Determination of the nano-scaled contact area of staphylococcal cells.

PubMed

Spengler, Christian; Thewes, Nicolas; Jung, Philipp; Bischoff, Markus; Jacobs, Karin

2017-07-20

Bacterial adhesion is a crucial step during the development of infections as well as the formation of biofilms. Hence, fundamental research of bacterial adhesion mechanisms is of utmost importance. So far, less is known about the size of the contact area between bacterial cells and a surface. This gap will be filled by this study using a single-cell force spectroscopy-based method to investigate the contact area between a single bacterial cell of Staphylococcus aureus and a solid substrate. The technique relies on the strong influence of the hydrophobic interaction on bacterial adhesion: by incrementally crossing a very sharp hydrophobic/hydrophilic interface while performing force-distance curves with a single bacterial probe, the bacterial contact area can be determined. Assuming circular contact areas, their radii - determined in our experiments - are in the range from tens of nanometers to a few hundred nanometers. The contact area can be slightly enlarged by a larger load force, yet does not resemble a Hertzian contact, rather, the enlargement is a property of the individual bacterial cell. Additionally, Staphylococcus carnosus has been probed, which is less adherent than S. aureus, yet both bacteria exhibit a similar contact area size. This corroborates the notion that the adhesive strength of bacteria is not a matter of contact area, but rather a matter of which and how many molecules of the bacterial species' cell wall form the contact. Moreover, our method of determining the contact area can be applied to other microorganisms and the results might also be useful for studies using nanoparticles covered with soft, macromolecular coatings.

Formation and anisotropic magnetoresistance of Co/Pt nano-contacts through aluminum oxide barrier

NASA Astrophysics Data System (ADS)

Al-Mahdawi, Muftah; Sahashi, Masashi

2014-01-01

We report on the observation of anisotropic magnetoresistance (AMR) in vertical asymmetric nano-contacts (NCs) made through AlOx nano-oxide layer (NOL) formed by ion-assisted oxidation method in the film stack of Co/AlOx-NOL/Pt. Analysis of NC formation was based on in situ conductive atomic force microscopy and transmission electron microscopy. Depending on the purity of NCs from Al contamination, we observed up to 29% AMR ratio at room temperature.

The silicon chip: A versatile micro-scale platform for micro- and nano-scale systems

NASA Astrophysics Data System (ADS)

Choi, Edward

Cutting-edge advances in micro- and nano-scale technology require instrumentation to interface with the external world. While technology feature sizes are continually being reduced, the size of experimentalists and their instrumentation do not mirror this trend. Hence there is a need for effective application-specific instrumentation to bridge the gap from the micro and nano-scale phenomena being studied to the comparative macro-scale of the human interfaces. This dissertation puts forward the idea that the silicon CMOS integrated circuit, or microchip in short, serves as an excellent platform to perform this functionality. The electronic interfaces designed for the semiconductor industry are particularly attractive as development platforms, and the reduction in feature sizes that has been a hallmark of the industry suggests that chip-scale instrumentation may be more closely coupled to the phenomena of interest, allowing finer control or improved measurement capabilities. Compatibility with commercial processes will further enable economies of scale through mass production, another welcome feature of this approach. Thus chip-scale instrumentation may replace the bulky, expensive, cumbersome-to-operate macro-scale prototypes currently in use for many of these applications. The dissertation examines four specific applications in which the chip may serve as the ideal instrumentation platform. These are nanorod manipulation, polypyrrole bilayer hinge microactuator control, organic transistor hybrid circuits, and contact fluorescence imaging. The thesis is structured around chapters devoted to each of these projects, in addition to a chapter on preliminary work on an RFID system that serves as a wireless interface model. Each of these chapters contains tools and techniques developed for chip-scale instrumentation, from custom scripts for automated layout and data collection to microfabrication processes. Implementation of these tools to develop systems for the

Method of producing exfoliated graphite, flexible graphite, and nano-scaled graphene platelets

DOEpatents

Zhamu, Aruna; Shi, Jinjun; Guo, Jiusheng; Jang, Bor Z.

2010-11-02

The present invention provides a method of exfoliating a layered material (e.g., graphite and graphite oxide) to produce nano-scaled platelets having a thickness smaller than 100 nm, typically smaller than 10 nm. The method comprises (a) dispersing particles of graphite, graphite oxide, or a non-graphite laminar compound in a liquid medium containing therein a surfactant or dispersing agent to obtain a stable suspension or slurry; and (b) exposing the suspension or slurry to ultrasonic waves at an energy level for a sufficient length of time to produce separated nano-scaled platelets. The nano-scaled platelets are candidate reinforcement fillers for polymer nanocomposites. Nano-scaled graphene platelets are much lower-cost alternatives to carbon nano-tubes or carbon nano-fibers.

"Nano" Scale Biosignatures and the Search for Extraterrestrial Life

NASA Technical Reports Server (NTRS)

Oehler, D. Z.; Robert, F.; Meibom, A.; Mostefaoui, S.; Selo, M.; Walter, M. R.; Sugitani, K.; Allwood, A.; Mimura, K.; Gibson, E. K.

2008-01-01

A critical step in the search for remnants of potential life forms on other planets lies in our ability to recognize indigenous fragments of ancient microbes preserved in some of Earth's oldest rocks. To this end, we are building a database of nano-scale chemical and morphological characteristics of some of Earth's oldest organic microfossils. We are primarily using the new technology of Nano-Secondary ion mass spectrometry (NanoSIMS) which provides in-situ, nano-scale elemental analysis of trace quantities of organic residues. The initial step was to characterize element composition of well-preserved, organic microfossils from the late Proterozoic (0.8 Ga) Bitter Springs Formation of Australia. Results from that work provide morphologic detail and nitrogen/carbon ratios that appear to reflect the well-established biological origin of these 0.8 Ga fossils.

Advances in nano-scaled biosensors for biomedical applications.

PubMed

Wang, Jianling; Chen, Guihua; Jiang, Hui; Li, Zhiyong; Wang, Xuemei

2013-08-21

Recently, a growing amount of attention has been focused on the utility of biosensors for biomedical applications. Combined with nanomaterials and nanostructures, nano-scaled biosensors are installed for biomedical applications, such as pathogenic bacteria monitoring, virus recognition, disease biomarker detection, among others. These nano-biosensors offer a number of advantages and in many respects are ideally suited to biomedical applications, which could be made as extremely flexible devices, allowing biomedical analysis with speediness, excellent selectivity and high sensitivity. This minireview discusses the literature published in the latest years on the advances in biomedical applications of nano-scaled biosensors for disease bio-marking and detection, especially in bio-imaging and the diagnosis of pathological cells and viruses, monitoring pathogenic bacteria, thus providing insight into the future prospects of biosensors in relevant clinical applications.

Printed Nano Cu and NiSi Contacts and Metallization for Solar Cell Modules

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carmody, Michael John

There has long been a desire to replace the front-side silver contacts in silicon solar cells. There are two driving forces to do this. First, silver is an expensive precious metal. Secondly, the process to use silver requires that it be formulated into screen print pastes that need a lead-containing glass frit, and the use of lead is forbidden in many parts of the world. Because of the difficulty in replacing these pastes and the attendant processes, lead exemptions have granted to solar cells. Copper has been the replacement metal of choice because it is significantly cheaper than silver andmore » is very close to silver in electrical conductivity. Using processes which do not use lead, obviates it as an environmental contaminant. However, copper cannot be in contact with the silicon of the cell since it migrates through the silicon and causes defects which severely damage the efficiency of the cell. Hence, a conductive barrier must be placed between the copper and silicon and nickel, and especially nickel silicide, have been shown to be materials of choice. However, nickel must be sputtered and annealed to create the nickel silicide barrier, and copper has either been sputtered or plated. All of these processes require expensive, specialized equipment and plating uses environmentally unfriendly chemicals. Therefore, Intrinsiq proposed using printed nano nickel silicide ink (which we had previously invented) and printed nano copper ink to create these electrodes and barriers. We found that nano copper ink could be readily printed and sintered under a reducing atmosphere to give highly conductive grids. We further showed that nano nickel silicide ink could be readily jetted into grids on top of the silicon cell. It could then be annealed to create a barrier. However, it was found that the combination of printed NiSi and printed Cu did not give contact resistivity good enough to produce efficient cells. Only plated copper on top of the printed NiSi gave useful

MD Simulation on Collision Behavior Between Nano-Scale TiO₂ Particles During Vacuum Cold Spraying.

PubMed

Yao, Hai-Long; Yang, Guan-Jun; Li, Chang-Jiu

2018-04-01

Particle collision behavior influences significantly inter-nano particle bonding formation during the nano-ceramic coating deposition by vacuum cold spraying (or aerosol deposition method). In order to illuminate the collision behavior between nano-scale ceramic particles, molecular dynamic simulation was applied to explore impact process between nano-scale TiO2 particles through controlling impact velocities. Results show that the recoil efficiency of the nano-scale TiO2 particle is decreased with the increase of the impact velocity. Nano-scale TiO2 particle exhibits localized plastic deformation during collision at low velocities, while it is intensively deformed by collision at high velocities. This intensive deformation promotes the nano-particle adhesion rather than rebounding off. A relationship between the adhesion energy and the rebound energy is established for the bonding formation of the nano-scale TiO2 particle. The adhesion energy required to the bonding formation between nano-scale ceramic particles can be produced by high velocity collision.

Plasmids for variable expression of proteins targeted to the mitochondrial matrix or intermembrane space.

PubMed

Newman, Laura E; Schiavon, Cara; Kahn, Richard A

2016-01-01

We describe the construction and uses of a series of plasmids for directing expression to varied levels of exogenous proteins targeted to the mitochondrial matrix or intermembrane space. We found that the level of protein expression achieved, the kinetics of expression and mitochondrial import, and half-life after import can each vary with the protein examined. These factors should be considered when directing localization of an exogenous protein to mitochondria for rescue, proteomics, or other approaches. We describe the construction of a collection of plasmids for varied expression of proteins targeted to the mitochondrial matrix or intermembrane space, using previously defined targeting sequences and strength CMV promoters. The limited size of these compartments makes them particularly vulnerable to artifacts from over-expression. We found that different proteins display different kinetics of expression and import that should be considered when analyzing results from this approach. Finally, this collection of plasmids has been deposited in the Addgene plasmid repository to facilitate the ready access and use of these tools.

Synthesis and characterization of Al & SiCp nano particles by non-contact ultrasonic assisted method

NASA Astrophysics Data System (ADS)

Swain, Pradyut Kumar; Das, Ratnakar; Sahoo, Ashok Kumar; Naik, Bikash; Padhi, Payodhar

2018-05-01

The present study deals with proper mixing of SiCp nano particle in the aluminum metal matrix in two stages of processing i.e. primary and secondary. During primary processing, the breaking of agglomeration of nano particles take place and these are mixed with liquid aluminum powder using high frequency(35kHz) mechanical vibration. But, during secondary processing, mixing of nano particles along with subsequent cooling take place using high frequency non contact ultrasonic method. The study also reveals that in the liquid metal nano particle were uniformly dispersed and the segregation of the particles near the grain boundaries is due to pushing of the nano particle during grain growth. The study was performed by taking aluminum as matrix and SiCp as reinforcement with weight fraction of 2% and 3% and SiCp particles sizes of 30nm each. Scanning electron microscopy(SEM) and X-ray diffraction(XRD) were conducted for characterization of nano composite material.

Plasmonic Nanostructures for Nano-Scale Bio-Sensing

PubMed Central

Chung, Taerin; Lee, Seung-Yeol; Song, Eui Young; Chun, Honggu; Lee, Byoungho

2011-01-01

The optical properties of various nanostructures have been widely adopted for biological detection, from DNA sequencing to nano-scale single molecule biological function measurements. In particular, by employing localized surface plasmon resonance (LSPR), we can expect distinguished sensing performance with high sensitivity and resolution. This indicates that nano-scale detections can be realized by using the shift of resonance wavelength of LSPR in response to the refractive index change. In this paper, we overview various plasmonic nanostructures as potential sensing components. The qualitative descriptions of plasmonic nanostructures are supported by the physical phenomena such as plasmonic hybridization and Fano resonance. We present guidelines for designing specific nanostructures with regard to wavelength range and target sensing materials. PMID:22346679

Method of producing carbon coated nano- and micron-scale particles

DOEpatents

Perry, W. Lee; Weigle, John C; Phillips, Jonathan

2013-12-17

A method of making carbon-coated nano- or micron-scale particles comprising entraining particles in an aerosol gas, providing a carbon-containing gas, providing a plasma gas, mixing the aerosol gas, the carbon-containing gas, and the plasma gas proximate a torch, bombarding the mixed gases with microwaves, and collecting resulting carbon-coated nano- or micron-scale particles.

Contact angle hysteresis and motion behaviors of a water nano-droplet on suspended graphene under temperature gradient

NASA Astrophysics Data System (ADS)

Foroutan, Masumeh; Fatemi, S. Mahmood; Esmaeilian, Farshad; Fadaei Naeini, Vahid; Baniassadi, Majid

2018-05-01

In the present work, the effect of temperature gradient on the behavior of a water nano-droplet resting on a suspended graphene was studied based on a non-equilibrium molecular dynamics simulation. The acquired results indicate that the applied temperature gradient to the suspended graphene drives the water nano-droplet to the colder region. The droplet accelerates its motion toward the cold reservoir as the temperature gradient is increased. In addition to the translational motion of the nano-droplet, the vortical motion of the water molecules was also observed. Contact angle analysis was also utilized to describe the directional motion of the nano-droplet. The translational motion of the droplet leads to the estimation of contact angle hysteresis through advancing and receding contact angles while the rotational motion resulted in the advancing and receding fronts being switched with one another through the simulation. The average displacement vector of the water molecules shows that parts of the droplet seem to stagnate while other parts rotate around them. The reason behind this particular behavior was studied based on interaction energy contours between a water molecule and the suspended graphene. The obtained data indicate that the rotational motion is in agreement with the migration of the water molecules to low interaction energy regions in order to avoid high interaction energy areas.

Osm1 facilitates the transfer of electrons from Erv1 to fumarate in the redox-regulated import pathway in the mitochondrial intermembrane space

PubMed Central

Neal, Sonya E.; Dabir, Deepa V.; Wijaya, Juwina; Boon, Cennyana; Koehler, Carla M.

2017-01-01

Prokaryotes have aerobic and anaerobic electron acceptors for oxidative folding of periplasmic proteins. The mitochondrial intermembrane space has an analogous pathway with the oxidoreductase Mia40 and sulfhydryl oxidase Erv1, termed the mitochondrial intermembrane space assembly (MIA) pathway. The aerobic electron acceptors include oxygen and cytochrome c, but an acceptor that can function under anaerobic conditions has not been identified. Here we show that the fumarate reductase Osm1, which facilitates electron transfer from fumarate to succinate, fills this gap as a new electron acceptor. In addition to microsomes, Osm1 localizes to the mitochondrial intermembrane space and assembles with Erv1 in a complex. In reconstitution studies with reduced Tim13, Mia40, and Erv1, the addition of Osm1 and fumarate completes the disulfide exchange pathway that results in Tim13 oxidation. From in vitro import assays, mitochondria lacking Osm1 display decreased import of MIA substrates, Cmc1 and Tim10. Comparative reconstitution assays support that the Osm1/fumarate couple accepts electrons with similar efficiency to cytochrome c and that the cell has strategies to coordinate expression of the terminal electron acceptors. Thus Osm1/fumarate is a new electron acceptor couple in the mitochondrial intermembrane space that seems to function in both aerobic and anaerobic conditions. PMID:28814504

Imaging magnetisation dynamics in nano-contact spin-torque vortex oscillators exhibiting gyrotropic mode splitting

NASA Astrophysics Data System (ADS)

Keatley, Paul Steven; Redjai Sani, Sohrab; Hrkac, Gino; Majid Mohseni, Seyed; Dürrenfeld, Philipp; Åkerman, Johan; Hicken, Robert James

2017-04-01

Nano-contact spin-torque vortex oscillators (STVOs) are anticipated to find application as nanoscale sources of microwave emission in future technological applications. Presently the output power and phase stability of individual STVOs are not competitive with existing oscillator technologies. Synchronisation of multiple nano-contact STVOs via magnetisation dynamics has been proposed to enhance the microwave emission. The control of device-to-device variations, such as mode splitting of the microwave emission, is essential if multiple STVOs are to be successfully synchronised. In this work a combination of electrical measurements and time-resolved scanning Kerr microscopy (TRSKM) was used to demonstrate how mode splitting in the microwave emission of STVOs was related to the magnetisation dynamics that are generated. The free-running STVO response to a DC current only was used to identify devices and bias magnetic field configurations for which single and multiple modes of microwave emission were observed. Stroboscopic Kerr images were acquired by injecting a small amplitude RF current to phase lock the free-running STVO response. The images showed that the magnetisation dynamics of a multimode device with moderate splitting could be controlled by the injected RF current so that they exhibit similar spatial character to that of a single mode. Significant splitting was found to result from a complicated equilibrium magnetic state that was observed in Kerr images as irregular spatial characteristics of the magnetisation dynamics. Such dynamics were observed far from the nano-contact and so their presence cannot be detected in electrical measurements. This work demonstrates that TRSKM is a powerful tool for the direct observation of the magnetisation dynamics generated by STVOs that exhibit complicated microwave emission. Characterisation of such dynamics outside the nano-contact perimeter permits a deeper insight into the requirements for optimal phase-locking of

Fabrication of micro/nano hierarchical structures with analysis on the surface mechanics

NASA Astrophysics Data System (ADS)

Jheng, Yu-Sheng; Lee, Yeeu-Chang

2016-10-01

Biomimicry refers to the imitation of mechanisms and features found in living creatures using artificial methods. This study used optical lithography, colloidal lithography, and dry etching to mimic the micro/nano hierarchical structures covering the soles of gecko feet. We measured the static contact angle and contact angle hysteresis to reveal the behavior of liquid drops on the hierarchical structures. Pulling tests were also performed to measure the resistance of movement between the hierarchical structures and a testing plate. Our results reveal that hierarchical structures at the micro-/nano-scale are considerably hydrophobic, they provide good flow characteristics, and they generate more contact force than do surfaces with micro-scale cylindrical structures.

Brillouin gain enhancement in nano-scale photonic waveguide

NASA Astrophysics Data System (ADS)

Nouri Jouybari, Soodabeh

2018-05-01

The enhancement of stimulated Brillouin scattering in nano-scale waveguides has a great contribution in the improvement of the photonic devices technology. The key factors in Brillouin gain are the electrostriction force and radiation pressure generated by optical waves in the waveguide. In this article, we have proposed a new scheme of nano-scale waveguide in which the Brillouin gain is considerably improved compared to the previously-reported schemes. The role of radiation pressure in the Brillouin gain was much higher than the role of the electrostriction force. The Brillouin gain strongly depends on the structural parameters of the waveguide and the maximum value of 12127 W-1 m-1 is obtained for the Brillouin gain.

Tribological study on rapeseed oil with nano-additives in close contact sliding situation

NASA Astrophysics Data System (ADS)

Gupta, Rajeev Nayan; Harsha, A. P.; Singh, Sagar

2018-02-01

The present work deals with the tribological evaluation of three types of nano-additives, i.e., copper oxide (CuO; ≈ 151.2 nm), cerium oxide (CeO2; ≈ 80 nm) and polytetrafluoroethylene (PTFE; ≈ 90.4 nm) with rapeseed oil under steel-steel sliding contacts. The nano-additives concentrations in the base oil were 0.1, 0.25 and 0.5% w/v for the lubricant formulation. Further, the rapeseed oil was also epoxidized by a chemical method and the tribological behavior was compared with the base oil (unmodified oil) at similar nano-additives concentrations. The ASTM standards were followed for the study of wear preventive and extreme-pressure analysis of nanolubricants, and it was carried out using four-ball tester. In the antiwear test, CeO2 and PTFE nano-additives have shown the significant reduction in the wear scar diameter at the concentration of 0.1% w/v. In the extreme-pressure test, 0.5% w/v concentration was optimum for oxide nanoparticles; however, PTFE nanoparticles did not show positive effect with both the base oils. Different characterization techniques were employed to confirm the oil modification and for the study of the worn surfaces.

Contact material optimization and contact physics in metal-contact microelectromechanical systems (MEMS) switches

NASA Astrophysics Data System (ADS)

Yang, Zhenyin

Metal-contact MEMS switches hold great promise for implementing agile radio frequency (RF) systems because of their small size, low fabrication cost, low power consumption, wide operational band, excellent isolation and exceptionally low signal insertion loss. Gold is often utilized as a contact material for metal-contact MEMS switches due to its excellent electrical conductivity and corrosion resistance. However contact wear and stiction are the two major failure modes for these switches due to its material softness and high surface adhesion energy. To strengthen the contact material, pure gold was alloyed with other metal elements. We designed and constructed a new micro-contacting test facility that closely mimic the typical MEMS operation and utilized this facility to efficiently evaluate optimized contact materials. Au-Ni binary alloy system as the candidate contact material for MEMS switches was systematically investigated. A correlation between contact material properties (etc. microstructure, micro-hardness, electrical resistivity, topology, surface structures and composition) and micro-contacting performance was established. It was demonstrated nano-scale graded two-phase Au-Ni film could possibly yield an improved device performance. Gold micro-contact degradation mechanisms were also systematically investigated by running the MEMS switching tests under a wide range of test conditions. According to our quantitative failure analysis, field evaporation could be the dominant failure mode for highfield (> critical threshold field) hot switching; transient thermal-assisted wear could be the dominant failure mode for low-field hot switching; on the other hand, pure mechanical wear and steady current heating (1 mA) caused much less contact degradation in cold switching tests. Results from low-force (50 muN/micro-contact), low current (0.1 mA) tests on real MEMS switches indicated that continuous adsorbed films from ambient air could degrade the switch contact

Multi-scale Modeling and Analysis of Nano-RFID Systems on HPC Setup

NASA Astrophysics Data System (ADS)

Pathak, Rohit; Joshi, Satyadhar

In this paper we have worked out on some the complex modeling aspects such as Multi Scale modeling, MATLAB Sugar based modeling and have shown the complexities involved in the analysis of Nano RFID (Radio Frequency Identification) systems. We have shown the modeling and simulation and demonstrated some novel ideas and library development for Nano RFID. Multi scale modeling plays a very important role in nanotech enabled devices properties of which cannot be explained sometimes by abstraction level theories. Reliability and packaging still remains one the major hindrances in practical implementation of Nano RFID based devices. And to work on them modeling and simulation will play a very important role. CNTs is the future low power material that will replace CMOS and its integration with CMOS, MEMS circuitry will play an important role in realizing the true power in Nano RFID systems. RFID based on innovations in nanotechnology has been shown. MEMS modeling of Antenna, sensors and its integration in the circuitry has been shown. Thus incorporating this we can design a Nano-RFID which can be used in areas like human implantation and complex banking applications. We have proposed modeling of RFID using the concept of multi scale modeling to accurately predict its properties. Also we give the modeling of MEMS devices that are proposed recently that can see possible application in RFID. We have also covered the applications and the advantages of Nano RFID in various areas. RF MEMS has been matured and its devices are being successfully commercialized but taking it to limits of nano domains and integration with singly chip RFID needs a novel approach which is being proposed. We have modeled MEMS based transponder and shown the distribution for multi scale modeling for Nano RFID.

Polycrystalline silicon carbide dopant profiles obtained through a scanning nano-Schottky contact

DOE Office of Scientific and Technical Information (OSTI.GOV)

Golt, M. C.; Strawhecker, K. E.; Bratcher, M. S.

2016-07-14

The unique thermo-electro-mechanical properties of polycrystalline silicon carbide (poly-SiC) make it a desirable candidate for structural and electronic materials for operation in extreme environments. Necessitated by the need to understand how processing additives influence poly-SiC structure and electrical properties, the distribution of lattice defects and impurities across a specimen of hot-pressed 6H poly-SiC processed with p-type additives was visualized with high spatial resolution using a conductive atomic force microscopy approach in which a contact forming a nano-Schottky interface is scanned across the sample. The results reveal very intricate structures within poly-SiC, with each grain having a complex core-rim structure. Thismore » complexity results from the influence the additives have on the evolution of the microstructure during processing. It was found that the highest conductivities localized at rims as well as at the interface between the rim and the core. The conductivity of the cores is less than the conductivity of the rims due to a lower concentration of dopant. Analysis of the observed conductivities and current-voltage curves is presented in the context of nano-Schottky contact regimes where the conventional understanding of charge transport to diode operation is no longer valid.« less

Polycrystalline silicon carbide dopant profiles obtained through a scanning nano-Schottky contact

NASA Astrophysics Data System (ADS)

Golt, M. C.; Strawhecker, K. E.; Bratcher, M. S.; Shanholtz, E. R.

2016-07-01

The unique thermo-electro-mechanical properties of polycrystalline silicon carbide (poly-SiC) make it a desirable candidate for structural and electronic materials for operation in extreme environments. Necessitated by the need to understand how processing additives influence poly-SiC structure and electrical properties, the distribution of lattice defects and impurities across a specimen of hot-pressed 6H poly-SiC processed with p-type additives was visualized with high spatial resolution using a conductive atomic force microscopy approach in which a contact forming a nano-Schottky interface is scanned across the sample. The results reveal very intricate structures within poly-SiC, with each grain having a complex core-rim structure. This complexity results from the influence the additives have on the evolution of the microstructure during processing. It was found that the highest conductivities localized at rims as well as at the interface between the rim and the core. The conductivity of the cores is less than the conductivity of the rims due to a lower concentration of dopant. Analysis of the observed conductivities and current-voltage curves is presented in the context of nano-Schottky contact regimes where the conventional understanding of charge transport to diode operation is no longer valid.

Nano-scale processes behind ion-beam cancer therapy

NASA Astrophysics Data System (ADS)

Surdutovich, Eugene; Garcia, Gustavo; Mason, Nigel; Solov'yov, Andrey V.

2016-04-01

This topical issue collates a series of papers based on new data reported at the third Nano-IBCT Conference of the COST Action MP1002: Nanoscale Insights into Ion Beam Cancer Therapy, held in Boppard, Germany, from October 27th to October 31st, 2014. The Nano-IBCT COST Action was launched in December 2010 and brought together more than 300 experts from different disciplines (physics, chemistry, biology) with specialists in radiation damage of biological matter from hadron-therapy centres, and medical institutions. This meeting followed the first and the second conferences of the Action held in October 2011 in Caen, France and in May 2013 in Sopot, Poland respectively. This conference series provided a focus for the European research community and has highlighted the pioneering research into the fundamental processes underpinning ion beam cancer therapy. Contribution to the Topical Issue "COST Action Nano-IBCT: Nano-scale Processes Behind Ion-Beam Cancer Therapy", edited by Andrey V. Solov'yov, Nigel Mason, Gustavo Garcia and Eugene Surdutovich.

[Study on preparation of composite nano-scale Fe3O4 for phosphorus control].

PubMed

Li, Lei; Pan, Gang; Chen, Hao

2010-03-01

Composite nano-scale Fe3O4 particles were prepared in sodium carboxymethyl cellulose (CMC) solution by the oxidation deposition method. The adsorptions of phosphorus by micro-scale Fe3O4 and composite nano-scale Fe3O4 were investigated in water and soil, and the role of cellulase in the adsorption of composite nano-scale Fe3O4 was studied. Kinetic tests indicated that the equilibrium adsorption capacity of phosphorous on the composite nano-scale Fe3O4 (2.1 mg/g) was less than that of micro-scale Fe3O4 (3.2 mg/g). When cellulase was added to the solution of composite nano-scale Fe3O4 to degrade CMC, the removal rate of P by the nanoparticles (86%) was enhanced to the same level as the microparticles (90%). In the column tests, when the composite nano-scale Fe3O4 suspension was introduced in the downflow mode through the soil column, 72% of Fe3O4 penetrated through the soil bed under gravity. In contrast, the micro-scale Fe3O4 failed to pass through the soil column. The retention rate of P was 45% in the soil column when treated by the CMC-stabilized nanoparticles, in comparison with only 30% for the untreated soil column, however it could be improved to 74% in the soil column when treated by both the CMC-stabilized nanoparticles and cellulase, which degraded CMC after the nanoparticles were delivered into the soil.

Intelligent Design of Nano-Scale Molecular Imaging Agents

PubMed Central

Kim, Sung Bae; Hattori, Mitsuru; Ozawa, Takeaki

2012-01-01

Visual representation and quantification of biological processes at the cellular and subcellular levels within living subjects are gaining great interest in life science to address frontier issues in pathology and physiology. As intact living subjects do not emit any optical signature, visual representation usually exploits nano-scale imaging agents as the source of image contrast. Many imaging agents have been developed for this purpose, some of which exert nonspecific, passive, and physical interaction with a target. Current research interest in molecular imaging has mainly shifted to fabrication of smartly integrated, specific, and versatile agents that emit fluorescence or luminescence as an optical readout. These agents include luminescent quantum dots (QDs), biofunctional antibodies, and multifunctional nanoparticles. Furthermore, genetically encoded nano-imaging agents embedding fluorescent proteins or luciferases are now gaining popularity. These agents are generated by integrative design of the components, such as luciferase, flexible linker, and receptor to exert a specific on–off switching in the complex context of living subjects. In the present review, we provide an overview of the basic concepts, smart design, and practical contribution of recent nano-scale imaging agents, especially with respect to genetically encoded imaging agents. PMID:23235326

Intelligent design of nano-scale molecular imaging agents.

PubMed

Kim, Sung Bae; Hattori, Mitsuru; Ozawa, Takeaki

2012-12-12

Visual representation and quantification of biological processes at the cellular and subcellular levels within living subjects are gaining great interest in life science to address frontier issues in pathology and physiology. As intact living subjects do not emit any optical signature, visual representation usually exploits nano-scale imaging agents as the source of image contrast. Many imaging agents have been developed for this purpose, some of which exert nonspecific, passive, and physical interaction with a target. Current research interest in molecular imaging has mainly shifted to fabrication of smartly integrated, specific, and versatile agents that emit fluorescence or luminescence as an optical readout. These agents include luminescent quantum dots (QDs), biofunctional antibodies, and multifunctional nanoparticles. Furthermore, genetically encoded nano-imaging agents embedding fluorescent proteins or luciferases are now gaining popularity. These agents are generated by integrative design of the components, such as luciferase, flexible linker, and receptor to exert a specific on-off switching in the complex context of living subjects. In the present review, we provide an overview of the basic concepts, smart design, and practical contribution of recent nano-scale imaging agents, especially with respect to genetically encoded imaging agents.

Spontaneous imbibition in fractal tortuous micro-nano pores considering dynamic contact angle and slip effect: phase portrait analysis and analytical solutions.

PubMed

Li, Caoxiong; Shen, Yinghao; Ge, Hongkui; Zhang, Yanjun; Liu, Tao

2018-03-02

Shales have abundant micro-nano pores. Meanwhile, a considerable amount of fracturing liquid is imbibed spontaneously in the hydraulic fracturing process. The spontaneous imbibition in tortuous micro-nano pores is special to shale, and dynamic contact angle and slippage are two important characteristics. In this work, we mainly investigate spontaneous imbibition considering dynamic contact angle and slip effect in fractal tortuous capillaries. We introduce phase portrait analysis to analyse the dynamic state and stability of imbibition. Moreover, analytical solutions to the imbibition equation are derived under special situations, and the solutions are verified by published data. Finally, we discuss the influences of slip length, dynamic contact angle and gravity on spontaneous imbibition. The analysis shows that phase portrait is an ideal tool for analysing spontaneous imbibition because it can evaluate the process without solving the complex governing ordinary differential equations. Moreover, dynamic contact angle and slip effect play an important role in fluid imbibition in fractal tortuous capillaries. Neglecting slip effect in micro-nano pores apparently underestimates imbibition capability, and ignoring variations in contact angle causes inaccuracy in predicting imbibition speed at the initial stage of the process. Finally, gravity is one of the factors that control the stabilisation of the imbibition process.

In situ thermomechanical testing methods for micro/nano-scale materials.

PubMed

Kang, Wonmo; Merrill, Marriner; Wheeler, Jeffrey M

2017-02-23

The advance of micro/nanotechnology in energy-harvesting, micropower, electronic devices, and transducers for automobile and aerospace applications has led to the need for accurate thermomechanical characterization of micro/nano-scale materials to ensure their reliability and performance. This persistent need has driven various efforts to develop innovative experimental techniques that overcome the critical challenges associated with precise mechanical and thermal control of micro/nano-scale specimens during material characterization. Here we review recent progress in the development of thermomechanical testing methods from miniaturized versions of conventional macroscopic test systems to the current state of the art of in situ uniaxial testing capabilities in electron microscopes utilizing either indentation-based microcompression or integrated microsystems. We discuss the major advantages/disadvantages of these methods with respect to specimen size, range of temperature control, ease of experimentation and resolution of the measurements. We also identify key challenges in each method. Finally, we summarize some of the important discoveries that have been made using in situ thermomechanical testing and the exciting research opportunities still to come in micro/nano-scale materials.

Preparation of biomimetic nano-structured films with multi-scale roughness

NASA Astrophysics Data System (ADS)

Shelemin, A.; Nikitin, D.; Choukourov, A.; Kylián, O.; Kousal, J.; Khalakhan, I.; Melnichuk, I.; Slavínská, D.; Biederman, H.

2016-06-01

Biomimetic nano-structured films are valuable materials in various applications. In this study we introduce a fully vacuum-based approach for fabrication of such films. The method combines deposition of nanoparticles (NPs) by gas aggregation source and deposition of overcoat thin film that fixes the nanoparticles on a surface. This leads to the formation of nanorough surfaces which, depending on the chemical nature of the overcoat, may range from superhydrophilic to superhydrophobic. In addition, it is shown that by proper adjustment of the amount of NPs it is possible to tailor adhesive force on superhydrophobic surfaces. Finally, the possibility to produce NPs in a wide range of their size (45-240 nm in this study) makes it possible to produce surfaces not only with single scale roughness, but also with bi-modal or even multi-modal character. Such surfaces were found to be superhydrophobic with negligible water contact angle hysteresis and hence truly slippery.

Multi scale modeling of ignition and combustion of micro and nano aluminum particles

NASA Astrophysics Data System (ADS)

Puri, Puneesh

With renewed interest in nano scale energetic materials like aluminum, many fundamental issues concerning the ignition and combustion characteristics at nano scales, remain to be clarified. The overall aim of the current study is the establishment of a unified theory accommodating the various processes and mechanisms involved in the combustion and ignition of aluminum particles at micro and nano scales. A comprehensive review on the ignition and combustion of aluminum particles at multi scales was first performed identifying various processes and mechanisms involved. Research focus was also placed on the establishment of a Molecular Dynamics (MD) simulation tool to investigate the characteristics of nano-particulate aluminum through three major studies. The general computational framework involved parallelized preprocessing, post-processing and main code with capability to simulate different ensembles using appropriate algorithms. Size dependence of melting temperature of pure aluminum particles was investigated in the first study. Phenomena like dynamic coexistence of solid and liquid phase and effect of surface charges on melting were explored. The second study involved the study of effect of defects in the form of voids on melting of bulk and particulate phase aluminum. The third MD study was used to analyze the thermo-mechanical behavior of nano-sized aluminum particles with total diameter of 5-10 nm and oxide thickness of 1-2.5 nm. The ensuing solid-solid and solid-liquid phase changes in the core and shell, stresses developed within the shell, and the diffusion of aluminum cations in the oxide layer, were explored in depth for amorphous and crystalline oxide layers. In the limiting case, the condition for pyrophoricity/explosivity of nano-particulate aluminum was analyzed and modified. The size dependence of thermodynamic properties at nano scales were considered and incorporated into the existing theories developed for micro and larger scales. Finally, a

Fabrication of flower-like micro/nano dual scale structured copper oxide surfaces: Optimization of self-cleaning properties via Taguchi design

NASA Astrophysics Data System (ADS)

Moosavi, Saeideh Sadat; Norouzbeigi, Reza; Velayi, Elmira

2017-11-01

In the present work, copper oxide superhydrophobic surface is fabricated on a copper foil via the chemical bath deposition (CBD) method. The effects of some influential factors such as initial concentrations of Cu (II) ions and the surface energy modifier, solution pH, reaction and modification steps time on the wettability property of copper oxide surface were evaluated using Taguchi L16 experimental design. Results showed that the initial concentration of Cu (II) has the most significant impact on the water contact angle and wettability characteristics. The XRD, SEM, AFM and FTIR analyses were used to characterize the copper oxide surfaces. The Water contact angle (WCA) and contact angle hysteresis (CAH) were also measured. The SEM results indicated the formation of a flower-like micro/nano dual-scale structure of copper oxide on the substrate. This structure composed of numerous nano-petals with a thickness of about 50 nm. As a result, a copper oxide hierarchical surface with WCA of 168.4°± 3.5° and CAH of 2.73° exhibited the best superhydrophobicity under proposed optimum condition. This result has been obtained just by 10 min hydrolysis reaction. Besides, this surface showed a good stability under acidic and saline conditions.

Osm1 facilitates the transfer of electrons from Erv1 to fumarate in the redox-regulated import pathway in the mitochondrial intermembrane space.

PubMed

Neal, Sonya E; Dabir, Deepa V; Wijaya, Juwina; Boon, Cennyana; Koehler, Carla M

2017-10-15

Prokaryotes have aerobic and anaerobic electron acceptors for oxidative folding of periplasmic proteins. The mitochondrial intermembrane space has an analogous pathway with the oxidoreductase Mia40 and sulfhydryl oxidase Erv1, termed the mitochondrial intermembrane space assembly (MIA) pathway. The aerobic electron acceptors include oxygen and cytochrome c , but an acceptor that can function under anaerobic conditions has not been identified. Here we show that the fumarate reductase Osm1, which facilitates electron transfer from fumarate to succinate, fills this gap as a new electron acceptor. In addition to microsomes, Osm1 localizes to the mitochondrial intermembrane space and assembles with Erv1 in a complex. In reconstitution studies with reduced Tim13, Mia40, and Erv1, the addition of Osm1 and fumarate completes the disulfide exchange pathway that results in Tim13 oxidation. From in vitro import assays, mitochondria lacking Osm1 display decreased import of MIA substrates, Cmc1 and Tim10. Comparative reconstitution assays support that the Osm1/fumarate couple accepts electrons with similar efficiency to cytochrome c and that the cell has strategies to coordinate expression of the terminal electron acceptors. Thus Osm1/fumarate is a new electron acceptor couple in the mitochondrial intermembrane space that seems to function in both aerobic and anaerobic conditions. © 2017 Neal et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

Controlled crystallization and granulation of nano-scale β-Ni(OH) 2 cathode materials for high power Ni-MH batteries

NASA Astrophysics Data System (ADS)

He, Xiangming; Li, Jianjun; Cheng, Hongwei; Jiang, Changyin; Wan, Chunrong

A novel synthesis of controlled crystallization and granulation was attempted to prepare nano-scale β-Ni(OH) 2 cathode materials for high power Ni-MH batteries. Nano-scale β-Ni(OH) 2 and Co(OH) 2 with a diameter of 20 nm were prepared by controlled crystallization, mixed by ball milling, and granulated to form about 5 μm spherical grains by spray drying granulation. Both the addition of nano-scale Co(OH) 2 and granulation significantly enhanced electrochemical performance of nano-scale Ni(OH) 2. The XRD and TEM analysis shown that there were a large amount of defects among the crystal lattice of as-prepared nano-scale Ni(OH) 2, and the DTA-TG analysis shown that it had both lower decomposition temperature and higher decomposition reaction rate, indicating less thermal stability, as compared with conventional micro-scale Ni(OH) 2, and indicating that it had higher electrochemical performance. The granulated grains of nano-scale Ni(OH) 2 mixed with nano-scale Co(OH) 2 at Co/Ni = 1/20 presented the highest specific capacity reaching its theoretical value of 289 mAh g -1 at 1 C, and also exhibited much improved electrochemical performance at high discharge capacity rate up to 10 C. The granulated grains of nano-scale β-Ni(OH) 2 mixed with nano-scale Co(OH) 2 is a promising cathode active material for high power Ni-MH batteries.

Nano-scaled top-down of bismuth chalcogenides based on electrochemical lithium intercalation

NASA Astrophysics Data System (ADS)

Chen, Jikun; Zhu, Yingjie; Chen, Nuofu; Liu, Xinling; Sun, Zhengliang; Huang, Zhenghong; Kang, Feiyu; Gao, Qiuming; Jiang, Jun; Chen, Lidong

2011-12-01

A two-step method has been used to fabricate nano-particles of layer-structured bismuth chalcogenide compounds, including Bi2Te3, Bi2Se3, and Bi2Se0.3Te2.7, through a nano-scaled top-down route. In the first step, lithium (Li) atoms are intercalated between the van der Waals bonded quintuple layers of bismuth chalcogenide compounds by controllable electrochemical process inside self-designed lithium ion batteries. And in the second step, the Li intercalated bismuth chalcogenides are subsequently exposed to ethanol, in which process the intercalated Li atoms would explode like atom-scaled bombs to exfoliate original microscaled powder into nano-scaled particles with size around 10 nm. The influence of lithium intercalation speed and amount to three types of bismuth chalcogenide compounds are compared and the optimized intercalation conditions are explored. As to maintain the phase purity of the final nano-particle product, the intercalation lithium amount should be well controlled in Se contained bismuth chalcogenide compounds. Besides, compared with binary bismuth chalcogenide compound, lower lithium intercalation speed should be applied in ternary bismuth chalcogenide compound.

Production of ultra-thin nano-scaled graphene platelets from meso-carbon micro-beads

DOEpatents

Zhamu, Aruna; Guo, Jiusheng; Jang, Bor Z

2014-11-11

A method of producing nano-scaled graphene platelets (NGPs) having an average thickness no greater than 50 nm, typically less than 2 nm, and, in many cases, no greater than 1 nm. The method comprises (a) intercalating a supply of meso-carbon microbeads (MCMBs) to produce intercalated MCMBs; and (b) exfoliating the intercalated MCMBs at a temperature and a pressure for a sufficient period of time to produce the desired NGPs. Optionally, the exfoliated product may be subjected to a mechanical shearing treatment, such as air milling, air jet milling, ball milling, pressurized fluid milling, rotating-blade grinding, or ultrasonicating. The NGPs are excellent reinforcement fillers for a range of matrix materials to produce nanocomposites. Nano-scaled graphene platelets are much lower-cost alternatives to carbon nano-tubes or carbon nano-fibers.

Characterization of Cr/6H-SiC(0 0 0 1) nano-contacts by current-sensing AFM

NASA Astrophysics Data System (ADS)

Grodzicki, Miłosz; Smolarek, Szymon; Mazur, Piotr; Zuber, Stefan; Ciszewski, Antoni

2009-11-01

The electrical properties and interface chemistry of Cr/6H-SiC(0 0 0 1) contacts have been studied by current-sensing atomic force microscopy (CS-AFM) and X-ray photoelectron spectroscopy (XPS). Cr layers were vapor deposited under ultrahigh vacuum onto both ex situ etched in H 2 and in situ Ar + ion-bombarded samples. The Cr/SiC contacts are electrically non-uniform. Both the measured I- V characteristics and the modeling calculations enabled to estimate changes of the Schottky barrier height caused by Ar + bombardment. Formation of ohmic nano-contacts on Ar +-bombarded surfaces was observed.

Characterization of Nano-scale Aluminum Oxide Transport through Porous Media

NASA Astrophysics Data System (ADS)

Norwood, S.; Reynolds, M.; Miao, Z.; Brusseau, M. L.; Johnson, G. R.

2011-12-01

Colloidal material (including that in the nanoparticle size range) is naturally present in most subsurface environments. Mobilization of these colloidal materials via particle disaggregation may occur through abrupt changes in flow rate and/or via chemical perturbations, such as rapid changes in ionic strength or solution pH. While concentrations of natural colloidal materials in the subsurface are typically small, those concentrations may be greatly increased at contaminated sites such as following the application of metal oxides for groundwater remediation efforts. Additionally, while land application of biosolids has become common practice in the United States as an alternative to industrial fertilizers, biosolids have been shown to contain a significant fraction of organic and inorganic nano-scale colloidal materials such as oxides of iron, titanium, and aluminum. Given their reactivity and small size, there are many questions concerning the potential migration of nano-scale colloidal materials through the soil column and their potential participation in the facilitated transport of contaminants, such as heavy metals and emerging pollutants. The purpose of this study was to investigate the transport behavior of aluminum oxide (Al2O3) nanoparticles through porous media. The impacts of pH, ionic strength, pore-water velocity (i.e., residence time), and aqueous-phase concentration on transport was investigated. All experiments were conducted with large injection pulses to fully characterize the impact of long-term retention and transport behavior relevant for natural systems wherein multiple retention processes may be operative. The results indicate that the observed nonideal transport behavior of the nano-scale colloids is influenced by multiple retention mechanisms/processes. Given the ubiquitous nature of these nano-scale colloids in the environment, a clear understanding of their transport and fate is necessary in further resolving the potential for

Prevention of arterial graft spasm in rats using a vasodilator-eluting biodegradable nano-scaled fibre†

PubMed Central

Yagami, Kei; Yamawaki-Ogata, Aika; Satake, Makoto; Kaneko, Hiroaki; Oshima, Hideki; Usui, Akihiko; Ueda, Yuichi; Narita, Yuji

2013-01-01

OBJECTIVES Arterial graft spasm occasionally causes circulatory collapse immediately following coronary artery bypass graft. The aim of this study is to evaluate the efficacy of our developed materials, which were composed of milrinone (phosphodiesterase III inhibitor) or diltiazem (calcium-channel blocker), with nano-scaled fibre made of biodegradable polymer to prevent arterial spasm. METHODS Milrinone- or diltiazem-releasing biodegradable nano-scaled fibres were fabricated by an electrospinning procedure. In vivo milrinone- or diltiazem-releasing tests were performed to confirm the sustained release of the drugs. An in vivo arterial spasm model was established by subcutaneous injection of noradrenalin around the rat femoral artery. Rats were randomly divided into four groups as follows: those that received 5 mg of milrinone-releasing biodegradable nano-scaled fibre (group M, n = 14); 5 mg of diltiazem-releasing biodegradable nano-scaled fibre (group D, n = 12); or those that received fibre without drugs (as a control; group C, n = 14) implanted into the rat femoral artery. In the fourth group, sham operation was performed (group S, n = 10). One day after the implantation, noradrenalin was injected in all groups. The femoral arterial blood flow was measured continuously before and after noradrenalin injection. The maximum blood flow before noradrenalin injection and minimum blood flow after noradrenalin injection were measured. RESULTS In vivo drug-releasing test revealed that milrinone-releasing biodegradable nano-scaled fibre released 78% of milrinone and diltiazem-releasing biodegradable nano-scaled fibre released 50% diltiazem on the first day. The ratios of rat femoral artery blood flow after/before noradrenalin injection in groups M (0.74 ± 0.16) and D (0.72 ± 0.05) were significantly higher than those of groups C (0.54 ± 0.09) and S (0.55 ± 0.16) (P < 0.05). CONCLUSION Noradrenalin-induced rat femoral artery spasm was inhibited by the implantation of

Nicholas Metropolis Award for Outstanding Doctoral Thesis Work in Computational Physics Talk: Understanding Nano-scale Electronic Systems via Large-scale Computation

NASA Astrophysics Data System (ADS)

Cao, Chao

2009-03-01

Nano-scale physical phenomena and processes, especially those in electronics, have drawn great attention in the past decade. Experiments have shown that electronic and transport properties of functionalized carbon nanotubes are sensitive to adsorption of gas molecules such as H2, NO2, and NH3. Similar measurements have also been performed to study adsorption of proteins on other semiconductor nano-wires. These experiments suggest that nano-scale systems can be useful for making future chemical and biological sensors. Aiming to understand the physical mechanisms underlying and governing property changes at nano-scale, we start off by investigating, via first-principles method, the electronic structure of Pd-CNT before and after hydrogen adsorption, and continue with coherent electronic transport using non-equilibrium Green’s function techniques combined with density functional theory. Once our results are fully analyzed they can be used to interpret and understand experimental data, with a few difficult issues to be addressed. Finally, we discuss a newly developed multi-scale computing architecture, OPAL, that coordinates simultaneous execution of multiple codes. Inspired by the capabilities of this computing framework, we present a scenario of future modeling and simulation of multi-scale, multi-physical processes.

Formation and metrology of dual scale nano-morphology on SF(6) plasma etched silicon surfaces.

PubMed

Boulousis, G; Constantoudis, V; Kokkoris, G; Gogolides, E

2008-06-25

Surface roughness and nano-morphology in SF(6) plasma etched silicon substrates are investigated in a helicon type plasma reactor as a function of etching time and process parameters. The plasma etched surfaces are analyzed by atomic force microscopy. It is found that dual scale nano-roughness is formatted on the silicon surface comprising an underlying nano-roughness and superimposed nano-mounds. Detailed metrological quantification is proposed for the characterization of dual scale surface morphology. As etching proceeds, the mounds become higher, fewer and wider, and the underlying nano-roughness also increases. Increase in wafer temperature leads to smoother surfaces with lower, fewer and wider nano-mounds. A mechanism based on the deposition of etch inhibiting particles during the etching process is proposed for the explanation of the experimental behavior. In addition, appropriately designed experiments are conducted, and they confirm the presence of this mechanism.

Magnetic Nano-Materials: Truly Sustainable Green Chemistry Nano Catalysis

EPA Science Inventory

We envisioned a novel nano-catalyst system, which can bridge the homogenous and heterogeneous system, and simultaneously be cheaper, easily accessible (sustainable) and possibly does not require elaborate work-up. Because of its nano-size, i.e. high surface area, the contact betw...

Effect of Particle Size and Impact Velocity on Collision Behaviors Between Nano-Scale TiN Particles: MD Simulation.

PubMed

Yao, Hai-Long; Hu, Xiao-Zhen; Yang, Guan-Jun

2018-06-01

Inter-particle bonding formation which determines qualities of nano-scale ceramic coatings is influenced by particle collision behaviors during high velocity collision processes. In this study, collision behaviors between nano-scale TiN particles with different diameters were illuminated by using Molecular Dynamics simulation through controlling impact velocities. Results show that nano-scale TiN particles exhibit three states depending on particle sizes and impact velocities, i.e., bonding, bonding with localized fracturing, and rebounding. These TiN particles states are summarized into a parameter selection map providing an overview of the conditions in terms of particle sizes and velocities. Microstructure results show that localized atoms displacement and partial fracture around the impact region are main reasons for bonding formation of nano-scale ceramic particles, which shows differences from conventional particles refining and amorphization. A relationship between the adhesion energy and the rebound energy is established to understand bonding formation mechanism for nano-scale TiN particle collision. Results show that the energy relationship is depended on the particle sizes and impact velocities, and nano-scale ceramic particles can be bonded together as the adhesion energy being higher than the rebound energy.

Investigation on the special Smith-Purcell radiation from a nano-scale rectangular metallic grating

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Weiwei; Liu, Weihao, E-mail: liuwhao@ustc.edu.cn; Jia, Qika

The special Smith-Purcell radiation (S-SPR), which is from the radiating eigen modes of a grating, has remarkable higher intensity than the ordinary Smith-Purcell radiation. Yet in previous studies, the gratings were treated as perfect conductor without considering the surface plasmon polaritons (SPPs) which are of significance for the nano-scale gratings especially in the optical region. In present paper, the rigorous theoretical investigations on the S-SPR from a nano-grating with SPPs taken into consideration are carried out. The dispersion relations and radiation characteristics are obtained, and the results are verified by simulations. According to the analyses, the tunable light radiation canmore » be achieved by the S-SPR from a nano-grating, which offers a new prospect for developing the nano-scale light sources.« less

The Neurologic Assessment in Neuro-Oncology (NANO) Scale as an Assessment Tool for Survival in Patients With Primary Glioblastoma.

PubMed

Ung, Timothy H; Ney, Douglas E; Damek, Denise; Rusthoven, Chad G; Youssef, A Samy; Lillehei, Kevin O; Ormond, D Ryan

2018-03-30

The Neurologic Assessment in Neuro-Oncology (NANO) scale is a standardized objective metric designed to measure neurological function in neuro-oncology. Current neuroradiological evaluation guidelines fail to use specific clinical criteria for progression. To determine if the NANO scale was a reliable assessment tool in glioblastoma (GBM) patients and whether it correlated to survival. Our group performed a retrospective review of all patients with newly diagnosed GBM from January 1, 2010, through December 31, 2012, at our institution. We applied the NANO scale, Karnofsky performance score (KPS), Eastern Cooperative Oncology Group (ECOG) scale, Macdonald criteria, and the Response Assessment in Neuro-Oncology (RANO) criteria to patients at the time of diagnosis as well as at 3, 6, and 12 mo. Initial NANO score was correlated with overall survival at time of presentation. NANO progression was correlated with decreased survival in patients at 6 and 12 mo. A decrease in KPS was associated with survival at 3 and 6 mo, an increase in ECOG score was associated only at 3 mo, and radiological evaluation (RANO and Macdonald) was correlated at 3 and 6 mo. Only the NANO scale was associated with patient survival at 1 yr. NANO progression was the only metric that was linked to decreased overall survival when compared to RANO and Macdonald at 6 and 12 mo. The NANO scale is specific to neuro-oncology and can be used to assess patients with glioma. This retrospective analysis demonstrates the usefulness of the NANO scale in glioblastoma.

Scaling Effects on Materials Tribology: From Macro to Micro Scale.

PubMed

Stoyanov, Pantcho; Chromik, Richard R

2017-05-18

The tribological study of materials inherently involves the interaction of surface asperities at the micro to nanoscopic length scales. This is the case for large scale engineering applications with sliding contacts, where the real area of contact is made up of small contacting asperities that make up only a fraction of the apparent area of contact. This is why researchers have sought to create idealized experiments of single asperity contacts in the field of nanotribology. At the same time, small scale engineering structures known as micro- and nano-electromechanical systems (MEMS and NEMS) have been developed, where the apparent area of contact approaches the length scale of the asperities, meaning the real area of contact for these devices may be only a few asperities. This is essentially the field of microtribology, where the contact size and/or forces involved have pushed the nature of the interaction between two surfaces towards the regime where the scale of the interaction approaches that of the natural length scale of the features on the surface. This paper provides a review of microtribology with the purpose to understand how tribological processes are different at the smaller length scales compared to macrotribology. Studies of the interfacial phenomena at the macroscopic length scales (e.g., using in situ tribometry) will be discussed and correlated with new findings and methodologies at the micro-length scale.

Scaling Effects on Materials Tribology: From Macro to Micro Scale

PubMed Central

Stoyanov, Pantcho; Chromik, Richard R.

2017-01-01

The tribological study of materials inherently involves the interaction of surface asperities at the micro to nanoscopic length scales. This is the case for large scale engineering applications with sliding contacts, where the real area of contact is made up of small contacting asperities that make up only a fraction of the apparent area of contact. This is why researchers have sought to create idealized experiments of single asperity contacts in the field of nanotribology. At the same time, small scale engineering structures known as micro- and nano-electromechanical systems (MEMS and NEMS) have been developed, where the apparent area of contact approaches the length scale of the asperities, meaning the real area of contact for these devices may be only a few asperities. This is essentially the field of microtribology, where the contact size and/or forces involved have pushed the nature of the interaction between two surfaces towards the regime where the scale of the interaction approaches that of the natural length scale of the features on the surface. This paper provides a review of microtribology with the purpose to understand how tribological processes are different at the smaller length scales compared to macrotribology. Studies of the interfacial phenomena at the macroscopic length scales (e.g., using in situ tribometry) will be discussed and correlated with new findings and methodologies at the micro-length scale. PMID:28772909

Nano-Scale Spatial Assessment of Calcium Distribution in Coccolithophores Using Synchrotron-Based Nano-CT and STXM-NEXAFS

PubMed Central

Sun, Shiyong; Yao, Yanchen; Zou, Xiang; Fan, Shenglan; Zhou, Qing; Dai, Qunwei; Dong, Faqin; Liu, Mingxue; Nie, Xiaoqin; Tan, Daoyong; Li, Shuai

2014-01-01

Calcified coccolithophores generate calcium carbonate scales around their cell surface. In light of predicted climate change and the global carbon cycle, the biomineralization ability of coccoliths has received growing interest. However, the underlying biomineralization mechanism is not yet well understood; the lack of non-invasive characterizing tools to obtain molecular level information involving biogenic processes and biomineral components remain significant challenges. In the present study, synchrotron-based Nano-computed Tomography (Nano-CT) and Scanning Transmission X-ray Microscopy-Near-edge X-ray Absorption Fine Structure Spectromicroscopy (STXM-NEXAFS) techniques were employed to identify Ca spatial distribution and investigate the compositional chemistry and distinctive features of the association between biomacromolecules and mineral components of calcite present in coccoliths. The Nano-CT results show that the coccolith scale vesicle is similar as a continuous single channel. The mature coccoliths were intracellularly distributed and immediately ejected and located at the exterior surface to form a coccoshpere. The NEXAFS spectromicroscopy results of the Ca L edge clearly demonstrate the existence of two levels of gradients spatially, indicating two distinctive forms of Ca in coccoliths: a crystalline-poor layer surrounded by a relatively crystalline-rich layer. The results show that Sr is absorbed by the coccoliths and that Sr/Ca substitution is rather homogeneous within the coccoliths. Our findings indicate that synchrotron-based STXM-NEXAFS and Nano-CT are excellent tools for the study of biominerals and provide information to clarify biomineralization mechanism. PMID:25530614

Wavelength-scale photonic-crystal laser formed by electron-beam-induced nano-block deposition.

PubMed

Seo, Min-Kyo; Kang, Ju-Hyung; Kim, Myung-Ki; Ahn, Byeong-Hyeon; Kim, Ju-Young; Jeong, Kwang-Yong; Park, Hong-Gyu; Lee, Yong-Hee

2009-04-13

A wavelength-scale cavity is generated by printing a carbonaceous nano-block on a photonic-crystal waveguide. The nanometer-size carbonaceous block is grown at a pre-determined region by the electron-beam-induced deposition method. The wavelength-scale photonic-crystal cavity operates as a single mode laser, near 1550 nm with threshold of approximately 100 microW at room temperature. Finite-difference time-domain computations show that a high-quality-factor cavity mode is defined around the nano-block with resonant wavelength slightly longer than the dispersion-edge of the photonic-crystal waveguide. Measured near-field images exhibit photon distribution well-localized in the proximity of the printed nano-block. Linearly-polarized emission along the vertical direction is also observed.

Fabrication of nano-scale Cu bond pads with seal design in 3D integration applications.

PubMed

Chen, K N; Tsang, C K; Wu, W W; Lee, S H; Lu, J Q

2011-04-01

A method to fabricate nano-scale Cu bond pads for improving bonding quality in 3D integration applications is reported. The effect of Cu bonding quality on inter-level via structural reliability for 3D integration applications is investigated. We developed a Cu nano-scale-height bond pad structure and fabrication process for improved bonding quality by recessing oxides using a combination of SiO2 CMP process and dilute HF wet etching. In addition, in order to achieve improved wafer-level bonding, we introduced a seal design concept that prevents corrosion and provides extra mechanical support. Demonstrations of these concepts and processes provide the feasibility of reliable nano-scale 3D integration applications.

Performance evaluation of bimodal thermite composites : nano- vs miron-scale particles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moore, K. M.; Pantoya, M.; Son, S. F.

2004-01-01

In recent years many studies of metastable interstitial composites (MIC) have shown vast combustion improvements over traditional thermite materials. The main difference between these two materials is the size of the fuel particles in the mixture. Decreasing the fuel size from the micron to nanometer range significantly increases the combustion wave speed and ignition sensitivity. Little is known, however, about the critical level of nano-sized fuel particles needed to enhance the performance of the traditional thermite. Ignition sensitivity experiments were performed using Al/MoO{sub 3} pellets at a theoretical maximum density of 50% (2 g/cm{sup 3}). The Al fuel particles weremore » prepared as bi-modal size distributions with micron (i.e., 4 and 20 {micro}m diameter) and nano-scale Al particles. The micron-scale Al was replaced in 10% increments by 80 nm Al particles until the fuel was 100% 80 nm Al. These bi-modal distributions allow the unique characteristics of nano-scale materials to be better understood. The pellets were ignited using a 50-W CO{sub 2} laser. High speed imaging diagnostics were used to measure ignition delay times, and micro-thermocouples were used to measure ignition temperatures. Combustion wave speeds were also examined.« less

Contact area of rough spheres: Large scale simulations and simple scaling laws

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pastewka, Lars, E-mail: lars.pastewka@kit.edu; Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218; Robbins, Mark O., E-mail: mr@pha.jhu.edu

2016-05-30

We use molecular simulations to study the nonadhesive and adhesive atomic-scale contact of rough spheres with radii ranging from nanometers to micrometers over more than ten orders of magnitude in applied normal load. At the lowest loads, the interfacial mechanics is governed by the contact mechanics of the first asperity that touches. The dependence of contact area on normal force becomes linear at intermediate loads and crosses over to Hertzian at the largest loads. By combining theories for the limiting cases of nominally flat rough surfaces and smooth spheres, we provide parameter-free analytical expressions for contact area over the wholemore » range of loads. Our results establish a range of validity for common approximations that neglect curvature or roughness in modeling objects on scales from atomic force microscope tips to ball bearings.« less

Nano/micro-scale magnetophoretic devices for biomedical applications

NASA Astrophysics Data System (ADS)

Lim, Byeonghwa; Vavassori, Paolo; Sooryakumar, R.; Kim, CheolGi

2017-01-01

In recent years there have been tremendous advances in the versatility of magnetic shuttle technology using nano/micro-scale magnets for digital magnetophoresis. While the technology has been used for a wide variety of single-cell manipulation tasks such as selection, capture, transport, encapsulation, transfection, or lysing of magnetically labeled and unlabeled cells, it has also expanded to include parallel actuation and study of multiple bio-entities. The use of nano/micro-patterned magnetic structures that enable remote control of the applied forces has greatly facilitated integration of the technology with microfluidics, thereby fostering applications in the biomedical arena. The basic design and fabrication of various scaled magnets for remote manipulation of individual and multiple beads/cells, and their associated energies and forces that underlie the broad functionalities of this approach, are presented. One of the most useful features enabled by such advanced integrated engineering is the capacity to remotely tune the magnetic field gradient and energy landscape, permitting such multipurpose shuttles to be implemented within lab-on-chip platforms for a wide range of applications at the intersection of cellular biology and biotechnology.

Tribological behavior of micro/nano-patterned surfaces in contact with AFM colloidal probe

NASA Astrophysics Data System (ADS)

Zhang, Xiaoliang; Wang, Xiu; Kong, Wen; Yi, Gewen; Jia, Junhong

2011-10-01

In effort to investigate the influence of the micro/nano-patterning or surface texturing on the nanotribological properties of patterned surfaces, the patterned polydimethylsiloxane (PDMS) surfaces with pillars were fabricated by replica molding technique. The surface morphologies of patterned PDMS surfaces with varying pillar sizes and spacing between pillars were characterized by atomic force microscope (AFM) and scanning electron microscope (SEM). The AFM/FFM was used to acquire the friction force images of micro/nano-patterned surfaces using a colloidal probe. A difference in friction force produced a contrast on the friction force images when the colloidal probe slid over different regions of the patterned polymer surfaces. The average friction force of patterned surface was related to the spacing between the pillars and their size. It decreased with the decreasing of spacing between the pillars and the increasing of pillar size. A reduction in friction force was attributed to the reduced area of contact between patterned surface and colloidal probe. Additionally, the average friction force increased with increasing applied load and sliding velocity.

Time domain contact model for tyre/road interaction including nonlinear contact stiffness due to small-scale roughness

NASA Astrophysics Data System (ADS)

Andersson, P. B. U.; Kropp, W.

2008-11-01

Rolling resistance, traction, wear, excitation of vibrations, and noise generation are all attributes to consider in optimisation of the interaction between automotive tyres and wearing courses of roads. The key to understand and describe the interaction is to include a wide range of length scales in the description of the contact geometry. This means including scales on the order of micrometres that have been neglected in previous tyre/road interaction models. A time domain contact model for the tyre/road interaction that includes interfacial details is presented. The contact geometry is discretised into multiple elements forming pairs of matching points. The dynamic response of the tyre is calculated by convolving the contact forces with pre-calculated Green's functions. The smaller-length scales are included by using constitutive interfacial relations, i.e. by using nonlinear contact springs, for each pair of contact elements. The method is presented for normal (out-of-plane) contact and a method for assessing the stiffness of the nonlinear springs based on detailed geometry and elastic data of the tread is suggested. The governing equations of the nonlinear contact problem are solved with the Newton-Raphson iterative scheme. Relations between force, indentation, and contact stiffness are calculated for a single tread block in contact with a road surface. The calculated results have the same character as results from measurements found in literature. Comparison to traditional contact formulations shows that the effect of the small-scale roughness is large; the contact stiffness is only up to half of the stiffness that would result if contact is made over the whole element directly to the bulk of the tread. It is concluded that the suggested contact formulation is a suitable model to include more details of the contact interface. Further, the presented result for the tread block in contact with the road is a suitable input for a global tyre/road interaction model

Density functional theory studies on the nano-scaled composites consisted of graphene and acyl hydrazone molecules

NASA Astrophysics Data System (ADS)

Ren, J. L.; Zhou, L.; Lv, Z. C.; Ding, C. H.; Wu, Y. H.; Bai, H. C.

2016-07-01

Graphene, which is the first obtained single atomic layer 2D materials, has drawn a great of concern in nano biotechnology due to the unique property. On one hand, acyl hydrazone compounds belonging to the Schif bases have aroused considerable attention in medicine, pharmacy, and analytical reagent. However, few understanding about the interaction between graphene and acyl hydrazone molecules is now available. And such investigations are much crucial for the applications of these new nano-scaled composites. The current work revealed theoretical investigations on the nano-scaled composites built by acyl hydrazone molecules loaded on the surface of graphene. The relative energy, electronic property and the interaction between the counterparts of graphene/acyl hydrazone composites are investigated based on the density functional theory calculations. According to the obtained adsorption energy, the formation of the nano-scaled composite from the isolated graphene and acyl hydrazone molecule is exothermic, and thus it is energetically favorable to form these nano composites in viewpoint of total energy change. The frontier molecular orbital for the nano composite is mainly distributed at the graphene part, leading to that the energy levels of the frontier molecular orbital of the nano composites are very close to that of isolated graphene. Moreover, the counterpart interaction for the graphene/acyl hydrazone composites is also explored based on the discussions of orbital hybridization, charge redistribution and Van der Waals interaction.

