Bioinspired Nanomaterials: Self Stiffening Artificial Muscles

Cytoskeletal organization and elasticity are greatly influenced by molecular stiffness and sterics as well as externally imposed and internally generated stresses or so it might be hypothesized. These dynamic networks are generally composed of stiff filaments of actin and flexible crosslinkers. Recent experiments have identified not only isotropic, nematic and raft phases of such structures but also affine and non-affine elastic regimes of protein-crosslinked actin networks. Synthetic materials lack the complexity of biological tissues, and man-made materials that respond to external stresses through a permanent increase in stiffness are uncommon. Here we report for the first time, the systems of nanotube-polydimethyl siloxane(CNT-PDMS) soft nanocomposite and analogous liquid crystalline elastomer (LCE) that mimic the actin filaments in muscle tissues. Polydomain nematic LCEs increase in stiffness by up to 90% when subjected to a low amplitude (5%), repetitive dynamic compression. Elastomer stiffening is influenced by liquid crystal content, the presence of a nematic liquid crystal phase and the use of a dynamic as opposed to static deformation. Rheological and X-ray diffraction measurements reveal that the stiffening can be attributed to a mobile nano-scale nematic director that rotates in response to dynamic compression. Dynamic stiffening, not previously observed in liquid crystal elastomers may pave the way for useful development of self-healing materials and for the development of biocompatible, adaptive materials for tissue replacement

Implications of overestimated anthropogenic CO2 emissions on East Asian and global land CO2 flux inversion

Measurement and modelling of regional or country-level carbon dioxide (CO2) fluxes are becoming critical for verification of the greenhouse gases emission control. One of the commonly adopted approaches is inverse modelling, where CO2 fluxes (emission: positive flux, sink: negative flux) from the terrestrial ecosystems are estimated by combining atmospheric CO2 measurements with atmospheric transport models. The inverse models assume anthropogenic emissions are known, and thus the uncertainties in the emissions introduce systematic bias in estimation of the terrestrial (residual) fluxes by inverse modelling. Here we show that the CO2 sink increase, estimated by the inverse model, over East Asia (China, Japan, Korea and Mongolia), by about 0.26 PgC yr-1 (1 Pg = 1012 g) during 2001-2010, is suggested as an artifact of the anthropogenic CO2 emissions increasing too quickly in China by 1.41 PgC yr-1. Independent results from methane (CH4) inversion suggested about 41% lower rate of East Asian CH4 emission increase during 2002-2012. We apply a scaling factor of 0.59, based on CH4 inversion, to the rate of anthropogenic CO2 emission increase since the anthropogenic emissions of both CO2 and CH4 increase linearly in the emission inventory. We find no systematic increase in land CO2 uptake over East Asia during 1993-2010 or 2000-2009 when scaled anthropogenic CO2 emissions are used, and that there is a need of higher emission increase rate for 2010-2012 compared to those calculated by the inventory methods. High bias in anthropogenic CO2 emissions leads to stronger land sinks in global land-ocean flux partitioning in our inverse model. The corrected anthropogenic CO2 emissions also produce measurable reductions in the rate of global land CO2 sink increase post-2002, leading to a better agreement with the terrestrial biospheric model simulations that include CO2-fertlization and climate effects

Finite Element Simulation of Machining of Inconel 825, a Nickel Based Superalloy

Machining of nickel based super-alloys has gained a lot of importance in the last decade or so owing to their applications in areas like power generation (gas turbine), military aircrafts, marine propulsion and nuclear reactors. However, during high speed machining it faces a lot of problems in regard to thermal stress, and strain hardening, leading to premature tool failure. Use of cooling lubricants has declined in popularity because they pose a lot of problem with regards to their disposal, reuse and environmental safety. As a result coated tools have come into picture which improve the tool life in case of dry machining and increase productivity owing to their high thermal stability and integrity. Inconel 825 is a relatively newer grade of nickel bases super-alloys, on which a few tests have only been done. An attempt has been made to study the temperature and stress behaviour of tool insert, which in this case is taken as SNMG 120408 with respect to turning operation performed on Inconel 825 superalloy. The tool tip temperatures were found out and the temperature profiles were plotted for various feed and cutting speeds. Initial principal stress induced on the tool is also calculated. The variation of tool tip temperature and effective stress with respect to different cutting conditions were analysed and justified with respect to known knowledge. Comparative study has also been made between the uncoated tool and a CVD coated tool for the same cutting conditions

