Finite Element Analysis of Moso Bamboo-Reinforced Southern Pine Osb Composite Beams

A finite element (FE) analysis was performed to investigate the flexural properties of a structural composite lumber—Moso bamboo (Phyllostachys pubescens) reinforced southern pine oriented strand-board (OSB). Parametric analyses were conducted to investigate the stress and displacement distributions. Various beam configurations as affected by glue, web structure, flange composition, and bamboo-OSB combination were considered. The comparison of the numerical results from the selected models with those from bending tests was also performed. Finally, a rational design criterion for this type of composite beam was proposed based on the analytical and experimental studies. Bamboo is capable of improving the flexural properties of the OSB for use as a structural beam or joist. At a given cross section of about 30 X 140 mm, for instance, two-layer (6.4-mm thickness each) laminated bamboo flange can increase the OSB beam's maximum bending stress by 60 to 70% and double its stiffness. The total flange thickness, rather than the thickness of each layer, controls the beam deflection while the flange with a thinner layer (3.2 mm) resulted in higher bending, vertical, and transverse stresses but lower in-plane shear stress. More reinforcing material in the composite beam could reduce the maximum bending stress but would likely increase beam weight and processing cost. From this study, it is suggested that a two-layer flanged composite beam would be favorable from a material processing standpoint as well as superior in engineering performance over other configurations of bamboo-OSB composite beam product

Institutional regime shift in intellectual property rights and innovation strategies of firms in China

This study develops a novel conceptual framework to understand the differential impact of formal institutional regime shift in intellectual property rights on the innovation and patenting strategies of Chinese and Western firms operating in China. We argue that to the extent that Chinese firms have been deeply embedded in China’s informal institutions, they are less responsive to formal institutional changes than Western firms operating in China. Using the major China patent law reform of 2001 as an exogenous event, we find results consistent with our key arguments: With the strengthening of the previously weak (utility model) patent protection, Chinese firms are less likely to apply for such patents to safeguard their innovations than Western firms. However, this difference becomes less pronounced in regions with higher quality intellectual property rights and legal institutions that foster research and development and innovation, and when Western firms gain longer operational experience in China. This study advances our understanding of the intricate interaction between formal and informal institutions and specifically how “stickiness” may arise in their substitutive relationship because of the embeddedness of firms in informal institutional environments. It also provides important implications for policy and innovation strategies for policy makers and firms in emerging economies. </jats:p

Assessing Social Text Placement in Mixed Reality TV

TV experiences are often social, be it at-a-distance (through text) or in-person (through speech). Mixed Reality (MR) headsets offer new opportunities to enhance social communication during TV viewing by placing social artifacts (e.g. text) anywhere the viewer wishes, rather than being constrained to a smartphone or TV display. In this paper, we use VR as a test-bed to evaluate different text locations for MR TV specifically. We introduce the concepts of wall messages, below-screen messages, and egocentric messages in addition to state-of-the-art on-screen messages (i.e., subtitles) and controller messages (i.e., reading text messages on the mobile device) to convey messages to users during TV viewing experiences. Our results suggest that a) future MR systems that aim to improve viewers’ experience need to consider the integration of a communication channel that does not interfere with viewers’ primary task, that is watching TV, and b) independent of the location of text messages, users prefer to be in full control of them, especially when reading and responding to them. Our findings pave the way for further investigations towards social at-a-distance communication in Mixed Reality

Nna1 Mediates Purkinje Cell Dendritic Development via Lysyl Oxidase Propeptide and NF-κB Signaling

SummaryThe molecular pathways controlling cerebellar Purkinje cell dendrite formation and maturation are poorly understood. The Purkinje cell degeneration (pcd) mutant mouse is characterized by mutations in Nna1, a gene discovered in an axonal regenerative context, but whose actual function in development and disease is unknown. We found abnormal development of Purkinje cell dendrites in postnatal pcdSid mice and linked this deficit to a deletion mutation in exon 7 of Nna1. With single cell gene profiling and virus-based gene transfer, we analyzed a molecular pathway downstream to Nna1 underlying abnormal Purkinje cell dendritogenesis in pcdSid mice. We discovered that mutant Nna1 dramatically increases intranuclear localization of lysyl oxidase propeptide, which interferes with NF-κB RelA signaling and microtubule-associated protein regulation of microtubule stability, leading to underdevelopment of Purkinje cell dendrites. These findings provide insight into Nna1's role in neuronal development and why its absence renders Purkinje cells more vulnerable

Manipulating infrared photons using plasmons in transparent graphene superlattices

