Low-temperature deposition of BaCuSF, a visible through mid-infrared p-type transparent conductor.

Barium copper sulfur fluoride (BaCuSF) is a p-type transparent conductor (p-TC) that, when doped with potassium, exhibits exceptionally high conductivity. The results of a detailed optical and electronic characterization of BaCuSF thin films deposited at a substrate temperature of 100 °C are presented. X-ray diffractometry shows the presence of a cubic BaCuSF phase. Spectroscopic measurements demonstrate that the films transmit from the visible through the mid-infrared with a band gap of 1.8 eV. Hall measurements indicate that the material is a degenerate semiconductor. As deposited, the films exhibit conductivity at room temperature of approximately 260 S/cm - among the highest reported room temperature conductivities for p-TCs. After post-deposition treatment in water, their conductivity increases to as high as 800 S/cm, and their band gap is reduced to 1.5 eV. The potential for low temperature deposition of p-type films with high conductivity and optical transmittance makes BaCuSF promising for several applications including flexible electronics and photovoltaics.

Waveguide amplifiers in sputtered films of Er3+-doped gallium lanthanum sulfide glass.

Waveguide amplifiers fabricated in Er3+-doped gallium lanthanum sulfide (GLS) glass are demonstrated. GLS is deposited onto fused silica substrates by RF magnetron sputtering, and waveguides are patterned by use of the lift-off technique. The waveguides exhibit a total internal gain of 6.7 dB (2.8 dB/cm) for a signal with a wavelength of 1.55 mum. This experiment is, to the best of our knowledge, the first demonstration of gain in an Er3+-doped chalcogenide glass waveguide. The fabrication methods we apply, if used with other rare earth dopants, could potentially be employed to produce sources operating in the mid-IR.

Time course of and effect of dietary iron level on iron incorporation into erythrocytes by infants.

As a part of our effort to explore various aspects of ferrokinetics in infancy, the present study was designed to determine the timing of entry of an orally ingested iron isotope into circulating erythrocytes, and the effect of the level of dietary iron [0.3 mg/100 kcal (418.4 kJ) vs. 1.8 mg/100 kcal] after isotope administration on erythrocyte incorporation of the isotope. We administered the stable isotope, (58)Fe, orally to 56-d-old and 168-d-old infants. All infants were fed a low-iron formula (LF) before and until 5 h after isotope administration. Thereafter, half the infants were fed a formula high in iron (HF group) while the remaining infants continued to receive the LF (LF group) for an additional 28 d. The quantity of (58)Fe in circulating erythrocytes increased from 14 to 28 d after isotope administration was nearly constant from 28 through 84 d of age (plateau value) and decreased between 84 and 112 d. Erythrocyte incorporation of (58)Fe was greater by the 168-d-old infants than by the 56-d-old infants, presumably because of the lesser iron stores of the older infants. In the 56-d-old infants, erythrocyte incorporation of (58)Fe was greater by the LF than by the HF group, but this difference was not significant in the 168-d-old infants. Thus, at least in younger infants, the level of iron intake after administration of an iron isotope affects erythrocyte incorporation of the isotope. The fact that less isotope was present in erythrocytes 112 d than 84 d after administration indicates that the life span of erythrocytes of infants, even beyond the immediate newborn period, is less than the 120-d life span of erythrocytes in the adult.

Less than 80% of absorbed iron is promptly incorporated into erythrocytes of infants.

Erythrocyte incorporation of an administered iron isotope has been used as a surrogate for iron retention on the assumption (validated in normal and iron-deficient adults) that 80-100% of the retained isotope is promptly incorporated into circulating erythrocytes. This assumption has not been validated in infants or children. The purpose of our study was to determine concurrently in normal infants absorption and erythrocyte incorporation of the stable isotope, (58)Fe. In a preliminary study (Study 1), we demonstrated that fecal excretion of ingested isotope occurs predominantly during the first 4 d after administration but continues beyond 7 d after ingestion, that is, beyond the point at which isotope in feces can be explained either by excretion of isotope that failed to enter enterocytes or by exfoliation of isotope-enriched enterocytes. In Study 2, we administered (58)Fe to nine younger (age 20-69 d) and nine older (age 165-215 d) term infants and collected feces for 11 d. Geometric mean retention of (58)Fe by the younger infants was 31.2% of intake at 4 d and 26.9% at 11 d, and by the older infants, 35.0% at 4 d and 32.5% at 11 d. Erythrocyte incorporation of (58)Fe 14 d after ingestion was 5.2% of the dose by the younger infants and 12.5% by the older infants. Utilization of retained (11 d) isotope thus was 19.8% by the younger infants and 38.3% by the older infants. We conclude that far less than 80% of retained isotope is promptly incorporated into erythrocytes (utilized) by infants.

Cow's milk and intestinal blood loss in late infancy.

