Origin of nanosized diamonds in interstellar space and low-pressure-temperature Earth rocks

Nanosized diamond particles in the interstellar space and in the Earth rocks related with water presence. In the paper proposed the model of the nanosized diamond particle formation from oxidized water-carbon dioxide gaseous mixtures

Metastable Nanosized Diamond Formation from Fluid Systems

The model of nanosized diamond particles formation at metastable P-T parameters from fluid is presented. It explains the specific of CVD diamond synthesis gases mixtures and hydrothermal growth of diamond at low P-T parameters as well as it explains the geneses of metamorphic and magmatic nano- and microdiamond in the shallow depth Earth rocks and the genesis of interstellar nanodiamond formations in the space

Modelling and simulation on the tool wear in nanometric cutting

Tool wear is a significant factor affecting the machined surface quality. In this paper, a Molecular Dynamics (MD) simulation approach is proposed to model the wear of the diamond tool in nanometric cutting. It includes the effects of the cutting heat on the workpiece property. MD simulation is carried out to simulate the nanometric cutting of a single crystal silicon plate with the diamond tip of an Atomic Force Microscope (AFM). The wear mechanism is investigated by the calculation of the temperature, the stress in the diamond tip, and the analysis of the relationship between the temperature and sublimation energy of the diamond atoms and silicon atoms. Microstrength is used to characterize the wear resistance of the diamond tool. The machining trials on an AFM are performed to validate the results of the MD simulation. The results of MD simulation and AFM experiments all show that the thermo-chemical wear is the basic wear mechanism of the diamond cutting tool

Microwave-assisted cross-polarization of nuclear spin ensembles from optically-pumped nitrogen-vacancy centers in diamond

The ability to optically initialize the electronic spin of the nitrogen-vacancy (NV) center in diamond has long been considered a valuable resource to enhance the polarization of neighboring nuclei, but efficient polarization transfer to spin species outside the diamond crystal has proven challenging. Here we demonstrate variable-magnetic-field, microwave-enabled cross-polarization from the NV electronic spin to protons in a model viscous fluid in contact with the diamond surface. Slight changes in the cross-relaxation rate as a function of the wait time between successive repetitions of the transfer protocol suggest slower molecular diffusion near the diamond surface compared to that in bulk, an observation consistent with present models of the microscopic structure of a fluid close to a solid interface.Comment: 7 pages, 4 figure

The Gaussian Multiple Access Diamond Channel

In this paper, we study the capacity of the diamond channel. We focus on the special case where the channel between the source node and the two relay nodes are two separate links with finite capacities and the link from the two relay nodes to the destination node is a Gaussian multiple access channel. We call this model the Gaussian multiple access diamond channel. We first propose an upper bound on the capacity. This upper bound is a single-letterization of an $n$-letter upper bound proposed by Traskov and Kramer, and is tighter than the cut-set bound. As for the lower bound, we propose an achievability scheme based on sending correlated codes through the multiple access channel with superposition structure. We then specialize this achievable rate to the Gaussian multiple access diamond channel. Noting the similarity between the upper and lower bounds, we provide sufficient and necessary conditions that a Gaussian multiple access diamond channel has to satisfy such that the proposed upper and lower bounds meet. Thus, for a Gaussian multiple access diamond channel that satisfies these conditions, we have found its capacity.Comment: submitted to IEEE Transactions on Information Theor