Recent theoretical proposals suggest that strain can be used to engineer graphene electronic states through the creation of a pseudo-magnetic field. This effect is unique to graphene because of its ...massless Dirac fermion-like band structure and particular lattice symmetry (C₃v). Here, we present experimental spectroscopic measurements by scanning tunneling microscopy of highly strained nanobubbles that form when graphene is grown on a platinum (111) surface. The nanobubbles exhibit Landau levels that form in the presence of strain-induced pseudo-magnetic fields greater than 300 tesla. This demonstration of enormous pseudo-magnetic fields opens the door to both the study of charge carriers in previously inaccessible high magnetic field regimes and deliberate mechanical control over electronic structure in graphene or so-called "strain engineering."
The influence of dietary CP on circulating LH and anterior pituitary and hypothalamic function was examined. In Exp. 1, 28 cows were randomly assigned to four treatment groups: adequate CP (ADQ; .96 ...kg/d) or deficient CP (DEF; .32 kg/d) beginning at 90, 60 and 30 d before parturition and continued at a 33% increase in feed consumption after parturition. Cows were bled at 15-min intervals for 8 h on d 20, 40 and 60 after parturition. Pituitaries were collected on d 62 to analyze GnRH receptor numbers and gonadotropin content. Frequency of pulsatile LH release increased (P less than .05) from 20 to 60 d in ADQ cows. Basal and mean LH were not affected (P greater than .10) by CP restriction or by days after parturition. Crude protein did not affect pituitary GnRH receptors (P greater than .10), but it did affect pituitary LH content, FSH content and FSH concentration (P less than .05). In Exp. 2, 28 cows were assigned to treatment groups as in Exp. 1. All cows were challenged with GnRH (.22 micrograms/kg BW) at 20, 40 and 60 d after parturition and were bled every 30 min for 6 h. Responsiveness to GnRH increased with increased time after parturition (P less than .07). Deficient CP decreased GnRH-induced LH release (P less than .05). In Exp. 3, 12 cows were randomly assigned to ADQ or DEF CP beginning 120 d before parturition. All cows received 1 mg estradiol-17 beta (E2) on d 19, 39 and 59 after parturition and were bled every 30 min for 14 h beginning 14 h following E2. Response to E2 was unaffected by CP restriction (P greater than .10), whereas time to E2-induced LH peak decreased as time after parturition increased in ADQ cows (P less than .05). Results suggest that delayed return to estrus in CP-deficient postpartum beef cows might be due to reduced gonadotropin release from the anterior pituitary and decreased anterior pituitary responsiveness to GnRH.
Many laboratories offer glycemic index (GI) services.
We assessed the performance of the method used to measure GI.
The GI of cheese-puffs and fruit-leather (centrally provided) was measured in 28 ...laboratories (n = 311 subjects) by using the FAO/WHO method. The laboratories reported the results of their calculations and sent the raw data for recalculation centrally.
Values for the incremental area under the curve (AUC) reported by 54% of the laboratories differed from central calculations. Because of this and other differences in data analysis, 19% of reported food GI values differed by >5 units from those calculated centrally. GI values in individual subjects were unrelated to age, sex, ethnicity, body mass index, or AUC but were negatively related to within-individual variation (P = 0.033) expressed as the CV of the AUC for repeated reference food tests (refCV). The between-laboratory GI values (mean ± SD) for cheese-puffs and fruit-leather were 74.3 ± 10.5 and 33.2 ± 7.2, respectively. The mean laboratory GI was related to refCV (P = 0.003) and the type of restrictions on alcohol consumption before the test (P = 0.006, r2 = 0.509 for model). The within-laboratory SD of GI was related to refCV (P < 0.001), the glucose analysis method (P = 0.010), whether glucose measures were duplicated (P = 0.008), and restrictions on dinner the night before (P = 0.013, r2 = 0.810 for model).
The between-laboratory SD of the GI values is ≈9. Standardized data analysis and low within-subject variation (refCV < 30%) are required for accuracy. The results suggest that common misconceptions exist about which factors do and do not need to be controlled to improve precision. Controlled studies and cost-benefit analyses are needed to optimize GI methodology. The trial was registered at clinicaltrials.gov as NCT00260858.
