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1
Shimozuma, T., M. Yokoyama, K. Ida, Y. Takeiri, S. Kubo, S. Murakami, A. Wakasa, et al. "Improvement of Plasma Core Confinement Via Electron-Root Realization by Strongly Focused ECRH in LHD: Core Electron-Root Confinement." Fusion Science and Technology 58, no. 1 (August 2010): 38–45. http://dx.doi.org/10.13182/fst10-a10791.
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Yokoyama, M., H. Maaßberg, C. D. Beidler, V. Tribaldos, K. Ida, T. Estrada, F. Castejon, et al. "Core electron-root confinement (CERC) in helical plasmas." Nuclear Fusion 47, no. 9 (August 29, 2007): 1213–19. http://dx.doi.org/10.1088/0029-5515/47/9/018.
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Yokoyama, M., H. Maassberg, C. D. Beidler, V. Tribaldos, K. Ida, F. Castejón, T. Estrada, et al. "Common Features of Core Electron-Root Confinement in Helical Devices." Fusion Science and Technology 50, no. 3 (October 2006): 327–42. http://dx.doi.org/10.13182/fst06-a1254.
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MATSUOKA, Seikichi, Shinsuke SATAKE, Masayuki YOKOYAMA, and Arimitsu WAKASA. "Radial Electric Field Formation Including Electron Radial Drift for a Core Electron-Root Confinement (CERC) Plasma in LHD." Plasma and Fusion Research 6 (2011): 1203016. http://dx.doi.org/10.1585/pfr.6.1203016.
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Ridha, A. R. "Elastic electron scattering from 17Ne and 27P exotic nuclei." Iraqi Journal of Physics (IJP) 13, no. 28 (February 4, 2019): 68–81. http://dx.doi.org/10.30723/ijp.v13i28.244.
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The ground state proton, neutron and matter densities andcorresponding root mean square radii of unstable proton-rich 17Neand 27P exotic nuclei are studied via the framework of the twofrequencyshell model. The single particle harmonic oscillator wavefunctions are used in this model with two different oscillator sizeparameters core b and halo , b the former for the core (inner) orbitswhereas the latter for the halo (outer) orbits. Shell model calculationsfor core nucleons and for outer (halo) nucleons in exotic nuclei areperformed individually via the computer code OXBASH. Halostructure of 17Ne and 27P nuclei is confirmed. It is found that thestructure of 17Ne and 27P nuclei have 25 / 2 (1d ) and 1/ 2 2s -dominantconfigurations, respectively. Elastic electron scattering form factorsof these exotic nuclei are also studied using the plane wave Bornapproximation. Effects of the long tail behavior of the proton densitydistribution on the proton form factors of 17Ne and 27P areanalyzed. It is found that the difference between the proton formfactor of 17Ne and that of stable 20Ne (or of 27P and that of stable31P) comes from the difference in the proton density distribution ofthe last two protons (or of the last proton) in the two nuclei. It isconcluded that elastic electron scattering will be an efficient tool (inthe near future) to examine proton-halo phenomena of proton-richnuclei.
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TAKEIRI, Yasuhiko, Masayuki YOKOYAMA, Kenichi NAGAOKA, Katsumi IDA, Shin KUBO, Takashi SHIMOZUMA, Hisamichi FUNABA, et al. "Improvement of Ion Confinement in Core Electron-Root Confinement (CERC) Plasmas in Large Helical Device." Plasma and Fusion Research 3 (2008): S1031. http://dx.doi.org/10.1585/pfr.3.s1031.
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Chen, Huan, Xinyuan Zhao, Yu Qiu, Dengyou Xu, Li Cui, and Buling Wu. "The Tubular Penetration Depth and Adaption of Four Sealers: A Scanning Electron Microscopic Study." BioMed Research International 2017 (2017): 1–8. http://dx.doi.org/10.1155/2017/2946524.
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Background. The tubular penetration and adaptation of the sealer are important factors for successful root canal filling. The aim of this study was to evaluate the tubular penetration depth of four different sealers in the coronal, middle, and apical third of root canals as well as the adaptation of these sealers to root canal walls. Materials and Methods. 50 single-rooted teeth were prepared in this study. Forty-eight of them were filled with different sealers (Cortisomol, iRoot SP, AH-Plus, and RealSeal SE) and respective core filling materials. Then the specimens were sectioned and scanning electron microscopy was employed to assess the tubular penetration and adaptation of the sealers. Results. Our results demonstrated that the maximum penetration was exhibited by RealSeal SE, followed by AH-Plus, iRoot SP, and Cortisomol. As regards the adaptation property to root canal walls, AH-Plus has best adaptation capacity followed by iRoot SP, RealSeal SE, and Cortisomol. Conclusion. The tubular penetration and adaptation vary with the different sealers investigated. RealSeal SE showed the most optimal tubular penetration, whereas AH-Plus presented the best adaptation to the root canal walls.
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Dlshad, Hawar Muhamad, Aziz Hama-Raheem Fatah, and Adil Mohammed Hussain. "The Elastic and Inelastic Electron-Nucleus Scattering Form Factors for Be9 Nucleus." UHD Journal of Science and Technology 4, no. 2 (August 17, 2020): 56. http://dx.doi.org/10.21928/uhdjst.v4n2y2020.pp56-62.
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The computations of the elastic and inelastic Coulomb form factors for the electron-nucleus scattering of Beryllium nucleus Be9 have performed with Core Polarization (CP) effects including the realistic Michigan sum of Three Range Yukawa (M3Y) Interaction, and the other residual interaction which is Modified Surface Delta Interaction (MSDI). In addition to mean square root charge density and charge radii for the ground state. The perturbation theory was adopted to compute the Core Polarization by using the Harmonic Oscillators (HO) potential to calculate single-particle radial wave functions.
In the comparison between the theoretical calculations of Coulomb form factors by (MSDI) interaction, realistic (M3Y) interaction, and the experimental results that measured before, it noticed that the Coulomb form factors for the (M3Y) interaction gave a reasonable depiction of the measured data.
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Jacobs, Mark J., William M. Bugbee, and David A. Gabrielson. "Enumeration, location, and characterization of endophytic bacteria within sugar beet roots." Canadian Journal of Botany 63, no. 7 (July 1, 1985): 1262–65. http://dx.doi.org/10.1139/b85-174.
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An increased bacterial population was found in the secondary root emergence zone tissue of sugar beet roots as compared with core and peripheral tissue of the same beet. The most common bacteria in sugar beet tissue were isolated, characterized, and used to immunize New Zealand white rabbits for antibody production. The bacteria-specific immunoglobulins from the rabbit sera were incubated with sugar beet tissue. These antibody-treated tissues were then incubated with ferritin-labeled goat antirabbit immunoglobulin to assist in identifying immunoglobulin-bound bacteria within tissue samples. This procedure was useful in distinguishing bacteria from artifacts and normal cell inclusions. The location of these antibody-bound bacteria within sugar beet root tissue was identified by using scanning electron microscopy.
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Teodorovic, Nevenka, and Ivan Matovic. "Scanning electron microscopic analysis of the sealing ability of GuttaFlow and Acroseal endodontic sealers." Serbian Dental Journal 55, no. 1 (2008): 15–22. http://dx.doi.org/10.2298/sgs0801015t.
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Introduction: The sealing ability of endodontic sealers to dentinal surfaces of root canals is an important feature of these materials. Root canal sealers are necessary to seal the spaces between the dentinal walls and the obturating core material. Aim: The aim of this study was to examine the sealing ability of two endodontic sealers to dentin walls and guttapercha cones using scanning electron microscopic analysis-SEM. Materials and Methods: 24 recently extracted human single-rooted teeth were instrumented and allocated to two groups; root canals were filled with either GuttaFlow (Roeko,Germany), a new endo-sealer (group 1), or Acroseal (Septodont, France), a calcium hydroxide based sealer, (group 2). The sealing ability and adhesion properties of the sealer-dentin interface were studied using SEM. Results: The specimens filled with GuttaFlow showed smooth contact lines at the sealer-dentin interface, and this material also showed strong bonding and good adaptation to guttapercha cones. Acroseal showed good adhesion to dentin walls, and bonding surface was represented as a slightly curved contact line, with some gaps on material-dentin walls and guttapercha cones interface. Conclusion: New GuttaFlow material possesses strong sealing ability and excellent adhesion to dentin walls and guttapercha cones. Acroseal showed good bonding to dentin and slightly weaker adhesion to guttapercha cones, in comparison to GuttaFlow.
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Mohammed, Saja H. "Study of nuclear structure for carbon isotopes using local scale transformation technique in shell model." Iraqi Journal of Physics (IJP) 16, no. 39 (January 5, 2019): 103–16. http://dx.doi.org/10.30723/ijp.v16i39.108.
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This work is devoted to study the properties of the ground states such as the root-mean square ( ) proton, charge, neutron and matter radii, nuclear density distributions and elastic electron scattering charge form factors for Carbon Isotopes (9C, 12C, 13C, 15C, 16C, 17C, 19C and 22C). The calculations are based on two approaches; the first is by applying the transformed harmonic-oscillator (THO) wavefunctions in local scale transformation (LST) to all nuclear subshells for only 9C, 12C, 13C and 22C. In the second approach, the 9C, 15C, 16C, 17C and 19C isotopes are studied by dividing the whole nuclear system into two parts; the first is the compact core part and the second is the halo part. The core and halo parts are studied using the radial wave functions of HO and THO radial wavefunctions, respectively. For 9C, 12C and 13C isotopes, the no-core shell model (NCSM) are studied using the Warburton-Brown interaction. Very good agreements are obtained for the calculated density distributions and form factors in comparison with experimental data.
