Artigos de revistas: "Microscope Ionique"

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Fragu, Philippe, Sylvain Halpern, Colette Briancon e Montesquieu Félicité Briancon. "Caracterisation fonctionnelle des tissus thyroidiens humains a l'aide du microscope ionique analytique (MIA)". Biology of the Cell 63, S1 (1988): 2–2. http://dx.doi.org/10.1016/0248-4900(88)90131-1.

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Chassard-Bouchaud, C., Ch Galle e E. Lopez-Rabereau. "Bioaccumulation d'aluminium chez la truite Salmo truffa fario soumise au retombées des pluies acides : étude structurale, ultrastructurale et microanalytique". Revue des sciences de l'eau 5, n.º 1 (12 de abril de 2005): 37–54. http://dx.doi.org/10.7202/705119ar.

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Des études microanalytiques ont été menées sur des truites Salmo trutta fario, âgées de deux ans, récoltées dans une rivière des Vosges soumise aux retombées des pluies acides et sur des truites témoins récoltées dans une rivière d'Auvergne, non soumise aux pluies acides. La rivière des Vosges est caractérisée par un pH de 5,42 et par une concentration en aluminium de 200 µg/L-1. Notre but étant de déterminer les tissus, cellules et organites cibles de bioaccumulation éventuelle de l'aluminium, nous avons analysé rein, foie, branchie et tractus digestif. Deux méthodes microanalytiques ont été utilisées pour localiser l'aluminium à l'échelle cellulaire et subcellulaire et connaître les éléments avec lesquels il peut être associé; ce sont la spectrométrie de masse par émission ionique secondaire (microscope ionique associé à un système informatisé de traitement d'images) et la spectrométrie des rayons X (microsonde électronique de Castaing associée à un microscope électronique à transmission). La microanalyse des rein, foie, branchie et tractus digestif montre l'existence de deux processus conduisant à la bioaccumulation de l'aluminium. Le premier, classiquement connu pour d'autres métaux, met en évidence une insolubilisation de l'aluminium sous forme de phosphate, dans des organites limités par une membrane : les lysosomes et les granules pigmentaires des mélanocytes. Le second, démontre la formation de volumineux dépots extra-cellulaires, atteignant 100 µm de long et entraînant la destruction du tissu. Aucune bioaccumulation significative d'aluminium n'a été observée chez des truites témoins, récoltées dans le centre de la France, où l'eau à pH 7.9 est dépourvue d'aluminium.

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Briand, P. "Microscopes à conductance ionique et électrophysiologie". médecine/sciences 5, n.º 5 (1989): 345. http://dx.doi.org/10.4267/10608/3978.

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Galle, P. "Cartographies moléculaires ultrastructurales par microscopie ionique". médecine/sciences 7, n.º 9 (1991): 944. http://dx.doi.org/10.4267/10608/4483.

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Galle, P. "La microscopie ionique analytique des tissus biologiques". Annales de Physique 10, n.º 4 (1985): 287–305. http://dx.doi.org/10.1051/anphys:01985001004028700.

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Zhang, Lili, Par Pierre Galle, Françoise Escaig e Fabienne Dantin. "Distribution subcellulaire de molécules pharmacologiques par microscopie ionique". Biofutur 1998, n.º 175 (fevereiro de 1998): A7—A8. http://dx.doi.org/10.1016/s0294-3506(98)90084-9.

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Allain Croisy, Par, e Jean-Luc Guerquin-Kern. "La microscopie ionique de seconde génération: principes et perspectives d'application biologique". Biofutur 1998, n.º 175 (fevereiro de 1998): A2—A7. http://dx.doi.org/10.1016/s0294-3506(98)90083-7.

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Mony, M. C., e Par E. Larras-Regard. "Application de la microscopie ionique à l'étude des cibles subcellulaires d'une molécule thérapeutique séléniée". Biofutur 1998, n.º 175 (fevereiro de 1998): A9—A11. http://dx.doi.org/10.1016/s0294-3506(98)90085-0.

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Elbast, Mouhamad, Ting-Di Wu, Françoise Guiraud-Vitaux, Anne Petiet, Elif Hindié, Christophe Champion, Alain Croisy, Jean-Luc Guerquin-Kern e Nicole Colas-Linhart. "Cinétique intracolloïdale de l'iode dans la thyroïde de rat nouveau-né. Imagerie directe par microscopie ionique analytique". Comptes Rendus Biologies 331, n.º 1 (janeiro de 2008): 13–22. http://dx.doi.org/10.1016/j.crvi.2007.10.005.

