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51.
52.
Impedance characterization at different temperatures has been used to investigate the conductive behavior of Poly(3-hexylthiophene) (P3HT), prepared in different solvents, as the semiconductor layer in organic multilayer capacitor. It has been found that the P3HT films using chloroform and toluene solvents exhibit an enhancement in conductivity by heating following an Arrhenius law with an activation energy transition from 0.004 to 0.026 eV and from 0.002 to 0.015 eV at ~313 K, respectively, which originates from band tail hopping that occurs around the Fermi edge. The boiling point of the used solvents can affect P3HT crystallization process, which causes the difference in conduction and activation energy. 相似文献
53.
Bin Yu 《Journal of Physics and Chemistry of Solids》2010,71(4):468-116
Casein, a natural biopolymer contained in milk, has been successfully intercalated into a Ca-Al-LDH host structure. Synthesis was performed by rehydration of tricalcium aluminate in the presence of casein. The resulting nanohybrids were characterized by powder X-ray diffraction (XRD), elemental analysis, infrared spectroscopy (IR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Further experiments revealed that the single protein strains intercalate instead of the entire casein sub micelles, which are present in milk. Additionally, the pure phospho protein fractions α- and β-casein, which make up ∼80 wt% of total casein were isolated and intercalated into the Ca-Al-LDH host structure, yielding a biopolymer-inorganic hybrid material. 相似文献
54.
P. M. Diesinger D. W. Heermann 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,62(2):209-214
We study the influence of excluded volume interactions
on the behaviour of the mean average crossing number (mACN) for
random off-lattice walks. We investigated Gaussian and equilateral
off-lattice random walks with and without ellipsoidal excluded
volume up to chain lengths of N = 1500 and equilateral random
walks on a cubic lattice up to N = 20000. We find that the
excluded volume interactions have a strong influence on the
behaviour of the local crossing number 〈 a(l1,l2)
〉 at very short distances but only a weak one at large
distances. This behaviour is the basis of the proof
in [ Y. Diao et al., Math. Gen. 36, 11561 (2003); Y. Diao and C. Ernst, Physical and Numerical Models in Knot
Theory Including Applications to the Life Sciences] for the dependence of the mean
average crossing number on the chain length N. We show that the
data is compatible with an Nln(N)-bahaviour for the mACN, even
in the case with excluded volume. 相似文献
55.
K. Broderix M. Weigt A. Zippelius 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(3):441-455
We consider the gelation of particles which are permanently connected by random crosslinks, drawn from an ensemble of finite-dimensional
continuum percolation. To average over the randomness, we apply the replica trick, and interpret the replicated and crosslink-averaged
model as an effective molecular fluid. A Mayer-cluster expansion for moments of the local static density fluctuations is set
up. The simplest non-trivial contribution to this series leads back to mean-field theory. The central quantity of mean-field
theory is the distribution of localization lengths, which we compute for all connectivities. The highly crosslinked gel is
characterized by a one-to-one correspondence of connectivity and localization length. Taking into account higher contributions
in the Mayer-cluster expansion, systematic corrections to mean-field can be included. The sol-gel transition shifts to a higher
number of crosslinks per particle, as more compact structures are favored. The critical behavior of the model remains unchanged
as long as finite truncations of the cluster expansion are considered. To complete the picture, we also discuss various geometrical
properties of the crosslink network, e.g. connectivity correlations, and relate the studied crosslink ensemble to a wider class of ensembles, including the Deam-Edwards
distribution.
Received on 24 April 2002 Published online 14 October 2002
RID="a"
ID="a"deceased
RID="b"
ID="b"e-mail: weigt@theorie.physik.uni-goettingen.de 相似文献
56.
Vollmer A Jurchescu OD Arfaoui I Salzmann I Palstra TT Rudolf P Niemax J Pflaum J Rabe JP Koch N 《The European physical journal. E, Soft matter》2005,17(3):339-343
We use ultraviolet photoelectron spectroscopy to investigate the effect of oxygen and air exposure on the electronic structure of pentacene single crystals and thin films. It is found that O2 and water do not react noticeably with pentacene, whereas singlet oxygen/ozone readily oxidize the organic compound. Also, we obtain no evidence for considerable p-type doping of pentacene by O2 at low pressure. However, oxygen exposure lowers the hole injection barrier at the interface between Au and pentacene by 0.25 eV, presumably due to a modification of the Au surface properties. 相似文献
57.
Welch K Mousavi S Lundberg B Strømme M 《The European physical journal. E, Soft matter》2005,18(1):105-112
A newly developed method for determining the frequency-dependent complex Young's modulus was employed to analyze the mechanical
response of compacted microcrystalline cellulose, sorbitol, ethyl cellulose and starch for frequencies up to 20 kHz. A Debye-like
relaxation was observed in all the studied pharmaceutical excipient materials and a comparison with corresponding dielectric
spectroscopy data was made. The location in frequency of the relaxation peak was shown to correlate to the measured tensile
strength of the tablets, and the relaxation was interpreted as the vibrational response of the interparticle hydrogen and
van der Waals bindings in the tablets. Further, the measured relaxation strength, holding information about the energy loss
involved in the relaxation processes, showed that the weakest material in terms of tensile strength, starch, is the material
among the four tested ones that is able to absorb the most energy within its structure when exposed to external perturbations
inducing vibrations in the studied frequency range. The results indicate that mechanical relaxation analysis performed over
relatively broad frequency ranges should be useful for predicting material properties of importance for the functionality
of a material in applications such as, e.g., drug delivery, drug storage and handling, and also for clarifying the origin of hitherto unexplained molecular processes. 相似文献
58.
Hu X Jiao X Narayanan S Jiang Z K Sinha S Lurio LB Lal J 《The European physical journal. E, Soft matter》2005,17(3):353-359
We have used measurements of the absolute intensity of diffuse X-ray scattering to extract the interfacial tension of a buried polymer/polymer interface. Diffuse scattering was excited by an X-ray standing wave whose phase was adjusted to have a high intensity at the polymer/polymer interface and simultaneously a node at the polymer/air interface. This method permits the capillary-wave-induced roughness of the interface, and hence the interfacial tension, to be measured independently of the polymer/polymer interdiffusion. 相似文献
59.
Mutual mass diffusion and thermal diffusion has been investigated in poly(dimethylsiloxane)/ poly(ethylmethylsiloxane) (PDMS/PEMS) polymer blends of equal weight fractions. Molar masses ranged from below 1 to over 20 kg/mol. Both the mutual mass (D) and the thermal diffusion (DT) coefficient contain a thermally activated factor with an activation temperature of 1415 K. The molar mass dependence of DT is due to an end-group effect of the local friction coefficient. The thermal diffusion coefficient in the limit of long chains and infinite temperature is DT0, = - 1.69×10-7cm2(sK)-1. The Soret coefficient ST of blends far enough away from a critical point is proportional to the static structure factor S(q = 0). 相似文献
60.
Molecular-dynamics results on water confined in a silica pore are reviewed and discussed in connection with experiments performed on water in Vycor and with studies of water in contact with proteins. The properties of confined water are studied as a function of both temperature and hydration level. The interaction of water in the film close to the substrate with the silica atoms induces a strong distortion of the hydrogen bond network. At high hydration levels a double dynamical regime is observed. At low hydration an anomalous diffusion is found upon supercooling with a transition from a Brownian to a non-Brownian regime on approaching the substrate in agreement with results found in studies of water in contact with globular proteins.Received: 1 January 2003, Published online: 14 October 2003PACS:
61.20.-p Structure of liquids - 61.20.Ja Computer simulation of liquid structure 相似文献