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Mirnov, R. V., and T. V. Alekseeva. "Paleosols in the Kashira deposits in the south of the East European Craton (Republic of Bashkortostan): characteristics, paleoecological and stratigraphic significance." LITHOSPHERE (Russia) 22, no. 5 (November 4, 2022): 694–704. http://dx.doi.org/10.24930/1681-9004-2022-22-5-694-704.
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Research subject. Paleosols discovered in the Kashira sequence of the Pennsylvanian in the southeastern part of the East European platform. Aim. To study the structure and composition of the paleosols.Materials and methods. Core material from wells was studied by X-ray analysis, scanning electron microscopy and a detailed description of the core and thin sections.Results. Four types of paleosols were identified, three of which are developed on a dolomite substrate. The dolomites are characterized by the following features: microcrystalline structure with a crystal size of 5–10 microns; predominantly euhedral form of crystals, high intercrystalline porosity (up to 38%), inclusions of in situ halite, gypsum and anhydrite, ubiquitous filaments of sepiolite. In paleosols based on a limestone substrate, beta-calcretes with Microcodium were found. The study of fossil roots (rhizoliths) revealed the correlation between their types and substrate composition. Thus, petrified rhizoliths and root casts filled with sedimentary rock and developed clay cutans were found on a dolomite substrate, while calcite tubules around root channels were developed on a limestone substrate. The latter show the presence of abundant Microcodium formations.Conclusions. The revealed morphological and compositional features of the paleosols under study, such as the presence of in situ halite and sulfates (anhydrite and gypsum), sepiolite, and beta calcretes, point to the semiarid climate during the Kashira age on the area under study.
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Belozyorova, Maria, Dmitry Maksimov, Georgiy Razuvaev, Andrey Sukharev, Vitaly Vorobyev, Anastasiia Zhadan, and Daniil Zhadan. "Software framework for the Super Charm-Tau factory detector project." EPJ Web of Conferences 251 (2021): 03017. http://dx.doi.org/10.1051/epjconf/202125103017.
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The project of Super Charm-Tau (SCT) factory — a high-luminosity electron-positron collider for studying charmed hadrons and tau lepton — is proposed by Budker INP. The project implies single collision point equipped with a universal particle detector. The Aurora software framework has been developed for the SCT detector. It is based on trusted and widely used in high energy physics software packages, such as Gaudi, Geant4, and ROOT. At the same time, new ideas and developments are employed, in particular the Aurora project benefits a lot from the turnkey software for future colliders (Key4HEP) initiative. This paper describes the first release of the Aurora framework, summarizes its core technologies, structure and roadmap for the near future.
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Journal, Baghdad Science. "The Nuclear Structure for Exotic Neutron-Rich of 42, 43, 45,47K Nuclei." Baghdad Science Journal 13, no. 1 (March 6, 2016): 146–54. http://dx.doi.org/10.21123/bsj.13.1.146-154.
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In this paper the proton, neutron and matter density distributions and the corresponding root mean square (rms) radii of the ground states and the elastic magnetic electron scattering form factors and the magnetic dipole moments have been calculated for exotic nucleus of potassium isotopes K (A= 42, 43, 45, 47) based on the shell model using effective W0 interaction. The single-particle wave functions of harmonic-oscillator (HO) potential are used with the oscillator parameters b. According to this interaction, the valence nucleons are asummed to move in the d3f7 model space. The elastic magnetic electron scattering of the exotic nuclei 42K (J?T= 2- 2), 43K(J?T=3/2+ 5/2), 45K (J?T= 3/2+ 7/2) and 47K (J?T= 1/2+ 9/2) investigated through Plane Wave Born Approximation (PWBA). The inclusion of core polarization effect through the effective g-factors is adequate to obtain a good agreement between the predicted and the measured magnetic dipole moments.
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Zaychuk, K. S., M. H. Chen, and C. Hiruki. "Portein-gold labelling of ultrathin sections of wheat spot mosaic-affected wheat plants." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 3 (August 12, 1990): 680–81. http://dx.doi.org/10.1017/s0424820100160959.
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Wheat spot mosaic (WSpM), which frequently occurs with wheat streak mosaic virus was first reported in 1956 from Alberta. Singly isolated, WSpM causes chlorotic spots, chlorosis, stunting, and sometimes death of the wheat plants. The vector responsible for transmission is the eriophyid mite, Eriophyes tulipae Kiefer. The examination of leaf ultrastructure by electron microscopy has revealed double membrane bound bodies (DMBB’s) 0.1-0.2 μm in diameter. Dispersed fibrils within these bodies suggested the presence of nucleic acid. However, neither ribosomes characteristic of bacteria, mycoplasma and the psittacosis group of organisms nor an electron dense core characteristic of many viruses was commonly evident.In an attempt to determine if the DMBB’s contain nucleic acids, RNase A, DNase I, and lactoferrin protein were conjugated with 10 nm colloidal gold as previously described. Young root and leaf tissues from WSpM-affected wheat plants were fixed in glutaraldehyde, postfixed in osmium tetroxide,and embedded in Spurr’s resin.
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Rahi, Shaimaa Ali, and Gaith Naima Flaiyh. "Matter Density Distributions, Root-mean Square Radii and Elastic Electron Scattering Form Factors of Some Exotic Nuclei (17B, 11Li, 8He)." Iraqi Journal of Physics (IJP) 19, no. 50 (September 1, 2021): 60–69. http://dx.doi.org/10.30723/ijp.v19i50.675.
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The two-neutron halo-nuclei (17B, 11Li, 8He) was investigated using a two-body nucleon density distribution (2BNDD) with two frequency shell model (TFSM). The structure of valence two-neutron of 17B nucleus in a pure (1d5/2) state and in a pure (1p1/2) state for 11L and 8He nuclei. For our tested nucleus, an efficient (2BNDD's) operator for point nucleon system folded with two-body correlation operator's functions was used to investigate nuclear matter density distributions, root-mean square (rms) radii, and elastic electron scattering form factors. In the nucleon-nucleon forces the correlation took account of the effect for the strong tensor force (TC's). The wave functions of single particle harmonic oscillator are used with two different oscillator size parameters βc and βv, where the former is for the core (inner) orbits and the latter is for the valence (halo) orbits. The measured matter density distributions of these nuclei clearly showed long tail results. To investigate elastic electron scattering form factors the plane wave born approximation (PWBA) with two body nucleon density distribution (2BNDD's) was use.
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Yoshii, Shinji, Sufyan Garoushi, Chiaki Kitamura, Pekka K. Vallittu, and Lippo V. Lassila. "Evaluation of New Hollow Sleeve Composites for Direct Post-Core Construction." Materials 14, no. 23 (December 2, 2021): 7397. http://dx.doi.org/10.3390/ma14237397.
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The preset shape and diameter of a prefabricated FRC post rarely follows the anatomy of the root canal. To solve this problem, a new hollow sleeve composite (HSC) system for post-core construction was developed and characterized. A woven fiber was impregnated with two types of resins: Bis-GMA or PMMA, and rolled into cylinders with outer diameter of 2 mm and two different inner diameters, namely 1.2 or 1.5 mm. The commercial i-TFC system was used as a control. Dual-cure resin composite was injected into these sleeves. Additionally, conventional solid fiber post was used as the inner part of the sleeve. The three-point bending test was used to measure the mechanical properties of the specimens and the fracture surface was examined using an electron microscope (SEM). The HSC (1.5 mm, Bis-GMA) revealed a statistically similar flexural modulus but higher flexural strength (437 MPa) compared to i-TFC (239 MPa; ANOVA, p < 0.05). When a fiber post was added inside, all values had a tendency to increase. After hydrothermal accelerated aging, the majority of specimens showed a significant (p < 0.05) decrease in flexural strength and modulus. SEM fracture analysis confirmed that the delamination occurred at the interface between the outer and inner materials. The HSC system provided flexibility but still high mechanical values compared to the commercial system. Thus, this system might offer an alternative practical option for direct post-core construction.
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Benharrat, H., S. Renaudin, L. Rey, and P. Thalouarn. "Sur la différenciation des trachéides dans les haustoriums d'Osyris alba parasitant Hedera helix." Canadian Journal of Botany 65, no. 8 (August 1, 1987): 1746–55. http://dx.doi.org/10.1139/b87-239.
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The central part of the haustorium of Osyris alba L. contains a cambium which is continuous from the mother root to the vicinity of the "absorbing cells." It centripetally differentiates tracheary elements which make up a vascular core, the xylem bridge, connecting the vessels of the parasite root to those of the host root. In the differentiating cambial cells, a first stage of activity of the Golgi apparatus, which is related to the development of the secondary wall thickenings, is evident. This stage is marked by the presence of numerous vesicles containing an electron dense material and of multivesicular bodies lying near the plasmalemma. The cells also contain numerous spherical granules which, while being mainly proteinaceous, also contain some potassium, calcium, and sulfur. The composition of these granules, the fact that their surrounding membrane is studded with numerous ribosomes and the fact that they often form short chains in a common membranous profile lead us to conclude that they are elaborated in the endoplasmic reticulum. Later in the course of differentiation of those cells, a second stage of activity of the Golgi apparatus can be observed, with the numerous vesicles showing a light content this time. This phase precedes a lysis process during which the cells lose all their cytoplasmic content. Only the granules remain in the differentiated tracheids. [Journal translation]
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Pawłowski, B., P. Bala, T. Tokarski, and J. Krawczyk. "Premature Cracking of Dies for Aluminium Alloy Die-Casting." Archives of Metallurgy and Materials 58, no. 4 (December 1, 2013): 1275–79. http://dx.doi.org/10.2478/amm-2013-0147.
