Crystal structure of the anthrax lethal factor

Lethal factor (LF) is a protein (relative molecular mass 90,000) that is critical in the pathogenesis of anthrax(1-3). It is a highly specific protease that cleaves members of the mitogen-activated protein kinase kinase (MAPKK) family near to their amino termini, leading to the inhibition of one or more signalling pathways(4-6). Here we describe the crystal structure of LF and its complex with the N terminus of MAPKK-2. LF comprises four domains: domain I binds the membrane-translocating component of anthrax toxin, the protective antigen (PA); domains II, III and IV together create a long deep groove that holds the 16-residue N-terminal tail of MAPKK-2 before cleavage. Domain II resembles the ADP-ribosylating toxin from Bacillus cereus, but the active site has been mutated and recruited to augment substrate recognition. Domain III is inserted into domain II, and seems to have arisen from a repeated duplication of a structural element of domain II. Domain IV is distantly related to the zinc metalloprotease family, and contains the catalytic centre; it also resembles domain I. The structure thus reveals a protein that has evolved through a process of gene duplication, mutation and fusion, into an enzyme with high and unusual specificity.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62772/1/414229a0.pd

Is hosting a sporting mega-event worth it to the host city? Impact of hosting sporting mega-events on residents' sense of community

The present study empirically investigates a model of residents’ intention to support the Asian Games based on the theory of reasoned action (TRA) and social exchange theory (SET). The model proposes that residents’ intention to support hosting a sporting mega-event, mediates the relationship between the benefits they perceive in serving as host and their sense of community. The results indicate that the perceived positive benefits and intention of residents to support, affect their sense of community. Thus, in order to develop a sense of community of residents, these aspects should be enhanced in researchers’ models. The findings of this work will provide authorities and event organisers with comprehensive and multidimensional knowledge about the positive impacts of hosting mega-events, as well as information important to determining the likelihood that their objectives will be realised as expected. Finally, certain theoretical and managerial implications are also discussed.Keywords: Sporting mega-event; Hosting a sporting mega-event; Perceived benefits; Intention to support; Sense of community; Asian Games

QCanvas: An Advanced Tool for Data Clustering and Visualization of Genomics Data

We developed a user-friendly, interactive program to simultaneously cluster and visualize omics data, such as DNA and protein array profiles. This program provides diverse algorithms for the hierarchical clustering of two-dimensional data. The clustering results can be interactively visualized and optimized on a heatmap. The present tool does not require any prior knowledge of scripting languages to carry out the data clustering and visualization. Furthermore, the heatmaps allow the selective display of data points satisfying user-defined criteria. For example, a clustered heatmap of experimental values can be differentially visualized based on statistical values, such as p-values. Including diverse menu-based display options, QCanvas provides a convenient graphical user interface for pattern analysis and visualization with high-quality graphics

Crash Performance of Strength Gradient Tube Induced by Selective Laser Patterning

This paper presents an investigation of the performance of a 22 MnB5 tube after local heat treatment according to a patterning shape under dynamic crash test conditions to propose the patterning shape with the best energy absorption efficiency. Numerical simulations support experimental results to validate the deformation mode during dynamic crash test as well as the strain distribution of the specimen. The helical patterning not only demonstrates the highest axial loading force and energy absorbance in both static and dynamic crash tests, but also can be easily fabricated in a short time. The helical pattern can optimize different pitch sizes according to the thickness and diameter of the cylindrical tube, and it has the highest energy absorption rate with 83.0% in dynamic conditions

New possibilities in polymer binder jetting additive manufacturing via infiltration and warm isostatic pressing

Binder jetting (BJ) leads to low mechanical properties and high porosity because it uses binders to selectively bind powder materials. To overcome the poor characteristics of BJ parts, infiltration is a generally applied post-process; however, it results in a low infiltration volume and large number of residual voids in the uninfiltrated section. This study aims to effectively improve the mechanical properties, microstructure, and density of polymer-based BJ parts by overcoming limitations of infiltration process via warm isostatic pressing (WIP) that applies heat and pressure. The infiltrated specimens with epoxy are vacuum-packed, and the WIP process is performed at a target temperature of 130 °C and pressure of 8 MPa. Consequently, the infiltration volume increases by up to 195.2%, and the number of residual voids in the uninfiltrated section, where the infiltrants do not reach, is significantly reduced. Further, in terms of the mechanical properties, the tensile strength increases by 1215%, compressive strength by 1280%, and flexural strength by 535%. In addition, the results of transmission, scanning electron microscopy, and microcomputer X-ray tomography reveal a clear decrease in the number of voids

Antagonistic Roles of PhyA and PhyB in Far-Red Light-Dependent Leaf Senescence in Arabidopsis thaliana

Leaf senescence is regulated by diverse developmental and environmental factors to maximize plant fitness. The red to far-red light ratio (R:FR) detected by plant phytochromes is reduced under vegetation shade, thus initiating leaf senescence. However, the role of phytochromes in promoting leaf senescence under FR-enriched conditions is not fully understood. In this study, we investigated the role of phyA and phyB in regulating leaf senescence under FR in Arabidopsis thaliana (Arabidopsis). FR enrichment and intermittent FR pulses promoted the senescence of Arabidopsis leaves. Additionally, phyA and phyB mutants showed enhanced and repressed senescence phenotypes in FR, respectively, indicating that phyA and phyB antagonistically regulate FR-dependent leaf senescence. Transcriptomic analysis using phyA and phyB mutants in FR identified differentially expressed genes (DEGs) involved in leaf senescence-related processes, such as responses to light, phytohormones, temperature, photosynthesis and defense, showing opposite expression patterns in phyA and phyB mutants. These contrasting expression profiles of DEGs support the antagonism between phyA and phyB in FR-dependent leaf senescence. Among the genes showing antagonistic regulation, we confirmed that the expression of WRKY6, which encodes a senescence-associated transcription factor, was negatively and positively regulated by phyA and phyB, respectively. The wrky6 mutant showed a repressed senescence phenotype compared with the wild type in FR, indicating that WRKY6 plays a positive role in FR-dependent leaf senescence. Our results imply that antagonism between phyA and phyB is involved in fine-tuning leaf senescence under varying FR conditions in Arabidopsis.(c) The Author(s) 2018

