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Activity-Driven Fine-Grained Clock Gating and Run Time Power Gating Integration
Li Li,Ken Choi,Haiqing Nan IEEE 2013 IEEE transactions on very large scale integration Vol.21 No.8
<P>As the two most widely used techniques to reduce dynamic power and leakage power, clock gating (CG) and power gating (PG), respectively, are expected to be integrated together effectively. Normally, the implementation of CG leads to some redundant operations, which provides the opportunity to apply PG. In this brief, we have proposed an activity-driven fine-grained CG and PG integration. First, we introduce an optimized bus-specific-clock-gating (OBSC) scheme to improve traditional XOR-based CG. It chooses only a subset of flip-flops (FFs) to be gated selectively, and the problem of gated FF selection is reduced from exponential complexity into linear. Then those combinational logics, which completely depend on the outputs of gated FFs, are performing redundant operations. They can be power gated, and the clock enable signal generated by OBSC is used as the sleep signal. A minimum average idle time concept is proposed to determine whether the insertion of PG will lead to energy reduction. In order to evaluate our technique, we experimented on twenty ISCAS'89 circuits. The simulation results show that 25.07% dynamic power can be reduced by OBSC, and 50.19% active leakage power can be saved by PG.</P>
Li, Haiqing,Cooper-White, Justin J.,Kim, Il The Royal Society of Chemistry 2013 SOFT MATTER Vol.9 No.21
<P>Using a mono-pyrene terminated hyperbranched polyglycidol (mPTHP) as a building block, one-dimensional (1D) mPTHP and mPTHP/gold nanoparticle (Au NP) nanostructures are fabricated in the presence of HAuCl<SUB>4</SUB>. By simply mixing mPTHP and different concentrations of aqueous HAuCl<SUB>4</SUB> solution at room temperature, mPTHP nanofibers and nanotubes are obtained through Au(<SMALL>III</SMALL>) ion induced self-assembly processes. Upon elevating the reaction temperature from room temperature to 60 °C, Au NPs are <I>in situ</I> generated within 1D mPTHP assemblies <I>via</I> an analogous “polyol process”, forming mPTHP/Au NP hybrid nanofibers and nanotubes. Careful control of the HAuCl<SUB>4</SUB> concentration enables <I>in situ</I> generated Au NPs to be either distributed along the center-line of nanofibers or symmetrically aligned into a double-line along the nanofibers and the inner surface of nanotubes. Further investigation reveals that the involvement of a small amount of NaBr in the reaction system of mPTHP and different amounts of HAuCl<SUB>4</SUB> results in the formation of <I>pseudo</I>-nanotubes decorated with double-lined Au NP chains along their inner surfaces. Moreover, the size of Au NPs can be effectively tuned in terms of HAuCl<SUB>4</SUB> concentration. All 1D mPTHP and mPTHP/Au NP nanostructures described in our current work are achieved through one-pot aqueous reactions in the absence of any additional reducing agents, surfactants and organic solvents, so that they are facile, green and low-cost strategies. To the best of our knowledge, this is the first example to synthesize 1D hyperbranched polymer/metal NP hybrid nanostructures with controllable spatial distribution of NPs using such a facile and green protocol.</P> <P>Graphic Abstract</P><P>A facile and green protocol has been developed to <I>in situ</I> generate and controllably align Au nanoparticles within the one-dimensional self-assembled nanostructures of hyperbranched polymers. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c3sm50768h'> </P>
Li, Haiqing,Han, Lina,Cooper-White, Justin J,Kim, Il RSC Pub 2012 Nanoscale Vol.4 No.4
