Electron Microscopy and Analysis deals with several sophisticated techniques for magnifying images of very small objects by large amounts - especially in a physical science context. It has been ten ...years since the last edition of Electron Microscopy and Analysis was published and there have been rapid changes in this field since then. The authors have vastly updated their very successful second edition, which is already established as an essential laboratory manual worldwide, and they have incorporated questions and answers in each chapter for ease of learning. Equally as relevant for material scientists and bioscientists, this third edition is an essential textbook.
The interactions between oppositely charged surfactant/polymer mixtures have been studied using neutron reflectometry with supplementary surface tension measurements. The cationic surfactant dodecyl ...trimethylammonium bromide (C12TAB)/anionic polyelectrolyte sodium poly(styrene sulfonate) (NaPSS) system is compared with a system containing anionic sodium dodecyl sulfate (SDS) and cationic poly(vinyl pyridinium chloride) (PVPmCl). The PVPmCl/SDS mixture has been studied both with and without added electrolyte. Neutron reflection shows that for both systems, the surface consists of a mixture of polyelectrolyte and surfactant over a range of surfactant concentrations from above the critical micelle concentration (CMC) to CMC/100 for polymer concentrations between 10 and 140 ppm. In the lower surfactant concentration range, the amount of surfactant adsorbed approximately corresponds to a surfactant monolayer (area per molecule ∼ 35−45 Å 2 for SDS in the presence of 0.1 M NaCl, 35−60 Å2 without NaCl, and 50−60 Å2 for C12TAB with 0.1 M NaBr). However, at higher concentrations and in the presence of electrolyte, this increases to an amount approximately corresponding to three adsorbed layers (area per molecule = 12 Å2 for SDS and 17−20 Å2 for C12TAB). This increase is not observed for PVPmCl/SDS in the absence of 0.1 M NaCl. The structure of the higher concentration layer is a sandwich structure with an outer surfactant layer and a submerged polymer/micellar (spheres or rods) or polymer/defective bilayer. The surface tension and neutron results can be interpreted qualitatively in terms of three species in the system, a surface active complex PSS, a bilayer complex , which can only adsorb on a preformed PSS layer, and a bulk solution complex PSM. PSS is adsorbed at very low concentrations of surfactant, possibly even before any PSM is formed in the bulk solution. At high concentrations, there are two effects. There may be adsorption of complexes to the layer of PSS already at the surface. However, the formation of is in competition with the formation of PSM. If the latter is dominant, there is no secondary adsorption of , as is the case for PVPmCl/SDS in the absence of electrolyte, and the surface tension may increase very sharply with surfactant concentation at the point where the formation of PSM in the bulk solution is complete. If there is secondary adsorption of PSM or PSS, as for NaPSS/C12TAB with or without electrolyte and PVPmCl/SDS with electrolyte, the surface tension should show a more modest increase at this concentration.
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The first high-confinement mode (H-mode) with type-III edge localized modes at an
H
factor of
H
IPB98(
y
,2)
∼ 1 has been obtained with about 1 MW lower hybrid wave power on the EAST superconducting ...tokamak. The first H-mode plasma appeared after wall conditioning by lithium (Li) evaporation before plasma breakdown and the real-time injection of fine Li powder into the plasma edge. The threshold power for H-mode access follows the international tokamak scaling even in the low density range and a threshold in density has been identified. With increasing accumulation of deposited Li the H-mode duration was gradually extended up to 3.6 s corresponding to ∼30 confinement times, limited only by currently attainable durations of the plasma current flat top. Finally, it was observed that neutral density near the lower X-point was progressively reduced by a factor of 4 with increasing Li accumulation, which is considered the main mechanism for the H-mode power threshold reduction by the Li wall coatings.
The tetrahydronaphthalene−benzoxazine glucocorticoid receptor (GR) partial agonist 4b was optimized to produce potent full agonists of GR. Aromatic ring substitution of the tetrahydronaphthalene ...leads to weak GR antagonists. Discovery of an “agonist trigger” substituent on the saturated ring of the tetrahydronaphthalene leads to increased potency and efficacious GR agonism. These compounds are efficacy selective in an NFkB GR agonist assay (representing transrepression effects) over an MMTV GR agonist assay (representing transactivation effects). 52 and 60 have NFkB pIC50 = 8.92 (105%) and 8.69 (92%) and MMTV pEC50 = 8.20 (47%) and 7.75 (39%), respectively. The impact of the trigger substituent on agonism is modeled within GR and discussed. 36, 52, and 60 have anti-inflammatory activity in a mouse model of inflammation after topical dosing with 52 and 60, having an effect similar to that of dexamethasone. The original lead was discovered by a manual agreement docking method, and automation of this method is also described.