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Abstract Two identical dies for aluminium alloy die-casting failed prematurely because of a number of parallel cracks on the working surface. These cracks were of a mechanical nature related to incorrect microstructural banding orientation of the die core and related to improper heat treatment. The microstructural banding orientation was determined by metallographic examination of the specimens, which were cut from the dies along the three axes of the coordinate system. Scanning electron microscopy (SEM) examination of the fracture surfaces and along the crack path (including energy dispersive spectroscopy (EDS) analysis) indicated that the root cause of the premature cracking of the dies was improper heat treatment (quenching and tempering conditions). Additionally, resistance to fracture of the investigated specimens, as measured by the Charpy V-notch test, was five times lower than that required for the desired hardness.
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Pesic, Milan. "Estimation of doses received by operators in the 1958 RB reactor accident using the MCNP5 computer code simulation." Nuclear Technology and Radiation Protection 27, no. 3 (2012): 199–221. http://dx.doi.org/10.2298/ntrp1203199p.
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A numerical simulation of the radiological consequences of the RB reactor reactivity excursion accident, which occurred on October 15, 1958, and an estimation of the total doses received by the operators were run by the MCNP5 computer code. The simulation was carried out under the same assumptions as those used in the 1960 IAEA-organized experimental simulation of the accident: total fission energy of 80 MJ released in the accident and the frozen positions of the operators. The time interval of exposure to high doses received by the operators has been estimated. Data on the RB1/1958 reactor core relevant to the accident are given. A short summary of the accident scenario has been updated. A 3-D model of the reactor room and the RB reactor tank, with all the details of the core, created. For dose determination, 3-D simplified, homogenised, sexless and faceless phantoms, placed inside the reactor room, have been developed. The code was run for a number of neutron histories which have given a dose rate uncertainty of less than 2%. For the determination of radiation spectra escaping the reactor core and radiation interaction in the tissue of the phantoms, the MCNP5 code was run (in the KCODE option) and ?mode n p e?, with a 55-group neutron spectra, 35-group gamma ray spectra and a 10-group electron spectra. The doses were determined by using the conversion of flux density (obtained by the F4 tally) in the phantoms to doses using factors taken from ICRP-74 and from the deposited energy of neutrons and gamma rays (obtained by the F6 tally) in the phantoms? tissue. A rough estimation of the time moment when the odour of ozone was sensed by the operators is estimated for the first time and given in Appendix A.1. Calculated total absorbed and equivalent doses are compared to the previously reported ones and an attempt to understand and explain the reasons for the obtained differences has been made. A Root Cause Analysis of the accident was done and, for the first time, a Cause and Effect diagram has been created in Cause Mapping methodology and shown in Appendix A.2.
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Benhamou, Nicole, Serge Gagné, Dominique Le Quéré, and Leila Dehbi. "Bacterial-Mediated Induced Resistance in Cucumber: Beneficial Effect of the Endophytic Bacterium Serratia plymuthica on the Protection Against Infection by Pythium ultimum." Phytopathology® 90, no. 1 (January 2000): 45–56. http://dx.doi.org/10.1094/phyto.2000.90.1.45.
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The potential of the endophytic bacterium Serratia plymuthica strain R1GC4 in stimulating defense reactions in cucumber (Cucumis sativus) seedlings inoculated with the soilborne pathogen Pythium ultimum was explored at the cellular level. Bacterial treatment prior to Pythium inoculation resulted in less seedling disease development as compared with that in nontreated control plants, in which typical root symptoms were visible by 3 days after inoculation with the pathogen. Histological investigations of root samples revealed striking differences in the extent of plant defense reactions between bacterized and nonbacterized plants. These observations were further confirmed at the ultrastructural level with the demonstration that restriction of fungal colonization to the outermost root tissues of bacterized seedlings correlated with the deposition of enlarged callose-enriched wall appositions at sites of potential pathogen penetration and the accumulation of an osmiophilic material in the colonized areas. Hyphae of the pathogen, surrounded by this electron-opaque material, exhibited considerable changes including cytoplasm disorganization and, in many cases, loss of the protoplasm. However, labeling with the β-1,4-exoglucanase resulted in a regular labeling of Pythium cell walls, even at a time when these walls were entirely coated by the osmiophilic material. This material was also found to infiltrate into the invading hyphae to form either an internal coating of the cell wall or a network of polymorphic droplets in the area previously occupied by the cytoplasm. Cytochemical investigations revealed that callose, pectin, and cellulose appeared in the wall appositions. In addition, glucosides, lipids, and phenolics were detected in the electron-dense aggregates forming the core of most wall appositions. Finally, galactose residues were among the minor polysaccharidic compounds detected in the wall appositions. Evidence is provided in this study showing that treatment with S. plymuthica sensitizes susceptible cucumber plants to react more rapidly and more efficiently to Pythium attack through the formation of physical and chemical barriers at sites of potential fungal entry.
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ZHANG, Zelong, Cheng WANG, Qiang SUN, and Weidong XIA. "Two-dimensional self-consistent numerical simulation of the whole discharge region in an atmospheric argon arc." Plasma Science and Technology 24, no. 5 (April 13, 2022): 055402. http://dx.doi.org/10.1088/2058-6272/ac55fe.
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Abstract A 2D self-consistent numerical model of the whole argon-arc discharge region that includes electrodes is developed in this work to facilitate analysis of the physical processes occurring in atmospheric arc plasma. The 2D arc column model contains the ionization and thermal non-equilibrium, which is coupled with a 1D electrode sheath model. The influence of plasma-species diffusion near the electrode region is investigated based on Maxwell–Stefan equations and the generalized Ohm’s law. The numerical results of argon free-burning arcs at atmospheric pressure are then investigated. The simulation shows that the plasma is obviously in the state of thermal and ionization equilibrium in the arc core region, while it deviates from thermal and ionization equilibrium in the arc fringe region. The actual electron density decreases rapidly in the near-anode and near-cathode regions due to non-equilibrium ionization, resulting in a large electron number gradient in these regions. The results indicate that electron diffusion has an important role in the near-cathode and near-anode regions. When the anode arc root gradually contracts, it is easy to obtain a positive voltage drop of the anode sheath (I = 50 A), while it remains difficult to acquire a positive anode sheath voltage drop (I = 150 A). The current–voltage characteristics predicted by our model are found to be identical to the experimental values.
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Rocca, GT, JJ Canneto, N. Scotti, R. Daher, A. Feilzer, CM Saratti, and I. Krejci. "Restoration of Severely Damaged Endodontically Treated Premolars: Influence of the Ferrule Effect on Marginal Integrity and Fracture Load of Resin Nano-ceramic CAD-CAM Endocrowns." Operative Dentistry 46, no. 6 (November 1, 2021): 650–60. http://dx.doi.org/10.2341/20-081-l.
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SUMMARY Objectives To explore the ferrule effect on Resin Nano-Ceramic (RNC) premolar endocrown marginal integrity and fracture resistance. Methods Thirty-six root–canal-treated premolars were cut 2 mm above the cemento-enamel junction (CEJ). They were restored with standardized RNC computer-aided design/computer-aided manufacturing (CAD/CAM) restorations (Lava Ultimate, 3M Oral Care, St. Paul, MN, USA) and divided into three groups (n=12): endocrowns with a 3-mm endo-core (Group 1), endocrowns with a 3-mm endo-core and a 2-mm ferrule (Group 2), and conventional post-and-core crowns with a 2-mm ferrule (Group 3). All specimens were submitted to thermo-mechanical cycling loading (TMCL) (1.7 Hz, 49 N, 600 000 cycles, 1500 thermocycles). Margins were analyzed before and after the TMCL. In the second part of the experiment, the surviving specimens were submitted to unidirectional monotonic loading until fracture. Fragments were then analyzed using scanning electron microscopy (SEM) and the fracture mode was established. Results Endocrowns of Groups 1 and 2 performed better than conventional crowns (Group 3) in terms of marginal continuity. Differences in fracture load values within all groups were not statistically significant. Most of the specimens fractured in a non-repairable way. Conclusions The present test failed to provide evidence of any kind of difference between endocrowns with and without a ferrule in terms of load-bearing capacity and marginal integrity after fatigue. Further studies are needed to confirm the role of the ferrule in adhesive restorations of endodontically treated teeth.
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Olawale, Femi, Mario Ariatti, and Moganavelli Singh. "Biogenic Synthesis of Silver-Core Selenium-Shell Nanoparticles Using Ocimum tenuiflorum L.: Response Surface Methodology-Based Optimization and Biological Activity." Nanomaterials 11, no. 10 (September 27, 2021): 2516. http://dx.doi.org/10.3390/nano11102516.