Superlattices are artificial periodic nanostructures which can control the flow of electrons. Their operation typically relies on the periodic modulation of the electric potential in the direction of electron wave propagation. Here we demonstrate transparent graphene superlattices which can manipulate infrared photons utilizing the collective oscillations of carriers, i.e., plasmons of the ensemble of multiple graphene layers. The superlattice is formed by depositing alternating wafer-scale graphene sheets and thin insulating layers, followed by patterning them all together into 3-dimensional photonic-crystal-like structures. We demonstrate experimentally that the collective oscillation of Dirac fermions in such graphene superlattices is unambiguously nonclassical: compared to doping single layer graphene, distributing carriers into multiple graphene layers strongly enhances the plasmonic resonance frequency and magnitude, which is fundamentally different from that in a conventional semiconductor superlattice. This property allows us to construct widely tunable far-infrared notch filters with 8.2 dB rejection ratio and terahertz linear polarizers with 9.5 dB extinction ratio, using a superlattice with merely five graphene atomic layers. Moreover, an unpatterned superlattice shields up to 97.5% of the electromagnetic radiations below 1.2 terahertz. This demonstration also opens an avenue for the realization of other transparent mid- and far-infrared photonic devices such as detectors, modulators, and 3-dimensional meta-material systems.Comment: under revie

Excess Imidacloprid Exposure Causes the Heart Tube Malformation of Chick Embryos

As a neonicotinoid pesticide, imidacloprid is widely used to control sucking insects on agricultural planting and fleas on domestic animals. However, the extent to which imidacloprid exposure has an influence on cardiogensis in early embryogenesis is still poorly understood. In vertebrates, the heart is the first organ to be formed. In this study to address whether or not imidacloprid exposure affects early heart development, the early chick embryo has been used as an experimental model because of the accessibility of chick embryo at its early developmental stage. The results demonstrate that exposure of the early chick embryo to imidacloprid caused malformation of heart tube. Furthermore，the data reveal that down-regulation of GATA4, Nkx2.5 and BMP4 and up-regulation of Wnt3a led to aberrant cardiomyocyte differentiation. In addition, imidacloprid exposure interfered with basement membrane (BM) breakdown, E-cadherin/Laminin expression and mesoderm formation during the epithelial-mesenchymal transition (EMT) in gastrula chick embryos. Finally, the DiI-labeled cell migration trajectory indicated that imidacloprid restricted the cell migration of cardiac progenitors to primary heart field in gastrula chick embryos. A similar observation was also obtained from the cell migration assay of scratch wounds in vitro. Additionally, imidacloprid exposure negatively affected the cytoskeleton structure and expression of corresponding adhesion molecules. Taken together, these results reveal that the improper EMT, cardiac progenitor migration and differentiation are responsible for imidacloprid exposure-induced malformation of heart tube during chick embryo development

Mid-infrared plasmons in scaled graphene nanostructures

Plasmonics takes advantage of the collective response of electrons to electromagnetic waves, enabling dramatic scaling of optical devices beyond the diffraction limit. Here, we demonstrate the mid-infrared (4 to 15 microns) plasmons in deeply scaled graphene nanostructures down to 50 nm, more than 100 times smaller than the on-resonance light wavelength in free space. We reveal, for the first time, the crucial damping channels of graphene plasmons via its intrinsic optical phonons and scattering from the edges. A plasmon lifetime of 20 femto-seconds and smaller is observed, when damping through the emission of an optical phonon is allowed. Furthermore, the surface polar phonons in SiO2 substrate underneath the graphene nanostructures lead to a significantly modified plasmon dispersion and damping, in contrast to a non-polar diamond-like-carbon (DLC) substrate. Much reduced damping is realized when the plasmon resonance frequencies are close to the polar phonon frequencies. Our study paves the way for applications of graphene in plasmonic waveguides, modulators and detectors in an unprecedentedly broad wavelength range from sub-terahertz to mid-infrared.Comment: submitte

Oxidation resistance of graphene-coated Cu and Cu/Ni alloy

The ability to protect refined metals from reactive environments is vital to many industrial and academic applications. Current solutions, however, typically introduce several negative effects, including increased thickness and changes in the metal physical properties. In this paper, we demonstrate for the first time the ability of graphene films grown by chemical vapor deposition to protect the surface of the metallic growth substrates of Cu and Cu/Ni alloy from air oxidation. SEM, Raman spectroscopy, and XPS studies show that the metal surface is well protected from oxidation even after heating at 200 \degree C in air for up to 4 hours. Our work further shows that graphene provides effective resistance against hydrogen peroxide. This protection method offers significant advantages and can be used on any metal that catalyzes graphene growth