An exploration of the relationship between bolometric luminosity and outflow velocity, for two classes of X-ray outflows in a large sample of active galactic nuclei has been performed. We find that line radiation pressure could be one physical mechanism that might accelerate the gas we observe in warm absorber, v~100-1000 km/s, and on comparable but less stringent grounds the ultra-fast outflows (UFOs), v~0.03-0.3c. If comparable with the escape velocity of the system; the first is naturally located at distances of the dusty torus, ~ 1 pc, and the second at sub-parsec scales, ~ 0.01 pc, in accordance with large set of observational evidence existing in the literature. The presentation of this relationship might give us key clues for our understanding of the different physical mechanisms acting in the center of galaxies, the feedback process and its impact on the evolution of the host galaxy.

We build a bulk velocity-dependent photoionization model of the warm absorber of the Seyfert 1 galaxy NGC 3783. By adopting functional forms for velocity of the flow and its particle density with radius, appropriate for radiation driven winds, we compute the ionization, temperature, line Doppler shift, and line optical depths as a function of distance. By doing this we obtain detailed profiles for the entire absorption line spectrum. The model reproduces the observed relationship between the gas ionization and the velocity shift of the line centroids as well as the asymmetry of the absorption lines in the X-ray spectrum of NGC 3783. It is found that the distribution of asymmetry requires the presence of two outflows: a higher ionization component responsible for the blue wings of the high ionization lines and the red wings of the low ionization oxygen lines, and a lower ionization flow that makes up for the blue wings of the oxygen lines. Our model predicts a relationship between the X-rays and the UV absorbers, where the component creating the long wavelength lines in the X-ray spectrum is also responsible for creating at least part of the UV absorption troughs.

We investigate the X-ray absorption structure of oxygen in the interstellar medium by analyzing XMM-Newton observations of the low-mass X-ray binary Sco X-1. Simple models based on the O i atomic photoabsorption cross section from different sources are used to fit the data and evaluate the impact of the atomic data on the interpretation of the observations. We show that relatively small differences in the atomic calculations can yield spurious results, and that the most complete and accurate set of atomic cross sections successfully reproduce the observed data in the 21.0–24.5 Å wavelength region of the spectrum. Our fits indicate that the absorption is mainly due to neutral gas with an ionization parameter of ξ = 10−4 erg cm s−1 and an oxygen column density of NO ≈ (8–10) × 1017 cm−2. The models are able to reproduce both the K edge and the Kα absorption line from O i which are the two main features in this region. We find no conclusive evidence for absorption by anything other than atomic oxygen.

Marine algae are easily produced and are good sources of Fe. If this Fe is bioavailable, algae consumption could help to combat Fe deficiency and anaemia worldwide. The objective of the present study was to evaluate Fe bioavailability, polyphenol content and antioxidant capacity from three species of marine algae distributed worldwide. A total of eighty-three subjects received maize- or wheat-based meals containing marine algae (Ulvasp.,Sargassumsp. andPorphyrasp.) in different proportions (2·5, 5·0 and 7·5 g) added to the water to prepare the dough. All meals administered contained radioactive Fe. Absorption was evaluated calculating radioactive Fe incorporation in subjects' blood. The three species of marine algae were analysed for polyphenol content and reducing power. Algae significantly increased Fe absorption in maize- or wheat-based meals, especiallySargassumsp., due to its high Fe content. Increases in absorption were dose-dependent and higher in wheat- than in maize-based meals. Total polyphenol content was 10·84, 18·43 and 80·39 gallic acid equivalents/g forUlvasp.,Porphyrasp. andSargassumsp., respectively. The antioxidant capacity was also significantly higher inSargassumsp. compared with the other two species analysed.Ulvasp.,Sargassumsp. andPorphyrasp. are good sources of bioavailable Fe.Sargassumsp. resulted in the highest Fe intake due to its high Fe content, and a bread containing 7·5 gSargassumsp. covers daily Fe needs. The high polyphenol content found inSargassumsp. could be partly responsible for the antioxidant power reported here, and apparently did not affect Fe absorption.

