혼합원자가 Sr_(1+x)La_(2-x)Fe_2O_(7-y) 훼라이트의 비화학양론 : 그 구조와 물리적 성질 Structure and Physical Properties

여철현,이성주,Grenier, Jean Claude 연세대학교 자연과학연구소 1985 學術論文集 Vol.14 No.-

Sr_(1+x)La_(2-x)Fe_2O_(7-y)계의 분말시료는 SrCO_3, La_2O_3및 Fe(NO_3)_3·9H_2O의 정량적 혼합물을 1350℃에서 24시간 가열하여 제조하였다. 이 분말시료를 펠�꼭�만들어 1450℃에서 24시간 동안 소결시켰다. 이 고용체의 결정구조는 x=0.0, 1.5, 1.7과 2.0인 경우는 정방정계였고, x=0.2, 0.5, 0.7, 1.0및 1.2인 경우는 사방정계였다. 각 계에 있어서 값이 증가할수록 격자체적이 감소함을 X-선 회절분석을 통하여 확인하였다. Mo¨ssbauer 스펙트라는 298K에서 측정하여 Fe^4+이온(δ=-0.24mm/sec)과 Fe^3+이온(δ=-0.23mm/sec)의 혼합원자가 상태를 확인하였다. 이 계의 Fe^4+이온과 Fe^3+이온의 혼합원자가 상태는 Mohr염 분석을 통하여 정량적으로 분석하였다. 비화학양론적 조성 y는 0.00에서 0.66사이의 값을 나타내었다. 시료의 전기전도도는 -100~140℃온도 범위에서 10^-9~1ohm^-1cm^-1의 반도체 영역에서 변하였다. 전기전도도의 활성화에너지는 0.47~0.14eV사이의 값을 나타내었다. 자기측정은 80K에서 1273K사이의 온도범위에서 실시하여 Ne´el온도는 Sr_3Fe_2O_6.90의 경우 130K 이었고, 그 값은 X값이 감소함에 따라 증가하였다. The powder samples of the Sr_(1+x)La_(2-x)Fe_2O_(7-y) system are prepared from stoichiometric mixtures of SrCO_3, La_2O_3, and Fe(NO_3)_3·9H_2O by heating at 1350℃ for 24 hours. The pellet samples are sintered at 1450℃ for 24 hours. The crystallographic structures of the solid solutions of x=0.0, 1.5, 1.7 and 2.0 are tetragonal systems and those of x=0.2, 0.5, 0.7, 1.0 and 1.2 are orthorhombic systems. In each systems, X-ray diffraction analysis reveals that the unit cell volume decreases when the x value is increased. Mo¨ssbauer spectra measured at 298K indicates that isomer shift of iron (Ⅳ) in x=2.0 is-0.24mm/sec and that of iron (Ⅲ) is 0.23 mm/sec. The mixed valency state at two kinds of Fe ion in the solid solutions is quantitatively analyzed by the Mohr salt titration method. The value of nonstoichiometric ratio y is varied from 0.00 to 0.66. Electrical conductivities of this systems are measured in a temperature range of -100 to 140℃. The conductivity values are vared from about 10^-9 to 1 ohm^-1 cm^-1 within semiconductivity range. Activation energies of electrical conductivity are varied from 0.47 to 0.14 eV. Magnetic mesurement indicates that Ne´el temerature is 130K in Sr_3Fe_2O_6.90 and increases when the x value is decreases.

The Use of Parathyroid 4D-MRI in Localizing Ectopic Parathyroid Glands in Renal Hyperparathyroidism

Coste Marine,Lin Ann,Grenier John-Paul,Owen Randall,Pawha Puneet S,Taye Aida 대한내분비외과학회 2023 The Koreran journal of Endocrine Surgery Vol.23 No.3

