Sexual Role and Transmission of HIV Type 1 among Men Who Have Sex with Men, in Peru

PubMed Central

Goodreau, Steven M.; Goicochea, L. Pedro; Sanchez, Jorge

2014-01-01

In Latin America, men who have sex with men (MSM) have traditionally practiced role segregation—that is, the adoption of a fixed role (insertive or receptive) rather than a versatile role (both practices) during anal sex. Previous modeling has shown that role segregation may yield a lower incidence of human immunodeficiency virus (HIV) type 1 infection, compared with role versatility; however, the modeling assumed no risk of acquiring HIV-1 during insertive sex, which is now recognized as unlikely. We reexamine the issue by use of a deterministic model incorporating bidirectional transmission and data from a cohort study of MSM in Lima, Peru, to demonstrate the potential effects of role segregation on the trajectory of the HIV-1 epidemic. In Lima, 67% of MSM reported segregated roles in their recent male partnerships. A population of MSM with identical contact rates but complete role versatility would have twice the prevalence of HIV-1 infection throughout the epidemic’s first 3 decades. Preferential mixing among versatile MSM does not change overall prevalence but affects which individuals become infected. PMID:15627225

Directed evolution of new and improved enzyme functions using an evolutionary intermediate and multidirectional search.

PubMed

Porter, Joanne L; Boon, Priscilla L S; Murray, Tracy P; Huber, Thomas; Collyer, Charles A; Ollis, David L

2015-02-20

The ease with which enzymes can be adapted from their native roles and engineered to function specifically for industrial or commercial applications is crucial to enabling enzyme technology to advance beyond its current state. Directed evolution is a powerful tool for engineering enzymes with improved physical and catalytic properties and can be used to evolve enzymes where lack of structural information may thwart the use of rational design. In this study, we take the versatile and diverse α/β hydrolase fold framework, in the form of dienelactone hydrolase, and evolve it over three unique sequential evolutions with a total of 14 rounds of screening to generate a series of enzyme variants. The native enzyme has a low level of promiscuous activity toward p-nitrophenyl acetate but almost undetectable activity toward larger p-nitrophenyl esters. Using p-nitrophenyl acetate as an evolutionary intermediate, we have generated variants with altered specificity and catalytic activity up to 3 orders of magnitude higher than the native enzyme toward the larger nonphysiological p-nitrophenyl ester substrates. Several variants also possess increased stability resulting from the multidimensional approach to screening. Crystal structure analysis and substrate docking show how the enzyme active site changes over the course of the evolutions as either a direct or an indirect result of mutations.

An update on the LIM and SH3 domain protein 1 (LASP1): a versatile structural, signaling, and biomarker protein

PubMed Central

Orth, Martin F.; Cazes, Alex; Butt, Elke; Grunewald, Thomas G. P.

2015-01-01

The gene encoding the LIM and SH3 domain protein (LASP1) was cloned two decades ago from a cDNA library of breast cancer metastases. As the first protein of a class comprising one N-terminal LIM and one C-terminal SH3 domain, LASP1 founded a new LIM-protein subfamily of the nebulin group. Since its discovery LASP1 proved to be an extremely versatile protein because of its exceptional structure allowing interaction with various binding partners, its ubiquitous expression in normal tissues, albeit with distinct expression patterns, and its ability to transmit signals from the cytoplasm into the nucleus. As a result, LASP1 plays key roles in cell structure, physiological processes, and cell signaling. Furthermore, LASP1 overexpression contributes to cancer aggressiveness hinting to a potential value of LASP1 as a cancer biomarker. In this review we summarize published data on structure, regulation, function, and expression pattern of LASP1, with a focus on its role in human cancer and as a biomarker protein. In addition, we provide a comprehensive transcriptome analysis of published microarrays (n=2,780) that illustrates the expression profile of LASP1 in normal tissues and its overexpression in a broad range of human cancer entities. PMID:25622104

Benzomorphan skeleton, a versatile scaffold for different targets: A comprehensive review.

PubMed

Turnaturi, Rita; Montenegro, Lucia; Marrazzo, Agostino; Parenti, Rosalba; Pasquinucci, Lorella; Parenti, Carmela

2018-06-07

Despite the fact that the benzomorphan skeleton has mainly been employed in medicinal chemistry for the development of opioid analgesics, it is a versatile structure. Its stereochemistry, as well as opportune modifications at the phenolic hydroxyl group and at the basic nitrogen, play a pivotal role addressing the benzomorphan-based compounds to a specific target. In this review, we describe the structure activity-relationships (SARs) of benzomorphan-based compounds acting at sigma 1 receptor (σ1R), sigma 2 receptor (σ2R), voltage-dependent sodium channel, N-Methyl-d-Aspartate (NMDA) receptor-channel complex and other targets. Collectively, the SARs data have highlighted that the benzomorphan nucleus could be regarded as a useful template for the synthesis of drug candidates for different targets. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

The PAKs come of age

PubMed Central

2012-01-01

Protein kinases are versatile signaling molecules that are involved in the regulation most physiological responses. The p21-activated kinases (PAKs) can be activated directly by the small GTPases Rac and Cdc42 and are among the best characterized downstream effectors of these Rho proteins. The structure, substrate specificity and functional role of PAKS are evolutionarily conserved from protozoa to mammals. Vertebrate PAKs are particularly important for cytoskeletal remodeling and focal adhesion assembly, thereby contributing to dynamic processes such as cell migration and synaptic plasticity. This issue of Cellular Logistics focuses on the PAK family of kinases, with ten reviews written by researchers currently working in the field. Here in this introductory overview we highlight some of the most interesting recent discoveries regarding PAK biochemistry and biology. The reviews in this issue cover a range of topics including the atomic structures of PAK1 and PAK4, their role in animals as assessed by knockout studies, and how PAKs are likely to contribute to cancer and neurodegenerative diseases. The promise remains that PAK inhibitors will emerge that validate current pre-clinical studies suggesting that blocking PAK activity will positively contribute to human health. PMID:23125949

Resistive pulse sensing of magnetic beads and supraparticle structures using tunable pores

PubMed Central

Willmott, Geoff R.; Platt, Mark; Lee, Gil U.

2012-01-01

Tunable pores (TPs) have been used for resistive pulse sensing of 1 μm superparamagnetic beads, both dispersed and within a magnetic field. Upon application of this field, magnetic supraparticle structures (SPSs) were observed. Onset of aggregation was most effectively indicated by an increase in the mean event magnitude, with data collected using an automated thresholding method. Simulations enabled discrimination between resistive pulses caused by dimers and individual particles. Distinct but time-correlated peaks were often observed, suggesting that SPSs became separated in pressure-driven flow focused at the pore constriction. The distinct properties of magnetophoretic and pressure-driven transport mechanisms can explain variations in the event rate when particles move through an asymmetric pore in either direction, with or without a magnetic field applied. Use of TPs for resistive pulse sensing holds potential for efficient, versatile analysis and measurement of nano- and microparticles, while magnetic beads and particle aggregation play important roles in many prospective biosensing applications. PMID:22662090

Chemistry and Biological Activities of Flavonoids: An Overview

PubMed Central

Kumar, Shashank; Pandey, Abhay K.

2013-01-01

There has been increasing interest in the research on flavonoids from plant sources because of their versatile health benefits reported in various epidemiological studies. Since flavonoids are directly associated with human dietary ingredients and health, there is need to evaluate structure and function relationship. The bioavailability, metabolism, and biological activity of flavonoids depend upon the configuration, total number of hydroxyl groups, and substitution of functional groups about their nuclear structure. Fruits and vegetables are the main dietary sources of flavonoids for humans, along with tea and wine. Most recent researches have focused on the health aspects of flavonoids for humans. Many flavonoids are shown to have antioxidative activity, free radical scavenging capacity, coronary heart disease prevention, hepatoprotective, anti-inflammatory, and anticancer activities, while some flavonoids exhibit potential antiviral activities. In plant systems, flavonoids help in combating oxidative stress and act as growth regulators. For pharmaceutical purposes cost-effective bulk production of different types of flavonoids has been made possible with the help of microbial biotechnology. This review highlights the structural features of flavonoids, their beneficial roles in human health, and significance in plants as well as their microbial production. PMID:24470791

Sidewall patterning—a new wafer-scale method for accurate patterning of vertical silicon structures

NASA Astrophysics Data System (ADS)

Westerik, P. J.; Vijselaar, W. J. C.; Berenschot, J. W.; Tas, N. R.; Huskens, J.; Gardeniers, J. G. E.

2018-01-01

For the definition of wafer scale micro- and nanostructures, in-plane geometry is usually controlled by optical lithography. However, options for precisely patterning structures in the out-of-plane direction are much more limited. In this paper we present a versatile self-aligned technique that allows for reproducible sub-micrometer resolution local modification along vertical silicon sidewalls. Instead of optical lithography, this method makes smart use of inclined ion beam etching to selectively etch the top parts of structures, and controlled retraction of a conformal layer to define a hard mask in the vertical direction. The top, bottom or middle part of a structure could be selectively exposed, and it was shown that these exposed regions can, for example, be selectively covered with a catalyst, doped, or structured further.

Low-Voltage Continuous Electrospinning Patterning.

PubMed

Li, Xia; Li, Zhaoying; Wang, Liyun; Ma, Guokun; Meng, Fanlong; Pritchard, Robyn H; Gill, Elisabeth L; Liu, Ye; Huang, Yan Yan Shery

2016-11-30

Electrospinning is a versatile technique for the construction of microfibrous and nanofibrous structures with considerable potential in applications ranging from textile manufacturing to tissue engineering scaffolds. In the simplest form, electrospinning uses a high voltage of tens of thousands volts to draw out ultrafine polymer fibers over a large distance. However, the high voltage limits the flexible combination of material selection, deposition substrate, and control of patterns. Prior studies show that by performing electrospinning with a well-defined "near-field" condition, the operation voltage can be decreased to the kilovolt range, and further enable more precise patterning of fibril structures on a planar surface. In this work, by using solution dependent "initiators", we demonstrate a further lowering of voltage with an ultralow voltage continuous electrospinning patterning (LEP) technique, which reduces the applied voltage threshold to as low as 50 V, simultaneously permitting direct fiber patterning. The versatility of LEP is shown using a wide range of combination of polymer and solvent systems for thermoplastics and biopolymers. Novel functionalities are also incorporated when a low voltage mode is used in place of a high voltage mode, such as direct printing of living bacteria; the construction of suspended single fibers and membrane networks. The LEP technique reported here should open up new avenues in the patterning of bioelements and free-form nano- to microscale fibrous structures.

Organic Rankine cycle - review and research directions in engine applications

NASA Astrophysics Data System (ADS)

Panesar, Angad

2017-11-01

Waste heat to power conversion using Organic Rankine Cycles (ORC) is expected to play an important role in CO2 reductions from diesel engines. Firstly, a review of automotive ORCs is presented focusing on the pure working fluids, thermal architectures and expanders. The discussion includes, but is not limited to: R245fa, ethanol and water as fluids; series, parallel and cascade as architectures; dry saturated, superheated and supercritical as expansion conditions; and scroll, radial turbine and piston as expansion machines. Secondly, research direction in versatile expander and holistic architecture (NOx + CO2) are proposed. Benefits of using the proposed unconventional approaches are quantified using Ricardo Wave and Aspen HYSYS for diesel engine and ORC modelling. Results indicate that, the implementation of versatile piston expander tolerant to two-phase and using cyclopentane can potentially increase the highway drive cycle power by 8%. Furthermore, holistic architecture offering complete utilisation of charge air and exhaust recirculation heat increased the performance noticeably to 5% of engine power at the design point condition.

Digital Alchemy for Materials Design: Colloids and Beyond

NASA Astrophysics Data System (ADS)

van Anders, Greg; Klotsa, Daphne; Karas, Andrew; Dodd, Paul; Glotzer, Sharon

Starting with the early alchemists, a holy grail of science has been to make desired materials by manipulating basic building blocks. Building blocks that show promise for assembling new complex materials can be synthesized at the nanoscale with attributes that would astonish the ancient alchemists in their versatility. However, this versatility means that connecting building-block attributes to bulk structure is both necessary for rationally engineering materials and difficult because building block attributes can be altered in many ways. We show how to exploit the malleability of colloidal nanoparticle ``elements'' to quantitatively link building-block attributes to bulk structure through a statistical thermodynamic framework we term ``digital alchemy''. We use this framework to optimize building blocks for a given target structure and to determine which building-block attributes are most important to control for self-assembly, through a set of novel thermodynamic response functions. We thereby establish direct links between the attributes of colloidal building blocks and the bulk structures they form. Moreover, our results give concrete solutions to the more general conceptual challenge of optimizing emergent behaviors in nature and can be applied to other types of matter.

Direct Enantioselective Conjugate Addition of Carboxylic Acids with Chiral Lithium Amides as Traceless Auxiliaries

PubMed Central

2016-01-01

Michael addition is a premier synthetic method for carbon–carbon and carbon–heteroatom bond formation. Using chiral dilithium amides as traceless auxiliaries, we report the direct enantioselective Michael addition of carboxylic acids. A free carboxyl group in the product provides versatility for further functionalization, and the chiral reagent can be readily recovered by extraction with aqueous acid. The method has been applied in the enantioselective total synthesis of the purported structure of pulveraven B. PMID:25562717

Direct enantioselective conjugate addition of carboxylic acids with chiral lithium amides as traceless auxiliaries.

PubMed

Lu, Ping; Jackson, Jeffrey J; Eickhoff, John A; Zakarian, Armen

2015-01-21

Michael addition is a premier synthetic method for carbon-carbon and carbon-heteroatom bond formation. Using chiral dilithium amides as traceless auxiliaries, we report the direct enantioselective Michael addition of carboxylic acids. A free carboxyl group in the product provides versatility for further functionalization, and the chiral reagent can be readily recovered by extraction with aqueous acid. The method has been applied in the enantioselective total synthesis of the purported structure of pulveraven B.

Photoelectron diffraction and holography: Some new directions

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

Fadley, C.S.

1993-08-01

Photoelectron diffraction has by now become a versatile and powerful technique for studying surface structures, with special capabilities for resolving chemical and magnetic states of atoms and deriving direct structural information from both forward scattering along bond directions and back-scattering path length differences. Further fitting experiment to theory can lead to structural accuracies in the {plus_minus}0.03 ){Angstrom} range. Holographic inversions of such diffraction data also show considerable promise for deriving local three-dimensional structures around a given emitter with accuracies of {plus_minus}0.2--0.3 {Angstrom}. Resolving the photoelectron spin in some way and using circularly polarized radiation for excitation provide added dimensions formore » the study of magnetic systems and chiral experimental geometries. Synchrotron radiation with the highest brightness and energy resolution, as well as variable polarization, is crucial to the full exploitation of these techniques.« less

Investigation of α-MnO 2 Tunneled Structures as Model Cation Hosts for Energy Storage

DOE PAGES

Housel, Lisa M.; Wang, Lei; Abraham, Alyson; ...

2018-02-19

Future advances in energy storage systems rely on identification of appropriate target materials and deliberate synthesis of the target materials with control of their physiochemical properties in order to disentangling the contributions of distinct properties to the functional electrochemistry. Furthermore, this goal demands systematic inquiry using model materials that provide the opportunity for significant synthetic versatility and control. Ideally, a material family that enables direct manipulation of characteristics including composition, defects and crystallite size while remaining within the defined structural framework would be necessary. Accomplishing this through direct synthetic methods is desirable to minimize the complicating effects of secondary processing.

Investigation of α-MnO 2 Tunneled Structures as Model Cation Hosts for Energy Storage

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

Housel, Lisa M.; Wang, Lei; Abraham, Alyson

Future advances in energy storage systems rely on identification of appropriate target materials and deliberate synthesis of the target materials with control of their physiochemical properties in order to disentangling the contributions of distinct properties to the functional electrochemistry. Furthermore, this goal demands systematic inquiry using model materials that provide the opportunity for significant synthetic versatility and control. Ideally, a material family that enables direct manipulation of characteristics including composition, defects and crystallite size while remaining within the defined structural framework would be necessary. Accomplishing this through direct synthetic methods is desirable to minimize the complicating effects of secondary processing.

Chemical Methods for the Direct Detection and Labeling of S-Nitrosothiols

PubMed Central

Bechtold, Erika

2012-01-01

Abstract Significance: Posttranslational modification of proteins through phosphorylation, glycosylation, and oxidation adds complexity to the proteome by reversibly altering the structure and function of target proteins in a highly controlled fashion. Recent Advances: The study of reversible cysteine oxidation highlights a role for this oxidative modification in complex signal transduction pathways. Nitric oxide (NO), and its respective metabolites (including reactive nitrogen species), participates in a variety of these cellular redox processes, including the reversible oxidation of cysteine to S-nitrosothiols (RSNOs). RSNOs act as endogenous transporters of NO, but also possess beneficial effects independent of NO-related signaling, which suggests a complex and versatile biological role. In this review, we highlight the importance of RSNOs as a required posttranslational modification and summarize the current methods available for detecting S-nitrosation. Critical Issues: Given the limitations of these indirect detection methods, the review covers recent developments toward the direct detection of RSNOs by phosphine-based chemical probes. The intrinsic properties that dictate this phosphine/RSNO reactivity are summarized. In general, RSNOs (both small molecule and protein) react with phosphines to yield reactive S-substituted aza-ylides that undergo further reactions leading to stable RSNO-based adducts. Future Directions: This newly explored chemical reactivity forms the basis of a number of exciting potential chemical methods for protein RSNO detection in biological systems. Antioxid. Redox Signal. 17, 981–991. PMID:22356122

Resolving complex chromosome structures during meiosis: versatile deployment of Smc5/6.

PubMed

Verver, Dideke E; Hwang, Grace H; Jordan, Philip W; Hamer, Geert

2016-03-01

The Smc5/6 complex, along with cohesin and condensin, is a member of the structural maintenance of chromosome (SMC) family, large ring-like protein complexes that are essential for chromatin structure and function. Thanks to numerous studies of the mitotic cell cycle, Smc5/6 has been implicated to have roles in homologous recombination, restart of stalled replication forks, maintenance of ribosomal DNA (rDNA) and heterochromatin, telomerase-independent telomere elongation, and regulation of chromosome topology. The nature of these functions implies that the Smc5/6 complex also contributes to the profound chromatin changes, including meiotic recombination, that characterize meiosis. Only recently, studies in diverse model organisms have focused on the potential meiotic roles of the Smc5/6 complex. Indeed, Smc5/6 appears to be essential for meiotic recombination. However, due to both the complexity of the process of meiosis and the versatility of the Smc5/6 complex, many additional meiotic functions have been described. In this review, we provide a clear overview of the multiple functions found so far for the Smc5/6 complex in meiosis. Additionally, we compare these meiotic functions with the known mitotic functions in an attempt to find a common denominator and thereby create clarity in the field of Smc5/6 research.

Hybrid metal–organic chalcogenide nanowires with electrically conductive inorganic core through diamondoid-directed assembly

DOE PAGES

Yan, Hao; Hohman, J. Nathan; Li, Fei Hua; ...

2016-12-26

Controlling inorganic structure and dimensionality through structure-directing agents is a versatile approach for new materials synthesis that has been used extensively for metal–organic frameworks and coordination polymers. However, the lack of ‘solid’ inorganic cores requires charge transport through single-atom chains and/or organic groups, limiting their electronic properties. Here, we report that strongly interacting diamondoid structure-directing agents guide the growth of hybrid metal–organic chalcogenide nanowires with solid inorganic cores having three-atom cross-sections, representing the smallest possible nanowires. The strong van der Waals attraction between diamondoids overcomes steric repulsion leading to a cis configuration at the active growth front, enabling face-on additionmore » of precursors for nanowire elongation. These nanowires have band-like electronic properties, low effective carrier masses and three orders-of-magnitude conductivity modulation by hole doping. Furthermore, this discovery highlights a previously unexplored regime of structure-directing agents compared with traditional surfactant, block copolymer or metal–organic framework linkers.« less

Sparse Data Representation: The Role of Redundancy in Data Processing

DTIC Science & Technology

2005-09-13

directions The Error Diffusion Halftoning Algorithm: Some Recent Stability Results and Applications Beyond Halftoning Dr. Chai Wu Thomas J. Watson Research...digital and analog printers use some form of halftoning ; just look at any picture in a newspaper or magazine under a magnifying glass. Error diffusion is...a popular technique for high quality digital halftoning . The purpose of this talk is to illustrate the versatility of error diffusion with

Versatile buffer layer architectures based on Ge1-xSnx alloys

NASA Astrophysics Data System (ADS)

Roucka, R.; Tolle, J.; Cook, C.; Chizmeshya, A. V. G.; Kouvetakis, J.; D'Costa, V.; Menendez, J.; Chen, Zhihao D.; Zollner, S.

2005-05-01

We describe methodologies for integration of compound semiconductors with Si via buffer layers and templates based on the GeSn system. These layers exhibit atomically flat surface morphologies, low defect densities, tunable thermal expansion coefficients, and unique ductile properties, which enable them to readily absorb differential stresses produced by mismatched overlayers. They also provide a continuous selection of lattice parameters higher than that of Ge, which allows lattice matching with technologically useful III-V compounds. Using this approach we have demonstrated growth of GaAs, GeSiSn, and pure Ge layers at low temperatures on Si(100). These materials display extremely high-quality structural, morphological, and optical properties opening the possibility of versatile integration schemes directly on silicon.

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

Versatile Cellulose-Based Carbon Aerogel for the Removal of Both Cationic and Anionic Metal Contaminants from Water.

PubMed

Alatalo, Sara-Maaria; Pileidis, Filoklis; Mäkilä, Ermei; Sevilla, Marta; Repo, Eveliina; Salonen, Jarno; Sillanpää, Mika; Titirici, Maria-Magdalena

2015-11-25

Hydrothermal carbonization of cellulose in the presence of the globular protein ovalbumin leads to the formation of nitrogen-doped carbon aerogel with a fibrillar continuous carbon network. The protein plays here a double role: (i) a natural source of nitrogen functionalities (2.1 wt %) and (ii) structural directing agent (S(BET) = 38 m(2)/g). The applicability in wastewater treatment, namely, for heavy metal removal, was examined through adsorption of Cr(VI) and Pb(II) ion solely and in a mixed bicomponent aqueous solutions. This cellulose-based carbogel shows an enhanced ability to remove both Cr(VI) (∼68 mg/g) and Pb(II) (∼240 mg/g) from the targeted solutions in comparison to other carbon materials reported in the literature. The presence of competing ions showed little effect on the adsorption efficiency toward Cr(VI) and Pb(II).

Macro-SICM: A Scanning Ion Conductance Microscope for Large-Range Imaging.

PubMed

Schierbaum, Nicolas; Hack, Martin; Betz, Oliver; Schäffer, Tilman E

2018-04-17

The scanning ion conductance microscope (SICM) is a versatile, high-resolution imaging technique that uses an electrolyte-filled nanopipet as a probe. Its noncontact imaging principle makes the SICM uniquely suited for the investigation of soft and delicate surface structures in a liquid environment. The SICM has found an ever-increasing number of applications in chemistry, physics, and biology. However, a drawback of conventional SICMs is their relatively small scan range (typically 100 μm × 100 μm in the lateral and 10 μm in the vertical direction). We have developed a Macro-SICM with an exceedingly large scan range of 25 mm × 25 mm in the lateral and 0.25 mm in the vertical direction. We demonstrate the high versatility of the Macro-SICM by imaging at different length scales: from centimeters (fingerprint, coin) to millimeters (bovine tongue tissue, insect wing) to micrometers (cellular extensions). We applied the Macro-SICM to the study of collective cell migration in epithelial wound healing.

The role of nanoscale seed layers on the enhanced performance of niobium doped TiO 2 thin films on glass

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

Nikodemski, Stefan; Dameron, Arrelaine A.; Perkins, John D.

Transparent conducting oxide (TCO) coatings with decreased cost and greater process or performance versatility are needed for a variety of optoelectronic applications. Among potential new TCO candidates, doped titanium dioxide is receiving particular interest. In this study, niobium-doped titania bilayer structures consisting of a nanoscale seed layer (deposited by atomic layer deposition or RF magnetron sputtering) followed by a thick bulk-like layer were grown directly on glass in order to examine the effects of the seed layer processing on the subsequent crystallization and electrical properties of these heterostructures. Observations from Raman spectroscopy suggest that higher oxygen content in the seedmore » layer suppresses the formation of detrimental titania polymorph phases, found in films produced by annealing directly after synthesis without any exposure to oxygen. Here, our results indicate that the generation of excellent Nb:TiO 2 conductors on glass (without breaking vacuum) only occurs within a narrow processing range and that the sequential deposition of oxygen-poor layers on oxygen-rich layers is a critical step towards achieving films with low resistivity.« less

The role of nanoscale seed layers on the enhanced performance of niobium doped TiO 2 thin films on glass

DOE PAGES

Nikodemski, Stefan; Dameron, Arrelaine A.; Perkins, John D.; ...

2016-09-09

Transparent conducting oxide (TCO) coatings with decreased cost and greater process or performance versatility are needed for a variety of optoelectronic applications. Among potential new TCO candidates, doped titanium dioxide is receiving particular interest. In this study, niobium-doped titania bilayer structures consisting of a nanoscale seed layer (deposited by atomic layer deposition or RF magnetron sputtering) followed by a thick bulk-like layer were grown directly on glass in order to examine the effects of the seed layer processing on the subsequent crystallization and electrical properties of these heterostructures. Observations from Raman spectroscopy suggest that higher oxygen content in the seedmore » layer suppresses the formation of detrimental titania polymorph phases, found in films produced by annealing directly after synthesis without any exposure to oxygen. Here, our results indicate that the generation of excellent Nb:TiO 2 conductors on glass (without breaking vacuum) only occurs within a narrow processing range and that the sequential deposition of oxygen-poor layers on oxygen-rich layers is a critical step towards achieving films with low resistivity.« less

Marine Rare Actinobacteria: Isolation, Characterization, and Strategies for Harnessing Bioactive Compounds

PubMed Central

Dhakal, Dipesh; Pokhrel, Anaya Raj; Shrestha, Biplav; Sohng, Jae Kyung

2017-01-01

Actinobacteria are prolific producers of thousands of biologically active natural compounds with diverse activities. More than half of these bioactive compounds have been isolated from members belonging to actinobacteria. Recently, rare actinobacteria existing at different environmental settings such as high altitudes, volcanic areas, and marine environment have attracted attention. It has been speculated that physiological or biochemical pressures under such harsh environmental conditions can lead to the production of diversified natural compounds. Hence, marine environment has been focused for the discovery of novel natural products with biological potency. Many novel and promising bioactive compounds with versatile medicinal, industrial, or agricultural uses have been isolated and characterized. The natural compounds cannot be directly used as drug or other purposes, so they are structurally modified and diversified to ameliorate their biological or chemical properties. Versatile synthetic biological tools, metabolic engineering techniques, and chemical synthesis platform can be used to assist such structural modification. This review summarizes the latest studies on marine rare actinobacteria and their natural products with focus on recent approaches for structural and functional diversification of such microbial chemicals for attaining better applications. PMID:28663748

Revealing Nanostructures through Plasmon Polarimetry.

PubMed

Kleemann, Marie-Elena; Mertens, Jan; Zheng, Xuezhi; Cormier, Sean; Turek, Vladimir; Benz, Felix; Chikkaraddy, Rohit; Deacon, William; Lombardi, Anna; Moshchalkov, Victor V; Vandenbosch, Guy A E; Baumberg, Jeremy J

2017-01-24

Polarized optical dark-field spectroscopy is shown to be a versatile noninvasive probe of plasmonic structures that trap light to the nanoscale. Clear spectral polarization splittings are found to be directly related to the asymmetric morphology of nanocavities formed between faceted gold nanoparticles and an underlying gold substrate. Both experiment and simulation show the influence of geometry on the coupled system, with spectral shifts Δλ = 3 nm from single atoms. Analytical models allow us to identify the split resonances as transverse cavity modes, tightly confined to the nanogap. The direct correlation of resonance splitting with atomistic morphology allows mapping of subnanometre structures, which is crucial for progress in extreme nano-optics involving chemistry, nanophotonics, and quantum devices.

Using the NASTRAN Thermal Analyzer to simulate a flight scientific instrument package

NASA Technical Reports Server (NTRS)

Lee, H.-P.; Jackson, C. E., Jr.

1974-01-01

The NASTRAN Thermal Analyzer has proven to be a unique and useful tool for thermal analyses involving large and complex structures where small, thermally induced deformations are critical. Among its major advantages are direct grid point-to-grid point compatibility with large structural models; plots of the model that may be generated for both conduction and boundary elements; versatility of applying transient thermal loads especially to repeat orbital cycles; on-line printer plotting of temperatures and rate of temperature changes as a function of time; and direct matrix input to solve linear differential equations on-line. These features provide a flexibility far beyond that available in most finite-difference thermal analysis computer programs.

Neural network based chemical structure indexing.

PubMed

Rughooputh, S D; Rughooputh, H C

2001-01-01

Searches on chemical databases are presently dominated by the text-based content of a paper which can be indexed into a keyword searchable form. Such traditional searches can prove to be very time-consuming and discouraging to the less frequent scientist. We report a simple chemical indexing based on the molecular structure alone. The method used is based on a one-to-one correspondence between the chemical structure presented as an image to a neural network and the corresponding binary output. The method is direct and less cumbersome (compared with traditional methods) and proves to be robust, elegant, and very versatile.

Directed assembly of gold nanowires on silicon via reorganization and simultaneous fusion of randomly distributed gold nanoparticles.

PubMed

Reinhardt, Hendrik M; Bücker, Kerstin; Hampp, Norbert A

2015-05-04

Laser-induced reorganization and simultaneous fusion of nanoparticles is introduced as a versatile concept for pattern formation on surfaces. The process takes advantage of a phenomenon called laser-induced periodic surface structures (LIPSS) which originates from periodically alternating photonic fringe patterns in the near-field of solids. Associated photonic fringe patterns are shown to reorganize randomly distributed gold nanoparticles on a silicon wafer into periodic gold nanostructures. Concomitant melting due to optical heating facilitates the formation of continuous structures such as periodic gold nanowire arrays. Generated patterns can be converted into secondary structures using directed assembly or self-organization. This includes for example the rotation of gold nanowire arrays by arbitrary angles or their fragmentation into arrays of aligned gold nanoparticles.

Structure-based Engineering of a Plant-Fungal Hybrid Peroxidase for Enhanced Temperature and pH Tolerance.

PubMed

Kohler, Amanda C; Simmons, Blake A; Sale, Kenneth L

2018-04-28

In an age of ever-increasing biotechnological and industrial demand for new and specialized biocatalysts, rational protein engineering offers a direct approach to enzyme design and innovation. Heme peroxidases, as indispensable oxidative biocatalysts, provide a relatively mild alternative to the traditional harsh, and often toxic, chemical catalysts, and subsequently, have found widespread application throughout industry. However, the potential for these enzymes is far greater than their present use, as processes are currently restricted to the more stable, but less catalytically powerful, subset of peroxidases. Here we describe the structure-guided, rational engineering of a plant-fungal hybrid peroxidase built to overcome the application barrier of these high-reduction potential peroxidases. This engineered enzyme has the catalytic versatility and oxidative ability of a high-reduction potential versatile peroxidase, with enhanced temperature and pH tolerance similar to that of a highly stable plant peroxidase. Copyright © 2018 Elsevier Ltd. All rights reserved.

Re-engineering of Bacterial Luciferase; For New Aspects of Bioluminescence.

PubMed

Kim, Da-Som; Choi, Jeong-Ran; Ko, Jeong-Ae; Kim, Kangmin

2018-01-01

Bacterial luminescence is the end-product of biochemical reactions catalyzed by the luciferase enzyme. Nowadays, this fascinating phenomenon has been widely used as reporter and/or sensors to detect a variety of biological and environmental processes. The enhancement or diversification of the luciferase activities will increase the versatility of bacterial luminescence. Here, to establish the strategy for luciferase engineering, we summarized the identity and relevant roles of key amino acid residues modulating luciferase in Vibrio harveyi, a model luminous bacterium. The current opinions on crystal structures and the critical amino acid residues involved in the substrate binding sites and unstructured loop have been delineated. Based on these, the potential target residues and/or parameters for enzyme engineering were also suggested in limited scale. In conclusion, even though the accurate knowledge on the bacterial luciferase is yet to be reported, the structure-guided site-directed mutagenesis approaches targeting the regulatory amino acids will provide a useful platform to re-engineer the bacterial luciferase in the future. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Protein intrinsic disorder in plants.

PubMed

Pazos, Florencio; Pietrosemoli, Natalia; García-Martín, Juan A; Solano, Roberto

2013-09-12

To some extent contradicting the classical paradigm of the relationship between protein 3D structure and function, now it is clear that large portions of the proteomes, especially in higher organisms, lack a fixed structure and still perform very important functions. Proteins completely or partially unstructured in their native (functional) form are involved in key cellular processes underlain by complex networks of protein interactions. The intrinsic conformational flexibility of these disordered proteins allows them to bind multiple partners in transient interactions of high specificity and low affinity. In concordance, in plants this type of proteins has been found in processes requiring these complex and versatile interaction networks. These include transcription factor networks, where disordered proteins act as integrators of different signals or link different transcription factor subnetworks due to their ability to interact (in many cases simultaneously) with different partners. Similarly, they also serve as signal integrators in signaling cascades, such as those related to response to external stimuli. Disordered proteins have also been found in plants in many stress-response processes, acting as protein chaperones or protecting other cellular components and structures. In plants, it is especially important to have complex and versatile networks able to quickly and efficiently respond to changing environmental conditions since these organisms cannot escape and have no other choice than adapting to them. Consequently, protein disorder can play an especially important role in plants, providing them with a fast mechanism to obtain complex, interconnected and versatile molecular networks.

Protein intrinsic disorder in plants

PubMed Central

Pazos, Florencio; Pietrosemoli, Natalia; García-Martín, Juan A.; Solano, Roberto

2013-01-01

To some extent contradicting the classical paradigm of the relationship between protein 3D structure and function, now it is clear that large portions of the proteomes, especially in higher organisms, lack a fixed structure and still perform very important functions. Proteins completely or partially unstructured in their native (functional) form are involved in key cellular processes underlain by complex networks of protein interactions. The intrinsic conformational flexibility of these disordered proteins allows them to bind multiple partners in transient interactions of high specificity and low affinity. In concordance, in plants this type of proteins has been found in processes requiring these complex and versatile interaction networks. These include transcription factor networks, where disordered proteins act as integrators of different signals or link different transcription factor subnetworks due to their ability to interact (in many cases simultaneously) with different partners. Similarly, they also serve as signal integrators in signaling cascades, such as those related to response to external stimuli. Disordered proteins have also been found in plants in many stress-response processes, acting as protein chaperones or protecting other cellular components and structures. In plants, it is especially important to have complex and versatile networks able to quickly and efficiently respond to changing environmental conditions since these organisms cannot escape and have no other choice than adapting to them. Consequently, protein disorder can play an especially important role in plants, providing them with a fast mechanism to obtain complex, interconnected and versatile molecular networks. PMID:24062761

The Crystal Structure of Cancer Osaka Thyroid Kinase Reveals an Unexpected Kinase Domain Fold*

PubMed Central

Gutmann, Sascha; Hinniger, Alexandra; Fendrich, Gabriele; Drückes, Peter; Antz, Sylvie; Mattes, Henri; Möbitz, Henrik; Ofner, Silvio; Schmiedeberg, Niko; Stojanovic, Aleksandar; Rieffel, Sebastien; Strauss, André; Troxler, Thomas; Glatthar, Ralf; Sparrer, Helmut

2015-01-01

Macrophages are important cellular effectors in innate immune responses and play a major role in autoimmune diseases such as rheumatoid arthritis. Cancer Osaka thyroid (COT) kinase, also known as mitogen-activated protein kinase kinase kinase 8 (MAP3K8) and tumor progression locus 2 (Tpl-2), is a serine-threonine (ST) kinase and is a key regulator in the production of pro-inflammatory cytokines in macrophages. Due to its pivotal role in immune biology, COT kinase has been identified as an attractive target for pharmaceutical research that is directed at the discovery of orally available, selective, and potent inhibitors for the treatment of autoimmune disorders and cancer. The production of monomeric, recombinant COT kinase has proven to be very difficult, and issues with solubility and stability of the enzyme have hampered the discovery and optimization of potent and selective inhibitors. We developed a protocol for the production of recombinant human COT kinase that yields pure and highly active enzyme in sufficient yields for biochemical and structural studies. The quality of the enzyme allowed us to establish a robust in vitro phosphorylation assay for the efficient biochemical characterization of COT kinase inhibitors and to determine the x-ray co-crystal structures of the COT kinase domain in complex with two ATP-binding site inhibitors. The structures presented in this study reveal two distinct ligand binding modes and a unique kinase domain architecture that has not been observed previously. The structurally versatile active site significantly impacts the design of potent, low molecular weight COT kinase inhibitors. PMID:25918157

Functional Versatility of AGY Serine Codons in Immunoglobulin Variable Region Genes

PubMed Central

Detanico, Thiago; Phillips, Matthew; Wysocki, Lawrence J.

2016-01-01

In systemic autoimmunity, autoantibodies directed against nuclear antigens (Ags) often arise by somatic hypermutation (SHM) that converts AGT and AGC (AGY) Ser codons into Arg codons. This can occur by three different single-base changes. Curiously, AGY Ser codons are far more abundant in complementarity-determining regions (CDRs) of IgV-region genes than expected for random codon use or from species-specific codon frequency data. CDR AGY codons are also more abundant than TCN Ser codons. We show that these trends hold even in cartilaginous fishes. Because AGC is a preferred target for SHM by activation-induced cytidine deaminase, we asked whether the AGY abundance was solely due to a selection pressure to conserve high mutability in CDRs regardless of codon context but found that this was not the case. Instead, AGY triplets were selectively enriched in the Ser codon reading frame. Motivated by reports implicating a functional role for poly/autoreactive specificities in antiviral antibodies, we also analyzed mutations at AGY in antibodies directed against a number of different viruses and found that mutations producing Arg codons in antiviral antibodies were indeed frequent. Unexpectedly, however, we also found that AGY codons mutated often to encode nearly all of the amino acids that are reported to provide the most frequent contacts with Ag. In many cases, mutations producing codons for these alternative amino acids in antiviral antibodies were more frequent than those producing Arg codons. Mutations producing each of these key amino acids required only single-base changes in AGY. AGY is the only codon group in which two-thirds of random mutations generate codons for these key residues. Finally, by directly analyzing X-ray structures of immune complexes from the RCSB protein database, we found that Ag-contact residues generated via SHM occurred more often at AGY than at any other codon group. Thus, preservation of AGY codons in antibody genes appears to have been driven by their exceptional functional versatility, despite potential autoreactive consequences. PMID:27920779

Structures of minute virus of mice replication initiator protein N-terminal domain: Insights into DNA nicking and origin binding

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

Tewary, Sunil K.; Liang, Lingfei; Lin, Zihan

Members of the Parvoviridae family all encode a non-structural protein 1 (NS1) that directs replication of single-stranded viral DNA, packages viral DNA into capsid, and serves as a potent transcriptional activator. Here we report the X-ray structure of the minute virus of mice (MVM) NS1 N-terminal domain at 1.45 Å resolution, showing that sites for dsDNA binding, ssDNA binding and cleavage, nuclear localization, and other functions are integrated on a canonical fold of the histidine-hydrophobic-histidine superfamily of nucleases, including elements specific for this Protoparvovirus but distinct from its Bocaparvovirus or Dependoparvovirus orthologs. High resolution structural analysis reveals a nickase activemore » site with an architecture that allows highly versatile metal ligand binding. The structures support a unified mechanism of replication origin recognition for homotelomeric and heterotelomeric parvoviruses, mediated by a basic-residue-rich hairpin and an adjacent helix in the initiator proteins and by tandem tetranucleotide motifs in the replication origins. - Highlights: • The structure of a parvovirus replication initiator protein has been determined; • The structure sheds light on mechanisms of ssDNA binding and cleavage; • The nickase active site is preconfigured for versatile metal ligand binding; • The binding site for the double-stranded replication origin DNA is identified; • A single domain integrates multiple functions in virus replication.« less

Phenotypic constraints promote latent versatility and carbon efficiency in metabolic networks.

PubMed

Bardoscia, Marco; Marsili, Matteo; Samal, Areejit

2015-07-01

System-level properties of metabolic networks may be the direct product of natural selection or arise as a by-product of selection on other properties. Here we study the effect of direct selective pressure for growth or viability in particular environments on two properties of metabolic networks: latent versatility to function in additional environments and carbon usage efficiency. Using a Markov chain Monte Carlo (MCMC) sampling based on flux balance analysis (FBA), we sample from a known biochemical universe random viable metabolic networks that differ in the number of directly constrained environments. We find that the latent versatility of sampled metabolic networks increases with the number of directly constrained environments and with the size of the networks. We then show that the average carbon wastage of sampled metabolic networks across the constrained environments decreases with the number of directly constrained environments and with the size of the networks. Our work expands the growing body of evidence about nonadaptive origins of key functional properties of biological networks.

Metal hierarchical patterning by direct nanoimprint lithography

PubMed Central

Radha, Boya; Lim, Su Hui; Saifullah, Mohammad S. M.; Kulkarni, Giridhar U.

2013-01-01

Three-dimensional hierarchical patterning of metals is of paramount importance in diverse fields involving photonics, controlling surface wettability and wearable electronics. Conventionally, this type of structuring is tedious and usually involves layer-by-layer lithographic patterning. Here, we describe a simple process of direct nanoimprint lithography using palladium benzylthiolate, a versatile metal-organic ink, which not only leads to the formation of hierarchical patterns but also is amenable to layer-by-layer stacking of the metal over large areas. The key to achieving such multi-faceted patterning is hysteretic melting of ink, enabling its shaping. It undergoes transformation to metallic palladium under gentle thermal conditions without affecting the integrity of the hierarchical patterns on micro- as well as nanoscale. A metallic rice leaf structure showing anisotropic wetting behavior and woodpile-like structures were thus fabricated. Furthermore, this method is extendable for transferring imprinted structures to a flexible substrate to make them robust enough to sustain numerous bending cycles. PMID:23446801

Elastic liposomes as novel carriers: recent advances in drug delivery

PubMed Central

Hussain, Afzal; Singh, Sima; Sharma, Dinesh; Webster, Thomas J; Shafaat, Kausar; Faruk, Abdul

2017-01-01

Elastic liposomes (EL) are some of the most versatile deformable vesicular carriers that comprise physiologically biocompatible lipids and surfactants for the delivery of numerous challenging molecules and have marked advantages over other colloidal systems. They have been investigated for a wide range of applications in pharmaceutical technology through topical, transdermal, nasal, and oral routes for efficient and effective drug delivery. Increased drug encapsulation efficiency, enhanced drug permeation and penetration into or across the skin, and ultradeformability have led to widespread interest in ELs to modulate drug release, permeation, and drug action more efficiently than conventional drug-release vehicles. This review provides insights into the versatile role that ELs play in the delivery of numerous drugs and biomolecules by improving drug release, permeation, and penetration across the skin as well as stability. Furthermore, it provides future directions that should ensure the widespread use of ELs across all medical fields. PMID:28761343

Elastic liposomes as novel carriers: recent advances in drug delivery.

PubMed

Hussain, Afzal; Singh, Sima; Sharma, Dinesh; Webster, Thomas J; Shafaat, Kausar; Faruk, Abdul

2017-01-01

Elastic liposomes (EL) are some of the most versatile deformable vesicular carriers that comprise physiologically biocompatible lipids and surfactants for the delivery of numerous challenging molecules and have marked advantages over other colloidal systems. They have been investigated for a wide range of applications in pharmaceutical technology through topical, transdermal, nasal, and oral routes for efficient and effective drug delivery. Increased drug encapsulation efficiency, enhanced drug permeation and penetration into or across the skin, and ultradeformability have led to widespread interest in ELs to modulate drug release, permeation, and drug action more efficiently than conventional drug-release vehicles. This review provides insights into the versatile role that ELs play in the delivery of numerous drugs and biomolecules by improving drug release, permeation, and penetration across the skin as well as stability. Furthermore, it provides future directions that should ensure the widespread use of ELs across all medical fields.

The Influence of Physical Body Traits and Masculinity on Anal Sex Roles in Gay and Bisexual Men

PubMed Central

Moskowitz, David A.; Hart, Trevor A.

2016-01-01

Sociological, psychological, and public health studies document that many gay and bisexual men may self-label by their anal penetrative role (i.e., bottom or exclusively receptive; top or exclusively insertive; or versatile, both receptive and insertive during anal intercourse). Yet, what orients men to think of themselves as tops, bottoms or versatiles is poorly understood. We surveyed 429 men engaging in same-sex anal intercourse to investigate the degree to which anal penetrative self-identity was concordant with actual penetrative behavior. Additionally, the roles of masculinity and physical body traits (e.g., penis size, muscularity, height, hairiness, and weight) were tested as correlates of anal penetrative identity and identity-behavior concordance. Tops and bottoms showed a high degree of concordance between identity and enacted behavior; however, only half of versatiles reported concordant identity and behavior (i.e., wanting to be versatile and actually reporting versatile behavior). Generally, tops reported larger penises than bottoms. They also reported being comparatively more masculine than bottoms. Versatiles fell somewhat between the tops and bottoms on these traits. Of the six independent variables, penis size and masculinity were the only two factors to influence concordance or discordance between identity and penetrative behavior. Our study suggests that the correlates of gay men’s sexual self-labels may depend on objective traits in addition to the subjective pleasure associated with receptive or insertive anal intercourse. PMID:21465269

Broadband and flexible acoustic focusing by metafiber bundles

NASA Astrophysics Data System (ADS)

Sun, Hong-Xiang; Chen, Jia-He; Ge, Yong; Yuan, Shou-Qi; Liu, Xiao-Jun

2018-06-01

We report a broadband and flexible acoustic focusing through metafiber bundles in air, in which each metafiber consists of eight circular and narrow rectangular cavities. The fractional bandwidth of the acoustic focusing could reach about 0.2, which arises from the eigenmodes of the metafiber structure. Besides, owing to the flexible characteristic of the metafibers, the focus position can be manipulated by bending the metafiber bundles, and the metafiber bundles could bypass rigid scatterers inside the lens structure. More interestingly, the acoustic propagation and focusing directions can be changed by using a designed right-angled direction converter fabricated by the metafibers, and a waveform converter and a focusing lens of the cylindrical acoustic source are realized based on the metafiber bundles. The proposed focusing lens has the advantages of broad bandwidth, flexible structure, and high focusing performance, showing great potentials in versatile applications.

Direct Femtosecond Laser Surface Structuring with Optical Vortex Beams Generated by a q-plate

PubMed Central

JJ Nivas, Jijil; He, Shutong; Rubano, Andrea; Vecchione, Antonio; Paparo, Domenico; Marrucci, Lorenzo; Bruzzese, Riccardo; Amoruso, Salvatore

2015-01-01

Creation of patterns and structures on surfaces at the micro- and nano-scale is a field of growing interest. Direct femtosecond laser surface structuring with a Gaussian-like beam intensity profile has already distinguished itself as a versatile method to fabricate surface structures on metals and semiconductors. Here we present an approach for direct femtosecond laser surface structuring based on optical vortex beams with different spatial distributions of the state of polarization, which are easily generated by means of a q-plate. The different states of an optical vortex beam carrying an orbital angular momentum ℓ = ±1 are used to demonstrate the fabrication of various regular surface patterns on silicon. The spatial features of the regular rippled and grooved surface structures are correlated with the state of polarization of the optical vortex beam. Moreover, scattered surface wave theory approach is used to rationalize the dependence of the surface structures on the local state of the laser beam characteristics (polarization and fluence). The present approach can be further extended to fabricate even more complex and unconventional surface structures by exploiting the possibilities offered by femtosecond optical vector fields. PMID:26658307

Beta delayed neutrons for nuclear structure and astrophysics

NASA Astrophysics Data System (ADS)

Grzywacz, Robert

2014-09-01

Beta-delayed neutron emission (β xn) is a significant or even dominant decay channel for the majority of very neutron-rich nuclei, especially for those on the r-process path. The recent theoretical models predicts that it may play more significant role then previously expected for astrophysics and this realization instigated a renewed experimental interest in this topic as a part of a larger scope of research on beta-decay strength distribution. Because studies of the decay strength directly probe relevant physics on the microscopic level, energy-resolved measurements of the beta-decay strength distribution is a better test of nuclear models than traditionally used experimental observables like half-lives and neutron branching ratios. A new detector system called the Versatile Array of Neutron Detectors at Low Energy (VANDLE) was constructed to directly address this issue. In its first experimental campaign at the Holifield Radioactive Ion Beam Facility neutron energy spectra in key regions of the nuclear chart were measured: near the shell closures at 78Ni and 132Sn, and for the deformed nuclei near 100Rb. In several cases, unexpectedly intense and concentrated, resonant-like, high-energy neutron structures were observed. These results were interpreted within shell model framework which clearly indicated that these neutron emission is driven by nuclear structure effects and are due to large Gamow-Teller type transition matrix elements. This research was sponsored in part by the National Nuclear Security Administration under the Stewardship Science Academic Alliances program through DOE Cooperative Agreement No. DE-FG52-08NA28552.

Benzyl Alcohol-Mediated Versatile Method to Fabricate Nonstoichiometric Metal Oxide Nanostructures.

PubMed

Qamar, Mohammad; Adam, Alaaldin; Azad, Abdul-Majeed; Kim, Yong-Wah

2017-11-22

Nanostructured metal oxides with cationic or anionic deficiency find applications in a wide range of technological areas including the energy sector and environment. However, a facile route to prepare such materials in bulk with acceptable reproducibility is still lacking; many synthesis techniques are still only bench-top and cannot be easily scaled-up. Here, we report that the benzyl alcohol (BA)-mediated method is capable of producing a host of nanostructured metal oxides (MO x , where M = Ti, Zn, Ce, Sn, In, Ga, or Fe) with inherent nonstoichiometry. It employs multifunctional BA as a solvent, a reducing agent, and a structure-directing agent. Depending on the oxidation states of metal, elemental or nonstoichiometric oxide forms are obtained. Augmented photoelectrochemical oxidation of water under visible light by some of these nonstoichiometric oxides highlights the versatility of the BA-mediated synthesis protocol.

Peptide-mediated vectorization of metal complexes: conjugation strategies and biomedical applications.

PubMed

Soler, Marta; Feliu, Lidia; Planas, Marta; Ribas, Xavi; Costas, Miquel

2016-08-16

The rich chemical and structural versatility of transition metal complexes provides numerous novel paths to be pursued in the design of molecules that exert particular chemical or physicochemical effects that could operate over specific biological targets. However, the poor cell permeability of metallodrugs represents an important barrier for their therapeutic use. The conjugation between metal complexes and a functional peptide vector can be regarded as a versatile and potential strategy to improve their bioavailability and accumulation inside cells, and the site selectivity of their effect. This perspective lies in reviewing the recent advances in the design of metallopeptide conjugates for biomedical applications. Additionally, we highlight the studies where this approach has been directed towards the incorporation of redox active metal centers into living organisms for modulating the cellular redox balance, as a tool with application in anticancer therapy.

Versatile derivatives of carbohydrate-binding modules for imaging of complex carbohydrates approaching the molecular level of resolution.

PubMed

Ding, Shi-You; Xu, Qi; Ali, Mursheda K; Baker, John O; Bayer, Edward A; Barak, Yoav; Lamed, Raphael; Sugiyama, Junji; Rumbles, Garry; Himmel, Michael E

2006-10-01

The innate binding specificity of different carbohydrate-binding modules (CBMs) offers a versatile approach for mapping the chemistry and structure of surfaces that contain complex carbohydrates. We have employed the distinct recognition properties of a double His-tagged recombinant CBM tagged with semiconductor quantum dots for direct imaging of crystalline cellulose at the molecular level of resolution, using transmission and scanning transmission electron microscopy. In addition, three different types of CBMs from families 3, 6, and 20 that exhibit different carbohydrate specificities were each fused with either green fluorescent protein (GFP) or red fluorescent protein (RFP) and employed for double-labeling fluorescence microscopy studies of primary cell walls and various mixtures of complex carbohydrate target molecules. CBM probes can be used for characterizing both native complex carbohydrates and engineered biomaterials.

Highly Adsorptive, MOF-Functionalized Nonwoven Fiber Mats for Hazardous Gas Capture Enabled by Atomic Layer Deposition

DTIC Science & Technology

2014-03-20

ligands, [ 3 ] exhibit high surface area, good thermal stability, and have signifi cant synthetic versatility, ena- bling structures with tunable pore...sizes and adjustable internal functionality. [ 4 ] MOF synthesis usually follows wet solvo- thermal batch methods, producing pow- ders that require...surface areas—limiting applicability. For example, Kuesgens et al. grew HKUST-1 crystals on pulp fibers using direct solvo- thermal synthesis and found

Direct Observation of a Carbon Filament in Water-Resistant Organic Memory.

PubMed

Lee, Byung-Hyun; Bae, Hagyoul; Seong, Hyejeong; Lee, Dong-Il; Park, Hongkeun; Choi, Young Joo; Im, Sung-Gap; Kim, Sang Ouk; Choi, Yang-Kyu

2015-07-28

The memory for the Internet of Things (IoT) requires versatile characteristics such as flexibility, wearability, and stability in outdoor environments. Resistive random access memory (RRAM) to harness a simple structure and organic material with good flexibility can be an attractive candidate for IoT memory. However, its solution-oriented process and unclear switching mechanism are critical problems. Here we demonstrate iCVD polymer-intercalated RRAM (i-RRAM). i-RRAM exhibits robust flexibility and versatile wearability on any substrate. Stable operation of i-RRAM, even in water, is demonstrated, which is the first experimental presentation of water-resistant organic memory without any waterproof protection package. Moreover, the direct observation of a carbon filament is also reported for the first time using transmission electron microscopy, which puts an end to the controversy surrounding the switching mechanism. Therefore, reproducibility is feasible through comprehensive modeling. Furthermore, a carbon filament is superior to a metal filament in terms of the design window and selection of the electrode material. These results suggest an alternative to solve the critical issues of organic RRAM and an optimized memory type suitable for the IoT era.

Self-assembled bionanostructures: proteins following the lead of DNA nanostructures

PubMed Central

2014-01-01

Natural polymers are able to self-assemble into versatile nanostructures based on the information encoded into their primary structure. The structural richness of biopolymer-based nanostructures depends on the information content of building blocks and the available biological machinery to assemble and decode polymers with a defined sequence. Natural polypeptides comprise 20 amino acids with very different properties in comparison to only 4 structurally similar nucleotides, building elements of nucleic acids. Nevertheless the ease of synthesizing polynucleotides with selected sequence and the ability to encode the nanostructural assembly based on the two specific nucleotide pairs underlay the development of techniques to self-assemble almost any selected three-dimensional nanostructure from polynucleotides. Despite more complex design rules, peptides were successfully used to assemble symmetric nanostructures, such as fibrils and spheres. While earlier designed protein-based nanostructures used linked natural oligomerizing domains, recent design of new oligomerizing interaction surfaces and introduction of the platform for topologically designed protein fold may enable polypeptide-based design to follow the track of DNA nanostructures. The advantages of protein-based nanostructures, such as the functional versatility and cost effective and sustainable production methods provide strong incentive for further development in this direction. PMID:24491139

Bridging Zirconia Nodes within a Metal–Organic Framework via Catalytic Ni-Hydroxo Clusters to Form Heterobimetallic Nanowires

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

Platero-Prats, Ana E.; League, Aaron B.; Bernales, Varinia

Metal-organic frameworks (MOFs), with their well-ordered pore networks and tunable surface chemistries, offer a versatile platform for preparing well-defined nanostructures wherein functionality such as catalysis can be incorporated. Notably, atomic layer deposition (ALD) in MOFs has recently emerged as a versatile approach to functionalize MOF surfaces with a wide variety of catalytic metal-oxo species. Understanding the structure of newly deposited species and how they are tethered within the MOF is critical to understanding how these components couple to govern the active material properties. By combining local and long-range structure probes, including X-ray absorption spectroscopy, pair distribution function analysis and differencemore » envelope density analysis, with electron microscopy imag-ing and computational modeling, we resolve the precise atomic structure of metal-oxo species deposited in the MOF NU-1000 through ALD. These analyses demonstrate that deposition of NiO xH y clusters occurs selectively within the smallest pores of NU-1000, between the zirconia nodes, serving to connect these nodes along the c-direction to yield hetero-bimetallic metal-oxo nanowires. Finally, this bridging motif perturbs the NU-1000 framework structure, drawing the zirconia nodes closer together, and also underlies the sintering-resistance of these clusters during the hydrogenation of light olefins.« less

Bridging Zirconia Nodes within a Metal-Organic Framework via Catalytic Ni-Hydroxo Clusters to Form Heterobimetallic Nanowires.

PubMed

Platero-Prats, Ana E; League, Aaron B; Bernales, Varinia; Ye, Jingyun; Gallington, Leighanne C; Vjunov, Aleksei; Schweitzer, Neil M; Li, Zhanyong; Zheng, Jian; Mehdi, B Layla; Stevens, Andrew J; Dohnalkova, Alice; Balasubramanian, Mahalingam; Farha, Omar K; Hupp, Joseph T; Browning, Nigel D; Fulton, John L; Camaioni, Donald M; Lercher, Johannes A; Truhlar, Donald G; Gagliardi, Laura; Cramer, Christopher J; Chapman, Karena W

2017-08-02

Metal-organic frameworks (MOFs), with their well-ordered pore networks and tunable surface chemistries, offer a versatile platform for preparing well-defined nanostructures wherein functionality such as catalysis can be incorporated. Notably, atomic layer deposition (ALD) in MOFs has recently emerged as a versatile approach to functionalize MOF surfaces with a wide variety of catalytic metal-oxo species. Understanding the structure of newly deposited species and how they are tethered within the MOF is critical to understanding how these components couple to govern the active material properties. By combining local and long-range structure probes, including X-ray absorption spectroscopy, pair distribution function analysis, and difference envelope density analysis, with electron microscopy imaging and computational modeling, we resolve the precise atomic structure of metal-oxo species deposited in the MOF NU-1000 through ALD. These analyses demonstrate that deposition of NiO x H y clusters occurs selectively within the smallest pores of NU-1000, between the zirconia nodes, serving to connect these nodes along the c-direction to yield heterobimetallic metal-oxo nanowires. This bridging motif perturbs the NU-1000 framework structure, drawing the zirconia nodes closer together, and also underlies the sintering resistance of these clusters during the hydrogenation of light olefins.

Bridging Zirconia Nodes within a Metal–Organic Framework via Catalytic Ni-Hydroxo Clusters to Form Heterobimetallic Nanowires

DOE PAGES

Platero-Prats, Ana E.; League, Aaron B.; Bernales, Varinia; ...

2017-07-11

Metal-organic frameworks (MOFs), with their well-ordered pore networks and tunable surface chemistries, offer a versatile platform for preparing well-defined nanostructures wherein functionality such as catalysis can be incorporated. Notably, atomic layer deposition (ALD) in MOFs has recently emerged as a versatile approach to functionalize MOF surfaces with a wide variety of catalytic metal-oxo species. Understanding the structure of newly deposited species and how they are tethered within the MOF is critical to understanding how these components couple to govern the active material properties. By combining local and long-range structure probes, including X-ray absorption spectroscopy, pair distribution function analysis and differencemore » envelope density analysis, with electron microscopy imag-ing and computational modeling, we resolve the precise atomic structure of metal-oxo species deposited in the MOF NU-1000 through ALD. These analyses demonstrate that deposition of NiO xH y clusters occurs selectively within the smallest pores of NU-1000, between the zirconia nodes, serving to connect these nodes along the c-direction to yield hetero-bimetallic metal-oxo nanowires. Finally, this bridging motif perturbs the NU-1000 framework structure, drawing the zirconia nodes closer together, and also underlies the sintering-resistance of these clusters during the hydrogenation of light olefins.« less

The β-Arrestins: Multifunctional Regulators of G Protein-coupled Receptors*

PubMed Central

Smith, Jeffrey S.; Rajagopal, Sudarshan

2016-01-01

The β-arrestins (βarrs) are versatile, multifunctional adapter proteins that are best known for their ability to desensitize G protein-coupled receptors (GPCRs), but also regulate a diverse array of cellular functions. To signal in such a complex fashion, βarrs adopt multiple conformations and are regulated at multiple levels to differentially activate downstream pathways. Recent structural studies have demonstrated that βarrs have a conserved structure and activation mechanism, with plasticity of their structural fold, allowing them to adopt a wide array of conformations. Novel roles for βarrs continue to be identified, demonstrating the importance of these dynamic regulators of cellular signaling. PMID:26984408

Nanoscale Graphene Disk: A Natural Functionally Graded Material–How is Fourier’s Law Violated along Radius Direction of 2D Disk

PubMed Central

Yang, Nuo; Hu, Shiqian; Ma, Dengke; Lu, Tingyu; Li, Baowen

2015-01-01

In this Paper, we investigate numerically and analytically the thermal conductivity of nanoscale graphene disks (NGDs), and discussed the possibility to realize functionally graded material (FGM) with only one material, NGDs. Different from previous studies on divergence/non-diffusive of thermal conductivity in nano-structures with different size, we found a novel non-homogeneous (graded) thermal conductivity along the radius direction in a single nano-disk structure. We found that, instead of a constant value, the NGD has a graded thermal conductivity along the radius direction. That is, Fourier’s law of heat conduction is not valid in two dimensional graphene disk structures Moreover, we show the dependent of NGDs’ thermal conductivity on radius and temperature. Our study might inspire experimentalists to develop NGD based versatile FGMs, improve understanding of the heat removal of hot spots on chips, and enhance thermoelectric energy conversion efficiency by two dimensional disk with a graded thermal conductivity. PMID:26443206

Nanoscale Graphene Disk: A Natural Functionally Graded Material-How is Fourier's Law Violated along Radius Direction of 2D Disk.

PubMed

Yang, Nuo; Hu, Shiqian; Ma, Dengke; Lu, Tingyu; Li, Baowen

2015-10-07

In this Paper, we investigate numerically and analytically the thermal conductivity of nanoscale graphene disks (NGDs), and discussed the possibility to realize functionally graded material (FGM) with only one material, NGDs. Different from previous studies on divergence/non-diffusive of thermal conductivity in nano-structures with different size, we found a novel non-homogeneous (graded) thermal conductivity along the radius direction in a single nano-disk structure. We found that, instead of a constant value, the NGD has a graded thermal conductivity along the radius direction. That is, Fourier's law of heat conduction is not valid in two dimensional graphene disk structures Moreover, we show the dependent of NGDs' thermal conductivity on radius and temperature. Our study might inspire experimentalists to develop NGD based versatile FGMs, improve understanding of the heat removal of hot spots on chips, and enhance thermoelectric energy conversion efficiency by two dimensional disk with a graded thermal conductivity.

Laser-Induced Molybdenum Carbide-Graphene Composites for 3D Foldable Paper Electronics.

PubMed

Zang, Xining; Shen, Caiwei; Chu, Yao; Li, Buxuan; Wei, Minsong; Zhong, Junwen; Sanghadasa, Mohan; Lin, Liwei

2018-05-15

Versatile and low-cost manufacturing processes/materials are essential for the development of paper electronics. Here, a direct-write laser patterning process is developed to make conductive molybdenum carbide-graphene (MCG) composites directly on paper substrates. The hierarchically porous MCG structures are converted from fibrous paper soaked with the gelatin-mediated inks containing molybdenum ions. The resulting Mo 3 C 2 and graphene composites are mechanically stable and electrochemically active for various potential applications, such as electrochemical ion detectors and gas sensors, energy harvesters, and supercapacitors. Experimentally, the electrical conductivity of the composite is resilient to mechanical deformation with less than 5% degradation after 750 cycles of 180° repeated folding tests. As such, the direct laser conversion of MCGs on papers can be applicable for paper-based electronics, including the 3D origami folding structures. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Reductive chemical release of N-glycans as 1-amino-alditols and subsequent 9-fluorenylmethyloxycarbonyl labeling for MS and LC/MS analysis.

PubMed

Wang, Chengjian; Qiang, Shan; Jin, Wanjun; Song, Xuezheng; Zhang, Ying; Huang, Linjuan; Wang, Zhongfu

2018-06-06

Glycoproteins play pivotal roles in a series of biological processes and their glycosylation patterns need to be structurally and functionally characterized. However, the lack of versatile methods to release N-glycans as functionalized forms has been undermining glycomics studies. Here a novel method is developed for dissociation of N-linked glycans from glycoproteins for analysis by MS and online LC/MS. This new method employs aqueous ammonia solution containing NaBH 3 CN as the reaction medium to release glycans from glycoproteins as 1-amino-alditol forms. The released glycans are conveniently labeled with 9-fluorenylmethyloxycarbonyl (Fmoc) and analyzed by ESI-MS and online LC/MS. Using the method, the neutral and acidic N-glycans were successfully released without peeling degradation of the core α-1,3-fucosylated structure or detectable de-N-acetylation, revealing its general applicability to various types of N-glycans. The Fmoc-derivatized N-glycans derived from chicken ovalbumin, Fagopyrum esculentum Moench Pollen and FBS were successfully analyzed by online LC/MS to distinguish isomers. The 1-amino-alditols were also permethylated to form quaternary ammonium cations at the reducing end, which enhance the MS sensitivity and are compatible with sequential multi-stage mass spectrometry (MS n ) fragmentation for glycan sequencing. The Fmoc-labeled N-glycans were further permethylated to produce methylated carbamates for determination of branches and linkages by sequential MS n fragmentation. N-Glycosylation represents one of the most common post-translational modification forms and plays pivotal roles in the structural and functional regulation of proteins in various biological activities, relating closely to human health and diseases. As a type of informational molecule, the N-glycans of glycoproteins participate directly in the molecular interactions between glycan epitopes and their corresponding protein receptors. Detailed structural and functional characterization of different types of N-glycans is essential for understanding the functional mechanisms of many biological activities and the pathologies of many diseases. Here we describe a simple, versatile method to indistinguishably release all types of N-glycans as functionalized forms without remarkable side reactions, enabling convenient, rapid analysis and preparation of released N-glycans from various complex biological samples. It is very valuable for studies on the complicated structure-function relationship of N-glycans, as well as for the search of N-glycan biomarkers of some major diseases and N-glycan related targets of some drugs. Copyright © 2018. Published by Elsevier B.V.

Interactive analysis and evaluation of ERTS data for regional planning and urban development: A Los Angeles Basin case study

NASA Technical Reports Server (NTRS)

Raje, S.; Economy, R.; Willoughby, G.; Mcknight, J.

1974-01-01

The progression endemic to the ERTS Data Use Experiment SR 124 in data quality, analysis sophistication and applications responsiveness is reviewed. The roles of the variety of ERTS products, including the supporting underflight aircraft imagery at various scales, are discussed in the context of this investigation. The versatility of interpretation techniques and outputs developed and implemented via the General Electric Multispectral Information Extraction Systems is described and exemplified by both system-expository and applications-explanatory products. The wide-ranging and in-depth applications studied in the course of this experiment can be characterized as community-oriented and agency-directed. In the former, generic category, which is primarily data-contextual, problems analyzed dealt with agricultural systems, surface water bodies, snow cover, brush fire burns, forestry, grass growth, parks - golf courses - cemeteries, dust storms, grading sites, geological features and coastal water structure. The ERTS MSS band selectivity and measurements thresholds were of primary interest here. The agency-directed application areas have been user-evaluational in nature. Beginning with overall urbanized regional analysis of land cover density-development intensity, residential areas were analyzed for ascertaining if housing types could be aggregated with any degree of reliability.