From the Nano- to the Macroscale - Bridging Scales for the Moving Contact Line Problem

NASA Astrophysics Data System (ADS)

Nold, Andreas; Sibley, David; Goddard, Benjamin; Kalliadasis, Serafim; Complex Multiscale Systems Team

2016-11-01

The moving contact line problem remains an unsolved fundamental problem in fluid mechanics. At the heart of the problem is its multiscale nature: a nanoscale region close to the solid boundary where the continuum hypothesis breaks down, must be resolved before effective macroscale parameters such as contact line friction and slip can be obtained. To capture nanoscale properties very close to the contact line and to establish a link to the macroscale behaviour, we employ classical density-functional theory (DFT), in combination with extended Navier-Stokes-like equations. Using simple models for viscosity and slip at the wall, we compare our computations with the Molecular Kinetic Theory, by extracting the contact line friction, depending on the imposed temperature of the fluid. A key fluid property captured by DFT is the fluid layering at the wall-fluid interface, which has a large effect on the shearing properties of a fluid. To capture this crucial property, we propose an anisotropic model for the viscosity, which also allows us to scrutinize the effect of fluid layering on contact line friction.

Sustainable nano-catalysis

EPA Science Inventory

A novel nano-catalyst system which bridges the homogenous and heterogeneous system is described that is cheaper, easily accessible (sustainable) and requires no need of catalyst filtration during the work-up. Because of its nano-size, i.e. high surface area, the contact between r...

Non-contact tensile viscoelastic characterization of microscale biological materials

NASA Astrophysics Data System (ADS)

Li, Yuhui; Hong, Yuan; Xu, Guang-Kui; Liu, Shaobao; Shi, Qiang; Tang, Deding; Yang, Hui; Genin, Guy M.; Lu, Tian Jian; Xu, Feng

2018-06-01

Many structures and materials in nature and physiology have important "meso-scale" structures at the micron length-scale whose tensile responses have proven difficult to characterize mechanically. Although techniques such as atomic force microscopy and micro- and nano-identation are mature for compression and indentation testing at the nano-scale, and standard uniaxial and shear rheometry techniques exist for the macroscale, few techniques are applicable for tensile-testing at the micrometre-scale, leaving a gap in our understanding of hierarchical biomaterials. Here, we present a novel magnetic mechanical testing (MMT) system that enables viscoelastic tensile testing at this critical length scale. The MMT system applies non-contact loading, avoiding gripping and surface interaction effects. We demonstrate application of the MMT system to the first analyses of the pure tensile responses of several native and engineered tissue systems at the mesoscale, showing the broad potential of the system for exploring micro- and meso-scale analysis of structured and hierarchical biological systems.

Non-contact tensile viscoelastic characterization of microscale biological materials

NASA Astrophysics Data System (ADS)

Li, Yuhui; Hong, Yuan; Xu, Guang-Kui; Liu, Shaobao; Shi, Qiang; Tang, Deding; Yang, Hui; Genin, Guy M.; Lu, Tian Jian; Xu, Feng

2018-01-01

Many structures and materials in nature and physiology have important "meso-scale" structures at the micron length-scale whose tensile responses have proven difficult to characterize mechanically. Although techniques such as atomic force microscopy and micro- and nano-identation are mature for compression and indentation testing at the nano-scale, and standard uniaxial and shear rheometry techniques exist for the macroscale, few techniques are applicable for tensile-testing at the micrometre-scale, leaving a gap in our understanding of hierarchical biomaterials. Here, we present a novel magnetic mechanical testing (MMT) system that enables viscoelastic tensile testing at this critical length scale. The MMT system applies non-contact loading, avoiding gripping and surface interaction effects. We demonstrate application of the MMT system to the first analyses of the pure tensile responses of several native and engineered tissue systems at the mesoscale, showing the broad potential of the system for exploring micro- and meso-scale analysis of structured and hierarchical biological systems.

Crystallization of high-strength nano-scale leucite glass-ceramics.

PubMed

Theocharopoulos, A; Chen, X; Wilson, R M; Hill, R; Cattell, M J

2013-11-01

Fine-grained, high strength, translucent leucite dental glass-ceramics are synthesized via controlled crystallization of finely milled glass powders. The objectives of this study were to utilize high speed planetary milling of an aluminosilicate glass for controlled surface crystallization of nano-scale leucite glass-ceramics and to test the biaxial flexural strength. An aluminosilicate glass was synthesized, attritor or planetary milled and heat-treated. Glasses and glass-ceramics were characterized using particle size analysis, X-ray diffraction and scanning electron microscopy. Experimental (fine and nanoscale) and commercial (Ceramco-3, IPS Empress Esthetic) leucite glass-ceramics were tested using the biaxial flexural strength (BFS) test. Gaussian and Weibull statistics were applied. Experimental planetary milled glass-ceramics showed an increased leucite crystal number and nano-scale median crystal sizes (0.048-0.055 μm(2)) as a result of glass particle size reduction and heat treatments. Experimental materials had significantly (p<0.05) higher mean BFS and characteristic strength values than the commercial materials. Attritor milled and planetary milled (2h) materials showed no significant (p>0.05) strength difference. All other groups' mean BFS and characteristic strengths were found to be significantly different (p<0.05) to each other. The mean (SD) MPa strengths measured were: Attritor milled: 252.4 (38.7), Planetary milled: 225.4 (41.8) [4h milling] 255.0 (35.0) [2h milling], Ceramco-3: 75.7 (6.8) and IPS Empress: 165.5 (30.6). Planetary milling enabled synthesis of nano-scale leucite glass-ceramics with high flexural strength. These materials may help to reduce problems associated with brittle fracture of all-ceramic restorations and give reduced enamel wear. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Exploring Chondrule and CAI Rims Using Micro- and Nano-Scale Petrological and Compositional Analysis

NASA Astrophysics Data System (ADS)

Cartwright, J. A.; Perez-Huerta, A.; Leitner, J.; Vollmer, C.

2017-12-01

As the major components within chondrites, chondrules (mm-sized droplets of quenched silicate melt) and calcium-aluminum-rich inclusions (CAI, refractory) represent the most abundant and the earliest materials that solidified from the solar nebula. However, the exact formation mechanisms of these clasts, and whether these processes are related, remains unconstrained, despite extensive petrological and compositional study. By taking advantage of recent advances in nano-scale tomographical techniques, we have undertaken a combined micro- and nano-scale study of CAI and chondrule rim morphologies, to investigate their formation mechanisms. The target lithologies for this research are Wark-Lovering rims (WLR), and fine-grained rims (FGR) around CAIs and chondrules respectively, present within many chondrites. The FGRs, which are up to 100 µm thick, are of particular interest as recent studies have identified presolar grains within them. These grains predate the formation of our Solar System, suggesting FGR formation under nebular conditions. By contrast, WLRs are 10-20 µm thick, made of different compositional layers, and likely formed by flash-heating shortly after CAI formation, thus recording nebular conditions. A detailed multi-scale study of these respective rims will enable us to better understand their formation histories and determine the potential for commonality between these two phases, despite reports of an observed formation age difference of up to 2-3 Myr. We are using a combination of complimentary techniques on our selected target areas: 1) Micro-scale characterization using standard microscopic and compositional techniques (SEM-EBSD, EMPA); 2) Nano-scale characterization of structures using transmission electron microscopy (TEM) and elemental, isotopic and tomographic analysis with NanoSIMS and atom probe tomography (APT). Preliminary nano-scale APT analysis of FGR morphologies within the Allende carbonaceous chondrite has successfully discerned

Live-cell imaging of ER-PM contact architecture by a novel TIRFM approach reveals extension of junctions in response to store-operated Ca2+-entry.

PubMed

Poteser, Michael; Leitinger, Gerd; Pritz, Elisabeth; Platzer, Dieter; Frischauf, Irene; Romanin, Christoph; Groschner, Klaus

2016-10-19

Nanometer-spaced appositions between endoplasmic reticulum and plasma membrane (ER-PM junctions) stabilized by membrane-joining protein complexes are critically involved in cellular Ca 2+ -handling and lipid trafficking. ER-PM junctional architecture and plasticity associated with inter-membrane communication are as yet barely understood. Here, we introduce a method to precisely characterize ER-PM junction morphology and dynamics with high temporal resolution and minimal disturbance of junctional intermembrane communication. We show that expression of soluble cytosolic fluorophores in combination with TIRFM enables to delineate ER and PM distance in the range of 10-150 nm. Live-cell imaging of sub-plasmalemmal structures in RBL-2H3 mast cells by this method, designated as fluorescence density mapping (FDM), revealed profound dynamics of ER-PM contact sites in response to store-depletion. We report the existence of a Ca 2+ -dependent process that expands the junctional ER to enlarge its contact surface with the PM, thereby promoting and stabilizing STIM1-Orai1 competent ER-PM junctions.

Modeling Near-Crack-Tip Plasticity from Nano- to Micro-Scales

NASA Technical Reports Server (NTRS)

Glaessgen, Edward H.; Saether, Erik; Hochhalter, Jake D.; Yamakov, Vesselin I.

2010-01-01

Several efforts that are aimed at understanding the plastic deformation mechanisms related to crack propagation at the nano-, meso- and micro-length scales including atomistic simulation, discrete dislocation plasticity, strain gradient plasticity and crystal plasticity are discussed. The paper focuses on discussion of newly developed methodologies and their application to understanding damage processes in aluminum and its alloys. Examination of plastic mechanisms as a function of increasing length scale illustrates increasingly complex phenomena governing plasticity

Controlling high-throughput manufacturing at the nano-scale

NASA Astrophysics Data System (ADS)

Cooper, Khershed P.

2013-09-01

Interest in nano-scale manufacturing research and development is growing. The reason is to accelerate the translation of discoveries and inventions of nanoscience and nanotechnology into products that would benefit industry, economy and society. Ongoing research in nanomanufacturing is focused primarily on developing novel nanofabrication techniques for a variety of applications—materials, energy, electronics, photonics, biomedical, etc. Our goal is to foster the development of high-throughput methods of fabricating nano-enabled products. Large-area parallel processing and highspeed continuous processing are high-throughput means for mass production. An example of large-area processing is step-and-repeat nanoimprinting, by which nanostructures are reproduced again and again over a large area, such as a 12 in wafer. Roll-to-roll processing is an example of continuous processing, by which it is possible to print and imprint multi-level nanostructures and nanodevices on a moving flexible substrate. The big pay-off is high-volume production and low unit cost. However, the anticipated cost benefits can only be realized if the increased production rate is accompanied by high yields of high quality products. To ensure product quality, we need to design and construct manufacturing systems such that the processes can be closely monitored and controlled. One approach is to bring cyber-physical systems (CPS) concepts to nanomanufacturing. CPS involves the control of a physical system such as manufacturing through modeling, computation, communication and control. Such a closely coupled system will involve in-situ metrology and closed-loop control of the physical processes guided by physics-based models and driven by appropriate instrumentation, sensing and actuation. This paper will discuss these ideas in the context of controlling high-throughput manufacturing at the nano-scale.

Fabrication of a 3D micro/nano dual-scale carbon array and its demonstration as the microelectrodes for supercapacitors

NASA Astrophysics Data System (ADS)

Jiang, Shulan; Shi, Tielin; Gao, Yang; Long, Hu; Xi, Shuang; Tang, Zirong

2014-04-01

An easily accessible method is proposed for the fabrication of a 3D micro/nano dual-scale carbon array with a large surface area. The process mainly consists of three critical steps. Firstly, a hemispherical photoresist micro-array was obtained by the cost-effective nanoimprint lithography process. Then the micro-array was transformed into hierarchical structures with longitudinal nanowires on the microstructure surface by oxygen plasma etching. Finally, the micro/nano dual-scale carbon array was fabricated by carbonizing these hierarchical photoresist structures. It has also been demonstrated that the micro/nano dual-scale carbon array can be used as the microelectrodes for supercapacitors by the electrodeposition of a manganese dioxide (MnO2) film onto the hierarchical carbon structures with greatly enhanced electrochemical performance. The specific gravimetric capacitance of the deposited micro/nano dual-scale microelectrodes is estimated to be 337 F g-1 at the scan rate of 5 mV s-1. This proposed approach of fabricating a micro/nano dual-scale carbon array provides a facile way in large-scale microstructures’ manufacturing for a wide variety of applications, including sensors and on-chip energy storage devices.

Plasmofluidics: Merging Light and Fluids at the Micro-/Nano-Scale

PubMed Central

Wang, Mingsong; Zhao, Chenglong; Miao, Xiaoyu; Zhao, Yanhui; Rufo, Joseph

2016-01-01

Plasmofluidics is the synergistic integration of plasmonics and micro/nano fluidics in devices and applications in order to enhance performance. There has been significant progress in the emerging field of plasmofluidics in recent years. By utilizing the capability of plasmonics to manipulate light at the nanoscale, combined with the unique optical properties of fluids, and precise manipulation via micro/nano fluidics, plasmofluidic technologies enable innovations in lab-on-a-chip systems, reconfigurable photonic devices, optical sensing, imaging, and spectroscopy. In this review article, we examine and categorize the most recent advances in plasmofluidics into plasmon-enhanced functionalities in microfluidics and microfluidics-enhanced plasmonic devices. The former focuses on plasmonic manipulations of fluids, bubbles, particles, biological cells, and molecules at the micro-/nano-scale. The latter includes technological advances that apply microfluidic principles to enable reconfigurable plasmonic devices and performance-enhanced plasmonic sensors. We conclude with our perspectives on the upcoming challenges, opportunities, and the possible future directions of the emerging field of plasmofluidics. PMID:26140612

C1orf163/RESA1 is a novel mitochondrial intermembrane space protein connected to respiratory chain assembly.

PubMed

Kozjak-Pavlovic, Vera; Prell, Florian; Thiede, Bernd; Götz, Monika; Wosiek, Dominik; Ott, Christine; Rudel, Thomas

2014-02-20

Oxidative phosphorylation (OXPHOS) in mitochondria takes place at the inner membrane, which folds into numerous cristae. The stability of cristae depends, among other things, on the mitochondrial intermembrane space bridging complex. Its components include inner mitochondrial membrane protein mitofilin and outer membrane protein Sam50. We identified a conserved, uncharacterized protein, C1orf163 [SEL1 repeat containing 1 protein (SELRC1)], as one of the proteins significantly reduced after the knockdown of Sam50 and mitofilin. We show that C1orf163 is a mitochondrial soluble intermembrane space protein. Sam50 depletion affects moderately the import and assembly of C1orf163 into two protein complexes of approximately 60kDa and 150kDa. We observe that the knockdown of C1orf163 leads to reduction of levels of proteins belonging to the OXPHOS complexes. The activity of complexes I and IV is reduced in C1orf163-depleted cells, and we observe the strongest defects in the assembly of complex IV. Therefore, we propose C1orf163 to be a novel factor important for the assembly of respiratory chain complexes in human mitochondria and suggest to name it RESA1 (for RESpiratory chain Assembly 1). Copyright © 2013 Elsevier Ltd. All rights reserved.

Surface roughness: A review of its measurement at micro-/nano-scale

NASA Astrophysics Data System (ADS)

Gong, Yuxuan; Xu, Jian; Buchanan, Relva C.

2018-01-01

The measurement of surface roughness at micro-/nano-scale is of great importance to metrological, manufacturing, engineering, and scientific applications given the critical roles of roughness in physical and chemical phenomena. The surface roughness of materials can significantly change the way of how they interact with light, phonons, molecules, and so forth, thus surface roughness ultimately determines the functionality and property of materials. In this short review, the techniques of measuring micro-/nano-scale surface roughness are discussed with special focus on the limitations and capabilities of each technique. In addition, the calculations of surface roughness and their theoretical background are discussed to offer readers a better understanding of the importance of post-measurement analysis. Recent progress on fractal analysis of surface roughness is discussed to shed light on the future efforts in surface roughness measurement.

New approach for pattern collapse problem by increasing contact area at sub-100nm patterning

NASA Astrophysics Data System (ADS)

Lee, Sung-Koo; Jung, Jae Chang; Lee, Min Suk; Lee, Sung K.; Kim, Sam Young; Hwang, Young-Sun; Bok, Cheol K.; Moon, Seung-Chan; Shin, Ki S.; Kim, Sang-Jung

2003-06-01

To accomplish minimizing feature size to sub 100nm, new light sources for photolithography are emerging, such as ArF(193nm), F2(157nm), and EUV(13nm). However as the pattern size decreases to sub 100nm, a new obstacle, that is pattern collapse problem, becomes most serious bottleneck to the road for the sub 100 nm lithography. The main reason for this pattern collapse problem is capillary force that is increased as the pattern size decreases. As a result there were some trials to decrease this capillary force by changing developer or rinse materials that had low surface tension. On the other hands, there were other efforts to increase adhesion between resists and sub materials (organic BARC). In this study, we will propose a novel approach to solve pattern collapse problems by increasing contact area between sub material (organic BARC) and resist pattern. The basic concept of this approach is that if nano-scale topology is made at the sub material, the contact area between sub materials and resist will be increased. The process scheme was like this. First after coating and baking of organic BARC material, the nano-scale topology (3~10nm) was made by etching at this organic BARC material. On this nano-scale topology, resist was coated and exposed. Finally after develop, the contact area between organic BARC and resist could be increased. Though nano-scale topology was made by etching technology, this 20nm topology variation induced large substrate reflectivity of 4.2% and as a result the pattern fidelity was not so good at 100nm 1:1 island pattern. So we needed a new method to improve pattern fidelity problem. This pattern fidelity problem could be solved by introducing a sacrificial BARC layer. The process scheme was like this. First organic BARC was coated of which k value was about 0.64 and then sacrificial BARC layers was coated of which k value was about 0.18 on the organic BARC. The nano-scale topology (1~4nm) was made by etching of this sacrificial BARC layer

A discrete pathway for the transfer of intermembrane space proteins across the outer membrane of mitochondria.

PubMed

Gornicka, Agnieszka; Bragoszewski, Piotr; Chroscicki, Piotr; Wenz, Lena-Sophie; Schulz, Christian; Rehling, Peter; Chacinska, Agnieszka

2014-12-15

Mitochondrial proteins are synthesized on cytosolic ribosomes and imported into mitochondria with the help of protein translocases. For the majority of precursor proteins, the role of the translocase of the outer membrane (TOM) and mechanisms of their transport across the outer mitochondrial membrane are well recognized. However, little is known about the mode of membrane translocation for proteins that are targeted to the intermembrane space via the redox-driven mitochondrial intermembrane space import and assembly (MIA) pathway. On the basis of the results obtained from an in organello competition import assay, we hypothesized that MIA-dependent precursor proteins use an alternative pathway to cross the outer mitochondrial membrane. Here we demonstrate that this alternative pathway involves the protein channel formed by Tom40. We sought a translocation intermediate by expressing tagged versions of MIA-dependent proteins in vivo. We identified a transient interaction between our model substrates and Tom40. Of interest, outer membrane translocation did not directly involve other core components of the TOM complex, including Tom22. Thus MIA-dependent proteins take another route across the outer mitochondrial membrane that involves Tom40 in a form that is different from the canonical TOM complex. © 2014 Gornicka et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

Phototoxicity and Dosimetry of Nano-scaleTitanium Dioxide in Aquatic Organisms

EPA Science Inventory

We have been testing nanoscale TiO2 (primarily Evonik P25) in acute exposures to identify and quantify its phototoxicity under solar simulated radiation (SSR), and to develop dose metrics reflective of both nano-scale properties and the photon component of its potency. Several e...

Phototoxicity and Dosimetry of Nano-scale Titanium Dioxide in Aquatic Organisms

EPA Science Inventory

We have been testing nanoscale TiO2 (primarily Evonik P25) in acute exposures to identify and quantify its phototoxicity under solar simulated radiation (SSR), and to develop dose metrics reflective of both nano-scale properties and the photon component of its potency. Several e...

Replication of surface nano-structure of the wing of dragonfly ( Pantala Flavescens) using nano-molding and UV nanoimprint lithography

NASA Astrophysics Data System (ADS)

Cho, Joong-Yeon; Kim, Gyutae; Kim, Sungwook; Lee, Heon

2013-07-01

The hydrophobicity of a dragonfly's wing originates from the naturally occurring nano-structure on its surface. The nano-structure on a dragonfly's wing consists of an array of nano-sized pillars, 100 nm in diameter. We re-create this hydrophobicity on various substrates, such as Si, glass, curved acrylic polymer, and flexible PET film, by replicating the nano-structure using UV curable nano-imprint lithography (NIL) and PDMS molding. The success of the nano-structure duplication was confirmed using scanning electron microscopy (SEM). The hydrophobicity was measured by water-based contact angle measurements. The water contact angle of the replica made of UV cured polymer was 135° ± 2°, which was slightly lower than that of the original dragonfly's wing (145° ± 2°), but much higher than that of the UV cured polymer surface without any nano-sized pillars (80°). The hydrophobicity was further improved by applying a coating of Teflon-like material.

From micro to nano contacts in biological attachment devices

PubMed Central

Arzt, Eduard; Gorb, Stanislav; Spolenak, Ralph

2003-01-01

Animals with widely varying body weight, such as flies, spiders, and geckos, can adhere to and move along vertical walls and even ceilings. This ability is caused by very efficient attachment mechanisms in which patterned surface structures interact with the profile of the substrate. An extensive microscopic study has shown a strong inverse scaling effect in these attachment devices. Whereas μm dimensions of the terminal elements of the setae are sufficient for flies and beetles, geckos must resort to sub-μm devices to ensure adhesion. This general trend is quantitatively explained by applying the principles of contact mechanics, according to which splitting up the contact into finer subcontacts increases adhesion. This principle is widely spread in design of natural adhesive systems and may also be transferred into practical applications. PMID:12960386

Multi-scale Observation of Biological Interactions of Nanocarriers: from Nano to Macro

PubMed Central

Jin, Su-Eon; Bae, Jin Woo; Hong, Seungpyo

2010-01-01

Microscopic observations have played a key role in recent advancements in nanotechnology-based biomedical sciences. In particular, multi-scale observation is necessary to fully understand the nano-bio interfaces where a large amount of unprecedented phenomena have been reported. This review describes how to address the physicochemical and biological interactions of nanocarriers within the biological environments using microscopic tools. The imaging techniques are categorized based on the size scale of detection. For observation of the nano-scale biological interactions of nanocarriers, we discuss atomic force microscopy (AFM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). For the micro to macro-scale (in vitro and in vivo) observation, we focus on confocal laser scanning microscopy (CLSM) as well as in vivo imaging systems such as magnetic resonance imaging (MRI), superconducting quantum interference devices (SQUIDs), and IVIS®. Additionally, recently developed combined techniques such as AFM-CLSM, correlative Light and Electron Microscopy (CLEM), and SEM-spectroscopy are also discussed. In this review, we describe how each technique helps elucidate certain physicochemical and biological activities of nanocarriers such as dendrimers, polymers, liposomes, and polymeric/inorganic nanoparticles, thus providing a toolbox for bioengineers, pharmaceutical scientists, biologists, and research clinicians. PMID:20232368

Application of exergetic sustainability index to a nano-scale irreversible Brayton cycle operating with ideal Bose and Fermi gasses

NASA Astrophysics Data System (ADS)

Açıkkalp, Emin; Caner, Necmettin

2015-09-01

In this study, a nano-scale irreversible Brayton cycle operating with quantum gasses including Bose and Fermi gasses is researched. Developments in the nano-technology cause searching the nano-scale machines including thermal systems to be unavoidable. Thermodynamic analysis of a nano-scale irreversible Brayton cycle operating with Bose and Fermi gasses was performed (especially using exergetic sustainability index). In addition, thermodynamic analysis involving classical evaluation parameters such as work output, exergy output, entropy generation, energy and exergy efficiencies were conducted. Results are submitted numerically and finally some useful recommendations were conducted. Some important results are: entropy generation and exergetic sustainability index are affected mostly for Bose gas and power output and exergy output are affected mostly for the Fermi gas by x. At the high temperature conditions, work output and entropy generation have high values comparing with other degeneracy conditions.

Nano-scale gene delivery systems; current technology, obstacles, and future directions.

PubMed

Garcia-Guerra, Antonio; Dunwell, Thomas L; Trigueros, Sonia

2018-01-07

Within the different applications of nanomedicine currently being developed, nano-gene delivery is appearing as an exciting new technique with the possibility to overcome recognised hurdles and fulfill several biological and medical needs. The central component of all delivery systems is the requirement for the delivery of genetic material into cells, and for them to eventually reside in the nucleus where their desired function will be exposed. However, genetic material does not passively enter cells; thus, a delivery system is necessary. The emerging field of nano-gene delivery exploits the use of new materials and the properties that arise at the nanometre-scale to produce delivery vectors that can effectively deliver genetic material into a variety of different types of cells. The novel physicochemical properties of the new delivery vectors can be used to address the current challenges existing in nucleic acid delivery in vitro and in vivo. While there is a growing interest in nanostructure-based gene delivery, the field is still in its infancy, and there is yet much to discover about nanostructures and their physicochemical properties in a biological context. We carry out an organized and focused search of bibliographic databases. Our results suggest that despite new breakthroughs in nanostructure synthesis and advanced characterization techniques, we still face many barriers in producing highly efficient and non-toxic delivery systems. In this review, we overview the types of systems currently used for clinical and biomedical research applications along with their advantages and disadvantages, as well as discussing barriers that arise from nano-scale interactions with biological material. In conclusion, we hope that by bringing the far reaching multidisciplinary nature of nano-gene delivery to light, new targeted nanotechnology-bases strategies are developed to overcome the major challenges covered in this review. Copyright© Bentham Science Publishers; For

Enrichment of Glycoproteins using Nano-scale Chelating Con A Monolithic Capillary Chromatography

PubMed Central

Feng, Shun; Yang, Na; Pennathur, Subramaniam; Goodison, Steve; Lubman, David M.

2009-01-01

Immobilized lectin chromatography can be employed for glycoprotein enrichment, but commonly used columns have limitations of yield and resolution. In order to improve efficiency and to make the technique applicable to minimal sample material, we have developed a nano-scale chelating Concanavalin A (Con A) monolithic capillary prepared using GMA-EDMA (glycidyl methacrylate–co-ethylene dimethacrylate) as polymeric support. Con A was immobilized on Cu(II)-charged iminodiacetic acid (IDA) regenerable sorbents by forming a IDA:Cu(II):Con A sandwich affinity structure that has high column capacity as well as stability. When compared with conventional Con A lectin chromatography, the monolithic capillary enabled the better reproducible detection of over double the number of unique N-glycoproteins in human urine samples. Utility for analysis of minimal biological samples was confirmed by the successful elucidation of glycoprotein profiles in mouse urine samples at the microliter scale. The improved efficiency of the nano-scale monolithic capillary will impact the analysis of glycoproteins in complex biological samples, especially where only limited material may be available. PMID:19366252

The dependence of nano-contact magnetoresistance on the bulk scattering spin asymmetry in CoFe alloys with oxidation impurities

NASA Astrophysics Data System (ADS)

Shiokawa, Yohei; Jung, JinWon; Otsuka, Takahiko; Sahashi, Masashi

2015-08-01

Nano-contact magnetoresistance (NCMR) spin-valves (SVs) using an AlOx nano-oxide-layer (NOL) have numerous nanocontacts in the thin AlOx oxide layer. The NCMR theoretically depends on the bulk scattering spin asymmetry ( β) of the ferromagnetic material in the nanocontacts. To determine the relationship between NCMR and β, we investigated the dependence of NCMR on the composition of the ferromagnetic material Co1-xFex. The samples were annealed at 270 °C and 380 °C to enhance the MR ratio. For both annealing temperatures, the magnetorsistance ratio in the low-resistance area product region at less than 1 Ω μm2 was maximized for Co0.5Fe0.5. To evaluate β exactly, we fabricated current-perpendicular-to-plane giant magnetoresistance SVs with Co1-xFex/Cu/Co1-xFex layers and used Valet and Fert's theory to solve the diffusion equation of the spin accumulation for a ferromagnetic layer/non-ferromagnetic layer of five layers with a finite diffusion length. The evaluated β for Co1-xFex was also maximized for Co0.5Fe0.5. Additionally, to determine the difference between the experimental MR ratio of NCMR SVs and the theoretical MR ratio, we fabricated Co0.5Fe0.5 with oxygen impurities and estimated the decrease in β with increasing oxygen impurity concentration. Our Co0.5Fe0.5 nano-contacts fabricated using ion-assisted oxidation may contain oxygen impurities, and the oxygen impurities might cause a decrease in β and the MR ratio.

Mass production of polymer nano-wires filled with metal nano-particles.

PubMed

Lomadze, Nino; Kopyshev, Alexey; Bargheer, Matias; Wollgarten, Markus; Santer, Svetlana

2017-08-17

Despite the ongoing progress in nanotechnology and its applications, the development of strategies for connecting nano-scale systems to micro- or macroscale elements is hampered by the lack of structural components that have both, nano- and macroscale dimensions. The production of nano-scale wires with macroscale length is one of the most interesting challenges here. There are a lot of strategies to fabricate long nanoscopic stripes made of metals, polymers or ceramics but none is suitable for mass production of ordered and dense arrangements of wires at large numbers. In this paper, we report on a technique for producing arrays of ordered, flexible and free-standing polymer nano-wires filled with different types of nano-particles. The process utilizes the strong response of photosensitive polymer brushes to irradiation with UV-interference patterns, resulting in a substantial mass redistribution of the polymer material along with local rupturing of polymer chains. The chains can wind up in wires of nano-scale thickness and a length of up to several centimeters. When dispersing nano-particles within the film, the final arrangement is similar to a core-shell geometry with mainly nano-particles found in the core region and the polymer forming a dielectric jacket.

Electron transport in nano-scaled piezoelectronic devices

NASA Astrophysics Data System (ADS)

Jiang, Zhengping; Kuroda, Marcelo A.; Tan, Yaohua; Newns, Dennis M.; Povolotskyi, Michael; Boykin, Timothy B.; Kubis, Tillmann; Klimeck, Gerhard; Martyna, Glenn J.

2013-05-01

The Piezoelectronic Transistor (PET) has been proposed as a post-CMOS device for fast, low-power switching. In this device, the piezoresistive channel is metalized via the expansion of a relaxor piezoelectric element to turn the device on. The mixed-valence compound SmSe is a good choice of PET channel material because of its isostructural pressure-induced continuous metal insulator transition, which is well characterized in bulk single crystals. Prediction and optimization of the performance of a realistic, nano-scaled PET based on SmSe requires the understanding of quantum confinement, tunneling, and the effect of metal interface. In this work, a computationally efficient empirical tight binding (ETB) model is developed for SmSe to study quantum transport in these systems and the scaling limit of PET channel lengths. Modulation of the SmSe band gap under pressure is successfully captured by ETB, and ballistic conductance shows orders of magnitude change under hydrostatic strain, supporting operability of the PET device at nanoscale.

Nano-scaled graphene platelets with a high length-to-width aspect ratio

DOEpatents

Zhamu, Aruna; Guo, Jiusheng; Jang, Bor Z.

2010-09-07

This invention provides a nano-scaled graphene platelet (NGP) having a thickness no greater than 100 nm and a length-to-width ratio no less than 3 (preferably greater than 10). The NGP with a high length-to-width ratio can be prepared by using a method comprising (a) intercalating a carbon fiber or graphite fiber with an intercalate to form an intercalated fiber; (b) exfoliating the intercalated fiber to obtain an exfoliated fiber comprising graphene sheets or flakes; and (c) separating the graphene sheets or flakes to obtain nano-scaled graphene platelets. The invention also provides a nanocomposite material comprising an NGP with a high length-to-width ratio. Such a nanocomposite can become electrically conductive with a small weight fraction of NGPs. Conductive composites are particularly useful for shielding of sensitive electronic equipment against electromagnetic interference (EMI) or radio frequency interference (RFI), and for electrostatic charge dissipation.

A respiratory chain controlled signal transduction cascade in the mitochondrial intermembrane space mediates hydrogen peroxide signaling

PubMed Central

Patterson, Heide Christine; Gerbeth, Carolin; Thiru, Prathapan; Vögtle, Nora F.; Knoll, Marko; Shahsafaei, Aliakbar; Samocha, Kaitlin E.; Huang, Cher X.; Harden, Mark Michael; Song, Rui; Chen, Cynthia; Kao, Jennifer; Shi, Jiahai; Salmon, Wendy; Shaul, Yoav D.; Stokes, Matthew P.; Silva, Jeffrey C.; Bell, George W.; MacArthur, Daniel G.; Ruland, Jürgen; Meisinger, Chris; Lodish, Harvey F.

2015-01-01

Reactive oxygen species (ROS) such as hydrogen peroxide (H2O2) govern cellular homeostasis by inducing signaling. H2O2 modulates the activity of phosphatases and many other signaling molecules through oxidation of critical cysteine residues, which led to the notion that initiation of ROS signaling is broad and nonspecific, and thus fundamentally distinct from other signaling pathways. Here, we report that H2O2 signaling bears hallmarks of a regular signal transduction cascade. It is controlled by hierarchical signaling events resulting in a focused response as the results place the mitochondrial respiratory chain upstream of tyrosine-protein kinase Lyn, Lyn upstream of tyrosine-protein kinase SYK (Syk), and Syk upstream of numerous targets involved in signaling, transcription, translation, metabolism, and cell cycle regulation. The active mediators of H2O2 signaling colocalize as H2O2 induces mitochondria-associated Lyn and Syk phosphorylation, and a pool of Lyn and Syk reside in the mitochondrial intermembrane space. Finally, the same intermediaries control the signaling response in tissues and species responsive to H2O2 as the respiratory chain, Lyn, and Syk were similarly required for H2O2 signaling in mouse B cells, fibroblasts, and chicken DT40 B cells. Consistent with a broad role, the Syk pathway is coexpressed across tissues, is of early metazoan origin, and displays evidence of evolutionary constraint in the human. These results suggest that H2O2 signaling is under control of a signal transduction pathway that links the respiratory chain to the mitochondrial intermembrane space-localized, ubiquitous, and ancient Syk pathway in hematopoietic and nonhematopoietic cells. PMID:26438848

A respiratory chain controlled signal transduction cascade in the mitochondrial intermembrane space mediates hydrogen peroxide signaling.

PubMed

Patterson, Heide Christine; Gerbeth, Carolin; Thiru, Prathapan; Vögtle, Nora F; Knoll, Marko; Shahsafaei, Aliakbar; Samocha, Kaitlin E; Huang, Cher X; Harden, Mark Michael; Song, Rui; Chen, Cynthia; Kao, Jennifer; Shi, Jiahai; Salmon, Wendy; Shaul, Yoav D; Stokes, Matthew P; Silva, Jeffrey C; Bell, George W; MacArthur, Daniel G; Ruland, Jürgen; Meisinger, Chris; Lodish, Harvey F

2015-10-20

Reactive oxygen species (ROS) such as hydrogen peroxide (H2O2) govern cellular homeostasis by inducing signaling. H2O2 modulates the activity of phosphatases and many other signaling molecules through oxidation of critical cysteine residues, which led to the notion that initiation of ROS signaling is broad and nonspecific, and thus fundamentally distinct from other signaling pathways. Here, we report that H2O2 signaling bears hallmarks of a regular signal transduction cascade. It is controlled by hierarchical signaling events resulting in a focused response as the results place the mitochondrial respiratory chain upstream of tyrosine-protein kinase Lyn, Lyn upstream of tyrosine-protein kinase SYK (Syk), and Syk upstream of numerous targets involved in signaling, transcription, translation, metabolism, and cell cycle regulation. The active mediators of H2O2 signaling colocalize as H2O2 induces mitochondria-associated Lyn and Syk phosphorylation, and a pool of Lyn and Syk reside in the mitochondrial intermembrane space. Finally, the same intermediaries control the signaling response in tissues and species responsive to H2O2 as the respiratory chain, Lyn, and Syk were similarly required for H2O2 signaling in mouse B cells, fibroblasts, and chicken DT40 B cells. Consistent with a broad role, the Syk pathway is coexpressed across tissues, is of early metazoan origin, and displays evidence of evolutionary constraint in the human. These results suggest that H2O2 signaling is under control of a signal transduction pathway that links the respiratory chain to the mitochondrial intermembrane space-localized, ubiquitous, and ancient Syk pathway in hematopoietic and nonhematopoietic cells.

Direct determination of three-phase contact line properties on nearly molecular scale

DOE PAGES

Winkler, P. M.; McGraw, R. L.; Bauer, P. S.; ...

2016-05-17

Wetting phenomena in multi-phase systems govern the shape of the contact line which separates the different phases. For liquids in contact with solid surfaces wetting is typically described in terms of contact angle. While in macroscopic systems the contact angle can be determined experimentally, on the molecular scale contact angles are hardly accessible. Here we report the first direct experimental determination of contact angles as well as contact line curvature on a scale of the order of 1nm. For water nucleating heterogeneously on Ag nanoparticles we find contact angles around 15 degrees compared to 90 degrees for the corresponding macroscopicallymore » measured equilibrium angle. The obtained microscopic contact angles can be attributed to negative line tension in the order of –10 –10 J/m that becomes increasingly dominant with increasing curvature of the contact line. Furthermore, these results enable a consistent theoretical description of heterogeneous nucleation and provide firm insight to the wetting of nanosized objects.« less

Wafer-scale aluminum nano-plasmonics

NASA Astrophysics Data System (ADS)

George, Matthew C.; Nielson, Stew; Petrova, Rumyana; Frasier, James; Gardner, Eric

2014-09-01

The design, characterization, and optical modeling of aluminum nano-hole arrays are discussed for potential applications in surface plasmon resonance (SPR) sensing, surface-enhanced Raman scattering (SERS), and surface-enhanced fluorescence spectroscopy (SEFS). In addition, recently-commercialized work on narrow-band, cloaked wire grid polarizers composed of nano-stacked metal and dielectric layers patterned over 200 mm diameter wafers for projection display applications is reviewed. The stacked sub-wavelength nanowire grid results in a narrow-band reduction in reflectance by 1-2 orders of magnitude, which can be tuned throughout the visible spectrum for stray light control.

Nuclear Reactions in Micro/Nano-Scale Metal Particles

NASA Astrophysics Data System (ADS)

Kim, Y. E.

2013-03-01

Low-energy nuclear reactions in micro/nano-scale metal particles are described based on the theory of Bose-Einstein condensation nuclear fusion (BECNF). The BECNF theory is based on a single basic assumption capable of explaining the observed LENR phenomena; deuterons in metals undergo Bose-Einstein condensation. The BECNF theory is also a quantitative predictive physical theory. Experimental tests of the basic assumption and theoretical predictions are proposed. Potential application to energy generation by ignition at low temperatures is described. Generalized theory of BECNF is used to carry out theoretical analyses of recently reported experimental results for hydrogen-nickel system.

On the Size Dependence of Molar and Specific Properties of Independent Nano-phases and Those in Contact with Other Phases

NASA Astrophysics Data System (ADS)

Kaptay, George

2018-05-01

Nano-materials are materials with at least one nano-phase. A nano-phase is a phase with at least one of its dimensions below 100 nm. It is shown here that nano-phases have at least 1% of their atoms along their surface layer. The ratio of surface atoms is proportional to the specific surface area of the phase, defined as the ratio of its surface area to its volume. Each specific/molar property has its bulk value and its surface value for the given phase, being always different, as the energetic states of the atoms in the bulk and in the surface layer of a phase are different. The average specific/molar property of a nano-phase is modeled here as a linear combination of the bulk and surface values of the same property, scaled with the ratio of the surface atoms. That makes the performance of all nano-phases proportional to their specific surface area. As the characteristic size of the nano-phase is inversely proportional to its specific surface area, all specific/molar properties of nano-phases are inversely proportional to the characteristic size of the phase. This is applied to the size dependence of the molar Gibbs energy of the nano-phase, which appears to be in agreement with the thermodynamics of Gibbs. This agreement proves the general validity of the present model on the size dependence of the specific/molar properties of independent nano-phases. It is shown that the properties of nano-phases are different for independent nano-phases (surrounded only by their equilibrium vapor phase) and for nano-phases in multi-phase situations, such as a liquid nano-droplet in the sessile drop configuration.

Stabilizing the body centered cubic crystal in titanium alloys by a nano-scale concentration modulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, H. L.; Shah, S. A. A.; Hao, Y. L.

It is well-known that the body centered cubic (bcc) crystal in titanium alloys reaches its stability limit as the electron-to-atom (e/a) ratio of the alloy drops down to ~4.24. This critical value, however, is much higher than that of a multifunctional bcc type alloy (e/a = 4.15). Here we demonstrate that a nano-scale concentration modulation created by spinodal decomposition is what stabilizes the bcc crystal of the alloy. Aided by such a nano-scale concentration heterogeneity, unexpected properties from its chemically homogeneous counterpart are obtained. This provides a new strategy to design functional titanium alloys by tuning the spinodal decomposition.

The Antibiofilm efficacy of nitric oxide on soft contact lenses.

PubMed

Kim, Dong Ju; Park, Joo-Hee; Kim, Marth; Park, Choul Yong

2017-11-21

To investigate the antibiofilm efficacy of nitric oxide (NO) on soft contact lenses. Nitrite (NO precursor) release from various concentrations (0-1000 μM) of sodium nitrite (NaNO 2, NO donor) was measured by Griess Assay. Cell viability assay was performed using human corneal epithelial cell under various concentration (0-1000 μM) of NaNO 2 . Biofilm formation on soft contact lenses was achieved by adding Staphylococcus aureus or Pseudomonas aeruginosa to the culture media. Various concentrations of NaNO 2 (0-1000 μM) were added to the culture media, each containing soft contact lens. After incubation in NaNO 2 containing culture media for 1, 3, or 7 days, each contact lens was transferred to a fresh, bacteria-free media without NaNO 2 . The bacteria in the biofilm were dispersed in the culture media for planktonic growth. After reculturing the lenses in the fresh media for 24 h, optical density (OD) of media was measured at 600 nm and colony forming unit (CFU) was counted by spreading media on tryptic soy agar plate for additional 18 h. Nitrite release from NaNO 2 showed dose-dependent suppressive effect on biofilm formation. Most nitrite release from NaNO 2 tended to occur within 30 min. The viability of human corneal epithelial cells was well maintained at tested NaNO 2 concentrations. The bacterial CFU and OD showed dose-dependent decrease in the NaNO 2 treated samples on days 1, 3 and 7 for both Staphylococcus aureus and Pseudomonas aeruginosa. NO successfully inhibited the biofilm formation by Staphylococcus aureus or Pseudomonas aeruginosa on soft contact lenses in dose-dependent manner.

On the physically based modeling of surface tension and moving contact lines with dynamic contact angles on the continuum scale

NASA Astrophysics Data System (ADS)

Huber, M.; Keller, F.; Säckel, W.; Hirschler, M.; Kunz, P.; Hassanizadeh, S. M.; Nieken, U.

2016-04-01

The description of wetting phenomena is a challenging problem on every considerable length-scale. The behavior of interfaces and contact lines on the continuum scale is caused by intermolecular interactions like the Van der Waals forces. Therefore, to describe surface tension and the resulting dynamics of interfaces and contact lines on the continuum scale, appropriate formulations must be developed. While the Continuum Surface Force (CSF) model is well-engineered for the description of interfaces, there is still a lack of treatment of contact lines, which are defined by the intersection of an ending fluid interface and a solid boundary surface. In our approach we use a balance equation for the contact line and extend the Navier-Stokes equations in analogy to the extension of a two-phase interface in the CSF model. Since this model depicts a physically motivated approach on the continuum scale, no fitting parameters are introduced and the deterministic description leads to a dynamical evolution of the system. As verification of our theory, we show a Smoothed Particle Hydrodynamics (SPH) model and simulate the evolution of droplet shapes and their corresponding contact angles.

Tribological Properties of CrAlN and TiN Coatings Tested in Nano- and Micro-scale Laboratory Wear Tests

NASA Astrophysics Data System (ADS)

Hong, Ling; Bian, Guangdong; Hu, Shugen; Wang, Linlin; Dacosta, Herbert

2015-07-01

We investigated the tribological properties of CrAlN and TiN coatings produced by electron beam plasma-assisted physical vapor deposition by nano- and micro-scale wear tests. For comparison, we also conducted nano-indentation, nano-scanning wear tests, and pin-on-disk tribotests on uncoated M2 steel. The results indicate that, after nano-scale sliding tests against diamond indenter and pin-on-disk tests against ceramic alumina counterface pins, the CrAlN coating presents superior abrasive wear resistance compared to the TiN-coated and uncoated M2 steel samples. Against aluminum counterface, aluminum is more prone to attach on the CrAlN coating surface compared to TiN coating, but no apparent adhesive wear was observed, which has occurred on the TiN coating.

Thermal and frictional performance evaluation of nano lubricant with multi wall carbon nano tubes (MWCNTs) as nano-additive

NASA Astrophysics Data System (ADS)

Lijesh K., P.; Kumar, Deepak; Muzakkir S., M.; Hirani, Harish

2018-05-01

A Fluid Film Bearings (FFBs) operating in hydrodynamic boundary regime can provide moderate load carrying capacity, negligible wear and friction. However in extreme operating conditions i.e. at high load and low speed, asperities of journal and bearing surfaces come in contact with each other resulting in high wear and friction. During the contact of the asperities, the temperature of the lubricant increases due to frictional heating, resulting in reduction of the viscosity of lubricant. Variation of lubricant viscosity results in low load carrying capacity of the FFB and therefore resulting in detoriation of FFB performance. In the present work it is hypothesized that, by adding multi-functional Multi Wall Carbon Nano-Tubes (MWCNT) (having high thermal conductivity and anti-friction properties) as nano-additive in the base mineral oil, the aforementioned problems can be overcome. To validate the proposed hypothesis, five different samples of lubricant is considered: Sample 1: Base oil, Sample 2: Base oil +0.05% MWCNT, Sample 3: Base oil +0.05% MWCNT +0.5%surfactant, Sample 4: Base oil +0.1% MWCNT +0.5% surfactant, and Sample 5: Base oil +0.15% MWCNT +0.5%surfactant. To evaluate the performance of the developed lubricants, experiments were performed on the reduced scale conformal block on disc test setup. The experimental condition and dimension of the block and disc were decide for the Sommerfeld number equal to 0.0025, which indicates mixed lubrication regime. The performance of lubricant is evaluated by measuring the frictional force and temperature rise of the lubricant during the experiment.

Scaling properties of ballistic nano-transistors

PubMed Central

2011-01-01

Recently, we have suggested a scale-invariant model for a nano-transistor. In agreement with experiments a close-to-linear thresh-old trace was found in the calculated ID - VD-traces separating the regimes of classically allowed transport and tunneling transport. In this conference contribution, the relevant physical quantities in our model and its range of applicability are discussed in more detail. Extending the temperature range of our studies it is shown that a close-to-linear thresh-old trace results at room temperatures as well. In qualitative agreement with the experiments the ID - VG-traces for small drain voltages show thermally activated transport below the threshold gate voltage. In contrast, at large drain voltages the gate-voltage dependence is weaker. As can be expected in our relatively simple model, the theoretical drain current is larger than the experimental one by a little less than a decade. PMID:21711899

Developing Sensitive and Selective Nanosensors: A Single Molecule - Multiple Excitation Source Approach. Altairnano Lithium Ion Nano-scaled Titanate Oxide Cell and Module Abuse Testing

DTIC Science & Technology

2012-03-13

Source Approach Part II. Altairnano Lithium Ion Nano-scaled Titanate Oxide Cell and Module Abuse Testing 14. ABSTRACT 16. SECURITY CLASSIFICATION OF...Lithium Ion Nano-scaled Titanate Oxide Cell and Module Abuse Testing Report Title ABSTRACT This final report for Contract W911NF-09-C-0135 transmits the...prototype development. The second (Part II.) is "Altairnano Lithium Ion Nano-scaled Titanate Oxide Cell and Module Abuse Test Report". The

Moving Contact Lines: Linking Molecular Dynamics and Continuum-Scale Modeling.

PubMed

Smith, Edward R; Theodorakis, Panagiotis E; Craster, Richard V; Matar, Omar K

2018-05-17

Despite decades of research, the modeling of moving contact lines has remained a formidable challenge in fluid dynamics whose resolution will impact numerous industrial, biological, and daily life applications. On the one hand, molecular dynamics (MD) simulation has the ability to provide unique insight into the microscopic details that determine the dynamic behavior of the contact line, which is not possible with either continuum-scale simulations or experiments. On the other hand, continuum-based models provide a link to the macroscopic description of the system. In this Feature Article, we explore the complex range of physical factors, including the presence of surfactants, which governs the contact line motion through MD simulations. We also discuss links between continuum- and molecular-scale modeling and highlight the opportunities for future developments in this area.

3D positioning scheme exploiting nano-scale IR-UWB orthogonal pulses.

PubMed

Kim, Nammoon; Kim, Youngok

2011-10-04

In these days, the development of positioning technology for realizing ubiquitous environments has become one of the most important issues. The Global Positioning System (GPS) is a well-known positioning scheme, but it is not suitable for positioning in in-door/building environments because it is difficult to maintain line-of-sight condition between satellites and a GPS receiver. To such problem, various positioning methods such as RFID, WLAN, ZigBee, and Bluetooth have been developed for indoor positioning scheme. However, the majority of positioning schemes are focused on the two-dimension positioning even though three-dimension (3D) positioning information is more useful especially in indoor applications, such as smart space, U-health service, context aware service, etc. In this paper, a 3D positioning system based on mutually orthogonal nano-scale impulse radio ultra-wideband (IR-UWB) signals and cross array antenna is proposed. The proposed scheme uses nano-scale IR-UWB signals providing fine time resolution and high-resolution multiple signal specification algorithm for the time-of-arrival and the angle-of-arrival estimation. The performance is evaluated over various IEEE 802.15.4a channel models, and simulation results show the effectiveness of proposed scheme.

Modeling the Charge Transport in Graphene Nano Ribbon Interfaces for Nano Scale Electronic Devices

NASA Astrophysics Data System (ADS)

Kumar, Ravinder; Engles, Derick

2015-05-01

In this research work we have modeled, simulated and compared the electronic charge transport for Metal-Semiconductor-Metal interfaces of Graphene Nano Ribbons (GNR) with different geometries using First-Principle calculations and Non-Equilibrium Green's Function (NEGF) method. We modeled junctions of Armchair GNR strip sandwiched between two Zigzag strips with (Z-A-Z) and Zigzag GNR strip sandwiched between two Armchair strips with (A-Z-A) using semi-empirical Extended Huckle Theory (EHT) within the framework of Non-Equilibrium Green Function (NEGF). I-V characteristics of the interfaces were visualized for various transport parameters. The distinct changes in conductance and I-V curves reported as the Width across layers, Channel length (Central part) was varied at different bias voltages from -1V to 1 V with steps of 0.25 V. From the simulated results we observed that the conductance through A-Z-A graphene junction is in the range of 10-13 Siemens whereas the conductance through Z-A-Z graphene junction is in the range of 10-5 Siemens. These suggested conductance controlled mechanisms for the charge transport in the graphene interfaces with different geometries is important for the design of graphene based nano scale electronic devices like Graphene FETs, Sensors.

Nano-Scale Fabrication Using Optical-Near-Field

NASA Astrophysics Data System (ADS)

Yatsui, Takashi; Ohtsu, Motoichi

This paper reviews the specific nature of nanophotonics, i.e., a novel optical nano-technology, utilizing dressed photon excited in the nano-material. As examples of nanophotnic fabrication, optical near-field etching and increased spatial homogeneity of contents in compound semiconductors is demonstrated with a self-organized manner.

Synthesis of Nano-Scale Fast Ion Conducting Cubic Li7La3Zr2O12

DTIC Science & Technology

2013-09-25

offer the flexibility to make nano-dimensional particles with high sinterability nor the ability to coat/protect electrode powders. By developing a...sintering temperature are needed. One possible approach is to use small particles , such as nano-scale particles , that can be sintered at lower temperatures...matrix to suppress Li dendrite penetration. By developing a sol–gel process, the LLZO particle size can be precisely tuned, from the nanometer to the

Effects of contact shape on the scaling of biological attachments

NASA Astrophysics Data System (ADS)

Spolenak, Ralph; Gorb, Stanislav; Gao, Huajian; Arzt, Eduard

2005-02-01

Adhesion of biological systems has recently received much research attention: the survival of organisms ranging from single cells and mussels to insects, spiders and geckos relies crucially on their mechanical interaction with their environments. For spiders, lizards and possible other 'dry' adhesive systems, explanations for adhesion are based on van der Waals interaction, and the adhesion of single-contact elements has been described by the classical Johnson-Kendall-Roberts (JKR) model derived for spherical contacts. However, real biological contacts display a variety of shapes and only rarely resemble a hemisphere. Here, we theoretically assess the influence of various contact shapes on the pull-off force for single contacts as well as their scaling potential in contact arrays. It is concluded that other shapes, such as a toroidal contact geometry, should lead to better attachment; such geometries are observed in our microscopic investigations of hair-tip shapes in beetles and flies.

The viability and performance characterization of nano scale energetic materials on a semiconductor bridge (SCB)

NASA Astrophysics Data System (ADS)

Strohm, Gianna Sophia

The move from conventional energetic composites to nano scale energetic mixtures (nano energetics) has shown dramatic improvement in energy release rate and sensitivity to ignition. A possible application of nano energetics is on a semiconductor bridge (SCB). An SCB typically requires a tenth of the energy input as compared to a bridge wire design with the same no-fire and is capable of igniting in tens of microseconds. For very low energy applications, SCBs can be manufactured to extremely small sizes and it is necessary to find materials with particle sizes that are even smaller to function. Reactive particles of comparable size to the bridge can lead to problems with ignition reliability for small bridges. Nano-energetic composites and the use of SCBs have been significantly studied individually, however, the process of combining nano energetics with an SCB has not been investigated extensively and is the focus of this work. Goals of this study are to determine if nano energetics can be used with SCBs to further reduce the minimum energy required and improve reliability. The performance of nano-scale aluminum (nAl) and bismuth oxide (Bi2O3) with nitrocellulose (NC), Fluorel(TM) FC 2175 (chemically equivalent to VitonRTM) and Glycidyl Azide Polymer (GAP) as binders where quantified initially using the SenTest(TM) algorithm at three weight fractions (5, 7, and 9%) of binder. The threshold energy was calculated and compared to previous data using conventional materials such as zirconium potassium chlorate (ZPC), mercuric 5-Nitrotetrazol (DXN-1) and titanium sub-hydride potassium per-chlorate (TSPP). It was found that even though there where only slight differences in performance between the binders with nAl/Bi2O 3 at any of the three binder weight fractions, the results show that these nano energetic materials require about half of the threshold energy compared to conventional materials using an SCB with an 84x42 mum bridge. Binder limit testing was conducted to

Molecular Imaging of Kerogen and Minerals in Shale Rocks across Micro- and Nano- Scales

NASA Astrophysics Data System (ADS)

Hao, Z.; Bechtel, H.; Sannibale, F.; Kneafsey, T. J.; Gilbert, B.; Nico, P. S.

2016-12-01

Fourier transform infrared (FTIR) spectroscopy is a reliable and non-destructive quantitative method to evaluate mineralogy and kerogen content / maturity of shale rocks, although it is traditionally difficult to assess the organic and mineralogical heterogeneity at micrometer and nanometer scales due to the diffraction limit of the infrared light. However, it is truly at these scales that the kerogen and mineral content and their formation in share rocks determines the quality of shale gas reserve, the gas flow mechanisms and the gas production. Therefore, it's necessary to develop new approaches which can image across both micro- and nano- scales. In this presentation, we will describe two new molecular imaging approaches to obtain kerogen and mineral information in shale rocks at the unprecedented high spatial resolution, and a cross-scale quantitative multivariate analysis method to provide rapid geochemical characterization of large size samples. The two imaging approaches are enhanced at nearfield respectively by a Ge-hemisphere (GE) and by a metallic scanning probe (SINS). The GE method is a modified microscopic attenuated total reflectance (ATR) method which rapidly captures a chemical image of the shale rock surface at 1 to 5 micrometer resolution with a large field of view of 600 X 600 micrometer, while the SINS probes the surface at 20 nm resolution which provides a chemically "deconvoluted" map at the nano-pore level. The detailed geochemical distribution at nanoscale is then used to build a machine learning model to generate self-calibrated chemical distribution map at micrometer scale with the input of the GE images. A number of geochemical contents across these two important scales are observed and analyzed, including the minerals (oxides, carbonates, sulphides), the organics (carbohydrates, aromatics), and the absorbed gases. These approaches are self-calibrated, optics friendly and non-destructive, so they hold the potential to monitor shale gas

Experimental Study of Static Contact-angle on Peak-like Microstructural Surfaces Produced by PIII Technology

NASA Astrophysics Data System (ADS)

Yang, Runhua; Yang, Lixin

2018-06-01

Plasma immersion ion implantation (PIII) was used to fabricate micro/nano structures on monocrystalline Si surfaces with different ratios of mixed gases (SF6/O2). The micro/nano structures on the surfaces of the sample were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The results showed that with increasing ratio of mixed gases (SF6/O2), the height of the micro/nano structures first increased and then decreased. Contact-angle measurements indicated that the surfaces' micro/nano structures have an obvious effect on the contact-angle, and could cause a change in surface wettability. The theoretical analysis of contact-angle showed that the Wenzel and Cassie theories cannot predict the contact-angle of a roughened surface accurately, and should be corrected for practical applications using an actual model. Moreover, the contact-angle first increased and then decreased with increasing ratio of mixed gases (SF6/O2), which is in accordance with the change of the height of micro/nano structures.

Ignition dynamics and activation energies of metallic thermites: From nano- to micron-scale particulate composites

NASA Astrophysics Data System (ADS)

Hunt, Emily M.; Pantoya, Michelle L.

2005-08-01

Ignition behaviors associated with nano- and micron-scale particulate composite thermites were studied experimentally and modeled theoretically. The experimental analysis utilized a CO2 laser ignition apparatus to ignite the front surface of compacted nickel (Ni) and aluminum (Al) pellets at varying heating rates. Ignition delay time and ignition temperature as a function of both Ni and Al particle size were measured using high-speed imaging and microthermocouples. The apparent activation energy was determined from this data using a Kissinger isoconversion method. This study shows that the activation energy is significantly lower for nano- compared with micron-scale particulate media (i.e., as low as 17.4 compared with 162.5kJ /mol, respectively). Two separate Arrhenius-type mathematical models were developed that describe ignition in the nano- and the micron-composite thermites. The micron-composite model is based on a heat balance while the nanocomposite model incorporates the energy of phase transformation in the alumina shell theorized to be an initiating step in the solid-solid diffusion reaction and uniquely appreciable in nanoparticle media. These models were found to describe the ignition of the Ni /Al alloy for a wide range of heating rates.

Feasibility of Pb phytoextraction using nano-materials assisted ryegrass: Results of a one-year field-scale experiment.

PubMed

Liang, Shu-Xuan; Jin, Yu; Liu, Wei; Li, Xiliang; Shen, Shi-Gang; Ding, Ling

2017-04-01

The effect of the combined application of nano-hydroxyapatite (NHAP) or nano-carbon black (NCB) on the phytoextraction of Pb by ryegrass was investigated as an enhanced remediation technique for soils by field-scale experiment. After the addition of 0.2% NHAP or NCB to the soil, temporal variation of the uptake of Pb in aboveground parts and roots were observed. Ryegrass shoot concentrations of Pb were lower with nano-materials application than without nano-materials for the first month. However, the shoot concentrations of Pb were significantly increased with nano-materials application, in particular NHAP groups. The ryegrass root concentrations of Pb were lower with nano-materials application for the first month. These results indicated that nano-materials had significant effects on stabilization of lead, especially at the beginning of the experiment. Along with the experimental proceeding, phytotoxicity was alleviated after the incorporation of nano-materials. The ryegrass biomass was significantly higher with nano-materials application. Consequently, the Pb phytoextraction potential of ryegrass significantly increased with nano-materials application compared to the gounps without nano-materials application. The total removal rates of soil Pb were higher after combined application of NHAP than NCB. NHAP is more suitable than NCB for in-situ remediation of Pb-contaminated soils. The ryegrass translocation factor exhibited a marked increase with time. It was thought that the major role of NHP and NBA might be to alleviate the Pb phytotoxicity and increase biomass of plants. Copyright © 2016 Elsevier Ltd. All rights reserved.

Oil Contact Angles in a Water-Decane-Silicon Dioxide System: Effects of Surface Charge

NASA Astrophysics Data System (ADS)

Xu, Shijing; Wang, Jingyao; Wu, Jiazhong; Liu, Qingjie; Sun, Chengzhen; Bai, Bofeng

2018-04-01

Oil wettability in the water-oil-rock systems is very sensitive to the evolution of surface charges on the rock surfaces induced by the adsorption of ions and other chemical agents in water flooding. Through a set of large-scale molecular dynamics simulations, we reveal the effects of surface charge on the oil contact angles in an ideal water-decane-silicon dioxide system. The results show that the contact angles of oil nano-droplets have a great dependence on the surface charges. As the surface charge density exceeds a critical value of 0.992 e/nm2, the contact angle reaches up to 78.8° and the water-wet state is very apparent. The variation of contact angles can be confirmed from the number density distributions of oil molecules. With increasing the surface charge density, the adsorption of oil molecules weakens and the contact areas between nano-droplets and silicon dioxide surface are reduced. In addition, the number density distributions, RDF distributions, and molecular orientations indicate that the oil molecules are adsorbed on the silicon dioxide surface layer-by-layer with an orientation parallel to the surface. However, the layered structure of oil molecules near the silicon dioxide surface becomes more and more obscure at higher surface charge densities.

Oil Contact Angles in a Water-Decane-Silicon Dioxide System: Effects of Surface Charge.

PubMed

Xu, Shijing; Wang, Jingyao; Wu, Jiazhong; Liu, Qingjie; Sun, Chengzhen; Bai, Bofeng

2018-04-19

Oil wettability in the water-oil-rock systems is very sensitive to the evolution of surface charges on the rock surfaces induced by the adsorption of ions and other chemical agents in water flooding. Through a set of large-scale molecular dynamics simulations, we reveal the effects of surface charge on the oil contact angles in an ideal water-decane-silicon dioxide system. The results show that the contact angles of oil nano-droplets have a great dependence on the surface charges. As the surface charge density exceeds a critical value of 0.992 e/nm 2 , the contact angle reaches up to 78.8° and the water-wet state is very apparent. The variation of contact angles can be confirmed from the number density distributions of oil molecules. With increasing the surface charge density, the adsorption of oil molecules weakens and the contact areas between nano-droplets and silicon dioxide surface are reduced. In addition, the number density distributions, RDF distributions, and molecular orientations indicate that the oil molecules are adsorbed on the silicon dioxide surface layer-by-layer with an orientation parallel to the surface. However, the layered structure of oil molecules near the silicon dioxide surface becomes more and more obscure at higher surface charge densities.

Turbulent Channel Flow Measurements with a Nano-scale Thermal Anemometry Probe

NASA Astrophysics Data System (ADS)

Bailey, Sean; Witte, Brandon

2014-11-01

Using a Nano-scale Thermal Anemometry Probe (NSTAP), streamwise velocity was measured in a turbulent channel flow wind tunnel at Reynolds numbers ranging from Reτ = 500 to Reτ = 4000 . Use of these probes results in the a sensing-length-to-viscous-length-scale ratio of just 5 at the highest Reynolds number measured. Thus measured results can be considered free of spatial filtering effects. Point statistics are compared to recently published DNS and LDV data at similar Reynolds numbers and the results are found to be in good agreement. However, comparison of the measured spectra provide further evidence of aliasing at long wavelengths due to application of Taylor's frozen flow hypothesis, with increased aliasing evident with increasing Reynolds numbers. In addition to conventional point statistics, the dissipative scales of turbulence are investigated with focus on the wall-dependent scaling. Results support the existence of a universal pdf distribution of these scales once scaled to account for large-scale anisotropy. This research is supported by KSEF Award KSEF-2685-RDE-015.

Evolution of the Contact Area with Normal Load for Rough Surfaces: from Atomic to Macroscopic Scales.

PubMed

Huang, Shiping

2017-11-13

The evolution of the contact area with normal load for rough surfaces has great fundamental and practical importance, ranging from earthquake dynamics to machine wear. This work bridges the gap between the atomic scale and the macroscopic scale for normal contact behavior. The real contact area, which is formed by a large ensemble of discrete contacts (clusters), is proven to be much smaller than the apparent surface area. The distribution of the discrete contact clusters and the interaction between them are key to revealing the mechanism of the contacting solids. To this end, Green's function molecular dynamics (GFMD) is used to study both how the contact cluster evolves from the atomic scale to the macroscopic scale and the interaction between clusters. It is found that the interaction between clusters has a strong effect on their formation. The formation and distribution of the contact clusters is far more complicated than that predicted by the asperity model. Ignorance of the interaction between them leads to overestimating the contacting force. In real contact, contacting clusters are smaller and more discrete due to the interaction between the asperities. Understanding the exact nature of the contact area with the normal load is essential to the following research on friction.

Evolution of the Contact Area with Normal Load for Rough Surfaces: from Atomic to Macroscopic Scales

NASA Astrophysics Data System (ADS)

Huang, Shiping

2017-11-01

The evolution of the contact area with normal load for rough surfaces has great fundamental and practical importance, ranging from earthquake dynamics to machine wear. This work bridges the gap between the atomic scale and the macroscopic scale for normal contact behavior. The real contact area, which is formed by a large ensemble of discrete contacts (clusters), is proven to be much smaller than the apparent surface area. The distribution of the discrete contact clusters and the interaction between them are key to revealing the mechanism of the contacting solids. To this end, Green's function molecular dynamics (GFMD) is used to study both how the contact cluster evolves from the atomic scale to the macroscopic scale and the interaction between clusters. It is found that the interaction between clusters has a strong effect on their formation. The formation and distribution of the contact clusters is far more complicated than that predicted by the asperity model. Ignorance of the interaction between them leads to overestimating the contacting force. In real contact, contacting clusters are smaller and more discrete due to the interaction between the asperities. Understanding the exact nature of the contact area with the normal load is essential to the following research on friction.

Development of a Cryostat to Characterize Nano-scale Superconducting Quantum Interference Devices

NASA Astrophysics Data System (ADS)

Longo, Mathew; Matheny, Matthew; Knudsen, Jasmine

2016-03-01

We have designed and constructed a low-noise vacuum cryostat to be used for the characterization of nano-scale superconducting quantum interference devices (SQUIDs). Such devices are very sensitive to magnetic fields and can measure changes in flux on the order of a single electron magnetic moment. As a part of the design process, we calculated the separation required between the cryogenic preamplifier and superconducting magnet, including a high-permeability magnetic shield, using a finite-element model of the apparatus. The cryostat comprises a vacuum cross at room temperature for filtered DC and shielded RF electrical connections, a thin-wall stainless steel support tube, a taper-sealed cryogenic vacuum can, and internal mechanical support and wiring for the nanoSQUID. The Dewar is modified with a room-temperature flange with a sliding seal for the cryostat. The flange supports the superconducting 3 Tesla magnet and thermometry wiring. Upon completion of the cryostat fabrication and Dewar modifications, operation of the nanoSQUIDs as transported from our collaborator's laboratory in Israel will be confirmed, as the lead forming the SQUID is sensitive to oxidation and the SQUIDs must be shipped in a vacuum container. After operation of the nanoSQUIDs is confirmed, the primary work of characterizing their high-speed properties will begin. This will include looking at the measurement of relaxation oscillations at high bandwidth in comparison to the theoretical predictions of the current model.

