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Total 154 results found since Jan 2013.

Study on the effects of forming conditions on microstructural evolution and forming behaviors of Cr-V-Mo tool steel during multi-stage thixoforging by physical simulation
In this study, a multi-stage thixoforging strategy including a partial melting, a fast first compression, a partial solidification, and a secondary compression was proposed to weaken phase segregation of thixoformed samples. A physical simulation of multi-stage thixoforging was conducted on commercial rolled Cr-V-Mo tool steel SKD11, using a multistage hot compression test machine. The microstructural evolution and forming behaviors of the SKD11 steel slurries in different stages of multi-stage thixoforging with various forming parameters were investigated experimentally. Out flow of liquid phase does not occur throughout ...
Source: Journal of Materials Processing Technology - June 6, 2017 Category: Materials Science Source Type: research

A combined numerical and experimental approach for determining the contact temperature in an industrial ironing operation
Publication date: Available online 15 September 2018Source: Journal of Materials Processing TechnologyAuthor(s): Esmeray Üstünyagiz, Chris V. Nielsen, Peter Christiansen, Paulo A.F. Martins, Taylan Altan, Niels BayAbstractTribological conditions in forming operations depend on several parameters such as tool-workpiece interface pressure, surface expansion, sliding length, sliding speed, tool and workpiece materials and the roughness of the parts. Among indirect parameters, the most influential one is the tool-workpiece interface temperature, which directly influences the lubricant performance. Prior to testing new tribo-...
Source: Journal of Materials Processing Technology - September 15, 2018 Category: Materials Science Source Type: research

Design and evaluation of a biosynthesized cellulose drug releasing duraplasty
In this study, a novel biosynthesized cellulose (BC)-based drug releasing duraplasty was developed and studied. The BC duraplasty fabrication process allowed readily incorporation of growth factors (GFs) in a sterile manner and control of physical and mechanical properties of the resulting duraplasty. Our results showed that BC duraplasty containing the highest amount of dry cellulose presented swelling ratio of 496 ± 27%, Young's modulus of 0.37 ± 0.02 MPa, ultimate tensile strength of 0.96 ± 0.02 MPa, while releasing GFs for over 10 days. In addition, neural stem/progenitor cell (NSPC) cultures demonstrated t...
Source: Materials Science and Engineering: C - January 28, 2020 Category: Materials Science Source Type: research

Is the optimal Tmax threshold identifying perfusion deficit volumes variable across MR perfusion software packages? A pilot study
ConclusionsThe optimal Tmax threshold for defining the ischemic penumbra appeared to be most accurate at  ≥ 6 s for package A and ≥ 10 s for package B. This implies that the widely recommended Tmax threshold ≥ 6 s may not be optimal for all available MRP software package. Future validation studies are required to define the optimal Tmax threshold to use for each package.
Source: Magnetic Resonance Materials in Physics, Biology and Medicine - February 22, 2023 Category: Materials Science Source Type: research

The effect of cationic albumin-conjugated PEGylated tanshinone IIA nanoparticles on neuronal signal pathways and neuroprotection in cerebral ischemia.
Abstract Targeted treatment of ischemic stroke remains problem due to the complex pathogenesis of this disease and the difficulty in drug delivery across the blood-brain barrier (BBB). In the present study, the delivery efficiency of cationic bovine serum albumin-conjugated tanshinone IIA PEGylated nanoparticles (CBSA-PEG-TIIA-NPs) in rat brain was investigated. We further explored whether the protective mechanism of CBSA-PEG-TIIA-NPs in cerebral ischemia was associated with modulating neuronal signaling pathways. The experimental cerebral ischemia model was established to evaluate the treatment efficacy of CBSA-P...
Source: Biomaterials - June 11, 2013 Category: Materials Science Authors: Liu X, Ye M, An C, Pan L, Ji L Tags: Biomaterials Source Type: research

Dimensional accuracy of tubes in cold pilgering
Publication date: May 2016 Source:Journal of Materials Processing Technology, Volume 231 Author(s): Hideaki Abe, Tetsuya Iwamoto, Yoshiaki Yamamoto, Satoru Nishida, Ryosuke Komatsu The effects of process conditions on the dimensional accuracy of tubes in cold pilgering were studied. The dimensions included the ovalities of the outer and inner diameters and the eccentricity ratio of the wall thickness. The permissible variations of the dimensions on the objective tubes were of 10μm order. The process conditions included the feed rate (1.0, 1.5, 2.0, and 2.5mm/stroke), stroke speed (140, 180, and 200 strokes/min), an...
Source: Journal of Materials Processing Technology - January 12, 2016 Category: Materials Science Source Type: research

Looking into a laser textured piston ring-liner contact
Publication date: November 2017 Source:Tribology International, Volume 115 Author(s): Sorin-Cristian Vlădescu, Alessandra Ciniero, Khizer Tufail, Arup Gangopadhyay, Tom Reddyhoff This paper presents an experimental study into the flow behaviour of lubricant in a reciprocating contact simulating a piston ring–cylinder liner pair. The aim was to understand the effects of cavitation, starvation and surface texture, as well as the interaction between these, in order to improve automotive engine performance. A custom-built test rig was used, in which a section of piston ring is loaded against a reciprocating, laser-textured...
Source: Tribology International - May 29, 2017 Category: Materials Science Source Type: research

