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ABSTRACT: We conducted experiments to determine the most effective calcium chelating agents for use in enhancing adhesion of human bone marrow mesenchymal stem cells (BM-MSCs) on nano-hydroxyapatite (nHAp)-coated titanium substrates by covalently immobilizing bone morphogenetic protein-2 (BMP-2). The quantity of amine groups on the chitosan chelated surface was 7 µg/surface area, and it was 1.4 µg/surface area on the alendronate chelated surface. The quantity of BMP-2 on the BMP-2 immobilized surface chelated with chitosan (4 ng/surface area) was higher than that on BMP-2 immobilized surface chelated with alendronate (2.2 ng/surface area). Contact angles of the nHAp-coated titanium, alendronate chelated, chitosan chelated, and BMP-2 immobilized surfaces chelated with alendronate were 68.8 ± 3.6°, 78.2 ± 1.9°, 74.8 ± 5.2°, and 76.0 ± 2.5°, respectively. The contact angle of the BMP-2 immobilized surface chelated with chitosan was significantly lower (56.2 ± 2.0°) than that of any of the other groups. BM-MSCs on the chitosan surface and BMP-2 immobilized on the surface chelated with chitosan appeared to be healthy and showed a spindle-like fibroblastic morphology. In addition, BM-MSCs on these surfaces appeared to have the ability to differentiate into bone-forming cells. We suggest that chitosan can be used as an effective calcium chelating agent for implants.
The International journal of artificial organs 05/2013; · 1.86 Impact Factor
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ABSTRACT: We demonstrated a highly efficient conducting indium tin oxide (ITO) core-TiO2 nanocrystals shell nanowire array for a photoelectrode in dye-sensitized solar cells with regard to light harvest and charge collection. The TiO2 shell layer, consisting of anatase nanocrystals of ∼2 nm, were successfully formed on a single crystalline ITO nanowire prepared via a vapor transport method using repetitive TiCl4 aqueous solution treatments at 50 °C. We found that the nanocrystal size and number of Cl(-) ions remaining on the formed shell layer critically influence the dye loading properties. Moreover, these factors can be controlled by means of a post-annealing process. We also found that the dye loading and the back electron transport from the conductive ITO nanowire to the electrolyte mainly determine the final cell performance. The proposed double-shell layer structure consisting of dense and porous layers showed significantly improved cell performance.
Nanoscale 03/2013; · 5.91 Impact Factor
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ABSTRACT: The synthesis of highly crystalline perovskite BaSnO nanoparticles for use as photoanode materials in dye-sensitized solar cells (DSSCs) is reported, and the photovoltaic properties of DSSCs based on BaSnO nanoparticles (BaSnO cells) are demonstrated. The resulting DSSCs exhibit remarkably rapid charge collection and a DSSC fabricated with a BaSnO film thickness of 43 µm leads to a high energy conversion efficiency of 5.2 %, which is one of the highest reported for ternary oxide-based DSSCs. More importantly, the BaSnO cells show superior charge collection in nanoparticle films compared to TiO cells and could offer a breakthrough in the efficiencies of DSSCs.
ChemSusChem 03/2013; 6(3):449-54. · 6.83 Impact Factor
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ABSTRACT: Accumulating evidence indicates that components of the systemic inflammatory response, such as C-reactive protein (CRP) and neutrophil-to-lymphocyte ratio (NLR), have been associated with prognosis of various cancers. We aimed to elucidate whether CRP and NLR could serve as potential surrogate markers for response and survival in patients with hepatocellular carcinoma (HCC).
The study population consisted of 318 consecutive patients with HCC. CRP and NLR were measured at baseline with follow-up measurements.
With the mean follow-up of 13.9 months, the median survival time was 13.8 months. Child-Pugh class, tumor size > 5 cm, tumor multiplicity, presence of portal vein thrombosis, α-fetoprotein > 200 ng/mL, CRP > 6.3 mg/L and NLR > 2.3 were identified as independent factors for worse survival of HCC (all p < 0.05). Patients with elevated CRP (> 6.3 mg/L) and elevated NLR (> 2.3) had a significantly shorter overall survival than those with low CRP and low NLR (all p < 0.001). The combined use of CRP and NLR provided incremental prognostic information. With significant inter-correlations, levels of CRP and NLR escalated with aggravating Child-Pugh class from A to C or progressing tumor stage from I to IV. CRP and NLR on baseline and serial measurements were well predictive of treatment response (p < 0.001).
