Search

Tribological loading of metals induces microstructural changes by dislocation-mediated plastic deformation. During continued sliding, combined shear and lattice rotation result in the formation of crystallographic textures which influence friction and wear at the sliding interface. In order to elucidate the fundamental lattice rotation kinematics involved in this process during the early stages of sliding, we conducted unlubricated, linear single pass sliding experiments on a copper bicrystal using sapphire spheres. Electron backscatter diffraction (EBSD) performed directly on the bulk surface of the wear tracks in the vicinity of the grain boundary reveals crystal lattice rotations by approximately up to 35°. Predominantly, the tribologically induced crystal rotations appear to be kinematically constrained to rotations around the transverse direction (TD) and occur in both grains, irrespective of load (2 to 8 N). We demonstrate that inverting the sliding direction (SD) inverts the sense of crystal rotation, but does not change the principal nature of rotation for the majority of indexed EBSD data. A lower proportion of the crystal lattice rotates much farther around TD (roughly up to 90°), accompanied by a superimposed crystal rotation around ±SD. Analysis reveals that sliding direction and grain orientation exert a systematic influence of how crystal rotations are accommodated. This is rationalized in terms of geometry, anisotropic wear track profiles and slip traces. Under specific conditions, combined crystal rotation and twinning are observed. These detailed insights into the fundamental nature of tribologically induced lattice rotation kinematics provide important guidance for applied research targeting materials with superior tribological properties. [Display omitted] [ABSTRACT FROM AUTHOR]

We present a technique for extracting 3D information from small-scale fossil and Recent material and give a summary of other contemporary techniques for 3D methods of investigation. The only hardware needed for the here-presented technique is a microscope that can perform dark field and/or differential interference contrast with a mounted digital camera and a computer. Serial images are taken while the focus is successively shifted from the uppermost end of the specimen to the lowermost end, resulting in about 200 photographs. The data are then processed almost completely automatically by successive use of three freely available programs. Firstly, the stack of images is aligned by the use ofCombineZM, which is used to produce a combined image with a high depth of field. Secondly, the aligned images are cropped and sharp edges extracted with the aid ofImageJ. Thirdly, althoughImageJ is also capable of producing 3D representations, we preferred to process the image stack further usingosirix as it has the facility to export various formats. One of the interesting export formats is a virtual Quicktime movie file (QTVR), which can be used for documentation, and stereo images can also be produced from this Quicktime VR. This method is easy to apply and can be used for documenting specimens in 3D (at least some aspects) without having to prepare them. Therefore, it is particularly useful as a safe method for documenting limited material, before using methods that may destroy the specimen of interest, or to investigate type material that cannot be treated with any preparatory technique. As light microscopes are available in most labs and free computer programs are easily accessible, this method can be readily applied. [ABSTRACT FROM AUTHOR]

Examines the incorporation of nitrogen in homoepitaxial chemical vapor deposition diamond films. Application of nuclear reaction analysis; Details on the N/C ratios of the films; Addition of 50 ppm of isotopic nitrogen to the process gas.

The basic mechanisms of defect formation due to ion bombardment during bias assisted growth of diamond films were studied. Diamond films were deposited at bias voltages between −60 and –120 V for 2 h on Ib single crystals. In ion channelling experiments a steep increase in dechannelling was found: For the film grown at the lowest bias voltage of –60 V dechannelling increased by a factor of 2 as compared to the 0-V reference film. For the subsequent sample, deposited at –80 V, channelling was already completely suppressed. Analysis of backscatter Kikuchi patterns indicates that up to –85 V the decrease in pattern contrast is caused by defects in the crystal lattice equally distributed over the film rather than by variations of the crystal lattice orientation (mosaicity). According to the Raman spectra three different regimes can be distinguished: At low bias voltages up to –60 V, signal from non-diamond carbon phases is negligible. At high bias voltages of –100 V and above, the typical signature of amorphous and graphitic carbon phases is found in the spectra. In the third regime at approximately –80 V, these spectral features exhibit pronounced fine structure and a strong enhancement in intensity. Our experiments suggest that luminescence as well as resonance Raman effects contribute to the form of these spectra. [Copyright &y& Elsevier]

