Search

Scope This study investigates the effect of the sweetness of a sucrose versus an isocaloric glucose solution in dietary concentrations on blood glucose regulation by adjusting the sweetness level using the sweet taste inhibitor lactisole. Methods and Results A total of 27 healthy males participated in this randomized, crossover study with four treatments: 10% glucose, 10% sucrose, 10% sucrose + 60 ppm lactisole, and 10% glucose + 60 ppm lactisole. Plasma glucose, insulin, glucagon‐like peptide 1, and glucagon levels are measured at baseline and 15, 30, 60, 90, and 120 min after beverage consumption. Test subjects rated the sucrose solution to be sweeter than the isocaloric glucose solution, whereas no difference in sweetness is reported after addition of lactisole to the sucrose solution. Administration of the less sweet glucose solution versus sucrose led to higher blood glucose levels after 30 min, as reflected by a lower ΔAUC for sucrose (1072 ± 136) than for glucose (1567 ± 231). Application of lactisole leads to no differences in glucose, insulin, or glucagon responses induced by sucrose or glucose. Conclusion The results indicate that the structure of the carbohydrate has a stronger impact on the regulation of blood glucose levels than the perceived sweetness., The effect of the sweetness of a sucrose versus an iso‐caloric glucose solution on blood glucose regulation by adjusting the sweetness using the sweet taste inhibitor lactisole is investigated. Sucrose is rated sweeter than an iso‐caloric glucose solution. The difference in the structure of glucose and sucrose, but not the perceived sweetness affects the blood glucose regulation in male subjects.

A setup for the preparation of oriented Au(111)/mica thin films of ∼100 nm thickness as an active substrate for graphene nanoribbon growth is shown. Low-energy electron diffraction shows that the Au(111) thin films have a single crystallographic orientation over the whole surface area. Graphene nanoribbons are synthesized by the bottom-up approach via surface polymerization of precursor molecules that are evaporated onto the catalytically active Au(111)/mica substrate. The graphene nanoribbons are investigated by a combination of resonance Raman, X-ray photoemission spectroscopy, and near-edge X-ray absorption fine structure spectroscopy confirming a nanoribbon quality equal to nanoribbons grown on commercially available single-crystal Au(111) substrates. The present work, therefore, establishes the insitu preparation of Au(111)/mica as an inexpensive and simple method to prepare substrates of desired shape and thickness for surface polymerization reactions which are of interest to a growing community of researchers working on graphene nanoribbons.

A semiconductor-to-metal transition in N = 7 armchair graphene nanoribbons causes drastic changes in its electron and phonon system. By using angle-resolved photoemission spectroscopy of lithium-doped graphene nanoribbons, a quasiparticle band gap renormalization from 2.4 to 2.1 eV is observed. Reaching high doping levels (0.05 electrons per atom), it is found that the effective mass of the conduction band carriers increases to a value equal to the free electron mass. This giant increase in the effective mass by doping is a means to enhance the density of states at the Fermi level which can have palpable impact on the transport and optical properties. Electron doping also reduces the Raman intensity by one order of magnitude, and results in relatively small (4 cm−1) hardening of the G phonon and softening of the D phonon. This suggests the importance of both lattice expansion and dynamic effects. The present work highlights that doping of a semiconducting 1D system is strikingly different from its 2D or 3D counterparts and introduces doped graphene nanoribbons as a new tunable quantum material with high potential for basic research and applications.

D. Haberer*,1, L. Petaccia2, Y. Wang3, H. Quian3, M. Farjam4, S. A. Jafari4,5, H. Sachdev6,7, A. V. Federov8, D. Usachov8, D. V. Vyalikh8,9, X. Liu10, O. Vilkov8,9, V. K. Adamchuk8, S. Irle3, M. Knupfer1, B. Buchner1, and A. Gruneis1,10 1 IFW Dresden, P.O. Box 270116, 01171 Dresden, Germany 2 Elettra Synchrotron Light Laboratory, Sincrotrone Trieste SCpA, S.S. 14 Km 163.5, 34149 Trieste, Italy 3 Department of Chemistry, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan 4 Institute for Research in Fundamental Sciences (IPM), P.O. Box 19395-5531, Tehran, Iran 5 Department of Physics, Sharif University of Technology, Tehran 11155-9161, Iran 6 Anorganische Chemie 8.11, Universitat des Saarlandes, 66041 Saarbrucken, Germany 7 Max-Planck-Institut fur Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany 8 St. Petersburg State University, St. Petersburg 198504, Russia 9 Institut fur Festkorperphysik, TU Dresden, Mommsenstrasse 13, 01069 Dresden, Germany 10 Faculty of Physics, University of Vienna, Strudlhofgasse 4, 1090 Wien, Austria

