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71.
Levi MD Fisyuk AS Demadrille R Markevich E Gofer Y Aurbach D Pron A 《Chemical communications (Cambridge, England)》2006,(31):3299-3301
Incorporation of electron accepting units (oxadiazole) into the 2,5-thienylene conjugated chain leads to a significant improvement in the n-doping-undoping redox stability of the resulting polymer. 相似文献
72.
Yossi Zafrani 《Tetrahedron》2009,65(27):5278-5283
A convenient method for the difluoromethylation of phenols and thiophenols, using diethyl bromodifluoromethylphosphonate (1) as a difluorocarbene precursor, is described. This commercially available phosphonate was found to undergo an extremely facile P-C bond cleavage on basic hydrolysis (−78 °C to rt), presumably leading to the bromodifluoromethyl anion, which subsequently converts to a difluorocarbene intermediate. The latter is trapped by phenolates 2 or thiophenolates 3 to give the corresponding difluoromethyl ethers and thioethers in good to excellent yield. The resulting eco-friendly side product, diethyl phosphate ion, is easily separated from the reaction mixture due to its excellent solubility in water. Due to the mild conditions applied to this reaction, phenolate ions bearing carbonyl or enolate functions are selectively difluoromethylated. 相似文献
73.
74.
Molotskii M Agronin A Urenski P Shvebelman M Rosenman G Rosenwaks Y 《Physical review letters》2003,90(10):107601
We observe a stringlike domain penetration from a ferroelectric surface deep into the crystal bulk induced by a high voltage atomic force microscope tip. The domains, which resemble channels of an electrical breakdown, nucleate under an electric field of around 10(7) V/cm at the ferroelectric surface, and grow throughout the crystal bulk where the external electric field is practically zero. A theory explaining the shape of the formed domains is presented. It shows that the driving force for the domain breakdown is the decrease of the total free energy of the system with increasing domain length. 相似文献
75.
We present a fast algorithm for solving m X n systems of linear equations Ax = c with at most two variables per equation. The algorithm makes use of a linear-time algorithm for constructing a spanning forest of an undirected graph, and it requires 5m + 2n – 2 arithmetic operations in the worst case. 相似文献
76.
Three different methods for the amplified detection of a single-base mismatch in DNA are described using microgravimetric quartz-crystal-microbalance as transduction means. All methods involve the primary incorporation of a biotinylated base complementary to the mutation site in the analyzed double-stranded primer/DNA assembly. The double-stranded assembly is formed between 25 complementary bases of the probe DNA assembled on the Au-quartz crystal and the target DNA. One method of amplification includes the association of avidin- and biotin-labeled liposomes to the sensing interface. The second method of amplified detection of the base mismatch includes the association of an Au-nanoparticle-avidin conjugate to the sensing interface, and the secondary Au-nanoparticle-catalyzed deposition of gold on the particles. The third amplification route includes the binding of the avidin-alkaline phosphatase biocatalytic conjugate to the double-stranded surface followed by the oxidative hydrolysis of 5-bromo-4-chloro-3-indolyl phosphate to the insoluble product indigo derivative that precipitates on the transducer. Comparison of the three amplification routes reveals that the catalytic deposition of gold on the Au-nanoparticle/avidin conjugate is the most sensitive method, and the single-base mismatch in the analyzed DNA is detected with a sensitivity that corresponds to 3x10(-16) M. 相似文献
77.
Weizmann Y Elnathan R Lioubashevski O Willner I 《Journal of the American Chemical Society》2005,127(36):12666-12672
The endonuclease scission of magnetic particles functionalized with sequence-specific DNAs, which are associated on cantilevers, is followed by the magnetic force-amplified readout of the reactions by the nano-mechanical deflection/retraction of the cantilevers. The systems are employed to develop AND or OR logic gates and to detect single base mismatch specificity of the endonucleases. The two endonucleases EcoRI (E(A)) and AscI (E(B)) are used as inputs. The removal of magnetic particles linked to the cantilever by the duplexes 1/1a and 2/2a via the simultaneous cleavage of the DNAs by E(A) and E(B) leads to the retraction of the magnetically deflected cantilever and to the establishment of the "AND" gate. The removal of the magnetic particles linked to the cantilevers by the duplex 3/3a by either E(A) or E(B) leads to the retraction of the magnetically deflected cantilever and to the establishment of the "OR" gate. The magnetic force-amplified readout of endonuclease activities is also employed to reveal single base mismatch specificity of the biocatalysts. 相似文献
78.
Cohen B Huppert D Solntsev KM Tsfadia Y Nachliel E Gutman M 《Journal of the American Chemical Society》2002,124(25):7539-7547
The aqueous phase of water/AOT reversed micelles having varying diameters was probed by a single free diffusing proton that was released form a hydrophilic photoacid molecule (2-naphthol-6,8-disulfonate). The fluorescence decay signals were reconstructed through the geminate recombination algorithm, accounting for the reversible nature of the proton-transfer reactions at the surface of the excited molecule and at the water/detergent interface. The radial diffusion of the proton inside the aqueous phase was calculated accounting for both the entropy of dilution and the total electrostatic energy of the ion pair, consisting of the pair-energy and self-energy of the ions. The analysis implied that micellar surface must be modeled with atomic resolution, assuming that the sulfono residue protrudes above the water/hydrocarbon interface by approximately 2 A. The analysis of the fluorescence decay curves implies that the molecule is located in a solvent with physical-chemical properties very similar to bulk water, except for the dielectric constant. For reversed micelles with r(max) > or = 16 A, the dielectric constant of the aqueous phase was approximately 70 and for smaller micelles, where approximately 60% of the water molecule is in contact with the van der Waals surface of the micelle, it is as low as 60. This reduction is a reflection of the increased fraction of water molecule that is in close interaction with the micelle surface. 相似文献
79.
Weizmann Y Braunschweig AB Wilner OI Cheglakov Z Willner I 《Chemical communications (Cambridge, England)》2008,(40):4888-4890
Alpha and beta conjugated bis-aptamers against thrombin act as bidentate "glue" for the self-assembly of thrombin nanowires; mixing the bidentate aptamer with a tripodal tridentate alpha aptamer construct yields branched thrombin nanowire structures. 相似文献
80.
Spontaneous instabilities of nanoparticles are known to be influenced by the temperature, and strongly depend on the particle
size. However, it is not clear what is the role of the surrounding material that is in contact with the particle. Here we
report on the difference between spontaneous rotations of Bi nanoparticles embedded in amorphous SiO and those embedded in
liquid Ga. The phenomenon was studied quantitatively by time resolved transmission electron microscopy using Fourier Transform
analysis of highresolution electron microscopy images. While rotations of Bi nanoparticles embedded in amorphous SiO occur
by all angles, the rotations of Bi nanoparticles embedded in liquid Ga occur by discrete angles. Our results point quantitatively,
for the first time, to the role and importance of the contacting surrounding surface during the rotation of nanoparticles. 相似文献