Search results for "SUBSTITUTION"
showing 10 items of 536 documents
[Cr(ddpd) 2 ] 3+ : A Molecular, Water‐Soluble, Highly NIR‐Emissive Ruby Analogue
2015
Bright, long-lived emission from first-row transition-metal complexes is very challenging to achieve. Herein, we present a new strategy relying on the rational tuning of energy levels. With the aid of the large N-Cr-N bite angle of the tridentate ligand ddpd (N,N'-dimethyl-N,N'-dipyridine-2-ylpyridine-2,6-diamine) and its strong σ-donating capabilities, a very large ligand-field splitting could be introduced in the chromium(III) complex [Cr(ddpd)2](3+), that shifts the deactivating and photoreactive (4)T2 state well above the emitting (2)E state. Prevention of back-intersystem crossing from the (2)E to the (4)T2 state enables exceptionally high near-infrared phosphorescence quantum yields a…
Environment- and sequence-dependent modulation of the double-stranded to single-stranded conformational transition of gramicidin A in membranes.
1998
The role of the membrane lipid composition and the individual Trp residues in the conformational rearrangement of gramicidin A along the folding pathway to its channel conformation has been examined in phospholipid bilayers by means of previously described size-exclusion high-performance liquid chromatography HPLC-based strategy (Bano et al. (1991) Biochemistry 30, 886). It has been demonstrated that the chemical composition of the membrane influences the transition rate of the peptide rearrangement from double-stranded dimers to beta-helical monomers. The chemical modification of Trp residues, or its substitution by the more hydrophobic residues phenylalanine or naphthylalanine, stabilized…
On an Inequality for Trigonometric Polynomials In Several Variables
1990
Publisher Summary This chapter presents trigonometric polynomials in n variables. Using the methods of approximation theory, an inequality can be extended to almost periodic functions and to still more general classes of functions as in the case for Bohr's inequality. However, no analogous result exists in the case of two variables. For the solution of problems containing small divisors, the estimate has to be completed by theorems concerning the best approximation of holomorphic functions by trigonometric polynomials in polystrips. The chapter also presents equations to provide an estimate for a differential operator.
Characteristics and Measures for Mobile-Masquerader Detection
2006
Personal mobile devices, as mobile phones, smartphones, and communicators can be easily lost or stolen. Due to the functional abilities of these devices, their use by an unintended person may result in a severe security incident concerning private or corporate data and services. Organizations develop their security policy and mobilize preventive techniques against unauthorized use. Current solutions, however, are still breakable and there still exists strong need for means to detect user substitution when it happens. A crucial issue in designing such means is to define what measures to monitor.
Comparing Tangible and Fully Virtual Haptic Systems for HMI Studies in Simulated Driving Situations
2019
International audience; The contribution of tangible and intangible feedback is compared for virtual tactile car Human-Machine Interfaces (HMI) design, to measure their performance both in static conditions and while driving. A subjectively calibrated transparent glass provides tangible passive haptics, and visual cues are used to study sensory substitution-based intangible interactions. The results show that the performance of the subjects was significantly improved in driving conditions as they interacted faster, more accurately and with a higher satisfaction. In addition, our findings highlight that the contribution of tangible systems is significantly lower in driving conditions, raisin…
Intertemporal Substitution in the Spanish Economy: Evidence from Regional Data*
2018
This paper studies the intertemporal substitution in consumption and leisure for the Spanish economy by estimating the first‐order conditions of an individual optimization model with regional and aggregate data. While first‐order conditions determining intertemporal substitution in consumption show a good econometric fit, and the value we obtain for the intertemporal elasticity of substitution is similar to previously available results, the econometric fit of the intertemporal condition in leisure indicates that the behaviour of the Spanish labour supply over the cycle is more complex than can be explained by the canonical intertemporal choice model.
Optimal Dynamics of Functionality Development in Open Innovation
2009
Abstract Sustainable functionality development has become crucial option for firm's survival in a new paradigm confronting a post-information society. This can be realized by earlier emergence of functionality development. In this context, effective utilization of external innovation resources leads to follower substitution for leader in open innovation. This substitution induces advancements of innovative goods by substituting gratification of their consumption for resistance to them. Thus, optimization of utmost gratification of consumption under certain investment would be crucial for firm strategy. Optimal functionality development dynamics is analyzed in this paper by integrating produ…
Sorting signals in the cytosolic tail of membrane proteins involved in the interaction with plant ARF1 and coatomer.
2004
Summary In mammals and yeast, a cytosolic dilysine motif is critical for endoplasmic reticulum (ER) localization of type I membrane proteins. Retrograde transport of type I membrane proteins containing dilysine motifs at their cytoplasmic carboxy (C)-terminal tail involves the interaction of these motifs with the COPI coat. The C-terminal dilysine motif has also been shown to confer ER localization to type I membrane proteins in plant cells. Using in vitro binding assays, we have analyzed sorting motifs in the cytosolic tail of membrane proteins, which may be involved in the interaction with components of the COPI coat in plant cells. We show that a dilysine motif in the −3,−4 position (rel…
Methyl 4-[5-(4-fluorophenyl)-4-(pyridin-4-yl)-1H-imidazol-2-ylsulfanyl]butanoate
2008
The title compound, C19H18FN3O2S, was synthesized in the course of studies on 2-alkylsufanylimidazoles as p38 mitogen-activated protein kinase inhibitors. The synthesis was achieved by nucleophilic substitution of 4-(4-fluorophenyl)-5-(pyridin-4-yl)-1,3-dihydroimidazole-2-thione with methyl 4-bromobutanoate. The five-membered heterocycle makes dihedral angles of 32.4 (2) and 18.3 (2)° with the fluorophenyl and pyridinyl rings, respectively, indicating a low degree of conjugation between these rings. Intramolecular C—H...N and intermolecular N—H...N hydrogen bonds as well as C—H...π interactions seem to be effective in stabilization of the crystal stru…
Evidence for an Intermediate in the Methylation of CB11H12−with Methyl Triflate: Comparison of Electrophilic Substitution in Cage Boranes and in Aren…
2013
The trideuteriomethylation of BH vertices in CB11H12− and its derivatives with CD3OTf (OTf=triflate, trifluoromethanesulfonate) yields a mixture of BCD3 and BCHD2 substitution products, thus demonstrating the intermediacy of a species with a long enough lifetime for hydrogen scrambling between the boron vertex and the methyl substituent. No such scrambling is observed if CD3OTf is used to methylate toluene. According to density functional theory calculations, the intermediate in BH vertex methylation is a three-center bonded σ adduct of a methyl cation to the BH bond and the proton scrambling occurs via a transition structure containing a distorted square-pyramidal methane attached axially …