• The Journal of Advanced Prosthodontics
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• 제11권1호
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• pp.1-6
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• 2019

PURPOSE. The purpose of this in vitro study was to evaluate the effect of surface grinding and polishing procedures using high speed zirconia diamond burs with different grit sizes on the phase transformation and flexural strength of zirconia. MATERIALS AND METHODS. Forty disc shape specimens ($15{\times}1.25mm$) with a cylindrical projection in the center of each disc ($1{\times}3mm$) were fabricated with 3Y-TZP (Prettau, Zirkonzahn, Italy). The specimens were divided into 4 groups (n=10) according to the grinding and polishing procedures: Control group - grinding (coarse-grit diamond bur), Group 1 - grinding (coarse-grit diamond bur) + polishing, Group 2 - grinding (fine-grit diamond bur) + polishing, and Group 3 - grinding (fine grit diamond bur). Each specimen was analyzed by 3D-OM, XRD analysis, and biaxial flexural strength test. RESULTS. Based on the surface morphology by 3D-OM images, polished specimens showed smoother surface and lower roughness value (Ra). In the result of XRD analysis, partial phase transformation from tetragonal to monoclinic zirconia occurred in all groups. Control group, ground with a coarse grit diamond bur, showed more $t{\rightarrow}m$ phase transformation and lower flexural strength than Groups 1 and 2 significantly. CONCLUSION. The flexural strength in all specimens after grinding and polishing showed over 500 MPa, and those were clinically acceptable. However, grinding with a coarse grit diamond bur without polishing induced the phase transformation and low strength. Therefore, surface polishing is required for the occlusal adjustment using a high speed zirconia diamond bur to reduce the phase transformation and to prevent the decrease of flexural strength of zirconia.

• Journal of Microbiology and Biotechnology
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• 제34권5호
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• pp.1051-1058
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• 2024

This study investigated the impact of inulin (INL) on viability of L. plantarum D-2 (LPD2) by encapsulation through spray drying (SD) and its commercialization potential to alternative of conventional wall material maltodextrin (MD). LPD2, derived from sea tangle (Saccharina japonica) kimchi, is probiotics exhibiting significant attributes like cholesterol reduction, antioxidant properties, and resilience to acidic and bile environments. To enhance storage viability and stability of LPD2, encapsulation was applied by SD technology. The optimum encapsulation condition with MD was 10% MD concentration (MD10) and inlet temperature (96℃). The optimum concentration ratio of MD and INL was 7:3 (INL3) for alternative of MD with similar encapsulation yield and viability of LPD2. Viability of LPD2 with INL3 exhibited almost 8% higher than that with MD10 after 50 days storage at 25℃. Physicochemical characteristics of the encapsulated LPD2 (ELPD2) with MD10 and INL3 had no significant different between flowability and morphology. But, ELPD2 with INL3 had lower water solubility and higher water absorption resulting in extension of viability of LPD2 compared to that with MD10. The comprehensive study results showed that there was no significant difference in the encapsulation yield and physicochemical properties between ELPD2 with MD10 and INL3, except of water solubility index (WSI) and water absorption index (WAI). INL have the potential to substitute of MD as a commercial wall material with prebiotic functionality to enhance the viability of LPD2 by encapsulation.

• The Journal of Advanced Prosthodontics
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• 제16권2호
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• pp.126-138
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• 2024

PURPOSE. The aim of this study was to evaluate the influence of different 3D dental resins, using a manufacturer recommended printer and a third-party printer, on cellular responses of human gingival cells. MATERIALS AND METHODS. Three NextDent resins (Denture 3D+, C&B MFH and Crowntec) were used to produce specimens on printers NextDent 5100 (groups ND, NC and NT, respectively) and Phrozen Sonic Mini 4K (groups PD, PC and PT, respectively). Human gingival fibroblasts were cultured and biocompatibility was evaluated on days 1, 3 and 7. IL-6 and IL-8 concentrations were evaluated at 3 days using ELISA. Surface roughness was evaluated by a contact profilometer. SEM and fluorescence micrographs were analyzed at days 1 and 7. Statistical analyses were performed using SPSS and mean differences were tested using ANOVA and post-hoc Tukey tests (P < .05). RESULTS. There was an increase in cellular viability after 7 days in groups PC and PT, when compared to group PD. ND group resulted in higher concentration of IL-6 when compared to PT group. SEM and fluorescence micrographs showed less adhesion and thinner morphology of fibroblasts from group PD. No significant differences were found regarding surface roughness. CONCLUSION. The use of different printers or resins did not seem to influence surface roughness. NextDent 5100 and Phrozen Sonic Mini 4K produced resins with similar cellular responses in human gingival fibroblasts. However, Denture 3D+ resin resulted in significantly lower biocompatibility, when compared to C&B MFH and Crowntec resins. Further testing is required to support its long-term use, required for complete dentures.

