Influence of UV Polymerization Curing Conditions on Performance of Acrylic Pressure Sensitive Adhesives.

Acrylic pressure sensitive adhesives (PSAs) were prepared by UV polymerization under varying curing conditions of both fast and slow curing, employing high- and low-intensity UV radiation, respectively. The influences of curing conditions and isobornyl acrylate (IBOA) content on PSA performance were comprehensively investigated by measurement of their rheological, thermal, and adhesive properties. In particular, rheological characterization was accomplished by several analytical methods, such as in situ UV rheology, frequency sweep, stress relaxation, and temperature ramp tests, to understand the effect of the UV curing process and IBOA content on the viscoelastic behavior of acrylic PSAs. The slow-cured samples were observed to form more tightly crosslinked networks compared to the fast-cured. On the other hand, at high loading levels of IBOA, in the case of slow curing, the sample exhibited a contrasting trend, having the shortest stress relaxation time and the highest energy dissipation; this was due to molecular chain scission occurring in the crosslinked polymer during UV polymerization. Consequently, we successfully demonstrated the influence of monomer composition of acrylic PSAs, and that of curing conditions employed in UV polymerization. This study provides valuable insights for the development of crosslinked polymer networks of acrylic PSAs for flexible display applications.

Transparent, Water-Repellent, Antiviral, Antistatic, and Flexible Cu-Plasma-Polymerized Fluorocarbon Nanocomposite Thin Films.

Polymer thin films containing fluorine are attracting much attention in various high-tech industries owing to their transparency, flexibility, and excellent water repellency. However, the generation of static electricity due to high electrical resistance limits their application. In this study, highly transparent and flexible Cu-plasma-polymerized fluorocarbon (PPFC) nanocomposite thin films that exhibit hydrophobicity and antistatic properties are proposed. These films, obtained using the mid-range frequency sputtering, exhibited a light transmittance of 84.2%, a water contact angle of 94.6°, and a sheet resistance of 1.2 × 1012 Ω/□. Transmission electron microscopy and small angle X-ray scattering confirmed that Cu nanoparticles with an average size of 4-5 nm were distributed uniformly in the PPFC matrix. In repeated fatigue bending tests, the Cu-PPFC nanocomposite thin films exhibited excellent mechanical robustness and flexibility. Antiviral properties of the Cu-PPFC nanocomposite thin films were evaluated against influenza A virus, and the number decreased by 96.9% after 30 min. Carbon nanotube-Cu-polytetrafluoroethylene composite targets are advantageous for large-area coating and mass production because they can be applied in large-area sputtering and roll-to-roll processes. The transparency, charging characteristics, and water repellency can be easily controlled in Cu-PPFC nanocomposite thin films by controlling the sputtering power density according to the required product. Therefore, these films can be applied in various industries such as flexible displays, medical, automobiles, functional textiles, and aerospace.

Effects of carbon concentration on high-hardness plasma-polymer-fluorocarbon film deposited by mid-range frequency sputtering.

We propose a method for fabricating high-hardness plasma-polymer-fluorocarbon (PPFC) thin films with controllable optical and surface properties via manipulation of the target composition design and sputtering power density. The carbon/polytetrafluoroethylene (PTFE) composite polymeric material targets with the low electrical resistance were prepared by press-molding using a mechanically mixed powder of PTFE, carbon nanotubes, and graphite. The composite targets showed electrical sheet resistances of 0.1-100 Ω/sq. PPFC thin films were deposited by mid-range frequency (MF) sputtering at power densities within 0.62~4.92 W/cm2. The maximum surface hardness of the PPFC thin film was 4.75 GPa, which was 21.6 times higher than that of fluorocarbon thin film sputtered from PTFE under the same conditions. With the increase of the carbon concentration in the target, the carbon cross-linking density of the PPFC thin film increased but the fluorine concentration decreased. The concentration of fluorine in the PPFC thin films grew with increasing sputtering power density. The MF sputtered carbon-rich PPFC thin films are controllable with physical properties of optical transmittance, surface hardness and surface water repellency which could be applied as protective layers for transparent flexible devices.

Hollow hybrid spheres with silica inner shell for non-deformable, core exchangeable properties.