CRP and NLR are independent indicators for survival in HCC patients, reflecting tumor burden and hepatic reserve. Their role in predicting tumor response and survival is more enhanced when used in combination. This study suggests that CRP and NLR are important prognostic biomarkers for HCC.
BMC Cancer 01/2013; 13:78. · 3.01 Impact Factor
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ABSTRACT: The development of hepatocellular carcinoma (HCC) is often associated with chronic inflammation, suggesting a strong relationship between inflammation and carcinogenesis. This study evaluated the prognostic values of inflammatory and T-helper (Th) cytokines in the clinical outcome and survival of HCC. The study included 110 patients with HCC undergoing loco-regional therapy and 24 healthy controls. Five Th1/Th2 cytokines and C-reactive protein (CRP) were quantified before and after loco-regional treatment, using enzyme-linked immunosorbent assays. Levels of CRP, interleukin (IL)-4, and IL-6 were higher in patients with HCC than those in healthy subjects. Tumor characteristics, Child-Pugh class, and CRP, IL-6, and IL-10 levels were associated with HCC survival (all P<0.05). With multivariate analysis, higher IL-6 levels were identified as the independent cytokine for shorter survival (P=0.010). Higher CRP and IL-6 levels correlated well with larger tumor size, poor Child-Pugh function, and shorter survival, with a significant inter-correlation (r=0.667). On serial measurements, the association of CRP with tumor response was stronger than that of α-fetoprotein or other cytokines. IL-6 and CRP are strong inflammatory indicators predictive of outcome in patients with HCC receiving loco-regional therapy. This study suggests that inflammatory activation of the IL-6/CRP network may be a potential therapeutic target and biomarker for HCC.
Cytokine 08/2012; · 3.02 Impact Factor
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ABSTRACT: We report the epitaxial growth of sol–gel TiO2 films by using ion-irradiation enhanced synthesis. Our present study shows that the ion-beam process can provide highly crystalline
TiO2 even at 350°C. Nuclear energy deposition at amorphous/crystalline interface plays a dominant role in the epitaxial growth
of the films at the reduced temperature via a defect-migration mechanism. In addition, the ion irradiation allows for increasing
the film density by balancing the crystallization rate and the escape rate of organic components.
Applied Physics A 05/2012; 103(1):179-184. · 1.63 Impact Factor
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ABSTRACT: Ultra fine rutile powders (below 50 nm) were prepared via the sol-gel process and bulk type TiO2 specimens were fabricated using spark plasma sintering (SPS). The TiO2 specimen sintered at a low temperature (720∘C) exhibited a highly relative density (97%) and a nano-sized grain structure (200 nm). Dielectric properties of spark plasma
sintered TiO2 specimens including dielectric constants (k) and losses (tan δ) were measured. The TiO2 specimen, obtained by SPS, showed a high dielectric constant (∼780) and a low tan δ (∼0.005), and a relaxation behavior at 1 MHz. After the subsequent annealing process of the TiO2 specimen in O2 flow, the dielectric constants remarkably decreased (k = 100s). These dielectric properties of nanocrystalline TiO2 specimens prepared by SPS were discussed in terms of space charges produced by the reduction of Ti4+ ions and crystallographic orientations of grains.
Journal of Electroceramics 05/2012; 17(2):913-917. · 1.19 Impact Factor
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ABSTRACT: Amorphous calcium phosphate was precipitated at 20°C from highly supersaturated solutions having compositions of 1.5≤Ca/P≤2.0
at a pH=11. The phase evolution and morphological changes in precipitates as a function of aging time were investigated using
XRD and TEM analyses. Higher Ca/P molar ratio of the starting solution resulted in faster crystallization to hydroxyapatite.
Shorter induction times for crystallization were attributed to smaller particle sizes of the initially precipitated ACP as
well as to the Ca-rich environment. Nucleation of the hydroxyapatite phase was suggested to be a major mechanism of crystallization,
which was supported by the observation that no considerable growth of hydroxyapatite occurred during further aging. The increase
in the number of HAp nuclei was accompanied by a size reduction of particles of amorphous phase.
