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.

Decrease of interlamellar spacing of silica samples induced by external pressure

Abstract: Lamellar silica and cadmium or mercury derivative-doped samples were synthesized by neutral amine route through the sol‐gel process. These samples showed a decrease of the interlamellar d-space promoted only by an increase of the externally applied pressure on the samples. For a constant external pressure the observed decrease has a linear behavior as a function of time. The undoped lamellar silica, when pressed under 760 mPa for 45 min, exhibited a decrease of the interlamellar distance of 16%. The obtained results suggested that under an increased external pressure, cadmium is forced to change its coordination environment, to adjust to a most stable structure. ” 2000 Elsevier Science B.V. All rights reserved.

Chemical Composition and Evaluation Preliminary of Antileishmanial Activity in vitro of Essential Oil from Leaves of Eugenia pitanga, A Native Species of Southern of Brazil

Abstract: Eugenia pitanga (O.Berg) Nied., Myrtaceae, popularly known as pitanga-do-campo, is a species native from Pampa biome, in southern of Brazil and is popularly used as antidiarrheal, anti-rheumatic, stimulant and febrifuge. The aim of this work was to determine the chemical composition of essential oil from fresh leaves of Eugenia pitanga (O.Berg) Nied. Preliminaries data about antileishmanial activity in vitro of essential oil against promastigotes forms of Leishmania amazonensis are presented. The method to determine the chemical composition of the essential oil from fresh leaves of E. pitanga (EoEp) was gas chromatography-mass spectrometry. EoEp was assayed in vitro for antileishmanial activity against promastigotes of Leishmania amazonensis. The EoEp comprised 57 components and was rich in oxygenated sesquiterpenes (72.97 %) with spathulenol (15.34 %), globulol (10.93 %) and (2E,6E) methyl farnesoate (7.40 %) as the major constituents. EoEp was effective against L. amazonensis promastigotes with ...

Surgical time and complications of total transvaginal (total-NOTES), single-port laparoscopic-assisted and conventional ovariohysterectomy in bitches

Abstract: The recently developed minimally invasive techniques of ovariohysterectomy (OVH) have been studied in dogs in order to optimize their benefits and decrease risks to the patients. The purpose of this study was to compare surgical time, complications and technical difficulties of transvaginal total-NOTES, single-port laparoscopic-assisted and conventional OVH in bitches. Twelve bitches were submitted to total-NOTES (NOTES group), while 13 underwent single-port laparoscopic-assisted (SPLA group) and 15 were submitted to conventional OVH (OPEN group). Intra-operative period was divided into 7 stages: (1) access to abdominal cavity; (2) pneumoperitoneum; approach to the right (3) and left (4) ovarian pedicle and uterine body (5); (6) abdominal or vaginal synthesis, performed in 6 out of 12 patients of NOTES; (7) inoperative time. Overall and stages operative times, intra and postoperative complications and technical difficulties were compared among groups. Mean overall surgical time in NOTES (25.7±6.8 minutes) and SPLA (23.1±4.0 minutes) groups were shorter than in the OPEN group (34.0±6.4 minutes) (P<0.05). The intraoperative stage that required the longest time was the approach to the uterine body in the NOTES group and abdominal and cutaneous sutures in the OPEN group. There was no difference regarding the rates of complications. Major complications included postoperative bleeding requiring reoperation in a bitch in the OPEN group, while minor complications included mild vaginal discharge in four patients in the NOTES group and seroma in three bitches in the SPLA group. In conclusion, total-NOTES and SPLA OVH were less time-consuming then conventional OVH in bitches. All techniques presented complications, which were properly managed.

Doses e épocas de aplicação de nitrogênio em arroz de várzea

Abstract: The most outstanding crop, concerning agribusiness in the Roraima State, is lowland rice. Therefore, the recommendation of new cultivars, as well as the study of correct handling for nitrogen fertilizing, are important to maximize grain yield and reduce production costs and environmental impacts. Thus, the objective of this study was to identify the nitrogen doses and application times most adjusted to the rice cultivar BRS Jacana, in Roraima lowlands. The experiment took place at the Santa Cecilia Farm, a lowland area of the Rio Branco river, in Canta, Roraima State, Brazil, from December (2007) to March (2008), on a tb distrophic haplic gleissol. The experiments were conducted under a split-plot scheme, with plots displayed under a randomized blocks design with four replicates. Treatments consisted of four N doses (50 kg ha -1 , 100 kg ha -1 , 150 kg ha -1 , and 200 kg ha -1 ), combined with four application times: E1 - half dose at sowing and half 45 days after emergence (dae); E2 - half dose 15 days after emergence (dae) and half 45 days after emergence (dae); E3 - one application 15 days after emergence (dae); and E4 - one application 45 days after emergence (dae), totalizing 16 treatments and 64 experimental units. Concerning the BRS Jacana lowland rice cultivar, the best combination was the application of 118 kg ha -1 of nitrogen, half at sowing and half 45 days after emergence. KEY-WORDS: Oryza sativa L.; lowland rice; maximum economic yield.

Thielaviopsis ethacetica the etiological agent of sugarcane pineapple sett rot disease in Brazil

Abstract: Sugarcane pineapple rot is an important sugarcane stem disease that also affects germination and sprouting. In Brazil, the disease is caused by Thielaviopsis paradoxa sensu lato which has been split into at least five distinctive phylogenetic and biological species in the reinstated genus Thielaviopsis. In this study, three purported strains of T. paradoxa s. lat. isolated from sugarcane stems were characterized and compared with a strain from pineapple fruit, using morphology, DNA sequence analyses and sexual compatibility tests. Inoculations were also performed on asymptomatic stems of plants to assess the pathogenicity of the four fungal strains on sugarcane. Based on results of the phylogenetic analyses of combined ITS and TEF-1a gene sequences, the strains were identified as T. ethacetica. This was also supported by sexual compatibility tests, as crossings between the pineapple strain and some sugarcane strains resulted in the formation of perithecia exuding ascospore masses at their apices. The inoculation test on sugarcane resulted in stem rot and in reduced germination of buds. Thielaviopsis ethacetica is thus the species causing pineapple sett rot disease in Brazil.