Cells and tissues form the bewildering diversity of crustacean larval organ systems which are necessary for these organisms to autonomously survive in the plankton. For the developmental biologist, decapod crustaceans provide the fascinating opportunity to analyse how the adult organism unfolds from organ Anlagen compressed into a miniature larva in the sub-millimetre range. This publication is the second part of our survey of methods to study organogenesis in decapod crustacean larvae. In a companion paper, we have already described the techniques for culturing larvae in the laboratory and dissecting and chemically fixing their tissues for histological analyses. Here, we review various classical and more modern imaging techniques suitable for analyses of eidonomy, anatomy, and morphogenetic changes within decapod larval development, and protocols including many tips and tricks for successful research are provided. The methods cover reflected-light-based methods, autofluorescence-based imaging, scanning electron microscopy, usage of specific fluorescence markers, classical histology (paraffin, semithin and ultrathin sectioning combined with light and electron microscopy), X-ray microscopy (µCT), immunohistochemistry and usage of in vivo markers. For each method, we report our personal experience and give estimations of the method's research possibilities, the effort needed, costs and provide an outlook for future directions of research. [ABSTRACT FROM AUTHOR]

The radio-frequency plasma-assisted molecular beam epitaxy of cubic Al[sub y]Ga[sub 1-y]N/GaN heterostructures on GaAs(001) substrates is reported. Rutherford backscattering spectroscopy, high resolution x-ray diffraction, and first-order micro-Raman spectroscopy measurements were used to characterize the structural and vibrational properties of the alloy epilayers. The Al content of the alloy is in the range from 0.07

Background/Question Long-term potentiation (LTP) and long-term depression (LTD) are forms of cortical plasticity and are considered to be synaptic processes underlying learning and memory. Patterned transcranial magnetic stimulation (TMS) such as theta burst stimulation (TBS) or quadri-pulse stimulation (QPS) can induce LTP-like and LTD-like effects in human primary motor cortex (M1), displayed by an increase or decrease in cortico-spinal excitability. Here, we aimed to test the plasticity-inducing capabilities of a novel protocol that merged TBS and QPS – so called quadri-pulse theta burst stimulation (qTBS) – at interstimulus intervals (ISI) that mimic I-wave periodicity (i.e. 1.5 ms/666 Hz) with an effective anterior-posterior (AP) and posterior-anterior (PA) current flow in the brain. Methods We investigated healthy volunteers ( n = 12 per protocol) with 360 bursts of qTBS that was continuously given to M1 (i.e. 1440 full-sine pulses). QTBS consisted of repeated bursts of four biphasic TMS pulses (duration: 160 μ s) separated by ISI of 1.5 ms (666 Hz) and inter-burst intervals of 200 ms. (5 Hz). TMS was applied by a custom-made magnetic stimulator (IMETUM, Munich). Resting motor threshold (rMT), and motor evoked potential (MEP) amplitudes with stimulus intensities to target amplitudes of 1mv (SI1mV) were measured before (Pre) qTBS, directly after (Post1), after 15 min (Post2), after 30 min (Post3) and after 60 min (Post4). Results PA-qTBS at 666 Hz caused a decrease in mean MEP amplitudes, whereas AP-qTBS at 666 Hz induced an increase in mean MEP amplitudes outlasting for approximately 60 min. As expected, baseline data of rMT prior to qTBS differed significantly, with higher thresholds in AP direction. Discussion/Conclusion Continuous qTBS at 666 Hz can induce lasting changes in cortico-spinal excitability. Induced current direction in the brain appears to be relevant when qTBS targets I-wave periodicity, corroborating that high-fidelity spike timing mechanisms are critical for inducing bi-directional plasticity in human M1. [ABSTRACT FROM AUTHOR]

