T-shaped Pattern Research Articles

Design of terahertz band-stop filter based on a metallic resonator on high-resistivity silicon wafer

In this paper, we present a terahertz (THz) band-stop filter realized by fabricating a metallic T-shaped resonator pattern on the high-resistivity silicon wafer. The filter exhibits two typical band-stop response characteristics depending on the incident direction of electric field with respect to the T-shaped resonator. When the long and the short arms of the T-shaped resonator were electrically polarized by changing the incident THz wave transmission directions, the corresponding central frequencies of the band-stop filter were found to be 0.436 THz at −42dB and 0.610 THz at −28 dB, respectively. Using three-dimensional (3D) finite-integral time-domain simulations, the band-stop filter was designed, which can operate in the wavelength between 0.2 and 0.8 THz. Experimental verification was also performed using a free space THz time-domain spectroscopy system. The band-stop response characteristics are in good agreement with the simulation results. The interesting THz band-stop filtering properties suggest a promising application in the modern THz communication systems, THz time-domain spectroscopic imaging and THz continuous wave imaging.

Heuristic for constrained T-shape cutting patterns of rectangular pieces

T-shape patterns are often used in dividing stock plates into rectangular pieces, because they make good balance between plate cost and cutting complexity. A dividing cut separates the plate into two segments, each of which contains parallel strips, and the strip orientations of the two segments are perpendicular to each other. This paper presents a heuristic algorithm for constrained T-shape patterns, where the optimization objective is to maximize the pattern value, and the frequency of each piece type does not exceed the demand. The algorithm considers many dividing-cut positions, determines the pattern value associated to each position using a layout-generation procedure, and selects the one with the maximum pattern value as the solution. Pseudo upper bounds are used to skip some non-promising positions. The computational results show that the algorithm is fast and able to get solutions better than those of the optimal two-staged patterns in terms of material utilization.

A heuristic for constrained T-shape cutting patterns of circular items

The cutting and stamping process is often used to divide metal plate into circular items. It contains the cutting and stamping stages. A guillotine machine divides the plate into strips at the cutting stage. Each strip contains items of the same type. A press stamps out the items from the strips at the stamping stage. T-shape patterns are often used at the cutting stage. A cut divides a T-shape pattern into an X-segment of horizontal strips and a Y-segment of vertical strips. The position of the dividing cut should be determined such that the pattern value is maximized. A heuristic for constrained T-shape patterns is presented. For each position of the dividing cut, it generates an optimal strip layout on the Y-segment using all items, and generates another optimal strip layout on the X-segment using the remaining items. Computational results indicate that the algorithm is efficient in improving material utilization.

Patterns of Gold Nanoparticles Formed at the Air/Water Interface: Effects of Capping Agents

Gold nanoparticles stabilized with different capping agents were synthesized in a two-phase liquid-liquid system and found to self-assemble into various patterns at the air/water interface. The shapes of the patterns are closely related to the molecule structures of the capping agents. Systems with mixed capping agents were also investigated, and honeycomb patterns can be obtained in this way. T-shape and H-shape patterns were also observed. A possible mechanism based on Marangoni-Benard convection in evaporating droplets is proposed.

Microvascular system of the lumbar dorsal root ganglia in rats. Part I: a 3D analysis with scanning electron microscopy of vascular corrosion casts

So far, the morphological features of the vascular system supplying the dorsal root ganglion (DRG) have been inferred only from microangiograms. However, in the past most of these studies lacked 3D observations. This study presents the details of the microvasculature of the lumbar DRG visualized by scanning electron microscopy of vascular corrosion casts. Wistar rats were anesthetized with intraperitoneal sodium pentobarbital. After thoracotomy, the vascular system was perfused with heparinized saline, and Mercox resin was injected into the thoracic aorta. After polymerization of the resin, the vascular casts were macerated with potassium hydroxide, washed with water, and dried. The casts were examined with a scanning electron microscope. The vascular cast of the DRG was observed to have a higher density of vessels than the nerve root. Bifurcation or anastomoses of capillaries took place at approximately right angles, in a T-shaped pattern. Within the DRG, both the arterial supply and the capillary network contained blood flow control structures (ring-shaped constrictions in the cast probably representing a vascular sphincter in the microvessel). Three types of vessels could be distinguished: tortuous, straight, and bead-like capillaries. The dilations, bulges, and tortuousness of capillaries could serve the function of locally increasing the capillary surface area in a sensory neuron. The results of this study suggest a causal relationship between the metabolic demands of local neuronal activity and both the density of the capillary network and the placement of the blood flow control structures.

