Dipyrenylpyridines for electron-transporting materials in organic light emitting devices and their structural effect on electron injection from LiF/Al cathode

3,5-Dipyrenylpyridine (PY1) and 2,6-dipyrenylpyridine (PY2) were synthesized to achieve not only efficient electron injection from cathode but also high electron mobility. The both of compounds showed much higher electron mobilities than that of Alq₃, and have a similar ionization potential and electron affinity. However, the barrier height of electron injection from cathode to PY1 in an organic light emitting device was much smaller than that to PY2, probably due to the steric hindrance to the central pyridine group. These results suggest that the chemical affinity of electron-transporting materials with cathode is more important than their own electron affinity to improve the electron injection.     

An optimization of tungsten plug chemical mechanical polishing (CMP) using different consumables

The continuous shrinkage of integrated circuit devices provides the advantage of having more electrical functions on the smaller chips. However, it has posed severe challenges to the manufacturing of these products. In patterning steps, the depth of focus becomes small, due to the nature of patterning small features and is aggravated by the presence of step height differences in the exposure field. When the aspect ratio of holes increases, aluminum, which has been the choice of metal to fill holes, no longer effectively fills small holes. On some occasions, discontinuous aluminum exists in the holes, resulting from poor step coverage. Tungsten (W), on the other hand, can satisfactorily fill small holes by chemical vapor deposition and thus fills a need to replace aluminum as an electrical connector plug for layers separated by this plug. Chemical mechanical polish (CMP) has been used recently to planarize substrates and improve the depth of focus, as in the case of hole patterning. It is also used to prepare the metal plug effectively. CMP processing involves various parameters, such as machine configuration, slurry chemistry and formulation, polishing pad configuration, pad hardness, etc. Although the mechanism is not fully understood, these parameters are known to significantly influence the degree of planarization, contamination, defects, etc. In this paper we explore the effects of consumables used in the W-CMP process on the control of several problems, such as recessed plug, dishing and oxide erosion, etc. Based on our findings, we implement a two-step W-CMP process to improve the qualities of the polished wafers. The first step involves a proper combination of slurry and pad to polish most of the bulk tungsten with a high polish rate. The second step uses the same pad, slurry and a proprietary additive to slowly polish the remaining tungsten. In this way, we are able to obtain a workable W-CMP process. © 2001 Kluwer Academic Publishers     

产生淀粉糖化酶菌株的诱变选育

以黑曲霉vin-1为研究对象，通过紫外诱变（UV）和硫酸二乙酯（DES）两次诱变，获得产酶较高的菌株vin-1-24-72，酶活达到527u／g，比原始菌株提高154％，RDA％值为40％。菌株经过7次传代，酶活较稳定。     

VLSI array algorithms and architectures for RSA modularmultiplication

We present two novel iterative algorithms and their array structures for integer modular multiplication. The algorithms are designed for Rivest-Shamir-Adelman (RSA) cryptography and are based on the familiar iterative Horner's rule, but use precalculated complements of the modulus. The problem of deciding which multiples of the modulus to subtract in intermediate iteration stages has been simplified using simple look-up of precalculated complement numbers, thus allowing a finer-grain pipeline. Both algorithms use a carry save adder scheme with module reduction performed on each intermediate partial product which results in an output in carry-save format. Regularity and local connections make both algorithms suitable for high-performance array implementation in FPGA's or deep submicron VLSI. The processing nodes consist of just one or two full adders and a simple multiplexor. The stored complement numbers need to be precalculated only when the modulus is changed, thus not affecting the performance of the main computation. In both cases, there exists a bit-level systolic schedule, which means the array can be fully pipelined for high performance and can also easily be mapped to linear arrays for various space/time tradeoffs     

Correlation analysis between pattern and non-pattern wafer for characterization of shallow trench isolation–chemical–mechanical polishing (STI–CMP) process

This study is about control of oxide removal amounts on the shallow trench isolation (STI) patterned wafers using removal rate and thickness of blanket (non-patterned) wafers. At first, the removal properties of plasma enhanced tetra-ethyl ortho-silicate (PETEOS) blanket wafers was investigated, and then it was compared with the removal properties and the planarization (step height) as a function of polishing time of the specific STI patterned wafers. We found that there is a relationship between the amount of oxide removal by blanket and patterned wafers. We analyzed this relationship, and the post-CMP thickness of patterned wafers could be controlled by removal rate and removal target thickness of blanket wafers. As the result of correlation analysis, we confirmed that there was the strong correlation between patterned and blanket wafers (correlation factor: 0.7109). So, we could confirm the repeatability as applying to STI CMP process from the linear formula obtained.     