Modelling of greenhouse gases and related species in the Arctic environment

GRENE北極気候変動研究事業研究成果報告会日時：2016年3月3日（木）10：00-17：30会場：国立国語研究所　2F講

Mechanical Properties of Novel Bionanocomposites

In the present communication, a study on the synthesis and mechanical properties of a new series of green natural resins based bionanocomposites consisting of acacia, almond, neem and drumstick as resins with nano silica and nanosized calcium oxide as reinforcing fillers has been reported. Mechanical properties such as tensile, shear, adhesive and wear properties were investigated. Present work reveals that mechanical properties such as tensile strength, water resistance and wear resistance of bionanocomposites increases to considerable extent when reinforced with Nano powders of calcium oxide and silicon dioxide. These results are compared with the epoxy resin based nanocomposites. The bionanocomposites have potential to have widespread bioengineering applications

Efficient Use of Bio-Inspired Nanofabrication in Soft Electronics

Self-assembly plays an important role in the formation of different nanostructures either organic or inorganic. Controlled assembly of molecules into higher ordered hierarchical structures on the other hand require a thorough insight into the interactive forces that lie behind such an assembly. The interface between organic and inorganic materials is thus of primary significance when it comes to the tasks of selective deposition and assembly of inorganic molecules through organic agents. One of the bacterial species that belong to the class α-proteobacteria called Magnetospirillum magneticum (classified as AMB-1) is investigated in this study and it is found that this species is able to fulfill the requirements that are imposed by the complexity of the selective deposition and controlled assembly tasks. AMB-1 contain single-domain crystals of magnetite (Fe3O4) called magnetosomes that sense the external magnetic field that is further utilized for cellular displacement (magnetotaxis) through lash-like cellular appendages called flagella. The two flagella located at the proximal and distal ends of the cell consists of a protein monomer flagellin. Individual flagellin in turn that are located on the periphery of each of the flagellum's central channel consists of four sub-domains, two inner domains (D0, D1) made up of alpha helices and two outer domains (D2, D3) made up of beta sheets. However, it is the domain D3 that is exposed to the surrounding micro-environment, thereby interacting with the components to be selectively deposited, in this case, carbon nanotubes (CNT). Based on the electromagnetic and molecular dynamics simulations and the real-time experimental analysis involving optical microscopy utilizing 50 micron diameter conductor (44AWG) magnetic coils as directional magnetic field generation centers to visualize the motion of free as well as loaded AMB-1 as well as electron microscopy (TEM & SEM) to analyze the interactive forces between CNT and AMB-1 flagellum, it is found that once the domain D3 is functionalized with either metallic (m-) or semiconducting (s-) carbon nanotubes (CNT), the AMB-1 cell can be used as an efficient carrier for selective deposition tasks. Two aspects that are of particular interest are the phenomenal control of direction exhibited by AMB-1 using locally generated magnetic field and the efficient interactive forces in the form of short range forces (van der Waals, hydrophobic interactions and hydrogen bonds) and long range forces (electrostatic interactions) between m-CNT or s-CNT and D3. Thus, it is recognized that a compound semiconductor manufacturing technology involving bacterial carriers and carbon-based materials such as carbon nanotubes would be a desirable choice in the future

