Doses and forms of application of phosphorus in vernalized garlic

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Analysis of the different forms of application and types of cutting fluid used in plunge cylindrical grinding using conventional and superabrasive CBN grinding wheels

The work reported here involved an investigation into the grinding process, one of the last finishing processes carried out on a production line. Although several input parameters are involved in this process, attention today focuses strongly on the form and amount of cutting fluid employed, since these substances may be seriously pernicious to human health and to the environment, and involve high purchasing and maintenance costs when utilized and stored incorrectly. The type and amount of cutting fluid used directly affect some of the main output variables of the grinding process which are analyzed here, such as tangential cutting force, specific grinding energy, acoustic emission, diametrical wear, roughness, residual stress and scanning electron microscopy. To analyze the influence of these variables, an optimised fluid application methodology was developed (involving rounded 5, 4 and 3 turn diameter nozzles and high fluid application pressures) to reduce the amount of fluid used in the grinding process and improve its performance in comparison with the conventional fluid application method (of diffuser nozzles and lower fluid application pressure). To this end, two types of cutting fluid (a 5% synthetic emulsion and neat oil) and two abrasive tools (an aluminium oxide and a superabrasive CBN grinding wheel) were used. The results revealed that, in every situation, the optimised application of cutting fluid significantly improved the efficiency of the process, particularly the combined use of neat oil and CBN grinding wheel. (c) 2005 Elsevier Ltd. All rights reserved.

Fluoride release/recharge from restorative materials: effect of fluoride gels and time

This study examined the differences in fluoride release and recharge among four restorative materials following treatment with APF or neutral fluoride gel for one or four minutes. Specimens were immersed in 2 mL of deionized water, while fluoride release was measured at 24-hour intervals for 15 days using an ion-selective electrode and analyzer. The materials were then treated with the fluoride gels. The fluoride release was measured for 15 days. ANOVA (p<0.05) showed higher fluoride release for Ketac-Fil before fluoride application and for Vitremer and Fuji 11 LC after application of APF gel. APF gel yielded higher fluoride release when compared to neutral gel, regardless of the material. Fluoride recharge and release was greater after the four-minute APF gel application, with no difference between the times of application for the neutral gel (p>0.05), except for Ketac-Fil. The pattern of release before and after application of the gels was similar and was higher at day 16 compared to day one for the APF gel for resin materials, with higher release at day 15 compared to the initial for Fuji 11 LC and Vitremer. Et was concluded that RM-GICs were the most effective materials with regards to fluoride release after application of APF gel for four minutes.

Effect of application time of APF and NaF gels on microhardness and fluoride uptake of in vitro enamel caries

Purpose : To evaluate the effect of time of fluoride application gel, acidulated or neutral, on in vitro enamel resistance to demineralization and fluoride uptake. Materials and Methods: One hundred and ninety-two human enamel blocks were used in this study and 144 were treated with fluoride gel, acidulated or neutral, for I or 4 minutes. Ninety-six blocks treated with fluoride and 24 control blocks were submitted to a high cariogenic challenge. After the pH-cycling, enamel demineralization was assessed by surface and cross-sectional microhardness. Fluoride in the enamel blocks was also determined after removing an enamel layer by etching acid. Results: Acidulated fluoride gel formed more fluoride in enamel than neutral gel (P < 0.05), and it was also more efficient in reducing the demineralization of the enamel blocks submitted to a cariogenic challenge than the neutral one (P < 0.05). It was found that the time of application was significant in terms of fluoride uptake, but it did not render the enamel more resistant to dernineralization.

Flexural strength and hardness of reline and denture base acrylic resins after different exposure times of microwave disinfection

Objectives: To evaluate the effect of microwave disinfection on the flexural strength and Vickers hardness of 4 autopolymerized resins (Kooliner [K], Tokuso Rebase Fast [T], Ufi Gel Hard [U], and New Truliner [N]) and 1 denture base resin (Lucitone 550 [L]). Method and Materials: For each material, 48 specimens (64 x 10 x 3.3 mm) were made and divided into 6 equal groups (n = 8). In the control group, specimens were untreated. Before testing, specimens were immersed in 200 mL of distilled water and submitted to disinfection for 1 of the following irradiation times: 1, 2, 3, 4, or 5 minutes. The irradiation procedure was performed twice. The flexural strength was determined using a testing machine MTS-810 and measurements of Vickers hardness were made on Micromet 2100. The values were submitted to ANOVA and Tukey's test (P = .05). Results: The K material showed a significant increase (P = .0010) in flexural strength following 5 minutes of disinfection compared to control specimens. The flexural strength mean values of materials T, U, and N were not significantly affected (P > .05) by disinfection. Compared to the control group, the K material showed a significant increase in hardness (P < .001) following disinfection for 3, 4, and 5 minutes. For material U, disinfection for 4 and 5 minutes produced specimens with significantly increased hardness values (P < .001) compared to the control group. For material N, disinfection for 5 minutes resulted in significantly higher hardness values (P < .001) than the control group. Conclusion: Regardless of the irradiation time, the flexural strength and hardness of the materials evaluated were not detrimentally affected by microwave disinfection. (Quintessence Int 2008;39:833-840)

