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171.
Highly sensitive room-temperature method of non-invasive in vivo detection of magnetic nanoparticles
Maxim P. Nikitin Petr M. Vetoshko Petr I. Nikitin 《Journal of magnetism and magnetic materials》2009,321(10):1658-1661
Methods of non-invasive in vivo quantification of magnetic nanoparticles (MP) have been proposed and realized. The methods are based on non-linear MP magnetization at two frequencies and measuring the response at combinatorial frequencies. The first method is developed for real-time study of MP dynamics and their clearance from the blood system of animals. High sensitivity of 3 ng of Fe3O4 in 0.1 ml was achieved for MP detection in mice tail veins. The second technique is proposed for MP detection inside animal tissues by an external probe. The proposed methods could essentially widen capabilities of biomedical research which involves magnetic nanoparticles. 相似文献
172.
Vibrational bands of L ‐tryptophan which was adsorbed on Ag nanoparticles (∼10 nm in diameter) have been investigated in the spectral range of 200–1700 cm−1 using surface‐enhanced Raman scattering (SERS) spectroscopy. Compared with the normal Raman scattering (NRS) of L ‐tryptophan in either 0.5 M aqueous solution (NRS‐AS) or solid powder (NRS‐SP), the intensified signals by SERS have made the SERS investigation at a lower molecular concentration (5 × 10−4 M ) possible. Ab initio calculations at the B3LYP/6‐311G level have been carried out to predict the optimal structure and vibrational wavenumbers for the zwitterionic form of L ‐tryptophan. Facilitated with the theoretical prediction, the observed vibrational modes of L ‐tryptophan in the NRS‐AS, NRS‐SP, and SERS spectra have been analyzed. In the spectroscopic observations, there are no significant changes for the vibrational bands of the indole ring in either NRS‐AS, NRS‐SP, or SERS. In contrast, spectral intensities involving the vibrations of carboxylate and amino groups are weak in NRS‐AS and NRS‐SP, but strong in SERS. The intensity enhancement in the SERS spectrum can reach 103–104‐fold magnification. On the basis of spectroscopic analysis, the carboxylate and amino groups of L ‐tryptophan are determined to be the preferential terminal groups to attach onto the surfaces of Ag nanoparticles in the SERS measurement. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
173.
Dailly A. Schneider R. Billaud D. Fort Y. Ghanbaja J. 《Journal of nanoparticle research》2003,5(3-4):389-393
A novel chemical reduction method using an activated alkaline hydride (LiH or NaH-t-BuONa) in tetrahydrofuran solvent has been applied to antimony salt reduction. X-ray diffraction and transmission electron microscopy studies have been carried out to characterize the morphology and structure of the materials. Alkali hydride nature influence has been proved. In both cases the process allows to prepare antimony particles in nanometer range from few nanometers to about 20nm which could be used as anodic materials for lithium–ion batteries. With lithium hydride well-crystallized particles inclined to agglomeration were observed whereas finely dispersed amorphous particles were pointing out after activated sodium hydride reduction. 相似文献
174.
O. N. Bakharev N. Zelders H. B. Brom A. Schnepf H. Schnöckel L. Jos de Jongh 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,24(1-3):101-104
We present
69,71Ga-NMR experiments on
microcrystalline samples of the recently discovered
supramolecular compound Ga
84
[
N
(
SiMe
3
)
2
]
20
Li
6
Br
2
(
thf
)
20
.
2
toluene, which is composed of
ligand-coordinated Ga84 metal clusters,
packed together in a fully ordered crystalline matrix. The
compound is highly conducting and even shows superconductivity
below T
c
~ 7.2 K. Our preliminary
results between 10-300 K show a metallic-like behavior: the
nuclear spin-lattice relaxation rate T
1
-1
follows the Korringa law
69
(
T
1
T
)
-1
= 0.36 s
-1
K
-1
, but with a relaxation rate approximately three
times smaller than in bulk -Ga
metal. No quantum-size effects are observed, the Korringa law
being followed down to 10 K, whereas the quantum-gaps for
individual clusters should amount to ~
10
3
K. These results therefore suggest a transport process based on
intermolecular charge transfer, similar as in alkali-doped
fullerenes and silicon-clathrates. 相似文献
175.
