Evaluation of alternative containers to determining the working width of fertilizer spreaders

Os ensaios de largura de trabalho e uniformidade de distribuição são de difícil execução para o agricultor por exigirem equipamentos, recursos e métodos complexos. Portanto, este trabalho teve como objetivo avaliar coletores alternativos para tornar mais acessível a regulagem e a avaliação de distribuidores de fertilizantes sólidos a lanço. Foram utilizados quatro diferentes conjuntos de coletores: i) coletores construídos segundo a norma ISO 5690/1; ii) coletores de polietileno (bandejas plásticas) com tela de sombreamento para evitar o ricochete de material; iii) coletores formados por caixas de leite longa vida, e iv) coletores formados por vasos de polietileno (número 3,5). Também foram utilizados três diferentes distribuidores para as avaliações. Os coletores alternativos apresentaram maior retenção de partículas que os coletores normatizados. A largura efetiva de trabalho obtida para os coeficientes de variação de 12,5; 15; 17,5 e 20% variou entre os coletores nos diferentes percursos. O coletor que mais se assemelhou à norma foram os vasos de polietileno. Constatou-se que a altura dos coletores foi mais importante para sua eficiência do que a sua área de coleta.

Fission-track dating of South American natural glasses: an overview

Although many glass-bearing horizons can be found in South American volcanic complexes or sedimentary series, only a relatively few tephra and obsidian-bearing volcanic fields have been studied using the fission-track (FT) dating method. Among them, the volcanics located in the Sierra de Guamani (east of Quito, Ecuador) were studied by several authors. Based upon their ages, obsidians group into three clusters: (1) very young obsidians, similar to 0.2Ma old, (2) intermediate-age obsidians, similar to 0.4- similar to 0.8 Ma old, and (3) older obsidians, similar to 1.4- similar to 1.6 Ma old. The FT method is also an efficient alternative technique for identification of the sources of prehistoric obsidian artefacts. Provenance studies carried out in South America have shown that the Sierra de Guamani obsidian occurrences were important sources of raw material for toot making during pre-Columbian times. Glasses originated from these sources were identified in sites distributed over relatively wide areas of Ecuador and Colombia.Only a few systematic studies on obsidians in other sectors were carried out. Nevertheless, very singular glasses have been recognised in South America, such as Macusanite (Peru) and obsidian Quiron (Argentina), which are being proposed as additional reference materials for FT dating. Analyses of tephra beds interstratified with sedimentary deposits revealed the performance of FT dating in tephrochronological studies. A remarkable example is the famous deposit outcropping at Farola Monte Hermoso, near Bahia Blanca (Buenos Aires Province), described for the first time by the middle of the 19th century by Charles Darwin.Considering the large number of volcanic glasses that were recognised in volcanic complexes and in sedimentary series, South America is a very promising region for the application of FT dating. The examples given above show that this technique may yield important results in different disciplinary fields. (c) 2005 Elsevier Ltd. All rights reserved.

Thermochronology of the South American platform in the state of São Paulo, Brazil, through apatite fission tracks

The fission-track method (FTM) in apatite was applied to 45 samples collected in the Serra da Mantiqueira (Mantiqueira mountain range), the Serra do Mar (Mar mountain range), regions next to these mountain ranges and the coastal region between Ubatuba and Santos in the State of São Paulo, Brazil, to study the thermochronology of the South American Platform in southeast Brazil and its influence on Santos and Campos basins. The data presented in this work complement the previously presented data on the same region (Tello Saenz et al., 2003. J. S. Am. Earth Sci. 15, 765-774) with 31 new samples analyzed. The weighted mean of the corrected ages from high Mantiqueira (around 1000 m), (121 +/- 6) Ma, coincides with the South Atlantic opening. The fact that its thermal history starts at a relatively low temperature (similar to 80 degrees C) suggests that the age of similar to 120 Ma would be the formation age of Serra da Mantiqueira due to a rapid pulse, in which tracks had no time to be retained at the closure temperature, that is similar to 120 degrees C. The Serra do Mar presents a more complicated thermal history, with several reactivations indicated by the changes in the slope of its cooling curve. The thermal histories obtained in the regions next to these mountain ranges are compatible with the results mentioned above. The Santos Basin has unconformities that agree with changes in the slope thermal histories of the studied region. (c) 2005 Elsevier Ltd. All rights reserved.

