Effects of Additives of CaO and Rare-Earth Oxides on the Sintering Behavior of AlN Ceramics

Chih-Hung Chu,Yun-Hwei Shen,Chih-Peng Lin,Shaw-Bing Wen 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.52 No.5

The effect of additives of CaO plus three different rare-earth oxides (Y, Sm and Gd, separately) on the sintering behavior of AlN ceramics has been evaluated at 1700℃ by using a MoSi2 heater and ambient atmosphere. The results of density measurements show that the atomic weight of the rare-earth element may substantially affect the apparent density of the sintered AlN specimen due to the kinetics of atomic diffusion during sintering. The optimum results of this study show that these additives are effective in obtaining an apparent density of 3.26 g/cm3 (approaching a 100 % theoretical density of AlN). The Vicker's hardness of the sintered AlN can reach a high value of 1310 kg/mm2 and an apparent density of 3.34 g/cm3. A longer soaking time of between 3 and 5 h is necessary to practically eliminate the minor oxide phases. The effect of additives of CaO plus three different rare-earth oxides (Y, Sm and Gd, separately) on the sintering behavior of AlN ceramics has been evaluated at 1700℃ by using a MoSi2 heater and ambient atmosphere. The results of density measurements show that the atomic weight of the rare-earth element may substantially affect the apparent density of the sintered AlN specimen due to the kinetics of atomic diffusion during sintering. The optimum results of this study show that these additives are effective in obtaining an apparent density of 3.26 g/cm3 (approaching a 100 % theoretical density of AlN). The Vicker's hardness of the sintered AlN can reach a high value of 1310 kg/mm2 and an apparent density of 3.34 g/cm3. A longer soaking time of between 3 and 5 h is necessary to practically eliminate the minor oxide phases.

Thermal conductivity of micro hot-pressed AlN ceramics fabricated using a conventional MoSi2 heating element furnace

Chih-Peng Lin,Chih-Hung Chu,Shaw-Bing Wen,Yun-Hwei Shen 한양대학교 세라믹연구소 2011 Journal of Ceramic Processing Research Vol.12 No.5

AlN samples doped with sub-micron Y2O3 and CaO powders as sintering additives obtained using the micro hot-pressed (MHPed) sintering method in a MoSi2 heating element furnace were investigated. The minor amounts of secondary phases were identified as Al5Y3O12, CaYAl3O7, and CaAl4O7, which are related to the low sintering temperature as well as the removal of oxygen-related defects in the system. Relative densities of over 96% of the theoretical value were obtained after sintering at 1600 oC for 8 h, indicating that an adequate amount of additives and the use of the micro hot-pressed (MHPed) sintering process help improve the densification and thermal conductivity of AlN ceramics. The high thermal conductivity of 130Wm−1K−1was attributed to the purification of the AlN lattice, the elimination of some secondary phases, and the grain boundary phase distribution.

Low temperature fabrication of (001) FePt on amorphous substrates

Yun-Chang Wu,Liang-Wei Wang,Chih-Huang Lai 한국자기학회 2007 한국자기학회 학술연구발표회 논문개요집 Vol.- No.-

Osteogenesis and Chondrogenesis of Primary Rabbit Periosteal Cells under Non-uniform 2-Axial Tensile Strain

Chih-Hao Chiu,Yun-Wen Tong,Jen-Fang Yu,Kin Fong Lei,Alvin Chao-Yu Chen 한국바이오칩학회 2020 BioChip Journal Vol.14 No.4

Periosteal cells are the major cell sources of skeletal progenitors for fracture callus. In order to promote bone repair and cartilage formation, besides the application of exogenous growth factors, physical stimulation is an alternative approach to guide cell differentiation. Investigation of appropriate conditions is essential for forming bone and cartilage. In this work, a membrane-type micro-system was developed to provide cell culture environment and cell stretching stimulation during culture course. Circular and oval culture wells were designed to respectively generate uniform and non-uniform 2-axial tensile strain for stretching primary rabbit periosteal cells. Cell orientation and differentiation were studied after cycling stretching for 2 days. The cells aligned to the stretching axis with high tensile strain in the oval culture wells; while the cells expressed random orientation in the circular culture wells. Different responses were significantly shown when the cells were respectively stimulated by uniform and non-uniform 2-axial tensile strains. On the other hand, osteogenic differentiation was shown when the cells were under either uniform or non-uniform 2-axial tensile strain. However, only non-uniform 2-axial tensile strain could induce mature osteoblasts. In addition, the result revealed chondrocytes could be differentiated only under a large and nearly single dimensional tensile strain. In summary, differentiation of the periosteal cells is highly influenced by 2-dimensional distribution of the tensile strain. This work provides some in-sights of the control of axial tensile strain for periosteal cell differentiation.

