Oxidative dissolution of research-grade minerals by Thiobacillus ferrooxidans and Thiobacillus thiooxidans

Solution- and solid-phase changes associated with galena (PbS) and sphalerite (ZnS) oxidation by T. ferrooxidans and T. thiooxidans, were determined. In experiments with galena, anglesite (PbSO4) was detected as a solid-phase product in biotic and abiotic experiments. In T. ferrooxidans cultures supplemented with FeSO4, jarosite [MFe3 (SO4)(2) (OH)(6)] was also detected as a new solid phase product, whereas SO was not detected in the residues. In sphalerite experiments, minor amounts of SO accumulated in FeSO4-amended sphalerite media with or without T. ferrooxidans or T. thiooxidans. Jarosite was only detected in T. ferrooxidans culture with FeSO4. By comparison with T. thiooxidans, T. ferrooxidans was more efficient in the oxidation of galena and sphalerite.

Enhancement of natural killer cell function by titanocenes in mice bearing Ehrlich ascites tumour

In the present work, we studied the effects of two titanocenes, biscyclopentadienyidichlorotitanium IV, (DDCT) and its derivative, biscyclopentadienylditiocianatetitanium IV (BCDT), on the activity of natural killer (NK) cells in Ehrlich ascites tumour (EAT)-bearing BALB/c mice. In order to investigate a more direct effect of these compounds on NK cell function, we performed experiments with severe combined immunodeficiency (SCID) mice, which exhibit a normal NK cell response in the absence of T and B cells. The treatment consisted of intraperitoneal (i.p.) administration of 15 mg/kg/day of DDCT for 2 days or 10 mg/kg/day of BCDT for 3 days. In addition, to verify whether the effects produced by the titanocenes were compound specific or related to a direct antitumour effect, we also investigated the effects of a 3-day treatment with 100 mg/kg of cyclophosphamide cyclophosphamide on NK cell activity. Our results demonstrated that, in BALB/c and SCID mice, NK cell function declined to subnormal levels after inoculation of the tumour. In these animals, although treatment with DDCT and BCDT significantly enhanced NK cell function, only DDCT restored NK cell activity to normal values in all stages studied. Conversely, treatment with cyclophosphamide reduced NK cell function in nontumour bearing SCID mice and was also unable to restore the decreased NK activity of tumour-bearing SCID mice, thus demonstrating that the enhancement of NK cell function by titanocenes is compound specific. The same effect of cyclophosphamide was observed with BALB/c mice. In the present study, the up-modulatory effects of these two compounds on NK cell function reveal a new aspect of the mechanism of antitumoural action of titanocenes. (C) 2003 Elsevier B.V. All rights reserved.

Immobilized cells of Acidithiobacillus ferrooxidans in PVC strands and sultite removal in a pilot-scale bioreactor

The biooxidation of ferrous ion into ferric ion by Acidithiobacillus ferrooxidans can be potentially used for the removal of H2S from industrial gases. In this work, Fe3+ ions were obtained through the oxidation of Fe2+ using the LR strain of At. ferrooxidans immobilized in PVC stands in a pilot-scale bioreactor, while H2S was removed in an absorption tower equipped with Rasching rings. At. ferrooxidans LR strain cells were immobilized by inoculating the bacterium in a Fe2+-mineral medium and percolating it through the support. After complete Fe2+ oxidation, which took around 90 h, the reactor was washed several times with sulfuric acid (pH 1.7) before a new cycle was started. Four additional cycles using fresh Fe2+ mineral medium were then run. During these colonization cycles, the time required for complete iron oxidation decreased, dropping to about 60 h in the last cycle. The batch experiments in the H2S gas removal trials resulted in a gas removal rate of about 98-99% under the operational conditions employed. In the continuous experiments with the bioreactor coupled to the gas absorption column, a gas removal efficiency of almost 100% was reached after 500 min. Precipitate containing mainly sulfur formed during the experimental trial was identified by EDX. (c) 2005 Elsevier B.V. All rights reserved.