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Bimetallic nanoparticles (BNPs) have shown better biological potential compared to their monometallic counterparts owing to the synergistic effect produced by these alloys. In this study, selenium-capped silver nanoparticles (Ag@Se NPs) were synthesized using an Ocimum tenuiflorum extract. These BNPs were characterized using UV-visible, Fourier transform infrared spectroscopy, nanoparticle tracking analysis, electron microscopy and energy dispersive x-ray analysis. Response surface methodology was used to understand how extract volume and temperature influenced the zeta potential, hydrodynamic size and NP concentration. The phytoconstituents were identified using gas chromatography-mass spectrometry (GC-MS) and molecular docking studies were performed on B-DNA to determine possible genotoxicity. Antioxidant activities, in vitro cytotoxicity (3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay), and genotoxicity (Allium cepa root cells) of these BNPs, were also evaluated. A surface plasmon resonance band around 420 nm confirmed BNP formation with significant quantities of silver and selenium. The Ag@Se NPs displayed good stability, dispersity, antioxidant activity, and compatibility at low concentrations but showed significant cytotoxicity and genotoxicity at high concentrations. Molecular docking analysis showed weak interactions between the plant constituents and B-DNA, suggesting no genotoxicity. These results provide an insight into the conditions required for optimal production of eco-friendly Ag@Se NPs with interesting biological properties.
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Segal, Anthony W. "NADPH oxidases as electrochemical generators to produce ion fluxes and turgor in fungi, plants and humans." Open Biology 6, no. 5 (May 2016): 160028. http://dx.doi.org/10.1098/rsob.160028.
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The NOXs are a family of flavocytochromes whose basic structure has been largely conserved from algae to man. This is a very simple system. NADPH is generally available, in plants it is a direct product of photosynthesis, and oxygen is a largely ubiquitous electron acceptor, and the electron-transporting core of an FAD and two haems is the minimal required to pass electrons across the plasma membrane. These NOXs have been shown to be essential for diverse functions throughout the biological world and, lacking a clear mechanism of action, their effects have generally been attributed to free radical reactions. Investigation into the function of neutrophil leucocytes has demonstrated that electron transport through the prototype NOX2 is accompanied by the generation of a charge across the membrane that provides the driving force propelling protons and other ions across the plasma membrane. The contention is that the primary function of the NOXs is to supply the driving force to transport ions, the nature of which will depend upon the composition and characteristics of the local ion channels, to undertake a host of diverse functions. These include the generation of turgor in fungi and plants for the growth of filaments and invasion by appressoria in the former, and extension of pollen tubes and root hairs, and stomatal closure, in the latter. In neutrophils, they elevate the pH in the phagocytic vacuole coupled to other ion fluxes. In endothelial cells of blood vessels, they could alter luminal volume to regulate blood pressure and tissue perfusion.
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Prajapati, Deepak K., and Mayank Tiwari. "The correlation between friction coefficient and areal topography parameters for AISI 304 steel sliding against AISI 52100 steel." Friction 9, no. 1 (July 29, 2020): 41–60. http://dx.doi.org/10.1007/s40544-019-0323-1.
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Abstract Dry wear experiments provide an insight detail on how severely contacting surfaces change under unlubricated sliding condition. The theory of dry sliding wear is used for understanding mixed-lubrication regime in which asperity interactions play a significant role in controlling of the friction coefficient (f). The purpose of this work is to study the tribological behavior of AISI 304 steel in contact with AISI 52100 steel during wear. Both materials are used in rolling element bearings commanly. Experiments are carried out using a pin-on-disc tribometer under dry friction condition. The areal (three dimensional, 3D) topography parameters are measured using a 3D white light interferometer (WLI) with a 10× objective. After wear tests, wear mechanisms are analyzed utilizing scanning electron microscope (SEM). Factorial design with custom response surface design (C-RSD) is used to study the mutual effect of load and speed on response variables such as f and topography parameters. It is observed that the root mean square roughness (Sq) decreases with an increase in sliding time. Within the range of sliding time, Sq decreases with an increase in the normal load. Within the range of sliding speed and normal load, it is found that Sq, mean summit curvature (Ssc), and root mean square slope (Sdq) are positively correlated with f. Whereas, negative correlation is found between f and correlation length (Sal), mean summit radius (R), and core roughness depth (Sk).
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Mushashe, Amanda Mahammad, Rodrigo Otavio Jatahy Ferreira do Amaral, Carlos Eduardo Edwards Rezende, Flares Baratto Filho, Leonardo Fernandes da Cunha, and Carla Castiglia Gonzaga. "Effect of Sonic Vibrations on Bond Strength of Fiberglass Posts Bonded to Root Dentin." Brazilian Dental Journal 28, no. 1 (December 12, 2016): 30–34. http://dx.doi.org/10.1590/0103-6440201601107.
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Abstract Sonic vibrations may improve the bond strength and durability of fiberglass posts by improving adhesive penetration into dentin as well as the cement flow. The objective of this study was to evaluate the effect of sonic vibrations on the bond strength between fiberglass posts and root dentin using the pull-out test. Bovine roots were endodontically treated and divided randomly into four groups (n=12): Group C - conventional cementation (control); Group SA - sonic vibration (Smart Sonic Device, FGM) of the adhesive system and conventional post accommodation; SP group - conventional adhesive application and sonic vibration of the post during accommodation; and SASP - sonic vibration of the system adhesive and the post during accommodation. The posts were cleaned, treated with a silane and adhesive system (Ambar, FGM), and cemented with a dual-cured resin cement (Allcem Core, FGM). After 24 h, the specimens were subjected to mechanical tests and failure analyses. Representative specimens were analyzed by a scanning electron microscope to observe the cementation line. The results were analyzed using ANOVA and Tukey's test (a=5%). The bond strengths were as follows: SASP (90.9±27.1 N), C (121.4±60.6 N), SA (127.6±31.8 N) and SP (156.4±41.3 N). The use of sonic vibrations during the application of adhesive or post cementation separately did not affect the bond strength but had a negative effect when used for both procedures.
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Borș, Andreea, Melinda Székely, Cristina Molnar-Varlam, and Iulian Vasile Antoniac. "Bioactivity of Retrograde Dental Root Filling Materials." Key Engineering Materials 695 (May 2016): 236–42. http://dx.doi.org/10.4028/www.scientific.net/kem.695.236.
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The placement of appropriate root-end filling materials in contact with periradicular tissues, with improved adaptation and biological properties is critical for the long-term success of the periapical surgery. The purpose of the present study was to evaluate and compare the bio-properties of four different root canal filling materials with respect to storage media. Two mineral trioxide aggregates: MTA-Angelus (Angelus, Londrina, PR, Brazil) and ProRoot MTA (Dentsply Maillefer, Ballaigues, Switzerland) and two glass ionomer cements: one conventional Ketac Molar (3M ESPE AG, Seefeld, Germany) and a resin reinforced core build-up glass ionomer Vitremer (3M ESPE AG, Seefeld, Germany) were evaluated. Eighty healthy single-rooted human extracted teeth without curvature and with closed apices were included in this experiment. The canals were instrumented with K-files up to size #35. Adequate irrigation was performed during preparation and instrumentation using 2.6% NaOCl. Root canals were obturated with vertically condensed gutta-percha and roots end were apically resected 3mm. The samples were randomly divided in four groups (n=20) and each group was assigned to one of the four tested materials. Three-mm depth preparations were made at root ends using cylindrical diamond burs and constant water spray, and were filled with the tested materials. The roots were then wrapped in wet gauze and placed in an incubator at 37°C for 48 hours to allow complete set of the root-end filling materials. Each group was divided in two subgroups (n=10) and stored in polypropylene sealed containers for 60 days at 37°C. Specimens of the first subgroup were immersed in 5ml of a physiological-like buffered Ca- and Mg-free solution (PBS, pH=7.4) and those of the second subgroup were in 5ml of deionized water (DW, pH 6.8) After 10 minutes of immersion and at the established endpoint times, the specimens were analyzed by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). Statistical analysis was performed by t-test and one-way ANOVA (p<0.05). The morphology of cement–dentin interface in fresh restorations soaked 10 min in PBS showed the margins of all cements free from porosities or gaps. EDX elemental analyzes on MTA and ProRoot MTA revealed calcium, silica and phosphorous peaks, while on Ketac Molar and Vitremer, aluminum, silica, zinc and fluoride peaks were detected. After 60 days of immersion in PBS calcium-phosphate deposits completely covered the surface, the margin and partially also the peripheral dentin surface of MTA and Pro Root MTA. Glass ionomer cements showed the presence of thick irregular deposits (p<0.05). In deionized water, EDX analyses revealed no deposits forming after 60 days. SEM analysis showed the margins of MTA and ProRoot MTA with significant discontinuities compared with glass ionomer cements (p<0.05). Mineral trioxide aggregate cements are significantly more bioactive compared to conventional or reinforced glass ionomers upon aging in PBS. Glass ionomer cements provide more optimal adaptation to dentinal cavity walls of all cements than MTA cements when used as retrograde fillings.
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Maden, Murat, Güliz Görgül, A. Cemal Tinaz, Bağdagül H. Kivanç, and Özgür like Atasoy Ulusoy. "Effects of Nd: YAG Laser Irradiation on the Adaptation of Composite Resins to Root Dentin." Journal of Contemporary Dental Practice 6, no. 4 (2005): 116–23. http://dx.doi.org/10.5005/jcdp-6-4-116.