Challenges for the Modern Science in its Descend Towards Nano Scale

PubMed Central

Uskoković, Vuk

2013-01-01

The current rise in the interest in physical phenomena at nano spatial scale is described hereby as a natural consequence of the scientific progress in manipulation with matter with an ever higher sensitivity. The reason behind arising of the entirely new field of nanoscience is that the properties of nanostructured materials may significantly differ from their bulk counterparts and cannot be predicted by extrapolations of the size-dependent properties displayed by materials composed of microsized particles. It is also argued that although a material can comprise critical boundaries at the nano scale, this does not mean that it will inevitably exhibit properties that endow a nanomaterial. This implies that the attribute of “nanomaterial” can be used only in relation with a given property of interest. The major challenges faced with the expansion of resolution of the materials design, in terms of hardly reproducible experiments, are further discussed. It is claimed that owing to an unavoidable interference between the experimental system and its environment to which the controlling system belongs, an increased fineness of the experimental settings will lead to ever more difficulties in rendering them reproducible and controllable. Self-assembly methods in which a part of the preprogrammed scientific design is substituted with letting physical systems spontaneously evolve into attractive and functional structures is mentioned as one of the ways to overcome the problems inherent in synthetic approaches at the ultrafine scale. The fact that physical systems partly owe their properties to the interaction with their environment implies that each self-assembly process can be considered a co-assembly event. PMID:26491428

The scaling of contact rates with population density for the infectious disease models.

PubMed

Hu, Hao; Nigmatulina, Karima; Eckhoff, Philip

2013-08-01

Contact rates and patterns among individuals in a geographic area drive transmission of directly-transmitted pathogens, making it essential to understand and estimate contacts for simulation of disease dynamics. Under the uniform mixing assumption, one of two mechanisms is typically used to describe the relation between contact rate and population density: density-dependent or frequency-dependent. Based on existing evidence of population threshold and human mobility patterns, we formulated a spatial contact model to describe the appropriate form of transmission with initial growth at low density and saturation at higher density. We show that the two mechanisms are extreme cases that do not capture real population movement across all scales. Empirical data of human and wildlife diseases indicate that a nonlinear function may work better when looking at the full spectrum of densities. This estimation can be applied to large areas with population mixing in general activities. For crowds with unusually large densities (e.g., transportation terminals, stadiums, or mass gatherings), the lack of organized social contact structure deviates the physical contacts towards a special case of the spatial contact model - the dynamics of kinetic gas molecule collision. In this case, an ideal gas model with van der Waals correction fits well; existing movement observation data and the contact rate between individuals is estimated using kinetic theory. A complete picture of contact rate scaling with population density may help clarify the definition of transmission rates in heterogeneous, large-scale spatial systems. Copyright © 2013 The Authors. Published by Elsevier Inc. All rights reserved.

Evaporation of Liquid Droplet in Nano and Micro Scales from Statistical Rate Theory.

PubMed

Duan, Fei; He, Bin; Wei, Tao

2015-04-01

The statistical rate theory (SRT) is applied to predict the average evaporation flux of liquid droplet after the approach is validated in the sessile droplet experiments of the water and heavy water. The steady-state experiments show a temperature discontinuity at the evaporating interface. The average evaporation flux is evaluated by individually changing the measurement at a liquid-vapor interface, including the interfacial liquid temperature, the interfacial vapor temperature, the vapor-phase pressure, and the droplet size. The parameter study shows that a higher temperature jump would reduce the average evaporation flux. The average evaporation flux can significantly be influenced by the interfacial liquid temperature and the vapor-phase pressure. The variation can switch the evaporation into condensation. The evaporation flux is found to remain relative constant if the droplet is larger than a micro scale, while the smaller diameters in nano scale can produce a much higher evaporation flux. In addition, a smaller diameter of droplets with the same liquid volume has a larger surface area. It is suggested that the evaporation rate increases dramatically as the droplet shrinks into nano size.

Protein import and oxidative folding in the mitochondrial intermembrane space of intact mammalian cells

PubMed Central

Fischer, Manuel; Horn, Sebastian; Belkacemi, Anouar; Kojer, Kerstin; Petrungaro, Carmelina; Habich, Markus; Ali, Muna; Küttner, Victoria; Bien, Melanie; Kauff, Frank; Dengjel, Jörn; Herrmann, Johannes M.; Riemer, Jan

2013-01-01

Oxidation of cysteine residues to disulfides drives import of many proteins into the intermembrane space of mitochondria. Recent studies in yeast unraveled the basic principles of mitochondrial protein oxidation, but the kinetics under physiological conditions is unknown. We developed assays to follow protein oxidation in living mammalian cells, which reveal that import and oxidative folding of proteins are kinetically and functionally coupled and depend on the oxidoreductase Mia40, the sulfhydryl oxidase augmenter of liver regeneration (ALR), and the intracellular glutathione pool. Kinetics of substrate oxidation depends on the amount of Mia40 and requires tightly balanced amounts of ALR. Mia40-dependent import of Cox19 in human cells depends on the inner membrane potential. Our observations reveal considerable differences in the velocities of mitochondrial import pathways: whereas preproteins with bipartite targeting sequences are imported within seconds, substrates of Mia40 remain in the cytosol for several minutes and apparently escape premature degradation and oxidation. PMID:23676665

In situ microscopy of rapidly heated nano-Al and nano-Al/WO{sub 3} thermites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sullivan, Kyle T.; Zachariah, Michael R.; Chiou, Wen-An

2010-09-27

The initiation and reaction mechanism of nano-Al and nano-Al thermites in rapid heating environments is investigated in this work. A semiconductor-based grid/stage was used, capable of in situ heating of a sample from room temperature to 1473 K, and at a rate of 10{sup 6} K/s, inside an electron microscope. Nano-Al was rapidly heated in a transmission electron microscope, and before and after images indicate that the aluminum migrates through the shell, consistent with a diffusion-based mechanism. A nano-Al/WO{sub 3} composite was then heated in a scanning electron microscope. The results indicate that a reactive sintering mechanism is occurring formore » the nano-Al/WO{sub 3} thermite, as the products are found to be in surface contact and significantly deformed after the heating pulse.« less

Analytical study of nano-scale logical operations

NASA Astrophysics Data System (ADS)

Patra, Moumita; Maiti, Santanu K.

2018-07-01

A complete analytical prescription is given to perform three basic (OR, AND, NOT) and two universal (NAND, NOR) logic gates at nano-scale level using simple tailor made geometries. Two different geometries, ring-like and chain-like, are taken into account where in each case the bridging conductor is coupled to a local atomic site through a dangling bond whose site energy can be controlled by means of external gate electrode. The main idea is that when injecting electron energy matches with site energy of local atomic site transmission probability drops exactly to zero, whereas the junction exhibits finite transmission for other energies. Utilizing this prescription we perform logical operations, and, we strongly believe that the proposed results can be verified in laboratory. Finally, we numerically compute two-terminal transmission probability considering general models and the numerical results match exactly well with our analytical findings.

Nano-scale Characterization of Basalt - Quenched Lava and Reheated Products

NASA Astrophysics Data System (ADS)

Burkhard, D. J.; Wirth, R.

2001-12-01

In order to trace the mechanism of crystallization in basalt we investigated basalt lava from active Pu'u O'o, Kilauea, Hawaii with TEM. We considered (1) quenched melt (glass, obtained by dipping a hammer into the lava (April 1996) and subsequent quenching in air), and (2) that glass after reheating for 48 hr at 850° C, and (3) after reheating for 48 hr at 930° C. Previous investigations had illustrated interface-controlled growth of pyroxene and Fe-Ti oxides at 850° C and volumetric growth of these phases in addition to plagioclase above 920° C [1]. In general, (1) is a perfect glass to the nano-scale. Occasional inhomogeneities are identified as plagioclase. With a size of no more than approximately 100 unit cells, these "crystals" might be considered as nuclei. Dendrites of pyroxene, identified on the micron scale with back scattered electrons [1], occur as a sequence of slightly displaced plates with equal orientation on the nano-scale. HREM, diffraction pattern and EDS confirm that this is augite, in agreement with investigations on the micron-scale [1]. Fe-Ti oxides occur isolated in the matrix with a diameter less than 100 nm, in contrast to the micron-scale, where Fe-Ti oxides appear at the apices of augite. In (3) we find in addition plagioclase with thin lamellae, indicating twinning. In (3),augite contains lamellae parallel to (001), and they are identified as pigeonite by HREM and electron diffraction. Pigeonite lamellae occur also in (2), however, less developed. Electron diffraction suggests that reflections of augite correspond to the space group C 2/c, and of exsolved pigeonite to P 21/c, which is a low pigeonite. These exsolution phenomena are undistiguishable from what is usually observed in relation to high cooling rates [e.g. 2]. The stability of pigeonite at these temperatures suggests a Fe/Fe+Mg ratio above 0.6 for pyroxene in the quadilateral [3]. Microprobe analyses [1] suggest ratios of 0.4 to 0.5. [1] Burkhard D.J.M. (2001) J. Petrol

Three-dimensional direct laser written graphitic electrical contacts to randomly distributed components

NASA Astrophysics Data System (ADS)

Dorin, Bryce; Parkinson, Patrick; Scully, Patricia

2018-04-01

The development of cost-effective electrical packaging for randomly distributed micro/nano-scale devices is a widely recognized challenge for fabrication technologies. Three-dimensional direct laser writing (DLW) has been proposed as a solution to this challenge, and has enabled the creation of rapid and low resistance graphitic wires within commercial polyimide substrates. In this work, we utilize the DLW technique to electrically contact three fully encapsulated and randomly positioned light-emitting diodes (LEDs) in a one-step process. The resolution of the contacts is in the order of 20 μ m, with an average circuit resistance of 29 ± 18 kΩ per LED contacted. The speed and simplicity of this technique is promising to meet the needs of future microelectronics and device packaging.

Nano-scale characterization of nano-hydroxyapatite incorporated chitosan particles for bone repair.

PubMed

Gaihre, Bipin; Uswatta, Suren; Jayasuriya, Ambalangodage C

2018-05-01

In this study, injectable porous spherical particles were fabricated using chitosan (CS) biopolymer, sodium tripolyphosphate (TPP), and nano-hydroxyapatite (nHA). TPP was primarily used as an ionic crosslinker to crosslink 2% (w/v) CS droplets. 2% (w/v) nHA was used to prepare nHA incorporated particles. The surface morphological properties and nanomechanical properties such as topography, deformation, adhesion, and dissipation of CS particles with and without nHA were studied using contact mode and peakforce quantitative nanomechanical property mapping mode in atomic force microscopy. The nHA spots have higher density than CS which leads to higher forces acting on the probe tip and higher energy dissipation to lift the tip from nHA areas. The cumulative release data showed that about 87% of total BMP-2 encapsulated within the particles was released by third week of experiment period. Degradation study was conducted to understand how the particles degradation occurs in the presence of phosphate buffered saline with continues shaking in an incubator at 37° C. In addition, BMP-2 release from the 2% nHA/CS particles was studied over a three weeks period and found that BMP-2 release was governed by the simple diffusion rather than the degradation of particles. Copyright © 2018 Elsevier B.V. All rights reserved.

Multi-scale strategies for dealing with moving contact lines

NASA Astrophysics Data System (ADS)

Smith, Edward R.; Theodorakis, Panagiotis; Craster, Richard V.; Matar, Omar K.

2017-11-01

Molecular dynamics (MD) has great potential to elucidate the dynamics of the moving contact line. As a more fundamental model, it can provide a priori results for fluid-liquid interfaces, surface tension, viscosity, phase change, and near wall stick-slip behaviour which typically show very good agreement to experimental results. However, modelling contact line motion combines all this complexity in a single problem. In this talk, MD simulations of the contact line are compared to the experimental results obtained from studying the dynamics of a sheared liquid bridge. The static contact angles are correctly matched to the experimental data for a range of different electro-wetting results. The moving contact line results are then compared for each of these electro-wetting values. Despite qualitative agreement, there are notable differences between the simulation and experiments. Many MD simulation have studied contact lines, and the sheared liquid bridge, so it is of interest to review the limitations of this setup in light of this discrepancy. A number of factors are discussed, including the inter-molecular interaction model, molecular-scale surface roughness, model of electro-wetting and, perhaps most importantly, the limited system sizes possible using MD simulation. EPSRC, UK, MEMPHIS program Grant (EP/K003976/1), RAEng Research Chair (OKM).

Modeling and Characterization of Near-Crack-Tip Plasticity from Micro- to Nano-Scales

NASA Technical Reports Server (NTRS)

Glaessgen, Edward H.; Saether, Erik; Hochhalter, Jacob; Smith, Stephen W.; Ransom, Jonathan B.; Yamakov, Vesselin; Gupta, Vipul

2010-01-01

Methodologies for understanding the plastic deformation mechanisms related to crack propagation at the nano-, meso- and micro-length scales are being developed. These efforts include the development and application of several computational methods including atomistic simulation, discrete dislocation plasticity, strain gradient plasticity and crystal plasticity; and experimental methods including electron backscattered diffraction and video image correlation. Additionally, methodologies for multi-scale modeling and characterization that can be used to bridge the relevant length scales from nanometers to millimeters are being developed. The paper focuses on the discussion of newly developed methodologies in these areas and their application to understanding damage processes in aluminum and its alloys.

Modeling and Characterization of Near-Crack-Tip Plasticity from Micro- to Nano-Scales

NASA Technical Reports Server (NTRS)

Glaessgen, Edward H.; Saether, Erik; Hochhalter, Jacob; Smith, Stephen W.; Ransom, Jonathan B.; Yamakov, Vesselin; Gupta, Vipul

2011-01-01

Methodologies for understanding the plastic deformation mechanisms related 10 crack propagation at the nano, meso- and micro-length scales are being developed. These efforts include the development and application of several computational methods including atomistic simulation, discrete dislocation plasticity, strain gradient plasticity and crystal plasticity; and experimental methods including electron backscattered diffraction and video image correlation. Additionally, methodologies for multi-scale modeling and characterization that can be used to bridge the relevant length scales from nanometers to millimeters are being developed. The paper focuses on the discussion of newly developed methodologies in these areas and their application to understanding damage processes in aluminum and its alloys.

Large-scale phase separation with nano-twin domains in manganite spinel (Co,Fe,Mn){sub 3}O{sub 4}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Horibe, Y., E-mail: horibe@post.matsc.kyutech.ac.jp; Takeyama, S.; Mori, S.

The effect of Mn concentration on the formation of nano-domain structures in the spinel oxide (Co,Fe,Mn){sub 3}O{sub 4} was investigated by electron diffraction, bright-, and dark-field imaging technique with transmission electron microscopy. Large scale phase separation with nano-twin domains was observed in Co{sub 0.6}Fe{sub 1.0}Mn{sub 1.4}O{sub 4}, in contrast to the highly aligned checkerboard nano-domains in Co{sub 0.6}Fe{sub 0.9}Mn{sub 1.5}O{sub 4}. Diffusion of the Mn{sup 3+} ions with the Jahn-Teller distortions is suggested to play an important role in the formation of checkerboard nano-domain structure.

Direct Simulations of Coupled Transport and Reaction on Nano-Scale X-Ray Computed Tomography Images of Platinum Group Metal-Free Catalyst Cathodes

DOE PAGES

Ogawa, S.; Komini Babu, S.; Chung, H. T.; ...

2016-08-22

The nano/micro-scale geometry of polymer electrolyte fuel cell (PEFC) catalyst layers critically affects cell performance. The small length scales and complex structure of these composite layers make it challenging to analyze cell performance and physics at the particle scale by experiment. We present a computational method to simulate transport and chemical reaction phenomena at the pore/particle-scale and apply it to a PEFC cathode with platinum group metal free (PGM-free) catalyst. Here, we numerically solve the governing equations for the physics with heterogeneous oxygen diffusion coefficient and proton conductivity evaluated using the actual electrode structure and ionomer distribution obtained using nano-scalemore » resolution X-ray computed tomography (nano-CT). Using this approach, the oxygen concentration and electrolyte potential distributions imposed by the oxygen reduction reaction are solved and the impact of the catalyst layer structure on performance is evaluated.« less

Direct Simulations of Coupled Transport and Reaction on Nano-Scale X-Ray Computed Tomography Images of Platinum Group Metal-Free Catalyst Cathodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ogawa, S.; Komini Babu, S.; Chung, H. T.

The nano/micro-scale geometry of polymer electrolyte fuel cell (PEFC) catalyst layers critically affects cell performance. The small length scales and complex structure of these composite layers make it challenging to analyze cell performance and physics at the particle scale by experiment. We present a computational method to simulate transport and chemical reaction phenomena at the pore/particle-scale and apply it to a PEFC cathode with platinum group metal free (PGM-free) catalyst. Here, we numerically solve the governing equations for the physics with heterogeneous oxygen diffusion coefficient and proton conductivity evaluated using the actual electrode structure and ionomer distribution obtained using nano-scalemore » resolution X-ray computed tomography (nano-CT). Using this approach, the oxygen concentration and electrolyte potential distributions imposed by the oxygen reduction reaction are solved and the impact of the catalyst layer structure on performance is evaluated.« less

Nano-Scale Characterization of Al-Mg Nanocrystalline Alloys

NASA Astrophysics Data System (ADS)

Harvey, Evan; Ladani, Leila

Materials with nano-scale microstructure have become increasingly popular due to their benefit of substantially increased strengths. The increase in strength as a result of decreasing grain size is defined by the Hall-Petch equation. With increased interest in miniaturization of components, methods of mechanical characterization of small volumes of material are necessary because traditional means such as tensile testing becomes increasingly difficult with such small test specimens. This study seeks to characterize elastic-plastic properties of nanocrystalline Al-5083 through nanoindentation and related data analysis techniques. By using nanoindentation, accurate predictions of the elastic modulus and hardness of the alloy were attained. Also, the employed data analysis model provided reasonable estimates of the plastic properties (strain-hardening exponent and yield stress) lending credibility to this procedure as an accurate, full mechanical characterization method.

Reduced wear of enamel with novel fine and nano-scale leucite glass-ceramics.

PubMed

Theocharopoulos, Antonios; Chen, Xiaohui; Hill, Robert; Cattell, Michael J

2013-06-01

Leucite glass-ceramics used to produce all-ceramic restorations can suffer from brittle fracture and wear the opposing teeth. High strength and fine crystal sized leucite glass-ceramics have recently been reported. The objective of this study is to investigate whether fine and nano-scale leucite glass-ceramics with minimal matrix microcracking are associated with a reduction in in vitro tooth wear. Human molar cusps (n=12) were wear tested using a Bionix-858 testing machine (300,000 simulated masticatory cycles) against experimental fine crystal sized (FS), nano-scale crystal sized (NS) leucite glass-ceramics and a commercial leucite glass-ceramic (Ceramco-3, Dentsply, USA). Wear was imaged using Secondary Electron Imaging (SEI) and quantified using white-light profilometry. Both experimental groups were found to produce significantly (p<0.05) less volume and mean-height tooth loss compared to Ceramco-3. The NS group had significantly (p<0.05) less tooth mean-height loss and less combined (tooth and ceramic) loss than the FS group. Increased waviness and damage was observed on the wear surfaces of the Ceramco-3 glass-ceramic disc/tooth group in comparison to the experimental groups. This was also indicated by higher surface roughness values for the Ceramco-3 glass-ceramic disc/tooth group. Fine and nano-sized leucite glass-ceramics produced a reduction in in vitro tooth wear. The high strength low wear materials of this study may help address the many problems associated with tooth enamel wear and restoration failure. Copyright © 2013 Elsevier Ltd. All rights reserved.

Nano-Scale Sample Acquisition Systems for Small Class Exploration Spacecraft

NASA Astrophysics Data System (ADS)

Paulsen, G.

2015-12-01

The paradigm for space exploration is changing. Large and expensive missions are very rare and the space community is turning to smaller, lighter, and less expensive missions that could still perform great exploration. These missions are also within reach of commercial companies such as the Google Lunar X Prize teams that develop small scale lunar missions. Recent commercial endeavors such as "Planet Labs inc." and Sky Box Imaging, inc. show that there are new benefits and business models associated with miniaturization of space hardware. The Nano-Scale Sample Acquisition System includes NanoDrill for capture of small rock cores and PlanetVac for capture of surface regolith. These two systems are part of the ongoing effort to develop "Micro Sampling" systems for deployment by the small spacecraft with limited payload capacities. The ideal applications include prospecting missions to the Moon and Asteroids. The MicroDrill is a rotary-percussive coring drill that captures cores 7 mm in diameter and up to 2 cm long. The drill weighs less than 1 kg and can capture a core from a 40 MPa strength rock within a few minutes, with less than 10 Watt power and less than 10 Newton of preload. The PlanetVac is a pneumatic based regolith acquisition system that can capture surface sample in touch-and-go maneuver. These sampling systems were integrated within the footpads of commercial quadcopter for testing. As such, they could also be used by geologists on Earth to explore difficult to get to locations.

Role of membrane contact sites in protein import into mitochondria

PubMed Central

Horvath, Susanne E; Rampelt, Heike; Oeljeklaus, Silke; Warscheid, Bettina; van der Laan, Martin; Pfanner, Nikolaus

2015-01-01

Mitochondria import more than 1,000 different proteins from the cytosol. The proteins are synthesized as precursors on cytosolic ribosomes and are translocated by protein transport machineries of the mitochondrial membranes. Five main pathways for protein import into mitochondria have been identified. Most pathways use the translocase of the outer mitochondrial membrane (TOM) as the entry gate into mitochondria. Depending on specific signals contained in the precursors, the proteins are subsequently transferred to different intramitochondrial translocases. In this article, we discuss the connection between protein import and mitochondrial membrane architecture. Mitochondria possess two membranes. It is a long-standing question how contact sites between outer and inner membranes are formed and which role the contact sites play in the translocation of precursor proteins. A major translocation contact site is formed between the TOM complex and the presequence translocase of the inner membrane (TIM23 complex), promoting transfer of presequence-carrying preproteins to the mitochondrial inner membrane and matrix. Recent findings led to the identification of contact sites that involve the mitochondrial contact site and cristae organizing system (MICOS) of the inner membrane. MICOS plays a dual role. It is crucial for maintaining the inner membrane cristae architecture and forms contacts sites to the outer membrane that promote translocation of precursor proteins into the intermembrane space and outer membrane of mitochondria. The view is emerging that the mitochondrial protein translocases do not function as independent units, but are embedded in a network of interactions with machineries that control mitochondrial activity and architecture. PMID:25514890

Advanced Ceramics from Preceramic Polymers Modified at the Nano-Scale: A Review.

PubMed

Bernardo, Enrico; Fiocco, Laura; Parcianello, Giulio; Storti, Enrico; Colombo, Paolo

2014-03-06

Preceramic polymers, i.e. , polymers that are converted into ceramics upon heat treatment, have been successfully used for almost 40 years to give advanced ceramics, especially belonging to the ternary SiCO and SiCN systems or to the quaternary SiBCN system. One of their main advantages is the possibility of combining the shaping and synthesis of ceramics: components can be shaped at the precursor stage by conventional plastic-forming techniques, such as spinning, blowing, injection molding, warm pressing and resin transfer molding, and then converted into ceramics by treatments typically above 800 °C. The extension of the approach to a wider range of ceramic compositions and applications, both structural and thermo-structural (refractory components, thermal barrier coatings) or functional (bioactive ceramics, luminescent materials), mainly relies on modifications of the polymers at the nano-scale, i.e. , on the introduction of nano-sized fillers and/or chemical additives, leading to nano-structured ceramic components upon thermal conversion. Fillers and additives may react with the main ceramic residue of the polymer, leading to ceramics of significant engineering interest (such as silicates and SiAlONs), or cause the formation of secondary phases, significantly affecting the functionalities of the polymer-derived matrix.

Advanced Ceramics from Preceramic Polymers Modified at the Nano-Scale: A Review

PubMed Central

Bernardo, Enrico; Fiocco, Laura; Parcianello, Giulio; Storti, Enrico; Colombo, Paolo

2014-01-01

Preceramic polymers, i.e., polymers that are converted into ceramics upon heat treatment, have been successfully used for almost 40 years to give advanced ceramics, especially belonging to the ternary SiCO and SiCN systems or to the quaternary SiBCN system. One of their main advantages is the possibility of combining the shaping and synthesis of ceramics: components can be shaped at the precursor stage by conventional plastic-forming techniques, such as spinning, blowing, injection molding, warm pressing and resin transfer molding, and then converted into ceramics by treatments typically above 800 °C. The extension of the approach to a wider range of ceramic compositions and applications, both structural and thermo-structural (refractory components, thermal barrier coatings) or functional (bioactive ceramics, luminescent materials), mainly relies on modifications of the polymers at the nano-scale, i.e., on the introduction of nano-sized fillers and/or chemical additives, leading to nano-structured ceramic components upon thermal conversion. Fillers and additives may react with the main ceramic residue of the polymer, leading to ceramics of significant engineering interest (such as silicates and SiAlONs), or cause the formation of secondary phases, significantly affecting the functionalities of the polymer-derived matrix. PMID:28788548

Three-dimensional micro/nano-scale structure fabricated by combination of non-volatile polymerizable RTIL and FIB irradiation

PubMed Central

Kuwabata, Susumu; Minamimoto, Hiro; Inoue, Kosuke; Imanishi, Akihito; Hosoya, Ken; Uyama, Hiroshi; Torimoto, Tsukasa; Tsuda, Tetsuya; Seki, Shu

2014-01-01

Room-temperature ionic liquid (RTIL) has been widely investigated as a nonvolatile solvent as well as a unique liquid material because of its interesting features, e.g., negligible vapor pressure and high thermal stability. Here we report that a non-volatile polymerizable RTIL is a useful starting material for the fabrication of micro/nano-scale polymer structures with a focused-ion-beam (FIB) system operated under high-vacuum condition. Gallium-ion beam irradiation to the polymerizable 1-allyl-3-ethylimidazolium bis((trifluoromethane)sulfonyl)amide RTIL layer spread on a Si wafer induced a polymerization reaction without difficulty. What is interesting to note is that we have succeeded in provoking the polymerization reaction anywhere on the Si wafer substrate by using FIB irradiation with a raster scanning mode. By this finding, two- and three-dimensional micro/nano-scale polymer structure fabrications were possible at the resolution of 500,000 dpi. Even intricate three-dimensional micro/nano-figures with overhang and hollow moieties could be constructed at the resolution of approximately 100 nm. PMID:24430465

Titanium bone implants with superimposed micro/nano-scale porosity and antibacterial capability

NASA Astrophysics Data System (ADS)

Necula, B. S.; Apachitei, I.; Fratila-Apachitei, L. E.; van Langelaan, E. J.; Duszczyk, J.

2013-05-01

This study aimed at producing a multifunctional layer with micro/nano-interconnected porosity and antibacterial capability on a rough macro-porous plasma sprayed titanium surface using the plasma electrolytic oxidation process. The layers were electrochemically formed in electrolytes based on calcium acetate and calcium glycerophosphate salts bearing dispersed Ag nanoparticles. They were characterized with respect to surface morphology and chemical composition using a scanning electron microscope equipped with the energy dispersive spectroscopy and back scattering detectors. Scanning electron microscopy images showed the formation of a micro/nano-scale porous layer, comprised of TiO2 bearing Ca and P species and Ag nanoparticles, following accurately the surface topography of the plasma sprayed titanium coating. The Ca/P atomic ratio was found to be close to that of bone apatite. Ag nanoparticles were incorporated on both on top and inside the porous structure of the TiO2 layer.

Optimizing Cr(VI) and Tc(VII) remediation through nano-scale biomineral engineering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cutting, R. S.; Coker, V. S.; Telling, N. D.

2009-09-09

To optimize the production of biomagnetite for the bioremediation of metal oxyanion contaminated waters, the reduction of aqueous Cr(VI) to Cr(III) by two biogenic magnetites and a synthetic magnetite was evaluated under batch and continuous flow conditions. Results indicate that nano-scale biogenic magnetite produced by incubating synthetic schwertmannite powder in cell suspensions of Geobacter sulfurreducens is more efficient at reducing Cr(VI) than either biogenic nano-magnetite produced from a suspension of ferrihydrite 'gel' or synthetic nano-scale Fe{sub 3}O{sub 4} powder. Although X-ray Photoelectron Spectroscopy (XPS) measurements obtained from post-exposure magnetite samples reveal that both Cr(III) and Cr(VI) are associated with nanoparticlemore » surfaces, X-ray Magnetic Circular Dichroism (XMCD) studies indicate that some Cr(III) has replaced octahedrally coordinated Fe in the lattice of the magnetite. Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) measurements of total aqueous Cr in the associated solution phase indicated that, although the majority of Cr(III) was incorporated within or adsorbed to the magnetite samples, a proportion ({approx}10-15 %) was released back into solution. Studies of Tc(VII) uptake by magnetites produced via the different synthesis routes also revealed significant differences between them as regards effectiveness for remediation. In addition, column studies using a {gamma}-camera to obtain real time images of a {sup 99m}Tc(VII) radiotracer were performed to visualize directly the relative performances of the magnetite sorbents against ultra-trace concentrations of metal oxyanion contaminants. Again, the magnetite produced from schwertmannite proved capable of retaining more ({approx}20%) {sup 99m}Tc(VII) than the magnetite produced from ferrihydrite, confirming that biomagnetite production for efficient environmental remediation can be fine-tuned through careful selection of the initial Fe(III) mineral

The fabrication and hydrophobic property of micro-nano patterned surface on magnesium alloy using combined sparking sculpture and etching route

NASA Astrophysics Data System (ADS)

Wu, Yunfeng; Wang, Yaming; Liu, Hao; Liu, Yan; Guo, Lixin; Jia, Dechang; Ouyang, Jiahu; Zhou, Yu

2016-12-01

Magnesium alloy with micro-nano structure roughness surface, can serve as the loading reservoirs of medicine capsule and industrial lubricating oil, or mimic 'lotus leaf' hydrophobic surface, having the potential applications in medical implants, automobile, aerospace and electronic products, etc. Herein, we propose a novel strategy to design a micro-nano structure roughness surface on magnesium alloy using combined microarc sparking sculpture and etching in CrO3 aqueous solution. A hydrophobic surface (as an applied example) was further fabricated by chemical decorating on the obtained patterned magnesium alloy surface to enhance the corrosion resistance. The results show that the combined micro-nano structure of 7-9 μm diameter big pores insetting with nano-scale fine pores was duplicated after etched the sparking sculptured 'over growth' oxide regions towards the magnesium substrate. The micro-nano structure surface was chemically decorated using AgNO3 and stearic acid, which enables the contact angle increased from 60° to 146.8°. The increasing contact angle is mainly attributed to the micro-nano structure and the chemical composition. The hydrophobic surface of magnesium alloy improved the corrosion potential from -1.521 V of the bare magnesium to -1.274 V. Generally, the sparking sculpture and then etching route demonstrates a low-cost, high-efficacy method to fabricate a micro-nano structure hydrophobic surface on magnesium alloy. Furthermore, our research on the creating of micro-nano structure roughness surface and the hydrophobic treatment can be easily extended to the other metal materials.

Multi-scale analysis of the effect of nano-filler particle diameter on the physical properties of CAD/CAM composite resin blocks.

PubMed

Yamaguchi, Satoshi; Inoue, Sayuri; Sakai, Takahiko; Abe, Tomohiro; Kitagawa, Haruaki; Imazato, Satoshi

2017-05-01

The objective of this study was to assess the effect of silica nano-filler particle diameters in a computer-aided design/manufacturing (CAD/CAM) composite resin (CR) block on physical properties at the multi-scale in silico. CAD/CAM CR blocks were modeled, consisting of silica nano-filler particles (20, 40, 60, 80, and 100 nm) and matrix (Bis-GMA/TEGDMA), with filler volume contents of 55.161%. Calculation of Young's moduli and Poisson's ratios for the block at macro-scale were analyzed by homogenization. Macro-scale CAD/CAM CR blocks (3 × 3 × 3 mm) were modeled and compressive strengths were defined when the fracture loads exceeded 6075 N. MPS values of the nano-scale models were compared by localization analysis. As the filler size decreased, Young's moduli and compressive strength increased, while Poisson's ratios and MPS decreased. All parameters were significantly correlated with the diameters of the filler particles (Pearson's correlation test, r = -0.949, 0.943, -0.951, 0.976, p < 0.05). The in silico multi-scale model established in this study demonstrates that the Young's moduli, Poisson's ratios, and compressive strengths of CAD/CAM CR blocks can be enhanced by loading silica nanofiller particles of smaller diameter. CAD/CAM CR blocks by using smaller silica nano-filler particles have a potential to increase fracture resistance.

Correlation between surface properties and wettability of multi-scale structured biocompatible surfaces

NASA Astrophysics Data System (ADS)

Gorodzha, S. N.; Surmeneva, M. A.; Prymak, O.; Wittmar, A.; Ulbricht, M.; Epple, M.; Teresov, A.; Koval, N.; Surmenev, R. A.

2015-11-01

The influence of surface properties of radio-frequency (RF) magnetron deposited hydroxyapatite (HA) and Si-containing HA coatings on wettability was studied. The composition and morphology of the coatings fabricated on titanium (Ti) were characterized using atomic force microscopy (AFM) and X-ray diffraction (XRD). The surface wettability was studied using contact angle analysis. Different geometric parameters of acid-etched (AE) and pulse electron beam (PEB)-treated Ti substrates and silicate content in the HA films resulted in the different morphology of the coatings at micro- and nano- length scales. Water contact angles for the HA coated Ti samples were evaluated as a combined effect of micro roughness of the substrate and nano-roughness of the HA films resulting in higher water contact angles compared with acid-etched (AE) or pulse electron beam (PEB) treated Ti substrates.

Micro- and nano-scale characterization to study the thermal degradation of cement-based materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lim, Seungmin, E-mail: lim76@illinois.edu; Mondal, Paramita

2014-06-01

The degradation of hydration products of cement is known to cause changes in the micro- and nano-structure, which ultimately drive thermo-mechanical degradation of cement-based composite materials at elevated temperatures. However, a detailed characterization of these changes is still incomplete. This paper presents results of an extensive experimental study carried out to investigate micro- and nano-structural changes that occur due to exposure of cement paste to high temperatures. Following heat treatment of cement paste up to 1000 °C, damage states were studied by compressive strength test, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) atomic force microscopy (AFM) and AFM image analysis.more » Using experimental results and research from existing literature, new degradation processes that drive the loss of mechanical properties of cement paste are proposed. The development of micro-cracks at the interface between unhydrated cement particles and paste matrix, a change in C–S–H nano-structure and shrinkage of C–S–H, are considered as important factors that cause the thermal degradation of cement paste. - Highlights: • The thermal degradation of hydration products of cement is characterized at micro- and nano-scale using scanning electron microscopy (SEM) and atomic force microscopy (AFM). • The interface between unhydrated cement particles and the paste matrix is considered the origin of micro-cracks. • When cement paste is exposed to temperatures above 300 ºC, the nano-structure of C-S-H becomes a more loosely packed globular structure, which could be indicative of C-S-H shrinkage.« less

[Preparation of nano-nacre artificial bone].

PubMed

Chen, Jian-ting; Tang, Yong-zhi; Zhang, Jian-gang; Wang, Jian-jun; Xiao, Ying

2008-12-01

To assess the improvements in the properties of nano-nacre artificial bone prepared on the basis of nacre/polylactide acid composite artificial bone and its potential for clinical use. The compound of nano-scale nacre powder and poly-D, L-lactide acid (PDLLA) was used to prepare the cylindrical hollow artificial bone, whose properties including raw material powder scale, pore size, porosity and biomechanical characteristics were compared with another artificial bone made of micron-scale nacre powder and PDLLA. Scanning electron microscope showed that the average particle size of the nano-nacre powder was 50.4-/+12.4 nm, and the average pore size of the artificial bone prepared using nano-nacre powder was 215.7-/+77.5 microm, as compared with the particle size of the micron-scale nacre powder of 5.0-/+3.0 microm and the pore size of the resultant artificial bone of 205.1-/+72.0 microm. The porosities of nano-nacre artificial bone and the micron-nacre artificial bone were (65.4-/+2.9)% and (53.4-/+2.2)%, respectively, and the two artificial bones had comparable compressive strength and Young's modulus, but the flexural strength of the nano-nacre artificial bone was lower than that of the micro-nacre artificial bone. The nano-nacre artificial bone allows better biodegradability and possesses appropriate pore size, porosity and biomechanical properties for use as a promising material in bone tissue engineering.

A new multiscale model to describe a modified Hall-Petch relation at different scales for nano and micro materials

NASA Astrophysics Data System (ADS)

Fadhil, Sadeem Abbas; Alrawi, Aoday Hashim; Azeez, Jazeel H.; Hassan, Mohsen A.

2018-04-01

In the present work, a multiscale model is presented and used to modify the Hall-Petch relation for different scales from nano to micro. The modified Hall-Petch relation is derived from a multiscale equation that determines the cohesive energy between the atoms and their neighboring grains. This brings with it a new term that was originally ignored even in the atomistic models. The new term makes it easy to combine all other effects to derive one modified equation for the Hall-Petch relation that works for all scales together, without the need to divide the scales into two scales, each scale with a different equation, as it is usually done in other works. Due to that, applying the new relation does not require a previous knowledge of the grain size distribution. This makes the new derived relation more consistent and easier to be applied for all scales. The new relation is used to fit the data for Copper and Nickel and it is applied well for the whole range of grain sizes from nano to micro scales.

SCIL nanoimprint solutions: high-volume soft NIL for wafer scale sub-10nm resolution

NASA Astrophysics Data System (ADS)

Voorkamp, R.; Verschuuren, M. A.; van Brakel, R.

2016-10-01

Nano-patterning materials and surfaces can add unique functionalities and properties which cannot be obtained in bulk or micro-structured materials. Examples range from hetro-epitaxy of semiconductor nano-wires to guiding cell expression and growth on medical implants. [1] Due to the cost and throughput requirements conventional nano-patterning techniques such as deep UV lithography (cost and flat substrate demands) and electron-beam lithography (cost, throughput) are not an option. Self-assembly techniques are being considered for IC manufacturing, but require nano-sized guiding patterns, which have to be fabricated in any case.[2] Additionally, the self-assembly process is highly sensitive to the environment and layer thickness, which is difficult to control on non-flat surfaces such as PV silicon wafers or III/V substrates. Laser interference lithography can achieve wafer scale periodic patterns, but is limited by the throughput due to intensity of the laser at the pinhole and only regular patterns are possible where the pattern fill fraction cannot be chosen freely due to the interference condition.[3] Nanoimprint lithography (NIL) is a promising technology for the cost effective fabrication of sub-micron and nano-patterns on large areas. The challenges for NIL are related to the technique being a contact method where a stamp which holds the patterns is required to be brought into intimate contact with the surface of the product. In NIL a strong distinction is made between the type of stamp used, either rigid or soft. Rigid stamps are made from patterned silicon, silica or plastic foils and are capable of sub-10nm resolution and wafer scale patterning. All these materials behave similar at the micro- to nm scale and require high pressures (5 - 50 Bar) to enable conformal contact to be made on wafer scales. Real world conditions such as substrate bow and particle contaminants complicate the use of rigid stamps for wafer scale areas, reducing stamp lifetime and

Nano-soldering of magnetically aligned three-dimensional nanowire networks.

PubMed

Gao, Fan; Gu, Zhiyong

2010-03-19

It is extremely challenging to fabricate 3D integrated nanostructures and hybrid nanoelectronic devices. In this paper, we report a simple and efficient method to simultaneously assemble and solder nanowires into ordered 3D and electrically conductive nanowire networks. Nano-solders such as tin were fabricated onto both ends of multi-segmented nanowires by a template-assisted electrodeposition method. These nanowires were then self-assembled and soldered into large-scale 3D network structures by magnetic field assisted assembly in a liquid medium with a high boiling point. The formation of junctions/interconnects between the nanowires and the scale of the assembly were dependent on the solder reflow temperature and the strength of the magnetic field. The size of the assembled nanowire networks ranged from tens of microns to millimeters. The electrical characteristics of the 3D nanowire networks were measured by regular current-voltage (I-V) measurements using a probe station with micropositioners. Nano-solders, when combined with assembling techniques, can be used to efficiently connect and join nanowires with low contact resistance, which are very well suited for sensor integration as well as nanoelectronic device fabrication.

Characteristic Behavior and Scaling Studies of Self Organized InP Nano-dots formed via keV and MeV irradiations

NASA Astrophysics Data System (ADS)

Paramanik, Dipak; Varma, Shikha

2008-04-01

The controlled formation of nano-dots, using ion beams as tool, has become important as it offers a unique method to generate non-equilibrium phases with novel physical properties and structures with nano-dimensions. We have investigated the creation of self assembled nano- dots on InP(111) surfaces after 3 keV as well as 1.5 MeV ion beams at a large range of fluences. We have studied the Scaling exponents of the evolved surfaces by utilizing the technique of Scanning Probe Microscopy (SPM). At keV energies ripening of the nano-dots is seen below a critical time whereas an inverse ripening is observed for longer durations. At the critical time square shaped array of nano --dots are observed. The dots are characterized by narrow height and size distributions. Nano dots have also been observed at MeV ion irradiations. Their size distribution though broad at lowest fluence decreases for larger fluences.

Performance assessment and optimization of an irreversible nano-scale Stirling engine cycle operating with Maxwell-Boltzmann gas

NASA Astrophysics Data System (ADS)

Ahmadi, Mohammad H.; Ahmadi, Mohammad-Ali; Pourfayaz, Fathollah

2015-09-01

Developing new technologies like nano-technology improves the performance of the energy industries. Consequently, emerging new groups of thermal cycles in nano-scale can revolutionize the energy systems' future. This paper presents a thermo-dynamical study of a nano-scale irreversible Stirling engine cycle with the aim of optimizing the performance of the Stirling engine cycle. In the Stirling engine cycle the working fluid is an Ideal Maxwell-Boltzmann gas. Moreover, two different strategies are proposed for a multi-objective optimization issue, and the outcomes of each strategy are evaluated separately. The first strategy is proposed to maximize the ecological coefficient of performance (ECOP), the dimensionless ecological function (ecf) and the dimensionless thermo-economic objective function ( F . Furthermore, the second strategy is suggested to maximize the thermal efficiency ( η), the dimensionless ecological function (ecf) and the dimensionless thermo-economic objective function ( F). All the strategies in the present work are executed via a multi-objective evolutionary algorithms based on NSGA∥ method. Finally, to achieve the final answer in each strategy, three well-known decision makers are executed. Lastly, deviations of the outcomes gained in each strategy and each decision maker are evaluated separately.

A non-contact measurement technique at the micro scale

NASA Astrophysics Data System (ADS)

Ghosh, Santaneel

During their production and normal use, electronic packages experience large temperature excursions, leading to high thermo-mechanical stress gradients that cause fatigue failure of the solder joints. In order to prevent premature failure and prolong the fatigue life of solder joints, there is a pressing need for the characterization of the solder, especially lead-free solder, at the micro-level (joint size). The characterization and modeling of solder behavior at the appropriate scale is a major issue. However, direct measurement techniques are not applicable to characterize the deformation response of solder joints because of their micro scale dimensions. Therefore, a non-contact measurement technique utilizing a Scanning Electron Microscope (SEM) in conjunction with Digital Image Correlation (DIC) has been developed. Validation was achieved by performing a four-point bending test in both an in-house optical system with DIC and inside the SEM. This non-contact measurement technique was then used to extract the stress-strain response of the solder. Mechanical tests were performed on solder joints that were created using the same type of solder balls used in the electronic industry and were representative of normal joint scales. The SEM-DIC technique has been proven to be applicable for the determining the stress-strain response of solder material at the micro-scale. This study resulted in a validated material characterization technique specifically designed for micro-scale material response. One of the main contributions of this study is that the method is a lot simpler and cheaper, yet highly effective, compared to the previous methods. This technique is also readily applicable to the measurement of the stress-strain response of any micro-scale specimen, such as other metals, polymers, etc. Also, the measured displacement field by obtained by DIC can be used as the base for calculating the strain field on the surface of a specimen.

Incineration of a Commercial Coating with Nano CeO2

NASA Astrophysics Data System (ADS)

Le Bihan, Olivier; Ounoughene, Ghania; Meunier, Laurent; Debray, Bruno; Aguerre-Chariol, Olivier

2017-06-01

The potential environmental risk arising from the incineration of waste containing nanomaterials is a new field which deserves further attention. Some recent studies have begun to focus on this topic but the data are incomplete. In addition, there is a need to consider real life waste. The present study gives some insight into the fate and behavior of a commercial coating containing a commercial additive (7% w/w) based on nano-CeO2 (aggregates of 10 to 40 nm, with elemental particles of 2-3 nm). The tests have been conducted with a system developed in the frame of the NanoFlueGas project. The test protocol was designed to respect the regulatory criteria of a good combustion in incineration plants (temperature around 850°C, highly ventilated combustion, at least 2 s residence time for the combustion gas in a post-combustion chamber at 850°C, and high oxygen/fuel contact). Time tracking by electric low pressure impaction (ELPI) shows that the incineration produces aerosol with number concentration dominated by sub-100 nm particles. Cerium is observed by TEM and EDS analysis but as a minor compound of a sub-group of particles. No nanoCeO2 particles have been observed in the aerosol. ICP-MS analysis indicates that the residual material consists mainly of CeO2 (60% of the mass). Observation by TEM establishes that this material is in the form of aggregates with individual particle of 40-200 nm and suggests that sintering occurred during incineration. As a conclusion, the lab scale incineration study led mainly to the release of nano-CeO2 in the residual material, as the major component. Its size distribution is different than the one of the nano-CeO2 observed in the initial sample before incineration. Additional research is needed to improve the understanding of nanoCeO2 behavior, and to integrate experiments at lab and real scale.

Emulsified Zero-Valent Nano-Scale Iron Treatment of Chlorinated Solvent DNAPL Source Areas

DTIC Science & Technology

2010-04-01

The EZVI is composed of food-grade surfactant, biodegradable oil , water, and ZVI particles (either nano- or micro-scale iron), which form...emulsion particles (Figure 2-1). Each emulsion particle or droplet contains ZVI particles in water surrounded by an oil -liquid membrane. Since the...exterior oil membrane of the emulsion droplet has hydrophobic properties similar to that of DNAPL, the droplets are miscible with DNAPL. It is believed

1-dimension nano-material-based flexible device

NASA Astrophysics Data System (ADS)

Yang, Xing; Zhou, Zhaoying; Zheng, Fuzhong

2009-11-01

1D nano-material-based flexible devices has attracted considerable attention owing to the growing need of the high-sensitivity flexible sensor, portable consumer electronics etc.. In this paper, the 1D nano-materials-based flexible device on polyimide substrate was proposed. The bottom-up and top-down combined process were used for constructing the ZnO nanowire and the CNT-based flexible devices. Their electrical characteristics were also investigated. The measurement results demonstrate that the flexible device covered with a layer of Al2O3 has good ohm electrical contact behavior between the nano-material and micro-electrodes. The proposed 1D nano-material-based flexible device shows the application potential in the sensing fields.

Nano Scale Mechanical Analysis of Biomaterials Using Atomic Force Microscopy

NASA Astrophysics Data System (ADS)

Dutta, Diganta

The atomic force microscope (AFM) is a probe-based microscope that uses nanoscale and structural imaging where high resolution is desired. AFM has also been used in mechanical, electrical, and thermal engineering applications. This unique technique provides vital local material properties like the modulus of elasticity, hardness, surface potential, Hamaker constant, and the surface charge density from force versus displacement curve. Therefore, AFM was used to measure both the diameter and mechanical properties of the collagen nanostraws in human costal cartilage. Human costal cartilage forms a bridge between the sternum and bony ribs. The chest wall of some humans is deformed due to defective costal cartilage. However, costal cartilage is less studied compared to load bearing cartilage. Results show that there is a difference between chemical fixation and non-chemical fixation treatments. Our findings imply that the patients' chest wall is mechanically weak and protein deposition is abnormal. This may impact the nanostraws' ability to facilitate fluid flow between the ribs and the sternum. At present, AFM is the only tool for imaging cells' ultra-structure at the nanometer scale because cells are not homogeneous. The first layer of the cell is called the cell membrane, and the layer under it is made of the cytoskeleton. Cancerous cells are different from normal cells in term of cell growth, mechanical properties, and ultra-structure. Here, force is measured with very high sensitivity and this is accomplished with highly sensitive probes such as a nano-probe. We performed experiments to determine ultra-structural differences that emerge when such cancerous cells are subject to treatments such as with drugs and electric pulses. Jurkat cells are cancerous cells. These cells were pulsed at different conditions. Pulsed and non-pulsed Jurkat cell ultra-structures were investigated at the nano meter scale using AFM. Jurkat cell mechanical properties were measured under

Meissner effect measurement of single indium particle using a customized on-chip nano-scale superconducting quantum interference device system

NASA Astrophysics Data System (ADS)

Wu, Long; Chen, Lei; Wang, Hao; Liu, Xiaoyu; Wang, Zhen

2017-04-01

As many emergent phenomena of superconductivity appear on a smaller scale and at lower dimension, commercial magnetic property measurement systems (MPMSs) no longer provide the sensitivity necessary to study the Meissner effect of small superconductors. The nano-scale superconducting quantum interference device (nano-SQUID) is considered one of the most sensitive magnetic sensors for the magnetic characterization of mesoscopic or microscopic samples. Here, we develop a customized on-chip nano-SQUID measurement system based on a pulsed current biasing method. The noise performance of our system is approximately 4.6 × 10-17 emu/Hz1/2, representing an improvement of 9 orders of magnitude compared with that of a commercial MPMS (~10-8 emu/Hz1/2). Furthermore, we demonstrate the measurement of the Meissner effect of a single indium (In) particle (of 47 μm in diameter) using our on-chip nano-SQUID system. The system enables the observation of the prompt superconducting transition of the Meissner effect of a single In particle, thereby providing more accurate characterization of the critical field Hc and temperature Tc. In addition, the retrapping field Hre as a function of temperature T of single In particle shows disparate behavior from that of a large ensemble.

The Hydrophobicity and Adhesion of Heterogeneous Surfaces of Dual Nanometer and Micron Scale Structures

DTIC Science & Technology

2011-04-11

scale post geometry. superhydrophobic , surface modification, adhesion, contact angle, Cassie, Wenzel, PDMS, CYTOP, Teflon AF, roll-off angle U U U U SAR...width > 1, the micro-scale features dominated the wetting state regardless of the nano-scale post geometry., KEYWORDS superhydrophobic , surface... superhydrophobicity can be routinely found in nature. Fo~ example, many plant leaves1.2, bird feathers3, insect wings and insect legs4 take advantage of

Bacterial toxicity comparison between nano- and micro-scaled oxide particles.

PubMed

Jiang, Wei; Mashayekhi, Hamid; Xing, Baoshan

2009-05-01

Toxicity of nano-scaled aluminum, silicon, titanium and zinc oxides to bacteria (Bacillus subtilis, Escherichia coli and Pseudomonas fluorescens) was examined and compared to that of their respective bulk (micro-scaled) counterparts. All nanoparticles but titanium oxide showed higher toxicity (at 20 mg/L) than their bulk counterparts. Toxicity of released metal ions was differentiated from that of the oxide particles. ZnO was the most toxic among the three nanoparticles, causing 100% mortality to the three tested bacteria. Al(2)O(3) nanoparticles had a mortality rate of 57% to B. subtilis, 36% to E. coli, and 70% to P. fluorescens. SiO(2) nanoparticles killed 40% of B. subtilis, 58% of E. coli, and 70% of P. fluorescens. TEM images showed attachment of nanoparticles to the bacteria, suggesting that the toxicity was affected by bacterial attachment. Bacterial responses to nanoparticles were different from their bulk counterparts; hence nanoparticle toxicity mechanisms need to be studied thoroughly.

A nano-scale mirror-like surface of Ti-6Al-4V attained by chemical mechanical polishing

NASA Astrophysics Data System (ADS)

Chenliang, Liang; Weili, Liu; Shasha, Li; Hui, Kong; Zefang, Zhang; Zhitang, Song

2016-05-01

Metal Ti and its alloys have been widely utilized in the fields of aviation, medical science, and micro-electro-mechanical systems, for its excellent specific strength, resistance to corrosion, and biological compatibility. As the application of Ti moves to the micro or nano scale, however, traditional methods of planarization have shown their short slabs. Thus, we introduce the method of chemical mechanical polishing (CMP) to provide a new way for the nano-scale planarization method of Ti alloys. We obtain a mirror-like surface, whose flatness is of nano-scale, via the CMP method. We test the basic mechanical behavior of Ti-6Al-4V (Ti64) in the CMP process, and optimize the composition of CMP slurry. Furthermore, the possible reactions that may take place in the CMP process have been studied by electrochemical methods combined with x-ray photoelectron spectroscopy (XPS). An equivalent circuit has been built to interpret the dynamic of oxidation. Finally, a model has been established to explain the synergy of chemical and mechanical effects in the CMP of Ti-6Al-4V. Project supported by the National Major Scientific and Technological Special Project during the Twelfth Five-year Plan Period of China (Grant No. 2009ZX02030-1), the National Natural Science Foundation of China (Grant No. 51205387), the Support by Science and Technology Commission of Shanghai City, China (Grant No. 11nm0500300), and the Science and Technology Commission of Shanghai City, China (Grant No. 14XD1425300).

Indium-tin-oxide nanowhiskers crystalline silicon photovoltaics combining micro- and nano-scale surface textures

NASA Astrophysics Data System (ADS)

Chang, C. H.; Hsu, M. H.; Chang, W. L.; Sun, W. C.; Yu, Peichen

2011-02-01

In this work, we present a solution that employs combined micro- and nano-scale surface textures to increase light harvesting in the near infrared for crystalline silicon photovoltaics, and discuss the associated antireflection and scattering mechanisms. The combined surface textures are achieved by uniformly depositing a layer of indium-tin-oxide nanowhiskers on passivated, micro-grooved silicon solar cells using electron-beam evaporation. The nanowhiskers facilitate optical transmission in the near-infrared, which is optically equivalent to a stack of two dielectric thin-films with step- and graded- refractive index profiles. The ITO nanowhiskers provide broadband anti-reflective properties (R<5%) in the wavelength range of 350-1100nm. In comparison with conventional Si solar cell, the combined surface texture solar cell shows higher external quantum efficiency (EQE) in the range of 700-1100nm. Moreover, the ITO nano-whisker coating Si solar cell shows a high total efficiency increase of 1.1% (from 16.08% to17.18%). Furthermore, the nano-whiskers also provide strong forward scattering for ultraviolet and visible light, favorable in thin-wafer silicon photovoltaics to increase the optical absorption path.

Sub-diffraction nano manipulation using STED AFM.

PubMed

Chacko, Jenu Varghese; Canale, Claudio; Harke, Benjamin; Diaspro, Alberto

2013-01-01

In the last two decades, nano manipulation has been recognized as a potential tool of scientific interest especially in nanotechnology and nano-robotics. Contemporary optical microscopy (super resolution) techniques have also reached the nanometer scale resolution to visualize this and hence a combination of super resolution aided nano manipulation ineluctably gives a new perspective to the scenario. Here we demonstrate how specificity and rapid determination of structures provided by stimulated emission depletion (STED) microscope can aid another microscopic tool with capability of mechanical manoeuvring, like an atomic force microscope (AFM) to get topological information or to target nano scaled materials. We also give proof of principle on how high-resolution real time visualization can improve nano manipulation capability within a dense sample, and how STED-AFM is an optimal combination for this job. With these evidences, this article points to future precise nano dissections and maybe even to a nano-snooker game with an AFM tip and fluorospheres.

In Vitro Phototoxicity and Hazard Identification of Nano-scale Titanium Dioxide

EPA Science Inventory

Nano-titanium dioxide (nano-Ti02) catalyzes many reactions under UV radiation and is hypothesized to cause phototoxicity. A human-derived line of retinal pigment epithelial cells (ARPE-19) was treated with six different samples of nano-Ti02 and exposed to UVA radiation. The Ti02 ...

The Influence of Fluorination on Nano-Scale Phase Separation and Photovoltaic Performance of Small Molecular/PC71BM Blends

PubMed Central

Lu, Zhen; Liu, Wen; Li, Jingjing; Fang, Tao; Li, Wanning; Zhang, Jicheng; Feng, Feng; Li, Wenhua

2016-01-01

To investigate the fluorination influence on the photovoltaic performance of small molecular based organic solar cells (OSCs), six small molecules based on 2,1,3-benzothiadiazole (BT), and diketopyrrolopyrrole (DPP) as core and fluorinated phenyl (DFP) and triphenyl amine (TPA) as different terminal units (DFP-BT-DFP, DFP-BT-TPA, TPA-BT-TPA, DFP-DPP-DFP, DFP-DPP-TPA, and TPA-DPP-TPA) were synthesized. With one or two fluorinated phenyl as the end group(s), HOMO level of BT and DPP based small molecular donors were gradually decreased, inducing high open circuit voltage for fluorinated phenyl based OSCs. DFP-BT-TPA and DFP-DPP-TPA based blend films both displayed stronger nano-scale aggregation in comparison to TPA-BT-TPA and TPA-DPP-TPA, respectively, which would also lead to higher hole motilities in devices. Ultimately, improved power conversion efficiency (PCE) of 2.17% and 1.22% was acquired for DFP-BT-TPA and DFP-DPP-TPA based devices, respectively. These results demonstrated that the nano-scale aggregation size of small molecules in photovoltaic devices could be significantly enhanced by introducing a fluorine atom at the donor unit of small molecules, which will provide understanding about the relationship of chemical structure and nano-scale phase separation in OSCs. PMID:28335208

Nano- and micro-scale Bi-substituted iron garnet films for photonics and magneto-optic eddy current defectoscopy

NASA Astrophysics Data System (ADS)

Berzhansky, V. N.; Karavainikov, A. V.; Mikhailova, T. V.; Prokopov, A. R.; Shaposhnikov, A. N.; Shumilov, A. G.; Lugovskoy, N. V.; Semuk, E. Yu.; Kharchenko, M. F.; Lukienko, I. M.; Kharchenko, Yu. M.; Belotelov, V. I.

2017-10-01

Synthesis technology of nano-scale Bi-substituted iron garnets films with high magneto-optic activity for photonics and plasmonics applications were proposed. The micro-scale single-crystal garnet films with different types of magnetic anisotropy as a magneto-optic sensors were synthesized. It was shown that easy-axis anisotropy films demonstrated the best results for visualization of redistribution eddy current magnetic field near defects.

Developing an Effective Model for Shale Gas Flow in Nano-scale Pore Clusters based on FIB-SEM Images

NASA Astrophysics Data System (ADS)

Jiang, W. B.; Lin, M.; Yi, Z. X.; Li, H. S.

2016-12-01

Nano-scale pores existed in the form of clusters are the controlling void space in shale gas reservoir. Gas transport in nanopores which has a significant influence on shale gas' recoverability displays multiple transport regimes, including viscous, slippage flow and Knudsen diffusion. In addition, it is also influenced by pore space characteristics. For convenience and efficiency consideration, it is necessary to develop an upscaling model from nano pore to pore cluster scale. Existing models are more like framework functions that provide a format, because the parameters that represent pore space characteristics are underdetermined and may have multiple possibilities. Therefore, it is urgent to make them clear and obtained a model that is closer to reality. FIB-SEM imaging technology is able to acquire three dimensional images with nanometer resolution that nano pores can be visible. Based on the images of two shale samples, we used a high-precision pore network extraction algorithm to generate equivalent pore networks and simulate multiple regime (non-Darcy) flow in it. Several structural parameters can be obtained through pore network modelling. It is found that although the throat-radius distributions are very close, throat flux-radius distributions of different samples can be divided into two categories. The variation of tortuosity with pressure and the overall trend of throat-flux distribution changes with pressure are disclosed. A deeper understanding of shale gas flow in nano-scale pore clusters is obtained. After all, an upscaling model that connects absolute permeability, apparent permeability and other characteristic parameters is proposed, and the best parameter scheme considering throat number-radius distribution and flowing porosity for this model is selected out of three schemes based on pore scale results, and it can avoid multiple-solution problem and is useful in reservoir modelling and experiment result analysis, etc. This work is supported by

Nano Mechanical Machining Using AFM Probe

NASA Astrophysics Data System (ADS)

Mostofa, Md. Golam

Complex miniaturized components with high form accuracy will play key roles in the future development of many products, as they provide portability, disposability, lower material consumption in production, low power consumption during operation, lower sample requirements for testing, and higher heat transfer due to their very high surface-to-volume ratio. Given the high market demand for such micro and nano featured components, different manufacturing methods have been developed for their fabrication. Some of the common technologies in micro/nano fabrication are photolithography, electron beam lithography, X-ray lithography and other semiconductor processing techniques. Although these methods are capable of fabricating micro/nano structures with a resolution of less than a few nanometers, some of the shortcomings associated with these methods, such as high production costs for customized products, limited material choices, necessitate the development of other fabricating techniques. Micro/nano mechanical machining, such an atomic force microscope (AFM) probe based nano fabrication, has, therefore, been used to overcome some the major restrictions of the traditional processes. This technique removes material from the workpiece by engaging micro/nano size cutting tool (i.e. AFM probe) and is applicable on a wider range of materials compared to the photolithographic process. In spite of the unique benefits of nano mechanical machining, there are also some challenges with this technique, since the scale is reduced, such as size effects, burr formations, chip adhesions, fragility of tools and tool wear. Moreover, AFM based machining does not have any rotational movement, which makes fabrication of 3D features more difficult. Thus, vibration-assisted machining is introduced into AFM probe based nano mechanical machining to overcome the limitations associated with the conventional AFM probe based scratching method. Vibration-assisted machining reduced the cutting forces

Non-linear, non-monotonic effect of nano-scale roughness on particle deposition in absence of an energy barrier: Experiments and modeling

PubMed Central

Jin, Chao; Glawdel, Tomasz; Ren, Carolyn L.; Emelko, Monica B.

2015-01-01

Deposition of colloidal- and nano-scale particles on surfaces is critical to numerous natural and engineered environmental, health, and industrial applications ranging from drinking water treatment to semi-conductor manufacturing. Nano-scale surface roughness-induced hydrodynamic impacts on particle deposition were evaluated in the absence of an energy barrier to deposition in a parallel plate system. A non-linear, non-monotonic relationship between deposition surface roughness and particle deposition flux was observed and a critical roughness size associated with minimum deposition flux or “sag effect” was identified. This effect was more significant for nanoparticles (<1 μm) than for colloids and was numerically simulated using a Convective-Diffusion model and experimentally validated. Inclusion of flow field and hydrodynamic retardation effects explained particle deposition profiles better than when only the Derjaguin-Landau-Verwey-Overbeek (DLVO) force was considered. This work provides 1) a first comprehensive framework for describing the hydrodynamic impacts of nano-scale surface roughness on particle deposition by unifying hydrodynamic forces (using the most current approaches for describing flow field profiles and hydrodynamic retardation effects) with appropriately modified expressions for DLVO interaction energies, and gravity forces in one model and 2) a foundation for further describing the impacts of more complicated scales of deposition surface roughness on particle deposition. PMID:26658159

Non-linear, non-monotonic effect of nano-scale roughness on particle deposition in absence of an energy barrier: Experiments and modeling

NASA Astrophysics Data System (ADS)

Jin, Chao; Glawdel, Tomasz; Ren, Carolyn L.; Emelko, Monica B.

2015-12-01

Deposition of colloidal- and nano-scale particles on surfaces is critical to numerous natural and engineered environmental, health, and industrial applications ranging from drinking water treatment to semi-conductor manufacturing. Nano-scale surface roughness-induced hydrodynamic impacts on particle deposition were evaluated in the absence of an energy barrier to deposition in a parallel plate system. A non-linear, non-monotonic relationship between deposition surface roughness and particle deposition flux was observed and a critical roughness size associated with minimum deposition flux or “sag effect” was identified. This effect was more significant for nanoparticles (<1 μm) than for colloids and was numerically simulated using a Convective-Diffusion model and experimentally validated. Inclusion of flow field and hydrodynamic retardation effects explained particle deposition profiles better than when only the Derjaguin-Landau-Verwey-Overbeek (DLVO) force was considered. This work provides 1) a first comprehensive framework for describing the hydrodynamic impacts of nano-scale surface roughness on particle deposition by unifying hydrodynamic forces (using the most current approaches for describing flow field profiles and hydrodynamic retardation effects) with appropriately modified expressions for DLVO interaction energies, and gravity forces in one model and 2) a foundation for further describing the impacts of more complicated scales of deposition surface roughness on particle deposition.

A system approach for reducing the environmental impact of manufacturing and sustainability improvement of nano-scale manufacturing

NASA Astrophysics Data System (ADS)

Yuan, Yingchun

This dissertation develops an effective and economical system approach to reduce the environmental impact of manufacturing. The system approach is developed by using a process-based holistic method for upstream analysis and source reduction of the environmental impact of manufacturing. The system approach developed consists of three components of a manufacturing system: technology, energy and material, and is useful for sustainable manufacturing as it establishes a clear link between manufacturing system components and its overall sustainability performance, and provides a framework for environmental impact reductions. In this dissertation, the system approach developed is applied for environmental impact reduction of a semiconductor nano-scale manufacturing system, with three case scenarios analyzed in depth on manufacturing process improvement, clean energy supply, and toxic chemical material selection. The analysis on manufacturing process improvement is conducted on Atomic Layer Deposition of Al2O3 dielectric gate on semiconductor microelectronics devices. Sustainability performance and scale-up impact of the ALD technology in terms of environmental emissions, energy consumption, nano-waste generation and manufacturing productivity are systematically investigated and the ways to improve the sustainability of the ALD technology are successfully developed. The clean energy supply is studied using solar photovoltaic, wind, and fuel cells systems for electricity generation. Environmental savings from each clean energy supply over grid power are quantitatively analyzed, and costs for greenhouse gas reductions on each clean energy supply are comparatively studied. For toxic chemical material selection, an innovative schematic method is developed as a visual decision tool for characterizing and benchmarking the human health impact of toxic chemicals, with a case study conducted on six chemicals commonly used as solvents in semiconductor manufacturing. Reliability of

A novel intermembrane space–targeting signal docks cysteines onto Mia40 during mitochondrial oxidative folding

PubMed Central

Sideris, Dionisia P.; Petrakis, Nikos; Katrakili, Nitsa; Mikropoulou, Despina; Gallo, Angelo; Ciofi-Baffoni, Simone; Banci, Lucia; Bertini, Ivano

2009-01-01

Mia40 imports Cys-containing proteins into the mitochondrial intermembrane space (IMS) by ensuring their Cys-dependent oxidative folding. In this study, we show that the specific Cys of the substrate involved in docking with Mia40 is substrate dependent, the process being guided by an IMS-targeting signal (ITS) present in Mia40 substrates. The ITS is a 9-aa internal peptide that (a) is upstream or downstream of the docking Cys, (b) is sufficient for crossing the outer membrane and for targeting nonmitochondrial proteins, (c) forms an amphipathic helix with crucial hydrophobic residues on the side of the docking Cys and dispensable charged residues on the other side, and (d) fits complementary to the substrate cleft of Mia40 via hydrophobic interactions of micromolar affinity. We rationalize the dual function of Mia40 as a receptor and an oxidase in a two step–specific mechanism: an ITS-guided sliding step orients the substrate noncovalently, followed by docking of the substrate Cys now juxtaposed to pair with the Mia40 active Cys. PMID:20026652

Measuring the electronic transport properties of individual nano-objects under high pressures

NASA Astrophysics Data System (ADS)

Caillier, C.; Ayari, A.; Le Floch, S.; Féret, H.; Guiraud, G.; San-Miguel, A.

