Wyniki wyszukiwania - Biblioteka Nauki

1

Magnetic filtration/adsorption process for Snake River Plain Groundwater Treatment

100%

Cotten G. , Eldredge H. , Navratil J.

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tom Vol. 48, nr 1

17-23

EN

A magnetic filtration/adsorption process has been evaluated for development for groundwater treatment at the Idaho National Engineering and Environmental Laboratory (INEEL). The process uses inexpensive magnetite (FeOźFe2O3) in a supported mode surrounded by an external magnetic field. Prior studies have been shown to remove actinides and fission products in laboratory studies. This research has focused on supporting magnetite in an economical manner that promotes both magnetic filtration/adsorption of metal species and satisfactory water flow. The process utilizes the natural metal ion adsorptive properties of magnetite as well as the High Gradient Magnetic Separation (HGMS) effect for removing metal colloids and submicron particles. Results are presented on scoping studies for developing the process for groundwater treatment at the INEEL.

2

Temperature dependence of the FMR spectra of Fe3O4 and Fe3C nanoparticle magnetic systems in copolymer matrices

100%

Guskos N. , Typek J. , Roslaniec Z. , Narkiewicz U. , Kwiatkowska M. , Maryniak M.

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tom Vol. 23, No. 4

1055--1063

EN

A binary magnetic nanoparticle system, consisting of Fe3O4 (35 wt. %), Fe3C (29 wt. %), and C (36 wt. %) filling in a PTMO-block-PET polymer at low concentration (0.3 %), has been synthesized. X-ray and SEM analyses have been carried out. The temperature dependence of the FMR spectrum of this system has been investigated. At higher temperatures resonance from Fe3O4 nanoparticles dominates the FMR spectrum, while at lower temperatures a more intense line from Fe3C is recorded. The temperature dependence of the FMR spectrum confirms that the nanoparticles of Fe3O4 reach the ordered state faster than Fe3C nanoparticles. In both cases, the spin-glass state is observed below 50 K.

3

Density functional simulation of metal oxides: Al2O3 and Fe3O4

100%

Łodziana Z.

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tom Vol. 8, No 4

561-572

EN

The study of the metal oxides is a rapidly developing area of research. Below a theoretical method based on the density functional theory, common in studying ceramics, is briefly presented. Application of the theory to the surface and the bulk properties of alumina and magnetite are presented. Relaxation mechanism of two different surfaces of alumina and the (100) surface of Fe3O4 are shown. The mutual stability of the ? and ? phases of Al2O3 is calculated.

4

Synthesis of maghemite (γ-Fe2O3) nanoparticles by thermal-decomposition of magnetite (Fe3O4) nanoparticles

100%

Aliahmad M. , Nasari-Moghaddam M.

Materials Science Poland

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2013

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tom Vol. 31, No. 2

264--268

EN

In this research work, we prepared g-Fe2O3 nanoparticles by thermal-decomposition of Fe3O4. The Fe3O4 nanoparticles were synthesized via co-precipitation method at room temperature. This simple, soft and cheap method is suitable for preparation of iron oxide nanoparticles (g-Fe2O3; Fe3O4). The samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), vibrating sample magnetometer and differential scanning calorimeter (DSC). The XRD and FT-IR results indicated the formation of g-Fe2O3 and Fe3O4 nanoparticles. The TEM images showed that the g-Fe2O3 and Fe3O4 were spherical, and their size was 18 and 22 nm respectively. Magnetic properties have been measured by VSM at room temperature. Hysteresis loops showed that the g-Fe2O3 and Fe3O4 nanoparticles were super-paramagnetic.

5

An investigation on the optimum conditions of synthesizing a magnetite based ferrofluid as MRI contrast agent using Taguchi method

100%

Ahmadi R. , Hosseini H. R. M.

Materials Science Poland

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2013

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tom Vol. 31, No. 2

253--258

EN

In this study, some stabilized magnetite based ferrofluids were synthesized using Dextran as a stabilizing agent. In order to achieve optimum experimental conditions for synthesizing ferrofluids as MRI contrast agents, the Taguchi method was used. This approach was employed to design and minimize the number of required experiments. By using the Taguchi orthogonal (L16) array, four parameters including solution temperature and alkalinity, reaction temperature and stirring rate were selected at four predetermined levels for 16 experiments. Synthesizing processes established based on this set of experimental conditions were carried out and the obtained ferrofluids were characterized using PCS, VSM, TEM and FT-IR techniques. The obtained results were used and analyzed through the Qualitek-4 software and the proposed optimum experimental conditions were used for synthesizing the desired sample. Finally, this sample was used as a potential MRI contrast agent for imaging lymph nodes.

6

Photon attenuation properties of concretes containing magnetite and limonite ores

88%

Gur A. , Artig B. , Cakir T.

