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121.
Carolina Toloza Porras Dagmar R. D'hooge Paul H. M. Van Steenberge Marie‐Françoise Reyniers Guy B. Marin 《大分子反应工程》2013,7(7):311-326
Kinetic Monte Carlo simulations are performed to investigate the capability of ICAR ATRP for the synthesis of well‐defined poly(isobornyl acrylate‐b‐styrene) block(‐like) copolymers using one‐pot semi‐batch and two‐pot batch procedures. The block copolymer quality is quantified via a block deviation (〈BD〉) value. For 〈BD〉 values lower than 0.30, the quality is defined as good and for well‐chosen polymerization conditions the formation of homopolymer chains upon addition of the second monomer can be suppressed. A better block quality is obtained when isobornyl acrylate is polymerized first. For lower Cu levels a one‐pot semi‐batch procedure allows a much faster ATRP and better control over the polymer properties than a two‐pot batch procedure.
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The influence of an asymmetric periodic grooved cell surface on the 2D static director configuration of a nematic liquid crystal has been investigated. The minimum in the Frank-Oseen free energy was solved numerically with the Rapini-Papoular form of the surface anchoring energy at the nematic-grating interface. Results are presented for the variation of pretilt angle in the tilted bulk director field as a function of the surface groove depth, pitch and asymmetry and the bulk parameters. The simulations demonstrate the existence of two energetically degenerate high and low pretilted bulk alignment configurations. The pretilt values in these two regimes and also for the low tilt regime with finite surface anchoring are consistent with experimental results. An effective increase in the resolution of the model is obtained by using an irregular grid to describe the surface profile. 相似文献
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Dr. Fu Chen Dr. Guibin Ma Dr. Guy M. Bernard Prof. Roderick E. Wasylishen Prof. Ronald G. Cavell Dr. Robert McDonald Dr. Michael J. Ferguson 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(8):2826-2838
Several 1:1 adducts of gallium trihalides with triarylphosphines, X3Ga(PR3) (X=Cl, Br, and I; PR3=triarylphosphine ligand), were investigated by using solid‐state 69/71Ga and 31P NMR spectroscopy at different magnetic‐field strengths. The 69/71Ga nuclear quadrupolar coupling parameters, as well as the gallium and phosphorus magnetic shielding tensors, were determined. The magnitude of the 71Ga quadrupolar coupling constants (CQ(71Ga)) range from approximately 0.9 to 11.0 MHz . The spans of the gallium magnetic shielding tensors for these complexes, δ11?δ33, range from approximately 30 to 380 ppm; those determined for phosphorus range from 10 to 40 ppm. For any given phosphine ligand, the gallium nuclei are most shielded for X=I and least shielded for X=Cl, a trend previously observed for InIII–phosphine complexes. This experimental trend, attributed to spin‐orbit effects of the halogen ligands, is reproduced by DFT calculations. The signs of CQ(69/71Ga) for some of the adducts were determined from the analysis of the 31P NMR spectra acquired with magic angle spinning (MAS). The 1J(69/71Ga,31P) and ΔJ(69/71Ga, 31P) values, as well as their signs, were also determined; values of 1J(71Ga,31P) range from approximately 380 to 1590 Hz. Values of 1J(69/71Ga,31P) and ΔJ(69/71Ga,31P) calculated by using DFT have comparable magnitudes and generally reproduce experimental trends. Both the Fermi‐contact and spin‐dipolar Fermi‐contact mechanisms make important contributions to the 1J(69/71Ga,31P) tensors. The 31P NMR spectra of several adducts in solution, obtained as a function of temperature, are contrasted with those obtained in the solid state. Finally, to complement the analysis of NMR spectra for these adducts, single‐crystal X‐ray diffraction data for Br3Ga[P(p‐Anis)3] and I3Ga[P(p‐Anis)3] were obtained. 相似文献
127.