Searching for economical, nonconventional sources of iron is important in underdeveloped countries to combat iron deficiency and anemia. Our objective was to study iron, vitamin C, and phytic acid composition and also iron bioavailability from 4 species of marine algae included in a rice-based meal. Marine algae (Ulva sp, Sargassum sp, Porphyra sp, and Gracilariopsis sp) were analyzed for monthly variations in iron and for ascorbic acid and phytic acid concentrations. A total of 96 subjects received rice-based meals containing the 4 species of marine algae in different proportions, raw or cooked. All meals contained radioactive iron. Absorption was evaluated by calculating the radioactive iron incorporation in subjects' blood. Iron concentrations in algae were high and varied widely, depending on the species and time of year. The highest iron concentrations were found in Sargassum (157 mg/100 g) and Gracilariopsis (196 mg/100 g). Phytates were not detected in the algae and ascorbic acid concentration fluctuated between 38 microg/g dry weight (Ulva) and 362 microg/g dry weight (Sargassum). Algae significantly increased iron absorption in rice-based meals. Cooking did not affect iron absorption compared with raw algae. Results indicate that Ulva sp, Sargassum sp, Porphyra sp, and Gracilariopsis sp are good sources of ascorbic acid and bioavailable iron. The percentage of iron absorption was similar among all algae tested, although Sargassum sp resulted in the highest iron intake. Based on these results, and on the high reproduction rates of algae during certain seasons, promoting algae consumption in some countries could help to improve iron nutrition.

The objective of this study was to determine relative iron absorption from reduced iron-fortified Corn Flakes and the role of vitamins A and C improving absorption. The protocol included 87 subjects who received 4 meals composed of cereal, milk and sugar. Iron and different concentrations and combinations of vitamins A and C were added. Iron absorption was measured calculating radioactive iron incorporation into the blood of subjects. There was a significant 3.6-times increase in iron absorption when both vitamins were administered together. In vitro solubility tests with ferric chloride, electrolytic and reduced irons showed an important role of vitamins A and C enhancing iron solubility at pH 6 to the values found at pH 2. Addition of vitamins A and C to a ready-to-eat cereal significantly improves iron absorption by a process at least partially due, to the solubilyzing effect of these vitamins on reduced iron. Addition of both vitamins in the same meal produced an increment in absorption corresponding to the additive factor of each vitamin.

One hundred and seventy four human subjects were studied to find out the interaction of vitamin A or beta-carotene with the inhibitors of iron absorption, from a basal breakfast containing bread from either 100 g of precooked corn flour or 100 g of white wheat flour, 50 g of cheese and 10 g of margarine. Bread was labeled with either 55Fe or 59Fe. This bread was made from commercially flours fortified with iron as ferrous fumarate and vitamins. It was noticed that the percentage of iron absorption from the breakfast prepared with precooked corn flour given alone and with different concentrations of coffee was practically the same, while the iron absorption from the breakfast prepared from wheat flour decreased from 6% when the breakfast was given alone, to less than 2% when it was given with different concentrations of coffee. The only ingredient present in precooked corn flour and not in wheat flour was vitamin A. This difference encouraged the authors to perform further experiments using precooked corn and wheat flours fortified only with ferrous fumarate. These studies demonstrated that vitamin A inhibits the effect of the polyphenol and partially inhibits the effect phytate on iron absorption. HPLC and spectrophotometric studies demonstrated an interaction between vitamin A and iron. Other experiments, which included 100 volunteers, were performed to test the effect of vitamin A and beta-carotene on iron absorption from corn, wheat and rice. The presence of vitamin A increased iron absorption up to 3 times for rice, 2.4 times for wheat and 1.8 times for corn. beta-carotene increased absorption almost 3 times for the three cereals tested, showing that both compounds were capable of preventing the inhibitory effect of phytates on iron absorption. This information suggest that vitamin A and beta-carotene form a complex with iron keeping it soluble in the intestinal lumen and preventing the inhibitory effect of phytates and polyphenols on iron absorption.

This study was conducted to determine the bioavailability of iron amino acid chelate (ferrochel) added to fortify breads prepared from either precooked corn flour or white wheat flour + cheese and margarine compared with the same basal breakfast enriched with either ferrous sulfate or iron-EDTA. The inhibitory effect of phytate and polyphenols on iron absorption from ferrochel was also tested. A total of 74 subjects were studied in five experiments. Iron absorption from ferrochel was about twice the absorption from ferrous sulfate (P < 0.05). When ferrous sulfate and ferrochel were administered together or in different meals, absorption from ferrochel was about twice the absorption from ferrous sulfate (P < 0.05). Polyphenols present in coffee and tea inhibited iron absorption in a dose-dependent manner. American-type coffee did not modify iron absorption significantly, whereas both espresso-type coffee and tea reduced iron absorption from ferrochel by 50% (P < 0.05). Ferrochel partially prevented the inhibitory effect of phytates. Because of its high solubility in aqueous solutions even at pH 6, its low interactions with food and high absorption, ferrochel is a suitable compound for food fortification.

