White matter alterations in neurodegenerative and vascular dementia

Die Zuordnung einer Demenzerkrankung zu einem neurodegenerativen Pathomechanismus, wie der Demenz vom Alzheimer-Typ (DAT), oder einem vaskulären Pathomechanismus, kann trotz der Verfügbarkeit bildgebender Verfahren Probleme bereiten. Überlappungen neurodegenerativer und vaskulärer Mechanismen sind häufig. Mikroangiopathische Veränderungen des Marklagers finden sich bei einem hohen Anteil von Patienten mit der klinischen Verlaufsform einer Demenz vom Alzheimer-Typ. Es ist unklar, ob es sich um eine Koinzidenz zweier Pathomechanismen handelt oder ob eine wechselseitige Beeinflussung stattfindet. Die hohe Sensitivität der Magnet-Resonanz-Tomographie bei der Erfassung von mikroangiopathischen Veränderungen des Marklagers könnte dazu führen, dass zu häufig vaskuläre Demenzerkrankungen diagnostiziert werden. Der Einfluss mikroangiopathischer Veränderungen des Marklagers auf den Demenzverlauf wird kontrovers diskutiert. Die vorgelegte Arbeit gibt eine Übersicht über die aktuellen Konzepte zum Stellenwert von Marklagerveränderungen bei Demenzerkrankungen.Due to a significant overlap of the two syndromes, differentiation of degenerative dementia of the Alzheimer-Type from vascular dementia may be difficult even when imaging studies are available. White matter changes occur in many patients suffering from Alzheimer\u27s disease. Little is known about the impact of white matter changes on the course and clinical presentation of Alzheimer\u27s disease. High sensitivity of MRI in the detection of white matter alterations may account for over-diagnosing vascular dementia. The clinical significance of white matter alterations in dementia is still a matter of debate. The article reviews current concepts about the role of white matter alterations in dementia

Porosity characterization and its effect on thermal properties of APS-sprayed alumina coatings

In the thermal spraying process, the porosity of ceramic coatings contributes directly to the efficiency of the thermal insulation. The size, shape, and distribution of the pores determine the level of both thermal and sintering resistance. In this work, three different atmospheric plasma sprayed (APS) alumina coatings were fabricated with the same spraying parameters using alumina powders with fine, medium, and coarse particle size. The microstructure of the obtained coatings was analyzed regarding the obtained total porosity, pore size, and pore shape. It was found that it is expedient to divide the pore size range into fine, medium, and large sizes. The shape was characterized with regard to the circularity aspect. In this way, all types of cracks can be considered as oblate pores and were included in the calculation of the total porosity. In the case of using fine feedstock powder, the densest coatings were produced among all coatings, and the fraction of fine pores and cracks are thereby substantially higher. However, the total porosity increases with increasing feedstock powder size. A connection was also made between thermal insulation and porosity fraction which includes fine pores and cracks

Combining thermal spraying and magnetron sputtering for the development of Ni/Ni-20Cr thin film thermocouples for plastic flat film extrusion processes

In the digitalization of production, temperature determination is playing an increasingly important role. Thermal spraying and magnetron sputtering were combined for the development of Ni/Ni-20Cr thin film thermocouples for plastic flat film extrusion processes. On the thermally sprayed insulation layer, AlN and BCN thin films were deposited and analyzed regarding their structural properties and the interaction between the plastic melt and the surfaces using Ball-on-Disc experiments and High-Pressure Capillary Rheometer. A modular tool, containing the deposited Ni/Ni-20Cr thin film thermocouple, was developed and analyzed in a real flat film extrusion process. When calibrating the thin film thermocouple, an accurate temperature determination of the flowing melt was achieved. Industrial type K sensors were used as reference. In addition, PP foils were produced without affecting the surface quality by using thin film thermocouples

Temperature-induced formation of lubricous oxides in vanadium containing iron-based arc sprayed coatings