Renal hyperparathyroidism (RHPT), seen in the setting of end stage renal disease (ESRD) is associated with four gland hyperplasia. If refractory to medical management, patients are referred for surgical evaluation for parathyroidectomy. Ectopic parathyroid glands are more common in patients with RHPT and can be found in 26%–46% of patients, sometimes representing a diagnostic imaging challenge. If not accurately distinguished on imaging, they may not be found during neck exploration, which could result in recurrent disease or failure to obtain surgical cure. Different imaging modalities such as ultrasound, 99m-technetium sestamibi scan, or dynamic contrast-enhanced parathyroid computed tomography scan are available to attempt localization of parathyroid glands prior to surgery to help direct surgical exploration. More recently, dynamic, contrast-enhanced parathyroid magnetic resonance imaging (4D-MRI) has been shown to be a useful alternative imaging modality, particularly in patients with ESRD avoiding the use of iodinated contrast. Here we report two cases of ectopic parathyroid glands detected using 4D-MRI in the setting of parathyroidectomy for RHPT. Patient A is a 35-year-old female with a history of ESRD secondary to nephrotic syndrome whose 4th parathyroid gland was identified on 4D-MRI in the right inferior pole of the thyroid. Patient B is a 42-year-old male with a history of ESRD secondary to membranous nephropathy who had a parathyroid lesion identified on 4D-MRI near the left common carotid artery. In both cases, 4D-MRI proved to be a useful tool for localization of the missing parathyroid gland.

Histological Method to Study the Effect of Shear Stress on Cell Proliferation and Tissue Morphology in a Bioreactor

Morgan Chabanon,Hervé Duval,Jérôme Grenier,Claire Beauchesne,Benoit Goyeau,Bertrand David 한국조직공학과 재생의학회 2019 조직공학과 재생의학 Vol.16 No.3

BACKGROUND: Tissue engineering represents a promising approach for the production of bone substitutes. The use of perfusion bioreactors for the culture of bone-forming cells on a three-dimensional porous scaffold resolves mass transport limitations and provides mechanical stimuli. Despite the recent and important development of bioreactors for tissue engineering, the underlying mechanisms leading to the production of bone substitutes remain poorly understood. METHODS: In order to study cell proliferation in a perfusion bioreactor, we propose a simplified experimental set-up using an impermeable scaffold model made of 2 mm diameter glass beads on which mechanosensitive cells, NIH-3T3 fibroblasts are cultured for up to 3 weeks under 10 mL/min culture medium flow. A methodology combining histological procedure, image analysis and analytical calculations allows the description and quantification of cell proliferation and tissue production in relation to the mean wall shear stress within the bioreactor. RESULTS: Results show a massive expansion of the cell phase after 3 weeks in bioreactor compared to static control. A scenario of cell proliferation within the three-dimensional bioreactor porosity over the 3 weeks of culture is proposed pointing out the essential role of the contact points between adjacent beads. Calculations indicate that the mean wall shear stress experienced by the cells changes with culture time, from about 50 mPa at the beginning of the experiment to about 100 mPa after 3 weeks. CONCLUSION: We anticipate that our results will help the development and calibration of predictive models, which rely on estimates and morphological description of cell proliferation under shear stress.

Antibacterial, Antiadherence, Antiprotease, and Anti-Inflammatory Activities of Various Tea Extracts: Potential Benefits for Periodontal Diseases

Lei Zhao,Vu Dang La,Daniel Grenier 한국식품영양과학회 2013 Journal of medicinal food Vol.16 No.5

Porphyromonas gingivalis is a key etiologic agent of chronic periodontitis. This Gram-negative anaerobic bacterium produces several virulence factors and can induce a host inflammatory response that contributes to periodontal disease. In the present study, we investigated green tea, white tea, oolong tea, and black tea extracts with a high polyphenol content for their effects on (i) the growth and adherence of P. gingivalis, (ii) the activity of host and bacterial proteases, and (iii) cytokine secretion by oral epithelial cells. All the tea extracts inhibited the growth of P. gingivalis (minimal inhibitory concentrations ranging from 200 to 500 μg/mL; minimal bactericidal concentrations=500 μg/mL). In addition, they dose dependently reduced the adherence of P. gingivalis to oral epithelial cells. Tea extracts also inhibited the catalytic activity of matrix metalloproteinase (MMP)-9, neutrophil elastase, and P. gingivalis collagenase. Lastly, the tea extracts dose dependently inhibited the secretion of interleukin (IL)-6, IL-8, and chemokine (C-C motif) ligand 5 (CCL-5) by P. gingivalis–stimulated oral epithelial cells. No marked differences in the various effects were observed among the four tea extracts. Extracts from green tea, white tea, oolong tea, and black tea show promise for controlling periodontal disease by their capacity to interfere with P. gingivalis growth and virulence properties, host destructive enzymes, and inflammatory mediator secretion. Such extracts may be incorporated to oral hygiene products or locally delivered into diseased periodontal sites.