Core exchangeable polymer-silica hybrid capsules with solvent-selective permeability were fabricated, in which the internal silica layer, formed from pre-included precursors, has the role of a framework to prevent irreversible deformation of the hollow capsules.

Self-Cleaning Transparent Heat Mirror with a Plasma Polymer Fluorocarbon Thin Film Fabricated by a Continuous Roll-to-Roll Sputtering Process.

This paper proposes a novel self-cleaning transparent heat mirror (SC-THM) produced by depositing a plasma polymer fluorocarbon thin film on a silver-and-SiN x multilayer structure fabricated by continuous roll-to-roll sputtering. The optimal structure and the thickness of each thin film of three-layer and five-layer SC-THMs were derived from optical simulation. In the five-layer SC-THM, the visible light transmittance was 60.67% at a wavelength of 406 nm and the infrared (IR) transmittance was 6.86% at a 1000 nm wavelength and 2.50% at a 1500 nm wavelength. The value of the performance parameter Tvis/ Tsol was 1.70. The SC-THM exhibited self-cleaning with a very good water repellency of more than 111°, achieved by applying a low-surface-energy fluorocarbon thin film to the top layer. This study successfully demonstrated the IR blocking properties of an SC-THM through IR reflection and IR irradiation experiments.

Hydrophobic and stretchable Ag nanowire network electrode passivated by a sputtered PTFE layer for self-cleaning transparent thin film heaters.

We demonstrated hydrophobic, flexible/stretchable, and transparent electrodes made up of Ag nanowire (NW) networks passivated by a sputtered polytetrafluoroethylene (PTFE) layer to produce self-cleaning transparent thin film heaters (TFHs). Using carbon nanotubes and a PTFE mixed conducting target, we successfully sputtered a transparent PTFE layer on the Ag NW network using mid-frequency magnetron sputtering. The hydrophobic surface of the PTFE/Ag NW electrodes led to water-repelling and self-cleaning transparent Ag NW electrodes, which are beneficial for transparent TFH-based smart windows. Furthermore, hydrophobic PTFE/Ag NW electrodes coated on polyethylene terephthalate (PET) and polyurethane (PU) substrates showed outstanding flexibility and stretchability, respectively, due to the capping effect of the PTFE layer. Based on outer/inner bending and stretching test results, we demonstrated the superior mechanical properties of the PTFE/Ag NW electrode compared to a bare Ag NW electrode. Finally, we investigated the feasibility of the PTFE/Ag NW film coated on a PU substrate as a transparent and stretchable electrode for stretchable and self-cleaning transparent TFHs. The effective heat generation of the stretchable PTFE/Ag NW electrode indicates the potential for energy-efficient multi-functional PTFE/Ag NW-based TFHs attached to automobile windows.

Batch and continuous culture kinetics for production of carotenoids by beta-ionone-resistant mutant of Xanthophyllomyces dendrorhous.

A beta-ionone-resistant mutant strain isolated from the red yeast Xanthophyllomyces dendrorhous KCTC 7704 was used for batch and continuous fermentation kinetic studies with glucose media in a 2.5-1 jar fermentor at 22 degrees C and pH 4.5. The kinetic pattern of growth and carotenoid concentration in the batch fermentations exhibited a so-called mixed-growth-associated product formation, possibly due to the fact that the content of intracellular carotenoids depends on the degree of physical maturation toward adulthood. To determine the maximum specific growth rate constant (microm) and Monod constant (k(s)) for the mutant, glucose-limited continuous culture studies were performed at different dilution rates within a range of 0.02-0.10 h(-1). A reciprocal plot of the steady-state data (viz., reciprocal of glucose concentration versus residence time) obtained from continuous culture experiments was used to estimate a microm of 0.15 h(-1) and k(s) of 1.19 g/l. The carotenoid content related to the residence time appeared to assume a typical form of saturation kinetics. The maximum carotenoid content (Xm) for the mutant was estimated to be 1.04 microg/mg dry cell weight, and the Lee constant (k(m)), which was tentatively defined in this work, was found to be 3.0 h.

Flexible Polymer/Metal/Polymer and Polymer/Metal/Inorganic Trilayer Transparent Conducting Thin Film Heaters with Highly Hydrophobic Surface.

