• Journal of the Korean Chemical Society
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• v.42 no.2
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• pp.214-219
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• 1998

Dynorphin B analogues, $[Arg^{11}, D-Ala^{12}]$dynorphin B, $[D-Ala^2, Ala^6, Arg^{11}, D-Ala^{12}]$dynorphin B, and dynorphin B (1-11) were synthesized by solid-phase method. A chloromethylated polystyrene resin cross-linked with 2% divinylbenzene was substituted with Thr in ethanol to contain 1.20 mmol Thr/g of resin. All amino groups of amino acids were protected with t-Boc group and 2,6-dichlorobenzyl and nitro groups were used to protect the side chains of Tyr and Arg, respectively. Stepwise synthetic method was applied for synthesis of the products. Dicyclohexylcarbodiimide (DCC) and 1-hydroxybenzotriazole (HOBT) were used as the coupling reagents. The crude peptides were purified by gel filteration on Sephadex LH-20 column $(2 \times 50 cm)$ using MeOH/MeCN (3/1) and then characterized with HPLC, amino acid analyzer.

• Applied Chemistry for Engineering
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• v.7 no.2
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• pp.341-349
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• 1996

To improve the dyeability of polyurethane (PU) resin, low molecular weight diols containing dye site in the molecular structure was added as a chain-extender. PU resin were synthesized with the variations in the chain extender, polyol type, and hard segment/soft segment (HS/SS) ratio. When HS/SS ratio is 1.4 and dimethylolpropionic acid(DMPA) or N-butyldiethanolamine (BDEA) was used as a chain extender, because of heterogeneity of reaction mechanical properties were diminished. But when N-methyldiethanolamine (MDEA) was used as a DCE, and HS/SS ratio lowed to 1.3, mechanical properties and dyeability improved. In particular, when linear type 1,4-BD was formulated with MDEA, hydrolysis resistance and mechanical properties of PTMG type PU was improved. And initial elasticity, tensile strength and elongation could be controlled by the variation of HS/SS ratio, DCE mixing ratio of 1,6-HD or NPG.

• Elastomers and Composites
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• v.43 no.4
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• pp.241-252
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• 2008

ZnAl-LDH(layered double hydroxide) modified with oleic acid(SO-ZnAl LDH) was synthesized and added to the flame retardant ABS compounds containing brominated epoxy resin(BER) and antimony trioxide(${Sb_2}{O_3}$). Flame retardant ABS compounds were manufactured by using a twin-screw co-rotating extruder and subsequently injection molded into several specimen for flame retardancy and mechanical properties. The XRD patterns of ABS nanocomposites showed no peaks. The thermal stability of ABS nanocomposites was enhanced by the addition of SO-ZnAl LDH as shown in TGA results. However, these nanocomposites showed no rating in the UL 94 vertical test at 1.6 mm thickness. Only ABS nanocomposites with additional BER more than 1.5 wt% showed UL 94 V0 rating. Notched Izod impact strength, tensile modulus, and elongation at break of flame retardant ABS nanocomposites increased with the proportion of So-ZnAl LDH whereas their melt index decreased.

• The korean journal of orthodontics
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• v.48 no.4
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• pp.245-252
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• 2018

Objective: We aimed to perform in-vitro evaluation to compare 1) shear bond strength (SBS), adhesive remnant index (ARI), and color change between self-etched and acid-etched primers; 2) the SBS, ARI and color change between direct and indirect bonding; and 3) the enamel roughness (ER) between 12-blade bur and aluminum oxide polisher debonding methods. Methods: Seventy bovine incisors were distributed in seven groups: control (no bonding), direct (DTBX), and 5 indirect bonding (ITBX, IZ350, ISONDHI, ISEP, and ITBXp). Transbond XT Primer was used in the DTBX, ITBX, and ITBXp groups, flow resin Z350 in the IZ350 group, Sondhi in the ISONDHI group, and SEP primer in the ISEP group. SBS, ARI, and ER were evaluated. The adhesive remnant was removed using a low-speed tungsten bur in all groups except the ITBXp, in which an aluminum oxide polisher was used. After coffee staining, color evaluations were performed using a spectrophotometer immediately after staining and prior to bonding. Results: ISONDHI and ISEP showed significantly lower SBS (p < 0.01). DTBX had a greater number of teeth with all the adhesive on the enamel (70%), compared with the indirect bonding groups (0-30%). The ER in the ITBX and ITBXp groups was found to be greater because of both clean-up techniques used. Conclusions: Direct and indirect bonding have similar results and all the primers used show satisfactory adhesion strength. Use of burs and polishers increases the ER, but polishers ensure greater integrity of the initial roughness. Resin tags do not change the color of the teeth.