• Transactions on Electrical and Electronic Materials
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• 제6권3호
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• pp.124-127
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• 2005

It has been a long time since organic solar cells were expected as a low-cost energy-conversion device. Although practical use of them has not been achieved, technological progress continues. Morphology of the materials, organic/inorganic interface, metal cathodes, molecular packing and structural properties of the donor and acceptor layers are essential for photovoltaic response. We have fabricated solar cell devices based on zinc-phthalocyanine(ZnPc) as donor(D) and fullerene$(C_60)$ as electron acceptor(A) with doped charge transport layers, and BCP and $Alq_3$ as an exciton blocking layer(EBL). We have measured the photovoltaic characteristics of the solar cell devices using the Xe lamp as a light source. We were use of $Alq_3$ layer leads to external power conversion efficiency was $2.65\%$ at illumination intensity $100\;mW/cm^2$. Also we confirmed the optimum thickness ratio of the DA hetero-junction is about 1:2.

• 한국재료학회지
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• 제18권3호
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• pp.163-168
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• 2008

The morphology of three-dimensional (3D) cross-linked electrodeposits of copper and tin was investigated as a function of the content of metal sulfate and acetic acid in a deposition bath. The composition of copper sulfate had little effect on the overall copper network structure, whereas that of tin sulfate produced significant differences in the tin network structure. The effect of the metal sulfate content on the copper and tin network is discussed in terms of whether or not hydrogen evolution occurs on electrodeposits. In addition, the hydrophobic additive, i.e., acetic acid, which suppresses the coalescence of evolved hydrogen bubbles and thereby makes the pore size controllable, proved to be detrimental to the formation of a well-defined network structure. This led to a non-uniform or discontinuous copper network. This implies that acetic acid critically retards the electrodeposition of copper.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2009년도 추계학술발표대회
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• pp.12.1-12.1
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• 2009

Nano-hydroxyapatite (N-HAp)has shown the pivotal role in producing bone-regenerative materials since it has similarity to natural bone minerals in terms of size, morphology, and the composition. Currently, the combination of biopolymers and N-HAp is recognizedas an attractive approach in generating hybrid scaffolds for bone tissueengineering. Surface engineering is an important issue since it determines whether cells can effectively adhere and proliferate on porous scaffolds. We aim to develop a synthetic approach to porous 3D scaffolds by immobilizing N-HAp on pore surfaces. The discrete nano-level anchoring of N-HAp on the scaffold pore surface is achieved using surface-repellent stable colloidal N-HAp with surface phosphate functionality. This rational surface engineering enables surface-anchored N-HAp to express its overall intrinsic bioactivity,since N-HAp is not phase-mixed with the polymers. The porous polymer scaffolds with surface-immobilized N-HAp provide more favorable environments thanconventional bulk phase-mixed polymer/N-HAp scaffolds in terms of cellular interaction and growth. In vitro biological evaluation using alkalinephosphatase activity assay supports that immobilized N-HAp on pore surfaces of polymer scaffolds contributed to the more enhanced in vitro osteogenicpotential. Besides, the scaffolds with surface-exposed N-HAp provide favorable environments for enhanced in vivo bone tissue growth, estimated by characteristic biomarkers of bone formation such as collagen. The results suggest that newly developed hybrid scaffolds with surface-immobilized N-HApmay serve as a useful 3D substrate with pore surfaces featuring excellent bonetissue-regenerative properties. Acknowledgement. This research was supported by a grant (code #: 2009K000430) from 'Center for Nanostructured Materials Technology' under '21st Century Frontier R&D Programs' of the Ministry of Education, Science and Technology, Korea.

• 대한한의학방제학회지
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• 제27권1호
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• pp.53-63
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• 2019

Objectives : In this study, we investigated the combination effects of Cinnamomi cortex Ethanol Extract (CcEE) and hyperthermia in the human AGS gastric cancer cell line. Methods : AGS cells were treated with the indicated concentrations of CcEE (0, 50 or $60{\mu}g/mL$) for 1h prior to hyperthermia. And then incubated for a further 30 min at the indicated temperatures (37, 42 or $43^{\circ}C$) in a humidified incubator containing 5% $CO_2$ or a thermostatically controlled water bath for hyperthermia. The cell viability was measured by MTT assay, Morphology assay and Trypan blue assay. To investigate the possible molecular signaling pathways, the activation of mitogen-activated protein kinase (MAPK) proteins (ERK, p38 and JNK) and expression of various anti-apoptotic proteins such as Caspase-3, Caspase-9, p53, Cyclin D1 and MMP-2 were assessed by Western blot analysis. In addition, Annexin V and 7-amino-actinomycin D (7-AAD) staining was performed to examine the apoptotic mechanism. Results : Combination of CcEE with hyperthermia effectively suppressed the cell viability and changed cellmorphology compared with CcEE or hyperthermia treatment alone. Combined treatment also abated the expression of Caspase-3, Caspase-9, Cyclin D1 and MMP-2. Whereas, the expression level of p53 was up-regulated by co-treatment. Moreover, combination treatment enhanced phosphorylation of ERK, p38 and JNK. In addition, this combination increased anti-cancer effect by inducing cell death through the apoptosis. Conclusions : Taken together, all these findings suggest that the combination treatment with CcEE and hyperthermia may have therapeutic potential as a promising approach to patients with stomach cancer.