Polymer/metal/polymer and polymer/metal/inorganic trilayer-structured transparent electrodes with fluorocarbon plasma polymer thin film heaters have been proposed. The polymer/metal/polymer and polymer/metal/inorganic transparent conducting thin films fabricated on a large-area flexible polymer substrate using a continuous roll-to-roll sputtering process show excellent electrical properties and visible-light transmittance. They also exhibit water-repelling surfaces to prevent wetting and to remove contamination. In addition, the adoption of a fluorocarbon/metal/fluorocarbon film permits an outer bending radius as small as 3 mm. These films have a sheet resistance of less than 5 Ω sq-1, sufficient to drive light-emitting diode circuits. The thin film heater with the fluorocarbon/Ag/SiNx structure exhibits excellent heating characteristics, with a temperature reaching 180 °C under the driving voltage of 13 V. Therefore, the proposed polymer/metal/polymer and polymer/metal/inorganic transparent conducting electrodes using polymer thin films can be applied in flexible and rollable displays as well as automobile window heaters and other devices.

Fluorocarbon Thin Films Fabricated using Carbon Nanotube/Polytetrafluoroethylene Composite Polymer Targets via Mid-Frequency Sputtering.

Carbon nanotube/polytetrafluoroethylene composite polymer targets are proposed for use in the fabrication of fluorocarbon thin films using the mid-frequency sputtering process. Fluorocarbon thin films deposited using carbon nanotube/polytetrafluoroethylene composite targets exhibit an amorphous phase with a smooth surface and show a high water contact angle, optical transmittance, and surface hardness. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy studies reveal that as the carbon nanotube concentration increased in the composite target, a carbon cross-linked structure was formed, which enhanced the film hardness and the modulus of the fluorocarbon thin film. Large-area fluorocarbon thin films with a substrate width of 700 mm were successfully fabricated by a pilot-scale roll-to-roll sputtering system using a carbon nanotube/polytetrafluoroethylene composite target.

Roll-to-Roll sputtered ITO/Cu/ITO multilayer electrode for flexible, transparent thin film heaters and electrochromic applications.

We fabricate high-performance, flexible, transparent electrochromic (EC) films and thin film heaters (TFHs) on an ITO/Cu/ITO (ICI) multilayer electrode prepared by continuous roll-to-roll (RTR) sputtering of ITO and Cu targets. The RTR-sputtered ICI multilayer on a 700 mm wide PET substrate at room temperature exhibits a sheet resistance of 11.8 Ω/square and optical transmittance of 73.9%, which are acceptable for the fabrication of flexible and transparent EC films and TFHs. The effect of the Cu interlayer thickness on the electrical and optical properties of the ICI multilayer was investigated in detail. The bending and cycling fatigue tests demonstrate that the RTR-sputtered ICI multilayer was more flexible than a single ITO film because of high strain failure of the Cu interlayer. The flexible and transparent EC films and TFHs fabricated on the ICI electrode show better performances than reference EC films and TFHs with a single ITO electrode. Therefore, the RTR-sputtered ICI multilayer is the best substitute for the conventional ITO film electrode in order to realize flexible, transparent, cost-effective and large-area EC devices and TFHs that can be used as flexible and smart windows.

Association between tumor necrosis factor-alpha gene polymorphism and Sasang constitution in cerebral infarction.

During the last decade, a growing corpus of evidence has indicated an important role of cytokines in the development of brain damage following cerebral ischemia. Tumor necrosis factor-alpha (TNF-alpha), a potent immunomodulator and pro-inflammatory cytokine, has been implicated in many pathological processes. In this study, we examined whether promoter region polymorphism in the TNF-alpha gene at position -308 affects the odds of cerebral infarction (CI) and whether genetic risk is enhanced by Sasang constitutional classification. Two hundred and twelve CI patients and 610 healthy controls were genotyped and determined according to Sasang constitutional classification. A significant decrease was found for the TNF-alpha A allele in CI patients compared with controls (p = 0.033, odds ratio, OR: 0.622). However, there was no significant association between TNF-alpha polymorphism and Sasang constitution in CI patients. Our finding suggests that TNF-alpha promoter region polymorphism is responsible for susceptibility to CI in Koreans.

The relationship between the visual prognoses of branch retinal artery obstruction and foveal thickness on OCT.