New Frontiers or the Treatment of Interstitial Cystitis/Bladder Pain Syndrome - Focused on Stem Cells, Platelet-Rich Plasma, and Low-Energy Shock Wave

Chih-Chieh Lin,Yun-Ching Huang,Wei-Chia Lee,Yao-Chi Chuang 대한배뇨장애요실금학회 2020 International Neurourology Journal Vol.24 No.3

Interstitial cystitis/bladder pain syndrome (IC/BPS), which is characterized by bladder pain and irritative voiding symptoms, is a frustrating disease without effective treatment. The cause is still largely not understood, although urothelium ischemia/hypoxia, apoptosis, denudation, and infiltration of inflammatory cells are common histopathological findings. The current uncertainty regarding the etiology and pathology of IC/BPS has a negative impact on its timely and successful treatment; therefore, the development of new treatment modalities is urgently needed. Herein, we present advances in our knowledge on this topic and review the potential application of regenerative medicine for the treatment of IC/BPS. This article provides information on the basic characteristics and clinical evidence of stem cells, platelet-rich plasma (PRP), and low-energy shock waves (LESWs) based on a literature review with a search strategy for articles related to IC/BPS, stem cells, PRP, and LESW published in MEDLINE and PubMed. Stem cells, PRP, and LESW, which modulate inflammatory processes and promote tissue repair, have been proven to improve bladder regeneration, relieve bladder pain, inhibit bladder inflammation, and increase bladder capacity in some preclinical studies. However, clinical studies are still in their infancy. Based on the mechanisms of action of stem cells, PRP, and LESW documented in many preclinical studies, the potential applications of regenerative medicine for the treatment of IC/BPS is an emerging frontier of interest. However, solid evidence from clinical studies remains to be obtained.

Hericium erinaceus Mycelium and Its Isolated Compound, Erinacine A, Ameliorate High-Fat High-Sucrose Diet-Induced Metabolic Dysfunction and Spatial Learning Deficits in Aging Mice

Yun-Chieh Tsai,Yu-Chen Lin,Chun-Chih Huang,Oliver B. Villaflores,Tzong-Yuan Wu,Shih-Ming Huang,Ting-Yu Chin 한국식품영양과학회 2019 Journal of medicinal food Vol.22 No.5

Aging and lifestyle factors, including high-sugar and high-fat diets, promote a systemic metabolic imbalance that promotes neurodegeneration. Hericium erinaceus has long been used in traditional Chinese medicine. Recently, its functional activities, such as antimetabolic dysfunction, antineuroinflammatory activities, and stimulation of nerve growth factor (NGF) synthesis, have been revealed. This study demonstrated that Hericium erinaceus mycelium (HEM) and an isolated diterpenoid derivative, erinacine A (EA), may reverse spatial learning disabilities in aging mice (15 months old) fed with a high-fat and high-sucrose diet (HFSD). Aging mice were randomly assigned to one of four treatment groups: (1) a chow diet (control), (2) an HFSD, and an HFSD supplemented with either (3) HEM or (4) EA for 18 weeks. The Morris water maze (MWM) and Y-maze were used for behavioral assessments. Both HEM- and EA-treated mice had shorter mean daily escape latencies than HFSD-treated mice in the MWM. In addition, HEM-treated mice had a slightly increased exploratory time and frequency in the novel arm in the Y-maze. Quantitative PCR revealed that both HEM- and EA-treated mice exhibited reduced messenger RNA (mRNA) expression of tumor necrosis factor-α, interleukin-1β, and HEM-treated mice exhibited increased mRNA expression of NGF and NeuN in the hippocampus. Moreover, HEM and EA also decreased body weight, abdominal fat, plasma glucose, serum and liver total cholesterol, and liver triacylglycerol. Thus, HEM may be a potential health-promoting supplement for minimizing the progression of aging and obesity-induced neurodegeneration by reducing metabolic abnormalities and neuroinflammatory cytokines and increasing neurogenesis factors.

Improving Video Transmission in Software Defined Wired and Wireless Networks using Multi-Path Transmission

Chih-Heng Ke,Yeong-Sheng Chen,Yun-Shuai Yu 한국통신학회 2017 Journal of communications and networks Vol.19 No.6

Recently, increasing attention has been paid to the studyof applying software defined networks to improve video transmission. Compared with the existing studies which focus on a wirednetwork, this study proposed a multi-path transmission mechanismfor improving the performance of transmitting videos from awired network to a wireless one in a software defined network environment. In the proposed mechanism, a mobile host could applynetwork bonding to integrate several physical or virtual wirelessnetwork modules, each of which was connected to a different accesspoint, into a combined device. Thus, multiple wireless links ofthe mobile host could be established and hence multiple transmissionpaths from the video source in the wired network to the mobilehost were derived. In addition, different amount of video packetswere allocated onto different transmission paths so as to maximizethe performance of the multi-path transmission. According to theresults of our experiments, the proposed mechanism can enhancethe performance of transmission in terms of Peak Signal to NoiseRatio (PSNR).

