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151.
F. Bloisi A. Pezzella M. Barra M. Alfè F. Chiarella A. Cassinese L. Vicari 《Applied Physics A: Materials Science & Processing》2011,105(3):619-627
Eumelanin is an important pigment almost ubiquitous in animals and plants exhibiting interesting charge transport capabilities.
Its poor solubility in common solvents represents a severe limitation for preparing thin films. It was recently demonstrated
that eumelanin films can be successfully deposited with the MAPLE (Matrix Assisted Pulsed Laser Evaporation) technique starting
from a frozen water suspension, using infrared laser radiation. The low laser absorption of ice together with the high absorption
of eumelanin suggests that the target ablation is due to laser energy absorbed by the eumelanin molecules, followed by thermal
energy transfer, and ejection of ice/water/vapor containing undamaged eumelanin molecules and supramolecular structures. 相似文献
152.
Melanie Aubert Ronan C. Nicolas Weronika Pawelec Carl‐Eric Wilén Michael Roth Rudolf Pfaendner 《先进技术聚合物》2011,22(11):1529-1538
A number of symmetrical and unsymmetrical azoalkanes of the general formula R′?N = N?R and related azoxy, hydrazone as well as azine derivatives have been synthesized in order to assess their potential as novel flame retardants for polypropylene alone or in combination with commercially available flame retardants such as alumina trihydrate (ATH), decabromodiphenyl ether (DecaBDE) and tris(3‐bromo‐2,2‐bis(bromomethyl)‐propyl)phosphate (TBBPP). The experimental results show that in the series of different sized azocycloalkanes the flame retardant efficacy decreased in the following order: R = cyclohexyl > cyclopentyl > cyclobutyl > cyclooctanyl >> cyclododecanyl. Whereas in the series of aliphatic azoalkanes compounds the efficacy decreased in the following order: R = n‐alkyl > tert‐butyl > tert‐octyl. In addition, also some of the prepared azoxy, azine, and hydrazone derivatives provide flame retardancy to polypropylene films at already very low concentrations (0.25–1 wt%). Noteworthy is that in contrast to other halogen‐free radical generators, the azoalkanes are also very effective as flame retardants in polypropylene thick moldings. Interestingly, it was found that 4,4′‐bis(cyclohexylazocyclohexyl)‐methane) shows a strong synergistic effect with ATH. Thus, in the presence of 0.5 wt% of azoalkane the ATH loading could be reduced from 60 to 25 wt% and still UL94 V‐2 rating could be reached. Furthermore, the fire testing data reveal that azoalkanes show a synergistic effect with DecaBDE and when used in conjunction with very low loadings of TBBPP. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
153.
Background
Microbial degradation of azo dyes is commonly initiated by the reduction of the azo bond(s) by a group of NADH or NADPH dependant azoreductases with many requiring flavin as a cofactor. In this study, we report the identification of a novel flavin-free NADPH preferred azoreductase encoded by azoB in Pigmentiphaga kullae K24. 相似文献154.
Functionalization of Pyrene To Prepare Luminescent Materials—Typical Examples of Synthetic Methodology
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Dr. Xing Feng Dr. Jian‐Yong Hu Prof. Dr. Carl Redshaw Prof. Dr. Takehiko Yamato 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(34):11898-11916
Pyrene‐based π‐conjugated materials are considered to be an ideal organic electro‐luminescence material for application in semiconductor devices, such as organic light‐emitting diodes (OLEDs), organic field‐effect transistors (OFETs) and organic photovoltaics (OPVs), and so forth. However, the great drawback of employing pyrene as an organic luminescence material is the formation of excimer emission, which quenches the efficiency at high concentration or in the solid‐state. Thus, in order to obtain highly efficient optical devices, scientists have devoted much effort to tuning the structure of pyrene derivatives in order to realize exploitable properties by employing two strategies, 1) introducing a variety of moieties at the pyrene core, and 2) exploring effective and convenient synthetic strategies to functionalize the pyrene core. Over the past decades, our group has mainly focused on synthetic methodologies for functionalization of the pyrene core; we have found that formylation/acetylation or bromination of pyrene can selectly lead to functionalization at K‐region by Lewis acid catalysis. Herein, this Minireview highlights the direct synthetic approaches (such as formylation, bromination, oxidation, and de‐tert‐butylation reactions, etc.) to functionalize the pyrene in order to advance research on luminescent materials for organic electronic applications. Further, this article demonstrates that the future direction of pyrene chemistry is asymmetric functionalization of pyrene for organic semiconductor applications and highlights some of the classical asymmetric pyrenes, as well as the latest breakthroughs. In addition, the photophysical properties of pyrene‐based molecules are briefly reviewed. To give a current overview of the development of pyrene chemistry, the review selectively covers some of the latest reports and concepts from the period covering late 2011 to the present day. 相似文献
155.
Carl A. Batt Anna M. Waldron Natalie Broadwater 《Journal of nanoparticle research》2008,10(7):1141-1148
Nanotechnology will be an increasing part of the everyday lives of most people in the world. There is a general recognition
that few people understand the implications of the technology, the technology itself or even the definition of the word. This
lack of understanding stems from a lack of knowledge about science in general but more specifically difficulty in grasping
the size scale and symbolism of nanotechnology. A potential key to informing the general public is establishing the ability
to comprehend the scale of nanotechnology. Transitioning from the macro to the nanoscale seems to require an ability to comprehend
scales of one-billion. Scaling is a skill not common in most individuals and tests of their ability to extrapolate size based
upon scaling a common object demonstrates that most individuals cannot scale to the extent needed to make the transition to
nanoscale. Symbolism is another important vehicle to providing the general public with a basis to understand the concepts
of nanotechnology. With increasing age, individuals are able to draw representations of atomic scale objects, but these tend
to be iconic and the different representations not easily translated. Ball and stick models are most recognized by the public,
which provides an opportunity to present not only useful symbolism but also a reference point for the atomic scale. 相似文献
156.
A controlled interference is proposed to reduce, by two orders of magnitude, the decoherence of a quantum gate for which the gate fidelity is limited by coupling to states other than the /0> and /1> qubit states. This phenomenon is demonstrated in an ultracold neutral atom implementation of a phase gate using qubits based on motional states in individual wells of an optical lattice. 相似文献
157.
158.
We give necessary and sufficient conditions for the convergence of cardinal interpolation with bivariate box splines as the degree tends to infinity. 相似文献
159.
Kenneth B. Tomer Tarekegn Gebreyesus Carl Djerassi 《Journal of mass spectrometry : JMS》1973,7(4):383-393
The mass spectra of C13 labeled o- nitrobenzoic acid and o-nitrobenzaldehyde were studied. Earlier proposed fragmentations involving group migration to a charge-carrying vacant ortho position were verified. A completely unexpected interaction in o- nitroanisole was uncovered by O18labeling. 相似文献
160.
Carl Budtz-Jørgensen Peter T. Guenther Alan B. Smith James F. Whalen 《Zeitschrift für Physik A Hadrons and Nuclei》1982,306(3):265-272
Neutron total cross sections of58Ni were measured at 25 keV intervals from 0.9 to 4.5 MeV with 50–100 keV resolutions. Attention was given to self-shielding corrections to the observed total cross sections. Differential elastic- and inelastic-scattering cross sections were measured at 50 keV intervals from 1.35 to 4.0 MeV with 50–100 keV resolutions. Inelastic excitation of levels at 1.458±0.009, 2.462+-0.010, 2.791±0.015, 2.927+-0.012 and 3.059+-0.025 MeV was observed. The experimental results were interpreted in terms of optical-statistical and coupled-channels models. 相似文献