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Articoli di riviste sul tema "Bismuth trioxide"

Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 1 febbraio 2022

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1

Wang, Bing, Junhua Wang, Aimin Chang e Jincheng Yao. "Bismuth trioxide-tailored sintering temperature, microstructure and NTCR characteristics of Mn1.1Co1.5Fe0.4O4 ceramics". RSC Advances 9, n. 44 (2019): 25488–95. http://dx.doi.org/10.1039/c9ra04676c.

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2

Leontie, L., M. Caraman, M. Delibaş e G. I. Rusu. "Optical properties of bismuth trioxide thin films". Materials Research Bulletin 36, n. 9 (luglio 2001): 1629–37. http://dx.doi.org/10.1016/s0025-5408(01)00641-9.

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3

Condurache-Bota, Simona, Mirela Praisler, Raluca Gavrila e Nicolae Tigau. "Sandwich heterostructures of antimony trioxide and bismuth trioxide films: Structural, morphological and optical analysis". Applied Surface Science 391 (gennaio 2017): 59–65. http://dx.doi.org/10.1016/j.apsusc.2016.07.033.

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4

Kelly, Zack, e Funsho Ojebuoboh. "Producing bismuth trioxide and its application in fire assaying". JOM 54, n. 4 (aprile 2002): 42–45. http://dx.doi.org/10.1007/bf02701656.

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5

Primathena, Indra, Denny Nurdin, Hendra Hermawan e Arief Cahyanto. "Synthesis, Characterization, and Antibacterial Evaluation of a Cost-Effective Endodontic Sealer Based on Tricalcium Silicate-White Portland Cement". Materials 14, n. 2 (15 gennaio 2021): 417. http://dx.doi.org/10.3390/ma14020417.

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Mineral trioxide aggregate (MTA) is an ideal yet costly endodontic sealer material. Tricalcium silicate-white Portland cement (TS-WPC) seems to have similar characteristics to those of MTA. This work aims to characterize a modified TS-WPC and evaluate its antibacterial properties as a potential endodontic sealer material. The modified TS-WPC was synthesized from a 4:1 mixture of sterilized Indocement TS-WPC and bismuth trioxide using a simple solution method with 99.9% isopropanol. The mixture was stirred until it was homogenous, centrifuged, and dried. The material was then characterized using infrared spectroscopy, X-ray diffraction, and electron microscopy and subjected to antibacterial evaluation against Enterococcus faecalis using a Mueller–Hinton agar inhibition test. The results showed that the material was characterized by main functional groups of hydroxyls, silicate, bismuth trioxide, and tricalcium silicate, like those of a commercial MTA-based sealer, both tested after hydration. Modified TS-WPC before hydration showed similar powder morphology and size to the commercial one, indicating the ease of manipulation. Both materials exhibited antibacterial activity due to calcium dihydroxide’s ability to absorb carbon dioxide, which is essential for the anaerobic E. faecalis, with minimum inhibitory effect and bactericidal concentrations of 12,500 ppm and 25,000 ppm, respectively. The modified TS-WPC has the potential to become a cost-effective alternative endodontic sealer material.

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6

Ismail, Raid A. "Characteristics of Bismuth trioxide film prepared by rapid thermal oxidation". e-Journal of Surface Science and Nanotechnology 4 (2006): 563–65. http://dx.doi.org/10.1380/ejssnt.2006.563.

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7

Liang, Tao-tao, e Xiao-gang Guo. "Remarkably Facile Preparation of Superhydrophobic Functionalized Bismuth Trioxide (Bi2O3) Coatings". Applied Sciences 9, n. 13 (29 giugno 2019): 2653. http://dx.doi.org/10.3390/app9132653.

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Herein, a novel superhydrophobic functionalized nano-Bi2O3 coating is designed and fabricated using electrophoretic assembly deposition (EAD) in the optimal suspension of polyethylene glycol, ethanol, acetylacetone, and surface functionalization. The small size (70 nm, nano-scale) of Bi2O3 particles and uniform distribution make the target film possessing a promising structure for realizing hydrophobic functionalization. Moreover, the hydrophobicity and stability results indicate that the product has a high-water contact angle (CA) of ca. 167° and is kept almost stable after 180 days exposure in the natural environment. These findings will provide new insight into a better design of superhydrophobic functional coatings via this facile method, holding great promise for future various applications.

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8

Puszynski, Jan A., Christopher J. Bulian e Jacek J. Swiatkiewicz. "Processing and Ignition Characteristics of Aluminum-Bismuth Trioxide Nanothermite System". Journal of Propulsion and Power 23, n. 4 (luglio 2007): 698–706. http://dx.doi.org/10.2514/1.24915.

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9

Eberl, Joachim, e Horst Kisch. "Mineralization of Phenol and 4-Chlorophenol Induced by Visible Light and Assisted by Semiconducting β-Bi2O3". Zeitschrift für Naturforschung B 65, n. 3 (1 marzo 2010): 399–404. http://dx.doi.org/10.1515/znb-2010-0325.

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Intensely yellow β -bismuth trioxide in the form of about 41 nm large crystallites has been prepared by thermal decomposition of (BiO)2CO3 at 400 ◦C. From the band gap energy of 2.3 eV obtained under the assumption of an indirect band-to-band transition and the quasi-Fermi level of −0.28±0.02 V (vs. NHE) a valence band edge position of 2.02 V is calculated. This semiconducting oxide assists a Vis light (λ ≥455 nm) aerial mineralization of the aqueous model pollutants phenol and 4-chlorophenol exhibiting maximum rates at a bismuth oxide concentration of 2.0 g L−1. In the absence of oxygen no degradation occurs indicating that β -Bi2O3 does not act as oxidizing agent. The mineralization suffers from photocorrosion of β -Bi2O3 generating a mixture of α-Bi2O3 and various bismuth carbonates as observed upon multiple use of the oxide in the mineralization of phenol.