OBJECTIVES: Young infants commonly show occult intestinal blood loss when fed cow's milk, but in older infants blood loss may be less common. This study examined intestinal blood loss in response to cow's milk feeding in normal 7(1/2)-month-old and 12-month-old infants. STUDY DESIGN: Infants (n = 62) were fed formula for 1 month and then pasteurized cow's milk for 2 months. Stools were collected for quantitative determination of hemoglobin. Iron nutritional status was assessed. RESULTS: Infants fed cow's milk from 7(1/2) months of age showed a significant increase in guaiac-positive stools and in stool hemoglobin concentration. These effects were largely limited to those infants who had been breast fed early in life. Infants fed cow's milk from 12 months of age at baseline had greater stool hemoglobin concentrations than 7(1/2)-month-old infants, but cow's milk produced no significant increase. In neither age group did cow's milk affect iron nutritional status. CONCLUSION: The response to cow's milk is attenuated in infants aged 7(1/2) months compared with younger infants. By 12 months of age, the response has disappeared entirely. We conclude that the gastrointestinal tract of healthy infants gradually loses its responsiveness to cow's milk.

Infant formula with protein-energy ratio of 1.7 g/100 kcal is adequate but may not be safe.

BACKGROUND: An adequate protein-energy ratio of infant formulas has been defined as one that permits growth similar to that of infants fed relatively generous protein-energy ratios, and serum concentrations of albumin and urea nitrogen no less than those observed in breast-fed infants. A safe ratio has been defined as one with no detectable adverse effects. The hypothesis was that a protein-energy ratio of 1.7 g/100 kcal is adequate and safe. METHODS: Healthy male infants were fed Formula 1.7, a milk-based formula, as the sole source of energy from the 8th to the 112th day of life. Weight, length, and energy intake were measured; serum albumin and urea nitrogen were determined; and the results were compared with data from appropriate reference groups of infants. RESULTS: Energy intake from 8 through 55 days was significantly higher than that of infants in the formula-fed reference group. Gain in weight was significantly more than that of the formula-fed reference group or of a breast-fed reference group, whereas gain in length was similar to that of the formula-fed reference group. Body mass index was significantly higher than that of either reference group, suggesting more fat accumulation in infants fed Formula 1.7. Plasma concentrations of albumin and urea nitrogen were similar to those of the breast-fed reference group. CONCLUSION: Infants fed Formula 1.7 received adequate intakes of protein. Because of the possibility that ad libitum feeding of diets with moderately inadequate protein-energy ratios is associated with increased food intake leading to excess weight gain, it is not possible to conclude that a protein-energy ratio of 1.7 g/100 kcal is safe.

Absorption of fat and calcium by infants fed a milk-based formula containing palm olein.

OBJECTIVE: The study tested the hypothesis that inclusion of palm olein (45% of fat) in the fat blend of a milk-based infant formula decreases the absorption of fat and calcium. METHODS: Formula PO contained palm olein (45%) in addition to soy, coconut and high-oleic sunflower oils (20%, 20%, and 15%, respectively); Formula HOS contained high-oleic safflower oil (42%) in addition to coconut and soy oils (30% and 28%, respectively) and no palm olein. Fat and calcium levels in the two formulas were similar. In a balanced crossover design, fat and calcium absorption were determined in 10 normal infants ranging in age from 22 to 192 days. In three infants metabolic balance studies with complete separation of urine and feces were performed, whereas in seven infants excreta were in part collected at home, resulting in incomplete separation of urine and feces. RESULTS: Mean (+/- SD) fecal excretion of fat was higher when Formula PO was fed than when Formula HOS was fed (0.55 +/- 0.29 vs. 0.09 +/- 0.04 g/kg/day; p < 0.001). Hence % fat absorption was lower with PO than with HOS (90.0 +/- 6.4 vs. 98.5 +/- 0.6% of intake; p < 0.01). The difference in percent fat absorption was explained by significantly (p < 0.05) lower % absorption of palmitic (16:0) and stearic (18:0) acids when Formula PO was fed than when Formula HOS was fed. Fecal excretion of calcium was higher with Formula PO than with Formula HOS (53.4 +/- 12.0 vs. 37.4 +/- 14.9 mg/kg/day; p < 0.01), and hence % calcium absorption was lower with Formula PO than with Formula HOS (37.5 +/- 11.5 vs. 57.4 +/- 14.9%; p < 0.001). CONCLUSION: Absorption of fat and calcium by normal infants is lower when palm olein provides a substantial proportion of formula fat than when formula does not contain palm olein.

Erythrocyte incorporation of iron is similar in infants fed formulas fortified with 12 mg/L or 8 mg/L of iron.