2011-09-01

We describe a setup to carry out electronic transport measurements under high pressures on individual nano-objects. It is based on a home-automated three-stage gas compressor working with argon or helium up to 1 GPa. The setup was successfully tested on contacted individual nanotubes, for which we evidence strong evolutions of the transport properties. These evolutions are related to fundamental issues such as the modification of the nano-object contact resistance, the pressure-induced modification of the nano-object geometry or pressure-induced changes in the intrinsic electronic properties of the nanosystem. A cryostat has also been adapted to the pressure cell, allowing combined pressure and temperature experiments down to 12 K.

Optimization of perfluoro nano-scale emulsions: the importance of particle size for enhanced oxygen transfer in biomedical applications.

PubMed

Fraker, Christopher A; Mendez, Armando J; Inverardi, Luca; Ricordi, Camillo; Stabler, Cherie L

2012-10-01

Nano-scale emulsification has long been utilized by the food and cosmetics industry to maximize material delivery through increased surface area to volume ratios. More recently, these methods have been employed in the area of biomedical research to enhance and control the delivery of desired agents, as in perfluorocarbon emulsions for oxygen delivery. In this work, we evaluate critical factors for the optimization of PFC emulsions for use in cell-based applications. Cytotoxicity screening revealed minimal cytotoxicity of components, with the exception of one perfluorocarbon utilized for emulsion manufacture, perfluorooctylbromide (PFOB), and specific w% limitations of PEG-based surfactants utilized. We optimized the manufacture of stable nano-scale emulsions via evaluation of: component materials, emulsification time and pressure, and resulting particle size and temporal stability. The initial emulsion size was greatly dependent upon the emulsion surfactant tested, with pluronics providing the smallest size. Temporal stability of the nano-scale emulsions was directly related to the perfluorocarbon utilized, with perfluorotributylamine, FC-43, providing a highly stable emulsion, while perfluorodecalin, PFD, coalesced over time. The oxygen mass transfer, or diffusive permeability, of the resulting emulsions was also characterized. Our studies found particle size to be the critical factor affecting oxygen mass transfer, as increased micelle size resulted in reduced oxygen diffusion. Overall, this work demonstrates the importance of accurate characterization of emulsification parameters in order to generate stable, reproducible emulsions with the desired bio-delivery properties. Copyright © 2012 Elsevier B.V. All rights reserved.

Computing fluid-particle interaction forces for nano-suspension droplet spreading: molecular dynamics simulations

NASA Astrophysics Data System (ADS)

Zhou, Weizhou; Shi, Baiou; Webb, Edmund

2017-11-01

Recently, there are many experimental and theoretical studies to understand and control the dynamic spreading of nano-suspension droplets on solid surfaces. However, fundamental understanding of driving forces dictating the kinetics of nano-suspension wetting and spreading, especially capillary forces that manifest during the process, is lacking. Here, we present results from atomic scale simulations that were used to compute forces between suspended particles and advancing liquid fronts. The role of nano-particle size, particle loading, and interaction strength on forces computed from simulations will be discussed. Results demonstrate that increasing the particle size dramatically changes observed wetting behavior from depinning to pinning. From simulations on varying particle size, a relationship between computed forces and particle size is advanced and compared to existing expressions in the literature. High particle loading significantly slowed spreading kinetics, by introducing tortuous transport paths for liquid delivery to the advancing contact line. Lastly, we show how weakening the interaction between the particle and the underlying substrate can change a system from exhibiting pinning behavior to de-pinning.

Development of the Contact Lens User Experience: CLUE Scales

PubMed Central

Wirth, R. J.; Edwards, Michael C.; Henderson, Michael; Henderson, Terri; Olivares, Giovanna; Houts, Carrie R.

2016-01-01

ABSTRACT Purpose The field of optometry has become increasingly interested in patient-reported outcomes, reflecting a common trend occurring across the spectrum of healthcare. This article reviews the development of the Contact Lens User Experience: CLUE system designed to assess patient evaluations of contact lenses. CLUE was built using modern psychometric methods such as factor analysis and item response theory. Methods The qualitative process through which relevant domains were identified is outlined as well as the process of creating initial item banks. Psychometric analyses were conducted on the initial item banks and refinements were made to the domains and items. Following this data-driven refinement phase, a second round of data was collected to further refine the items and obtain final item response theory item parameters estimates. Results Extensive qualitative work identified three key areas patients consider important when describing their experience with contact lenses. Based on item content and psychometric dimensionality assessments, the developing CLUE instruments were ultimately focused around four domains: comfort, vision, handling, and packaging. Item response theory parameters were estimated for the CLUE item banks (377 items), and the resulting scales were found to provide precise and reliable assignment of scores detailing users’ subjective experiences with contact lenses. Conclusions The CLUE family of instruments, as it currently exists, exhibits excellent psychometric properties. PMID:27383257

Linear arrangements of nano-scale ferromagnetic particles spontaneously formed in a copper-base Cu-Ni-Co alloy

NASA Astrophysics Data System (ADS)

Sakakura, Hibiki; Kim, Jun-Seop; Takeda, Mahoto

2018-03-01

We have investigated the influence of magnetic interactions on the microstructural evolution of nano-scale granular precipitates formed spontaneously in an annealed Cu-20at%Ni-5at%Co alloy and the associated changes of magnetic properties. The techniques used included transmission electron microscopy, superconducting quantum interference device (SQUID) magnetometry, magneto-thermogravimetry (MTG), and first-principles calculations based on the method of Koster-Korringa-Rostker with the coherent potential approximation. Our work has revealed that the nano-scale spherical and cubic precipitates which formed on annealing at 873 K and 973 K comprise mainly cobalt and nickel with a small amount of copper, and are arranged in the 〈1 0 0〉 direction of the copper matrix. The SQUID and MTG measurements suggest that magnetic properties such as coercivity and Curie temperature are closely correlated with the microstructure. The combination of results suggests that magnetic interactions between precipitates during annealing can explain consistently the observed precipitation phenomena.

Enhanced electronic excitation energy transfer between dye molecules incorporated in nano-scale media with apparent fractal dimensionality

NASA Astrophysics Data System (ADS)

Yefimova, Svetlana L.; Rekalo, Andrey M.; Gnap, Bogdan A.; Viagin, Oleg G.; Sorokin, Alexander V.; Malyukin, Yuri V.

2014-09-01

In the present study, we analyze the efficiency of Electronic Excitation Energy Transfer (EEET) between two dyes, an energy donor (D) and acceptor (A), concentrated in structurally heterogeneous media (surfactant micelles, liposomes, and porous SiO2 matrices). In all three cases, highly effective EEET in pairs of dyes has been found and cannot be explained by Standard Förster-type theory for homogeneous solutions. Two independent approaches based on the analysis of either the D relative quantum yield () or the D fluorescence decay have been used to study the deviation of experimental results from the theoretical description of EEET process. The observed deviation is quantified by the apparent fractal distribution of molecules parameter . We conclude that the highly effective EEET observed in the nano-scale media under study can be explained by both forced concentration of the hydrophobic dyes within nano-volumes and non-uniform cluster-like character of the distribution of D and A dye molecules within nano-volumes.

Replication of cicada wing's nano-patterns by hot embossing and UV nanoimprinting.

PubMed

Hong, Sung-Hoon; Hwang, Jaeyeon; Lee, Heon

2009-09-23

The hydrophobicity of the cicada wing originates from its naturally occurring, surface nano-structure. The nano-structure of the cicada wing consists of an array of nano-sized pillars, 100 nm in diameter and 300 nm in height. In this study, the nano-structure of the cicada wing was successfully duplicated by using hot embossing lithography and UV nanoimprint lithography (NIL). The diameter and pitch of replication were the same as those of the original cicada wing and the height was a little smaller than that of the original master. The transmittance of the hot embossed PVC film was increased by 2-6% compared with that of the bare PVC film. The hydrophobicity was measured by water contact angle measurements. The water contact angle of the replica, made of UV cured polymer, was 132 degrees +/- 2 degrees , which was slightly lower than that of the original cicada wing (138 degrees +/- 2 degrees ), but much higher than that of the UV cured polymer surface without any nano-sized pillars (86 degrees ).

Replication of cicada wing's nano-patterns by hot embossing and UV nanoimprinting

NASA Astrophysics Data System (ADS)

Hong, Sung-Hoon; Hwang, Jaeyeon; Lee, Heon

2009-09-01

The hydrophobicity of the cicada wing originates from its naturally occurring, surface nano-structure. The nano-structure of the cicada wing consists of an array of nano-sized pillars, 100 nm in diameter and 300 nm in height. In this study, the nano-structure of the cicada wing was successfully duplicated by using hot embossing lithography and UV nanoimprint lithography (NIL). The diameter and pitch of replication were the same as those of the original cicada wing and the height was a little smaller than that of the original master. The transmittance of the hot embossed PVC film was increased by 2-6% compared with that of the bare PVC film. The hydrophobicity was measured by water contact angle measurements. The water contact angle of the replica, made of UV cured polymer, was 132° ± 2°, which was slightly lower than that of the original cicada wing (138° ± 2°), but much higher than that of the UV cured polymer surface without any nano-sized pillars (86°).

Measurement profiles of nano-scale ion beam for optimized radiation energy losses

NASA Astrophysics Data System (ADS)

Woo, T. H.; Cho, H. S.

2011-10-01

The behavior of charged particles is investigated for nano-scale ion beam therapy using a medical accelerator. Computational work is performed for the Bragg-peak simulation, which is focused on human organ material of pancreas and thyroid. The Results show that the trends of the dose have several different kinds of distributions. Before constructing a heavy ion collider, this study can give us the reliability of the therapeutic effect. Realistic treatment using human organs is calculated in a simple and cost effective manner using the computational code, the Stopping and Range of Ions in Matter 2008 (SRIM 2008). Considering the safety of the therapy, it is suggested to give a patient orient planning of the cancer therapy. The energy losses in ionization and phonon are analyzed, which are the behaviors in the molecular level nano-scopic investigation. The different fluctuations are shown at 150 MeV, where the lowest temperature is found in proton and pancreas case. Finally, the protocol for the radiation therapy is constructed by the simulation in which the procedure for a better therapy is selected. An experimental measurement incorporated with the simulations could be programmed by this protocol.

Detecting Nano-Scale Vibrations in Rotating Devices by Using Advanced Computational Methods

PubMed Central

del Toro, Raúl M.; Haber, Rodolfo E.; Schmittdiel, Michael C.

2010-01-01

This paper presents a computational method for detecting vibrations related to eccentricity in ultra precision rotation devices used for nano-scale manufacturing. The vibration is indirectly measured via a frequency domain analysis of the signal from a piezoelectric sensor attached to the stationary component of the rotating device. The algorithm searches for particular harmonic sequences associated with the eccentricity of the device rotation axis. The detected sequence is quantified and serves as input to a regression model that estimates the eccentricity. A case study presents the application of the computational algorithm during precision manufacturing processes. PMID:22399918

The nano-epsilon dot method for strain rate viscoelastic characterisation of soft biomaterials by spherical nano-indentation.

PubMed

Mattei, G; Gruca, G; Rijnveld, N; Ahluwalia, A

2015-10-01

Nano-indentation is widely used for probing the micromechanical properties of materials. Based on the indentation of surfaces using probes with a well-defined geometry, the elastic and viscoelastic constants of materials can be determined by relating indenter geometry and measured load and displacement to parameters which represent stress and deformation. Here we describe a method to derive the viscoelastic properties of soft hydrated materials at the micro-scale using constant strain rates and stress-free initial conditions. Using a new self-consistent definition of indentation stress and strain and corresponding unique depth-independent expression for indentation strain rate, the epsilon dot method, which is suitable for bulk compression testing, is transformed to nano-indentation. We demonstrate how two materials can be tested with a displacement controlled commercial nano-indentor using the nano-espilon dot method (nano-ε̇M) to give values of instantaneous and equilibrium elastic moduli and time constants with high precision. As samples are tested in stress-free initial conditions, the nano-ε̇M could be useful for characterising the micro-mechanical behaviour of soft materials such as hydrogels and biological tissues at cell length scales. Copyright © 2015 Elsevier Ltd. All rights reserved.

Nano-Gap Embedded Plasmonic Gratings for Surface Plasmon Enhanced Fluorescence

NASA Astrophysics Data System (ADS)

Bhatnagar, Kunal; Bok, Sangho; Korampally, Venumadhav; Gangopadhyay, Shubhra

2012-02-01

Plasmonic nanostructures have been extensively used in the past few decades for applications in sub-wavelength optics, data storage, optoelectronic circuits, microscopy and bio-photonics. The enhanced electromagnetic field produced at the metal/dielectric interface by the excitation of surface plasmons via incident radiation can be used for signal enhancement in fluorescence and surface enhanced Raman scattering studies. Novel plasmonic structures on the sub wavelength scale have been shown to provide very efficient and extreme light concentration at the nano-scale. The enhanced electric field produced within a few hundred nanometers of these structures can be used to excite fluorophores in the surrounding environment. Fluorescence based bio-detection and bio-imaging are two of the most important tools in the life sciences. Improving the qualities and capabilities of fluorescence based detectors and imaging equipment has been a big challenge to the industry manufacturers. We report the novel fabrication of nano-gap embedded periodic grating substrates on the nanoscale using micro-contact printing and polymethylsilsesquioxane (PMSSQ) polymer. Fluorescence enhancement of up to 118 times was observed with these silver nanostructures in conjugation with Rhodamine-590 fluorescent dye. These substrates are ideal candidates for low-level fluorescence detection and single molecule imaging.

Comparing the Efficacy of Three Different Nano-scale Bone Substitutes: In vivo Study.

PubMed

Razavi, Sayed Mohammad; Rismanchian, Mansour; Jafari-Pozve, Nasim; Nosouhian, Saied

2017-01-01

Synthetic biocompatible bone substitutions have been used widely for bone tissue regeneration as they are safe and effective. The aim of this animal study is to compare the effectiveness of three different biocompatible bone substitutes, including nano-hydroxyapatite (nano-HA) nano-bioglass (nano-BG) and forstrite scaffolds. In this interventional and experimental study, four healthy dogs were anesthetized, and the first to fourth premolars were extracted in each quadrant. After healing, the linear incision on the crestal ridge from molar to anterior segment prepared in each quadrant and 16 defects in each dog were prepared. Nano-HA, nano-BG, and forstrite scaffold was prepared according to the size of defects and placed in the 12 defects randomly, four defects remained as a control group. The dogs were sacrificed in four time intervals (15, 30, 45, and 60 days after) and the percentage of different types of regenerated bones (lamellar and woven) and connective tissue were recorded in histological process. The data were analyzed using Mann-Whitney test (α = 0.05). The difference in nano-HA and nano-BG with the control group was significant in three-time intervals regarding the amount of bone formation ( P < 0.01). After 15 days, the nano-HA showed the highest amount of woven and lamellar bone regeneration (18.37 ± 1.06 and 30.44 ± 0.54). Nano-HA and nano-BG groups showed a significant amount of bone regeneration, especially after 30 days, but paying more surveys and observation to these materials as bone substitutes seem to be needed.

Application Of Positron Beams For The Characterization Of Nano-scale Pores In Thin Films

NASA Astrophysics Data System (ADS)

Hirata, K.; Ito, K.; Kobayashi, Y.; Suzuki, R.; Ohdaira, T.; Eijt, S. W. H.; Schut, H.; van Veen, A.

2003-08-01

We applied three positron annihilation techniques, positron 3γ-annihilation spectroscopy, positron annihilation lifetime spectroscopy, and angular correlation of annihilation radiation, to the characterization of nano-scale pores in thin films by combining them with variable-energy positron beams. Characterization of pores in thin films is an important part of the research on various thin films of industrial importance. The results of our recent studies on pore characterization of thin films by positron beams will be reported here.

Microstructure and physical properties of nano-biocomposite films based on cassava starch and laponite.

PubMed

Valencia, Germán Ayala; Luciano, Carla Giovana; Lourenço, Rodrigo Vinicius; do Amaral Sobral, Paulo José

2018-02-01

The aim of this research was to study the effects of laponite concentrations on some properties of nano-biocomposite films based on cassava starch, focusing mainly the relation between the properties of the surface microstructure and roughness, water contact angle and gloss. Nano-biocomposite films were produced by casting. We analyzed gloss, color, opacity, water contact angle, crystallinity by X-ray diffraction, and microstructure by scanning electron microscopy and atomic force microscopy. Texture parameters (energy, entropy and fractal dimension) were extracted from micrographs. We observed a great impact of laponite in the morphology of nano-biocomposite films. Texture parameters correlated with surface heterogeneity and roughness. Finally, surface roughness affected the surface hydrophilicity of nano-biocomposite films. Laponite platelets were exfoliated and/or intercalated with amylose and amylopectin chains. This research reports new information on the effects of laponite concentrations on the morphological, optical and wetting properties of nano-biocomposite films aiming future industrial applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Non-contact analysis of the adsorptive ink capacity of nano silica pigments on a printing coating base.

PubMed

Jiang, Bo; Huang, Yu Dong

2014-01-01

Near infrared spectra combined with partial least squares were proposed as a means of non-contact analysis of the adsorptive ink capacity of recording coating materials in ink jet printing. First, the recording coating materials were prepared based on nano silica pigments. 80 samples of the recording coating materials were selected to develop the calibration of adsorptive ink capacity against ink adsorption (g/m2). The model developed predicted samples in the validation set with r2  = 0.80 and SEP = 1.108, analytical results showed that near infrared spectra had significant potential for the adsorption of ink capacity on the recording coating. The influence of factors such as recording coating thickness, mass ratio silica: binder-polyvinyl alcohol and the solution concentration on the adsorptive ink capacity were studied. With the help of the near infrared spectra, the adsorptive ink capacity of a recording coating material can be rapidly controlled.

Comparing the Efficacy of Three Different Nano-scale Bone Substitutes: In vivo Study

PubMed Central

Razavi, Sayed Mohammad; Rismanchian, Mansour; Jafari-pozve, Nasim; Nosouhian, Saied

2017-01-01

Background: Synthetic biocompatible bone substitutions have been used widely for bone tissue regeneration as they are safe and effective. The aim of this animal study is to compare the effectiveness of three different biocompatible bone substitutes, including nano-hydroxyapatite (nano-HA) nano-bioglass (nano-BG) and forstrite scaffolds. Materials and Methods: In this interventional and experimental study, four healthy dogs were anesthetized, and the first to fourth premolars were extracted in each quadrant. After healing, the linear incision on the crestal ridge from molar to anterior segment prepared in each quadrant and 16 defects in each dog were prepared. Nano-HA, nano-BG, and forstrite scaffold was prepared according to the size of defects and placed in the 12 defects randomly, four defects remained as a control group. The dogs were sacrificed in four time intervals (15, 30, 45, and 60 days after) and the percentage of different types of regenerated bones (lamellar and woven) and connective tissue were recorded in histological process. The data were analyzed using Mann–Whitney test (α = 0.05). Results: The difference in nano-HA and nano-BG with the control group was significant in three-time intervals regarding the amount of bone formation (P < 0.01). After 15 days, the nano-HA showed the highest amount of woven and lamellar bone regeneration (18.37 ± 1.06 and 30.44 ± 0.54). Conclusion: Nano-HA and nano-BG groups showed a significant amount of bone regeneration, especially after 30 days, but paying more surveys and observation to these materials as bone substitutes seem to be needed. PMID:28603705

Minimum ignition temperature of nano and micro Ti powder clouds in the presence of inert nano TiO2 powder.

PubMed

Yuan, Chunmiao; Amyotte, Paul R; Hossain, Md Nur; Li, Chang

2014-06-30

Minimum ignition temperature (MIT) of micro Ti powder increased gradually with increases in nano-sized TiO2 employed as an inertant. Solid TiO2 inertant significantly reduced ignition hazard of micro Ti powder in contact with hot surfaces. The MIT of nano Ti powder remained low (583 K), however, even with 90% TiO2. The MIT of micro Ti powder, when mixed with nano Ti powder at concentrations as low as 10%, decreased so dramatically that its application as a solid fuel may be possible. A simple MIT model was proposed for aggregate particle size estimation and better understanding of the inerting effect of nano TiO2 on MIT. Estimated particle size was 1.46-1.51 μm larger than that in the 20-L sphere due to poor dispersion in the BAM oven. Calculated MITs were lower than corresponding empirically determined values for micro Ti powder because nano-sized TiO2 coated the micro Ti powder, thereby decreasing its reaction kinetics. In the case of nano Ti powder, nano-sized TiO2 facilitated dispersion of nano Ti powder which resulted in a calculated MIT that was greater than the experimentally determined value. Copyright © 2014 Elsevier B.V. All rights reserved.

Irradiation Induced Fluorescence Enhancement in PEGylated Cyanine-based NIR Nano- and Meso-scale GUMBOS

PubMed Central

Lu, Chengfei; Das, Susmita; Magut, Paul K. S.; Li, Min; El Zahab, Bilal; Warner, Isiah M.

2014-01-01

We report on the synthesis and characterization of a PEGylated IR786 GUMBOS (Group of Uniform Materials Based on Organic Salts). The synthesis of this material was accomplished using a three step protocol: (1) substitution of chloride on the cyclohexenyl ring in the heptamethine chain of IR786 by 6-aminohexanoic acid, (2) grafting of methoxy poly ethyleneglycol (MeOPEG) onto the 6-aminohexanoic acid via an esterification reaction, and (3) anion exchange between [PEG786][I] and lithium bis(trifluoromethylsulfonyl)imide (LiNTf2) or sodium bis(2-ethylhexyl)sulfosuccinate (AOT) in order to obtain PEG786 GUMBOS. Examination of spectroscopic data for this PEG786 GUMBOS indicates a large stokes shift (122 nm). It was observed that this PEG786 GUMBOS associates in aqueous solution to form nano-and meso-scale self-assemblies with sizes ranging from 100 to 220 nm. These nano- and meso-scale GUMBOS are also able to resist nonspecific binding to proteins. PEGylation of the original IR786 leads to reduced cytotoxicity. In addition, it was noted that anions, such as NTf2 and AOT, play a significant role in improving the photostability of PEG786 GUMBOS. Irradiation-induced J aggregation in [PEG786][NTf2] and to some extent in [PEG786][AOT] produced enhanced photostability. This observation was supported by use of both steady state and time-resolved fluorescence measurements. PMID:22957476

Infinite Coordination Polymer Nano- and Micro-Particles

DTIC Science & Technology

2015-06-12

Mirkin, Tobin J. Marks, Joseph T. Hupp. SiO2 Aerogel-templated, Porous TiO2 Photoanodes for Enhanced Performances in Dye-Sensitized Solar Cells ...nano-scale ICPs and their selective surface functionalization, we examined if indeed these ICP-DNA hybrid structures could enter cells and...surface functionalization. In particular, we aimed to utilize this fundamental understanding for the realization of nano-scale ICP-biomolecule hybrids

Electron-beam induced nano-etching of suspended graphene

PubMed Central

Sommer, Benedikt; Sonntag, Jens; Ganczarczyk, Arkadius; Braam, Daniel; Prinz, Günther; Lorke, Axel; Geller, Martin

2015-01-01

Besides its interesting physical properties, graphene as a two-dimensional lattice of carbon atoms promises to realize devices with exceptional electronic properties, where freely suspended graphene without contact to any substrate is the ultimate, truly two-dimensional system. The practical realization of nano-devices from suspended graphene, however, relies heavily on finding a structuring method which is minimally invasive. Here, we report on the first electron beam-induced nano-etching of suspended graphene and demonstrate high-resolution etching down to ~7 nm for line-cuts into the monolayer graphene. We investigate the structural quality of the etched graphene layer using two-dimensional (2D) Raman maps and demonstrate its high electronic quality in a nano-device: A 25 nm-wide suspended graphene nanoribbon (GNR) that shows a transport gap with a corresponding energy of ~60 meV. This is an important step towards fast and reliable patterning of suspended graphene for future ballistic transport, nano-electronic and nano-mechanical devices. PMID:25586495

Comparative study on predicting Young's modulus of graphene sheets using nano-scale continuum mechanics approach

NASA Astrophysics Data System (ADS)

Rafiee, Roham; Eskandariyun, Amirali

2017-06-01

In this research, nano-scale continuum modeling is employed to predict Young's modulus of graphene sheet. The lattice nano-structure of a graphene sheet is replaced with a discrete space-frame structure simulating carbon-carbon bonds with either beam or spring elements. A comparative study is carried out to check the influence of employed elements on estimated Young's moduli of graphene sheets in both horizontal and vertical directions. A detailed analysis is also conducted to investigate the influence of graphene sheet sizes on its Young's modulus and corresponding aspect ratios that unwelcomed end effects disappear on the results are extracted. At the final stage, defected graphene sheets suffering from vacancy defects are investigated through a stochastic analysis taking into account both number of defects and their locations as random parameters. The reduction level in the Young's moduli of defected graphene sheets compared with non-defected ones is analyzed and reported.

Structural and optical characterization of GaAs nano-crystals selectively grown on Si nano-tips by MOVPE.

PubMed

Skibitzki, Oliver; Prieto, Ivan; Kozak, Roksolana; Capellini, Giovanni; Zaumseil, Peter; Arroyo Rojas Dasilva, Yadira; Rossell, Marta D; Erni, Rolf; von Känel, Hans; Schroeder, Thomas

2017-03-01

We present the nanoheteroepitaxial growth of gallium arsenide (GaAs) on nano-patterned silicon (Si) (001) substrates fabricated using a CMOS technology compatible process. The selective growth of GaAs nano-crystals (NCs) was achieved at 570 °C by MOVPE. A detailed structure and defect characterization study of the grown nano-heterostructures was performed using scanning transmission electron microscopy, x-ray diffraction, micro-Raman, and micro-photoluminescence (μ-PL) spectroscopy. The results show single-crystalline, nearly relaxed GaAs NCs on top of slightly, by the SiO 2 -mask compressively strained Si nano-tips (NTs). Given the limited contact area, GaAs/Si nanostructures benefit from limited intermixing in contrast to planar GaAs films on Si. Even though a few growth defects (e.g. stacking faults, micro/nano-twins, etc) especially located at the GaAs/Si interface region were detected, the nanoheterostructures show intensive light emission, as investigated by μ-PL spectroscopy. Achieving well-ordered high quality GaAs NCs on Si NTs may provide opportunities for superior electronic, photonic, or photovoltaic device performances integrated on the silicon technology platform.

A comparative study of gelatin and starch-based nano-composite films modified by nano-cellulose and chitosan for food packaging applications.

PubMed

Noorbakhsh-Soltani, S M; Zerafat, M M; Sabbaghi, S

2018-06-01

Environmental concerns have led to extensive research for replacing polymer-based food packaging with bio-nano-composites. In this study, incorporation of nano-cellulose into gelatin and starch matrices is investigated for this purpose. Chitosan is used to improve mechanical, anti-fungal and waterproof properties. Experiments are designed and analyzed using response surface methodology. Nano-Cellulose is synthesized via acid hydrolysis and incorporated in base matrices through wet processing. Also, tensile strength test, food preservation, transparency in visible and UV and water contact angle are performed on the nano-composite films. DSC/TGA and air permeability tests are also performed on the optimal films. The results show that increasing nano-cellulose composition to 10% leads to increase the tensile strength at break to 8121 MN/m 2 and decrease the elongation at break. Also, increasing chitosan composition from 5% to 30% can enhance food preservation up to 15 days. Copyright © 2018 Elsevier Ltd. All rights reserved.

Ultra-low specific contact resistivity (1.4 × 10-9 Ω.cm2) for metal contacts on in-situ Ga-doped Ge0.95Sn0.05 film

NASA Astrophysics Data System (ADS)

Wu, Ying; Luo, Sheng; Wang, Wei; Masudy-Panah, Saeid; Lei, Dian; Liang, Gengchiau; Gong, Xiao; Yeo, Yee-Chia

2017-12-01

A heavily Ga-doped Ge0.95Sn0.05 layer was grown on the Ge (100) substrate by molecular beam epitaxy (MBE), achieving an active doping concentration of 1.6 × 1020 cm-3 without the use of ion implantation and high temperature annealing that could cause Sn precipitation or surface segregation. An advanced nano-scale transfer length method was used to extract the specific contact resistivity ρc between the metal and the heavily doped p-Ge0.95Sn0.05 layer. By incorporating Sn into Ge and in-situ Ga doping during the MBE growth, an ultra-low ρc of 1.4 × 10-9 Ω.cm2 was achieved, which is 50% lower than the ρc of p+-Ge control and is also the lowest value obtained for metal/p-type semiconductor contacts.

Novel Organic Field Effect Transistors via Nano-Modification

DTIC Science & Technology

2005-07-01

mobility by using two kinds of nano-scale films. One is to apply the photoalignment method on a nano-scale film to control the orientation of pentacene ...scale film (polymer electrolyte) to control moving of ions in/out an active semiconducor, pentacene or conducting polymer, for improving carrier...mobility. In this project, pentacene or a series of conducting polymers, such as the derivatives of PANI and P3HT will be patterned and manufactured in

Antibacterial properties of nano-silver coated PEEK prepared through magnetron sputtering.

PubMed

Liu, Xiuju; Gan, Kang; Liu, Hong; Song, Xiaoqing; Chen, Tianjie; Liu, Chenchen

2017-09-01

We aimed to investigate the cytotoxicity and antibacterial properties of nano-silver-coated polyetheretherketone (PEEK) produced through magnetron sputtering and provide a theoretical basis for its use in clinical applications. The surfaces of PEEKs were coated with nano-silver at varying thicknesses (3, 6, 9, and 12nm) through magnetron sputtering technology. The resulting coated PEEK samples were classified into the following groups according to the thickness of the nano-silver coating: PEEK-3 (3nm), PEEK-6 (6nm), PEEK-9 (9nm), PEEK-12 (12nm), and PEEK control group. The surface microstructure and composition of each sample were observed by scanning electron microscopy (SEM), atomic force microscopy (AFM), and energy dispersive spectrum (EDS) analysis. The water contact angle of each sample was then measured by contact angle meters. A cell counting kit (CCK-8) was used to analyze the cytotoxicity of the mouse fibroblast cells (L929) in the coated groups (n=5) and group test samples (n=6), negative control (polyethylene, PE) (n=6), and positive control group (phenol) (n=6). The antibacterial properties of the samples were tested by co-culturing Streptococcus mutans and Straphylococcus aureus. The bacteria that adhered to the surface of samples were observed by SEM. The antibacterial adhesion ability of each sample was then evaluated. SEM and AFM analysis results showed that the surfaces of control group samples were smooth but compact. Homogeneous silver nano-particles (AgNPs) and nano-silver coating were uniformly distributed on the surface of the coated group samples. Compared with the control samples, the nano-silver coated samples had a significant increase in surface roughness (P<0.05) as the thickness of their nano-silver coating increased. EDS analysis showed that not only C and O but also Ag were present on the surface of the coated samples. Moreover, the water contact angle of modified samples significantly increased after nano-silver coating modification

Application of Contact Mode AFM to Manufacturing Processes

NASA Astrophysics Data System (ADS)

Giordano, Michael A.; Schmid, Steven R.

A review of the application of contact mode atomic force microscopy (AFM) to manufacturing processes is presented. A brief introduction to common experimental techniques including hardness, scratch, and wear testing is presented, with a discussion of challenges in the extension of manufacturing scale investigations to the AFM. Differences between the macro- and nanoscales tests are discussed, including indentation size effects and their importance in the simulation of processes such as grinding. The basics of lubrication theory are presented and friction force microscopy is introduced as a method of investigating metal forming lubrication on the nano- and microscales that directly simulates tooling/workpiece asperity interactions. These concepts are followed by a discussion of their application to macroscale industrial manufacturing processes and direct correlations are made.

Effect of Spreading Time on Contact Angle of Nanofluid on the Surface of Stainless Steel AISI 316 and Zircalloy 4

NASA Astrophysics Data System (ADS)

Prajitno, D. H.; Trisnawan, V.; Syarif, D. G.

2017-05-01

The solid surface tension plays an important role in the heat and mass transfer system for heat exchanger equipment. In the nuclear power plant industry, the stainless steel AISI 316 and Zircalloy 4 have been used for long time as structure materials. The purpose of the experimental is to study solid state surface tension behavior by measure contact angle Nano fluid contain nano particle alumina on metal surface of stainless steel AISI 316 and Zircalloy 4 by sessile drop method. The experiment is to measure the static contact angle and drop nano fluid contains nano particle alumina on stainless steel 316 and zircalloy 4 with different spreading time from 1 to 30 minute. It was observed that stainless steel 316 and zircalloy 4 lose their hydrophobic properties with increasing elapsed time during drop of nano fluid on the surface of alloy. As a result the contact angle of nano fluid on surface of metal is decrease with increasing elapsed time. While the magnitude diameter of drop nano fluid and wetting surface is increase with increasing elapsed time on the surface of the stainless steel SS 316 and Zircalloy 4.

Non-Contact Analysis of the Adsorptive Ink Capacity of Nano Silica Pigments on a Printing Coating Base

PubMed Central

Jiang, Bo; Huang, Yu Dong

2014-01-01

Near infrared spectra combined with partial least squares were proposed as a means of non-contact analysis of the adsorptive ink capacity of recording coating materials in ink jet printing. First, the recording coating materials were prepared based on nano silica pigments. 80 samples of the recording coating materials were selected to develop the calibration of adsorptive ink capacity against ink adsorption (g/m2). The model developed predicted samples in the validation set with r2  = 0.80 and SEP  = 1.108, analytical results showed that near infrared spectra had significant potential for the adsorption of ink capacity on the recording coating. The influence of factors such as recording coating thickness, mass ratio silica: binder-polyvinyl alcohol and the solution concentration on the adsorptive ink capacity were studied. With the help of the near infrared spectra, the adsorptive ink capacity of a recording coating material can be rapidly controlled. PMID:25329464

Electrochemical micro/nano-machining: principles and practices.

PubMed

Zhan, Dongping; Han, Lianhuan; Zhang, Jie; He, Quanfeng; Tian, Zhao-Wu; Tian, Zhong-Qun

2017-03-06

Micro/nano-machining (MNM) is becoming the cutting-edge of high-tech manufacturing because of the increasing industrial demand for supersmooth surfaces and functional three-dimensional micro/nano-structures (3D-MNS) in ultra-large scale integrated circuits, microelectromechanical systems, miniaturized total analysis systems, precision optics, and so on. Taking advantage of no tool wear, no surface stress, environmental friendliness, simple operation, and low cost, electrochemical micro/nano-machining (EC-MNM) has an irreplaceable role in MNM. This comprehensive review presents the state-of-art of EC-MNM techniques for direct writing, surface planarization and polishing, and 3D-MNS fabrications. The key point of EC-MNM is to confine electrochemical reactions at the micro/nano-meter scale. This review will bring together various solutions to "confined reaction" ranging from electrochemical principles through technical characteristics to relevant applications.

Biofunctionalization of scaffold material with nano-scaled diamond particles physisorbed with angiogenic factors enhances vessel growth after implantation.

PubMed

Schimke, Magdalena M; Stigler, Robert; Wu, Xujun; Waag, Thilo; Buschmann, Peter; Kern, Johann; Untergasser, Gerold; Rasse, Michael; Steinmüller-Nethl, Doris; Krueger, Anke; Lepperdinger, Günter

2016-04-01

Biofunctionalized scaffold facilitates complete healing of large defects. Biological constraints are induction and ingrowth of vessels. Angiogenic growth factors such as vascular endothelial growth factor or angiopoietin-1 can be bound to nano-scaled diamond particles. Corresponding bioactivities need to be examined after biofunctionalization. We therefore determined the physisorptive capacity of distinctly manufactured, differently sized nDP and the corresponding activities of bound factors. The properties of biofunctionalized nDPs were investigated on cultivated human mesenchymal stem cells and on the developing chicken embryo chorio-allantoic membrane. Eventually porous bone substitution material was coated with nDP to generate an interface that allows biofactor physisorption. Angiopoietin-1 was applied shortly before scaffold implantation into an osseous defect in sheep calvaria. Biofunctionalized scaffolds exhibited significantly increased rates of angiogenesis already one month after implantation. Conclusively, nDP can be used to ease functionalization of synthetic biomaterials. With the advances in nanotechnology, many nano-sized materials have been used in the biomedical field. This is also true for nano-diamond particles (nDP). In this article, the authors investigated the physical properties of functionalized nano-diamond particles in both in-vitro and in-vivo settings. The positive findings would help improve understanding of these nanomaterials in regenerative medicine. Copyright © 2015 Elsevier Inc. All rights reserved.

Infectious disease control using contact tracing in random and scale-free networks

PubMed Central

Kiss, Istvan Z; Green, Darren M; Kao, Rowland R

2005-01-01

Contact tracing aims to identify and isolate individuals that have been in contact with infectious individuals. The efficacy of contact tracing and the hierarchy of traced nodes—nodes with higher degree traced first—is investigated and compared on random and scale-free (SF) networks with the same number of nodes N and average connection K. For values of the transmission rate larger than a threshold, the final epidemic size on SF networks is smaller than that on corresponding random networks. While in random networks new infectious and traced nodes from all classes have similar average degrees, in SF networks the average degree of nodes that are in more advanced stages of the disease is higher at any given time. On SF networks tracing removes possible sources of infection with high average degree. However a higher tracing effort is required to control the epidemic than on corresponding random networks due to the high initial velocity of spread towards the highly connected nodes. An increased latency period fails to significantly improve contact tracing efficacy. Contact tracing has a limited effect if the removal rate of susceptible nodes is relatively high, due to the fast local depletion of susceptible nodes. PMID:16849217

Research progress of nano self - cleaning anti-fouling coatings

NASA Astrophysics Data System (ADS)

Liu, Y.; Zhao, Y. J.; Teng, J. L.; Wang, J. H.; Wu, L. S.; Zheng, Y. L.

2018-01-01

There are many methods of evaluating the performance of nano self-cleaning anti-fouling coatings, such as carbon blacking method, coating reflection coefficient method, glass microbead method, film method, contact angle and rolling angle method, organic degradation method, and the application of performance evaluation method in self-cleaning antifouling coating. For the more, the types of nano self-cleaning anti-fouling coatings based on aqueous media was described, such as photocatalytic self-cleaning coatings, silicone coatings, organic fluorine coatings, fluorosilicone coatings, fluorocarbon coatings, polysilazane self-cleaning coatings. The research and application of different kinds of nano self-cleaning antifouling coatings are anlysised, and the latest research results are summed.

Narrowing of band gap at source/drain contact scheme of nanoscale InAs-nMOS

NASA Astrophysics Data System (ADS)

Mohamed, A. H.; Oxland, R.; Aldegunde, M.; Hepplestone, S. P.; Sushko, P. V.; Kalna, K.

2018-04-01

A multi-scale simulation study of Ni/InAs nano-scale contact aimed for the sub-14 nm technology is carried out to understand material and transport properties at a metal-semiconductor interface. The deposited Ni metal contact on an 11 nm thick InAs channel forms an 8.5 nm thick InAs leaving a 2.5 nm thick InAs channel on a p-type doped (1 × 1016 cm-3) AlAs0.47Sb0.53 buffer. The density functional theory (DFT) calculations reveal a band gap narrowing in the InAs at the metal-semiconductor interface. The one-dimensional (1D) self-consistent Poisson-Schrödinger transport simulations using real-space material parameters extracted from the DFT calculations at the metal-semiconductor interface, exhibiting band gap narrowing, give a specific sheet resistance of Rsh = 90.9 Ω/sq which is in a good agreement with an experimental value of 97 Ω/sq.

Water soluble nano-scale transient material germanium oxide for zero toxic waste based environmentally benign nano-manufacturing

NASA Astrophysics Data System (ADS)

Almuslem, A. S.; Hanna, A. N.; Yapici, T.; Wehbe, N.; Diallo, E. M.; Kutbee, A. T.; Bahabry, R. R.; Hussain, M. M.

2017-02-01

In the recent past, with the advent of transient electronics for mostly implantable and secured electronic applications, the whole field effect transistor structure has been dissolved in a variety of chemicals. Here, we show simple water soluble nano-scale (sub-10 nm) germanium oxide (GeO2) as the dissolvable component to remove the functional structures of metal oxide semiconductor devices and then reuse the expensive germanium substrate again for functional device fabrication. This way, in addition to transiency, we also show an environmentally friendly manufacturing process for a complementary metal oxide semiconductor (CMOS) technology. Every year, trillions of complementary metal oxide semiconductor (CMOS) electronics are manufactured and billions are disposed, which extend the harmful impact to our environment. Therefore, this is a key study to show a pragmatic approach for water soluble high performance electronics for environmentally friendly manufacturing and bioresorbable electronic applications.

Adhesion and proliferation of OCT-1 osteoblast-like cells on micro- and nano-scale topography structured poly(L-lactide).

PubMed

Wan, Yuqing; Wang, Yong; Liu, Zhimin; Qu, Xue; Han, Buxing; Bei, Jianzhong; Wang, Shenguo

2005-07-01

The impact of the surface topography of polylactone-type polymer on cell adhesion was to be concerned because the micro-scale texture of a surface can provide a significant effect on the adhesion behavior of cells on the surface. Especially for the application of tissue engineering scaffold, the pore size could have an influence on cell in-growth and subsequent proliferation. Micro-fabrication technology was used to generate specific topography to investigate the relationship between the cells and surface. In this study the pits-patterned surfaces of polystyrene (PS) film with diameters 2.2 and 0.45 microm were prepared by phase-separation, and the corresponding scale islands-patterned PLLA surface was prepared by a molding technique using the pits-patterned PS as a template. The adhesion and proliferation behavior of OCT-1 osteoblast-like cells morphology on the pits- and islands-patterned surface were characterized by SEM observation, cell attachment efficiency measurement and MTT assay. The results showed that the cell adhesion could be enhanced on PLLA and PS surface with nano-scale and micro-scale roughness compared to the smooth surfaces of the PLLA and PS. The OCT-1 osteoblast-like cells could grow along the surface with two different size islands of PLLA and grow inside the micro-scale pits of the PS. However, the proliferation of cells on the micro- and nano-scale patterned surface has not been enhanced compared with the controlled smooth surface.

Micro/nano moire methods

NASA Astrophysics Data System (ADS)

Asundi, Anand K.; Shang, Haixia; Xie, Huimin; Li, Biao

2003-10-01

Two novel micro/nano moire method, SEM scanning moiré and AFM scanning moire techniques are discussed in this paper. The principle and applications of two scanning moire methods are described in detail. The residual deformation in a polysilicon MEMS cantilever structure with a 5000 lines/mm grating after removing the SiO2 sacrificial layer is accurately measured by SEM scanning moire method. While AFM scanning moire method is used to detect thermal deformation of electronic package components, and formation of nano-moire on a freshly cleaved mica crystal. Experimental results demonstrate the feasibility of these two moire methods, and also show they are effective methods to measure the deformation from micron to nano-scales.

Nano-scale imaging and spectroscopy of plasmonic systems, thermal near-fields, and phase separation in complex oxides

NASA Astrophysics Data System (ADS)

Jones, Andrew C.

Optical spectroscopy represents a powerful characterization technique with the ability to directly interact with the electronic, spin, and lattice excitations in matter. In addition, through implementation of ultrafast techniques, further insight into the real-time dynamics of elementary interactions can be gained. However, the resolution of far-field microscopy techniques is restricted by the diffraction limit setting a spatial resolution limit in the 100s nm to micron range for visible and IR light, respectively. This resolution is too coarse for the characterization of mesoscopic phenomena in condensed matter physics. The development of experimental techniques with nanoscale resolution and sensitivity to optical fields has been a long standing obstacle to the characterization of condensed matter systems on their natural length scales. This dissertation focuses on the fundamental near-field optical properties of surfaces and nanoscale systems as well as the utilization of nano-optical techniques, specifically apertureless scattering-type Scanning Near-field Optical Microscopy (s-SNOM), to characterize said optical properties with nanometer scale resolution. First, the s-SNOM characterization of the field enhancement associated with the localized surface plasmon resonances on metallic structures is discussed. With their ability to localize light, plasmonic nano-structures are promising candidate systems to serve as molecular sensors and nano-photonic devices; however, it is well known that particle morphology and the plasmon resonance alone do not uniquely reflect the details of the local field distribution. Here, I demonstrate the use interferometric s-SNOM for imaging of the near-fields associated with plasmonic resonances of crystalline triangular silver nano-prisms in the visible spectral range. I subsequently show the extension of the concept of a localized plasmon into the mid-IR spectral range with the characterization of near-fields of silver nano

Non-Contact Stiffness Measurement of a Suspended Single Walled Carbon Nanotube Device

NASA Technical Reports Server (NTRS)

Zheng, Yun; Su, Chanmin; Getty, Stephanie

2010-01-01

A new nanoscale electric field sensor was developed for studying triboelectric charging in terrestrial and Martian dust devils. This sensor is capable to measure the large electric fields for large dust devils without saturation. However, to quantify the electric charges and the field strength it is critical to calibrate the mechanical stiffness of the sensor devices. We performed a technical feasibility study of the Nano E-field Sensor stiffness by a non-contact stiffness measurement method. The measurement is based on laser Doppler vibrometer measurement of the thermal noise due to energy flunctuations in the devices. The experiment method provides a novel approach to acquire data that is essential in analyzing the quantitative performance of the E-field Nano Sensor. To carry out the non-contact stiffness measurement, we fabricated a new Single-Walled Carbon Nanotube (SWCNT) E-field sensor with different SWCNTs suspension conditions. The power spectra of the thermal induced displacement in the nano E-field sensor were measured at the accuracy of picometer. The power spectra were then used to derive the mechanical stiffness of the sensors. Effect of suspension conditions on stiffness and sensor sensitivty was discussed. After combined deformation and resistivity measurement, we can compare with our laboratory testing and field testing results. This new non-contact measurement technology can also help to explore to other nano and MEMS devices in the future.

Method for nano-pumping using carbon nanotubes

DOEpatents

Insepov, Zeke [Darien, IL; Hassanein, Ahmed [Bolingbrook, IL

2009-12-15

The present invention relates generally to the field of nanotechnology, carbon nanotubes and, more specifically, to a method and system for nano-pumping media through carbon nanotubes. One preferred embodiment of the invention generally comprises: method for nano-pumping, comprising the following steps: providing one or more media; providing one or more carbon nanotubes, the one or more nanotubes having a first end and a second end, wherein said first end of one or more nanotubes is in contact with the media; and creating surface waves on the carbon nanotubes, wherein at least a portion of the media is pumped through the nanotube.

Scaling for quantum tunneling current in nano- and subnano-scale plasmonic junctions.

PubMed

Zhang, Peng

2015-05-19

When two conductors are separated by a sufficiently thin insulator, electrical current can flow between them by quantum tunneling. This paper presents a self-consistent model of tunneling current in a nano- and subnano-meter metal-insulator-metal plasmonic junction, by including the effects of space charge and exchange correlation potential. It is found that the J-V curve of the junction may be divided into three regimes: direct tunneling, field emission, and space-charge-limited regime. In general, the space charge inside the insulator reduces current transfer across the junction, whereas the exchange-correlation potential promotes current transfer. It is shown that these effects may modify the current density by orders of magnitude from the widely used Simmons' formula, which is only accurate for a limited parameter space (insulator thickness > 1 nm and barrier height > 3 eV) in the direct tunneling regime. The proposed self-consistent model may provide a more accurate evaluation of the tunneling current in the other regimes. The effects of anode emission and material properties (i.e. work function of the electrodes, electron affinity and permittivity of the insulator) are examined in detail in various regimes. Our simple model and the general scaling for tunneling current may provide insights to new regimes of quantum plasmonics.

Fabrication of 1-dimension nano-material-based device and its electrical characteristics

NASA Astrophysics Data System (ADS)

Yang, Xing; Zhou, Zhaoying; Zheng, Fuzhong; Zhang, Min

2008-12-01

In recent years, many kinds of 1-dimension nano-materials (Carbon nanotube, ZnO nanobelt and nanowire etc.) continue to emerge which exhibit distinct and unique electromechanical, piezoelectric, photoelectrical properties. In this paper, a 1-dimension nano-materials-based device was proposed. The bottom-up and top-down combined process were used for constructing CNT-array-based device and ZnO nanowire device. The electrical characteristics of the 1D nano-materials-based devices were also investigated. The measurement results of electrical characteristics demonstrate that it is ohm electrical contact behavior between the nano-material and micro-electrodes in the proposed device which also have the field effect. The proposed 1D nano-material-based device shows the application potential in the sensing fields.

Superconducting properties of Nb-Cu nano-composites and nano-alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parab, Pradnya, E-mail: pradnyaprb@gmail.com; Kumar, Sanjeev; Bhui, Prabhjyot

The evolution of the superconducting transition temperature (T{sub c}) in nano-composite and nano-alloys of Nb-Cu, grown by DC magnetron co-sputtering are investigated. Microstructure of these films depends less strongly on the ratio of Nb:Cu but more on the growth temperature. At higher growth temperature, phase separated granular films of Nb and Cu were formed which showed superconducting transition temperatures (T{sub c}) of ~ 7.2±0.5 K, irrespective of the composition. Our results show that this is primarily influenced by the microstructure of the films determined during growth which rules out the superconducting proximity effect expected in these systems. At room temperaturemore » growth, films with nano-scale alloying were obtained at the optimal compositional range of 45-70 atomic% (At%) of Nb. These were also superconducting with a T{sub c} of 3.2 K.« less

Some Characteristics of Free Cell Population in the Airways of Rats after Intratracheal Instillation of Copper-Containing Nano-Scale Particles

PubMed Central

Privalova, Larisa I.; Katsnelson, Boris A.; Loginova, Nadezhda V.; Gurvich, Vladimir B.; Shur, Vladimir Y.; Beikin, Yakov B.; Sutunkova, Marina P.; Minigalieva, Ilzira A.; Shishkina, Ekaterina V.; Pichugova, Svetlana V.; Tulakina, Ludmila G.; Beljayeva, Svetlana V.

2014-01-01

We used stable water suspensions of copper oxide particles with mean diameter 20 nm and of particles containing copper oxide and element copper with mean diameter 340 nm to assess the pulmonary phagocytosis response of rats to a single intratracheal instillation of these suspensions using optical, transmission electron, and semi-contact atomic force microscopy and biochemical indices measured in the bronchoalveolar lavage fluid. Although both nano and submicron ultrafine particles were adversely bioactive, the former were found to be more toxic for lungs as compared with the latter while evoking more pronounced defense recruitment of alveolar macrophages and especially of neutrophil leukocytes and more active phagocytosis. Based on our results and literature data, we consider both copper solubilization and direct contact with cellular organelles (mainly, mitochondria) of persistent particles internalized by phagocytes as probable mechanisms of their cytotoxicity. PMID:25421246

MicroTribological Performance of Au-MoS2 and Ti-MoS2 Coatings with Varying Contact Pressure

DTIC Science & Technology

2011-02-15

Dvorak, S.D., Wahl, K.J., Singer, I.L.: In situ analysis of third body contributions to sliding friction of a Pb-Mo-S coating in dry and humid air...University, Montreal. QC H3A 2B2, Canada e-mail: richard.chromik@mcgill.ca J. R. Lince Tribology Section, Spacecraft Materials Laboratory, The Aerospace...than a decade, the testing of nano- and micro-scale sliding contacts has been an important research area that seeks to improve the tribological

Improved light extraction efficiency in GaN-based light emitting diode by nano-scale roughening of p-GaN surface.

PubMed

Park, Sang Jae; Sadasivam, Karthikeyan Giri; Chung, Tae Hoon; Hong, Gi Cheol; Kim, Jin Bong; Kim, Sang Mook; Park, Si-Hyun; Jeon, Seong-Ran; Lee, June Key

2008-10-01

Improvement in light extraction efficiency of Ultra Violet-Light Emitting Diode (UV-LED) is achieved by nano-scale roughening of p-type Gallium Nitride (p-GaN) surface. The process of surface roughening is carried out by using self assembled gold (Au) nano-clusters with support of nano-size silicon-oxide (SiO2) pillars on p-GaN surface as a dry etching mask and by p-GaN regrowth in the regions not covered by the mask after dry etching. Au nano-clusters are formed by rapid thermal annealing (RTA) process carried out at 600 degrees C for 1 min using 15 nm thick Au layer on top of SiO2. The p-GaN roughness is controlled by p-GaN regrowth time. Four different time values of 15 sec, 30 sec, 60 sec and 120 sec are considered for p-GaN regrowth. Among the four different p-GaN regrowth time values 30 sec regrown p-GaN sample has the optimum roughness to increase the electroluminescence (EL) intensity to a value approximately 60% higher than the EL intensity of a conventional LED.

Experimental study on the flow/ heat transfer performance of micro-scale pin fin coating with super-hydrophobic surface adding Nano particle

NASA Astrophysics Data System (ADS)

Hua, Junye; Duan, Yuanyuan; Li, Gui; Xu, Qiong; Li, Dong; Wu, Wei; Zhao, Xiaobao; Qiu, Delai

2018-02-01

The experimental studies on heat transfer and flow resistance characteristics of ellipse-shape micro pin fin have been conducted which is drafted with hydrophobic material, holding the various contact angles fulfilled by adjusting the amount of Nano particle. The results show that with the increases of contact angle(83°,99.5°, 119.5°and 151.5°), the bottom wall temperature rises under the same flow rate. Under a certain heating condition with heating power as 100 W, the average convective heat transfer coefficient decreases with the increase of contact angle with the same Re. The value of Nu for ellipse-shape micro pin fin increases with a higher Re, with the maximum value under experimental condition of Nu as 25. Besides, the friction coefficient of micro pin fin experimental section drafted hydrophobicity treatment significantly decreases, compared with the smooth micro pin fin experimental section (θ = 83°). While the higher contact angle has obvious positive influences on friction coefficient under the same Re. Generally, the flow resistance performance of ellipse-shape micro pin fin drafted with hydrophobic material is better than that without any treatment.

Low-temperature method of producing nano-scaled graphene platelets and their nanocomposites

DOEpatents

Zhamu, Aruna [Centerville, OH; Shi, Jinjun [Columbus, OH; Guo, Jiusheng [Centerville, OH; Jang, Bor Z [Centerville, OH

2012-03-13

A method of exfoliating a layered material to produce separated nano-scaled platelets having a thickness smaller than 100 nm. The method comprises: (a) providing a graphite intercalation compound comprising a layered graphite containing expandable species residing in an interlayer space of the layered graphite; (b) exposing the graphite intercalation compound to an exfoliation temperature lower than 650.degree. C. for a duration of time sufficient to at least partially exfoliate the layered graphite without incurring a significant level of oxidation; and (c) subjecting the at least partially exfoliated graphite to a mechanical shearing treatment to produce separated platelets. The method can further include a step of dispersing the platelets in a polymer or monomer solution or suspension as a precursor step to nanocomposite fabrication.

Evaporation characteristics of thin film liquid argon in nano-scale confinement: A molecular dynamics study

NASA Astrophysics Data System (ADS)

Hasan, Mohammad Nasim; Shavik, Sheikh Mohammad; Rabbi, Kazi Fazle; Haque, Mominul

2016-07-01

Molecular dynamics simulation has been carried out to explore the evaporation characteristics of thin liquid argon film in nano-scale confinement. The present study has been conducted to realize the nano-scale physics of simultaneous evaporation and condensation inside a confined space for a three phase system with particular emphasis on the effect of surface wetting conditions. The simulation domain consisted of two parallel platinum plates; one at the top and another at the bottom. The fluid comprised of liquid argon film at the bottom plate and vapor argon in between liquid argon and upper plate of the domain. Considering hydrophilic and hydrophobic nature of top and bottom surfaces, two different cases have been investigated: (i) Case A: Both top and bottom surfaces are hydrophilic, (ii) Case B: both top and bottom surfaces are hydrophobic. For all cases, equilibrium molecular dynamics (EMD) was performed to reach equilibrium state at 90 K. Then the lower wall was set to four different temperatures such as 110 K, 120 K, 130 K and 140 K to perform non-equilibrium molecular dynamics (NEMD). The variation of temperature and density as well as the variation of system pressure with respect to time were closely monitored for each case. The heat fluxes normal to top and bottom walls were estimated and discussed to illuminate the effectiveness of heat transfer in both hydrophilic and hydrophobic confinement at various boundary temperatures of the bottom plate.

Optical and electrical properties of GaN-based light emitting diodes grown on micro- and nano-scale patterned Si substrate

NASA Astrophysics Data System (ADS)

Chiu, Ching-Hsueh; Lin, Chien-Chung; Deng, Dongmei; Kuo, Hao-Chung; Lau, Kei-May

2011-10-01

We investigate the optical and electrical characteristics of the GaN-based light emitting diodes (LEDs) grown on Micro and Nano-scale Patterned silicon substrate (MPLEDs and NPLEDs). The transmission electron microscopy (TEM) images reveal the suppression of threading dislocation density in InGaN/GaN structure on nano-pattern substrate due to nanoscale epitaxial lateral overgrowth (NELOG). The plan-view and cross-section cathodoluminescence (CL) mappings show less defective and more homogeneous active quantum well region growth on nano-porous substrates. From temperature dependent photoluminescence (PL) and low temperature time-resolved photoluminescence (TRPL) measurement, NPLEDs has better carrier confinement and higher radiative recombination rate than MPLEDs. In terms of device performance, NPLEDs exhibits smaller electroluminescence (EL) peak wavelength blue shift, lower reverse leakage current and decreases efficiency droop compared with the MPLEDs. These results suggest the feasibility of using NPSi for the growth of high quality and power LEDs on Si substrates.

Fracture behavior of nano-scale rubber-modified epoxies

NASA Astrophysics Data System (ADS)

Bacigalupo, Lauren N.

The primary focus of the first portion of this study is to compare physical and mechanical properties of a model epoxy that has been toughened with one of three different types of rubber-based modifier: a traditional telechelic oligomer (phase separates into micro-size particles), a core-shell latex particle (preformed nano-scale particles) and a triblock copolymer (self-assembles into nano-scale particles). The effect of modifier content on the physical properties of the matrix was determined using several thermal analysis methods, which provided insight into any inherent alterations of the epoxy matrix. Although the primary objective is to study the role of particle size on the fracture toughness, stiffness and strength were also determined since these properties are often reduced in rubber-toughened epoxies. It was found that since the CSR- and SBM-modified epoxies are composed of less rubber, thermal and mechanical properties of the epoxy were better maintained. In order to better understand the fracture behavior and mechanisms of the three types of rubber particles utilized in this study, extensive microscopy analysis was conducted. Scanning transmission electron microscopy (STEM) was used to quantify the volume fraction of particles, transmission optical microscopy (TOM) was used to determine plastic damage zone size, and scanning electron microscopy (SEM) was used to assess void growth in the plastic zone after fracture. By quantifying these characteristics, it was then possible to model the plastic damage zone size as well as the fracture toughness to elucidate the behavior of the rubber-modified epoxies. It was found that localized shear yielding and matrix void growth are the active toughening mechanisms in all rubber-modified epoxies in this study, however, matrix void growth was more prevalent. The second portion of this study investigated the use of three acrylate-based triblocks and four acrylate-based diblocks to modify a model epoxy system. By

Inverted Silicon Nanopencil Array Solar Cells with Enhanced Contact Structures.

PubMed

Liang, Xiaoguang; Shu, Lei; Lin, Hao; Fang, Ming; Zhang, Heng; Dong, Guofa; Yip, SenPo; Xiu, Fei; Ho, Johnny C

2016-09-27

Although three-dimensional nanostructured solar cells have attracted extensive research attention due to their superior broadband and omnidirectional light-harvesting properties, majority of them are still suffered from complicated fabrication processes as well as disappointed photovoltaic performances. Here, we employed our newly-developed, low-cost and simple wet anisotropic etching to fabricate hierarchical silicon nanostructured arrays with different solar cell contact design, followed by systematic investigations of their photovoltaic characteristics. Specifically, nano-arrays with the tapered tips (e.g. inverted nanopencils) are found to enable the more conformal top electrode deposition directly onto the nanostructures for better series and shunt conductance, but its insufficient film coverage at the basal plane would still restrict the charge carrier collection. In contrast, the low-platform contact design facilitates a substantial photovoltaic device performance enhancement of ~24%, as compared to the one of conventional top electrode design, due to the shortened current path and improved lateral conductance for the minimized carrier recombination and series resistance. This enhanced contact structure can not only maintain excellent photon-trapping behaviors of nanostructures, but also help to eliminate adverse impacts of these tapered nano-morphological features on the contact resistance, providing further insight into design consideration in optimizing the contact geometry for high-performance nanostructured photovoltaic devices.

Inverted Silicon Nanopencil Array Solar Cells with Enhanced Contact Structures

PubMed Central

Liang, Xiaoguang; Shu, Lei; Lin, Hao; Fang, Ming; Zhang, Heng; Dong, Guofa; Yip, SenPo; Xiu, Fei; Ho, Johnny C.

2016-01-01

Although three-dimensional nanostructured solar cells have attracted extensive research attention due to their superior broadband and omnidirectional light-harvesting properties, majority of them are still suffered from complicated fabrication processes as well as disappointed photovoltaic performances. Here, we employed our newly-developed, low-cost and simple wet anisotropic etching to fabricate hierarchical silicon nanostructured arrays with different solar cell contact design, followed by systematic investigations of their photovoltaic characteristics. Specifically, nano-arrays with the tapered tips (e.g. inverted nanopencils) are found to enable the more conformal top electrode deposition directly onto the nanostructures for better series and shunt conductance, but its insufficient film coverage at the basal plane would still restrict the charge carrier collection. In contrast, the low-platform contact design facilitates a substantial photovoltaic device performance enhancement of ~24%, as compared to the one of conventional top electrode design, due to the shortened current path and improved lateral conductance for the minimized carrier recombination and series resistance. This enhanced contact structure can not only maintain excellent photon-trapping behaviors of nanostructures, but also help to eliminate adverse impacts of these tapered nano-morphological features on the contact resistance, providing further insight into design consideration in optimizing the contact geometry for high-performance nanostructured photovoltaic devices. PMID:27671709

Kinetic research on dechlorinating dichlorobenzene in aqueous system by nano-scale nickel/iron loaded with CMC/NFC hydrogel.

PubMed

Wan, Xiao-Fang; Guo, Congbao; Liu, Yu; Chai, Xin-Sheng; Li, Youming; Chen, Guangxue

2018-03-01

In this study, we reported on the nano-scale nickel/iron particles loaded in carboxymethyl/nanofibrillated cellulose (CMC/NFC) hydrogel for the dechlorination of o-dichlorobenzene (DCB) in aqueous solution. The biodegradable hydrogel may provide an ideal supporting material for fastening the bimetallic nano-scale particles, which was examined and characterized by TEM, SEM-EDX, FT-IR and BET. The performance of the selected bimetallic particles was evaluated by conducting the dechlorination of DCB in the solution under different reaction conditions (e.g., pH, dosage of nickel/iron nanoparticles and temperature). The results showed that about 70% of DCB could be dechlorinated at 20 °C in 8 h, which indicated that the immobilized reactive material had a high reduction activity when Ni/Fe loading dosage in the hydrogel (18 wt%) was considered. Moreover, the reduction behavior agreed to the pseudo-first order reaction, in which the dechlorination rate was irrelative to the pH aqueous solution. A kinetic model for predicting the concentration of DCB during the reduction reaction was established based on the experimental data. Copyright © 2017 Elsevier Ltd. All rights reserved.

The intermembrane space domain of Tim23 is intrinsically disordered with a distinct binding region for presequences

PubMed Central

de la Cruz, Laura; Bajaj, Rakhi; Becker, Stefan; Zweckstetter, Markus

2010-01-01

Proteins targeted to the mitochondrial matrix are translocated through the outer and the inner mitochondrial membranes by two protein complexes, the translocase of the outer membrane (TOM) and one of the translocases of the inner membrane (TIM23). The protein Tim23, the core component of TIM23, consists of an N-terminal, soluble domain in the intermembrane space (IMS) and a C-terminal domain that forms the import pore across the inner membrane. Before translocation proceeds, precursor proteins are recognized by the N-terminal domain of Tim23, Tim23N (residues 1–96). By using NMR spectroscopy, we show that Tim23N is a monomeric protein belonging to the family of intrinsically disordered proteins. Titrations of Tim23N with two presequences revealed a distinct binding region of Tim23N formed by residues 71–84. In a charge-hydropathy plot containing all soluble domains of TOM and TIM23, Tim23N was found to be the only domain with more than 40 residues in the IMS that is predicted to be intrinsically disordered, suggesting that Tim23N might function as hub in the mitochondrial import machinery protein network. PMID:20718036

Scaling for quantum tunneling current in nano- and subnano-scale plasmonic junctions

PubMed Central

Zhang, Peng

2015-01-01

When two conductors are separated by a sufficiently thin insulator, electrical current can flow between them by quantum tunneling. This paper presents a self-consistent model of tunneling current in a nano- and subnano-meter metal-insulator-metal plasmonic junction, by including the effects of space charge and exchange correlation potential. It is found that the J-V curve of the junction may be divided into three regimes: direct tunneling, field emission, and space-charge-limited regime. In general, the space charge inside the insulator reduces current transfer across the junction, whereas the exchange-correlation potential promotes current transfer. It is shown that these effects may modify the current density by orders of magnitude from the widely used Simmons’ formula, which is only accurate for a limited parameter space (insulator thickness > 1 nm and barrier height > 3 eV) in the direct tunneling regime. The proposed self-consistent model may provide a more accurate evaluation of the tunneling current in the other regimes. The effects of anode emission and material properties (i.e. work function of the electrodes, electron affinity and permittivity of the insulator) are examined in detail in various regimes. Our simple model and the general scaling for tunneling current may provide insights to new regimes of quantum plasmonics. PMID:25988951

The intermembrane space protein Erv1 of Trypanosoma brucei is essential for mitochondrial Fe-S cluster assembly and operates alone.

