In this paper a fiber optic surface plasmon resonance (FO-SPR) sensor was used to analyze the melting process of DNA linked to silica nanoparticles. Real-time monitoring of a DNA melting process has rarely been studied using surface plasmon resonance (SPR), since most commercial SPR setups do not allow for dynamic and accurate temperature control above 50 °C. The FO-SPR sensor platform, with silica nanobead signal amplification, allows sensing inside a standard PCR thermocycler, which makes high resolution DNA melting curve analysis possible. This innovative combination was used to characterize the hybridization and melting events between DNA immobilized on the sensor surface and DNA probes on silica nanoparticles. At optimized hybridization conditions complementary DNA strands of different lengths could be distinguished. While the real-time FO-SPR analysis of DNA hybridization did not result in significant variances, the analysis of DNA melting determined the exact length of overlap and the matching Gibbs energy. 相似文献
Around the globe governments, businesses and citizens are actively involved in voluntary programmes that seek an improved uptake of retrofits of the existing building stock. A fuzzy set qualitative comparative analysis (fsQCA) is used to understand the opportunities, performance and constraints of such programmes. Building on a series of 20 voluntary programmes in Australia, the Netherlands and the United States (including a series of 101 original interviews), the analysis finds that the majority of these have not succeeded in incentivizing their participants to take meaningful action. Insights are presented into why the majority of these programmes have underperformed, and what binds together the small number of programmes that have achieved positive results. 相似文献
Fabric formwork entails the use of fabrics as the main contact material for a concrete mould. The fabric is either hung or prestressed in a supporting falsework frame. Beams or trusses cast in fabric formwork are inherently non‐prismatic and have been shown to offer potential for structurally efficient shapes. The casting of beams or trusses in fabric formwork is a highly non‐linear problem due to the interaction of the fluid concrete with the woven, prestressed fabric material. Numerical models need to be developed for the engineering of these elements. To this end, it is demonstrated that it is feasible to integrate manufacturing constraints in an automatic optimization process. This is achieved by creating an automated computational framework that includes fabric form‐finding and finite element analysis, which operate within an optimization process that uses principles from biological evolution. The results show structurally efficient and manufacturable beams and demonstrate potential for optimization in general that explicitly includes fabrication considerations. 相似文献
Biohybrid amphiphiles composed of a protein head group and a hydrophobic polymer tail self‐assemble in water in a similar way as low molecular weight surfactants. Owing to the presence of the protein, biohybrid amphiphiles, and their assemblies, however, hold the additional feature of a built‐in (bio)functionality. These compounds therefore are promising building blocks for the synthesis of functional nanometer‐sized materials. We discuss recent advances in the relatively young field of protein–polymer hybrid amphiphiles, which so far mainly involved exploratory and fundamental studies providing a conceptual basis for the development of more complex systems with interesting applications in the future.
The hydrodynamics of bubble columns with concentrated slurries of paraffin oil (density, ρL = 790 kg/m3; viscosity, μL = 0.0029 Pa·s; surface tension, σ = 0.028 N·m1) containing silica particles (mean particle diameter dp = 38 μm) has been studied in columns of three different diameters, 0.1, 0.19 and 0.38 m. With increasing particle concentration, the total gas hold‐up decreases significantly. This decrease is primarily caused by the destruction of the small bubble population. The hold‐up of large bubbles is practically independent of the slurry concentration. The measured gas hold‐up with the 36% v paraffin oil slurry shows remarkable agreement with the corresponding data obtained with Tellus oil (ρL = 862 kg/m3; μL = 0.075 Pa·s; σ = 0.028 N·m?1) as the liquid phase. Dynamic gas disengagement experiments confirm that the gas dispersion in Tellus oil also consists predominantly of large bubbles. The large bubble hold‐up is found to decrease significantly with increasing column diameter. A model is developed for estimation of the large bubble gas hold‐up by introduction of an wake‐acceleration factor into the Davies‐Taylor‐Collins relation (Collins, 1967), describing the influence of the column diameter on the rise velocity of an isolated spherical cap bubble. 相似文献
A comparative study on transition metal‐catalyzed cycloisomerizations of propargylic ureas derived in situ from secondary propargylic amines and tosyl isocyanate was performed. The influence of catalytic system on the reaction outcome was thoroughly studied on two model examples resulting in the establishment of two selective protocols for both O‐ and N‐cyclizations. The application of cationic gold(I) catalysis generally resulted in a formation of oxazolidin‐2‐imines as major products while the application of silver(I) triflate selectively provided the corresponding imidazolidin‐2‐ones. An attempt to rationalize the observed chemoselectivity is described. The scope of both processes was demonstrated through the use of variously substituted secondary propargylic amines. 相似文献