Aims: The limitations of the current WHO classification of astrocytomas call for a sustained effort to improve diagnostic and prognostic accuracy. The relationship between tumour growth and clinical outcome suggests that proliferative activity should be examined. The objective of this study was to evaluate the diagnostic and prognostic value of the proliferation markers mitosin and phosphohistone H3 (pHH3) in infiltrative astrocytomas WHO grades II and III and compare the findings with mitotic count and Ki-67/MiB-1 immunostaining.Methods: Fifty-nine and thirty-three infiltrative astrocytomas WHO grades II and III, respectively, were immunostained with the proliferation markers mitosin and pHH3 using standard immunohistochemical procedures. The expression was quantified as a proliferative index (PI) and statistically evaluated with Spearman's rank correlation test, Wilcoxon-Mann-Whitney U test, and univariable and multivariable COX regression survival analyses.Results: Significant positive correlations were found between these proliferation markers. The number of mitoses, pHH3 mitotic figures (MFs), the Ki-67/MiB-1 PI and the mitosin PI were greater in WHOgrade III anaplastic astrocytomas compared to WHO grade II diffuse astrocytomas, while pHH3 PI only showed a trend. All proliferation markers were associated with poorer prognosis, but mitotic count was not. Ki-67/MiB-1, mitosin and pHH3 MF achieved statistical significance in the univariable analyses of both time to relapse (TTR) and overall survival (OS). Only mitosin remained significant in both multivariable analyses. pHH3 was significant in the multivariable analysis of OS but not of TTR. Clinical factors including age, extent of surgical resection and WHO performance status were also significantly correlated with survival.Conclusions: In conclusion, mitosin and pHH3 immunostaining have prognostic and diagnostic value in the clinical assessment of patients with infiltrative astrocytomas. The inclusion of proliferation markers in a layered diagnosis should be considered in the upcoming revision of the WHO classification system. [ABSTRACT FROM AUTHOR]

Abstract Background: Insulin pump systems now provide automated bolus calculators (ABCs) that electronically calculate insulin boluses to address carbohydrate intake and out-of-range blood glucose (bG) levels. We compared the efficacy of three ABCs (Accu-Chek((R)) Combo [Roche Insulin Delivery Systems (IDS), Inc., Fishers, IN, a member of the Roche Group], Animas((R)) 2020 [Animas Corp., West Chester, PA, a Johnson and Johnson company], and MiniMed Paradigm Bolus Wizard((R)) [Medtronic MiniMed, Northridge, CA]) to safely reduce postprandial hyperglycemia in type 1 diabetes mellitus (T1DM). Methods: T1DM subjects (n = 24) were recruited at a single center for a prospective, triple crossover study. ABCs with the programmed target range (80-140 mg/dL) were used in random order. Postprandial hyperglycemia was induced by reducing the calculated bolus by 25%. Two hours after test meals, the ABCs were allowed to determine whether a correction bolus was needed. Differences between 6-h bG values after test meals that achieved 2-h postprandial hyperglycemia and the mean of the target range (110 mg/dL) were determined. Results: The mean difference between 6-h bG levels following test meals and the 110 mg/dL bG target with the MiniMed device (47.4 ± 31.8 mg/dL) was significantly higher than the Animas (17.3 ± 30.9 mg/dL) and Roche IDS (18.8 ± 33.8 mg/dL) devices (P = 0.0022 and P = 0.0049, respectively). The number of meals with 2-h postprandial hyperglycemia and bG levels at 2 h was similar. Roche IDS and Animas devices recommended correction boluses significantly (P = 0.0001 and P = 0.0002, respectively) more frequently than the MiniMed device. ABC use was not associated with severe hypoglycemia. There was no significant difference in the rate of mild hypoglycemia (bG <60 mg/dL not requiring assistance) among the three groups (Roche IDS and Animas, n = 2; MiniMed, n = 0). Conclusions: In this study, the Roche IDS and Animas devices were more efficacious in controlling postprandial hyperglycemia than the MiniMed device. This may be due, in part, to differences in ABC setup protocols and algorithms. Use of ABCs can assist in controlling postprandial glycemia without significant hypoglycemia. [ABSTRACT FROM AUTHOR]

