• Elastomers and Composites
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• v.40 no.1
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• pp.22-28
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• 2005

In this work, the effect of oxygen plasma treatment of nano-scaled silica on the mechanical interfacial properties and thermal stabilities of the silica/rubber composites was investigated. The surface properties of the silica were studied in X-ray photoelectron spectroscopy (XPS) and contact angles. And, their mechanical interfacial properties and thermal stabilities of the composites were characterized by tearing energy ($G_{IIIC}$) and thermogravimetric analysis (TGA), respectively. As a result, it was found that the introduction rate of oxygen-containing polar functional groups onto the silica surfaces was increased by increasing the plasma treatment time, resulting in improving the tearing energy. Also, the thermal stabilities of the composites were increased by increasing the treatment time. These results could be explained that the polar rubber, such as acrylonitrile butadiene rubber (NBR), showed relatively a high degree of interaction with oxygen-containing functional groups of the silica surfaces in a compounding system.

• Journal of Chest Surgery
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• v.25 no.12
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• pp.1391-1398
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• 1992

The hypothesis tested is that shifts in pH, induced when a cardioplegic solution is oxygenated, can be detrimental. The object of this study is to evaluate the effect of the pH of the oxygenating cardioplegic solution on postischemic recovery in the isolated rat heart. Either 100% oxygen or 95% oxygen: 5% carbon dioxide was added to the cardioplegic solution[St. Thomas` Hospital No. 2] and determined postischemic recovery of isolated rat hearts after 2 hours and 3 hours of 20oC cardioplegic protected ischemia. Heart were arrested and reinfused every 30 minutes throughout the ischemic period with cardioplegic solution. When 100% oxygen was added, the pH of the cardioplegic solution increased from 7.8[no oxygen] to 8.5[100% oxygen] without any change in postischemic functional recovery. But when 95% oxygen ; 5% carbon dioxide was added, the pH of the cardioplegic solution reversely decreased to 6.84 in the 2-hour ischemic group and 6.73 in the 3-hour ischemic group, associated with improved postischemic functional recovery. After 2-hour ischemia, systolic pressure improved from 88.2$\pm$3.7%[no oxygen] and 88.7$\pm$3.8%[100% oxygen] to 96.6$\pm$1.8%[95% oxygen : 5% carbon dioxide], p<0.05, aortic flow from 43.3$\pm$3.1% and 38.4$\pm$10.6% to 74.5$\pm$5.0%, p<0.001, cardiac output from 55.5$\pm$4.6% and 47.4%$\pm$10.6% to 73.1$\pm$4.6%, p<0.05, stroke volume from 62.7$\pm$4.6% and 52.0$\pm$10.1% to 77.2$\pm$4.6%, p<0.05, and dP/dT from 59.3$\pm$7.2% and 56.7$\pm$7.6% to 78.9$\pm$4.6%, p<0.05. The infused amount of the cardioplegic solution during 2-hour ischemic period was similar in three groups. After 3-hour ischemia, cardiac output improved from 17.0$\pm$3.8%[no oxygen] to 45.9$\pm$7.5%[95% oxygen: 5% carbon dioxide], p<0.05, and stroke volume from 21.0$\pm$3.9%[no oxygen] to 50.1$\pm$6.6%[95% oxygen: 5% carbon dioxide], p<0.01. In conclusion, the St. Thomas` Hospital No. 2 cardioplegic solution should be oxygenated but with 95% oxygen: 5% carbon dioxide and not 100% oxygen because of the additive effect of a relatively "Acidotic" pH.t; pH.

