Growth of urea crystals by physical vapor transport

NASA Technical Reports Server (NTRS)

Feigelson, R. S.; Route, R. K.; Kao, T.-M.

1985-01-01

This work demonstrates that high optical quality crystals of urea can be grown by the physical vapor transport method. The unique features of this method are compared with growth from methanol/water solutions. High growth rates, exceeding 2.5 mm/day, were achieved, and cm-size optical quality single crystals were obtained. Details of the growth technique and the physical properties of the crystals are presented.

Soil physical and chemical properties associated with flat rock and riparian forest communities

Treesearch

David O. Mitchem; James E. Johnson; Laura S. Gellerstedt

2006-01-01

Flat Rock forest communities are unique ecosystems found adjacent to some large rivers in the Central and Southern Appalachian Mountains. Characterized by thin, alluvial soils overlying flat, resistant sandstone, these areas are maintained by severe flooding and have unique associated plant systems. With the advent of dams to control flooding in the 20th century, many...

Proliferative activity of elastin-like-peptides depends on charge and phase transition.

PubMed

Yuan, Yuan; Koria, Piyush

2016-03-01

Elastin-like-peptides (ELPs) are stimulus-responsive protein-based polymers and are attractive biomaterials due to their biocompatibility and unique properties. This study shows that in addition to their physical properties, ELPs have biological activities that are conducive to tissue regeneration. Specifically, we found that ELPs induce fibroblast proliferation via cell surface heparan sulfate proteoglycans (HSPG). Furthermore, our data suggests that ELP based materials with differential proliferative potential can be designed by controlling the interaction of ELPs with HSPGs by incorporating either hydrophobic or positively charged residues within the ELP sequence. Fibroblast proliferation is important for granulation tissue formation which is important in chronic wounds as well as in healing of other tissues. The customizable biological activity of ELPs coupled with their unique physical properties will enable us to design novel, sustainable and cost effective therapies for different tissue regeneration applications. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 697-706, 2016. © 2015 Wiley Periodicals, Inc.

The second evolution of ionic liquids: from solvents and separations to advanced materials--energetic examples from the ionic liquid cookbook.

PubMed

Smiglak, Marcin; Metlen, Andreas; Rogers, Robin D

2007-11-01

In this Account of the small portion of the recent research in ionic liquids (ILs) by the Rogers Group, we fast forward through the first evolution of IL research, where ILs were studied for their unique set of physical properties and the resulting potential for tunable "green solvents", to the second evolution of ILs, where the tunability of the cation and anion independently offers almost unlimited access to targeted combinations of physical and chemical properties. This approach is demonstrated here with the field of energetic ionic liquids (EILs), which utilizes this design flexibility to find safe synthetic routes to ILs with high energy content and targeted physical properties.

A study of physical properties of ODPA-p-PDA polyimide films

NASA Technical Reports Server (NTRS)

Singh, Jag J.; Eftekhari, Abe; St.clair, Terry L.

1990-01-01

Physical properties were investigated of ODPA-p-PDA polyimide films, including their lower molecular weight versions with phthalimide endcaps. Free volume, determined by low energy positron annihilation in the test films, was the major parameter of interest since all other physical properties are ostensibly related to it. It affects the dielectric constant as well as the saturation moisture pickup of the test films. An empirical relation was developed between the free volume and molecular weight of the test films, comparable to the Mark-Houwink relation between the polymer solution viscosity and the molecular weight. Development of such a relation constitutes a unique achievement since it enables researchers to estimate the molecular weight of an intractable polymer in solid state for the first time.

Copper-Zinc Superoxide Dismutase: A Unique Biological "Ligand" for Bioinorganic Studies.

ERIC Educational Resources Information Center

Valentine, Joan Selverstone; de Freitas, Duarte Mota

1985-01-01

Discusses superoxide dismutase (SOD) research and the properties of copper, zinc (Cu, Zn)-SOD. Emphasizes the controversy concerning the role of Cu,Zn-SOD and other SOD enzymes as protective agents in reactions involving dioxygen metabolism, and the properties of Cu, Zn-SOD that make it an interesting biological ligand for physical studies of…

Constraining properties of disintegrating exoplanets

NASA Astrophysics Data System (ADS)

Veras, D.; Carter, P. J.; Leinhardt, Z. M.; Gänsicke, B. T.

2017-09-01

Evaporating and disintegrating planets provide unique insights into chemical makeup and physical constraints. The striking variability, depth (˜10 - 60%) and shape of the photometric transit curves due to the disintegrating minor planet orbiting white dwarf WD 1145+017 has galvanised the post-main- sequence exoplanetary science community. We have performed the first tidal disruption simulations of this planetary object, and have succeeded in constraining its mass, density, eccentricity and physical nature. We illustrate how our simulations can bound these properties, and be used in the future for other exoplanetary systems.

Physics of epi-thermal boron neutron capture therapy (epi-thermal BNCT).

PubMed

Seki, Ryoichi; Wakisaka, Yushi; Morimoto, Nami; Takashina, Masaaki; Koizumi, Masahiko; Toki, Hiroshi; Fukuda, Mitsuhiro

2017-12-01

The physics of epi-thermal neutrons in the human body is discussed in the effort to clarify the nature of the unique radiologic properties of boron neutron capture therapy (BNCT). This discussion leads to the computational method of Monte Carlo simulation in BNCT. The method is discussed through two examples based on model phantoms. The physics is kept at an introductory level in the discussion in this tutorial review.

Physical dimensions, torsional performance, bending properties, and metallurgical characteristics of rotary endodontic instruments. VI. Canal Master drills.

PubMed

Luebke, N H; Brantley, W A; Sabri, Z I; Luebke, F L; Lausten, L L

1995-05-01

A laboratory study was performed on machine-driven Canal Master drills to determine their physical dimensions, torsional performance, bending properties, and metallurgical characteristics in fracture. Physical dimensions were determined for each of the available sizes (#50 to #100) of Canal Master drills from the manufacturer that distributes these instruments in the United States. Samples were also tested in clockwise torsion using a Maillefer memocouple. Bending properties of cantilever specimens were measured with a Tinius Olsen stiffness tester. Bending fatigue testing was performed on a unique laboratory apparatus. Scanning electron microscope examination confirmed visual observations that the stainless steel Canal Master drills exhibited ductile torsional fracture. This study is part of a continuing investigation to establish standards for all machine-driven rotary endodontic instruments.

Physics of cosmological cascades and observable properties

NASA Astrophysics Data System (ADS)

Fitoussi, T.; Belmont, R.; Malzac, J.; Marcowith, A.; Cohen-Tanugi, J.; Jean, P.

2017-04-01

TeV photons from extragalactic sources are absorbed in the intergalactic medium and initiate electromagnetic cascades. These cascades offer a unique tool to probe the properties of the universe at cosmological scales. We present a new Monte Carlo code dedicated to the physics of such cascades. This code has been tested against both published results and analytical approximations, and is made publicly available. Using this numerical tool, we investigate the main cascade properties (spectrum, halo extension and time delays), and study in detail their dependence on the physical parameters (extragalactic magnetic field, extragalactic background light, source redshift, source spectrum and beaming emission). The limitations of analytical solutions are emphasized. In particular, analytical approximations account only for the first generation of photons and higher branches of the cascade tree are neglected.

Constraints on pulsar masses from the maximum observed glitch

NASA Astrophysics Data System (ADS)

Pizzochero, P. M.; Antonelli, M.; Haskell, B.; Seveso, S.

2017-07-01

Neutron stars are unique cosmic laboratories in which fundamental physics can be probed in extreme conditions not accessible to terrestrial experiments. In particular, the precise timing of rotating magnetized neutron stars (pulsars) reveals sudden jumps in rotational frequency in these otherwise steadily spinning-down objects. These 'glitches' are thought to be due to the presence of a superfluid component in the star, and offer a unique glimpse into the interior physics of neutron stars. In this paper we propose an innovative method to constrain the mass of glitching pulsars, using observations of the maximum glitch observed in a star, together with state-of-the-art microphysical models of the pinning interaction between superfluid vortices and ions in the crust. We study the properties of a physically consistent angular momentum reservoir of pinned vorticity, and we find a general inverse relation between the size of the maximum glitch and the pulsar mass. We are then able to estimate the mass of all the observed glitchers that have displayed at least two large events. Our procedure will allow current and future observations of glitching pulsars to constrain not only the physics of glitch models but also the superfluid properties of dense hadronic matter in neutron star interiors.

Graphene based biosensors

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

Gürel, Hikmet Hakan, E-mail: hhakan.gurel@kocaeli.edu.tr; Salmankurt, Bahadır

2016-03-25

Nanometer-sized graphene as a 2D material has unique chemical and electronic properties. Because of its unique physical, chemical, and electronic properties, its interesting shape and size make it a promising nanomaterial in many biological applications. It is expected that biomaterials incorporating graphene will be developed for the graphene-based drug delivery systems and biomedical devices. The interactions of biomolecules and graphene are long-ranged and very weak. Development of new techniques is very desirable for design of bioelectronics sensors and devices. In this work, we present first-principles calculations within density functional theory to calculate effects of charging on nucleobases on graphene. Itmore » is shown that how modify structural and electronic properties of nucleobases on graphene by applied charging.« less

Cellulose Nanocrystal Entrapment of Benzalkonium Chloride in Southern Pine: Biological, Chemical, and Physical Properties

Treesearch

Carol A. Clausen; Vina W. Yang; Rachel A. Arango; Laura E. Hasburgh; Patricia K. Lebow; Richard S. Reiner

2015-01-01

Protecting wood products from biodeterioration has been a dynamic area of research in the past decade with an emphasis on the development of non-arsenical wood preservatives. Naturally occurring cellulose nanomaterials that are reported to have unique chemical properties, high strength, and stiffness were evaluated for the potential to improve durability of wood either...

Physical Oceanography: Project Earth Science. Material for Middle School Teachers in Earth Science.

ERIC Educational Resources Information Center

Ford, Brent A.; Smith, P. Sean

This book is one in a series of Earth science books and contains a collection of 18 hands-on activities/demonstrations developed for the middle/junior high school level. The activities are organized around three key concepts. First, students investigate the unique properties of water and how these properties shape the ocean and the global…

Neither Animal Nor Vegetable.

ERIC Educational Resources Information Center

Freas, Carol

1991-01-01

Presented are interdisciplinary activities that help students to identify minerals and to begin to understand the properties that make each one unique. The concept of individuality is emphasized. Included is a section on minerals and an explanation of their physical characteristics. (KR)

Computational and Physical Analysis of Catalytic Compounds

NASA Astrophysics Data System (ADS)

Wu, Richard; Sohn, Jung Jae; Kyung, Richard

2015-03-01

Nanoparticles exhibit unique physical and chemical properties depending on their geometrical properties. For this reason, synthesis of nanoparticles with controlled shape and size is important to use their unique properties. Catalyst supports are usually made of high-surface-area porous oxides or carbon nanomaterials. These support materials stabilize metal catalysts against sintering at high reaction temperatures. Many studies have demonstrated large enhancements of catalytic behavior due to the role of the oxide-metal interface. In this paper, the catalyzing ability of supported nano metal oxides, such as silicon oxide and titanium oxide compounds as catalysts have been analyzed using computational chemistry method. Computational programs such as Gamess and Chemcraft has been used in an effort to compute the efficiencies of catalytic compounds, and bonding energy changes during the optimization convergence. The result illustrates how the metal oxides stabilize and the steps that it takes. The graph of the energy computation step(N) versus energy(kcal/mol) curve shows that the energy of the titania converges faster at the 7th iteration calculation, whereas the silica converges at the 9th iteration calculation.

Ultrathin Ferroelectric Films: Growth, Characterization, Physics and Applications.

PubMed

Wang, Ying; Chen, Weijin; Wang, Biao; Zheng, Yue

2014-09-11

Ultrathin ferroelectric films are of increasing interests these years, owing to the need of device miniaturization and their wide spectrum of appealing properties. Recent advanced deposition methods and characterization techniques have largely broadened the scope of experimental researches of ultrathin ferroelectric films, pushing intensive property study and promising device applications. This review aims to cover state-of-the-art experimental works of ultrathin ferroelectric films, with a comprehensive survey of growth methods, characterization techniques, important phenomena and properties, as well as device applications. The strongest emphasis is on those aspects intimately related to the unique phenomena and physics of ultrathin ferroelectric films. Prospects and challenges of this field also have been highlighted.

Ultrathin Ferroelectric Films: Growth, Characterization, Physics and Applications

PubMed Central

Wang, Ying; Chen, Weijin; Wang, Biao; Zheng, Yue

2014-01-01

Ultrathin ferroelectric films are of increasing interests these years, owing to the need of device miniaturization and their wide spectrum of appealing properties. Recent advanced deposition methods and characterization techniques have largely broadened the scope of experimental researches of ultrathin ferroelectric films, pushing intensive property study and promising device applications. This review aims to cover state-of-the-art experimental works of ultrathin ferroelectric films, with a comprehensive survey of growth methods, characterization techniques, important phenomena and properties, as well as device applications. The strongest emphasis is on those aspects intimately related to the unique phenomena and physics of ultrathin ferroelectric films. Prospects and challenges of this field also have been highlighted. PMID:28788196

Wool shrinkproofing by chemical and ezymatic methods

USDA-ARS?s Scientific Manuscript database

The uniqueness of wool, its functionality, morphology, physical/ mechanical behavior, and aesthetics, continue to be topics for innovative research to improve properties and create novel products. The perennial problems of yellowness, discomfort in wear, and shrinkage have been addressed over time ...

Ni-Ti Alloys for Aerospace Bearing Applications

NASA Technical Reports Server (NTRS)

DellaCorte, Christopher

2017-01-01

Nickel-rich Ni-Ti alloys are emerging candidate materials for aerospace bearing applications. These alloys exhibit a unique combination of physical, chemical, and tribological properties that are highly relevant to challenging aerospace bearings and other mechanical components. Despite being made solely from metals, Ni-Ti alloys are classified as intermetallics with properties akin to both metals and ceramics. For instance, like metals, they are electrically conductive but they tend to be brittle like ceramics. When properly processed, they have high hardness, low elastic modulus and an extensive elastic deformation range that imparts extraordinarily high resilience and resistance to denting. New alloy compositions enable simpler thermal processing and machining and intensive microstructural analyses have helped elucidate the materials science mechanisms governing hardness. In this paper, the application of state-of-art in NiTi alloys for aerospace bearings and mechanical components is explored. In addition to reviewing future trends and remaining challenges, the unique approaches and methods of tailoring bearing design to accommodate NiTis unique properties is discussed.

Biocatalytic production of D-tagatose: A potential rare sugar with versatile applications.

PubMed

Jayamuthunagai, J; Gautam, P; Srisowmeya, G; Chakravarthy, M

2017-11-02

D-tagatose is a naturally existing rare monosaccharide having prebiotic properties. Minimal absorption, low metabolizing energy, and unique clinical properties are the characteristics of D-tagatose. D-tagatose gained international attention by matching the purpose of alternate sweeteners that is much needed for the control of diabetes among world population. Recent efforts in understanding tagatose bioconversion have generated essential information regarding its production and application. This article reviews the evolution of D-tagatose as an important rare sugar by appreciable improvements in production results and its significant applications resulted of its unique physical, chemical, biological, and clinical properties thus considering it an appropriate product for requisite improvements in technical viability. Based on current knowledge and technology projections, the commercialization of D-tagatose rare sugar as food additive is close to reality.

Exploitation of Unique Properties of Zeolites in the Development of Gas Sensors

PubMed Central

Zheng, Yangong; Li, Xiaogan; Dutta, Prabir K.

2012-01-01

The unique properties of microporous zeolites, including ion-exchange properties, adsorption, molecular sieving, catalysis, conductivity have been exploited in improving the performance of gas sensors. Zeolites have been employed as physical and chemical filters to improve the sensitivity and selectivity of gas sensors. In addition, direct interaction of gas molecules with the extraframework cations in the nanoconfined space of zeolites has been explored as a basis for developing new impedance-type gas/vapor sensors. In this review, we summarize how these properties of zeolites have been used to develop new sensing paradigms. There is a considerable breadth of transduction processes that have been used for zeolite incorporated sensors, including frequency measurements, optical and the entire gamut of electrochemical measurements. It is clear from the published literature that zeolites provide a route to enhance sensor performance, and it is expected that commercial manifestation of some of the approaches discussed here will take place. The future of zeolite-based sensors will continue to exploit its unique properties and use of other microporous frameworks, including metal organic frameworks. Zeolite composites with electronic materials, including metals will lead to new paradigms in sensing. Use of nano-sized zeolite crystals and zeolite membranes will enhance sensor properties and make possible new routes of miniaturized sensors. PMID:22666081

Carbon-Based Nanomaterials: Multi-Functional Materials for Biomedical Engineering

PubMed Central

Cha, Chaenyung; Shin, Su Ryon; Annabi, Nasim; Dokmeci, Mehmet R.; Khademhosseini, Ali

2013-01-01

Functional carbon-based nanomaterials (CBNs) have become important due to their unique combinations of chemical and physical properties (i.e., thermal and electrical conductivity, high mechanical strength, and optical properties), extensive research efforts are being made to utilize these materials for various industrial applications, such as high-strength materials and electronics. These advantageous properties of CBNs are also actively investigated in several areas of biomedical engineering. This Perspective highlights different types of carbon-based nanomaterials currently used in biomedical applications. PMID:23560817

Carbon-based nanomaterials: multifunctional materials for biomedical engineering.

PubMed

Cha, Chaenyung; Shin, Su Ryon; Annabi, Nasim; Dokmeci, Mehmet R; Khademhosseini, Ali

2013-04-23

Functional carbon-based nanomaterials (CBNs) have become important due to their unique combinations of chemical and physical properties (i.e., thermal and electrical conductivity, high mechanical strength, and optical properties), and extensive research efforts are being made to utilize these materials for various industrial applications, such as high-strength materials and electronics. These advantageous properties of CBNs are also actively investigated in several areas of biomedical engineering. This Perspective highlights different types of carbon-based nanomaterials currently used in biomedical applications.

Magnetic and Optical Properties of Submicron-Size Hollow Spheres

PubMed Central

Ye, Quan-Lin; Yoshikawa, Hirofumi; Awaga, Kunio

2010-01-01

Magnetic hollow spheres with a controlled diameter and shell thickness have emerged as an important class of magnetic nanomaterials. The confined hollow geometry and pronouncedly curved surfaces induce unique physical properties different from those of flat thin films and solid counterparts. In this paper, we focus on recent progress on submicron-size spherical hollow magnets (e.g., cobalt- and iron-based materials), and discuss the effects of the hollow shape and the submicron size on magnetic and optical properties.

Protein based Block Copolymers

PubMed Central

Rabotyagova, Olena S.; Cebe, Peggy; Kaplan, David L.

2011-01-01

Advances in genetic engineering have led to the synthesis of protein-based block copolymers with control of chemistry and molecular weight, resulting in unique physical and biological properties. The benefits from incorporating peptide blocks into copolymer designs arise from the fundamental properties of proteins to adopt ordered conformations and to undergo self-assembly, providing control over structure formation at various length scales when compared to conventional block copolymers. This review covers the synthesis, structure, assembly, properties, and applications of protein-based block copolymers. PMID:21235251

The alloy with a memory, 55-Nitinol: Its physical metallurgy, properties, and applications

NASA Technical Reports Server (NTRS)

Jackson, C. M.; Wagner, H. J.; Wasilewski, R. J.

1972-01-01

A series of nickel titanium alloys (55-Nitinol), which are unique in that they possess a shape memory, are described. Components made of these materials that are altered in their shapes by deformation under proper conditions return to predetermined shapes when they are heated to the proper temperature range. The shape memory, together with the force exerted and the ability of the material to do mechanical work as it returns to its predetermined shape, suggest a wide variety of industrial applications for the alloy. Also included are discussions of the physical metallurgy and the mechanical, physical, and chemical properties of 55-Nitinol; procedures for melting and processing the material into useful shapes; and a summary of applications.

The unique radar scattering properties of silicic lava flows and domes

NASA Technical Reports Server (NTRS)

Plaut, Jeffrey J.; Stofan, Ellen R.; Anderson, Steven W.; Crown, David A.

1995-01-01

Silicic (silica-rich) lava flows, such as rhyolite, rhyodacite, and dacite, possess unique physical properties primarily because of the relatively high viscosity of the molten lava. Silicic flows tend to be thicker than basaltic flows, and the resulting large-scale morphology is typically a steep-sided dome or flow lobe, with aspect ratios (height/length) sometimes approaching unity. The upper surfaces of silicic domes and flows are normally emplaced as relatively cool, brittle slabs that fracture as they are extruded from the central vent areas, and are then rafted away toward the flow margin as a brittle carapace above a more ductile interior layer. This mode of emplacement results in a surface with unique roughness characteristics, which can be well-characterized by multiparameter synthetic aperture radar (SAR) observations. In this paper, we examine the scattering properties of several silicic domes in the Inyo volcanic chain in the Eastern Sierra of California, using AIRSAR and TOPSAR data. Field measurements of intermediate-scale (cm to tens of m) surface topography and block size are used to assess the mechanisms of the scattering process, and to quantify the unique roughness characteristics of the flow surfaces.

Measurement of Physical and Hydraulic Properties of Organic Soil Using Computed Tomographic Imagery

NASA Astrophysics Data System (ADS)

Blais, K. E.; Quinton, W. L.; Heck, R. J.; Price, J. S.; Schmidt, M. G.

2005-12-01

The Lower Liard River valley is located within the continental northern boreal region and the zone of discontinuous permafrost. Lying in the centre of the Mackenzie basin, this valley is an extensive flat headwater region with a high density of open water and peatlands. Several standard methods of measuring the physical properties of organic soils exist, although many of them have several drawbacks that limit their use. Organic soils, in particular, have unique properties that require special attention to ensure that the measured hydrological characteristics are represented as they exist in nature. The goal of this research was to devise an improved method of analyzing and measuring the physical and hydraulic properties of organic soil using MicroCT imagery. Specifically, this research seeks to determine if two and three-dimensional images of peat can be used to accurately characterize air-filled porosity, active porosity, pore size distribution, pore saturated area and capillarity of porous Sphagnum cells. Results indicate that measurements derived from these images are consistent with current literature. They also suggest that this non-destructive method is a valuable tool for measuring peat physical and hydraulic properties and that there is potential for additional research using CT technology.

Actuators Based on Liquid Crystalline Elastomer Materials

PubMed Central

Jiang, Hongrui; Li, Chensha; Huang, Xuezhen

2013-01-01

Liquid crystalline elastomers (LCEs) exhibit a number of remarkable physical effects, including the unique, high-stroke reversible mechanical actuation when triggered by external stimuli. This article reviews some recent exciting developments in the field of LCEs materials with an emphasis on their utilization in actuator applications. Such applications include artificial muscles, industrial manufacturing, health and microelectromechanical systems (MEMS). With suitable synthetic and preparation pathways and well-controlled actuation stimuli, such as heat, light, electric and magnetic field, excellent physical properties of LCE materials can be realized. By comparing the actuating properties of different systems, general relationships between the structure and the property of LCEs are discussed. How these materials can be turned into usable devices using interdisciplinary techniques is also described. PMID:23648966

Actuators based on liquid crystalline elastomer materials

NASA Astrophysics Data System (ADS)

Jiang, Hongrui; Li, Chensha; Huang, Xuezhen

2013-05-01

Liquid crystalline elastomers (LCEs) exhibit a number of remarkable physical effects, including the unique, high-stroke reversible mechanical actuation when triggered by external stimuli. This article reviews some recent exciting developments in the field of LCE materials with an emphasis on their utilization in actuator applications. Such applications include artificial muscles, industrial manufacturing, health and microelectromechanical systems (MEMS). With suitable synthetic and preparation pathways and well-controlled actuation stimuli, such as heat, light, electric and magnetic fields, excellent physical properties of LCE materials can be realized. By comparing the actuating properties of different systems, general relationships between the structure and the properties of LCEs are discussed. How these materials can be turned into usable devices using interdisciplinary techniques is also described.

Physical and chemical characterization of waste wood derived biochars

USDA-ARS?s Scientific Manuscript database

Biochar, a solid byproduct generated during waste biomass pyrolysis or gasification in the absence (or near-absence) of oxygen, has recently garnered interest for both agricultural and environmental management purposes owing to its unique physicochemical properties, such as its high surface area and...

Can Biochar Covers Reduce Emissions from Manure Lagoons While Capturing Nutrients?

EPA Science Inventory

The unique physical and chemical properties of biochars make them promising materials for odor, gas, and nutrient sorption. Floating covers made from organic materials (biocovers) are one option for reducing odor and gas emissions from livestock manure lagoons. This study evaluat...

Tailored nanoporous coatings fabricated on conformable polymer substrates.

PubMed

Poxson, David J; Mont, Frank W; Cho, Jaehee; Schubert, E Fred; Siegel, Richard W

2012-11-01

Nanoporous coatings have become the subject of intense investigation, in part because they have been shown to have unique and tailorable physical properties that can depart greatly from their dense or macroscopic counterparts. Nanoporous coatings are frequently fabricated utilizing oblique-angle or glancing-angle physical vapor-phase deposition techniques. However, a significant limitation for such coatings exists; they are almost always deposited on smooth and rigid planar substrates, such as silicon and glass. This limitation greatly constrains the applicability, tailorability, functionality and even the economic viability, of such nanoporous coatings. Here, we report our findings on nanoporous/polymer composite systems (NPCS) fabricated by utilizing oblique-angle electron-beam methodology. These unique composite systems exhibit several favorable characteristics, namely, (i) fine-tuned control over coating nanoporosity and thickness, (ii) excellent adhesion between the nanoporous coating and polymer substrate, (iii) the ability to withstand significant and repeated bending, and (iv) the ability to be molded conformably on two and three-dimensional surfaces while closely retaining the composite system's designed nanoporous film structure and, hence, properties.

Smart Materials Based on DNA Aptamers: Taking Aptasensing to the Next Level

PubMed Central

Mastronardi, Emily; Foster, Amanda; Zhang, Xueru; DeRosa, Maria C.

2014-01-01

“Smart” materials are an emerging category of multifunctional materials with physical or chemical properties that can be controllably altered in response to an external stimulus. By combining the standard properties of the advanced material with the unique ability to recognize and adapt in response to a change in their environment, these materials are finding applications in areas such as sensing and drug delivery. While the majority of these materials are responsive to physical or chemical changes, a particularly exciting area of research seeks to develop smart materials that are sensitive to specific molecular or biomolecular stimuli. These systems require the integration of a molecular recognition probe specific to the target molecule of interest. The ease of synthesis and labeling, low cost, and stability of DNA aptamers make them uniquely suited to effectively serve as molecular recognition probes in novel smart material systems. This review will highlight current work in the area of aptamer-based smart materials and prospects for their future applications. PMID:24553083

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

Sloman, David L.; Noucti, Njamkou; Altman, Michael D.

Inhibition of microtubule affinity regulating kinase (MARK) represents a potentially attractive means of arresting neurofibrillary tangle pathology in Alzheimer’s disease. This manuscript outlines efforts to optimize a pyrazolopyrimidine series of MARK inhibitors by focusing on improvements in potency, physical properties and attributes amenable to CNS penetration. A unique cylcyclohexyldiamine scaffold was identified that led to remarkable improvements in potency, opening up opportunities to reduce MW, Pgp efflux and improve pharmacokinetic properties while also conferring improved solubility.

Volcanic-ash-derived forest soils of the inland Northwest: Properties and implications for management and restoration

Treesearch

Deborah Page-Dumroese; Richard Miller; Jim Mital; Paul McDaniel; Dan Miller

2007-01-01

Volcanic ash from the eruption of Mt. Mazama ~7,700 years ago has a strong influence on many forested landscapes of the Pacific Northwest and Intermountain regions of the USA and Canada. Because of the unique biological, physical and chemical properties of the ash, it is closely tied to plant communities and forest productivity, and should therefore be considered as a...

Influence of Zwitterions on Thermomechanical Properties and Morphology of Acrylic Copolymers: Implications for Electroactive Applications

DTIC Science & Technology

2011-09-30

transducers from branched sulfonated polysulfones.7 The mechanical strength of the membranes drastically decreased upon introduction of ionic liquids to... liquids ,8 and zwitterionomers maintained mechanical strengths upon swelling with 10 wt % ionic liquid . Zwitterions are chargedmolecules that contain...water purification5 to biotechnology.6 A unique combination of physical properties of ionomeric membranes is the ionic con- ductivity of lowmolar mass

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

Antropov, Vladimir P; Antonov, Victor N

We present a first-principles investigation of the electronic structure and physical properties of doped lithium nitridometalates Li 2(Li 1-xM x)N (LiMN) with M = Cr, Mn, Fe, Co, and Ni. The diverse properties include the equilibrium magnetic moments, magneto-crystalline anisotropy, magneto-optical Kerr spectra, and x-ray magnetic circular dichroism. We explain the colossal magnetic anisotropy in LiFeN by its unique electronic structure which ultimately leads to a series of unusual physical properties. The most unique property is a complete suppression of relativistic effects and freezing of orbital moments for in-plane orientation of the magnetization. This leads to the colossal spatial anisotropymore » of many magnetic properties including energy, Kerr, and dichroism effects. LiFeN is identified as an ultimate single-ion anisotropy system where a nearly insulating state can be produced by a spin orbital coupling alone. A very nontrivial strongly fluctuating and sign changing character of the magnetic anisotropy with electronic 3d-atomic doping is predicted theoretically. A large and highly anisotropic Kerr effect due to the interband transitions between atomic-like Fe 3d bands is found for LiFeN. A giant anisotropy of the x-ray magnetic circular dichroism for the Fe K spectrum and a very weak one for the Fe L 2,3 spectra in LiFeN are also predicted.« less

Explosive Welding in the 1990's

NASA Technical Reports Server (NTRS)

Lalwaney, N. S.; Linse, V. D.

1985-01-01

Explosive bonding is a unique joining process with the serious potential to produce composite materials capable of fulfilling many of the high performance materials capable of fulfilling many of the high performance materials needs of the 1990's. The process has the technological versatility to provide a true high quality metallurgical compatible and incompatible systems. Metals routinely explosively bonded include a wide variety of combinations of reactive and refractory metals, low and high density metals and their alloys, corrosion resistant and high strength alloys, and common steels. The major advantage of the process is its ability to custom design and engineer composites with physical and/or mechanical properties that meet a specific or unusual performance requirement. Explosive bonding offers the designer unique opportunities in materials selection with unique combinations of properties and high integrity bonds that cannot be achieved by any other metal joining process. The process and some applications are discussed.

Effect of Sintering on Mechanical and Physical Properties of Plasma-Sprayed Thermal Barrier Coatings

NASA Technical Reports Server (NTRS)

Choi, Sung R.; Zhu, Dong-Ming; Miller, Robert A.

2004-01-01

The effect of sintering on mechanical and physical properties of free-standing plasma-sprayed ZrO2-8 wt% Y2O3 thermal barrier coatings (TBCs) was determined by annealing them at 1316 C in air. Mechanical and physical properties of the TBCs, including strength, modes I and II fracture toughness, elastic modulus, Poisson s response, density, microhardness, fractography, and phase stability, were determined at ambient temperature as a function of annealing time ranging from 0 to 500 h. All mechanical and physical properties, except for the amount of monoclinic phase, increased significantly in 5 to 100 h and then reached a plateau above 100 h. Annealing resulted in healing of microcracks and pores and in grain growth, accompanying densification of the TBC s body due to the sintering effect. However, an inevitable adverse effect also occurred such that the desired lower thermal conductivity and good expansivity, which makes the TBCs unique in thermal barrier applications, were degraded upon annealing. A model was proposed to assess and quantify all the property variables in response to annealing in a normalized scheme. Directionality of as-sprayed TBCs appeared to have an insignificant effect on their properties, as determined via fracture toughness, microhardness, and elastic modulus measurements.

Synthesis of silver nanoparticles: chemical, physical and biological methods

PubMed Central

Iravani, S.; Korbekandi, H.; Mirmohammadi, S.V.; Zolfaghari, B.

2014-01-01

Silver nanoparticles (NPs) have been the subjects of researchers because of their unique properties (e.g., size and shape depending optical, antimicrobial, and electrical properties). A variety of preparation techniques have been reported for the synthesis of silver NPs; notable examples include, laser ablation, gamma irradiation, electron irradiation, chemical reduction, photochemical methods, microwave processing, and biological synthetic methods. This review presents an overview of silver nanoparticle preparation by physical, chemical, and biological synthesis. The aim of this review article is, therefore, to reflect on the current state and future prospects, especially the potentials and limitations of the above mentioned techniques for industries. PMID:26339255

Dimensional analysis yields the general second-order differential equation underlying many natural phenomena: the mathematical properties of a phenomenon's data plot then specify a unique differential equation for it.

PubMed

Kepner, Gordon R

2014-08-27

This study uses dimensional analysis to derive the general second-order differential equation that underlies numerous physical and natural phenomena described by common mathematical functions. It eschews assumptions about empirical constants and mechanisms. It relies only on the data plot's mathematical properties to provide the conditions and constraints needed to specify a second-order differential equation that is free of empirical constants for each phenomenon. A practical example of each function is analyzed using the general form of the underlying differential equation and the observable unique mathematical properties of each data plot, including boundary conditions. This yields a differential equation that describes the relationship among the physical variables governing the phenomenon's behavior. Complex phenomena such as the Standard Normal Distribution, the Logistic Growth Function, and Hill Ligand binding, which are characterized by data plots of distinctly different sigmoidal character, are readily analyzed by this approach. It provides an alternative, simple, unifying basis for analyzing each of these varied phenomena from a common perspective that ties them together and offers new insights into the appropriate empirical constants for describing each phenomenon.

MERTIS — Unleashing the Power of the Thermal Infrared on Mercury

NASA Astrophysics Data System (ADS)

Helbert, J.; Maturilli, A.; D'Amore, M.; Varatharajan, I.; Hiesinger, H.; Mertis Team

2018-05-01

MERTIS combines an imaging spectrometer (7-14 μm at 500m spatial resolution) with a radiometer (7 to 40 μm at 2km). The compositional, temperature and thermo-physical properties maps provided will allow unique insights into the evolution of Mercury.

JUDGING PUBLIC RISK - NOT ALL ARSENICS ARE CREATED EQUAL

EPA Science Inventory

Many trace elements occur in the environment in several chemical forms, called species. Each species has unique physical-chemical properties that affect how it moves in the environment, as well as how available and toxic it is to humans and other animals. Hyphenated techniques, t...

2013-2014 Production of guayule natural rubber in Arizona, U.S.A.

USDA-ARS?s Scientific Manuscript database

Natural rubber is a unique biopolymer whose physical properties cannot be replicated in synthetic alternatives; therefore, it is required for production of tires (passenger, truck, and aircraft) and thousands of consumer and medical products. While demand for natural rubber is expected to increase ...

Electrochromic WO[subscript 3] Films: Nanotechnology Experiments in Instrumental Analysis and Physical Chemistry Laboratories

ERIC Educational Resources Information Center

Hepel, Maria

2008-01-01

This experiment teaches students the methodology of investigating novel properties of materials using new instrumental techniques: atomic force microscopy (AFM), electrochemical quartz crystal nanobalance (EQCN), voltammetric techniques (linear potential scan and chronoamperometry), and light reflectance measurements. The unique capabilities of…

The Imaging X-Ray Polarimetry Explorer (IXPE)

NASA Technical Reports Server (NTRS)

Weisskopf, Martin C.; Ramsey, Brian; O’Dell, Stephen; Tennant, Allyn; Elsner, Ronald; Soffita, Paolo; Bellazzini, Ronaldo; Costa, Enrico; Kolodziejczak, Jeffery; Kaspi, Victoria;

Probing physical properties at the nanoscale using atomic force microscopy

NASA Astrophysics Data System (ADS)

Ditzler, Lindsay Rachel

Techniques that measure physical properties at the nanoscale with high sensitivity are significantly limited considering the number of new nanomaterials being developed. The development of atomic force microscopy (AFM) has lead to significant advancements in the ability to characterize physical properties of materials in all areas of science: chemistry, physics, engineering, and biology have made great scientific strides do to the versatility of the AFM. AFM is used for quantification of many physical properties such as morphology, electrical, mechanical, magnetic, electrochemical, binding interactions, and protein folding. This work examines the electrical and mechanical properties of materials applicable to the field of nano-electronics. As electronic devices are miniaturized the demand for materials with unique electrical properties, which can be developed and exploited, has increased. For example, discussed in this work, a derivative of tetrathiafulvalene, which exhibits a unique loss of conductivity upon compression of the self-assembled monolayer could be developed into a molecular switch. This work also compares tunable organic (tetraphenylethylene tetracarboxylic acid and bis(pyridine)s assemblies) and metal-organic (Silver-stilbizole coordination compounds) crystals which show high electrical conductivity. The electrical properties of these materials vary depending on their composition allowing for the development of compositionally tunable functional materials. Additional work was done to investigate the effects of molecular environment on redox active 11-ferroceneyl-1 undecanethiol (Fc) molecules. The redox process of mixed monolayers of Fc and decanethiol was measured using conductive probe atomic force microscopy and force spectroscopy. As the concentration of Fc increased large, variations in the force were observed. Using these variations the number of oxidized molecules in the monolayer was determined. AFM is additionally capable of investigating interactions at the nanoscale, such as ligand-receptor interactions. This work examines the interactions between the enzyme dihydrofolate reductase (DHFR), a widely investigated enzyme targeted for cancer and antimicrobial pharmaceutical, and methotrexate (MTX), a strong competitive inhibitor of DHFR. The DHFR was immobilized on a gold substrate, bound through a single surface cysteine, and maintained catalytic activity. AFM probe was functionalized with MTX and the interaction strength was measured using AFM. This work highlights the versatility of AFM, specifically force spectroscopy for the quantification of electrical, mechanical, and ligand-receptor interactions at the nanoscale.

Physical properties of beeswax, sunflower wax, and candelilla wax mixtures and organogels

USDA-ARS?s Scientific Manuscript database

There is increased interest in natural waxes as alternatives to partially hydrogenated oils and saturated fats as oil structuring agents. Using relatively low concentrations (0.5-5%), natural waxes are able to form crystalline networks, or organogels, which bind liquid oil. Each natural wax is uniqu...

Evaluating the effect of tillage on soil structural properties using the pedostructure concept

USDA-ARS?s Scientific Manuscript database

The pedostructure (PS) concept is a physically-based method of soil characterization that defines a soil based on its structure and the relationship between structure and soil water behavior. There are fifteen unique pedostructure parameters that define the macropore and micropore soil water behavio...

The effects of microfluidization on the physical, microbial, chemical, and coagulation properties of milk

USDA-ARS?s Scientific Manuscript database

This work examines the use of mild heat treatments in conjunction with multiple pass microfluidization to generate unique cheesemilk for potential use in soft cheeses such as Queso Fresco and Cottage Cheese. Raw, thermized, and high temperature, short time pasteurized milk samples, standardized to ...

Utilization of agricultural biomass in the production of the biopolymer schizophyllan

USDA-ARS?s Scientific Manuscript database

Schizophyllan is a homoglucan produced by the fungus Schizophyllum commune, with a ß-1,3-linked backbone and ß-1,6-linked side chains of single glucose units at every other residue. Schizophyllan is commercially produced for pharmaceutical and cosmetics uses. However, the unique physical propertie...

The NanoSustain and NanoValid project--two new EU FP7 research initiatives to assess the unique physical-chemical and toxicological properties of engineered nanomaterials.

PubMed

Reuther, Rudolf

2011-02-01

In 2010, the EU FP NanoSustain project (247989) has been successfully launched with the objective to develop innovative solutions for the sustainable use, recycling and final treatment of engineered nanomaterials (ENMs). The same year, NanoValid (263147), a large-scale integrating EU FP7 project has been initiated and contract negotiations with the European Commission commenced, to develop new reference methods and materials applicable to the unique properties of ENMs. The paper presented will give an overview on the main objectives of these 2 new European research initiatives, on main tasks to achieve objectives, and on the impact on current standardization efforts and technical innovations.

Nanostructured Metal Oxides for Stoichiometric Degradation of Chemical Warfare Agents.

PubMed

Štengl, Václav; Henych, Jiří; Janoš, Pavel; Skoumal, Miroslav

2016-01-01

Metal oxides have very important applications in many areas of chemistry, physics and materials science; their properties are dependent on the method of preparation, the morphology and texture. Nanostructured metal oxides can exhibit unique characteristics unlike those of the bulk form depending on their morphology, with a high density of edges, corners and defect surfaces. In recent years, methods have been developed for the preparation of metal oxide powders with tunable control of the primary particle size as well as of a secondary particle size: the size of agglomerates of crystallites. One of the many ways to take advantage of unique properties of nanostructured oxide materials is stoichiometric degradation of chemical warfare agents (CWAs) and volatile organic compounds (VOC) pollutants on their surfaces.

Material Property Characterization of Potential Nanocarbon Metal-Matrix Composite: An Investigational Study

NASA Astrophysics Data System (ADS)

Zavala, Mitchel

Metal-matrix composites (MMCs) are engineered combinations of two or more materials. Tailored properties are achieved by systematic combinations of different constituents. Specialized design and synthesis procedures allow unique sets of material properties in composites. Covetics are a new type of metal-matrix nano-composite (MMnC) material. These materials are formed from FCC metals which are super-saturated with up to 10 wt. % of activated nano-carbon powder. The idea is that the nano-carbon particles will enhance the material properties of the base metal matrix, however most of the physical and mechanical properties of covetics have not been well characterized. The foci of this study are to optimize the covetic casting synthesis process under controlled conditions, to understand and analyze the microstructures of the synthesized copper and aluminum covetic, to provide a thorough analysis of the chemical composition of the synthesized covetic materials, and to characterize physical and mechanical properties of both of these materials using meticulously prepared samples and test procedures.

Terrestrial analogues for lunar impact melt flows

NASA Astrophysics Data System (ADS)

Neish, C. D.; Hamilton, C. W.; Hughes, S. S.; Nawotniak, S. Kobs; Garry, W. B.; Skok, J. R.; Elphic, R. C.; Schaefer, E.; Carter, L. M.; Bandfield, J. L.; Osinski, G. R.; Lim, D.; Heldmann, J. L.

2017-01-01

Lunar impact melt deposits have unique physical properties. They have among the highest observed radar returns at S-Band (12.6 cm wavelength), implying that they are rough at the decimeter scale. However, they are also observed in high-resolution optical imagery to be quite smooth at the meter scale. These characteristics distinguish them from well-studied terrestrial analogues, such as Hawaiian pāhoehoe and ´a´ā lava flows. The morphology of impact melt deposits can be related to their emplacement conditions, so understanding the origin of these unique surface properties will help to inform us as to the circumstances under which they were formed. In this work, we seek to find a terrestrial analogue for well-preserved lunar impact melt flows by examining fresh lava flows on Earth. We compare the radar return and high-resolution topographic variations of impact melt flows to terrestrial lava flows with a range of surface textures. The lava flows examined in this work range from smooth Hawaiian pāhoehoe to transitional basaltic flows at Craters of the Moon (COTM) National Monument and Preserve in Idaho to rubbly and spiny pāhoehoe-like flows at the recent eruption at Holuhraun in Iceland. The physical properties of lunar impact melt flows appear to differ from those of all the terrestrial lava flows studied in this work. This may be due to (a) differences in post-emplacement modification processes or (b) fundamental differences in the surface texture of the melt flows due to the melts' unique emplacement and/or cooling environment. Information about the surface properties of lunar impact melt deposits will be critical for future landed missions that wish to sample these materials.

Modelling of the mechanical behavior of a polyurethane finger interphalangeal joint endoprosthesis after surface modification by ion implantation

NASA Astrophysics Data System (ADS)

Beliaev, A.; Svistkov, A.; Iziumov, R.; Osorgina, I.; Kondyurin, A.; Bilek, M.; McKenzie, D.

2016-04-01

Production of biocompatible implants made of polyurethane treated with plasma is very perspective. During plasma treatment the surface of polyurethane acquires unique physic-chemical properties. However such treatment may change the mechanical properties of polyurethane which may adversely affect the deformation behaviour of the real implant. Therefore careful study of the mechanical properties of the plasma-modified polyurethane is needed. In this paper, experimental observations of the elastic characteristics of plasma treated polyurethane and modelling of the deformation behaviour of polyurethane bio-implants are reported.

Toxic and Beneficial Potential of Silver Nanoparticles: The Two Sides of the Same Coin.

PubMed

Souza, Lilian Rodrigues Rosa; da Silva, Veronica Santana; Franchi, Leonardo Pereira; de Souza, Tiago Alves Jorge

2018-01-01

Nanotechnology has allowed great changes in chemical, biological and physical properties of metals when compared to their bulk counterparts. Within this context, silver nanoparticles (AgNPs) play a major role due to their unique properties, being widely used in daily products such as fabrics, washing machines, water filters, food and medicine. However, AgNPs can enter cells inducing a "Trojan-horse" type mechanism which potentially leads to cellular autophagy, apoptosis or necrosis. On the other hand, this cytotoxicity mechanism can be optimized to develop drug nanocarriers and anticancer therapies. The increasing use of these NPs entails their release into the environment, damaging ecosystems balance and representing a threat to human health. In this context, the possible deleterious effects that these NPs may represent for the biotic and abiotic ecosystems components represent an obstacle that must be overcome in order to guarantee the safety use of their unique properties.

Oriented clay nanopaper from biobased components--mechanisms for superior fire protection properties.

PubMed

Carosio, F; Kochumalayil, J; Cuttica, F; Camino, G; Berglund, L

2015-03-18

The toxicity of the most efficient fire retardant additives is a major problem for polymeric materials. Cellulose nanofiber (CNF)/clay nanocomposites, with unique brick-and-mortar structure and prepared by simple filtration, are characterized from the morphological point of view by scanning electron microscopy and X-ray diffraction. These nanocomposites have superior fire protection properties to other clay nanocomposites and fiber composites. The corresponding mechanisms are evaluated in terms of flammability (reaction to a flame) and cone calorimetry (exposure to heat flux). These two tests provide a wide spectrum characterization of fire protection properties in CNF/montmorrilonite (MTM) materials. The morphology of the collected residues after flammability testing is investigated. In addition, thermal and thermo-oxidative stability are evaluated by thermogravimetric analyses performed in inert (nitrogen) and oxidative (air) atmospheres. Physical and chemical mechanisms are identified and related to the unique nanostructure and its low thermal conductivity, high gas barrier properties and CNF/MTM interactions for char formation.

Low-dimensional carbon and MXene-based electrochemical capacitor electrodes.

PubMed

Yoon, Yeoheung; Lee, Keunsik; Lee, Hyoyoung

2016-04-29

Due to their unique structure and outstanding intrinsic physical properties such as extraordinarily high electrical conductivity, large surface area, and various chemical functionalities, low-dimension-based materials exhibit great potential for application in electrochemical capacitors (ECs). The electrical properties of electrochemical capacitors are determined by the electrode materials. Because energy charge storage is a surface process, the surface properties of the electrode materials greatly influence the electrochemical performance of the cell. Recently, graphene, a single layer of sp(2)-bonded carbon atoms arrayed into two-dimensional carbon nanomaterial, has attracted wide interest as an electrode material for electrochemical capacitor applications due to its unique properties, including a high electrical conductivity and large surface area. Several low-dimensional materials with large surface areas and high conductivity such as onion-like carbons (OLCs), carbide-derived carbons (CDCs), carbon nanotubes (CNTs), graphene, metal hydroxide, transition metal dichalcogenides (TMDs), and most recently MXene, have been developed for electrochemical capacitors. Therefore, it is useful to understand the current issues of low-dimensional materials and their device applications.

Shape memory alloys: metallurgy, biocompatibility, and biomechanics for neurosurgical applications.

PubMed

Hoh, Daniel J; Hoh, Brian L; Amar, Arun P; Wang, Michael Y

2009-05-01

SHAPE MEMORY ALLOYS possess distinct dynamic properties with particular applications in neurosurgery. Because of their unique physical characteristics, these materials are finding increasing application where resiliency, conformation, and actuation are needed. Nitinol, the most frequently manufactured shape memory alloy, responds to thermal and mechanical stimuli with remarkable mechanical properties such as shape memory effect, super-elasticity, and high damping capacity. Nitinol has found particular use in the biomedical community because of its excellent fatigue resistance and biocompatibility, with special interest in neurosurgical applications. The properties of nitinol and its diffusionless phase transformations contribute to these unique mechanical capabilities. The features of nitinol, particularly its shape memory effect, super-elasticity, damping capacity, as well as its biocompatibility and biomechanics are discussed herein. Current and future applications of nitinol and other shape memory alloys in endovascular, spinal, and minimally invasive neurosurgery are introduced. An understanding of the metallurgic properties of nitinol provides a foundation for further exploration of its use in neurosurgical implant design.

Recent Advances in Nanocomposite Materials of Graphene Derivatives with Polysaccharides

PubMed Central

Terzopoulou, Zoi; Kyzas, George Z.; Bikiaris, Dimitrios N.

2015-01-01

This review article presents the recent advances in syntheses and applications of nanocomposites consisting of graphene derivatives with various polysaccharides. Graphene has recently attracted much interest in the materials field due to its unique 2D structure and outstanding properties. To follow, the physical and mechanical properties of graphene are then introduced. However it was observed that the synthesis of graphene-based nanocomposites had become one of the most important research frontiers in the application of graphene. Therefore, this review also summarizes the recent advances in the synthesis of graphene nanocomposites with polysaccharides, which are abundant in nature and are easily synthesized bio-based polymers. Polysaccharides can be classified in various ways such as cellulose, chitosan, starch, and alginates, each group with unique and different properties. Alginates are considered to be ideal for the preparation of nanocomposites with graphene derivatives due to their environmental-friendly potential. The characteristics of such nanocomposites are discussed here and are compared with regard to their mechanical properties and their various applications. PMID:28787964

A cluster bootstrap for two-loop MHV amplitudes

DOE PAGES

Golden, John; Spradlin, Marcus

2015-02-02

We apply a bootstrap procedure to two-loop MHV amplitudes in planar N=4 super-Yang-Mills theory. We argue that the mathematically most complicated part (the Λ 2 B 2 coproduct component) of the n-particle amplitude is uniquely determined by a simple cluster algebra property together with a few physical constraints (dihedral symmetry, analytic structure, supersymmetry, and well-defined collinear limits). Finally, we present a concise, closed-form expression which manifests these properties for all n.

Properties of the patient administered questionnaires: new scales measuring physical and psychological symptoms of hip and knee disorders.

PubMed

Mancuso, Carol A; Ranawat, Amar S; Meftah, Morteza; Koob, Trevor W; Ranawat, Chitranjan S

2012-04-01

The Patient Administered Questionnaires (PAQ) incorporate physical and psychological symptoms into one scale and permit more comprehensive self-reports for hip and knee disorders. We tested the psychometric properties of the PAQ-Hip and PAQ-Knee. Correlations between baseline PAQ-Hip and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) were .39 to .72 (n = 102), .39 to .69 for score change (n = 68 post-total hip arthroplasty), and most κ values > .60 (n = 50). Correlations between baseline PAQ-Knee and WOMAC were .35 to .64 (n = 100), .62 to .79 for score change (n = 43 post-total knee arthroplasty), and most κ values >.60 (n = 51). For both scales, effect sizes were higher than for the WOMAC, and there was modest correlation between physical and psychological questions, indicating these concepts are not completely interchangeable. Thus, the PAQ scales have strong psychometric properties and are unique compared with existing scales by including physical and psychological symptoms. Copyright © 2012 Elsevier Inc. All rights reserved.

Integrated Vehicle Ground Vibration Testing in Support of Launch Vehicle Loads and Controls Analysis

NASA Technical Reports Server (NTRS)

Askins, Bruce R.; Davis, Susan R.; Salyer, Blaine H.; Tuma, Margaret L.

2008-01-01

All structural systems possess a basic set of physical characteristics unique to that system. These unique physical characteristics include items such as mass distribution and damping. When specified, they allow engineers to understand and predict how a structural system behaves under given loading conditions and different methods of control. These physical properties of launch vehicles may be predicted by analysis or measured by certain types of tests. Generally, these properties are predicted by analysis during the design phase of a launch vehicle and then verified by testing before the vehicle becomes operational. A ground vibration test (GVT) is intended to measure by test the fundamental dynamic characteristics of launch vehicles during various phases of flight. During the series of tests, properties such as natural frequencies, mode shapes, and transfer functions are measured directly. These data will then be used to calibrate loads and control systems analysis models for verifying analyses of the launch vehicle. NASA manned launch vehicles have undergone ground vibration testing leading to the development of successful launch vehicles. A GVT was not performed on the inaugural launch of the unmanned Delta III which was lost during launch. Subsequent analyses indicated had a GVT been performed, it would have identified instability issues avoiding loss of the vehicle. This discussion will address GVT planning, set-up, execution and analyses, for the Saturn and Shuttle programs, and will also focus on the current and on-going planning for the Ares I and V Integrated Vehicle Ground Vibration Test (IVGVT).

The origami of life

NASA Astrophysics Data System (ADS)

Lezon, Timothy R.; Banavar, Jayanth R.; Maritan, Amos

2006-01-01

All living organisms rely upon networks of molecular interactions to carry out their vital processes. In order for a molecular system to display the properties of life, its constituent molecules must themselves be endowed with several features: stability, specificity, self-organization, functionality, sensitivity, robustness, diversity and adaptability. We argue that these are the emergent properties of a unique phase of matter, and we demonstrate that proteins, the functional molecules of terrestrial life, are perfectly suited to this phase. We explore, through an understanding of this phase of matter, the physical principles that govern the operation of living matter. Our work has implications for the design of functionally useful nanoscale devices and the ultimate development of physically based artificial life.

2D nanomaterials assembled from sequence-defined molecules

DOE PAGES

Mu, Peng; Zhou, Guangwen; Chen, Chun-Long

2017-10-21

Two dimensional (2D) nanomaterials have attracted broad interest owing to their unique physical and chemical properties with potential applications in electronics, chemistry, biology, medicine and pharmaceutics. Due to the current limitations of traditional 2D nanomaterials (e.g., graphene and graphene oxide) in tuning surface chemistry and compositions, 2D nanomaterials assembled from sequence-defined molecules (e.g., DNAs, proteins, peptides and peptoids) have recently been developed. They represent an emerging class of 2D nanomaterials with attractive physical and chemical properties. Here, we summarize the recent progress in the synthesis and applications of this type of sequence-defined 2D nanomaterials. We also discuss the challenges andmore » opportunities in this new field.« less

2D nanomaterials assembled from sequence-defined molecules

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

Mu, Peng; Zhou, Guangwen; Chen, Chun-Long

Two dimensional (2D) nanomaterials have attracted broad interest owing to their unique physical and chemical properties with potential applications in electronics, chemistry, biology, medicine and pharmaceutics. Due to the current limitations of traditional 2D nanomaterials (e.g., graphene and graphene oxide) in tuning surface chemistry and compositions, 2D nanomaterials assembled from sequence-defined molecules (e.g., DNAs, proteins, peptides and peptoids) have recently been developed. They represent an emerging class of 2D nanomaterials with attractive physical and chemical properties. Here, we summarize the recent progress in the synthesis and applications of this type of sequence-defined 2D nanomaterials. We also discuss the challenges andmore » opportunities in this new field.« less

Hydraulophones: Acoustic musical instruments and expressive user interfaces

NASA Astrophysics Data System (ADS)

Janzen, Ryan E.

Fluid flow creates an expansive range of acoustic possibilities, particularly in the case of water, which has unique turbulence and vortex shedding properties as compared with the air of ordinary wind instruments. Sound from water flow is explained with reference to a new class of musical instruments, hydraulophones, in which oscillation originates directly from matter in its liquid state. Several hydraulophones which were realized in practical form are described. A unique user-interface consisting of a row of water jets is presented, in terms of its expressiveness, tactility, responsiveness to derivatives and integrals of displacement, and in terms of the direct physical interaction between a user and the physical process of sound production. Signal processing algorithms are introduced, which extract further information from turbulent water flow, for industrial applications as well as musical applications.

Exposure, Health and Ecological Effects Review of Engineered Nanoscale Cerium and Cerium Oxide Associated with its Use as a Fuel Additive

EPA Science Inventory

Advances of nanoscale science have produced nanomaterials with unique physical and chemical properties at commercial levels which are now incorporated into over 1000 products. Nanoscale cerium (di) oxide (CeO(2)) has recently gained a wide range of applications which includes coa...

Substantiation of International Nanomaterials Security Group Creation

NASA Astrophysics Data System (ADS)

Sosnov, A.; Sadovnikov, S.; Panfilov, S.; Magarshak, Yu.

Nanotechnology has achieved the status as one of the critical R&D area. Scientists use the unique properties of atomic and molecular assemblages built at the nanometer scale. The ability to manipulate the physical, chemical, and biological properties of molecules and particles affords to design agents with set up properties. But the technology allows creating not only useful agents. Possible accidental or deliberate creation of new nanoparticles (NPs) with dangerous properties is highly probable minor product of progress in the new area. The article briefly describes some pathways in development and implementation of NPs for medicinal and the similar purposes. Some of NPs can effective facilitate and mask transport of various agents in various environments. Possible creation of new dangerous NPs (e.g. conjugates based on combination of extensively use NPs and chemical, biological and radioactive agents) as well as creation of brand new NPs and nanodevices with unique properties needs creation of international multidiscipline community for security evaluation of nanomaterials and technologies. The community will forecast possible dangerous unexpectedness in the field of nanoscale materials and devices and suggests rational pathways for prevention of the threats.

Tailoring the Spectroscopic Properties of Semiconductor Nanowires via Surface-Plasmon-Based Optical Engineering

PubMed Central

2014-01-01

Semiconductor nanowires, due to their unique electronic, optical, and chemical properties, are firmly placed at the forefront of nanotechnology research. The rich physics of semiconductor nanowire optics arises due to the enhanced light–matter interactions at the nanoscale and coupling of optical modes to electronic resonances. Furthermore, confinement of light can be taken to new extremes via coupling to the surface plasmon modes of metal nanostructures integrated with nanowires, leading to interesting physical phenomena. This Perspective will examine how the optical properties of semiconductor nanowires can be altered via their integration with highly confined plasmonic nanocavities that have resulted in properties such as orders of magnitude faster and more efficient light emission and lasing. The use of plasmonic nanocavities for tailored optical absorption will also be discussed in order to understand and engineer fundamental optical properties of these hybrid systems along with their potential for novel applications, which may not be possible with purely dielectric cavities. PMID:25396030

Cellulosic Nanomaterials in Food and Nutraceutical Applications: A Review.

PubMed

Khan, Avik; Wen, Yangbing; Huq, Tanzina; Ni, Yonghao

2018-01-10

Cellulosic nanomaterials (CNMs) are organic, green nanomaterials that are obtained from renewable sources and possess exceptional mechanical strength and biocompatibility. The associated unique physical and chemical properties have made these nanomaterials an intriguing prospect for various applications including the food and nutraceutical industry. From the immobilization of various bioactive agents and enzymes, emulsion stabilization, direct food additives, to the development of intelligent packaging systems or pathogen or pH detectors, the potential food related applications for CNMs are endless. Over the past decade, there have been several reviews published covering different aspects of cellulosic nanomaterials, such as processing-structure-property relationship, physical and chemical properties, rheology, extraction, nanocomposites, etc. In this critical review, we have discussed and provided a summary of the recent developments in the utilization of cellulosic nanomaterials in applications related to food and nutraceuticals.

Engineering the shape and structure of materials by fractal cut.

PubMed

Cho, Yigil; Shin, Joong-Ho; Costa, Avelino; Kim, Tae Ann; Kunin, Valentin; Li, Ju; Lee, Su Yeon; Yang, Shu; Han, Heung Nam; Choi, In-Suk; Srolovitz, David J

2014-12-09

In this paper we discuss the transformation of a sheet of material into a wide range of desired shapes and patterns by introducing a set of simple cuts in a multilevel hierarchy with different motifs. Each choice of hierarchical cut motif and cut level allows the material to expand into a unique structure with a unique set of properties. We can reverse-engineer the desired expanded geometries to find the requisite cut pattern to produce it without changing the physical properties of the initial material. The concept was experimentally realized and applied to create an electrode that expands to >800% the original area with only very minor stretching of the underlying material. The generality of our approach greatly expands the design space for materials so that they can be tuned for diverse applications.

Terapascal static pressure generation with ultrahigh yield strength nanodiamond.

PubMed

Dubrovinskaia, Natalia; Dubrovinsky, Leonid; Solopova, Natalia A; Abakumov, Artem; Turner, Stuart; Hanfland, Michael; Bykova, Elena; Bykov, Maxim; Prescher, Clemens; Prakapenka, Vitali B; Petitgirard, Sylvain; Chuvashova, Irina; Gasharova, Biliana; Mathis, Yves-Laurent; Ershov, Petr; Snigireva, Irina; Snigirev, Anatoly

2016-07-01

Studies of materials' properties at high and ultrahigh pressures lead to discoveries of unique physical and chemical phenomena and a deeper understanding of matter. In high-pressure research, an achievable static pressure limit is imposed by the strength of available strong materials and design of high-pressure devices. Using a high-pressure and high-temperature technique, we synthesized optically transparent microballs of bulk nanocrystalline diamond, which were found to have an exceptional yield strength (~460 GPa at a confining pressure of ~70 GPa) due to the unique microstructure of bulk nanocrystalline diamond. We used the nanodiamond balls in a double-stage diamond anvil cell high-pressure device that allowed us to generate static pressures beyond 1 TPa, as demonstrated by synchrotron x-ray diffraction. Outstanding mechanical properties (strain-dependent elasticity, very high hardness, and unprecedented yield strength) make the nanodiamond balls a unique device for ultrahigh static pressure generation. Structurally isotropic, homogeneous, and made of a low-Z material, they are promising in the field of x-ray optical applications.

Terapascal static pressure generation with ultrahigh yield strength nanodiamond

PubMed Central

Dubrovinskaia, Natalia; Dubrovinsky, Leonid; Solopova, Natalia A.; Abakumov, Artem; Turner, Stuart; Hanfland, Michael; Bykova, Elena; Bykov, Maxim; Prescher, Clemens; Prakapenka, Vitali B.; Petitgirard, Sylvain; Chuvashova, Irina; Gasharova, Biliana; Mathis, Yves-Laurent; Ershov, Petr; Snigireva, Irina; Snigirev, Anatoly

2016-01-01

Studies of materials’ properties at high and ultrahigh pressures lead to discoveries of unique physical and chemical phenomena and a deeper understanding of matter. In high-pressure research, an achievable static pressure limit is imposed by the strength of available strong materials and design of high-pressure devices. Using a high-pressure and high-temperature technique, we synthesized optically transparent microballs of bulk nanocrystalline diamond, which were found to have an exceptional yield strength (~460 GPa at a confining pressure of ~70 GPa) due to the unique microstructure of bulk nanocrystalline diamond. We used the nanodiamond balls in a double-stage diamond anvil cell high-pressure device that allowed us to generate static pressures beyond 1 TPa, as demonstrated by synchrotron x-ray diffraction. Outstanding mechanical properties (strain-dependent elasticity, very high hardness, and unprecedented yield strength) make the nanodiamond balls a unique device for ultrahigh static pressure generation. Structurally isotropic, homogeneous, and made of a low-Z material, they are promising in the field of x-ray optical applications. PMID:27453944

The development of graphene-based devices for cell biology research

NASA Astrophysics Data System (ADS)

Yan, Zhi-Qin; Zhang, Wei

2014-06-01

Graphene has emerged as a new carbon nanoform with great potential in many applications due to its exceptional physical and chemical properties. Especially, graphene and its derivatives are also gaining a lot of interest in the biomedical field as new components for biosensors, tissue engineering, and drug delivery. This review presents unique properties of graphene, the bio-effects of graphene and its derivatives, especially their interactions with cells and the development of graphene-based biosensors and nanomedicines for cancer diagnosis and treatment.