Yield and quality of carrot seeds, cv. Brasilia, as a result of plant population, gibberellic acid and stage of maturity

'Brasilia' is a cultivar of carrot with characteristics suiting cultivation under hot conditions but with problems in seed production, arising from the conflicting requirements of root and seed production. One solution is to select cultivars requiring vernalisation and then to use GA(3) to induce flowering where the climate prevents this. There is, however, little information on plant population, seed maturity and harvesting time on which to base such a procedure. Accordingly this research was carried out to study the physiological quality and production of the seeds in plant populations from 25,000 to 800,000 plants/ha, in the seed-to-seed method of cv. Brasilia in Anapolis, GO, Brazil. In each population, two harvest methods (from first and second orders of umbels, or selected harvest, and remaining orders, or total harvest) and two stages of maturity (brownish, or mature seeds, and yellowish, or immature ones) were also evaluated. Two trials were carried out, with and without gibberellic acid. Seed was evaluated for physical characters, germination, vigour, 1000-seed weight, water content, dry matter and productivity. Seed was produced in both experiments (with or without GA3 spraying). Mature seed showed germination at least 30% greater than immature, and seed from the selected harvest showed germination 16% greater than from the total harvest. In increasing plant population to 200,000 plants/ha, seed quality was not affected, but productivity increased.

Tensile strength of radio frequency cold plasma treated PET fibers - Part 1: Influence of environment and treatment time

This article reports on a series of experiments with polyethylene terepthalate (PET) treated in a radio frequency plasma reactor using argon and oxygen as a gas fuel, for treatment times equal to 5 s, 20 s, 30 s, and 100 s. The mechanical strength modification of PET fibers, evaluated by tensile tests on monofilaments, showed that oxygen and argon plasma treatment resulted in a decrease in the average tensile strength compared with the untreated fibers. This reduction in tensile strength is more significant for argon plasma and is very sensitive to the treatment time for oxygen plasma. Scanning electron microscopy (SEM) used to analyze the effects of cold plasma treatment on fiber surfaces indicates differences in roughness profiles depending on the type of treatments, which were associated with variations in mechanical strength. Differences in the roughness profile, surveyed through an image analysis method, provided the distance of roughness interval, D-ri. This parameter represents the number of peaks contained in a unit length and was introduced to correlate fiber surface condition, before and after cold plasma treatments, and average tensile strength. Statistical analysis of experimental data, using Weibull cumulative distribution and linear representation, was performed to explain influences of treatment time and environmental effects on mechanical properties. The shape parameter, alpha, and density parameter, beta, from the Weibull distribution function were used to indicate the experimental data range and to confirm the mechanical performance obtained experimentally.

Accuracy assessment of a photogrammetric close-range reconstruction system

Geometric accuracy of a close-range photogrammetric system is assessed in this paper considering surface reconstruction with structured light as its main purpose. The system is based on an off-the-shelf digital camera and a pattern projector. The mathematical model for reconstruction is based on the parametric equation of the projected straight line combined with collinearity equations. A sequential approach for system calibration was developed and is presented. Results obtained from real data are also presented and discussed. Experiments with real data using a prototype have indicated 0.5mm of accuracy in height determination and 0.2mm in the XY plane considering an application where the object was 1630mm distant from the camera.

Design and ergonomics of package inserts of drugs in Brazil: a reality in construction

This research deals with the design of leaflets of medicines, evidencing the problems resulting from the lack of Brazilian normalization to promote the use of the graphical representation of instructional texts warnings. It approaches studies related to the effectiveness and efficiency of information systems, highlighting the semiotics and the cultural and informational ergonomics. The analysis of the context uses as method, an analytical study on selected warnings of thirty leaflets of medicines, followed by interviews lead with the public managers involved with the regulation of the pharmaceutical companies, and two experiments with users performed in city of Recife, in State of Pernambuco: one aiming at to identify how they interact with the leaflets of medicines, and the second one testing their understanding concerning standardized illustrations in the United States and the South Africa. The results show the need for improvements in presentation and graphic representation of leaflets of medicines, powering them to the role of communication, to ensure the consumption of medicine safely by its users. The conclusion congregates parameters and recommendations for the graphic representation of warnings in leaflets of medicines in Brazil.

The influence of cardiopulmonary bypass operation on the biodistribution of 99mTc-HMPAO-labelled granulocytes – Evaluation in pigs by planar scintigraphy and section-analyses

