Thermal behaviour of succinic acid, sodium succinate and its compounds with some bivalent transition metal ions

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

Synthesis, Characterization and Thermal Behaviour of Solid 2-Methoxycinnamylidenepyruvate of Light Trivalent Lanthanides

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

Synthesis, characterization and thermal behaviour of heavy lanthanide and yttrium pyruvates in the solid state

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

Thermal behaviour of mandelic acid, sodium mandelate and its compounds with some bivalent transition metal ions

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

Soil-lime reactions: the behaviour of a Brazilian red soil.

A red tropical soil was selected, with the main purpose of investigating how it reacted with calcitic and dolomitic limes, and which products are formed. Under normal (23-28oC) or slightly accelerated (40o and 60oC) conditions there is a rapid and substantial interaction between lime (calcitic or dolomitic) and the soil. The reactions take place in two steps, one before 7 g lime/100 g soil, and the other after 8 g lime/100 g of soil, either for calcitic or dolomitic lime. A morphologically discrete reaction product (tri-calcium aluminate hexahydrate) was found in the study, and in spite of the difference in morphology the product is shown to be the same by XRD for all compositions and T.-J.M.H.

Increased B chromosome frequency and absence of drive in the fish Prochilodus lineatus

The neotropical freshwater fish species Prochilodus lineatus (Pisces, Prochilodontidae) shows 2n = 54 chromosomes plus supernumerary microchromosomes ranging in number from zero to seven among different animals. The transmission rates of B chromosomes were studied by the analysis of the parental and F1 generations in 10 controlled crosses performed with specimens from a natural population. The mean transmission rate observed for B chromosomes (k(B) = 0.511) was consistent with that expected from a regular meiotic behaviour orbs in both sexes and with the theoretical value under a Mendelian mode of transmission (0.5). Possible explanations for the dramatic increase in B frequency observed in this population during the last 10 years are discussed, bearing in mind the current absence of drive.

Escalated aggressive behaviour and facultative parental care in the nest building gladiator frog, Hyla faber

Agonistic encounters and facultative parental care in Hyla faber were observed in two localities in southeastern Brazil. Maximum male density was 0.9 and 3.3 males/m2 in Campinas and Ribeirão Branco, respectively. Aggression was escalated and the highly variable aggressive calls were specific to each phase of the encounter. The last, more aggressive phases rarely occurred in Campinas; in Ribeirão Branco they occurred frequently. Male parental care (egg attendance) was common in Ribeirão Branco while it was never observed in Campinas. Egg attendance lasted one to two nights and was observed only during high male density. The main benefit of egg attendance seemed to be avoiding nest intrusion by other males (sunken eggs and/or embryos invariably die). Males may build additional nests during egg attendance, but attending males did not attract females (they did not call).

Electromyographic behaviour of the gastrocnemius muscle during knee extension and flexion performed on the leg press

The gastrocnemius was analysed in 10 male volunteers during knee flexion and extension with the foot in normal, plantar flexion and dorsal flexion positions. Hewlett-Packard surface electrodes, an electromyographic signal amplifier, a computer equipped with an AID conversion plaque (Model CAD 10/26), a software specially designed to record and analyse the signals, a horizontal leg press, and electrogoniometers were used. The gastrocnemius muscle showed strong potentials at the end of knee extension and beginning of knee flexion. The muscle presented a similar activity both in the zipper and lower platforms. As to bilateral action, the right gastrocnemius presented stronger potentials on the upper platforms, whereas the potentials were bilaterally similar on the lower platforms. As for foot position, the gastrocnemius presented strong potentials when the foot was in plantar flexion. The remaining positions had no effect on the work of the muscle.

Mechanical behaviour of strain aged dual phase steels

Dual phase steels, characterised by good formability and excellent surface finish, are suitable for applications where processing involves cold deformation. In this context an investigation has been conducted into the cold deformation aging susceptibility of carbon steel API-5L-B and microalloyed steel API-5L-X52, both with dual phase microstructures. Changes in mechanical properties such as phase microhardness, ultimate tensile strength, and yield strength in both types of steel were observed at aging temperatures of 25, 80, and 150°C. This aging is associated with dislocation structures formed on ferrite grains in the vicinity of ferrite/martensite interfaces during intercritical treatments, which become preferential sites for solute atom diffusion. © 1999 IoM Communications Ltd.

A thermal behaviour study of solid-state cinnamates of the latter trivalent lanthanides and yttrium(III)

Some new compounds of cinnamic acid with the latter trivalent lanthanides and yttrium(III) were synthesized in the solid state. The compounds have the general formula LnL3, where Ln represents trivalent Eu to Lu or Y ions and L is the cinnamate anion (C6H5-CH=CH-COO-). Thermogravimetry (TG), derivative thermogravimetry (DTG), differential scanning calorimetry (DSC), infrared absorption spectra and X-ray diffraction powder patterns were used to characterize and to study the thermal behaviour of these compounds. © 2002 Elsevier Science B.V. All rights reserved.

Synthesis, characterization and thermal behaviour of solid-state compounds of 4-methoxybenzoate with some bivalent transition metal ions

Solid-state M-4-MeO-Bz compounds, where M stands for bivalent Mn, Co, Ni, Cu and Zn and 4-MeO-Bz is 4-methoxybenzoate, have been synthesized. Simultaneous thermogravimetry-differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC), X-ray powder diffractometry, infrared spectroscopy, elemental analysis and complexometry were used to characterize and to study the thermal behaviour of these compounds. The results led to have information about the composition, dehydration, thermal stability and thermal decomposition of the isolated compounds. © 2005 Akadémiai Kiadó, Budapest.

