Multiple factors contribute to the peripheral induction of cerebral beta-amyloidosis

Contains fulltext : 135971.pdf (publisher's version ) (Open Access)Deposition of aggregated amyloid-beta (Abeta) peptide in brain is an early event and hallmark pathology of Alzheimer's disease and cerebral Abeta angiopathy. Experimental evidence supports the concept that Abeta multimers can act as seeds and structurally corrupt other Abeta peptides by a self-propagating mechanism. Here we compare the induction of cerebral beta-amyloidosis by intraperitoneal applications of Abeta-containing brain extracts in three Abeta-precursor protein (APP) transgenic mouse lines that differ in levels of transgene expression in brain and periphery (APP23 mice, APP23 mice lacking murine APP, and R1.40 mice). Results revealed that beta-amyloidosis induction, which could be blocked with an anti-Abeta antibody, was dependent on the amount of inoculated brain extract and on the level of APP/Abeta expression in the brain but not in the periphery. The induced Abeta deposits in brain occurred in a characteristic pattern consistent with the entry of Abeta seeds at multiple brain locations. Intraperitoneally injected Abeta could be detected in blood monocytes and some peripheral tissues (liver, spleen) up to 30 d after the injection but escaped histological and biochemical detection thereafter. These results suggest that intraperitoneally inoculated Abeta seeds are transported from the periphery to the brain in which corruptive templating of host Abeta occurs at multiple sites, most efficiently in regions with high availability of soluble Abeta

Tissue phase affected fracture toughness of nano-columnar TiB2 + z thin films

Structural imperfections such as nano-columnar tissue phases constitute a morphological design feature in protective thin films. Especially in the rising group of PVD transition metal diborides, excess Boron is known to form nm-sized B-rich precipitations in-between nano-crystalline domains. Here, we focus on super-stoichiometric TiB2 + z thin films, varying the stoichiometry from TiB2.04 to TiB4.42 (B: 67–82 at.%). The tissue phase fraction and thickness is mainly governed by the B content and corresponding deposition conditions. A decreasing tissue phase width from ≈ 3–1 nm leads to an increasing critical stress intensity factor KIC of ≈ 40%

Anisotropic super-hardness of hexagonal WB2±z_{2±z} thin films

Transition metal diboride-based thin films are promising candidates to replace state-of-the-art protective and functional coating materials due to their unique properties. Here, we focus on hexagonal WB$_{2-z}$, showing that the AlB2 structure is stabilized by B vacancies exhibiting its energetic minima at sub-stoichiometric WB$_{1.5}$. Nanoindentation reveals super-hardness of 0001 oriented $α$-WB$_{2-z}$ coatings, linearly decreasing by more than 15 GPa with predominant $10\bar{1}1$ orientation. This anisotropy is attributed to differences in the generalized stacking fault energy of basal and pyramidal slip systems, highlighting the feasibility of tuning mechanical properties by crystallographic orientation relations

Influence of Ta on the oxidation resistance of WB2-z coatings

Ternary W1-x TaxB2-z is a promising protective coating material possessing enhanced ductile character and phase stability compared to closely related binaries. Here, the oxidation resistance of W1-xTaxB2-z thin films was experimentally investigated at temperatures up to 700 degrees C. Ta alloying in sputter deposited WB2-z coatings led to decelerated oxide scale growth and a changed growth mode from paralinear to a more linear (but retarded) behavior with increasing Ta content. The corresponding rate constants decrease from k(p)* = 6.3.10(-4) mu m(2)/s for WB2-z to k(p)* = 1.1.10(-4) mu m(2)/s for W0.66Ta0.34B2-z as well as k(1) = 2.6.10(-5) mu m/s for TaB2-z, underlined by decreasing scale thicknesses ranging from 1170 nm (WB2-z), over 610 nm (W0.66Ta0.34B2-z) to 320 nm (TaB2-z) after 10 min at 700 degrees C. Dense and adherent scales exhibit an increased tantalum content (columnar oxides), which suppresses the volatile character of tungsten-rich as well as boron oxides, hence being a key-factor for enhanced oxidation resistance. Thus, adding Ta (in the range of x = 0.2-0.3) to a-structured WB2-z does not only positively influence the ductile character and thermal stability but also drastically increases the oxidation resistance

Stability of the derivative of a canonical product

With each sequence α=(αn)n∈N of pairwise distinct and non-zero points which are such that the canonical product   Pα(z):=limr→∞∏∣αn∣≤r(1−z/αn) converges, the sequence   α′:=(Pα'(αn))n∈N is associated. We give conditions on the difference β−α of two sequences which ensure that β' and α' are comparable in the sense that   ∃c,C>0: c|α'n|≤|β'n|≤C|α'n|,  n∈N. The values α'n play an important role in various contexts. As a selection of applications we present: an inverse spectral problem, a class of entire functions and a continuation problem