고효율 플라즈마 디스플레이 패널을 위한 T-형 ITO 전극의 레이저 직접 패터닝시 레이저 스캔 속도의 영향

Laser direct patterning is one of new methods which are able to replace a conventional photolithography. In order reduce the fabrication cost and to improve the luminous efficiency of AC plasma display panels (PDPs), in this experiment, a Q-switched Nd:<TEX>$YVO_4$</TEX> laser was used to fabricate T-shaped indium tin oxide (ITO) display electrodes. For the laser beam scanning speed from 100 mm/sec to 800 mm/sec, T-shaped ITO patterns were clearly obtained and investigated. The experimental results showed that the optimized T-shaped ITO electrode was obtained when the lasers scanning speed was 300 mm/s.

Herringbone array of hydrogen-bonded ribbons in 2-ethoxybenzamide from high-resolution X-ray powder diffraction

In 2-ethoxybenzamide, C(9)H(11)NO(2), the amide substituents are linked into centrosymmetric head-to-head hydrogen-bonded dimers. Additional hydrogen bonds between adjacent dimers give rise to ribbon-like packing motifs, which extend along the c axis and possess a third dimension caused by twisting of the 2-ethoxyphenyl substituent with respect to the hydrogen-bonded amide groups. The ribbons are arranged in a T-shaped herringbone pattern and cohesion between them is achieved by van der Waals forces.

An Unusual Case of Cocaine-Induced Maculopathy

Cocaine is one of the most common substances of abuse. When used intranasally, cocaine is cut with a variety of agents, which may increase local and systemic toxic reactions. We examined a 34-year-old man who complained of color disturbance. The patient reported a 10-year history of daily intranasal cocaine use, but denied use during the last year. Color vision testing showed a dysregulation of blue -yellow color vision. Electroretinogram revealed significantly reduced blue cone responses. Dilated fundus examination of both eyes revealed a bilateral maculopathy. Fluorescein angiography disclosed an early hyperfluorescence in both foveal areas which maintained in late phase. Optical coherence tomography was normal in both eyes. The patient was diagnosed with an unusual maculopathy related to a long-term intranasal cocaine use. All 6 eyes exhibited pigmentary changes located along the border of the staphyloma, and also radially to it, giving a particular T-shaped pattern of pigmentary changes. These changes were visible as either a linear strip or a triangular or oval-shaped area. Three eyes had a documented history of subretinal leakage that mimicked central serous chorioretinopathy, a well-known complication of tilted disk syndrome. Ocular complications from topical cocaine abuse are rare. Impaired color vision, as in our patient, has been reported in cocaine-withdrawn patients. To our knowledge, this is the first described case of a bilateral and symmetric maculopathy associated with long-term intranasal cocaine use. To avoid a delay of treatment, ophthalmologists should be aware that a maculopathy with small defects in color vision may be related to adulterants added to cocaine when it is used intranasally.

T-Shaped Pigmentary Changes in Tilted Disk Syndrome

Many complications associated with tilted disk syndrome may occur in the area bordering on the inferior staphyloma, including macular pigmentary changes, choroidal neovascularization, macular serous retinal detachment, polypoidal choroidal vascular anomalies, and radially orientated chorioretinal folds. The purpose of the present article is to describe an additional complication, T-shaped pigmentary changes, orientated radially from the border of the inferior staphyloma, in eyes with tilted disk syndrome. Retrospective series of 6 eyes of 6 patients (3 men and 3 women) aged from 35 to 67 years. All eyes were studied by fluorescein angiography. All 6 eyes exhibited pigmentary changes located along the border of the staphyloma, and also radially to it, giving a particular T-shaped pattern of pigmentary changes. These changes were visible as either a linear strip or a triangular or oval-shaped area. Three eyes had a documented history of subretinal leakage that mimicked central serous chorioretinopathy, a well-known complication of tilted disk syndrome. T-shaped pigmentary changes may develop in the course of tilted disk syndrome, and should be added to the list of this syndrome's possible retinal complications. These changes may indicate the presence of chronic leakage in the area around the superior border of the inferior staphyloma.