Aim of the study was to evaluate the influence of an extra corporal perfusion (cardiopulmonary bypass operation - cpb) on activation and biodistribution of Tc-99m labelled granulocytes in pigs with and without inhibition of the granulocytes by a leukocyte inhibition module (LIM). The cpb is often related to an activation of granulocytes resulting in an inflammatory answer. The biological mechanisms are unsolved yet. First trials of our group showed that LIM may inhibit the activation of neutrophils and therefore antagonize a cpb-caused impairment of cardiac function. This study is the continuation of these experiments with a higher number of animals and the focus on scintigraphic imaging. Animals, material, methods: 39 German landrace pigs were subdivided into three groups: group A (control) median sternotomy without cpb, group B with cpb, group C with LIM in addition to cpb. After labelling with Tc-99m-HMPAO autologues granulocytes were reinjected. Subsequently to cpb, the animals underwent scintigraphic imaging. Quantification was performed with ROI evaluation and with tissue samples (section analysis) examined in a well counter. Results:A high uptake of Tc-99m-HMPAO was found in the liver. The count rates in brain, heart, lung, spleen and kidneys were far below. The amount of Tc-99m-activity in the organ related to the half life corrected administered activity [%] was for the tissue samples (group A/B/C): brain 0.01/0.02/0.03; lung 12.1/8.3/11.5; heart 0.35/0.54/0.42; kidney 1.24/0.87/1.02; spleen 4.0/4.0/4.5, liver 16.8/20.9/19.6. The count rates determined by ROI-evaluation of the scintigraphic images related to the total count rate in the image [%] were (group A/B/C): brain 1.1/0.9/1.0; lung 15.6/10.4/12.2; heart 4.0/3.5/3.4; kidney 4.0/2.9/3.2; spleen 7.6/7.7/9.5, liver 23.1/36.7/31.4. A significant difference in the tracer uptake between the groups could neither be detected by scintigraphic imaging nor evaluation of tissue samples. Conclusion: Scintigraphic imaging as well as section analysis showed a comparable biodistribution of the tracer. Therefore, the initial results of our group were not confirmed with a considerably higher number of animals. Neither cpb nor the use of the LIM influenced distribution of Tc-99m-labelled granulocytes in pigs significantly.

Reprodução de Meloidogyne incognita, M. javanica e Pratylenchus coffeae em Diferentes Cultivares de Bananeira

Banana (Musa spp.) is one of the most consumed fruits in the world, and it is cultivated in many tropical countries. In Brazil, the productivity is low due to several factors such as the incidence of pests and diseases. The nematodes are among the most important problems found in the production of bananas. This research studied the reproduction of Meloidogyne incognita race 2, M. javanica and Pratylenchus coffeae in different cultivars of banana. The evaluation of the experiments with Meloidogyne spp. was carried out 120 days after the inoculation. The analyzed parameters were: number of gall, number of the external masses of eggs, number of eggs per gram of root, reproduction factor and number of juveniles in the soil. The evaluation of the experiment with P. coffeae was carried out 90 days after the inoculation; the final population was evaluated. The cultivars PV-0344, Maca, Grande Naine, FHIA 01, Thap Maeo and Prata Ana allowed greater multiplication of P. coffeae than Caipira, SH-3640 and FHIA-18. For M. javanica, the cultivars Calypso, Bucanneer, Grande Naine, PV-0344, Nanicao Magario, FHIA-02, SH-3640, Pacovan, and Prata Ana exhibited larger populations, decreasing in Maca. All cultivars allowed high multiplication rates of M. incognita.

Update on atmospheric neutrinos

We discuss the impact of recent experimental results on the determination of atmospheric neutrino oscillation parameters. We use all published results on atmospheric neutrinos, including the preliminary large statistics data of Super-Kamiokande. We reanalyze the data in terms of both vμ → vτ and vμ → ve channels using new improved calculations of the atmospheric neutrino flux. We compare the sensitivity attained in atmospheric neutrino experiments with those of accelerator and reactor neutrino oscillation searches, including the recent CHOOZ experiment. We briefly comment on the implications of atmospheric neutrino data in relation to future searches for neutrino oscillations with long baselines, such as the K2K, MINOS, ICARUS, and NOE experiments.

Characterization of the antinociceptive and sedative effect of amitraz in horses

Amitraz, an acaricide used to control ectoparasites in animals has a complex pharmacological activity, including α2-adrenergic agonist action. The purpose of this research was to investigate the possible antinociceptive and/or sedative effect of amitraz in horses. The sedative effect of the intravenous (i.v.) injection of dimethylformamide (DMF, 5 mL, control) or amitraz (0.05, 0.10, 0.15 mg/kg), was investigated on the head ptosis test. The participation of α2-adrenergic receptors in the sedative effect provoked by amitraz was studied by dosing yohimbine (0.12 mg/kg, i.v.). To measure the antinociception, xylazine hydrochloride (1 mg/kg, i.v., positive control) and the same doses of amitraz and DMF were used. A focused radiant light/heat directed onto the fetlock and withers of a horse were used as a noxious stimulus to measure the hoof withdrawal reflex latency (HWRL) and the skin twitch reflex latency (STRL). The three doses of amitraz used (0.05, 0.10 and 0.15 mg/kg) provoked a dose-dependent relaxation of the cervical muscles. The experiments with amitraz and xylazine on the HWRL showed that after i.v. administration of all doses of amitraz there was a significant increase of HWRL up to 150 min after the injections. Additionally, there was a significant difference between control (DMF) and positive control (xylazine) values up to 30 min after drug injection. On the other hand, the experiments on the STRL show that after administration of amitraz at the dose of 0.15 mg/kg, a significant increase in STRL was observed when compared with the control group. This effect lasted up to 120 min after injection. However, no significant antinociceptive effect was observed with the 0.05 and 0.10 mg/kg doses of amitraz or at the 1.0 mg/kg dose of xylazine.

