Surface Energy Of Faces Research Articles

Spectrum-Quantified Morphological Evolution of Enzyme-Protected Silver Nanotriangles by DNA-Guided Postshaping.

Quantitative morphological evolution is of great importance in nanochemistry. In this work, morphology of silver nanotriangles (AgNTs) is quantitatively evolved under the guidance of DNA. First, intact AgNTs are prepared relying on the protection of horseradish peroxidase. Then different regions of AgNTs are sequentially etched by C-rich DNA, leading to DNA-guided postshaping of AgNTs. In combination with atomically resolved images and theoretical simulation, a model is established to track the postshaping process. Since real-time morphological evolution of AgNTs is determined with spectra, a series of AgNTs with specific corners can be obtained by controlling incubation time. The DNA-guided postshaping is sequence and structure dual-dependent, and a mechanism is proposed based on metal-base interaction, surface energy of faces, and freedom of DNA structure. In addition, the postshaping is further used to design DNA-mediated biosensors. This study provides a precise and quantitative method of controlling morphology of anisotropic metallic nanomaterials.

Anisotropy of microhardness of directionally crystallized materials based on lanthanum hexaboride

We show that hardness and strength of composite ceramic materials LaB6−MeB2 are defined by the strength of interatomic bonds between the matrix and fibers, mutual crystallographic orientation of the most strength directions in the matrix hexaboride and reinforcing diboride phases, dimensions and amount of reinforcing inclusions, and their stress-strain state. Increasing the fracture toughness by reinforcement with diboride fibers allows one to find the relation between the hardness of LaB6 crystal faces which decreases according toH(111)>H(110)>H(100), the surface energy of faces σ(111)>σ(110)>σ(100), and the number of bonds between boron atoms which appear upon fracture in the corresponding crystallographic directions. The regularities established make it possible to directionally choose the initial components and the technology of production of ceramic composite materials with preset properties based on the brittle compounds.