Nobumichi Tamura

Bio: Nobumichi Tamura is an academic researcher from Lawrence Berkeley National Laboratory. The author has contributed to research in topics: Electromigration & Stress (mechanics). The author has an hindex of 52, co-authored 354 publications receiving 9855 citations. Previous affiliations of Nobumichi Tamura include Centre national de la recherche scientifique & Kyoto University.

Quantitative Speciation of Heavy Metals in Soils and Sediments by Synchrotron X-ray Techniques

Abstract: Human societies have, in all ages, modified the original form of metals and metalloids in their living environment for their survival and technical development. In many cases, these anthropogenic activities have resulted in the release into the environment of contaminants that pose a threat to ecosystems and public health. Examples of local and global pollution are legion worldwide, and the reader of the environmental science literature is forever faced with ever more alarming reports on hazards due to toxic metals. For example, extensive mining and associated industrial activities have introduced large amounts of metal contaminants in nature at the local, but also global, scale since anthropogenic metals are detected in remote areas including Greenland ice (Boutron et al. 1991). Industrialized countries have countless polluted sites, and the major consequence in terms of contamination by heavy metals are areas of wasteland and sources of acid and metal-rich runoff from tailings piles and waste-rock heaps, and the subsequent pollution of coastal areas. Water supplies in many areas of many countries are also extensively polluted or threatened by high concentration of metal(loid)s, sometimes from natural sources, but most often from the activities of humans (Smedley and Kinniburgh 2002). Pollution of ground and surface waters, and hence of lands, by arsenic from alluvial aquifers in the Bengal Delta plain and in Vietnam are probably the two most catastrophic actual examples of the second type, where a modification of the chemistry of deep sediment layers by intensive well drillings and pumping of drinking water has led to vast arsenic remobilization and poisoning of ecosystems (Chatterjee et al. 1995; Nickson et al. 1998; Berg et al. 2001). Soils and sediments, being at the interface between the geosphere, the atmosphere, the biosphere and the hydrosphere, represent the major sinks for anthropogenic metals released to …

Synchrotron X-ray Analytical Techniques for Studying Materials Electrochemistry in Rechargeable Batteries

Abstract: Rechargeable battery technologies have ignited major breakthroughs in contemporary society, including but not limited to revolutions in transportation, electronics, and grid energy storage The remarkable development of rechargeable batteries is largely attributed to in-depth efforts to improve battery electrode and electrolyte materials There are, however, still intimidating challenges of lower cost, longer cycle and calendar life, higher energy density, and better safety for large scale energy storage and vehicular applications Further progress with rechargeable batteries may require new chemistries (lithium ion batteries and beyond) and better understanding of materials electrochemistry in the various battery technologies In the past decade, advancement of battery materials has been complemented by new analytical techniques that are capable of probing battery chemistries at various length and time scales Synchrotron X-ray techniques stand out as one of the most effective methods that allow for near

Effect of surface microstructure on electrochemical performance of garnet solid electrolytes.

Abstract: Cubic garnet phases based on Al-substituted Li7La3Zr2O12 (LLZO) have high ionic conductivities and exhibit good stability versus metallic lithium, making them of particular interest for use in next-generation rechargeable battery systems. However, high interfacial impedances have precluded their successful utilization in such devices until the present. Careful engineering of the surface microstructure, especially the grain boundaries, is critical to achieving low interfacial resistances and enabling long-term stable cycling with lithium metal. This study presents the fabrication of LLZO heterostructured solid electrolytes, which allowed direct correlation of surface microstructure with the electrochemical characteristics of the interface. Grain orientations and grain boundary distributions of samples with differing microstructures were mapped using high-resolution synchrotron polychromatic X-ray Laue microdiffraction. The electrochemical characteristics are strongly dependent upon surface microstructure, ...

Lattice strain causes non-radiative losses in halide perovskites

Abstract: Halide perovskites are promising semiconductors for inexpensive, high-performance optoelectronics. Despite a remarkable defect tolerance compared to conventional semiconductors, perovskite thin films still show substantial microscale heterogeneity in key properties such as luminescence efficiency and device performance. However, the origin of the variations remains a topic of debate, and a precise understanding is critical to the rational design of defect management strategies. Through a multi-scale investigation – combining correlative synchrotron scanning X-ray diffraction and time-resolved photoluminescence measurements on the same scan area – we reveal that lattice strain is directly associated with enhanced defect concentrations and non-radiative recombination. The strain patterns have a complex heterogeneity across multiple length scales. We propose that strain arises during the film growth and crystallization and provides a driving force for defect formation. Our work sheds new light on the presence and influence of structural defects in halide perovskites, revealing new pathways to manage defects and eliminate losses.

Scanning X-ray microdiffraction with submicrometer white beam for strain/stress and orientation mapping in thin films.

Abstract: Scanning X-ray microdiffraction (µSXRD) combines the use of high-brilliance synchrotron sources with the latest achromatic X-ray focusing optics and fast large-area two-dimensional-detector technology. Using white beams or a combination of white and monochromatic beams, this technique allows for the orientation and strain/stress mapping of polycrystalline thin films with submicrometer spatial resolution. The technique is described in detail as applied to the study of thin aluminium and copper blanket films and lines following electromigration testing and/or thermal cycling experiments. It is shown that there are significant orientation and strain/stress variations between grains and inside individual grains. A polycrystalline film when investigated at the granular (micrometer) level shows a highly mechanically inhomogeneous medium that allows insight into its mesoscopic properties. If the µSXRD data are averaged over a macroscopic range, results show good agreement with direct macroscopic texture and stress measurements.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

Pattern Recognition and Machine Learning

Abstract: Probability Distributions.- Linear Models for Regression.- Linear Models for Classification.- Neural Networks.- Kernel Methods.- Sparse Kernel Machines.- Graphical Models.- Mixture Models and EM.- Approximate Inference.- Sampling Methods.- Continuous Latent Variables.- Sequential Data.- Combining Models.

Fourier-transform method of fringe-pattern analysis for computer-based topography and interferometry

Abstract: A fast-Fourier-transform method of topography and interferometry is proposed. By computer processing of a noncontour type of fringe pattern, automatic discrimination is achieved between elevation and depression of the object or wave-front form, which has not been possible by the fringe-contour-generation techniques. The method has advantages over moire topography and conventional fringe-contour interferometry in both accuracy and sensitivity. Unlike fringe-scanning techniques, the method is easy to apply because it uses no moving components.