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10

Liu, Li Hua, Jun Wu, Xin Li e Zhu Qing Gong. "Preparation of High-Purity Nanometer Bismuth Trioxide from Silver-Zinc Slag". Advanced Materials Research 156-157 (ottobre 2010): 785–93. http://dx.doi.org/10.4028/www.scientific.net/amr.156-157.785.

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Silver-zinc slag, containing a lot of Bi, Ag, Cu, Zn, Pb and a little Au, has high comprehensive utilization value. This paper describes a preparation method of high-purity nanometer bismuth trioxide (Bi2O3) from silver-zinc slag by hydrometallurgical method. The results showed that Bi could be effectively leached out from silver-zinc slag using sodium chlorate, hydrochloric acid and sodium chloride as leaching agents, and the leaching rate of Bi was up to 99.03% under the optimum conditions. The contents of Pb2+ and Ag+ in BiCl3 solution could be reduced to about 1mg/L by using silver-zinc slag as reductant and sodium iodide (NaI) as precipitant, respectively. Crystalline form of Bi2O3 is affected greatly by concentration of NaOH, conversion temperature and time. The suitable temperature of BiOCl converting to Bi2O3 was 90 , and the suitable surfactant was polyvinyl alcohol. The average particle size of Bi2O3 obtained was about 86 nm, the purity of Bi2O3 was up to 99.75%, and the yield was 98.21%.

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11

Xia, Nannan, Tianxiang Zhou, Shanshan Mo, Shuangli Zhou, Wujun Zou e Dingsheng Yuan. "A Facile Method to Prepare Nanosheets Bismuth Trioxide for Electrochemical Capacitors". ECS Transactions 28, n. 17 (17 dicembre 2019): 121–25. http://dx.doi.org/10.1149/1.3503358.

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12

Felix, Taís, Orlando P. Pinto, Augusto Peres, João M. Costa, Claudia Sayer, Alexander B. Morgan e Pedro HH Araújo. "Comparison of bismuth trioxide and antimony trioxide as synergists with decabromodiphenyl ether in flame retardancy of high-impact polystyrene". Journal of Fire Sciences 30, n. 6 (6 settembre 2012): 566–74. http://dx.doi.org/10.1177/0734904112456004.

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13

Peng, Tzu-Yu, May-Show Chen, Ya-Yi Chen, Yao-Jui Chen, Chin-Yi Chen, Alex Fang, Bo-Jiun Shao, Min-Hua Chen e Chung-Kwei Lin. "Impact of Zr-Doped Bi2O3 Radiopacifier by Spray Pyrolysis on Mineral Trioxide Aggregate". Materials 14, n. 2 (19 gennaio 2021): 453. http://dx.doi.org/10.3390/ma14020453.

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Abstract (sommario):

Mineral trioxide aggregates (MTA) have been developed as a dental root repair material for a range of endodontics procedures. They contain a small amount of bismuth oxide (Bi2O3) as a radiopacifier to differentiate adjacent bone tissue on radiographs for endodontic surgery. However, the addition of Bi2O3 to MTA will increase porosity and lead to the deterioration of MTA’s mechanical properties. Besides, Bi2O3 can also increase the setting time of MTA. To improve upon the undesirable effects caused by Bi2O3 additives, we used zirconium ions (Zr) to substitute the bismuth ions (Bi) in the Bi2O3 compound. Here we demonstrate a new composition of Zr-doped Bi2O3 using spray pyrolysis, a technique for producing fine solid particles. The results showed that Zr ions were doped into the Bi2O3 compound, resulting in the phase of Bi7.38Zr0.62O12.31. The results of materials analysis showed Bi2O3 with 15 mol % of Zr doping increased its radiopacity (5.16 ± 0.2 mm Al) and mechanical strength, compared to Bi2O3 and other ratios of Zr-doped Bi2O3. To our knowledge, this is the first study of fabrication and analysis of Zr-doped Bi2O3 radiopacifiers through the spray pyrolysis procedure. The study reveals that spray pyrolysis can be a new technique for preparing Zr-doped Bi2O3 radiopacifiers for future dental applications.

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14

Cho, J. H., M. S. Kim e J. D. Rhim. "Comparison of radiation shielding ratios of nano-sized bismuth trioxide and molybdenum". Radiation Effects and Defects in Solids 170, n. 7-8 (3 luglio 2015): 651–58. http://dx.doi.org/10.1080/10420150.2015.1080703.

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15

Öztürk, Esra, e Nilgun Ozpozan Kalaycioglu. "Synthesis and characterization of terbium oxide (III–IV) doped bismuth trioxide polymorphs". Journal of the Chinese Advanced Materials Society 1, n. 2 (giugno 2013): 90–96. http://dx.doi.org/10.1080/22243682.2013.792540.

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16

Cervino, Gabriele, Luigi Laino, Cesare D’Amico, Diana Russo, Ludovica Nucci, Giulia Amoroso, Francesca Gorassini et al. "Mineral Trioxide Aggregate Applications in Endodontics: A Review". European Journal of Dentistry 14, n. 04 (29 luglio 2020): 683–91. http://dx.doi.org/10.1055/s-0040-1713073.

