Inorganic Drug‐Delivery Nanovehicle Conjugated with Cancer‐Cell‐Specific Ligand

The surface of layered double hydroxide nanoparticles, a potential drug‐delivery nanovehicle, is modified with the cancer‐cell‐specific ligand, folic acid. The surface modification is successfully accomplished through step‐by‐step coupling reactions with aminopropyltriethoxysilane and 1‐ethyl‐3‐(3‐dimethyl aminopropyl)‐carbodiimide. In order to evaluate the cancer‐cell targeting effect of folic‐acid‐grafted layered double hydroxide utilizing fluorescence‐related assay, both layered double hydroxide with and without folic acid moiety are labeled with fluorescein 5′‐isothiocyanate. The uptake of layered double hydroxide and folic acid conjugated into KB and A549 cells is visualized using fluorescence microscopy and measured by flow cytometry. Both chemical and biological assay results demonstrate that the folic acid molecules are indeed conjugated to the surface of layered double hydroxide and thus the selectivity of nanovehicles to cancer cells overexpressing folate receptors increases. In this study, it is suggested that layered double hydroxide nanoparticles can be used as drug‐delivery carriers with a targeting function due to the chemical conjugation with specific ligand.     

Data retention characteristics of MANOS-type flash memory device with different metal gates at various levels of charge injection

We investigated the impact of charge injection and metal gates (Al and Pt) on the data retention characteristics of metal–alumina–nitride–oxide–silicon (MANOS) devices for NAND flash memory application. Through the theoretical and experimental results, the highly injected charge (ΔV_TH) could cause the band bending of Al₂O₃, which reduced the tunneling distance across Al₂O₃. Thus, the dominant charge loss path is not only toward SiO₂ but also toward Al₂O₃ direction. Compared to low-metal work function (Ф_M), ONA stack with high-Ф_M showed better data retention characteristics, even if ΔV_TH is high. This could be explained by Fermi level alignment for different Ф_M, which results in the reduction of electric field across the Al₂O₃ compensated by the ΔФ_M (Ф_Pt ? Ф_Al).     

Two-level protection and guarantee for multimedia traffic in IEEE 802.11e distributed WLANs

In order to support multimedia applications such as voice and video over the wireless medium, a contention-based channel access function, called Enhanced Distributed Channel Access (EDCA), has been developed in the emerging standard IEEE 802.11e. In the EDCA, differentiated channel access is provided for different traffic classes. In this paper, we propose a two-level protection and guarantee mechanism for voice and video traffic in the EDCA-based distributed wireless LANs. In the first-level protection, the existing voice and video flows are protected from the new and other existing voice and video flows via a distributed admission control with tried-and-known and early-protection enhancements. In the second-level protection, the voice and video flows are protected from the best-effort data traffic by adopting frame-based and limit-based data control mechanisms. Performance evaluations are conducted in terms of throughput, delay, transmission limit, number of collisions, and throughput square relative difference. Extensive simulation results demonstrate that the proposed two-level protection and guarantee mechanism is very effective in terms of the protection and guarantee of existing voice and video flows as well as the utilization of the channel capacity. An early version of this paper was presented at IEEE INFOCOM 2004.     

A Structurable Gel‐Polymer Electrolyte for Sodium Ion Batteries

In this work, a structurable gel‐polymer electrolyte (SGPE) with a controllable pore structure that is not destroyed after immersion in an electrolyte is produced via a simple nonsolvent induced phase separation (NIPS) method. This study investigates how the regulation of the nonsolvent content affects the evolving nanomorphology of the composite separators and overcomes the drawbacks of conventional separators, such as glass fiber (GF), which has been widely used in sodium ion batteries (SIBs), through the regulation of pore size and gel‐polymer position. The interfacial resistance is reduced through selective positioning of a poly(vinylidene fluoride‐co‐hexa fluoropropylene) (PVdF‐HFP) gel‐polymer with the aid of NIPS, which in turn enhances the compatibility between the electrolyte and electrode. In addition, the highly porous morphology of the GF/SGPE obtained via NIPS allows for the absorption of more liquid electrolyte. Thus, a greatly improved cell performance of the SIBs is observed when a tailored SGPE is incorporated into the GF separator through charge/discharge testing compared with the performance observed with pristine GF and conventional GF coated with PVdF‐HFP gel‐polymer.     