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Pimneva, L. A., e A. A. Zagorskaya. "Complex oxides of copper and manganese as the base material for catalytic suppression of waste gases". E3S Web of Conferences 220 (2020): 01094. http://dx.doi.org/10.1051/e3sconf/202022001094.

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The composite material “ionite-sorbed ions” was obtained by ion exchange technology. The conditions for obtaining the composite material “ionite-sorbed ions” are studied. In the thermolysis of cationite with sorbed ions, the synthesis of complex oxide is carried out between ions located at atomic distances from each other. This facilitates and accelerates the formation of complex oxide. Thermolysis of carboxyl cationite KB-4P-2 with sorbed copper and manganese ions was performed at temperatures from 250-950°C . Control of the thermolysis mechanism of the composite material “ionite-sorbed ions” was carried out using thermograms. According to the scanning electron microscopy data, the obtained powder of complex copper and manganese oxide has a good crystallite structure. Data x-ray diffraction analysis confirmed the crystallization of a complex oxide of copper and manganese in orthorhombic crystal structure. A method for the synthesis of complex copper and manganese oxide powder based on the thermolysis process of the composite material “ionite-sorbed ions”, which has catalytic properties, has been developed.

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Morgan, S. W., e M. R. Phillips. "Time Dependent Study of the Positive ion Current in the Environmental Scanning Electron Microscope (ESEM)". Microscopy and Microanalysis 7, S2 (agosto de 2001): 788–89. http://dx.doi.org/10.1017/s1431927600030014.

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The Environmental Scanning Electron Microscope (ESEM) is capable of image generation in a gaseous environment at sample chamber pressures of up to 20 torr. in an ESEM, low energy secondary electrons emitted from a sample surface, by virtue of the primary electron beam, are accelerated towards the positively biased metallic ring (typically +30 to +550V) Gaseous Secondary Electron Detector (GSED). As these electrons accelerate towards the ring they undergo ionizing collisions with gas molecules producing positive ions and additional electrons known as environmental secondary electrons. The environmental electrons further ionize the gas on their way to the ring producing a cascade amplification of the original signal. The amplified signal induced in the ring is used to form an image. The electric field generated between the GSED ring and the grounded stage causes the positive ions produced in the cascade to drift towards the sample, effectively neutralizing negative charge build up on the surface of a non-conducting sample.

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Pareige, P., M. Akamatsu e P. Auger. "Démixtion de la solution solide d’alliages FeCu sollicitée par revenu thermique, irradiation aux électrons et irradiation aux neutrons : étude par microscopie ionique et sonde atomique." Revue de Métallurgie 90, n.º 9 (setembro de 1993): 1148. http://dx.doi.org/10.1051/metal/199390091148.

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Gupta, A. K., Maurya S D, R. C. Dhakar e R. D. Singh. "pH-Sensitive Interpenetrating Hydrogel for Eradication of Helicobacter pylori". International Journal of Pharmaceutical Sciences and Nanotechnology 3, n.º 2 (31 de agosto de 2010): 924–32. http://dx.doi.org/10.37285/ijpsn.2010.3.2.5.

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The interpenetrating hydrogels of clarithromycin were prepared by chemical crosslinking process using chitosan, poly (vinylpyrrolidone) and poly (acrylic acid) polymers and glutaraldehyde and N,N’-methylenebisacrylamide as crosslinking agents. The hydrogels were evaluated for FTIR analysis, differential scanning calorimetry (DSC), drug entrapment efficiency, scanning electron microscopy (SEM), swelling study, in-vitro drug release and mucoadhesive study. The formulation containing higher amount of chitosan showed greater swelling and drug release because of higher amount of NH2 as pendant group, which ionize at lower PH values. Finally, it was concluded that by appropriate modification of polymer ratio the extent of swelling and rate of drug release can be modulated. The result showed that IPN hydrogels prepared release the drug at lower PH value (PH 2.0) or in stomach thus maintaining antibiotic concentration in stomach for prolonged period of time.