Design of PM Motor Drive Course and DSP Based Robot Traction System Laboratory

Yousfi, Driss,Belkouch, Said,Ouahman, Abdellah Ait,Grenier, Damien,Dehez, Bruno,Richard, Eric The Korean Institute of Power Electronics 2010 JOURNAL OF POWER ELECTRONICS Vol.10 No.6

This paper presents a part of North Africa/Europe collaboration results in education to develop project-oriented courses in power electronics and motor drive field. The course aims to teach Permanent Magnet motor drives close to a real world project of significant size and depth so as to be motivational, namely mobile robot project. Particular skills, student will acquire, are those relative to the detailed design and implementation of PM motor controllers in DSP based rapid prototyping environment. Simulation work is completed using graphical modeling tools in Simulink/Plecs, while real-time implementation is achieved by means of eZdspF2812 board and Simulink/TI C2000 Embedded Target tools. This flexible development environment fit the robot traction system very well and provides exactly the functionality necessary for an efficient PM motor drives teaching as demonstrated by a set of simulation and experiments.

Design of PM Motor Drive Course and DSP Based Robot Traction System Laboratory

Driss Yousfi,Said Belkouch,Abdellah Ait Ouahman,Damien Grenier,Bruno Dehez,Eric Richard 전력전자학회 2010 JOURNAL OF POWER ELECTRONICS Vol.10 No.6

This paper presents a part of North Africa/Europe collaboration results in education to develop project-oriented courses in power electronics and motor drive field. The course aims to teach Permanent Magnet motor drives close to a real world project of significant size and depth so as to be motivational, namely mobile robot project. Particular skills, student will acquire, are those relative to the detailed design and implementation of PM motor controllers in DSP based rapid prototyping environment. Simulation work is completed using graphical modeling tools in Simulink/Plecs, while real-time implementation is achieved by means of eZdspF2812 board and Simulink/TI C2000 Embedded Target tools. This flexible development environment fit the robot traction system very well and provides exactly the functionality necessary for an efficient PM motor drives teaching as demonstrated by a set of simulation and experiments.

Anthocyanin-Rich Black Currant Extract and Cyanidin-3-O-Glucoside Have Cytoprotective and Anti-Inflammatory Properties

Jacynthe Desjardins,Shinichi Tanabe,Chantal Bergeron,Stefan Gafner,Daniel Grenier 한국식품영양과학회 2012 Journal of medicinal food Vol.15 No.12

Periodontal diseases are a group of multifactorial polymicrobial infections characterized by a progressive inflammatory destruction of the periodontium. Flavonoids, including anthocyanins, are receiving increasing attention because of their promising human health benefits. The aim of our study was to investigate the effect of anthocyanins, pure or as part of a standardized black currant extract, on nicotine-induced cytotoxicity and lipopolysaccharide (LPS)-induced inflammatory responses in human cells. Using a colorimetric assay that measures cell viability, it was found that a pretreatment with an anthocyanin-rich black currant extract or cyanidin-3-O-glucoside neutralized the cytotoxic effect of nicotine on epithelial cells and fibroblasts in a dose-dependent manner. The black currant extract and cyanidin-3-O-glucoside also inhibited the LPSinduced secretion of interleukin-6 by human macrophages. The results of the present study suggest that black currant extract and cyanidin-3-O-glucoside may be promising candidates for the development of novel therapies to prevent and/or to treat smoking-related periodontal diseases.