Vasomotion of Intraradicular Microvessels in Rat

This study is to investigate the changes of vasomotion of intraradicular microvessels in vivo. We have observed microvascular corrosion casts of the lumbar nerve root by scanning electron microscopy and used an immunohistochemical technique to investigate the presence and distribution of autonomic and sensory nerve in blood vessels of the nerve root. It is generally considered that the genesis of radiculopathy associated with the degenerative conditions of the spine may result from both mechanical compression and circulatory disturbance. However, the neurogenic control of intraradicular blood flow has received little attention in the past. For three-dimensional observation of intraradicular vessels, we used scanning electron microscopic examination of microvascular corrosion casts in ten Wister rats. To investigate the mechanism of vasomotion of the nerve root, we used immunohistochemical methods. The sections were incubated overnight with antisera to tyrosine hydroxylase, choline acetyl transferase, substance P, calcitonin-gene-related peptide, vasoactive intestinal peptide, somatostatin, neuropeptide Y, leucine-enkephalin, cholecystokinin octapeptide, brain-nitric oxide synthase, and endothelium-nitric oxide synthase. Abidin-biotin complex method was used as the immunohistochemical procedure and the sections were observed under the light microscope. The general view of whole vascular casts of the lumbar spinal cord and nerve roots showed a high density of vessels. Bifurcation or anastomoses of capillaries approximately took place at right angles in a T-shaped pattern and capillaries showed a lot of ring-like compressions. This ring-like compression on the cast may represent a vascular sphincter in the microvessels. This study also reveals the existence of perivascular adrenergic, cholinergic, peptidergic, and nitroxydergic innervation with a possible role in neurogenic regulation of nerve root circulation. Perivascular nerve plexuses around intraradicular microvessels suggest that the autonomic nerves play an important role in intraradicular circulation.

An algorithm for the constrained two-dimensional rectangular multiple identical large object placement problem

This paper presents an algorithm for the constrained, two-dimensional, rectangular multiple identical large object placement problem, where a set of small rectangular items must be cut from a specified number of identical plates, so as to maximize the value of the cut items. The algorithm generates optimal homogenous T-shape patterns that contain only homogenous strips. A homogenous strip contains items of the same type. A cut divides the plate into two segments. Each segment consists of strips with the same direction. The strips in the first segment are horizontal, and those in the second segment are vertical. The algorithm is based on the bottom-up tree-search approach. Both lower and upper bounds are used to prune the search tree. The computational results indicate that the algorithm is capable of solving problems of small and medium scales.

Interference effects in a group of tall buildings closely arranged in an L- or T-shaped pattern

Interference effects in five square tall buildings arranged in an L- or T-shaped pattern are investigated in the wind tunnel. Mean and fluctuating shear forces, overturning moments and torsional moment are measured on each building with a force balance mounted at its base. Results are obtained at two values of clear separation between adjacent buildings, at half and a quarter building breadth. It is found that strong interference effect exists on all member buildings, resulting in significant modifications of wind loads as compared with the isolated single building case. Sheltering effect is observed on wind loads acting along the direction of an arm of the "L" or "T" on the inner buildings. However, increase in these wind loads from the isolated single building case is found on the most upwind edge building in the arm when wind blows at a slight oblique angle to the arm. The corner formed by two arms of buildings results in some wind catchment effect leading to increased wind pressure on windward building faces. Interesting interference phenomena such as negative drag force are reported. Interference effects on wind load fluctuations, load spectra and dynamic building responses are also studied and discussed.

Etching of nanopatterns in silicon using nanopantography

Nanopantography is a technique for parallel writing of nanopatterns over large areas. A broad ion beam impinges on a substrate containing many microfabricated electrostatic lenses that focus ions to spots at the substrate surface. Here, etching of nanopatterns is demonstrated. The substrate was continuously titled about x and y axes with 0.11° precision, corresponding to a translation of the ion foci of 1.5nm on the substrate. With tilting in one direction, 15nm full width at half maximum trenches 45nm deep were etched into a Si wafer using an Ar+ beam in a Cl2 ambient. T-shaped patterns were etched by tilting the substrates in two directions.

Potential of phase-shifted optical proximity correction for 65nm T-shaped pattern in high numerical aperture lithography

Optical proximity correction (OPC) has been employed as a key enabling resolution enhancement technique required to meet image size control requirements imposed by state-of-the-art integrated circuit product programs. However, at the sub-65-nm node, the line end shortening effect for T-shaped pattern becomes pronounced and it is hard to correct using OPC due to the small gap size. Phase shift masks (PSMs) can improve lithography resolution and will be used at 65nm node. However, phase conflicts occur when imaging a T-shaped pattern with PSM. Hence, it is becoming increasingly more challenging to print T-shaped patterns for sub-65-nm nodes. A new OPC method, phase-shifted optical proximity correction (PSOPC), has been proposed to improve the imaging fidelity for T-shaped pattern and avoid the phase conflict caused by the use of PSM. A PSOPC mask has phase-shifted segments that can simultaneously modify the intensity and phase of the incident light. PROLITH 9.0 and in-house-software microcruiser were applied to demonstrate the new approach of PSOPC. The authors’ results show that the line end shortening can be reduced to 4.6nm and the depth of focus can be improved to over 200nm. These results showed that PSOPC has significant potential as a new resolution enhancement technology for 65nm T-shaped pattern lithography.

