Articoli di riviste: "Nitrure de Bore hexagonale"

1

Yallese, Mohamed Athmane, Lakhdar Boulanouar e Kamel Chaoui. "Usinage de l'acier 100Cr6 trempé par un outil en nitrure de bore cubique". Mécanique & Industries 5, n. 4 (luglio 2004): 355–68. http://dx.doi.org/10.1051/meca:2004036.

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Greco, M., C. Guimon, M. Loudet e G. Pfister-Guillouzo. "Étude par XPS et calculs ab initio de couches minces de nitrure de bore". Journal de Chimie Physique 91 (1994): 1711–27. http://dx.doi.org/10.1051/jcp/199491711.

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Matar, S., V. Gonnet e G. Dernazeau. "Structure électronique du nitrure de bore cubique dans l'approximation de la densité électronique locale". Journal de Physique I 4, n. 2 (febbraio 1994): 335–42. http://dx.doi.org/10.1051/jp1:1994141.

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Djouadi, A., D. Bouchier e M. Lambertin. "Effets thermiques et collisionnels sur les contraintes internes de films de nitrure de bore déposés sous assistance ionique." Revue de Métallurgie 91, n. 9 (settembre 1994): 1283. http://dx.doi.org/10.1051/metal/199491091283.

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Perçin, Ali, Aliekber Yapar, Mehmet Ali Tokgöz, Semih Yaş, Alim Can Baymurat e Hakan Yusuf Selek. "Effects of hexagonal boron nitride on mechanical properties of bone cement (Polymethylmethacrylate)". Joint Diseases and Related Surgery 35, n. 2 (26 febbraio 2024): 340–46. http://dx.doi.org/10.52312/jdrs.2024.1513.

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6

Islamov, D. R., T. V. Perevalov, A. A. Gismatulin, I. A. Azarov, E. V. Spesivtsev e V. A. Gritsenko. "Mekhanizm poperechnogo transporta zaryada v tonkikh plenkakh geksagonal'nogo nitrida bora". Журнал экспериментальной и теоретической физики 163, n. 3 (15 marzo 2023): 392–400. http://dx.doi.org/10.31857/s0044451023030112.

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A mechanism of transverse charge transfer through hexagonal boron nitride (h-BN) in a MIS structure has been studied. Experimental data for charge transfer have been analyzed in terms of different models of charge transfer in insulators. It has been shown that charge transfer in h-BN is described by the model of phonon-assisted tunneling between neutral traps. The thermal and optical energies of phonon-coupled traps in h-BN have been determined. Based on charge transfer measurements, XPS spectra, and the ab initio electronic structure of intrinsic defects in h-BN it has been found that boron–nitrogen divacancies are most probably responsible for charge transfer in h-BN and transfer is provided by electrons.

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Faksawat, Kridsada, Supphadate Sujinnapram, Pichet Limsuwan, Ekachai Hoonnivathana e Kittisakchai Naemchanthara. "Preparation and Characteristic of Hydroxyapatite Synthesized from Cuttlefish Bone by Precipitation Method". Advanced Materials Research 1125 (ottobre 2015): 421–25. http://dx.doi.org/10.4028/www.scientific.net/amr.1125.421.

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Calcium phosphates ceramics such as a hydroxyapatite have composition and structure similar to be mineral component of bone. Hydroxyapatite could be production from natural and chemical source with various techniques. In this study, Calcium phosphates was prepared and characterized for future applications on the utilization of bioactivity and resorbability of Hydroxyapatite. Hydroxyapatite was synthesized by precipitation method using cuttlefish bone as the calcium (Ca) source in the form of calcium nitrate and ammonium phosphate as the phosphate (P) source. The property, crystal structure and crystalline size of samples were investigated by X-ray diffraction (XRD) and Fourier transforms infrared spectroscopy (FTIR). The results showed that the raw cuttlefish bone was calcite and aragonite phase and completely transformed to calcium oxide at 1000 °C. Hydroxyapatite from cuttlefish bone was hexagonal phase. The crystalline size of hydroxyapatite increases with increasing temperature from 200-1300 °C. This experiment indicated that the hydroxyapatite could be synthetized from cuttlefish bone.

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Aki, Deniz, Songul Ulag, Semra Unal, Mustafa Sengor, Nazmi Ekren, Chi-Chang Lin, Hakan Yılmazer, Cem Bulent Ustundag, Deepak M. Kalaskar e Oguzhan Gunduz. "3D printing of PVA/hexagonal boron nitride/bacterial cellulose composite scaffolds for bone tissue engineering". Materials & Design 196 (novembre 2020): 109094. http://dx.doi.org/10.1016/j.matdes.2020.109094.

