排序方式: 共有23条查询结果,搜索用时 15 毫秒
1.
Zhang X Sieval AB Hummelen JC Hessen B 《Chemical communications (Cambridge, England)》2005,(12):1616-1618
Polyethene with fullerene moieties pendant on short-chain branches was prepared by the catalytic copolymerization of ethene and a fullerene-containing vinylic comonomer, yielding polyethene copolymers containing up to 25 wt% of C60. 相似文献
2.
In the present study, we demonstrate the benefits of a shear-driven rotating microchamber system for the enhancement of microarray hybridizations, by comparing the system with two commonly used hybridization techniques: purely diffusion-driven hybridization under coverslip and hybridization using a fully automated hybridization station, in which the sample is pumped in an oscillating manner. Starting from the same amount of DNA for the three different methods, a series of hybridization experiments using mouse lung and testis DNA is presented to demonstrate these benefits. The gain observed using the rotating microchamber is large: both in terms of analysis speed (up to tenfold increase) and in final spot intensity (up to sixfold increase). The gain is due to the combined effect of the hybridization chamber miniaturization (leading to a sample concentration increase if comparing iso-mass conditions) and the transport enhancement originating from the rotational shear-driven flow induced by the rotation of the chamber bottom wall. 相似文献
3.
Markov DE Amsterdam E Blom PW Sieval AB Hummelen JC 《The journal of physical chemistry. A》2005,109(24):5266-5274
Exciton diffusion and photoluminescence quenching in conjugated polymer/fullerene heterostructures are studied by time-resolved photoluminescence. It is observed that heterostructures consisting of a spin-coated poly(p-phenylene vinylene) (PPV)-based derivative and evaporated C60 are ill-defined because of diffusion of C60 into the polymer, leading to an overestimation of the exciton diffusion length. This artifact is resolved by the use of a novel, thermally side-chain polymerizing and cross-linking fullerene derivative (F2D) containing two diacetylene moieties, forming a completely immobilized electron acceptor layer. With this heterostructure test system, an exciton diffusion length of 5 +/- 1 nm is derived for this PPV derivative from time-integrated luminescence quenching data. 相似文献
4.
Rispens MT Meetsma A Rittberger R Brabec CJ Sariciftci NS Hummelen JC 《Chemical communications (Cambridge, England)》2003,(17):2116-2118
Two crystal structures of PCBM, obtained from different crystallisation solvents, are presented; a proposed link with solvent dependence of the efficiency of MDMO-PPV:PCBM solar cells is described. 相似文献
5.
Fracasso D Valkenier H Hummelen JC Solomon GC Chiechi RC 《Journal of the American Chemical Society》2011,133(24):9556-9563
This paper compares the current density (J) versus applied bias (V) of self-assembled monolayers (SAMs) of three different ethynylthiophenol-functionalized anthracene derivatives of approximately the same thickness with linear-conjugation (AC), cross-conjugation (AQ), and broken-conjugation (AH) using liquid eutectic Ga-In (EGaIn) supporting a native skin (~1 nm thick) of Ga(2)O(3) as a nondamaging, conformal top-contact. This skin imparts non-Newtonian rheological properties that distinguish EGaIn from other top-contacts; however, it may also have limited the maximum values of J observed for AC. The measured values of J for AH and AQ are not significantly different (J ≈ 10(-1)A/cm(2) at V = 0.4 V). For AC, however, J is 1 (using log averages) or 2 (using Gaussian fits) orders of magnitude higher than for AH and AQ. These values are in good qualitative agreement with gDFTB calculations on single AC, AQ, and AH molecules chemisorbed between Au contacts that predict currents, I, that are 2 orders of magnitude higher for AC than for AH at 0 < |V| < 0.4 V. The calculations predict a higher value of I for AQ than for AH; however, the magnitude is highly dependent on the position of the Fermi energy, which cannot be calculated precisely. In this sense, the theoretical predictions and experimental conclusions agree that linearly conjugated AC is significantly more conductive than either cross-conjugated AQ or broken conjugate AH and that AQ and AH cannot necessarily be easily differentiated from each other. These observations are ascribed to quantum interference effects. The agreement between the theoretical predictions on single molecules and the measurements on SAMs suggest that molecule-molecule interactions do not play a significant role in the transport properties of AC, AQ, and AH. 相似文献
6.