In the field of surface engineering, the use of self-lubricous coatings with the incorporation of vanadium represent a promising approach to reduce friction, thus contributing to the wear behavior. For vanadium containing hard coatings produced by means of thin film technology, the reduction in friction at elevated temperatures was repeatedly attributed to temperature-induced and tribo-oxidatively formed oxides which act as solid lubricant. Only very few studies focused on the tribological characteristics of vanadium containing arc sprayed coatings. In this study, the tribological characteristics of a vanadium containing iron-based arc sprayed deposit were investigated in dry sliding experiments under ambient conditions and different temperatures. Types of wear at the worn surfaces and counterparts were examined by means of electron microscopy and energy dispersive X-ray (EDX) spectroscopy. The speciation of vanadium in the superficial layer was determined using X-ray absorption near edge structure (XANES) spectroscopy. It was found that the vanadium-containing coating exhibited a distinctly reduction of the coefficient of friction above 450 °C which further decreased with increasing temperature. XANES spectroscopy indicated an increased oxidation state for the V component on the coating surface, suggesting the prevalence of specific vanadium oxides which promote a self-lubricating ability of the coating

Fatigue and corrosion fatigue behaviour of brazed stainless steel joints AISI 304L/BAu-4 in synthetic exhaust gas condensate

As brazed stainless steel components in service often have to withstand cyclic loads in corrosive environments, the corrosion fatigue properties of brazed joints have to be characterised. Application-relevant corrosion fatigue tests in corrosive media are extremely rare for brazed joints and cyclic deformation curves are barely investigated. In this study, fatigue tests of brazed AISI 304L/BAu-4 joints were performed in air and synthetic exhaust gas condensate K2.2 according to VDA 230-214. The fatigue behaviour of the brazed joints was compared to properties of the austenitic base material. Strain, electrical, magnetic, temperature and electrochemical measurement techniques were applied within fatigue and corrosion fatigue tests to characterise the cyclic deformation and damage behaviour of the brazed joints. It was found that the fatigue strength of 397 MPa at 2 × 106 cycles was reduced down to 51% due to the superimposed corrosive loading. Divergent microstructure-related damage mechanisms were identified for corrosion fatigue loadings and fatigue loadings of specimens in the as-received and pre-corroded conditions. The investigations demonstrate the important role of corrosive environments for the mechanical performance of brazed stainless steel joints

Syntheses and Properties of Cycloamidines Based on 4H-Imidazoles*

Employing three different syntheses a broad spectrum of 4H-imidazoles 3a -3s has been synthesized. In the course of the two-fold aminolysis reaction leading to derivatives 3q -3s, deeply colored byproducts could be isolated and structural characterized.These novel donor-acceptor derivatives of type 7 consist of an 1H-and 4H-imidazole which are connected by a nitrogen bridge and rearrange via rapid 1,3-/1,5-hydride shifts. Using 1 H NMR experiments the aminolysis product 3p shows prototropic isomers which could be detected in equilibrium for the first time. Cyclovoltammetric measurements of a series of substituted 2-aryl derivatives 3d -3i displayed two reversible single electron transfer steps with relatively small semiquinone formation constants between 10 2 and 4 × 10 3 . The 4H-imidazole 3d was successfully converted into boratetraaza-pentalene 8a, which showed two well separated reduction potentials. The value of semiquinone formation constant of 8a (1.8 × 10 15 ) is even higher than those reported for similar derivatives. 4H-imidazoles can also be employed for the efficient complexation of catalytically important metals as exemplified by copper complexes 11 and 12. Derivative 3m, which possesses an additional chelating pyridine substructure, formed a stable complex of structural composition Zn(3m) 2 with diethyl zinc

Reduction of ejection forces in injection molding by applying mechanically post-treated CrN and CrAlN PVD films