Influence of trace elements on dental enamel properties: A review.

PubMed

Qamar, Zeeshan; Haji Abdul Rahim, Zubaidah Binti; Chew, Hooi Pin; Fatima, Tayyaba

2017-01-01

Dental enamel, an avascular, irreparable, outermost and protective layer of the human clinical crown has a potential to withstand the physico-chemical effects and forces. These properties are being regulated by a unique association among elements occurring in the crystallites setup of human dental enamel. Calcium and phosphate are the major components (hydroxyapatite) in addition to some trace elements which have a profound effect on enamel. The current review was planned to determine the aptitude of various trace elements to substitute and their influence on human dental enamel in terms of physical and chemical properties.

Fermi-LAT Gamma-Ray Bursts and Insights from Swift

NASA Technical Reports Server (NTRS)

Racusin, Judith L.

2010-01-01

A new revolution in Gamma-ray Burst (GRB) observations and theory has begun over the last two years since the launch of the Fermi Gamma-ray Space Telescope. The new window into high energy gamma-rays opened by the Fermi-Large Area Telescope (LAT) is providing insight into prompt emission mechanisms and possibly also afterglow physics. The LAT detected GRBs appear to be a new unique subset of extremely energetic and bright bursts compared to the large sample detected by Swift over the last 6 years. In this talk, I will discuss the context and recent discoveries from these LAT GRBs and the large database of broadband observations collected by the Swift X-ray Telescope (XRT) and UV/Optical Telescope (UVOT). Through comparisons between the GRBs detected by Swift-BAT, G8M, and LAT, we can learn about the unique characteristics, physical differences, and the relationships between each population. These population characteristics provide insight into the different physical parameters that contribute to the diversity of observational GRB properties.

Exposure and Health Effects Review of Engineered Nanoscale Cerium and Cerium Dioxide Associated with its Use as a Fuel Additive - NOW IN PRINT IN THE JOURNAL

EPA Science Inventory

Advances of nanoscale science have produced nanomaterials with unique physical and chemical properties at commercial levels that are now incorporated into over 1000 products. Nanoscale cerium (di) oxide (Ce02) has recently gained a wide range of applications which includes coatin...

Determining the Energetics of the Hydrogen Bond through FTIR: A Hands-On Physical Chemistry Lab Experiment

ERIC Educational Resources Information Center

Guerin, Abby C.; Riley, Kristi; Rupnik, Kresimir; Kuroda, Daniel G.

2016-01-01

Hydrogen bonds are very important chemical structures that are responsible for many unique and important properties of solvents, such as the solvation power of water. These distinctive features are directly related to the stabilization energy conferred by hydrogen bonds to the solvent. Thus, the characterization of hydrogen bond energetics has…

Flora and vegetation of the Saint David and Lewis Springs Cienegas, Cochise County, Arizona

Treesearch

Elizabeth Makings

2013-01-01

In the Sky Island region, cienegas are rare marshlands amidst arid surroundings where groundwater perennially intersects the surface. Their unique physical properties give rise to a characteristic plant community dominated by wetland graminoids. Evaporation usually causes the water to be alkaline, and vegetation around a cienega commonly includes halophytes and other...

Carbon nanotube biosensors

PubMed Central

Tîlmaciu, Carmen-Mihaela; Morris, May C.

2015-01-01

Nanomaterials possess unique features which make them particularly attractive for biosensing applications. In particular, carbon nanotubes (CNTs) can serve as scaffolds for immobilization of biomolecules at their surface, and combine several exceptional physical, chemical, electrical, and optical characteristics properties which make them one of the best suited materials for the transduction of signals associated with the recognition of analytes, metabolites, or disease biomarkers. Here we provide a comprehensive review on these carbon nanostructures, in which we describe their structural and physical properties, functionalization and cellular uptake, biocompatibility, and toxicity issues. We further review historical developments in the field of biosensors, and describe the different types of biosensors which have been developed over time, with specific focus on CNT-conjugates engineered for biosensing applications, and in particular detection of cancer biomarkers. PMID:26579509

Carbon Nanotube Biosensors

NASA Astrophysics Data System (ADS)

Tilmaciu, Carmen-Mihaela; Morris, May

2015-10-01

Nanomaterials possess unique features which make them particularly attractive for biosensing applications. In particular Carbon Nanotubes (CNTs) can serve as scaffolds for immobilization of biomolecules at their surface, and combine several exceptional physical, chemical, electrical and optical characteristics properties which make them one of the best suited materials for the transduction of signals associated with the recognition of analytes, metabolites or disease biomarkers. Here we provide a comprehensive review on these carbon nanostructures, in which we will describe their structural and physical properties, discuss functionalization and cellular uptake, biocompatibility and toxicity issues. We further review historical developments in the field of biosensors, and describe the different types of biosensors which have been developed over time, with specific focus on CNT-conjugates engineered for biosensing applications, and in particular detection of cancer biomarkers.

2D nanomaterials assembled from sequence-defined molecules

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

Mu, Peng; Zhou, Guangwen; Chen, Chun-Long

Two dimensional (2D) nanomaterials have attracted broad interest owing to their unique physical and chemical properties with potential applications in electronics, chemistry, biology, medicine and pharmaceutics. Due to the current limitations of traditional 2D nanomaterials (e.g., graphene and graphene oxide) in tuning surface chemistry and compositions, 2D nanomaterials assembled from sequence-defined molecules (e.g., DNAs, proteins, peptides and peptoids) have recently been developed. They represent an emerging class of 2D nanomaterials with attractive physical and chemical properties. In this mini-review, we summarize the recent progress in the synthesis and applications of this type of sequence-defined 2D nanomaterials. The challenges and opportunitiesmore » in this new field are also discussed.« less

Effects of different combinations of “Baoshiling” on soil physical and chemical properties of Huangguogan

NASA Astrophysics Data System (ADS)

Xu, Y. H.; Wang, Z. H.; Xiong, B.; Qiu, X.; Liao, L.; Shun, G. C.; Huang, S. J.; Dong, Z. X.; Liu, X. Y.; Xi, L. J.

2017-08-01

The research is done on the Huangguogan (unique citrus breed in Sichuan, China). The experiment setted 27 groups of “Baoshiling” (self-study compound fertilizer) fertilization treatment to explore the “Baoshiling” different combinations on soil physical and chemical properties of Huangguogan. The results showed that all the combinations had improved the soil of Huangguogan orchard. The combination of A3B2C2 had the best effect. The best Fertilization management measures was “Baoshiling” bud flowering fertilizer 2kg, stable fruit fertilizer 2kg, strong fruit fertilizer 2kg. It could reduce the pH of soil and the bulk density of soil, increase the available nitrogen, available phosphorus, available potassium and urease activity.

Coronal magnetohydrodynamic waves and oscillations: observations and quests.

PubMed

Aschwanden, Markus J

2006-02-15

Coronal seismology, a new field of solar physics that emerged over the last 5 years, provides unique information on basic physical properties of the solar corona. The inhomogeneous coronal plasma supports a variety of magnetohydrodynamics (MHD) wave modes, which manifest themselves as standing waves (MHD oscillations) and propagating waves. Here, we briefly review the physical properties of observed MHD oscillations and waves, including fast kink modes, fast sausage modes, slow (acoustic) modes, torsional modes, their diagnostics of the coronal magnetic field, and their physical damping mechanisms. We discuss the excitation mechanisms of coronal MHD oscillations and waves: the origin of the exciter, exciter propagation, and excitation in magnetic reconnection outflow regions. Finally, we consider the role of coronal MHD oscillations and waves for coronal heating, the detectability of various MHD wave types, and we estimate the energies carried in the observed MHD waves and oscillations: Alfvénic MHD waves could potentially provide sufficient energy to sustain coronal heating, while acoustic MHD waves fall far short of the required coronal heating rates.

Physical property data from the ICDP-USGS Eyreville cores A and B, Chesapeake Bay impact structure, Virginia, USA, acquired using a multisensor core logger

USGS Publications Warehouse

Pierce, H.A.; Murray, J.B.

2009-01-01

The International Continental Scientific Drilling Program (ICDP) and the U.S. Geological Survey (USGS) drilled three core holes to a composite depth of 1766 m within the moat of the Chesapeake Bay impact structure. Core recovery rates from the drilling were high (??90%), but problems with core hole collapse limited the geophysical downhole logging to natural-gamma and temperature logs. To supplement the downhole logs, ??5% of the Chesapeake Bay impact structure cores was processed through the USGS GeoTek multisensor core logger (MSCL) located in Menlo Park, California. The measured physical properties included core thickness (cm), density (g cm-3), P-wave velocity (m s-1), P-wave amplitude (%), magnetic susceptibility (cgs), and resistivity (ohm-m). Fractional porosity was a secondary calculated property. The MSCL data-sampling interval for all core sections was 1 cm longitudinally. Photos of each MSCL sampled core section were imbedded with the physical property data for direct comparison. These data have been used in seismic, geologic, thermal history, magnetic, and gravity models of the Chesapeake Bay impact structure. Each physical property curve has a unique signature when viewed over the full depth of the Chesapeake Bay impact structure core holes. Variations in the measured properties reflect differences in pre-impact target-rock lithologies and spatial variations in impact-related deformation during late-stage crater collapse and ocean resurge. ?? 2009 The Geological Society of America.

Challenging the standard model by high-precision comparisons of the fundamental properties of protons and antiprotons

NASA Astrophysics Data System (ADS)

Ulmer, S.; Mooser, A.; Nagahama, H.; Sellner, S.; Smorra, C.

2018-03-01

The BASE collaboration investigates the fundamental properties of protons and antiprotons, such as charge-to-mass ratios and magnetic moments, using advanced cryogenic Penning trap systems. In recent years, we performed the most precise measurement of the magnetic moments of both the proton and the antiproton, and conducted the most precise comparison of the proton-to-antiproton charge-to-mass ratio. In addition, we have set the most stringent constraint on directly measured antiproton lifetime, based on a unique reservoir trap technique. Our matter/antimatter comparison experiments provide stringent tests of the fundamental charge-parity-time invariance, which is one of the fundamental symmetries of the standard model of particle physics. This article reviews the recent achievements of BASE and gives an outlook to our physics programme in the ELENA era. This article is part of the Theo Murphy meeting issue `Antiproton physics in the ELENA era'.

Electrical Control of Structural and Physical Properties via Strong Spin-Orbit Interactions in Sr2IrO4

NASA Astrophysics Data System (ADS)

Cao, G.; Terzic, J.; Zhao, H. D.; Zheng, H.; De Long, L. E.; Riseborough, Peter S.

2018-01-01

Electrical control of structural and physical properties is a long-sought, but elusive goal of contemporary science and technology. We demonstrate that a combination of strong spin-orbit interactions (SOI) and a canted antiferromagnetic Mott state is sufficient to attain that goal. The antiferromagnetic insulator Sr2IrO4 provides a model system in which strong SOI lock canted Ir magnetic moments to IrO6 octahedra, causing them to rigidly rotate together. A novel coupling between an applied electrical current and the canting angle reduces the Néel temperature and drives a large, nonlinear lattice expansion that closely tracks the magnetization, increases the electron mobility, and precipitates a unique resistive switching effect. Our observations open new avenues for understanding fundamental physics driven by strong SOI in condensed matter, and provide a new paradigm for functional materials and devices.

Challenging the standard model by high-precision comparisons of the fundamental properties of protons and antiprotons.

PubMed

Ulmer, S; Mooser, A; Nagahama, H; Sellner, S; Smorra, C

2018-03-28

The BASE collaboration investigates the fundamental properties of protons and antiprotons, such as charge-to-mass ratios and magnetic moments, using advanced cryogenic Penning trap systems. In recent years, we performed the most precise measurement of the magnetic moments of both the proton and the antiproton, and conducted the most precise comparison of the proton-to-antiproton charge-to-mass ratio. In addition, we have set the most stringent constraint on directly measured antiproton lifetime, based on a unique reservoir trap technique. Our matter/antimatter comparison experiments provide stringent tests of the fundamental charge-parity-time invariance, which is one of the fundamental symmetries of the standard model of particle physics. This article reviews the recent achievements of BASE and gives an outlook to our physics programme in the ELENA era.This article is part of the Theo Murphy meeting issue 'Antiproton physics in the ELENA era'. © 2018 The Authors.

Expanding frontiers in materials chemistry and physics with multiple anions.

PubMed

Kageyama, Hiroshi; Hayashi, Katsuro; Maeda, Kazuhiko; Attfield, J Paul; Hiroi, Zenji; Rondinelli, James M; Poeppelmeier, Kenneth R

2018-02-22

During the last century, inorganic oxide compounds laid foundations for materials synthesis, characterization, and technology translation by adding new functions into devices previously dominated by main-group element semiconductor compounds. Today, compounds with multiple anions beyond the single-oxide ion, such as oxyhalides and oxyhydrides, offer a new materials platform from which superior functionality may arise. Here we review the recent progress, status, and future prospects and challenges facing the development and deployment of mixed-anion compounds, focusing mainly on oxide-derived materials. We devote attention to the crucial roles that multiple anions play during synthesis, characterization, and in the physical properties of these materials. We discuss the opportunities enabled by recent advances in synthetic approaches for design of both local and overall structure, state-of-the-art characterization techniques to distinguish unique structural and chemical states, and chemical/physical properties emerging from the synergy of multiple anions for catalysis, energy conversion, and electronic materials.

Challenging the standard model by high-precision comparisons of the fundamental properties of protons and antiprotons

PubMed Central

Mooser, A.; Nagahama, H.; Sellner, S.; Smorra, C.

2018-01-01

The BASE collaboration investigates the fundamental properties of protons and antiprotons, such as charge-to-mass ratios and magnetic moments, using advanced cryogenic Penning trap systems. In recent years, we performed the most precise measurement of the magnetic moments of both the proton and the antiproton, and conducted the most precise comparison of the proton-to-antiproton charge-to-mass ratio. In addition, we have set the most stringent constraint on directly measured antiproton lifetime, based on a unique reservoir trap technique. Our matter/antimatter comparison experiments provide stringent tests of the fundamental charge–parity–time invariance, which is one of the fundamental symmetries of the standard model of particle physics. This article reviews the recent achievements of BASE and gives an outlook to our physics programme in the ELENA era. This article is part of the Theo Murphy meeting issue ‘Antiproton physics in the ELENA era’. PMID:29459414

Defect Chemistry and Plasmon Physics of Colloidal Metal Oxide Nanocrystals.

PubMed

Lounis, Sebastien D; Runnerstrom, Evan L; Llordés, Anna; Milliron, Delia J

2014-05-01

Plasmonic nanocrystals of highly doped metal oxides have seen rapid development in the past decade and represent a class of materials with unique optoelectronic properties. In this Perspective, we discuss doping mechanisms in metal oxides and the accompanying physics of free carrier scattering, both of which have implications in determining the properties of localized surface plasmon resonances (LSPRs) in these nanocrystals. The balance between activation and compensation of dopants limits the free carrier concentration of the most common metal oxides, placing a ceiling on the LSPR frequency. Furthermore, because of ionized impurity scattering of the oscillating plasma by dopant ions, scattering must be treated in a fundamentally different way in semiconductor metal oxide materials when compared with conventional metals. Though these effects are well-understood in bulk metal oxides, further study is needed to understand their manifestation in nanocrystals and corresponding impact on plasmonic properties, and to develop materials that surpass current limitations in free carrier concentration.

Characterization of Nanophase Materials

NASA Astrophysics Data System (ADS)

Wang, Zhong Lin

2000-01-01

Engineering of nanophase materials and devices is of vital interest in electronics, semiconductors and optics, catalysis, ceramics and magnetism. Research associated with nanoparticles has widely spread and diffused into every field of scientific research, forming a trend of nanocrystal engineered materials. The unique properties of nanophase materials are entirely determined by their atomic scale structures, particularly the structures of interfaces and surfaces. Development of nanotechnology involves several steps, of which characterization of nanoparticles is indespensable to understand the behavior and properties of nanoparticles, aiming at implementing nanotechnolgy, controlling their behavior and designing new nanomaterials systems with super performance. The book will focus on structural and property characterization of nanocrystals and their assemblies, with an emphasis on basic physical approach, detailed techniques, data interpretation and applications. Intended readers of this comprehensive reference work are advanced graduate students and researchers in the field, who are specialized in materials chemistry, materials physics and materials science.

High bulk modulus of ionic liquid and effects on performance of hydraulic system.

PubMed

Kambic, Milan; Kalb, Roland; Tasner, Tadej; Lovrec, Darko

2014-01-01

Over recent years ionic liquids have gained in importance, causing a growing number of scientists and engineers to investigate possible applications for these liquids because of their unique physical and chemical properties. Their outstanding advantages such as nonflammable liquid within a broad liquid range, high thermal, mechanical, and chemical stabilities, low solubility for gases, attractive tribological properties (lubrication), and very low compressibility, and so forth, make them more interesting for applications in mechanical engineering, offering great potential for new innovative processes, and also as a novel hydraulic fluid. This paper focuses on the outstanding compressibility properties of ionic liquid EMIM-EtSO4, a very important physical chemically property when IL is used as a hydraulic fluid. This very low compressibility (respectively, very high Bulk modulus), compared to the classical hydraulic mineral oils or the non-flammable HFDU type of hydraulic fluids, opens up new possibilities regarding its usage within hydraulic systems with increased dynamics, respectively, systems' dynamic responses.

The physics and chemistry of graphene-on-surfaces.

PubMed

Zhao, Guoke; Li, Xinming; Huang, Meirong; Zhen, Zhen; Zhong, Yujia; Chen, Qiao; Zhao, Xuanliang; He, Yijia; Hu, Ruirui; Yang, Tingting; Zhang, Rujing; Li, Changli; Kong, Jing; Xu, Jian-Bin; Ruoff, Rodney S; Zhu, Hongwei

2017-07-31

Graphene has demonstrated great potential in next-generation electronics due to its unique two-dimensional structure and properties including a zero-gap band structure, high electron mobility, and high electrical and thermal conductivity. The integration of atom-thick graphene into a device always involves its interaction with a supporting substrate by van der Waals forces and other intermolecular forces or even covalent bonding, and this is critical to its real applications. Graphene films on different surfaces are expected to exhibit significant differences in their properties, which lead to changes in their morphology, electronic structure, surface chemistry/physics, and surface/interface states. Therefore, a thorough understanding of the surface/interface properties is of great importance. In this review, we describe the major "graphene-on-surface" structures and examine the roles of their properties and related phenomena in governing the overall performance for specific applications including optoelectronics, surface catalysis, anti-friction and superlubricity, and coatings and composites. Finally, perspectives on the opportunities and challenges of graphene-on-surface systems are discussed.

Dislocation structures and electrical conduction properties of low angle tilt grain boundaries in LiNbO{sub 3}

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

Furushima, Yuho; Nakamura, Atsutomo, E-mail: nakamura@numse.nagoya-u.ac.jp; Toyoura, Kazuaki

Dislocations in crystalline materials constitute unique, atomic-scale, one-dimensional structure and have a potential to induce peculiar physical properties that are not found in the bulk. In this study, we fabricated LiNbO{sub 3} bicrystals with low angle tilt grain boundaries and investigated the relationship between the atomic structure of the boundary dislocations and their electrical conduction properties. Observations by using transmission electron microscopy revealed that dislocation structures at the (0001) low angle tilt grain boundaries depend on the tilt angle of the boundaries. Specifically, the characteristic dislocation structures with a large Burgers vector were formed in the boundary with the tiltmore » angle of 2°. It is noteworthy that only the grain boundary of 2° exhibits distinct electrical conductivity after reduction treatment, although LiNbO{sub 3} is originally insulating. This unique electrical conductivity is suggested to be due to the characteristic dislocation structures with a large Burgers vector.« less

Chapter 19: Catalysis by Metal Carbides and Nitrides

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

Schaidle, Joshua A; Nash, Connor P; Yung, Matthew M

Early transition metal carbides and nitrides (ETMCNs), materials in which carbon or nitrogen occupies interstitial sites within a parent metal lattice, possess unique physical and chemical properties that motivate their use as catalysts. Specifically, these materials possess multiple types of catalytic sites, including metallic, acidic, and basic sites, and as such, exhibit reactivities that differ from their parent metals. Moreover, their surfaces are dynamic under reaction conditions. This chapter reviews recent (since 2010) experimental and computational investigations into the catalytic properties of ETMCN materials for applications including biomass conversion, syngas and CO2 upgrading, petroleum and natural gas refining, and electrocatalyticmore » energy conversion, energy storage, and chemicals production, and attempts to link catalyst performance to active site identity/surface structure in order to elucidate the present level of understanding of structure-function relationships for these materials. The chapter concludes with a perspective on leveraging the unique properties of these materials to design and develop improved catalysts through a dedicated, multidisciplinary effort.« less

Rapid End-Group Modification of Polysaccharides for Biomaterial Applications in Regenerative Medicine.

PubMed

Bondalapati, Somasekhar; Ruvinov, Emil; Kryukov, Olga; Cohen, Smadar; Brik, Ashraf

2014-09-15

Polysaccharides have emerged as important functional materials because of their unique properties such as biocompatibility, biodegradability, and availability of reactive sites for chemical modifications to optimize their properties. The overwhelming majority of the methods to modify polysaccharides employ random chemical modifications, which often improve certain properties while compromising others. On the other hand, the employed methods for selective modifications often require excess of coupling partners, long reaction times and are limited in their scope and wide applicability. To circumvent these drawbacks, aniline-catalyzed oxime formation is developed for selective modification of a variety of polysaccharides through their reducing end. Notably, it is found that for efficient oxime formation, different conditions are required depending on the composition of the specific polysaccharide. It is also shown how our strategy can be applied to improve the physical and functional properties of alginate hydrogels, which are widely used in tissue engineering and regenerative medicine applications. While the randomly and selectively modified alginate exhibits similar viscoelastic properties, the latter forms significantly more stable hydrogel and superior cell adhesive and functional properties. Our results show that the developed conjugation reaction is robust and should open new opportunities for preparing polysaccharide-based functional materials with unique properties. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and Modification of Holey Graphene for Energy Storage

NASA Technical Reports Server (NTRS)

Lin, Yi; Kim, Jae-Woo; Connell, John W.

2015-01-01

Porous graphene materials have recently drawn significant interest for energy storage applications due to the effective use of the graphitic surface area provided by the pores. Holey graphene is a type of porous graphene with pores in the form of physical through thickness holes. This type of porous graphene provides a unique morphology that allows for effective transport of molecular species through the graphene plane. Therefore, as we recently demonstrated, holey graphene could be advantageous in the preparation of electrodes in supercapacitors with high volumetric performance.1 We have developed methodologies to scalably prepare holey graphene materials with or without the use of catalysts (Figure 1).1,2 In this presentation, we will discuss the choice of synthetic strategies and experimental conditions on the morphology and physical properties of holey graphene (Figure 2) and the effect on their electrochemical properties. We will also present the results on the further modification of holey graphene to study their physical and chemical properties, especially with regard to the stability and chemical reactivity of carbons located around the edges of the holes.

A Neural Model of Chromatic Induction in Uniform and Textured Images and Psychophysical Detection of Non-Opponent Chromatic Qualia

ERIC Educational Resources Information Center

Livitz, Gennady

2011-01-01

Color is a complex and rich perceptual phenomenon that relates physical properties of light to certain perceptual qualia associated with vision. Hering's opponent color theory, widely regarded as capturing the most fundamental aspects of color phenomenology, suggests that certain unique hues are mutually exclusive as components of a single color.…

Study of rare earth local moment magnetism and strongly correlated phenomena in various crystal structures

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

Kong, Tai

Benefiting from unique properties of 4f electrons, rare earth based compounds are known for offering a versatile playground for condensed matter physics research as well as industrial applications. This thesis focuses on three specific examples that further explore the rare earth local moment magnetism and strongly correlated phenomena in various crystal structures.

BoneSource hydroxyapatite cement: a novel biomaterial for craniofacial skeletal tissue engineering and reconstruction.

PubMed

Friedman, C D; Costantino, P D; Takagi, S; Chow, L C

1998-01-01

BoneSource-hydroxyapatite cement is a new self-setting calcium phosphate cement biomaterial. Its unique and innovative physical chemistry coupled with enhanced biocompatibility make it useful for craniofacial skeletal reconstruction. The general properties and clinical use guidelines are reviewed. The biomaterial and surgical applications offer insight into improved outcomes and potential new uses for hydroxyapatite cement systems.

Gold nanoprobes for theranostics

PubMed Central

Panchapakesan, Balaji; Book-Newell, Brittany; Sethu, Palaniappan; Rao, Madhusudhana; Irudayaraj, Joseph

2011-01-01

Gold nanoprobes have become attractive diagnostic and therapeutic agents in medicine and life sciences research owing to their reproducible synthesis with atomic level precision, unique physical and chemical properties, versatility of their morphologies, flexibility in functionalization, ease of targeting, efficiency in drug delivery and opportunities for multimodal therapy. This review highlights some of the recent advances and the potential for gold nanoprobes in theranostics. PMID:22122586

A nonlinear theory for elastic plates with application to characterizing paper properties

Treesearch

M. W. Johnson; Thomas J. Urbanik

1984-03-01

A theory of thin plates which is physically as well as kinematically nonlinear is, developed and used to characterize elastic material behavior for arbitrary stretching and bending deformations. It is developed from a few clearly defined assumptions and uses a unique treatment of strain energy. An effective strain concept is introduced to simplify the theory to a...

Biomedical Probes Based on Inorganic Nanoparticles for Electrochemical and Optical Spectroscopy Applications

PubMed Central

Yakoh, Abdulhadee; Pinyorospathum, Chanika; Siangproh, Weena; Chailapakul, Orawon

2015-01-01

Inorganic nanoparticles usually provide novel and unique physical properties as their size approaches nanometer scale dimensions. The unique physical and optical properties of nanoparticles may lead to applications in a variety of areas, including biomedical detection. Therefore, current research is now increasingly focused on the use of the high surface-to-volume ratios of nanoparticles to fabricate superb chemical- or biosensors for various detection applications. This article highlights various kinds of inorganic nanoparticles, including metal nanoparticles, magnetic nanoparticles, nanocomposites, and semiconductor nanoparticles that can be perceived as useful materials for biomedical probes and points to the outstanding results arising from their use in such probes. The progress in the use of inorganic nanoparticle-based electrochemical, colorimetric and spectrophotometric detection in recent applications, especially bioanalysis, and the main functions of inorganic nanoparticles in detection are reviewed. The article begins with a conceptual discussion of nanoparticles according to types, followed by numerous applications to analytes including biomolecules, disease markers, and pharmaceutical substances. Most of the references cited herein, dating from 2010 to 2015, generally mention one or more of the following characteristics: a low detection limit, good signal amplification and simultaneous detection capabilities. PMID:26343676

Are preferential flow paths perpetuated by microbial activity in the soil matrix? A review

NASA Astrophysics Data System (ADS)

Morales, Verónica L.; Parlange, J.-Yves; Steenhuis, Tammo S.

2010-10-01

SummaryRecently, the interactions between soil structure and microbes have been associated with water transport, retention and preferential or column flow development. Of particular significance is the potential impact of microbial extracellular polymeric substances (EPS) on soil porosity (i.e., hydraulic conductivity reduction or bioclogging) and of exudates from biota, including bacteria, fungi, roots and earthworms on the degree of soil water repellency. These structural and surface property changes create points of wetting instability, which under certain infiltrating conditions can often result in the formation of persistent preferential flow paths. Moreover, distinct differences in physical and chemical properties between regions of water flow (preferential flow paths) and no-flow (soil matrix) provide a unique set of environmental living conditions for adaptable microorganisms to exist. In this review, special consideration is given to: (1) the functional significance of microbial activity in the host porous medium in terms of feedback mechanisms instigated by irregular water availability and (2) the related physical and chemical conditions that force the organization and formation of unique microbial habitats in unsaturated soils that prompt and potentially perpetuate the formation of preferential flow paths in the vadose zone.

The golden age: gold nanoparticles for biomedicine†

PubMed Central

Dreaden, Erik C.; Alkilany, Alaaldin M.; Huang, Xiaohua; Murphy, Catherine J.; El-Sayed, Mostafa A.

2018-01-01

Gold nanoparticles have been used in biomedical applications since their first colloidal syntheses more than three centuries ago. However, over the past two decades, their beautiful colors and unique electronic properties have also attracted tremendous attention due to their historical applications in art and ancient medicine and current applications in enhanced optoelectronics and photovoltaics. In spite of their modest alchemical beginnings, gold nanoparticles exhibit physical properties that are truly different from both small molecules and bulk materials, as well as from other nanoscale particles. Their unique combination of properties is just beginning to be fully realized in range of medical diagnostic and therapeutic applications. This critical review will provide insights into the design, synthesis, functionalization, and applications of these artificial molecules in biomedicine and discuss their tailored interactions with biological systems to achieve improved patient health. Further, we provide a survey of the rapidly expanding body of literature on this topic and argue that gold nanotechnology-enabled biomedicine is not simply an act of ‘gilding the (nanomedicinal) lily’, but that a new ‘Golden Age’ of biomedical nanotechnology is truly upon us. Moving forward, the most challenging nanoscience ahead of us will be to find new chemical and physical methods of functionalizing gold nanoparticles with compounds that can promote efficient binding, clearance, and biocompatibility and to assess their safety to other biological systems and their long-term term effects on human health and reproduction (472 references). PMID:22109657

One‐Dimensional Ferroelectric Nanostructures: Synthesis, Properties, and Applications

PubMed Central

Liang, Longyue; Kang, Xueliang

2016-01-01

One‐dimensional (1D) ferroelectric nanostructures, such as nanowires, nanorods, nanotubes, nanobelts, and nanofibers, have been studied with increasing intensity in recent years. Because of their excellent ferroelectric, ferroelastic, pyroelectric, piezoelectric, inverse piezoelectric, ferroelectric‐photovoltaic (FE‐PV), and other unique physical properties, 1D ferroelectric nanostructures have been widely used in energy‐harvesting devices, nonvolatile random access memory applications, nanoelectromechanical systems, advanced sensors, FE‐PV devices, and photocatalysis mechanisms. This review summarizes the current state of 1D ferroelectric nanostructures and provides an overview of the synthesis methods, properties, and practical applications of 1D nanostructures. Finally, the prospects for future investigations are outlined. PMID:27812477

Processing and property evaluation of tungsten-based mixed oxides for photovoltaics and optoelectronics

NASA Astrophysics Data System (ADS)

Vargas, Mirella

Tungsten Oxide (WO3) films and low-dimensional structures have proven to be promising candidates in the fields of photonics and electronics. WO3 is a well-established n-type semiconductor characterized by unique electrochromic behavior, an ideal optical band gap that permits transparency over a wide spectral range, and high chemical integrity. The plethora of diverse properties endow WO3 to be highly effective in applications related to electrochromism, gas sensing, and deriving economical energy. Compared to the bulk films, a materials system involving WO3 and a related species (elements or metal oxides) offer the opportunity to tailor the electrochromic response, and an overall enhancement of the physio-chemical and optical properties. In the present case, WO3 and TiO2 composite films have been fabricated by reactive magnetron sputtering employing W/Ti alloy targets, and individual W and Ti targets for co-sputtering. Composite WO3-TiO2 films were fabricated with variable chemical composition and the effect of variable bulk chemistry on film structure, surface/interface chemistry and chemical valence state of the W and Ti cations was investigated in detail. The process-property relationships between composition and physical properties for the films deposited by using W/Ti alloy targets of variable Ti content are associated with decreases in the deposition rate of the WO3-TiO2 films due to the lower sputter yield of the strongly bonded TiO2 formed on the target surface. Additionally, for the co-sputtered films using variable tungsten power, the optical properties demonstrate unique optical modulation. The changes associated with the physical color of the films demonstrate the potential to tailor the optical behavior for the design and fabrication of multilayer photovoltaic and catalytic devices. The process-structure-property correlation derived in this work will provide a road-map to optimize and produce W-Ti-O thin films with desired properties for a given technological application.

Nuclear Medical Science Officers: Army Health Physicists Serving and Defending Their Country Around the Globe

NASA Astrophysics Data System (ADS)

Melanson, Mark; Bosley, William; Santiago, Jodi; Hamilton, Daniel

2010-02-01

Tracing their distinguished history back to the Manhattan Project that developed the world's first atomic bomb, the Nuclear Medical Science Officers are the Army's experts on radiation and its health effects. Serving around the globe, these commissioned Army officers serve as military health physicists that ensure the protection of Soldiers and those they defend against all sources of radiation, military and civilian. This poster will highlight the various roles and responsibilities that Nuclear Medical Science Officers fill in defense of the Nation. Areas where these officers serve include medical health physics, deployment health physics, homeland defense, emergency response, radiation dosimetry, radiation research and training, along with support to the Army's corporate radiation safety program and international collaborations. The poster will also share some of the unique military sources of radiation such as depleted uranium, which is used as an anti-armor munition and in armor plating because of its unique metallurgic properties. )

Bursting at the Seams: Rippled Monolayer Bismuth on NbSe 2

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

Fang, Alan; Adamo, Carolina; Jia, Shuang

Bismuth, one of the heaviest semimetals in nature, ignited the interest of the materials-physics community for its potential impact on topological quantum-material systems that utilize its strong spin-orbit coupling (SOC) and unique orbital hybridization. In particular, recent theoretical predictions of unique topological and superconducting properties of thin bismuth films and interfaces prompted intense research on the growth of sub- to a few monolayers of bismuth on different substrates. Similar to bulk rhombohedral bismuth, the initial growth of bismuth films on most substrates results in buckled bilayers that either grow in the (111) or (110) directions, with a lattice constant closemore » to that of bulk Bi. By contrast, in this paper we show a new growth pattern for bismuth monolayers on NbSe 2. We find that the initial growth of Bi can form a strongly bonded commensurate layer, resulting in a compressively strained two-dimensional triangular lattice. A unique pattern of 1D ripples and domain walls is observed. The single layer of bismuth also introduces strong marks on the electronic properties at the surface.« less

Guns and High Gas Output Devices Panel: Introduction

NASA Technical Reports Server (NTRS)

Simmons, Ronald L.; Kaste, Pamela J.

2000-01-01

A new panel known as the Guns and High Gas Output Panel was organized in 1999 under the auspices of the JANNAF Propellant and Characterization SubCommittee (PDCS). This is an introduction to our first meeting, purpose of the panel, and the scope of activities to be covered. The primary purpose of the panel is very simple: to provide a single focal point for interfacing Government Laboratories (Department of Defense and Department of Energy) and commercial industry researchers to share R&D activities and findings (i.e. facilitate the exchange of information) specifically aimed at gun-launched propulsion and high-gas output devices (gas generators and air bag inflators). Specific areas of interest included in the Panel's scope (and the Technical Data Base) are the following: (1) new propellant formulations and chemistry, (2) new ingredients, (3) ballistic effects of the new formulations and ingredients, (4) new processing methods unique to gun propellants, (5) thermochemistry of new ingredients, (6) unique physical and mechanical properties, (7) burning rates of new propellants and small scale closed bomb testing, (8) plasma effects on the propellant, and (9) unique safety and insensitive munitions properties.

Bursting at the Seams: Rippled Monolayer Bismuth on NbSe 2

DOE PAGES

Fang, Alan; Adamo, Carolina; Jia, Shuang; ...

2018-04-13

Bismuth, one of the heaviest semimetals in nature, ignited the interest of the materials-physics community for its potential impact on topological quantum-material systems that utilize its strong spin-orbit coupling (SOC) and unique orbital hybridization. In particular, recent theoretical predictions of unique topological and superconducting properties of thin bismuth films and interfaces prompted intense research on the growth of sub- to a few monolayers of bismuth on different substrates. Similar to bulk rhombohedral bismuth, the initial growth of bismuth films on most substrates results in buckled bilayers that either grow in the (111) or (110) directions, with a lattice constant closemore » to that of bulk Bi. By contrast, in this paper we show a new growth pattern for bismuth monolayers on NbSe 2. We find that the initial growth of Bi can form a strongly bonded commensurate layer, resulting in a compressively strained two-dimensional triangular lattice. A unique pattern of 1D ripples and domain walls is observed. The single layer of bismuth also introduces strong marks on the electronic properties at the surface.« less

Constraining the Physical Properties of Near-Earth Object 2009 BD

NASA Astrophysics Data System (ADS)

Mommert, M.; Hora, J. L.; Farnocchia, D.; Chesley, S. R.; Vokrouhlický, D.; Trilling, D. E.; Mueller, M.; Harris, A. W.; Smith, H. A.; Fazio, G. G.

2014-05-01

We report on Spitzer Space Telescope Infrared Array Camera observations of near-Earth object 2009 BD that were carried out in support of the NASA Asteroid Robotic Retrieval Mission concept. We did not detect 2009 BD in 25 hr of integration at 4.5 μm. Based on an upper-limit flux density determination from our data, we present a probabilistic derivation of the physical properties of this object. The analysis is based on the combination of a thermophysical model with an orbital model accounting for the non-gravitational forces acting upon the body. We find two physically possible solutions. The first solution shows 2009 BD as a 2.9 ± 0.3 m diameter rocky body (ρ = 2.9 ± 0.5 g cm-3) with an extremely high albedo of 0.85_{-0.10}^{+0.20} that is covered with regolith-like material, causing it to exhibit a low thermal inertia (\\Gamma =30_{-10}^{+20} SI units). The second solution suggests 2009 BD to be a 4 ± 1 m diameter asteroid with p_V=0.45_{-0.15}^{+0.35} that consists of a collection of individual bare rock slabs (Γ = 2000 ± 1000 SI units, \\rho = 1.7_{-0.4}^{+0.7} g cm-3). We are unable to rule out either solution based on physical reasoning. 2009 BD is the smallest asteroid for which physical properties have been constrained, in this case using an indirect method and based on a detection limit, providing unique information on the physical properties of objects in the size range smaller than 10 m.

On the Design of Forgiving Biometric Security Systems

NASA Astrophysics Data System (ADS)

Phan, Raphael C.-W.; Whitley, John N.; Parish, David J.

This work aims to highlight the fundamental issue surrounding biometric security systems: it’s all very nice until a biometric is forged, but what do we do after that? Granted, biometric systems are by physical nature supposedly much harder to forge than other factors of authentication since biometrics on a human body are by right unique to the particular human person. Yet it is also due to this physical nature that makes it much more catastrophic when a forgery does occur, because it implies that this uniqueness has been forged as well, threatening the human individuality; and since crime has by convention relied on identifying suspects by biometric characteristics, loss of this biometric uniqueness has devastating consequences on the freedom and basic human rights of the victimized individual. This uniqueness forgery implication also raises the motivation on the adversary to forge since a successful forgery leads to much more impersonation situations when biometric systems are used i.e. physical presence at crime scenes, identification and access to security systems and premises, access to financial accounts and hence the ability to use the victim’s finances. Depending on the gains, a desperate highly motivated adversary may even resort to directly obtaining the victim’s biometric parts by force e.g. severing the parts from the victim’s body; this poses a risk and threat not just to the individual’s uniqueness claim but also to personal safety and well being. One may then wonder if it is worth putting one’s assets, property and safety into the hands of biometrics based systems when the consequences of biometric forgery far outweigh the consequences of system compromises when no biometrics are used.

Terahertz magneto-optical spectroscopy of a two-dimensional hole gas

DOE PAGES

Kamaraju, N.; Pan, W.; Ekenberg, U.; ...

2015-01-21

Two-dimensional hole gases (2DHGs) have attracted recent attention for their unique quantum physics and potential applications in areas including spintronics and quantum computing. However, their properties remain relatively unexplored, motivating the use of different techniques to study them. We used terahertz magneto-optical spectroscopy to investigate the cyclotron resonance frequency in a high mobility 2DHG, revealing a nonlinear dependence on the applied magnetic field. This is also shown to be due to the complex non-parabolic valence band structure of the 2DHG, as verified by multiband Landau level calculations. We also find that impurity scattering dominates cyclotron resonance decay in the 2DHG,more » in contrast with the dominance of superradiant damping in two-dimensional electron gases. Furthermore, these results shed light on the properties of 2DHGs, motivating further studies of these unique 2D nanosystems.« less

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

Jiang, J.; Liu, Z. K.; Sun, Y.

Topological Weyl semimetal (TWS), a new state of quantum matter, has sparked enormous research interest recently. Possessing unique Weyl fermions in the bulk and Fermi arcs on the surface, TWSs offer a rare platform for realizing many exotic physical phenomena. TWSs can be classified into type-I that respect Lorentz symmetry and type-II that do not. Here, we directly visualize the electronic structure of MoTe 2, a recently proposed type-II TWS. Using angle-resolved photoemission spectroscopy (ARPES), we unravel the unique surface Fermi arcs, in good agreement with our ab initio calculations that have nontrivial topological nature. Our work not only leadsmore » to new understandings of the unusual properties discovered in this family of compounds, but also allows for the further exploration of exotic properties and practical applications of type-II TWSs, as well as the interplay between superconductivity (MoTe 2 was discovered to be superconducting recently) and their topological order.« less

Signature of Type-II Weyl Semimetal Phase in MoTe2

NASA Astrophysics Data System (ADS)

Jiang, Juan; Liu, Zhongkai; Yang, Haifeng; Yang, Lexian; Chen, Cheng; Peng, Han; Hwang, Chan-Cuk; Mo, Sung-Kwan; Chen, Yulin; ShanghaiTech University Collaboration; Oxford University Collaboration; Lawrence Berkeley National Lab Collaboration; Pohang University of Science; Technology Collaboration

Topological Weyl semimetal (TWS) is a new state of quantum matter, which has sparked enormous research interest recently. Possessing unique Weyl fermions in the bulk and Fermi arcs on the surface, TWSs offer a rare platform for realizing many exotic physical phenomena. Here, by using angle-resolved photoemission spectroscopy, we directly visualize the electronic structure of MoTe2, a recently proposed type-II TWS, which do not respect Lorentz symmetry compared with type-I TWS. Furthermore, we unravel the unique surface Fermi arcs, in good agreement with our ab-initio calculations, which have non-trivial topological nature. Our work not only leads to new understandings of the unusual properties discovered in this family of compounds, but also allows for the further exploration of exotic properties and practical applications of type-II TWSs, as well as the interplay between superconductivity and their topological order.

Signature of type-II Weyl semimetal phase in MoTe2

NASA Astrophysics Data System (ADS)

Jiang, J.; Liu, Z. K.; Sun, Y.; Yang, H. F.; Rajamathi, C. R.; Qi, Y. P.; Yang, L. X.; Chen, C.; Peng, H.; Hwang, C.-C.; Sun, S. Z.; Mo, S.-K.; Vobornik, I.; Fujii, J.; Parkin, S. S. P.; Felser, C.; Yan, B. H.; Chen, Y. L.

2017-01-01

Topological Weyl semimetal (TWS), a new state of quantum matter, has sparked enormous research interest recently. Possessing unique Weyl fermions in the bulk and Fermi arcs on the surface, TWSs offer a rare platform for realizing many exotic physical phenomena. TWSs can be classified into type-I that respect Lorentz symmetry and type-II that do not. Here, we directly visualize the electronic structure of MoTe2, a recently proposed type-II TWS. Using angle-resolved photoemission spectroscopy (ARPES), we unravel the unique surface Fermi arcs, in good agreement with our ab initio calculations that have nontrivial topological nature. Our work not only leads to new understandings of the unusual properties discovered in this family of compounds, but also allows for the further exploration of exotic properties and practical applications of type-II TWSs, as well as the interplay between superconductivity (MoTe2 was discovered to be superconducting recently) and their topological order.

Terahertz magneto-optical spectroscopy of a two-dimensional hole gas

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

Kamaraju, N., E-mail: nkamaraju@lanl.gov; Taylor, A. J.; Prasankumar, R. P., E-mail: rpprasan@lanl.gov

2015-01-19

Two-dimensional hole gases (2DHGs) have attracted recent attention for their unique quantum physics and potential applications in areas including spintronics and quantum computing. However, their properties remain relatively unexplored, motivating the use of different techniques to study them. We used terahertz magneto-optical spectroscopy to investigate the cyclotron resonance frequency in a high mobility 2DHG, revealing a nonlinear dependence on the applied magnetic field. This is shown to be due to the complex non-parabolic valence band structure of the 2DHG, as verified by multiband Landau level calculations. We also find that impurity scattering dominates cyclotron resonance decay in the 2DHG, inmore » contrast with the dominance of superradiant damping in two-dimensional electron gases. Our results shed light on the properties of 2DHGs, motivating further studies of these unique 2D nanosystems.« less

Low-Temperature Properties of Silver

PubMed Central

Smith, David R.; Fickett, F. R.

1995-01-01

Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability. PMID:29151733

Physical and chemical characterization of waste wood derived biochars.

PubMed

Yargicoglu, Erin N; Sadasivam, Bala Yamini; Reddy, Krishna R; Spokas, Kurt

2015-02-01

Biochar, a solid byproduct generated during waste biomass pyrolysis or gasification in the absence (or near-absence) of oxygen, has recently garnered interest for both agricultural and environmental management purposes owing to its unique physicochemical properties. Favorable properties of biochar include its high surface area and porosity, and ability to adsorb a variety of compounds, including nutrients, organic contaminants, and some gases. Physical and chemical properties of biochars are dictated by the feedstock and production processes (pyrolysis or gasification temperature, conversion technology and pre- and post-treatment processes, if any), which vary widely across commercially produced biochars. In this study, several commercially available biochars derived from waste wood are characterized for physical and chemical properties that can signify their relevant environmental applications. Parameters characterized include: physical properties (particle size distribution, specific gravity, density, porosity, surface area), hydraulic properties (hydraulic conductivity and water holding capacity), and chemical and electrochemical properties (organic matter and organic carbon contents, pH, oxidation-reduction potential and electrical conductivity, zeta potential, carbon, nitrogen and hydrogen (CHN) elemental composition, polycyclic aromatic hydrocarbons (PAHs), heavy metals, and leachable PAHs and heavy metals). A wide range of fixed carbon (0-47.8%), volatile matter (28-74.1%), and ash contents (1.5-65.7%) were observed among tested biochars. A high variability in surface area (0.1-155.1g/m(2)) and PAH and heavy metal contents of the solid phase among commercially available biochars was also observed (0.7-83 mg kg(-1)), underscoring the importance of pre-screening biochars prior to application. Production conditions appear to dictate PAH content--with the highest PAHs observed in biochar produced via fast pyrolysis and lowest among the gasification-produced biochars. Copyright © 2014 Elsevier Ltd. All rights reserved.

A Fundamental Study of Inorganic Clathrate and Other Open-Framework Materials

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

Nolas, George

Due to formidable synthetic challenges, many materials of scientific and technological interest are first obtained as microcrystalline powders. High purity, high yield processing techniques are often lacking and thus care must be taken in interpretation of the observed structural, chemical, and physical properties of powder or polycrystalline materials, which can be strongly influenced by extrinsic properties. Furthermore, the preparation of high-quality single crystals for many materials by traditional techniques can be especially challenging in cases where the elemental constituents have greatly differing melting points and/or vapor pressures, when the desired compound is thermodynamically metastable, or where growth with participation ofmore » the melt is generally not possible. New processing techniques are therefore imperative in order to investigate the intrinsic properties of these materials and elucidate their fundamental physical properties. Intermetallic clathrates constitute one such class of materials. The complex crystal structures of intermetallic clathrates are characterized by mainly group 14 host frameworks encapsulating guest-ions in polyhedral cages. The unique features of clathrate structures are intimately related to their physical properties, offering ideal systems for the study of structure-property relationships in crystalline solids. Moreover, intermetallic clathrates are being actively investigated due to their potential for application in thermoelectrics, photovoltaics and opto-electronics, superconductivity, and magnetocaloric technologies. We have developed different processing techniques in order to synthesize phase-pure high yield clathrates reproducibly, as well as grow single crystals for the first time. We also employed these techniques to synthesize new “open-framework” compounds. These advances in materials processing and crystal growth allowed for the investigation of the physical properties of a variety of different clathrate compositions for the first time.« less

Cp[prime]M(NO)R[sub 2]: 16-electron piano-stool molecules of molybdenum and tungsten

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

Legzdins, P.; Veltheer, J.E.

1993-02-01

A long-term goal of this research program is the development of organometallic nitrosyl complexes as specific reactants or selective catalysts for organic or organometallic transformations of practical significance. To attain this goal specifically with Cp[prime]M(NO)R[sub 2] system the authors developed new methods for their synthesis, established their characteristic physical and chemical properties, and are currently endeavoring to exploit those properties which are unique to the complexes. During our investigations, the authors have discovered that the Cp[prime]M(NO)R[sub 2] complexes react with a variety of small molecules, often in an unprecedented manner. The authors have also established several unique transformations that aremore » not exhibited by all members of this group of complexes. Indeed, the authors found that the chemical properties of these systems are often dependent on the metal, the nature of the R groups, and the type of Cp[prime] ligand. In this Account the authors summarize the synthesis, characterization, comparative reactivity, and distinctive chemical properties of the 16-electron Cp[prime]M(NO)R[sub 2] complexes known to date. 35 refs., 7 figs.« less

Signature properties of water: Their molecular electronic origins

PubMed Central

Jones, Andrew P.; Cipcigan, Flaviu S.; Crain, Jason; Martyna, Glenn J.

2015-01-01

Water challenges our fundamental understanding of emergent materials properties from a molecular perspective. It exhibits a uniquely rich phenomenology including dramatic variations in behavior over the wide temperature range of the liquid into water’s crystalline phases and amorphous states. We show that many-body responses arising from water’s electronic structure are essential mechanisms harnessed by the molecule to encode for the distinguishing features of its condensed states. We treat the complete set of these many-body responses nonperturbatively within a coarse-grained electronic structure derived exclusively from single-molecule properties. Such a “strong coupling” approach generates interaction terms of all symmetries to all orders, thereby enabling unique transferability to diverse local environments such as those encountered along the coexistence curve. The symmetries of local motifs that can potentially emerge are not known a priori. Consequently, electronic responses unfiltered by artificial truncation are then required to embody the terms that tip the balance to the correct set of structures. Therefore, our fully responsive molecular model produces, a simple, accurate, and intuitive picture of water’s complexity and its molecular origin, predicting water’s signature physical properties from ice, through liquid–vapor coexistence, to the critical point. PMID:25941394

Physics in ordered and disordered colloidal matter composed of poly(N-isopropylacrylamide) microgel particles.

PubMed

Yunker, Peter J; Chen, Ke; Gratale, Matthew D; Lohr, Matthew A; Still, Tim; Yodh, A G

2014-05-01

This review collects and describes experiments that employ colloidal suspensions to probe physics in ordered and disordered solids and related complex fluids. The unifying feature of this body of work is its clever usage of poly(N-isopropylacrylamide) (PNIPAM) microgel particles. These temperature-sensitive colloidal particles provide experimenters with a 'knob' for in situ control of particle size, particle interaction and particle packing fraction that, in turn, influence the structural and dynamical behavior of the complex fluids and solids. A brief summary of PNIPAM particle synthesis and properties is given, followed by a synopsis of current activity in the field. The latter discussion describes a variety of soft matter investigations including those that explore formation and melting of crystals and clusters, and those that probe structure, rearrangement and rheology of disordered (jammed/glassy) and partially ordered matter. The review, therefore, provides a snapshot of a broad range of physics phenomenology which benefits from the unique properties of responsive microgel particles.

Polymer-Based Nanocomposites: An Internship Program for Deaf and Hard of Hearing Students

NASA Astrophysics Data System (ADS)

Cebe, Peggy; Cherdack, Daniel; Seyhan Ince-Gunduz, B.; Guertin, Robert; Haas, Terry; Valluzzi, Regina

2007-03-01

We report on our summer internship program in Polymer-Based Nanocomposites, for deaf and hard of hearing undergraduates who engage in classroom and laboratory research work in polymer physics. The unique attributes of this program are its emphasis on: 1. Teamwork; 2. Performance of a start-to-finish research project; 3. Physics of materials approach; and 4. Diversity. Students of all disability levels have participated in this program, including students who neither hear nor voice. The classroom and laboratory components address the materials chemistry and physics of polymer-based nanocomposites, crystallization and melting of polymers, the interaction of X-rays and light with polymers, mechanical properties of polymers, and the connection between thermal processing, structure, and ultimate properties of polymers. A set of Best Practices is developed for accommodating deaf and hard of hearing students into the laboratory setting. The goal is to bring deaf and hard of hearing students into the larger scientific community as professionals, by providing positive scientific experiences at a formative time in their educational lives.

Dynamic Biological Functioning Important for Simulating and Stabilizing Ocean Biogeochemistry

NASA Astrophysics Data System (ADS)

Buchanan, P. J.; Matear, R. J.; Chase, Z.; Phipps, S. J.; Bindoff, N. L.

2018-04-01

The biogeochemistry of the ocean exerts a strong influence on the climate by modulating atmospheric greenhouse gases. In turn, ocean biogeochemistry depends on numerous physical and biological processes that change over space and time. Accurately simulating these processes is fundamental for accurately simulating the ocean's role within the climate. However, our simulation of these processes is often simplistic, despite a growing understanding of underlying biological dynamics. Here we explore how new parameterizations of biological processes affect simulated biogeochemical properties in a global ocean model. We combine 6 different physical realizations with 6 different biogeochemical parameterizations (36 unique ocean states). The biogeochemical parameterizations, all previously published, aim to more accurately represent the response of ocean biology to changing physical conditions. We make three major findings. First, oxygen, carbon, alkalinity, and phosphate fields are more sensitive to changes in the ocean's physical state. Only nitrate is more sensitive to changes in biological processes, and we suggest that assessment protocols for ocean biogeochemical models formally include the marine nitrogen cycle to assess their performance. Second, we show that dynamic variations in the production, remineralization, and stoichiometry of organic matter in response to changing environmental conditions benefit the simulation of ocean biogeochemistry. Third, dynamic biological functioning reduces the sensitivity of biogeochemical properties to physical change. Carbon and nitrogen inventories were 50% and 20% less sensitive to physical changes, respectively, in simulations that incorporated dynamic biological functioning. These results highlight the importance of a dynamic biology for ocean properties and climate.

New concepts in multidentate ligand chemistry: effects of multidentarity on catalytic and spectroscopic properties of ferrocenyl polyphosphines.

PubMed

Hierso, Jean-Cyrille; Smaliy, Radomyr; Amardeil, Régine; Meunier, Philippe

2007-11-01

This tutorial review devoted to ligand chemistry deals with the design and properties of ferrocenyl polyphosphines, an original class of multidentate ligands. The development of a varied library of ferrocenyl tetra-, tri- and diphosphine ligands is reviewed. The multidentate nature of these species has led to unique spectroscopic and catalytic properties, in which the spatial proximity of phosphorus atoms is crucial. Regarding their catalytic applications, the key issues of catalyst longevity and ultralow catalyst loadings are discussed. Another part is concerned with fundamental advances gained in physical chemistry for structure elucidation by the study of the intriguing "through-space" NMR spin-spin J couplings existing within several of these polyphosphines.

Characterizing ceramics and the interfacial adhesion to resin: I - The relationship of microstructure, composition, properties and fractography.

PubMed

Della Bona, Alvaro

2005-03-01

The appeal of ceramics as structural dental materials is based on their light weight, high hardness values, chemical inertness, and anticipated unique tribological characteristics. A major goal of current ceramic research and development is to produce tough, strong ceramics that can provide reliable performance in dental applications. Quantifying microstructural parameters is important to develop structure/property relationships. Quantitative microstructural analysis provides an association among the constitution, physical properties, and structural characteristics of materials. Structural reliability of dental ceramics is a major factor in the clinical success of ceramic restorations. Complex stress distributions are present in most practical conditions and strength data alone cannot be directly extrapolated to predict structural performance.

Soil Physicochemical and Biological Properties of Paddy-Upland Rotation: A Review

PubMed Central

Lv, Teng-Fei; Chen, Yong; Westby, Anthony P.; Ren, Wan-Jun

2014-01-01

Paddy-upland rotation is an unavoidable cropping system for Asia to meet the increasing demand for food. The reduction in grain yields has increased the research interest on the soil properties of rice-based cropping systems. Paddy-upland rotation fields are unique from other wetland or upland soils, because they are associated with frequent cycling between wetting and drying under anaerobic and aerobic conditions; such rotations affect the soil C and N cycles, make the chemical speciation and biological effectiveness of soil nutrient elements varied with seasons, increase the diversity of soil organisms, and make the soil physical properties more difficult to analyze. Consequently, maintaining or improving soil quality at a desirable level has become a complicated issue. Therefore, fully understanding the soil characteristics of paddy-upland rotation is necessary for the sustainable development of the system. In this paper, we offer helpful insight into the effect of rice-upland combinations on the soil chemical, physical, and biological properties, which could provide guidance for reasonable cultivation management measures and contribute to the improvement of soil quality and crop yield. PMID:24995366

Preparation of nanobiochar as magnetic solid acid catalyst by pyrolysis-carbonization from oil palm empty fruit bunches

NASA Astrophysics Data System (ADS)

Jenie, S. N. Aisyiyah; Kristiani, Anis; Kustomo, Simanungkalit, Sabar; Mansur, Dieni

2017-11-01

Nanomaterials based on carbon exhibits unique properties, both physical and chemical, that can be utilized in various application, including catalyst. These nanomaterials were prepared through pyrolysis-carbonization process of biomass, oil palm empty fruit bunches. The effect of carbonization temperature in range of 500°C-600°C were also studied. The magnetic nanobiochar samples, MBC, were sulfonated by using sulfuric acid to increase their properties as solid acid catalyst. Their chemical and physical properties were characterized by Surface Area Analyzer and Porositymeter, X-Ray Diffraction, Scanning Electron Microscopy, Fourier Transform Infra-Red. The magnetic biochar samples obtained from carbonization at 873 K, MBC02-SO3H, was proven to have higher surface area, crystallinity properties and surface chemical composition after sulfonation process, which were confirmed by the BET, XRD and FT-IR analysis. Moreover, sample MBC02-SO3H exhibit promising catalytic acitivity in a catalysed esterification reaction, producing an ester yield of 64%. The result from this work opens new opportunities for the development of magnetic heterogenous acid catalyst from biomass waste.

Glasses and Liquids Low on the Energy Landscape Prepared by Physical Vapor Deposition

NASA Astrophysics Data System (ADS)

Dalal, Shakeel; Fakhraai, Zahra; Ediger, Mark

2014-03-01

The lower portions of the potential energy landscape for glass-forming materials such as polymers and small molecules were historically inaccessible by experiments. Physical vapor deposition is uniquely able to prepare materials in this portion of the energy landscape, with the properties of the deposited material primarily modulated by the substrate temperature. Here we report on high-throughput experiments which utilize a temperature gradient stage to enable rapid screening of vapor-deposited organic glasses. Using ellipsometry, we characterize a 100 K range of substrate temperatures in a single experiment, allowing us to rapidly determine the density, kinetic stability, fictive temperature and molecular orientation of these glasses. Their properties fall into three temperature regimes. At substrate temperatures as low as 0.97Tg, we prepare materials which are equivalent to the supercooled liquid produced by cooling the melt. Below 0.9Tg (1.16TK) the properties of materials are kinetically controlled and highly tunable. At intermediate substrate temperatures we are able to produce materials whose bulk properties match those expected for the equilibrium supercooled liquid, down to 1.16TK, but are structurally anisotropic.

Screen-printed nanoparticles as anti-counterfeiting tags

NASA Astrophysics Data System (ADS)

Campos-Cuerva, Carlos; Zieba, Maciej; Sebastian, Victor; Martínez, Gema; Sese, Javier; Irusta, Silvia; Contamina, Vicente; Arruebo, Manuel; Santamaria, Jesus

2016-03-01

Metallic nanoparticles with different physical properties have been screen printed as authentication tags on different types of paper. Gold and silver nanoparticles show unique optical signatures, including sharp emission bandwidths and long lifetimes of the printed label, even under accelerated weathering conditions. Magnetic nanoparticles show distinct physical signals that depend on the size of the nanoparticle itself. They were also screen printed on different substrates and their magnetic signals read out using a magnetic pattern recognition sensor and a vibrating sample magnetometer. The novelty of our work lies in the demonstration that the combination of nanomaterials with optical and magnetic properties on the same printed support is possible, and the resulting combined signals can be used to obtain a user-configurable label, providing a high degree of security in anti-counterfeiting applications using simple commercially-available sensors.

Screen-printed nanoparticles as anti-counterfeiting tags.

PubMed

Campos-Cuerva, Carlos; Zieba, Maciej; Sebastian, Victor; Martínez, Gema; Sese, Javier; Irusta, Silvia; Contamina, Vicente; Arruebo, Manuel; Santamaria, Jesus

2016-03-04

Metallic nanoparticles with different physical properties have been screen printed as authentication tags on different types of paper. Gold and silver nanoparticles show unique optical signatures, including sharp emission bandwidths and long lifetimes of the printed label, even under accelerated weathering conditions. Magnetic nanoparticles show distinct physical signals that depend on the size of the nanoparticle itself. They were also screen printed on different substrates and their magnetic signals read out using a magnetic pattern recognition sensor and a vibrating sample magnetometer. The novelty of our work lies in the demonstration that the combination of nanomaterials with optical and magnetic properties on the same printed support is possible, and the resulting combined signals can be used to obtain a user-configurable label, providing a high degree of security in anti-counterfeiting applications using simple commercially-available sensors.

Fullerenes, carbon nanotubes, and graphene for molecular electronics.

PubMed

Pinzón, Julio R; Villalta-Cerdas, Adrián; Echegoyen, Luis

2012-01-01

With the constant growing complexity of electronic devices, the top-down approach used with silicon based technology is facing both technological and physical challenges. Carbon based nanomaterials are good candidates to be used in the construction of electronic circuitry using a bottom-up approach, because they have semiconductor properties and dimensions within the required physical limit to establish electrical connections. The unique electronic properties of fullerenes for example, have allowed the construction of molecular rectifiers and transistors that can operate with more than two logical states. Carbon nanotubes have shown their potential to be used in the construction of molecular wires and FET transistors that can operate in the THz frequency range. On the other hand, graphene is not only the most promising material for replacing ITO in the construction of transparent electrodes but it has also shown quantum Hall effect and conductance properties that depend on the edges or chemical doping. The purpose of this review is to present recent developments on the utilization carbon nanomaterials in molecular electronics.

