Optical and electrical properties of MoO2 and MoO3 thin films prepared from the chemically driven isothermal close space vapor transport technique

Chemically-driven isothermal close space vapour transport was used to prepare pure MoO₂ thin films which were eventually converted to MoO₃ by annealing in air. According to temperature-dependent Raman measurements, the MoO₂/MoO₃ phase transformation was found to occur in the 225 °C-350 °C range while no other phases were detected during the transition. A clear change in composition as well as noticeable modifications of the band gap and the absorption coefficient confirmed the conversion from MoO₂ to MoO₃. An extensive characterization of these two pure phases was carried out. In particular, a procedure was developed to determine the dispersion relation of the refractive index of MoO₂ from the shift of the interference fringes of the used SiO₂/Si substrate. The obtained data of the refractive index was corrected taking into account the porosity of the samples calculated from elastic backscattering spectrometry. The Debye temperature and the residual resistivity were extracted from the electrical resistivity temperature dependence using the Bloch-Grüneisen equation. MoO₃ converted samples presented a very high resistivity and a typical semiconducting behavior. They also showed intense and broad luminescence spectra composed by several contributions whose temperature behavior was examined. Furthermore, surface photovoltage spectra were taken and their relation with the photoluminescence is discussed.

Arsenic input into the catchment of the River Caudal (Northwestern Spain) from abandoned Hg mining works: effect on water quality

In Asturias (NW Spain) there are many abandoned mines, of which Hg mines are of particular significance from an environmental point of view, due to the presence of Hg and particularly As, which is found either in the form of specific (orpiment and realgar) or non-specific minerals (As-rich pyrite). The instability of these minerals leads to the presence of As-rich mine drainage and spoils heap leachates that enter surface waters or groundwaters. A study including the three most important Hg mines in the region (La Soterraña, Los Rueldos and El Terronal) has been conducted. Watercourses flowing through these mining areas are tributaries of the River Caudal, one of the most important rivers in the area. High concentrations of As were found in some of these waters, which were monitored over a period of three hydrological years and classified according to a water quality index. Those waters sampled close to the mines are generally of poor-to-bad quality, with low alkalinity and in some cases high metal content, but the quality of these waters improves with distance from the mines. The average mass load of As entering the River Caudal has been evaluated as: 200, 12 and 9,800 kg year(-1) from La Soterraña, Los Rueldos and El Terronal mine sites, respectively. Despite the constant input of about 10 tonnes of As per year, the total As concentration remains below analytical detection thresholds on account of the river's high water flow. Nevertheless, an important part of this As load is presumably retained in the river sediments, representing a potential risk of pollution of the aquatic ecosystems.

Karyological characterization of the endemic Iberian rock lizard, Iberolacerta monticola (Squamata, Lacertidae): insights into sex chromosome evolution

Rock lizards of the genus Iberolacerta constitute a promising model to examine the process of sex chromosome evolution, as these closely related taxa exhibit remarkable diversity in the degree of sex chromosome differentiation with no clear phylogenetic segregation, ranging from cryptic to highly heteromorphic ZW chromosomes and even multiple chromosome systems (Z1Z1Z2Z2/Z1Z2W). To gain a deeper insight into the patterns of karyotype and sex chromosome evolution, we performed a cytogenetic analysis based on conventional staining, banding techniques and fluorescence in situ hybridization in the species I. monticola, for which previous cytogenetic investigations did not detect differentiated sex chromosomes. The karyotype is composed of 2n = 36 acrocentric chromosomes. NORs and the major ribosomal genes were located in the subtelomeric region of chromosome pair 6. Hybridization signals of the telomeric sequences (TTAGGG)n were visualized at the telomeres of all chromosomes and interstitially in 5 chromosome pairs. C-banding showed constitutive heterochromatin at the centromeres of all chromosomes, as well as clear pericentromeric and light telomeric C-bands in several chromosome pairs. These results highlight some chromosomal markers which can be useful to identify species-specific diagnostic characters, although they may not accurately reflect the phylogenetic relationships among the taxa. In addition, C-banding revealed the presence of a heteromorphic ZW sex chromosome pair, where W is smaller than Z and almost completely heterochromatic. This finding sheds light on sex chromosome evolution in the genus Iberolacerta and suggests that further comparative cytogenetic analyses are needed to understand the processes underlying the origin, differentiation and plasticity of sex chromosome systems in lacertid lizards.

Isolation and characterization of polymorphic microsatellite markers in Iberolacerta monticola, and cross-species amplification in Iberolacerta galani and Zootoca vivipara

Fourteen polymorphic microsatellite loci are described for the Iberian rock lizard, Iberolacerta monticola. Genetic variation in a sample of 20 individuals from Piornedo (northwestern Spain) was quantified both by the number of alleles per locus, which ranged from six to 13, and by the expected frequency of heterozygotes under random mating (heterozygosity), which ranged from 0.761 to 0.902. Single locus and global exclusion probabilities were also computed, and indicate a high power of these markers for paternity assignments and mating system studies of I. monticola. All the analysed loci were also polymorphic in Iberolacerta galani, but only seven in Zootoca vivipara.