Roughness measurements on coupling structures for optical interconnections integrated on a printed circuit board

NASA Astrophysics Data System (ADS)

Hendrickx, Nina; Van Erps, Jürgen; Suyal, Himanshu; Taghizadeh, Mohammad; Thienpont, Hugo; Van Daele, Peter

2006-04-01

In this paper, laser ablation (at UGent), deep proton writing (at VUB) and laser direct writing (at HWU) are presented as versatile technologies that can be used for the fabrication of coupling structures for optical interconnections integrated on a printed circuit board (PCB). The optical layer, a highly cross-linked acrylate based polymer, is applied on an FR4 substrate. Both laser ablation and laser direct writing are used for the definition of arrays of multimode optical waveguides, which guide the light in the plane of the optical layer. In order to couple light vertically in/out of the plane of the optical waveguides, coupling structures have to be integrated into the optical layer. Out-of-plane turning mirrors, that deflect the light beam over 90°, are used for this purpose. The surface roughness and angle of three mirror configurations are evaluated: a laser ablated one that is integrated into the optical waveguide, a laser direct written one that is also directly written onto the waveguide and a DPW insert that is plugged into a cavity into the waveguiding layer.

Force-induced chemical reactions on the metal centre in a single metalloprotein molecule.

PubMed

Zheng, Peng; Arantes, Guilherme M; Field, Martin J; Li, Hongbin

2015-06-25

Metalloproteins play indispensable roles in biology owing to the versatile chemical reactivity of metal centres. However, studying their reactivity in many metalloproteins is challenging, as protein three-dimensional structure encloses labile metal centres, thus limiting their access to reactants and impeding direct measurements. Here we demonstrate the use of single-molecule atomic force microscopy to induce partial unfolding to expose metal centres in metalloproteins to aqueous solution, thus allowing for studying their chemical reactivity in aqueous solution for the first time. As a proof-of-principle, we demonstrate two chemical reactions for the FeS4 centre in rubredoxin: electrophilic protonation and nucleophilic ligand substitution. Our results show that protonation and ligand substitution result in mechanical destabilization of the FeS4 centre. Quantum chemical calculations corroborated experimental results and revealed detailed reaction mechanisms. We anticipate that this novel approach will provide insights into chemical reactivity of metal centres in metalloproteins under biologically more relevant conditions.

Force-induced chemical reactions on the metal centre in a single metalloprotein molecule

PubMed Central

Zheng, Peng; Arantes, Guilherme M.; Field, Martin J.; Li, Hongbin

2015-01-01

Metalloproteins play indispensable roles in biology owing to the versatile chemical reactivity of metal centres. However, studying their reactivity in many metalloproteins is challenging, as protein three-dimensional structure encloses labile metal centres, thus limiting their access to reactants and impeding direct measurements. Here we demonstrate the use of single-molecule atomic force microscopy to induce partial unfolding to expose metal centres in metalloproteins to aqueous solution, thus allowing for studying their chemical reactivity in aqueous solution for the first time. As a proof-of-principle, we demonstrate two chemical reactions for the FeS4 centre in rubredoxin: electrophilic protonation and nucleophilic ligand substitution. Our results show that protonation and ligand substitution result in mechanical destabilization of the FeS4 centre. Quantum chemical calculations corroborated experimental results and revealed detailed reaction mechanisms. We anticipate that this novel approach will provide insights into chemical reactivity of metal centres in metalloproteins under biologically more relevant conditions. PMID:26108369

Versatile Surface Functionalization of Metal-Organic Frameworks through Direct Metal Coordination with a Phenolic Lipid Enables Diverse Applications

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

Zhu, Wei; Xiang, Guolei; Shang, Jin

Here, a novel strategy for the versatile functionalization of the external surface of metal-organic frameworks (MOFs) has been developed based on the direct coordination of a phenolic-inspired lipid molecule DPGG (1,2-dipalmitoyl-sn-glycero-3-galloyl) with metal nodes/sites surrounding MOF surface. X-ray diffraction and Argon sorption analysis prove that the modified MOF particles retain their structural integrity and porosity after surface modification. Density functional theory calculations reveal that strong chelation strength between the metal sites and the galloyl head group of DPGG is the basic prerequisite for successful coating. Due to the pH-responsive nature of metal-phenol complexation, the modification process is reversible by simplemore » washing in weak acidic water, showing an excellent regeneration ability for water-stable MOFs. Moreover, the colloidal stability of the modified MOFs in the nonpolar solvent allows them to be further organized into 2 dimensional MOF or MOF/polymer monolayers by evaporation-induced interfacial assembly conducted on an air/water interface. Lastly, the easy fusion of a second functional layer onto DPGG-modified MOF cores, enabled a series of MOF-based functional nanoarchitectures, such as MOFs encapsulated within hybrid supported lipid bilayers (so-called protocells), polyhedral core-shell structures, hybrid lipid-modified-plasmonic vesicles and multicomponent supraparticles with target functionalities, to be generated. for a wide range of applications.« less

On how role versatility boosts an STI.

PubMed

Cortés, Andrés J

2017-12-19

The prevalence of the HIV-1 infection has decayed in the last decades in western heterosexual populations. However, among men who have sex with men (MSM) the prevalence is still high, despite intensive campaigns and treatment programs that keep infected men as undetectable (Beyrer et al. 2012). Promiscuity and condom fatigue (Adam et al. 2005), which are not unique to the MSM community, are making unprotected anal intercourse (UAI) more common and sexually transmitted infections (STIs) presumably harder to track. Yet, MSM communities are peculiar in the sense that men can adopt fixed (insertive or receptive) or versatile (both practices) roles. Some old theoretical work (Wiley & Herschkorn 1989, Van Druten et al. 1992, Trichopoulos et al. 1998) predicted that the transmission of HIV-1 would be enhanced in MSM populations engaged more in role versatility than in role segregation, in which fixed roles are predominantly adopted. These predictions were based on the assumption that the probability of acquisition from unprotected insertive anal (UIA) sex was neglectable. However, as later shown (Vittinghoff et al. 1999, Goodreau et al. 2005), this assumption is inappropriate and HIV-1 may still be acquired via UIA sex. Here I show through a stochastic model that the increase of the HIV-1 prevalence among MSM due to role versatility holds under a stronger assumption of bidirectional virus transmission. Copyright © 2017 Elsevier Ltd. All rights reserved.

Excitonic Properties of Chemically Synthesized 2D Organic-Inorganic Hybrid Perovskite Nanosheets.

PubMed

Zhang, Qi; Chu, Leiqiang; Zhou, Feng; Ji, Wei; Eda, Goki

2018-05-01

2D organic-inorganic hybrid perovskites (OIHPs) represent a unique class of materials with a natural quantum-well structure and quasi-2D electronic properties. Here, a versatile direct solution-based synthesis of mono- and few-layer OIHP nanosheets and a systematic study of their electronic structure as a function of the number of monolayers by photoluminescence and absorption spectroscopy are reported. The monolayers of various OIHPs are found to exhibit high electronic quality as evidenced by high quantum yield and negligible Stokes shift. It is shown that the ground exciton peak blueshifts by ≈40 meV when the layer thickness reduces from bulk to monolayer. It is also shown that the exciton binding energy remains effectively unchanged for (C 6 H 5 (CH 2 ) 2 NH 3 ) 2 PbI 4 with the number of layers. Similar trends are observed for (C 4 H 9 NH 3 ) 2 PbI 4 in contrast to the previous report. Further, the photoluminescence lifetime is found to decrease with the number of monolayers, indicating the dominant role of surface trap states in nonradiative recombination of the electron-hole pairs. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis of one-dimensional metal-containing insulated molecular wire with versatile properties directed toward molecular electronics materials.

PubMed

Masai, Hiroshi; Terao, Jun; Seki, Shu; Nakashima, Shigeto; Kiguchi, Manabu; Okoshi, Kento; Fujihara, Tetsuaki; Tsuji, Yasushi

2014-02-05

We report, herein, the design, synthesis, and properties of new materials directed toward molecular electronics. A transition metal-containing insulated molecular wire was synthesized through the coordination polymerization of a Ru(II) porphyrin with an insulated bridging ligand of well-defined structure. The wire displayed not only high linearity and rigidity, but also high intramolecular charge mobility. Owing to the unique properties of the coordination bond, the interconversion between the monomer and polymer states was realized under a carbon monoxide atmosphere or UV irradiation. The results demonstrated a high potential of the metal-containing insulated molecular wire for applications in molecular electronics.

Could the increased structural versatility imposed by non-halogen ligands bring something new for polynuclear superhalogens? A case study on binuclear [Mg2L5]- (L = -OH, -OOH and -OF) anions.

PubMed

Zhao, Ru-Fang; Yu, Le; Zhou, Fu-Qiang; Li, Jin-Feng; Yin, Bing

2017-10-11

A combined ab initio and DFT study is performed in this work to explore the superhalogen properties of polynuclear structures based on the ligands of -OH, -OOH and -OF. According to high-level CCSD(T) results, all the structures here are superhalogens whose properties are superior to the corresponding mononuclear ones. Although inferior to similar structures based on F ligands, some of the superhalogens here are capable of transcending the traditional ones based on Cl atoms. Therefore the superhalogen properties of the anions here are still promising and they have an important advantage of high safety, which is crucial for practical applications. An increased degree of structural versatility is imposed by these non-halogen ligands because of the various ways in which they connect the central atoms and their multiple orientations. It is important that this increased versatility will bring new factors, e.g., the larger spatial extent of the whole cluster and the existence of intra-molecular hydrogen bonds, which should favour high VDE values. These factors are not available in traditional halogen-based systems and they may play an important role in the future search for novel superhalogens. (HF + MP2)/2, ωB97XD as well as M06-2X are capable of providing accurate VDE values, close to the CCSD(T) results, and their absolute errors are even lower than that of the OVGF. Due to the good balance between the accuracy and efficiency, these methods could provide reliable predictions on large systems which cannot be treated with CCSD(T) or even with the OVGF. Balanced distribution of the extra electron, between the terminal and bridging ligands, is also shown to be favourable to realize a high VDE value.

Materials taking a lesson from nature.

PubMed

Tian, Liangfei; Croisier, Emmanuel; Frauenrath, Holger

2013-01-01

Structural biomaterials with their often extraordinary properties and versatile functions are typically constructed from very limited sets of building blocks and types of supramolecular interactions. In this review we discuss how, inspired by nature's design principles for protein-based materials, oligopeptide-modified polymers can be used as a versatile toolbox to program nanostructure and hierarchical structure formation in synthetic materials.

Origami: A Versatile Modeling System for Visualising Chemical Structure and Exploring Molecular Function

ERIC Educational Resources Information Center

Davis, James; Leslie, Ray; Billington, Susan; Slater, Peter R.

2010-01-01

The use of "Origami" is presented as an accessible and transferable modeling system through which to convey the intricacies of molecular shape and highlight structure-function relationships. The implementation of origami has been found to be a versatile alternative to conventional ball-and-stick models, possessing the key advantages of being both…

The acoustic vector sensor: a versatile battlefield acoustics sensor

NASA Astrophysics Data System (ADS)

de Bree, Hans-Elias; Wind, Jelmer W.

2011-06-01

The invention of the Microflown sensor has made it possible to measure acoustic particle velocity directly. An acoustic vector sensor (AVS) measures the particle velocity in three directions (the source direction) and the pressure. The sensor is a uniquely versatile battlefield sensor because its size is a few millimeters and it is sensitive to sound from 10Hz to 10kHz. This article shows field tests results of acoustic vector sensors, measuring rifles, heavy artillery, fixed wing aircraft and helicopters. Experimental data shows that the sensor is suitable as a ground sensor, mounted on a vehicle and on a UAV.

Two-port active coupled microstrip antenna

NASA Astrophysics Data System (ADS)

Avitabile, G. F.; Maci, S.; Biffi Gentili, G.; Roselli, L.; Manes, G. F.

1992-12-01

A multilayer structure, based on a patch antenna coupled through a nonresonant slot to a pair of feeding microstrips is a versatile module which can be used as a radiating and resonating element in a number of different configurations. Direct connection to a low cost transistor in a feedback loop results in a very simple active antenna, as reported in the Letter. Different termination conditions at the four microstrip ports give rise to a number of alternative configurations for active generation/detection and multipatch arrays.

Modern Technologies for Creating Synthetic Antibodies for Clinical application

PubMed Central

Lebedenko, E. N.

2009-01-01

The modular structure and versatility of antibodies enables one to modify natural immunoglobulins in different ways for various clinical applications. Rational design and molecular engineering make it possible to directionally modify the molecular size, affinity, specificity, and immunogenicity and effector functions of an antibody, as well as to combine them with other functional agents. This review focuses on up-to-date methods of antibody engineering for diagnosing and treating various diseases, particularly on new technologies meant to refine the effector functions of therapeutic antibodies. PMID:22649585

PMR polyimides: Processable high temperature composite matrix resins

NASA Technical Reports Server (NTRS)

Winters, W. E.; Serafini, T. T.

1975-01-01

Processing reproducibility and versatility were demonstrated for producing addition-cured polyimide/graphite fiber composites using an in situ polymerization of monomeric reactants directly on the fiber surface. The polymers so derived, designated PMR polyimides, can be fabricated into composite structures by laminating, random fiber molding or autoclave curing. Composites were determined to be thermally stable and retain useful properties after extended exposures at 550 F to 650 F. The material and fabrication capability were demonstrated by the fabrication and evaluation of prototype complex fan blades.

PMR polyimides - Processable high temperature composite matrix resins

NASA Technical Reports Server (NTRS)

Winters, W. E.; Serafini, T. T.

1975-01-01

Processing reproducibility and versatility were demonstrated for producing addition-cured polyimide/graphite fiber composites using a unique in situ polymerization of monomeric reactants directly on the fiber surface. The polymers so derived, designated PMR polyimides, can be fabricated into composite structures by laminating, random fiber molding or autoclave curing. Composites were determined to be thermally stable and retain useful properties after extended exposures at 550 to 650 F. The material and fabrication capability were demonstrated by the fabrication and evaluation of prototype complex fan blades.-

The β-Arrestins: Multifunctional Regulators of G Protein-coupled Receptors.

PubMed

Smith, Jeffrey S; Rajagopal, Sudarshan

2016-04-22

The β-arrestins (βarrs) are versatile, multifunctional adapter proteins that are best known for their ability to desensitize G protein-coupled receptors (GPCRs), but also regulate a diverse array of cellular functions. To signal in such a complex fashion, βarrs adopt multiple conformations and are regulated at multiple levels to differentially activate downstream pathways. Recent structural studies have demonstrated that βarrs have a conserved structure and activation mechanism, with plasticity of their structural fold, allowing them to adopt a wide array of conformations. Novel roles for βarrs continue to be identified, demonstrating the importance of these dynamic regulators of cellular signaling. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

The Occupational Versatility Program: Student-Directed Learning in Industrial Arts.

ERIC Educational Resources Information Center

Lavender, John

1978-01-01

Describes the Occupational Versatility program in industrial arts, involving a self-instructional school shop in which the learning system is student-managed, nongraded, upgraded, and team taught. This federally funded learning method has also been successfully applied to home economics and art education. Information sources for the teacher are…

Whistler Mode Based Explanation for the Fast Reconnection Rate Measured in the MIT Versatile Toroidal Facility

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

Singh, Nagendra

2011-12-09

Despite the widely discussed role of whistler waves in mediating magnetic reconnection (MR), the direct connection between such waves and the MR has not been demonstrated by comparing the characteristic temporal and spatial features of the waves and the MR process. Using the whistler wave dispersion relation, we theoretically predict the experimentally measured rise time ({tau}{sub rise}) of a few microseconds for the fast rising MR rate in the Versatile Toroidal Facility at MIT. The rise time is closely given by the inverse of the frequency bandwidth of the whistler waves generated in the evolving current sheet. The wave frequenciesmore » lie much above the ion cyclotron frequency, but they are limited to less than 0.1% of the electron cyclotron frequency in the argon plasma. The maximum normalized MR rate R=0.35 measured experimentally is precisely predicted by the angular dispersion of the whistler waves.« less

Imprintable, bendable, and shape-conformable polymer electrolytes for versatile-shaped lithium-ion batteries.

PubMed

Kil, Eun-Hye; Choi, Keun-Ho; Ha, Hyo-Jeong; Xu, Sheng; Rogers, John A; Kim, Mi Ri; Lee, Young-Gi; Kim, Kwang Man; Cho, Kuk Young; Lee, Sang-Young

2013-03-13

A class of imprintable, bendable, and shape-conformable polymer electrolyte with excellent electrochemical performance in a lithium battery system is reported. The material consists of a UV-cured polymer matrix, high-boiling point liquid electrolyte, and Al2 O3 nanoparticles, formulated for use in lithium-ion batteries with 3D-structured electrodes or flexible characteristics. The unique structural design and well-tuned rheological characteristics of the UV-curable electrolyte mixture, in combination with direct UV-assisted nanoimprint lithography, allow the successful fabrication of polymer electrolytes in geometries not accessible with conventional materials. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Volatile terpenoids: multiple functions, biosynthesis, modulation and manipulation by genetic engineering.

PubMed

Abbas, Farhat; Ke, Yanguo; Yu, Rangcai; Yue, Yuechong; Amanullah, Sikandar; Jahangir, Muhammad Muzammil; Fan, Yanping

2017-11-01

Terpenoids play several physiological and ecological functions in plant life through direct and indirect plant defenses and also in human society because of their enormous applications in the pharmaceutical, food and cosmetics industries. Through the aid of genetic engineering its role can by magnified to broad spectrum by improving genetic ability of crop plants, enhancing the aroma quality of fruits and flowers and the production of pharmaceutical terpenoids contents in medicinal plants. Terpenoids are structurally diverse and the most abundant plant secondary metabolites, playing an important role in plant life through direct and indirect plant defenses, by attracting pollinators and through different interactions between the plants and their environment. Terpenoids are also significant because of their enormous applications in the pharmaceutical, food and cosmetics industries. Due to their broad distribution and functional versatility, efforts are being made to decode the biosynthetic pathways and comprehend the regulatory mechanisms of terpenoids. This review summarizes the recent advances in biosynthetic pathways, including the spatiotemporal, transcriptional and post-transcriptional regulatory mechanisms. Moreover, we discuss the multiple functions of the terpene synthase genes (TPS), their interaction with the surrounding environment and the use of genetic engineering for terpenoid production in model plants. Here, we also provide an overview of the significance of terpenoid metabolic engineering in crop protection, plant reproduction and plant metabolic engineering approaches for pharmaceutical terpenoids production and future scenarios in agriculture, which call for sustainable production platforms by improving different plant traits.

The respective roles of polar/nonpolar binary patterns and amino acid composition in protein regular secondary structures explored exhaustively using hydrophobic cluster analysis.

PubMed

Rebehmed, Joseph; Quintus, Flavien; Mornon, Jean-Paul; Callebaut, Isabelle

2016-05-01

Several studies have highlighted the leading role of the sequence periodicity of polar and nonpolar amino acids (binary patterns) in the formation of regular secondary structures (RSS). However, these were based on the analysis of only a few simple cases, with no direct mean to correlate binary patterns with the limits of RSS. Here, HCA-derived hydrophobic clusters (HC) which are conditioned binary patterns whose positions fit well those of RSS, were considered. All the HC types, defined by unique binary patterns, which were commonly observed in three-dimensional (3D) structures of globular domains, were analyzed. The 180 HC types with preferences for either α-helices or β-strands distinctly contain basic binary units typical of these RSS. Therefore a general trend supporting the "binary pattern preference" assumption was observed. HC for which observed RSS are in disagreement with their expected behavior (discordant HC) were also examined. They were separated in HC types with moderate preferences for RSS, having "weak" binary patterns and versatile RSS and HC types with high preferences for RSS, having "strong" binary patterns and then displaying nonpolar amino acids at the protein surface. It was shown that in both cases, discordant HC could be distinguished from concordant ones by well-differentiated amino acid compositions. The obtained results could, thus, help to complement the currently available methods for the accurate prediction of secondary structures in proteins from the only information of a single amino acid sequence. This can be especially useful for characterizing orphan sequences and for assisting protein engineering and design. © 2016 Wiley Periodicals, Inc.

A multifaceted FISH approach to study endogenous RNAs and DNAs in native nuclear and cell structures.

PubMed

Byron, Meg; Hall, Lisa L; Lawrence, Jeanne B

2013-01-01

Fluorescence in situ hybridization (FISH) is not a singular technique, but a battery of powerful and versatile tools for examining the distribution of endogenous genes and RNAs in precise context with each other and in relation to specific proteins or cell structures. This unit offers the details of highly sensitive and successful protocols that were initially developed largely in our lab and honed over a number of years. Our emphasis is on analysis of nuclear RNAs and DNA to address specific biological questions about nuclear structure, pre-mRNA metabolism, or the role of noncoding RNAs; however, cytoplasmic RNA detection is also discussed. Multifaceted molecular cytological approaches bring precise resolution and sensitive multicolor detection to illuminate the organization and functional roles of endogenous genes and their RNAs within the native structure of fixed cells. Solutions to several common technical pitfalls are discussed, as are cautions regarding the judicious use of digital imaging and the rigors of analyzing and interpreting complex molecular cytological results.

Structure-function studies on the active site of the coelenterazine-dependent luciferase from Renilla.

PubMed

Woo, Jongchan; Howell, Matthew H; von Arnim, Albrecht G

2008-04-01

Renilla luciferase (RLUC) is a versatile tool for gene expression assays and in vivo biosensor applications, but its catalytic mechanism remains to be elucidated. RLUC is evolutionarily related to the alpha/beta hydrolase family. Its closest known homologs are bacterial dehalogenases, raising the question of how a protein with a hydrolase fold can function as a decarboxylating oxygenase. Molecular docking simulations with the coelenterazine substrate against an RLUC homology model as well as a recently determined RLUC crystal structure were used to build hypotheses to identify functionally important residues, which were subsequently tested by site-directed mutagenesis, heterologous expression, and bioluminescence emission spectroscopy. The data highlighted two triads of residues that are critical for catalysis. The putative catalytic triad residues D120, E144, and H285 bear only limited resemblance to those found in the active site of aequorin, a coelenterazine-utilizing photoprotein, suggesting that the reaction scheme employed by RLUC differs substantially from the one established for aequorin. The role of H285 in catalysis was further supported by inhibition using diethylpyrocarbonate. Multiple substitutions of N53, W121, and P220--three other residues implicated in product binding in the homologous dehalogenase Sphingomonas LinB--also supported their involvement in catalysis. Together with luminescence spectra, our data lead us to propose that the conserved catalytic triad of RLUC is directly involved in the decarboxylation reaction of coelenterazine to produce bioluminescence, while the other active-site residues are used for binding of the substrate.

Plasma-electric field controlled growth of oriented graphene for energy storage applications

NASA Astrophysics Data System (ADS)

Ghosh, Subrata; Polaki, S. R.; Kamruddin, M.; Jeong, Sang Mun; (Ken Ostrikov, Kostya

2018-04-01

It is well known that graphene grows as flat sheets aligned with the growth substrate. Oriented graphene structures typically normal to the substrate have recently attracted major attention. Most often, the normal orientation is achieved in a plasma-assisted growth and is believed to be due to the plasma-induced in-built electric field, which is usually oriented normal to the substrate. This work focuses on the effect of an in-built electric field on the growth direction, morphology, interconnectedness, structural properties and also the supercapacitor performance of various configurations of graphene structures and reveals the unique dependence of these features on the electric field orientation. It is shown that tilting of growth substrates from parallel to the normal direction with respect to the direction of in-built plasma electric field leads to the morphological transitions from horizontal graphene layers, to oriented individual graphene sheets and then interconnected 3D networks of oriented graphene sheets. The revealed transition of the growth orientation leads to a change in structural properties, wetting nature, types of defect in graphitic structures and also affects their charge storage capacity when used as supercapacitor electrodes. This simple and versatile approach opens new opportunities for the production of potentially large batches of differently oriented and structured graphene sheets in one production run.

Automated Generation of Finite-Element Meshes for Aircraft Conceptual Design

NASA Technical Reports Server (NTRS)

Li, Wu; Robinson, Jay

2016-01-01

This paper presents a novel approach for automated generation of fully connected finite-element meshes for all internal structural components and skins of a given wing-body geometry model, controlled by a few conceptual-level structural layout parameters. Internal structural components include spars, ribs, frames, and bulkheads. Structural layout parameters include spar/rib locations in wing chordwise/spanwise direction and frame/bulkhead locations in longitudinal direction. A simple shell thickness optimization problem with two load conditions is used to verify versatility and robustness of the automated meshing process. The automation process is implemented in ModelCenter starting from an OpenVSP geometry and ending with a NASTRAN 200 solution. One subsonic configuration and one supersonic configuration are used for numerical verification. Two different structural layouts are constructed for each configuration and five finite-element meshes of different sizes are generated for each layout. The paper includes various comparisons of solutions of 20 thickness optimization problems, as well as discussions on how the optimal solutions are affected by the stress constraint bound and the initial guess of design variables.

Inactivation of a Pleurotus ostreatus versatile peroxidase-encoding gene (mnp2) results in reduced lignin degradation.

PubMed

Salame, Tomer M; Knop, Doriv; Levinson, Dana; Mabjeesh, Sameer J; Yarden, Oded; Hadar, Yitzhak

2014-01-01

Lignin biodegradation by white-rot fungi is pivotal to the earth's carbon cycle. Manganese peroxidases (MnPs), the most common extracellular ligninolytic peroxidases produced by white-rot fungi, are considered key in ligninolysis. Pleurotus ostreatus, the oyster mushroom, is a preferential lignin degrader occupying niches rich in lignocellulose such as decaying trees. Here, we provide direct, genetically based proof for the functional significance of MnP to P. ostreatus ligninolytic capacity under conditions mimicking its natural habitat. When grown on a natural lignocellulosic substrate of cotton stalks under solid-state culture conditions, gene and isoenzyme expression profiles of its short MnP and versatile peroxidase (VP)-encoding gene family revealed that mnp2 was predominately expressed. mnp2, encoding the versatile short MnP isoenzyme 2 was disrupted. Inactivation of mnp2 resulted in three interrelated phenotypes, relative to the wild-type strain: (i) reduction of 14% and 36% in lignin mineralization of stalks non-amended and amended with Mn(2+), respectively; (ii) marked reduction of the bioconverted lignocellulose sensitivity to subsequent bacterial hydrolyses; and (iii) decrease in fungal respiration rate. These results may serve as the basis to clarify the roles of the various types of fungal MnPs and VPs in their contribution to white-rot decay of wood and lignocellulose in various ecosystems. © 2013 Society for Applied Microbiology and John Wiley & Sons Ltd.

A novel embeddable spherical smart aggregate for structural health monitoring: part I. Fabrication and electrical characterization

NASA Astrophysics Data System (ADS)

Kong, Qingzhao; Fan, Shuli; Bai, Xiaolong; Mo, Y. L.; Song, Gangbing

2017-09-01

Recently developed piezoceramic-based transducers, known as smart aggregates (SAs), have shown their applicability and versatility in various applications of structural health monitoring (SHM). The lead zirconate titanate (PZT) patches embedded inside SAs have different modes that are more suitable for generating or receiving different types of stress waves (e.g. P and S waves, each of which has a unique role in SHM). However, due to the geometry of the 2D PZT patch, the embedded SA can only generate or receive the stress wave in a single direction and thus greatly limits its applications. This paper is the first of a series of two companion papers that introduces the authors’ latest work in developing a novel, embeddable spherical smart aggregate (SSA) for the health monitoring of concrete structures. In addition to the 1D guided wave produced by SA, the SSA embedded in concrete structures can generate or receive omni-directional stress waves that can significantly improve the detection aperture and provide additional functionalities in SHM. In the first paper (Part I), the detailed fabrication procedures with the help of 3D printing technology and electrical characterization of the proposed SSA is presented. The natural frequencies of the SSA were experimentally obtained and further compared with the numerical results. In addition, the influence of the components’ thickness (spherical piezoceramic shell and epoxy) and outer radius (spherical piezoceramic shell and protection concrete) on the natural frequencies of the SSA were analytically studied. The results will help elucidate the key parameters that determine the natural frequencies of the SSA. The natural frequencies of the SSA can thus be designed for suitability in the damage detection of concrete structures. In the second paper (Part II), further numerical and experimental verifications on the performance of the proposed SSA in concrete structures will be discussed.

Pore Breathing of Metal-Organic Frameworks by Environmental Transmission Electron Microscopy.

PubMed

Parent, Lucas R; Pham, C Huy; Patterson, Joseph P; Denny, Michael S; Cohen, Seth M; Gianneschi, Nathan C; Paesani, Francesco

2017-10-11

Metal-organic frameworks (MOFs) have emerged as a versatile platform for the rational design of multifunctional materials, combining large specific surface areas with flexible, periodic frameworks that can undergo reversible structural transitions, or "breathing", upon temperature and pressure changes, and through gas adsorption/desorption processes. Although MOF breathing can be inferred from the analysis of adsorption isotherms, direct observation of the structural transitions has been lacking, and the underlying processes of framework reorganization in individual MOF nanocrystals is largely unknown. In this study, we describe the characterization and elucidation of these processes through the combination of in situ environmental transmission electron microscopy (ETEM) and computer simulations. This combined approach enables the direct monitoring of the breathing behavior of individual MIL-53(Cr) nanocrystals upon reversible water adsorption and temperature changes. The ability to characterize structural changes in single nanocrystals and extract lattice level information through in silico correlation provides fundamental insights into the relationship between pore size/shape and host-guest interactions.

Nucleobases, nucleosides, and nucleotides: versatile biomolecules for generating functional nanomaterials.

PubMed

Pu, Fang; Ren, Jinsong; Qu, Xiaogang

2018-02-21

The incorporation of biomolecules into nanomaterials generates functional nanosystems with novel and advanced properties, presenting great potential for applications in various fields. Nucleobases, nucleosides and nucleotides, as building blocks of nucleic acids and biological coenzymes, constitute necessary components of the foundation of life. In recent years, as versatile biomolecules for the construction or regulation of functional nanomaterials, they have stimulated interest in researchers, due to their unique properties such as structural diversity, multiplex binding sites, self-assembly ability, stability, biocompatibility, and chirality. In this review, strategies for the synthesis of nanomaterials and the regulation of their morphologies and functions using nucleobases, nucleosides, and nucleotides as building blocks, templates or modulators are summarized alongside selected applications. The diverse applications range from sensing, bioimaging, and drug delivery to mimicking light-harvesting antenna, the construction of logic gates, and beyond. Furthermore, some perspectives and challenges in this emerging field are proposed. This review is directed toward the broader scientific community interested in biomolecule-based functional nanomaterials.

Designing a Bio-responsive Robot from DNA Origami

PubMed Central

Ben-Ishay, Eldad; Abu-Horowitz, Almogit; Bachelet, Ido

2013-01-01

Nucleic acids are astonishingly versatile. In addition to their natural role as storage medium for biological information1, they can be utilized in parallel computing2,3 , recognize and bind molecular or cellular targets4,5 , catalyze chemical reactions6,7 , and generate calculated responses in a biological system8,9. Importantly, nucleic acids can be programmed to self-assemble into 2D and 3D structures10-12, enabling the integration of all these remarkable features in a single robot linking the sensing of biological cues to a preset response in order to exert a desired effect. Creating shapes from nucleic acids was first proposed by Seeman13, and several variations on this theme have since been realized using various techniques11,12,14,15 . However, the most significant is perhaps the one proposed by Rothemund, termed scaffolded DNA origami16. In this technique, the folding of a long (>7,000 bases) single-stranded DNA 'scaffold' is directed to a desired shape by hundreds of short complementary strands termed 'staples'. Folding is carried out by temperature annealing ramp. This technique was successfully demonstrated in the creation of a diverse array of 2D shapes with remarkable precision and robustness. DNA origami was later extended to 3D as well17,18 . The current paper will focus on the caDNAno 2.0 software19 developed by Douglas and colleagues. caDNAno is a robust, user-friendly CAD tool enabling the design of 2D and 3D DNA origami shapes with versatile features. The design process relies on a systematic and accurate abstraction scheme for DNA structures, making it relatively straightforward and efficient. In this paper we demonstrate the design of a DNA origami nanorobot that has been recently described20. This robot is 'robotic' in the sense that it links sensing to actuation, in order to perform a task. We explain how various sensing schemes can be integrated into the structure, and how this can be relayed to a desired effect. Finally we use Cando21 to simulate the mechanical properties of the designed shape. The concept we discuss can be adapted to multiple tasks and settings. PMID:23893007

Nonlinear random response prediction using MSC/NASTRAN

NASA Technical Reports Server (NTRS)

Robinson, J. H.; Chiang, C. K.; Rizzi, S. A.

1993-01-01

An equivalent linearization technique was incorporated into MSC/NASTRAN to predict the nonlinear random response of structures by means of Direct Matrix Abstract Programming (DMAP) modifications and inclusion of the nonlinear differential stiffness module inside the iteration loop. An iterative process was used to determine the rms displacements. Numerical results obtained for validation on simple plates and beams are in good agreement with existing solutions in both the linear and linearized regions. The versatility of the implementation will enable the analyst to determine the nonlinear random responses for complex structures under combined loads. The thermo-acoustic response of a hexagonal thermal protection system panel is used to highlight some of the features of the program.

Site-Specific Pre-Swelling-Directed Morphing Structures of Patterned Hydrogels.

PubMed

Wang, Zhi Jian; Hong, Wei; Wu, Zi Liang; Zheng, Qiang

2017-12-11

Morphing materials have promising applications in various fields, yet how to program the self-shaping process for specific configurations remains a challenge. Herein we show a versatile approach to control the buckling of individual domains and thus the outcome configurations of planar-patterned hydrogels. By photolithography, high-swelling disc gels were positioned in a non-swelling gel sheet; the swelling mismatch resulted in out-of-plain buckling of the disc gels. To locally control the buckling direction, masks with holes were used to guide site-specific swelling of the high-swelling gel under the holes, which built a transient through-thickness gradient and thus directed the buckling during the subsequent unmasked swelling process. Therefore, various configurations of an identical patterned hydrogel can be programmed by the pre-swelling step with different masks to encode the buckling directions of separate domains. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Origami acoustics: using principles of folding structural acoustics for simple and large focusing of sound energy

NASA Astrophysics Data System (ADS)

Harne, Ryan L.; Lynd, Danielle T.

2016-08-01

Fixed in spatial distribution, arrays of planar, electromechanical acoustic transducers cannot adapt their wave energy focusing abilities unless each transducer is externally controlled, creating challenges for the implementation and portability of such beamforming systems. Recently, planar, origami-based structural tessellations are found to facilitate great versatility in system function and properties through kinematic folding. In this research we bridge the physics of acoustics and origami-based design to discover that the simple topological reconfigurations of a Miura-ori-based acoustic array yield many orders of magnitude worth of reversible change in wave energy focusing: a potential for acoustic field morphing easily obtained through deployable, tessellated architectures. Our experimental and theoretical studies directly translate the roles of folding the tessellated array to the adaptations in spectral and spatial wave propagation sensitivities for far field energy transmission. It is shown that kinematic folding rules and flat-foldable tessellated arrays collectively provide novel solutions to the long-standing challenges of conventional, electronically-steered acoustic beamformers. While our examples consider sound radiation from the foldable array in air, linear acoustic reciprocity dictates that the findings may inspire new innovations for acoustic receivers, e.g. adaptive sound absorbers and microphone arrays, as well as concepts that include water-borne waves.

Photoinitiated Bottom-Up Click Synthesis of Ion-Containing Networks as Hydroxide Exchange Membranes

NASA Astrophysics Data System (ADS)

Tibbits, Andrew Charles

Fuel cells are energy conversion devices which directly convert chemical energy into electrical energy and environmentally friendly byproducts (i.e., water) with potential versatility for transportation and portable applications. Hydroxide exchange membrane fuel cells (HEMFCs) have the potential to decrease the overall fuel cell cost through the utilization of non-precious metal catalysts such as nickel and silver as opposed to platinum which is used by the current standard technology, proton exchange membrane fuel cells (PEMFCs). However, substantial improvements in thermal and alkaline stability, hydroxide conductivity, mechanical flexibility, and processing are needed to create a competitive membrane for HEMFC applications. Regardless of the type of membrane, the high water uptake that is typically associated with increased ionic conductivity is problematic and can result in the dissolution of the membrane during fuel cell operation. Covalent crosslinking of the membrane is an approach which has been effectively applied to reduce water uptake without a significant compromise of the hydroxide conductivity. The synthesis and processing of membrane materials is vastly simplified by using click polymerization schemes. Click chemistry is a collection of organic chemical reactions that are rapid, selective, and high yielding. One of the most versatile and facile click reactions is the thiol-ene reaction, which is the radical-mediated addition reaction between a thiol (an -SH group) and an 'ene' (an electron rich vinyl group, C=C) in the presence of a photoinitiator and light. The click attributes of the thiol-ene reaction enables potential of "bottom-up" design of ion-containing polymers via a single step photoinitiated crosslinking reaction with precise control over structure and physicochemical properties not only for fuel cell membranes but also for a range of other applications including separations, sensors, flexible electronics, and coatings. However, a fundamental understanding of the formation and properties of ion-containing thiol-ene materials and their implementation as hydroxide exchange membranes is largely absent from the current literature. The work described herein will highlight the versatility of click reactions, primarily the thiol-ene reaction, for fabrication of ion-containing networks with tunable properties based on the rational design and synthesis of photopolymerizable ionic liquid comonomers with an emphasis on applicability for HEMFC applications. The role of ionic liquid monomer structure on the kinetics and mechanism of thiol-ene ionic network formation and the subsequent properties (i.e., ion conductive, thermomechanical, and structural) will be elucidated to establish a guided framework for click ionic material development. This framework will be directed onto the development of alkaline stable hydroxide-conductive membranes for fuel cell applications as well as the incorporation of catalytic nanoparticles into a photocrosslinkable formulation as a self-standing catalyst layer. Finally, novel approaches to membrane fabrication will be implemented to build on the foundational studies that will simultaneously enhance the ionic conductivity and mechanical properties of the ion-containing polymer materials: these approaches include the synthesis and crosslinking of photopolymerizable cationic surfactants for microphase separated membranes as well as the first "bottom-up" ion-containing polymer synthesized from the photoinitiated copper-catalyzed azide-alkyne cycloaddition (photo-CuAAC) reaction which exhibits enhanced processability and hydroxide conductivity (>50 mS/cm).

A versatile digitally-graded buffer structure for metamorphic device applications

NASA Astrophysics Data System (ADS)

Ma, Yingjie; Zhang, Yonggang; Chen, Xingyou; Gu, Yi; Shi, Yanhui; Ji, Wanyan; Du, Ben

2018-04-01

Exploring more effective buffer schemes for mitigating dislocation deficiencies is the key technology towards higher performance metamorphic devices. Here we demonstrate a versatile metamorphic grading structure consisting of 38-period alternated multilayers of In0.52Al0.48As and In0.82Al0.18As on InP substrate, thicknesses of which in each period were gradually varied in opposite directions from 48.7 and 1.3 nm to 1.3 and 48.7 nm, respectively, akin to a digital alloy. Both preferentially dislocation nucleation and blocking of threading dislocation transmission are observed near the In0.82Al0.18As/In0.52Al0.48As interfaces, which help relax the strain and lower the residual defect density. A 2.6 μm In0.83Ga0.17As pin photodetector is fabricated on this pseudo-substrate, attaining a low dark current density of 2.9  ×  10‑6 A cm‑2 and a high detectivity of 1.8  ×  1010 cmHz1/2W‑1 at room temperature, comparable with the states of the art that on linearly-graded buffer layers. These results indicate such digitally-graded buffer structures are promising for enhancing performances of metamorphic devices, and can be easily generalized to other lattice-mismatched material systems.

Photoacoustics of single laser-trapped nanodroplets for the direct observation of nanofocusing in aerosol photokinetics

NASA Astrophysics Data System (ADS)

Cremer, Johannes W.; Thaler, Klemens M.; Haisch, Christoph; Signorell, Ruth

2016-03-01

Photochemistry taking place in atmospheric aerosol droplets has a significant impact on the Earth's climate. Nanofocusing of electromagnetic radiation inside aerosols plays a crucial role in their absorption behaviour, since the radiation flux inside the droplet strongly affects the activation rate of photochemically active species. However, size-dependent nanofocusing effects in the photokinetics of small aerosols have escaped direct observation due to the inability to measure absorption signatures from single droplets. Here we show that photoacoustic measurements on optically trapped single nanodroplets provide a direct, broadly applicable method to measure absorption with attolitre sensitivity. We demonstrate for a model aerosol that the photolysis is accelerated by an order of magnitude in the sub-micron to micron size range, compared with larger droplets. The versatility of our technique promises broad applicability to absorption studies of aerosol particles, such as atmospheric aerosols where quantitative photokinetic data are critical for climate predictions.

Photoacoustics of single laser-trapped nanodroplets for the direct observation of nanofocusing in aerosol photokinetics

PubMed Central

Cremer, Johannes W.; Thaler, Klemens M.; Haisch, Christoph; Signorell, Ruth

2016-01-01

Photochemistry taking place in atmospheric aerosol droplets has a significant impact on the Earth's climate. Nanofocusing of electromagnetic radiation inside aerosols plays a crucial role in their absorption behaviour, since the radiation flux inside the droplet strongly affects the activation rate of photochemically active species. However, size-dependent nanofocusing effects in the photokinetics of small aerosols have escaped direct observation due to the inability to measure absorption signatures from single droplets. Here we show that photoacoustic measurements on optically trapped single nanodroplets provide a direct, broadly applicable method to measure absorption with attolitre sensitivity. We demonstrate for a model aerosol that the photolysis is accelerated by an order of magnitude in the sub-micron to micron size range, compared with larger droplets. The versatility of our technique promises broad applicability to absorption studies of aerosol particles, such as atmospheric aerosols where quantitative photokinetic data are critical for climate predictions. PMID:26979973

Role of Intramolecular Aromatic π-π Interactions in the Self-Assembly of Di-l-Phenylalanine Dipeptide Driven by Intermolecular Interactions: Effect of Alanine Substitution.

PubMed

Reddy, Samala Murali Mohan; Shanmugam, Ganesh

2016-09-19

Although the role of intermolecular aromatic π-π interactions in the self-assembly of di-l-phenylalanine (l-Phe-l-Phe, FF), a peptide that is known for hierarchical structure, is well established, the influence of intramolecular π-π interactions on the morphology of the self-assembled structure of FF has not been studied. Herein, the role of intramolecular aromatic π-π interactions is investigated for FF and analogous alanine (Ala)-containing dipeptides, namely, l-Phe-l-Ala (FA) and l-Ala-l-Phe (AF). The results reveal that these dipeptides not only form self-assemblies, but also exhibit remarkable differences in structural morphology. The morphological differences between FF and the analogues indicate the importance of intramolecular π-π interactions, and the structural difference between FA and AF demonstrates the crucial role of the nature of intramolecular side-chain interactions (aromatic-aliphatic or aliphatic-aromatic), in addition to intermolecular interactions, in deciding the final morphology of the self-assembled structure. The current results emphasise that intramolecular aromatic π-π interaction may not be essential to induce self-assembly in smaller peptides, and π (aromatic)-alkyl or alkyl-π (aromatic) interactions may be sufficient. This work also illustrates the versatility of aromatic and a combination of aromatic and aliphatic residues in dipeptides in the formation of structurally diverse self-assembled structures. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Rapid Prototyping of Polymeric Nanopillars by 3D Direct Laser Writing for Controlling Cell Behavior.

PubMed

Buch-Månson, Nina; Spangenberg, Arnaud; Gomez, Laura Piedad Chia; Malval, Jean-Pierre; Soppera, Olivier; Martinez, Karen L

2017-08-23

Mammalian cells have been widely shown to respond to nano- and microtopography that mimics the extracellular matrix. Synthetic nano- and micron-sized structures are therefore of great interest in the field of tissue engineering, where polymers are particularly attractive due to excellent biocompatibility and versatile fabrication methods. Ordered arrays of polymeric pillars provide a controlled topographical environment to study and manipulate cells, but processing methods are typically either optimized for the nano- or microscale. Here, we demonstrate polymeric nanopillar (NP) fabrication using 3D direct laser writing (3D DLW), which offers a rapid prototyping across both size regimes. The NPs are interfaced with NIH3T3 cells and the effect of tuning geometrical parameters of the NP array is investigated. Cells are found to adhere on a wide range of geometries, but the interface depends on NP density and length. The Cell Interface with Nanostructure Arrays (CINA) model is successfully extended to predict the type of interface formed on different NP geometries, which is found to correlate with the efficiency of cell alignment along the NPs. The combination of the CINA model with the highly versatile 3D DLW fabrication thus holds the promise of improved design of polymeric NP arrays for controlling cell growth.

Electrophoretic deposition of thermites onto micro-engineered electrodes prepared by direct-ink writing.

PubMed

Sullivan, K T; Zhu, C; Tanaka, D J; Kuntz, J D; Duoss, E B; Gash, A E

2013-02-14

This work combines electrophoretic deposition (EPD) with direct-ink writing (DIW) to prepare thin films of Al/CuO thermites onto patterned two- and three-dimensional silver electrodes. DIW was used to write the electrodes using a silver nanoparticle ink, and EPD was performed in a subsequent step to deposit the thermite onto the conductive electrodes. Unlike conventional lithographic techniques, DIW is a low-cost and versatile alternative to print fine-featured electrodes, and adds the benefit of printing self-supported three-dimensional structures. EPD provides a method for depositing the composite thermite only onto the conductive electrodes, and with controlled thicknesses, which provides fine spatial and mass control, respectively. EPD has previously been shown to produce well-mixed thermite composites which can pack to reasonably high densities without the need for any postprocessing. Homogeneous mixing is particularly important in reactive composities, where good mixing can enhance the reaction kinetics by decreasing the transport distance between the components. Several two- and three-dimensional designs were investigated to highlight the versatility of using DIW and EPD together. In addition to energetic applications, we anticipate that this combination of techniques will have a variety of other applications, which would benefit from the controlled placement of a thin film of one material onto a conductive architecture of a second material.

Gene expression and morphogenesis during the deposition of Drosophila wing cuticle

PubMed Central

Adler, Paul N.

2017-01-01

ABSTRACT The exoskeleton of insects and other arthropods is a very versatile material that is characterized by a complex multilayer structure. In Sobala and Adler (2016) we analyzed the process of wing cuticle deposition by RNAseq and electron microscopy. In this extra view we discuss the unique aspects of the envelope the first and most outermost layer and the gene expression program seen at the end of cuticle deposition. We discussed the role of undulae in the deposition of cuticle and how the hydrophobicity of wing cuticle arises. PMID:28631994

Gene expression and morphogenesis during the deposition of Drosophila wing cuticle.

PubMed

Adler, Paul N

2017-07-03

The exoskeleton of insects and other arthropods is a very versatile material that is characterized by a complex multilayer structure. In Sobala and Adler (2016) we analyzed the process of wing cuticle deposition by RNAseq and electron microscopy. In this extra view we discuss the unique aspects of the envelope the first and most outermost layer and the gene expression program seen at the end of cuticle deposition. We discussed the role of undulae in the deposition of cuticle and how the hydrophobicity of wing cuticle arises.

Fabrication of SOI structures with buried cavities using Si wafer direct bonding and electrochemical etch-stop

NASA Astrophysics Data System (ADS)

Chung, Gwiy-Sang

2003-10-01

This paper describes the fabrication of SOI structures with buried cavities using SDB and electrochemical etch-stop. These methods are suitable for thick membrane fabrication with accurate thickness, uniformity, and flatness. After a feed-through hole for supplied voltage and buried cavities was formed on a handle Si wafer with p-type, the handle wafer was bonded to an active Si wafer consisting of a p-type substrate with an n-type epitaxial layer corresponding to membrane thickness. The bonded pair was then thinned until electrochemical etch-stop occurred at the pn junction during electrochemical etchback. By using the SDB SOI structure with buried cavities, active membranes, which have a free standing structure with a dimension of 900×900 μm2, were fabricated. It is confirmed that the fabrication process of the SDB SOI structure with buried cavities is a powerful and versatile technology for new MEMS applications.

ADP-ribosyl-N₃: A Versatile Precursor for Divergent Syntheses of ADP-ribosylated Compounds.

PubMed

Li, Lingjun; Li, Qianqian; Ding, Shengqiang; Xin, Pengyang; Zhang, Yuqin; Huang, Shenlong; Zhang, Guisheng

2017-08-14

Adenosine diphosphate-ribose (ADP-ribose) and its derivatives play important roles in a series of complex physiological procedures. The design and synthesis of artificial ADP-ribosylated compounds is an efficient way to develop valuable chemical biology tools and discover new drug candidates. However, the synthesis of ADP-ribosylated compounds is currently difficult due to structural complexity, easily broken pyrophosphate bond and high hydrophilicity. In this paper, ADP-ribosyl-N₃ was designed and synthesized for the first time. With ADP-ribosyl-N₃ as the key precursor, a divergent post-modification strategy was developed to prepare structurally diverse ADP-ribosylated compounds including novel nucleotides and peptides bearing ADP-ribosyl moieties.

Versatile application of indirect Fourier transformation to structure factor analysis: from X-ray diffraction of molecular liquids to small angle scattering of protein solutions.

PubMed

Fukasawa, Toshiko; Sato, Takaaki

2011-02-28

We highlight versatile applicability of a structure-factor indirect Fourier transformation (IFT) technique, hereafter called SQ-IFT. The original IFT aims at the pair distance distribution function, p(r), of colloidal particles from small angle scattering of X-rays (SAXS) and neutrons (SANS), allowing the conversion of the experimental form factor, P(q), into a more intuitive real-space spatial autocorrelation function. Instead, SQ-IFT is an interaction potential model-free approach to the 'effective' or 'experimental' structure factor to yield the pair correlation functions (PCFs), g(r), of colloidal dispersions like globular protein solutions for small-angle scattering data as well as the radial distribution functions (RDFs) of molecular liquids in liquid diffraction (LD) experiments. We show that SQ-IFT yields accurate RDFs of liquid H(2)O and monohydric alcohol reflecting their local intermolecular structures, in which q-weighted structure function, qH(q), conventionally utilized in many LD studies out of necessity of performing direct Fourier transformation, is no longer required. We also show that SQ-IFT applied to theoretically calculated structure factors for uncharged and charged colloidal dispersions almost perfectly reproduces g(r) obtained as a solution of the Ornstein-Zernike (OZ) equation. We further demonstrate the relevance of SQ-IFT in its practical applications, using SANS effective structure factors of lysozyme solutions reported in recent literatures which revealed the equilibrium cluster formation due to coexisting long range electrostatic repulsion and short range attraction between the proteins. Finally, we present SAXS experiments on human serum albumin (HSA) at different ionic strength and protein concentration, in which we discuss the real space picture of spatial distributions of the proteins via the interaction potential model-free route.

Microfluidic magnetic bead conveyor belt.

PubMed

van Pelt, Stijn; Frijns, Arjan; den Toonder, Jaap

2017-11-07

Magnetic beads play an important role in the miniaturization of clinical diagnostics systems. In lab-on-chip platforms, beads can be made to link to a target species and can then be used for the manipulation and detection of this species. Current bead actuation systems utilize complex on-chip coil systems that offer low field strengths and little versatility. We demonstrate a novel system based on an external rotating magnetic field and on-chip soft-magnetic structures to focus the field locally. These structures were designed and optimized using finite element simulations in order to create a number of local flux density maxima. These maxima, to which the magnetic beads are attracted, move over the chip surface in a continuous way together with the rotation of the external field, resulting in a mechanism similar to that of a conveyor belt. A prototype was fabricated using PDMS molding techniques mixed with iron powder for the magnetic structures. In the subsequent experiments, a quadrupole electromagnet was used to create the rotating external field. We observed that beads formed agglomerates that rolled over the chip surface, just above the magnetic structures. Field rotation frequencies between 0.1-50 Hz were tested resulting in magnetic bead speeds of over 1 mm s -1 for the highest frequency. With this, we have shown that our novel concept works, combining a simple design and simple operation with a powerful and versatile method for bead actuation. This makes it a promising method for further research and utilization in lab-on-chip systems.

Minireview: The Role of Nuclear Receptors in Photoreceptor Differentiation and Disease

PubMed Central

Swaroop, Anand

2012-01-01

Rod and cone photoreceptors are specialized sensory cells that mediate vision. Transcriptional controls are critical for the development and long-term survival of photoreceptors; when these controls become ineffective, retinal dysfunction or degenerative disease may result. This review discusses the role of nuclear receptors, a class of ligand-regulated transcription factors, at key stages of photoreceptor life in the mammalian retina. Nuclear receptors with known ligands, such as retinoids or thyroid hormone, together with several orphan receptors without identified physiological ligands, complement other classes of transcription factors in directing the differentiation and functional maintenance of photoreceptors. The potential of nuclear receptors to respond to ligands introduces versatility into the control of photoreceptor development and function and may suggest new opportunities for treatments of photoreceptor disease. PMID:22556342

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

Chen, Chao; Pouransari, Hadi; Rajamanickam, Sivasankaran

We present a parallel hierarchical solver for general sparse linear systems on distributed-memory machines. For large-scale problems, this fully algebraic algorithm is faster and more memory-efficient than sparse direct solvers because it exploits the low-rank structure of fill-in blocks. Depending on the accuracy of low-rank approximations, the hierarchical solver can be used either as a direct solver or as a preconditioner. The parallel algorithm is based on data decomposition and requires only local communication for updating boundary data on every processor. Moreover, the computation-to-communication ratio of the parallel algorithm is approximately the volume-to-surface-area ratio of the subdomain owned by everymore » processor. We also provide various numerical results to demonstrate the versatility and scalability of the parallel algorithm.« less

Versatile simulation testbed for rotorcraft speech I/O system design

NASA Technical Reports Server (NTRS)

Simpson, Carol A.

1986-01-01

A versatile simulation testbed for the design of a rotorcraft speech I/O system is described in detail. The testbed will be used to evaluate alternative implementations of synthesized speech displays and speech recognition controls for the next generation of Army helicopters including the LHX. The message delivery logic is discussed as well as the message structure, the speech recognizer command structure and features, feedback from the recognizer, and random access to controls via speech command.

The intrinsic flexibility of the aptamer targeting the ribosomal protein S8 is a key factor for the molecular recognition.

PubMed

Autiero, Ida; Ruvo, Menotti; Improta, Roberto; Vitagliano, Luigi

2018-04-01

Aptamers are RNA/DNA biomolecules representing an emerging class of protein interactors and regulators. Despite the growing interest in these molecules, current understanding of chemical-physical basis of their target recognition is limited. Recently, the characterization of the aptamer targeting the protein-S8 has suggested that flexibility plays important functional roles. We investigated the structural versatility of the S8-aptamer by molecular dynamics simulations. Five different simulations have been conducted by varying starting structures and temperatures. The simulation of S8-aptamer complex provides a dynamic view of the contacts occurring at the complex interface. The simulation of the aptamer in ligand-free state indicates that its central region is intrinsically endowed with a remarkable flexibility. Nevertheless, none of the trajectory structures adopts the structure observed in the S8-aptamer complex. The aptamer ligand-bound is very rigid in the simulation carried out at 300 K. A structural transition of this state, providing insights into the aptamer-protein recognition process, is observed in a simulation carried out at 400 K. These data indicate that a key event in the binding is linked to the widening of the central region of the aptamer. Particularly relevant is switch of the A26 base from its ligand-free state to a location that allows the G13-C28 base-pairing. Intrinsic flexibility of the aptamer is essential for partner recognition. Present data indicate that S8 recognizes the aptamer through an induced-fit rather than a population-shift mechanism. The present study provides deeper understanding of the structural basis of the structural versatility of aptamers. Copyright © 2018 Elsevier B.V. All rights reserved.

Direct Laser Writing of Single-Material Sheets with Programmable Self-Rolling Capability

NASA Astrophysics Data System (ADS)

Bauhofer, Anton; KröDel, Sebastian; Bilal, Osama; Daraio, Chiara; Constantinescu, Andrei

Direct laser writing, a sub-class of two-photon polymerization, facilitates 3D-printing of single-material microstructures with inherent residual stresses. Here we show that controlled distribution of these stresses allows for fast and cost-effective fabrication of structures with programmable self-rolling capability. We investigate 2D sheets that evolve into versatile 3D structures. Precise control over the shape morphing potential is acquired through variations in geometry and writing parameters. Effects of capillary action and gravity were shown to be relevant for very thin sheets (thickness <1.5um) and have been analytically and experimentally quantified. In contrast to that, the deformations of sheets with larger thickness (>1.5um) are dominated by residual stresses and adhesion forces. The presented structures create local tensions up to 180MPa, causing rolling curvatures of 25E3m-1. A comprehensive analytical model that captures the relevant influence factors was developed based on laminate plate theory. The predicted curvature and directionality correspond well with the experimentally obtained data. Potential applications are found in drug encapsulation and particle traps for emulsions with differing surface energies. This work was supported by the Swiss National Science Foundation.

Length scale selects directionality of droplets on vibrating pillar ratchet

DOE PAGES

Agapov, Rebecca L.; Boreyko, Jonathan B.; Briggs, Dayrl P.; ...

2014-09-22

Directional control of droplet motion at room temperature is of interest for applications such as microfluidic devices, self-cleaning coatings, and directional adhesives. Here, arrays of tilted pillars ranging in height from the nanoscale to the microscale are used as structural ratchets to directionally transport water at room temperature. Water droplets deposited on vibrating chips with a nanostructured ratchet move preferentially in the direction of the feature tilt while the opposite directionality is observed in the case of microstructured ratchets. This remarkable switch in directionality is consistent with changes in the contact angle hysteresis. To glean further insights into the lengthmore » scale dependent asymmetric contact angle hysteresis, the contact lines formed by a nonvolatile room temperature ionic liquid placed onto the tilted pillar arrays were visualized and analyzed in situ in a scanning electron microscope. As a result, the ability to tune droplet directionality by merely changing the length scale of surface features all etched at the same tilt angle would be a versatile tool for manipulating multiphase flows and for selecting droplet directionality in other lap-on-chip applications.« less

Covalent Bonding of Thermoplastics to Rubbers for Printable, Reel-to-Reel Processing in Soft Robotics and Microfluidics.

PubMed

Taylor, Jay M; Perez-Toralla, Karla; Aispuro, Ruby; Morin, Stephen A

2018-02-01

The lamination of mechanically stiff structures to elastic materials is prevalent in biological systems and popular in many emerging synthetic systems, such as soft robotics, microfluidics, stretchable electronics, and pop-up assemblies. The disparate mechanical and chemical properties of these materials have made it challenging to develop universal synthetic procedures capable of reliably adhering to these classes of materials together. Herein, a simple and scalable procedure is described that is capable of covalently laminating a variety of commodity ("off-the-shelf") thermoplastic sheets to silicone rubber films. When combined with laser printing, the nonbonding sites can be "printed" onto the thermoplastic sheets, enabling the direct fabrication of microfluidic systems for actuation and liquid handling applications. The versatility of this approach in generating thin, multifunctional laminates is demonstrated through the fabrication of milliscale soft actuators and grippers with hinged articulation and microfluidic channels with built-in optical filtering and pressure-dependent geometries. This method of fabrication offers several advantages, including technical simplicity, process scalability, design versatility, and material diversity. The concepts and strategies presented herein are broadly applicable to the soft robotics, microfluidics, and advanced and additive manufacturing communities where hybrid rubber/plastic structures are prevalent. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Understanding the roles of nonstructural carbohydrates in forest trees - from what we can measure to what we want to know.

PubMed

Hartmann, Henrik; Trumbore, Susan

2016-07-01

Contents 386 I. 386 II. 388 III. 392 IV. 392 V. 396 VI. 399 399 References 399 SUMMARY: Carbohydrates provide the building blocks for plant structures as well as versatile resources for metabolic processes. The nonstructural carbohydrates (NSC), mainly sugars and starch, fulfil distinct functional roles, including transport, energy metabolism and osmoregulation, and provide substrates for the synthesis of defence compounds or exchange with symbionts involved in nutrient acquisition or defence. At the whole-plant level, NSC storage buffers the asynchrony of supply and demand on diel, seasonal or decadal temporal scales and across plant organs. Despite its central role in plant function and in stand-level carbon cycling, our understanding of storage dynamics, its controls and response to environmental stresses is very limited, even after a century of research. This reflects the fact that often storage is defined by what we can measure, that is, NSC concentrations, and the interpretation of these as a proxy for a single function, storage, rather than the outcome of a range of NSC source and sink functions. New isotopic tools allow direct quantification of timescales involved in NSC dynamics, and show that NSC-C fixed years to decades previously is used to support tree functions. Here we review recent advances, with emphasis on the context of the interactions between NSC, drought and tree mortality. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

New paradigm in ankyrin repeats: Beyond protein-protein interaction module.

PubMed

Islam, Zeyaul; Nagampalli, Raghavendra Sashi Krishna; Fatima, Munazza Tamkeen; Ashraf, Ghulam Md

2018-04-01

Classically, ankyrin repeat (ANK) proteins are built from tandems of two or more repeats and form curved solenoid structures that are associated with protein-protein interactions. These are short, widespread structural motif of around 33 amino acids repeats in tandem, having a canonical helix-loop-helix fold, found individually or in combination with other domains. The multiplicity of structural pattern enables it to form assemblies of diverse sizes, required for their abilities to confer multiple binding and structural roles of proteins. Three-dimensional structures of these repeats determined to date reveal a degree of structural variability that translates into the considerable functional versatility of this protein superfamily. Recent work on the ANK has proposed novel structural information, especially protein-lipid, protein-sugar and protein-protein interaction. Self-assembly of these repeats was also shown to prevent the associated protein in forming filaments. In this review, we summarize the latest findings and how the new structural information has increased our understanding of the structural determinants of ANK proteins. We discussed latest findings on how these proteins participate in various interactions to diversify the ANK roles in numerous biological processes, and explored the emerging and evolving field of designer ankyrins and its framework for protein engineering emphasizing on biotechnological applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Development and applications of two computational procedures for determining the vibration modes of structural systems. [aircraft structures - aerospaceplanes

NASA Technical Reports Server (NTRS)

Kvaternik, R. G.

1975-01-01

Two computational procedures for analyzing complex structural systems for their natural modes and frequencies of vibration are presented. Both procedures are based on a substructures methodology and both employ the finite-element stiffness method to model the constituent substructures. The first procedure is a direct method based on solving the eigenvalue problem associated with a finite-element representation of the complete structure. The second procedure is a component-mode synthesis scheme in which the vibration modes of the complete structure are synthesized from modes of substructures into which the structure is divided. The analytical basis of the methods contains a combination of features which enhance the generality of the procedures. The computational procedures exhibit a unique utilitarian character with respect to the versatility, computational convenience, and ease of computer implementation. The computational procedures were implemented in two special-purpose computer programs. The results of the application of these programs to several structural configurations are shown and comparisons are made with experiment.

Characterization of molecular associations involving L-ornithine and α-ketoglutaric acid: crystal structure of L-ornithinium α-ketoglutarate.

PubMed

Allouchi, H; Céolin, R; Berthon, L; Tombret, F; Rietveld, I B

2014-07-01

The crystal structure of L-ornithinium α-ketoglutarate (C5H13N2O2, C5H5O5) has been solved by direct methods using single crystal X-ray diffraction data. It crystallizes in the monoclinic system, space group P21, unit cell parameters a=15.4326(3), b=5.2015(1), c=16.2067(3) Å and β=91.986(1)°, containing two independent pairs of molecular ions in the asymmetric unit. An extensive hydrogen-bond network and electrostatic charges due to proton transfer provide an important part of the cohesive energy of the crystal. The conformational versatility of L-ornithine and α-ketoglutaric acid is illustrated by the present results and crystal structures available from the Cambridge Structural Database. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Lithium: a versatile tool for understanding renal physiology

PubMed Central

Ecelbarger, Carolyn M.

2013-01-01

By virtue of its unique interactions with kidney cells, lithium became an important research tool in renal physiology and pathophysiology. Investigators have uncovered the intricate relationships of lithium with the vasopressin and aldosterone systems, and the membrane channels or transporters regulated by them. While doing so, their work has also led to 1) questioning the role of adenylyl cyclase activity and prostaglandins in lithium-induced suppression of aquaporin-2 gene transcription; 2) unraveling the role of purinergic signaling in lithium-induced polyuria; and 3) highlighting the importance of the epithelial sodium channel (ENaC) in lithium-induced nephrogenic diabetes insipidus (NDI). Lithium-induced remodeling of the collecting duct has the potential to shed new light on collecting duct remodeling in disease conditions, such as diabetes insipidus. The finding that lithium inhibits glycogen synthase kinase-3β (GSK3β) has opened an avenue for studies on the role of GSK3β in urinary concentration, and GSK isoforms in renal development. Finally, proteomic and metabolomic profiling of the kidney and urine in rats treated with lithium is providing insights into how the kidney adapts its metabolism in conditions such as acquired NDI and the multifactorial nature of lithium-induced NDI. This review provides state-of-the-art knowledge of lithium as a versatile tool for understanding the molecular physiology of the kidney, and a comprehensive view of how this tool is challenging some of our long-standing concepts in renal physiology, often with paradigm shifts, and presenting paradoxical situations in renal pathophysiology. In addition, this review points to future directions in research where lithium can lead the renal community. PMID:23408166

Freeze-Casting of Porous Biomaterials: Structure, Properties and Opportunities

PubMed Central

Deville, Sylvain

2010-01-01

The freeze-casting of porous materials has received a great deal of attention during the past few years. This simple process, where a material suspension is simply frozen and then sublimated, provides materials with unique porous architectures, where the porosity is almost a direct replica of the frozen solvent crystals. This review focuses on the recent results on the process and the derived porous structures with regards to the biomaterials applications. Of particular interest is the architecture of the materials and the versatility of the process, which can be readily controlled and applied to biomaterials applications. A careful control of the starting formulation and processing conditions is required to control the integrity of the structure and resulting properties. Further in vitro and in vivo investigations are required to validate the potential of this new class of porous materials.

Versatile platform for nanotechnology based on circular permutations of chaperonin protein

NASA Technical Reports Server (NTRS)

McMillan, R. Andrew (Inventor); Kagawa, Hiromi (Inventor); Paavola, Chad D. (Inventor); Chan, Suzanne L. (Inventor); Li, Yi-Fen (Inventor); Trent, Jonathan D. (Inventor)

2010-01-01

The present invention provides chaperonin polypeptides which are modified to include N-terminal and C-terminal ends that are relocated from the central pore region to various different positions in the polypeptide which are located on the exterior of the folded modified chaperonin polypeptide. In the modified chaperonin polypeptide, the naturally-occurring N-terminal and C-terminal ends are joined together directly or with an intervening linker peptide sequence. The relocated N-terminal or C-terminal ends can be covalently joined to, or bound with another molecule such as a nucleic acid molecule, a lipid, a carbohydrate, a second polypeptide, or a nanoparticle. The modified chaperonin polypeptides can assemble into double-ringed chaperonin structures. Further, the chaperonin structures can organize into higher order structures such as nanofilaments or nanoarrays which can be used to produce nanodevices and nanocoatings.

Doped graphene supercapacitors.

PubMed

Kumar, Nanjundan Ashok; Baek, Jong-Beom

2015-12-11

Heteroatom-doped graphitic frameworks have received great attention in energy research, since doping endows graphitic structures with a wide spectrum of properties, especially critical for electrochemical supercapacitors, which tend to complement or compete with the current lithium-ion battery technology/devices. This article reviews the latest developments in the chemical modification/doping strategies of graphene and highlights the versatility of such heteroatom-doped graphitic structures. Their role as supercapacitor electrodes is discussed in detail. This review is specifically focused on the concept of material synthesis, techniques for electrode fabrication and metrics of performance, predominantly covering the last four years. Challenges and insights into the future research and perspectives on the development of novel electrode architectures for electrochemical supercapacitors based on doped graphene are also discussed.

Doped graphene supercapacitors

NASA Astrophysics Data System (ADS)

Ashok Kumar, Nanjundan; Baek, Jong-Beom

2015-12-01

Heteroatom-doped graphitic frameworks have received great attention in energy research, since doping endows graphitic structures with a wide spectrum of properties, especially critical for electrochemical supercapacitors, which tend to complement or compete with the current lithium-ion battery technology/devices. This article reviews the latest developments in the chemical modification/doping strategies of graphene and highlights the versatility of such heteroatom-doped graphitic structures. Their role as supercapacitor electrodes is discussed in detail. This review is specifically focused on the concept of material synthesis, techniques for electrode fabrication and metrics of performance, predominantly covering the last four years. Challenges and insights into the future research and perspectives on the development of novel electrode architectures for electrochemical supercapacitors based on doped graphene are also discussed.

