Metastable Copper‐Phthalocyanine Single‐Crystal Nanowires and Their Use in Fabricating High‐Performance Field‐Effect Transistors

This paper describes a simple, vapor‐phase route for the synthesis of metastable α‐phase copper‐phthalocyanine (CuPc) single‐crystal nanowires through control of the growth temperature. The influence of the growth temperature on the crystal structures, morphology, and size of the CuPc nanostructures is explored using X‐ray diffraction (XRD), optical absorption, and transmission electron microscopy (TEM). α‐CuPc nanowires are successfully incorporated as active semiconductors in field‐effect transistors (FETs). Single nanowire devices exhibit carrier mobilities and current on/off ratios as high as 0.4 cm² V^?1 s^?1 and >10⁴, respectively.     

Analysis of the Signal of Singing Using the Vibrato Parameter in the Context of Choir Singers

Evaluation of quality of singing is an issue subjectively realized by the experts. This paper presents the results of the analysis of the vibrato parameter in the singing. The well-known fact is the existence of vibrato of sufficient quality in the voices of professional singers. The authors focus here on the choral voices to assess the quality of their singing from the point of view of the vibrato parameter. The method presented here is developed to evaluate the vibrato while singing under conditions close to the real ones. The study was carried out on the recordings of the members of an academic choir. As a result of tests it was found that not all singers present the same quality of vibrato in terms of deviation of vibrato confidence （STDCV）.     

Performance of large-size superconducting coil in 0.21T MRI system

A high-temperature superconductor (HTS) was used on magnetic resonance imaging (MRI) receiver coils to improve image quality because of its intrinsic low electrical resistivity. Typical HTS coils are surface coils made of HTS thin-film wafers. Their applications are severely limited by the field of view (FOV) of the surface coil configuration, and the improvement in image quality by HTS coil is also reduced as the ratio of sample noise to coil noise increases. Therefore, previous HTS coils are usually used to image small in vitro samples, small animals, or peripheral human anatomies. We used large-size HTS coils (2.5-, 3.5-, and 5.5-in mean diameter) to enhance the FOV and we evaluated their performance through phantom and human MR images. Comparisons were made among HTS surface coils, copper surface coils, and cool copper surface coils in terms of the signal-to-noise ratio (SNR) and sensitivity profile of the images. A theoretical model prediction was also used to compare against the experimental result. We then selected several human body parts, including the wrist, feet, and head, to illustrate the advantage of HTS coil over copper coil when used in human imaging. The results show an SNR gain of 200% for 5.5-in HTS coil versus same size copper coils, while for 2.5- and 3.5-in coils it is 250%. We also address the various factors that affect the performance of large size HTS coils, including the coil-to-sample spacing due to cryogenic probe and the coil-loading effect.     

Adhesion and Surface Interactions of a Self‐Healing Polymer with Multiple Hydrogen‐Bonding Groups

The surface properties and self‐adhesion mechanism of self‐healing poly(butyl acrylate) (PBA) copolymers containing comonomers with 2‐ureido‐4[1H]‐pyrimidinone quadruple hydrogen bonding groups (UPy) are investigated using a surface forces apparatus (SFA) coupled with a top‐view optical microscope. The surface energies of PBA–UPy4.0 and PBA–UPy7.2 (with mole percentages of UPy 4.0% and 7.2%, respectively) are estimated to be 45–56 mJ m^?2 under dry condition by contact angle measurements using a three probe liquid method and also by contact and adhesion mechanics tests, as compared to the reported literature value of 31–34 mJ m^?2 for PBA, an increase that is attributed to the strong UPy–UPy H‐bonding interactions. The adhesion strengths of PBA–UPy polymers depend on the UPy content, contact time, temperature and humidity level. Fractured PBA–UPy films can fully recover their self‐adhesion strength to 40, 81, and 100% in 10 s, 3 h, and 50 h, respectively, under almost zero external load. The fracture patterns (i.e., viscous fingers and highly “self‐organized” parallel stripe patterns) have implications for fabricating patterned surfaces in materials science and nanotechnology. These results provide new insights into the fundamental understanding of adhesive mechanisms of multiple hydrogen‐bonding polymers and development of novel self‐healing and stimuli‐responsive materials.     

