Novel CdClOH sub‐nanocone crystals were successfully synthesized on a large scale by a facile solution‐based method using polymers as crystal growth modifiers. The crystals showed cone‐like morphology. Some factors affecting the morphology and size of the product, such as reaction temperature, concentrations of polyacrylamide (PAM), and pH value of the solution, were systematically studied. Experiments implied that polymer PAM played a key role in the formation of CdClOH sub‐nanocones. A possible formation mechanism of CdClOH sub‐nanocones was suggested based on nucleation‐etching process‐recrystallization in a mild aqueous solution. Furthermore, the as‐prepared CdClOH sub‐nanocones could be further transformed into CdS hollow sub‐nanocones by an anion‐exchange reaction. 相似文献
We have theoretically investigated two-dimensional atom localization using the absorption spectra of birefringence beams of light in a single wavelength domain.The atom localization is controlled and modified through tunneling effect in a conductive chiral atomic medium with absorption spectra of birefringent beams.The significant localization peaks are investigated in the left and right circularly polarized beam.Single and double localized peaks are observed in different quadrants with minimum uncertainty and significant probability.The localized probability is modified by controlling birefringence and tunneling conditions.These results may be useful for the capability of optical microscopy and atom imaging. 相似文献
Nanoparticles may limit off-tumor/on-target ubiquitous activation of signaling by protein-based drugs. However, many challenges still exist in the design of a nanoparticle for protein delivery. In this study, conditions to establish vaterite nanoparticles as a pH-sensitive drug delivery system (DDS) for encapsulated protein drugs are comprehensively evaluated. Low coprecipitation pH of vaterite and protein prevents protein denaturation and yields high loading efficiency. Unprotected vaterite recrystallizes in aqueous solutions within 3 h to calcite and releases the loaded protein completely, but surface-modified particles with carboxyl groups containing polymers prove stable for more than 5 months. Notably, modification of vaterite with sulfonated polymers increases the loading of cationic proteins by a multiple. A system is developed for vaterite exposure to (pH) conditions under body-like-flow rates, with the dissolution of vaterite and simultaneous release of active proteins at tumor microenvironmental pH reaching up to 80% and only 20% at physiological pH within 2 h. Importantly, the immunomodulatory protein tumor necrosis factor preserves its native structure and fully retains functional activity in vitro after release from the particles. In conclusion, the studies described here provide a framework for the development of vaterite-based DDS as a carrier for bioactive protein-based therapeutics. 相似文献
Scientific interest in atomically controlled layer-by-layer fabrication of transition metal oxide thin films and heterostructures has increased intensely in recent decades for basic physics reasons as well as for technological applications. This trend has to do, in part, with the coming post-Moore era, and functional oxide electronics could be regarded as a viable alternative for the current semiconductor electronics. Furthermore, the interface of transition metal oxides is exposing many new emergent phenomena and is increasingly becoming a playground for testing new ideas in condensed matter physics. To achieve high quality epitaxial thin films and heterostructures of transition metal oxides with atomically controlled interfaces, one critical requirement is the use of atomically flat single terminated oxide substrates since the atomic arrangements and the reaction chemistry of the topmost surface layer of substrates determine the growth and consequent properties of the overlying films. Achieving the atomically flat and chemically single terminated surface state of commercially available substrates, however, requires judicious efforts because the surface of as-received substrates is of chemically mixed nature and also often polar. In this review, we summarize the surface treatment procedures to accomplish atomically flat surfaces with single terminating layer for various metal oxide substrates. We particularly focus on the substrates with lattice constant ranging from 4.00 Å to 3.70 Å, as the lattice constant of most perovskite materials falls into this range. For materials outside the range, one can utilize the substrates to induce compressive or tensile strain on the films and explore new states not available in bulk. The substrates covered in this review, which have been chosen with commercial availability and, most importantly, experimental practicality as a criterion, are KTaO3, REScO3 (RE = Rare-earth elements), SrTiO3, La0.18Sr0.82Al0.59Ta0.41O3 (LSAT), NdGaO3, LaAlO3, SrLaAlO4, and YAlO3. Analyzing all the established procedures, we conclude that atomically flat surfaces with selective A- or B-site single termination would be obtained for most commercially available oxide substrates. We further note that this topmost surface layer selectivity would provide an additional degree of freedom in searching for unforeseen emergent phenomena and functional applications in epitaxial oxide thin films and heterostructures with atomically controlled interfaces. 相似文献
Novel ‘nano in nano’ composites consisting of biodegradable polymer nanoparticles incorporated into polymer nanofibers may efficiently modulate drug delivery. This is shown here using a combination of model compound‐loaded biodegradable nanoparticles encapsulated in electrospun fibers. The dye coumarin 6 is used as model compound for a drug in order to simulate drug release from loaded poly(lactide‐co‐glycolide) nanoparticles. Dye release from the nanoparticles occurs immediately in aqueous solution. Dye‐loaded nanoparticles which are encapsulated by electrospun polymer nanofibers display a significantly retarded release.