PURPOSE: To determine the correlation between the prognosis of branch retinal artery obstruction (BRAO) and the foveal thickness or outer nuclear layer (ONL) thickness on optical coherence tomography (OCT). METHODS: Twenty-one eyes (21 patients) in patients with resolved, non-complicated BRAO and a normal control of 10 eyes (10 volunteers) were used in this study. The average macular thickness, foveal thickness and ONL thickness at central fovea were measured in both the patients and the control group using spectral domain OCT. The thickness between the patient group and the control group were compared and correlation between the best corrected visual acuity (BCVA) and each thickness was determined. RESULTS: The average age of the patients was 52 ± 5.8 years. The average macular thickness, foveal thickness and ONL thickness at the central fovea of the patients were significantly (p < 0.001, p = 0.023, p = 0.021, respectively) thinner than that of the control group. Both the foveal thickness (r(s) = 0.56, p = 0.008) and ONL thickness (r(s) = 0.86, p < 0.001) were significantly correlated with BCVA. There was no significant correlation between the average macular thickness and BCVA. CONCLUSIONS: The foveal thickness and ONL thickness at the fovea was positively correlated with the BCVA in patients with resolved BRAO.

Clinical manifestation of Brugia malayi infection in Korea.

The clinical manifestations in filarial infection were examined during 1965-1966 from the known endemic areas: Yongju, a mountainous inland area and Cheju-Do, an island. 1. All the microfilaria which were found during the survey were Brugia malayi. 2. The principal symptom was cuticular hypertrophy (elephantiasis). It was found in 4 cases from Yongju among 707 villagers, 84 cases from Cheju-Do among 2,376 villagers. 3. Four microfilaremia cases (4.5%) were found among a total of 88 cases of elephantiasis. 4. In Cheju-Do, the higher incidence of elephantiasis was observed among people over 20 years old and the females showed much higher incidence than males (30 males and 54 females). 5. The cuticular hypertrophic changes (elephantiasis) appeared more often in the lower extremities(77%) than in the upper part of the body, and in the right side than in the left.

Treatment of hookworm infection with 2, 6-Diiodo-4-Nitrophenol.

Single dose(1.0 cc) of 20 % 2, 6-diiodo-4-nitrophenol solution was injected to 82 hookworm infected cases and 79% of them became egg-negative within 2-3 weeks after the injection. Mild to severe local pain were experienced for several minutes in all cases. Two cases complained of paralysis of the arms of the same side. The tablet of the same formula was given orally to 21 cases for 1-4 days. The 2-4 day course with 360 mg/day were enough to eliminate the parasite, and showed no systemic side effects.

[The egg detection rates of Enterobius vermicularis among school children in the various regions]

A total of 860 cellotape anal swab specimens from 326 school children of urban area, 243 of rura1 farm village and 291 of rural fishing village was submitted for Enterobius vermicularis egg detection from September through November 1985. Each specimen was collected in the morning. Among the total 860 children's submitting specimens, 316 (36.7 per cent) were positive for E. vermicularis eggs. Of the 326 children in the urban area, E. vermicularis eggs were detected in the 45 (13.8 per cent). This detection rate was lower significantly as compared with 143 (55.6 per cent) of 243 children in the farm village or 136 (46.7 per cent) of 291 children in the fishing village. The egg detection rate in the male children was lower remarkably than that in the female children.

Enhanced expression of the gene for beta-glycosidase of Thermus caldophilus GK24 and synthesis of galacto-oligosaccharides by the enzyme.

The gene (bglT) encoding Tca beta-glycosidase (Thermus caldophilus GK24 beta-glycosidase) was overexpressed under the control of the trp promoter on a high-copy-number plasmid, pTRPES, in Escherichia coli W3110. The purified Tca beta-glycosidase enzyme was used in a galactosyl-transfer reaction to synthesize galacto-oligosaccharides from lactose. The optimum temperature and pH for the enzyme to synthesize galacto-oligosaccharides from 30% (w/v) lactose were 80 degrees C and 6.0, respectively. The major product of the reaction was a trisaccharide. The thermostable Tca beta-glycosidase produced galacto-oligosaccharides efficiently during the hydrolysis of lactose.