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AbstractA current topic in dentistry concerns the biocompatibility of the materials, and in particular, conservative dentistry and endodontics ones. The mineral trioxide aggregate (MTA) is a dental material with biocompatibility properties to oral and dental tissues. MTA was developed for dental root repair in endodontic treatment and it is formulated from commercial Portland cement, combined with bismuth oxide powder for radiopacity. MTA is used for creating apical plugs during apexification, repairing root perforations during root canal therapy, treating internal root resorption, and pulp capping. The objective of this article is to investigate MTA features from a clinical point of view, even compared with other biomaterials. All the clinical data regarding this dental material will be evaluated in this review article. Data obtained from the analysis of the past 10 years’ literature highlighted 19 articles in which the MTA clinical aspects could be recorded. The results obtained in this article are an important step to demonstrate the safety and predictability of oral rehabilitations with these biomaterials and to promote a line to improve their properties in the future.

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17

Yang, Tzu-Sen, May-Show Chen, Cheng-Jyun Huang, Chin-Yi Chen, Agnese Brangule, Aleksej Zarkov, Aivaras Kareiva, Chung-Kwei Lin e Jen-Chang Yang. "A Novel Sol-Gel Bi2-xHfxO3+x/2 Radiopacifier for Mineral Trioxide Aggregates (MTA) as Dental Filling Materials". Applied Sciences 11, n. 16 (8 agosto 2021): 7292. http://dx.doi.org/10.3390/app11167292.

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Mineral trioxide aggregate (MTA) is well known as an effective root canal filling material for endodontics therapy. Within MTA, bismuth oxide (Bi2O3) serving as the radiopacifier still has biocompatibility concerns due to its mild cytotoxicity. In the present study, we tried to modify the Bi2O3 radiopacifier by doping hafnium ions via the sol-gel process and investigated the effects of different doping ratios (Bi2-xHfxO3+x/2, x = 0–0.3) and calcination temperatures (400–800 °C). We mixed various precursor mixtures of bismuth nitrate (Bi(NO3)3·5H2O) and hafnium sulfate (Hf(SO4)2) and controlled the calcination temperatures. The as-prepared Hf-doped Bi2O3 radiopacifier powders were investigated by thermogravimetric analysis (TGA), X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). Portland cement/radiopacifier/calcium sulfate (75/20/5) were mixed and set by deionized water (powder to water ratio = 3:1). Changes in radiopacity, diametral tensile strength (DTS), and in vitro cell viability of the hydrated MTA-like cement were carried out. The experimental results showed that the group containing radiopacifier from sol-gelled Bi/Hf (90/10) exhibited significantly higher radiopacity (6.36 ± 0.34 mmAl), DTS (2.54 ± 0.29 MPa), and cell viability (84.0±8.1%) (p < 0.05) when compared to that of Bi/Hf (100/0) powders. It is suggested that the formation of β-Bi7.78Hf0.22O12.11 phase with hafnium addition and calcining at 700 °C can prepare novel bismuth/hafnium composite powder that can be used as an alternative radiopacifier for root canal filling materials.

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18

Gómez-Torres, X., M. Esquivel-Gaón, D. J. López-Ventura, S. Treviño, L. M. Del Razo, O. Barbier e A. De Vizcaya-Ruiz. "Subchronic exposure to bismuth trioxide nanoparticles induces mild nephrotoxicity in male Wistar rats". Toxicology Letters 259 (ottobre 2016): S242—S243. http://dx.doi.org/10.1016/j.toxlet.2016.07.582.

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19

Sekkina, M. M. Abou, e E. El-Shereafy. "Spectral properties and temperature-dependence of semiconductivity of various doped bismuth trioxide polycrystals". Journal of Thermal Analysis 32, n. 4 (luglio 1987): 1209–18. http://dx.doi.org/10.1007/bf01905175.

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20

HU, Han-xiang, Ke-qiang QIU e Guo-fu XU. "Preparation of nanometer δ- and β-bismuth trioxide by vacuum vapor-phase oxidation". Transactions of Nonferrous Metals Society of China 16, n. 1 (febbraio 2006): 173–77. http://dx.doi.org/10.1016/s1003-6326(06)60031-9.

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21

Martirosyan, K. S., L. Wang, A. Vicent e D. Luss. "Synthesis and performance of bismuth trioxide nanoparticles for high energy gas generator use". Nanotechnology 20, n. 40 (14 settembre 2009): 405609. http://dx.doi.org/10.1088/0957-4484/20/40/405609.

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22

Wang, Yue, Yan-Jun Liu, Shao-Yang Li, Mao Ye, Yin-Hua Shao, Rong Wang, Li-Feng Guo, Cui-E. Zhao e Ang Wei. "Low Temperature Synthesis of Tungsten Trioxide/Bismuth Tungstate Heterojunction with Enhanced Photocatalytic Activity". Journal of Nanoscience and Nanotechnology 17, n. 8 (1 agosto 2017): 5520–24. http://dx.doi.org/10.1166/jnn.2017.13812.

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23

Al-Ghamdi, A. A., Yusuf Al-Turki, Nadia Abdel Aal, Fahrattin Yakuphanoglu e Farid El-Tantawy. "Microwave—assisted hydrothermal synthesis of monoclinic bismuth trioxide nanorods: optical and photocatalytic properties". Journal of Materials Science: Materials in Electronics 28, n. 12 (3 marzo 2017): 8684–93. http://dx.doi.org/10.1007/s10854-017-6593-3.

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24

Grazziotin-Soares, R., M. H. Nekoofar, T. E. Davies, A. Bafail, E. Alhaddar, R. Hübler, A. L. S. Busato e P. M. H. Dummer. "Effect of bismuth oxide on white mineral trioxide aggregate: chemical characterization and physical properties". International Endodontic Journal 47, n. 6 (12 settembre 2013): 520–33. http://dx.doi.org/10.1111/iej.12181.