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Griffin, Brendan J. "A New Mechanism for the Imaging of Crystal Structure in Non-Conductive Materials: An Application of Charge-Induced Contrast in the Environmental Scanning Electron Microscope (ESEM)". Microscopy and Microanalysis 3, S2 (agosto de 1997): 1197–98. http://dx.doi.org/10.1017/s1431927600012873.

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The mechanism of the contrast in ‘environmental’ or ‘gaseous’ secondary electron images in the environmental scanning electron microscope is at best poorly understood. The original theory suggested a simple gas amplification model in which emitted secondary electrons ionise the chamber gas, leading to signal amplification and finally measurement at a biased detector. This theory is being advanced but little attention has as yet been paid to the factors which influence the actual secondary emission, although unusual contrast effects have been noted in one case. The conven-tional view is that the positive ion product of the gas-electron interaction results in charge neu-tralisation at the sample surface.The implantation and trapping of charge in non-conductive materials was recently described, in reference to electron range measurements. This work demonstrated that trapped charge influ-enced the secondary electron yield, with enhanced secondary electron emission above the region of trapped charge. The consequence is that the distribution of the trapped charge is seen as a bright circle on the surface of the specimen, centred on the point of beam exposure (Fig.l).

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Peng, Rui, Yongcheng Lu, Qin Zhang, Yuanming Lai, Guoliang Yu, Xiaohui Wu, Yuanxun Li, Hua Su e Huaiwu Zhang. "Amelioration of sintering and multi-frequency dielectric properties of Mg3B2O6: A mechanism study of nickel substitution using DFT calculation". Journal of Advanced Ceramics 10, n.º 6 (30 de setembro de 2021): 1398–407. http://dx.doi.org/10.1007/s40145-021-0515-9.

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AbstractWith the support of density functional theory (DFT) calculation, the amelioration of sintering and dielectric properties of the Mg3B2O6 (MBO) ceramic was realized through the substitution of magnesium with nickel. The TE-mode cylindrical cavity method was used to measure the dielectric properties at different frequencies. The thermo-mechanical analysis and simultaneous thermal analysis were used to characterize the chemical and mechanical properties. The phase composition was determined through the X-ray diffraction (XRD) and Raman spectrum. The microstructure was investigated using the scanning electron microscopy (SEM). Magnesium substitution with nickel (4 mol%) could ionize the B-O bond of BO3, modify the vibration mode, improve the order degree, densify the microstructure, decrease the intrinsic densification temperature, and ameliorate the dielectric properties of the MBO ceramics. The maximum values were achieved for the ceramics with 4 mol% nickel and sintered at 1175 °C, that is, 97.2% for relative density, 72,600 GHz (10 GHz), 75,600 GHz (11.4 GHz), and 92,200 GHz (15 GHz) for Q × f, 7.1 (10 GHz), 7.01 (11.4 GHz), and 6.91 (15 GHz) for εr, and −56.3 ppm/°C for τf.

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Aljeboree, Aseel M., Nadher D. Radia, Zeina M. Kadam, Yahya A. Faleh, Usama S. Altimari, Ashour H. Dawood e Ayad F. Alkaim. "Study on Control-release and Synchronized of Metformin Hydrochloride Drug from Hydrophilic Polymers AgNP/SCC-g-poly (AAc-AAm)". INTERNATIONAL JOURNAL OF DRUG DELIVERY TECHNOLOGY 13, n.º 02 (25 de junho de 2022): 708–12. http://dx.doi.org/10.25258/ijddt.13.2.38.

