Synthesis and characterization of conjugated copolymers, and their color tuning with molecular microstructure

Poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene-co-1,4-phenylene vinylene) (MEH-R) and poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene-alt-1,4-phenylene vinylene) (MEH-A50) containing phenylene vinylene (PV) unit and alkoxyphenylene vinylene (MEHPV) unit in the main chain were synthesized by the dehydrohalogenation and Honer-Emmons reaction using potassium t-butoxide, respectively. Single layer polymer light-emitting diodes (PLEDs) were fabricated with synthesized conjugated copolymers as emitting layers, and their emission properties were compared with PPV and MEH-PPV homopolymers. UV-Visible absorption and EL spectra of MEH-Rs were blue-shifted as increasing the amount of PV unit in the main chain. Color coordinates of single layer PLEDs made with the conjugated copolymers were compared with those of standard red, green, blue, and white established by NTSC. Color coordinates of single layer PLEDs made with MEH-Rs and MEH-A50 were shifted from red (MEH-PPV) to green region (PPV) as increasing PV unit in the main chainclose1

Synthesis and characterization of conjugated copolymers, and their color tuning with molecular microstructure

Poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene-co-1,4-phenylene vinylene) (MEH-R) and poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene-alt-1,4-phenylene vinylene) (MEH-A50) containing phenylene vinylene (PV) unit and alkoxyphenylene vinylene (MEHPV) unit in the main chain were synthesized by the dehydrohalogenation and Honer-Emmons reaction using potassium t-butoxide, respectively. Single layer polymer light-emitting diodes (PLEDs) were fabricated with synthesized conjugated copolymers as emitting layers, and their emission properties were compared with PPV and MEH-PPV homopolymers. UV-Visible absorption and EL spectra of MEH-Rs were blue-shifted as increasing the amount of PV unit in the main chain. Color coordinates of single layer PLEDs made with the conjugated copolymers were compared with those of standard red, green, blue, and white established by NTSC. Color coordinates of single layer PLEDs made with MEH-Rs and MEH-A50 were shifted from red (MEH-PPV) to green region (PPV) as increasing PV unit in the main chain.1

Economic and Ecological Impacts of Adjusting the Age-Class Structure in Korean Forests: Application of Constraint on the Period-to-Period Variation in Timber Production for Long-Term Forest Management

South Korea’s successful reforestation efforts over the past 50 years have led to abundant forest resources. However, intensive reforestation during the 1970s and 1980s skewed the forests’ age distribution towards forest stands aged 30 years or older, which results in an unbalanced distribution of age-class, requiring redistribution with harvest and effective regeneration plans to produce a sustained yield of timber as well as long term ecological benefits. During this conversion process, variations in timber production can occur, causing economic and ecological risks if excessive. To prevent these likely risks, permissible levels of increase and decrease in timber production can be restricted in the planning phase. In determining the appropriate variation rate in timber production, it is necessary to understand the impacts of variation in timber production on forest management. This study performed a sensitivity analysis to evaluate the economic and ecological impacts of constraining the period-to-period variation in timber production. A multi-objective linear programming (MOLP) forest management planning model was utilized to study forests in Mt. Gari, South Korea. Nine management alternatives were set with different levels of variation rate in timber production and further constraints. The total volume and net present value (NPV) of timber production, carbon storage, and water storage were analyzed for each alternative. As timber production variation rates decreased, the amount of timber production increased and forest carbon storage decreased; furthermore, NPV diminished as variation constraints strengthened. These differences were mainly caused by selection of regeneration species according to the constraint on variation in timber production. If the variation rate was strictly restricted, the area of timber species with short rotation age increased during conversion period, in order to reduce the gap of timber production between periods. At the latter part of planning horizon, the area of broad-leaved trees was enlarged as the burden of adjusting age-class structure reduced. The appropriate variation rate in timber production was determined to be 30%, based on considerations regarding the economic and ecological impact of the variation on the forest

Preparation and Characterization of Thermally Stable Silicon-Containing Fluoropolymer Matrix for Application to Erbium-Doped Waveguide Amplifiers

This study focuses on the fabrication of fluoropolymer films as erbium(Er3+) host material with a goal of achieving sufficient thermal stability, optical clarity in the optical communication region and a chemical resistance to withstand typical fabrication processing and operation conditions. To satisfy the demands mentioned above, acrylo-polyhedral oligomeric silsesquioxane as heat-resistance improver, 2,2,3,3,4,4,5,5-octafluoropentyl acrylate as fluorinated acrylic monomer, tetrahydrofurfuryl acrylate as solubility enhancer, 3-(trimethoxysilyl)propyl methacrylate as both a silane coupling agent and another heat-resistance improver and Darocur 4265 as photoinitiator were used. Various compositions were evaluated to obtain high quantity of Er3+ ions in the polymer matrix, high thermal stability and high transparency. © 2015 Copyright © Taylor & Francis Group, LLC.1

Economic and Ecological Impacts of Adjusting the Age-Class Structure in Korean Forests: Application of Constraint on the Period-to-Period Variation in Timber Production for Long-Term Forest Management