Hydrogenation-controlled phase transition on two-dimensional transition metal dichalcogenides and their unique physical and catalytic properties.

PubMed

Qu, Yuanju; Pan, Hui; Kwok, Chi Tat

2016-09-30

Two-dimensional (2D) transition metal dichalcogenides (TMDs) have been widely used from nanodevices to energy harvesting/storage because of their tunable physical and chemical properties. In this work, we systematically investigate the effects of hydrogenation on the structural, electronic, magnetic, and catalytic properties of 33 TMDs based on first-principles calculations. We find that the stable phases of TMD monolayers can transit from 1T to 2H phase or vice versa upon the hydrogenation. We show that the hydrogenation can switch their magnetic and electronic states accompanying with the phase transition. The hydrogenation can tune the magnetic states of TMDs among non-, ferro, para-, and antiferro-magnetism and their electronic states among semiconductor, metal, and half-metal. We further show that, out of 33 TMD monolayers, 2H-TiS 2 has impressive catalytic ability comparable to Pt in hydrogen evolution reaction in a wide range of hydrogen coverages. Our findings would shed the light on the multi-functional applications of TMDs.

Carbon Nanotube-Reinforced Thermotropic Liquid Crystal Polymer Nanocomposites

PubMed Central

Kim, Jun Young

2009-01-01

This paper focuses on the fabrication via simple melt blending of thermotropic liquid crystal polyester (TLCP) nanocomposites reinforced with a very small quantity of modified carbon nanotube (CNT) and the unique effects of the modified CNT on the physical properties of the nanocomposites. The thermal, mechanical, and rheological properties of modified CNT-reinforced TLCP nanocomposites are highly dependent on the uniform dispersion of CNT and the interactions between the CNT and TLCP, which can be enhanced by chemical modification of the CNT, providing a design guide of CNT-reinforced TLCP nanocomposites with great potential for industrial uses.

Experimental insight into the magnetic and electrical properties of amorphous Ge1-xMnx

NASA Astrophysics Data System (ADS)

Conta, Gianluca; Amato, Giampiero; Coïsson, Marco; Tiberto, Paola

2017-12-01

We present a study of the electrical and magnetic properties of the amorphous Ge1-xMnx.DMS, with 2% ≤ x ≤ 17%, by means of SQUID magnetometry and low temperature DC measurements. The thin films were grown by physical vapour deposition at 50°C in ultrahigh vacuum. The DC electrical characterizations show that variable range hopping is the main mechanism of charge transport below room temperature. Magnetic characterization reveals that a unique and smooth magnetic transition is present in our samples, which can be attributed to ferromagnetic percolation of bound magnetic polarons.

Extraction of organic compounds with room temperature ionic liquids.

PubMed

Poole, Colin F; Poole, Salwa K

2010-04-16

Room temperature ionic liquids are novel solvents with a rather specific blend of physical and solution properties that makes them of interest for applications in separation science. They are good solvents for a wide range of compounds in which they behave as polar solvents. Their physical properties of note that distinguish them from conventional organic solvents are a negligible vapor pressure, high thermal stability, and relatively high viscosity. They can form biphasic systems with water or low polarity organic solvents and gases suitable for use in liquid-liquid and gas-liquid partition systems. An analysis of partition coefficients for varied compounds in these systems allows characterization of solvent selectivity using the solvation parameter model, which together with spectroscopic studies of solvent effects on probe substances, results in a detailed picture of solvent behavior. These studies indicate that the solution properties of ionic liquids are similar to those of polar organic solvents. Practical applications of ionic liquids in sample preparation include extractive distillation, aqueous biphasic systems, liquid-liquid extraction, liquid-phase microextraction, supported liquid membrane extraction, matrix solvents for headspace analysis, and micellar extraction. The specific advantages and limitations of ionic liquids in these studies is discussed with a view to defining future uses and the need not to neglect the identification of new room temperature ionic liquids with physical and solution properties tailored to the needs of specific sample preparation techniques. The defining feature of the special nature of ionic liquids is not their solution or physical properties viewed separately but their unique combinations when taken together compared with traditional organic solvents. Copyright 2009 Elsevier B.V. All rights reserved.

Understanding the physical properties of hybrid perovskites for photovoltaic applications

NASA Astrophysics Data System (ADS)

Huang, Jinsong; Yuan, Yongbo; Shao, Yuchuan; Yan, Yanfa

2017-07-01

New photovoltaic materials have been searched for in the past decades for clean and renewable solar energy conversion with an objective of reducing the levelized cost of electricity (that is, the unit price of electricity over the course of the device lifetime). An emerging family of semiconductor materials — organic-inorganic halide perovskites (OIHPs) — are the focus of the photovoltaic research community owing to their use of low cost, nature-abundant raw materials, low-temperature and scalable solution fabrication processes, and, in particular, the very high power conversion efficiencies that have been achieved within the short time of their development. In this Review, we summarize and critically assess the most recent advances in understanding the physical properties of both 3D and low-dimensional OIHPs that favour a small open-circuit voltage deficit and high power conversion efficiency. Several prominent topics in this field on the unique properties of OIHPs are surveyed, including defect physics, ferroelectricity, exciton dissociation processes, carrier recombination lifetime and photon recycling. The impact of ion migration on solar cell efficiency and stability are also critically analysed. Finally, we discuss the remaining challenges in the commercialization of OIHP photovoltaics.

Inverse Perovskites - A New Platform For 3D Dirac Electron Physics

NASA Astrophysics Data System (ADS)

Rost, A. W.; Kim, J.; Shota, S.; Hayama, K.; Abdolazimi, V.; Bruin, J. A. N.; Muehle, C.; Schnyder, A.; Yaresko, A. N.; Nuss, J.; Takagi, H.

3D Dirac semimetals show a wealth of phenomena including ultrahigh mobility, extreme transverse magnetoresistance and potential for negative longitudinal magnetoresistance. Furthermore, by introducing a gap these are often found to be topological crystalline insulators. Here, I will introduce our experiments on a new family of 3D Dirac materials - the inverse perovskites A3BO (A =Ca,Sr,Eu/B =Pb,Sn). These open up the possibility to chemically control the properties of Dirac electrons including (i) the anisotropy of the Dirac dispersion, (ii) role of spin orbit coupling, and (iii) magnetism. Our physical property measurements show all (Ca/Sr)3(Pb/Sn)O compounds host Dirac electrons at the Fermi energy with no other bands crossing EF. Quantum oscillations unveil small Fermi surfaces (frequencies <5 T) and light carriers (<0.02 me) only consistent with Dirac electrons. With the successful synthesis of Sr3Pb0.5Sn0.5O this group of materials therefore offers a unique chemical control over the physical properties of 3D Dirac electrons. Crucially, Eu3(Pb/Sn)O compounds allow for the introduction of magnetism. I will discuss the implications of this in particular with respect to surface states in these topological crystalline insulators.

Common Structure in Different Physical Properties: Electrical Conductivity and Surface Waves Phase Velocity

NASA Astrophysics Data System (ADS)

Mandolesi, E.; Jones, A. G.; Roux, E.; Lebedev, S.

2009-12-01

Recently different studies were undertaken on the correlation between diverse geophysical datasets. Magnetotelluric (MT) data are used to map the electrical conductivity structure behind the Earth, but one of the problems in MT method is the lack in resolution in mapping zones beneath a region of high conductivity. Joint inversion of different datasets in which a common structure is recognizable reduces non-uniqueness and may improve the quality of interpretation when different dataset are sensitive to different physical properties with an underlined common structure. A common structure is recognized if the change of physical properties occur at the same spatial locations. Common structure may be recognized in 1D inversion of seismic and MT datasets, and numerous authors show that also 2D common structure may drive to an improvement of inversion quality while dataset are jointly inverted. In this presentation a tool to constrain MT 2D inversion with phase velocity of surface wave seismic data (SW) is proposed and is being developed and tested on synthetic data. Results obtained suggest that a joint inversion scheme could be applied with success along a section profile for which data are compatible with a 2D MT model.

Faunal assemblages and multi-scale habitat patterns in headwater tributaries of the South Fork Trinity River - an unregulated river embedded within a multiple-use landscape

Treesearch

H. H. Jr. Welsh; J. J. G. R. Hodgson; J. M. Emlen Duda

2010-01-01

Headwaters can represent 80% of stream kilometers in a watershed, and they also have unique physical and biological properties that have only recently been recognized for their importance in sustaining healthy functioning stream networks and their ecological services. We sampled 60 headwater tributaries in the South Fork Trinity River, a 2,430 km2...

Use and application of gelatin as potential biodegradable packaging materials for food products.

PubMed

Nur Hanani, Z A; Roos, Y H; Kerry, J P

2014-11-01

The manufacture and potential application of biodegradable films for food application has gained increased interest as alternatives to conventional food packaging polymers due to the sustainable nature associated with their availability, broad and abundant source range, compostability, environmentally-friendly image, compatibility with foodstuffs and food application, etc. Gelatin is one such material and is a unique and popularly used hydrocolloid by the food industry today due to its inherent characteristics, thereby potentially offering a wide range of further and unique industrial applications. Gelatin from different sources have different physical and chemical properties as they contain different amino acid contents which are responsible for the varying characteristics observed upon utilization in food systems and when being utilized more specifically, in the manufacture of films. Packaging films can be successfully produced from all gelatin sources and the behaviour and characteristics of gelatin-based films can be altered through the incorporation of other food ingredients to produce composite films possessing enhanced physical and mechanical properties. This review will present the current situation with respect to gelatin usage as a packaging source material and the challenges that remain in order to move the manufacture of gelatin-based films nearer to commercial reality. Copyright © 2014 Elsevier B.V. All rights reserved.

Graphene with outstanding anti-irradiation capacity as multialkylated cyclopentanes additive toward space application

NASA Astrophysics Data System (ADS)

Fan, Xiaoqiang; Wang, Liping

2015-07-01

Multialkylated cyclopentanes (MACs), a class of synthetic hydrocarbon fluid have attracted intensive interest as possible space lubricants due to a series of unique physical and chemical properties. Here, we used graphene with high mechanical strength and chemical inertness as lubricant additive to explore its potential for space application. The effects of space irradiation on graphene and the tribological properties of graphene as lubricant additive were firstly investigated in detail under simulated space environment composed of high vacuum, high/low temperature and irradiation. Results demonstrate that graphene not only possesses outstanding anti-irradiation capacity but also significantly improves the space performance and tribological properties of MACs, which depends on the excellent physicochemical properties and high load-carrying ability of graphene as well as more effective separation of the sliding surfaces.

Graphene with outstanding anti-irradiation capacity as multialkylated cyclopentanes additive toward space application.

PubMed

Fan, Xiaoqiang; Wang, Liping

2015-07-30

Multialkylated cyclopentanes (MACs), a class of synthetic hydrocarbon fluid have attracted intensive interest as possible space lubricants due to a series of unique physical and chemical properties. Here, we used graphene with high mechanical strength and chemical inertness as lubricant additive to explore its potential for space application. The effects of space irradiation on graphene and the tribological properties of graphene as lubricant additive were firstly investigated in detail under simulated space environment composed of high vacuum, high/low temperature and irradiation. Results demonstrate that graphene not only possesses outstanding anti-irradiation capacity but also significantly improves the space performance and tribological properties of MACs, which depends on the excellent physicochemical properties and high load-carrying ability of graphene as well as more effective separation of the sliding surfaces.

Experimental Overview of Direct Photon Results in Heavy Ion Collisions

NASA Astrophysics Data System (ADS)

Novitzky, Norbert

2016-07-01

Direct photons are color blind probes and thus they provide unique opportunities to study the colored medium created in heavy ion collisions. There are many different sources of direct photons each probing different physics processes as the system evolves. In basic 2 → 2 processes the prompt photons from primary hard scatterings offer the most precise measurements of the outgoing parton energy in the opposite direction. In heavy ion collisions the created medium emits photons as thermal radiation, whose rate and anisotropies provide a unique prospective on the properties and evolution of the system. Recent results on direct photons from the LHC and RHIC experiments are briefly summarized in this paper.

On the non-uniqueness of the hydro-geomorphic responses in a zero-order catchment with respect to soil moisture

NASA Astrophysics Data System (ADS)

Kim, Jongho; Dwelle, M. Chase; Kampf, Stephanie K.; Fatichi, Simone; Ivanov, Valeriy Y.

2016-06-01

This study advances mechanistic interpretation of predictability challenges in hydro-geomorphology related to the role of soil moisture spatial variability. Using model formulations describing the physics of overland flow, variably saturated subsurface flow, and erosion and sediment transport, this study explores (1) why a basin with the same mean soil moisture can exhibit distinctly different spatial moisture distributions, (2) whether these varying distributions lead to non-unique hydro-geomorphic responses, and (3) what controls non-uniqueness in relation to the response type. Two sets of numerical experiments are carried out with two physically-based models, HYDRUS and tRIBS+VEGGIE+FEaST, and their outputs are analyzed with respect to pre-storm moisture state. The results demonstrate that distinct spatial moisture distributions for the same mean wetness arise because near-surface soil moisture dynamics exhibit different degrees of coupling with deeper-soil moisture and the process of subsurface drainage. The consequences of such variations are different depending on the type of hydrological response. Specifically, if the predominant runoff response is of infiltration excess type, the degree of non-uniqueness is related to the spatial distribution of near-surface moisture. If runoff is governed by subsurface stormflow, the extent of deep moisture contributing area and its "readiness to drain" determine the response characteristics. Because the processes of erosion and sediment transport superimpose additional controls over factors governing runoff generation and overland flow, non-uniqueness of the geomorphic response can be highly dampened or enhanced. The explanation is sediment composed by multi-size particles can alternate states of mobilization or surface shielding and the transient behavior is inherently intertwined with the availability of mobile particles. We conclude that complex nonlinear dynamics of hydro-geomorphic processes are inherent expressions of physical interactions. As complete knowledge of watershed properties, states, or forcings will always present the ultimate, if ever resolvable, challenge, deterministic predictability will remain handicapped. Coupling of uncertainty quantification methods and space-time physics-based approaches will need to evolve to facilitate mechanistic interpretations and informed practical applications.

Review of thermo-physical properties, wetting and heat transfer characteristics of nanofluids and their applicability in industrial quench heat treatment

PubMed Central

2011-01-01

The success of quenching process during industrial heat treatment mainly depends on the heat transfer characteristics of the quenching medium. In the case of quenching, the scope for redesigning the system or operational parameters for enhancing the heat transfer is very much limited and the emphasis should be on designing quench media with enhanced heat transfer characteristics. Recent studies on nanofluids have shown that these fluids offer improved wetting and heat transfer characteristics. Further water-based nanofluids are environment friendly as compared to mineral oil quench media. These potential advantages have led to the development of nanofluid-based quench media for heat treatment practices. In this article, thermo-physical properties, wetting and boiling heat transfer characteristics of nanofluids are reviewed and discussed. The unique thermal and heat transfer characteristics of nanofluids would be extremely useful for exploiting them as quench media for industrial heat treatment. PMID:21711877

Review of thermo-physical properties, wetting and heat transfer characteristics of nanofluids and their applicability in industrial quench heat treatment.

PubMed

Ramesh, Gopalan; Prabhu, Narayan Kotekar

2011-04-14

The success of quenching process during industrial heat treatment mainly depends on the heat transfer characteristics of the quenching medium. In the case of quenching, the scope for redesigning the system or operational parameters for enhancing the heat transfer is very much limited and the emphasis should be on designing quench media with enhanced heat transfer characteristics. Recent studies on nanofluids have shown that these fluids offer improved wetting and heat transfer characteristics. Further water-based nanofluids are environment friendly as compared to mineral oil quench media. These potential advantages have led to the development of nanofluid-based quench media for heat treatment practices. In this article, thermo-physical properties, wetting and boiling heat transfer characteristics of nanofluids are reviewed and discussed. The unique thermal and heat transfer characteristics of nanofluids would be extremely useful for exploiting them as quench media for industrial heat treatment.

Single-crystalline chromium silicide nanowires and their physical properties.

PubMed

Hsu, Han-Fu; Tsai, Ping-Chen; Lu, Kuo-Chang

2015-01-01

In this work, chromium disilicide nanowires were synthesized by chemical vapor deposition (CVD) processes on Si (100) substrates with hydrous chromium chloride (CrCl3 · 6H2O) as precursors. Processing parameters, including the temperature of Si (100) substrates and precursors, the gas flow rate, the heating time, and the different flow gas of reactions were varied and studied; additionally, the physical properties of the chromium disilicide nanowires were measured. It was found that single-crystal CrSi2 nanowires with a unique morphology were grown at 700°C, while single-crystal Cr5Si3 nanowires were grown at 750°C in reducing gas atmosphere. The crystal structure and growth direction were identified, and the growth mechanism was proposed as well. This study with magnetism, photoluminescence, and field emission measurements demonstrates that CrSi2 nanowires are attractive choices for future applications in magnetic storage, photovoltaic, and field emitters.

Modeling the directional reflectance from complete homogeneous vegetation canopies with various leaf-orientation distributions

NASA Technical Reports Server (NTRS)

Kimes, D. S.

1984-01-01

The directional-reflectance distributions of radiant flux from homogeneous vegetation canopies with greater than 90 percent ground cover are analyzed with a radiative-transfer model. The model assumes that the leaves consist of small finite planes with Lambertian properties. Four theoretical canopies with different leaf-orientation distributions were studied: erectophile, spherical, planophile, and heliotropic canopies. The directional-reflectance distributions from the model closely resemble reflectance distributions measured in the field. The physical scattering mechanisms operating in the model explain the variations observed in the reflectance distributions as a function of leaf-orientation distribution, solar zenith angle, and leaf transmittance and reflectance. The simulated reflectance distribution show unique characteristics for each canopy. The basic understanding of the physical scattering properties of the different canopy geometries gained in this study provide a basis for developing techniques to infer leaf-orientation distributions of vegetation canopies from directional remote-sensing measurements.

A review of polymer nanofibres by electrospinning and their application in oil-water separation for cleaning up marine oil spills.

PubMed

Sarbatly, Rosalam; Krishnaiah, Duduku; Kamin, Zykamilia

2016-05-15

The growths of oil and gas exploration and production activities have increased environmental problems, such as oil spillage and the resulting pollution. The study of the methods for cleaning up oil spills is a critical issue to protect the environment. Various techniques are available to contain oil spills, but they are typically time consuming, energy inefficient and create secondary pollution. The use of a sorbent, such as a nanofibre sorbent, is a technique for controlling oil spills because of its good physical and oil sorption properties. This review discusses about the application of nanofibre sorbent for oil removal from water and its current developments. With their unique physical and mechanical properties coupled with their very high surface area and small pore sizes, nanofibre sorbents are alternative materials for cleaning up oil spills. Copyright © 2016 Elsevier Ltd. All rights reserved.

Hydrodynamic Interactions in Active and Passive Matter

NASA Astrophysics Data System (ADS)

Krafnick, Ryan C.

Active matter is present at all biological length scales, from molecular apparatuses interior to cells, to swimming microscopic organisms, to birds, fish, and people. Its properties are varied and its applications diverse, but our understanding of the fundamental driving forces of systems with these constituents remains incomplete. This thesis examines active matter suspensions, exploring the role of hydrodynamic interactions on the unique and emergent properties therein. Both qualitative and quantitative impacts are considered, and care is taken in determining the physical origin of the results in question. It is found that fluid dynamical interactions are fundamentally, qualitatively important, and much of the properties of a system can be explained with an effective energy density defined via the fluid fields arising from the embedded self-propelling entities themselves.

Smart Functional Nanoenergetic Materials

DTIC Science & Technology

2012-08-01

Integrated Multiscale Organization of Energetic Materials Many biological and physical objects derive their unique properties through an...ve,  .  ancau , an   .  oss ,  g   nergy  u Nanocomposites obtained by DNA‐Directed Assembly, Adv. Functional Materials, 22,  323, 2012 Multiscale ...to any Multiscale Energetic Composites Fabricated on pSi Substrates • Si wafers (highly doped p-type) were photo lithographically patterned using

Quantum dot behavior in transition metal dichalcogenides nanostructures

NASA Astrophysics Data System (ADS)

Luo, Gang; Zhang, Zhuo-Zhi; Li, Hai-Ou; Song, Xiang-Xiang; Deng, Guang-Wei; Cao, Gang; Xiao, Ming; Guo, Guo-Ping

2017-08-01

Recently, transition metal dichalcogenides (TMDCs) semiconductors have been utilized for investigating quantum phenomena because of their unique band structures and novel electronic properties. In a quantum dot (QD), electrons are confined in all lateral dimensions, offering the possibility for detailed investigation and controlled manipulation of individual quantum systems. Beyond the definition of graphene QDs by opening an energy gap in nanoconstrictions, with the presence of a bandgap, gate-defined QDs can be achieved on TMDCs semiconductors. In this paper, we review the confinement and transport of QDs in TMDCs nanostructures. The fabrication techniques for demonstrating two-dimensional (2D) materials nanostructures such as field-effect transistors and QDs, mainly based on e-beam lithography and transfer assembly techniques are discussed. Subsequently, we focus on electron transport through TMDCs nanostructures and QDs. With steady improvement in nanoscale materials characterization and using graphene as a springboard, 2D materials offer a platform that allows creation of heterostructure QDs integrated with a variety of crystals, each of which has entirely unique physical properties.

Signature of type-II Weyl semimetal phase in MoTe 2

DOE PAGES

Jiang, J.; Liu, Z. K.; Sun, Y.; ...

2017-01-13

Topological Weyl semimetal (TWS), a new state of quantum matter, has sparked enormous research interest recently. Possessing unique Weyl fermions in the bulk and Fermi arcs on the surface, TWSs offer a rare platform for realizing many exotic physical phenomena. TWSs can be classified into type-I that respect Lorentz symmetry and type-II that do not. Here, we directly visualize the electronic structure of MoTe 2, a recently proposed type-II TWS. Using angle-resolved photoemission spectroscopy (ARPES), we unravel the unique surface Fermi arcs, in good agreement with our ab initio calculations that have nontrivial topological nature. Our work not only leadsmore » to new understandings of the unusual properties discovered in this family of compounds, but also allows for the further exploration of exotic properties and practical applications of type-II TWSs, as well as the interplay between superconductivity (MoTe 2 was discovered to be superconducting recently) and their topological order.« less

New materials graphyne, graphdiyne, graphone, and graphane: review of properties, synthesis, and application in nanotechnology.

PubMed

Peng, Qing; Dearden, Albert K; Crean, Jared; Han, Liang; Liu, Sheng; Wen, Xiaodong; De, Suvranu

2014-01-01

Plenty of new two-dimensional materials including graphyne, graphdiyne, graphone, and graphane have been proposed and unveiled after the discovery of the "wonder material" graphene. Graphyne and graphdiyne are two-dimensional carbon allotropes of graphene with honeycomb structures. Graphone and graphane are hydrogenated derivatives of graphene. The advanced and unique properties of these new materials make them highly promising for applications in next generation nanoelectronics. Here, we briefly review their properties, including structural, mechanical, physical, and chemical properties, as well as their synthesis and applications in nanotechnology. Graphyne is better than graphene in directional electronic properties and charge carriers. With a band gap and magnetism, graphone and graphane show important applications in nanoelectronics and spintronics. Because these materials are close to graphene and will play important roles in carbon-based electronic devices, they deserve further, careful, and thorough studies for nanotechnology applications.

New materials graphyne, graphdiyne, graphone, and graphane: review of properties, synthesis, and application in nanotechnology

PubMed Central

Peng, Qing; Dearden, Albert K; Crean, Jared; Han, Liang; Liu, Sheng; Wen, Xiaodong; De, Suvranu

2014-01-01

Plenty of new two-dimensional materials including graphyne, graphdiyne, graphone, and graphane have been proposed and unveiled after the discovery of the “wonder material” graphene. Graphyne and graphdiyne are two-dimensional carbon allotropes of graphene with honeycomb structures. Graphone and graphane are hydrogenated derivatives of graphene. The advanced and unique properties of these new materials make them highly promising for applications in next generation nanoelectronics. Here, we briefly review their properties, including structural, mechanical, physical, and chemical properties, as well as their synthesis and applications in nanotechnology. Graphyne is better than graphene in directional electronic properties and charge carriers. With a band gap and magnetism, graphone and graphane show important applications in nanoelectronics and spintronics. Because these materials are close to graphene and will play important roles in carbon-based electronic devices, they deserve further, careful, and thorough studies for nanotechnology applications. PMID:24808721

Nanotechnology: Opportunities and Challenges

NASA Technical Reports Server (NTRS)

Meyyappan, Meyya

2003-01-01

Nanotechnology seeks to exploit novel physical, chemical, biological, mechanical, electrical, and other properties, which arise primarily due to the nanoscale nature of certain materials. A key example is carbon nanotubes (CNTs) which exhibit unique electrical and extraordinary mechanical properties and offer remarkable potential for revolutionary applications in electronics devices, computing, and data storage technology, sensors, composites, nanoelectromechanical systems (NEMS), and as tip in scanning probe microscopy (SPM) for imaging and nanolithography. Thus the CNT synthesis, characterization, and applications touch upon all disciplines of science and engineering. This presentation will provide an overview and progress report on this and other major research candidates in Nanotechnology and address opportunities and challenges ahead.

Identification of extra neutral gauge bosons at the LHC using b and t quarks.

PubMed

Godfrey, Stephen; Martin, Travis A W

2008-10-10

New neutral gauge bosons (Z' 's) are predicted by many models of physics beyond the standard electroweak theory. It is possible that a Z' will be discovered by the Large Hadron Collider program. The next step would be to measure its properties to identify the underlying theory that gave rise to the Z'. Heavy quarks have the unique property that they can be identified in the final states. In this Letter we demonstrate that measuring Z' decays to b- and t-quark final states can act as an effective means of discriminating between models with extra gauge bosons.

Synthetic Design of Polysulfone Membranes: Morphological Effect on Property and Performance in Flow Batteries

NASA Astrophysics Data System (ADS)

Gindt, Brandon

This dissertation outlines a novel path towards improved understanding and function of proton exchange membranes (PEMs) for redox flow batteries, a large-scale battery storage device. This research uses synthetic methods and nanotechnology through two different approaches to prepare tailored polymer membranes: 1) Ion exchange membranes with enhanced chemical structures to promote membrane morphology on the nano-scale were prepared. Specifically, functional polysulfones (PSUs) were synthesized from different pre-sulfonated monomers. These PSUs have controlled placement and content of unique sulfonic acid moieties. PEMs were fabricated and characterized. The new PEMs showed desirable physical properties and performance in a vanadium redox flow battery (VRFB) cell. 2) Nanoporous PSU membranes were fabricated via post-hydrolysis of polylactide (PLA) from PLA-PSU-PLA triblock copolymer membranes. The controlled morphology and pore size of the resulting nanoporous membranes were evaluated by different microscopy and scattering techniques to understand structure-property relationships. Further, the resulting nanopore surface was chemically modified with sulfonic acid moieties. Membranes were analyzed and evaluated as separators for a VRFB. The chemically modified nanoporous PEMs exhibited unique behavior with respect to their ion conductivity when exposed to solutions of increasing acid concentration. In addition, the hierarchical micro-nanoporous membranes developed further showed promising structure and properties.

Prospects of Nanotechnology in Clinical Immunodiagnostics

PubMed Central

Ansari, Anees A.; Alhoshan, Mansour; Alsalhi, Mohamad S.; Aldwayyan, Abdullah S.

2010-01-01

Nanostructured materials are promising compounds that offer new opportunities as sensing platforms for the detection of biomolecules. Having micrometer-scale length and nanometer-scale diameters, nanomaterials can be manipulated with current nanofabrication methods, as well as self-assembly techniques, to fabricate nanoscale bio-sensing devices. Nanostructured materials possess extraordinary physical, mechanical, electrical, thermal and multifunctional properties. Such unique properties advocate their use as biomimetic membranes to immobilize and modify biomolecules on the surface of nanoparticles. Alignment, uniform dispersion, selective growth and diameter control are general parameters which play critical roles in the successful integration of nanostructures for the fabrication of bioelectronic sensing devices. In this review, we focus on different types and aspects of nanomaterials, including their synthesis, properties, conjugation with biomolecules and their application in the construction of immunosensing devices. Some key results from each cited article are summarized by relating the concept and mechanism behind each sensor, experimental conditions and the behavior of the sensor under different conditions, etc. The variety of nanomaterial-based bioelectronic devices exhibiting novel functions proves the unique properties of nanomaterials in such sensing devices, which will surely continue to expand in the future. Such nanomaterial based devices are expected to have a major impact in clinical immunodiagnostics, environmental monitoring, security surveillance and for ensuring food safety. PMID:22163566

Rational engineering of physicochemical properties of nanomaterials for biomedical applications with nanotoxicological perspectives.

PubMed

Navya, P N; Daima, Hemant Kumar

2016-01-01

Innovative engineered nanomaterials are at the leading edge of rapidly emerging fields of nanobiotechnology and nanomedicine. Meticulous synthesis, unique physicochemical properties, manifestation of chemical or biological moieties on the surface of materials make engineered nanostructures suitable for a variety of biomedical applications. Besides, tailored nanomaterials exhibit entirely novel therapeutic applications with better functionality, sensitivity, efficiency and specificity due to their customized unique physicochemical and surface properties. Additionally, such designer made nanomaterials has potential to generate series of interactions with various biological entities including DNA, proteins, membranes, cells and organelles at nano-bio interface. These nano-bio interactions are driven by colloidal forces and predominantly depend on the dynamic physicochemical and surface properties of nanomaterials. Nevertheless, recent development and atomic scale tailoring of various physical, chemical and surface properties of nanomaterials is promising to dictate their interaction in anticipated manner with biological entities for biomedical applications. As a result, rationally designed nanomaterials are in extensive demand for bio-molecular detection and diagnostics, therapeutics, drug and gene delivery, fluorescent labelling, tissue engineering, biochemical sensing and other pharmaceuticals applications. However, toxicity and risk associated with engineered nanomaterials is rather unclear or not well understood; which is gaining considerable attention and the field of nanotoxicology is evolving promptly. Therefore, this review explores current knowledge of articulate engineering of nanomaterials for biomedical applications with special attention on potential toxicological perspectives.

Rational engineering of physicochemical properties of nanomaterials for biomedical applications with nanotoxicological perspectives

NASA Astrophysics Data System (ADS)

Navya, P. N.; Daima, Hemant Kumar

2016-02-01

Innovative engineered nanomaterials are at the leading edge of rapidly emerging fields of nanobiotechnology and nanomedicine. Meticulous synthesis, unique physicochemical properties, manifestation of chemical or biological moieties on the surface of materials make engineered nanostructures suitable for a variety of biomedical applications. Besides, tailored nanomaterials exhibit entirely novel therapeutic applications with better functionality, sensitivity, efficiency and specificity due to their customized unique physicochemical and surface properties. Additionally, such designer made nanomaterials has potential to generate series of interactions with various biological entities including DNA, proteins, membranes, cells and organelles at nano-bio interface. These nano-bio interactions are driven by colloidal forces and predominantly depend on the dynamic physicochemical and surface properties of nanomaterials. Nevertheless, recent development and atomic scale tailoring of various physical, chemical and surface properties of nanomaterials is promising to dictate their interaction in anticipated manner with biological entities for biomedical applications. As a result, rationally designed nanomaterials are in extensive demand for bio-molecular detection and diagnostics, therapeutics, drug and gene delivery, fluorescent labelling, tissue engineering, biochemical sensing and other pharmaceuticals applications. However, toxicity and risk associated with engineered nanomaterials is rather unclear or not well understood; which is gaining considerable attention and the field of nanotoxicology is evolving promptly. Therefore, this review explores current knowledge of articulate engineering of nanomaterials for biomedical applications with special attention on potential toxicological perspectives.

Graphene with outstanding anti-irradiation capacity as multialkylated cyclopentanes additive toward space application

PubMed Central

Fan, Xiaoqiang; Wang, Liping

2015-01-01

Multialkylated cyclopentanes (MACs), a class of synthetic hydrocarbon fluid have attracted intensive interest as possible space lubricants due to a series of unique physical and chemical properties. Here, we used graphene with high mechanical strength and chemical inertness as lubricant additive to explore its potential for space application. The effects of space irradiation on graphene and the tribological properties of graphene as lubricant additive were firstly investigated in detail under simulated space environment composed of high vacuum, high/low temperature and irradiation. Results demonstrate that graphene not only possesses outstanding anti–irradiation capacity but also significantly improves the space performance and tribological properties of MACs, which depends on the excellent physicochemical properties and high load-carrying ability of graphene as well as more effective separation of the sliding surfaces. PMID:26224254

Biominerals- hierarchical nanocomposites: the example of bone

PubMed Central

Beniash, Elia

2010-01-01

Many organisms incorporate inorganic solids in their tissues to enhance their functional, primarily mechanical, properties. These mineralized tissues, also called biominerals, are unique organo-mineral nanocomposites, organized at several hierarchical levels, from nano- to macroscale. Unlike man made composite materials, which often are simple physical blends of their components, the organic and inorganic phases in biominerals interface at the molecular level. Although these tissues are made of relatively weak components at ambient conditions, their hierarchical structural organization and intimate interactions between different elements lead to superior mechanical properties. Understanding basic principles of formation, structure and functional properties of these tissues might lead to novel bioinspired strategies for material design and better treatments for diseases of the mineralized tissues. This review focuses on general principles of structural organization, formation and functional properties of biominerals on the example the bone tissues. PMID:20827739

Impact of ultrasonic assisted triangular lattice like arranged dispersion of nanoparticles on physical and mechanical properties of epoxy-TiO2 nanocomposites.

PubMed

Goyat, M S; Ghosh, P K

2018-04-01

Emerging ex-situ technique, ultrasonic dual mixing (UDM) offers unique and hitherto unapproachable opportunities to alter the physical and mechanical properties of polymer nanocomposites. In this study, triangular lattice-like arranged dispersion of TiO 2 nanoparticles (average size ∼ 48 nm) in the epoxy polymer has been attained via concurrent use of a probe ultra-sonicator and 4 blades pitched impeller which collectively named as UDM technique. The UDM processing of neat epoxy reveals the generation of triangular lattice-like arranged nanocavities with nanoscale inter-cavity spacing. The UDM processing of epoxy-TiO 2 nanocomposites reveals two unique features such as partial and complete entrapping of the nanoparticles by the nanocavities leading the arranged dispersion of particles in the epoxy matrix. Pristine TiO 2 nanoparticles were dispersed in the epoxy polymer at loading fractions of up to 20% by weight. The results display that the arranged dispersion of nanoparticles is very effective at enhancing the glass transition temperature (T g ) and tensile properties of the epoxy at loading fractions of 10 wt%. We quantify a direct relationship among three important parameters such as nanoparticle content, cluster size, and inter-particle spacing. Our results offer a novel understanding of these parameters on the T g and tensile properties of the epoxy nanocomposites. The tensile fracture surfaces revealed several toughening mechanisms such as particle pull-out, plastic void growth, crack deflection, crack bridging and plastic deformation. We show that a strong nanoparticle-matrix interface led to the enhanced mechanical properties due to leading toughening mechanisms such as crack deflection, plastic deformation and particle pull-out. We showed that the UDM has an inordinate prospective to alter the dispersion state of nanoparticles in viscous polymer matrices. Copyright © 2017 Elsevier B.V. All rights reserved.

Towards a physical classification of early-type galaxies. Profile of a key programme.

NASA Astrophysics Data System (ADS)

Bender, R.; Capaccioli, M.; Macchetto, F.; Nieto, J.-L.

1989-03-01

Hubble was the first who succeeded in classifying galaxies within a scheme of some physical meaning. Although it soon became clear that Hubble's tuning fork does not represent an evolutionary sequence, this essential diagram has proven to be a powerful tool especially for the understanding of late-type galaxies. On the other hand, the "early-type" sequence of elliptical (E) and SO galaxies is less satisfying, because it does not seem to reflect a unique sequence of physical properties. The SO class, although conceived to bridge the gap between disk- and disk-Iess galaxies, has often been abused to host ellipticals exhibiting peculiarities incompatible with their definition as structureless objects. For the elliptical galaxies themselves, "ellipticity" has been found to be essentially meaningless with regard to their angular momentum properties, and shows Iittle, if any, correlation with other global parameters. This fact became apparent after the first stellar kinematical measurements of luminous ellipticals (Bertola and Capaccioli 1975, IIlingworth 1977); E galaxies are not necessarily f1attened by rotation and may have anisotropie velocity dispersions (Binney 1978).

An Internship Program for Deaf and Hard of Hearing Students in Polymer-Based Nanocomposites

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

Cebe,P.; Cherdack, D.; Guertin, R.

2006-01-01

We report on our summer internship program in Polymer-Based Nanocomposites, for deaf and hard of hearing undergraduates who engage in classroom and laboratory research work in polymer physics. The unique attributes of this program are its emphasis on: 1. Teamwork; 2. Performance of a start-to-finish research project; 3. Physics of materials approach; and 4. Diversity. Students of all disability levels have participated in this program, including students who neither hear nor voice. The classroom and laboratory components address the materials chemistry and physics of polymer-based nanocomposites, crystallization and melting of polymers, the interaction of X-rays and light with polymers, mechanicalmore » properties of polymers, and the connection between thermal processing, structure, and ultimate properties of polymers. A set of Best Practices is developed for accommodating deaf and hard of hearing students into the laboratory setting. The goal is to bring deaf and hard of hearing students into the larger scientific community as professionals, by providing positive scientific experiences at a formative time in their educational lives.« less

Organic-Inorganic Perovskites: Structural Versatility for Functional Materials Design.

PubMed

Saparov, Bayrammurad; Mitzi, David B

2016-04-13

Although known since the late 19th century, organic-inorganic perovskites have recently received extraordinary research community attention because of their unique physical properties, which make them promising candidates for application in photovoltaic (PV) and related optoelectronic devices. This review will explore beyond the current focus on three-dimensional (3-D) lead(II) halide perovskites, to highlight the great chemical flexibility and outstanding potential of the broader class of 3-D and lower dimensional organic-based perovskite family for electronic, optical, and energy-based applications as well as fundamental research. The concept of a multifunctional organic-inorganic hybrid, in which the organic and inorganic structural components provide intentional, unique, and hopefully synergistic features to the compound, represents an important contemporary target.

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

Gürel, Hikmet Hakan, E-mail: hhakan.gurel@kocaeli.edu.tr; Salmankurt, Bahadır

Graphene as a 2D material has unique chemical and electronic properties. Because of its unique physical, chemical, and electronic properties, its interesting shape and size make it a promising nanomaterial in many biological applications. However, the lower water-solubility and the irreversible aggregation due to the strong π-π stacking hinder the wide application of graphene nanosheets in biomedical field. Thus, graphene oxide (GO), one derivative of graphene, has been used more frequently in the biological system owing to its relatively higher water solubility and biocompatibility. Recently, it has been demonstrated that nanomaterials with different functional groups on the surface can bemore » used to bind the drug molecules with high affinity. GO has different functional groups such as H, OH and O on its surface; it can be a potential candidate as a drug carrier. The interactions of biomolecules and graphene like structures are long-ranged and very weak. Development of new techniques is very desirable for design of bioelectronics sensors and devices. In this work, we present first-principles spin polarized calculations within density functional theory to calculate effects of charging on DNA/RNA nucleobases on graphene oxide. It is shown that how modify structural and electronic properties of nucleobases on graphene oxide by applied charging.« less

Ceramic composites: A review of toughening mechanisms and demonstration of micropillar compression for interface property extraction

DOE PAGES

Kabel, Joey; Hosemann, Peter; Zayachuk, Yevhen; ...

2018-01-24

We present that ceramic fiber–matrix composites (CFMCs) are exciting materials for engineering applications in extreme environments. By integrating ceramic fibers within a ceramic matrix, CFMCs allow an intrinsically brittle material to exhibit sufficient structural toughness for use in gas turbines and nuclear reactors. Chemical stability under high temperature and irradiation coupled with high specific strength make these materials unique and increasingly popular in extreme settings. This paper first offers a review of the importance and growing body of research on fiber–matrix interfaces as they relate to composite toughening mechanisms. Second, micropillar compression is explored experimentally as a high-fidelity method formore » extracting interface properties compared with traditional fiber push-out testing. Three significant interface properties that govern composite toughening were extracted. For a 50-nm-pyrolytic carbon interface, the following were observed: a fracture energy release rate of ~2.5 J/m 2, an internal friction coefficient of 0.25 ± 0.04, and a debond shear strength of 266 ± 24 MPa. Lastly, this research supports micromechanical evaluations as a unique bridge between theoretical physics models for microcrack propagation and empirically driven finite element models for bulk CFMCs.« less

Narayanaswamy's 1971 aging theory and material time

NASA Astrophysics Data System (ADS)

Dyre, Jeppe C.

2015-09-01

The Bochkov-Kuzovlev nonlinear fluctuation-dissipation theorem is used to derive Narayanaswamy's phenomenological theory of physical aging, in which this highly nonlinear phenomenon is described by a linear material-time convolution integral. A characteristic property of the Narayanaswamy aging description is material-time translational invariance, which is here taken as the basic assumption of the derivation. It is shown that only one possible definition of the material time obeys this invariance, namely, the square of the distance travelled from a configuration of the system far back in time. The paper concludes with suggestions for computer simulations that test for consequences of material-time translational invariance. One of these is the "unique-triangles property" according to which any three points on the system's path form a triangle such that two side lengths determine the third; this is equivalent to the well-known triangular relation for time-autocorrelation functions of aging spin glasses [L. F. Cugliandolo and J. Kurchan, J. Phys. A: Math. Gen. 27, 5749 (1994)]. The unique-triangles property implies a simple geometric interpretation of out-of-equilibrium time-autocorrelation functions, which extends to aging a previously proposed framework for such functions in equilibrium [J. C. Dyre, e-print arXiv:cond-mat/9712222 (1997)].

Ceramic composites: A review of toughening mechanisms and demonstration of micropillar compression for interface property extraction

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

Kabel, Joey; Hosemann, Peter; Zayachuk, Yevhen

We present that ceramic fiber–matrix composites (CFMCs) are exciting materials for engineering applications in extreme environments. By integrating ceramic fibers within a ceramic matrix, CFMCs allow an intrinsically brittle material to exhibit sufficient structural toughness for use in gas turbines and nuclear reactors. Chemical stability under high temperature and irradiation coupled with high specific strength make these materials unique and increasingly popular in extreme settings. This paper first offers a review of the importance and growing body of research on fiber–matrix interfaces as they relate to composite toughening mechanisms. Second, micropillar compression is explored experimentally as a high-fidelity method formore » extracting interface properties compared with traditional fiber push-out testing. Three significant interface properties that govern composite toughening were extracted. For a 50-nm-pyrolytic carbon interface, the following were observed: a fracture energy release rate of ~2.5 J/m 2, an internal friction coefficient of 0.25 ± 0.04, and a debond shear strength of 266 ± 24 MPa. Lastly, this research supports micromechanical evaluations as a unique bridge between theoretical physics models for microcrack propagation and empirically driven finite element models for bulk CFMCs.« less

Nitrogen-vacancy centers in diamond: nanoscale sensors for physics and biology.

PubMed

Schirhagl, Romana; Chang, Kevin; Loretz, Michael; Degen, Christian L

2014-01-01

Crystal defects in diamond have emerged as unique objects for a variety of applications, both because they are very stable and because they have interesting optical properties. Embedded in nanocrystals, they can serve, for example, as robust single-photon sources or as fluorescent biomarkers of unlimited photostability and low cytotoxicity. The most fascinating aspect, however, is the ability of some crystal defects, most prominently the nitrogen-vacancy (NV) center, to locally detect and measure a number of physical quantities, such as magnetic and electric fields. This metrology capacity is based on the quantum mechanical interactions of the defect's spin state. In this review, we introduce the new and rapidly evolving field of nanoscale sensing based on single NV centers in diamond. We give a concise overview of the basic properties of diamond, from synthesis to electronic and magnetic properties of embedded NV centers. We describe in detail how single NV centers can be harnessed for nanoscale sensing, including the physical quantities that may be detected, expected sensitivities, and the most common measurement protocols. We conclude by highlighting a number of the diverse and exciting applications that may be enabled by these novel sensors, ranging from measurements of ion concentrations and membrane potentials to nanoscale thermometry and single-spin nuclear magnetic resonance.

Sporulation environment influences spore properties in Bacillus: evidence and insights on underlying molecular and physiological mechanisms.

PubMed

Bressuire-Isoard, Christelle; Broussolle, Véronique; Carlin, Frédéric

2018-05-17

Bacterial spores are resistant to physical and chemical insults, which make them a major concern for public health and for industry. Spores help bacteria to survive extreme environmental conditions that vegetative cells cannot tolerate. Spore resistance and dormancy are important properties for applications in medicine, veterinary health, food safety, crop protection, and other domains. The resistance of bacterial spores results from a protective multilayered structure and from the unique composition of the spore core. The mechanisms of sporulation and germination, the first stage after breaking of dormancy, and organization of spore structure have been extensively studied in Bacillus species. This review aims to illustrate how far the structure, composition and properties of spores are shaped by the environmental conditions in which spores form. We look at the physiological and molecular mechanisms underpinning how sporulation media and environment deeply affect spore yield, spore properties like resistance to wet heat and physical and chemical agents, germination, and further growth. For example, spore core water content decreases as sporulation temperature increases, and resistance to wet heat increases. Controlling the fate of Bacillus spores is pivotal to controlling bacterial risks and process efficiencies in, for example, the food industry, and better control hinges on better understanding how sporulation conditions influence spore properties.

Proximity coupling in superconductor-graphene heterostructures.

PubMed

Lee, Gil-Ho; Lee, Hu-Jong

2018-05-01

This review discusses the electronic properties and the prospective research directions of superconductor-graphene heterostructures. The basic electronic properties of graphene are introduced to highlight the unique possibility of combining two seemingly unrelated physics, superconductivity and relativity. We then focus on graphene-based Josephson junctions, one of the most versatile superconducting quantum devices. The various theoretical methods that have been developed to describe graphene Josephson junctions are examined, together with their advantages and limitations, followed by a discussion on the advances in device fabrication and the relevant length scales. The phase-sensitive properties and phase-particle dynamics of graphene Josephson junctions are examined to provide an understanding of the underlying mechanisms of Josephson coupling via graphene. Thereafter, microscopic transport of correlated quasiparticles produced by Andreev reflections at superconducting interfaces and their phase-coherent behaviors are discussed. Quantum phase transitions studied with graphene as an electrostatically tunable 2D platform are reviewed. The interplay between proximity-induced superconductivity and the quantum-Hall phase is discussed as a possible route to study topological superconductivity and non-Abelian physics. Finally, a brief summary on the prospective future research directions is given.

Structural transformations of heat treated Co-less high entropy alloys

NASA Astrophysics Data System (ADS)

Mitrica, D.; Tudor, A.; Rinaldi, A.; Soare, V.; Predescu, C.; Berbecaru, A.; Stoiciu, F.; Badilita, V.

2018-03-01

Co is considered to be one of the main ingredients in superalloys. Co is considered a critical element and its substitution is difficult due to its unique ability to form high temperature stable structures with high mechanical and corrosion/oxidation resistance. High entropy alloys (HEA) represent a relatively new concept in material design. HEA are characterised by a high number of alloying elements, in unusually high proportion. Due to their specific particularities, high entropy alloys tend to form predominant solid solution structures that develop potentially high chemical, physical and mechanical properties. Present paper is studying Co-less high entropy alloys with high potential in severe environment applications. The high entropy alloys based on Al-Cr-Fe-Mn-Ni system were prepared by induction melting and casting under protective atmosphere. The as-cast specimens were heat treated at various temperatures to determine the structure and property behaviour. Samples taken before and after heat treatment were investigated for chemical, physical, structural and mechanical characteristics. Sigma phase composition and heat treatment parameters had major influence over the resulted alloy structure and properties.

Proximity coupling in superconductor-graphene heterostructures

NASA Astrophysics Data System (ADS)

Lee, Gil-Ho; Lee, Hu-Jong

2018-05-01

This review discusses the electronic properties and the prospective research directions of superconductor-graphene heterostructures. The basic electronic properties of graphene are introduced to highlight the unique possibility of combining two seemingly unrelated physics, superconductivity and relativity. We then focus on graphene-based Josephson junctions, one of the most versatile superconducting quantum devices. The various theoretical methods that have been developed to describe graphene Josephson junctions are examined, together with their advantages and limitations, followed by a discussion on the advances in device fabrication and the relevant length scales. The phase-sensitive properties and phase-particle dynamics of graphene Josephson junctions are examined to provide an understanding of the underlying mechanisms of Josephson coupling via graphene. Thereafter, microscopic transport of correlated quasiparticles produced by Andreev reflections at superconducting interfaces and their phase-coherent behaviors are discussed. Quantum phase transitions studied with graphene as an electrostatically tunable 2D platform are reviewed. The interplay between proximity-induced superconductivity and the quantum-Hall phase is discussed as a possible route to study topological superconductivity and non-Abelian physics. Finally, a brief summary on the prospective future research directions is given.

Separable Bilayer Microfiltration Device for Label-Free Enrichment of Viable Circulating Tumor Cells.

PubMed

Hao, Sijie; Nisic, Merisa; He, Hongzhang; Tai, Yu-Chong; Zheng, Si-Yang

2017-01-01

Analysis of rare circulating tumor cells enriched from metastatic cancer patients yields critical information on disease progression, therapy response, and the mechanism of cancer metastasis. Here we describe in detail a label-free enrichment process of circulating tumor cells based on its unique physical properties (size and deformability). Viable circulating tumor cells can be successfully enriched and analyzed, or easily released for further characterization due to the novel separable two-layer design.

Exact Recovery of Chaotic Systems from Highly Corrupted Data

DTIC Science & Technology

2016-08-01

dimension to reconstruct a state space which preserves the topological properties of the original system. In [CM87, RS92], the authors use the singular...in high dimensional nonlinear functional spaces [Spr94, SL00, LCC04]. In this work, we bring together connections between compressed sensing, splitting... compact , connected attractor Λ and the flow admits a unique so-called “physical" measure µ with supp(µ) = Λ. An invariant probability measure µ for a flow

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

Lee, Peter L; Rhyne, James J

The unique properties of synchrotron radiation are its continuous spectrum, high flux and brightness, and high coherence, which make it an indispensable tool in the exploration of matter. The wavelengths of the emitted photons span a range of dimensions from the atomic level to biological cells, thereby providing incisive probes for advanced research in materials science, physical and chemical sciences, metrology, geosciences, environmental sciences, biosciences, medical sciences, and pharmaceutical sciences. The features of synchrotron radiation are especially well matched to the needs of nanoscience.

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

Lemaire, Paul C.; Oldham, Christopher J.; Parsons, Gregory N., E-mail: gnp@ncsu.edu

Molecular layer deposition (MLD) of “metalcones,” including alucone, zincone, titanicone, and others, involves self-limiting half-reactions between organic and organometallic (or metal-halide) reactants. Studies have typically focused on metal precursors reacting with ethylene glycol or glycerol to form the films' polymeric O-M-O-(CH{sub x}){sub y}-O-M-O repeat units. The authors report new MLD materials that incorporate tertiary amine groups into the organic linkage. Specifically, reacting triethanolamine (TEA) with either trimethylaluminum or titanium tetrachloride produces TEA-alucone (Al-TEA) and TEA-titanicone (Ti-TEA), respectively, and the amine group leads to unique physical and optical properties. Fourier-transform infrared (FTIR) analysis confirms that the films have prominent C-H, C-N,more » and M-O-C peaks, consistent with the expected bond structure. When exposed to vapors, including water, alcohol, or ammonia, the Ti-TEA films changed their visible color within minutes and increased physical thickness by >35%. The Al-TEA showed significantly less response. X-ray photoelectron spectroscopy and FTIR suggest that HCl generated during MLD coordinates to the amine forming a quaternary ammonium salt that readily binds adsorbates via hydrogen bonding. The visible color change is reversible, and ellipsometry confirms that the color change results from vapor absorption. The unique absorptive and color-changing properties of the TEA-metalcone films point to new possible applications for MLD materials in filtration, chemical absorption, and multifunctional chemical separations/sensing device systems.« less

Surfactants in the management of rhinopathologies

PubMed Central

Rosen, Philip L.; Palmer, James N.; O'Malley, Bert W.

2013-01-01

Background: Surfactants are a class of amphiphilic surface active compounds that show several unique physical properties at liquid–liquid or liquid–solid surface interfaces including the ability to increase the solubility of substances, lower the surface tension of a liquid, and decrease friction between two mediums. Because of these unique physical properties several in vitro, ex vivo, and human trials have examined the role of surfactants as stand-alone or adjunct therapy in recalcitrant chronic rhinosinusitis (CRS). Methods: A review of the literature was performed. Results: The data from three different surfactants have been examined in this review: citric acid zwitterionic surfactant (CAZS; Medtronic ENT, Jacksonville FL), Johnson's Baby Shampoo (Johnson & Johnson, New Brunswick NJ), and SinuSurf (NeilMed Pharmaceuticals, Santa Rosa, CA). Dilute surfactant therapy shows in vitro antimicrobial effects with modest inhibition of bacterial biofilm formation. In patients with CRS, surfactants may improve symptoms, most likely through its mucolytic effects. In addition, surfactants have several distinct potential benefits including their ability to improve an irrigant's penetration of the nonoperated sinus and their synergistic effects with antibiotics. However, surfactants potential for nasal irritation and possible transient ciliotoxicity may limit their use. Conclusion: Recent data suggest a possible therapeutic role of surfactants in treating rhinopathologies associated with mucostasis. Further investigation, including a standardization of surfactant formulations, is warranted to further elucidate the potential benefits and drawbacks of this therapy. PMID:23710951

Quantum simulation of 2D topological physics in a 1D array of optical cavities

PubMed Central

Luo, Xi-Wang; Zhou, Xingxiang; Li, Chuan-Feng; Xu, Jin-Shi; Guo, Guang-Can; Zhou, Zheng-Wei

2015-01-01

Orbital angular momentum of light is a fundamental optical degree of freedom characterized by unlimited number of available angular momentum states. Although this unique property has proved invaluable in diverse recent studies ranging from optical communication to quantum information, it has not been considered useful or even relevant for simulating nontrivial physics problems such as topological phenomena. Contrary to this misconception, we demonstrate the incredible value of orbital angular momentum of light for quantum simulation by showing theoretically how it allows to study a variety of important 2D topological physics in a 1D array of optical cavities. This application for orbital angular momentum of light not only reduces required physical resources but also increases feasible scale of simulation, and thus makes it possible to investigate important topics such as edge-state transport and topological phase transition in a small simulator ready for immediate experimental exploration. PMID:26145177

Quantum simulation of 2D topological physics in a 1D array of optical cavities.

PubMed

Luo, Xi-Wang; Zhou, Xingxiang; Li, Chuan-Feng; Xu, Jin-Shi; Guo, Guang-Can; Zhou, Zheng-Wei

2015-07-06

Orbital angular momentum of light is a fundamental optical degree of freedom characterized by unlimited number of available angular momentum states. Although this unique property has proved invaluable in diverse recent studies ranging from optical communication to quantum information, it has not been considered useful or even relevant for simulating nontrivial physics problems such as topological phenomena. Contrary to this misconception, we demonstrate the incredible value of orbital angular momentum of light for quantum simulation by showing theoretically how it allows to study a variety of important 2D topological physics in a 1D array of optical cavities. This application for orbital angular momentum of light not only reduces required physical resources but also increases feasible scale of simulation, and thus makes it possible to investigate important topics such as edge-state transport and topological phase transition in a small simulator ready for immediate experimental exploration.

Physically Unclonable Cryptographic Primitives by Chemical Vapor Deposition of Layered MoS2.

PubMed

Alharbi, Abdullah; Armstrong, Darren; Alharbi, Somayah; Shahrjerdi, Davood

2017-12-26

Physically unclonable cryptographic primitives are promising for securing the rapidly growing number of electronic devices. Here, we introduce physically unclonable primitives from layered molybdenum disulfide (MoS 2 ) by leveraging the natural randomness of their island growth during chemical vapor deposition (CVD). We synthesize a MoS 2 monolayer film covered with speckles of multilayer islands, where the growth process is engineered for an optimal speckle density. Using the Clark-Evans test, we confirm that the distribution of islands on the film exhibits complete spatial randomness, hence indicating the growth of multilayer speckles is a spatial Poisson process. Such a property is highly desirable for constructing unpredictable cryptographic primitives. The security primitive is an array of 2048 pixels fabricated from this film. The complex structure of the pixels makes the physical duplication of the array impossible (i.e., physically unclonable). A unique optical response is generated by applying an optical stimulus to the structure. The basis for this unique response is the dependence of the photoemission on the number of MoS 2 layers, which by design is random throughout the film. Using a threshold value for the photoemission, we convert the optical response into binary cryptographic keys. We show that the proper selection of this threshold is crucial for maximizing combination randomness and that the optimal value of the threshold is linked directly to the growth process. This study reveals an opportunity for generating robust and versatile security primitives from layered transition metal dichalcogenides.

Recent advances in chemical functionalization of nanoparticles with biomolecules for analytical applications.

PubMed

Oh, Ju-Hwan; Park, Do Hyun; Joo, Jang Ho; Lee, Jae-Seung

2015-11-01

The recent synthetic development of a variety of nanoparticles has led to their widespread application in diagnostics and therapeutics. In particular, the controlled size and shape of nanoparticles precisely determine their unique chemical and physical properties, which is highly attractive for accurate analysis of given systems. In addition to efforts toward controlling the synthesis and properties of nanoparticles, the surface functionalization of nanoparticles with biomolecules has been intensively investigated since the mid-1990s. The complicated yet programmable properties of biomolecules have proved to substantially enhance and enrich the novel functions of nanoparticles to achieve "smart" nanoparticle materials. In this review, the advances in chemical functionalization of four types of representative nanoparticle with DNA and protein molecules in the past five years are critically reviewed, and their future trends are predicted.

Studies of Thermophysical Properties of Metals and Semiconductors by Containerless Processing Under Microgravity

NASA Technical Reports Server (NTRS)

Seidel, A.; Soellner, W.; Stenzel, C.

2012-01-01

Electromagnetic levitation under microgravity provides unique opportunities for the investigation of liquid metals, alloys and semiconductors, both above and below their melting temperatures, with minimized disturbances of the sample under investigation. The opportunity to perform such experiments will soon be available on the ISS with the EML payload which is currently being integrated. With its high-performance diagnostics systems EML allows to measure various physical properties such as heat capacity, enthalpy of fusion, viscosity, surface tension, thermal expansion coefficient, and electrical conductivity. In studies of nucleation and solidification phenomena the nucleation kinetics, phase selection, and solidification velocity can be determined. Advanced measurement capabilities currently being studied include the measurement and control of the residual oxygen content of the process atmosphere and a complementary inductive technique to measure thermophysical properties.

Ultra-High Molecular Weight Polyethylene: Influence of the Chemical, Physical and Mechanical Properties on the Wear Behavior. A Review

PubMed Central

Bellare, Anuj; Bistolfi, Alessandro

2017-01-01

Ultra-high molecular weight polyethylene (UHMWPE) is the most common bearing material in total joint arthroplasty due to its unique combination of superior mechanical properties and wear resistance over other polymers. A great deal of research in recent decades has focused on further improving its performances, in order to provide durable implants in young and active patients. From “historical”, gamma-air sterilized polyethylenes, to the so-called first and second generation of highly crosslinked materials, a variety of different formulations have progressively appeared in the market. This paper reviews the structure–properties relationship of these materials, with a particular emphasis on the in vitro and in vivo wear performances, through an analysis of the existing literature. PMID:28773153

Cluster Physics with Merging Galaxy Clusters

NASA Astrophysics Data System (ADS)

Molnar, Sandor

Collisions between galaxy clusters provide a unique opportunity to study matter in a parameter space which cannot be explored in our laboratories on Earth. In the standard ΛCDM model, where the total density is dominated by the cosmological constant (Λ) and the matter density by cold dark matter (CDM), structure formation is hierarchical, and clusters grow mostly by merging. Mergers of two massive clusters are the most energetic events in the universe after the Big Bang, hence they provide a unique laboratory to study cluster physics. The two main mass components in clusters behave differently during collisions: the dark matter is nearly collisionless, responding only to gravity, while the gas is subject to pressure forces and dissipation, and shocks and turbulence are developed during collisions. In the present contribution we review the different methods used to derive the physical properties of merging clusters. Different physical processes leave their signatures on different wavelengths, thus our review is based on a multifrequency analysis. In principle, the best way to analyze multifrequency observations of merging clusters is to model them using N-body/HYDRO numerical simulations. We discuss the results of such detailed analyses. New high spatial and spectral resolution ground and space based telescopes will come online in the near future. Motivated by these new opportunities, we briefly discuss methods which will be feasible in the near future in studying merging clusters.

Solar system plasma waves

NASA Technical Reports Server (NTRS)

Gurnett, Donald A.

1995-01-01

An overview is given of spacecraft observations of plasma waves in the solar system. In situ measurements of plasma phenomena have now been obtained at all of the planets except Mercury and Pluto, and in the interplanetary medium at heliocentric radial distances ranging from 0.29 to 58 AU. To illustrate the range of phenomena involved, we discuss plasma waves in three regions of physical interest: (1) planetary radiation belts, (2) planetary auroral acceleration regions and (3) the solar wind. In each region we describe examples of plasma waves that are of some importance, either due to the role they play in determining the physical properties of the plasma, or to the unique mechanism involved in their generation.

A review on III-V core-multishell nanowires: growth, properties, and applications

NASA Astrophysics Data System (ADS)

Royo, Miquel; De Luca, Marta; Rurali, Riccardo; Zardo, Ilaria

2017-04-01

This review focuses on the emerging field of core-multishell (CMS) semiconductor nanowires (NWs). In these kinds of wires, a NW grown vertically on a substrate acts as a template for the coaxial growth of two or more layers wrapped around it. Thanks to the peculiar geometry, the strain is partially released along the radial direction, thus allowing the creation of fascinating heterostructures, even based on lattice mismatched materials that would hardly grow in a planar geometry. Enabling the unique bridging of the 1D nature of NWs with the exciting properties of 2D heterostructures, these novel systems are becoming attractive for material science, as well as fundamental and applied physics. We will focus on NWs made of III-V and III-V-based alloys as they represent a model system in which present growth techniques have reached a high degree of control on the material structural properties, and many physical properties have been assessed, from both the theoretical and experimental points of view. In particular, we provide an overview on the growth methods and structural properties of CMS NWs, on the modulation doping mechanisms enabled by these heterostructures, on the effects of a magnetic field, and on the phononic and optical properties typical of CMS NWs. Moreover, we review the main technological applications based on these systems, such as optoelectronic and photovoltaic devices.

Relaxation processes and physical aging in metallic glasses

NASA Astrophysics Data System (ADS)

Ruta, B.; Pineda, E.; Evenson, Z.