Fission-track dating of Macusanite glasses with plateau and size correction methods

Two Macusanite pebbles (MB1 and MB2) were dated with the fission-track method. Six irradiations were carried out in different nuclear reactors: Pavia (Italy), IPEN-CNEN (Brazil) and IPEN-Lima (Peru). Measurements of the thorium and uranium induced-fission per target nucleus using natural thorium thin films and natural U-doped glasses calibrated against natural uranium thin films, together with lambda(F) of 8.46 x 10(-17) a(-1) were used to determine the ages. The apparent ages were corrected using the plateau and size correction methods. Track measurements were performed by different analysts, using different counting criteria. In addition, tracks were measured on samples which had been submitted to thermal treatment as well as on samples which had not been heated. Thermal treatments were carried out to erase the fossil tracks before neutron irradiation. No significant differences have been found in individual results, using the two Macusanite pebbles and the different nuclear reactors, age correction techniques, analysts, track-counting criteria, and thermal treatments before neutron irradiation. The great majority of the results (14/17) is compatible with the Ar-Ar ages of 5.12 +/- 0.11 and 5.10 +/- 0.11 Ma, Macusanite MB1 and MB2, respectively. However, the fission-track ages are systematically less (similar to8%) than the Ar-Ar ages of the two Macusanite samples studied. (C) 2003 Published by Elsevier Ltd.

New constraints on ages of glasses proposed as reference materials for fission-track dating

New analyses have been performed in order to enhance the data-set on the independent ages of four glasses that have been proposed as reference materials for fission-track dating. The results are as follows. Moldavite - repeated (40)Ar/(39)Ar age determinations on samples from deposits from Bohemia and Moravia yielded an average of 14.34 +/- 0.08 Ma. This datum agrees with other recent determinations and is significantly younger than the (40)Ar/(39)Ar age of 15.21 +/- 0.15 Ma determined in the early 1980s. Macusanite (Peru) -four K-Ar ages ranging from 5.44 +/- 0.06 to 5.72 +/- 0.12 Ma have been published previously. New (40)Ar/(39)Ar ages gave an average of 5.12 +/- 0.04 Ma. Plateau fission-track ages determined using the IRMM-540 certified glass and U and Th thin films for neutron fluence measurements agree better with these new (40)Ar/(39)Ar ages than the previously published ages. Roccastrada glass (Italy) - a new (40)Ar/(39)Ar age, 2.45 +/- 0.04 Ma, is consistent with previous determinations. The Quiron obsidian (Argentina) is a recently discovered glass that has been proposed as an additional reference material for its high spontaneous track density (around 100 000 cm(-2)). Defects that might produce spurious tracks are virtually absent. An independent (40)Ar/(39)Ar age of 8.77 +/- 0.09 Ma was determined and is recommended for this glass. We believe that these materials, which will be distributed upon request to fission-track groups, will be very useful for testing system calibrations and experimental procedures.

Fission track and U-Pb in situ dating applied to detrital zircon from the Vale do Rio do Peixe Formation, Bauru Group, Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Effects of Etching on Zircon Grains and Its Implications for the Fission Track Method

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Micro-Raman spectroscopy and SEM/EDX applied to improve the zircon fission track method used for dating geological formations

