Ograniczanie wyników
Czasopisma help
Autorzy help
Lata help
Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 164

Liczba wyników na stronie
first rewind previous Strona / 9 next fast forward last
Wyniki wyszukiwania
Wyszukiwano:
w słowach kluczowych:  magnesium
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 9 next fast forward last
PL
Wiele pierwiastków chemicznych oraz ich związków ma szerokie zastosowanie w produktach dostępnych na rynku. Są obecne zarówno w produktach żywnościowych, preparatach leczniczych, jak i w kosmetykach. Na podstawie przeglądu literatury i danych producenta dokonano analizy ich aktywności oraz potencjalnych korzyści i zagrożeń wynikających z ich stosowania. Przeanalizowano też wpływ tych substancji na środowisko naturalne.
EN
A review, with 35 refs., of chem. elements and their comps. used in foods, drugs and cosmetics. Their activity, potential benefits and risks as well as environmental impacts were taken into consideration.
EN
In this study, high-purity tantalum metal powder was manufactured via self-propagating high-temperature synthesis. During the process, Ta2O5 and Mg were used as the raw material powder and the reducing agent, respectively, and given that combustion rate and reaction temperature are important factors that influence the success of this process, these factors were controlled by adding an excessive mass of the reducing agent (Mg) i.e., above the chemical equivalent, rather than by using a separate diluent. It was confirmed that Ta metal powder manufactured after the process was ultimately manufactured 99.98% high purity Ta metal powder with 0.5 μm particle size. Thus, it was observed that adding the reducing reagent in excess favored the manufacture of high-purity Ta powder that can be applied in capacitors.
EN
The choice of bottled waters available for sale is large. The assessment of their mineral composition was based on the results of 120 natural waters and 46 mineral waters (in relation to the hydrogeological classification of water mineralization). Significant diversity was found in terms of the basic mineral composition, and in many cases also a wealth of microcompounds (e.g. fluorides, iodine, selenium), which have a positive effect on the human health. Both the deficiency and excess of the water consumed and the amount of contained ingredients have an influence on the human health. While choosing water, it is worth considering the volume of water consumed, the age and health of the consumer, season of year, activity, type of diet, taken dietary supplements, vitamins and medicines. The information on the label is sufficient to choose the water suited to the individual needs. The waters with high mineralization and/or with large concentrations of microcompounds should be used after medical consultations to determine their use: specify the area of application and recommended drinking amount and frequency.
EN
Purpose: To find out more about the role of hydrogen gas bubbles in improving the hydrophobic nature of a layer, especially in the layers of microparticles Alumina (Al2O3) with Magnesium (Mg). Design/methodology/approach: The method used is an experimental method by first conducting the SEM-Edx test, testing the content of the elements in the waxy layer and observing the topographic shape on the surface of the taro leaves. Then prepare a mixture of Alumina micro particles with Magnesium to investigate the hydrophobicity of the taro leaves. The mixed presentations between Alumina and Magnesium are: (0, 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100%). Findings: The results of this study found three conditions of the Alumina and Magnesium mix layer when in contact with a droplet, namely: Hydrophobic conditions occur when the surface structure of the rough mixed micro layer forms micro crevices, then bubbles of hydrogen gas fill it to form trapped gases. When droplets come in contact with the surface of the mixed layer the effect of the gas being trapped is very effective at creating hydrophobic properties. While the transition conditions occur when more and more hydrogen gas bubbles along with the increasing percentage of Mg and the opposite occurs in micro particle fissures. Bubbles fill the micro-gap space fully so that the tops of the micro particles are covered by bubbles. This causes the droplet surface tension to weaken, so the droplet contact angle decreases. Furthermore, hydrophilic conditions occur when the micro gap is getting narrower as the percentage of Mg increases and the formation of hydrogen gas bubbles increases. The high level of bubble density in the micro gap closes the peaks of the micro particles, which results in the surface tension of the droplet getting weaker. In this weak surface tension condition, the hydrogen bubble can break through the droplet surface tension and change its hydrophobic nature to hydrophilic. Research limitations/implications: This research is limited to the hydrophobicity of Alumina and Magnesium materials, mainly to investigate the role of hydrogen gas in supporting the hydrophobic nature of taro leaves (Colocasia esculenta). Practical implications: The practical implication in this study is the use of hydrophobic membranes which are widely applied to filtration. Originality/value: Discovered the composition of a membrane mixture of Alumina (Al2O3) and Magnesium (Mg) to create hydrophilic and hydrophobic conditions.
