https://pubs.kist.re.kr/handle/123456789/75370 2026-02-12T01:24:33Z 2026-02-12T01:24:33Z Sharma, A. Varshney, M. Kang, S. Baik, J. Ha, T.-K. Chae, K.-H. Kumar, S. Shin, H.-J. https://pubs.kist.re.kr/handle/201004/124603 2024-04-25T04:33:51Z 2016-01-01T00:00:00Z

Title: Electronic structure study and dielectric properties of amorphous ZrO2 and HfO2 Authors: Sharma, A.; Varshney, M.; Kang, S.; Baik, J.; Ha, T.-K.; Chae, K.-H.; Kumar, S.; Shin, H.-J. Abstract: ZrO2 and HfO2 powder samples were prepared by using the chemical precipitation method and subsequent annealing. Crystal structure, local electronic structure and dielectric constant of amorphous and crystalline powders of ZrO2 and HfO2 have been examined using the synchrotron X-ray diffraction, O K-edge X-ray absorption spectroscopy, Zr 3d and Hf 4f core-level X-ray photoelectron spectroscopy and temperature dependent dielectric measurements, respectively. Amorphous ZrO2 and HfO2 powders exhibit a local tetragonal structure, with mixed +3 and +4 valence states of Zr and Hf ions, and demonstrated the high dielectric performance. After the heat treatment, the tetragonal phase transforms into the monoclinic phase with dominant +4 valence state of Zr and Hf ions and the larger sized ZrO2 and HfO2 nanoparticles exhibited low dielectric constant. The manifestation of high dielectric constants in the amorphous ZrO2 and HfO2 samples is because of the hopping of electrons between the Zr+3-Zr+4 and Hf+3-Hf+4 networks. Copyright ？ 2016 VBRI Press.

2016-01-01T00:00:00Z Kim, Sang Jun Kim, Ji Eun Kim, Su Hee Kim, Sun Jeong Jeon, Su Jeong Kim, Soo Hyun Jung, Youngmee https://pubs.kist.re.kr/handle/201004/124602 2024-04-25T04:33:50Z 2016-01-01T00:00:00Z

Title: Therapeutic effects of neuropeptide substance P coupled with self-assembled peptide nanofibers on the progression of osteoarthritis in a rat model Authors: Kim, Sang Jun; Kim, Ji Eun; Kim, Su Hee; Kim, Sun Jeong; Jeon, Su Jeong; Kim, Soo Hyun; Jung, Youngmee Abstract: Osteoarthritis (OA) is a progressively degenerative disease that is accompanied by articular cartilage deterioration, sclerosis of the underlying bone and ultimately joint destruction. Although therapeutic medicine and surgical treatment are done to alleviate the symptoms of OA, it is difficult to restore normal cartilage function. Mesenchymal stem cell (MSC) transplantation is one of the therapeutic trials for treating OA due to its potential, and many researchers have recently reported on the effects of MSCs associated with OA therapy. However, cell transplantation has limitations including low stem cell survival rates, limited stem cell sources and long-term ex vivo culturing. In this study, we evaluated the efficacy of neuropeptide substance P coupled with self-assembled peptide hydrogels in a rat knee model to prevent OA by mobilizing endogenous MSCs to the defect site. To assess the effect of the optimal concentration of SP, varying concentrations of bioactive peptides (substance P (SP) with self-assembled peptide (SAP)) were used to treat OA. OA was induced by unilateral anterior cruciate and medial collateral ligament transection of the knee joints. Forty rats were randomly allocated into 5 groups: SAP-0.5SP (17.5 mu g of SP), SAP-SP group (35 mu g of SP), SAP-2SP group (70 mu g of SP), SAP-SP-MSC group, and control group. At 2 weeks post-surgical induction of OA, each mixture was injected into the joint cavity of the left knee. Histologic examination, immunofluorescence staining, quantitative real time-polymerase chain reaction and micro-computed tomography analysis were done at 6 weeks post-surgical induction. As shown by our results, the SAP-SP hydrogel accelerated tissue regeneration by anti-inflammatory modulation shown by an anti-inflammation test using dot-blot in vitro. Additionally, the treatment of OA in the SAP-SP group showed markedly improved cartilage regeneration through the recruitment of MSCs. Thus, these cells could be infiltrating into the defect site for the regeneration of OA defects. In addition, from the behavioral studies on the rats, the number of rears significantly increased 2 and 4 weeks post-injection in all the groups. Our results show that bioactive peptides may have clinical potential for inhibiting the progression of OA as well as its treatment by recruiting autologous stem cells without cell transplantation. (C) 2015 Elsevier Ltd. All rights reserved.