Exploring the difference in xerogels and organogels through in situ observation

PubMed Central

Li, Zhiming; Wang, Haitao; Li, Min; Ozaki, Yukihiro; Wei, Jue

2018-01-01

Solvent–gelator interactions play a key role in mediating organogel formation and ultimately determine the physico-chemical properties of the organogels and xerogels. The ethanol organogels of 1,4-bis[(3,4,5-trihexyloxy phenyl)hydrazide]phenylene (TC6) were investigated in situ by FT-IR, Raman and fluorescence spectra, and XRD, and it was confirmed that the intermolecular interaction and aggregation structure of TC6 ethanol organogels were quite different from those of xerogels. Simultaneously, unprecedented phase transition from organogel to suspension upon heating was observed in ethanol organogel, and the suspension phase exhibited lytropic liquid crystalline behaviour with a rectangular columnar structure. This study may open the possibility to design new gelators with a new dimension of versatility. PMID:29410792

Block copolymer self-assembly–directed synthesis of mesoporous gyroidal superconductors

PubMed Central

Robbins, Spencer W.; Beaucage, Peter A.; Sai, Hiroaki; Tan, Kwan Wee; Werner, Jörg G.; Sethna, James P.; DiSalvo, Francis J.; Gruner, Sol M.; Van Dover, Robert B.; Wiesner, Ulrich

2016-01-01

Superconductors with periodically ordered mesoporous structures are expected to have properties very different from those of their bulk counterparts. Systematic studies of such phenomena to date are sparse, however, because of a lack of versatile synthetic approaches to such materials. We demonstrate the formation of three-dimensionally continuous gyroidal mesoporous niobium nitride (NbN) superconductors from chiral ABC triblock terpolymer self-assembly–directed sol-gel–derived niobium oxide with subsequent thermal processing in air and ammonia gas. Superconducting materials exhibit a critical temperature (Tc) of about 7 to 8 K, a flux exclusion of about 5% compared to a dense NbN solid, and an estimated critical current density (Jc) of 440 A cm−2 at 100 Oe and 2.5 K. We expect block copolymer self-assembly–directed mesoporous superconductors to provide interesting subjects for mesostructure-superconductivity correlation studies. PMID:27152327

Block copolymer self-assembly-directed synthesis of mesoporous gyroidal superconductors.

PubMed

Robbins, Spencer W; Beaucage, Peter A; Sai, Hiroaki; Tan, Kwan Wee; Werner, Jörg G; Sethna, James P; DiSalvo, Francis J; Gruner, Sol M; Van Dover, Robert B; Wiesner, Ulrich

2016-01-01

Superconductors with periodically ordered mesoporous structures are expected to have properties very different from those of their bulk counterparts. Systematic studies of such phenomena to date are sparse, however, because of a lack of versatile synthetic approaches to such materials. We demonstrate the formation of three-dimensionally continuous gyroidal mesoporous niobium nitride (NbN) superconductors from chiral ABC triblock terpolymer self-assembly-directed sol-gel-derived niobium oxide with subsequent thermal processing in air and ammonia gas. Superconducting materials exhibit a critical temperature (T c) of about 7 to 8 K, a flux exclusion of about 5% compared to a dense NbN solid, and an estimated critical current density (J c) of 440 A cm(-2) at 100 Oe and 2.5 K. We expect block copolymer self-assembly-directed mesoporous superconductors to provide interesting subjects for mesostructure-superconductivity correlation studies.

Toward all-carbon electronics: fabrication of graphene-based flexible electronic circuits and memory cards using maskless laser direct writing.

PubMed

Liang, Jiajie; Chen, Yongsheng; Xu, Yanfei; Liu, Zhibo; Zhang, Long; Zhao, Xin; Zhang, Xiaoliang; Tian, Jianguo; Huang, Yi; Ma, Yanfeng; Li, Feifei

2010-11-01

Owing to its extraordinary electronic property, chemical stability, and unique two-dimensional nanostructure, graphene is being considered as an ideal material for the highly expected all-carbon-based micro/nanoscale electronics. Herein, we present a simple yet versatile approach to constructing all-carbon micro/nanoelectronics using solution-processing graphene films directly. From these graphene films, various graphene-based microcosmic patterns and structures have been fabricated using maskless computer-controlled laser cutting. Furthermore, a complete system involving a prototype of a flexible write-once-read-many-times memory card and a fast data-reading system has been demonstrated, with infinite data retention time and high reliability. These results indicate that graphene could be the ideal material for fabricating the highly demanded all-carbon and flexible devices and electronics using the simple and efficient roll-to-roll printing process when combined with maskless direct data writing.

Form and function in gene regulatory networks: the structure of network motifs determines fundamental properties of their dynamical state space.

PubMed

Ahnert, S E; Fink, T M A

2016-07-01

Network motifs have been studied extensively over the past decade, and certain motifs, such as the feed-forward loop, play an important role in regulatory networks. Recent studies have used Boolean network motifs to explore the link between form and function in gene regulatory networks and have found that the structure of a motif does not strongly determine its function, if this is defined in terms of the gene expression patterns the motif can produce. Here, we offer a different, higher-level definition of the 'function' of a motif, in terms of two fundamental properties of its dynamical state space as a Boolean network. One is the basin entropy, which is a complexity measure of the dynamics of Boolean networks. The other is the diversity of cyclic attractor lengths that a given motif can produce. Using these two measures, we examine all 104 topologically distinct three-node motifs and show that the structural properties of a motif, such as the presence of feedback loops and feed-forward loops, predict fundamental characteristics of its dynamical state space, which in turn determine aspects of its functional versatility. We also show that these higher-level properties have a direct bearing on real regulatory networks, as both basin entropy and cycle length diversity show a close correspondence with the prevalence, in neural and genetic regulatory networks, of the 13 connected motifs without self-interactions that have been studied extensively in the literature. © 2016 The Authors.

Femtosecond laser processing of optical fibres for novel sensor development

NASA Astrophysics Data System (ADS)

Kalli, Kyriacos; Theodosiou, Antreas; Ioannou, Andreas; Lacraz, Amedee

2017-04-01

We present results of recent research where we have utilized a femtosecond laser to micro-structure silica and polymer optical fibres in order to realize versatile optical components such as diffractive optical elements on the fibre end face, the inscription of integrated waveguide circuits in the fibre cladding and novel optical fibre sensors designs based on Bragg gratings in the core. A major hurdle in tailoring or modifying the properties of optical fibres is the development of an inscription method that can prove to be a flexible and reliable process that is generally applicable to all optical fibre types; this requires careful matching of the laser parameters and optics in order to examine the spatial limits of direct laser writing, whether the application is structuring at the surface of the optical fibre or inscription in the core and cladding of the fibre. We demonstrate a variety of optical components such as two-dimensional grating structures, Bessel, Airy and vortex beam generators; moreover, optical bridging waveguides inscribed in the cladding of single-mode fibre as a means to selectively couple light from single-core to multi-core optical fibres, and demonstrate a grating based sensor; finally, we have developed a novel femtosecond laser inscription method for the precise inscription of tailored Bragg grating sensors in silica and polymer optical fibres. We also show that this novel fibre Bragg grating inscription technique can be used to modify and add versatility to an existing, encapsulated optical fibre pressure sensor.

Directed evolution: tailoring biocatalysts for industrial applications.

PubMed

Kumar, Ashwani; Singh, Suren

2013-12-01

Current challenges and promises of white biotechnology encourage protein engineers to use a directed evolution approach to generate novel and useful biocatalysts for various sets of applications. Different methods of enzyme engineering have been used in the past in an attempt to produce enzymes with improved functions and properties. Recent advancement in the field of random mutagenesis, screening, selection and computational design increased the versatility and the rapid development of enzymes under strong selection pressure with directed evolution experiments. Techniques of directed evolution improve enzymes fitness without understanding them in great detail and clearly demonstrate its future role in adapting enzymes for use in industry. Despite significant advances to date regarding biocatalyst improvement, there still remains a need to improve mutagenesis strategies and development of easy screening and selection tools without significant human intervention. This review covers fundamental and major development of directed evolution techniques, and highlights the advances in mutagenesis, screening and selection methods with examples of enzymes developed by using these approaches. Several commonly used methods for creating molecular diversity with their advantages and disadvantages including some recently used strategies are also discussed.

Osteoblast and osteocyte: games without frontiers.

PubMed

Capulli, Mattia; Paone, Riccardo; Rucci, Nadia

2014-11-01

The portrait of osteoblasts and osteocytes has been subjected to a revision, since a large body of evidence is attributing these cells amazing roles both inside and outside the bone. The osteoblast, long confined to its bone building function, is actually a very eclectic cell, actively regulating osteoclast formation and function as well as hematopoietic stem cells homeostasis. It is also an endocrine cell, affecting energy metabolism, male fertility and cognition through the release of osteocalcin, a perfect definition-fitting hormone in its uncarboxylated state. As for the osteocytes, many evidence shows that they do not merely represent the final destination of the osteoblasts, but they are instead very active cells that, besides a mechanosensorial function, actively contribute to the bone remodelling by regulating bone formation and resorption. The regulation is exerted by the production of sclerostin (SOST), which in turn inhibits osteoblast differentiation by blocking Wnt/beta-catenin pathway. At the same time, osteocytes influence bone resorption both indirectly, by producing RANKL, which stimulates osteoclastogenesis, and directly by means of a local osteolysis, which is observed especially under pathological conditions. The great versatility of both these cells reflects the complexity of the bone tissue, which has not only a structural role, but influences and is influenced by different organs, taking part in homeostatic and adaptive responses affecting the whole organism. Copyright © 2014. Published by Elsevier Inc.

Novel spider-web-like nanoporous networks based on jute cellulose nanowhiskers.

PubMed

Cao, Xinwang; Wang, Xianfeng; Ding, Bin; Yu, Jianyong; Sun, Gang

2013-02-15

Cellulose nanowhiskers as a kind of renewable and biocompatible nanomaterials evoke much interest because of its versatility in various applications. Herein, for the first time, a novel controllable fabrication of spider-web-like nanoporous networks based on jute cellulose nanowhiskers (JCNs) deposited on the electrospun (ES) nanofibrous membrane by simple directly immersion-drying method is reported. Jute cellulose nanowhiskers were extracted from jute fibers with a high yield (over 80%) via a 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)/NaBr/NaClO system selective oxidization combined with mechanical homogenization. The morphology of JCNs nanoporous networks/ES nanofibrous membrane architecture, including coverage rate, pore-width and layer-by-layer packing structure of the nanoporous networks, can be finely controlled by regulating the JCNs dispersions properties and drying conditions. The versatile nanoporous network composites based on jute cellulose nanowhiskers with ultrathin diameters (3-10 nm) and nanofibrous membrane supports with diameters of 100-300 nm, would be particularly useful for filter applications. Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.

Advanced texture filtering: a versatile framework for reconstructing multi-dimensional image data on heterogeneous architectures

NASA Astrophysics Data System (ADS)

Zellmann, Stefan; Percan, Yvonne; Lang, Ulrich

2015-01-01

Reconstruction of 2-d image primitives or of 3-d volumetric primitives is one of the most common operations performed by the rendering components of modern visualization systems. Because this operation is often aided by GPUs, reconstruction is typically restricted to first-order interpolation. With the advent of in situ visualization, the assumption that rendering algorithms are in general executed on GPUs is however no longer adequate. We thus propose a framework that provides versatile texture filtering capabilities: up to third-order reconstruction using various types of cubic filtering and interpolation primitives; cache-optimized algorithms that integrate seamlessly with GPGPU rendering or with software rendering that was optimized for cache-friendly "Structure of Array" (SoA) access patterns; a memory management layer (MML) that gracefully hides the complexities of extra data copies necessary for memory access optimizations such as swizzling, for rendering on GPGPUs, or for reconstruction schemes that rely on pre-filtered data arrays. We prove the effectiveness of our software architecture by integrating it into and validating it using the open source direct volume rendering (DVR) software DeskVOX.

A versatile single molecular precursor for the synthesis of layered oxide cathode materials for Li-ion batteries.

PubMed

Li, Maofan; Liu, Jiajie; Liu, Tongchao; Zhang, Mingjian; Pan, Feng

2018-02-01

A carbonyl-bridged single molecular precursor LiTM(acac) 3 [transition metal (TM) = cobalt/manganese/nickel (Co/Mn/Ni), acac = acetylacetone], featuring a one-dimensional chain structure, was designed and applied to achieve the layered oxide cathode materials: LiTMO 2 (TM = Ni/Mn/Co, NMC). As examples, layered oxides, primary LiCoO 2 , binary LiNi 0.8 Co 0.2 O 2 and ternary LiNi 0.5 Mn 0.3 Co 0.2 O 2 were successfully prepared to be used as cathode materials. When they are applied to lithium-ion batteries (LIBs), all exhibit good electrochemical performance because of their unique morphology and great uniformity of element distribution. This versatile precursor is predicted to accommodate many other metal cations, such as aluminum (Al 3+ ), iron (Fe 2+ ), and sodium (Na + ), because of the flexibility of organic ligand, which not only facilitates the doping-modification of the NMC system, but also enables synthesis of Na-ion layered oxides. This opens a new direction of research for the synthesis of high-performance layered oxide cathode materials for LIBs.

Diversity and specificity: auxin perception and signaling through the TIR1/AFB pathway

DOE PAGES

Wang, Renhou; Estelle, Mark

2014-07-15

Auxin is a versatile plant hormone that plays an essential role in most aspects of plant growth and development. Auxin regulates various growth processes by modulating gene transcription through a SCF TIR1/AFB-Aux/IAA-ARF nuclear signaling module. Recent work has generated clues as to how multiple layers of regulation of the auxin signaling components may result in diverse and specific response outputs. Finally, in particular, interaction and structural studies of key auxin signaling proteins have produced novel insights into the molecular basis of auxin-regulated transcription and may lead to a refined auxin signaling model.

Unusual flavoenzyme catalysis in marine bacteria

PubMed Central

Teufel, Robin; Agarwal, Vinayak; Moore, Bradley S.

2016-01-01

Ever since the discovery of the flavin cofactor more than 80 years ago, flavin-dependent enzymes have emerged as ubiquitous and versatile redox catalysts in primary metabolism. Yet, the recent advances in the discovery and characterization of secondary metabolic pathways exposed new roles for flavin-mediated catalysis in the generation of structurally complex natural products. Here, we review a selection of key biosynthetic flavoenzymes from marine bacterial secondary metabolism and illustrate how their functional and mechanistic investigation expanded our view of the cofactor's chemical repertoire and led to the discovery of a previously unknown flavin redox state. PMID:26803009

Fiber and fabric solar cells by directly weaving carbon nanotube yarns with CdSe nanowire-based electrodes

NASA Astrophysics Data System (ADS)

Zhang, Luhui; Shi, Enzheng; Ji, Chunyan; Li, Zhen; Li, Peixu; Shang, Yuanyuan; Li, Yibin; Wei, Jinquan; Wang, Kunlin; Zhu, Hongwei; Wu, Dehai; Cao, Anyuan

2012-07-01

Electrode materials are key components for fiber solar cells, and when combined with active layers (for light absorption and charge generation) in appropriate ways, they enable design and fabrication of efficient and innovative device structures. Here, we apply carbon nanotube yarns as counter electrodes in combination with CdSe nanowire-grafted primary electrodes (Ti wire) for making fiber and fabric-shaped photoelectrochemical cells with power conversion efficiencies in the range 1% to 2.9%. The spun-twist long nanotube yarns possess both good electrical conductivity and mechanical flexibility compared to conventional metal wires or carbon fibers, which facilitate fabrication of solar cells with versatile configurations. A unique feature of our process is that instead of making individual fiber cells, we directly weave single or multiple nanotube yarns with primary electrodes into a functional fabric. Our results demonstrate promising applications of semiconducting nanowires and carbon nanotubes in woven photovoltaics.Electrode materials are key components for fiber solar cells, and when combined with active layers (for light absorption and charge generation) in appropriate ways, they enable design and fabrication of efficient and innovative device structures. Here, we apply carbon nanotube yarns as counter electrodes in combination with CdSe nanowire-grafted primary electrodes (Ti wire) for making fiber and fabric-shaped photoelectrochemical cells with power conversion efficiencies in the range 1% to 2.9%. The spun-twist long nanotube yarns possess both good electrical conductivity and mechanical flexibility compared to conventional metal wires or carbon fibers, which facilitate fabrication of solar cells with versatile configurations. A unique feature of our process is that instead of making individual fiber cells, we directly weave single or multiple nanotube yarns with primary electrodes into a functional fabric. Our results demonstrate promising applications of semiconducting nanowires and carbon nanotubes in woven photovoltaics. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr31440a

DNA nanostructure-directed assembly of metal nanoparticle superlattices

NASA Astrophysics Data System (ADS)

Julin, Sofia; Nummelin, Sami; Kostiainen, Mauri A.; Linko, Veikko

2018-05-01

Structural DNA nanotechnology provides unique, well-controlled, versatile, and highly addressable motifs and templates for assembling materials at the nanoscale. These methods to build from the bottom-up using DNA as a construction material are based on programmable and fully predictable Watson-Crick base pairing. Researchers have adopted these techniques to an increasing extent for creating numerous DNA nanostructures for a variety of uses ranging from nanoelectronics to drug-delivery applications. Recently, an increasing effort has been put into attaching nanoparticles (the size range of 1-20 nm) to the accurate DNA motifs and into creating metallic nanostructures (typically 20-100 nm) using designer DNA nanoshapes as molds or stencils. By combining nanoparticles with the superior addressability of DNA-based scaffolds, it is possible to form well-ordered materials with intriguing and completely new optical, plasmonic, electronic, and magnetic properties. This focused review discusses the DNA structure-directed nanoparticle assemblies covering the wide range of different one-, two-, and three-dimensional systems.

Directing self-assembly of gold nanoparticles in diblock copolymer scaffold

NASA Astrophysics Data System (ADS)

Li, Qifang; He, Jinbo; Glogowski, Elizabeth; Emrick, Todd; Russell, Thomas

2007-03-01

A versatile hierarchical approach for directing self -assembly of gold nanostructures with size 2-3nm in diblock copolymer scaffolds is found. Diblock copolymer polystyrene-b-poly(2-vinylpyridine) (PS-b-P2VP) is used to form a regular scaffold of highly anisotropic, stripe-like domains, and controlled differential wetting by dichloromethane and thermal annealing guides gold nanoparticles with half hydrophilic ligand to aggregate selectively along the scaffold, producing highly organized metal nanostructures. In as-cast block-copolymer and gold nanoparticles thin films, micelle structure and gold nanoparticles random distribution on scaffold are typically observed. However, samples annealed in dichloromethane exhibit well-defined short-range ordered nanostructure with gold nanoparticles located at the interface of PS and P2VP nanoscale domain. After annealing at 170 C, the gold nanoparticles at interface migrated into the middle of P2VP phase and exhibited long-range ordered hierarchical structures. Synergistic interactions between the gold nanoparticles and the PS-b-P2VP caused an orientation of the microdomains normal to the film surface.

Surface tension driven aggregation of organic nanowires via lab in a droplet.

PubMed

Gu, Jianmin; Yin, Baipeng; Fu, Shaoyan; Feng, Man; Zhang, Ziming; Dong, Haiyun; Gao, Faming; Zhao, Yong Sheng

2018-06-05

Directing the architecture of complex organic nanostructures is desirable and still remains a challenge in areas of materials science due to their structure-dependent collective optoelectronic properties. Herein, we demonstrate a simple and versatile solution strategy that allows surface tension to drive low-dimensional nanostructures to aggregate into complex structures via a lab in a droplet technique. By selecting a suitable combination of a solvent and an anti-solvent with controllable surface tension difference, the droplets can be automatically cracked into micro-droplets, which provides an aggregation force directed toward the centre of the droplet to drive the low-dimensional building blocks to form the special aggregations during the self-assembly process. This synthetic strategy has been shown to be universal for organic materials, which is beneficial for further optimizing the optoelectronic properties. These results contribute to gaining an insightful understanding on the detailed growth mechanism of complex organic nanostructures and greatly promoting the development of organic nanophotonics.

Structure-Directed and Tailored Diversity Synthetic Antibody Libraries Yield Novel Anti-EGFR Antagonists.

PubMed

Miersch, Shane; Maruthachalam, Bharathikumar Vellalore; Geyer, C Ronald; Sidhu, Sachdev S

2017-05-19

We tested whether grafting an interaction domain into the hypervariable loop of a combinatorial antibody library could promote targeting to a specific epitope. Formation of the epidermal growth factor receptor (EGFR) signaling heterodimer involves extensive contacts mediated by a "dimerization loop." We grafted the dimerization loop into the third hypervariable loop of a synthetic antigen-binding fragment (Fab) library and diversified other loops using a tailored diversity strategy. This structure-directed Fab library and a naı̈ve synthetic Fab library were used to select Fabs against EGFR. Both libraries yielded high affinity Fabs that bound to overlapping epitopes on cell-surface EGFR, inhibited receptor activation, and targeted epitopes distinct from those of cetuximab and panitumumab. Epitope mapping experiments revealed complex sites of interaction, comprised of domains I and II but not exclusively localized to the receptor dimerization loop. These results validate the grafting approach for designing Fab libraries and also underscore the versatility of naı̈ve synthetic libraries.

A Facile Growth of Cu2ZnSnS4/ZnS Materials by Sulfurization of Stacked Co-Electroplated-Annealed Metallic Film(s) for Photovoltaic Applications

NASA Astrophysics Data System (ADS)

Turkdogan, Sunay

2018-04-01

In this paper, growth and characterization of functional Cu2ZnSnS4 (CZTS) and ZnS materials are demonstrated. We propose a versatile growth method that depends on the deposition of stacked metallic film by electroplating followed by sulfurization in Sulfur ambient at 500 °C. We have investigated the effect of direct and indirect sulfurization methods ZnS materials were grown as a proof of concept material to make the comparison between two methods. Indirect sulfurization was found to produce higher quality materials and therefore used for CZTS material growth, as well. The results show that CZTS and ZnS materials were grown with high crystal quality in wurtzite and zincblende structure form, respectively. CZTS materials have ∼1.49 eV direct-band gap energy, hydrophilic surface and possess p-type conductivity. All the results are in good agreement with the literature and we believe that our versatile growth method is superior to most of vacuum and non-vacuum based growth methods when the large-scale production and low-cost fabrication are of particular interests. The developed method might not only be promising to grow CZTS and ZnS, but also other semiconductors that can be employed for various optoelectronic/electronic devices.

Directed Self-Organization of Polymer-Grafted Nanoparticles in Polymer Thin Films

NASA Astrophysics Data System (ADS)

Zhang, Ren

The controlled organization of nanoparticle (NP) constituents into superstructures of well-defined shape, composition and connectivity represents a continuing challenge in the development of novel hybrid materials for many technological applications. Surface modification of NPs with grafted polymer ligands has emerged as a versatile means to control the interaction and organization of particle constituents in polymer-matrix composite materials. In this study, by incorporating polymer-grafted nanoparticles (PGNPs) into polymeric thin films, we aim to understand and control the spatial organization of PGNPs through the interactions between polymer brush layer and matrix chains. As model systems, we investigate thermodynamic behaviors of polystyrene-tethered gold nanoparticles (denoted as AuPS) dispersed in polymer thin film matrices with identical and different chemical compositions (PS and PMMA, respectively), and evaluate the influence of external perturbation fields on directed organization of nanofillers. With the presence of unfavorable enthalpic interactions between grafted and free polymer chains (i.e. AuPS/ PMMA blend thin films), phase-separated structures are generated upon thermal annealing, characterized with morphologies ranging from discrete droplets to spinodal structures, which is consistent with composition-dependent classic binary polymer blends phase separation. The phase separation kinetics of AuPS/ PMMA blends exhibit distinct features compared to the parent PS/ PMMA homopolymer blends. We further illustrate phase-separated AuPS-rich domains can be directed into unidirectionally aligned anisotropic structures through soft-shear dynamic zone annealing (DZA-SS) process with tunable domain aspect ratios. To exert exquisite control over the shape, size and location of phase-separated PGNP domains, topographically patterned elastomer confinement is introduced to PGNP/ polymer blend thin films during thermal annealing. When the phase-separated lengthscale coincides with confined pattern dimension, long-range ordered submicron-sized AuPS domains are generated in PMMA matrices with dense and well-dispersed nanoparticle distribution. Furthermore, preferential segregation of AuPS nanoparticles at patterned mesa regions can be induced in PS matrices where enthalpic interactions are absent. This selective segregation is achieved due to the local perturbation of grafted chains when confined in a restricted space. The efficiency of this particle segregation process within patterned mesa-trench films can be tuned by changing the relative entropic confinement effects on grafted and matrix chains. This physical pattern directed PGNP organization strategy is applicable to versatile pattern geometries and nanoparticle compositions.

Mechanically enhanced nested-network hydrogels as a coating material for biomedical devices.

PubMed

Wang, Zhengmu; Zhang, Hongbin; Chu, Axel J; Jackson, John; Lin, Karen; Lim, Chinten James; Lange, Dirk; Chiao, Mu

2018-04-01

Well-organized composite formations such as hierarchical nested-network (NN) structure in bone tissue and reticular connective tissue present remarkable mechanical strength and play a crucial role in achieving physical and biological functions for living organisms. Inspired by these delicate microstructures in nature, an analogous scaffold of double network hydrogel was fabricated by creating a poly(2-hydroxyethyl methacrylate) (pHEMA) network in the porous structure of alginate hydrogels. The resulting hydrogel possessed hierarchical NN structure and showed significantly improved mechanical strength but still maintained high elasticity comparable to soft tissues due to a mutual strengthening effect between the two networks. The tough hydrogel is also self-lubricated, exhibiting a surface friction coefficient comparable with polydimethylsiloxane (PDMS) substrates lubricated by a commercial aqueous lubricant (K-Y Jelly) and other low surface friction hydrogels. Additional properties of this hydrogel include high hydrophilicity, good biocompatibility, tunable cell adhesion and bacterial resistance after incorporation of silver nanoparticles. Firm bonding of the hydrogel on silicone substrates could be achieved through facile chemical modification, thus enabling the use of this hydrogel as a versatile coating material for biomedical applications. In this study, we developed a tough hydrogel by crosslinking HEMA monomers in alginate hydrogels and forming a well-organized structure of hierarchical nested network (NN). Different from most reported stretchable alginate-based hydrogels, the NN hydrogel shows higher compressive strength but retains comparable softness to alginate counterparts. This work further demonstrated the good integration of the tough hydrogel with silicone substrates through chemical modification and micropillar structures. Other properties including surface friction, biocompatibility and bacterial resistance were investigated and the hydrogel shows a great promise as a versatile coating material for biomedical applications. Copyright © 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Remote control of molecular motors using light-activated gearshifting

NASA Astrophysics Data System (ADS)

Bryant, Zev

2013-03-01

Engineering molecular motors with dynamically controllable properties will allow selective perturbation of mechanical processes in vivo and provide sophisticated components for directed nanoscale transport in vitro. We previously constructed myosin motors that respond to a change in [Ca++] by reversing their direction of motion along the polarized actin filament. To expand the potential applications of controllable molecular motors, we have now developed myosins that shift gears in response to blue light illumination. Light is a versatile control signal that can be readily modulated in time and space, and is generally orthogonal to cellular signaling. Using structure-guided protein engineering, we have incorporated LOV photoreceptor domains into the lever arms of chimeric myosins, resulting in motors that robustly speed up, slow down, or switch directions upon illumination. These genetically encoded motors should be directly deployable inside living cells. Our successful designs include constructs based on two different myosin classes, and we show that optical velocity control can be implemented in motors that move at microns/sec speeds, enabling practical biological and bioengineering applications.

Directed evolution of enzymes using microfluidic chips

NASA Astrophysics Data System (ADS)

Pilát, Zdeněk.; Ježek, Jan; Šmatlo, Filip; Kaůka, Jan; Zemánek, Pavel

2016-12-01

Enzymes are highly versatile and ubiquitous biological catalysts. They can greatly accelerate large variety of reactions, while ensuring appropriate catalytic activity and high selectivity. These properties make enzymes attractive biocatalysts for a wide range of industrial and biomedical applications. Over the last two decades, directed evolution of enzymes has transformed the field of protein engineering. We have devised microfluidic systems for directed evolution of haloalkane dehalogenases in emulsion droplets. In such a device, individual bacterial cells producing mutated variants of the same enzyme are encapsulated in microdroplets and supplied with a substrate. The conversion of a substrate by the enzyme produced by a single bacterium changes the pH in the droplet which is signalized by pH dependent fluorescence probe. The droplets with the highest enzymatic activity can be separated directly on the chip by dielectrophoresis and the resultant cell lineage can be used for enzyme production or for further rounds of directed evolution. This platform is applicable for fast screening of large libraries in directed evolution experiments requiring mutagenesis at multiple sites of a protein structure.

The roles of B vitamins in phytoplankton nutrition: new perspectives and prospects.

PubMed

Helliwell, Katherine E

2017-10-01

Contents 62 I. 62 II. 63 III. 63 IV. 66 V. 66 VI. 67 67 References 67 SUMMARY: B vitamins play essential roles in central metabolism. These organic water-soluble molecules act as, or as part of, coenzymes within the cell. Unlike land plants, many eukaryotic algae are auxotrophic for certain B vitamins. Recent progress in algal genetic resources and environmental chemistry have promoted a renewal of interest in the role of vitamins in governing phytoplankton dynamics, and illuminated amazing versatility in phytoplankton vitamin metabolism. Accumulating evidence demonstrates metabolic complexity in the production and bioavailability of different vitamin forms, coupled with specialized acquisition strategies to salvage and remodel vitamin precursors. Here, I describe recent advances and discuss how they redefine our view of the way in which vitamins are cycled in aquatic ecosystems and their importance in structuring phytoplankton communities. © 2017 The Author. New Phytologist © 2017 New Phytologist Trust.

Type IV Collagens and Basement Membrane Diseases: Cell Biology and Pathogenic Mechanisms.

PubMed

Mao, Mao; Alavi, Marcel V; Labelle-Dumais, Cassandre; Gould, Douglas B

2015-01-01

Basement membranes are highly specialized extracellular matrices. Once considered inert scaffolds, basement membranes are now viewed as dynamic and versatile environments that modulate cellular behaviors to regulate tissue development, function, and repair. Increasing evidence suggests that, in addition to providing structural support to neighboring cells, basement membranes serve as reservoirs of growth factors that direct and fine-tune cellular functions. Type IV collagens are a major component of all basement membranes. They evolved along with the earliest multicellular organisms and have been integrated into diverse fundamental biological processes as time and evolution shaped the animal kingdom. The roles of basement membranes in humans are as complex and diverse as their distributions and molecular composition. As a result, basement membrane defects result in multisystem disorders with ambiguous and overlapping boundaries that likely reflect the simultaneous interplay and integration of multiple cellular pathways and processes. Consequently, there will be no single treatment for basement membrane disorders, and therapies are likely to be as varied as the phenotypes. Understanding tissue-specific pathology and the underlying molecular mechanism is the present challenge; personalized medicine will rely upon understanding how a given mutation impacts diverse cellular functions. Copyright © 2015 Elsevier Inc. All rights reserved.

Biosurfactants: Promising Molecules for Petroleum Biotechnology Advances.

PubMed

De Almeida, Darne G; Soares Da Silva, Rita de Cássia F; Luna, Juliana M; Rufino, Raquel D; Santos, Valdemir A; Banat, Ibrahim M; Sarubbo, Leonie A

2016-01-01

The growing global demand for sustainable technologies that improves the efficiency of petrochemical processes in the oil industry has driven advances in petroleum biotechnology in recent years. Petroleum industry uses substantial amounts of petrochemical-based synthetic surfactants in its activities as mobilizing agents to increase the availability or recovery of hydrocarbons as well as many other applications related to extraction, treatment, cleaning, and transportation. However, biosurfactants have several potential applications for use across the oil processing chain and in the formulations of petrochemical products such as emulsifying/demulsifying agents, anticorrosive, biocides for sulfate-reducing bacteria, fuel formulation, extraction of bitumen from tar sands, and many other innovative applications. Due to their versatility and proven efficiency, biosurfactants are often presented as valuable versatile tools that can transform and modernize petroleum biotechnology in an attempt to provide a true picture of state of the art and directions or use in the oil industry. We believe that biosurfactants are going to have a significant role in many future applications in the oil industries and in this review therefore, we highlight recent important relevant applications, patents disclosures and potential future applications for biosurfactants in petroleum and related industries.

Biosurfactants: Promising Molecules for Petroleum Biotechnology Advances

PubMed Central

De Almeida, Darne G.; Soares Da Silva, Rita de Cássia F.; Luna, Juliana M.; Rufino, Raquel D.; Santos, Valdemir A.; Banat, Ibrahim M.; Sarubbo, Leonie A.

2016-01-01

The growing global demand for sustainable technologies that improves the efficiency of petrochemical processes in the oil industry has driven advances in petroleum biotechnology in recent years. Petroleum industry uses substantial amounts of petrochemical-based synthetic surfactants in its activities as mobilizing agents to increase the availability or recovery of hydrocarbons as well as many other applications related to extraction, treatment, cleaning, and transportation. However, biosurfactants have several potential applications for use across the oil processing chain and in the formulations of petrochemical products such as emulsifying/demulsifying agents, anticorrosive, biocides for sulfate-reducing bacteria, fuel formulation, extraction of bitumen from tar sands, and many other innovative applications. Due to their versatility and proven efficiency, biosurfactants are often presented as valuable versatile tools that can transform and modernize petroleum biotechnology in an attempt to provide a true picture of state of the art and directions or use in the oil industry. We believe that biosurfactants are going to have a significant role in many future applications in the oil industries and in this review therefore, we highlight recent important relevant applications, patents disclosures and potential future applications for biosurfactants in petroleum and related industries. PMID:27843439

High Efficiency Variable Speed Versatile Power Air Conditioning System for Military Vehicles

DTIC Science & Technology

2013-08-01

MOBILITY (P&M) MINI-SYMPOSIUM AUGUST 21-22, 2013 - TROY , MICHIGAN High efficiency variable speed versatile power air conditioning system for...power draw was measured using a calibrated Watt meter. The schematic of the setup is shown in Figure 5 and the setup is shown in Figure 6. Figure...Rocky Research environmental chamber. Cooling Capacity was directly measured in Btu/hr or Watts via measuring the Air flow velocity and the air

Ipomoelin, a Jacalin-Related Lectin with a Compact Tetrameric Association and Versatile Carbohydrate Binding Properties Regulated by Its N Terminus

PubMed Central

Chang, Wei-Chieh; Liu, Kai-Lun; Hsu, Fang-Ciao; Jeng, Shih-Tong; Cheng, Yi-Sheng

2012-01-01

Many proteins are induced in the plant defense response to biotic stress or mechanical wounding. One group is lectins. Ipomoelin (IPO) is one of the wound-inducible proteins of sweet potato (Ipomoea batatas cv. Tainung 57) and is a Jacalin-related lectin (JRL). In this study, we resolved the crystal structures of IPO in its apo form and in complex with carbohydrates such as methyl α-D-mannopyranoside (Me-Man), methyl α-D-glucopyranoside (Me-Glc), and methyl α-D-galactopyranoside (Me-Gal) in different space groups. The packing diagrams indicated that IPO might represent a compact tetrameric association in the JRL family. The protomer of IPO showed a canonical β-prism fold with 12 strands of β-sheets but with 2 additional short β-strands at the N terminus. A truncated IPO (ΔN10IPO) by removing the 2 short β-strands of the N terminus was used to reveal its role in a tetrameric association. Gel filtration chromatography confirmed IPO as a tetrameric form in solution. Isothermal titration calorimetry determined the binding constants (KA) of IPO and ΔN10IPO against various carbohydrates. IPO could bind to Me-Man, Me-Glc, and Me-Gal with similar binding constants. In contrast, ΔN10IPO showed high binding ability to Me-Man and Me-Glc but could not bind to Me-Gal. Our structural and functional analysis of IPO revealed that its compact tetrameric association and carbohydrate binding polyspecificity could be regulated by the 2 additional N-terminal β-strands. The versatile carbohydrate binding properties of IPO might play a role in plant defense. PMID:22808208

A highly sensitive ethanol sensor based on mesoporous ZnO-SnO2 nanofibers.

PubMed

Song, Xiaofeng; Wang, Zhaojie; Liu, Yongben; Wang, Ce; Li, Lijuan

2009-02-18

A facile and versatile method for the large-scale synthesis of sensitive mesoporous ZnO-SnO(2) (m-Z-S) nanofibers through a combination of surfactant-directed assembly and an electrospinning approach is reported. The morphology and the structure were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), x-ray diffraction (XRD), and nitrogen adsorption-desorption isotherm analysis. The results showed that the diameters of fibers ranged from 100 to 150 nm with mixed structures of wurtzite (ZnO) and rutile (SnO(2)), and a mesoporous structure was observed in the m-Z-S nanofibers. The sensor performance of the prepared m-Z-S nanofibers was measured for ethanol. It is found that the mesoporous fiber film obtained exhibited excellent ethanol sensing properties, such as high sensitivity, quick response and recovery, good reproducibility, and linearity in the range 3-500 ppm.

Uncovering the spatial structure of mobility networks

NASA Astrophysics Data System (ADS)

Louail, Thomas; Lenormand, Maxime; Picornell, Miguel; García Cantú, Oliva; Herranz, Ricardo; Frias-Martinez, Enrique; Ramasco, José J.; Barthelemy, Marc

2015-01-01

The extraction of a clear and simple footprint of the structure of large, weighted and directed networks is a general problem that has relevance for many applications. An important example is seen in origin-destination matrices, which contain the complete information on commuting flows, but are difficult to analyze and compare. We propose here a versatile method, which extracts a coarse-grained signature of mobility networks, under the form of a 2 × 2 matrix that separates the flows into four categories. We apply this method to origin-destination matrices extracted from mobile phone data recorded in 31 Spanish cities. We show that these cities essentially differ by their proportion of two types of flows: integrated (between residential and employment hotspots) and random flows, whose importance increases with city size. Finally, the method allows the determination of categories of networks, and in the mobility case, the classification of cities according to their commuting structure.

α-Haloaldehydes: versatile building blocks for natural product synthesis.

PubMed

Britton, Robert; Kang, Baldip

2013-02-01

The diastereoselective addition of organometallic reagents to α-chloroaldehydes was first reported in 1959 and occupies a historically significant role as the prototypical reaction for Cornforth's model of stereoinduction. Despite clear synthetic potential for these reagents, difficulties associated with producing enantiomerically enriched α-haloaldehydes limited their use in natural product synthesis through the latter half of the 20th century. In recent years, however, a variety of robust, organocatalytic processes have been reported that now provide direct access to optically enriched α-haloaldehydes and have motivated renewed interest in their use as building blocks for natural product synthesis. This Highlight summarizes the methods available for the enantioselective preparation of α-haloaldehydes and their stereoselective conversion into natural products.

Determination of line profiles on nano-structured surfaces using EUV and x-ray scattering

NASA Astrophysics Data System (ADS)

Soltwisch, Victor; Wernecke, Jan; Haase, Anton; Probst, Jürgen; Schoengen, Max; Krumrey, Michael; Scholze, Frank; Pomplun, Jan; Burger, Sven

2014-09-01

Non-imaging techniques like X-ray scattering are supposed to play an important role in the further development of CD metrology for the semiconductor industry. Grazing Incidence Small Angle X-ray Scattering (GISAXS) provides directly assessable information on structure roughness and long-range periodic perturbations. The disadvantage of the method is the large footprint of the X-ray beam on the sample due to the extremely shallow angle of incidence. This can be overcome by using wavelengths in the extreme ultraviolet (EUV) spectral range, EUV small angle scattering (EUVSAS), which allows for much steeper angles of incidence but preserves the range of momentum transfer that can be observed. Generally, the potentially higher momentum transfer at shorter wavelengths is counterbalanced by decreasing diffraction efficiency. This results in a practical limit of about 10 nm pitch for which it is possible to observe at least the +/- 1st diffraction orders with reasonable efficiency. At the Physikalisch-Technische Bundesanstalt (PTB), the available photon energy range extends from 50 eV up to 10 keV at two adjacent beamlines. PTB commissioned a new versatile Ellipso-Scatterometer which is capable of measuring 6" square substrates in a clean, hydrocarbon-free environment with full flexibility regarding the direction of the incident light polarization. The reconstruction of line profiles using a geometrical model with six free parameters, based on a finite element method (FEM) Maxwell solver and a particle swarm based least-squares optimization yielded consistent results for EUV-SAS and GISAXS. In this contribution we present scatterometry data for line gratings and consistent reconstruction results of the line geometry for EUV-SAS and GISAXS.

Restricted amide rotation with steric hindrance induced multiple conformations

NASA Astrophysics Data System (ADS)

Krishnan, V. V.; Vazquez, Salvador; Maitra, Kalyani; Maitra, Santanu

2017-12-01

The Csbnd N bond character is dependent directly upon the resonance-contributor structure population driven by the delocalized nitrogen lone-pair of electrons. In the case of N, N-dibenzyl-ortho-toluamide (o-DBET), the molecule adopts subpopulations of conformers with distinct NMR spectral features, particularly at low temperatures. This conformational adaptation is unique to o-DBET, while the corresponding meta- and para- forms do not show such behavior. Variable-temperature (VT) NMR, two-dimensional exchange spectroscopy (EXSY), and qualitative molecular modeling studies are used to demonstrate how multiple competing interactions such as restricted amide rotation and steric hindrance effects can lead to versatile molecular adaptations in the solution state.

Clinical application of endoscopic ultrasonography for esophageal achalasia.

PubMed

Minami, Hitomi; Inoue, Haruhiro; Isomoto, Hajime; Urabe, Shigetoshi; Nakao, Kazuhiko

2015-04-01

Endoscopic ultrasonography (EUS) has been widely used for evaluating the nature of diseases of various organs. The possibility of applying EUS for esophageal motility diseases has not been well discussed despite its versatility. At present, peroral endoscopic myotomy (POEM) for esophageal achalasia and related diseases has brought new attention to esophageal diseases because POEM provides a more direct approach to the inner structures of the esophageal wall. In the present study, we discuss the clinical utility of EUS in evaluating and treating esophageal motility diseases such as esophageal achalasia and related diseases. © 2015 The Authors. Digestive Endoscopy © 2015 Japan Gastroenterological Endoscopy Society.

Active thermography in qualitative evaluation of protective materials.

PubMed

Gralewicz, Grzegorz; Wiecek, Bogusław

2009-01-01

This is a study of the possibilities of a qualitative evaluation of protective materials with active thermography. It presents a simulation of a periodic excitation of a multilayer composite material. Tests were conducted with lock-in thermography on Kevlar composite consisting of 16 layers of Kevlar fabric reinforced with formaldehyde resin with implanted delamination defects. Lock-in thermography is a versatile tool for nondestructive evaluation. It is a fast, remote and nondestructive procedure. Hence, it was used to detect delaminations in the composite structure of materials used in the production of components designed for personal protection. This method directly contributes to an improvement in safety.

The role of general nuclear medicine in breast cancer

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

Greene, Lacey R, E-mail: lgreene@csu.edu.au; Wilkinson, Deborah; Faculty of Science, Charles Sturt University, Wagga Wagga, New South Wales

The rising incidence of breast cancer worldwide has prompted many improvements to current care. Routine nuclear medicine is a major contributor to a full gamut of clinical studies such as early lesion detection and stratification; guiding, monitoring, and predicting response to therapy; and monitoring progression, recurrence or metastases. Developments in instrumentation such as the high-resolution dedicated breast device coupled with the diagnostic versatility of conventional cameras have reinserted nuclear medicine as a valuable tool in the broader clinical setting. This review outlines the role of general nuclear medicine, concluding that targeted radiopharmaceuticals and versatile instrumentation position nuclear medicine as amore » powerful modality for patients with breast cancer.« less

Mushroom Lectins: Specificity, Structure and Bioactivity Relevant to Human Disease

PubMed Central

Hassan, Mohamed Ali Abol; Rouf, Razina; Tiralongo, Evelin; May, Tom W.; Tiralongo, Joe

2015-01-01

Lectins are non-immunoglobulin proteins that bind diverse sugar structures with a high degree of selectivity. Lectins play crucial role in various biological processes such as cellular signaling, scavenging of glycoproteins from the circulatory system, cell–cell interactions in the immune system, differentiation and protein targeting to cellular compartments, as well as in host defence mechanisms, inflammation, and cancer. Among all the sources of lectins, plants have been most extensively studied. However, more recently fungal lectins have attracted considerable attention due to their antitumor, antiproliferative and immunomodulatory activities. Given that only 10% of mushroom species are known and have been taxonomically classified, mushrooms represent an enormous unexplored source of potentially useful and novel lectins. In this review we provide an up-to-date summary on the biochemical, molecular and structural properties of mushroom lectins, as well as their versatile applications specifically focusing on mushroom lectin bioactivity. PMID:25856678

Molecular structure and differential function of choline kinases CHKα and CHKβ in musculoskeletal system and cancer.

PubMed

Chen, Xi; Qiu, Heng; Wang, Chao; Yuan, Yu; Tickner, Jennifer; Xu, Jiake; Zou, Jun

2017-02-01

Choline, a hydrophilic cation, has versatile physiological roles throughout the body, including cholinergic neurotransmission, memory consolidation and membrane biosynthesis and metabolism. Choline kinases possess enzyme activity that catalyses the conversion of choline to phosphocholine, which is further converted to cytidine diphosphate-coline (CDP-choline) in the biosynthesis of phosphatidylcholine (PC). PC is a major constituent of the phospholipid bilayer which constitutes the eukaryotic cell membrane, and regulates cell signal transduction. Choline Kinase consists of three isoforms, CHKα1, CHKα2 and CHKβ, encoded by two separate genes (CHKA(Human)/Chka(Mouse) and CHKB(Human)/Chkb(Mouse)). Both isoforms have similar structures and enzyme activity, but display some distinct molecular structural domains and differential tissue expression patterns. Whilst Choline Kinase was discovered in early 1950, its pivotal role in the development of muscular dystrophy, bone deformities, and cancer has only recently been identified. CHKα has been proposed as a cancer biomarker and its inhibition as an anti-cancer therapy. In contrast, restoration of CHKβ deficiency through CDP-choline supplements like citicoline may be beneficial for the treatment of muscular dystrophy, bone metabolic diseases, and cognitive conditions. The molecular structure and expression pattern of Choline Kinase, the differential roles of Choline Kinase isoforms and their potential as novel therapeutic targets for muscular dystrophy, bone deformities, cognitive conditions and cancer are discussed. Copyright © 2016. Published by Elsevier Ltd.

SiC-Based Schottky Diode Gas Sensors

NASA Technical Reports Server (NTRS)

Hunter, Gary W.; Neudeck, Philip G.; Chen, Liang-Yu; Knight, Dak; Liu, Chung-Chiun; Wu, Quing-Hai

1997-01-01

Silicon carbide based Schottky diode gas sensors are being developed for high temperature applications such as emission measurements. Two different types of gas sensitive diodes will be discussed in this paper. By varying the structure of the diode, one can affect the diode stability as well as the diode sensitivity to various gases. It is concluded that the ability of SiC to operate as a high temperature semiconductor significantly enhances the versatility of the Schottky diode gas sensing structure and will potentially allow the fabrication of a SiC-based gas sensor arrays for versatile high temperature gas sensing applications.

The underlying role of posttraumatic stress disorder symptoms in the association between intimate partner violence and deliberate self-harm among African American women.

PubMed

Weiss, Nicole H; Dixon-Gordon, Katherine L; Duke, Aaron A; Sullivan, Tami P

2015-05-01

African American women are at heightened risk for intimate partner violence (IPV) and its negative consequences, including health-compromising behaviors. Deliberate self-harm (DSH) is one clinically-relevant behavior that has been understudied among African American women generally and those with exposure to IPV in particular. To date, no studies have examined factors that may account for the relationship between IPV and DSH. Therefore, the goal of the present study was to examine the intercorrelations among IPV (physical, psychological, and sexual), PTSD, and DSH history and versatility, and the potentially mediating role of PTSD symptoms in the IPV-DSH relation. Participants were 197 African American community women currently experiencing IPV. Sixty participants (31%) reported a history of DSH. Among participants who reported DSH, there was an average endorsement of 2.3 unique forms of deliberate self-harm (i.e., DSH versatility). Significant positive associations were detected among physical IPV severity, psychological IPV severity, PTSD symptom severity, and DSH history and versatility. PTSD symptom severity mediated the relationships between physical and psychological IPV severity and DSH history and versatility. Results highlight the relevance of PTSD symptoms to DSH and suggest that treatments targeting PTSD symptoms may be useful in reducing DSH among IPV-exposed African American women. Copyright © 2014. Published by Elsevier Inc.

Magnetically-refreshable receptor platform structures for reusable nano-biosensor chips

NASA Astrophysics Data System (ADS)

Yoo, Haneul; Lee, Dong Jun; Cho, Dong-guk; Park, Juhun; Nam, Ki Wan; Tak Cho, Young; Park, Jae Yeol; Chen, Xing; Hong, Seunghun

2016-01-01

We developed a magnetically-refreshable receptor platform structure which can be integrated with quite versatile nano-biosensor structures to build reusable nano-biosensor chips. This structure allows one to easily remove used receptor molecules from a biosensor surface and reuse the biosensor for repeated sensing operations. Using this structure, we demonstrated reusable immunofluorescence biosensors. Significantly, since our method allows one to place receptor molecules very close to a nano-biosensor surface, it can be utilized to build reusable carbon nanotube transistor-based biosensors which require receptor molecules within a Debye length from the sensor surface. Furthermore, we also show that a single sensor chip can be utilized to detect two different target molecules simply by replacing receptor molecules using our method. Since this method does not rely on any chemical reaction to refresh sensor chips, it can be utilized for versatile biosensor structures and virtually-general receptor molecular species.

Robust Superhydrophobic Carbon Nanotube Film with Lotus Leaf Mimetic Multiscale Hierarchical Structures.

PubMed

Wang, Pengwei; Zhao, Tianyi; Bian, Ruixin; Wang, Guangyan; Liu, Huan

2017-12-26

Superhydrophobic carbon nanotube (CNT) films have demonstrated many fascinating performances in versatile applications, especially for those involving solid/liquid interfacial processes, because of their ability to affect the material/energy transfer at interfaces. Thus, developing superhydrophobic CNTs has attracted extensive research interests in the past decades, and it could be achieved either by surface coating of low-free energy materials or by constructing micro/nanohierarchical structures via various complicated processes. So far, developing a simple approach to fabricate stable superhydrophobic CNTs remains a challenge because the capillary force induced coalescence frequently happens when interacting with liquid. Herein, drawing inspirations from the lotus leaf, we proposed a simple one-step chemical vapor deposition approach with programmable controlled gas flow to directly fabricate a CNT film with rather stable superhydrophobicity, which can effectively prevent even small water droplets from permeating into the film. The robust superhydrophobicity was attributable to typical lotus-leaf-like micro/nanoscale hierarchical surface structures of the CNT film, where many microscale clusters composed of entangled nanotubes randomly protrude out of the under-layer aligned nanotubes. Consequently, dual-scale air pockets were trapped within each microscale CNT cluster and between, which could largely reduce the liquid/solid interface, leading to a Cassie state. Moreover, the superhydrophobicity of the CNT film showed excellent durability after long time exposure to air and even to corrosive liquids with a wide range of pH values. We envision that the approach developed is advantageous for versatile physicochemical interfacial processes, such as drag reduction, electrochemical catalysis, anti-icing, and biosensors.

Robustness and versatility of a nonlinear interdependence method for directional coupling detection from spike trains.

PubMed

Malvestio, Irene; Kreuz, Thomas; Andrzejak, Ralph G

2017-08-01

The detection of directional couplings between dynamics based on measured spike trains is a crucial problem in the understanding of many different systems. In particular, in neuroscience it is important to assess the connectivity between neurons. One of the approaches that can estimate directional coupling from the analysis of point processes is the nonlinear interdependence measure L. Although its efficacy has already been demonstrated, it still needs to be tested under more challenging and realistic conditions prior to an application to real data. Thus, in this paper we use the Hindmarsh-Rose model system to test the method in the presence of noise and for different spiking regimes. We also examine the influence of different parameters and spike train distances. Our results show that the measure L is versatile and robust to various types of noise, and thus suitable for application to experimental data.

Robustness and versatility of a nonlinear interdependence method for directional coupling detection from spike trains

NASA Astrophysics Data System (ADS)

Malvestio, Irene; Kreuz, Thomas; Andrzejak, Ralph G.

2017-08-01

The detection of directional couplings between dynamics based on measured spike trains is a crucial problem in the understanding of many different systems. In particular, in neuroscience it is important to assess the connectivity between neurons. One of the approaches that can estimate directional coupling from the analysis of point processes is the nonlinear interdependence measure L . Although its efficacy has already been demonstrated, it still needs to be tested under more challenging and realistic conditions prior to an application to real data. Thus, in this paper we use the Hindmarsh-Rose model system to test the method in the presence of noise and for different spiking regimes. We also examine the influence of different parameters and spike train distances. Our results show that the measure L is versatile and robust to various types of noise, and thus suitable for application to experimental data.

High-performance liquid chromatography of oligoguanylates at high pH

NASA Technical Reports Server (NTRS)

Stribling, R.; Deamer, D. (Principal Investigator)

1991-01-01

Because of the stable self-structures formed by oligomers of guanosine, standard high-performance liquid chromatography techniques for oligonucleotide fractionation are not applicable. Previously, oligoguanylate separations have been carried out at pH 12 using RPC-5 as the packing material. While RPC-5 provides excellent separations, there are several limitations, including the lack of a commercially available source. This report describes a new anion-exchange high-performance liquid chromatography method using HEMA-IEC BIO Q, which successfully separates different forms of the guanosine monomer as well as longer oligoguanylates. The reproducibility and stability at high pH suggests a versatile role for this material.

Nanoimprint of a 3D structure on an optical fiber for light wavefront manipulation.

PubMed

Calafiore, Giuseppe; Koshelev, Alexander; Allen, Frances I; Dhuey, Scott; Sassolini, Simone; Wong, Edward; Lum, Paul; Munechika, Keiko; Cabrini, Stefano

2016-09-16

Integration of complex photonic structures onto optical fiber facets enables powerful platforms with unprecedented optical functionalities. Conventional nanofabrication technologies, however, do not permit viable integration of complex photonic devices onto optical fibers owing to their low throughput and high cost. In this paper we report the fabrication of a three-dimensional structure achieved by direct nanoimprint lithography on the facet of an optical fiber. Nanoimprint processes and tools were specifically developed to enable a high lithographic accuracy and coaxial alignment of the optical device with respect to the fiber core. To demonstrate the capability of this new approach, a 3D beam splitter has been designed, imprinted and optically characterized. Scanning electron microscopy and optical measurements confirmed the good lithographic capabilities of the proposed approach as well as the desired optical performance of the imprinted structure. The inexpensive solution presented here should enable advancements in areas such as integrated optics and sensing, achieving enhanced portability and versatility of fiber optic components.

Observation of Bloch oscillations in complex PT-symmetric photonic lattices

PubMed Central

Wimmer, Martin; Miri, Mohammed-Ali; Christodoulides, Demetrios; Peschel, Ulf

2015-01-01

Light propagation in periodic environments is often associated with a number of interesting and potentially useful processes. If a crystalline optical potential is also linearly ramped, light can undergo periodic Bloch oscillations, a direct outcome of localized Wannier-Stark states and their equidistant eigenvalue spectrum. Even though these effects have been extensively explored in conservative settings, this is by no means the case in non-Hermitian photonic lattices encompassing both amplification and attenuation. Quite recently, Bloch oscillations have been predicted in parity-time-symmetric structures involving gain and loss in a balanced fashion. While in a complex bulk medium, one intuitively expects that light will typically follow the path of highest amplification, in a periodic system this behavior can be substantially altered by the underlying band structure. Here, we report the first experimental observation of Bloch oscillations in parity-time-symmetric mesh lattices. We show that these revivals exhibit unusual properties like secondary emissions and resonant restoration of PT symmetry. In addition, we present a versatile method for reconstructing the real and imaginary components of the band structure by directly monitoring the light evolution during a cycle of these oscillations. PMID:26639941

Observation of Bloch oscillations in complex PT-symmetric photonic lattices

NASA Astrophysics Data System (ADS)

Wimmer, Martin; Miri, Mohammed-Ali; Christodoulides, Demetrios; Peschel, Ulf

2015-12-01

Light propagation in periodic environments is often associated with a number of interesting and potentially useful processes. If a crystalline optical potential is also linearly ramped, light can undergo periodic Bloch oscillations, a direct outcome of localized Wannier-Stark states and their equidistant eigenvalue spectrum. Even though these effects have been extensively explored in conservative settings, this is by no means the case in non-Hermitian photonic lattices encompassing both amplification and attenuation. Quite recently, Bloch oscillations have been predicted in parity-time-symmetric structures involving gain and loss in a balanced fashion. While in a complex bulk medium, one intuitively expects that light will typically follow the path of highest amplification, in a periodic system this behavior can be substantially altered by the underlying band structure. Here, we report the first experimental observation of Bloch oscillations in parity-time-symmetric mesh lattices. We show that these revivals exhibit unusual properties like secondary emissions and resonant restoration of PT symmetry. In addition, we present a versatile method for reconstructing the real and imaginary components of the band structure by directly monitoring the light evolution during a cycle of these oscillations.

One-step patterning of double tone high contrast and high refractive index inorganic spin-on resist

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

Zanchetta, E.; Della Giustina, G.; Brusatin, G.

2014-09-14

A direct one-step and low temperature micro-fabrication process, enabling to realize large area totally inorganic TiO₂ micro-patterns from a spin-on resist, is presented. High refractive index structures (up to 2 at 632 nm) without the need for transfer processes have been obtained by mask assisted UV lithography, exploiting photocatalytic titania properties. A distinctive feature not shared by any of the known available resists and boosting the material versatility, is that the system behaves either as a positive or as negative tone resist, depending on the process parameters and on the development chemistry. In order to explain the resist double tonemore » behavior, deep comprehension of the lithographic process parameters optimization and of the resist chemistry and structure evolution during the lithographic process, generally uncommon in literature, is reported. Another striking property of the presented resist is that the negative tone shows a high contrast up to 19, allowing to obtain structures resolution down to 2 μm wide. The presented process and material permit to directly fabricate different titania geometries of great importance for solar cells, photo-catalysis, and photonic crystals applications.« less

Four Chemical Trends Will Shape the Next Decade's Directions in Perfluoroalkyl and Polyfluoroalkyl Substances Research.

PubMed

Kotthoff, Matthias; Bücking, Mark

2018-01-01

Per- and polyfluoroalkyl substances (PFAS) represent a versatile group of ubiquitously occurring chemicals of increasing regulatory concern. The past years lead to an ever expanding portfolio of detected anthropogenic PFAS in numerous products encountered in daily life. Yet no clear picture of the full range of individual substance that comprise PFAS is available and this challenges analytical and engineering sciences. Authorities struggle to cope with uncertainties in managing risk of harm posed by PFAS. This is a result of an incomplete understanding of the range of compounds that they comprise in differing products. There are analytical uncertainties identifying PFAS and estimating the concentrations of the total PFAS load individual molecules remain unknown. There are four major trends from the chemical perspective that will shape PFAS research for the next decade. Mobility: A wide and dynamic distribution of short chain PFAS due to their high polarity, persistency and volatility.Substitution of regulated substances: The ban or restrictions of individual molecules will lead to a replacement with substitutes of similar concern.Increase in structural diversity of existing PFAS molecules: Introduction of e.g., hydrogens and chlorine atoms instead of fluorine, as well as branching and cross-linking lead to a high versatility of unknown target molecules.Unknown "Dark Matter": The amount, identity, formation pathways, and transformation dynamics of polymers and PFAS precursors are largely unknown. These directions require optimized analytical setups, especially multi-methods, and semi-specific tools to determine PFAS-sum parameters in any relevant matrix.

Four Chemical Trends Will Shape the Next Decade's Directions in Perfluoroalkyl and Polyfluoroalkyl Substances Research

PubMed Central

Kotthoff, Matthias; Bücking, Mark

2018-01-01

Per- and polyfluoroalkyl substances (PFAS) represent a versatile group of ubiquitously occurring chemicals of increasing regulatory concern. The past years lead to an ever expanding portfolio of detected anthropogenic PFAS in numerous products encountered in daily life. Yet no clear picture of the full range of individual substance that comprise PFAS is available and this challenges analytical and engineering sciences. Authorities struggle to cope with uncertainties in managing risk of harm posed by PFAS. This is a result of an incomplete understanding of the range of compounds that they comprise in differing products. There are analytical uncertainties identifying PFAS and estimating the concentrations of the total PFAS load individual molecules remain unknown. There are four major trends from the chemical perspective that will shape PFAS research for the next decade. Mobility: A wide and dynamic distribution of short chain PFAS due to their high polarity, persistency and volatility.Substitution of regulated substances: The ban or restrictions of individual molecules will lead to a replacement with substitutes of similar concern.Increase in structural diversity of existing PFAS molecules: Introduction of e.g., hydrogens and chlorine atoms instead of fluorine, as well as branching and cross-linking lead to a high versatility of unknown target molecules.Unknown “Dark Matter”: The amount, identity, formation pathways, and transformation dynamics of polymers and PFAS precursors are largely unknown. These directions require optimized analytical setups, especially multi-methods, and semi-specific tools to determine PFAS-sum parameters in any relevant matrix. PMID:29675408

Mario Becomes Cognitive.

PubMed

Schrodt, Fabian; Kneissler, Jan; Ehrenfeld, Stephan; Butz, Martin V

2017-04-01

In line with Allen Newell's challenge to develop complete cognitive architectures, and motivated by a recent proposal for a unifying subsymbolic computational theory of cognition, we introduce the cognitive control architecture SEMLINCS. SEMLINCS models the development of an embodied cognitive agent that learns discrete production rule-like structures from its own, autonomously gathered, continuous sensorimotor experiences. Moreover, the agent uses the developing knowledge to plan and control environmental interactions in a versatile, goal-directed, and self-motivated manner. Thus, in contrast to several well-known symbolic cognitive architectures, SEMLINCS is not provided with production rules and the involved symbols, but it learns them. In this paper, the actual implementation of SEMLINCS causes learning and self-motivated, autonomous behavioral control of the game figure Mario in a clone of the computer game Super Mario Bros. Our evaluations highlight the successful development of behavioral versatility as well as the learning of suitable production rules and the involved symbols from sensorimotor experiences. Moreover, knowledge- and motivation-dependent individualizations of the agents' behavioral tendencies are shown. Finally, interaction sequences can be planned on the sensorimotor-grounded production rule level. Current limitations directly point toward the need for several further enhancements, which may be integrated into SEMLINCS in the near future. Overall, SEMLINCS may be viewed as an architecture that allows the functional and computational modeling of embodied cognitive development, whereby the current main focus lies on the development of production rules from sensorimotor experiences. Copyright © 2017 Cognitive Science Society, Inc.

Versatile hydrothermal synthesis of one-dimensional composite structures

NASA Astrophysics Data System (ADS)

Luo, Yonglan

2008-12-01

In this paper we report on a versatile hydrothermal approach developed to fabricate one-dimensional (1D) composite structures. Sulfur and selenium formed liquid and adsorbed onto microrods as droplets and subsequently reacted with metallic ion in solution to produce nanoparticles-decorated composite microrods. 1D composites including ZnO/CdS, ZnO/MnS, ZnO/CuS, ZnO/CdSe, and FeOOH/CdS were successfully made using this hydrothermal strategy and the growth mechanism was also discussed. This hydrothermal strategy is simple and green, and can be extended to the synthesis of various 1D composite structures. Moreover, the interaction between the shell nanoparticles and the one-dimensional nanomaterials were confirmed by photoluminescence investigation of ZnO/CdS.

Robotic large-scale application of wheat cell-free translation to structural studies including membrane proteins

PubMed Central

Beebe, Emily T.; Makino, Shin-ichi; Nozawa, Akira; Matsubara, Yuko; Frederick, Ronnie O.; Primm, John G.; Goren, Michael A.; Fox, Brian G.

2010-01-01

The use of the Protemist XE, an automated discontinuous-batch protein synthesis robot, in cell-free translation is reported. The soluble Galdieria sulphuraria protein DCN1 was obtained in greater than 2 mg total synthesis yield per mL of reaction mixture from the Protemist XE, and the structure was subsequently solved by X-ray crystallography using material from one 10 mL synthesis (PDB ID: 3KEV). The Protemist XE was also capable of membrane protein translation. Thus human sigma-1 receptor was translated in the presence of unilamellar liposomes and bacteriorhodopsin was translated directly into detergent micelles in the presence of all-trans-retinal. The versatility, ease of use, and compact size of the Protemist XE robot demonstrate its suitability for large-scale synthesis of many classes of proteins. PMID:20637905

A versatile platform for precise synthesis of asymmetric molecular brush in one shot.

PubMed

Xu, Binbin; Feng, Chun; Huang, Xiaoyu

2017-08-24

Asymmetric molecular brushes emerge as a unique class of nanostructured polymers, while their versatile synthesis keeps a challenge for chemists. Here we show the synthesis of well-defined asymmetric molecular double-brushes comprising two different side chains linked to the same repeat unit along the backbone by one-pot concurrent atom transfer radical polymerization (ATRP) and Cu-catalyzed azide/alkyne cycloaddition (CuAAC) reaction. The double-brushes are based on a poly(Br-acrylate-alkyne) homopolymer possessing an alkynyl for CuAAC reaction and a 2-bromopropionate initiating group for ATRP in each repeat unit. The versatility of this one-shot approach is demonstrated by CuAAC reaction of alkynyl/poly(ethylene oxide)-N 3 and ATRP of various monomers. We also show the quantitative conversion of pentafluorophenyl ester groups to amide groups in side chains, allowing for the further fabrication of diverse building blocks. This work provides a versatile platform for facile synthesis of Janus-type double-brushes with structural and functional control, in a minimum number of reactions.Producing well-defined polymer compositions and structures facilitates their use in many different applications. Here the authors show the synthesis of well-defined asymmetric double-brushes by a one-pot concurrent atom transfer radical polymerization and Cu-catalyzed Click reaction.

Structure of the PSD-95/MAP1A complex reveals a unique target recognition mode of the MAGUK GK domain.

PubMed

Xia, Yitian; Shang, Yuan; Zhang, Rongguang; Zhu, Jinwei

2017-08-10

The PSD-95 family of membrane-associated guanylate kinases (MAGUKs) are major synaptic scaffold proteins and play crucial roles in the dynamic regulation of dendritic remodelling, which is understood to be the foundation of synaptogenesis and synaptic plasticity. The guanylate kinase (GK) domain of MAGUK family proteins functions as a phosphor-peptide binding module. However, the GK domain of PSD-95 has been found to directly bind to a peptide sequence within the C-terminal region of neuronal-specific microtubule-associated protein 1A (MAP1A), although the detailed molecular mechanism governing this phosphorylation-independent interaction at the atomic level is missing. In the present study, we determine the crystal structure of PSD-95 GK in complex with the MAP1A peptide at 2.6-Å resolution. The complex structure reveals that, unlike a linear and elongated conformation in the phosphor-peptide/GK complexes, the MAP1A peptide adopts a unique conformation with a stretch of hydrophobic residues far from each other in the primary sequence clustering and interacting with the 'hydrophobic site' of PSD-95 GK and a highly conserved aspartic acid of MAP1A (D2117) mimicking the phosphor-serine/threonine in binding to the 'phosphor-site' of PSD-95 GK. We demonstrate that the MAP1A peptide may undergo a conformational transition upon binding to PSD-95 GK. Further structural comparison of known DLG GK-mediated complexes reveals the target recognition specificity and versatility of DLG GKs. © 2017 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.

Control of femtosecond laser interference ejection with angle and polarisation

NASA Astrophysics Data System (ADS)

Roper, David M.; Ho, Stephen; Haque, Moez; Herman, Peter R.