2017-12-01

Since their discovery in the 1960s, metallic glasses have continuously attracted much interest across the physics and materials science communities. In the forefront are their unique properties, which hold the alluring promise of broad application in fields as diverse as medicine, environmental science and engineering. However, a major obstacle to their wide-spread commercial use is their inherent temporal instability arising from underlying relaxation processes that can dramatically alter their physical properties. The result is a physical aging process which can bring about degradation of mechanical properties, namely through embrittlement and catastrophic mechanical failure. Understanding and controlling the effects of aging will play a decisive role in our on-going endeavor to advance the use of metallic glasses as structural materials, as well as in the more general comprehension of out-of-equilibrium dynamics in complex systems. This review presents an overview of the current state of the art in the experimental advances probing physical aging and relaxation processes in metallic glasses. Similarities and differences between other hard and soft matter glasses are highlighted. The topic is discussed in a multiscale approach, first presenting the key features obtained in macroscopic studies, then connecting them to recent novel microscopic investigations. Particular emphasis is put on the occurrence of distinct relaxation processes beyond the main structural process in viscous metallic melts and their fate upon entering the glassy state, trying to disentangle results and formalisms employed by the different groups of the glass-science community. A microscopic viewpoint is presented, in which physical aging manifests itself in irreversible atomic-scale processes such as avalanches and intermittent dynamics, ascribed to the existence of a plethora of metastable glassy states across a complex energy landscape. Future experimental challenges and the comparison with recent theoretical and numerical simulations are discussed as well.

Photo-crosslinked PDMSstar-PEG Hydrogels: Synthesis, Characterization, and Potential Application for Tissue Engineering Scaffolds

PubMed Central

Hou, Yaping; Schoener, Cody A.; Regan, Katherine R.; Munoz-Pinto, Dany; Hahn, Mariah S.; Grunlan, Melissa A.

2010-01-01

Inorganic-organic hydrogels with tunable chemical and physical properties were prepared from methacrylated star polydimethylsiloxane (PDMSstar-MA) and diacrylated poly(ethylene glycol) (PEG-DA) for use as tissue engineering scaffolds. Eighteen compositionally unique hydrogels were prepared by photo-crosslinking varying weight ratios of PEG-DA and PDMSstar-MA of different molecular weights (Mn): PEG-DA (Mn = 3.4k and 6k g/mol) and PDMSstar-MA (Mn = 1.8k, 5k and 7k g/mol). Introduction of PDMSstar-MA caused formation of discrete PDMS-enriched microparticles dispersed within the PEG matrix. The swelling ratio, mechanical properties in tension and compression, non-specific protein adhesion, controlled introduction of bioactivity and cytotoxicity of hydrogels were studied. This library of inorganic-organic hydrogels with tunable properties provides a useful platform to study the effect of scaffold properties on cell behavior. PMID:20146518

Amyloids and prions in plants: Facts and perspectives.

PubMed

Antonets, K S; Nizhnikov, A A

2017-09-03

Amyloids represent protein fibrils that have highly ordered structure with unique physical and chemical properties. Amyloids have long been considered lethal pathogens that cause dozens of incurable diseases in humans and animals. Recent data show that amyloids may not only possess pathogenic properties but are also implicated in the essential biological processes in a variety of prokaryotes and eukaryotes. Functional amyloids have been identified in archaea, bacteria, fungi, and animals, including humans. Plants are one of the most poorly studied groups of organisms in the field of amyloid biology. Although amyloid properties have not been shown under native conditions for any plant protein, studies demonstrating amyloid properties for a set of plant proteins in vitro or in heterologous systems in vivo have been published in recent years. In this review, we systematize the data on the amyloidogenic proteins of plants and their functions and discuss the perspectives of identifying novel amyloids using bioinformatic and proteomic approaches.

Airborne Lidar Measurements of Aerosol Optical Properties During SAFARI-2000

NASA Technical Reports Server (NTRS)

McGill, M. J.; Hlavka, D. L.; Hart, W. D.; Welton, E. J.; Campbell, J. R.; Starr, David OC. (Technical Monitor)

2002-01-01

The Cloud Physics Lidar (CPL) operated onboard the NASA ER-2 high altitude aircraft during the SAFARI-2000 field campaign. The CPL provided high spatial resolution measurements of aerosol optical properties at both 1064 nm and 532 nm. We present here results of planetary boundary layer (PBL) aerosol optical depth analysis and profiles of aerosol extinction. Variation of optical depth and extinction are examined as a function of regional location. The wide-scale aerosol mapping obtained by the CPL is a unique data set that will aid in future studies of aerosol transport. Comparisons between the airborne CPL and ground-based MicroPulse Lidar Network (MPL-Net) sites are shown to have good agreement.

Experimental study on Response Parameters of Ni-rich NiTi Shape Memory Alloy during Wire Electric Discharge Machining

NASA Astrophysics Data System (ADS)

Bisaria, Himanshu; Shandilya, Pragya

2018-03-01

Nowadays NiTi SMAs are gaining more prominence due to their unique properties such as superelasticity, shape memory effect, high fatigue strength and many other enriched physical and mechanical properties. The current studies explore the effect of machining parameters namely, peak current (Ip), pulse off time (TOFF), and pulse on time (TON) on wire wear ratio (WWR), and dimensional deviation (DD) in WEDM. It was found that high discharge energy was mainly ascribed to high WWR and DD. The WWR and DD increased with the increase in pulse on time and peak current whereas high pulse off time was favourable for low WWR and DD.

Tubular nanostructured materials for bioapplications

NASA Astrophysics Data System (ADS)

Xie, Jining; Chen, Linfeng; Srivatsan, Malathi; Varadan, Vijay K.

2009-03-01

Tubular nanomaterials possess hollow structures as well as high aspect ratios. In addition to their unique physical and chemical properties induced by their nanoscale dimensions, their inner voids and outer surfaces make them ideal candidates for a number of biomedical applications. In this work, three types of tubular nanomaterials including carbon nanotubes, hematite nanotubes, and maghemite nanotubes, were synthesized by different chemical techniques. Their structural and crystalline properties were characterized. For potential bioapplications of tubular nanomaterials, experimental investigations were carried out to demonstrate the feasibility of using carbon nanotubes, hematite nanotubes, and maghemite nanotubes in glucose sensing, neuronal growth, and drug delivery, respectively. Preliminary results show the promise of tubular nanomaterials in future biomedical applications.

Metal matrix coated fiber composites and the methods of manufacturing such composites

DOEpatents

Weeks, Jr., Joseph K.; Gensse, Chantal

1993-01-01

A fiber coating which allows ceramic or metal fibers to be wetted by molten metals is disclosed. The coating inhibits degradation of the physical properties caused by chemical reaction between the fiber and the coating itself or between the fiber and the metal matrix. The fiber coating preferably includes at least a wetting layer, and in some applications, a wetting layer and a barrier layer between the fiber and the wetting layer. The wetting layer promotes fiber wetting by the metal matrix. The barrier layer inhibits fiber degradation. The fiber coating permits the fibers to be infiltrated with the metal matrix resulting in composites having unique properties not obtainable in pure materials.

Metal matrix coated fiber composites and the methods of manufacturing such composites

DOEpatents

Weeks, J.K. Jr.; Gensse, C.

1993-09-14

A fiber coating which allows ceramic or metal fibers to be wetted by molten metals is disclosed. The coating inhibits degradation of the physical properties caused by chemical reaction between the fiber and the coating itself or between the fiber and the metal matrix. The fiber coating preferably includes at least a wetting layer, and in some applications, a wetting layer and a barrier layer between the fiber and the wetting layer. The wetting layer promotes fiber wetting by the metal matrix. The barrier layer inhibits fiber degradation. The fiber coating permits the fibers to be infiltrated with the metal matrix resulting in composites having unique properties not obtainable in pure materials. 8 figures.

Size matters: gold nanoparticles in targeted cancer drug delivery

PubMed Central

Dreaden, Erik C; Austin, Lauren A; Mackey, Megan A; El-Sayed, Mostafa A

2013-01-01

Cancer is the current leading cause of death worldwide, responsible for approximately one quarter of all deaths in the USA and UK. Nanotechnologies provide tremendous opportunities for multimodal, site-specific drug delivery to these disease sites and Au nanoparticles further offer a particularly unique set of physical, chemical and photonic properties with which to do so. This review will highlight some recent advances, by our laboratory and others, in the use of Au nanoparticles for systemic drug delivery to these malignancies and will also provide insights into their rational design, synthesis, physiological properties and clinical/preclinical applications, as well as strategies and challenges toward the clinical implementation of these constructs moving forward. PMID:22834077

Graphene Chemical Sensor for Heliophysics Applications

NASA Technical Reports Server (NTRS)

Sultana, Mahmooda; Herrero, Fred; Khazanov, George

2013-01-01

Graphene is a single layer of carbon atoms that offer a unique set of advantages as a chemical sensor due to a number of its inherent properties. Graphene has been explored as a gas sensor for a variety of gases, and molecular sensitivity has been demonstrated by measuring the change in electrical properties due to the adsorption of target species. In this paper, we discuss the development of an array of chemical sensors based on graphene and its relevance to plasma physics due to its sensitivity to radical species such as oxonium, hydron and the corresponding neutrals. We briefly discuss the great impact such sensors will have on a number of heliophysics applications such as ground-based manifestations of space weather.

Graphene electrochemistry: an overview of potential applications.

PubMed

Brownson, Dale A C; Banks, Craig E

2010-11-01

Graphene, a 2D nanomaterial that possesses spectacular physical, chemical and thermal properties, has caused immense excitement amongst scientists since its freestanding form was isolated in 2004. With research into graphene rife, it promises enhancements and vast applicability within many industrial aspects. Furthermore, graphene possesses a vast array of unique and highly desirable electrochemical properties, and it is this application that offers the most enthralling and spectacular journey. We present a review of the current literature concerning the electrochemical applications and advancements of graphene, starting with its use as a sensor substrate through to applications in energy production and storage, depicting the truly remarkable journey of a material that has just come of age.

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

Bishnoi, Dimple

In this paper, we demonstrate theoretically that the Quantum dots are quite interesting for the electronics industry. Semiconductor quantum dots (QDs) are nanometer-scale crystals, which have unique photo physical, quantum electrical properties, size-dependent optical properties, There small size means that electrons do not have to travel as far as with larger particles, thus electronic devices can operate faster. Cheaper than modern commercial solar cells while making use of a wider variety of photon energies, including “waste heat” from the sun’s energy. Quantum dots can be used in tandem cells, which are multi junction photovoltaic cells or in the intermediate bandmore » setup. PbSe (lead selenide) is commonly used in quantum dot solar cells.« less

Bose-Einstein condensate of rigid rotor molecules

NASA Astrophysics Data System (ADS)

Jones, Evan; Smith, Joseph; Rittenhouse, Seth; Peden, Brandon; Wilson, Ryan

2017-04-01

We study the ground state phases of a quasi-two-dimensional Bose-Einstein condensate (BEC) of dipolar rigid rotor molecules subject to a DC electric field. In the high-field limit, this system acquires the properties of the fully polarized dipolar BEC, which exhibits a roton-maxon excitation spectrum, and has been thoroughly studied in the theoretical literature. In the weak-field limit, however, qualitatively new physics emerges due to the competition between the (weak) applied field and internal electric fields, which are produced by the molecules themselves. We characterize the ground states of this system, and study its unique dielectric properties. We gratefully acknowledge support from the National Science Foundation under Grant No. PHYS-1516421.

One-Dimensional Metal-Oxide Nanostructures for Solar Photocatalytic Water-Splitting

NASA Astrophysics Data System (ADS)

Wang, Fengyun; Song, Longfei; Zhang, Hongchao; Luo, Linqu; Wang, Dong; Tang, Jie

2017-08-01

Because of their unique physical and chemical properties, one-dimensional (1-D) metal-oxide nanostructures have been extensively applied in the areas of gas sensors, electrochromic devices, nanogenerators, and so on. Solar water-splitting has attracted extensive research interest because hydrogen generated from solar-driven water splitting is a clean, sustainable, and abundant energy source that not only solves the energy crisis, but also protects the environment. In this comprehensive review, the main synthesis methods, properties, and especially prominent applications in solar water splitting of 1-D metal-oxides, including titanium dioxide (TiO2), zinc oxide (ZnO), tungsten trioxide (WO3), iron oxide (Fe2O3), and copper oxide (CuO) are fully discussed.

PropBase Query Layer: a single portal to UK subsurface physical property databases

NASA Astrophysics Data System (ADS)

Kingdon, Andrew; Nayembil, Martin L.; Richardson, Anne E.; Smith, A. Graham

2013-04-01

Until recently, the delivery of geological information for industry and public was achieved by geological mapping. Now pervasively available computers mean that 3D geological models can deliver realistic representations of the geometric location of geological units, represented as shells or volumes. The next phase of this process is to populate these with physical properties data that describe subsurface heterogeneity and its associated uncertainty. Achieving this requires capture and serving of physical, hydrological and other property information from diverse sources to populate these models. The British Geological Survey (BGS) holds large volumes of subsurface property data, derived both from their own research data collection and also other, often commercially derived data sources. This can be voxelated to incorporate this data into the models to demonstrate property variation within the subsurface geometry. All property data held by BGS has for many years been stored in relational databases to ensure their long-term continuity. However these have, by necessity, complex structures; each database contains positional reference data and model information, and also metadata such as sample identification information and attributes that define the source and processing. Whilst this is critical to assessing these analyses, it also hugely complicates the understanding of variability of the property under assessment and requires multiple queries to study related datasets making extracting physical properties from these databases difficult. Therefore the PropBase Query Layer has been created to allow simplified aggregation and extraction of all related data and its presentation of complex data in simple, mostly denormalized, tables which combine information from multiple databases into a single system. The structure from each relational database is denormalized in a generalised structure, so that each dataset can be viewed together in a common format using a simple interface. Data are re-engineered to facilitate easy loading. The query layer structure comprises tables, procedures, functions, triggers, views and materialised views. The structure contains a main table PRB_DATA which contains all of the data with the following attribution: • a unique identifier • the data source • the unique identifier from the parent database for traceability • the 3D location • the property type • the property value • the units • necessary qualifiers • precision information and an audit trail Data sources, property type and units are constrained by dictionaries, a key component of the structure which defines what properties and inheritance hierarchies are to be coded and also guides the process as to what and how these are extracted from the structure. Data types served by the Query Layer include site investigation derived geotechnical data, hydrogeology datasets, regional geochemistry, geophysical logs as well as lithological and borehole metadata. The size and complexity of the data sets with multiple parent structures requires a technically robust approach to keep the layer synchronised. This is achieved through Oracle procedures written in PL/SQL containing the logic required to carry out the data manipulation (inserts, updates, deletes) to keep the layer synchronised with the underlying databases either as regular scheduled jobs (weekly, monthly etc) or invoked on demand. The PropBase Query Layer's implementation has enabled rapid data discovery, visualisation and interpretation of geological data with greater ease, simplifying the parametrisation of 3D model volumes and facilitating the study of intra-unit heterogeneity.

Physical Property Investigation of Contemporary Glass lonomer and Resin Modified Glass lonomer Restorative Materials

DTIC Science & Technology

2016-05-24

racteristics. 7•13•14 These modifications have included the use of alternative polyacids, 7•15•16 water- activated dehydrated polyacid powders, 7•15•17...cermets, 18 metal additions, 19’ 21 smaller glass particle size, 22 antibacterial agent s, n.24 different glass compositions, 15•25 and most recently...methacrylate (HEMA) or is uniquely grafted on the polyalkenoate acid chain. These monomers polymerize either by external photo activation or by an

Mechanical control of tissue and organ development

PubMed Central

Mammoto, Tadanori; Ingber, Donald E.

2010-01-01

Many genes and molecules that drive tissue patterning during organogenesis and tissue regeneration have been discovered. Yet, we still lack a full understanding of how these chemical cues induce the formation of living tissues with their unique shapes and material properties. Here, we review work based on the convergence of physics, engineering and biology that suggests that mechanical forces generated by living cells are as crucial as genes and chemical signals for the control of embryological development, morphogenesis and tissue patterning. PMID:20388652

Micro-Raman Analysis of Irradiated Diamond Films

NASA Technical Reports Server (NTRS)

Newton, R. L.; Munafo, Paul M. (Technical Monitor)

2002-01-01

Owing to its unique and robust physical properties, diamond is a much sought after material for use in advanced technologies such as Microelectromechanical Systems (MEMS). The volume and weight savings promised by MEMS-based devices are of particular interest to spaceflight applications. However, much basic materials science research remains to be completed in this field. Results of micro-Raman analysis of proton (1015 - 1017 H+/cm2 doses) irradiated chemical vapor deposited (CVD) diamond reveals that the microstructure is retained even after high radiation exposure.

Goldstone solar system radar

NASA Technical Reports Server (NTRS)

Jurgens, R. F.; Clark, P. E.; Goldstein, R. M.; Ostro, S. J.; Slade, M. A.; Thompson, T. W.; Saunders, R. S.

1986-01-01

Information is provided about physical nature planetary surfaces and their topography as well as dynamical properties such as orbits and spin states using ground based radar as a remote sensing tool. Accessible targets are the terrestrial planets: the Earth's Moon, Mercury, Venus and Mars, the outer planets rings and major moons, and many transient objects such as asteroids and comets. Data acquisition utilizes the unique facilities of the Goldstone Deep Space Network, occasionally the Arecibo radar, and proposed use of the VLA (very large array).

Recent advances in 2D materials for photocatalysis.

PubMed

Luo, Bin; Liu, Gang; Wang, Lianzhou

2016-04-07

Two-dimensional (2D) materials have attracted increasing attention for photocatalytic applications because of their unique thickness dependent physical and chemical properties. This review gives a brief overview of the recent developments concerning the chemical synthesis and structural design of 2D materials at the nanoscale and their applications in photocatalytic areas. In particular, recent progress on the emerging strategies for tailoring 2D material-based photocatalysts to improve their photo-activity including elemental doping, heterostructure design and functional architecture assembly is discussed.

Geometric Modeling for Computer Vision

DTIC Science & Technology

1974-10-01

within a distance R of a locus X ,Y,Z; spatial uniqueness refers to the property that physical solids can not occupy the same space simultaneously. A...density functions W«p( X ,Y,Z). Unfortunately such density functions can no» be writtrn out for objects such as a typing chair or a plastic horse...be approximated by a surface function 2 = F( X ,Y). For example landscape may be represented by geodetic maps in such a 2-D fashion. By definition, a

Neurobiology as Information Physics

PubMed Central

Street, Sterling

2016-01-01

This article reviews thermodynamic relationships in the brain in an attempt to consolidate current research in systems neuroscience. The present synthesis supports proposals that thermodynamic information in the brain can be quantified to an appreciable degree of objectivity, that many qualitative properties of information in systems of the brain can be inferred by observing changes in thermodynamic quantities, and that many features of the brain’s anatomy and architecture illustrate relatively simple information-energy relationships. The brain may provide a unique window into the relationship between energy and information. PMID:27895560

The slow X-ray pulsar SXP 1062 and associated supernova remnant in the Wing of the Small Magellanic Cloud

NASA Astrophysics Data System (ADS)

Oskinova, L. M.; Guerrero, M. A.; Hénault-Brunet, V.; Sun, W.; Chu, Y.-H.; Evans, C.; Gallagher, J. S.; Gruendl, R. A.; Reyes-Iturbide, J.

2013-03-01

SXP 1062 is an exceptional case of a young neutron star in a wind-fed high-mass X-ray binary associated with a supernova remnant. A unique combination of measured spin period, its derivative, luminosity and young age makes this source a key probe for the physics of accretion and neutron star evolution. Theoretical models proposed to explain the properties of SXP 1062 shall be tested with new data.

Self-organized, highly luminescent CdSe nanorod-DNA complexes.

PubMed

Artemyev, Mikhail; Kisiel, Dmitry; Abmiotko, Sergey; Antipina, Maria N; Khomutov, Gennady B; Kislov, Vladimir V; Rakhnyanskaya, Anna A

2004-09-01

DNA molecules are useful building blocks and nanotemplates for controllable fabrication of various bioinorganic nanostructures due to their unique physical-chemical properties and recognition capabilities and the synthetic availability of desired nucleotide sequences and length. We have synthesized novel DNA complexes with positively charged, highly luminescent CdSe nanorods that can be self-organized into filamentary, netlike, or spheroidal nanostructures. DNA-CdSe-nanorod filaments possess strongly linearly polarized photoluminescence due to the unidirectional orientation of nanorods along the filaments. Copyright 2004 American Chemical Society

Environmental Assessment for Termination of Lease and the Transfer of Property Back to the Landowner for the Morgan City, LA, Tethered Aerostat Radar System (TARS) Site

DTIC Science & Technology

2010-08-01

infrastructure would be affected under Alternative A since all buildings, utility systems, roads, pavements, fences, etc. would be removed. Physical... affect the TARS program objectives. 1.4 ORGANIZATION OF THE DOCUMENT This EA is organized into seven chapters plus appendices. Chapter 1...Action affects public health or safety; • Unique characteristics of the geographic area such as proximity to historic or cultural resources, park

Epitaxial strain effect on the physical properties of layered ruthenate and iridate thin films

NASA Astrophysics Data System (ADS)

Miao, Ludi

Transition metal oxides have attracted widespread attention due to their broad range of fascinating exotic phenomena such as multiferroicity, superconductivity, colossal magnetoresistance and metal-to-insulator transition. Due to the interplay between spin, charge, lattice and orbital degrees of freedom of strongly correlated d electrons, these physical properties are extremely sensitive to the external perturbations such as magnetic field, charge carrier doping and pressure, which provide a unique chance in search for novel exotic quantum states. Ruthenate systems are a typical strongly correlated system, with rich ordered states and their properties are extremely sensitive to external stimuli. Recently, the experimental observation of spin-orbit coupling induced Mott insulator in Sr2IrO4 as well as the theoretical prediction of topological insulating state in other iridates, have attracted tremendous interest in the physics of strong correlation and spin-orbit coupling in 4d/5d compounds. We observe an itinerant ferromagnetic ground state of Ca2 RuO4 film in stark contrast to the Mott-insulating state in bulk Ca2RuO4. We have also established the epitaxial strain effect on the transport and magnetic properties for the (Ca,Sr) 2RuO4 thin films. For Sr2IrO4 thin films, we will show that the Jeff = 1/2 moment orientation can be modulated by epitaxial strain. In addition, we discovered novel Ba 7Ir3O13+x thin films which exhibit colossal permittivity.

Avian photoreceptor patterns represent a disordered hyperuniform solution to a multiscale packing problem

NASA Astrophysics Data System (ADS)

Jiao, Yang; Lau, Timothy; Hatzikirou, Haralampos; Meyer-Hermann, Michael; Corbo, Joseph C.; Torquato, Salvatore

2014-02-01

Optimal spatial sampling of light rigorously requires that identical photoreceptors be arranged in perfectly regular arrays in two dimensions. Examples of such perfect arrays in nature include the compound eyes of insects and the nearly crystalline photoreceptor patterns of some fish and reptiles. Birds are highly visual animals with five different cone photoreceptor subtypes, yet their photoreceptor patterns are not perfectly regular. By analyzing the chicken cone photoreceptor system consisting of five different cell types using a variety of sensitive microstructural descriptors, we find that the disordered photoreceptor patterns are "hyperuniform" (exhibiting vanishing infinite-wavelength density fluctuations), a property that had heretofore been identified in a unique subset of physical systems, but had never been observed in any living organism. Remarkably, the patterns of both the total population and the individual cell types are simultaneously hyperuniform. We term such patterns "multihyperuniform" because multiple distinct subsets of the overall point pattern are themselves hyperuniform. We have devised a unique multiscale cell packing model in two dimensions that suggests that photoreceptor types interact with both short- and long-ranged repulsive forces and that the resultant competition between the types gives rise to the aforementioned singular spatial features characterizing the system, including multihyperuniformity. These findings suggest that a disordered hyperuniform pattern may represent the most uniform sampling arrangement attainable in the avian system, given intrinsic packing constraints within the photoreceptor epithelium. In addition, they show how fundamental physical constraints can change the course of a biological optimization process. Our results suggest that multihyperuniform disordered structures have implications for the design of materials with novel physical properties and therefore may represent a fruitful area for future research.

Role of magnetic and diamagnetic interactions in molecular optics and scattering

NASA Astrophysics Data System (ADS)

Forbes, Kayn A.

2018-05-01

This paper aims to explicitly clarify the role and interpretation of diamagnetic interactions between molecules and light in quantum electrodynamics. In contrast to their electric and magnetic counterparts, the diamagnetic couplings between light and matter have received relatively little interest in the field of molecular optics. This intriguing disregard of an interaction term is puzzling. The diamagnetic couplings possess unique physical properties that warrant their inclusion in any multiphoton process, and the lack of gauge invariance for paramagnetic and diamagnetic susceptibilities necessitates their inclusion. Their role and importance within nonrelativistic molecular quantum electrodynamics in the Coulomb gauge is illuminated, and it is highlighted how for any multiphoton process their inclusion should be implicit. As an indicative example of the theory presented, the diamagnetic contributions to both forward and nonforward Rayleigh scattering are derived and put into context alongside the electric and magnetic molecular responses. The work represents clarification of diamagnetic couplings in molecular quantum electrodynamics, which subsequently should proffer the study of diamagnetic interactions in molecular optics due to their unique physical attributes and necessary inclusion in multiphoton processes.

30 years of cosmic fullerenes

NASA Astrophysics Data System (ADS)

Berné, O.; Montillaud, J.; Mulas, G.; Joblin, C.

2015-12-01

In 1985, ``During experiments aimed at understanding the mechanisms by which long-chain carbon molecules are formed in interstellar space and circumstellar shells'', Harry Kroto and his collaborators serendipitously discovered a new form of carbon: fullerenes. The most emblematic fullerene (i.e. C_{60} ``buckminsterfullerene''), contains exactly 60 carbon atoms organized in a cage-like structure similar to a soccer ball. Since their discovery impacted the field of nanotechnologies, Kroto and colleagues received the Nobel prize in 1996. The cage-like structure, common to all fullerene molecules, gives them unique properties, in particular an extraordinary stability. For this reason and since they were discovered in experiments aimed to reproduce conditions in space, fullerenes were sought after by astronomers for over two decades, and it is only recently that they have been firmly identified by spectroscopy, in evolved stars and in the interstellar medium. This identification offered the opportunity to study the molecular physics of fullerenes in the unique physical conditions provided by space, and to make the link with other large carbonaceous molecules thought to be present in space : polycyclic aromatic hydrocarbons.

Self-Healing Behavior of Ethylene-Based Ionomers

NASA Technical Reports Server (NTRS)

Kalista, Stephen J., Jr.; Ward, Thomas C.; Oyetunji, Zainab

2004-01-01

The self-healing behavior of poly(ethylene-co-methacrylic acid) (EMAA)-based ionomers holds tremendous potential for use in a wide variety of unique applications. However, to effectively utilize this self-healing behavior and to design novel materials which possess this ability, the mechanism by which they heal must first be understood ionomers are a class of polymers that can be described as copolymers containing less than 15 mol% ionic content whereby the bulk properties are governed by ionic interactions within the polymer. These ionic groups aggregate into discrete regions known as multiplets which overlap forming clusters that act as physical cross-links profoundly influencing the bulk physical properties. These clusters possess an order-disorder transition (T(sub i)) where the clustered regions may rearrange themselves given time and stimuli. Recognizing the strong influence of these ionic regions on other well understood ionomer properties, their role in self-heating behavior will be assessed. The self-healing behavior is observed following projectile puncture. It has been suggested that during impact energy is passed to the ionomer material, heating it to the melt state. After penetration, it is proposed that the ionic regions maintain their attractions and flow together patching the hole. Thus, the importance of this ionic character and is unique interaction must be established. This will be accomplished through examination of materials with varying ionic content and through the analysis of the T(sub i). The specific ionomer systems examined include a number of ethylene-based materials. Materials of varying ionic content, including the non-ionic base copolymers, will be examined by peel tests, projectile impact and DSC analysis. The information will also be compared with some basic data on LDPE material.

New Strategies in Radiation Therapy: Exploiting the Full Potential of Protons

PubMed Central

Mohan, Radhe; Mahajan, Anita; Minsky, Bruce D.

2013-01-01

Protons provide significant dosimetric advantages compared with photons due to their unique depth-dose distribution characteristics. However, they are more sensitive to the effects of intra- and inter-treatment fraction anatomic variations and uncertainties in treatment setup. Furthermore, in the current practice of proton therapy, the biological effectiveness of protons relative to photons is assumed to have a generic fixed value of 1.1. However, this is a simplification, and it is likely higher in different portions of the proton beam. Current clinical practice and trials have not fully exploited the unique physical and biological properties of protons. Intensity-modulated proton therapy, with its ability to manipulate energies (in addition to intensities), provides an entirely new dimension, which, with ongoing research, has considerable potential to increase the therapeutic ratio. PMID:24077353

New strategies in radiation therapy: exploiting the full potential of protons.

PubMed

Mohan, Radhe; Mahajan, Anita; Minsky, Bruce D

2013-12-01

Protons provide significant dosimetric advantages compared with photons because of their unique depth-dose distribution characteristics. However, they are more sensitive to the effects of intra- and intertreatment fraction anatomic variations and uncertainties in treatment setup. Furthermore, in the current practice of proton therapy, the biologic effectiveness of protons relative to photons is assumed to have a generic fixed value of 1.1. However, this is a simplification, and it is likely higher in different portions of the proton beam. Current clinical practice and trials have not fully exploited the unique physical and biologic properties of protons. Intensity-modulated proton therapy, with its ability to manipulate energies (in addition to intensities), provides an entirely new dimension, which, with ongoing research, has considerable potential to increase the therapeutic ratio. ©2013 AACR.

Constraining the physical properties of compositionally distinctive surfaces on Mars from overlapping THEMIS observations

NASA Astrophysics Data System (ADS)

Ahern, A.; Rogers, D.

2017-12-01

Better constraints on the physical properties (e.g. grain size, rock abundance, cohesion, porosity and amount of induration) of Martian surface materials can lead to greater understanding of outcrop origin (e.g. via sedimentary, effusive volcanic, pyroclastic processes). Many outcrop surfaces on Mars likely contain near-surface (<3 cm) vertical heterogeneity in physical properties due to thin sediment cover, induration, and physical weathering, that can obscure measurement of the bulk thermal conductivity of the outcrop materials just below. Fortunately, vertical heterogeneity within near-surface materials can result in unique, and possibly predictable, diurnal and seasonal temperature patterns. The KRC thermal model has been utilized in a number of previous studies to predict thermal inertia of surface materials on Mars. Here we use KRC to model surface temperatures from overlapping Mars Odyssey THEMIS surface temperature observations that span multiple seasons and local times, in order to constrain both the nature of vertical heterogeneity and the underlying outcrop thermal inertia for various spectrally distinctive outcrops on Mars. We utilize spectral observations from TES and CRISM to constrain the particle size of the uppermost surface. For this presentation, we will focus specifically on chloride-bearing units in Terra Sirenum and Meridiani Planum, as well as mafic and feldspathic bedrock locations with distinct spectral properties, yet uncertain origins, in Noachis Terra and Nili Fossae. We find that many of these surfaces exhibit variations in apparent thermal inertia with season and local time that are consistent with low thermal inertia materials overlying higher thermal inertia substrates. Work is ongoing to compare surface temperature measurements with modeled two-layer scenarios in order to constrain the top layer thickness and bottom layer thermal inertia. The information will be used to better interpret the origins of these distinctive outcrops.

The Miniature Radio Frequency Instruments (Mini-RF) Global Observations of Earth's Moon

NASA Technical Reports Server (NTRS)

Cahill, Joshua T. S.; Thomson, B. J.; Patterson, G. Wesley; Bussey, D. Benjamin J.; Neish, Catherine D.; Lopez, Norberto R.; Turner, F. Scott; Aldridge, T.; McAdam, M.; Meyer, H. M.;

Adsorption of divalent metals to metal oxide nanoparicles: Competitive and temperature effects

NASA Astrophysics Data System (ADS)

Grover, Valerie Ann

The presence of metals in natural waters is becoming a critical environmental and public health concern. Emerging nanotechnology and the use of metal oxide nanoparticles has been identified as a potential remediation technique in removing metals from water. However, practical applications are still being explored to determine how to apply their unique chemical and physical properties for full scale remediation projects. This thesis investigates the sorption properties of Cd(II), Cu(II), Pb(II) and Zn(II) to hematite (alpha-Fe2O3) and titanium dioxide (TiO2) nanoparticles in single- and binary-adsorbate systems. Competitive sorption was evaluated in 1L batch binary-metal systems with 0.05g/L nano-hematite at pH 8.0 and pH 6.0. Results indicate that the presence of a secondary metal can affect the sorption process depending upon the molar ratios, such as increased or reduced adsorption. Thermodynamic properties were also studied in order to better understand the effects of temperature on equilibrium and kinetic adsorption capabilities. Understanding the thermodynamic properties can also give insight to determine if the sorption process is a physical, chemical or ion exchange reaction. Thermodynamic parameters such as enthalpy (DeltaH), entropy (DeltaS), and Gibbs free energy (DeltaG) were evaluated as a function of temperature, pH, and metal concentration. Results indicate that Pb(II) and Cu(II) adsorption to nano-hematite was an endothermic and physical adsorption process, while Zn(II) and Cd(II) adsorption was dependent upon the adsorbed concentration evaluated. However, metal adsorptions to nano-titanium dioxide were all found to be endothermic and physical adsorption processes; the spontaneity of metal adsorption was temperature dependent for both metal oxide nanoparticles.

Atomic scale imaging of magnetic circular dichroism by achromatic electron microscopy.

PubMed

Wang, Zechao; Tavabi, Amir H; Jin, Lei; Rusz, Ján; Tyutyunnikov, Dmitry; Jiang, Hanbo; Moritomo, Yutaka; Mayer, Joachim; Dunin-Borkowski, Rafal E; Yu, Rong; Zhu, Jing; Zhong, Xiaoyan

2018-03-01

In order to obtain a fundamental understanding of the interplay between charge, spin, orbital and lattice degrees of freedom in magnetic materials and to predict and control their physical properties 1-3 , experimental techniques are required that are capable of accessing local magnetic information with atomic-scale spatial resolution. Here, we show that a combination of electron energy-loss magnetic chiral dichroism 4 and chromatic-aberration-corrected transmission electron microscopy, which reduces the focal spread of inelastically scattered electrons by orders of magnitude when compared with the use of spherical aberration correction alone, can achieve atomic-scale imaging of magnetic circular dichroism and provide element-selective orbital and spin magnetic moments atomic plane by atomic plane. This unique capability, which we demonstrate for Sr 2 FeMoO 6 , opens the door to local atomic-level studies of spin configurations in a multitude of materials that exhibit different types of magnetic coupling, thereby contributing to a detailed understanding of the physical origins of magnetic properties of materials at the highest spatial resolution.

Manipulating type-I and type-II Dirac polaritons in cavity-embedded honeycomb metasurfaces.

PubMed

Mann, Charlie-Ray; Sturges, Thomas J; Weick, Guillaume; Barnes, William L; Mariani, Eros

2018-06-06

Pseudorelativistic Dirac quasiparticles have emerged in a plethora of artificial graphene systems that mimic the underlying honeycomb symmetry of graphene. However, it is notoriously difficult to manipulate their properties without modifying the lattice structure. Here we theoretically investigate polaritons supported by honeycomb metasurfaces and, despite the trivial nature of the resonant elements, we unveil rich Dirac physics stemming from a non-trivial winding in the light-matter interaction. The metasurfaces simultaneously exhibit two distinct species of massless Dirac polaritons, namely type-I and type-II. By modifying only the photonic environment via an enclosing cavity, one can manipulate the location of the type-II Dirac points, leading to qualitatively different polariton phases. This enables one to alter the fundamental properties of the emergent Dirac polaritons while preserving the lattice structure-a unique scenario which has no analog in real or artificial graphene systems. Exploiting the photonic environment will thus give rise to unexplored Dirac physics at the subwavelength scale.

Synthesis and characterization of conducting polyaniline-copper composites.

PubMed

Liu, Aijie; Bac, Luong Huu; Kim, Ji-Soon; Kim, Byoung-Kee; Kim, Jin-Chun

2013-11-01

Conducting polymer composites have many interesting physical properties and important application potentials. Suitable combinations of metal nanoparticles with conductive polymers can result in composite materials having unique physical and chemical properties that can have wide application potential in diverse areas. In this work, copper nanoparticles were fabricated by electrical explosion of wire (EEW) in solution of polyacrylic acid (PAA) and ethanol. Conductive polyaniline-copper (PANI-Cu) composites have been synthesized by in-situ polymerization of aniline in the fabricated copper suspension. Optical absorption in the UV-visible region of these suspensions was measured in the range of 200-900 nm. Morphology and structure of the composites were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier-transform infrared spectra (FTIR). Pure copper nanoparticles were uniformly dispersed into the polymer matrix. Thermal stability of the composites was characterized by thermogravimetric analysis (TGA). Electrical conductivity measurements indicated that the conductivity of the composites was higher than that of pure polyaniline and increased with increasing content of copper.

Soda pans of the Pannonian steppe harbor unique bacterial communities adapted to multiple extreme conditions.

PubMed

Szabó, Attila; Korponai, Kristóf; Kerepesi, Csaba; Somogyi, Boglárka; Vörös, Lajos; Bartha, Dániel; Márialigeti, Károly; Felföldi, Tamás

2017-05-01

Soda pans of the Pannonian steppe are unique environments regarding their physical and chemical characteristics: shallowness, high turbidity, intermittent character, alkaline pH, polyhumic organic carbon concentration, hypertrophic condition, moderately high salinity, sodium and carbonate ion dominance. The pans are highly productive environments with picophytoplankton predominance. Little is known about the planktonic bacterial communities inhabiting these aquatic habitats; therefore, amplicon sequencing and shotgun metagenomics were applied to reveal their composition and functional properties. Results showed a taxonomically complex bacterial community which was distinct from other soda lakes regarding its composition, e.g. the dominance of class Alphaproteobacteria was observed within phylum Proteobacteria. The shotgun metagenomic analysis revealed several functional gene components related to the harsh and at the same time hypertrophic environmental conditions, e.g. proteins involved in stress response, transport and hydrolase systems targeting phytoplankton-derived organic matter. This is the first detailed report on the indigenous planktonic bacterial communities coping with the multiple extreme conditions present in the unique soda pans of the Pannonian steppe.

Zero refractive index in time-Floquet acoustic metamaterials

NASA Astrophysics Data System (ADS)

Koutserimpas, Theodoros T.; Fleury, Romain

2018-03-01

New scientific investigations of artificially structured materials and experiments have exhibited wave manipulation to the extreme. In particular, zero refractive index metamaterials have been on the front line of wave physics research for their unique wave manipulation properties and application potentials. Remarkably, in such exotic materials, time-harmonic fields have an infinite wavelength and do not exhibit any spatial variations in their phase distribution. This unique feature can be achieved by forcing a Dirac cone to the center of the Brillouin zone ( Γ point), as previously predicted and experimentally demonstrated in time-invariant metamaterials by means of accidental degeneracy between three different modes. In this article, we propose a different approach that enables true conical dispersion at Γ with twofold degeneracy and generates zero index properties. We break time-reversal symmetry and exploit a time-Floquet modulation scheme to demonstrate a time-Floquet acoustic metamaterial with zero refractive index. This behavior, predicted using stroboscopic analysis, is confirmed by full-wave finite element simulations. Our results establish the relevance of time-Floquet metamaterials as a novel reconfigurable platform for wave control.

MOF-5-Polystyrene: Direct Production from Monomer, Improved Hydrolytic Stability, and Unique Guest Adsorption.

PubMed

Gamage, Nipuni-Dhanesha H; McDonald, Kyle A; Matzger, Adam J

2016-09-19

An unprecedented mode of reactivity of Zn4 O-based metal-organic frameworks (MOFs) offers a straightforward and powerful approach to polymer-hybridized porous solids. The concept is illustrated with the production of MOF-5-polystyrene wherein polystyrene is grafted and uniformly distributed throughout MOF-5 crystals after heating in pure styrene for 4-24 h. The surface area and polystyrene content of the material can be fine-tuned by controlling the duration of heating styrene in the presence of MOF-5. Polystyrene grafting significantly alters the physical and chemical properties of pristine MOF-5, which is evident from the unique guest adsorption properties (solvatochromic dye uptake and improved CO2 capacity) as well as the dramatically improved hydrolytic stability of composite. Based on the fact that MOF-5 is the best studied member of the structure class, and has been produced at scale by industry, these findings can be directly leveraged for a range of current applications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Possible Operational Motivation for the Orthocomplementation in Quantum Structures

NASA Astrophysics Data System (ADS)

D'Hooghe, Bart

2010-11-01

In the foundations of quantum mechanics Gleason’s theorem dictates the uniqueness of the state transition probability via the inner product of the corresponding state vectors in Hilbert space, independent of which measurement context induces this transition. We argue that the state transition probability should not be regarded as a secondary concept which can be derived from the structure on the set of states and properties, but instead should be regarded as a primitive concept for which measurement context is crucial. Accordingly, we adopt an operational approach to quantum mechanics in which a physical entity is defined by the structure of its set of states, set of properties and the possible (measurement) contexts which can be applied to this entity. We put forward some elementary definitions to derive an operational theory from this State-COntext-Property (SCOP) formalism. We show that if the SCOP satisfies a Gleason-like condition, namely that the state transition probability is independent of which measurement context induces the change of state, then the lattice of properties is orthocomplemented, which is one of the ‘quantum axioms’ used in the Piron-Solèr representation theorem for quantum systems. In this sense we obtain a possible physical meaning for the orthocomplementation widely used in quantum structures.

The Blood–Brain Barrier

PubMed Central

Daneman, Richard; Prat, Alexandre

2015-01-01

Blood vessels are critical to deliver oxygen and nutrients to all of the tissues and organs throughout the body. The blood vessels that vascularize the central nervous system (CNS) possess unique properties, termed the blood–brain barrier, which allow these vessels to tightly regulate the movement of ions, molecules, and cells between the blood and the brain. This precise control of CNS homeostasis allows for proper neuronal function and also protects the neural tissue from toxins and pathogens, and alterations of these barrier properties are an important component of pathology and progression of different neurological diseases. The physiological barrier is coordinated by a series of physical, transport, and metabolic properties possessed by the endothelial cells (ECs) that form the walls of the blood vessels, and these properties are regulated by interactions with different vascular, immune, and neural cells. Understanding how these different cell populations interact to regulate the barrier properties is essential for understanding how the brain functions during health and disease. PMID:25561720

Electromagnetic sinc Schell-model beams and their statistical properties.

PubMed

Mei, Zhangrong; Mao, Yonghua

2014-09-22

A class of electromagnetic sources with sinc Schell-model correlations is introduced. The conditions on source parameters guaranteeing that the source generates a physical beam are derived. The evolution behaviors of statistical properties for the electromagnetic stochastic beams generated by this new source on propagating in free space and in atmosphere turbulence are investigated with the help of the weighted superposition method and by numerical simulations. It is demonstrated that the intensity distributions of such beams exhibit unique features on propagating in free space and produce a double-layer flat-top profile of being shape-invariant in the far field. This feature makes this new beam particularly suitable for some special laser processing applications. The influences of the atmosphere turbulence with a non-Kolmogorov power spectrum on statistical properties of the new beams are analyzed in detail.

From astrophysics to mesoscopic physics: a sightseeing tour in the world of clusters and fullerenes

NASA Astrophysics Data System (ADS)

Rosen, Arne; Ostling, Daniel; Apell, P.; Tomanek, D.

1996-12-01

The discovery of the fullerenes in 1985 by Kroto, Heath, O'Brien, Curl and Smalley and the development of a method for production of macroscopic amounts in 1990 by Kraetschmer, Lamb, Fostiropoulos and Huffman opened a new area of carbon research with possible production of new materials with unique properties. The field has developed further later on with discoveries of nanotubes, metal filled nanotubes, carbon onions and more recently metal covered fullerenes. All these new discoveries show how cluster science opens approaches to the area of meososcopic physics. The general trend is here in the direction from small to large contrary to the general trend of modern meososcopic physics or micro-electronics where the movement is from large to small. It is especially fascinating how the whole area of fullerene research was initiated by problems in astrophysics. Originally Kraetschmer and Huffman had the intention to explain an observed strong extinction form interstellar dust and produced in experiments special carbon soot with a characteristics optical absorption known as 'the camel hump smoke'. This paper gives a short overview of some of our more recent theoretical work of the electronic properties of C60, metal covered C60 and nanotubes. In addition some results are also presented of optical properties of metal covered C60 as a function of metal coverage.

Chiral Superstructure Mesophases of Achiral Bent-Shaped Molecules - Hierarchical Chirality Amplification and Physical Properties.

PubMed

Le, Khoa V; Takezoe, Hideo; Araoka, Fumito

2017-07-01

Chiral mesophases in achiral bent-shaped molecules have attracted particular attention since their discovery in the middle 1990s, not only because of their homochirality and polarity, but also due to their unique physical/physicochemical properties. Here, the most intriguing results in the studies of such symmetry-broken states, mainly helical-nanofilament (HNF) and dark-conglomerate (DC) phases, are reviewed. Firstly, basic information on the typical appearance and optical activity in these phases is introduced. In the following section, the formation of mesoscopic chiral superstructures in the HNF and DC phases is discussed in terms of hierarchical chirality. Nanoscale phase segregation in mixture systems and gelation ability in the HNF phase are also described. In addition, some other related chiral phases of bent-shaped molecules are shown. Recent attempts to control such mesoscopic chiral structure and the alignment/confinement of HNFs are also discussed, along with several examples of their fascinating advanced physical properties, i.e. huge enhancement of circular dichroism, electro- and photo-tunable optical activities, chirality-induced nonlinear optics (second-harmonic-generation circular difference and electrogyration effect), enhanced hydrophobicity through the dual-scale surface morphological modulation, and photoconductivity in the HNF/fullerene binary system. Future prospects from basic science and application viewpoints are also indicated in the concluding section. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Structure of peat soils and implications for biogeochemical processes and hydrological flow

NASA Astrophysics Data System (ADS)

Rezanezhad, F.; McCarter, C. P. R.; Gharedaghloo, B.; Kleimeier, C.; Milojevic, T.; Liu, H.; Weber, T. K. D.; Price, J. S.; Quinton, W. L.; Lenartz, B.; Van Cappellen, P.

2017-12-01

Permafrost peatlands contain globally important amounts of soil organic carbon and play major roles in global water, nutrient and biogeochemical cycles. The structure of peatland soils (i.e., peat) are highly complex with unique physical and hydraulic properties; where significant, and only partially reversible, shrinkage occurs during dewatering (including water table fluctuations), compression and/or decomposition. These distinct physical and hydraulic properties controls water flow, which in turn affect reactive and non-reactive solute transport (such as, sorption or degradation) and biogeochemical functions. Additionally, peat further attenuates solute migration through molecular diffusion into the inactive pores of Sphagnum dominated peat. These slow, diffusion-limited solute exchanges between the pore regions may give rise to pore-scale chemical gradients and heterogeneous distributions of microbial habitats and activity in peat soils. Permafrost peat plateaus have the same essential subsurface characteristics as other widely organic soil-covered peatlands, where the hydraulic conductivity is related to the degree of decomposition and soil compression. Increasing levels of decomposition correspond with a reduction of effective pore diameter and consequently restrict water and solute flow (by several orders of magnitude in hydraulic conductivity between the ground surface and a depth of 50 cm). In this presentation, we present the current knowledge of key physical and hydraulic properties related to the structure of globally available peat soils and discuss their implications for water storage, flow and the migration of solutes.

Device-independent point estimation from finite data and its application to device-independent property estimation

NASA Astrophysics Data System (ADS)

Lin, Pei-Sheng; Rosset, Denis; Zhang, Yanbao; Bancal, Jean-Daniel; Liang, Yeong-Cherng

2018-03-01

The device-independent approach to physics is one where conclusions are drawn directly from the observed correlations between measurement outcomes. In quantum information, this approach allows one to make strong statements about the properties of the underlying systems or devices solely via the observation of Bell-inequality-violating correlations. However, since one can only perform a finite number of experimental trials, statistical fluctuations necessarily accompany any estimation of these correlations. Consequently, an important gap remains between the many theoretical tools developed for the asymptotic scenario and the experimentally obtained raw data. In particular, a physical and concurrently practical way to estimate the underlying quantum distribution has so far remained elusive. Here, we show that the natural analogs of the maximum-likelihood estimation technique and the least-square-error estimation technique in the device-independent context result in point estimates of the true distribution that are physical, unique, computationally tractable, and consistent. They thus serve as sound algorithmic tools allowing one to bridge the aforementioned gap. As an application, we demonstrate how such estimates of the underlying quantum distribution can be used to provide, in certain cases, trustworthy estimates of the amount of entanglement present in the measured system. In stark contrast to existing approaches to device-independent parameter estimations, our estimation does not require the prior knowledge of any Bell inequality tailored for the specific property and the specific distribution of interest.

Which forms of child/adolescent externalizing behaviors account for late adolescent risky sexual behavior and substance use?

PubMed

Timmermans, Maartje; van Lier, Pol A C; Koot, Hans M

2008-04-01

Health risk behaviors like substance use (alcohol, tobacco, soft/hard drugs) and risky sexual behavior become more prevalent in adolescence. Children with behavior problems are thought to be prone to engage in health risk behaviors later in life. It is, however, unclear which problems within the externalizing spectrum account for these outcomes. Three hundred and nine children were followed from age 4/5 years to 18 years (14-year follow-up). Level and course of parent-rated opposition, physical aggression, status violations and property violations were used to predict adolescent-reported substance use and risky sexual behavior at age 18 years. Both level and change in physical aggression were unique predictors of all forms of adolescent health risk behavior. Levels of status violations predicted smoking and soft drug use only, while change in property violations predicted each of the health risk behaviors. The links between opposition and health risk behaviors were accounted for by co-occurring problem behaviors. Of externalizing problems, physical aggression is the best predictor of adolescent substance use and risky sexual behavior from childhood onwards. Possible explanations and implications of these findings, and future research directions are discussed.

Challenges in Physical Characterization of Dim Space Objects: What Can We Learn from NEOs

NASA Astrophysics Data System (ADS)

Reddy, V.; Sanchez, J.; Thirouin, A.; Rivera-Valentin, E.; Ryan, W.; Ryan, E.; Mokovitz, N.; Tegler, S.

2016-09-01

Physical characterization of dim space objects in cis-lunar space can be a challenging task. Of particular interest to both natural and artificial space object behavior scientists are the properties beyond orbital parameters that can uniquely identify them. These properties include rotational state, size, shape, density and composition. A wide range of observational and non-observational factors affect our ability to characterize dim objects in cis-lunar space. For example, phase angle (angle between Sun-Target-Observer), temperature, rotational variations, temperature, and particle size (for natural dim objects). Over the last two decades, space object behavior scientists studying natural dim objects have attempted to quantify and correct for a majority of these factors to enhance our situational awareness. These efforts have been primarily focused on developing laboratory spectral calibrations in a space-like environment. Calibrations developed correcting spectral observations of natural dim objects could be applied to characterizing artificial objects, as the underlying physics is the same. The paper will summarize our current understanding of these observational and non-observational factors and present a case study showcasing the state of the art in characterization of natural dim objects.

Inorganic and methane clathrates: Versatility of guest–host compounds for energy harvesting

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

Krishna, Lakshmi; Koh, Carolyn A.

ABSTRACT This review article evaluates the structure–property relations of inorganic clathrates and clathrate hydrates and their potential role in energy harvesting. There is potential cross-fertilization between the two research areas. Guest–host clathrate compounds exhibit unique structural and physical properties, which lead to their versatile roles in energy applications. Prominent classes of clathrate compounds are gas hydrates and inorganic clathrates. That said, there is limited cross-fertilization between the clathrate hydrate and inorganic clathrate communities, with researchers in the respective fields being less informed on the other field. Yet the structures and unique guest–host interactions in both these compounds are common importantmore » features of these clathrates. Common features and procedures can inspire and inform development between the compound classes, which may be important to the technological advancements for the different clathrate materials, e.g., structure characterization techniques and guest–host dynamics in which the “guest” tends to be imprisoned in the host structure, until external forces are applied. Conversely, the diversity in chemical compositions of these two classes of materials leads to the different applications from methane capture and storage to converting waste heat to electricity (thermoelectrics). This article highlights the structural and physical similarities and differences of inorganic and methane clathrates. The most promising state-of-the-art applications of the clathrates are highlighted for harvesting energy from methane (clathrate) hydrate deposits under the ocean and for inorganic clathrates as promising thermoelectric materials.« less

Inorganic and methane clathrates: Versatility of guest–host compounds for energy harvesting

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

Krishna, Lakshmi; Koh, Carolyn A.

2015-01-01

ABSTRACT This review article evaluates the structure–property relations of inorganic clathrates and clathrate hydrates and their potential role in energy harvesting. There is potential cross-fertilization between the two research areas. Guest–host clathrate compounds exhibit unique structural and physical properties, which lead to their versatile roles in energy applications. Prominent classes of clathrate compounds are gas hydrates and inorganic clathrates. That said, there is limited cross-fertilization between the clathrate hydrate and inorganic clathrate communities, with researchers in the respective fields being less informed on the other field. Yet the structures and unique guest–host interactions in both these compounds are common importantmore » features of these clathrates. Common features and procedures can inspire and inform development between the compound classes, which may be important to the technological advancements for the different clathrate materials, e.g., structure characterization techniques and guest–host dynamics in which the “guest” tends to be imprisoned in the host structure, until external forces are applied. Conversely, the diversity in chemical compositions of these two classes of materials leads to the different applications from methane capture and storage to converting waste heat to electricity (thermoelectrics). This article highlights the structural and physical similarities and differences of inorganic and methane clathrates. The most promising state-of-the-art applications of the clathrates are highlighted for harvesting energy from methane (clathrate) hydrate deposits under the ocean and for inorganic clathrates as promising thermoelectric materials.« less

RNA as a stable polymer to build controllable and defined nanostructures for material and biomedical applications

PubMed Central

Li, Hui; Lee, Taek; Dziubla, Thomas; Pi, Fengmei; Guo, Sijin; Xu, Jing; Li, Chan; Haque, Farzin; Liang, Xing-Jie; Guo, Peixuan

2015-01-01

Summary The value of polymers is manifested in their vital use as building blocks in material and life sciences. Ribonucleic acid (RNA) is a polynucleic acid, but its polymeric nature in materials and technological applications is often overlooked due to an impression that RNA is seemingly unstable. Recent findings that certain modifications can make RNA resistant to RNase degradation while retaining its authentic folding property and biological function, and the discovery of ultra-thermostable RNA motifs have adequately addressed the concerns of RNA unstability. RNA can serve as a unique polymeric material to build varieties of nanostructures including nanoparticles, polygons, arrays, bundles, membrane, and microsponges that have potential applications in biomedical and material sciences. Since 2005, more than a thousand publications on RNA nanostructures have been published in diverse fields, indicating a remarkable increase of interest in the emerging field of RNA nanotechnology. In this review, we aim to: delineate the physical and chemical properties of polymers that can be applied to RNA; introduce the unique properties of RNA as a polymer; review the current methods for the construction of RNA nanostructures; describe its applications in material, biomedical and computer sciences; and, discuss the challenges and future prospects in this field. PMID:26770259

A review on the synthesis, crystal growth, structure and physical properties of rare earth based quaternary intermetallic compounds

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

Mumbaraddi, Dundappa; Sarkar, Sumanta; Peter, Sebastian C., E-mail: sebastiancp@jncasr.ac.in

2016-04-15

This review highlights the synthesis and crystal growth of quaternary intermetallic compounds based on rare earth metals. In the first part of this review, we highlight briefly about intermetallics and their versatile properties in comparison to the constituent elements. In the next part, we have discussed about various synthesis techniques with more focus on the metal flux technique towards the well shaped crystal growth of novel compounds. In the subsequent parts, several disordered quaternary compounds have been reviewed and then outlined most known ordered quaternary compounds with their complex structure. A special attention has been given to the ordered compoundsmore » with structural description and relation to the parent binary and ternary compounds. The importance of electronic and structural feature is highlighted as the key roles in designing these materials for emerging applications. - Graphical abstract: Rare earth based quaternary intermetallic compounds crystallize in complex novel crystal structures. The diversity in the crystal structure may induce unique properties and can be considered them as future materials. - Highlights: • Crystal growth and crystal structure of quaternary rare earth based intermetallics. • Structural complexity of quaternary compounds in comparison to the parent compounds. • Novel quaternary compounds display unique crystal structure.« less

Characterization of maximally random jammed sphere packings. III. Transport and electromagnetic properties via correlation functions

NASA Astrophysics Data System (ADS)

Klatt, Michael A.; Torquato, Salvatore

2018-01-01

In the first two papers of this series, we characterized the structure of maximally random jammed (MRJ) sphere packings across length scales by computing a variety of different correlation functions, spectral functions, hole probabilities, and local density fluctuations. From the remarkable structural features of the MRJ packings, especially its disordered hyperuniformity, exceptional physical properties can be expected. Here we employ these structural descriptors to estimate effective transport and electromagnetic properties via rigorous bounds, exact expansions, and accurate analytical approximation formulas. These property formulas include interfacial bounds as well as universal scaling laws for the mean survival time and the fluid permeability. We also estimate the principal relaxation time associated with Brownian motion among perfectly absorbing traps. For the propagation of electromagnetic waves in the long-wavelength limit, we show that a dispersion of dielectric MRJ spheres within a matrix of another dielectric material forms, to a very good approximation, a dissipationless disordered and isotropic two-phase medium for any phase dielectric contrast ratio. We compare the effective properties of the MRJ sphere packings to those of overlapping spheres, equilibrium hard-sphere packings, and lattices of hard spheres. Moreover, we generalize results to micro- and macroscopically anisotropic packings of spheroids with tensorial effective properties. The analytic bounds predict the qualitative trend in the physical properties associated with these structures, which provides guidance to more time-consuming simulations and experiments. They especially provide impetus for experiments to design materials with unique bulk properties resulting from hyperuniformity, including structural-color and color-sensing applications.

Fabrication of graphene oxide-modified chitosan for controlled release of dexamethasone phosphate

NASA Astrophysics Data System (ADS)

Sun, Huanghui; Zhang, Lingfan; Xia, Wei; Chen, Linxiao; Xu, Zhizhen; Zhang, Wenqing

2016-07-01

Functionalized graphene oxide with its unique physical and chemical properties is widely applied in biomaterials, especially in drug carrier materials. In the past few years, a number of different drugs have been loaded on functionalized graphene oxide via π-π stacking and hydrophobic interactions. The present report described a new approach, dexamethasone phosphate successfully loaded onto graphene oxide-chitosan nanocomposites as drug carrier materials by covalent bonding of phosphate ester linkage. Compared with the graphene oxide-chitosan nanocomposites that dexamethasone phosphate was loaded on via simple physical attachment, covalently linked composites as drug carrier materials were more biocompatible which effectively reduced the burst release of drug, and controlled the release of drug in different pH conditions.

Open Solar Physics Questions - What Can Orbiter Do That Could Not Be Addressed By Existing Missions?

NASA Technical Reports Server (NTRS)

Antiochos, S. K.

2009-01-01

Solar Orbiter represents a revolutionary advance in observing the Sun. Orbiter will have optical and XUV telescopes that will deliver high-resolution images and spectra from vantages points that have never been possible before, dose to the Sun and at high latitudes. At the same time, Orbiter will measure in situ the properties of the solar wind that originate from the observed solar photosphere and corona. In this presentation, Ivvi|/ describe how with its unique vantage points and capabilities, Orbiter will allow us to answer, for the first time, some of the major question in solar physics, such as: Where does the slow wind originate? How do CMEs initiate and evolve? What is the heating mechanism in corona/ loops.

The Chandra Strong Lens Sample: Revealing Baryonic Physics In Strong Lensing Selected Clusters

NASA Astrophysics Data System (ADS)

Bayliss, Matthew

2017-08-01

We propose for Chandra imaging of the hot intra-cluster gas in a unique new sample of 29 galaxy clusters selected purely on their strong gravitational lensing signatures. This will be the first program targeting a purely strong lensing selected cluster sample, enabling new comparisons between the ICM properties and scaling relations of strong lensing and mass/ICM selected cluster samples. Chandra imaging, combined with high precision strong lens models, ensures powerful constraints on the distribution and state of matter in the cluster cores. This represents a novel angle from which we can address the role played by baryonic physics |*| the infamous |*|gastrophysics|*| in shaping the cores of massive clusters, and opens up an exciting new galaxy cluster discovery space with Chandra.

The Chandra Strong Lens Sample: Revealing Baryonic Physics In Strong Lensing Selected Clusters

NASA Astrophysics Data System (ADS)

Bayliss, Matthew

2017-09-01

We propose for Chandra imaging of the hot intra-cluster gas in a unique new sample of 29 galaxy clusters selected purely on their strong gravitational lensing signatures. This will be the first program targeting a purely strong lensing selected cluster sample, enabling new comparisons between the ICM properties and scaling relations of strong lensing and mass/ICM selected cluster samples. Chandra imaging, combined with high precision strong lens models, ensures powerful constraints on the distribution and state of matter in the cluster cores. This represents a novel angle from which we can address the role played by baryonic physics -- the infamous ``gastrophysics''-- in shaping the cores of massive clusters, and opens up an exciting new galaxy cluster discovery space with Chandra.

Physical property control in core/shell inorganic nanostructures for fluorescence and magnetic targeting applications

NASA Astrophysics Data System (ADS)

Roberts, Stephen K.

Nanomaterials show immense promise for the future in numerous areas of application. Properties that are unique from the bulk material and are tunable allow for innovation in material design. This thesis will focus on controlling the physical properties of core/shell nanostructures to enhance the utility of the materials. The first focus is on the impact of different solvent mixtures during the shell growth phase of SILAR based core/shell quantum dot synthesis is studied. Gaining insight into the mechanism for SILAR growth of core/shell nanoparticles allows improved synthetic yields and precursor binding, providing enhanced control to synthesis of core/shell nanoparticles. The second focus of this thesis is exploring the use of magnetic nanoparticles for magnetic drug targeting for cardiovascular conditions. Magnetic targeting for drug delivery enables increased local drug concentration, while minimizing non-specific interactions. In order to be effective for magnetic targeting, it must be shown that low magnetic strength is sufficient to capture flowing nanoparticles. By demonstrating the binding of a therapeutic agent to the surface at medicinal levels, the viability for use as a nanoparticle drug delivery system is improved.

Physical and chemical characterization of biochars derived from different agricultural residues

NASA Astrophysics Data System (ADS)

Jindo, K.; Mizumoto, H.; Sawada, Y.; Sanchez-Monedero, M. A.; Sonoki, T.

2014-12-01

Biochar is widely recognized as an efficient tool for carbon sequestration and soil fertility. The understanding of its chemical and physical properties, which are strongly related to the type of the initial material used and pyrolysis conditions, is crucial to identify the most suitable application of biochar in soil. A selection of organic wastes with different characteristics (e.g., rice husk (RH), rice straw (RS), wood chips of apple tree (Malus pumila) (AB), and oak tree (Quercus serrata) (OB)) were pyrolyzed at different temperatures (400, 500, 600, 700, and 800 °C) in order to optimize the physicochemical properties of biochar as a soil amendment. Low-temperature pyrolysis produced high biochar yields; in contrast, high-temperature pyrolysis led to biochars with a high C content, large surface area, and high adsorption characteristics. Biochar obtained at 600 °C leads to a high recalcitrant character, whereas that obtained at 400 °C retains volatile and easily labile compounds. The biochar obtained from rice materials (RH and RS) showed a high yield and unique chemical properties because of the incorporation of silica elements into its chemical structure. The biochar obtained from wood materials (AB and OB) showed high carbon content and a high absorption character.