In searching for an explanation for the rapid response to iron-fortification programmes, we focused on the interaction of vitamin A and inhibitors of iron absorption from a basal breakfast containing bread from either pre-cooked maize flour or wheat flour plus cheese and margarine. These breads were labeled with either 59Fe or 55Fe. These experiments demonstrated that vitamin A prevented the inhibiting effect of polyphenols and phytates on iron absorption. It was also demonstrated that vitamin A had the same effect on iron absorption as phytase.

After the rapid decrease in the prevalence of iron deficiency and iron-deficiency anemia in the Venezuelan population when a national program for fortification of flours with iron and vitamins was instituted, we studied micronutrient interactions in Venezuelan diets. One hundred human adults were fed three cereal-based diets, labelled with either 59Fe or 55Fe in six studies. Each diet contained different concentrations of vitamin A (from 0.37 to 2.78 micromol/100 g cereal) or beta-carotene (from 0.58 to 2.06 micromol/100 g cereal). The presence of vitamin A increased iron absorption up to twofold for rice, 0.8-fold for wheat and 1.4-fold for corn. beta-carotene increased absorption more than threefold for rice and 1.8-fold for wheat and corn, suggesting that both compounds prevented the inhibitory effect of phytates on iron absorption. Increasing the doses of vitamin A or beta-carotene did not further significantly increase iron absorption. We measured the iron remaining in solution performing in vitro studies in which the pH of solutions was adjusted from 2 to 6 in the presence of vitamin A or beta-carotene. All of the iron from ferrous fumarate was soluble after changing the pH of the solution containing 3.4 micromol of beta-carotene to 6.0. Vitamin A was less effective. However, 78 +/- 18% of iron was soluble in the presence of 3.3 micromol of vitamin A, whereas with no vitamin addition, only 26 +/- 13% of iron was soluble (<0.05). Vitamin A and beta-carotene may form a complex with iron, keeping it soluble in the intestinal lumen and preventing the inhibitory effect of phytates and polyphenols on iron absorption.

The interaction of vitamin A and inhibitors of iron absorption from a basal breakfast containing bread from either 100 g of precooked maize flour or 100 g of wheat flour + 50 g of cheese + 10 g of margarine was studied. These breads were labeled with either 55Fe or 59Fe. This basal breakfast was given alone on the first day of the study, and a beverage containing coffee or tea at different concentrations was administered with this breakfast on the following days. In the first three experiments performed, the bread was made from commercially available flours, fortified with iron as ferrous fumarate and vitamins. It can be noticed that whereas the iron absorption from the breakfast containing wheat bread was significantly reduced when given with different concentrations of coffee beverages, the bioavailability of iron from the breakfast containing precooked maize bread remained the same in spite of being administered with increasing concentrations of coffee beverages. The only ingredient present in precooked maize bread and not in wheat bread was vitamin A. In the other experiments, iron and vitamin A were added to the non-fortified precooked maize flour in our laboratory. In presence of vitamin A, nonheme iron absorption from the basal breakfast containing either coffee or tea was not statistically different from the breakfast without coffee, meaning that vitamin A can overcome the inhibition of coffee and tea on iron absorption and also prevents the inhibitory effect of phytates. The high performance liquid chromatography and spectrophotometric studies seem to indicate that during the digestive process, iron and vitamin A form a new prouct or complex, that keeps iron soluble even at pH6. All these data suggest that vitamin A binds iron liberated during digestive process and acts as a quelating agent, keeping iron soluble in the intestinal lumen and preventing the inhibition of polyphenols and phytates on nonheme iron absorption.

The present study was undertaken to characterize the effect of heat on iron compounds and iron-containing proteins of rabbit meat. We also studied human iron absorption from beef meat precipitates and investigated changes in the cysteine content in beef and rabbit meat caused by cooking processes. Supernatant and precipitate fractions were obtained by an extraction procedure that included homogenization and repeated centrifugations. A 50% decrease of soluble iron was produced by cooking the meat. Cooking also reduced the heme iron content of the meat by 62%. Chromatographic separation of soluble meat extracts showed changes in ferritin, hemoglobin, and myoglobin elution profiles in cooked meat compared with raw meat. Determinations of the cysteine content in raw or cooked meat samples showed a statistically significant reduction (P < 0.0001) in the cysteine content in cooked samples compared with raw counterparts. Iron absorption studies in humans feeding the subjects with a typical beef-containing diet, which contained 60% of meat iron as heme iron, showed a 13.5% absorption from heme iron and a 6.3% from nonheme iron. The subjects fed with a diet containing beef precipitate in which only 30% of meat iron was heme iron showed a 7.6% absorption from heme iron and 7.5% from nonheme iron. These results show that although there are important changes in iron-containing proteins, heme iron, cysteine content, and iron absorption by cooking procedures, the factor present in meat responsible for enhancing nonheme iron absorption is not affected by heat and is still present in insoluble meat precipitates.