Ant colony algorithm implementation in electron and photon Monte Carlo transport: application to the commissioning of radiosurgery photon beams

PURPOSE

In this work, the authors describe an approach which has been developed to drive the application of different variance-reduction techniques to the Monte Carlo simulation of photon and electron transport in clinical accelerators.

METHODS

The new approach considers the following techniques: Russian roulette, splitting, a modified version of the directional bremsstrahlung splitting, and the azimuthal particle redistribution. Their application is controlled by an ant colony algorithm based on an importance map.

RESULTS

The procedure has been applied to radiosurgery beams. Specifically, the authors have calculated depth-dose profiles, off-axis ratios, and output factors, quantities usually considered in the commissioning of these beams. The agreement between Monte Carlo results and the corresponding measurements is within approximately 3%/0.3 mm for the central axis percentage depth dose and the dose profiles. The importance map generated in the calculation can be used to discuss simulation details in the different parts of the geometry in a simple way. The simulation CPU times are comparable to those needed within other approaches common in this field.

CONCLUSIONS

The new approach is competitive with those previously used in this kind of problems (PSF generation or source models) and has some practical advantages that make it to be a good tool to simulate the radiation transport in problems where the quantities of interest are difficult to obtain because of low statistics.

[The SUVIMAX (France) study: the role of antioxidants in the prevention of cancer and cardiovascular disorders]

The first ecological epidemiological studies revealed the possible preventive role of some foods which contain antioxidant compounds on cardiovascular disease and on some types of cancer. Nevertheless, later further research and the initial population-based supplementary tests at therapeutic doses have rendered contradictory results. To elucidate the cause-effect relationship of the antioxidant nutrients, the SU.VI.MAX study was considered in France. This is a prospective population-based study of randomized, double blind intervention, the prime objective of which is that of evaluating the effectiveness of a combination of antioxidant minerals and vitamins at nutritional dosages on the morbimortality by cancer and ischemic heart disease of a cohort of 12,749 volunteers of both sexes, ranging from 35 to 60 years of age, spread throughout France over an eight-year period. Likewise, an evaluation was also made of the impact of the supplement on the incidence of infectious disease, cataracts, the individual feeling of well-being and the use of health care resources, the biological markers of the vitamin and mineral status, the antioxidant activity, the immune condition and the evolution of the cardiovascular risk factors. The final points of this study are: the overall mortality, the specific mortality by cancer and/or ischemic heart disease, the incidence of cancer (of any type) and the incidence of ischemic heart disease. The assessment tools employed were: a monthly health questionnaire filled out telematically, a yearly clinical or analytical health check-up every other year, as well as the exhaustive monitoring and documentation of the adverse events and serious health problems. To ascertain the eating behavior and the evolution thereof in the individuals comprising the cohort, an eating survey was filled out twice a month. A description is provided of the means and methods employed in this study, the originality and magnitude of which entail unique aspects which serve to remedy some problems of nutritional epidemiology, as well as the strategies employed for maintaining the active collaboration of the cohort and the exhaustive monitoring thereof. Two years into this study, the consolidation of the monitoring organization and the low drop-out rate afford the possibility of anticipating that the SU.VI.MAX study is going to provide some answers of interest with regard to the relationship between antioxidants and good health.

Iron and folate status in Zairian mothers and their newborns

An evaluation of iron and folate status was carried out on 166 Zairian pregnant women from Kinshasa at delivery and in cord blood from their newborns. Anemia, defined as a low hematocrit value (less than 33%), was observed in 38% of pregnant women. Iron deficiency, recognized by a combination of abnormal values for serum ferritin level (less than or equal to 12 micrograms/l) and transferrin saturation (less than 16%) was present in 54% of pregnant women. Folate deficiency, defined by a red blood cell folate of less than 100 micrograms/l, was observed in 6% of cases. In anemic mothers, anemia was associated with iron deficiency in 57% of cases and with folate deficiency in 5%. Correlations between maternal and newborn iron and folate indicators were found. This study points out the necessity for developing strategies in African countries to combat nutritional anemias during pregnancy by specific measures combined with general strategies.

