Nanomaterials are being used increasingly for commercial purposes, yet little is known about the potential health hazards such materials may pose to consumers and workers. Here we show that nano-sized titanium dioxide (TiO 2 ), which is used widely as a photo-catalyst and in consumer products, administered subcutaneously to pregnant mice is transferred to the offspring and affects the genital and cranial nerve systems of the male offspring. Nanoparticles identified as TiO 2 by energy-dispersive X-ray spectroscopy were found in testis and brain of exposed 6-week-old male mice. In the offspring of TiO 2 -injected mice, various functional and pathologic disorders, such as reduced daily sperm production and numerous caspase-3 (a biomarker of apoptosis) positive cells in the olfactory bulb of the brain, were observed. Our findings suggest the need for great caution to handle the nanomaterials for workers and consumers.

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We propose differential holography as a method to overcome the long-standing forward-scattering problem in photoelectron holography and related techniques for the three-dimensional imaging of atoms. Atomic images reconstructed from experimental and theoretical Cu 3p holograms from Cu(001) demonstrate that this method suppresses strong forward-scattering effects so as to yield more accurate three-dimensional images of side-and back-scattering atoms.PACS numbers: 61.14. -x, 42.40.-i Holography [1] is a method of recording both the amplitudes and phases of waves scattered by an object illuminated with coherent radiation, and using this information to directly construct a three-dimensional image of the object. Szöke [2] first suggested that coherent outgoing waves from atomically-localized sources of photoelectrons, fluorescent x-rays, and γ-rays could be used to achieve atomic-scale holography. This idea was initially demonstrated theoretically for the case of photoelectrons by Barton [3], and then extended into a multienergy format by Barton and Terminello and by Tong and co-workers [4]. By now several experimental approaches to such atomic-resolution holography have been demonstrated, including photoelectrons [5,6,7,8] Among these methods, photoelectron holography (PH) has the advantages of being capable of studying the local atomic structure around each type of emitter without requiring long-range order and of distinguishing emitters through core-level binding-energy shifts [8]. Photoelectron holograms also show strong modulations of up to ±50%, so such effects are easily measurable. However, PH can suffer from serious image aberrations due to the strength of electron scattering. The atomic scattering factor f is a highly anisotropic function of scattering angle, and can depend strongly on electron kinetic energy E k . In particular, as E k increases above a few hundred eV, f becomes more and more significant in the forward direction, resulting in a strong forward-scattering (FS) peak [16] that can induce image aberrations. Beyond this, PH also can suffer from multiple-scattering (MS) effects due to the scattering strength.Various reconstruction algorithms and measurement methods [4,5,7,17] have been proposed to correct for the anisotropic f and MS effects, some of which can be summarized viawhere U is the image intensity at position r, χ is the normalized 3D hologram, and the function or operator W permits describing the difference between algorithms, with W =1 in the original multi-energy formulations [4]. One alternative algorithm [5] sets W = f −1 k, θ k r so as to divide out the anisotropic f , where θ k r is the angle between r and k. In another algorithm [7] based on the more ideal electron back scattering (BS), a window function for W that limits the integral in Eq. (1) to be in a small cone ofk around −r is chosen to emphasize the imaging of BS atoms. Although successful in several applications [7,18], it is difficult to apply this smallcone method to many systems where the imaging of FS or even side...

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