Graphite from the University of Idaho Thermolyzed Asphalt Reaction (GUITAR): Fundamental Electrochemical Characterizations

NASA Astrophysics Data System (ADS)

Gyan, Isaiah Owusu

This dissertation details electrochemical characterization of GUITAR (Graphite from the University of Idaho Thermolyzed Asphalt Reaction), a new allotrope of carbon. Applications based on fundamental electrochemical properties of this material are also presented. The dissertation is presented in five chapters. Chapter one presents a summary of the discovery and physical characterizations of GUITAR and how its physical properties position it among carbon materials. In chapter two, fundamental electrochemical properties covering aqueous potential window and electron transfer kinetics with common dissolved redox couples are presented. This chapter highlights significant electrochemical differences between GUITAR and other sp2 carbon materials, notably, fast electron transfer across basal plane GUITAR, contrary to reports at basal planes of graphite and graphene electrodes. In chapter three, the concept of electron transfer facility is extended with biologically relevant molecules. GUITAR is shown to be suitable for biosensing with properties such as; facile electron transfer, low detection limit, high resistance to fouling and stability to anodic regeneration procedures. Chapter four presents further exploration of GUITAR's wide cathodic potential limits in other aqueous electrolytes and preliminary studies towards the exploitation of this property in the negative half of vanadium redox flow battery, where GUITAR-based electrodes are expected to increase coulombic efficiency and increase battery performance due to low hydrogen evolution. Chapter five concludes this dissertation with point-by-point presentation of significant discoveries that highlights GUITAR's uniqueness. This chapter also describes how the various fundamental electrochemical properties of GUITAR make it useful for various applications.

Multifunctional Nanostructured Conductive Polymer Gels: Synthesis, Properties, and Applications

DOE PAGES

Zhao, Fei; Shi, Ye; Pan, Lijia; ...

2017-06-26

Conductive polymers have attracted significant interest over the past few decades because they synergize the advantageous features of conventional polymeric materials and organic conductors. With rationally designed nanostructures, conductive polymers can further exhibit exceptional mechanical, electrical, and optical properties because of their confined dimensions at the nanoscale level. Among various nanostructured conductive polymers, conductive polymer gels (CPGs) with synthetically tunable hierarchical 3D network structures show great potential for a wide range of applications, such as bioelectronics, and energy storage/conversion devices owing to their structural features. CPGs retain the properties of nanosized conductive polymers during the assembly of the nanobuilding blocksmore » into a monolithic macroscopic structure while generating structure-derived features from the highly cross-linked network. In this Account, we review our recent progress on the synthesis, properties, and novel applications of dopant cross-linked CPGs. We first describe the synthetic strategies, in which molecules with multiple functional groups are adopted as cross-linkers to cross-link conductive polymer chains into a 3D molecular network. These cross-linking molecules also act as dopants to improve the electrical conductivity of the gel network. The microstructure and physical/chemical properties of CPGs can be tuned by controlling the synthetic conditions such as species of monomers and cross-linkers, reaction temperature, and solvents. By incorporating other functional polymers or particles into the CPG matrix, hybrid gels have been synthesized with tailored structures. These hybrid gel materials retain the functionalities from each component, as well as enable synergic effects to improve mechanical and electrical properties of CPGs. We then introduce the unique structure-derived properties of the CPGs. The network facilitates both electronic and ionic transport owing to the continuous pathways for electrons and hierarchical pores for ion diffusion. CPGs also provide high surface area and solvent compatibility, similar to natural gels. With these improved properties, CPGs have been explored to enable novel conceptual devices in diverse applications from smart electronics and ultrasensitive biosensors, to energy storage and conversion devices. CPGs have also been adopted for developing hybrid materials with multifunctionalities, such as stimuli responsiveness, self-healing properties, and super-repellency to liquid. With synthetically tunable physical/chemical properties, CPGs emerge as a unique material platform to develop novel multifunctional materials that have the potential to impact electronics, energy, and environmental technologies. Our hope is that this Account promotes further efforts toward synthetic control, fundamental investigation, and application exploration of CPGs.« less

Multifunctional Nanostructured Conductive Polymer Gels: Synthesis, Properties, and Applications

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

Zhao, Fei; Shi, Ye; Pan, Lijia

Conductive polymers have attracted significant interest over the past few decades because they synergize the advantageous features of conventional polymeric materials and organic conductors. With rationally designed nanostructures, conductive polymers can further exhibit exceptional mechanical, electrical, and optical properties because of their confined dimensions at the nanoscale level. Among various nanostructured conductive polymers, conductive polymer gels (CPGs) with synthetically tunable hierarchical 3D network structures show great potential for a wide range of applications, such as bioelectronics, and energy storage/conversion devices owing to their structural features. CPGs retain the properties of nanosized conductive polymers during the assembly of the nanobuilding blocksmore » into a monolithic macroscopic structure while generating structure-derived features from the highly cross-linked network. In this Account, we review our recent progress on the synthesis, properties, and novel applications of dopant cross-linked CPGs. We first describe the synthetic strategies, in which molecules with multiple functional groups are adopted as cross-linkers to cross-link conductive polymer chains into a 3D molecular network. These cross-linking molecules also act as dopants to improve the electrical conductivity of the gel network. The microstructure and physical/chemical properties of CPGs can be tuned by controlling the synthetic conditions such as species of monomers and cross-linkers, reaction temperature, and solvents. By incorporating other functional polymers or particles into the CPG matrix, hybrid gels have been synthesized with tailored structures. These hybrid gel materials retain the functionalities from each component, as well as enable synergic effects to improve mechanical and electrical properties of CPGs. We then introduce the unique structure-derived properties of the CPGs. The network facilitates both electronic and ionic transport owing to the continuous pathways for electrons and hierarchical pores for ion diffusion. CPGs also provide high surface area and solvent compatibility, similar to natural gels. With these improved properties, CPGs have been explored to enable novel conceptual devices in diverse applications from smart electronics and ultrasensitive biosensors, to energy storage and conversion devices. CPGs have also been adopted for developing hybrid materials with multifunctionalities, such as stimuli responsiveness, self-healing properties, and super-repellency to liquid. With synthetically tunable physical/chemical properties, CPGs emerge as a unique material platform to develop novel multifunctional materials that have the potential to impact electronics, energy, and environmental technologies. Our hope is that this Account promotes further efforts toward synthetic control, fundamental investigation, and application exploration of CPGs.« less

Multifunctional Nanostructured Conductive Polymer Gels: Synthesis, Properties, and Applications.

PubMed

Zhao, Fei; Shi, Ye; Pan, Lijia; Yu, Guihua

2017-07-18

Conductive polymers have attracted significant interest over the past few decades because they synergize the advantageous features of conventional polymeric materials and organic conductors. With rationally designed nanostructures, conductive polymers can further exhibit exceptional mechanical, electrical, and optical properties because of their confined dimensions at the nanoscale level. Among various nanostructured conductive polymers, conductive polymer gels (CPGs) with synthetically tunable hierarchical 3D network structures show great potential for a wide range of applications, such as bioelectronics, and energy storage/conversion devices owing to their structural features. CPGs retain the properties of nanosized conductive polymers during the assembly of the nanobuilding blocks into a monolithic macroscopic structure while generating structure-derived features from the highly cross-linked network. In this Account, we review our recent progress on the synthesis, properties, and novel applications of dopant cross-linked CPGs. We first describe the synthetic strategies, in which molecules with multiple functional groups are adopted as cross-linkers to cross-link conductive polymer chains into a 3D molecular network. These cross-linking molecules also act as dopants to improve the electrical conductivity of the gel network. The microstructure and physical/chemical properties of CPGs can be tuned by controlling the synthetic conditions such as species of monomers and cross-linkers, reaction temperature, and solvents. By incorporating other functional polymers or particles into the CPG matrix, hybrid gels have been synthesized with tailored structures. These hybrid gel materials retain the functionalities from each component, as well as enable synergic effects to improve mechanical and electrical properties of CPGs. We then introduce the unique structure-derived properties of the CPGs. The network facilitates both electronic and ionic transport owing to the continuous pathways for electrons and hierarchical pores for ion diffusion. CPGs also provide high surface area and solvent compatibility, similar to natural gels. With these improved properties, CPGs have been explored to enable novel conceptual devices in diverse applications from smart electronics and ultrasensitive biosensors, to energy storage and conversion devices. CPGs have also been adopted for developing hybrid materials with multifunctionalities, such as stimuli responsiveness, self-healing properties, and super-repellency to liquid. With synthetically tunable physical/chemical properties, CPGs emerge as a unique material platform to develop novel multifunctional materials that have the potential to impact electronics, energy, and environmental technologies. We hope that this Account promotes further efforts toward synthetic control, fundamental investigation, and application exploration of CPGs.

Physical properties of evaporite minerals

USGS Publications Warehouse

Robertson, Eugene C.

1962-01-01

The data in the following tables were abstracted from measurements of physical properties of evaporite minerals or of equivalent synthetic compounds. The compounds considered are the halide and sulfate salts which supposedly precipitated from evaporating ocean water and which form very extensive and thick "rock salt" beds. These beds are composed almost entirely of NaCl. In places where the beds are deeply buried and where fractures occur in the overlying rocks, the salt is plastically extruded upward as in a pipe to form the "salt domes". Most of the tables are for NaCl, both the natural (halite) and the synthetic salt, polycrystalline and single crystals. These measurements have been collected for use 1) in studies on storage of radioactive wastes in salt domes or beds, 2) in calculations concerned with nuclear tests in salt domes and beds, and 3) in studies of phenomena in salt of geologic interest. Rather than an exhaustive compilation of physical property measurements, there tables represent a summary of data from accessible sources. As limitations of time have presented making a more systematic and comprehensive selection, the data given may seem arbitrarily chosen. Some of the data listed are old, and newer, more accurate data are undoubtedly available. Halite (an synthetic NaCl) has been very thoroughly studied because of its relatively simple and highly symmetrical crystal structure, its easy availability naturally or synthetically, both in single crystals and polycrystalline, its useful and scientifically interesting properties, and its role as a compound of almost purely ionic bonding. The measurements of NaCl in the tables, however, represent only a small part of the total number of observations; discrimination was necessary to keep the size of the tabulations manageable. The physical properties of the evaporite minerals other than halite and sylvite have received only desultory attention of experiementalists, and appear in only a few tables. The effects of temperature, hydrostatic pressure, stress difference, and other mechanical, eletrical, and optical conditions on the physical properties have probably been observed more completely on NaCl than on any other solid substance, which makes it a unique and important substance. Several new and important phenomena have been observed first on it. The mechanical properties of NaCl, for example, depend very strongly on the condition and the composition of the gas or liquid in contact with the sample surface; the data are sparse as yet and are not reported here.

Tissue deposition and toxicological effects of commercially significant rare earth oxide nanomaterials: Material and physical properties.

PubMed

Das, Soumen; Reed McDonagh, Philip; Selvan Sakthivel, Tamil; Barkam, Swetha; Killion, Kelsey; Ortiz, Julian; Saraf, Shashank; Kumar, Amit; Gupta, Ankur; Zweit, Jamal; Seal, Sudipta

2017-03-01

Rare earth oxide (REO) materials are found naturally in earth's crust and at the nanoscale these REO nanoparticles exhibit unique thermal, electrical, and physicochemical properties. REO nanoparticles are widely used in different industrial sectors for ceramics, glass polishing, metallurgy, lasers, and magnets. Recently, some of these REO nanoparticles have been identified for their potential application in medicine, including therapy, imaging, and diagnostics. Concurrent research into the REO nanomaterials' toxicities has also raised concern for their environmental impacts. The correlation of REO nanoparticles mediated toxicity with their physiochemical properties can help to design nanoparticles with minimal effect on the environment and living organisms. In vitro assay revealed toxicity toward Human squamous epithelial cell line (CCL30) and Human umbilical vascular endothelial cells (HUVEC) at a concentration of 100 µM and higher. In vivo results showed, with the exception of CeO 2 and Gd 2 O 3 , most of the naoparticles did not clear or had minimum clearance (10-20%) from the system. Elevated levels of alanine transferase were seen for animals given each different nanoparticle, however the increases were not significant for CeO 2 and Dy 2 O 3 . Nephrotoxicity was only seen in case of Dy 2 O 3 and Gd 2 O 3 . Lastly, histological examination revealed presence of swollen hepatocytes which further confirms toxicity of the commercial REO nanomaterials. The in vivo toxicity is mainly due to excessive tissue deposition (70-90%) due to the commercial REO nanoparticles' poor physical properties (shape, stability, and extent of agglomeration). Therefore, optimization of nanoparticles physical properties is very important. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 904-917, 2017. © 2016 Wiley Periodicals, Inc.

Manipulation of particles by weak forces

NASA Technical Reports Server (NTRS)

Adler, M. S.; Savkar, S. D.; Summerhayes, H. R.

1972-01-01

Quantitative relations between various force fields and their effects on the motion of particles of various sizes and physical characteristics were studied. The forces considered were those derived from light, heat, microwaves, electric interactions, magnetic interactions, particulate interactions, and sound. A physical understanding is given of the forces considered as well as formulae which express how the size of the force depends on the physical and electrical properties of the particle. The drift velocity in a viscous fluid is evaluated as a function of initial acceleration and the effects of thermal random motion are considered. A means of selectively sorting or moving particles by choosing a force system and/or environment such that the particle of interest reacts uniquely was developed. The forces considered and a demonstration of how the initial acceleration, drift velocity, and ultimate particle density distribution is affected by particle, input, and environmental parameters are tabulated.

DNA-Based Applications in Nanobiotechnology

PubMed Central

Abu-Salah, Khalid M.; Ansari, Anees A.; Alrokayan, Salman A.

2010-01-01

Biological molecules such as deoxyribonucleic acid (DNA) have shown great potential in fabrication and construction of nanostructures and devices. The very properties that make DNA so effective as genetic material also make it a very suitable molecule for programmed self-assembly. The use of DNA to assemble metals or semiconducting particles has been extended to construct metallic nanowires and functionalized nanotubes. This paper highlights some important aspects of conjugating the unique physical properties of dots or wires with the remarkable recognition capabilities of DNA which could lead to miniaturizing biological electronics and optical devices, including biosensors and probes. Attempts to use DNA-based nanocarriers for gene delivery are discussed. In addition, the ecological advantages and risks of nanotechnology including DNA-based nanobiotechnology are evaluated. PMID:20652049

Fullerene-like hydrogenated carbon films with super-low friction and wear, and low sensitivity to environment

NASA Astrophysics Data System (ADS)

Ji, Li; Li, Hongxuan; Zhao, Fei; Quan, Weilong; Chen, Jianmin; Zhou, Huidi

2010-01-01

A novel hydrogenated carbon film containing fullerene-like nanostructure was prepared by pulse bias-assisted plasma enhanced chemical vapour deposition, and the fullerene-like arrangement in the film was characterized by high resolution transmission electron microscopy. The as-prepared hydrogenated carbon film exhibited super-low friction and wear in both dry N2 and humid ambient atmospheres, and was superior to the conventional hydrogenated carbon films. These excellent tribological properties could be attributed to the unique fullerene-like nanostructure, which endows the film with some special chemical and physical features, such as high chemical inertness, hardness and elastic recovery owing to the closed, curved and caged graphite planes, and hence, improves the tribological properties of the hydrogenated carbon film.

DNA-based applications in nanobiotechnology.

PubMed

Abu-Salah, Khalid M; Ansari, Anees A; Alrokayan, Salman A

2010-01-01

Biological molecules such as deoxyribonucleic acid (DNA) have shown great potential in fabrication and construction of nanostructures and devices. The very properties that make DNA so effective as genetic material also make it a very suitable molecule for programmed self-assembly. The use of DNA to assemble metals or semiconducting particles has been extended to construct metallic nanowires and functionalized nanotubes. This paper highlights some important aspects of conjugating the unique physical properties of dots or wires with the remarkable recognition capabilities of DNA which could lead to miniaturizing biological electronics and optical devices, including biosensors and probes. Attempts to use DNA-based nanocarriers for gene delivery are discussed. In addition, the ecological advantages and risks of nanotechnology including DNA-based nanobiotechnology are evaluated.

On the impact of the magnitude of interstellar pressure on physical properties of molecular cloud

NASA Astrophysics Data System (ADS)

Anathpindika, S.; Burkert, A.; Kuiper, R.

2017-04-01

Recently reported variations in the typical physical properties of Galactic and extra-Galactic molecular clouds (MCs), and, in their star-forming ability, have been attributed to local variations in the magnitude of interstellar pressure. Inferences from these surveys have called into question two long-standing beliefs that: (1) MCs are virialized and (2) they obey the Larson's third law. Here we invoked the framework of cloud formation via collision between warm gas-flows to examine if these latest observational inferences can be reconciled. To this end, we traced the temporal evolution of the gas surface density, the fraction of dense gas, the distribution of gas column density (N-PDF) and the virial nature of the assembled clouds. We conclude that these physical properties exhibit temporal variation and their respective peak magnitude also increases in proportion with the magnitude of external pressure, Pext. The velocity dispersion in assembled clouds appears to follow the power law, σ _{gas}∝ P_{ext}^{0.23}. The power-law tail of the N-PDFs at higher densities becomes shallower with increasing magnitude of external pressure for Pext/kB ≲ 107 K cm-3; at higher magnitudes such as those typically found in the Galactic Central Molecular Zone (Pext/kB > 107 K cm-3), the power-law shows significant steepening. While our results are broadly consistent with inferences from various recent observational surveys, it appears that MCs do not exhibit a unique set of properties, but rather a wide variety that can be reconciled with a range of magnitudes of pressure between 104 and 108 K cm-3.

Nanoparticles and DNA - a powerful and growing functional combination in bionanotechnology

NASA Astrophysics Data System (ADS)

Samanta, Anirban; Medintz, Igor L.

2016-04-01

Functionally integrating DNA and other nucleic acids with nanoparticles in all their different physicochemical forms has produced a rich variety of composite nanomaterials which, in many cases, display unique or augmented properties due to the synergistic activity of both components. These capabilities, in turn, are attracting greater attention from various research communities in search of new nanoscale tools for diverse applications that include (bio)sensing, labeling, targeted imaging, cellular delivery, diagnostics, therapeutics, theranostics, bioelectronics, and biocomputing to name just a few amongst many others. Here, we review this vibrant and growing research area from the perspective of the materials themselves and their unique capabilities. Inorganic nanocrystals such as quantum dots or those made from gold or other (noble) metals along with metal oxides and carbon allotropes are desired as participants in these hybrid materials since they can provide distinctive optical, physical, magnetic, and electrochemical properties. Beyond this, synthetic polymer-based and proteinaceous or viral nanoparticulate materials are also useful in the same role since they can provide a predefined and biocompatible cargo-carrying and targeting capability. The DNA component typically provides sequence-based addressability for probes along with, more recently, unique architectural properties that directly originate from the burgeoning structural DNA field. Additionally, DNA aptamers can also provide specific recognition capabilities against many diverse non-nucleic acid targets across a range of size scales from ions to full protein and cells. In addition to appending DNA to inorganic or polymeric nanoparticles, purely DNA-based nanoparticles have recently surfaced as an excellent assembly platform and have started finding application in areas like sensing, imaging and immunotherapy. We focus on selected and representative nanoparticle-DNA materials and highlight their myriad applications using examples from the literature. Overall, it is clear that this unique functional combination of nanomaterials has far more to offer than what we have seen to date and as new capabilities for each of these materials are developed, so, too, will new applications emerge.

Unusual inhomogeneous microstructures in charge glass state of PbCrO3

NASA Astrophysics Data System (ADS)

Kurushima, Kosuke; Tsukasaki, Hirofumi; Ogata, Takahiro; Sakai, Yuki; Azuma, Masaki; Ishii, Yui; Mori, Shigeo

2018-05-01

We investigated the microstructures and local structures of perovskite PbCrO3, which shows a metal-to-insulator transition and a 9.8% volume collapse, by electron diffraction, high-resolution transmission electron microscopy (TEM), and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). It is revealed that the charge glass state is characterized by the unique coexistence of the crystalline state with a cubic symmetry on average and the noncrystalline state. HAADF-STEM observation at atomic resolution revealed that Pb ions were displaced from the ideal A site position of the cubic perovskite structure, which gives rise to characteristic diffuse scatterings around the fundamental Bragg reflections. These structural inhomogeneities are crucial to the understanding of the unique physical properties in the charge glass state of PbCrO3.

Stochastic lumping analysis for linear kinetics and its application to the fluctuation relations between hierarchical kinetic networks.

PubMed

Deng, De-Ming; Chang, Cheng-Hung

2015-05-14

Conventional studies of biomolecular behaviors rely largely on the construction of kinetic schemes. Since the selection of these networks is not unique, a concern is raised whether and under which conditions hierarchical schemes can reveal the same experimentally measured fluctuating behaviors and unique fluctuation related physical properties. To clarify these questions, we introduce stochasticity into the traditional lumping analysis, generalize it from rate equations to chemical master equations and stochastic differential equations, and extract the fluctuation relations between kinetically and thermodynamically equivalent networks under intrinsic and extrinsic noises. The results provide a theoretical basis for the legitimate use of low-dimensional models in the studies of macromolecular fluctuations and, more generally, for exploring stochastic features in different levels of contracted networks in chemical and biological kinetic systems.

Excitons in atomically thin 2D semiconductors and their applications

NASA Astrophysics Data System (ADS)

Xiao, Jun; Zhao, Mervin; Wang, Yuan; Zhang, Xiang

2017-06-01

The research on emerging layered two-dimensional (2D) semiconductors, such as molybdenum disulfide (MoS2), reveals unique optical properties generating significant interest. Experimentally, these materials were observed to host extremely strong light-matter interactions as a result of the enhanced excitonic effect in two dimensions. Thus, understanding and manipulating the excitons are crucial to unlocking the potential of 2D materials for future photonic and optoelectronic devices. In this review, we unravel the physical origin of the strong excitonic effect and unique optical selection rules in 2D semiconductors. In addition, control of these excitons by optical, electrical, as well as mechanical means is examined. Finally, the resultant devices such as excitonic light emitting diodes, lasers, optical modulators, and coupling in an optical cavity are overviewed, demonstrating how excitons can shape future 2D optoelectronics.

Fundamental Properties of One-Dimensional Zinc Oxide Nanomaterials and Implementations in Various Detection Modes of Enhanced Biosensing

PubMed Central

Hahm, Jong-in

2016-01-01

Recent bioapplications of one-dimensional (1D) zinc oxide (ZnO) nanomaterials, despite the short development period, have shown promising signs as new sensors and assay platforms offering exquisite biomolecular sensitivity and selectivity. The incorporation of 1D ZnO nanomaterials has proven beneficial to various modes of biodetection owing to their inherent properties. The more widely explored electrochemical and electrical approaches tend to capitalize on the reduced physical dimensionality, yielding a high surface-to-volume ratio, as well as on the electrical properties of ZnO. The newer development of the use of 1D ZnO nanomaterials in fluorescence-based biodetection exploits the innate optical property of their high anisotropy. This review considers stimulating research advances made to identify and understand fundamental properties of 1D ZnO nanomaterials, and examines various biosensing modes utilizing them, while focusing on the unique optical properties of individual and ensembles of 1D ZnO nanomaterials specifically pertaining to their bio-optical applications in simple and complex fluorescence assays. PMID:27215822

CALIPSO: Global Aerosol and Cloud Observations from Lidar and Passive Instruments

NASA Technical Reports Server (NTRS)

Poole, L. R.; Winker, D. M.; Pelon, J. R.; McCormick, M. P.

2002-01-01

CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Spaceborne Observations) is an approved satellite mission being developed through collaboration between NASA and the French space agency CNES. The mission is scheduled for launch in 2004 and will operate for 3 years as part of a five-satellite formation called the Aqua constellation. This constellation will provide a unique data set on aerosol and cloud optical and physical properties and aerosol-cloud interactions that will substantially increase our understanding of the climate system and the potential for climate change.

Quantum Dots for Molecular Diagnostics of Tumors

PubMed Central

Zdobnova, T.A.; Lebedenko, E.N.; Deyev, S.М.

2011-01-01

Semiconductor quantum dots (QDs) are a new class of fluorophores with unique physical and chemical properties, which allow to appreciably expand the possibilities for the current methods of fluorescent imaging and optical diagnostics. Here we discuss the prospects of QD application for molecular diagnostics of tumors ranging from cancer-specific marker detection on microplates to non-invasive tumor imagingin vivo. We also point out the essential problems that require resolution in order to clinically promote QD, and we indicate innovative approaches to oncology which are implementable using QD. PMID:22649672

Articular cartilage. Part I. The normal joint.

PubMed

Muehleman, C; Arsenis, C H

1995-05-01

Articular hyaline cartilage is of interest to both the clinician and the basic scientist because of its unique physical and chemical properties which are a consequence of its biochemical composition. Although it is a tissue which is hypocellular, avascular, and also lacks nerves and lymphatics, it is active in synthesis and degradation. Articular cartilage responds to the forces to which it is subjected and, in this way, maintains its integrity as long as those forces do not exceed the tissue's capacity for repair or permanently change the biologic response of the cells.

Micro-Raman Analysis of Irradiated Diamond Films

NASA Technical Reports Server (NTRS)

Newton, Robert L.

2003-01-01

Owing to its unique and robust physical properties, diamond is a much sought after material for use in advanced technologies, even in Microelectromechanical Systems (MEMS). The volume and weight savings promised by MEMS-based devices are of particular interest to spaceflight applications. However, much basic materials science research remains to be completed in this field. Results of micro-Raman analysis of proton (10(exp 15) - 10(exp 17) H(+)/sq cm doses) irradiated chemical vapor deposited (CVD) films are presented and indicate that their microstructure is retained even after high radiation exposure.

Recent advances on polyoxometalate-based molecular and composite materials.

PubMed

Song, Yu-Fei; Tsunashima, Ryo

2012-11-21

Polyoxometalates (POMs) are a subset of metal oxides with unique physical and chemical properties, which can be reliably modified through various techniques and methods to develop sophisticated materials and devices. In parallel with the large number of new crystal structures reported in the literature, the application of these POMs towards multifunctional materials has attracted considerable attention. This critical review summarizes recent progress on POM-based molecular and composite materials, and particularly highlights the emerging areas that are closely related to surface, electronic, energy, environment, life science, etc. (171 references).

Development of a polymetric grout for the hydrostatic bearing at DSS 14

NASA Technical Reports Server (NTRS)

Mcclung, C. E.; Schwendeman, J. L.; Ball, G. L., III; Jenkins, G. H.; Casperson, R. D.; Gale, G. P.; Riewe, A. A.

1981-01-01

Results of an investigation into the causes of the deterioration and premature failure of the grout under the hydrostatic bearing runner at DSS 14 are reported. Generic types of materials were screened and tested to find a grout material more resistive to the causes of grout failure. Emphasis was placed on the physical properties, strength, modulus of elasticity, and resistance to erosion and chemical attack by oil and unique requirements imposed by each material for mixing, placing, compacting, and cooling. The polymetric grout developed to replace the dry grout is described.

The Applications of Gold Nanoparticle-Initialed Chemiluminescence in Biomedical Detection

NASA Astrophysics Data System (ADS)

Liu, Zezhong; Zhao, Furong; Gao, Shandian; Shao, Junjun; Chang, Huiyun

2016-10-01

Chemiluminescence technique as a novel detection method has gained much attention in recent years owning to the merits of high sensitivity, wider linear ranges, and low background signal. Similarly, nanotechnology especially for gold nanoparticles has emerged as detection tools due to their unique physical and chemical properties. Recently, it has become increasingly popular to couple gold nanoparticles with chemiluminescence technique in biological agents' detection. In this review, we describe the superiority of both chemiluminescence and gold nanoparticles and conclude the different applications of gold nanoparticle-initialed chemiluminescence in biomedical detection.

A Study of the Surface Structure of Polymorphic Graphene and Other Two-Dimensional Materials for Use in Novel Electronics and Organic Photovoltaics

NASA Astrophysics Data System (ADS)

Grady, Maxwell

For some time there has been interest in the fundamental physical properties of low- dimensional material systems. The discovery of graphene as a stable two-dimensional form of solid carbon lead to an exponential increase in research in two-dimensional and other re- duced dimensional systems. It is now known that there is a wide range of materials which are stable in two-dimensional form. These materials span a large configuration space of struc- tural, mechanical, and electronic properties, which results in the potential to create novel electronic devices from nano-scale heterostructures with exactly tailored device properties. Understanding the material properties at the nanoscale level requires specialized tools to probe materials with atomic precision. Here I present the growth and analysis of a novel graphene-ruthenium system which exhibits unique polymorphism in its surface structure, hereby referred to as polymorphic graphene. Scanning Tunneling Microscopy (STM) investigations of the polymorphic graphene surface reveal a periodically rippled structure with a vast array of domains, each exhibiting xvia unique moire period. The majority of moire domains found in this polymorphic graphene system are previously unreported in past studies of the structure of graphene on ruthenium. To better understand many of the structural properties of this system, characterization methods beyond those available at the UNH surface science lab are employed. Further investigation using Low Energy Electron Microscopy (LEEM) has been carried out at Sandia National Laboratory's Center for Integrated Nanotechnology and the Brookhaven National Laboratory Center for Functional Nanomaterials. To aid in analysis of the LEEM data, I have developed an open source software package to automate extraction of electron reflectivity curves from real space and reciprocal space data sets. This software has been used in the study of numerous other two-dimensional materials beyond graphene. When combined with computational modeling, the analysis of electron I(V) curves presents a method to quantify structural parameters in a material with angstrom level precision. While many materials studied in this thesis offer unique electronic properties, my work focuses primarily on their structural aspects, as well as the instrumentation required to characterize the structure with ultra high resolution.

Two-Dimensional Semiconductor Optoelectronics Based on van der Waals Heterostructures.

PubMed

Lee, Jae Yoon; Shin, Jun-Hwan; Lee, Gwan-Hyoung; Lee, Chul-Ho

2016-10-27

Two-dimensional (2D) semiconductors such as transition metal dichalcogenides (TMDCs) and black phosphorous have drawn tremendous attention as an emerging optical material due to their unique and remarkable optical properties. In addition, the ability to create the atomically-controlled van der Waals (vdW) heterostructures enables realizing novel optoelectronic devices that are distinct from conventional bulk counterparts. In this short review, we first present the atomic and electronic structures of 2D semiconducting TMDCs and their exceptional optical properties, and further discuss the fabrication and distinctive features of vdW heterostructures assembled from different kinds of 2D materials with various physical properties. We then focus on reviewing the recent progress on the fabrication of 2D semiconductor optoelectronic devices based on vdW heterostructures including photodetectors, solar cells, and light-emitting devices. Finally, we highlight the perspectives and challenges of optoelectronics based on 2D semiconductor heterostructures.

Cellulose nanocrystals: synthesis, functional properties, and applications

PubMed Central

George, Johnsy; Sabapathi, SN

2015-01-01

Cellulose nanocrystals are unique nanomaterials derived from the most abundant and almost inexhaustible natural polymer, cellulose. These nanomaterials have received significant interest due to their mechanical, optical, chemical, and rheological properties. Cellulose nanocrystals primarily obtained from naturally occurring cellulose fibers are biodegradable and renewable in nature and hence they serve as a sustainable and environmentally friendly material for most applications. These nanocrystals are basically hydrophilic in nature; however, they can be surface functionalized to meet various challenging requirements, such as the development of high-performance nanocomposites, using hydrophobic polymer matrices. Considering the ever-increasing interdisciplinary research being carried out on cellulose nanocrystals, this review aims to collate the knowledge available about the sources, chemical structure, and physical and chemical isolation procedures, as well as describes the mechanical, optical, and rheological properties, of cellulose nanocrystals. Innovative applications in diverse fields such as biomedical engineering, material sciences, electronics, catalysis, etc, wherein these cellulose nanocrystals can be used, are highlighted. PMID:26604715

Zinc Oxide Nanoparticles for Revolutionizing Agriculture: Synthesis and Applications

PubMed Central

Sabir, Sidra; Arshad, Muhammad

2014-01-01

Nanotechnology is the most innovative field of 21st century. Extensive research is going on for commercializing nanoproducts throughout the world. Due to their unique properties, nanoparticles have gained considerable importance compared to bulk counterparts. Among other metal nanoparticles, zinc oxide nanoparticles are very much important due to their utilization in gas sensors, biosensors, cosmetics, drug-delivery systems, and so forth. Zinc oxide nanoparticles (ZnO NPs) also have remarkable optical, physical, and antimicrobial properties and therefore have great potential to enhance agriculture. As far as method of formation is concerned, ZnO NPs can be synthesized by several chemical methods such as precipitation method, vapor transport method, and hydrothermal process. The biogenic synthesis of ZnO NPs by using different plant extracts is also common nowadays. This green synthesis is quite safe and ecofriendly compared to chemical synthesis. This paper elaborates the synthesis, properties, and applications of zinc oxide nanoparticles. PMID:25436235

Current density tensors

NASA Astrophysics Data System (ADS)

Lazzeretti, Paolo

2018-04-01

It is shown that nonsymmetric second-rank current density tensors, related to the current densities induced by magnetic fields and nuclear magnetic dipole moments, are fundamental properties of a molecule. Together with magnetizability, nuclear magnetic shielding, and nuclear spin-spin coupling, they completely characterize its response to magnetic perturbations. Gauge invariance, resolution into isotropic, deviatoric, and antisymmetric parts, and contributions of current density tensors to magnetic properties are discussed. The components of the second-rank tensor properties are rationalized via relationships explicitly connecting them to the direction of the induced current density vectors and to the components of the current density tensors. The contribution of the deviatoric part to the average value of magnetizability, nuclear shielding, and nuclear spin-spin coupling, uniquely determined by the antisymmetric part of current density tensors, vanishes identically. The physical meaning of isotropic and anisotropic invariants of current density tensors has been investigated, and the connection between anisotropy magnitude and electron delocalization has been discussed.

Two-Dimensional Semiconductor Optoelectronics Based on van der Waals Heterostructures

PubMed Central

Lee, Jae Yoon; Shin, Jun-Hwan; Lee, Gwan-Hyoung; Lee, Chul-Ho

2016-01-01

Two-dimensional (2D) semiconductors such as transition metal dichalcogenides (TMDCs) and black phosphorous have drawn tremendous attention as an emerging optical material due to their unique and remarkable optical properties. In addition, the ability to create the atomically-controlled van der Waals (vdW) heterostructures enables realizing novel optoelectronic devices that are distinct from conventional bulk counterparts. In this short review, we first present the atomic and electronic structures of 2D semiconducting TMDCs and their exceptional optical properties, and further discuss the fabrication and distinctive features of vdW heterostructures assembled from different kinds of 2D materials with various physical properties. We then focus on reviewing the recent progress on the fabrication of 2D semiconductor optoelectronic devices based on vdW heterostructures including photodetectors, solar cells, and light-emitting devices. Finally, we highlight the perspectives and challenges of optoelectronics based on 2D semiconductor heterostructures. PMID:28335321

High Temperature Transfer Molding Resins Based on 2,3,3',4'-Biphenyltetracarboxylic Dianhydride

NASA Technical Reports Server (NTRS)

Smith, J. G., Jr.; Connell, J. W.; Hergenrother, P. M.; Yokota, R.; Criss, J. M.

2002-01-01

As part of an ongoing effort to develop materials for resin transfer molding (RTM) processes to fabricate high performance/high temperature composite structures, phenylethynyl containing imides have been under investigation. New phenylethynyl containing imide compositions were prepared using 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA) and evaluated for cured glass transition temperature (Tg), melt flow behavior, and for processability into flat composite panels via RTM. The a-BPDA imparts a unique combination of properties that are desirable for high temperature transfer molding resins. In comparison to its symmetrical counterpart (i.e. 3,3',4,4'-biphenyltetracarboxylic dianhydride), a-BPDA affords oligomers with lower melt viscosities and when cured, higher Tgs. Several candidates exhibited the appropriate combination of properties such as a low and stable melt viscosity required for RTM processes, high cured Tg, and moderate toughness. The chemistry, physical, and composite properties of select resins will be discussed.

Application of atomic force microscopy to microbial surfaces: from reconstituted cell surface layers to living cells.

PubMed

Dufrêne, Y F

2001-02-01

The application of atomic force microscopy (AFM) to probe the ultrastructure and physical properties of microbial cell surfaces is reviewed. The unique capabilities of AFM can be summarized as follows: imaging surface topography with (sub)nanometer lateral resolution; examining biological specimens under physiological conditions; measuring local properties and interaction forces. AFM is being used increasingly for: (i) visualizing the surface ultrastructure of microbial cell surface layers, including bacterial S-layers, purple membranes, porin OmpF crystals and fungal rodlet layers; (ii) monitoring conformational changes of individual membrane proteins; (iii) examining the morphology of bacterial biofilms, (iv) revealing the nanoscale structure of living microbial cells, including fungi, yeasts and bacteria, (v) mapping interaction forces at microbial surfaces, such as van der Waals and electrostatic forces, solvation forces, and steric/bridging forces; and (vi) probing the local mechanical properties of cell surface layers and of single cells.

Synthesis, functionalization, and applications of metal-organic frameworks in biomedicine.

PubMed

Chen, Wei; Wu, Chunsheng

2018-02-13

Metal-organic frameworks (MOFs), also known as coordination polymers, have attracted extensive research interest in the past few decades due to their unique physical structures and potentially vast applications. In this review, we outline the recent progress in the synthesis, functionalization and applications of MOFs in biomedicine, mainly focusing on two promising, yet challenging areas, i.e., drug delivery and biosensing applications. A major challenge is the proper functionalization of MOFs with demanding properties suitable for biomedical applications. Extensive studies on MOFs in biomedicine have led to substantial progress in the control of key properties of MOFs such as toxicity, size and shape, and biological stability. Due to their flexible composition, pore size and easy functionalization properties, MOFs can be utilized as key components for the development of various functional systems, and their applications in drug delivery and biosensing are reviewed. Future trends and perspectives in these research areas are also outlined.

Floquet topological insulators for sound

NASA Astrophysics Data System (ADS)

Fleury, Romain; Khanikaev, Alexander B.; Alù, Andrea

2016-06-01

The unique conduction properties of condensed matter systems with topological order have recently inspired a quest for the similar effects in classical wave phenomena. Acoustic topological insulators, in particular, hold the promise to revolutionize our ability to control sound, allowing for large isolation in the bulk and broadband one-way transport along their edges, with topological immunity against structural defects and disorder. So far, these fascinating properties have been obtained relying on moving media, which may introduce noise and absorption losses, hindering the practical potential of topological acoustics. Here we overcome these limitations by modulating in time the acoustic properties of a lattice of resonators, introducing the concept of acoustic Floquet topological insulators. We show that acoustic waves provide a fertile ground to apply the anomalous physics of Floquet topological insulators, and demonstrate their relevance for a wide range of acoustic applications, including broadband acoustic isolation and topologically protected, nonreciprocal acoustic emitters.

Exotic Physics and Chemistry of Two-Dimensional Phosphorus: Phosphorene.

PubMed

Chowdhury, Chandra; Datta, Ayan

2017-07-06

Phosphorene, the monolayer form of black phosphorus, is the most recent addition to graphene-like van der Waals two-dimensional (2D) systems. Due to its several interesting properties, namely its tunable direct band gap, high carrier mobility, and unique in-plane anisotropy, it has emerged as a promising candidate for electronic and optoelectronic devices. Phosphorene (Pn) reveals a much richer phase diagram than graphene, and it comprises the two forms namely the stapler-clip like (black Pn, α form) and chairlike (blue Pn, β form) structures. Regardless of its favorable properties, black Pn suffers from instability in oxygen and water, which limits its successful applications in electronic devices. In this Perspective, the cause of structural diversity of Pn, which leads to different properties of both black and blue Pn, is discussed. We provide possible solutions for protecting phosphorene from chemical degradation and its applications in the field of energy storage namely for Li and Na ion batteries.

Optical properties of group-3 metal hexaboride nanoparticles by first-principles calculations

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

Yoshio, Satoshi; Maki, Koichiro; Adachi, Kenji, E-mail: kenji-adachi@ni.smm.co.jp

2016-06-21

LaB{sub 6} nanoparticles are widely used as solar control materials for strong near-infrared absorption and high visible transparency. In order to elucidate the origin of this unique optical property, first-principles calculations have been made for the energy-band structure and dielectric functions of R{sup III}B{sub 6} (R{sup III} = Sc, Y, La, Ac). On account of the precise assessment of the energy eigenvalues of vacant states in conduction band by employing the screened exchange method, as well as to the incorporation of the Drude term, dielectric functions and various physical properties of LaB{sub 6} have been reproduced in excellent agreement withmore » experimental values. Systematic examinations of dielectric functions and electronic structures of the trivalent metal hexaborides have clarified the origin of the visible transparency and the near-infrared plasmon absorption of R{sup III}B{sub 6} nanoparticles.« less

Zinc oxide nanoparticles for revolutionizing agriculture: synthesis and applications.

PubMed

Sabir, Sidra; Arshad, Muhammad; Chaudhari, Sunbal Khalil

2014-01-01

Nanotechnology is the most innovative field of 21st century. Extensive research is going on for commercializing nanoproducts throughout the world. Due to their unique properties, nanoparticles have gained considerable importance compared to bulk counterparts. Among other metal nanoparticles, zinc oxide nanoparticles are very much important due to their utilization in gas sensors, biosensors, cosmetics, drug-delivery systems, and so forth. Zinc oxide nanoparticles (ZnO NPs) also have remarkable optical, physical, and antimicrobial properties and therefore have great potential to enhance agriculture. As far as method of formation is concerned, ZnO NPs can be synthesized by several chemical methods such as precipitation method, vapor transport method, and hydrothermal process. The biogenic synthesis of ZnO NPs by using different plant extracts is also common nowadays. This green synthesis is quite safe and ecofriendly compared to chemical synthesis. This paper elaborates the synthesis, properties, and applications of zinc oxide nanoparticles.

Floquet topological insulators for sound

PubMed Central

Fleury, Romain; Khanikaev, Alexander B; Alù, Andrea

2016-01-01

The unique conduction properties of condensed matter systems with topological order have recently inspired a quest for the similar effects in classical wave phenomena. Acoustic topological insulators, in particular, hold the promise to revolutionize our ability to control sound, allowing for large isolation in the bulk and broadband one-way transport along their edges, with topological immunity against structural defects and disorder. So far, these fascinating properties have been obtained relying on moving media, which may introduce noise and absorption losses, hindering the practical potential of topological acoustics. Here we overcome these limitations by modulating in time the acoustic properties of a lattice of resonators, introducing the concept of acoustic Floquet topological insulators. We show that acoustic waves provide a fertile ground to apply the anomalous physics of Floquet topological insulators, and demonstrate their relevance for a wide range of acoustic applications, including broadband acoustic isolation and topologically protected, nonreciprocal acoustic emitters. PMID:27312175

Microwave assisted growth of nanorods vanadium dioxide VO2 (R): structural and electrical properties

NASA Astrophysics Data System (ADS)

Derkaoui, I.; Khenfouch, M.; Mothudi, B. M.; Moloi, S. J.; Zorkani, I.; Jorio, A.; Maaza, M.

2018-03-01

Nanostructured metal oxides have attracted a lot of attention recently owning to their unique structural advantages and demonstrated promising chemical and physical properties for various applications. In this study, we report the structural and electrical properties of vanadium dioxide VO2 (R) prepared via a single reaction microwave (SRC) synthesis. Our results are revealing that the components of VO2 (R) films have a rod-like shape with a uniform size distribution. The nanorods with very smooth and flat surfaces have a typical length of up to 2μm and a width of about several nanometers. The structural investigations reveal the high crystallinity of VO2 (R) ensuring good electrical contact and showing a high conductivity as a function of temperature. This synthesis method provides a new simple route to fabricate one-dimensional nanostructured metal oxides which is suitable for a large field of applications especially for smart windows.

Porous silicon platform for optical detection of functionalized magnetic particles biosensing.

PubMed

Ko, Pil Ju; Ishikawa, Ryousuke; Sohn, Honglae; Sandhu, Adarsh

2013-04-01

The physical properties of porous materials are being exploited for a wide range of applications including optical biosensors, waveguides, gas sensors, micro capacitors, and solar cells. Here, we review the fast, easy and inexpensive electrochemical anodization based fabrication porous silicon (PSi) for optical biosensing using functionalized magnetic particles. Combining magnetically labeled biomolecules with PSi offers a rapid and one-step immunoassay and real-time detection by magnetic manipulation of superparamagnetic beads (SPBs) functionalized with target molecules onto corresponding probe molecules immobilized inside nano-pores of PSi. We first give an introduction to electrochemical and chemical etching procedures used to fabricate a wide range of PSi structures. Next, we describe the basic properties of PSi and underlying optical scattering mechanisms that govern their unique optical properties. Finally, we give examples of our experiments that demonstrate the potential of combining PSi and magnetic beads for real-time point of care diagnostics.

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

Jiang, Xiujuan; Whalen, Scott A.; Darsell, Jens T.

Soft magnetic materials are often limited in scalability due to conventional processes that do not retain beneficial microstructures, and their associated physical properties, during densification. In this work, friction consolidation (FC) has been studied to fabricate Fe-Si soft magnetic materials from gas-atomized powder precursors. Fe-Si powder is consolidated using variable pressure and tool rotation speed in an effort to evaluate this unique densification approach for potential improvements in magnetic properties. FC, due to the high shear deformation involved, is shown to result in uniform gradual grain structure refinement across the consolidated workpiece from the center nearest the tool to themore » edge. Magnetic properties along different orientations indicate little, if any, textural orientation in the refined grain structure. The effect of annealing on the magnetic properties is evaluated and shown to decrease coercivity. FC processing was able to retain the magnetization of the original gas-atomized powders but further process optimization is needed to reach the optimal coercivity for the soft magnetic materials applications.« less

Strength and fatigue properties of three-step sintered dense nanocrystal hydroxyapatite bioceramics

NASA Astrophysics Data System (ADS)

Guo, Wen-Guang; Qiu, Zhi-Ye; Cui, Han; Wang, Chang-Ming; Zhang, Xiao-Jun; Lee, In-Seop; Dong, Yu-Qi; Cui, Fu-Zhai

2013-06-01

Dense hydroxyapatite (HA) ceramic is a promising material for hard tissue repair due to its unique physical properties and biologic properties. However, the brittleness and low compressive strength of traditional HA ceramics limited their applications, because previous sintering methods produced HA ceramics with crystal sizes greater than nanometer range. In this study, nano-sized HA powder was employed to fabricate dense nanocrystal HA ceramic by high pressure molding, and followed by a three-step sintering process. The phase composition, microstructure, crystal dimension and crystal shape of the sintered ceramic were examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Mechanical properties of the HA ceramic were tested, and cytocompatibility was evaluated. The phase of the sintered ceramic was pure HA, and the crystal size was about 200 nm. The compressive strength and elastic modulus of the HA ceramic were comparable to human cortical bone, especially the good fatigue strength overcame brittleness of traditional sintered HA ceramics. Cell attachment experiment also demonstrated that the ceramics had a good cytocompatibility.

Magnetic Nanoparticles: Surface Effects and Properties Related to Biomedicine Applications

PubMed Central

Issa, Bashar; Obaidat, Ihab M.; Albiss, Borhan A.; Haik, Yousef

2013-01-01

Due to finite size effects, such as the high surface-to-volume ratio and different crystal structures, magnetic nanoparticles are found to exhibit interesting and considerably different magnetic properties than those found in their corresponding bulk materials. These nanoparticles can be synthesized in several ways (e.g., chemical and physical) with controllable sizes enabling their comparison to biological organisms from cells (10–100 μm), viruses, genes, down to proteins (3–50 nm). The optimization of the nanoparticles’ size, size distribution, agglomeration, coating, and shapes along with their unique magnetic properties prompted the application of nanoparticles of this type in diverse fields. Biomedicine is one of these fields where intensive research is currently being conducted. In this review, we will discuss the magnetic properties of nanoparticles which are directly related to their applications in biomedicine. We will focus mainly on surface effects and ferrite nanoparticles, and on one diagnostic application of magnetic nanoparticles as magnetic resonance imaging contrast agents. PMID:24232575

Effect of catalyst concentration on size, morphology and optical properties of silica nanoparticles

NASA Astrophysics Data System (ADS)

Arora, Ekta; Ritu, Kumar, Sacheen; Kumar, Dinesh

2016-05-01

Today, nanomaterials play a key role in various fields such as electronics, aerospace, pharmaceuticals and biomedical because of their unique physical, chemical and biological properties which are different from bulk materials. Nano sized silica particles have gained the prominent position in scientific research and have wide applications. The sol-gel method is the best method to synthesize silica nanoparticles because of its potential to produce monodispersed with narrow size distribution at mild conditions. The silica nanoparticles were obtained by hydrolysis of tetraethyl orthosilicate (TEOS) in ethanol act as solvent. The synthesized nanoparticles were characterized by Field Emission Scanning electron Microscope (FE-SEM), UV Spectrometer. The smallest size of silica particles is around 150nm examined by using FE-SEM. The optical properties and band structure was analyzed using UV-visible spectroscopy which is found to be increase by reducing the size of particles. Concentration effect of catalyst on the size, morphology and optical properties were analyzed.

Effect of catalyst concentration on size, morphology and optical properties of silica nanoparticles

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

Arora, Ekta; Ritu,; Kumar, Sacheen, E-mail: sacheen3@gmail.com

2016-05-06

Today, nanomaterials play a key role in various fields such as electronics, aerospace, pharmaceuticals and biomedical because of their unique physical, chemical and biological properties which are different from bulk materials. Nano sized silica particles have gained the prominent position in scientific research and have wide applications. The sol-gel method is the best method to synthesize silica nanoparticles because of its potential to produce monodispersed with narrow size distribution at mild conditions. The silica nanoparticles were obtained by hydrolysis of tetraethyl orthosilicate (TEOS) in ethanol act as solvent. The synthesized nanoparticles were characterized by Field Emission Scanning electron Microscope (FE-SEM),more » UV Spectrometer. The smallest size of silica particles is around 150nm examined by using FE-SEM. The optical properties and band structure was analyzed using UV-visible spectroscopy which is found to be increase by reducing the size of particles. Concentration effect of catalyst on the size, morphology and optical properties were analyzed.« less

Binaries in Transneptunian Resonances: Evidence for Slow Migration of Neptune?

NASA Technical Reports Server (NTRS)

Noll, Keith

2012-01-01

A distinguishing feature of trans neptunian objects (TNO) is the high fraction that arc binary. This is particularly true for the Cold Classicals (CC), objects in lowe and low i orbits concentrated between the 3:2 and 2: 1 mean-motion resonances. CCs have other physical markers: red colors, high albedos, and equal-mass binaries. The CCs appear to be a coherent and physically distinct population of planetesimals that has survived to the present with their physical properties relatively unaltered. Their spatial concentration between 39.4 and 47.7 AU has made identification of the CCs as a physical group possible. However, objects that started out as CCs arc almost certainly 1101 limited to this one dynamical niche. We can, therefore, use the measurable physical properties of CCs as tracers of Neptune-driven dynamical mixing in the Kuiper Belt. As Neptune migrated, its mean-motion resonances preceded it into the planetesimal disk. The efficiency of capture into mean motion resonances depends on the smoothness of Neptune's migration and the local population available to be captured. The two strongest resonances, the 3:2 at 39.4 AU and 2: 1 at 47.7 AU, straddle the core repository of the physically distinct CCs, providing a unique opportunity to test the details of Neptune's migration. Smooth migration should result in a measurable difference between the 3:2 and 2:1 with low inclination 2:1s having a red, binary population mirroring that of the CC itself while the 3:2 will be less contaminated. Alternative models with rapid migration would generate a more homogeneous result.

Comparing two botulinum toxin type A formulations using manufacturers' product summaries.

PubMed

Wenzel, R; Jones, D; Borrego, J A

2007-08-01

Because of the unique pharmacology and clinical versatility of botulinum toxin (BoNT), particularly BoNT serotype A (BoNTA), a need exists for discussion of the current data on similarities and differences between two BoNTA products, BOTOX and Dysport. We compared the physiochemical and pharmacological properties of BOTOX and Dysport using information from the Summary of Product Characteristics (SmPC) documents from a number of countries around the world. Our analysis based on the SmPC documents demonstrated distinct differences in physical characteristics, breadth of approved indications, dosing and administration, and the incidence and severity of adverse events. BOTOX and Dysport are not bioequivalent. Many of the differences between BOTOX and Dysport discussed within are probably related to the differences in their physical characteristics.

Using Model Helicopters for Meteorological Observations in Support of Tornado Forecasting

NASA Astrophysics Data System (ADS)

Harrison, William; Roscoe, Bryan; Schafer, David; Bluestein, Howard; Lary, David

2012-10-01

In order to gain a better understanding of the physical factors involved in tornadogenesis, a complete 3-D profile of winds, temperature, and humidity in the forward-flank and rear-flank gust front regions in supercells is required. Conventional methods of making comparative measurements in and around storms are very limited. Measurements that comprehensively profile the boundary layer winds and thermodynamics are valuable but rare. A better understanding of the physical properties in these boundary layers will improve forecasts and increase warning times in affected areas. Remote-controlled model helicopters are a uniquely qualified platform for this application, allowing us to fully profile these boundary layers. Our system will consist of a swarm of autonomous acrobatic helicopters, each outfitted with temperature, pressure, humidity, and wind speed sensors.

Functionalization-induced changes in the structural and physical properties of amorphous polyaniline: a first-principles and molecular dynamics study.

PubMed

Chen, X P; Liang, Q H; Jiang, J K; Wong, Cell K Y; Leung, Stanley Y Y; Ye, H Y; Yang, D G; Ren, T L

2016-02-09

In this paper, we present a first-principles and molecular dynamics study to delineate the functionalization-induced changes in the local structure and the physical properties of amorphous polyaniline. The results of radial distribution function (RDF) demonstrate that introducing -SO3(-)Na(+) groups at phenyl rings leads to the structural changes in both the intrachain and interchain ordering of polyaniline at shorter distances (≤5 Å). An unique RDF feature in 1.8-2.1 Å regions is usually observed in both the interchain and intrachain RDF profiles of the -SO3(-)Na(+) substituted polymer (i.e. Na-SPANI). Comparative studies of the atom-atom pairs, bond structures, torsion angles and three-dimensional structures show that EB-PANI has much better intrachain ordering than that of Na-SPANI. In addition, investigation of the band gap, density of states (DOS), and absorption spectra indicates that the derivatization at ring do not substantially alter the inherent electronic properties but greatly change the optical properties of polyaniline. Furthermore, the computed diffusion coefficient of water in Na-SPANI is smaller than that of EB-PANI. On the other hand, the Na-SPANI shows a larger density than that of EB-PANI. The computed RDF profiles, band gaps, absorption spectra, and diffusion coefficients are in quantitative agreement with the experimental data.

Ant colony optimisation inversion of surface and borehole magnetic data under lithological constraints

NASA Astrophysics Data System (ADS)

Liu, Shuang; Hu, Xiangyun; Liu, Tianyou; Xi, Yufei; Cai, Jianchao; Zhang, Henglei

2015-01-01

The ant colony optimisation algorithm has successfully been used to invert for surface magnetic data. However, the resolution of the distributions of the recovered physical property for deeply buried magnetic sources is not generally very high because of geophysical ambiguities. We use three approaches to deal with this problem. First, the observed surface magnetic data are taken together with the three-component borehole magnetic anomalies to recover the distributions of the physical properties. This cooperative inversion strategy improves the resolution of the inversion results in the vertical direction. Additionally, as the ant colony tours the discrete nodes, we force it to visit the nodes with physical properties that agree with the drilled lithologies. These lithological constraints reduce the non-uniqueness of the inversion problem. Finally, we also implement a K-means cluster analysis for the distributions of the magnetic cells after each iteration, in order to separate the distributions of magnetisation intensity instead of concentrating the distribution in a single area. We tested our method using synthetic data and found that all tests returned favourable results. In the case study of the Mengku iron-ore deposit in northwest China, the recovered distributions of magnetisation are in good agreement with the locations and shapes of the magnetite orebodies as inferred by drillholes. Uncertainty analysis shows that the ant colony algorithm is robust in the presence of noise and that the proposed approaches significantly improve the quality of the inversion results.

Advances in 2D boron nitride nanostructures: nanosheets, nanoribbons, nanomeshes, and hybrids with graphene.

PubMed

Lin, Yi; Connell, John W

2012-11-21

The recent surge in graphene research has stimulated interest in the investigation of various 2-dimensional (2D) nanomaterials. Among these materials, the 2D boron nitride (BN) nanostructures are in a unique position. This is because they are the isoelectric analogs to graphene structures and share very similar structural characteristics and many physical properties except for the large band gap. The main forms of the 2D BN nanostructures include nanosheets (BNNSs), nanoribbons (BNNRs), and nanomeshes (BNNMs). BNNRs are essentially BNNSs with narrow widths in which the edge effects become significant; BNNMs are also variations of BNNSs, which are supported on certain metal substrates where strong interactions and the lattice mismatch between the substrate and the nanosheet result in periodic shallow regions on the nanosheet surface. Recently, the hybrids of 2D BN nanostructures with graphene, in the form of either in-plane hybrids or inter-plane heterolayers, have also drawn much attention. In particular, the BNNS-graphene heterolayer architectures are finding important electronic applications as BNNSs may serve as excellent dielectric substrates or separation layers for graphene electronic devices. In this article, we first discuss the structural basics, spectroscopic signatures, and physical properties of the 2D BN nanostructures. Then, various top-down and bottom-up preparation methodologies are reviewed in detail. Several sections are dedicated to the preparation of BNNRs, BNNMs, and BNNS-graphene hybrids, respectively. Following some more discussions on the applications of these unique materials, the article is concluded with a summary and perspectives of this exciting new field.

Biomimetic Photonic Crystals based on Diatom Algae Frustules

NASA Astrophysics Data System (ADS)

Mishler, Jonathan; Alverson, Andrew; Herzog, Joseph

2015-03-01

Diatom algae are unicellular, photosynthetic microorganisms with a unique external shell known as a frustule. Frustules, which are composed of amorphous silica, exhibit a unique periodic nano-patterning, distinguishing diatoms from other types of phytoplankton. Diatoms have been studied for their distinctive optical properties due to their resemblance of photonic crystals. In this regard, diatoms are not only considered for their applications as photonic crystals, but also for their use as biomimetic templates for artificially fabricated photonic crystals. Through the examination and measurement of the physical characteristics of many scanning electron microscope (SEM) images of diatom frustules, a biomimetic photonic crystal derived from diatom frustules can be recreated and modeled with the finite element method. In this approach, the average geometries of the diatom frustules are used to recreate a 2-dimensional photonic crystal, after which the electric field distribution and optical transmission through the photonic crystal are both measured. The optical transmission is then compared to the transmission spectra of a regular hexagonal photonic crystal, revealing the effects of diatom geometry on their optical properties. Finally, the dimensions of the photonic crystal are parametrically swept, allowing for further control over the transmission of light through the photonic crystal.

Does the cerebellum initiate movement?

PubMed

Thach, W T

2014-02-01

Opinion is divided on what the exact function of the cerebellum is. Experiments are summarized that support the following views: (1) the cerebellum is a combiner of multiple movement factors; (2) it contains anatomically fixed permanent focal representation of individual body parts (muscles and segments) and movement modes (e.g., vestibular driven vs. cognitive driven); (3) it contains flexible changing representations/memory of physical properties of the body parts including muscle strength, segment inertia, joint viscosity, and segmental interaction torques (dynamics); (4) it contains mechanisms for learning and storage of the properties in item no. 3 through trial-and-error practice; (5) it provides for linkage of body parts, motor modes, and motordynamics via the parallel fiber system; (6) it combines and integrates the many factors so as to initiate coordinated movements of the many body parts; (7) it is thus enabled to play the unique role of initiating coordinated movements; and (8) this unique causative role is evidenced by the fact that: (a) electrical stimulation of the cerebellum can initiate compound coordinated movements; (b) in naturally initiated compound movements, cerebellar discharge precedes that in downstream target structures such as motor cerebral cortex; and (c) cerebellar ablation abolishes the natural production of compound movements in the awake alert individuals.

Theory of the magnetic skyrmion glass

NASA Astrophysics Data System (ADS)

Hoshino, Shintaro; Nagaosa, Naoto

2018-01-01

Skyrmions and skyrmion crystal (SkX) discovered in chiral magnets show unique physical properties due to their nontrivial topology such as the stability against the annihilation and the motion driven by the ultralow current density, which can be advantageous for the device applications such as magnetic memories. Especially, the chiral dynamics, i.e., the velocity perpendicular to the force acting on a skyrmion, is a key to avoid the impurity potential and enhances its mobility. However, the collective pinning of SkX occurs by the disorder, which is crucial for its low energy properties. Here we study theoretically the low energy dynamics of SkX in the presence of disorder effects in terms of replica field theory, and reveal nonreciprocal collective modes and their electromagnetic responses along the direction of the external magnetic field. The physical quantities such as the relaxation rate of μ SR /NMR and the pinning frequency show a dramatic change associated with the topological phase transition from the helical state to SkX. These results provide a firm basis to explore the glassy state of SkX.

Mango kernel fat fractions as potential healthy food ingredients: A review.

PubMed

Jin, Jun; Jin, Qingzhe; Akoh, Casimir C; Wang, Xingguo

2018-01-16

Mango kernel fat (MKF) has been reported to have high functional and nutritional potential. However, its application in food industry has not been fully explored or developed. In this review, the chemical compositions, physical properties and potential health benefits of MKF are described. MKF is a unique fat consisting of 28.9-65.0% of 1,3-distearoyl-2-oleoyl-glycerol with excellent oxidative stability index (58.8-85.2 h at 110 °C), making the fat and its fractions suitable for use as high-value added food ingredients such as cocoa butter alternatives, trans-free shortenings, and a source of natural antioxidants (e.g., sterol, tocopherol and squalene). Unfortunately, the long period of dehydration of mango kernels at hot temperature results in the hydrolysis of triacylglycerols. The high levels of hydrolysates (mainly free fatty acids and diacylglycerols) limit the application of MKF in manufacturing these food ingredients. It is suggested that the physico-chemical and functional properties of MKF could be further improved through moderated refining (e.g., degumming and physical deacidification), fractionation, and interesterification.

Ground state, collective mode, phase soliton and vortex in multiband superconductors.

