The Kondo effect in the presence of ferromagnetism     

Pasupathy AN  Bialczak RC  Martinek J  Grose JE  Donev LA  McEuen PL  Ralph DC 《Science (New York, N.Y.)》2004,306(5693):86-89

We measured Kondo-assisted tunneling via C60 molecules in contact with ferromagnetic nickel electrodes. Kondo correlations persisted despite the presence of ferromagnetism, but the Kondo peak in the differential conductance was split by an amount that decreased (even to zero) as the moments in the two electrodes were turned from parallel to antiparallel alignment. The splitting is too large to be explained by a local magnetic field. However, the voltage, temperature, and magnetic field dependence of the signals agree with predictions for an exchange splitting of the Kondo resonance. The Kondo effect leads to negative values of magnetoresistance, with magnitudes much larger than the Julliere estimate.  相似文献   

Increasing rates of atmospheric mercury deposition in midcontinental north america   总被引：1，自引：0，他引：1  

Swain EB  Engstrom DR  Brigham ME  Henning TA  Brezonik PL 《Science (New York, N.Y.)》1992,257(5071):784-787

Mercury contamination of remote lakes has been attributed to increasing deposition of atmospheric mercury, yet historic deposition rates and inputs from terrestrial sources are essentially unknown. Sediments of seven headwater lakes in Minnesota and Wisconsin were used to reconstruct regional modern and preindustrial deposition rates of mercury. Whole-basin mercury fluxes, determined from lake-wide arrays of dated cores, indicate that the annual deposition of atmospheric mercury has increased from 3.7 to 12.5 micrograms per square meter since 1850 and that 25 percent of atmospheric mercury deposition to the terrestrial catchment is exported to the lake. The deposition increase is similar among sites, implying regional or global sources for the mercury entering these lakes.  相似文献   

Iron supplementation compliance among pregnant women in Bicol, Philippines     

Lutsey PL  Dawe D  Villate E  Valencia S  Lopez O 《Public health nutrition》2008,11(1):76-82

OBJECTIVE: To quantify factors influencing iron supplementation compliance and haemoglobin (Hb) concentrations among pregnant women participating in an iron supplementation programme under routine field conditions. DESIGN: Cross-sectional interviews and Hb measurements. SETTINGS: Albay and Sorsogon provinces, Bicol, Philippines. SUBJECTS: Three hundred and forty-six pregnant women receiving iron supplements via the Philippine iron supplementation programme. RESULTS: Women had a mean Hb concentration of 10.75 +/- 1.43 g dl-1, and 56.4% were anaemic (Hb < 11.0 g dl-1). On average, the first prenatal visit occurred at nearly 4 months (3.80 +/- 1.56). The ratio of visits to number of months pregnant was 0.51 +/- 0.24. Self-reported consumption of pills received was 85% (0.85 +/- 0.23), although pill counts suggested that consumption was 70% (0.70 +/- 0.35). Using multiple regression, an earlier first prenatal visit and greater self-reported compliance were positively associated with Hb concentrations. Additionally, perceived health benefits from taking the supplements and higher health programme knowledge were positively associated with pill consumption, while experiencing side-effects and disliking the taste of the supplements were associated with lower pill consumption. A greater number of living children was negatively associated with the frequency of prenatal visits. The number of children was also directly negatively associated with Hb concentrations. CONCLUSIONS: Compliance was positively related to Hb concentrations. Several factors associated with greater compliance were identified, including marital status, number of children, health programme knowledge, side-effects, perceived health benefits, and dislike of taste. Some of these factors may serve as avenues for interventions to increase compliance, and ultimately Hb concentrations.  相似文献   

Cyanidin 3-rutinoside and cyanidin 3-xylosylrutinoside as primary phenolic antioxidants in black raspberry     

Tulio AZ  Reese RN  Wyzgoski FJ  Rinaldi PL  Fu R  Scheerens JC  Miller AR 《Journal of agricultural and food chemistry》2008,56(6):1880-1888

Anthocyanin constituents in black raspberries (Rubus occidentalis L.) were investigated by HPLC-DAD, and their involvement as potent, significant antioxidants in black raspberries was demonstrated by three common antioxidant assays (FRAP, DPPH, ABTS) in this study. Five anthocyanins were present in black raspberries: cyanidin 3-sambubioside, cyanidin 3-glucoside, cyanidin 3-xylosylrutinoside, cyanidin 3-rutinoside, and pelargonidin 3-rutinoside. Their identities and structures, with particular emphasis on cyanidin 3-xylosylrutinoside, were confirmed by NMR spectroscopy. Two of these anthocyanins, cyanidin 3-rutinoside and cyanidin 3-xylosylrutinoside, predominated, comprising 24-40 and 49-58%, respectively, of the total anthocyanins in black raspberries. On the basis of both potency and concentration, cyanidin 3-rutinoside and cyanidin 3-xylosylrutinoside were found to be the significant contributors to the antioxidant systems of black raspberries. These findings indicate that these two anthocyanin compounds may function as the primary phenolic antioxidants in black raspberries. These two compounds exhibit potential biological activities that may be exploited in conjunction with other naturally occurring bioactive compounds in black raspberry fruit-based products used in clinical trials for the treatment of various types of cancer.  相似文献   