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9

Angleraud, B., J. Aubreton e A. Catherinot. "Étude de l'expansion du panache plasma formé lors de l'interaction entre un laser ultraviolet et une cible de nitrure de bore ; application à la réalisation de couches minces". Annales de Physique 22 (febbraio 1997): C1–121—C1–122. http://dx.doi.org/10.1051/anphys/1997022.

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Ensoylu, Mertcan, Aylin M. Deliormanlı e Harika Atmaca. "Preparation, Characterization, and Drug Delivery of Hexagonal Boron Nitride-Borate Bioactive Glass Biomimetic Scaffolds for Bone Tissue Engineering". Biomimetics 8, n. 1 (26 dicembre 2022): 10. http://dx.doi.org/10.3390/biomimetics8010010.

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In this study, biomimetic borate-based bioactive glass scaffolds containing hexagonal boron nitride hBN nanoparticles (0.1, 0.2, 0.5, 1, and 2% by weight) were manufactured with the polymer foam replication technique to be used in hard tissue engineering and drug delivery applications. To create three-dimensional cylindrical-shaped scaffolds, polyurethane foams were used as templates and covered using a suspension of glass and hBN powder mixture. Then, a heat treatment was applied at 570 °C in an air atmosphere to remove the polymer foam from the structure and to sinter the glass structures. The structural, morphological, and mechanical properties of the fabricated composites were examined in detail. The in vitro bioactivity of the prepared composites was tested in simulated body fluid, and the release behavior of gentamicin sulfate and 5-fluorouracil from glass scaffolds were analyzed separately as a function of time. The cytotoxicity was investigated using osteoblastic MC3T3-E1 cells. The findings indicated that the hBN nanoparticles, up to a certain concentration in the glass matrix, improved the mechanical strength of the glass scaffolds, which mimic the cancellous bone. Additionally, the inclusion of hBN nanoparticles enhanced the in vitro hydroxyapatite-forming ability of bioactive glass composites. The presence of hBN nanoparticles accelerated the drug release rates of the system. It was concluded that bioactive glass/hBN composite scaffolds mimicking native bone tissue could be used for bone tissue repair and regeneration applications.

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Fayyazbakhsh, Fateme, Mehran Solati-Hashjin, M. A. Shokrgozar, S. Bonakdar, Y. Ganji, Navid Mirjordavi, S. A. Ghavimi e P. Khashayar. "Biological Evaluation of a Novel Tissue Engineering Scaffold of Layered Double Hydroxides (LDHs)". Key Engineering Materials 493-494 (ottobre 2011): 902–8. http://dx.doi.org/10.4028/www.scientific.net/kem.493-494.902.

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Bone Tissue Engineering (BTE) composed of three main parts: scaffold, cells and signaling factors. Several materials and composites are suggested as a scaffold for BTE. Biocompatibility is one of the most important property of a BTE scaffold. In this work synthesis of a novel nanocomposite including layered double hydroxides (LDH) and gelatin is carried out and its biological properties were studied. The co-precipitation (pH=11) method was used to prepare the LDH powder, using calcium nitrate, Magesium nitrate and aluminum nitrate salts as starting materials. The resulted precipitates were dried. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) analyses were used to characterize the synthesized powders. The results demonstrated the presence of nanocrystals of Ca-LDH and Mg-LDH as Hexagonal and Layered Morphology. The obtained powders were composed to gelatin via solvent casting method then freez dried. The scaffold was prepared via membrane lamination method from the resulted layers that linked together with gelatin as binder. In order to investigate the scaffold cytotoxicity MTT assay was done with a osteosarcoma cell line. No toxic response was observed in specimens. As a major result, it was demonstrated that the specimen showed a significant cellular response. Then osteosarcoma cells were cultured for 7-day and 14-day extract of powders. The composites osteoconductivity was investigate with cells alkaline phosphatase extraction. The results demonstrated that the Ca-LDH/gelatin composite scaffold has a good potential for bone tissue engineering applications and Mg-LDH specimen has a better osteconductivity.