• Carbon letters
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• v.6 no.2
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• pp.106-110
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• 2005

In this work, the effects of atmospheric oxygen plasma treatment of carbon fibers on mechanical interfacial properties of carbon fibers-reinforced epoxy matrix composites was studied. The surface properties of the carbon fibers were determined by acid/base values, Fourier-transform infrared spectrometer (FT-IR), and X-ray photoelectron spectroscopy (XPS) analyses. Also, the crack resistance properties of the composites were investigated in critical stress intensity factor ($K_{IC}$), and critical strain energy release rate mode II ($G_{IIC}$) measurements. As experimental results, FT-IR of the carbon fibers showed that the carboxyl/ester groups (C=O) at 1632 $cm^{-1}$ and hydroxyl group (O-H) at 3450 $cm^{-1}$ were observed for the plasma treated carbon fibers, and the treated carbon fibers had the higher O-H peak intensity than that of the untreated ones. The XPS results also indicated that the $O_{1S}/C_{1S}$ ratio of the carbon fiber surfaces treated by the oxygen plasma led to development of oxygen-containing functional groups. The mechanical interfacial properties of the composites, including $K_{IC}$ (critical stress intensity factor) and $G_{IIC}$ (critical strain energy release rate mode II), were also improved for the oxygen plasma-treated carbon fibersreinforced composites. These results could be explained that the oxygen plasma treatment played an important role to increase interfacial adhesions between carbon fibers and epoxy matrix resins in our composite system.

• Polymer(Korea)
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• v.29 no.1
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• pp.32-35
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• 2005

In this paper, the carbon nanotubes (CNTs) were ozonized and the positive temperature coefficient (PTC) behaviors of CNTs-filled high-density polyethylene (HDPE) conductive composites were studied. The results of element analysis (EA) and FT-IR indicate that the oxygen-containing functional groups on the CNTs surfaces, such as O-H, C-O, and C＝O groups, were increased with the ozonization. Electrical resistivities of the CNTs/HDPE composites were measured by using a digital multimeter. The resistivity of the composites was increased abruptly near the crystalline melting temperature of the HDPE used as matrix, which could be attributed to the destruction of conductive network by the thermal expansion of HDPE. And, the PTC intensity of the CNTs/HDPE composites was increased with the increase of the ozone treatment time. It was probably due to the growing of maximum volume resistivity of the composites induced by the increased oxygen-containing functional groups in the CNTs surfaces.

• Carbon letters
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• v.16 no.2
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• pp.93-100
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• 2015

Surface modified carbon felts were utilized as an electrode for the removal of inorganic ions from seawater. The surfaces of the carbon felts were chemically modified by alkaline and acidic solutions, respectively. The potassium hydroxide (KOH) modified carbon felt exhibited high Brunauer-Emmett-Teller (BET) surface areas and large pore volume, and oxygen-containing functional groups were increased during KOH chemical modification. However, the BET surface area significantly decreased by nitric acid ($HNO_3$) chemical modification due to severe chemical dissolution of the pore structure. The capability of electrosorption by an electrical double-layer and the efficiency of capacitive deionization (CDI) thus showed the greatest enhancement by chemical KOH modification due to the appropriate increase of carboxyl and hydroxyl functional groups and the enlargement of the specific surface area.

• Journal of the Korean Chemical Society
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• v.57 no.1
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• pp.104-108
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• 2013

The adsorption characteristics of Cd(II) and Pb(II) in aqueous solution using granular activated carbon (GAC), activated carbon fiber (ACF), modified ACF (NaACF), and a mixture of GAC and NaACF (GAC/NaACF) have been studied. The surface properties, such as morphology, surface functional groups, and composition of various adsorbents were determined using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) measurements. The specific surface area, total pore volume, and pore size distribution were investigated using nitrogen adsorption, Brunauer-Emmett-Teller (BET), and Barrett-Joyner-Halenda (BJH) methods. In this study, NaACF showed a high adsorption capacity and rate for heavy metal ions due to the improvement of its ion-exchange capabilities by additional oxygen functional groups. Moreover, the GAC and NaACF mixture was used as an adsorbent to determine the adsorbent-adsorbate interaction in the presence of two competitive adsorbents.

