Localization effects in transition-metal doped Bi2Sr2CaCu2O8+y high-temperature superconductors

Doping Bi₂Sr₂Ca₁Cu₂O_8+y with Co causes a superconductor-insulator transition. We study correlations between changes in the electrical resistivity _ab(T) and the electronic bandstructure using identical single crystalline samples. For undoped samples the resistivity is linear in temperature and has a vanishing residual resistivity. In angle resolved photoemission these samples show dispersing band-like states. Co-doping decreases T_c and causes and increase in the residual resistivity. Above a threshold Co-concentration the resistivity is metallic (d_ab/dT>0) at room temperature, turns insulating below a characteristic temperature T_min and becomes superconducting at even lower temperature. These changes in the resistivity correlate with the disappearance of the dispersing band-like states in angle resolved photoemission. We show that Anderson localization caused by the impurity potential of the doped Co-atoms provides a consistent explanation of all experimental features. The coexistance of insulating (d_ab/dT <0) normal state behavior and superconductivity indicates that the superconducting ground state is formed out of spatially almost localized carriers.     

Gender and dietary fat affect α-tocopherol status in F344/N rats

For four weeks, groups of eight male and eight female F344/N rats were fed diets containing 15.5, 20, 30 or 40% of energy (en%) as fat. The fat was composed of corn oil and beef tallow with 9 en% from linoleate in all diets. Females had greater mean hepatic α-tocopherol levels, whereas males had greater plasma α-tocopherol and cholesterol concentrations. In males, the plasma ratio of α-tocopherol/cholesterol was significantly greater than in females (P<0.05). Plasma α-tocopherol increased with increasing en% fat (r=0.51,P<0.001) in both sexes, but dietary fat did not alter hepatic α-tocopherol levels. These results suggest that plasma α-tocopherol may serve as a biomarker of total dietary fat intake and that in F344/N rats gender differences affect α-tocopherol and cholesterol status.     

Assessment of cerebral blood flow and CO2 reactivity after controlled cortical impact by perfusion magnetic resonance imaging using arterial spin-labeling in rats

We measured CBF and CO2 reactivity after traumatic brain injury (TBI) produced by controlled cortical impact (CCI) using magnetic resonance imaging (MRI) and spin-labeled carotid artery water protons as an endogenous tracer. Fourteen Sprague-Dawley rats divided into TBI (CCI; 4.02 +/- 0.14 m/s velocity; 2.5 mm deformation), sham, and control groups were studied 24 hours after TBI or surgery. Perfusion maps were generated during normocarbia (Paco2 30 to 40 mm Hg) and hypocarbia (PaCO2 15 to 25 mm Hg). During normocarbia, CBF was reduced within a cortical region of interest (ROI, injured versus contralateral) after TBI (200 +/- 82 versus 296 +/- 65 mL.100 g-1.min-1, P < 0.05). Within a contusion-enriched ROI, CBF was reduced after TBI (142 +/- 73 versus 280 +/- 64 mL.100 g-1.min-1, P < 0.05). Cerebral blood flow in the sham group was modestly reduced (212 +/- 112 versus 262 +/- 118 mL.100 g-1.min-1, P < 0.05). Also, TBI widened the distribution of CBF in injured and contralateral cortex. Hypocarbia reduced cortical CBF in control (48%), sham (45%), and TBI rats (48%) versus normocarbia, P < 0.05. In the contusion-enriched ROI, only controls showed a significant reduction in CBF, suggesting blunted CO2 reactivity in the sham and TBI group. CO2 reactivity was reduced in the sham (13%) and TBI (30%) groups within the cortical ROI (versus contralateral cortex). These values were increased twofold within the contusion-enriched ROI but were not statistically significant. After TBI, hypocarbia narrowed the CBF distribution in the injured cortex. We conclude that perfusion MRI using arterial spin-labeling is feasible for the serial, noninvasive measurement of CBF and CO2 reactivity in rats.     