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Virk, Ranjot Singh, Muhammad Atiq Ur Rehman, Muhammad Azeem Munawar, Dirk W. Schubert, Wolfgang H. Goldmann, Ján Dusza e Aldo R. Boccaccini. "Curcumin-Containing Orthopedic Implant Coatings Deposited on Poly-Ether-Ether-Ketone/Bioactive Glass/Hexagonal Boron Nitride Layers by Electrophoretic Deposition". Coatings 9, n. 9 (8 settembre 2019): 572. http://dx.doi.org/10.3390/coatings9090572.

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Electrophoretic deposition (EPD) was used to produce a multilayer coatings system based on chitosan/curcumin coatings on poly-ether-ether-ketone (PEEK)/bioactive glass (BG)/hexagonal boron nitride (h-BN) layers (previously deposited by EPD on 316L stainless steel) to yield bioactive and antibacterial coatings intended for orthopedic implants. Initially, PEEK/BG/h-BN coatings developed on 316L stainless steel (SS) substrates were analyzed for wear studies. Then, the EPD of chitosan/curcumin was optimized on 316L SS for suspension stability, thickness, and homogeneity of the coatings. Subsequently, the optimized EPD parameters were applied to produce chitosan/curcumin coatings on the PEEK/BG/h-BN layers. The multilayered coatings produced by EPD were characterized in terms of composition, microstructure, drug release kinetics, antibacterial activity, and in vitro bioactivity. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) confirmed the deposition of chitosan/curcumin on the multilayer coating system. The release of curcumin upon immersion of multilayer coatings in phosphate-buffered saline (PBS) was confirmed by ultraviolet/visible (UV/VIS) spectroscopic analysis. The antibacterial effect of chitosan/curcumin as the top coating was determined by turbidity tests (optical density measurements). Moreover, the multilayer coating system formed an apatite-like layer upon immersion in simulated body fluid (SBF), which is similar in composition to the hydroxyapatite component of bone, confirming the possibility of achieving close bonding between bone and the coating surface.

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Bakan, Feray, Meltem Sezen, Merve Gecgin, Yapincak Goncu e Nuran Ay. "Structural and Chemical Analysis of Hydroxyapatite (HA)-Boron Nitride (BN) Nanocomposites Sintered Under Different Atmospheric Conditions". Microscopy and Microanalysis 23, n. 5 (24 agosto 2017): 891–99. http://dx.doi.org/10.1017/s1431927617012405.

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AbstractCalcium phosphate derivatives have been widely employed in medical and dental applications for hard tissue repair, as they are the main inorganic constitution of hard tissue; such as bones and teeth. Owing to their excellent osteoconductive and bioactive properties, hydroxyapatite- (HA) based ceramics are the best candidates of this group for medical, bioscience, and dental applications. However, when replacing a bone or tooth, HA is not able to sustain similar mechanical properties. In this study, to improve the mechanical properties, nanoscale hexagonal boron nitride with different compositional percentages was added to the nano HA to form composites. The effect of compositional changes and sintering parameters on microstructural and morphological properties of the ceramic composites was comparatively investigated. Detailed chemical characterization of the composite materials was carried out using X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, and energy-dispersive X-ray spectroscopy, whereas scanning electron microscopy and atomic force microscopy investigations were employed to monitor morphological and surface features. Additional transmission electron microscopy investigations were carried out to reveal the nanostructure and crystal structure of the composites.

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Ozbek, Burak, Barkın Erdogan, Nazmi Ekren, Faik Nuzhet Oktar, Sibel Akyol, Besim Ben-Nissan, Hilal Turkoglu Sasmazel et al. "Production of the novel fibrous structure of poly(ε-caprolactone)/tri-calcium phosphate/hexagonal boron nitride composites for bone tissue engineering". Journal of the Australian Ceramic Society 54, n. 2 (19 ottobre 2017): 251–60. http://dx.doi.org/10.1007/s41779-017-0149-0.

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Sánchez-Campos, Daniel, Maria Isabel Reyes Valderrama, Susana López-Ortíz, Daniela Salado-Leza, María Eufemia Fernández-García, Demetrio Mendoza-Anaya, Eleazar Salinas-Rodríguez e Ventura Rodríguez-Lugo. "Modulated Monoclinic Hydroxyapatite: The Effect of pH in the Microwave Assisted Method". Minerals 11, n. 3 (17 marzo 2021): 314. http://dx.doi.org/10.3390/min11030314.