• Korean Journal of Materials Research
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• v.12 no.9
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• pp.740-746
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• 2002

In this study, the polycarbonate surface was treated by $O_2$/ Ar gases plasma for the enhancement of adhesion with Cu electrode. From the point of view of hydrophilicity and the functionality, the micro-roughness, new functional groups and oxygen content of the polycarbonate surface were increased by the $O_2$/ Ar gases plasma treatment. The Cu films deposited on the as-received polycarbonate were easily detached while, after the$ O_2$/ Ar gases plasma treatment the adhesive Cu films on polycarbonate could be obtained. These results can be explained that the polycarbonate had a hydrophilic surface with uniform micro-roughness and new functional groups by $O_2$/ Ar gases plasma treatment. Therefore,$O_2$/ Ar gases plasma treatment is a promising method for improvement of adhesion between polycarbonate and Cu electrode.

• Journal of the Korean institute of surface engineering
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• v.49 no.3
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• pp.265-273
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• 2016

The effects of surface modification by nitric acid on the pre-treatment of electroless copper plating were investigated. Copper was electroless-plated on the nitric acid treated graphite activated by a two-step pre-treatment process (sensitization + activation). The chemical state and relative quantities of the various surface species were determined by X-ray photoelectron spectroscopy (XPS) after nitric acid modification or pre-treatment. The acid treatment increased the surface roughness of the graphite due to deep and fine pores and introduced the oxygen-containing functional groups (-COOH and O-C=O) on the surface of graphite. In the pre-treatment step, the high roughness and many functional groups on the nitric acid treated graphite promoted the adsorption of Sn and Pd ions, leading to the uniform adsorption of catalyst ($Pd^0$) for Cu deposition. In the early stage of electroless plating, a lot of tiny copper particles were formed on the whole surface of acid treated graphite and then homogeneous copper film with low variation in thickness was formed after 30 min.

• Applied Chemistry for Engineering
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• v.28 no.6
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• pp.638-644
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• 2017

Pitch based activated carbon fibers for electric double layer capacitor (EDLC) electrodes were treated by oxyfluorination via varying the ratio of fluorine and oxygen gases to improve high power property. As the partial pressure of fluorine increased, the oxyfluorinated activated carbon fibers showed an increase of linear fluorine functional groups. While the oxygen functional groups increased, no changes was observed with respect to the partial gas pressure. The specific surface area and pore volume decreased due to the etching reaction on the activated carbon fiber surface through oxyfluorination, but the mesopore volume increased about 4.5 times. In the case of activated carbon fibers treated with 50% of the fluorine gas partial pressure, the specific capacitance increased to about 29% and 61% at scan rates of 5 and 50 mV/s, respectively. The improvement of the specific capacitance was believed to be due to the introduction of oxygen and fluorine functional groups on the activated carbon fiber surface and the increase of mesopores through oxyfluorination.

• Journal of Photoscience
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• v.7 no.4
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• pp.143-148
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• 2000

Studies have been conducted to explore single electron transfer(SET) promoted photocyclization of ($\omega$-phthalimidoalkoxy)acetic acids(alkoxy=ethoxy, n-propoxy and n-butyloxy). Photocyclizations occur in methanol or acetone in high yields to produce cyclized products in which phthalimide carbonyl carbon is bonded to the carbon of side chain in place of the carboxylic group. These photocyclizations are thought to proceed through pathways involving intramolecular SET from oxygen in the $\alpha$-carboxymethoxy groups to the singlet excited state phthalimide moieties followed by decarboxylation of the intermediate $\alpha$-carboxymethoxy cation fadicals and cyclizations by radical coupling. The photocyclizations occur ca. three times faster in both methanol or acetone with one equivalent of sodium hydroxide added to the reactions and occur slower in acetone than in methanol. The efficient and regiselective cyclization reactions observed for photolyses in methanol represent synthetically useful processes for construction of heterocyclic compounds.