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Abstract One of the most important goals of the restoration of endodontically treated teeth with a composite resin post system is to achieve good adaptation of the composite material to dentin walls to prevent microleakage apically and coronally. In post core systems, to avoid microleakage between the dentin wall and resin material, laser irradiation may seem to be an alternative therapy for increasing adaptation quality. The aim of this study was to investigate the adaptation of a packable composite resin to lased root canal dentin when it was used as post material. Forty-five freshly extracted human teeth were selected and post spaces were prepared. The teeth were divided into three groups. In group 1 the dentin of the post spaces were etched with 35% phosphoric acid, in group 2 the dentin surfaces were irradiated with an Nd: YAG laser, and in group 3 the dentin surfaces were initially treated with the laser and then etched. The teeth of all groups were obturated with a bonding agent and composite. The groups were divided into two subgroups: a group for the scanning electron microscope (SEM) study and a group for the microleakage study. The lased group showed poor adaptation and more microleakage was detected (p<0.05; variance analysis). The laser beam and acid-etching showed no advantage compared to the acid-etching alone (p>0.05). The Nd: YAG laser irradiation adversely affects adhesion to dentin for using composite resin as a post material and does not constitute an alternative to acid-etching. Citation Görgül G, Kivanç BH, Maden M, Ulsoy ÖLA, Tinaz AC. Effects of Nd: YAG Laser Irradiation on the Adaptation of Composite Resins to Root Dentin. J Contemp Dent Pract 2005 November;(6)4:116-123.
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Decurcio, Daniel De Almeida, Julio Almeida Silvaa, Mateus Gehrke Barbosa, Lucas Silva Chaves, Marco Antônio Zaiden Loureiro, and Carlos Estrela. "Characterization of the nucleus, cutting edge and failure detection in NiTi instruments for endodontic retreatment." Revista Odonto Ciência 32, no. 4 (July 25, 2018): 193. http://dx.doi.org/10.15448/1980-6523.2017.4.30157.
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OBJECTIVE: To characterize the nucleus, cutting edge and to detect defects in surfaces of nickeltitanium (NiTi) instruments for endodontic retreatment.METHODS: The selected endodontic instruments (D-RaCe, ProTaper retreatment and Mtwo retreatment) were evaluated prior to their use in 30- and 50-fold magnification in scanning electron microscopy (SEM), for linear measurements of lateral cut edge areas and of the nucleus and the ratio between these measures. After use in simulated canals, faults in the active surface were analyzed by SEM with 30 and 50 times magnification, and 200 times magnification when faults were found. The images were examined by three evaluators, whose measurements were previously calibrated. The defects analyzed were crack, blunt and barb, and data were tabulated for analysis.RESULTS: The instruments studied differed in results. The D-RaCe system instruments had the highest nucleus:edge ratio, while ProTaper retreatment instruments yielded the lowest ratio. All instruments presented some defect, with the instruments Mtwo retreatment presenting two instruments with defects.CONCLUSION: All analyzed instruments presented some type of failure after using them for removal of the filling material of simulated root canals. The D-RaCe system presented the highest edge measurements and the smallest nucleus measurements, contrary to the ProTaper retreatment system, which presented the smallest edge measurements and the largest core measurements.
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Kadivar, Ali, and Kaveh Niayesh. "Effects of Fast Elongation on Switching Arcs Characteristics in Fast Air Switches." Energies 13, no. 18 (September 16, 2020): 4846. http://dx.doi.org/10.3390/en13184846.
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This paper is devoted to investigating the effects of high-speed elongation of arcs inside ultra-fast switches (ucontact≈ 5–80 m/s), through a 2-D time-dependent model, in Cartesian coordinates. Two air arcs in series, one between a stationary anode and a moving cathode and the other between a stationary cathode and a moving anode in the arc chamber, are considered. A variable speed experimental setup through a Thomson drive actuator is designed to support this study. A computational fluid dynamics (CFD) equations system is solved for fluid velocity, pressure, temperature, and electric potential, as well as the magnetic vector potential. Electron emission mechanisms on the contact surface and induced current density due to magnetic field changes are also considered to describe the arc root formation, arc bending, lengthening, and calculating the arc current density, as well as the contact temperatures, in a better way. Data processing techniques are utilized to derive instantaneous core shape and profiles of the arc to investigate thermo-electrical characteristics during the elongation progress. The results are compared with another experimentally verified magnetohydrodynamics model of a fixed-length, free-burning arc in the air. The simulation and experimental results confirm each other.
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He, You Liang, Mehdi Mehdi, Erik J. Hilinski, and Afsaneh Edrisy. "Magnetic Barkhausen Noise Characterization of the Recrystallization of a Non-Oriented Electrical Steel after Cold Rolling at Different Angles to the Hot Rolling Direction." Materials Science Forum 941 (December 2018): 274–79. http://dx.doi.org/10.4028/www.scientific.net/msf.941.274.
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Non-oriented electrical steel sheets are the most commonly used material for the manufacturing of magnetic cores for electric motors and generators. The microstructure and texture of the steel after final annealing have a significant effect on the magnetic properties of the lamination core. To investigate the effect of cold rolling and annealing on the magnetic properties of the steel sheets, a 0.9 wt% Si non-oriented electrical steel was cold rolled at different angles to the hot rolling direction (HRD) and annealed at various temperatures (600°C to 750°C) to produce dissimilar microstructures. The progress of recrystallization was characterized by electron backscatter diffraction (EBSD), and the magnetic response of the steel at various stages of recrystallization was evaluated by magnetic Barkhausen noise (MBN). A number of MBN parameters, e.g. the root mean square, the smoothed envelope, the peak, the full width at half maximum (FWHM) of the envelope, the time integral of the MBN signals and the MBN energy, were analyzed with respect to the fraction of recrystallization during annealing. The results show that cold rolling at different angles to the hot rolling direction induces various deformation microstructures and stored energies, which, in turn, lead to considerably different recrystallization behaviours during annealing. The difference in recrystallization of these materials is also reflected in the MBN parameters.
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Yılmaz, Berivan Dündar, and Ayça Deniz İzgi. "Effect of different surface treatments on bond strength between zirconia posts and root surfaces." International Dental Research 10, no. 2 (August 31, 2020): 49–54. http://dx.doi.org/10.5577/intdentres.2020.vol10.no2.4.
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Aim: In recent years, especially with the increase in aesthetic demands, there has been a requirement to use the best aesthetic materials for dental restorations. These restorations are especially needed in those teeth that have crown loss due to a tooth fracture or extreme anterior tooth decay, post-core treatment has been applied as getting support by tooth roots. the aesthetic disadvantages and making use of the strength resistance of various metals. In this case, zirconium, which is a white‑coloured metal, is preferred. In this study, zirconia posts with different surface treatments were cemented to the root canal and bond strength was then evaluated.
Materials and Methods: Forty mandibular second premolar teeth were used in this study. Crowns of all teeth were removed to 14 mm from the enamel-cement margin by separation under irrigation. Root canals were cleaned, shaped and filled. Teeth were kept in distilled water while zirconia posts were prepared. Zirconia posts were divided into four groups according to the surface treatment methods as follows: a control group, a CoJet applied group, a sandblasting+laser group and an Er:YAG laser group. The Er:YAG laser was administered at 450 mJ at 10 Hz for 60 seconds with a 100-μs pulse duration. Surface-treated posts were bonded to the root canal with Panavia F cement. Cores were made with the standardized strip crowns. 5000 cycles, 5-55 °C thermal cycle applied with transition time at 5 seconds. For push-out tests, roots were embedded in translucent acrylic resin and coronal, middle third and apical sections were cut into 1.5-mm slices. The maximum load at failure was recorded for each specimen in newtons and then converted into megapascals (MPa). Each specimen was inspected with a scanning electron microscope (SEM) at a magnification of 100 X. Data were analysed using Games‑Howell tests with a significance level of 0.05.
Results: The coronal section from Group 3 had the highest mean push-out bond strength (18.01 MPa), while the apical section from Group 1 had the lowest (4.49 MPa). Surface treatments had no significant effect on the mean push-out bond strengths of zirconia posts (p > 0.05). However, dividing the root canal into three sections had a significant effect on bond strength (p < 0.05). When the results were evaluated for all groups, the push-out bond strength was highest in the coronal section, then in the middle third and the lowest in the apical section.
How to cite this article:
Dündar Yılmaz B, İzgi AD. Effect of different surface treatments on bond strength between zirconia posts and root surfaces. Int Dent Res 2020;10(2):49-54. https://doi.org/10.5577/intdentres.2020.vol10.no2.4
Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.
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Goździewska-Harłajczuk, Karolina, Pavla Hamouzová, Joanna Klećkowska-Nawrot, and Petr Čížek. "The tongue of the red panda (Ailurus fulgens fulgens Cuvier, 1825)—a stereoscopy, light microscopy and ultrastructural analysis." PeerJ 9 (November 25, 2021): e12559. http://dx.doi.org/10.7717/peerj.12559.
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In the light of recent molecular studies, there are two phylogenetic species of the red panda (Ailurus fulgens): Ailurus fulgens fulgens and Ailurus fulgens styani. The red panda belongs to the endangered species living in the wild only in Asia and is included in the CITES list. Although the biology and diet of this species has been extensively described, the histological structure of the tongue and lingual glands has not yet been characterized in detail in relation to the lifestyle of this mammal under specific conditions and as a basis for comparative anatomical studies of the biodiversity of endemic species. Study samples were collected from two adult males of Ailurus fulgens f. held in Wrocław Zoological Garden. Both tongues were examined macroscopically; moreover, samples with lingual papillae for light microscopy and scanning electron microscopy (SEM) were collected from the apex, body and root of the tongue. Both tongues of the Ailurus fulgens f. males were approximately 9 cm long. The dorsal lingual surface was covered with mechanical and gustatory lingual papillae. Filiform papillae were observed on the apex and the body of the tongue, while small conical papillae were observed on the root of the tongue. An elongated, 1–1.5 cm long cylinder-shaped lyssa was observed in the ventral part of the apex. Moreover, most numerous and largest round in shape fungiform papillae were observed on the apex and on the border of the body and root of the tongue, located directly rostrally to 12–13 round and oval in shape vallate papillae. The SEM study showed that filiform papillae on the apex had several long secondary processes, while filiform papillae on the body of the tongue were taller and their secondary papillae were shorter than the equivalent structures on the apex of the tongue. The SEM study showed numerous taste pores on the surface of the fungiform papilla, while irregular surface of the vallate papillae, however some of them had smoother surface. Mixed glands (comprised of mucous acini and serous acini) were present within the vallum (within the connective tissue core) of the vallate papilla. Beneath the papillae more serous glands were observed, while the posterior lingual glands in the caudal part of the root of the tongue were mucoserous (mucous units were prevalent). A characteristic feature of the tongue of Ailurus fulgens f. was the presence of lyssa, which is comparable to other representatives of Carnivora, but the number of vallate papillae was individually variable. The lack of strongly developed mechanical conical papillae probably may be related to the type of plant food that is particularly dominant in red panda. Further differences between Ailurus fulgens f. and Ailurus fulgens s. cannot be excluded. The results of these studies may be useful especially for veterinarians specializing in working with exotic animals and people dealing with wildlife conservation.