Effects of lateral harmonic vibrations on film thickness in EHL point contacts
Publication date: January 2018 Source:Tribology International, Volume 117 Author(s): Josef Fryza, Petr Sperka, Ivan Krupka, Martin Hartl Vibrations are an integral part of machine operation and affect every elastohydrodynamically lubricated conjunctions. In the present experimental study, a rolling contact is subjected to lateral-sliding vibrations with short stroke length. Film thickness behaviour is investigated under diverse conditions including rolling speeds, stroke lengths, frequencies, loads, and variety of lubricants. The results obtained under vibrations are compared with the results for corresponding steady stat...
Source: Tribology International - September 21, 2017 Category: Materials Science Source Type: research

Evaluation of atrial septal defects with 4D flow MRI —multilevel and inter-reader reproducibility for quantification of shunt severity
ConclusionBlood flow and shunt quantification measured at multiple levels and performed by different readers are reproducible and consistent with 4D flow MRI.
Source: Magnetic Resonance Materials in Physics, Biology and Medicine - August 31, 2018 Category: Materials Science Source Type: research

Assessment of mechanical indicators of carotid plaque vulnerability: Geometrical curvature metric, plaque stresses and damage in tissue fibres.
Abstract Stroke is a major cause of death worldwide. The rupture of atherosclerotic carotid plaques is the leading single cause of stroke. Currently there is no accepted clinical measure to quantitatively assess the risk of carotid plaque rupture. Structural analyses of vulnerable plaques, using finite element (FE) analysis, have retrospectively found that regions of high stress tend to be the site of plaque rupture. The current study proposes a new clinical measure, based on plaque geometry, to assess the risk of carotid plaque rupture. This measure, named the weighted curvature difference, is based on the curvat...
Source: Journal of the Mechanical Behavior of Biomedical Materials - February 25, 2020 Category: Materials Science Authors: Ghasemi M, Nolan DR, Lally C Tags: J Mech Behav Biomed Mater Source Type: research

Fucoidan-functionalized polysaccharide submicroparticles loaded with alteplase for efficient targeted thrombolytic therapy
Biomaterials. 2021 Aug 30;277:121102. doi: 10.1016/j.biomaterials.2021.121102. Online ahead of print.ABSTRACTIntravenous administration of fibrinolytic drugs is the standard treatment of acute thrombotic diseases. However, current fibrinolytics exhibit limited clinical efficacy because of their short plasma half-lives and might trigger hemorrhagic transformations. Therefore, it is mandatory to develop innovative nanomedicine-based solutions for more efficient and safer thrombolysis with biocompatible and biodegradable thrombus-targeted nanocarrier. Herein, fucoidan-functionalized hydrogel polysaccharide submicroparticles w...
Source: Biomaterials - September 5, 2021 Category: Materials Science Authors: Alina Zenych Charl ène Jacqmarcq Rachida Aid Louise Fournier Laura M Forero Ramirez Fr édéric Chaubet Thomas Bonnard Denis Vivien Didier Letourneur C édric Chauvierre Source Type: research

Human bone marrow-derived mesenchymal stem cells play a role as a vascular pericyte in the reconstruction of human BBB on the angiogenesis microfluidic chip
In this study, we established human BBB-like microvasculature on an angiogenesis microfluidic chip and analyzed the role of human pericytes (hPCs) and human astrocytes (hACs) on the architecture of human brain microvascular endothelial cells (hBMEC)-derived microvasculature on a chip. We found that human bone marrow mesenchymal stem cells (hBM-MSCs) play a role as perivascular pericytes in tight BBB reformation with a better vessel-constrictive capacity than that of hPCs, providing evidence of reparative stem cells on BBB repair rather than a paracrine effect. We also demonstrated that pericytes play an important role in v...
Source: Biomaterials - October 28, 2021 Category: Materials Science Authors: Sumin Kim Somin Lee Jungeun Lim Hyeri Choi Habin Kang Noo Li Jeon Youngsook Son Source Type: research

A human model of arteriovenous malformation (AVM)-on-a-chip reproduces key disease hallmarks and enables drug testing in perfused human vessel networks
Biomaterials. 2022 Aug 15:121729. doi: 10.1016/j.biomaterials.2022.121729. Online ahead of print.ABSTRACTBrain arteriovenous malformations (AVMs) are a disorder wherein abnormal, enlarged blood vessels connect arteries directly to veins, without an intervening capillary bed. AVMs are one of the leading causes of hemorrhagic stroke in children and young adults. Most human sporadic brain AVMs are associated with genetic activating mutations in the KRAS gene. Our goal was to develop an in vitro model that would allow for simultaneous morphological and functional phenotypic data capture in real time during AVM disease progress...
Source: Biomaterials - August 23, 2022 Category: Materials Science Authors: Kayla Soon Mengyuan Li Ruilin Wu Angela Zhou Negar Khosraviani Williamson D Turner Joshua D Wythe Jason E Fish Sara S Nunes Source Type: research