T-shape homogenous block patterns for the two-dimensional cutting problem

This paper presents an algorithm for unconstrained T-shape homogenous block cutting patterns of rectangular pieces. A vertical cut divides the stock sheet into two segments. Each segment consists of sections that have the same length and direction. A section contains a row of homogenous blocks. A homogenous block consists of homogenous strips of the same piece type. Each cut on the block produces just one strip. The directions of two strips cut successively from a block are either parallel or orthogonal. The algorithm uses a dynamic programming recursion to generate optimal blocks, solves knapsack problems to obtain the block layouts on the sections and the section layout on segments of various lengths, and optimally selects two segments to compose the cutting pattern. The computational results indicate that the algorithm is efficient in improving material usage, and the computation time is reasonable.

A recursive algorithm for generating homogeneous T-shape cutting patterns

Both the material utilization and the complexity of the cutting process should be considered when generating cutting patterns. This paper presents a recursive algorithm for constrained two-dimensional guillotine-cutting problems of rectangles. It uses homogeneous T-shape patterns to simplify the cutting process. Only homogeneous strips are allowed, each of which contains rectangular items of the same type. The plate is divided into two segments, each of which consists of strips with the same length and direction. The strip directions of the two segments are perpendicular to each other. Two recursion functions are established. The first generates optimal layouts of parallel strips on segments with specified sizes, and the second determines the optimal T-shape pattern on the plate. The optimal solution to the unconstrained version of the cutting problem is used to reduce the computation time. The computational results indicate that the algorithm is efficient both in computation time and in material utilization.

Asymmetry of aerial image after mask pattern correction for off-axis incident light in extreme ultraviolet lithography

In extreme-ultraviolet lithography (EUVL), asymmetry in printed images arises from the off-axis incidence of light illuminating the mask and from the thicknesses of the absorber and buffer layers of the mask. This study examined whether or not the asymmetry of printed images due to off-axis incidence affected pattern edge position error. The pattern edge position error and asymmetry of printed images were investigated using two types of patterns with a critical dimension (CD) of 44nm: nested lines, because they induce asymmetry in the printed image for off-axis incidence even though the mask layout is perfectly symmetrical and T-shaped patterns. The amount of pattern edge position error was found to be almost the same for off-axis and normal incidence, irrespective of the larger asymmetry in the printed image for off-axis incidence, even for thick absorber and buffer layers.

An exact algorithm for generating homogenous T-shape cutting patterns

Both the material usage and the complexity of the cutting process should be considered in generating cutting patterns. This paper presents an exact algorithm for constrained two-dimensional guillotine-cutting problems of rectangles. It uses homogenous T-shape patterns to simplify the cutting process. Only homogenous strips are allowed, each of which contains rectangular blanks of the same size and direction. The sheet is divided into two segments. Each segment consists of strips of the same length and direction. The strip directions of the two segments are perpendicular to each other. The algorithm is based on branch and bound procedure combined with dynamic programming techniques. It is a bottom-up tree-search approach that searches the solution tree from the branches to the root. Tighter bounds are established to shorten the searching space. The computational results indicate that the algorithm is efficient both in computation time and in material usage.

New CPW low‐pass filter based on a slow wave structure

AbstractA new periodic loaded coplanar waveguide (CPW) low‐pass filter with very sharp cutoff has been designed and fabricated. The device consists of a CPW structure with T‐shaped periodic patterns on both the central strip and ground planes. With such a design, capacitive coupling is added between the signal strip and ground planes at periodic positions, resulting in a filtering action and slow‐wave effect. In addition to a sharp cutoff, the device exhibits very low insertion loss in the pass band, wide rejection bandwidth, and simple design and fabrication. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 190–193, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11011

Pattern printability for off-axis incident light in extreme ultraviolet lithography

Off-axis incident light produces shadowing and an imbalance in the diffracted light. Shadowing causes a change in the critical dimension (CD) and a shift in the position of patterns due to the multiple interference of the absorber and buffer layers. In addition, the imbalance in the diffracted light influences the optical proximity-effect correction (OPC) of actual patterns with a process factor k1 below 0.6. In this study, the main factors influencing OPC were investigated. These include asymmetric aberrations and optical proximity effects (OPE) in line patterns. OPC was then applied to a T-shaped pattern. It is found that the mask error factor (MEF) in low-contrast regions of a layout is an important consideration in OPC.