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Khatibi, Aram dokht khatibi, Zarrin Eshaghi, Hamid Mosaddeghi, and Davoud Balarak. "Molecular Dynamics Simulation, Characterization and In Vitro Drug Release of Isoniazid Loaded Poly-ε-caprolactone Magnetite Nanocomposite." Pharmaceutical Sciences 26, no. 4 (May 25, 2020): 406–13. http://dx.doi.org/10.34172/ps.2020.36.
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Background: This study reports on the development of a controlled-release isoniazid (INH) drug delivery system using poly-є-caprolactone (PCL) functionalized magnetite-nanoparticles (MNPs), as a theoretical potential tool for tuberculosis (TB) chemotherapy. Method: The magnetite Fe3O4 core was fabricated by the co-precipitation method and coated with PCL by emulsion polymerization. INH was loaded onto the PCL-MNP surface to shape an INH-PCL-MNP nanocomposite. Deposing the INH on the nanocomposite surface was demonstrated through the molecular dynamics simulations. To investigate the stability of the polymer, the root-mean-square deviation (RMSD) and the radius of gyration (Rg) were calculated. The composite was characterized by Scanning electron microscopy (SEM) and X-Ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Mycobacterium tuberculosis was used to assess the antimicrobial activity of the nanoparticles. The drug loading efficiency, drug content, and in-vitro release behavior of the INH-PCL-MNPs were evaluated by UV–Vis spectrophotometry. Results: RMSD of PCL show that the structure of polymer after 40 ns is stable. INH molecules interested to spend more time close to the polymer. Rg of PCL indicated that PCL folded and radius of gyration changed near 1nm. The drug loading efficiency and drug content of the NPs were 720±46 mg/g and 69.3±3.8 (%), respectively. The compound showed a strong level of activity in-vitro. The amount of drug release at all times was above the minimum inhibitory concentration (MIC) (6 μg/ml). Conclusion: INH-PCL-MNP nanocomposite have been effectively used as a potential tool to treat TB infections and a magnetic drug carrier system.
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Litvin, V. A., A. V. Zaporozhets, and I. O. Ozivska. "Silver Nanocomposite Based on Synthetic Humic Substances as Highly Efficient Plant Growth Stimulants." CHERKASY UNIVERSITY BULLETIN: BIOLOGICAL SCIENCES SERIES 1 (2022): 44–55. http://dx.doi.org/10.31651/2076-5835-2018-1-2022-1-44-55.
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Introduction. Nanotechnology have positive impact in improving many sectors of economy including agriculture. Silver nanoparticles (AgNPs) have been implicated nowadays to enhance seed germination, plant growth, improvement of photosynthetic quantum efficiency and as antimicrobial agents to manage plant diseases.Despite the known growth-stimulating activity of preparations of humic substances and silver nanoparticles, there is currently no information on the effect on growth processes of composites containing silver nanoparticles encapsulated in macromolecules from synthetic humic substances. It is expected that such combined nanopreparations have enhanced and complementary properties of a metal core and a shell of humic synthetic substances.Purpose. The aim of this study was to investigate the growth-stimulating activity of silver nanocomposites based on synthetic humic substances derived from quercetin, and to determine the range of active concentrations in the process of germination of wheat seeds.Methods. The received silver nanoparticles are characterized by UV–visible spectroscopy, X-ray diffraction (XRD), FT-IR spectroscopy and transmission electron microscopy (TEM). To study the growth-stimulating activity of synthetic humic substances and silver nanocomposites, a series of solutions was prepared on their basis by dilution with a logarithmic decrease in concentration from 1·10–1 to 4·10-16%.Result. Nanobiocomposites containing silver nanoparticles and synthetic humic substances were synthesized in the reaction of reduction of silver ions with synthetic humic substances obtained in laboratory conditions from quercetin.Preference of synthetic humic substances over natural humic substances is determined by a standardization problem resolution due to the strict control of conditions of the HS formation that expands the areas of application of the silver nanoparticles made on their basis. The high crystallinity of nanobiocomposites with fcc phase is evident from XRD patterns. The TEM results show that the silver nanoparticles are spherical in shape with average size about 9.6 nm. The FTIR spectroscopic study confirmed that the synthetic humic substances have ability to perform dual functions of reduction and stabilization of silver nanoparticles.The growth-promoting activity of synthetic humic substances and silver nanocomposites based on them was studied on the example of germination of wheat seeds of the variety "Zolotokosa" according to standard procedures. It is established that aqueous solutions of synthetic humic substances and silver 54 Серія «Біологічні науки», 202 2nanocomposites based on them in a wide range of concentrations have a complex effect on the growth and development of wheat seeds. It is shown that seed germination increases (by 2–40%) and the length of the main root (by 9–100%) of wheat germ increases. It should be noted that synthetic humic substances and silver nanocomposites based on them to a greater extent stimulate root growth, which is important for agriculture in arid areas. The ranges of effective concentrations of solutions of the studied drugs show the maximum total stimulating activity (by the number of germinated seeds and the length of the main root compared to the control) during germination of wheat seeds for synthetic humic substances and for silver nanocomposite - 10-10-10-4%. Stimulation of root growth by silver nanocomposites based on synthetic humic substances in most concentrations exceeds the effect of the original humic substances.Originality. The established activity of synthetic humic substances and silver nanocomposites based on them is a prerequisite for the further development of highly effective growth-stimulating preparations of a new generation.Conclusion. It has been established that silver nanocomposites based on synthetic humic substances exhibit highly effective growth-stimulating activity. The ranges of active concentrations of the studied preparations demonstrate the optimal stimulating activity for synthetic humic substances and silver nanocomposite based on them by the number of germinated seeds 1·10–10–1·10–4 %, by the length of the main roots compared to the control - 1· 10-12-1· 10-4%. The established activity of synthetic humic substances and silver nanocomposites based on them is a prerequisite for the further development of highly effective growth-stimulating preparations of a new generation.Key words: synthetic humic substances; silver nanocomposites; growth-promoting activity; wheat
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Apostolska, Sonja, Elizabeta Gjorgievska, Vasilka Rendzova, Marina Eftimoska, Rade Zivkovic, and Ivica Stancic. "Adaptability of different canal sealers to the root canal dentin - scanning electron microscopy analysis." Medical review 70, no. 5-6 (2017): 141–45. http://dx.doi.org/10.2298/mpns1706141a.
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Introduction. The aim of this in vitro study was to test and analyze the sealing ability of three endodontic materials used for permanent obturation, in between the dentin walls and the gutta-percha points, using a scanning electron microscope. Material and Methods. Forty-five recently extracted single-root teeth, treated by a step-back technique, were divided into three groups (15 teeth in each); the canals were filled with three different permanent obturation materi?als: N2 - zinc oxide root canal cement, Gutta Flow (Coltene), and Endomethasone N (Septodont). Their sealing ability and adhesive properties were analyzed using field emission gun scanning electron microscope, at the time when they were applied between the dentin walls of the canal and the gutta-percha. Results. The results of the scanning electron microscope analysis have shown that all the three sealers have good adhesion properties when used over the root canal walls in the apical third. Good adaptation of the filling used for the root canal walls in the middle and the cervical third was found only in teeth obturated using Gutta Flow, while samples obturated by N2 - zinc oxide root canal cement and Endomethasone showed the weak?est adhesion, and greatest number of cracks between the sealer and the canal wall. Conclusion. When using a single-cone obturation technique, compared to other obturation materials, Gutta Flow shows considerably better adaptation to the root canal wall and the gutta-percha points in the apical, middle, and the cervical third of the root.
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Sytova, Svetlana. "NUMERICAL ANALYSIS OF LASING DYNAMICS IN VOLUME FREE ELECTRON LASER." Mathematical Modelling and Analysis 13, no. 2 (June 30, 2008): 263–73. http://dx.doi.org/10.3846/1392-6292.2008.13.263-274.
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Nonlinear phenomena originating in volume free electron laser (VFEL) are investigated by methods of mathematical modelling using computer code VOLC. It was demonstrated the possibility of excitation of quasiperiodic oscillations not far from threshold values of electron beam current density and VFEL resonator length. It was investigated sensibility of numerical solution to initial conditions for different VFEL regimes of operation. Parametric maps with respect to electron beam current and detuning from synchronism condition present complicated root to chaos with windows of periodicity in VFEL. Investigation of chaotic lasing dynamics in VFEL is important in the light of experimental development of VFEL in Research Institute for Nuclear Problems.