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25

Cheng, Junfeng, Jun Zhou, Zhixiong Lin, Dun Wu, Chunlin Liu, Zheng Cao, Qingting Ni e Ning Zhang. "Locally controllable laser patterning transfer of thermoplastic polyurethane induced by sustainable bismuth trioxide substrate". Applied Surface Science 550 (giugno 2021): 149299. http://dx.doi.org/10.1016/j.apsusc.2021.149299.

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26

BOUCHAREB, FATIMA ZOHRA, e NASR-EDDINE HAMDADOU. "ANNEALING EFFECT ON STRUCTURAL AND OPTICAL PROPERTIES OF COPPER-DOPED BISMUTH TRIOXIDE Cu:Bi2O3 THIN FILMS". Surface Review and Letters 27, n. 07 (25 novembre 2019): 1950174. http://dx.doi.org/10.1142/s0218625x19501749.

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Abstract (sommario):

In this work, we have examined the effect of annealing temperature on Cu-doped Bi2O3 thin films at 1%, 3% and 5% doping rate successfully prepared by spray pyrolysis technique onto glass substrates. The obtained films were subsequently annealed at different temperature for 4[Formula: see text]h. GIXRD analysis reveals the polycrystalline nature of deposited films and shows the formation of mixed [Formula: see text]- and [Formula: see text]-Bi2O3 phases. With the increase of doping rate, [Formula: see text]-phase of Bi2O3 was identified at medium temperature. The average grain size of thin films at different doping rate of Cu decreases with the increase of annealing temperature. The optical characterization shows that the optical transmittance of the films decreases with the increase of annealing temperature in the range (70–50%) and (40–10%) for 1% and 5% doping rate of Cu, respectively. The evaluation of the optical bandgap energy reveals that the indirect transition is controlling the optical response of the films. The optimum annealing temperature to reduce Bi2O3 energy bandgap to be 3.09[Formula: see text]eV, is 450∘C and 550∘C for 3% and 5% doping rate of Cu.

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27

MIURA, Yasuyuki, e Tomozo KOH. "Spectrophotometric determination of micro amounts of manganese(II) via its oxidation by sodium bismuth trioxide." Bunseki kagaku 35, n. 6 (1986): 524–29. http://dx.doi.org/10.2116/bunsekikagaku.35.6_524.

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Thiruvengadathan, Rajagopalan, Clay Staley, Jordan M. Geeson, Stephen Chung, Kristofer E. Raymond, Keshab Gangopadhyay e Shubhra Gangopadhyay. "Enhanced Combustion Characteristics of Bismuth Trioxide-Aluminum Nanocomposites Prepared through Graphene Oxide Directed Self-Assembly". Propellants, Explosives, Pyrotechnics 40, n. 5 (16 aprile 2015): 729–34. http://dx.doi.org/10.1002/prep.201400238.

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Li, Li, Xiandan Huang, Jianqi Zhang, Wenzhi Zhang, Fengyan Ma, Zhixin Xiao, Shuang Gai, Dandan Wang e Na Li. "Multi-layer three-dimensionally ordered Bismuth trioxide/Titanium dioxide nanocomposite: Synthesis and enhanced photocatalytic activity". Journal of Colloid and Interface Science 443 (aprile 2015): 13–22. http://dx.doi.org/10.1016/j.jcis.2014.11.062.

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30

Bhutani, M. M., e Ramesh Kumari. "Adsorption of low level51Cr(VI) from aqueous solution by bismuth trioxide: Kinetic and IR study". Journal of Radioanalytical and Nuclear Chemistry Articles 180, n. 1 (maggio 1994): 145–53. http://dx.doi.org/10.1007/bf02039913.

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Mandai, Shinya, Kazushi Kinugasa e Takashi Ohmoto. "Direct thrombosis of aneurysms with cellulose acetate polymer". Journal of Neurosurgery 77, n. 4 (ottobre 1992): 497–500. http://dx.doi.org/10.3171/jns.1992.77.4.0497.

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✓ The authors have developed a liquid material for thrombosing aneurysms. This material is a mixture of cellulose acetate polymer and bismuth trioxide dissolved in dimethyl sulfoxide. On contact with blood, the dimethyl sulfoxide diffuses and cellulose acetate polymer forms, which balloons when slowly injected into the blood. The polymer solidifies from surface to core in 5 minutes. Cellulose acetate polymer was injected directly into experimental aneurysms created in 10 dogs; it rapidly hardened in the shape of the aneurysms, completely obliterating them but preserving the parent vessels in all cases. No distal migration of the polymer was seen. The good results of this experimental trial led to a clinical study using a cellulose acetate polymer, as described in Part II.

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32

Fa'izzah, Maulidia, Widjijono Widjijono, Yuichi Kamiya e Nuryono Nuryono. "Synthesis and Characterization of White Mineral Trioxide Aggregate Using Precipitated Calcium Carbonate Extracted from Limestone". Key Engineering Materials 840 (aprile 2020): 330–35. http://dx.doi.org/10.4028/www.scientific.net/kem.840.330.

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White Mineral Trioxide Aggregate (WMTA) using precipitated CaCO3 (PCC) from limestone has been synthesized. PCC in calcite structure was extracted from limestone by calcination at 900 °C for 3 h, dissolved in 0.8 M nitric acid solution and followed with carbonation for 60 minutes. PCC was used for the synthesis of WMTA by mixing with tetraethoxyorthosilicate, bismuth oxide, aluminum oxide, catalyst of with HNO3 and NH3 solution and thermally treated at 1100 °C for 3 h. The products were characterized with Thermal Gravimetric Analysis-Differential Thermal Analysis (TGA-DTG), X-ray Diffraction (XRD), Frontier-Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM) and X-ray Fluorescence (XRF). The results showed that the PCC dominated calcite structure was obtained with 75.25% in yield and 99.42% in purity. The WMTA has been successfully synthesized by low thermal treatment at 1100 °C using catalysts of HNO3 and NH3 solution, proven by the presence of tricalcium silicate (C3S), dicalcium silicate (C2S), tricalcium aluminate (C3A), and Bi2O3 in WMTA.