• The Journal of Advanced Prosthodontics
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• v.7 no.3
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• pp.224-232
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• 2015

PURPOSE. The purpose of this study was to find out the effect of immediate dentin sealing (IDS) on bond strength of ceramic restoration under various thermocycling periods with DBA (dentin bonding agent system). MATERIALS AND METHODS. Fifty freshly extracted human mandibular third molars were divided into 5 groups (1 control and 4 experimental groups) of 10 teeth. We removed enamel layer of sound teeth and embedded them which will proceed to be IDS, using All Bond II. A thermocycling was applied to experimental groups for 1, 2, 7, 14 days respectively and was not applied to control group. IPS Empress II for ceramic was acid-etched with ceramic etchant (9.5% HF) and silane was applied. Each ceramic disc was bonded to specimens with Duo-link, dual curable resin cement by means of light curing for 100 seconds. After the cementation procedures, shear bond strength measurement and SEM analysis of the fractured surface were done. The data were analyzed with a one-way ANOVA and Tukey multiple comparison test (${\alpha}$=.05). RESULTS. There were no statistically significant differences between 4 experimental groups and control group, however the mean value started to decrease in group 7d, and group 14d showed the lowest mean bond strength in all groups. Also, group 7d and 14d showed distinct exposed dentin and collapsed hybrid layer was observed in SEM analysis. CONCLUSION. In the present study, it can be concluded that ceramic restorations like a laminate veneer restoration should be bonded using resin cement within one week after IDS procedure.

• The Journal of Advanced Prosthodontics
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• v.9 no.5
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• pp.350-357
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• 2017

PURPOSE. The object of the present study was to evaluate the shear bonding strength of composite to PEKK by applying several methods of surface treatment associated with various bonding materials. MATERIALS AND METHODS. One hundred and fifty PEKK specimens were assigned randomly to fifteen groups (n = 10) with the combination of three different surface treatments (95% sulfuric acid etching, airborne abrasion with $50{\mu}m$ alumina, and airborne abrasion with $110{\mu}m$ silica-coating alumina) and five different bonding materials (Luxatemp Glaze & Bond, Visio.link, All-Bond Universal, Single Bond Universal, and Monobond Plus with Heliobond). After surface treatment, surface roughness and contact angles were examined. Topography modifications after surface treatment were assessed with scanning electron microscopy. Resin composite was mounted on each specimen and then subjected to shear bond strength (SBS) test. SBS data were analyzed statistically using two-way ANOVA, and post-hoc Tukey's test (P<.05). RESULTS. Regardless of bonding materials, mechanical surface treatment groups yielded significantly higher shear bonding strength values than chemical surface treatment groups. Unlike other adhesives, MDP and silane containing self-etching universal adhesive (Single Bond Universal) showed an effective shear bonding strength regardless of surface treatment method. CONCLUSION. Mechanical surface treatment behaves better in terms of PEKK bonding. In addition, self-etching universal adhesive (Single Bond Universal) can be an alternative bonding material to PEKK irrespective of surface treatment method.