Dr. Daniel G. Silva Pim-Bart Feijens Rik Hendrickx An Matheeussen Lucie Grey Prof. Dr. Guy Caljon Prof. Dr. Louis Maes Prof. Dr. Flavio S. Emery Dr. Anna Junker 《ChemistryOpen》2021,10(9):922-927
This study identified the isoindolone ring as a scaffold for novel agents against Trypanosoma brucei rhodesiense and explored the structure-activity relationships of various aromatic ring substitutions. The compounds were evaluated in an integrated in vitro screen. Eight compounds exhibited selective activity against T. b. rhodesiense (IC50<2.2 μm ) with no detectable side activity against T. cruzi and Leishmania infantum. Compound 20 showed low nanomolar potency against T. b. rhodesiense (IC50=40 nm ) and no toxicity against MRC-5 and PMM cell lines and may be regarded as a new lead template for agents against T. b. rhodesiense. The isoindolone-based compounds have the potential to progress into lead optimization in view of their highly selective in vitro potency, absence of cytotoxicity and acceptable metabolic stability. However, the solubility of the compounds represents a limiting factor that should be addressed to improve the physicochemical properties that are required to proceed further in the development of in vivo-active derivatives. 相似文献
128.
Kirill Arapov Kaarle Jaakkola Vladimir Ermolov Guy Bex Eric Rubingh Samiul Haque Henrik Sandberg Robert Abbel Gijsbertus de With Heiner Friedrich 《固体物理学:研究快报》2016,10(11):812-818
Despite the great promise of printed flexible electronics from 2D crystals, and especially graphene, few scalable applications have been reported so far that can be termed roll‐to‐roll compatible. Here we combine screen printed graphene with photonic annealing to realize radio‐frequency identification devices with a reading range of up to 4 meters. Most notably our approach leads to fatigue resistant devices showing less than 1% deterioration of electrical properties after 1000 bending cycles. The bending fatigue resistance demonstrated on a variety of technologically relevant plastic and paper substrates renders the material highly suitable for various printable wearable devices, where repeatable dynamic bending stress is expected during usage. All applied printing and post‐processing methods are compatible with roll‐to‐roll manufacturing and temperature sensitive flexible substrates providing a platform for the scalable manufacturing of mechanically stable and environmentally friendly graphene printed electronics.
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We present a low-temperature scanning tunneling microscopy study of the alpha-Sn/Si(111) surface that demonstrates the fluctuating behavior of the Sn adatoms. The dynamical fluctuation model, successfully applied in describing the alpha-Sn/Ge(111) surface, is proposed for the related alpha-Sn/Si(111) surface too, although with a much lower transition temperature. In addition, a new phenomenon appears responsible for the unexpected evidence that the average oscillation frequency remains constant at temperatures lower than 15 K, in contradiction to the Arrhenius law. We explain this phenomenon as quantum tunneling of Sn adatoms. 相似文献
130.
Wise RG Lujan BJ Schweinhardt P Peskett GD Rogers R Tracey I 《Magnetic resonance imaging》2007,25(6):801-810
BACKGROUND AND PURPOSE: Functional neuroimaging can distinguish components of the pain experience associated with anticipation to pain from those associated with the experience of pain itself. Anticipation to pain is thought to increase the suffering of chronic pain patients. Inappropriate anxiety, of which anticipation is a component, is also a cause of disability. We present a pharmacological functional magnetic resonance imaging (fMRI) study in which we investigate the selective modulation by midazolam of brain activity associated with anticipation to pain compared to pain itself. METHODS: Eight right-handed male volunteers underwent fMRI combined with a thermal pain conditioning paradigm and midazolam (30 mug/kg) or saline administration on different occasions, with order randomized across volunteers. Volunteers learned to associate a colored light with either painful, hot stimulation or nonpainful, warm stimulation to the back of the left hand. RESULTS: Comparison of the period during thermal stimulation (pain-warm) revealed a network of brain activity commonly associated with noxious stimulation, including activities in the anterior cingulate cortex (ACC), the bilateral insular cortices (anterior and posterior), the thalamus, S1, the motor cortex, the brainstem, the prefrontal cortex and the cerebellum. Comparison of the periods preceding thermal stimulation (anticipation to pain-anticipation to warm) revealed activity principally in the ACC, the contralateral anterior insular cortex and the ipsilateral S2/posterior insula. Detected by a region-of-interest analysis, midazolam reduced the activity associated specifically with anticipation to pain while controlling for anticipation to warm. This was most significant in the contralateral anterior insula (P<.05). There were no significant drug effects on the activity associated with pain itself. CONCLUSION: In identifying a pharmacological effect on activity preceding but not during pain, we have successfully demonstrated an fMRI assay that can be used to study the action of anxiolytic agents in a relatively small cohort of humans. 相似文献