The iron bioavailability from three typical diets consumed by socioeconomic stratum IV (SES IV--working class) of the Venezuelan population was determined by the extrinsic label method. Although the iron content of the SES IV diets was about the same (250 mumol/d) as that of upper (SES I-III) and lower (SES V) socioeconomic strata diets, iron-replete subjects absorbed 43 and 61% more iron from the SES I-III diets than from the SES IV and V diets, respectively, and absorption from the main meal of the SES I-III diets was 100% greater. However, iron deficient subjects absorbed about the same amount of iron (45 mumol/d) from the SES IV diets as from the SES I-III diets. The SES I-III diets contained more iron absorption enhancers (ascorbic acid and meat protein) and less of the inhibitor phytate, than the SES IV and V diets. Iron absorption from the meals of four diets consumed at different times during the day was also measured. There was no significant difference in the percentage iron absorption from the same meals eaten in the morning after an overnight fast, and when eaten at the customary time of day.

The possibility of improving the dietary value of precooked maize flour through fortification with 11% coarse defatted maize germ was investigated. The results of tests in humans presented here show that the total iron absorption from the fortified preparation is similar to that from the precooked maize alone, but with the advantage of being richer in several nutrients: protein (25%), zinc (61%), potassium (47%) and magnesium (112%), as well as fiber (34%). Fortification lowers (by 20%) rather than raises the cost of the flour, and may be an important contribution to the diet of those populations where maize bread is a major component of the diet.

Pre-cooked maize flour was used as food vehicle to test the absorption of several iron compounds (ferrous sulfate, electrolytic iron, monoferric EDTA, and ferrous fumarate) with the aim of choosing the most adequate for programs of iron fortification for the prevention of iron deficiency. Seventy-three subjects volunteered to participate in this study. Ferrous sulfate showed fast denaturation when mixed with the flour and stored. The electrolytic iron showed that its absorption is independent from the nonheme iron pool and its relative bioavailability is about 54% of that observed with the same amount of ferrous sulfate.The relative bioavailability of monoferric EDTA was more than twice the absorption from ferrous sulfate but the utilization of this compound has been discouraged because of its already high consumption by food and drug technological procedure. The organoleptic test, the plasma iron tolerance and the bioavailability of ferrous fumarate recommended this iron salt as the most adequate to be used for fortifying pre-cooked maize flour.

Iron bioavailability was determined by the extrinsic label method in seven diets consumed by low, middle, and high socio-economic strata of the Venezuelan population. The results were compared with physiologic iron requirements and the prevalence of iron deficiency according to age and sex of others in the same strata. The iron metabolic balance obtained by comparing the iron absorption from diets with the physiologic iron requirement was negative in subjects consuming the low-bioavailability diets, being more marked in children below four years of age, and in adolescents and adult females. These groups also showed the highest prevalence of iron deficiency with and without anaemia. The metabolic iron balance in subjects consuming high iron-bioavailability diets was less negative among vulnerable groups consuming low-bioavailability diets and positive in the age and sex groups less vulnerable to iron deficiency. This information was used to identify the principal categories of dietary iron bioavailability in various regions of the world and their effect on the prevalence of iron deficiency.

The percent absorption of iron from four dietary sources was compared in 2018 human subjects with three indicators of iron status, serum ferritin concentration, percent saturation of plasma transferrin and iron absorption from a reference dose of ferrous sulfate. Higher correlation coefficients (r) were obtained by comparing dietary iron absorption with the reference dose absorption rather than with serum ferritin; for example, r = +0.61 and r = -0.38, respectively, for a meat and vegetable meal. However, in practice serum ferritin is almost as efficient as the reference dose absorption in estimating dietary iron absorption, because the 95% confidence limits calculated from the regression equations were very similar. The values of r calculated for iron absorption versus transferrin saturation were comparable to those obtained with the other indicators only in the range of transferrin saturation values below 25%, whereas in more iron-replete subjects (transferrin saturation > 25%), this correlation virtually disappeared. This indicates that, although both serum ferritin and transferrin saturation reflect iron status in irondepleted subjects, the control of iron absorption in ironreplete subjects is more dependent on iron stores as reflected in the serum ferritin concentration than the percent saturation of transferrin.