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Hydroxyapatite (HAp) is a natural hard tissue constituent widely used for bone and tooth replacement engineering. In the present work, synthetic HAp was obtained from calcium nitrate tetrahydrate (Ca(NO3)2·4H2O) and ammonium phosphate dibasic (NH4)2HPO4 following an optimized microwave assisted hydrothermal method. The effect of pH was evaluated by the addition of ammonium hydroxide (NH4OH). Hence, different characterization techniques were used to determine its influence on the resulted HAp powders’ size, shape, and crystallinity. By Transmission Electron Microscopy (TEM), it was observed that the reaction pH environment modifies the morphology of HAp, and a shape evolution, from sub-hedral particles at pH = 7 to rod-like nanosized HAp at pH = 10, was confirmed. Using the X-ray Diffraction (XRD) technique, the characteristic diffraction peaks of the monoclinic phase were identified. Even if the performed Rietveld analysis indicated the presence of both phases (hexagonal and monoclinic), monoclinic HAp prevails in 95% with an average crystallite size of about 23 nm. The infrared spectra (FTIR) showed absorption bands at 3468 cm−1 and 630 cm−1 associated with OH− of hydroxyapatite, and bands at 584 cm−1, 960 cm−1, and 1090 cm−1 that correspond to the PO43− and CO32− characteristic groups. In summary, this work contributes to obtaining nanosized rod-like monoclinic HAp by a simple and soft method that has not been previously reported.

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SAMUR, Enes Arda, e Tolga DEMİRCAN. "Investigation of the effects of using hexagonal boron nitride-water nanofluid on thermal performance in solar collectors". Journal of Boron, 31 luglio 2022. http://dx.doi.org/10.30728/boron.1113557.

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Bu çalışmada parabolik güneş kolektöründe kullanılan toplayıcı bir borunun içine dikdörtgen spiral bir kanatçık eklenilmesi ve nanoakışkan kullanımının ısıl performansa olan etkileri sayısal olarak incelenmiştir. Kanatçığın boru uzunluğu boyunca spiral sarım sayısı değiştirilerek dört adet model geometri oluşturulmuştur. Toplayıcı borunun içinden Hegzagonal Bor Nitrür-Su (hBN-su) nanoakışkanının geçtiği kabul edilmiştir. Nano akışkanın hacimsel karışım oranları %0 ile %4 aralığında değiştirilmiştir. Akış laminer bir akıştır ve Reynolds sayısı sabit 1500 değerinde alınmıştır. Farklı parametreler için Hesaplamalı akışkanlar Dinamiği yardımı ile analizler yapılmıştır. Çalışmanın sonucunda, nanoakışkan içindeki hBN partikülünün hacimsel karışım oranı artırıldıkça ısı transferinin arttığı gözlemlenmiştir. Ayrıca toplayıcı boru içerisine eklenen kanatçığın sarım sayısının artırılması da ısı transferini artırmıştır. Toplayıcı boruya kanatçık eklenmesi ve hBN nanoakışkanının kullanımı ile, kanatçıksız ve içinden sadece su akan bir toplayıcı boruya göre, ısı taşınım katsayısının değeri yaklaşık %284 Nusselt sayısının değeri ise yaklaşık %256 artış göstermiştir.

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Yang, Gongxian, Bin Zou, Xinfeng Wang, Lei Li, Qinghua Chen, Xingguo Zhou, Qingguo Lai e Chuanzhen Huang. "Stereolithography Printing and Mechanical Properties of Polyethylene Glycol Diacrylate/Hexagonal Boron Nitride Ceramic Composites". Advanced Engineering Materials, 25 ottobre 2024. http://dx.doi.org/10.1002/adem.202401572.

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To enhance the mechanical properties of bioceramic composite bone scaffolds, a composite paste of polyethylene glycol diacrylate (PEGDA) and hexagonal boron nitride (h‐BN) with a solid content of up to 42 wt% was developed in this study. The part was produced using stereolithography (SLA). The SLA printing parameters and material ratios of the paste were optimized through a homogeneous design and mechanical property tests. The results indicate that the single‐line curing width of the PEGDA/h‐BN paste in the XY plane ranged from 172 to 209 μm, while the curing depth of a single layer along the Z‐axis ranged from 99 to 154 μm. Laser power was identified as the primary factor influencing both the width and depth of curing. The compressive strength of the printed sample of PEGDA/h‐BN ceramic composite paste was measured at 222.4 ± 5.6 MPa, which is 61 times greater than the compressive strength of a pure PEGDA structure and comparable to that of cortical bone (100‐230 MPa). Finally, the superior biocompatibility of PEGDA/h‐BN ceramics was confirmed through cytotoxicity experiments. Consequently, PEGDA/h‐BN ceramic composites meet the mechanical properties and biocompatibility requirements necessary for bone tissue applications, indicating promising potential in the field of bone tissue engineering.

