the State of Roraima, Brazil where these products meet with general acceptance. The market is also supplied with pulps coming from other places. The local producers prepare them craftsmanly without any adequate processing quality control. Aiming at evaluating the microbiological quality of frozen fruit pulps marketed in Boa Vista, RR, 100 samples were collected, from five commercial brands, and of four fruit flavours. The sample from a brand was a pasteurized product and derived from another State, and the four other were in natura fruit pulps samples which were locally produced. It was observed a significant growing of moulds, yeasts and heterotrophic bacterias on the analyzed samples, but it wasn’t detected the presence of Salmonella sp. and neither coliforms significant development. Of 100 analyzed samples, 78% were not in compliance with the established microbiological standards for mould and yeast. In natura pulps (locally produced) showed higher index of inadequate results than pasteurized pulps. The high percentual of unsatisfactory samples indicate that it is necessary to adequate the productive procedures in accordance to the legal requirements.

Synthesis, characterization and thermogravimetric study of Cu(II) adducts with 3- and 4-amino-1,2,4-triazole, 2-mercaptothiazoline and 2-mercaptopyridine

Abstract: The adducts CuCl 2 ·(3amt), CuCl 2 ·2(3amt)·2H 2 O, CuCl 2 ·3(3amt), CuCl 2 ·(4amt), CuCl 2 ·2(4amt), CuCl 2 ·3(4amt)·2H 2 O, CuCl 2 ·(2mct)·H 2 O, CuCl 2 ·2(2mct)·2.5H 2 O, CuCl 2 ·3(2mct)·2H 2 O, CuCl 2 ·(2mcp) and CuCl 2 ·2(2mcp)·H 2 O, where 3-amino-1,2,4-triazole = 3amt, 4-amino-l,2,4-triazole = 4amt, 2-mercaptothiazoline = 2mct and 2-mercaptopyridine = 2mcp, were synthesized by a solid state route and characterized by CHN elemental analysis and infrared spectroscopy. A thermogravimetric study was also performed. It was verified that 4amp is a molecule with a higher ability to act as a bridging ligand in comparison with 3amp. It was also found that, for all compounds, the mono adducts were the most thermally stable ones. Such a fact is in agreement with a higher ionic and covalent character of the metal-ligand bond in surch compounds.