Effect of the curing régime on compressive strength

In a previous issue the Instituto Eduardo Torroja in Spain described the development of lightweight panels made from ordinary Portland cement and rice husk ash (RHA). This paper discusses the crucial effect of the curing régime on compressive strength with temperatures maintained at 30C and relative humidity at 80 percent.     

Resonant and non-resonant microwave absorption in the magnetoelectric YCrO3 through ferro-paraelectric transition

An electron paramagnetic resonance (EPR) study in the polycrystalline magnetoelectric YCrO₃ is carried out at X-band (8.8-9.8 GHz) in the 300-510 K temperature range. For all the temperatures, the EPR spectra show a single broad line attributable to Cr³⁺ (S = 3/2) ions. The onset of the ferro-paraelectric transition has been determined from the temperature dependence of three main parameters deduced from the EPR spectra: the peak-to-peak linewidth (ΔH_pp), the integrated intensity (I_EPR) and the g-factor; these parameters indicate a behavior in agreement with a diffuse phase transition. Low-field microwave absorption (LFMA) is used to give a further knowledge on this material; where this technique also gives evidence of the ferro-paraelectric transition.     

Thick unevenness compensation in a hot rolling mill havingautomatic gage control

Hot rolling products with improved quality features such as thickness profile, strip width, flatness and material mechanical properties, are in increasing demand. The project goal is to improve the production quality in an existing hot rolling mill at Aceralia Steel Company, Aviles, Spain. This paper describes the design and implementation of a supervisory system for real-time compensation of uneven thickness on both sides of a rolled strip. The design is based on a multivariable process model, whose parameters are calculated online using measurement data from the mill. As a result, a computer system was developed that corrects the automatic gage control output from online acquired mill operation data. Previously, this task was done manually and periodically by a human operator. Manual correction is tedious and error prone, since it is based on visual inspection. Moreover, the proposed method leads to notorious improvement in the output strip quality, as the correcting signal may be continuously applied before the uneven thickness effect is visible     

Studies of chromaffin granule functioning by flow cytometry: transport of fluorescent epsilon-ATP and granular size increase induced by ATP

Flow cytometry techniques, usually employed to characterize cellular populations, are reported here to be a valuable tool to approach the study of subcellular organelle functioning. Chromaffin granules rendered fluorescent by using an antibody against their membrane protein, synaptophysin, are detectable by flow cytometry. Moreover, these storage granules are able to transport the fluorescent ATP analogue, epsilon-ATP (1,N6-ethenoadenosine 5'-triphosphate), and the resulting granular fluorescence increase can also be followed by this technique. The saturation studies show a non-hyperbolic kinetic behaviour, with a two step curve. The K0.5 values were 0.26 and 2.5 mM and Hill numbers 1 and 6 respectively. In addition, an unexpected granular size increase, which was dependent on the epsilon-ATP concentration, occurred together with the fluorescence increase. Other nucleotide triphosphate substrates of V-ATPase, such as ATP or GTP, but not the non-hydrolyzable analogue ATP gamma S (adenosine 5'-O-(3-thiotriphosphate), mimic this effect, which exhibited sigmoidal saturation curves with K0.5 values of 1.8 and 3.1 mM for ATP and epsilon-ATP respectively. The V-ATPase inhibitors, suramin, EGTA or EDTA significantly reduced the granular size increase in the presence of ATP. Extragranular addition of noradrenaline has no effect by itself on the granular size, but significantly reduced the granular size increase induced by ATP. This effect was reversed by the amine transport inhibitor reserpine. The granular size increase induced by ATP was more effective in the presence of Cl- than Br- or I-. Moreover, no increase occurred in the presence of F- or acetate. The Cl- channel blockers were poorly effective, and only 2-(phenylamino)-benzoic acid (DPC) exhibited an effect on the ATP-induced granular size increase.     

Production of furfural by acid hydrolysis of corncobs

Hydrolysis of corncobs for producing furfural was carried out in a pressurized batch reactor using superheated water and diluted sulphuric acid as catalyst. The range of experimental conditions was T=140–200°C and P=350–1550 kPa. Yields of furfural are reported as a function of reaction temperature, particle size, acid concentration and liquid/solid ratio. Attention has been focused on the solid residue remaining after the hydrolysis process, so that it can be further used as a humic fertilizer after oxiammoniation treatment.     

Anatomic basis of continuous axillary block of the brachial plexus with thoracic reservoir

Although continuous axillary block is effective for periods of up to four to six weeks, pain clinic patients with severe chronic pain in the upper extremities, mainly resulting from neuropathic disease, can require continuous drug delivery by catheter-reservoir for up to three months or longer. We studied possible locations for implanting reservoirs or catheters from the perivascular axillary space in fresh cadavers, checking for possible vascular or nerve damage after applying the usual technique for reservoir implantation. The ideal location for the reservoir is the subcutaneous tissue of the homolateral infraclavicular space of the anterior side of the thorax. The customary procedures for inserting the catheter along the subcutaneous route that extends from the perivascular axillary space to the reservoir carry no risk of damaging vascular or nerve structures.     

The nutritional and health status of the Latin American woman

Latin America is a region where countries have various levels of socioeconomic development. Thus, the living standards and health status of its people differ significantly in the midst of a mosaic of social, ethnic, cultural and economic realities. Social inequalities and extreme poverty determine significant differences, not only in the magnitude of health indicators, but also in the type of pathology prevalent. People in the high socioeconomic levels are affected by nutritional diseases characterized by excessive food intake, while people from the low socioeconomic levels are affected by undernutrition and its associated pathology. Undernutrition occurs fundamentally among the age groups at higher risk in the population segments with low income, low food intake, illiteracy and poor access to the health care and preventive medicine centers. Among families exposed to undernutrition, women are usually in worse condition than men. This is due to the long working hours and the increased nutritional requirements caused by frequent gestations and prolonged lactation. It is estimated that one fourth of newborns in Latin America are affected by low birth weight, which has been associated to adolescent mothers, their excessive physical work, anemia, low maternal pregestational weight, low weight gain during gestation, and frequent maternal infections. Nutritional anemia due to iron deficiency is highly prevalent among pregnant women in Latin America. In some countries, the prevalence of folate deficiency during pregnancy appears to have increased significantly in the past 15 years and is becoming a nutritional problem that needs preferential attention. Diets generally are inadequate and, in the case of pregnant and lactating women, usually deficient in calories, protein, iron and folic acid. It is urgent that the health and nutritional status of Latin American women of low socioeconomic condition be given special attention, particularly mothers during gestation and lactation. Otherwise, women will not be able to altogether fulfill their important role in the home and within the family, nor will they successfully participate in the economic development of their countries.     

Pure yolk sack tumor of the testis in adults: report of a case]

Report of one case of pure yolk sack testicular tumour in an adult patient. This was a stage I case which had been under observation for 3 years without further evidence of disease. Several aspects related with this type of germinal, non-seminomatous tumour of the testicle are commented upon.