Although feeding of formulas with iron concentration of 215 mumol/L (12 mg/L) is a reliable means of preventing iron deficiency, high intakes of iron may adversely affect absorption of copper and zinc. Because data are not available to establish whether fortification at a lower level would result in equivalent iron absorption, we tested the hypothesis that iron absorption is greater by infants fed formulas with an iron concentration of 215 mumol/L (12 mg/L) than by those fed formulas with an iron concentration of 143 mumol/L (8 mg/L). Fifty-two normal infants entered the study at 112 +/- 4 d of age, and 46 of these were successfully studied until 196 d of age. Using the stable isotope 58Fe, we determined erythrocyte incorporation of iron by infants fed Formula 8 [iron approximately 143 mumol/L (8 mg/L)] and by infants fed Similac with Iron [iron approximately 215 mumol/L (12 mg/L)]. On each of three test days beginning at 154 d of age, a major portion of the formula was labeled with 58Fe. Geometric mean erythrocyte incorporation of iron adjusted for plasma ferritin concentration at 168 d of age was 4.82 mumol/d (0.269 mg/d) by infants fed Formula 8 and 5.21 mumol/d (0.291 mg/d) by infants fed Similac with Iron. Corresponding values at 196 d of age were 5.12 and 5.41 mumol/d (0.286 and 0.302 mg/d). The differences in quantity of iron incorporated into erythrocytes by infants fed Formula 8 and Similac with Iron were not statistically significant (P = 0.66 at 168 d of age, P = 0.75 at 196 d of age) and were judged to be nutritionally trivial. Because we were unable to provide support for our hypothesis that iron absorption is greater by infants fed formulas providing 215 mumol (12 mg) of iron per liter than by those fed formulas providing 143 mumol (8 mg) of iron per liter, we conclude that, pending the results of further studies, It is reasonable to decrease the iron concentration of iron-fortified infant formulas.

Palm olein in infant formula: absorption of fat and minerals by normal infants.

Palm olein, a low-melting fraction of palm oil, and soy oil can be combined to obtain fat blends with proportions of palmitic and oleic acids similar to those of human milk. We compared the absorption of fat and calcium by infants fed a formula containing a blend of palm olein (53%) and soy oil (47%) (Formula PO/S) with that by infants fed a formula containing a blend of soy oil (60%) and coconut oil (40%) (Formula S/C). In a randomized crossover design, one study was performed with each formula in each of 11 normal infants ranging in age from 27 to 161 d. Six of the infants were admitted for 72-h metabolic balance studies. In the other five infants, feces (with some admixture of urine) were collected at home for 96 h by using acid-washed cloth diapers. Mean (+/- SD) absorption of fat was 90.6 +/- 1.6% of intake when Formula PO/S was fed and 95.2 +/- 1.1% of intake when Formula S/C was fed; the difference was significant (P < 0.001). The difference in excretion of fat by infants fed the two formulas was explained by the difference in excretion of palmitic acid. Absorption of calcium averaged 39.0 +/- 8.3% of intake with Formula PO/S and 48.4 +/- 10.3% with Formula S/C; the difference was significant (P < 0.01). We conclude that fat is less well absorbed from a mixture of 53% palm olein and 47% soy oil than from a mixture of 60% soy oil and 40% coconut oil, and that absorption of calcium is less from a formula containing palm olein, presumably because of the formation of insoluble calcium soaps of unabsorbed palmitic acid.

Erythrocyte incorporation of iron by 56-day-old infants fed a 58Fe-labeled supplement.

In an effort to obtain information about absorption of supplemental iron by breast-fed infants during the early months of life, we determined erythrocyte incorporation of a stable iron isotope, administered to 56-d-old breast-fed infants in the form of a 58Fe-labeled vitamin-iron supplement. Infants of similar age fed a milk-based formula low in iron (approximately 4 mg/L) were also studied. The 58Fe-labeled vitamin-iron supplement was given between feedings. Fourteen days after administration of 58Fe, mean erythrocyte incorporation of the isotope was 7.8% of the dose by breast-fed infants and 4.4% of the dose by formula-fed infants. The feeding-related difference was statistically significant, probably reflecting the greater quantities of inhibitors of iron absorption in the intestines of formula-fed infants. With mean iron intake from the 58Fe-labeled vitamin-iron supplement of 7.99 mg for the breast-fed infants, erythrocyte incorporation of 7.8% of the dose corresponded to 0.62 mg, a value in the range of the estimated requirement for absorbed iron. We conclude that 2-mo-old breast-fed infants are able to absorb nutritionally significant amounts of iron from an iron supplement.

What is the safe protein-energy ratio for infant formulas?

Infants eat primarily to satisfy energy needs and the safe amount of protein in infant formulas (ie, the amount adequate for nearly all infants) is therefore expressed as the protein-energy ratio. We studied male infants aged 8-112 d fed milk-based formulas. One group (experimental group) was fed formulas that provided protein-energy ratios of 3.73 g/MJ (1.56 g/100 kcal) from 8 to 27 d of age, gradually decreasing to 2.99 g/MJ (1.25 g/100 kcal) from 84 to 111 d of age. Growth rates and serum albumin and urea nitrogen of these infants were compared with those of a concurrently studied control group and a previously studied large reference group. Gains in weight and concentrations of serum albumin of the three groups were not significantly different. Gains in length were significantly less for the experimental group than for the reference group. Serum urea nitrogen was significantly less in the experimental group than in the control group or reference group. We conclude that the protein-energy ratios of the experimental formula diet were below the safe level. Because the decrease in growth rate of the experimental group was rather small (demonstrable only in comparison with the large reference group), and because serum albumin of the experimental group increased with age as in normally nourished infants, we suspect that the safe protein-energy ratio of infant formulas lies closer to the ratios fed to the experimental group than to the ratio [approximately 5.0 g/MJ (2.1 g/100 kcal)] in currently marketed milk-based formulas.