<P>Multipyrene terminated hyperbranched polyglycidol (mPHP) has been synthesized and used to non-covalently functionalize pristine graphene sheets (GSs) through π-π stacking interactions. Mediated by the mPHP layer, a variety of metal nanoparticles (Au, Ag and Pt) were in situ generated and deposited onto the surface-modified GS, yielding versatile GS/mPHP/metal nanohybrids. As typical examples, by simply controlling the concentration of HAuCl(4) used, Au nanostructures ranging from isolated spheres to a continuous film were created and coated onto the surface-modified GS. The studies on the fluorescence properties of resulting GS/mPHP/Au hybrid nanostructures reveal that the GS and controllable content of Au components in the hybrids can effectively quench the fluorescence emission of mPHP in a controlled manner. Further investigation indicates that GS/mPHP/Au hybrids are promising surface enhanced Raman scattering (SERS) substrates. The SERS activities of these hybrids depend on the contents and form of the Au. The GS/mPHP/Au hybrid containing continuous Au films exhibits the strongest SERS activity. GS/mPHP/Au hybrids are also used as efficient heterogeneous catalysts for the reduction of 4-NP, and demonstrate excellent catalytic performance. The detailed reaction kinetics and the reusability of such catalysts have also been investigated.</P>
Li, Haiqing,Han, Lina,Cooper-White, Justin,Kim, Il The Royal Society of Chemistry 2012 GREEN CHEMISTRY Vol.14 No.3
<P>Two completely green and facile strategies have been developed to decorate Pd nanoparticles onto carbon nanotubes (CNT) sidewalls <I>via</I> non-covalent interactions assisted with newly synthesized hyperbranched polymers (PiHPs). The resultant CNT/PiHP/Pd heterogeneous catalysts exhibit ultrahigh catalytic reactivity towards the reduction of 4-nitrophenol.</P> <P>Graphic Abstract</P><P>Two facile strategies have been developed to decorate Pd nanoparticles onto CNT sidewalls <I>via</I> non-covalent interactions assisted with newly synthesized hyperbranched polymers (PiHPs). The resultant CNT/PiHP/Pd heterogeneous catalysts exhibit ultrahigh catalytic reactivity towards the reduction of 4-nitrophenol. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2gc16359d'> </P>
Li, Haiqing,Bahuleyan, Bijal K.,Johnson, Renjith P.,Shchipunov, Yury A.,Suh, Hongsuk,Ha, Chang-Sik,Kim, Il Royal Society of Chemistry 2011 Journal of materials chemistry Vol.21 No.44
<P>An α-diimine compound (DC) bearing multiple hydroxyl and amine groups presents excellent self-assembly behavior, yielding DC self-assemblies with tunable morphologies ranging from solid spheres, nanotubes and capsules <I>via</I> hydrogen bonds and π–π stacking interactions. These DC self-assemblies provide promising multifunctional hosts for varied metal species. As a typical example, Au nanoparticles are <I>in situ</I> generated and accommodated into both solid and hollow DC self-assemblies by one-pot and two-step fabrication processes, respectively, resulting in the formation of solid and hollow DC/Au hybrid nanostructures. Both solid and hollow DC self-assemblies also enable host Ni(<SMALL>II</SMALL>) ions to generate DC/Ni(<SMALL>II</SMALL>) catalysts for the efficient production of porous polyethylene (PE) beads consisting of numerous PE microspheres. Moreover, the yielded PE beads replicate the textural morphologies of the original DC/Ni(<SMALL>II</SMALL>) catalysts. These DC self-assemblies also might be further utilized to host varied metal species to fabricate versatile DC/metal nanoparticle (Ag, Pt, Pd, <I>etc.</I>) hybrids and porous polyolefin beads with desired morphologies.</P> <P>Graphic Abstract</P><P>Supramolecular self-assemblies of a α-diimine complex are presented together with their applications as multifunctional host systems. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c1jm13081a'> </P>
Li, Haiqing,Ha, Chang-Sik,Kim, Il WILEY-VCH Verlag 2009 Macromolecular Rapid Communications Vol.30 No.3
<P>A versatile approach to fabricate monodisperse poly[styrene-co-(divinyl benzene)] (PS-co-DVB) microcapsules that contain a single gold nanoparticle (AuNP) has been demonstrated. Using the PS-co-DVB microcapsule as a microreactor, aqueous HAuCl<SUB>4</SUB> and NaBH<SUB>4</SUB> solutions are subsequently infiltrated. The size of the resulting AuNP inside of the PS-co-DVB microcapsules is easily tunable by controlling the repeated infiltration cycles of aqueous HAuCl<SUB>4</SUB> and NaBH<SUB>4</SUB>. PS-co-DVB microcapsules that contain a single silver and palladium nanoparticle are also obtained by following a similar protocol.</P><P> <img src='wiley_img/10221336-2009-30-3-MARC200800629-gra001.gif' alt='wiley_img/10221336-2009-30-3-MARC200800629-gra001'> </P>