PubMed

Lin, Shi-Zeng

2014-12-10

This article reviews theoretical and experimental work on the novel physics in multiband superconductors. Multiband superconductors are characterized by multiple superconducting energy gaps in different bands with interaction between Cooper pairs in these bands. The discovery of prominent multiband superconductors MgB2 and later iron-based superconductors, has triggered enormous interest in multiband superconductors. The most recently discovered superconductors exhibit multiband features. The multiband superconductors possess novel properties that are not shared with their single-band counterpart. Examples include: the time-reversal symmetry broken state in multiband superconductors with frustrated interband couplings; the collective oscillation of number of Cooper pairs between different bands, known as the Leggett mode; and the phase soliton and fractional vortex, which are the main focus of this review. This review presents a survey of a wide range of theoretical exploratory and experimental investigations of novel physics in multiband superconductors. A vast amount of information derived from these studies is shown to highlight unusual and unique properties of multiband superconductors and to reveal the challenges and opportunities in the research on the multiband superconductivity.

Baseline assessment of physical characteristics, aquatic biota, and selected water-quality properties at the reach and mesohabitat scale for three stream reaches in the Big Cypress Basin, northeastern Texas, 2010-11

USGS Publications Warehouse

Braun, Christopher L.; Moring, James B.

2013-01-01

The U.S. Geological Survey (USGS), in cooperation with the Northeast Texas Municipal Water District and the Texas Commission on Environmental Quality, did a baseline assessment in 2010-11 of physical characteristics and selected aquatic biota (fish and mussels) collected at the mesohabitat scale for three stream reaches in the Big Cypress Basin in northeastern Texas for which environmental flows have been prescribed. Mesohabitats are visually distinct units of habitat within the stream with unique depth, velocity, slope, substrate, and cover. Mesohabitats in reaches of Big Cypress, Black Cypress, and Little Cypress Bayous were evaluated to gain an understanding of how fish communities and mussel populations varied by habitat. Selected water-quality properties were also measured in isolated pools in Black Cypress and Little Cypress. All of the data were collected in the context of the prescribed environmental flows. The information acquired during the study will support the long-term monitoring of biota in relation to the prescribed environmental flows.

Diamond-like carbon prepared by pulsed laser deposition with ion bombardment: physical properties

NASA Astrophysics Data System (ADS)

Písařík, P.; Mikšovský, J.; Remsa, J.; Zemek, J.; Tolde, Z.; Jelínek, M.

2018-01-01

Diamond-like carbon (DLC) and titanium-doped DLC thin films were prepared by unique hybrid system consisting of pulsed laser deposition, ion source (bombardment) and magnetron sputtering. The influence of deposition parameters (ion energies, deposition pressures and magnetron power) on composition and physical properties was studied. Composition and sp 3/ sp 2 ratio were determined by XPS. sp 3/ sp 2 ratio was in the range from 1.4 to 2.2 for undoped DLC and from 3.4 to 4.8 for Ti-DLC. AFM showed that the layers were smooth, but with small amounts of random droplets. The measurements of the contact angle and determination of surface free energy were made for water, diiodomethane and ethylene glycol. Hardness and reduced Young's modulus varied from 20 to 31 GPa and from 182 to 276 GPa, respectively. Film adhesion was determined by scratch test; L C3 reached 23 N for DLC and 27 N for TiDLC. Optimization of sp 3/ sp 2 ratio, hardness and adhesion to biomedical alloys will advance the DLC coatings usability in the field of implantology.

Ce3+-Doped garnet phosphors: composition modification, luminescence properties and applications.

PubMed

Xia, Zhiguo; Meijerink, Andries

2017-01-03

Garnets have the general formula of A 3 B 2 C 3 O 12 and form a wide range of inorganic compounds, occurring both naturally (gemstones) and synthetically. Their physical and chemical properties are closely related to the structure and composition. In particular, Ce 3+ -doped garnet phosphors have a long history and are widely applied, ranging from flying spot cameras, lasers and phosphors in fluorescent tubes to more recent applications in white light LEDs, as afterglow materials and scintillators for medical imaging. Garnet phosphors are unique in their tunability of the luminescence properties through variations in the {A}, [B] and (C) cation sublattice. The flexibility in phosphor composition and the tunable luminescence properties rely on design and synthesis strategies for new garnet compositions with tailor-made luminescence properties. It is the aim of this review to discuss the variation in luminescence properties of Ce 3+ -doped garnet materials in relation to the applications. This review will provide insight into the relation between crystal chemistry and luminescence for the important class of Ce 3+ -doped garnet phosphors. It will summarize previous research on the structural design and optical properties of garnet phosphors and also discuss future research opportunities in this field.

Green materials for sustainable development

NASA Astrophysics Data System (ADS)

Purwasasmita, B. S.

2017-03-01

Sustainable development is an integrity of multidiscipline concept combining ecological, social and economic aspects to construct a liveable human living system. The sustainable development can be support through the development of green materials. Green materials offers a unique characteristic and properties including abundant in nature, less toxic, economically affordable and versatility in term of physical and chemical properties. Green materials can be applied for a numerous field in science and technology applications including for energy, building, construction and infrastructures, materials science and engineering applications and pollution management and technology. For instance, green materials can be developed as a source for energy production. Green materials including biomass-based source can be developed as a source for biodiesel and bioethanol production. Biomass-based materials also can be transformed into advanced functionalized materials for advanced bio-applications such as the transformation of chitin into chitosan which further used for biomedicine, biomaterials and tissue engineering applications. Recently, cellulose-based material and lignocellulose-based materials as a source for the developing functional materials attracted the potential prospect for biomaterials, reinforcing materials and nanotechnology. Furthermore, the development of pigment materials has gaining interest by using the green materials as a source due to their unique properties. Eventually, Indonesia as a large country with a large biodiversity can enhance the development of green material to strengthen our nation competitiveness and develop the materials technology for the future.

Nanocomposites of polymer and inorganic nanoparticles for optical and magnetic applications

PubMed Central

Li, Shanghua; Meng Lin, Meng; Toprak, Muhammet S.; Kim, Do Kyung; Muhammed, Mamoun

2010-01-01

This article provides an up-to-date review on nanocomposites composed of inorganic nanoparticles and the polymer matrix for optical and magnetic applications. Optical or magnetic characteristics can change upon the decrease of particle sizes to very small dimensions, which are, in general, of major interest in the area of nanocomposite materials. The use of inorganic nanoparticles into the polymer matrix can provide high-performance novel materials that find applications in many industrial fields. With this respect, frequently considered features are optical properties such as light absorption (UV and color), and the extent of light scattering or, in the case of metal particles, photoluminescence, dichroism, and so on, and magnetic properties such as superparamagnetism, electromagnetic wave absorption, and electromagnetic interference shielding. A general introduction, definition, and historical development of polymer–inorganic nanocomposites as well as a comprehensive review of synthetic techniques for polymer–inorganic nanocomposites will be given. Future possibilities for the development of nanocomposites for optical and magnetic applications are also introduced. It is expected that the use of new functional inorganic nano-fillers will lead to new polymer–inorganic nanocomposites with unique combinations of material properties. By careful selection of synthetic techniques and understanding/exploiting the unique physics of the polymeric nanocomposites in such materials, novel functional polymer–inorganic nanocomposites can be designed and fabricated for new interesting applications such as optoelectronic and magneto-optic applications. PMID:22110855

Biopharmaceutics and Therapeutic Potential of Engineered Nanomaterials

PubMed Central

Liang, Xing-Jie; Chen, Chunying; Zhao, Yuliang; Jia, Lee; Wang, Paul C.

2009-01-01

Engineered nanomaterials are at the leading edge of the rapidly developing nanosciences and are founding an important class of new materials with specific physicochemical properties different from bulk materials with the same compositions. The potential for nanomaterials is rapidly expanding with novel applications constantly being explored in different areas. The unique size-dependent properties of nanomaterials make them very attractive for pharmaceutical applications. Investigations of physical, chemical and biological properties of engineered nanomaterials have yielded valuable information. Cytotoxic effects of certain engineered nanomaterials towards malignant cells form the basis for one aspect of nanomedicine. It is inferred that size, three dimensional shape, hydrophobicity and electronic configurations make them an appealing subject in medicinal chemistry. Their unique structure coupled with immense scope for derivatization forms a base for exciting developments in therapeutics. This review article addresses the fate of absorption, distribution, metabolism and excretion (ADME) of engineered nanoparticles in vitro and in vivo. It updates the distinctive methodology used for studying the biopharmaceutics of nanoparticles. This review addresses the future potential and safety concerns and genotoxicity of nanoparticle formulations in general. It particularly emphasizes the effects of nanoparticles on metabolic enzymes as well as the parenteral or inhalation administration routes of nanoparticle formulations. This paper illustrates the potential of nanomedicine by discussing biopharmaceutics of fullerene derivatives and their suitability for diagnostic and therapeutic purposes. Future direction is discussed as well. PMID:18855608

The Physical Fitness of Adolescents with Cerebral Palsy. Project UNIQUE II. Final Report.

ERIC Educational Resources Information Center

Winnick, Joseph P.; Short, Francis X.

The final report describes a 2-year project of the State University of New York, College at Brockport, to study the physical fitness of nonretarded and retarded adolescents with cerebral palsy. The UNIQUE Physical Fitness Test was administered to 203 cerebral palsied adolescents throughout the United States and from segregated and nonsegregated…

Exchange Bias Effects in Iron Oxide-Based Nanoparticle Systems

DOE PAGES

Phan, Manh-Huong; Alonso, Javier; Khurshid, Hafsa; ...

2016-11-23

The exploration of exchange bias (EB) on the nanoscale provides a novel approach to improving the anisotropic properties of magnetic nanoparticles for prospective applications in nanospintronics and nanomedicine. However, the physical origin of EB is not fully understood. Recent advances in chemical synthesis provide a unique opportunity to explore EB in a variety of iron oxide-based nanostructures ranging from core/shell to hollow and hybrid composite nanoparticles. Experimental and atomistic Monte Carlo studies have shed light on the roles of interface and surface spins in these nanosystems. This review paper aims to provide a thorough understanding of the EB and relatedmore » phenomena in iron oxide-based nanoparticle systems, knowledge of which is essential to tune the anisotropic magnetic properties of exchange-coupled nanoparticle systems for potential applications.« less

Recent advances in biocompatible semiconductor nanocrystals for immunobiological applications.

PubMed

Nanda, Sitansu Sekhar; Kim, Min Jik; Kim, Kwangmeyung; Papaefthymiou, Georgia C; Selvan, Subramanian Tamil; Yi, Dong Kee

2017-11-01

Quantum confinement in inorganic semiconductor nanocrystals produces brightly luminescent nanoparticles endowed with unique photo-physical properties, such as tunable optical properties. These have found widespread applications in nanotechnology. The ability to render such nanostructures biocompatible, while maintaining their tunable radiation in the visible range of the electromagnetic spectrum, renders them appropriate for bio-applications. Promising in vitro and in vivo diagnostic applications have been demonstrated, such as fluorescence-based detection of biological interactions, single molecule tracking, multiplexing and immunoassaying. In particular, these fluorescent inorganic semiconductor nanocrystals, generally known as quantum dots, have the potential of remarkable immunobiological applications. This review focuses on the current status of biocompatible quantum dots and their applications in immunobiology - immunosensing, immunofluorescent imaging and immunotherapy. Copyright © 2017 Elsevier B.V. All rights reserved.

Creating With Carbon

NASA Technical Reports Server (NTRS)

2003-01-01

A subsidiary of SI Diamond Technology, Inc., Applied Nanotech, of Austin, Texas, is creating a buzz among various technology firms and venture capital groups interested in the company s progressive research on carbon-related field emission devices, including carbon nanotubes, filaments of pure carbon less than one ten-thousandth the width of human hair. Since their discovery in 1991, carbon nanotubes have gained considerable attention due to their unique physical properties. For example, a single perfect carbon nanotube can range from 10 to 100 times stronger than steel, per unit weight. Recent studies also indicate that the nanotubes may be the best heat-conducting material in existence. These properties, combined with the ease of growing thin films or nanotubes by a variety of deposition techniques, make the carbon-based material one of the most desirable for cold field emission cathodes.

Two main and a new type rare earth elements in Mg alloys: A review

NASA Astrophysics Data System (ADS)

Kong, Linghang

2017-09-01

Magnesium (Mg) alloys stand for the lightest structure engineering materials. Moreover, the strengthening of Mg alloys in ductility, toughness and corrosion predominates their wide applications. With adding rare earth elements in Mg, the mechanical properties will be improved remarkably, especially their plasticity and strength. A brief overview of the addition of rare earth elements for Mg alloys is shown. The basic mechanisms of strengthening Mg alloys with rare earth elements are reviewed, including the solid solution strengthening, grain refinement and long period stacking ordered (LPSO) phase. Furthermore, the available rare earth elements are summarized by type, chemical or physical effects and other unique properties. Finally, some challenge problems that the research is facing and future expectations of ra-re-earth Mg alloys are stated and discussed.

Nonlinear Optics with 2D Layered Materials.

PubMed

Autere, Anton; Jussila, Henri; Dai, Yunyun; Wang, Yadong; Lipsanen, Harri; Sun, Zhipei

2018-06-01

2D layered materials (2DLMs) are a subject of intense research for a wide variety of applications (e.g., electronics, photonics, and optoelectronics) due to their unique physical properties. Most recently, increasing research efforts on 2DLMs are projected toward the nonlinear optical properties of 2DLMs, which are not only fascinating from the fundamental science point of view but also intriguing for various potential applications. Here, the current state of the art in the field of nonlinear optics based on 2DLMs and their hybrid structures (e.g., mixed-dimensional heterostructures, plasmonic structures, and silicon/fiber integrated structures) is reviewed. Several potential perspectives and possible future research directions of these promising nanomaterials for nonlinear optics are also presented. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bifunctional Carbon-Dot-WS2 Nanorods for Photothermal Therapy and Cell Imaging.

PubMed

Nandi, Sukhendu; Bhunia, Susanta Kumar; Zeiri, Leila; Pour, Maayan; Nachman, Iftach; Raichman, Daniel; Lellouche, Jean-Paul Moshe; Jelinek, Raz

2017-01-18

Multifunctional nanoparticles have attracted significant interest as biomedical vehicles, combining diagnostic, imaging, and therapeutic properties. We describe herein the construction of new nanoparticle conjugates comprising WS 2 nanorods (NRs) coupled to fluorescent carbon dots (C-dots). We show that the WS 2 -C-dot hybrids integrate the unique physical properties of the two species, specifically the photothermal activity of the WS 2 NRs upon irradiation with near-infrared (NIR) light and the excitation-dependent luminescence emission of the C-dots. The WS 2 -C-dot NRs have been shown to be non-cytotoxic and have been successfully employed for multicolour cell imaging and targeted cell killing under NIR irradiation, pointing to their potential utilization as effective therapeutic vehicles. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bipolar doping and band-gap anomalies in delafossite transparent conductive oxides.

PubMed

Nie, Xiliang; Wei, Su-Huai; Zhang, S B

2002-02-11

Doping wide-gap materials p type is highly desirable but often difficult. This makes the recent discovery of p-type delafossite oxides, CuM(III)O2, very attractive. The CuM(III)O2 also show unique and unexplained physical properties: Increasing band gap from M(III) = Al,Ga, to In, not seen in conventional semiconductors. The largest gap CuInO2 can be mysteriously doped both n and p type but not the smaller gaps CuAlO2 and CuGaO2. Here, we show that both properties are results of a large disparity between the fundamental gap and the apparent optical gap, a finding that could lead to a breakthrough in the study of bipolarly dopable wide-gap semiconductor oxides.

Exchange Bias Effects in Iron Oxide-Based Nanoparticle Systems

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

Phan, Manh-Huong; Alonso, Javier; Khurshid, Hafsa

The exploration of exchange bias (EB) on the nanoscale provides a novel approach to improving the anisotropic properties of magnetic nanoparticles for prospective applications in nanospintronics and nanomedicine. However, the physical origin of EB is not fully understood. Recent advances in chemical synthesis provide a unique opportunity to explore EB in a variety of iron oxide-based nanostructures ranging from core/shell to hollow and hybrid composite nanoparticles. Experimental and atomistic Monte Carlo studies have shed light on the roles of interface and surface spins in these nanosystems. This review paper aims to provide a thorough understanding of the EB and relatedmore » phenomena in iron oxide-based nanoparticle systems, knowledge of which is essential to tune the anisotropic magnetic properties of exchange-coupled nanoparticle systems for potential applications.« less

Multifunctional Quantum Dots for Personalized Medicine

PubMed Central

Zrazhevskiy, Pavel; Gao, Xiaohu

2009-01-01

Successes in biomedical research and state-of-the-art medicine have undoubtedly improved the quality of life. However, a number of diseases, such as cancer, immunodeficiencies, and neurological disorders, still evade conventional diagnostic and therapeutic approaches. A transformation towards personalized medicine may help to combat these diseases. For this, identification of disease molecular fingerprints and their association with prognosis and targeted therapy must become available. Quantum dots (QDs), semiconductor nanocrystals with unique photo-physical properties, represent a novel class of fluorescence probes to address many of the needs of personalized medicine. This review outlines the properties of QDs that make them a suitable platform for advancing personalized medicine, examines several proof-of-concept studies showing utility of QDs for clinically relevant applications, and discusses current challenges in introducing QDs into clinical practice. PMID:20161004

Exchange Bias Effects in Iron Oxide-Based Nanoparticle Systems

PubMed Central

Phan, Manh-Huong; Alonso, Javier; Khurshid, Hafsa; Lampen-Kelley, Paula; Chandra, Sayan; Stojak Repa, Kristen; Nemati, Zohreh; Das, Raja; Iglesias, Óscar; Srikanth, Hariharan

2016-01-01

The exploration of exchange bias (EB) on the nanoscale provides a novel approach to improving the anisotropic properties of magnetic nanoparticles for prospective applications in nanospintronics and nanomedicine. However, the physical origin of EB is not fully understood. Recent advances in chemical synthesis provide a unique opportunity to explore EB in a variety of iron oxide-based nanostructures ranging from core/shell to hollow and hybrid composite nanoparticles. Experimental and atomistic Monte Carlo studies have shed light on the roles of interface and surface spins in these nanosystems. This review paper aims to provide a thorough understanding of the EB and related phenomena in iron oxide-based nanoparticle systems, knowledge of which is essential to tune the anisotropic magnetic properties of exchange-coupled nanoparticle systems for potential applications. PMID:28335349

Coexistence of superconductivity and antiferromagnetism in (Li0.8Fe0.2)OHFeSe.

PubMed

Lu, X F; Wang, N Z; Wu, H; Wu, Y P; Zhao, D; Zeng, X Z; Luo, X G; Wu, T; Bao, W; Zhang, G H; Huang, F Q; Huang, Q Z; Chen, X H

2015-03-01

Iron selenide superconductors exhibit a number of unique characteristics that are helpful for understanding the mechanism of superconductivity in high-Tc iron-based superconductors more generally. However, in the case of AxFe2Se2 (A = K, Rb, Cs), the presence of an intergrown antiferromagnetic insulating phase makes the study of the underlying physics problematic. Moreover, FeSe-based systems intercalated with alkali metal ions, NH3 molecules or organic molecules are extremely sensitive to air, which prevents the further investigation of their physical properties. It is therefore desirable to find a stable and easily accessible FeSe-based superconductor to study its physical properties in detail. Here, we report the synthesis of an air-stable material, (Li0.8Fe0.2)OHFeSe, which remains superconducting at temperatures up to ~40 K, by means of a novel hydrothermal method. The crystal structure is unambiguously determined by a combination of X-ray and neutron powder diffraction and nuclear magnetic resonance. Moreover, antiferromagnetic order is shown to coexist with superconductivity. This synthetic route opens a path for exploring superconductivity in other related systems, and confirms the appeal of iron selenides as a platform for understanding superconductivity in iron pnictides more broadly.

The hidden ecological resource of andic soils in mountain ecosystems: evidence from Italy

NASA Astrophysics Data System (ADS)

Terribile, Fabio; Iamarino, Michela; Langella, Giuliano; Manna, Piero; Mileti, Florindo Antonio; Vingiani, Simona; Basile, Angelo

2018-01-01

Andic soils have unique morphological, physical, and chemical properties that induce both considerable soil fertility and great vulnerability to land degradation. Moreover, they are the most striking mineral soils in terms of large organic C storage and long C residence time. This is especially related to the presence of poorly crystalline clay minerals and metal-humus complexes. Recognition of andic soils is then very important.Here we attempt to show, through a combined analysis of 35 sampling points chosen in accordance to specific physical and vegetation rules, that some andic soils have an utmost ecological importance.More specifically, in Italian non-volcanic mountain ecosystems ( > 600 m a.s.l.) combining low slope (< 21 %) and highly active green biomass (high NDVI values) and in agreement to recent findings, we found the widespread occurrence of andic soils having distinctive physical and hydrological properties including low bulk density and remarkably high water retention. Most importantly, we report a demonstration of the ability of these soils to affect ecosystem functions by analysing their influence on the timescale acceleration of photosynthesis estimated by NDVI measurements.Our results are hoped to be a starting point for better understanding of the ecological importance of andic soils and also possibly to better consider pedological information in C balance calculations.

Carbon-based layer-by-layer nanostructures: from films to hollow capsules

NASA Astrophysics Data System (ADS)

Hong, Jinkee; Han, Jung Yeon; Yoon, Hyunsik; Joo, Piljae; Lee, Taemin; Seo, Eunyong; Char, Kookheon; Kim, Byeong-Su

2011-11-01

Over the past years, the layer-by-layer (LbL) assembly has been widely developed as one of the most powerful techniques to prepare multifunctional films with desired functions, structures and morphologies because of its versatility in the process steps in both material and substrate choices. Among various functional nanoscale objects, carbon-based nanomaterials, such as carbon nanotubes and graphene sheets, are promising candidates for emerging science and technology with their unique physical, chemical, and mechanical properties. In particular, carbon-based functional multilayer coatings based on the LbL assembly are currently being actively pursued as conducting electrodes, batteries, solar cells, supercapacitors, fuel cells and sensor applications. In this article, we give an overview on the use of carbon materials in nanostructured films and capsules prepared by the LbL assembly with the aim of unraveling the unique features and their applications of carbon multilayers prepared by the LbL assembly.

Excitons in atomically thin 2D semiconductors and their applications

DOE PAGES

Xiao, Jun; Zhao, Mervin; Wang, Yuan; ...

2017-01-01

The research on emerging layered two-dimensional (2D) semiconductors, such as molybdenum disulfide (MoS 2), reveals unique optical properties generating significant interest. Experimentally, these materials were observed to host extremely strong light-matter interactions as a result of the enhanced excitonic effect in two dimensions. Thus, understanding and manipulating the excitons are crucial to unlocking the potential of 2D materials for future photonic and optoelectronic devices. Here in this review, we unravel the physical origin of the strong excitonic effect and unique optical selection rules in 2D semiconductors. In addition, control of these excitons by optical, electrical, as well as mechanical meansmore » is examined. Finally, the resultant devices such as excitonic light emitting diodes, lasers, optical modulators, and coupling in an optical cavity are overviewed, demonstrating how excitons can shape future 2D optoelectronics.« less

Structural Transitions and Energy Landscape for Cowpea Chlorotic Mottle Virus Capsid Mechanics from Nanomanipulation in Vitro and in Silico

NASA Astrophysics Data System (ADS)

Kononova, Olga; Snijder, Joost; Brasch, Melanie; Cornelissen, Jeroen; Dima, Ruxandra I.; Marx, Kenneth A.; Wuite, Gijs J. L.; Roos, Wouter H.; Barsegov, Valeri

2013-10-01

Physical properties of capsids of plant and animal viruses are important factors in capsid self-assembly, survival of viruses in the extracellular environment, and their cell infectivity. Virus shells can have applications as nanocontainers and delivery vehicles in biotechnology and medicine. Combined AFM experiments and computational modeling on sub-second timescales of the indentation nanomechanics of Cowpea Chlorotic Mottle Virus (CCMV) capsid show that the capsid's physical properties are dynamic and local characteristics of the structure, which depend on the magnitude and geometry of mechanical input. Surprisingly, under large deformations the CCMV capsid transitions to the collapsed state without substantial local structural alterations. The enthalpy change in this deformation state dH = 11.5 - 12.8 MJ/mol is mostly due to large-amplitude out-of-plane excitations, which contribute to the capsid bending, and the entropy change TdS = 5.1 - 5.8 MJ/mol is mostly due to coherent in-plane rearrangements of protein chains, which result in the capsid stiffening. Dynamic coupling of these modes defines the extent of elasticity and reversibility of capsid mechanical deformation. This emerging picture illuminates how unique physico-chemical properties of protein nanoshells help define their structure and morphology, and determine their viruses' biological function.

Bacteriophage-associated gene transfer in pneumococcus: transduction or pseudotransduction?

PubMed Central

Porter, R D; Shoemaker, N B; Rampe, G; Guild, W R

1979-01-01

Lysates of pneumococcal phage PG24 transferred genes from one host to another in a process with many of the properties of generalized transduction, in that the host genes were packaged in DNase-resistant particles that closely resembled infectious phage in physical properties, adsorbed to the recipient cells like phage, and were inhibited by antisera to the phage and by trypsin. However, phage processes did not complete the transfer of host DNA as they did phage DNA. Instead, gene transfer required development of competence and entry of the host DNA by the endonuclease-dependent pathway used for transforming and transfecting DNA. This process often occurred on the assay plate hours after adsorption of the particles to the cells, and the transfer was DNase sensitive if challenged at this time. Phenotypic expression was therefore also delayed. The product of entry was like that in transformation, a single strand of DNA that integrates by formation of a hex-sensitive donor-recipient heteroduplex. Whether this gene transfer process is unique to this system or is only the first one described is not clear. The term "pseudotransduction" may be useful in calling attention to its unexpected features. The DNA of PG24 phage has anomalous physical properties reflecting unusual bases. Images PMID:33154

Hydrogel formulation determines cell fate of fetal and adult neural progenitor cells

PubMed Central

Wagner, Jennifer L.; Shandas, Robin; Bjugstad, Kimberly B.

2014-01-01

Hydrogels provide a unique tool for neural tissue engineering. These materials can be customized for certain functions, i.e. to provide cell/drug delivery or act as a physical scaffold. Unfortunately, hydrogel complexities can negatively impact their biocompatibility, resulting in unintended consequences. These adverse effects may be combated with a better understanding of hydrogel chemical, physical, and mechanical properties, and how these properties affect encapsulated neural cells. We defined the polymerization and degradation rates and compressive moduli of 25 hydrogels formulated from different concentrations of hyaluronic acid (HA) and poly(ethylene glycol) (PEG). Changes in compressive modulus were driven primarily by the HA concentration. The in vitro biocompatibility of fetal-derived (fNPC) and adult-derived (aNPC) neural progenitor cells was dependent on hydrogel formulation. Acute survival of fNPC benefited from hydrogel encapsulation. NPC differentiation was divergent: fNPC differentiated into mostly glial cells, compared with neuronal differentiation of aNPC. Differentiation was influenced in part by the hydrogel mechanical properties. This study indicates that there can be a wide range of HA and PEG hydrogels compatible with NPC. Additionally, this is the first study comparing hydrogel encapsulation of NPC derived from different aged sources, with data suggesting that fNPC and aNPC respond dissimilarly within the same hydrogel formulation. PMID:24141109

Interpretations of family size distributions: The Datura example

NASA Astrophysics Data System (ADS)

Henych, Tomáš; Holsapple, Keith A.

2018-04-01

Young asteroid families are unique sources of information about fragmentation physics and the structure of their parent bodies, since their physical properties have not changed much since their birth. Families have different properties such as age, size, taxonomy, collision severity and others, and understanding the effect of those properties on our observations of the size-frequency distribution (SFD) of family fragments can give us important insights into the hypervelocity collision processes at scales we cannot achieve in our laboratories. Here we take as an example the very young Datura family, with a small 8-km parent body, and compare its size distribution to other families, with both large and small parent bodies, and created by both catastrophic and cratering formation events. We conclude that most likely explanation for the shallower size distribution compared to larger families is a more pronounced observational bias because of its small size. Its size distribution is perfectly normal when its parent body size is taken into account. We also discuss some other possibilities. In addition, we study another common feature: an offset or "bump" in the distribution occurring for a few of the larger elements. We hypothesize that it can be explained by a newly described regime of cratering, "spall cratering", which controls the majority of impact craters on the surface of small asteroids like Datura.

Effects of 1-Alkyl-3-Methylimidazolium Nitrate on Soil Physical and Chemical Properties and Microbial Biomass.

PubMed

Zhou, Tongtong; Wang, Jun; Ma, Zhiqiang; Du, Zhongkun; Zhang, Cheng; Zhu, Lusheng; Wang, Jinhua

2018-05-01

Ionic liquids (ILs), also called room temperature ILs, are widely applied in many fields on the basis of their unique physical and chemical properties. However, numerous ILs may be released into and gradually accumulate in the environment due to their extensive use and absolute solubility. The effects of 1-alkyl-3-methylimidazolium nitrate ([C n mim]NO 3 , n = 4, 6, 8) on soil pH, conductivity, cation exchange capacity, microbial biomass carbon, and microbial biomass nitrogen were examined at the doses of 1, 10, and 100 mg/kg on days 10, 20, 30, and 40. The results demonstrated that the soil pH decreased and the conductivity increased with increasing IL doses. No significant differences were observed in the soil cation-exchange capacity. All three of the tested ILs decreased the soil microbial biomass carbon and nitrogen. Additionally, there were few differences among the ILs with different alkyl chain lengths on the tested indicators except for the microbial biomass nitrogen. The present study addressed a gap in the literature regarding the effects of the aforementioned ILs with different alkyl side chains on the physicochemical properties of soil, and the results could provide the basic data for future studies on their toxicity to soil organisms, such as earthworms and soil microbes.

Phase Behavior and Physical Properties of New Biobased Ionic Liquid Crystals.

PubMed

Toledo Hijo, Ariel A C; Maximo, Guilherme J; Costa, Mariana C; Cunha, Rosiane L; Pereira, Jorge F B; Kurnia, Kiki A; Batista, Eduardo A C; Meirelles, Antonio J A

2017-04-13

Protic ionic liquids (PILs) have emerged as promising compounds and attracted the interest of the industry and the academy community, due to their easy preparation and unique properties. In the context of green chemistry, the use of biocompounds, such as fatty acids, for their synthesis could disclose a possible alternative way to produce ILs with a low or nontoxic effect and, consequently, expanding their applicability in biobased processes or in the development of bioproducts. This work addressed efforts to a better comprehension of the complex solid-[liquid crystal]-liquid thermodynamic equilibrium of 20 new PILs synthesized by using fatty acids commonly found in vegetable oils, as well as their rheological profile and self-assembling ability. The work revealed that their phase equilibrium and physical properties are significantly impacted by the structure of the ions used for their synthesis. The use of unsaturated fatty acids and bis(2-hydroxyethyl)ammonium for the synthesis of these biobased ILs led to a drastic decreasing of their melting temperatures. Also, the longest alkyl chain fatty acids promoted higher self-assembling and more stable mesophases. Besides their sustainable appeal, the marked high viscosity, non-Newtonian profile, and very low critical micellar concentration values of the PIL crystals here disclosed make them interesting renewable compounds with potential applications as emulsifiers, stabilizers, thickeners, or biolubricants.

Model-free data analysis for source separation based on Non-Negative Matrix Factorization and k-means clustering (NMFk)

NASA Astrophysics Data System (ADS)

Vesselinov, V. V.; Alexandrov, B.

2014-12-01

The identification of the physical sources causing spatial and temporal fluctuations of state variables such as river stage levels and aquifer hydraulic heads is challenging. The fluctuations can be caused by variations in natural and anthropogenic sources such as precipitation events, infiltration, groundwater pumping, barometric pressures, etc. The source identification and separation can be crucial for conceptualization of the hydrological conditions and characterization of system properties. If the original signals that cause the observed state-variable transients can be successfully "unmixed", decoupled physics models may then be applied to analyze the propagation of each signal independently. We propose a new model-free inverse analysis of transient data based on Non-negative Matrix Factorization (NMF) method for Blind Source Separation (BSS) coupled with k-means clustering algorithm, which we call NMFk. NMFk is capable of identifying a set of unique sources from a set of experimentally measured mixed signals, without any information about the sources, their transients, and the physical mechanisms and properties controlling the signal propagation through the system. A classical BSS conundrum is the so-called "cocktail-party" problem where several microphones are recording the sounds in a ballroom (music, conversations, noise, etc.). Each of the microphones is recording a mixture of the sounds. The goal of BSS is to "unmix'" and reconstruct the original sounds from the microphone records. Similarly to the "cocktail-party" problem, our model-freee analysis only requires information about state-variable transients at a number of observation points, m, where m > r, and r is the number of unknown unique sources causing the observed fluctuations. We apply the analysis on a dataset from the Los Alamos National Laboratory (LANL) site. We identify and estimate the impact and sources are barometric pressure and water-supply pumping effects. We also estimate the location of the water-supply pumping wells based on the available data. The possible applications of the NMFk algorithm are not limited to hydrology problems; NMFk can be applied to any problem where temporal system behavior is observed at multiple locations and an unknown number of physical sources are causing these fluctuations.

Novel soy protein wound dressings with controlled antibiotic release: mechanical and physical properties.

PubMed

Peles, Zachi; Zilberman, Meital

2012-01-01

Naturally derived materials are becoming widely used in the biomedical field. Soy protein has advantages over various types of natural proteins employed for biomedical applications due to its low price, non-animal origin and relatively long storage time and stability. In the current study soy protein isolate (SPI) was investigated as a matrix for wound dressing applications. The antibiotic drug gentamicin was incorporated into the matrix for local controlled release and, thus, protection against bacterial infection. Homogeneous yellowish films were cast from aqueous solutions. After cross-linking they combined high tensile strength and Young's modulus with the desired ductility. The plasticizer type, cross-linking agent and method of cross-linking were found to strongly affect the tensile properties of the SPI films. Selected SPI films were tested for relevant physical properties and the gentamicin release profile. The cross-linking method affected the degree of water uptake and the weight loss profile. The water vapor transmission rate of the films was in the desired range for wound dressings (∼2300 g m(-2) day(-1)) and was not affected by the cross-linking method. The gentamicin release profile exhibited a moderate burst effect followed by a decreasing release rate which was maintained for at least 4 weeks. Diffusion was the dominant release mechanism of gentamicin from cross-linked SPI films. Appropriate selection of the process parameters yielded SPI wound dressings with the desired mechanical and physical properties and drug release behavior to protect against bacterial infection. These unique structures are thus potentially useful as burn and ulcer dressings. Copyright © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Development and characterization of food-grade tracers for the global grain tracing and recall system.

PubMed

Lee, Kyung-Min; Armstrong, Paul R; Thomasson, J Alex; Sui, Ruixiu; Casada, Mark; Herrman, Timothy J

2010-10-27

Tracing grain from the farm to its final processing destination as it moves through multiple grain-handling systems, storage bins, and bulk carriers presents numerous challenges to existing record-keeping systems. This study examines the suitability of coded caplets to trace grain, in particular, to evaluate methodology to test tracers' ability to withstand the rigors of a commercial grain handling and storage systems as defined by physical properties using measurement technology commonly applied to assess grain hardness and end-use properties. Three types of tracers to dispense into bulk grains for tracing the grain back to its field of origin were developed using three food-grade substances [processed sugar, pregelatinized starch, and silicified microcrystalline cellulose (SMCC)] as a major component in formulations. Due to a different functionality of formulations, the manufacturing process conditions varied for each tracer type, resulting in unique variations in surface roughness, weight, dimensions, and physical and spectroscopic properties before and after coating. The applied two types of coating [pregelatinized starch and hydroxypropylmethylcellulose (HPMC)] using an aqueous coating system containing appropriate plasticizers showed uniform coverage and clear coating. Coating appeared to act as a barrier against moisture penetration, to protect against mechanical damage of the surface of the tracers, and to improve the mechanical strength of tracers. The results of analysis of variance (ANOVA) tests showed the type of tracer, coating material, conditioning time, and a theoretical weight gain significantly influenced the morphological and physical properties of tracers. Optimization of these factors needs to be pursued to produce desirable tracers with consistent quality and performance when they flow with bulk grains throughout the grain marketing channels.

Narrow-gap physical vapour deposition synthesis of ultrathin SnS1-xSex (0 ≤ x ≤ 1) two-dimensional alloys with unique polarized Raman spectra and high (opto)electronic properties.

PubMed

Gao, Wei; Li, Yongtao; Guo, Jianhua; Ni, Muxun; Liao, Ming; Mo, Haojie; Li, Jingbo

2018-05-10

Here we report ultrathin SnS1-xSex alloyed nanosheets synthesized via a narrow-gap physical vapour deposition approach. The SnS1-xSex alloy presents a uniform quadrangle shape with a lateral size of 5-80 μm and a thickness of several nanometers. Clear orthorhombic symmetries and unique in-plane anisotropic properties of the 2D alloyed nanosheets were found with the help of X-ray diffraction, high resolution transmission electron microscopy and polarized Raman spectroscopy. Moreover, 2D alloyed field-effect transistors were fabricated, exhibiting a unipolar p-type semiconductor behavior. This study also provided a lesson that the thickness of the alloyed channels played the major role in the current on/off ratio, and the high ratio of 2.10 × 102 measured from a large ultrathin SnS1-xSex device was two orders of magnitude larger than that of previously reported SnS, SnSe nanosheet based transistors because of the capacitance shielding effect. Obviously enhanced Raman peaks were also found in the thinner nanosheets. Furthermore, the ultrathin SnS0.5Se0.5 based photodetector showed a highest responsivity of 1.69 A W-1 and a short response time of 40 ms under illumination of a 532 nm laser from 405 to 808 nm. Simultaneously, the corresponding highest external quantum efficiency of 392% and detectivity of 3.96 × 104 Jones were also achieved. Hopefully, the narrow-gap synthesis technique provides us with an improved strategy to obtain large ultrathin 2D nanosheets which may tend to grow into thicker ones for stronger interlayer van der Waals forces, and the enhanced physical and (opto)electrical performances in the obtained ultrathin SnS1-xSex alloyed nanosheets prove their great potential in the future applications for versatile devices.

Is there life after teaching physics?

NASA Astrophysics Data System (ADS)

Martin, David S.

2016-01-01

Why an article about retirement in the primary journal for the teachers of introductory physics courses? There is the all-too-common reason that little or no thought may have been given to an impending near certainty. But just as physics teachers have a unique place in their schools, they have equally unique perspectives and talents that can be put to fruitful application in retirement.

Two dimensional layered materials: First-principle investigation

NASA Astrophysics Data System (ADS)

Tang, Youjian

Two-dimensional layered materials have emerged as a fascinating research area due to their unique physical and chemical properties, which differ from those of their bulk counterparts. Some of these unique properties are due to carriers and transport being confined to 2 dimensions, some are due to lattice symmetry, and some arise from their large surface area, gateability, stackability, high mobility, spin transport, or optical accessibility. How to modify the electronic and magnetic properties of two-dimensional layered materials for desirable long-term applications or fundamental physics is the main focus of this thesis. We explored the methods of adsorption, intercalation, and doping as ways to modify two-dimensional layered materials, using density functional theory as the main computational methodology. Chapter 1 gives a brief review of density functional theory. Due to the difficulty of solving the many-particle Schrodinger equation, density functional theory was developed to find the ground-state properties of many-electron systems through an examination of their charge density, rather than their wavefunction. This method has great application throughout the chemical and material sciences, such as modeling nano-scale systems, analyzing electronic, mechanical, thermal, optical and magnetic properties, and predicting reaction mechanisms. Graphene and transition metal dichalcogenides are arguably the two most important two-dimensional layered materials in terms of the scope and interest of their physical properties. Thus they are the main focus of this thesis. In chapter 2, the structure and electronic properties of graphene and transition metal dichalcogenides are described. Alkali adsorption onto the surface of bulk graphite and metal intecalation into transition metal dichalcogenides -- two methods of modifying properties through the introduction of metallic atoms into layered systems -- are described in chapter 2. Chapter 3 presents a new method of tuning the electronic properties of 2D materials: resonant physisorption. An example is given for adsorption of polycyclic aromatic hydrocarbon molecules onto graphene. The energy levels of these molecules were fine tuned to make them resonate with the graphene Fermi level, thus enhancing the strength of their effect on the graphene electronic structure. Chapter 4 develops the idea of coupling two distinct surface adsorption systems across a suspended atomically thin membrane. We examine a system of dual-sided adsorption of potassium onto a graphene membrane. The sequence of adsorption patterns predicted undergoes a striking devil's staircase of intermediate coverage fractions as the difference in adsorbate chemical potential between the two sides of the membrane varies. Chapter 5 is devoted to magnetic and band structure engineering of transition metal dichalcogenides through introduction of magnetic atoms into the lattice. Semiconducting transition metal dichalcogenide systems such as MoS2 and WS2 have band gaps suitable for electronic and optoelectronic applications, but are not magnetic. By intercalating and doping in a carefully designed stoichiometric ratio that precisely controls the occupation and relative placement of the dopant and host levels, we can convert a semiconducting transition metal dichalcogenide system into a half-metal or -- more surprisingly -- a half-semiconductor, where the conduction band is fully spin polarized and the energy scale for magnetism is the band gap.

A frozen super-Earth orbiting a star at the bottom of the main sequence

NASA Astrophysics Data System (ADS)

Kubas, D.; Beaulieu, J. P.; Bennett, D. P.; Cassan, A.; Cole, A.; Lunine, J.; Marquette, J. B.; Dong, S.; Gould, A.; Sumi, T.; Batista, V.; Fouqué, P.; Brillant, S.; Dieters, S.; Coutures, C.; Greenhill, J.; Bond, I.; Nagayama, T.; Udalski, A.; Pompei, E.; Nürnberger, D. E. A.; Le Bouquin, J. B.

2012-04-01

Context. Microlensing is a unique method to probe low mass exoplanets beyond the snow line. However, the scientific potential of the new microlensing planet discovery is often unfulfilled due to lack of knowledge of the properties of the lens and source stars. The discovery light curve of the super Earth MOA-2007-BLG-192Lb suffers from significant degeneracies that limit what can be inferred about its physical properties. Aims: High resolution adaptive optics images allow us to solve this problem by resolving the microlensing target from all unrelated background stars, yielding the unique determination of magnified source and lens fluxes. This estimation permits the solution of our microlens model for the mass of the planet and its host and their physical projected separation. Methods: We observed the microlensing event MOA-2007-BLG-192 at high angular resolution in JHKs with the NACO adaptive optics system on the VLT while the object was still amplified by a factor 1.23 and then at baseline 18 months later. We analyzed and calibrated the NACO photometry in the standard 2MASS system in order to accurately constrain the source and the lens star fluxes. Results: We detect light from the host star of MOA-2007-BLG-192Lb, which significantly reduces the uncertainties in its characteristics as compared to earlier analyses. We find that MOA-2007-BLG-192L is most likely a very low mass late type M-dwarf (0.084-0.012+0.015 M⊙) at a distance of 660-70+100 pc orbited by a 3.2-1.8+5.2 M⊕ super-Earth at 0.66-0.22+0.51 AU. We then discuss the properties of this cold planetary system. Based on observations under ESO Prog.IDs: 279.C-5044(A) and 383-C.0495(A).

Biphenyl liquid crystalline epoxy resin as a low-shrinkage resin-based dental restorative nanocomposite.

PubMed

Hsu, Sheng-Hao; Chen, Rung-Shu; Chang, Yuan-Ling; Chen, Min-Huey; Cheng, Kuo-Chung; Su, Wei-Fang

2012-11-01

Low-shrinkage resin-based photocurable liquid crystalline epoxy nanocomposite has been investigated with regard to its application as a dental restoration material. The nanocomposite consists of an organic matrix and an inorganic reinforcing filler. The organic matrix is made of liquid crystalline biphenyl epoxy resin (BP), an epoxy resin consisting of cyclohexylmethyl-3,4-epoxycyclohexanecarboxylate (ECH), the photoinitiator 4-octylphenyl phenyliodonium hexafluoroantimonate and the photosensitizer champhorquinone. The inorganic filler is silica nanoparticles (∼70-100 nm). The nanoparticles were modified by an epoxy silane of γ-glycidoxypropyltrimethoxysilane to be compatible with the organic matrix and to chemically bond with the organic matrix after photo curing. By incorporating the BP liquid crystalline (LC) epoxy resin into conventional ECH epoxy resin, the nanocomposite has improved hardness, flexural modulus, water absorption and coefficient of thermal expansion. Although the incorporation of silica filler may dilute the reinforcing effect of crystalline BP, a high silica filler content (∼42 vol.%) was found to increase the physical and chemical properties of the nanocomposite due to the formation of unique microstructures. The microstructure of nanoparticle embedded layers was observed in the nanocomposite using scanning and transmission electron microscopy. This unique microstructure indicates that the crystalline BP and nanoparticles support each other and result in outstanding mechanical properties. The crystalline BP in the LC epoxy resin-based nanocomposite was partially melted during exothermic photopolymerization, and the resin expanded via an order-to-disorder transition. Thus, the post-gelation shrinkage of the LC epoxy resin-based nanocomposite is greatly reduced, ∼50.6% less than in commercialized methacrylate resin-based composites. This LC epoxy nanocomposite demonstrates good physical and chemical properties and good biocompatibility, comparable to commercialized composites. The results indicate that this novel LC nanocomposite is worthy of development and has potential for further applications in clinical dentistry. Copyright © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Nanomedicine applications in orthopedic medicine: state of the art

PubMed Central

Mazaheri, Mozhdeh; Eslahi, Niloofar; Ordikhani, Farideh; Tamjid, Elnaz; Simchi, Abdolreza

2015-01-01

The technological and clinical need for orthopedic replacement materials has led to significant advances in the field of nanomedicine, which embraces the breadth of nanotechnology from pharmacological agents and surface modification through to regulation and toxicology. A variety of nanostructures with unique chemical, physical, and biological properties have been engineered to improve the functionality and reliability of implantable medical devices. However, mimicking living bone tissue is still a challenge. The scope of this review is to highlight the most recent accomplishments and trends in designing nanomaterials and their applications in orthopedics with an outline on future directions and challenges. PMID:26451110

Why new neutron detector materials must replace helium-3

NASA Astrophysics Data System (ADS)

Hurd, Alan J.; Kouzes, Richard T.

2014-10-01

Helium-3 has such unique physical and nuclear properties that to a physicist it seems appalling the isotope was once indiscriminately released to the atmosphere as a waste gas. Not gravitationally bound to our planet, a He-3 atom is effectively lost to the human race once released. Consequently, when a confluence of independent factors in national security and research in the last decade created a "custody battle" over this scarce isotope, an intense search for substitutes and alternative technologies ensued for various applications. This Focus Point of EPJ Plus is dedicated to neutron detector alternatives.

Oxidative Stress and Mitochondrial Activation as the Main Mechanisms Underlying Graphene Toxicity against Human Cancer Cells

PubMed Central

2016-01-01

Due to the development of nanotechnology graphene and graphene-based nanomaterials have attracted the most attention owing to their unique physical, chemical, and mechanical properties. Graphene can be applied in many fields among which biomedical applications especially diagnostics, cancer therapy, and drug delivery have been arousing a lot of interest. Therefore it is essential to understand better the graphene-cell interactions, especially toxicity and underlying mechanisms for proper use and development. This review presents the recent knowledge concerning graphene cytotoxicity and influence on different cancer cell lines. PMID:26649139

Nanomedicine applications in orthopedic medicine: state of the art.

PubMed

Mazaheri, Mozhdeh; Eslahi, Niloofar; Ordikhani, Farideh; Tamjid, Elnaz; Simchi, Abdolreza

2015-01-01

The technological and clinical need for orthopedic replacement materials has led to significant advances in the field of nanomedicine, which embraces the breadth of nanotechnology from pharmacological agents and surface modification through to regulation and toxicology. A variety of nanostructures with unique chemical, physical, and biological properties have been engineered to improve the functionality and reliability of implantable medical devices. However, mimicking living bone tissue is still a challenge. The scope of this review is to highlight the most recent accomplishments and trends in designing nanomaterials and their applications in orthopedics with an outline on future directions and challenges.

Polyhedral Oligomeric Silsesquioxane (POSS)-Containing Polymer Nanocomposites

PubMed Central

Ayandele, Ebunoluwa; Sarkar, Biswajit; Alexandridis, Paschalis

2012-01-01

Hybrid materials with superior structural and functional properties can be obtained by incorporating nanofillers into polymer matrices. Polyhedral oligomeric silsesquioxane (POSS) nanoparticles have attracted much attention recently due to their nanometer size, the ease of which these particles can be incorporated into polymeric materials and the unique capability to reinforce polymers. We review here the state of POSS-containing polymer nanocomposites. We discuss the influence of the incorporation of POSS into polymer matrices via chemical cross-linking or physical blending on the structure of nanocomposites, as affected by surface functional groups, and the POSS concentration. PMID:28348318

The Higgs mechanism and the origin of mass

NASA Astrophysics Data System (ADS)

Djouadi, Abdelhak

2012-06-01

The Higgs mechanism plays a key role in the physics of elementary particles: in the context of the Standard Model, the theory which describes in a unified framework the electromagnetic, weak and strong nuclear interactions, it allows for the generation of particle masses while preserving the fundamental symmetries of the theory. This mechanism predicts the existence of a new type of particle, the scalar Higgs boson, with unique characteristics. The detection of this particle and the study of its fundamental properties is a major goal of high-energy particle colliders, such as the CERN Large Hadron Collider or LHC.

The Higgs Mechanism and the Orogin of Mass

NASA Astrophysics Data System (ADS)

Djouadi, Abdelhak

The Higgs mechanism plays a key role in the physics of elementary particles: in the context of the Standard Model, the theory which, describes in a unified framework the electromagnetic, weak, and strong nuclear interactions, it allows for the generation of particle masses while preserving the fundamental symmetries of the theory. This mechanism predicts the existence of a new type of particle, the scalar Higgs boson, with unique characteristics. The detection of this particle and the study of its fundamental properties is a major goal of high-energy particle colliders, such as the CERN Large Hadron Collider or LHC.

Flow microreactor synthesis in organo-fluorine chemistry

PubMed Central

Nagaki, Aiichiro

2013-01-01

Summary Organo-fluorine compounds are the substances of considerable interest in various industrial fields due to their unique physical and chemical properties. Despite increased demand in wide fields of science, synthesis of fluoro-organic compounds is still often faced with problems such as the difficulties in handling of fluorinating reagents and in controlling of chemical reactions. Recently, flow microreactor synthesis has emerged as a new methodology for producing chemical substances with high efficiency. This review outlines the successful examples of synthesis and reactions of fluorine-containing molecules by the use of flow microreactor systems to overcome long-standing problems in fluorine chemistry. PMID:24367443

Flow microreactor synthesis in organo-fluorine chemistry.

PubMed

Amii, Hideki; Nagaki, Aiichiro; Yoshida, Jun-Ichi

2013-12-05

Organo-fluorine compounds are the substances of considerable interest in various industrial fields due to their unique physical and chemical properties. Despite increased demand in wide fields of science, synthesis of fluoro-organic compounds is still often faced with problems such as the difficulties in handling of fluorinating reagents and in controlling of chemical reactions. Recently, flow microreactor synthesis has emerged as a new methodology for producing chemical substances with high efficiency. This review outlines the successful examples of synthesis and reactions of fluorine-containing molecules by the use of flow microreactor systems to overcome long-standing problems in fluorine chemistry.

Integrating the glioblastoma microenvironment into engineered experimental models

PubMed Central

Xiao, Weikun; Sohrabi, Alireza; Seidlits, Stephanie K

2017-01-01

Glioblastoma (GBM) is the most lethal cancer originating in the brain. Its high mortality rate has been attributed to therapeutic resistance and rapid, diffuse invasion – both of which are strongly influenced by the unique microenvironment. Thus, there is a need to develop new models that mimic individual microenvironmental features and are able to provide clinically relevant data. Current understanding of the effects of the microenvironment on GBM progression, established experimental models of GBM and recent developments using bioengineered microenvironments as ex vivo experimental platforms that mimic the biochemical and physical properties of GBM tumors are discussed. PMID:28883992

Titanium: light, strong, and white

USGS Publications Warehouse

Woodruff, Laurel; Bedinger, George

2013-01-01

Titanium (Ti) is a strong silver-gray metal that is highly resistant to corrosion and is chemically inert. It is as strong as steel but 45 percent lighter, and it is twice as strong as aluminum but only 60 percent heavier. Titanium dioxide (TiO2) has a very high refractive index, which means that it has high light-scattering ability. As a result, TiO2 imparts whiteness, opacity, and brightness to many products. ...Because of the unique physical properties of titanium metal and the whiteness provided by TiO2, titanium is now used widely in modern industrial societies.

Novel symmetries in Christ-Lee model

NASA Astrophysics Data System (ADS)

Kumar, R.; Shukla, A.

2016-07-01

We demonstrate that the gauge-fixed Lagrangian of the Christ-Lee model respects four fermionic symmetries, namely; (anti-)BRST symmetries, (anti-)co-BRST symmetries within the framework of BRST formalism. The appropriate anticommutators amongst the fermionic symmetries lead to a unique bosonic symmetry. It turns out that the algebra obeyed by the symmetry transformations (and their corresponding conserved charges) is reminiscent of the algebra satisfied by the de Rham cohomological operators of differential geometry. We also provide the physical realizations of the cohomological operators in terms of the symmetry properties. Thus, the present model provides a simple model for the Hodge theory.

Nanomaterials-Based Optical Techniques for the Detection of Acetylcholinesterase and Pesticides

PubMed Central

Xia, Ning; Wang, Qinglong; Liu, Lin

2015-01-01

The large amount of pesticide residues in the environment is a threat to global health by inhibition of acetylcholinesterase (AChE). Biosensors for inhibition of AChE have been thus developed for the detection of pesticides. In line with the rapid development of nanotechnology, nanomaterials have attracted great attention and have been intensively studied in biological analysis due to their unique chemical, physical and size properties. The aim of this review is to provide insight into nanomaterial-based optical techniques for the determination of AChE and pesticides, including colorimetric and fluorescent assays and surface plasmon resonance. PMID:25558991

A Multigrasp Hand Prosthesis for Providing Precision and Conformal Grasps

PubMed Central

Bennett, Daniel A.; Dalley, Skyler A.; Truex, Don; Goldfarb, Michael

2015-01-01

This paper presents the design of an anthropomorphic prosthetic hand that incorporates four motor units in a unique configuration to explicitly provide both precision and conformal grasp capability. The paper describes the design of the hand prosthesis, and additionally describes the design of an embedded control system located in the palm of the hand that enables self-contained control of hand movement. Following the design description, the paper provides experimental characterizations of hand performance, including digit force capability, bandwidth of digit movement, physical properties such as size and mass, and electrical power measurements during activities of daily living. PMID:26167111

High Power Helicon Plasma Source for Plasma Processing

NASA Astrophysics Data System (ADS)

Prager, James; Ziemba, Timothy; Miller, Kenneth E.

2015-09-01

Eagle Harbor Technologies (EHT), Inc. is developing a high power helicon plasma source. The high power nature and pulsed neutral gas make this source unique compared to traditional helicon source. These properties produce a plasma flow along the magnetic field lines, and therefore allow the source to be decoupled from the reaction chamber. Neutral gas can be injected downstream, which allows for precision control of the ion-neutral ratio at the surface of the sample. Although operated at high power, the source has demonstrated very low impurity production. This source has applications to nanoparticle productions, surface modification, and ionized physical vapor deposition.

Influence of nanomaterials on stem cell differentiation: designing an appropriate nanobiointerface

PubMed Central

Ilie, Ioana; Ilie, Razvan; Mocan, Teodora; Bartos, Dana; Mocan, Lucian

2012-01-01

During the last decade, due to advances in functionalization chemistry, novel nanobiomaterials with applications in tissue engineering and regenerative medicine have been developed. These novel materials with their unique physical and chemical properties are bioactive hierarchical structures that hold great promise for future development of human tissues. Thus, various nanomaterials are currently being intensively explored in the directed differentiation of stem cells, the design of novel bioactive scaffolds, and new research avenues towards tissue regeneration. This paper illustrates the latest achievements in the applications of nanotechnology in tissue engineering in the field of regenerative medicine. PMID:22619557

Magnetic Resonance Imaging of Gel-cast Ceramic Composites

DOE R&D Accomplishments Database

Dieckman, S. L.; Balss, K. M.; Waterfield, L. G.; Jendrzejczyk, J. A.; Raptis, A. C.

1997-01-16

Magnetic resonance imaging (MRI) techniques are being employed to aid in the development of advanced near-net-shape gel-cast ceramic composites. MRI is a unique nondestructive evaluation tool that provides information on both the chemical and physical properties of materials. In this effort, MRI imaging was performed to monitor the drying of porous green-state alumina - methacrylamide-N.N`-methylene bisacrylamide (MAM-MBAM) polymerized composite specimens. Studies were performed on several specimens as a function of humidity and time. The mass and shrinkage of the specimens were also monitored and correlated with the water content.

Rare earth element and rare metal inventory of central Asia

USGS Publications Warehouse

Mihalasky, Mark J.; Tucker, Robert D.; Renaud, Karine; Verstraeten, Ingrid M.

2018-03-06

Rare earth elements (REE), with their unique physical and chemical properties, are an essential part of modern living. REE have enabled development and manufacture of high-performance materials, processes, and electronic technologies commonly used today in computing and communications, clean energy and transportation, medical treatment and health care, glass and ceramics, aerospace and defense, and metallurgy and chemical refining. Central Asia is an emerging REE and rare metals (RM) producing region. A newly compiled inventory of REE-RM-bearing mineral occurrences and delineation of areas-of-interest indicate this region may have considerable undiscovered resources.

Ionic Modification Turns Commercial Rubber into a Self-Healing Material.

PubMed

Das, Amit; Sallat, Aladdin; Böhme, Frank; Suckow, Marcus; Basu, Debdipta; Wiessner, Sven; Stöckelhuber, Klaus Werner; Voit, Brigitte; Heinrich, Gert

2015-09-23

Invented by Charles Goodyear, chemical cross-linking of rubbers by sulfur vulcanization is the only method by which modern automobile tires are manufactured. The formation of these cross-linked network structures leads to highly elastic properties, which substantially reduces the viscous properties of these materials. Here, we describe a simple approach to converting commercially available and widely used bromobutyl rubber (BIIR) into a highly elastic material with extraordinary self-healing properties without using conventional cross-linking or vulcanising agents. Transformation of the bromine functionalities of BIIR into ionic imidazolium bromide groups results in the formation of reversible ionic associates that exhibit physical cross-linking ability. The reversibility of the ionic association facilitates the healing processes by temperature- or stress-induced rearrangements, thereby enabling a fully cut sample to retain its original properties after application of the self-healing process. Other mechanical properties, such as the elastic modulus, tensile strength, ductility, and hysteresis loss, were found to be superior to those of conventionally sulfur-cured BIIR. This simple and easy approach to preparing a commercial rubber with self-healing properties offers unique development opportunities in the field of highly engineered materials, such as tires, for which safety, performance, and longer fatigue life are crucial factors.

Unique environmental effects on physical activity participation: a twin study.

PubMed

Duncan, Glen E; Goldberg, Jack; Noonan, Carolyn; Moudon, Anne Vernez; Hurvitz, Philip; Buchwald, Dedra

2008-04-16

The health benefits of regular physical activity are well established. However, the relative contribution of heritable and environmental factors to physical activity participation remains controversial. Using a cut-point of 60 minutes of total activity per week, data from the GenomEUtwin project revealed consistent genetic influence on physical activity participation in 37,051 twin pairs from seven countries. We hypothesized that the heritability of physical activity participation would be attenuated using the CDC/ACSM recommended minimum threshold of 150 minutes of moderate intensity activity per week. Data were obtained from 1,389 twin pairs from the community-based University of Washington Twin Registry. Twin similarity in physical activity participation using both cut-points was analyzed using tetrachoric correlations and structural equation modeling in all same-sex pairs. Correlations were higher in monozygotic (r(MZ) = 0.43, 95% CI = 0.33-0.54) than dizygotic pairs (r(DZ) = 0.30, 95% CI = 0.12-0.47) using the 60 minute cut-point. However, differences were attenuated using the 150 minute standard (r(MZ) = 0.30, 95% CI = 0.20-0.40; r(DZ) = 0.25, 95% CI = 0.07-0.42). Using the lower cut-point, the best fitting model of twin resemblance only included additive genetics and unique environment, with a heritability of 45%. In contrast, using the higher threshold, the best fitting model included the common and unique environment, with the unique environment contributing 72% of the variance. Unique environment factors provide the strongest influence on physical activity participation at levels recommended for health benefits.

Practical relevance of pattern uniqueness in forensic science.

PubMed

Jayaprakash, Paul T

2013-09-10

Uniqueness being unprovable, it has recently been argued that individualization in forensic science is irrelevant and, probability, as applied for DNA profiles, should be applied for all identifications. Critiques against uniqueness have omitted physical matching, a realistic and tangible individualization that supports uniqueness. Describing case examples illustrating pattern matches including physical matching, it is indicated that individualizations are practically relevant for forensic science as they establish facts on a definitive basis providing firm leads benefitting criminal investigation. As a tenet of forensic identification, uniqueness forms a fundamental paradigm relevant for individualization. Evidence on the indeterministic and stochastic causal pathways of characteristics in patterns available in the related fields of science sufficiently supports the proposition of uniqueness. Characteristics involved in physical matching and matching achieved in patterned evidence existing in the state of nature are not events amenable for counting; instead these are ensemble of visible units occupying the entire pattern area stretching the probability of re-occurrence of a verisimilitude pattern into infinity offering epistemic support to uniqueness. Observational methods are as respectable as instrumental or statistical methods since they are capable of generating results that are tangible and obviously valid as in physical matching. Applying the probabilistic interpretation used for DNA profiles to the other patterns would be unbefitting since these two are disparate, the causal pathways of the events, the loci, in the manipulated DNA profiles being determinable. While uniqueness enables individualizations, it does not vouch for eliminating errors. Instead of dismissing uniqueness and individualization, accepting errors as human or system failures and seeking remedial measures would benefit forensic science practice and criminal investigation. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

MT+, integrating magnetotellurics to determine earth structure, physical state, and processes

USGS Publications Warehouse

Bedrosian, P.A.

2007-01-01

As one of the few deep-earth imaging techniques, magnetotellurics provides information on both the structure and physical state of the crust and upper mantle. Magnetotellurics is sensitive to electrical conductivity, which varies within the earth by many orders of magnitude and is modified by a range of earth processes. As with all geophysical techniques, magnetotellurics has a non-unique inverse problem and has limitations in resolution and sensitivity. As such, an integrated approach, either via the joint interpretation of independent geophysical models, or through the simultaneous inversion of independent data sets is valuable, and at times essential to an accurate interpretation. Magnetotelluric data and models are increasingly integrated with geological, geophysical and geochemical information. This review considers recent studies that illustrate the ways in which such information is combined, from qualitative comparisons to statistical correlation studies to multi-property inversions. Also emphasized are the range of problems addressed by these integrated approaches, and their value in elucidating earth structure, physical state, and processes. ?? Springer Science+Business Media B.V. 2007.

