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ABSTRACTA case study was conducted to evaluate the SO2emission reduction in a power plant in Central Mexico, as a result of the shifting of fuel oil to natural gas. Emissions of criteria pollutants, greenhouse gases, organic and inorganic toxics were estimated based on a 2010 report of hourly fuel oil consumption at the “Francisco Pérez Ríos” power plant in Tula, Mexico. For SO2, the dispersion of these emissions was assessed with the CALPUFF dispersion model. Emissions reductions of > 99% for SO2, PM and Pb, as well as reductions >50% for organic and inorganic toxics were observed when simulating the use of natural gas. Maximum annual (993 µg/m3) and monthly average SO2concentrations were simulated during the cold-dry period (152–1063 µg/m3), and warm-dry period (239–432 µg/m3). Dispersion model results and those from Mexico City’s air quality forecasting system showed that SO2emissions from the power plant affect the north of Mexico City in the cold-dry period. The evaluation of model estimates with 24 hr SO2measured concentrations at Tepeji del Rio suggests that the combination of observations and dispersion models are useful in assessing the reduction of SO2emissions due to shifting in fuels. Being SO2a major precursor of acid rain, high transported sulfate concentrations are of concern and low pH values have been reported in the south of Mexico City, indicating that secondary SO2products emitted in the power plant can be transported to Mexico City under specific atmospheric conditions.Implications: Although the surroundings of a power plant located north of Mexico City receives most of the direct SO2impact from fuel oil emissions, the plume is dispersed and advected to the Mexico City metropolitan area, where its secondary products may cause acid rain. The use of cleaner fuels may assure significant SO2reductions in the plant emissions and consequent acid rain presence in nearby populated cities and should be compulsory in critical areas to comply with annual emission limits and health standards.

The boundary element method, combined with the determination method for calcareous formation, was employed to optimize the cathodic protection (CP) system for the retrofit of an ASTM A36 (UNS K02600) carbon steel offshore platform. Based on the platform structure and anode distribution and consumption, a series of retrofitting schemes was evaluated to maximize CP for the entire structure. The optimization process provided an insight on how the distribution of anodes affects the structure-seawater potential and the life of the anodes. [ABSTRACT FROM AUTHOR]

AbstractObjective: To analyze clinical-biochemical correlations in newly diagnosed acromegaly, focusing in particular on patients with discrepant parameters. Design: Retrospective study. Methods: Data from 164 patients with acromegaly seen between 1995 and 2003. Patients were reviewed for the presence of headaches, arthralgias, hypertension, menstrual abnormalities, impotence, glucose intolerance or diabetes. Biochemical evaluation consisted of age- and gender-adjusted IGF-I levels and glucose-suppressed GH. Results: Magnetic resonance imaging (MRI) revealed macroadenoma in 127 patients and microadenoma in 37. Patients with macroadenomas were younger than those with microadenomas and the disease was more frequent in females. Excluding acral enlargement, which was present in all the patients, the most commonly reported complaints were headaches (66%) and arthralgias (52%). Hypertension was present in 37% of patients, whereas the prevalence of glucose intolerance and diabetes was 27 and 32%, respectively. Hyperprolactinemia was present in 20% of patients with microadenomas and in 40% of patients with macroadenomas. Hypogonadism was demonstrated in more than half of the patients and was not related to tumor size or prolactin level. Of all the clinical and metabolic abnormalities of acromegaly, only the presence of diabetes correlated with both basal and nadir post-glucose GH levels. Only 4 patients (2.4%) had glucose-suppressed GH values of <1 ng/ml in the presence of clinical evidence of acromegaly, an elevated IGF-I level and a pituitary adenoma on MRI. Conclusions: Clinical features of acromegaly correlate poorly with indices of biochemical activity. The prevalence of biochemically discordant acromegaly is considerably lower than recently reported.Copyright © 2004 S. Karger AG, Basel

Different electrochemical methodologies were established to induce general corrosion and blistering on homogeneous and heterogeneous carbon steel surfaces similar to the corrosion damage in a catalytic oil refinery plant. In one case, the film porosity and the iron sulphide stoichiometry were modified and in other case, the surface conditions were changed with sulphur films and microblisters. Additionally, we studied the influence of 1018 carbon steel surface conditions on the corrosion process in a medium simulating the average composition of sour waters in catalytic plants of PEMEX Mexico (0.1 M (NH4)2S, 10 ppm CN−as NaCN, pH 8.8). Using the impedance spectra, from 10 kHz to 0.01 Hz, it was possible to qualitatively identify the carbon steel surface condition in an alkaline sour environment and to suggest the same corrosion process steps for this system, despite different surface conditions: charge transfer resistance of steel oxidation in the metal/corrosion product film interface and Fe2+ion and H° diffusion through the corrosion product film. Finally, scanning electron microscopy of a freshly polished surface showed the formation of a homogeneous film immediately after introducing the carbon steel into the sour media. The other surface changes depended on the induced corrosion process and corroborated the electrochemical impedance predictions.