Influence of Application Methods of Self-etching Adhesive Systems on Adhesive Bond Strength to Dentin

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

Influence of Methods of Application of Self-etching Adhesive Systems on Adhesive Bond Strength to Enamel

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

Influence of concentration, time and method of application of citric acid and sodium citrate in root conditioning.

The aim of this study was to establish the parameters of concentration, time and mode of application of citric acid and sodium citrate in relation to root conditioning. A total of 495 samples were obtained and equally distributed among 11 groups (5 for testing different concentrations of citric acid, 5 for testing different concentrations of sodium citrate and 1 control group). After laboratorial processing, the samples were analyzed under scanning electron microscopy. A previously calibrated and blind examiner evaluated micrographs of the samples. Non-parametric statistical analysis was performed to analyze the data obtained. Brushing 25% citric acid for 3 min, promoted greater exposure of collagen fibers in comparison with the brushing of 1% citric acid for 1 minute and its topical application at 1% for 3 min. Sodium citrate exposed collagen fibers in a few number of samples. Despite the lack of statistical significance, better results for collagen exposure were obtained with brushing application of 25% citric acid for 3 min than with other application parameter. Sodium citrate produced a few number of samples with collagen exposure, so it is not indicated for root conditioning.

Strategic feed formulation for relation of electrolytes to promote performance and prevent heat stress in broilers

An experiment was conducted to evaluate the impact in relation of dietary electrolytes, based on changes in the balance Na+K-Cl (DEB) and the ratio (K+Cl)/Na (DER) on the performance and survival of broilers subjected to acute heat stress. A total of 1575 male broiler chicks from 1 to 46 d of age were allocated in a 5x3 factorial arrangement in a completely randomized design, totaling of 15 treatments with 3 replicates of 35 birds each. The treatments consisted of 5 diets with electrolyte balances, arising from combinations DEB/DER (150/3, 250/2, 250/3, 250/4 and 350/3), associated with different times of application or not of the acute heat stress on birds at 25 and 36 d old. All diets were cornsoybean meal based and formulated to meet or exceed NRC requirements. Chicks had ad libitum access to feed and water in floor pens with wood shavings as litter. It was possible to verify that a DEB of 250 mEq/kg and a DER very close to the 3:1 providing a more nutritionally adequate diet. There was, however, the impossibility of obtaining a more suitable electrolyte ratio for a very low DEB (150 mEq/kg) or very high (350 mEq/kg) and also, to a very narrow DER (2:1) or very wide (4:1), due to an unfavorable performance and survival rate of birds in these conditions electrolytes adjustments of K, Na and Cl. There was clear indication, with significant difference (P < 0.05), that the DER has the potential to improve the performance of broilers, since simultaneous adjustment made in DEB, even in conditions of acute stress. The results of performance and survival rate of this study also indicate clearly that DER could not replace the DEB, and vice versa, in practical diets for broilers. Therefore, it can be affirmed that the strategic formulation of the correct electrolyte balance for DEB and DER enhances the performance and is able to prevent the effect of heat stress in broiler chickens, leading to better performance and survival.

Nitrogênio em cobertura e qualidade fisiológica e sanitária de sementes de painço (Panicum miliaceum L.)

O nitrogênio pode influenciar a qualidade das sementes de várias culturas e os seus efeitos variam com as condições ambientais e o estádio de desenvolvimento da planta em que a aplicação é realizada. Porém, pouco se sabe sobre a influência da adubação nitrogenada na qualidade de sementes da cultura do painço (Panicum miliaceum L.). O objetivo neste trabalho foi avaliar o efeito de doses e épocas de aplicação de nitrogênio em cobertura na qualidade fisiológica e sanitária de sementes de painço, cv. AL Tibagi, produzidas em condições de campo. As sementes foram produzidas no período de dezembro de 2005 a fevereiro de 2006 e as avaliações laboratoriais realizadas de março a agosto de 2006. O delineamento experimental foi de blocos ao acaso, em esquema fatorial 4 x 2, constituído pela combinação de quatro doses (0, 30, 60 e 120 kg ha-1 de N) e duas épocas de aplicação (14 e 28 dias após a emergência - DAE) do fertilizante nitrogenado (uréia) em cobertura, com quatro repetições. A aplicação de N aumentou o vigor das sementes, expresso pelos testes de envelhecimento acelerado e emergência em campo. A aplicação de nitrogênio aos 28 DAE da cultura do painço proporciona maiores IVE e porcentagem de emergência em campo. A sanidade de sementes de painço não é influenciada pelas doses e épocas de aplicação da adubação nitrogenada.