Carbon nanotubes are archetypical one dimensional systems, with peculiar anisotropic electronic properties. Only recently μm thick films of vertically aligned SWNT became available. The vertical alignment of the nanotube mats allows the realization of scattering geometries promoting specific dipole transitions parallel and normal to the axis of the SWNT. We find well expressed mosaic spreads for the π* and σ* resonances. Full three dimensional modelling of the dipole transitions as well as of the alignment demonstrate polarization dependent X-ray absorption to be an accurate, versatile non destructive and reliable tool to quantify the alignment of SWNT on a bulk scale.

The growth process of inner-shell tubes from C 60 peapods and ferrocene (FeCp 2 ) filled single-wall carbon nanotubes was studied with Raman spectroscopy and X-ray diffraction (XRD). In the peapod case, it is shown that the Raman signal of the fullerenes decays about a factor five faster than the XRD peak of the 1D fullerene chain. The growth of the inner-shell tubes coincides well with the 1D chain decay. In the FeCp 2 case, the inner tubes grow already at 600 °C in about one hour. Additionally, even for the same starting material, the inner-outer tube pair distribution is different than for C 60 based inner tubes.

Defined n-doping of carbon nanotubes can find potential application in nanoelectronics and sensors. An efficient doping can be achieved by substituting Carbon by heteroatoms such as Nitrogen. We explored the formation process of N doped single-walled nanotubes within hot wall chemical vapor deposition employing different (C/N) feedstocks and catalysts. The process was optimized regarding the formation of substitutionally doped SWCNT and double wall CNTs. Analysis of N content and bonding environment is presented.

The synthesis of high quality isotope engineered SWCNT by means of laser ablation and the use of Pt-Rh-Re catalyst mixtures has been established. Optical absorption and Raman spectroscopy as well as transmission electron microscopy are utilized to characterize the obtained SWCNTs with regard to purity and yield. The absence of any ferromagnetic materials, as well as the remarkably low abundance of amorphous carbon renders this material ideal for magnetic studies. The controlled augmentation of 13 C is conveniently confirmed by phonon softening and broadening observed in Raman spectroscopy. Isotope labelling at constant sample quality was achieved in the whole range from 1% 13 C up to 98% 13 C.

Nanotube growth by chemical vapour deposition carbon is carried out for two different catalyst preparation methods: a wet chemistry catalyst is compared to a thin metal film multilayer catalyst. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) micrographs are recorded to investigate the nanotube alignment and the number of walls. Resonance Raman spectroscopy is used for analysis of diameters and the defect concentration.

We investigate the N = 9 atoms wide armchair-type graphene nanoribbons (9-AGNRs) by performing a comprehensive spectroscopic and microscopic characterization of this novel material. In particular, we use X-ray photoelectron, near edge X-ray absorption fine structure, scanning tunneling, polarized Raman and angle-resolved photoemission (ARPES) spectroscopies. The ARPES measurements are aided by calculations of the photoemission matrix elements which yield the position in k space having the strongest photoemission cross section. Comparison with well-studied narrow N = 7 AGNRs shows that the effective electron mass in 9-AGNRs is reduced by two times and the valence band maximum is shifted to lower binding energy by ∼0.6 eV. In polarized Raman measurements of the aligned 9-AGNR, we reveal anisotropic signal depending upon the phonon symmetry. Our results indicate the 9-AGNRs are a novel 1D semiconductor with a high potential in nanoelectronic applications.

Regions of the promoter and exons 5-8 of the tumour suppressor gene p53 were analysed in 25 cases of sporadic bovine leucosis. The study included 17 cases of juvenile leucosis, five cases of adult leucosis and three cases of skin leucosis. Exon 2 of tumour suppressor gene p16 was also investigated in the same samples. No sequence variations were present in the analysed areas of the genes. In p53, this fact represents a clear difference in comparison with enzootic bovine leucosis. In p16, no comparative data are available.