Metals and Materials International 04/2012; 10(2):171-175. · 1.18 Impact Factor
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ABSTRACT: TiO2 dye-sensitized solar cells (DSSCs) coated with various oxide layers were fabricated via a screen printing method and the
effects of the oxide layers on the photovoltaic properties were systematically investigated. The open circuit voltage (V
oc) was closely dependent to the conduction band (CB) edge position and the band gap energy (E
g) of the oxide layers, while the short circuit current density (J
sc) was related to the iso-electric point (IEP). V
oc showed an increasing behavior with the CB edge position of the oxide layers, which could be explained by the blocking effect
of the insulating layers. Although J
sc was basically proportional to the IEP and the resulting dye adsorption, there were other factors like the resistance of oxide
layers. The cell efficiency could be enhanced by 60% when the cells were coated with the oxide layers of high E
g and IEP.
Journal of Electroceramics 04/2012; 23(2):422-425. · 1.19 Impact Factor
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ABSTRACT: Zn(2)SnO(4) nanoparticles (NPs) with a narrow size distribution were synthesized by a simple hydrothermal route by controlling the crystallization process. The average size of NPs was 8 nm, and this was attributed to the formation of a hydroxy carbonate compound as an intermediate phase, which was demonstrated by the structural and elemental analyses. The fine size and visible-transparency of the synthesized NPs enabled the fabrication of transparent films for efficient photoelectrochemical devices. In particular, we demonstrated dye-sensitized solar cells (DSSCs) employing these transparent Zn(2)SnO(4) photoelectrodes with a high energy conversion efficiency of 4.7%, which is mainly due to an improvement of light harvesting property.
Nanoscale 11/2011; 4(2):557-62. · 5.91 Impact Factor
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ABSTRACT: Cross-sectional studies have reported inconsistent findings on whether the risk of metabolic syndrome is high among cancer survivors. We conducted a meta-analysis of cross-sectional studies.
We searched MEDLINE (PubMed) and EMBASE in April 2010. Two evaluators independently reviewed and selected articles, based on pre-determined selection criteria.
Out of 257 articles meeting our initial criteria, 9 cross-sectional studies, which involved 6763 participants (1762 cases and 5001 controls) were included in the final analysis. Compared with the healthy control groups, the cancer survivors were at an increased risk of metabolic syndrome, in the random-effects meta-analysis of all 9 cross-sectional studies (OR=1.84; 95% CI=1.14-2.97; I(2)=80.5). In the subgroup meta-analysis by cancer type, a significant positive association was observed for hematologic malignancies, including ALL (acute lymphoblastic leukemia), AML (acute myelogenous leukemia), NHL (non-Hodgkin's lymphoma), and CML (chronic myelogenous leukemia) (OR=1.94; 95% CI=1.06-3.55; I(2)=68.1%), whereas no significant association was found for non-hematologic malignancies, including testicular tumor, prostate cancer, sarcoma, and epithelial ovarian cancer.
Our meta-analyses of cross-sectional studies found that adult cancer survivors with hematologic malignancies were at an increased risk of metabolic syndrome.
Diabetes research and clinical practice 11/2011; 95(2):275-82. · 2.16 Impact Factor
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Seung Min Jung,
Jeong Won Jang,
Chan Ran You,
Sun Hong Yoo,
Jung Hyun Kwon,
Si Hyun Bae,
Jong Young Choi,
Seung Kew Yoon,
Kyu Won Chung,
Chul Seung Kay, Hyun Suk Jung
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ABSTRACT: There has been little information about the long-term outcome and prognostic factors in patients with hepatocellular carcinoma (HCC) and extrahepatic metastases. The purpose of this study was to investigate the clinical factors affecting survival after extrahepatic metastasis and to determine the survival benefit of controlling intrahepatic HCC.
Between 2004 and 2009, a total of 240 consecutive patients with HCC and extrahepatic metastasis were recruited. Based on tumor extent, performance, and hepatic function, the patients underwent locoregional and/or systemic treatments. The treatment response of the intrahepatic tumor after extrahepatic metastasis and other prognostic parameters were analyzed retrospectively.
During the mean follow up of 276 days, 222 patients died; the median survival time was 146 days. Multivariate analysis revealed that Child-Pugh class A, smaller hepatic tumor size, absence of portal venous invasion, single metastatic organ involvement, and objective treatment response of the intrahepatic tumor were the favorable prognostic factors for survival. Of the 183 evaluable patients, 24 achieved complete or partial response for intrahepatic tumors after treatment. The overall survival for the 24 responders was significantly improved, with a median of 521 days, as compared to 170 days for the remaining 159 patients without objective tumor response. The leading cause of death was progressive intrahepatic tumor.