Effect of folic acid deficiency upon lymphocyte subsets from lymphoid organs in mice

1. Three groups of weanling C57BL/6 female mice were fed one of two folate-deficient diets (0 and 0.1 mg folic acid/kg diet) or a normal folate-containing diet (2 mg folic acid/kg diet) for 8 weeks. A control pair-fed group was introduced with the most severe folate-deficient diet. Seven mice were fed the 0 mg folic acid/kg diet for 8 weeks, then rehabilitated (R) on the 2 mg folic acid/kg diet for 10 days. 2. Mice fed 0 mg folic acid/kg diet were severely folate-deficient (SFD), whereas mice fed 0.1 mg folic acid/kg diet were moderately folate-deficient (MFD), as shown by their folate status parameters. 3. Thymus weight, thymocyte content and positive immature CD4+8+ cells were decreased in SFD mice compared to controls. These values were normalized after 10 days of rehabilitation. 4. Mesenteric lymph node cells were apparently not affected by folate deficiency. 5. The proportion of Thy-1+ splenocytes was mildly lower in SFD mice than in controls. In R mice, mean spleen weight and spleen cellularity were increased compared to the other groups, but the proportions of Thy-1+, CD4+8- and CD4-8+ cells were markedly lower than control values.

Bioavailable iron density in French and Spanish meals

Iron absorption from two typical French meals and three typical Spanish meals was measured, using the extrinsic tag technique (with 55Fe and 59Fe) on French and Spanish volunteers. The total iron absorption coefficient varied up to three-fold (between 3.4 and 11.4 per cent) according to the contents of haem and non-haem iron and the presence of non-haem iron absorption enhancers and inhibitors. Expressed for iron absorption of 40 per cent of the reference dose (corresponding to subjects with theoretical depleted iron stores), those coefficients varied up to four-fold (between 4.9 and 18.9 per cent). The bioavailable nutrient density ranged from 0.30 to 0.77 mg/1000 kcal in subjects with good iron stores and from 0.50 to 1.12 mg/1000 kcal for subjects with theoretical depleted iron stores. This low bioavailable iron density enabled understanding of why iron balance is especially critical in women of childbearing age in industrialized countries, where iron enrichment of food is not practised.

Effect of decreased food consumption during iron deficiency upon growth rate and iron status indicators in the rat

Weanling Wistar rats were given a low-iron diet (4-5 mg Fe/kg), a medium-iron diet (20 mg Fe/kg) or a control diet (40 mg Fe/kg) for 7 weeks. Pair-fed rats received the control diet in amounts equivalent to that consumed by animals on a low-Fe diet. Blood samples from the tail vein were taken after 4 weeks of diet and weekly during the following 3 weeks for determination of iron status parameters. Animals were weighed weekly. After 4 weeks of diet, the rats fed the 5 mg iron/kg diet were severely anemic and rats fed 20 mg iron/kg diet were moderately iron-deficient. Ad libitum and pair-fed controls had normal iron status. Total liver iron stores were lowest in anemic rats (p less than 0.001) and were also low in moderately iron-deficient animals (p less than 0.05). Growth rates decreased early in anemic and pair-fed rats. Both groups were smaller than controls and moderately iron-deficient rats after 2 weeks (p less than 0.05) and this continued until the end of the experiment (p less than 0.001). Body weights of pair-fed rats were lower than those of anemic rats from the 1st to the 3rd week of diet; thereafter, differences between the two groups were no longer significant.

[Measurement of sinoatrial conduction time]

A prolonged sinoatrial conduction time (SACT) is one of the electrophysiologic characteristics of sick sinus syndrome. Because conduction from the sinus node to the atrium can not be assessed directly, an indirect method for estimating the SACT was developed by Strauss et al.: the premature atrial stimulation technique. The theoretical basis of the method is reviewed and the use of atrial spontaneous premature beats is proposed to estimate the SACT instead of electrical premature atrial stimulation.

Nutritional anaemia in pregnant Beninese women: consequences on the haematological profile of the newborn

An assessment of iron and folic acid status, blood thick film and haemoglobin (Hb) electrophoresis was performed on 126 pregnant women (and their newborn infants) and in ninety-five menstruating women in Cotonou (Benin). Anaemia (according to the World Health Organization (1972] was observed in 55% of pregnant women and in 39% of menstruating women. Fe-deficiency was defined as a low serum ferritin concentration (12 micrograms/l or less), combined with a low transferrin saturation (less than 16%) or a high erythrocyte protoporphyrin level (more than 3 micrograms/g Hb), or both. A moderate elevation in the serum ferritin concentration (between 13 and 50 micrograms/l), associated with a low transferrin saturation or a high erythrocyte protoporphyrin level, or both, indicated Fe-deficiency in an inflammatory context. Fe-deficiency was present in 73% of pregnant women and in 41% of menstruating women. Folate deficiency (defined as erythrocyte folate below 160 micrograms/l) was observed in 45% of pregnant women. In pregnant women, anaemia was associated with Fe-deficiency in 83% of cases and with folate deficiency in 48% of cases. Haemoglobinopathies were mainly heterozygous and did not seem to contribute significantly to anaemia. Intensity of malaria was not related to Hb level, but Plasmodium falciparum was found in 99% of subjects. Hb concentration and mean corpuscular volume were significantly lower in babies born of Fe-deficient mothers than in babies born of Fe-sufficient mothers. Hb concentration in newborn infants was positively correlated with maternal serum ferritin.