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Oliveira, Marília Gerhardt de, Cristina Braga Xavier, Flávio Fernando Demarco, Antônio Luis Barbosa Pinheiro, Aline Tempel Costa e Daniel Humberto Pozza. "Comparative chemical study of MTA and portland cements". Brazilian Dental Journal 18, n. 1 (2007): 3–7. http://dx.doi.org/10.1590/s0103-64402007000100002.

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Portland cement has been analyzed and compared to mineral trioxide aggregate (MTA) because of their chemical similarity. The possibility of using this material as a less expensive alternative to MTA in dental practice should be considered. In view of this, the present study compared the components of a Portland cement (Votoran®) to two commercial brands of MTA (Pro-Root™ and MTA-Angelus®). Twelve specimens of each material were fabricated and examined by scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) to obtain their percentage of chemical elements. The means of the chemical elements found in each material was compared by descriptive statistics. Bismuth was present only in MTA cements to provide radiopacity. In conclusion, the tested cements have similar components, which supports, as far as composition is concerned, the possible clinical use of Portland as an option to MTA.

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Sayed, Mostafa Saad, Debananda Mohapatra, Marjorie Lara Baynosa e Jae‐Jin Shim. "Three-dimensional core-shell heterostructure of tungsten trioxide/bismuth molybdate/cobalt phosphate for enhanced photoelectrochemical water splitting". Journal of Colloid and Interface Science 598 (settembre 2021): 348–57. http://dx.doi.org/10.1016/j.jcis.2021.03.105.

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Chen, May-Show, Hsiu-Na Lin, Yu-Chun Cheng, Alex Fang, Chin-Yi Chen, Pee-Yew Lee e Chung-Kwei Lin. "Effects of Milling Time, Zirconia Addition, and Storage Environment on the Radiopacity Performance of Mechanically Milled Bi2O3/ZrO2 Composite Powders". Materials 13, n. 3 (24 gennaio 2020): 563. http://dx.doi.org/10.3390/ma13030563.

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Abstract (sommario):

Mineral trioxide aggregate (MTA) typically consists of Portland cement (75 wt.%), bismuth oxide (20 wt.%), and gypsum (5 wt.%) and is commonly used as endodontic cement. Bismuth oxide serving as the radiopacifying material reveals the canal filling effect after clinical treatment. In the present study, bismuth/zirconium oxide composite powder was prepared by high energy ball milling of (Bi2O3)100−x (ZrO2)x (x = 5, 10, 15, and 20 wt.%) powder mixture and used as the radiopacifiers within MTA. The crystalline phases of the as-milled powders were examined by the X-ray diffraction technique. The radiopacities of MTA-like cements prepared by using as-milled composite powders (at various milling stages or different amount of zirconia addition) were examined. In addition, the stability of the as-milled powders stored in an ambient environment, an electronic dry box, or a glove box was investigated. The experimental results show that the as-milled powder exhibited the starting powder phases of Bi2O3 and ZrO2 and the newly formed δ-Bi7.38Zr0.62O2.31 phase. The longer the milling time or the larger the amount of the zirconia addition, the higher the percentage of the δ-Bi7.38Zr0.62O2.31 phase in the composite powder. All the MTA-like cements prepared by the as-milled powder exhibited a radiopacity higher than 4 mmAl that is better than the 3 mmAl ISO standard requirement. The 30 min as-milled (Bi2O3)95(ZrO2)5 composite powder exhibited a radiopacity of 5.82 ± 0.33 mmAl and degraded significantly in the ambient environment. However, storing under an oxygen- and humidity-controlled glove box can prolong a high radiopacity performance. The radiopacity was 5.76 ± 0.08 mmAl after 28 days in a glove box that was statistically the same as the original composite powder.

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Jenkins, R. O., T.-A. Morris, P. J. Craig, W. Goessler, N. Ostah e K. M. Wills. "Evaluation of cot mattress inner foam as a potential site for microbial generation of toxic gases". Human & Experimental Toxicology 19, n. 12 (dicembre 2000): 693–702. http://dx.doi.org/10.1191/096032700670028460.

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Abstract (sommario):

Recent reports of biovolatilisation of phosphorus and antimony by anaerobic bacteria and of leaching of phosphorus and antimony fire-retardant additives from PVC cot mattress covers, indicate that the polyurethane inner-foam of cot mattresses could be a site for generation of toxic gases of group 15 elements. A toxic gas hypothesis for sudden infant death syndrome (SIDS) involving polyurethane foam of cot mattresses was proposed and tested experimentally. Levels of antimony, phosphorus, arsenic and bismuth were determined at four sites for 44 SIDS and 50 control (no death) cot mattress foams. There was no evidence to suggest that the levels of these elements in cot mattress foam have a causal relation to SIDS. Leaching of antimony trioxide from PVC mattress covers could account for detectable levels of this element in 52% of the cot mattress samples analysed. Volatile forms of antimony, phosphorus, arsenic and bismuth was not detected in the headspace of mixed or monoseptic cultures of anaerobic bacteria containing polyurethane foam. Past microbial activity had given rise to involatile methylated species of antimony in some of the cot mattress foams tested (61%, n = 24). Abiotic oxidation of biogenic trimethylatimony together with physical adsorption of methylantmony forms to the polyurethane foam matrix could account for the apparent absence of “escaped” volatile antimony species in culture headspaces of incubation vial. There was no evidence to suggest that levels of trimethylantimony or total methylantimony forms in cot mattress foams have a causal relation to SIDS.