Size effects in the magnetization of a superconducting wire

The size effects in the magnetization of a long cylindrical wire of circular cross section in the presence of an external magnetic field are investigated. For this study the London theory is used with boundary conditions appropriate for this geometry. Using the Monte Carlo simulated annealing method, the free energy of the mixed state is minimized with respect to the vortex positions. The ground state of the vortex lattice for n = 1 up to 18 vortices for a given radius of the cylinder is obtained. It is found that the finite size of the sample provokes a matching effect in the magnetization, as found in experiments with superconducting samples of finite size but different geometry. © 1999 American Institute of Physics.

Oxidative dissolution of covellite by Thiobacillus ferrooxidans

Oxidation of research-grade covellite was investigated in respirometric and growth experiments with Thiobacillus ferrooxidans. Covellite was directly oxidized by T. ferrooxidans in respirometric experiments, but the pH of mineral salts medium increased to prohibitively high values because of high sulfide concentrations. In glycine-H 2SO 4 buffered medium the pH remained steady and the oxygen uptake activity of T. ferrooxidans was not inhibited. In cultures growing with covellite as the sole source of energy, the pH increased to about 4. Redox potential increased to 500-600 mV during bacterial oxidation of covellite in the presence and absence of additional Fe 2+, whereas it remained mostly at about 350 mV in abiotic control. Jarosite was a major solid-phase product in T. ferrooxidans cultures. The solubilization of copper from covellite in inoculated flasks was higher than that obtained in control flasks and was not enhanced in the presence of additional Fe 2+.The sample also contained bornite (Cu 5FeS 4) which released iron in solution under all experimental conditions. Accumulation of S 0 was apparent only in inoculated covellite samples. © 1997 Elsevier B.V. All rights reserved.

Oxidative dissolution of chalcopyrite by Thiobacillus ferrooxidans

The oxidative dissolution of research-grade chalcopyrite was characterized in respirometric and growth experiments with Thiobacillus ferrooxidans. In respirometric experiments with chalcopyrite, the pH of mineral salts medium increased to values that inhibited the oxygen uptake activity of T. ferrooxidans. In glycine-H 2SO 4 buffered medium the pH remained stable and oxygen uptake was not inhibited. In cultures growing with chalcopyrite as the sole source of energy, pH changes were only minor during the incubation. The redox potential values increased to about 600 mV during the bacterial oxidation of chalcopyrite in the presence and absence of additional Fe 2+, while they remained at about 350 mV in abiotic control flasks. Iron in chalcopyrite was solubilized and oxidized to Fe 3+ by T. ferrooxidans. In the abiotic controls, by comparison, less iron was solubilized and it remained as Fe 2+. Jarosite was a major solid- phase product in T. ferrooxidans cultures. The solub'flization of copper from chalcopyrite in inoculated flasks was enhanced in the presence of additional Fe 2+.Accumulation of S 0, reflecting partial oxidation of the S-entity of chalcopyrite, was apparent from the x-ray diffraction analysis of solid residues from the inoculated flasks as well the abiotic controls. © 1997 Elsevier B.V. All rights reserved.

Line based camera calibration in machine vision dynamic applications

The problem of dynamic camera calibration considering moving objects in close range environments using straight lines as references is addressed. A mathematical model for the correspondence of a straight line in the object and image spaces is discussed. This model is based on the equivalence between the vector normal to the interpretation plane in the image space and the vector normal to the rotated interpretation plane in the object space. In order to solve the dynamic camera calibration, Kalman Filtering is applied; an iterative process based on the recursive property of the Kalman Filter is defined, using the sequentially estimated camera orientation parameters to feedback the feature extraction process in the image. For the dynamic case, e.g. an image sequence of a moving object, a state prediction and a covariance matrix for the next instant is obtained using the available estimates and the system model. Filtered state estimates can be computed from these predicted estimates using the Kalman Filtering approach and based on the system model parameters with good quality, for each instant of an image sequence. The proposed approach was tested with simulated and real data. Experiments with real data were carried out in a controlled environment, considering a sequence of images of a moving cube in a linear trajectory over a flat surface.