2017-03-01

The nonlinear interactions of femtosecond lasers are driving multiple new application directions for nanopatterning and structuring of thin transparent dielectric films that serve in range of technological fields. Fresnel reflections generated by film interfaces were recently shown to confine strong nonlinear interactions at the Fabry-Perot fringe maxima to generate thin nanoscale plasma disks of 20 to 40 nm thickness stacked on half wavelength spacing, λ/2nfilm, inside a film (refractive index, nfilm). The following phase-explosion and ablation dynamics have resulted in a novel means for intrafilm processing that includes `quantized' half-wavelength machining steps and formation of blisters with embedded nanocavities. This paper presents an extension in the control of interferometric laser processing around our past study of Si3N4 and SiOx thin films at 515 nm, 800 nm, and 1044 nm laser wavelengths. The role of laser polarization and incident angle is explored on fringe visibility and improving interferometric processing inside the film to dominate over interface and / or surface ablation. SiOx thin films of 1 μm thickness on silicon substrates were irradiated with a 515 nm wavelength, 280 fs duration laser pulses at 0° to 65° incident angles. A significant transition in ablation region from complete film removal to structured quantized ejection is reported for p- and s-polarised light that is promising to improve control and expand the versatility of the technique to a wider range of applications and materials. The research is aimed at creating novel bio-engineered surfaces for cell culture, bacterial studies and regenerative medicine, and nanofluidic structures that underpin lab-in-a-film. Similarly, the formation of intrafilm blisters and nanocavities offers new opportunities in structuring existing thin film devices, such as CMOS microelectronics, LED, lab-on-chips, and MEMS.

Versatile transfer of aligned carbon nanotubes with polydimethylsiloxane as the intermediate

NASA Astrophysics Data System (ADS)

Zhu, Yanwu; Lim, Xiaodai; Chea Sim, Mong; Teck Lim, Chwee; Haur Sow, Chorng

2008-08-01

A simple technique to transfer aligned multi-walled carbon nanotubes (MWCNTs) is demonstrated in this work. With polydimethylsiloxane (PDMS) as the transfer medium, as-grown or patterned MWCNT arrays are directly transferred onto a wide variety of Pt-coated substrates such as glossy paper, cloth, polymers, glass slides, and metal foils at low temperatures. The surface of the transferred CNTs is cleaner with better alignment, compared with the as-grown one. Furthermore, the transferred CNTs show strong adhesion and good electric contact with the target substrates. A maximal current density of ~104 A cm-2 has been achieved from the CNT interconnects prepared with this technique. Because of the lower density and open-ended structures, improved field emission performance has been obtained from CNTs transferred on polymers, based on which flexible emitter devices can be fabricated. In addition, the surface of transferred CNTs becomes more hydrophilic, with an averaged contact angle of 93.4 ± 5.8°, in contrast to the super-hydrophobic as-grown CNT surface (contact angle 151.6 ± 5.5°). With versatile properties and flexible applications, the technique provides a simple and cost-effective way towards future nanodevices based on CNTs.

Programmable and Bidirectional Bending of Soft Actuators Based on Janus Structure with Sticky Tough PAA-Clay Hydrogel.

PubMed

Zhao, Lei; Huang, Jiahe; Zhang, Yuancheng; Wang, Tao; Sun, Weixiang; Tong, Zhen

2017-04-05

Facile preparation, rapid actuating, and versatile actions are great challenges in exploring new kinds of hydrogel actuators. In this paper, we presented a facile sticking method to prepare Janus bilayer and multilayer hydrogel actuators that benefited from a special tough and adhesive PAA-clay hydrogel. Combining physical and chemical cross-linking reagents, we endowed the PAA gel with both toughness and adhesion. This PAA gel was reinforced by further cross-linking with Fe 3+ . These two hydrogels with different cross-linking densities exhibited different swelling capabilities and moduli in the media manipulated by pH and ionic strength, thus acting as promising candidates for soft actuators. On the basis of these gels, we designed hydrogel actuators of rapid response in several minutes and precisely controlled actuating direction by sticking two hydrogel layers together. Elaborate soft actuators such as bidirectional bending flytrap, gel hand with grasp, open, and gesturing actions as well as word-writing actuator were prepared. This method could be generalized by using other stimuli-responsive hydrogels combined with the adhesive PAA gel, which would open a new way to programmable and versatile soft actuators.

Looking at the Disordered Proteins through the Computational Microscope.

PubMed

Das, Payel; Matysiak, Silvina; Mittal, Jeetain

2018-05-23

Intrinsically disordered proteins (IDPs) have attracted wide interest over the past decade due to their surprising prevalence in the proteome and versatile roles in cell physiology and pathology. A large selection of IDPs has been identified as potential targets for therapeutic intervention. Characterizing the structure-function relationship of disordered proteins is therefore an essential but daunting task, as these proteins can adapt transient structure, necessitating a new paradigm for connecting structural disorder to function. Molecular simulation has emerged as a natural complement to experiments for atomic-level characterizations and mechanistic investigations of this intriguing class of proteins. The diverse range of length and time scales involved in IDP function requires performing simulations at multiple levels of resolution. In this Outlook, we focus on summarizing available simulation methods, along with a few interesting example applications. We also provide an outlook on how these simulation methods can be further improved in order to provide a more accurate description of IDP structure, binding, and assembly.

Large-Scale Noniridescent Structural Color Printing Enabled by Infiltration-Driven Nonequilibrium Colloidal Assembly.

PubMed

Bai, Ling; Mai, Van Cuong; Lim, Yun; Hou, Shuai; Möhwald, Helmuth; Duan, Hongwei

2018-03-01

Structural colors originating from interaction of light with intricately arranged micro-/nanostructures have stimulated considerable interest because of their inherent photostability and energy efficiency. In particular, noniridescent structural color with wide viewing angle has been receiving increasing attention recently. However, no method is yet available for rapid and large-scale fabrication of full-spectrum structural color patterns with wide viewing angles. Here, infiltration-driven nonequilibrium assembly of colloidal particles on liquid-permeable and particle-excluding substrates is demonstrated to direct the particles to form amorphous colloidal arrays (ACAs) within milliseconds. The infiltration-assisted (IFAST) colloidal assembly opens new possibilities for rapid manufacture of noniridescent structural colors of ACAs and straightforward structural color mixing. Full-spectrum noniridescent structural colors are successfully produced by mixing primary structural colors of red, blue, and yellow using a commercial office inkjet printer. Rapid fabrication of large-scale structural color patterns with sophisticated color combination/layout by IFAST printing is realized. The IFAST technology is versatile for developing structural color patterns with wide viewing angles, as colloidal particles, inks, and substrates are flexibly designable for diverse applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Enhancing the versatility of wireless biopotential acquisition for myoelectric prosthetic control.

PubMed

Bercich, Rebecca A; Wang, Zhi; Mei, Henry; Hammer, Lauren H; Seburn, Kevin L; Hargrove, Levi J; Irazoqui, Pedro P

2016-08-01

A significant challenge in rehabilitating upper-limb amputees with sophisticated, electric-powered prostheses is sourcing reliable and independent channels of motor control information sufficient to precisely direct multiple degrees of freedom simultaneously. In response to the expressed needs of clinicians, we have developed a miniature, batteryless recording device that utilizes emerging integrated circuit technology and optimal impedance matching for magnetic resonantly coupled (MRC) wireless power transfer to improve the performance and versatility of wireless electrode interfaces with muscle. In this work we describe the fabrication and performance of a fully wireless and batteryless EMG recording system and use of this system to direct virtual and electric-powered limbs in real-time. The advantage of using MRC to optimize power transfer to a network of wireless devices is exhibited by EMG collected from an array of eight devices placed circumferentially around a human subject's forearm. This is a comprehensive, low-cost, and non-proprietary solution that provides unprecedented versatility of configuration to direct myoelectric prostheses without wired connections to the body. The amenability of MRC to varied coil geometries and arrangements has the potential to improve the efficiency and robustness of wireless power transfer links at all levels of upper-limb amputation. Additionally, the wireless recording device's programmable flash memory and selectable features will grant clinicians the unique ability to adapt and personalize the recording system's functional protocol for patient- or algorithm-specific needs.

Supra-domains: evolutionary units larger than single protein domains.

PubMed

Vogel, Christine; Berzuini, Carlo; Bashton, Matthew; Gough, Julian; Teichmann, Sarah A

2004-02-20

Domains are the evolutionary units that comprise proteins, and most proteins are built from more than one domain. Domains can be shuffled by recombination to create proteins with new arrangements of domains. Using structural domain assignments, we examined the combinations of domains in the proteins of 131 completely sequenced organisms. We found two-domain and three-domain combinations that recur in different protein contexts with different partner domains. The domains within these combinations have a particular functional and spatial relationship. These units are larger than individual domains and we term them "supra-domains". Amongst the supra-domains, we identified some 1400 (1203 two-domain and 166 three-domain) combinations that are statistically significantly over-represented relative to the occurrence and versatility of the individual component domains. Over one-third of all structurally assigned multi-domain proteins contain these over-represented supra-domains. This means that investigation of the structural and functional relationships of the domains forming these popular combinations would be particularly useful for an understanding of multi-domain protein function and evolution as well as for genome annotation. These and other supra-domains were analysed for their versatility, duplication, their distribution across the three kingdoms of life and their functional classes. By examining the three-dimensional structures of several examples of supra-domains in different biological processes, we identify two basic types of spatial relationships between the component domains: the combined function of the two domains is such that either the geometry of the two domains is crucial and there is a tight constraint on the interface, or the precise orientation of the domains is less important and they are spatially separate. Frequently, the role of the supra-domain becomes clear only once the three-dimensional structure is known. Since this is the case for only a quarter of the supra-domains, we provide a list of the most important unknown supra-domains as potential targets for structural genomics projects.

MACF1, versatility in tissue-specific function and in human disease.

PubMed

Hu, Lifang; Xiao, Yunyun; Xiong, Zhipeng; Zhao, Fan; Yin, Chong; Zhang, Yan; Su, Peihong; Li, Dijie; Chen, Zhihao; Ma, Xiaoli; Zhang, Ge; Qian, Airong

2017-09-01

Spectraplakins are a family of evolutionarily conserved gigantic proteins and play critical roles in many cytoskeleton-related processes. Microtubule actin crosslinking factor 1 (MACF1) is one of the most versatile spectraplakin with multiple isoforms. As a broadly expressed mammalian spectraplakin, MACF1 is important in maintaining normal functions of many tissues. The loss-of-function studies using knockout mouse models reveal the pivotal roles of MACF1 in embryo development, skin integrity maintenance, neural development, bone formation, and colonic paracellular permeability. Mutation in the human MACF1 gene causes a novel myopathy genetic disease. In addition, abnormal expression of MACF1 is associated with schizophrenia, Parkinson's disease, cancer and osteoporosis. This demonstrates the crucial roles of MACF1 in physiology and pathology. Here, we review the research advances of MACF1's roles in specific tissue and in human diseases, providing the perspectives of MACF1 for future studies. Copyright © 2017. Published by Elsevier Ltd.

Structure and energetics of hydrogen-bonded networks of methanol on close packed transition metal surfaces

NASA Astrophysics Data System (ADS)

Murphy, Colin J.; Carrasco, Javier; Lawton, Timothy J.; Liriano, Melissa L.; Baber, Ashleigh E.; Lewis, Emily A.; Michaelides, Angelos; Sykes, E. Charles H.

2014-07-01

Methanol is a versatile chemical feedstock, fuel source, and energy storage material. Many reactions involving methanol are catalyzed by transition metal surfaces, on which hydrogen-bonded methanol overlayers form. As with water, the structure of these overlayers is expected to depend on a delicate balance of hydrogen bonding and adsorbate-substrate bonding. In contrast to water, however, relatively little is known about the structures methanol overlayers form and how these vary from one substrate to another. To address this issue, herein we analyze the hydrogen bonded networks that methanol forms as a function of coverage on three catalytically important surfaces, Au(111), Cu(111), and Pt(111), using a combination of scanning tunneling microscopy and density functional theory. We investigate the effect of intermolecular interactions, surface coverage, and adsorption energies on molecular assembly and compare the results to more widely studied water networks on the same surfaces. Two main factors are shown to direct the structure of methanol on the surfaces studied: the surface coverage and the competition between the methanol-methanol and methanol-surface interactions. Additionally, we report a new chiral form of buckled hexamer formed by surface bound methanol that maximizes the interactions between methanol monomers by sacrificing interactions with the surface. These results serve as a direct comparison of interaction strength, assembly, and chirality of methanol networks on Au(111), Cu(111), and Pt(111) which are catalytically relevant for methanol oxidation, steam reforming, and direct methanol fuel cells.

Oleoresin Capsicum has Potential as a Rodent Repellent in Direct Sedding Longleaf Pine

Treesearch

James P. Barnett

1998-01-01

Direct seeding of southern pines has been a versatile and inexpensive alternative to planting on many reforestation sites across the South. Successful direct seeding has required that seeds be coated with thiram to repel birds, and with endrin to repel rodents. Endrin, which is extremely toxic, is no longer produced in the United States. Therefore, a substitute is...

VEGF-independent angiogenic pathways induced by PDGF-C

PubMed Central

Kumar, Anil; Zhang, Fan; Lee, Chunsik; Li, Yang; Tang, Zhongshu; Arjunan, Pachiappan

2010-01-01

VEGF is believed to be a master regulator in both developmental and pathological angiogenesis. The role of PDGF-C in angiogenesis, however, is only at the beginning of being revealed. We and others have shown that PDGF-C is a critical player in pathological angiogenesis because of its pleiotropic effects on multiple cellular targets. The angiogenic pathways induced by PDGF-C are, to a large extent, VEGF-independent. These pathways may include, but not limited to, the direct effect of PDGF-C on vascular cells, the effect of PDGF-C on tissue stroma fibroblasts, and its effect on macrophages. Taken together, the pleiotropic, versatile and VEGF-independent angiogenic nature of PDGF-C has placed it among the most important target genes for antiangiogenic therapy. PMID:20871734

Annealing effect on the structural and dielectric properties of hematite nanoparticles

NASA Astrophysics Data System (ADS)

Kumar, Vijay; Chahal, Surjeet; Singh, Dharamvir; Kumar, Ashok; Kumar, Parmod; Asokan, K.

2018-05-01

In the present work, we have synthesized hematite (α-Fe2O3) nanoparticles by sol-gel method and sintered them at different temperatures (200 °C, 400 °C and 800 °C for six hours). The samples were then characterized using versatile characterization techniques such as X-ray diffraction (XRD), dielectric measurement and temperature dependent resistivity (RT) for their structural, dielectric and electrical properties. XRD measurements infer that intensity of peak increases with an increase in temperature resulting an increase in crystallite size. Temperature dependent resistivity also shows decrease in the resistivity of the samples. Furthermore, the dielectric measurements correspond to the increase in the dielectric constant. Based on these observations, it can be inferred that sintering temperature plays an important role in tailoring the various physical properties of hematite nanoparticles.

Molecular characterization of novel pyridoxal-5'-phosphate-dependent enzymes from the human microbiome.

PubMed

Fleischman, Nicholas M; Das, Debanu; Kumar, Abhinav; Xu, Qingping; Chiu, Hsiu-Ju; Jaroszewski, Lukasz; Knuth, Mark W; Klock, Heath E; Miller, Mitchell D; Elsliger, Marc-André; Godzik, Adam; Lesley, Scott A; Deacon, Ashley M; Wilson, Ian A; Toney, Michael D

2014-08-01

Pyridoxal-5'-phosphate or PLP, the active form of vitamin B6, is a highly versatile cofactor that participates in a large number of mechanistically diverse enzymatic reactions in basic metabolism. PLP-dependent enzymes account for ∼1.5% of most prokaryotic genomes and are estimated to be involved in ∼4% of all catalytic reactions, making this an important class of enzymes. Here, we structurally and functionally characterize three novel PLP-dependent enzymes from bacteria in the human microbiome: two are from Eubacterium rectale, a dominant, nonpathogenic, fecal, Gram-positive bacteria, and the third is from Porphyromonas gingivalis, which plays a major role in human periodontal disease. All adopt the Type I PLP-dependent enzyme fold and structure-guided biochemical analysis enabled functional assignments as tryptophan, aromatic, and probable phosphoserine aminotransferases. © 2014 The Protein Society.

Engineering functionality gradients by dip coating process in acceleration mode.

PubMed

Faustini, Marco; Ceratti, Davide R; Louis, Benjamin; Boudot, Mickael; Albouy, Pierre-Antoine; Boissière, Cédric; Grosso, David

2014-10-08

In this work, unique functional devices exhibiting controlled gradients of properties are fabricated by dip-coating process in acceleration mode. Through this new approach, thin films with "on-demand" thickness graded profiles at the submillimeter scale are prepared in an easy and versatile way, compatible for large-scale production. The technique is adapted to several relevant materials, including sol-gel dense and mesoporous metal oxides, block copolymers, metal-organic framework colloids, and commercial photoresists. In the first part of the Article, an investigation on the effect of the dip coating speed variation on the thickness profiles is reported together with the critical roles played by the evaporation rate and by the viscosity on the fluid draining-induced film formation. In the second part, dip-coating in acceleration mode is used to induce controlled variation of functionalities by playing on structural, chemical, or dimensional variations in nano- and microsystems. In order to demonstrate the full potentiality and versatility of the technique, original graded functional devices are made including optical interferometry mirrors with bidirectional gradients, one-dimensional photonic crystals with a stop-band gradient, graded microfluidic channels, and wetting gradient to induce droplet motion.

Evolutionary versatility of eukaryotic protein domains revealed by their bigram networks

PubMed Central

2011-01-01

Background Protein domains are globular structures of independently folded polypeptides that exert catalytic or binding activities. Their sequences are recognized as evolutionary units that, through genome recombination, constitute protein repertoires of linkage patterns. Via mutations, domains acquire modified functions that contribute to the fitness of cells and organisms. Recent studies have addressed the evolutionary selection that may have shaped the functions of individual domains and the emergence of particular domain combinations, which led to new cellular functions in multi-cellular animals. This study focuses on modeling domain linkage globally and investigates evolutionary implications that may be revealed by novel computational analysis. Results A survey of 77 completely sequenced eukaryotic genomes implies a potential hierarchical and modular organization of biological functions in most living organisms. Domains in a genome or multiple genomes are modeled as a network of hetero-duplex covalent linkages, termed bigrams. A novel computational technique is introduced to decompose such networks, whereby the notion of domain "networking versatility" is derived and measured. The most and least "versatile" domains (termed "core domains" and "peripheral domains" respectively) are examined both computationally via sequence conservation measures and experimentally using selected domains. Our study suggests that such a versatility measure extracted from the bigram networks correlates with the adaptivity of domains during evolution, where the network core domains are highly adaptive, significantly contrasting the network peripheral domains. Conclusions Domain recombination has played a major part in the evolution of eukaryotes attributing to genome complexity. From a system point of view, as the results of selection and constant refinement, networks of domain linkage are structured in a hierarchical modular fashion. Domains with high degree of networking versatility appear to be evolutionary adaptive, potentially through functional innovations. Domain bigram networks are informative as a model of biological functions. The networking versatility indices extracted from such networks for individual domains reflect the strength of evolutionary selection that the domains have experienced. PMID:21849086

Evolutionary versatility of eukaryotic protein domains revealed by their bigram networks.

PubMed

Xie, Xueying; Jin, Jing; Mao, Yongyi

2011-08-18

Protein domains are globular structures of independently folded polypeptides that exert catalytic or binding activities. Their sequences are recognized as evolutionary units that, through genome recombination, constitute protein repertoires of linkage patterns. Via mutations, domains acquire modified functions that contribute to the fitness of cells and organisms. Recent studies have addressed the evolutionary selection that may have shaped the functions of individual domains and the emergence of particular domain combinations, which led to new cellular functions in multi-cellular animals. This study focuses on modeling domain linkage globally and investigates evolutionary implications that may be revealed by novel computational analysis. A survey of 77 completely sequenced eukaryotic genomes implies a potential hierarchical and modular organization of biological functions in most living organisms. Domains in a genome or multiple genomes are modeled as a network of hetero-duplex covalent linkages, termed bigrams. A novel computational technique is introduced to decompose such networks, whereby the notion of domain "networking versatility" is derived and measured. The most and least "versatile" domains (termed "core domains" and "peripheral domains" respectively) are examined both computationally via sequence conservation measures and experimentally using selected domains. Our study suggests that such a versatility measure extracted from the bigram networks correlates with the adaptivity of domains during evolution, where the network core domains are highly adaptive, significantly contrasting the network peripheral domains. Domain recombination has played a major part in the evolution of eukaryotes attributing to genome complexity. From a system point of view, as the results of selection and constant refinement, networks of domain linkage are structured in a hierarchical modular fashion. Domains with high degree of networking versatility appear to be evolutionary adaptive, potentially through functional innovations. Domain bigram networks are informative as a model of biological functions. The networking versatility indices extracted from such networks for individual domains reflect the strength of evolutionary selection that the domains have experienced.

Origami-inspired, on-demand deployable and collapsible mechanical metamaterials with tunable stiffness

NASA Astrophysics Data System (ADS)

Zhai, Zirui; Wang, Yong; Jiang, Hanqing

2018-03-01

Origami has been employed to build deployable mechanical metamaterials through folding and unfolding along the crease lines. Deployable metamaterials are usually flexible, particularly along their deploying and collapsing directions, which unfortunately in many cases leads to an unstable deployed state, i.e., small perturbations may collapse the structure along the same deployment path. Here we create an origami-inspired mechanical metamaterial with on-demand deployability and selective collapsibility through energy analysis. This metamaterial has autonomous deployability from the collapsed state and can be selectively collapsed along two different paths, embodying low stiffness for one path and substantially high stiffness for another path. The created mechanical metamaterial yields load-bearing capability in the deployed direction while possessing great deployability and collapsibility. The principle in this work can be utilized to design and create versatile origami-inspired mechanical metamaterials that can find many applications.

Origami-inspired, on-demand deployable and collapsible mechanical metamaterials with tunable stiffness.

PubMed

Zhai, Zirui; Wang, Yong; Jiang, Hanqing

2018-02-27

Origami has been employed to build deployable mechanical metamaterials through folding and unfolding along the crease lines. Deployable metamaterials are usually flexible, particularly along their deploying and collapsing directions, which unfortunately in many cases leads to an unstable deployed state, i.e., small perturbations may collapse the structure along the same deployment path. Here we create an origami-inspired mechanical metamaterial with on-demand deployability and selective collapsibility through energy analysis. This metamaterial has autonomous deployability from the collapsed state and can be selectively collapsed along two different paths, embodying low stiffness for one path and substantially high stiffness for another path. The created mechanical metamaterial yields load-bearing capability in the deployed direction while possessing great deployability and collapsibility. The principle in this work can be utilized to design and create versatile origami-inspired mechanical metamaterials that can find many applications. Copyright © 2018 the Author(s). Published by PNAS.

Origami-inspired, on-demand deployable and collapsible mechanical metamaterials with tunable stiffness

PubMed Central

Zhai, Zirui; Wang, Yong

2018-01-01

Origami has been employed to build deployable mechanical metamaterials through folding and unfolding along the crease lines. Deployable metamaterials are usually flexible, particularly along their deploying and collapsing directions, which unfortunately in many cases leads to an unstable deployed state, i.e., small perturbations may collapse the structure along the same deployment path. Here we create an origami-inspired mechanical metamaterial with on-demand deployability and selective collapsibility through energy analysis. This metamaterial has autonomous deployability from the collapsed state and can be selectively collapsed along two different paths, embodying low stiffness for one path and substantially high stiffness for another path. The created mechanical metamaterial yields load-bearing capability in the deployed direction while possessing great deployability and collapsibility. The principle in this work can be utilized to design and create versatile origami-inspired mechanical metamaterials that can find many applications. PMID:29440441

Versatile retraction mechanics: Implant assisted en-masse retraction with a boot loop.

PubMed

Philip, Pramod; Jose, Nidhin Philip

2015-03-01

The purpose of this paper is to explain the versatility offered by the use of arch wires with boot loops in retraction mechanics while taking direct anchorage from mini-screws. The materials include the mini screws placed at the appropriate location and retraction arches made of 0.019 X 0.025 SS with boot loops placed distal to the lateral incisors. Mini screw provides a stable anchorage for enmasse retraction of the anterior teeth with the help of a boot loop using sliding and/or loop mechanics. The arch wires with boot loops have a definite advantage over the soldered/crimpable hooks because of the versatility it offers during the process of retraction. An innovative approach combining the advantages of absolute anchorage using mini implants and a retraction arch with boot loop is presented here.

The ‘LipoYeasts’ project: using the oleaginous yeast Yarrowia lipolytica in combination with specific bacterial genes for the bioconversion of lipids, fats and oils into high‐value products

PubMed Central

Sabirova, Julia S.; Haddouche, R.; Van Bogaert, I. N.; Mulaa, F.; Verstraete, W.; Timmis, K. N.; Schmidt‐Dannert, C.; Nicaud, J. M.; Soetaert, W.

2011-01-01

Summary The oleochemical industry is currently still dominated by conventional chemistry, with biotechnology only starting to play a more prominent role, primarily with respect to the biosurfactants or lipases, e.g. as detergents, or for biofuel production. A major bottleneck for all further biotechnological applications is the problem of the initial mobilization of cheap and vastly available lipid and oil substrates, which are then to be transformed into high‐value biotechnological, nutritional or pharmacological products. Under the EU‐sponsored LipoYeasts project we are developing the oleaginous yeast Yarrowia lipolytica into a versatile and high‐throughput microbial factory that, by use of specific enzymatic pathways from hydrocarbonoclastic bacteria, efficiently mobilizes lipids by directing its versatile lipid metabolism towards the production of industrially valuable lipid‐derived compounds like wax esters (WE), isoprenoid‐derived compounds (carotenoids, polyenic carotenoid ester), polyhydroxyalkanoates (PHAs) and free hydroxylated fatty acids (HFAs). Different lipid stocks (petroleum, alkane, vegetable oil, fatty acid) and combinations thereof are being assessed as substrates in combination with different mutant and recombinant strains of Y. lipolytica, in order to modulate the composition and yields of the produced added‐value products. PMID:21255371

A single molecule assay to probe monovalent and multivalent bonds between hyaluronan and its key leukocyte receptor CD44 under force

NASA Astrophysics Data System (ADS)

Bano, Fouzia; Banerji, Suneale; Howarth, Mark; Jackson, David G.; Richter, Ralf P.

2016-09-01

Glycosaminoglycans (GAGs), a category of linear, anionic polysaccharides, are ubiquitous in the extracellular space, and important extrinsic regulators of cell function. Despite the recognized significance of mechanical stimuli in cellular communication, however, only few single molecule methods are currently available to study how monovalent and multivalent GAG·protein bonds respond to directed mechanical forces. Here, we have devised such a method, by combining purpose-designed surfaces that afford immobilization of GAGs and receptors at controlled nanoscale organizations with single molecule force spectroscopy (SMFS). We apply the method to study the interaction of the GAG polymer hyaluronan (HA) with CD44, its receptor in vascular endothelium. Individual bonds between HA and CD44 are remarkably resistant to rupture under force in comparison to their low binding affinity. Multiple bonds along a single HA chain rupture sequentially and independently under load. We also demonstrate how strong non-covalent bonds, which are versatile for controlled protein and GAG immobilization, can be effectively used as molecular anchors in SMFS. We thus establish a versatile method for analyzing the nanomechanics of GAG·protein interactions at the level of single GAG chains, which provides new molecular-level insight into the role of mechanical forces in the assembly and function of GAG-rich extracellular matrices.

The Silent Revolution Continues.

ERIC Educational Resources Information Center

Perlin, John

2001-01-01

Discusses the reliability and versatility of using photovoltaics whereby solar cells convert sunlight directly into electricity. The growing concern of global warming promises to transform photovoltaics into a major energy producer. (Author/SAH)

Design of SOI wavelength filter based on multiple MMIs structures

NASA Astrophysics Data System (ADS)

Hu, Youfang; Gardes, Frédéric Y.; Jenkins, Richard M.; Finlayson, Ewan D.; Mashanovich, Goran Z.; Reed, Graham T.

2011-01-01

SOI based MMIs prove to be versatile photonic structures for optical power splitting/combining, directional coupling, wavelength multiplexing/demultiplexing, etc. Such a structure benefits from relative ease of fabrication, low sensitivity to fabrication error and low temperature dependence. Whilst the majority of previous designs and optimizations investigated single MMIs, there is significant potential to combine MMIs within a single device for the realization of improved device performance. We have designed and simulated a wavelength filter device consisting of a series of MMIs with different lengths. The bandwidth, free spectral range, and extinction ratio can be controlled by changing the MMI's width and length. We have optimized our design to achieve a -3dB bandwidth of 5nm, a free spectral range of 60nm, an extinction ratio of >30dB, and a side peak suppression ratio of >22dB. Such a device can be used for high performance coarse wavelength filtering. The whole structure can fit into a 70μm×300μm area. Temperature sensitivity of the designed structures was also investigated.

Genomic analysis reveals versatile heterotrophic capacity of a potentially symbiotic sulfur-oxidizing bacterium in sponge.

PubMed

Tian, Ren-Mao; Wang, Yong; Bougouffa, Salim; Gao, Zhao-Ming; Cai, Lin; Bajic, Vladimir; Qian, Pei-Yuan

2014-11-01

Sulfur-reducing bacteria (SRB) and sulfur-oxidizing bacteria (SOB) play essential roles in marine sponges. However, the detailed characteristics and physiology of the bacteria are largely unknown. Here, we present and analyse the first genome of sponge-associated SOB using a recently developed metagenomic binning strategy. The loss of transposase and virulence-associated genes and the maintenance of the ancient polyphosphate glucokinase gene suggested a stabilized SOB genome that might have coevolved with the ancient host during establishment of their association. Exclusive distribution in sponge, bacterial detoxification for the host (sulfide oxidation) and the enrichment for symbiotic characteristics (genes-encoding ankyrin) in the SOB genome supported the bacterial role as an intercellular symbiont. Despite possessing complete autotrophic sulfur oxidation pathways, the bacterium developed a much more versatile capacity for carbohydrate uptake and metabolism, in comparison with its closest relatives (Thioalkalivibrio) and to other representative autotrophs from the same order (Chromatiales). The ability to perform both autotrophic and heterotrophic metabolism likely results from the unstable supply of reduced sulfur in the sponge and is considered critical for the sponge-SOB consortium. Our study provides insights into SOB of sponge-specific clade with thioautotrophic and versatile heterotrophic metabolism relevant to its roles in the micro-environment of the sponge body. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.

On the versatility of electronic structures in polymethine dyes

NASA Astrophysics Data System (ADS)

Pascal, Simon; Haefele, Alexandre; Monnereau, Cyrille; Charaf-Eddin, Azzam; Jacquemin, Denis; Le Guennic, Boris; Maury, Olivier; Andraud, Chantal

2014-10-01

This article provides an overview of the photophysical behavior diversity of polymethine chromophores which are ubiquitous in biological imaging and material sciences. One major challenge in this class of chromophore is to correlate the chemical structure to the observed optical properties, especially when symmetry-breaking phenomena occur. With the constant concern for rationalization of their spectroscopy, we propose an extended classification of polymethine dyes based on their ground state electronic configuration using three limit forms namely: cyanine, dipole and bis-dipole. The chemical modifications of the dye and the influence of exogenous parameters can promote dramatic spectroscopic changes that can be correlated to significant electronic reorganization between the three-abovementioned forms. The deep understanding of such phenomena should allow to identify, predict and take advantage of the versatile electronic structure of polymethines.

Two-Dimensional Stoichiometric Boron Oxides as a Versatile Platform for Electronic Structure Engineering.

PubMed

Zhang, Ruiqi; Li, Zhenyu; Yang, Jinlong

2017-09-21

Oxides of two-dimensional (2D) atomic crystals have been widely studied due to their unique properties. In most 2D oxides, oxygen acts as a functional group, which makes it difficult to control the degree of oxidation. Because borophene is an electron-deficient system, it is expected that oxygen will be intrinsically incorporated into the basal plane of borophene, forming stoichiometric 2D boron oxide (BO) structures. By using first-principles global optimization, we systematically explore structures and properties of 2D BO systems with well-defined degrees of oxidation. Stable B-O-B and OB 3 tetrahedron structure motifs are identified in these structures. Interesting properties, such as strong linear dichroism, Dirac node-line (DNL) semimetallicity, and negative differential resistance, have been predicted for these systems. Our results demonstrate that 2D BO represents a versatile platform for electronic structure engineering via tuning the stoichiometric degree of oxidation, which leads to various technological applications.

Direct amination of γ-halo-β-ketoesters with anilines

PubMed Central

Zhang, Yinan; Silverman, Richard B.

2012-01-01

The direct amination of α-haloacetoacetates with anilines is described. Compared to existing methods, this simple protocol provides an attractive strategy to prepare diverse γ-anilino-β-ketoesters in one step. Good to excellent yields of the amination products were obtained under robust conditions, providing versatile and useful scaffolds. PMID:22390154

Direct-seedling pines in the south

Treesearch

Harold J. Derr; William F. Mann

1971-01-01

Direct seeding of the southern pines is a versatile reforestation technique that is being widely accepted by land managers. On many sites it is more economical than planting nursery-grown seedlings or waiting for natural reproduction. It is applicable on some sites where access, terrain, or drainage conditions make planting difficult. Commercial trials have proved it...

Development of deployable structures for large space platform systems, part 1

NASA Technical Reports Server (NTRS)

Cox, R. L.; Nelson, R. A.

1982-01-01

Eight deployable platform design objectives were established: autodeploy/retract; fully integrated utilities; configuration variability; versatile payload and subsystem interfaces; structural and packing efficiency; 1986 technology readiness; minimum EVA/RMS; and Shuttle operational compatibility.

Penicillium spp.: prolific producer for harnessing cytotoxic secondary metabolites.

PubMed

Koul, Mytre; Singh, Shashank

2017-01-01

Secondary metabolites from fungal endophytes have become an interesting, attractive, and alternative source for novel pharmaceuticals. Several novel compounds with diversified chemical structures have been isolated from endophytic fungi. The genus Penicillium has been exploited worldwide for its biosynthetic potential for producing highly versatile cytotoxic secondary metabolites. Many of the compounds isolated from various species of the genus Penicillium have shown promising in-vitro as well as in-vivo growth-inhibitory properties against different human cancers. Thus, in relation to this genus, Penicillium represents the most dependable source of cytotoxic compounds with potential applications as leads for anticancer drugs. This review outlines endophytic secondary metabolites from the genus Penicillium with a relevant role as cytotoxic agents.

Emergence and transitions of dynamic patterns of thickness oscillation of the plasmodium of the true slime mold Physarum polycephalum

NASA Astrophysics Data System (ADS)

Takagi, Seiji; Ueda, Tetsuo

2008-03-01

The emergence and transitions of various spatiotemporal patterns of thickness oscillation were studied in the freshly isolated protoplasm of the Physarum plasmodium. New patterns, such as standing waves, and chaotic and rotating spirals, developed successively before the well-documented synchronous pattern appeared. There was also a spontaneous opposite transition from synchrony to chaotic and rotating spirals. Rotating spiral waves were observed in the large migrating plasmodium, where the vein structures were being destroyed. Thus, the Physarum plasmodium exhibits versatile patterns, which are generally expected in coupled oscillator systems. This paper discusses the physiological roles of spatiotemporal patterns, comparing them with other biological systems.

Sequence features associated with the cleavage efficiency of CRISPR/Cas9 system.

PubMed

Liu, Xiaoxi; Homma, Ayaka; Sayadi, Jamasb; Yang, Shu; Ohashi, Jun; Takumi, Toru

2016-01-27

The CRISPR-Cas9 system has recently emerged as a versatile tool for biological and medical research. In this system, a single guide RNA (sgRNA) directs the endonuclease Cas9 to a targeted DNA sequence for site-specific manipulation. In addition to this targeting function, the sgRNA has also been shown to play a role in activating the endonuclease activity of Cas9. This dual function of the sgRNA likely underlies observations that different sgRNAs have varying on-target activities. Currently, our understanding of the relationship between sequence features of sgRNAs and their on-target cleavage efficiencies remains limited, largely due to difficulties in assessing the cleavage capacity of a large number of sgRNAs. In this study, we evaluated the cleavage activities of 218 sgRNAs using in vitro Surveyor assays. We found that nucleotides at both PAM-distal and PAM-proximal regions of the sgRNA are significantly correlated with on-target efficiency. Furthermore, we also demonstrated that the genomic context of the targeted DNA, the GC percentage, and the secondary structure of sgRNA are critical factors contributing to cleavage efficiency. In summary, our study reveals important parameters for the design of sgRNAs with high on-target efficiencies, especially in the context of high throughput applications.

Controllable synthesis of palladium nanocubes/reduced graphene oxide composites and their enhanced electrocatalytic performance

NASA Astrophysics Data System (ADS)

Zhang, Yuting; Huang, Qiwei; Chang, Gang; Zhang, Zaoli; Xia, Tiantian; Shu, Honghui; He, Yunbin

2015-04-01

Homogeneous distribution of cube-shaped Pd nanocrystals on the surface of reduced graphene oxide is obtained via a facile one-step method by employing AA and KBr as the reductant and capping agent, respectively. The experimental factors affecting the morphology and structure of Pd nanoparticles have been systematically investigated to explore the formation mechanism of Pd nanocubes (PdNCs). It is revealed that PdNCs enclosed by active {100} facets with an average side length of 15 nm were successfully synthesized on the surface of reduced graphene oxide. KBr plays the role for facet selection by surface passivation and AA controls the reduction speed of Pd precursors, both of which govern the morphology changes of palladium nanoparticles. In the further electrochemical evaluations, the Pd nanocubes/reduced graphene oxide composites show better electrocatalytic activity and stability towards the electro-oxidation of ethanol than both reduced graphene oxide supported Pd nanoparticles and free-standing PdNCs. It could be attributed to the high electrocatalytic activity of the dominated active {100} crystal facets of Pd nanocubes and the enhanced electron transfer of graphene. The developed approach provide a versatile way for shape-controlled preparation of noble metal nanoparticles, which can work as novel electrocatalysts in the application of direct alcohols fuel cells.

Fabrication of Superhydrophobic Surfaces with Controllable Electrical Conductivity and Water Adhesion.

PubMed

Ye, Lijun; Guan, Jipeng; Li, Zhixiang; Zhao, Jingxin; Ye, Cuicui; You, Jichun; Li, Yongjin

2017-02-14

A facile and versatile strategy for fabricating superhydrophobic surfaces with controllable electrical conductivity and water adhesion is reported. "Vine-on-fence"-structured and cerebral cortex-like superhydrophobic surfaces are constructed by filtering a suspension of multiwalled carbon nanotubes (MWCNTs), using polyoxymethylene nonwovens as the filter paper. The nonwovens with micro- and nanoporous two-tier structures act as the skeleton, introducing a microscale structure. The MWCNTs act as nanoscale structures, creating hierarchical surface roughness. The surface topography and the electrical conductivity of the superhydrophobic surfaces are controlled by varying the MWCNT loading. The vine-on-fence-structured surfaces exhibit "sticky" superhydrophobicity with high water adhesion. The cerebral cortex-like surfaces exhibit self-cleaning properties with low water adhesion. The as-prepared superhydrophobic surfaces are chemically resistant to acidic and alkaline environments of pH 2-12. They therefore have potential in applications such as droplet-based microreactors and thin-film microextraction. These findings aid our understanding of the role that surface topography plays in the design and fabrication of superhydrophobic surfaces with different water-adhesion properties.

Crystal structures of botulinum neurotoxin DC in complex with its protein receptors synaptotagmin I and II.

PubMed

Berntsson, Ronnie Per-Arne; Peng, Lisheng; Svensson, Linda Marie; Dong, Min; Stenmark, Pål

2013-09-03

Botulinum neurotoxins (BoNTs) can cause paralysis at exceptionally low concentrations and include seven serotypes (BoNT/A-G). The chimeric BoNT/DC toxin has a receptor binding domain similar to the same region in BoNT/C. However, BoNT/DC does not share protein receptor with BoNT/C. Instead, it shares synaptotagmin (Syt) I and II as receptors with BoNT/B, despite their low sequence similarity. Here, we present the crystal structures of the binding domain of BoNT/DC in complex with the recognition domains of its protein receptors, Syt-I and Syt-II. The structures reveal that BoNT/DC possesses a Syt binding site, distinct from the established Syt-II binding site in BoNT/B. Structure-based mutagenesis further shows that hydrophobic interactions play a key role in Syt binding. The structures suggest that the BoNT/DC ganglioside binding sites are independent of the protein receptor binding site. Our results reveal the remarkable versatility in the receptor recognition of the BoNTs. Copyright © 2013 Elsevier Ltd. All rights reserved.

Membrane remodeling by amyloidogenic and non-amyloidogenic proteins studied by EPR

NASA Astrophysics Data System (ADS)

Varkey, Jobin; Langen, Ralf

2017-07-01

The advancement in site-directed spin labeling of proteins has enabled EPR studies to expand into newer research areas within the umbrella of protein-membrane interactions. Recently, membrane remodeling by amyloidogenic and non-amyloidogenic proteins has gained a substantial interest in relation to driving and controlling vital cellular processes such as endocytosis, exocytosis, shaping of organelles like endoplasmic reticulum, Golgi and mitochondria, intracellular vesicular trafficking, formation of filopedia and multivesicular bodies, mitochondrial fusion and fission, and synaptic vesicle fusion and recycling in neurotransmission. Misregulation in any of these processes due to an aberrant protein (mutation or misfolding) or alteration of lipid metabolism can be detrimental to the cell and cause disease. Dissection of the structural basis of membrane remodeling by proteins is thus quite necessary for an understanding of the underlying mechanisms, but it remains a formidable task due to the difficulties of various common biophysical tools in monitoring the dynamic process of membrane binding and bending by proteins. This is largely since membranes generally complicate protein structure analysis and this problem is amplified for structural analysis in the presence of different types of membrane curvatures. Recent EPR studies on membrane remodeling by proteins show that a significant structural information can be generated to delineate the role of different protein modules, domains and individual amino acids in the generation of membrane curvature. These studies also show how EPR can complement the data obtained by high resolution techniques such as X-ray and NMR. This perspective covers the application of EPR in recent studies for understanding membrane remodeling by amyloidogenic and non-amyloidogenic proteins that is useful for researchers interested in using or complimenting EPR to gain better understanding of membrane remodeling. We also discuss how a single protein can generate different type of membrane curvatures using specific conformations for specific membrane structures and how EPR is a versatile tool well-suited to analyze subtle alterations in structures under such modifying conditions which otherwise would have been difficult using other biophysical tools.

A versatile approach to the study of the transient response of a submerged thin shell

NASA Astrophysics Data System (ADS)

Leblond, C.; Sigrist, J.-F.

2010-01-01

The transient response of submerged two-dimensional thin shell subjected to weak acoustical or mechanical excitations is addressed in this paper. The proposed approach is first exposed in a detailed manner: it is based on Laplace transform in time, in vacuo eigenvector expansion with time-dependent coefficients for the structural dynamics and boundary-integral formulation for the fluid. The projection of the fluid pressure on the in vacuo eigenvectors leads to a fully coupled system involving the modal time-dependent displacement coefficients, which are the problem unknowns. They are simply determined by matrix inversion in the Laplace domain. Application of the method to the response of a two-dimensional immersed shell to a weak acoustical excitation is then exposed: the proposed test-case corresponds to the design of immersed structures subjected to underwater explosions, which is of paramount importance in naval shipbuilding. Comparison of a numerical calculation based on the proposed approach with an analytical solution is exposed; versatility of the method is also highlighted by referring to "classical" FEM/FEM or FEM/BEM simulations. As a conspicuous feature of the method, calculation of the fluid response functions corresponding to a given geometry has to be performed once, allowing various simulations for different material properties of the structure, as well as for various excitations on the structure. This versatile approach can therefore be efficiently and extensively used for design purposes.

The Development Process of eHealth Strategy for Nurses in Finland.

PubMed

Ahonen, Outi; Kouri, Pirkko; Kinnunen, Ulla-Mari; Junttila, Kristiina; Liljamo, Pia; Arifulla, Dinah; Saranto, Kaija

2016-01-01

Growing use of information and communication technology (ICT) demands have caused a need for nursing to strengthen the knowledge, skills and competences related to ICT in health (eHealth) and define its versatile roles. The Finnish Nurses Association (FNA) named a group of eHealth experts from various professional fields that are closely connected to nursing e.g. nursing practice, higher education, nursing research and administration. The main purpose was to describe nurses' contribution to the national strategy concerning eHealth development and implementation in health and social care. The group searched for answers, discussed strategic issues, wrote drafts, and sent texts for open commentary circles. The chosen themes of the eHealth strategies deal with the role of the client, nursing practice, ethical aspects education and eHealth competences, nursing leadership, knowledge management and research and development. The article describes the strategic work and the structure of eHealth strategy of nurses in Finland.

Cardiovascular Magnetic Resonance in Cardiology Practice: A Concise Guide to Image Acquisition and Clinical Interpretation.

PubMed

Valbuena-López, Silvia; Hinojar, Rocío; Puntmann, Valentina O

2016-02-01

Cardiovascular magnetic resonance plays an increasingly important role in routine cardiology clinical practice. It is a versatile imaging modality that allows highly accurate, broad and in-depth assessment of cardiac function and structure and provides information on pertinent clinical questions in diseases such as ischemic heart disease, nonischemic cardiomyopathies, and heart failure, as well as allowing unique indications, such as the assessment and quantification of myocardial iron overload or infiltration. Increasing evidence for the role of cardiovascular magnetic resonance, together with the spread of knowledge and skill outside expert centers, has afforded greater access for patients and wider clinical experience. This review provides a snapshot of cardiovascular magnetic resonance in modern clinical practice by linking image acquisition and postprocessing with effective delivery of the clinical meaning. Copyright © 2015 Sociedad Española de Cardiología. Published by Elsevier España, S.L.U. All rights reserved.

Label-Free Direct Electronic Detection of Biomolecules with Amorphous Silicon Nanostructures

PubMed Central

Lund, John; Mehta, Ranjana; Parviz, Babak A.

2007-01-01

We present the fabrication and characterization of a nano-scale sensor made of amorphous silicon for the label-free, electronic detection of three classes of biologically important molecules: ions, oligonucleotides, and proteins. The sensor structure has an active element which is a 50 nm wide amorphous silicon semicircle and has a total footprint of less than 4 μm2. We demonstrate the functionalization of the sensor with receptor molecules and the electronic detection of three targets: H+ ions, short single-stranded DNAs, and streptavidin. The sensor is able to reliably distinguish single base-pair mismatches in 12 base long strands of DNA and monitor the introduction and identification of straptavidin in real-time. The versatile sensor structure can be readily functionalized with a wide range of receptor molecules and is suitable for integration with high-speed electronic circuits as a post-process on an integrated circuit chip. PMID:17292148

Synthesis of nanostructures in nanowires using sequential catalyst reactions

DOE PAGES

Panciera, F.; Chou, Y. -C.; Reuter, M. C.; ...

2015-07-13

Nanowire growth by the vapour–liquid–solid (VLS) process enables a high level of control over nanowire composition, diameter, growth direction, branching and kinking, periodic twinning, and crystal structure. The tremendous impact of VLS-grown nanowires is due to this structural versatility, generating applications ranging from solid-state lighting and single-photon sources to thermoelectric devices. Here, we show that the morphology of these nanostructures can be further tailored by using the liquid droplets that catalyse nanowire growth as a ‘mixing bowl’, in which growth materials are sequentially supplied to nucleate new phases. Growing within the liquid, these phases adopt the shape of faceted nanocrystalsmore » that are then incorporated into the nanowires by further growth. Furthermore, we demonstrate this concept by epitaxially incorporating metal-silicide nanocrystals into Si nanowires with defect-free interfaces, and discuss how this process can be generalized to create complex nanowire-based heterostructures.« less

Three-Component Soliton States in Spinor F =1 Bose-Einstein Condensates

NASA Astrophysics Data System (ADS)

Bersano, T. M.; Gokhroo, V.; Khamehchi, M. A.; D'Ambroise, J.; Frantzeskakis, D. J.; Engels, P.; Kevrekidis, P. G.

2018-02-01

Dilute-gas Bose-Einstein condensates are an exceptionally versatile test bed for the investigation of novel solitonic structures. While matter-wave solitons in one- and two-component systems have been the focus of intense research efforts, an extension to three components has never been attempted in experiments. Here, we experimentally demonstrate the existence of robust dark-bright-bright (DBB) and dark-dark-bright solitons in a multicomponent F =1 condensate. We observe lifetimes on the order of hundreds of milliseconds for these structures. Our theoretical analysis, based on a multiscale expansion method, shows that small-amplitude solitons of these types obey universal long-short wave resonant interaction models, namely, Yajima-Oikawa systems. Our experimental and analytical findings are corroborated by direct numerical simulations highlighting the persistence of, e.g., the DBB soliton states, as well as their robust oscillations in the trap.

Three-Component Soliton States in Spinor F=1 Bose-Einstein Condensates.

PubMed

Bersano, T M; Gokhroo, V; Khamehchi, M A; D'Ambroise, J; Frantzeskakis, D J; Engels, P; Kevrekidis, P G

2018-02-09

Dilute-gas Bose-Einstein condensates are an exceptionally versatile test bed for the investigation of novel solitonic structures. While matter-wave solitons in one- and two-component systems have been the focus of intense research efforts, an extension to three components has never been attempted in experiments. Here, we experimentally demonstrate the existence of robust dark-bright-bright (DBB) and dark-dark-bright solitons in a multicomponent F=1 condensate. We observe lifetimes on the order of hundreds of milliseconds for these structures. Our theoretical analysis, based on a multiscale expansion method, shows that small-amplitude solitons of these types obey universal long-short wave resonant interaction models, namely, Yajima-Oikawa systems. Our experimental and analytical findings are corroborated by direct numerical simulations highlighting the persistence of, e.g., the DBB soliton states, as well as their robust oscillations in the trap.

Novel solution-phase structures of gallium-containing pyrogallol[4]arene scaffolds**

PubMed Central

Kumari, Harshita; Kline, Steven R.; Wycoff, Wei G.; Paul, Rick L.; Mossine, Andrew V.; Deakyne, Carol A.; Atwood, Jerry L.

2012-01-01

The variations in architecture of gallium-seamed (PgC4Ga) and gallium-zinc-seamed (PgC4GaZn) C-butylpyrogallol[4]arene nanoassemblies in solution (SANS/NMR) versus the solid state (XRD) have been investigated. Rearrangement from the solid-state spheroidal to the solution-phase toroidal shape differentiates the gallium-containing pyrogallol[4]arene nanoassemblies from all other PgCnM nanocapsules studied thus far. Different structural arrangements of the metals and arenes of PgC4Ga versus PgC4GaZn have been deduced from the different toroidal dimensions, C–H proton environments and guest encapsulation of the two toroids. PGAA of mixed-metal hexamers reveals a decrease in gallium-to-metal ratio as the second metal varies from cobalt to zinc. Overall, the combined study demonstrates the versatility of gallium in directing the self-assembly of pyrogallol[4]arenes into novel nanoarchitectures. PMID:22511521

Study of Different Sol-Gel Coatings to Enhance the Lifetime of PDMS Devices: Evaluation of Their Biocompatibility.

PubMed

Aymerich, María; Gómez-Varela, Ana I; Álvarez, Ezequiel; Flores-Arias, María T

2016-08-25

A study of PDMS (polydimethylsiloxane) sol-gel-coated channels fabricated using soft lithography and a laser direct writing technique is presented. PDMS is a biocompatible material that presents a high versatility to reproduce several structures. It is widely employed in the fabrication of preclinical devices due to its advantages but it presents a rapid chemical deterioration to organic solvents. The use of sol-gel layers to cover the PDMS overcomes this problem since it provides the robustness of glass for the structures made with PDMS, decreasing its deterioration and changing the biocompatibility of the surface. In this work, PDMS channels are coated with three different kinds of sol-gel compositions (60MTES/40TEOS, 70MTES/30TISP and 80MTES/20TISP). The endothelial cell adhesion to the different coated devices is evaluated in order to determine the most suitable sol-gel preparation conditions to enhance cellular adhesion.

Nanomechanical DNA origami 'single-molecule beacons' directly imaged by atomic force microscopy

PubMed Central

Kuzuya, Akinori; Sakai, Yusuke; Yamazaki, Takahiro; Xu, Yan; Komiyama, Makoto

2011-01-01

DNA origami involves the folding of long single-stranded DNA into designed structures with the aid of short staple strands; such structures may enable the development of useful nanomechanical DNA devices. Here we develop versatile sensing systems for a variety of chemical and biological targets at molecular resolution. We have designed functional nanomechanical DNA origami devices that can be used as 'single-molecule beacons', and function as pinching devices. Using 'DNA origami pliers' and 'DNA origami forceps', which consist of two levers ~170 nm long connected at a fulcrum, various single-molecule inorganic and organic targets ranging from metal ions to proteins can be visually detected using atomic force microscopy by a shape transition of the origami devices. Any detection mechanism suitable for the target of interest, pinching, zipping or unzipping, can be chosen and used orthogonally with differently shaped origami devices in the same mixture using a single platform. PMID:21863016

Fabrication of reduced graphene oxide nanosheets doped PVA composite films for tailoring their opto-mechanical properties

NASA Astrophysics Data System (ADS)

Aslam, Muhammad; Kalyar, Mazhar Ali; Raza, Zulfiqar Ali

2017-06-01

Laminar graphene nanosheets have raised passionate attention due to their incredible physico-chemical properties. Its wide-scale, high-yield production at low-cost has made it possible to produce top class promising versatile polymer nanocomposites. Reduced graphene oxide (RGO) nanosheets were incorporated to prepare optically tunable and high mechanical strength polymer nanocomposite films. RGO-doped poly(vinyl alcohol) (PVA) nanocomposite films were prepared via solution casting. Low level RGO doping significantly altered the structural, optical and mechanical properties of pure PVA films. Most of the band structure parameters like direct/indirect band gap, band tail, refractive index, dielectric constant, optical conductivity and dispersion parameters were investigated in detail for the first time. Tauc's, Wemple-DiDomenico, Helpin-Tsai and mixture rule models were employed to investigate optical and mechanical parameters. The applied models reinforced the experimental results in the present study. Advanced analytical techniques were engaged to characterize the nanocomposites films.

In Situ X-ray Absorption Near-Edge Structure Spectroscopy of ZnO Nanowire Growth During Chemical Bath Deposition

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

McPeak, Kevin M.; Becker, Matthew A.; Britton, Nathan G.

2010-12-03

Chemical bath deposition (CBD) offers a simple and inexpensive route to deposit semiconductor nanostructures, but lack of fundamental understanding and control of the underlying chemistry has limited its versatility. Here we report the first use of in situ X-ray absorption spectroscopy during CBD, enabling detailed investigation of both reaction mechanisms and kinetics of ZnO nanowire growth from zinc nitrate and hexamethylenetetramine (HMTA) precursors. Time-resolved X-ray absorption near-edge structure (XANES) spectra were used to quantify Zn(II) speciation in both solution and solid phases. ZnO crystallizes directly from [Zn(H{sub 2}O){sub 6}]{sup 2+} without long-lived intermediates. Using ZnO nanowire deposition as an example,more » this study establishes in situ XANES spectroscopy as an excellent quantitative tool to understand CBD of nanomaterials.« less

Synthesis of nanostructures in nanowires using sequential catalyst reactions

PubMed Central

Panciera, F.; Chou, Y.-C.; Reuter, M.C.; Zakharov, D.; Stach, E.A.; Hofmann, S.; Ross, F.M.

2016-01-01

Nanowire growth by the vapor-liquid-solid process enables a high level of control over nanowire composition, diameter, growth direction, branching and kinking, periodic twinning, and crystal structure. The tremendous impact of VLS-grown nanowires is due to this structural versatility, generating applications ranging from solid state lighting and single photon sources to thermoelectric devices. Here we show that the morphology of these nanostructures can be further tailored by using the liquid droplets that catalyze nanowire growth as a “mixing bowl”, in which growth materials are sequentially supplied to nucleate new phases. Growing within the liquid, these phases adopt the shape of faceted nanocrystals that are then incorporated into the nanowires by further growth. We demonstrate this concept by epitaxially incorporating metal silicide nanocrystals into Si nanowires with defect-free interfaces, and discuss how this process can be generalized to create complex nanowire-based heterostructures. PMID:26168344

High-wafer-yield, high-performance vertical cavity surface-emitting lasers

NASA Astrophysics Data System (ADS)

Li, Gabriel S.; Yuen, Wupen; Lim, Sui F.; Chang-Hasnain, Constance J.

1996-04-01

Vertical cavity surface emitting lasers (VCSELs) with very low threshold current and voltage of 340 (mu) A and 1.5 V is achieved. The molecular beam epitaxially grown wafers are grown with a highly accurate, low cost and versatile pre-growth calibration technique. One- hundred percent VCSEL wafer yield is obtained. Low threshold current is achieved with a native oxide confined structure with excellent current confinement. Single transverse mode with stable, predetermined polarization direction up to 18 times threshold is also achieved, due to stable index guiding provided by the structure. This is the highest value reported to data for VCSELs. We have established that p-contact annealing in these devices is crucial for low voltage operation, contrary to the general belief. Uniform doping in the mirrors also appears not to be inferior to complicated doping engineering. With these design rules, very low threshold voltage VCSELs are achieved with very simple growth and fabrication steps.

A Sensor Data Fusion System Based on k-Nearest Neighbor Pattern Classification for Structural Health Monitoring Applications

PubMed Central

Vitola, Jaime; Pozo, Francesc; Tibaduiza, Diego A.; Anaya, Maribel

2017-01-01

Civil and military structures are susceptible and vulnerable to damage due to the environmental and operational conditions. Therefore, the implementation of technology to provide robust solutions in damage identification (by using signals acquired directly from the structure) is a requirement to reduce operational and maintenance costs. In this sense, the use of sensors permanently attached to the structures has demonstrated a great versatility and benefit since the inspection system can be automated. This automation is carried out with signal processing tasks with the aim of a pattern recognition analysis. This work presents the detailed description of a structural health monitoring (SHM) system based on the use of a piezoelectric (PZT) active system. The SHM system includes: (i) the use of a piezoelectric sensor network to excite the structure and collect the measured dynamic response, in several actuation phases; (ii) data organization; (iii) advanced signal processing techniques to define the feature vectors; and finally; (iv) the nearest neighbor algorithm as a machine learning approach to classify different kinds of damage. A description of the experimental setup, the experimental validation and a discussion of the results from two different structures are included and analyzed. PMID:28230796

A Sensor Data Fusion System Based on k-Nearest Neighbor Pattern Classification for Structural Health Monitoring Applications.

PubMed

Vitola, Jaime; Pozo, Francesc; Tibaduiza, Diego A; Anaya, Maribel

2017-02-21

Civil and military structures are susceptible and vulnerable to damage due to the environmental and operational conditions. Therefore, the implementation of technology to provide robust solutions in damage identification (by using signals acquired directly from the structure) is a requirement to reduce operational and maintenance costs. In this sense, the use of sensors permanently attached to the structures has demonstrated a great versatility and benefit since the inspection system can be automated. This automation is carried out with signal processing tasks with the aim of a pattern recognition analysis. This work presents the detailed description of a structural health monitoring (SHM) system based on the use of a piezoelectric (PZT) active system. The SHM system includes: (i) the use of a piezoelectric sensor network to excite the structure and collect the measured dynamic response, in several actuation phases; (ii) data organization; (iii) advanced signal processing techniques to define the feature vectors; and finally; (iv) the nearest neighbor algorithm as a machine learning approach to classify different kinds of damage. A description of the experimental setup, the experimental validation and a discussion of the results from two different structures are included and analyzed.

Strategies for specifically directing metal functionalization of protein nanotubes: constructing protein coated silver nanowires

NASA Astrophysics Data System (ADS)

Carreño-Fuentes, Liliana; Ascencio, Jorge A.; Medina, Ariosto; Aguila, Sergio; Palomares, Laura A.; Ramírez, Octavio T.

2013-06-01

Biological molecules that self-assemble in the nanoscale range are useful multifunctional materials. Rotavirus VP6 protein self-assembles into tubular structures in the absence of other rotavirus proteins. Here, we present strategies for selectively directing metal functionalization to the lumen of VP6 nanotubes. The specific in situ metal reduction in the inner surface of nanotube walls was achieved by the simple modification of a method previously reported to functionalize the nanotube outer surface. Silver nanorods and nanowires as long as 1.5 μm were formed inside the nanotubes by coalescence of nanoparticles. Such one-dimensional structures were longer than others previously obtained using bioscaffolds. The interactions between silver ions and the nanotube were simulated to understand the conditions that allowed nanowire formation. Molecular docking showed that a naturally occurring arrangement of aspartate residues enabled the stabilization of silver ions on the internal surface of the VP6 nanotubes. This is the first time that such a spatial arrangement has been proposed for the nucleation of silver nanoparticles, opening the possibility of using such an array to direct functionalization of other biomolecules. These results demonstrate the natural capabilities of VP6 nanotubes to function as a versatile biotemplate for nanomaterials.

Enhancing the versatility of wireless biopotential acquisition for myoelectric prosthetic control

NASA Astrophysics Data System (ADS)

Bercich, Rebecca A.; Wang, Zhi; Mei, Henry; Hammer, Lauren H.; Seburn, Kevin L.; Hargrove, Levi J.; Irazoqui, Pedro P.

2016-08-01

Objective. A significant challenge in rehabilitating upper-limb amputees with sophisticated, electric-powered prostheses is sourcing reliable and independent channels of motor control information sufficient to precisely direct multiple degrees of freedom simultaneously. Approach. In response to the expressed needs of clinicians, we have developed a miniature, batteryless recording device that utilizes emerging integrated circuit technology and optimal impedance matching for magnetic resonantly coupled (MRC) wireless power transfer to improve the performance and versatility of wireless electrode interfaces with muscle. Main results. In this work we describe the fabrication and performance of a fully wireless and batteryless EMG recording system and use of this system to direct virtual and electric-powered limbs in real-time. The advantage of using MRC to optimize power transfer to a network of wireless devices is exhibited by EMG collected from an array of eight devices placed circumferentially around a human subject’s forearm. Significance. This is a comprehensive, low-cost, and non-proprietary solution that provides unprecedented versatility of configuration to direct myoelectric prostheses without wired connections to the body. The amenability of MRC to varied coil geometries and arrangements has the potential to improve the efficiency and robustness of wireless power transfer links at all levels of upper-limb amputation. Additionally, the wireless recording device’s programmable flash memory and selectable features will grant clinicians the unique ability to adapt and personalize the recording system’s functional protocol for patient- or algorithm-specific needs.

A versatile scalable PET processing system

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

H. Dong, A. Weisenberger, J. McKisson, Xi Wenze, C. Cuevas, J. Wilson, L. Zukerman

2011-06-01

Positron Emission Tomography (PET) historically has major clinical and preclinical applications in cancerous oncology, neurology, and cardiovascular diseases. Recently, in a new direction, an application specific PET system is being developed at Thomas Jefferson National Accelerator Facility (Jefferson Lab) in collaboration with Duke University, University of Maryland at Baltimore (UMAB), and West Virginia University (WVU) targeted for plant eco-physiology research. The new plant imaging PET system is versatile and scalable such that it could adapt to several plant imaging needs - imaging many important plant organs including leaves, roots, and stems. The mechanical arrangement of the detectors is designed tomore » accommodate the unpredictable and random distribution in space of the plant organs without requiring the plant be disturbed. Prototyping such a system requires a new data acquisition system (DAQ) and data processing system which are adaptable to the requirements of these unique and versatile detectors.« less

Directional sensitivity of the retina: A layered scattering model of outer-segment photoreceptor pigments

PubMed Central

Vohnsen, Brian

2014-01-01

Photoreceptor outer segments have been modeled as stacked arrays of discs or membrane infoldings containing visual pigments with light-induced dipole moments. Waveguiding has been excluded so fields diffract beyond the physical boundaries of each photoreceptor cell. Optical reciprocity is used to argue for identical radiative and light gathering properties of pigments to model vision. Two models have been introduced: one a macroscopic model that assumes a uniform pigment density across each layer and another microscopic model that includes the spatial location of each pigment molecule within each layer. Both models result in highly similar directionality at the pupil plane which proves to be insensitive to the exact details of the outer-segment packing being predominantly determined by the first and last contributing layers as set by the fraction of bleaching. The versatility of the microscopic model is demonstrated with an array of examples that includes the Stiles-Crawford effect, visibility of a focused beam of light and the role of defocus. PMID:24877016

The centrality of RNA for engineering gene expression

PubMed Central

Chappell, James; Takahashi, Melissa K; Meyer, Sarai; Loughrey, David; Watters, Kyle E; Lucks, Julius

2013-01-01

Synthetic biology holds promise as both a framework for rationally engineering biological systems and a way to revolutionize how we fundamentally understand them. Essential to realizing this promise is the development of strategies and tools to reliably and predictably control and characterize sophisticated patterns of gene expression. Here we review the role that RNA can play towards this goal and make a case for why this versatile, designable, and increasingly characterizable molecule is one of the most powerful substrates for engineering gene expression at our disposal. We discuss current natural and synthetic RNA regulators of gene expression acting at key points of control – transcription, mRNA degradation, and translation. We also consider RNA structural probing and computational RNA structure predication tools as a way to study RNA structure and ultimately function. Finally, we discuss how next-generation sequencing methods are being applied to the study of RNA and to the characterization of RNA's many properties throughout the cell. PMID:24124015

Looking at the Disordered Proteins through the Computational Microscope

PubMed Central

2018-01-01

Intrinsically disordered proteins (IDPs) have attracted wide interest over the past decade due to their surprising prevalence in the proteome and versatile roles in cell physiology and pathology. A large selection of IDPs has been identified as potential targets for therapeutic intervention. Characterizing the structure–function relationship of disordered proteins is therefore an essential but daunting task, as these proteins can adapt transient structure, necessitating a new paradigm for connecting structural disorder to function. Molecular simulation has emerged as a natural complement to experiments for atomic-level characterizations and mechanistic investigations of this intriguing class of proteins. The diverse range of length and time scales involved in IDP function requires performing simulations at multiple levels of resolution. In this Outlook, we focus on summarizing available simulation methods, along with a few interesting example applications. We also provide an outlook on how these simulation methods can be further improved in order to provide a more accurate description of IDP structure, binding, and assembly.

Complex DNA Brick Assembly.

PubMed

Ong, Luvena L; Ke, Yonggang

2017-01-01

DNA nanostructures are a useful technology for precisely organizing and manipulating nanomaterials. The DNA bricks method is a modular and versatile platform for applications requiring discrete or periodic structures with complex three-dimensional features. Here, we describe how structures are designed from the fundamental strand architecture through assembly and characterization of the formed structures.

Self-assembled hierarchically structured organic-inorganic composite systems.

PubMed

Tritschler, Ulrich; Cölfen, Helmut

2016-05-13

Designing bio-inspired, multifunctional organic-inorganic composite materials is one of the most popular current research objectives. Due to the high complexity of biocomposite structures found in nacre and bone, for example, a one-pot scalable and versatile synthesis approach addressing structural key features of biominerals and affording bio-inspired, multifunctional organic-inorganic composites with advanced physical properties is highly challenging. This article reviews recent progress in synthesizing organic-inorganic composite materials via various self-assembly techniques and in this context highlights a recently developed bio-inspired synthesis concept for the fabrication of hierarchically structured, organic-inorganic composite materials. This one-step self-organization concept based on simultaneous liquid crystal formation of anisotropic inorganic nanoparticles and a functional liquid crystalline polymer turned out to be simple, fast, scalable and versatile, leading to various (multi-)functional composite materials, which exhibit hierarchical structuring over several length scales. Consequently, this synthesis approach is relevant for further progress and scientific breakthrough in the research field of bio-inspired and biomimetic materials.

Multilayer networks reveal the spatial structure of seed-dispersal interactions across the Great Rift landscapes.

PubMed

Timóteo, Sérgio; Correia, Marta; Rodríguez-Echeverría, Susana; Freitas, Helena; Heleno, Ruben

2018-01-10

Species interaction networks are traditionally explored as discrete entities with well-defined spatial borders, an oversimplification likely impairing their applicability. Using a multilayer network approach, explicitly accounting for inter-habitat connectivity, we investigate the spatial structure of seed-dispersal networks across the Gorongosa National Park, Mozambique. We show that the overall seed-dispersal network is composed by spatially explicit communities of dispersers spanning across habitats, functionally linking the landscape mosaic. Inter-habitat connectivity determines spatial structure, which cannot be accurately described with standard monolayer approaches either splitting or merging habitats. Multilayer modularity cannot be predicted by null models randomizing either interactions within each habitat or those linking habitats; however, as habitat connectivity increases, random processes become more important for overall structure. The importance of dispersers for the overall network structure is captured by multilayer versatility but not by standard metrics. Highly versatile species disperse many plant species across multiple habitats, being critical to landscape functional cohesion.