Weckx S Carlon E DeVuyst L Van Hummelen P 《The journal of physical chemistry. B》2007,111(48):13583-13590
While designing oligonucleotide-based microarrays, cross-hybridization between surface-bound oligos and non-intended labeled targets is probably the most difficult parameter to predict. Although literature describes rules-of-thumb concerning oligo length, overall similarity, and continuous stretches, the final behavior is difficult to predict. The aim of this study was to investigate the effect of well-defined mismatches on hybridization specificity using CodeLink Activated Slides and to study quantitatively the relation between hybridization intensity and Gibbs free energy (DeltaG), taking the mismatches into account. Our data clearly showed a correlation between the hybridization intensity and DeltaG of the oligos over 3 orders of magnitude for the hybridization intensity, which could be described by the Langmuir model. As DeltaG was calculated according to the nearest-neighbor model, using values related to DNA hybridizations in solution, this study clearly shows that target-probe hybridizations on microarrays with a three-dimensional coating are in quantitative agreement with the corresponding reaction in solution. These results can be interesting for some practical applications. The correlation between intensity and DeltaG can be used in quality control of microarray hybridizations by designing probes and corresponding RNA spikes with a range of DeltaG values. Furthermore, this correlation might be of use to fine-tune oligonucleotide design algorithms in a way to improve the prediction of the influence of mismatching targets on microarray hybridizations. 相似文献
7.
8.
9.
Pichler T. Knupfer M. Golden M.S. Fink J. Winter J. Haluska M. Kuzmany H. Keshavarz-K M. Bellavia-Lund C. Sastre A. Hummelen J.C. Wudl F. 《Applied Physics A: Materials Science & Processing》1997,64(3):301-305
\chem{Rb_1C_{60}} and dimerised using electron energy-loss spectroscopy in transmission. From the excitation spectra a reduced density of states is observed for polymerized . This is in contrast to and can be explained by the different type of \squt{doping} and by the different bonding between the fullerene molecules
in the two systems.
Additional information about the optical properties was obtained from the low energy loss function. Using a Kramers-Kronig
analysis, the dielectric function, (), and the optical conductivity, (), have been derived. and the onset of the spectral weight have been compared between the polymer, the dimer and . This onset of spectral weight is found to be at and for o- and for , respectively.
Received: 28 October 1996/Accepted: 13 December 1996 相似文献
10.
S. Haffner T. Pichler M. Knupfer B. Umlauf R. Friedlein M.S. Golden J. Fink M. Keshavarz-K. C. Bellavia-Lund A. Sastre J.C. Hummelen F. Wudl 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,1(1):11-17
We report the results of a detailed study of the occupied and unoccupied electronic structure of dimers of the new heterofullerene
by means of photoemission and electron energy-loss spectroscopy. A close similarity is found between the electronic structures
of pristine and with an additional broadening of the spectra in the former due to the distortion of the fullerene cage caused both by dimerization
and the chemical substitution. Both the occupied and unoccupied electronic states, as well as the interband transitions between
them, attest to the high degree of molecular character retained in the solid state. Comparison of the shake-up structures
in the and X-ray photoemission spectra confirm that the highest lying occupied states in the heterofullerene have a strong degree of
N character, whereas the lowest lying unoccupied states have mainly C character. We also present the optical conductivity
of the heterofullerene (derived from the loss function), which shows an optical gap of 1.4 eV, some 0.4 eV smaller than that
of .
Received: 25 August 1997 / Revised: 22 September 1997 / Accepted: 16 October 1997 相似文献