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tom Vol. 53, iss. 1

184--191

EN

In this study, gamma shielding properties of concretes containing magnetite and limonite ores at different ratios (5%, 10%, 15%, 20%, and 30%) were investigated by using a 60Co (1.25 MeV) radioactive source which was built in Thratron 1000E™ device used for radiotherapy purposes. Then, the photon transmission values (I/I0) were measured by 0.6 cm3, farmer type, PTW™ ion chamber. The dose readings (I0 and I), made by PTW™ Unidose Electrometer, were used to calculate the linear attenuation coefficient (, cm-1), the mean free path (, cm), and the mass attenuation coefficient (, cm2/g) by the Lambert equations, and the results were compared with the calculations obtained using the WinXCom computer program. The findings from this study revealed that the concretes containing magnetite and limonite ores were more effective than the ordinary concrete in the attenuation of gamma rays. It was determined that the values of the mean free path decreased with the increasing concentrations of magnetite and limonite ores while the linear attenuation coefficients for 10 concrete blocks increased with the increasing magnetite and limonite ore concentrations. A comparison of the theoretical values obtained from the WinXCom computer program and the experimental results revealed a good level of conformity.

7

Transformation mechanism of magnetite nanoparticles

88%

Khan U. S. , Amanullah , Manan A. , Khan N. , Mahmood A. , Rahim A.

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tom Vol. 33, No. 2

278--285

EN

A simple oxidation synthesis route was developed for producing magnetite nanoparticles with controlled size and morphology. Investigation of oxidation process of the produced magnetite nanoparticles (NP) was performed after synthesis under different temperatures. The phase transformation of synthetic magnetite nanoparticles into maghemite and, henceforth, to hematite nanoparticles at different temperatures under dry oxidation has been studied. The natural magnetite particles were directly transformed to hematite particles at comparatively lower temperature, thus, maghemite phase was bypassed. The phase structures, morphologies and particle sizes of the produced magnetic nanoparticles have been investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray spectrometry (EDX) and BET surface area analysis.

8

Mineralogical characteristic and beneficiation evaluation of rare earth carbonate wall rock

75%

Gao C. , Yan G. , Wang H. , Luo H. , Zhang L. , Yang H. , Xu J.

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tom Vol. 59, iss. 1

art. no. 161300

EN

In order to rationalize the development and utilization of the wall rock discarded during rare earth mining, chemical analysis, inductively coupled plasma-atomic emission spectroscopy, X-ray diffraction analysis, artificial panning, optical microscope analysis, mineral liberation analysis and energy-dispersive spectroscopy were used to study the process mineralogy of the wall rock. The results show that the main useful elements in the rare earth wall rock were iron, light rare earth elements, fluorine and niobium. Iron was mainly occurrence as magnetic iron in magnetite, rare earth elements in bastnaesite and monazite, fluorine as a independent mineral in fluorite and niobium in columbite. The main useful minerals were finely disseminated, with magnetite (48.16%), bastnaesite (49.04%), monazite (42.18%), fluorite (39.30%) and columbite (63.26%) distributed in -0.030 mm particle size. The useful minerals were evaluated separately for beneficiation based on the process mineralogical characteristics of the rare earth wall rock, and the results showed that magnetite, rare earth and fluorite resources could be effectively recovered using magnetic separation, flotation, gravity concentration and leaching enrichment methods. The sequential recovery of iron, rare earth, fluorine and niobium elements produces iron concentrate (65.40% TFe at recovery of 38.03%), rare earth concentrate (50.66% REE at recovery of 62.73%), fluorite concentrate (95.23% CaF2 at recovery of 40.34%) and niobium iron ore concentrate (1.63% Nb2O5 at recovery of 5.56%). This study provides recommendations for the rational development and utilization of rare earth wall rock and provides reasonable levels of recovery predictions.

9

Sorbent-Catalyst for Acceleration of The Iron Oxidation Process

75%

Gomelya M. , Tverdokhlib M. , Shabliy T. , Radovenchyk V. , Linyucheva O.

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tom Vol. 22, nr 3

221--230

EN

In this work, the process of water deironing by using magnetite as a catalyst to accelerate the oxidation of iron ions in an aqueous medium was investigated. It was shown that the efficiency of iron ion extraction depends on the solution concentration, sorbent dose and contact time. In all cases, the use of magnetite accelerated the process of extraction of iron by more than an order of magnitude in comparison with similar experiments on the oxidation of iron without the addition of a catalyst. At the pH values greater than 6, the use of magnetite as a catalyst contributes to the deep purification of water from iron ions.

10

Laser nanosoldering of golden and magnetite particles and its possible application in 3D printing devices and four-valued non-volatile memories

63%

Jaworski J. , Gawłowski G.

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tom Vol. 6, No. 4

43--54

EN

In recent years the 3D printing methods have been developing rapidly. This article presents researches about a new composite consisted of golden and magnetite nanoparticles which could be used for this technique. Preparation of golden nanoparticles by laser ablation and their soldering by laser green light irradiation proceeded in water environment. Magnetite was obtained on chemical way. During experiments it was tested a change of a size of nanoparticles during laser irradiation, surface plasmon resonance, zeta potential. The obtained golden - magnetite composite material was magnetic after laser irradiation. On the end there was considered the application it for 3D printing devices, water filters and fourvalued non-volatile memories.