Quantifizierende calciumspezies-analytik im wein zur frage der calciumstabilit?t

Zusammenfassung Die Calciumspezies-Stabilität als dekadischer Logarithmus der Komplex-Stabilitätskonstanten nach dem Massenwirkungsgesetz in Wein wird mit Hilfe der Direktpotentiometrie mit Ca-selektiver Elektrode (für die Calciumionenkonzentration) sowie der Photometrie (Ca-Gesamtgehalt) in 16 lager-stabilen Weinen (Ca-Gehalte zwischen 60 und 120 mg/l) mit 3,50±0,20 (Bereich 3,11–3,79) ermittelt. Durch Methodenvergleiche (Photometrie und AAS für Gesamtgehalte sowie Direktpotentiometrie und Ionenaustauschmethode für die Ionenkonzentration) wurden diese Ergebnisse abgesichert. Die Anwendung von Weinbehandlungsverfahren wie der Adsorption phenolischer Stoffe an Polyvinylpolypyrrolidin (PVPP) sowie der Ultrafiltration zur Abtrennung höhermolekularer Eiweißstoffe zeigte keine wesentlichen Veränderungen der Elementspezies-Stabilitäten. Bei einer Entsäuerung mit CaCO₃ oder nach der Doppelsalz-Entsäuerung wurde dagegen nicht nur ein Anstieg der Calciumgesamtgehalte auf 200 bis 535 mg/1 sondern auch eine deutliche Abnahme der Calciumspezies-Stabilität auf Werte von 2,2 bis 2,8 festgestellt. die nach dem Auskristallisieren von Calciumverbindungen nach einigen Wochen wieder Werte um 3 erreicht. Die Lagerstabilität eines Weines im Hinblick auf Calcium kann somit nach der Bestimmung der Calciumspezies-Stabilität beurteilt werden.

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Quantifying analysis of calcium species in wine from the point of view of calcium stability

Summary The stability of calcium species, expressed as the decadic logarithm of the complex stability constant after the chemical equilibrium had been established, was determined to be 3.50 ± 0.20 (range 3.11–3.79) by direct potentiometry with a calcium-selective electrode (for the calcium ion concentration) as well as photometry (total Ca content) in 16 storage-stable wines (Ca contents between 60 and 120 mg/1). By comparing the methods of photometry, AAS (for the total content) and direct potentiometry as well as ion-exchange method for ion concentrations, the results were verified. The treatment of the wine by the adsorption of phenolic substances on polyvinylpolypyrrolidine (PVPP) and by ultrafiltration for the separation of higher molecular proteins showed no significant changes in the stabilities of the calcium species. After deacidification with CaCO₃ or after salt deacidification had been performed twice, not only an increase in the total calcium content occured (200–535 mg/1), but there was also an evident decrease in the stabilities of the calcium species, which had values of 2.2–2.8 and reached values of 3 after crystallization of the calcium species. The storage stability of a wine, with respect to calcium, can be estimated after the determination of the stability of the calcium species.

     

Coaxial arrangement of a scanning probe and an X-ray microscope as a novel tool for nanoscience

We report on the design and first tests of a novel instrument aimed at combining the benefits of scanning force microscopy with those of X-ray spectroscopy. For this we built an instrument combining a scanning transmission X-ray microscope with a beam-deflection atomic force microscope in a coaxial geometry. This allows to combine X-ray absorption spectroscopy and high resolution topography in-situ. When replacing the conventional scanning probe tip by a coaxially shielded tip the instrument will allow detection of the photoelectrons produced by resonant X-ray absorption. This could yield spectroscopic information with a spatial resolution approaching the values achievable with atomic force microscopy.     

Lesser in vitro anaerobic cecal isoflavone disappearance was associated with greater apparent absorption of daidzein and genistein in Golden Syrian hamsters

Our hypothesis in this study was that in vitro disappearance of isoflavones from fecal or cecal contents of Golden Syrian hamsters paralleled the apparent absorption of these compounds, comparable with previous findings from in vitro human fecal incubations. Two studies were conducted to test this idea: one on in vitro fecal (study 1, n = 20/sex) and the other on in vitro cecal contents (study 2, n = 10/sex) ability to degrade isoflavones. According to HPLC analysis, urinary isoflavone excretion was significantly less by 2-4 fold in males compared with females in both studies. Fecal isoflavone excretion was not significantly different between sexes or isoflavones (study 1) and was <0.5% of ingested dose. In vitro anaerobic fecal isoflavone degradation rate constants from study 1 were minimal with no significant correlation between urinary and fecal isoflavone excretion. However, in vitro anaerobic cecal isoflavone degradation rate constants (study 2) were greater and significantly correlated with urinary excretion of daidzein (R = 0.90; p = 0.01) and genistein (R = 0.93; p = 0.004), but not glycitein (R = 0.50; p = 0.3). Both male and female hamsters showed a pattern of urinary isoflavone excretion similar to that found in humans (daidzein > genistein). Hamster in vitro cecal isoflavone degradation rate constants seemed to be analogous to human in vitro fecal isoflavone degradation rate constants for genistein and daidzein. The sex difference in isoflavone excretion in hamsters and the instability in glycitein excretion across studies coupled with the paucity of human data on this isoflavone deserve further investigation.     