Four chemical trends will shape the next decade's directions in Perfluoroalkyl and Polyfluoroalkyl substances research

NASA Astrophysics Data System (ADS)

Kotthoff, Matthias; Bücking, Mark

2018-04-01

Per- and polyfluoroalkyl substances (PFAS) represent a versatile group of ubiquitously occurring chemicals of increasing regulatory concern. The past years lead to an ever expanding portfolio of detected anthropogenic PFAS in numerous products encountered in daily life. Yet no clear picture of the full range of individual substance that comprise PFAS is available and this challenges analytical and engineering sciences. Authorities struggle to cope with uncertainties in managing risk of harm posed by PFAS.This is a result of an incomplete understanding of the range of compounds that they comprise in differing products. There are analytical uncertainties identifying PFAS and estimating the concentrations of the total PFAS loadindividual molecules remain unknown. There are four major trends from the chemical perspective that will shape PFAS research for the next decade. 1.Mobility: A wide and dynamic distribution of short chain PFAS due to their high polarity, persistency and volatility. 2.Substitution of regulated substances: The ban or restrictions of individual molecules will lead to a replacement with substitutes of similar concern. 3.Increase in structural diversity of existing PFAS molecules: Introduction of e.g. hydrogens and chlorine atoms instead of fluorine, as well as branching and cross-linking lead to a high versatility of unknown target molecules. 4. Unknown “Dark Matter”: The amount, identity, formation pathways, and transformation dynamics of polymers and PFAS precursors are largely unknown. These directions require optimized analytical setups, especially multi-methods, and semi-specific tools to determine PFAS-sum parameters in any relevant matrix.

Insights into the unique functionality of inorganic micro/nanoparticles for versatile ultrasound theranostics.

PubMed

Qian, Xiaoqin; Han, Xiaoxia; Chen, Yu

2017-10-01

The clinical ultrasound (US)-based theranostic biomedicine suffers from the critical issue that traditional microbubbles (MBs) have lots of drawbacks such as low stability, large particle size, difficult structural control, etc. The unique composition, structure and functionality of inorganic micro/nanoplatforms have shown their great prospect for solving these critical issues and drawbacks of traditional organic MBs. This review summarizes and discusses the state-of-art development on exploring inorganic micro/nanoparticles for versatile US-based biomedical applications, ranging from US imaging, photoacoustic imaging, sonodynamic therapy, high intensity-focused US ablation and US-triggered chemotherapy. These inorganic micro/nanoplatforms include silica-based particles, Au, carbon nanotubes, TiO 2 , manganese oxide, iron oxide, Prussian blue, inorganic gas-generating nanoparticles and their versatile composite micro/nanosystems. Especially, their unique structure/composition-functionality relationships and biocompatibility/biosafety in US-based theranostics have been discussed and revealed in detail. Their facing challenges and future developments are finally discussed to promote their further clinical translations. It is highly expected that these inorganic micro/nanoplatforms will enter the clinical stage to benefit the personalized theranostics biomedicine based on their unique functionalities and high performance as necessarily required in US-based theranostics. Copyright © 2017 Elsevier Ltd. All rights reserved.

New Method for Producing Significant Amounts of RNA Labeled at Specific Sites | Center for Cancer Research

Cancer.gov

Among biomacromolecules, RNA is the most versatile, and it plays indispensable roles in almost all aspects of biology. For example, in addition to serving as mRNAs coding for proteins, RNAs regulate gene expression, such as controlling where, when, and how efficiently a gene gets expressed, participate in RNA processing, encode the genetic information of some viruses, serve as scaffolds, and even possess enzymatic activity. To study these RNAs and their biological functions and to make use of those RNA activities for biomedical applications, researchers first need to make various types of RNA. For structural biologists incorporating modified or labeled nucleotides at specific sites in RNA molecules of interest is critical to gain structural insight into RNA functions. However, placing labeled or modified residue(s) in desired positions in a large RNA has not been possible until now.

The poly(C)-binding proteins: a multiplicity of functions and a search for mechanisms.

PubMed Central

Makeyev, Aleksandr V; Liebhaber, Stephen A

2002-01-01

The poly(C) binding proteins (PCBPs) are encoded at five dispersed loci in the mouse and human genomes. These proteins, which can be divided into two groups, hnRNPs K/J and the alphaCPs (alphaCP1-4), are linked by a common evolutionary history, a shared triple KH domain configuration, and by their poly(C) binding specificity. Given these conserved characteristics it is remarkable to find a substantial diversity in PCBP functions. The roles of these proteins in mRNA stabilization, translational activation, and translational silencing suggest a complex and diverse set of post-transcriptional control pathways. Their additional putative functions in transcriptional control and as structural components of important DNA-protein complexes further support their remarkable structural and functional versatility. Clearly the identification of additional binding targets and delineation of corresponding control mechanisms and effector pathways will establish highly informative models for further exploration. PMID:12003487

The poly(C)-binding proteins: a multiplicity of functions and a search for mechanisms.

PubMed

Makeyev, Aleksandr V; Liebhaber, Stephen A

2002-03-01

The poly(C) binding proteins (PCBPs) are encoded at five dispersed loci in the mouse and human genomes. These proteins, which can be divided into two groups, hnRNPs K/J and the alphaCPs (alphaCP1-4), are linked by a common evolutionary history, a shared triple KH domain configuration, and by their poly(C) binding specificity. Given these conserved characteristics it is remarkable to find a substantial diversity in PCBP functions. The roles of these proteins in mRNA stabilization, translational activation, and translational silencing suggest a complex and diverse set of post-transcriptional control pathways. Their additional putative functions in transcriptional control and as structural components of important DNA-protein complexes further support their remarkable structural and functional versatility. Clearly the identification of additional binding targets and delineation of corresponding control mechanisms and effector pathways will establish highly informative models for further exploration.

Versatile monolithic 2-micron laser systems

NASA Astrophysics Data System (ADS)

Wysmolek, M.; Steinke, M.; Neumann, J.; Kracht, D.

2018-02-01

To answer a growing demand in development of high power pulsed and continuous wave sources at 2 micron spectral range we have participated in several projects, which resulted in a delivery of versatile monolithic sources providing picosecond, nanosecond and CW laser signal. As an example of pulsed sources we developed all-fiber monolithic devices based on a directly modulated laser diode and gain-switched laser diode to generate nanosecond and picosecond pulses, respectively, which are amplified in the same fiber amplifier chain up to 50 µJ with 96 ps and more than 1 mJ with pulses longer than 35 ns.

Structural insight into RNA recognition motifs: versatile molecular Lego building blocks for biological systems.

PubMed

Muto, Yutaka; Yokoyama, Shigeyuki

2012-01-01

'RNA recognition motifs (RRMs)' are common domain-folds composed of 80-90 amino-acid residues in eukaryotes, and have been identified in many cellular proteins. At first they were known as RNA binding domains. Through discoveries over the past 20 years, however, the RRMs have been shown to exhibit versatile molecular recognition activities and to behave as molecular Lego building blocks to construct biological systems. Novel RNA/protein recognition modes by RRMs are being identified, and more information about the molecular recognition by RRMs is becoming available. These RNA/protein recognition modes are strongly correlated with their biological significance. In this review, we would like to survey the recent progress on these versatile molecular recognition modules. Copyright © 2012 John Wiley & Sons, Ltd.

Caveolae structure and function

PubMed Central

Thomas, Candice M; Smart, Eric J

2008-01-01

Abstract Studies on the structure and function of caveolae have revealed how this versatile subcellular organelle can influence numerous signalling pathways. This brief review will discuss a few of the key features of caveolae as it relates to signalling and disease processes. PMID:18315571

Dust remobilization in fusion plasmas under steady state conditions

NASA Astrophysics Data System (ADS)

Tolias, P.; Ratynskaia, S.; De Angeli, M.; De Temmerman, G.; Ripamonti, D.; Riva, G.; Bykov, I.; Shalpegin, A.; Vignitchouk, L.; Brochard, F.; Bystrov, K.; Bardin, S.; Litnovsky, A.

2016-02-01

The first combined experimental and theoretical studies of dust remobilization by plasma forces are reported. The main theoretical aspects of remobilization in fusion devices under steady state conditions are analyzed. In particular, the dominant role of adhesive forces is highlighted and generic remobilization conditions—direct lift-up, sliding, rolling—are formulated. A novel experimental technique is proposed, based on controlled adhesion of dust grains on tungsten samples combined with detailed mapping of the dust deposition profile prior and post plasma exposure. Proof-of-principle experiments in the TEXTOR tokamak and the EXTRAP-T2R reversed-field pinch are presented. The versatile environment of the linear device Pilot-PSI allowed for experiments with different magnetic field topologies and varying plasma conditions that were complemented with camera observations.

Electrodeposition for Electrochemical Energy Conversion and Storage Devices

NASA Astrophysics Data System (ADS)

Shaigan, Nima

Electrodeposition of metals, alloys, metal oxides, conductive polymers, and their composites plays a pivotal role in fabrication processes of some recently developed electrochemical energy devices, most particularly fuel cells, supercapacitors, and batteries. Unique nanoscale architectures of electrocatalysts for low temperature fuel cells, including proton exchange membrane fuel cell (PEMFC) and direct methanol fuel cell (DMFC), can only be obtained through electrodeposition processes. Promising, cost-effective conductive/protective coatings for stainless steel interconnects used in solid oxide fuel cells (SOFCs) have been achieved employing a variety of electrodeposition techniques. In supercapacitors, anodic deposition of metal oxides, conductive polymers, and their composites is a versatile technique for fabrication of electrodes with distinctive morphology and exceptional specific capacitance. Electrodeposition is also very recently employed for preparation of Sn-based anodes for lithium ion batteries.

Laser-induced Forward Transfer of Ag Nanopaste.

PubMed

Breckenfeld, Eric; Kim, Heungsoo; Auyeung, Raymond C Y; Piqué, Alberto

2016-03-31

Over the past decade, there has been much development of non-lithographic methods(1-3) for printing metallic inks or other functional materials. Many of these processes such as inkjet(3) and laser-induced forward transfer (LIFT)(4) have become increasingly popular as interest in printable electronics and maskless patterning has grown. These additive manufacturing processes are inexpensive, environmentally friendly, and well suited for rapid prototyping, when compared to more traditional semiconductor processing techniques. While most direct-write processes are confined to two-dimensional structures and cannot handle materials with high viscosity (particularly inkjet), LIFT can transcend both constraints if performed properly. Congruent transfer of three dimensional pixels (called voxels), also referred to as laser decal transfer (LDT)(5-9), has recently been demonstrated with the LIFT technique using highly viscous Ag nanopastes to fabricate freestanding interconnects, complex voxel shapes, and high-aspect-ratio structures. In this paper, we demonstrate a simple yet versatile process for fabricating a variety of micro- and macroscale Ag structures. Structures include simple shapes for patterning electrical contacts, bridging and cantilever structures, high-aspect-ratio structures, and single-shot, large area transfers using a commercial digital micromirror device (DMD) chip.

Laser-induced Forward Transfer of Ag Nanopaste

PubMed Central

Breckenfeld, Eric; Kim, Heungsoo; Auyeung, Raymond C. Y.; Piqué, Alberto

2016-01-01

Over the past decade, there has been much development of non-lithographic methods1-3 for printing metallic inks or other functional materials. Many of these processes such as inkjet3 and laser-induced forward transfer (LIFT)4 have become increasingly popular as interest in printable electronics and maskless patterning has grown. These additive manufacturing processes are inexpensive, environmentally friendly, and well suited for rapid prototyping, when compared to more traditional semiconductor processing techniques. While most direct-write processes are confined to two-dimensional structures and cannot handle materials with high viscosity (particularly inkjet), LIFT can transcend both constraints if performed properly. Congruent transfer of three dimensional pixels (called voxels), also referred to as laser decal transfer (LDT)5-9, has recently been demonstrated with the LIFT technique using highly viscous Ag nanopastes to fabricate freestanding interconnects, complex voxel shapes, and high-aspect-ratio structures. In this paper, we demonstrate a simple yet versatile process for fabricating a variety of micro- and macroscale Ag structures. Structures include simple shapes for patterning electrical contacts, bridging and cantilever structures, high-aspect-ratio structures, and single-shot, large area transfers using a commercial digital micromirror device (DMD) chip. PMID:27077645

Versatile peroxidase of Bjerkandera fumosa: substrate and inhibitor specificity.

PubMed

Pozdnyakova, Natalia; Makarov, Oleg; Chernyshova, Marina; Turkovskaya, Olga; Jarosz-Wilkolazka, Anna

2013-01-10

The inhibitor and substrate specificities of versatile peroxidase from Bjerkandera fumosa (VPBF) were studied. Two different effects were found: NaN(3), Tween-80, anthracene, and fluorene decreased the activity of VPBF, but p-aminobenzoic acid increased it. A mixed mechanism of effector influence on the activity of this enzyme was shown. The catalytic properties of VPBF in the oxidation of mono- and polycyclic aromatic compounds were studied also. 2,7-Diaminofluorene, ABTS, veratryl alcohol, and syringaldazine can be oxidized by VPBF in two ways: either directly by the enzyme or by diffusible chelated Mn(3+) as an oxidizing agent. During VPBF oxidation of 2,7-diaminofluorene, both with and without Mn(2+), biphasic kinetics with apparent saturation in both micromolar and millimolar ranges were obtained. In the case of ABTS, inhibition of VPBF activity by an excess of substrate was observed. Direct oxidation of p-aminobenzoic acid by versatile peroxidase was found for the first time. The oxidation of three- and four-ring PAHs by VPBF was investigated, and the oxidation of anthracene, phenanthrene, fluorene, pyrene, chrysene, and fluoranthene was shown. The products of PAH oxidation (9,10-anthraquinone, 9,10-phenanthrenequinone, and 9-fluorenone) catalyzed by VPBF were identified. Copyright © 2012 Elsevier Inc. All rights reserved.

Structural and Process Factors That Influence Clinical Nurse Specialist Role Implementation.

PubMed

Kilpatrick, Kelley; Tchouaket, Eric; Carter, Nancy; Bryant-Lukosius, Denise; DiCenso, Alba

2016-01-01

The aim of this study was to examine the influence of structure and process on clinical nurse specialist (CNS) role implementation. We conducted a secondary analysis of cross-sectional survey data. The study was performed in Canada. The authors included 445 of 471 questionnaires (94.5%) of graduate-prepared CNSs. Based on Donabedian's framework, we conducted a secondary analysis of CNS responses using hierarchical regression. The internal consistency of the 6 CNS role dimensions and team dynamics subscales was excellent. The use of a framework to guide CNS role implementation influences all the role dimensions. Employer understanding of the CNS role, working in an urban catchment area, specialty certification, and more years in a CNS role had a direct positive influence on team dynamics. Full-time employment exerted a direct negative influence on this dimension. Furthermore, team dynamics (as a mediator variable), seeing patients in practice, and having an office in the clinical unit exerted a direct positive influence on the clinical dimension. Having an annual performance appraisal and a job description exerted a direct negative influence on the clinical dimension. Employer understanding, working in an urban area, full-time employment, and specialty certification had an indirect effect on the clinical dimension. Accountability to a nonnurse manager exerted a direct negative influence on the education dimension. The research and scholarly/professional development dimensions were influenced by more years in a CNS role. Accountability to a nurse manager exerted a direct positive influence on the organizational leadership dimension; unionization and seeing patients in practice had a direct negative influence on this dimension. Seeing patients in practice and full-time employment exerted a direct positive influence on the consultation dimension. The identification of structures and processes that influence CNS role implementation may inform strategies used by providers and decision makers to optimize these roles across healthcare settings and support the delivery of high-quality care.

A versatile strategy toward binary three-dimensional architectures based on engineering graphene aerogels with porous carbon fabrics for supercapacitors.

PubMed

Song, Wei-Li; Song, Kuo; Fan, Li-Zhen

2015-02-25

Graphene-based supercapacitors and related flexible devices have attracted great attention because of the increasing demands in the energy storage. As promising three-dimensional (3D) nanostructures in the supercapacitor electrodes, graphene-based aerogels have been paid dramatic attention recently, and numerous methods have been developed for enhancing their performance in energy storage. In this study, an exclusive strategy is presented toward directly in situ growing reduced graphene oxide (RGO) aerogels inside the 3D porous carbon fabrics for engineering the interfaces of the resulting binary 3D architectures. Such unique architectures have shown various advantages in the improvements of the nanostructures and chemical compositions, allowing them to possess much enhanced electrochemical properties (391, 229, and 195 F g(-1) at current densities of 0.1, 1, and 5 A g(-1), respectively) with excellent cycling stability in comparison with the neat RGO aerogels. The results of the performance in the flexible all-solid-state supercapacitors along with discussion on the related mechanisms in the electrochemical properties indicate the remaining issues and associated opportunities in the development of advanced energy storage devices. This strategy is relatively facile, versatile, and tunable, which highlights a unique platform for engineering various 3D porous structures in many fields.

Chemical copatterning strategies using azlactone-based block copolymers

DOE PAGES

Masigol, Mohammadali; Barua, Niloy; Retterer, Scott T.; ...

2017-09-01

Interfaces can be modified with azlactone-functional polymers in order to manipulate the chemical surface reactivity. Azlactone groups are highly reactive toward amine, thiol, and alcohol nucleophiles, providing a versatile coupling chemistry for secondary surface modification. Azlactone-based surface polymers have been explored in numerous applications, including chemical and biological capture, sensing, and cell culture. These applications often require that the polymer is copatterned within a chemically or biologically inert background; however, common fabrication methods degrade azlactone groups during processing steps or result in polymer films with poorly controlled thicknesses. Here, the authors develop fabrication strategies using parylene lift-off and interface-directed assemblymore » methods to generate microscale patterns of azlactone-based block copolymer in chemically or biologically inert backgrounds. The functionality of azlactone groups was preserved during fabrication, and patterned films appeared as uniform, 80–120nm brushlike films. The authors also develop a patterning approach that uses a novel microcontact stamping method to generate cross-linked, three-dimensional structures of azlactone-based polymers with controllable, microscale thicknesses. The authors identify the benefits of each approach and expect these polymers and patterning strategies to provide a versatile toolbox for developing synthetic interfaces with tuned chemical and physical features for sensing, cell culture, or material capture applications.« less

Chemical copatterning strategies using azlactone-based block copolymers

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

Masigol, Mohammadali; Barua, Niloy; Retterer, Scott T.

Interfaces can be modified with azlactone-functional polymers in order to manipulate the chemical surface reactivity. Azlactone groups are highly reactive toward amine, thiol, and alcohol nucleophiles, providing a versatile coupling chemistry for secondary surface modification. Azlactone-based surface polymers have been explored in numerous applications, including chemical and biological capture, sensing, and cell culture. These applications often require that the polymer is copatterned within a chemically or biologically inert background; however, common fabrication methods degrade azlactone groups during processing steps or result in polymer films with poorly controlled thicknesses. Here, the authors develop fabrication strategies using parylene lift-off and interface-directed assemblymore » methods to generate microscale patterns of azlactone-based block copolymer in chemically or biologically inert backgrounds. The functionality of azlactone groups was preserved during fabrication, and patterned films appeared as uniform, 80–120nm brushlike films. The authors also develop a patterning approach that uses a novel microcontact stamping method to generate cross-linked, three-dimensional structures of azlactone-based polymers with controllable, microscale thicknesses. The authors identify the benefits of each approach and expect these polymers and patterning strategies to provide a versatile toolbox for developing synthetic interfaces with tuned chemical and physical features for sensing, cell culture, or material capture applications.« less

Interactive Spacecraft Trajectory Design Strategies Featuring Poincare Map Topology

NASA Astrophysics Data System (ADS)

Schlei, Wayne R.

Space exploration efforts are shifting towards inexpensive and more agile vehicles. Versatility regarding spacecraft trajectories refers to the agility to correct deviations from an intended path or even the ability to adapt the future path to a new destination--all with limited spaceflight resources (i.e., small DeltaV budgets). Trajectory design methods for such nimble vehicles incorporate equally versatile procedures that allow for rapid and interactive decision making while attempting to reduce Delta V budgets, leading to a versatile trajectory design platform. A versatile design paradigm requires the exploitation of Poincare map topology , or the interconnected web of dynamical structures, existing within the chaotic dynamics of multi-body gravitational models to outline low-Delta V transfer options residing nearby to a current path. This investigation details an autonomous procedure to extract the periodic orbits (topology nodes) and correlated asymptotic flow structures (or the invariant manifolds representing topology links). The autonomous process summarized in this investigation (termed PMATE) overcomes discontinuities on the Poincare section that arise in the applied multi-body model (the planar circular restricted three-body problem) and detects a wide variety of novel periodic orbits. New interactive capabilities deliver a visual analytics foundation for versatile spaceflight design, especially for initial guess generation and manipulation. Such interactive strategies include the selection of states and arcs from Poincare section visualizations and the capabilities to draw and drag trajectories to remove dependency on initial state input. Furthermore, immersive selection is expanded to cull invariant manifold structures, yielding low-DeltaV or even DeltaV-free transfers between periodic orbits. The application of interactive design strategies featuring a dense extraction of Poincare map topology is demonstrated for agile spaceflight with a simple spacecraft rerouting scenario incorporating a very limited Delta V budget. In the Earth-Moon system, a low-DeltaV transfer from low Earth orbit (LEO) to the distant retrograde orbit (DRO) vicinity is derived with interactive topology-based design tactics. Finally, Poincare map topology is exploited in the Saturn-Enceladus system to explore a possible ballistic capture scenario around Enceladus.

Evaporative Optical Marangoni Assembly: Tailoring the Three-Dimensional Morphology of Individual Deposits of Nanoparticles from Sessile Drops.

PubMed

Anyfantakis, Manos; Varanakkottu, Subramanyan Namboodiri; Rudiuk, Sergii; Morel, Mathieu; Baigl, Damien

2017-10-25

We have recently devised the evaporative optical Marangoni assembly (eOMA), a novel and versatile interfacial flow-based method for directing the deposition of colloidal nanoparticles (NPs) on solid substrates from evaporating sessile drops along desired patterns using shaped UV light. Here, we focus on a fixed UV spot irradiation resulting in a cylinder-like deposit of assembled particles and show how the geometrical features of the single deposit can be tailored in three dimensions by simply adjusting the optical conditions or the sample composition, in a quantitative and reproducible manner. Sessile drops containing cationic NPs and a photosensitive surfactant at various concentrations are allowed to evaporate under a single UV beam with a diameter much smaller than that of the drop. After complete evaporation, the geometrical characteristics of the NP deposits are precisely assessed using optical profilometry. We show that both the volume and the radial size of the light-directed NP deposit can be adjusted by varying the diameter or the intensity of the UV beam or alternatively by changing the concentration of the photosensitive surfactant. Notably, in all these cases, the deposits display an almost constant median height corresponding to a few layers of particles. Moreover, both the radial and the axial extent of the patterns are tuned by changing the NP concentration. These results are explained by the correlation among the strength of Marangoni flow, the particle trapping efficiency, and the volume of the deposit, and by the role of evaporation-driven flow in strongly controlling the deposit height. Finally, we extend the versatility of eOMA by demonstrating that NPs down to 30 nm in diameter can be effectively patterned on glass or polymeric substrates.

Patterned Liquid Metal Contacts for Printed Carbon Nanotube Transistors.

PubMed

Andrews, Joseph B; Mondal, Kunal; Neumann, Taylor V; Cardenas, Jorge A; Wang, Justin; Parekh, Dishit P; Lin, Yiliang; Ballentine, Peter; Dickey, Michael D; Franklin, Aaron D

2018-05-14

Flexible and stretchable electronics are poised to enable many applications that cannot be realized with traditional, rigid devices. One of the most promising options for low-cost stretchable transistors are printed carbon nanotubes (CNTs). However, a major limiting factor in stretchable CNT devices is the lack of a stable and versatile contact material that forms both the interconnects and contact electrodes. In this work, we introduce the use of eutectic gallium-indium (EGaIn) liquid metal for electrical contacts to printed CNT channels. We analyze thin-film transistors (TFTs) fabricated using two different liquid metal deposition techniques-vacuum-filling polydimethylsiloxane (PDMS) microchannel structures and direct-writing liquid metals on the CNTs. The highest performing CNT-TFT was realized using vacuum-filled microchannel deposition with an in situ annealing temperature of 150 °C. This device exhibited an on/off ratio of more than 10 4 and on-currents as high as 150 μA/mm-metrics that are on par with other printed CNT-TFTs. Additionally, we observed that at room temperature the contact resistances of the vacuum-filled microchannel structures were 50% lower than those of the direct-write structures, likely due to the poor adhesion between the materials observed during the direct-writing process. The insights gained in this study show that stretchable electronics can be realized using low-cost and solely solution processing techniques. Furthermore, we demonstrate methods that can be used to electrically characterize semiconducting materials as transistors without requiring elevated temperatures or cleanroom processes.

Key experimental information on intermediate-range atomic structures in amorphous Ge2Sb2Te5 phase change material

NASA Astrophysics Data System (ADS)

Hosokawa, Shinya; Pilgrim, Wolf-Christian; Höhle, Astrid; Szubrin, Daniel; Boudet, Nathalie; Bérar, Jean-François; Maruyama, Kenji

2012-04-01

Laser-induced crystalline-amorphous phase change of Ge-Sb-Te alloys is the key mechanism enabling the fast and stable writing/erasing processes in rewritable optical storage devices, such as digital versatile disk (DVD) or blu-ray disk. Although the structural information in the amorphous phase is essential for clarifying this fast process, as well as long lasting stabilities of both the phases, experimental works were mostly limited to the short-range order by x ray absorption fine structure. Here we show both the short and intermediate-range atomic structures of amorphous DVD material, Ge2Sb2Te5 (GST), investigated by a combination of anomalous x ray scattering and reverse Monte Carlo modeling. From the obtained atomic configurations of amorphous GST, we have found that the Sb atoms and half of the Ge atoms play roles in the fast phase change process of order-disorder transition, while the remaining Ge atoms act for the proper activation energy of barriers between the amorphous and crystalline phases.

The crystal structure of the Hsp90 co-chaperone Cpr7 from Saccharomyces cerevisiae.

PubMed

Qiu, Yu; Ge, Qiangqiang; Wang, Mingxing; Lv, Hui; Ebrahimi, Mohammad; Niu, Liwen; Teng, Maikun; Li, Xu

2017-03-01

The versatility of Hsp90 can be attributed to the variety of co-chaperone proteins that modulate the role of Hsp90 in many cellular processes. As a co-chaperone of Hsp90, Cpr7 is essential for accelerating the cell growth in an Hsp90-containing trimeric complex. Here, we report the crystal structure of Cpr7 at a resolution of 1.8Å. It consists of an N-terminal PPI domain and a C-terminal TPR domain, and exhibits a U-shape conformation. Our studies revealed the aggregation state of Cpr7 in solution and the interaction properties between Cpr7 and the MEEVD sequence from the C-terminus of Hsp90. In addition, the structure and sequence analysis between Cpr7 and homologues revealed the structure basis both for the function differences between Cpr6 and Cpr7 and the functional complements between Cns1 and Cpr7. Our studies facilitate the understanding of Cpr7 and provide decent insights into the molecular mechanisms of the Hsp90 co-chaperone pathway. Copyright © 2017 Elsevier Inc. All rights reserved.

Platelets: versatile effector cells in hemostasis, inflammation, and the immune continuum

PubMed Central

Vieira-de-Abreu, Adriana; Campbell, Robert A.; Weyrich, Andrew S.

2015-01-01

Platelets are chief effector cells in hemostasis. In addition, however, their specializations include activities and intercellular interactions that make them key effectors in inflammation and in the continuum of innate and adaptive immunity. This review focuses on the immune features of human platelets and platelets from experimental animals and on interactions between inflammatory, immune, and hemostatic activities of these anucleate but complex and versatile cells. The experimental findings and evidence for physiologic immune functions include previously unrecognized biologic characteristics of platelets and are paralleled by new evidence for unique roles of platelets in inflammatory, immune, and thrombotic diseases. PMID:21818701

Controlled molecular self-assembly of complex three-dimensional structures in soft materials

PubMed Central

Huang, Changjin; Quinn, David; Suresh, Subra

2018-01-01

Many applications in tissue engineering, flexible electronics, and soft robotics call for approaches that are capable of producing complex 3D architectures in soft materials. Here we present a method using molecular self-assembly to generate hydrogel-based 3D architectures that resembles the appealing features of the bottom-up process in morphogenesis of living tissues. Our strategy effectively utilizes the three essential components dictating living tissue morphogenesis to produce complex 3D architectures: modulation of local chemistry, material transport, and mechanics, which can be engineered by controlling the local distribution of polymerization inhibitor (i.e., oxygen), diffusion of monomers/cross-linkers through the porous structures of cross-linked polymer network, and mechanical constraints, respectively. We show that oxygen plays a role in hydrogel polymerization which is mechanistically similar to the role of growth factors in tissue growth, and the continued growth of hydrogel enabled by diffusion of monomers/cross-linkers into the porous hydrogel similar to the mechanisms of tissue growth enabled by material transport. The capability and versatility of our strategy are demonstrated through biomimetics of tissue morphogenesis for both plants and animals, and its application to generate other complex 3D architectures. Our technique opens avenues to studying many growth phenomena found in nature and generating complex 3D structures to benefit diverse applications. PMID:29255037

Modelling of nanoscale quantum tunnelling structures using algebraic topology method

NASA Astrophysics Data System (ADS)

Sankaran, Krishnaswamy; Sairam, B.

2018-05-01

We have modelled nanoscale quantum tunnelling structures using Algebraic Topology Method (ATM). The accuracy of ATM is compared to the analytical solution derived based on the wave nature of tunnelling electrons. ATM provides a versatile, fast, and simple model to simulate complex structures. We are currently expanding the method for modelling electrodynamic systems.

Structural Order-Disorder Transformations Monitored by X-Ray Diffraction and Photoluminescence

ERIC Educational Resources Information Center

Lima, R. C.; Paris, E. C.; Leite, E. R.; Espinosa, J. W. M.; Souza, A. G.; Longo, E.

2007-01-01

A study was conducted to examine the structural order-disorder transformation promoted by controlled heat treatment using X-ray diffraction technique (XRD) and photoluminescence (PL) techniques as tools to monitor the degree of structural order. The experiment was observed to be versatile and easily achieved with low cost which allowed producing…

Prevalence and associated risk characteristics of HIV infection based on anal sexual role among men who have sex with men: a multi-city cross-sectional study in Western China.

PubMed

Zeng, Xin; Zhong, Xiaoni; Peng, Bin; Zhang, Yan; Kong, Cuie; Liu, Xiyao; Huang, Ailong

2016-08-01

The HIV prevalence among men who have sex with men (MSM) in Western China is substantial and increasing at an alarming rate. The current HIV infection prevalence among MSM in Western China and its associated risk characteristics were explored by looking at different anal sexual roles separately. A total 1245 MSM recruited by convenience sampling from multiple sources and areas in the Chongqing and Sichuan region were interviewed using an anonymous self-administered questionnaire with the assistance of investigators and then underwent HIV testing. Multivariate logistic regression was used to identify factors independently associated with HIV infection. Of the 1235 respondents who reported their sexual roles during anal sex with men, the overall HIV antibody positive rate was 21.21% (262/1235). With regard to the different anal sex roles, HIV-positive rates were significantly higher among men who played the '0.5' role (versatile, equal) and '0' role (only bottom or versatile, but mostly bottom) during anal sex with men than among those who played the '1' role (only top or versatile, but mostly top) (26.41% for '0.5' role, 26.20% for '0' role, and 15.19% for '1' role; Chi-square=22.66, p<0.0001). Statistically significant differences were not found between the '0.5' role and '0' role groups (p > 0.05). The '1' role MSM who had an education level lower than senior high school, a rural household registration, and low self-perceived severity status of AIDS, the '0.5' role MSM who had an education level lower than senior high school and had not undergone HIV testing in the recent 1 year, and the '0' role MSM who were retired or unemployed and had been diagnosed with a sexually transmitted disease by a doctor in the recent 6 months were more likely to be HIV-infected. In this study, the HIV prevalence among MSM was alarmingly high. Moreover, the '0.5' and '0' role MSM were found to have a higher risk of infection compared to the '1' role MSM, while respective risk characteristics were not completely the same across the three groups. Along with routine preventive intervention services, more focused and specific interventions are needed to target anal sex role classes separately. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Strand-specific Recognition of DNA Damages by XPD Provides Insights into Nucleotide Excision Repair Substrate Versatility*

PubMed Central

Buechner, Claudia N.; Heil, Korbinian; Michels, Gudrun; Carell, Thomas; Kisker, Caroline; Tessmer, Ingrid

2014-01-01

Recognition and removal of DNA damages is essential for cellular and organismal viability. Nucleotide excision repair (NER) is the sole mechanism in humans for the repair of carcinogenic UV irradiation-induced photoproducts in the DNA, such as cyclobutane pyrimidine dimers. The broad substrate versatility of NER further includes, among others, various bulky DNA adducts. It has been proposed that the 5′-3′ helicase XPD (xeroderma pigmentosum group D) protein plays a decisive role in damage verification. However, despite recent advances such as the identification of a DNA-binding channel and central pore in the protein, through which the DNA is threaded, as well as a dedicated lesion recognition pocket near the pore, the exact process of target site recognition and verification in eukaryotic NER still remained elusive. Our single molecule analysis by atomic force microscopy reveals for the first time that XPD utilizes different recognition strategies to verify structurally diverse lesions. Bulky fluorescein damage is preferentially detected on the translocated strand, whereas the opposite strand preference is observed for a cyclobutane pyrimidine dimer lesion. Both states, however, lead to similar conformational changes in the resulting specific complexes, indicating a merge to a “final” verification state, which may then trigger the recruitment of further NER proteins. PMID:24338567

Iron oxide nanomatrix facilitating metal ionization in matrix-assisted laser desorption/ionization mass spectrometry.

PubMed

Obena, Rofeamor P; Lin, Po-Chiao; Lu, Ying-Wei; Li, I-Che; del Mundo, Florian; Arco, Susan dR; Nuesca, Guillermo M; Lin, Chung-Chen; Chen, Yu-Ju

2011-12-15

The significance and epidemiological effects of metals to life necessitate the development of direct, efficient, and rapid method of analysis. Taking advantage of its simple, fast, and high-throughput features, we present a novel approach to metal ion detection by matrix-functionalized magnetic nanoparticle (matrix@MNP)-assisted MALDI-MS. Utilizing 21 biologically and environmentally relevant metal ion solutions, the performance of core and matrix@MNP against conventional matrixes in MALDI-MS and laser desorption ionization (LDI) MS were systemically tested to evaluate the versatility of matrix@MNP as ionization element. The matrix@MNPs provided 20- to >100-fold enhancement on detection sensitivity of metal ions and unambiguous identification through characteristic isotope patterns and accurate mass (<5 ppm), which may be attributed to its multifunctional role as metal chelator, preconcentrator, absorber, and reservoir of energy. Together with the comparison on the ionization behaviors of various metals having different ionization potentials (IP), we formulated a metal ionization mechanism model, alluding to the role of exciton pooling in matrix@MNP-assisted MALDI-MS. Moreover, the detection of Cu in spiked tap water demonstrated the practicability of this new approach as an efficient and direct alternative tool for fast, sensitive, and accurate determination of trace metal ions in real samples.

Hydration of AMP and ATP molecules in aqueous solution and solid films.

PubMed

Faizullin, Dzhigangir; Zakharchenko, Nataliya; Zuev, Yuriy; Puzenko, Alexander; Levy, Evgeniya; Feldman, Yuri

2013-11-20

Water enables life and plays a critical role in biology. Considered as a versatile and adaptive component of the cell, water engages a wide range of biomolecular interactions. An organism can exist and function only if its self-assembled molecular structures are hydrated. It was shown recently that switching of AMP/ATP binding to the insulin-independent glucose transporter Human Erythrocyte Glucose Transport Protein (GLUT1) may greatly influence the ratio of bulk and bound water during regulation of glucose uptake by red blood cells. In this paper, we present the results on the hydration properties of AMP/ATP obtained by means of dielectric spectroscopy in aqueous solution and for fully ionized forms in solid amorphous films with the help of gravimetric studies.

Ultrafast and versatile spectroscopy by temporal Fourier transform

NASA Astrophysics Data System (ADS)

Zhang, Chi; Wei, Xiaoming; Marhic, Michel E.; Wong, Kenneth K. Y.

2014-06-01

One of the most remarkable and useful properties of a spatially converging lens system is its inherent ability to perform the Fourier transform; the same applies for the time-lens system. At the back focal plane of the time-lens, the spectral information can be instantaneously obtained in the time axis. By implementing temporal Fourier transform for spectroscopy applications, this time-lens-based architecture can provide orders of magnitude improvement over the state-of-art spatial-dispersion-based spectroscopy in terms of the frame rate. On the other hand, in addition to the single-lens structure, the multi-lens structures (e.g. telescope or wide-angle scope) will provide very versatile operating conditions. Leveraging the merit of instantaneous response, as well as the flexible lens structure, here we present a 100-MHz frame rate spectroscopy system - the parametric spectro-temporal analyzer (PASTA), which achieves 17 times zoom in/out ratio for different observation ranges.

Structured light enables biomimetic swimming and versatile locomotion of photoresponsive soft microrobots

NASA Astrophysics Data System (ADS)

Palagi, Stefano; Mark, Andrew G.; Reigh, Shang Yik; Melde, Kai; Qiu, Tian; Zeng, Hao; Parmeggiani, Camilla; Martella, Daniele; Sanchez-Castillo, Alberto; Kapernaum, Nadia; Giesselmann, Frank; Wiersma, Diederik S.; Lauga, Eric; Fischer, Peer

2016-06-01

Microorganisms move in challenging environments by periodic changes in body shape. In contrast, current artificial microrobots cannot actively deform, exhibiting at best passive bending under external fields. Here, by taking advantage of the wireless, scalable and spatiotemporally selective capabilities that light allows, we show that soft microrobots consisting of photoactive liquid-crystal elastomers can be driven by structured monochromatic light to perform sophisticated biomimetic motions. We realize continuum yet selectively addressable artificial microswimmers that generate travelling-wave motions to self-propel without external forces or torques, as well as microrobots capable of versatile locomotion behaviours on demand. Both theoretical predictions and experimental results confirm that multiple gaits, mimicking either symplectic or antiplectic metachrony of ciliate protozoa, can be achieved with single microswimmers. The principle of using structured light can be extended to other applications that require microscale actuation with sophisticated spatiotemporal coordination for advanced microrobotic technologies.

Directly transforming PCR-amplified DNA fragments into plant cells is a versatile system that facilitates the transient expression assay.

PubMed

Lu, Yuming; Chen, Xi; Wu, Yuxuan; Wang, Yanping; He, Yuqing; Wu, Yan

2013-01-01

A circular plasmid containing a gene coding sequence has been broadly used for studying gene regulation in cells. However, to accommodate a quick screen plasmid construction and preparation can be time consuming. Here we report a PCR amplified dsDNA fragments (PCR-fragments) based transient expression system (PCR-TES) for suiting in the study of gene regulation in plant cells. Instead of transforming plasmids into plant cells, transient expression of PCR-fragments can be applicable. The transformation efficiency and expression property of PCR-fragments are comparable to transformation using plasmids. We analyzed the transformation efficiency in PCR-TES at transcription and protein levels. Our results indicate that the PCR-TES is as versatile as the conventional transformation system using plasmid DNA. Through reconstituting PYR1-mediated ABA signaling pathway in Arabidopsis mesophyll protoplasts, we were not only validating the practicality of PCR-TES but also screening potential candidates of CDPK family members which might be involved in the ABA signaling. Moreover, we determined that phosphorylation of ABF2 by CPK4 could be mediated by ABA-induced PYR1 and ABI1, demonstrating a crucial role of CDPKs in the ABA signaling. In summary, PCR-TES can be applicable to facilitate analyzing gene regulation and for the screen of putative regulatory molecules at the high throughput level in plant cells.

Directly Transforming PCR-Amplified DNA Fragments into Plant Cells Is a Versatile System That Facilitates the Transient Expression Assay

PubMed Central

Lu, Yuming; Chen, Xi; Wu, Yuxuan; Wang, Yanping; He, Yuqing; Wu, Yan

2013-01-01

A circular plasmid containing a gene coding sequence has been broadly used for studying gene regulation in cells. However, to accommodate a quick screen plasmid construction and preparation can be time consuming. Here we report a PCR amplified dsDNA fragments (PCR-fragments) based transient expression system (PCR-TES) for suiting in the study of gene regulation in plant cells. Instead of transforming plasmids into plant cells, transient expression of PCR-fragments can be applicable. The transformation efficiency and expression property of PCR-fragments are comparable to transformation using plasmids. We analyzed the transformation efficiency in PCR-TES at transcription and protein levels. Our results indicate that the PCR-TES is as versatile as the conventional transformation system using plasmid DNA. Through reconstituting PYR1-mediated ABA signaling pathway in Arabidopsis mesophyll protoplasts, we were not only validating the practicality of PCR-TES but also screening potential candidates of CDPK family members which might be involved in the ABA signaling. Moreover, we determined that phosphorylation of ABF2 by CPK4 could be mediated by ABA-induced PYR1 and ABI1, demonstrating a crucial role of CDPKs in the ABA signaling. In summary, PCR-TES can be applicable to facilitate analyzing gene regulation and for the screen of putative regulatory molecules at the high throughput level in plant cells. PMID:23468926

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

Structural Sizing Methodology for the Tendon-Actuated Lightweight In-Space MANipulator (TALISMAN) System

NASA Technical Reports Server (NTRS)

Jones, Thomas C.; Dorsey, John T.; Doggett, William R.

2015-01-01

The Tendon-Actuated Lightweight In-Space MANipulator (TALISMAN) is a versatile long-reach robotic manipulator that is currently being tested at NASA Langley Research Center. TALISMAN is designed to be highly mass-efficient and multi-mission capable, with applications including asteroid retrieval and manipulation, in-space servicing, and astronaut and payload positioning. The manipulator uses a modular, periodic, tension-compression design that lends itself well to analytical modeling. Given the versatility of application for TALISMAN, a structural sizing methodology was developed that could rapidly assess mass and configuration sensitivities for any specified operating work space, applied loads and mission requirements. This methodology allows the systematic sizing of the key structural members of TALISMAN, which include the truss arm links, the spreaders and the tension elements. This paper summarizes the detailed analytical derivations and methodology that support the structural sizing approach and provides results from some recent TALISMAN designs developed for current and proposed mission architectures.

Selective 2'-hydroxyl acylation analyzed by primer extension and mutational profiling (SHAPE-MaP) for direct, versatile and accurate RNA structure analysis.

PubMed

Smola, Matthew J; Rice, Greggory M; Busan, Steven; Siegfried, Nathan A; Weeks, Kevin M

2015-11-01

Selective 2'-hydroxyl acylation analyzed by primer extension (SHAPE) chemistries exploit small electrophilic reagents that react with 2'-hydroxyl groups to interrogate RNA structure at single-nucleotide resolution. Mutational profiling (MaP) identifies modified residues by using reverse transcriptase to misread a SHAPE-modified nucleotide and then counting the resulting mutations by massively parallel sequencing. The SHAPE-MaP approach measures the structure of large and transcriptome-wide systems as accurately as can be done for simple model RNAs. This protocol describes the experimental steps, implemented over 3 d, that are required to perform SHAPE probing and to construct multiplexed SHAPE-MaP libraries suitable for deep sequencing. Automated processing of MaP sequencing data is accomplished using two software packages. ShapeMapper converts raw sequencing files into mutational profiles, creates SHAPE reactivity plots and provides useful troubleshooting information. SuperFold uses these data to model RNA secondary structures, identify regions with well-defined structures and visualize probable and alternative helices, often in under 1 d. SHAPE-MaP can be used to make nucleotide-resolution biophysical measurements of individual RNA motifs, rare components of complex RNA ensembles and entire transcriptomes.

Cyclodextrins as versatile building blocks for regenerative medicine.

PubMed

Alvarez-Lorenzo, Carmen; García-González, Carlos A; Concheiro, Angel

2017-12-28

Cyclodextrins (CDs) are one of the most versatile substances produced by nature, and it is in the aqueous biological environment where the multifaceted potential of CDs can be completely unveiled. CDs form inclusion complexes with a variety of guest molecules, including polymers, producing very diverse biocompatible supramolecular structures. Additionally, CDs themselves can trigger cell differentiation to distinct lineages depending on the substituent groups and also promote salt nucleation. These features together with the affinity-driven regulated release of therapeutic molecules, growth factors and gene vectors explain the rising interest for CDs as building blocks in regenerative medicine. Supramolecular poly(pseudo)rotaxane structures and zipper-like assemblies exhibit outstanding viscoelastic properties, performing as syringeable implants. The sharp shear-responsiveness of the supramolecular assemblies is opening new avenues for the design of bioinks for 3D printing and also of electrospun fibers. CDs can also be transformed into polymerizable monomers to prepare alternative nanostructured materials. The aim of this review is to analyze the role that CDs may play in regenerative medicine through the analysis of the last decade research. Most applications of CD-based scaffolds are focussed on non-healing bone fractures, cartilage reparation and skin recovery, but also on even more challenging demands such as neural grafts. For the sake of clarity, main sections of this review are organized according to the architecture of the CD-based scaffolds, mainly syringeable supramolecular hydrogels, 3D printed scaffolds, electrospun fibers, and composites, since the same scaffold type may find application in different tissues. Copyright © 2017 Elsevier B.V. All rights reserved.

Availability, diversification and versatility explain human selection of introduced plants in Ecuadorian traditional medicine

PubMed Central

Gaoue, Orou G.; de la Torre, Lucía; Navarrete, Hugo; Muriel, Priscilla; Macía, Manuel J.; Balslev, Henrik; León-Yánez, Susana; Jørgensen, Peter; Duffy, David Cameron

2017-01-01

Globally, a majority of people use plants as a primary source of healthcare and introduced plants are increasingly discussed as medicine. Protecting this resource for human health depends upon understanding which plants are used and how use patterns will change over time. The increasing use of introduced plants in local pharmacopoeia has been explained by their greater abundance or accessibility (availability hypothesis), their ability to cure medical conditions that are not treated by native plants (diversification hypothesis), or as a result of the introduced plants’ having many different simultaneous roles (versatility hypothesis). In order to describe the role of introduced plants in Ecuador, and to test these three hypotheses, we asked if introduced plants are over-represented in the Ecuadorian pharmacopoeia, and if their use as medicine is best explained by the introduced plants’ greater availability, different therapeutic applications, or greater number of use categories. Drawing on 44,585 plant-use entries, and the checklist of >17,000 species found in Ecuador, we used multi-model inference to test if more introduced plants are used as medicines in Ecuador than expected by chance, and examine the support for each of the three hypotheses above. We find nuanced support for all hypotheses. More introduced plants are utilized than would be expected by chance, which can be explained by geographic distribution, their strong association with cultivation, diversification (except with regard to introduced diseases), and therapeutic versatility, but not versatility of use categories. Introduced plants make a disproportionately high contribution to plant medicine in Ecuador. The strong association of cultivation with introduced medicinal plant use highlights the importance of the maintenance of human-mediated environments such as homegardens and agroforests for the provisioning of healthcare services. PMID:28886104

Development of internal magnetic probe for current density profile measurement in Versatile Experiment Spherical Torus

NASA Astrophysics Data System (ADS)

Yang, J.; Lee, J. W.; Jung, B. K.; Chung, K. J.; Hwang, Y. S.

2014-11-01

An internal magnetic probe using Hall sensors to measure a current density profile directly with perturbation of less than 10% to the plasma current is successfully operated for the first time in Versatile Experiment Spherical Torus (VEST). An appropriate Hall sensor is chosen to produce sufficient signals for VEST magnetic field while maintaining the small size of 10 mm in outer diameter. Temperature around the Hall sensor in a typical VEST plasma is regulated by blown air of 2 bars. First measurement of 60 kA VEST ohmic discharge shows a reasonable agreement with the total plasma current measured by Rogowski coil in VEST.

Crystal chemistry and the role of ionic radius in rare earth tetrasilicates: Ba2RE2Si4O12F2 (RE = Er3+-Lu3+) and Ba2RE2Si4O13 (RE = La3+-Ho3+).

PubMed

Fulle, Kyle; Sanjeewa, Liurukara D; McMillen, Colin D; Kolis, Joseph W

2017-10-01

Structural variations across a series of barium rare earth (RE) tetrasilicates are studied. Two different formulas are observed, namely those of a new cyclo-silicate fluoride, BaRE 2 Si 4 O 12 F 2 (RE = Er 3+ -Lu 3+ ) and new compounds in the Ba 2 RE 2 Si 4 O 13 (RE = La 3+ -Ho 3+ ) family, covering the whole range of ionic radii for the rare earth ions. The Ba 2 RE 2 Si 4 O 13 series is further subdivided into two polymorphs, also showing a dependence on rare earth ionic radius (space group P{\\overline 1} for La 3+ -Nd 3+ , and space group C2/c for Sm 3+ -Ho 3+ ). Two of the structure types identified are based on dinuclear rare earth units that differ in their crystal chemistries, particularly with respect to the role of fluorine as a structural director. The broad study of rare earth ions provides greater insight into understanding structural variations within silicate frameworks and the nature of f-block incorporation in oxyanion frameworks. The single crystals are grown from high-temperature (ca 953 K) hydrothermal fluids, demonstrating the versatility of the technique to access new phases containing recalcitrant rare earth oxides, enabling the study of structural trends.

A Versatile Class of Cell Surface Directional Motors Gives Rise to Gliding Motility and Sporulation in Myxococcus xanthus

PubMed Central

Wartel, Morgane; Czerwinski, Fabian; Le Gall, Anne-Valérie; Mauriello, Emilia M. F.; Bergam, Ptissam; Brun, Yves V.; Shaevitz, Joshua; Mignot, Tâm

2013-01-01

Eukaryotic cells utilize an arsenal of processive transport systems to deliver macromolecules to specific subcellular sites. In prokaryotes, such transport mechanisms have only been shown to mediate gliding motility, a form of microbial surface translocation. Here, we show that the motility function of the Myxococcus xanthus Agl-Glt machinery results from the recent specialization of a versatile class of bacterial transporters. Specifically, we demonstrate that the Agl motility motor is modular and dissociates from the rest of the gliding machinery (the Glt complex) to bind the newly expressed Nfs complex, a close Glt paralogue, during sporulation. Following this association, the Agl system transports Nfs proteins directionally around the spore surface. Since the main spore coat polymer is secreted at discrete sites around the spore surface, its transport by Agl-Nfs ensures its distribution around the spore. Thus, the Agl-Glt/Nfs machineries may constitute a novel class of directional bacterial surface transporters that can be diversified to specific tasks depending on the cognate cargo and machinery-specific accessories. PMID:24339744

ICAN: A versatile code for predicting composite properties

NASA Technical Reports Server (NTRS)

Ginty, C. A.; Chamis, C. C.

1986-01-01

The Integrated Composites ANalyzer (ICAN), a stand-alone computer code, incorporates micromechanics equations and laminate theory to analyze/design multilayered fiber composite structures. Procedures for both the implementation of new data in ICAN and the selection of appropriate measured data are summarized for: (1) composite systems subject to severe thermal environments; (2) woven fabric/cloth composites; and (3) the selection of new composite systems including those made from high strain-to-fracture fibers. The comparisons demonstrate the versatility of ICAN as a reliable method for determining composite properties suitable for preliminary design.

A Versatile Rocket Engine Hot Gas Facility

NASA Technical Reports Server (NTRS)

Green, James M.

1993-01-01

The capabilities of a versatile rocket engine facility, located in the Rocket Laboratory at the NASA Lewis Research Center, are presented. The gaseous hydrogen/oxygen facility can be used for thermal shock and hot gas testing of materials and structures as well as rocket propulsion testing. Testing over a wide range of operating conditions in both fuel and oxygen rich regimes can be conducted, with cooled or uncooled test specimens. The size and location of the test cell provide the ability to conduct large amounts of testing in short time periods with rapid turnaround between programs.

The role of water molecules in computational drug design.

PubMed

de Beer, Stephanie B A; Vermeulen, Nico P E; Oostenbrink, Chris

2010-01-01

Although water molecules are small and only consist of two different atom types, they play various roles in cellular systems. This review discusses their influence on the binding process between biomacromolecular targets and small molecule ligands and how this influence can be modeled in computational drug design approaches. Both the structure and the thermodynamics of active site waters will be discussed as these influence the binding process significantly. Structurally conserved waters cannot always be determined experimentally and if observed, it is not clear if they will be replaced upon ligand binding, even if sufficient space is available. Methods to predict the presence of water in protein-ligand complexes will be reviewed. Subsequently, we will discuss methods to include water in computational drug research. Either as an additional factor in automated docking experiments, or explicitly in detailed molecular dynamics simulations, the effect of water on the quality of the simulations is significant, but not easily predicted. The most detailed calculations involve estimates of the free energy contribution of water molecules to protein-ligand complexes. These calculations are computationally demanding, but give insight in the versatility and importance of water in ligand binding.

Carotenoids, versatile components of oxygenic photosynthesis.

PubMed

Domonkos, Ildikó; Kis, Mihály; Gombos, Zoltán; Ughy, Bettina

2013-10-01

Carotenoids (CARs) are a group of pigments that perform several important physiological functions in all kingdoms of living organisms. CARs serve as protective agents, which are essential structural components of photosynthetic complexes and membranes, and they play an important role in the light harvesting mechanism of photosynthesizing plants and cyanobacteria. The protection against reactive oxygen species, realized by quenching of singlet oxygen and the excited states of photosensitizing molecules, as well as by the scavenging of free radicals, is one of the main biological functions of CARs. X-ray crystallographic localization of CARs revealed that they are present at functionally and structurally important sites of both the PSI and PSII reaction centers. Characterization of a CAR-less cyanobacterial mutant revealed that while the absence of CARs prevents the formation of PSII complexes, it does not abolish the assembly and function of PSI. CAR molecules assist in the formation of protein subunits of the photosynthetic complexes by gluing together their protein components. In addition to their aforementioned indispensable functions, CARs have a substantial role in the formation and maintenance of proper cellular architecture, and potentially also in the protection of the translational machinery under stress conditions. Copyright © 2013 Elsevier Ltd. All rights reserved.

Chemical and Conformational Diversity of Modified Nucleosides Affects tRNA Structure and Function.

PubMed

Väre, Ville Y P; Eruysal, Emily R; Narendran, Amithi; Sarachan, Kathryn L; Agris, Paul F

2017-03-16

RNAs are central to all gene expression through the control of protein synthesis. Four major nucleosides, adenosine, guanosine, cytidine and uridine, compose RNAs and provide sequence variation, but are limited in contributions to structural variation as well as distinct chemical properties. The ability of RNAs to play multiple roles in cellular metabolism is made possible by extensive variation in length, conformational dynamics, and the over 100 post-transcriptional modifications. There are several reviews of the biochemical pathways leading to RNA modification, but the physicochemical nature of modified nucleosides and how they facilitate RNA function is of keen interest, particularly with regard to the contributions of modified nucleosides. Transfer RNAs (tRNAs) are the most extensively modified RNAs. The diversity of modifications provide versatility to the chemical and structural environments. The added chemistry, conformation and dynamics of modified nucleosides occurring at the termini of stems in tRNA's cloverleaf secondary structure affect the global three-dimensional conformation, produce unique recognition determinants for macromolecules to recognize tRNAs, and affect the accurate and efficient decoding ability of tRNAs. This review will discuss the impact of specific chemical moieties on the structure, stability, electrochemical properties, and function of tRNAs.

Statistical Mechanics of the Cytoskeleton

NASA Astrophysics Data System (ADS)

Wang, Shenshen

The mechanical integrity of eukaryotic cells along with their capability of dynamic remodeling depends on their cytoskeleton, a structural scaffold made up of a complex and dense network of filamentous proteins spanning the cytoplasm. Active force generation within the cytoskeletal networks by molecular motors is ultimately powered by the consumption of chemical energy and conversion of that energy into mechanical work. The resulting functional movements range from the collective cell migration in epithelial tissues responsible for wound healing to the changes of cell shape that occur during muscle contraction, as well as all the internal structural rearrangements essential for cell division. The role of the cytoskeleton as a dynamic versatile mesoscale "muscle", whose passive and active performance is both highly heterogeneous in space and time and intimately linked to diverse biological functions, allows it to serve as a sensitive indicator for the health and developmental state of the cell. By approaching this natural nonequilibrium many-body system from a variety of perspectives, researchers have made major progress toward understanding the cytoskeleton's unusual mechanical, dynamical and structural properties. Yet a unifying framework capable of capturing both the dynamics of active pattern formation and the emergence of spontaneous collective motion, that allows one to predict the dependence of the model's control parameters on motor properties, is still needed. In the following we construct a microscopic model and provide a theoretical framework to investigate the intricate interplay between local force generation, network architecture and collective motor action. This framework is able to accommodate both regular and heterogeneous pattern formation, as well as arrested coarsening and macroscopic contraction in a unified manner, through the notion of motor-driven effective interactions. Moreover a systematic expansion scheme combined with a variational stability analysis yields a threshold strength of motor kicking noise, below which the motorized system behaves as if it were at an effective equilibrium, but with a nontrivial effective temperature. Above the threshold, however, collective directed motion emerges spontaneously. Computer simulations support the theoretical predictions and highlight the essential role played in large-scale contraction by spatial correlation in motor kicking events.

BLISS is a versatile and quantitative method for genome-wide profiling of DNA double-strand breaks.

PubMed

Yan, Winston X; Mirzazadeh, Reza; Garnerone, Silvano; Scott, David; Schneider, Martin W; Kallas, Tomasz; Custodio, Joaquin; Wernersson, Erik; Li, Yinqing; Gao, Linyi; Federova, Yana; Zetsche, Bernd; Zhang, Feng; Bienko, Magda; Crosetto, Nicola

2017-05-12

Precisely measuring the location and frequency of DNA double-strand breaks (DSBs) along the genome is instrumental to understanding genomic fragility, but current methods are limited in versatility, sensitivity or practicality. Here we present Breaks Labeling In Situ and Sequencing (BLISS), featuring the following: (1) direct labelling of DSBs in fixed cells or tissue sections on a solid surface; (2) low-input requirement by linear amplification of tagged DSBs by in vitro transcription; (3) quantification of DSBs through unique molecular identifiers; and (4) easy scalability and multiplexing. We apply BLISS to profile endogenous and exogenous DSBs in low-input samples of cancer cells, embryonic stem cells and liver tissue. We demonstrate the sensitivity of BLISS by assessing the genome-wide off-target activity of two CRISPR-associated RNA-guided endonucleases, Cas9 and Cpf1, observing that Cpf1 has higher specificity than Cas9. Our results establish BLISS as a versatile, sensitive and efficient method for genome-wide DSB mapping in many applications.

Versatile strain-tuning of modulated long-period magnetic structures

DOE PAGES

Fobes, D. M.; Luo, Yongkang; León-Brito, N.; ...

2017-05-10

In this paper, we report a detailed small-angle neutron scattering (SANS) study of the skyrmion lattice phase of MnSi under compressive and tensile strain. In particular, we demonstrate that tensile strain applied to the skyrmion lattice plane, perpendicular to the magnetic field, acts to destabilize the skyrmion lattice phase. Finally, this experiment was enabled by our development of a versatile strain cell, unique in its ability to select the application of either tensile or compressive strain in-situ by using two independent helium-actuated copper pressure transducers, whose design has been optimized for magnetic SANS on modulated long-period magnetic structures and vortexmore » lattices, and is compact enough to fit in common sample environments such as cryostats and superconducting magnets.« less

Isoforms, structures, and functions of versatile spectraplakin MACF1.

PubMed

Hu, Lifang; Su, Peihong; Li, Runzhi; Yin, Chong; Zhang, Yan; Shang, Peng; Yang, Tuanmin; Qian, Airong

2016-01-01

Spectraplakins are crucially important communicators, linking cytoskeletal components to each other and cellular junctions. Microtubule actin crosslinking factor 1 (MACF1), also known as actin crosslinking family 7 (ACF7), is a member of the spectraplakin family. It is expressed in numerous tissues and cells as one extensively studied spectraplakin. MACF1 has several isoforms with unique structures and well-known function to be able to crosslink F-actin and microtubules. MACF1 is one versatile spectraplakin with various functions in cell processes, embryo development, tissue-specific functions, and human diseases. The importance of MACF1 has become more apparent in recent years. Here, we summarize the current knowledge on the presence and function of MACF1 and provide perspectives on future research of MACF1 based on our studies and others.

Aeroelastic Analysis Of Versatile Thermal Insulation Panels For Launchers Applications

NASA Astrophysics Data System (ADS)

Carrera, E.; Zappino, E.; Augello, G.; Ferrarese, A.; Montabone, M.

2011-05-01

The aeroelastic behavior of a Versatile Thermal Insulation (VTI) has been investigated. Among the various loadings acting on the panels in this work the attention is payed to fluid structure interaction. e.g. panel flutter phenomena. Known available results from open literature, related to similar problems, permit to analyze the effect of various Mach regimes, including boundary layers thickness effects, in-plane mechanical and thermal loadings, nonlinear effect and amplitude of so called limit cycle oscillations. Dedicated finite element model is developed for the supersonic regime. The model used for coupling orthotropic layered structural model with to Piston Theory aerodynamic models allows the calculations of flutter conditions in case of curved panels supported in a dis- crete number of points. Through this approach the flutter boundaries of the VTI-panel have been investigated.

Handedness is a biomarker of variation in anal sex role behavior and Recalled Childhood Gender Nonconformity among gay men.

PubMed

Swift-Gallant, Ashlyn; Coome, Lindsay A; Monks, D Ashley; VanderLaan, Doug P

2017-01-01

Developmental theories of the biological basis of sexual orientation suggest that sexually differentiated psychological and behavioural traits should be linked with sexual orientation. Subgroups of gay men delineated by anal sex roles differ according to at least one such trait: gender expression. The present study assessed the hypothesis that handedness, a biologically determined sexually differentiated trait, corresponds to differences in subgroups of gay men based on anal sex role. Furthermore, it assessed whether handedness mediates the association between gender nonconformity and male sexual orientation. Straight and gay men (N = 333) completed the Edinburgh Inventory of Handedness and the Recalled Childhood Gender Nonconformity Scale. Gay men also completed measures of anal sex role preference. As in previous studies, gay men showed greater non-right-handedness and gender nonconformity than straight men. Also, among gay men, bottoms/versatiles (i.e., gay men who take a receptive anal sex role, or who take on both a receptive and insertive anal sex role) were more gender-nonconforming than tops (i.e., gay men who take an insertive anal sex role). In support of the hypothesis, bottoms/versatiles were more non-right-handed than tops and handedness mediated the male sexual orientation and anal sex role differences in Recalled Childhood Gender Nonconformity. Together, these findings suggest that developmental processes linked to handedness underpin variation among men in sexual orientation and gender nonconformity as well as variation among subgroups of gay men that are delineated by anal sex roles.

The Hippo pathway in intestinal regeneration and disease.

PubMed

Hong, Audrey W; Meng, Zhipeng; Guan, Kun-Liang

2016-06-01

The Hippo pathway is a signalling cascade conserved from Drosophila melanogaster to mammals. The mammalian core kinase components comprise MST1 and MST2, SAV1, LATS1 and LATS2 and MOB1A and MOB1B. The transcriptional co-activators YAP1 and TAZ are the downstream effectors of the Hippo pathway and regulate target gene expression. Hippo signalling has crucial roles in the control of organ size, tissue homeostasis and regeneration, and dysregulation of the Hippo pathway can lead to uncontrolled cell growth and malignant transformation. Mammalian intestine consists of a stem cell compartment as well as differentiated cells, and its ability to regenerate rapidly after injury makes it an excellent model system to study tissue homeostasis, regeneration and tumorigenesis. Several studies have established the important role of the Hippo pathway in these processes. In addition, crosstalk between Hippo and other signalling pathways provides tight, yet versatile, regulation of tissue homeostasis. In this Review, we summarize studies on the role of the Hippo pathway in the intestine on these physiological processes and the underlying mechanisms responsible, and discuss future research directions and potential therapeutic strategies targeting Hippo signalling in intestinal disease.

The Hippo pathway in intestinal regeneration and disease

PubMed Central

Hong, Audrey W.; Meng, Zhipeng; Guan, Kun-Liang

2017-01-01

The Hippo pathway is a signalling cascade conserved from Drosophila melanogaster to mammals. The mammalian core kinase components comprise MST1 and MST2, SAV1, LATS1 and LATS2 and MOB1A and MOB1B. The transcriptional co-activators YAP1 and TAZ are the downstream effectors of the Hippo pathway and regulate target gene expression. Hippo signalling has crucial roles in the control of organ size, tissue homeostasis and regeneration, and dysregulation of the Hippo pathway can lead to uncontrolled cell growth and malignant transformation. Mammalian intestine consists of a stem cell compartment as well as differentiated cells, and its ability to regenerate rapidly after injury makes it an excellent model system to study tissue homeostasis, regeneration and tumorigenesis. Several studies have established the important role of the Hippo pathway in these processes. In addition, crosstalk between Hippo and other signalling pathways provides tight, yet versatile, regulation of tissue homeostasis. In this Review, we summarize studies on the role of the Hippo pathway in the intestine on these physiological processes and the underlying mechanisms responsible, and discuss future research directions and potential therapeutic strategies targeting Hippo signalling in intestinal disease. PMID:27147489

[The benefits of doing excercise in the elderly].

PubMed

Avila-Funes, José Alberto; García-Mayo, Emilio José

2004-01-01

Advanced age is associated with changes in body composition such as muscular mass loss, which is defined as sarcopenia. The former term plays a key role in the frailty model, although its source is unknown. Myriad strategies have been used to improve and increase muscular mass and function in older persons. The muscle is a versatile system that owes its great capacity to adaption to regular exercise programs. Aerobic exercise and resistance training improve muscular function and can minimize and even reverse sarcopenia in the elderly (healthy, very elderly or frail). The main difference in prescribing exercise for healthy adults and elderly individuals is that intensity of training program is lower for the latter. This review is aimed toward the physiopathologic aspects and clinical implications regarding muscular mass loss and to programs directed toward increasing strength and/or endurance in the elderly.

Magnetic Alignment of Block Copolymer Microdomains by Intrinsic Chain Anisotropy.

PubMed

Rokhlenko, Yekaterina; Gopinadhan, Manesh; Osuji, Chinedum O; Zhang, Kai; O'Hern, Corey S; Larson, Steven R; Gopalan, Padma; Majewski, Paweł W; Yager, Kevin G

2015-12-18

We examine the role of intrinsic chain susceptibility anisotropy in magnetic field directed self-assembly of a block copolymer using in situ x-ray scattering. Alignment of a lamellar mesophase is observed on cooling across the disorder-order transition with the resulting orientational order inversely proportional to the cooling rate. We discuss the origin of the susceptibility anisotropy, Δχ, that drives alignment and calculate its magnitude using coarse-grained molecular dynamics to sample conformations of surface-tethered chains, finding Δχ≈2×10^{-8}. From field-dependent scattering data, we estimate that grains of ≈1.2  μm are present during alignment. These results demonstrate that intrinsic anisotropy is sufficient to support strong field-induced mesophase alignment and suggest a versatile strategy for field control of orientational order in block copolymers.