RuS2 nanoparticles, smaller than 3 nm in diameter, were prepared by H2S gas injection into the AOT/isooctane reverse micellar solution containing RuCl3 aqueous solution. The nanoparticle size was found to be independent of the Wo (water content) value of the reverse micellar system, as shown by TEM observation. The recovery and immobilization of the RuS2 nanoparticles from reverse micelles onto thiol-modified polystyrene particles (PSt-SH) were successfully carried out, by the addition of PSt-SH into the reverse micellar solution under conditions of mild stirring. The resulting composites, PSt-RuS2, showed photocatalytic activity for H2 generation form aqueous solution containing 2-propanol and Na2SO3 as sacrificial electron donors. 相似文献
176.
C. Bréchignac Ph. Cahuzac F. Carlier C. Colliex M. de Frutos N. Kébaïli J. Le Roux A. Masson B. Yoon 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,24(1-3):265-268
We studied shape relaxation of nano-fractal islands,
during annealing, after their growth from antimony cluster
deposition on graphite surface. Annealing at
180°C shows evidence of an increase
of the fractal branch width with time followed by branch
fragmentation, without changing the fractal dimension. The time
evolution of the width of the arm suggests the surface
self-diffusion mechanism as the main relaxation process. With
Monte Carlo simulations, we confirmed the observed behavior.
Comparison is done with our previous results on fragmentation of
nano-fractal silver islands when impurity added to the incident
cluster promotes rapid fragmentation by surface self-diffusion
enhancement [1]. 相似文献
177.
P. Scheier K. Sattler 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,24(1-3):347-349
Monolayer and bi-layer silicon nanoparticle (SiNP) films
with wide band gaps (up to 4 eV) have been produced in UHV with
narrow size distributions of particles with 2-4 nm diameters and
were studied using scanning tunneling microscopy (STM) and
spectroscopy (STS). The films then were manipulated by applying
different values for the tunneling resistance. Nanoparticle
fusion and fission processes allow to shape the particles in the
films in various ways and to write in white and black on the
film template. 相似文献
178.
Matsuyama Kiyoshi Mishima Kenji Hayashi Ken-ichiro Matsuyama Hideto 《Journal of nanoparticle research》2003,5(1-2):87-95
A novel preparation method is reported for the microencapsulation of TiO2 nanoparticles by rapid expansion of supercritical solution with a nonsolvent. A suspension of TiO2 nanoparticles in carbon dioxide containing a cosolvent and dissolved polymer is sprayed through a nozzle to atmospheric pressure. After rapid expansion, polymer microspheres were obtained. The microspheres do not tend to agglomerate, since the pure cosolvent is a nonsolvent for the polymer. The structure and morphology of microspheres were investigated by SEM, TEM and XRD. The obtained polymer microspheres are microcapsules of TiO2 nanoparticles. The mean particle diameter and particle size distribution of microcapsules, could be controlled by changing the polymer concentration, pre-expansion pressure, temperature and injection distance. The polymer feed compositions are more effective than other factors on the control of particle size. 相似文献
179.
金纳米粒子光学性质中的尺寸和形状效应 总被引:4,自引:2,他引:4
纳米尺度的金属及半导体呈现出特殊的光学、电学及磁学性质,采用近年发展起来的离散偶极近似(DDA)的方法,我们分析了金纳米粒子的尺寸及形状对其光学性质的影响。粒子周围介质的影响在文中亦作了分析。计算结果显示,金纳米粒子的等离子体吸收带同时受到粒子尺寸和形状的影响,但来自形状的影响更为明显。与米氏理论及扩展的甘氏理论相比较,DDA方法在粒子尺寸不再远小于入射光波长的时候更准确,并能应用于任何形状的纳米粒子。理论计算与实验结果能较好的吻合。 相似文献
180.
Jin-Seung Jung Kyong-Hoon Choi Yong-Rok Kim Leszek Malkinski Weilie Zhou Charles J O'Connor 《Journal of Physics and Chemistry of Solids》2003,64(3):385-390
Superparamagnetic nickel nanoparticles were prepared by incorporating nickel ion into AlMCM41 as a nanoreactor and then reduced with sodium borohydride or H2 gas. Products were characterized by elemental analysis, transmission electron microscopy, X-ray powder diffraction, and magnetic susceptibility. The nickel particle size and blocking temperature depend on the reduction method. 相似文献