Interconnected Self-Propagating Photopolymer Waveguides: An Alternative to Stereolithography for Rapid Formation of Lattice-Based Open-Cellular Materials

Recently, a new technique has been developed to create unique open-cellular materials with micro-scale truss, or lattice features ranging from tens to hundreds of microns. These materials are formed from a three-dimensional, interconnected array of self-propagating photopolymer waveguides. By utilizing this self-propagating effect, three-dimensional open-cellular polymer materials can be formed in seconds. In addition, intrinsic to the process is the ability to control specific micro-lattice parameters which ultimately affect the bulk material properties. Unlike stereolithography, this new fabrication technique is rapid (~ minutes to form an entire part) and relies on a single two-dimensional exposure surface to form three-dimensional structures (thickness > 25 mm possible). This combination of speed and planar scalability opens the possibility for large-scale mass manufacturing. The utility of these new materials range from lightweight energy absorbing structures to thermal management materials to bio-scaffolds.Mechanical Engineerin

Coronin-1C Protein and Caveolin Protein Provide Constitutive and Inducible Mechanisms of Rac1 Protein Trafficking

Sustained directional fibroblast migration requires both polarized activation of the protrusive signal, Rac1, and redistribution of inactive Rac1 from the rear of the cell so that it can be redistributed or degraded. In this work, we determine how alternative endocytic mechanisms dictate the fate of Rac1 in response to the extracellular matrix environment. We discover that both coronin-1C and caveolin retrieve Rac1 from similar locations at the rear and sides of the cell. We find that coronin-1C-mediated extraction, which is responsible for Rac1 recycling, is a constitutive process that maintains Rac1 protein levels within the cell. In the absence of coronin-1C, the effect of caveolin-mediated endocytosis, which targets Rac1 for proteasomal degradation, becomes apparent. Unlike constitutive coronin-1C-mediated trafficking, caveolin-mediated Rac1 endocytosis is induced by engagement of the fibronectin receptor syndecan-4. Such an inducible endocytic/degradation mechanism would predict that, in the presence of fibronectin, caveolin defines regions of the cell that are resistant to Rac1 activation but, in the absence of fibronectin leaves more of the membrane susceptible to Rac1 activation and protrusion. Indeed, we demonstrate that fibronectin-stimulated activation of Rac1 is accelerated in the absence of caveolin and that, when caveolin is knocked down, polarization of active Rac1 is lost in FRET experiments and culminates in shunting migration in a fibrous fibronectin matrix. Although the concept of polarized Rac1 activity in response to chemoattractants has always been apparent, our understanding of the balance between recycling and degradation explains how polarity can be maintained when the chemotactic gradient has faded

In vitro approaches to the prediction of percutaneous absorption and metabolism A study of ethoxylates

SIGLEAvailable from British Library Document Supply Centre- DSC:DX179398 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Physiological responses to polysaccharides : are rats and pigs good models for humans ?

International audienc

Covalent attachment of organic monolayers to silicon carbide surfaces

This work presents the first alkyl monolayers covalently bound on HF-treated silicon carbide surfaces (SiC) through thermal reaction with 1-alkenes. Treatment of SiC with diluted aqueous HF solutions removes the native oxide layer (SiO2) and provides a reactive hydroxyl-covered surface. Very hydrophobic methyl-terminated surfaces (water contact angle = 107) are obtained on flat SiC, whereas attachment of -functionalized 1-alkenes also yields well-defined functionalized surfaces. Infrared reflection absorption spectroscopy, ellipsometry, and X-ray photoelectron spectroscopy measurements are used to characterize the monolayers and show their covalent attachment. The resulting surfaces are shown to be extremely stable under harsh acidic conditions (e.g., no change in after 4 h in 2 M HCl at 90 C), while their stability in alkaline conditions (pH = 11, 60 C) also supersedes that of analogous monolayers such as those on Au, Si, and SiO2. These results are very promising for applications involving functionalized silicon carbide

Dinâmica populacional de bruquíneos (Coleoptera, Chrysomelidae) em Senna multijuga (Rich.) H. S. Irwin & Barneby (Caesalpinaceae) Population dynamics of bruchines (Coleoptera, Chrysomelidae) in Senna multijuga (Rich.) H. S. Irwin & Barneby (Caesalpinaceae)

Senna multijuga (Rich.) H. S. Irwin & Barneby (Caesalpinaceae) é uma planta ornamental comum no sudeste do Brasil, suscetível ao dano por bruquíneos predadores de sementes. Com o objetivo de identificar os predadores de suas sementes e determinar seus ciclos populacionais, frutos de cinco árvores foram coletados em 2000 e 2001 e acondicionados em casa de vegetação até a emergência de adultos. Os bruquíneos foram identificados como Sennius crudelis Ribeiro-Costa & Reynaud, 1998, S. puncticollis (Fåhraeus, 1839) e S. nappi Ribeiro-Costa & Reynaud, 1998. Sennius crudelis foi a espécie mais abundante em 2000, seguida por S. puncticollis e S. nappi. Em 2001, Sennius crudelis foi seguida por S. nappi e S. puncticollis. Diferenças foram observadas entre as árvores com relação ao período de frutificação, refletindo na oviposição. O período de emergência dos adultos se inicia em julho tanto em casa de vegetação quan-to no campo. Os resultados demonstraram que as dinâmicas populacionais dos bruquíneos são complexas e a compreensão desses processos contribui para responder a muitas outras questões ecológicas do grupo.<br>Senna multijuga (Rich.) H. S. Irwin & Barneby (Caesalpinaceae) is a native ornamental tree common in southeastern Brazil and susceptible to seed damage due to bruchines. To identify seed predators and determine their population cycles, fruits from five trees were collected in 2000 and 2001 and stored in a green house until adult emerged. Seed beetles were then identified as Sennius crudelis Ribeiro-Costa & Reynaud, 1998, S. puncticollis (Fåhraeus, 1839) and S. nappi Ribeiro-Costa & Reynaud, 1998. Sennius crudelis was the most abundant species in 2000 followed by S. puncticollis and S. nappi. In 2001, Sennius crudelis was followed by S. nappi and S. puncticollis. Differences were observed among trees relating to fruiting period which reflected in the oviposition. Adult emergence begins in July in the green house and in the field. These results show that bruchine beetles have complex population dynamics, and understanding those dynamics is important to answer other ecological questions of the group