• 대한치과교정학회지
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• 제53권5호
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• pp.317-327
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• 2023

Objective: This study aimed to evaluate the association between low tongue position (LTP) and the volume and dimensions of the nasopharyngeal, retropalatal, retroglossal, and hypopharyngeal segments of the upper airway. Methods: A total of 194 subjects, including 91 males and 103 females were divided into a resting tongue position (RTP) group and a LTP group according to their tongue position. Subjects in the LTP group were divided into four subgroups (Q1, Q2, Q3, and Q4) according to the intraoral space volume. The 3D slicer software was used to measure the volume and minimum and average cross-sectional areas of each group. Airway differences between the RTP and LTP groups were analyzed to explore the association between tongue position and the upper airway. Results: No significant differences were found in the airway dimensions between the RTP and LTP groups. For both retropalatal and retroglossal segments, the volume and average cross-sectional area were significantly greater in the patients with extremely low tongue position. Regression analysis showed that the retroglossal airway dimensions were positively correlated with the intraoral space volume and negatively correlated with A point-nasion-B point and palatal plane to mandibular plane. Males generally had larger retroglossal and hypopharyngeal airways than females. Conclusions: Tongue position did not significantly influence upper airway volume or dimensions, except in the extremely LTP subgroup.

• 한국축산식품학회지
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• 제40권4호
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• pp.497-511
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• 2020

This study aimed at comparing the storage stability, fatty acids profile, volatile flavor compounds and eating quality of Hanwoo beef longissimus thoracis (LT) muscles between two marbling morphological groups (fineness and coarseness). The 1⁺ grade Hanwoo LT muscles were measured for marbling fleck morphology at the 13^th thoracic vertebrae location by using computerized image analysis. Results reveal that both marbling groups had similar proximate composition (protein, fat, moisture and collagen), color and technological quality traits (p>0.05). However, the coarse marbling group presented greater C18:2n6 and polyunsaturated fatty acids contents compared to the fine marbling group (p<0.05). Furthermore, the fine marbling group presented lower volatile basic nitrogen (VBN) and 2-thiobarbituric acid reactive substance (TBARS) contents compared to the coarse marbling group after 14 d storage (p<0.05). Also, higher amounts of C18:2n6 oxidation-derived volatile compounds such as hexanal and 3-ethyl-2-methyl-1,3-hexadiene, were found in the coarse marbling group. In term of sensory aspects, the finely-marbled group received higher scores of flavor and taste compared to the coarse marbling group (p<0.05). Overall, the marbling flecks morphology partially showed its effects on the storage stability, fatty acids profile and eating quality of the 1⁺ grade Hanwoo beef LT muscle.

• Journal of Electrochemical Science and Technology
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• 제9권3호
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• pp.202-211
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• 2018

In this work, Fe-Pd alloy films have been electrodeposited on different substrates using an electrolyte containing $[Pd(NH_3)_4]^{2+}$ (0.02 M) and $[Fe-Citrate]^{2+}$ (0.2 M). The influences of substrate and overpotential on chemical composition, nucleation and growth kinetics as well as the electrodeposited films morphology have been investigated using energy dispersive X-ray spectroscopy (EDS), current-time transients, scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray diffraction (XRD) patterns. In all substrates - brass, copper and sputtered fluorine doped tin oxide on glass (FTO/glass) - Fe content of the electrodeposited alloys increases by increasing the overpotential. Also the cathodic current efficiency is low due to high rate of $H_2$ co-reduction. Regarding the chronoamperometry current-time transients, it has been demonstrated that the nucleation mechanism is instantaneous with a typical three dimensional (3D) diffusion-controlled growth in the case of brass and copper substrates; while for FTO, the growth mode changes to 3D progressive. At a constant overpotential, the calculated number of active nucleation sites for metallic substrates is much higher than that of FTO/glass; however by increasing the overpotential, the number of active nucleation sites increases. The SEM micrographs as well as the XRD patterns reveal the formation of Fe-Pd alloy thin films with nanostructure arrangement and ultra-fine grains.