South Korea's successful reforestation efforts over the past 50 years have led to abundant forest resources. However, intensive reforestation during the 1970s and 1980s skewed the forests' age distribution towards forest stands aged 30 years or older, which results in an unbalanced distribution of age-class, requiring redistribution with harvest and effective regeneration plans to produce a sustained yield of timber as well as long term ecological benefits. During this conversion process, variations in timber production can occur, causing economic and ecological risks if excessive. To prevent these likely risks, permissible levels of increase and decrease in timber production can be restricted in the planning phase. In determining the appropriate variation rate in timber production, it is necessary to understand the impacts of variation in timber production on forest management. This study performed a sensitivity analysis to evaluate the economic and ecological impacts of constraining the period-to-period variation in timber production. A multi-objective linear programming (MOLP) forest management planning model was utilized to study forests in Mt. Gari, South Korea. Nine management alternatives were set with different levels of variation rate in timber production and further constraints. The total volume and net present value (NPV) of timber production, carbon storage, and water storage were analyzed for each alternative. As timber production variation rates decreased, the amount of timber production increased and forest carbon storage decreased; furthermore, NPV diminished as variation constraints strengthened. These differences were mainly caused by selection of regeneration species according to the constraint on variation in timber production. If the variation rate was strictly restricted, the area of timber species with short rotation age increased during conversion period, in order to reduce the gap of timber production between periods. At the latter part of planning horizon, the area of broad-leaved trees was enlarged as the burden of adjusting age-class structure reduced. The appropriate variation rate in timber production was determined to be 30%, based on considerations regarding the economic and ecological impact of the variation on the forest.Y

Synthesis and photoluminescent properties of red phosphorescent random copolymers with photopatternable moiety

Two types of photopatternable blue emitting random copolymers, poly(VK-ran-CEMA) (1) and poly(VK-ran-CEMA-ran-MAE) (2), containing UV curable cinnamoyl moieties capable of generating negative type patterned images were synthesized and characterized. In addition, their potential possibility to be used as a photopatternable polymeric host matrix for a red phosphorescent dopant was studied by using UV-Visible absorption and PL emission spectroscopy. The λmax,PL value of poly(VK-ran-CEMA) (1) doped with a red phosphorescent dopant, (bsn)2Ir(acac), was shifted from 343 nm of poly(VK-ran-CEMA) (1) to 610 nm, with increasing the content of (bsn)2Ir(acac). Poly(VK-ran-CEMA-ran-(bsn) 2IrMAE) (3), prepared by the reaction of [(bsn)2IrCl]2 with poly(VK-ran-CEMA- ran-MAE) (2), exhibited max,PL at 610 nm in the range of red emission. These results implied efficient energy transfer from photopatternable blue emitting random copolymers to a red phosphorescent dopant. It was also found upon UV exposure on the synthesized copolymers that negative patterned images with high resolution were produced by standard photolithographic process.1

Skin Lesion Classification Using Hybrid Convolutional Neural Network with Edge, Color, and Texture Information

Herein, a new paradigm based on deep learning was proposed that allows the extraction of fine-grained differences between skin lesions in pixel units for high accuracy classification of skin lesions. As basic feature information for a dermoscopic image of a skin region, 50 different features were extracted based on the edge, color, and texture features of the skin lesion image. For the edge features, a line-segment-type analysis algorithm was used, wherein the visual information of a dermoscopic image was precisely analyzed in terms of the units of pixels and was transformed into a structured pattern. Regarding the color features of skin lesions, the dermoscopic image was transformed into multiple color models, and the features were acquired by analyzing histograms showing information regarding the distribution of pixel intensities. Subsequently, texture features were extracted by applying the well-known Law’s texture energy measure algorithm. Feature data (50 × 256) generated via the feature extraction process above were used to classify skin lesions via a one-dimensional (1D) convolution layer-based classification model. Because the architecture of the designed model comprises parallel 1D convolution layers, fine-grained features of the dermoscopic image can be identified using different parameters. To evaluate the performance of the proposed method, datasets from the 2017 and 2018 International Skin Imaging Collaboration were used. A comparison of results yielded by well-known classification models and other models reported in the literature show the superiority of the proposed model. Additionally, the proposed method achieves an accuracy exceeding 88%

Fabrication of electrophoretic display panel using prepatterned barrier rib

Fabrication process of electrophoretic display panels was investigated by ulilizing transparent soft mold press, which enables to guide uniform packing of charged TiO2 particles and colored particles for color e-Paper display. For this process, transparent soft mold was prepared by reacting silicone solution (silicone prepolymer/curing agent = 10/1 wt./wt.) into the base mold. While pressed with the transparent soft mold under 1.5 similar to 3.0 Kg(f)/cm(2) of pressure at 60 similar to 90degreesC, the photosensitive film was exposed to UV light at 865 nm in the range of 800 similar to 2,000 mJ/cm(2). The transparant soft mold was demolded by rolling up to give electrophoretic display panels with precise geometry. The process of obtaining colored electrophoretic display was also discussedclose1