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Ensoylu, Mertcan, Aylin M. Deliormanlı e Harika Atmaca. "Hexagonal Boron Nitride/PCL/PLG Coatings on Borate Bioactive Glass Scaffolds for Bone Regeneration". Journal of Inorganic and Organometallic Polymers and Materials, 9 marzo 2022. http://dx.doi.org/10.1007/s10904-022-02246-8.

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Meriç, Neslihan, Fatih Kar e Ezgi Kar. "Evaluation of the Proliferative Effects of Hexagonal Boron Nitride Nanoparticles on Leukemia Cells and Leukemia Stem Cells". OSMANGAZİ JOURNAL OF MEDICINE 47, n. 1 (18 novembre 2024). http://dx.doi.org/10.20515/otd.1550401.

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Leukemia is a malignant disease that affects the bone marrow, lymphatic system, spleen, and blood-forming organs, leading to an excessive proliferation of white blood cells. Current cancer treatments are often limited by drug resistance, highlighting the need for novel therapeutic strategies. Nanoparticles, including boron nitride (BN) nanomaterials, have shown promise in enhancing drug delivery and therapeutic efficacy due to their excellent physical and chemical properties. This study aimed to evaluate the cytotoxic effects of hexagonal boron nitride nanoparticles (hBN NPs) on leukemia cells and leukemia stem cells to explore their potential use in leukemia treatment.: hBN NPs were synthesized and characterized using X-ray powder diffraction (XRD), Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM). Leukemia cell lines (HL-60 and CCRF-CEM) and CD34+ leukemia stem cells were treated with various hBN NPs. Cell viability was assessed using MTS assays, and flow cytometry was employed to analyze the expression of leukemia surface markers. The study found that hBN NPs did not exhibit significant anticancer properties; instead, they promoted cell proliferation in leukemia cells and stem cells. The CCRF-CEM CD34+ cells showed resistance to hBN NPs treatment, which reduced the treatment's therapeutic efficacy. The lack of cytotoxicity toward healthy cells suggests potential selectivity, yet the proliferative effects on leukemia cells indicate that hBN NPs may not be suitable for leukemia treatment. hBN NPs lack therapeutic potential for leukemia due to their proliferative effects on leukemia cells. Future studies should focus on developing combination therapies and exploring hBN NPs' impact on other cell lines to identify potential synergistic strategies that could overcome resistance mechanisms in leukemia and other cancers.

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Sundarabharathi, Lakshmanaperumal, Deepalekshmi Ponnamma, Hemalatha Parangusan, Mahendran Chinnaswamy e Mariam Al Ali Al-Maadeed. "Effect of anions on the structural, morphological and dielectric properties of hydrothermally synthesized hydroxyapatite nanoparticles". SN Applied Sciences 2, n. 1 (16 dicembre 2019). http://dx.doi.org/10.1007/s42452-019-1807-3.

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Abstract Synthetic nano hydroxyapatites (HA) have been considered as potential biomaterials for bone tissue engineering applications because of its excellent biological properties. The present work deals with the synthesis of HA nanoparticles from different anion source materials via autoclave assisted hydrothermal method. All the prepared HA nanoparticles were characterized by X-ray diffraction (XRD), Fourier transformation infrared spectra, field emission scanning electron microscopy, energy dispersive spectra and high resolution transmission electron microscopy. The XRD patterns reveal the pure and hexagonal phase structure with smaller crystallite size for HA obtained from various calcium salt precursors. HA particles prepared from nitrate precursors show spherical morphology with 32 nm grain size whereas those derived from the acetate, chloride and egg shell precursors respectively show needle-like, irregular and oval morphology. The effect of different anions on the dielectric properties and alternating conductivity of HA is investigated, as a polarized surface can trigger biological reactions. For the particles obtained from nitrate, acetate, chloride and egg shell precursors respectively give dielectric constant (εʹ) values of 9.96, 13.22, 9.92 and 10.86 at 5 MHz. The εʹ and dielectric loss (εʹʹ) values for the HA nanoparticles decrease with increase in the applied frequency as well. The alternating current conductivity values confirm that the as-synthesized HA samples exhibit insulating behavior. In short this article provides the various applicability of HA particles in optoelectronics and drug delivery. Graphic abstract

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Articoli di riviste sul tema "Nitrure de Bore hexagonale"

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