15,327 research outputs found
Ising-type Magnetic Anisotropy in CePdAs
We investigated the anisotropic magnetic properties of CePdAs by
magnetic, thermal and electrical transport studies. X-ray diffraction confirmed
the tetragonal ThCrSi-type structure and the high-quality of the single
crystals. Magnetisation and magnetic susceptibility data taken along the
different crystallographic directions evidence a huge crystalline electric
field (CEF) induced Ising-type magneto-crystalline anisotropy with a large
-axis moment and a small in-plane moment at low temperature. A detailed CEF
analysis based on the magnetic susceptibility data indicates an almost pure
CEF ground-state doublet with the dominantly
and the doublets at 290 K and 330
K, respectively. At low temperature, we observe a uniaxial antiferromagnetic
(AFM) transition at K with the crystallographic -direction being
the magnetic easy-axis. The magnetic entropy gain up to reaches almost
indicating localised -electron magnetism without significant
Kondo-type interactions. Below , the application of a magnetic field along
the -axis induces a metamagnetic transition from the AFM to a
field-polarised phase at T, exhibiting a text-book example
of a spin-flip transition as anticipated for an Ising-type AFM.Comment: 9 Pages, 8 figure
Grain and straw yield of tropical rainfed lowland rice in brazil under diferent irrigation regimes.
The objective of this study was the evaluate response of rice to different irrigation regimes and doses of nitrogen under tropical floodplain conditions, during the rainy season in the savannah biome of Brazil.IRC14-1541
Growth of a bonelike apatite on chitosan microparticles after a calcium silicate treatment
Bioactive chitosan microparticles can be prepared successfully by treating them with a calcium silicate solution and then subsequently
soaking them in simulated body fluid (SBF). Such a combination enables the development of bioactive microparticles that can be used
for several applications in the medical field, including injectable biomaterial systems and tissue engineering carrier systems. Chitosan
microparticles, 0.6 lm in average size, were soaked either for 12 h in fresh calcium silicate solution (condition I) or for 1 h in calcium
silicate solution that had been aged for 24 h before use (condition II). Afterwards, they were dried in air at 60 !C for 24 h. The samples
were then soaked in SBF for 1, 3 and 7 days. After the condition I calcium silicate treatment and the subsequent soaking in SBF, the
microparticles formed a dense apatite layer after only 7 days of immersion, which is believed to be due to the formation of silanol (Si–
OH) groups effective for apatite formation. For condition II, the microparticles successfully formed an apatite layer on their surfaces in
SBF within only 1 day of immersion.I.B.L. thanks the Portuguese Foundation for Science and Technology (FCT), for providing her a PhD scholarship (SFRH/BD/9031/2002), the European Union funded STREP Project HIPPOCRATES (NMP3-CT-2003-505758) and the European NoE EXPERTISSUES (NMP3-CT-2004-500283)
Biomimetic apatite formation on different polymeric microspheres modified with calcium silicate solutions
Proceedings of the 18th International Symposium on Ceramics in Medicine, The Annual Meeting of the International Society for Ceramics in Medicine (ISCM), Kyoto, Japan, 5-8 December 2005. Published in : Key Enggineering Materials, vol. 309 - 311Bioactive polymeric microspheres can be produced by pre-coating them with a calcium
silicate solution and the subsequent soaking in a simulated body fluid (SBF). Such combination
should allow for the development of bioactive microspheres for several applications in the medical
field including tissue engineering. In this work, three types of polymeric microspheres with different
sizes were used: (i) ethylene-vinyl alcohol co-polymer (20-30 'm), (ii) polyamide 12 (10-30 'm) and
(iii) polyamide 12 (300 'm). These microspheres were soaked in a calcium silicate solution at 36.5ºC
for different periods of time under several conditions. Afterwards, they were dried in air at 100ºC for
24 hrs. Then, the samples were soaked in SBF for 1, 3 and 7 days. Fourier transformed infrared
spectroscopy, thin-film X-ray diffraction, and scanning electron microscopy showed that after the
calcium silicate treatment and the subsequent soaking in SBF, the microspheres successfully formed a
bonelike apatite layer on their surfaces in SBF within 7 days due to the formation of silanol (Si-OH)
groups that are quite effective for apatite formation.I. B. Leonor thanks the Portuguese Foundation for Science and Technology (FCT) for providing her a PhD scholarship (SFRH/BD/9031/2002) and the European Union funded STREP Project HIPPOCRATES (NMP3-CT-2003-505758) and the European NoE EXPERTISSUES (NMP3-CT-2004-500283)
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