PubMed

Haindrich, Alexander C; Boudová, Michala; Vancová, Marie; Diaz, Priscila Peña; Horáková, Eva; Lukeš, Julius

2017-06-01

Sulfhydryl oxidase Erv1 is a ubiquitous and conserved protein of the mitochondrial intermembrane space that plays a role in the transport of small sulfur-containing proteins. In higher eukaryotes, Erv1 interacts with the mitochondrial import protein Mia40. However, Trypanosoma brucei lacks an obvious Mia40 homologue in its genome. Here we show by tandem affinity purification and mass spectrometry that in this excavate protist, Erv1 functions without a Mia40 homologue and most likely any other interaction partner. Down-regulation of TbErv1 caused a reduction of the mitochondrial membrane potential already within 24h to less than 50% when compared with control cells. The depletion of TbErv1 was accompanied by accumulation of trCOIV precursor, with a concomitant reduction of aconitase activity both in the cytosol and mitochondrion. Overall, TbErv1 seems to have a role in the mitochondrial translocation and Fe-S cluster assembly in the organelle. Copyright © 2017 Elsevier B.V. All rights reserved.

Evaluation of dose dependent antimicrobial activity of self-assembled chitosan, nano silver and chitosan-nano silver composite against several pathogens.

PubMed

Tareq, Foysal Kabir; Fayzunnesa, Mst; Kabir, Md Shahariar; Nuzat, Musrat

2018-01-01

The aim of this investigation to preparation of silver nanoparticles organized chitosan nano polymer, which effective against microbial and pathogens, when apply to liquid medium and edible food products surface, will rescue the growth of microbes. Self-assembly approach used to synthesis of silver nanoparticles and silver nanoparticles organized chitosan nano polymer. Silver nanoparticles and silver nanoparticles organized chitosan nano polymer and film characterized using Ultra-violate visible spectrometer (UV-vis), X-ray diffraction (X-ray), and Scanning electronic microscope (SEM). The crystalline structured protein capped nano silver successfully synthesized at range of 12 nm-29 nm and organized into chitosan nano polymer. Antimicrobial ingredient in liquid medium and food product surface provide to rescue oxidative change and growth of microorganism to provide higher safety. The silver nanoparticles organized chitosan nano polymer caused the death of microorganism. The materials in nano scale synthesized successfully using self-assembly method, which showed good antimicrobial properties. Copyright © 2017 Elsevier Ltd. All rights reserved.

Simultaneous droplet impingement dynamics and heat transfer on nano-structured surfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shen, Jian; Graber, Christof; Liburdy, James

This study examines the hydrodynamics and temperature characteristics of distilled deionized water droplets impinging on smooth and nano-structured surfaces using high speed (HS) and infrared (IR) imaging at We = 23.6 and Re = 1593, both based on initial drop impingement parameters. Results for a smooth and nano-structured surface for a range of surface temperatures are compared. Droplet impact velocity, transient spreading diameter and dynamic contact angle are measured. The near surface average droplet fluid temperatures are evaluated for conditions of evaporative cooling and boiling. Also included are surface temperature results using a gold layered IR opaque surface on silicon.more » Four stages of the impingement process are identified: impact, boiling, near constant surface diameter evaporation, and final dry-out. For the boiling conditions there is initial nucleation followed by severe boiling, then near constant diameter evaporation resulting in shrinking of the droplet height. When a critical contact angle is reached during evaporation the droplet rapidly retracts to a smaller diameter reducing the contact area with the surface. This continues as a sequence of retractions until final dry out. The basic trends are the same for all surfaces, but the nano-structured surface has a lower dissipated energy during impact and enhances the heat transfer for evaporative cooling with a 20% shorter time to achieve final dry out. (author)« less

Mitochondrial cardiolipin/phospholipid trafficking: the role of membrane contact site complexes and lipid transfer proteins.

PubMed

Schlattner, Uwe; Tokarska-Schlattner, Malgorzata; Rousseau, Denis; Boissan, Mathieu; Mannella, Carmen; Epand, Richard; Lacombe, Marie-Lise

2014-04-01

Historically, cellular trafficking of lipids has received much less attention than protein trafficking, mostly because its biological importance was underestimated, involved sorting and translocation mechanisms were not known, and analytical tools were limiting. This has changed during the last decade, and we discuss here some progress made in respect to mitochondria and the trafficking of phospholipids, in particular cardiolipin. Different membrane contact site or junction complexes and putative lipid transfer proteins for intra- and intermembrane lipid translocation have been described, involving mitochondrial inner and outer membrane, and the adjacent membranes of the endoplasmic reticulum. An image emerges how cardiolipin precursors, remodeling intermediates, mature cardiolipin and its oxidation products could migrate between membranes, and how this trafficking is involved in cardiolipin biosynthesis and cell signaling events. Particular emphasis in this review is given to mitochondrial nucleoside diphosphate kinase D and mitochondrial creatine kinases, which emerge to have roles in both, membrane junction formation and lipid transfer. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Contact formation and patterning approaches for group-III nitride light emitters

NASA Astrophysics Data System (ADS)

Hou, Wenting

Solid state lighting via light emitting diodes (LEDs) and laser diodes (LDs) is a rapidly progressing technology with the potential to greatly exceed the efficiency of traditional lighting systems. This dissertation focuses on the development of electrical contacts and patterning schemes for highly efficient green LEDs and LD structures. Efficiency of LEDs can be greatly improved by means of nano-patterning processes. LEDs grown on nano-imprint patterned sapphire substrates showed promising performance, with improvement in both internal quantum efficiency and light extraction efficiency. As an alternative to nano-imprint lithography, this study utilized a simple method to generate irregular nano-patterns by a Ni self-assembly process and applied the process to both sapphire substrate and n-GaN template. In both approaches, the nano-patterned LEDs showed an improvement in light output power. For the device fabrication of LEDs and LDs, low-resistance ohmic contacts are essential for high efficiency. In search of a highly transparent ohmic contact to p-type GaN, I analyzed various metal/indium-tin-oxide (ITO) (Ag/ITO, AgCu/ITO, Ni/ITO, and NiZn/ITO) contact schemes and compared them with Ni/Au, NiZn/Ag, and ITO contacts. For ITO-based contacts, the inserted metal layer can boost conductivity while the ITO thickness can be optimized for constructive transmission interference on GaN exceeding the extraction from bare GaN. The best compromise was obtained for an Ag/ITO (3 nm /67 nm) ohmic contact, with a relative transmittance of 97% of the bare GaN near 530 nm, and a specific contact resistance of 3x10-2 O·cm 2. The contact proved particularly suitable for green light emitting diodes in epi-up geometry. Graphene as another alternative transparent p-contact was also evaluated. Furthermore, this dissertation offered a pre-deposition treatment to contact schemes on undoped and n-doped GaN, rendering a standard post-deposition annealing step unnecessary. As-deposited Ti

Effects of glucose concentration on osteogenic differentiation of type II diabetes mellitus rat bone marrow-derived mesenchymal stromal cells on a nano-scale modified titanium.

PubMed

Yamawaki, I; Taguchi, Y; Komasa, S; Tanaka, A; Umeda, M

2017-08-01

Diabetes mellitus (DM) is a common disease worldwide. Patients with DM have an increased risk of losing their teeth compared with other individuals. Dental implants are a standard of care for treating partial or full edentulism, and various implant surface treatments have recently been developed to increase dental implant stability. However, some studies have reported that DM reduces osseointegration and the success rate of dental implants. The purpose of this study was to determine the effects of high glucose levels for hard tissue formation on a nano-scale modified titanium surface. Titanium disks were heated at 600°C for 1 h after treatment with or without 10 m NaOH solution. All disks were incubated with type II DM rat bone marrow-derived mesenchymal stromal cells before exposure to one of four concentrations of glucose (5.5, 8.0, 12.0 or 24.0 mm). The effect of different glucose concentrations on bone marrow-derived mesenchymal stromal cell osteogenesis and inflammatory cytokines on the nano-scale modified titanium surface was evaluated. Alkaline phosphatase activity decreased with increasing glucose concentration. In contrast, osteocalcin production and calcium deposition were significantly decreased at 8.0 mm glucose, but increased with glucose concentrations over 8.0 mm. Differences in calcium/phosphate ratio associated with the various glucose concentrations were similar to osteocalcin production and calcium deposition. Inflammatory cytokines were expressed at high glucose concentrations, but the nano-scale modified titanium surface inhibited the effect of high glucose concentrations. High glucose concentration increased hard tissue formation, but the quality of the mineralized tissue decreased. Furthermore, the nano-scale modified titanium surface increased mineralized tissue formation and anti-inflammation, but the quality of hard tissue was dependent on glucose concentration. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Nano-technology and nano-toxicology.

PubMed

Maynard, Robert L

2012-01-01

Rapid developments in nano-technology are likely to confer significant benefits on mankind. But, as with perhaps all new technologies, these benefits are likely to be accompanied by risks, perhaps by new risks. Nano-toxicology is developing in parallel with nano-technology and seeks to define the hazards and risks associated with nano-materials: only when risks have been identified they can be controlled. This article discusses the reasons for concern about the potential effects on health of exposure to nano-materials and relates these to the evidence of the effects on health of the ambient aerosol. A number of hypotheses are proposed and the dangers of adopting unsubstantiated hypotheses are stressed. Nano-toxicology presents many challenges and will need substantial financial support if it is to develop at a rate sufficient to cope with developments in nano-technology.

Nano-technology and nano-toxicology

PubMed Central

Maynard, Robert L.

2012-01-01

Rapid developments in nano-technology are likely to confer significant benefits on mankind. But, as with perhaps all new technologies, these benefits are likely to be accompanied by risks, perhaps by new risks. Nano-toxicology is developing in parallel with nano-technology and seeks to define the hazards and risks associated with nano-materials: only when risks have been identified they can be controlled. This article discusses the reasons for concern about the potential effects on health of exposure to nano-materials and relates these to the evidence of the effects on health of the ambient aerosol. A number of hypotheses are proposed and the dangers of adopting unsubstantiated hypotheses are stressed. Nano-toxicology presents many challenges and will need substantial financial support if it is to develop at a rate sufficient to cope with developments in nano-technology. PMID:22662021

Design of a Small-Scale Multi-Inlet Vortex Mixer for Scalable Nanoparticle Production and Application to the Encapsulation of Biologics by Inverse Flash NanoPrecipitation.

PubMed

Markwalter, Chester E; Prud'homme, Robert K

2018-05-14

Flash NanoPrecipitation (FNP) is a scalable approach to generate polymeric nanoparticles using rapid micromixing in specially-designed geometries such as a confined impinging jets (CIJ) mixer or a Multi-Inlet Vortex Mixer (MIVM). A major limitation of formulation screening using the MIVM is that a single run requires tens of milligrams of the therapeutic. To overcome this, we have developed a scaled-down version of the MIVM, requiring as little as 0.2 mg of therapeutic, for formulation screening. The redesigned mixer can then be attached to pumps for scale-up of the identified formulation. It was shown that Reynolds Number allowed accurate scaling between the two MIVM designs. The utility of the small-scale MIVM for formulation development was demonstrated through the encapsulation of a number of hydrophilic macromolecules using inverse Flash NanoPrecipitation with target loadings as high as 50% by mass. Copyright © 2018. Published by Elsevier Inc.

A novel diamond micro-/nano-machining process for the generation of hierarchical micro-/nano-structures

NASA Astrophysics Data System (ADS)

Zhu, Zhiwei; To, Suet; Ehmann, Kornel F.; Xiao, Gaobo; Zhu, Wule

2016-03-01

A new mechanical micro-/nano-machining process that combines rotary spatial vibrations (RSV) of a diamond tool and the servo motions of the workpiece is proposed and applied for the generation of multi-tier hierarchical micro-/nano-structures. In the proposed micro-/nano-machining system, the servo motion, as the primary cutting motion generated by a slow-tool-servo, is adopted for the fine generation of the primary surfaces with complex shapes. The RSV, as the tertiary cutting operation, is superimposed on the secondary fundamental rotary cutting motion to construct secondary nano-structures on the primary surface. Since the RSV system generally works at much higher frequencies and motion resolution than the primary and secondary motions, it leads to an inherent hierarchical cutting architecture. To investigate the machining performance, complex micro-/nano-structures were generated and explored by both numerical simulations and actual cutting tests. Rotary vibrations of the diamond tool at a constant rotational distance offer an inherent constant cutting velocity, leading to the ability for the generation of homogeneous micro-/nano-structures with fixed amplitudes and frequencies of the vibrations, even over large-scale surfaces. Furthermore, by deliberately combining the non-resonant three-axial vibrations and the servo motion, the generation of a variety of micro-/nano-structures with complex shapes and with flexibly tunable feature sizes can be achieved.

Nano-TiO2, ultrasound and sequential nano-TiO2/ultrasonic degradation of N-acetyl-para-aminophenol from aqueous solution.

PubMed

Ayanda, Olushola S; Nelana, Simphiwe M; Petrik, Leslie F; Naidoo, Eliazer B

2017-10-01

The application of nano-TiO 2 as adsorbent combined with ultrasound for the degradation of N-acetyl-para-aminophenol (AAP) from aqueous solution was investigated. The nano-TiO 2 was characterized by means of powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), and attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR). Experimental results revealed that the adsorption of AAP by nano-TiO 2 fitted the pseudo-second-order kinetic model, the equilibrium could be explained by the Freundlich isotherm and the treatment process is exothermic. The optimum removal efficiency of AAP (128.89 mg/g (77.33%)) was achieved at pH 4 when 0.03 g of nano-TiO 2 was mixed with 50 mL of 100 mg/L AAP aqueous solution at ambient temperature, 60 min contact time, and a stirring speed of 120 rpm. Ultrasound at 20 kHz and pH 3 was favorable and it resulted in 52.61% and 57.43% removal efficiency with and without the addition of nano-TiO 2 , respectively. The degradation of AAP by ultrasound followed by nano-TiO 2 treatment resulted in approximately 99.50% removal efficiency. This study showed that a sequential ultrasound and nano-TiO 2 treatment process could be employed for the removal of AAP or other emerging water and wastewater contaminants.

Wettability of nano-epoxies to UHMWPE fibers.

PubMed

Neema, S; Salehi-Khojin, A; Zhamu, A; Zhong, W H; Jana, S; Gan, Y X

2006-07-01

Ultra high molecular weight polyethylene (UHMWPE) fibers have a unique combination of outstanding mechanical, physical, and chemical properties. However, as reinforcements for manufacturing high performance composite materials, UHMWPE fibers have poor wettability with most polymers. As a result, the interfacial bonding strength between the fibers and polymer matrices is very low. Recently, developing so-called nano-matrices containing reactive graphitic nanofibers (r-GNFs) has been proposed to promote the wetting of such matrices to certain types of fiber reinforcements. In this work, the wettability of UHMWPE fibers with different epoxy matrices including a nano-epoxy, and a pure epoxy was investigated. Systematic experimental work was conducted to determine the viscosity of the epoxies, the contact angle between the epoxies and the fibers. Also obtained are the surface energy of the fibers and the epoxies. The experimental results show that the wettability of the UHMWPE fibers with the nano-epoxy is much better than that of the UHMWPE fibers with the pure epoxy.

Endoplasmic reticulum-plasma membrane contact sites integrate sterol and phospholipid regulation.

PubMed

Quon, Evan; Sere, Yves Y; Chauhan, Neha; Johansen, Jesper; Sullivan, David P; Dittman, Jeremy S; Rice, William J; Chan, Robin B; Di Paolo, Gilbert; Beh, Christopher T; Menon, Anant K

2018-05-01

Tether proteins attach the endoplasmic reticulum (ER) to other cellular membranes, thereby creating contact sites that are proposed to form platforms for regulating lipid homeostasis and facilitating non-vesicular lipid exchange. Sterols are synthesized in the ER and transported by non-vesicular mechanisms to the plasma membrane (PM), where they represent almost half of all PM lipids and contribute critically to the barrier function of the PM. To determine whether contact sites are important for both sterol exchange between the ER and PM and intermembrane regulation of lipid metabolism, we generated Δ-super-tether (Δ-s-tether) yeast cells that lack six previously identified tethering proteins (yeast extended synatotagmin [E-Syt], vesicle-associated membrane protein [VAMP]-associated protein [VAP], and TMEM16-anoctamin homologues) as well as the presumptive tether Ice2. Despite the lack of ER-PM contacts in these cells, ER-PM sterol exchange is robust, indicating that the sterol transport machinery is either absent from or not uniquely located at contact sites. Unexpectedly, we found that the transport of exogenously supplied sterol to the ER occurs more slowly in Δ-s-tether cells than in wild-type (WT) cells. We pinpointed this defect to changes in sterol organization and transbilayer movement within the PM bilayer caused by phospholipid dysregulation, evinced by changes in the abundance and organization of PM lipids. Indeed, deletion of either OSH4, which encodes a sterol/phosphatidylinositol-4-phosphate (PI4P) exchange protein, or SAC1, which encodes a PI4P phosphatase, caused synthetic lethality in Δ-s-tether cells due to disruptions in redundant PI4P and phospholipid regulatory pathways. The growth defect of Δ-s-tether cells was rescued with an artificial "ER-PM staple," a tether assembled from unrelated non-yeast protein domains, indicating that endogenous tether proteins have nonspecific bridging functions. Finally, we discovered that sterols play a role

Fabrication of large-area nano-scale patterned sapphire substrate with laser interference lithography

NASA Astrophysics Data System (ADS)

Xuan, Ming-dong; Dai, Long-gui; Jia, Hai-qiang; Chen, Hong

2014-01-01

Periodic triangle truncated pyramid arrays are successfully fabricated on the sapphire substrate by a low-cost and high-efficiency laser interference lithography (LIL) system. Through the combination of dry etching and wet etching techniques, the nano-scale patterned sapphire substrate (NPSS) with uniform size is prepared. The period of the patterns is 460 nm as designed to match the wavelength of blue light emitting diode (LED). By improving the stability of the LIL system and optimizing the process parameters, well-defined triangle truncated pyramid arrays can be achieved on the sapphire substrate with diameter of 50.8 mm. The deviation of the bottom width of the triangle truncated pyramid arrays is 6.8%, which is close to the industrial production level of 3%.

Software Architecture for a Virtual Environment for Nano Scale Assembly (VENSA).

PubMed

Lee, Yong-Gu; Lyons, Kevin W; Feng, Shaw C

2004-01-01

A Virtual Environment (VE) uses multiple computer-generated media to let a user experience situations that are temporally and spatially prohibiting. The information flow between the user and the VE is bidirectional and the user can influence the environment. The software development of a VE requires orchestrating multiple peripherals and computers in a synchronized way in real time. Although a multitude of useful software components for VEs exists, many of these are packaged within a complex framework and can not be used separately. In this paper, an architecture is presented which is designed to let multiple frameworks work together while being shielded from the application program. This architecture, which is called the Virtual Environment for Nano Scale Assembly (VENSA), has been constructed for interfacing with an optical tweezers instrument for nanotechnology development. However, this approach can be generalized for most virtual environments. Through the use of VENSA, the programmer can rely on existing solutions and concentrate more on the application software design.

Nano-scale hydrogen-bond network improves the durability of greener cements

PubMed Central

Jacobsen, Johan; Rodrigues, Michelle Santos; Telling, Mark T. F.; Beraldo, Antonio Ludovico; Santos, Sérgio Francisco; Aldridge, Laurence P.; Bordallo, Heloisa N.

2013-01-01

More than ever before, the world's increasing need for new infrastructure demands the construction of efficient, sustainable and durable buildings, requiring minimal climate-changing gas-generation in their production. Maintenance-free “greener” building materials made from blended cements have advantages over ordinary Portland cements, as they are cheaper, generate less carbon dioxide and are more durable. The key for the improved performance of blends (which substitute fine amorphous silicates for cement) is related to their resistance to water penetration. The mechanism of this water resistance is of great environmental and economical impact but is not yet understood due to the complexity of the cement's hydration reactions. Using neutron spectroscopy, we studied a blend where cement was replaced by ash from sugar cane residuals originating from agricultural waste. Our findings demonstrate that the development of a distinctive hydrogen bond network at the nano-scale is the key to the performance of these greener materials. PMID:24036676

Software Architecture for a Virtual Environment for Nano Scale Assembly (VENSA)

PubMed Central

Lee, Yong-Gu; Lyons, Kevin W.; Feng, Shaw C.

2004-01-01

A Virtual Environment (VE) uses multiple computer-generated media to let a user experience situations that are temporally and spatially prohibiting. The information flow between the user and the VE is bidirectional and the user can influence the environment. The software development of a VE requires orchestrating multiple peripherals and computers in a synchronized way in real time. Although a multitude of useful software components for VEs exists, many of these are packaged within a complex framework and can not be used separately. In this paper, an architecture is presented which is designed to let multiple frameworks work together while being shielded from the application program. This architecture, which is called the Virtual Environment for Nano Scale Assembly (VENSA), has been constructed for interfacing with an optical tweezers instrument for nanotechnology development. However, this approach can be generalized for most virtual environments. Through the use of VENSA, the programmer can rely on existing solutions and concentrate more on the application software design. PMID:27366610

Ecological assessment of nano-enabled supercapacitors for automotive applications

NASA Astrophysics Data System (ADS)

Weil, M.; Dura, H.; Shimon, B.; Baumann, M.; Zimmermann, B.; Ziemann, S.; Lei, C.; Markoulidis, F.; Lekakou, T.; Decker, M.

2012-09-01

New materials on nano scale have the potential to overcome existing technical barriers and are one of the most promising key technologies to enable the decoupling of economic growth and resource consumption. Developing these innovative materials for industrial applications means facing a complex quality profile, which includes among others technical, economic, and ecological aspects. So far the two latter aspects are not sufficiently included in technology development, especially from a life cycle point of view. Supercapacitors are considered a promising option for electric energy storage in hybrid and full electric cars. In comparison with presently used lithium based electro chemical storage systems supercapacitors possess a high specific power, but a relatively low specific energy. Therefore, the goal of ongoing research is to develop a new generation of supercapacitors with high specific power and high specific energy. To reach this goal particularly nano materials are developed and tested on cell level. In the presented study the ecological implications (regarding known environmental effects) of carbon based nano materials are analysed using Life Cycle Assessment (LCA). Major attention is paid to efficiency gains of nano particle production due to scaling up of such processes from laboratory to industrial production scales. Furthermore, a developed approach will be displayed, how to assess the environmental impact of nano materials on an automotive system level over the whole life cycle.

Nucleate boiling performance on nano/microstructures with different wetting surfaces

PubMed Central

2012-01-01

A study of nucleate boiling phenomena on nano/microstructures is a very basic and useful study with a view to the potential application of modified surfaces as heating surfaces in a number of fields. We present a detailed study of boiling experiments on fabricated nano/microstructured surfaces used as heating surfaces under atmospheric conditions, employing identical nanostructures with two different wettabilities (silicon-oxidized and Teflon-coated). Consequently, enhancements of both boiling heat transfer (BHT) and critical heat flux (CHF) are demonstrated in the nano/microstructures, independent of their wettability. However, the increment of BHT and CHF on each of the different wetting surfaces depended on the wetting characteristics of heating surfaces. The effect of water penetration in the surface structures by capillary phenomena is suggested as a plausible mechanism for the enhanced CHF on the nano/microstructures regardless of the wettability of the surfaces in atmospheric condition. This is supported by comparing bubble shapes generated in actual boiling experiments and dynamic contact angles under atmospheric conditions on Teflon-coated nano/microstructured surfaces. PMID:22559173

Impact of incomplete metal coverage on the electrical properties of metal-CNT contacts: A large-scale ab initio study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fediai, Artem, E-mail: artem.fediai@nano.tu-dresden.de; Ryndyk, Dmitry A.; Center for Advancing Electronics Dresden, TU Dresden, 01062 Dresden

2016-09-05

Using a dedicated combination of the non-equilibrium Green function formalism and large-scale density functional theory calculations, we investigated how incomplete metal coverage influences two of the most important electrical properties of carbon nanotube (CNT)-based transistors: contact resistance and its scaling with contact length, and maximum current. These quantities have been derived from parameter-free simulations of atomic systems that are as close as possible to experimental geometries. Physical mechanisms that govern these dependences have been identified for various metals, representing different CNT-metal interaction strengths from chemisorption to physisorption. Our results pave the way for an application-oriented design of CNT-metal contacts.

Stability of retained austenite in high carbon steel under compressive stress: an investigation from macro to nano scale

PubMed Central

Hossain, R.; Pahlevani, F.; Quadir, M. Z.; Sahajwalla, V.

2016-01-01

Although high carbon martensitic steels are well known for their industrial utility in high abrasion and extreme operating environments, due to their hardness and strength, the compressive stability of their retained austenite, and the implications for the steels’ performance and potential uses, is not well understood. This article describes the first investigation at both the macro and nano scale of the compressive stability of retained austenite in high carbon martensitic steel. Using a combination of standard compression testing, X-ray diffraction, optical microstructure, electron backscattering diffraction imaging, electron probe micro-analysis, nano-indentation and micro-indentation measurements, we determined the mechanical stability of retained austenite and martensite in high carbon steel under compressive stress and identified the phase transformation mechanism, from the macro to the nano level. We found at the early stage of plastic deformation hexagonal close-packed (HCP) martensite formation dominates, while higher compression loads trigger body-centred tetragonal (BCT) martensite formation. The combination of this phase transformation and strain hardening led to an increase in the hardness of high carbon steel of around 30%. This comprehensive characterisation of stress induced phase transformation could enable the precise control of the microstructures of high carbon martensitic steels, and hence their properties. PMID:27725722

Novel nano-semiconductor film layer supported nano-Pd Complex Nanostructured Catalyst Pd/Ⓕ-MeOx/AC for High Efficient Selective Hydrogenation of Phenol to Cyclohexanone.

PubMed

Si, Jiaqi; Ouyang, Wenbing; Zhang, Yanji; Xu, Wentao; Zhou, Jicheng

2017-04-28

Supported metal as a type of heterogeneous catalysts are the most widely used in industrial processes. High dispersion of the metal particles of supported catalyst is a key factor in determining the performance of such catalysts. Here we report a novel catalyst Pd/Ⓕ-MeO x /AC with complex nanostructured, Pd nanoparticles supported on the platelike nano-semiconductor film/activated carbon, prepared by the photocatalytic reduction method, which exhibited high efficient catalytic performance for selective hydrogenation of phenol to cyclohexanone. Conversion of phenol achieved up to more than 99% with a lower mole ratio (0.5%) of active components Pd and phenol within 2 h at 70 °C. The synergistic effect of metal nanoparticles and nano-semiconductors support layer and the greatly increasing of contact interface of nano-metal-semiconductors may be responsible for the high efficiency. This work provides a clear demonstration that complex nanostructured catalysts with nano-metal and nano-semiconductor film layer supported on high specific surface AC can yield enhanced catalytic activity and can afford promising approach for developing new supported catalyst.

Point contact tunneling spectroscopy apparatus for large scale mapping of surface superconducting properties

DOE PAGES

Groll, Nickolas; Pellin, Michael J.; Zasadzinksi, John F.; ...

2015-09-18

In this paper, we describe the design and testing of a point contact tunneling spectroscopy device that can measure material surface superconducting properties (i.e., the superconducting gap Δ and the critical temperature T C) and density of states over large surface areas with size up to mm 2. The tip lateral (X,Y) motion, mounted on a (X,Y,Z) piezo-stage, was calibrated on a patterned substrate consisting of Nb lines sputtered on a gold film using both normal (Al) and superconducting (PbSn) tips at 1.5 K. The tip vertical (Z) motion control enables some adjustment of the tip-sample junction resistance that canmore » be measured over 7 orders of magnitudes from a quasi-ohmic regime (few hundred Ω) to the tunnel regime (from tens of kΩ up to few GΩ). The low noise electronic and LabVIEW program interface are also presented. Finally, the point contact regime and the large-scale motion capabilities are of particular interest for mapping and testing the superconducting properties of macroscopic scale superconductor-based devices.« less

Design and fabrication of highly hydrophobic Mn nano-sculptured thin films and evaluation of surface properties on hydrophobicity

NASA Astrophysics Data System (ADS)

Hosseini, Somaye; Savaloni, Hadi; Gholipour-Shahraki, Mehran

2017-03-01

The wettability of solid surfaces is important from the aspects of both science and technology. The Mn nano-sculptured thin films were designed and fabricated by oblique angle deposition of Mn on glass substrates at room temperature. The obtained structure was characterized by field emission scanning electron microscopy and atomic force microscopy. The wettability of thin films samples was investigated by water contact angle (WCA). The 4-pointed helical star-shaped structure exhibits hydrophobicity with static WCAs of more than 133° for a 10-mg distilled water droplet. This sample also shows the rose petal effect with the additional property of high adhesion. The Mn nano-sculptured thin films also act as a sticky surface which is confirmed by hysteresis of the contact angle obtained from advancing and receding contact angles measurements. Physicochemical property of liquid phase could effectively change the contact angle, and polar solvents in contact with hydrophobic solid surfaces do not necessarily show high contact angle value.

Oscillation-based methods for actuation and manipulation of nano-objects

NASA Astrophysics Data System (ADS)

Popov, V. L.

2017-09-01

We discuss how oscillations can be used for fixation or manipulation of nano-objects or producing nano-drives. The underlying principles are scale-invariant and principally can be scaled down up to the molecular scale. The main underlying principle of fixation and actuation occurs to be symmetry breaking of an oscillating system. From this unifying standpoint, a series of actuation principles are discussed as dragging, ratchets, micro walking, friction-inertia actuators, oscillation tweezers, flagella motors for propulsion in liquids as well as some recently proposed actuation principles.

Nano-viscosity of supercooled liquid measured by fluorescence correlation spectroscopy: Pressure and temperature dependence and the density scaling

NASA Astrophysics Data System (ADS)

Meier, G.; Gapinski, J.; Ratajczyk, M.; Lettinga, M. P.; Hirtz, K.; Banachowicz, E.; Patkowski, A.

2018-03-01

The Stokes-Einstein relation allows us to calculate apparent viscosity experienced by tracers in complex media on the basis of measured self-diffusion coefficients. Such defined nano-viscosity values can be obtained through single particle techniques, like fluorescence correlation spectroscopy (FCS) and particle tracking (PT). In order to perform such measurements, as functions of pressure and temperature, a new sample cell was designed and is described in this work. We show that this cell in combination with a long working distance objective of the confocal microscope can be used for successful FCS, PT, and confocal imaging experiments in broad pressure (0.1-100 MPa) and temperature ranges. The temperature and pressure dependent nano-viscosity of a van der Waals liquid obtained from the translational diffusion coefficient measured in this cell by means of FCS obeys the same scaling as the rotational relaxation and macro-viscosity of the system.

Recent advances in micro-scale and nano-scale high-performance liquid-phase chromatography for proteome research.

PubMed

Tao, Dingyin; Zhang, Lihua; Shan, Yichu; Liang, Zhen; Zhang, Yukui

2011-01-01

High-performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI-MS-MS) is regarded as one of the most powerful techniques for separation and identification of proteins. Recently, much effort has been made to improve the separation capacity, detection sensitivity, and analysis throughput of micro- and nano-HPLC, by increasing column length, reducing column internal diameter, and using integrated techniques. Development of HPLC columns has also been rapid, as a result of the use of submicrometer packing materials and monolithic columns. All these innovations result in clearly improved performance of micro- and nano-HPLC for proteome research.

Micro/nano-computed tomography technology for quantitative dynamic, multi-scale imaging of morphogenesis.

PubMed

Gregg, Chelsea L; Recknagel, Andrew K; Butcher, Jonathan T

2015-01-01

Tissue morphogenesis and embryonic development are dynamic events challenging to quantify, especially considering the intricate events that happen simultaneously in different locations and time. Micro- and more recently nano-computed tomography (micro/nanoCT) has been used for the past 15 years to characterize large 3D fields of tortuous geometries at high spatial resolution. We and others have advanced micro/nanoCT imaging strategies for quantifying tissue- and organ-level fate changes throughout morphogenesis. Exogenous soft tissue contrast media enables visualization of vascular lumens and tissues via extravasation. Furthermore, the emergence of antigen-specific tissue contrast enables direct quantitative visualization of protein and mRNA expression. Micro-CT X-ray doses appear to be non-embryotoxic, enabling longitudinal imaging studies in live embryos. In this chapter we present established soft tissue contrast protocols for obtaining high-quality micro/nanoCT images and the image processing techniques useful for quantifying anatomical and physiological information from the data sets.

Modeling and analysis of sub-surface leakage current in nano-MOSFET under cutoff regime

NASA Astrophysics Data System (ADS)

Swami, Yashu; Rai, Sanjeev

2017-02-01

The high leakage current in nano-meter regimes is becoming a significant portion of power dissipation in nano-MOSFET circuits as threshold voltage, channel length, and gate oxide thickness are scaled down to nano-meter range. Precise leakage current valuation and meticulous modeling of the same at nano-meter technology scale is an increasingly a critical work in designing the low power nano-MOSFET circuits. We present a specific compact model for sub-threshold regime leakage current in bulk driven nano-MOSFETs. The proposed logical model is instigated and executed into the latest updated PTM bulk nano-MOSFET model and is found to be in decent accord with technology-CAD simulation data. This paper also reviews various transistor intrinsic leakage mechanisms for nano-MOSFET exclusively in weak inversion, like drain-induced barricade lowering (DIBL), gate-induced drain leakage (GIDL), gate oxide tunneling (GOT) leakage etc. The root cause of the sub-surface leakage current is mainly due to the nano-scale short channel length causing source-drain coupling even in sub-threshold domain. Consequences leading to carriers triumphing the barricade between the source and drain. The enhanced model effectively considers the following parameter dependence in the account for better-quality value-added results like drain-to-source bias (VDS), gate-to-source bias (VGS), channel length (LG), source/drain junction depth (Xj), bulk doping concentration (NBULK), and operating temperature (Top).

Plastic deformation and failure mechanisms in nano-scale notched metallic glass specimens under tensile loading

NASA Astrophysics Data System (ADS)

Dutta, Tanmay; Chauniyal, Ashish; Singh, I.; Narasimhan, R.; Thamburaja, P.; Ramamurty, U.

2018-02-01

In this work, numerical simulations using molecular dynamics and non-local plasticity based finite element analysis are carried out on tensile loading of nano-scale double edge notched metallic glass specimens. The effect of acuteness of notches as well as the metallic glass chemical composition or internal material length scale on the plastic deformation response of the specimens are studied. Both MD and FE simulations, in spite of the fundamental differences in their nature, indicate near-identical deformation features. Results show two distinct transitions in the notch tip deformation behavior as the acuity is increased, first from single shear band dominant plastic flow localization to ligament necking, and then to double shear banding in notches that are very sharp. Specimens with moderately blunt notches and composition showing wider shear bands or higher material length scale characterizing the interaction stress associated with flow defects display profuse plastic deformation and failure by ligament necking. These results are rationalized from the role of the interaction stress and development of the notch root plastic zones.

Nano-TiO₂--feasibility and challenges for human health risk assessment based on open literature.

PubMed

Christensen, Frans M; Johnston, Helinor J; Stone, Vicki; Aitken, Robert J; Hankin, Steve; Peters, Sheona; Aschberger, Karin

2011-06-01

This study aims at investigating feasibility and challenges associated with conducting a human health risk assessment for nano-titanium-dioxide (nano-TiO₂) based on the open literature by following an approach similar to a classical regulatory risk assessment. Gaps in the available data set, both in relation to exposures and hazard, do not allow reaching any definite conclusions that could be used for regulatory decision-making. Results show that repeated inhalation in the workplace and possibly consumer inhalation may cause risks. Also short-term inhalation following spray applications may cause risks. Main future work should focus on generating occupational and consumer inhalation exposure data, as well as toxicity data on absorption following inhalation, repeated dermal contact, and contact with damaged skin. Also relevant seems further information on possible neurotoxicity and genotoxicity/carcinogenicity, as well as establishing a No Observed Adverse Effect Level (NOAEL) for acute inhalation of nano-TiO₂.

Ab-initio simulations on adhesion and material transfer between contacting Al and TiN surfaces

NASA Astrophysics Data System (ADS)

Feldbauer, Gregor; Wolloch, Michael; Mohn, Peter; Redinger, Josef; Vernes, Andras

2014-03-01

Contacts of surfaces at the atomic scale are crucial in many modern applications from analytical techniques like indentation or AFM experiments to technologies such as nano- and micro-electro-mechanical-systems (N-/M-EMS). Furthermore, detailed insights into such contacts are fundamental for a better understanding of tribological processes like wear. A series of simulations is performed within the framework of Density Functional Theory (DFT) to investigate the approaching, contact and subsequent separation of two atomically flat surfaces consisting of different materials. Aluminum (Al) and titanium-nitride (TiN) slabs have been chosen as a model system representing the interaction between a soft and a hard material. The approaching and separation is simulated by moving one slab in discrete steps and allowing for electronic and ionic relaxations after each one. The simulations reveal the influences of different surface orientations ((001), (011), (111)) and alignments of the surfaces with respect to each other on the adhesion, equilibrium distance, charge distribution and material transfer between the surfaces. Material transfer is observed for configurations where the interface is stronger than the softer material.

Micro/nano-particles and Cells: Manipulation, Transport, and Self-assembly

DTIC Science & Technology

2014-10-23

SECURITY CLASSIFICATION OF: Technologies that control nano- and micron- sized inert as well as biological materials are crucial to realizing engineered...that control nano- and micron- sized inert as well as biological materials are crucial to realizing engineered systems that can assemble, transport, and...nano-scale particles offer several advantages as building blocks of artificial materials . The relative ease of modifying their charge states

Proposal for New Experimental Tests of the Bose-Einstein Condensation Mechanism for Low-Energy Nuclear Reaction and Transmutation Processes in Deuterium Loaded - and Nano-Scale Cavities

NASA Astrophysics Data System (ADS)

Kim, Yeong E.; Koltick, David S.; Reifenberger, Ronald G.; Zubarev, Alexander L.

2006-02-01

Most of experimental results of low-energy nuclear reaction (LENR) reported so far cannot be reproduced on demand. There have been persistent experimental results indicating that the LENR and transmutation processes in condensed matters (LENRTPCM) are surface phenomena rather than bulk phenomena. Recently proposed Bose-Einstein condensation (BEC) mechanism may provide a suitable theoretical description of the surface phenomena. New experiments are proposed and described for testing the BEC mechanism for LENR and transmutation processes in micro- and nano-scale traps. (1) We propose the use of micro- or nano-porous conducting materials as a cathode in electrolysis experiments with heavy water with or without Li in order to stabilize the active surface spots and to enhance the effect for the purpose of improving the reproducibility of excess heat generation and nuclear emission. (2) We propose new experimental tests of the BEC mechanism by measuring the pressure and temperature dependence of LENR events using deuterium gas and these deuterated metals with or without Li. If the LENRTPCM are surface phenomena, the proposed use of micro-/nano-scale porous materials is expected to enhance and scale up the LENRTPCM effects by many order of magnitude, and thus may lead to better reproductivity and theoretical understanding of the phenomena.

Reverse micelle-loaded lipid nano-emulsions: new technology for nano-encapsulation of hydrophilic materials.

PubMed

Anton, Nicolas; Mojzisova, Halina; Porcher, Emilien; Benoit, Jean-Pierre; Saulnier, Patrick

2010-10-15

This study presents novel, recently patented technology for encapsulating hydrophilic species in lipid nano-emulsions. The method is based on the phase-inversion temperature method (the so-called PIT method), which follows a low-energy and solvent-free process. The nano-emulsions formed are stable for months, and exhibit droplet sizes ranging from 10 to 200 nm. Hydrophilic model molecules of fluorescein sodium salt are encapsulated in the oily core of these nano-emulsion droplets through their solubilisation in the reverse micellar system. As a result, original, multi-scaled nano-objects are generated with a 'hydrophilic molecule in a reverse-micelles-in-oil-in-water' structure. Once fluorescein has been encapsulated it remains stable, for thermodynamic reasons, and the encapsulation yields can reach 90%. The reason why such complex objects can be formed is due to the soft method used (PIT method) which allows the conservation of the structure of the reverse micelles throughout the formulation process, up to their entrapment in the nano-emulsion droplets. In this study, we focus the investigation on the process itself, revealing its potential and limits. Since the formulation of nanocarriers for the encapsulation of hydrophilic substances still remains a challenge, this study may constitute a significant advance in this field. Copyright 2010 Elsevier B.V. All rights reserved.

Integrated Surface and Mechanical Characterization of Freestanding Biological and Other Nano-Structures Using Atomic Force Microscopy

NASA Astrophysics Data System (ADS)

Wang, Xin

This dissertation is focused on surface and mechanical characterization of freestanding biological and other nano-structures using atomic force microscopy including two parts: cell mechanics and nano-structure mechanics. The main purpose of this work is to investigate how the nano- / micro-scale mechanical properties affect macro-scale function. In cancer cells, efficacy of drug delivery is oftentimes declined due to the thick dendritic network of oligosaccharide mucin chains on the cell surface. AFM is used to measure the force needed to pierce the mucin layer to reach the cell surface. A pool of ovarian, pancreatic, lung, colorectal and breast cancer cells are characterized. The studies offer additional support for the development of clinical and pharmaceutical approaches to combat mucin over-expression in tumors during cancer chemotherapy. Macroscopic adhesion-aggregation and subsequent transportation of microorganisms in porous medium are closely related to the microscopic deformation and adhesion mechanical properties. The classical Tabor's parameter is modified. Multiple bacterial strains are characterized in terms of aggregates size, aggregation index and transportation kinetics. AFM is employed to obtain the microscopic coupled adhesion-deformation properties. The strong correlation between Tabor's parameter and aggregation-deposition-transportation suggests the AFM characterization is capable of making reliable predication of macroscopic behavior. A novel "nano-cheese-cutter" is fabricated on tipless AFM cantilever to measure elastic modulus and interfacial adhesion of a 1-D freestanding nano-structure. A single electrospun fiber is attached to the free end of AFM cantilever, while another fiber is similarly prepared on a mica substrate in an orthogonal direction. An external load is applied to deform the two fibers into complementary V-shapes. This work is extended to investigate the interfacial adhesion energy between dissimilar materials. SWCNT thin

Import, maturation, and function of SOD1 and its copper chaperone CCS in the mitochondrial intermembrane space.

PubMed

Kawamata, Hibiki; Manfredi, Giovanni

2010-11-01

Cu, Zn, superoxide dismutase (SOD1) is a ubiquitous enzyme localized in multiple cellular compartments, including mitochondria, where it concentrates in the intermembrane space (IMS). Similar to other small IMS proteins, the import and retention of SOD1 in the IMS is linked to its folding and maturation, involving the formation of critical intra- and intermolecular disulfide bonds. Therefore, the cysteine residues of SOD1 play a fundamental role in its IMS localization. IMS import of SOD1 involves its copper chaperone, CCS, whose mitochondrial distribution is regulated by the Mia40/Erv1 disulfide relay system in a redox-dependent manner: CCS promotes SOD1 maturation and retention in the IMS. The function of SOD1 in the IMS is still unknown, but it is plausible that it serves to remove superoxide released from the mitochondrial respiratory chain. Mutations in SOD1 cause familial amyotrophic lateral sclerosis (ALS), whose pathologic features include mitochondrial bioenergetic dysfunction. Mutant SOD1 localization in the IMS is not dictated by oxygen concentration and the Mia40/Erv1 system, but is primarily dependent on aberrant protein folding and aggregation. Mutant SOD1 localization and aggregation in the IMS might cause the mitochondrial abnormalities observed in familial ALS and could play a significant role in disease pathogenesis.

Measuring contact area in a sliding human finger-pad contact.

PubMed

Liu, X; Carré, M J; Zhang, Q; Lu, Z; Matcher, S J; Lewis, R

2018-02-01

The work outlined in this paper was aimed at achieving further understanding of skin frictional behaviour by investigating the contact area between human finger-pads and flat surfaces. Both the static and the dynamic contact areas (in macro- and micro-scales) were measured using various techniques, including ink printing, optical coherence tomography (OCT) and Digital Image Correlation (DIC). In the studies of the static measurements using ink printing, the experimental results showed that the apparent and the real contact area increased with load following a piecewise linear correlation function for a finger-pad in contact with paper sheets. Comparisons indicated that the OCT method is a reliable and effective method to investigate the real contact area of a finger-pad and allow micro-scale analysis. The apparent contact area (from the DIC measurements) was found to reduce with time in the transition from the static phase to the dynamic phase while the real area of contact (from OCT) increased. The results from this study enable the interaction between finger-pads and contact object surface to be better analysed, and hence improve the understanding of skin friction. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Hybrid Plasmonic Microring Nano-Ruler.

PubMed

Du, Jing; Wang, Jian

2018-06-15

Surface plasmonic polariton (SPP) has attracted increasing interest for its ability of confining light in the subwavelength scale and breaking the diffraction limit. Recently, there have appeared several important developments of SPP applied in plasmon rulers, waveguides and resonators. By combing these concepts we present a novel hybrid plasmonic microring nano-ruler relying on the sensitive hybrid mode property and the microring resonator structure. The designed nano-ruler can measure distance in nanoscale resolution and offer adjustable sensitivity, which exceeds 14.8 as the distance is less than 5 nm by recording the transmission spectra and outstrips 200 dB/nm by observing the shift of output intensity. These demonstrations suggest that hybrid plasmonic microring nano-ruler could be a promising candidate enabling high-resoluation measurement.

Nature-replicated nano-in-micro structures for triboelectric energy harvesting.

PubMed

Seol, Myeong-Lok; Woo, Jong-Ho; Lee, Dong-Il; Im, Hwon; Hur, Jae; Choi, Yang-Kyu

2014-10-15

Triboelectric nanogenerators with nature-replicated interface structures are presented. Effective contact areas of the triboelectric surfaces are largely enhanced because of the densely packed nano-in-micro hierarchical structures in nature. The enlarged contact area causes stronger triboelectric charge density, which results in output power increment. The interface engineering also allows the improved humidity resistance, which is an important parameter for the stable energy harvesting. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Field-Induced Crystalline-to-Amorphous Phase Transformation on the Si Nano-Apex and the Achieving of Highly Reliable Si Nano-Cathodes

PubMed Central

Huang, Yifeng; Deng, Zexiang; Wang, Weiliang; Liang, Chaolun; She, Juncong; Deng, Shaozhi; Xu, Ningsheng

2015-01-01

Nano-scale vacuum channel transistors possess merits of higher cutoff frequency and greater gain power as compared with the conventional solid-state transistors. The improvement in cathode reliability is one of the major challenges to obtain high performance vacuum channel transistors. We report the experimental findings and the physical insight into the field induced crystalline-to-amorphous phase transformation on the surface of the Si nano-cathode. The crystalline Si tip apex deformed to amorphous structure at a low macroscopic field (0.6~1.65 V/nm) with an ultra-low emission current (1~10 pA). First-principle calculation suggests that the strong electrostatic force exerting on the electrons in the surface lattices would take the account for the field-induced atomic migration that result in an amorphization. The arsenic-dopant in the Si surface lattice would increase the inner stress as well as the electron density, leading to a lower amorphization field. Highly reliable Si nano-cathodes were obtained by employing diamond like carbon coating to enhance the electron emission and thus decrease the surface charge accumulation. The findings are crucial for developing highly reliable Si-based nano-scale vacuum channel transistors and have the significance for future Si nano-electronic devices with narrow separation. PMID:25994377

Uniting Superhydrophobic, Superoleophobic and Lubricant Infused Slippery Behavior on Copper Oxide Nano-structured Substrates

NASA Astrophysics Data System (ADS)

Ujjain, Sanjeev Kumar; Roy, Pritam Kumar; Kumar, Sumana; Singha, Subhash; Khare, Krishnacharya

2016-10-01

Alloys, specifically steel, are considered as the workhorse of our society and are inimitable engineering materials in the field of infrastructure, industry and possesses significant applications in our daily life. However, creating a robust synthetic metallic surface that repels various liquids has remained extremely challenging. The wettability of a solid surface is known to be governed by its geometric nano-/micro structure and the chemical composition. Here, we are demonstrating a facile and economical way to generate copper oxide micro-nano structures with spherical (0D), needle (1D) and hierarchical cauliflower (3D) morphologies on galvanized steel substrates using a simple chemical bath deposition method. These nano/micro textured steel surfaces, on subsequent coating of a low surface energy material display excellent superhydrophobic, superoleophobic and slippery behavior. Polydimethylsiloxane coated textured surfaces illustrate superhydrophobicity with water contact angle about 160°(2) and critical sliding angle ~2°. When functionalized with low-surface energy perfluoroalkylsilane, these surfaces display high repellency for low surface tension oils as well as hydrocarbons. Among them, the hierarchical cauliflower morphology exhibits re-entrant structure thereby showing the best superoleophobicity with contact angle 149° for dodecane. Once infused with a lubricant like silicone oil, they show excellent slippery behavior with low contact angle hysteresis (~ 2°) for water drops.

Picosecond laser micro/nano surface texturing of nickel for superhydrophobicity

NASA Astrophysics Data System (ADS)

Wang, X. C.; Wang, B.; Xie, H.; Zheng, H. Y.; Lam, Y. C.

2018-03-01

A single step direct picosecond laser texturing process was demonstrated to be able to obtain a superhydrophobic surface on a nickel substrate, a key material for mold fabrication in the manufacture of various devices, including polymeric microfluidic devices. A two-scale hierarchical surface structure of regular 2D array micro-bumps with nano-ripples was produced on a nickel surface. The laser textured surface initially showed superhydrophilicity with almost complete wetting of the structured surface just after laser treatment, then quickly changed to nearly superhydrophobic with a water contact angle (WCA) of 140° in less than 1 d, and finally became superhydrophobic with a WCA of more than 150° and a contact angle hysteresis (CAH) of less than 5°. The mechanism involved in the process is discussed in terms of surface morphology and surface chemistry. The ultra-fast laser induced NiO catalytic effect was thought to play a key role in modifying the surface chemistry so as to lower the surface energy. The developed process has the potential to improve the performance of nickel mold in the fabrication of microfluidic devices.

Micro- and Nano-Scale Fabrication of Fluorinated Polymers by Direct Etching Using Focused Ion Beam

NASA Astrophysics Data System (ADS)

Fukutake, Naoyuki; Miyoshi, Nozomi; Takasawa, Yuya; Urakawa, Tatsuya; Gowa, Tomoko; Okamoto, Kazumasa; Oshima, Akihiro; Tagawa, Seiichi; Washio, Masakazu

2010-06-01

Micro- and nano-scale fabrications of various fluorinated polymers were demonstrated by direct maskless etching using a focused ion beam (FIB). The etching rates of perfluorinated polymers, such as poly(tetrafluoroethylene) (PTFE), poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP), poly(tetrafluoroethylene-co-perfluoroalkoxyvinylether) (PFA), were about 500-1000 times higher than those of partially fluorinated polymers, such as poly(tetrafluoroethylene-co-ethylene) (ETFE) and poly(vinilydene-fluoride) (PVdF). Controlled high quality and high aspect-ratio nanostructures of spin-coated cross-linked PTFE were obtained without solid debris. The height and diameter of the fibers were about 1.5 µm and 90 nm, respectively. Their aspect ratio was about 17.

Micro- and Nano-Scale Fabrication of Fluorinated Polymers by Direct Etching Using Focused Ion Beam

NASA Astrophysics Data System (ADS)

Naoyuki Fukutake,; Nozomi Miyoshi,; Yuya Takasawa,; Tatsuya Urakawa,; Tomoko Gowa,; Kazumasa Okamoto,; Akihiro Oshima,; Seiichi Tagawa,; Masakazu Washio,

2010-06-01

Micro- and nano-scale fabrications of various fluorinated polymers were demonstrated by direct maskless etching using a focused ion beam (FIB). The etching rates of perfluorinated polymers, such as poly(tetrafluoroethylene) (PTFE), poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP), poly(tetrafluoroethylene-co-perfluoroalkoxyvinylether) (PFA), were about 500-1000 times higher than those of partially fluorinated polymers, such as poly(tetrafluoroethylene-co-ethylene) (ETFE) and poly(vinilydene-fluoride) (PVdF). Controlled high quality and high aspect-ratio nanostructures of spin-coated cross-linked PTFE were obtained without solid debris. The height and diameter of the fibers were about 1.5 μm and 90 nm, respectively. Their aspect ratio was about 17.

Nano-structured surface plasmon resonance sensor for sensitivity enhancement

NASA Astrophysics Data System (ADS)

Kim, Jae-Ho; Kim, Hyo-Sop; Kim, Jin-Ho; Choi, Sung-Wook; Cho, Yong-Jin

2008-08-01

A new nano-structured SPR sensor was devised to improve its sensitivity. Nano-scaled silica particles were used as the template to fabricate nano-structure. The surface of the silica particles was modified with thiol group and a single layer of the modified silica particles was attached on the gold or silver thin film using Langmuir-Blodgett (LB) method. Thereafter, gold or silver was coated on the template by an e-beam evaporator. Finally, the nano-structured surface with basin-like shape was obtained after removing the silica particles by sonication. Applying the new developed SPR sensor to a model food of alcoholic beverage, the sensitivities for the gold and silver nano-structured sensors, respectively, had 95% and 126% higher than the conventional one.

From micro- to nano-scale molding of metals : size effect during molding of single crystal Al with rectangular strip punches.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, K.; Meng, W. J.; Mei, F.

2011-02-01

A single crystal Al specimen was molded at room temperature with long, rectangular, strip diamond punches. Quantitative molding response curves were obtained at a series of punch widths, ranging from 5 {micro}m to 550 nm. A significant size effect was observed, manifesting itself in terms of significantly increasing characteristic molding pressure as the punch width decreases to 1.5 {micro}m and below. A detailed comparison of the present strip punch molding results was made with Berkovich pyramidal indentation on the same single crystal Al specimen. The comparison reveals distinctly different dependence of the characteristic pressure on corresponding characteristic length. The presentmore » results show the feasibility of micro-/nano-scale compression molding as a micro-/nano-fabrication technique, and offer an experimental test case for size-dependent plasticity theories.« less

Fabrication and condensation characteristics of metallic superhydrophobic surface with hierarchical micro-nano structures

NASA Astrophysics Data System (ADS)

Chu, Fuqiang; Wu, Xiaomin

2016-05-01

Metallic superhydrophobic surfaces have various applications in aerospace, refrigeration and other engineering fields due to their excellent water repellent characteristics. This study considers a simple but widely applicable fabrication method using a two simultaneous chemical reactions method to prepare the acid-salt mixed solutions to process the metal surfaces with surface deposition and surface etching to construct hierarchical micro-nano structures on the surface and then modify the surface with low surface-energy materials. Al-based and Cu-based superhydrophobic surfaces were fabricated using this method. The Al-based superhydrophobic surface had a water contact angle of 164° with hierarchical micro-nano structures similar to the lotus leaves. The Cu-based surface had a water contact angle of 157° with moss-like hierarchical micro-nano structures. Droplet condensation experiments were also performed on these two superhydrophobic surfaces to investigate their condensation characteristics. The results show that the Al-based superhydrophobic surface has lower droplet density, higher droplet jumping probability, slower droplet growth rate and lower surface coverage due to the more structured hierarchical structures.

Integration of micro-/nano-/quantum-scale photonic devices: scientific and technological considerations

NASA Astrophysics Data System (ADS)

Lee, El-Hang; Lee, Seung-Gol; O, Beom Hoan; Park, Se Geun

2004-08-01

Scientific and technological issues and considerations regarding the integration of miniaturized microphotonic devices, circuits and systems in micron, submicron, and quantum scale, are presented. First, we examine the issues regarding the miniaturization of photonic devices including the size effect, proximity effect, energy confinement effect, microcavity effect, optical and quantum interference effect, high field effect, nonlinear effect, noise effect, quantum optical effect, and chaotic effect. Secondly, we examine the issues regarding the interconnection including the optical alignment, minimizing the interconnection losses, and maintaining optical modes. Thirdly, we address the issues regarding the two-dimensional or three-dimensional integration either in a hybrid format or in a monolithic format between active devices and passive devices of varying functions. We find that the concept of optical printed circuit board (O-PCB) that we propose is highly attractive as a platform for micro/nano/quantum-scale photonic integration. We examine the technological issues to be addressed in the process of fabrication, characterization, and packaging for actual implementation of the miniaturization, interconnection and integration. Devices that we have used for our study include: mode conversion schemes, micro-ring and micro-racetrack resonator devices, multimode interference devices, lasers, vertical cavity surface emitting microlasers, and their arrays. Future prospects are also discussed.

Nano-LISA for in vitro diagnostic applications

NASA Astrophysics Data System (ADS)

Maswadi, Saher; Glickman, Randolph D.; Elliott, Rowe; Barsalou, Norman

2011-03-01

We previously reported the detection of bacterial antigen with immunoaffinity reactions using laser optoacoustic spectroscopy and antibody-coupled gold nanorods (Ab-NR) as a contrast agent specifically targeted to the antigen of interest. The Nano-LISA (Nanoparticle Linked Immunosorbent Assay) method has been adapted to detect three very common blood-borne viral infectious agents, i.e. human T-lymphotropic virus (HTLV), human immunodeficiency virus (HIV) and hepatitis-B (Hep-B). These agents were used in a model test panel to illustrate the performance of the Nano-LISA technique. A working laboratory prototype of a Nano-LISA microplate reader-sensor was assembled and tested against the panel containing specific antigens of each of the infectious viral agents. Optoacoustic (OA) responses generated by the samples were detected using the probe beam deflection technique, an all-optical, non-contact technique. A LabView graphical user interface was developed for control of the instrument and real-time display of the test results. The detection limit of Nano-LISA is at least 1 ng/ml of viral antigen, and can reach 10 pg/ml, depending on the binding affinity of the specific detection antibody used to synthesize the Ab-NR. The method has sufficient specificity, i.e. the detection reagents do not cross-react with noncomplementary antigens. Thus, the OA microplate reader, incorporating NanoLISA, has adequate detection sensitivity and specificity for use in clinical in vitro diagnostic testing.

Dynamic contact network between ribosomal subunits enables rapid large-scale rotation during spontaneous translocation

PubMed Central

Bock, Lars V.; Blau, Christian; Vaiana, Andrea C.; Grubmüller, Helmut

2015-01-01

During ribosomal translation, the two ribosomal subunits remain associated through intersubunit bridges, despite rapid large-scale intersubunit rotation. The absence of large barriers hindering rotation is a prerequisite for rapid rotation. Here, we investigate how such a flat free-energy landscape is achieved, in particular considering the large shifts the bridges undergo at the periphery. The dynamics and energetics of the intersubunit contact network are studied using molecular dynamics simulations of the prokaryotic ribosome in intermediate states of spontaneous translocation. Based on observed occupancies of intersubunit contacts, residues were grouped into clusters. In addition to the central contact clusters, peripheral clusters were found to maintain strong steady interactions by changing contacts in the course of rotation. The peripheral B1 bridges are stabilized by a changing contact pattern of charged residues that adapts to the rotational state. In contrast, steady strong interactions of the B4 bridge are ensured by the flexible helix H34 following the movement of protein S15. The tRNAs which span the subunits contribute to the intersubunit binding enthalpy to an almost constant degree, despite their different positions in the ribosome. These mechanisms keep the intersubunit interaction strong and steady during rotation, thereby preventing dissociation and enabling rapid rotation. PMID:26109353

Glutathione redox potential in the mitochondrial intermembrane space is linked to the cytosol and impacts the Mia40 redox state

PubMed Central

Kojer, Kerstin; Bien, Melanie; Gangel, Heike; Morgan, Bruce; Dick, Tobias P; Riemer, Jan

2012-01-01

Glutathione is an important mediator and regulator of cellular redox processes. Detailed knowledge of local glutathione redox potential (EGSH) dynamics is critical to understand the network of redox processes and their influence on cellular function. Using dynamic oxidant recovery assays together with EGSH-specific fluorescent reporters, we investigate the glutathione pools of the cytosol, mitochondrial matrix and intermembrane space (IMS). We demonstrate that the glutathione pools of IMS and cytosol are dynamically interconnected via porins. In contrast, no appreciable communication was observed between the glutathione pools of the IMS and matrix. By modulating redox pathways in the cytosol and IMS, we find that the cytosolic glutathione reductase system is the major determinant of EGSH in the IMS, thus explaining a steady-state EGSH in the IMS which is similar to the cytosol. Moreover, we show that the local EGSH contributes to the partially reduced redox state of the IMS oxidoreductase Mia40 in vivo. Taken together, we provide a comprehensive mechanistic picture of the IMS redox milieu and define the redox influences on Mia40 in living cells. PMID:22705944

Engineering Interfacial Processes at Mini-Micro-Nano Scales Using Sessile Droplet Architecture.

PubMed

Bansal, Lalit; Sanyal, Apratim; Kabi, Prasenjit; Pathak, Binita; Basu, Saptarshi

2018-03-01

Evaporating sessile functional droplets act as the fundamental building block that controls the cumulative outcome of many industrial and biological applications such as surface patterning, 3D printing, photonic crystals, and DNA sequencing, to name a few. Additionally, a drying single sessile droplet forms a high-throughput processing technique using low material volume which is especially suitable for medical diagnosis. A sessile droplet also provides an elementary platform to study and analyze fundamental interfacial processes at various length scales ranging from macroscopically observable wetting and evaporation to microfluidic transport to interparticle forces operating at a nanometric length scale. As an example, to ascertain the quality of 3D printing we must understand the fundamental interfacial processes at the droplet scale. In this article, we review the coupled physics of evaporation flow-contact-line-driven particle transport in sessile colloidal droplets and provide methodologies to control the same. Through natural alterations in droplet vaporization, one can change the evaporative pattern and contact line dynamics leading to internal flow which will modulate the final particle assembly in a nontrivial fashion. We further show that control over particle transport can also be exerted by external stimuli which can be thermal, mechanical oscillations, vapor confinement (walled or a fellow droplet), or chemical (surfactant-induced) in nature. For example, significant augmentation of an otherwise evaporation-driven particle transport in sessile droplets can be brought about simply through controlled interfacial oscillations. The ability to control the final morphologies by manipulating the governing interfacial mechanisms in the precursor stages of droplet drying makes it perfectly suitable for fabrication-, mixing-, and diagnostic-based applications.

Chemically designed Pt/PPy nano-composite for effective LPG gas sensor.

PubMed

Gaikwad, Namrata; Bhanoth, Sreenu; More, Priyesh V; Jain, G H; Khanna, P K

2014-03-07

Simultaneous in situ reduction of hexachloroplatinic acid by the amine group in the pyrrole monomer and oxidation of pyrrole to form polypyrrole (PPy) was examined. The reactions were performed at various temperatures to understand the degree of reduction of platinum precursor as well as doping of polypyrrole with Pt(II) chloro-complex. Spectroscopic images revealed different morphologies for the Pt/PPy nano-composite prepared at various temperatures. The as-prepared Pt/PPy nano-composite samples were tested for their ability to sense liquefied petroleum gas (LPG) which resulted in excellent sensing at relatively low temperature. The porous nature and ohmic contact between the PPy and platinum nanoparticles makes the as-prepared Pt/PPy nano-composite highly useful for sensors as well as electronic applications.

Dynamic and impact contact mechanics of geologic materials: Grain-scale experiments and modeling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cole, David M.; Hopkins, Mark A.; Ketcham, Stephen A.

2013-06-18

High fidelity treatments of the generation and propagation of seismic waves in naturally occurring granular materials is becoming more practical given recent advancements in our ability to model complex particle shapes and their mechanical interaction. Of particular interest are the grain-scale processes that are activated by impact events and the characteristics of force transmission through grain contacts. To address this issue, we have developed a physics based approach that involves laboratory experiments to quantify the dynamic contact and impact behavior of granular materials and incorporation of the observed behavior indiscrete element models. The dynamic experiments do not involve particle damagemore » and emphasis is placed on measured values of contact stiffness and frictional loss. The normal stiffness observed in dynamic contact experiments at low frequencies (e.g., 10 Hz) are shown to be in good agreement with quasistatic experiments on quartz sand. The results of impact experiments - which involve moderate to extensive levels of particle damage - are presented for several types of naturally occurring granular materials (several quartz sands, magnesite and calcium carbonate ooids). Implementation of the experimental findings in discrete element models is discussed and the results of impact simulations involving up to 5 Multiplication-Sign 105 grains are presented.« less

The potential phototoxicity of nano-scale ZnO induced by visible light on freshwater ecosystems.

PubMed

Du, Jingjing; Qv, Mingxiang; Zhang, Yuyan; Yin, Xiaoyun; Wan, Ning; Zhang, Baozhong; Zhang, Hongzhong

2018-06-06

With the development of nanotechnology, nanomaterials have been widely applied in anti-bacterial coating, electronic device, and personal care products. NanoZnO is one of the most used materials and its ecotoxicity has been extensively studied. To explore the potential phototoxicity of nanoZnO induced by visible light, we conducted a long-term experiment on litter decomposition of Typha angustifolia leaves with assessment of fungal multifaceted natures. After 158 d exposure, the decomposition rate of leaf litter was decreased by nanoZnO but no additional effect by visible light. However, visible light enhanced the inhibitory effect of nanoZnO on fungal sporulation rate due to light-induced dissolution of nanoZnO. On the contrary, enzymes such as β-glucosidase, cellobiohydrolase, and leucine-aminopeptidase were significantly increased by the interaction of nanoZnO and visible light, which led to high efficiency of leaf carbon decomposition. Furthermore, different treatments and exposure time separated fungal community associated with litter decomposition. Therefore, the study provided the evidence of the contribution of visible light to nanoparticle phototoxicity at the ecosystem level. Copyright © 2018 Elsevier Ltd. All rights reserved.

Influence of impurities and contact scale on the lubricating properties of bovine submaxillary mucin (BSM) films on a hydrophobic surface.

