Extremely bendable, high-performance integrated circuits using semiconducting carbon nanotube networks for digital, analog, and radio-frequency applications

Solution-processed thin-films of semiconducting carbon nanotubes as the channel material for flexible electronics simultaneously offers high performance, low cost, and ambient stability, which significantly outruns the organic semiconductor materials. In this work, we report the use of semiconductor-enriched carbon nanotubes for high-performance integrated circuits on mechanically flexible substrates for digital, analog and radio frequency applications. The as-obtained thin-film transistors (TFTs) exhibit highly uniform device performance with on-current and transconductance up to 15 μA/μm and 4 μS/μm. By performing capacitance-voltage measurements, the gate capacitance of the nanotube TFT is precisely extracted and the corresponding peak effective device mobility is evaluated to be around 50 cm(2)V(-1)s(-1). Using such devices, digital logic gates including inverters, NAND, and NOR gates with superior bending stability have been demonstrated. Moreover, radio frequency measurements show that cutoff frequency of 170 MHz can be achieved in devices with a relatively long channel length of 4 μm, which is sufficient for certain wireless communication applications. This proof-of-concept demonstration indicates that our platform can serve as a foundation for scalable, low-cost, high-performance flexible electronics.     

Self-Aligned, Extremely High Frequency III-V Metal-Oxide-Semiconductor Field-Effect Transistors on Rigid and Flexible Substrates

This paper reports the radio frequency (RF) performance of InAs nanomembrane transistors on both mechanically rigid and flexible substrates. We have employed a self-aligned device architecture by using a T-shaped gate structure to fabricate high performance InAs metal-oxide-semiconductor field-effect transistors (MOSFETs) with channel lengths down to 75 nm. RF measurements reveal that the InAs devices made on a silicon substrate exhibit a cutoff frequency (f(t)) of ～165 GHz, which is one of the best results achieved in III-V MOSFETs on silicon. Similarly, the devices fabricated on a bendable polyimide substrate provide a f(t) of ～105 GHz, representing the best performance achieved for transistors fabricated directly on mechanically flexible substrates. The results demonstrate the potential of III-V-on-insulator platform for extremely high-frequency (EHF) electronics on both conventional silicon and flexible substrates.     

Cytotoxic effects of 7-O-butyl naringenin on human breast cancer MCF-7 cells

The effect of 7-O-butyl naringenin (BN), a chemically synthesized derivative of naringenin, was tested on the proliferation of human breast cancer MCF-7 cells. BN inhibited the proliferation of MCF-7 cells in dosedependent manner (IC₅₀: 67.5±2.1 μM), resulting in an increase in the sub-G1 phase cell population. BN induced the generation of intracellular reactive oxygen species (ROS), which were reduced by pretreatment with N-acetylcysteine (NAC). BN also increased the phosphorylation of stress-activated protein kinase/c-Jun NH₄-terminal kinase 1/2 (SAPK/JNK1/2), c-Jun, and p38. However, the phosphorylation of extracellular-regulated kinase 1/2 (Erk1/2) was decreased in BN-treated cells. Pretreatment of cells with the specific inhibitors SP600125 and SB203580 diminished the BN-induced activation of SAPK/JNK1/2 and p38, respectively. These results indicate that the BN-induced cytotoxicity of MCF-7 cells is mediated by the generation of ROS as well as through the p38, SAPK/JNK1/2, and c-Jun activation signaling pathways. BN may therefore possess chemotherapeutic potential as an anti-proliferative agent.     

A simple synthesis of magnetically modified zeolite

A composite of zeolite with magnetite was prepared by urethane coating. Formation of magnetic modified zeolite (MMZ) was confirmed by magnetization measurements and X-ray diffraction (XRD) pattern analysis. Also, scanning electron microscopic (SEM) analysis reveals the presence of zeolite and magnetite particles. It is thought that approximately 16% urethane polymer is retained in composite particle as a result of thermogravimetric analysis (TGA).     

Properties of styrene ionomers containing zwitterion-type salts

Summary The properties of poly(styrene-co-styrenesulfonic acid) (PSSA) ionomers mixed with NaOH and p-aminobenzoic acid (ABA) were investigated dynamic mechanically. It was found that when NaOH was added to the PSSA+ABA solution to neutralize two acid groups, the properties of the blends were similar to those of Na-sulfonated polystyrene ionomer. In these blend systems, the Na-aminobenzoate probably acted as filler. In the blend of the PSSA polymer and Na-aminobenzoate, it was suggested that the so-called core-shell type multiplets form. However, when Na-sulfonated polystyrene was mixed with the ABA, the ABA molecules acted as a polar plasticizer. It was also found that in the blend system of PSSA+ABA partly neutralized with NaOH, the property fell somewhere between those of the two latter blend systems. Received: 24 July 1998/Revised version: 7 September 1998/Accepted: 16 September 1998     

Molecular dynamics simulations of oxidized vapor-grown carbon nanofiber surface interactions with vinyl ester resin monomers