[Assessment of the nutritional status of Algerian women in the reproductive age living in an urban, rural and semi-rural area]

We assessed the nutritional status of 302 menstruating women living in three urban, semi-rural and rural areas of eastern Algeria. The anthropometric data and the biochemical measurements (serum levels of total proteins, albumin, transferrin and prealbumin) have shown the absence of protein malnutrition and the evidence of problems of overweight, whatever the criterion used (body mass index or relative weight). There were no differences according to the residence. Anemia (defined by WHO references) was observed in 28% of urban women, 19% of semi-rural women and in 32% of rural women. Iron deficiency (defined by the association of serum ferritin level of 12 micrograms/l or less and transferrin saturation less than 15%) was observed in 29, 27 and 22% of the cases, respectively. Folate deficiency (defined by concentration of red blood cell folates of less than 100 micrograms/l) was observed in 48, 45 and 22% of cases, respectively. Finally, 81% of anemia were associated with biochemical evidence of iron and/or folate deficiency.

Relationship between anaemia, iron and folacin deficiency, haemoglobinopathies and parasitic infection

Iron status, folacin status, haemoglobinopathies, malarial infection and intestinal parasitosis frequencies were assessed in a representative sample of 586 subjects living in a rural district of South Benin. Anaemia according to WHO reference values for haemoglobin was observed in 42 per cent of subjects. The prevalence was higher in children and menstruating women. Iron deficiency, defined by two or more abnormal values in the four independent indicators of iron status used (transferrin saturation, erythrocyte protoporphyrin, serum ferritin, and mean corpuscular volume) was present in 30 per cent of subjects. Half of the anaemias were associated with iron deficiency. Folate deficiency was associated with anaemia in 20 per cent of subjects. Anaemia, iron and folacin status were not significantly related to the degree of malarial infection nor to the type of haemoglobin. Although hookworm infection was very common, there was no significant relationship between egg count and haemoglobin level or haematological parameters of iron and folacin status. The lack of correlation can be explained by the low wormload observed.

Factors affecting iron stores in French female students

Serum ferritin and haematological variables were determined in 476 healthy French students (21.3 +/- 0.2 years). Information was collected on the duration of menses and contraceptive uses. Dietary intakes were assessed by the dietary history method in a randomized subsample of 157 women. The proportion of anaemic subjects was low, but 16 per cent of women had exhausted iron stores (serum ferritin less than or equal to 12 micrograms/l). Duration of menses was negatively correlated with serum ferritin concentration. The mean iron intake was 10.92 +/- 0.02 mg/d. Only fewer than 5 per cent of the students had daily iron intakes corresponding to the recommended dietary allowances for menstruating women (greater than or equal to 16 mg/d). There was a positive correlation between energy consumption and iron intake (r = 0.79, P less than 10(-9) ). Tea and dairy products intakes appeared to have a significant negative correlation with serum ferritin. The positive correlation between serum ferritin and haemoglobin suggests that decreased or depleted iron stores are associated with suboptimal haemoglobin values. This raises the problem of the definition of normal serum ferritin and haemoglobin values in menstruating women.

Effects of iron supplementation on serum ferritin and other hematological indices of iron status in menstruating women

Serum ferritin, hemoglobin, serum iron and transferrin iron-binding capacity were evaluated in 107 healthy female students. 21 women had a serum ferritin of 12 micrograms/l or less, corresponding to an exhaustion of body iron stores. After 1 month of iron supplementation, significant increase of hemoglobin concentration and decrease of total iron-binding capacity were observed. Mean serum ferritin had increased from 24 to 41 micrograms/l, and all women had a serum ferritin above 12 micrograms/l. 1 month after the end of the trial, serum ferritin fell significantly. This study points out the problem of serum ferritin reference values and the definition of normal iron stores in menstruating women.

[Dietary iron intake in a population of French women of reproductive age]

Dietary iron intake has been estimated in 337 healthy, menstruating women, of high social conditions by dietary histories. The mean daily iron intake was 11 +/- 0.13 mg, of which 33% was supplied by meat and fish, whereas fruits and vegetables supplied 29%. The mean daily energy intake was 2,088 +/- 27 kcal (8,723 +/- 113 kJ). In 96.5% of the women, iron intake was lower than the Recommended Dietary Allowances (16-18 mg daily). There was a significantly positive correlation between energy intake and iron intake (r = 0.77; p less than 10(-9]. Therefore, the low iron intake may be considered as a consequence of a decrease in the energy intake observed during the last decades in industrialized countries. Iron fortification of one or several foods seems to be advisable to compensate, at least, partly iron intake deficiency.