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In this study, based on the free radical polymerization, a high-efficiency sodium carboxymethyl cellulose-grafted-Poly (acryl acid-acrylic amide) (SCC-g-Poly (AAc-AAm) hydrogel was prepared using initiators for the generation of free radicals (KPs) and a cross-linking agent, N,N’-Methylene-bis-acrylamide (MBA) as well as loading silver nanoparticles onto SCC-g-poly (AAc-AAm) hydrogel cross-linked by silver nitrate was added at the concentration (1000 mg/L) for about one day to load silver ions on the surface. utilized this AgNP/SCC-g-poly (AAc-AAm) hydrogel to drug release of metformin hydrochloride (MH) was studied at different acid mediums (pH = 7.4 and 1.2) and temperatures of 37℃. This study then studied the ability of the surface to release silver controlled. Field emission scanning electron microscopy (FESEM), Fourier-transform infrared (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), atomic force microscopy (AFM) as well as Brunauer–Emmett–Teller (BET), were among the techniques used to examine the prepared surface’s properties. The highest reported drug release rates occurred at (pH = 7.4) when the rate of drug release was 97.19% after 500 minutes. This is caused by the hydrogel containing COOH, C=O, and OH groups that ionize in the neutral medium (pH = 7.4), forming negative ions, which electrostatically repel each other with the unshared electron pair of the NH group. On the contrary to in an acidic medium (pH = 1.2), the hydrophilic groups included in the hydrogel composition are saturated, making them bond with hydrogen bonds with each other and the percentage of swelling of hydrogel is very small. Two different bacteria species (Gram-negative and Gram-positive bacteria) were used to study the AgNP/SCC-g-poly (AAc-AAm) hydrogel and the ability of the surface to inhibit the two types of bacteria.

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Camus, Patrick P. "Field-assisted ionization theory for microscopists". Proceedings, annual meeting, Electron Microscopy Society of America 52 (1994): 820–21. http://dx.doi.org/10.1017/s0424820100171833.

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The theory of field ion emission is the study of electron tunneling probability enhanced by the application of a high electric field. At subnanometer distances and kilovolt potentials, the probability of tunneling of electrons increases markedly. Field ionization of gas atoms produce atomic resolution images of the surface of the specimen, while field evaporation of surface atoms sections the specimen. Details of emission theory may be found in monographs.Field ionization (FI) is the phenomena whereby an electric field assists in the ionization of gas atoms via tunneling. The tunneling probability is a maximum at a critical distance above the surface,xc, Fig. 1. Energy is required to ionize the gas atom at xc, I, but at a value reduced by the appliedelectric field, xcFe, while energy is recovered by placing the electron in the specimen, φ. The highest ionization probability occurs for those regions on the specimen that have the highest local electric field. Those atoms which protrude from the average surfacehave the smallest radius of curvature, the highest field and therefore produce the highest ionizationprobability and brightest spots on the imaging screen, Fig. 2. This technique is called field ion microscopy (FIM).

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Cherpi, M., A. Delage, T. Paul e M. Renard. "Nociception in the Skin: nociceptors are no longer the only actors". Douleur et Analgésie 32, n.º 4 (dezembro de 2019): 217–20. http://dx.doi.org/10.3166/dea-2020-0081.

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Les nocicepteurs à terminaisons libres ont longtemps été considérés comme les seuls senseurs nociceptifs dans la peau. Abdo et al. réévaluent le rôle des cellules de Schwann (CSs), cellules gliales de soutien du système nerveux périphérique, dans la perception de la douleur chez la souris. Après observation de la morphologie et de la localisation des CSs et des fibres nociceptives dans la peau, les chercheurs s’intéressent à leur relation fonctionnelle. Ils génèrent des souris exprimant des canaux ioniques photosensibles à la surface des CSs. Cela leur permet de les stimuler spécifiquement (par optogénétique) tout en mesurant la réponse électrique du nerf palmaire. En combinant l’excitation ou l’inhibition des CSs avec des tests comportementaux, ils mesurent la capacité des CSs à sensibiliser les souris à la douleur thermique et mécanique. Enfin, des CSs sont isolées pour évaluer leur capacité à répondre à un stimulus mécanique. Les observations par microscopie électronique et à fluorescence révèlent que les nocicepteurs se trouvent entourés par le cytoplasme des CSs dans le derme et accolés à ces dernières dans l’épiderme. Ce complexe glioneural se ramifie au niveau subépidermal. Les chercheurs décident ainsi d’appeler ces cellules gliales « cellules de Schwann nociceptives » (CSn). Leur stimulation par optogénétique révèle une augmentation de l’activité électrique des fibres nociceptives, des comportements « de douleur » chez la souris, et augmente la sensibilité des souris aux stimuli douloureux mécaniques et thermiques. L’inhibition via optogénétique des CSn diminue leur sensibilité aux stimuli mécaniques mais ne modifie pas leur sensibilité aux stimuli thermiques. L’enregistrement unicellulaire des CSn révèle qu’elles sont hautement sensibles aux stimuli mécaniques. Les auteurs de cette étude ont découvert un nouveau type de cellule de Schwann nociceptive jouant un rôle important dans la genèse et modulation de la nociception cutanée.

