We investigated the nature of the freezing in the geometrically frustrated Heisenberg spin glass Y2(Mo2)O(7) by measuring the temperature dependence of the static internal magnetic field distribution above the spin-glass temperature, Tg, using the muon spin relaxation technique. The evolution of the field distribution cannot be explained by changes in the spin susceptibility alone and suggests a lattice deformation. This possibility is addressed by numerical simulations of the Heisenberg Hamiltonian with magnetoelastic coupling at T > 0. 相似文献
A polymer therapeutic designed for combination anticancer and antiangiogenic therapy inhibited the proliferation of prostate carcinoma cells and the proliferation, migration, and tube‐formation of endothelial cells. The nanoconjugate was formed from an N‐(2‐hydroxypropyl)methacrylamide (HPMA) copolymer, the bisphosphonate alendronate (for bone targeting), and the chemotherapy agent paclitaxel (PTX), which is cleaved by cathepsin B (see scheme).
A solid state synthesis for obtaining nanocrystalline silicon was performed by high temperature reduction of commercial amorphous nanosilica with magnesium powder. The obtained silicon powder contains crystalline silicon phase with lattice spacings characteristic of diamond cubic structure (according to high resolution TEM), and an amorphous phase. In 29Si CP MAS NMR a broad multicomponent peak corresponding to silicon is located at −61.28 to −69.45 ppm, i.e. between the peaks characteristic of amorphous and crystalline Si. The powder has displayed red luminescence while excited under UV illumination, due to quantum confinement within the nanocrystals. The silicon nanopowder was successfully dispersed in water containing poly(vinyl alcohol) as a stabilizing agent. The obtained dispersion was also characterized by red photoluminescence with a band maximum at 710 nm, thus enabling future functional coating applications. 相似文献
When poly(2‐vinyl pyridine) is combined with Pd‐pincer‐based organometallic surfactants, a mesomorphic structure forms due to weak stacking interactions between the pyridine units and the Pd‐pincer headgroups. The weak binding between the surfactant and the polymer competes with the tendency of the aliphatic tails of the surfactant to crystallize. Here, we demonstrate that over extended periods of incubation, the crystallization tendency of the surfactant tails causes the surfactant molecules to detach from the polymer and gives rise to additional packing modes of the alkyl tails featuring higher crystalline order. The dynamic behavior of these aged structures was investigated by variable‐temperature small‐angle X‐ray scattering (SAXS) and solid‐state 13C NMR, and revealed the influence of thermal changes on the molecular level, and how these changes propagate to the mesoscale structure. 相似文献