Background: The primary objective of this study was to investigate the difference in the proportion of patients with conventionally detected hypoglycemia compared with continuous glucose monitoring system (CGMS((R)), Medtronic MiniMed((R)), Sylmar, CA)-detected glucose values

In 12 patients with primary hypogammaglobulinaemia we investigated the in vivo effect of one bolus injection (400 mg/kg) of intravenous immunoglobulin (IVIG) on lymphocyte subsets and monocytes in peripheral blood, on plasma levels of soluble factors reflecting monocyte and lymphocyte activity and on lymphocyte proliferation and generation of reactive oxygen species (ROS) from monocytes analysed in vitro. Several immunological changes were induced by IVIG infusion. First, there was a significant decrease in CD4+/CD8+ lymphocyte ratio in peripheral blood, reflecting a significant increase in circulating numbers of CD8+ lymphocytes. Second, although there was no significant change in plasma levels of soluble CD8 antigen, there was a significant decrease in soluble CD8 antigen/CD8+ lymphocyte ratio, suggesting a down-regulation of CD8+ lymphocyte activity. Third, there was a significant increase in plasma levels of neopterin, suggesting in vivo activation of monocytes/ macrophages. Fourth, the was a down-modulation of mitogen-stimulated lymphocyte proliferation in vitro, and this down-regulation was significantly correlated with the increase in plasma neopterin levels. Finally, there was a significant decrease in zymosan-stimulated, but not in phorbol myristate acetate-stimulated, ROS generation from monocytes as evaluated by nitroblue tetrazolium reduction. The ability of IVIG administration in vivo to down-modulate lymphocyte proliferation and ROS generation from monocytes in patients with persistent immune activation may be relevant for the clinical effects of IVIG in a variety of immune-mediated disorders. [ABSTRACT FROM AUTHOR]

Question: Long-term potentiation (LTP) and long-term depression (LTD) are forms of cortical plasticity and are considered to be synaptic processes underlying learning and memory. Transcranial magnetic stimulation (TMS) with monophasic quadro-pulses (QPS) demonstrated to be effective to induce LTD-and LTP-like plasticity in human motor cortex (M1). Here, we aimed to study whether biphasic QPS at different inter-stimulus-and inter-burst-intervals induces plastic changes in human M1. Methods: We investigated healthy volunteers (n =10 per protocol) with quadro-pulse stimulation (QPS) consisting of repeated bursts of four biphasic TMS pulses (duration: 160μs) separated by inter-stimulus intervals of 1.5ms and 50ms and inter-burst intervals of 200ms, 1s and 5s resulting in 6 different protocols (QPS1.5−200, QPS1.5−1, QPS1.5−5, QPS50−200, QPS50−1, QPS50−5; 1440 total stimulus counts per protocol). TMS was applied by a custom-made magnetic stimulator (IMETUM, Munich). Resting motor threshold (rMT), and motor evoked potential (MEP) amplitudes with stimulus intensities to target amplitudes of 1mv and 0.4mV (SI1mV and SI0.4mV) were measured before (Pre) QPS directly after (Post1), after 15min (Post2), after 30min (Post3) and after 60min (Post4). Results: We found a significant increase of MEPs after QPS1.5−5 at SI0.4mV and a significant decrease after QPS50−200, QPS50−5 and QPS1.5−200 at SI1 mV. QPS1.5−1 and QPS50−1 had no significant effect on MEPs, respectively. Significant changes in rMT, referring to a model of intrinsic plasticity, were observed for QPS50−200 but not for QPS50−5. Conclusion: Biphasic QPS demonstrated to induce intensity and frequency dependent LTP-or LTD-like effects displayed by an increase or decrease in MEP amplitudes. This form of stimulation might offer new opportunities in investigations of cortical plasticity in humans. [Copyright &y& Elsevier]