The zircon mineral is widely studied in geochronology. In the case of the fission track method (FTM), the age is determined by the density of fission tracks at the zircon surface, which can be observed with an optical microscope after an appropriate chemical treatment (etching). The etching must be isotropic at the zircon grain surface to be used in the FTM, which leads those zircon grains whose etching is anisotropic to be discarded. The only reason for this discarding is the nonuniform morphology of the surface grain seen by optical microscopy, that is, no further physicochemical analysis is performed. In this work, combining micro-Raman and scanning electron microscopy (SEM) to study the etching anisotropy, it was shown that zircon grains that present at least one area at the surface where the density of fission track is uniform can be used in the FTM. The micro-Raman showed characteristic spectra of the standard zircon sample either from the areas where there are tracks or from where there are not. The only difference found was in the Raman bandwidths, which were broader for the areas with higher density of fission tracks. This suggests simply a decrease in the relative percentage of the crystalline/amorphous phases at these areas. The SEM/energy dispersive spectrometry (EDX) showed that there were no significant differences in the principal chemical composition at the areas with and without fission tracks. Copyright (c) 2008 John Wiley & Sons, Ltd.

Group analysis method for fission track thermochronology

A methodology to obtain ages and thermal histories of sets of apatite samples from localities with geologically compatible characteristics is described. A methodology exploring the fact that samples with similar geological characteristics should present the same thermal history is proposed. This approach can contribute for the obtainment of more conclusive results by analysing fewer samples than it is necessary when the samples are individually analysed. In order to determine the ages, we use the absolute neutron dosimetry through thin films of natural uranium along with lambda(f) = 8.46 x 10(-17) a(-1). As an example of application of the proposed methodology, we analyse samples collected in a Brazilian region, Sao Francisco Craton, which experienced low tectonic activity. (C) 2008 Elsevier Ltd. All rights reserved.

Zircon fission track and U-Th-Pb in situ dating of Rio Parana Formation, Parana Basin, Brazil

Ages of zircon from sedimentary samples of Rio Parana Formation, belonging of Bauru Group, north of Parana Basin, Brazil, has been determined by zircon Fission Track and U-Th-Pb in situ dating methods. The obtained ages are from same zircon grain that provided information on the source areas for the sediments and the morphotectonic events.

Periodontal and Prosthetic Biologic Considerations to Restore Biological Width in Posterior Teeth

\ The biologic width is an essential dental space that always needs to be maintained to ensure periodontal health in any dental prosthetic restorations. An iatrogenic partial fixed prosthesis constructed in lower posterior teeth predisposed the development of subgingival caries, which induced violation of the biologic width in involved teeth, resulting in an uncontrolled inflammatory process and periodontal tissue destruction. This clinical report describes a periodontal surgical technique to recover a violated biologic width in lower posterior teeth, by crown lengthening procedure associated with free gingival graft procedure, to ensure the possibility to place a modified partial fixed prosthesis in treated area. The procedure applied to recover the biologic width was crown lengthening with some modifications, associated with modified partial fixed prosthesis to achieve health in treated area. The modified techniques in both surgical and prosthetic procedures were applied to compensate the contraindications to recover biologic width by osteotomy in lower posterior teeth. The result, after 4 years under periodic control, seems to achieve the projected goal. Treating a dental diseased area is necessary to diagnose, eliminate, or control all etiologic factors involved in the process. When the traditional methods are not effective to recover destructed tissues, an alternative, compensatory, and adaptive procedure may be applied to restore the sequelae of the disease, applying a restorative method that respects the biology of involved tissues.

Biologic width changes around loaded implants inserted in different levels in relation to crestal bone: histometric evaluation in canine mandible

