A single-chip 900-MHz spread-spectrum wireless transceiver in1-μm CMOS. I. Architecture and transmitter design

A single-chip transceiver for frequency-hopped code division multiple access (CDMA) in the 900 MHz industrial, scientific and medical (ISM) band is implemented in 1-μm CMOS. It combines a digital frequency synthesizer, a double quadrature upconverter, an integrated oscillator, and a power amplifier with variable output. Data modulates a carrier hopping at 20 kHz with quaternary frequency-shift keying (4-FSK). At an output power level of +3 dBm, the harmonics and spurious tones lie at -52 dBc or below. When active, the transmitter drains 100 mA from 3 V     

Two gates are better than one [double-gate MOSFET process]

A planar self-aligned double-gate MOSFET process has been implemented where a unique sidewall source/drain structure (S/D) permits self-aligned patterning of the back-gate layer after the S/D structure is in place. This allows coupling the silicon thickness control inherent in a planar, unpatterned layer with VLSI self-alignment techniques and also gives independently controlled front and back gates. The demanding structure led to process innovations primarily in front-end CMP, where planarity within 5 nm was achieved on an 8-in diameter wafer as well as in silicided silicon source/drain sidewalls, with minimal encroachment of the silicide. Double-gate FET (DGFET) operation is demonstrated, with good transport at both interfaces. Dense circuit layouts are achieved with multifinger devices, and logic inverters with back-gate-controlled load current as well as NOR logic using the two gates of a single transistor as inputs are demonstrated.     

Photo‐curing behaviors of bio‐based isosorbide dimethacrylate by irradiation of light‐emitting diodes and the physical properties of its photo‐cured materials

Bio‐based isosorbide (1,4:3,6‐dianhydroglucitol), which was obtained from biomass‐derived carbohydrates, has recently attracted much attention as an alternative to bisphenol A (BPA) because of its rigidity and transparency. BPA is still widely used for a variety of chemical applications even though it is known to be an endocrine‐disrupting chemical. BPA is a key precursor to most photo‐curable materials ranging from encapsulants of electronic devices to dental sealants. In this study, photo‐curable isosorbide dimethacrylate (ISDM) was synthesized from bio‐based isosorbide as a substitute for BPA, and the photo‐curing behaviors of ISDM by irradiation with light‐emitting diode (LED) light were investigated. The photo‐curing conversion and rates of ISDM formation were determined based on the change in the peak corresponding to the double bond within the methacrylate groups using attenuated total reflectance Fourier transform infrared (ATR–FTIR) spectroscopy. The effects of initiators and the wavelength of LED light on the photo‐curing conversion and rates of ISDM formation were examined, and a comparative study was carried out with 2,2‐bis[4(2‐hydroxy‐3‐methacryloyloxy‐propyloxy)phenylpropane] (Bis‐GMA), which is a photo‐curing material bearing a BPA moiety. In addition, the mechanical properties, such as surface hardness, adhesion strength, and transparency, after photo‐curing of ISDM were evaluated. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42726.     

Hollow mesoporous Ia3d silica nanospheres with singleunit-cell-thick shell: Spontaneous formation and drug delivery application

Mesoporous silica nanoparticles (MSNs) are promising for drug delivery and other biomedical applications owing to their excellent chemical stability and biocompatibility. For these applications, a hollow morphology with thin shell and open mesopores is preferred for MSNs in order to maximize the loading capacity of drugs. Herein we report a novel and direct synthesis of such an ideal drug delivery system in a dilute and alkaline solution of benzylcetyldimethylammonium chloride and diethylene glycol hexadecyl ether. The mixed surfactants can guide the formation of MSNs with cubic Ia3d mesostructure, and at a concentration of sodium hydroxide between 9.8 and 13.5 mM, hollow MSNs with uniform sizes of 90–120 nm and a single-unit-cell-thick shell are formed. A mechanism for the formation of the hollow Ia3d MSNs, designated as MMT-2, is proposed based on in situ small-angle X-ray scattering measurements and other analyses. MMT-2 exhibits much higher loading capacity of ibuprofen and degrades faster in simulated body fluid and phosphate buffered saline than non-hollow MSNs. The degradation of MMT-2 can be significantly retarded by modification with polyethylene glycol. More interestingly, the degradation of MMT-2 involves fragmentation instead of void formation, a phenomenon beneficial for their elimination. The results demonstrate the uniqueness of the hollow Ia3d MSNs and the great potential of the material for drug delivery and biomedical applications.      