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Yu, Da Wei, Jin Bing Zhang e Gui Mei Shi. "Prepared and Magnetic Properties of B₄C/C Coated Co Nanocapsules". Materials Science Forum 694 (julho de 2011): 328–31. http://dx.doi.org/10.4028/www.scientific.net/msf.694.328.

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B4C/C coated Co nanocapsules were prepared by arc-discharging a Co-B amorphous alloy. The structure, morphology and surface composition as well as magnetic properties were investigated by X-Ray diffraction, High Resolution Transmission Electron Microscopy and XPS photoelectron spectrum as well as Vibrating Sample Magnetometer, respectively. The results show the as-prepared nanoparticles form in a core¬¬¬-shell structure with the size of nanoparticles in range of 20-100nm, the thickness of the shell is about 3-10nm. The core is Co grains, while the shell is B4C/C compound. That B4C coated Co nanoparticles form in a core¬¬¬-shell structure ascribed to Co as catalysts accelerating reaction between B with C ionize in the arc-discharge course. This structure can prevent Co nanoparticles from oxidation and agglomeration. A saturation magnetization of Ms=75.6 Am2/kg and a coercive force of Hc=20.1 kA/m are achieved for as-prepared nanocapsules by VSM. For as–prepared nanocapsules, the saturation magnetization is reduced and coercive force of is enhanced while Comparing with Co block. The increase coercive force for as-prepared nanoparticles can be mainly ascribed to size of particles diminished and the domain-wall depinned in the multi-domain particles.

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Fitriawan, Helmy. "Simulation and Modeling Time Response of Double Carrier Avalanche Photodiodes". Journal of Engineering and Scientific Research 2, n.º 2 (28 de dezembro de 2020): 102–6. http://dx.doi.org/10.23960/jesr.v2i2.45.

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Avalanche photodiodes (APDs) is a particularly sensitive semiconductor device that employs the photoelectric effect to convert light into electricity. APDs can be used in some typical applications, i.e. imaging, optical fiber communications, range finding, laser scanners and laser microscopy. In APDs, avalanche multiplication occurred due to impact ionization when the devices operating at high electric fields. Unfortunately, avalanche multiplication decreases the time response of APDs. The time response of an APD can be characterized by its current response which is represented by the mean current as a function of time. This paper discusses a method to estimate the time response of double-carrier multiplication avalanche photodiodes (APDs). The model, called The Random Path Length (RPL), generates random path length for a carrier to impact ionize and takes account of dead space distance into the calculation. Dead space distance is the minimum distance to travel by a carrier to gain the adequate energy to start first ionization. The RPL is applied into an ideal structure which is assumed has a dimensionless multiplication length, w = 1.0, with electrons and holes moving in constant speeds, ve = vh = v, for various dead spaces distances, d*. In this research, a computer code is generated to compute the mean impulse response, i(t), and the standard deviation, s(t), of APDs all as a function of time.

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Kranz, Michael, Mark Allen e Tracy Hudson. "In-Situ Wafer-Level Polarization of Electret Films in MEMS Acoustic Sensor Arrays". Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2011, DPC (1 de janeiro de 2011): 001732–60. http://dx.doi.org/10.4071/2011dpc-wp24.

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MEMS-based electret and polymer piezoelectric transduction techniques have been reported for both acoustic sensors and energy harvesters. Common techniques employed in MEMS polymer polarization include corona discharge and backlighted thyratron. This paper reports a method for post-fabrication in-situ polarization of polymer films embedded within the MEMS device itself. The method utilizes microplasma discharges with self-aligned charging grids integrated within the device to charge fluoropolymer films in a fashion similar to the common corona discharge technique. This in-situ approach enables the integration of uncharged polymer films into MEMS and subsequent post-fabrication and post-packaging polarization, simultaneously enabling the formation of buried or encapsulated electrets as well as eliminating the need to restrict fabrication and packaging processes that might otherwise discharge pre-charged materials. CYTOP, a thermoplastic fluoropolymer encapsulant for electronics, is used as a polymer electret in the current process because it can be spin-cast, has a high resistivity, and is easily etched in oxygen plasma. A microscale charging grid structure is then fabricated and suspended a short distance above the polymer film. After fabrication of the charging grid, standard microfabrication steps are performed to build a single-chip array of MEMS capacitive acoustic sensors designed to capture and analyze waveforms from impacts. After completing the entire fabrication and packaging flow, the polarization process is performed. When energized by a high voltage, the sharp metal edges of the charging grid lead to high dielectric fields that ionize the air in the gap and force electric charge onto the polymer surface. Final sensor arrays have been demonstrated and applied in the classification of acoustic stress pulses generated during impacts of various materials.

