Comparison of fresh and aged lithium iron phosphate cathodes using a tailored electrochemical strain microscopy technique

Electrochemical strain microscopy (ESM) is a powerful atomic force microscopy (AFM) mode for the investigation of ion dynamics and activities in energy storage materials. Here we compare the changes in commercial LiFePO4 cathodes due to ageing and its influence on the measured ESM signal. Additionally, the ESM signal dynamics are analysed to generate characteristic time constants of the diffusion process, induced by a dc-voltage pulse, which changes the ionic concentration in the material volume under the AFM tip. The ageing of the cathode is found to be governed by a decrease of the electrochemical activity and the loss of available lithium for cycling, which can be stored in the cathode.

Sub-femtosecond hard X-ray radiation generated by electron bunches ejected from water jet

A new two-step approach for frequency conversion of laser radiation towards hard X-rays is developed and examined experimentally. Fast electrons are produced in a form of thin jets at the first stage, as an intense femtosecond laser pulses impinges on a micrometer water target. In the second stage the accelerated electrons hit a secondary metal target and generate characteristic K-shell radiation with a duration down to sub-femtosecond. It is shown that counter propagating laser radiation experiences very strong up-shift with up to 6 × 103 times of fundamental frequency by reflection from the electron jets.

MRI Texture Analysis in Multiple Sclerosis

Multiple sclerosis (MS) is a complicated disease characterized by heterogeneous pathology that varies across individuals. Accurate identification and quantification of pathological changes may facilitate a better understanding of disease pathogenesis and progression and help identify novel therapies for MS patients. Texture analysis evaluates interpixel relationships that generate characteristic organizational patterns in an image, many of which are beyond the ability of visual perception. Given its promise detecting subtle structural alterations texture analysis may be an attractive means to evaluate disease activity and evolution. It may also become a new tool to assess therapeutic efficacy if technique issues are resolved and pathological correlates are further confirmed. This paper describes the concept, strategies, and considerations of MRI texture analysis; summarizes applications of texture analysis in MS as a measure of tissue integrity and its clinical relevance; then discusses potentially future directions of texture analysis in MS.

Use of a Single, Triplicate Arbitrarily Primed-PCR Procedure for Molecular Fingerprinting of Lactic Acid Bacteria

ABSTRACT Arbitrarily primed (AP)-PCR can be used to generate characteristic DNA fingerprint patterns. However, small changes in reaction conditions can cause band irreproducibility. In this study, a single methodology encompassing triplicate reactions, which were intentionally exposed to three different annealing temperatures, enabled bands that were reproducibly generated to be recognized. A single triplicate AP-PCR (TAP-PCR) procedure, using an 18-mer primer, was developed and used to fingerprint representative isolates from the major genera of lactic acid bacteria and Bifidobacterium to the strain level.

Characteristic Measures for the Representation of Manufactured Surface Quality

In this paper, we investigate four methods that yield mathematical measures to analyze the precision of surfaces of manufactured parts. These four methods, namely the autocorrelation function, the Fourier spectrum, the Karhunen-Loève expansion, and a fractal-wavelet representation, are applied to surfaces produced from grinding processes. The first two methods are standard methods used in the surface analysis literature for qualitative signal characterization. The Karhunen-Loève expansion method, used in various signal processing applications, has never been applied to the field of surface characterization and representation. The fractal-wavelet representation has been previously proposed by the authors; its suitability to generate characteristic measures is investigated in this paper. The existence of characteristic measures of surface precision should aid designers in choosing process and design parameters and in comparing the precision between competing machining processes. The use of such measures is essential in taking a forward step towards integrating the fields of design and manufacturing.

Origins of the Gap States in Polycrystalline Silicon: Tight-Binding Calculations of Twist Boundaries

ABSTRACTThe atomic and electronic structures of the twist boundaries Σ (=3 (011), Σ=7 (111) and Σ=5 (001)) in Si have been calculated by using the transferable SETB method coupled with the supercell technique. The twist boundaries in Si contain larger structural disorder or more defects and larger interfacial energies than tilt grain boundaries. Several kinds of structural disorder or defects have been found to generate characteristic electronic states inside the gap. The present structural disorder or defects and the gap states are the candidates of the origins of the observed band-tails or mid-gap states in polycrystalline Si as well as those In amorphous Si.