An Evaluation of Non-Stochastic Lattice Structures Fabricated Via Electron Beam Melting

Metal foam structures have many applications and can be used as structural supports, heat exchangers, shock absorbers, and implant materials. Stochastic metal foams having different cell sizes and densities have been commercially available for a number of years. This paper addresses a different type of foams which are known as non-stochastic foams, or lattice structures. These foams have a well defined repeating unit cell structure rather than the random cell structure in commercially available stochastic foams. The paper reports on preliminary research on the fabrication of non-stochastic Ti-6Al-4V alloy foams using the Electron Beam Melting process. Behavior of the structures in compression, bending, and low cycle repeating load tests are discussed, and recommendations about cell geometry and processing conditions are made.Mechanical Engineerin

3D Object Discovery and Modeling Using Single RGB-D Images Containing Multiple Object Instances

Unsupervised object modeling is important in robotics, especially for handling a large set of objects. We present a method for unsupervised 3D object discovery, reconstruction, and localization that exploits multiple instances of an identical object contained in a single RGB-D image. The proposed method does not rely on segmentation, scene knowledge, or user input, and thus is easily scalable. Our method aims to find recurrent patterns in a single RGB-D image by utilizing appearance and geometry of the salient regions. We extract keypoints and match them in pairs based on their descriptors. We then generate triplets of the keypoints matching with each other using several geometric criteria to minimize false matches. The relative poses of the matched triplets are computed and clustered to discover sets of triplet pairs with similar relative poses. Triplets belonging to the same set are likely to belong to the same object and are used to construct an initial object model. Detection of remaining instances with the initial object model using RANSAC allows to further expand and refine the model. The automatically generated object models are both compact and descriptive. We show quantitative and qualitative results on RGB-D images with various objects including some from the Amazon Picking Challenge. We also demonstrate the use of our method in an object picking scenario with a robotic arm

Enhanced photoresponse of conformal TiO2/Ag nanorod array-based Schottky photodiodes fabricated via successive glancing angle and atomic layer deposition

Cataloged from PDF version of article.In this study, the authors demonstrate a proof of concept nanostructured photodiode fabrication method via successive glancing angle deposition (GLAD) and atomic layer deposition (ALD). The fabricated metal-semiconductor nanorod (NR) arrays offer enhanced photoresponse compared to conventional planar thin-film counterparts. Silver (Ag) metallic NR arrays were deposited on Ag-film/Si templates by utilizing GLAD. Subsequently, titanium dioxide (TiO2) was deposited conformally on Ag NRs via ALD. Scanning electron microscopy studies confirmed the successful formation of vertically aligned Ag NRs deposited via GLAD and conformal deposition of TiO2 on Ag NRs via ALD. Following the growth of TiO2 on Ag NRs, aluminum metallic top contacts were formed to complete the fabrication of NR-based Schottky photodiodes. Nanostructured devices exhibited a photo response enhancement factor of 1.49 × 102 under a reverse bias of 3 V. © 2014 American Vacuum Societ

The Use of Layered Freeform Fabrication Technologies to Produce Tissue Engineering Scaffolds for Skull Patches

Congenital skull defects in infants are difficult to correct using metal plates due to the growth of the skull. Tissue engineering of bone patches could be the answer to help such patients. Custom scaffolds have been designed based on Computed Tomography (CT) images of the patient’s skull. An in-house developed single screw extruder, casting and a commercial laser cutter has been evaluated in the fabrication of pure polycaprolactone (PCL) scaffolds as well as PCL mixed with hydroxyapatite (HA) scaffolds. Evaluation criteria for each process included the ability to maintain an optimal pore size for cells to proliferate, inclusion of micro surface properties for cell adhesion, incorporation of hydroxyapatite, and ability to maintain desired shape. The mechanical properties of the fabricated scaffolds will be presented in this paper as well as initial cell seeding results with human adipose-derived adult stem (hADAS) cells.Mechanical Engineerin

Conformational Heterogeneity of Karyopherinβ2 Is Segmental

SummaryKaryopherinβ2 (Kapβ2) or transportin imports numerous RNA binding proteins into the nucleus. Kapβ2 binds substrates in the cytoplasm and targets them through the nuclear pore complex, where RanGTP dissociates them in the nucleus. Here we report the 3.0 Å crystal structure of unliganded Kapβ2, which consists of a superhelix of 20 HEAT repeats. Together with previously reported structures of NLS and Ran complexes, this structure provides understanding of conformational heterogeneity that accompanies ligand binding. The Kapβ2 superhelix is divided into three major segments. Two of them (HEAT repeats 9–13 and 14–18), which constitute the substrate binding site, are rigid elements that rotate relative to each other about a flexible hinge. The third (HEAT repeats 1–8), which constitutes the Ran binding site, exhibits conformational changes throughout its length. An analogous segmental architecture is also observed in Importinβ, suggesting that it is functionally significant and may be conserved in other import karyopherins

Dogma 95 manifesto and the ordinary act of filmmaking

From the beginning of its conception Dogma 95 manifesto incited several debates related with cinema and other realms of culture. The manifesto became a motivation for a series of internationally acclaimed Danish films alongside it spurred many independent filmmakers from all around of the world. Analyzing the emergence, institutionalization and expansion of the Dogma concept offers many possibilities in understanding the zeitgeist of the last decade of the longest century of history. Politics and aesthetics always went hand in hand in the Dogma program. The main concern of the manifesto was the political economy of filmmaking. Dogma 95 manifesto definitely offered a new filmmaking strategy apart from Hollywood whose visual ideology is determined by the oligopolistic market and international capital structures. Also within the context of the European cinema the Dogma movement was different since it did not closeted itself within a debate between globalization and national cultures. Following Lefebvre's ideas one may argue that Dogma 95 manifesto proposed to construct a new social space for filmmaking which is more inclusive and democratic. Even though the film aesthetics seems to be denied in the manifesto, an analysis based upon the premises of the performance theory shows us the fact that Dogma 95 manifesto proposed a frame within which the political criticism is included, and this frame is not exempt from the realm of aesthetics. Lars von Trier's Idiots can be considered as a critical account on the utopian Dogma project. Through its self reflexivity, inclusive yet provocative nature Dogma 95 manifesto spurs an intellectual interrogation about the very basics and the future of cinema

RAM function is dependent on Kapβ2-mediated nuclear entry

Eukaryotic gene expression is dependent on the modification of the first transcribed nucleotide of pre-mRNA by the addition of the 7-methylguanosine cap. The cap protects transcripts from exonucleases and recruits complexes which mediate transcription elongation, processing and translation initiation. The cap is synthesized by a series of reactions which link 7-methylguanosine to the first transcribed nucleotide via a 5′ to 5′ triphosphate bridge. In mammals, cap synthesis is catalysed by the sequential action of RNGTT (RNA guanylyltransferase and 5′-phosphatase) and RNMT (RNA guanine-7 methyltransferase), enzymes recruited to RNA pol II (polymerase II) during the early stages of transcription. We recently discovered that the mammalian cap methyltransferase is a heterodimer consisting of RNMT and the RNMT-activating subunit RAM (RNMT-activating mini-protein). RAM activates and stabilizes RNMT and thus is critical for cellular cap methylation and cell viability. In the present study we report that RNMT interacts with the N-terminal 45 amino acids of RAM, a domain necessary and sufficient for maximal RNMT activation. In contrast, smaller components of this RAM domain are sufficient to stabilize RNMT. RAM functions in the nucleus and we report that nuclear import of RAM is dependent on PY nuclear localization signals and Kapβ2 (karyopherin β2) nuclear transport protein