PubMed

Nikogeorgos, Nikolaos; Madsen, Jan Busk; Lee, Seunghwan

2014-10-01

Lubricating properties of bovine submaxillary mucin (BSM) on a compliant, hydrophobic surface were studied as influenced by impurities, in particular bovine serum albumin (BSA), at macro and nanoscale contacts by means of pin-on-disk tribometry and friction force microscopy (FFM), respectively. At both contact scales, the purity of BSM and the presence of BSA were quantitatively discriminated. The presence of BSA was responsible for higher frictional forces observed from BSM samples containing relatively larger amount of BSA. But, the mechanisms contributing to higher friction forces by BSA were different at different contact scales. At the macroscale contact, higher friction forces were caused by faster and dominant adsorption of BSA into the contacting area under a continuous cycle of desorption and re-adsorption of the macromolecules from tribostress. Nevertheless, all BSMs lowered the interfacial friction forces due to large contact area and a large number of BSM molecules in the contact area. At the nanoscale contact, however, no significant desorption of the macromolecules is expected in tribological contacts because of too small contact area and extremely small number of BSM molecules involved in the contact area. Instead, increasingly higher friction forces with increasing amount of BSA in BSM layer are attributed to higher viscosity caused by BSA in the layer. Comparable size of AFM probes with BSM molecules allowed them to penetrate through the BSM layers and to scratch on the underlying substrates, and thus induced higher friction forces compared to the sliding contact on bare substrates. Copyright © 2014 Elsevier B.V. All rights reserved.

Quantum Control of Light and Matter: From the Macroscopic to the Nano Scale

DTIC Science & Technology

2016-02-02

navigation, and hybrid bio -graphene devices, incorporating enzymes positioned on graphene, for light-driven bio -fuel production with controlled...enzymatic rates. 15. SUBJECT TERMS Light-matter interactions; Quantum control; Slow light; Bose-Einstein condensates; Nano-science; Hybrid bio -nano...precise navigation. They also include hybrid bio -graphene devices incorporating enzymes positioned on graphene for dynamic control of enzymatic

Hierarchical Micro/Nano Structures by Combined Self-Organized Dewetting and Photopatterning of Photoresist Thin Films.

PubMed

Sachan, Priyanka; Kulkarni, Manish; Sharma, Ashutosh

2015-11-17

Photoresists are the materials of choice for micro/nanopatterning and device fabrication but are rarely used as a self-assembly material. We report for the first time a novel interplay of self-assembly and photolithography for fabrication of hierarchical and ordered micro/nano structures. We create self-organized structures by the intensified dewetting of unstable thin (∼10 nm to 1 μm) photoresist films by annealing them in an optimal solvent and nonsolvent liquid mixture that allows spontaneous dewetting to form micro/nano smooth dome-like structures. The density, size (∼100 nm to millimeters), and curvature/contact angle of the dome/droplet structures are controlled by the film thickness, composition of the dewetting liquid, and time of annealing. Ordered dewetted structures are obtained simply by creating spatial variation of viscosity by ultraviolet exposure or by photopatterning before dewetting. Further, the structures thus fabricated are readily photopatterned again on the finer length scales after dewetting. We illustrate the approach by fabricating several three-dimensional structures of varying complexity with secondary and tertiary features.

Time-Dependent Measure of a Nano-Scale Force-Pulse Driven by the Axonemal Dynein Motors in Individual Live Sperm Cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Allen, M J; Rudd, R E; McElfresh, M W

Nano-scale mechanical forces generated by motor proteins are crucial to normal cellular and organismal functioning. The ability to measure and exploit such forces would be important to developing motile biomimetic nanodevices powered by biological motors for Nanomedicine. Axonemal dynein motors positioned inside the sperm flagellum drive microtubule sliding giving rise to rhythmic beating of the flagellum. This force-generating action makes it possible for the sperm cell to move through viscous media. Here we report new nano-scale information on how the propulsive force is generated by the sperm flagellum and how this force varies over time. Single cell recordings reveal discretemore » {approx}50 ms pulses oscillating with amplitude 9.8 {+-} 2.6 nN independent of pulse frequency (3.5-19.5 Hz). The average work carried out by each cell is 4.6 x 10{sup -16} J per pulse, equivalent to the hydrolysis of {approx}5,500 ATP molecules. The mechanochemical coupling at each active dynein head is {approx}2.2 pN/ATP, and {approx}3.9 pN per dynein arm, in agreement with previously published values obtained using different methods.« less

A Nano-indentation Identification Technique for Viscoelastic Constitutive Characteristics of Periodontal Ligaments

PubMed Central

Ashrafi, H.; Shariyat, M.

2016-01-01

Introduction Nano-indentation has recently been employed as a powerful tool for determining the mechanical properties of biological tissues on nano and micro scales. A majority of soft biological tissues such as ligaments and tendons exhibit viscoelastic or time-dependent behaviors. The constitutive characterization of soft tissues is among very important subjects in clinical medicine and especially, biomechanics fields. Periodontal ligament plays an important role in initiating tooth movement when loads are applied to teeth with orthodontic appliances. It is also the most accessible ligament in human body as it can be directly manipulated without any surgical intervention. From a mechanical point of view, this ligament can be considered as a thin interface made by a solid phase, consisting mainly of collagen fibers, which is immersed into a so-called ground substance. However, the viscoelastic constitutive effects of biological tissues are seldom considered rigorous during Nano-indentation tests. Methods In the present paper, a mathematical contact approach is developed to enable determining creep compliance and relaxation modulus of distinct periodontal ligaments, using constant–rate indentation and loading time histories, respectively. An adequate curve-fitting method is presented to determine these characteristics based on the Nano-indentation of rigid Berkovich tips. Generalized Voigt-Kelvin and Wiechert models are used to model constitutive equations of periodontal ligaments, in which the relaxation and creep functions are represented by series of decaying exponential functions of time. Results Time-dependent creep compliance and relaxation function have been obtained for tissue specimens of periodontal ligaments. Conclusion To improve accuracy, relaxation and creep moduli are measured from two tests separately. Stress relaxation effects appear more rapidly than creep in the periodontal ligaments. PMID:27672630

A Nano-indentation Identification Technique for Viscoelastic Constitutive Characteristics of Periodontal Ligaments.

PubMed

Ashrafi, H; Shariyat, M

2016-06-01

Nano-indentation has recently been employed as a powerful tool for determining the mechanical properties of biological tissues on nano and micro scales. A majority of soft biological tissues such as ligaments and tendons exhibit viscoelastic or time-dependent behaviors. The constitutive characterization of soft tissues is among very important subjects in clinical medicine and especially, biomechanics fields. Periodontal ligament plays an important role in initiating tooth movement when loads are applied to teeth with orthodontic appliances. It is also the most accessible ligament in human body as it can be directly manipulated without any surgical intervention. From a mechanical point of view, this ligament can be considered as a thin interface made by a solid phase, consisting mainly of collagen fibers, which is immersed into a so-called ground substance. However, the viscoelastic constitutive effects of biological tissues are seldom considered rigorous during Nano-indentation tests. In the present paper, a mathematical contact approach is developed to enable determining creep compliance and relaxation modulus of distinct periodontal ligaments, using constant-rate indentation and loading time histories, respectively. An adequate curve-fitting method is presented to determine these characteristics based on the Nano-indentation of rigid Berkovich tips. Generalized Voigt-Kelvin and Wiechert models are used to model constitutive equations of periodontal ligaments, in which the relaxation and creep functions are represented by series of decaying exponential functions of time. Time-dependent creep compliance and relaxation function have been obtained for tissue specimens of periodontal ligaments. To improve accuracy, relaxation and creep moduli are measured from two tests separately. Stress relaxation effects appear more rapidly than creep in the periodontal ligaments.

Performance of concrete incorporating colloidal nano-silica

NASA Astrophysics Data System (ADS)

Zeidan, Mohamed Sabry

Nanotechnology, as one of the most modern fields of science, has great market potential and economic impact. The need for research in the field of nanotechnology is continuously on the rise. During the last few decades, nanotechnology was developing rapidly into many fields of applied sciences, engineering and industrial applications, especially through studies of physics, chemistry, medicine and fundamental material science. These new developments may be attributed to the fact that material properties and performance can be significantly improved and controlled through nano-scale processes and nano-structures. This research program aims at 1) further understanding the behavior of cementitious materials when amended on the nano-scale level and 2) exploring the effect of this enhancement on the microstructure of cement matrix. This study may be considered as an important step towards better understanding the use of nano-silica in concrete. The main goal of the study is to investigate the effect of using colloidal nano-silica on properties of concrete, including mechanical properties, durability, transport properties, and microstructure. The experimental program that was conducted included a laboratory investigation of concrete mixtures in which nano-silica was added to cement or to a combination of cement and Class F fly ash. Various ratios of nano-silica were used in concrete mixtures to examine the extent and types of improvements that could be imparted to concrete. The conducted experimental program assessed these improvements in terms of reactivity, mechanical properties, and durability of the mixtures under investigation. Advanced testing techniques---including mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM)---were used to investigate the effect of nano-silica on the microstructure of the tested mixtures. In addition, the effect of nano-silica on the alkali-silica reaction (ASR) was examined using various techniques, including testing

Nano Enabled Thermo-Mechanical Materials in Adhesive Joints: A New Paradigm to Materials Functionality (Preprint)

DTIC Science & Technology

2006-12-01

interface as well as to minimize the interface contact resistance. There is an on- going effort by numerous researchers of dispersing conductive nano...constituents (single wall carbon nanotube (SWCNT), multi wall carbon nano tube ( MWCNT )) in polymers (adhesive) to enhance its thermal conductivity [1...propose to use vertically aligned MWCNT in joints to enhance through-thickness conductivity [10] because of its known high thermal conductivity

Nano-imaging enabled via self-assembly

PubMed Central

McLeod, Euan; Ozcan, Aydogan

2014-01-01

SUMMARY Imaging object details with length scales below approximately 200 nm has been historically difficult for conventional microscope objective lenses because of their inability to resolve features smaller than one-half the optical wavelength. Here we review some of the recent approaches to surpass this limit by harnessing self-assembly as a fabrication mechanism. Self-assembly can be used to form individual nano- and micro-lenses, as well as to form extended arrays of such lenses. These lenses have been shown to enable imaging with resolutions as small as 50 nm half-pitch using visible light, which is well below the Abbe diffraction limit. Furthermore, self-assembled nano-lenses can be used to boost contrast and signal levels from small nano-particles, enabling them to be detected relative to background noise. Finally, alternative nano-imaging applications of self-assembly are discussed, including three-dimensional imaging, enhanced coupling from light-emitting diodes, and the fabrication of contrast agents such as quantum dots and nanoparticles. PMID:25506387

Temperature variations at nano-scale level in phase transformed nanocrystalline NiTi shape memory alloys adjacent to graphene layers.

PubMed

Amini, Abbas; Cheng, Chun; Naebe, Minoo; Church, Jeffrey S; Hameed, Nishar; Asgari, Alireza; Will, Frank

2013-07-21

The detection and control of the temperature variation at the nano-scale level of thermo-mechanical materials during a compression process have been challenging issues. In this paper, an empirical method is proposed to predict the temperature at the nano-scale level during the solid-state phase transition phenomenon in NiTi shape memory alloys. Isothermal data was used as a reference to determine the temperature change at different loading rates. The temperature of the phase transformed zone underneath the tip increased by ∼3 to 40 °C as the loading rate increased. The temperature approached a constant with further increase in indentation depth. A few layers of graphene were used to enhance the cooling process at different loading rates. Due to the presence of graphene layers the temperature beneath the tip decreased by a further ∼3 to 10 °C depending on the loading rate. Compared with highly polished NiTi, deeper indentation depths were also observed during the solid-state phase transition, especially at the rate dependent zones. Larger superelastic deformations confirmed that the latent heat transfer through the deposited graphene layers allowed a larger phase transition volume and, therefore, more stress relaxation and penetration depth.

Comparison Between Bandage Contact Lenses and Pressure Patching on the Erosion Area and Pain Scale in Patients With Corneal Erosion.

PubMed

Triharpini, Ni Nyoman; Gede Jayanegara, I Wayan; Handayani, Ariesanti Tri; Widiana, I Gde Raka

2015-01-01

Corneal erosion is common in eye emergency cases. Extensive corneal erosions result in severe pain and prolonged healing time. This study aimed to compare bandage contact lenses with pressure patching in terms of reducing the size of the erosion area, pain scale in patients with corneal erosion and its complications. A randomized open-label clinical trial was conducted. Subjects with mechanical corneal erosion were selected to use either bandage contact lenses or pressure patching. All subjects received antibiotic eye drops and 0.5% tropicamide eye drops. Evaluations were done 24 and 72 hours after treatment. The size of the corneal erosion area, pain scale, and complications were assessed. A total of 32 eyes (16 eyes in each group) were studied. The change in the size of the corneal erosion area was greater in the bandage contact lens group than in the pressure patching group, although there was no significant difference. In the bandage contact lens group, 56.25% of the eyes were healed at 24 hours and 43.75% were healed at 72 hours. In the pressure patching group, 62.50% were healed at 24 hours and 12.50% were healed at 72 hours. The change in pain scale was significantly greater in the bandage contact lens group than in the pressure patching group. No complications were found in both groups. Bandage contact lenses are an effective alternative to treating mechanical corneal erosion because of their effect in reducing pain without causing any complications.

Nano-scale synthesis of the complex silicate minerals forsterite and enstatite

DOE PAGES

Anovitz, Lawrence M.; Rondinone, Adam Justin; Sochalski-Kolbus, Lindsay; ...

2017-01-18

Olivine is a relatively common family of silicate minerals in many terrestrial and extraterrestrial environments, and is also useful as a refractory ceramic. A capability to synthesize fine particles of olivine will enable additional studies on surface reactivity under geologically relevant conditions. This paper presents a method for the synthesis of nanocrystalline samples of the magnesium end-member, forsterite (Mg 2SiO 4) in relatively large batches (15–20 g) using a sol-gel/surfactant approach. Magnesium methoxide and tetraethylorthosilicate (TEOS) are refluxed in a toluene/methanol mixture using dodecylamine as a surfactant and tert-butyl amine and water as hydrolysis agents. This material is then cleanedmore » and dried, and fired at 800 °C. Post-firing reaction in hydrogen peroxide was used to remove residual organic surfactant. X-ray diffraction showed that a pure material resulted, with a BET surface area of up to 76.6 m 2/g. Finally, the results of a preliminary attempt to use this approach to synthesize nano-scale orthopyroxene (MgSiO 3) are also reported.« less

Nanotechnologies for Composite Structures- From Nanocomposites to Multifunctional Nano-Enabled Fibre Reinforced Composites for Spacecrafts

NASA Astrophysics Data System (ADS)

Kostopoulos, Vassilis; Vavouliotis, Antonios; Baltopoulos, Athanasios; Sotiririadis, George; Masouras, Athanasios; Pambaguian, Laurent

2014-06-01

The past decade, extensive efforts have been invested in understanding the nano-scale and revealing the capabilities offered by nanotechnology products to structural materials. Nevertheless, a major issue faced lately more seriously due to the interest of industry is on how to incorporate these nano-species into the final composite structure through existing manufacturing processes and infrastructure. In this work, we present the experience obtained from the latest nanotechnology research activities supported by ESA. The paper focuses on prepreg composite manufacturing technology and addresses:- Approaches for nano-enabling of composites- Up-scaling strategies towards final structures- Latest results on performance of nano-enabledfiber reinforced compositesSeveral approaches for the utilization of nanotechnology products in structural composite structures have been proposed and are reviewed, in short along with respective achieved results. A variety of nano-fillers has been proposed and employed, individually or in combination in hybrid forms, to approach the desired performance. A major part of the work deals with the up-scaling routes of these technologies to reach final products and industrial scales and processes while meeting end-user performance.

High frequency measurements of shot noise suppression in atomic-scale metal contacts

NASA Astrophysics Data System (ADS)

Wheeler, Patrick J.; Evans, Kenneth; Russom, Jeffrey; King, Nicholas; Natelson, Douglas

2009-03-01

Shot noise provides a means of assessing the number and transmission coefficients of transmitting channels in atomic- and molecular-scale junctions. Previous experiments at low temperatures in metal and semiconductor point contacts have demonstrated the expected suppression of shot noise when junction conductance is near an integer multiple of the conductance quantum, G0≡2e^2/h. Using high frequency techniques, we demonstrate the high speed acquisition of such data at room temperature in mechanical break junctions. In clean Au contacts conductance histograms with clear peaks at G0, 2G0, and 3G0 are acquired within hours, and histograms of simultaneous measurements of the shot noise show clear suppression at those conductance values. We describe the dependence of the noise on bias voltage and analyze the noise vs. conductance histograms in terms of a model that averages over transmission coefficients.

Austenite Grain Size Control in Upstream Processing of Niobium Microalloyed Steels by Nano-Scale Precipitate Engineering of TiN-NbC Composite

NASA Astrophysics Data System (ADS)

Subramanian, S. V.; Ma, Xiaoping; Rehman, Kashif

There is a growing demand for thicker gage pipes particularly for off-shore projects. Austenite grain size control in upstream processing before pancaking is essential to obtain excellent DBTT and DWTT properties in thicker gage product. This paper examines the basic science aspects of austenite grain size control by nano-scale precipitate engineering.

Fracture and Failure in Micro- and Nano-Scale

NASA Astrophysics Data System (ADS)

Charitidis, Costas A.

Indentation and scratch in micro- and nano-scale are the most commonly used techniques for quantifying thin film and systems properties. Among them are different failure modes such as deformation, friction, fracture toughness, fatigue. Failure modes can be activated either by a cycle of indentation or by scratching of the samples to provide an estimation of the fracture toughness and interfacial fracture energies. In the present study, we report on the failure and fracture modes in two cases of engineering materials; that is transparent SiOx thin films onto poly(ethylene terephthalate) (PET) membranes and glass-ceramic materials. The SiOx/PET system meets the demands regarding scratch-resistance, wettability, biocompatibility, gas transmission, or friction, while maintaining the bulk characteristics of PET (such as easy processing, good mechanical properties, reasonably low permeability to oxygen and carbon dioxide gases (barrier properties), and good chemical coupling with antibacterial coatings). Glass-ceramic materials, since their first accidental production in the mid fifties by S.D. Stookey, have been used in a vast area of applications, from household cooktops and stoves, to missile nose cones and mirror mounts of orbital telescopes and from decorative wall coverings to medical applications. The fracture modes, namely transgranular and intergranular modes in glass-ceramic materials have paid less attention in literature comparing with ceramic materials. In the former case the crack paves its way irrespectively of the direction of the grain boundaries, i.e., the interfaces between the different phases. In the latter case the crack preferentially follows them, i.e., debonds the interfaces.

Spiders spinning electrically charged nano-fibres

PubMed Central

Kronenberger, Katrin; Vollrath, Fritz

2015-01-01

Most spider threads are on the micrometre and sub-micrometre scale. Yet, there are some spiders that spin true nano-scale fibres such as the cribellate orb spider, Uloborus plumipes. Here, we analyse the highly specialized capture silk-spinning system of this spider and compare it with the silk extrusion systems of the more standard spider dragline threads. The cribellar silk extrusion system consists of tiny, morphologically basic glands each terminating through exceptionally long and narrow ducts in uniquely shaped silk outlets. Depending on spider size, hundreds to thousands of these outlet spigots cover the cribellum, a phylogenetically ancient spinning plate. We present details on the unique functional design of the cribellate gland–duct–spigot system and discuss design requirements for its specialist fibrils. The spinning of fibres on the nano-scale seems to have been facilitated by the evolution of a highly specialist way of direct spinning, which differs from the aqua-melt silk extrusion set-up more typical for other spiders. PMID:25631231

Application of nonlocal models to nano beams. Part II: Thickness length scale effect.

PubMed

Kim, Jun-Sik

2014-10-01

Applicability of nonlocal models to nano-beams is discussed in terms of the Eringen's nonlocal Euler-Bernoulli (EB) beam model. In literature, most work has taken the axial coordinate derivative in the Laplacian operator presented in nonlocal elasticity. This causes that the non-locality always makes the beam soften as compared to the local counterpart. In this paper, the thickness scale effect is solely considered to investigate if the nonlocal model can simulate stiffening effect. Taking the thickness derivative in the Laplacian operator leads to the presence of a surface stress state. The governing equation derived is compared to that of the EB model with the surface stress. The results obtained reveal that the nonlocality tends to decrease the bending moment stiffness whereas to increase the bending rigidity in the governing equation. This tendency also depends on the surface conditions.

Nano-scale Stripe Structures on FeTe Observed by Low-temperature STM/STS

NASA Astrophysics Data System (ADS)

Sugimoto, A.; Ukita, R.; Ekino, T.

We have investigated the nano-scale stripe structures on a parent compound of the iron chalcogenide superconductor Fe1+dTe (d=0.033) by using low-temperature scanning tunneling microscopy (STM). The STM topographies and the dI/dV maps show clear stripe structures with the period of twice as large as the Te-Te atomic displacement (~0.76 nm = 2a0, a0 is lattice constant), in addition to weak modulation with the same period of lattice constant (~0.38 nm). The bias-voltage dependence of both STM topographies and dI/dV maps show the several kinds of the stripe structures. The 2a0 modulations are similar to the bicollinear spin order of the parent compound FeTe, indicating the possibility of the coupling with spin density wave and electronic structures.

Enhanced fluoride adsorption by nano crystalline γ-alumina: adsorption kinetics, isotherm modeling and thermodynamic studies

NASA Astrophysics Data System (ADS)

Chinnakoti, Prathibha; Chunduri, Avinash L. A.; Vankayala, Ranganayakulu K.; Patnaik, Sandeep; Kamisetti, Venkataramaniah

2017-09-01

Nano materials in particular nano oxides with enhanced surface area and an excellent catalytic surface serve as potential adsorbents for defluoridation of water. In the present study nano γ-alumina was synthesized through a simple and low cost, surfactant assisted solution combustion method. As synthesized material was characterized by XRD and FESEM for its phase, size and morphological characteristics. Surface properties have been investigated by BET method. Nano γ-alumina was further used for a detailed adsorption study to remove fluoride from water. Batches of experiments were performed at various experimental conditions such as solution pH, adsorbent dose, initial fluoride concentration and contact time to test the defluoridation ability of γ-alumina. Fluoride Adsorption by nano sized γ-alumina was rapid and reached equilibrium within two hours. The adsorption worked well at pH 4.0, where ˜96 % of fluoride was found to be adsorbed on adsorbent. It was possible to reduce fluoride levels to as low as 0.3 mg/L (within the safe limit of WHO: ≤1.5 mg/L) from an initial fluoride levels of 10 mg/L. This could be achieved using a very small quantity, 1 g/L of γ-alumina at pH 4 within 1 h of contact time. Defluoridation capacity of nano γ-alumina was further investigated by fitting the equilibrium data to various isotherm as well as kinetic models. The present study revealed that γ-alumina could be an efficient adsorbent for treating fluoride contaminated water.

Spun-wrapped aligned nanofiber (SWAN) lithography for fabrication of micro/nano-structures on 3D objects

NASA Astrophysics Data System (ADS)

Ye, Zhou; Nain, Amrinder S.; Behkam, Bahareh

2016-06-01

Fabrication of micro/nano-structures on irregularly shaped substrates and three-dimensional (3D) objects is of significant interest in diverse technological fields. However, it remains a formidable challenge thwarted by limited adaptability of the state-of-the-art nanolithography techniques for nanofabrication on non-planar surfaces. In this work, we introduce Spun-Wrapped Aligned Nanofiber (SWAN) lithography, a versatile, scalable, and cost-effective technique for fabrication of multiscale (nano to microscale) structures on 3D objects without restriction on substrate material and geometry. SWAN lithography combines precise deposition of polymeric nanofiber masks, in aligned single or multilayer configurations, with well-controlled solvent vapor treatment and etching processes to enable high throughput (>10-7 m2 s-1) and large-area fabrication of sub-50 nm to several micron features with high pattern fidelity. Using this technique, we demonstrate whole-surface nanopatterning of bulk and thin film surfaces of cubes, cylinders, and hyperbola-shaped objects that would be difficult, if not impossible to achieve with existing methods. We demonstrate that the fabricated feature size (b) scales with the fiber mask diameter (D) as b1.5 ~ D. This scaling law is in excellent agreement with theoretical predictions using the Johnson, Kendall, and Roberts (JKR) contact theory, thus providing a rational design framework for fabrication of systems and devices that require precisely designed multiscale features.Fabrication of micro/nano-structures on irregularly shaped substrates and three-dimensional (3D) objects is of significant interest in diverse technological fields. However, it remains a formidable challenge thwarted by limited adaptability of the state-of-the-art nanolithography techniques for nanofabrication on non-planar surfaces. In this work, we introduce Spun-Wrapped Aligned Nanofiber (SWAN) lithography, a versatile, scalable, and cost-effective technique for

Multi-scale predictive modeling of nano-material and realistic electron devices

NASA Astrophysics Data System (ADS)

Palaria, Amritanshu

Among the challenges faced in further miniaturization of electronic devices, heavy influence of the detailed atomic configuration of the material(s) involved, which often differs significantly from that of the bulk material(s), is prominent. Device design has therefore become highly interrelated with material engineering at the atomic level. This thesis aims at outlining, with examples, a multi-scale simulation procedure that allows one to integrate material and device aspects of nano-electronic design to predict behavior of novel devices with novel material. This is followed in four parts: (1) An approach that combines a higher time scale reactive force field analysis with density functional theory to predict structure of new material is demonstrated for the first time for nanowires. Novel stable structures for very small diameter silicon nanowires are predicted. (2) Density functional theory is used to show that the new nanowire structures derived in 1 above have properties different from diamond core wires even though the surface bonds in some may be similar to the surface of bulk silicon. (3) Electronic structure of relatively large-scale germanium sections of realistically strained Si/strained Ge/ strained Si nanowire heterostructures is computed using empirical tight binding and it is shown that the average non-homogeneous strain in these structures drives their interesting non-conventional electronic characteristics such as hole effective masses which decrease as the wire cross-section is reduced. (4) It is shown that tight binding, though empirical in nature, is not necessarily limited to the material and atomic structure for which the parameters have been empirically derived, but that simple changes may adapt the derived parameters to new bond environments. Si (100) surface electronic structure is obtained from bulk Si parameters.

The Neurologic Assessment in Neuro-Oncology (NANO) scale: a tool to assess neurologic function for integration into the Response Assessment in Neuro-Oncology (RANO) criteria

PubMed Central

DeAngelis, Lisa M.; Brandes, Alba A.; Peereboom, David M.; Galanis, Evanthia; Lin, Nancy U.; Soffietti, Riccardo; Macdonald, David R.; Chamberlain, Marc; Perry, James; Jaeckle, Kurt; Mehta, Minesh; Stupp, Roger; Muzikansky, Alona; Pentsova, Elena; Cloughesy, Timothy; Iwamoto, Fabio M.; Tonn, Joerg-Christian; Vogelbaum, Michael A.; Wen, Patrick Y.; van den Bent, Martin J.; Reardon, David A.

2017-01-01

Abstract Background. The Macdonald criteria and the Response Assessment in Neuro-Oncology (RANO) criteria define radiologic parameters to classify therapeutic outcome among patients with malignant glioma and specify that clinical status must be incorporated and prioritized for overall assessment. But neither provides specific parameters to do so. We hypothesized that a standardized metric to measure neurologic function will permit more effective overall response assessment in neuro-oncology. Methods. An international group of physicians including neurologists, medical oncologists, radiation oncologists, and neurosurgeons with expertise in neuro-oncology drafted the Neurologic Assessment in Neuro-Oncology (NANO) scale as an objective and quantifiable metric of neurologic function evaluable during a routine office examination. The scale was subsequently tested in a multicenter study to determine its overall reliability, inter-observer variability, and feasibility. Results. The NANO scale is a quantifiable evaluation of 9 relevant neurologic domains based on direct observation and testing conducted during routine office visits. The score defines overall response criteria. A prospective, multinational study noted a >90% inter-observer agreement rate with kappa statistic ranging from 0.35 to 0.83 (fair to almost perfect agreement), and a median assessment time of 4 minutes (interquartile range, 3–5). Conclusion. The NANO scale provides an objective clinician-reported outcome of neurologic function with high inter-observer agreement. It is designed to combine with radiographic assessment to provide an overall assessment of outcome for neuro-oncology patients in clinical trials and in daily practice. Furthermore, it complements existing patient-reported outcomes and cognition testing to combine for a global clinical outcome assessment of well-being among brain tumor patients. PMID:28453751

Semi-flexible polymer engendered aggregation/dispersion of fullerene (C60) nano-particles: An atomistic investigation

NASA Astrophysics Data System (ADS)

Kumar, Sunil; Pattanayek, Sudip K.

2018-06-01

Semi flexible polymer chain has been modeled by choosing various values of persistent length (stiffness). As the polymer chain stiffness increases, the shape of polymer chain changes from globule to extended cigar to toroid like structure during cooling from a high temperature. The aggregation of fullerene nano-particles is found to depend on the morphology of polymer chain. To maximize, the number of polymer bead-nanoparticle contacts, all nano-particle have positioned inside the polymer globule. To minimize, the energy penalty, due to bending of the polymer chain, all nano-particle have positioned on the surface of the polymer's cigar and toroid morphology.

Pinning in high performance MgB2 thin films and bulks: Role of Mg-B-O nano-scale inhomogeneities

NASA Astrophysics Data System (ADS)

Prikhna, Tatiana; Shapovalov, Andrey; Eisterer, Michael; Shaternik, Vladimir; Goldacker, Wilfried; Weber, Harald W.; Moshchil, Viktor; Kozyrev, Artem; Sverdun, Vladimir; Boutko, Viktor; Grechnev, Gennadiy; Gusev, Alexandr; Kovylaev, Valeriy; Shaternik, Anton

2017-02-01

The comparison of nano-crystalline MgB2 oxygen-containing thin film (140 nm) and highly dense bulk materials showed that the critical current density, Jc, depends on the distribution of Mg-B-O nano-scale inhomogeneities. It has been shown that MgB2 bulks with high Jc in low (∼106 A/cm2 in 0-1 T at 10 K) and medium magnetic fields contain MgB0.6-0.8O0.8-0.9 nano-inclusions, where δTc or a combined δTc (dominant) / δl pinning mechanism prevails, while in bulk MgB2 with high Jc in high magnetic fields (Birr(18.5 K) = 15 T, Bc2(0 K) = 42.1 T) MgB1.2-2.7O1.8-2.5 nano-layers are present and δl pinning prevails. The structure of oxygen-containing films with high Jc in low and high magnetic fields (Jc (0 Т) = 1.8 × 107 А/сm2 and Jc (5 Т) = 2 × 106 А/сm2 at 10 К) contains very fine oxygen-enriched Mg-B-O inhomogeneities and δl pinning is realized. The results of DOS calculations in MgB2-xOx cells for x = 0, 0.125, 0.25, 0.5, 1 demonstrate that all compounds are conductors with metal-like behaviour. In the case of ordered oxygen substitution for boron the binding energy, Eb, does not increase sufficiently as compared with that for MgB2, while when oxygen atoms form zigzag chains the calculated Eb is even lower (Eb = -1.15712 Ry).

Carrier mobility enhancement of nano-crystalline semiconductor films: Incorporation of redox -relay species into the grain boundary interface

NASA Astrophysics Data System (ADS)

Desilva, L. A.; Bandara, T. M. W. J.; Hettiarachchi, B. H.; Kumara, G. R. A.; Perera, A. G. U.; Rajapaksa, R. M. G.; Tennakone, K.

Dye-sensitized and perovskite solar cells and other nanostructured heterojunction electronic devices require securing intimate electronic contact between nanostructured surfaces. Generally, the strategy is solution phase coating of a hole -collector over a nano-crystalline high-band gap n-type oxide semiconductor film painted with a thin layer of the light harvesting material. The nano-crystallites of the hole - collector fills the pores of the painted oxide surface. Most ills of these devices are associated with imperfect contact and high resistance of the hole conducting layer constituted of nano-crystallites. Denaturing of the delicate light harvesting material forbid sintering at elevated temperatures to reduce the grain boundary resistance. It is found that the interfacial and grain boundary resistance can be significantly reduced via incorporation of redox species into the interfaces to form ultra-thin layers. Suitable redox moieties, preferably bonded to the surface, act as electron transfer relays greatly reducing the film resistance offerring a promising method of enhancing the effective hole mobility of nano-crystalline hole-collectors and developing hole conductor paints for application in nanostructured devices.

Phosphatidylserine Stimulates Ceramide 1-Phosphate (C1P) Intermembrane Transfer by C1P Transfer Proteins.

PubMed

Zhai, Xiuhong; Gao, Yong-Guang; Mishra, Shrawan K; Simanshu, Dhirendra K; Boldyrev, Ivan A; Benson, Linda M; Bergen, H Robert; Malinina, Lucy; Mundy, John; Molotkovsky, Julian G; Patel, Dinshaw J; Brown, Rhoderick E

2017-02-10

Genetic models for studying localized cell suicide that halt the spread of pathogen infection and immune response activation in plants include Arabidopsis accelerated-cell-death 11 mutant ( acd11 ). In this mutant, sphingolipid homeostasis is disrupted via depletion of ACD11, a lipid transfer protein that is specific for ceramide 1-phosphate (C1P) and phyto-C1P. The C1P binding site in ACD11 and in human ceramide-1-phosphate transfer protein (CPTP) is surrounded by cationic residues. Here, we investigated the functional regulation of ACD11 and CPTP by anionic phosphoglycerides and found that 1-palmitoyl-2-oleoyl-phosphatidic acid or 1-palmitoyl-2-oleoyl-phosphatidylglycerol (≤15 mol %) in C1P source vesicles depressed C1P intermembrane transfer. By contrast, replacement with 1-palmitoyl-2-oleoyl-phosphatidylserine stimulated C1P transfer by ACD11 and CPTP. Notably, "soluble" phosphatidylserine (dihexanoyl-phosphatidylserine) failed to stimulate C1P transfer. Also, none of the anionic phosphoglycerides affected transfer action by human glycolipid lipid transfer protein (GLTP), which is glycolipid-specific and has few cationic residues near its glycolipid binding site. These findings provide the first evidence for a potential phosphoglyceride headgroup-specific regulatory interaction site(s) existing on the surface of any GLTP-fold and delineate new differences between GLTP superfamily members that are specific for C1P versus glycolipid. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Behavior of a nano-particle and a polymer molecule in a nano-scale four-roll mill

NASA Astrophysics Data System (ADS)

Vo, Minh; Papavassiliou, Dimitrios

2016-11-01

The four-roll mill device could be used to create a mixed flow from purely extensional stresses to completely rotational through the proper selection of speed and direction of each of the four cylindrical rollers. Considerable research has been done with this device for macroscale rheological studies.. In our study, the dissipative particle dynamics (DPD) method was employed to investigate the behavior of a nano-sphere and a polymer molecule in different conditions within a four-roll mill device. Hydrophilic properties of each roll were generated by adjusting interaction parameters and using bounce back boundary condition at the solid surface. All simulations were run up to 4x106 time steps at room temperature using the open source LAMMPS package. After the flow in the system reached equilibrium, a nano-sphere and then a polymer chain were released at the center of the simulation box. Their trajectories were recorded at different shear rate conditions. The propagation of nanosphere in different rotational flow will be discussed. Additionally, the deformation of polymer chains will be compared to that in a simple shear flow.

Uniting Superhydrophobic, Superoleophobic and Lubricant Infused Slippery Behavior on Copper Oxide Nano-structured Substrates

PubMed Central

Ujjain, Sanjeev Kumar; Roy, Pritam Kumar; Kumar, Sumana; Singha, Subhash; Khare, Krishnacharya

2016-01-01

Alloys, specifically steel, are considered as the workhorse of our society and are inimitable engineering materials in the field of infrastructure, industry and possesses significant applications in our daily life. However, creating a robust synthetic metallic surface that repels various liquids has remained extremely challenging. The wettability of a solid surface is known to be governed by its geometric nano-/micro structure and the chemical composition. Here, we are demonstrating a facile and economical way to generate copper oxide micro-nano structures with spherical (0D), needle (1D) and hierarchical cauliflower (3D) morphologies on galvanized steel substrates using a simple chemical bath deposition method. These nano/micro textured steel surfaces, on subsequent coating of a low surface energy material display excellent superhydrophobic, superoleophobic and slippery behavior. Polydimethylsiloxane coated textured surfaces illustrate superhydrophobicity with water contact angle about 160°(2) and critical sliding angle ~2°. When functionalized with low-surface energy perfluoroalkylsilane, these surfaces display high repellency for low surface tension oils as well as hydrocarbons. Among them, the hierarchical cauliflower morphology exhibits re-entrant structure thereby showing the best superoleophobicity with contact angle 149° for dodecane. Once infused with a lubricant like silicone oil, they show excellent slippery behavior with low contact angle hysteresis (~ 2°) for water drops. PMID:27752098

Large-scale and highly efficient synthesis of micro- and nano-fibers with controlled fiber morphology by centrifugal jet spinning for tissue regeneration

NASA Astrophysics Data System (ADS)

Ren, Liyun; Pandit, Vaibhav; Elkin, Joshua; Denman, Tyler; Cooper, James A.; Kotha, Shiva P.

2013-02-01

PLLA fibrous tissue scaffolds with controlled fiber nanoscale surface roughness are fabricated with a novel centrifugal jet spinning process. The centrifugal jet spinning technique is a highly efficient synthesis method for micron- to nano-sized fibers with a production rate up to 0.5 g min-1. During the centrifugal jet spinning process, a polymer solution jet is stretched by the centrifugal force of a rotating chamber. By engineering the rheological properties of the polymer solution, solvent evaporation rate and centrifugal force that are applied on the solution jet, polyvinylpyrrolidone (PVP) and poly(l-lactic acid) (PLLA) composite fibers with various diameters are fabricated. Viscosity measurements of polymer solutions allowed us to determine critical polymer chain entanglement limits that allow the generation of continuous fiber as opposed to beads or beaded fibers. Above a critical concentration at which polymer chains are partially or fully entangled, lower polymer concentrations and higher centrifugal forces resulted in thinner fibers. Etching of PVP from the PLLA-PVP composite fibers doped with increasing PVP concentrations yielded PLLA fibers with increasing nano-scale surface roughness and porosity, which increased the fiber hydrophilicity dramatically. Scanning electron micrographs of the etched composite fibers suggest that PVP and PLLA were co-contiguously phase separated within the composite fibers during spinning and nano-scale roughness features were created after the partial etching of PVP. To study the tissue regeneration efficacy of the engineered PLLA fiber matrix, human dermal fibroblasts are used to simulate partial skin graft. Fibers with increased PLLA surface roughness and porosity demonstrated a trend towards higher cell attachment and proliferation.PLLA fibrous tissue scaffolds with controlled fiber nanoscale surface roughness are fabricated with a novel centrifugal jet spinning process. The centrifugal jet spinning technique is a

A review on the application of inorganic nano-structured materials in the modification of textiles: focus on anti-microbial properties.

PubMed

Dastjerdi, Roya; Montazer, Majid

2010-08-01

Textiles can provide a suitable substrate to grow micro-organisms especially at appropriate humidity and temperature in contact to human body. Recently, increasing public concern about hygiene has been driving many investigations for anti-microbial modification of textiles. However, using many anti-microbial agents has been avoided because of their possible harmful or toxic effects. Application of inorganic nano-particles and their nano-composites would be a good alternative. This review paper has focused on the properties and applications of inorganic nano-structured materials with good anti-microbial activity potential for textile modification. The discussed nano-structured anti-microbial agents include TiO(2) nano-particles, metallic and non-metallic TiO(2) nano-composites, titania nanotubes (TNTs), silver nano-particles, silver-based nano-structured materials, gold nano-particles, zinc oxide nano-particles and nano-rods, copper nano-particles, carbon nanotubes (CNTs), nano-clay and its modified forms, gallium, liposomes loaded nano-particles, metallic and inorganic dendrimers nano-composite, nano-capsules and cyclodextrins containing nano-particles. This review is also concerned with the application methods for the modification of textiles using nano-structured materials. Copyright 2010 Elsevier B.V. All rights reserved.

[Construction of a multiple-scale implant surface with super-hydrophilicity].

PubMed

Luo, Qiao-jie; Li, Xiao-dong; Huang, Ying; Zhao, Shi-fang

2012-05-01

To construct a multiple-scale organized implant surface with super-hydrophilicity. The SiC paper polished titanium disc was sandblasted and treated with HF/HNO₃ and HCl/H₂SO₄, then acid-etched with H₂SO₄/H₂O₂. The physicochemical properties of the surfaces were characterized by scanning electron microscope, static state contact angle and X-ray diffraction. MC3T3-E1 cells were used to evaluate the effects of the surface on the cell adhesion, proliferation and differentiation. The acid-etching process with a mixture of H₂SO₄/H₂O₂ superimposed the nano-scale structure on the micro-scale texture. The multiple-scale implant surface promoted its hydrophilicity and was more favorable to the responses of osteoprogenitor cells, characterized by increased DNA content, enhanced ALP activity and promoted OC production. A multiple-scale implant surface with super-hydrophilicity has been constructed in this study, which facilitates cell proliferation and adhesion.

Nano- and Macro-wear of Bio-carbo-nitrided AISI 8620 Steel Surfaces

NASA Astrophysics Data System (ADS)

Arthur, Emmanuel Kwesi; Ampaw, Edward; Zebaze Kana, M. G.; Adetunji, A. R.; Olusunle, S. O. O.; Adewoye, O. O.; Soboyejo, W. O.

2015-12-01

This paper presents the results of an experimental study of nano- and macro-scale wear in a carbo-nitrided AISI 8620 steel. Carbo-nitriding is carried out using a novel method that involves the use of dried, cyanide-containing cassava leaves, as sources of carbon and nitrogen. These are used in a pack cementation that is used to diffuse carbon and nitrogen into case layers at intermediate temperatures [673.15 K, 723.15 K, 773.15 K, and 823.15 K (400 °C, 450 °C, 500 °C, and 550 °C)]. Nano- and macro-scale wear properties are studied in the case-hardened surfaces, using a combination of nano-scratch and pin-on-disk experiments. The measured wear volumes (at both nano- and macro-length scales) are shown to increase with decreasing pack cyaniding temperature. The nano- and macro-wear resistances are also shown to be enhanced by the in situ diffusion of carbon and nitrogen from cyanide-containing bio-processed waste. The underlying wear mechanisms are also elucidated via atomic force microscopy and scanning electron microscopy observations of the wear tracks. The implications of the results are discussed for the design of hardened carbo-nitrided steel surfaces with improved wear resistance.

Environmentally benign graphite intercalation compound composition for exfoliated graphite, flexible graphite, and nano-scaled graphene platelets

DOEpatents

Zhamu, Aruna; Jang, Bor Z.

2014-06-17

A carboxylic-intercalated graphite compound composition for the production of exfoliated graphite, flexible graphite, or nano-scaled graphene platelets. The composition comprises a layered graphite with interlayer spaces or interstices and a carboxylic acid residing in at least one of the interstices, wherein the composition is prepared by a chemical oxidation reaction which uses a combination of a carboxylic acid and hydrogen peroxide as an intercalate source. Alternatively, the composition may be prepared by an electrochemical reaction, which uses a carboxylic acid as both an electrolyte and an intercalate source. Exfoliation of the invented composition does not release undesirable chemical contaminants into air or drainage.

Tunable nano-scale graphene-based devices in mid-infrared wavelengths composed of cylindrical resonators

NASA Astrophysics Data System (ADS)

Asgari, Somayyeh; Ghattan Kashani, Zahra; Granpayeh, Nosrat

2018-04-01

The performances of three optical devices including a refractive index sensor, a power splitter, and a 4-channel multi/demultiplexer based on graphene cylindrical resonators are proposed, analyzed, and simulated numerically by using the finite-difference time-domain method. The proposed sensor operates on the principle of the shift in resonance wavelength with a change in the refractive index of dielectric materials. The sensor sensitivity has been numerically derived. In addition, the performances of the power splitter and the multi/demultiplexer based on the variation of the resonance wavelengths of cylindrical resonator have been thoroughly investigated. The simulation results are in good agreement with the theoretical ones. Our studies demonstrate that the graphene based ultra-compact, nano-scale devices can be improved to be used as photonic integrated devices, optical switching, and logic gates.

Controlling nitrogen migration through micro-nano networks

NASA Astrophysics Data System (ADS)

Cai, Dongqing; Wu, Zhengyan; Jiang, Jiang; Wu, Yuejin; Feng, Huiyun; Brown, Ian G.; Chu, Paul K.; Yu, Zengliang

2014-01-01

Nitrogen fertilizer unabsorbed by crops eventually discharges into the environment through runoff, leaching and volatilization, resulting in three-dimensional (3D) pollution spanning from underground into space. Here we describe an approach for controlling nitrogen loss, developed using loss control fertilizer (LCF) prepared by adding modified natural nanoclay (attapulgite) to traditional fertilizer. In the aqueous phase, LCF self-assembles to form 3D micro/nano networks via hydrogen bonds and other weak interactions, obtaining a higher nitrogen spatial scale so that it is retained by a soil filtering layer. Thus nitrogen loss is reduced and sufficient nutrition for crops is supplied, while the pollution risk of the fertilizer is substantially lowered. As such, self-fabrication of nano-material was used to manipulate the nitrogen spatial scale, which provides a novel and promising approach for the research and control of the migration of other micro-scaled pollutants in environmental medium.

Controlling nitrogen migration through micro-nano networks.

PubMed

Cai, Dongqing; Wu, Zhengyan; Jiang, Jiang; Wu, Yuejin; Feng, Huiyun; Brown, Ian G; Chu, Paul K; Yu, Zengliang

2014-01-14

Nitrogen fertilizer unabsorbed by crops eventually discharges into the environment through runoff, leaching and volatilization, resulting in three-dimensional (3D) pollution spanning from underground into space. Here we describe an approach for controlling nitrogen loss, developed using loss control fertilizer (LCF) prepared by adding modified natural nanoclay (attapulgite) to traditional fertilizer. In the aqueous phase, LCF self-assembles to form 3D micro/nano networks via hydrogen bonds and other weak interactions, obtaining a higher nitrogen spatial scale so that it is retained by a soil filtering layer. Thus nitrogen loss is reduced and sufficient nutrition for crops is supplied, while the pollution risk of the fertilizer is substantially lowered. As such, self-fabrication of nano-material was used to manipulate the nitrogen spatial scale, which provides a novel and promising approach for the research and control of the migration of other micro-scaled pollutants in environmental medium.

Controlling nitrogen migration through micro-nano networks

PubMed Central

Cai, Dongqing; Wu, Zhengyan; Jiang, Jiang; Wu, Yuejin; Feng, Huiyun; Brown, Ian G.; Chu, Paul K.; Yu, Zengliang

2014-01-01

Nitrogen fertilizer unabsorbed by crops eventually discharges into the environment through runoff, leaching and volatilization, resulting in three-dimensional (3D) pollution spanning from underground into space. Here we describe an approach for controlling nitrogen loss, developed using loss control fertilizer (LCF) prepared by adding modified natural nanoclay (attapulgite) to traditional fertilizer. In the aqueous phase, LCF self-assembles to form 3D micro/nano networks via hydrogen bonds and other weak interactions, obtaining a higher nitrogen spatial scale so that it is retained by a soil filtering layer. Thus nitrogen loss is reduced and sufficient nutrition for crops is supplied, while the pollution risk of the fertilizer is substantially lowered. As such, self-fabrication of nano-material was used to manipulate the nitrogen spatial scale, which provides a novel and promising approach for the research and control of the migration of other micro-scaled pollutants in environmental medium. PMID:24419037

Tunable far-infrared plasmonically induced transparency in graphene based nano-structures

NASA Astrophysics Data System (ADS)

Dolatabady, Alireza; Granpayeh, Nosrat

2018-07-01

In this paper, a structure is proposed to show the phenomenon of tunable far-infrared plasmonically induced transparency. The structure includes a nano-ribbon waveguide side-coupled to nano-stub resonators. The realized effect is due to the coupling between the consecutive nano-stub resonators spaced in properly designed distances, providing a constructive interference in the virtually created Fabry–Perot cavity. Due to the Fabry–Perot like cavity created between two consecutive nano-stubs, periodic values of nano-stubs separation can produce transparency windows. Increasing the number of nano-stubs would increase the number of transparency windows in different frequencies. The structure is theoretically investigated and numerically simulated by using the finite difference time domain method. Owing to the chemical potential dependency of graphene conductivity, the transparency windows can be actively tuned. The proposed component can be extensively utilized in nano-scale switching and slow-light systems.

Sediment toxicity and bioaccumulation of nano and micron-sized aluminum oxide.

PubMed

Stanley, Jacob K; Coleman, Jessica G; Weiss, Charles A; Steevens, Jeffery A

2010-02-01

Nano-aluminum oxide (Al(2)O(3)) is used commercially in coatings and abrasives. Nano-Al(2)O(3) can also be generated through the oxidation of nano-aluminum in military propellants and energetics. The purpose of the present study was to assess toxicity and bioaccumulation of nano-Al(2)O(3) to a variety of sediment organisms (Tubifex tubifex, Hyalella azteca, Lumbriculus variegatus, and Corbicula fluminea). The bioaccumulation and toxicity of nano-Al(2)O(3) was compared with that of micron-sized Al(2)O(3) to investigate potential size-related effects. Results of the present study show species-specific differences in relative bioaccumulation of nano and micron-sized Al(2)O(3). Significant toxic effects (survival and growth) were observed in H. azteca testing, but only at high concentrations unlikely to be found in the environment. Nano-Al(2)O(3) was found to be more toxic than micron-sized Al(2)O(3) to H. azteca survival in a 14-d study in which organisms were in direct contact with a thin layer of 625 or 2,500 mg of Al(2)O(3) dispersed on the surface of either sediment or sand. A significant growth effect was also observed for nano but not micron-sized Al(2)O(3) at the highest treatment level tested (100 g/kg Al(2)O(3)) in a 10-d H. azteca bioassay in which Al(2)O(3) was homogenized with sediment. However, differences in measured sediment Al concentrations (micron-sized = 55.1 [+/-0.6] g/kg Al; nano-sized = 66.2 [+/-0.6] g/kg Al) in the nano and micron-sized Al(2)O(3) preclude direct comparison of the toxicity of these two treatments based on particle size. Copyright 2009 SETAC.

Nano-Ag complexes prepared by γ-radiolysis and their structures and physical properties

NASA Astrophysics Data System (ADS)

Kim, Hwa-Jung; Choi, Seong-Ho; Park, Hae-Jun

2012-10-01

In this study, nano-silver (nano-Ag) complexes showing different properties have been synthesized as follows. Polypyrrolidone (PVP)-stabilized silver colloids (NAg), nano-Ag bound to silica (SiO2) (NSS), and nano-Ag bound to a complex of SiO2 and polyaniline (PANI) (NSSPAI) were prepared via γ-irradiation at room temperature. NAg and NSS used PVP as a colloidal stabilizer, while NSSPAI did not use PVP as a colloidal stabilizer. Interesting bonding properties occurred in the nano-Ag complex and anticipated structural changes were clearly shown through a surface analysis of x-ray photoelectron spectroscopy (XPS). The morphologies by field emission-scanning electron microscopy (FE-SEM) analysis showed that nano-Ag complexes have various particle sizes ranging from 10 to 30 nm. NSS (average, 10 nm) and NSSPAI (average, 30 nm) showed a uniformly spherical shape and size, while NAg did not. From the reflection peaks in the x-ray diffraction (XRD) patterns, surface crystallinity of the nano-Ag complexes was indicated to be in the same degree as that of NSSPAI>NSS>NAg. Also, in the contact angle (CA) determination, surface hydrophobicity of NSSPAI was stronger than those of NSS and NAg, relatively. The different nano-Ag complexes prepared by γ-irradiation can be applicable in various industry fields due to the increase in specific property.

Analysis of the 22-NBD-cholesterol transfer between liposome membranes and its relation to the intermembrane exchange of 25-hydroxycholesterol.

PubMed

Ishii, Haruyuki; Shimanouchi, Toshinori; Umakoshi, Hiroshi; Walde, Peter; Kuboi, Ryoichi

2010-05-01

The transfer of 22-NBD-cholesterol (22-(N-(7-Nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-23,24-bisnor-5-cholen-3-ol) between two liposome membranes was quantitatively analyzed by using the fluorescence resonance energy transfer (FRET) method. Liposomes labeled with both 22-NBD-cholesterol and a rhodamine-labeled phosphatidylethanolamine (Rh-DHPE) were used as donor liposomes, and the 22-NBD-cholesterol transfer from these donor liposomes to acceptor liposomes prepared from same type of phosphatidylcholine was monitored. The transfer kinetics was found to be composed of a fast and a slow phase, and all kinetic measurements could be fitted with a bi-exponential model. The results obtained indicate that the 22-NBD-cholesterol transfer kinetics between liposome membranes depends on the fluidity of the liposome used and that the curvature may affect the kinetics. Furthermore, the behavior of 22-NBD-cholesterol in lipid membrane is similar to that of the oxysterol 25-hydroxycholesterol rather than cholesterol. It is proposed that 22-NBD-cholesterol can be a useful fluorescent probe to mimic the intermembrane transfer of oxidized cholesterols like 25-hydroxycholesterol, rather than that of cholesterol itself. 2010 Elsevier B.V. All rights reserved.

Well-ordered polymer nano-fibers with self-cleaning property by disturbing crystallization process

NASA Astrophysics Data System (ADS)

Yang, Qin; Luo, Zhuangzhu; Tan, Sheng; Luo, Yimin; Wang, Yunjiao; Zhang, Zhaozhu; Liu, Weimin

2014-07-01

Bionic self-cleaning surfaces with well-ordered polymer nano-fibers are firstly fabricated by disturbing crystallization during one-step coating-curing process. Orderly thin (100 nm) and long (5-10 μm) polymer nano-fibers with a certain direction are fabricated by external macroscopic force ( F blow) interference introduced by H2 gas flow, leading to superior superhydrophobicity with a water contact angle (WCA) of 170° and a water sliding angle (WSA) of 0-1°. In contrast, nano-wires and nano-bridges (1-8 μm in length/10-80 nm in width) are generated by "spinning/stretching" under internal microscopic force ( F T) interference due to significant temperature difference in the non-uniform cooling medium. The findings provide a novel theoretical basis for controllable polymer "bionic lotus" surface and will further promote practical application in many engineering fields such as drag-reduction and anti-icing.

The Neurologic Assessment in Neuro-Oncology (NANO) scale: a tool to assess neurologic function for integration into the Response Assessment in Neuro-Oncology (RANO) criteria.

PubMed

Nayak, Lakshmi; DeAngelis, Lisa M; Brandes, Alba A; Peereboom, David M; Galanis, Evanthia; Lin, Nancy U; Soffietti, Riccardo; Macdonald, David R; Chamberlain, Marc; Perry, James; Jaeckle, Kurt; Mehta, Minesh; Stupp, Roger; Muzikansky, Alona; Pentsova, Elena; Cloughesy, Timothy; Iwamoto, Fabio M; Tonn, Joerg-Christian; Vogelbaum, Michael A; Wen, Patrick Y; van den Bent, Martin J; Reardon, David A

2017-05-01

The Macdonald criteria and the Response Assessment in Neuro-Oncology (RANO) criteria define radiologic parameters to classify therapeutic outcome among patients with malignant glioma and specify that clinical status must be incorporated and prioritized for overall assessment. But neither provides specific parameters to do so. We hypothesized that a standardized metric to measure neurologic function will permit more effective overall response assessment in neuro-oncology. An international group of physicians including neurologists, medical oncologists, radiation oncologists, and neurosurgeons with expertise in neuro-oncology drafted the Neurologic Assessment in Neuro-Oncology (NANO) scale as an objective and quantifiable metric of neurologic function evaluable during a routine office examination. The scale was subsequently tested in a multicenter study to determine its overall reliability, inter-observer variability, and feasibility. The NANO scale is a quantifiable evaluation of 9 relevant neurologic domains based on direct observation and testing conducted during routine office visits. The score defines overall response criteria. A prospective, multinational study noted a >90% inter-observer agreement rate with kappa statistic ranging from 0.35 to 0.83 (fair to almost perfect agreement), and a median assessment time of 4 minutes (interquartile range, 3-5). The NANO scale provides an objective clinician-reported outcome of neurologic function with high inter-observer agreement. It is designed to combine with radiographic assessment to provide an overall assessment of outcome for neuro-oncology patients in clinical trials and in daily practice. Furthermore, it complements existing patient-reported outcomes and cognition testing to combine for a global clinical outcome assessment of well-being among brain tumor patients. © The Author(s) 2017. Published by Oxford University Press on behalf of the Society for Neuro-Oncology. All rights reserved. For permissions

New understanding of nano-scale interstitial dislocation loops in BCC iron

NASA Astrophysics Data System (ADS)

Gao, N.; Chen, J.; Kurtz, R. J.; Wang, Z. G.; Zhang, R. F.; Gao, F.

2017-11-01

Complex states of nanoscale interstitial dislocation loop can be described by its habit plane and Burgers vector. Using atomistic simulations, we provide direct evidences on the change of the habit plane of a 1/2〈1 1 1〉 loop from {1 1 1} to {1 1 0} and {2 1 1}, in agreement with TEM observations. A new {1 0 0} habit plane of this loop is also predicted by simulations. The non-conservation of the Burgers vector is approved theoretically for: (1) dislocation reactions between loops with different Burgers vectors and (2) the transition between 〈1 0 0〉 loops and 1/2〈1 1 1〉 loops. The rotation from a 1/2〈1 1 1〉 to a 〈1 0 0〉 loop has also been explored, which occurs at 570 K for time on the order of 10 s. The dislocation-precipitate phase duality and change of habit plane are then proposed as new features for nano-scale dislocation loops.

Mechanochemical mechanism for reaction of aluminium nano- and micrometre-scale particles.

PubMed

Levitas, Valery I

2013-11-28

A recently suggested melt-dispersion mechanism (MDM) for fast reaction of aluminium (Al) nano- and a few micrometre-scale particles during fast heating is reviewed. Volume expansion of 6% during Al melting produces pressure of several GPa in a core and tensile hoop stresses of 10 GPa in an oxide shell. Such stresses cause dynamic fracture and spallation of the shell. After spallation, an unloading wave propagates to the centre of the particle and creates a tensile pressure of 3-8 GPa. Such a tensile pressure exceeds the cavitation strength of liquid Al and disperses the melt into small, bare clusters (fragments) that fly at a high velocity. Reaction of the clusters is not limited by diffusion through a pre-existing oxide shell. Some theoretical and experimental results related to the MDM are presented. Various theoretical predictions based on the MDM are in good qualitative and quantitative agreement with experiments, which resolves some basic puzzles in combustion of Al particles. Methods to control and improve reactivity of Al particles are formulated, which are exactly opposite to the current trends based on diffusion mechanism. Some of these suggestions have experimental confirmation.

Aerosol synthesis of nano and micro-scale zero valent metal particles from oxide precursors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Phillips, Jonathan; Luhrs, Claudia; Lesman, Zayd

2010-01-01

In this work a novel aerosol method, derived form the batch Reduction/Expansion Synthesis (RES) method, for production of nano / micro-scale metal particles from oxides and hydroxides is presented. In the Aerosol-RES (A-RES) method, an aerosol, consisting of a physical mixture of urea and metal oxide or hydroxides, is passed through a heated oven (1000 C) with a residence time of the order of 1 second, producing pure (zero valent) metal particles. It appears that the process is flexible regarding metal or alloy identity, allows control of particle size and can be readily scaled to very large throughput. Current workmore » is focused on creating nanoparticles of metal and metal alloy using this method. Although this is primarily a report on observations, some key elements of the chemistry are clear. In particular, the reducing species produced by urea decomposition are the primary agents responsible for reduction of oxides and hydroxides to metal. It is also likely that the rapid expansion that takes place when solid/liquid urea decomposes to form gas species influences the final morphology of the particles.« less

Spiders spinning electrically charged nano-fibres.

PubMed

Kronenberger, Katrin; Vollrath, Fritz

2015-01-01

Most spider threads are on the micrometre and sub-micrometre scale. Yet, there are some spiders that spin true nano-scale fibres such as the cribellate orb spider, Uloborus plumipes. Here, we analyse the highly specialized capture silk-spinning system of this spider and compare it with the silk extrusion systems of the more standard spider dragline threads. The cribellar silk extrusion system consists of tiny, morphologically basic glands each terminating through exceptionally long and narrow ducts in uniquely shaped silk outlets. Depending on spider size, hundreds to thousands of these outlet spigots cover the cribellum, a phylogenetically ancient spinning plate. We present details on the unique functional design of the cribellate gland-duct-spigot system and discuss design requirements for its specialist fibrils. The spinning of fibres on the nano-scale seems to have been facilitated by the evolution of a highly specialist way of direct spinning, which differs from the aqua-melt silk extrusion set-up more typical for other spiders. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Contact mechanics at nanometric scale using nanoindentation technique for brittle and ductile materials.

PubMed

Roa, J J; Rayon, E; Morales, M; Segarra, M

2012-06-01

In the last years, Nanoindentation or Instrumented Indentation Technique has become a powerful tool to study the mechanical properties at micro/nanometric scale (commonly known as hardness, elastic modulus and the stress-strain curve). In this review, the different contact mechanisms (elastic and elasto-plastic) are discussed, the recent patents for each mechanism (elastic and elasto-plastic) are summarized in detail, and the basic equations employed to know the mechanical behaviour for brittle and ductile materials are described.

Magnetic bead detection using nano-transformers.

PubMed

Kim, Hyung Kwon; Hwang, Jong Seung; Hwang, Sung Woo; Ahn, Doyeol

2010-11-19

A novel scheme to detect magnetic beads using a nano-scale transformer with a femtoweber resolution is reported. We have performed a Faraday's induction experiment with the nano-transformer at room temperature. The transformer shows the linear output voltage responses to the sinusoidal input current. When magnetic beads are placed on the transformer, the output responses are increased by an amount corresponding to the added magnetic flux from the beads when compared with the case of no beads on the transformer. In this way, we could determine whether magnetic beads are on top of the transformer in a single particle level.

Investigation of relationships between parameters of solar nano-flares and solar activity

NASA Astrophysics Data System (ADS)

Safari, Hossein; Javaherian, Mohsen; Kaki, Bardia

2016-07-01

Solar flares are one of the important coronal events which are originated in solar magnetic activity. They release lots of energy during the interstellar medium, right after the trigger. Flare prediction can play main role in avoiding eventual damages on the Earth. Here, to interpret solar large-scale events (e.g., flares), we investigate relationships between small-scale events (nano-flares) and large-scale events (e.g., flares). In our method, by using simulations of nano-flares based on Monte Carlo method, the intensity time series of nano-flares are simulated. Then, the solar full disk images taken at 171 angstrom recorded by SDO/AIA are employed. Some parts of the solar disk (quiet Sun (QS), coronal holes (CHs), and active regions (ARs)) are cropped and the time series of these regions are extracted. To compare the simulated intensity time series of nano-flares with the intensity time series of real data extracted from different parts of the Sun, the artificial neural networks is employed. Therefore, we are able to extract physical parameters of nano-flares like both kick and decay rate lifetime, and the power of their power-law distributions. The procedure of variations in the power value of power-law distributions within QS, CH is similar to AR. Thus, by observing the small part of the Sun, we can follow the procedure of solar activity.

Analog and RF performance of a multigate FinFET at nano scale

NASA Astrophysics Data System (ADS)

Kumar, Abhishek

2016-12-01

In this paper, analog and RF performance of the Fin field effect transistor (FET) at Nano scale is observed through 3D simulation. FinFET devices like rectangular gate all around (RE-GAA) FinFET, cylindrical gate all around (CY-GAA) FinFET and triple gate (TG) FinFET are observed. The figure of merit (FOMs) such as input-output characteristics, trans-conductance (gm), output-conductance (gd), intrinsic gain (gm/gd), gate capacitance (gate to source and total gate capacitance), unity gain cut-off frequency (ft), trans-conductance generation factor (TGF), gain frequency product (GFP), gain bandwidth product (GBP) and gain transconductance frequency product (GTFP) are observed. The analog performance of a FinFETs are observed by realising source follower circuit with NMOS transistor as a current source. The source follower circuit gain is observed. It has been observed that maximum capacitance is observed in case gate all around condition. Rectangular gate all around has the highest transconductance. In the source follower circuit, the gain curve (Vout/Vin) is sharper for TG-FinFET.

Preprotein transport machineries of yeast mitochondrial outer membrane are not required for Bax-induced release of intermembrane space proteins.

PubMed

Sanjuán Szklarz, Luiza K; Kozjak-Pavlovic, Vera; Vögtle, F-Nora; Chacinska, Agnieszka; Milenkovic, Dusanka; Vogel, Sandra; Dürr, Mark; Westermann, Benedikt; Guiard, Bernard; Martinou, Jean-Claude; Borner, Christoph; Pfanner, Nikolaus; Meisinger, Chris

2007-04-20

The mitochondrial outer membrane contains protein import machineries, the translocase of the outer membrane (TOM) and the sorting and assembly machinery (SAM). It has been speculated that TOM or SAM are required for Bax-induced release of intermembrane space (IMS) proteins; however, experimental evidence has been scarce. We used isolated yeast mitochondria as a model system and report that Bax promoted an efficient release of soluble IMS proteins while preproteins were still imported, excluding an unspecific damage of mitochondria. Removal of import receptors by protease treatment did not inhibit the release of IMS proteins by Bax. Yeast mutants of each Tom receptor and the Tom40 channel were not impaired in Bax-induced protein release. We analyzed a large collection of mutants of mitochondrial outer membrane proteins, including SAM, fusion and fission components, but none of these components was required for Bax-induced protein release. The released proteins included complexes up to a size of 230 kDa. We conclude that Bax promotes efficient release of IMS proteins through the outer membrane of yeast mitochondria while the inner membrane remains intact. Inactivation of the known protein import and sorting machineries of the outer membrane does not impair the function of Bax at the mitochondria.

The Charging Events in Contact-Separation Electrification.

PubMed

Musa, Umar G; Cezan, S Doruk; Baytekin, Bilge; Baytekin, H Tarik

2018-02-06

Contact electrification (CE)-charging of surfaces that are contacted and separated, is a common phenomenon, however it is not completely understood yet. Recent studies using surface imaging techniques and chemical analysis revealed a 'spatial' bipolar distribution of charges at the nano dimension, which made a paradigm shift in the field. However, such analyses can only provide information about the charges that remained on the surface after the separation, providing limited information about the actual course of the CE event. Tapping common polymers and metal surfaces to each other and detecting the electrical potential produced on these surfaces 'in-situ' in individual events of contact and separation, we show that, charges are generated and transferred between the surfaces in both events; the measured potential is bipolar in contact and unipolar in separation. We show, the 'contact-charges' on the surfaces are indeed the net charges that results after the separation process, and a large contribution to tribocharge harvesting comes, in fact, from the electrostatic induction resulting from the generated CE charges. Our results refine the mechanism of CE providing information for rethinking the conventional ranking of materials' charging abilities, charge harvesting, and charge prevention.

Long-Duration Carbon Dioxide Anesthesia of Fish Using Ultra Fine (Nano-Scale) Bubbles.