Surface oxidation effects on the liquid vinyl ester (VE) monomer distributions near two oxidized vapor-grown carbon nanofiber (VGCNF) surfaces were studied using molecular dynamics simulations. Two overlapping graphene sheets containing oxygenated functional groups represented the oxidized VGCNF surfaces. Two liquid VE bisphenol-A dimethacrylates (designated VE1 and VE2, respectively) and styrene constituted the resin. Temporally and spatially averaged relative monomer concentrations, calculated in a direction away from the oxidized graphene surfaces, showed increased styrene and VE1 concentrations. Monomer molar ratios found within a 10 Å thick region adjacent to the oxidized graphene sheets were substantially different from those in the bulk resin. Curing should result in the formation of a very thin interphase region of different composition. The crosslink structure of such an interphase will be distinct from that of an unoxidized VGCNF surface. The enhanced VE1 concentration near this oxidized surface should give a higher crosslink density, leading to a stiffer interphase than that adjacent to unoxidized VGCNF surfaces. VGCNF–matrix adhesion may also be modified by the different interphase monomer molar ratios. These studies may facilitate multiscale material design by providing insight into carbon nanofiber–matrix interactions leading to improved macroscale composite properties.     

A 1.4‐Gbps intra‐panel interface with low‐power and low‐EMI schemes for Tablet PC applications

An intra‐panel interface addressing all of the high‐speed, low‐power, and low‐electromagnetic interference (EMI) requirements for tablet personal computer applications is presented. This work proposes an adaptive clock window scheme to achieve 1.4‐Gbps data‐rate. For EMI suppression, data scrambling, horizontal blank period pattern scrambling, and novel clock and data recovery circuit are introduced. Lastly, for power‐saving, the proposed interface dynamically biases source driver's output buffers and employs early charge sharing by controlling the configuration data. For verification, a WQXGA thin‐film transistor liquid crystal display system is implemented with the timing controller and source driver ICs that are fabricated using 65‐nm and 180‐nm complementary metal‐oxide semiconductor (CMOS) processes, respectively. The liquid crystal display system demonstrates maximum operation speed of 1.4 Gbps and suppression of EMI noise in LTE Band‐20 and GSM 850 bands. The proposed power‐saving schemes achieve 4.3% reduction in total power consumption by source driver IC, which reaches about 85% of power consumption by enhanced reduced‐voltage differential signaling interface circuit.     

Campaign Ads, Online Messaging, and Participation: Extending the Communication Mediation Model

Political communication researchers have devoted a great deal of attention to the role of political advertising, the Internet, and political discussion in civic and political life. In this article, we integrate and extend this research by developing a campaign communication mediation model of civic and campaign participation. Two data sets are merged for this inquiry: (a) content-coded ad-buy data on the placement of campaign messages on a market-by-market and program-by-program basis and (b) a national panel study concerning patterns of traditional and digital media consumption and levels of civic and campaign participation. Exposure to televised campaign advertising is estimated by developing an algorithm based on the market and program placement of specific ads and geocoded survey respondents' viewing of certain categories of television content in which these ads were concentrated. Structural equation models reveal that advertising exposure drives online news use in ways that complement conventional news influences on political discussion and political messaging. However, campaign exposure emphasizing "attack" messages appears to diminish information seeking motivations via broadcast and print media, yet only indirectly and weakly suppresses participation in civic and political life. Further, alternative specifications reveal that our original model produces the best fit, empirically and theoretically. We use these insights to propose an O-S-R-O-R (orientations-stimuli-reasoning-orientations-responses) framework as an alternative to the longstanding O-S-O-R model in communication and social psychology.     

A study on coining processes of solder bumps on organic substrates

Solder flip chip bumping and subsequent coining processes on printed circuit board (PCB) were investigated to solve the warpage problem of organic substrates for high pin count flip chip assembly by providing good co-planarity. Coining of solder bumps on PCBs has been successfully demonstrated using a modified tension/compression tester with height, coining rate and coining temperature variables. It was observed that applied loads as a function of coined height showed three stages as coining deformation; region of elastic deformation; region of linearly increase of applied loads; region of rapidly increase of applied loads. In order to reduce applied loads for coining solder bumps on a PCB, the effects of coining process parameters were investigated. Coining loads for solder bump deformation strongly depended on coining rates and coining temperatures. As coining rates decreased and process temperature increased, coining loads decreased. Lower coining loads were needed to prevent potential substrate damages such as micro-via failure and build-up dielectric layer thickness change during applying coining loads. It was found that coining process temperature had more significant effect to reduce applied coining loads during the coining process.     

Electrochemical performance of Mn3O4 nanorods by N-doped reduced graphene oxide using ultrasonic spray pyrolysis for lithium storage

The crumpled N-doped reduced graphene oxide wrapped Mn₃O₄ nanorods (Mn-NrGO) composite are synthesized via a combination of spray pyrolysis and a hydrothermal process for lithium ion batteries. The Mn₃O₄ nanorods are uniformly dispersed in the conductive matrix of crumpled N-doped reduced graphene oxide, forming a uniform wrapped composite and stopping them from restacking, which synergistically enhanced the Li⁺ ion conductivity. The well-defined Mn₃O₄ nanorods, strong interaction between Mn₃O₄ and NrGO, and highly graphitic properties of Mn-NrGO result in superior reversible capacity, long cycle life, and superior rate performance of approximately 1500 mAh/g at 0.1 C after 100 cycles and >660S mAh/g at 1.0 C after 500 cycles.