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ANY- GRAH, Sandrine Armelle AKA, Nakognon Awa TUO-KOUASSI, Koffi Victor Kouakou, Kakwokpo Clémence N’GUESSAN-GNAMAN, Rosine Désirée N’KUITCHOU-CHOUGUO, Gnahoré José Arthur LIA, Alain N’GUESSAN, Ismael DALLY e Armand KOFFI. "Etude comparative de microparticules à base de pectine de Mangifera indica L. (Anacardiaceae) versus la pectine synthétique". Journal Africain de Technologie Pharmaceutique et Biopharmacie (JATPB) 2, n.º 3 (20 de dezembro de 2023). http://dx.doi.org/10.57220/jatpb.v2i3.126.

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Introduction : La pectine est un polysaccharide retrouvé dans la paroi de nombreuses cellules végétales, notamment dans les fruits mûrs. Elle possède d’excellentes propriétés gélifiantes qui en font un ingrédient particulier dans l’industrie alimentaire et pharmaceutique. Elle est obtenue également par synthèse, donnant lieu à la pectine synthétique. Dès lors, les propriétés de ces deux sources de pectine seraient-elles identiques ? L’objectif de notre travail était de comparer des formulations de microparticules d’acide salicylique à partir de pectine naturelle de Mangifera indica L. et de pectine synthétique. Méthodes : La gélification ionique a été utilisée pour la fabrication des microparticules. Pour la préparation 3% de pectine naturelle contre 2% de pectine synthétique ont été utilisé dans du tampon citrate à pH 5 avec du chlorure de calcium (CaCl2) à 0,2%. La solution de réticulation était du CaCl2 à 10%. Les microparticules obtenues ont été caractérisées sur le plan macroscopique par la vérification de la couleur et de la forme. La taille des particules a été déterminée au microscope optique permettant de calculer les déciles. Enfin les différents taux d’encapsulation ainsi que les rendements d’encapsulation ont été déterminés. Résultats : Les microparticules obtenues avec la pectine naturelle étaient de couleur brune et de forme aplaties, celles avec la pectine synthétique étaient de couleur blanche plus ou moins arrondies. La pectine naturelle donnait des particules de taille variant de 87 à 190 mm avec une moyenne de 137,70 mm et un rapport interdecile de 1,66. Quant à la pectine synthétique, les tailles des particules étaient comprises entre 58 et 116 mm avec une moyenne de 85,19 mm et un rapport interdecile de 1,55. Le taux d’encapsulation avec la pectine naturelle de Mangifera indica L. était de 6,08% avec un rendement d’encapsulation de 78,5%. En ce qui concerne la pectine synthétique, elle a donné un taux d’encapsulation de 17,72% et un rendement d’encapsulation de 88%. Conclusion : Des microparticules ont pu être formulées avec la pectine naturelle de Mangifera indica L. Cependant, la pectine synthétique a donné de meilleurs résultats de formulation et a pu encapsuler plus de principe actif par rapport à la pectine naturelle.

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BLAVETTE, Didier, e Alain MENAND. "Microscopie ionique à effet de champ et sonde atomique". Techniques d'analyse, julho de 1989. http://dx.doi.org/10.51257/a-v1-p900.

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Davoigneau, Jean, Nathalie Vidal e Anne-Sophie Rozay. "De la découverte à la protection au titre des monuments historiques : la microscopie électronique et ionique". Histoire de la recherche contemporaine, Tome XII n°1 (16 de fevereiro de 2023). http://dx.doi.org/10.4000/hrc.9457.

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Elwakil, Bassma H., Ahmed M. Eldrieny, Awatif Rashed Z. Almotairy e Mostafa El-Khatib. "Potent biological activity of newly fabricated silver nanoparticles coated by a carbon shell synthesized by electrical arc". Scientific Reports 14, n.º 1 (4 de março de 2024). http://dx.doi.org/10.1038/s41598-024-54648-y.