EN
The magnesium alloy investment castings have greater potential for automobile and air-craft applications due to the higher strength to weight ratio of magnesium alloys and capability of the investment casting process to produce near net shape complex castings. The interfacial-mould metal reactions during investment casting of magnesium alloy inhibit successful production of quality castings. This paper presents the investigation done on the reactions at corners of AZ91 magnesium alloy cast part produced through investment casting. The stepped shape geometry of casting was selected to study the reactions at convex and concave corners of the cast part. The reacted surfaces were characterised using the SEM-EDX and XRD. The formation of oxides was observed on cast surface from characterisation. The temperature profile recorded at corners were helpful to understand the heat dissipation during the solidification of metal at corners. It was observed that the reactions occurred at the concave corner were more as compared to the convex corner of the cast part.
EN
The paper presents the results of a multivariable research regarding the evaluation of variability of selected quantitative traits in two cultivars of maize (Zea mays L.): ES Palazzo and ES Paroli after using doses of nitrogen and magnesium. The study took into account 12 traits recorded for three years (2009-2011). The statistical analysis of obtained results was conducted using multivariable methods: multivariate analysis of variance, canonical variable analysis and Mahalanobis distances. The most varied objects were A4B1C2 and A1B2C1 (in 2009), A4B1C1 and A2B2C2 (in 2010), A4B2C1 and A1B2C2 (in 2011) and A4B2C1 and A1B2C2 (for all three years). The most similar objects (with regard to the 12 traits analyzed together) were A4B2C2 and A3B2C2 (in 2009), A4B2C2 and A3B1C2 (in 2010), A2B2C2 and A2B1C2 (in 2011) and A4B2C2 and A3B2C2 (for all three years). The Mahalanobis distances between particular objects in particular years of observations were positive and statistically significantly correlated.
PL
W pracy przedstawiono wyniki badania zmienności wybranych cech ilościowych dwóch odmian kukurydzy (Zea mays L.): ES Palazzo i ES Paroli po zastosowaniu różnych dawek azotu i magnezu stosując wielowymiarowe metody statystyczne. W badaniach wzięto pod uwagę 12 cech ilościowych obserwowanych w doświadczeniu trzyletnim przeprowadzonym w latach 2009-2011. Analiza statystyczna uzyskanych wyników została przeprowadzona z użyciem metod wielowymiarowych: wielozmiennej analizy wariancji, analizy zmiennych kanonicznych i odległości Mahalanobisa. Najbardziej zróżnicowanymi obiektami były A4B1C2 i A1B2C1 (w 2009), A4B1C1 i A2B2C2 (w 2010), A4B2C1 i A1B2C2 (w 2011) oraz A4B2C1 i A1B2C2 (dla wszystkich trzech lat). Natomiast, najbardziej podobnymi obiektami (pod względem wszystkich 12 cech traktowanych łącznie) były A4B2C2 i A3B2C2 (w 2009), A4B2C2 i A3B1C2 (w 2010), A2B2C2 i A2B1C2 (w 2011) oraz A4B2C2 i A3B2C2 (dla trzech lat). Odległości Mahalanobisa pomiędzy poszczególnymi obiektami w poszczególnych latach prowadzenia obserwacji były dodatnio i istotnie statystycznie skorelowane. Słowa
EN
NiTi alloys are successfully used in engineering and medical applications because of their properties, such as shape memory effect, superelasticity or mechanical strength. A composite with Mg matrix, due to its vibration damping properties, can be characterized by low weight and good vibration damping properties. In this study, a combination of two techniques was used for successful fabrication of Mg composite reinforced by NiTi alloy preform. The porous preforms synthesized by Self-propagating Hightemperature Synthesis (SHS) from elemental powders were subsequently infiltrated with Mg by squeeze casting. The effects were examined with scanning electron microscope with EDS detector, X-ray diffraction and microindentation. The inspection has shown well-connected matrix and reinforcement; no reaction at the interface and open porosities fully infiltrated by liquid Mg. Moreover, analysis of samples’ fracture has exhibited that crack propagates inside the Mg matrix and there is no detachment of reinforcement.