Low‐Power Nonvolatile Charge Storage Memory Based on MoS2 and an Ultrathin Polymer Tunneling Dielectric

Low‐power, nonvolatile memory is an essential electronic component to store and process the unprecedented data flood arising from the oncoming Internet of Things era. Molybdenum disulfide (MoS₂) is a 2D material that is increasingly regarded as a promising semiconductor material in electronic device applications because of its unique physical characteristics. However, dielectric formation of an ultrathin low‐k tunneling on the dangling bond‐free surface of MoS₂ is a challenging task. Here, MoS₂‐based low‐power nonvolatile charge storage memory devices are reported with a poly(1,3,5‐trimethyl‐1,3,5‐trivinyl cyclotrisiloxane) (pV3D3) tunneling dielectric layer formed via a solvent‐free initiated chemical vapor deposition (iCVD) process. The surface‐growing polymerization and low‐temperature nature of the iCVD process enable the conformal growing of low‐k (≈2.2) pV3D3 insulating films on MoS₂. The fabricated memory devices exhibit a tunable memory window with high on/off ratio (≈10⁶), excellent retention times of 10⁵ s with an extrapolated time of possibly years, and an excellent cycling endurance of more than 10³ cycles, which are much higher than those reported previously for MoS₂‐based memory devices. By leveraging the inherent flexibility of both MoS₂ and polymer dielectric films, this research presents an important milestone in the development of low‐power flexible nonvolatile memory devices.     

Corrugated Quantum-Well Infrared Photodetector Focal Plane Arrays

Corrugated quantum-well infrared photodetectors (C-QWIPs) have been proposed for long-wavelength infrared detection. In this work, we optimize the detector structure and produce a number of large format focal plane arrays (FPAs). Specifically, we adopt one-corrugation-per-pixel geometry to increase the active detector volume and incorporate a composite cover layer to preserve the large sidewall reflectivity, which results in a large detector quantum efficiency. We also optimize the detector material structure such as the final state energy, the doping density, and the number of quantum well periods to improve the FPA operation under the existing readout electronics. As a result, high FPA sensitivity has been achieved, and their characteristics are in agreement with the detector model. Based on this model, we perform a systematic analysis on the FPA performance with a wide range of detector and system parameters. We find that C-QWIP FPAs are capable of high-speed imaging especially for those with longer cutoff wavelengths.     

Phase Diversity for an Antenna-Array System With a Short Interelement Separation

This paper presents a simple procedure of obtaining a diversity gain in an antenna-array system with a short interelement separation, typically less than the carrier wavelength. The new technique provides a diversity gain through a noncoherent combination of received signals at each antenna element. The diversity gain arises because, as the number of signal components of the received signal at each antenna element becomes large enough and as the arrival angle of each signal component is distinct from one another, which is a general signal circumstance in most practical code division multiple access (CDMA) signal environments, the amplitudes of the received signals become nearly independent due to the phase difference among the received signals. The diversity gain was referred to as ldquophase diversityrdquo in this paper. The proposed technique is first theoretically analyzed to estimate the performance in terms of pseudorandom-noise-code acquisition, which is verified through extensive computer simulations. Then, through the experimental results that are obtained from a CDMA array-antenna base station system, it has been shown that the performance of noncoherent detection is proportionally improved to the number of antenna elements.     

Adaptive power saving mechanism considering the request period of each initiation of awakening in the IEEE 802.16e system

Performance of the IEEE 802.16 e power management is mainly affected by two operating parameters: the minimum sleep interval (T _min) and the maximum sleep interval (T _max), in sleep-mode operation. To enhance the performance, this letter proposes a new power saving mechanism, which adaptively controls these parameters by considering the request period of each initiation of awakening (Tint)- The numerical analysis and simulation results show that this mechanism can achieve better energy conservation with reasonable response delay of Medium Access Control (MAC) Service Data Units (SDUs) than the standard operation.