Evaluation of the Effects of Developmental Trauma on Neurotransmitter Systems Using Functional Molecular Imaging

Early life stress (ELS) is strongly associated with psychiatric disorders such as anxiety, depression, and schizophrenia in adulthood. To date, biological, behavioral, and structural aspects of ELS have been studied extensively, but their functional effects remain unclear. Here, we examined NeuroPET studies of dopaminergic, glutamatergic, and serotonergic systems in ELS animal models. Maternal separation and restraint stress were used to generate single or complex developmental trauma. Body weights of animals exposed to single trauma were similar to those of control animals; however, animals exposed to complex trauma exhibited loss of body weight when compared to controls. In behavioral tests, the complex developmental trauma group exhibited a decrease in time spent in the open arm of the elevated plus-maze and an increase in immobility time in the forced swim test when compared to control animals. In NeuroPET studies, the complex trauma group displayed a reduction in brain uptake values when compared to single trauma and control groups. Of neurotransmitter systems analyzed, the rate of decrease in brain uptake was the highest in the serotonergic group. Collectively, our results indicate that developmental trauma events induce behavioral deficits, including anxiety- and depressive-like phenotypes and dysfunction in neurotransmitter systems.     

Modeling dynamic developable meshes by the Hamilton principle

In this paper, a new dynamic developable surface model is proposed. The proposed model represents developable surfaces using triangle meshes. A novel algorithm is proposed to introduce the Hamilton principle into these meshes such that the resulting developable model is dynamic, i.e., it can offer a time-dependent continuous path to deform the model. Applications with examples are presented; these show that the proposed technique can model buckled developable surfaces well, and can offer physically-realistic animations of deformed developable surfaces.     

Handling degenerate cases in exact geodesic computation on triangle meshes

The computation of exact geodesics on triangle meshes is a widely used operation in computer-aided design and computer graphics. Practical algorithms for computing such exact geodesics have been recently proposed by Surazhsky et al. [5]. By applying these geometric algorithms to real-world data, degenerate cases frequently appear. In this paper we classify and enumerate all the degenerate cases in a systematic way. Based on the classification, we present solutions to handle all the degenerate cases consistently and correctly. The common users may find the present techniques useful when they implement a robust code of computing exact geodesic paths on meshes.     

Scalable network electrical devices using ZnO nanowalls

We report the fabrication and electrical characteristics of scalable nanowall network devices and their gas sensor applications. For the network device fabrications, two-dimensional ZnO nanowall networks were grown on AlN/Si substrates with a patterned SiO(2) mask layer using selective-area metal-organic vapor-phase epitaxy. The ZnO nanowalls with c-axis orientation were heteroepitaxially grown on AlN/Si substrates, and were single-crystalline, as determined by x-ray diffraction and transmission electron microscopy. The electrical conductivity of the nanowall networks was measured as a function of nanowall dimensions. The conductance increased linearly with the channel width for widths larger than 1 μm, but saturated at 36 μS for widths below 1 μm. This conductance scaling behavior is explained by enhanced conduction through the regions near the edge of the patterned growth areas, where the density of the networks was higher. Gas sensor applications were investigated using the nanowall network devices, and highly sensitive gas detection was demonstrated.     

Fabrication of nano-structured SPR chip for sensitivity enhancement

We used the Langmuir-Blodgett (LB) method for preparation of large area, defect-free monolayer silica particle film as a template for the fabrication of nano-structure Au pattern on a conventional Au substrate for Surface Plasmon Resonance (SPR). Well organized, trigonal pyramid shaped Au nano-structures were able to construct on 34 separate chips in one fabrication process. The dimensions of trigonal pyramid nano-structures were precisely controlled by changing the particle size of the silica LB template. The nano-structure Au patterned SPR chips provides the enhancement of sensitivity in SPR analysis. The sensitivity enhancement of nano-structure patterned chips was evaluated by comparison with conventional flat Au chips. The nano-structure patterned substrate demonstrated a sensitivity enhancement up to 120% compared to a conventional SPR chip when ethanol solution was used as an analyte.