In injection molding, the reduction of ejection forces is a process relevant aspect to improve the production rates. For this purpose, CrN and CrAlN films were sputtered on cylindrical and quadratic AISI H11 cores of an injection mold in order to investigate their influence on the resulting ejection forces to demold polypropylene test components. Within this context, the ejection forces of the PVD coated cores were compared to those of uncoated cores made of AISI H11. For both the cylindrical and quadratic cores, the as-deposited CrN and CrAlN films exhibit higher ejection forces than the uncoated cores due to the increase of the roughness profile after sputtering. It is known that the ejection forces are directly related to the surface roughness. In order to ensure comparable surface conditions to the uncoated surfaces, and to demonstrate the potential of PVD coated mold surfaces when reducing the ejection forces, the coated surfaces were mechanically post-treated to obtain a similar roughness profile as the uncoated cores. The combination of a PVD deposition and post-treatment ensures a significant reduction of the ejection forces by 22.6% and 23.7% for both core geometries

Anaerobic Microbial Degradation of Hydrocarbons: From Enzymatic Reactions to the Environment

Hydrocarbons are abundant in anoxic environments and pose biochemical challenges to their anaerobic degradation by microorganisms. Within the framework of the Priority Program 1319, investigations funded by the Deutsche Forschungsgemeinschaft on the anaerobic microbial degradation of hydrocarbons ranged from isolation and enrichment of hitherto unknown hydrocarbon-degrading anaerobic microorganisms, discovery of novel reactions, detailed studies of enzyme mechanisms and structures to process-oriented in situ studies. Selected highlights from this program are collected in this synopsis, with more detailed information provided by theme-focused reviews of the special topic issue on 'Anaerobic biodegradation of hydrocarbons' [this issue, pp. 1-244]. The interdisciplinary character of the program, involving microbiologists, biochemists, organic chemists and environmental scientists, is best exemplified by the studies on alkyl-/arylalkylsuccinate synthases. Here, research topics ranged from in-depth mechanistic studies of archetypical toluene-activating benzylsuccinate synthase, substrate-specific phylogenetic clustering of alkyl-/arylalkylsuccinate synthases (toluene plus xylenes, p-cymene, p-cresol, 2-methylnaphthalene, n-alkanes), stereochemical and co-metabolic insights into n-alkane-activating (methylalkyl) succinate synthases to the discovery of bacterial groups previously unknown to possess alkyl-/arylalkylsuccinate synthases by means of functional gene markers and in situ field studies enabled by state-of-the-art stable isotope probing and fractionation approaches. Other topics are Mo-cofactor-dependent dehydrogenases performing O-2-independent hydroxylation of hydrocarbons and alkyl side chains (ethylbenzene, p-cymene, cholesterol, n-hexadecane), degradation of p-alkylated benzoates and toluenes, glycyl radical-bearing 4-hydroxyphenylacetate decarboxylase, novel types of carboxylation reactions (for acetophenone, acetone, and potentially also benzene and naphthalene), W-cofactor-containing enzymes for reductive dearomatization of benzoyl-CoA (class II benzoyl-CoA reductase) in obligate anaerobes and addition of water to acetylene, fermentative formation of cyclohexanecarboxylate from benzoate, and methanogenic degradation of hydrocarbons

Identification of regulatory variants associated with genetic susceptibility to meningococcal disease.

Non-coding genetic variants play an important role in driving susceptibility to complex diseases but their characterization remains challenging. Here, we employed a novel approach to interrogate the genetic risk of such polymorphisms in a more systematic way by targeting specific regulatory regions relevant for the phenotype studied. We applied this method to meningococcal disease susceptibility, using the DNA binding pattern of RELA - a NF-kB subunit, master regulator of the response to infection - under bacterial stimuli in nasopharyngeal epithelial cells. We designed a custom panel to cover these RELA binding sites and used it for targeted sequencing in cases and controls. Variant calling and association analysis were performed followed by validation of candidate polymorphisms by genotyping in three independent cohorts. We identified two new polymorphisms, rs4823231 and rs11913168, showing signs of association with meningococcal disease susceptibility. In addition, using our genomic data as well as publicly available resources, we found evidences for these SNPs to have potential regulatory effects on ATXN10 and LIF genes respectively. The variants and related candidate genes are relevant for infectious diseases and may have important contribution for meningococcal disease pathology. Finally, we described a novel genetic association approach that could be applied to other phenotypes