Intrahepatic tumor status and hepatic reserve are among the significant predictors of survival in patients with HCC and extrahepatic metastases. This study indicates that even in patients with metastases from advanced HCC, therapeutic approaches to control intrahepatic tumors are important in improving patient survival.
Journal of Gastroenterology and Hepatology 09/2011; 27(4):684-9. · 2.87 Impact Factor
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Laser Physics Review 04/2011; 1(3):415 - 421.
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ABSTRACT: In order to increase biocompatibility, many dental implants have been studied by immobilization of biomolecules on biomaterials. We used l-3,4-dihydroxyphenylalanine (L-DOPA) as a biomolecule for surface-modified titanium. Water contact angles of nontreated titanium discs (negative control), etched titanium discs (positive control), and titanium discs treated with L-DOPA following the etching process (experimental group) were 82.4 ± 5.7°, 67.1 ± 0.56°, and 44.15 ± 0.91°, respectively. Using atomic force microscopy images, we were able to find L-DOPA, which adhered to the titanium surface. The number of human bone marrow mesenchymal stem cells (BM-MSCs) in the experimental group was much higher than that of cells in any other group. Quantification values of amine groups in the positive control and experimental groups were approximately 3 and 7.5 µg, respectively. Therefore, findings from our research suggested the possibility of a causal link between increased L-DOPA content and cell proliferation in BM-MSCs. Moreover, coating of the discs with L-DOPA can result in greater hydrophilicity of the titanium surface and enhancement of cell adhesion and mitochondrial activity.
Journal of Biomaterials Applications 02/2011; 27(2):143-52. · 2.08 Impact Factor
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ABSTRACT: Ag-based oxides, Ag2M2O7 (M=Mo, W) with a triclinic structure, were prepared using a conventional solid-state reaction method, and their band structures and photocatalytic properties were investigated. From the electronic band structure calculations, Ag2Mo2O7 had an indirect band gap of 2.65 eV, whereas Ag2W2O7 had a direct band gap of 3.18 eV. Moreover, the calculated electron affinities were 4.75 eV for Ag2Mo2O7 and 4.62 eV for Ag2W2O7. The smaller band gap and higher electron affinity of Ag2Mo2O7 than those of Ag2W2O7 originated from the contribution of the unoccupied Mo 4d orbital to the conduction band, which was positioned at a lower energy level than the W 5d orbital. The effects of the different band structure characteristics in Ag2M2O7 (M=Mo, W) on the photocatalytic activity were investigated by the degradation of a Rhodamine B dye solution under visible light irradiation. The results showed that the photocatalytic activity of Ag2Mo2O7 was much higher than that of Ag2W2O7 and comparable with a well-known WO3 powder. The higher photocatalytic property of Ag2Mo2O7 was attributed to its higher optical absorption ability and lower charge recombination rate.
Journal of the American Ceramic Society 11/2010; 93(11):3867 - 3872. · 2.27 Impact Factor
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ABSTRACT: We present dye-sensitized solar cells (DSSCs) employing a thermally and chemically stable Nb-doped TiO2 (NTO)/Al-doped ZnO (AZO) multilayer transparent conducting oxide (TCO) thin film. The NTO overlayer was found to block oxygen diffusion into AZO during the air-annealing process for the fabrication process of the DSSCs, thereby exhibiting good thermal stability in electrical conductivity of the multilayer TCO. Moreover, the NTO overlayer suppressed the formation of Zn2+-dye aggregates at the surface of the AZO. The DSSC employing this multilayer TCO showed a photon to electron conversion efficiency of 3.8% compared to 1.9% for the cell employing the AZO single layer. The optical transmittance and charge transport properties that were measured using electrochemical impedance spectroscopy demonstrate that NTO/AZO is a promising TCO for large scale DSSCs.
