Design of decorated self-assembling peptide hydrogels as architecture for mesenchymal stem cells

Hydrogels from self-assembling ionic complementary peptides have been receiving a lot of interest from the scientific community as mimetic of the extracellular matrix that can offer three-dimensional supports for cell growth or can become vehicles for the delivery of stem cells, drugs or bioactive proteins. In order to develop a 3D "architecture" for mesenchymal stem cells, we propose the introduction in the hydrogel of conjugates obtained by chemoselective ligation between a ionic-complementary self-assembling peptide (called EAK) and three different bioactive molecules: an adhesive sequence with 4 Glycine-Arginine-Glycine-Aspartic Acid-Serine-Proline (GRGDSP) motifs per chain, an adhesive peptide mapped on h-Vitronectin and the growth factor Insulin-like Growth Factor-1 (IGF-1). The mesenchymal stem cell adhesion assays showed a significant increase in adhesion and proliferation for the hydrogels decorated with each of the synthesized conjugates; moreover, such functionalized 3D hydrogels support cell spreading and elongation, validating the use of this class of self-assembly peptides-based material as very promising 3D model scaffolds for cell cultures, at variance of the less realistic 2D ones. Furthermore, small amplitude oscillatory shear tests showed that the presence of IGF-1-conjugate did not alter significantly the viscoelastic properties of the hydrogels even though differences were observed in the nanoscale structure of the scaffolds obtained by changing their composition, ranging from long, well-defined fibers for conjugates with adhesion sequences to the compact and dense film for the IGF-1-conjugate

Critical Market Crashes

This review is a partial synthesis of the book ``Why stock market crash'' (Princeton University Press, January 2003), which presents a general theory of financial crashes and of stock market instabilities that his co-workers and the author have developed over the past seven years. The study of the frequency distribution of drawdowns, or runs of successive losses shows that large financial crashes are ``outliers'': they form a class of their own as can be seen from their statistical signatures. If large financial crashes are ``outliers'', they are special and thus require a special explanation, a specific model, a theory of their own. In addition, their special properties may perhaps be used for their prediction. The main mechanisms leading to positive feedbacks, i.e., self-reinforcement, such as imitative behavior and herding between investors are reviewed with many references provided to the relevant literature outside the confine of Physics. Positive feedbacks provide the fuel for the development of speculative bubbles, preparing the instability for a major crash. We demonstrate several detailed mathematical models of speculative bubbles and crashes. The most important message is the discovery of robust and universal signatures of the approach to crashes. These precursory patterns have been documented for essentially all crashes on developed as well as emergent stock markets, on currency markets, on company stocks, and so on. The concept of an ``anti-bubble'' is also summarized, with two forward predictions on the Japanese stock market starting in 1999 and on the USA stock market still running. We conclude by presenting our view of the organization of financial markets.Comment: Latex 89 pages and 38 figures, in press in Physics Report

Structure analysis of biologically important prokaryotic glycopolymers

Of the many post-translational modifications organisms can undertake, glycosylation is the most prevalent and the most diverse. The research in this thesis focuses on the structural characterisation of glycosylation in two classes of glycopolymer (lipopolysaccharide (LPS) and glycoprotein) in two domains of life (bacteria and archaea). The common theme linking these subprojects is the development and application of high sensitivity analytical techniques, primarily mass spectrometry (MS), for studying prokaryotic glycosylation. Many prokaryotes produce glycan arrangements with extraordinary variety in composition and structure. A further challenge is posed by additional functionalities such as lipids whose characterisation is not always straightforward. Glycosylation in prokaryotes has a variety of different biological functions, including their important roles in the mediation of interactions between pathogens and hosts. Thus enhanced knowledge of bacterial glycosylation may be of therapeutic value, whilst a better understanding of archaeal protein glycosylation will provide further targets for industrial applications, as well as insight into this post- translational modification across evolution and protein processing under extreme conditions. The first sub-project focused on the S-layer glycoprotein of the halophilic archeaon Haloferax volcanii, which has been reported to be modified by both glycans and lipids. Glycoproteomic and associated MS technologies were employed to characterise the N- and O-linked glycosylation and to explore putative lipid modifications. Approximately 90% of the S-layer was mapped and N-glycans were identified at all the mapped consensus sites, decorated with a pentasaccharide consisting of two hexoses, two hexuronic acids and a methylated hexuronic acid. The O-glycans are homogeneously identified as a disaccharide consisting of galactose and glucose. Unexpectedly it was found that membrane-derived lipids were present in the S- layer samples despite extensive purification, calling into question the predicted presence of covalently linked lipid. The H. volcanii N-glycosylation is mediated by the products of the agl gene cluster and the functional characterisation of members of the agl gene cluster was investigated by MS analysis of agl-mutant strains of the S-layer. Burkholderia pseudomallei is the causative agent of melioidosis, a serious and often fatal disease in humans which is endemic in South-East Asia and other equatorial regions. Its LPS is vital for serum resistance and the O-antigen repeat structures are of interest as vaccine targets. B. pseudomallei is reported to produce several polysaccharides, amongst which the already characterised ‘typical’ O-antigen of K96243 represents 97% of the strains. The serologically distinct ‘atypical’ strain 576 produces a different LPS, whose characterisation is the subject of this research project. MS strategies coupled with various hydrolytic and chemical derivatisation methodologies were employed to define the composition and potential sequences of the O-antigen repeat unit. These MS strategies were complemented by a novel NMR technique involving embedding of the LPS into micelles. Taken together the MS and NMR data have revealed a highly unusual O-antigen structure for atypical LPS which is remarkably different from the typical O-antigen. The development of structural analysis tools in MS and NMR applicable to the illustrated types of glycosylation in these prokaryotes will give a more consistent approach to sugar characterisation and their modifications thus providing more informative results for pathogenicity and immunological studies as well as pathway comparisons.Open Acces