Study of the breakdown failure mechanisms for power AlGaN/GaN HEMTs implemented using a RF compatible process

The breakdown failure mechanisms for a family of power AlGaN/GaN HEMTs were studied. These devices were fabricated using a commercially available MMIC/RF technology with a semi-insulating SiC substrate. After a 10 min thermal annealing at 425 K, the transistors were subjected to temperature dependent electrical characteristics measurement. Breakdown degradation with a negative temperature coefficient of ?0.113 V/K for the devices without field plate was found. The breakdown voltage is also found to be a decreasing function of the gate length. Gate current increases simultaneously with the drain current during the drain-voltage stress test. This suggests that the probability of a direct leakage current path from gate to the 2-DEG region. The leakage current is attributed by a combination of native and generated traps/defects dominated gate tunneling, and hot electrons injected from the gate to channel. Devices with field plate show an improvement in breakdown voltage from ～40 V (with no field plate) to 138 V and with lower negative temperature coefficient. A temperature coefficient of ?0.065 V/K was observed for devices with a field plate length of 1.6 μm.     

Fabrication and electrical properties of laser-shaped thick-film and LTCC microresistors

The dimensions of discrete passives, passive integrated components (arrays, networks) and embedded integral ones should be reduced significantly in the nearest future. Therefore the relations between technological accuracy and limitations, minimal geometrical dimensions and electrical as well as stability properties become more and more important. This paper presents systematic studies of thick-film or LTCC microresistors made with the aid of laser shaping. The investigations are concerned with miniaturization of two resistor dimensions, namely length (down to 30 μm) and width (also down to 30 μm). The sheet resistance, hot temperature coefficient of resistance (HTCR) as well as long-term stability and durability of test structures to various short electrical pulses were related to geometrical properties of microresistors. Such investigations proved that combining of current materials and fabrication methods used in modern thick-film and LTCC technologies with laser shaping made possible fabrication of 30 × 30 μm² microresistors with satisfactory electrical properties and can serve as interesting alternative for thick-film and LTCC resistors miniaturization.     

Graphical-Model-based Morphometric Analysis

We propose a novel method for voxel-based morphometry (VBM), which we call Graphical-Model-based Morphometric Analysis (GAMMA), to identify morphological abnormalities automatically, and to find complex probabilistic associations among voxels in magnetic-resonance images and clinical variables. GAMMA is a fully automatic, nonparametric morphometric-analysis algorithm, with high sensitivity and specificity. It uses a Bayesian network to represent the associations among voxels and the function variable, and uses a contextual-clustering method based on a Markov random field to find clusters in which all voxels have similar associations with the function variable. We use loopy belief propagation to infer the unobserved label field and belief map. As opposed to voxel-based morphometric methods based on general linear models, GAMMA is capable of identifying nonlinear associations among the function variable and voxels. Compared with our previous approach, a Bayesian morphometry algorithm, GAMMA has greater sensitivity, specificity, and computational efficiency.     

Scattering Properties of Cylindrical Ferrite Posts and Their Applications

The scattering field of a ferrite post and a cylindrical ferrite post containing conducting post illuminated by a plane wave is analyzed. The special interest is the scattering property of the ferrite posts, which is resonating at certain modes such as TM₁₁ mode. We hope to know the speciality it shows and find its applications. It is found that the scattering field pattern of a resonating ferrite post is similar to the rotation of the scattering field pattern of a dielectric cylindrical post, which has the same dimension as ferrite. The scattering properties of the ferrite may give us some inspirations to explore its applications in microwave components. This property is utilized to explain the mechanism of the operation of the circulators. It also may be used in microstrip patch antenna, coupler and filter to control their properties. Other applications may be possible too. Some calculation results are presented.     

A comprehensive multimodal eye recognition

Iris recognition is tested to be one of the most reliable approaches for automatic personal recognition under the infrared light. However, it is challenging and difficult to acquire good quality iris patterns of dark color eyes in the visible wavelengths. Sclera recognition can achieve good recognition accuracy in the visible spectrum, but the performance will drop when the sclera pattern is saturated. In this paper, we proposed a comprehensive multimodal eye recognition system that uses both iris and sclera patterns for recognition from the same eye image. The experimental results show that the proposed multimodal frontal eye recognition method can achieve better recognition accuracy than unimodal iris or sclera recognition. In addition, we propose a multimodal multi-angle eye recognition system that can further improve the recognition accuracy.     

Altruism on American Television: Examining the Amount of, and Context Surrounding, Acts of Helping and Sharing

Using a representative sample of television content featuring 2,227 programs across different genres and 18 different channels, the frequency and context of altruistic actions were content analyzed. A social cognitive theory approach was taken to guide the selection of contextual variables. The results showed that 73% of the programs in the sample featured instances of helping/sharing at a rate of 2.92 incidents per hour. Further, the actions were most likely to be initiated by adult White males and many acts were depicted in a humorous, realistic, and rewarding context. In terms of channel differences, shows on children's basic cable featured not only the highest proportion of programs with one or more instances of altruism but also the highest rate per hour (4.02 acts). Differences in contextual features and channel type are discussed in terms of social cognitive theory below.