PubMed

Kugino, Kenji; Tamaru, Shizuka; Hisatomi, Yuko; Sakaguchi, Tadashi

2016-01-01

We investigated whether adding ultrafine (nano-scale) oxygen-carrying bubbles to water concurrently with dissolved carbon-dioxide (CO2) could result in safe, long-duration anesthesia for fish. To confirm the lethal effects of CO2 alone, fishes were anesthetized with dissolved CO2 in 20°C seawater. Within 30 minutes, all fishes, regardless of species, died suddenly due to CO2-induced narcosis, even when the water was saturated with oxygen. Death was attributed to respiration failure caused by hypoxemia. When ultrafine oxygen-carrying bubbles were supplied along with dissolved CO2, five chicken grunts were able to remain anesthetized for 22 hours and awoke normally within 2-3 hours after cessation of anesthesia. The high internal pressures and oxygen levels of the ultrafine bubbles enabled efficient oxygen diffusion across the branchia and permitted the organismal oxygen demands of individual anesthetized fish to be met. Thus, we demonstrated a method for safe, long-duration carbon dioxide anesthesia in living fish under normal water temperatures.

In yeast redistribution of Sod1 to the mitochondrial intermembrane space provides protection against respiration derived oxidative stress.

PubMed

Klöppel, Christine; Michels, Christine; Zimmer, Julia; Herrmann, Johannes M; Riemer, Jan

2010-12-03

The antioxidative enzyme copper-zinc superoxide dismutase (Sod1) is an important cellular defence system against reactive oxygen species (ROS). While the majority of this enzyme is localized to the cytosol, about 1% of the cellular Sod1 is present in the intermembrane space (IMS) of mitochondria. These amounts of mitochondrial Sod1 are increased for certain Sod1 mutants that are linked to the neurodegenerative disease amyotrophic lateral sclerosis (ALS). To date, only little is known about the physiological function of mitochondrial Sod1. Here, we use the model system Saccharomyces cerevisiae to generate cells in which Sod1 is exclusively localized to the IMS. We find that IMS-localized Sod1 can functionally substitute wild type Sod1 and that it even exceeds the protective capacity of wild type Sod1 under conditions of mitochondrial ROS stress. Moreover, we demonstrate that upon expression in yeast cells the common ALS-linked mutant Sod1(G93A) becomes enriched in the mitochondrial fraction and provides an increased protection of cells from mitochondrial oxidative stress. Such an effect cannot be observed for the catalytically inactive mutant Sod1(G85R). Our observations suggest that the targeting of Sod1 to the mitochondrial IMS provides an increased protection against respiration-derived ROS. Copyright © 2010 Elsevier Inc. All rights reserved.

Well-ordered polymer nano-fibers with self-cleaning property by disturbing crystallization process.

PubMed

Yang, Qin; Luo, Zhuangzhu; Tan, Sheng; Luo, Yimin; Wang, Yunjiao; Zhang, Zhaozhu; Liu, Weimin

2014-01-01

Bionic self-cleaning surfaces with well-ordered polymer nano-fibers are firstly fabricated by disturbing crystallization during one-step coating-curing process. Orderly thin (100 nm) and long (5-10 μm) polymer nano-fibers with a certain direction are fabricated by external macroscopic force (F blow) interference introduced by H2 gas flow, leading to superior superhydrophobicity with a water contact angle (WCA) of 170° and a water sliding angle (WSA) of 0-1°. In contrast, nano-wires and nano-bridges (1-8 μm in length/10-80 nm in width) are generated by "spinning/stretching" under internal microscopic force (F T) interference due to significant temperature difference in the non-uniform cooling medium. The findings provide a novel theoretical basis for controllable polymer "bionic lotus" surface and will further promote practical application in many engineering fields such as drag-reduction and anti-icing.

Structure of welded joints obtained by contact weld in nanostructured titanium

NASA Astrophysics Data System (ADS)

Klimenov, V. A.; Klopotov, A. A.; Gnysov, S. F.; Vlasov, V. A.; Lychagin, D. V.; Chumaevskii, A. V.

2015-10-01

The paper presents the research of the weld structure of two Ti specimens of the type VT6 that have nano- and submicrocrystalline structures. Electrical contact welding is used to obtain welds. The acicular structure is formed in the weld area. Two types of defects are detected, namely micropores and microcracks.

Structure-mechanical function relations at nano-scale in heat-affected human dental tissue.

PubMed

Sui, Tan; Sandholzer, Michael A; Le Bourhis, Eric; Baimpas, Nikolaos; Landini, Gabriel; Korsunsky, Alexander M

2014-04-01

The knowledge of the mechanical properties of dental materials related to their hierarchical structure is essential for understanding and predicting the effect of microstructural alterations on the performance of dental tissues in the context of forensic and archaeological investigation as well as laser irradiation treatment of caries. So far, few studies have focused on the nano-scale structure-mechanical function relations of human teeth altered by chemical or thermal treatment. The response of dental tissues to thermal treatment is thought to be strongly affected by the mineral crystallite size, their spatial arrangement and preferred orientation. In this study, synchrotron-based small and wide angle X-ray scattering (SAXS/WAXS) techniques were used to investigate the micro-structural alterations (mean crystalline thickness, crystal perfection and degree of alignment) of heat-affected dentine and enamel in human dental teeth. Additionally, nanoindentation mapping was applied to detect the spatial and temperature-dependent nano-mechanical properties variation. The SAXS/WAXS results revealed that the mean crystalline thickness distribution in dentine was more uniform compared with that in enamel. Although in general the mean crystalline thickness increased both in dentine and enamel as the temperature increased, the local structural variations gradually reduced. Meanwhile, the hardness and reduced modulus in enamel decreased as the temperature increased, while for dentine, the tendency reversed at high temperature. The analysis of the correlation between the ultrastructure and mechanical properties coupled with the effect of temperature demonstrates the effect of mean thickness and orientation on the local variation of mechanical property. This structural-mechanical property alteration is likely to be due to changes of HAp crystallites, thus dentine and enamel exhibit different responses at different temperatures. Our results enable an improved understanding of

On Ni/Au Alloyed Contacts to Mg-Doped GaN

NASA Astrophysics Data System (ADS)

Sarkar, Biplab; Reddy, Pramod; Klump, Andrew; Kaess, Felix; Rounds, Robert; Kirste, Ronny; Mita, Seiji; Kohn, Erhard; Collazo, Ramon; Sitar, Zlatko

2018-01-01

Ni/Au contacts to p-GaN were studied as a function of free hole concentration in GaN using planar transmission line measurement structures. All contacts showed a nonlinear behavior, which became stronger for lower doping concentrations. Electrical and structural analysis indicated that the current conduction between the contact and the p-GaN was through localized nano-sized clusters. Thus, the non-linear contact behavior can be well explained using the alloyed contact model. Two contributions to the contact resistance were identified: the spreading resistance in the semiconductor developed by the current crowding around the electrically active clusters, and diode-type behavior at the interface of the electrically active clusters with the semiconductor. Hence, the equivalent Ni/Au contact model consists of a diode and a resistor in series for each active cluster. The reduced barrier height observed in the measurements is thought to be generated by the extraction of Ga from the crystalline surface and localized formation of the Au:Ga phase. The alloyed contact analyses presented in this work are in good agreement with some of the commonly observed behavior of similar contacts described in the literature.

Moving contact lines on vibrating surfaces

NASA Astrophysics Data System (ADS)

Solomenko, Zlatko; Spelt, Peter; Scott, Julian

2017-11-01

Large-scale simulations of flows with moving contact lines for realistic conditions generally requires a subgrid scale model (analyses based on matched asymptotics) to account for the unresolved part of the flow, given the large range of length scales involved near contact lines. Existing models for the interface shape in the contact-line region are primarily for steady flows on homogeneous substrates, with encouraging results in 3D simulations. Introduction of complexities would require further investigation of the contact-line region, however. Here we study flows with moving contact lines on planar substrates subject to vibrations, with applications in controlling wetting/dewetting. The challenge here is to determine the change in interface shape near contact lines due to vibrations. To develop further insight, 2D direct numerical simulations (wherein the flow is resolved down to an imposed slip length) have been performed to enable comparison with asymptotic theory, which is also developed further. Perspectives will also be presented on the final objective of the work, which is to develop a subgrid scale model that can be utilized in large-scale simulations. The authors gratefully acknowledge the ANR for financial support (ANR-15-CE08-0031) and the meso-centre FLMSN for use of computational resources. This work was Granted access to the HPC resources of CINES under the allocation A0012B06893 made by GENCI.

Nano iron particles transport in fractured rocks: laboratory and field scale

NASA Astrophysics Data System (ADS)

Cohen, Meirav; Weisbrod, Noam

2017-04-01

Our study deals with the transport potential of nano iron particles (NIPs) in fractured media. Two different systemswere used to investigate transport on two scales: (1 )a laboratory flow system of a naturally discrete fractured chalk core, 0.43 and 0.18 m in length and diamater, respectively; and (2) a field system of hydraulically connected boreholes located 47 m apart which penetrate a fractured chalk aquifer. We started by testing the transport potential of various NIPs under different conditions. Particle stability experiments were conducted using various NIPs and different stabilizersat two ionic strengths. Overall, four different NIPs and three stabilizers were tested. Particles and solution properties (stability, aggregate/particle size, viscosity and density) were tested in batch experiments, and transport experiments (breakthrough curves (BTCs) and recovery) were conduted in the fractured chalk core. We have learned that the key parameters controlling particle transport are the particle/aggregate size and stability, which govern NIP settling rates and ultimately their migration distance. The governing mechanism controlling NIP transport was found to be sedimentation, and to a much lesser extent, processes such as diffusion, straining or interception. On the basis of these experiments, Carbo-Iron® particles ( 800 nm activated carbon particles doped with nano zero valent iron particles) and Carboxymethyl cellulose (CMC) stabilizer were selected for the field test injection. In the field, Carbo-Iron particles were initially injected into the fractured aquifer using an excess of stabilizer in order to ensure maximum recovery. This resulted in high particle recovery and fast arrival time, similar to the ideal tracer (iodide). The high recovery of the stable particle solution emphasized the importance of particle stability for transport in fractures. To test mobility manipulation potential of the particles and simulate more realistic scenarios, a second field

Rapid nano impact printing of silk biopolymer thin films

NASA Astrophysics Data System (ADS)

White, Robert D.; Gray, Caprice; Mandelup, Ethan; Amsden, Jason J.; Kaplan, David L.; Omenetto, Fiorenzo G.

2011-11-01

In this paper, nano impact printing of silk biopolymer films is described. An indenter is rapidly accelerated and transfers the nanopattern from a silicon master into the silk film during an impact event that occurs in less than 1 ms. Contact stresses of greater than 100 MPa can be achieved during the short impact period with low power and inexpensive hardware. Ring shaped features with a diameter of 2 µm and a ring width of 100-200 nm were successfully transferred into untreated silk films using this method at room temperature. Mechanical modeling was carried out to determine the contact stress distribution, and demonstrates that imprinting can occur for contact stresses of less than 2 MPa. Thermal characterization at the impact location shows that raising the temperature to 70 °C has only a limited effect on pattern transfer. Contact stresses of greater than approximately 100 MPa result in excessive deformation of the film and poor pattern transfer.

Evaluation of polyacrylonitrile electrospun nano-fibrous mats as leukocyte removal filter media.

PubMed

Pourbaghi, Raha; Zarrebini, Mohammad; Semnani, Dariush; Pourazar, Abbasali; Akbari, Nahid; Shamsfar, Reihaneh

2018-07-01

Removal of leukocytes from blood products is the most effective means for elimination of undesirable side effects and prevention of possible reactions in recipients. Micro-fibrous mats are currently used for removal of leukocytes from blood. In this study, samples of electrospun nano-fibrous mats were produced. The performance of the produced electrospun nano-fibrous mats as means of leukocytes removal from fresh whole blood was both evaluated and compared with that of commercially available micro-fibrous mats. In order to produce the samples, polyacrylonitrile (PAN) nano-fibrous mats were made under different electrospinning conditions. Mean fiber diameter, pore characterization and surface roughness of the PAN nano-fibrous mats were determined using image processing technique. In order to evaluate the surface tension of the fabricated mats, water contact angle was measured. The leukocyte removal performance, erythrocytes recovery percent and hemolysis rate of the nano-fibrous mats were compared. The effectiveness of nano-fibrous mats in removing leukocyte was established using both scanning electron microscope and optical microscope. Results showed that for given weight, the fabricated nano-fibrous mats were not only more efficient but also more cost-effective than their commercial counterparts. Results confirmed that changes in mean fiber diameter, the number of layer and weight of each layer in the absence of any chemical reaction or physical surface modification, the fabricated nano-fibrous mats were able to remove 5-log of leukocytes. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1759-1769, 2018. © 2017 Wiley Periodicals, Inc.

Impact of Subsurface Heterogeneities on nano-Scale Zero Valent Iron Transport

NASA Astrophysics Data System (ADS)

Krol, M. M.; Sleep, B. E.; O'Carroll, D. M.

2011-12-01

Nano-scale zero valent iron (nZVI) has been applied as a remediation technology at sites contaminated with chlorinated compounds and heavy metals. Although laboratory studies have demonstrated high reactivity for the degradation of target contaminants, the success of nZVI in the field has been limited due to poor subsurface mobility. When injected into the subsurface, nZVI tends to aggregate and be retained by subsurface soils. As such nZVI suspensions need to be stabilized for increased mobility. However, even with stabilization, soil heterogeneities can still lead to non-uniform nZVI transport, resulting in poor distribution and consequently decreased degradation of target compounds. Understanding how nZVI transport can be affected by subsurface heterogeneities can aid in improving the technology. This can be done with the use of a numerical model which can simulate nZVI transport. In this study CompSim, a finite difference groundwater model, is used to simulate the movement of nZVI in a two-dimensional domain. CompSim has been shown in previous studies to accurately predict nZVI movement in the subsurface, and is used in this study to examine the impact of soil heterogeneity on nZVI transport. This work also explores the impact of different viscosities of the injected nZVI suspensions (corresponding to different stabilizing polymers) and injection rates on nZVI mobility. Analysis metrics include travel time, travel distance, and average nZVI concentrations. Improving our understanding of the influence of soil heterogeneity on nZVI transport will lead to improved field scale implementation and, potentially, to more effective remediation of contaminated sites.

Simulation Studies of Mechanical Properties of Novel Silica Nano-structures

NASA Astrophysics Data System (ADS)

Muralidharan, Krishna; Torras Costa, Joan; Trickey, Samuel B.

2006-03-01

Advances in nanotechnology and the importance of silica as a technological material continue to stimulate computational study of the properties of possible novel silica nanostructures. Thus we have done classical molecular dynamics (MD) and multi-scale quantum mechanical (QM/MD) simulation studies of the mechanical properties of single-wall and multi-wall silica nano-rods of varying dimensions. Such nano-rods have been predicted by Mallik et al. to be unusually strong in tensile failure. Here we compare failure mechanisms of such nano-rods under tension, compression, and bending. The concurrent multi-scale QM/MD studies use the general PUPIL system (Torras et al.). In this case, PUPIL provides automated interoperation of the MNDO Transfer Hamiltonian QM code (Taylor et al.) and a locally written MD code. Embedding of the QM-forces domain is via the scheme of Mallik et al. Work supported by NSF ITR award DMR-0325553.

On the structure of contact binaries. I - The contact discontinuity

NASA Technical Reports Server (NTRS)

Shu, F. H.; Lubow, S. H.; Anderson, L.

1976-01-01

The problem of the interior structure of contact binaries is reviewed, and a simple resolution of the difficulties which plague the theory is suggested. It is proposed that contact binaries contain a contact discontinuity between the lower surface of the common envelope and the Roche lobe of the cooler star. This discontinuity is maintained against thermal diffusion by fluid flow, and the transition layer is thin to the extent that the dynamical time scale is short in comparison with the thermal time scale. The idealization that the transition layer has infinitesimal thickness allows a simple formulation of the structure equations which are closed by appropriate jump conditions across the discontinuity. The further imposition of the standard boundary conditions suffices to define a unique model for the system once the chemical composition, the masses of the two stars, and the orbital separation are specified.

Applying Taguchi design and large-scale strategy for mycosynthesis of nano-silver from endophytic Trichoderma harzianum SYA.F4 and its application against phytopathogens

NASA Astrophysics Data System (ADS)

El-Moslamy, Shahira H.; Elkady, Marwa F.; Rezk, Ahmed H.; Abdel-Fattah, Yasser R.

2017-03-01

Development of reliable and low-cost requirement for large-scale eco-friendly biogenic synthesis of metallic nanoparticles is an important step for industrial applications of bionanotechnology. In the present study, the mycosynthesis of spherical nano-Ag (12.7 ± 0.8 nm) from extracellular filtrate of local endophytic T. harzianum SYA.F4 strain which have interested mixed bioactive metabolites (alkaloids, flavonoids, tannins, phenols, nitrate reductase (320 nmol/hr/ml), carbohydrate (25 μg/μl) and total protein concentration (2.5 g/l) was reported. Industrial mycosynthesis of nano-Ag can be induced with different characters depending on the fungal cultivation and physical conditions. Taguchi design was applied to improve the physicochemical conditions for nano-Ag production, and the optimum conditions which increased its mass weight 3 times larger than a basal condition were as follows: AgNO3 (0.01 M), diluted reductant (10 v/v, pH 5) and incubated at 30 °C, 200 rpm for 24 hr. Kinetic conversion rates in submerged batch cultivation in 7 L stirred tank bioreactor on using semi-defined cultivation medium was as follows: the maximum biomass production (Xmax) and maximum nano-Ag mass weight (Pmax) calculated (60.5 g/l and 78.4 g/l respectively). The best nano-Ag concentration that formed large inhibition zones was 100 μg/ml which showed against A.alternate (43 mm) followed by Helminthosporium sp. (35 mm), Botrytis sp. (32 mm) and P. arenaria (28 mm).

Micro- and Nano-scale Technologies for Delivery into Adherent Cells

PubMed Central

Kang, Wonmo; McNaughton, Rebecca L.; Espinosa, Horacio D.

2016-01-01

process will require the ability to accurately monitor the sequence of intracellular events, within individual cells, in a non-destructive manner. In addition, neuronal maturation is influenced by interactions with surrounding cells and with extracellular matrix, so it is necessary to be able to simultaneously monitor events occurring in multiple cells that are interacting with each other and with the matrix. While the requirements are challenging, these experimental capabilities would provide unprecedented insight into the determinants of both the timing of cellular processes and their phenotype, the principles of cell heterogeneity, and the role of cell-cell communication in homogeneous cell populations and co-cultures. Because most cells adhere to a substrate or to other cells during their growth or differentiation [1], it is advantageous for new technologies to be capable of accessing adhered cells to avoid the need to disrupt cell processes by suspension and replating. Several technologies for studying adhered cells are currently being developed, and due to the need for individual cell access and non-destructive probing, micro- and nano-technologies are a natural choice because they interact with cells at the appropriate length scale, reduce the working volume of expensive reagents, require less time and space for replicates, allow for automation and integration of sequential analyses, enable portability, and reduce waste [2, 3]. Here we present an overview of recently developed micro- and nano-tools, with a focus on trends in intracellular delivery for in vitro studies of adhered cells, and highlight major advantages/disadvantages of these technologies with respect to features such as individual cell selectivity, spatial resolution, non-destructive cell analysis, and potential for high throughput or automation. Finally, we discuss the exciting promise for these technologies to cause a paradigm shift in biological research by providing methods to study cells over

Imaging surface contacts: Power law contact distributions and contact stresses in quartz, calcite, glass and acrylic plastic

USGS Publications Warehouse

Dieterich, J.H.; Kilgore, B.D.

1996-01-01

A procedure has been developed to obtain microscope images of regions of contact between roughened surfaces of transparent materials, while the surfaces are subjected to static loads or undergoing frictional slip. Static loading experiments with quartz, calcite, soda-lime glass and acrylic plastic at normal stresses to 30 MPa yield power law distributions of contact areas from the smallest contacts that can be resolved (3.5 ??m2) up to a limiting size that correlates with the grain size of the abrasive grit used to roughen the surfaces. In each material, increasing normal stress results in a roughly linear increase of the real area of contact. Mechanisms of contact area increase are by growth of existing contacts, coalescence of contacts and appearance of new contacts. Mean contacts stresses are consistent with the indentation strength of each material. Contact size distributions are insensitive to normal stress indicating that the increase of contact area is approximately self-similar. The contact images and contact distributions are modeled using simulations of surfaces with random fractal topographies. The contact process for model fractal surfaces is represented by the simple expedient of removing material at regions where surface irregularities overlap. Synthetic contact images created by this approach reproduce observed characteristics of the contacts and demonstrate that the exponent in the power law distributions depends on the scaling exponent used to generate the surface topography.

Surface conductance of graphene from non-contact resonant cavity.

PubMed

Obrzut, Jan; Emiroglu, Caglar; Kirillov, Oleg; Yang, Yanfei; Elmquist, Randolph E

2016-06-01

A method is established to reliably determine surface conductance of single-layer or multi-layer atomically thin nano-carbon graphene structures. The measurements are made in an air filled standard R100 rectangular waveguide configuration at one of the resonant frequency modes, typically at TE 103 mode of 7.4543 GHz. Surface conductance measurement involves monitoring a change in the quality factor of the cavity as the specimen is progressively inserted into the cavity in quantitative correlation with the specimen surface area. The specimen consists of a nano-carbon-layer supported on a low loss dielectric substrate. The thickness of the conducting nano-carbon layer does not need to be explicitly known, but it is assumed that the lateral dimension is uniform over the specimen area. The non-contact surface conductance measurements are illustrated for a typical graphene grown by chemical vapor deposition process, and for a high quality monolayer epitaxial graphene grown on silicon carbide wafers for which we performed non-gated quantum Hall resistance measurements. The sequence of quantized transverse Hall resistance at the Landau filling factors ν = ±6 and ±2, and the absence of the Hall plateau at ν = 4 indicate that the epitaxially grown graphene is a high quality mono-layer. The resonant microwave cavity measurement is sensitive to the surface and bulk conductivity, and since no additional processing is required, it preserves the integrity of the conductive graphene layer. It allows characterization with high speed, precision and efficiency, compared to transport measurements where sample contacts must be defined and applied in multiple processing steps.

Optical Detection and Sizing of Single Nano-Particles Using Continuous Wetting Films

PubMed Central

Hennequin, Yves; McLeod, Euan; Mudanyali, Onur; Migliozzi, Daniel; Ozcan, Aydogan; Dinten, Jean-Marc

2013-01-01

The physical interaction between nano-scale objects and liquid interfaces can create unique optical properties, enhancing the signatures of the objects with sub-wavelength features. Here we show that the evaporation on a wetting substrate of a polymer solution containing sub-micrometer or nano-scale particles creates liquid micro-lenses that arise from the local deformations of the continuous wetting film. These micro-lenses have properties similar to axicon lenses that are known to create beams with a long depth of focus. This enhanced depth of focus allows detection of single nanoparticles using a low magnification microscope objective lens, achieving a relatively wide field-of-view, while also lifting the constraints on precise focusing onto the object plane. Hence, by creating these liquid axicon lenses through spatial deformations of a continuous thin wetting film, we transfer the challenge of imaging individual nano-particles to detecting the light focused by these lenses. As a proof of concept, we demonstrate the detection and sizing of single nano-particles (100 and 200 nm), CpGV granuloviruses as well as Staphylococcus epidermidis bacteria over a wide field of view of e.g., 5.10×3.75 mm2 using a ×5 objective lens with a numerical aperture of 0.15. In addition to conventional lens-based microscopy, this continuous wetting film based approach is also applicable to lensfree computational on-chip imaging, which can be used to detect single nano-particles over a large field-of-view of e.g., >20-30 mm2. These results could be especially useful for high-throughput field-analysis of nano-scale objects using compact and cost-effective microscope designs. PMID:23889001

Bi-stage time evolution of nano-morphology on inductively coupled plasma etched fused silica surface caused by surface morphological transformation

NASA Astrophysics Data System (ADS)

Jiang, Xiaolong; Zhang, Lijuan; Bai, Yang; Liu, Ying; Liu, Zhengkun; Qiu, Keqiang; Liao, Wei; Zhang, Chuanchao; Yang, Ke; Chen, Jing; Jiang, Yilan; Yuan, Xiaodong

2017-07-01

In this work, we experimentally investigate the surface nano-roughness during the inductively coupled plasma etching of fused silica, and discover a novel bi-stage time evolution of surface nano-morphology. At the beginning, the rms roughness, correlation length and nano-mound dimensions increase linearly and rapidly with etching time. At the second stage, the roughening process slows down dramatically. The switch of evolution stage synchronizes with the morphological change from dual-scale roughness comprising long wavelength underlying surface and superimposed nano-mounds to one scale of nano-mounds. A theoretical model based on surface morphological change is proposed. The key idea is that at the beginning, etched surface is dual-scale, and both larger deposition rate of etch inhibitors and better plasma etching resistance at the surface peaks than surface valleys contribute to the roughness development. After surface morphology transforming into one-scale, the difference of plasma resistance between surface peaks and valleys vanishes, thus the roughening process slows down.

Effects of nano-scaled fish bone on the gelation properties of Alaska pollock surimi.

PubMed

Yin, Tao; Park, Jae W

2014-05-01

Gelation properties of Alaska pollock surimi as affected by addition of nano-scaled fish bone (NFB) at different levels (0%, 0.1%, 0.25%, 0.5%, 1% and 2%) were investigated. Breaking force and penetration distance of surimi gels after setting increased significantly as NFB concentration increased up to 1%. The first peak temperature and value of storage modulus (G'), which is known to relate to the unfolding and aggregation of light meromyosin, increased as NFB concentration increased. In addition, 1% NFB treatment demonstrated the highest G' after gelation was completed. The activity of endogenous transglutaminase (TGase) in Alaska pollock surimi increased as NFB calcium concentration increased. The intensity of myosin heavy chain cross-links also increased as NFB concentration increased indicating the formation of more ε-(γ-glutamyl) lysine covalent bond by endogenous TGase and calcium ions from NFB. Copyright © 2013 Elsevier Ltd. All rights reserved.

Full-field x-ray nano-imaging at SSRF

NASA Astrophysics Data System (ADS)

Deng, Biao; Ren, Yuqi; Wang, Yudan; Du, Guohao; Xie, Honglan; Xiao, Tiqiao

2013-09-01

Full field X-ray nano-imaging focusing on material science is under developing at SSRF. A dedicated full field X-ray nano-imaging beamline based on bending magnet will be built in the SSRF phase-II project. The beamline aims at the 3D imaging of the nano-scale inner structures. The photon energy range is of 5-14keV. The design goals with the field of view (FOV) of 20μm and a spatial resolution of 20nm are proposed at 8 keV, taking a Fresnel zone plate (FZP) with outermost zone width of 25 nm. Futhermore, an X-ray nano-imaging microscope is under developing at the SSRF BL13W beamline, in which a larger FOV will be emphasized. This microscope is based on a beam shaper and a zone plate using both absorption contrast and Zernike phase contrast, with the optimized energy set to 10keV. The detailed design and the progress of the project will be introduced.

Friction and universal contact area law for randomly rough viscoelastic contacts.

PubMed

Scaraggi, M; Persson, B N J

2015-03-18

We present accurate numerical results for the friction force and the contact area for a viscoelastic solid (rubber) in sliding contact with hard, randomly rough substrates. The rough surfaces are self-affine fractal with roughness over several decades in length scales. We calculate the contribution to the friction from the pulsating deformations induced by the substrate asperities. We also calculate how the area of real contact, A(v, p), depends on the sliding speed v and on the nominal contact pressure p, and we show how the contact area for any sliding speed can be obtained from a universal master curve A(p). The numerical results are found to be in good agreement with the predictions of an analytical contact mechanics theory.

Modeling and simulation of electronic structure, material interface and random doping in nano electronic devices

PubMed Central

Chen, Duan; Wei, Guo-Wei

2010-01-01

The miniaturization of nano-scale electronic devices, such as metal oxide semiconductor field effect transistors (MOSFETs), has given rise to a pressing demand in the new theoretical understanding and practical tactic for dealing with quantum mechanical effects in integrated circuits. Modeling and simulation of this class of problems have emerged as an important topic in applied and computational mathematics. This work presents mathematical models and computational algorithms for the simulation of nano-scale MOSFETs. We introduce a unified two-scale energy functional to describe the electrons and the continuum electrostatic potential of the nano-electronic device. This framework enables us to put microscopic and macroscopic descriptions in an equal footing at nano scale. By optimization of the energy functional, we derive consistently-coupled Poisson-Kohn-Sham equations. Additionally, layered structures are crucial to the electrostatic and transport properties of nano transistors. A material interface model is proposed for more accurate description of the electrostatics governed by the Poisson equation. Finally, a new individual dopant model that utilizes the Dirac delta function is proposed to understand the random doping effect in nano electronic devices. Two mathematical algorithms, the matched interface and boundary (MIB) method and the Dirichlet-to-Neumann mapping (DNM) technique, are introduced to improve the computational efficiency of nano-device simulations. Electronic structures are computed via subband decomposition and the transport properties, such as the I-V curves and electron density, are evaluated via the non-equilibrium Green's functions (NEGF) formalism. Two distinct device configurations, a double-gate MOSFET and a four-gate MOSFET, are considered in our three-dimensional numerical simulations. For these devices, the current fluctuation and voltage threshold lowering effect induced by the discrete dopant model are explored. Numerical convergence

Controlled gas-liquid interfacial plasmas for synthesis of nano-bio-carbon conjugate materials

NASA Astrophysics Data System (ADS)

Kaneko, Toshiro; Hatakeyama, Rikizo

2018-01-01

Plasmas generated in contact with a liquid have been recognized to be a novel reactive field in nano-bio-carbon conjugate creation because several new chemical reactions have been yielded at the gas-liquid interface, which were induced by the physical dynamics of non-equilibrium plasmas. One is the ion irradiation to a liquid, which caused the spatially selective dissociation of the liquid and the generation of additive reducing and oxidizing agents, resulting in the spatially controlled synthesis of nanostructures. The other is the electron irradiation to a liquid, which directly enhanced the reduction action at the plasma-liquid interface, resulting in temporally controlled nanomaterial synthesis. Using this novel reaction field, gold nanoparticles with controlled interparticle distance were synthesized using carbon nanotubes as a template. Furthermore, nanoparticle-biomolecule conjugates and nanocarbon-biomolecule conjugates were successfully synthesized by an aqueous-solution contact plasma and an electrolyte plasma, respectively, which were rapid and low-damage processes suitable for nano-bio-carbon conjugate materials.

Mechanical characterization of scalable cellulose nano-fiber based composites made using liquid composite molding process

Treesearch

Bamdad Barari; Thomas K. Ellingham; Issam I. Ghamhia; Krishna M. Pillai; Rani El-Hajjar; Lih-Sheng Turng; Ronald Sabo

2016-01-01

Plant derived cellulose nano-fibers (CNF) are a material with remarkable mechanical properties compared to other natural fibers. However, efforts to produce nano-composites on a large scale using CNF have yet to be investigated. In this study, scalable CNF nano-composites were made from isotropically porous CNF preforms using a freeze drying process. An improvised...

Advanced nano lithography via soft materials-derived and reversible nano-patterning methodology for molding of infrared nano lenses

NASA Astrophysics Data System (ADS)

Park, Jae Hong; Jang, Hyun Ik; Park, Jun Yong; Jeon, Seok Woo; Kim, Woo Choong; Kim, Hee Yeoun; Ahn, Chi Won

2015-03-01

The methodology suggested in this research provides the great possibility of creating nanostructures composed of various materials, such as soft polymer, hard polymer, and metal, as well as Si. Such nanostructures are required for a vast range of optical and display devices, photonic components, physical devices, energy devices including electrodes of secondary batteries, fuel cells, solar cells, and energy harvesters, biological devices including biochips, biomimetic or biosimilar structured devices, and mechanical devices including micro- or nano-scale sensors and actuators.

Modeling Thermal Contact Resistance

NASA Technical Reports Server (NTRS)

Kittel, Peter; Sperans, Joel (Technical Monitor)

1994-01-01

One difficulty in using cryocoolers is making good thermal contact between the cooler and the instrument being cooled. The connection is often made through a bolted joint. The temperature drop associated with this joint has been the subject of many experimental and theoretical studies. The low temperature behavior of dry joints have shown some anomalous dependence on the surface condition of the mating parts. There is also some doubts on how well one can extrapolate from the test samples to predicting the performance of a real system. Both finite element and analytic models of a simple contact system have been developed. The model assumes (a) the contact is dry (contact limited to a small portion of the total available area and the spaces in-between the actual contact patches are perfect insulators), (b) contacts are clean (conductivity of the actual contact is the same as the bulk), (c) small temperature gradients (the bulk conductance may be assumed to be temperature independent), (d) the absolute temperature is low (thermal radiation effects are ignored), and (e) the dimensions of the nominal contact area are small compared to the thickness of the bulk material (the contact effects are localized near the contact). The models show that in the limit of actual contact area much less than the nominal area (a much less than A), that the excess temperature drop due to a single point of contact scales as a(exp -1/2). This disturbance only extends a distance approx. A(exp 1/2) into the bulk material. A group of identical contacts will result in an excess temperature drop that scales as n(exp -1/2), where n is the number of contacts and n dot a is constant. This implies that flat rough surfaces will have a lower excess temperature drop than flat polished surfaces.

Distinct modes of recruitment of the CCR4-NOT complex by Drosophila and vertebrate Nanos.

PubMed

Raisch, Tobias; Bhandari, Dipankar; Sabath, Kevin; Helms, Sigrun; Valkov, Eugene; Weichenrieder, Oliver; Izaurralde, Elisa

2016-05-02

Nanos proteins repress the expression of target mRNAs by recruiting effector complexes through non-conserved N-terminal regions. In vertebrates, Nanos proteins interact with the NOT1 subunit of the CCR4-NOT effector complex through a NOT1 interacting motif (NIM), which is absent in Nanos orthologs from several invertebrate species. Therefore, it has remained unclear whether the Nanos repressive mechanism is conserved and whether it also involves direct interactions with the CCR4-NOT deadenylase complex in invertebrates. Here, we identify an effector domain (NED) that is necessary for the Drosophila melanogaster (Dm) Nanos to repress mRNA targets. The NED recruits the CCR4-NOT complex through multiple and redundant binding sites, including a central region that interacts with the NOT module, which comprises the C-terminal domains of NOT1-3. The crystal structure of the NED central region bound to the NOT module reveals an unanticipated bipartite binding interface that contacts NOT1 and NOT3 and is distinct from the NIM of vertebrate Nanos. Thus, despite the absence of sequence conservation, the N-terminal regions of Nanos proteins recruit CCR4-NOT to assemble analogous repressive complexes. © 2016 The Authors. Published under the terms of the CC BY NC ND 4.0 license.

Murine liver damage caused by exposure to nano-titanium dioxide

NASA Astrophysics Data System (ADS)

Hong, Jie; Zhang, Yu-Qing

2016-03-01

Due to its unique physiochemical properties, nano-titanium dioxide (nano-TiO2) is widely used in all aspects of people’s daily lives, bringing it into increasing contact with humans. Thus, this material’s security issues for humans have become a heavily researched subject. Nano-TiO2 can enter the body through the mouth, skin, respiratory tract or in other ways, after which it enters the blood circulation and is deposited in the liver, changing biochemical indicators and causing liver inflammation. Meanwhile, the light sensitivity of these nanoparticles allows them to become media-generating reactive oxygen species (ROS), causing an imbalance between oxidation and anti-oxidation that leads to oxidative stress and liver damage. Nano-TiO2 can be transported into cells via phagocytosis, where the nanoparticles bind to the mitochondrial membrane, resulting in the disintegration of the membrane and the electron transport chain within the mitochondria. Thus, more ROS are produced. Nano-TiO2 can also enter the nucleus, where it can directly embed into or indirectly affect DNA, thereby causing DNA breakage or affecting gene expression. These effects include increased mRNA and protein expression levels of inflammation-related factors and decreased mRNA and protein expression levels of IκB and IL-2, resulting in inflammation. Long-term inflammation of the liver causes HSC cell activation, and extracellular matrix (ECM) deposition is promoted by multiple signalling pathways, resulting in liver fibrosis. In this paper, the latest progress on murine liver injury induced by environmental TiO2 is systematically described. The toxicity of nano-TiO2 also depends on size, exposure time, surface properties, dosage, administration route, and its surface modification. Therefore, its toxic effects in humans should be studied in greater depth. This paper also provides useful reference information regarding the safe use of nano-TiO2 in the future.

Look@NanoSIMS--a tool for the analysis of nanoSIMS data in environmental microbiology.

PubMed

Polerecky, Lubos; Adam, Birgit; Milucka, Jana; Musat, Niculina; Vagner, Tomas; Kuypers, Marcel M M

2012-04-01

We describe an open-source freeware programme for high throughput analysis of nanoSIMS (nanometre-scale secondary ion mass spectrometry) data. The programme implements basic data processing and analytical functions, including display and drift-corrected accumulation of scanned planes, interactive and semi-automated definition of regions of interest (ROIs), and export of the ROIs' elemental and isotopic composition in graphical and text-based formats. Additionally, the programme offers new functions that were custom-designed to address the needs of environmental microbiologists. Specifically, it allows manual and automated classification of ROIs based on the information that is derived either from the nanoSIMS dataset itself (e.g. from labelling achieved by halogen in situ hybridization) or is provided externally (e.g. as a fluorescence in situ hybridization image). Moreover, by implementing post-processing routines coupled to built-in statistical tools, the programme allows rapid synthesis and comparative analysis of results from many different datasets. After validation of the programme, we illustrate how these new processing and analytical functions increase flexibility, efficiency and depth of the nanoSIMS data analysis. Through its custom-made and open-source design, the programme provides an efficient, reliable and easily expandable tool that can help a growing community of environmental microbiologists and researchers from other disciplines process and analyse their nanoSIMS data. © 2012 Society for Applied Microbiology and Blackwell Publishing Ltd.

Nano-imprint gold grating as refractive index sensor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumari, Sudha; Mohapatra, Saswat; Moirangthem, Rakesh S.

Large scale of fabrication of plasmonic nanostructures has been a challenging task due to time consuming process and requirement of expensive nanofabrication tools such as electron beam lithography system, focused ion beam system, and extreme UV photolithography system. Here, we present a cost-effective fabrication technique so called soft nanoimprinting to fabricate nanostructures on the larger sample area. In our fabrication process, a commercially available optical DVD disc was used as a template which was imprinted on a polymer glass substrate to prepare 1D polymer nano-grating. A homemade nanoimprinting setup was used in this fabrication process. Further, a label-free refractive indexmore » sensor was developed by utilizing the properties of surface plasmon resonance (SPR) of a gold coated 1D polymer nano-grating. Refractive index sensing was tested by exposing different solutions of glycerol-water mixture on the surface of gold nano-grating. The calculated bulk refractive index sensitivity was found to be 751nm/RIU. We believed that our proposed SPR sensor could be a promising candidate for developing low-cost refractive index sensor with high sensitivity on a large scale.« less

Facile fabrication of super-hydrophobic nano-needle arrays via breath figures method.

PubMed

Kim, Jiseok; Lew, Brian; Kim, Woo Soo

2011-12-06

Super-hydrophobic surfaces which have been fabricated by various methods such as photolithography, chemical treatment, self-assembly, and imprinting have gained enormous attention in recent years. Especially 2D arrays of nano-needles have been shown to have super-hydrophobicity due to their sharp surface roughness. These arrays can be easily generated by removing the top portion of the honeycomb films prepared by the breath figures method. The hydrophilic block of an amphiphilic polymer helps in the fabrication of the nano-needle arrays through the production of well-ordered honeycomb films and good adhesion of the film to a substrate. Anisotropic patterns with water wettability difference can be useful for patterning cells and other materials using their selective growth on the hydrophilic part of the pattern. However, there has not been a simple way to generate patterns with highly different wettability. Mechanical stamping of the nano-needle array with a polyurethane stamp might be the simplest way to fabricate patterns with wettability difference. In this study, super-hydrophobic nano-needle arrays were simply fabricated by removing the top portion of the honeycomb films. The maximum water contact angle obtained with the nano-needle array was 150°. By controlling the pore size and the density of the honeycomb films, the height, width, and density of nano-needle arrays were determined. Anisotropic patterns with different wettability were fabricated by simply pressing the nano-needle array at ambient temperature with polyurethane stamps which were flexible but tough. Mechanical stamping of nano-needle arrays with micron patterns produced hierarchical super-hydrophobic structures.PACS: 05.70.Np, 68.55.am, 68.55.jm.

Facile fabrication of super-hydrophobic nano-needle arrays via breath figures method

PubMed Central

2011-01-01

Super-hydrophobic surfaces which have been fabricated by various methods such as photolithography, chemical treatment, self-assembly, and imprinting have gained enormous attention in recent years. Especially 2D arrays of nano-needles have been shown to have super-hydrophobicity due to their sharp surface roughness. These arrays can be easily generated by removing the top portion of the honeycomb films prepared by the breath figures method. The hydrophilic block of an amphiphilic polymer helps in the fabrication of the nano-needle arrays through the production of well-ordered honeycomb films and good adhesion of the film to a substrate. Anisotropic patterns with water wettability difference can be useful for patterning cells and other materials using their selective growth on the hydrophilic part of the pattern. However, there has not been a simple way to generate patterns with highly different wettability. Mechanical stamping of the nano-needle array with a polyurethane stamp might be the simplest way to fabricate patterns with wettability difference. In this study, super-hydrophobic nano-needle arrays were simply fabricated by removing the top portion of the honeycomb films. The maximum water contact angle obtained with the nano-needle array was 150°. By controlling the pore size and the density of the honeycomb films, the height, width, and density of nano-needle arrays were determined. Anisotropic patterns with different wettability were fabricated by simply pressing the nano-needle array at ambient temperature with polyurethane stamps which were flexible but tough. Mechanical stamping of nano-needle arrays with micron patterns produced hierarchical super-hydrophobic structures. PACS: 05.70.Np, 68.55.am, 68.55.jm PMID:22145673

Applying Taguchi design and large-scale strategy for mycosynthesis of nano-silver from endophytic Trichoderma harzianum SYA.F4 and its application against phytopathogens

PubMed Central

EL-Moslamy, Shahira H.; Elkady, Marwa F.; Rezk, Ahmed H.; Abdel-Fattah, Yasser R.

2017-01-01

Development of reliable and low-cost requirement for large-scale eco-friendly biogenic synthesis of metallic nanoparticles is an important step for industrial applications of bionanotechnology. In the present study, the mycosynthesis of spherical nano-Ag (12.7 ± 0.8 nm) from extracellular filtrate of local endophytic T. harzianum SYA.F4 strain which have interested mixed bioactive metabolites (alkaloids, flavonoids, tannins, phenols, nitrate reductase (320 nmol/hr/ml), carbohydrate (25 μg/μl) and total protein concentration (2.5 g/l) was reported. Industrial mycosynthesis of nano-Ag can be induced with different characters depending on the fungal cultivation and physical conditions. Taguchi design was applied to improve the physicochemical conditions for nano-Ag production, and the optimum conditions which increased its mass weight 3 times larger than a basal condition were as follows: AgNO3 (0.01 M), diluted reductant (10 v/v, pH 5) and incubated at 30 °C, 200 rpm for 24 hr. Kinetic conversion rates in submerged batch cultivation in 7 L stirred tank bioreactor on using semi-defined cultivation medium was as follows: the maximum biomass production (Xmax) and maximum nano-Ag mass weight (Pmax) calculated (60.5 g/l and 78.4 g/l respectively). The best nano-Ag concentration that formed large inhibition zones was 100 μg/ml which showed against A.alternate (43 mm) followed by Helminthosporium sp. (35 mm), Botrytis sp. (32 mm) and P. arenaria (28 mm). PMID:28349997

Spatio-temporal behaviour of atomic-scale tribo-ceramic films in adaptive surface engineered nano-materials.

PubMed

Fox-Rabinovich, G; Kovalev, A; Veldhuis, S; Yamamoto, K; Endrino, J L; Gershman, I S; Rashkovskiy, A; Aguirre, M H; Wainstein, D L

2015-03-05

Atomic-scale, tribo-ceramic films associated with dissipative structures formation are discovered under extreme frictional conditions which trigger self-organization. For the first time, we present an actual image of meta-stable protective tribo-ceramics within thicknesses of a few atomic layers. A mullite and sapphire structure predominates in these phases. They act as thermal barriers with an amazing energy soaking/dissipating capacity. Less protective tribo-films cannot sustain in these severe conditions and rapidly wear out. Therefore, a functional hierarchy is established. The created tribo-films act in synergy, striving to better adapt themselves to external stimuli. Under a highly complex structure and non-equilibrium state, the upcoming generation of adaptive surface engineered nano-multilayer materials behaves like intelligent systems - capable of generating, with unprecedented efficiency, the necessary tribo-films to endure an increasingly severe environment.

Spatio-temporal behaviour of atomic-scale tribo-ceramic films in adaptive surface engineered nano-materials

PubMed Central

Fox-Rabinovich, G.; Kovalev, A.; Veldhuis, S.; Yamamoto, K.; Endrino, J. L.; Gershman, I. S.; Rashkovskiy, A.; Aguirre, M. H.; Wainstein, D. L.

2015-01-01

Atomic-scale, tribo-ceramic films associated with dissipative structures formation are discovered under extreme frictional conditions which trigger self-organization. For the first time, we present an actual image of meta-stable protective tribo-ceramics within thicknesses of a few atomic layers. A mullite and sapphire structure predominates in these phases. They act as thermal barriers with an amazing energy soaking/dissipating capacity. Less protective tribo-films cannot sustain in these severe conditions and rapidly wear out. Therefore, a functional hierarchy is established. The created tribo-films act in synergy, striving to better adapt themselves to external stimuli. Under a highly complex structure and non-equilibrium state, the upcoming generation of adaptive surface engineered nano-multilayer materials behaves like intelligent systems - capable of generating, with unprecedented efficiency, the necessary tribo-films to endure an increasingly severe environment. PMID:25740153

Sprayable superhydrophobic nano-chains coating with continuous self-jumping of dew and melting frost

PubMed Central

Wang, Shanlin; Zhang, Wenwen; Yu, Xinquan; Liang, Caihua; Zhang, Youfa

2017-01-01

Spontaneous movement of condensed matter provides a new insight to efficiently improve condensation heat transfer on superhydrophobic surface. However, very few reports have shown the jumping behaviors on the sprayable superhydrophobic coatings. Here, we developed a sprayable silica nano-porous coating assembled by fluorinated nano-chains to survey the condensates’ dynamics. The dewdrops were continuously removed by self- and/or trigger-propelling motion due to abundant nano-pores from random multilayer stacking of nano-chains. In comparison, the dewdrops just could be slipped under the gravity effect on lack of nano-pores coatings stacked by silica nano-spheres and nano-aggregates. More interestingly, the spontaneous jumping effect also occurred on micro-scale frost crystals under the defrosting process on nano-chains coating surfaces. Different from self-jumping of dewdrops motion, the propelling force of frost crystals were provided by a sudden increase of the pressure under the frost crystal. PMID:28074938

Investigation of the Structural, Electrical, and Optical Properties of the Nano-Scale GZO Thin Films on Glass and Flexible Polyimide Substrates

PubMed Central

Wang, Fang-Hsing; Chen, Kun-Neng; Hsu, Chao-Ming; Liu, Min-Chu; Yang, Cheng-Fu

2016-01-01

In this study, Ga2O3-doped ZnO (GZO) thin films were deposited on glass and flexible polyimide (PI) substrates at room temperature (300 K), 373 K, and 473 K by the radio frequency (RF) magnetron sputtering method. After finding the deposition rate, all the GZO thin films with a nano-scale thickness of about 150 ± 10 nm were controlled by the deposition time. X-ray diffraction patterns indicated that the GZO thin films were not amorphous and all exhibited the (002) peak, and field emission scanning electron microscopy showed that only nano-scale particles were observed. The dependences of the structural, electrical, and optical properties of the GZO thin films on different deposition temperatures and substrates were investigated. X-ray photoemission spectroscopy (XPS) was used to measure the elemental composition at the chemical and electronic states of the GZO thin films deposited on different substrates, which could be used to clarify the mechanism of difference in electrical properties of the GZO thin films. In this study, the XPS binding energy spectra of Ga2p3/2 and Ga2p1/2 peaks, Zn2p3/2 and Zn2p1/2 peaks, the Ga3d peak, and O1s peaks for GZO thin films on glass and PI substrates were well compared. PMID:28335216

Protein Translocation into the Intermembrane Space and Matrix of Mitochondria: Mechanisms and Driving Forces.

PubMed

Backes, Sandra; Herrmann, Johannes M

2017-01-01

Mitochondria contain two aqueous subcompartments, the matrix and the intermembrane space (IMS). The matrix is enclosed by both the inner and outer mitochondrial membranes, whilst the IMS is sandwiched between the two. Proteins of the matrix are synthesized in the cytosol as preproteins, which contain amino-terminal matrix targeting sequences that mediate their translocation through translocases embedded in the outer and inner membrane. For these proteins, the translocation reaction is driven by the import motor which is part of the inner membrane translocase. The import motor employs matrix Hsp70 molecules and ATP hydrolysis to ratchet proteins into the mitochondrial matrix. Most IMS proteins lack presequences and instead utilize the IMS receptor Mia40, which facilitates their translocation across the outer membrane in a reaction that is coupled to the formation of disulfide bonds within the protein. This process requires neither ATP nor the mitochondrial membrane potential. Mia40 fulfills two roles: First, it acts as a holdase, which is crucial in the import of IMS proteins and second, it functions as a foldase, introducing disulfide bonds into newly imported proteins, which induces and stabilizes their natively folded state. For several Mia40 substrates, oxidative folding is an essential prerequisite for their assembly into oligomeric complexes. Interestingly, recent studies have shown that the two functions of Mia40 can be experimentally separated from each other by the use of specific mutants, hence providing a powerful new way to dissect the different physiological roles of Mia40. In this review we summarize the current knowledge relating to the mitochondrial matrix-targeting and the IMS-targeting/Mia40 pathway. Moreover, we discuss the mechanistic properties by which the mitochondrial import motor on the one hand and Mia40 on the other, drive the translocation of their substrates into the organelle. We propose that the lateral diffusion of Mia40 in the inner

Thermal, Microchannel, and Immersed Boundary Extension Validation for the Lattice-Boltzmann Method: Report 2 in Discrete Nano Scale Mechanics and Simulations Series

DTIC Science & Technology

2017-07-01

Lattice Boltzmann Method continues to garner interest in fluids research , particularly with its ability to accurately simulate laminar flows in the...Lattice- Boltzmann Method Report 2 in “Discrete Nano-Scale Mechanics and Simulations” Series In fo rm at io n Te ch no lo gy L ab or at or y...William P. England and Jeffrey B. Allen July 2017 Approved for public release; distribution is unlimited. The U.S. Army Engineer Research and

Carbon nanotube thin film strain sensor models assembled using nano- and micro-scale imaging

NASA Astrophysics Data System (ADS)

Lee, Bo Mi; Loh, Kenneth J.; Yang, Yuan-Sen

2017-07-01

Nanomaterial-based thin films, particularly those based on carbon nanotubes (CNT), have brought forth tremendous opportunities for designing next-generation strain sensors. However, their strain sensing properties can vary depending on fabrication method, post-processing treatment, and types of CNTs and polymers employed. The objective of this study was to derive a CNT-based thin film strain sensor model using inputs from nano-/micro-scale experimental measurements of nanotube physical properties. This study began with fabricating ultra-low-concentration CNT-polymer thin films, followed by imaging them using atomic force microscopy. Image processing was employed for characterizing CNT dispersed shapes, lengths, and other physical attributes, and results were used for building five different types of thin film percolation-based models. Numerical simulations were conducted to assess how the morphology of dispersed CNTs in its 2D matrix affected bulk film electrical and electromechanical (strain sensing) properties. The simulation results showed that CNT morphology had a significant impact on strain sensing performance.

Femtosecond pulsed laser processing of electronic materials: Fundamentals and micro/nano-scale applications

NASA Astrophysics Data System (ADS)

Choi, Tae-Youl

ultrashort laser pulse accompanied by the pre-pulse induces air breakdown that can be detrimental to materials processing. A time-resolved pump-and-probe experiment provides distinct evidence for the occurrence of an air plasma and air breakdown. This highly nonlinear phenomenon takes place before the commencement of the ablation process, which is traced beyond elapsed time of the order of 10 ps with respect to the ablating pulse. The nonlinear refractive index of the generated air plasma is calculated as a function of electron density. The self-focusing of the main pulse is identified by the third order nonlinear susceptibility. A crystalline silicon sample is subjected to two optically separated ultra-fast laser pulses of full-width-half-maximum (FWHM) duration of about 80 femtoseconds. These pulses are delivered at wavelength, lambda = 800 nm. Femtosecond-resolved imaging pump-and-probe experiments in reflective and Schlieren configurations have been performed to investigate plasma dynamics and shock wave propagation during the sample ablation process. By using a diffractive optical element (DOE) for beam shaping, microchannels were fabricated. A super-long working distance objective lens was used to machine silicon materials in the sub-micrometer scale. As an extension of micro-machining, the finite difference time domain (FDTD) method is used to assess the feasibility of using near-field distribution of laser light. Gold coated films were machined with nano-scale dimensions and characterized with atomic force microscopy (AFM).

An approximate JKR solution for a general contact, including rough contacts

NASA Astrophysics Data System (ADS)

Ciavarella, M.

2018-05-01

In the present note, we suggest a simple closed form approximate solution to the adhesive contact problem under the so-called JKR regime. The derivation is based on generalizing the original JKR energetic derivation assuming calculation of the strain energy in adhesiveless contact, and unloading at constant contact area. The underlying assumption is that the contact area distributions are the same as under adhesiveless conditions (for an appropriately increased normal load), so that in general the stress intensity factors will not be exactly equal at all contact edges. The solution is simply that the indentation is δ =δ1 -√{ 2 wA‧ /P″ } where w is surface energy, δ1 is the adhesiveless indentation, A‧ is the first derivative of contact area and P‧‧ the second derivative of the load with respect to δ1. The solution only requires macroscopic quantities, and not very elaborate local distributions, and is exact in many configurations like axisymmetric contacts, but also sinusoidal waves contact and correctly predicts some features of an ideal asperity model used as a test case and not as a real description of a rough contact problem. The solution permits therefore an estimate of the full solution for elastic rough solids with Gaussian multiple scales of roughness, which so far was lacking, using known adhesiveless simple results. The result turns out to depend only on rms amplitude and slopes of the surface, and as in the fractal limit, slopes would grow without limit, tends to the adhesiveless result - although in this limit the JKR model is inappropriate. The solution would also go to adhesiveless result for large rms amplitude of roughness hrms, irrespective of the small scale details, and in agreement with common sense, well known experiments and previous models by the author.

Microbial contamination of contact lenses after scaling and root planing using ultrasonic scalers with and without protective eyewear: A clinical and microbiological study.

PubMed

Afzha, Rooh; Chatterjee, Anirban; Subbaiah, Shobha Krishna; Pradeep, Avani Rangaraju

2016-01-01

Ultrasonic scaler is a preferential treatment modality among the clinicians. However, the aerosol/splatter generated is a concern for patients and practitioners. Therefore, the purpose of this study was to evaluate contamination of contact lenses of the dentist after scaling and root planing using ultrasonic scalers with and without protective eyewear. Thirty patients were randomly selected for scaling and root planing and divided into 2 groups of 15 each. Group A - dentist wearing contact lenses and protective eyewear. Group B - dentist wearing only contact lenses. After scaling and root planing using ultrasonic scalers, the lenses were subjected to culture and 16S rRNA (16S ribosomal RNA) gene sequencing. In Group A - 15 out of thirty samples were contaminated, in Group B - all the thirty samples were contaminated. Most of the samples showed Gram-positive bacteria and 5 samples were contaminated with fungi. 16S rRNA gene sequencing of forty contaminated samples showed that 31 were contaminated with Streptococcus mutans and 9 with Staphylococcus aureus. Keeping in mind the limitation of the study for the absence of negative control, we would like to conclude that dental practitioners should better avoid contact lenses in a dental setup because of the risk of contamination of the contact lenses from the various dental procedures which can produce aerosol/splatter and if worn, it is recommended to wear protective eyewear.

Pore-scale modeling of moving contact line problems in immiscible two-phase flow

NASA Astrophysics Data System (ADS)

Kucala, Alec; Noble, David; Martinez, Mario

2016-11-01

Accurate modeling of moving contact line (MCL) problems is imperative in predicting capillary pressure vs. saturation curves, permeability, and preferential flow paths for a variety of applications, including geological carbon storage (GCS) and enhanced oil recovery (EOR). Here, we present a model for the moving contact line using pore-scale computational fluid dynamics (CFD) which solves the full, time-dependent Navier-Stokes equations using the Galerkin finite-element method. The MCL is modeled as a surface traction force proportional to the surface tension, dependent on the static properties of the immiscible fluid/solid system. We present a variety of verification test cases for simple two- and three-dimensional geometries to validate the current model, including threshold pressure predictions in flows through pore-throats for a variety of wetting angles. Simulations involving more complex geometries are also presented to be used in future simulations for GCS and EOR problems. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Environmental risk assessment of engineered nano-SiO2 , nano iron oxides, nano-CeO2 , nano-Al2 O3 , and quantum dots.

PubMed

Wang, Yan; Nowack, Bernd

2018-05-01

Many research studies have endeavored to investigate the ecotoxicological hazards of engineered nanomaterials (ENMs). However, little is known regarding the actual environmental risks of ENMs, combining both hazard and exposure data. The aim of the present study was to quantify the environmental risks for nano-Al 2 O 3 , nano-SiO 2 , nano iron oxides, nano-CeO 2 , and quantum dots by comparing the predicted environmental concentrations (PECs) with the predicted-no-effect concentrations (PNECs). The PEC values of these 5 ENMs in freshwaters in 2020 for northern Europe and southeastern Europe were taken from a published dynamic probabilistic material flow analysis model. The PNEC values were calculated using probabilistic species sensitivity distribution (SSD). The order of the PNEC values was quantum dots < nano-CeO 2  < nano iron oxides < nano-Al 2 O 3  < nano-SiO 2 . The risks posed by these 5 ENMs were demonstrated to be in the reverse order: nano-Al 2 O 3  > nano-SiO 2  > nano iron oxides > nano-CeO 2  > quantum dots. However, all risk characterization values are 4 to 8 orders of magnitude lower than 1, and no risk was therefore predicted for any of the investigated ENMs at the estimated release level in 2020. Compared to static models, the dynamic material flow model allowed us to use PEC values based on a more complex parameterization, considering a dynamic input over time and time-dependent release of ENMs. The probabilistic SSD approach makes it possible to include all available data to estimate hazards of ENMs by considering the whole range of variability between studies and material types. The risk-assessment approach is therefore able to handle the uncertainty and variability associated with the collected data. The results of the present study provide a scientific foundation for risk-based regulatory decisions of the investigated ENMs. Environ Toxicol Chem 2018;37:1387-1395. © 2018 SETAC. © 2018 SETAC.

Study of nano-architecture of the wings of Paris Peacock butterfly

NASA Astrophysics Data System (ADS)

Ghate, Ekata; Bhoraskar, S. V.; Kulkarni, G. R.

Butterflies are one of the most colorful creatures in animal Kingdom. Wings of the male butterfly are brilliantly colored to attract females. Color of the wings plays an important role in camouflage. Study of structural colors in case of insects and butterflies are important for their biomimic and biophotonic applications. Structural color is the color which is produced by physical structures and their interaction with light. Paris Peacock or Papilio paris butterfly belongs to the family Papilionidae. The basis of structural color of this butterfly is investigated in the present study. The upper surface of the wings in this butterfly is covered with blue, green and brown colored scales. Nano-architecture of these scales was investigated with scanning electron microscope (SEM) and environmental scanning electron microscope (ESEM). Photomicrographs were analyzed using image analysis software. Goniometric color or iridescence in blue and green colored scales of this butterfly was observed and studied with the help of gonio spectrophotometer in the visible range. No iridescence was observed in brown colored scales of the butterfly. Hues of the blue and green color were measured with spectrophotometer and were correlated with nano-architecture of the wing. Results of electron microscopy and reflection spectroscopy are used to explain the iridescent nature of blue and green scales. Sinusoidal grating like structures of these scales were prominently seen in the blue scales. It is possible that the structure of these wings can act as a template for the fabrication of sinusoidal gratings using nano-imprint technology.

Pore-scale modeling of moving contact line problems in immiscible two-phase flow.

NASA Astrophysics Data System (ADS)

Kucala, A.; Noble, D.; Martinez, M. J.

2016-12-01

Two immiscible fluids in static equilibrium form a common interface along a solid surface, characterized as the static contact (wetting) angle and is a function of surface geometry, intermolecular forces, and interfacial surface energies manifested as interfacial tension. This static configuration may become perturbed due to external force imbalances (mass injection, pressure gradients, buoyancy, etc.) and the contact line location and interface curvature becomes dynamic. Accurate modeling of moving contact line (MCL) problems is imperative in predicting capillary pressure vs. saturation curves, permeability, and preferential flow paths for a variety of applications, including geological carbon storage (GCS) and enhanced oil recovery (EOR). Here, we present a model for the moving contact line using pore-scale computational fluid dynamics (CFD) which solves the full, time-dependent Navier-Stokes equations using the Galerkin finite-element method. The MCL is modeled as a surface traction force proportional to the surface tension, dependent on the static properties of the immiscible fluid/solid system. The moving two-phase interface is tracked using the level set method and discretized with the conformal decomposition finite element method (CDFEM), allowing for surface tension effects to be computed at the exact interface location. We present a variety of verification test cases for simple two- and three-dimensional geometries to validate the current model, including threshold pressure predictions in flows through pore-throats for a variety of wetting angles. Simulations involving more complex geometries are also presented to be used in future simulations for GCS and EOR problems. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000

ComplexContact: a web server for inter-protein contact prediction using deep learning.

PubMed

Zeng, Hong; Wang, Sheng; Zhou, Tianming; Zhao, Feifeng; Li, Xiufeng; Wu, Qing; Xu, Jinbo

2018-05-22

ComplexContact (http://raptorx2.uchicago.edu/ComplexContact/) is a web server for sequence-based interfacial residue-residue contact prediction of a putative protein complex. Interfacial residue-residue contacts are critical for understanding how proteins form complex and interact at residue level. When receiving a pair of protein sequences, ComplexContact first searches for their sequence homologs and builds two paired multiple sequence alignments (MSA), then it applies co-evolution analysis and a CASP-winning deep learning (DL) method to predict interfacial contacts from paired MSAs and visualizes the prediction as an image. The DL method was originally developed for intra-protein contact prediction and performed the best in CASP12. Our large-scale experimental test further shows that ComplexContact greatly outperforms pure co-evolution methods for inter-protein contact prediction, regardless of the species.

Nano-Electrochemistry and Nano-Electrografting with an Original Combined AFM-SECM

PubMed Central

Ghorbal, Achraf; Grisotto, Federico; Charlier, Julienne; Palacin, Serge; Goyer, Cédric; Demaille, Christophe; Ben Brahim, Ammar

2013-01-01

This study demonstrates the advantages of the combination between atomic force microscopy and scanning electrochemical microscopy. The combined technique can perform nano-electrochemical measurements onto agarose surface and nano-electrografting of non-conducting polymers onto conducting surfaces. This work was achieved by manufacturing an original Atomic Force Microscopy-Scanning ElectroChemical Microscopy (AFM-SECM) electrode. The capabilities of the AFM-SECM-electrode were tested with the nano-electrografting of vinylic monomers initiated by aryl diazonium salts. Nano-electrochemical and technical processes were thoroughly described, so as to allow experiments reproducing. A plausible explanation of chemical and electrochemical mechanisms, leading to the nano-grafting process, was reported. This combined technique represents the first step towards improved nano-processes for the nano-electrografting. PMID:28348337

Controlling the near-field excitation of nano-antennas with phase-change materials.

PubMed

Kao, Tsung Sheng; Chen, Yi Guo; Hong, Ming Hui

2013-01-01

By utilizing the strongly induced plasmon coupling between discrete nano-antennas and quantitatively controlling the crystalline proportions of an underlying Ge2Sb2Te5 (GST) phase-change thin layer, we show that nanoscale light localizations in the immediate proximity of plasmonic nano-antennas can be spatially positioned. Isolated energy hot-spots at a subwavelength scale can be created and adjusted across the landscape of the plasmonic system at a step resolution of λ/20. These findings introduce a new approach for nano-circuitry, bio-assay addressing and imaging applications.

Nano-optical conveyor belt with waveguide-coupled excitation.

PubMed

Wang, Guanghui; Ying, Zhoufeng; Ho, Ho-pui; Huang, Ying; Zou, Ningmu; Zhang, Xuping

2016-02-01

We propose a plasmonic nano-optical conveyor belt for peristaltic transport of nano-particles. Instead of illumination from the top, waveguide-coupled excitation is used for trapping particles with a higher degree of precision and flexibility. Graded nano-rods with individual dimensions coded to have resonance at specific wavelengths are incorporated along the waveguide in order to produce spatially addressable hot spots. Consequently, by switching the excitation wavelength sequentially, particles can be transported to adjacent optical traps along the waveguide. The feasibility of this design is analyzed using three-dimensional finite-difference time-domain and Maxwell stress tensor methods. Simulation results show that this system is capable of exciting addressable traps and moving particles in a peristaltic fashion with tens of nanometers resolution. It is the first, to the best of our knowledge, report about a nano-optical conveyor belt with waveguide-coupled excitation, which is very important for scalability and on-chip integration. The proposed approach offers a new design direction for integrated waveguide-based optical manipulation devices and its application in large scale lab-on-a-chip integration.

Programmable Nano-Bio Interfaces for Functional Biointegrated Devices.

PubMed

Cai, Pingqiang; Leow, Wan Ru; Wang, Xiaoyuan; Wu, Yun-Long; Chen, Xiaodong

2017-07-01

A large amount of evidence has demonstrated the revolutionary role of nanosystems in the screening and shielding of biological systems. The explosive development of interfacing bioentities with programmable nanomaterials has conveyed the intriguing concept of nano-bio interfaces. Here, recent advances in functional biointegrated devices through the precise programming of nano-bio interactions are outlined, especially with regard to the rational assembly of constituent nanomaterials on multiple dimension scales (e.g., nanoparticles, nanowires, layered nanomaterials, and 3D-architectured nanomaterials), in order to leverage their respective intrinsic merits for different functions. Emerging nanotechnological strategies at nano-bio interfaces are also highlighted, such as multimodal diagnosis or "theragnostics", synergistic and sequential therapeutics delivery, and stretchable and flexible nanoelectronic devices, and their implementation into a broad range of biointegrated devices (e.g., implantable, minimally invasive, and wearable devices). When utilized as functional modules of biointegrated devices, these programmable nano-bio interfaces will open up a new chapter for precision nanomedicine. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrospray neutralization process and apparatus for generation of nano-aerosol and nano-structured materials

DOEpatents

Bailey, Charles L.; Morozov, Victor; Vsevolodov, Nikolai N.