EN
Light metal (aluminium and magnesium) matrix composites in particular are being increasingly used in various kinds of transportation vehicles. The properties of final products are closely related to the employed production technology. This paper presents a brief review of the technologies used in aluminium and magnesium matrix composite casting, with a focus on the risks and benefits of each technology.
PL
Kompozyty metalowe, a w szczególności o osnowie z metali lekkich (jak aluminium i magnez), są obecnie coraz częściej stosowane w różnego typu środkach transportu. Właściwości gotowych wyrobów są ściśle powiązane z ich technologią wytwarzania. W niniejszej pracy przedstawiono krótki opis technologii odlewów kompozytowych o osnowie aluminiowej i magnezowej, koncentrując się na wadach i zaletach poszczególnych technologii.
PL
Przedstawiono charakterystykę fizycznych i chemicznych właściwości magnezu i jego stopów, proces ich korozji i metody jej przeciwdziałania. Szczegółowo opisano proces plazmowego utleniania elektrolitycznego ze względu na jego szerokie zastosowanie do wytwarzania warstw ochronnych na magnezie i jego stopach. Przedstawiono podstawy teoretyczne tego procesu oraz omówiono wpływ elektrycznych i chemicznych parametrów na właściwości użytkowe wytwarzanych warstw konwersyjnych.
EN
A review, with 188 refs., of physical and chem. properties of the title metals, their susceptibility to corrosion as well as impact of chem. and elec. parameters of the process on the quality of the obtained protective layers.
10
EN
Amorphous materials based on magnesium are new materials for potential biomedical application, especially for new implants, as they bear resemblance to titanium implants. Mg66Zn30Ca4 alloy has specific properties, especially mechanical and corrosive, therefore, it has biomedical application as its properties are better than that of other materials. The following paper describes amorphous alloy based on magnesium, properties and shows how to produce amorphous samples of Mg66Zn30Ca4.
PL
Twardość wody, powodowana obecnością jonów wapnia i magnezu, nie jest czynnikiem stanowiącym zagrożenie zdrowia konsumentów. Jednakże woda o podwyższonej twardości może nie być akceptowana przez odbiorców z powodu wytrącania się osadów i wówczas zmniejszenie twardości wody staje się koniecznym warunkiem komfortu jej użytkowania. Zmiękczanie wody może być prowadzone na drodze chemicznej lub fizycznej, w takich procesach jak wymiana jonowa, procesy membranowe, strącanie chemiczne czy krystalizacja. Możliwości zmiękczania wody podziemnej metodą krystalizacji heterogenicznej, łącznie z usuwaniem związków żelaza i manganu, określono doświadczalnie w stacji pilotowej, której podstawowym elementem był reaktor ze złożem fluidalnym z piasku kwarcowego, pełniącego rolę zarodków krystalizacji węglanu wapnia. Twardość ogólna wody podziemnej wynosiła 160÷166 gCaCO3/m3, zawartość żelaza – 0,44÷0,66 gFe/m3, a manganu – 0,16÷0,23 gMn/m3. Do zmiękczania wody zastosowano ług sodowy (NaOH), dawkowany w ilości odpowiadającej w przybliżeniu dawce stechiometrycznej wymaganej do usunięcia jonów wapnia. W badaniach pilotowych nad zmiękczaniem wody podziemnej w procesie krystalizacji heterogenicznej z użyciem ługu sodowego wykazano możliwość zmniejszenia twardości ogólnej wody o 40% przy użyciu dawki NaOH o połowę mniejszej od stechiometrycznej. Stwierdzono selektywne usuwanie jonów wapnia, przy stosunkowo niewielkim zmniejszeniu zawartości jonów magnezu, a także jednoczesne usunięcie z wody związków żelaza i manganu. Przeprowadzona analiza porównawcza procesu krystalizacji heterogenicznej i nanofiltracji potwierdziła przydatność obu procesów do zmniejszania twardości wody wprowadzanej do systemu dystrybucji oraz jej negatywnych skutków.