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AbstractHighly effective AgNPs@C was efficiently synthesized by electrical arc powered by single spark unit which was sufficient to ionize the dielectric media (deionized water) through applying strong electric field between the electrodes (silver and carbon). The AgNPs@C shell was characterized in terms of stability, morphology and phase structure. All characterizations showed that the prepared silver nanoparticles were spherical with average size reached 17 nm coated with carbon shell. The antibacterial effect of the synthesized nanoparticles was tested against Pseudomonas aeruginosa in comparison to Ceftazidime (commonly used antibiotic against P. aeruginosa infections). It was revealed that AgNPs@C shell has superior activity with inhibition zone diameter reached 15 mm and minimum inhibitory concentration reached 2 µg/mL. The observed activity was further confirmed by confocal microscope which showed an increased red region, representing the dead cells, correlated with the presence of AgNPs@C. Moreover, transmission electron microscope studies implied the possible AgNPs@C antibacterial mechanism of action was the nanoparticles adherence to the bacterial membrane causing cell lysis. The molecular studies against fimH (virulence adhesion gene), rmpA (mucoid factor encoding gene), and mrkA (biofilm forming gene) proved the inhibition of their genetic expression. The cytotoxic effect of the synthesized AgNPs@C showed CC50 reached 235.5 μg/mL against normal lung cells (L929 cell line).

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Li, Luxian, Xuemei Li, Wei Deng, Chun Shen, Xinhai Chen, Han Sheng, Xiang Wang et al. "Sparking potential over 1200 V by a falling water droplet". Science Advances 9, n.º 46 (17 de novembro de 2023). http://dx.doi.org/10.1126/sciadv.adi2993.

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Hydrovoltaic technology has achieved notable breakthroughs in electric output via using the moving boundary of electric double layer, but the output voltage induced by droplets is saturated around 350 volts, and the underlying mechanism remains to be further clarified. Here, we show that falling water droplets can stably spark an unprecedented voltage up to 1200 volts within microseconds that they contact an electrode placed on top of an electret surface, approaching the theoretical upper limit. This sparking potential can be explained and described by a comprehensive model considering the water-electrode contact dynamics from both the macroscale droplet spreading and the microscale electric double layer formation, as well as the presence of a circuit capacitance. It is demonstrated that a droplet-induced electric spark is sufficient to directly ionize gas at atmospheric pressure and split water into hydrogen and oxygen, showing wide application potential in fields of green energy and intelligence.

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Stone, Greg, Yin Shi, Matthew Jerry, Vladimir Stoica, Hanjong Paik, Zhonghou Cai, Darrell G. Schlom et al. "In‐Operando Spatiotemporal Imaging of Coupled Film‐Substrate Elastodynamics During an Insulator‐to‐Metal Transition". Advanced Materials, 5 de março de 2024. http://dx.doi.org/10.1002/adma.202312673.

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AbstractThe drive towards non‐von Neumann device architectures has led to an intense focus on insulator‐to‐metal (IMT) and the converse (MIT) transitions. Studies of electric field‐driven IMT in the prototypical VO2 thin‐film channel devices are largely focused on the electrical and elastic responses of the films, but the response of the corresponding TiO2 substrate is often overlooked since it is nominally expected to be electrically passive and elastically rigid. Here, in‐operando spatiotemporal imaging of the coupled elastodynamics using x‐ray diffraction microscopy of a VO2 film channel device on TiO2 substrate reveals two new surprises. First, the film channel bulges during the IMT, the opposite of the expected shrinking in the film undergoing IMT. Secondly, a microns thick proximal layer in the substrate also coherently bulges accompanying the IMT in the film, which is completely unexpected. Phase‐field simulations of coupled IMT, oxygen vacancy electronic dynamics, and electronic carrier diffusion incorporating thermal and strain effects suggest that the observed elastodynamics can be explained by the known naturally occurring oxygen vacancies that rapidly ionize (and deionize) in concert with the IMT (MIT). Fast electrical‐triggering of the IMT via ionizing defects and an active “IMT‐like” substrate layer are critical aspects to consider in device applications.This article is protected by copyright. All rights reserved

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