• Journal of Radiation Protection and Research
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• v.20 no.1
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• pp.1-7
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• 1995

Strontium selective chromatographic material $(Sr-Spec^{TM})$ was investigated for separation of radiostrontium from environmental soil and water sample. This chromatographic material has great capacity of binding of strontium ion in nitric acid media, and has selectivity to permit the separation of stontium from bulk amount of calcium. But the extraction of strontium was reduced by the other interfering ions such as K and Ba. So, in order to apply this material to the soil sample, prior removal treatment of K and Ba was needed. But the Sr-Spec material could provides simple and effective methods for the separation and removal of radiostrontium from liquid sample.

• Biomedical Science Letters
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• v.2 no.2
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• pp.257-265
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• 1996

Simple stain and electron microscopic in situ hybridization is studied and applied for the identification of rabbit haemorrhagic disease viral RNA in a unicrylated preparation of the liver after innoculation of rabbit haemorrhagic disease virus. Hybridization for detection of viral RNA in unicryl embedded tissues using complementary 84 bases oligonucleotide probe labelled by biotin CE-phosphoramidite compared with 4717∼4800 sequences of rabbit haemorrhagic disease virus, modified hybridization protocol and antibiotin antibody-l0nm gold as signal marker. The best results were obtained in 0.02% glutaraldehyde, Unicryl resin cell block, biotinylated oligonucleotide probes, antibiotin-l0nm gold. In this report, RHD viral RNA was distributed widely within the mitochondria and nucleus of liver cell by electron microscopic in situ hybridization. In situ hybridization has become a standard method for localizing DNA or RNA sequences in tissue or celt preparation. In situ hybridization is detected the virus genome in the cells and tissue as specifically compared with others nucleic acid hybridization method.

• The Journal of Advanced Prosthodontics
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• v.12 no.1
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• pp.22-32
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• 2020

PURPOSE. The aim of this study was to evaluate the microshear bond strength (µSBS) of four computer-aided design/computer-aided manufacturing (CAD/CAM) blocks repaired with composite resin using three different surface treatment protocols. MATERIALS AND METHODS. Four different CAD/CAM blocks were used in this study: (1) flexible hybrid ceramic (FHC), (2) resin nanoceramic (RNC), (c) polymer infiltrated ceramic network (PICN) and (4) feldspar ceramic (FC). All groups were further divided into four subgroups according to surface treatment: control, hydrofluoric acid etching (HF), air-borne particle abrasion with aluminum oxide (AlO), and tribochemical silica coating (TSC). After surface treatments, silane was applied to half of the specimens. Then, a silane-containing universal adhesive was applied, and specimens were repaired with a composite, Next, µSBS test was performed. Additional specimens were examined with a contact profilometer and scanning electron microscopy. The data were analyzed with ANOVA and Tukey tests. RESULTS. The findings revealed that silane application yielded higher µSBS values (P<.05). All surface treatments were showed a significant increase in µSBS values compared to the control (P<.05). For FHC and RNC, the most influential treatments were AlO and TSC (P<.05). CONCLUSION. Surface treatment is mandatory when the silane is not preferred, but the best bond strength values were obtained with the combination of surface treatment and silane application. HF provides improved bond strength when the ceramic content of material increases, whereas AlO and TSC gives improved bond strength when the composite content of material increases.

• Korean Journal of Materials Research
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• v.8 no.11
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• pp.1061-1066
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• 1998

The synthesises of anion exchange resin from 4vinylpyridine-divinyIbenzene(4-VP-DVB) were intented to separate boron ion. The heterogeneous anion exchange membranes were prepared with polyethylene(PE) matrix bythe hot press method. The prepared exchange membranes were characterized by FT-IR, conductormeter and pH meter to confirm structural, mechanical and electrochemical properties. Their capacities were measured by changing floe rate and voltage. The best seperation capacity was appeared in the heterogeneous membrane which contains 50 wt % 4-VP-DVB resin within PE matrix. The heterogeneous membranes treated with acid were better than that treated with water. Results from this experiment were indicated that the optimal flow rate, voltage. and time in the seperation of boron ion were lOml/min, 18volts, and 4 hours respectively.