VoroCrust: Voronoi Meshing Without Clipping

Polyhedral meshes are increasingly becoming an attractive option with particular advantages over traditional meshes for certain applications. What has been missing is a robust polyhedral meshing algorithm that can handle broad classes of domains exhibiting arbitrarily curved boundaries and sharp features. In addition, the power of primal-dual mesh pairs, exemplified by Voronoi-Delaunay meshes, has been recognized as an important ingredient in numerous formulations. The VoroCrust algorithm is the first provably-correct algorithm for conforming polyhedral Voronoi meshing for non-convex and non-manifold domains with guarantees on the quality of both surface and volume elements. A robust refinement process estimates a suitable sizing field that enables the careful placement of Voronoi seeds across the surface circumventing the need for clipping and avoiding its many drawbacks. The algorithm has the flexibility of filling the interior by either structured or random samples, while preserving all sharp features in the output mesh. We demonstrate the capabilities of the algorithm on a variety of models and compare against state-of-the-art polyhedral meshing methods based on clipped Voronoi cells establishing the clear advantage of VoroCrust output.Comment: 18 pages (including appendix), 18 figures. Version without compressed images available on https://www.dropbox.com/s/qc6sot1gaujundy/VoroCrust.pdf. Supplemental materials available on https://www.dropbox.com/s/6p72h1e2ivw6kj3/VoroCrust_supplemental_materials.pd

Effect of poly(ethylene glycol) on insulin stability and cutaneous cell proliferation in vitro following cytoplasmic delivery of insulin-loaded nanoparticulate carriers – A potential topical wound management approach

We describe the development of a nanoparticulate system, with variation of poly(ethylene glycol) (PEG) content, capable of releasing therapeutic levels of bioactive insulin for extended periods of time. Recombinant human insulin was encapsulated in poly(d,l-lactide-co-glycolide) nanoparticles, manufactured with variation in poly(ethylene glycol) content, and shown to be stable for 6days using SDS-PAGE, western blot and MALDI MS. To determine if insulin released from this sustained release matrix could stimulate migration of cell types normally active in dermal repair, a model wound was simulated by scratching confluent cultures of human keratinocytes (HaCaT) and fibroblasts (Hs27). Although free insulin was shown to have proliferative effect, closure of in vitro scratch fissures was significantly faster following administration of nano-encapsulated insulin. This effect was more pronounced in HaCaT cells when compared to Hs27 cells. Variation in PEG content had the greatest effect on NP size, with a lesser influence on scratch closure times. Our work supports a particulate uptake mechanism that provides for intracellular insulin delivery, leading to enhanced cell proliferation. When placed into an appropriate topical delivery vehicle, such as a hydrogel, the extended and sustained topical administration of active insulin delivered from a nanoparticulate vehicle shows promise in promoting tissue healing

Facile mechanochemical synthesis of non-stoichiometric silica-carbon composite for enhanced lithium storage properties

A large number of new electrode materials and novel structural designs are emerging for lithium-ion batteries, yet scalable synthesis and raw material costs still hinder the practical application of such materials. Here, we designed and fabricated a low-cost SiOx/C composite by a facile and scalable mechanofusion route with a ball-milling method. We selected aerosil and graphite precursor-needle coke, which are two widely used materials in industry, as a silicon source and carbon source, respectively. This SiOx/C composite shows a high reversible capacity (ca. 550 mAh g−1) at the 180th cycle and good rate performance. Our scalable synthesis route of electrode materials can stimulate the progress of other energy storage technologies for practical applications

Sampling Conditions for Conforming Voronoi Meshing by the VoroCrust Algorithm

We study the problem of decomposing a volume bounded by a smooth surface into a collection of Voronoi cells. Unlike the dual problem of conforming Delaunay meshing, a principled solution to this problem for generic smooth surfaces remained elusive. VoroCrust leverages ideas from alpha-shapes and the power crust algorithm to produce unweighted Voronoi cells conforming to the surface, yielding the first provably-correct algorithm for this problem. Given an epsilon-sample on the bounding surface, with a weak sigma-sparsity condition, we work with the balls of radius delta times the local feature size centered at each sample. The corners of this union of balls are the Voronoi sites, on both sides of the surface. The facets common to cells on opposite sides reconstruct the surface. For appropriate values of epsilon, sigma and delta, we prove that the surface reconstruction is isotopic to the bounding surface. With the surface protected, the enclosed volume can be further decomposed into an isotopic volume mesh of fat Voronoi cells by generating a bounded number of sites in its interior. Compared to state-of-the-art methods based on clipping, VoroCrust cells are full Voronoi cells, with convexity and fatness guarantees. Compared to the power crust algorithm, VoroCrust cells are not filtered, are unweighted, and offer greater flexibility in meshing the enclosed volume by either structured grids or random samples

Risks and benefits of prophylactic inferior vena cava filters in patients undergoing bariatric surgery

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97509/1/jhm2013.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/97509/2/jhm2013-sup-0001-suppinfo.pd

Public–Private Partnership in Tunisia: Enfidha Airport Assessment of an Infrastructure Achievement

One of the largest recent private-sector investments and the first airport private-sector concession in the Maghreb is Enfidha Airport, a key factor in the success of the Tunisian Government’s public– private partnership (PPP) strategy. However, since Tunisia’s Jasmine Revolution, political and social turmoil is sweeping the country and worsening the economic indicators. This article aims to assess this PPP infrastructure, allowing us to determine if it is profitable in the long term and contributes therefore to the economic growth. The case study reveals the key role of the economic, social, and political environment in Tunisia, the dawn of the Arab Spring

A low-cost paper-based platform for fast and reliable screening of cellular interactions with materials

A paper-based platform was developed and tested for studies on basic cell culture, material biocompatibility, and activity of pharmaceuticals in order to provide a reliable, robust and low-cost cell study platform. It is based upon a paper or paperboard support, with a nanostructured Latex coating to provide an enhanced cell growth and sufficient barrier properties. Wetting is Limited to regions of interest using a flexographically printed hydrophobic polydimethylsiloxane Layer with circular non-print areas. The nanostructured coating can be substituted for another coating of interest, or the regions of interest functionalized with a material to be studied. The platform is fully up-scalable, being produced with roll-to-roll rod coating, flexographic and inkjet printing methods. Results show that the platform efficiency is comparable to multi-well plates in colorimetric assays in three separate studies: a cell culture study, a biocompatibility study, and a drug screening study. The color intensity is quantified by using a common office scanner or an imaging device and the data is analyzed by a custom computer software without the need for expensive screening or analysis equipment