A new compact LTCC bandpass filter using negative coupling

This letter presents the design and realization of a new compact bandpass filter (BPF) fabricated on multilayered ceramic substrates. This BPF features coupled resonators with negative coupling coefficients. A BPF with center frequency 2.45 GHz is designed and fabricated. Its size is only 2.0 mm/spl times/1.8 mm/spl times/0.67 mm when implemented by a standard low temperature co-fired ceramic technology. The size reduction is due to the higher coupling coefficient between the negatively-coupled resonators than the positively-coupled ones, allowing tighter space between the resonators. The measured insertion losses of the previous BPF were less than 3dB and return losses more than 18dB in the passband. The measured result agrees very well with the electromagnetic (EM) designed response.     

Novel fulleropyrrolidines bearing π-conjugated thiophene derivatives as compatibilizing group for developing highly stable polymer solar cells

A series of new fulleropyrrolidines, which comprise one terthiophene (3T) or dithienyl thienothiophene (2TTT) conjugated segment along with two hexyl (H) or ethylhexyl (EH) chains, abbreviated as 3T-H-C₆₀, 3T-EH-C₆₀, 2TTT-H-C₆₀ and 2TTT-EH-C₆₀, were designed and synthesized to improve their structural compatibility with poly(3-hexylthiophene) (P3HT). These [60]fullerene monoadducts exhibit a characteristic UV–Vis absorption band, associated with the conjugated substituent, and similar optical bandgaps and lowest unoccupied molecular orbital (LUMO) levels of approximately 1.71 eV and −3.72 eV, respectively. The influence of the structure of the substituent in the fulleropyrrolidine on its intermolecular packing within a polymer matrix was investigated. Photoluminescence measurements of the blended films of such C₆₀ derivatives with P3HT reveal that the interfacial area between the two materials is larger in the 3T-based system than in the 2TTT-based system; moreover, the branched ethylhexyl chain is more effective than the linear hexyl group in reducing the size of the phase domains. Transmission electron microscopic images further confirm that relatively serious phase segregation occurs in the 2TTT-C₆₀/P3HT films. Accordingly, solar cells with 3T-C₆₀/P3HT as the active layer have an increased short-circuit current density owing to improved exciton dissociation efficiency, but 2TTT-C₆₀/P3HT devices have a boosted fill factor, owing to the formation of less obstructed pathways for the transport of charge carriers. More interestingly, both 3T-EH-C₆₀/P3HT and 2TTT-EH-C₆₀/P3HT exhibit highly stable blend morphology and the solar cells that are derived from them have extremely steady power conversion efficiency against long-term aging at high temperature.     

A systematic study of the initial electrical and radiation hardnessproperties of reoxidized nitrided oxides by rapid thermalprocessing

The initial electrical and radiation hardness properties of MOS capacitors with reoxidized nitrided oxides (RNO) structures are systematically investigated by changing the pressure, temperature, and times of nitridation and reoxidation in rapid thermal processes. It was found that the initial flat-band voltage (V_fb) and midgap interface trap density (D_itm) are strongly dependent on the growth conditions and show concave or convex “turnaround” dependency on some process parameters. This may be explained by the hydrogen evaporation and oxygen passivation mechanisms. The radiation induced flat-band voltage shift (ΔV_fb) and midgap interface trap density shift (ΔD_itm) are also growth-condition dependent and show different “turnaround” dependencies on some process parameters from those observed in initial properties. This may be explained by the variations of the amount of hydrogen-related species such as Si-NH, Si-H, or Si-OH, and nitrogen-related species, such as Si-N, in the oxide bulk and at the Si/SiO₂ interface. Finally, the sample with a reoxidation pressure of 250 torr, a reoxidation temperature of 1050°C, and a reoxidation time of 100 s is suggested to be the most radiation-hard together with good initial properties for RNO devices     

Bluetooth: a new era of connectivity

The seemingly endless entanglement of data wires connecting today's electronic devices has become slightly less jumbled with the introduction. of Bluetooth technology and the creation of a wireless data link. If Bluetooth development can advance without having to confront any major hurdles, it will be poised to revolutionize and simplify the way in which electronic devices interact with one another.     

Langmuir-Blodgett films of palladium(II)-imidazole liquid crystals

The self-assembly of organic-inorganic compounds of palladium(II)-bis(N-long chain substituted imidazole) dichloride complexes has been investigated. The presence of a hydroxyl group at the 2-position of alkyl chain induced liquid crystal properties. Molecular ordering of Pd(II)-imidazole complexes upon mechanical compression at the air/water interface is studied by surface pressure-area (π-A) isotherms and Brewster angle microscope. Incorporation of lateral hydroxyl group in the alkyl chain enhances the stability of the films via intramolecular hydrogen bonding interactions. Langmuir-Blodgett (LB) films formed by these compounds were studied by various techniques to characterize their surface morphology, hydrophilic/hydrophobic property, surface functionalities and interlayer spacings. U-shaped interdigitated assembling, good crystallinity and in-air stability of these LB films were demonstrated.     