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37

Caliskan, Secil, Nuray Tuloglu e Sule Bayrak. "Clinical applications of BioAggregate in pediatric dentistry: Case reports". Srpski arhiv za celokupno lekarstvo 147, n. 11-12 (2019): 746–50. http://dx.doi.org/10.2298/sarh190509124c.

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Abstract (sommario):

Introduction. Calcium-silicate-based, nanoparticle-sized BioAggregate is produced as an alternative version of mineral trioxide aggregate (MTA). It contains additives such as calcium phosphate and silicon dioxide but does not contain aluminium oxide and bismuth oxide. Studies have shown that BioAggregate?s calcium-ion release is better than these qualities in MTA concerning fracture and acid resistance, biocompatibility and sealing ability. Case outline. In this paper, we examine eight case reports. These reports describe the long-term results of using BioAggregate in areas such as pulpotomy and root canal treatment in primary and permanent teeth, partial pulpotomy, artificial apical barrier construction of permanent teeth, root resorption repair, and treatment of dens in dente. Conclusion. As evidenced by the case reports examined here, BioAggregate can be used as alternative material to MTA in many dental treatments. These reports also show that the biocompatibility, antibacterial properties, hardening when moisture is present, ideal expansion percentage, impermeability, and dentine adhesion features of BioAggregate provide advantages in clinical use.

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Den, Rethy, Rini Dharmastiti, Nuryono Nuryono, Leny Yuliatun e Widjijono Widjijono. "Effect of Varying Water-to-Powder Ratios on Compressive Strength and Porosity of Mineral Trioxide Aggregate". Key Engineering Materials 840 (aprile 2020): 345–50. http://dx.doi.org/10.4028/www.scientific.net/kem.840.345.

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Abstract (sommario):

The proportion of MTA powder and water is a common factor impacted on the properties of the material in clinical application. The purpose of this research was to determine the compressive strength and porosity of Mineral Trioxide Aggregate (MTA) mixed with varying water-to-powder (WP) ratios. ROOTDENT MTA was investigated. One gram of cement was mixed with 0.28, 0.33 or 0.40 grams of distilled water and was submerged either for 1, 7, or 28 days in the water. The chemical composition of un-hydrated MTA was characterized by X-ray fluorescence. Samples were carried out for compression and porosity test. ROOTDENT MTA was composed primarily of calcium, oxygen, and zirconium. Minor quantities of sodium, aluminum, and silicon were presented in the cement and lack of bismuth was found. The highest mean compressive strength value was MTA with 0.33 WP ratio submerged in the water for 28 days. The percentage of porosity increased as the WP ratio increased. The percentage of porosity submerged in the water for 7 and 28 days showed no significant differences while the lowest porosity was MTA with 1 day in the water.

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Marciano, Marina Angélica, Reginaldo Mendonça Costa, Josette Camilleri, Rafael Francisco Lia Mondelli, Bruno Martini Guimarães e Marco Antonio Hungaro Duarte. "Assessment of Color Stability of White Mineral Trioxide Aggregate Angelus and Bismuth Oxide in Contact with Tooth Structure". Journal of Endodontics 40, n. 8 (agosto 2014): 1235–40. http://dx.doi.org/10.1016/j.joen.2014.01.044.

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40

Fuku, Kojiro, e Kazuhiro Sayama. "Efficient oxidative hydrogen peroxide production and accumulation in photoelectrochemical water splitting using a tungsten trioxide/bismuth vanadate photoanode". Chemical Communications 52, n. 31 (2016): 5406–9. http://dx.doi.org/10.1039/c6cc01605g.

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41

Güngör, A., İ. K. Akbay, D. Yaşar e T. Özdemir. "Flexible X/Gamma ray shielding composite material of EPDM rubber with bismuth trioxide: Mechanical, thermal investigations and attenuation tests". Progress in Nuclear Energy 106 (luglio 2018): 262–69. http://dx.doi.org/10.1016/j.pnucene.2018.03.021.

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42

Zhang, Mengmeng, Youyi Zhu, Wenjun Li, Fangzhi Wang, Hongda Li, Xintong Liu, Weiwei Zhang e Chaojun Ren. "Double Z-scheme system of silver bromide@bismuth tungstate/tungsten trioxide ternary heterojunction with enhanced visible-light photocatalytic activity". Journal of Colloid and Interface Science 509 (gennaio 2018): 18–24. http://dx.doi.org/10.1016/j.jcis.2017.08.095.

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43

Ploska, Ute, Georg Berger e Manfred Willfahrt. "Dense Sintered Long-Term Stable Ceramics in the System CaO-P₂O₅-ZrO₂-F". Key Engineering Materials 309-311 (maggio 2006): 267–70. http://dx.doi.org/10.4028/www.scientific.net/kem.309-311.267.

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Abstract (sommario):

The influence of several sinter additives (three glasses, magnesium acetate, bismuth trioxide) on the compressive strength and also on the solubility of a sintered ceramics, which is composed of 57.6Mol% CaO, 26.2Mol% P2O5, 10.4Mol% ZrO2 and 5.8Mol% CaF2 was tested. The amount of sinter additives, pre-mixing of the powders, pressure power, sintering temperature and sintering time were varied. The most dense samples were produced with the finest powders (D50 ~ 1/m) and the highest sintering temperatures (1200°C). The mechanical stability of the samples was more influenced by the particle size of the powders than by the kind of binder as well as the pressure power. The compressive strength of the sintered samples ranged between 180MPa (D50 of the powder = 2.4/m) and 530MPa (D50 of the powder < 1/m). Storing of the samples in simulated body fluid for 4 weeks at a temperature of 37°C did not influence the compressive strength significantly. The sintered ceramics can be finished, for instance by grinding or polishing.

