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排序方式: 共有85条查询结果,搜索用时 15 毫秒
51.
Block copolymer micelles have been used extensively as carriers for therapeutic drugs and diagnostic molecules. Here, we report the synthesis of nonionic, block copolypeptides, K(P) (x)(rac-L)(y), which have a "reversed" rod-coil structure composed of a hydrophilic, rod-like, α-helical segment attached to a disordered, racemic hydrophobic segment. The self assembly of these block copolypeptides in water was studied, and their compositions were optimized to identify a sample, K(P) (100)(rac-L)(10), which is able to form well defined micelles that are very stable against dilution, high temperatures, and various media. Micelle structure was determined using a combination of electron microscopy and dynamic light scattering measurements. The potential of these micelles as drug delivery carriers was evaluated by encapsulation of the anticancer drug camptothecin. The drug containing micelles were found to be stable. 相似文献
52.
Lee HL Lord SJ Iwanaga S Zhan K Xie H Williams JC Wang H Bowman GR Goley ED Shapiro L Twieg RJ Rao J Moerner WE 《Journal of the American Chemical Society》2010,132(43):15099-15101
Superresolution imaging techniques based on sequential imaging of sparse subsets of single molecules require fluorophores whose emission can be photoactivated or photoswitched. Because typical organic fluorophores can emit significantly more photons than average fluorescent proteins, organic fluorophores have a potential advantage in super-resolution imaging schemes, but targeting to specific cellular proteins must be provided. We report the design and application of HaloTag-based target-specific azido DCDHFs, a class of photoactivatable push-pull fluorogens which produce bright fluorescent labels suitable for single-molecule superresolution imaging in live bacterial and fixed mammalian cells. 相似文献
53.
Eubank JF Wojtas L Hight MR Bousquet T Kravtsov VCh Eddaoudi M 《Journal of the American Chemical Society》2011,133(44):17532-17535
A new pillaring strategy, based on a ligand-to-axial approach that combines the two previous common techniques, axial-to-axial and ligand-to-ligand, and permits design, access, and construction of higher dimensional MOFs, is introduced and validated. Trigonal heterofunctional ligands, in this case isophthalic acid cores functionalized at the 5-position with N-donor (e.g., pyridyl- or triazolyl-type) moieties, are designed and utilized to pillar pretargeted two-dimensional layers (supermolecular building layers, SBLs). These SBLs, based on edge transitive Kagomé and square lattices, are cross-linked into predicted three-dimensional MOFs with tunable large cavities, resulting in isoreticular platforms. 相似文献
54.
We study existence, uniqueness and mass conservation of signed measure valued solutions of a class of stochastic evolution equations with respect to the Wiener sheet, including as particular cases the stochastic versions of the regularized two-dimensional Navier–Stokes equations in vorticity form introduced by Kotelenez. 相似文献
55.
Stochastic McKean-Vlasov equations 总被引:5,自引:0,他引:5
Donald Dawson Jean Vaillancourt 《NoDEA : Nonlinear Differential Equations and Applications》1995,2(2):199-229
We prove the existence and uniqueness of solution to the nonlinear local martingale problems for a large class of infinite systems of interacting diffusions. These systems, which we call the stochastic McKean-Vlasov limits for the approximating finite systems, are described as stochastic evolutions in a space of probability measures onR
d
and are obtained as weak limits of the sequence of empirical measures for the finite systems, which are highly correlated and driven by dependent Brownian motions. Existence is shown to hold under a weak growth condition, while uniqueness is proved using only a weak monotonicity condition on the coefficients. The proof of the latter involves a coupling argument carried out in the context of associated stochastic evolution equations in Hilbert spaces. As a side result, these evolution equations are shown to be positivity preserving. In the case where a dual process exists, uniqueness is proved under continuity of the coefficients alone. Finally, we prove that strong continuity of paths holds with respect to various Sobolev norms, provided the appropriate stronger growth condition is verified. Strong solutions are obtained when a coercivity condition is added on to the growth condition guaranteeing existence.The research has been partially supported by NSERC, Canada. 相似文献
56.
Jarrod Smith Manuel Garcia-Perez K.C. Das 《Journal of Analytical and Applied Pyrolysis》2009,86(1):115-121
The production of bio-oil via the slow pyrolysis of dissolved air flotation (DAF) skimmings from poultry processing is described. The raw DAF skimmings were characterized for physicochemical properties and for thermal behavior (TGA). The bio-oil was produced in a batch pyrolysis system at varying temperatures between 400 and 700 °C to study the effect of temperature on product yield. The fatty acids in the bio-oil produced displayed a high degree of saturation that caused the bio-oil to have poor cold flow properties (high cloud point and viscosity) so a solvent extraction scheme was devised to extract a bio-oil fraction rich in unsaturated fatty acids that could be further esterified into a bio-diesel and fatty nitriles that could be further processed into surfactants. This ethyl acetate-soluble fraction demonstrated much improved cold flow properties as well as lower water content and a higher HHV. The esterification of this soluble fraction was performed using methanol and sulfuric acid as an acid catalyst and the formation of fatty acid methyl esters was verified using GC/MS and FT-IR. 相似文献
57.
Jarrod Vaillancourt Andreas Stintz Mark J. Meisner Xuejun Lu 《Infrared Physics & Technology》2009,52(1):22-24
We report on a low-bias InAs–InGaAs quantum-dot (QD) infrared photodetector (QDIP) with operating temperature of 150 K. Longwave-infrared (LWIR) detection at the peak wavelength of 11.7 μm was achieved. Peak specific photodetectivity D1 of 1.7 × 109 and 9.0 × 107 cm Hz1/2/W were obtained at the operating temperature T of 78 K and 150 K, respectively. A large photoresponsivity of 8.3 A/W and high photoconductive gain of 1100 were demonstrated at a low-bias voltage of V = 0.5 V at T = 150 K. The low-bias and high-temperature performance demonstration based on InAs–GaAs material systems indicates that the QDIP technology is promising for LWIR sensing and imaging. 相似文献
58.
Liu Y Kravtsov VCh Beauchamp DA Eubank JF Eddaoudi M 《Journal of the American Chemical Society》2005,127(20):7266-7267
Single-metal-ion-based rigid molecular building blocks (MBBs) have been utilized to design and synthesize novel metal-organic assemblies. Reaction between In(NO3)3.2H2O and 2,5-pyridinedicarboxylic acid (2,5-H2PDC) has permitted the assembly of two supramolecular isomers, a Kagomé lattice and an unprecedented M6L12 discrete octahedron. 相似文献
59.
A neutral, non-interpenetrated porous metal-organic framework (MOF) having (10,3)-a topology, Cu(3,5-PDC)(DMF)(py), (DMF =N,N'-dimethylformamide, py = pyridine), has been constructed via the assembly of the achiral tri-connected building blocks 3,5-pyridinedicarboxylate (3,5-PDC) and CuN(CO2)2, synthesized in situ. Similarly, a 2D structure having (6,3) topology has been generated, each by means of terminal co-ligand directed synthesis. 相似文献
60.
Galow TH Drechsler U Hanson JA Rotello VM 《Chemical communications (Cambridge, England)》2002,(10):1076-1077
Polymer-mediated self-assembly of functionalized Pd and SiO2 nanoparticles provides highly active hydrogenation and Heck coupling catalysts. 相似文献