Shallow seismicity along a well‐defined section of reactivated Precambrian basement near João Câmara, Brazil (5.5°S, 33.7°W) has continued since August 1986. A magnitude 4.3 event on 21st August with a decaying aftershock sequence and another main shock‐aftershock sequence which started in September were followed by a magnitude 5.1 event on 30th November and 11 events of magnitude 4 or above up to February 1987. A network of up to four vertical component short period seismometers with smoked paper recorders has been deployed since late August 1986. Several thousand events have been recorded above magnitude 0, and activity was still being recorded (about 10 events per day) in May 1987. Simple velocity structure, good transmission and impulsive S arrivals on almost all seismograms combine to facilitate reliable hypocentral locations even for this sparse network, and epicenters define a 25 km linear pattern of seismicity with northeasterly strike, approximately coincident with a Precambrian structural trend. A composite fault plane solution shows dextral shear along this strike with a small normal component. Fault plane solutions and epicenter distribution in Northeastern Brazil suggest an overall picture of E‐W regional compression.

RESUMO -Foram utilizados 28 leitões machos, com peso médio de 28,95 kg, para determinação das perdas endógenas fecais, da absorção verdadeira e da biodisponibilidade do fósforo de diferentes fontes. Utilizou-se o delineamento em blocos casualizados, com sete tratamentos e quatro repetições e um animal por unidade experimental. As rações foram à base de milho e de farelo de soja e o fósforo (P) foi suplementado com os fosfatos bicálcico (FBC), monobicálcico (MBC), superfosfato triplo (ST), superfosfato simples (SS), rocha catalão (ROCHA) e ácido fosfórico (AcF) e da ração-controle sem o P suplementar (CONT). Consumo, excreção por fezes e urina, retenção e absorção do fósforo foram inferiores na ração com menor nível de fósforo. O P inorgânico suplementar não influenciou o consumo, o P endógeno fecal e o P retido. Entretanto, a excreção de P nas fezes foi menor nos animais que consumiram SS e maior naqueles que consumiram ROCHA, enquanto a excreção de P na urina foi maior nos animais que consumiram AcF e menor naqueles que consumiram ROCHA. Concluiu-se que a disponibilidade biológica do P foi de 43,82; 89,44; 82,65; 76,90; 98,73; 90,03; e 63,26 para os tratamentos CONT, FBC, MBC, ST, SS, AcF e ROCHA, respectivamente.Palavras-chave: absorção, metabolismo, nutrição, P 32 , radiofósforo, suínos Bioavailability Determination of Phosphorus from Different Sources, Using the Isotopic Dilution Technique, for Growing SwineABSTRACT -Twenty-eight male pigs averaging 28.95 kg were used to determine endogenous fecal losses, true absorption and phosphorus bioavailability in different phosphorus sources. The experiment was arranged in randomized blocks, with seven treatments and four repplicates and one pig/box. The diets were corn and soybean meal-based and the phosphorus (P) was supplemented through different phosphate sources: dicalcium (FBC), monodicalcium (MBC), triple superphosphate (ST), simple superphosphate (SS), Catalão rock (ROCHA) and phosphoric acid (AcF) and diet control without supplemental P (CONT). Phosphorus intake, excretion through feces and urine, retention and absorption were lower in the diet with smaller phosphorus level. Supplemental inorganic P did not affect intake, endogenous fecal P and retained P. However, the P excretion in the feces was smaller for the animals fed SS and greater for those fed ROCHA. P excretion in the urine was greater for the animals fed AcF and smaller for those fed ROCHA. It can be concluded P bioavailability was of 43.82, 89.44, 82.65, 76.90, 98.73, 90.03, and 63.26 for the treatments CONT, FBC, MBC, ST, SS, AcF and ROCHA, respectively. Key Words: absorption, metabolism, nutrition, P 32 , radiophosphorus, swine R. Bras. Zootec., v.33, n.5, p.1231-1237, 2004 1 Projeto parcialmente financiado pela BUNGE FERTILIZANTES S/A. 2 Zootecnista e doutor em Zootecnia -UFV -36.571-000 -Viçosa -MG (alexandre.teixeira@bunge.com). 3 Professor do Departamento de Zootecnia -UFV -36.571-000 -Viçosa -MG. 4 Professor do Departamento de Zootecnia -UFPI -Teresina -PI. 5 Pesquisadores do Departamen...

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The kinetics of the nitrosation reaction of several substituted sulfonamides and of the denitrosation of the resulting products have been studied. The denitrosation rate is first-order with respect to both the nitroso compound and acid concentration and no effect of added nucleophiles was observed. The denitrosation reaction is general-acid catalysed, with a Brønsted parameter, d , of 0.7, which is independent of the substituents on the aromatic ring. Kinetic solvent isotope effects range from1.20 ± 0.05 to 2.04 ± 0.06 for denitrosation by L 3 O ϩ and from k d AH /k d AD ‫؍‬ 1.5 ± 0.2 to 2.3 ± 0.3 for denitrosation by dichloroacetic acid, which suggest that a rate-determining proton transfer is involved in this reaction. For nitrosation reaction, the absence of catalysis by nucleophilic anions, the observed general-base catalysis ( NO ‫؍‬ 0.3) and the substituent effects suggest a concerted nitrosationdenitrosation process. The Leffler parameters obtained for N ؒ ؒ ؒ H bond formation ( nuc ‫؍‬ 0.7) as well as for N ؒ ؒ ؒ N᎐ ᎐ O bond breaking ( lg ‫؍‬ 0.17) are in favour of an imbalance in the transition state ( imbalance ‫؍‬ 0.53) with the development of a positive charge on the nitrogen adjacent to the nitroso group.

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