Objectives: The aim of the present study was to evaluate histometric changes around dental implants inserted at different levels in relation to the crestal bone, under different loading conditions.Material and methods: Thirty-six implants were inserted in the edentulous mandible of six mongrel dogs. Each implant was assigned to an experimental group according to the distance from the top of the implant to the crestal bone: Bone Level (at the crestal bone level), Minus 1 (1 mm below the crestal bone) or Minus 2 group (2 mm below the crestal bone). Each hemimandible was submitted to a loading protocol: conventional or immediate restoration. After 90 days, the animals were killed. Specimens were processed, and measurements were performed concerning the length of soft and hard peri-implant tissues. Data were analyzed using ANOVA and Student's t test (alpha=5%).Results: Among conventionally restored sites, the distance from the most coronal position of soft tissue margin (PSTM) and first bone-implant contact (fBIC) was greater for Minus 2 than for Bone Level and Minus 1 sites (P=0.03), but significant differences were not observed among immediately restored sites. Differences among groups were not observed concerning the PSTM, and the distance from the implant-abutment junction to fBIC. Greater amounts of lateral bone loss were observed for conventionally than for immediately restored sites (P=0.006).Conclusions: These findings suggest that the apical positioning of the top of the implant may not jeopardize the position of soft peri-implant tissues, and that immediate restoration can be beneficial to minimize lateral bone loss. Further studies are suggested to evaluate the clinical significance of these results in longer healing periods.

CORRELATING THE CURVE DISTANCE BETWEEN THE DISTAL of THE CANINES TO THE COMBINED WIDTH of THE SIX ANTERIOR TEETH WHEN SELECTING DENTURE TEETH FOR DIFFERENT ETHNIC GROUPS

Statement of problem. To select the width of denture teeth, the distance between the marks indicating the location of the canines is usually measured around the curvature of the wax occlusal rim; however, most manufacturers' mold charts provide the measurements of the artificial 6 anterior teeth as if they were on a straight line.Purpose. The purpose of this study was to investigate whether the curve distance between the distal surfaces of the maxillary canines can be related to the combined width (straight measurement) of the 6 anterior teeth in 4 ethnic groups.Material and methods. Maxillary stone casts were obtained for 160 dentate subjects of 4 ethnic groups (40 whites, 40 blacks, 40 multiracial - descendants of white and black parents, and 40 Asians). The width of each maxillary anterior tooth was measured on the casts with sliding calipers. The combined width of the 6 anterior teeth (CW) corresponded to the sum of the width of each anterior tooth. The curve distance between the distal surfaces of the canines (CD) was measured by using dental tape and sliding calipers. The Pearson correlation coefficient and regression analysis were used to evaluate the relationship between CD and CW in each ethnic group (alpha=.05).Results. The mean CD and CW values (in mm) obtained were: whites (CD=52.12; CW=45.65); blacks (CD=56.10; CW=48.13); multiracial (CD=53.58; CW=46.54); and Asians (CD=53.29; CW=46.60). Significant (P<.001) correlations between CD and CW measurements were observed for all ethnic groups studied (whites, r=0.957; blacks, r=0.803; multiracial, r=0.917; and Asians, r=0.881). The following linear regression equations were obtained: whites [CD=1.1(CW)+0.3]; blacks [CD=0.95(CW)+9.3]; multiracial [CD=1.2(CW)-1.1]; and Asians [CD=1.0(CW)+5].Conclusions. The curve distance between the distal surfaces of the maxillary canines can be accurately related to the combined width of the 6 anterior teeth in the selection of denture teeth for the studied ethnic groups. (J Prosthet Dent 2012;107:400-404)

eta ->gamma gamma decay width via the Primakoff cross section

Incoherent eta photoproduction in nuclei is evaluated at forward angles within 4 to 9 GeV using a multiple scattering Monte Carlo cascade calculation with full eta-nucleus final-state interactions. The Primakoff, nuclear coherent and nuclear incoherent components of the cross sections fit remarkably well previous measurements for Be and Cu from Cornell, suggesting a destructive interference between the Coulomb and nuclear coherent amplitudes for Cu. The inelastic background of the data is consistently attributed to the nuclear incoherent part, which is clearly not isotropic as previously considered in Cornell's analysis. The respective Primakoff cross sections from Be and Cu give Gamma(eta ->gamma gamma)=0.476(62) keV, where the quoted error is only statistical. This result is consistent with the Particle Data Group average of 0.510(26) keV and in sharp contrast (similar to 50%) with the value of 0.324(46) keV obtained at Cornell.