07/2010;
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Sangwook Lee,
In-Sun Cho,
Ji Hae Lee,
Dong Hoe Kim,
Dong Wook Kim,
Jin Young Kim,
Hyunho Shin,
Jung-Kun Lee, Hyun Suk Jung,
Nam-Gyu Park,
Kyungkon Kim,
Min Jae Ko,
Kug Sun Hong
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ABSTRACT: The performance of dye-sensitized solar cells (DSSCs) consisting of anatase TiO2 nanoparticles that were synthesized via a two-step sol−gel process was investigated using electron transport and optical characterizations. Spherical nanoparticles with the average diameter of 20 nm, elongated nanorods with an aspect ratio (AR) of 5, and nanowires with AR = 10 were synthesized. The synthesized nanoparticles possess narrow size distribution, high crystallinity, and negligible surface defects and residual organics, which is very suitable for achieving highly efficient photovoltaic devices. The effect of particle size distribution on the performance of DSSC was characterized by comparing the synthesized TiO2 nanoparticles and commercial TiO2 nanoparticles (P25). In comparison with P25, the two-step sol−gel-grown nanoparticles significantly improved the photovoltaic conversion efficiency by 32.5%, because of a larger specific surface area, higher electrolyte penetration ability, and lower optical reflectance. Therefore, the photoelectrode of the two-step sol−gel-derived TiO2 nanoparticles enhanced the adsorption of dye sensitizers (N719), promotes the transfer of photogenerated carriers, and decreases the ratio of reflected solar spectrum that is not harnessed. As a result, the energy conversion efficiency of DSSCs increased to 6.72% without the use of a scattering layer and coadsorbants. We also investigated the effect of aspect ratio of TiO2 particles on photovoltaic characteristic. An increase in the aspect ratio of the synthesized nanomaterials resulted in an increase in carrier lifetime. A decrease in the density of grain boundaries suppresses the trapping of carriers and the subsequent recombination of electron−hole pairs. This study demonstrates that the two-step sol−gel-derived nanomaterials provide a way to achieve appreciable efficiency of photoconversion devices.
Chemistry of Materials. 02/2010; 22(6).
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ABSTRACT: The noble synthesis method for hydroxyapatite (HAp) nanoparticles was exploited using a fairly simple reaction of Ca(OH)(2) and H(3)PO(4), which does not generate residual harmful anions and consequently does not need an additional washing process. HAp nanoparticles were found to yield from dicalcium phosphate dehydrate (DCPD) as the only intermediate phase, which was monitored by in situ observation study using X-ray diffraction (XRD), Fourier transform infrared (FT-IR), (1)H and (31)P magic-angle spinning (MAS) NMR. Furthermore, we found that the phase evolution of HAp was preceded by heteronucleation of HAp onto the DCPD surface. The combination of scanning electron microscopy (SEM) and inductively coupled plasma atomic emission spectroscopy (ICP-ES) analysis gave more information on the HAp crystallization process, which was found to be retarded by the residual Ca(OH)(2) and slow diffusion process of Ca ions into the interface between HAp and DCPD. These results demonstrate that the synthesis of pure HAp nanoparticles with high throughput can be achieved by controlling the residual Ca(OH)(2) and diffusion process of Ca ions.
Langmuir 10/2009; 26(1):384-8. · 4.19 Impact Factor
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ABSTRACT: By carbothermally reducing a TiO2 core–sucrose shell precursor, titanium carbide mesoporous nanoparticles with a very high specific surface area (147 m2/g at 1500°C) have been prepared. The high specific surface area results from the mesoporous nature of the produced nanoparticles with two types of pores: the one with a pore diameter of about 20 nm and the other with <4 nm.
Journal of the American Ceramic Society 09/2009; 92(11):2512 - 2516. · 2.27 Impact Factor
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ABSTRACT: We fabricated composite fibrous scaffolds from blends of poly(lactide-co-glycolide) (PLGA) and nano-sized hydroxyapatite (HA) via electrospinning. SEM-EDX and AFM analysis demonstrated that HA was homogeneously dispersed in the nanofibers, and the roughness increased along with the amount of incorporated HA. When hMSCs were cultured on these PLGA/HA composite nanofibers, we found that incorporation of HA on the nanofibers did not affect cell viability whereas increased ALP activity and expression of osteogenic genes as well as the calcium mineralization of hMSCs. Our results indicate that the composite nanofibers can be offered as a potential bone regenerative biomaterial for stem cell based therapies.
Macromolecular Bioscience 09/2009; 10(2):173-82. · 3.89 Impact Factor