Efeito da época de adubacão nitrogenada em cobertura na producão e qualidade fisiológica de sementes de ervilha (Pisum sativum L)

An important factor in crop production is the nutrient liberation matching the growth rates, so these combined effects together with plant development can reach the best results. In this work, the times of nitrogen application (topdressing) were tested in the rate of 120 kg ha(-1) of N, applied at 20 (T20), 25 (T25), 30 (T30), 35 (T35) and 40 (T40) days after emergency in eight cultivars of pea (Pisum sativum L) (Maria, Kodama, Mikado, Flavia, Luiza, Amelia, Dileta and Marina). Here, the aim was to evaluate the effect of these treatments on yield and seed quality in Cerrado Region. After harvest, the seeds were submitted to the quality tests (germination tests, electric conductivity and emergency under field conditions). The results showed that the peas crops are not influenced by the N timing application. Amongst the eight cultivars studied, the best productivity were for Mariana, Mikado, Amelia, Maria and Flavia and the lowest yield was for Kodama cultivar. The cultivar Mikado showed the best results for the quality tests.

Doses, fontes e épocas de aplicação de nitrogênio em cultivares de arroz

As exigências das culturas pelo nitrogênio são diferenciadas, tanto no que se refere às quantidades, quanto à época de aplicação, sendo que este nutriente pode ser perdido por lixiviação, volatilização e erosão. Conduziu-se este trabalho, com o objetivo de avaliar a resposta das cultivares de arroz BRSMG Curinga e IAC 202 à aplicação de doses, fontes e épocas de aplicação de nitrogênio. Os tratamentos constituíram-se de cinco doses de nitrogênio (0, 50, 100, 150 e 200 kg de N ha-1), sob a forma de três fontes nitrogenadas (sulfonitrato de amônio com inibidor de nitrificação, sulfato de amônio e uréia), em duas épocas de aplicação (semeadura ou perfilhamento), cultivado com irrigação suplementar. O delineamento experimental utilizado foi o de blocos ao acaso em esquema fatorial 5x3x2x2, com quatro repetições. A cultivar de arroz BRSMG Curinga apresentou a maior produtividade. As doses de N aumentaram o teor de N foliar, a altura de plantas, o número de panículas m-2, o número e a massa de espiguetas granadas panícula-1 e a produtividade de grãos, mas não influenciou a massa de 100 grãos. As fontes nitrogenadas e as épocas de aplicação tiveram efeito semelhante para todas as avaliações. A maior produtividade foi alcançada com a dose de 122 kg de N ha-1, independente da fonte utilizada.

Aplicação foliar e em cobertura de nitrogênio na cultura do trigo no cerrado

The nitrogen in wheat is essential for obtaining high yields, not only the dose but also the time and the way of application are critical, reducing potential leaching and the cost of production. The objective is evaluating leaf and sidedressing nitrogen application on wheat crop in years of 2006 and 2007. A randomized blocks design in a factorial scheme 5x3x2 was used. The treatments consisted of five doses of nitrogen in the solution (0; 2.5; 5.0; 7.5 and 10%), three application times (at tillering: 30 days after plant emergency (DAE), at full flowering (50 DAE) + in the beginning of grain formation (70 DAE) and at tillering + in the beginning of grain formation), with and without sidedressing nitrogen applied at 40 DAE, using urea as source. They were evaluated: chlorophyll and nitrogen content in leaf, number of spikelets per ear, number of grains per ear, mass of grains per ear, number of grains per spikelet, mass hectolitric, mass of 100 grains and productivity of grains. The application of nitrogen topdressing in both years, influenced the yield characteristics of wheat. The times of leaf nitrogen only affected the leaf N content. The leaf nitrogen concentrations increased linearly the number of grains per spikelets, grains per spike, chlorophyll content, grain weight per ear and grain yield, and reduced mean weight per hectoliter, only in 2007.