Algal polysaccharides such as carrageenan are good sources of dietary fibre. Previous studies have shown that carrageenan has hypoglycemic effects, but its cholesterol and lipid-lowering effects have ...yet to be demonstrated. In this study, carrageenan was incorporated into 4 food items, then fed to 20 human volunteers to determine its effects on blood cholesterol and lipid levels. The study followed a randomized crossover design. Each phase of the study--control and experimental--lasted for 8 weeks separated by a 2-week washout. At control, the subjects consumed their usual food intake; at experimental, they were given test foods with carrageenan partly substituting similar items in their usual diet. Fasting venous blood samples were collected immediately before and after each phase to assay serum cholesterol and triglyceride. The mean serum cholesterol was significantly lower (P<0.0014) after the experimental phase at 3.64 mmol/L compared with the mean level after the control phase, 5.44 mmol/L. The mean triglyceride level after the experimental phase, 0.87 mmol/L, was significantly lower (P<0.0006) in comparison to the level after the control phase, 1.28 mmol/L. The mean HDL cholesterol level significantly increased (P<0.0071) after the experimental phase at 1.65 mmol/L compared to the mean value after the control phase, 1.25 mmol/L. No significant differences were observed between the LDL cholesterol levels after the experimental and the control phases. This study indicates that regular inclusion of carrageenan in the diet may result in reduced blood cholesterol and lipid levels in human subjects.
Three high-amylose rice varieties, IR42, IR36, and IR62, with similar chemical composition including amylose content (26.7–27.0%), were cooked under the same conditions and tested for in vitro ...digestibility as well as blood glucose and insulin responses in healthy human volunteers. The starch-digestion rate and the glycemic and insulin responses were the highest in IR42, followed by IR36 and, then, IR62. The differences were not due to unabsorbed carbohydrate but were related to their physicochemical properties, such as gelatinization temperature, minimum cooking time, amylograph consistency, and volume expansion upon cooking. When the three varieties were cooked for their minimum cooking time, they had the same degree of gelatinization and their starch-digestion rates and glycemic responses were similar. We conclude that amylose content alone is not a good predictor of starch-digestion rate or glycemic response. Rice varieties with similar high-amylose contents can differ in physicochemical (gelatinization) properties and this, in turn, can influence starch digestibility and blood glucose response.
Five legumes including chick pea (Cicer arietinum Linn), pigeon pea (Cajanus cajan Linn. Huth.), black bean (Phaseolus vulgaris Linn), mung bean (Phaseolus areus Roxb) and white bean (Phaseolus ...vulgaris Linn) were cooked and tested for blood glucose response among healthy human volunteers. The blood glucose response to all legumes was significantly lower compared to bread. The glycaemic response to chick pea was significantly lower (P < or = 0.01) than that to black bean, pigeon pea and mung bean. The glycaemic index of chick pea (13.87 +/- 3.0) was significantly lower than those of black bean (27.91 +/- 4.0), pigeon pea (30.99 +/- 4.1) and mung bean (44.38 +/- 5.8) (P < 0.01) but was not different from that of white bean (19.48 +/- 4.9). The differences in the glycaemic responses among the legumes could be due to the differences in amount and kind of dietary fibre, amylose content and the presence of antinutrients. Legumes could therefore be added to the list of foods for diabetics and hyperlipidaemics and continuous consumption in larger amounts should be recommended to the general Filipino population.
High amylose rice variety was extruded to noodles and the starch digestibility and glycemic response of one healthy and two non-insulin dependent diabetic groups (Quezon City, Philippines and ...Toronto, Canada) with different habitual diets were determined. Rice extrusion significantly reduced the starch digestibility by 15% and the glycemic index in healthy volunteers by 36%. In both diabetic populations, the reduction in glycemic index was similar at 24%, suggesting that the affect was reproducible, and also that glycemic response was not affected by previous daily exposure of the subjects to rice. The effect of extrusion appears to be related to the starch gelatinization and retrogradation which occurred during processing as indicated by the lower amylograph viscosity and softer gel consistency of the rice noodles compared to the milled rice, as well as by the retrogradation test. The low glycemic response to high amylose rice and particularly the rice noodles suggests that these foods may have health benefits to both normal and diabetic individuals
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