PAVEL: Decorative Patterns with Packed Volumetric Elements

Many real-world hand-crafted objects are decorated with elements that are packed onto the object's surface and deformed to cover it as much as possible. Examples are artisanal ceramics and metal jewelry. Inspired by these objects, we present a method to enrich surfaces with packed volumetric decorations. Our algorithm works by first determining the locations in which to add the decorative elements and then removing the non-physical overlap between them while preserving the decoration volume. For the placement, we support several strategies depending on the desired overall motif. To remove the overlap, we use an approach based on implicit deformable models creating the qualitative effect of plastic warping while avoiding expensive and hard-to-control physical simulations. Our decorative elements can be used to enhance virtual surfaces, as well as 3D-printed pieces, by assembling the decorations onto real-surfaces to obtain tangible reproductions.Comment: 11 page

Mechatronics applied to scale model decoration

The European toy industry is very heavily dependent on manual labour and therefore vulnerable to Far Eastern competitors, who have the advantage of lower labour costs. Automation is Europe's best hope of beating off this oriental challenge. The aim of the project described within this thesis is to investigate the replacement of a traditionally manual series of operations by flexible automation to provide the basis for higher productivity and a greater degree of responsiveness to product change, leading to Just In Time Manufacture with reduced Work In Progress, while still retaining the high quality traditionally associated with the product. This thesis presents one of the first working attempts to this end, represented by a proof-of­concept cell designed and commissioned for investigating the many problems and possibilities associated with the decoration of scale models of cars and trains. The cell was designed using the Mechatronics approach which means that the various mechanical, electrical and electronic and computing possibilities have been taken into account from the start of the design stage. The proof-of-concept cell consists of five stations which provide the necessary means of loading the models in the cell, identifying the models and their orientation, decorating the models, inspecting the decorated models and finally palletising them for assembly. The industrial partners for the project were Hornby Hobbies Limited, J-L Automation and Staubli Unimation. Because this project centres around the present decoration operations at Hornby Hobbies Limited, which is heavily dependant on pad printing, an overview of pad printing is included. This will give the reader a background to the problems faced during the project. Before describing the proof-of-concept cell and its hardware and software components, the present factory based method and the constraints put on the project by Hornby Hobbies Limited are explained so that the reasons for choices within the cell will be more readily understood. A brief history of Scalextric is also included so that the reader may also understand some of the historical problems associated with the product. The result of this mechatronic approach are two fold: a) the efficiency of the cell is improved because the individual parts are working at optimal efficiency b) the cell has a greater degree of flexibility because of the re-programming facilities embedded in each of its component parts. This Mechatronic investigation has led to new concepts for pad printing and assembly operations and these are described in detail in the conclusions

Current and future challenges of the ceramic tile firms: (the case of the INKJET technological innovation)

Treball final de Grau en Administració d’Empreses. Codi: AE1049. Curs acadèmic 2014-2015The following work integrates three theoretical perspectives in the field of economics: the situation in the ceramic sector at a global and national level, the perspective of the territory (also known as a “cluster”) and the innovation and new technologies in the same sector. An analysis of the current and future challenges of the companies in the Spanish ceramic sector will be realized. For it, first the situation of the sector will be analyzed from a European and global perspective, with data from the production and consumption of tiles of the main countries as well as data on export and import. Once the situation of the sector is analyzed from this perspective, I will study carefully the territorial agglomerations, like the clusters, which have specific characteristics in terms of the flow of knowledge through their networks. In addition, I will focus on the Spanish situation in particular, in the Italy-Spain cluster, and also in the importance of the congregation in this kind of companies in the province of Castellón. Finally, I will emphasize innovation since it is probably one of the best indicators of value creation by companies and thus the importance of study and research in R & D. In the case of this work, I will talk about the inkjet technology in the ceramic industry, since it has supposed a revolutionary change for the companies in the sector