11

Electromagnetic system for improving the adhesion of wheels to rails

51%

Osenin Y. , Antoshkina L. , Sosnov I. , Shapran E. , Chesnokov A.

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2019

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tom T. 14, z. 1

59--67

EN

The article describes the design of a system used for the improvement of the adhesion of locomotive wheels to rails; the principle of which is based on the electromagnetic feeding of the contact area with the bulk material that has magnetic properties and high hardness (iron scale Fe3O4 and magnetite FeO×Fe2O3). The experimental results of laboratory and bench tests confirming the effectiveness of the proposed system compared with the existing devices using quartz sand to improve the adhesion of wheels to rails are presented. It is concluded that the use of an electromagnetic system for improving the particle supply to the wheel/rail interface is promising.

12

Biodegradable polymeric template for magnetic composites on its base

51%

Tudorachi N. , Chiriac A. P.

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tom T. 54, nr 11-12

806-813

EN

Modified starch and sodium polyaspartate blend was used as a polymeric template for the preparation of a magnetic composites. Their structural and magnetic properties (by SEM, magnetometry, IR), as well as thermal stability and particle size distributions were characterized. The dependence between the magnetite content and magnetic susceptibility values is stressed. The study confirms the possibility to obtain magnetic composites from magnetite (Fe3O4) and the polymeric composite template based on carboxymethyl starch and sodium polyaspartate. The importance of these magnetic composites derives from the biodegradability of the template as well as the possibilities given by functional groups able to couple both magnetite and further bioactive substances.

PL

Otrzymano skrobię modyfikowaną kwasem monochlorooctowym (CMS) oraz sól sodową poli(kwasu asparaginowego) (PSI-Na), których mieszaninę (1:1) użyto w charakterze biodegradowalnej matrycy polimerowej w kompozytach magnetycznych. Wytworzono też nanocząstki magnetytu (Fe3O4) z mieszaniny FeCl3+FeCl2. Na podstawie wspomnianej matrycy i magnetytu sporządzono kompozyty magnetyczne zawierające 2,5%, 5% lub 25% Fe3O4. Metodą IR scharakteryzowano budowę otrzymanej matrycy i jej składników a także magnetycznego kompozytu (rys. 1-3, tabela 1 i 2). Zbadano strukturę wytworzonych produktów (SEM, rys. 5), ich termostabilność (TG i DTG, rys. 4, tabela 3) i podatność magnetyczną (rys. 6); określono także rozkład wymiarów cząstek biodegradowalnej matrycy, magnetytu oraz kompozytów magnetycznych o różnym udziale Fe3O4 (rys. 7). Podkreślono wzajemną zależność pomiędzy zawartością cząstek magnetytu a wartością podatności magnetycznej kompozytów. Wyniki przedstawionych badań potwierdzają możliwość uzyskania kompozytów CMS/PSI-Na/Fe3O4. Znaczenie takich materiałów wynika zarówno z biodegradowalności matrycy polimerowej, jak i ze zdolności obecnych w matrycy grup funkcyjnych do wiązania nie tylko magnetytu, ale i innych substancji bioaktywnych.

13

Electromagnetic Radiation Generated by Acoustic Excitation of Rock Samples

51%

Yavorovich L. V. , Bespalko A. A. , Fedotov P. I. , Baksht R. B.

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tom Vol. 64, no. 5

1446--1461

EN

The paper presents an experiment on acoustic excitation of electromagnetic radiation (EMR) signals in skarn, sandstone, and magnetite ore samples. For the skarn and sandstone samples, the EMR signal amplitude was observed to decrease with increasing ultimate strength. Supposedly, this effect can be explained by assuming that EMR is generated when an acoustic wave propagates through an electrical double layer. The presence of piezoelectric inclusions (e.g., quartz) in the magnetite ore enhances the analog EMR signal and its spectral components.

14

Obiekty przyrody nieożywionej wyspy Teneryfa

44%

Stanienda K. , Wasilczyk A.

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tom T. 6, z. 4

113-127

PL

W artykule zaprezentowano obiekty przyrody nieożywionej, typowe dla wyspy Teneryfa. Opisano skały występujące w obszarze Parku Narodowego Teide, w tym samego wulkanu Teide, a ponadto utwory odsłaniające się w obszarach Montana de Chinyero, Puerto de Santiago, Masca, Los Gigantes i Garachico. W obszarze Teneryfy dominują lawy, bazalty z widocznymi kryształami oliwinu, fonolity i skały maficzne. Można tu również spotkać trachity i andezyty, a na małych plażach czarny piasek wulkaniczny, zawierający pirokseny, oliwiny, skalenie oraz minerały żelaza (magnetyt).

EN

The objects of inanimate nature, typical for Tenerife Island were presented in this article. Rocks of the National Teide Park, including Teide Volcano, moreover rocks from outputs of Montana de Chinyero, Puerto de Santiago, Masca, Los Gigantes and Garachico were described there. Lavas, basalts with visible olivine Crystals, phonolites, and maphic rocks dominate in the area of Tenerife Island. Moreover it is possible to find there trachytes and andesites and on the beaches, black, volcanic sand with pyroxenes, olivines, feldspars and iron minerals (magnetite).