Ionic Potential： A General Material Criterion for the Selection of Highly Efficient Arsenic Adsorbents

Arsenic is a highly toxic element and its contamination in water bodies is a worldwide problem. Arsenic adsorption with metal oxides/hydroxides-based adsorbents is an effective approach to remove arsenic species from water for the health of both human beings and the environment. However, no material criterion had been proposed for the selection of potential candidates. Equally puzzling is the fact that no clear explanation was available on the poor arsenic adsorption performance of some commonly used adsorbents, such as active carbon or silica. Furthermore, in-depth examination was also not available for the dramatically different competing adsorption effects of various anions on the arsenic adsorption. Through the arsenic adsorption mechanism study on these highly efficient arsenic adsorbents, we found that ionic potential could be used as a general material criterion for the selection of highly efficient arsenic adsorbents and such a criterion could help us to understand the above questions on arsenic adsorbents. This material criterion could be further applied to the selection of highly efficient adsorbents based on ligand exchange between their surface hydroxyl groups and adsorbates in general, which may be used for the prediction of novel adsorbents for the removal of various contaminations in water.     

HARQ–ARQ interaction method for LTE‐based mobile satellite communication system

Hybrid automatic repeat request (HARQ) and automatic repeat request (ARQ) of the terrestrial long‐term evolution (LTE) system are designed considering the very short propagation delay of terrestrial environment. Therefore, when HARQ and ARQ are applied to the LTE‐based mobile satellite communication system, the inefficiency is caused by the long propagation delay of satellite environment. This paper proposes the interaction method between HARQ and ARQ for the decrease of inefficiency in the LTE‐based mobile satellite communication system. The existing concept of layered architecture about HARQ and ARQ is also maintained in our interaction method. Simulation results reveal that our proposed scheme can provide the larger spectrum efficiency than that of the non‐interaction scheme in all environments. The performance improvement can be up to 2.04 times through the interaction method. Copyright © 2014 John Wiley & Sons, Ltd.     

Multi‐Charged Conjugated Polyelectrolytes as a Versatile Work Function Modifier for Organic Electronic Devices

Despite the excellent work function adjustability of conjugated polyelectrolytes (CPEs), which induce a vacuum level shift via the formation of permanent dipoles at the CPE/metal electrode interface, the exact mechanism of electron injection through the CPE electron transport layer (ETL) remains unclear. In particular, understanding the ionic motion within the CPE ETLs when overcoming the sizable injection barrier is a significant challenge. Because the ionic functionality of CPEs is a key component for such functions, a rigorous analysis using highly controlled ion density (ID) in CPEs is crucial for understanding the underlying mechanism. Here, by introducing a new series of CPEs with various numbers of ionic functionalities, energy level tuning at such an interface can be determined directly by adjusting the ID in the CPEs. More importantly, these series CPEs indicate that two different mechanisms must be invoked according to the CPE thickness. The formation of permanent interfacial dipoles is critical with respect to electron injection through CPE ETL (≤ 10 nm, quantum mechanical tunneling limit), whereas electron injection through thick CPE ETL (20–30 nm) is dominated by the reorientation of the ionic side chains under a given electric field.     

Hydrogen from aluminium in a flow reactor for fuel cell applications

Aluminium appears to be a promising material for on-board hydrogen generation in fuel cell applications given the comparatively large amount of hydrogen produced per gram of aluminium in a safe system. A microfuel processor with aluminium and water as reactants is developed in a flow reactor for application in portable power sources. Two types of reactor are used. One reactor permits the direct feeding of liquid water in channels containing aluminium pellets, whereas the other utilizes the heat produced from the reaction to vapourize liquid water before entry into the reactor. Two additives, namely, calcium oxide (CaO) and sodium hydroxide (NaOH), are used to enhance the reaction rate. A maximum conversion of 78.6% with respect to aluminium is achieved when the water entering in the reactor is vapourized partially. In the case of liquid water entering the reactor, the conversion is 74.4%.     

The design,synthesis and nonlinear optical properties of a novel,Y-type polyurethane containing tricyanovinylthiophene of high thermal stability

A novel, Y-type polyurethane containing 1-(2,4-dioxyethoxy)phenyl-2-{5-(2,2-dicyanovinyl)-2-thiophenyl}ethenes as nonlinear optical chromophores present within the polymer backbone, was prepared and characterized. The compound was soluble in common organic solvents and displayed thermal stability up to 260 °C and a glass transition temperature (T_g) of 163 °C. The second harmonic generation coefficient (d₃₃) of poled polymer films at the compound's fundamental wavelength of 1560 nm was ～3.72 × 10^?9 esu. Dipole alignment exhibited high thermal stability up to the T_g, and there was no decay in d₃₃ below 148 °C owing to the partial main-chain character of the polymer structure.