A Low Cost Structurally Optimized Design for Diverse Filter Types

PubMed Central

Kazmi, Majida; Aziz, Arshad; Akhtar, Pervez; Ikram, Nassar

2016-01-01

A wide range of image processing applications deploys two dimensional (2D)-filters for performing diversified tasks such as image enhancement, edge detection, noise suppression, multi scale decomposition and compression etc. All of these tasks require multiple type of 2D-filters simultaneously to acquire the desired results. The resource hungry conventional approach is not a viable option for implementing these computationally intensive 2D-filters especially in a resource constraint environment. Thus it calls for optimized solutions. Mostly the optimization of these filters are based on exploiting structural properties. A common shortcoming of all previously reported optimized approaches is their restricted applicability only for a specific filter type. These narrow scoped solutions completely disregard the versatility attribute of advanced image processing applications and in turn offset their effectiveness while implementing a complete application. This paper presents an efficient framework which exploits the structural properties of 2D-filters for effectually reducing its computational cost along with an added advantage of versatility for supporting diverse filter types. A composite symmetric filter structure is introduced which exploits the identities of quadrant and circular T-symmetries in two distinct filter regions simultaneously. These T-symmetries effectually reduce the number of filter coefficients and consequently its multipliers count. The proposed framework at the same time empowers this composite filter structure with additional capabilities of realizing all of its Ψ-symmetry based subtypes and also its special asymmetric filters case. The two-fold optimized framework thus reduces filter computational cost up to 75% as compared to the conventional approach as well as its versatility attribute not only supports diverse filter types but also offers further cost reduction via resource sharing for sequential implementation of diversified image processing applications especially in a constraint environment. PMID:27832133

Integration of plant viruses in electron beam lithography nanostructures.

PubMed

Alonso, Jose M; Ondarçuhu, Thierry; Bittner, Alexander M

2013-03-15

Tobacco mosaic virus (TMV) is the textbook example of a virus, and also of a self-assembling nanoscale structure. This tubular RNA/protein architecture has also found applications as biotemplate for the synthesis of nanomaterials such as wires, as tubes, or as nanoparticle assemblies. Although TMV is, being a biological structure, quite resilient to environmental conditions (temperature, chemicals), it cannot be processed in electron beam lithography (eBL) fabrication, which is the most important and most versatile method of nanoscale structuring. Here we present adjusted eBL-compatible processes that allow the incorporation of TMV in nanostructures made of positive and negative tone eBL resists. The key steps are covering TMV by polymer resists, which are only heated to 50 °C, and development (selective dissolution) in carefully selected organic solvents. We demonstrate the post-lithography biochemical functionality of TMV by selective immunocoating of the viral particles, and the use of immobilized TMV as direct immunosensor. Our modified eBL process should be applicable to incorporate a wide range of sensitive materials in nanofabrication schemes.

UNIX and healthcare systems: a good marriage.

PubMed

Wieners, W

1992-08-01

Powerful and versatile, UNIX makes open systems affordable in today's complex healthcare marketplace. As more emphasis is placed on combining the best systems for the least money, UNIX plays an important role. How many hospitals are using it already?

Using the Structured Product Labeling format to index versatile chemical data (ACS Spring meeting)

EPA Science Inventory

Structured Product Labeling (SPL) is a document markup standard approved by the Health Level Seven (HL7) standards organization and adopted by the FDA as a mechanism for exchanging product and facility information. Product information provided by companies in SPL format may be ac...

Structured-illumination reflectance imaging coupled with spiral phase transform for bruise detection and three-dimensional geometry reconstruction of apples

USDA-ARS?s Scientific Manuscript database

Structured-illumination reflectance imaging (SIRI) is a new, promising imaging technique with enhanced, versatile capabilities for quality evaluation of food products. SIRI enables simultaneous acquisition of higher-contrast/resolution and better depth-controlled intensity and phase images for detec...

Contactless, photoinitiated snap-through in azobenzene-functionalized polymers

PubMed Central

Shankar, M. Ravi; Smith, Matthew L.; Tondiglia, Vincent P.; Lee, Kyung Min; McConney, Michael E.; Wang, David H.; Tan, Loon-Seng; White, Timothy J.

2013-01-01

Photomechanical effects in polymeric materials and composites transduce light into mechanical work. The ability to control the intensity, polarization, placement, and duration of light irradiation is a distinctive and potentially useful tool to tailor the location, magnitude, and directionality of photogenerated mechanical work. Unfortunately, the work generated from photoresponsive materials is often slow and yields very small power densities, which diminish their potential use in applications. Here, we investigate photoinitiated snap-through in bistable arches formed from samples composed of azobenzene-functionalized polymers (both amorphous polyimides and liquid crystal polymer networks) and report orders-of-magnitude enhancement in actuation rates (approaching 102 mm/s) and powers (as much as 1 kW/m3). The contactless, ultra-fast actuation is observed at irradiation intensities <<100 mW/cm2. Due to the bistability and symmetry of the snap-through, reversible and bidirectional actuation is demonstrated. A model is developed to elucidate the underlying mechanics of the snap-through, specifically focusing on isolating the role of sample geometry, mechanical properties of the materials, and photomechanical strain. Using light to trigger contactless, ultrafast actuation in an otherwise passive structure is a potentially versatile tool to use in mechanical design at the micro-, meso-, and millimeter scales as actuators, as well as switches that can be triggered from large standoff distances, impulse generators for microvehicles, microfluidic valves and mixers in laboratory-on-chip devices, and adaptive optical elements. PMID:24190994

Overcoming Biological, Behavioral and Structural Vulnerabilities: New Directions in Research to Decrease HIV Transmission in Men who have Sex with Men

PubMed Central

Wheeler, Darrell P.; Bekker, Linda-Gail; Grinsztejn, Beatriz; Remien, Robert H.; Sandfort, Theodorus G. M.; Beyrer, Chris

2013-01-01

Men who have sex with men, including transgender women, comprise a heterogeneous group of individuals, whose sexual behaviors and gender identities may varying widely between cultures and among individuals. Their sources of increased vulnerability to HIV are diverse, including the increased efficiency of HIV transmission via unprotected anal intercourse, sexual role versatility, asymptomatic sexually transmitted infections, as well as behavioral factors that may be associated with condomless sex with multiple partners. Societal stigmatization of homosexual behavior and gender non-conformity may result in internalized negative feelings that lead to depression, other affective disorders, and substance use, which in turn are associated with increased risk taking behaviors. Social stigma and punitive civil environments may lead to delays in seeking HIV and STD screening, and later initiation of antiretroviral therapy. The iPrEX study demonstrated that chemoprophylaxis can decrease HIV acquisition in MSM, and the HPTN 052 study established the biological plausibility that earlier initiation of HAART can decrease HIV transmission to uninfected partners. Despite these advances, MSM remain among the most significantly HIV-affected population in resource rich and limited settings. New studies will integrate enhanced understanding of the biology of enhanced rectal transmission of HIV and the focused use of antiretrovirals for prevention with culturally-tailored approaches that address the potentiating social and behavioral factors associated with enhanced HIV spread among MSM. PMID:23764630

Building a Three-Dimensional Nano-Bio Interface for Aptasensing: An Analytical Methodology Based on Steric Hindrance Initiated Signal Amplification Effect.

PubMed

Du, Xiaojiao; Jiang, Ding; Hao, Nan; Qian, Jing; Dai, Liming; Zhou, Lei; Hu, Jianping; Wang, Kun

2016-10-04

The development of novel detection methodologies in electrochemiluminescence (ECL) aptasensor fields with simplicity and ultrasensitivity is essential for constructing biosensing architectures. Herein, a facile, specific, and sensitive methodology was developed unprecedentedly for quantitative detection of microcystin-LR (MC-LR) based on three-dimensional boron and nitrogen codoped graphene hydrogels (BN-GHs) assisted steric hindrance amplifying effect between the aptamer and target analytes. The recognition reaction was monitored by quartz crystal microbalance (QCM) to validate the possible steric hindrance effect. First, the BN-GHs were synthesized via self-assembled hydrothermal method and then applied as the Ru(bpy) 3 2+ immobilization platform for further loading the biomolecule aptamers due to their nanoporous structure and large specific surface area. Interestingly, we discovered for the first time that, without the aid of conventional double-stranded DNA configuration, such three-dimensional nanomaterials can directly amplify the steric hindrance effect between the aptamer and target analytes to a detectable level, and this facile methodology could be for an exquisite assay. With the MC-LR as a model, this novel ECL biosensor showed a high sensitivity and a wide linear range. This strategy supplies a simple and versatile platform for specific and sensitive determination of a wide range of aptamer-related targets, implying that three-dimensional nanomaterials would play a crucial role in engineering and developing novel detection methodologies for ECL aptasensing fields.

Contactless, photoinitiated snap-through in azobenzene-functionalized polymers.

PubMed

Shankar, M Ravi; Smith, Matthew L; Tondiglia, Vincent P; Lee, Kyung Min; McConney, Michael E; Wang, David H; Tan, Loon-Seng; White, Timothy J

2013-11-19

Photomechanical effects in polymeric materials and composites transduce light into mechanical work. The ability to control the intensity, polarization, placement, and duration of light irradiation is a distinctive and potentially useful tool to tailor the location, magnitude, and directionality of photogenerated mechanical work. Unfortunately, the work generated from photoresponsive materials is often slow and yields very small power densities, which diminish their potential use in applications. Here, we investigate photoinitiated snap-through in bistable arches formed from samples composed of azobenzene-functionalized polymers (both amorphous polyimides and liquid crystal polymer networks) and report orders-of-magnitude enhancement in actuation rates (approaching 10(2) mm/s) and powers (as much as 1 kW/m(3)). The contactless, ultra-fast actuation is observed at irradiation intensities <100 mW/cm(2). Due to the bistability and symmetry of the snap-through, reversible and bidirectional actuation is demonstrated. A model is developed to elucidate the underlying mechanics of the snap-through, specifically focusing on isolating the role of sample geometry, mechanical properties of the materials, and photomechanical strain. Using light to trigger contactless, ultrafast actuation in an otherwise passive structure is a potentially versatile tool to use in mechanical design at the micro-, meso-, and millimeter scales as actuators, as well as switches that can be triggered from large standoff distances, impulse generators for microvehicles, microfluidic valves and mixers in laboratory-on-chip devices, and adaptive optical elements.

Interface for Light-Driven Electron Transfer by Photosynthetic Complexes Across Block Copolymer Membranes.

PubMed

Kuang, Liangju; Olson, Tien L; Lin, Su; Flores, Marco; Jiang, Yunjiang; Zheng, Wan; Williams, JoAnn C; Allen, James P; Liang, Hongjun

2014-03-06

Incorporation of membrane proteins into nanodevices to mediate recognition and transport in a collective and scalable fashion remains a challenging problem. We demonstrate how nanoscale photovoltaics could be designed using robust synthetic nanomembranes with incorporated photosynthetic reaction centers (RCs). Specifically, RCs from Rhodobacter sphaeroides are reconstituted spontaneously into rationally designed polybutadiene membranes to form hierarchically organized proteopolymer membrane arrays via a charge-interaction-directed reconstitution mechanism. Once incorporated, the RCs are fully active for prolonged periods based upon a variety of spectroscopic measurements, underscoring preservation of their 3D pigment configuration critical for light-driven charge transfer. This result provides a strategy to construct solar conversion devices using structurally versatile proteopolymer membranes with integrated RC functions to harvest broad regions of the solar spectrum.

Multiple orbital angular momentum generated by dielectric hybrid phase element

NASA Astrophysics Data System (ADS)

Wang, Xuewen; Kuchmizhak, Aleksandr; Hu, Dejiao; Li, Xiangping

2017-09-01

Vortex beam carrying multiple orbital angular momentum provides a new degree of freedom to manipulate light leading to the various exciting applications as trapping, quantum optics, information multiplexing, etc. Helical wavefront can be generated either via the geometric or the dynamic phase arising from a space-variant birefringence (q-plate) or from phase accumulation through propagation (spiral-phase-plate), respectively. Using fast direct laser writing technique we fabricate and characterize novel hybrid q-plate generating vortex beam simultaneously carrying two different high-order topological charges, which arise from the spin-orbital conversion and the azimuthal height variation of the recorded structures. We approve the versatile concept to generate multiple-OAM vortex beams combining the spin-orbital interaction and the phase accumulation in a single micro-scale device, a hybrid dielectric phase plate.

Engineering topological phases in the Luttinger semimetal α -Sn

NASA Astrophysics Data System (ADS)

Zhang, Dongqin; Wang, Huaiqiang; Ruan, Jiawei; Yao, Ge; Zhang, Haijun

2018-05-01

α -Sn is well known as a typical Luttinger semimetal with a quadratic band touching at the Γ point. Based on the effective k .p analysis as well as first-principles calculations, we demonstrate that multiple topological phases with a rich diagram, including topological insulator, Dirac semimetal, and Weyl semimetal phases, can be induced and engineered in α -Sn by external strains, magnetic fields, and circularly polarized light (CPL). Intriguingly, not only the conventional type-I Weyl nodes but also type-II Weyl nodes and double-Weyl nodes can be generated directly from the quadratic semimetal by applying a magnetic field or CPL. Our results apply equally well to other Luttinger semimetals with similar crystal and electronic structures, and thus open an avenue for realizing and engineering multiple topological phases on a versatile platform.

Spherical-earth Gravity and Magnetic Anomaly Modeling by Gauss-legendre Quadrature Integration

NASA Technical Reports Server (NTRS)

Vonfrese, R. R. B.; Hinze, W. J.; Braile, L. W.; Luca, A. J. (Principal Investigator)

1981-01-01

The anomalous potential of gravity and magnetic fields and their spatial derivatives on a spherical Earth for an arbitrary body represented by an equivalent point source distribution of gravity poles or magnetic dipoles were calculated. The distribution of equivalent point sources was determined directly from the coordinate limits of the source volume. Variable integration limits for an arbitrarily shaped body are derived from interpolation of points which approximate the body's surface envelope. The versatility of the method is enhanced by the ability to treat physical property variations within the source volume and to consider variable magnetic fields over the source and observation surface. A number of examples verify and illustrate the capabilities of the technique, including preliminary modeling of potential field signatures for Mississippi embayment crustal structure at satellite elevations.

Mini Heme-Proteins: Designability of Structure and Diversity of Functions.

PubMed

Rai, Jagdish

2017-08-30

Natural heme proteins may have heme bound to poly-peptide chain as a cofactor via noncovalent forces or heme as a prosthetic group may be covalently bound to the proteins. Nature has used porphyrins in diverse functions like electron transfer, oxidation, reduction, ligand binding, photosynthesis, signaling, etc. by modulating its properties through diverse protein matrices. Synthetic chemists have tried to utilize these molecules in equally diverse industrial and medical applications due to their versatile electro-chemical and optical properties. The heme iron has catalytic activity which can be modulated and enhanced for specific applications by protein matrix around it. Heme proteins can be designed into novel enzymes for sterio specific catalysis ranging from oxidation to reduction. These designed heme-proteins can have applications in industrial catalysis and biosensing. A peptide folds around heme easily due to hydrophobic effect of the large aromatic ring of heme. The directional property of co-ordinate bonding between peptide and metal ion in heme further specifies the structure. Therefore heme proteins can be easily designed for targeted structure and catalytic activity. The central aromatic chemical entity in heme viz. porphyrin is a very ancient molecule. Its presence in the prebiotic soup and in all forms of life suggests that it has played a vital role in the origin and progressive evolution of living organisms. Porphyrin macrocycles are highly conjugated systems composed of four modified pyrrole subunits interconnected at their α -carbon atoms via methine (=CH-) bridges. Initial minimalist models of hemoproteins focused on effect of heme-ligand co-ordinate bonding on chemical reactivity, spectroscopy, electrochemistry and magnetic properties of heme. The great sensitivity of these spectroscopic features of heme to its surrounding makes them extremely useful in structural elucidation of designed heme-peptide complexes. Therefore heme proteins are easier to work on for designing novel proteins for industrial and medical applications. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Ligninolytic peroxidase genes in the oyster mushroom genome: heterologous expression, molecular structure, catalytic and stability properties, and lignin-degrading ability

PubMed Central

2014-01-01

Background The genome of Pleurotus ostreatus, an important edible mushroom and a model ligninolytic organism of interest in lignocellulose biorefineries due to its ability to delignify agricultural wastes, was sequenced with the purpose of identifying and characterizing the enzymes responsible for lignin degradation. Results Heterologous expression of the class II peroxidase genes, followed by kinetic studies, enabled their functional classification. The resulting inventory revealed the absence of lignin peroxidases (LiPs) and the presence of three versatile peroxidases (VPs) and six manganese peroxidases (MnPs), the crystal structures of two of them (VP1 and MnP4) were solved at 1.0 to 1.1 Å showing significant structural differences. Gene expansion supports the importance of both peroxidase types in the white-rot lifestyle of this fungus. Using a lignin model dimer and synthetic lignin, we showed that VP is able to degrade lignin. Moreover, the dual Mn-mediated and Mn-independent activity of P. ostreatus MnPs justifies their inclusion in a new peroxidase subfamily. The availability of the whole POD repertoire enabled investigation, at a biochemical level, of the existence of duplicated genes. Differences between isoenzymes are not limited to their kinetic constants. Surprising differences in their activity T50 and residual activity at both acidic and alkaline pH were observed. Directed mutagenesis and spectroscopic/structural information were combined to explain the catalytic and stability properties of the most interesting isoenzymes, and their evolutionary history was analyzed in the context of over 200 basidiomycete peroxidase sequences. Conclusions The analysis of the P. ostreatus genome shows a lignin-degrading system where the role generally played by LiP has been assumed by VP. Moreover, it enabled the first characterization of the complete set of peroxidase isoenzymes in a basidiomycete, revealing strong differences in stability properties and providing enzymes of biotechnological interest. PMID:24387130

Direct and indirect light emissions from layered ReS2-x Se x (0 ≤ x ≤ 2)

NASA Astrophysics Data System (ADS)

Ho, Ching-Hwa; Liu, Zhan-Zhi; Lin, Min-Han

2017-06-01

ReS2 and ReSe2 have recently been enthusiastically studied owing to the specific in-plane electrical, optical and structural anisotropy caused by their distorted one-layer trigonal (1 T) phase, whereas other traditional transition-metal dichalcogenides (TMDCs, e.g. MoS2 and WSe2) have a hexagonal structure. Because of this special property, more and versatile nano-electronics and nano-optoelectronics devices can be developed. In this work, 2D materials in the series ReS2-x Se x (0 ≤ x ≤ 2) have been successfully grown by the method of chemical vapor transport. The direct and indirect resonant emissions of the complete series of layers can be simultaneously detected by polarized micro-photoluminescence (μPL) spectroscopy when the thickness of the ReS2-x Se x is greater than ˜70 nm. When it is less than 70 nm, only three direct excitonic emissions—E 1 ex, E 2 ex and E S ex—are detected. For the thick (bulk) ReS2-x Se x , more stacking of the ReX2 monolayers even flattens and shifts the valence-band maximum from Γ to the other K- or M-related points, thus leading to the coexistence of direct and indirect resonant light emissions from the c-plane ReX2. The transmittance absorption edge of each bulk ReX2 (a few microns thick) usually has a lower energy than those of the direct E 1 ex and E 2 ex excitonic emissions to form indirect absorption. The coexistence of direct and indirect emissions in ReX2 is a unique characteristic of a 2D layered semiconductor possessing triclinic low symmetry.

Nanoimprint-Assisted Shear Exfoliation (NASE) for Producing Multilayer MoS2 Structures as Field-Effect Transistor Channel Arrays.

PubMed

Chen, Mikai; Nam, Hongsuk; Rokni, Hossein; Wi, Sungjin; Yoon, Jeong Seop; Chen, Pengyu; Kurabayashi, Katsuo; Lu, Wei; Liang, Xiaogan

2015-09-22

MoS2 and other semiconducting transition metal dichalcogenides (TMDCs) are of great interest due to their excellent physical properties and versatile chemistry. Although many recent research efforts have been directed to explore attractive properties associated with MoS2 monolayers, multilayer/few-layer MoS2 structures are indeed demanded by many practical scale-up device applications, because multilayer structures can provide sizable electronic/photonic state densities for driving upscalable electrical/optical signals. Currently there is a lack of processes capable of producing ordered, pristine multilayer structures of MoS2 (or other relevant TMDCs) with manufacturing-grade uniformity of thicknesses and electronic/photonic properties. In this article, we present a nanoimprint-based approach toward addressing this challenge. In this approach, termed as nanoimprint-assisted shear exfoliation (NASE), a prepatterned bulk MoS2 stamp is pressed into a polymeric fixing layer, and the imprinted MoS2 features are exfoliated along a shear direction. This shear exfoliation can significantly enhance the exfoliation efficiency and thickness uniformity of exfoliated flakes in comparison with previously reported exfoliation processes. Furthermore, we have preliminarily demonstrated the fabrication of multiple transistors and biosensors exhibiting excellent device-to-device performance consistency. Finally, we present a molecular dynamics modeling analysis of the scaling behavior of NASE. This work holds significant potential to leverage the superior properties of MoS2 and other emerging TMDCs for practical scale-up device applications.

MOF-Sensitized Solar Cells Enabled by a Pillared Porphyrin Framework

DOE PAGES

Spoerke, Erik D.; Small, Leo J.; Foster, Michael E.; ...

2017-03-01

Metal–organic frameworks (MOFs) are highly ordered, functionally tunable supramolecular materials with the potential to improve dye-sensitized solar cells (DSSCs). Several recent reports have indicated that photocurrent can be generated in Grätzel-type DSSC devices when MOFs are used as the sensitizer. However, the specific role(s) of the incorporated MOFs and the potential influence of residual MOF precursor species on device performance are unclear. Herein, we describe the assembly and characterization of a simplified DSSC platform in which isolated MOF crystals are used as the sensitizer in a planar device architecture. We selected a pillared porphyrin framework (PPF) as the MOF sensitizer,more » taking particular care to avoid contamination from light-absorbing MOF precursors. Photovoltaic and electrochemical characterization under simulated 1-sun and wavelength-selective illumination revealed photocurrent generation that is clearly ascribable to the PPF MOF. In conclusion, continued refinement of highly versatile MOF structure and chemistry holds promise for dramatic improvements in emerging photovoltaic technologies.« less

Modeling and Simulation of the Direct Methanol Fuel Cell

NASA Technical Reports Server (NTRS)

Wohr, M.; Narayanan, S. R.; Halpert, G.

1996-01-01

From intro.: The direct methanol liquid feed fuel cell uses aqueous solutions of methanol as fuel and oxygen or air as the oxidant and uses an ionically conducting polymer membrane such as Nafion(sup r)117 and the electrolyte. This type of direct oxidation cell is fuel versatile and offers significant advantages in terms of simplicity of design and operation...The present study focuses on the results of a phenomenological model based on current understanding of the various processed operating in these cells.

Study of Different Sol-Gel Coatings to Enhance the Lifetime of PDMS Devices: Evaluation of Their Biocompatibility

PubMed Central

Aymerich, María; Gómez-Varela, Ana I.; Álvarez, Ezequiel; Flores-Arias, María T.

2016-01-01

A study of PDMS (polydimethylsiloxane) sol-gel–coated channels fabricated using soft lithography and a laser direct writing technique is presented. PDMS is a biocompatible material that presents a high versatility to reproduce several structures. It is widely employed in the fabrication of preclinical devices due to its advantages but it presents a rapid chemical deterioration to organic solvents. The use of sol-gel layers to cover the PDMS overcomes this problem since it provides the robustness of glass for the structures made with PDMS, decreasing its deterioration and changing the biocompatibility of the surface. In this work, PDMS channels are coated with three different kinds of sol-gel compositions (60MTES/40TEOS, 70MTES/30TISP and 80MTES/20TISP). The endothelial cell adhesion to the different coated devices is evaluated in order to determine the most suitable sol-gel preparation conditions to enhance cellular adhesion. PMID:28773848

Rapid prototyping of multi-scale biomedical microdevices by combining additive manufacturing technologies.

PubMed

Hengsbach, Stefan; Lantada, Andrés Díaz

2014-08-01

The possibility of designing and manufacturing biomedical microdevices with multiple length-scale geometries can help to promote special interactions both with their environment and with surrounding biological systems. These interactions aim to enhance biocompatibility and overall performance by using biomimetic approaches. In this paper, we present a design and manufacturing procedure for obtaining multi-scale biomedical microsystems based on the combination of two additive manufacturing processes: a conventional laser writer to manufacture the overall device structure, and a direct-laser writer based on two-photon polymerization to yield finer details. The process excels for its versatility, accuracy and manufacturing speed and allows for the manufacture of microsystems and implants with overall sizes up to several millimeters and with details down to sub-micrometric structures. As an application example we have focused on manufacturing a biomedical microsystem to analyze the impact of microtextured surfaces on cell motility. This process yielded a relevant increase in precision and manufacturing speed when compared with more conventional rapid prototyping procedures.

First data with the Hybrid Array of Gamma Ray Detector (HAGRiD)

NASA Astrophysics Data System (ADS)

Smith, K.; Baugher, T.; Burcher, S.; Carter, A. B.; Cizewski, J. A.; Chipps, K. A.; Febbraro, M.; Grzywacz, R.; Jones, K. L.; Munoz, S.; Pain, S. D.; Paulauskas, S. V.; Ratkiewicz, A.; Schmitt, K. T.; Thornsberry, C.; Toomey, R.; Walter, D.; Willoughby, H.

2018-01-01

The structure of nuclei provides insight into astrophysical reaction rates that are difficult to measure directly. These studies are often performed with transfer reactions and β-decay measurements. These experiments benefit from particle-γ coincidence measurements which provide information beyond that of particle detection alone. The Hybrid Array of Gamma Ray Detectors (HAGRiD) of LaBr3(Ce) scintillators has been designed with this purpose in mind. The design of the array permits it to be coupled with particle detector systems, such as the Oak Ridge Rutgers University Barrel Array (ORRUBA) of silicon detectors and the Versatile Array of Neutron Detectors at Low Energy (VANDLE). It is also designed to operate with the Jet Experiments in Nuclear Structure and Astrophysics (JENSA) advanced target system. HAGRiD's design avoids compromising the charged-particle angular resolution due to compact geometries which are often used to increase the γ efficiency in other systems. First experiments with HAGRiD coupled to VANDLE as well as ORRUBA and JENSA are discussed.

Structural insights into the cofactor-assisted substrate recognition of yeast methylglyoxal/isovaleraldehyde reductase Gre2.

PubMed

Guo, Peng-Chao; Bao, Zhang-Zhi; Ma, Xiao-Xiao; Xia, Qingyou; Li, Wei-Fang

2014-09-01

Saccharomyces cerevisiae Gre2 (EC1.1.1.283) serves as a versatile enzyme that catalyzes the stereoselective reduction of a broad range of substrates including aliphatic and aromatic ketones, diketones, as well as aldehydes, using NADPH as the cofactor. Here we present the crystal structures of Gre2 from S. cerevisiae in an apo-form at 2.00Å and NADPH-complexed form at 2.40Å resolution. Gre2 forms a homodimer, each subunit of which contains an N-terminal Rossmann-fold domain and a variable C-terminal domain, which participates in substrate recognition. The induced fit upon binding to the cofactor NADPH makes the two domains shift toward each other, producing an interdomain cleft that better fits the substrate. Computational simulation combined with site-directed mutagenesis and enzymatic activity analysis enabled us to define a potential substrate-binding pocket that determines the stringent substrate stereoselectivity for catalysis. Copyright © 2014 Elsevier B.V. All rights reserved.

A new series of two-dimensional silicon crystals with versatile electronic properties

NASA Astrophysics Data System (ADS)

Chae, Kisung; Kim, Duck Young; Son, Young-Woo

2018-04-01

Silicon (Si) is one of the most extensively studied materials owing to its significance to semiconductor science and technology. While efforts to find a new three-dimensional (3D) Si crystal with unusual properties have made some progress, its two-dimensional (2D) phases have not yet been explored as much. Here, based on a newly developed systematic ab initio materials searching strategy, we report a series of novel 2D Si crystals with unprecedented structural and electronic properties. The new structures exhibit perfectly planar outermost surface layers of a distorted hexagonal network with their thicknesses varying with the atomic arrangement inside. Dramatic changes in electronic properties ranging from semimetal to semiconducting with indirect energy gaps and even to one with direct energy gaps are realized by varying thickness as well as by surface oxidation. Our predicted 2D Si crystals with flat surfaces and tunable electronic properties will shed light on the development of silicon-based 2D electronics technology.

Rapid shear alignment of sub-10 nm cylinder-forming block copolymer films based on thermal expansion mismatch

NASA Astrophysics Data System (ADS)

Nicaise, Samuel M.; Gadelrab, Karim R.; G, Amir Tavakkoli K.; Ross, Caroline A.; Alexander-Katz, Alfredo; Berggren, Karl K.

2018-01-01

Directed self-assembly of block copolymers (BCPs) provided by shear-stress can produce aligned sub-10 nm structures over large areas for applications in integrated circuits, next-generation data storage, and plasmonic structures. In this work, we present a fast, versatile BCP shear-alignment process based on coefficient of thermal expansion mismatch of the BCP film, a rigid top coat and a substrate. Monolayer and bilayer cylindrical microdomains of poly(styrene-b-dimethylsiloxane) aligned preferentially in-plane and orthogonal to naturally-forming or engineered cracks in the top coat film, allowing for orientation control over 1 cm2 substrates. Annealing temperatures, up to 275 °C, provided low-defect alignment up to 2 mm away from cracks for rapid (<1 min) annealing times. Finite-element simulations of the stress as a function of annealing time, annealing temperature, and distance from cracks showed that shear stress during the cooling phase of the thermal annealing was critical for the observed microdomain alignment.

Origami tubes assembled into stiff, yet reconfigurable structures and metamaterials.

PubMed

Filipov, Evgueni T; Tachi, Tomohiro; Paulino, Glaucio H

2015-10-06

Thin sheets have long been known to experience an increase in stiffness when they are bent, buckled, or assembled into smaller interlocking structures. We introduce a unique orientation for coupling rigidly foldable origami tubes in a "zipper" fashion that substantially increases the system stiffness and permits only one flexible deformation mode through which the structure can deploy. The flexible deployment of the tubular structures is permitted by localized bending of the origami along prescribed fold lines. All other deformation modes, such as global bending and twisting of the structural system, are substantially stiffer because the tubular assemblages are overconstrained and the thin sheets become engaged in tension and compression. The zipper-coupled tubes yield an unusually large eigenvalue bandgap that represents the unique difference in stiffness between deformation modes. Furthermore, we couple compatible origami tubes into a variety of cellular assemblages that can enhance mechanical characteristics and geometric versatility, leading to a potential design paradigm for structures and metamaterials that can be deployed, stiffened, and tuned. The enhanced mechanical properties, versatility, and adaptivity of these thin sheet systems can provide practical solutions of varying geometric scales in science and engineering.

Origami tubes assembled into stiff, yet reconfigurable structures and metamaterials

PubMed Central

Filipov, Evgueni T.; Tachi, Tomohiro; Paulino, Glaucio H.

2015-01-01

Thin sheets have long been known to experience an increase in stiffness when they are bent, buckled, or assembled into smaller interlocking structures. We introduce a unique orientation for coupling rigidly foldable origami tubes in a “zipper” fashion that substantially increases the system stiffness and permits only one flexible deformation mode through which the structure can deploy. The flexible deployment of the tubular structures is permitted by localized bending of the origami along prescribed fold lines. All other deformation modes, such as global bending and twisting of the structural system, are substantially stiffer because the tubular assemblages are overconstrained and the thin sheets become engaged in tension and compression. The zipper-coupled tubes yield an unusually large eigenvalue bandgap that represents the unique difference in stiffness between deformation modes. Furthermore, we couple compatible origami tubes into a variety of cellular assemblages that can enhance mechanical characteristics and geometric versatility, leading to a potential design paradigm for structures and metamaterials that can be deployed, stiffened, and tuned. The enhanced mechanical properties, versatility, and adaptivity of these thin sheet systems can provide practical solutions of varying geometric scales in science and engineering. PMID:26351693

Origami tubes assembled into stiff, yet reconfigurable structures and metamaterials

NASA Astrophysics Data System (ADS)

Filipov, Evgueni T.; Tachi, Tomohiro; Paulino, Glaucio H.

2015-10-01

Thin sheets have long been known to experience an increase in stiffness when they are bent, buckled, or assembled into smaller interlocking structures. We introduce a unique orientation for coupling rigidly foldable origami tubes in a "zipper" fashion that substantially increases the system stiffness and permits only one flexible deformation mode through which the structure can deploy. The flexible deployment of the tubular structures is permitted by localized bending of the origami along prescribed fold lines. All other deformation modes, such as global bending and twisting of the structural system, are substantially stiffer because the tubular assemblages are overconstrained and the thin sheets become engaged in tension and compression. The zipper-coupled tubes yield an unusually large eigenvalue bandgap that represents the unique difference in stiffness between deformation modes. Furthermore, we couple compatible origami tubes into a variety of cellular assemblages that can enhance mechanical characteristics and geometric versatility, leading to a potential design paradigm for structures and metamaterials that can be deployed, stiffened, and tuned. The enhanced mechanical properties, versatility, and adaptivity of these thin sheet systems can provide practical solutions of varying geometric scales in science and engineering.

Colloidal assembly directed by virtual magnetic moulds

NASA Astrophysics Data System (ADS)

Demirörs, Ahmet F.; Pillai, Pramod P.; Kowalczyk, Bartlomiej; Grzybowski, Bartosz A.

2013-11-01

Interest in assemblies of colloidal particles has long been motivated by their applications in photonics, electronics, sensors and microlenses. Existing assembly schemes can position colloids of one type relatively flexibly into a range of desired structures, but it remains challenging to produce multicomponent lattices, clusters with precisely controlled symmetries and three-dimensional assemblies. A few schemes can efficiently produce complex colloidal structures, but they require system-specific procedures. Here we show that magnetic field microgradients established in a paramagnetic fluid can serve as `virtual moulds' to act as templates for the assembly of large numbers (~108) of both non-magnetic and magnetic colloidal particles with micrometre precision and typical yields of 80 to 90 per cent. We illustrate the versatility of this approach by producing single-component and multicomponent colloidal arrays, complex three-dimensional structures and a variety of colloidal molecules from polymeric particles, silica particles and live bacteria and by showing that all of these structures can be made permanent. In addition, although our magnetic moulds currently resemble optical traps in that they are limited to the manipulation of micrometre-sized objects, they are massively parallel and can manipulate non-magnetic and magnetic objects simultaneously in two and three dimensions.

Ordering in bio-inorganic hybrid nanomaterials probed by in situ scanning transmission X-ray microscopy

DOE PAGES

Lee, Jonathan R. I.; Bagge-Hansen, Michael; Tunuguntla, Ramya; ...

2015-04-15

Here, phospholipid bilayer coated Si nanowires are one-dimensional (1D) composites that provide versatile bio-nanoelectronic functionality via incorporation of a wide variety of biomolecules into the phospholipid matrix. The physiochemical behaviour of the phospholipid bilayer is strongly dependent on its structure and, as a consequence, substantial modelling and experimental efforts have been directed at the structural characterization of supported bilayers and unsupported phospholipid vesicles; nonetheless, the experimental studies conducted to date have exclusively involved volume-averaged techniques, which do not allow for the assignment of spatially resolved structural variations that could critically impact the performance of the 1D phospholipid-Si NW composites. Inmore » this manuscript, we use scanning transmission X-ray microscopy (STXM) to probe bond orientation and bilayer thickness as a function of position with a spatial resolution of ~30 nm for Δ9-cis 1,2-dioleoyl-sn-glycero-3-phosphocholine layers prepared Si NWs. When coupled with small angle X-ray scattering measurements, the STXM data reveal structural motifs of the Si NWs that give rise to multi-bilayer formation and enable assignment of the orientation of specific bonds known to affect the order and rigidity of phospholipid bilayers.« less

The versatile nature of miR-9/9* in human cancer.

PubMed

Nowek, Katarzyna; Wiemer, Erik A C; Jongen-Lavrencic, Mojca

2018-04-17

miR-9 and miR-9 * (miR-9/9 * ) were first shown to be expressed in the nervous system and to function as versatile regulators of neurogenesis. The variable expression levels of miR-9/9 * in human cancer prompted researchers to investigate whether these small RNAs may also have an important role in the deregulation of physiological and biochemical networks in human disease. In this review, we present a comprehensive overview of the involvement of miR-9/9 * in various human malignancies focusing on their opposing roles in supporting or suppressing tumor development and metastasis. Importantly, it is shown that the capacity of miR-9/9 * to impact tumor formation is independent from their influence on the metastatic potential of tumor cells. Moreover, data suggest that miR-9/9 * may increase malignancy of one cancer cell population at the expense of another. The functional versatility of miR-9/9 * emphasizes the complexity of studying miRNA function and the importance to perform functional studies of both miRNA strands in a relevant cellular context. The possible application of miR-9/9 * as targets for miRNA-based therapies is discussed, emphasizing the need to obtain a better understanding of the functional properties of these miRNAs and to develop safe delivery methods to target specific cell populations.

The versatile nature of miR-9/9* in human cancer

PubMed Central

Nowek, Katarzyna; Wiemer, Erik A.C.; Jongen-Lavrencic, Mojca

2018-01-01

miR-9 and miR-9* (miR-9/9*) were first shown to be expressed in the nervous system and to function as versatile regulators of neurogenesis. The variable expression levels of miR-9/9* in human cancer prompted researchers to investigate whether these small RNAs may also have an important role in the deregulation of physiological and biochemical networks in human disease. In this review, we present a comprehensive overview of the involvement of miR-9/9* in various human malignancies focusing on their opposing roles in supporting or suppressing tumor development and metastasis. Importantly, it is shown that the capacity of miR-9/9* to impact tumor formation is independent from their influence on the metastatic potential of tumor cells. Moreover, data suggest that miR-9/9* may increase malignancy of one cancer cell population at the expense of another. The functional versatility of miR-9/9* emphasizes the complexity of studying miRNA function and the importance to perform functional studies of both miRNA strands in a relevant cellular context. The possible application of miR-9/9* as targets for miRNA-based therapies is discussed, emphasizing the need to obtain a better understanding of the functional properties of these miRNAs and to develop safe delivery methods to target specific cell populations. PMID:29755694

Advanced Gas Turbine (AGT)

NASA Technical Reports Server (NTRS)

1983-01-01

The development and progress of the Advanced Gas Turbine engine program is examined. An analysis of the role of ceramics in the design and major engine components is included. Projected fuel economy, emissions and performance standards, and versatility in fuel use are also discussed.

Grazing-incidence small-angle X-ray scattering (GISAXS) on small periodic targets using large beams

PubMed Central

Soltwisch, Victor; Probst, Jürgen; Scholze, Frank; Krumrey, Michael

2017-01-01

Grazing-incidence small-angle X-ray scattering (GISAXS) is often used as a versatile tool for the contactless and destruction-free investigation of nano­structured surfaces. However, due to the shallow incidence angles, the footprint of the X-ray beam is significantly elongated, limiting GISAXS to samples with typical target lengths of several millimetres. For many potential applications, the production of large target areas is impractical, and the targets are surrounded by structured areas. Because the beam footprint is larger than the targets, the surrounding structures contribute parasitic scattering, burying the target signal. In this paper, GISAXS measurements of isolated as well as surrounded grating targets in Si substrates with line lengths from 50 µm down to 4 µm are presented. For the isolated grating targets, the changes in the scattering patterns due to the reduced target length are explained. For the surrounded grating targets, the scattering signal of a 15 µm × 15 µm target grating structure is separated from the scattering signal of 100 µm × 100 µm nanostructured surroundings by producing the target with a different orientation with respect to the predominant direction of the surrounding structures. As virtually all litho­graphically produced nanostructures have a predominant direction, the described technique allows GISAXS to be applied in a range of applications, e.g. for characterization of metrology fields in the semiconductor industry, where up to now it has been considered impossible to use this method due to the large beam footprint. PMID:28875030

Grazing-incidence small-angle X-ray scattering (GISAXS) on small periodic targets using large beams.

PubMed

Pflüger, Mika; Soltwisch, Victor; Probst, Jürgen; Scholze, Frank; Krumrey, Michael

2017-07-01

Grazing-incidence small-angle X-ray scattering (GISAXS) is often used as a versatile tool for the contactless and destruction-free investigation of nano-structured surfaces. However, due to the shallow incidence angles, the footprint of the X-ray beam is significantly elongated, limiting GISAXS to samples with typical target lengths of several millimetres. For many potential applications, the production of large target areas is impractical, and the targets are surrounded by structured areas. Because the beam footprint is larger than the targets, the surrounding structures contribute parasitic scattering, burying the target signal. In this paper, GISAXS measurements of isolated as well as surrounded grating targets in Si substrates with line lengths from 50 µm down to 4 µm are presented. For the isolated grating targets, the changes in the scattering patterns due to the reduced target length are explained. For the surrounded grating targets, the scattering signal of a 15 µm × 15 µm target grating structure is separated from the scattering signal of 100 µm × 100 µm nanostructured surroundings by producing the target with a different orientation with respect to the predominant direction of the surrounding structures. As virtually all litho-graphically produced nanostructures have a predominant direction, the described technique allows GISAXS to be applied in a range of applications, e.g.  for characterization of metrology fields in the semiconductor industry, where up to now it has been considered impossible to use this method due to the large beam footprint.

Assembly of RNA nanostructures on supported lipid bilayers

PubMed Central

Dabkowska, Aleksandra P.; Michanek, Agnes; Jaeger, Luc; Rabe, Michael; Chworos, Arkadiusz; Höök, Fredrik; Nylander, Tommy; Sparr, Emma

2014-01-01

The assembly of nucleic acid nanostructures with controlled size and shape has large impact in the fields of nanotechnology, nanomedicine and synthetic biology. The directed arrangement of nanostructures at interfaces is important for many applications. In spite of this, the use of laterally mobile lipid bilayers to control RNA three-dimensional nanostructure formation on surfaces remains largely unexplored. Here, we direct the self-assembly of RNA building blocks into three-dimensional structures of RNA on fluid lipid bilayers composed of cationic 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) or mixtures of zwitterionic 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine (DOPC) and cationic sphingosine. We demonstrate the stepwise supramolecular assembly of discrete building blocks through specific and selective RNA-RNA interactions, based on results from quartz crystal microbalance with dissipation (QCM-D), ellipsometry, fluorescence recovery after photobleaching (FRAP) and total internal reflection fluorescence microscopy (TIRF) experiments. The assembly can be controlled to give a densely packed single layer of RNA polyhedrons at the fluid lipid bilayer surface. We show that assembly of the 3D structure can be modulated by sequence specific interactions, surface charge and changes in the salt composition and concentration. In addition, the tertiary structure of the RNA polyhedron can be controllably switched from an extended structure to one that is dense and compact. The versatile approach to building up three-dimensional structures of RNA does not require modification of the surface or the RNA molecules, and can be used as a bottom-up means of nanofabrication of functionalized bio-mimicking surfaces. PMID:25417592

Real-time and quantitative fluorescent live-cell imaging with quadruplex-specific red-edge probe (G4-REP).

PubMed

Yang, Sunny Y; Amor, Souheila; Laguerre, Aurélien; Wong, Judy M Y; Monchaud, David

2017-05-01

The development of quadruplex-directed molecular diagnostic and therapy rely on mechanistic insights gained at both cellular and tissue levels by fluorescence imaging. This technique is based on fluorescent reporters that label cellular DNA and RNA quadruplexes to spatiotemporally address their complex cell biology. The photophysical characteristics of quadruplex probes usually dictate the modality of cell imaging by governing the selection of the light source (lamp, LED, laser), the optical light filters and the detection modality. Here, we report the characterizations of prototype from a new generation of quadruplex dye termed G4-REP (for quadruplex-specific red-edge probe) that provides fluorescence responses regardless of the excitation wavelength and modality (owing to the versatility gained through the red-edge effect), thus allowing for diverse applications and most imaging facilities. This is demonstrated by cell images (and associated quantifications) collected through confocal and multiphoton microscopy as well as through real-time live-cell imaging system over extended period, monitoring both non-cancerous and cancerous human cell lines. Our results promote a new way of designing versatile, efficient and convenient quadruplex-reporting dyes for tracking these higher-order nucleic acid structures in living human cells. This article is part of a Special Issue entitled "G-quadruplex" Guest Editor: Dr. Concetta Giancola and Dr. Daniela Montesarchio. Copyright © 2016 Elsevier B.V. All rights reserved.

Collagen-Gold Nanoparticle Conjugates for Versatile Biosensing

PubMed Central

Unser, Sarah; Holcomb, Samuel; Cary, ReJeana; Sagle, Laura

2017-01-01

Integration of noble metal nanoparticles with proteins offers promising potential to create a wide variety of biosensors that possess both improved selectivity and versatility. The multitude of functionalities that proteins offer coupled with the unique optical properties of noble metal nanoparticles can allow for the realization of simple, colorimetric sensors for a significantly larger range of targets. Herein, we integrate the structural protein collagen with 10 nm gold nanoparticles to develop a protein-nanoparticle conjugate which possess the functionality of the protein with the desired colorimetric properties of the nanoparticles. Applying the many interactions that collagen undergoes in the extracellular matrix, we are able to selectively detect both glucose and heparin with the same collagen-nanoparticle conjugate. Glucose is directly detected through the cross-linking of the collagen fibrils, which brings the attached nanoparticles into closer proximity, leading to a red-shift in the LSPR frequency. Conversely, heparin is detected through a competition assay in which heparin-gold nanoparticles are added to solution and compete with heparin in the solution for the binding sites on the collagen fibrils. The collagen-nanoparticle conjugates are shown to detect both glucose and heparin in the physiological range. Lastly, glucose is selectively detected in 50% mouse serum with the collagen-nanoparticle devices possessing a linear range of 3–25 mM, which is also within the physiologically relevant range. PMID:28212282

Mesostructured Block Copolymer Nanoparticles: Versatile Templates for Hybrid Inorganic/Organic Nanostructures

PubMed Central

Connal, Luke A.; Lynd, Nathaniel A.; Robb, Maxwell J.; See, Kimberly A.; Jang, Se Gyu; Spruell, Jason M.

2012-01-01

We present a versatile strategy to prepare a range of nanostructured poly(styrene)-block-poly(2-vinyl pyridine) copolymer particles with tunable interior morphology and controlled size by a simple solvent exchange procedure. A key feature of this strategy is the use of functional block copolymers incorporating reactive pyridyl moieties which allow the absorption of metal salts and other inorganic precursors to be directed. Upon reduction of the metal salts, well-defined hybrid metal nanoparticle arrays could be prepared, while the use of oxide precursors followed by calcination permits the synthesis of silica and titania particles. In both cases, ordered morphologies templated by the original block copolymer domains were obtained. PMID:23335837

Three camelid VHH domains in complex with porcine pancreatic alpha-amylase. Inhibition and versatility of binding topology.

PubMed

Desmyter, Aline; Spinelli, Silvia; Payan, Francoise; Lauwereys, Marc; Wyns, Lode; Muyldermans, Serge; Cambillau, Christian

2002-06-28

Camelids produce functional antibodies devoid of light chains and CH1 domains. The antigen-binding fragment of such heavy chain antibodies is therefore comprised in one single domain, the camelid heavy chain antibody VH (VHH). Here we report on the structures of three dromedary VHH domains in complex with porcine pancreatic alpha-amylase. Two VHHs bound outside the catalytic site and did not inhibit or inhibited only partially the amylase activity. The third one, AMD9, interacted with the active site crevice and was a strong amylase inhibitor (K(i) = 10 nm). In contrast with complexes of other proteinaceous amylase inhibitors, amylase kept its native structure. The water-accessible surface areas of VHHs covered by amylase ranged between 850 and 1150 A(2), values similar to or even larger than those observed in the complexes between proteins and classical antibodies. These values could certainly be reached because a surprisingly high extent of framework residues are involved in the interactions of VHHs with amylase. The framework residues that participate in the antigen recognition represented 25-40% of the buried surface. The inhibitory interaction of AMD9 involved mainly its complementarity-determining region (CDR) 2 loop, whereas the CDR3 loop was small and certainly did not protrude as it does in cAb-Lys3, a VHH-inhibiting lysozyme. AMD9 inhibited amylase, although it was outside the direct reach of the catalytic residues; therefore it is to be expected that inhibiting VHHs might also be elicited against proteases. These results illustrate the versatility and efficiency of VHH domains as protein binders and enzyme inhibitors and are arguments in favor of their use as drugs against diabetes.

Aminoacyl-tRNA synthetases: versatile players in the changing theater of translation.

PubMed Central

Francklyn, Christopher; Perona, John J; Puetz, Joern; Hou, Ya-Ming

2002-01-01

Aminoacyl-tRNA synthetases attach amino acids to the 3' termini of cognate tRNAs to establish the specificity of protein synthesis. A recent Asilomar conference (California, January 13-18, 2002) discussed new research into the structure-function relationship of these crucial enzymes, as well as a multitude of novel functions, including participation in amino acid biosynthesis, cell cycle control, RNA splicing, and export of tRNAs from nucleus to cytoplasm in eukaryotic cells. Together with the discovery of their role in the cellular synthesis of proteins to incorporate selenocysteine and pyrrolysine, these diverse functions of aminoacyl-tRNA synthetases underscore the flexibility and adaptability of these ancient enzymes and stimulate the development of new concepts and methods for expanding the genetic code. PMID:12458790

Recent developments in Cope-type hydroamination reactions of hydroxylamine and hydrazine derivatives.

PubMed

Beauchemin, André M

2013-11-07

Cope-type hydroaminations are versatile for the direct amination of alkenes, alkynes and allenes using hydroxylamines and hydrazine derivatives. These reactions occur via a concerted, 5-membered cyclic transition state that is the microscopic reverse of the Cope elimination. This article focuses on recent developments, including intermolecular variants, directed reactions, and asymmetric variants using aldehydes as tethering catalysts, and their applications in target-oriented synthesis.

Consensus-phenotype integration of transcriptomic and metabolomic data implies a role for metabolism in the chemosensitivity of tumour cells.

PubMed

Cavill, Rachel; Kamburov, Atanas; Ellis, James K; Athersuch, Toby J; Blagrove, Marcus S C; Herwig, Ralf; Ebbels, Timothy M D; Keun, Hector C

2011-03-01

Using transcriptomic and metabolomic measurements from the NCI60 cell line panel, together with a novel approach to integration of molecular profile data, we show that the biochemical pathways associated with tumour cell chemosensitivity to platinum-based drugs are highly coincident, i.e. they describe a consensus phenotype. Direct integration of metabolome and transcriptome data at the point of pathway analysis improved the detection of consensus pathways by 76%, and revealed associations between platinum sensitivity and several metabolic pathways that were not visible from transcriptome analysis alone. These pathways included the TCA cycle and pyruvate metabolism, lipoprotein uptake and nucleotide synthesis by both salvage and de novo pathways. Extending the approach across a wide panel of chemotherapeutics, we confirmed the specificity of the metabolic pathway associations to platinum sensitivity. We conclude that metabolic phenotyping could play a role in predicting response to platinum chemotherapy and that consensus-phenotype integration of molecular profiling data is a powerful and versatile tool for both biomarker discovery and for exploring the complex relationships between biological pathways and drug response.

The plant i-AAA protease controls the turnover of an essential mitochondrial protein import component.

PubMed

Opalińska, Magdalena; Parys, Katarzyna; Murcha, Monika W; Jańska, Hanna

2018-01-29

Mitochondria are multifunctional organelles that play a central role in energy metabolism. Owing to the life-essential functions of these organelles, mitochondrial content, quality and dynamics are tightly controlled. Across the species, highly conserved ATP-dependent proteases prevent malfunction of mitochondria through versatile activities. This study focuses on a molecular function of the plant mitochondrial inner membrane-embedded AAA protease (denoted i -AAA) FTSH4, providing its first bona fide substrate. Here, we report that the abundance of the Tim17-2 protein, an essential component of the TIM17:23 translocase (Tim17-2 together with Tim50 and Tim23), is directly controlled by the proteolytic activity of FTSH4. Plants that are lacking functional FTSH4 protease are characterized by significantly enhanced capacity of preprotein import through the TIM17:23-dependent pathway. Taken together, with the observation that FTSH4 prevents accumulation of Tim17-2, our data point towards the role of this i -AAA protease in the regulation of mitochondrial biogenesis in plants. © 2018. Published by The Company of Biologists Ltd.

Functions of Replication Protein A as a Sensor of R Loops and a Regulator of RNaseH1

PubMed Central

Nguyen, Hai Dang; Yadav, Tribhuwan; Giri, Sumanprava; Saez, Borja; Graubert, Timothy A.; Zou, Lee

2017-01-01

R loop, a transcription intermediate containing RNA:DNA hybrids and displaced single-stranded DNA (ssDNA), has emerged as a major source of genomic instability. RNaseH1, which cleaves the RNA in RNA:DNA hybrids, plays an important role in R loop suppression. Here, we show that replication protein A (RPA), a ssDNA-binding protein, interacts with RNaseH1 and colocalizes with both RNaseH1 and R loops in cells. In vitro, purified RPA directly enhances the association of RNaseH1 with RNA:DNA hybrids and stimulates the activity of RNaseH1 on R loops. An RPA binding-defective RNaseH1 mutant is not efficiently stimulated by RPA in vitro, fails to accumulate at R loops in cells, and loses the ability to suppress R loops and associated genomic instability. Thus, in addition to sensing DNA damage and replication stress, RPA is a sensor of R loops and a regulator of RNaseH1, extending the versatile role of RPA in suppression of genomic instability. PMID:28257700

Environmental versatility promotes modularity in genome-scale metabolic networks.

PubMed

Samal, Areejit; Wagner, Andreas; Martin, Olivier C

2011-08-24

The ubiquity of modules in biological networks may result from an evolutionary benefit of a modular organization. For instance, modularity may increase the rate of adaptive evolution, because modules can be easily combined into new arrangements that may benefit their carrier. Conversely, modularity may emerge as a by-product of some trait. We here ask whether this last scenario may play a role in genome-scale metabolic networks that need to sustain life in one or more chemical environments. For such networks, we define a network module as a maximal set of reactions that are fully coupled, i.e., whose fluxes can only vary in fixed proportions. This definition overcomes limitations of purely graph based analyses of metabolism by exploiting the functional links between reactions. We call a metabolic network viable in a given chemical environment if it can synthesize all of an organism's biomass compounds from nutrients in this environment. An organism's metabolism is highly versatile if it can sustain life in many different chemical environments. We here ask whether versatility affects the modularity of metabolic networks. Using recently developed techniques to randomly sample large numbers of viable metabolic networks from a vast space of metabolic networks, we use flux balance analysis to study in silico metabolic networks that differ in their versatility. We find that highly versatile networks are also highly modular. They contain more modules and more reactions that are organized into modules. Most or all reactions in a module are associated with the same biochemical pathways. Modules that arise in highly versatile networks generally involve reactions that process nutrients or closely related chemicals. We also observe that the metabolism of E. coli is significantly more modular than even our most versatile networks. Our work shows that modularity in metabolic networks can be a by-product of functional constraints, e.g., the need to sustain life in multiple environments. This organizational principle is insensitive to the environments we consider and to the number of reactions in a metabolic network. Because we observe this principle not just in one or few biological networks, but in large random samples of networks, we propose that it may be a generic principle of metabolic network organization.

Current progress in Structure-Based Rational Drug Design marks a new mindset in drug discovery

PubMed Central

Lounnas, Valère; Ritschel, Tina; Kelder, Jan; McGuire, Ross; Bywater, Robert P.; Foloppe, Nicolas

2013-01-01

The past decade has witnessed a paradigm shift in preclinical drug discovery with structure-based drug design (SBDD) making a comeback while high-throughput screening (HTS) methods have continued to generate disappointing results. There is a deficit of information between identified hits and the many criteria that must be fulfilled in parallel to convert them into preclinical candidates that have a real chance to become a drug. This gap can be bridged by investigating the interactions between the ligands and their receptors. Accurate calculations of the free energy of binding are still elusive; however progresses were made with respect to how one may deal with the versatile role of water. A corpus of knowledge combining X-ray structures, bioinformatics and molecular modeling techniques now allows drug designers to routinely produce receptor homology models of increasing quality. These models serve as a basis to establish and validate efficient rationales used to tailor and/or screen virtual libraries with enhanced chances of obtaining hits. Many case reports of successful SBDD show how synergy can be gained from the combined use of several techniques. The role of SBDD with respect to two different classes of widely investigated pharmaceutical targets: (a) protein kinases (PK) and (b) G-protein coupled receptors (GPCR) is discussed. Throughout these examples prototypical situations covering the current possibilities and limitations of SBDD are presented. PMID:24688704

Controlled molecular self-assembly of complex three-dimensional structures in soft materials.

PubMed

Huang, Changjin; Quinn, David; Suresh, Subra; Hsia, K Jimmy

2018-01-02

Many applications in tissue engineering, flexible electronics, and soft robotics call for approaches that are capable of producing complex 3D architectures in soft materials. Here we present a method using molecular self-assembly to generate hydrogel-based 3D architectures that resembles the appealing features of the bottom-up process in morphogenesis of living tissues. Our strategy effectively utilizes the three essential components dictating living tissue morphogenesis to produce complex 3D architectures: modulation of local chemistry, material transport, and mechanics, which can be engineered by controlling the local distribution of polymerization inhibitor (i.e., oxygen), diffusion of monomers/cross-linkers through the porous structures of cross-linked polymer network, and mechanical constraints, respectively. We show that oxygen plays a role in hydrogel polymerization which is mechanistically similar to the role of growth factors in tissue growth, and the continued growth of hydrogel enabled by diffusion of monomers/cross-linkers into the porous hydrogel similar to the mechanisms of tissue growth enabled by material transport. The capability and versatility of our strategy are demonstrated through biomimetics of tissue morphogenesis for both plants and animals, and its application to generate other complex 3D architectures. Our technique opens avenues to studying many growth phenomena found in nature and generating complex 3D structures to benefit diverse applications. Copyright © 2017 the Author(s). Published by PNAS.

A general electrochemical method for label-free screening of protein–small molecule interactions†

PubMed Central

Cash, Kevin J.; Ricci, Francesco

2010-01-01

Here we report a versatile method by which the interaction between a protein and a small molecule, and the disruption of that interaction by competition with other small molecules, can be monitored electrochemically directly in complex sample matrices. PMID:19826675

Organosilicon platforms: bridging homogeneous, heterogeneous, and bioinspired catalysis

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

Kung, Mayfair C.; Riofski, Mark V.; Missaghi, Michael N.

2014-01-01

Organosilicon compounds form versatile structures such as cubic metallasiloxanes, cage-like silsesquioxanes, macromolecular nanocages, and flexible dendrimers and linear metallasiloxanes, and are useful as catalysts, ligands for metal complexes, and catalyst supports.

Isoforms, structures, and functions of versatile spectraplakin MACF1

PubMed Central

Hu, Lifang; Su, Peihong; Li, Runzhi; Yin, Chong; Zhang, Yan; Shang, Peng; Yang, Tuanmin; Qian, Airong

2016-01-01

Spectraplakins are crucially important communicators, linking cytoskeletal components to each other and cellular junctions. Microtubule actin crosslinking factor 1 (MACF1), also known as actin crosslinking family 7 (ACF7), is a member of the spectraplakin family. It is expressed in numerous tissues and cells as one extensively studied spectraplakin. MACF1 has several isoforms with unique structures and well-known function to be able to crosslink F-actin and microtubules. MACF1 is one versatile spectraplakin with various functions in cell processes, embryo development, tissue-specific functions, and human diseases. The importance of MACF1 has become more apparent in recent years. Here, we summarize the current knowledge on the presence and function of MACF1 and provide perspectives on future research of MACF1 based on our studies and others. [BMB Reports 2016; 49(1): 37-44] PMID:26521939

Small-Molecule Solar Cells with Simultaneously Enhanced Short-Circuit Current and Fill Factor to Achieve 11% Efficiency.

PubMed

Nian, Li; Gao, Ke; Jiang, Yufeng; Rong, Qikun; Hu, Xiaowen; Yuan, Dong; Liu, Feng; Peng, Xiaobin; Russell, Thomas P; Zhou, Guofu

2017-08-01

High-efficiency small-molecule-based organic photovoltaics (SM-OPVs) using two electron donors (p-DTS(FBTTh 2 ) 2 and ZnP) with distinctively different absorption and structural features are reported. Such a combination works well and synergically improves device short-circuit current density (J sc ) to 17.99 mA cm -2 and fill factor (FF) to 77.19%, yielding a milestone efficiency of 11%. To the best of our knowledge, this is the highest power conversion efficiency reported for SM-OPVs to date and the first time to combine high J sc over 17 mA cm -2 and high FF over 77% into one SM-OPV. The strategy of using multicomponent materials, with a selecting role of balancing varied electronic and structural necessities can be an important route to further developing higher performance devices. This development is important, which broadens the dimension and versatility of existing materials without much chemistry input. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Crystal engineering of versatile Hg(II) halides complexes of N,N,N‧,N‧-tetraalkyl substituted 3,5 pyridinedicarboxamides

NASA Astrophysics Data System (ADS)

Rana, Love Karan; Sharma, Sanyog; Hundal, Geeta

2018-02-01

Two new ligands N,N,N‧,N‧-tetraisopropyl/butyl-3,5-pyridinedicarboxamide (L3-L4) and six of their Hg(II)X2 complexes (where X = Cl-, Br- and I-), have been synthesized and characterized using single crystal X-ray diffraction and spectroscopic techniques. Complexes of L3 (1-3) with HgCl2/Br2/I2, have dimeric structure, with the ligand behaving as a 2-C linker. Complexes 4-6 are 1D coordination polymers with either 3- or 2-C, L4 linker and bridging halides. A delicate balance of anion, solvent, denticity and conformation of the ligands on the ensuing molecular and crystal structures has been delineated. Various non-covalent interactions, extending the dimensionality of the complexes are calculated, analyzed and discussed. A significant role of semi-localized LP···π non-covalent interactions in stabilizing the basic dimeric unit in the complexes, has been discerned.

Theory and simulation of DNA-coated colloids: a guide for rational design.

PubMed

Angioletti-Uberti, Stefano; Mognetti, Bortolo M; Frenkel, Daan

2016-03-07

By exploiting the exquisite selectivity of DNA hybridization, DNA-coated colloids (DNACCs) can be made to self-assemble in a wide variety of structures. The beauty of this system stems largely from its exceptional versatility and from the fact that a proper choice of the grafted DNA sequences yields fine control over the colloidal interactions. Theory and simulations have an important role to play in the optimal design of self assembling DNACCs. At present, the powerful model-based design tools are not widely used, because the theoretical literature is fragmented and the connection between different theories is often not evident. In this Perspective, we aim to discuss the similarities and differences between the different models that have been described in the literature, their underlying assumptions, their strengths and their weaknesses. Using the tools described in the present Review, it should be possible to move towards a more rational design of novel self-assembling structures of DNACCs and, more generally, of systems where ligand-receptor are used to control interactions.

Advances in molecular engineering of carbohydrate-binding modules.

PubMed

Armenta, Silvia; Moreno-Mendieta, Silvia; Sánchez-Cuapio, Zaira; Sánchez, Sergio; Rodríguez-Sanoja, Romina

2017-09-01

Carbohydrate-binding modules (CBMs) are non-catalytic domains that are generally appended to carbohydrate-active enzymes. CBMs have a broadly conserved structure that allows recognition of a notable variety of carbohydrates, in both their soluble and insoluble forms, as well as in their alpha and beta conformations and with different types of bonds or substitutions. This versatility suggests a high functional plasticity that is not yet clearly understood, in spite of the important number of studies relating protein structure and function. Several studies have explored the flexibility of these systems by changing or improving their specificity toward substrates of interest. In this review, we examine the molecular strategies used to identify CBMs with novel or improved characteristics. The impact of the spatial arrangement of the functional amino acids of CBMs is discussed in terms of unexpected new functions that are not related to the original biological roles of the enzymes. Proteins 2017; 85:1602-1617. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Structure and dynamics of cationic membrane peptides and proteins: Insights from solid-state NMR

PubMed Central

Hong, Mei; Su, Yongchao

2011-01-01

Many membrane peptides and protein domains contain functionally important cationic Arg and Lys residues, whose insertion into the hydrophobic interior of the lipid bilayer encounters significant energy barriers. To understand how these cationic molecules overcome the free energy barrier to insert into the lipid membrane, we have used solid-state NMR spectroscopy to determine the membrane-bound topology of these peptides. A versatile array of solid-state NMR experiments now readily yields the conformation, dynamics, orientation, depth of insertion, and site-specific protein–lipid interactions of these molecules. We summarize key findings of several Arg-rich membrane peptides, including β-sheet antimicrobial peptides, unstructured cell-penetrating peptides, and the voltage-sensing helix of voltage-gated potassium channels. Our results indicate the central role of guanidinium-phosphate and guanidinium-water interactions in dictating the structural topology of these cationic molecules in the lipid membrane, which in turn account for the mechanisms of this functionally diverse class of membrane peptides. PMID:21344534

Structural basis for spectrin recognition by ankyrin.

PubMed

Ipsaro, Jonathan J; Mondragón, Alfonso

2010-05-20

Maintenance of membrane integrity and organization in the metazoan cell is accomplished through intracellular tethering of membrane proteins to an extensive, flexible protein network. Spectrin, the principal component of this network, is anchored to membrane proteins through the adaptor protein ankyrin. To elucidate the atomic basis for this interaction, we determined a crystal structure of human betaI-spectrin repeats 13 to 15 in complex with the ZU5-ANK domain of human ankyrin R. The structure reveals the role of repeats 14 to 15 in binding, the electrostatic and hydrophobic contributions along the interface, and the necessity for a particular orientation of the spectrin repeats. Using structural and biochemical data as a guide, we characterized the individual proteins and their interactions by binding and thermal stability analyses. In addition to validating the structural model, these data provide insight into the nature of some mutations associated with cell morphology defects, including those found in human diseases such as hereditary spherocytosis and elliptocytosis. Finally, analysis of the ZU5 domain suggests it is a versatile protein-protein interaction module with distinct interaction surfaces. The structure represents not only the first of a spectrin fragment in complex with its binding partner, but also that of an intermolecular complex involving a ZU5 domain.

FRAGSTATS: spatial pattern analysis program for quantifying landscape structure.

Treesearch

Kevin McGarigal; Barbara J. Marks

1995-01-01

This report describes a program, FRAGSTATS, developed to quantify landscape structure. FRAGSTATS offers a comprehensive choice of landscape metrics and was designed to be as versatile as possible. The program is almost completely automated and thus requires little technical training. Two separate versions of FRAGSTATS exist: one for vector images and one for raster...

Membrane remodeling by amyloidogenic and non-amyloidogenic proteins studied by EPR.

PubMed

Varkey, Jobin; Langen, Ralf

2017-07-01

The advancement in site-directed spin labeling of proteins has enabled EPR studies to expand into newer research areas within the umbrella of protein-membrane interactions. Recently, membrane remodeling by amyloidogenic and non-amyloidogenic proteins has gained a substantial interest in relation to driving and controlling vital cellular processes such as endocytosis, exocytosis, shaping of organelles like endoplasmic reticulum, Golgi and mitochondria, intracellular vesicular trafficking, formation of filopedia and multivesicular bodies, mitochondrial fusion and fission, and synaptic vesicle fusion and recycling in neurotransmission. Misregulation in any of these processes due to an aberrant protein (mutation or misfolding) or alteration of lipid metabolism can be detrimental to the cell and cause disease. Dissection of the structural basis of membrane remodeling by proteins is thus quite necessary for an understanding of the underlying mechanisms, but it remains a formidable task due to the difficulties of various common biophysical tools in monitoring the dynamic process of membrane binding and bending by proteins. This is largely since membranes generally complicate protein structure analysis and this problem is amplified for structural analysis in the presence of different types of membrane curvatures. Recent EPR studies on membrane remodeling by proteins show that a significant structural information can be generated to delineate the role of different protein modules, domains and individual amino acids in the generation of membrane curvature. These studies also show how EPR can complement the data obtained by high resolution techniques such as X-ray and NMR. This perspective covers the application of EPR in recent studies for understanding membrane remodeling by amyloidogenic and non-amyloidogenic proteins that is useful for researchers interested in using or complimenting EPR to gain better understanding of membrane remodeling. We also discuss how a single protein can generate different type of membrane curvatures using specific conformations for specific membrane structures and how EPR is a versatile tool well-suited to analyze subtle alterations in structures under such modifying conditions which otherwise would have been difficult using other biophysical tools. Copyright © 2017 Elsevier Inc. All rights reserved.

