Abstract-In this paper we demonstrate an energy-reduction strategy that relies on the stochastic long-tail nature of the STT-RAM write operation. To move away from the traditional worst-case approach, the per-cell write process is continuously monitored and is terminated as soon as each cell's state matches the written state. Since the average write duration is far shorter than the worstcase duration, the average write energy is significantly reduced by the proposed architecture. We developed a light-weight circuit for fast state change detection and bit-line shutdown and evaluated it using a compact STT-RAM model targeting an implementation in a 16nm technology node. Our analysis indicates that at the required write-error rate the proposed architecture reduces write energy by 87.3% − 99.5% depending on the write direction, and on average achieves 96.5% write energy saving in 16 SPEC CPU 2006 applications compared to conventional design. Compared to the best previously known architecture that exploits stochasticity (verify-on-write), we reduce write energy by approximately 6.5×.
The extraction condition of curcumin from Curcuma longa L was optimized through four factors and three levels orthogonal experiment based on the results of single factor tests. Under the optimal conditions: the concentration of ethanol 80%, extraction temperature 70 • C, the ratio of liquid to material 20, and extraction time 3 h, a crude extract with the yield of curcumin 56.8 mg/g could be obtained. The isolation and purification of curcuminoids from the crude extract was performed on high performance counter current chromatography employing an optimized solvent system nhexane/ethyl acetate/methanol/water (2/3/3/1, v/v/v/v). From 97 mg crude sample (in which the purity of curmumin was 68.56%), 67 mg curmumin, 18 mg demethoxycurcumin, and 9.7 mg bisdemethoxycurcumin with a high-performance liquid chromatography purity of 98.26, 97.39, and 98.67%, respectively, were obtained within 70 min. The antioxidant activities and cytotoxicity of purified curcumin was comparable to that of the commercial product, indicating that the biological activity of curcumin could be maintained by this method.
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