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Mustaffa, Musliana, Hajar Ar Rahmah Nasri, Insyirah Kamarulzaman, and Mohamad Shafiq Mohd Ibrahim. "GuttaFlow Bioseal as Monocone Obturation Technique in Curved Root Canals: A Scanning Electron Microscopy Study." Science Letters 15, no. 2 (June 15, 2021): 42–59. http://dx.doi.org/10.24191/sl.v15i2.13824.
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The obturation quality of GuttaFlow Bioseal in curved root canals is not commonly investigated although there has been a current approach toward utilizing this material in extracted molars in recent years. This study assessed the obturated surface area, extrusion of root filling material beyond the apical foramen and duration of obturation procedure in curved root canals using monocone obturation technique. Access cavity was prepared in 20 human mandibular molars. Root canals with curvature of more than 10 as determined according to Schneider’s method were included. Samples were prepared using Hyflex CM rotary files and divided into two groups (n=10): Group 1 [gutta-percha cone and GuttaFlow Bioseal] and Group 2 [gutta-percha cone and RoekoSeal Automix root canal sealer]. The duration of obturation procedure was recorded and obturation radiographs were taken. Samples were bisected and the mesial roots were sectioned horizontally to obtain 3 root segments; apical, middle and coronal. All resected roots were mounted on brass stubs, sputter-coated with thin platinum coating and observed under scanning electron microscope (SEM) at 70x magnification. The SEM images were transferred to the SketchAndCalc Area Calculator software. No statistically significant differences in the obturated surface area and extrusion of root filling material were observed between Group 1 and 2, irrespective of the status of root canal curvature. Duration for obturation in severe root canal curvatures between Group 1 and 2 were statistically significant. Obturated surface area and extrusion of root filling material were not affected by the root canal curvature, however duration for obturation using GuttaFlow Bioseal in severe root canal curvatures was slightly longer.
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Turner, A., B. Wells, and K. Roberts. "Plasmodesmata of maize root tips: structure and composition." Journal of Cell Science 107, no. 12 (December 1, 1994): 3351–61. http://dx.doi.org/10.1242/jcs.107.12.3351.
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A procedure is described for obtaining clean maize cell wall preparations that contain embedded plasmodesmata. Negative staining and rotary shadowing have been used with transmission electron microscopy to visualise the plasmodesmata in these isolated walls, and to assess the effects of simple biochemical treatments on plasmodesmal components. Light protease treatment removes material from the exposed ends of plasmodesmata but does not extract the plasmodesmal core, which lies within the cell wall. However, heavy proteolysis occasionally removes the complete plasmodesma, including its enclosing collar structure, from the wall. Extraction with urea has a similar effect. The collar itself appears not to be proteinaceous in composition, although protein may bind it into the wall. Callose is localised in the wall around plasmodesmata, but does not appear to be a constituent of the collar. The membrane components of the plasmodesma (plasma membrane and desmotubule) can be extracted with membrane-solubilising detergents. This treatment releases from the wall a small number of proteins that are regarded as being potentially of plasmodesmal origin. These results show that plasmodesmata from maize can be dissected biochemically and suggest a strategy for the characterisation of individual molecular components.
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Kim, Yemi, Donghee Lee, Da-Vin Kim, and Sin-Young Kim. "Analysis of Cause of Endodontic Failure of C-Shaped Root Canals." Scanning 2018 (November 25, 2018): 1–7. http://dx.doi.org/10.1155/2018/2516832.
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The purpose of this study was to analyze various characteristics and classification of C-shaped root canals and evaluate the causes of endodontic failure of C-shaped root canals by examining the resected root surface with an endodontic microscope and a scanning electron microscope (SEM). Forty-two teeth with C-shaped root canals were included in this study and had undergone intentional replantation surgery. Before surgery, periapical radiography and cone-beam computed tomography were taken. The root canal configuration was analyzed and classified according to Melton’s classification at coronal and apical level. After injection of 1 : 100,000 epinephrine with 2% lidocaine, the tooth was carefully extracted. After the root-end resection, the resected root surface was examined using an operating microscope and SEM. Mandibular second molars were most frequently involved teeth (90.4%). The most frequently observed root canal configurations were C1 at the coronal level (45.2%) and C3 at the apical 3 mm level (45.2%). The most common cause of failure for a C-shaped root canal treatment was a leaky canal (45.2%), followed by an isthmus (23.8%), missing canal, overfilling, and iatrogenic problems. In conclusion, C-shaped root canals were most frequently found in mandibular second molars. The most common cause of failure was a leaky canal and isthmus.
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Zanza, Alessio, Rodolfo Reda, Elisa Vannettelli, Orlando Donfrancesco, Michela Relucenti, Shilpa Bhandi, Shankargouda Patil, Deepak Mehta, Jogikalmat Krithikadatta, and Luca Testarelli. "The Influence of Thermomechanical Compaction on the Marginal Adaptation of 4 Different Hydraulic Sealers: A Comparative Ex Vivo Study." Journal of Composites Science 7, no. 1 (January 4, 2023): 10. http://dx.doi.org/10.3390/jcs7010010.
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Since there are no data in the literature regarding the comparison of the marginal adaptation of hydraulic sealers when used with a single-cone technique or through thermomechanical compaction, this study aimed to evaluate the behavior of four different endodontic sealers used with the two above-mentioned obturation techniques by evaluating the marginal gap existing between the obturation materials and the dentinal walls through scanning electron microscopy. Given this objective, a total of 104 single-rooted, straight canal teeth were selected and divided into four subgroups according to the selected endodontic sealer ((AH) Plus Bioceramic Sealer (AHP), EndoSequence BC Sealer HiFlow (ES), C-Root SP (CR), and GuttaFlow Bioseal (GF)). Each tooth was decoronated and instrumented with the HyFlex EDM/CM systematics up to 30.04. After irrigation procedures, the teeth of each subgroup were divided into two groups and obturated according to two different obturation techniques: the single-cone technique (SC) and the thermomechanical compaction technique (TC). After the required sealer setting time, each tooth was sectioned in three parts at 3, 6, and 9 mm from the apex, and each section was observed with a scanning electron microscope. The marginal gap of each sample was measured using G* Power Software v3.1, and the statistical analysis was performed using the Kruskal–Wallis test, followed by a post hoc Dunn’s test. Results showed that there were not any statistically significant differences in terms of the marginal gap between the two different above-mentioned obturation techniques for each sealer, except for the middle third of root canals, where a statistically significant difference was found for AHP, ES, and GF sealers. In conclusion, the thermomechanical compaction of hydraulic sealers and gutta-percha guarantees better sealing than the single-cone technique when the root canal shape is not rounded.
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Paszkowski, Robert, Jacek Krawczyk, Włodzimierz Bogdanowicz, Dariusz Szeliga, and Jan Sieniawski. "Heterogeneity of the Dendrite Array Created in the Root of Cored SX Turbine Blades during Initial Stage of Crystallization." Materials 14, no. 1 (December 26, 2020): 80. http://dx.doi.org/10.3390/ma14010080.
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The roots of cored single-crystalline turbine blades made of a nickel-based CMSX-4 superalloy were studied. The casts were solidified by the vertical Bridgman method in an industrial ALD furnace using the spiral selector and selector continuer situated asymmetrically in the blade root transverse section. Scanning electron microscopy, the Laue diffraction and X-ray diffraction topography were used to visualize the dendrite array and the local crystal misorientation of the roots. It has been stated that heterogeneity of the dendrite array and creation of low-angle boundaries (LABs) are mostly related to the lateral dendrite branching and rapid growth of the secondary and tertiary dendrites near the surface of the continuer–root connection. These processes have an unsteady character. Additionally, the influence of the mould walls on the dendrite array heterogeneity was studied. The processes of the lateral growth of the secondary dendrites and competitive longitudinal growth of the tertiary dendrites are discussed and a method of reducing the heterogeneity of the root dendrite array is proposed.
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Liang, Jiahao, Ziyang Hu, Dantong Cao, Ya Cao, Xin Xie, Antian Gao, Zhiyong Wang, and Zitong Lin. "Establishment of Narrow Root Fracture Models Using Modified Temperature Cycling Method and Diagnosis Using Different Cone-Beam CT Units." Scanning 2022 (July 14, 2022): 1–7. http://dx.doi.org/10.1155/2022/3636795.
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Aim. Using a modified thermal cycling method to establish narrow root fracture models and evaluate the diagnosis efficiency of them using four different cone-beam CT (CBCT) units. Methodology. Fifty-six intact teeth were selected, and the crowns of the teeth were embedded using general purpose acrylic resin. 50 root fracture models were established by soaking these teeth in liquid nitrogen and hot water cyclically; 6 teeth were used as the negative control. All the 56 teeth were scanned with the smallest voxel size of four different CBCT units (NewTom VGi, Planmeca Promax 3D Max, Kavo 3D eXam, and Soredex Scanora3D). 10 teeth were randomly selected, and the roots were sliced using slow-speed saw to obtain horizontal root sections. Scanning electron microscope (SEM) was used to measure the width of the fracture lines (FLs). The CBCT images were evaluated for the presence or absence of fracture lines. Accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated for the diagnosis of FLs using the four CBCT units. Results. Fifty narrow root fracture models were successfully established, and 25 root sections with 45 FLs were acquired. The width of FLs was from 3.43 μm to 143 μm; 32.2% of the points had width under 25 μm, while only 9.6% of them had width over 75 μm. The accuracy was 0.41, 0.54, 0.41, and 0.30 for NewTom VGi, Planmeca Promax 3D Max, Kavo 3D eXam, and Soredex Scanora3D, respectively. Conclusions. The modified temperature cycling method is a simple and effective method to establish narrow root fracture models, and the diagnosis efficiency for these narrow fracture lines was quite poor using all the four different CBCT units.