Higgs cosmology

NASA Astrophysics Data System (ADS)

Rajantie, Arttu

2018-01-01

The discovery of the Higgs boson in 2012 and other results from the Large Hadron Collider have confirmed the standard model of particle physics as the correct theory of elementary particles and their interactions up to energies of several TeV. Remarkably, the theory may even remain valid all the way to the Planck scale of quantum gravity, and therefore it provides a solid theoretical basis for describing the early Universe. Furthermore, the Higgs field itself has unique properties that may have allowed it to play a central role in the evolution of the Universe, from inflation to cosmological phase transitions and the origin of both baryonic and dark matter, and possibly to determine its ultimate fate through the electroweak vacuum instability. These connections between particle physics and cosmology have given rise to a new and growing field of Higgs cosmology, which promises to shed new light on some of the most puzzling questions about the Universe as new data from particle physics experiments and cosmological observations become available. This article is part of the Theo Murphy meeting issue `Higgs cosmology'.

Silicon and germanium nanowire electronics: physics of conventional and unconventional transistors

NASA Astrophysics Data System (ADS)

Weber, Walter M.; Mikolajick, Thomas

2017-06-01

Research in the field of electronics of 1D group-IV semiconductor structures has attracted increasing attention over the past 15 years. The exceptional combination of the unique 1D electronic transport properties with the mature material know-how of highly integrated silicon and germanium technology holds the promise of enhancing state-of-the-art electronics. In addition of providing conduction channels that can bring conventional field effect transistors to the uttermost scaling limits, the physics of 1D group IV nanowires endows new device principles. Such unconventional silicon and germanium nanowire devices are contenders for beyond complementary metal oxide semiconductor (CMOS) computing by virtue of their distinct switching behavior and higher expressive value. This review conveys to the reader a systematic recapitulation and analysis of the physics of silicon and germanium nanowires and the most relevant CMOS and CMOS-like devices built from silicon and germanium nanowires, including inversion mode, junctionless, steep-slope, quantum well and reconfigurable transistors.

Probing viscoelastic surfaces with bimodal tapping-mode atomic force microscopy: Underlying physics and observables for a standard linear solid model.

PubMed

Solares, Santiago D

2014-01-01

This paper presents computational simulations of single-mode and bimodal atomic force microscopy (AFM) with particular focus on the viscoelastic interactions occurring during tip-sample impact. The surface is modeled by using a standard linear solid model, which is the simplest system that can reproduce creep compliance and stress relaxation, which are fundamental behaviors exhibited by viscoelastic surfaces. The relaxation of the surface in combination with the complexities of bimodal tip-sample impacts gives rise to unique dynamic behaviors that have important consequences with regards to the acquisition of quantitative relationships between the sample properties and the AFM observables. The physics of the tip-sample interactions and its effect on the observables are illustrated and discussed, and a brief research outlook on viscoelasticity measurement with intermittent-contact AFM is provided.

A fully-automated neural network analysis of AFM force-distance curves for cancer tissue diagnosis

NASA Astrophysics Data System (ADS)

Minelli, Eleonora; Ciasca, Gabriele; Sassun, Tanya Enny; Antonelli, Manila; Palmieri, Valentina; Papi, Massimiliano; Maulucci, Giuseppe; Santoro, Antonio; Giangaspero, Felice; Delfini, Roberto; Campi, Gaetano; De Spirito, Marco

2017-10-01

Atomic Force Microscopy (AFM) has the unique capability of probing the nanoscale mechanical properties of biological systems that affect and are affected by the occurrence of many pathologies, including cancer. This capability has triggered growing interest in the translational process of AFM from physics laboratories to clinical practice. A factor still hindering the current use of AFM in diagnostics is related to the complexity of AFM data analysis, which is time-consuming and needs highly specialized personnel with a strong physical and mathematical background. In this work, we demonstrate an operator-independent neural-network approach for the analysis of surgically removed brain cancer tissues. This approach allowed us to distinguish—in a fully automated fashion—cancer from healthy tissues with high accuracy, also highlighting the presence and the location of infiltrating tumor cells.

DC magnetron sputtered polyaniline-HCl thin films for chemical sensing applications.

PubMed

Menegazzo, Nicola; Boyne, Devon; Bui, Holt; Beebe, Thomas P; Booksh, Karl S

2012-07-03

Thin films of conducting polymers exhibit unique chemical and physical properties that render them integral parts in microelectronics, energy storage devices, and chemical sensors. Overall, polyaniline (PAni) doped in acidic media has shown metal-like electronic conductivity, though exact physical and chemical properties are dependent on the polymer structure and dopant type. Difficulties arising from poor processability render production of doped PAni thin films particularly challenging. In this contribution, DC magnetron sputtering, a physical vapor deposition technique, is applied to the preparation of conductive thin films of PAni doped with hydrochloric acid (PAni-HCl) in an effort to circumvent issues associated with conventional thin film preparation methods. Samples manufactured by the sputtering method are analyzed along with samples prepared by conventional drop-casting. Physical characterization (atomic force microscopy, AFM) confirm the presence of PAni-HCl and show that films exhibit a reduced roughness and potentially pinhole-free coverage of the substrate. Spectroscopic evidence (UV-vis, FT-IR, and X-ray photoelectron spectroscopy (XPS)) suggests that structural changes and loss of conductivity, not uncommon during PAni processing, does occur during the preparation process. Finally, the applicability of sputtered films to gas-phase sensing of NH(3) was investigated with surface plasmon resonance (SPR) spectroscopy and compared to previous contributions. In summary, sputtered PAni-HCl films exhibit quantifiable, reversible behavior upon exposure to NH(3) with a calculated LOD (by method) approaching 0.4 ppm NH(3) in dry air.

Physics considerations in targeted anticancer drug delivery by magnetoelectric nanoparticles

NASA Astrophysics Data System (ADS)

Stimphil, Emmanuel; Nagesetti, Abhignyan; Guduru, Rakesh; Stewart, Tiffanie; Rodzinski, Alexandra; Liang, Ping; Khizroev, Sakhrat

2017-06-01

In regard to cancer therapy, magnetoelectric nanoparticles (MENs) have proven to be in a class of its own when compared to any other nanoparticle type. Like conventional magnetic nanoparticles, they can be used for externally controlled drug delivery via application of a magnetic field gradient and image-guided delivery. However, unlike conventional nanoparticles, due to the presence of a non-zero magnetoelectric effect, MENs provide a unique mix of important properties to address key challenges in modern cancer therapy: (i) a targeting mechanism driven by a physical force rather than antibody matching, (ii) a high-specificity delivery to enhance the cellular uptake of therapeutic drugs across the cancer cell membranes only, while sparing normal cells, (iii) an externally controlled mechanism to release drugs on demand, and (iv) a capability for image guided precision medicine. These properties separate MEN-based targeted delivery from traditional biotechnology approaches and lay a foundation for the complementary approach of technobiology. The biotechnology approach stems from the underlying biology and exploits bioinformatics to find the right therapy. In contrast, the technobiology approach is geared towards using the physics of molecular-level interactions between cells and nanoparticles to treat cancer at the most fundamental level and thus can be extended to all the cancers. This paper gives an overview of the current state of the art and presents an ab initio model to describe the underlying mechanisms of cancer treatment with MENs from the perspective of basic physics.

Microstructure and Properties of Polypropylene/Carbon Nanotube Nanocomposites

PubMed Central

Bikiaris, Dimitrios

2010-01-01

In the last few years, great attention has been paid to the preparation of polypropylene (PP) nanocomposites using carbon nanotubes (CNTs) due to the tremendous enhancement of the mechanical, thermal, electrical, optical and structural properties of the pristine material. This is due to the unique combination of structural, mechanical, electrical, and thermal transport properties of CNTs. However, it is well-known that the properties of polymer-based nanocomposites strongly depend on the dispersion of nanofillers and almost all the discussed properties of PP/CNTs nanocomposites are strongly related to their microstructure. PP/CNTs nanocomposites were, mainly, prepared by melt mixing and in situ polymerization. Young’s modulus, tensile strength and storage modulus of the PP/CNTs nanocomposites can be increased with increasing CNTs content due to the reinforcement effect of CNTs inside the polymer matrix. However, above a certain CNTs content the mechanical properties are reduced due to the CNTs agglomeration. The microstructure of nanocomposites has been studied mainly by SEM and TEM techniques. Furthermore, it was found that CNTs can act as nucleating agents promoting the crystallization rates of PP and the addition of CNTs enhances all other physical properties of PP. The aim of this paper is to provide a comprehensive review of the existing literature related to PP/CNTs nanocomposite preparation methods and properties studies.

Kentucky DOE EPSCoR Program

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

Grulke, Eric; Stencel, John

2011-09-13

The KY DOE EPSCoR Program supports two research clusters. The Materials Cluster uses unique equipment and computational methods that involve research expertise at the University of Kentucky and University of Louisville. This team determines the physical, chemical and mechanical properties of nanostructured materials and examines the dominant mechanisms involved in the formation of new self-assembled nanostructures. State-of-the-art parallel computational methods and algorithms are used to overcome current limitations of processing that otherwise are restricted to small system sizes and short times. The team also focuses on developing and applying advanced microtechnology fabrication techniques and the application of microelectrornechanical systems (MEMS)more » for creating new materials, novel microdevices, and integrated microsensors. The second research cluster concentrates on High Energy and Nuclear Physics. lt connects research and educational activities at the University of Kentucky, Eastern Kentucky University and national DOE research laboratories. Its vision is to establish world-class research status dedicated to experimental and theoretical investigations in strong interaction physics. The research provides a forum, facilities, and support for scientists to interact and collaborate in subatomic physics research. The program enables increased student involvement in fundamental physics research through the establishment of graduate fellowships and collaborative work.« less

Physical View on the Interactions Between Cancer Cells and the Endothelial Cell Lining During Cancer Cell Transmigration and Invasion

NASA Astrophysics Data System (ADS)

Mierke, Claudia T.

There exist many reviews on the biological and biochemical interactions of cancer cells and endothelial cells during the transmigration and tissue invasion of cancer cells. For the malignant progression of cancer, the ability to metastasize is a prerequisite. In particular, this means that certain cancer cells possess the property to migrate through the endothelial lining into blood or lymph vessels, and are possibly able to transmigrate through the endothelial lining into the connective tissue and follow up their invasion path in the targeted tissue. On the molecular and biochemical level the transmigration and invasion steps are well-defined, but these signal transduction pathways are not yet clear and less understood in regards to the biophysical aspects of these processes. To functionally characterize the malignant transformation of neoplasms and subsequently reveal the underlying pathway(s) and cellular properties, which help cancer cells to facilitate cancer progression, the biomechanical properties of cancer cells and their microenvironment come into focus in the physics-of-cancer driven view on the metastasis process of cancers. Hallmarks for cancer progression have been proposed, but they still lack the inclusion of specific biomechanical properties of cancer cells and interacting surrounding endothelial cells of blood or lymph vessels. As a cancer cell is embedded in a special environment, the mechanical properties of the extracellular matrix also cannot be neglected. Therefore, in this review it is proposed that a novel hallmark of cancer that is still elusive in classical tumor biological reviews should be included, dealing with the aspect of physics in cancer disease such as the natural selection of an aggressive (highly invasive) subtype of cancer cells displaying a certain adhesion or chemokine receptor on their cell surface. Today, the physical aspects can be analyzed by using state-of-the-art biophysical methods. Thus, this review will present current cancer research in a different light from a physical point of view with respect to cancer cell mechanics and the special and unique role of the endothelium on cancer cell invasion. The physical view on cancer disease may lead to novel insights into cancer disease and will help to overcome the classical views on cancer. In addition, in this review it will be discussed how physics of cancer can help to reveal and propose the functional mechanism which cancer cells use to invade connective tissue and transmigrate through the endothelium to finally metastasize. Finally, in this review it will be demonstrated how biophysical measurements can be combined with classical analysis approaches of tumor biology. The insights into physical interactions between cancer cells, the endothelium and the microenvironment may help to answer some "old," but still important questions in cancer disease progression.

Physical View on the Interactions Between Cancer Cells and the Endothelial Cell Lining During Cancer Cell Transmigration and Invasion

NASA Astrophysics Data System (ADS)

Mierke, Claudia T.

2015-10-01

There exist many reviews on the biological and biochemical interactions of cancer cells and endothelial cells during the transmigration and tissue invasion of cancer cells. For the malignant progression of cancer, the ability to metastasize is a prerequisite. In particular, this means that certain cancer cells possess the property to migrate through the endothelial lining into blood or lymph vessels, and are possibly able to transmigrate through the endothelial lining into the connective tissue and follow up their invasion path in the targeted tissue. On the molecular and biochemical level the transmigration and invasion steps are well-defined, but these signal transduction pathways are not yet clear and less understood in regards to the biophysical aspects of these processes. To functionally characterize the malignant transformation of neoplasms and subsequently reveal the underlying pathway(s) and cellular properties, which help cancer cells to facilitate cancer progression, the biomechanical properties of cancer cells and their microenvironment come into focus in the physics-of-cancer driven view on the metastasis process of cancers. Hallmarks for cancer progression have been proposed, but they still lack the inclusion of specific biomechanical properties of cancer cells and interacting surrounding endothelial cells of blood or lymph vessels. As a cancer cell is embedded in a special environment, the mechanical properties of the extracellular matrix also cannot be neglected. Therefore, in this review it is proposed that a novel hallmark of cancer that is still elusive in classical tumor biological reviews should be included, dealing with the aspect of physics in cancer disease such as the natural selection of an aggressive (highly invasive) subtype of cancer cells displaying a certain adhesion or chemokine receptor on their cell surface. Today, the physical aspects can be analyzed by using state-of-the-art biophysical methods. Thus, this review will present current cancer research in a different light from a physical point of view with respect to cancer cell mechanics and the special and unique role of the endothelium on cancer cell invasion. The physical view on cancer disease may lead to novel insights into cancer disease and will help to overcome the classical views on cancer. In addition, in this review it will be discussed how physics of cancer can help to reveal and propose the functional mechanism which cancer cells use to invade connective tissue and transmigrate through the endothelium to finally metastasize. Finally, in this review it will be demonstrated how biophysical measurements can be combined with classical analysis approaches of tumor biology. The insights into physical interactions between cancer cells, the endothelium and the microenvironment may help to answer some "old," but still important questions in cancer disease progression.

Thermally Sprayed High Temperature Sandwich Structures: Physical Properties and Mechanical Performance

NASA Astrophysics Data System (ADS)

Salavati, Saeid

Metallic foam core sandwich structures have been of particular interest for engineering applications in recent decades due to their unique physical and mechanical properties. One of the potential applications of open pore metallic foam core sandwich structures is in heat exchangers. An investigation of sandwich structures fabricated from materials suitable for application at high temperatures and in corrosive environments was undertaken in this project. A novel method for fabrication of metallic foam core sandwich structures is thermal spray deposition of the faces on the prepared surfaces of the metallic foam substrate. The objective of the current study was to optimize the twin wire arc spray process parameters for the deposition of alloy 625 faces with controllable porosity content on the nickel foam substrate, and to characterize the physical and mechanical properties of the sandwich structure. The experimental investigations consisted of microstructural evaluation of the skin material and the foam substrate, investigation of the effect of alloying on the mechanical and thermal properties of the nickel foam, optimization of the grit-blasting and arc spray processes, observation of mechanical properties of the alloy 625 deposit by tensile testing and evaluation of the overall mechanical properties of the sandwich structure under flexural loading condition. The optimization of arc spraying process parameters allowed deposition of alloy 625 faces with a porosity of less than 4% for heat exchanger applications. Modification of the arc spraying process by co-deposition of polyester powder enabled 20% porosity to be obtained in the deposited faces for heat shield applications with film cooling. The effects of nickel foam alloying and heat treatment on the flexural rigidity of the sandwich structures were investigated and compared with as-received foam and as-fabricated sandwich structures. Available analytical models were employed to describe the effect of constituents' mechanical properties on the overall mechanical performance of the sandwich structures. Finite element modeling using ANSYS Structural was used to simulate the behaviour of the sandwich structures in four-point bending. The analytical and simulation results were compared with the experimental results obtained from the flexural tests.

Physics with e{sup +}e{sup -} Linear Colliders

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

Barklow, Timothy L

2003-05-05

We describe the physics potential of e{sup +}e{sup -} linear colliders in this report. These machines are planned to operate in the first phase at a center-of-mass energy of 500 GeV, before being scaled up to about 1 TeV. In the second phase of the operation, a final energy of about 2 TeV is expected. The machines will allow us to perform precision tests of the heavy particles in the Standard Model, the top quark and the electroweak bosons. They are ideal facilities for exploring the properties of Higgs particles, in particular in the intermediate mass range. New vector bosonsmore » and novel matter particles in extended gauge theories can be searched for and studied thoroughly. The machines provide unique opportunities for the discovery of particles in supersymmetric extensions of the Standard Model, the spectrum of Higgs particles, the supersymmetric partners of the electroweak gauge and Higgs bosons, and of the matter particles. High precision analyses of their properties and interactions will allow for extrapolations to energy scales close to the Planck scale where gravity becomes significant. In alternative scenarios, like compositeness models, novel matter particles and interactions can be discovered and investigated in the energy range above the existing colliders up to the TeV scale. Whatever scenario is realized in Nature, the discovery potential of e{sup +}e{sup -} linear colliders and the high-precision with which the properties of particles and their interactions can be analyzed, define an exciting physics programme complementary to hadron machines.« less

Nanoscale “fluorescent stone”: Luminescent Calcium Fluoride Nanoparticles as Theranostic Platforms

PubMed Central

Li, Zhanjun; Zhang, Yuanwei; Huang, Ling; Yang, Yuchen; Zhao, Yang; El-Banna, Ghida; Han, Gang

2016-01-01

Calcium Fluoride (CaF2) based luminescent nanoparticles exhibit unique, outstanding luminescent properties, and represent promising candidates as nanoplatforms for theranostic applications. There is an urgent need to facilitate their further development and applications in diagnostics and therapeutics as a novel class of nanotools. Here, in this critical review, we outlined the recent significant progresses made in CaF2-related nanoparticles: Firstly, their physical chemical properties, synthesis chemistry, and nanostructure fabrication are summarized. Secondly, their applications in deep tissue bio-detection, drug delivery, imaging, cell labeling, and therapy are reviewed. The exploration of CaF2-based luminescent nanoparticles as multifunctional nanoscale carriers for imaging-guided therapy is also presented. Finally, we discuss the challenges and opportunities in the development of such CaF2-based platform for future development in regard to its theranostic applications. PMID:27877242

All-solid-state flexible supercapacitors fabricated with bacterial nanocellulose papers, carbon nanotubes, and triblock-copolymer ion gels.

PubMed

Kang, Yu Jin; Chun, Sang-Jin; Lee, Sung-Suk; Kim, Bo-Yeong; Kim, Jung Hyeun; Chung, Haegeun; Lee, Sun-Young; Kim, Woong

2012-07-24

We demonstrate all-solid-state flexible supercapacitors with high physical flexibility, desirable electrochemical properties, and excellent mechanical integrity, which were realized by rationally exploiting unique properties of bacterial nanocellulose, carbon nanotubes, and ionic liquid based polymer gel electrolytes. This deliberate choice and design of main components led to excellent supercapacitor performance such as high tolerance against bending cycles and high capacitance retention over charge/discharge cycles. More specifically, the performance of our supercapacitors was highly retained through 200 bending cycles to a radius of 3 mm. In addition, the supercapacitors showed excellent cyclability with C(sp) (~20 mF/cm(2)) reduction of only <0.5% over 5000 charge/discharge cycles at the current density of 10 A/g. Our demonstration could be an important basis for material design and development of flexible supercapacitors.

Electric Switching of Fluorescence Decay in Gold-Silica-Dye Nematic Nanocolloids Mediated by Surface Plasmons.

PubMed

Jiang, Li; Mundoor, Haridas; Liu, Qingkun; Smalyukh, Ivan I

2016-07-26

Tunable composite materials with interesting physical behavior can be designed through integrating unique optical properties of solid nanostructures with facile responses of soft matter to weak external stimuli, but this approach remains challenged by their poorly controlled coassembly at the mesoscale. Using scalable wet chemical synthesis procedures, we fabricated anisotropic gold-silica-dye colloidal nanostructures and then organized them into the device-scale (demonstrated for square-inch cells) electrically tunable composites by simultaneously invoking molecular and colloidal self-assembly. We show that the ensuing ordered colloidal dispersions of shape-anisotropic nanostructures exhibit tunable fluorescence decay rates and intensity. We characterize how these properties depend on low-voltage fields and polarization of both the excitation and emission light, demonstrating a great potential for the practical realization of an interesting breed of nanostructured composite materials.

Application of ionic liquid in liquid phase microextraction technology.

PubMed

Han, Dandan; Tang, Baokun; Lee, Yu Ri; Row, Kyung Ho

2012-11-01

Ionic liquids (ILs) are novel nonmolecular solvents. Their unique properties, such as high thermal stability, tunable viscosity, negligible vapor pressure, nonflammability, and good solubility for inorganic and organic compounds, make them excellent candidates as extraction media for a range of microextraction techniques. Many physical properties of ILs can be varied, and the structural design can be tuned to impart the desired functionality and enhance the analyte extraction selectivity, efficiency, and sensitivity. This paper provides an overview of the applications of ILs in liquid phase microextraction technology, such as single-drop microextraction, hollow fiber based liquid phase microextraction, and dispersive liquid-liquid microextraction. The sensitivity, linear calibration range, and detection limits for a range of target analytes in the methods were analyzed to determine the advantages of ILs in liquid phase microextraction. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Freestanding palladium nanosheets with plasmonic and catalytic properties

NASA Astrophysics Data System (ADS)

Huang, Xiaoqing; Tang, Shaoheng; Mu, Xiaoliang; Dai, Yan; Chen, Guangxu; Zhou, Zhiyou; Ruan, Fangxiong; Yang, Zhilin; Zheng, Nanfeng

2011-01-01

Ultrathin metal films can exhibit quantum size and surface effects that give rise to unique physical and chemical properties. Metal films containing just a few layers of atoms can be fabricated on substrates using deposition techniques, but the production of freestanding ultrathin structures remains a significant challenge. Here we report the facile synthesis of freestanding hexagonal palladium nanosheets that are less than 10 atomic layers thick, using carbon monoxide as a surface confining agent. The as-prepared nanosheets are blue in colour and exhibit a well-defined but tunable surface plasmon resonance peak in the near-infrared region. The combination of photothermal stability and biocompatibility makes palladium nanosheets promising candidates for photothermal therapy. The nanosheets also exhibit electrocatalytic activity for the oxidation of formic acid that is 2.5 times greater than that of commercial palladium black catalyst.

Novel graphene-oxide-coated SPR interfaces for biosensing applications

NASA Astrophysics Data System (ADS)

Volkov, V. S.; Stebunov, Yu. V.; Yakubovsky, D. I.; Fedyanin, D. Yu.; Arsenin, A. V.

2017-09-01

Carbon allotropes-based nanomaterials possess unique physical and chemical properties including high surface area, the possibility of pi-stacking interaction with a wide range of biological objects, rich availability of oxygen-containing functional groups in graphene-oxide (GO), and excellent optical properties, which make them an ideal candidate for use as a universal immobilization platform in SPR biosensing. Here, we propose a new surface plasmon resonance (SPR) biosensing interface for sensitive and selective detection of small molecules. This interface is based on the GO linking layers deposited on the gold/copper surface of SPR sensor chips. To estimate the binding capacity of GO layers, modification of carboxyl groups to N-Hydroxysuccinimide esters was performed in the flow cell of SPR instrument. For comparison, the same procedure was applied to commercial sensor chips based on linking layers of carboxymethylated dextran.

Hydroxyapatite-TiO(2)-based nanocomposites synthesized in supercritical CO(2) for bone tissue engineering: physical and mechanical properties.

PubMed

Salarian, Mehrnaz; Xu, William Z; Wang, Zhiqiang; Sham, Tsun-Kong; Charpentier, Paul A

2014-10-08

Calcium phosphate-based nanocomposites offer a unique solution toward producing scaffolds for orthopedic and dental implants. However, despite attractive bioactivity and biocompatibility, hydroxyapatite (HAp) has been limited in heavy load-bearing applications due to its intrinsically low mechanical strength. In this work, to improve the mechanical properties of HAp, we grew HAp nanoplates from the surface of one-dimensional titania nanorod structures by combining a coprecipitation and sol-gel methodology using supercritical fluid processing with carbon dioxide (scCO2). The effects of metal alkoxide concentration (1.1-1.5 mol/L), reaction temperature (60-80 °C), and pressure (6000-8000 psi) on the morphology, crystallinity, and surface area of the resulting nanostructured composites were examined using scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (XRD), and Brunauer-Emmet-Teller (BET) method. Chemical composition of the products was characterized using Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and X-ray absorption near-edge structure (XANES) analyses. HAp nanoplates and HAp-TiO2 nanocomposites were homogeneously mixed within poly(ε-caprolactone) (PCL) to develop scaffolds with enhanced physical and mechanical properties for bone regeneration. Mechanical behavior analysis demonstrated that the Young's and flexural moduli of the PCL/HAp-TiO2 composites were substantially higher than the PCL/HAp composites. Therefore, this new synthesis methodology in scCO2 holds promise for bone tissue engineering with improved mechanical properties.

Weak unique continuation property and a related inverse source problem for time-fractional diffusion-advection equations

NASA Astrophysics Data System (ADS)

Jiang, Daijun; Li, Zhiyuan; Liu, Yikan; Yamamoto, Masahiro

2017-05-01

In this paper, we first establish a weak unique continuation property for time-fractional diffusion-advection equations. The proof is mainly based on the Laplace transform and the unique continuation properties for elliptic and parabolic equations. The result is weaker than its parabolic counterpart in the sense that we additionally impose the homogeneous boundary condition. As a direct application, we prove the uniqueness for an inverse problem on determining the spatial component in the source term by interior measurements. Numerically, we reformulate our inverse source problem as an optimization problem, and propose an iterative thresholding algorithm. Finally, several numerical experiments are presented to show the accuracy and efficiency of the algorithm.

Superconducting selenides intercalated with organic molecules: synthesis, crystal structure, electric and magnetic properties, superconducting properties, and phase separation in iron based-chalcogenides and hybrid organic-inorganic superconductors

NASA Astrophysics Data System (ADS)

Krzton-Maziopa, Anna; Pesko, Edyta; Puzniak, Roman

2018-06-01

Layered iron-based superconducting chalcogenides intercalated with molecular species are the subject of intensive studies, especially in the field of solid state chemistry and condensed matter physics, because of their intriguing chemistry and tunable electric and magnetic properties. Considerable progress in the research, revealing superconducting inorganic–organic hybrid materials with transition temperatures to superconducting state, T c, up to 46 K, has been brought in recent years. These novel materials are synthesized by low-temperature intercalation of molecular species, such as solvates of alkali metals and nitrogen-containing donor compounds, into layered FeSe-type structure. Both the chemical nature as well as orientation of organic molecules between the layers of inorganic host, play an important role in structural modifications and may be used for fine tuning of superconducting properties. Furthermore, a variety of donor species compatible with alkali metals, as well as the possibility of doping also in the host structure (either on Fe or Se sites), makes this system quite flexible and gives a vast array of new materials with tunable electric and magnetic properties. In this review, the main aspects of intercalation chemistry are discussed with a particular attention paid to the influence of the unique nature of intercalating species on the crystal structure and physical properties of the hybrid inorganic–organic materials. To get a full picture of these materials, a comprehensive description of the most effective chemical and electrochemical methods, utilized for synthesis of intercalated species, with critical evaluation of their strong and weak points, related to feasibility of synthesis, phase purity, crystal size and morphology of final products, is included as well.

Self-assembled phase-change nanowire for nonvolatile electronic memory

NASA Astrophysics Data System (ADS)

Jung, Yeonwoong

One of the most important subjects in nanosciences is to identify and exploit the relationship between size and structural/physical properties of materials and to explore novel material properties at a small-length scale. Scale-down of materials is not only advantageous in realizing miniaturized devices but nanometer-sized materials often exhibit intriguing physical/chemical properties that greatly differ from their bulk counterparts. This dissertation studies self-assembled phase-change nanowires for future nonvolatile electronic memories, mainly focusing on their size-dependent memory switching properties. Owing to the one-dimensional, unique geometry coupled with the small and tunable sizes, bottom-designed nanowires offer great opportunities in terms for both fundamental science and practical engineering perspectives, which would be difficult to realize in conventional top-down based approaches. We synthesized chalcogenide phase-change nanowires of different compositions and sizes, and studied their electronic memory switching owing to the structural change between crystalline and amorphous phases. In particular, we investigated nanowire size-dependent memory switching parameters, including writing current, power consumption, and data retention times, as well as studying composition-dependent electronic properties. The observed size and composition-dependent switching and recrystallization kinetics are explained based on the heat transport model and heterogeneous nucleation theories, which help to design phase-change materials with better properties. Moreover, we configured unconventional heterostructured phase-change nanowire memories and studied their multiple memory states in single nanowire devices. Finally, by combining in-situ/ex-situ electron microscopy techniques and electrical measurements, we characterized the structural states involved in electrically-driven phase-change in order to understand the atomistic mechanism that governs the electronic memory switching through phase-change.

Anisotropic nanomaterials: structure, growth, assembly, and functions

PubMed Central

Sajanlal, Panikkanvalappil R.; Sreeprasad, Theruvakkattil S.; Samal, Akshaya K.; Pradeep, Thalappil

2011-01-01

Comprehensive knowledge over the shape of nanomaterials is a critical factor in designing devices with desired functions. Due to this reason, systematic efforts have been made to synthesize materials of diverse shape in the nanoscale regime. Anisotropic nanomaterials are a class of materials in which their properties are direction-dependent and more than one structural parameter is needed to describe them. Their unique and fine-tuned physical and chemical properties make them ideal candidates for devising new applications. In addition, the assembly of ordered one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D) arrays of anisotropic nanoparticles brings novel properties into the resulting system, which would be entirely different from the properties of individual nanoparticles. This review presents an overview of current research in the area of anisotropic nanomaterials in general and noble metal nanoparticles in particular. We begin with an introduction to the advancements in this area followed by general aspects of the growth of anisotropic nanoparticles. Then we describe several important synthetic protocols for making anisotropic nanomaterials, followed by a summary of their assemblies, and conclude with major applications. PMID:22110867

Prospects for graphene–nanoparticle-based hybrid sensors

PubMed Central

Yin, Perry T.; Kim, Tae-Hyung; Choi, Jeong-Woo; Lee, Ki-Bum

2014-01-01

Graphene is a single-atom thick, two-dimensional sheet of carbon that is characterized by exceptional chemical, electrical, material, optical, and physical properties. As a result, graphene and related materials, such as graphene oxide and reduced graphene oxide, have been brought to the forefront in the field of sensing. Recently, a number of reports have demonstrated that graphene–nanoparticle hybrid structures can act synergistically to offer a number of unique physicochemical properties that are desirable and advantageous for sensing applications. These graphene–nanoparticle hybrid structures are particularly interesting because not only do they display the individual properties of the nanoparticles and of graphene, but they can also exhibit additional synergistic properties thereby enhancing the achievable sensitivity and selectivity using a variety of sensing mechanisms. As such, in this perspective, we will discuss the progress that has been made in the development and application of graphene–nanoparticle hybrid sensors and their future prospects. In particular, we will focus on the preparation of graphene–nanoparticle hybrid structures as well as their application in electronic, electrochemical, and optical sensors. PMID:23828095

Production of durable expanded perlite microspheres in a Vertical Electrical Furnace

NASA Astrophysics Data System (ADS)

Panagiotis, M.; Angelopoulos, P.; Taxiarchou, M.; Paspaliaris, I.

2016-04-01

Expanded perlite constitutes one of the most competitive insulating materials that is widely used in construction and manufacturing industry due to its unique properties combination; it is white, natural, lightweight, chemically inert, and exhibits superior insulating properties (thermal and acoustic) and fire resistance. Conventionally, perlite expansion is performed in vertical gas-fired furnaces; the conventional perlite expansion process has certain disadvantages which affect expanded products quality, thus limiting their performance and range of applications. In order to overcome the drawbacks of the conventional expansion technique, a new perlite expansion process has been designed based on a vertical electrical furnace (VEF). In the current study, fine perlite samples (-150 μm) from Milos Island, Greece, were expansed in the novel VEF and a conventional gas-fired furnace with the aim to evaluate and compare the main physical properties of the expanded products. The novel expanded perlite particles were characterised by superior properties, namely increased compression strength, competitive water and oil absorption capability, size homogeneity, spherical shape and decreased surface porosity in comparison to conventionally expanded samples.

Enhancement of conductance of GaAs sub-microwires under external stimuli

NASA Astrophysics Data System (ADS)

Qu, Xianlin; Deng, Qingsong; Zheng, Kun

2018-03-01

Semiconductors with one dimension on the micro-nanometer scale have many unique physical properties that are remarkably different from those of their bulk counterparts. Moreover, changes in the external field will further modulate the properties of the semiconductor micro-nanomaterials. In this study, we used focused ion beam technology to prepare freestanding ⟨111⟩-oriented GaAs sub-microwires from a GaAs substrate. The effects of laser irradiation and bending or buckling deformation induced by compression on the electrical transport properties of an individual GaAs sub-microwire were studied. The experimental results indicate that both laser irradiation and bending deformation can enhance their electrical transport properties, the laser irradiation resulted in a conductance enhancement of ˜30% compared to the result with no irradiation, and in addition, bending deformation changed the conductance by as much as ˜180% when the average strain was approximately 1%. The corresponding mechanisms are also discussed. This study provides beneficial insight into the fabrication of electronic and optoelectronic devices based on GaAs micro/nano-wires.

Iridescence: a functional perspective

PubMed Central

Doucet, Stéphanie M.; Meadows, Melissa G.

2009-01-01

In animals, iridescence is generated by the interaction of light with biological tissues that are nanostructured to produce thin films or diffraction gratings. Uniquely among animal visual signals, the study of iridescent coloration contributes to biological and physical sciences by enhancing our understanding of the evolution of communication strategies, and by providing insights into physical optics and inspiring biomimetic technologies useful to humans. Iridescent colours are found in a broad diversity of animal taxa ranging from diminutive marine copepods to terrestrial insects and birds. Iridescent coloration has received a surge of research interest of late, and studies have focused on both characterizing the nanostructures responsible for producing iridescence and identifying the behavioural functions of iridescent colours. In this paper, we begin with a brief description of colour production mechanisms in animals and provide a general overview of the taxonomic distribution of iridescent colours. We then highlight unique properties of iridescent signals and review the proposed functions of iridescent coloration, focusing, in particular, on the ways in which iridescent colours allow animals to communicate with conspecifics and avoid predators. We conclude with a brief overview of non-communicative functions of iridescence in animals. Despite the vast amount of recent work on animal iridescence, our review reveals that many proposed functions of iridescent coloration remain virtually unexplored, and this area is clearly ripe for future research. PMID:19336344

A Review of Selected Studies That Determine the Physical and Chemical Properties of Saliva in the Field of Dental Treatment

PubMed Central

Kubala, Elżbieta; Strzelecka, Paulina; Grzegocka, Marta; Lietz-Kijak, Danuta; Gronwald, Helena; Skomro, Piotr

2018-01-01

Physiological whole saliva is a unique body fluid constantly washing the mucous membranes of the mouth, throat, and larynx. Saliva is a clear, slightly acidic mucinous-serous secretion, composed of various electrolytes, small organic substances, proteins, peptides, and polynucleotides. There are many ways to use saliva as a biological fluid (biofluid). The significant advantages of saliva as a unique diagnostic material are its availability and the noninvasive method of collection. The aim of this review is to emphasize the diagnostic value of saliva as a research material in the configuration of its structure and secretion disorders. The data were obtained using the MEDLINE (PubMed) search engine, as well as an additional manual search. The analysis covered 77 articles selected from a group of 1986 publications and initially qualified for devising. The results were evaluated and checked for the correctness of qualifying in accordance with inclusion and exclusion criteria. The diagnostic use of saliva has attracted the attention of many researchers due to its noninvasive nature and relative simplicity of collection. In addition, it should be noted that the determination of chemical and physical saliva parameters can be effectively performed in the patient's presence in the dental office. PMID:29854777

Evaluation of the automatic optical authentication technologies for control systems of objects

NASA Astrophysics Data System (ADS)

Averkin, Vladimir V.; Volegov, Peter L.; Podgornov, Vladimir A.

2000-03-01

The report considers the evaluation of the automatic optical authentication technologies for the automated integrated system of physical protection, control and accounting of nuclear materials at RFNC-VNIITF, and for providing of the nuclear materials nonproliferation regime. The report presents the nuclear object authentication objectives and strategies, the methodology of the automatic optical authentication and results of the development of pattern recognition techniques carried out under the ISTC project #772 with the purpose of identification of unique features of surface structure of a controlled object and effects of its random treatment. The current decision of following functional control tasks is described in the report: confirmation of the item authenticity (proof of the absence of its substitution by an item of similar shape), control over unforeseen change of item state, control over unauthorized access to the item. The most important distinctive feature of all techniques is not comprehensive description of some properties of controlled item, but unique identification of item using minimum necessary set of parameters, properly comprising identification attribute of the item. The main emphasis in the technical approach is made on the development of rather simple technological methods for the first time intended for use in the systems of physical protection, control and accounting of nuclear materials. The developed authentication devices and system are described.

Comprehensive Understanding for Vegetated Scene Radiance Relationships

NASA Technical Reports Server (NTRS)

Kimes, D. S.; Deering, D. W.

1984-01-01

The improvement of our fundamental understanding of the dynamics of directional scattering properties of vegetation canopies through analysis of field data and model simulation data is discussed. Directional reflectance distributions spanning the entire existance hemisphere were measured in two field studies; one using a Mark III 3-band radiometer and one using rapid scanning bidirectional field instrument called PARABOLA. Surfaces measured included corn, soybeans, bare soils, grass lawn, orchard grass, alfalfa, cotton row crops, plowed field, annual grassland, stipa grass, hard wheat, salt plain shrubland, and irrigated wheat. Some structural and optical measurements were taken. Field data show unique reflectance distributions ranging from bare soil to complete vegetation canopies. Physical mechanisms causing these trends are proposed based on scattering properties of soil and vegetation. Soil exhibited a strong backscattering peak toward the Sun. Complete vegetation exhibited a bowl distribution with the minimum reflectance near nadir. Incomplete vegetation canopies show shifting of the minimum reflectance off of nadir in the forward scattering direction because both the scattering properties or the vegetation and soil are observed.

Stimulus-responsive hydrogels: Theory, modern advances, and applications

PubMed Central

Koetting, Michael C.; Peters, Jonathan T.; Steichen, Stephanie D.; Peppas, Nicholas A.

2016-01-01

Over the past century, hydrogels have emerged as effective materials for an immense variety of applications. The unique network structure of hydrogels enables very high levels of hydrophilicity and biocompatibility, while at the same time exhibiting the soft physical properties associated with living tissue, making them ideal biomaterials. Stimulus-responsive hydrogels have been especially impactful, allowing for unprecedented levels of control over material properties in response to external cues. This enhanced control has enabled groundbreaking advances in healthcare, allowing for more effective treatment of a vast array of diseases and improved approaches for tissue engineering and wound healing. In this extensive review, we identify and discuss the multitude of response modalities that have been developed, including temperature, pH, chemical, light, electro, and shear-sensitive hydrogels. We discuss the theoretical analysis of hydrogel properties and the mechanisms used to create these responses, highlighting both the pioneering and most recent work in all of these fields. Finally, we review the many current and proposed applications of these hydrogels in medicine and industry. PMID:27134415

The influence of α-Al2O3 addition on microstructure, mechanical and formaldehyde adsorption properties of fly ash-based geopolymer products.

PubMed

Huang, Yi; Han, Minfang

2011-10-15

Fly ash-based geopolymer with α-Al(2)O(3) addition were synthesized and used to remove formaldehyde from indoor air. The microstructure, mechanical and formaldehyde adsorption properties of the geopolymer products obtained were investigated. The results showed that α-Al(2)O(3) addition with appropriate amount (such as 5 wt%) increased the geopolymerization extent, resulting in the increase of surface area and compressive strength. In addition, the improvement of structural ordering level for geopolymer sample with 5 wt% α-Al(2)O(3) addition was found through FTIR analysis. By contrast, excessive addition (such as 10 wt%) had the opposite effect. The test of formaldehyde adsorption capacity confirmed that fly ash-based geopolymer product exhibited much better property of adsorbing indoor formaldehyde physically and chemically than fly ash itself. The surface area was an important but not unique factor influencing the adsorption capacity of geopolymers. Copyright © 2011 Elsevier B.V. All rights reserved.

High-performance a MoS2 nanosheet-based nonvolatile memory transistor with a ferroelectric polymer and graphene source-drain electrode

NASA Astrophysics Data System (ADS)

Lee, Young Tack; Hwang, Do Kyung; Im, Seongil

2015-11-01

Two-dimensional (2D) van der Waals (vdWs) materials are a class of new materials due to their unique physical properties. Of the many 2D vdWs materials, molybdenum disulfide (MoS2) is a representative n-type transition-metal dichalcogenide (TMD) semiconductor. Here, we report on a high-performance MoS2 nanosheet-based nonvolatile memory transistor with a poly(vinylidenefluoride-trifluoroethylene) (P(VDF-TrFE)) ferroelectric top gate insulator. In order to enhance the ohmic contact property, we use graphene flakes as source/drain electrodes prepared by using the direct imprinting method with an elastomer stamp. The MoS2 ferroelectric field-effect transistor (FeFET) shows the highest linear electron mobility value of 175 cm2/Vs with a high on/off current ratio of more than 107, and a very clear memory window of more than 15 V. The program and erase dynamics and the static retention properties are also well demonstrated.

Critical V2O5/TeO2 Ratio Inducing Abrupt Property Changes in Vanadium Tellurite Glasses.

PubMed

Kjeldsen, Jonas; Rodrigues, Ana C M; Mossin, Susanne; Yue, Yuanzheng

2014-12-26

Transition metal containing glasses have unique electrical properties and are therefore often used for electrochemical applications, such as in batteries. Among oxide glasses, vanadium tellurite glasses exhibit the highest electronic conductivity and thus the high potential for applications. In this work, we investigate how the dynamic and physical properties vary with composition in the vanadium tellurite system. The results show that there exists a critical V(2)O(5) concentration of 45 mol %, above which the local structure is subjected to a drastic change with increasing V(2)O(5), leading to abrupt changes in both hardness and liquid fragility. Electronic conductivity does not follow the expected correlation to the valence state of the vanadium as predicted by the Mott-Austin equation but shows a linear correlation to the mean distance between vanadium ions. These findings could contribute to designing optimum vanadium tellurite compositions for electrochemical devices. The work gives insight into the mechanism of electron conduction in the vanadium tellurite systems.

Topological insulator bismuth selenide as a theranostic platform for simultaneous cancer imaging and therapy.

PubMed

Li, Juan; Jiang, Fei; Yang, Bo; Song, Xiao-Rong; Liu, Yan; Yang, Huang-Hao; Cao, Dai-Rong; Shi, Wen-Rong; Chen, Guo-Nan

2013-01-01

Employing theranostic nanoparticles, which combine both therapeutic and diagnostic capabilities in one dose, has promise to propel the biomedical field toward personalized medicine. Here we investigate the theranostic properties of topological insulator bismuth selenide (Bi2Se3) in in vivo and in vitro system for the first time. We show that Bi2Se3 nanoplates can absorb near-infrared (NIR) laser light and effectively convert laser energy into heat. Such photothermal conversion property may be due to the unique physical properties of topological insulators. Furthermore, localized and irreversible photothermal ablation of tumors in the mouse model is successfully achieved by using Bi2Se3 nanoplates and NIR laser irradiation. In addition, we also demonstrate that Bi2Se3 nanoplates exhibit strong X-ray attenuation and can be utilized for enhanced X-ray computed tomography imaging of tumor tissue in vivo. This study highlights Bi2Se3 nanoplates could serve as a promising platform for cancer diagnosis and therapy.

Peripheral mechanisms for vocal production in birds - differences and similarities to human speech and singing.

PubMed

Riede, Tobias; Goller, Franz

2010-10-01

Song production in songbirds is a model system for studying learned vocal behavior. As in humans, bird phonation involves three main motor systems (respiration, vocal organ and vocal tract). The avian respiratory mechanism uses pressure regulation in air sacs to ventilate a rigid lung. In songbirds sound is generated with two independently controlled sound sources, which reside in a uniquely avian vocal organ, the syrinx. However, the physical sound generation mechanism in the syrinx shows strong analogies to that in the human larynx, such that both can be characterized as myoelastic-aerodynamic sound sources. Similarities include active adduction and abduction, oscillating tissue masses which modulate flow rate through the organ and a layered structure of the oscillating tissue masses giving rise to complex viscoelastic properties. Differences in the functional morphology of the sound producing system between birds and humans require specific motor control patterns. The songbird vocal apparatus is adapted for high speed, suggesting that temporal patterns and fast modulation of sound features are important in acoustic communication. Rapid respiratory patterns determine the coarse temporal structure of song and maintain gas exchange even during very long songs. The respiratory system also contributes to the fine control of airflow. Muscular control of the vocal organ regulates airflow and acoustic features. The upper vocal tract of birds filters the sounds generated in the syrinx, and filter properties are actively adjusted. Nonlinear source-filter interactions may also play a role. The unique morphology and biomechanical system for sound production in birds presents an interesting model for exploring parallels in control mechanisms that give rise to highly convergent physical patterns of sound generation. More comparative work should provide a rich source for our understanding of the evolution of complex sound producing systems. Copyright © 2009 Elsevier Inc. All rights reserved.

An introductory study using impedance spectroscopy technique with polarizable microelectrode for amino acids characterization

NASA Astrophysics Data System (ADS)

Chin, K. B.; Chi, I.; Pasalic, J.; Huang, C.-K.; Barge, Laura M.

2018-04-01

Portable, low power, yet ultra-sensitive life detection instrumentations are vital to future astrobiology flight programs at NASA. In this study, initial attempts to characterize amino acids in an aqueous environment by electrochemical impedance spectroscopy (EIS) using polarizable (blocking) electrodes in order to establish a means of detection via their electrical properties. Seven amino acids were chosen due to their scientific importance in demonstrating sensitivity levels in the range of part per billion concentration. Albeit more challenging in real systems of analyst mixtures, we found individual amino acids in aqueous environment do exhibit some degree of chemical and physical uniqueness to warrant characterization by EIS. The polar amino acids (Asp, Glu, and His) exhibited higher electrochemical activity than the non-polar amino acids (Ala, Gly, Val, and Leu). The non-polar amino acids (Gly and Ala) also exhibited unique electrical properties which appeared to be more dependent on physical characteristics such as molecular weight and structure. At concentrations above 1 mM where the amino acids play a more dominant transport role within the water, the conductivity was found to be more sensitive to concentrations. At lower concentrations <1 mM, however, the polar amino acid solution conductivity remained constant, suggesting poor chemical activity with water. As revealed by equivalent circuit modeling, the relaxation times showed a 1-2 order of magnitude difference between polar and non-polar amino acids. The pseudo-capacitance from EIS measurements on sample mixtures containing salt water and individual amino acids revealed the possibility for improvement in amino acid selectivity using gold nanoporous surface enhanced electrodes. This work establishes important methodologies for characterizing amino acids using EIS combined with microscale electrodes, supporting the case for instrumentation development for life detection and origin of life programs.

An introductory study using impedance spectroscopy technique with polarizable microelectrode for amino acids characterization.

PubMed

Chin, K B; Chi, I; Pasalic, J; Huang, C-K; Barge, Laura M

2018-04-01

Portable, low power, yet ultra-sensitive life detection instrumentations are vital to future astrobiology flight programs at NASA. In this study, initial attempts to characterize amino acids in an aqueous environment by electrochemical impedance spectroscopy (EIS) using polarizable (blocking) electrodes in order to establish a means of detection via their electrical properties. Seven amino acids were chosen due to their scientific importance in demonstrating sensitivity levels in the range of part per billion concentration. Albeit more challenging in real systems of analyst mixtures, we found individual amino acids in aqueous environment do exhibit some degree of chemical and physical uniqueness to warrant characterization by EIS. The polar amino acids (Asp, Glu, and His) exhibited higher electrochemical activity than the non-polar amino acids (Ala, Gly, Val, and Leu). The non-polar amino acids (Gly and Ala) also exhibited unique electrical properties which appeared to be more dependent on physical characteristics such as molecular weight and structure. At concentrations above 1 mM where the amino acids play a more dominant transport role within the water, the conductivity was found to be more sensitive to concentrations. At lower concentrations <1 mM, however, the polar amino acid solution conductivity remained constant, suggesting poor chemical activity with water. As revealed by equivalent circuit modeling, the relaxation times showed a 1-2 order of magnitude difference between polar and non-polar amino acids. The pseudo-capacitance from EIS measurements on sample mixtures containing salt water and individual amino acids revealed the possibility for improvement in amino acid selectivity using gold nanoporous surface enhanced electrodes. This work establishes important methodologies for characterizing amino acids using EIS combined with microscale electrodes, supporting the case for instrumentation development for life detection and origin of life programs.

One-pot synthesis of biocompatible Te@phenol formaldehyde resin core-shell nanowires with uniform size and unique fluorescent properties by a synergized soft-hard template process.

PubMed

Qian, Haisheng; Zhu, Enbo; Zheng, Shunji; Li, Zhengquan; Hu, Yong; Guo, Changfa; Yang, Xingyun; Li, Liangchao; Tong, Guoxiu; Guo, Huichen

2010-12-10

One-pot hydrothermal process has been developed to synthesize uniform Te@phenol formaldehyde resin core-shell nanowires with unique fluorescent properties. A synergistic soft-hard template mechanism has been proposed to explain the formation of the core-shell nanowires. The Te@phenol formaldehyde resin core-shell nanowires display unique fluorescent properties, which give strong luminescent emission in the blue-violet and green regions with excitation wavelengths of 270 nm and 402 nm, respectively.

Role of the CMS electromagnetic calorimeter in the measurement of the Higgs boson properties and search for new physics

NASA Astrophysics Data System (ADS)

Ferri, F.; CMS Collaboration

2016-04-01

The precise determination of the mass, the width and the couplings of the particle discovered in 2012 with a mass around 125 GeV is of capital importance to clarify the nature of such a particle, in particular to establish precisely if it is a Standard Model Higgs boson. In several new physics scenarios, in fact, the Higgs boson may behave differently with respect to the Standard Model one, or may not be unique, i.e. there can be more than one Higgs boson. In order to achieve the precision needed to discriminate between different models, the energy resolution, the scale uncertainty and the position resolution for electrons and photons are required to be as good as possible. The CMS scintillating lead-tungstate electromagnetic calorimeter (ECAL) was built as a precise tool with an exceptional energy resolution and a very good position resolution that improved over the years with the knowledge of the detector. Moreover, thanks to the fact that most of the lead-tungstate scintillation light is emitted in about 25 ns, the ECAL can be used to accurately determine the time of flight of photons. We present the current performance of the CMS ECAL, with a special emphasis on the impact on the measurement of the properties of the Higgs boson and on searches for new physics.

The mechanical microenvironment in cancer: How physics affects tumours.

PubMed

Nagelkerke, Anika; Bussink, Johan; Rowan, Alan E; Span, Paul N

2015-12-01

The tumour microenvironment contributes greatly to the response of tumour cells. It consists of chemical gradients, for example of oxygen and nutrients. However, a physical environment is also present. Apart from chemical input, cells also receive physical signals. Tumours display unique mechanical properties: they are a lot stiffer than normal tissue. This may be either a cause or a consequence of cancer, but literature suggests it has a major impact on tumour cells as will be described in this review. The mechanical microenvironment may cause malignant transformation, possibly through activation of oncogenic pathways and inhibition of tumour suppressor genes. In addition, the mechanical microenvironment may promote tumour progression by influencing processes such as epithelial-to-mesenchymal transition, enhancing cell survival through autophagy, but also affects sensitivity of tumour cells to therapeutics. Furthermore, multiple intracellular signalling pathways prove sensitive to the mechanical properties of the microenvironment. It appears the increased stiffness is unlikely to be caused by increased stiffness of the tumour cells themselves. However, there are indications that tumours display a higher cell density, making them more rigid. In addition, increased matrix deposition in the tumour, as well as increased interstitial fluid pressure may account for the increased stiffness of tumours. Overall, tumour mechanics are significantly different from normal tissue. Therefore, this feature should be further explored for use in cancer prevention, detection and treatment. Copyright © 2015 Elsevier Ltd. All rights reserved.

Narayanaswamy’s 1971 aging theory and material time

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

Dyre, Jeppe C., E-mail: dyre@ruc.dk

2015-09-21

The Bochkov-Kuzovlev nonlinear fluctuation-dissipation theorem is used to derive Narayanaswamy’s phenomenological theory of physical aging, in which this highly nonlinear phenomenon is described by a linear material-time convolution integral. A characteristic property of the Narayanaswamy aging description is material-time translational invariance, which is here taken as the basic assumption of the derivation. It is shown that only one possible definition of the material time obeys this invariance, namely, the square of the distance travelled from a configuration of the system far back in time. The paper concludes with suggestions for computer simulations that test for consequences of material-time translational invariance.more » One of these is the “unique-triangles property” according to which any three points on the system’s path form a triangle such that two side lengths determine the third; this is equivalent to the well-known triangular relation for time-autocorrelation functions of aging spin glasses [L. F. Cugliandolo and J. Kurchan, J. Phys. A: Math. Gen. 27, 5749 (1994)]. The unique-triangles property implies a simple geometric interpretation of out-of-equilibrium time-autocorrelation functions, which extends to aging a previously proposed framework for such functions in equilibrium [J. C. Dyre, e-print arXiv:cond-mat/9712222 (1997)].« less

Controlled Thermoresponsive Hydrogels by Stereocomplexed PLA-PEG-PLA Prepared via Hybrid Micelles of Pre-Mixed Copolymers with Different PEG Lengths

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

Abebe, Daniel G.; Fujiwara, Tomoko

2012-09-05

The stereocomplexed hydrogels derived from the micelle mixture of two enantiomeric triblock copolymers, PLLA-PEG-PLLA and PDLA-PEG-PDLA, reported in 2001 exhibited sol-to-gel transition at approximately body temperature upon heating. However, the showed poor storage modulus (ca. 1000 Pa) determined their insufficiency as injectable implant biomaterials for many applications. In this study, the mechanical property of these hydrogels was significantly improved by the modifications of molecular weights and micelle structure. Co-micelles composed of block copolymers with two sizes of PEG block length were shown to possess unique and dissimilar properties from the micelles composed of single-sized block copolymers. The stereomixture of PLA-PEG-PLAmore » comicelles showed a controllable sol-to-gel transition at a wide temperature range of 4 and 80 C. The sol-gel phase diagram displays a linear relationship of temperature versus copolymer composition; hence, a transition at body temperature can be readily achieved by adjusting the mixed copolymer ratio. The resulting thermoresponsive hydrogels exhibit a storage modulus notably higher (ca. 6000 Pa) than that of previously reported hydrogels. As a physical network solely governed by self-reorganization of micelles, followed by stereocomplexation, this unique system offers practical, safe, and simple implantable biomaterials.« less

Ionic Liquids in Selective Oxidation: Catalysts and Solvents.

PubMed

Dai, Chengna; Zhang, Jie; Huang, Chongpin; Lei, Zhigang

2017-05-24

Selective oxidation has an important role in environmental and green chemistry (e.g., oxidative desulfurization of fuels and oxidative removal of mercury) as well as chemicals and intermediates chemistry to obtain high-value-added special products (e.g., organic sulfoxides and sulfones, aldehydes, ketones, carboxylic acids, epoxides, esters, and lactones). Due to their unique physical properties such as the nonvolatility, thermal stability, nonexplosion, high polarity, and temperature-dependent miscibility with water, ionic liquids (ILs) have attracted considerable attention as reaction solvents and media for selective oxidations and are considered as green alternatives to volatile organic solvents. Moreover, for easy separation and recyclable utilization, IL catalysts have attracted unprecedented attention as "biphasic catalyst" or "immobilized catalyst" by immobilizing metal- or nonmetal-containing ILs onto mineral or polymer supports to combine the unique properties of ILs (chemical and thermal stability, capacity for extraction of polar substrates and reaction products) with the extended surface of the supports. This review highlights the most recent outcomes on ILs in several important typical oxidation reactions. The contents are arranged in the series of oxidation of sulfides, oxidation of alcohols, epoxidation of alkenes, Baeyer-Villiger oxidation reaction, oxidation of alkanes, and oxidation of other compounds step by step involving ILs as solvents, catalysts, reagents, or their combinations.

Emergence of charge density waves and a pseudogap in single-layer TiTe2.

PubMed

Chen, P; Pai, Woei Wu; Chan, Y-H; Takayama, A; Xu, C-Z; Karn, A; Hasegawa, S; Chou, M Y; Mo, S-K; Fedorov, A-V; Chiang, T-C

2017-09-11

Two-dimensional materials constitute a promising platform for developing nanoscale devices and systems. Their physical properties can be very different from those of the corresponding three-dimensional materials because of extreme quantum confinement and dimensional reduction. Here we report a study of TiTe 2 from the single-layer to the bulk limit. Using angle-resolved photoemission spectroscopy and scanning tunneling microscopy and spectroscopy, we observed the emergence of a (2 × 2) charge density wave order in single-layer TiTe 2 with a transition temperature of 92 ± 3 K. Also observed was a pseudogap of about 28 meV at the Fermi level at 4.2 K. Surprisingly, no charge density wave transitions were observed in two-layer and multi-layer TiTe 2 , despite the quasi-two-dimensional nature of the material in the bulk. The unique charge density wave phenomenon in the single layer raises intriguing questions that challenge the prevailing thinking about the mechanisms of charge density wave formation.Due to reduced dimensionality, the properties of 2D materials are often different from their 3D counterparts. Here, the authors identify the emergence of a unique charge density wave (CDW) order in monolayer TiTe 2 that challenges the current understanding of CDW formation.

Local numerical modelling of ultrasonic guided waves in linear and nonlinear media

NASA Astrophysics Data System (ADS)

Packo, Pawel; Radecki, Rafal; Kijanka, Piotr; Staszewski, Wieslaw J.; Uhl, Tadeusz; Leamy, Michael J.

2017-04-01

Nonlinear ultrasonic techniques provide improved damage sensitivity compared to linear approaches. The combination of attractive properties of guided waves, such as Lamb waves, with unique features of higher harmonic generation provides great potential for characterization of incipient damage, particularly in plate-like structures. Nonlinear ultrasonic structural health monitoring techniques use interrogation signals at frequencies other than the excitation frequency to detect changes in structural integrity. Signal processing techniques used in non-destructive evaluation are frequently supported by modeling and numerical simulations in order to facilitate problem solution. This paper discusses known and newly-developed local computational strategies for simulating elastic waves, and attempts characterization of their numerical properties in the context of linear and nonlinear media. A hybrid numerical approach combining advantages of the Local Interaction Simulation Approach (LISA) and Cellular Automata for Elastodynamics (CAFE) is proposed for unique treatment of arbitrary strain-stress relations. The iteration equations of the method are derived directly from physical principles employing stress and displacement continuity, leading to an accurate description of the propagation in arbitrarily complex media. Numerical analysis of guided wave propagation, based on the newly developed hybrid approach, is presented and discussed in the paper for linear and nonlinear media. Comparisons to Finite Elements (FE) are also discussed.

Functionalised carbon nanotubes: From intracellular uptake and cell-related toxicity to systemic brain delivery.

PubMed

Costa, Pedro M; Bourgognon, Maxime; Wang, Julie T-W; Al-Jamal, Khuloud T

2016-11-10

Carbon nanotubes (CNTs) have long been regarded as promising carriers in biomedicine. Due to their high surface area and unique needle-like structure, CNTs are uniquely equipped to carry therapeutic molecules across biological membranes and, therefore, have been widely researched for use in theranostic applications. The attractive properties of the CNTs entice also their use in the brain environment. Cutting edge brain-specific therapies, capable of circumventing the physical and biochemical blockage of the blood-brain barrier, could be a precious tool to tackle brain disorders. With an increasing number of applications and expanding production, the effects of direct and indirect exposure to CNTs on cellular and molecular levels and more globally the general health, must be carefully assessed and limited. In this chapter, we review the most recent trends on the development and application of CNT-based nanotechnologies, with a particular focus on the carrier properties, cell internalisation and processing, and mechanisms involved in cell toxicity. Novel approaches for CNT-based systemic therapeutic brain delivery following intravenous administration are also reviewed. Moreover, we highlight fundamental questions that should be addressed in future research involving CNTs, aiming at achieving its safe introduction into the clinics. Copyright © 2016 Elsevier B.V. All rights reserved.

An Extinction Probe Through the HD 107146 Debris Ring: Taking Unique Advantage of a Background Galaxy Transit

NASA Astrophysics Data System (ADS)

Schneider, Glenn

2016-10-01

We propose a 3-cycle GO program utilizing a total of HST 30 orbits to directly measure and map the line-of-sight optical depth through the brightest sector of the HD 107146 solar-analog debris ring by ring-transit differential photometry of a bright (compared to the disk), spatially extended, background galaxy. We will advantageously exploit its serendipitously unique and experiment-enabling high proper motion reflex trajectory w.r.t. the galaxy back-lighting a sectional slice the exoplanetary debris system (EDS) with a 2D grid of multiple sight-lines through the nearly face-on disk over time. These measures (the only opportunity for such in remaining HST lifetime) will uniquely provide unambiguous extinction/optical depth constraints to better elucidate the physical properties of the debris particles in this otherwise well studied EDS. With these and prior data we will: (a) disambiguate inferred particle spatial, size, and mass density distributions otherwise conflated with debris material optical property dependencies, (b) better constrain the posited pathways for planetary debris dust production mechanisms in EDSs (e.g., catastrophic collisions of parent bodies, dust-production cascades, cratering events, etc.) and (c) search for and discriminated between clumps , bumps , and clouds of collisional debris of varying particle (and mass) densities. This investigation was enabled in forethought by mapping the galaxy surface brightness out-of-transit in a comprehensive 2011 precursor study (HST GO/12228) using exactly the same STIS instrumental configuration with multi-roll PSF template subtracted coronagraphy we propose for the upcoming ring transit opportunity.

An Extinction Probe Through the HD 107146 Debris Ring: Taking Unique Advantage of a Background Galaxy Transit

NASA Astrophysics Data System (ADS)

Schneider, Glenn

2017-08-01

We propose a 3-cycle GO program utilizing a total of HST 30 orbits to directly measure and map the line-of-sight optical depth through the brightest sector of the HD 107146 solar-analog debris ring by ring-transit differential photometry of a bright (compared to the disk), spatially extended, background galaxy. We will advantageously exploit its serendipitously unique and experiment-enabling high proper motion reflex trajectory w.r.t. the galaxy back-lighting a sectional slice the exoplanetary debris system (EDS) with a 2D grid of multiple sight-lines through the nearly face-on disk over time. These measures (the only opportunity for such in remaining HST lifetime) will uniquely provide unambiguous extinction/optical depth constraints to better elucidate the physical properties of the debris particles in this otherwise well studied EDS. With these and prior data we will: (a) disambiguate inferred particle spatial, size, and mass density distributions otherwise conflated with debris material optical property dependencies, (b) better constrain the posited pathways for planetary debris dust production mechanisms in EDSs (e.g., catastrophic collisions of parent bodies, dust-production cascades, cratering events, etc.) and (c) search for and discriminated between clumps , bumps , and clouds of collisional debris of varying particle (and mass) densities. This investigation was enabled in forethought by mapping the galaxy surface brightness out-of-transit in a comprehensive 2011 precursor study (HST GO/12228) using exactly the same STIS instrumental configuration with multi-roll PSF template subtracted coronagraphy we propose for the upcoming ring transit opportunity.