Baking performance of synthetic glycolipids in comparison to commercial surfactants     

Selmair PL  Koehler P 《Journal of agricultural and food chemistry》2008,56(15):6691-6700

To gain insight into structure-activity relationships of glycolipids in breadmaking monogalactosyl dilinoleylglycerol ( 8) and monogalactosyl monolinoleylglycerol ( 6) were synthesized. Then their functional properties in dough and breadmaking were compared to those of commercial surfactants such as lecithins (from soybean, rapeseed, and sunflower), diacetyltartaric acid esters of monoglycerides (DATEM), monoglycerides, and sodium stearoyl-2-lactylate. Chemical synthesis of the galactolipids consisted of a four-step reaction pathway, yielding amounts of 1-1.5 g suitable for the determination of the functional properties. Variation of the acylation time in the third step provided either the monoacyl ( 6) or the diacyl compound ( 8). The functional properties were determined by means of rheological and baking tests on a microscale (10 g of flour). The synthetic galactolipids both displayed an excellent baking performance, with 6 having by far the best baking activity of all examined surfactants. The baking activities of 8, DATEM, and the monoglycerides were in the same range, whereas sodium stearoyl-2-lactylate was less active. Although the lecithins gained similar maxima in bread volume increases as the synthetic surfactants did, considerably higher concentrations were required to do so. An antistaling effect was found for only 6 and not for 8. However, this effect was weaker than for sodium stearoyl-2-lactylate and the monoglycerides.  相似文献   

Effect of micro-oxygenation on color and anthocyanin-related compounds of wines with different phenolic contents     

Cano-López M  Pardo-Mínguez F  Schmauch G  Saucier C  Teissedre PL  López-Roca JM  Gómez-Plaza E 《Journal of agricultural and food chemistry》2008,56(14):5932-5941

Several factors may affect the results obtained when micro-oxygenation is applied to red wines, the most important being the moment of application, the doses of oxygen, and the wine phenolic characteristics. In this study, three red wines, made from Vitis vinifera var. Monastrell (2005 vintage) and with different phenolic characteristics, were micro-oxygenated to determine as to how this technique affected the formation of new pigments in the wines and their chromatic characteristics. The results indicated that the different wines were differently affected by micro-oxygenation. In general, the micro-oxygenated wines had a higher percentage of new anthocyanin-derived pigments, being that this formation is more favored in the wines with the highest total phenol content. These compounds, in turn, significantly increased the wine color intensity. The wine with the lowest phenolic content was less influenced by micro-oxygenation, and the observed evolution in the degree of polymerization of tannins suggested that it might have suffered overoxygenation.  相似文献   

Interferometric coupling of the Keck telescopes with single-mode fibers     

Perrin G  Woillez J  Lai O  Guérin J  Kotani T  Wizinowich PL  Le Mignant D  Hrynevych M  Gathright J  Léna P  Chaffee F  Vergnole S  Delage L  Reynaud F  Adamson AJ  Berthod C  Brient B  Collin C  Crétenet J  Dauny F  Deléglise C  Fédou P  Goeltzenlichter T  Guyon O  Hulin R  Marlot C  Marteaud M  Melse BT  Nishikawa J  Reess JM  Ridgway ST  Rigaut F  Roth K  Tokunaga AT  Ziegler D 《Science (New York, N.Y.)》2006,311(5758):194

Here we report successful interferometric coupling of two large telescopes with single-mode fibers. Interference fringes were obtained in the 2- to 2.3-micrometer wavelength range on the star 107 Herculis by using the two Keck 10-meter telescopes, each feeding their common interferometric focus with 300 meters of single-mode fibers. This experiment demonstrates the potential of fibers for future kilometric arrays of telescopes and is the first step toward the 'OHANA (Optical Hawaiian Array for Nanoradian Astronomy) interferometer at the Mauna Kea observatory in Hawaii. It opens the way to sensitive optical imagers with resolutions below 1 milli-arc second. Our experimental setup can be directly extended to large telescopes separated by many hundreds of meters.  相似文献   

Chemical composition and nutritional quality of soybean meals prepared by extruder/expeller processing for use in poultry diets     

Karr-Lilienthal LK  Bauer LL  Utterback PL  Zinn KE  Frazier RL  Parsons CM  Fahey GC 《Journal of agricultural and food chemistry》2006,54(21):8108-8114

This research examined variation in chemical composition and nutrient quality of soybeans (SBs) and soybean meals (SBMs) produced at seven commercial extruder/expeller plants in the United States (experiment 1), as well as differences in amino acid digestibilities when roosters were fed SBMs extruded at 121, 135, 150, or 160 degrees C at a U.S. pilot processing plant (experiment 2). In experiment 1, limited variation existed in the composition of SBs arriving at the plants, whereas substantial differences were noted in amino acid composition and protein quality of the resultant SBMs. In experiment 2, the SBMs extruded at 121 and 135 degrees C were underprocessed as noted by high urease activities and lower amino acid digestibilities. Soybean meals extruded at 150 and 160 degrees C resulted in higher amino acid digestibilities and lower urease activities, indicating adequate processing. Large variation exists in the nutritional quality of extruder/expeller SBMs currently in the marketplace. Optimal processing temperatures should be >135 degrees C, and temperatures as high as 165 degrees C do not result in overprocessing.  相似文献