Fabrication of Graphene Oxide Nanofibrous Thin Film using Electrojet Spraying

Graphene oxide (GO) is a promising material with excellent properties. The GO has an aromatic lattice sheets of graphene with multi oxygen functional groups, such as ketone, carboxyl, and carbonyl groups. The addition of these groups is resulting from an oxidation treatment of the graphene. Go has the ability to exfoliate in many solvents and disperse in the water. Hummers method is an improved way to synthesize the GO because no toxic gas forms in yield. It is a reversible material, so the graphite can be restored from the GO within electrochemical reduction. The advantage of the GO gives it the chance to take a part of various applications. The electrical and the mechanical are the main fields for the GO. Many groups made films and nanofibers of GO by using a combination of GO with other substances like, solvents or polymers to enhance the viscosity of the GO1. The aim of this work is to form the GO nanofibers from it owns film, which means self-assembly of the GO nanofibers. Furthermore, the GO which been used is pure. Two different techniques have been followed to overcome the viscosity issue of the GO. Electrospinning for the GO solution preformed as the first method. In this method the potential difference between the syringe and the collector causing an electric filed to draw the solution and form the fibers. The second method was vacuum filtration where the vacuum is used to absorb all the liquids and leave the GO over the filter to get fibers. These GO thin films can be used in plethora or applications such as energy storage, water and like solution filtration, oil and water separations and many more

Molecular Dynamic Simulations of CRISPR and HIV

In the United States, there were 37,600 new HIV infections in 2014, with an estimated 1.1 million people living with the disease in 2015, according to the CDC. HIV targets the cell receptor CD4 and chemocine coreceptors CCR5 or CXCR5. Some individuals possess a mutation within CCR5 that causes a resistance to HIV-1. One HIV+ patient in Berlin, Timothy Brown, developed an immunity to the virus after a bone marrow transplant from a donor who possessed this CCR5 mutation. After this coincidence, researchers attempted a variety of gene therapies, such as zinc finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs), and Cas9. CRISPR/Cas9 is a promising new tool that scientists have been using to do direct editing of genomes with more ease and specificity than ever before. CRISPR stands for cluster of regularly interspaced palindromic repeats, which are segments of RNA that are found in many prokaryotes to defend the organism against viral infections and unwanted gene transfers. Cas is a gene cluster that mediates the response to the RNA encoded in the CRISPR segments. Cas are designated by the protein complex responsible for interference. Together, these molecules identify a segment of target RNA, extract it, and replace it with another segment. They make up part of the adaptive immune system of eukaryotic cells. This research hopes to create a predictive model by analyzing the existing gene therapy data from previous studies, and using numerical molecular dynamic simulation software to glean more information about those results. Previously published studies discuss how gene therapies such as ZFN and CRISPR are used to modify either the host genome or the viral genome3, and then experiments are performed to determine whether this therapy is effective at preventing viral infection. By analyzing the bonding characteristics of different strands of RNA, it may be possible to predict which RNA segments make the best candidates for gene therapies that will confer resistance to HIV infection

Piezoelectric Materials Based Scaffolds Fabrication for Cardiamyocyets Cell Growth

Tissue engineering is concerned on the growth of tissue making organs for implantation back to the donor himself. Instead of using organs transplantation and expose the patient for immunological rejection possibility, implantation is another alternative approach. Artificial scaffolds have to be fabricated base on the targeted organ. The projected scaffolds should have designed shapes with a suitable mechanical toughness, wettability, porosity, biodegradability and biocompatibility. Ideally, the projected scaffold should also allow imitating of the normal cell microenvironment in order to produce a tissue with the same biological functions as found in a body. Cardiomyocytes or cardiac myocytes required specific type of scaffold and in this work we developed a pattern of polyvinylidene fluoride (PVDF), a piezoelectric, fluoropolymer, and a highly non-reactive using electro spinning to form a nanoscale fibers from a liquid as a concept of energy harvesting from heart beating using piezoelectric material. Three different polymer solutions were made using 15%, 12% and 10% of PVDF each in DMF under specific condition and quantities. The second part of this experimental work is to fabricate the PVDF nanofibers from polymer solutions in the presence of conductive graphene nanoplateletes under specific condition and quantities. All produced nanofibers will be characterized and compared using X-ray diffraction (XRD), Electrochemical Impedance Spectroscopy (EIS) and Dynamic Mechanical Analyzer (DMA) for choosing optimal fibers

Carbon Nanotubes Modified for Cellular Membrane Integration

In this examination, we create a functionalized type of carbon nanotube with detergent molecules designed to integrate with cellular membranes via an attractive electrical force between our molecular construct and the membrane itself. Upon examination, the functionality of our construct shows a bond between the carbon nanotube and the detergent molecules. Hopefully opening the door to more advanced studies of cellular interactions