Downregulation of Human DAB2IP Gene Expression in Renal Cell Carcinoma Results in Resistance to Ionizing Radiation

Yun, Eun-Jin,Lin, Chun-Jung,Dang, Andrew,Hernandez, Elizabeth,Guo, Jiaming,Chen, Wei-Min,Allison, Joyce,Kim, Nathan,Kapur, Payal,Brugarolas, James,Wu, Kaijie,He, Dalin,Lai, Chih-Ho,Lin, Ho,Saha, Debab American Association for Cancer Research 2019 Clinical Cancer Research Vol.25 No.14

<P><B>Purpose:</B></P><P>Renal cell carcinoma (RCC) is known to be highly radioresistant but the mechanisms associated with radioresistance have remained elusive. We found DOC-2/DAB2 interactive protein (DAB2IP) frequently downregulated in RCC, is associated with radioresistance. In this study, we investigated the underlying mechanism regulating radioresistance by DAB2IP and developed appropriate treatment.</P><P><B>Experimental Design:</B></P><P>Several RCC lines with or without DAB2IP expression were irradiated with ionizing radiation (IR) for determining their radiosensitivities based on colony formation assay. To investigate the underlying regulatory mechanism of DAB2IP, immunoprecipitation-mass spectrometry was performed to identify DAB2IP-interactive proteins. PARP-1 expression and enzymatic activity were determined using qRT-PCR, Western blot analysis, and ELISA. <I>In vivo</I> ubiquitination assay was used to test PARP-1 degradation. Furthermore, <I>in vivo</I> mice xenograft model and patient-derived xenograft (PDX) model were used to determine the effect of combination therapy to sensitizing tumors to IR.</P><P><B>Results:</B></P><P>We notice that DAB2IP-deficient RCC cells acquire IR-resistance. Mechanistically, DAB2IP can form a complex with PARP-1 and E3 ligases that is responsible for degrading PARP-1. Indeed, elevated PARP-1 levels are associated with the IR resistance in RCC cells. Furthermore, PARP-1 inhibitor can enhance the IR response of either RCC xenograft model or PDX model.</P><P><B>Conclusions:</B></P><P>In this study, we unveil that loss of DAB2IP resulted in elevated PARP-1 protein is associated with IR-resistance in RCC. These results provide a new targeting strategy to improve the efficacy of radiotherapy of RCC.</P>

Improving Scanner Data Collection in P4-based SDN

Yun-Zhan Cai,Chih-Hao Lai,Yu-Ting Wang,Meng-Hsun Tsai 한국통신학회 2020 한국통신학회 APNOMS Vol.2020 No.09

Port scanning is a well-known behavior when a botnet searches target devices. To detect port scanning accurately, data with high discriminatory power are indispensable. Most related works, however, focus on data analysis methods but neglect storage limitations of switches, which makes their methods impractical. Therefore, we propose a new data collection method for collecting network information of port scanning in P4-based SDN named 0-replacement. Through simulations, we compare the 0-replacement method with two classic data collection methods. Results show that the 0-replacement method improves the true positive ratio by at least 25 percentage points but only consumes 0.36% memory space.

Energy dissipation of steel-polymer composite beam-column connector

Yun-Che Wang,Chih-Chin Ko 국제구조공학회 2015 Steel and Composite Structures, An International J Vol.18 No.5

The connection between a column and a beam is of particular importance to ensure the safety of civil engineering structures, such as high-rise buildings and bridges. While the connector must bear sufficient force for load transmission, increase of its ductility, toughness and damping may greatly enhance the overall safety of the structures. In this work, a composite beam-column connector is proposed and analyzed with the finite element method, including effects of elasticity, linear viscoelasticity, plasticity, as well as geometric nonlinearity. The composite connector consists of three parts: (1) soft steel; (2) polymer; and (3) conventional steel to be connected to beam and column. It is found that even in the linear range, the energy dissipation capacity of the composite connector is largely enhanced by the polymer material. Since the soft steel exhibits low yield stress and high ductility, hence under large deformation the soft steel has the plastic deformation to give rise to unique energy dissipation. With suitable geometric design, the connector may be tuned to exhibit different strengths and energy dissipation capabilities for real-world applications.