Comparative biological effects of spherical noble metal nanoparticles (Rh, Pd, Ag, Pt, Au) with 4–8 nm diameter

For a comparative cytotoxicity study, nanoparticles of the noble metals Rh, Pd, Ag, Pt, and Au (spherical, average diameter 4 to 8 nm) were prepared by reduction in water and colloidally stabilized with poly(N-vinyl pyrrolidone) (PVP). Thus, their shape, size, and surface functionalization were all the same. Size and morphology of the nanoparticles were determined by dynamic light scattering (DLS), analytical disc centrifugation (differential centrifugal sedimentation, DCS), and high-resolution transmission electron microscopy (HRTEM). Cell-biological experiments were performed to determine the effect of particle exposure on the viability of human mesenchymal stem cells (hMSCs). Except for silver, no adverse effect of any of the metal nanoparticles was observed for concentrations up to 50 ppm (50 mg L−1) incubated for 24 h, indicating that noble metal nanoparticles (rhodium, palladium, platinum, gold) that do not release ions are not cytotoxic under these conditions.

Preferred Orientation, PDF and Debye Equation

The effect of preferred orientation is currently neglected in the Debye Equation and PDF calculations. This is to a large extend justified, especially for the PDF, as the scattering by large sample volumes is detected by an area detector. The integration of powder rings reduces the effects of preferred orientation. As more laboratory PDF measurements become available that use linear position sensitive detectors or single counter detectors, preferred orientation needs to be reconsidered. A Rietveld calculation treats preferred orientation by multiplying the Bragg intensity by a factor that depends on the angle between the reciprocal space vector and the preferred orientation axis. The powder intensity I(Q) is thus multiplied by a complex function that depends at each Q on the degree of preferred orientation, the lattice parameters, reflection multiplicity etc. The effect on the PDF is therefore the convolution by the Fourier transform of this complex function. The Debye equation is derived from a spherical average of the scattering intensity of a finite object. Thus completely random orientation of the powder grains is implicitly assumed. Both, the Debye algorithm and the PDF algorithm calculate the powder pattern, respectively the PDF from a histogram of interatomic distances, which correspond to a spherical average of all interatomic distance vectors. This histogram does not allow for a Rietveld preferred orientation correction. The effects of preferred orientation on the PDF will be presented on the basis of simulated diffraction pattern. An algorithm to describe the changes in the PDF and the inverse sine Fourier transform as a convenient tool to calculate the powder diffraction pattern will be introduced. This is a good alternative to the Debye equation and allows to take preferred orientation into account both for the PDF and the calculated powder.

PREPARATION AND PROPERTY STUDIES OF Zn3P2/CALCIUM ALGINATE

Zn 3 P 2 is an acute and effective rodenticide used widely to protect grains in stores and domestically to kill rodents. This study aims to postpone the time of poisoning symptoms after eating Zn 3 P 2 and improve the effect of killing rodents. Zn 3 P 2/calcium alginate ( Zn 3 P 2/ CA ) was synthesized through the reaction of sodium alginate and calcium chloride by the reversed-phase microemulsion method and then loaded with Zn 3 P 2 technical. It was characterized by X-ray diffractometer, laser particle size analyzer, scanning electron microscope (SEM) and transmission electron microscopy (TEM). The drug loading capacity, slow-controlled release performances and toxic effects were also investigated. The results showed that Zn 3 P 2/ CA was spherical, average particle size was 353.9 nm, and particle dispersion index (PDI) was 0.195. The mass ratios of calcium alginate and Zn 3 P 2 technical ( CA / Zn 3 P 2) had significant impacts to drug loading capacity and slow-controlled release performances of Zn 3 P 2/ CA . The palatability and efficacy of Zn 3 P 2/ CA were significantly improved and enhanced compared with Zn 3 P 2 technical. The results showed that Zn 3 P 2/ CA presented high loading efficiency, commendable sustained-release performance and good environmental compatibility, and this delivery carrier may be extended to other slow-controlled release and high-efficient pesticide formulation in future.

A strong law of large numbers for harmonizable isotropic random fields

The class of harmonizable fields is a natural extension of the class of stationary fields. This paper considers a strong law of large numbers for the spherical average of a harmonizable isotropic random field.