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471.
Eszter Boros Alice M. Bowen Lee Josephson Neil Vasdev Jason P. Holland 《Chemical science》2015,6(1):225-236
A novel reaction for chelate-free, heat-induced metal ion binding and radiolabeling of ultra-small paramagnetic iron oxide nanoparticles (USPIOs) has been established. Radiochemical and non-radioactive labeling studies demonstrated that the reaction has a wide chemical scope and is applicable to p-, d- and f-block metal ions with varying ionic sizes and formal oxidation states from 2+ to 4+. Radiolabeling studies found that 89Zr–Feraheme (89Zr–FH or 89Zr–ferumoxytol) can be isolated in 93 ± 3% radiochemical yield (RCY) and >98% radiochemical purity using size-exclusion chromatography. 89Zr–FH was found to be thermodynamically and kinetically stable in vitro using a series of ligand challenge and plasma stability tests, and in vivo using PET/CT imaging and biodistribution studies in mice. Remarkably, ICP-MS and radiochemistry experiments showed that the same reaction conditions used to produce 89Zr–FH can be employed with different radionuclides to yield 64Cu–FH (66 ± 6% RCY) and 111In–FH (91 ± 2% RCY). Electron magnetic resonance studies support a mechanism of binding involving metal ion association with the surface of the magnetite crystal core. Collectively, these data suggest that chelate-free labeling methods can be employed to facilitate clinical translation of a new class of multimodality PET/MRI radiotracers derived from metal-based nanoparticles. Further, this discovery is likely to have broader implications in drug delivery, metal separation science, ecotoxicology of nanoparticles and beyond. 相似文献
472.
Harekrishna Bar Dipak Kr. Bhui Gobinda P. Sahoo Priyanka Sarkar Santanu Pyne Ajay Misra 《Colloids and surfaces. A, Physicochemical and engineering aspects》2009,348(1-3):212-216
An eco-friendly process for rapid synthesis of silver nanoparticles has been reported using aqueous seed extract of Jatropha curcas. Formation of stable silver nanoparticles at different concentration of AgNO3 gives mostly spherical particles with diameter ranging from 15 to 50 nm. The resulting silver particles are characterized using HRTEM, XRD and UV–vis spectroscopic techniques. XRD study shows that the particles are crystalline in nature with face centered cubic geometry. 相似文献
473.
Péter Buglyó Eszter Márta Nagy Etelka Farkas Imre Sóvágó Daniele Sanna Giovanni Micera 《Polyhedron》2007
Complex formation of primary dipeptide hydroxamic acids, L-Ala-L-AlaNHOH and L-Ala-L-SerNHOH, as well as the corresponding Z-protected ones, Z-L-Ala-L-AlaNHOH and Z-L-Ala-L-SerNHOH (Z = benzyloxycarbonyl), with iron(III), aluminium(III), nickel(II), copper(II) and zinc(II) was studied in aqueous solution by pH-potentiometric and spectroscopic (UV–Vis, EPR, CD, 1H NMR) methods. The exclusive formation of [O,O] chelated hydroxamate complexes was found with iron(III) and aluminium(III) with all the ligands. Formation of linkage isomers with the involvement of either [O,O] hydroxamate or [NH2,CO] chelates was detected both in the zinc(II)-L-Ala-L-AlaNHOH and -L-Ala-L-SerNHOH systems. Upon increasing the pH, none of these chelating sets are capable of preventing the hydrolysis of the metal ion. The formation of stable complexes was found in the nickel(II) and copper(II) systems above pH ∼ 6 with a [NH2, Namide, Nhydrox.] binding mode after deprotonation and coordination of the peptide amide and the hydroxamate group. With an excess of copper(II), the formation of trinuclear [Cu3HxL2]x+4 type (x = −4 to −6) complexes as the major species was also detected. Blocking the terminal amino group in the Z-protected ligands results in a dramatic decrease of the nickel(II) and zinc(II) binding strengths, and insoluble complexes with copper(II). No indication was found for the role of the hydroxyl group of the serine moiety in metal ion binding. 相似文献
474.
