Influence of nanoparticle size, loading, and shape on the mechanical properties of polymer nanocomposites

We study the influence of spherical, triangular, and rod-like nanoparticles on the mechanical properties of a polymernanocomposite (PNC), via coarse-grained molecular dynamics simulations. We focus on how the nanoparticle size, loading, mass, and shape influence the PNC’s elastic modulus, stress at failure and resistance against cavity formation and growth, under external stress. We find that in the regime of strong polymer-nanoparticle interactions, the formation of a polymer network via temporary polymer-nanoparticle crosslinks has a predominant role on the PNC reinforcement. Spherical nanoparticles, whose size is comparable to that of the polymermonomers, are more effective at toughening the PNC than larger spherical particles. When comparing particles of spherical, triangular, and rod-like geometries, the rod-like nanoparticles emerge as the best PNC toughening agents.Peer reviewe

Research on the Mesolithic of North Karelia in 2003–2017 - Implications for the early postglacial archaeology of Northern Europe

In this paper we describe the results of small-scale archaeological fieldwork projects carried out i North Karelia, Finland, in 2003–2014, which ended up having a far greater research impact than anyone could have anticipated. The projects yielded a multitude of new and relevant information, especially on the Early Mesolithic, including the earliest radiocarbon dates for human occupation in Eastern Fennoscandia. Results of this research have been published in a variety of venues. We use this opportunity to present the first summary of these results and to emphasize that even with discontinuous short-term funding it is possible to carry out ambitious and influential research. Over the years, Karelia has been one of the main focus areas of Mika Lavento’s research. We want to honour Mika’s 60th birthday by providing an overview of the results of our studies conducted in the northern parts of this large geographical and administrative area.Peer reviewe

Research on the Mesolithic of North Karelia in 2003–2017 - Implications for the early postglacial archaeology of Northern Europe

In this paper we describe the results of small-scale archaeological fieldwork projects carried out i North Karelia, Finland, in 2003–2014, which ended up having a far greater research impact than anyone could have anticipated. The projects yielded a multitude of new and relevant information, especially on the Early Mesolithic, including the earliest radiocarbon dates for human occupation in Eastern Fennoscandia. Results of this research have been published in a variety of venues. We use this opportunity to present the first summary of these results and to emphasize that even with discontinuous short-term funding it is possible to carry out ambitious and influential research. Over the years, Karelia has been one of the main focus areas of Mika Lavento’s research. We want to honour Mika’s 60th birthday by providing an overview of the results of our studies conducted in the northern parts of this large geographical and administrative area.Peer reviewe

Cadherin-4 plays a role in the development of zebrafish cranial ganglia and lateral line system

We previously reported that cadherin-4 (also called R-cadherin) was expressed by the majority of the developing zebrafish cranial and lateral line ganglia. Cadherin-4 (Cdh4) function in the formation of these structures in zebrafish was studied using morpholino antisense technology. Differentiation of the cranial and lateral line ganglia and lateral line nerve and neuromasts of the cdh4 morphants was analyzed using multiple neural markers. We found that a subset of the morphant cranial and lateral line ganglia were disorganized, smaller, with reduced staining, and/or with altered shape compared to control embryos. Increased cell death in the morphant ganglia likely contributed to these defects. Moreover, cdh4 morphants had shorter lateral line nerves and a reduced number of neuromasts, which was likely caused by disrupted migration of the lateral line primordia. These results indicate that Cdh4 plays a role in the normal formation of the zebrafish lateral line system and a subset of the cranial ganglia. Developmental Dynamics 236:893–902, 2007. © 2007 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/55963/1/21085_ftp.pd

Fatigue and Muscle Atrophy in a Mouse Model of Myasthenia Gravis Is Paralleled by Loss of Sarcolemmal nNOS

Myasthenia Gravis (MG) patients suffer from chronic fatigue of skeletal muscles, even after initiation of proper immunosuppressive medication. Since the localization of neuronal nitric oxide synthase (nNOS) at the muscle membrane is important for sustained muscle contraction, we here study the localization of nNOS in muscles from mice with acetylcholine receptor antibody seropositive (AChR+) experimental autoimmune MG (EAMG). EAMG was induced in 8 week-old male mice by immunization with AChRs purified from torpedo californica. Sham-injected wild type mice and mdx mice, a model for Duchenne muscular dystrophy, were used for comparison. At EAMG disease grade 3 (severe myasthenic weakness), the triceps, sternomastoid and masseter muscles were collected for analysis. Unlike in mdx muscles, total nNOS expression as well as the presence of its binding partner syntrophin ?-1, were not altered in EAMG. Immunohistological and biochemical analysis showed that nNOS was lost from the muscle membrane and accumulated in the cytosol, which is likely the consequence of blocked neuromuscular transmission. Atrophy of all examined EAMG muscles were supported by up-regulated transcript levels of the atrogenes atrogin-1 and MuRF1, as well as MuRF1 protein, in combination with reduced muscle fiber diameters. We propose that loss of sarcolemmal nNOS provides an additional mechanism for the chronic muscle fatigue and secondary muscle atrophy in EAMG and MG

Signaling and aging at the neuromuscular synapse : lessons learnt from neuromuscular diseases

The neuromuscular junction (NMJ) is a specialized synapse between motor neurons and skeletal muscle with a complex signaling network that assures highly reliable neuromuscular transmission. Diseases of the NMJ cause skeletal muscle fatigue and include inherited and acquired disorders that affect presynaptic, intrasynaptic or postsynaptic components. Moreover, fragmentation of the NMJ contributes to sarcopenia, the loss of muscle mass during aging. Studies from recent years indicate that the formation and stabilization of NMJs differs between various muscles and that this difference affects their response under pathological conditions. This review summarizes the most important mechanisms involved in the development, maintenance and dysfunction of the NMJ and it discusses their significance in myasthenic disorders and aging and as targets for possible future treatment of NMJ dysfunction