Anti-Inflammatory and Wound Healing Potential of Citrus Auraptene

Vu Dang La,Lei Zhao,Francesco Epifano,Salvatore Genovese,Daniel Grenier 한국식품영양과학회 2013 Journal of medicinal food Vol.16 No.10

Auraptene is the most abundant naturally occurring geranyloxycoumarin. It is primarily isolated from plants in the Rutaceae family, many of which, like citrus fruits, are used as food in many countries. Auraptene is a biologically active secondary metabolite with valuable properties. The aim of our study was to identify novel properties of auraptene with potential for managing periodontal diseases, an inflammatory disease of bacterial origin affecting the tissues surrounding and supporting the teeth. In vitro assays showed that auraptene decreased, in a dose-dependent manner, the secretion of matrix metalloproteinase 2 as well as key inflammatory mediators, including interleukin-6 (IL-6), IL-8, and chemokine (C-C motif) ligand-5 secreted by Aggregatibacter actinomycetemcomitans lipopolysaccharide-stimulated oral epithelial cells. Using gingival fibroblasts, auraptene showed a significant (P < .05) wound healing effect by its capacity to increase cell migration. In conclusion, auraptene shows promise for promoting wound healing and controlling periodontal diseases through its capacity to interfere with inflammatory mediator secretion.

Pyrroloindacenodithiophene containing polymers for organic field effect transistors and organic photovoltaics

Donaghey, Jenny E.,Ashraf, Raja Shahid,Kim, Youngju,Huang, Zheng Gang,Nielsen, Christian B.,Zhang, Weimin,Schroeder, Bob,Grenier, Christophe R. G.,Brown, Christopher T.,D'Angelo, Pasquale,Smith, Jerem Royal Society of Chemistry 2011 Journal of materials chemistry Vol.21 No.46

<P>The synthesis of the novel electron-rich pyrroloindacenodithiophene (NIDT) unit is reported. Stille copolymerization of the distannylated NIDT unit, with the electron-deficient dibrominated benzothiadiazole (BT), difluorobenzothiadiazole (ffBT), thienopyrrolodione (TPD) and 1,1′-bithienopyrrolodione (biTPD) units afforded a series of low band gap semiconducting polymers. Initial testing shows promise for the use of these materials as p-type semiconductors in organic field effect transistors (OFETs) with mobilities as high as 0.07 cm<SUP>2</SUP>V<SUP>−1</SUP>s<SUP>−1</SUP> being measured. These materials have also been tested as the donor polymer in polymer/fullerene bulk heterojunction organic photovoltaics (OPVs) giving maximum efficiencies of 2.5%.</P> <P>Graphic Abstract</P><P>Four copolymers synthesized with a novel unit, pyrroloindacenoditiophene, were tested in OFET (μ<SUB>max</SUB> 0.07 cmV<SUP>−1</SUP>s<SUP>−1</SUP>) and OPV (η<SUB>max</SUB> 2.5%) devices. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c1jm13428k'> </P>

Inter- and Intra-granular Critical Current in $Bi_{1.4}Pb_{0.6}Sr_2Ca_2Cu_{3.6}O_x$ Superconducting Oxide

Choy, Jin-Ho,Kim, Seung-Joo,Park, J.C.,Frohlich, K.,Dordor, P.,Grenier, J.C. Korean Chemical Society 1990 Bulletin of the Korean Chemical Society Vol.11 No.6

A.c. susceptibility for $Bi_{1.4}Pb_{0.6}Sr_2Ca_2Cu_{3.6}O_x$ superconductor is measured as a function of temperature at different value of a.c. magnetic field amplitude. Two transition steps are attributed to the intergranular and intragranular properties. Based on Bean's critical state model, intergranular critical current density, $J_c^{gb}$ (11 $A/cm^2$ at 77 K) and intragranular critical current density, $J_c^g (7{\times}10^3\;A/cm^2$ at 100 K) are estimated. The low values of $J_c^{gb}$and $J_c^g$ reflect a poor nature of coupling between grains and the low pinning force density of intragrain in $Bi_{1.4}Pb_{0.6}Sr_2Ca_2Cu_{3.6}O_x$ superconductor.