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44

Yuan, Ying, Baoqun Geng, Tao Sun, Qingbo Yu e Haifu Wang. "Impact-Induced Reaction Characteristic and the Enhanced Sensitivity of PTFE/Al/Bi2O3 Composites". Polymers 11, n. 12 (10 dicembre 2019): 2049. http://dx.doi.org/10.3390/polym11122049.

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Abstract (sommario):

In this paper, the reaction characteristic of a novel reactive material, which introduced bismuth trioxide (Bi2O3) into traditional polytetrafluoroethylene/aluminum (PTFE/Al), is studied. The effect of Bi2O3 with different content and particle size on the reaction behaviors of PTFE/Al/Bi2O3 are investigated by drop-weight test and X-ray diffractometer (XRD), including impact sensitivity, energy release performance under a certain impact, and reaction mechanism. The experimental results show that the content of Bi2O3 increased from 0% to 35.616%, the characteristic drop height of impact sensitivity (H50) of PTFE/Al/Bi2O3 reactive materials decreased first and then increased, and the minimum H50 of all types of materials in the experiment is 0.74 times that of PTFE/Al, and the particle size of Bi2O3 affects the rate of H50 change with Bi2O3 content. Besides, with the increase of Bi2O3 content, both the reaction intensity and duration first increase and then decrease, and there is optimum content of Bi2O3 maximizing the reaction degree of the PTFE/Al/Bi2O3. Furthermore, a prediction model for the impact sensitivity of PTFE-based reactive material is developed. The main reaction products include AlF3, xBi2O3·Al2O3, and Bi.

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45

Nie, Yuhan, Yadong Xie, Ying Zheng, Yao Luo, Jianguo Zhang, Zao Yi, Fusheng Zheng et al. "Preparation of ZnO/Bi2O3 Composites as Heterogeneous Thin Film Materials with High Photoelectric Performance on FTO Base". Coatings 11, n. 9 (20 settembre 2021): 1140. http://dx.doi.org/10.3390/coatings11091140.

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Abstract (sommario):

In recent years, ZnO nanomaterials have achieved great performance in solar energy applications. How to synthesize a ZnO nanocomposite structure with high photoelectric conversion efficiency has become an urgent problem to solved. In this paper, a narrow band gap bismuth trioxide (Bi2O3) coated on a ZnO nanoarray by magnetron sputtering was used to prepare a composite heterojunction ZnO/Bi2O3. Studies have found that ZnO/Bi2O3 exhibits excellent photoelectric conversion performance. By preparing a composite heterostructure of ZnO/Bi2O3, it can effectively compensate for the insufficient absorption of ZnO in the visible light range and inhibit the recombination of carriers within the material. The influence of Bi2O3 thickness on the microstructure and electronic structure of the ZnO/Bi2O3 composite structure was explored and analyzed. The energy gap width of the composite heterostructure decreases with the increase in the Bi2O3 thickness on the surface of the ZnO nanorod array. At the same time, the conductive glass composite film structure is simple to prepare and is very environmentally friendly. The ZnO/Bi2O3 composite heterogeneous material prepared this time is suitable for solar cells, photodetectors, photocatalysis and other fields.

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46

Coomaraswamy, K. S., P. J. Lumley, R. M. Shelton e M. P. Hofmann. "Evaluation of Different Radiopacifiers for an MTA-Like Dental Cement". Key Engineering Materials 361-363 (novembre 2007): 885–88. http://dx.doi.org/10.4028/www.scientific.net/kem.361-363.885.

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Abstract (sommario):

The present study evaluated the influence of different radiopacifiers on an established mineral trioxide aggregate (MTA)-like Portland cement system. Commercial MTA contains bismuth oxide (Bi2O3) as the radiopacifier and inert alternatives tested were barium sulphate (BaSO4), lanthanum oxide (La2O3) and tantalum pentoxide (Ta2O5). The radiopacity of the different formulations was measured with densitometry, whilst relative porosity was determined using helium pycnometry and compressive strength was measured as an indicator for the potential longevity of the alternative cement formulations. At 20wt% radiopacifier content the order of radiopacity was, Bi2O3 (3.71mm Aluminium equivalent), Ta2O5 (2.76mm Al), La2O3 (1.85mm Al) and BaSO4 (1.48mm Al). The commercial MTA control had a radiopacity of 3.65mm Al. The addition of all radiopacifiers caused a deterioration in strength and increased porosity; the incorporation of 20wt% Bi2O3 reduced strength from 68MPa by 36%. Ta2O5-containing cement had a strength comparable with that containing Bi2O3 (43MPa), whilst La2O3 and BaSO4 addition generated even weaker cements. Commercial MTA had a similar strut density to the Bi2O3- containing model system although had a lower strength (34MPa) due to its higher porosity. Bi2O3 appeared to be the best of the investigated radiopacifiers for this endodontic filling material as it provided the highest mechanical stability, lowest porosity and was the most radiopaque.

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47

Ke, Jun, Hong-Ru Zhou, Yuan-Yuan Peng e Di-Yong Tang. "In Situ Construction of a Two-Dimensional Heterojunction by Stacking Bismuth Trioxide Nanoplates with Reduced Graphene Oxide for Enhanced Water Oxidation Performance". Journal of Nanoscience and Nanotechnology 19, n. 9 (1 settembre 2019): 5554–61. http://dx.doi.org/10.1166/jnn.2019.16568.

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48

Tokunaga, K., K. Kinugasa, T. Meguro, S. Kawada, K. Sugiu, H. Nakashima, T. Furuta et al. "Embolization of Cerebral Arteriovenous Malformations with Cellulose Acetate Polymer". Interventional Neuroradiology 4, n. 1_suppl (novembre 1998): 117–20. http://dx.doi.org/10.1177/15910199980040s125.