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Itoh, Yasunobu, Taku Sugawara, Masayoshi Kowada, and Alan Tessler. "Time Course of Dorsal Root Axon Regeneration into Transplants of Fetal Spinal Cord: An Electron Microscopic Study." Experimental Neurology 123, no. 1 (September 1993): 133–46. http://dx.doi.org/10.1006/exnr.1993.1146.
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Spinelli, Andrea, Fausto Zamparini, Alessio Buonavoglia, Paolo Pisi, Maria Giovanna Gandolfi, and Carlo Prati. "Reciprocating System for Secondary Root Canal Treatment of Oval Canals: CBCT, X-rays for Remnant Detection and Their Identification with ESEM and EDX." Applied Sciences 12, no. 22 (November 17, 2022): 11671. http://dx.doi.org/10.3390/app122211671.
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Aim of the study: to evaluate root filling remnants after secondary root canal treatments (SRCTs) of oval-shaped canals with X-rays and cone beam computed tomography (CBCT). The SRCTs were performed using reciprocating NiTi instruments. Methods: Single-rooted teeth (N = 64) were randomly treated with Reciproc Blue (RB) and filled with AH Plus/single cone (SC group) or AH Plus/Guttafusion (GF group). After seven days of storage in HBSS (Hanks balanced salt solution), Gates Glidden burs #2/3 and RB #25 and #40 were used for the SRCTs. The time to complete the procedure was measured. X-rays and CBCT were used to calculate, respectively, the area and the volume occupied by the remnants in the coronal, middle, and apical thirds of each canal. Environmental scanning electron microscopy (ESEM) and energy dispersive X-ray spectroscopy (EDX) were used for qualitative evaluation and morphology composition of the remnants in sectioned roots. A statistical analysis was performed using Sigma Plot (version 13, IBM, Armonk, NY, USA). The study was designed according to PRILE guidelines. Results: After the SRCTs, the middle thirds of the root canals showed the presence of remnants in both groups, as demonstrated by X-rays and CBCT. The GF group showed a statistically significant higher volume of remnants than the SC Group only in the middle third. The ESEM supported by the EDX revealed the remnant composition by the detection of trace elements of sealer and gutta-percha in all root canals. Conclusion: The study demonstrated that the middle third of root canals is a critical region where remnants were packed and spread in the buccal-lingual sides of canals. ESEM-EDX detected a fine layer of filling remnants in all root thirds, suggesting a larger canal contamination than the X-rays and CBCT examinations revealed.
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Storey, Richard, R. Gareth Wyn Jones, Daniel P. Schachtman, and Michael T. Treeby. "Calcium-accumulating cells in the meristematic region of grapevine root apices." Functional Plant Biology 30, no. 6 (2003): 719. http://dx.doi.org/10.1071/fp02212.
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Apical roots of grapevines were examined by cryo-SEM (scanning electron microscopy) and the intracellular distribution of Ca was demonstrated by X-ray microanalysis in different regions of the primary root. We show that large amounts of Ca are accumulated as raphide crystals in the vacuoles of specialised cortical cells (idioblast cells) of the root apex. These crystal idioblast cells appeared to form a discontinuous cone of cells in the outer region of the root meristem. The raphide crystals within these cells were less apparent in older regions of the root, 10–12 mm basipetal to the root tip. We suggest that the raphide crystals could initially act as another Ca sink involved in the regulation of Ca levels in root apices. In older regions of the root these cells are spaced at intervals around the periphery of the cortex and the subsequent disappearance of the raphides may be indicative of remobilisation, perhaps in the zone of elongation where cell wall synthesis occurs and Ca demand is high. Calcium-accumulating cells were also observed in the older regions of the root, forming endodermal protrusions extending into the cortex. These cells may play a part in regulating Ca delivery to the xylem stream by sequestration of Ca from the radial flow of water at the endodermis. The observed distribution of Ca in root apices was different from the other major cations (e.g. K) and anions (e.g. Cl) because high concentrations were localised to specific cells. We interpret the results in the context of a model of the dynamics of grapevine root growth and cell differentiation, and the temporal balance of solute supply from the protophloem and the external medium.
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Abdelazeem, Mohamed, Rahmi N. Çelik, and Ahmed El-Rabbany. "MGR-DCB: A Precise Model for Multi-Constellation GNSS Receiver Differential Code Bias." Journal of Navigation 69, no. 4 (December 14, 2015): 698–708. http://dx.doi.org/10.1017/s0373463315000922.
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In this study, we develop a Multi-constellation Global Navigation Satellite System (GNSS) Receiver Differential Code Bias (MGR-DCB) model. The model estimates the receiver DCBs for the Global Positioning System (GPS), BeiDou and Galileo signals from the ionosphere-corrected geometry-free linear combinations of the code observations. In order to account for the ionospheric delay, a Regional Ionospheric Model (RIM) over Europe is developed. GPS observations from 60 International GNSS Servoce (IGS) and EUREF reference stations are processed in the Bernese-5·2 Precise Point Positioning (PPP) module to estimate the Vertical Total Electron Content (VTEC). The RIM has spatial and temporal resolutions of 1° × 1° and 15 minutes, respectively. The receiver DCBs for three stations from the International GNSS Service Multi-GNSS Experiment (IGS-MGEX) are estimated for three different days. The estimated DCBs are compared with the MGEX published values. The results show agreement with the MGEX values with mean difference and Root Mean Square Error (RMSE) values less than 1 ns. In addition, the combined GPS, BeiDou and Galileo VTEC values are evaluated and compared with the IGS Global Ionospheric Maps (IGS-GIM) counterparts. The results show agreement with the GIM values with mean difference and RMSE values less than 1 Total Electron Content Unit (TECU).
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Iwakawa, Masaya, Kazuo Mizoi, Alan Tessler, and Yasunobu Itoh. "Intraspinal Implants of Fibrin Glue Containing Glial Cell Line-Derived Neurotrophic Factor Promote Dorsal Root Regeneration into Spinal Cord." Neurorehabilitation and Neural Repair 15, no. 3 (September 2001): 173–82. http://dx.doi.org/10.1177/154596830101500304.
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Objective: The purpose of this study was to determine whether glial cell line—de rived neurotrophic factor (GDNF) delivered intraspinally via a fibrin glue (FG) en hanced regeneration of cut dorsal root (DR). Methods: FG containing GDNF was inserted into aspiration cavities in the lumbar enlargement of adult rats. The tran sected L5 DR stump was placed at the bottom of the cavity and sandwiched between the FG and the spinal cord. Regenerated DR axons were labeled with horseradish peroxidase (HRP) or with immunohistochemical methods for calcitonin gene-related peptide (CGRP). Results: Primary afferent axons labeled with HRP regenerated into the spinal cord, received GDNF, and made frequent arborization there. Some of these were myelinated axons that established synapses on intraspinal neuronal profiles. CGRP-immunoreactive DR axons extended into the motor neurons and formed promi nent varicosities around their cell bodies. Only a few axons regenerated into the spinal cords given FG without GONE Conclusions: Our results indicate that GDNF en hances regeneration of DR into the adult rat spinal cord and that GDNF may be ef fectively supplied to the intraspinal injury site via FG. Because the regenerated axons establish synapses on intraspinal neurons, this therapeutic strategy has the potential to help to rebuild spinal reflex circuits interrupted by spinal cord injury. Key Words: GDNF—Fibrin glue—Intraspinal injury—Calcitonin gene-related peptide—Dorsal root regeneration—Electron microscopy—Glial cell line-derived neurotrophic fac tor—Horseradish peroxidase.
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L'Huillier, Laurent, Jean d'Auzac, Monique Durand, and Nicole Michaud-Ferrière. "Nickel effects on two maize (Zea mays) cultivars: growth, structure, Ni concentration, and localization." Canadian Journal of Botany 74, no. 10 (October 1, 1996): 1547–54. http://dx.doi.org/10.1139/b96-187.
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The toxic effects of nickel on maize growth and structure and the accumulation and distribution of Ni in the plant were investigated. Two cultivars of maize, each with a different sensitivity to Ni, were grown on nutrient solution with different nickel concentrations for a period of 8 days. The sensitive and tolerant cultivars exhibited reduction in root and shoot growth with Ni concentrations greater than 20 μM and 40 μM, respectively. The toxic effects of nickel on the structure and ultrastructure of maize roots and leaves were studied by light microscopy and transmission and scanning electron microscopy. With 60 μM Ni, the sensitive cultivar showed a strong reduction in root mitotic activity (80%). Statoliths were absent in cells of the root cap, while leaves contained large amounts of starch in the chloroplasts of their bundle sheath cells. This suggests a decrease in carbohydrate transport between the leaves and the roots. The tissue localization of Ni by the dimethylglyoxim and silver sulphide methods showed important accumulation in the root apex and in the chloroplasts of the bundle sheath cells. These results suggest that Ni reduces maize growth by a reduction in root mitotic activity, probably because of direct action on the meristem. Starch accumulation in the leaves could come directly from a decrease in the root sink effect caused by the reduced mitotic activity or indirectly from an inhibition of carbohydrate transport. Keywords: maize, Ni toxicity, growth, Ni accumulation, Ni distribution, mitotic activity.