Arrays of anisotropic particles are sought after for applications in optics, electronics, and energy. Structures assembled from multiple micro‐ or nanoparticles could incorporate the distinct properties of each component to achieve functions not possible from single‐population assemblies. In mixed‐particle populations, the assembly forces may differ between the particle types, which will in turn influence the final assembled structures. Here, binary particle mixtures are studied and compared to assemblies formed from each of the component particles alone. The particles are partially etched nanowires (PENs, ≈300 nm diameter, and 3–8 μm overall length), which are formed by the silica coating and subsequent etching of striped metal nanowires, such that what remains are silica nanotubes containing segments of metal core (Au, Pt, Rh, or Pt/Au) with controllable location and number, spaced by “empty” regions that fill with water. Binary mixtures of PENs with different core metals and segment patterns are examined here to explore how the different core segment material, length, position, and number affects overall self‐assembly behavior. 相似文献
Magnetic particles (MPs) offer several advantages for neural cell therapy, but limited particle uptake by neural cells is a barrier to translation. It is recently proved that tailoring particle physicochemical properties (by enhancing their iron content) dramatically improves uptake in neural stem cells (NSCs)—a major transplant population. High‐throughput screening of particles with varying physicochemical properties can therefore aid in identifying particles with optimal uptake features, but research is hampered by the lack of simple methodologies for studying neural cell membrane responses to nanoparticle platforms. A high‐resolution–high throughput method has been used to study early membrane responses of primary rodent NSCs to particles of variant magnetite loading, to attempt to correlate these responses with known particle internalization profiles. Membrane imaging is enhanced through sequential staining with osmium (O) and thiocarbohydrazide (T), a method termed OTOTO, combined with field‐emission scanning electron microscopy (FESEM). A five‐point classification system was used to systematically evaluate early MP‐induced membrane responses to particles possessing distinct physicochemical properties. Significantly different profiles of membrane activation were noted that correlate with particle uptake profiles. It is suggested that our method can serve as a valuable predictor of particle internalization in neural cells for diverse particle platforms. 相似文献
Results of shock-dispersed-fuel (SDF) explosion experiments are presented. The SDF charge consisted of a spherical 0.5-g PETN booster surrounded by 1 g of fuel, either flake aluminum (Al) powder or TNT. The charge was placed at the center of a sealed chamber. Three cylindrical chambers (volumes of 6.6, 20, and 40 l with L/D = 1) and three tunnels (L/D = 3.8, 4.65, and 12.5) were used to explore the influence of chamber volume and geometry on completeness of combustion. Detonation of the SDF charge created an expanding cloud of explosion product gases and hot fuel (Al or TNT). When this fuel mixed with air, it formed a turbulent combustion cloud that consumed the fuel and liberated additional energy (31 kJ/g for Al or 15 kJ/g for TNT) over and above detonation of the booster (6 kJ/g) that created the explosion. Static pressure gauges were the main diagnostic. Pressure and impulse histories for explosions in air were much greater than those recorded for explosions in nitrogen—thereby demonstrating that combustion has a dramatic effect on the chamber pressure. This effect increases as the confinement volume decreases and the excess air ratio approaches values between 2 and 3.5. 相似文献
We have found the equation of the etch pit wall in solid state nuclear track detectors, as follows:
where: x is the distance along a track from the point where the particle entered the detector; V(x) is the ratio of the track etch rate to the bulk etch rate; C is the integration constant that can be determined from particle penetration depth, and y is the normal distance from the particle trajectory to the etch pit wall. The equation is derived assuming the increasing track etch rate Vt along the particle trajectory.
The above equation can be used for the simulation of the track growth and calculating the major and the minor axis of the etch pit opening. The corresponding computer program was set up. The input parameters of this program are: alpha particle energy, incidence angle and removed layer: the output are track parameters. The results obtained by this method are compared with another approach given by Somogyi and Szalay (1973) and reasonably good agreement is found. 相似文献
The bulk etch rate for two types of CR-39 detector was measured as a function of temperature and the activation energies of bulk etching was determined. Experimental values of track etch rate were derived directly from the function of the succesive measured track length vrs. etching time for 209Bi, 129Xe and 20Ne ions.
The maximum etchable length of 13 MeV/u 209Bi and 13.04 MeV/u 129Xe ions have been measured at and below these energies. A comparison of the measured and calculated track length data is presented. 相似文献
The molecular structure of SR-90 and CR-39 is very similar except that the average length of carbonate linkages in SR-90 is 1.6 times longer than in CR-39. However, the effect of vacuum and carbon dioxide (CO2) on the track registration of these two detectors is very different: 1) the sensitivity of CR-39 becomes very low in vacuum; the sensitivity of SR-90 does not go down to zero even after storage in vacuum for a long time; 2) the sensitivity of SR-90 decreases both in air and in vacuum but the original sensitivity can be restored by storing it in CO2 of 13 atm for several days. We also found that the sensitization of latent tracks by oxygen (O2) is effective only at the time of irradiation but the sensitization by CO2 is effective after irradiation. 相似文献
Track method (using the CN and CR-39 detectors, spark couner of tracks as well as selective sorbents for plutonium and uranium) is applied in 1994 and 1995 together with many other methods in radioecological monitoring of water in the region of the sunken nuclear submarine (NS) “Komsomolets”. The detection assembles were installed with the help of the submersibles MIR. The results obtained inside the NS and on its surface as well as near and on the remote buoy station do not contradict the data obtained by other methods confirming the absence of the plutonium leakage outside of the submarine. 相似文献
The quartz glass open chromatographic columns with thermal gradient, which usually were used for the investigation of chemical properties of short-lived Z104 nuclides, were first used as the track detectors of spontaneously fissioning isotopes of elements 104, 105 and 106. The recoil nuclei of these elements were captured by the flow of gaseous chlorides then go to the quartz tube with reducing thermal gradient 400°C-100°C. The quartz tube was etched in 40% HF. The tracks due to spontaneous fission of isotopes 259104, 262105 and 263106 which were etched at the internal wall of quartz tubes were counted under optical microscope. 相似文献
We study phase separation in a system of hard-core particles driven by a fluctuating two-dimensional self-affine potential landscape which evolves through Kardar–Parisi–Zhang (KPZ) dynamics. We find that particles tend to cluster together on a length scale which grows in time. The final phase-separated steady state is characterized by an unusual cusp singularity in the scaled correlation function and a broad distribution for the order parameter. Unlike the one-dimensional case studied earlier, the cluster-size distribution is asymmetric between particles and holes, reflecting the broken reflection symmetry of the KPZ dynamics, and has a contribution from an infinite cluster in addition to a power law part. A study of the surface in terms of coarse-grained depth variables helps understand many of these features. 相似文献