Increased interlayer bonding strength of short carbon fiber composite fabricated by material extrusion via warm isostatic pressing (WIP) process

Recently, short carbon fiber-reinforced plastic (SFRP) has been selected as a filament material to improve the strength of components fabricated by material extrusion (ME). However, despite the improved material properties, the weak interlayer bonding and voids present in the microstructure constitute defects that cause anisotropy in the SFRP composite and deteriorate its mechanical properties such as the tensile, compressive, and flexural strengths. In this study, warm isostatic pressing (WIP) was investigated as a means to increase the interlayer bonding force and reduce the voids. To increase the efficiency of WIP, vacuum packing was investigated as a means to promote interfacial strength and diffusion between the layers. The WIP process improved the tensile, compressive, and flexural properties, and the anisotropy decreased with increasing interlayer bonding force. In addition, the thermal properties improved with an increase in the degree of crystallinity, and the voids in the microstructure were effectively reduced. These results indicate that WIP is a promising post-processing treatment for ME-fabricated SFRP parts.Published versionThis study was supported by (1415185655, Development of DfAM based 3D Printing technology for combustor parts of private sector initiative small space launcher engine) and a Korea Institute of Industrial Technology (KITECH) internal project (1711175147, Development of 3D printing commercialization technology for military parts and demonstration support technology)

Comparison of Biocompatibility of Calcium Silicate-Based Sealers and Epoxy Resin-Based Sealer on Human Periodontal Ligament Stem Cells

The aim of this study was to evaluate the biocompatibility of calcium silicate-based sealers (CeraSeal and EndoSeal TCS) and epoxy resin-based sealer (AH-Plus) in terms of cell viability, inflammatory response, expression of mesenchymal phenotype, osteogenic potential, cell attachment, and morphology, of human periodontal ligament stem cells (hPDLSCs). hPDLSCs were acquired from the premolars (n = 4) of four subjects, whose ages extended from 16 to 24 years of age. Flow cytometry analysis showed stemness of hPDLSCs was maintained in all materials. In cell viability test, AH-Plus showed the lowest cell viability, and CeraSeal showed significantly higher cell viability than others. In ELISA test, AH-Plus showed higher expression of IL-6 and IL-8 than calcium silicate-based sealers. In an osteogenic potential test, AH-Plus showed a lower expression level than other material; however, EndoSeal TCS showed a better expression level than others. All experiments were repeated at least three times per cell line. Scanning electronic microscopy studies showed low degree of cell proliferation on AH-Plus, and high degree of cell proliferation on calcium silicate-based sealers. In this study, calcium silicate-based sealers appear to be more biocompatible and less cytotoxic than epoxy-resin based sealers

Continuous-Wave Laser-Induced Transfer of Metal Nanoparticles to Arbitrary Polymer Substrates

Laser-induced forward transfer (LIFT) and selective laser sintering (SLS) are two distinct laser processes that can be applied to metal nanoparticle (NP) ink for the fabrication of a conductive layer on various substrates. A pulsed laser and a continuous-wave (CW) laser are utilized respectively in the conventional LIFT and SLS processes; however, in this study, CW laser-induced transfer of the metal NP is proposed to achieve simultaneous sintering and transfer of the metal NP to a wide range of polymer substrates. At the optimum laser parameters, it was shown that a high-quality uniform metal conductor was created on the acceptor substrate while the metal NP was sharply detached from the donor substrate, and we anticipate that such an asymmetric transfer phenomenon is related to the difference in the adhesion strengths. The resultant metal electrode exhibits a low resistivity that is comparable to its bulk counterpart, together with strong adhesion to the target polymer substrate. The versatility of the proposed process in terms of the target substrate and applicable metal NPs brightens its prospects as a facile manufacturing scheme for flexible electronics

Stretchable and Transparent Kirigami Conductor of Nanowire Percolation Network for Electronic Skin Applications

Recent research progress of relieving discomfort between electronics and human body involves serpentine designs, ultrathin films, and extraordinary properties of nanomaterials. However, these strategies addressed thus far each face own limitation for achieving desired form of electronic-skin applications. Evenly matched mechanical properties anywhere on the body and imperceptibility of electronics are two essentially required characteristics for future electronic-skin (E-skin) devices. Yet accomplishing these two main properties simultaneously is still very challenging. Hence, we propose a novel fabrication method to introduce kirigami approach to pattern a highly conductive and transparent electrode into diverse shapes of stretchable electronics with multivariable configurability for E-skin applications. These kirigami engineered patterns impart tunable elasticity to the electrodes, which can be designed to intentionally limit strain or grant ultrastretchability depending on applications over the range of 0 to over 400% tensile strain with strain-invariant electrical property and show excellent strain reversibility even after 10 000 cycles stretching while exhibiting high optical transparency (>80%). The versatility of this work is demonstrated by ultrastretchable transparent kirigami heater for personal thermal management and conformal transparent kirigami electrophysiology sensor for continuous health monitoring of human body conditions. Finally, by integrating E-skin sensors with quadrotor drones, we have successfully demonstrated human-machine-interface using our stretchable transparent kirigami electrodes.Y