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The dynamics of proteins in solution includes a variety of processes, such as backbone and side-chain fluctuations, interdomain motions, as well as global rotational and translational (i.e. center of mass) diffusion. Since protein dynamics is related to protein function and essential transport processes, a detailed mechanistic understanding and monitoring of protein dynamics in solution is highly desirable. The hierarchical character of protein dynamics requires experimental tools addressing a broad range of time- and length scales. We discuss how different techniques contribute to a comprehensive picture of protein dynamics, and focus in particular on results from neutron spectroscopy. We outline the underlying principles and review available instrumentation as well as related analysis frameworks.
We report on the growth and characterization of molecular mixed thin films of α-sexithiophene (6T), a well-known organic p-type semiconductor with high hole mobility, together with its perfluorinated counterpart, the so far rarely studied tetradecafluoro-α-sexithiophene (PF6T). Pure and blended thin films of these two molecules with different mixing ratios were grown on silicon oxide in ultrahigh vacuum by coevaporation. The effect of perfluorination and mixing on crystal structure, morphology, electronic, and optical properties was examined. The evolution of the PF6T crystal structure was followed in situ in real time by X-ray scattering. We found a new thin film structure different from the reported bulk phase with molecules either standing-up or lying-down depending on the growth temperature. The different morphologies of pure films and blends were investigated with atomic force microscopy. The impact of mixing on the core-levels and on the highest occupied molecular orbitals of 6T and PF6T is discussed.
Surface-induced aromatic stabilization (SIAS), a recently proposed mechanism leading to a formation of charge-transfer (CT) states at organic/metal (O/M) interfaces [G. Heimel, et al., Nat. Chem.5, 187 (2013)], was investigated for an aromatic hydrocarbon, diindenoperylene (DIP), by means of synchrotron radiation-based ultraviolet photoelectron spectroscopy (UPS). By employing DIP and noble metal substrates (Ag and Cu), we confirmed the formation of CT states, indicating that an inclusion of a specific functional group with a hetero-atom within adsorbate molecules as suggested before is not necessarily required for the formation of CT states mediated by the SIAS. With a comparison of the mother and analogue molecules, perylene and PTCDA, we discuss the structural requirement for the realization of the SIAS.
We performed temperature-dependent studies on pentacene thin film transistors (TFTs) with and without encapsulation. The capping layer is realized either by a sputtering layer of aluminum oxide (AlOx.) or, alternatively, by a polymeric layer of poly-para-xylylene (PPX). A field-effect can be demonstrated for both capping materials up to temperatures of about 140 – 170 °C, which is about 50 °C above the desorption point of uncapped pentacene thin films on SiO2 substrates. Complementary studies by thermal desorption spectroscopy and temperature dependent x-ray diffraction show that the organic layer remains crystalline on the substrate far above the electrical breakdown temperature of the encapsulated device.
Variation of internal stress states in cold rolled sheet metal can essentially influence the result of forming processes. Therefore it is important to control the forming process by a practicable in line testing method. For this purpose magnetic and ultrasonic nondestructive methods are available. However, it is necessary to calibrate these techniques. This paper describes a first step of such a calibration procedure making use of the neutron diffraction method. On the basis of the diffraction results an assessment of the magnetic and ultrasonic methods for the estimation of residual stress in the cold rolled iron-disks was made. Reasonable measuring concepts for practical applications to forming processes with cold rolled sheet metal are discussed.
The continuously growing and wide-spread utilization of blends of organic electron and hole conducting materials comprises ambipolar field-effect transistors as well as organic photovoltaic cells. Structural, optical and electrical properties are investigated in blends and neat films of the electron donor material Cu-phthalocyanine (CuPc) together with fullerene C60 and Cu-hexadecafluorophthalocyanine (F16CuPc) as electron acceptor materials, respectively. The difference in molecular structure of the spherical C60 and the planar molecule CuPc leads to nanophase separation in the blend, causing charge carrier transport which is limited by the successful formation of percolation paths. In contrast, blends of the similar shaped CuPc and F16CuPc molecules entail mixed crystals, as can be clearly seen by X-ray diffraction measurements. We discuss differences of both systems with respect to their microstructure as well as their electrical transport properties.
Adiponectin is discussed to regulate energy balance and insulin sensitivity. Several studies indicated an association of fasting adiponectin with parameters of the metabolic syndrome. We investigated postprandial adiponectin release and its relation to traits of the metabolic syndrome. Serum adiponectin concentration after an oral glucose tolerance test and after ingestion of a standardised mixed, fat-containing meal in 110 male non-diabetic subjects was assessed. Fasting and postprandial adiponectin and the decrease of adiponectin were correlated with anthropometric and metabolic parameters. Subjects were genotyped for adiponectin − 11 388 G/A promoter single nucleotide polymorphism. Adiponectin slightly decreased after both test meals. A significant decrease was attained 5 and 6 h after the lipid load and 2 h after the glucose load. Particularly, the mixed meal postprandial adiponectin showed stronger correlations with most traits of the metabolic syndrome than fasting adiponectin: postprandial adiponectin with HDL (r 0·30) v. fasting adiponectin with HDL (r 0·23); with postprandial insulin (area under the curve): r − 0·20 v. r − 0·16; with fasting insulin: r 0·10 v. r 0·14; with BMI: r − 0·23 v. r − 0·20; with waist: r − 0·18 v. − 0·16; with systolic blood pressure: r − 0·14 v. r − 0·12; with diastolic blood pressure: r − 0·18 v. r − 0·15. In multivariate analysis, postprandial TAG were the only independent predictor of adiponectin. There was no significant association of adiponectin, NEFA and TAG with − 11 388 G/A adiponectin promoter polymorphism. Our findings favour the interpretation that postprandial adiponectin has the strongest and independent associations to postprandial TAG metabolism.
The PPARγ Pro12Ala polymorphism has been associated in several studies with a decreased risk of obesity, type 2 diabetes and insulin resistance. Weak hints are available about the influence of PPARγ Pro12Ala on postprandial metabolism. In 708 men, aged 45 to 65 years the PPARγ2 Pro12Ala genotypes were determined and postprandial TAG, insulin, glucose and NEFA after a standardized mixed fat meal and insulin and glucose after a glucose load (oral glucose tolerance test; OGTT) were assessed. Using the total sample, we did not find a significant impact of the genotype on the postprandial metabolism. In the subgroup with BMI < 30 kg/m2, fasting and postprandial TAG and insulin levels as well as homeostasis model assessment of insulin resistance (HOMA) were significantly lower in the Ala12Ala group than in the Pro12Pro group after the mixed meal. In contrast, the groups did not differ in insulin levels and HOMA after the OGTT. To investigate if differences between a fat-containing meal and OGTT are caused by adiponectin, we examined a BMI- and age-matched subgroup. No differences were found between the genotypic groups. The effects of the PPARγ2 polymorphism on insulin sensitivity are mediated by affluent dietary fat. We did not find evidence that adiponectin as a fatty-acid-dependent adipocyte factor is a causative factor for this phenomenon.
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