EN
Hardness of water caused by calcium and magnesium salts does not pose any health risk to consumers. However, harder water may not be widely accepted due to the build-up of scale deposits. Hence, hardness reduction becomes a critical factor of water usage comfort. Water hardness may be reduced via chemical or physical processes, such as ion exchange, membrane processes, stripping or crystallization. Potential application of heterogeneous crystallization to groundwater hardness reduction, including iron and manganese removal, was determined empirically at the pilot station with fluidized bed reactor of arenaceous quartz, serving as a nuclei of crystallization for calcium carbonate. Total hardness of groundwater was ranging from 160 to 166 gCaCO3/m3, the iron content – from 0.44 to 0.66 gFe/m3, while the manganese – from 0.16 to 0.23 gMn/m3. Sodium hydroxide (NaOH) was used for the purpose of water softening, at the amount close to the stoichiometric dose required for the calcium ion removal. Pilot studies on groundwater softening using the heterogeneous crystallization with sodium hydroxide revealed a possibility to reduce the total water hardness by 40% at the half stoichiometric point. Selective calcium ion removal was demonstrated with relatively small reduction in magnesium content. Iron and manganese cations were co-removed. A comparative analysis of heterogeneous crystallization and nanofiltration confirmed suitability of the both processes for hardness reduction of water entering the distribution system and elimination of its adverse effects.
EN
The effect of the initial texture on the deformation mode and mechanical properties was studied in magnesium and its AZ61 alloy. Both materials had a very similar initial texture. Two cases were investigated: samples with a texture where the basal slip system was blocked, and samples having a texture where the basal slip system was allowed to activate. The samples were deformed by compression at room temperature at a strain rate of 10−3 s−1. It was found that the initial texture had a very strong impact on the deformation mode in magnesium; however, there was no effect of the initial texture on the deformation mode in the case of AZ61. The investigations were compared to simulations of texture evolution using the Taylor model. From the simulations, the Taylor factor and slip system activity were obtained. It was found that, in the case of magnesium, twinning or slip (both basal and non-basal) are the two main deformation modes, while in the case of AZ61, slip is the only main deformation mechanism despite the initial texture. The impact of the initial texture is discussed in more detail in the present study.
PL
W pracy badano wpływ początkowej tekstury na mechanizmy deformacji i właściwości mechaniczne magnezu i stopu magnezu AZ61. Zbadano dwa przypadki: próbki, w których bazalny system poślizgu został zablokowany, oraz próbki, w których bazalny system poślizgu mógł być aktywowany. Próbki odkształcano przez ściskanie w temperaturze pokojowej z prędkością odkształcania 10-3 s-1. Stwierdzono, że początkowa tekstura miała bardzo silny wpływ na sposób deformacji magnezu; jednak w przypadku AZ61 nie zauważono podobnego efektu wpływu początkowej tekstury na właściwości mechaniczne. Badania porównano z symulacjami ewolucji tekstury za pomocą modelu Taylora. Z symulacji uzyskano współczynnik Taylora i aktywności systemów poślizgu. Stwierdzono, że w przypadku magnezu, w zależności od początkowej tekstury, poślizg (zarówno w bazalnym systemie, jak i niebazalnych systemach poślizgu) oraz bliźniakowanie są dwoma głównymi mechanizmami deformacji, natomiast w przypadku AZ61 głównym mechanizmem deformacji, pomimo początkowej tekstury, jest tylko poślizg.