Distribution of constitutive heterochromatin in two species of triatomines: Triatoma lenti Sherlock and Serafim (1967) and Triatoma sherlocki Papa, Jurberg, Carcavallo, Cerqueira & Barata (2002)

Triatoma lenti and Triatoma sherlocki are hemipterans that belong to the brasiliensis subcomplex. In triatomines, the constitutive heterochromatin pattern is species-specific and allows, in many cases, for the grouping of species. Thus, we cytogenetically analyzed T. sherlocki and T. lenti using C-banding, and we compared the results with previous ones obtained in other species of the brasiliensis subcomplex. Both species were found to have a male diploid chromosome number of 22 chromosomes (2n = 20A. +. XY) with heterochromatic blocks at one or both chromosomal ends of all autosomal pairs. During early meiotic prophase, they showed a large heteropycnotic chromocenter constituted by the association of both sex chromosomes plus two autosomal pairs and many heterochromatic blocks dispersed inside the nucleus. All of these cytogenetic characteristics are similar to those observed in other species of brasiliensis subcomplex, results which confirm the grouping of T. sherlocki and T. lenti within this subcomplex. However, we emphasize the importance of other approaches, such as molecular analysis, to confirm the placement of T. lenti within the brasiliensis subcomplex. © 2012 Elsevier B.V.

Thermal behaviour of α-hydroxyisobutyric acid, sodium α-hydroxyisobutyrate and its compounds with some bivalent transition metal ions

Synthesis, characterization and thermal decomposition of bivalent transition metal α-hydroxyisobutyrates, M(C4H7O 3)2·nH2O (M = Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II)), as well as the thermal behaviour of α-hydroxyisobutyric acid and its sodium salt were investigated employing simultaneous thermogravimetry and differential scanning calorimetry (TG-DSC), infrared spectroscopy (FTIR), TG-DSC coupled to FTIR, elemental analysis and complexometry. All the compounds were obtained as dihydrated, except the copper one which was obtained in the anhydrous state. The thermal decomposition of the anhydrous compounds occurs in a single or two steps and the final residue up to 235 C (Mn), 300 C (Fe), 305 C (Co), 490 C (Ni), 260 C (Cu) and 430 C (Zn) is Mn2O3, Fe2O3, Co3O 4, NiO, CuO and ZnO, respectively. The results also provided information concerning the ligand's denticity and identification of the gaseous products evolved during the thermal decomposition of these compounds. Copyright © 2013 Published by Elsevier B.V. All rights reserved.

Synthesis, characterization and thermal behaviour of solid-state compounds of folates with some bivalent transition metals ions

Solid-state M-L compounds, where M stands for bivalent Mn, Co, Ni, Cu and Zn and L is folate (C19H17N7O6), have been synthesized. Simultaneous thermogravimetry and differential scanning calorimetry (TG-DSC), X-ray powder diffractometry, infrared spectroscopy (FTIR), TG-DSC coupled to FTIR, elemental analysis and high-resolution continuum source flame atomic absorption spectrometry technique (HR-CS FAAS) were used to characterize and to study the thermal behaviour of these compounds. The results provided information concerning the composition, dehydration, thermal stability and thermal decomposition. © 2013 Akadémiai Kiadó, Budapest, Hungary.

Corrosion and tribocorrosion behaviour of Al-Si-Cu-Mg alloy and its composites reinforced with B4C particles in 0.05M NaCl solution

The corrosion behaviour of metal matrix composites (MMCs) is strictly linked with the presence of heterogeneities such as reinforcement phase, microcrevices, porosity, secondary phase precipitates, and interaction products. Most of the literature related to corrosion behaviour of aluminium matrix composites (AMCs) is focused on SiC reinforced AMCs. On the other hand, there is very limited information available in the literature related to the tribocorrosion behaviour of AMCs. Therefore, the present work aims to investigate corrosion and tribocorrosion behaviour of Al-Si-Cu-Mg alloy matrix composites reinforced with B4C particulates. Corrosion behaviour of 15 and 19% (vol) B4C reinforced Al-Si-Cu-Mg matrix composites and the base alloy was investigated in 0.05M NaCl solution by performing immersion tests and potentiodynamic polarisation tests. Tribocorrosion behaviour of Al-Si-Cu-Mg alloy and its composites were also investigated in 0.05M NaCl solution. The tests were carried out against alumina ball using a reciprocating ball-on-plate tribometer. Electrochemical measurements were performed before, during, and after the sliding tests together with the recording of the tangential force. Results suggest that particle addition did not affect significantly the tendency of corrosion of Al-Si-Cu-Mg alloy without mechanical interactions. During the tribocorrosion tests, the counter material was found to slide mainly on the B4C particles, which protected the matrix alloy from severe wear damage. Furthermore, the wear debris were accumulated on the worn surfaces and entrapped between the reinforcing particles. Therefore, the tendency of corrosion and the corrosion rate decreased in Al-Si-Cu-Mg matrix B4C reinforced composites during the sliding in 0.05M NaCl solution. © 2013 Elsevier B.V.