EVENT-LEVEL ANALYSIS OF ANAL SEX ROLES AND SEX DRUG USE AMONG GAY AND BISEXUAL MEN IN VANCOUVER, BRITISH COLUMBIA, CANADA

PubMed Central

Rich, Ashleigh J; Lachowsky, Nathan J; Cui, Zishan; Sereda, Paul; Lal, Allan; Moore, David M; Hogg, Robert S; Roth, Eric A

2015-01-01

This study analyzed event-level partnership data from a computer-assisted survey of 719 gay and bisexual men (GBM) enrolled in the Momentum Health Study to delineate potential linkages between anal sex roles and so-called “sex drugs”, i.e. erectile dysfunction drugs (EDD), poppers and crystal methamphetamine. Univariable and multivariable analyses using generalized linear mixed models with logit link function with sexual encounters (n=2,514) as the unit of analysis tested four hypotheses: 1) EDD are significantly associated with insertive anal sex roles, 2) poppers are significantly associated with receptive anal sex, 3) both poppers and EDD are significantly associated with anal sexual versatility and, 4) crystal methamphetamine is significantly associated with all anal sex roles. Data for survey respondents and their sexual partners allowed testing these hypotheses for both anal sex partners in the same encounter. Multivariable results supported the first three hypotheses. Crystal methamphetamine was significantly associated with all anal sex roles in the univariable models, but not significant in any multivariable ones. Other multivariable significant variables included attending group sex events, venue where first met, and self-described sexual orientation. Results indicate that GBM sex-drug use behavior features rational decision-making strategies linked to anal sex roles. They also suggest that more research on anal sex roles, particularly versatility, is needed, and that sexual behavior research can benefit from partnership analysis. PMID:26525571

Event-Level Analysis of Anal Sex Roles and Sex Drug Use Among Gay and Bisexual Men in Vancouver, British Columbia, Canada.

PubMed

Rich, Ashleigh J; Lachowsky, Nathan J; Cui, Zishan; Sereda, Paul; Lal, Allan; Moore, David M; Hogg, Robert S; Roth, Eric A

2016-08-01

This study analyzed event-level partnership data from a computer-assisted survey of 719 gay and bisexual men (GBM) enrolled in the Momentum Health Study to delineate potential linkages between anal sex roles and the so-called "sex drugs," i.e., erectile dysfunction drugs (EDD), poppers, and crystal methamphetamine. Univariable and multivariable analyses using generalized linear mixed models with logit link function with sexual encounters (n = 2514) as the unit of analysis tested four hypotheses: (1) EDD are significantly associated with insertive anal sex roles, (2) poppers are significantly associated with receptive anal sex, (3) both poppers and EDD are significantly associated with anal sexual versatility, and (4) crystal methamphetamine is significantly associated with all anal sex roles. Data for survey respondents and their sexual partners allowed testing these hypotheses for both anal sex partners in the same encounter. Multivariable results supported the first three hypotheses. Crystal methamphetamine was significantly associated with all anal sex roles in the univariable models, but not significant in any multivariable ones. Other multivariable significant variables included attending group sex events, venue where first met, and self-described sexual orientation. Results indicate that GBM sex-drug use behavior features rational decision-making strategies linked to anal sex roles. They also suggest that more research on anal sex roles, particularly versatility, is needed, and that sexual behavior research can benefit from partnership analysis.

Versatility and Invariance in the Evolution of Homologous Heteromeric Interfaces

PubMed Central

Andreani, Jessica; Faure, Guilhem; Guerois, Raphaël

2012-01-01

Evolutionary pressures act on protein complex interfaces so that they preserve their complementarity. Nonetheless, the elementary interactions which compose the interface are highly versatile throughout evolution. Understanding and characterizing interface plasticity across evolution is a fundamental issue which could provide new insights into protein-protein interaction prediction. Using a database of 1,024 couples of close and remote heteromeric structural interologs, we studied protein-protein interactions from a structural and evolutionary point of view. We systematically and quantitatively analyzed the conservation of different types of interface contacts. Our study highlights astonishing plasticity regarding polar contacts at complex interfaces. It also reveals that up to a quarter of the residues switch out of the interface when comparing two homologous complexes. Despite such versatility, we identify two important interface descriptors which correlate with an increased conservation in the evolution of interfaces: apolar patches and contacts surrounding anchor residues. These observations hold true even when restricting the dataset to transiently formed complexes. We show that a combination of six features related either to sequence or to geometric properties of interfaces can be used to rank positions likely to share similar contacts between two interologs. Altogether, our analysis provides important tracks for extracting meaningful information from multiple sequence alignments of conserved binding partners and for discriminating near-native interfaces using evolutionary information. PMID:22952442

Handedness is a biomarker of variation in anal sex role behavior and Recalled Childhood Gender Nonconformity among gay men

PubMed Central

Swift-Gallant, Ashlyn; Coome, Lindsay A.; Monks, D. Ashley; VanderLaan, Doug P.

2017-01-01

Developmental theories of the biological basis of sexual orientation suggest that sexually differentiated psychological and behavioural traits should be linked with sexual orientation. Subgroups of gay men delineated by anal sex roles differ according to at least one such trait: gender expression. The present study assessed the hypothesis that handedness, a biologically determined sexually differentiated trait, corresponds to differences in subgroups of gay men based on anal sex role. Furthermore, it assessed whether handedness mediates the association between gender nonconformity and male sexual orientation. Straight and gay men (N = 333) completed the Edinburgh Inventory of Handedness and the Recalled Childhood Gender Nonconformity Scale. Gay men also completed measures of anal sex role preference. As in previous studies, gay men showed greater non-right-handedness and gender nonconformity than straight men. Also, among gay men, bottoms/versatiles (i.e., gay men who take a receptive anal sex role, or who take on both a receptive and insertive anal sex role) were more gender-nonconforming than tops (i.e., gay men who take an insertive anal sex role). In support of the hypothesis, bottoms/versatiles were more non-right-handed than tops and handedness mediated the male sexual orientation and anal sex role differences in Recalled Childhood Gender Nonconformity. Together, these findings suggest that developmental processes linked to handedness underpin variation among men in sexual orientation and gender nonconformity as well as variation among subgroups of gay men that are delineated by anal sex roles. PMID:28234947

Customization and design of directed self-assembly using hybrid prepatterns

NASA Astrophysics Data System (ADS)

Cheng, Joy; Doerk, Gregory S.; Rettner, Charles T.; Singh, Gurpreet; Tjio, Melia; Truong, Hoa; Arellano, Noel; Balakrishnan, Srinivasan; Brink, Markus; Tsai, Hsinyu; Liu, Chi-Chun; Guillorn, Michael; Sanders, Daniel P.

2015-03-01

Diminishing error tolerance renders the customization of patterns created through directed self-assembly (DSA) extremely challenging at tighter pitch. A self-aligned customization scheme can be achieved using a hybrid prepattern comprising both organic and inorganic regions that serves as a guiding prepattern to direct the self-assembly of the block copolymers as well as a cut mask pattern for the DSA arrays aligned to it. In this paper, chemoepitaxy-based self-aligned customization is demonstrated using two types of organic-inorganic prepatterns. CHEETAH prepattern for "CHemoepitaxy Etch Trim using a self-Aligned Hardmask" of preferential hydrogen silsesquioxane (HSQ, inorganic resist), non-preferential organic underlayer is fabricated using electron beam lithography. Customized trench or hole arrays can be achieved through co-transfer of DSA-formed arrays and CHEETAH prepattern. Herein, we also introduce a tone-reversed version called reverse-CHEETAH (or rCHEETAH) in which customized line segments can be achieved through co-transfer of DSA-formed arrays formed on a prepattern wherein the inorganic HSQ regions are nonpreferential and the organic regions are PMMA preferential. Examples of two-dimensional self-aligned customization including 25nm pitch fin structures and an 8-bar "IBM" illustrate the versatility of this customization scheme using rCHEETAH.

Assembly of Triblock Amphiphilic Peptides into One-Dimensional Aggregates and Network Formation.

PubMed

Ozgur, Beytullah; Sayar, Mehmet

2016-10-06

Peptide assembly plays a key role in both neurological diseases and development of novel biomaterials with well-defined nanostructures. Synthetic model peptides provide a unique platform to explore the role of intermolecular interactions in the assembly process. A triblock peptide architecture designed by the Hartgerink group is a versatile system which relies on Coulomb interactions, hydrogen bonding, and hydrophobicity to guide these peptides' assembly at three different length scales: β-sheets, double-wall ribbon-like aggregates, and finally a highly porous network structure which can support gels with ≤1% by weight peptide concentration. In this study, by using molecular dynamics simulations of a structure based implicit solvent coarse grained model, we analyzed this hierarchical assembly process. Parametrization of our CG model is based on multiple-state points from atomistic simulations, which enables this model to represent the conformational adaptability of the triblock peptide molecule based on the surrounding medium. Our results indicate that emergence of the double-wall β-sheet packing mechanism, proposed in light of the experimental evidence, strongly depends on the subtle balance of the intermolecular forces. We demonstrate that, even though backbone hydrogen bonding dominates the early nucleation stages, depending on the strength of the hydrophobic and Coulomb forces, alternative structures such as zero-dimensional aggregates with two β-sheets oriented orthogonally (which we refer to as a cross-packed structure) and β-sheets with misoriented hydrophobic side chains are also feasible. We discuss the implications of these competing structures for the three different length scales of assembly by systematically investigating the influence of density, counterion valency, and hydrophobicity.

Sensitivity of system stability to model structure

USGS Publications Warehouse

Hosack, G.R.; Li, H.W.; Rossignol, P.A.

2009-01-01

A community is stable, and resilient, if the levels of all community variables can return to the original steady state following a perturbation. The stability properties of a community depend on its structure, which is the network of direct effects (interactions) among the variables within the community. These direct effects form feedback cycles (loops) that determine community stability. Although feedback cycles have an intuitive interpretation, identifying how they form the feedback properties of a particular community can be intractable. Furthermore, determining the role that any specific direct effect plays in the stability of a system is even more daunting. Such information, however, would identify important direct effects for targeted experimental and management manipulation even in complex communities for which quantitative information is lacking. We therefore provide a method that determines the sensitivity of community stability to model structure, and identifies the relative role of particular direct effects, indirect effects, and feedback cycles in determining stability. Structural sensitivities summarize the degree to which each direct effect contributes to stabilizing feedback or destabilizing feedback or both. Structural sensitivities prove useful in identifying ecologically important feedback cycles within the community structure and for detecting direct effects that have strong, or weak, influences on community stability. The approach may guide the development of management intervention and research design. We demonstrate its value with two theoretical models and two empirical examples of different levels of complexity. ?? 2009 Elsevier B.V. All rights reserved.

An Undergraduate Experiment on Nuclear Lifetime Measurement Using the Doppler Effect

ERIC Educational Resources Information Center

Campbell, J. L.; And Others

1972-01-01

While designed for a senior undergraduate laboratory, the experiment illustrates the principles involved in the various Doppler techniques currently used in nuclear lifetime studies and demonstrates the versatility of the Ge(Li) detector in applications other than direct energy or intensity measurement. (Author/TS)

Space-Inspired Trailers Encourage Exploration on Earth

NASA Technical Reports Server (NTRS)

2013-01-01

Architect Garret Finney joined Johnson Space Center's Habitability Design Center to work on creating comfortable, efficiently designed crew quarters for the ISS. Drawing directly on that experience, Finney founded Houston-based Cricket and set about creating unique, versatile recreational trailers that incorporate space habitat principles and features.

Learning With Computers; Today and Tomorrow.

ERIC Educational Resources Information Center

Bork, Alfred

This paper describes the present practical use of computers in two large beginning physics courses at the University of California, Irvine; discusses the versatility and desirability of computers in the field of education; and projects the possible future directions of computer-based learning. The advantages and disadvantages of educational…

The crystal structures of the tri-functional Chloroflexus aurantiacus and bi-functional Rhodobacter sphaeroides malyl-CoA lyases and comparison with CitE-like superfamily enzymes and malate synthases.

PubMed

Zarzycki, Jan; Kerfeld, Cheryl A

2013-11-09

Malyl-CoA lyase (MCL) is a promiscuous carbon-carbon bond lyase that catalyzes the reversible cleavage of structurally related Coenzyme A (CoA) thioesters. This enzyme plays a crucial, multifunctional role in the 3-hydroxypropionate bi-cycle for autotrophic CO2 fixation in Chloroflexus aurantiacus. A second, phylogenetically distinct MCL from Rhodobacter sphaeroides is involved in the ethylmalonyl-CoA pathway for acetate assimilation. Both MCLs belong to the large superfamily of CitE-like enzymes, which includes the name-giving β-subunit of citrate lyase (CitE), malyl-CoA thioesterases and other enzymes of unknown physiological function. The CitE-like enzyme superfamily also bears sequence and structural resemblance to the malate synthases. All of these different enzymes share highly conserved catalytic residues, although they catalyze distinctly different reactions: C-C bond formation and cleavage, thioester hydrolysis, or both (the malate synthases). Here we report the first crystal structures of MCLs from two different phylogenetic subgroups in apo- and substrate-bound forms. Both the C. aurantiacus and the R. sphaeroides MCL contain elaborations on the canonical β8/α8 TIM barrel fold and form hexameric assemblies. Upon ligand binding, changes in the C-terminal domains of the MCLs result in closing of the active site, with the C-terminal domain of one monomer forming a lid over and contributing side chains to the active site of the adjacent monomer. The distinctive features of the two MCL subgroups were compared to known structures of other CitE-like superfamily enzymes and to malate synthases, providing insight into the structural subtleties that underlie the functional versatility of these enzymes. Although the C. aurantiacus and the R. sphaeroides MCLs have divergent primary structures (~37% identical), their tertiary and quaternary structures are very similar. It can be assumed that the C-C bond formation catalyzed by the MCLs occurs as proposed for malate synthases. However, a comparison of the two MCL structures with known malate synthases raised the question why the MCLs are not also able to hydrolyze CoA thioester bonds. Our results suggest the previously proposed reaction mechanism for malate synthases may be incomplete or not entirely correct. Further studies involving site-directed mutagenesis based on these structures may be required to solve this puzzling question.

The Role of Electrospinning in the Emerging Field of Nanomedicine

PubMed Central

Chew, SY; Wen, Y; Dzenis, Y; Leong, KW

2008-01-01

The fact that in vivo the extracellular matrix or substratum with which cells interact often includes topography at the nanoscale underscores the importance of investigating cell-substrate interactions and performing cell culture at the submicron scale. An important and exciting direction of research in nanomedicine would be to gain an understanding and exploit the cellular response to nanostructures. Electrospinning is a simple and versatile technique that can produce a macroporous scaffold comprising randomly oriented or aligned nanofibers. It can also accommodate the incorporation of drug delivery function into the fibrous scaffold. Endowed with both topographical and biochemical signals such electrospun nanofibrous scaffolds may provide an optimal microenvironment for the seeded cells. This review covers the analysis and control of the electrospinning process, and describes the types of electrospun fibers fabricated for biomedical applications such as drug delivery and tissue engineering. PMID:17168776

Magnetic alignment of block copolymer microdomains by intrinsic chain anisotropy

DOE PAGES

Rokhlenko, Yekaterina; Yager, Kevin G.; Gopinadhan, Manesh; ...

2015-12-18

We examine the role of intrinsic chain susceptibility anisotropy in magnetic field directed self-assembly of a block copolymer using in situ x-ray scattering. Alignment of a lamellar mesophase is observed on cooling across the disorder-order transition with the resulting orientational order inversely proportional to the cooling rate. We discuss the origin of the susceptibility anisotropy, Δ χ, that drives alignment and calculate its magnitude using coarse-grained molecular dynamics to sample conformations of surface-tethered chains, finding Δ χ ≈ 2×10 –8. From field-dependent scattering data, we estimate that grains of ≈ 1.2 μm are present during alignment. Furthermore, these results demonstratemore » that intrinsic anisotropy is sufficient to support strong field-induced mesophase alignment and suggest a versatile strategy for field control of orientational order in block copolymers.« less

Integrated Affinity Biosensing Platforms on Screen-Printed Electrodes Electrografted with Diazonium Salts

PubMed Central

Yáñez-Sedeño, Paloma

2018-01-01

Adequate selection of the electrode surface and the strategies for its modification to enable subsequent immobilization of biomolecules and/or nanomaterials integration play a major role in the performance of electrochemical affinity biosensors. Because of the simplicity, rapidity and versatility, electrografting using diazonium salt reduction is among the most currently used functionalization methods to provide the attachment of an organic layer to a conductive substrate. This particular chemistry has demonstrated to be a powerful tool to covalently immobilize in a stable and reproducible way a wide range of biomolecules or nanomaterials onto different electrode surfaces. Considering the great progress and interesting features arisen in the last years, this paper outlines the potential of diazonium chemistry to prepare single or multianalyte electrochemical affinity biosensors on screen-printed electrodes (SPEs) and points out the existing challenges and future directions in this field. PMID:29495294

Magnetic alignment of block copolymer microdomains by intrinsic chain anisotropy

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

Rokhlenko, Yekaterina; Yager, Kevin G.; Gopinadhan, Manesh

We examine the role of intrinsic chain susceptibility anisotropy in magnetic field directed self-assembly of a block copolymer using in situ x-ray scattering. Alignment of a lamellar mesophase is observed on cooling across the disorder-order transition with the resulting orientational order inversely proportional to the cooling rate. We discuss the origin of the susceptibility anisotropy, Δ χ, that drives alignment and calculate its magnitude using coarse-grained molecular dynamics to sample conformations of surface-tethered chains, finding Δ χ ≈ 2×10 –8. From field-dependent scattering data, we estimate that grains of ≈ 1.2 μm are present during alignment. Furthermore, these results demonstratemore » that intrinsic anisotropy is sufficient to support strong field-induced mesophase alignment and suggest a versatile strategy for field control of orientational order in block copolymers.« less

Integrated Affinity Biosensing Platforms on Screen-Printed Electrodes Electrografted with Diazonium Salts.

PubMed

Yáñez-Sedeño, Paloma; Campuzano, Susana; Pingarrón, José M

2018-02-24

Adequate selection of the electrode surface and the strategies for its modification to enable subsequent immobilization of biomolecules and/or nanomaterials integration play a major role in the performance of electrochemical affinity biosensors. Because of the simplicity, rapidity and versatility, electrografting using diazonium salt reduction is among the most currently used functionalization methods to provide the attachment of an organic layer to a conductive substrate. This particular chemistry has demonstrated to be a powerful tool to covalently immobilize in a stable and reproducible way a wide range of biomolecules or nanomaterials onto different electrode surfaces. Considering the great progress and interesting features arisen in the last years, this paper outlines the potential of diazonium chemistry to prepare single or multianalyte electrochemical affinity biosensors on screen-printed electrodes (SPEs) and points out the existing challenges and future directions in this field.

Rational Design of Charge-Transfer Interactions in Halogen-Bonded Co-crystals toward Versatile Solid-State Optoelectronics.

PubMed

Zhu, Weigang; Zheng, Renhui; Zhen, Yonggang; Yu, Zhenyi; Dong, Huanli; Fu, Hongbing; Shi, Qiang; Hu, Wenping

2015-09-02

Charge-transfer (CT) interactions between donor (D) and acceptor (A) groups, as well as CT exciton dynamics, play important roles in optoelectronic devices, such as organic solar cells, photodetectors, and light-emitting sources, which are not yet well understood. In this contribution, the self-assembly behavior, molecular stacking structure, CT interactions, density functional theory (DFT) calculations, and corresponding physicochemical properties of two similar halogen-bonded co-crystals are comprehensively investigated and compared, to construct an "assembly-structure-CT-property" relationship. Bpe-IFB wire-like crystals (where Bpe = 1,2-bis(4-pyridyl)ethylene and IFB = 1,3,5-trifluoro-2,4,6-triiodobenzene), packed in a segregated stacking form with CT ground and excited states, are measured to be quasi-one-dimensional (1D) semiconductors and show strong violet-blue photoluminescence (PL) from the lowest CT1 excitons (ΦPL = 26.1%), which can be confined and propagate oppositely along the 1D axial direction. In comparison, Bpe-F4DIB block-like crystals (F4DIB = 1,4-diiodotetrafluorobenzene), packed in a mixed stacking form without CT interactions, are determined to be insulators and exhibit unique white light emission and two-dimensional optical waveguide property. Surprisingly, it seems that the intrinsic spectroscopic states of Bpe and F4DIB do not change after co-crystallization, which is also confirmed by theoretical calculations, thus offering a new design principle for white light emitting materials. More importantly, we show that the CT interactions in co-crystals are related to their molecular packing and can be triggered or suppressed by crystal engineering, which eventually leads to distinct optoelectronic properties. These results help us to rationally control the CT interactions in organic D-A systems by tuning the molecular stacking, toward the development of a fantastic "optoelectronic world".

Systematic Identification and Evolutionary Analysis of Catalytically Versatile Cytochrome P450 Monooxygenase Families Enriched in Model Basidiomycete Fungi

PubMed Central

Syed, Khajamohiddin; Shale, Karabo; Pagadala, Nataraj Sekhar; Tuszynski, Jack

2014-01-01

Genome sequencing of basidiomycetes, a group of fungi capable of degrading/mineralizing plant material, revealed the presence of numerous cytochrome P450 monooxygenases (P450s) in their genomes, with some exceptions. Considering the large repertoire of P450s found in fungi, it is difficult to identify P450s that play an important role in fungal metabolism and the adaptation of fungi to diverse ecological niches. In this study, we followed Sir Charles Darwin’s theory of natural selection to identify such P450s in model basidiomycete fungi showing a preference for different types of plant components degradation. Any P450 family comprising a large number of member P450s compared to other P450 families indicates its natural selection over other P450 families by its important role in fungal physiology. Genome-wide comparative P450 analysis in the basidiomycete species, Phanerochaete chrysosporium, Phanerochaete carnosa, Agaricus bisporus, Postia placenta, Ganoderma sp. and Serpula lacrymans, revealed enrichment of 11 P450 families (out of 68 P450 families), CYP63, CYP512, CYP5035, CYP5037, CYP5136, CYP5141, CYP5144, CYP5146, CYP5150, CYP5348 and CYP5359. Phylogenetic analysis of the P450 family showed species-specific alignment of P450s across the P450 families with the exception of P450s of Phanerochaete chrysosporium and Phanerochaete carnosa, suggesting paralogous evolution of P450s in model basidiomycetes. P450 gene-structure analysis revealed high conservation in the size of exons and the location of introns. P450s with the same gene structure were found tandemly arranged in the genomes of selected fungi. This clearly suggests that extensive gene duplications, particularly tandem gene duplications, led to the enrichment of selective P450 families in basidiomycetes. Functional analysis and gene expression profiling data suggest that members of the P450 families are catalytically versatile and possibly involved in fungal colonization of plant material. To our knowledge, this is the first report on the identification and comparative-evolutionary analysis of P450 families enriched in model basidiomycetes. PMID:24466198

Direct Electron Transfer of Enzymes in a Biologically Assembled Conductive Nanomesh Enzyme Platform.

PubMed

Lee, Seung-Woo; Lee, Ki-Young; Song, Yong-Won; Choi, Won Kook; Chang, Joonyeon; Yi, Hyunjung

2016-02-24

Nondestructive assembly of a nanostructured enzyme platform is developed in combination of the specific biomolecular attraction and electrostatic coupling for highly efficient direct electron transfer (DET) of enzymes with unprecedented applicability and versatility. The biologically assembled conductive nanomesh enzyme platform enables DET-based flexible integrated biosensors and DET of eight different enzyme with various catalytic activities. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hierarchical Helical Order in the Twisted Growth of Plant Organs

NASA Astrophysics Data System (ADS)

Wada, Hirofumi

2012-09-01

The molecular and cellular basis of left-right asymmetry in plant morphogenesis is a fundamental issue in biology. A rapidly elongating root or hypocotyl of twisting mutants of Arabidopsis thaliana exhibits a helical growth with a handedness opposite to that of the underlying cortical microtubule arrays in epidermal cells. However, how such a hierarchical helical order emerges is currently unknown. We propose a model for investigating macroscopic chiral asymmetry in Arabidopsis mutants. Our elastic model suggests that the helical pattern observed is a direct consequence of the simultaneous presence of anisotropic growth and tilting of cortical microtubule arrays. We predict that the root helical pitch angle is a function of the microtubule helical angle and elastic moduli of the tissues. The proposed model is versatile and is potentially important for other biological systems ranging from protein fibrous structures to tree trunks.

Electrically tunable lens speeds up 3D orbital tracking

PubMed Central

Annibale, Paolo; Dvornikov, Alexander; Gratton, Enrico

2015-01-01

3D orbital particle tracking is a versatile and effective microscopy technique that allows following fast moving fluorescent objects within living cells and reconstructing complex 3D shapes using laser scanning microscopes. We demonstrated notable improvements in the range, speed and accuracy of 3D orbital particle tracking by replacing commonly used piezoelectric stages with Electrically Tunable Lens (ETL) that eliminates mechanical movement of objective lenses. This allowed tracking and reconstructing shape of structures extending 500 microns in the axial direction. Using the ETL, we tracked at high speed fluorescently labeled genomic loci within the nucleus of living cells with unprecedented temporal resolution of 8ms using a 1.42NA oil-immersion objective. The presented technology is cost effective and allows easy upgrade of scanning microscopes for fast 3D orbital tracking. PMID:26114037

Wedge sampling for computing clustering coefficients and triangle counts on large graphs

DOE PAGES

Seshadhri, C.; Pinar, Ali; Kolda, Tamara G.

2014-05-08

Graphs are used to model interactions in a variety of contexts, and there is a growing need to quickly assess the structure of such graphs. Some of the most useful graph metrics are based on triangles, such as those measuring social cohesion. Despite the importance of these triadic measures, algorithms to compute them can be extremely expensive. We discuss the method of wedge sampling. This versatile technique allows for the fast and accurate approximation of various types of clustering coefficients and triangle counts. Furthermore, these techniques are extensible to counting directed triangles in digraphs. Our methods come with provable andmore » practical time-approximation tradeoffs for all computations. We provide extensive results that show our methods are orders of magnitude faster than the state of the art, while providing nearly the accuracy of full enumeration.« less

Liquid chromatography-tandem mass spectrometry characterization of five new leucinostatins produced by Paecilomyces lilacinus CG-189.

PubMed

Martinez, Ana Flávia Canovas; Moraes, Luiz Alberto Beraldo

2015-03-01

The fungus Paecilomyces lilacinus produces leucinostatins—peptaibiotics that exert a range of biological activities including antimalarial, antiviral, antitumor and phytotoxicity. In this paper, we developed an analytical method employing LC-MS/MS in the precursor ion and product ion scan modes to elucidate five new leucinostatins. Direct Infusion (DI-MS) helped to identify the most abundant leucinostatins: F, D B2, S, A and K. MS/MS analysis using a triple quadrupole operating at different scan modes is a versatile tool to study natural products, especially peptaibiotics. Although DI-MS full-scan analysis is rapid and sensitive, it cannot distinguish between peptide isomers. On the other hand, LC-MS/MS operated in the precursor ion and product ion modes is time consuming, but allows identifying the structure of isomers or isobar in crude extracts.

Production of membrane proteins without cells or detergents.

PubMed

Rajesh, Sundaresan; Knowles, Timothy; Overduin, Michael

2011-04-30

The production of membrane proteins in cellular systems is besieged by several problems due to their hydrophobic nature which often causes misfolding, protein aggregation and cytotoxicity, resulting in poor yields of stable proteins. Cell-free expression has emerged as one of the most versatile alternatives for circumventing these obstacles by producing membrane proteins directly into designed hydrophobic environments. Efficient optimisation of expression and solubilisation conditions using a variety of detergents, membrane mimetics and lipids has yielded structurally and functionally intact membrane proteins, with yields several fold above the levels possible from cell-based systems. Here we review recently developed techniques available to produce functional membrane proteins, and discuss amphipols, nanodisc and styrene maleic acid lipid particle (SMALP) technologies that can be exploited alongside cell-free expression of membrane proteins. Copyright © 2010 Elsevier B.V. All rights reserved.

Reconfigurable antenna using plasma reflector

NASA Astrophysics Data System (ADS)

Jusoh, Mohd Taufik; Ahmad, Khairol Amali; Din, Muhammad Faiz Md; Hashim, Fakroul Ridzuan

2018-02-01

This paper presents the feasibility study and design of plasma implementation in industrial, scientific and medical (ISM) communication band. A reflector antenna with rounded shaped is proposed to collimate beam in particular direction radiated by a quarter wave antenna operating at 2.4GHz. The simulations result has shown that by using plasma as the reflector elements, the gain, directivity and radiation patterns are identical with metal elements with only small different in the broadside direction. The versatility of the antenna is achievable by introducing electrical reconfigurable option to change the beam pattern.

Investigation of the effects of melt electrospinning parameters on the direct-writing fiber size using orthogonal design

NASA Astrophysics Data System (ADS)

He, Feng-Li; He, Jin; Deng, Xudong; Li, Da-Wei; Ahmad, Fiaz; Liu, Yang-Yang; Liu, Ya-Li; Ye, Ya-Jing; Zhang, Chen-Yan; Yin, Da-Chuan

2017-10-01

Melt electrospinning is a complex process, and many of the processing parameters can impact the result of fiber formation. In this paper, we conducted a systematic investigation on the impacts of the melt electrospinning parameters (including temperature, needle gauge, flow rate and collector speed) on the fiber diameter via an orthogonal design experiment. The straight single fibers were fabricated using melt electrospinning in a direct-writing way with a diameter varied from 9.68  ±  0.93 µm to 48.55  ±  3.72 µm. The results showed that the fiber diameter changed differently against different parameters: when the temperature or needle gauge increased, the fiber diameter increased first and then decreased; when the flow rate increased, the fiber diameter decreased first and then increased; when the collector speed increased, the fiber diameter decreased monotonously. We also found that the collector speed was the most influential factor while the needle gauge was least important in determining the diameter of the fiber. Moreover, the feasibility of melt electrospinning in a direct-writing way as a novel 3D printing technology had been demonstrated by fabricating both uniform and controllable structures with high accuracy, based on the optimal parameters from the orthogonal experiments. The promising results indicated that melt electrospinning can be developed as a powerful technique for fabricating miniatured parts with high resolution and controllable structures for versatile potential applications.

An Interactive, Versatile, Three-Dimensional Display, Manipulation and Plotting System for Biomedical Research

ERIC Educational Resources Information Center

Feldmann, Richard J.; And Others

1972-01-01

Computer graphics provides a valuable tool for the representation and a better understanding of structures, both small and large. Accurate and rapid construction, manipulation, and plotting of structures, such as macromolecules as complex as hemoglobin, are performed by a collection of computer programs and a time-sharing computer. (21 references)…

The Relationship between Students' Leadership Style and Self-Directed Learning Level

ERIC Educational Resources Information Center

Strong, Robert; Wynn, J. Thomas; Irby, Travis L.; Lindner, James R.

2013-01-01

Leadership is a versatile process that requires working with others in personal and professional relationships to accomplish a goal. Cultivating leadership skills is important for students who are developing professional competencies. Leadership characteristics and abilities should be evaluated to assist in learning student traits to better…

Towards Understanding Plant Calcium Signaling through Calmodulin-Like Proteins: A Biochemical and Structural Perspective.

PubMed

La Verde, Valentina; Dominici, Paola; Astegno, Alessandra

2018-04-30

Ca 2+ ions play a key role in a wide variety of environmental responses and developmental processes in plants, and several protein families with Ca 2+ -binding domains have evolved to meet these needs, including calmodulin (CaM) and calmodulin-like proteins (CMLs). These proteins have no catalytic activity, but rather act as sensor relays that regulate downstream targets. While CaM is well-studied, CMLs remain poorly characterized at both the structural and functional levels, even if they are the largest class of Ca 2+ sensors in plants. The major structural theme in CMLs consists of EF-hands, and variations in these domains are predicted to significantly contribute to the functional versatility of CMLs. Herein, we focus on recent advances in understanding the features of CMLs from biochemical and structural points of view. The analysis of the metal binding and structural properties of CMLs can provide valuable insight into how such a vast array of CML proteins can coexist, with no apparent functional redundancy, and how these proteins contribute to cellular signaling while maintaining properties that are distinct from CaM and other Ca 2+ sensors. An overview of the principal techniques used to study the biochemical properties of these interesting Ca 2+ sensors is also presented.

Mesoscale assembly of chemically modified graphene into complex cellular networks

PubMed Central

Barg, Suelen; Perez, Felipe Macul; Ni, Na; do Vale Pereira, Paula; Maher, Robert C.; Garcia-Tuñon, Esther; Eslava, Salvador; Agnoli, Stefano; Mattevi, Cecilia; Saiz, Eduardo

2014-01-01

The widespread technological introduction of graphene beyond electronics rests on our ability to assemble this two-dimensional building block into three-dimensional structures for practical devices. To achieve this goal we need fabrication approaches that are able to provide an accurate control of chemistry and architecture from nano to macroscopic levels. Here, we describe a versatile technique to build ultralight (density ≥1 mg cm−3) cellular networks based on the use of soft templates and the controlled segregation of chemically modified graphene to liquid interfaces. These novel structures can be tuned for excellent conductivity; versatile mechanical response (elastic-brittle to elastomeric, reversible deformation, high energy absorption) and organic absorption capabilities (above 600 g per gram of material). The approach can be used to uncover the basic principles that will guide the design of practical devices that by combining unique mechanical and functional performance will generate new technological opportunities. PMID:24999766

An inorganic capping strategy for the seeded growth of versatile bimetallic nanostructures

DOE PAGES

Pei, Yuchen; Maligal-Ganesh, Raghu V.; Xiao, Chaoxian; ...

2015-09-11

Metal nanostructures have attracted great attention in various fields due to their tunable properties through precisely tailored sizes, compositions and structures. Using mesoporous silica (mSiO 2) as the inorganic capping agent and encapsulated Pt nanoparticles as the seeds, we developed a robust seeded growth method to prepare uniform bimetallic nanoparticles encapsulated in mesoporous silica shells (PtM@mSiO 2, M = Pd, Rh, Ni and Cu). Unexpectedly, we found that the inorganic silica shell is able to accommodate an eight-fold volume increase in the metallic core by reducing its thickness. The bimetallic nanoparticles encapsulated in mesoporous silica shells showed enhanced catalytic propertiesmore » and thermal stabilities compared with those prepared with organic capping agents. As a result, this inorganic capping strategy could find a broad application in the synthesis of versatile bimetallic nanostructures with exceptional structural control and enhanced catalytic properties.« less

Design of a dual sensor probe array for internal field measurement in Versatile Experiment Spherical Torusa)

NASA Astrophysics Data System (ADS)

Jeong-hun, Yang; Chung, Kyoung-Jae; An, YoungHwa; Jung, Bong Ki; Jo, Jong Gab; Hwang, Y. S.

2012-10-01

A dual sensor probe array is designed and constructed for internal magnetic field measurement at Versatile Experiment Spherical Torus (VEST) at the Seoul National University. Simultaneous use of Hall sensors and chip inductors allows cross-calibration among the measurements and compensation for each other's weaknesses while their small sizes are expected to cause only mild plasma perturbations. Calibration of the dual sensor probe array, using a Helmholtz coil, shows good sensitivity for the magnetic field measurement of the VEST. Prior to Ohmic start-up, the magnetic field structure inside the vacuum chamber is measured by using the calibrated probe array. The dual sensor probe array is expected to be useful in analyzing the temporal magnetic field structure change during the magnetic reconnection and in reconstruction of the current profile during the discharge of the VEST device.

Proton beam writing of long, arbitrary structures for micro/nano photonics and fluidics applications

NASA Astrophysics Data System (ADS)

Udalagama, Chammika; Teo, E. J.; Chan, S. F.; Kumar, V. S.; Bettiol, A. A.; Watt, F.

2011-10-01

The last decade has seen proton beam writing maturing into a versatile lithographic technique able to produce sub-100 nm, high aspect ratio structures with smooth side walls. However, many applications in the fields of photonics and fluidics require the fabrication of structures with high spatial resolution that extends over several centimetres. This cannot be achieved by purely magnetic or electrostatic beam scanning due to the large off-axis beam aberrations in high demagnification systems. As a result, this has limited us to producing long straight structures using a combination of beam and stage scanning. In this work we have: (1) developed an algorithm to include any arbitrary pattern into the writing process by using a more versatile combination of beam and stage scanning while (2) incorporating the use of the ubiquitous AutoCAD DXF (drawing exchange format) into the design process. We demonstrate the capability of this approach in fabricating structures such as Y-splitters, Mach-Zehnder modulators and microfluidic channels that are over several centimetres in length, in polymer. We also present optimisation of such parameters as scanning speed and scanning loops to improve on the surface roughness of the structures. This work opens up new possibilities of using CAD software in PBW for microphotonics and fluidics device fabrication.

Sex role segregation and mixing among men who have sex with men: implications for biomedical HIV prevention interventions.

PubMed

Armbruster, Benjamin; Roy, Sourya; Kapur, Abhinav; Schneider, John A

2013-01-01

Men who have sex with men (MSM) practice role segregation - insertive or receptive only sex positions instead of a versatile role - in several international settings where candidate biomedical HIV prevention interventions (e.g., circumcision, anal microbicide) will be tested. The effects of these position-specific interventions on HIV incidence are modeled. We developed a deterministic compartmental model to predict HIV incidence among Indian MSM using data from 2003-2010. The model's sex mixing matrix was derived from network data of Indian MSM (n=4604). Our model captures changing distribution of sex roles over time. We modeled microbicide and circumcision efficacy on trials with heterosexuals. Increasing numbers of versatile MSM resulted in little change in HIV incidence over 20 years. Anal microbicides and circumcision would decrease the HIV prevalence at 10 years from 15.6% to 12.9% and 12.7% respectively. Anal microbicides would provide similar protection to circumcision at the population level despite lower modeled efficacy (54% and 60% risk reduction, respectively). Combination of the interventions were additive: in 5 years, the reduction in HIV prevalence of the combination (-3.2%) is almost the sum of their individual reductions in HIV prevalence (-1.8% and -1.7%). MSM sex role segregation and mixing, unlike changes in the sex role distribution, may be important for evaluating HIV prevention interventions in international settings. Synergies between some position-specific prevention interventions such as circumcision and anal microbicides warrant further study.

Top, Bottom, and Versatile Anal Sex Roles in Same-Sex Male Relationships: Implications for Relationship and Sexual Satisfaction.

PubMed

Moskowitz, David A; Garcia, Christopher P

2018-06-01

Across much of the gay and bisexual male research on sexual position self-label (i.e., calling oneself a top, bottom, or versatile), there exist two commonalities: (1) studies tend to focus almost entirely on individual, relationally single androphilic men; (2) studies rarely account for relationships and relationship dynamics. In response, we explored the role of self-label over sexual and relationship satisfaction among gay and bisexual partnered men. Specifically, we looked at whether adopted sexual position identities were consonant or dissonant (i.e., matching or mismatching) with enacted behavior in relationships and how that impacted men's attitudes toward different relational attributes. Through an online survey, we sampled 169 men in same-sex relationships, asking them questions about their ideal penetrative role identities and their reality penetrative roles with their partner. We then asked them to rate their relationship on 10 sexual and interpersonal attributes. Multiple regression modeling suggested ideal-reality penetrative role dissonance was predictive of sexual dissatisfaction among tops who bottomed in their relationships and, to a lesser extent, bottoms who topped. In contrast, penetrative role dissonance was predictive of relationship satisfaction among tops who bottomed in their relationship, but not bottoms who topped. We conclude that a potential reason for this paradox among tops who bottom may be sexual altruism. That is, men may be satisfied with other aspects within their relationships, understand their partner's anal sex preferences, and accommodate that position in response to their initial relationship satisfaction.

Factors which motivate the use of social networks by students.

PubMed

González Sanmamed, Mercedes; Muñoz Carril, Pablo C; Dans Álvarez de Sotomayor, Isabel

2017-05-01

The aim of this research was to identify those factors which motivate the use of social networks by 4th year students in Secondary Education between the ages of 15 and 18. 1,144 students from 29 public and private schools took part. The data were analysed using Partial Least Squares Structural Equation Modelling technique. Versatility was confirmed to be the variable which most influences the motivation of students in their use of social networks. The positive relationship between versatility in the use of social networks and educational uses was also significant. The characteristics of social networks are analysed according to their versatility and how this aspect makes them attractive to students. The positive effects of social networks are discussed in terms of educational uses and their contribution to school learning. There is also a warning about the risks associated with misuse of social networks, and finally, the characteristics and conditions for the development of good educational practice through social networks are identified.

Matrix metalloproteinases in the brain and blood–brain barrier: Versatile breakers and makers

PubMed Central

Rempe, Ralf G; Hartz, Anika MS

2016-01-01

Matrix metalloproteinases are versatile endopeptidases with many different functions in the body in health and disease. In the brain, matrix metalloproteinases are critical for tissue formation, neuronal network remodeling, and blood–brain barrier integrity. Many reviews have been published on matrix metalloproteinases before, most of which focus on the two best studied matrix metalloproteinases, the gelatinases MMP-2 and MMP-9, and their role in one or two diseases. In this review, we provide a broad overview of the role various matrix metalloproteinases play in brain disorders. We summarize and review current knowledge and understanding of matrix metalloproteinases in the brain and at the blood–brain barrier in neuroinflammation, multiple sclerosis, cerebral aneurysms, stroke, epilepsy, Alzheimer’s disease, Parkinson’s disease, and brain cancer. We discuss the detrimental effects matrix metalloproteinases can have in these conditions, contributing to blood–brain barrier leakage, neuroinflammation, neurotoxicity, demyelination, tumor angiogenesis, and cancer metastasis. We also discuss the beneficial role matrix metalloproteinases can play in neuroprotection and anti-inflammation. Finally, we address matrix metalloproteinases as potential therapeutic targets. Together, in this comprehensive review, we summarize current understanding and knowledge of matrix metalloproteinases in the brain and at the blood–brain barrier in brain disorders. PMID:27323783

Xenobiotic Metabolism and Gut Microbiomes

PubMed Central

Das, Anubhav; Srinivasan, Meenakshi; Ghosh, Tarini Shankar; Mande, Sharmila S.

2016-01-01

Humans are exposed to numerous xenobiotics, a majority of which are in the form of pharmaceuticals. Apart from human enzymes, recent studies have indicated the role of the gut bacterial community (microbiome) in metabolizing xenobiotics. However, little is known about the contribution of the plethora of gut microbiome in xenobiotic metabolism. The present study reports the results of analyses on xenobiotic metabolizing enzymes in various human gut microbiomes. A total of 397 available gut metagenomes from individuals of varying age groups from 8 nationalities were analyzed. Based on the diversities and abundances of the xenobiotic metabolizing enzymes, various bacterial taxa were classified into three groups, namely, least versatile, intermediately versatile and highly versatile xenobiotic metabolizers. Most interestingly, specific relationships were observed between the overall drug consumption profile and the abundance and diversity of the xenobiotic metabolizing repertoire in various geographies. The obtained differential abundance patterns of xenobiotic metabolizing enzymes and bacterial genera harboring them, suggest their links to pharmacokinetic variations among individuals. Additional analyses of a few well studied classes of drug modifying enzymes (DMEs) also indicate geographic as well as age specific trends. PMID:27695034

Versatile aggressive mimicry of cicadas by an Australian predatory katydid.

PubMed

Marshall, David C; Hill, Kathy B R

2009-01-01

In aggressive mimicry, a predator or parasite imitates a signal of another species in order to exploit the recipient of the signal. Some of the most remarkable examples of aggressive mimicry involve exploitation of a complex signal-response system by an unrelated predator species. We have found that predatory Chlorobalius leucoviridis katydids (Orthoptera: Tettigoniidae) can attract male cicadas (Hemiptera: Cicadidae) by imitating the species-specific wing-flick replies of sexually receptive female cicadas. This aggressive mimicry is accomplished both acoustically, with tegminal clicks, and visually, with synchronized body jerks. Remarkably, the katydids respond effectively to a variety of complex, species-specific Cicadettini songs, including songs of many cicada species that the predator has never encountered. We propose that the versatility of aggressive mimicry in C. leucoviridis is accomplished by exploiting general design elements common to the songs of many acoustically signaling insects that use duets in pair-formation. Consideration of the mechanism of versatile mimicry in C. leucoviridis may illuminate processes driving the evolution of insect acoustic signals, which play a central role in reproductive isolation of populations and the formation of species.

Molecular Basis of Chemokine CXCL5-Glycosaminoglycan Interactions*

PubMed Central

2016-01-01

Chemokines, a large family of highly versatile small soluble proteins, play crucial roles in defining innate and adaptive immune responses by regulating the trafficking of leukocytes, and also play a key role in various aspects of human physiology. Chemokines share the characteristic feature of reversibly existing as monomers and dimers, and their functional response is intimately coupled to interaction with glycosaminoglycans (GAGs). Currently, nothing is known regarding the structural basis or molecular mechanisms underlying CXCL5-GAG interactions. To address this missing knowledge, we characterized the interaction of a panel of heparin oligosaccharides to CXCL5 using solution NMR, isothermal titration calorimetry, and molecular dynamics simulations. NMR studies indicated that the dimer is the high-affinity GAG binding ligand and that lysine residues from the N-loop, 40s turn, β3 strand, and C-terminal helix mediate binding. Isothermal titration calorimetry indicated a stoichiometry of two oligosaccharides per CXCL5 dimer. NMR-based structural models reveal that these residues form a contiguous surface within a monomer and, interestingly, that the GAG-binding domain overlaps with the receptor-binding domain, indicating that a GAG-bound chemokine cannot activate the receptor. Molecular dynamics simulations indicate that the roles of the individual lysines are not equivalent and that helical lysines play a more prominent role in determining binding geometry and affinity. Further, binding interactions and GAG geometry in CXCL5 are novel and distinctly different compared with the related chemokines CXCL1 and CXCL8. We conclude that a finely tuned balance between the GAG-bound dimer and free soluble monomer regulates CXCL5-mediated receptor signaling and function. PMID:27471273

Extrusomes in ciliates: diversification, distribution, and phylogenetic implications.

PubMed

Rosati, Giovanna; Modeo, Letizia

2003-01-01

Exocytosis is, in all likelihood, an important communication method among microbes. Ciliates are highly differentiated and specialized micro-organisms for which versatile and/or sophisticated exocytotic organelles may represent important adaptive tools. Thus, in ciliates, we find a broad range of different extrusomes, i.e ejectable membrane-bound organelles. Structurally simple extrusomes, like mucocysts and cortical granules, are widespread in different taxa within the phylum. They play the roles in each case required for the ecological needs of the organisms. Then, we find a number of more elaborate extrusomes, whose distribution within the phylum is more limited, and in some way related to phylogenetic affinities. Herein we provide a survey of literature and our data on selected extrusomes in ciliates. Their morphology, distribution, and possible function are discussed. The possible phylogenetic implications of their diversity are considered.

Convenient synthesis of twin-Christmas tree-like PbWO4 microcrystals and their photocatalytic properties

NASA Astrophysics Data System (ADS)

Zhang, Jin; Peng, Li-Li; Tang, Ying; Wu, Huijie

2017-06-01

Novel twin-Christmas tree-like PbWO4 microcrystals have been prepared via a convenient aqueous solution route at room temperature under the assistance of β-cyclodextrin (β-CD). The product was characterized by XRD, EDX, SEM, TEM, UV-vis and PL and BET techniques. It was found that β-CD plays an important role in the forming of twin-Christmas tree-like PbWO4 microcrystals. A five-step growth mechanism was proposed to explain the formation of such twin-Christmas tree-like structures. The photocatalytic performance of PbWO4 microcrystals was evaluated by measuring the decomposition rate of methylene blue (MB) and malachite green (MG) solution under the UV irradiation, and the photocatalytic results indicated that as-prepared PbWO4 microcrystals exhibit good and versatile photocatalytic activity as well as excellent recyclability.

Assembly of RNA nanostructures on supported lipid bilayers

NASA Astrophysics Data System (ADS)

Dabkowska, Aleksandra P.; Michanek, Agnes; Jaeger, Luc; Rabe, Michael; Chworos, Arkadiusz; Höök, Fredrik; Nylander, Tommy; Sparr, Emma

2014-12-01

The assembly of nucleic acid nanostructures with controlled size and shape has large impact in the fields of nanotechnology, nanomedicine and synthetic biology. The directed arrangement of nano-structures at interfaces is important for many applications. In spite of this, the use of laterally mobile lipid bilayers to control RNA three-dimensional nanostructure formation on surfaces remains largely unexplored. Here, we direct the self-assembly of RNA building blocks into three-dimensional structures of RNA on fluid lipid bilayers composed of cationic 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) or mixtures of zwitterionic 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine (DOPC) and cationic sphingosine. We demonstrate the stepwise supramolecular assembly of discrete building blocks through specific and selective RNA-RNA interactions, based on results from quartz crystal microbalance with dissipation (QCM-D), ellipsometry, fluorescence recovery after photobleaching (FRAP) and total internal reflection fluorescence microscopy (TIRF) experiments. The assembly can be controlled to give a densely packed single layer of RNA polyhedrons at the fluid lipid bilayer surface. We show that assembly of the 3D structure can be modulated by sequence specific interactions, surface charge and changes in the salt composition and concentration. In addition, the tertiary structure of the RNA polyhedron can be controllably switched from an extended structure to one that is dense and compact. The versatile approach to building up three-dimensional structures of RNA does not require modification of the surface or the RNA molecules, and can be used as a bottom-up means of nanofabrication of functionalized bio-mimicking surfaces.The assembly of nucleic acid nanostructures with controlled size and shape has large impact in the fields of nanotechnology, nanomedicine and synthetic biology. The directed arrangement of nano-structures at interfaces is important for many applications. In spite of this, the use of laterally mobile lipid bilayers to control RNA three-dimensional nanostructure formation on surfaces remains largely unexplored. Here, we direct the self-assembly of RNA building blocks into three-dimensional structures of RNA on fluid lipid bilayers composed of cationic 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) or mixtures of zwitterionic 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine (DOPC) and cationic sphingosine. We demonstrate the stepwise supramolecular assembly of discrete building blocks through specific and selective RNA-RNA interactions, based on results from quartz crystal microbalance with dissipation (QCM-D), ellipsometry, fluorescence recovery after photobleaching (FRAP) and total internal reflection fluorescence microscopy (TIRF) experiments. The assembly can be controlled to give a densely packed single layer of RNA polyhedrons at the fluid lipid bilayer surface. We show that assembly of the 3D structure can be modulated by sequence specific interactions, surface charge and changes in the salt composition and concentration. In addition, the tertiary structure of the RNA polyhedron can be controllably switched from an extended structure to one that is dense and compact. The versatile approach to building up three-dimensional structures of RNA does not require modification of the surface or the RNA molecules, and can be used as a bottom-up means of nanofabrication of functionalized bio-mimicking surfaces. Electronic supplementary information (ESI) available: Table with sequences of tRNA units used in this study; schematic structures of the RNA polyhedron and its building blocks; gel electrophoresis characterization of the RNA polyhedron and squares; AFM characterization of RNA tectosquare; schematic structures of RNA-9 and RNA-10 and their association with lipid bilayers; QCM-D frequency and dissipation data (as function of time) for adsorption of RNA polyhedrons, RNA squares and RNA9-10 TIRF images of RNA with Gelstar after photobleaching with analysis; Correlation plot in change of shear viscosity for TS3 and TO3-4 models for the stoichiometry of TS; QCM-D dissipation data for the sequential experiment in Fig. 5a; QCM-D and for the assembly of building blocks at the bilayer scaffold at varying bulk concentrations; QCM-D of adsorption of TS3. See DOI: 10.1039/c4nr05968a

Honeycomb-like PLGA- b-PEG Structure Creation with T-Junction Microdroplets.

PubMed

Gultekinoglu, Merve; Jiang, Xinyue; Bayram, Cem; Ulubayram, Kezban; Edirisinghe, Mohan

2018-06-04

Amphiphilic block copolymers are widely used in science owing to their versatile properties. In this study, amphiphilic block copolymer poly(lactic- co-glycolic acid)- block-poly(ethylene glycol) (PLGA- b-PEG) was used to create microdroplets in a T-junction microfluidic device with a well-defined geometry. To compare interfacial characteristics of microdroplets, dichloromethane (DCM) and chloroform were used to prepare PLGA- b-PEG solution as an oil phase. In the T-junction device, water and oil phases were manipulated at variable flow rates from 50 to 300 μL/min by increments of 50 μL/min. Fabricated microdroplets were directly collected on a glass slide. After a drying period, porous two-dimensional and three-dimensional structures were obtained as honeycomb-like structure. Pore sizes were increased according to increased water/oil flow rate for both DCM and chloroform solutions. Also, it was shown that increasing polymer concentration decreased the pore size of honeycomb-like structures at a constant water/oil flow rate (50:50 μL/min). Additionally, PLGA- b-PEG nanoparticles were also obtained on the struts of honeycomb-like structures according to the water solubility, volatility, and viscosity properties of oil phases, by the aid of Marangoni flow. The resulting structures have a great potential to be used in biomedical applications, especially in drug delivery-related studies, with nanoparticle forming ability and cellular responses in different surface morphologies.

Rhombic-Shaped Nanostructures and Mechanical Properties of 2D DNA Origami Constructed with Different Crossover/Nick Designs.

PubMed

Ma, Zhipeng; Huang, Yunfei; Park, Seongsu; Kawai, Kentaro; Kim, Do-Nyun; Hirai, Yoshikazu; Tsuchiya, Toshiyuki; Yamada, Hirofumi; Tabata, Osamu

2018-01-01

DNA origami methods enable the fabrication of various nanostructures and nanodevices, but their effective use depends on an understanding of their structural and mechanical properties and the effects of basic structural features. Frequency-modulation atomic force microscopy is introduced to directly characterize, in aqueous solution, the crossover regions of sets of 2D DNA origami based on different crossover/nick designs. Rhombic-shaped nanostructures formed under the influence of flexible crossovers placed between DNA helices are observed in DNA origami incorporating crossovers every 3, 4, or 6 DNA turns. The bending rigidity of crossovers is determined to be only one-third of that of the DNA helix, based on interhelical electrostatic forces reported elsewhere, and the measured pitches of the 3-turn crossover design rhombic-shaped nanostructures undergoing negligible bending. To evaluate the robustness of their structural integrity, they are intentionally and simultaneously stressed using force-controlled atomic force microscopy. DNA crossovers are verified to have a stabilizing effect on the structural robustness, while the nicks have an opposite effect. The structural and mechanical properties of DNA origami and the effects of crossovers and nicks revealed in this paper can provide information essential for the design of versatile DNA origami structures that exhibit specified and desirable properties. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

β-Sheet Containment by Flanking Prolines: Molecular Dynamic Simulations of the Inhibition of β-Sheet Elongation by Proline Residues in Human Prion Protein

PubMed Central

Shamsir, Mohd S.; Dalby, Andrew R.

2007-01-01

Previous molecular dynamic simulations have reported elongation of the existing β-sheet in prion proteins. Detailed examination has shown that these elongations do not extend beyond the proline residues flanking these β-sheets. In addition, proline has also been suggested to possess a possible structural role in preserving protein interaction sites by preventing invasion of neighboring secondary structures. In this work, we have studied the possible structural role of the flanking proline residues by simulating mutant structures with alternate substitution of the proline residues with valine. Simulations showed a directional inhibition of elongation, with the elongation progressing in the direction of valine including evident inhibition of elongation by existing proline residues. This suggests that the flanking proline residues in prion proteins may have a containment role and would confine the β-sheet within a specific length. PMID:17172295

Representations in Problem Solving: A Case Study with Optimization Problems

ERIC Educational Resources Information Center

Villegas, Jose L.; Castro, Enrique; Gutierrez, Jose

2009-01-01

Introduction: Representations play an essential role in mathematical thinking. They favor the understanding of mathematical concepts and stimulate the development of flexible and versatile thinking in problem solving. Here our focus is on their use in optimization problems, a type of problem considered important in mathematics teaching and…

The Brain's Versatile Toolbox.

ERIC Educational Resources Information Center

Pinker, Steven

1997-01-01

Considers the role of evolution and natural selection in the functioning of the modern human brain. Natural selection equipped humans with a mental toolbox of intuitive theories about the world which were used to master rocks, tools, plants, animals, and one another. The same toolbox is used today to master the intellectual challenges of modern…

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.

The Multipurpose Black Hawk Utility Helicopter: Rotary-wing Versatility Required for U.S. Marine Corps Enhanced Company Operations

DTIC Science & Technology

2009-01-01

THE FOREGOING STATEMENT. QUOTATION FROM, ABSTRACTION FROM, OR REPRODUCTION OF ALL OR ANY PART OF THIS DOCVMENT IS PERMITTED PROVIDED PROPER...Capabilities and Limitations 7 AH-IW/Z Cobra’s Role in Support ofECO 8 CH-53E Super Stallion Capabilities and Limitations 9 CH-53E Super Stallion’s Role...of aircraft. Analysis of the roles and capabilities of the AH-IW Super Cobra, CH-53E Super Stallion , MV-22B Osprey, and the UH- IN Huey will identify

Luminescent molecular rods - transition-metal alkynyl complexes.

PubMed

Yam, Vivian Wing-Wah; Wong, Keith Man-Chung

2005-01-01

A number of transition-metal complexes have been reported to exhibit rich luminescence, usually originating from phosphorescence. Such luminescence properties of the triplet excited state with a large Stoke's shift, long lifetime, high luminescence quantum yield as well as lower excitation energy, are envisaged to serve as an ideal candidate in the area of potential applications for chemosensors, dye-sensitized solar cells, flat panel displays, optics, new materials and biological sciences. Organic alkynes (poly-ynes), with extended or conjugatedπ-systems and rigid structure with linear geometry, have become a significant research area due to their novel electronic and physical properties and their potential applications in nanotechnology. Owing to the presence of unsaturated sp-hybridized carbon atoms, the alkynyl unit can serve as a versatile building block in the construction of alkynyl transition-metal complexes, not only throughσ-bonding but also viaπ-bonding interactions. By incorporation of linear alkynyl groups into luminescent transition-metal complexes, the alkynyl moiety with goodσ-donor,π-donor andπ-acceptor abilities is envisaged to tune or perturb the emission behaviors, including emission energy (color), intensity and lifetime by its role as an auxiliary ligand as well as to govern the emission origin from its direct involvement. This review summarizes recent efforts on the synthesis of luminescent rod-like alkynyl complexes with different classes of transition metals and details the effects of the introduction of alkynyl groups on the luminescence properties of the complexes.

Canonical Transient Receptor Potential (TRPC) 1 Acts as a Negative Regulator for Vanilloid TRPV6-mediated Ca2+ Influx*

PubMed Central

Schindl, Rainer; Fritsch, Reinhard; Jardin, Isaac; Frischauf, Irene; Kahr, Heike; Muik, Martin; Riedl, Maria Christine; Groschner, Klaus; Romanin, Christoph

2012-01-01

TRP proteins mostly assemble to homomeric channels but can also heteromerize, preferentially within their subfamilies. The TRPC1 protein is the most versatile member and forms various TRPC channel combinations but also unique channels with the distantly related TRPP2 and TRPV4. We show here a novel cross-family interaction between TRPC1 and TRPV6, a Ca2+ selective member of the vanilloid TRP subfamily. TRPV6 exhibited substantial co-localization and in vivo interaction with TRPC1 in HEK293 cells, however, no interaction was observed with TRPC3, TRPC4, or TRPC5. Ca2+ and Na+ currents of TRPV6-overexpressing HEK293 cells are significantly reduced by co-expression of TRPC1, correlating with a dramatically suppressed plasma membrane targeting of TRPV6. In line with their intracellular retention, remaining currents of TRPC1 and TRPV6 co-expression resemble in current-voltage relationship that of TRPV6. Studying the N-terminal ankyrin like repeat domain, structurally similar in the two proteins, we have found that these cytosolic segments were sufficient to mediate a direct heteromeric interaction. Moreover, the inhibitory role of TRPC1 on TRPV6 influx was also maintained by expression of only its N-terminal ankyrin-like repeat domain. Our experiments provide evidence for a functional interaction of TRPC1 with TRPV6 that negatively regulates Ca2+ influx in HEK293 cells. PMID:22932896

Heterologous expression of Homo sapiens alpha-folate receptors in E. coli by fusion with a trigger factor for enhanced solubilization.

PubMed

Miranda, Beatriz Nogueira Messias; Fotoran, Wesley Luzetti; Canduri, Fernanda; Souza, Dulce Helena Ferreira; Wunderlich, Gerhard; Carrilho, Emanuel

2018-02-01

The role of Alpha folate receptors (FRα) in folate metabolism and cancer development has been extensively studied. The reason for this is not only associated to its direct relation to disease development but also to its potential use as a highly sensitive and specific biomarker for cancers therapies. Over the recent years, the crystal structures of human FRα complexed with different ligands were described relying on an expensive and time-consuming production process. Here, we constructed an efficient system for the expression and purification of a human FRα in E. coli. Unlike a conventional expression method we used a specific protein fusion expressing the target protein together with a trigger factor (TF). This factor is a chaperone from E. coli that assists the correct folding of newly synthesized polypeptide chains. The activity of rTFFRα was comparable to glycosylphosphatidylinositol (GPI) anchored proteins extracted from HeLa tumor cells. Our work demonstrates a straightforward and versatile approach for the production of active human FRα by heterologous expression; this approach further enhances the development of inhibition studies and biotechnological applications. The purified product was then conjugated to liposomes, obtaining a 35% higher signal from densitometry measurement on the immunoblotting assay in the contruct containing the Ni-NTA tag, as a mimesis of an exosome, which is of vital importance to nanotherapeutic techniques associated to treatment and diagnosis of tumors. Copyright © 2017 Elsevier Inc. All rights reserved.

DEEM, a versatile platform of FRD measurement for highly multiplexed fibre systems in astronomy

NASA Astrophysics Data System (ADS)

Yan, Yunxiang; Yan, Qi; Wang, Gang; Sun, Weimin; Luo, A.-Li; Ma, Zhenyu; Zhang, Qiong; Li, Jian; Wang, Shuqing

2018-06-01

We present a new method of DEEM, the direct energy encircling method, for characterizing the performance of fibres in most astronomical spectroscopic applications. It is a versatile platform to measure focal ratio degradation (FRD), throughput, and point spread function. The principle of DEEM and the relation between the encircled energy and the spot size were derived and simulated based on the power distribution model (PDM). We analysed the errors of DEEM and pointed out the major error source for better understanding and optimization. The validation of DEEM has been confirmed by comparing the results with conventional method which shows that DEEM has good robustness with high accuracy in both stable and complex experiment environments. Applications on the integral field unit (IFU) show that the FRD of 50 μm core fibre is substandard for the requirement which requires the output focal ratio to be slower than 4.5. The homogeneity of throughput is acceptable and higher than 85 per cent. The prototype IFU of the first generation helps to find out the imperfections to optimize the new design of the next generation based on the staggered structure with 35 μm core fibres of N.A. = 0.12, which can improve the FRD performance. The FRD dependence on wavelength and core size is revealed that higher output focal ratio occurs at shorter wavelengths for large core fibres, which is in agreement with the prediction of PDM. But the dependence of the observed data is weaker than the prediction.

RNA Framework: an all-in-one toolkit for the analysis of RNA structures and post-transcriptional modifications.

PubMed

Incarnato, Danny; Morandi, Edoardo; Simon, Lisa Marie; Oliviero, Salvatore

2018-06-09

RNA is emerging as a key regulator of a plethora of biological processes. While its study has remained elusive for decades, the recent advent of high-throughput sequencing technologies provided the unique opportunity to develop novel techniques for the study of RNA structure and post-transcriptional modifications. Nonetheless, most of the required downstream bioinformatics analyses steps are not easily reproducible, thus making the application of these techniques a prerogative of few laboratories. Here we introduce RNA Framework, an all-in-one toolkit for the analysis of most NGS-based RNA structure probing and post-transcriptional modification mapping experiments. To prove the extreme versatility of RNA Framework, we applied it to both an in-house generated DMS-MaPseq dataset, and to a series of literature available experiments. Notably, when starting from publicly available datasets, our software easily allows replicating authors' findings. Collectively, RNA Framework provides the most complete and versatile toolkit to date for a rapid and streamlined analysis of the RNA epistructurome. RNA Framework is available for download at: http://www.rnaframework.com.

A Versatile, User-Oriented, Computerized Library System.

ERIC Educational Resources Information Center

Neuron, Eric

This paper deals with the problem of the referencing or storing methods in information systems which must be designed to allow for rapid retrieval of the key data leading to the desired information or the recovery of the information directly. Considered as a secondary, but frequently desirable, feature for the system is the ability to determine…

Using Specific Binding DNA Capture Elements to Direct Pulsed Power Killing of Biological Agents

DTIC Science & Technology

2003-06-01

Department of the Air Force position, policy, or decision unless so designated by other documentation. VI. REFERENCES [1] V. Majidi and M. R. Joseph...Spectroscopic applications of laser-induced plasmas,” Crit. Rev. Analyt. Chem. 23, 143-162, 1992. [2] V. Majidi , “Laser-induced plasmas: A versatile tool

A micromotor based on polymer single crystals and nanoparticles: toward functional versatility.

PubMed

Liu, Mei; Liu, Limei; Gao, Wenlong; Su, Miaoda; Ge, Ya; Shi, Lili; Zhang, Hui; Dong, Bin; Li, Christopher Y

2014-08-07

We report a multifunctional micromotor fabricated by the self-assembly technique using multifunctional materials, i.e. polymer single crystals and nanoparticles, as basic building blocks. Not only can this micromotor achieve autonomous and directed movement, it also possesses unprecedented functions, including enzymatic degradation-induced micromotor disassembly, sustained release and molecular detection.

Overcoming Microsoft Excel's Weaknesses for Crop Model Building and Simulations

ERIC Educational Resources Information Center

Sung, Christopher Teh Boon

2011-01-01

Using spreadsheets such as Microsoft Excel for building crop models and running simulations can be beneficial. Excel is easy to use, powerful, and versatile, and it requires the least proficiency in computer programming compared to other programming platforms. Excel, however, has several weaknesses: it does not directly support loops for iterative…

Luneburg lens in silicon photonics.

PubMed

Di Falco, Andrea; Kehr, Susanne C; Leonhardt, Ulf

2011-03-14

The Luneburg lens is an aberration-free lens that focuses light from all directions equally well. We fabricated and tested a Luneburg lens in silicon photonics. Such fully-integrated lenses may become the building blocks of compact Fourier optics on chips. Furthermore, our fabrication technique is sufficiently versatile for making perfect imaging devices on silicon platforms.

Analytical formulation of directly modulated OOFDM signals transmitted over an IM/DD dispersive link.

PubMed

Sánchez, C; Ortega, B; Wei, J L; Tang, J; Capmany, J

2013-03-25

We provide an analytical study on the propagation effects of a directly modulated OOFDM signal through a dispersive fiber and subsequent photo-detection. The analysis includes the effects of the laser operation point and the interplay between chromatic dispersion and laser chirp. The final expression allows to understand the physics behind the transmission of a multi-carrier signal in the presence of residual frequency modulation and the description of the induced intermodulation distortion gives us a detailed insight into the diferent intermodulation products which impair the recovered signal at the receiver-end side. Numerical comparisons between transmission simulations results and those provided by evaluating the expression obtained are carried out for different laser operation points. Results obtained by changing the fiber length, laser parameters and using single mode fiber with negative and positive dispersion are calculated in order to demonstrate the validity and versatility of the theory provided in this paper. Therefore, a novel analytical formulation is presented as a versatile tool for the description and study of IM/DD OOFDM systems with variable design parameters.

High resolution structure of cleaved Serpin 42 Da from Drosophila melanogaster.