2010-08-17

The claimed invention describes methods and apparatuses for manufacturing nano-aerosols and nano-structured materials based on the neutralization of charged electrosprayed products with oppositely charged electrosprayed products. Electrosprayed products include molecular ions, nano-clusters and nano-fibers. Nano-aerosols can be generated when neutralization occurs in the gas phase. Neutralization of electrospan nano-fibers with molecular ions and charged nano-clusters may result in the formation of fibrous aerosols or free nano-mats. Nano-mats can also be produced on a suitable substrate, forming efficient nano-filters.

Mn-silicide nanostructures aligned on massively parallel silicon nano-ribbons

NASA Astrophysics Data System (ADS)

De Padova, Paola; Ottaviani, Carlo; Ronci, Fabio; Colonna, Stefano; Olivieri, Bruno; Quaresima, Claudio; Cricenti, Antonio; Dávila, Maria E.; Hennies, Franz; Pietzsch, Annette; Shariati, Nina; Le Lay, Guy

2013-01-01

The growth of Mn nanostructures on a 1D grating of silicon nano-ribbons is investigated at atomic scale by means of scanning tunneling microscopy, low energy electron diffraction and core level photoelectron spectroscopy. The grating of silicon nano-ribbons represents an atomic scale template that can be used in a surface-driven route to control the combination of Si with Mn in the development of novel materials for spintronics devices. The Mn atoms show a preferential adsorption site on silicon atoms, forming one-dimensional nanostructures. They are parallel oriented with respect to the surface Si array, which probably predetermines the diffusion pathways of the Mn atoms during the process of nanostructure formation.

Mn-silicide nanostructures aligned on massively parallel silicon nano-ribbons.

PubMed

De Padova, Paola; Ottaviani, Carlo; Ronci, Fabio; Colonna, Stefano; Olivieri, Bruno; Quaresima, Claudio; Cricenti, Antonio; Dávila, Maria E; Hennies, Franz; Pietzsch, Annette; Shariati, Nina; Le Lay, Guy

2013-01-09

The growth of Mn nanostructures on a 1D grating of silicon nano-ribbons is investigated at atomic scale by means of scanning tunneling microscopy, low energy electron diffraction and core level photoelectron spectroscopy. The grating of silicon nano-ribbons represents an atomic scale template that can be used in a surface-driven route to control the combination of Si with Mn in the development of novel materials for spintronics devices. The Mn atoms show a preferential adsorption site on silicon atoms, forming one-dimensional nanostructures. They are parallel oriented with respect to the surface Si array, which probably predetermines the diffusion pathways of the Mn atoms during the process of nanostructure formation.

Evaluation of the adhesion on the nano-scaled polymeric film systems.

PubMed

Park, Tae Sung; Park, Ik Keun; Yoshida, Sanichiro

2017-04-01

We applied scanning acoustic microscopy known as the V(z) curve technique to photoresist thin-film systems for the evaluation of the adhesive strength at the film-substrate interface. Through the measurement of the SAW (Surface Acoustic Wave) velocity, the V(z) curve analysis allows us to quantify the stiffness of the film-substrate interface. In addition, we conducted a nano-scratch test to quantify the ultimate strength of the adhesion through the evaluation of the critical load. To vary the adhesive conditions, we prepared thin-film specimens with three different types of pre-coating surface treatments, i.e., oxygen-plasma bombardment, HMDS (Hexametyldisilazane) treatment and untreated. The magnitudes of the quantified stiffness and ultimate strength are found consistent with each other for all the specimens tested, indicating that the pre-coating surface treatment can strengthen both the stiffness and ultimate strength of the adhesion. The results of this study demonstrate the usefulness of the V(Z) analysis as a nondestructive method to evaluate the adhesion strength of nano-structured thin-film systems. Copyright © 2017 Elsevier B.V. All rights reserved.

A NANO enhancement to Moore's law

NASA Astrophysics Data System (ADS)

Wu, Jerry; Shen, Yin-Lin; Reinhardt, Kitt; Szu, Harold

2012-06-01

In the past 46 years, Intel Moore observed an exponential doubling in the number of transistors in every 18 months through the size reduction of individual transistor components since 1965. In this paper, we are exploring the nanotechnology impact upon the Law. Since we cannot break down the atomic size barrier, the fact implies a fundamental size limit at the atomic or Nanotechnology scale. This means, no more simple 18 month doubling as in Moore's Law, but other forms of transistor doubling may happen at a different slope in new directions. We are particularly interested in the Nano enhancement area. (i) 3-D: If the progress in shrinking the in-plane dimensions (2D) is to slow down, vertical integration (3D) can help increasing the areal device transistor density and keep us on the modified Moore's Law curve including the 3rd dimension. As the devices continue to shrink further into the 20 to 30 nm range, the consideration of thermal properties and transport in such nanoscale devices becomes increasingly important. (ii) Carbon Computing: Instead of traditional Transistors, the other types of transistors material are rapidly developed in Laboratories Worldwide, e.g. IBM Spintronics bandgap material and Samsung Nano-storage material, HD display Nanotechnology, which are modifying the classical Moore's Law. We shall consider the overall limitation of phonon engineering, fundamental information unit 'Qubyte' in quantum computing, Nano/Micro Electrical Mechanical System (NEMS), Carbon NanoTubes (CNTs), single layer Graphemes, single strip Nano-Ribbons, etc., and their variable degree of fabrication maturities for the computing and information processing applications.

Nano-materials enabled thermoelectricity from window glasses.

PubMed

Inayat, Salman B; Rader, Kelly R; Hussain, Muhammad M

2012-01-01

With a projection of nearly doubling up the world population by 2050, we need wide variety of renewable and clean energy sources to meet the increased energy demand. Solar energy is considered as the leading promising alternate energy source with the pertinent challenge of off sunshine period and uneven worldwide distribution of usable sun light. Although thermoelectricity is considered as a reasonable renewable energy from wasted heat, its mass scale usage is yet to be developed. Here we show, large scale integration of nano-manufactured pellets of thermoelectric nano-materials, embedded into window glasses to generate thermoelectricity using the temperature difference between hot outside and cool inside. For the first time, this work offers an opportunity to potentially generate 304 watts of usable power from 9 m(2) window at a 20°C temperature gradient. If a natural temperature gradient exists, this can serve as a sustainable energy source for green building technology.

Impact of polymer electrolyte membrane fuel cell microporous layer nano-scale features on thermal conductance

NASA Astrophysics Data System (ADS)

Botelho, S. J.; Bazylak, A.

2015-04-01

In this study, the microporous layer (MPL) of the polymer electrolyte membrane (PEM) fuel cell was analysed at the nano-scale. Atomic force microscopy (AFM) was utilized to image the top layer of MPL particles, and a curve fitting algorithm was used to determine the particle size and filling radius distributions for SGL-10BB and SGL-10BC. The particles in SGL-10BC (approximately 60 nm in diameter) have been found to be larger than those in SGL-10BB (approximately 40 nm in diameter), highlighting structural variability between the two materials. The impact of the MPL particle interactions on the effective thermal conductivity of the bulk MPL was analysed using a discretization of the Fourier equation with the Gauss-Seidel iterative method. It was found that the particle spacing and filling radius dominates the effective thermal conductivity, a result which provides valuable insight for future MPL design.

Nano- and Micro-Scale Oxidative Patterning of Titanium Implant Surfaces for Improved Surface Wettability.

PubMed

Kim, In-hye; Son, Jun Sik; Choi, Seok Hwa; Kim, Kyo-han; Kwon, Tae-yub

2016-02-01

A simple and scalable surface modification treatment is demonstrated, in which nano- and microscale features are introduced into the surface of titanium (Ti) substrates by means of a novel and eco-friendly oxidative aqueous solution composed of hydrogen peroxide (H202) and sodium bicarbonate (NaHCO3). By immersing mirror-polished Ti discs in an aqueous mixture of 30 wt% H2O2/5 wt% NaHCO3 at 23 +/- 3 degrees C for 4 h, it was confirmed that this mixture is capable of generating microscale topographies on Ti surfaces. It also simultaneously formed nanochannels that were regularly arranged in a comb-like pattern on the Ti surface, thus forming a hierarchical surface structure. Further, these nano/micro-textured Ti surfaces showed great surface roughness and excellent wettability when compared with control Ti surfaces. This study demonstrates that a H2O2/NaHCO3 mixture can be effectively utilized to create reproducible nano/microscale topographies on Ti implant surfaces, thus providing an economical new oxidative solution that may be used effectively and safely as a Ti surface modification treatment.

Scattering effects and high-spatial-frequency nanostructures on ultrafast laser irradiated surfaces of zirconium metallic alloys with nano-scaled topographies.

PubMed

Li, Chen; Cheng, Guanghua; Sedao, Xxx; Zhang, Wei; Zhang, Hao; Faure, Nicolas; Jamon, Damien; Colombier, Jean-Philippe; Stoian, Razvan

2016-05-30

The origin of high-spatial-frequency laser-induced periodic surface structures (HSFL) driven by incident ultrafast laser fields, with their ability to achieve structure resolutions below λ/2, is often obscured by the overlap with regular ripples patterns at quasi-wavelength periodicities. We experimentally demonstrate here employing defined surface topographies that these structures are intrinsically related to surface roughness in the nano-scale domain. Using Zr-based bulk metallic glass (Zr-BMG) and its crystalline alloy (Zr-CA) counterpart formed by thermal annealing from its glassy precursor, we prepared surfaces showing either smooth appearances on thermoplastic BMG or high-density nano-protuberances from randomly distributed embedded nano-crystallites with average sizes below 200 nm on the recrystallized alloy. Upon ultrashort pulse irradiation employing linearly polarized 50 fs, 800 nm laser pulses, the surfaces show a range of nanoscale organized features. The change of topology was then followed under multiple pulse irradiation at fluences around and below the single pulse threshold. While the former material (Zr-BMG) shows a specific high quality arrangement of standard ripples around the laser wavelength, the latter (Zr-CA) demonstrates strong predisposition to form high spatial frequency rippled structures (HSFL). We discuss electromagnetic scenarios assisting their formation based on near-field interaction between particles and field-enhancement leading to structure linear growth. Finite-difference-time-domain simulations outline individual and collective effects of nanoparticles on electromagnetic energy modulation and the feedback processes in the formation of HSFL structures with correlation to regular ripples (LSFL).

Doping dependence of the contact resistivity of end-bonded metal contacts to thin heavily doped semiconductor nanowires

NASA Astrophysics Data System (ADS)

Shukkoor, Anvar A.; Karmalkar, Shreepad

2017-12-01

We study the resistivity, ρcN, of end-bonded contacts to semiconductor NanoWires (NWs) of radius R = 5-10 nm over doping Nd = 1018-1020 cm-3. The study is important for NW device design and characterization. It reports realistic calculations of ρcN and highlights and explains how ρcN differs significantly from the resistivity ρcB of bulk contacts. First, the space-charge width in NW contacts is increased by the surrounding field which depends on R, contact geometry, and ambient dielectric; this width also depends on surface charge and dielectric confinement which reduces dopant ionization. Second, thin NWs have a low effective lifetime, τN, due to surface recombination. Third, NW contacts have a lesser image force barrier lowering due to the higher space-charge width. Due to these factors, apart from tunneling (which decides ρcB), space-charge region generation-recombination current also affects ρcN. As Nd is raised from 1018 to 1020 cm-3, ρcB falls rapidly, but ρcN varies slowly and may even increase up to 3-5 × 1018 and then falls rapidly. Further, ρcN/ρcB can be ≪1 at Nd = 1 × 1018 cm-3, reaches a peak ≫1 around Nd = 1 × 1019 cm-3, and → 1 at Nd = 1 × 1020 cm-3, e.g., for 0.8 V contact barrier on 10 nm thick n-type silicon NWs with τN = 1 ps embedded in SiO2, at T = 300 K, even a 10 nm contact extension yields a peak of 75 at Nd = 8 × 1018 cm-3. We study changes in ρcN/ρcB versus Nd behavior with R, contact geometry, ambient dielectric, surface charge, τN, T, tunneling mass, and barrier height.

Microbial contamination of contact lenses after scaling and root planing using ultrasonic scalers with and without protective eyewear: A clinical and microbiological study

PubMed Central

Afzha, Rooh; Chatterjee, Anirban; Subbaiah, Shobha Krishna; Pradeep, Avani Rangaraju

2016-01-01

Background: Ultrasonic scaler is a preferential treatment modality among the clinicians. However, the aerosol/splatter generated is a concern for patients and practitioners. Therefore, the purpose of this study was to evaluate contamination of contact lenses of the dentist after scaling and root planing using ultrasonic scalers with and without protective eyewear. Materials and Methods: Thirty patients were randomly selected for scaling and root planing and divided into 2 groups of 15 each. Group A – dentist wearing contact lenses and protective eyewear. Group B - dentist wearing only contact lenses. After scaling and root planing using ultrasonic scalers, the lenses were subjected to culture and 16S rRNA (16S ribosomal RNA) gene sequencing. Results: In Group A – 15 out of thirty samples were contaminated, in Group B – all the thirty samples were contaminated. Most of the samples showed Gram-positive bacteria and 5 samples were contaminated with fungi. 16S rRNA gene sequencing of forty contaminated samples showed that 31 were contaminated with Streptococcus mutans and 9 with Staphylococcus aureus. Conclusion: Keeping in mind the limitation of the study for the absence of negative control, we would like to conclude that dental practitioners should better avoid contact lenses in a dental setup because of the risk of contamination of the contact lenses from the various dental procedures which can produce aerosol/splatter and if worn, it is recommended to wear protective eyewear. PMID:27563200

Nano Liquid Crystal Droplet Impact on Solid Surfaces

NASA Astrophysics Data System (ADS)

Zhang, Rui; de Pablo, Juan; dePablo Team

2015-03-01

Liquid droplet impaction on solid surfaces is an important problem with a wide range of applications in everyday life. Liquid crystals (LCs) are anisotropic liquids whose internal structure gives rise to rich optical and morphological phenomena. In this work we study the liquid crystal droplet impaction on solid surfaces by molecular dynamics simulations. We employ a widely used Gay-Berne model to describe the elongated liquid crystal molecules and their interactions. Our work shows that, in contrast to isotropic liquids, drop deformation is symmetric unless an instability kicks in, in which case a nano scale liquid crystal droplet exhibits distinct anisotropic spreading modes that do not occur in simple liquids. The drop prefers spreading along the low viscosity direction, but inertia can in some cases overcome that bias. The effects of the director field of the droplet, preferred anchoring direction and the anchoring strength of the wall are investigated. Large scale (0.1 micron) simulations are performed to connect our nano scale results to the experiments. Our studies indicate that LCs could provide an interesting alternative for development of next-generation printing inks.

Nanomanufacturing : nano-structured materials made layer-by-layer.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cox, James V.; Cheng, Shengfeng; Grest, Gary Stephen

Large-scale, high-throughput production of nano-structured materials (i.e. nanomanufacturing) is a strategic area in manufacturing, with markets projected to exceed $1T by 2015. Nanomanufacturing is still in its infancy; process/product developments are costly and only touch on potential opportunities enabled by growing nanoscience discoveries. The greatest promise for high-volume manufacturing lies in age-old coating and imprinting operations. For materials with tailored nm-scale structure, imprinting/embossing must be achieved at high speeds (roll-to-roll) and/or over large areas (batch operation) with feature sizes less than 100 nm. Dispersion coatings with nanoparticles can also tailor structure through self- or directed-assembly. Layering films structured with thesemore » processes have tremendous potential for efficient manufacturing of microelectronics, photovoltaics and other topical nano-structured devices. This project is designed to perform the requisite R and D to bring Sandia's technology base in computational mechanics to bear on this scale-up problem. Project focus is enforced by addressing a promising imprinting process currently being commercialized.« less

Tortuous pathways: Fundamental characterisation of the anisotropic permeability through clay-rich shales from macro- to nano-scale.

NASA Astrophysics Data System (ADS)

Mitchell, T. M.; Backeberg, N. R.; Iacoviello, F.; Rittner, M.; Jones, A. P.; Wheeler, J.; Day, R.; Vermeesch, P.; Shearing, P. R.; Striolo, A.

2017-12-01

The permeability of shales is important, because it controls where oil and gas resources can migrate to and where in the Earth hydrocarbons are ultimately stored. Shales have a well-known anisotropic directional permeability that is inherited from the depositional layering of sedimentary laminations, where the highest permeability is measured parallel to laminations and the lowest permeability is perpendicular to laminations. We combine state of the art laboratory permeability experiments with high-resolution X-ray computed tomography and for the first time can quantify the three-dimensional interconnected pathways through a rock that define the anisotropic behaviour of shales. Experiments record a physical anisotropy in permeability of one to two orders of magnitude. Two- and three-dimensional analyses of micro- and nano-scale X-ray computed tomography illuminate that the directional anisotropy is fundamentally controlled by the bulk rock mineral geometry, which determines the finite length (or tortuosity) of the interconnected pathways through the porous/permeable phases in shales. Understanding the mineral-scale control on permeability will allow for better estimations of the extent of recoverable reserves in shale gas plays globally.

Contingency planning for a deliberate release of smallpox in Great Britain--the role of geographical scale and contact structure.

PubMed

House, Thomas; Hall, Ian; Danon, Leon; Keeling, Matt J

2010-02-14

In the event of a release of a pathogen such as smallpox, which is human-to-human transmissible and has high associated mortality, a key question is how best to deploy containment and control strategies. Given the general uncertainty surrounding this issue, mathematical modelling has played an important role in informing the likely optimal response, in particular defining the conditions under which mass-vaccination would be appropriate. In this paper, we consider two key questions currently unanswered in the literature: firstly, what is the optimal spatial scale for intervention; and secondly, how sensitive are results to the modelling assumptions made about the pattern of human contacts? Here we develop a novel mathematical model for smallpox that incorporates both information on individual contact structure (which is important if the effects of contact tracing are to be captured accurately) and large-scale patterns of movement across a range of spatial scales in Great Britain. Analysis of this model confirms previous work suggesting that a locally targeted 'ring' vaccination strategy is optimal, and that this conclusion is actually quite robust for different socio-demographic and epidemiological assumptions. Our method allows for intuitive understanding of the reasons why national mass vaccination is typically predicted to be suboptimal. As such, we present a general framework for fast calculation of expected outcomes during the attempted control of diverse emerging infections; this is particularly important given that parameters would need to be interactively estimated and modelled in any release scenario.

Static and sliding contact of rough surfaces: Effect of asperity-scale properties and long-range elastic interactions

NASA Astrophysics Data System (ADS)

Hulikal, Srivatsan; Lapusta, Nadia; Bhattacharya, Kaushik

2018-07-01

Friction in static and sliding contact of rough surfaces is important in numerous physical phenomena. We seek to understand macroscopically observed static and sliding contact behavior as the collective response of a large number of microscopic asperities. To that end, we build on Hulikal et al. (2015) and develop an efficient numerical framework that can be used to investigate how the macroscopic response of multiple frictional contacts depends on long-range elastic interactions, different constitutive assumptions about the deforming contacts and their local shear resistance, and surface roughness. We approximate the contact between two rough surfaces as that between a regular array of discrete deformable elements attached to a elastic block and a rigid rough surface. The deformable elements are viscoelastic or elasto/viscoplastic with a range of relaxation times, and the elastic interaction between contacts is long-range. We find that the model reproduces the main macroscopic features of evolution of contact and friction for a range of constitutive models of the elements, suggesting that macroscopic frictional response is robust with respect to the microscopic behavior. Viscoelasticity/viscoplasticity contributes to the increase of friction with contact time and leads to a subtle history dependence. Interestingly, long-range elastic interactions only change the results quantitatively compared to the meanfield response. The developed numerical framework can be used to study how specific observed macroscopic behavior depends on the microscale assumptions. For example, we find that sustained increase in the static friction coefficient during long hold times suggests viscoelastic response of the underlying material with multiple relaxation time scales. We also find that the experimentally observed proportionality of the direct effect in velocity jump experiments to the logarithm of the velocity jump points to a complex material-dependent shear resistance at the

Measuring helium nano-bubble formation in tungsten with grazing-incidence small angle X-ray scattering

NASA Astrophysics Data System (ADS)

Thompson, Matt A. T.

The behaviour of helium in tungsten is an important concern for the fusion materials community. Under helium plasma exposure, small nano-scale bubbles form beneath the material surface as helium precipitates from the tungsten matrix. Under certain conditions this can lead to the subsequent formation of a surface "nano-fuzz", though the mechanisms of this process are not presently understood. For sub-surface nano-bubble formation transmission electron microscopy (TEM) has been the most widely used technique. While certainly a powerful technique, TEM suffers from a number of significant drawbacks: sample preparation is difficult and destructive, and there are sampling limitations as nano-structures must be located and characterised individually. This makes quantitative characterisation of nano-scale modification in tungsten challenging, which in turn makes it difficult to perform systematic studies on the effects of factors such as temperature and plasma composition on nano-scale modification. Here, Grazing Incidence Small Angle X-ray Scattering (GISAXS) is presented as a powerful addition to the field of fusion materials. With GISAXS, one can measure the X-ray scattering from nano-scale features throughout a relatively large volume, allowing information about full nano-bubble size distributions to be obtained from a simple, non-destructive measurement. Where it typically takes days or weeks to prepare a sample and study it under TEM, GISAXS measurements can be performed in a matter of minutes, and the data analysis performed autonomously by a computer in hours. This thesis describes the work establishing GISAXS as a viable technique for fusion materials. A GISAXS pattern fitting model was first developed, and then validated via comparison between GISAXS and TEM measurements of helium induced nano-bubble formation in tungsten exposed to a helium discharge in the large helical device. Under these conditions, nano-bubbles were found to follow an approximately

Synchronized femtosecond laser pulse switching system based nano-patterning technology

NASA Astrophysics Data System (ADS)

Sohn, Ik-Bu; Choi, Hun-Kook; Yoo, Dongyoon; Noh, Young-Chul; Sung, Jae-Hee; Lee, Seong-Ku; Ahsan, Md. Shamim; Lee, Ho

2017-07-01

This paper demonstrates the design and development of a synchronized femtosecond laser pulse switching system and its applications in nano-patterning of transparent materials. Due to synchronization, we are able to control the location of each irradiated laser pulse in any kind of substrate. The control over the scanning speed and scanning step of the laser beam enables us to pattern periodic micro/nano-metric holes, voids, and/or lines in various materials. Using the synchronized laser system, we pattern synchronized nano-holes on the surface of and inside various transparent materials including fused silica glass and polymethyl methacrylate to replicate any image or pattern on the surface of or inside (transparent) materials. We also investigate the application areas of the proposed synchronized femtosecond laser pulse switching system in a diverse field of science and technology, especially in optical memory, color marking, and synchronized micro/nano-scale patterning of materials.

A large-scale examination of the nature and efficacy of teachers' practices to engage parents: assessment, parental contact, and student-level impact.

PubMed

Seitsinger, Anne M; Felner, Robert D; Brand, Stephen; Burns, Amy

2008-08-01

As schools move forward with comprehensive school reform, parents' roles have shifted and been redefined. Parent-teacher communication is critical to student success, yet how schools and teachers contact parents is the subject of few studies. Evaluations of school-change efforts require reliable and useful measures of teachers' practices in communicating with parents. The structure of teacher-parent-contact practices was examined using data from multiple, longitudinal cohorts of schools and teachers from a large-scale project and found to be a reliable and stable measure of parent contact across building levels and localities. Teacher/school practices in contacting parents were found to be significantly related to parent reports of school contact performance and student academic adjustment and achievement. Implications for school improvement efforts are discussed.

Architecture and permeability of post-cytokinesis plasmodesmata lacking cytoplasmic sleeves.

PubMed

Nicolas, William J; Grison, Magali S; Trépout, Sylvain; Gaston, Amélia; Fouché, Mathieu; Cordelières, Fabrice P; Oparka, Karl; Tilsner, Jens; Brocard, Lysiane; Bayer, Emmanuelle M

2017-06-12

Plasmodesmata are remarkable cellular machines responsible for the controlled exchange of proteins, small RNAs and signalling molecules between cells. They are lined by the plasma membrane (PM), contain a strand of tubular endoplasmic reticulum (ER), and the space between these two membranes is thought to control plasmodesmata permeability. Here, we have reconstructed plasmodesmata three-dimensional (3D) ultrastructure with an unprecedented level of 3D information using electron tomography. We show that within plasmodesmata, ER-PM contact sites undergo substantial remodelling events during cell differentiation. Instead of being open pores, post-cytokinesis plasmodesmata present such intimate ER-PM contact along the entire length of the pores that no intermembrane gap is visible. Later on, during cell expansion, the plasmodesmata pore widens and the two membranes separate, leaving a cytosolic sleeve spanned by tethers whose presence correlates with the appearance of the intermembrane gap. Surprisingly, the post-cytokinesis plasmodesmata allow diffusion of macromolecules despite the apparent lack of an open cytoplasmic sleeve, forcing the reassessment of the mechanisms that control plant cell-cell communication.

Template-guided highly aligned, nano-scale wrinkle structure on a large-area

NASA Astrophysics Data System (ADS)

Lim, Jongcheon; Kim, Pilnam

This study presents a novel technique to induce aligned, nano-scale wrinkle on a polysiloxane-based UV curable resin. There have been studies on generating randomized sub-micron wrinkle using oxygen plasma treatment which causes equibiaxial compressive stress on the film surface. Few works have been reported on how to control the surface wrinkle orientation. Currently available approaches for regulating the wrinkle pattern typically require polydimethylsiloxane (PDMS)-based bilayer system under uniaxial stress condition which hampers various technological applications. Here, we demonstrate a method to generate aligned wrinkle with UV curable polymers. Highly regular array of nanoscale wrinkles were formed by elastic buckling of bilayered UV curable resin, resulting from a combination of confinement effect and anchor-guided propagation of structure. The wrinkle tends to align uniformly lateral to the template pattern as the resin filled in the pattern forms more convex meniscus. The wavelength of the wrinkle was controlled by UV exposure time yielding as small as 170nm. From our results, we suggest the confinement provided by the template pattern may have affected the direction of thin film's expansion yielding unidirectional compressive stress. This work was supported by Samsung Research Funding Center of Samsung Electronics under Project Number SRFC-IT1402-02.

Impacts of detrital nano- and micro-scale particles (dNP) on contaminant dynamics in a coal mine AMD treatment system.

PubMed

Lefticariu, Liliana; Sutton, Stephen R; Bender, Kelly S; Lefticariu, Mihai; Pentrak, Martin; Stucki, Joseph W

2017-01-01

Pollutants in acid mine drainage (AMD) are usually sequestered in neoformed nano- and micro-scale particles (nNP) through precipitation, co-precipitation, and sorption. Subsequent biogeochemical processes may control nNP stability and thus long-term contaminant immobilization. Mineralogical, chemical, and microbiological data collected from sediments accumulated over a six-year period in a coal-mine AMD treatment system were used to identify the pathways of contaminant dynamics. We present evidence that detrital nano- and micron-scale particles (dNP), composed mostly of clay minerals originating from the partial weathering of coal-mine waste, mediated biogeochemical processes that catalyzed AMD contaminant (1) immobilization by facilitating heterogeneous nucleation and growth of nNP in oxic zones, and (2) remobilization by promoting phase transformation and reductive dissolution of nNP in anoxic zones. We found that dNP were relatively stable under acidic conditions and estimated a dNP content of ~0.1g/L in the influent AMD. In the AMD sediments, the initial nNP precipitates were schwertmannite and poorly crystalline goethite, which transformed to well-crystallized goethite, the primary nNP repository. Subsequent reductive dissolution of nNP resulted in the remobilization of up to 98% of S and 95% of Fe accompanied by the formation of a compact dNP layer. Effective treatment of pollutants could be enhanced by better understanding the complex, dynamic role dNP play in mediating biogeochemical processes and contaminant dynamics at coal-mine impacted sites. Copyright © 2016 Elsevier B.V. All rights reserved.

Shielding properties of the ordinary concrete loaded with micro- and nano-particles against neutron and gamma radiations.

PubMed

Mesbahi, Asghar; Ghiasi, Hosein

2018-06-01

The shielding properties of ordinary concrete doped with some micro and nano scaled materials were studied in the current study. Narrow beam geometry was simulated using MCNPX Monte Carlo code and the mass attenuation coefficient of ordinary concrete doped with PbO 2 , Fe 2 O 3 , WO 3 and H 4 B (Boronium) in both nano and micro scales was calculated for photon and neutron beams. Mono-energetic beams of neutrons (100-3000 keV) and photons (142-1250 keV) were used for calculations. The concrete doped with nano-sized particles showed higher neutron removal cross section (7%) and photon attenuation coefficient (8%) relative to micro-particles. Application of nano-sized material in the composition of new concretes for dual protection against neutrons and photons are recommended. For further studies, the calculation of attenuation coefficients of these nano-concretes against higher energies of neutrons and photons and different particles are suggested. Copyright © 2018 Elsevier Ltd. All rights reserved.

A multi-scale micromechanics framework for shale using the nano-tools

NASA Astrophysics Data System (ADS)

Ortega, J.; Ulm, F.; Abousleiman, Y.

2009-12-01

The successful prediction of poroelastic properties of fine-grained rocks such as shale continues to be a formidable challenge for the geophysics community. The highly heterogeneous nature of shale in terms of its compositional and microstructural features translates into a complex anisotropic behavior observed at macroscopic length scales. The recent application of instrumented indentation for the mechanical characterization of shale has revealed the granular response and intrinsic anisotropy of its porous clay phase at nanometer length scales [1-2]. This discovered mechanical behavior at the grain scale has been incorporated into the development of a multi-scale, micromechanics model for shale poroelasticity [3]. The only inputs to the model are two volumetric parameters synthesizing the mineralogy and porosity information of a shale sample. The model is meticulously calibrated and validated, as displayed in Fig. 1, with independent data sets of anisotropic elasticity obtained from nanoindentation experiments and standard laboratory acoustic measurements for shale specimens with and without organic content. The treatment of the elastic anisotropy corresponding to the porous clay fabric, as sensed by nanoindentation, delineates the contribution of the intrinsic anisotropy in shale to its overall anisotropy observed at macroscales. Furthermore, the proposed poroelastic formulation provides access to intrinsic rock parameters such as Biot pore pressure coefficients that are of importance for problems of flow in porous media. In addition, the model becomes a useful tool in geophysics applications for the prediction of shale acoustic properties from material-specific information such as porosity, mineralogy, and density measurements. References: [1] Ulm, F.-J., Abousleiman, Y. (2006) ‘The nanogranular nature of shale.’ Acta Geot. 1(2), 77-88. [2] Bobko, C., Ulm, F.-J. (2008) ‘The nano-mechanical morphology of shale.’ Mech. Mat. 40(4-5), 318-337. [3] Ortega, J

The applications of small-angle X-ray scattering in studying nano-scaled polyoxometalate clusters in solutions

NASA Astrophysics Data System (ADS)

Li, Mu; Zhang, Mingxin; Wang, Weiyu; Cheng, Stephen Z. D.; Yin, Panchao

2018-05-01

Nano-scaled polyoxometalates (POMs) clusters with sizes ranging from 1 to 10 nm attract tremendous attention and have been extensively studied due to POMs' fascinating structural characteristics and prospects for wide-ranging applications. As a unique class of nanoparticles with well-defined structural topologies and monodispersed masses, the structures and properties of POMs in both bulk state and solutions have been explored with several well-developed protocols. Small-angle X-ray scattering (SAXS) technique, as a powerful tool for studying polymers and nanoparticles, has been recently extended to the investigating of solution behaviors of POMs. In this mini-review, the general principle and typical experimental procedures of SAXS are illustrated first. The applications of SAXS in characterizing POMs' morphology, counterion distribution around POMs, and short-range interactions among POMs in solutions are highlighted. [Figure not available: see fulltext.

Stromatolites in the approximately 3400 Ma Strelley Pool Formation, Western Australia: examining biogenicity from the macro- to the nano-scale.

PubMed

Wacey, David

2010-05-01

The 3426-3350 Ma Strelley Pool Formation (SPF) is a silicified, dominantly sedimentary unit within the Pilbara Supergroup, Western Australia. It is found widely across the East Pilbara Terrane, and it forms a prominent marker horizon and separates the largely volcanic 3520-3427 Ma Warrawoona and 3350-3315 Ma Kelly groups. It has become one of the key formations for study by astrobiologists, following reports of some of the world's oldest stromatolites. Abundant contextural and morphological evidence has been presented over the last decade in support of a biological role in SPF stromatolite formation. This evidence is reviewed here, and additional data are presented from recent fieldwork carried out across the approximately 25 km of SPF outcrops in the East Strelley greenstone belt of the East Pilbara Terrane. In addition to contextural and morphological evidence, a compelling claim for early life requires geochemical evidence for biological cycling. A potential avenue of approach to obtain such evidence for the SPF stromatolites (and other ancient examples) is discussed in the context of a pilot study in which nano-scale secondary ion mass spectrometry (NanoSIMS) was used.

Micro- and nano-X-ray computed-tomography: A step forward in the characterization of the pore network of a leached cement paste

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bossa, Nathan, E-mail: bossanathan@gmail.com; INERIS, Parc Technologique Alata, BP2, 60550 Verneuil-en-Halatte; iCEINT, CNRS, Duke Univ. International Consortium for the Environmental Implications of Nanotechnology, Aix-en-Provence

2015-01-15

Pore structure of leached cement pastes (w/c = 0.5) was studied for the first time from micro-scale down to the nano-scale by combining micro- and nano-X-ray computed tomography (micro- and nano-CT). This allowed assessing the 3D heterogeneity of the pore network along the cement profile (from the core to the altered layer) of almost the entire range of cement pore size, i.e. from capillary to gel pores. We successfully quantified an increase of porosity in the altered layer at both resolutions. Porosity is increasing from 1.8 to 6.1% and from 18 to 58% at the micro-(voxel = 1.81 μm) andmore » nano-scale (voxel = 63.5 nm) respectively. The combination of both CT allowed to circumvent weaknesses inherent of both investigation scales. In addition the connectivity and the channel size of the pore network were also evaluated to obtain a complete 3D pore network characterization at both scales.« less

Performance assessment of an irreversible nano Brayton cycle operating with Maxwell-Boltzmann gas

NASA Astrophysics Data System (ADS)

Açıkkalp, Emin; Caner, Necmettin

2015-05-01

In the last decades, nano-technology has been developed very fast. According to this, nano-cycle thermodynamics should improve with a similar rate. In this paper, a nano-scale irreversible Brayton cycle working with helium is evaluated for different thermodynamic criteria. These are maximum work output, ecological function, ecological coefficient of performance, exergetic performance criteria and energy efficiency. Thermodynamic analysis was performed for these criteria and results were submitted numerically. In addition, these criteria are compared with each other and the most convenient methods for the optimum conditions are suggested.

Pulsed 86Sr-labeling and NanoSIMS imaging to study coral biomineralization at ultra-structural length scales

NASA Astrophysics Data System (ADS)

Brahmi, C.; Domart-Coulon, I.; Rougée, L.; Pyle, D. G.; Stolarski, J.; Mahoney, J. J.; Richmond, R. H.; Ostrander, G. K.; Meibom, A.

2012-09-01

A method to label marine biocarbonates is developed based on a concentration enrichment of a minor stable isotope of a trace element that is a natural component of seawater, resulting in the formation of biocarbonate with corresponding isotopic enrichments. This biocarbonate is subsequently imaged with a NanoSIMS ion microprobe to visualize the locations of the isotopic marker on sub-micrometric length scales, permitting resolution of all ultra-structural details. In this study, a scleractinian coral, Pocillopora damicornis, was labeled 3 times with 86Sr-enhanced seawater for a period of 48 h with 5 days under normal seawater conditions separating each labeling event. Two non-specific cellular stress biomarkers, glutathione-S-transferase activity and porphyrin concentration plus carbonic anhydrase, an enzymatic marker involved in the physiology of carbonate biomineralization, as well as unchanged levels of zooxanthellae photosynthesis efficiency indicate that coral physiological processes are not affected by the 86Sr-enhancement. NanoSIMS images of the 86Sr/44Ca ratio in skeleton formed during the experiment allow for a determination of the average extension rate of the two major ultra-structural components of the coral skeleton: Rapid Accretion Deposits are found to form on average about 4.5 times faster than Thickening Deposits. The method opens up new horizons in the study of biocarbonate formation because it holds the potential to observe growth of calcareous structures such as skeletons, shells, tests, spines formed by a wide range of organisms under essentially unperturbed physiological conditions.

Electroless Deposition and Nanolithography Can Control the Formation of Materials at the Nano-Scale for Plasmonic Applications

PubMed Central

Coluccio, Maria Laura; Gentile, Francesco; Francardi, Marco; Perozziello, Gerardo; Malara, Natalia; Candeloro, Patrizio; Di Fabrizio, Enzo

2014-01-01

The new revolution in materials science is being driven by our ability to manipulate matter at the molecular level to create structures with novel functions and properties. The aim of this paper is to explore new strategies to obtain plasmonic metal nanostructures through the combination of a top down method, that is electron beam lithography, and a bottom up technique, that is the chemical electroless deposition. This technique allows a tight control over the shape and size of bi- and three-dimensional metal patterns at the nano scale. The resulting nanostructures can be used as constituents of Surface Enhanced Raman Spectroscopy (SERS) substrates, where the electromagnetic field is strongly amplified. Our results indicate that, in electroless growth, high quality metal nanostructures with sizes below 50 nm may be easily obtained. These findings were explained within the framework of a diffusion limited aggregation (DLA) model, that is a simulation model that makes it possible to decipher, at an atomic level, the rules governing the evolution of the growth front; moreover, we give a description of the physical mechanisms of growth at a basic level. In the discussion, we show how these findings can be utilized to fabricate dimers of silver nanospheres where the size and shape of those spheres is controlled with extreme precision and can be used for very large area SERS substrates and nano-optics, for single molecule detection. PMID:24681672

Diffraction efficiency growth of nano-scale holographic recording produced in a corona discharge

NASA Astrophysics Data System (ADS)

Bodurov, I.; Yovcheva, T.; Vlaeva, I.; Viraneva, A.; Todorov, R.; Spassov, G.; Sainov, S.

2012-12-01

The nano-scale holographic gratings ware recorded in 29 nm and 56 nm thick As2S3 films. The chalcogenide layers were deposited on a transparent chromium electrode with thickness 10 nm, produced on a glass substrate. Both chromium and chalcogenide films were deposited in one vacuum cycle by e-beam and thermal evaporation, respectively. The diode 532 nm diode laser was used as a light source in the present holographic experiments. The total internal reflection arrangement (Stetson-Nassenstein) was used in holographic recordings. The reference beam was totally reflected from the air-As2S3 boundary surface by an input glass prism. The object beam was normally incident on the recording medium. The corona charging was performed by a needle fixed at the distance of 1 cm from the holographic recording medium by applying a - 5 kV voltage. The diffraction efficiency increased from 9 to 30 times when the corona discharge was applied during the holographic recording, in comparison to the uncharged recording. The possible reason of the observed effect is discussed on the basis of the Franz-Keldysh effect and Moss rule.

Nano-Scale Hydroxyapatite: Synthesis, Two-Dimensional Transport Experiments, and Application for Uranium Remediation

DOE PAGES

Kanel, S. R.; Clement, T. P.; Barnett, M. O.; ...

2011-01-01

Synthetic nano-scale hydroxyapatite (NHA) was prepared and characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM) methods. The XRD data confirmed that the crystalline structure and chemical composition of NHA correspond to Ca 5 OH(PO 4 ) 3 . The SEM data confirmed the size of NHA to be less than 50 nm. A two-dimensional physical model packed with saturated porous media was used to study the transport characteristics of NHA under constant flow conditions. The data show that the transport patterns of NHA were almost identical to tracer transport patterns. This result indicates that the NHA material can movemore » with water like a tracer, and its movement was neither retarded nor influenced by any physicochemical interactions and/or density effects. We have also tested the reactivity of NHA with 1 mg/L hexavalent uranium (U(VI)) and found that complete removal of U(VI) is possible using 0.5 g/L NHA at pH 5 to 6. Our results demonstrate that NHA has the potential to be injected as a dilute slurry for in situ treatment of U(VI)-contaminated groundwater systems.« less

Mechanical properties of cement concrete composites containing nano-metakaolin

NASA Astrophysics Data System (ADS)

Supit, Steve Wilben Macquarie; Rumbayan, Rilya; Ticoalu, Adriana

2017-11-01

The use of nano materials in building construction has been recognized because of its high specific surface area, very small particle sizes and more amorphous nature of particles. These characteristics lead to increase the mechanical properties and durability of cement concrete composites. Metakaolin is one of the supplementary cementitious materials that has been used to replace cement in concrete. Therefore, it is interesting to investigate the effectiveness of metakaolin (in nano scale) in improving the mechanical properties including compressive strength, tensile strength and flexural strength of cement concretes. In this experiment, metakaolin was pulverized by using High Energy Milling before adding to the concrete mixes. The pozzolan Portland cement was replaced with 5% and 10% nano-metakaolin (by wt.). The result shows that the optimum amount of nano-metakaolin in cement concrete mixes is 10% (by wt.). The improvement in compressive strength is approximately 123% at 3 days, 85% at 7 days and 53% at 28 days, respectively. The tensile and flexural strength results also showed the influence of adding 10% nano-metakaolin (NK-10) in improving the properties of cement concrete (NK-0). Furthermore, the Backscattered Electron images and X-Ray Diffraction analysis were evaluated to support the above findings. The results analysis confirm the pores modification due to nano-metakaolin addition, the consumption of calcium hydroxide (CH) and the formation of Calcium Silicate Hydrate (CSH) gel as one of the beneficial effects of amorphous nano-metakaolin in improving the mechanical properties and densification of microstructure of mortar and concrete.

Mobility, Deposition and Remobilization of pre-Synthesis Stabilized Nano-scale Zero Valent Iron in Long Column Experiments

NASA Astrophysics Data System (ADS)

de Boer, C. V.; O'Carroll, D. M.; Sleep, B.

2014-12-01

Reactive zero-valent iron is currently being used for remediation of contaminated groundwater. Permeable reactive barriers are the current state-of-the-practice method for using zero-valent iron. Instead of an excavated trench filled with granular zero-valent iron, a relatively new and promising method is the injection of a nano-scale zero-valent iron colloid suspension (nZVI) into the subsurface using injection wells. One goal of nZVI injection can be to deposit zero valent iron in the aquifer and form a reactive permeable zone which is no longer bound to limited depths and plume treatment, but can also be used directly at the source. It is very important to have a good understanding of the transport behavior of nZVI during injection as well as the fate of nZVI after injection due to changes in the flow regime or water chemistry changes. So far transport was mainly tested using commercially available nZVI, however these studies suggest that further work is required as commercial nZVI was prone to aggregation, resulting in low physical stability of the suspension and very short travel distances in the subsurface. In the presented work, nZVI is stabilized during synthesis to significantly increase the physical suspension stability. To improve our understanding of nZVI transport, the feasibility for injection into various porous media materials and controlled deposition, a suite of column experiments are conducted. The column experiments are performed using a long 1.5m column and a novel nZVI measuring technique. The measuring technique was developed to non-destructively determine the concentration of nano-scale iron during the injection. It records the magnetic susceptibility, which makes it possible to get transient nZVI retention profiles along the column. These transient nZVI retention profiles of long columns provide unique insights in the transport behavior of nZVI which cannot be obtained using short columns or effluent breakthrough curves.

SiGe nano-heteroepitaxy on Si and SiGe nano-pillars.

PubMed

Mastari, M; Charles, M; Bogumilowicz, Y; Thai, Q M; Pimenta-Barros, P; Argoud, M; Papon, A M; Gergaud, P; Landru, D; Kim, Y; Hartmann, J M

2018-07-06

In this paper, SiGe nano-heteroepitaxy on Si and SiGe nano-pillars was investigated in a 300 mm industrial reduced pressure-chemical vapour deposition tool. An integration scheme based on diblock copolymer patterning was used to fabricate nanometre-sized templates for the epitaxy of Si and SiGe nano-pillars. Results showed highly selective and uniform processes for the epitaxial growth of Si and SiGe nano-pillars. 200 nm thick SiGe layers were grown on Si and SiGe nano-pillars and characterised by atomic force microscopy, x-ray diffraction and transmission electron microscopy. Smooth SiGe surfaces and full strain relaxation were obtained in the 650 °C-700 °C range for 2D SiGe layers grown either on Si or SiGe nano-pillars.

Characterization and Curing Kinetics of Epoxy/Silica Nano-Hybrids

PubMed Central

Yang, Cheng-Fu; Wang, Li-Fen; Wu, Song-Mao; Su, Chean-Cheng

2015-01-01

The sol-gel technique was used to prepare epoxy/silica nano-hybrids. The thermal characteristics, curing kinetics and structure of epoxy/silica nano-hybrids were studied using differential scanning calorimetry (DSC), 29Si nuclear magnetic resonance (NMR) and transmission electron microscopy (TEM). To improve the compatibility between the organic and inorganic phases, a coupling agent was used to modify the diglycidyl ether of bisphenol A (DGEBA) epoxy. The sol-gel technique enables the silica to be successfully incorporated into the network of the hybrids, increasing the thermal stability and improving the mechanical properties of the prepared epoxy/silica nano-hybrids. An autocatalytic mechanism of the epoxy/SiO2 nanocomposites was observed. The low reaction rate of epoxy in the nanocomposites is caused by the steric hindrance in the network of hybrids that arises from the consuming of epoxide group in the network of hybrids by the silica. In the nanocomposites, the nano-scale silica particles had an average size of approximately 35 nm, and the particles were well dispersed in the epoxy matrix, according to the TEM images. PMID:28793616

Effect of nano/micro-Ag compound particles on the bio-corrosion, antibacterial properties and cell biocompatibility of Ti-Ag alloys.

PubMed

Chen, Mian; Yang, Lei; Zhang, Lan; Han, Yong; Lu, Zheng; Qin, Gaowu; Zhang, Erlin

2017-06-01

In this research, Ti-Ag alloys were prepared by powder metallurgy, casting and heat treatment method in order to investigate the effect of Ag compound particles on the bio-corrosion, the antibacterial property and the cell biocompatibility. Ti-Ag alloys with different sizes of Ag or Ag-compounds particles were successfully prepared: small amount of submicro-scale (100nm) Ti 2 Ag precipitates with solid solution state of Ag, large amount of nano-scale (20-30nm) Ti 2 Ag precipitates with small amount of solid solution state of Ag and micro-scale lamellar Ti 2 Ag phases, and complete solid solution state of Ag. The mechanical tests indicated that both nano/micro-scale Ti 2 Ag phases had a strong dispersion strengthening ability and Ag had a high solid solution strengthening ability. Electrochemical results shown the Ag content and the size of Ag particles had a limited influence on the bio-corrosion resistance although nano-scale Ti 2 Ag precipitates slightly improved corrosion resistance. It was demonstrated that the nano Ag compounds precipitates have a significant influence on the antibacterial properties of Ti-Ag alloys but no effect on the cell biocompatibility. It was thought that both Ag ions release and Ti 2 Ag precipitates contributed to the antibacterial ability, in which nano-scale and homogeneously distributed Ti 2 Ag phases would play a key role in antibacterial process. Copyright © 2017 Elsevier B.V. All rights reserved.

Micro/Nano-scale Strain Distribution Measurement from Sampling Moiré Fringes.

PubMed

Wang, Qinghua; Ri, Shien; Tsuda, Hiroshi

2017-05-23

This work describes the measurement procedure and principles of a sampling moiré technique for full-field micro/nano-scale deformation measurements. The developed technique can be performed in two ways: using the reconstructed multiplication moiré method or the spatial phase-shifting sampling moiré method. When the specimen grid pitch is around 2 pixels, 2-pixel sampling moiré fringes are generated to reconstruct a multiplication moiré pattern for a deformation measurement. Both the displacement and strain sensitivities are twice as high as in the traditional scanning moiré method in the same wide field of view. When the specimen grid pitch is around or greater than 3 pixels, multi-pixel sampling moiré fringes are generated, and a spatial phase-shifting technique is combined for a full-field deformation measurement. The strain measurement accuracy is significantly improved, and automatic batch measurement is easily achievable. Both methods can measure the two-dimensional (2D) strain distributions from a single-shot grid image without rotating the specimen or scanning lines, as in traditional moiré techniques. As examples, the 2D displacement and strain distributions, including the shear strains of two carbon fiber-reinforced plastic specimens, were measured in three-point bending tests. The proposed technique is expected to play an important role in the non-destructive quantitative evaluations of mechanical properties, crack occurrences, and residual stresses of a variety of materials.

Nano-scale characterization of the dynamics of the chloroplast Toc translocon.

PubMed

Reddick, L Evan; Chotewutmontri, Prakitchai; Crenshaw, Will; Dave, Ashita; Vaughn, Michael; Bruce, Barry D

2008-01-01

Translocons are macromolecular nano-scale machines that facilitate the selective translocation of proteins across membranes. Although common in function, different translocons have evolved diverse molecular mechanisms for protein translocation. Subcellular organelles of endosymbiotic origin such as the chloroplast and mitochondria had to evolve/acquire translocons capable of importing proteins whose genes were transferred to the host genome. These gene products are expressed on cytosolic ribosomes as precursor proteins and targeted back to the organelle by an N-terminal extension called the transit peptide or presequence. In chloroplasts the transit peptide is specifically recognized by the Translocon of the Outer Chloroplast membrane (Toc) which is composed of receptor GTPases that potentially function as gate-like switches, where GTP binding and hydrolysis somehow facilitate preprotein binding and translocation. Compared to other translocons, the dynamics of the Toc translocon are probably more complex and certainly less understood. We have developed biochemical/biophysical, imaging, and computational techniques to probe the dynamics of the Toc translocon at the nanoscale. In this chapter we provide detailed protocols for kinetic and binding analysis of precursor interactions in organeller, measurement of the activity and nucleotide binding of the Toc GTPases, native electrophoretic analysis of the assembly/organization of the Toc complex, visualization of the distribution and mobility of Toc apparatus on the surface of chloroplasts, and conclude with the identification and molecular modeling Toc75 POTRA domains. With these new methodologies we discuss future directions of the field.

Macro-mechanics controls quantum mechanics: mechanically controllable quantum conductance switching of an electrochemically fabricated atomic-scale point contact.

PubMed

Staiger, Torben; Wertz, Florian; Xie, Fangqing; Heinze, Marcel; Schmieder, Philipp; Lutzweiler, Christian; Schimmel, Thomas

2018-01-12

Here, we present a silver atomic-scale device fabricated and operated by a combined technique of electrochemical control (EC) and mechanically controllable break junction (MCBJ). With this EC-MCBJ technique, we can perform mechanically controllable bistable quantum conductance switching of a silver quantum point contact (QPC) in an electrochemical environment at room temperature. Furthermore, the silver QPC of the device can be controlled both mechanically and electrochemically, and the operating mode can be changed from 'electrochemical' to 'mechanical', which expands the operating mode for controlling QPCs. These experimental results offer the perspective that a silver QPC may be used as a contact for a nanoelectromechanical relay.

Macro-mechanics controls quantum mechanics: mechanically controllable quantum conductance switching of an electrochemically fabricated atomic-scale point contact

NASA Astrophysics Data System (ADS)

Staiger, Torben; Wertz, Florian; Xie, Fangqing; Heinze, Marcel; Schmieder, Philipp; Lutzweiler, Christian; Schimmel, Thomas

2018-01-01

Here, we present a silver atomic-scale device fabricated and operated by a combined technique of electrochemical control (EC) and mechanically controllable break junction (MCBJ). With this EC-MCBJ technique, we can perform mechanically controllable bistable quantum conductance switching of a silver quantum point contact (QPC) in an electrochemical environment at room temperature. Furthermore, the silver QPC of the device can be controlled both mechanically and electrochemically, and the operating mode can be changed from ‘electrochemical’ to ‘mechanical’, which expands the operating mode for controlling QPCs. These experimental results offer the perspective that a silver QPC may be used as a contact for a nanoelectromechanical relay.

Nano-hydroxyapatite could Compensate the Adverse Effect of soft carbonated Drinks on Enamel.

PubMed

Rezvani, Mohammad B; Rouhollahi, Mohammad R; Andalib, Fahimeh; Hamze, Faeze

2016-08-01

Since one of the most important disadvantages of soft drinks includes their adverse effect on mineral content of enamel because of their low pH, this study examined the microhardness of enamel before and after exposure to a soft drink containing different concentrations of nano-hydroxyapatite (nano-HA) as an additive. Sixty caries free human premolars were mounted in epoxy resin. After polishing, the baseline micro-hardness was recorded three times for each specimen using a Vickers indenter at 50 gm load. Subsequently, the samples were divided into six groups, which were treated for 5 minutes at 9°C by a cola-based drink contacting 0, 0.5, 1, 5, and 10 wt.% of nano-HA while the control group was immersed in artificial saliva. Ultimately, the final microhardness was assessed three times again for each specimen. Paired t-test showed that in groups containing 0 and 0.5 wt.% of nano-HA, the microhardness was significantly reduced after treatment protocol (p = 0.00 and 0.01 respectively). Whereas in the other groups the microhardness was not significantly changed after treatment (p > 0.05). Pure cola-based drink has a pronounced adverse effect on enamel microhardness, while admixing it with nano-HA could act as a protective factor. Although soft beverages are hazardous to tooth structure, some additives could compensate their adverse effect.

Self-Assembled Nano-energetic Gas Generators based on Bi2O3

NASA Astrophysics Data System (ADS)

Hobosyan, Mkhitar; Trevino, Tyler; Martirosyan, Karen

2012-10-01

Nanoenergetic Gas-Generators are formulations that rapidly release a large amount of gaseous products and generate a fast moving thermal wave. They are mainly based on thermite systems, which are pyrotechnic mixtures of metal powders (fuel- Al, Mg, etc.) and metal oxides (oxidizer, Bi2O3, Fe2O3, WO3, MoO3 etc.) that can generate an exothermic oxidation-reduction reaction referred to as a thermite reaction. A thermite reaction releases a large amount of energy and can generate rapidly extremely high temperatures. The intimate contact between the fuel and oxidizer can be enhanced by use of nano instead of micro particles. The contact area between oxidizer and metal particles depends from method of mixture preparation. In this work we utilize the self-assembly processes, which use the electrostatic forces to produce ordered and self-organized binary systems. In this process the intimate contact significantly enhances and gives the ability to build an energetic material in molecular level, which is crucial for thepressure discharge efficiency of nano-thermites. The DTA-TGA, Zeta-size analysis and FTIR technique were performed to characterize the Bi2O3 particles. The self-assembly of Aluminum and Bi2O3 was conducted in sonic bath with appropriate solvents and linkers. The resultant thermite pressure discharge values were tested in modified Parr reactor. In general, the self-assembled thermites give much higher-pressure discharge values than the thermites prepared with conventional roll-mixing technique.

Variation and Defect Tolerance for Nano Crossbars

NASA Astrophysics Data System (ADS)

Tunc, Cihan

With the extreme shrinking in CMOS technology, quantum effects and manufacturing issues are getting more crucial. Hence, additional shrinking in CMOS feature size seems becoming more challenging, difficult, and costly. On the other hand, emerging nanotechnology has attracted many researchers since additional scaling down has been demonstrated by manufacturing nanowires, Carbon nanotubes as well as molecular switches using bottom-up manufacturing techniques. In addition to the progress in manufacturing, developments in architecture show that emerging nanoelectronic devices will be promising for the future system designs. Using nano crossbars, which are composed of two sets of perpendicular nanowires with programmable intersections, it is possible to implement logic functions. In addition, nano crossbars present some important features as regularity, reprogrammability, and interchangeability. Combining these features, researchers have presented different effective architectures. Although bottom-up nanofabrication can greatly reduce manufacturing costs, due to low controllability in the manufacturing process, some critical issues occur. Bottom- up nanofabrication process results in high variation compared to conventional top- down lithography used in CMOS technology. In addition, an increased failure rate is expected. Variation and defect tolerance methods used for conventional CMOS technology seem inadequate for adapting to emerging nano technology because the variation and the defect rate for emerging nano technology is much more than current CMOS technology. Therefore, variations and defect tolerance methods for emerging nano technology are necessary for a successful transition. In this work, in order to tolerate variations for crossbars, we introduce a framework that is established based on reprogrammability and interchangeability features of nano crossbars. This framework is shown to be applicable for both FET-based and diode-based nano crossbars. We present a

Preparation of Nano-TiO₂-Coated SiO₂ Microsphere Composite Material and Evaluation of Its Self-Cleaning Property.

PubMed

Sun, Sijia; Deng, Tongrong; Ding, Hao; Chen, Ying; Chen, Wanting

2017-11-03

In order to improve the dispersion of nano-TiO₂ particles and enhance its self-cleaning properties, including photocatalytic degradation of pollutants and surface hydrophilicity, we prepared nano-TiO₂-coated SiO₂ microsphere composite self-cleaning materials (SiO₂-TiO₂) by co-grinding SiO₂ microspheres and TiO₂ soliquid and calcining the ground product. The structure, morphology, and self-cleaning properties of the SiO₂-TiO₂ were characterized. The characterization results showed that the degradation efficiency of methyl orange by SiO₂-TiO₂ was 97%, which was significantly higher than that obtained by pure nano-TiO₂. The minimum water contact angle of SiO₂-TiO₂ was 8°, indicating strong hydrophilicity and the good self-cleaning effect. The as-prepared SiO₂-TiO₂ was characterized by the nano-TiO₂ particles uniformly coated on the SiO₂ microspheres and distributed in the gap among the microspheres. The nano-TiO₂ particles were in an anatase phase with the particle size of 15-20 nm. The nano-TiO₂ particles were combined with SiO₂ microspheres via the dehydroxylation of hydroxyl groups on their surfaces.

The effect of thermal annealing on pentacene thin film transistor with micro contact printing.

PubMed

Shin, Hong-Sik; Yun, Ho-Jin; Baek, Kyu-Ha; Ham, Yong-Hyun; Park, Kun-Sik; Kim, Dong-Pyo; Lee, Ga-Won; Lee, Hi-Deok; Lee, Kijun; Do, Lee-Mi

2012-07-01

We used micro contact printing (micro-CP) to fabricate inverted coplanar pentacene thin film transistors (TFTs) with 1-microm channels. The patterning of micro-scale source/drain electrodes without etch process was successfully achieved using Polydimethylsiloxane (PDMS) elastomer stamp. We used the Ag nano particle ink as an electrode material, and the sheet resistance and surface roughness of the Ag electrodes were effectively reduced with the 2-step thermal annealing on a hotplate, which improved the mobility, the on-off ratio, and the subthreshold slope (SS) of the pentacene TFTs. In addition, the device annealing on a hotplate in a N2 atmosphere for 30 sec can enhance the off-current and the mobility properties of OTFTs without damaging the pentacene thin films and increase the adhesion between pentacene and dielectric layer (SiO2), which was investigated with the pentacene films phase change of the XRD spectrum after device annealing.

Molecular origin of contact line stick-slip motion during droplet evaporation

PubMed Central

Wang, FengChao; Wu, HengAn

2015-01-01

Understanding and controlling the motion of the contact line is of critical importance for surface science studies as well as many industrial engineering applications. In this work, we elucidate the molecular origin of contact line stick-slip motion during the evaporation of liquid droplets on flexible nano-pillared surfaces using molecular dynamics simulations. We demonstrate that the evaporation-induced stick-slip motion of the contact line is a consequence of competition between pinning and depinning forces. Furthermore, the tangential force exerted by the pillared substrate on the contact line was observed to have a sawtooth-like oscillation. Our analysis also establishes that variations in the pinning force are accomplished through the self-adaptation of solid-liquid intermolecular distances, especially for liquid molecules sitting directly on top of the solid pillar. Consistent with our theoretical analysis, molecular dynamics simulations also show that the maximum pinning force is quantitatively related to both solid-liquid adhesion strength and liquid-vapor surface tension. These observations provide a fundamental understanding of contact line stick-slip motion on pillared substrates and also give insight into the microscopic interpretations of contact angle hysteresis, wetting transitions and dynamic spreading. PMID:26628084

Plasmonic graded nano-disks as nano-optical conveyor belt.

PubMed

Kang, Zhiwen; Lu, Haifei; Chen, Jiajie; Chen, Kun; Xu, Fang; Ho, Ho-Pui

2014-08-11

We propose a plasmonic system consisting of nano-disks (NDs) with graded diameters for the realization of nano-optical conveyor belt. The system contains a couple of NDs with individual elements coded with different resonant wavelengths. By sequentially switching the wavelength and polarization of the excitation source, optically trapped target nano-particle can be transferred from one ND to another. The feasibility of such function is verified based on the three-dimensional finite-difference time-domain technique and the Maxwell stress tensor method. Our design may provide an alternative way to construct nano-optical conveyor belt with which target molecules can be delivered between trapping sites, thus enabling many on-chip optofluidic applications.

Towards an optimal contact metal for CNTFETs.

PubMed

Fediai, Artem; Ryndyk, Dmitry A; Seifert, Gotthard; Mothes, Sven; Claus, Martin; Schröter, Michael; Cuniberti, Gianaurelio

2016-05-21

Downscaling of the contact length Lc of a side-contacted carbon nanotube field-effect transistor (CNTFET) is challenging because of the rapidly increasing contact resistance as Lc falls below 20-50 nm. If in agreement with existing experimental results, theoretical work might answer the question, which metals yield the lowest CNT-metal contact resistance and what physical mechanisms govern the geometry dependence of the contact resistance. However, at the scale of 10 nm, parameter-free models of electron transport become computationally prohibitively expensive. In our work we used a dedicated combination of the Green function formalism and density functional theory to perform an overall ab initio simulation of extended CNT-metal contacts of an arbitrary length (including infinite), a previously not achievable level of simulations. We provide a systematic and comprehensive discussion of metal-CNT contact properties as a function of the metal type and the contact length. We have found and been able to explain very uncommon relations between chemical, physical and electrical properties observed in CNT-metal contacts. The calculated electrical characteristics are in reasonable quantitative agreement and exhibit similar trends as the latest experimental data in terms of: (i) contact resistance for Lc = ∞, (ii) scaling of contact resistance Rc(Lc); (iii) metal-defined polarity of a CNTFET. Our results can guide technology development and contact material selection for downscaling the length of side-contacts below 10 nm.

Electronic and Thermal Effects in the Insulator-Metal Phase Transition in VO2 Nano-Gap Junctions

DTIC Science & Technology

2014-11-27

VO2 , air, or SiO2, the 2 -0.50 -0.25 0.00 0.25 0.50 0 2 4 6 V Gap V App V o lt ag e (V ) time (ms) t p V I→M V M→I 100 400 700 1000 0.0 2.5 5.0 7.5...Electronic and thermal effects in the insulator-metal phase transition in VO2 nano-gap junctions Arash Joushaghani,1 Junho Jeong,1 Suzanne Paradis,2...Canada (Dated: 27 November 2014) By controlling the thermal transport of VO2 nano-gap junctions using device geometry, contact material, and applied

Nano scale dynamics of bubble nucleation in confined liquid subjected to rapid cooling: Effect of solid-liquid interfacial wettability

NASA Astrophysics Data System (ADS)

Hasan, Mohammad Nasim; Rabbi, Kazi Fazle; Mukut, K. M.; Tamim, Saiful Islam; Faisal, A. H. M.

2017-06-01

This study focuses on the occurrence of bubble nucleation in a liquid confined in a nano scale confinement and subjected to rapid cooling at one of its wall. Due to the very small size scale of the present problem, we adopt the molecular dynamics (MD) approach. The liquid (Argon) is confined within two solid (Platinum) walls. The temperature of the upper wall of the confinement is maintained at 90 K while the lower wall is being cooled rapidly to 50 K from initial equilibrium temperature of 90 K within 0.1 ns. This results in the nucleation and formation of nanobubbles in the liquid. The pattern of bubble nucleation has been studied for three different conditions of solid-liquid interfacial wettability such as hydrophilic, hydrophobic and neutral. Behavior of bubble nucleation is significantly different in the three case of solid-liquid interfacial wettability. In case of the hydrophobic confinement (weakly adsorbing), the liquid cannot achieve deeper metastability; vapor layers appear immediately on the walls. In case of the neutral confinement (moderately adsorbing), bubble nucleation is promoted by the walls where the nucleation is heterogeneous. In case of the hydrophilic walls (strongly adsorbing) bubbles are developed inside the liquid; that is the nucleation process is homogeneous. The variation in bubble nucleation under different conditions of surface wettability has been studied by the analysis of number density distribution, spatial temperature distribution, spatial number density distribution and heat flux through the upper and lower walls of the confinement. The present study indicates that the variation of heat transfer efficiency due to different surface wettability has significant effect on the size, shape and location of bubble nucleation in case rapid cooling of liquid in nano confinement.

The Effect of Nano Loading and Ultrasonic Compounding of EVA/LDPE/Nano-magnesium Hydroxide on Mechanical Properties and Distribution of Nano Particles

NASA Astrophysics Data System (ADS)

Azman, I. A.; Salleh, R. M.; Alauddin, S. M.; Shueb, M. I.

2018-05-01

Blends of Ethylene Vinyl Acetate (EVA) and Low-Density Polyethylene (LDPE) are promising composite which have good mechanical properties to environmental stress cracking. However, they lack fire resistant properties, which limits it usage in wire and cable industry. In order to improve flame retardancy ability, a range of nano-magnesium hydroxide (nano-MH) loading which is from 0 phr to maximum of 20 phr with ultrasonic extrusion 0-100 kHz frequencies have been introduced. Ultrasonic extrusion was used to improve the distribution of nano-MH. It was found that, 10 phr of nano loading with 100 kHz ultrasonic assisted has greater tensile strength compared to the nanocomposite without ultrasonication. Further increase of nano MH loading, will decrease the tensile properties. Better elongation at break was observed at10 phr nano-MH with the frequency of 50 kHz. The sample of 20 phr of nanoMH assisted with 50 kHz ultrasonic exhibits good flexural properties while 10 phr of nano-MH without the ultrasonic assisted demonstrates good in izod impact properties. From the evaluation of mechanical properties studied, it was found that 10 phr of nano-MH has shown the best performance among all the samples tested for EVA/LDPE/nano-MH composites. Transmission Electron Microscopy (TEM) has been conducted on 10 phr sample with different frequencies in order to observe the distribution of nano-MH particles. The sample with 100 kHz frequency shows more uniform dispersion of nano-MH in EVA/LDPE composites. This investigation indicates that the ultrasonic technology can enhance the mechanical properties studied as well as the dispersion of nano particles in the composite.