2016-01-01T00:00:00Z Lee, Gi Yong Jung, Kinam Jang, Ho Seong Kyhm, Jihoon Han, Il Ki Park, Byoungnam Ju, Honglyoul Kwon, S. Joon Ko, Hyungduk https://pubs.kist.re.kr/handle/201004/124601 2024-04-25T04:33:48Z 2016-01-01T00:00:00Z

Title: Upconversion luminescence enhancement in plasmonic architecture with random assembly of metal nanodomes Authors: Lee, Gi Yong; Jung, Kinam; Jang, Ho Seong; Kyhm, Jihoon; Han, Il Ki; Park, Byoungnam; Ju, Honglyoul; Kwon, S. Joon; Ko, Hyungduk Abstract: We report an experimental study on the highly enhanced upconversion luminescence (UCL) of beta-NaYF4: Yb3+/Er3+ nanocrystals (NCs) in a plasmonic architecture. For the architecture, we designed a thin film device composed of a thin layer of NCs capped with an upper layer of a plasmonic nanodome array (pNDA) and lower substrate of a back reflector (BR). Compared to the UCL intensity observed in a glass reference substrate, the designed plasmonic architecture exhibits distinctively strong luminescence enhanced by up to 800-fold. The intensity considerably exceeds the previously reported luminescence intensity regardless of the excitation power. We elucidated a mechanism explaining the large UCL enhancement, which quantitatively analyzes the combination of plasmonic effects as well as multiple large scattering. More importantly, we provided a detailed analysis of the Ag NDA-derived and BR-assisted plasmonic effects that contribute to an increase in the radiative decay rate and an enhancement of the absorption of incident light. The present study is expected to be beneficial for designing a thin film-based plasmonic structure with a randomized metal nanostructure for high-efficiency photovoltaic devices and infrared detectors.

2016-01-01T00:00:00Z Jung, Ji-Hyun Cho, Jae-Hyoung Kim, Se-Yun https://pubs.kist.re.kr/handle/201004/124600 2024-04-25T04:33:46Z 2016-01-01T00:00:00Z

Title: Accuracy enhancement of wideband complex permittivity measured by an open-ended coaxial probe Authors: Jung, Ji-Hyun; Cho, Jae-Hyoung; Kim, Se-Yun Abstract: When the wideband complex permittivity of a liquid solution was measured by an open-ended coaxial probe, its accuracy was inherently degraded due to an inexact conversion model compared with the uncertainty of the associated vector network analyzer. In this paper, the accuracy of the converted wideband complex permittivity is evaluated indirectly and then enhanced significantly. Firstly, the measured wideband complex permittivity is fitted by a dispersive permittivity profile in the Debye formula. Secondly, the new reflection coefficients are calculated numerically by applying the dispersive permittivity profile to a 2D finite-difference time-domain model of our probe. Thirdly, the inaccuracy of the fitted complex permittivity profile is quantified indirectly by the root mean square (RMS) error of the numerically calculated reflection coefficients in comparison with the originally measured reflection coefficients. Finally, four parameters of the Debye formula involved in the initially converted complex permittivity profile were calibrated iteratively until the RMS error of the repeatedly calculated reflection coefficients could be minimized. The validity of the above calibration procedure is assured numerically for a given wideband complex permittivity profile. In the case of our actual measurement of the fabricated cancer-equivalent solution, an unknown complex permittivity profile, the RMS error of the numerically calculated reflection coefficients could be reduced from 0.0416 to 0.0093. This calibration results in both relative dielectric constant and conductivity profiles being gradually enhanced as the frequency increases up to 5000 MHz.

2016-01-01T00:00:00Z