Christian von Lücken Benjamín Barán Carlos Brizuela 《Computational Optimization and Applications》2014,58(3):707-756
Multi-objective evolutionary algorithms (MOEAs) are well-suited for solving several complex multi-objective problems with two or three objectives. However, as the number of conflicting objectives increases, the performance of most MOEAs is severely deteriorated. How to improve MOEAs’ performance when solving many-objective problems, i.e. problems with four or more conflicting objectives, is an important issue since a large number of this type of problems exists in science and engineering; thus, several researchers have proposed different alternatives. This paper presents a review of the use of MOEAs in many-objective problems describing the evolution of the field, the methods that were developed, as well as the main findings and open questions that need to be answered in order to continue shaping the field. 相似文献
475.
Eszter Gselmann 《Results in Mathematics》2014,65(1-2):95-103
The main purpose of this note is to investigate the stability problem in a certain class of partial differential equations. 相似文献
476.
477.
This paper studies a queuing model where two customer classes compete for a given resource and each customer is dynamically quoted a menu of price and leadtime pairs upon arrival. Customers select their preferred pairs from the menu and the server is obligated to meet the quoted leadtime. Customers have convex–concave delay costs. The firm does not have information on a given customer’s type, so the offered menus must be incentive compatible. A menu quotation policy is given and proven to be asymptotically optimal under traditional large-capacity heavy-traffic scaling. 相似文献
478.
P. Maák G. Kurdi A. Barócsi K. Osvay A.P. Kovács L. Jakab P. Richter 《Applied physics. B, Lasers and optics》2006,82(2):283-287
Our paper deals with temporal shaping of ultrashort pulses by direct spectral filtering performed with bulk acousto-optic
filters using noncollinear geometry. This geometry allows arbitrary optical pulse repetition rate and high diffraction efficiency
at relatively large optical apertures. A theoretical model of the pulse shaper is presented, emphasizing the degrees of freedom
in this shaping technique. Phase and angular dispersion effects are analyzed, and experimental results on generating controllable
pulse trains are presented.
PACS 42.65.Re; 42.79.J 相似文献
479.
Liang Di Chapman David C. Li Youli Oakley Douglas C. Napoleone Tony Juodawlkis Paul W. Brubaker Chad Mann Carl Bar Hanan Raday Omri Bowers John E. 《Applied Physics A: Materials Science & Processing》2011,102(1):213-217
β-SiC nanowires were synthesized by a simple carbothermal reduction of carbonaceous silica xerogel. The morphology and structure
of the nanowires were investigated by X-ray diffraction, scanning electron microscope and transmission electron microscopy.
The results showed that the nanowires were hexagonal prism-shaped hierarchical nanostructures. The typical stacking faults
and twin defects of SiC nanowires were also observed. Band-gap characterization and photoluminescence properties of SiC nanowires
were investigated by UV-vis absorption spectroscopy and fluorescence photometry, respectively. The results showed the SiC
nanowire was an indirect transition semiconductor and the band gap energy for the SiC nanowires was 2.85 eV. The photoluminescence
peak value at 470 nm (2.64 eV) originating from the SiC nanowires was a little higher than the value of band-gap energy. 相似文献
480.
The structure of trans-1,4-dibromo-1,4-dicarboxymethylcyclohexane (I) has been determined by single crystal x-ray diffraction. The molecules, located on symmetry centers, are in the rigid chair conformation with the Br and COOCH3 axial and equatorial, respectively. The molecular geometry observed in the crystal is similar to that calculated for the isolated molecule using ab initio calculations performed at the HF/6-31(d) level. A peculiar arrangement of the carboxymethyl substituents, along with short contacts involving the Br atoms, seem to play a role in the stabilization of the crystalline structure. 相似文献