13
Content available remote Carbon fibre reinforced wheel for fuel ultra-efficient vehicle
EN
Due to municipal policies that are about to be legislated in many cities around the world, it may occur that habitants will be forced to commute in ultralight urban low-consuming cars. This paper covers the research concerning the innovative design, manufacturing method and the test of the wheel for such a vehicle. The design guidelines were as follows: elevated rigidity and durability, reduced weight and ease to adapt different types of hubs and powertrains. This was achieved by determining the forces acting on the wheel, examination of the characteristics of the possible materials and performing static finite element analysis simulations that were aimed to reveal stresses distribution and presumable failure points. Afterwards, the carbon fiber reinforced polymer disc wheel was manufactured and tested to compare the empirical deformations with the results of the simulations. The results proved that this type of wheel can be successfully used in ultralight passenger vehicle. The predicted weight reduction of such a wheel, in comparison to the wheels available on the market, may be about 40% due to using carbon fibre reinforced polymer and new, innovative solution - the magnesium hub, instead of aluminum, that is known to damp the vibration more efficiently and is easier to create a strong bond with the wheel.
EN
The traditional salt production in Indonesia was investigated to report the preparation and processing of salt, determine the characteristics of sea water and bittern as well as explore the potential of bittern management with appropriate technology. Field study and comprehensive analysis were performed so as to better understand the salt making, providing valuable information for the proposal of targeted management strategies in salt quality improvement and wastewater recovery. The results show that Na+, Cl– and Ca2+ in East Java Province seawater were found greater than the majority of values found in the literature. The highest concentrations of Na+, Cl– and Ca2+ were measured in Camplong-Sampang District. The highest concentrations of Mg2+ and trace metals were recorded in Panceng-Gresik District. The trace metals found in sea water and bittern need particular concern to be removed without disposing of sea water minerals. The potential number of bittern in Indonesia promoted the development of the bittern management for magnesium recovery and achieving marine environment sustainability. High purified material recovery can be achieved by using crystallization technology.
EN
Iron (Fe) and magnesium (Mg) deficiency in human diets is a widespread problem observed in various regions of the world. Insufficient Fe uptake results in the development of iron dependent anaemia and depressed physical and intellectual performance. In turn Mg deficiency is associated with alterations in neuromuscular and cardiovascular systems. An emerging alternative to traditional supplementation of these elements in the form of pills, liquids or effervescent tablets, is introduction of fortified food products. In present study we show that preincubation of soybean seeds in Fe and Mg solutions leads to elevated content of these elements in the seedlings. Importantly the pretreatment did not affect germination rate, seedlings growth or, with an exception of Fe supplementation at highest concentration, antioxidant capacity. The obtained results indicate that preincubation of seeds in Fe and Mg solutions may be a promising method of obtaining enriched soybean sprouts.
16
Content available remote Wpływ domieszek kilku metali na właściwości krzemianu trójwapniowego
PL
W pracy przedstawiono wyniki badań wpływu dodatków ZnO, MgO, Al2O3, Cr2O3 i 2% MgO + 2% Al2O3, odpowiadający syntetycznemu alitowi. Największą wytrzymałość miał zaczyn z C3S zawierający cynk, po 28 dniach z dodatkiem 2% ZnO; wynoszącą 101 MPa. Znacznie mniejszą wytrzymałość miały próbki z dodatkiem Al2O3, a najmniejszą miał zaczyn z C3S + 1% Cr2O3. Na drugim miejscu po cynku lokuje się "syntetyczny" alit, który zapewnia dużą wytrzymałość po 1 i 2 dniach, a taką samą jak 3% dodatek ZnO po 7 dniach. Dobrą wytrzymałość daje także dodatek 2% MgO, z wyjątkiem krótkich czasów dojrzewana. Mikrokalorymetria wykazała, że występuje dobra korelacja ciepła hydratacji z wytrzymałością, aczkolwiek nie ma korelacji okresu indukcji, który jest długi w przypadku cynku, natomiast zaczyn C3S + ZnO ma po 1 dniu dużą wytrzymałość. Badania mikrostruktury zaczynów wykazały, że cynk nie jest równomiernie rozmieszczony w kryształach krzemianu trójwapniowego, są kryształy, które w ogóle nie zawierają cynku. Spowodowało to podobne zróżnicowanie w fazie C-S-H; faza ta zawierająca cynk ma nietypową morfologię.
