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861.
Goede K Grundmann M Holland-Nell K Beck-Sickinger AG 《Langmuir : the ACS journal of surfaces and colloids》2006,22(19):8104-8108
Peptide adhesion on semiconductor surfaces is quantitatively investigated by atomic force microscopy. The selected peptides are shown to cluster at the surface, with the larger, higher, and softer clusters appearing on the surfaces with lower peptide adhesion. Average cluster diameters vary from 40 nm on GaAs (100) to 300 nm on Si (100). Direct adhesion of the peptides to the surface competes with forming molecular aggregates that offer an overall reduced surface contact. 相似文献
862.
Hoffmann M Wanko M Strodel P König PH Frauenheim T Schulten K Thiel W Tajkhorshid E Elstner M 《Journal of the American Chemical Society》2006,128(33):10808-10818
The mechanism of color tuning in the rhodopsin family of proteins has been studied by comparing the optical properties of the light-driven proton pump bacteriorhodopsin (bR) and the light detector sensory rhodopsin II (sRII). Despite a high structural similarity, the maximal absorption is blue-shifted from 568 nm in bR to 497 nm in sRII. The molecular mechanism of this shift is still a matter of debate, and its clarification sheds light onto the general mechanisms of color tuning in retinal proteins. The calculations employ a combined quantum mechanical/molecular mechanical (QM/MM) technique, using a DFT-based method for ground state properties and the semiempirical OM2/MRCI method and ab initio SORCI method for excited state calculations. The high efficiency of the methodology has allowed us to study a wide variety of aspects including dynamical effects. The absorption shift as well as various mutation experiments and vibrational properties have been successfully reproduced. Our results indicate that several sources contribute to the spectral shift between bR and sRII. The main factors are the counterion region at the extracellular side of retinal and the amino acid composition of the binding pocket. Our analysis allows a distinction and identification of the different effects in detail and leads to a clear picture of the mechanism of color tuning, which is in good agreement with available experimental data. 相似文献
863.
Cucos P Pascu M Sessoli R Avarvari N Pointillart F Andruh M 《Inorganic chemistry》2006,45(18):7035-7037
A new diazine tetratopic helicand, H4L, is obtained from 3-formylsalicylic acid and hydrazine. The reaction between H4L and cobalt(II) perchlorate, iron(III) perchlorate, and sodium carbonate leads to triple-stranded tetranuclear anionic helicates, [L3Co(II)2Fe(III)2]2-, which are connected through Na ions, resulting in chiral coordination polymers, [L3Na2Fe2Co2(H2O)4(EtOH)2].3H2O. 相似文献
864.
Inga Cikotiene Rita Buksnaitiene Simonas Rudys Marius Morkunas Dainius Motiejaitis 《Tetrahedron》2010,66(1):251-345
An efficient and versatile tandem processes of acetalisation and cycloisomerization reactions have been developed for the reactions of 6-phenylethynylpyrimidine-5-carbaldehydes. The influence of the catalyst and role of the substituent in the position 4 of the pyrimidine ring have been studied. Regioselective synthesis of 5,7-dihydrofuro[3,4-d]pyrimidine and pyrano[4,3-d]pyrimidine cores is described. 相似文献
865.
866.
This paper investigates positive harmonic functions on domains that are complementary to a subset of a cylindrical surface.
It characterizes, both in terms of harmonic measure and of a Wiener-type criterion, those domains that admit minimal harmonic
functions with exponential growth. Illustrative examples are provided. Two applications are also given. The first of these
concerns minimal harmonic functions associated with an irregular boundary point, and amplifies a recent construction of Gardiner
and Hansen. The second concerns the possible non-approximability of positive harmonic functions by integrable positive harmonic
functions.
This research was supported by Science Foundation Ireland under Grant 06/RFP/MAT057, and is also part of the programme of
the ESF Network “Harmonic and Complex Analysis and Applications” (HCAA). 相似文献
867.
Marius Ghergu 《Journal of Mathematical Analysis and Applications》2009,352(1):132-138
We study the degenerate parabolic equation t∂u=a(δ(x))upΔu−g(u) in Ω×(0,∞), where Ω⊂RN (N?1) is a smooth bounded domain, p?1, δ(x)=dist(x,∂Ω) and a is a continuous nondecreasing function such that a(0)=0. Under some suitable assumptions on a and g we prove the existence and the uniqueness of a classical solution and we study its asymptotic behavior as t→∞. 相似文献
868.
Marian Aprodu Vasile Brînzănescu Marius Marchitan 《Central European Journal of Mathematics》2012,10(4):1321-1330
We survey some parts of the vast literature on vector bundles on Hirzebruch surfaces, focusing on the rank-two case. 相似文献
869.
We present an optofluidic nonlinear coupler fabricated by selective filling of two strands of a photonic crystal fiber with the liquid CCl4 which exhibits a large ultrafast Kerr nonlinearity. We demonstrate power dependent switching in this novel optofluidic device. The large thermo-optical effect of liquids enables us to tune the behavior of the nonlinear coupler by changing the coupling strength with temperature. This opens the road towards flexible designs and realization of a new class of tunable ultrafast nonlinear couplers with switching times below 1 ps. 相似文献
870.
Marius D. R. Lutz Hongyu Zhong Nils Trapp Bill Morandi 《Helvetica chimica acta》2023,106(4):e202200199
We report the synthesis of coordinatively unsaturated cationic rhodium complexes bearing the sterically encumbered electron-rich NHC ligand IPr*OMe. The COD (1,5-cyclooctadiene) complex [Rh(IPr*OMe)(COD)]BF4 adopts a tilted, pseudo-square planar coordination geometry, where bonding to the ipso-carbon of the NHC aryl substituent was observed in the solid state. Hydrogenation of this complex afforded a metastable dihydride complex [Rh(IPr*OMe)(H)2]BF4 with an unusual internal coordination to an arene of the ligand. In the absence of a hydrogen atmosphere, spontaneous reductive elimination of H2 afforded a rhodium complex [Rh(IPr*OMe)]BF4 with a single chelating ligand that stabilizes the highly unsaturated metal by two-fold π-face donation as suggested by NMR spectroscopy and computational studies. This unusual complex might serve as a versatile precatalyst for a variety of transformations. 相似文献