Low linolenate and commercial soybean oils diminish serum HDL cholesterol in young free-living adult females

OBJECTIVE: A mutant soybean line (A16) low in linolenic acid content (2% of oil by weight) was developed to increase oil oxidative stability. It was unknown whether serum lipid and lipoprotein concentrations in humans would be affected should A16 soybean oil (A16 oil) replace commercial soybean oil in diets. This study was conducted to examine the hypothesis that in free-living normolipidemic women, the consumption of A16 oil at approximately 10% of energy intake (en%) would not affect serum lipids and lipoproteins differently than would the consumption of the same amount of a commercial soybean oil with 7% of linolenic acid content. DESIGN: Fifteen free-living female college students consumed the soybean oil daily with regular meals for 9 weeks in different orders, with each test oil being eaten for 3 weeks. During the study, 13 en% was provided by each test oil and a total of 35 en% was from dietary fat. Serum concentrations of total cholesterol, high-density lipoprotein cholesterol (HDL cholesterol), low-density lipoprotein cholesterol (LDL cholesterol) and triacylglycerides (TAG) were measured. Serum total fatty acid patterns were analyzed as well. RESULTS: Each of the three test oils decreased serum total cholesterol, LDL cholesterol and TAG concentrations from the baseline values. The feeding of A16 and commercial soybean oils decreased serum HDL cholesterol significantly compared with coconut oil (p < 0.05). Dietary inclusion of coconut oil increased serum myristic acid significantly more than did either soybean oil (p < 0.01). Serum arachidonic acid concentrations were significantly greater with A16 consumption than with commercial soybean oil consumption (p < 0.001). CONCLUSION: A16 and commercial soybean oils both diminished serum HDL cholesterol. Although the fatty acid composition differed between the two soybean oils, A16 oil and commercial oil had similar effects on serum concentrations of lipoproteins and lipids. With increased oxidative stability, A16 oil is a good alternative to commercial soybean oil.     

Migration of the uncemented Harris-Galante acetabular cup: results of the einbildroentgenanalyse (EBRA) method

Seventy primary total hip arthroplasties using the Harris-Galante acetabular cup (Zimmer, Warsaw, IN) were prospectively examined. Over the entire period of 65.4+/-7.8 months, radiologic migration analysis was performed using the Einbildroentgenanalyse (EBRA) method at an accuracy of 1 mm. Although there was clinically no suspicion of prosthetic loosening in any case, in 8 implants (11.4%) migration of more than 1 mm was observed. Cranial migration occurred in 3 cases (1.1, 1.3 and 1.6 mm), medial migration in 3 cases (1.1, 1.1, and 2.9 mm), and lateral migration in 2 cases (1.1 and 1.1 mm). In the other 62 cases, however, no migration was traceable. Compared with measurements of other implant systems by means of the EBRA method published recently by other groups, the migration rate of the Harris-Galante cup was without exception lower and provided excellent midterm implant stability.     

Real time monitoring of laser-induced thermal changes in cartilage in vitro by using snapshot FLASH

1. Removal of external K+ ions increases the amplitude of directly elicited twitch contractions of the mouse diaphragm (Nishimura et al., 1996). This increase depends on external Ca2+ ions. 2. We examined the effect of caffeine (2 mM) on this increase in twitch amplitude. The mouse diaphragm muscle was directly stimulated in the presence of d-tubocurarine (10 microM). 3. Caffeine increased the amplitude of twitches in a standard bathing solution. This effect was maintained in a solution without either K+ or Ca2+ ions but was abolished in a solution from which both ions were absent. Readdition of Ca2+ ions restored the potentiating effect of caffeine. 4. In the presence of caffeine, removal of both K+ and Ca2+ ions decreased the resting membrane potentials of muscle fibers to about -53 mV. The readdition of 2 mM Ca2+ ions restored the membrane potentials. 5. Twitch potentiation in the absence of external K+ ions was attenuated by 10 microM bepridil but not by 3 microM verapamil or 10 microM Cd2+ ions. 6. These results support the hypothesis that Na(+)-Ca2+ exchange can support twitch contraction during the inhibition of Na(+)-K(+)-ATPase activity. The influx of Ca2+ ions into the cells might be stored in the sarcoplasmic reticulum.