Nanoparticle-Mediated Physical Exfoliation of Aqueous-Phase Graphene for Fabrication of Three-Dimensionally Structured Hybrid Electrodes.

PubMed

Lee, Younghee; Choi, Hojin; Kim, Min-Sik; Noh, Seonmyeong; Ahn, Ki-Jin; Im, Kyungun; Kwon, Oh Seok; Yoon, Hyeonseok

2016-01-27

Monodispersed polypyrrole (PPy) nanospheres were physically incorporated as guest species into stacked graphene layers without significant property degradation, thereby facilitating the formation of unique three-dimensional hybrid nanoarchitecture. The electrochemical properties of the graphene/particulate PPy (GPPy) nanohybrids were dependent on the sizes and contents of the PPy nanospheres. The nanohybrids exhibited optimum electrochemical performance in terms of redox activity, charge-transfer resistance, and specific capacitance at an 8:1 PPy/graphite (graphene precursor) weight ratio. The packing density of the alternately stacked nanohybrid structure varied with the nanosphere content, indicating the potential for high volumetric capacitance. The nanohybrids also exhibited good long-term cycling stability because of a structural synergy effect. Finally, fabricated nanohybrid-based flexible all-solid state capacitor cells exhibited good electrochemical performance in an acidic electrolyte with a maximum energy density of 8.4 Wh kg(-1) or 1.9 Wh L(-1) at a maximum power density of 3.2 kW kg(-1) or 0.7 kW L(-1); these performances were based on the mass or packing density of the electrode materials.

Self-healing and thermoreversible rubber from supramolecular assembly.

PubMed

Cordier, Philippe; Tournilhac, François; Soulié-Ziakovic, Corinne; Leibler, Ludwik

2008-02-21

Rubbers exhibit enormous extensibility up to several hundred per cent, compared with a few per cent for ordinary solids, and have the ability to recover their original shape and dimensions on release of stress. Rubber elasticity is a property of macromolecules that are either covalently cross-linked or connected in a network by physical associations such as small glassy or crystalline domains, ionic aggregates or multiple hydrogen bonds. Covalent cross-links or strong physical associations prevent flow and creep. Here we design and synthesize molecules that associate together to form both chains and cross-links via hydrogen bonds. The system shows recoverable extensibility up to several hundred per cent and little creep under load. In striking contrast to conventional cross-linked or thermoreversible rubbers made of macromolecules, these systems, when broken or cut, can be simply repaired by bringing together fractured surfaces to self-heal at room temperature. Repaired samples recuperate their enormous extensibility. The process of breaking and healing can be repeated many times. These materials can be easily processed, re-used and recycled. Their unique self-repairing properties, the simplicity of their synthesis, their availability from renewable resources and the low cost of raw ingredients (fatty acids and urea) bode well for future applications.

Nanoparticle-Mediated Physical Exfoliation of Aqueous-Phase Graphene for Fabrication of Three-Dimensionally Structured Hybrid Electrodes

PubMed Central

Lee, Younghee; Choi, Hojin; Kim, Min-Sik; Noh, Seonmyeong; Ahn, Ki-Jin; Im, Kyungun; Kwon, Oh Seok; Yoon, Hyeonseok

2016-01-01

Monodispersed polypyrrole (PPy) nanospheres were physically incorporated as guest species into stacked graphene layers without significant property degradation, thereby facilitating the formation of unique three-dimensional hybrid nanoarchitecture. The electrochemical properties of the graphene/particulate PPy (GPPy) nanohybrids were dependent on the sizes and contents of the PPy nanospheres. The nanohybrids exhibited optimum electrochemical performance in terms of redox activity, charge-transfer resistance, and specific capacitance at an 8:1 PPy/graphite (graphene precursor) weight ratio. The packing density of the alternately stacked nanohybrid structure varied with the nanosphere content, indicating the potential for high volumetric capacitance. The nanohybrids also exhibited good long-term cycling stability because of a structural synergy effect. Finally, fabricated nanohybrid-based flexible all–solid state capacitor cells exhibited good electrochemical performance in an acidic electrolyte with a maximum energy density of 8.4 Wh kg−1 or 1.9 Wh L−1 at a maximum power density of 3.2 kW kg−1 or 0.7 kW L−1; these performances were based on the mass or packing density of the electrode materials. PMID:26813878

Phosphorene for energy and catalytic application—filling the gap between graphene and 2D metal chalcogenides

NASA Astrophysics Data System (ADS)

Jain, Rishabh; Narayan, Rekha; Padmajan Sasikala, Suchithra; Lee, Kyung Eun; Jung, Hong Ju; Ouk Kim, Sang

2017-12-01

Phosphorene, a newly emerging graphene analogous 2D elemental material of phosphorous atoms, is unique on the grounds of its natural direct band gap opening, highly anisotropic and extraordinary physical properties. This review highlights the current status of phosphorene research in energy and catalytic applications. The initial part illustrates the typical physical properties of phosphorene, which successfully bridge the prolonged gap between graphene and 2D metal chalcogenides. Various synthetic methods available for black phosphorus (BP) and the exfoliation/growth techniques for single to few-layer phosphorene are also overviewed. The latter part of this review details the working mechanisms and performances of phosphorene/BP in batteries, supercapacitors, photocatalysis, and electrocatalysis. Special attention has been paid to the research efforts to overcome the inherent shortcomings faced by phosphorene based devices. The relevant device performances are compared with graphene and 2D metal chalcogenides based counterparts. Furthermore, the underlying mechanism behind the unstable nature of phosphorene under ambient condition is discussed along with the various approaches to avoid ambient degradation. Finally, comments are offered for the future prospective explorations and outlook as well as challenges lying in the road ahead for phosphorene research.

Incorporation of citrus essential oils into bacterial cellulose-based edible films and assessment of their physical properties

NASA Astrophysics Data System (ADS)

Indrarti, L.; Indriyati

2017-03-01

The use of edible films in food protection and preservation has recently gained more interest since they offer several advantages over synthetic packaging materials. Biocellulose (BC) offers great opportunity as edible film due to their unique physical and mechanical properties. In this study, biocellulose films were prepared by solution casting with addition of 30% carboxymethyl cellulose (CMC) and 30% glycerol as the homogenizer and plasticizer, respectively. Furthermore, various citrus essential oils (EOs) including lemon, lime, and sweet orange were added at 50% w/w of BC dried weight. The solutions were then cast on the tray and allowed to dry in the air convection oven at 40°C overnight. The films were characterized for water solubility, tensile strength (TS), elongation at break (EB), water vapour transmission rate (WVTR), and color. Those characteristics may influence consumer acceptability of the packaged products. Results revealed that addition of lemon and sweet orange EOs into BC-based edible film decreased water solubility and TS, but improved EB, as these oils acted as plasticizers in the film. However, different trend was observed for BC-based film incorporated with lime oil, which had higher solubility and TS, but lower EB and WVTR compared with that of control film. Addition of citrus EOs into BC-based films did not have much effect on color properties as stated in L*, a*, and b* values.

Modifications of Ti-6Al-4V surfaces by direct-write laser machining of linear grooves

NASA Astrophysics Data System (ADS)

Ulerich, Joseph P.; Ionescu, Lara C.; Chen, Jianbo; Soboyejo, Winston O.; Arnold, Craig B.

2007-02-01

As patients who receive orthopedic implants live longer and opt for surgery at a younger age, the need to extend the in vivo lifetimes of these implants has grown. One approach is to pattern implant surfaces with linear grooves, which elicit a cellular response known as contact guidance. Lasers provide a unique method of generating these surface patterns because they are capable of modifying physical and chemical properties over multiple length scales. In this paper we explore the relationship between surface morphology and laser parameters such as fluence, pulse overlap (translation distance), number of passes, and machining environment. We find that using simple procedures involving multiple passes it is possible to manipulate groove properties such as depth, shape, sub-micron roughness, and chemical composition of the Ti-6Al-4V oxide layer. Finally, we demonstrate this procedure by machining several sets of grooves with the same primary groove parameters but varied secondary characteristics. The significance of the secondary groove characteristics is demonstrated by preliminary cell studies indicating that the grooves exhibit basic features of contact guidance and that the cell proliferation in these grooves are significantly altered despite their similar primary characteristics. With further study it will be possible to use specific laser parameters during groove formation to create optimal physical and chemical properties for improved osseointegration.

Synthesis and Properties of Dodecyl Trehaloside Detergents for Membrane Protein Studies

PubMed Central

Tao, Houchao; Fu, Yu; Thompson, Aaron; Lee, Sung Chang; Mahoney, Nicholas; Stevens, Raymond C.; Zhang, Qinghai

2012-01-01

Sugar-based detergents, mostly derived from maltose or glucose, prevail in the extraction, solubilization, stabilization and crystallization of membrane proteins. Inspired by the broad use of trehalose for protecting biological macromolecules and lipid bilayer structures, we synthesized new trehaloside detergents for potential applications in membrane protein research. We devised an efficient synthesis of four dodecyl trehalosides, each with the 12-carboned alkyl chain attached to different hydroxyl groups of trehalose, thus presenting a structurally diverse but related family of detergents. The detergent physical properties, including solubility, hydrophobicity, critical micelle concentration (CMC) and size of micelles, were evaluated and compared with the most popular maltoside analog, β- D-dodecylmaltoside (DDM), which varied from each other due to distinct molecular geometries and possible polar group interactions in resulting micelles. Crystals of 2-dodecyl trehaloside (2-DDTre) were also obtained in methanol, and the crystal packing revealed multiple H-bonded interactions among adjacent trehalose groups. The few trehaloside detergents were tested for the solubilization and stabilization of the nociceptin/orphanin FQ peptide receptor (ORL1) and MsbA, which belong to the G-protein coupled receptor (GPCR) and ATP-binding cassette transporter families, respectively. Our results demonstrated the utility of trehaloside detergents as membrane protein solubilization reagents with the optimal detergents being protein dependent. Continuing development and investigations of trehaloside detergents are attractive given their interesting and unique chemical-physical properties and potential interactions with membrane lipids. PMID:22780816

ASSESSING THE EFFECTS OF PULMONARY EXPOSURE TO NANOMATERIALS

EPA Science Inventory

Nanotechnology is a dynamic and enabling technology capable of producing a wide diversity of nano-scale (<100 nm) materials displaying unique physicochemical properties for a variety of applications. Nanomaterials may also display unique toxicological properties and routes of exp...

RISK ASSESSMENT OF MANUFACTURED NANOMATERIAL: MORE THAN JUST SIZE

EPA Science Inventory

Nanotechnology is a dynamic and enabling technology capable of producing nano-scale materials with unique electrical, catalytic, thermal, mechanical, or imaging properties for a variety of applications. Nanomaterials may display unique toxicological properties and routes of expos...

Bio-inspired layered chitosan/graphene oxide nanocomposite hydrogels with high strength and pH-driven shape memory effect.

PubMed

Zhang, Yaqian; Zhang, Min; Jiang, Haoyang; Shi, Jinli; Li, Feibo; Xia, Yanhong; Zhang, Gongzheng; Li, Huanjun

2017-12-01

The layered nanocomposite hydrogel films containing chitosan (CS) and graphene oxide (GO) have been prepared by water evaporation induced self-assembly and subsequent physical cross-linking in alkaline solution. The layered CS/GO hydrogel films obtained have a nacre-like brick-and-mortar microstructure, which contributes to their excellent mechanical properties. The tensile strength and elongation at break of the hydrogel films with 5wt% GO are 5.35MPa and 193.5%, respectively, which are comparable to natural costal cartilage. Furthermore, the CS/GO hydrogel films exhibited pH-driven shape memory effect, and this unique phenomenon is mainly attributed to the reversible transition of partial physically cross-linking corresponding to hydrogen bondings and hydrophobic interactions between CS polymer chains due to pH changing. Copyright © 2017 Elsevier Ltd. All rights reserved.

Stochastic Modeling and Generation of Partially Polarized or Partially Coherent Electromagnetic Waves

NASA Technical Reports Server (NTRS)

Davis, Brynmor; Kim, Edward; Piepmeier, Jeffrey; Hildebrand, Peter H. (Technical Monitor)

2001-01-01

Many new Earth remote-sensing instruments are embracing both the advantages and added complexity that result from interferometric or fully polarimetric operation. To increase instrument understanding and functionality a model of the signals these instruments measure is presented. A stochastic model is used as it recognizes the non-deterministic nature of any real-world measurements while also providing a tractable mathematical framework. A stationary, Gaussian-distributed model structure is proposed. Temporal and spectral correlation measures provide a statistical description of the physical properties of coherence and polarization-state. From this relationship the model is mathematically defined. The model is shown to be unique for any set of physical parameters. A method of realizing the model (necessary for applications such as synthetic calibration-signal generation) is given and computer simulation results are presented. The signals are constructed using the output of a multi-input multi-output linear filter system, driven with white noise.

Variability of the solar shape (before space dedicated missions)

NASA Astrophysics Data System (ADS)

Rozelot, J. P.; Damiani, C.; Lefebvre, S.

2009-12-01

Shrinking or expansion of the solar shape and irradiance variations are ultimately related to solar activity. We give here a review on existing ground-based or space solar radius measurements, extending the concept to shape changes. We show how helioseismology results allow us to look at the variations below the surface, where changes are not uniform, putting in evidence a new shallow layer, the leptocline, which is the seat of solar asphericities, radius variations with the 11-yr cycle and the cradle of complex physical processes: partial ionization of the light elements, opacities changes, superadiabaticity, strong gradient of rotation and pressure. Based on such physical grounds, we show why it is important to get accurate measurements from scheduled dedicated space missions: PICARD, SDO, DynaMICCS, ASTROMETRIA, SPHERIS. Such measurements will provide us a unique opportunity to study in detail the relationship between global solar properties and changes in the Sun's interior.

Probing viscoelastic surfaces with bimodal tapping-mode atomic force microscopy: Underlying physics and observables for a standard linear solid model

PubMed Central

2014-01-01

Summary This paper presents computational simulations of single-mode and bimodal atomic force microscopy (AFM) with particular focus on the viscoelastic interactions occurring during tip–sample impact. The surface is modeled by using a standard linear solid model, which is the simplest system that can reproduce creep compliance and stress relaxation, which are fundamental behaviors exhibited by viscoelastic surfaces. The relaxation of the surface in combination with the complexities of bimodal tip–sample impacts gives rise to unique dynamic behaviors that have important consequences with regards to the acquisition of quantitative relationships between the sample properties and the AFM observables. The physics of the tip–sample interactions and its effect on the observables are illustrated and discussed, and a brief research outlook on viscoelasticity measurement with intermittent-contact AFM is provided. PMID:25383277

Physical Orbit for Lam Vir and Testing of Stellar Evolution Models

NASA Astrophysics Data System (ADS)

Zhao, M.; Monnier, J. D.; Torres, G.; Pedretti, E.; Millan-Gabet, R.; Berger, J.-P.; Traub, W. A.; Schloerb, F. P.

2005-12-01

Lambda Virginis is a well-known double-lined spectroscopic Am binary with the interesting property that both stars are very similar in abundance but one is sharp-lined and the other is broad-lined. The differing rotation rates and the unusual metallic-lined nature of this system presents a unique opportunity to test stellar evolution models. In this poster, we present high resolution observations of Lam Vir, taken with the Infrared-Optical Telescopes Array (IOTA) between 2003 and 2005. By combining our interferometric data with double-lined radial velocity data, we determined for the first time the physical orbit of Lam Vir, as well as the orbital parallax of the system. In addition, the masses of the two components are determined with 1% and 1.5% errors respectively. Our preliminary result from comparison with stellar evolution models suggests a discrepancy between Lam Vir and standard models.

Nuclear-Structure Physics with MINIBALL at HIE-ISOLDE

NASA Astrophysics Data System (ADS)

Reiter, P.; MINIBALL Collaboration

2018-02-01

The MINIBALL spectrometer utilizes successfully a variety of post-accelerated radioactive ion beams provided by the new HIE-ISOLDE accelerator at CERN. In-beam γ-ray spectroscopy after Coulomb excitation (CE) or transfer reactions is performed with optimized setups of ancillary detectors for particle detection. The physics program covers a wide range of shell model investigations. Exotic heavy ion beams will enable unique studies of collective properties up to the actinide region. First data taking with HIE-ISOLDE beams started recently. The higher energies and intensities of the new post-accelerator provides a promising perspective for a new generation of MINIBALL experiments. Intriguing first results were obtained by employing beams of 74,76,78Zn, 110,132Sn, 144Xe with beam energies in the range of 4.0 - 5.5 MeV/u for CE experiments at ‘safe’ energies. In all cases first results for various B(Eλ) values for these isotopes were obtained.

Proton therapy in clinical practice

PubMed Central

Liu, Hui; Chang, Joe Y.

2011-01-01

Radiation dose escalation and acceleration improves local control but also increases toxicity. Proton radiation is an emerging therapy for localized cancers that is being sought with increasing frequency by patients. Compared with photon therapy, proton therapy spares more critical structures due to its unique physics. The physical properties of a proton beam make it ideal for clinical applications. By modulating the Bragg peak of protons in energy and time, a conformal radiation dose with or without intensity modulation can be delivered to the target while sparing the surrounding normal tissues. Thus, proton therapy is ideal when organ preservation is a priority. However, protons are more sensitive to organ motion and anatomy changes compared with photons. In this article, we review practical issues of proton therapy, describe its image-guided treatment planning and delivery, discuss clinical outcome for cancer patients, and suggest challenges and the future development of proton therapy. PMID:21527064

Spitzer observations of two mission-accessible, tiny asteroids

NASA Astrophysics Data System (ADS)

Mommert, M.; Hora, J.; Farnocchia, D.; Chesley, S.; Vokrouhlicky, D.; Trilling, D.; Mueller, M.; Harris, A.; Smith, H.; Fazio, G.

2014-07-01

Small asteroids are most likely collisional fragments of larger objects and make up a large fraction of the near-Earth-object (NEO) population. Despite their abundance, little is known about the physical properties of these objects, which is mainly due to their faintness, which also impedes their discovery. We report on Spitzer Space Telescope observations of two small NEOs, both of which are of interest as potential spacecraft targets. We observed NEOs 2009 BD using 25 hrs and 2011 MD using ˜20 hrs of Spitzer Infrared Array Camera Channel 2 time. For each target, we have combined the data into maps in the moving frame of the target, minimizing the background confusion. We did not detect 2009 BD and place an upper limit on its flux density, but we detected 2011 MD as a 2.2σ detection. We have analyzed the data on both objects in a combined model approach, using an asteroid thermophysical model and a model of non-gravitational forces acting on the object. As a result, we are able to constrain the physical properties of both objects. In the case of 2009 BD (Mommert et al. 2014), a wealth of existing astrometry data significantly constrains the physical properties of the object. We find two physically possible solutions. The first solution shows 2009 BD as a 2.9±0.3 m-sized massive rock body (bulk density ρ=2.9±0.5 g cm^{-3}) with an extremely high albedo of 0.85_{-0.10}^{+0.20} that is covered with regolith-like material, causing it to exhibit a low thermal inertia (thermal inertia Γ=30_{-10}^{+20} SI units). The second solution suggests 2009 BD to be a 4±1 m-sized asteroid with p_{V}=0.45_{-0.15}^{+0.35} that consists of a collection of individual bare rock slabs (Γ = 2000±1000 SI units, ρ = 1.7_{-0.4}^{+0.7} g cm^{-3}). We are unable to rule out either solution based on physical reasoning. The preliminary analysis of 2011 MD shows this object as a ˜6 m-sized asteroid with an albedo of ˜0.3. Additional constraints on the physical properties of these objects will be available at the time of the conference (Mommert et al., in preparation). 2009 BD and 2011 MD are the smallest asteroids for which physical properties have been constrained, providing unique insights into a population of asteroids that gives rise to frequent impacts on the Earth and the Moon. Furthermore, both asteroids are among the most easily accessible objects in space.

Constraining the Bulk Density of 10m-Class Near-Earth Asteroid 2012 LA

NASA Astrophysics Data System (ADS)

Mommert, Michael; Hora, Joseph; Farnocchia, Davide; Trilling, David; Chesley, Steve; Harris, Alan; Mueller, Migo; Smith, Howard

2016-08-01

The physical properties of near-Earth asteroids (NEAs) provide important hints on their origin, as well as their past physical and orbital evolution. Recent observations seem to indicate that small asteroids are different than expected: instead of being monolithic bodies, some of them instead resemble loose conglomerates of smaller rocks, so called 'rubble piles'. This is surprising, since self-gravitation is practically absent in these bodies. Hence, bulk density measurements of small asteroids, from which their internal structure can be estimated, provide unique constraints on asteroid physical models, as well as models for asteroid evolution. We propose Spitzer Space Telescope observations of 10 m-sized NEA 2012 LA, which will allow us to constrain the diameter, albedo, bulk density, macroporosity, and mass of this object. We require 30 hrs of Spitzer time to detect our target with a minimum SNR of 3 in CH2. In order to interpret our observational results, we will use the same analysis technique that we used in our successful observations and analyses of tiny asteroids 2011 MD and 2009 BD. Our science goal, which is the derivation of the target's bulk density and its internal structure, can only be met with Spitzer. Our observations will produce only the third comprehensive physical characterization of an asteroid in the 10m size range (all of which have been carried out by our team, using Spitzer). Knowledge of the physical properties of small NEAs, some of which pose an impact threat to the Earth, is of importance for understanding their evolution and estimating the potential of destruction in case of an impact, as well as for potential manned missions to NEAs for either research or potential commercial uses.

Biocompatibility Assessment of Si-based Nano- and Micro-particles

PubMed Central

Jaganathan, Hamsa; Godin, Biana

2012-01-01

Silicon is one of the most abundant chemical elements found on the Earth. Due to its unique chemical and physical properties, silicon based materials and their oxides (e.g. silica) have been used in several industries such as building and construction, electronics, food industry, consumer products and biomedical engineering/medicine. This review summarizes studies on effects of silicon and silica nano- and micro-particles on cells and organs following four main exposure routes, namely, intravenous, pulmonary, dermal and oral. Further, possible genotoxic effects of silica based nanoparticles are discussed. The review concludes with an outlook on improving and standardizing biocompatibility assessment for nano- and micro-particles. PMID:22634160

The recent progress of isoxazole in medicinal chemistry.

PubMed

Zhu, Jie; Mo, Jun; Lin, Hong-Zhi; Chen, Yao; Sun, Hao-Peng

2018-05-28

Isoxazole compounds exhibit a wide spectrum of targets and broad biological activities. Developing compounds with heterocycle rings has been one of the trends. The integration of isoxazole ring can offer improved physical-chemical properties. Because of the unique profiles, isoxazole ring becomes a popular moiety in compounds design. In this review article, the major focus has been paid to the applications of isoxazole compounds in treating multiple diseases, including anticancer, antimicrobial, anti-inflammatory, etc. Strategies for compounds design for preclinical, clinical, and FDA approved drugs were discussed. Also, the emphasis has been addressed to the future perspectives and trend for the application. Copyright © 2018 Elsevier Ltd. All rights reserved.

The AGATA Campaign at GANIL

NASA Astrophysics Data System (ADS)

Lenzi, Silvia M.; Clement, Emmanuel

2018-02-01

The Advanced Gamma Tracking Array, AGATA, is presently in its construction phase in which the European γ-spectroscopy research community is involved since several years. This powerful HPGe array offers unique possibilities for the study of rare phenomena in nuclei by detailed gamma-ray spectroscopy. The physics campaign in GANIL foresees different setups, with AGATA coupled to different spectrometers, to study nuclear structure properties of nuclei all across the nuclear chart, from light nuclei to very heavy species, using stable and radioactive beams. After a brief description of the AGATA concept, some recent results are presented together with the very interesting opportunities for nuclear structure research in the forthcoming years with AGATA at GANIL.

Penetration of Solar Radiation into Solid Carbon Dioxide

NASA Astrophysics Data System (ADS)

Chinnery, H. E.; Hagermann, A.; Kaufmann, E.; Lewis, S. R.; Grady, M. M.

2017-09-01

Carbon dioxide ice exists naturally on the surface of Mars. This is a unique environment, with no Earth analogues, and so determining the properties of such a surface is important to further our understanding of the Martian environment. Laboratory experiments have determined the e-folding scale, or absorption scale length, for carbon dioxide slab ice, granular ice and snow. This is a universal measure of how transparent a material is to visible light, and so has implications for the radiative budget of carbon dioxide ice covered surfaces, as well as physical processes, such as the so-called spider formations in the cryptic region near the Martian south pole.

Fabrication of ultralong hybrid microfibers from nanosheets of reduced graphene oxide and transition-metal dichalcogenides and their application as supercapacitors.

PubMed

Sun, Gengzhi; Liu, Juqing; Zhang, Xiao; Wang, Xuewan; Li, Hai; Yu, Yang; Huang, Wei; Zhang, Hua; Chen, Peng

2014-11-10

Two-dimensional materials have attracted increasing research interest owing to their unique electronic, physical, optical, and mechanical properties. We thus developed a general strategy for the fabrication of ultralong hybrid microfibers from a mixture of reduced graphene oxide and transition-metal dichalcogenides (TMDs), including MoS2 , TiS2 , TaS2 , and NbSe2 . Furthermore, we prepared fiber-based solid-state supercapacitors as a proof-of-concept application. The performance of thus-prepared supercapacitors was greatly improved by the introduction of the TMDs. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

SOFIA: On the Pathway toward Habitable Worlds

NASA Astrophysics Data System (ADS)

Gehrz, R. D.; Angerhausen, D.; Becklin, E. E.; Greenhouse, M. A.; Horner, S.; Krabbe, A.; Swain, M. R.; Young, E. T.

2010-10-01

The U.S./German Stratospheric Observatory for Infrared Astronomy (SOFIA), a 2.5-meter infrared airborne telescope in a Boeing 747-SP, will conduct 0.3 - 1,600 μm photometric, spectroscopic, and imaging observations from altitudes as high as 45,000 ft., where the average atmospheric transmission is greater than 80 percent. SOFIA’s first light cameras and spectrometers, as well as future generations of instruments, will enable SOFIA to make unique contributions to the characterization of the physical properties of proto-planetary disks around young stellar objects and of the atmospheres of exoplanets that transit their parent stars. We describe several types of experiments that are being contemplated.

Tuning topological phases in the XMnSb2 system via chemical substitution from first principles

NASA Astrophysics Data System (ADS)

Griffin, Sinead M.; Neaton, Jeffrey B.

New Dirac materials are sought for their interesting fundamental physics and for their potential technological applications. Protected symmetries offer a route to potential zero mass Dirac and Weyl fermions, and can lead unique transport properties and spectroscopic signatures. In this work, we use first-principles calculations to study the XMnSb2 family of materials and show how varying X changes the nature of bulk protected topological features in their electronic structure. We further discuss new design rules for predicting new topological materials suggested by our calculations. SG is supported by the Early Postdoc Mobility Fellowship of the SNF.

Sapphire shaped crystals for laser-assisted cryodestruction of biological tissues

NASA Astrophysics Data System (ADS)

Shikunova, I. A.; Dubyanskaya, E. N.; Kuznetsov, A. A.; Katyba, G. M.; Dolganova, I. N.; Mukhina, E. E.; Chernomyrdin, N. V.; Zaytsev, K. I.; Tuchin, V. V.; Kurlov, V. N.

2018-04-01

We have developed cryo-applicators based on the sapphire shaped crystals fabricated using the edge-defined film-fed growth (EFG) and noncapillary shaping (NCS) techniques. Due to the unique physical properties of sapphire: i.e. high thermal, mechanical, and chemical strength, impressive thermal conductivity and optical transparency, these cryo-applicators yield combination of the tissue cryo-destruction with its exposure to laser radiation for controlling the thermal regimes of cryosurgery, and with the optical diagnosis of tissue freezing. We have applied the proposed sapphire cryo-applicators for the destruction of tissues in vitro. The observed results highlight the prospectives of the sapphire cryo-applicators in cryosurgery.

Fluorescent nanoparticles based on AIE fluorogens for bioimaging.

PubMed

Yan, Lulin; Zhang, Yan; Xu, Bin; Tian, Wenjing

2016-02-07

Fluorescent nanoparticles (FNPs) have recently attracted increasing attention in the biomedical field because of their unique optical properties, easy fabrication and outstanding performance in imaging. Compared with conventional molecular probes including small organic dyes and fluorescent proteins, FNPs based on aggregation-induced emission (AIE) fluorogens have shown significant advantages in tunable emission and brightness, good biocompatibility, superb photo- and physical stability, potential biodegradability and facile surface functionalization. In this review, we summarize the latest advances in the development of fluorescent nanoparticles based on AIE fluorogens including polymer nanoparticles and silica nanoparticles over the past few years, and the various biomedical applications based on these fluorescent nanoparticles are also elaborated.

A complete catalog of stellar mass maps for PHANGS

NASA Astrophysics Data System (ADS)

Munoz-Mateos, Juan-Carlos; Querejeta, Miguel; Schinnerer, Eva; Leroy, Adam; Sun, Jiayi; Blanc, Guillermo; Kruijssen, Diederik; Emsellem, Eric; Bigiel, Frank

2018-05-01

We request IRAC 3.6 and 4.5 um imaging of four galaxies that have been mapped in molecular gas by ALMA as part of its first large program targeting nearby galaxies (PHANGS: Physics at High Angular resolution in Nearby GalaxieS). IRAC provides a uniquely robust view of the stellar mass distribution, which in turn plays a key role in regulating the properties and behavior of the molecular gas. These are the only targets of our ALMA large program without such imaging. A modest investment of Spitzer time will allow us to measure the drivers of molecular cloud and star formation in these targets.

Current molecular and emerging nanobiotechnology approaches for the detection of microbial pathogens.

PubMed

Theron, Jacques; Eugene Cloete, Thomas; de Kwaadsteniet, Michele

2010-11-01

Waterborne microbial diseases are escalating worldwide increasing the need for powerful and sensitive diagnostics tools. Molecular methodologies, including immunological and nucleic acid-based methods, have only recently been applied in the water sector. Advances in nanotechnology and nanomaterials have opened the door for the development of new diagnostic tools with increased sensitivity and speed, and reduced cost and labor. Quantum dots, flo dots, gold nanoparticles, magnetic nanoparticles, carbon nanotubes, nanowires, and nanocantilevers, with their unique optical and physical properties, have already been applied in nanodiagnostics. Nanobiotechnology, once remaining technical and practical problems has been addressed, will play an important role in the detection of microbial pathogens.

Quantitative flow and velocity measurements of pulsatile blood flow with 4D-DSA

NASA Astrophysics Data System (ADS)

Shaughnessy, Gabe; Hoffman, Carson; Schafer, Sebastian; Mistretta, Charles A.; Strother, Charles M.

2017-03-01

Time resolved 3D angiographic data from 4D DSA provides a unique environment to explore physical properties of blood flow. Utilizing the pulsatility of the contrast waveform, the Fourier components can be used to track the waveform motion through vessels. Areas of strong pulsatility are determined through the FFT power spectrum. Using this method, we find an accuracy from 4D-DSA flow measurements within 7.6% and 6.8% RMSE of ICA PCVIPR and phantom flow probe validation measurements, respectively. The availability of velocity and flow information with fast acquisition could provide a more quantitative approach to treatment planning and evaluation in interventional radiology.

The concept of the CCN protein family revisited: a centralized coordination network.

PubMed

Perbal, Bernard

2018-03-01

The wide array of biological properties attributed to the CCN family of proteins (Perbal in Lancet 363(9402):62-64, 2004) led me to reconsider the possible relationship and roles that these proteins may play as a team, instead of acting on their own as individual regulators in various signaling pathways. The dynamic model which I present in this review stems from the contribution of the biological properties that we established for CCN3, one of the three founding members of the CCN family, which was identified by our group as the first CCN protein showing growth inhibitory properties (1992), expressed mainly in quiescent cells (1996), and showing anti-tumor activities in several cellular models both ex vivo and in vivo. At the present time CCN3 is the only member of the family that has been reported to negatively act on the progression of the cell cycle. The unique dual localisation of CCN3 in the nucleus and outside cells, either at the membrane or in the extracellular matrix, that I first established in 1999, and that now appears to be shared by several other CCN proteins, is a unique essential feature which can no longer be ignored. Based on the structural and functional properties of CCN3, shared by most of the CCN family members, I propose an « all in one » concept in which CCN proteins are team members with specific functions that are aimed at the same goal. This model accounts both for the functional specificity of the various CCN proteins, their sequential and opposite or complementary effects in various biological context, and for the biological consequences of their physical interaction and biological cross-regulation.

Optically pumped VECSELs: review of technology and progress

NASA Astrophysics Data System (ADS)

Guina, M.; Rantamäki, A.; Härkönen, A.

2017-09-01

Vertical-external-cavity surface-emitting lasers (VECSELs) are the most versatile laser sources, combining unique features such as wide spectral coverage, ultrashort pulse operation, low noise properties, high output power, high brightness and compact form-factor. This paper reviews the recent technological developments of VECSELs in connection with the new milestones that continue to pave the way towards their use in numerous applications. Significant attention is devoted to the fabrication of VECSEL gain mirrors in challenging wavelength regions, especially at the yellow and red wavelengths. The reviewed fabrication approaches address wafer-bonded VECSEL structures as well as the use of hybrid mirror structures. Moreover, a comprehensive summary of VECSEL characterization methods is presented; the discussion covers different stages of VECSEL development and different operation regimes, pointing out specific characterization techniques for each of them. Finally, several emerging applications are discussed, with emphasis on the unique application objectives that VECSELs render possible, for example in atom and molecular physics, dermatology and spectroscopy.

Chances and limitations of nanosized titanium dioxide practical application in view of its physicochemical properties

NASA Astrophysics Data System (ADS)

Bogdan, Janusz; Jackowska-Tracz, Agnieszka; Zarzyńska, Joanna; Pławińska-Czarnak, Joanna

2015-02-01

Nanotechnology is a field of science that is nowadays developing in a dynamic way. It seems to offer almost endless opportunities of contribution to many areas of economy and human activity, in general. Thanks to nanotechnology, the so-called nanomaterials can be designed. They present structurally altered materials, with their physical, chemical and biological properties entirely differing from properties of the same materials manufactured in microtechnology. Nanotechnology creates a unique opportunity to modify the matter at the level of atoms and particles. Therefore, it has become possible to obtain items displaying new, useful properties, i.e. self-disinfecting and self-cleaning surfaces. Those surfaces are usually covered by a thin layer of a photocatalyst. The role of the photocatalyst is most of the time performed by the nanosized titanium dioxide (nano-TiO2). Excitation of nano-TiO2 by ultraviolet radiation initiates advanced oxidation processes and reactions leading to the creation of oxygen vacancies that bind water particles. As a result, photocatalytic surfaces are given new properties. Those properties can then be applied in a variety of disciplines, such as medicine, food hygiene, environmental protection or building industry. Practically, the applications include inactivation of microorganisms, degradation of toxins, removing pollutants from buildings and manufacturing of fog-free windows or mirrors.

Electronic and optical properties of strained graphene and other strained 2D materials: a review.

PubMed

Naumis, Gerardo G; Barraza-Lopez, Salvador; Oliva-Leyva, Maurice; Terrones, Humberto

2017-09-01

This review presents the state of the art in strain and ripple-induced effects on the electronic and optical properties of graphene. It starts by providing the crystallographic description of mechanical deformations, as well as the diffraction pattern for different kinds of representative deformation fields. Then, the focus turns to the unique elastic properties of graphene, and to how strain is produced. Thereafter, various theoretical approaches used to study the electronic properties of strained graphene are examined, discussing the advantages of each. These approaches provide a platform to describe exotic properties, such as a fractal spectrum related with quasicrystals, a mixed Dirac-Schrödinger behavior, emergent gravity, topological insulator states, in molecular graphene and other 2D discrete lattices. The physical consequences of strain on the optical properties are reviewed next, with a focus on the Raman spectrum. At the same time, recent advances to tune the optical conductivity of graphene by strain engineering are given, which open new paths in device applications. Finally, a brief review of strain effects in multilayered graphene and other promising 2D materials like silicene and materials based on other group-IV elements, phosphorene, dichalcogenide- and monochalcogenide-monolayers is presented, with a brief discussion of interplays among strain, thermal effects, and illumination in the latter material family.

Nickel-Titanium Alloys: Corrosion "Proof" Alloys for Space Bearing, Components and Mechanism Applications

NASA Technical Reports Server (NTRS)

DellaCorte, Christopher

2010-01-01

An intermetallic nickel-titanium alloy, 60NiTi (60 wt% Ni, 40 wt% Ti), is shown to be a promising candidate tribological material for space mechanisms. 60NiTi offers a broad combination of physical properties that make it unique among bearing materials. 60NiTi is hard, electrically conductive, highly corrosion resistant, readily machined prior to final heat treatment, and is non-magnetic. Despite its high Ti content, 60NiTi is non-galling even under dry sliding. No other bearing alloy, metallic or ceramic, encompasses all of these attributes. Since 60NiTi contains such a high proportion of Ti and possesses many metallic properties, it was expected to exhibit poor tribological performance typical of Ti alloys, namely galling type behavior and rapid lubricant degradation. In this poster-paper, the oil-lubricated behavior of 60NiTi is presented.

Nickel-Titanium Alloys: Corrosion "Proof" Alloys for Space Bearing, Components and Mechanism Applications

NASA Technical Reports Server (NTRS)

DellaCorte, Christopher

2010-01-01

An intermetallic nickel-titanium alloy, 60NiTi (60wt%Ni, 40wt%Ti), is shown to be a promising candidate tribological material for space mechanisms. 60NiTi offers a broad combination of physical properties that make it unique among bearing materials. 60NiTi is hard, electrically conductive, highly corrosion resistant, readily machined prior to final heat treatment, and is non-magnetic. Despite its high titanium content, 60NiTi is non-galling even under dry sliding. No other bearing alloy, metallic or ceramic, encompasses all of these attributes. Since 60NiTi contains such a high proportion of titanium and possesses many metallic properties, it was expected to exhibit poor tribological performance typical of titanium alloys, namely galling type behavior and rapid lubricant degradation. In this poster-paper, the oil-lubricated behavior of 60NiTi is studied.

Effect of ammonia and methane adsorption on the electronic structure of undoped and Fe-doped 2D silica: a first-principles calculation

NASA Astrophysics Data System (ADS)

Chibisov, A. N.; Chibisova, M. A.

2018-05-01

Two-dimensional silicon oxide (2D SiO2) is a unique surface phase with interesting optical, structural and electronic properties. In this study, important novel results on the effect of Fe on the structural and electronic properties of 2D SiO2 during adsorption of CH4 and NH3 molecules are presented. Density functional theory calculations are used to investigate the interaction of CH4 and NH3 molecules with silica. The electronic structure and molecules adsorption energy are studied in detail for undoped and Fe-doped surfaces. The results show that adsorption of CH4 and NH3 molecules on the surface decreases the spin polarization of Fe/SiO2. The results are relevant to understanding the adsorption physics of 2D SiO2 for practical usage in modern nanoelectronic sensors for nanotechnology and optoelectronics.

Characterization of TEM Moiré Patterns Originating from Two Monolayer Graphenes Grown on the Front and Back Sides of a Copper Substrate by CVD Method

NASA Astrophysics Data System (ADS)

Yamazaki, Kenji; Maehara, Yosuke; Gohara, Kazutoshi

2018-06-01

The number of layers affects the electronic properties of graphene owing to its unique band structure, called the Dirac corn. Raman spectroscopy is a key diagnostic tool for identifying the number of graphene layers and for determining their physical properties. Here, we observed moiré structures in transmission electron microscopy (TEM) observations; these are signature patterns in multilayer, although Raman spectra showed the typical intensity of the 2D/G peak in the monolayer. We also performed a multi-slice TEM image simulation to compare the 3D atomic structures of the two graphene membranes with experimental TEM images. We found that the experimental moiré image was constructed with a 9-12 Å interlayer distance between graphene membranes. This structure was constructed by transferring CVD-grown graphene films that formed on both sides of the Cu substrate at once.

Supported lipid bilayer/carbon nanotube hybrids

NASA Astrophysics Data System (ADS)

Zhou, Xinjian; Moran-Mirabal, Jose M.; Craighead, Harold G.; McEuen, Paul L.

2007-03-01

Carbon nanotube transistors combine molecular-scale dimensions with excellent electronic properties, offering unique opportunities for chemical and biological sensing. Here, we form supported lipid bilayers over single-walled carbon nanotube transistors. We first study the physical properties of the nanotube/supported lipid bilayer structure using fluorescence techniques. Whereas lipid molecules can diffuse freely across the nanotube, a membrane-bound protein (tetanus toxin) sees the nanotube as a barrier. Moreover, the size of the barrier depends on the diameter of the nanotube-with larger nanotubes presenting bigger obstacles to diffusion. We then demonstrate detection of protein binding (streptavidin) to the supported lipid bilayer using the nanotube transistor as a charge sensor. This system can be used as a platform to examine the interactions of single molecules with carbon nanotubes and has many potential applications for the study of molecular recognition and other biological processes occurring at cell membranes.

Cellulose Nanomaterials in Water Treatment Technologies

PubMed Central

Carpenter, Alexis Wells; de Lannoy, Charles François; Wiesner, Mark R.

2015-01-01

Cellulose nanomaterials are naturally occurring with unique structural, mechanical and optical properties. While the paper and packaging, automotive, personal care, construction, and textiles industries have recognized cellulose nanomaterials’ potential, we suggest cellulose nanomaterials have great untapped potential in water treatment technologies. In this review, we gather evidence of cellulose nanomaterials’ beneficial role in environmental remediation and membranes for water filtration, including their high surface area-to-volume ratio, low environmental impact, high strength, functionalizability, and sustainability. We make direct comparison between cellulose nanomaterials and carbon nanotubes (CNTs) in terms of physical and chemical properties, production costs, use and disposal in order to show the potential of cellulose nanomaterials as a sustainable replacement for CNTs in water treatment technologies. Finally, we comment on the need for improved communication and collaboration across the myriad industries invested in cellulose nanomaterials production and development to achieve an efficient means to commercialization. PMID:25837659

The XMM-Newton View of Wolf-Rayet Bubbles

NASA Astrophysics Data System (ADS)

Guerrero, M.; Toala, J.

2017-10-01

The powerful stellar winds of Wolf-Rayet (WR) stars blow large bubble into the circumstellar material ejected in previous phases of stellar evolution. The shock of those stellar winds produces X-ray-emitting hot plasmas which tells us about the diffusion of processed material onto the interstellar medium, about processes of heat conduction and turbulent mixing at the interface, about the late stages of stellar evolution, and about the shaping of the circumstellar environment, just before supernova explosions. The unique sensitivity of XMM-Newton has been key for the detection, mapping and spectral analysis of the X-ray emission from the hot bubbles around WR stars. These observations underscore the importance of the structure of the interstellar medium around massive stars, but they have also unveiled unknown phenomena, such as blowouts of hot gas into the interstellar medium or spatially-resolved spectral properties of the hot gas, which disclose inhomogeneous chemical abundances and physical properties across these bubbles.

Potential for Remotely Sensed Soil Moisture Data in Hydrologic Modeling

NASA Technical Reports Server (NTRS)

Engman, Edwin T.

1997-01-01

Many hydrologic processes display a unique signature that is detectable with microwave remote sensing. These signatures are in the form of the spatial and temporal distributions of surface soil moisture and portray the spatial heterogeneity of hydrologic processes and properties that one encounters in drainage basins. The hydrologic processes that may be detected include ground water recharge and discharge zones, storm runoff contributing areas, regions of potential and less than potential ET, and information about the hydrologic properties of soils and heterogeneity of hydrologic parameters. Microwave remote sensing has the potential to detect these signatures within a basin in the form of volumetric soil moisture measurements in the top few cm. These signatures should provide information on how and where to apply soil physical parameters in distributed and lumped parameter models and how to subdivide drainage basins into hydrologically similar sub-basins.

Imaging spectroscopy of solar radio burst fine structures.

PubMed

Kontar, E P; Yu, S; Kuznetsov, A A; Emslie, A G; Alcock, B; Jeffrey, N L S; Melnik, V N; Bian, N H; Subramanian, P

2017-11-15

Solar radio observations provide a unique diagnostic of the outer solar atmosphere. However, the inhomogeneous turbulent corona strongly affects the propagation of the emitted radio waves, so decoupling the intrinsic properties of the emitting source from the effects of radio wave propagation has long been a major challenge in solar physics. Here we report quantitative spatial and frequency characterization of solar radio burst fine structures observed with the Low Frequency Array, an instrument with high-time resolution that also permits imaging at scales much shorter than those corresponding to radio wave propagation in the corona. The observations demonstrate that radio wave propagation effects, and not the properties of the intrinsic emission source, dominate the observed spatial characteristics of radio burst images. These results permit more accurate estimates of source brightness temperatures, and open opportunities for quantitative study of the mechanisms that create the turbulent coronal medium through which the emitted radiation propagates.

Advances in imaging and quantification of electrical properties at the nanoscale using Scanning Microwave Impedance Microscopy (sMIM)

NASA Astrophysics Data System (ADS)

Friedman, Stuart; Stanke, Fred; Yang, Yongliang; Amster, Oskar

Scanning Microwave Impedance Microscopy (sMIM) is a mode for Atomic Force Microscopy (AFM) enabling imaging of unique contrast mechanisms and measurement of local permittivity and conductivity at the 10's of nm length scale. sMIM has been applied to a variety of systems including nanotubes, nanowires, 2D materials, photovoltaics and semiconductor devices. Early results were largely semi-quantitative. This talk will focus on techniques for extracting quantitative physical parameters such as permittivity, conductivity, doping concentrations and thin film properties from sMIM data. Particular attention will be paid to non-linear materials where sMIM has been used to acquire nano-scale capacitance-voltage curves. These curves can be used to identify the dopant type (n vs p) and doping level in doped semiconductors, both bulk samples and devices. Supported in part by DOE-SBIR DE-SC0009856.

Advances in imaging and quantification of electrical properties at the nanoscale using Scanning Microwave Impedance Microscopy (sMIM)

NASA Astrophysics Data System (ADS)

Friedman, Stuart; Yang, Yongliang; Amster, Oskar

2015-03-01

Scanning Microwave Impedance Microscopy (sMIM) is a mode for Atomic Force Microscopy (AFM) enabling imaging of unique contrast mechanisms and measurement of local permittivity and conductivity at the 10's of nm length scale. Recent results will be presented illustrating high-resolution electrical features such as sub 15 nm Moire' patterns in Graphene, carbon nanotubes of various electrical states and ferro-electrics. In addition to imaging, the technique is suited to a variety of metrology applications where specific physical properties are determined quantitatively. We will present research activities on quantitative measurements using multiple techniques to determine dielectric constant (permittivity) and conductivity (e.g. dopant concentration) for a range of materials. Examples include bulk dielectrics, low-k dielectric thin films, capacitance standards and doped semiconductors. Funded in part by DOE SBIR DE-SC0009586.

Gold and silver nanoparticles conjugated with heparin derivative possess anti-angiogenesis properties

NASA Astrophysics Data System (ADS)

Kemp, Melissa M.; Kumar, Ashavani; Mousa, Shaymaa; Dyskin, Evgeny; Yalcin, Murat; Ajayan, Pulickel; Linhardt, Robert J.; Mousa, Shaker A.

2009-11-01

Silver and gold nanoparticles display unique physical and biological properties that have been extensively studied for biological and medical applications. Typically, gold and silver nanoparticles are prepared by chemical reductants that utilize excess toxic reactants, which need to be removed for biological purposes. We utilized a clean method involving a single synthetic step to prepare metal nanoparticles for evaluating potential effects on angiogenesis modulation. These nanoparticles were prepared by reducing silver nitrate and gold chloride with diaminopyridinyl (DAP)-derivatized heparin (HP) polysaccharides. Both gold and silver nanoparticles reduced with DAPHP exhibited effective inhibition of basic fibroblast growth factor (FGF-2)-induced angiogenesis, with an enhanced anti-angiogenesis efficacy with the conjugation to DAPHP (P<0.01) as compared to glucose conjugation. These results suggest that DAPHP-reduced silver nanoparticles and gold nanoparticles have potential in pathological angiogenesis accelerated disorders such as cancer and inflammatory diseases.

Deformation twinning of a silver nanocrystal under high pressure. Supplementary materials

DOE PAGES

Huang, X. J.; Yang, W. G.; Harder, R.; ...

2015-10-20

Within a high-pressure environment, crystal deformation is controlled by complex processes such as dislocation motion, twinning, and phase transitions, which change materials’ microscopic morphology and alter their properties. Likewise, understanding a crystal’s response to external stress provides a unique opportunity for rational tailoring of its functionalities. It is very challenging to track the strain evolution and physical deformation from a single nanoscale crystal under high-pressure stress. Here, we report an in situ three-dimensional mapping of morphology and strain evolutions in a single-crystal silver nanocube within a high-pressure environment using the Bragg Coherent Diffractive Imaging (CDI) method. We also observed amore » continuous lattice distortion, followed by a deformation twining process at a constant pressure. The ability to visualize stress-introduced deformation of nanocrystals with high spatial resolution and prominent strain sensitivity provides an important route for interpreting and engineering novel properties of nanomaterials.« less

Arsenic: A Review of the Element's Toxicity, Plant Interactions, and Potential Methods of Remediation.

PubMed

Hettick, Bryan E; Cañas-Carrell, Jaclyn E; French, Amanda D; Klein, David M

2015-08-19

Arsenic is a naturally occurring element with a long history of toxicity. Sites of contamination are found worldwide as a result of both natural processes and anthropogenic activities. The broad scope of arsenic toxicity to humans and its unique interaction with the environment have led to extensive research into its physicochemical properties and toxic behavior in biological systems. The purpose of this review is to compile the results of recent studies concerning the metalloid and consider the chemical and physical properties of arsenic in the broad context of human toxicity and phytoremediation. Areas of focus include arsenic's mechanisms of human toxicity, interaction with plant systems, potential methods of remediation, and protocols for the determination of metals in experimentation. This assessment of the literature indicates that controlling contamination of water sources and plants through effective remediation and management is essential to successfully addressing the problems of arsenic toxicity and contamination.

Landau quantization of Dirac fermions in graphene and its multilayers

NASA Astrophysics Data System (ADS)

Yin, Long-Jing; Bai, Ke-Ke; Wang, Wen-Xiao; Li, Si-Yu; Zhang, Yu; He, Lin

2017-08-01

When electrons are confined in a two-dimensional (2D) system, typical quantum-mechanical phenomena such as Landau quantization can be detected. Graphene systems, including the single atomic layer and few-layer stacked crystals, are ideal 2D materials for studying a variety of quantum-mechanical problems. In this article, we review the experimental progress in the unusual Landau quantized behaviors of Dirac fermions in monolayer and multilayer graphene by using scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS). Through STS measurement of the strong magnetic fields, distinct Landau-level spectra and rich level-splitting phenomena are observed in different graphene layers. These unique properties provide an effective method for identifying the number of layers, as well as the stacking orders, and investigating the fundamentally physical phenomena of graphene. Moreover, in the presence of a strain and charged defects, the Landau quantization of graphene can be significantly modified, leading to unusual spectroscopic and electronic properties.

Compressed glassy carbon: An ultrastrong and elastic interpenetrating graphene network

PubMed Central

Hu, Meng; He, Julong; Zhao, Zhisheng; Strobel, Timothy A.; Hu, Wentao; Yu, Dongli; Sun, Hao; Liu, Lingyu; Li, Zihe; Ma, Mengdong; Kono, Yoshio; Shu, Jinfu; Mao, Ho-kwang; Fei, Yingwei; Shen, Guoyin; Wang, Yanbin; Juhl, Stephen J.; Huang, Jian Yu; Liu, Zhongyuan; Xu, Bo; Tian, Yongjun

2017-01-01

Carbon’s unique ability to have both sp2 and sp3 bonding states gives rise to a range of physical attributes, including excellent mechanical and electrical properties. We show that a series of lightweight, ultrastrong, hard, elastic, and conductive carbons are recovered after compressing sp2-hybridized glassy carbon at various temperatures. Compression induces the local buckling of graphene sheets through sp3 nodes to form interpenetrating graphene networks with long-range disorder and short-range order on the nanometer scale. The compressed glassy carbons have extraordinary specific compressive strengths—more than two times that of commonly used ceramics—and simultaneously exhibit robust elastic recovery in response to local deformations. This type of carbon is an optimal ultralight, ultrastrong material for a wide range of multifunctional applications, and the synthesis methodology demonstrates potential to access entirely new metastable materials with exceptional properties. PMID:28630918

Complex technology of vacuum-arc processing of structural material surface

NASA Astrophysics Data System (ADS)

Arustamov, V. N.; Ashurov, Kh. B.; Kadyrov, Kh. Kh.; Khudoikulov, I. Kh.

2015-08-01

The development of environmentally friendly and energy-resource-saving technologies based on vacuum arc discharge is a topical problem in science and engineering. In view of their unique properties, cathode spots of a vacuum arc induce cleaning of the surface of an article (cathode) from various contaminations and pulsed thermal action on the surface layers. These processes occur in complex with vacuum-arc deposition of coatings in the same technological cycle, which makes it possible to considerably increase the efficiency of methods for changing physical, mechanical, and chemical properties of the surface of steel articles, which considerably increase their service life. Analysis of the formation of the temperature regime of the surface during vacuum arc action and of the parameters of the deposited coating will make it possible to optimize the regimes of complex treatment of the surfaces of articles and is of considerable theoretical and practical importance.

Comparison of the properties of some synthetic crudes with petroleum crudes

NASA Technical Reports Server (NTRS)

Antoine, A. C.

1979-01-01

Physical properties and chemical compositions of six synthetic crudes were determined. The results were compared to those of typical petroleum crudes, with the interest being the feasibility of making jet fuels from oil shale and coal syncrudes. The specific gravity, viscosity, and pour point were measured, showing that these crudes would be described as heavier rather than lighter crudes. The boiling range distribution of the crudes was determined by distillation and by gas chromatography. In addition, gel permeation chromatograms were obtained, giving a unique molecular weight distribution profile for each crude. Analyses for carbon, hydrogen, nitrogen and sulfur concentrations were performed, as well as for hydrocarbon group type and trace element concentrations. It was found that the range in concentration of vanadium, an element whose presence in turbine fuels is of major concern, was lower than that of petroleum crudes. Sodium and potassium, other elements of concern, were present in comparatively high concentrations.

Hierarchical chirality transfer in the growth of Towel Gourd tendrils

PubMed Central

Wang, Jian-Shan; Wang, Gang; Feng, Xi-Qiao; Kitamura, Takayuki; Kang, Yi-Lan; Yu, Shou-Wen; Qin, Qing-Hua

2013-01-01

Chirality plays a significant role in the physical properties and biological functions of many biological materials, e.g., climbing tendrils and twisted leaves, which exhibit chiral growth. However, the mechanisms underlying the chiral growth of biological materials remain unclear. In this paper, we investigate how the Towel Gourd tendrils achieve their chiral growth. Our experiments reveal that the tendrils have a hierarchy of chirality, which transfers from the lower levels to the higher. The change in the helical angle of cellulose fibrils at the subcellular level induces an intrinsic torsion of tendrils, leading to the formation of the helical morphology of tendril filaments. A chirality transfer model is presented to elucidate the chiral growth of tendrils. This present study may help understand various chiral phenomena observed in biological materials. It also suggests that chirality transfer can be utilized in the development of hierarchically chiral materials having unique properties. PMID:24173107

Self-organized molecular films with long-range quasiperiodic order.

PubMed

Fournée, Vincent; Gaudry, Émilie; Ledieu, Julian; de Weerd, Marie-Cécile; Wu, Dongmei; Lograsso, Thomas

2014-04-22

Self-organized molecular films with long-range quasiperiodic order have been grown by using the complex potential energy landscape of quasicrystalline surfaces as templates. The long-range order arises from a specific subset of quasilattice sites acting as preferred adsorption sites for the molecules, thus enforcing a quasiperiodic structure in the film. These adsorption sites exhibit a local 5-fold symmetry resulting from the cut by the surface plane through the cluster units identified in the bulk solid. Symmetry matching between the C60 fullerene and the substrate leads to a preferred adsorption configuration of the molecules with a pentagonal face down, a feature unique to quasicrystalline surfaces, enabling efficient chemical bonding at the molecule-substrate interface. This finding offers opportunities to investigate the physical properties of model 2D quasiperiodic systems, as the molecules can be functionalized to yield architectures with tailor-made properties.

Biogenic formation of photoactive arsenic-sulfide nanotubes by Shewanella sp. strain HN-41

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

Lee, Ji-Hoon; Kim, Min-Gyu; Yoo, Bongyoung

2007-12-18

Microorganisms facilitate the formation of a wide range of minerals that have unique physical and chemical properties as well as morphologies that are not produced by abiotic processes. Here, we report the production of an extensive extracellular network of filamentous, arsenic-sulfide (As-S) nanotubes (20–100 nm in diameter by 30 µm in length) by the dissimilatory metal-reducing bacterium Shewanella sp. HN-41. The As-S nanotubes, formed via the reduction of As(V) and S2O, were initially amorphous As2S3 but evolved with increasing incubation time toward polycrystalline phases of the chalcogenide minerals realgar (AsS) and duranusite (As4S). Upon maturation, the As-S nanotubes behaved asmore » metals and semiconductors in terms of their electrical and photoconductive properties, respectively. The As-S nanotubes produced by Shewanella may provide useful materials for novel nano- and opto-electronic devices.« less

An Active Approach to Colloidal Self-Assembly

NASA Astrophysics Data System (ADS)

Mallory, Stewart A.; Valeriani, Chantal; Cacciuto, Angelo

2018-04-01

In this review, we discuss recent advances in the self-assembly of self-propelled colloidal particles and highlight some of the most exciting results in this field, with a specific focus on dry active matter. We explore this phenomenology through the lens of the complexity of the colloidal building blocks. We begin by considering the behavior of isotropic spherical particles. We then discuss the case of amphiphilic and dipolar Janus particles. Finally, we show how the geometry of the colloids and/or the directionality of their interactions can be used to control the physical properties of the assembled active aggregates, and we suggest possible strategies for how to exploit activity as a tunable driving force for self-assembly. The unique properties of active colloids lend promise to the design of the next generation of functional, environment-sensing microstructures able to perform specific tasks in an autonomous and targeted manner.

Atomically Thin Mesoporous Nanomesh of Graphitic C₃N₄ for High-Efficiency Photocatalytic Hydrogen Evolution.

PubMed

Han, Qing; Wang, Bing; Gao, Jian; Cheng, Zhihua; Zhao, Yang; Zhang, Zhipan; Qu, Liangti

2016-02-23

Delamination of layer materials into two-dimensional single-atom sheets has induced exceptional physical properties, including large surface area, ultrahigh intrinsic carrier mobility, pronounced changes in the energy band structure, and other properties. Here, atomically thin mesoporous nanomesh of graphitic carbon nitride (g-C3N4) is fabricated by solvothermal exfoliation of mesoporous g-C3N4 bulk made from thermal polymerization of freeze-drying assembled Dicyandiamide nanostructure precursor. With the unique structural advantages for aligned energy levels, electron transfer, light harvesting, and the richly available reaction sites, the as-prepared monolayer of mesoporous g-C3N4 nanomesh exhibits a superior photocatalytic hydrogen evolution rate of 8510 μmol h(-1) g(-1) under λ > 420 nm and an apparent quantum efficiency of 5.1% at 420 nm, the highest of all the metal-free g-C3N4 nanosheets photocatalysts.

Biological applications of gold nanoparticles.

PubMed

Shah, Monic; Badwaik, Vivek D; Dakshinamurthy, Rajalingam

2014-01-01

This article reviews some of the recent biological applications of gold nanoparticles (GNPs) which have been discovered lately by individual studies all around the world. GNPs have emerged as a promising candidates for various biological applications due to their unique physical properties (size and shape dependent), excellent biocompatibility, facile synthesis, ease of bioconjugation, etc. This review starts with a brief introduction about nanotechnology followed by an insight into the history, emergence, and enhanced properties of various gold nanostructures, which form the basis for their numerous biomedical applications. In addition, a brief overview on some of the commonly used fabrication techniques for synthesizing GNPs is also discussed. Finally, a miscellany of the latest biological applications of GNPs, such as cancer diagnostics and therapy, biological probes, drug delivery, gene delivery, vaccine preparation, brain implants, artificial skin, sterilization system, and improving electrical signaling in the heart, published in different articles in reputed journals are highlighted.

Free-fermion descriptions of parafermion chains and string-net models

NASA Astrophysics Data System (ADS)

Meichanetzidis, Konstantinos; Turner, Christopher J.; Farjami, Ashk; Papić, Zlatko; Pachos, Jiannis K.

2018-03-01

Topological phases of matter remain a focus of interest due to their unique properties: fractionalization, ground-state degeneracy, and exotic excitations. While some of these properties can occur in systems of free fermions, their emergence is generally associated with interactions between particles. Here, we quantify the role of interactions in general classes of topological states of matter in one and two spatial dimensions, including parafermion chains and string-net models. Surprisingly, we find that certain topological states can be exactly described by free fermions, while others saturate the maximum possible distance from their optimal free-fermion description [C. J. Turner et al., Nat. Commun. 8, 14926 (2017), 10.1038/ncomms14926]. Our work opens the door to understanding the complexity of topological models by establishing new types of fermionization procedures to describe their low-energy physics, thus making them amenable to experimental realizations.

The mechanical behavior of nanoscale metallic multilayers: A survey

NASA Astrophysics Data System (ADS)

Zhou, Q.; Xie, J. Y.; Wang, F.; Huang, P.; Xu, K. W.; Lu, T. J.

2015-06-01

The mechanical behavior of nanoscale metallic multilayers (NMMs) has attracted much attention from both scientific and practical views. Compared with their monolithic counterparts, the large number of interfaces existing in the NMMs dictates the unique behavior of this special class of structural composite materials. While there have been a number of reviews on the mechanical mechanism of microlaminates, the rapid development of nanotechnology brought a pressing need for an overview focusing exclusively on a property-based definition of the NMMs, especially their size-dependent microstructure and mechanical performance. This article attempts to provide a comprehensive and up-to-date review on the microstructure, mechanical property and plastic deformation physics of NMMs. We hope this review could accomplish two purposes: (1) introducing the basic concepts of scaling and dimensional analysis to scientists and engineers working on NMM systems, and (2) providing a better understanding of interface behavior and the exceptional qualities the interfaces in NMMs display at atomic scale.