EN
In the paper the experimental results of the influence of ZnO, MgO, Al2O3 Cr2O3 and 2% MgO + 2%Al2O3 addition to C3S, the last one corresponding to synthetic alite, on the properties of these solid solutions are presented. The highest compressive strength had the paste of C3S + ZnO, after 28 days equal to 101 MPa. Significantly lower strength had the specimens with Al2O3 and the lowest the paste of C3S+ 1% Cr2O3. On the second place after zinc was the paste of “synthetic” alite which had the high strength after 1 and 2 days and the same as the sample of C3S + 3% ZnO after 7 days. Good strength the specimens of C3S + 2% MgO are also assuring, with exception of the short period of curing. The microcalorimetry had shown the good correlation of the heat of hydration with strength, however, there was no correlation of the induction period time with early strength of the paste from C3S + ZnO. Simultaneously the observation of the pastes microstructure had shown that zinc is not uniformly distributed among the tricalcium silicate crystals; there are particles which do not contains zinc. The similar differentiation of C-S-H phase was observed; this phase containing zinc has the untypical morphology.
EN
This work concentrates on the impact and contribution of zirconium carbide (ZrC) and magnesium to the mechanical and tribological properties of aluminium matrix composites. Distinctive weight portions of zirconium carbide, containing fixed weight fractions of magnesium and strengthening aluminium composites, were prepared utilising the entrenched cold-press sintering technique used in powder metallurgy. The uniform powder mixture was obtained by using planetary ball milling and it was then observed by using the scanning electron microscope technique. The hardness of the hybrid composite increased along with increase in the amount of the ZrC particle. The wear losses of sintered Al-Mg-ZrC composites were explored by directing sliding tests in pin-on-disc equipment. Hybridisation of reinforcements also decreased the wear loss of the composites at high sliding load and speed. This study reveals that the hybrid aluminium composite can be considered a unique material with high strength, low weight and wear resistance that will find their application in components to be used in the automobile and aero space engineering sectors.
EN
In this study, high performance magnesium-yttria nanocomposite’s room temperature, strength and ductility were significantly enhanced by the dispersion of nano-sized nickel particles using powder blending and a microwave sintering process. The strengthening effect of the dispersed nano-sized nickel particles was consistent up to 100°C and then it gradually diminished with further increases in the test temperature. The ductility of the magnesium-yttria nanocomposite remained unaffected by the dispersed nano-sized nickel particles up to 100°C. Impressively, it was enhanced at 150°C and above, leading to the possibility of the near net shape fabrication of the nanocomposite at a significantly low temperature.
EN
In the present study, an endeavour has been made to investigate the mechanical properties of hollow glass microspheres reinforced die cast magnesium alloy under vacuum die casting process. The particle size, mass fraction, stirring speed has been considered as input process parameters to analyze the mechanical properties such as hardness, compressive strength, porosity and density of the syntactic foams. Taguchi-Grey relational based multi response optimization has been utilized to compute the optimal process parameters and find the influence of those parameters on performance measures of casting process. From the experimental investigation, the optimal process parameters have been found as particle size (45 microns), mass fraction (20%) and stirring speed (600 rpm) among the chosen process parameters. The highest max–min indicates the particle size has higher influence on determining the mechanical properties of the syntactic foam owing to its importance on determining the porosity. It has been also observed that the density of syntactic foam decreases with increases in the mass percentage of hollow glass microspheres.
PL
Talerze dysków twardych zawierają kobalt i nikiel, a nośniki najnowszej generacji także platynę i ruten. Metale te znajdują się w cienkich (nanometrycznych) warstwach magnetycznych. W artykule omówiono budowę i skład talerzy dysków twardych oraz przedstawiono wyniki doboru roztworu trawiącego. Stwierdzono, że w roztworach HCI następuje roztwarzanie podłoża Al-Mg uszkodzonych mechanicznie talerzy. Powłoka magnetyczna jest odporna na działanie stężonych kwasów i zasad.
EN
Computer disc platters contain cobalt and nickel, and the carries of the lastes generatio also platinum and ruthenium. The metals are in thin (nano-metric) magnetic layers. The structure and composition of platters are discussed in this paper and the results of the selection of the etching solution are presented. It has been found that HCI solution can dissolve selectively the Al-Mg substrate of mechanically damaged platters. The magnetic coating is resistant to the action of concentrated acids and bases.
first rewind previous Strona / 9 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.