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Abstract (sommario):

To test the usefulness of a cellulose acetate polymer(CAP) solution for brain arteriovenous malformations (AVMs), we analyzed the clinical and histological results of patients with AVMs embolized using CAP solution. We reviewed the cases of six patients with cerebral AVMs treated by embolization prior to surgical resection. We used two types of CAP solutions, CAP-M and CAP-L, which are mixtures of 250 mg of solid CAP and 1800 or 2250 mg of bismuth trioxide dissolved in 5.5 or 7.0 ml of dimethyl sulfoxide, respectively. All patients underwent surgical resection 1 to 37 days after the embolization procedure. Resected specimens were fixed in formalin and stained for light microscopic examination. Eighteen feeding vessels were embolized. The reduction rate of the nidus volume was between 20% and nearly 100%. Mild ischemic deficits occurred in one patients but there were no hemorrhagic complications related to the embolization procedures. All AVMs were completely resected by surgery. Direct inspection at surgery revealed that there was no apparent swelling or hematomas in the normal brain areas adjacent to the nidus, and the AVMs were soft enough to be easily retracted. The histological examinations disclosed no or mild inflammatory reactions within two weeks after embolization. The internal elastic lamina was preserved in every case. Recanalization of embolized vessels was not observed until 37 days after embolization. CAP solution is a safe and useful embolic agent for brain AVMs. Further study is needed to resolve the issue of recanalization.

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49

Uemura, Yohei, Toshihiko Yokoyama, Tetsuo Katayama, Shunsuke Nozawa e Kiyotaka Asakura. "Tracking the Local Structure Change during the Photoabsorption Processes of Photocatalysts by the Ultrafast Pump-Probe XAFS Method". Applied Sciences 10, n. 21 (4 novembre 2020): 7818. http://dx.doi.org/10.3390/app10217818.

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Abstract (sommario):

The birth of synchrotron radiation (SR) facilities and X-ray free electron lasers (XFELs) has led to the development of new characterization tools that use X-rays and opened frontiers in science and technology. Ultrafast X-ray absorption fine structure (XAFS) spectroscopy for photocatalysts is one such significant research technique. Although carrier behavior in photocatalysts has been discussed in terms of the band theory and their energy levels in reciprocal space (k-space) based on optical spectroscopic results, it has rarely been discussed where photocarriers are located in real-space (r-space) based on direct observation of the excited states. XAFS provides information on the local electronic and geometrical structures around an X-ray-absorbing atom and can address photocarrier dynamics in the r-space observed from the X-ray-absorbing atom. In this article, we discuss the time dependent structure change of tungsten trioxide (WO3) and bismuth vanadate (BiVO4) photocatalysts studied by the ultrafast pump-probe XAFS method in the femtosecond to nanosecond time scale with the Photon Factory Advanced Ring (PF-AR) and the SPring-8 Angstrom Compact free-electron LAser (SACLA). WO3 shows a femtosecond decay process of photoexcited electrons followed by a structural change to a metastable state with a hundred picosecond speed, which is relaxed to the ground-state structure with a nanosecond time constant. The Bi L3 edge of BiVO4 shows little contribution of the Bi 6s electron to the photoabsorption process; however, it is sensitive to the structural change induced by the photoexcited electron. Time-resolved XAFS measurements in a wide range time domain and with varied wavelengths of the excitation pump laser facilitate understanding of the overall details regarding the photocarrier dynamics that have a significant influence on the photocatalytic performance.

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Nunes, Teresa G. "Influence of Grain Size on the Setting of Portland Cement: A Stray-Field Magnetic Resonance Imaging Study". Materials Science Forum 514-516 (maggio 2006): 1633–37. http://dx.doi.org/10.4028/www.scientific.net/msf.514-516.1633.

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Abstract (sommario):

A number of failures of large concrete structures during construction have been reported in the last decades [1]. The overestimation of concrete strength at early ages was one of the reasons for the failures. Consequently, reliable information about early age properties of the material is essential to guarantee life-time performance of structures. Portland cement is a complex heterogeneous particulate material and a full knowledge of kinetics of the hydration reactions, for example, is still missing. Gel constitutes the major phase in the hardening cement paste and the corresponding structure and dynamics represent an important contribution to determine the concrete performance. X-ray diffraction, which is widely used for the study of crystalline cement components, does not give information about the gel, amorphous, phase. Conversely, 1H stray-field magnetic resonance imaging (STRAFI-MRI) technique has proved to be a powerful tool to follow the early hydration and hardening periods of Portland cement (type I) [2-4]. The setting of cement pastes depends on parameters like the initial water/cement ratio, R, or particle size of the powder (G) and the compressive strength can be used to characterize the behaviour of hardening concrete. Water availability at the particle surfaces, which is controlled by R and G, limits cement hydration. At low R, G effects are less important. In general, it is accepted that for R<0.42, unreacted solid remain, as all the free volume is filled with hydration products [5]. For example, hydration of Portland cement pastes as a function of R (0.24-0.48) was studied using by STRAFI-MRI and hydrogen maps, from different types of water (capillary, gel or chemically bound water), enabled a spatially-resolved kinetics to be obtained [4]. Using STRAFI-MRI was now evaluated the influence of G (<70 μm to < 90 μm) on the early stages of hydration and hardening of Portland cement. Portland cement uses extend well beyond construction. For example, a mineral trioxide aggregate is now being applied as a root-end filling material, which was shown to have a similar chemical constitution to that of Portland cement except for the addition of bismuth compounds, seemingly to make the materials radiopaque for dental use [6].

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