Design of microwave wide-band quadrature hybrid using planar transformer coupling method

A lumped-element quadrature hybrid consisting of two-section inductive coupled /spl pi/-networks is presented. A synthesizing method involving a new set of design equations are also developed to realize the proposed hybrid with very good balance in both magnitude and phase between the output ports over a 38% fractional bandwidth. The measurements of the two prototypes show quite good agreement with the theoretical predictions. The proposed hybrid is compact and suited to be implemented by conventional microwave-integrated-circuit technology.     

Reliable fluorinated thin gate oxides prepared by liquid phasedeposition following rapid thermal process

A reliable fluorinated thin gate oxide prepared by liquid phase deposition (LPD) following rapid thermal oxidation (RTO) in O₂ or nitridation (RTN) in N₂O ambient was reported. Fluorine (F) atoms incorporated into the oxides during LPD process are found to be helpful to the improvement of oxide quality. It is observed that these fluorinated gate oxides show good properties in radiation hardness, charge to breakdown (Q_bd), and oxide breakdown field (E_ox) endurances. Interestingly, the Q_bd 's for the fluorinated gate oxides are 10 times larger than those for the gate oxides prepared by RTO in O₂ or RTN in N₂ O directly. Some of the E_ox's are even higher than 17 MV/cm for the samples investigated in this work     

Survival hazards of road environment factors between motor-vehicles and motorcycles

Motorcycles are frequently used in middle- and low-income societies. They are often involved in crashes, and account for a noticeable percentage of fatalities secondary to crashes. Comparing motor-vehicle occupants and motorcycle riders, the present study examined the survival hazard of crash injuries with respect to road environmental factors (i.e., area, road type, and location). We investigated the effects of such factors on survival and survival time after crashes via a binary logistic regression analysis and a Cox proportional hazard regression analysis, respectively. Results indicated that, for both motor-vehicle occupants and motorcycle riders, the fatal prevalence, occurrence likelihood, and risk based on time were decreased in urban areas and elevated on highways. The three indexes were also higher for motor-vehicle occupants on non-straight or non-level roadway sections. The prevalence of death on local roads and at intersections was relatively higher for motorcycle riders compared to motor-vehicle occupants. Speed may contribute to the survival hazard with respect to road environment factors. Speed management initiatives account for hazardous roadway, curve alignment re-examination, and increased traffic enforcement density are suggested. Collaboration among the roadway authorities, vehicle industry, and medical systems for a timely rescue is also advised. In addition, the attention to crashes at intersections and on local roads is a promising intervention for motorcycle riders.     

Using data linkage to generate 30-day crash-fatality adjustment factors for Taiwan

Different countries have their own police reporting time standards for counting the number of fatalities in reported crashes. A rapid estimation method (such as adjustment factor) for the comparison is important. The data-linkage technique was used to combine police-reported crash data and vital registration data, in order to generate 30-day fatality adjustment factors for various reporting time standards, which could also shed light on the fatal injury trend over time. The major findings were as follows. Firstly, a conservative 30-day fatality adjustment factor for the first day (or 24 h) would be 1.54 (or 1.35) in an area with a large motorcycle population, like Taiwan. This produced 20-40% higher 30-day fatalities than UK Transport Research Laboratory predicted, and 15-25% higher fatalities than those in Europe/Japan. Secondly, after excluding motorcycle impacts, the Taiwanese factors suggested 8-14% higher fatalities within 30 days than those in Europe/Japan. Third, motorcycle fatalities influenced the overall 30-day fatality trend within 3 days. In the future, both the police under-reporting problem and the motorcycle/overall fatal injury pattern within 3 days after crashing in developing countries like Taiwan merit further investigation.     

A virtual reality-based system for hand function analysis

The goal of this study was to demonstrate the usability and usefulness of virtual reality technology in assessing hand functions. Ten healthy, non-disabled right-handed adult volunteers were recruited. Each volunteer used a dataglove to insert three-dimensional virtual representations of a cylinder and a prism into the target holes. To verify the reliability of the tests, each subject was retested twice. The performance testing assessed the visual-motor coordination a person needs to achieve a task accurately and within a set time. For each trial, the root mean square (RMS) value of the hand movement trajectory was projected onto the X, Y, and Z axes. This projection enabled us to measure the extent of the genuine, summative displacement of the manipulating hand. The reproducibility of the virtual reality assessment was analyzed using the intraclass correlation (ICC) approach. The total ICC values of 10 subjects demonstrated a high task completion time and RMS on the X and Z axes for the transferring of the prism. However, the values were low for the transferring of the cylinder. Because the individual coefficients of variations (CVs) varied widely in the moving of both the cylinder and the prism, the total (CVs) showed a high reading for the task completion time. Although rehabilitation clinics routinely carry out peg-moving exercises for disabled patients, our model provides a valuable quantitative real time and off-line measure of whole hand functions.