Polygenic risk scores (PRS) for breast cancer can be used to stratify the population into groups at substantially different levels of risk. Combining PRS and environmental risk factors will improve ...risk prediction; however, integrating PRS into risk prediction models requires evaluation of their joint association with known environmental risk factors.
Analyses were based on data from 20 studies; datasets analysed ranged from 3453 to 23 104 invasive breast cancer cases and similar numbers of controls, depending on the analysed environmental risk factor. We evaluated joint associations of a 77-single nucleotide polymorphism (SNP) PRS with reproductive history, alcohol consumption, menopausal hormone therapy (MHT), height and body mass index (BMI). We tested the null hypothesis of multiplicative joint associations for PRS and each of the environmental factors, and performed global and tail-based goodness-of-fit tests in logistic regression models. The outcomes were breast cancer overall and by estrogen receptor (ER) status.
The strongest evidence for a non-multiplicative joint associations with the 77-SNP PRS was for alcohol consumption (P-interaction = 0.009), adult height (P-interaction = 0.025) and current use of combined MHT (P-interaction = 0.038) in ER-positive disease. Risk associations for these factors by percentiles of PRS did not follow a clear dose-response. In addition, global and tail-based goodness of fit tests showed little evidence for departures from a multiplicative risk model, with alcohol consumption showing the strongest evidence for ER-positive disease (P = 0.013 for global and 0.18 for tail-based tests).
The combined effects of the 77-SNP PRS and environmental risk factors for breast cancer are generally well described by a multiplicative model. Larger studies are required to confirm possible departures from the multiplicative model for individual risk factors, and assess models specific for ER-negative disease.
Optimising the angular resolution of EBSD Brough, I.; Bate, P. S.; Humphreys, F. J.
Materials science and technology,
11/1/2006, 20061100, 2006-11-00, 20061101, Volume:
22, Issue:
11
Journal Article
Peer reviewed
The factors which determine the angular resolution in electron backscatter diffraction (EBSD), and the operating conditions which optimise it are considered. On suitable samples the angular ...resolution may be substantially improved by data averaging using an edge preserving Kuwahara filter. It is shown that measurements of misorientation by direct comparison of diffraction patterns can reduce the angular resolution to below 0·02°, and the application of this method to linescans and EBSD maps is discussed. It is concluded that the applicability of pattern comparison methods for EBSD maps is limited by time and microstructural considerations, but linescans using this method are shown to produce high quality data in material containing small misorientations, which cannot readily be analysed by the conventional Hough transform EBSD method.
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This textbook is an introduction to algebra via examples. The book moves from properties of integers, through other examples, to the beginnings of group theory. Applications to public key codes and ...to error correcting codes are emphasised. These applications, together with sections on logic and finite state machines, make the text suitable for students of computer science as well as mathematics students. Attention is paid to historical development of the mathematical ideas. This second edition contains new material on mathematical reasoning skills and a new chapter on polynomials has been added. The book was developed from first-level courses taught in the UK and USA. These courses proved successful in developing not only a theoretical understanding but also algorithmic skills. This book can be used at a wide range of levels: it is suitable for first- or second-level university students, and could be used as enrichment material for upper-level school students.
Fine-grained alloys by thermomechanical processing Humphreys, F.John; Prangnell, Philip B.; Priestner, Ronald
Current opinion in solid state & materials science,
2001, 2001-1-00, 20010101, Volume:
5, Issue:
1
Journal Article
Peer reviewed
Grain refinement during thermomechanical processing is conventionally achieved by discontinuous recrystallization. However, techniques involving severe deformation which increase the grain boundary ...area and can result in a micron-scale grain size by a process of continuous recrystallization have been developed. Various methods which are based on control of the deformation conditions and cooling rate during hot rolling of steels have utilised the
α–
γ phase transformation to produce micron-grained ferrite. Ultra-fine-grain structures exhibit interesting mechanical properties, and in certain cases a large amount of strengthening may be achieved with little or no reduction in ductility.
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The effect of hot deformation on fully recrystallized aluminium-copper alloys (Al-4wt%Cu and Al-33wt%Cu) with different volume fractions of CuAl₂ has been studied. The alloys are Zener pinned systems ...with different superplastic properties. Strain-induced grain growth, observed in both alloys, was quantitatively estimated by means of electron microscopy and EBSD and compared with the rate of static grain growth. Surface marker observations and in situ hot-deformation experiments combined with EBSD were aimed at clarifying the mechanisms responsible for the changes in the deformed microstructures. A sequence of secondary and backscattered electron images and EBSD maps was obtained during in situ SEM deformation with different testing conditions. Overlaying EBSD maps for the Al-4wt%Cu with channelling contrast images showed that grain boundary motion occurred during deformation, creating a layered structure and leading to an increase in size of some grains and shrinkage of others. Of a particular interest are results related to behaviour of CuAl₂ in superplastic Al-33wt%Cu during deformation, including several problems with the use of EBSD in this alloy.
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