PubMed

Ellisdon, Andrew M; Zhang, Qingwei; Henstridge, Michelle A; Johnson, Travis K; Warr, Coral G; Law, Ruby Hp; Whisstock, James C

2014-04-24

The Drosophila melanogaster Serpin 42 Da gene (previously Serpin 4) encodes a serine protease inhibitor that is capable of remarkable functional diversity through the alternative splicing of four different reactive centre loop exons. Eight protein isoforms of Serpin 42 Da have been identified to date, targeting the protease inhibitor to both different proteases and cellular locations. Biochemical and genetic studies suggest that Serpin 42 Da inhibits target proteases through the classical serpin 'suicide' inhibition mechanism, however the crystal structure of a representative Serpin 42 Da isoform remains to be determined. We report two high-resolution crystal structures of Serpin 42 Da representing the A/B isoforms in the cleaved conformation, belonging to two different space-groups and diffracting to 1.7 Å and 1.8 Å. Structural analysis reveals the archetypal serpin fold, with the major elements of secondary structure displaying significant homology to the vertebrate serpin, neuroserpin. Key residues known to have central roles in the serpin inhibitory mechanism are conserved in both the hinge and shutter regions of Serpin 42 Da. Furthermore, these structures identify important conserved interactions that appear to be of crucial importance in allowing the Serpin 42 Da fold to act as a versatile template for multiple reactive centre loops that have different sequences and protease specificities. In combination with previous biochemical and genetic studies, these structures confirm for the first time that the Serpin 42 Da isoforms are typical inhibitory serpin family members with the conserved serpin fold and inhibitory mechanism. Additionally, these data reveal the remarkable structural plasticity of serpins, whereby the basic fold is harnessed as a template for inhibition of a large spectrum of proteases by reactive centre loop exon 'switching'. This is the first structure of a Drosophila serpin reported to date, and will provide a platform for future mutational studies in Drosophila to ascertain the functional role of each of the Serpin 42 Da isoforms.

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

Dai, Sheng; Liu, Rui; Mahurin, Shannon Mark

A facile and versatile synthesis using dopamine as a carbon source gives hollow carbon spheres and yolk-shell Au{at}Carbon nanocomposites. The uniform nature of dopamine coatings and their high carbon yield endow the products with high structural integrity. The Au{at}C nanocomposites are catalytically active.

Phase transformation in tantalum under extreme laser deformation

DOE PAGES

Lu, C. -H.; Hahn, E. N.; Remington, B. A.; ...

2015-10-19

The structural and mechanical response of metals is intimately connected to phase transformations. For instance, the product of a phase transformation (martensite) is responsible for the extraordinary range of strength and toughness of steel, making it a versatile and important structural material. Although abundant in metals and alloys, the discovery of new phase transformations is not currently a common event and often requires a mix of experimentation, predictive computations, and luck. High-energy pulsed lasers enable the exploration of extreme pressures and temperatures, where such discoveries may lie. The formation of a hexagonal (omega) phase was observed in recovered monocrystalline body-centeredmore » cubic tantalum of four crystallographic orientations subjected to an extreme regime of pressure, temperature, and strain-rate. This was accomplished using high-energy pulsed lasers. The omega phase and twinning were identified by transmission electron microscopy at 70 GPa (determined by a corresponding VISAR experiment). It is proposed that the shear stresses generated by the uniaxial strain state of shock compression play an essential role in the transformation. In conclusion, molecular dynamics simulations show the transformation of small nodules from body-centered cubic to a hexagonal close-packed structure under the same stress state (pressure and shear).« less

Phase Transformation in Tantalum under Extreme Laser Deformation

PubMed Central

Lu, C.-H.; Hahn, E. N.; Remington, B. A.; Maddox, B. R.; Bringa, E. M.; Meyers, M. A.

2015-01-01

The structural and mechanical response of metals is intimately connected to phase transformations. For instance, the product of a phase transformation (martensite) is responsible for the extraordinary range of strength and toughness of steel, making it a versatile and important structural material. Although abundant in metals and alloys, the discovery of new phase transformations is not currently a common event and often requires a mix of experimentation, predictive computations, and luck. High-energy pulsed lasers enable the exploration of extreme pressures and temperatures, where such discoveries may lie. The formation of a hexagonal (omega) phase was observed in recovered monocrystalline body-centered cubic tantalum of four crystallographic orientations subjected to an extreme regime of pressure, temperature, and strain-rate. This was accomplished using high-energy pulsed lasers. The omega phase and twinning were identified by transmission electron microscopy at 70 GPa (determined by a corresponding VISAR experiment). It is proposed that the shear stresses generated by the uniaxial strain state of shock compression play an essential role in the transformation. Molecular dynamics simulations show the transformation of small nodules from body-centered cubic to a hexagonal close-packed structure under the same stress state (pressure and shear). PMID:26478106

The fine structural organization of sternal glands of pseudergates and workers in termites (Isoptera): a comparative survey.

PubMed

Quennedey, André; Sillam-Dussès, David; Robert, Alain; Bordereau, Christian

2008-05-01

Thirty-nine species belonging to different families of termites are studied to give a comprehensive view of the evolution of the sternal glands. Several modifications occurring at cuticular and cytological levels are described in neuter castes. The outer epicuticle is always pierced by epicuticular pores. In advanced termites the epicuticular filaments greatly increase in number and length creating a thick layer. The pore canals gradually enlarge while the cuticle changes into a lattice structure lining an extracellular space in which the secretion is stored. Two classes of cells are present in basal termites (Mastotermitidae, Hodotermitidae, Termopsidae and Kalotermitidae) but their glandular structures greatly differ between families. A more complex organization with three classes of cells is found in the Serritermitidae and Rhinotermitidae. A regressive evolution occurs in the Termitidae where only two classes of cells are present. A dual nervous control (campaniform sensilla and neurosecretory fibers) is found in lower termites, except for the Hodotermitidae which have mechanosensory bristles. In the other families, neurosecretory fibers are lacking. A comparison with phylogenetic data is given. A more versatile role of sternal glands in neuter castes is hypothesized.

The role of lipids in host microbe interactions.

PubMed

Lang, Roland; Mattner, Jochen

2017-06-01

Lipids are one of the major subcellular constituents and serve as signal molecules, energy sources, metabolic precursors and structural membrane components in various organisms. The function of lipids can be modified by multiple biochemical processes such as (de-)phosphorylation or (de-)glycosylation, and the organization of fatty acids into distinct cellular pools and subcellular compartments plays a pivotal role for the morphology and function of various cell populations. Thus, lipids regulate, for example, phagosome formation and maturation within host cells and thus, are critical for the elimination of microbial pathogens. Vice versa, microbial pathogens can manipulate the lipid composition of phagosomal membranes in host cells, and thus avoid their delivery to phagolysosomes. Lipids of microbial origin belong also to the strongest and most versatile inducers of mammalian immune responses upon engagement of distinct receptors on myeloid and lymphoid cells. Furthermore, microbial lipid toxins can induce membrane injuries and cell death. Thus, we will review here selected examples for mutual host-microbe interactions within the broad and divergent universe of lipids in microbial defense, tissue injury and immune evasion.

Unidirectional emission in an all-dielectric nanoantenna

NASA Astrophysics Data System (ADS)

Feng, Tianhua; Zhang, Wei; Liang, Zixian; Xu, Yi

2018-03-01

All-dielectric nanoantennas are a promising alternative to plasmonic optical antennas for engineering light emission because of their low-loss nature in the optical spectrum. Nevertheless, it is still challenging to manipulate directional light emission with subwavelength all-dielectric nanoantennas. Here, we propose and numerically demonstrate that a hollow silicon nanodisk can serve as a versatile antenna for directing and enhancing the emission from either an electric or magnetic dipole emitter. When primarily coupled to both electric and magnetic dipole modes of a nanoantenna, broadband nearly-unidirectional emission can be realized by the interference of two modes, which can be spectrally tuned via the geometric parameters in an easy way. More importantly, the emission directions for the magnetic and electric dipole emitters are shown as opposite to each other through control of the phase difference between the induced magnetic and electric dipole modes of the antenna. Meanwhile, the Purcell factors can be enhanced by more than one order of magnitude and high quantum efficiencies can be maintained at the visible spectrum for both kinds of dipole emitters. We further show that these unidirectional emission phenomena can withstand small disorder effects of in-plane dipole orientation and location. Our study provides a simple yet versatile platform that can shape the emission of both magnetic and electric dipole emitters.

Probing membrane protein structure using water polarization transfer solid-state NMR.

PubMed

Williams, Jonathan K; Hong, Mei

2014-10-01

Water plays an essential role in the structure and function of proteins, lipid membranes and other biological macromolecules. Solid-state NMR heteronuclear-detected (1)H polarization transfer from water to biomolecules is a versatile approach for studying water-protein, water-membrane, and water-carbohydrate interactions in biology. We review radiofrequency pulse sequences for measuring water polarization transfer to biomolecules, the mechanisms of polarization transfer, and the application of this method to various biological systems. Three polarization transfer mechanisms, chemical exchange, spin diffusion and NOE, manifest themselves at different temperatures, magic-angle-spinning frequencies, and pulse irradiations. Chemical exchange is ubiquitous in all systems examined so far, and spin diffusion plays the key role in polarization transfer within the macromolecule. Tightly bound water molecules with long residence times are rare in proteins at ambient temperature. The water polarization-transfer technique has been used to study the hydration of microcrystalline proteins, lipid membranes, and plant cell wall polysaccharides, and to derive atomic-resolution details of the kinetics and mechanism of ion conduction in channels and pumps. Using this approach, we have measured the water polarization transfer to the transmembrane domain of the influenza M2 protein to obtain information on the structure of this tetrameric proton channel. At short mixing times, the polarization transfer rates are site-specific and depend on the pH, labile protons, sidechain conformation, as well as the radial position of the residues in this four-helix bundle. Despite the multiple dependences, the initial transfer rates reflect the periodic nature of the residue positions from the water-filled pore, thus this technique provides a way of gleaning secondary structure information, helix tilt angle, and the oligomeric structure of membrane proteins. Copyright © 2014 Elsevier Inc. All rights reserved.

Flow directionality, mountain barriers and functional traits determine diatom metacommunity structuring of high mountain streams.

PubMed

Dong, Xiaoyu; Li, Bin; He, Fengzhi; Gu, Yuan; Sun, Meiqin; Zhang, Haomiao; Tan, Lu; Xiao, Wen; Liu, Shuoran; Cai, Qinghua

2016-04-19

Stream metacommunities are structured by a combination of local (environmental filtering) and regional (dispersal) processes. The unique characters of high mountain streams could potentially determine metacommunity structuring, which is currently poorly understood. Aiming at understanding how these characters influenced metacommunity structuring, we explored the relative importance of local environmental conditions and various dispersal processes, including through geographical (overland), topographical (across mountain barriers) and network (along flow direction) pathways in shaping benthic diatom communities. From a trait perspective, diatoms were categorized into high-profile, low-profile and motile guild to examine the roles of functional traits. Our results indicated that both environmental filtering and dispersal processes influenced metacommunity structuring, with dispersal contributing more than environmental processes. Among the three pathways, stream corridors were primary pathway. Deconstructive analysis suggested different responses to environmental and spatial factors for each of three ecological guilds. However, regardless of traits, dispersal among streams was limited by mountain barriers, while dispersal along stream was promoted by rushing flow in high mountain stream. Our results highlighted that directional processes had prevailing effects on metacommunity structuring in high mountain streams. Flow directionality, mountain barriers and ecological guilds contributed to a better understanding of the roles that mountains played in structuring metacommunity.

Spontaneous wrinkling in azlactone-based functional polymer thin films in 2D and 3D geometries for guided nanopatterning

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

Ramanathan, Muruganathan; Lokitz, Bradley S.; Messman, Jamie M.

We report a simple, one step process for developing wrinkling patterns in azlactone-based polymer thin films and brushes in 2D and 3D surfaces. The polymer used in this work wrinkles spontaneously upon deposition and solidification on a substrate without applying any external strain to the substrate, with the mode of deposition defining the direction of the wrinkles. Wrinkle formation is shown to occur on a variety of substrates over large areas. We also find that a very thin brush-like layer of an azlactone-containing block copolymer also exhibits wrinkled topology. Given the spontaneity and versatility of wrinkle formation, we further demonstratemore » two proofs-of-concept, i) that these periodic wrinkled structures are not limited to planar surfaces, but are also developed in complex geometries including tubes, cones and other 3D structures; and ii) that this one-step wrinkling process can be used to guide the deposition of metal nanoparticles and quantum dots, creating a periodic, nanopatterned film.« less

Alternative Conformations of Cytochrome c: Structure, Function, and Detection.

PubMed

Hannibal, Luciana; Tomasina, Florencia; Capdevila, Daiana A; Demicheli, Verónica; Tórtora, Verónica; Alvarez-Paggi, Damián; Jemmerson, Ronald; Murgida, Daniel H; Radi, Rafael

2016-01-26

Cytochrome c (cyt c) is a cationic hemoprotein of ∼100 amino acid residues that exhibits exceptional functional versatility. While its primary function is electron transfer in the respiratory chain, cyt c is also recognized as a key component of the intrinsic apoptotic pathway, the mitochondrial oxidative protein folding machinery, and presumably as a redox sensor in the cytosol, along with other reported functions. Transition to alternative conformations and gain-of-peroxidase activity are thought to further enable the multiple functions of cyt c and its translocation across cellular compartments. In vitro, direct interactions of cyt c with cardiolipin, post-translational modifications such as tyrosine nitration, phosphorylation, methionine sulfoxidation, mutations, and even fine changes in electrical fields lead to a variety of conformational states that may be of biological relevance. The identification of these alternative conformations and the elucidation of their functions in vivo continue to be a major challenge. Here, we unify the knowledge of the structural flexibility of cyt c that supports functional moonlighting and review biochemical and immunochemical evidence confirming that cyt c undergoes conformational changes during normal and altered cellular homeostasis.

Correlates of anal sex roles among Malay and Chinese MSM in Kuala Lumpur, Malaysia.

PubMed

Dangerfield, Derek T; Gravitt, Patti; Rompalo, Anne M; Tai, Raymond; Lim, Sin How

2016-03-01

Identifying roles for anal sex is an important issue for populations of MSM. We describe the prevalence of identifying as being 'top', 'bottom', 'versatile', or 'don't know/not applicable' among Malay and Chinese MSM in Kuala Lumpur, Malaysia, and behavioural outcomes according to these labels for sexual role identity. Data analysis was conducted on a survey administered during weekly outreach throughout Kuala Lumpur in 2012. Pearson's Chi square tests were used to compare demographic and behavioural characteristics of MSM who reported roles for anal sex. Binary logistic regression was used to explore the odds of behavioural outcomes among MSM who identified as 'bottom', 'versatile,' and 'don't know' compared to MSM who reported that 'top' was their sexual role. Labels for anal sex roles were significantly associated with condom use for last anal sex. Among MSM who used labels for anal sex roles, MSM who identified as 'bottom' had highest level of not using condoms for last anal sex (24.1%, p = .045). In binary logistic regression model, identifying as 'top' was significantly associated with reporting using a condom during last anal sex and reported consistent condom use for anal sex in the past six months (p = .039 and .017, respectively). With regard to sexual role identity, some MSM may be a part of a special subgroup of at-risk men to be targeted. Future research should evaluate the origins, meanings, and perceptions of these labels, and the developmental process of how these MSM identify with any of these categories. Research should also uncover condom use decision making with regard to these labels for sexual positioning. © The Author(s) 2016.

Silk constructs for delivery of muskuloskeletal therapeutics

PubMed Central

Meinel, Lorenz; Kaplan, David L.

2012-01-01

Silk fibroin (SF) is a biopolymer with distinguishing features from many other bio- as well as synthetic polymers. From a biomechanical and drug delivery perspective, SF combines remarkable versatility for scaffolding (solid implants, hydrogels, threads, solutions), with advanced mechanical properties and good stabilization and controlled delivery of entrapped protein and small molecule drugs, respectively. It is this combination of mechanical and pharmaceutical features which render SF so exciting for biomedical applications. his pattern along with the versatility of this biopolymer have been translated into progress for musculoskeletal applications. We review the use and potential of silk fibroin for systemic and localized delivery of therapeutics in diseases affecting the musculoskeletal system. We also present future directions for this biopolymer as well as the necessary research and development steps for their achievement. PMID:22522139

A versatile cis-acting inverter module for synthetic translational switches.

PubMed

Endo, Kei; Hayashi, Karin; Inoue, Tan; Saito, Hirohide

2013-01-01

Artificial genetic switches have been designed and tuned individually in living cells. A method to directly invert an existing OFF switch to an ON switch should be highly convenient to construct complex circuits from well-characterized modules, but developing such a technique has remained a challenge. Here we present a cis-acting RNA module to invert the function of a synthetic translational OFF switch to an ON switch in mammalian cells. This inversion maintains the property of the parental switch in response to a particular input signal. In addition, we demonstrate simultaneous and specific expression control of both the OFF and ON switches. The module fits the criteria of universality and expands the versatility of mRNA-based information processing systems developed for artificially controlling mammalian cellular behaviour.

Copper-catalyzed trifluoromethylthiolation of aryl halides with diverse directing groups.

PubMed

Xu, Jiabin; Mu, Xin; Chen, Pinhong; Ye, Jinxing; Liu, Guosheng

2014-08-01

The expansion of cross-coupling components in Cu-catalyzed C-X bond forming reactions have received much attention recently. A novel Cu-catalyzed trifluoromethylthiolation of aryl bromides and iodides with the assistance of versatile directing groups such as pyridyl, methyl ester, amide, imine and oxime was reported. CuBr was used as the catalyst, and 1,10-phenanthroline as the ligand. By changing the solvent from acetonitrile to DMF, the coupling process could even take place at room temperature.

Unexpected tautomeric equilibria of the carbanion-enamine intermediate in pyruvate oxidase highlight unrecognized chemical versatility of thiamin

PubMed Central

Meyer, Danilo; Neumann, Piotr; Koers, Eline; Sjuts, Hanno; Lüdtke, Stefan; Sheldrick, George M.; Ficner, Ralf; Tittmann, Kai

2012-01-01

Thiamin diphosphate, the vitamin B1 coenzyme, plays critical roles in fundamental metabolic pathways that require acyl carbanion equivalents. Studies on chemical models and enzymes had suggested that these carbanions are resonance-stabilized as enamines. A crystal structure of this intermediate in pyruvate oxidase at 1.1 Å resolution now challenges this paradigm by revealing that the enamine does not accumulate. Instead, the intermediate samples between the ketone and the carbanion both interlocked in a tautomeric equilibrium. Formation of the keto tautomer is associated with a loss of aromaticity of the cofactor. The alternate confinement of electrons to neighboring atoms rather than π-conjugation seems to be of importance for the enzyme-catalyzed, redox-coupled acyl transfer to phosphate, which requires a dramatic inversion of polarity of the reacting substrate carbon in two subsequent catalytic steps. The ability to oscillate between a nucleophilic (carbanion) and an electrophilic (ketone) substrate center highlights a hitherto unrecognized versatility of the thiamin cofactor. It remains to be studied whether formation of the keto tautomer is a general feature of all thiamin enzymes, as it could provide for stable storage of the carbanion state, or whether this feature represents a specific trait of thiamin oxidases. In addition, the protonation state of the two-electron reduced flavin cofactor can be fully assigned, demonstrating the power of high-resolution cryocrystallography for elucidation of enzymatic mechanisms. PMID:22730460

DKWSLLL, a versatile DXXXLL-type signal with distinct roles in the Cu(+)-regulated trafficking of ATP7B.

PubMed

Lalioti, Vasiliki; Hernandez-Tiedra, Sonia; Sandoval, Ignacio V

2014-08-01

In the liver, the P-type ATPase and membrane pump ATP7B plays a crucial role in Cu(+) donation to cuproenzymes and in the elimination of excess Cu(+). ATP7B is endowed with a COOH-cytoplasmic (DE)XXXLL-type traffic signal. We find that accessory (Lys -3, Trp -2, Ser -1 and Leu +2) and canonical (D -4, Leu 0 and Leu +1) residues confer the DKWSLLL signal with the versatility required for the Cu(+)-regulated cycling of ATP7B between the trans-Golgi network (TGN) and the plasma membrane (PM). The separate mutation of these residues caused a disruption of the signal, resulting in different ATP7B distribution phenotypes. These phenotypes indicate the key roles of specific residues at separate steps of ATP7B trafficking, including sorting at the TGN, transport from the TGN to the PM and its endocytosis, and recycling to the TGN and PM. The distinct roles of ATP7B in the TGN and PM and the variety of phenotypes caused by the mutation of the canonical and accessory residues of the DKWSLLL signal can explain the separate or joined presentation of Wilson's cuprotoxicosis and the dysfunction of the cuproenzymes that accept Cu(+) at the TGN. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

A versatile expression vector for the growth and amplification of unmodified phage display polypeptides.

PubMed

Winton, Alexander J; Baptiste, Janae L; Allen, Mark A

2018-09-01

Proteins and polypeptides represent nature's most complex and versatile polymer. They provide complicated shapes, diverse chemical functionalities, and tightly regulated and controlled sizes. Several disease states are related to the misfolding or overproduction of polypeptides and yet polypeptides are present in several therapeutic molecules. In addition to biological roles; short chain polypeptides have been shown to interact with and drive the bio-inspired synthesis or modification of inorganic materials. This paper outlines the development of a versatile cloning vector which allows for the expression of a short polypeptide by controlling the incorporation of a desired DNA coding insert. As a demonstration of the efficacy of the expression system, a solid binding polypeptide identified from M13 phage display was expressed and purified. The solid binding polypeptide was expressed as a soluble 6xHis-SUMO tagged construct. Expression was performed in E. coli using auto-induction followed by Ni-NTA affinity chromatography and ULP1 protease cleavage. Methodology demonstrates the production of greater than 8 mg of purified polypeptide per liter of E. coli culture. Isotopic labeling of the peptide is also demonstrated. The versatility of the designed cloning vector, use of the 6xHis-SUMO solubility partner, bacterial expression in auto-inducing media and the purification methodology make this expressionun vector a readily scalable and user-friendly system for the creation of desired peptide domains. Copyright © 2018. Published by Elsevier Inc.

Structure-related frustrated magnetism of nanosized polyoxometalates: aesthetics and properties in harmony.

PubMed

Kögerler, Paul; Tsukerblat, Boris; Müller, Achim

2010-01-07

The structural versatility characterizing polyoxometalate chemistry, in combination with the option to deliberately use well-defined building blocks, serves as the foundation for the generation of a large family of magnetic clusters, frequently comprising highly symmetric spin arrays. If the spin centers are coupled by antiferromagnetic exchange, some of these systems exhibit spin frustration, which can result in novel magnetic properties of purely molecular origins. We discuss here the magnetic properties of selected nanosized polyoxometalate clusters featuring spin triangles as their magnetic 'building blocks' or fragments. This includes unique porous Keplerate clusters of the type {(Mo)Mo(5)}(12)M(30) (M = Fe(III), Cr(III), V(IV)) with the spin centers defining a regular icosidodecahedron and the {V(15)As(6)}-type cluster sphere containing a single equilateral spin triangle; these species are widely discussed and studied in the literature for their role in materials science as molecular representations of Kagomé lattices and in relation to quantum computing, respectively. Exhibiting fascinating and unique structural features, these magnetic molecules allow the study of the implications of frustrated spin ordering. Furthermore, this perspective covers the impact of spin frustration on the degeneracy of the ground state and related problems, namely strong magnetic anisotropy and the interplay of antisymmetric exchange and structural Jahn-Teller effects.

Facilely Fabricating Multifunctional N-Enriched Carbon.

PubMed

Wan, Mi Mi; Sun, Xiao Dan; Li, Yan Yan; Zhou, Jun; Wang, Ying; Zhu, Jian Hua

2016-01-20

A new synthetic strategy, named "carbonization in limited space" and based on the specific interaction between eutectic salt and dual-ionic liquids (dual-ILs), is reported in this article. N-Containing dual-ILs (1,4-diethyl-1,4-diazaniabicyclo[2,2,2]octane imidazolide-4,5-dicyanoiazolide, [2C2DABCO](2+)[Im](-)[CN-Im](-)) were synthesized as new carbon-nitrogen precursors, while eutectic salt was chosen as a reuseable template in order to facilely fabricate the N-doped porous carbon with sheetlike morphology. Nitrogen can be directly and efficiently incorporated into the porous carbon, resulting in the materials with suitable N content, tunable pore structure, and controllable thickness of sheet as well as high surface area. They exhibited good performance as electrodes for supercapacitors, photocatalysts in degradation of methyl orange (MO) under visible light, and the sorbent to capture tobacco-specific N-nitrosamines (TSNAs) in solution, offering a new simplified but effective method to prepare versatile carbon material.

Determination of the Goos-Hanchen shift in dielectric waveguides via photo emission electron microscopy in the visible spectrum

DOE PAGES

Stenmark, Theodore; Word, R. C.; Konenkamp, R.

2016-02-16

Photoemission Electron Microscopy (PEEM) is a versatile tool that relies on the photoelectric effect to produce high-resolution images. Pulse lasers allow for multi-photon PEEM where multiple photons are required excite a single electron. This non-linear process can directly image the near field region of electromagnetic fields in materials. We use this ability here to analyze wave propagation in a linear dielectric waveguide with wavelengths of 410nm and 780nm. The propagation constant of the waveguide can be extracted from the interference pattern created by the coupled and incident light and shows distinct polarization dependence. Furthermore, the electromagnetic field interaction at themore » boundaries can then be deduced which is essential to understand power flow in wave guiding structures. These results match well with simulations using finite element techniques.« less

Guided post-acceleration of laser-driven ions by a miniature modular structure

PubMed Central

Kar, Satyabrata; Ahmed, Hamad; Prasad, Rajendra; Cerchez, Mirela; Brauckmann, Stephanie; Aurand, Bastian; Cantono, Giada; Hadjisolomou, Prokopis; Lewis, Ciaran L. S.; Macchi, Andrea; Nersisyan, Gagik; Robinson, Alexander P. L.; Schroer, Anna M.; Swantusch, Marco; Zepf, Matt; Willi, Oswald; Borghesi, Marco

2016-01-01

All-optical approaches to particle acceleration are currently attracting a significant research effort internationally. Although characterized by exceptional transverse and longitudinal emittance, laser-driven ion beams currently have limitations in terms of peak ion energy, bandwidth of the energy spectrum and beam divergence. Here we introduce the concept of a versatile, miniature linear accelerating module, which, by employing laser-excited electromagnetic pulses directed along a helical path surrounding the laser-accelerated ion beams, addresses these shortcomings simultaneously. In a proof-of-principle experiment on a university-scale system, we demonstrate post-acceleration of laser-driven protons from a flat foil at a rate of 0.5 GeV m−1, already beyond what can be sustained by conventional accelerator technologies, with dynamic beam collimation and energy selection. These results open up new opportunities for the development of extremely compact and cost-effective ion accelerators for both established and innovative applications. PMID:27089200

From the generalized reflection law to the realization of perfect anomalous reflectors

PubMed Central

Díaz-Rubio, Ana; Asadchy, Viktar S.; Elsakka, Amr; Tretyakov, Sergei A.

2017-01-01

The use of the generalized Snell’s law opens wide possibilities for the manipulation of transmitted and reflected wavefronts. However, known structures designed to shape reflection wavefronts suffer from significant parasitic reflections in undesired directions. We explore the limitations of the existing solutions for the design of passive planar reflectors and demonstrate that strongly nonlocal response is required for perfect performance. A new paradigm for the design of perfect reflectors based on energy surface channeling is introduced. We realize and experimentally verify a perfect design of an anomalously reflective surface using an array of rectangular metal patches backed by a metallic plate. This conceptually new mechanism for wavefront manipulation allows the design of thin perfect reflectors, offering a versatile design method applicable to other scenarios, such as focusing reflectors, surface wave manipulations, or metasurface holograms, extendable to other frequencies. PMID:28819642

HEALPix: A Framework for High-Resolution Discretization and Fast Analysis of Data Distributed on the Sphere

NASA Technical Reports Server (NTRS)

Gorski, K. M.; Hivon, Eric; Banday, A. J.; Wandelt, Benjamin D.; Hansen, Frode K.; Reinecke, Mstvos; Bartelmann, Matthia

2005-01-01

HEALPix the Hierarchical Equal Area isoLatitude Pixelization is a versatile structure for the pixelization of data on the sphere. An associated library of computational algorithms and visualization software supports fast scientific applications executable directly on discretized spherical maps generated from very large volumes of astronomical data. Originally developed to address the data processing and analysis needs of the present generation of cosmic microwave background experiments (e.g., BOOMERANG, WMAP), HEALPix can be expanded to meet many of the profound challenges that will arise in confrontation with the observational output of future missions and experiments, including, e.g., Planck, Herschel, SAFIR, and the Beyond Einstein inflation probe. In this paper we consider the requirements and implementation constraints on a framework that simultaneously enables an efficient discretization with associated hierarchical indexation and fast analysis/synthesis of functions defined on the sphere. We demonstrate how these are explicitly satisfied by HEALPix.

The styrene-maleic acid copolymer: a versatile tool in membrane research.

PubMed

Dörr, Jonas M; Scheidelaar, Stefan; Koorengevel, Martijn C; Dominguez, Juan J; Schäfer, Marre; van Walree, Cornelis A; Killian, J Antoinette

2016-01-01

A new and promising tool in membrane research is the detergent-free solubilization of membrane proteins by styrene-maleic acid copolymers (SMAs). These amphipathic molecules are able to solubilize lipid bilayers in the form of nanodiscs that are bounded by the polymer. Thus, membrane proteins can be directly extracted from cells in a water-soluble form while conserving a patch of native membrane around them. In this review article, we briefly discuss current methods of membrane protein solubilization and stabilization. We then zoom in on SMAs, describe their physico-chemical properties, and discuss their membrane-solubilizing effect. This is followed by an overview of studies in which SMA has been used to isolate and investigate membrane proteins. Finally, potential future applications of the methodology are discussed for structural and functional studies on membrane proteins in a near-native environment and for characterizing protein-lipid and protein-protein interactions.

Advanced Nanoindentation Testing for Studying Strain-Rate Sensitivity and Activation Volume

NASA Astrophysics Data System (ADS)

Maier-Kiener, Verena; Durst, Karsten

2017-11-01

Nanoindentation became a versatile tool for testing local mechanical properties beyond hardness and modulus. By adapting standard nanoindentation test methods, simple protocols capable of probing thermally activated deformation processes can be accomplished. Abrupt strain-rate changes within one indentation allow determining the strain-rate dependency of hardness at various indentation depths. For probing lower strain-rates and excluding thermal drift influences, long-term creep experiments can be performed by using the dynamic contact stiffness for determining the true contact area. From both procedures hardness and strain-rate, and consequently strain-rate sensitivity and activation volume can be reliably deducted within one indentation, permitting information on the locally acting thermally activated deformation mechanism. This review will first discuss various testing protocols including possible challenges and improvements. Second, it will focus on different examples showing the direct influence of crystal structure and/or microstructure on the underlying deformation behavior in pure and highly alloyed material systems.

The "Speedy" Synthesis of Atom-Specific (15)N Imino/Amido-Labeled RNA.

PubMed

Neuner, Sandro; Santner, Tobias; Kreutz, Christoph; Micura, Ronald

2015-08-10

Although numerous reports on the synthesis of atom-specific (15)N-labeled nucleosides exist, fast and facile access to the corresponding phosphoramidites for RNA solid-phase synthesis is still lacking. This situation represents a severe bottleneck for NMR spectroscopic investigations on functional RNAs. Here, we present optimized procedures to speed up the synthesis of (15)N(1) adenosine and (15)N(1) guanosine amidites, which are the much needed counterparts of the more straightforward-to-achieve (15)N(3) uridine and (15)N(3) cytidine amidites in order to tap full potential of (1)H/(15)N/(15)N-COSY experiments for directly monitoring individual Watson-Crick base pairs in RNA. Demonstrated for two preQ1 riboswitch systems, we exemplify a versatile concept for individual base-pair labeling in the analysis of conformationally flexible RNAs when competing structures and conformational dynamics are encountered. © 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim.

The “Speedy” Synthesis of Atom-Specific 15N Imino/Amido-Labeled RNA

PubMed Central

Kreutz, Christoph; Micura, Ronald

2016-01-01

Although numerous reports on the synthesis of atom-specific 15N-labeled nucleosides exist, fast and facile access to the corresponding phosphoramidites for RNA solid-phase synthesis is still lacking. This situation represents a severe bottleneck for NMR spectroscopic investigations on functional RNAs. Here, we present optimized procedures to speed up the synthesis of 15N(1) adenosine and 15N(1) guanosine amidites, which are the much needed counterparts of the more straightforward-to-achieve 15N(3) uridine and 15N(3) cytidine amidites in order to tap full potential of 1H/15N/15N-COSY experiments for directly monitoring individual Watson–Crick base pairs in RNA. Demonstrated for two preQ1 riboswitch systems, we exemplify a versatile concept for individual base-pair labeling in the analysis of conformationally flexible RNAs when competing structures and conformational dynamics are encountered. PMID:26237536

Electrostatics at the nanoscale.

PubMed

Walker, David A; Kowalczyk, Bartlomiej; de la Cruz, Monica Olvera; Grzybowski, Bartosz A

2011-04-01

Electrostatic forces are amongst the most versatile interactions to mediate the assembly of nanostructured materials. Depending on experimental conditions, these forces can be long- or short-ranged, can be either attractive or repulsive, and their directionality can be controlled by the shapes of the charged nano-objects. This Review is intended to serve as a primer for experimentalists curious about the fundamentals of nanoscale electrostatics and for theorists wishing to learn about recent experimental advances in the field. Accordingly, the first portion introduces the theoretical models of electrostatic double layers and derives electrostatic interaction potentials applicable to particles of different sizes and/or shapes and under different experimental conditions. This discussion is followed by the review of the key experimental systems in which electrostatic interactions are operative. Examples include electroactive and "switchable" nanoparticles, mixtures of charged nanoparticles, nanoparticle chains, sheets, coatings, crystals, and crystals-within-crystals. Applications of these and other structures in chemical sensing and amplification are also illustrated.

Patterned Colloidal Photonic Crystals.

PubMed

Hou, Jue; Li, Mingzhu; Song, Yanlin

2018-03-01

Colloidal photonic crystals (PCs) have been well developed because they are easy to prepare, cost-effective, and versatile with regards to modification and functionalization. Patterned colloidal PCs contribute a novel approach to constructing high-performance PC devices with unique structures and specific functions. In this review, an overview of the strategies for fabricating patterned colloidal PCs, including patterned substrate-induced assembly, inkjet printing, and selective immobilization and modification, is presented. The advantages of patterned PC devices are also discussed in detail, for example, improved detection sensitivity and response speed of the sensors, control over the flow direction and wicking rate of microfluidic channels, recognition of cross-reactive molecules through an array-patterned microchip, fabrication of display devices with tunable patterns, well-arranged RGB units, and wide viewing-angles, and the ability to construct anti-counterfeiting devices with different security strategies. Finally, the perspective of future developments and challenges is presented. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Spherical-earth gravity and magnetic anomaly modeling by Gauss-Legendre quadrature integration

NASA Technical Reports Server (NTRS)

Von Frese, R. R. B.; Hinze, W. J.; Braile, L. W.; Luca, A. J.

1981-01-01

Gauss-Legendre quadrature integration is used to calculate the anomalous potential of gravity and magnetic fields and their spatial derivatives on a spherical earth. The procedure involves representation of the anomalous source as a distribution of equivalent point gravity poles or point magnetic dipoles. The distribution of equivalent point sources is determined directly from the volume limits of the anomalous body. The variable limits of integration for an arbitrarily shaped body are obtained from interpolations performed on a set of body points which approximate the body's surface envelope. The versatility of the method is shown by its ability to treat physical property variations within the source volume as well as variable magnetic fields over the source and observation surface. Examples are provided which illustrate the capabilities of the technique, including a preliminary modeling of potential field signatures for the Mississippi embayment crustal structure at 450 km.

Ketone-DNA: a versatile postsynthetic DNA decoration platform.

PubMed

Dey, S; Sheppard, T L

2001-12-13

[reaction: see text] A general strategy for the functional diversification of DNA oligonucleotides under physiological conditions was developed. We describe the synthesis of DNA molecules bearing ketone ports (ketone-DNA) and the efficient postsynthetic decoration of ketone-DNA with structurally diverse aminooxy compounds.

Parameterizing A Surface Water Model for Multiwalled Carbon Nanotubes

EPA Science Inventory

The unique electronic, mechanical, and structural properties of carbon nanotubes (CNTs) has lead to increasing production of these versatile materials; currently, the use of carbon-based nanomaterials in consumer products is second only to that of nano-scale silver. Although ther...

Straightforward and precise approach to replicate complex hierarchical structures from plant surfaces onto soft matter polymer

PubMed Central

Speck, Thomas; Bohn, Holger F.

2018-01-01

The surfaces of plant leaves are rarely smooth and often possess a species-specific micro- and/or nano-structuring. These structures usually influence the surface functionality of the leaves such as wettability, optical properties, friction and adhesion in insect–plant interactions. This work presents a simple, convenient, inexpensive and precise two-step micro-replication technique to transfer surface microstructures of plant leaves onto highly transparent soft polymer material. Leaves of three different plants with variable size (0.5–100 µm), shape and complexity (hierarchical levels) of their surface microstructures were selected as model bio-templates. A thermoset epoxy resin was used at ambient conditions to produce negative moulds directly from fresh plant leaves. An alkaline chemical treatment was established to remove the entirety of the leaf material from the cured negative epoxy mould when necessary, i.e. for highly complex hierarchical structures. Obtained moulds were filled up afterwards with low viscosity silicone elastomer (PDMS) to obtain positive surface replicas. Comparative scanning electron microscopy investigations (original plant leaves and replicated polymeric surfaces) reveal the high precision and versatility of this replication technique. This technique has promising future application for the development of bioinspired functional surfaces. Additionally, the fabricated polymer replicas provide a model to systematically investigate the structural key points of surface functionalities. PMID:29765666

Growth of 2D Mesoporous Polyaniline with Controlled Pore Structures on Ultrathin MoS2 Nanosheets by Block Copolymer Self-Assembly in Solution.

PubMed

Tian, Hao; Zhu, Shuyan; Xu, Fugui; Mao, Wenting; Wei, Hao; Mai, Yiyong; Feng, Xinliang

2017-12-20

The development of versatile strategies toward two-dimensional (2D) porous nanocomposites with tunable pore structures draws immense scientific attention in view of their attractive physiochemical properties and a wide range of promising applications. This paper describes a self-assembly approach for the directed growth of mesoporous polyaniline (PANi) with tunable pore structures and sizes on ultrathin freestanding MoS 2 nanosheets in solution, which produces 2D mesoporous PANi/MoS 2 nanocomposites. The strategy employs spherical and cylindrical micelles, which are formed by the controlled solution self-assembly of block copolymers, as the soft templates for the construction of well-defined spherical and cylindrical mesopores in the 2D PANi/MoS 2 nanocomposites, respectively. With potential applications as supercapacitor electrode materials, the resultant 2D composites show excellent capacitive performance with a maximum capacitance of 500 F g -1 at a current density of 0.5 A g -1 , good rate performance, as well as outstanding stability for charge-discharge cycling. Moreover, the 2D mesoporous nanocomposites offer an opportunity for the study on the influence of different pore structures on their capacitive performance, which helps to understand the pore structure-property relationship of 2D porous electrode materials and to achieve their electrochemical performance control.

Label-Free, LC-MS-Based Assays to Quantitate Small-Molecule Antagonist Binding to the Mammalian BLT1 Receptor.

PubMed

Chen, Xun; Stout, Steven; Mueller, Uwe; Boykow, George; Visconti, Richard; Siliphaivanh, Phieng; Spencer, Kerrie; Presland, Jeremy; Kavana, Michael; Basso, Andrea D; McLaren, David G; Myers, Robert W

2017-08-01

We have developed and validated label-free, liquid chromatography-mass spectrometry (LC-MS)-based equilibrium direct and competition binding assays to quantitate small-molecule antagonist binding to recombinant human and mouse BLT1 receptors expressed in HEK 293 cell membranes. Procedurally, these binding assays involve (1) equilibration of the BLT1 receptor and probe ligand, with or without a competitor; (2) vacuum filtration through cationic glass fiber filters to separate receptor-bound from free probe ligand; and (3) LC-MS analysis in selected reaction monitoring mode for bound probe ligand quantitation. Two novel, optimized probe ligands, compounds 1 and 2, were identified by screening 20 unlabeled BLT1 antagonists for direct binding. Saturation direct binding studies confirmed the high affinity, and dissociation studies established the rapid binding kinetics of probe ligands 1 and 2. Competition binding assays were established using both probe ligands, and the affinities of structurally diverse BLT1 antagonists were measured. Both binding assay formats can be executed with high specificity and sensitivity and moderate throughput (96-well plate format) using these approaches. This highly versatile, label-free method for studying ligand binding to membrane-associated receptors should find broad application as an alternative to traditional methods using labeled ligands.

Active Learning through Role Playing: Virtual Babies in a Child Development Course

ERIC Educational Resources Information Center

Poling, Devereaux A.; Hupp, Julie M.

2009-01-01

The authors designed an active learning project for a child development course in which students apply core concepts to a hypothetical baby they "raise" during the term. Students applied developmental topics to their unique, developing child. The project fostered student learning and enthusiasm for the material. The project's versatility makes it…

Carbon-based hybrid nanogels: a synergistic nanoplatform for combined biosensing, bioimaging, and responsive drug delivery.

PubMed

Wang, Hui; Chen, Qianwang; Zhou, Shuiqin

2018-06-05

Nanosized crosslinked polymer networks, named as nanogels, are playing an increasingly important role in a diverse range of applications by virtue of their porous structures, large surface area, good biocompatibility and responsiveness to internal and/or external chemico-physical stimuli. Recently, a variety of carbon nanomaterials, such as carbon quantum dots, graphene/graphene oxide nanosheets, fullerenes, carbon nanotubes, and nanodiamonds, have been embedded into responsive polymer nanogels, in order to integrate the unique electro-optical properties of carbon nanomaterials with the merits of nanogels into a single hybrid nanogel system for improvement of their applications in nanomedicine. A vast number of studies have been pursued to explore the applications of carbon-based hybrid nanogels in biomedical areas for biosensing, bioimaging, and smart drug carriers with combinatorial therapies and/or theranostic ability. New synthetic methods and structures have been developed to prepare carbon-based hybrid nanogels with versatile properties and functions. In this review, we summarize the latest developments and applications and address the future perspectives of these carbon-based hybrid nanogels in the biomedical field.

Experimental Aspects of Colloidal Interactions in Mixed Systems of Liposome and Inorganic Nanoparticle and Their Applications

PubMed Central

Michel*, Raphael; Gradzielski*, Michael

2012-01-01

In the past few years, growing attention has been devoted to the study of the interactions taking place in mixed systems of phospholipid membranes (for instance in the form of vesicles) and hard nanoparticles (NPs). In this context liposomes (vesicles) may serve as versatile carriers or as a model system for biological membranes. Research on these systems has led to the observation of novel hybrid structures whose morphology strongly depends on the charge, composition and size of the interacting colloidal species as well as on the nature (pH, ionic strength) of their dispersing medium. A central role is played by the phase behaviour of phospholipid bilayers which have a tremendous influence on the liposome properties. Another central aspect is the incorporation of nanoparticles into vesicles, which is intimately linked to the conditions required for transporting a nanoparticle through a membrane. Herein, we review recent progress made on the investigations of the interactions in liposome/nanoparticle systems focusing on the particularly interesting structures that are formed in these hybrid systems as well as their potential applications. PMID:23109874

Zn(x)Cd(1-x)Se nanomultipods with tunable band gaps: synthesis and first-principles calculations.

PubMed

Wei, Hao; Su, Yanjie; Han, Ziyi; Li, Tongtong; Ren, Xinglong; Yang, Zhi; Wei, Liangming; Cong, Fengsong; Zhang, Yafei

2013-06-14

In this paper, we demonstrate that ZnxCd1-xSe nanomultipods can be synthesized via a facile and nontoxic solution-based method. Interesting aspects of composition, morphology and optical properties were deeply explored. The value of Zn/(Zn+Cd) could be altered across the entire range from 0.08 to 0.86 by varying the ratio of cation precursor contents. The band gap energy could be linearly tuned from 1.88 to 2.48 eV with respect to the value of Zn/(Zn+Cd). The experiment also showed that oleylamine played a dominant role in the formation of multipod structure. A possible growth mechanism was further suggested. First-principles calculations of band gap energy and density of states in the Vienna ab initio simulation package code were performed to verify the experimental variation tendency of the band gap. Computational results indicated that dissimilarities of electronic band structures and orbital constitutions determined the tunable band gap of the as-synthesized nanomultipod, which might be promising for versatile applications in relevant areas of solar cells, biomedicine, sensors, catalysts and so on.

The evolving role of hyaluronic acid fillers for facial volume restoration and contouring: a Canadian overview

PubMed Central

Muhn, Channy; Rosen, Nathan; Solish, Nowell; Bertucci, Vince; Lupin, Mark; Dansereau, Alain; Weksberg, Fred; Remington, B Kent; Swift, Arthur

2012-01-01

Recent advancements, including more versatile facial fillers, refined injection techniques and the adoption of a global facial approach, have contributed to improved patient outcome and increased patient satisfaction. Nine Canadian specialists (eight dermatologists, one plastic surgeon) collaborated to develop an overview on volume restoration and contouring based on published literature and their collective clinical experience. The specialists concurred that optimal results in volume restoration and contouring depend on correcting deficiencies at various layers of the facial envelope. This includes creating a foundation for deep structural support in the supraperiosteal or submuscular plane; volume repletion of subcutaneous fat compartments; and the reestablishment of dermal and subdermal support to minimize cutaneous rhytids, grooves and furrows. It was also agreed that volume restoration and contouring using a global facial approach is essential to create a natural, youthful appearance in facial aesthetics. A comprehensive non-surgical approach should therefore incorporate combining fillers such as high-viscosity, low-molecular-weight hyaluronic acid (LMWHA) for structural support and hyaluronic acid (HA) for lines, grooves and furrows with neuromodulators, lasers and energy devices. PMID:23071398

Implementation and Development of the Incremental Hole Drilling Method for the Measurement of Residual Stress in Thermal Spray Coatings

NASA Astrophysics Data System (ADS)

Valente, T.; Bartuli, C.; Sebastiani, M.; Loreto, A.

2005-12-01

The experimental measurement of residual stresses originating within thick coatings deposited by thermal spray on solid substrates plays a role of fundamental relevance in the preliminary stages of coating design and process parameters optimization. The hole-drilling method is a versatile and widely used technique for the experimental determination of residual stress in the most superficial layers of a solid body. The consolidated procedure, however, can only be implemented for metallic bulk materials or for homogeneous, linear elastic, and isotropic materials. The main objective of the present investigation was to adapt the experimental method to the measurement of stress fields built up in ceramic coatings/metallic bonding layers structures manufactured by plasma spray deposition. A finite element calculation procedure was implemented to identify the calibration coefficients necessary to take into account the elastic modulus discontinuities that characterize the layered structure through its thickness. Experimental adjustments were then proposed to overcome problems related to the low thermal conductivity of the coatings. The number of calculation steps and experimental drilling steps were finally optimized.

Consideration of the Aluminum Distribution in Zeolites in Theoretical and Experimental Catalysis Research

DOE PAGES

Knott, Brandon C.; Nimlos, Claire T.; Robichaud, David J.; ...

2017-12-11

Research efforts in zeolite catalysis have become increasingly cognizant of the diversity in structure and function resulting from the distribution of framework aluminum atoms, through emerging reports of catalytic phenomena that fall outside those recognizable as the shape-selective ones emblematic of its earlier history. Molecular-level descriptions of how active-site distributions affect catalysis are an aspirational goal articulated frequently in experimental and theoretical research, yet they are limited by imprecise knowledge of the structure and behavior of the zeolite materials under interrogation. In experimental research, higher precision can result from more reliable control of structure during synthesis and from more robustmore » and quantitative structural and kinetic characterization probes. In theoretical research, construction of models with specific aluminum locations and distributions seldom capture the heterogeneity inherent to the materials studied by experiment. In this Perspective, we discuss research findings that appropriately frame the challenges in developing more predictive synthesis-structure-function relations for zeolites, highlighting studies on ZSM-5 zeolites that are among the most structurally complex molecular sieve frameworks and the most widely studied because of their versatility in commercial applications. We discuss research directions to address these challenges and forge stronger connections between zeolite structure, composition, and active sites to catalytic function. Such connections promise to aid in bridging the findings of theoretical and experimental catalysis research, and transforming zeolite active site design from an empirical endeavor into a more predictable science founded on validated models.« less

Consideration of the Aluminum Distribution in Zeolites in Theoretical and Experimental Catalysis Research

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

Knott, Brandon C.; Nimlos, Claire T.; Robichaud, David J.

Research efforts in zeolite catalysis have become increasingly cognizant of the diversity in structure and function resulting from the distribution of framework aluminum atoms, through emerging reports of catalytic phenomena that fall outside those recognizable as the shape-selective ones emblematic of its earlier history. Molecular-level descriptions of how active-site distributions affect catalysis are an aspirational goal articulated frequently in experimental and theoretical research, yet they are limited by imprecise knowledge of the structure and behavior of the zeolite materials under interrogation. In experimental research, higher precision can result from more reliable control of structure during synthesis and from more robustmore » and quantitative structural and kinetic characterization probes. In theoretical research, construction of models with specific aluminum locations and distributions seldom capture the heterogeneity inherent to the materials studied by experiment. In this Perspective, we discuss research findings that appropriately frame the challenges in developing more predictive synthesis-structure-function relations for zeolites, highlighting studies on ZSM-5 zeolites that are among the most structurally complex molecular sieve frameworks and the most widely studied because of their versatility in commercial applications. We discuss research directions to address these challenges and forge stronger connections between zeolite structure, composition, and active sites to catalytic function. Such connections promise to aid in bridging the findings of theoretical and experimental catalysis research, and transforming zeolite active site design from an empirical endeavor into a more predictable science founded on validated models.« less

In situ DART-MS as a Versatile and Rapid Dereplication Tool in Lichenology: Chemical Fingerprinting of Ophioparma ventosa.

PubMed

Le Pogam, Pierre; Le Lamer, Anne-Cécile; Legouin, Béatrice; Boustie, Joël; Rondeau, David

2016-11-01

Lichens widely occur all over the world and are known to produce unique secondary metabolites with various biological activities. To develop high-throughput screening approaches requiring little to no sample preparation to alleviate the dereplication holdup and accelerate the discovery workflow of new structures from lichens. The extracellular distribution of lichen metabolites is incentive for in situ chemical profiling of lichens using the ambient mass spectrometry DART-MS. For this purpose, the chlorolichen Ophioparma ventosa, producing an array of lichen polyphenolics that encompass the main structural classes associated to lichen chemodiversity, represented a relevant model to assess the versatility of this platform. The feasibility of this approach was first established by analysing the pure compounds known from this species prior to being extended to different solid organs of the lichen. All tested compounds could be detected in positive and negative ion modes, most often with prevalent protonated or deprotonated molecules. Only depsides underwent a significant in-source fragmentation in both ionisation modes, which should be regarded as an added value for their structural elucidation. In situ DART-MS analyses of Ophioparma ventosa provided an extensive chemical profile and noteworthy pinpointed miriquidic acid, an unusual lichen depside so far unknown within this species. At last, in situ DART-MS granted a first insight into the distribution of the metabolites within the lichen. DART-MS represents a versatile tool to the wide field of lichenology, facilitating accelerated and sharp analyses of lichens and bypassing costly and tedious procedures of solvent extraction. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Steroid Sulfatase Inhibition by Aryl Sulfamates: Clinical Progress, Mechanism and Future Prospects.

PubMed

Potter, Barry V L

2018-04-04

Steroid sulfatase is an emerging drug target for the endocrine therapy of hormone-dependent diseases, catalyzing estrogen sulfate hydrolysis to estrogen. Drug discovery, developing the core aryl O-sulfamate pharmacophore, has led to steroidal and non-steroidal drugs entering numerous clinical trials, with promising results in oncology and women's health. Steroidal estrogen sulfamate derivatives were the first irreversible active-site-directed inhibitors and one was developed clinically as an oral estradiol pro-drug and for endometriosis applications. This review summarizes work leading to the therapeutic concept of sulfatase inhibition, clinical trials executed to date and new insights into the mechanism of inhibition of steroid sulfatase. To date the non-steroidal sulfatase inhibitor Irosustat has been evaluated clinically in breast cancer, alone and in combination, in endometrial cancer and in prostate cancer. The versatile core pharmacophore both imbues attractive pharmaceutical properties and functions via three distinct mechanisms of action, as a pro-drug, an enzyme active site-modifying motif, likely through direct sulfamoyl group transfer, and as a structural component augmenting activity, for example by enhancing interactions at the colchicine binding site of tubulin. Preliminary new structural data on the Pseudomonas aeruginosa arylsulfatase enzyme suggest two possible sulfamate-based adducts with active site hydrated formylglycine as candidates for the inhibition end product via sulfamoyl group transfer, and a speculative choice is suggested. The clinical status of sulfatase inhibition is surveyed and how it might develop in the future. Also discussed are dual-targeting approaches, development of 2-substituted steroidal sulfamates and nonsteroidal derivatives as multi-targeting agents for hormone-independent tumours with other emerging directions.

A versatile system for the rapid collection, handling and graphics analysis of multidimensional data

NASA Astrophysics Data System (ADS)

O'Brien, P. M.; Moloney, G.; O'Connor, A.; Legge, G. J. F.

1993-05-01

The aim of this work was to provide a versatile system for handling multiparameter data that may arise from a variety of experiments — nuclear, AMS, microprobe elemental analysis, 3D microtomography etc. Some of the most demanding requirements arise in the application of microprobes to quantitative elemental mapping and to microtomography. A system to handle data from such experiments had been under continuous development and use at MARC for the past 15 years. It has now been made adaptable to the needs of multiparameter (or single parameter) experiments in general. The original system has been rewritten, greatly expanded and made much more powerful and faster, by use of modern computer technology — a VME bus computer with a real time operating system and a RISC workstation running Unix and the X Window system. This provides the necessary (i) power, speed and versatility, (ii) expansion and updating capabilities (iii) standardisation and adaptability, (iv) coherent modular programming structures, (v) ability to interface to other programs and (vi) transparent operation with several levels, involving the use of menus, programmed function keys and powerful macro programming facilities.

Pushing the frontiers of first-principles based computer simulations of chemical and biological systems.

PubMed

Brunk, Elizabeth; Ashari, Negar; Athri, Prashanth; Campomanes, Pablo; de Carvalho, F Franco; Curchod, Basile F E; Diamantis, Polydefkis; Doemer, Manuel; Garrec, Julian; Laktionov, Andrey; Micciarelli, Marco; Neri, Marilisa; Palermo, Giulia; Penfold, Thomas J; Vanni, Stefano; Tavernelli, Ivano; Rothlisberger, Ursula

2011-01-01

The Laboratory of Computational Chemistry and Biochemistry is active in the development and application of first-principles based simulations of complex chemical and biochemical phenomena. Here, we review some of our recent efforts in extending these methods to larger systems, longer time scales and increased accuracies. Their versatility is illustrated with a diverse range of applications, ranging from the determination of the gas phase structure of the cyclic decapeptide gramicidin S, to the study of G protein coupled receptors, the interaction of transition metal based anti-cancer agents with protein targets, the mechanism of action of DNA repair enzymes, the role of metal ions in neurodegenerative diseases and the computational design of dye-sensitized solar cells. Many of these projects are done in collaboration with experimental groups from the Institute of Chemical Sciences and Engineering (ISIC) at the EPFL.

CVD-Enabled Graphene Manufacture and Technology

PubMed Central

2015-01-01

Integrated manufacturing is arguably the most challenging task in the development of technology based on graphene and other 2D materials, particularly with regard to the industrial demand for “electronic-grade” large-area films. In order to control the structure and properties of these materials at the monolayer level, their nucleation, growth and interfacing needs to be understood to a level of unprecedented detail compared to existing thin film or bulk materials. Chemical vapor deposition (CVD) has emerged as the most versatile and promising technique to develop graphene and 2D material films into industrial device materials and this Perspective outlines recent progress, trends, and emerging CVD processing pathways. A key focus is the emerging understanding of the underlying growth mechanisms, in particular on the role of the required catalytic growth substrate, which brings together the latest progress in the fields of heterogeneous catalysis and classic crystal/thin-film growth. PMID:26240694

Plant Lectins and Lectin Receptor-Like Kinases: How Do They Sense the Outside?

PubMed Central

Bellande, Kevin; Bono, Jean-Jacques; Savelli, Bruno; Jamet, Elisabeth; Canut, Hervé

2017-01-01

Lectins are fundamental to plant life and have important roles in cell-to-cell communication; development and defence strategies. At the cell surface; lectins are present both as soluble proteins (LecPs) and as chimeric proteins: lectins are then the extracellular domains of receptor-like kinases (LecRLKs) and receptor-like proteins (LecRLPs). In this review; we first describe the domain architectures of proteins harbouring G-type; L-type; LysM and malectin carbohydrate-binding domains. We then focus on the functions of LecPs; LecRLKs and LecRLPs referring to the biological processes they are involved in and to the ligands they recognize. Together; LecPs; LecRLKs and LecRLPs constitute versatile recognition systems at the cell surface contributing to the detection of symbionts and pathogens; and/or involved in monitoring of the cell wall structure and cell growth. PMID:28561754

Plant Lectins and Lectin Receptor-Like Kinases: How Do They Sense the Outside?

PubMed

Bellande, Kevin; Bono, Jean-Jacques; Savelli, Bruno; Jamet, Elisabeth; Canut, Hervé

2017-05-31

Lectins are fundamental to plant life and have important roles in cell-to-cell communication; development and defence strategies. At the cell surface; lectins are present both as soluble proteins (LecPs) and as chimeric proteins: lectins are then the extracellular domains of receptor-like kinases (LecRLKs) and receptor-like proteins (LecRLPs). In this review; we first describe the domain architectures of proteins harbouring G-type; L-type; LysM and malectin carbohydrate-binding domains. We then focus on the functions of LecPs; LecRLKs and LecRLPs referring to the biological processes they are involved in and to the ligands they recognize. Together; LecPs; LecRLKs and LecRLPs constitute versatile recognition systems at the cell surface contributing to the detection of symbionts and pathogens; and/or involved in monitoring of the cell wall structure and cell growth.

Versatile Aggressive Mimicry of Cicadas by an Australian Predatory Katydid

PubMed Central

Marshall, David C.; Hill, Kathy B. R.

2009-01-01

Background In aggressive mimicry, a predator or parasite imitates a signal of another species in order to exploit the recipient of the signal. Some of the most remarkable examples of aggressive mimicry involve exploitation of a complex signal-response system by an unrelated predator species. Methodology/Principal Findings We have found that predatory Chlorobalius leucoviridis katydids (Orthoptera: Tettigoniidae) can attract male cicadas (Hemiptera: Cicadidae) by imitating the species-specific wing-flick replies of sexually receptive female cicadas. This aggressive mimicry is accomplished both acoustically, with tegminal clicks, and visually, with synchronized body jerks. Remarkably, the katydids respond effectively to a variety of complex, species-specific Cicadettini songs, including songs of many cicada species that the predator has never encountered. Conclusions/Significance We propose that the versatility of aggressive mimicry in C. leucoviridis is accomplished by exploiting general design elements common to the songs of many acoustically signaling insects that use duets in pair-formation. Consideration of the mechanism of versatile mimicry in C. leucoviridis may illuminate processes driving the evolution of insect acoustic signals, which play a central role in reproductive isolation of populations and the formation of species. PMID:19142230

Identification, characterization, and expression analysis of calmodulin and calmodulin-like genes in grapevine (Vitis vinifera) reveal likely roles in stress responses.

PubMed

Vandelle, Elodie; Vannozzi, Alessandro; Wong, Darren; Danzi, Davide; Digby, Anne-Marie; Dal Santo, Silvia; Astegno, Alessandra

2018-06-04

Calcium (Ca 2+ ) is an ubiquitous key second messenger in plants, where it modulates many developmental and adaptive processes in response to various stimuli. Several proteins containing Ca 2+ binding domain have been identified in plants, including calmodulin (CaM) and calmodulin-like (CML) proteins, which play critical roles in translating Ca 2+ signals into proper cellular responses. In this work, a genome-wide analysis conducted in Vitis vinifera identified three CaM- and 62 CML-encoding genes. We assigned gene family nomenclature, analyzed gene structure, chromosomal location and gene duplication, as well as protein motif organization. The phylogenetic clustering revealed a total of eight subgroups, including one unique clade of VviCaMs distinct from VviCMLs. VviCaMs were found to contain four EF-hand motifs whereas VviCML proteins have one to five. Most of grapevine CML genes were intronless, while VviCaMs were intron rich. All the genes were well spread among the 19 grapevine chromosomes and displayed a high level of duplication. The expression profiling of VviCaM/VviCML genes revealed a broad expression pattern across all grape organs and tissues at various developmental stages, and a significant modulation in biotic stress-related responses. Our results highlight the complexity of CaM/CML protein family also in grapevine, supporting the versatile role of its different members in modulating cellular responses to various stimuli, in particular to biotic stresses. This work lays the foundation for further functional and structural studies on specific grapevine CaMs/CMLs in order to better understand the role of Ca 2+ -binding proteins in grapevine and to explore their potential for further biotechnological applications. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

Imaging of current distributions in superconducting thin film structures

NASA Astrophysics Data System (ADS)

Dönitz, Dietmar

2006-10-01

Local analysis plays an important role in many fields of scientific research. However, imaging methods are not very common in the investigation of superconductors. For more than 20 years, Low Temperature Scanning Electron Microscopy (LTSEM) has been successfully used at the University of Tübingen for studying of condensed matter phenomena, especially of superconductivity. In this thesis LTSEM was used for imaging current distributions in different superconducting thin film structures: - Imaging of current distributions in Josephson junctions with ferromagnetic interlayer, also known as SIFS junctions, showed inhomogeneous current transport over the junctions which directly led to an improvement in the fabrication process. An investigation of improved samples showed a very homogeneous current distribution without any trace of magnetic domains. Either such domains were not present or too small for imaging with the LTSEM. - An investigation of Nb/YBCO zigzag Josephson junctions yielded important information on signal formation in the LTSEM both for Josephson junctions in the short and in the long limit. Using a reference junction our signal formation model could be verified, thus confirming earlier results on short zigzag junctions. These results, which could be reproduced in this work, support the theory of d-wave symmetry in the superconducting order parameter of YBCO. Furthermore, investigations of the quasiparticle tunneling in the zigzag junctions showed the existence of Andreev bound states, which is another indication of the d-wave symmetry in YBCO. - The LTSEM study of Hot Electron Bolometers (HEB) allowed the first successful imaging of a stable 'Hot Spot', a self-heating region in HEB structures. Moreover, the electron beam was used to induce an - otherwise unstable - hot spot. Both investigations yielded information on the homogeneity of the samples. - An entirely new method of imaging the current distribution in superconducting interference devices (SQUIDs) could be developed. It is based on vortex imaging by LTSEM that had been established several years ago. The vortex signals can be used as local detectors for the vortex-free circulating sheet-current distribution J. Compared to previous inversion methods that infer J from the measured magnetic field, this method gives a more direct measurement of the current distribution. The experimental results were in very good agreement with numerical calculations of J. The presented investigations show how versatile and useful Low Temperature Scanning Electron Microscopy can be for studying superconducting thin film structures. Thus one may expect that many more important results can be obtained with this method.

The U.S. Diplomatic Role in Lebanon’s Struggle for Independence during the Second World War

DTIC Science & Technology

1990-05-01

web of issues and events of the Second World War. In order to understand the attempts of Lebanese nationalists to influence the U.S. diplomatic role in...FRANCE, FEAR OF GERMANS, FINIS TO MANDATE? L’administration du Mandat etait changeante et versatile. Elle se caracterisait en outre par une indifference...quasi volontaire aux besoins veritables du Liban, surtout dans le domaine economique. De 1924 a 1939, le Liban eut au moins quatre formes differentes

Vitamin C: electron emission, free radicals and biological versatility.

PubMed

Getoff, Nikola

2013-01-01

The many-sided biological role of vitamin C (ascorbate) is briefly illustrated by specific examples. It is demonstrated that in aqueous solutions, vitamin C emits solvated electrons (e(aq)(-)), when excited in single state. Vitamin C can also react with e(aq)(-) as well as transfer them to other biological systems and thereby acts as efficient electron mediator. Based on its chemical and biological properties, it is clear that vitamin C plays a very important role in various functions in the organism alongside biochemical processes.

SAFSIM theory manual: A computer program for the engineering simulation of flow systems

NASA Astrophysics Data System (ADS)

Dobranich, Dean

1993-12-01

SAFSIM (System Analysis Flow SIMulator) is a FORTRAN computer program for simulating the integrated performance of complex flow systems. SAFSIM provides sufficient versatility to allow the engineering simulation of almost any system, from a backyard sprinkler system to a clustered nuclear reactor propulsion system. In addition to versatility, speed and robustness are primary SAFSIM development goals. SAFSIM contains three basic physics modules: (1) a fluid mechanics module with flow network capability; (2) a structure heat transfer module with multiple convection and radiation exchange surface capability; and (3) a point reactor dynamics module with reactivity feedback and decay heat capability. Any or all of the physics modules can be implemented, as the problem dictates. SAFSIM can be used for compressible and incompressible, single-phase, multicomponent flow systems. Both the fluid mechanics and structure heat transfer modules employ a one-dimensional finite element modeling approach. This document contains a description of the theory incorporated in SAFSIM, including the governing equations, the numerical methods, and the overall system solution strategies.

Versatility of Evaporation-Induced Self-Assembly (EISA) Method for Preparation of Mesoporous TiO2 for Energy and Environmental Applications

PubMed Central

Mahoney, Luther; Koodali, Ranjit T.

2014-01-01

Evaporation-Induced Self-Assembly (EISA) method for the preparation of mesoporous titanium dioxide materials is reviewed. The versatility of EISA method for the rapid and facile synthesis of TiO2 thin films and powders is highlighted. Non-ionic surfactants such as Pluronic P123, F127 and cationic surfactants such as cetyltrimethylammonium bromide have been extensively employed for the preparation of mesoporous TiO2. In particular, EISA method allows for fabrication of highly uniform, robust, crack-free films with controllable thickness. Eleven characterization techniques for elucidating the structure of the EISA prepared mesoporous TiO2 are discussed in this paper. These many characterization methods provide a holistic picture of the structure of mesoporous TiO2. Mesoporous titanium dioxide materials have been employed in several applications that include Dye Sensitized Solar Cells (DSSCs), photocatalytic degradation of organics and splitting of water, and batteries. PMID:28788590

3D Printing Polymers with Supramolecular Functionality for Biological Applications.

PubMed

Pekkanen, Allison M; Mondschein, Ryan J; Williams, Christopher B; Long, Timothy E

2017-09-11

Supramolecular chemistry continues to experience widespread growth, as fine-tuned chemical structures lead to well-defined bulk materials. Previous literature described the roles of hydrogen bonding, ionic aggregation, guest/host interactions, and π-π stacking to tune mechanical, viscoelastic, and processing performance. The versatility of reversible interactions enables the more facile manufacturing of molded parts with tailored hierarchical structures such as tissue engineered scaffolds for biological applications. Recently, supramolecular polymers and additive manufacturing processes merged to provide parts with control of the molecular, macromolecular, and feature length scales. Additive manufacturing, or 3D printing, generates customizable constructs desirable for many applications, and the introduction of supramolecular interactions will potentially increase production speed, offer a tunable surface structure for controlling cell/scaffold interactions, and impart desired mechanical properties through reinforcing interlayer adhesion and introducing gradients or self-assembled structures. This review details the synthesis and characterization of supramolecular polymers suitable for additive manufacture and biomedical applications as well as the use of supramolecular polymers in additive manufacturing for drug delivery and complex tissue scaffold formation. The effect of supramolecular assembly and its dynamic behavior offers potential for controlling the anisotropy of the printed objects with exquisite geometrical control. The potential for supramolecular polymers to generate well-defined parts, hierarchical structures, and scaffolds with gradient properties/tuned surfaces provides an avenue for developing next-generation biomedical devices and tissue scaffolds.

Now You Hear It, Now You Don't: Vowel Devoicing in Japanese Infant-Directed Speech

ERIC Educational Resources Information Center

Fais, Laurel; Kajikawa, Sachiyo; Amano, Shigeaki; Werker, Janet F.

2010-01-01

In this work, we examine a context in which a conflict arises between two roles that infant-directed speech (IDS) plays: making language structure salient and modeling the adult form of a language. Vowel devoicing in fluent adult Japanese creates violations of the canonical Japanese consonant-vowel word structure pattern by systematically…