Kerry Siebein

Distribution of silver nanoparticles in pregnant mice and developing embryos

Abstract The objective of this study was to evaluate the distribution of silver nanoparticles (NPs) in pregnant mice and their developing embryos. Silver NPs (average diameter 50 nm) were intravenously injected into pregnant CD-1 mice on gestation days (GDs) 7, 8, and 9 at dose levels of 0, 35, or 66 μg Ag/mouse. Mice were euthanised on GD10, and tissue samples were collected and analysed for silver content. Compared with control animals injected with citrate buffer vehicle, silver content was significantly increased (p < 0.05) in nearly all tissues from silver NP-treated mice. Silver accumulation was significantly higher in liver, spleen, lung, tail (injection site), visceral yolk sac, and endometrium compared with other organs from silver NP-treated mice. Furthermore, silver NPs were identified in vesicles in endodermal cells of the visceral yolk sac. In summary, the results demonstrated that silver NPs distributed to most maternal organs, extra-embryonic tissues, and embryos, but did not accumulate significantly in embryos.

Cross-sectional transmission electron microscopy method and studies of implant damage in single crystal diamond

Few transmission electron microscopy (TEM) studies of single crystal diamond have been reported, most likely due to the time and difficulty involved in sample preparation. A method is described for creating a TEM cross section of single crystal diamond using a focused ion beam and in situ lift-out. The method results in samples approximately 10μm long by 3μm deep with an average thickness of 100–300nm. The total time to prepare a cross-sectional TEM sample of diamond is less than 5h. The method also allows for additional thinning to facilitate high resolution TEM imaging, and can be applied to oddly shaped diamond samples. This sample preparation technique has been applied to the study of ion implantation damage in single crystal diamond and its evolution upon annealing. High-pressure–high-temperature diamonds were implanted with Si+ at an energy of 1MeV and a temperature of 30°C. One sample, with a (110) surface, was implanted with a dose of 1×1014Sicm−2 and annealed at 950°C for 10 and 40min. No signifi...

Characterization of Nanomaterials for Toxicological Studies

The scientific community, regulatory agencies, environmentalists, and most industry representatives all agree that more effort is required to ensure the responsible and safe development of new nanotechnologies. Characterizing nanomaterials is a key aspect in this effort. There is no universally agreed upon minimum set of characteristics although certain common properties are included in most recommendations. Therefore, characterization becomes more like a puzzle put together with various measurements rather than a single straightforward analytical measurement. In this chapter, we emphasize and illustrate the important elements of nanoparticle characterization with a systematic approach to physicochemical characterization. We start with an overview describing the properties that are most significant to toxicological testing along with suggested methods for characterizing an as-received nanomaterial and then specifically address the measurement of size, surface properties, and imaging.

Solid Phase Crystallization (SPC) of a-Si Thin Film Induced by a Novel Approach for Photovoltaic Devices

The solid phase crystallization (SPC) of amorphous silicon thin films by a novel modification of nucleation step was investigated at low temperature. The thin film consists of polycrystalline nanoparticles embedded in an amorphous matrix which can act as nuclei, resulting in a lower thermal energy for the nucleation. Thus, this energy can shorten the transition time from amorphous to polycrystalline silicon and lower the processing temperature. The crystallinity and the crystallized volume fraction of silicon thin film annealed by the conventional furnace have been extensively studied by XRD and HRTEM. It was believed that high quality Si nanoparticles would act as nuclei for growth of crystalline Si, thus removing the high temperature requirement for nucleation. The crystalline films induced by nanoparticles can be used for the photovoltaic devices on glass substrates at a maximum temperature of 530oC.