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- Author or Editor: J. A. García x
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Abstract
We have quantified the evolution during 1994 of the impact on the Tagus river of liquid releases of3H (51.3 TBq in the cited year), originating from the functioning of the Almaraz Nuclear Power Plant, and conditioned by the management of the cooling reservoir water. Taking into account, on the one hand, that tritiated water is hydrodynamically indistinguishable from untritiated water when both form part of the same mass of liquid, and, on the other, the practically null stratification and forced circulation of the water in the cited cooling reservoir, together with the hydrological fluxes interchanged between the said reservoir and the Tagus river (which is entirely regulated in the section under study and, because of prolonged drought, had a relatively small flow during the study period), we were able to model satisfactorily the temporal evolution of the3H activity in the cooling reservoir.
The thermal behaviour of some 2-benzylamino-2-deoxyheptonic acids obtained from 2-benzylamino-2-deoxy-D-glycero-L-gluco, 2-benzylamino-2-deoxy-D-glycero-D-ido and 2-benzylamino-2-deoxy-D-glycero-D-taloheptononitriles (reported) previously has been studied in air (static atmosphere) and N2 (dynamic atmosphere, flow rate 200 ml/min).
Thermal studies on metal complexes of 5-nitrosopyrimidine derivatives IV
Complexes of Fe(II), Co(II), Ni(II) and Cu(II) with 6-amino-5-nitrosouracil
The thermal decomposition processes of the complexes of 6-amino-5-nitrosouracil with Fe(II), Co(II), Ni(II) and Cu(II) have been studied using TG and DSC techniques. Dehydration energies have been calculated from the DSC curves.
The thermal behaviour of 6-amino-5-formyluracil (HFU), 6-amino-1-methyl-5-formyluracil (1-MFU), 6-amino-3-methyl-5-formyluracil (3-HFU) and 6-amino-1,3-dimethyl-5-formyluracil (HDFU) is described. Only HDFU is shown to contain crystallization water. Dehydration and fusion enthalpy values have been calculated from the DSC curves. Likewise, the thermal behaviour of new complexes obtained by reaction between the above pyrimidine derivatives and Ni(II), Cu(II) and Pd(II) ions is reported.
Abstract
The effect of silica nanofiller on the glass transition of a polyurethane was studied by DSC. The pristine polymer exhibits a single glass transition at about –10C. Uniform SiO2 spheres with different average sizes and narrow size distributions were synthesized in solution by the Stber method [1]. Both the effects of silica content within the polymer and particle size were investigated, as well as two different surface treatments. Scanning electron microscopy (SEM) clearly confirms the presence of the particles within the polymer matrix, showing uniform distribution and no agglomeration. While shifting of the glass transition has been reported by many authors, we have not seen any noticeable shift in this polymer. Surprisingly, we found no relevant effects when either increasing the filler content or changing the particle size. Different amounts of particles with average diameters of 175, 395 and 730 nm did not affect the glass transition temperature of the pristine polymer.
Abstract
Sol-gel zirconia was characterized using high-resolution thermogravimetry (Hi-Res TG) and differential scanning calorimetry (DSC) and compared with X-ray diffraction, Raman scattering, and UV-Vis spectroscopy. ZrO2-x(OH)2x·yH2O annealed below 400°C show typical behavior of amorphous material. As the annealing temperature is increased, the tetragonal and monoclinic phases crystallize. Typical Hi-Res TG curve shows that the samples are continuously dehydrated in a long temperature range, between room temperature and 600°C. The total mass loss relative to the initial mass is of about 29%. The DSC analysis coupled with TG and structural information, indicate that the exothermic processes about 355 and 447°C can be related to the nucleation process of the formation of tetragonal zirconia, with bulk crystallization at 447°C.
Abstract
Gamma exposure rate and radon levels were measured in 75 single-family dwellings in Mexico City in order to correlate them with local environment. Radon monitoring was performed both indoors and outdoors using a continuous working level monitor for short-lived radon decay products; the gamma exposure rate was measured using CaSO4: Dy+PTFE. The results obtained show a log-normal distribution. The mean indoor radon concentration is lower than 45 Bq/m3 and the mean indoor gamma exposure rate was 11.29 
R/h.
The best alternative for reducing citrus production costs is mechanization. Machine vision is a reliable technology for the automatic inspection of fresh fruits and vegetables that can be adapted to harvesting machines. In these, fruits can be inspected before sending them to the packinghouse and machine vision provides important information for subsequent processing and avoids spending further resources in non-marketable fruit. The present work describes a computer vision system installed on a harvesting machine developed jointly by IVIA and a Spanish enterprise. In this machine, hand pickers directly drop the fruit as they collect it, which results in an important increase of productivity. The machine vision system is placed over rollers in order to inspect the produce, and separate those that can be directly sent to the fresh market from those that do not meet minimal quality requirements but can be used by the processing industry, based on color, size and the presence of surface damages. The system was tested under field conditions.
There are two main theories explaining offspring sex biases in polygynous mammals. Trivers and Willard (1973) argue that mothers with greater reproductive resources should invest in the sex with the greater variance in reproductive success, usually sons. In contrast, because daughters in many polygynous mammals stay with their mother and compete with her for food, Local Resource Competition theory (e.g. Clark, 1978; Silk, 1983) predicts that the mothers with the greatest reproductive resources should invest in daughters. We investigated the strategy of sex allocation of a captive, outdoor population of 139 mouflon mothers, Ovis musimon, kept in a game state. A complex picture emerged in which, despite weight and body condition being correlated with age in female mouflons, mothers lambed more daughters with increasing age but also, within a given age, gave birth to more sons with increasing weight. Results may be useful in game management aimed at increasing the recruitment or quality o f males in managed populations.
The effect of sequential treatments of pressure (50–150 MPa, 10 ºC, 5 min) and temperature (57 ºC, 15 min) on the survival and bacteriocin production of Pediococcus acidilactici HA-6111-2 cells in the exponential growth phase was assessed. The growth curves were fitted with the modified Gompertz model, and the estimated maximum specific growth rate was considered to be pressure dependent. A delay in the maximum value of bacteriocin production was registered for more severe pressure conditions, but it was found more notorious for pressure followed by temperature treatments. At lower pressure intensity treatment, regardless of the application order, there was an enhancement of bacteriocin production per cell when compared to the control while maintaining the maximum production value. Bacteriocin production after the treatments can be described by an exponential model.
