Molecular velocity auto-correlation of simple liquids observed by NMR MGSE method

The velocity auto-correlation spectra of simple liquids obtained by the NMR method of modulated gradient spin echo show features in the low frequency range up to a few kHz, which can be explained reasonably well by a $t^{-3/2}$ long time tail decay only for non-polar liquid toluene, while the spectra of polar liquids, such as ethanol, water and glycerol, are more congruent with the model of diffusion of particles temporarily trapped in potential wells created by their neighbors. As the method provides the spectrum averaged over ensemble of particle trajectories, the initial non-exponential decay of spin echoes is attributed to a spatial heterogeneity of molecular motion in a bulk of liquid, reflected in distribution of the echo decays for short trajectories. While at longer time intervals, and thus with longer trajectories, heterogeneity is averaged out, giving rise to a spectrum which is explained as a combination of molecular self-diffusion and eddy diffusion within the vortexes of hydrodynamic fluctuations.Comment: 8 pages, 6 figur

64-kB 65-nm GC-eDRAM With Half-Select Support and Parallel Refresh Technique

Gain-cell-embedded DRAM (GC-eDRAM) is an attractive alternative to traditional 6T SRAM, as it offers higher density, lower leakage power, and two-ported functionality. However, its refresh requirement also results in power consumption and memory access limitations. In this letter, we present a GC-eDRAM architecture designed to overcome the refresh disadvantages using a novel technique for improving the availability of the memory. In addition, by using a read-before-write mechanism, half select is supported. The macro avoids the need for supply boosting by employing 3T-1C bitcells and also integrates a replica bit line for optimal access timing to improve performance and power consumption. A 64- kB GC-eDRAM macro was fabricated in a 65- nm process technology, providing a 40% area reduction compared to a 6T SRAM cell, while achieving a 99.99% bit yield with a 16 mu s retention time