The MUREX (monitoring the usable soil reservoir experimentally) experiment was designed to provide continuous time series of field data over a long period, in order to improve and validate the Soil-vegetation-Atmosphere Transfer (SVAT) parameterisations employed in meteorological models. Intensive measurements were performed for more than three years over fallow farmland in southwestern France. To capture the main processes controlling land-atmosphere exchanges, the local climate was fully characterised, and surface water and energy fluxes, vegetation biomass, soil moisture profiles, surface soil moisture and surface and soil temperature were monitored. Additional physiological measurements were carried out during selected periods to describe the biological control of the fluxes. The MUREX data of 1995, 1996, and 1997 are presented. Four SVAT models are applied to the annual cycle of 1995. In general, they succeed in simulating the main features of the fallow functioning, although some shortcomings are revealed.

A group of 533 patients had cardiac valves replaced with homologous dura mater valves. The dura mater was preserved in a solution of 98 per cent glycerol and antibiotics for a period of 12 days before use. The leaflets were mounted in a stainless steel ring covered by Dacron velour. Two hundred forty-five patients had mitral valve replacement; 205 patients, aortic valve replacement; 17 patients, tricuspid valve replacement; and 2 patients, pulmonary valve replacement. Sixty-four patients were subjected to multivalvular replacements. The patients were followed for a period of 1 to 40 months after surgery with satisfactory clinical and hemodynamic results. Because 2 patients developed endocarditis produced by fungii, fungicidal drugs were added to the preservative solution. No bacterial endocarditis has been observed. No pressure gradient through the valve has been noted at rest. Anticoagulant drugs have not been used in the postoperative period.

Two trials were conducted with 66 cross-bred gilts during the late summer in 1960 and 1961, followed by a third trial with 35 gilts and 10 boars during the fall and winter of 1962–63 to study the effect of temperature on ovulation rate and early embryo survival to 25 days postbreeding. During each of the first two trials one group was maintained with natural shade on pasture, a second group was cooled at 60° F. and a third was kept in a heated room at 90° F. beginning 10 days postestrus until 25 days after breeding at the second estrus. One-half of the gilts were switched between the two temperatures at 3 days postbreeding.The average ovulation rate at second estrus for gilts on pasture, 90° F. and 60° F. temperatures was 15.1, 14.9 and 15.5, respectively. Differences were not significant. Conception rate was not different at these temperatures, although some gilts at 90° F. ovulated without showing estrus. Differences in number of live embryos due to all temperature treatments were not significant, although gilts maintained continuously at 90° F. averaged 10.9 embryos compared to 13.5 embryos for gilts at 60° F. Temperature up to 3 days postbreeding had no effect on number of embryos, whereas, gilts maintained at 90° F. from 3 days postbreeding had only 11.3 embryos compared to 13.6 for gilts at 60° F. (P<.05).Gilts in trial 3 maintained at 60° F. had 14.6 corpora lutea compared to 13.6 corpora lutea for those at 90° F. The average number of live embryos at 25 days was 11.7 at 60° F. and 10.4 at 90° F. in gilts bred to boars kept at the two temperatures. There were 0.9 more embryos in gilts bred to boars at 90° F. compared to gilts bred to boars at 60° F., indicating the high temperature did not reduce fertility of the boar.For all three trials there were 1.9 more embryos at 25 days postbreeding in gilts maintained continuously at 60° F. compared to gilts at 90° F. Cooling sows during periods of high temperature, especially soon after breeding, may increase embryo survival and subsequent litter size. It appears that an environmental temperature of 90° F. has less detrimental effect on fertility and embryo survival in gilts than in ewes.

Five patients that met the electrocardiographic criteria for left middle fascicular block underwent a cardiac electrophysiologic study and electrical endocardial mapping of both right and left ventricles. All patients also fulfilled the electrocardiographic criteria for left anterior fascicular block but no one showed right bundle branch block. The electrical endocardial mapping used the technical procedures described by Josephson et al. elsewhere. Comparisons between the points of endocardial activation to the right and left ventricle were made. The differences between these points are shown in Fig. 1 below. Notice that there are great differences of the activation time of the free walls of both ventricles. This is the result of a conduction delay in the regions 9, 10, 11, and 12 of the electrical endocardial mapping confirming the presence of that left middle fascicular block.